svn merge --reintegrate https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535 back to trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1574259 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/LightWeightGSet.java

@@ -244,13 +244,14 @@ public class LightWeightGSet<K, E extends K> implements GSet<K, E> {
     out.println("\n]");
   }
 
-  private class SetIterator implements Iterator<E> {
+  public class SetIterator implements Iterator<E> {
     /** The starting modification for fail-fast. */
     private int iterModification = modification;
     /** The current index of the entry array. */
     private int index = -1;
     private LinkedElement cur = null;
     private LinkedElement next = nextNonemptyEntry();
+    private boolean trackModification = true;
 
     /** Find the next nonempty entry starting at (index + 1). */
     private LinkedElement nextNonemptyEntry() {
@@ -259,7 +260,7 @@ public class LightWeightGSet<K, E extends K> implements GSet<K, E> {
     }
 
     private void ensureNext() {
-      if (modification != iterModification) {
+      if (trackModification && modification != iterModification) {
         throw new ConcurrentModificationException("modification=" + modification
             + " != iterModification = " + iterModification);
       }
@@ -304,6 +305,10 @@ public class LightWeightGSet<K, E extends K> implements GSet<K, E> {
       iterModification++;
       cur = null;
     }
+
+    public void setTrackModification(boolean trackModification) {
+      this.trackModification = trackModification;
+    }
   }
   
   /**

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -250,6 +250,148 @@ Trunk (Unreleased)
     HDFS-5794. Fix the inconsistency of layout version number of 
     ADD_DATANODE_AND_STORAGE_UUIDS between trunk and branch-2. (jing9)
 
+BREAKDOWN OF HDFS-5535 ROLLING UPGRADE SUBTASKS AND RELATED JIRAS
+
+    HDFS-5496. Make replication queue initialization asynchronous. (Vinay via
+    jing9)
+
+    HDFS-5645. Support upgrade marker in editlog streams. (szetszwo)
+
+    HDFS-5752. Add a new DFSAdmin command to query, start and finalize rolling
+    upgrade. (szetszwo)
+
+    HDFS-5786. Support QUERY and FINALIZE actions of rolling upgrade. (szetszwo)
+
+    HDFS-5753. Add new Namenode startup options for downgrade and rollback using
+    upgrade marker. (szetszwo)
+
+    HDFS-5835. Add a new option for starting Namenode when rolling upgrade is
+    in progress. (szetszwo)
+
+    HDFS-5754. Split LayoutVerion into NameNodeLayoutVersion and
+    DataNodeLayoutVersion. (Brandon Li via szetszwo)
+
+    HDFS-5848. Add rolling upgrade status to heartbeat response. (szetszwo)
+
+    HDFS-5890. Avoid NPE in Datanode heartbeat. (Vinay via brandonli)
+
+    HDFS-5869. When starting rolling upgrade or NN restarts, NN should create
+    a checkpoint right before the upgrade marker.  (szetszwo)
+
+    HDFS-5874. Should not compare DataNode current layout version with that of
+    NameNode in DataStrorage. (brandonli)
+
+    HDFS-5889. When starting rolling upgrade, create a fs image for rollback
+    so that the standby namenode can create checkpoints during upgrade.
+    (szetszwo & jing9)
+
+    HDFS-5907. Add BlockPoolSliceStorage 'trash' to handle block deletions
+    during rolling upgrades. (Arpit Agarwal)
+
+    HDFS-5494. Merge Protobuf-based-FSImage code from trunk - fix build
+    break after the merge. (Jing Zhao via Arpit Agarwal)
+
+    HDFS-5585. Provide admin commands for data node upgrade (kihwal)
+
+    HDFS-5920. Support rollback of rolling upgrade in NameNode and JournalNodes.
+    (jing9)
+
+    HDFS-5945. Add rolling upgrade information to fsimage; and disallow upgrade
+    and rolling upgrade to be started simultaneously.  (szetszwo & jing9)
+
+    HDFS-5966. Fix rollback of rolling upgrade in NameNode HA setup.  (jing9
+    via szetszwo)
+
+    HDFS-5974. Fix compilation error, NameNodeLayoutVersion and
+    DataNodeLayoutVersion after merge from trunk.  (szetszwo)
+
+    HDFS-5963. TestRollingUpgrade#testSecondaryNameNode causes subsequent
+    tests to fail. (szetszwo via Arpit Agarwal)
+
+    HDFS-5976. Create unit tests for downgrade and finalize rolling upgrade.
+    (Haohui Mai via Arpit Agarwal)
+
+    HDFS-5980. Rollback does not need to load edits.  (jing9 via szetszwo)
+
+    HDFS-5984. Fix TestEditLog and TestStandbyCheckpoints.  (jing9 via szetszwo)
+
+    HDFS-5985. SimulatedFSDataset#disableAndPurgeTrashStorage should not throw
+    UnsupportedOperationException. (jing9 via kihwal)
+
+    HDFS-5987. Fix findbugs warnings in Rolling Upgrade branch. (seztszwo via
+    Arpit Agarwal)
+
+    HDFS-5992. Fix NPE in MD5FileUtils and update editsStored for
+    TestOfflineEditsViewer.  (szetszwo)
+
+    HDFS-5994. Fix TestDataNodeRollingUpgrade.  (Arpit Agarwal via szetszwo)
+
+    HDFS-5999. Do not create rollback fsimage when it already exists. (jing9)
+
+    HDFS-6005. Simplify Datanode rollback and downgrade. (Suresh Srinivas via
+    Arpit Agarwal)
+
+    HDFS-6004. Change DFSAdmin for rolling upgrade commands. (szetszwo via
+    Arpit Agarwal)
+
+    HDFS-5583. Make DN send an OOB Ack on shutdown before restarting. (kihwal)
+
+    HDFS-5778. Add rolling upgrade user document. (szetszwo)
+
+    HDFS-6003. Add the new -rollingUpgrade startup option to the namenode
+    usage message. (Vinayakumar B via szetszwo)
+
+    HDFS-6014. Fix findbug warnings introduced by HDFS-5583. (kihwal)
+
+    HDFS-6015. Fix TestBlockRecovery
+    #testRaceBetweenReplicaRecoveryAndFinalizeBlock. (kihwal)
+
+    HDFS-5924. Utilize OOB upgrade message processing for writes. (kihwal)
+
+    HDFS-5498. Improve datanode startup time. (kihwal)
+
+    HDFS-6000. Avoid saving namespace when starting rolling upgrade. (jing9)
+
+    HDFS-6017. Query the status of rolling upgrade in the preparation stage in
+    TestRollingUpgrade and TestRollingUpgradeRollback. (Haohui Mai via
+    Arpit Agarwal)
+
+    HDFS-6020. Fix the five findbugs warnings. (kihwal)
+
+    HDFS-6019. Standby NN might not checkpoint when processing the rolling
+    upgrade marker. (Haohui Mai via jing9)
+
+    HDFS-6023. Test whether the standby NN continues to checkpoint after the
+    prepare stage. (Haohui Mai via jing9)
+
+    HDFS-6024. Test whether the NN will reject the downgrade if it has a
+    fsimage from a newer release. (Haohui Mai via jing9)
+
+    HDFS-6026. Fix TestDFSUpgrade and TestDataNodeRollingUpgrade.
+    (jing9 via szetszwo)
+
+    HDFS-6029. Secondary NN fails to checkpoint after -rollingUpgrade prepare.
+    (jing9)
+
+    HDFS-6032. -rollingUpgrade query hits NPE after the NN restarts. (Haohui Mai
+    via jing9)
+
+    HDFS-6031. Add back the "-rollingUpgrade started" namenode startup option;
+    otherwise, namenode cannot start when the layout version is changed.
+    (szetszwo)
+
+    HDFS-6034. Use DataNodeLayoutVersion for DN registration check and do not
+    verify layout version if there is a rolling upgrade in progress.  (szetszwo)
+
+    HDFS-6013. add rollingUpgrade information to latest UI.
+    (Vinayakumar B via wheat9)
+
+    HDFS-6042. Fix rolling upgrade documentation and error messages. (szetszwo
+    via Arpit Agarwal)
+
+    HDFS-6041. Downgrade/Finalize should rename the rollback image instead of
+    purging it. (jing9)
+
 Release 2.5.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/contrib/bkjournal/src/main/java/org/apache/hadoop/contrib/bkjournal/BookKeeperJournalManager.java

@@ -397,7 +397,7 @@ public class BookKeeperJournalManager implements JournalManager {
     try {
       String znodePath = inprogressZNode(txId);
       EditLogLedgerMetadata l = new EditLogLedgerMetadata(znodePath,
-          HdfsConstants.LAYOUT_VERSION, currentLedger.getId(), txId);
+          HdfsConstants.NAMENODE_LAYOUT_VERSION, currentLedger.getId(), txId);
       /* Write the ledger metadata out to the inprogress ledger znode
        * This can fail if for some reason our write lock has
        * expired (@see WriteLock) and another process has managed to
@@ -692,6 +692,11 @@ public class BookKeeperJournalManager implements JournalManager {
     throw new UnsupportedOperationException();
   }
 
+  @Override
+  public void discardSegments(long startTxId) throws IOException {
+    throw new UnsupportedOperationException();
+  }
+
   @Override
   public void close() throws IOException {
     try {

hadoop-hdfs-project/hadoop-hdfs/src/contrib/bkjournal/src/test/java/org/apache/hadoop/contrib/bkjournal/TestBookKeeperEditLogStreams.java

@@ -68,7 +68,7 @@ public class TestBookKeeperEditLogStreams {
       lh.close();
 
       EditLogLedgerMetadata metadata = new EditLogLedgerMetadata("/foobar",
-          HdfsConstants.LAYOUT_VERSION, lh.getId(), 0x1234);
+          HdfsConstants.NAMENODE_LAYOUT_VERSION, lh.getId(), 0x1234);
       try {
         new BookKeeperEditLogInputStream(lh, metadata, -1);
         fail("Shouldn't get this far, should have thrown");
@@ -77,7 +77,7 @@ public class TestBookKeeperEditLogStreams {
       }
 
       metadata = new EditLogLedgerMetadata("/foobar",
-          HdfsConstants.LAYOUT_VERSION, lh.getId(), 0x1234);
+          HdfsConstants.NAMENODE_LAYOUT_VERSION, lh.getId(), 0x1234);
       try {
         new BookKeeperEditLogInputStream(lh, metadata, 0);
         fail("Shouldn't get this far, should have thrown");

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSClient.java

@@ -30,6 +30,8 @@ import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_CLIENT_CACHED_CONN_RETRY_
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_CLIENT_CACHE_DROP_BEHIND_READS;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_CLIENT_CACHE_DROP_BEHIND_WRITES;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_CLIENT_CACHE_READAHEAD;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_CLIENT_DATANODE_RESTART_TIMEOUT_KEY;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_CLIENT_DATANODE_RESTART_TIMEOUT_DEFAULT;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_CLIENT_FAILOVER_MAX_ATTEMPTS_DEFAULT;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_CLIENT_FAILOVER_MAX_ATTEMPTS_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_CLIENT_FAILOVER_SLEEPTIME_BASE_DEFAULT;
@@ -136,11 +138,13 @@ import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsBlocksMetadata;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.RollingUpgradeAction;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
 import org.apache.hadoop.hdfs.protocol.NSQuotaExceededException;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeInfo;
 import org.apache.hadoop.hdfs.protocol.SnapshotAccessControlException;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
@@ -267,6 +271,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory {
     final int getFileBlockStorageLocationsTimeoutMs;
     final int retryTimesForGetLastBlockLength;
     final int retryIntervalForGetLastBlockLength;
+    final long datanodeRestartTimeout;
 
     final boolean useLegacyBlockReader;
     final boolean useLegacyBlockReaderLocal;
@@ -417,6 +422,10 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory {
       shortCircuitSharedMemoryWatcherInterruptCheckMs = conf.getInt(
           DFSConfigKeys.DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS,
           DFSConfigKeys.DFS_SHORT_CIRCUIT_SHARED_MEMORY_WATCHER_INTERRUPT_CHECK_MS_DEFAULT);
+
+      datanodeRestartTimeout = conf.getLong(
+          DFS_CLIENT_DATANODE_RESTART_TIMEOUT_KEY,
+          DFS_CLIENT_DATANODE_RESTART_TIMEOUT_DEFAULT) * 1000;
     }
 
     private DataChecksum.Type getChecksumType(Configuration conf) {
@@ -2458,6 +2467,10 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory {
     namenode.finalizeUpgrade();
   }
 
+  RollingUpgradeInfo rollingUpgrade(RollingUpgradeAction action) throws IOException {
+    return namenode.rollingUpgrade(action);
+  }
+
   /**
    */
   @Deprecated

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java

@@ -94,6 +94,10 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
   public static final long    DFS_CLIENT_SOCKET_CACHE_EXPIRY_MSEC_DEFAULT = 3000;
   public static final String  DFS_CLIENT_WRITE_EXCLUDE_NODES_CACHE_EXPIRY_INTERVAL = "dfs.client.write.exclude.nodes.cache.expiry.interval.millis";
   public static final long    DFS_CLIENT_WRITE_EXCLUDE_NODES_CACHE_EXPIRY_INTERVAL_DEFAULT = 10 * 60 * 1000; // 10 minutes, in ms
+  public static final String  DFS_CLIENT_DATANODE_RESTART_TIMEOUT_KEY = "dfs.client.datanode-restart.timeout";
+  public static final long    DFS_CLIENT_DATANODE_RESTART_TIMEOUT_DEFAULT = 30;
+  public static final String  DFS_DATANODE_RESTART_REPLICA_EXPIRY_KEY = "dfs.datanode.restart.replica.expiration";
+  public static final long    DFS_DATANODE_RESTART_REPLICA_EXPIRY_DEFAULT = 50;
   public static final String  DFS_NAMENODE_BACKUP_ADDRESS_KEY = "dfs.namenode.backup.address";
   public static final String  DFS_NAMENODE_BACKUP_ADDRESS_DEFAULT = "localhost:50100";
   public static final String  DFS_NAMENODE_BACKUP_HTTP_ADDRESS_KEY = "dfs.namenode.backup.http-address";
@@ -225,6 +229,8 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
   public static final boolean DFS_DATANODE_SYNCONCLOSE_DEFAULT = false;
   public static final String  DFS_DATANODE_SOCKET_REUSE_KEEPALIVE_KEY = "dfs.datanode.socket.reuse.keepalive";
   public static final int     DFS_DATANODE_SOCKET_REUSE_KEEPALIVE_DEFAULT = 4000;
+  public static final String  DFS_DATANODE_OOB_TIMEOUT_KEY = "dfs.datanode.oob.timeout-ms";
+  public static final String  DFS_DATANODE_OOB_TIMEOUT_DEFAULT = "1500,0,0,0"; // OOB_TYPE1, OOB_TYPE2, OOB_TYPE3, OOB_TYPE4
 
   public static final String DFS_NAMENODE_DATANODE_REGISTRATION_IP_HOSTNAME_CHECK_KEY = "dfs.namenode.datanode.registration.ip-hostname-check";
   public static final boolean DFS_NAMENODE_DATANODE_REGISTRATION_IP_HOSTNAME_CHECK_DEFAULT = true;
@@ -416,7 +422,9 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
   public static final int     DFS_BLOCK_INVALIDATE_LIMIT_DEFAULT = 1000;
   public static final String  DFS_DEFAULT_MAX_CORRUPT_FILES_RETURNED_KEY = "dfs.corruptfilesreturned.max";
   public static final int     DFS_DEFAULT_MAX_CORRUPT_FILES_RETURNED = 500;
-
+  /* Maximum number of blocks to process for initializing replication queues */
+  public static final String  DFS_BLOCK_MISREPLICATION_PROCESSING_LIMIT = "dfs.block.misreplication.processing.limit";
+  public static final int     DFS_BLOCK_MISREPLICATION_PROCESSING_LIMIT_DEFAULT = 10000;
   public static final String DFS_CLIENT_READ_SHORTCIRCUIT_KEY = "dfs.client.read.shortcircuit";
   public static final boolean DFS_CLIENT_READ_SHORTCIRCUIT_DEFAULT = false;
   public static final String DFS_CLIENT_READ_SHORTCIRCUIT_SKIP_CHECKSUM_KEY = "dfs.client.read.shortcircuit.skip.checksum";

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java

@@ -27,6 +27,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.InterruptedIOException;
 import java.io.OutputStream;
+import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.Socket;
 import java.nio.BufferOverflowException;
@@ -335,6 +336,8 @@ public class DFSOutputStream extends FSOutputSummer
     private String[] favoredNodes;
     volatile boolean hasError = false;
     volatile int errorIndex = -1;
+    volatile int restartingNodeIndex = -1; // Restarting node index
+    private long restartDeadline = 0; // Deadline of DN restart
     private BlockConstructionStage stage;  // block construction stage
     private long bytesSent = 0; // number of bytes that've been sent
 
@@ -471,7 +474,7 @@ public class DFSOutputStream extends FSOutputSummer
         try {
           // process datanode IO errors if any
           boolean doSleep = false;
-          if (hasError && errorIndex>=0) {
+          if (hasError && (errorIndex >= 0 || restartingNodeIndex >= 0)) {
             doSleep = processDatanodeError();
           }
 
@@ -571,8 +574,12 @@ public class DFSOutputStream extends FSOutputSummer
             blockStream.flush();   
           } catch (IOException e) {
             // HDFS-3398 treat primary DN is down since client is unable to 
-            // write to primary DN
-            errorIndex = 0;
+            // write to primary DN. If a failed or restarting node has already
+            // been recorded by the responder, the following call will have no 
+            // effect. Pipeline recovery can handle only one node error at a
+            // time. If the primary node fails again during the recovery, it
+            // will be taken out then.
+            tryMarkPrimaryDatanodeFailed();
             throw e;
           }
           lastPacket = Time.now();
@@ -609,12 +616,16 @@ public class DFSOutputStream extends FSOutputSummer
             Thread.sleep(artificialSlowdown); 
           }
         } catch (Throwable e) {
-          DFSClient.LOG.warn("DataStreamer Exception", e);
+          // Log warning if there was a real error.
+          if (restartingNodeIndex == -1) {
+            DFSClient.LOG.warn("DataStreamer Exception", e);
+          }
           if (e instanceof IOException) {
             setLastException((IOException)e);
           }
           hasError = true;
-          if (errorIndex == -1) { // not a datanode error
+          if (errorIndex == -1 && restartingNodeIndex == -1) {
+            // Not a datanode issue
             streamerClosed = true;
           }
         }
@@ -694,6 +705,65 @@ public class DFSOutputStream extends FSOutputSummer
       }
     }
 
+    // The following synchronized methods are used whenever 
+    // errorIndex or restartingNodeIndex is set. This is because
+    // check & set needs to be atomic. Simply reading variables
+    // does not require a synchronization. When responder is
+    // not running (e.g. during pipeline recovery), there is no
+    // need to use these methods.
+
+    /** Set the error node index. Called by responder */
+    synchronized void setErrorIndex(int idx) {
+      errorIndex = idx;
+    }
+
+    /** Set the restarting node index. Called by responder */
+    synchronized void setRestartingNodeIndex(int idx) {
+      restartingNodeIndex = idx;
+      // If the data streamer has already set the primary node
+      // bad, clear it. It is likely that the write failed due to
+      // the DN shutdown. Even if it was a real failure, the pipeline
+      // recovery will take care of it.
+      errorIndex = -1;      
+    }
+
+    /**
+     * This method is used when no explicit error report was received,
+     * but something failed. When the primary node is a suspect or
+     * unsure about the cause, the primary node is marked as failed.
+     */
+    synchronized void tryMarkPrimaryDatanodeFailed() {
+      // There should be no existing error and no ongoing restart.
+      if ((errorIndex == -1) && (restartingNodeIndex == -1)) {
+        errorIndex = 0;
+      }
+    }
+
+    /**
+     * Examine whether it is worth waiting for a node to restart.
+     * @param index the node index
+     */
+    boolean shouldWaitForRestart(int index) {
+      // Only one node in the pipeline.
+      if (nodes.length == 1) {
+        return true;
+      }
+
+      // Is it a local node?
+      InetAddress addr = null;
+      try {
+        addr = InetAddress.getByName(nodes[index].getIpAddr());
+      } catch (java.net.UnknownHostException e) {
+        // we are passing an ip address. this should not happen.
+        assert false;
+      }
+
+      if (addr != null && NetUtils.isLocalAddress(addr)) {
+        return true;
+      }
+      return false;
+    }
+
     //
     // Processes responses from the datanodes.  A packet is removed
     // from the ackQueue when its response arrives.
@@ -727,8 +797,20 @@ public class DFSOutputStream extends FSOutputSummer
             // processes response status from datanodes.
             for (int i = ack.getNumOfReplies()-1; i >=0  && dfsClient.clientRunning; i--) {
               final Status reply = ack.getReply(i);
+              // Restart will not be treated differently unless it is
+              // the local node or the only one in the pipeline.
+              if (PipelineAck.isRestartOOBStatus(reply) &&
+                  shouldWaitForRestart(i)) {
+                restartDeadline = dfsClient.getConf().datanodeRestartTimeout +
+                    Time.now();
+                setRestartingNodeIndex(i);
+                String message = "A datanode is restarting: " + targets[i];
+                DFSClient.LOG.info(message);
+               throw new IOException(message);
+              }
+              // node error
               if (reply != SUCCESS) {
-                errorIndex = i; // first bad datanode
+                setErrorIndex(i); // first bad datanode
                 throw new IOException("Bad response " + reply +
                     " for block " + block +
                     " from datanode " + 
@@ -777,12 +859,16 @@ public class DFSOutputStream extends FSOutputSummer
                 setLastException((IOException)e);
               }
               hasError = true;
-              errorIndex = errorIndex==-1 ? 0 : errorIndex;
+              // If no explicit error report was received, mark the primary
+              // node as failed.
+              tryMarkPrimaryDatanodeFailed();
               synchronized (dataQueue) {
                 dataQueue.notifyAll();
               }
-              DFSClient.LOG.warn("DFSOutputStream ResponseProcessor exception "
-                  + " for block " + block, e);
+              if (restartingNodeIndex == -1) {
+                DFSClient.LOG.warn("DFSOutputStream ResponseProcessor exception "
+                     + " for block " + block, e);
+              }
               responderClosed = true;
             }
           }
@@ -1001,6 +1087,24 @@ public class DFSOutputStream extends FSOutputSummer
       boolean success = false;
       long newGS = 0L;
       while (!success && !streamerClosed && dfsClient.clientRunning) {
+        // Sleep before reconnect if a dn is restarting.
+        // This process will be repeated until the deadline or the datanode
+        // starts back up.
+        if (restartingNodeIndex >= 0) {
+          // 4 seconds or the configured deadline period, whichever is shorter.
+          // This is the retry interval and recovery will be retried in this
+          // interval until timeout or success.
+          long delay = Math.min(dfsClient.getConf().datanodeRestartTimeout,
+              4000L);
+          try {
+            Thread.sleep(delay);
+          } catch (InterruptedException ie) {
+            lastException.set(new IOException("Interrupted while waiting for " +
+                "datanode to restart. " + nodes[restartingNodeIndex]));
+            streamerClosed = true;
+            return false;
+          }
+        }
         boolean isRecovery = hasError;
         // remove bad datanode from list of datanodes.
         // If errorIndex was not set (i.e. appends), then do not remove 
@@ -1037,7 +1141,24 @@ public class DFSOutputStream extends FSOutputSummer
           
           setPipeline(newnodes, newStorageIDs);
 
-          hasError = false;
+          // Just took care of a node error while waiting for a node restart
+          if (restartingNodeIndex >= 0) {
+            // If the error came from a node further away than the restarting
+            // node, the restart must have been complete.
+            if (errorIndex > restartingNodeIndex) {
+              restartingNodeIndex = -1;
+            } else if (errorIndex < restartingNodeIndex) {
+              // the node index has shifted.
+              restartingNodeIndex--;
+            } else {
+              // this shouldn't happen...
+              assert false;
+            }
+          }
+
+          if (restartingNodeIndex == -1) {
+            hasError = false;
+          }
           lastException.set(null);
           errorIndex = -1;
         }
@@ -1066,7 +1187,34 @@ public class DFSOutputStream extends FSOutputSummer
         } else {
           success = createBlockOutputStream(nodes, newGS, isRecovery);
         }
-      }
+
+        if (restartingNodeIndex >= 0) {
+          assert hasError == true;
+          // check errorIndex set above
+          if (errorIndex == restartingNodeIndex) {
+            // ignore, if came from the restarting node
+            errorIndex = -1;
+          }
+          // still within the deadline
+          if (Time.now() < restartDeadline) {
+            continue; // with in the deadline
+          }
+          // expired. declare the restarting node dead
+          restartDeadline = 0;
+          int expiredNodeIndex = restartingNodeIndex;
+          restartingNodeIndex = -1;
+          DFSClient.LOG.warn("Datanode did not restart in time: " +
+              nodes[expiredNodeIndex]);
+          // Mark the restarting node as failed. If there is any other failed
+          // node during the last pipeline construction attempt, it will not be
+          // overwritten/dropped. In this case, the restarting node will get
+          // excluded in the following attempt, if it still does not come up.
+          if (errorIndex == -1) {
+            errorIndex = expiredNodeIndex;
+          }
+          // From this point on, normal pipeline recovery applies.
+        }
+      } // while
 
       if (success) {
         // update pipeline at the namenode
@@ -1144,6 +1292,7 @@ public class DFSOutputStream extends FSOutputSummer
       }
       Status pipelineStatus = SUCCESS;
       String firstBadLink = "";
+      boolean checkRestart = false;
       if (DFSClient.LOG.isDebugEnabled()) {
         for (int i = 0; i < nodes.length; i++) {
           DFSClient.LOG.debug("pipeline = " + nodes[i]);
@@ -1192,6 +1341,16 @@ public class DFSOutputStream extends FSOutputSummer
           pipelineStatus = resp.getStatus();
           firstBadLink = resp.getFirstBadLink();
           
+          // Got an restart OOB ack.
+          // If a node is already restarting, this status is not likely from
+          // the same node. If it is from a different node, it is not
+          // from the local datanode. Thus it is safe to treat this as a
+          // regular node error.
+          if (PipelineAck.isRestartOOBStatus(pipelineStatus) &&
+            restartingNodeIndex == -1) {
+            checkRestart = true;
+            throw new IOException("A datanode is restarting.");
+          }
           if (pipelineStatus != SUCCESS) {
             if (pipelineStatus == Status.ERROR_ACCESS_TOKEN) {
               throw new InvalidBlockTokenException(
@@ -1205,9 +1364,12 @@ public class DFSOutputStream extends FSOutputSummer
           assert null == blockStream : "Previous blockStream unclosed";
           blockStream = out;
           result =  true; // success
-  
+          restartingNodeIndex = -1;
+          hasError = false;
         } catch (IOException ie) {
-          DFSClient.LOG.info("Exception in createBlockOutputStream", ie);
+          if (restartingNodeIndex == -1) {
+            DFSClient.LOG.info("Exception in createBlockOutputStream", ie);
+          }
           if (ie instanceof InvalidEncryptionKeyException && refetchEncryptionKey > 0) {
             DFSClient.LOG.info("Will fetch a new encryption key and retry, " 
                 + "encryption key was invalid when connecting to "
@@ -1230,8 +1392,18 @@ public class DFSOutputStream extends FSOutputSummer
               }
             }
           } else {
+            assert checkRestart == false;
             errorIndex = 0;
           }
+          // Check whether there is a restart worth waiting for.
+          if (checkRestart && shouldWaitForRestart(errorIndex)) {
+            restartDeadline = dfsClient.getConf().datanodeRestartTimeout +
+                Time.now();
+            restartingNodeIndex = errorIndex;
+            errorIndex = -1;
+            DFSClient.LOG.info("Waiting for the datanode to be restarted: " +
+                nodes[restartingNodeIndex]);
+          }
           hasError = true;
           setLastException(ie);
           result =  false;  // error

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DistributedFileSystem.java

@@ -61,6 +61,7 @@ import org.apache.hadoop.hdfs.client.HdfsAdmin;
 import org.apache.hadoop.hdfs.client.HdfsDataInputStream;
 import org.apache.hadoop.hdfs.client.HdfsDataOutputStream;
 import org.apache.hadoop.hdfs.protocol.CacheDirectiveEntry;
+import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
 import org.apache.hadoop.hdfs.protocol.CachePoolEntry;
 import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
@@ -68,11 +69,12 @@ import org.apache.hadoop.hdfs.protocol.DirectoryListing;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.RollingUpgradeAction;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.HdfsLocatedFileStatus;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
-import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeInfo;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
 import org.apache.hadoop.hdfs.security.token.block.InvalidBlockTokenException;
@@ -993,6 +995,14 @@ public class DistributedFileSystem extends FileSystem {
     dfs.finalizeUpgrade();
   }
 
+  /**
+   * Rolling upgrade: start/finalize/query.
+   */
+  public RollingUpgradeInfo rollingUpgrade(RollingUpgradeAction action)
+      throws IOException {
+    return dfs.rollingUpgrade(action);
+  }
+
   /*
    * Requests the namenode to dump data strcutures into specified 
    * file.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/ClientDatanodeProtocol.java

@@ -125,4 +125,22 @@ public interface ClientDatanodeProtocol {
    */
   HdfsBlocksMetadata getHdfsBlocksMetadata(String blockPoolId,
       long []blockIds, List<Token<BlockTokenIdentifier>> tokens) throws IOException; 
+
+  /**
+   * Shuts down a datanode.
+   *
+   * @param forUpgrade If true, data node does extra prep work before shutting
+   *          down. The work includes advising clients to wait and saving
+   *          certain states for quick restart. This should only be used when
+   *          the stored data will remain the same during upgrade/restart.
+   * @throws IOException 
+   */
+  void shutdownDatanode(boolean forUpgrade) throws IOException;  
+
+  /**
+   * Obtains datanode info
+   *
+   * @return software/config version and uptime of the datanode
+   */
+  DatanodeLocalInfo getDatanodeInfo() throws IOException;
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/ClientProtocol.java

@@ -39,6 +39,7 @@ import org.apache.hadoop.fs.permission.AclEntry;
 import org.apache.hadoop.fs.permission.AclStatus;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.RollingUpgradeAction;
 import org.apache.hadoop.hdfs.security.token.block.DataEncryptionKey;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenSelector;
@@ -763,6 +764,15 @@ public interface ClientProtocol {
   @Idempotent
   public void finalizeUpgrade() throws IOException;
 
+  /**
+   * Rolling upgrade operations.
+   * @param action either query, start or finailze.
+   * @return rolling upgrade information.
+   */
+  @Idempotent
+  public RollingUpgradeInfo rollingUpgrade(RollingUpgradeAction action)
+      throws IOException;
+
   /**
    * @return CorruptFileBlocks, containing a list of corrupt files (with
    *         duplicates if there is more than one corrupt block in a file)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/DatanodeLocalInfo.java

@@ -0,0 +1,64 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.protocol;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+
+/**
+ * Locally available datanode information
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public class DatanodeLocalInfo {
+  private String softwareVersion;
+  private String configVersion;
+  private long uptime; // datanode uptime in seconds.
+
+  public DatanodeLocalInfo(String softwareVersion,
+      String configVersion, long uptime) {
+    this.softwareVersion = softwareVersion;
+    this.configVersion = configVersion;
+    this.uptime = uptime;
+  }
+
+  /** get software version */
+  public String getSoftwareVersion() {
+    return this.softwareVersion;
+  }
+
+  /** get config version */
+  public String getConfigVersion() {
+    return this.configVersion;
+  }
+
+  /** get uptime */
+  public long getUptime() {
+    return this.uptime;
+  }
+
+  /** A formatted string for printing the status of the DataNode. */
+  public String getDatanodeLocalReport() {
+    StringBuilder buffer = new StringBuilder();
+    buffer.append("Uptime: " + getUptime());
+    buffer.append(", Software version: " + getSoftwareVersion());
+    buffer.append(", Config version: " + getConfigVersion());
+    return buffer.toString();
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/HdfsConstants.java

@@ -17,11 +17,16 @@
  */
 package org.apache.hadoop.hdfs.protocol;
 
+import java.util.HashMap;
+import java.util.Map;
+
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.DFSUtil;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
+import org.apache.hadoop.hdfs.server.datanode.DataNodeLayoutVersion;
+import org.apache.hadoop.hdfs.server.namenode.NameNodeLayoutVersion;
 import org.apache.hadoop.hdfs.server.namenode.FSDirectory;
 
 /************************************
@@ -79,6 +84,24 @@ public class HdfsConstants {
     SAFEMODE_LEAVE, SAFEMODE_ENTER, SAFEMODE_GET;
   }
 
+  public static enum RollingUpgradeAction {
+    QUERY, PREPARE, FINALIZE;
+    
+    private static final Map<String, RollingUpgradeAction> MAP
+        = new HashMap<String, RollingUpgradeAction>();
+    static {
+      MAP.put("", QUERY);
+      for(RollingUpgradeAction a : values()) {
+        MAP.put(a.name(), a);
+      }
+    }
+
+    /** Covert the given String to a RollingUpgradeAction. */
+    public static RollingUpgradeAction fromString(String s) {
+      return MAP.get(s.toUpperCase());
+    }
+  }
+
   // type of the datanode report
   public static enum DatanodeReportType {
     ALL, LIVE, DEAD
@@ -105,10 +128,18 @@ public class HdfsConstants {
 
 
   /**
-   * Please see {@link LayoutVersion} on adding new layout version.
+   * Current layout version for NameNode.
+   * Please see {@link NameNodeLayoutVersion.Feature} on adding new layout version.
+   */
+  public static final int NAMENODE_LAYOUT_VERSION
+      = NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION;
+
+  /**
+   * Current layout version for DataNode.
+   * Please see {@link DataNodeLayoutVersion.Feature} on adding new layout version.
    */
-  public static final int LAYOUT_VERSION = LayoutVersion
-      .getCurrentLayoutVersion();
+  public static final int DATANODE_LAYOUT_VERSION
+      = DataNodeLayoutVersion.CURRENT_LAYOUT_VERSION;
 
   /**
    * Path components that are reserved in HDFS.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/LayoutVersion.java

@@ -17,9 +17,10 @@
  */
 package org.apache.hadoop.hdfs.protocol;
 
-import java.util.EnumSet;
-import java.util.HashMap;
+import java.util.Comparator;
 import java.util.Map;
+import java.util.SortedSet;
+import java.util.TreeSet;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 
@@ -43,7 +44,6 @@ import org.apache.hadoop.classification.InterfaceAudience;
  */
 @InterfaceAudience.Private
 public class LayoutVersion {
- 
   /**
    * Version in which HDFS-2991 was fixed. This bug caused OP_ADD to
    * sometimes be skipped for append() calls. If we see such a case when
@@ -54,19 +54,27 @@ public class LayoutVersion {
   public static final int BUGFIX_HDFS_2991_VERSION = -40;
 
   /**
-   * Enums for features that change the layout version.
+   * The interface to be implemented by NameNode and DataNode layout features 
+   */
+  public interface LayoutFeature {
+    public FeatureInfo getInfo();
+  }
+
+  /**
+   * Enums for features that change the layout version before rolling
+   * upgrade is supported.
    * <br><br>
    * To add a new layout version:
    * <ul>
    * <li>Define a new enum constant with a short enum name, the new layout version 
    * and description of the added feature.</li>
    * <li>When adding a layout version with an ancestor that is not same as
-   * its immediate predecessor, use the constructor where a spacific ancestor
+   * its immediate predecessor, use the constructor where a specific ancestor
    * can be passed.
    * </li>
    * </ul>
    */
-  public static enum Feature {
+  public static enum Feature implements LayoutFeature {
     NAMESPACE_QUOTA(-16, "Support for namespace quotas"),
     FILE_ACCESS_TIME(-17, "Support for access time on files"),
     DISKSPACE_QUOTA(-18, "Support for disk space quotas"),
@@ -119,12 +127,8 @@ public class LayoutVersion {
     RESERVED_REL2_4_0(-54, -51, "Reserved for release 2.4.0", true,
         PROTOBUF_FORMAT, EXTENDED_ACL);
 
-    final int lv;
-    final int ancestorLV;
-    final String description;
-    final boolean reserved;
-    final Feature[] specialFeatures;
-    
+    private final FeatureInfo info;
+
     /**
      * Feature that is added at layout version {@code lv} - 1. 
      * @param lv new layout version with the addition of this feature
@@ -140,16 +144,35 @@ public class LayoutVersion {
      * @param ancestorLV layout version from which the new lv is derived from.
      * @param description description of the feature
      * @param reserved true when this is a layout version reserved for previous
-     *          verions
+     *        version
      * @param features set of features that are to be enabled for this version
      */
     Feature(final int lv, final int ancestorLV, final String description,
         boolean reserved, Feature... features) {
+      info = new FeatureInfo(lv, ancestorLV, description, reserved, features);
+    }
+    
+    @Override
+    public FeatureInfo getInfo() {
+      return info;
+    }
+  }
+  
+  /** Feature information. */
+  public static class FeatureInfo {
+    private final int lv;
+    private final int ancestorLV;
+    private final String description;
+    private final boolean reserved;
+    private final LayoutFeature[] specialFeatures;
+
+    public FeatureInfo(final int lv, final int ancestorLV, final String description,
+        boolean reserved, LayoutFeature... specialFeatures) {
       this.lv = lv;
       this.ancestorLV = ancestorLV;
       this.description = description;
       this.reserved = reserved;
-      specialFeatures = features;
+      this.specialFeatures = specialFeatures;
     }
     
     /** 
@@ -179,80 +202,91 @@ public class LayoutVersion {
     public boolean isReservedForOldRelease() {
       return reserved;
     }
+    
+    public LayoutFeature[] getSpecialFeatures() {
+      return specialFeatures;
+    }
   }
-  
-  // Build layout version and corresponding feature matrix
-  static final Map<Integer, EnumSet<Feature>>map = 
-    new HashMap<Integer, EnumSet<Feature>>();
-  
-  // Static initialization 
-  static {
-    initMap();
+
+  static class LayoutFeatureComparator implements Comparator<LayoutFeature> {
+    @Override
+    public int compare(LayoutFeature arg0, LayoutFeature arg1) {
+      return arg0.getInfo().getLayoutVersion()
+          - arg1.getInfo().getLayoutVersion();
+    }
   }
-  
-  /**
-   * Initialize the map of a layout version and EnumSet of {@link Feature}s 
-   * supported.
-   */
-  private static void initMap() {
+ 
+  public static void updateMap(Map<Integer, SortedSet<LayoutFeature>> map,
+      LayoutFeature[] features) {
     // Go through all the enum constants and build a map of
-    // LayoutVersion <-> EnumSet of all supported features in that LayoutVersion
-    for (Feature f : Feature.values()) {
-      EnumSet<Feature> ancestorSet = map.get(f.ancestorLV);
+    // LayoutVersion <-> Set of all supported features in that LayoutVersion
+    for (LayoutFeature f : features) {
+      final FeatureInfo info = f.getInfo();
+      SortedSet<LayoutFeature> ancestorSet = map.get(info.getAncestorLayoutVersion());
       if (ancestorSet == null) {
-        ancestorSet = EnumSet.noneOf(Feature.class); // Empty enum set
-        map.put(f.ancestorLV, ancestorSet);
+        // Empty set
+        ancestorSet = new TreeSet<LayoutFeature>(new LayoutFeatureComparator());
+        map.put(info.getAncestorLayoutVersion(), ancestorSet);
       }
-      EnumSet<Feature> featureSet = EnumSet.copyOf(ancestorSet);
-      if (f.specialFeatures != null) {
-        for (Feature specialFeature : f.specialFeatures) {
+      SortedSet<LayoutFeature> featureSet = new TreeSet<LayoutFeature>(ancestorSet);
+      if (info.getSpecialFeatures() != null) {
+        for (LayoutFeature specialFeature : info.getSpecialFeatures()) {
           featureSet.add(specialFeature);
         }
       }
       featureSet.add(f);
-      map.put(f.lv, featureSet);
+      map.put(info.getLayoutVersion(), featureSet);
     }
   }
   
   /**
    * Gets formatted string that describes {@link LayoutVersion} information.
    */
-  public static String getString() {
+  public String getString(Map<Integer, SortedSet<LayoutFeature>> map,
+      LayoutFeature[] values) {
     final StringBuilder buf = new StringBuilder();
     buf.append("Feature List:\n");
-    for (Feature f : Feature.values()) {
+    for (LayoutFeature f : values) {
+      final FeatureInfo info = f.getInfo();
       buf.append(f).append(" introduced in layout version ")
-          .append(f.lv).append(" (").
-      append(f.description).append(")\n");
+          .append(info.getLayoutVersion()).append(" (")
+          .append(info.getDescription()).append(")\n");
     }
-    
+
     buf.append("\n\nLayoutVersion and supported features:\n");
-    for (Feature f : Feature.values()) {
-      buf.append(f.lv).append(": ").append(map.get(f.lv))
-          .append("\n");
+    for (LayoutFeature f : values) {
+      final FeatureInfo info = f.getInfo();
+      buf.append(info.getLayoutVersion()).append(": ")
+          .append(map.get(info.getLayoutVersion())).append("\n");
     }
     return buf.toString();
   }
   
   /**
    * Returns true if a given feature is supported in the given layout version
+   * @param map layout feature map
    * @param f Feature
    * @param lv LayoutVersion
    * @return true if {@code f} is supported in layout version {@code lv}
    */
-  public static boolean supports(final Feature f, final int lv) {
-    final EnumSet<Feature> set =  map.get(lv);
+  public static boolean supports(Map<Integer, SortedSet<LayoutFeature>> map,
+      final LayoutFeature f, final int lv) {
+    final SortedSet<LayoutFeature> set =  map.get(lv);
     return set != null && set.contains(f);
   }
   
   /**
    * Get the current layout version
    */
-  public static int getCurrentLayoutVersion() {
-    Feature[] values = Feature.values();
-    for (int i = values.length -1; i >= 0; i--) {
-      if (!values[i].isReservedForOldRelease()) {
-        return values[i].lv;
+  public static int getCurrentLayoutVersion(LayoutFeature[] features) {
+    return getLastNonReservedFeature(features).getInfo().getLayoutVersion();
+  }
+
+  static LayoutFeature getLastNonReservedFeature(LayoutFeature[] features) {
+    for (int i = features.length -1; i >= 0; i--) {
+      final FeatureInfo info = features[i].getInfo();
+      if (!info.isReservedForOldRelease()) {
+        return features[i];
       }
     }
     throw new AssertionError("All layout versions are reserved.");

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/RollingUpgradeException.java

@@ -0,0 +1,36 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.protocol;
+
+import java.io.IOException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/**
+ * Exception related to rolling upgrade.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public class RollingUpgradeException extends IOException {
+  private static final long serialVersionUID = 1L;
+
+  public RollingUpgradeException(String msg) {
+    super(msg);
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/RollingUpgradeInfo.java

@@ -0,0 +1,127 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.protocol;
+
+import java.util.Date;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/**
+ * Rolling upgrade information
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public class RollingUpgradeInfo extends RollingUpgradeStatus {
+  private final long startTime;
+  private final long finalizeTime;
+  private boolean createdRollbackImages;
+  
+  public RollingUpgradeInfo(String blockPoolId, boolean createdRollbackImages,
+      long startTime, long finalizeTime) {
+    super(blockPoolId);
+    this.createdRollbackImages = createdRollbackImages;
+    this.startTime = startTime;
+    this.finalizeTime = finalizeTime;
+  }
+  
+  public boolean createdRollbackImages() {
+    return createdRollbackImages;
+  }
+
+  public void setCreatedRollbackImages(boolean created) {
+    this.createdRollbackImages = created;
+  }
+
+  public boolean isStarted() {
+    return startTime != 0;
+  }
+  
+  /** @return The rolling upgrade starting time. */
+  public long getStartTime() {
+    return startTime;
+  }
+  
+  public boolean isFinalized() {
+    return finalizeTime != 0;
+  }
+
+  public long getFinalizeTime() {
+    return finalizeTime;
+  }
+
+  @Override
+  public int hashCode() {
+    //only use lower 32 bits
+    return super.hashCode() ^ (int)startTime ^ (int)finalizeTime;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (obj == this) {
+      return true;
+    } else if (obj == null || !(obj instanceof RollingUpgradeInfo)) {
+      return false;
+    }
+    final RollingUpgradeInfo that = (RollingUpgradeInfo)obj;
+    return super.equals(that)
+        && this.startTime == that.startTime
+        && this.finalizeTime == that.finalizeTime;
+  }
+
+  @Override
+  public String toString() {
+    return super.toString()
+      +  "\n     Start Time: " + (startTime == 0? "<NOT STARTED>": timestamp2String(startTime))
+      +  "\n  Finalize Time: " + (finalizeTime == 0? "<NOT FINALIZED>": timestamp2String(finalizeTime));
+  }
+  
+  private static String timestamp2String(long timestamp) {
+    return new Date(timestamp) + " (=" + timestamp + ")";
+  }
+
+  public static class Bean {
+    private final String blockPoolId;
+    private final long startTime;
+    private final long finalizeTime;
+    private final boolean createdRollbackImages;
+
+    public Bean(RollingUpgradeInfo f) {
+      this.blockPoolId = f.getBlockPoolId();
+      this.startTime = f.startTime;
+      this.finalizeTime = f.finalizeTime;
+      this.createdRollbackImages = f.createdRollbackImages();
+    }
+
+    public String getBlockPoolId() {
+      return blockPoolId;
+    }
+
+    public long getStartTime() {
+      return startTime;
+    }
+
+    public long getFinalizeTime() {
+      return finalizeTime;
+    }
+
+    public boolean isCreatedRollbackImages() {
+      return createdRollbackImages;
+    }
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/RollingUpgradeStatus.java

@@ -0,0 +1,59 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.protocol;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/**
+ * Rolling upgrade status
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Evolving
+public class RollingUpgradeStatus {
+  private String blockPoolId;
+
+  public RollingUpgradeStatus(String blockPoolId) {
+    this.blockPoolId = blockPoolId;
+  }
+
+  public String getBlockPoolId() {
+    return blockPoolId;
+  }
+
+  @Override
+  public int hashCode() {
+    return blockPoolId.hashCode();
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (obj == this) {
+      return true;
+    } else if (obj == null || !(obj instanceof RollingUpgradeStatus)) {
+      return false;
+    }
+    final RollingUpgradeStatus that = (RollingUpgradeStatus)obj;
+    return this.blockPoolId.equals(that.blockPoolId);
+  }
+
+  @Override
+  public String toString() {
+    return "  Block Pool ID: " + blockPoolId;
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/PipelineAck.java

@@ -26,10 +26,12 @@ import java.util.Arrays;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.hdfs.HdfsConfiguration;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_OOB_TIMEOUT_KEY;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_OOB_TIMEOUT_DEFAULT;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.PipelineAckProto;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.Status;
-
 import com.google.protobuf.TextFormat;
 
 /** Pipeline Acknowledgment **/
@@ -38,6 +40,21 @@ import com.google.protobuf.TextFormat;
 public class PipelineAck {
   PipelineAckProto proto;
   public final static long UNKOWN_SEQNO = -2;
+  final static int OOB_START = Status.OOB_RESTART_VALUE; // the first OOB type
+  final static int OOB_END = Status.OOB_RESERVED3_VALUE; // the last OOB type
+  final static int NUM_OOB_TYPES = OOB_END - OOB_START + 1;
+  // place holder for timeout value of each OOB type
+  final static long[] OOB_TIMEOUT;
+
+  static {
+    OOB_TIMEOUT = new long[NUM_OOB_TYPES];
+    HdfsConfiguration conf = new HdfsConfiguration();
+    String[] ele = conf.get(DFS_DATANODE_OOB_TIMEOUT_KEY,
+        DFS_DATANODE_OOB_TIMEOUT_DEFAULT).split(",");
+    for (int i = 0; i < NUM_OOB_TYPES; i++) {
+      OOB_TIMEOUT[i] = (i < ele.length) ? Long.valueOf(ele[i]) : 0;
+    }
+  }
 
   /** default constructor **/
   public PipelineAck() {
@@ -103,14 +120,57 @@ public class PipelineAck {
    * @return true if all statuses are SUCCESS
    */
   public boolean isSuccess() {
-    for (DataTransferProtos.Status reply : proto.getStatusList()) {
-      if (reply != DataTransferProtos.Status.SUCCESS) {
+    for (Status reply : proto.getStatusList()) {
+      if (reply != Status.SUCCESS) {
         return false;
       }
     }
     return true;
   }
-  
+
+  /**
+   * Returns the OOB status if this ack contains one. 
+   * @return null if it is not an OOB ack.
+   */
+  public Status getOOBStatus() {
+    // Normal data transfer acks will have a valid sequence number, so
+    // this will return right away in most cases.
+    if (getSeqno() != UNKOWN_SEQNO) {
+      return null;
+    }
+    for (Status reply : proto.getStatusList()) {
+      // The following check is valid because protobuf guarantees to
+      // preserve the ordering of enum elements.
+      if (reply.getNumber() >= OOB_START && reply.getNumber() <= OOB_END) {
+        return reply;
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Get the timeout to be used for transmitting the OOB type
+   * @return the timeout in milliseconds
+   */
+  public static long getOOBTimeout(Status status) throws IOException {
+    int index = status.getNumber() - OOB_START;
+    if (index >= 0 && index < NUM_OOB_TYPES) {
+      return OOB_TIMEOUT[index];
+    } 
+    // Not an OOB.
+    throw new IOException("Not an OOB status: " + status);
+  }
+
+  /** Get the Restart OOB ack status */
+  public static Status getRestartOOBStatus() {
+    return Status.OOB_RESTART;
+  }
+
+  /** return true if it is the restart OOB status code  */
+  public static boolean isRestartOOBStatus(Status st) {
+    return st.equals(Status.OOB_RESTART);
+  }
+
   /**** Writable interface ****/
   public void readFields(InputStream in) throws IOException {
     proto = PipelineAckProto.parseFrom(vintPrefixed(in));

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/ClientDatanodeProtocolServerSideTranslatorPB.java

@@ -30,6 +30,8 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.Delete
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.DeleteBlockPoolResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetBlockLocalPathInfoRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetBlockLocalPathInfoResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetDatanodeInfoRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetDatanodeInfoResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetHdfsBlockLocationsRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetHdfsBlockLocationsResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetHdfsBlockLocationsResponseProto.Builder;
@@ -37,10 +39,13 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetRep
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetReplicaVisibleLengthResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.RefreshNamenodesRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.RefreshNamenodesResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.ShutdownDatanodeRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.ShutdownDatanodeResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.ExtendedBlockProto;
 import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
 import org.apache.hadoop.security.proto.SecurityProtos.TokenProto;
 import org.apache.hadoop.security.token.Token;
+import org.apache.hadoop.util.VersionInfo;
 
 import com.google.common.primitives.Longs;
 import com.google.protobuf.ByteString;
@@ -59,6 +64,8 @@ public class ClientDatanodeProtocolServerSideTranslatorPB implements
       RefreshNamenodesResponseProto.newBuilder().build();
   private final static DeleteBlockPoolResponseProto DELETE_BLOCKPOOL_RESP =
       DeleteBlockPoolResponseProto.newBuilder().build();
+  private final static ShutdownDatanodeResponseProto SHUTDOWN_DATANODE_RESP =
+      ShutdownDatanodeResponseProto.newBuilder().build();
   
   private final ClientDatanodeProtocol impl;
 
@@ -151,4 +158,28 @@ public class ClientDatanodeProtocolServerSideTranslatorPB implements
     builder.addAllVolumeIndexes(resp.getVolumeIndexes());
     return builder.build();
   }
+
+  @Override
+  public ShutdownDatanodeResponseProto shutdownDatanode(
+      RpcController unused, ShutdownDatanodeRequestProto request)
+      throws ServiceException {
+    try {
+      impl.shutdownDatanode(request.getForUpgrade());
+    } catch (IOException e) {
+      throw new ServiceException(e);
+    }
+    return SHUTDOWN_DATANODE_RESP;
+  }
+
+  public GetDatanodeInfoResponseProto getDatanodeInfo(RpcController unused,
+      GetDatanodeInfoRequestProto request) throws ServiceException {
+    GetDatanodeInfoResponseProto res;
+    try {
+      res = GetDatanodeInfoResponseProto.newBuilder()
+          .setLocalInfo(PBHelper.convert(impl.getDatanodeInfo())).build();
+    } catch (IOException e) {
+      throw new ServiceException(e);
+    }
+    return res;
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/ClientDatanodeProtocolTranslatorPB.java

@@ -35,16 +35,20 @@ import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
 import org.apache.hadoop.hdfs.protocol.BlockLocalPathInfo;
 import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
 import org.apache.hadoop.hdfs.protocol.DatanodeID;
+import org.apache.hadoop.hdfs.protocol.DatanodeLocalInfo;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsBlocksMetadata;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.DeleteBlockPoolRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetBlockLocalPathInfoRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetBlockLocalPathInfoResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetDatanodeInfoRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetDatanodeInfoResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetHdfsBlockLocationsRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetHdfsBlockLocationsResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.GetReplicaVisibleLengthRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.RefreshNamenodesRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.ShutdownDatanodeRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.ExtendedBlockProto;
 import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
 import org.apache.hadoop.ipc.ProtobufHelper;
@@ -81,6 +85,8 @@ public class ClientDatanodeProtocolTranslatorPB implements
   private final ClientDatanodeProtocolPB rpcProxy;
   private final static RefreshNamenodesRequestProto VOID_REFRESH_NAMENODES = 
       RefreshNamenodesRequestProto.newBuilder().build();
+  private final static GetDatanodeInfoRequestProto VOID_GET_DATANODE_INFO =
+      GetDatanodeInfoRequestProto.newBuilder().build();
 
   public ClientDatanodeProtocolTranslatorPB(DatanodeID datanodeid,
       Configuration conf, int socketTimeout, boolean connectToDnViaHostname,
@@ -253,4 +259,27 @@ public class ClientDatanodeProtocolTranslatorPB implements
     return new HdfsBlocksMetadata(blockPoolId, blockIds,
         volumeIds, volumeIndexes);
   }
+
+  @Override
+  public void shutdownDatanode(boolean forUpgrade) throws IOException {
+    ShutdownDatanodeRequestProto request = ShutdownDatanodeRequestProto
+        .newBuilder().setForUpgrade(forUpgrade).build();
+    try {
+      rpcProxy.shutdownDatanode(NULL_CONTROLLER, request);
+    } catch (ServiceException e) {
+      throw ProtobufHelper.getRemoteException(e);
+    }
+  }
+
+  @Override
+  public DatanodeLocalInfo getDatanodeInfo() throws IOException {
+    GetDatanodeInfoResponseProto response;
+    try {
+      response = rpcProxy.getDatanodeInfo(NULL_CONTROLLER, VOID_GET_DATANODE_INFO);
+      return PBHelper.convert(response.getLocalInfo());
+    } catch (ServiceException e) {
+      throw ProtobufHelper.getRemoteException(e);
+    }
+  }
+
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/ClientNamenodeProtocolServerSideTranslatorPB.java

@@ -22,11 +22,12 @@ import java.util.List;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.fs.BatchedRemoteIterator.BatchedEntries;
 import org.apache.hadoop.fs.ContentSummary;
 import org.apache.hadoop.fs.FsServerDefaults;
-import org.apache.hadoop.fs.BatchedRemoteIterator.BatchedEntries;
 import org.apache.hadoop.fs.Options.Rename;
 import org.apache.hadoop.hdfs.protocol.CacheDirectiveEntry;
+import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
 import org.apache.hadoop.hdfs.protocol.CachePoolEntry;
 import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.hdfs.protocol.CorruptFileBlocks;
@@ -34,7 +35,7 @@ import org.apache.hadoop.hdfs.protocol.DirectoryListing;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
-import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeInfo;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
 import org.apache.hadoop.hdfs.protocol.proto.AclProtos.GetAclStatusRequestProto;
@@ -53,10 +54,10 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.Abando
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AbandonBlockResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddBlockRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddBlockResponseProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddCachePoolRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddCachePoolResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddCacheDirectiveRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddCacheDirectiveResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddCachePoolRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddCachePoolResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AllowSnapshotRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AllowSnapshotResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AppendRequestProto;
@@ -112,28 +113,28 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetSna
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetSnapshottableDirListingResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.IsFileClosedRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.IsFileClosedResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCacheDirectivesRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCacheDirectivesResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCachePoolsRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCachePoolsResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCorruptFileBlocksRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCorruptFileBlocksResponseProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCacheDirectivesRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCacheDirectivesResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.MetaSaveRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.MetaSaveResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.MkdirsRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.MkdirsResponseProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyCachePoolRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyCachePoolResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyCacheDirectiveRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyCacheDirectiveResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyCachePoolRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyCachePoolResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RecoverLeaseRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RecoverLeaseResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RefreshNodesRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RefreshNodesResponseProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemoveCachePoolRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemoveCachePoolResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemoveCacheDirectiveRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemoveCacheDirectiveResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemoveCachePoolRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemoveCachePoolResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.Rename2RequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.Rename2ResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RenameRequestProto;
@@ -148,6 +149,8 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.Restor
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RestoreFailedStorageResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RollEditsRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RollEditsResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RollingUpgradeRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RollingUpgradeResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.SaveNamespaceRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.SaveNamespaceResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.SetBalancerBandwidthRequestProto;
@@ -711,6 +714,22 @@ public class ClientNamenodeProtocolServerSideTranslatorPB implements
     }
   }
 
+  @Override
+  public RollingUpgradeResponseProto rollingUpgrade(RpcController controller,
+      RollingUpgradeRequestProto req) throws ServiceException {
+    try {
+      final RollingUpgradeInfo info = server.rollingUpgrade(
+          PBHelper.convert(req.getAction()));
+      final RollingUpgradeResponseProto.Builder b = RollingUpgradeResponseProto.newBuilder();
+      if (info != null) {
+        b.setRollingUpgradeInfo(PBHelper.convert(info));
+      }
+      return b.build();
+    } catch (IOException e) {
+      throw new ServiceException(e);
+    }
+  }
+
   @Override
   public ListCorruptFileBlocksResponseProto listCorruptFileBlocks(
       RpcController controller, ListCorruptFileBlocksRequestProto req)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/ClientNamenodeProtocolTranslatorPB.java

@@ -40,8 +40,9 @@ import org.apache.hadoop.fs.permission.AclStatus;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException;
 import org.apache.hadoop.hdfs.protocol.CacheDirectiveEntry;
-import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
+import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
 import org.apache.hadoop.hdfs.protocol.CachePoolEntry;
+import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
 import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.hdfs.protocol.CorruptFileBlocks;
 import org.apache.hadoop.hdfs.protocol.DSQuotaExceededException;
@@ -50,12 +51,13 @@ import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.DirectoryListing;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.RollingUpgradeAction;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
 import org.apache.hadoop.hdfs.protocol.NSQuotaExceededException;
-import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeInfo;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
 import org.apache.hadoop.hdfs.protocol.proto.AclProtos.GetAclStatusRequestProto;
@@ -66,8 +68,8 @@ import org.apache.hadoop.hdfs.protocol.proto.AclProtos.RemoveDefaultAclRequestPr
 import org.apache.hadoop.hdfs.protocol.proto.AclProtos.SetAclRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AbandonBlockRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddBlockRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddCachePoolRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddCacheDirectiveRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddCachePoolRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AllowSnapshotRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AppendRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AppendResponseProto;
@@ -106,19 +108,19 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetSna
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetSnapshottableDirListingRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetSnapshottableDirListingResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.IsFileClosedRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCacheDirectivesRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCacheDirectivesResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCachePoolsRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCachePoolsResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCorruptFileBlocksRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCacheDirectivesRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCacheDirectivesResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.MetaSaveRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.MkdirsRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyCachePoolRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyCacheDirectiveRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyCachePoolRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RecoverLeaseRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RefreshNodesRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemoveCachePoolRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemoveCacheDirectiveRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemoveCachePoolRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.Rename2RequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RenameRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RenameSnapshotRequestProto;
@@ -127,6 +129,8 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.Report
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RestoreFailedStorageRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RollEditsRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RollEditsResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RollingUpgradeRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RollingUpgradeResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.SaveNamespaceRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.SetBalancerBandwidthRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.SetOwnerRequestProto;
@@ -644,6 +648,21 @@ public class ClientNamenodeProtocolTranslatorPB implements
     }
   }
 
+  @Override
+  public RollingUpgradeInfo rollingUpgrade(RollingUpgradeAction action) throws IOException {
+    final RollingUpgradeRequestProto r = RollingUpgradeRequestProto.newBuilder()
+        .setAction(PBHelper.convert(action)).build();
+    try {
+      final RollingUpgradeResponseProto proto = rpcProxy.rollingUpgrade(null, r);
+      if (proto.hasRollingUpgradeInfo()) {
+        return PBHelper.convert(proto.getRollingUpgradeInfo());
+      }
+      return null;
+    } catch (ServiceException e) {
+      throw ProtobufHelper.getRemoteException(e);
+    }
+  }
+
   @Override
   public CorruptFileBlocks listCorruptFileBlocks(String path, String cookie)
       throws IOException {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/DatanodeProtocolClientSideTranslatorPB.java

@@ -34,6 +34,7 @@ import org.apache.hadoop.hdfs.protocol.DatanodeID;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeStatus;
 import org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos.BlockReceivedAndDeletedRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos.BlockReportRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos.BlockReportResponseProto;
@@ -184,7 +185,12 @@ public class DatanodeProtocolClientSideTranslatorPB implements
       cmds[index] = PBHelper.convert(p);
       index++;
     }
-    return new HeartbeatResponse(cmds, PBHelper.convert(resp.getHaStatus()));
+    RollingUpgradeStatus rollingUpdateStatus = null;
+    if (resp.hasRollingUpgradeStatus()) {
+      rollingUpdateStatus = PBHelper.convert(resp.getRollingUpgradeStatus());
+    }
+    return new HeartbeatResponse(cmds, PBHelper.convert(resp.getHaStatus()),
+        rollingUpdateStatus);
   }
 
   @Override

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/DatanodeProtocolServerSideTranslatorPB.java

@@ -23,6 +23,7 @@ import java.util.List;
 
 import org.apache.hadoop.hdfs.protocol.DatanodeID;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeStatus;
 import org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos.BlockReceivedAndDeletedRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos.BlockReceivedAndDeletedResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos.BlockReportRequestProto;
@@ -121,6 +122,12 @@ public class DatanodeProtocolServerSideTranslatorPB implements
       }
     }
     builder.setHaStatus(PBHelper.convert(response.getNameNodeHaState()));
+    RollingUpgradeStatus rollingUpdateStatus = response
+        .getRollingUpdateStatus();
+    if (rollingUpdateStatus != null) {
+      builder.setRollingUpgradeStatus(PBHelper
+          .convertRollingUpgradeStatus(rollingUpdateStatus));
+    }
     return builder.build();
   }
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/PBHelper.java

@@ -46,6 +46,7 @@ import org.apache.hadoop.hdfs.ShortCircuitShm.SlotId;
 import org.apache.hadoop.hdfs.StorageType;
 import org.apache.hadoop.hdfs.protocol.Block;
 import org.apache.hadoop.hdfs.protocol.CacheDirectiveEntry;
+import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
 import org.apache.hadoop.hdfs.protocol.CacheDirectiveStats;
 import org.apache.hadoop.hdfs.protocol.CachePoolEntry;
 import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
@@ -54,17 +55,20 @@ import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.hdfs.protocol.CorruptFileBlocks;
 import org.apache.hadoop.hdfs.protocol.DatanodeID;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
-import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
-import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo.AdminStates;
+import org.apache.hadoop.hdfs.protocol.DatanodeLocalInfo;
 import org.apache.hadoop.hdfs.protocol.DirectoryListing;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.RollingUpgradeAction;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.HdfsLocatedFileStatus;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeInfo;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeStatus;
+import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport.DiffReportEntry;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport.DiffType;
 import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
@@ -77,6 +81,7 @@ import org.apache.hadoop.hdfs.protocol.proto.AclProtos.GetAclStatusResponseProto
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.CacheDirectiveEntryProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.CacheDirectiveInfoExpirationProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.CacheDirectiveInfoProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.CacheDirectiveStatsProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.CacheFlagProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.CachePoolEntryProto;
@@ -85,8 +90,9 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.CacheP
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.CreateFlagProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.DatanodeReportTypeProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetFsStatsResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RollingUpgradeActionProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RollingUpgradeInfoProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.SafeModeActionProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.CacheDirectiveInfoProto;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.ShortCircuitShmSlotProto;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.ShortCircuitShmIdProto;
 import org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos.BalancerBandwidthCommandProto;
@@ -117,6 +123,7 @@ import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.DatanodeIDProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.DatanodeInfoProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.DatanodeInfoProto.AdminState;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.DatanodeInfosProto;
+import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.DatanodeLocalInfoProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.DirectoryListingProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.ExportedBlockKeysProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.ExtendedBlockProto;
@@ -135,6 +142,7 @@ import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.RecoveringBlockProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.RemoteEditLogManifestProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.RemoteEditLogProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.ReplicaStateProto;
+import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.RollingUpgradeStatusProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.SnapshotDiffReportEntryProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.SnapshotDiffReportProto;
 import org.apache.hadoop.hdfs.protocol.proto.HdfsProtos.SnapshottableDirectoryListingProto;
@@ -149,6 +157,7 @@ import org.apache.hadoop.hdfs.security.token.block.DataEncryptionKey;
 import org.apache.hadoop.hdfs.security.token.block.ExportedBlockKeys;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NamenodeRole;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NodeType;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.ReplicaState;
 import org.apache.hadoop.hdfs.server.common.StorageInfo;
 import org.apache.hadoop.hdfs.server.namenode.CheckpointSignature;
@@ -254,9 +263,9 @@ public class PBHelper {
         .setNamespceID(info.getNamespaceID()).build();
   }
 
-  public static StorageInfo convert(StorageInfoProto info) {
+  public static StorageInfo convert(StorageInfoProto info, NodeType type) {
     return new StorageInfo(info.getLayoutVersion(), info.getNamespceID(),
-        info.getClusterID(), info.getCTime());
+        info.getClusterID(), info.getCTime(), type);
   }
 
   public static NamenodeRegistrationProto convert(NamenodeRegistration reg) {
@@ -267,8 +276,9 @@ public class PBHelper {
   }
 
   public static NamenodeRegistration convert(NamenodeRegistrationProto reg) {
+    StorageInfo si = convert(reg.getStorageInfo(), NodeType.NAME_NODE);
     return new NamenodeRegistration(reg.getRpcAddress(), reg.getHttpAddress(),
-        convert(reg.getStorageInfo()), convert(reg.getRole()));
+        si, convert(reg.getRole()));
   }
 
   // DatanodeId
@@ -400,9 +410,9 @@ public class PBHelper {
   }
 
   public static CheckpointSignature convert(CheckpointSignatureProto s) {
-    return new CheckpointSignature(PBHelper.convert(s.getStorageInfo()),
-        s.getBlockPoolId(), s.getMostRecentCheckpointTxId(),
-        s.getCurSegmentTxId());
+    StorageInfo si = PBHelper.convert(s.getStorageInfo(), NodeType.NAME_NODE);
+    return new CheckpointSignature(si, s.getBlockPoolId(),
+        s.getMostRecentCheckpointTxId(), s.getCurSegmentTxId());
   }
 
   public static RemoteEditLogProto convert(RemoteEditLog log) {
@@ -755,9 +765,9 @@ public class PBHelper {
   }
 
   public static DatanodeRegistration convert(DatanodeRegistrationProto proto) {
+    StorageInfo si = convert(proto.getStorageInfo(), NodeType.DATA_NODE);
     return new DatanodeRegistration(PBHelper.convert(proto.getDatanodeID()),
-        PBHelper.convert(proto.getStorageInfo()), PBHelper.convert(proto
-            .getKeys()), proto.getSoftwareVersion());
+        si, PBHelper.convert(proto.getKeys()), proto.getSoftwareVersion());
   }
 
   public static DatanodeCommand convert(DatanodeCommandProto proto) {
@@ -1448,6 +1458,59 @@ public class PBHelper {
     }
   }
   
+  public static RollingUpgradeActionProto convert(RollingUpgradeAction a) {
+    switch (a) {
+    case QUERY:
+      return RollingUpgradeActionProto.QUERY;
+    case PREPARE:
+      return RollingUpgradeActionProto.START;
+    case FINALIZE:
+      return RollingUpgradeActionProto.FINALIZE;
+    default:
+      throw new IllegalArgumentException("Unexpected value: " + a);
+    }
+  }
+  
+  public static RollingUpgradeAction convert(RollingUpgradeActionProto a) {
+    switch (a) {
+    case QUERY:
+      return RollingUpgradeAction.QUERY;
+    case START:
+      return RollingUpgradeAction.PREPARE;
+    case FINALIZE:
+      return RollingUpgradeAction.FINALIZE;
+    default:
+      throw new IllegalArgumentException("Unexpected value: " + a);
+    }
+  }
+
+  public static RollingUpgradeStatusProto convertRollingUpgradeStatus(
+      RollingUpgradeStatus status) {
+    return RollingUpgradeStatusProto.newBuilder()
+        .setBlockPoolId(status.getBlockPoolId())
+        .build();
+  }
+
+  public static RollingUpgradeStatus convert(RollingUpgradeStatusProto proto) {
+    return new RollingUpgradeStatus(proto.getBlockPoolId());
+  }
+
+  public static RollingUpgradeInfoProto convert(RollingUpgradeInfo info) {
+    return RollingUpgradeInfoProto.newBuilder()
+        .setStatus(convertRollingUpgradeStatus(info))
+        .setCreatedRollbackImages(info.createdRollbackImages())
+        .setStartTime(info.getStartTime())
+        .setFinalizeTime(info.getFinalizeTime())
+        .build();
+  }
+
+  public static RollingUpgradeInfo convert(RollingUpgradeInfoProto proto) {
+    RollingUpgradeStatusProto status = proto.getStatus();
+    return new RollingUpgradeInfo(status.getBlockPoolId(),
+        proto.getCreatedRollbackImages(),
+        proto.getStartTime(), proto.getFinalizeTime());
+  }
+
   public static CorruptFileBlocks convert(CorruptFileBlocksProto c) {
     if (c == null)
       return null;
@@ -1903,6 +1966,19 @@ public class PBHelper {
     return HdfsProtos.ChecksumTypeProto.valueOf(type.id);
   }
 
+  public static DatanodeLocalInfoProto convert(DatanodeLocalInfo info) {
+    DatanodeLocalInfoProto.Builder builder = DatanodeLocalInfoProto.newBuilder();
+    builder.setSoftwareVersion(info.getSoftwareVersion());
+    builder.setConfigVersion(info.getConfigVersion());
+    builder.setUptime(info.getUptime());
+    return builder.build();
+  }
+
+  public static DatanodeLocalInfo convert(DatanodeLocalInfoProto proto) {
+    return new DatanodeLocalInfo(proto.getSoftwareVersion(),
+        proto.getConfigVersion(), proto.getUptime());
+  }
+
   public static InputStream vintPrefixed(final InputStream input)
       throws IOException {
     final int firstByte = input.read();

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/client/AsyncLogger.java

@@ -164,5 +164,7 @@ interface AsyncLogger {
 
   public ListenableFuture<Void> doRollback();
 
+  public ListenableFuture<Void> discardSegments(long startTxId);
+
   public ListenableFuture<Long> getJournalCTime();
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/client/AsyncLoggerSet.java

@@ -366,6 +366,15 @@ class AsyncLoggerSet {
     return QuorumCall.create(calls);
   }
 
+  public QuorumCall<AsyncLogger, Void> discardSegments(long startTxId) {
+    Map<AsyncLogger, ListenableFuture<Void>> calls = Maps.newHashMap();
+    for (AsyncLogger logger : loggers) {
+      ListenableFuture<Void> future = logger.discardSegments(startTxId);
+      calls.put(logger, future);
+    }
+    return QuorumCall.create(calls);
+  }
+
   public QuorumCall<AsyncLogger, Long> getJournalCTime() {
     Map<AsyncLogger, ListenableFuture<Long>> calls =
         Maps.newHashMap();

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/client/IPCLoggerChannel.java

@@ -620,7 +620,18 @@ public class IPCLoggerChannel implements AsyncLogger {
       }
     });
   }
-  
+
+  @Override
+  public ListenableFuture<Void> discardSegments(final long startTxId) {
+    return executor.submit(new Callable<Void>() {
+      @Override
+      public Void call() throws IOException {
+        getProxy().discardSegments(journalId, startTxId);
+        return null;
+      }
+    });
+  }
+
   @Override
   public ListenableFuture<Long> getJournalCTime() {
     return executor.submit(new Callable<Long>() {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/client/QuorumJournalManager.java

@@ -86,6 +86,7 @@ public class QuorumJournalManager implements JournalManager {
   private static final int FINALIZE_TIMEOUT_MS          = 60000;
   private static final int PRE_UPGRADE_TIMEOUT_MS       = 60000;
   private static final int ROLL_BACK_TIMEOUT_MS         = 60000;
+  private static final int DISCARD_SEGMENTS_TIMEOUT_MS  = 60000;
   private static final int UPGRADE_TIMEOUT_MS           = 60000;
   private static final int GET_JOURNAL_CTIME_TIMEOUT_MS = 60000;
   
@@ -600,6 +601,25 @@ public class QuorumJournalManager implements JournalManager {
     }
   }
   
+  @Override
+  public void discardSegments(long startTxId) throws IOException {
+    QuorumCall<AsyncLogger, Void> call = loggers.discardSegments(startTxId);
+    try {
+      call.waitFor(loggers.size(), loggers.size(), 0,
+          DISCARD_SEGMENTS_TIMEOUT_MS, "discardSegments");
+      if (call.countExceptions() > 0) {
+        call.rethrowException(
+            "Could not perform discardSegments of one or more JournalNodes");
+      }
+    } catch (InterruptedException e) {
+      throw new IOException(
+          "Interrupted waiting for discardSegments() response");
+    } catch (TimeoutException e) {
+      throw new IOException(
+          "Timed out waiting for discardSegments() response");
+    }
+  }
+  
   @Override
   public long getJournalCTime() throws IOException {
     QuorumCall<AsyncLogger, Long> call = loggers.getJournalCTime();

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/protocol/QJournalProtocol.java

@@ -32,6 +32,7 @@ import org.apache.hadoop.hdfs.qjournal.server.JournalNode;
 import org.apache.hadoop.hdfs.server.common.StorageInfo;
 import org.apache.hadoop.hdfs.server.namenode.JournalManager;
 import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
+import org.apache.hadoop.io.retry.Idempotent;
 import org.apache.hadoop.security.KerberosInfo;
 
 /**
@@ -156,5 +157,13 @@ public interface QJournalProtocol {
 
   public void doRollback(String journalId) throws IOException;
 
+  /**
+   * Discard journal segments whose first TxId is greater than or equal to the
+   * given txid.
+   */
+  @Idempotent
+  public void discardSegments(String journalId, long startTxId)
+      throws IOException;
+
   public Long getJournalCTime(String journalId) throws IOException;
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/protocolPB/QJournalProtocolServerSideTranslatorPB.java

@@ -30,6 +30,8 @@ import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.AcceptRec
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.AcceptRecoveryResponseProto;
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.CanRollBackRequestProto;
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.CanRollBackResponseProto;
+import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.DiscardSegmentsRequestProto;
+import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.DiscardSegmentsResponseProto;
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.DoFinalizeRequestProto;
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.DoFinalizeResponseProto;
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.DoPreUpgradeRequestProto;
@@ -64,6 +66,8 @@ import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.PurgeLogs
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.StartLogSegmentRequestProto;
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.StartLogSegmentResponseProto;
 import org.apache.hadoop.hdfs.qjournal.protocol.RequestInfo;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NodeType;
+import org.apache.hadoop.hdfs.server.common.StorageInfo;
 import org.apache.hadoop.hdfs.server.protocol.JournalProtocol;
 
 import com.google.protobuf.RpcController;
@@ -274,9 +278,9 @@ public class QJournalProtocolServerSideTranslatorPB implements QJournalProtocolP
   @Override
   public DoUpgradeResponseProto doUpgrade(RpcController controller,
       DoUpgradeRequestProto request) throws ServiceException {
+    StorageInfo si = PBHelper.convert(request.getSInfo(), NodeType.JOURNAL_NODE);
     try {
-      impl.doUpgrade(convert(request.getJid()),
-          PBHelper.convert(request.getSInfo()));
+      impl.doUpgrade(convert(request.getJid()), si);
       return DoUpgradeResponseProto.getDefaultInstance();
     } catch (IOException e) {
       throw new ServiceException(e);
@@ -298,9 +302,9 @@ public class QJournalProtocolServerSideTranslatorPB implements QJournalProtocolP
   public CanRollBackResponseProto canRollBack(RpcController controller,
       CanRollBackRequestProto request) throws ServiceException {
     try {
-      Boolean result = impl.canRollBack(convert(request.getJid()),
-          PBHelper.convert(request.getStorage()),
-          PBHelper.convert(request.getPrevStorage()),
+      StorageInfo si = PBHelper.convert(request.getStorage(), NodeType.JOURNAL_NODE);
+      Boolean result = impl.canRollBack(convert(request.getJid()), si,
+          PBHelper.convert(request.getPrevStorage(), NodeType.JOURNAL_NODE),
           request.getTargetLayoutVersion());
       return CanRollBackResponseProto.newBuilder()
           .setCanRollBack(result)
@@ -321,6 +325,18 @@ public class QJournalProtocolServerSideTranslatorPB implements QJournalProtocolP
     }
   }
 
+  @Override
+  public DiscardSegmentsResponseProto discardSegments(
+      RpcController controller, DiscardSegmentsRequestProto request)
+      throws ServiceException {
+    try {
+      impl.discardSegments(convert(request.getJid()), request.getStartTxId());
+      return DiscardSegmentsResponseProto.getDefaultInstance();
+    } catch (IOException e) {
+      throw new ServiceException(e);
+    }
+  }
+
   @Override
   public GetJournalCTimeResponseProto getJournalCTime(RpcController controller,
       GetJournalCTimeRequestProto request) throws ServiceException {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/protocolPB/QJournalProtocolTranslatorPB.java

@@ -30,6 +30,7 @@ import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos;
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.AcceptRecoveryRequestProto;
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.CanRollBackRequestProto;
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.CanRollBackResponseProto;
+import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.DiscardSegmentsRequestProto;
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.DoFinalizeRequestProto;
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.DoPreUpgradeRequestProto;
 import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.DoRollbackRequestProto;
@@ -354,6 +355,19 @@ public class QJournalProtocolTranslatorPB implements ProtocolMetaInterface,
     }
   }
 
+  @Override
+  public void discardSegments(String journalId, long startTxId)
+      throws IOException {
+    try {
+      rpcProxy.discardSegments(NULL_CONTROLLER,
+          DiscardSegmentsRequestProto.newBuilder()
+            .setJid(convertJournalId(journalId)).setStartTxId(startTxId)
+            .build());
+    } catch (ServiceException e) {
+      throw ProtobufHelper.getRemoteException(e);
+    }
+  }
+
   @Override
   public Long getJournalCTime(String journalId) throws IOException {
     try {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/server/Journal.java

@@ -1037,6 +1037,12 @@ public class Journal implements Closeable {
     storage.getJournalManager().doRollback();
   }
 
+  synchronized void discardSegments(long startTxId) throws IOException {
+    storage.getJournalManager().discardSegments(startTxId);
+    // we delete all the segments after the startTxId. let's reset committedTxnId 
+    committedTxnId.set(startTxId - 1);
+  }
+
   public Long getJournalCTime() throws IOException {
     return storage.getJournalManager().getJournalCTime();
   }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/server/JournalNode.java

@@ -309,6 +309,11 @@ public class JournalNode implements Tool, Configurable, JournalNodeMXBean {
     getOrCreateJournal(journalId).doRollback();
   }
 
+  public void discardSegments(String journalId, long startTxId)
+      throws IOException {
+    getOrCreateJournal(journalId).discardSegments(startTxId);
+  }
+
   public Long getJournalCTime(String journalId) throws IOException {
     return getOrCreateJournal(journalId).getJournalCTime();
   }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/qjournal/server/JournalNodeRpcServer.java

@@ -233,6 +233,12 @@ class JournalNodeRpcServer implements QJournalProtocol {
     jn.doRollback(journalId);
   }
 
+  @Override
+  public void discardSegments(String journalId, long startTxId)
+      throws IOException {
+    jn.discardSegments(journalId, startTxId);
+  }
+
   @Override
   public Long getJournalCTime(String journalId) throws IOException {
     return jn.getJournalCTime(journalId);

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java

@@ -234,6 +234,22 @@ public class BlockManager {
    */
   private boolean shouldPostponeBlocksFromFuture = false;
 
+  /**
+   * Process replication queues asynchronously to allow namenode safemode exit
+   * and failover to be faster. HDFS-5496
+   */
+  private Daemon replicationQueuesInitializer = null;
+  /**
+   * Number of blocks to process asychronously for replication queues
+   * initialization once aquired the namesystem lock. Remaining blocks will be
+   * processed again after aquiring lock again.
+   */
+  private int numBlocksPerIteration;
+  /**
+   * Progress of the Replication queues initialisation.
+   */
+  private double replicationQueuesInitProgress = 0.0;
+
   /** for block replicas placement */
   private BlockPlacementPolicy blockplacement;
 
@@ -310,6 +326,9 @@ public class BlockManager {
     this.maxNumBlocksToLog =
         conf.getLong(DFSConfigKeys.DFS_MAX_NUM_BLOCKS_TO_LOG_KEY,
             DFSConfigKeys.DFS_MAX_NUM_BLOCKS_TO_LOG_DEFAULT);
+    this.numBlocksPerIteration = conf.getInt(
+        DFSConfigKeys.DFS_BLOCK_MISREPLICATION_PROCESSING_LIMIT,
+        DFSConfigKeys.DFS_BLOCK_MISREPLICATION_PROCESSING_LIMIT_DEFAULT);
     
     LOG.info("defaultReplication         = " + defaultReplication);
     LOG.info("maxReplication             = " + maxReplication);
@@ -2361,45 +2380,127 @@ assert storedBlock.findDatanode(dn) < 0 : "Block " + block
    */
   public void processMisReplicatedBlocks() {
     assert namesystem.hasWriteLock();
-
-    long nrInvalid = 0, nrOverReplicated = 0, nrUnderReplicated = 0, nrPostponed = 0,
-         nrUnderConstruction = 0;
+    stopReplicationInitializer();
     neededReplications.clear();
-    for (BlockInfo block : blocksMap.getBlocks()) {
-      MisReplicationResult res = processMisReplicatedBlock(block);
-      if (LOG.isTraceEnabled()) {
-        LOG.trace("block " + block + ": " + res);
-      }
-      switch (res) {
-      case UNDER_REPLICATED:
-        nrUnderReplicated++;
-        break;
-      case OVER_REPLICATED:
-        nrOverReplicated++;
-        break;
-      case INVALID:
-        nrInvalid++;
-        break;
-      case POSTPONE:
-        nrPostponed++;
-        postponeBlock(block);
-        break;
-      case UNDER_CONSTRUCTION:
-        nrUnderConstruction++;
-        break;
-      case OK:
-        break;
-      default:
-        throw new AssertionError("Invalid enum value: " + res);
+    replicationQueuesInitializer = new Daemon() {
+
+      @Override
+      public void run() {
+        try {
+          processMisReplicatesAsync();
+        } catch (InterruptedException ie) {
+          LOG.info("Interrupted while processing replication queues.");
+        } catch (Exception e) {
+          LOG.error("Error while processing replication queues async", e);
+        }
+      }
+    };
+    replicationQueuesInitializer.setName("Replication Queue Initializer");
+    replicationQueuesInitializer.start();
+  }
+
+  /*
+   * Stop the ongoing initialisation of replication queues
+   */
+  private void stopReplicationInitializer() {
+    if (replicationQueuesInitializer != null) {
+      replicationQueuesInitializer.interrupt();
+      try {
+        replicationQueuesInitializer.join();
+      } catch (final InterruptedException e) {
+        LOG.warn("Interrupted while waiting for replicationQueueInitializer. Returning..");
+        return;
+      } finally {
+        replicationQueuesInitializer = null;
       }
     }
-    
-    LOG.info("Total number of blocks            = " + blocksMap.size());
-    LOG.info("Number of invalid blocks          = " + nrInvalid);
-    LOG.info("Number of under-replicated blocks = " + nrUnderReplicated);
-    LOG.info("Number of  over-replicated blocks = " + nrOverReplicated +
-        ((nrPostponed > 0) ? ( " (" + nrPostponed + " postponed)") : ""));
-    LOG.info("Number of blocks being written    = " + nrUnderConstruction);
+  }
+
+  /*
+   * Since the BlocksMapGset does not throw the ConcurrentModificationException
+   * and supports further iteration after modification to list, there is a
+   * chance of missing the newly added block while iterating. Since every
+   * addition to blocksMap will check for mis-replication, missing mis-replication
+   * check for new blocks will not be a problem.
+   */
+  private void processMisReplicatesAsync() throws InterruptedException {
+    long nrInvalid = 0, nrOverReplicated = 0;
+    long nrUnderReplicated = 0, nrPostponed = 0, nrUnderConstruction = 0;
+    long startTimeMisReplicatedScan = Time.now();
+    Iterator<BlockInfo> blocksItr = blocksMap.getBlocks().iterator();
+    long totalBlocks = blocksMap.size();
+    replicationQueuesInitProgress = 0;
+    long totalProcessed = 0;
+    while (namesystem.isRunning() && !Thread.currentThread().isInterrupted()) {
+      int processed = 0;
+      namesystem.writeLockInterruptibly();
+      try {
+        while (processed < numBlocksPerIteration && blocksItr.hasNext()) {
+          BlockInfo block = blocksItr.next();
+          MisReplicationResult res = processMisReplicatedBlock(block);
+          if (LOG.isTraceEnabled()) {
+            LOG.trace("block " + block + ": " + res);
+          }
+          switch (res) {
+          case UNDER_REPLICATED:
+            nrUnderReplicated++;
+            break;
+          case OVER_REPLICATED:
+            nrOverReplicated++;
+            break;
+          case INVALID:
+            nrInvalid++;
+            break;
+          case POSTPONE:
+            nrPostponed++;
+            postponeBlock(block);
+            break;
+          case UNDER_CONSTRUCTION:
+            nrUnderConstruction++;
+            break;
+          case OK:
+            break;
+          default:
+            throw new AssertionError("Invalid enum value: " + res);
+          }
+          processed++;
+        }
+        totalProcessed += processed;
+        // there is a possibility that if any of the blocks deleted/added during
+        // initialisation, then progress might be different.
+        replicationQueuesInitProgress = Math.min((double) totalProcessed
+            / totalBlocks, 1.0);
+
+        if (!blocksItr.hasNext()) {
+          LOG.info("Total number of blocks            = " + blocksMap.size());
+          LOG.info("Number of invalid blocks          = " + nrInvalid);
+          LOG.info("Number of under-replicated blocks = " + nrUnderReplicated);
+          LOG.info("Number of  over-replicated blocks = " + nrOverReplicated
+              + ((nrPostponed > 0) ? (" (" + nrPostponed + " postponed)") : ""));
+          LOG.info("Number of blocks being written    = " + nrUnderConstruction);
+          NameNode.stateChangeLog
+              .info("STATE* Replication Queue initialization "
+                  + "scan for invalid, over- and under-replicated blocks "
+                  + "completed in " + (Time.now() - startTimeMisReplicatedScan)
+                  + " msec");
+          break;
+        }
+      } finally {
+        namesystem.writeUnlock();
+      }
+    }
+    if (Thread.currentThread().isInterrupted()) {
+      LOG.info("Interrupted while processing replication queues.");
+    }
+  }
+
+  /**
+   * Get the progress of the Replication queues initialisation
+   * 
+   * @return Returns values between 0 and 1 for the progress.
+   */
+  public double getReplicationQueuesInitProgress() {
+    return replicationQueuesInitProgress;
   }
 
   /**
@@ -3365,6 +3466,7 @@ assert storedBlock.findDatanode(dn) < 0 : "Block " + block
   }
 
   public void shutdown() {
+    stopReplicationInitializer();
     blocksMap.close();
   }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlocksMap.java

@@ -23,6 +23,7 @@ import org.apache.hadoop.hdfs.protocol.Block;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeStorage;
 import org.apache.hadoop.util.GSet;
 import org.apache.hadoop.util.LightWeightGSet;
+import org.apache.hadoop.util.LightWeightGSet.SetIterator;
 
 import com.google.common.base.Predicate;
 import com.google.common.collect.Iterables;
@@ -66,7 +67,20 @@ class BlocksMap {
   BlocksMap(int capacity) {
     // Use 2% of total memory to size the GSet capacity
     this.capacity = capacity;
-    this.blocks = new LightWeightGSet<Block, BlockInfo>(capacity);
+    this.blocks = new LightWeightGSet<Block, BlockInfo>(capacity) {
+      @Override
+      public Iterator<BlockInfo> iterator() {
+        SetIterator iterator = new SetIterator();
+        /*
+         * Not tracking any modifications to set. As this set will be used
+         * always under FSNameSystem lock, modifications will not cause any
+         * ConcurrentModificationExceptions. But there is a chance of missing
+         * newly added elements during iteration.
+         */
+        iterator.setTrackModification(false);
+        return iterator;
+      }
+    };
   }
 
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/HdfsServerConstants.java

@@ -20,10 +20,14 @@ package org.apache.hadoop.hdfs.server.common;
 import java.io.DataInput;
 import java.io.DataOutput;
 import java.io.IOException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.hdfs.server.namenode.MetaRecoveryContext;
 
+import com.google.common.base.Preconditions;
+
 /************************************
  * Some handy internal HDFS constants
  *
@@ -43,6 +47,33 @@ public final class HdfsServerConstants {
     JOURNAL_NODE;
   }
 
+  /** Startup options for rolling upgrade. */
+  public static enum RollingUpgradeStartupOption{
+    ROLLBACK, DOWNGRADE, STARTED;
+
+    public String getOptionString() {
+      return StartupOption.ROLLINGUPGRADE.getName() + " "
+          + name().toLowerCase();
+    }
+
+    public boolean matches(StartupOption option) {
+      return option == StartupOption.ROLLINGUPGRADE
+          && option.getRollingUpgradeStartupOption() == this;
+    }
+
+    private static final RollingUpgradeStartupOption[] VALUES = values();
+
+    static RollingUpgradeStartupOption fromString(String s) {
+      for(RollingUpgradeStartupOption opt : VALUES) {
+        if (opt.name().equalsIgnoreCase(s)) {
+          return opt;
+        }
+      }
+      throw new IllegalArgumentException("Failed to convert \"" + s
+          + "\" to " + RollingUpgradeStartupOption.class.getSimpleName());
+    }
+  }
+
   /** Startup options */
   static public enum StartupOption{
     FORMAT  ("-format"),
@@ -54,6 +85,7 @@ public final class HdfsServerConstants {
     UPGRADE ("-upgrade"),
     ROLLBACK("-rollback"),
     FINALIZE("-finalize"),
+    ROLLINGUPGRADE("-rollingUpgrade"),
     IMPORT  ("-importCheckpoint"),
     BOOTSTRAPSTANDBY("-bootstrapStandby"),
     INITIALIZESHAREDEDITS("-initializeSharedEdits"),
@@ -61,12 +93,18 @@ public final class HdfsServerConstants {
     FORCE("-force"),
     NONINTERACTIVE("-nonInteractive"),
     RENAMERESERVED("-renameReserved");
-    
+
+    private static final Pattern ENUM_WITH_ROLLING_UPGRADE_OPTION = Pattern.compile(
+        "(\\w+)\\((\\w+)\\)");
+
     private final String name;
     
     // Used only with format and upgrade options
     private String clusterId = null;
     
+    // Used only by rolling upgrade
+    private RollingUpgradeStartupOption rollingUpgradeStartupOption;
+
     // Used only with format option
     private boolean isForceFormat = false;
     private boolean isInteractiveFormat = true;
@@ -94,6 +132,16 @@ public final class HdfsServerConstants {
     public String getClusterId() {
       return clusterId;
     }
+    
+    public void setRollingUpgradeStartupOption(String opt) {
+      Preconditions.checkState(this == ROLLINGUPGRADE);
+      rollingUpgradeStartupOption = RollingUpgradeStartupOption.fromString(opt);
+    }
+    
+    public RollingUpgradeStartupOption getRollingUpgradeStartupOption() {
+      Preconditions.checkState(this == ROLLINGUPGRADE);
+      return rollingUpgradeStartupOption;
+    }
 
     public MetaRecoveryContext createRecoveryContext() {
       if (!name.equals(RECOVER.name))
@@ -124,6 +172,27 @@ public final class HdfsServerConstants {
     public void setInteractiveFormat(boolean interactive) {
       isInteractiveFormat = interactive;
     }
+    
+    @Override
+    public String toString() {
+      if (this == ROLLINGUPGRADE) {
+        return new StringBuilder(super.toString())
+            .append("(").append(getRollingUpgradeStartupOption()).append(")")
+            .toString();
+      }
+      return super.toString();
+    }
+
+    static public StartupOption getEnum(String value) {
+      Matcher matcher = ENUM_WITH_ROLLING_UPGRADE_OPTION.matcher(value);
+      if (matcher.matches()) {
+        StartupOption option = StartupOption.valueOf(matcher.group(1));
+        option.setRollingUpgradeStartupOption(matcher.group(2));
+        return option;
+      } else {
+        return StartupOption.valueOf(value);
+      }
+    }
   }
 
   // Timeouts for communicating with DataNode for streaming writes/reads

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/IncorrectVersionException.java

@@ -45,8 +45,9 @@ public class IncorrectVersionException extends IOException {
         minimumVersion + "'");
   }
   
-  public IncorrectVersionException(int versionReported, String ofWhat) {
-    this(versionReported, ofWhat, HdfsConstants.LAYOUT_VERSION);
+  public IncorrectVersionException(int currentLayoutVersion,
+      int versionReported, String ofWhat) {
+    this(versionReported, ofWhat, currentLayoutVersion);
   }
   
   public IncorrectVersionException(int versionReported,

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/Storage.java

@@ -34,7 +34,6 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.fs.Path;
-import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NodeType;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
 import org.apache.hadoop.util.ToolRunner;
@@ -116,7 +115,6 @@ public abstract class Storage extends StorageInfo {
     public boolean isOfType(StorageDirType type);
   }
   
-  protected NodeType storageType;    // Type of the node using this storage 
   protected List<StorageDirectory> storageDirs = new ArrayList<StorageDirectory>();
   
   private class DirIterator implements Iterator<StorageDirectory> {
@@ -781,13 +779,11 @@ public abstract class Storage extends StorageInfo {
    * Create empty storage info of the specified type
    */
   protected Storage(NodeType type) {
-    super();
-    this.storageType = type;
+    super(type);
   }
   
-  protected Storage(NodeType type, StorageInfo storageInfo) {
+  protected Storage(StorageInfo storageInfo) {
     super(storageInfo);
-    this.storageType = type;
   }
   
   public int getNumStorageDirs() {
@@ -931,35 +927,11 @@ public abstract class Storage extends StorageInfo {
     props.setProperty("storageType", storageType.toString());
     props.setProperty("namespaceID", String.valueOf(namespaceID));
     // Set clusterID in version with federation support
-    if (versionSupportsFederation()) {
+    if (versionSupportsFederation(getServiceLayoutFeatureMap())) {
       props.setProperty("clusterID", clusterID);
     }
     props.setProperty("cTime", String.valueOf(cTime));
   }
-  
-  /**
-   * Get common storage fields.
-   * Should be overloaded if additional fields need to be get.
-   * 
-   * @param props
-   * @throws IOException
-   */
-  protected void setFieldsFromProperties(
-      Properties props, StorageDirectory sd) throws IOException {
-    super.setFieldsFromProperties(props, sd);
-    setStorageType(props, sd);
-  }
-  
-  /** Validate and set storage type from {@link Properties}*/
-  protected void setStorageType(Properties props, StorageDirectory sd)
-      throws InconsistentFSStateException {
-    NodeType type = NodeType.valueOf(getProperty(props, sd, "storageType"));
-    if (!storageType.equals(type)) {
-      throw new InconsistentFSStateException(sd.root,
-          "node type is incompatible with others.");
-    }
-    storageType = type;
-  }
 
   /**
    * Write properties to the VERSION file in the given storage directory.
@@ -1025,7 +997,7 @@ public abstract class Storage extends StorageInfo {
    * @throws IOException
    */
   public void writeAll() throws IOException {
-    this.layoutVersion = HdfsConstants.LAYOUT_VERSION;
+    this.layoutVersion = getServiceLayoutVersion();
     for (Iterator<StorageDirectory> it = storageDirs.iterator(); it.hasNext();) {
       writeProperties(it.next());
     }
@@ -1048,7 +1020,6 @@ public abstract class Storage extends StorageInfo {
   public static String getRegistrationID(StorageInfo storage) {
     return "NS-" + Integer.toString(storage.getNamespaceID())
       + "-" + storage.getClusterID()
-      + "-" + Integer.toString(storage.getLayoutVersion())
       + "-" + Long.toString(storage.getCTime());
   }
   

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/StorageInfo.java

@@ -21,13 +21,19 @@ import java.io.File;
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.RandomAccessFile;
+import java.util.Map;
 import java.util.Properties;
+import java.util.SortedSet;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
+import org.apache.hadoop.hdfs.protocol.LayoutVersion.LayoutFeature;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NodeType;
 import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
+import org.apache.hadoop.hdfs.server.datanode.DataNodeLayoutVersion;
+import org.apache.hadoop.hdfs.server.namenode.NameNodeLayoutVersion;
 
 import com.google.common.base.Joiner;
 
@@ -42,22 +48,26 @@ public class StorageInfo {
   public int   namespaceID;     // id of the file system
   public String clusterID;      // id of the cluster
   public long  cTime;           // creation time of the file system state
+
+  protected final NodeType storageType; // Type of the node using this storage 
   
   protected static final String STORAGE_FILE_VERSION    = "VERSION";
- 
-  public StorageInfo () {
-    this(0, 0, "", 0L);
+
+  public StorageInfo(NodeType type) {
+    this(0, 0, "", 0L, type);
   }
 
-  public StorageInfo(int layoutV, int nsID, String cid, long cT) {
+  public StorageInfo(int layoutV, int nsID, String cid, long cT, NodeType type) {
     layoutVersion = layoutV;
     clusterID = cid;
     namespaceID = nsID;
     cTime = cT;
+    storageType = type;
   }
   
   public StorageInfo(StorageInfo from) {
-    setStorageInfo(from);
+    this(from.layoutVersion, from.namespaceID, from.clusterID, from.cTime,
+        from.storageType);
   }
 
   /**
@@ -90,8 +100,10 @@ public class StorageInfo {
     cTime = from.cTime;
   }
 
-  public boolean versionSupportsFederation() {
-    return LayoutVersion.supports(Feature.FEDERATION, layoutVersion);
+  public boolean versionSupportsFederation(
+      Map<Integer, SortedSet<LayoutFeature>> map) {
+    return LayoutVersion.supports(map, LayoutVersion.Feature.FEDERATION,
+        layoutVersion);
   }
   
   @Override
@@ -145,6 +157,21 @@ public class StorageInfo {
     setNamespaceID(props, sd);
     setcTime(props, sd);
     setClusterId(props, layoutVersion, sd);
+    checkStorageType(props, sd);
+  }
+  
+  /** Validate and set storage type from {@link Properties}*/
+  protected void checkStorageType(Properties props, StorageDirectory sd)
+      throws InconsistentFSStateException {
+    if (storageType == null) { //don't care about storage type
+      return;
+    }
+    NodeType type = NodeType.valueOf(getProperty(props, sd, "storageType"));
+    if (!storageType.equals(type)) {
+      throw new InconsistentFSStateException(sd.root,
+          "Incompatible node types: storageType=" + storageType
+          + " but StorageDirectory type=" + type);
+    }
   }
   
   /** Validate and set ctime from {@link Properties}*/
@@ -157,7 +184,8 @@ public class StorageInfo {
   protected void setClusterId(Properties props, int layoutVersion,
       StorageDirectory sd) throws InconsistentFSStateException {
     // Set cluster ID in version that supports federation
-    if (LayoutVersion.supports(Feature.FEDERATION, layoutVersion)) {
+    if (LayoutVersion.supports(getServiceLayoutFeatureMap(),
+        Feature.FEDERATION, layoutVersion)) {
       String cid = getProperty(props, sd, "clusterID");
       if (!(clusterID.equals("") || cid.equals("") || clusterID.equals(cid))) {
         throw new InconsistentFSStateException(sd.getRoot(),
@@ -171,9 +199,9 @@ public class StorageInfo {
   protected void setLayoutVersion(Properties props, StorageDirectory sd)
       throws IncorrectVersionException, InconsistentFSStateException {
     int lv = Integer.parseInt(getProperty(props, sd, "layoutVersion"));
-    if (lv < HdfsConstants.LAYOUT_VERSION) { // future version
-      throw new IncorrectVersionException(lv, "storage directory "
-          + sd.root.getAbsolutePath());
+    if (lv < getServiceLayoutVersion()) { // future version
+      throw new IncorrectVersionException(getServiceLayoutVersion(), lv,
+          "storage directory " + sd.root.getAbsolutePath());
     }
     layoutVersion = lv;
   }
@@ -189,6 +217,16 @@ public class StorageInfo {
     namespaceID = nsId;
   }
   
+  public int getServiceLayoutVersion() {
+    return storageType == NodeType.DATA_NODE ? HdfsConstants.DATANODE_LAYOUT_VERSION
+        : HdfsConstants.NAMENODE_LAYOUT_VERSION;
+  }
+
+  public Map<Integer, SortedSet<LayoutFeature>> getServiceLayoutFeatureMap() {
+    return storageType == NodeType.DATA_NODE? DataNodeLayoutVersion.FEATURES
+        : NameNodeLayoutVersion.FEATURES;
+  }
+  
   static String getProperty(Properties props, StorageDirectory sd,
       String name) throws InconsistentFSStateException {
     String property = props.getProperty(name);
@@ -198,7 +236,7 @@ public class StorageInfo {
     }
     return property;
   }
-  
+
   public static Properties readPropertiesFile(File from) throws IOException {
     RandomAccessFile file = new RandomAccessFile(from, "rws");
     FileInputStream in = null;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPOfferService.java

@@ -17,13 +17,10 @@
  */
 package org.apache.hadoop.hdfs.server.datanode;
 
-import java.io.IOException;
-import java.net.InetSocketAddress;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Set;
-import java.util.concurrent.CopyOnWriteArrayList;
-
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
+import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
 import org.apache.commons.logging.Log;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.ha.HAServiceProtocol.HAServiceState;
@@ -32,24 +29,15 @@ import org.apache.hadoop.hdfs.protocol.Block;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolClientSideTranslatorPB;
-import org.apache.hadoop.hdfs.server.protocol.BalancerBandwidthCommand;
-import org.apache.hadoop.hdfs.server.protocol.BlockCommand;
-import org.apache.hadoop.hdfs.server.protocol.BlockIdCommand;
-import org.apache.hadoop.hdfs.server.protocol.BlockRecoveryCommand;
-import org.apache.hadoop.hdfs.server.protocol.DatanodeCommand;
-import org.apache.hadoop.hdfs.server.protocol.DatanodeProtocol;
-import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
-import org.apache.hadoop.hdfs.server.protocol.FinalizeCommand;
-import org.apache.hadoop.hdfs.server.protocol.KeyUpdateCommand;
-import org.apache.hadoop.hdfs.server.protocol.NNHAStatusHeartbeat;
-import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
-import org.apache.hadoop.hdfs.server.protocol.ReceivedDeletedBlockInfo;
+import org.apache.hadoop.hdfs.server.protocol.*;
 import org.apache.hadoop.hdfs.server.protocol.ReceivedDeletedBlockInfo.BlockStatus;
 
-import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Preconditions;
-import com.google.common.collect.Lists;
-import com.google.common.collect.Sets;
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 /**
  * One instance per block-pool/namespace on the DN, which handles the
@@ -413,6 +401,18 @@ class BPOfferService {
     return Lists.newArrayList(bpServices);
   }
   
+  /**
+   * Signal the current rolling upgrade status as indicated by the NN.
+   * @param inProgress true if a rolling upgrade is in progress
+   */
+  void signalRollingUpgrade(boolean inProgress) {
+    if (inProgress) {
+      dn.getFSDataset().enableTrash(getBlockPoolId());
+    } else {
+      dn.getFSDataset().restoreTrash(getBlockPoolId());
+    }
+  }
+
   /**
    * Update the BPOS's view of which NN is active, based on a heartbeat
    * response from one of the actors.
@@ -611,7 +611,8 @@ class BPOfferService {
       // See HDFS-2987.
       throw new UnsupportedOperationException("Received unimplemented DNA_SHUTDOWN");
     case DatanodeProtocol.DNA_FINALIZE:
-      String bp = ((FinalizeCommand) cmd).getBlockPoolId(); 
+      String bp = ((FinalizeCommand) cmd).getBlockPoolId();
+      LOG.info("Got finalize command for block pool " + bp);
       assert getBlockPoolId().equals(bp) :
         "BP " + getBlockPoolId() + " received DNA_FINALIZE " +
         "for other block pool " + bp;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPServiceActor.java

@@ -33,8 +33,8 @@ import org.apache.hadoop.hdfs.StorageType;
 import org.apache.hadoop.hdfs.protocol.BlockListAsLongs;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
-import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeStatus;
 import org.apache.hadoop.hdfs.protocol.UnregisteredNodeException;
 import org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolClientSideTranslatorPB;
 import org.apache.hadoop.hdfs.server.common.IncorrectVersionException;
@@ -204,14 +204,6 @@ class BPServiceActor implements Runnable {
           "DataNode version '" + dnVersion + "' but is within acceptable " +
           "limits. Note: This is normal during a rolling upgrade.");
     }
-
-    if (HdfsConstants.LAYOUT_VERSION != nsInfo.getLayoutVersion()) {
-      LOG.warn("DataNode and NameNode layout versions must be the same." +
-        " Expected: "+ HdfsConstants.LAYOUT_VERSION +
-        " actual "+ nsInfo.getLayoutVersion());
-      throw new IncorrectVersionException(
-          nsInfo.getLayoutVersion(), "namenode");
-    }
   }
 
   private void connectToNNAndHandshake() throws IOException {
@@ -625,6 +617,20 @@ class BPServiceActor implements Runnable {
     bpos.shutdownActor(this);
   }
 
+  private void handleRollingUpgradeStatus(HeartbeatResponse resp) {
+    RollingUpgradeStatus rollingUpgradeStatus = resp.getRollingUpdateStatus();
+    if (rollingUpgradeStatus != null &&
+        rollingUpgradeStatus.getBlockPoolId().compareTo(bpos.getBlockPoolId()) != 0) {
+      // Can this ever occur?
+      LOG.error("Invalid BlockPoolId " +
+          rollingUpgradeStatus.getBlockPoolId() +
+          " in HeartbeatResponse. Expected " +
+          bpos.getBlockPoolId());
+    } else {
+      bpos.signalRollingUpgrade(rollingUpgradeStatus != null);
+    }
+  }
+
   /**
    * Main loop for each BP thread. Run until shutdown,
    * forever calling remote NameNode functions.
@@ -671,6 +677,10 @@ class BPServiceActor implements Runnable {
                 this, resp.getNameNodeHaState());
             state = resp.getNameNodeHaState().getState();
 
+            if (state == HAServiceState.ACTIVE) {
+              handleRollingUpgradeStatus(resp);
+            }
+
             long startProcessCommands = now();
             if (!processCommand(resp.getCommands()))
               continue;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockPoolSliceStorage.java

@@ -18,29 +18,29 @@
 
 package org.apache.hadoop.hdfs.server.datanode;
 
-import java.io.File;
-import java.io.IOException;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Iterator;
-import java.util.Properties;
-import java.util.regex.Matcher;
-import java.util.regex.Pattern;
-
+import com.google.common.annotations.VisibleForTesting;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.fs.HardLink;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
-import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NodeType;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
 import org.apache.hadoop.hdfs.server.common.InconsistentFSStateException;
 import org.apache.hadoop.hdfs.server.common.Storage;
 import org.apache.hadoop.hdfs.server.common.StorageInfo;
-import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NodeType;
-import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
 import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
 import org.apache.hadoop.util.Daemon;
 
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.Properties;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
 /**
  * Manages storage for the set of BlockPoolSlices which share a particular 
  * block pool id, on this DataNode.
@@ -58,14 +58,24 @@ import org.apache.hadoop.util.Daemon;
  */
 @InterfaceAudience.Private
 public class BlockPoolSliceStorage extends Storage {
-  private static final Pattern BLOCK_POOL_PATH_PATTERN = Pattern
-      .compile("^(.*)"
-          + "(\\/BP-[0-9]+\\-\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\-[0-9]+\\/.*)$");
+  static final String TRASH_ROOT_DIR = "trash";
+
+  private static final String BLOCK_POOL_ID_PATTERN_BASE =
+      "/BP-\\d+-\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}-\\d+/";
+
+  private static final Pattern BLOCK_POOL_PATH_PATTERN = Pattern.compile(
+      "^(.*)(" + BLOCK_POOL_ID_PATTERN_BASE + ")(.*)$");
+
+  private static final Pattern BLOCK_POOL_CURRENT_PATH_PATTERN = Pattern.compile(
+      "^(.*)(" + BLOCK_POOL_ID_PATTERN_BASE + ")(" + STORAGE_DIR_CURRENT + ")(.*)$");
+
+  private static final Pattern BLOCK_POOL_TRASH_PATH_PATTERN = Pattern.compile(
+      "^(.*)(" + BLOCK_POOL_ID_PATTERN_BASE + ")(" + TRASH_ROOT_DIR + ")(.*)$");
 
   private String blockpoolID = ""; // id of the blockpool
 
   public BlockPoolSliceStorage(StorageInfo storageInfo, String bpid) {
-    super(NodeType.DATA_NODE, storageInfo);
+    super(storageInfo);
     blockpoolID = bpid;
   }
 
@@ -93,9 +103,7 @@ public class BlockPoolSliceStorage extends Storage {
    */
   void recoverTransitionRead(DataNode datanode, NamespaceInfo nsInfo,
       Collection<File> dataDirs, StartupOption startOpt) throws IOException {
-    assert HdfsConstants.LAYOUT_VERSION == nsInfo.getLayoutVersion() 
-        : "Block-pool and name-node layout versions must be the same.";
-
+    LOG.info("Analyzing storage directories for bpid " + nsInfo.getBlockPoolID());
     // 1. For each BP data directory analyze the state and
     // check whether all is consistent before transitioning.
     this.storageDirs = new ArrayList<StorageDirectory>(dataDirs.size());
@@ -143,8 +151,6 @@ public class BlockPoolSliceStorage extends Storage {
     // while others could be up-to-date for the regular startup.
     for (int idx = 0; idx < getNumStorageDirs(); idx++) {
       doTransition(getStorageDir(idx), nsInfo, startOpt);
-      assert getLayoutVersion() == nsInfo.getLayoutVersion() 
-          : "Data-node and name-node layout versions must be the same.";
       assert getCTime() == nsInfo.getCTime() 
           : "Data-node and name-node CTimes must be the same.";
     }
@@ -167,7 +173,7 @@ public class BlockPoolSliceStorage extends Storage {
 
   /**
    * Format a block pool slice storage. 
-   * @param sd the block pool storage
+   * @param bpSdir the block pool storage
    * @param nsInfo the name space info
    * @throws IOException Signals that an I/O exception has occurred.
    */
@@ -175,11 +181,10 @@ public class BlockPoolSliceStorage extends Storage {
     LOG.info("Formatting block pool " + blockpoolID + " directory "
         + bpSdir.getCurrentDir());
     bpSdir.clearDirectory(); // create directory
-    this.layoutVersion = HdfsConstants.LAYOUT_VERSION;
+    this.layoutVersion = HdfsConstants.DATANODE_LAYOUT_VERSION;
     this.cTime = nsInfo.getCTime();
     this.namespaceID = nsInfo.getNamespaceID();
     this.blockpoolID = nsInfo.getBlockPoolID();
-    this.storageType = NodeType.DATA_NODE;
     writeProperties(bpSdir);
   }
 
@@ -206,7 +211,7 @@ public class BlockPoolSliceStorage extends Storage {
     
     if (!blockpoolID.equals("") && !blockpoolID.equals(bpid)) {
       throw new InconsistentFSStateException(storage,
-          "Unexepcted blockpoolID " + bpid + " . Expected " + blockpoolID);
+          "Unexpected blockpoolID " + bpid + ". Expected " + blockpoolID);
     }
     blockpoolID = bpid;
   }
@@ -230,7 +235,6 @@ public class BlockPoolSliceStorage extends Storage {
    * Upgrade if this.LV > LAYOUT_VERSION || this.cTime < namenode.cTime Regular
    * startup if this.LV = LAYOUT_VERSION && this.cTime = namenode.cTime
    * 
-   * @param dn DataNode to which this storage belongs to
    * @param sd storage directory <SD>/current/<bpid>
    * @param nsInfo namespace info
    * @param startOpt startup option
@@ -238,12 +242,18 @@ public class BlockPoolSliceStorage extends Storage {
    */
   private void doTransition(StorageDirectory sd,
       NamespaceInfo nsInfo, StartupOption startOpt) throws IOException {
-    if (startOpt == StartupOption.ROLLBACK)
+    if (startOpt == StartupOption.ROLLBACK) {
       doRollback(sd, nsInfo); // rollback if applicable
-    
+    } else {
+      // Restore all the files in the trash. The restored files are retained
+      // during rolling upgrade rollback. They are deleted during rolling
+      // upgrade downgrade.
+      int restored = restoreBlockFilesFromTrash(getTrashRootDir(sd));
+      LOG.info("Restored " + restored + " block files from trash.");
+    }
     readProperties(sd);
     checkVersionUpgradable(this.layoutVersion);
-    assert this.layoutVersion >= HdfsConstants.LAYOUT_VERSION 
+    assert this.layoutVersion >= HdfsConstants.DATANODE_LAYOUT_VERSION 
        : "Future version is not allowed";
     if (getNamespaceID() != nsInfo.getNamespaceID()) {
       throw new IOException("Incompatible namespaceIDs in "
@@ -257,11 +267,11 @@ public class BlockPoolSliceStorage extends Storage {
           + nsInfo.getBlockPoolID() + "; datanode blockpoolID = "
           + blockpoolID);
     }
-    if (this.layoutVersion == HdfsConstants.LAYOUT_VERSION
+    if (this.layoutVersion == HdfsConstants.DATANODE_LAYOUT_VERSION
         && this.cTime == nsInfo.getCTime()) {
       return; // regular startup
     }
-    if (this.layoutVersion > HdfsConstants.LAYOUT_VERSION
+    if (this.layoutVersion > HdfsConstants.DATANODE_LAYOUT_VERSION
         || this.cTime < nsInfo.getCTime()) {
       doUpgrade(sd, nsInfo); // upgrade
       return;
@@ -294,7 +304,8 @@ public class BlockPoolSliceStorage extends Storage {
    */
   void doUpgrade(StorageDirectory bpSd, NamespaceInfo nsInfo) throws IOException {
     // Upgrading is applicable only to release with federation or after
-    if (!LayoutVersion.supports(Feature.FEDERATION, layoutVersion)) {
+    if (!DataNodeLayoutVersion.supports(
+        LayoutVersion.Feature.FEDERATION, layoutVersion)) {
       return;
     }
     LOG.info("Upgrading block pool storage directory " + bpSd.getRoot()
@@ -322,18 +333,20 @@ public class BlockPoolSliceStorage extends Storage {
     File bpTmpDir = bpSd.getPreviousTmp();
     assert !bpTmpDir.exists() : "previous.tmp directory must not exist.";
     
-    // 2. Rename <SD>/curernt/<bpid>/current to <SD>/curernt/<bpid>/previous.tmp
+    // 2. Rename <SD>/current/<bpid>/current to
+    //    <SD>/current/<bpid>/previous.tmp
     rename(bpCurDir, bpTmpDir);
     
     // 3. Create new <SD>/current with block files hardlinks and VERSION
     linkAllBlocks(bpTmpDir, bpCurDir);
-    this.layoutVersion = HdfsConstants.LAYOUT_VERSION;
+    this.layoutVersion = HdfsConstants.DATANODE_LAYOUT_VERSION;
     assert this.namespaceID == nsInfo.getNamespaceID() 
         : "Data-node and name-node layout versions must be the same.";
     this.cTime = nsInfo.getCTime();
     writeProperties(bpSd);
     
-    // 4.rename <SD>/curernt/<bpid>/previous.tmp to <SD>/curernt/<bpid>/previous
+    // 4.rename <SD>/current/<bpid>/previous.tmp to
+    // <SD>/current/<bpid>/previous
     rename(bpTmpDir, bpPrevDir);
     LOG.info("Upgrade of block pool " + blockpoolID + " at " + bpSd.getRoot()
         + " is complete");
@@ -349,7 +362,8 @@ public class BlockPoolSliceStorage extends Storage {
    * @throws IOException if the directory is not empty or it can not be removed
    */
   private void cleanupDetachDir(File detachDir) throws IOException {
-    if (!LayoutVersion.supports(Feature.APPEND_RBW_DIR, layoutVersion)
+    if (!DataNodeLayoutVersion.supports(
+        LayoutVersion.Feature.APPEND_RBW_DIR, layoutVersion)
         && detachDir.exists() && detachDir.isDirectory()) {
 
       if (FileUtil.list(detachDir).length != 0) {
@@ -363,6 +377,43 @@ public class BlockPoolSliceStorage extends Storage {
     }
   }
 
+  /**
+   * Restore all files from the trash directory to their corresponding
+   * locations under current/
+   */
+  private int restoreBlockFilesFromTrash(File trashRoot)
+      throws  IOException {
+    int filesRestored = 0;
+    File[] children = trashRoot.exists() ? trashRoot.listFiles() : null;
+    if (children == null) {
+      return 0;
+    }
+
+    File restoreDirectory = null;
+    for (File child : children) {
+      if (child.isDirectory()) {
+        // Recurse to process subdirectories.
+        filesRestored += restoreBlockFilesFromTrash(child);
+        continue;
+      }
+
+      if (restoreDirectory == null) {
+        restoreDirectory = new File(getRestoreDirectory(child));
+        if (!restoreDirectory.exists() && !restoreDirectory.mkdirs()) {
+          throw new IOException("Failed to create directory " + restoreDirectory);
+        }
+      }
+
+      final File newChild = new File(restoreDirectory, child.getName());
+      if (!child.renameTo(newChild)) {
+        throw new IOException("Failed to rename " + child + " to " + newChild);
+      }
+      ++filesRestored;
+    }
+    FileUtil.fullyDelete(trashRoot);
+    return filesRestored;
+  }
+
   /*
    * Roll back to old snapshot at the block pool level
    * If previous directory exists: 
@@ -389,13 +440,13 @@ public class BlockPoolSliceStorage extends Storage {
     // the namespace state or can be further upgraded to it.
     // In another word, we can only roll back when ( storedLV >= software LV)
     // && ( DN.previousCTime <= NN.ctime)
-    if (!(prevInfo.getLayoutVersion() >= HdfsConstants.LAYOUT_VERSION && 
+    if (!(prevInfo.getLayoutVersion() >= HdfsConstants.DATANODE_LAYOUT_VERSION && 
         prevInfo.getCTime() <= nsInfo.getCTime())) { // cannot rollback
       throw new InconsistentFSStateException(bpSd.getRoot(),
           "Cannot rollback to a newer state.\nDatanode previous state: LV = "
               + prevInfo.getLayoutVersion() + " CTime = " + prevInfo.getCTime()
               + " is newer than the namespace state: LV = "
-              + nsInfo.getLayoutVersion() + " CTime = " + nsInfo.getCTime());
+              + HdfsConstants.DATANODE_LAYOUT_VERSION + " CTime = " + nsInfo.getCTime());
     }
     
     LOG.info("Rolling back storage directory " + bpSd.getRoot()
@@ -478,9 +529,6 @@ public class BlockPoolSliceStorage extends Storage {
 
   /**
    * gets the data node storage directory based on block pool storage
-   * 
-   * @param bpRoot
-   * @return
    */
   private static String getDataNodeStorageRoot(String bpRoot) {
     Matcher matcher = BLOCK_POOL_PATH_PATTERN.matcher(bpRoot);
@@ -510,4 +558,66 @@ public class BlockPoolSliceStorage extends Storage {
   public boolean isPreUpgradableLayout(StorageDirectory sd) throws IOException {
     return false;
   }
+
+  private File getTrashRootDir(StorageDirectory sd) {
+    return new File(sd.getRoot(), TRASH_ROOT_DIR);
+  }
+
+  /**
+   * Get a target subdirectory under trash/ for a given block file that is being
+   * deleted.
+   *
+   * The subdirectory structure under trash/ mirrors that under current/ to keep
+   * implicit memory of where the files are to be restored (if necessary).
+   *
+   * @return the trash directory for a given block file that is being deleted.
+   */
+  public String getTrashDirectory(File blockFile) {
+    Matcher matcher = BLOCK_POOL_CURRENT_PATH_PATTERN.matcher(blockFile.getParent());
+    String trashDirectory = matcher.replaceFirst("$1$2" + TRASH_ROOT_DIR + "$4");
+    return trashDirectory;
+  }
+
+  /**
+   * Get a target subdirectory under current/ for a given block file that is being
+   * restored from trash.
+   *
+   * The subdirectory structure under trash/ mirrors that under current/ to keep
+   * implicit memory of where the files are to be restored.
+   *
+   * @return the target directory to restore a previously deleted block file.
+   */
+  @VisibleForTesting
+  String getRestoreDirectory(File blockFile) {
+    Matcher matcher = BLOCK_POOL_TRASH_PATH_PATTERN.matcher(blockFile.getParent());
+    String restoreDirectory = matcher.replaceFirst("$1$2" + STORAGE_DIR_CURRENT + "$4");
+    LOG.info("Restoring " + blockFile + " to " + restoreDirectory);
+    return restoreDirectory;
+  }
+
+  /**
+   * Delete all files and directories in the trash directories.
+   */
+  public void restoreTrash() {
+    for (StorageDirectory sd : storageDirs) {
+      File trashRoot = getTrashRootDir(sd);
+      try {
+        restoreBlockFilesFromTrash(trashRoot);
+        FileUtil.fullyDelete(getTrashRootDir(sd));
+      } catch (IOException ioe) {
+        LOG.warn("Restoring trash failed for storage directory " + sd);
+      }
+    }
+  }
+
+  /** trash is enabled if at least one storage directory contains trash root */
+  @VisibleForTesting
+  public boolean trashEnabled() {
+    for (StorageDirectory sd : storageDirs) {
+      if (getTrashRootDir(sd).exists()) {
+        return true;
+      }
+    }
+    return false;
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockReceiver.java

@@ -23,8 +23,10 @@ import java.io.BufferedOutputStream;
 import java.io.Closeable;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
+import java.io.File;
 import java.io.FileDescriptor;
 import java.io.FileOutputStream;
+import java.io.FileWriter;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
@@ -45,6 +47,7 @@ import org.apache.hadoop.hdfs.protocol.datatransfer.PipelineAck;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.Status;
 import org.apache.hadoop.hdfs.server.datanode.fsdataset.ReplicaInputStreams;
 import org.apache.hadoop.hdfs.server.datanode.fsdataset.ReplicaOutputStreams;
+import org.apache.hadoop.hdfs.server.datanode.ReplicaInPipeline;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
 import org.apache.hadoop.hdfs.util.DataTransferThrottler;
 import org.apache.hadoop.io.IOUtils;
@@ -52,6 +55,7 @@ import org.apache.hadoop.io.nativeio.NativeIO;
 import org.apache.hadoop.util.Daemon;
 import org.apache.hadoop.util.DataChecksum;
 import org.apache.hadoop.util.StringUtils;
+import org.apache.hadoop.util.Time;
 
 import com.google.common.annotations.VisibleForTesting;
 
@@ -116,6 +120,7 @@ class BlockReceiver implements Closeable {
   private final boolean isTransfer;
 
   private boolean syncOnClose;
+  private long restartBudget;
 
   BlockReceiver(final ExtendedBlock block, final DataInputStream in,
       final String inAddr, final String myAddr,
@@ -135,6 +140,7 @@ class BlockReceiver implements Closeable {
       this.clientname = clientname;
       this.isDatanode = clientname.length() == 0;
       this.isClient = !this.isDatanode;
+      this.restartBudget = datanode.getDnConf().restartReplicaExpiry;
 
       //for datanode, we have
       //1: clientName.length() == 0, and
@@ -723,19 +729,71 @@ class BlockReceiver implements Closeable {
       }
 
     } catch (IOException ioe) {
-      LOG.info("Exception for " + block, ioe);
-      throw ioe;
+      if (datanode.isRestarting()) {
+        // Do not throw if shutting down for restart. Otherwise, it will cause
+        // premature termination of responder.
+        LOG.info("Shutting down for restart (" + block + ").");
+      } else {
+        LOG.info("Exception for " + block, ioe);
+        throw ioe;
+      }
     } finally {
-      if (!responderClosed) { // Abnormal termination of the flow above
-        IOUtils.closeStream(this);
+      // Clear the previous interrupt state of this thread.
+      Thread.interrupted();
+
+      // If a shutdown for restart was initiated, upstream needs to be notified.
+      // There is no need to do anything special if the responder was closed
+      // normally.
+      if (!responderClosed) { // Data transfer was not complete.
         if (responder != null) {
+          // In case this datanode is shutting down for quick restart,
+          // send a special ack upstream.
+          if (datanode.isRestarting() && isClient && !isTransfer) {
+            File blockFile = ((ReplicaInPipeline)replicaInfo).getBlockFile();
+            File restartMeta = new File(blockFile.getParent()  + 
+                File.pathSeparator + "." + blockFile.getName() + ".restart");
+            if (restartMeta.exists() && !restartMeta.delete()) {
+              LOG.warn("Failed to delete restart meta file: " +
+                  restartMeta.getPath());
+            }
+            try {
+              FileWriter out = new FileWriter(restartMeta);
+              // write out the current time.
+              out.write(Long.toString(Time.now() + restartBudget));
+              out.flush();
+              out.close();
+            } catch (IOException ioe) {
+              // The worst case is not recovering this RBW replica. 
+              // Client will fall back to regular pipeline recovery.
+            }
+            try {
+              ((PacketResponder) responder.getRunnable()).
+                  sendOOBResponse(PipelineAck.getRestartOOBStatus());
+              // Even if the connection is closed after the ack packet is
+              // flushed, the client can react to the connection closure 
+              // first. Insert a delay to lower the chance of client 
+              // missing the OOB ack.
+              Thread.sleep(1000);
+            } catch (InterruptedException ie) {
+              // It is already going down. Ignore this.
+            } catch (IOException ioe) {
+              LOG.info("Error sending OOB Ack.", ioe);
+            }
+          }
           responder.interrupt();
         }
+        IOUtils.closeStream(this);
         cleanupBlock();
       }
       if (responder != null) {
         try {
-          responder.join(datanode.getDnConf().getXceiverStopTimeout());
+          responder.interrupt();
+          // join() on the responder should timeout a bit earlier than the
+          // configured deadline. Otherwise, the join() on this thread will
+          // likely timeout as well.
+          long joinTimeout = datanode.getDnConf().getXceiverStopTimeout();
+          joinTimeout = joinTimeout > 1  ? joinTimeout*8/10 : joinTimeout;
+          responder.join(joinTimeout);
           if (responder.isAlive()) {
             String msg = "Join on responder thread " + responder
                 + " timed out";
@@ -744,7 +802,10 @@ class BlockReceiver implements Closeable {
           }
         } catch (InterruptedException e) {
           responder.interrupt();
-          throw new IOException("Interrupted receiveBlock");
+          // do not throw if shutting down for restart.
+          if (!datanode.isRestarting()) {
+            throw new IOException("Interrupted receiveBlock");
+          }
         }
         responder = null;
       }
@@ -862,6 +923,7 @@ class BlockReceiver implements Closeable {
     private final PacketResponderType type;
     /** for log and error messages */
     private final String myString; 
+    private boolean sending = false;
 
     @Override
     public String toString() {
@@ -887,7 +949,9 @@ class BlockReceiver implements Closeable {
     }
 
     private boolean isRunning() {
-      return running && datanode.shouldRun;
+      // When preparing for a restart, it should continue to run until
+      // interrupted by the receiver thread.
+      return running && (datanode.shouldRun || datanode.isRestarting());
     }
     
     /**
@@ -903,44 +967,97 @@ class BlockReceiver implements Closeable {
       if(LOG.isDebugEnabled()) {
         LOG.debug(myString + ": enqueue " + p);
       }
-      synchronized(this) {
+      synchronized(ackQueue) {
         if (running) {
           ackQueue.addLast(p);
-          notifyAll();
+          ackQueue.notifyAll();
+        }
+      }
+    }
+
+    /**
+     * Send an OOB response. If all acks have been sent already for the block
+     * and the responder is about to close, the delivery is not guaranteed.
+     * This is because the other end can close the connection independently.
+     * An OOB coming from downstream will be automatically relayed upstream
+     * by the responder. This method is used only by originating datanode.
+     *
+     * @param ackStatus the type of ack to be sent
+     */
+    void sendOOBResponse(final Status ackStatus) throws IOException,
+        InterruptedException {
+      if (!running) {
+        LOG.info("Cannot send OOB response " + ackStatus + 
+            ". Responder not running.");
+        return;
+      }
+
+      synchronized(this) {
+        if (sending) {
+          wait(PipelineAck.getOOBTimeout(ackStatus));
+          // Didn't get my turn in time. Give up.
+          if (sending) {
+            throw new IOException("Could not send OOB reponse in time: "
+                + ackStatus);
+          }
+        }
+        sending = true;
+      }
+
+      LOG.info("Sending an out of band ack of type " + ackStatus);
+      try {
+        sendAckUpstreamUnprotected(null, PipelineAck.UNKOWN_SEQNO, 0L, 0L,
+            ackStatus);
+      } finally {
+        // Let others send ack. Unless there are miltiple OOB send
+        // calls, there can be only one waiter, the responder thread.
+        // In any case, only one needs to be notified.
+        synchronized(this) {
+          sending = false;
+          notify();
         }
       }
     }
     
     /** Wait for a packet with given {@code seqno} to be enqueued to ackQueue */
-    synchronized Packet waitForAckHead(long seqno) throws InterruptedException {
-      while (isRunning() && ackQueue.size() == 0) {
-        if (LOG.isDebugEnabled()) {
-          LOG.debug(myString + ": seqno=" + seqno +
-                    " waiting for local datanode to finish write.");
+    Packet waitForAckHead(long seqno) throws InterruptedException {
+      synchronized(ackQueue) {
+        while (isRunning() && ackQueue.size() == 0) {
+          if (LOG.isDebugEnabled()) {
+            LOG.debug(myString + ": seqno=" + seqno +
+                      " waiting for local datanode to finish write.");
+          }
+          ackQueue.wait();
         }
-        wait();
+        return isRunning() ? ackQueue.getFirst() : null;
       }
-      return isRunning() ? ackQueue.getFirst() : null;
     }
 
     /**
      * wait for all pending packets to be acked. Then shutdown thread.
      */
     @Override
-    public synchronized void close() {
-      while (isRunning() && ackQueue.size() != 0) {
-        try {
-          wait();
-        } catch (InterruptedException e) {
-          running = false;
-          Thread.currentThread().interrupt();
+    public void close() {
+      synchronized(ackQueue) {
+        while (isRunning() && ackQueue.size() != 0) {
+          try {
+            ackQueue.wait();
+          } catch (InterruptedException e) {
+            running = false;
+            Thread.currentThread().interrupt();
+          }
         }
+        if(LOG.isDebugEnabled()) {
+          LOG.debug(myString + ": closing");
+        }
+        running = false;
+        ackQueue.notifyAll();
       }
-      if(LOG.isDebugEnabled()) {
-        LOG.debug(myString + ": closing");
+
+      synchronized(this) {
+        running = false;
+        notifyAll();
       }
-      running = false;
-      notifyAll();
     }
 
     /**
@@ -968,6 +1085,14 @@ class BlockReceiver implements Closeable {
               if (LOG.isDebugEnabled()) {
                 LOG.debug(myString + " got " + ack);
               }
+              // Process an OOB ACK.
+              Status oobStatus = ack.getOOBStatus();
+              if (oobStatus != null) {
+                LOG.info("Relaying an out of band ack of type " + oobStatus);
+                sendAckUpstream(ack, PipelineAck.UNKOWN_SEQNO, 0L, 0L,
+                    Status.SUCCESS);
+                continue;
+              }
               seqno = ack.getSeqno();
             }
             if (seqno != PipelineAck.UNKOWN_SEQNO
@@ -1025,6 +1150,9 @@ class BlockReceiver implements Closeable {
              * status back to the client because this datanode has a problem.
              * The upstream datanode will detect that this datanode is bad, and
              * rightly so.
+             *
+             * The receiver thread can also interrupt this thread for sending
+             * an out-of-band response upstream.
              */
             LOG.info(myString + ": Thread is interrupted.");
             running = false;
@@ -1094,17 +1222,64 @@ class BlockReceiver implements Closeable {
     }
     
     /**
+     * The wrapper for the unprotected version. This is only called by
+     * the responder's run() method.
+     *
      * @param ack Ack received from downstream
      * @param seqno sequence number of ack to be sent upstream
      * @param totalAckTimeNanos total ack time including all the downstream
      *          nodes
      * @param offsetInBlock offset in block for the data in packet
+     * @param myStatus the local ack status
      */
     private void sendAckUpstream(PipelineAck ack, long seqno,
         long totalAckTimeNanos, long offsetInBlock,
         Status myStatus) throws IOException {
+      try {
+        // Wait for other sender to finish. Unless there is an OOB being sent,
+        // the responder won't have to wait.
+        synchronized(this) {
+          while(sending) {
+            wait();
+          }
+          sending = true;
+        }
+
+        try {
+          if (!running) return;
+          sendAckUpstreamUnprotected(ack, seqno, totalAckTimeNanos,
+              offsetInBlock, myStatus);
+        } finally {
+          synchronized(this) {
+            sending = false;
+            notify();
+          }
+        }
+      } catch (InterruptedException ie) {
+        // The responder was interrupted. Make it go down without
+        // interrupting the receiver(writer) thread.  
+        running = false;
+      }
+    }
+
+    /**
+     * @param ack Ack received from downstream
+     * @param seqno sequence number of ack to be sent upstream
+     * @param totalAckTimeNanos total ack time including all the downstream
+     *          nodes
+     * @param offsetInBlock offset in block for the data in packet
+     * @param myStatus the local ack status
+     */
+    private void sendAckUpstreamUnprotected(PipelineAck ack, long seqno,
+        long totalAckTimeNanos, long offsetInBlock, Status myStatus)
+        throws IOException {
       Status[] replies = null;
-      if (mirrorError) { // ack read error
+      if (ack == null) {
+        // A new OOB response is being sent from this node. Regardless of
+        // downstream nodes, reply should contain one reply.
+        replies = new Status[1];
+        replies[0] = myStatus;
+      } else if (mirrorError) { // ack read error
         replies = MIRROR_ERROR_STATUS;
       } else {
         short ackLen = type == PacketResponderType.LAST_IN_PIPELINE ? 0 : ack
@@ -1130,7 +1305,6 @@ class BlockReceiver implements Closeable {
           && offsetInBlock > replicaInfo.getBytesAcked()) {
         replicaInfo.setBytesAcked(offsetInBlock);
       }
-
       // send my ack back to upstream datanode
       replyAck.write(upstreamOut);
       upstreamOut.flush();
@@ -1152,9 +1326,11 @@ class BlockReceiver implements Closeable {
      * 
      * This should be called only when the ack queue is not empty
      */
-    private synchronized void removeAckHead() {
-      ackQueue.removeFirst();
-      notifyAll();
+    private void removeAckHead() {
+      synchronized(ackQueue) {
+        ackQueue.removeFirst();
+        ackQueue.notifyAll();
+      }
     }
   }
   

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DNConf.java

@@ -46,6 +46,8 @@ import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_MIN_SUPPORTED_NA
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_ENCRYPT_DATA_TRANSFER_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_ENCRYPT_DATA_TRANSFER_DEFAULT;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATA_ENCRYPTION_ALGORITHM_KEY;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_RESTART_REPLICA_EXPIRY_KEY;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_RESTART_REPLICA_EXPIRY_DEFAULT;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
@@ -82,6 +84,7 @@ public class DNConf {
   final String encryptionAlgorithm;
   
   final long xceiverStopTimeout;
+  final long restartReplicaExpiry;
 
   final long maxLockedMemory;
 
@@ -157,6 +160,10 @@ public class DNConf {
     this.maxLockedMemory = conf.getLong(
         DFS_DATANODE_MAX_LOCKED_MEMORY_KEY,
         DFS_DATANODE_MAX_LOCKED_MEMORY_DEFAULT);
+
+    this.restartReplicaExpiry = conf.getLong(
+        DFS_DATANODE_RESTART_REPLICA_EXPIRY_KEY,
+        DFS_DATANODE_RESTART_REPLICA_EXPIRY_DEFAULT) * 1000L;
   }
   
   // We get minimumNameNodeVersion via a method so it can be mocked out in tests.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java

@@ -17,41 +17,10 @@
  */
 package org.apache.hadoop.hdfs.server.datanode;
 
-import static org.apache.hadoop.hdfs.DFSConfigKeys.*;
-import static org.apache.hadoop.util.ExitUtil.terminate;
-
-import java.io.BufferedOutputStream;
-import java.io.ByteArrayInputStream;
-import java.io.DataInputStream;
-import java.io.DataOutputStream;
-import java.io.FileInputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
-import java.io.PrintStream;
-import java.net.InetSocketAddress;
-import java.net.Socket;
-import java.net.SocketException;
-import java.net.SocketTimeoutException;
-import java.net.URI;
-import java.net.UnknownHostException;
-import java.nio.channels.ClosedByInterruptException;
-import java.nio.channels.ClosedChannelException;
-import java.nio.channels.SocketChannel;
-import java.security.PrivilegedExceptionAction;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.EnumSet;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
-import java.util.UUID;
-import java.util.concurrent.atomic.AtomicInteger;
-
-import javax.management.ObjectName;
-
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Joiner;
+import com.google.common.base.Preconditions;
+import com.google.protobuf.BlockingService;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
@@ -68,37 +37,15 @@ import org.apache.hadoop.hdfs.HDFSPolicyProvider;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.net.DomainPeerServer;
 import org.apache.hadoop.hdfs.net.TcpPeerServer;
-import org.apache.hadoop.hdfs.protocol.Block;
-import org.apache.hadoop.hdfs.protocol.BlockLocalPathInfo;
-import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
-import org.apache.hadoop.hdfs.protocol.DatanodeID;
-import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
-import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
-import org.apache.hadoop.hdfs.protocol.HdfsBlocksMetadata;
-import org.apache.hadoop.hdfs.protocol.HdfsConstants;
-import org.apache.hadoop.hdfs.protocol.RecoveryInProgressException;
-import org.apache.hadoop.hdfs.protocol.datatransfer.BlockConstructionStage;
-import org.apache.hadoop.hdfs.protocol.datatransfer.DataTransferEncryptor;
-import org.apache.hadoop.hdfs.protocol.datatransfer.DataTransferProtocol;
-import org.apache.hadoop.hdfs.protocol.datatransfer.IOStreamPair;
-import org.apache.hadoop.hdfs.protocol.datatransfer.Sender;
+import org.apache.hadoop.hdfs.protocol.*;
+import org.apache.hadoop.hdfs.protocol.datatransfer.*;
 import org.apache.hadoop.hdfs.protocol.proto.ClientDatanodeProtocolProtos.ClientDatanodeProtocolService;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.DNTransferAckProto;
 import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.Status;
 import org.apache.hadoop.hdfs.protocol.proto.InterDatanodeProtocolProtos.InterDatanodeProtocolService;
-import org.apache.hadoop.hdfs.protocolPB.ClientDatanodeProtocolPB;
-import org.apache.hadoop.hdfs.protocolPB.ClientDatanodeProtocolServerSideTranslatorPB;
-import org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolClientSideTranslatorPB;
-import org.apache.hadoop.hdfs.protocolPB.InterDatanodeProtocolPB;
-import org.apache.hadoop.hdfs.protocolPB.InterDatanodeProtocolServerSideTranslatorPB;
-import org.apache.hadoop.hdfs.protocolPB.InterDatanodeProtocolTranslatorPB;
-import org.apache.hadoop.hdfs.protocolPB.PBHelper;
-import org.apache.hadoop.hdfs.security.token.block.BlockPoolTokenSecretManager;
-import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
-import org.apache.hadoop.hdfs.security.token.block.BlockTokenSecretManager;
+import org.apache.hadoop.hdfs.protocolPB.*;
+import org.apache.hadoop.hdfs.security.token.block.*;
 import org.apache.hadoop.hdfs.security.token.block.BlockTokenSecretManager.AccessMode;
-import org.apache.hadoop.hdfs.security.token.block.ExportedBlockKeys;
-import org.apache.hadoop.hdfs.security.token.block.InvalidBlockTokenException;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.ReplicaState;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
@@ -112,11 +59,7 @@ import org.apache.hadoop.hdfs.server.datanode.web.resources.DatanodeWebHdfsMetho
 import org.apache.hadoop.hdfs.server.namenode.FileChecksumServlets;
 import org.apache.hadoop.hdfs.server.namenode.StreamFile;
 import org.apache.hadoop.hdfs.server.protocol.BlockRecoveryCommand.RecoveringBlock;
-import org.apache.hadoop.hdfs.server.protocol.DatanodeProtocol;
-import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
-import org.apache.hadoop.hdfs.server.protocol.InterDatanodeProtocol;
-import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
-import org.apache.hadoop.hdfs.server.protocol.ReplicaRecoveryInfo;
+import org.apache.hadoop.hdfs.server.protocol.*;
 import org.apache.hadoop.hdfs.web.WebHdfsFileSystem;
 import org.apache.hadoop.hdfs.web.resources.Param;
 import org.apache.hadoop.http.HttpConfig;
@@ -139,21 +82,24 @@ import org.apache.hadoop.security.UserGroupInformation.AuthenticationMethod;
 import org.apache.hadoop.security.authorize.AccessControlList;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.security.token.TokenIdentifier;
-import org.apache.hadoop.util.Daemon;
-import org.apache.hadoop.util.DiskChecker;
+import org.apache.hadoop.util.*;
 import org.apache.hadoop.util.DiskChecker.DiskErrorException;
 import org.apache.hadoop.util.DiskChecker.DiskOutOfSpaceException;
-import org.apache.hadoop.util.GenericOptionsParser;
-import org.apache.hadoop.util.JvmPauseMonitor;
-import org.apache.hadoop.util.ServicePlugin;
-import org.apache.hadoop.util.StringUtils;
-import org.apache.hadoop.util.VersionInfo;
 import org.mortbay.util.ajax.JSON;
 
-import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Joiner;
-import com.google.common.base.Preconditions;
-import com.google.protobuf.BlockingService;
+import javax.management.ObjectName;
+import java.io.*;
+import java.lang.management.ManagementFactory;
+import java.net.*;
+import java.nio.channels.ClosedByInterruptException;
+import java.nio.channels.ClosedChannelException;
+import java.nio.channels.SocketChannel;
+import java.security.PrivilegedExceptionAction;
+import java.util.*;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.apache.hadoop.hdfs.DFSConfigKeys.*;
+import static org.apache.hadoop.util.ExitUtil.terminate;
 
 /**********************************************************
  * DataNode is a class (and program) that stores a set of
@@ -210,7 +156,14 @@ public class DataNode extends Configured
   static final Log ClientTraceLog =
     LogFactory.getLog(DataNode.class.getName() + ".clienttrace");
   
-  private static final String USAGE = "Usage: java DataNode [-rollback | -regular]";
+  private static final String USAGE =
+      "Usage: java DataNode [-regular | -rollback | -rollingupgrade rollback]\n" +
+      "    -regular                 : Normal DataNode startup (default).\n" +
+      "    -rollback                : Rollback a standard upgrade.\n" +
+      "    -rollingupgrade rollback : Rollback a rolling upgrade operation.\n" +
+      "  Refer to HDFS documentation for the difference between standard\n" +
+      "  and rolling upgrades.";
+
   static final int CURRENT_BLOCK_FORMAT_VERSION = 1;
 
   /**
@@ -222,6 +175,8 @@ public class DataNode extends Configured
   }
   
   volatile boolean shouldRun = true;
+  volatile boolean shutdownForUpgrade = false;
+  private boolean shutdownInProgress = false;
   private BlockPoolManager blockPoolManager;
   volatile FsDatasetSpi<? extends FsVolumeSpi> data = null;
   private String clusterId = null;
@@ -265,6 +220,7 @@ public class DataNode extends Configured
   private SecureResources secureResources = null;
   private List<StorageLocation> dataDirs;
   private Configuration conf;
+  private String confVersion;
   private final long maxNumberOfBlocksToLog;
 
   private final List<String> usersWithLocalPathAccess;
@@ -293,6 +249,11 @@ public class DataNode extends Configured
         DFSConfigKeys.DFS_HDFS_BLOCKS_METADATA_ENABLED, 
         DFSConfigKeys.DFS_HDFS_BLOCKS_METADATA_ENABLED_DEFAULT);
 
+    confVersion = "core-" +
+        conf.get("hadoop.common.configuration.version", "UNSPECIFIED") +
+        ",hdfs-" +
+        conf.get("hadoop.hdfs.configuration.version", "UNSPECIFIED");
+
     // Determine whether we should try to pass file descriptors to clients.
     if (conf.getBoolean(DFSConfigKeys.DFS_CLIENT_READ_SHORTCIRCUIT_KEY,
               DFSConfigKeys.DFS_CLIENT_READ_SHORTCIRCUIT_DEFAULT)) {
@@ -1234,9 +1195,31 @@ public class DataNode extends Configured
     // offerServices may be modified.
     BPOfferService[] bposArray = this.blockPoolManager == null ? null
         : this.blockPoolManager.getAllNamenodeThreads();
-    this.shouldRun = false;
+    // If shutdown is not for restart, set shouldRun to false early. 
+    if (!shutdownForUpgrade) {
+      shouldRun = false;
+    }
+
+    // When shutting down for restart, DataXceiverServer is interrupted
+    // in order to avoid any further acceptance of requests, but the peers
+    // for block writes are not closed until the clients are notified.
+    if (dataXceiverServer != null) {
+      ((DataXceiverServer) this.dataXceiverServer.getRunnable()).kill();
+      this.dataXceiverServer.interrupt();
+    }
+
+    // Record the time of initial notification
+    long timeNotified = Time.now();
+
+    if (localDataXceiverServer != null) {
+      ((DataXceiverServer) this.localDataXceiverServer.getRunnable()).kill();
+      this.localDataXceiverServer.interrupt();
+    }
+
+    // Terminate directory scanner and block scanner
     shutdownPeriodicScanners();
-    
+
+    // Stop the web server
     if (infoServer != null) {
       try {
         infoServer.stop();
@@ -1244,26 +1227,24 @@ public class DataNode extends Configured
         LOG.warn("Exception shutting down DataNode", e);
       }
     }
-    if (ipcServer != null) {
-      ipcServer.stop();
-    }
     if (pauseMonitor != null) {
       pauseMonitor.stop();
     }
+
+    // shouldRun is set to false here to prevent certain threads from exiting
+    // before the restart prep is done.
+    this.shouldRun = false;
     
-    if (dataXceiverServer != null) {
-      ((DataXceiverServer) this.dataXceiverServer.getRunnable()).kill();
-      this.dataXceiverServer.interrupt();
-    }
-    if (localDataXceiverServer != null) {
-      ((DataXceiverServer) this.localDataXceiverServer.getRunnable()).kill();
-      this.localDataXceiverServer.interrupt();
-    }
     // wait for all data receiver threads to exit
     if (this.threadGroup != null) {
       int sleepMs = 2;
       while (true) {
-        this.threadGroup.interrupt();
+        // When shutting down for restart, wait 2.5 seconds before forcing
+        // termination of receiver threads.
+        if (!this.shutdownForUpgrade || 
+            (this.shutdownForUpgrade && (Time.now() - timeNotified > 2500))) {
+          this.threadGroup.interrupt();
+        }
         LOG.info("Waiting for threadgroup to exit, active threads is " +
                  this.threadGroup.activeCount());
         if (this.threadGroup.activeCount() == 0) {
@@ -1293,7 +1274,13 @@ public class DataNode extends Configured
       } catch (InterruptedException ie) {
       }
     }
-    
+   
+   // IPC server needs to be shutdown late in the process, otherwise
+   // shutdown command response won't get sent.
+   if (ipcServer != null) {
+      ipcServer.stop();
+    }
+
     if(blockPoolManager != null) {
       try {
         this.blockPoolManager.shutDownAll(bposArray);
@@ -1320,6 +1307,13 @@ public class DataNode extends Configured
       dataNodeInfoBeanName = null;
     }
     if (shortCircuitRegistry != null) shortCircuitRegistry.shutdown();
+    LOG.info("Shutdown complete.");
+    synchronized(this) {
+      // it is already false, but setting it again to avoid a findbug warning.
+      this.shouldRun = false;
+      // Notify the main thread.
+      notifyAll();
+    }
   }
   
   
@@ -1792,6 +1786,7 @@ public class DataNode extends Configured
   /** Instantiate & Start a single datanode daemon and wait for it to finish.
    *  If this thread is specifically interrupted, it will stop waiting.
    */
+  @VisibleForTesting
   public static DataNode createDataNode(String args[],
                                  Configuration conf) throws IOException {
     return createDataNode(args, conf, null);
@@ -1800,6 +1795,7 @@ public class DataNode extends Configured
   /** Instantiate & Start a single datanode daemon and wait for it to finish.
    *  If this thread is specifically interrupted, it will stop waiting.
    */
+  @VisibleForTesting
   @InterfaceAudience.Private
   public static DataNode createDataNode(String args[], Configuration conf,
       SecureResources resources) throws IOException {
@@ -1818,7 +1814,11 @@ public class DataNode extends Configured
             && blockPoolManager.getAllNamenodeThreads().length == 0) {
           shouldRun = false;
         }
-        Thread.sleep(2000);
+        // Terminate if shutdown is complete or 2 seconds after all BPs
+        // are shutdown.
+        synchronized(this) {
+          wait(2000);
+        }
       } catch (InterruptedException ex) {
         LOG.warn("Received exception in Datanode#join: " + ex);
       }
@@ -1910,25 +1910,28 @@ public class DataNode extends Configured
    *
    * @return false if passed argements are incorrect
    */
-  private static boolean parseArguments(String args[], 
-                                        Configuration conf) {
-    int argsLen = (args == null) ? 0 : args.length;
+  @VisibleForTesting
+  static boolean parseArguments(String args[], Configuration conf) {
     StartupOption startOpt = StartupOption.REGULAR;
-    for(int i=0; i < argsLen; i++) {
-      String cmd = args[i];
+    int i = 0;
+
+    if (args != null && args.length != 0) {
+      String cmd = args[i++];
       if ("-r".equalsIgnoreCase(cmd) || "--rack".equalsIgnoreCase(cmd)) {
         LOG.error("-r, --rack arguments are not supported anymore. RackID " +
             "resolution is handled by the NameNode.");
-        terminate(1);
-      } else if ("-rollback".equalsIgnoreCase(cmd)) {
+        return false;
+      } else if (StartupOption.ROLLBACK.getName().equalsIgnoreCase(cmd)) {
         startOpt = StartupOption.ROLLBACK;
-      } else if ("-regular".equalsIgnoreCase(cmd)) {
+      } else if (StartupOption.REGULAR.getName().equalsIgnoreCase(cmd)) {
         startOpt = StartupOption.REGULAR;
-      } else
+      } else {
         return false;
+      }
     }
+
     setStartupOption(conf, startOpt);
-    return true;
+    return (args == null || i == args.length);    // Fail if more than one cmd specified!
   }
 
   private static void setStartupOption(Configuration conf, StartupOption opt) {
@@ -1936,8 +1939,9 @@ public class DataNode extends Configured
   }
 
   static StartupOption getStartupOption(Configuration conf) {
-    return StartupOption.valueOf(conf.get(DFS_DATANODE_STARTUP_KEY,
-                                          StartupOption.REGULAR.toString()));
+    String value = conf.get(DFS_DATANODE_STARTUP_KEY,
+                            StartupOption.REGULAR.toString());
+    return StartupOption.getEnum(value);
   }
 
   /**
@@ -1968,11 +1972,15 @@ public class DataNode extends Configured
 
 
   public static void secureMain(String args[], SecureResources resources) {
+    int errorCode = 0;
     try {
       StringUtils.startupShutdownMessage(DataNode.class, args, LOG);
       DataNode datanode = createDataNode(args, null, resources);
-      if (datanode != null)
+      if (datanode != null) {
         datanode.join();
+      } else {
+        errorCode = 1;
+      }
     } catch (Throwable e) {
       LOG.fatal("Exception in secureMain", e);
       terminate(1, e);
@@ -1982,7 +1990,7 @@ public class DataNode extends Configured
       // condition was not met. Also, In secure mode, control will go to Jsvc
       // and Datanode process hangs if it does not exit.
       LOG.warn("Exiting Datanode");
-      terminate(0);
+      terminate(errorCode);
     }
   }
   
@@ -2446,6 +2454,43 @@ public class DataNode extends Configured
     data.deleteBlockPool(blockPoolId, force);
   }
 
+  @Override // ClientDatanodeProtocol
+  public synchronized void shutdownDatanode(boolean forUpgrade) throws IOException {
+    LOG.info("shutdownDatanode command received (upgrade=" + forUpgrade +
+        "). Shutting down Datanode...");
+
+    // Shutdown can be called only once.
+    if (shutdownInProgress) {
+      throw new IOException("Shutdown already in progress.");
+    }
+    shutdownInProgress = true;
+    shutdownForUpgrade = forUpgrade;
+
+    // Asynchronously start the shutdown process so that the rpc response can be
+    // sent back.
+    Thread shutdownThread = new Thread() {
+      @Override public void run() {
+        if (!shutdownForUpgrade) {
+          // Delay the shutdown a bit if not doing for restart.
+          try {
+            Thread.sleep(1000);
+          } catch (InterruptedException ie) { }
+        }
+        shutdown();
+      }
+    };
+
+    shutdownThread.setDaemon(true);
+    shutdownThread.start();
+  }
+
+  @Override //ClientDatanodeProtocol
+  public DatanodeLocalInfo getDatanodeInfo() {
+    long uptime = ManagementFactory.getRuntimeMXBean().getUptime()/1000;
+    return new DatanodeLocalInfo(VersionInfo.getVersion(),
+        confVersion, uptime);
+  }
+
   /**
    * @param addr rpc address of the namenode
    * @return true if the datanode is connected to a NameNode at the
@@ -2471,6 +2516,10 @@ public class DataNode extends Configured
     return bp != null ? bp.isAlive() : false;
   }
 
+  boolean isRestarting() {
+    return shutdownForUpgrade;
+  }
+
   /**
    * A datanode is considered to be fully started if all the BP threads are
    * alive and all the block pools are initialized.
@@ -2519,6 +2568,11 @@ public class DataNode extends Configured
     return shouldRun;
   }
 
+  @VisibleForTesting
+  DataStorage getStorage() {
+    return storage;
+  }
+
   public ShortCircuitRegistry getShortCircuitRegistry() {
     return shortCircuitRegistry;
   }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNodeLayoutVersion.java

@@ -0,0 +1,97 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.server.datanode;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.SortedSet;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.hdfs.protocol.LayoutVersion;
+import org.apache.hadoop.hdfs.protocol.LayoutVersion.FeatureInfo;
+import org.apache.hadoop.hdfs.protocol.LayoutVersion.LayoutFeature;
+
+@InterfaceAudience.Private
+public class DataNodeLayoutVersion {  
+  /** Build layout version and corresponding feature matrix */
+  public final static Map<Integer, SortedSet<LayoutFeature>> FEATURES = 
+    new HashMap<Integer, SortedSet<LayoutFeature>>();
+  
+  public static final int CURRENT_LAYOUT_VERSION
+      = LayoutVersion.getCurrentLayoutVersion(Feature.values());
+
+  static{
+    LayoutVersion.updateMap(FEATURES, LayoutVersion.Feature.values());
+    LayoutVersion.updateMap(FEATURES, DataNodeLayoutVersion.Feature.values());
+  }
+  
+  public static SortedSet<LayoutFeature> getFeatures(int lv) {
+    return FEATURES.get(lv);
+  }
+
+  public static boolean supports(final LayoutFeature f, final int lv) {
+    return LayoutVersion.supports(FEATURES, f, lv);
+  }
+
+  /**
+   * Enums for features that change the layout version.
+   * <br><br>
+   * To add a new layout version:
+   * <ul>
+   * <li>Define a new enum constant with a short enum name, the new layout version 
+   * and description of the added feature.</li>
+   * <li>When adding a layout version with an ancestor that is not same as
+   * its immediate predecessor, use the constructor where a specific ancestor
+   * can be passed.
+   * </li>
+   * </ul>
+   */
+  public static enum Feature implements LayoutFeature {
+    FIRST_LAYOUT(-55, -53, "First datenode layout", false);
+   
+    private final FeatureInfo info;
+
+    /**
+     * DataNodeFeature that is added at layout version {@code lv} - 1. 
+     * @param lv new layout version with the addition of this feature
+     * @param description description of the feature
+     */
+    Feature(final int lv, final String description) {
+      this(lv, lv + 1, description, false);
+    }
+
+    /**
+     * DataNode feature that is added at layout version {@code ancestoryLV}.
+     * @param lv new layout version with the addition of this feature
+     * @param ancestorLV layout version from which the new lv is derived from.
+     * @param description description of the feature
+     * @param reserved true when this is a layout version reserved for previous
+     *        version
+     * @param features set of features that are to be enabled for this version
+     */
+    Feature(final int lv, final int ancestorLV, final String description,
+        boolean reserved, Feature... features) {
+      info = new FeatureInfo(lv, ancestorLV, description, reserved, features);
+    }
+    
+    @Override
+    public FeatureInfo getInfo() {
+      return info;
+    }
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java

@@ -18,27 +18,15 @@
 
 package org.apache.hadoop.hdfs.server.datanode;
 
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.RandomAccessFile;
-import java.nio.channels.FileLock;
-import java.util.*;
-
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileSystem;
-import org.apache.hadoop.fs.FileUtil;
-import org.apache.hadoop.fs.HardLink;
-import org.apache.hadoop.fs.LocalFileSystem;
-import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.*;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
-import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NodeType;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
 import org.apache.hadoop.hdfs.server.common.InconsistentFSStateException;
@@ -50,6 +38,11 @@ import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.util.Daemon;
 import org.apache.hadoop.util.DiskChecker;
 
+import java.io.*;
+import java.nio.channels.FileLock;
+import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
+
 /** 
  * Data storage information file.
  * <p>
@@ -66,6 +59,13 @@ public class DataStorage extends Storage {
   public final static String STORAGE_DIR_FINALIZED = "finalized";
   public final static String STORAGE_DIR_TMP = "tmp";
 
+  // Set of bpids for which 'trash' is currently enabled.
+  // When trash is enabled block files are moved under a separate
+  // 'trash' folder instead of being deleted right away. This can
+  // be useful during rolling upgrades, for example.
+  // The set is backed by a concurrent HashMap.
+  private Set<String> trashEnabledBpids;
+
   /**
    * Datanode UUID that this storage is currently attached to. This
    *  is the same as the legacy StorageID for datanodes that were
@@ -84,14 +84,16 @@ public class DataStorage extends Storage {
 
   DataStorage() {
     super(NodeType.DATA_NODE);
+    trashEnabledBpids = Collections.newSetFromMap(
+        new ConcurrentHashMap<String, Boolean>());
   }
   
-  public StorageInfo getBPStorage(String bpid) {
+  public BlockPoolSliceStorage getBPStorage(String bpid) {
     return bpStorageMap.get(bpid);
   }
   
   public DataStorage(StorageInfo storageInfo) {
-    super(NodeType.DATA_NODE, storageInfo);
+    super(storageInfo);
   }
 
   public synchronized String getDatanodeUuid() {
@@ -108,6 +110,43 @@ public class DataStorage extends Storage {
       sd.setStorageUuid(DatanodeStorage.generateUuid());
     }
   }
+
+  /**
+   * Enable trash for the specified block pool storage.
+   */
+  public void enableTrash(String bpid) {
+    if (trashEnabledBpids.add(bpid)) {
+      LOG.info("Enabled trash for bpid " + bpid);
+    }
+  }
+
+  public void restoreTrash(String bpid) {
+    if (trashEnabledBpids.contains(bpid)) {
+      getBPStorage(bpid).restoreTrash();
+      trashEnabledBpids.remove(bpid);
+      LOG.info("Restored trash for bpid " + bpid);
+    }
+  }
+
+  public boolean trashEnabled(String bpid) {
+    return trashEnabledBpids.contains(bpid);
+  }
+
+  /**
+   * If rolling upgrades are in progress then do not delete block files
+   * immediately. Instead we move the block files to an intermediate
+   * 'trash' directory. If there is a subsequent rollback, then the block
+   * files will be restored from trash.
+   *
+   * @return trash directory if rolling upgrade is in progress, null
+   *         otherwise.
+   */
+  public String getTrashDirectoryForBlockFile(String bpid, File blockFile) {
+    if (trashEnabledBpids.contains(bpid)) {
+      return ((BlockPoolSliceStorage) getBPStorage(bpid)).getTrashDirectory(blockFile);
+    }
+    return null;
+  }
   
   /**
    * Analyze storage directories.
@@ -131,10 +170,8 @@ public class DataStorage extends Storage {
       // DN storage has been initialized, no need to do anything
       return;
     }
-    assert HdfsConstants.LAYOUT_VERSION == nsInfo.getLayoutVersion() :
-      "Data-node version " + HdfsConstants.LAYOUT_VERSION + 
-      " and name-node layout version " + nsInfo.getLayoutVersion() + 
-      " must be the same.";
+    LOG.info("Data-node version: " + HdfsConstants.DATANODE_LAYOUT_VERSION
+        + " and name-node layout version: " + nsInfo.getLayoutVersion());
     
     // 1. For each data directory calculate its state and 
     // check whether all is consistent before transitioning.
@@ -186,15 +223,13 @@ public class DataStorage extends Storage {
     // while others could be uptodate for the regular startup.
     for(int idx = 0; idx < getNumStorageDirs(); idx++) {
       doTransition(datanode, getStorageDir(idx), nsInfo, startOpt);
-      assert this.getLayoutVersion() == nsInfo.getLayoutVersion() :
-        "Data-node and name-node layout versions must be the same.";
       createStorageID(getStorageDir(idx));
     }
     
     // 3. Update all storages. Some of them might have just been formatted.
     this.writeAll();
     
-    // 4. mark DN storage is initilized
+    // 4. mark DN storage is initialized
     this.initialized = true;
   }
 
@@ -261,7 +296,7 @@ public class DataStorage extends Storage {
   void format(StorageDirectory sd, NamespaceInfo nsInfo,
               String datanodeUuid) throws IOException {
     sd.clearDirectory(); // create directory
-    this.layoutVersion = HdfsConstants.LAYOUT_VERSION;
+    this.layoutVersion = HdfsConstants.DATANODE_LAYOUT_VERSION;
     this.clusterID = nsInfo.getClusterID();
     this.namespaceID = nsInfo.getNamespaceID();
     this.cTime = 0;
@@ -297,7 +332,8 @@ public class DataStorage extends Storage {
     }
 
     // Set NamespaceID in version before federation
-    if (!LayoutVersion.supports(Feature.FEDERATION, layoutVersion)) {
+    if (!DataNodeLayoutVersion.supports(
+        LayoutVersion.Feature.FEDERATION, layoutVersion)) {
       props.setProperty("namespaceID", String.valueOf(namespaceID));
     }
   }
@@ -321,11 +357,12 @@ public class DataStorage extends Storage {
       setLayoutVersion(props, sd);
     }
     setcTime(props, sd);
-    setStorageType(props, sd);
+    checkStorageType(props, sd);
     setClusterId(props, layoutVersion, sd);
     
     // Read NamespaceID in version before federation
-    if (!LayoutVersion.supports(Feature.FEDERATION, layoutVersion)) {
+    if (!DataNodeLayoutVersion.supports(
+        LayoutVersion.Feature.FEDERATION, layoutVersion)) {
       setNamespaceID(props, sd);
     }
     
@@ -414,11 +451,12 @@ public class DataStorage extends Storage {
     }
     readProperties(sd);
     checkVersionUpgradable(this.layoutVersion);
-    assert this.layoutVersion >= HdfsConstants.LAYOUT_VERSION :
+    assert this.layoutVersion >= HdfsConstants.DATANODE_LAYOUT_VERSION :
       "Future version is not allowed";
     
     boolean federationSupported = 
-      LayoutVersion.supports(Feature.FEDERATION, layoutVersion);
+      DataNodeLayoutVersion.supports(
+          LayoutVersion.Feature.FEDERATION, layoutVersion);
     // For pre-federation version - validate the namespaceID
     if (!federationSupported &&
         getNamespaceID() != nsInfo.getNamespaceID()) {
@@ -440,24 +478,22 @@ public class DataStorage extends Storage {
     // meaningful at BlockPoolSliceStorage level. 
 
     // regular start up. 
-    if (this.layoutVersion == HdfsConstants.LAYOUT_VERSION)
+    if (this.layoutVersion == HdfsConstants.DATANODE_LAYOUT_VERSION)
       return; // regular startup
     
     // do upgrade
-    if (this.layoutVersion > HdfsConstants.LAYOUT_VERSION) {
+    if (this.layoutVersion > HdfsConstants.DATANODE_LAYOUT_VERSION) {
       doUpgrade(sd, nsInfo);  // upgrade
       return;
     }
     
-    // layoutVersion < LAYOUT_VERSION. I.e. stored layout version is newer
+    // layoutVersion < DATANODE_LAYOUT_VERSION. I.e. stored layout version is newer
     // than the version supported by datanode. This should have been caught
     // in readProperties(), even if rollback was not carried out or somehow
     // failed.
     throw new IOException("BUG: The stored LV = " + this.getLayoutVersion()
-                          + " is newer than the supported LV = "
-                          + HdfsConstants.LAYOUT_VERSION
-                          + " or name node LV = "
-                          + nsInfo.getLayoutVersion());
+        + " is newer than the supported LV = "
+        + HdfsConstants.DATANODE_LAYOUT_VERSION);
   }
 
   /**
@@ -485,12 +521,14 @@ public class DataStorage extends Storage {
   void doUpgrade(StorageDirectory sd, NamespaceInfo nsInfo) throws IOException {
     // If the existing on-disk layout version supportes federation, simply
     // update its layout version.
-    if (LayoutVersion.supports(Feature.FEDERATION, layoutVersion)) {
+    if (DataNodeLayoutVersion.supports(
+        LayoutVersion.Feature.FEDERATION, layoutVersion)) {
       // The VERSION file is already read in. Override the layoutVersion 
       // field and overwrite the file.
       LOG.info("Updating layout version from " + layoutVersion + " to "
-          + nsInfo.getLayoutVersion() + " for storage " + sd.getRoot());
-      layoutVersion = nsInfo.getLayoutVersion();
+          + HdfsConstants.DATANODE_LAYOUT_VERSION + " for storage "
+          + sd.getRoot());
+      layoutVersion = HdfsConstants.DATANODE_LAYOUT_VERSION;
       writeProperties(sd);
       return;
     }
@@ -498,7 +536,7 @@ public class DataStorage extends Storage {
     LOG.info("Upgrading storage directory " + sd.getRoot()
              + ".\n   old LV = " + this.getLayoutVersion()
              + "; old CTime = " + this.getCTime()
-             + ".\n   new LV = " + nsInfo.getLayoutVersion()
+             + ".\n   new LV = " + HdfsConstants.DATANODE_LAYOUT_VERSION
              + "; new CTime = " + nsInfo.getCTime());
     
     File curDir = sd.getCurrentDir();
@@ -528,7 +566,7 @@ public class DataStorage extends Storage {
     linkAllBlocks(tmpDir, bbwDir, new File(curBpDir, STORAGE_DIR_CURRENT));
     
     // 4. Write version file under <SD>/current
-    layoutVersion = HdfsConstants.LAYOUT_VERSION;
+    layoutVersion = HdfsConstants.DATANODE_LAYOUT_VERSION;
     clusterID = nsInfo.getClusterID();
     writeProperties(sd);
     
@@ -548,7 +586,8 @@ public class DataStorage extends Storage {
    * @throws IOException if the directory is not empty or it can not be removed
    */
   private void cleanupDetachDir(File detachDir) throws IOException {
-    if (!LayoutVersion.supports(Feature.APPEND_RBW_DIR, layoutVersion) &&
+    if (!DataNodeLayoutVersion.supports(
+        LayoutVersion.Feature.APPEND_RBW_DIR, layoutVersion) &&
         detachDir.exists() && detachDir.isDirectory() ) {
       
         if (FileUtil.list(detachDir).length != 0 ) {
@@ -584,19 +623,13 @@ public class DataStorage extends Storage {
     File prevDir = sd.getPreviousDir();
     // This is a regular startup or a post-federation rollback
     if (!prevDir.exists()) {
-      // The current datanode version supports federation and the layout
-      // version from namenode matches what the datanode supports. An invalid
-      // rollback may happen if namenode didn't rollback and datanode is
-      // running a wrong version.  But this will be detected in block pool
-      // level and the invalid VERSION content will be overwritten when
-      // the error is corrected and rollback is retried.
-      if (LayoutVersion.supports(Feature.FEDERATION,
-          HdfsConstants.LAYOUT_VERSION) && 
-          HdfsConstants.LAYOUT_VERSION == nsInfo.getLayoutVersion()) {
-        readProperties(sd, nsInfo.getLayoutVersion());
+      if (DataNodeLayoutVersion.supports(LayoutVersion.Feature.FEDERATION,
+          HdfsConstants.DATANODE_LAYOUT_VERSION)) {
+        readProperties(sd, HdfsConstants.DATANODE_LAYOUT_VERSION);
         writeProperties(sd);
-        LOG.info("Layout version rolled back to " +
-            nsInfo.getLayoutVersion() + " for storage " + sd.getRoot());
+        LOG.info("Layout version rolled back to "
+            + HdfsConstants.DATANODE_LAYOUT_VERSION + " for storage "
+            + sd.getRoot());
       }
       return;
     }
@@ -605,16 +638,17 @@ public class DataStorage extends Storage {
 
     // We allow rollback to a state, which is either consistent with
     // the namespace state or can be further upgraded to it.
-    if (!(prevInfo.getLayoutVersion() >= HdfsConstants.LAYOUT_VERSION
+    if (!(prevInfo.getLayoutVersion() >= HdfsConstants.DATANODE_LAYOUT_VERSION
           && prevInfo.getCTime() <= nsInfo.getCTime()))  // cannot rollback
       throw new InconsistentFSStateException(sd.getRoot(),
           "Cannot rollback to a newer state.\nDatanode previous state: LV = "
               + prevInfo.getLayoutVersion() + " CTime = " + prevInfo.getCTime()
               + " is newer than the namespace state: LV = "
-              + nsInfo.getLayoutVersion() + " CTime = " + nsInfo.getCTime());
+              + HdfsConstants.DATANODE_LAYOUT_VERSION + " CTime = "
+              + nsInfo.getCTime());
     LOG.info("Rolling back storage directory " + sd.getRoot()
-             + ".\n   target LV = " + nsInfo.getLayoutVersion()
-             + "; target CTime = " + nsInfo.getCTime());
+        + ".\n   target LV = " + HdfsConstants.DATANODE_LAYOUT_VERSION
+        + "; target CTime = " + nsInfo.getCTime());
     File tmpDir = sd.getRemovedTmp();
     assert !tmpDir.exists() : "removed.tmp directory must not exist.";
     // rename current to tmp
@@ -677,9 +711,11 @@ public class DataStorage extends Storage {
   
   /*
    * Finalize the upgrade for a block pool
+   * This also empties trash created during rolling upgrade and disables
+   * trash functionality.
    */
   void finalizeUpgrade(String bpID) throws IOException {
-    // To handle finalizing a snapshot taken at datanode level while 
+    // To handle finalizing a snapshot taken at datanode level while
     // upgrading to federation, if datanode level snapshot previous exists, 
     // then finalize it. Else finalize the corresponding BP.
     for (StorageDirectory sd : storageDirs) {
@@ -710,7 +746,8 @@ public class DataStorage extends Storage {
     HardLink hardLink = new HardLink();
     // do the link
     int diskLayoutVersion = this.getLayoutVersion();
-    if (LayoutVersion.supports(Feature.APPEND_RBW_DIR, diskLayoutVersion)) {
+    if (DataNodeLayoutVersion.supports(
+        LayoutVersion.Feature.APPEND_RBW_DIR, diskLayoutVersion)) {
       // hardlink finalized blocks in tmpDir/finalized
       linkBlocks(new File(fromDir, STORAGE_DIR_FINALIZED), 
           new File(toDir, STORAGE_DIR_FINALIZED), diskLayoutVersion, hardLink);

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataXceiver.java

@@ -166,8 +166,8 @@ class DataXceiver extends Receiver implements Runnable {
     int opsProcessed = 0;
     Op op = null;
 
-    dataXceiverServer.addPeer(peer);
     try {
+      dataXceiverServer.addPeer(peer, Thread.currentThread());
       peer.setWriteTimeout(datanode.getDnConf().socketWriteTimeout);
       InputStream input = socketIn;
       if ((!peer.hasSecureChannel()) && dnConf.encryptDataTransfer) {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataXceiverServer.java

@@ -20,8 +20,7 @@ package org.apache.hadoop.hdfs.server.datanode;
 import java.io.IOException;
 import java.net.SocketTimeoutException;
 import java.nio.channels.AsynchronousCloseException;
-import java.util.HashSet;
-import java.util.Set;
+import java.util.HashMap;
 
 import org.apache.commons.logging.Log;
 import org.apache.hadoop.conf.Configuration;
@@ -45,7 +44,8 @@ class DataXceiverServer implements Runnable {
   
   private final PeerServer peerServer;
   private final DataNode datanode;
-  private final Set<Peer> peers = new HashSet<Peer>();
+  private final HashMap<Peer, Thread> peers = new HashMap<Peer, Thread>();
+  private boolean closed = false;
   
   /**
    * Maximal number of concurrent xceivers per node.
@@ -127,7 +127,7 @@ class DataXceiverServer implements Runnable {
   @Override
   public void run() {
     Peer peer = null;
-    while (datanode.shouldRun) {
+    while (datanode.shouldRun && !datanode.shutdownForUpgrade) {
       try {
         peer = peerServer.accept();
 
@@ -147,7 +147,7 @@ class DataXceiverServer implements Runnable {
       } catch (AsynchronousCloseException ace) {
         // another thread closed our listener socket - that's expected during shutdown,
         // but not in other circumstances
-        if (datanode.shouldRun) {
+        if (datanode.shouldRun && !datanode.shutdownForUpgrade) {
           LOG.warn(datanode.getDisplayName() + ":DataXceiverServer: ", ace);
         }
       } catch (IOException ie) {
@@ -170,31 +170,53 @@ class DataXceiverServer implements Runnable {
         datanode.shouldRun = false;
       }
     }
-    synchronized (this) {
-      for (Peer p : peers) {
-        IOUtils.cleanup(LOG, p);
-      }
-    }
+
+    // Close the server to stop reception of more requests.
     try {
       peerServer.close();
+      closed = true;
     } catch (IOException ie) {
       LOG.warn(datanode.getDisplayName()
           + " :DataXceiverServer: close exception", ie);
     }
+
+    // if in restart prep stage, notify peers before closing them.
+    if (datanode.shutdownForUpgrade) {
+      restartNotifyPeers();
+      // Each thread needs some time to process it. If a thread needs
+      // to send an OOB message to the client, but blocked on network for
+      // long time, we need to force its termination.
+      LOG.info("Shutting down DataXceiverServer before restart");
+      // Allow roughly up to 2 seconds.
+      for (int i = 0; getNumPeers() > 0 && i < 10; i++) {
+        try {
+          Thread.sleep(200);
+        } catch (InterruptedException e) {
+          // ignore
+        }
+      }
+    }
+    // Close all peers.
+    closeAllPeers();
   }
 
   void kill() {
-    assert datanode.shouldRun == false :
-      "shoudRun should be set to false before killing";
+    assert (datanode.shouldRun == false || datanode.shutdownForUpgrade) :
+      "shoudRun should be set to false or restarting should be true"
+      + " before killing";
     try {
       this.peerServer.close();
+      this.closed = true;
     } catch (IOException ie) {
       LOG.warn(datanode.getDisplayName() + ":DataXceiverServer.kill(): ", ie);
     }
   }
   
-  synchronized void addPeer(Peer peer) {
-    peers.add(peer);
+  synchronized void addPeer(Peer peer, Thread t) throws IOException {
+    if (closed) {
+      throw new IOException("Server closed.");
+    }
+    peers.put(peer, t);
   }
 
   synchronized void closePeer(Peer peer) {
@@ -202,6 +224,31 @@ class DataXceiverServer implements Runnable {
     IOUtils.cleanup(null, peer);
   }
 
+  // Notify all peers of the shutdown and restart.
+  // datanode.shouldRun should still be true and datanode.restarting should
+  // be set true before calling this method.
+  synchronized void restartNotifyPeers() {
+    assert (datanode.shouldRun == true && datanode.shutdownForUpgrade);
+    for (Peer p : peers.keySet()) {
+      // interrupt each and every DataXceiver thread.
+      peers.get(p).interrupt();
+    }
+  }
+
+  // Close all peers and clear the map.
+  synchronized void closeAllPeers() {
+    LOG.info("Closing all peers.");
+    for (Peer p : peers.keySet()) {
+      IOUtils.cleanup(LOG, p);
+    }
+    peers.clear();
+  }
+
+  // Return the number of peers.
+  synchronized int getNumPeers() {
+    return peers.size();
+  }
+
   synchronized void releasePeer(Peer peer) {
     peers.remove(peer);
   }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/FsDatasetSpi.java

@@ -412,5 +412,22 @@ public interface FsDatasetSpi<V extends FsVolumeSpi> extends FSDatasetMBean {
    */
   public HdfsBlocksMetadata getHdfsBlocksMetadata(String bpid,
       long[] blockIds) throws IOException;
+
+  /**
+   * Enable 'trash' for the given dataset. When trash is enabled, files are
+   * moved to a separate trash directory instead of being deleted immediately.
+   * This can be useful for example during rolling upgrades.
+   */
+  public void enableTrash(String bpid);
+
+  /**
+   * Restore trash
+   */
+  public void restoreTrash(String bpid);
+
+  /**
+   * @return true when trash is enabled
+   */
+  public boolean trashEnabled(String bpid);
 }
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/BlockPoolSlice.java

@@ -21,9 +21,12 @@ import java.io.BufferedInputStream;
 import java.io.DataInputStream;
 import java.io.File;
 import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileWriter;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.RandomAccessFile;
+import java.util.Scanner;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.DU;
@@ -36,11 +39,14 @@ import org.apache.hadoop.hdfs.server.datanode.DataStorage;
 import org.apache.hadoop.hdfs.server.datanode.DatanodeUtil;
 import org.apache.hadoop.hdfs.server.datanode.FinalizedReplica;
 import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo;
+import org.apache.hadoop.hdfs.server.datanode.ReplicaBeingWritten;
 import org.apache.hadoop.hdfs.server.datanode.ReplicaWaitingToBeRecovered;
 import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.util.DataChecksum;
 import org.apache.hadoop.util.DiskChecker;
 import org.apache.hadoop.util.DiskChecker.DiskErrorException;
+import org.apache.hadoop.util.ShutdownHookManager;
+import org.apache.hadoop.util.Time;
 
 /**
  * A block pool slice represents a portion of a block pool stored on a volume.  
@@ -56,6 +62,9 @@ class BlockPoolSlice {
   private final LDir finalizedDir; // directory store Finalized replica
   private final File rbwDir; // directory store RBW replica
   private final File tmpDir; // directory store Temporary replica
+  private static String DU_CACHE_FILE = "dfsUsed";
+  private volatile boolean dfsUsedSaved = false;
+  private static final int SHUTDOWN_HOOK_PRIORITY = 30;
   
   // TODO:FEDERATION scalability issue - a thread per DU is needed
   private final DU dfsUsage;
@@ -106,8 +115,21 @@ class BlockPoolSlice {
         throw new IOException("Mkdirs failed to create " + tmpDir.toString());
       }
     }
-    this.dfsUsage = new DU(bpDir, conf);
+    // Use cached value initially if available. Or the following call will
+    // block until the initial du command completes.
+    this.dfsUsage = new DU(bpDir, conf, loadDfsUsed());
     this.dfsUsage.start();
+
+    // Make the dfs usage to be saved during shutdown.
+    ShutdownHookManager.get().addShutdownHook(
+      new Runnable() {
+        @Override
+        public void run() {
+          if (!dfsUsedSaved) {
+            saveDfsUsed();
+          }
+        }
+      }, SHUTDOWN_HOOK_PRIORITY);
   }
 
   File getDirectory() {
@@ -131,6 +153,79 @@ class BlockPoolSlice {
     return dfsUsage.getUsed();
   }
   
+   /**
+   * Read in the cached DU value and return it if it is less than 600 seconds
+   * old (DU update interval). Slight imprecision of dfsUsed is not critical
+   * and skipping DU can significantly shorten the startup time.
+   * If the cached value is not available or too old, -1 is returned.
+   */
+  long loadDfsUsed() {
+    long cachedDfsUsed;
+    long mtime;
+    Scanner sc;
+
+    try {
+      sc = new Scanner(new File(currentDir, DU_CACHE_FILE));
+    } catch (FileNotFoundException fnfe) {
+      return -1;
+    }
+
+    try {
+      // Get the recorded dfsUsed from the file.
+      if (sc.hasNextLong()) {
+        cachedDfsUsed = sc.nextLong();
+      } else {
+        return -1;
+      }
+      // Get the recorded mtime from the file.
+      if (sc.hasNextLong()) {
+        mtime = sc.nextLong();
+      } else {
+        return -1;
+      }
+
+      // Return the cached value if mtime is okay.
+      if (mtime > 0 && (Time.now() - mtime < 600000L)) {
+        FsDatasetImpl.LOG.info("Cached dfsUsed found for " + currentDir + ": " +
+            cachedDfsUsed);
+        return cachedDfsUsed;
+      }
+      return -1;
+    } finally {
+      sc.close();
+    }
+  }
+
+  /**
+   * Write the current dfsUsed to the cache file.
+   */
+  void saveDfsUsed() {
+    File outFile = new File(currentDir, DU_CACHE_FILE);
+    if (outFile.exists() && !outFile.delete()) {
+      FsDatasetImpl.LOG.warn("Failed to delete old dfsUsed file in " +
+        outFile.getParent());
+    }
+
+    FileWriter out = null;
+    try {
+      long used = getDfsUsed();
+      if (used > 0) {
+        out = new FileWriter(outFile);
+        // mtime is written last, so that truncated writes won't be valid.
+        out.write(Long.toString(used) + " " + Long.toString(Time.now()));
+        out.flush();
+        out.close();
+        out = null;
+      }
+    } catch (IOException ioe) {
+      // If write failed, the volume might be bad. Since the cache file is
+      // not critical, log the error and continue.
+      FsDatasetImpl.LOG.warn("Failed to write dfsUsed to " + outFile, ioe);
+    } finally {
+      IOUtils.cleanup(null, out);
+    }
+  }
+
   /**
    * Temporary files. They get moved to the finalized block directory when
    * the block is finalized.
@@ -191,9 +286,39 @@ class BlockPoolSlice {
         newReplica = new FinalizedReplica(blockId, 
             blockFile.length(), genStamp, volume, blockFile.getParentFile());
       } else {
-        newReplica = new ReplicaWaitingToBeRecovered(blockId,
-            validateIntegrityAndSetLength(blockFile, genStamp), 
-            genStamp, volume, blockFile.getParentFile());
+
+        boolean loadRwr = true;
+        File restartMeta = new File(blockFile.getParent()  +
+            File.pathSeparator + "." + blockFile.getName() + ".restart");
+        Scanner sc = null;
+        try {
+          sc = new Scanner(restartMeta);
+          // The restart meta file exists
+          if (sc.hasNextLong() && (sc.nextLong() > Time.now())) {
+            // It didn't expire. Load the replica as a RBW.
+            newReplica = new ReplicaBeingWritten(blockId,
+                validateIntegrityAndSetLength(blockFile, genStamp), 
+                genStamp, volume, blockFile.getParentFile(), null);
+            loadRwr = false;
+          }
+          sc.close();
+          if (restartMeta.delete()) {
+            FsDatasetImpl.LOG.warn("Failed to delete restart meta file: " +
+              restartMeta.getPath());
+          }
+        } catch (FileNotFoundException fnfe) {
+          // nothing to do here
+        } finally {
+          if (sc != null) {
+            sc.close();
+          }
+        }
+        // Restart meta doesn't exist or expired.
+        if (loadRwr) {
+          newReplica = new ReplicaWaitingToBeRecovered(blockId,
+              validateIntegrityAndSetLength(blockFile, genStamp), 
+              genStamp, volume, blockFile.getParentFile());
+        }
       }
 
       ReplicaInfo oldReplica = volumeMap.add(bpid, newReplica);
@@ -296,6 +421,8 @@ class BlockPoolSlice {
   }
   
   void shutdown() {
+    saveDfsUsed();
+    dfsUsedSaved = true;
     dfsUsage.shutdown();
   }
-}
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetAsyncDiskService.java

@@ -153,29 +153,34 @@ class FsDatasetAsyncDiskService {
    * dfsUsed statistics accordingly.
    */
   void deleteAsync(FsVolumeImpl volume, File blockFile, File metaFile,
-      ExtendedBlock block) {
+      ExtendedBlock block, String trashDirectory) {
     LOG.info("Scheduling " + block.getLocalBlock()
         + " file " + blockFile + " for deletion");
     ReplicaFileDeleteTask deletionTask = new ReplicaFileDeleteTask(
-        volume, blockFile, metaFile, block);
+        volume, blockFile, metaFile, block, trashDirectory);
     execute(volume.getCurrentDir(), deletionTask);
   }
   
   /** A task for deleting a block file and its associated meta file, as well
-   *  as decrement the dfs usage of the volume. 
+   *  as decrement the dfs usage of the volume.
+   *  Optionally accepts a trash directory. If one is specified then the files
+   *  are moved to trash instead of being deleted. If none is specified then the
+   *  files are deleted immediately.
    */
   class ReplicaFileDeleteTask implements Runnable {
     final FsVolumeImpl volume;
     final File blockFile;
     final File metaFile;
     final ExtendedBlock block;
+    final String trashDirectory;
     
     ReplicaFileDeleteTask(FsVolumeImpl volume, File blockFile,
-        File metaFile, ExtendedBlock block) {
+        File metaFile, ExtendedBlock block, String trashDirectory) {
       this.volume = volume;
       this.blockFile = blockFile;
       this.metaFile = metaFile;
       this.block = block;
+      this.trashDirectory = trashDirectory;
     }
 
     @Override
@@ -186,12 +191,39 @@ class FsDatasetAsyncDiskService {
           + " and meta file " + metaFile + " from volume " + volume;
     }
 
+    private boolean deleteFiles() {
+      return blockFile.delete() && (metaFile.delete() || !metaFile.exists());
+    }
+
+    private boolean moveFiles() {
+      File trashDirFile = new File(trashDirectory);
+      if (!trashDirFile.exists() && !trashDirFile.mkdirs()) {
+        LOG.error("Failed to create trash directory " + trashDirectory);
+        return false;
+      }
+
+      if (LOG.isDebugEnabled()) {
+        LOG.debug("Moving files " + blockFile.getName() + " and " +
+            metaFile.getName() + " to trash.");
+      }
+
+      File newBlockFile = new File(trashDirectory, blockFile.getName());
+      File newMetaFile = new File(trashDirectory, metaFile.getName());
+      return (blockFile.renameTo(newBlockFile) &&
+              metaFile.renameTo(newMetaFile));
+    }
+
     @Override
     public void run() {
       long dfsBytes = blockFile.length() + metaFile.length();
-      if (!blockFile.delete() || (!metaFile.delete() && metaFile.exists())) {
-        LOG.warn("Unexpected error trying to delete block "
-            + block.getBlockPoolId() + " " + block.getLocalBlock()
+      boolean result;
+
+      result = (trashDirectory == null) ? deleteFiles() : moveFiles();
+
+      if (!result) {
+        LOG.warn("Unexpected error trying to "
+            + (trashDirectory == null ? "delete" : "move")
+            + " block " + block.getBlockPoolId() + " " + block.getLocalBlock()
             + " at file " + blockFile + ". Ignored.");
       } else {
         if(block.getLocalBlock().getNumBytes() != BlockCommand.NO_ACK){

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java

@@ -17,28 +17,6 @@
  */
 package org.apache.hadoop.hdfs.server.datanode.fsdataset.impl;
 
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.RandomAccessFile;
-import java.nio.ByteBuffer;
-import java.nio.channels.FileChannel;
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.HashMap;
-import java.util.Iterator;
-import java.util.List;
-import java.util.Map;
-import java.util.concurrent.Executor;
-
-import javax.management.NotCompliantMBeanException;
-import javax.management.ObjectName;
-import javax.management.StandardMBean;
-
-import com.google.common.base.Preconditions;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
@@ -46,37 +24,12 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.StorageType;
-import org.apache.hadoop.hdfs.protocol.Block;
-import org.apache.hadoop.hdfs.protocol.BlockListAsLongs;
-import org.apache.hadoop.hdfs.protocol.BlockLocalPathInfo;
-import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
-import org.apache.hadoop.hdfs.protocol.HdfsBlocksMetadata;
-import org.apache.hadoop.hdfs.protocol.RecoveryInProgressException;
+import org.apache.hadoop.hdfs.protocol.*;
 import org.apache.hadoop.hdfs.server.common.GenerationStamp;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.ReplicaState;
 import org.apache.hadoop.hdfs.server.common.Storage;
-import org.apache.hadoop.hdfs.server.datanode.BlockMetadataHeader;
-import org.apache.hadoop.hdfs.server.datanode.DataBlockScanner;
-import org.apache.hadoop.hdfs.server.datanode.DataNode;
-import org.apache.hadoop.hdfs.server.datanode.DataStorage;
-import org.apache.hadoop.hdfs.server.datanode.FinalizedReplica;
-import org.apache.hadoop.hdfs.server.datanode.Replica;
-import org.apache.hadoop.hdfs.server.datanode.ReplicaAlreadyExistsException;
-import org.apache.hadoop.hdfs.server.datanode.ReplicaBeingWritten;
-import org.apache.hadoop.hdfs.server.datanode.ReplicaInPipeline;
-import org.apache.hadoop.hdfs.server.datanode.ReplicaInfo;
-import org.apache.hadoop.hdfs.server.datanode.ReplicaNotFoundException;
-import org.apache.hadoop.hdfs.server.datanode.ReplicaUnderRecovery;
-import org.apache.hadoop.hdfs.server.datanode.ReplicaWaitingToBeRecovered;
-import org.apache.hadoop.hdfs.server.datanode.StorageLocation;
-import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsDatasetSpi;
-import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsVolumeSpi;
-import org.apache.hadoop.hdfs.server.datanode.fsdataset.LengthInputStream;
-import org.apache.hadoop.hdfs.server.datanode.fsdataset.ReplicaInputStreams;
-import org.apache.hadoop.hdfs.server.datanode.fsdataset.ReplicaOutputStreams;
-import org.apache.hadoop.hdfs.server.datanode.fsdataset.RollingLogs;
-import org.apache.hadoop.hdfs.server.datanode.fsdataset.RoundRobinVolumeChoosingPolicy;
-import org.apache.hadoop.hdfs.server.datanode.fsdataset.VolumeChoosingPolicy;
+import org.apache.hadoop.hdfs.server.datanode.*;
+import org.apache.hadoop.hdfs.server.datanode.fsdataset.*;
 import org.apache.hadoop.hdfs.server.datanode.metrics.FSDatasetMBean;
 import org.apache.hadoop.hdfs.server.protocol.BlockRecoveryCommand.RecoveringBlock;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeStorage;
@@ -90,6 +43,15 @@ import org.apache.hadoop.util.DiskChecker.DiskOutOfSpaceException;
 import org.apache.hadoop.util.ReflectionUtils;
 import org.apache.hadoop.util.Time;
 
+import javax.management.NotCompliantMBeanException;
+import javax.management.ObjectName;
+import javax.management.StandardMBean;
+import java.io.*;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.util.*;
+import java.util.concurrent.Executor;
+
 /**************************************************
  * FSDataset manages a set of data blocks.  Each block
  * has a unique name and an extent on disk.
@@ -193,6 +155,7 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
   }
     
   final DataNode datanode;
+  final DataStorage dataStorage;
   final FsVolumeList volumes;
   final FsDatasetAsyncDiskService asyncDiskService;
   final FsDatasetCache cacheManager;
@@ -209,6 +172,7 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
   FsDatasetImpl(DataNode datanode, DataStorage storage, Configuration conf
       ) throws IOException {
     this.datanode = datanode;
+    this.dataStorage = storage;
     // The number of volumes required for operation is the total number 
     // of volumes minus the number of failed volumes we can tolerate.
     final int volFailuresTolerated =
@@ -1234,7 +1198,8 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
       // finishes.
       asyncDiskService.deleteAsync(v, f,
           FsDatasetUtil.getMetaFile(f, invalidBlks[i].getGenerationStamp()),
-          new ExtendedBlock(bpid, invalidBlks[i]));
+          new ExtendedBlock(bpid, invalidBlks[i]),
+          dataStorage.getTrashDirectoryForBlockFile(bpid, f));
     }
     if (error) {
       throw new IOException("Error in deleting blocks.");
@@ -1762,11 +1727,13 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
   }
   
   @Override
-  public synchronized void addBlockPool(String bpid, Configuration conf)
+  public void addBlockPool(String bpid, Configuration conf)
       throws IOException {
     LOG.info("Adding block pool " + bpid);
-    volumes.addBlockPool(bpid, conf);
-    volumeMap.initBlockPool(bpid);
+    synchronized(this) {
+      volumes.addBlockPool(bpid, conf);
+      volumeMap.initBlockPool(bpid);
+    }
     volumes.getAllVolumesMap(bpid, volumeMap);
   }
 
@@ -1895,6 +1862,21 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
         blocksVolumeIds, blocksVolumeIndexes);
   }
 
+  @Override
+  public void enableTrash(String bpid) {
+    dataStorage.enableTrash(bpid);
+  }
+
+  @Override
+  public void restoreTrash(String bpid) {
+    dataStorage.restoreTrash(bpid);
+  }
+
+  @Override
+  public boolean trashEnabled(String bpid) {
+    return dataStorage.trashEnabled(bpid);
+  }
+
   @Override
   public RollingLogs createRollingLogs(String bpid, String prefix
       ) throws IOException {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsVolumeList.java

@@ -96,10 +96,41 @@ class FsVolumeList {
     }
   }
   
-  void getAllVolumesMap(String bpid, ReplicaMap volumeMap) throws IOException {
+  void getAllVolumesMap(final String bpid, final ReplicaMap volumeMap) throws IOException {
     long totalStartTime = System.currentTimeMillis();
-    for (FsVolumeImpl v : volumes) {
-      getVolumeMap(bpid, v, volumeMap);
+    final List<IOException> exceptions = Collections.synchronizedList(
+        new ArrayList<IOException>());
+    List<Thread> replicaAddingThreads = new ArrayList<Thread>();
+    for (final FsVolumeImpl v : volumes) {
+      Thread t = new Thread() {
+        public void run() {
+          try {
+            FsDatasetImpl.LOG.info("Adding replicas to map for block pool " +
+                bpid + " on volume " + v + "...");
+            long startTime = System.currentTimeMillis();
+            v.getVolumeMap(bpid, volumeMap);
+            long timeTaken = System.currentTimeMillis() - startTime;
+            FsDatasetImpl.LOG.info("Time to add replicas to map for block pool"
+                + " " + bpid + " on volume " + v + ": " + timeTaken + "ms");
+          } catch (IOException ioe) {
+            FsDatasetImpl.LOG.info("Caught exception while adding replicas " +
+                "from " + v + ". Will throw later.", ioe);
+            exceptions.add(ioe);
+          }
+        }
+      };
+      replicaAddingThreads.add(t);
+      t.start();
+    }
+    for (Thread t : replicaAddingThreads) {
+      try {
+        t.join();
+      } catch (InterruptedException ie) {
+        throw new IOException(ie);
+      }
+    }
+    if (!exceptions.isEmpty()) {
+      throw exceptions.get(0);
     }
     long totalTimeTaken = System.currentTimeMillis() - totalStartTime;
     FsDatasetImpl.LOG.info("Total time to add all replicas to map: "
@@ -219,4 +250,4 @@ class FsVolumeList {
       }
     }
   }
-}
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/BackupImage.java

@@ -208,7 +208,7 @@ public class BackupImage extends FSImage {
       backupInputStream.setBytes(data, logVersion);
 
       long numTxnsAdvanced = logLoader.loadEditRecords(
-          backupInputStream, true, lastAppliedTxId + 1, null);
+          backupInputStream, true, lastAppliedTxId + 1, null, null);
       if (numTxnsAdvanced != numTxns) {
         throw new IOException("Batch of txns starting at txnid " +
             firstTxId + " was supposed to contain " + numTxns +
@@ -266,7 +266,7 @@ public class BackupImage extends FSImage {
           editStreams.add(s);
         }
       }
-      loadEdits(editStreams, namesystem, null);
+      loadEdits(editStreams, namesystem);
     }
     
     // now, need to load the in-progress file
@@ -302,7 +302,7 @@ public class BackupImage extends FSImage {
         
         FSEditLogLoader loader =
             new FSEditLogLoader(namesystem, lastAppliedTxId);
-        loader.loadFSEdits(stream, lastAppliedTxId + 1, null);
+        loader.loadFSEdits(stream, lastAppliedTxId + 1);
         lastAppliedTxId = loader.getLastAppliedTxId();
         assert lastAppliedTxId == getEditLog().getLastWrittenTxId();
       } finally {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/BackupJournalManager.java

@@ -126,6 +126,11 @@ class BackupJournalManager implements JournalManager {
     throw new UnsupportedOperationException();
   }
 
+  @Override
+  public void discardSegments(long startTxId) throws IOException {
+    throw new UnsupportedOperationException();
+  }
+
   @Override
   public long getJournalCTime() throws IOException {
     throw new UnsupportedOperationException();

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/BackupNode.java

@@ -413,9 +413,9 @@ public class BackupNode extends NameNode {
       LOG.fatal(errorMsg);
       throw new IOException(errorMsg);
     }
-    assert HdfsConstants.LAYOUT_VERSION == nsInfo.getLayoutVersion() :
+    assert HdfsConstants.NAMENODE_LAYOUT_VERSION == nsInfo.getLayoutVersion() :
       "Active and backup node layout versions must be the same. Expected: "
-      + HdfsConstants.LAYOUT_VERSION + " actual "+ nsInfo.getLayoutVersion();
+      + HdfsConstants.NAMENODE_LAYOUT_VERSION + " actual "+ nsInfo.getLayoutVersion();
     return nsInfo;
   }
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/CheckpointSignature.java

@@ -21,6 +21,7 @@ import java.io.IOException;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.hdfs.server.common.StorageInfo;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NodeType;
 import org.apache.hadoop.hdfs.server.namenode.FSImage;
 
 import com.google.common.collect.ComparisonChain;
@@ -47,6 +48,7 @@ public class CheckpointSignature extends StorageInfo
   }
 
   CheckpointSignature(String str) {
+    super(NodeType.NAME_NODE);
     String[] fields = str.split(FIELD_SEPARATOR);
     assert fields.length == NUM_FIELDS :
       "Must be " + NUM_FIELDS + " fields in CheckpointSignature";

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/Checkpointer.java

@@ -33,6 +33,7 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hdfs.DFSUtil;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NamenodeRole;
+import org.apache.hadoop.hdfs.server.namenode.NNStorage.NameNodeFile;
 import org.apache.hadoop.hdfs.server.protocol.CheckpointCommand;
 import org.apache.hadoop.hdfs.server.protocol.NamenodeCommand;
 import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocol;
@@ -220,9 +221,9 @@ class Checkpointer extends Daemon {
         LOG.info("Unable to roll forward using only logs. Downloading " +
             "image with txid " + sig.mostRecentCheckpointTxId);
         MD5Hash downloadedHash = TransferFsImage.downloadImageToStorage(
-            backupNode.nnHttpAddress, sig.mostRecentCheckpointTxId,
-            bnStorage, true);
-        bnImage.saveDigestAndRenameCheckpointImage(
+            backupNode.nnHttpAddress, sig.mostRecentCheckpointTxId, bnStorage,
+            true);
+        bnImage.saveDigestAndRenameCheckpointImage(NameNodeFile.IMAGE,
             sig.mostRecentCheckpointTxId, downloadedHash);
         lastApplied = sig.mostRecentCheckpointTxId;
         needReloadImage = true;
@@ -240,7 +241,8 @@ class Checkpointer extends Daemon {
 
       if(needReloadImage) {
         LOG.info("Loading image with txid " + sig.mostRecentCheckpointTxId);
-        File file = bnStorage.findImageFile(sig.mostRecentCheckpointTxId);
+        File file = bnStorage.findImageFile(NameNodeFile.IMAGE,
+            sig.mostRecentCheckpointTxId);
         bnImage.reloadFromImageFile(file, backupNode.getNamesystem());
       }
       rollForwardByApplyingLogs(manifest, bnImage, backupNode.getNamesystem());
@@ -263,7 +265,7 @@ class Checkpointer extends Daemon {
     if(cpCmd.needToReturnImage()) {
       TransferFsImage.uploadImageFromStorage(
           backupNode.nnHttpAddress, getImageListenAddress(),
-          bnStorage, txid);
+          bnStorage, NameNodeFile.IMAGE, txid);
     }
 
     getRemoteNamenodeProxy().endCheckpoint(backupNode.getRegistration(), sig);
@@ -307,6 +309,6 @@ class Checkpointer extends Daemon {
     }
     LOG.info("Checkpointer about to load edits from " +
         editsStreams.size() + " stream(s).");
-    dstImage.loadEdits(editsStreams, dstNamesystem, null);
+    dstImage.loadEdits(editsStreams, dstNamesystem);
   }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/EditLogFileInputStream.java

@@ -36,7 +36,6 @@ import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LayoutFlags;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
-import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
 import org.apache.hadoop.hdfs.server.common.Storage;
 import org.apache.hadoop.hdfs.server.namenode.TransferFsImage.HttpGetFailedException;
 import org.apache.hadoop.hdfs.web.URLConnectionFactory;
@@ -149,7 +148,8 @@ public class EditLogFileInputStream extends EditLogInputStream {
       } catch (EOFException eofe) {
         throw new LogHeaderCorruptException("No header found in log");
       }
-      if (LayoutVersion.supports(Feature.ADD_LAYOUT_FLAGS, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.ADD_LAYOUT_FLAGS, logVersion)) {
         try {
           LayoutFlags.read(dataIn);
         } catch (EOFException eofe) {
@@ -328,12 +328,12 @@ public class EditLogFileInputStream extends EditLogInputStream {
       throw new LogHeaderCorruptException(
           "Reached EOF when reading log header");
     }
-    if (logVersion < HdfsConstants.LAYOUT_VERSION || // future version
+    if (logVersion < HdfsConstants.NAMENODE_LAYOUT_VERSION || // future version
         logVersion > Storage.LAST_UPGRADABLE_LAYOUT_VERSION) { // unsupported
       throw new LogHeaderCorruptException(
           "Unexpected version of the file system log file: "
           + logVersion + ". Current version = "
-          + HdfsConstants.LAYOUT_VERSION + ".");
+          + HdfsConstants.NAMENODE_LAYOUT_VERSION + ".");
     }
     return logVersion;
   }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/EditLogFileOutputStream.java

@@ -132,7 +132,7 @@ public class EditLogFileOutputStream extends EditLogOutputStream {
    */
   @VisibleForTesting
   public static void writeHeader(DataOutputStream out) throws IOException {
-    out.writeInt(HdfsConstants.LAYOUT_VERSION);
+    out.writeInt(HdfsConstants.NAMENODE_LAYOUT_VERSION);
     LayoutFlags.write(out);
   }
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLog.java

@@ -84,6 +84,7 @@ import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.SymlinkOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.TimesOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.UpdateBlocksOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.UpdateMasterKeyOp;
+import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RollingUpgradeOp;
 import org.apache.hadoop.hdfs.server.namenode.JournalSet.JournalAndStream;
 import org.apache.hadoop.hdfs.server.namenode.metrics.NameNodeMetrics;
 import org.apache.hadoop.hdfs.server.protocol.NamenodeRegistration;
@@ -1031,6 +1032,18 @@ public class FSEditLog implements LogsPurgeable {
     logEdit(op);
   }
 
+  void logStartRollingUpgrade(long startTime) {
+    RollingUpgradeOp op = RollingUpgradeOp.getStartInstance(cache.get());
+    op.setTime(startTime);
+    logEdit(op);
+  }
+
+  void logFinalizeRollingUpgrade(long finalizeTime) {
+    RollingUpgradeOp op = RollingUpgradeOp.getFinalizeInstance(cache.get());
+    op.setTime(finalizeTime);
+    logEdit(op);
+  }
+
   void logSetAcl(String src, List<AclEntry> entries) {
     SetAclOp op = SetAclOp.getInstance();
     op.src = src;
@@ -1415,7 +1428,14 @@ public class FSEditLog implements LogsPurgeable {
       }
     }
   }
-  
+
+  public synchronized void discardSegments(long markerTxid)
+      throws IOException {
+    for (JournalAndStream jas : journalSet.getAllJournalStreams()) {
+      jas.getManager().discardSegments(markerTxid);
+    }
+  }
+
   @Override
   public void selectInputStreams(Collection<EditLogInputStream> streams,
       long fromTxId, boolean inProgressOk) throws IOException {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogLoader.java

@@ -36,10 +36,11 @@ import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
-import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.server.blockmanagement.BlockInfo;
 import org.apache.hadoop.hdfs.server.blockmanagement.BlockInfoUnderConstruction;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.RollingUpgradeStartupOption;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
 import org.apache.hadoop.hdfs.server.common.Storage;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.AddBlockOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.AddCacheDirectiveInfoOp;
@@ -66,6 +67,7 @@ import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RenameOldOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RenameOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RenameSnapshotOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RenewDelegationTokenOp;
+import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RollingUpgradeOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.SetAclOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.SetGenstampV1Op;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.SetGenstampV2Op;
@@ -80,6 +82,7 @@ import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.UpdateBlocksOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.UpdateMasterKeyOp;
 import org.apache.hadoop.hdfs.server.namenode.INode.BlocksMapUpdateInfo;
 import org.apache.hadoop.hdfs.server.namenode.LeaseManager.Lease;
+import org.apache.hadoop.hdfs.server.namenode.NNStorage.NameNodeFile;
 import org.apache.hadoop.hdfs.server.namenode.snapshot.Snapshot;
 import org.apache.hadoop.hdfs.server.namenode.startupprogress.Phase;
 import org.apache.hadoop.hdfs.server.namenode.startupprogress.StartupProgress;
@@ -95,22 +98,30 @@ import com.google.common.base.Preconditions;
 @InterfaceStability.Evolving
 public class FSEditLogLoader {
   static final Log LOG = LogFactory.getLog(FSEditLogLoader.class.getName());
-  static long REPLAY_TRANSACTION_LOG_INTERVAL = 1000; // 1sec
+  static final long REPLAY_TRANSACTION_LOG_INTERVAL = 1000; // 1sec
+
   private final FSNamesystem fsNamesys;
   private long lastAppliedTxId;
+  /** Total number of end transactions loaded. */
+  private int totalEdits = 0;
   
   public FSEditLogLoader(FSNamesystem fsNamesys, long lastAppliedTxId) {
     this.fsNamesys = fsNamesys;
     this.lastAppliedTxId = lastAppliedTxId;
   }
   
+  long loadFSEdits(EditLogInputStream edits, long expectedStartingTxId)
+      throws IOException {
+    return loadFSEdits(edits, expectedStartingTxId, null, null);
+  }
+
   /**
    * Load an edit log, and apply the changes to the in-memory structure
    * This is where we apply edits that we've been writing to disk all
    * along.
    */
   long loadFSEdits(EditLogInputStream edits, long expectedStartingTxId,
-      MetaRecoveryContext recovery) throws IOException {
+      StartupOption startOpt, MetaRecoveryContext recovery) throws IOException {
     StartupProgress prog = NameNode.getStartupProgress();
     Step step = createStartupProgressStep(edits);
     prog.beginStep(Phase.LOADING_EDITS, step);
@@ -118,8 +129,8 @@ public class FSEditLogLoader {
     try {
       long startTime = now();
       FSImage.LOG.info("Start loading edits file " + edits.getName());
-      long numEdits = loadEditRecords(edits, false, 
-                                 expectedStartingTxId, recovery);
+      long numEdits = loadEditRecords(edits, false, expectedStartingTxId,
+          startOpt, recovery);
       FSImage.LOG.info("Edits file " + edits.getName() 
           + " of size " + edits.length() + " edits # " + numEdits 
           + " loaded in " + (now()-startTime)/1000 + " seconds");
@@ -132,8 +143,8 @@ public class FSEditLogLoader {
   }
 
   long loadEditRecords(EditLogInputStream in, boolean closeOnExit,
-                      long expectedStartingTxId, MetaRecoveryContext recovery)
-      throws IOException {
+      long expectedStartingTxId, StartupOption startOpt,
+      MetaRecoveryContext recovery) throws IOException {
     FSDirectory fsDir = fsNamesys.dir;
 
     EnumMap<FSEditLogOpCodes, Holder<Integer>> opCounts =
@@ -205,12 +216,23 @@ public class FSEditLogLoader {
             }
           }
           try {
-            long inodeId = applyEditLogOp(op, fsDir, in.getVersion(), lastInodeId);
+            if (LOG.isTraceEnabled()) {
+              LOG.trace("op=" + op + ", startOpt=" + startOpt
+                  + ", numEdits=" + numEdits + ", totalEdits=" + totalEdits);
+            }
+            long inodeId = applyEditLogOp(op, fsDir, startOpt,
+                in.getVersion(), lastInodeId);
             if (lastInodeId < inodeId) {
               lastInodeId = inodeId;
             }
+          } catch (RollingUpgradeOp.RollbackException e) {
+            throw e;
           } catch (Throwable e) {
             LOG.error("Encountered exception on operation " + op, e);
+            if (recovery == null) {
+              throw e instanceof IOException? (IOException)e: new IOException(e);
+            }
+
             MetaRecoveryContext.editLogLoaderPrompt("Failed to " +
              "apply edit log operation " + op + ": error " +
              e.getMessage(), recovery, "applying edits");
@@ -236,6 +258,10 @@ public class FSEditLogLoader {
             }
           }
           numEdits++;
+          totalEdits++;
+        } catch (RollingUpgradeOp.RollbackException e) {
+          LOG.info("Stopped at OP_START_ROLLING_UPGRADE for rollback.");
+          break;
         } catch (MetaRecoveryContext.RequestStopException e) {
           MetaRecoveryContext.LOG.warn("Stopped reading edit log at " +
               in.getPosition() + "/"  + in.length());
@@ -267,7 +293,8 @@ public class FSEditLogLoader {
     long inodeId = inodeIdFromOp;
 
     if (inodeId == INodeId.GRANDFATHER_INODE_ID) {
-      if (LayoutVersion.supports(Feature.ADD_INODE_ID, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.ADD_INODE_ID, logVersion)) {
         throw new IOException("The layout version " + logVersion
             + " supports inodeId but gave bogus inodeId");
       }
@@ -284,7 +311,7 @@ public class FSEditLogLoader {
 
   @SuppressWarnings("deprecation")
   private long applyEditLogOp(FSEditLogOp op, FSDirectory fsDir,
-      int logVersion, long lastInodeId) throws IOException {
+      StartupOption startOpt, int logVersion, long lastInodeId) throws IOException {
     long inodeId = INodeId.GRANDFATHER_INODE_ID;
     if (LOG.isTraceEnabled()) {
       LOG.trace("replaying edit log: " + op);
@@ -689,6 +716,30 @@ public class FSEditLogLoader {
       fsNamesys.setLastAllocatedBlockId(allocateBlockIdOp.blockId);
       break;
     }
+    case OP_ROLLING_UPGRADE_START: {
+      if (startOpt == StartupOption.ROLLINGUPGRADE) {
+        final RollingUpgradeStartupOption rollingUpgradeOpt
+            = startOpt.getRollingUpgradeStartupOption(); 
+        if (rollingUpgradeOpt == RollingUpgradeStartupOption.ROLLBACK) {
+          throw new RollingUpgradeOp.RollbackException();
+        } else if (rollingUpgradeOpt == RollingUpgradeStartupOption.DOWNGRADE) {
+          //ignore upgrade marker
+          break;
+        }
+      }
+      // start rolling upgrade
+      final long startTime = ((RollingUpgradeOp) op).getTime();
+      fsNamesys.startRollingUpgradeInternal(startTime);
+      fsNamesys.triggerRollbackCheckpoint();
+      break;
+    }
+    case OP_ROLLING_UPGRADE_FINALIZE: {
+      final long finalizeTime = ((RollingUpgradeOp) op).getTime();
+      fsNamesys.finalizeRollingUpgradeInternal(finalizeTime);
+      fsNamesys.getFSImage().renameCheckpoint(NameNodeFile.IMAGE_ROLLBACK,
+          NameNodeFile.IMAGE);
+      break;
+    }
     case OP_ADD_CACHE_DIRECTIVE: {
       AddCacheDirectiveInfoOp addOp = (AddCacheDirectiveInfoOp) op;
       CacheDirectiveInfo result = fsNamesys.
@@ -927,7 +978,7 @@ public class FSEditLogLoader {
     // The editlog must be emptied by restarting the namenode, before proceeding
     // with the upgrade.
     if (Storage.is203LayoutVersion(logVersion)
-        && logVersion != HdfsConstants.LAYOUT_VERSION) {
+        && logVersion != HdfsConstants.NAMENODE_LAYOUT_VERSION) {
       String msg = "During upgrade failed to load the editlog version "
           + logVersion + " from release 0.20.203. Please go back to the old "
           + " release and restart the namenode. This empties the editlog "

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogOp.java

@@ -44,6 +44,8 @@ import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_RENAME;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_RENAME_OLD;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_RENAME_SNAPSHOT;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_RENEW_DELEGATION_TOKEN;
+import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_ROLLING_UPGRADE_FINALIZE;
+import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_ROLLING_UPGRADE_START;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_SET_ACL;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_SET_GENSTAMP_V1;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_SET_GENSTAMP_V2;
@@ -176,8 +178,13 @@ public abstract class FSEditLogOp {
       inst.put(OP_ADD_CACHE_POOL, new AddCachePoolOp());
       inst.put(OP_MODIFY_CACHE_POOL, new ModifyCachePoolOp());
       inst.put(OP_REMOVE_CACHE_POOL, new RemoveCachePoolOp());
+
       inst.put(OP_ADD_BLOCK, new AddBlockOp());
       inst.put(OP_SET_ACL, new SetAclOp());
+      inst.put(OP_ROLLING_UPGRADE_START, new RollingUpgradeOp(
+          OP_ROLLING_UPGRADE_START, "start"));
+      inst.put(OP_ROLLING_UPGRADE_FINALIZE, new RollingUpgradeOp(
+          OP_ROLLING_UPGRADE_FINALIZE, "finalize"));
     }
     
     public FSEditLogOp get(FSEditLogOpCodes opcode) {
@@ -265,8 +272,8 @@ public abstract class FSEditLogOp {
   
   void readRpcIds(DataInputStream in, int logVersion)
       throws IOException {
-    if (LayoutVersion.supports(Feature.EDITLOG_SUPPORT_RETRYCACHE,
-        logVersion)) {
+    if (NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.EDITLOG_SUPPORT_RETRYCACHE, logVersion)) {
       this.rpcClientId = FSImageSerialization.readBytes(in);
       this.rpcCallId = FSImageSerialization.readInt(in);
     }
@@ -313,7 +320,7 @@ public abstract class FSEditLogOp {
 
     private static List<AclEntry> read(DataInputStream in, int logVersion)
         throws IOException {
-      if (!LayoutVersion.supports(Feature.EXTENDED_ACL, logVersion)) {
+      if (!NameNodeLayoutVersion.supports(Feature.EXTENDED_ACL, logVersion)) {
         return null;
       }
 
@@ -478,18 +485,20 @@ public abstract class FSEditLogOp {
     @Override
     void readFields(DataInputStream in, int logVersion)
         throws IOException {
-      if (!LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.length = in.readInt();
       }
-      if (LayoutVersion.supports(Feature.ADD_INODE_ID, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.ADD_INODE_ID, logVersion)) {
         this.inodeId = in.readLong();
       } else {
         // The inodeId should be updated when this editLogOp is applied
         this.inodeId = INodeId.GRANDFATHER_INODE_ID;
       }
       if ((-17 < logVersion && length != 4) ||
-          (logVersion <= -17 && length != 5 && !LayoutVersion.supports(
-              Feature.EDITLOG_OP_OPTIMIZATION, logVersion))) {
+          (logVersion <= -17 && length != 5 && !NameNodeLayoutVersion.supports(
+              LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion))) {
         throw new IOException("Incorrect data format."  +
                               " logVersion is " + logVersion +
                               " but writables.length is " +
@@ -497,7 +506,8 @@ public abstract class FSEditLogOp {
       }
       this.path = FSImageSerialization.readString(in);
 
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.replication = FSImageSerialization.readShort(in);
         this.mtime = FSImageSerialization.readLong(in);
       } else {
@@ -505,8 +515,10 @@ public abstract class FSEditLogOp {
         this.mtime = readLong(in);
       }
 
-      if (LayoutVersion.supports(Feature.FILE_ACCESS_TIME, logVersion)) {
-        if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.FILE_ACCESS_TIME, logVersion)) {
+        if (NameNodeLayoutVersion.supports(
+            LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
           this.atime = FSImageSerialization.readLong(in);
         } else {
           this.atime = readLong(in);
@@ -515,7 +527,8 @@ public abstract class FSEditLogOp {
         this.atime = 0;
       }
 
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.blockSize = FSImageSerialization.readLong(in);
       } else {
         this.blockSize = readLong(in);
@@ -931,7 +944,8 @@ public abstract class FSEditLogOp {
     void readFields(DataInputStream in, int logVersion)
         throws IOException {
       this.path = FSImageSerialization.readString(in);
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.replication = FSImageSerialization.readShort(in);
       } else {
         this.replication = readShort(in);
@@ -1022,7 +1036,8 @@ public abstract class FSEditLogOp {
     @Override
     void readFields(DataInputStream in, int logVersion)
         throws IOException {
-      if (!LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.length = in.readInt();
         if (length < 3) { // trg, srcs.., timestamp
           throw new IOException("Incorrect data format " +
@@ -1031,7 +1046,8 @@ public abstract class FSEditLogOp {
       }
       this.trg = FSImageSerialization.readString(in);
       int srcSize = 0;
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         srcSize = in.readInt();
       } else {
         srcSize = this.length - 1 - 1; // trg and timestamp
@@ -1050,7 +1066,8 @@ public abstract class FSEditLogOp {
         srcs[i]= FSImageSerialization.readString(in);
       }
       
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.timestamp = FSImageSerialization.readLong(in);
       } else {
         this.timestamp = readLong(in);
@@ -1156,7 +1173,8 @@ public abstract class FSEditLogOp {
     @Override
     void readFields(DataInputStream in, int logVersion)
         throws IOException {
-      if (!LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.length = in.readInt();
         if (this.length != 3) {
           throw new IOException("Incorrect data format. "
@@ -1165,7 +1183,8 @@ public abstract class FSEditLogOp {
       }
       this.src = FSImageSerialization.readString(in);
       this.dst = FSImageSerialization.readString(in);
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.timestamp = FSImageSerialization.readLong(in);
       } else {
         this.timestamp = readLong(in);
@@ -1252,14 +1271,16 @@ public abstract class FSEditLogOp {
     @Override
     void readFields(DataInputStream in, int logVersion)
         throws IOException {
-      if (!LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.length = in.readInt();
         if (this.length != 2) {
           throw new IOException("Incorrect data format. " + "delete operation.");
         }
       }
       this.path = FSImageSerialization.readString(in);
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.timestamp = FSImageSerialization.readLong(in);
       } else {
         this.timestamp = readLong(in);
@@ -1360,22 +1381,26 @@ public abstract class FSEditLogOp {
     
     @Override
     void readFields(DataInputStream in, int logVersion) throws IOException {
-      if (!LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.length = in.readInt();
       }
       if (-17 < logVersion && length != 2 ||
           logVersion <= -17 && length != 3
-          && !LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+          && !NameNodeLayoutVersion.supports(
+              LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         throw new IOException("Incorrect data format. Mkdir operation.");
       }
-      if (LayoutVersion.supports(Feature.ADD_INODE_ID, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.ADD_INODE_ID, logVersion)) {
         this.inodeId = FSImageSerialization.readLong(in);
       } else {
         // This id should be updated when this editLogOp is applied
         this.inodeId = INodeId.GRANDFATHER_INODE_ID;
       }
       this.path = FSImageSerialization.readString(in);
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.timestamp = FSImageSerialization.readLong(in);
       } else {
         this.timestamp = readLong(in);
@@ -1384,8 +1409,10 @@ public abstract class FSEditLogOp {
       // The disk format stores atimes for directories as well.
       // However, currently this is not being updated/used because of
       // performance reasons.
-      if (LayoutVersion.supports(Feature.FILE_ACCESS_TIME, logVersion)) {
-        if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.FILE_ACCESS_TIME, logVersion)) {
+        if (NameNodeLayoutVersion.supports(
+            LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
           FSImageSerialization.readLong(in);
         } else {
           readLong(in);
@@ -1975,7 +2002,8 @@ public abstract class FSEditLogOp {
     @Override
     void readFields(DataInputStream in, int logVersion)
         throws IOException {
-      if (!LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.length = in.readInt();
         if (length != 3) {
           throw new IOException("Incorrect data format. " + "times operation.");
@@ -1983,7 +2011,8 @@ public abstract class FSEditLogOp {
       }
       this.path = FSImageSerialization.readString(in);
 
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.mtime = FSImageSerialization.readLong(in);
         this.atime = FSImageSerialization.readLong(in);
       } else {
@@ -2092,14 +2121,16 @@ public abstract class FSEditLogOp {
     @Override
     void readFields(DataInputStream in, int logVersion)
         throws IOException {
-      if (!LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.length = in.readInt();
         if (this.length != 4) {
           throw new IOException("Incorrect data format. "
               + "symlink operation.");
         }
       }
-      if (LayoutVersion.supports(Feature.ADD_INODE_ID, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.ADD_INODE_ID, logVersion)) {
         this.inodeId = FSImageSerialization.readLong(in);
       } else {
         // This id should be updated when the editLogOp is applied
@@ -2108,7 +2139,8 @@ public abstract class FSEditLogOp {
       this.path = FSImageSerialization.readString(in);
       this.value = FSImageSerialization.readString(in);
 
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.mtime = FSImageSerialization.readLong(in);
         this.atime = FSImageSerialization.readLong(in);
       } else {
@@ -2226,7 +2258,8 @@ public abstract class FSEditLogOp {
     @Override
     void readFields(DataInputStream in, int logVersion)
         throws IOException {
-      if (!LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.length = in.readInt();
         if (this.length != 3) {
           throw new IOException("Incorrect data format. " + "Rename operation.");
@@ -2235,7 +2268,8 @@ public abstract class FSEditLogOp {
       this.src = FSImageSerialization.readString(in);
       this.dst = FSImageSerialization.readString(in);
 
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.timestamp = FSImageSerialization.readLong(in);
       } else {
         this.timestamp = readLong(in);
@@ -2446,7 +2480,8 @@ public abstract class FSEditLogOp {
         throws IOException {
       this.token = new DelegationTokenIdentifier();
       this.token.readFields(in);
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.expiryTime = FSImageSerialization.readLong(in);
       } else {
         this.expiryTime = readLong(in);
@@ -2518,7 +2553,8 @@ public abstract class FSEditLogOp {
         throws IOException {
       this.token = new DelegationTokenIdentifier();
       this.token.readFields(in);
-      if (LayoutVersion.supports(Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITLOG_OP_OPTIMIZATION, logVersion)) {
         this.expiryTime = FSImageSerialization.readLong(in);
       } else {
         this.expiryTime = readLong(in);
@@ -3542,6 +3578,65 @@ public abstract class FSEditLogOp {
       this.len = in.readLong();
     }
   }
+  /**
+   * Operation corresponding to upgrade
+   */
+  static class RollingUpgradeOp extends FSEditLogOp { // @Idempotent
+    private final String name;
+    private long time;
+
+    public RollingUpgradeOp(FSEditLogOpCodes code, String name) {
+      super(code);
+      this.name = name.toUpperCase();
+    }
+
+    static RollingUpgradeOp getStartInstance(OpInstanceCache cache) {
+      return (RollingUpgradeOp) cache.get(OP_ROLLING_UPGRADE_START);
+    }
+
+    static RollingUpgradeOp getFinalizeInstance(OpInstanceCache cache) {
+      return (RollingUpgradeOp) cache.get(OP_ROLLING_UPGRADE_FINALIZE);
+    }
+
+    long getTime() {
+      return time;
+    }
+
+    void setTime(long time) {
+      this.time = time;
+    }
+
+    @Override
+    void readFields(DataInputStream in, int logVersion) throws IOException {
+      time = in.readLong();
+    }
+
+    @Override
+    public void writeFields(DataOutputStream out) throws IOException {
+      FSImageSerialization.writeLong(time, out);
+    }
+
+    @Override
+    protected void toXml(ContentHandler contentHandler) throws SAXException {
+      XMLUtils.addSaxString(contentHandler, name + "TIME",
+          Long.valueOf(time).toString());
+    }
+
+    @Override
+    void fromXml(Stanza st) throws InvalidXmlException {
+      this.time = Long.valueOf(st.getValue(name + "TIME"));
+    }
+
+    @Override
+    public String toString() {
+      return new StringBuilder().append("RollingUpgradeOp [").append(name)
+          .append(", time=").append(time).append("]").toString();
+    }
+    
+    static class RollbackException extends IOException {
+      private static final long serialVersionUID = 1L;
+    }
+  }
 
   /**
    * Class for writing editlog ops
@@ -3592,7 +3687,8 @@ public abstract class FSEditLogOp {
      */
     public Reader(DataInputStream in, StreamLimiter limiter, int logVersion) {
       this.logVersion = logVersion;
-      if (LayoutVersion.supports(Feature.EDITS_CHESKUM, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.EDITS_CHESKUM, logVersion)) {
         this.checksum = new PureJavaCrc32();
       } else {
         this.checksum = null;
@@ -3731,7 +3827,8 @@ public abstract class FSEditLogOp {
         throw new IOException("Read invalid opcode " + opCode);
       }
 
-      if (LayoutVersion.supports(Feature.STORED_TXIDS, logVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.STORED_TXIDS, logVersion)) {
         // Read the txid
         op.setTransactionId(in.readLong());
       } else {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogOpCodes.java

@@ -68,6 +68,8 @@ public enum FSEditLogOpCodes {
   OP_REMOVE_CACHE_POOL                    ((byte) 38),
   OP_MODIFY_CACHE_DIRECTIVE     ((byte) 39),
   OP_SET_ACL                    ((byte) 40),
+  OP_ROLLING_UPGRADE_START      ((byte) 41),
+  OP_ROLLING_UPGRADE_FINALIZE   ((byte) 42),
 
   // Note that the current range of the valid OP code is 0~127
   OP_INVALID                    ((byte) -1);

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImage.java

@@ -21,11 +21,13 @@ import static org.apache.hadoop.util.Time.now;
 
 import java.io.Closeable;
 import java.io.File;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.net.URI;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
@@ -41,8 +43,8 @@ import org.apache.hadoop.hdfs.DFSUtil;
 import org.apache.hadoop.hdfs.HAUtil;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
-import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NamenodeRole;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.RollingUpgradeStartupOption;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
 import org.apache.hadoop.hdfs.server.common.InconsistentFSStateException;
 import org.apache.hadoop.hdfs.server.common.Storage;
@@ -216,13 +218,18 @@ public class FSImage implements Closeable {
       NNStorage.checkVersionUpgradable(storage.getLayoutVersion());
     }
     if (startOpt != StartupOption.UPGRADE
+        && !RollingUpgradeStartupOption.STARTED.matches(startOpt)
         && layoutVersion < Storage.LAST_PRE_UPGRADE_LAYOUT_VERSION
-        && layoutVersion != HdfsConstants.LAYOUT_VERSION) {
+        && layoutVersion != HdfsConstants.NAMENODE_LAYOUT_VERSION) {
       throw new IOException(
           "\nFile system image contains an old layout version " 
           + storage.getLayoutVersion() + ".\nAn upgrade to version "
-          + HdfsConstants.LAYOUT_VERSION + " is required.\n"
-          + "Please restart NameNode with -upgrade option.");
+          + HdfsConstants.NAMENODE_LAYOUT_VERSION + " is required.\n"
+          + "Please restart NameNode with the \""
+          + RollingUpgradeStartupOption.STARTED.getOptionString()
+          + "\" option if a rolling upgraded is already started;"
+          + " or restart NameNode with the \""
+          + StartupOption.UPGRADE + "\" to start a new upgrade.");
     }
     
     storage.processStartupOptionsForUpgrade(startOpt, layoutVersion);
@@ -261,7 +268,7 @@ public class FSImage implements Closeable {
       // just load the image
     }
     
-    return loadFSImage(target, recovery, startOpt);
+    return loadFSImage(target, startOpt, recovery);
   }
   
   /**
@@ -315,8 +322,9 @@ public class FSImage implements Closeable {
     return isFormatted;
   }
 
-  void doUpgrade(FSNamesystem target) throws IOException {
-    // Upgrade is allowed only if there are 
+  /** Check if upgrade is in progress. */
+  void checkUpgrade(FSNamesystem target) throws IOException {
+    // Upgrade or rolling upgrade is allowed only if there are 
     // no previous fs states in any of the local directories
     for (Iterator<StorageDirectory> it = storage.dirIterator(false); it.hasNext();) {
       StorageDirectory sd = it.next();
@@ -325,15 +333,37 @@ public class FSImage implements Closeable {
             "previous fs state should not exist during upgrade. "
             + "Finalize or rollback first.");
     }
+  }
+
+  /**
+   * @return true if there is rollback fsimage (for rolling upgrade) in NameNode
+   * directory.
+   */
+  public boolean hasRollbackFSImage() throws IOException {
+    final FSImageStorageInspector inspector = new FSImageTransactionalStorageInspector(
+        EnumSet.of(NameNodeFile.IMAGE_ROLLBACK));
+    storage.inspectStorageDirs(inspector);
+    try {
+      List<FSImageFile> images = inspector.getLatestImages();
+      return images != null && !images.isEmpty();
+    } catch (FileNotFoundException e) {
+      return false;
+    }
+  }
+
+  void doUpgrade(FSNamesystem target) throws IOException {
+    checkUpgrade(target);
 
     // load the latest image
+
     // Do upgrade for each directory
-    this.loadFSImage(target, null, StartupOption.UPGRADE);
+    this.loadFSImage(target, StartupOption.UPGRADE, null);
+    target.checkRollingUpgrade("upgrade namenode");
     
     long oldCTime = storage.getCTime();
     storage.cTime = now();  // generate new cTime for the state
     int oldLV = storage.getLayoutVersion();
-    storage.layoutVersion = HdfsConstants.LAYOUT_VERSION;
+    storage.layoutVersion = HdfsConstants.NAMENODE_LAYOUT_VERSION;
     
     List<StorageDirectory> errorSDs =
       Collections.synchronizedList(new ArrayList<StorageDirectory>());
@@ -393,11 +423,11 @@ public class FSImage implements Closeable {
     boolean canRollback = false;
     FSImage prevState = new FSImage(conf);
     try {
-      prevState.getStorage().layoutVersion = HdfsConstants.LAYOUT_VERSION;
+      prevState.getStorage().layoutVersion = HdfsConstants.NAMENODE_LAYOUT_VERSION;
       for (Iterator<StorageDirectory> it = storage.dirIterator(false); it.hasNext();) {
         StorageDirectory sd = it.next();
         if (!NNUpgradeUtil.canRollBack(sd, storage, prevState.getStorage(),
-            HdfsConstants.LAYOUT_VERSION)) {
+            HdfsConstants.NAMENODE_LAYOUT_VERSION)) {
           continue;
         }
         canRollback = true;
@@ -407,7 +437,7 @@ public class FSImage implements Closeable {
         // If HA is enabled, check if the shared log can be rolled back as well.
         editLog.initJournalsForWrite();
         canRollback |= editLog.canRollBackSharedLog(prevState.getStorage(),
-            HdfsConstants.LAYOUT_VERSION);
+            HdfsConstants.NAMENODE_LAYOUT_VERSION);
       }
       
       if (!canRollback)
@@ -540,13 +570,22 @@ public class FSImage implements Closeable {
    * @return whether the image should be saved
    * @throws IOException
    */
-  boolean loadFSImage(FSNamesystem target, MetaRecoveryContext recovery,
-      StartupOption startOpt) throws IOException {
-    FSImageStorageInspector inspector = storage.readAndInspectDirs();
-    FSImageFile imageFile = null;
-    
+  private boolean loadFSImage(FSNamesystem target, StartupOption startOpt,
+      MetaRecoveryContext recovery)
+      throws IOException {
+    final boolean rollingRollback
+        = RollingUpgradeStartupOption.ROLLBACK.matches(startOpt);
+    final EnumSet<NameNodeFile> nnfs;
+    if (rollingRollback) {
+      // if it is rollback of rolling upgrade, only load from the rollback image
+      nnfs = EnumSet.of(NameNodeFile.IMAGE_ROLLBACK);
+    } else {
+      // otherwise we can load from both IMAGE and IMAGE_ROLLBACK
+      nnfs = EnumSet.of(NameNodeFile.IMAGE, NameNodeFile.IMAGE_ROLLBACK);
+    }
+    final FSImageStorageInspector inspector = storage.readAndInspectDirs(nnfs);
+
     isUpgradeFinalized = inspector.isUpgradeFinalized();
- 
     List<FSImageFile> imageFiles = inspector.getLatestImages();
 
     StartupProgress prog = NameNode.getStartupProgress();
@@ -560,12 +599,22 @@ public class FSImage implements Closeable {
 
     initEditLog(startOpt);
 
-    if (LayoutVersion.supports(Feature.TXID_BASED_LAYOUT, 
-                               getLayoutVersion())) {
+    if (NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.TXID_BASED_LAYOUT, getLayoutVersion())) {
       // If we're open for write, we're either non-HA or we're the active NN, so
       // we better be able to load all the edits. If we're the standby NN, it's
       // OK to not be able to read all of edits right now.
-      long toAtLeastTxId = editLog.isOpenForWrite() ? inspector.getMaxSeenTxId() : 0;
+      // In the meanwhile, for HA upgrade, we will still write editlog thus need
+      // this toAtLeastTxId to be set to the max-seen txid
+      // For rollback in rolling upgrade, we need to set the toAtLeastTxId to
+      // the txid right before the upgrade marker.  
+      long toAtLeastTxId = editLog.isOpenForWrite() ? inspector
+          .getMaxSeenTxId() : 0;
+      if (rollingRollback) {
+        // note that the first image in imageFiles is the special checkpoint
+        // for the rolling upgrade
+        toAtLeastTxId = imageFiles.get(0).getCheckpointTxId() + 2;
+      }
       editStreams = editLog.selectInputStreams(
           imageFiles.get(0).getCheckpointTxId() + 1,
           toAtLeastTxId, recovery, false);
@@ -573,8 +622,7 @@ public class FSImage implements Closeable {
       editStreams = FSImagePreTransactionalStorageInspector
         .getEditLogStreams(storage);
     }
-    int maxOpSize = conf.getInt(DFSConfigKeys.
-          DFS_NAMENODE_MAX_OP_SIZE_KEY,
+    int maxOpSize = conf.getInt(DFSConfigKeys.DFS_NAMENODE_MAX_OP_SIZE_KEY,
         DFSConfigKeys.DFS_NAMENODE_MAX_OP_SIZE_DEFAULT);
     for (EditLogInputStream elis : editStreams) {
       elis.setMaxOpSize(maxOpSize);
@@ -587,6 +635,7 @@ public class FSImage implements Closeable {
       LOG.info("No edit log streams selected.");
     }
     
+    FSImageFile imageFile = null;
     for (int i = 0; i < imageFiles.size(); i++) {
       try {
         imageFile = imageFiles.get(i);
@@ -604,26 +653,57 @@ public class FSImage implements Closeable {
       throw new IOException("Failed to load an FSImage file!");
     }
     prog.endPhase(Phase.LOADING_FSIMAGE);
-    long txnsAdvanced = loadEdits(editStreams, target, recovery);
-    needToSave |= needsResaveBasedOnStaleCheckpoint(imageFile.getFile(),
-                                                    txnsAdvanced);
+    
+    if (!rollingRollback) {
+      long txnsAdvanced = loadEdits(editStreams, target, startOpt, recovery);
+      needToSave |= needsResaveBasedOnStaleCheckpoint(imageFile.getFile(),
+          txnsAdvanced);
+      if (RollingUpgradeStartupOption.DOWNGRADE.matches(startOpt)) {
+        // rename rollback image if it is downgrade
+        renameCheckpoint(NameNodeFile.IMAGE_ROLLBACK, NameNodeFile.IMAGE);
+      }
+    } else {
+      // Trigger the rollback for rolling upgrade. Here lastAppliedTxId equals
+      // to the last txid in rollback fsimage.
+      rollingRollback(lastAppliedTxId + 1, imageFiles.get(0).getCheckpointTxId());
+      needToSave = false;
+    }
     editLog.setNextTxId(lastAppliedTxId + 1);
     return needToSave;
   }
 
+  /** rollback for rolling upgrade. */
+  private void rollingRollback(long discardSegmentTxId, long ckptId)
+      throws IOException {
+    // discard discard unnecessary editlog segments starting from the given id
+    this.editLog.discardSegments(discardSegmentTxId);
+    // rename the special checkpoint
+    renameCheckpoint(ckptId, NameNodeFile.IMAGE_ROLLBACK, NameNodeFile.IMAGE,
+        true);
+    // purge all the checkpoints after the marker
+    archivalManager.purgeCheckpoinsAfter(NameNodeFile.IMAGE, ckptId);
+    String nameserviceId = DFSUtil.getNamenodeNameServiceId(conf);
+    if (HAUtil.isHAEnabled(conf, nameserviceId)) {
+      // close the editlog since it is currently open for write
+      this.editLog.close();
+      // reopen the editlog for read
+      this.editLog.initSharedJournalsForRead();
+    }
+  }
+
   void loadFSImageFile(FSNamesystem target, MetaRecoveryContext recovery,
       FSImageFile imageFile) throws IOException {
     LOG.debug("Planning to load image :\n" + imageFile);
     StorageDirectory sdForProperties = imageFile.sd;
     storage.readProperties(sdForProperties);
 
-    if (LayoutVersion.supports(Feature.TXID_BASED_LAYOUT,
-                               getLayoutVersion())) {
+    if (NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.TXID_BASED_LAYOUT, getLayoutVersion())) {
       // For txid-based layout, we should have a .md5 file
       // next to the image file
       loadFSImage(imageFile.getFile(), target, recovery);
-    } else if (LayoutVersion.supports(Feature.FSIMAGE_CHECKSUM,
-                                      getLayoutVersion())) {
+    } else if (NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.FSIMAGE_CHECKSUM, getLayoutVersion())) {
       // In 0.22, we have the checksum stored in the VERSION file.
       String md5 = storage.getDeprecatedProperty(
           NNStorage.DEPRECATED_MESSAGE_DIGEST_PROPERTY);
@@ -648,18 +728,21 @@ public class FSImage implements Closeable {
       // If this NN is not HA
       editLog.initJournalsForWrite();
       editLog.recoverUnclosedStreams();
-    } else if (HAUtil.isHAEnabled(conf, nameserviceId) &&
-        startOpt == StartupOption.UPGRADE) {
-      // This NN is HA, but we're doing an upgrade so init the edit log for
-      // write.
+    } else if (HAUtil.isHAEnabled(conf, nameserviceId)
+        && (startOpt == StartupOption.UPGRADE
+            || RollingUpgradeStartupOption.ROLLBACK.matches(startOpt))) {
+      // This NN is HA, but we're doing an upgrade or a rollback of rolling
+      // upgrade so init the edit log for write.
       editLog.initJournalsForWrite();
-      long sharedLogCTime = editLog.getSharedLogCTime();
-      if (this.storage.getCTime() < sharedLogCTime) {
-        throw new IOException("It looks like the shared log is already " +
-            "being upgraded but this NN has not been upgraded yet. You " +
-            "should restart this NameNode with the '" +
-            StartupOption.BOOTSTRAPSTANDBY.getName() + "' option to bring " +
-            "this NN in sync with the other.");
+      if (startOpt == StartupOption.UPGRADE) {
+        long sharedLogCTime = editLog.getSharedLogCTime();
+        if (this.storage.getCTime() < sharedLogCTime) {
+          throw new IOException("It looks like the shared log is already " +
+              "being upgraded but this NN has not been upgraded yet. You " +
+              "should restart this NameNode with the '" +
+              StartupOption.BOOTSTRAPSTANDBY.getName() + "' option to bring " +
+              "this NN in sync with the other.");
+        }
       }
       editLog.recoverUnclosedStreams();
     } else {
@@ -692,7 +775,13 @@ public class FSImage implements Closeable {
    * Load the specified list of edit files into the image.
    */
   public long loadEdits(Iterable<EditLogInputStream> editStreams,
-      FSNamesystem target, MetaRecoveryContext recovery) throws IOException {
+      FSNamesystem target) throws IOException {
+    return loadEdits(editStreams, target, null, null);
+  }
+
+  private long loadEdits(Iterable<EditLogInputStream> editStreams,
+      FSNamesystem target, StartupOption startOpt, MetaRecoveryContext recovery)
+      throws IOException {
     LOG.debug("About to load edits:\n  " + Joiner.on("\n  ").join(editStreams));
     StartupProgress prog = NameNode.getStartupProgress();
     prog.beginPhase(Phase.LOADING_EDITS);
@@ -706,7 +795,7 @@ public class FSImage implements Closeable {
         LOG.info("Reading " + editIn + " expecting start txid #" +
               (lastAppliedTxId + 1));
         try {
-          loader.loadFSEdits(editIn, lastAppliedTxId + 1, recovery);
+          loader.loadFSEdits(editIn, lastAppliedTxId + 1, startOpt, recovery);
         } finally {
           // Update lastAppliedTxId even in case of error, since some ops may
           // have been successfully applied before the error.
@@ -720,7 +809,7 @@ public class FSImage implements Closeable {
     } finally {
       FSEditLog.closeAllStreams(editStreams);
       // update the counts
-      updateCountForQuota(target.dir.rootDir);   
+      updateCountForQuota(target.dir.rootDir);
     }
     prog.endPhase(Phase.LOADING_EDITS);
     return lastAppliedTxId - prevLastAppliedTxId;
@@ -798,9 +887,12 @@ public class FSImage implements Closeable {
    */
   private void loadFSImage(File curFile, MD5Hash expectedMd5,
       FSNamesystem target, MetaRecoveryContext recovery) throws IOException {
+    // BlockPoolId is required when the FsImageLoader loads the rolling upgrade
+    // information. Make sure the ID is properly set.
+    target.setBlockPoolId(this.getBlockPoolID());
+
     FSImageFormat.LoaderDelegator loader = FSImageFormat.newLoader(conf, target);
     loader.load(curFile);
-    target.setBlockPoolId(this.getBlockPoolID());
 
     // Check that the image digest we loaded matches up with what
     // we expected
@@ -821,11 +913,11 @@ public class FSImage implements Closeable {
   /**
    * Save the contents of the FS image to the file.
    */
-  void saveFSImage(SaveNamespaceContext context, StorageDirectory sd)
-      throws IOException {
+  void saveFSImage(SaveNamespaceContext context, StorageDirectory sd,
+      NameNodeFile dstType) throws IOException {
     long txid = context.getTxId();
     File newFile = NNStorage.getStorageFile(sd, NameNodeFile.IMAGE_NEW, txid);
-    File dstFile = NNStorage.getStorageFile(sd, NameNodeFile.IMAGE, txid);
+    File dstFile = NNStorage.getStorageFile(sd, dstType, txid);
     
     FSImageFormatProtobuf.Saver saver = new FSImageFormatProtobuf.Saver(context);
     FSImageCompression compression = FSImageCompression.createCompression(conf);
@@ -849,16 +941,19 @@ public class FSImage implements Closeable {
   private class FSImageSaver implements Runnable {
     private final SaveNamespaceContext context;
     private StorageDirectory sd;
+    private final NameNodeFile nnf;
 
-    public FSImageSaver(SaveNamespaceContext context, StorageDirectory sd) {
+    public FSImageSaver(SaveNamespaceContext context, StorageDirectory sd,
+        NameNodeFile nnf) {
       this.context = context;
       this.sd = sd;
+      this.nnf = nnf;
     }
 
     @Override
     public void run() {
       try {
-        saveFSImage(context, sd);
+        saveFSImage(context, sd, nnf);
       } catch (SaveNamespaceCancelledException snce) {
         LOG.info("Cancelled image saving for " + sd.getRoot() +
             ": " + snce.getMessage());
@@ -894,17 +989,18 @@ public class FSImage implements Closeable {
    */
   public synchronized void saveNamespace(FSNamesystem source)
       throws IOException {
-    saveNamespace(source, null);
+    saveNamespace(source, NameNodeFile.IMAGE, null);
   }
   
   /**
    * Save the contents of the FS image to a new image file in each of the
    * current storage directories.
-   * @param canceler 
+   * @param canceler
    */
-  public synchronized void saveNamespace(FSNamesystem source,
+  public synchronized void saveNamespace(FSNamesystem source, NameNodeFile nnf,
       Canceler canceler) throws IOException {
     assert editLog != null : "editLog must be initialized";
+    LOG.info("Save namespace ...");
     storage.attemptRestoreRemovedStorage();
 
     boolean editLogWasOpen = editLog.isSegmentOpen();
@@ -914,7 +1010,7 @@ public class FSImage implements Closeable {
     }
     long imageTxId = getLastAppliedOrWrittenTxId();
     try {
-      saveFSImageInAllDirs(source, imageTxId, canceler);
+      saveFSImageInAllDirs(source, nnf, imageTxId, canceler);
       storage.writeAll();
     } finally {
       if (editLogWasOpen) {
@@ -933,12 +1029,11 @@ public class FSImage implements Closeable {
    */
   protected synchronized void saveFSImageInAllDirs(FSNamesystem source, long txid)
       throws IOException {
-    saveFSImageInAllDirs(source, txid, null);
+    saveFSImageInAllDirs(source, NameNodeFile.IMAGE, txid, null);
   }
 
-  protected synchronized void saveFSImageInAllDirs(FSNamesystem source, long txid,
-      Canceler canceler)
-      throws IOException {    
+  private synchronized void saveFSImageInAllDirs(FSNamesystem source,
+      NameNodeFile nnf, long txid, Canceler canceler) throws IOException {
     StartupProgress prog = NameNode.getStartupProgress();
     prog.beginPhase(Phase.SAVING_CHECKPOINT);
     if (storage.getNumStorageDirs(NameNodeDirType.IMAGE) == 0) {
@@ -956,7 +1051,7 @@ public class FSImage implements Closeable {
       for (Iterator<StorageDirectory> it
              = storage.dirIterator(NameNodeDirType.IMAGE); it.hasNext();) {
         StorageDirectory sd = it.next();
-        FSImageSaver saver = new FSImageSaver(ctx, sd);
+        FSImageSaver saver = new FSImageSaver(ctx, sd, nnf);
         Thread saveThread = new Thread(saver, saver.toString());
         saveThreads.add(saveThread);
         saveThread.start();
@@ -975,11 +1070,11 @@ public class FSImage implements Closeable {
         assert false : "should have thrown above!";
       }
   
-      renameCheckpoint(txid);
+      renameCheckpoint(txid, NameNodeFile.IMAGE_NEW, nnf, false);
   
       // Since we now have a new checkpoint, we can clean up some
       // old edit logs and checkpoints.
-      purgeOldStorage();
+      purgeOldStorage(nnf);
     } finally {
       // Notify any threads waiting on the checkpoint to be canceled
       // that it is complete.
@@ -993,23 +1088,24 @@ public class FSImage implements Closeable {
    * Purge any files in the storage directories that are no longer
    * necessary.
    */
-  public void purgeOldStorage() {
+  void purgeOldStorage(NameNodeFile nnf) {
     try {
-      archivalManager.purgeOldStorage();
+      archivalManager.purgeOldStorage(nnf);
     } catch (Exception e) {
-      LOG.warn("Unable to purge old storage", e);
+      LOG.warn("Unable to purge old storage " + nnf.getName(), e);
     }
   }
 
   /**
-   * Renames new image
+   * Rename FSImage with the specific txid
    */
-  private void renameCheckpoint(long txid) throws IOException {
+  private void renameCheckpoint(long txid, NameNodeFile fromNnf,
+      NameNodeFile toNnf, boolean renameMD5) throws IOException {
     ArrayList<StorageDirectory> al = null;
 
     for (StorageDirectory sd : storage.dirIterable(NameNodeDirType.IMAGE)) {
       try {
-        renameCheckpointInDir(sd, txid);
+        renameImageFileInDir(sd, fromNnf, toNnf, txid, renameMD5);
       } catch (IOException ioe) {
         LOG.warn("Unable to rename checkpoint in " + sd, ioe);
         if (al == null) {
@@ -1020,7 +1116,33 @@ public class FSImage implements Closeable {
     }
     if(al != null) storage.reportErrorsOnDirectories(al);
   }
-  
+
+  /**
+   * Rename all the fsimage files with the specific NameNodeFile type. The
+   * associated checksum files will also be renamed.
+   */
+  void renameCheckpoint(NameNodeFile fromNnf, NameNodeFile toNnf)
+      throws IOException {
+    ArrayList<StorageDirectory> al = null;
+    FSImageTransactionalStorageInspector inspector =
+        new FSImageTransactionalStorageInspector(EnumSet.of(fromNnf));
+    storage.inspectStorageDirs(inspector);
+    for (FSImageFile image : inspector.getFoundImages()) {
+      try {
+        renameImageFileInDir(image.sd, fromNnf, toNnf, image.txId, true);
+      } catch (IOException ioe) {
+        LOG.warn("Unable to rename checkpoint in " + image.sd, ioe);
+        if (al == null) {
+          al = Lists.newArrayList();
+        }
+        al.add(image.sd);
+      }
+    }
+    if(al != null) {
+      storage.reportErrorsOnDirectories(al);
+    }
+  }
+
   /**
    * Deletes the checkpoint file in every storage directory,
    * since the checkpoint was cancelled.
@@ -1038,23 +1160,24 @@ public class FSImage implements Closeable {
     storage.reportErrorsOnDirectories(al);
   }
 
-
-  private void renameCheckpointInDir(StorageDirectory sd, long txid)
-      throws IOException {
-    File ckpt = NNStorage.getStorageFile(sd, NameNodeFile.IMAGE_NEW, txid);
-    File curFile = NNStorage.getStorageFile(sd, NameNodeFile.IMAGE, txid);
-    // renameTo fails on Windows if the destination file 
-    // already exists.
+  private void renameImageFileInDir(StorageDirectory sd, NameNodeFile fromNnf,
+      NameNodeFile toNnf, long txid, boolean renameMD5) throws IOException {
+    final File fromFile = NNStorage.getStorageFile(sd, fromNnf, txid);
+    final File toFile = NNStorage.getStorageFile(sd, toNnf, txid);
+    // renameTo fails on Windows if the destination file already exists.
     if(LOG.isDebugEnabled()) {
-      LOG.debug("renaming  " + ckpt.getAbsolutePath() 
-                + " to " + curFile.getAbsolutePath());
+      LOG.debug("renaming  " + fromFile.getAbsolutePath() 
+                + " to " + toFile.getAbsolutePath());
     }
-    if (!ckpt.renameTo(curFile)) {
-      if (!curFile.delete() || !ckpt.renameTo(curFile)) {
-        throw new IOException("renaming  " + ckpt.getAbsolutePath() + " to "  + 
-            curFile.getAbsolutePath() + " FAILED");
+    if (!fromFile.renameTo(toFile)) {
+      if (!toFile.delete() || !fromFile.renameTo(toFile)) {
+        throw new IOException("renaming  " + fromFile.getAbsolutePath() + " to "  + 
+            toFile.getAbsolutePath() + " FAILED");
       }
-    }    
+    }
+    if (renameMD5) {
+      MD5FileUtils.renameMD5File(fromFile, toFile);
+    }
   }
 
   CheckpointSignature rollEditLog() throws IOException {
@@ -1135,13 +1258,13 @@ public class FSImage implements Closeable {
    * renames the image from fsimage_N.ckpt to fsimage_N and also
    * saves the related .md5 file into place.
    */
-  public synchronized void saveDigestAndRenameCheckpointImage(
+  public synchronized void saveDigestAndRenameCheckpointImage(NameNodeFile nnf,
       long txid, MD5Hash digest) throws IOException {
     // Write and rename MD5 file
     List<StorageDirectory> badSds = Lists.newArrayList();
     
     for (StorageDirectory sd : storage.dirIterable(NameNodeDirType.IMAGE)) {
-      File imageFile = NNStorage.getImageFile(sd, txid);
+      File imageFile = NNStorage.getImageFile(sd, nnf, txid);
       try {
         MD5FileUtils.saveMD5File(imageFile, digest);
       } catch (IOException ioe) {
@@ -1153,7 +1276,7 @@ public class FSImage implements Closeable {
     CheckpointFaultInjector.getInstance().afterMD5Rename();
     
     // Rename image from tmp file
-    renameCheckpoint(txid);
+    renameCheckpoint(txid, NameNodeFile.IMAGE_NEW, nnf, false);
     // So long as this is the newest image available,
     // advertise it as such to other checkpointers
     // from now on

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageFormat.java

@@ -328,9 +328,10 @@ public class FSImageFormat {
               "imgVersion " + imgVersion +
               " expected to be " + getLayoutVersion());
         }
-        boolean supportSnapshot = LayoutVersion.supports(Feature.SNAPSHOT,
-            imgVersion);
-        if (LayoutVersion.supports(Feature.ADD_LAYOUT_FLAGS, imgVersion)) {
+        boolean supportSnapshot = NameNodeLayoutVersion.supports(
+            LayoutVersion.Feature.SNAPSHOT, imgVersion);
+        if (NameNodeLayoutVersion.supports(
+            LayoutVersion.Feature.ADD_LAYOUT_FLAGS, imgVersion)) {
           LayoutFlags.read(in);
         }
 
@@ -343,7 +344,8 @@ public class FSImageFormat {
         long genstamp = in.readLong();
         namesystem.setGenerationStampV1(genstamp);
         
-        if (LayoutVersion.supports(Feature.SEQUENTIAL_BLOCK_ID, imgVersion)) {
+        if (NameNodeLayoutVersion.supports(
+            LayoutVersion.Feature.SEQUENTIAL_BLOCK_ID, imgVersion)) {
           // read the starting generation stamp for sequential block IDs
           genstamp = in.readLong();
           namesystem.setGenerationStampV2(genstamp);
@@ -365,14 +367,16 @@ public class FSImageFormat {
 
         // read the transaction ID of the last edit represented by
         // this image
-        if (LayoutVersion.supports(Feature.STORED_TXIDS, imgVersion)) {
+        if (NameNodeLayoutVersion.supports(
+            LayoutVersion.Feature.STORED_TXIDS, imgVersion)) {
           imgTxId = in.readLong();
         } else {
           imgTxId = 0;
         }
 
         // read the last allocated inode id in the fsimage
-        if (LayoutVersion.supports(Feature.ADD_INODE_ID, imgVersion)) {
+        if (NameNodeLayoutVersion.supports(
+            LayoutVersion.Feature.ADD_INODE_ID, imgVersion)) {
           long lastInodeId = in.readLong();
           namesystem.resetLastInodeId(lastInodeId);
           if (LOG.isDebugEnabled()) {
@@ -391,7 +395,8 @@ public class FSImageFormat {
 
         // read compression related info
         FSImageCompression compression;
-        if (LayoutVersion.supports(Feature.FSIMAGE_COMPRESSION, imgVersion)) {
+        if (NameNodeLayoutVersion.supports(
+            LayoutVersion.Feature.FSIMAGE_COMPRESSION, imgVersion)) {
           compression = FSImageCompression.readCompressionHeader(conf, in);
         } else {
           compression = FSImageCompression.createNoopCompression();
@@ -404,8 +409,8 @@ public class FSImageFormat {
         LOG.info("Number of files = " + numFiles);
         prog.setTotal(Phase.LOADING_FSIMAGE, step, numFiles);
         Counter counter = prog.getCounter(Phase.LOADING_FSIMAGE, step);
-        if (LayoutVersion.supports(Feature.FSIMAGE_NAME_OPTIMIZATION,
-            imgVersion)) {
+        if (NameNodeLayoutVersion.supports(
+            LayoutVersion.Feature.FSIMAGE_NAME_OPTIMIZATION, imgVersion)) {
           if (supportSnapshot) {
             loadLocalNameINodesWithSnapshot(numFiles, in, counter);
           } else {
@@ -462,9 +467,10 @@ public class FSImageFormat {
      */
     private void loadLocalNameINodesWithSnapshot(long numFiles, DataInput in,
         Counter counter) throws IOException {
-      assert LayoutVersion.supports(Feature.FSIMAGE_NAME_OPTIMIZATION,
-          getLayoutVersion());
-      assert LayoutVersion.supports(Feature.SNAPSHOT, getLayoutVersion());
+      assert NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.FSIMAGE_NAME_OPTIMIZATION, getLayoutVersion());
+      assert NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.SNAPSHOT, getLayoutVersion());
       
       // load root
       loadRoot(in, counter);
@@ -483,8 +489,8 @@ public class FSImageFormat {
    */  
    private void loadLocalNameINodes(long numFiles, DataInput in, Counter counter)
        throws IOException {
-     assert LayoutVersion.supports(Feature.FSIMAGE_NAME_OPTIMIZATION,
-         getLayoutVersion());
+     assert NameNodeLayoutVersion.supports(
+         LayoutVersion.Feature.FSIMAGE_NAME_OPTIMIZATION, getLayoutVersion());
      assert numFiles > 0;
 
      // load root
@@ -710,18 +716,21 @@ public class FSImageFormat {
   INode loadINode(final byte[] localName, boolean isSnapshotINode,
       DataInput in, Counter counter) throws IOException {
     final int imgVersion = getLayoutVersion();
-    if (LayoutVersion.supports(Feature.SNAPSHOT, imgVersion)) {
+    if (NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.SNAPSHOT, imgVersion)) {
       namesystem.getFSDirectory().verifyINodeName(localName);
     }
 
-    long inodeId = LayoutVersion.supports(Feature.ADD_INODE_ID, imgVersion) ? 
-           in.readLong() : namesystem.allocateNewInodeId();
+    long inodeId = NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.ADD_INODE_ID, imgVersion) ? in.readLong()
+        : namesystem.allocateNewInodeId();
     
     final short replication = namesystem.getBlockManager().adjustReplication(
         in.readShort());
     final long modificationTime = in.readLong();
     long atime = 0;
-    if (LayoutVersion.supports(Feature.FILE_ACCESS_TIME, imgVersion)) {
+    if (NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.FILE_ACCESS_TIME, imgVersion)) {
       atime = in.readLong();
     }
     final long blockSize = in.readLong();
@@ -741,7 +750,8 @@ public class FSImageFormat {
       String clientMachine = "";
       boolean underConstruction = false;
       FileDiffList fileDiffs = null;
-      if (LayoutVersion.supports(Feature.SNAPSHOT, imgVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.SNAPSHOT, imgVersion)) {
         // read diffs
         fileDiffs = SnapshotFSImageFormat.loadFileDiffList(in, this);
 
@@ -778,14 +788,16 @@ public class FSImageFormat {
       //read quotas
       final long nsQuota = in.readLong();
       long dsQuota = -1L;
-      if (LayoutVersion.supports(Feature.DISKSPACE_QUOTA, imgVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.DISKSPACE_QUOTA, imgVersion)) {
         dsQuota = in.readLong();
       }
 
       //read snapshot info
       boolean snapshottable = false;
       boolean withSnapshot = false;
-      if (LayoutVersion.supports(Feature.SNAPSHOT, imgVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.SNAPSHOT, imgVersion)) {
         snapshottable = in.readBoolean();
         if (!snapshottable) {
           withSnapshot = in.readBoolean();
@@ -848,7 +860,8 @@ public class FSImageFormat {
         throws IOException {
       final int layoutVersion = getLayoutVersion();
       
-      if (!LayoutVersion.supports(Feature.OPTIMIZE_SNAPSHOT_INODES, layoutVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.OPTIMIZE_SNAPSHOT_INODES, layoutVersion)) {
         return loadINodeWithLocalName(true, in, false).asFile();
       }
   
@@ -869,7 +882,8 @@ public class FSImageFormat {
         throws IOException {
       final int layoutVersion = getLayoutVersion();
       
-      if (!LayoutVersion.supports(Feature.OPTIMIZE_SNAPSHOT_INODES, layoutVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.OPTIMIZE_SNAPSHOT_INODES, layoutVersion)) {
         return loadINodeWithLocalName(true, in, false).asDirectory();
       }
   
@@ -904,7 +918,8 @@ public class FSImageFormat {
         INodeFile oldnode = null;
         boolean inSnapshot = false;
         if (path != null && FSDirectory.isReservedName(path) && 
-            LayoutVersion.supports(Feature.ADD_INODE_ID, getLayoutVersion())) {
+            NameNodeLayoutVersion.supports(
+                LayoutVersion.Feature.ADD_INODE_ID, getLayoutVersion())) {
           // TODO: for HDFS-5428, we use reserved path for those INodeFileUC in 
           // snapshot. If we support INode ID in the layout version, we can use
           // the inode id to find the oldnode.
@@ -937,7 +952,8 @@ public class FSImageFormat {
         throws IOException {
       int imgVersion = getLayoutVersion();
 
-      if (!LayoutVersion.supports(Feature.DELEGATION_TOKEN, imgVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.DELEGATION_TOKEN, imgVersion)) {
         //SecretManagerState is not available.
         //This must not happen if security is turned on.
         return; 
@@ -947,7 +963,8 @@ public class FSImageFormat {
 
     private void loadCacheManagerState(DataInput in) throws IOException {
       int imgVersion = getLayoutVersion();
-      if (!LayoutVersion.supports(Feature.CACHING, imgVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.CACHING, imgVersion)) {
         return;
       }
       namesystem.getCacheManager().loadStateCompat(in);
@@ -1009,7 +1026,7 @@ public class FSImageFormat {
     for (String key: HdfsConstants.RESERVED_PATH_COMPONENTS) {
       renameReservedMap.put(
           key,
-          key + "." + LayoutVersion.getCurrentLayoutVersion() + "."
+          key + "." + HdfsConstants.NAMENODE_LAYOUT_VERSION + "."
               + "UPGRADE_RENAMED");
     }
   }
@@ -1057,7 +1074,7 @@ public class FSImageFormat {
       final int layoutVersion) {
     final String oldPath = path;
     // If any known LVs aren't supported, we're doing an upgrade
-    if (!LayoutVersion.supports(Feature.ADD_INODE_ID, layoutVersion)) {
+    if (!NameNodeLayoutVersion.supports(Feature.ADD_INODE_ID, layoutVersion)) {
       String[] components = INode.getPathNames(path);
       // Only need to worry about the root directory
       if (components.length > 1) {
@@ -1068,7 +1085,7 @@ public class FSImageFormat {
         path = DFSUtil.strings2PathString(components);
       }
     }
-    if (!LayoutVersion.supports(Feature.SNAPSHOT, layoutVersion)) {
+    if (!NameNodeLayoutVersion.supports(Feature.SNAPSHOT, layoutVersion)) {
       String[] components = INode.getPathNames(path);
       // Special case the root path
       if (components.length == 0) {
@@ -1106,7 +1123,7 @@ public class FSImageFormat {
   private static byte[] renameReservedComponentOnUpgrade(byte[] component,
       final int layoutVersion) {
     // If the LV doesn't support snapshots, we're doing an upgrade
-    if (!LayoutVersion.supports(Feature.SNAPSHOT, layoutVersion)) {
+    if (!NameNodeLayoutVersion.supports(Feature.SNAPSHOT, layoutVersion)) {
       if (Arrays.equals(component, HdfsConstants.DOT_SNAPSHOT_DIR_BYTES)) {
         Preconditions.checkArgument(
             renameReservedMap != null &&
@@ -1127,7 +1144,7 @@ public class FSImageFormat {
   private static byte[] renameReservedRootComponentOnUpgrade(byte[] component,
       final int layoutVersion) {
     // If the LV doesn't support inode IDs, we're doing an upgrade
-    if (!LayoutVersion.supports(Feature.ADD_INODE_ID, layoutVersion)) {
+    if (!NameNodeLayoutVersion.supports(Feature.ADD_INODE_ID, layoutVersion)) {
       if (Arrays.equals(component, FSDirectory.DOT_RESERVED)) {
         Preconditions.checkArgument(
             renameReservedMap != null &&
@@ -1210,7 +1227,7 @@ public class FSImageFormat {
       DigestOutputStream fos = new DigestOutputStream(fout, digester);
       DataOutputStream out = new DataOutputStream(fos);
       try {
-        out.writeInt(HdfsConstants.LAYOUT_VERSION);
+        out.writeInt(HdfsConstants.NAMENODE_LAYOUT_VERSION);
         LayoutFlags.write(out);
         // We use the non-locked version of getNamespaceInfo here since
         // the coordinating thread of saveNamespace already has read-locked

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageFormatProtobuf.java

@@ -42,7 +42,6 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
-import org.apache.hadoop.hdfs.protocol.LayoutVersion;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.CacheDirectiveInfoProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.CachePoolInfoProto;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenSecretManager;
@@ -281,6 +280,12 @@ public final class FSImageFormatProtobuf {
       fsn.setGenerationStampV1Limit(s.getGenstampV1Limit());
       fsn.setLastAllocatedBlockId(s.getLastAllocatedBlockId());
       imgTxId = s.getTransactionId();
+      if (s.hasRollingUpgradeStartTime()
+          && fsn.getFSImage().hasRollbackFSImage()) {
+        // we set the rollingUpgradeInfo only when we make sure we have the
+        // rollback image
+        fsn.setRollingUpgradeInfo(true, s.getRollingUpgradeStartTime());
+      }
     }
 
     private void loadStringTableSection(InputStream in) throws IOException {
@@ -430,7 +435,7 @@ public final class FSImageFormatProtobuf {
 
       FileSummary.Builder b = FileSummary.newBuilder()
           .setOndiskVersion(FSImageUtil.FILE_VERSION)
-          .setLayoutVersion(LayoutVersion.getCurrentLayoutVersion());
+          .setLayoutVersion(NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
 
       codec = compression.getImageCodec();
       if (codec != null) {
@@ -521,6 +526,9 @@ public final class FSImageFormatProtobuf {
       // from the actual saver thread, there's a potential of a
       // fairness-related deadlock. See the comments on HDFS-2223.
       b.setNamespaceId(fsn.unprotectedGetNamespaceInfo().getNamespaceID());
+      if (fsn.isRollingUpgrade()) {
+        b.setRollingUpgradeStartTime(fsn.getRollingUpgradeInfo().getStartTime());
+      }
       NameSystemSection s = b.build();
       s.writeDelimitedTo(out);
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageSerialization.java

@@ -33,7 +33,6 @@ import org.apache.hadoop.hdfs.protocol.Block;
 import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
 import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
-import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
 import org.apache.hadoop.hdfs.server.blockmanagement.BlockInfo;
 import org.apache.hadoop.hdfs.server.blockmanagement.BlockInfoUnderConstruction;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.BlockUCState;
@@ -118,8 +117,9 @@ public class FSImageSerialization {
       DataInput in, FSNamesystem fsNamesys, int imgVersion)
       throws IOException {
     byte[] name = readBytes(in);
-    long inodeId = LayoutVersion.supports(Feature.ADD_INODE_ID, imgVersion) ? in
-        .readLong() : fsNamesys.allocateNewInodeId();
+    long inodeId = NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.ADD_INODE_ID, imgVersion) ? in.readLong()
+        : fsNamesys.allocateNewInodeId();
     short blockReplication = in.readShort();
     long modificationTime = in.readLong();
     long preferredBlockSize = in.readLong();

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageTransactionalStorageInspector.java

@@ -22,6 +22,7 @@ import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.EnumSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.regex.Matcher;
@@ -33,7 +34,9 @@ import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
 import org.apache.hadoop.hdfs.server.namenode.NNStorage.NameNodeDirType;
 import org.apache.hadoop.hdfs.server.namenode.NNStorage.NameNodeFile;
+
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Lists;
 
 class FSImageTransactionalStorageInspector extends FSImageStorageInspector {
   public static final Log LOG = LogFactory.getLog(
@@ -45,8 +48,28 @@ class FSImageTransactionalStorageInspector extends FSImageStorageInspector {
   List<FSImageFile> foundImages = new ArrayList<FSImageFile>();
   private long maxSeenTxId = 0;
   
-  private static final Pattern IMAGE_REGEX = Pattern.compile(
-    NameNodeFile.IMAGE.getName() + "_(\\d+)");
+  private final List<Pattern> namePatterns = Lists.newArrayList();
+
+  FSImageTransactionalStorageInspector() {
+    this(EnumSet.of(NameNodeFile.IMAGE));
+  }
+
+  FSImageTransactionalStorageInspector(EnumSet<NameNodeFile> nnfs) {
+    for (NameNodeFile nnf : nnfs) {
+      Pattern pattern = Pattern.compile(nnf.getName() + "_(\\d+)");
+      namePatterns.add(pattern);
+    }
+  }
+
+  private Matcher matchPattern(String name) {
+    for (Pattern p : namePatterns) {
+      Matcher m = p.matcher(name);
+      if (m.matches()) {
+        return m;
+      }
+    }
+    return null;
+  }
 
   @Override
   public void inspectDirectory(StorageDirectory sd) throws IOException {
@@ -81,8 +104,8 @@ class FSImageTransactionalStorageInspector extends FSImageStorageInspector {
       String name = f.getName();
       
       // Check for fsimage_*
-      Matcher imageMatch = IMAGE_REGEX.matcher(name);
-      if (imageMatch.matches()) {
+      Matcher imageMatch = this.matchPattern(name);
+      if (imageMatch != null) {
         if (sd.getStorageDirType().isOfType(NameNodeDirType.IMAGE)) {
           try {
             long txid = Long.valueOf(imageMatch.group(1));

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSImageUtil.java

@@ -25,7 +25,6 @@ import java.util.Arrays;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
-import org.apache.hadoop.hdfs.protocol.LayoutVersion;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
 import org.apache.hadoop.hdfs.server.namenode.FSImageFormatProtobuf.Loader;
 import org.apache.hadoop.hdfs.server.namenode.FsImageProto.FileSummary;
@@ -71,7 +70,7 @@ public final class FSImageUtil {
           + summary.getOndiskVersion());
     }
 
-    if (!LayoutVersion.supports(Feature.PROTOBUF_FORMAT,
+    if (!NameNodeLayoutVersion.supports(Feature.PROTOBUF_FORMAT,
         summary.getLayoutVersion())) {
       throw new IOException("Unsupported layout version "
           + summary.getLayoutVersion());

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -36,10 +36,10 @@ import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_HA_STANDBY_CHECKPOINTS_KE
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_ACCESSTIME_PRECISION_DEFAULT;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_ACCESSTIME_PRECISION_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_AUDIT_LOGGERS_KEY;
-import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_AUDIT_LOG_TOKEN_TRACKING_ID_DEFAULT;
-import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_AUDIT_LOG_TOKEN_TRACKING_ID_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_AUDIT_LOG_ASYNC_DEFAULT;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_AUDIT_LOG_ASYNC_KEY;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_AUDIT_LOG_TOKEN_TRACKING_ID_DEFAULT;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_AUDIT_LOG_TOKEN_TRACKING_ID_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_CHECKPOINT_TXNS_DEFAULT;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_CHECKPOINT_TXNS_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_DEFAULT_AUDIT_LOGGER_NAME;
@@ -173,6 +173,8 @@ import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
 import org.apache.hadoop.hdfs.protocol.QuotaExceededException;
 import org.apache.hadoop.hdfs.protocol.RecoveryInProgressException;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeException;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeInfo;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport.DiffReportEntry;
 import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
@@ -194,20 +196,20 @@ import org.apache.hadoop.hdfs.server.blockmanagement.OutOfV1GenerationStampsExce
 import org.apache.hadoop.hdfs.server.common.GenerationStamp;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.BlockUCState;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NamenodeRole;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.RollingUpgradeStartupOption;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
 import org.apache.hadoop.hdfs.server.common.Storage;
 import org.apache.hadoop.hdfs.server.common.Storage.StorageDirType;
 import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
 import org.apache.hadoop.hdfs.server.common.Util;
 import org.apache.hadoop.hdfs.server.namenode.FsImageProto.SecretManagerSection;
-import org.apache.hadoop.hdfs.server.namenode.FsImageProto.SecretManagerSection.PersistToken;
 import org.apache.hadoop.hdfs.server.namenode.INode.BlocksMapUpdateInfo;
 import org.apache.hadoop.hdfs.server.namenode.JournalSet.JournalAndStream;
 import org.apache.hadoop.hdfs.server.namenode.LeaseManager.Lease;
+import org.apache.hadoop.hdfs.server.namenode.NNStorage.NameNodeFile;
 import org.apache.hadoop.hdfs.server.namenode.NameNode.OperationCategory;
 import org.apache.hadoop.hdfs.server.namenode.ha.EditLogTailer;
 import org.apache.hadoop.hdfs.server.namenode.ha.HAContext;
-import org.apache.hadoop.hdfs.server.namenode.ha.HAState;
 import org.apache.hadoop.hdfs.server.namenode.ha.StandbyCheckpointer;
 import org.apache.hadoop.hdfs.server.namenode.metrics.FSNamesystemMBean;
 import org.apache.hadoop.hdfs.server.namenode.metrics.NameNodeMetrics;
@@ -404,6 +406,14 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
   private final CacheManager cacheManager;
   private final DatanodeStatistics datanodeStatistics;
 
+  private RollingUpgradeInfo rollingUpgradeInfo = null;
+  /**
+   * A flag that indicates whether the checkpointer should checkpoint a rollback
+   * fsimage. The edit log tailer sets this flag. The checkpoint will create a
+   * rollback fsimage if the flag is true, and then change the flag to false.
+   */
+  private volatile boolean needRollbackFsImage;
+
   // Block pool ID used by this namenode
   private String blockPoolId;
 
@@ -497,7 +507,10 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
   private HAContext haContext;
 
   private final boolean haEnabled;
-  
+
+  /** flag indicating whether replication queues have been initialized */
+  boolean initializedReplQueues = false;
+
   /**
    * Whether the namenode is in the middle of starting the active service
    */
@@ -622,8 +635,7 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
    * @return an FSNamesystem which contains the loaded namespace
    * @throws IOException if loading fails
    */
-  public static FSNamesystem loadFromDisk(Configuration conf)
-      throws IOException {
+  static FSNamesystem loadFromDisk(Configuration conf) throws IOException {
 
     checkConfiguration(conf);
     FSImage fsImage = new FSImage(conf,
@@ -636,10 +648,8 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     }
 
     long loadStart = now();
-    String nameserviceId = DFSUtil.getNamenodeNameServiceId(conf);
     try {
-      namesystem.loadFSImage(startOpt, fsImage,
-        HAUtil.isHAEnabled(conf, nameserviceId));
+      namesystem.loadFSImage(startOpt);
     } catch (IOException ioe) {
       LOG.warn("Encountered exception loading fsimage", ioe);
       fsImage.close();
@@ -865,8 +875,9 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     return Collections.unmodifiableList(auditLoggers);
   }
 
-  void loadFSImage(StartupOption startOpt, FSImage fsImage, boolean haEnabled)
-      throws IOException {
+  private void loadFSImage(StartupOption startOpt) throws IOException {
+    final FSImage fsImage = getFSImage();
+
     // format before starting up if requested
     if (startOpt == StartupOption.FORMAT) {
       
@@ -879,8 +890,15 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     try {
       // We shouldn't be calling saveNamespace if we've come up in standby state.
       MetaRecoveryContext recovery = startOpt.createRecoveryContext();
-      boolean needToSave =
-        fsImage.recoverTransitionRead(startOpt, this, recovery) && !haEnabled;
+      final boolean staleImage
+          = fsImage.recoverTransitionRead(startOpt, this, recovery);
+      if (RollingUpgradeStartupOption.ROLLBACK.matches(startOpt)) {
+        rollingUpgradeInfo = null;
+      }
+      final boolean needToSave = staleImage && !haEnabled && !isRollingUpgrade(); 
+      LOG.info("Need to save fs image? " + needToSave
+          + " (staleImage=" + staleImage + ", haEnabled=" + haEnabled
+          + ", isRollingUpgrade=" + isRollingUpgrade() + ")");
       if (needToSave) {
         fsImage.saveNamespace(this);
       } else {
@@ -943,8 +961,7 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     try {
       nnResourceChecker = new NameNodeResourceChecker(conf);
       checkAvailableResources();
-      assert safeMode != null &&
-        !safeMode.isPopulatingReplQueues();
+      assert safeMode != null && !isPopulatingReplQueues();
       StartupProgress prog = NameNode.getStartupProgress();
       prog.beginPhase(Phase.SAFEMODE);
       prog.setTotal(Phase.SAFEMODE, STEP_AWAITING_REPORTED_BLOCKS,
@@ -999,12 +1016,12 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
         blockManager.clearQueues();
         blockManager.processAllPendingDNMessages();
 
-        if (!isInSafeMode() ||
-            (isInSafeMode() && safeMode.isPopulatingReplQueues())) {
+        // Only need to re-process the queue, If not in SafeMode.
+        if (!isInSafeMode()) {
           LOG.info("Reprocessing replication and invalidation queues");
-          blockManager.processMisReplicatedBlocks();
+          initializeReplQueues();
         }
-        
+
         if (LOG.isDebugEnabled()) {
           LOG.debug("NameNode metadata after re-processing " +
               "replication and invalidation queues during failover:\n" +
@@ -1044,12 +1061,21 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
       startingActiveService = false;
     }
   }
-  
+
   private boolean inActiveState() {
     return haContext != null &&
         haContext.getState().getServiceState() == HAServiceState.ACTIVE;
   }
   
+  /**
+   * Initialize replication queues.
+   */
+  private void initializeReplQueues() {
+    LOG.info("initializing replication queues");
+    blockManager.processMisReplicatedBlocks();
+    initializedReplQueues = true;
+  }
+
   /**
    * @return Whether the namenode is transitioning to active state and is in the
    *         middle of the {@link #startActiveServices()}
@@ -1095,6 +1121,9 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
       cacheManager.clearDirectiveStats();
       blockManager.getDatanodeManager().clearPendingCachingCommands();
       blockManager.getDatanodeManager().setShouldSendCachingCommands(false);
+      // Don't want to keep replication queues when not in Active.
+      blockManager.clearQueues();
+      initializedReplQueues = false;
     } finally {
       writeUnlock();
     }
@@ -1122,6 +1151,16 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     }
   }
 
+  /**
+   * Called when the NN is in Standby state and the editlog tailer tails the
+   * OP_ROLLING_UPGRADE_START.
+   */
+  void triggerRollbackCheckpoint() {
+    setNeedRollbackFsImage(true);
+    if (standbyCheckpointer != null) {
+      standbyCheckpointer.triggerRollbackCheckpoint();
+    }
+  }
 
   /**
    * Called while the NN is in Standby state, but just about to be
@@ -4193,23 +4232,24 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
         throws IOException {
     readLock();
     try {
+      //get datanode commands
       final int maxTransfer = blockManager.getMaxReplicationStreams()
           - xmitsInProgress;
       DatanodeCommand[] cmds = blockManager.getDatanodeManager().handleHeartbeat(
           nodeReg, reports, blockPoolId, cacheCapacity, cacheUsed,
           xceiverCount, maxTransfer, failedVolumes);
-      return new HeartbeatResponse(cmds, createHaStatusHeartbeat());
+      
+      //create ha status
+      final NNHAStatusHeartbeat haState = new NNHAStatusHeartbeat(
+          haContext.getState().getServiceState(),
+          getFSImage().getLastAppliedOrWrittenTxId());
+
+      return new HeartbeatResponse(cmds, haState, rollingUpgradeInfo);
     } finally {
       readUnlock();
     }
   }
 
-  private NNHAStatusHeartbeat createHaStatusHeartbeat() {
-    HAState state = haContext.getState();
-    return new NNHAStatusHeartbeat(state.getServiceState(),
-        getFSImage().getLastAppliedOrWrittenTxId());
-  }
-
   /**
    * Returns whether or not there were available resources at the last check of
    * resources.
@@ -4493,6 +4533,7 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     readLock();
     try {
       checkOperation(OperationCategory.UNCHECKED);
+
       if (!isInSafeMode()) {
         throw new IOException("Safe mode should be turned ON "
             + "in order to create namespace image.");
@@ -4594,7 +4635,6 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     private int safeReplication;
     /** threshold for populating needed replication queues */
     private double replQueueThreshold;
-      
     // internal fields
     /** Time when threshold was reached.
      * <br> -1 safe mode is off
@@ -4612,8 +4652,6 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     private int blockReplQueueThreshold;
     /** time of the last status printout */
     private long lastStatusReport = 0;
-    /** flag indicating whether replication queues have been initialized */
-    boolean initializedReplQueues = false;
     /** Was safemode entered automatically because available resources were low. */
     private boolean resourcesLow = false;
     /** Should safemode adjust its block totals as blocks come in */
@@ -4673,7 +4711,7 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
      * 
      * @see SafeModeInfo
      */
-    private SafeModeInfo(boolean resourcesLow, boolean isReplQueuesInited) {
+    private SafeModeInfo(boolean resourcesLow) {
       this.threshold = 1.5f;  // this threshold can never be reached
       this.datanodeThreshold = Integer.MAX_VALUE;
       this.extension = Integer.MAX_VALUE;
@@ -4682,7 +4720,6 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
       this.blockTotal = -1;
       this.blockSafe = -1;
       this.resourcesLow = resourcesLow;
-      this.initializedReplQueues = isReplQueuesInited;
       enter();
       reportStatus("STATE* Safe mode is ON.", true);
     }
@@ -4696,13 +4733,6 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
       return this.reached >= 0;
     }
       
-    /**
-     * Check if we are populating replication queues.
-     */
-    private synchronized boolean isPopulatingReplQueues() {
-      return initializedReplQueues;
-    }
-
     /**
      * Enter safe mode.
      */
@@ -4749,21 +4779,6 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
       }
     }
 
-    /**
-     * Initialize replication queues.
-     */
-    private synchronized void initializeReplQueues() {
-      LOG.info("initializing replication queues");
-      assert !isPopulatingReplQueues() : "Already initialized repl queues";
-      long startTimeMisReplicatedScan = now();
-      blockManager.processMisReplicatedBlocks();
-      initializedReplQueues = true;
-      NameNode.stateChangeLog.info("STATE* Replication Queue initialization "
-          + "scan for invalid, over- and under-replicated blocks "
-          + "completed in " + (now() - startTimeMisReplicatedScan)
-          + " msec");
-    }
-
     /**
      * Check whether we have reached the threshold for 
      * initializing replication queues.
@@ -4811,7 +4826,8 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
       if (smmthread == null && needEnter()) {
         enter();
         // check if we are ready to initialize replication queues
-        if (canInitializeReplQueues() && !isPopulatingReplQueues()) {
+        if (canInitializeReplQueues() && !isPopulatingReplQueues()
+            && !haEnabled) {
           initializeReplQueues();
         }
         reportStatus("STATE* Safe mode ON.", false);
@@ -4836,7 +4852,7 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
       }
 
       // check if we are ready to initialize replication queues
-      if (canInitializeReplQueues() && !isPopulatingReplQueues()) {
+      if (canInitializeReplQueues() && !isPopulatingReplQueues() && !haEnabled) {
         initializeReplQueues();
       }
     }
@@ -5146,11 +5162,7 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     if (!shouldPopulateReplQueues()) {
       return false;
     }
-    // safeMode is volatile, and may be set to null at any time
-    SafeModeInfo safeMode = this.safeMode;
-    if (safeMode == null)
-      return true;
-    return safeMode.isPopulatingReplQueues();
+    return initializedReplQueues;
   }
 
   private boolean shouldPopulateReplQueues() {
@@ -5270,7 +5282,7 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
         getEditLog().logSyncAll();
       }
       if (!isInSafeMode()) {
-        safeMode = new SafeModeInfo(resourcesLow, isPopulatingReplQueues());
+        safeMode = new SafeModeInfo(resourcesLow);
         return;
       }
       if (resourcesLow) {
@@ -5345,8 +5357,8 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     NamenodeCommand cmd = null;
     try {
       checkOperation(OperationCategory.CHECKPOINT);
-
       checkNameNodeSafeMode("Checkpoint not started");
+      
       LOG.info("Start checkpoint for " + backupNode.getAddress());
       cmd = getFSImage().startCheckpoint(backupNode, activeNamenode);
       getEditLog().logSync();
@@ -7134,6 +7146,173 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     }
   }
 
+  RollingUpgradeInfo queryRollingUpgrade() throws IOException {
+    checkSuperuserPrivilege();
+    checkOperation(OperationCategory.READ);
+    readLock();
+    try {
+      if (rollingUpgradeInfo != null) {
+        boolean hasRollbackImage = this.getFSImage().hasRollbackFSImage();
+        rollingUpgradeInfo.setCreatedRollbackImages(hasRollbackImage);
+      }
+      return rollingUpgradeInfo;
+    } finally {
+      readUnlock();
+    }
+  }
+
+  RollingUpgradeInfo startRollingUpgrade() throws IOException {
+    checkSuperuserPrivilege();
+    checkOperation(OperationCategory.WRITE);
+    writeLock();
+    try {
+      checkOperation(OperationCategory.WRITE);
+      long startTime = now();
+      if (!haEnabled) { // for non-HA, we require NN to be in safemode
+        startRollingUpgradeInternalForNonHA(startTime);
+      } else { // for HA, NN cannot be in safemode
+        checkNameNodeSafeMode("Failed to start rolling upgrade");
+        startRollingUpgradeInternal(startTime);
+      }
+
+      getEditLog().logStartRollingUpgrade(rollingUpgradeInfo.getStartTime());
+      if (haEnabled) {
+        // roll the edit log to make sure the standby NameNode can tail
+        getFSImage().rollEditLog();
+      }
+    } finally {
+      writeUnlock();
+    }
+
+    getEditLog().logSync();
+    if (auditLog.isInfoEnabled() && isExternalInvocation()) {
+      logAuditEvent(true, "startRollingUpgrade", null, null, null);
+    }
+    return rollingUpgradeInfo;
+  }
+
+  /**
+   * Update internal state to indicate that a rolling upgrade is in progress.
+   * @param startTime
+   */
+  void startRollingUpgradeInternal(long startTime)
+      throws IOException {
+    checkRollingUpgrade("start rolling upgrade");
+    getFSImage().checkUpgrade(this);
+    setRollingUpgradeInfo(false, startTime);
+  }
+
+  /**
+   * Update internal state to indicate that a rolling upgrade is in progress for
+   * non-HA setup. This requires the namesystem is in SafeMode and after doing a
+   * checkpoint for rollback the namesystem will quit the safemode automatically 
+   */
+  private void startRollingUpgradeInternalForNonHA(long startTime)
+      throws IOException {
+    Preconditions.checkState(!haEnabled);
+    if (!isInSafeMode()) {
+      throw new IOException("Safe mode should be turned ON "
+          + "in order to create namespace image.");
+    }
+    checkRollingUpgrade("start rolling upgrade");
+    getFSImage().checkUpgrade(this);
+    // in non-HA setup, we do an extra ckpt to generate a rollback image
+    getFSImage().saveNamespace(this, NameNodeFile.IMAGE_ROLLBACK, null);
+    LOG.info("Successfully saved namespace for preparing rolling upgrade.");
+
+    // leave SafeMode automatically
+    setSafeMode(SafeModeAction.SAFEMODE_LEAVE);
+    setRollingUpgradeInfo(true, startTime);
+  }
+
+  void setRollingUpgradeInfo(boolean createdRollbackImages, long startTime) {
+    rollingUpgradeInfo = new RollingUpgradeInfo(blockPoolId,
+        createdRollbackImages, startTime, 0L);
+  }
+
+  public void setCreatedRollbackImages(boolean created) {
+    if (rollingUpgradeInfo != null) {
+      rollingUpgradeInfo.setCreatedRollbackImages(created);
+    }
+  }
+
+  public RollingUpgradeInfo getRollingUpgradeInfo() {
+    return rollingUpgradeInfo;
+  }
+
+  public boolean isNeedRollbackFsImage() {
+    return needRollbackFsImage;
+  }
+
+  public void setNeedRollbackFsImage(boolean needRollbackFsImage) {
+    this.needRollbackFsImage = needRollbackFsImage;
+  }
+
+  @Override  // NameNodeMXBean
+  public RollingUpgradeInfo.Bean getRollingUpgradeStatus() {
+    readLock();
+    try {
+      RollingUpgradeInfo upgradeInfo = getRollingUpgradeInfo();
+      if (upgradeInfo != null) {
+        return new RollingUpgradeInfo.Bean(upgradeInfo);
+      }
+      return null;
+    } finally {
+      readUnlock();
+    }
+  }
+
+  /** Is rolling upgrade in progress? */
+  public boolean isRollingUpgrade() {
+    return rollingUpgradeInfo != null;
+  }
+
+  void checkRollingUpgrade(String action) throws RollingUpgradeException {
+    if (isRollingUpgrade()) {
+      throw new RollingUpgradeException("Failed to " + action
+          + " since a rolling upgrade is already in progress."
+          + " Existing rolling upgrade info:\n" + rollingUpgradeInfo);
+    }
+  }
+
+  RollingUpgradeInfo finalizeRollingUpgrade() throws IOException {
+    checkSuperuserPrivilege();
+    checkOperation(OperationCategory.WRITE);
+    writeLock();
+    final RollingUpgradeInfo returnInfo;
+    try {
+      checkOperation(OperationCategory.WRITE);
+      checkNameNodeSafeMode("Failed to finalize rolling upgrade");
+
+      returnInfo = finalizeRollingUpgradeInternal(now());
+      getEditLog().logFinalizeRollingUpgrade(returnInfo.getFinalizeTime());
+      getFSImage().saveNamespace(this);
+      getFSImage().renameCheckpoint(NameNodeFile.IMAGE_ROLLBACK,
+          NameNodeFile.IMAGE);
+    } finally {
+      writeUnlock();
+    }
+
+    // getEditLog().logSync() is not needed since it does saveNamespace 
+
+    if (auditLog.isInfoEnabled() && isExternalInvocation()) {
+      logAuditEvent(true, "finalizeRollingUpgrade", null, null, null);
+    }
+    return returnInfo;
+  }
+
+  RollingUpgradeInfo finalizeRollingUpgradeInternal(long finalizeTime)
+      throws RollingUpgradeException {
+    if (!isRollingUpgrade()) {
+      throw new RollingUpgradeException(
+          "Failed to finalize rolling upgrade since there is no rolling upgrade in progress.");
+    }
+
+    final long startTime = rollingUpgradeInfo.getStartTime();
+    rollingUpgradeInfo = null;
+    return new RollingUpgradeInfo(blockPoolId, false, startTime, finalizeTime);
+  }
+
   long addCacheDirective(CacheDirectiveInfo directive, EnumSet<CacheFlag> flags)
       throws IOException {
     checkOperation(OperationCategory.WRITE);

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FileJournalManager.java

@@ -34,6 +34,7 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.server.common.Storage;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NodeType;
 import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
 import org.apache.hadoop.hdfs.server.common.StorageErrorReporter;
 import org.apache.hadoop.hdfs.server.common.StorageInfo;
@@ -197,6 +198,32 @@ public class FileJournalManager implements JournalManager {
     
     return ret;
   }
+  
+  /**
+   * Discard all editlog segments whose first txid is greater than or equal to
+   * the given txid, by renaming them with suffix ".trash".
+   */
+  private void discardEditLogSegments(long startTxId) throws IOException {
+    File currentDir = sd.getCurrentDir();
+    List<EditLogFile> allLogFiles = matchEditLogs(currentDir);
+    List<EditLogFile> toTrash = Lists.newArrayList();
+    LOG.info("Discard the EditLog files, the given start txid is " + startTxId);
+    // go through the editlog files to make sure the startTxId is right at the
+    // segment boundary
+    for (EditLogFile elf : allLogFiles) {
+      if (elf.getFirstTxId() >= startTxId) {
+        toTrash.add(elf);
+      } else {
+        Preconditions.checkState(elf.getLastTxId() < startTxId);
+      }
+    }
+
+    for (EditLogFile elf : toTrash) {
+      // rename these editlog file as .trash
+      elf.moveAsideTrashFile(startTxId);
+      LOG.info("Trash the EditLog file " + elf);
+    }
+  }
 
   /**
    * returns matching edit logs via the log directory. Simple helper function
@@ -466,6 +493,11 @@ public class FileJournalManager implements JournalManager {
       renameSelf(".corrupt");
     }
 
+    void moveAsideTrashFile(long markerTxid) throws IOException {
+      assert this.getFirstTxId() >= markerTxid;
+      renameSelf(".trash");
+    }
+
     public void moveAsideEmptyFile() throws IOException {
       assert lastTxId == HdfsConstants.INVALID_TXID;
       renameSelf(".empty");
@@ -529,9 +561,14 @@ public class FileJournalManager implements JournalManager {
     NNUpgradeUtil.doRollBack(sd);
   }
 
+  @Override
+  public void discardSegments(long startTxid) throws IOException {
+    discardEditLogSegments(startTxid);
+  }
+
   @Override
   public long getJournalCTime() throws IOException {
-    StorageInfo sInfo = new StorageInfo();
+    StorageInfo sInfo = new StorageInfo((NodeType)null);
     sInfo.readProperties(sd);
     return sInfo.getCTime();
   }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/GetImageServlet.java

@@ -43,6 +43,7 @@ import org.apache.hadoop.hdfs.HAUtil;
 import org.apache.hadoop.hdfs.server.common.JspHelper;
 import org.apache.hadoop.hdfs.server.common.Storage;
 import org.apache.hadoop.hdfs.server.common.StorageInfo;
+import org.apache.hadoop.hdfs.server.namenode.NNStorage.NameNodeFile;
 import org.apache.hadoop.hdfs.server.namenode.metrics.NameNodeMetrics;
 import org.apache.hadoop.hdfs.server.protocol.RemoteEditLog;
 import org.apache.hadoop.hdfs.util.DataTransferThrottler;
@@ -77,7 +78,8 @@ public class GetImageServlet extends HttpServlet {
   private static final String END_TXID_PARAM = "endTxId";
   private static final String STORAGEINFO_PARAM = "storageInfo";
   private static final String LATEST_FSIMAGE_VALUE = "latest";
-  
+  private static final String IMAGE_FILE_TYPE = "imageFile";
+
   private static Set<Long> currentlyDownloadingCheckpoints =
     Collections.<Long>synchronizedSet(new HashSet<Long>());
   
@@ -86,7 +88,7 @@ public class GetImageServlet extends HttpServlet {
                     final HttpServletResponse response
                     ) throws ServletException, IOException {
     try {
-      ServletContext context = getServletContext();
+      final ServletContext context = getServletContext();
       final FSImage nnImage = NameNodeHttpServer.getFsImageFromContext(context);
       final GetImageParams parsedParams = new GetImageParams(request, response);
       final Configuration conf = (Configuration) context
@@ -126,7 +128,8 @@ public class GetImageServlet extends HttpServlet {
               imageFile = nnImage.getStorage().getHighestFsImageName();
             } else {
               errorMessage += " with txid " + txid;
-              imageFile = nnImage.getStorage().getFsImageName(txid);
+              imageFile = nnImage.getStorage().getFsImage(txid,
+                  EnumSet.of(NameNodeFile.IMAGE, NameNodeFile.IMAGE_ROLLBACK));
             }
             if (imageFile == null) {
               throw new IOException(errorMessage);
@@ -154,6 +157,7 @@ public class GetImageServlet extends HttpServlet {
             }
           } else if (parsedParams.isPutImage()) {
             final long txid = parsedParams.getTxId();
+            final NameNodeFile nnf = parsedParams.getNameNodeFile();
 
             if (! currentlyDownloadingCheckpoints.add(txid)) {
               response.sendError(HttpServletResponse.SC_CONFLICT,
@@ -163,7 +167,7 @@ public class GetImageServlet extends HttpServlet {
             }
 
             try {
-              if (nnImage.getStorage().findImageFile(txid) != null) {
+              if (nnImage.getStorage().findImageFile(nnf, txid) != null) {
                 response.sendError(HttpServletResponse.SC_CONFLICT,
                     "Another checkpointer already uploaded an checkpoint " +
                     "for txid " + txid);
@@ -177,11 +181,15 @@ public class GetImageServlet extends HttpServlet {
               
               long start = now();
               // issue a HTTP get request to download the new fsimage 
-              MD5Hash downloadImageDigest =
-                TransferFsImage.downloadImageToStorage(
-                        parsedParams.getInfoServer(conf), txid,
-                        nnImage.getStorage(), true);
-              nnImage.saveDigestAndRenameCheckpointImage(txid, downloadImageDigest);
+              MD5Hash downloadImageDigest = TransferFsImage
+                  .downloadImageToStorage(parsedParams.getInfoServer(conf),
+                      txid, nnImage.getStorage(), true);
+              nnImage.saveDigestAndRenameCheckpointImage(nnf, txid,
+                  downloadImageDigest);
+              if (nnf == NameNodeFile.IMAGE_ROLLBACK) {
+                    NameNodeHttpServer.getNameNodeFromContext(context)
+                        .getNamesystem().setCreatedRollbackImages(true);
+              }
 
               if (metrics != null) { // Metrics non-null only when used inside name node
                 long elapsed = now() - start;
@@ -190,7 +198,7 @@ public class GetImageServlet extends HttpServlet {
               
               // Now that we have a new checkpoint, we might be able to
               // remove some old ones.
-              nnImage.purgeOldStorage();
+              nnImage.purgeOldStorage(nnf);
             } finally {
               currentlyDownloadingCheckpoints.remove(txid);
             }
@@ -314,9 +322,12 @@ public class GetImageServlet extends HttpServlet {
     return "getimage=1&" + TXID_PARAM + "=" + LATEST_FSIMAGE_VALUE;
   }
 
-  static String getParamStringForImage(long txid,
+  static String getParamStringForImage(NameNodeFile nnf, long txid,
       StorageInfo remoteStorageInfo) {
+    final String imageType = nnf == null ? "" : "&" + IMAGE_FILE_TYPE + "="
+        + nnf.name();
     return "getimage=1&" + TXID_PARAM + "=" + txid
+      + imageType
       + "&" + STORAGEINFO_PARAM + "=" +
       remoteStorageInfo.toColonSeparatedString();
   }
@@ -329,7 +340,7 @@ public class GetImageServlet extends HttpServlet {
           remoteStorageInfo.toColonSeparatedString();
   }
   
-  static String getParamStringToPutImage(long txid,
+  static String getParamStringToPutImage(NameNodeFile nnf, long txid,
       URL url, Storage storage) {
     InetSocketAddress imageListenAddress = NetUtils.createSocketAddr(url
         .getAuthority());
@@ -338,6 +349,7 @@ public class GetImageServlet extends HttpServlet {
         : imageListenAddress.getHostName();
     return "putimage=1" +
       "&" + TXID_PARAM + "=" + txid +
+      "&" + IMAGE_FILE_TYPE + "=" + nnf.name() +
       "&port=" + imageListenAddress.getPort() +
       (machine != null ? "&machine=" + machine : "")
       + "&" + STORAGEINFO_PARAM + "=" +
@@ -351,6 +363,7 @@ public class GetImageServlet extends HttpServlet {
     private boolean isPutImage;
     private int remoteport;
     private String machineName;
+    private NameNodeFile nnf;
     private long startTxId, endTxId, txId;
     private String storageInfoString;
     private boolean fetchLatest;
@@ -375,6 +388,9 @@ public class GetImageServlet extends HttpServlet {
           isGetImage = true;
           try {
             txId = ServletUtil.parseLongParam(request, TXID_PARAM);
+            String imageType = ServletUtil.getParameter(request, IMAGE_FILE_TYPE);
+            nnf = imageType == null ? NameNodeFile.IMAGE : NameNodeFile
+                .valueOf(imageType);
           } catch (NumberFormatException nfe) {
             if (request.getParameter(TXID_PARAM).equals(LATEST_FSIMAGE_VALUE)) {
               fetchLatest = true;
@@ -389,6 +405,9 @@ public class GetImageServlet extends HttpServlet {
         } else if (key.equals("putimage")) { 
           isPutImage = true;
           txId = ServletUtil.parseLongParam(request, TXID_PARAM);
+          String imageType = ServletUtil.getParameter(request, IMAGE_FILE_TYPE);
+          nnf = imageType == null ? NameNodeFile.IMAGE : NameNodeFile
+              .valueOf(imageType);
         } else if (key.equals("port")) { 
           remoteport = new Integer(val[0]).intValue();
         } else if (key.equals("machine")) {
@@ -419,7 +438,12 @@ public class GetImageServlet extends HttpServlet {
       Preconditions.checkState(isGetImage || isPutImage);
       return txId;
     }
-    
+
+    public NameNodeFile getNameNodeFile() {
+      Preconditions.checkState(isPutImage || isGetImage);
+      return nnf;
+    }
+
     public long getStartTxId() {
       Preconditions.checkState(isGetEdit);
       return startTxId;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/JournalManager.java

@@ -109,7 +109,15 @@ public interface JournalManager extends Closeable, FormatConfirmable,
    * roll back their state should just return without error.
    */
   void doRollback() throws IOException;
-  
+
+  /**
+   * Discard the segments whose first txid is >= the given txid.
+   * @param startTxId The given txid should be right at the segment boundary, 
+   * i.e., it should be the first txid of some segment, if segment corresponding
+   * to the txid exists.
+   */
+  void discardSegments(long startTxId) throws IOException;
+
   /**
    * @return the CTime of the journal manager.
    */

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/JournalSet.java

@@ -699,6 +699,12 @@ public class JournalSet implements JournalManager {
     throw new UnsupportedOperationException();
   }
 
+  @Override
+  public void discardSegments(long startTxId) throws IOException {
+    // This operation is handled by FSEditLog directly.
+    throw new UnsupportedOperationException();
+  }
+
   @Override
   public long getJournalCTime() throws IOException {
     // This operation is handled by FSEditLog directly.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NNStorage.java

@@ -25,6 +25,7 @@ import java.net.URI;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
@@ -38,7 +39,6 @@ import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.hdfs.DFSUtil;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
-import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NodeType;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
 import org.apache.hadoop.hdfs.server.common.InconsistentFSStateException;
@@ -47,13 +47,12 @@ import org.apache.hadoop.hdfs.server.common.StorageErrorReporter;
 import org.apache.hadoop.hdfs.server.common.Util;
 import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
 import org.apache.hadoop.hdfs.util.PersistentLongFile;
-
 import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.net.DNS;
 import org.apache.hadoop.util.Time;
 
-import com.google.common.base.Preconditions;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
 
 /**
@@ -69,19 +68,21 @@ public class NNStorage extends Storage implements Closeable,
   //
   // The filenames used for storing the images
   //
-  enum NameNodeFile {
+  public enum NameNodeFile {
     IMAGE     ("fsimage"),
     TIME      ("fstime"), // from "old" pre-HDFS-1073 format
     SEEN_TXID ("seen_txid"),
     EDITS     ("edits"),
     IMAGE_NEW ("fsimage.ckpt"),
+    IMAGE_ROLLBACK("fsimage_rollback"),
     EDITS_NEW ("edits.new"), // from "old" pre-HDFS-1073 format
     EDITS_INPROGRESS ("edits_inprogress"),
     EDITS_TMP ("edits_tmp");
 
     private String fileName = null;
     private NameNodeFile(String name) { this.fileName = name; }
-    String getName() { return fileName; }
+    @VisibleForTesting
+    public String getName() { return fileName; }
   }
 
   /**
@@ -90,7 +91,8 @@ public class NNStorage extends Storage implements Closeable,
    * or of type EDITS which stores edits or of type IMAGE_AND_EDITS which
    * stores both fsimage and edits.
    */
-  static enum NameNodeDirType implements StorageDirType {
+  @VisibleForTesting
+  public static enum NameNodeDirType implements StorageDirType {
     UNDEFINED,
     IMAGE,
     EDITS,
@@ -498,21 +500,42 @@ public class NNStorage extends Storage implements Closeable,
   }
 
   /**
-   * Return the name of the image file.
-   * @return The name of the first image file.
+   * @return The first image file with the given txid and image type.
    */
-  public File getFsImageName(long txid) {
-    StorageDirectory sd = null;
-    for (Iterator<StorageDirectory> it =
-      dirIterator(NameNodeDirType.IMAGE); it.hasNext();) {
-      sd = it.next();
-      File fsImage = getStorageFile(sd, NameNodeFile.IMAGE, txid);
-      if(FileUtil.canRead(sd.getRoot()) && fsImage.exists())
+  public File getFsImageName(long txid, NameNodeFile nnf) {
+    for (Iterator<StorageDirectory> it = dirIterator(NameNodeDirType.IMAGE);
+        it.hasNext();) {
+      StorageDirectory sd = it.next();
+      File fsImage = getStorageFile(sd, nnf, txid);
+      if (FileUtil.canRead(sd.getRoot()) && fsImage.exists()) {
         return fsImage;
+      }
     }
     return null;
   }
-  
+
+  /**
+   * @return The first image file whose txid is the same with the given txid and
+   * image type is one of the given types.
+   */
+  public File getFsImage(long txid, EnumSet<NameNodeFile> nnfs) {
+    for (Iterator<StorageDirectory> it = dirIterator(NameNodeDirType.IMAGE);
+        it.hasNext();) {
+      StorageDirectory sd = it.next();
+      for (NameNodeFile nnf : nnfs) {
+        File fsImage = getStorageFile(sd, nnf, txid);
+        if (FileUtil.canRead(sd.getRoot()) && fsImage.exists()) {
+          return fsImage;
+        }
+      }
+    }
+    return null;
+  }
+
+  public File getFsImageName(long txid) {
+    return getFsImageName(txid, NameNodeFile.IMAGE);
+  }
+
   public File getHighestFsImageName() {
     return getFsImageName(getMostRecentCheckpointTxId());
   }
@@ -533,7 +556,7 @@ public class NNStorage extends Storage implements Closeable,
    */
   public void format(NamespaceInfo nsInfo) throws IOException {
     Preconditions.checkArgument(nsInfo.getLayoutVersion() == 0 ||
-        nsInfo.getLayoutVersion() == HdfsConstants.LAYOUT_VERSION,
+        nsInfo.getLayoutVersion() == HdfsConstants.NAMENODE_LAYOUT_VERSION,
         "Bad layout version: %s", nsInfo.getLayoutVersion());
     
     this.setStorageInfo(nsInfo);
@@ -552,7 +575,7 @@ public class NNStorage extends Storage implements Closeable,
   }
   
   public void format() throws IOException {
-    this.layoutVersion = HdfsConstants.LAYOUT_VERSION;
+    this.layoutVersion = HdfsConstants.NAMENODE_LAYOUT_VERSION;
     for (Iterator<StorageDirectory> it =
                            dirIterator(); it.hasNext();) {
       StorageDirectory sd = it.next();
@@ -589,7 +612,8 @@ public class NNStorage extends Storage implements Closeable,
     }
 
     // Set Block pool ID in version with federation support
-    if (versionSupportsFederation()) {
+    if (NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.FEDERATION, getLayoutVersion())) {
       String sbpid = props.getProperty("blockpoolID");
       setBlockPoolID(sd.getRoot(), sbpid);
     }
@@ -614,7 +638,7 @@ public class NNStorage extends Storage implements Closeable,
    * This should only be used during upgrades.
    */
   String getDeprecatedProperty(String prop) {
-    assert getLayoutVersion() > HdfsConstants.LAYOUT_VERSION :
+    assert getLayoutVersion() > HdfsConstants.NAMENODE_LAYOUT_VERSION :
       "getDeprecatedProperty should only be done when loading " +
       "storage from past versions during upgrade.";
     return deprecatedProperties.get(prop);
@@ -636,7 +660,8 @@ public class NNStorage extends Storage implements Closeable,
                            ) throws IOException {
     super.setPropertiesFromFields(props, sd);
     // Set blockpoolID in version with federation support
-    if (versionSupportsFederation()) {
+    if (NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.FEDERATION, getLayoutVersion())) {
       props.setProperty("blockpoolID", blockpoolID);
     }
   }
@@ -656,20 +681,26 @@ public class NNStorage extends Storage implements Closeable,
 
   @VisibleForTesting
   public static String getCheckpointImageFileName(long txid) {
-    return String.format("%s_%019d",
-                         NameNodeFile.IMAGE_NEW.getName(), txid);
+    return getNameNodeFileName(NameNodeFile.IMAGE_NEW, txid);
   }
 
   @VisibleForTesting
   public static String getImageFileName(long txid) {
-    return String.format("%s_%019d",
-                         NameNodeFile.IMAGE.getName(), txid);
+    return getNameNodeFileName(NameNodeFile.IMAGE, txid);
   }
-  
+
+  @VisibleForTesting
+  public static String getRollbackImageFileName(long txid) {
+    return getNameNodeFileName(NameNodeFile.IMAGE_ROLLBACK, txid);
+  }
+
+  private static String getNameNodeFileName(NameNodeFile nnf, long txid) {
+    return String.format("%s_%019d", nnf.getName(), txid);
+  }
+
   @VisibleForTesting
   public static String getInProgressEditsFileName(long startTxId) {
-    return String.format("%s_%019d", NameNodeFile.EDITS_INPROGRESS.getName(),
-                         startTxId);
+    return getNameNodeFileName(NameNodeFile.EDITS_INPROGRESS, startTxId);
   }
   
   static File getInProgressEditsFile(StorageDirectory sd, long startTxId) {
@@ -687,12 +718,11 @@ public class NNStorage extends Storage implements Closeable,
     return new File(sd.getCurrentDir(),
         getTemporaryEditsFileName(startTxId, endTxId, timestamp));
   }
-  
-  static File getImageFile(StorageDirectory sd, long txid) {
-    return new File(sd.getCurrentDir(),
-        getImageFileName(txid));
+
+  static File getImageFile(StorageDirectory sd, NameNodeFile nnf, long txid) {
+    return new File(sd.getCurrentDir(), getNameNodeFileName(nnf, txid));
   }
-  
+
   @VisibleForTesting
   public static String getFinalizedEditsFileName(long startTxId, long endTxId) {
     return String.format("%s_%019d-%019d", NameNodeFile.EDITS.getName(),
@@ -720,12 +750,12 @@ public class NNStorage extends Storage implements Closeable,
   }
     
   /**
-   * Return the first readable image file for the given txid, or null
-   * if no such image can be found
+   * Return the first readable image file for the given txid and image type, or
+   * null if no such image can be found
    */
-  File findImageFile(long txid) {
+  File findImageFile(NameNodeFile nnf, long txid) {
     return findFile(NameNodeDirType.IMAGE,
-        getImageFileName(txid));
+        getNameNodeFileName(nnf, txid));
   }
 
   /**
@@ -808,7 +838,8 @@ public class NNStorage extends Storage implements Closeable,
       // If upgrade from a release that does not support federation,
       // if clusterId is provided in the startupOptions use it.
       // Else generate a new cluster ID      
-      if (!LayoutVersion.supports(Feature.FEDERATION, layoutVersion)) {
+      if (!NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.FEDERATION, layoutVersion)) {
         if (startOpt.getClusterId() == null) {
           startOpt.setClusterId(newClusterID());
         }
@@ -969,7 +1000,7 @@ public class NNStorage extends Storage implements Closeable,
    * <b>Note:</b> this can mutate the storage info fields (ctime, version, etc).
    * @throws IOException if no valid storage dirs are found or no valid layout version
    */
-  FSImageStorageInspector readAndInspectDirs()
+  FSImageStorageInspector readAndInspectDirs(EnumSet<NameNodeFile> fileTypes)
       throws IOException {
     Integer layoutVersion = null;
     boolean multipleLV = false;
@@ -1005,8 +1036,9 @@ public class NNStorage extends Storage implements Closeable,
     // (ie edits_<txnid>) then use the new inspector, which will ignore
     // the old format dirs.
     FSImageStorageInspector inspector;
-    if (LayoutVersion.supports(Feature.TXID_BASED_LAYOUT, getLayoutVersion())) {
-      inspector = new FSImageTransactionalStorageInspector();
+    if (NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.TXID_BASED_LAYOUT, getLayoutVersion())) {
+      inspector = new FSImageTransactionalStorageInspector(fileTypes);
     } else {
       inspector = new FSImagePreTransactionalStorageInspector();
     }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NNStorageRetentionManager.java

@@ -22,6 +22,7 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.EnumSet;
 import java.util.List;
 import java.util.TreeSet;
 
@@ -31,6 +32,7 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.server.namenode.FSImageStorageInspector.FSImageFile;
 import org.apache.hadoop.hdfs.server.namenode.FileJournalManager.EditLogFile;
+import org.apache.hadoop.hdfs.server.namenode.NNStorage.NameNodeFile;
 import org.apache.hadoop.hdfs.util.MD5FileUtils;
 
 import com.google.common.base.Preconditions;
@@ -88,13 +90,35 @@ public class NNStorageRetentionManager {
     this(conf, storage, purgeableLogs, new DeletionStoragePurger());
   }
 
-  public void purgeOldStorage() throws IOException {
+  void purgeCheckpoints(NameNodeFile nnf) throws IOException {
+    purgeCheckpoinsAfter(nnf, -1);
+  }
+
+  void purgeCheckpoinsAfter(NameNodeFile nnf, long fromTxId)
+      throws IOException {
     FSImageTransactionalStorageInspector inspector =
-      new FSImageTransactionalStorageInspector();
+        new FSImageTransactionalStorageInspector(EnumSet.of(nnf));
+    storage.inspectStorageDirs(inspector);
+    for (FSImageFile image : inspector.getFoundImages()) {
+      if (image.getCheckpointTxId() > fromTxId) {
+        purger.purgeImage(image);
+      }
+    }
+  }
+
+  void purgeOldStorage(NameNodeFile nnf) throws IOException {
+    FSImageTransactionalStorageInspector inspector =
+        new FSImageTransactionalStorageInspector(EnumSet.of(nnf));
     storage.inspectStorageDirs(inspector);
 
     long minImageTxId = getImageTxIdToRetain(inspector);
     purgeCheckpointsOlderThan(inspector, minImageTxId);
+    
+    if (nnf == NameNodeFile.IMAGE_ROLLBACK) {
+      // do not purge edits for IMAGE_ROLLBACK.
+      return;
+    }
+
     // If fsimage_N is the image we want to keep, then we need to keep
     // all txns > N. We can remove anything < N+1, since fsimage_N
     // reflects the state up to and including N. However, we also

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNode.java

@@ -21,6 +21,7 @@ import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Joiner;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
+
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.HadoopIllegalArgumentException;
@@ -40,6 +41,7 @@ import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NamenodeRole;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.RollingUpgradeStartupOption;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.StartupOption;
 import org.apache.hadoop.hdfs.server.namenode.ha.*;
 import org.apache.hadoop.hdfs.server.namenode.metrics.NameNodeMetrics;
@@ -65,6 +67,7 @@ import org.apache.hadoop.util.ServicePlugin;
 import org.apache.hadoop.util.StringUtils;
 
 import javax.management.ObjectName;
+
 import java.io.IOException;
 import java.io.PrintStream;
 import java.net.InetSocketAddress;
@@ -206,6 +209,9 @@ public class NameNode implements NameNodeStatusMXBean {
         " [" + StartupOption.CLUSTERID.getName() + " cid]" +
         " [" + StartupOption.RENAMERESERVED.getName() + "<k-v pairs>] ] | ["
       + StartupOption.ROLLBACK.getName() + "] | ["
+      + StartupOption.ROLLINGUPGRADE.getName() + " <"
+      + RollingUpgradeStartupOption.DOWNGRADE.name().toLowerCase() + "|"
+      + RollingUpgradeStartupOption.ROLLBACK.name().toLowerCase() + "> ] | ["
       + StartupOption.FINALIZE.getName() + "] | ["
       + StartupOption.IMPORT.getName() + "] | ["
       + StartupOption.INITIALIZESHAREDEDITS.getName() + "] | ["
@@ -1126,6 +1132,10 @@ public class NameNode implements NameNodeStatusMXBean {
             return null;
           }
         }
+      } else if (StartupOption.ROLLINGUPGRADE.getName().equalsIgnoreCase(cmd)) {
+        startOpt = StartupOption.ROLLINGUPGRADE;
+        ++i;
+        startOpt.setRollingUpgradeStartupOption(args[i]);
       } else if (StartupOption.ROLLBACK.getName().equalsIgnoreCase(cmd)) {
         startOpt = StartupOption.ROLLBACK;
       } else if (StartupOption.FINALIZE.getName().equalsIgnoreCase(cmd)) {
@@ -1171,7 +1181,7 @@ public class NameNode implements NameNodeStatusMXBean {
   }
 
   private static void setStartupOption(Configuration conf, StartupOption opt) {
-    conf.set(DFS_NAMENODE_STARTUP_KEY, opt.toString());
+    conf.set(DFS_NAMENODE_STARTUP_KEY, opt.name());
   }
 
   static StartupOption getStartupOption(Configuration conf) {
@@ -1201,7 +1211,7 @@ public class NameNode implements NameNodeStatusMXBean {
     FSNamesystem fsn = null;
     try {
       fsn = FSNamesystem.loadFromDisk(conf);
-      fsn.saveNamespace();
+      fsn.getFSImage().saveNamespace(fsn);
       MetaRecoveryContext.LOG.info("RECOVERY COMPLETE");
     } catch (IOException e) {
       MetaRecoveryContext.LOG.info("RECOVERY FAILED: caught exception", e);
@@ -1217,6 +1227,7 @@ public class NameNode implements NameNodeStatusMXBean {
 
   public static NameNode createNameNode(String argv[], Configuration conf)
       throws IOException {
+    LOG.info("createNameNode " + Arrays.asList(argv));
     if (conf == null)
       conf = new HdfsConfiguration();
     // Parse out some generic args into Configuration.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeLayoutVersion.java

@@ -0,0 +1,98 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs.server.namenode;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.SortedSet;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.hdfs.protocol.LayoutVersion;
+import org.apache.hadoop.hdfs.protocol.LayoutVersion.FeatureInfo;
+import org.apache.hadoop.hdfs.protocol.LayoutVersion.LayoutFeature;
+
+
+@InterfaceAudience.Private
+public class NameNodeLayoutVersion { 
+  /** Build layout version and corresponding feature matrix */
+  public final static Map<Integer, SortedSet<LayoutFeature>> FEATURES
+      = new HashMap<Integer, SortedSet<LayoutFeature>>();
+
+  public static final int CURRENT_LAYOUT_VERSION
+      = LayoutVersion.getCurrentLayoutVersion(Feature.values());
+
+  static {
+    LayoutVersion.updateMap(FEATURES, LayoutVersion.Feature.values());
+    LayoutVersion.updateMap(FEATURES, NameNodeLayoutVersion.Feature.values());
+  }
+  
+  public static SortedSet<LayoutFeature> getFeatures(int lv) {
+    return FEATURES.get(lv);
+  }
+
+  public static boolean supports(final LayoutFeature f, final int lv) {
+    return LayoutVersion.supports(FEATURES, f, lv);
+  }
+
+  /**
+   * Enums for features that change the layout version.
+   * <br><br>
+   * To add a new layout version:
+   * <ul>
+   * <li>Define a new enum constant with a short enum name, the new layout version 
+   * and description of the added feature.</li>
+   * <li>When adding a layout version with an ancestor that is not same as
+   * its immediate predecessor, use the constructor where a specific ancestor
+   * can be passed.
+   * </li>
+   * </ul>
+   */
+  public static enum Feature implements LayoutFeature {
+    ROLLING_UPGRADE(-55, -53, "Support rolling upgrade", false);
+    
+    private final FeatureInfo info;
+
+    /**
+     * Feature that is added at layout version {@code lv} - 1. 
+     * @param lv new layout version with the addition of this feature
+     * @param description description of the feature
+     */
+    Feature(final int lv, final String description) {
+      this(lv, lv + 1, description, false);
+    }
+
+    /**
+     * NameNode feature that is added at layout version {@code ancestoryLV}.
+     * @param lv new layout version with the addition of this feature
+     * @param ancestorLV layout version from which the new lv is derived from.
+     * @param description description of the feature
+     * @param reserved true when this is a layout version reserved for previous
+     *        versions
+     * @param features set of features that are to be enabled for this version
+     */
+    Feature(final int lv, final int ancestorLV, final String description,
+        boolean reserved, Feature... features) {
+      info = new FeatureInfo(lv, ancestorLV, description, reserved, features);
+    }
+    
+    @Override
+    public FeatureInfo getInfo() {
+      return info;
+    }
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeMXBean.java

@@ -21,6 +21,7 @@ import java.util.Map;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeInfo;
 
 /**
  * This is the JMX management interface for namenode information
@@ -78,7 +79,14 @@ public interface NameNodeMXBean {
    * @return true, if upgrade is finalized
    */
   public boolean isUpgradeFinalized();
-  
+
+  /**
+   * Gets the RollingUpgrade information
+   *
+   * @return Rolling upgrade information
+   */
+  public RollingUpgradeInfo.Bean getRollingUpgradeStatus();
+
   /**
    * Gets total used space by data nodes for non DFS purposes such as storing
    * temporary files on the local file system

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java

@@ -37,6 +37,7 @@ import java.util.Set;
 import org.apache.commons.logging.Log;
 import org.apache.hadoop.HadoopIllegalArgumentException;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.BatchedRemoteIterator.BatchedEntries;
 import org.apache.hadoop.fs.CacheFlag;
 import org.apache.hadoop.fs.CommonConfigurationKeys;
 import org.apache.hadoop.fs.ContentSummary;
@@ -48,7 +49,6 @@ import org.apache.hadoop.fs.Options;
 import org.apache.hadoop.fs.ParentNotDirectoryException;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.UnresolvedLinkException;
-import org.apache.hadoop.fs.BatchedRemoteIterator.BatchedEntries;
 import org.apache.hadoop.fs.permission.AclEntry;
 import org.apache.hadoop.fs.permission.AclStatus;
 import org.apache.hadoop.fs.permission.FsPermission;
@@ -66,8 +66,8 @@ import org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException;
 import org.apache.hadoop.hdfs.protocol.BlockListAsLongs;
 import org.apache.hadoop.hdfs.protocol.CacheDirectiveEntry;
 import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
-import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
 import org.apache.hadoop.hdfs.protocol.CachePoolEntry;
+import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
 import org.apache.hadoop.hdfs.protocol.CorruptFileBlocks;
 import org.apache.hadoop.hdfs.protocol.DSQuotaExceededException;
 import org.apache.hadoop.hdfs.protocol.DatanodeID;
@@ -76,6 +76,7 @@ import org.apache.hadoop.hdfs.protocol.DirectoryListing;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.RollingUpgradeAction;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
@@ -83,6 +84,7 @@ import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
 import org.apache.hadoop.hdfs.protocol.NSQuotaExceededException;
 import org.apache.hadoop.hdfs.protocol.QuotaExceededException;
 import org.apache.hadoop.hdfs.protocol.RecoveryInProgressException;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeInfo;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
 import org.apache.hadoop.hdfs.protocol.UnregisteredNodeException;
@@ -102,6 +104,7 @@ import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifie
 import org.apache.hadoop.hdfs.server.blockmanagement.BlockManager;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NamenodeRole;
 import org.apache.hadoop.hdfs.server.common.IncorrectVersionException;
+import org.apache.hadoop.hdfs.server.datanode.DataNodeLayoutVersion;
 import org.apache.hadoop.hdfs.server.namenode.NameNode.OperationCategory;
 import org.apache.hadoop.hdfs.server.namenode.metrics.NameNodeMetrics;
 import org.apache.hadoop.hdfs.server.namenode.web.resources.NamenodeWebHdfsMethods;
@@ -873,6 +876,21 @@ class NameNodeRpcServer implements NamenodeProtocols {
     namesystem.finalizeUpgrade();
   }
 
+  @Override // ClientProtocol
+  public RollingUpgradeInfo rollingUpgrade(RollingUpgradeAction action) throws IOException {
+    LOG.info("rollingUpgrade " + action);
+    switch(action) {
+    case QUERY:
+      return namesystem.queryRollingUpgrade();
+    case PREPARE:
+      return namesystem.startRollingUpgrade();
+    case FINALIZE:
+      return namesystem.finalizeRollingUpgrade();
+    default:
+      throw new UnsupportedActionException(action + " is not yet supported.");
+    }
+  }
+
   @Override // ClientProtocol
   public void metaSave(String filename) throws IOException {
     namesystem.metaSave(filename);
@@ -971,7 +989,6 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // DatanodeProtocol
   public DatanodeRegistration registerDatanode(DatanodeRegistration nodeReg)
       throws IOException {
-    verifyLayoutVersion(nodeReg.getVersion());
     verifySoftwareVersion(nodeReg);
     namesystem.registerDatanode(nodeReg);
     return nodeReg;
@@ -1073,13 +1090,29 @@ class NameNodeRpcServer implements NamenodeProtocols {
    * @param nodeReg node registration
    * @throws UnregisteredNodeException if the registration is invalid
    */
-  void verifyRequest(NodeRegistration nodeReg) throws IOException {
-    verifyLayoutVersion(nodeReg.getVersion());
-    if (!namesystem.getRegistrationID().equals(nodeReg.getRegistrationID())) {
-      LOG.warn("Invalid registrationID - expected: "
-          + namesystem.getRegistrationID() + " received: "
-          + nodeReg.getRegistrationID());
-      throw new UnregisteredNodeException(nodeReg);
+  private void verifyRequest(NodeRegistration nodeReg) throws IOException {
+    // verify registration ID
+    final String id = nodeReg.getRegistrationID();
+    final String expectedID = namesystem.getRegistrationID();
+    if (!expectedID.equals(id)) {
+      LOG.warn("Registration IDs mismatched: the "
+          + nodeReg.getClass().getSimpleName() + " ID is " + id
+          + " but the expected ID is " + expectedID);
+       throw new UnregisteredNodeException(nodeReg);
+    }
+
+    // verify layout version if there is no rolling upgrade.
+    if (!namesystem.isRollingUpgrade()) {
+      final int lv = nodeReg.getVersion();
+      final int expectedLV = nodeReg instanceof NamenodeRegistration?
+          NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION
+          : DataNodeLayoutVersion.CURRENT_LAYOUT_VERSION;
+      if (expectedLV != nodeReg.getVersion()) {
+        LOG.warn("Layout versions mismatched: the "
+            + nodeReg.getClass().getSimpleName() + " LV is " + lv
+            + " but the expected LV is " + expectedLV);
+         throw new UnregisteredNodeException(nodeReg);
+      }
     }
   }
 
@@ -1161,8 +1194,9 @@ class NameNodeRpcServer implements NamenodeProtocols {
    * @throws IOException
    */
   void verifyLayoutVersion(int version) throws IOException {
-    if (version != HdfsConstants.LAYOUT_VERSION)
-      throw new IncorrectVersionException(version, "data node");
+    if (version != HdfsConstants.NAMENODE_LAYOUT_VERSION)
+      throw new IncorrectVersionException(
+          HdfsConstants.NAMENODE_LAYOUT_VERSION, version, "data node");
   }
   
   private void verifySoftwareVersion(DatanodeRegistration dnReg)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/SecondaryNameNode.java

@@ -445,8 +445,9 @@ public class SecondaryNameNode implements Runnable {
             } else {
               LOG.info("Image has changed. Downloading updated image from NN.");
               MD5Hash downloadedHash = TransferFsImage.downloadImageToStorage(
-                  nnHostPort, sig.mostRecentCheckpointTxId, dstImage.getStorage(), true);
-              dstImage.saveDigestAndRenameCheckpointImage(
+                  nnHostPort, sig.mostRecentCheckpointTxId,
+                  dstImage.getStorage(), true);
+              dstImage.saveDigestAndRenameCheckpointImage(NameNodeFile.IMAGE,
                   sig.mostRecentCheckpointTxId, downloadedHash);
             }
         
@@ -511,8 +512,10 @@ public class SecondaryNameNode implements Runnable {
     boolean loadImage = false;
     boolean isFreshCheckpointer = (checkpointImage.getNamespaceID() == 0);
     boolean isSameCluster =
-        (dstStorage.versionSupportsFederation() && sig.isSameCluster(checkpointImage)) ||
-        (!dstStorage.versionSupportsFederation() && sig.namespaceIdMatches(checkpointImage));
+        (dstStorage.versionSupportsFederation(NameNodeLayoutVersion.FEATURES)
+            && sig.isSameCluster(checkpointImage)) ||
+        (!dstStorage.versionSupportsFederation(NameNodeLayoutVersion.FEATURES)
+            && sig.namespaceIdMatches(checkpointImage));
     if (isFreshCheckpointer ||
         (isSameCluster &&
          !sig.storageVersionMatches(checkpointImage.getStorage()))) {
@@ -553,7 +556,7 @@ public class SecondaryNameNode implements Runnable {
     //
     long txid = checkpointImage.getLastAppliedTxId();
     TransferFsImage.uploadImageFromStorage(fsName, getImageListenAddress(),
-        dstStorage, txid);
+        dstStorage, NameNodeFile.IMAGE, txid);
 
     // error simulation code for junit test
     CheckpointFaultInjector.getInstance().afterSecondaryUploadsNewImage();
@@ -995,7 +998,8 @@ public class SecondaryNameNode implements Runnable {
     
     dstStorage.setStorageInfo(sig);
     if (loadImage) {
-      File file = dstStorage.findImageFile(sig.mostRecentCheckpointTxId);
+      File file = dstStorage.findImageFile(NameNodeFile.IMAGE,
+          sig.mostRecentCheckpointTxId);
       if (file == null) {
         throw new IOException("Couldn't find image file at txid " + 
             sig.mostRecentCheckpointTxId + " even though it should have " +

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/TransferFsImage.java

@@ -23,7 +23,6 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.net.HttpURLConnection;
-import java.net.InetSocketAddress;
 import java.net.URL;
 import java.security.DigestInputStream;
 import java.security.MessageDigest;
@@ -39,10 +38,6 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileUtil;
-import org.apache.hadoop.http.HttpConfig;
-import org.apache.hadoop.security.UserGroupInformation;
-import org.apache.hadoop.security.authentication.client.AuthenticationException;
-import org.apache.hadoop.util.Time;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
@@ -50,11 +45,13 @@ import org.apache.hadoop.hdfs.server.common.Storage;
 import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
 import org.apache.hadoop.hdfs.server.common.StorageErrorReporter;
 import org.apache.hadoop.hdfs.server.namenode.NNStorage.NameNodeDirType;
+import org.apache.hadoop.hdfs.server.namenode.NNStorage.NameNodeFile;
 import org.apache.hadoop.hdfs.server.protocol.RemoteEditLog;
 import org.apache.hadoop.hdfs.util.DataTransferThrottler;
 import org.apache.hadoop.hdfs.web.URLConnectionFactory;
 import org.apache.hadoop.io.MD5Hash;
-import org.apache.hadoop.security.SecurityUtil;
+import org.apache.hadoop.security.UserGroupInformation;
+import org.apache.hadoop.security.authentication.client.AuthenticationException;
 import org.apache.hadoop.util.Time;
 
 import com.google.common.annotations.VisibleForTesting;
@@ -90,10 +87,9 @@ public class TransferFsImage {
         null, false);
   }
 
-  public static MD5Hash downloadImageToStorage(
-      URL fsName, long imageTxId, Storage dstStorage, boolean needDigest)
-      throws IOException {
-    String fileid = GetImageServlet.getParamStringForImage(
+  public static MD5Hash downloadImageToStorage(URL fsName, long imageTxId,
+      Storage dstStorage, boolean needDigest) throws IOException {
+    String fileid = GetImageServlet.getParamStringForImage(null,
         imageTxId, dstStorage);
     String fileName = NNStorage.getCheckpointImageFileName(imageTxId);
     
@@ -166,14 +162,14 @@ public class TransferFsImage {
    * @param myNNAddress the host/port where the local node is running an
    *                           HTTPServer hosting GetImageServlet
    * @param storage the storage directory to transfer the image from
+   * @param nnf the NameNodeFile type of the image
    * @param txid the transaction ID of the image to be uploaded
    */
-  public static void uploadImageFromStorage(URL fsName,
-      URL myNNAddress,
-      Storage storage, long txid) throws IOException {
+  public static void uploadImageFromStorage(URL fsName, URL myNNAddress,
+      Storage storage, NameNodeFile nnf, long txid) throws IOException {
     
-    String fileid = GetImageServlet.getParamStringToPutImage(
-        txid, myNNAddress, storage);
+    String fileid = GetImageServlet.getParamStringToPutImage(nnf, txid,
+        myNNAddress, storage);
     // this doesn't directly upload an image, but rather asks the NN
     // to connect back to the 2NN to download the specified image.
     try {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/BootstrapStandby.java

@@ -46,6 +46,7 @@ import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
 import org.apache.hadoop.hdfs.server.namenode.NNStorage;
 import org.apache.hadoop.hdfs.server.namenode.NameNode;
 import org.apache.hadoop.hdfs.server.namenode.TransferFsImage;
+import org.apache.hadoop.hdfs.server.namenode.NNStorage.NameNodeFile;
 import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocol;
 import org.apache.hadoop.hdfs.server.protocol.NamespaceInfo;
 import org.apache.hadoop.hdfs.tools.DFSHAAdmin;
@@ -153,9 +154,9 @@ public class BootstrapStandby implements Tool, Configurable {
     }
 
     if (!checkLayoutVersion(nsInfo)) {
-      LOG.fatal("Layout version on remote node (" +
-          nsInfo.getLayoutVersion() + ") does not match " +
-          "this node's layout version (" + HdfsConstants.LAYOUT_VERSION + ")");
+      LOG.fatal("Layout version on remote node (" + nsInfo.getLayoutVersion()
+          + ") does not match " + "this node's layout version ("
+          + HdfsConstants.NAMENODE_LAYOUT_VERSION + ")");
       return ERR_CODE_INVALID_VERSION;
     }
 
@@ -207,9 +208,9 @@ public class BootstrapStandby implements Tool, Configurable {
 
       // Download that checkpoint into our storage directories.
       MD5Hash hash = TransferFsImage.downloadImageToStorage(
-        otherHttpAddr, imageTxId,
-        storage, true);
-      image.saveDigestAndRenameCheckpointImage(imageTxId, hash);
+        otherHttpAddr, imageTxId, storage, true);
+      image.saveDigestAndRenameCheckpointImage(NameNodeFile.IMAGE, imageTxId,
+          hash);
     } catch (IOException ioe) {
       image.close();
       throw ioe;
@@ -257,7 +258,7 @@ public class BootstrapStandby implements Tool, Configurable {
   }
 
   private boolean checkLayoutVersion(NamespaceInfo nsInfo) throws IOException {
-    return (nsInfo.getLayoutVersion() == HdfsConstants.LAYOUT_VERSION);
+    return (nsInfo.getLayoutVersion() == HdfsConstants.NAMENODE_LAYOUT_VERSION);
   }
   
   private void parseConfAndFindOtherNN() throws IOException {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/EditLogTailer.java

@@ -224,7 +224,7 @@ public class EditLogTailer {
       // disk are ignored.
       long editsLoaded = 0;
       try {
-        editsLoaded = image.loadEdits(streams, namesystem, null);
+        editsLoaded = image.loadEdits(streams, namesystem);
       } catch (EditLogInputException elie) {
         editsLoaded = elie.getNumEditsLoaded();
         throw elie;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/StandbyCheckpointer.java

@@ -40,6 +40,7 @@ import org.apache.hadoop.hdfs.HAUtil;
 import org.apache.hadoop.hdfs.server.namenode.CheckpointConf;
 import org.apache.hadoop.hdfs.server.namenode.FSImage;
 import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
+import org.apache.hadoop.hdfs.server.namenode.NNStorage.NameNodeFile;
 import org.apache.hadoop.hdfs.server.namenode.NameNode;
 import org.apache.hadoop.hdfs.server.namenode.SaveNamespaceCancelledException;
 import org.apache.hadoop.hdfs.server.namenode.TransferFsImage;
@@ -141,9 +142,14 @@ public class StandbyCheckpointer {
     }
   }
 
+  public void triggerRollbackCheckpoint() {
+    thread.interrupt();
+  }
+
   private void doCheckpoint() throws InterruptedException, IOException {
     assert canceler != null;
     final long txid;
+    final NameNodeFile imageType;
     
     namesystem.writeLockInterruptibly();
     try {
@@ -163,7 +169,15 @@ public class StandbyCheckpointer {
         return;
       }
 
-      img.saveNamespace(namesystem, canceler);
+      if (namesystem.isRollingUpgrade()
+          && !namesystem.getFSImage().hasRollbackFSImage()) {
+        // if we will do rolling upgrade but have not created the rollback image
+        // yet, name this checkpoint as fsimage_rollback
+        imageType = NameNodeFile.IMAGE_ROLLBACK;
+      } else {
+        imageType = NameNodeFile.IMAGE;
+      }
+      img.saveNamespace(namesystem, imageType, canceler);
       txid = img.getStorage().getMostRecentCheckpointTxId();
       assert txid == thisCheckpointTxId : "expected to save checkpoint at txid=" +
         thisCheckpointTxId + " but instead saved at txid=" + txid;
@@ -179,9 +193,8 @@ public class StandbyCheckpointer {
     Future<Void> upload = executor.submit(new Callable<Void>() {
       @Override
       public Void call() throws IOException {
-        TransferFsImage.uploadImageFromStorage(
-            activeNNAddress, myNNAddress,
-            namesystem.getFSImage().getStorage(), txid);
+        TransferFsImage.uploadImageFromStorage(activeNNAddress, myNNAddress,
+            namesystem.getFSImage().getStorage(), imageType, txid);
         return null;
       }
     });
@@ -266,16 +279,20 @@ public class StandbyCheckpointer {
     }
 
     private void doWork() {
+      final long checkPeriod = 1000 * checkpointConf.getCheckPeriod();
       // Reset checkpoint time so that we don't always checkpoint
       // on startup.
       lastCheckpointTime = now();
       while (shouldRun) {
-        try {
-          Thread.sleep(1000 * checkpointConf.getCheckPeriod());
-        } catch (InterruptedException ie) {
-        }
-        if (!shouldRun) {
-          break;
+        boolean needRollbackCheckpoint = namesystem.isNeedRollbackFsImage();
+        if (!needRollbackCheckpoint) {
+          try {
+            Thread.sleep(checkPeriod);
+          } catch (InterruptedException ie) {
+          }
+          if (!shouldRun) {
+            break;
+          }
         }
         try {
           // We may have lost our ticket since last checkpoint, log in again, just in case
@@ -287,8 +304,10 @@ public class StandbyCheckpointer {
           long uncheckpointed = countUncheckpointedTxns();
           long secsSinceLast = (now - lastCheckpointTime)/1000;
           
-          boolean needCheckpoint = false;
-          if (uncheckpointed >= checkpointConf.getTxnCount()) {
+          boolean needCheckpoint = needRollbackCheckpoint;
+          if (needCheckpoint) {
+            LOG.info("Triggering a rollback fsimage for rolling upgrade.");
+          } else if (uncheckpointed >= checkpointConf.getTxnCount()) {
             LOG.info("Triggering checkpoint because there have been " + 
                 uncheckpointed + " txns since the last checkpoint, which " +
                 "exceeds the configured threshold " +
@@ -313,6 +332,13 @@ public class StandbyCheckpointer {
           
           if (needCheckpoint) {
             doCheckpoint();
+            // reset needRollbackCheckpoint to false only when we finish a ckpt
+            // for rollback image
+            if (needRollbackCheckpoint
+                && namesystem.getFSImage().hasRollbackFSImage()) {
+              namesystem.setCreatedRollbackImages(true);
+              namesystem.setNeedRollbackFsImage(false);
+            }
             lastCheckpointTime = now;
           }
         } catch (SaveNamespaceCancelledException ce) {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/HeartbeatResponse.java

@@ -19,6 +19,7 @@ package org.apache.hadoop.hdfs.server.protocol;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeStatus;
 
 @InterfaceAudience.Private
 @InterfaceStability.Evolving
@@ -31,11 +32,14 @@ public class HeartbeatResponse {
   
   /** Information about the current HA-related state of the NN */
   private NNHAStatusHeartbeat haStatus;
+
+  private RollingUpgradeStatus rollingUpdateStatus;
   
   public HeartbeatResponse(DatanodeCommand[] cmds,
-      NNHAStatusHeartbeat haStatus) {
+      NNHAStatusHeartbeat haStatus, RollingUpgradeStatus rollingUpdateStatus) {
     commands = cmds;
     this.haStatus = haStatus;
+    this.rollingUpdateStatus = rollingUpdateStatus;
   }
   
   public DatanodeCommand[] getCommands() {
@@ -45,4 +49,8 @@ public class HeartbeatResponse {
   public NNHAStatusHeartbeat getNameNodeHaState() {
     return haStatus;
   }
+
+  public RollingUpgradeStatus getRollingUpdateStatus() {
+    return rollingUpdateStatus;
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/protocol/NamespaceInfo.java

@@ -25,6 +25,7 @@ import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.server.common.Storage;
 import org.apache.hadoop.hdfs.server.common.StorageInfo;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NodeType;
 import org.apache.hadoop.hdfs.server.namenode.NNStorage;
 import org.apache.hadoop.util.VersionInfo;
 
@@ -41,13 +42,14 @@ public class NamespaceInfo extends StorageInfo {
   String softwareVersion;
 
   public NamespaceInfo() {
-    super();
+    super(NodeType.NAME_NODE);
     buildVersion = null;
   }
 
   public NamespaceInfo(int nsID, String clusterID, String bpID,
       long cT, String buildVersion, String softwareVersion) {
-    super(HdfsConstants.LAYOUT_VERSION, nsID, clusterID, cT);
+    super(HdfsConstants.NAMENODE_LAYOUT_VERSION, nsID, clusterID, cT,
+        NodeType.NAME_NODE);
     blockPoolID = bpID;
     this.buildVersion = buildVersion;
     this.softwareVersion = softwareVersion;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/DFSAdmin.java

@@ -19,6 +19,7 @@ package org.apache.hadoop.hdfs.tools;
 
 import java.io.File;
 import java.io.IOException;
+import java.io.PrintStream;
 import java.net.InetSocketAddress;
 import java.net.URI;
 import java.net.URL;
@@ -49,9 +50,12 @@ import org.apache.hadoop.hdfs.NameNodeProxies;
 import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
 import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
+import org.apache.hadoop.hdfs.protocol.DatanodeLocalInfo;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.RollingUpgradeAction;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
+import org.apache.hadoop.hdfs.protocol.RollingUpgradeInfo;
 import org.apache.hadoop.hdfs.protocol.SnapshotException;
 import org.apache.hadoop.hdfs.server.namenode.NameNode;
 import org.apache.hadoop.hdfs.server.namenode.TransferFsImage;
@@ -66,6 +70,8 @@ import org.apache.hadoop.ipc.RefreshCallQueueProtocol;
 import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.util.ToolRunner;
 
+import com.google.common.base.Preconditions;
+
 /**
  * This class provides some DFS administrative access shell commands.
  */
@@ -273,7 +279,71 @@ public class DFSAdmin extends FsShell {
       dfs.setQuota(path, HdfsConstants.QUOTA_DONT_SET, quota);
     }
   }
-  
+
+  private static class RollingUpgradeCommand {
+    static final String NAME = "rollingUpgrade";
+    static final String USAGE = "-"+NAME+" [<query|prepare|finalize>]";
+    static final String DESCRIPTION = USAGE + ":\n"
+        + "     query: query the current rolling upgrade status.\n"
+        + "   prepare: prepare a new rolling upgrade."
+        + "  finalize: finalize the current rolling upgrade.";
+
+    /** Check if a command is the rollingUpgrade command
+     * 
+     * @param cmd A string representation of a command starting with "-"
+     * @return true if this is a clrQuota command; false otherwise
+     */
+    static boolean matches(String cmd) {
+      return ("-"+NAME).equals(cmd); 
+    }
+
+    private static void printMessage(RollingUpgradeInfo info,
+        PrintStream out) {
+      if (info != null && info.isStarted()) {
+        if (!info.createdRollbackImages()) {
+          out.println(
+              "Preparing for upgrade. Data is being saved for rollback."
+              + "\nRun \"dfsadmin -rollingUpgrade query\" to check the status"
+              + "\nfor proceeding with rolling upgrade");
+            out.println(info);
+        } else if (!info.isFinalized()) {
+          out.println("Proceed with rolling upgrade:");
+          out.println(info);
+        } else {
+          out.println("Rolling upgrade is finalized.");
+          out.println(info);
+        }
+      } else {
+        out.println("There is no rolling upgrade in progress.");
+      }
+    }
+
+    static int run(DistributedFileSystem dfs, String[] argv, int idx) throws IOException {
+      final RollingUpgradeAction action = RollingUpgradeAction.fromString(
+          argv.length >= 2? argv[1]: "");
+      if (action == null) {
+        throw new IllegalArgumentException("Failed to covert \"" + argv[1]
+            +"\" to " + RollingUpgradeAction.class.getSimpleName());
+      }
+
+      System.out.println(action + " rolling upgrade ...");
+
+      final RollingUpgradeInfo info = dfs.rollingUpgrade(action);
+      switch(action){
+      case QUERY:
+        break;
+      case PREPARE:
+        Preconditions.checkState(info.isStarted());
+        break;
+      case FINALIZE:
+        Preconditions.checkState(info.isFinalized());
+        break;
+      }
+      printMessage(info, System.out);
+      return 0;
+    }
+  }
+
   /**
    * Construct a DFSAdmin object.
    */
@@ -578,9 +648,11 @@ public class DFSAdmin extends FsShell {
       "\t[" + ClearQuotaCommand.USAGE +"]\n" +
       "\t[" + SetSpaceQuotaCommand.USAGE + "]\n" +
       "\t[" + ClearSpaceQuotaCommand.USAGE +"]\n" +
+      "\t[-finalizeUpgrade]\n" +
+      "\t[" + RollingUpgradeCommand.USAGE +"]\n" +
       "\t[-refreshServiceAcl]\n" +
       "\t[-refreshUserToGroupsMappings]\n" +
-      "\t[refreshSuperUserGroupsConfiguration]\n" +
+      "\t[-refreshSuperUserGroupsConfiguration]\n" +
       "\t[-refreshCallQueue]\n" +
       "\t[-printTopology]\n" +
       "\t[-refreshNamenodes datanodehost:port]\n"+
@@ -589,6 +661,8 @@ public class DFSAdmin extends FsShell {
       "\t[-fetchImage <local directory>]\n" +
       "\t[-allowSnapshot <snapshotDir>]\n" +
       "\t[-disallowSnapshot <snapshotDir>]\n" +
+      "\t[-shutdownDatanode <datanode_host:ipc_port> [upgrade]]\n" +
+      "\t[-getDatanodeInfo <datanode_host:ipc_port>\n" +
       "\t[-help [cmd]]\n";
 
     String report ="-report: \tReports basic filesystem information and statistics.\n";
@@ -687,6 +761,18 @@ public class DFSAdmin extends FsShell {
     
     String disallowSnapshot = "-disallowSnapshot <snapshotDir>:\n" +
         "\tDo not allow snapshots to be taken on a directory any more.\n";
+
+    String shutdownDatanode = "-shutdownDatanode <datanode_host:ipc_port> [upgrade]\n"
+        + "\tSubmit a shutdown request for the given datanode. If an optional\n"
+        + "\t\"upgrade\" argument is specified, clients accessing the datanode\n"
+        + "\twill be advised to wait for it to restart and the fast start-up\n"
+        + "\tmode will be enabled. When the restart does not happen in time,\n"
+        + "\tclients will timeout and ignore the datanode. In such case, the\n"
+        + "\tfast start-up mode will also be disabled.\n";
+
+    String getDatanodeInfo = "-getDatanodeInfo <datanode_host:ipc_port>\n"
+        + "\tGet the information about the given datanode. This command can\n"
+        + "\tbe used for checking if a datanode is alive.\n";
     
     String help = "-help [cmd]: \tDisplays help for the given command or all commands if none\n" +
       "\t\tis specified.\n";
@@ -705,6 +791,8 @@ public class DFSAdmin extends FsShell {
       System.out.println(refreshNodes);
     } else if ("finalizeUpgrade".equals(cmd)) {
       System.out.println(finalizeUpgrade);
+    } else if (RollingUpgradeCommand.matches("-"+cmd)) {
+      System.out.println(RollingUpgradeCommand.DESCRIPTION);
     } else if ("metasave".equals(cmd)) {
       System.out.println(metaSave);
     } else if (SetQuotaCommand.matches("-"+cmd)) {
@@ -737,6 +825,10 @@ public class DFSAdmin extends FsShell {
       System.out.println(allowSnapshot);
     } else if ("disallowSnapshot".equalsIgnoreCase(cmd)) {
       System.out.println(disallowSnapshot);
+    } else if ("shutdownDatanode".equalsIgnoreCase(cmd)) {
+      System.out.println(shutdownDatanode);
+    } else if ("getDatanodeInfo".equalsIgnoreCase(cmd)) {
+      System.out.println(getDatanodeInfo);
     } else if ("help".equals(cmd)) {
       System.out.println(help);
     } else {
@@ -748,6 +840,7 @@ public class DFSAdmin extends FsShell {
       System.out.println(restoreFailedStorage);
       System.out.println(refreshNodes);
       System.out.println(finalizeUpgrade);
+      System.out.println(RollingUpgradeCommand.DESCRIPTION);
       System.out.println(metaSave);
       System.out.println(SetQuotaCommand.DESCRIPTION);
       System.out.println(ClearQuotaCommand.DESCRIPTION);
@@ -764,6 +857,8 @@ public class DFSAdmin extends FsShell {
       System.out.println(fetchImage);
       System.out.println(allowSnapshot);
       System.out.println(disallowSnapshot);
+      System.out.println(shutdownDatanode);
+      System.out.println(getDatanodeInfo);
       System.out.println(help);
       System.out.println();
       ToolRunner.printGenericCommandUsage(System.out);
@@ -999,6 +1094,9 @@ public class DFSAdmin extends FsShell {
     } else if ("-finalizeUpgrade".equals(cmd)) {
       System.err.println("Usage: java DFSAdmin"
                          + " [-finalizeUpgrade]");
+    } else if (RollingUpgradeCommand.matches(cmd)) {
+      System.err.println("Usage: java DFSAdmin"
+          + " [" + RollingUpgradeCommand.USAGE+"]");
     } else if ("-metasave".equals(cmd)) {
       System.err.println("Usage: java DFSAdmin"
           + " [-metasave filename]");
@@ -1053,6 +1151,7 @@ public class DFSAdmin extends FsShell {
       System.err.println("           [-restoreFailedStorage true|false|check]");
       System.err.println("           [-refreshNodes]");
       System.err.println("           [-finalizeUpgrade]");
+      System.err.println("           ["+RollingUpgradeCommand.USAGE+"]");
       System.err.println("           [-metasave filename]");
       System.err.println("           [-refreshServiceAcl]");
       System.err.println("           [-refreshUserToGroupsMappings]");
@@ -1067,6 +1166,8 @@ public class DFSAdmin extends FsShell {
       System.err.println("           ["+ClearSpaceQuotaCommand.USAGE+"]");      
       System.err.println("           [-setBalancerBandwidth <bandwidth in bytes per second>]");
       System.err.println("           [-fetchImage <local directory>]");
+      System.err.println("           [-shutdownDatanode <datanode_host:ipc_port> [upgrade]]");
+      System.err.println("           [-getDatanodeInfo <datanode_host:ipc_port>]");
       System.err.println("           [-help [cmd]]");
       System.err.println();
       ToolRunner.printGenericCommandUsage(System.err);
@@ -1138,6 +1239,11 @@ public class DFSAdmin extends FsShell {
         printUsage(cmd);
         return exitCode;
       }
+    } else if (RollingUpgradeCommand.matches(cmd)) {
+      if (argv.length < 1 || argv.length > 2) {
+        printUsage(cmd);
+        return exitCode;
+      }
     } else if ("-metasave".equals(cmd)) {
       if (argv.length != 2) {
         printUsage(cmd);
@@ -1178,6 +1284,16 @@ public class DFSAdmin extends FsShell {
         printUsage(cmd);
         return exitCode;
       }
+    } else if ("-shutdownDatanode".equals(cmd)) {
+      if ((argv.length != 2) && (argv.length != 3)) {
+        printUsage(cmd);
+        return exitCode;
+      }
+    } else if ("-getDatanodeInfo".equals(cmd)) {
+      if (argv.length != 2) {
+        printUsage(cmd);
+        return exitCode;
+      }
     }
     
     // initialize DFSAdmin
@@ -1213,6 +1329,8 @@ public class DFSAdmin extends FsShell {
         exitCode = refreshNodes();
       } else if ("-finalizeUpgrade".equals(cmd)) {
         exitCode = finalizeUpgrade();
+      } else if (RollingUpgradeCommand.matches(cmd)) {
+        exitCode = RollingUpgradeCommand.run(getDFS(), argv, i);
       } else if ("-metasave".equals(cmd)) {
         exitCode = metaSave(argv, i);
       } else if (ClearQuotaCommand.matches(cmd)) {
@@ -1241,6 +1359,10 @@ public class DFSAdmin extends FsShell {
         exitCode = setBalancerBandwidth(argv, i);
       } else if ("-fetchImage".equals(cmd)) {
         exitCode = fetchImage(argv, i);
+      } else if ("-shutdownDatanode".equals(cmd)) {
+        exitCode = shutdownDatanode(argv, i);
+      } else if ("-getDatanodeInfo".equals(cmd)) {
+        exitCode = getDatanodeInfo(argv, i);
       } else if ("-help".equals(cmd)) {
         if (i < argv.length) {
           printHelp(argv[i]);
@@ -1325,6 +1447,35 @@ public class DFSAdmin extends FsShell {
     return 0;
   }
 
+  private int shutdownDatanode(String[] argv, int i) throws IOException {
+    final String dn = argv[i];
+    ClientDatanodeProtocol dnProxy = getDataNodeProxy(dn);
+    boolean upgrade = false;
+    if (argv.length-1 == i+1) {
+      if ("upgrade".equalsIgnoreCase(argv[i+1])) {
+        upgrade = true;
+      } else {
+        printUsage("-shutdownDatanode");
+        return -1;
+      }
+    }
+    dnProxy.shutdownDatanode(upgrade);
+    System.out.println("Submitted a shutdown request to datanode " + dn);
+    return 0;
+  }
+
+  private int getDatanodeInfo(String[] argv, int i) throws IOException {
+    ClientDatanodeProtocol dnProxy = getDataNodeProxy(argv[i]);
+    try {
+      DatanodeLocalInfo dnInfo = dnProxy.getDatanodeInfo();
+      System.out.println(dnInfo.getDatanodeLocalReport());
+    } catch (IOException ioe) {
+      System.err.println("Datanode unreachable.");
+      return -1;
+    }
+    return 0;
+  }
+
   /**
    * main() has some simple utility methods.
    * @param argv Command line parameters.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/ImageLoaderCurrent.java

@@ -30,10 +30,10 @@ import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo.AdminStates;
 import org.apache.hadoop.hdfs.protocol.LayoutFlags;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
-import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.hdfs.server.namenode.FSImageSerialization;
 import org.apache.hadoop.hdfs.server.namenode.INodeId;
+import org.apache.hadoop.hdfs.server.namenode.NameNodeLayoutVersion;
 import org.apache.hadoop.hdfs.tools.offlineImageViewer.ImageVisitor.ImageElement;
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.io.WritableUtils;
@@ -158,7 +158,8 @@ class ImageLoaderCurrent implements ImageLoader {
       imageVersion = in.readInt();
       if( !canLoadVersion(imageVersion))
         throw new IOException("Cannot process fslayout version " + imageVersion);
-      if (LayoutVersion.supports(Feature.ADD_LAYOUT_FLAGS, imageVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.ADD_LAYOUT_FLAGS, imageVersion)) {
         LayoutFlags.read(in);
       }
 
@@ -169,22 +170,25 @@ class ImageLoaderCurrent implements ImageLoader {
 
       v.visit(ImageElement.GENERATION_STAMP, in.readLong());
 
-      if (LayoutVersion.supports(Feature.SEQUENTIAL_BLOCK_ID, imageVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.SEQUENTIAL_BLOCK_ID, imageVersion)) {
         v.visit(ImageElement.GENERATION_STAMP_V2, in.readLong());
         v.visit(ImageElement.GENERATION_STAMP_V1_LIMIT, in.readLong());
         v.visit(ImageElement.LAST_ALLOCATED_BLOCK_ID, in.readLong());
       }
 
-      if (LayoutVersion.supports(Feature.STORED_TXIDS, imageVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.STORED_TXIDS, imageVersion)) {
         v.visit(ImageElement.TRANSACTION_ID, in.readLong());
       }
       
-      if (LayoutVersion.supports(Feature.ADD_INODE_ID, imageVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.ADD_INODE_ID, imageVersion)) {
         v.visit(ImageElement.LAST_INODE_ID, in.readLong());
       }
       
-      boolean supportSnapshot = LayoutVersion.supports(Feature.SNAPSHOT,
-          imageVersion);
+      boolean supportSnapshot = NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.SNAPSHOT, imageVersion);
       if (supportSnapshot) {
         v.visit(ImageElement.SNAPSHOT_COUNTER, in.readInt());
         int numSnapshots = in.readInt();
@@ -194,7 +198,8 @@ class ImageLoaderCurrent implements ImageLoader {
         }
       }
       
-      if (LayoutVersion.supports(Feature.FSIMAGE_COMPRESSION, imageVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.FSIMAGE_COMPRESSION, imageVersion)) {
         boolean isCompressed = in.readBoolean();
         v.visit(ImageElement.IS_COMPRESSED, String.valueOf(isCompressed));
         if (isCompressed) {
@@ -216,11 +221,13 @@ class ImageLoaderCurrent implements ImageLoader {
 
       processINodesUC(in, v, skipBlocks);
 
-      if (LayoutVersion.supports(Feature.DELEGATION_TOKEN, imageVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.DELEGATION_TOKEN, imageVersion)) {
         processDelegationTokens(in, v);
       }
       
-      if (LayoutVersion.supports(Feature.CACHING, imageVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.CACHING, imageVersion)) {
         processCacheManagerState(in, v);
       }
       v.leaveEnclosingElement(); // FSImage
@@ -323,7 +330,8 @@ class ImageLoaderCurrent implements ImageLoader {
       String n = new String(name, "UTF8");
       v.visit(ImageElement.INODE_PATH, n);
       
-      if (LayoutVersion.supports(Feature.ADD_INODE_ID, imageVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.ADD_INODE_ID, imageVersion)) {
         long inodeId = in.readLong();
         v.visit(ImageElement.INODE_ID, inodeId);
       }
@@ -443,7 +451,8 @@ class ImageLoaderCurrent implements ImageLoader {
     v.visitEnclosingElement(ImageElement.INODES,
         ImageElement.NUM_INODES, numInodes);
     
-    if (LayoutVersion.supports(Feature.FSIMAGE_NAME_OPTIMIZATION, imageVersion)) {
+    if (NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.FSIMAGE_NAME_OPTIMIZATION, imageVersion)) {
       if (!supportSnapshot) {
         processLocalNameINodes(in, v, numInodes, skipBlocks);
       } else {
@@ -584,7 +593,8 @@ class ImageLoaderCurrent implements ImageLoader {
     if (!useRoot) {
       if (in.readBoolean()) {
         v.visitEnclosingElement(ImageElement.SNAPSHOT_INODE_DIRECTORY_ATTRIBUTES);
-        if (LayoutVersion.supports(Feature.OPTIMIZE_SNAPSHOT_INODES, imageVersion)) {
+        if (NameNodeLayoutVersion.supports(
+            LayoutVersion.Feature.OPTIMIZE_SNAPSHOT_INODES, imageVersion)) {
           processINodeDirectoryAttributes(in, v, currentINodeName);
         } else {
           processINode(in, v, true, currentINodeName, true);
@@ -678,10 +688,10 @@ class ImageLoaderCurrent implements ImageLoader {
   private void processINode(DataInputStream in, ImageVisitor v,
       boolean skipBlocks, String parentName, boolean isSnapshotCopy)
       throws IOException {
-    boolean supportSnapshot = 
-        LayoutVersion.supports(Feature.SNAPSHOT, imageVersion);
-    boolean supportInodeId = 
-        LayoutVersion.supports(Feature.ADD_INODE_ID, imageVersion);
+    boolean supportSnapshot = NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.SNAPSHOT, imageVersion);
+    boolean supportInodeId = NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.ADD_INODE_ID, imageVersion);
     
     v.visitEnclosingElement(ImageElement.INODE);
     final String pathName = readINodePath(in, parentName);
@@ -694,7 +704,8 @@ class ImageLoaderCurrent implements ImageLoader {
     }
     v.visit(ImageElement.REPLICATION, in.readShort());
     v.visit(ImageElement.MODIFICATION_TIME, formatDate(in.readLong()));
-    if(LayoutVersion.supports(Feature.FILE_ACCESS_TIME, imageVersion))
+    if(NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.FILE_ACCESS_TIME, imageVersion))
       v.visit(ImageElement.ACCESS_TIME, formatDate(in.readLong()));
     v.visit(ImageElement.BLOCK_SIZE, in.readLong());
     int numBlocks = in.readInt();
@@ -723,7 +734,8 @@ class ImageLoaderCurrent implements ImageLoader {
         dirNodeMap.put(inodeId, pathName);
       }
       v.visit(ImageElement.NS_QUOTA, numBlocks == -1 ? in.readLong() : -1);
-      if (LayoutVersion.supports(Feature.DISKSPACE_QUOTA, imageVersion))
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.DISKSPACE_QUOTA, imageVersion))
         v.visit(ImageElement.DS_QUOTA, numBlocks == -1 ? in.readLong() : -1);
       if (supportSnapshot) {
         boolean snapshottable = in.readBoolean();
@@ -771,7 +783,8 @@ class ImageLoaderCurrent implements ImageLoader {
     v.visit(ImageElement.INODE_PATH, pathName);
     processPermission(in, v);
     v.visit(ImageElement.MODIFICATION_TIME, formatDate(in.readLong()));
-    if(LayoutVersion.supports(Feature.FILE_ACCESS_TIME, imageVersion)) {
+    if(NameNodeLayoutVersion.supports(
+        LayoutVersion.Feature.FILE_ACCESS_TIME, imageVersion)) {
       v.visit(ImageElement.ACCESS_TIME, formatDate(in.readLong()));
     }
 
@@ -800,7 +813,8 @@ class ImageLoaderCurrent implements ImageLoader {
     v.visit(ImageElement.SNAPSHOT_FILE_SIZE, in.readLong());
     if (in.readBoolean()) {
       v.visitEnclosingElement(ImageElement.SNAPSHOT_INODE_FILE_ATTRIBUTES);
-      if (LayoutVersion.supports(Feature.OPTIMIZE_SNAPSHOT_INODES, imageVersion)) {
+      if (NameNodeLayoutVersion.supports(
+          LayoutVersion.Feature.OPTIMIZE_SNAPSHOT_INODES, imageVersion)) {
         processINodeFileAttributes(in, v, currentINodeName);
       } else {
         processINode(in, v, true, currentINodeName, true);

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/util/MD5FileUtils.java

@@ -20,6 +20,7 @@ package org.apache.hadoop.hdfs.util;
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileInputStream;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
@@ -65,23 +66,17 @@ public abstract class MD5FileUtils {
   }
   
   /**
-   * Read the md5 checksum stored alongside the given file, or null
-   * if no md5 is stored.
+   * Read the md5 file stored alongside the given data file
+   * and match the md5 file content.
    * @param dataFile the file containing data
-   * @return the checksum stored in dataFile.md5
+   * @return a matcher with two matched groups
+   *   where group(1) is the md5 string and group(2) is the data file path.
    */
-  public static MD5Hash readStoredMd5ForFile(File dataFile) throws IOException {
-    File md5File = getDigestFileForFile(dataFile);
-
-    String md5Line;
-    
-    if (!md5File.exists()) {
-      return null;
-    }
-    
+  private static Matcher readStoredMd5(File md5File) throws IOException {
     BufferedReader reader =
         new BufferedReader(new InputStreamReader(new FileInputStream(
             md5File), Charsets.UTF_8));
+    String md5Line;
     try {
       md5Line = reader.readLine();
       if (md5Line == null) { md5Line = ""; }
@@ -94,9 +89,24 @@ public abstract class MD5FileUtils {
     
     Matcher matcher = LINE_REGEX.matcher(md5Line);
     if (!matcher.matches()) {
-      throw new IOException("Invalid MD5 file at " + md5File
-          + " (does not match expected pattern)");
+      throw new IOException("Invalid MD5 file " + md5File + ": the content \""
+          + md5Line + "\" does not match the expected pattern.");
+    }
+    return matcher;
+  }
+
+  /**
+   * Read the md5 checksum stored alongside the given data file.
+   * @param dataFile the file containing data
+   * @return the checksum stored in dataFile.md5
+   */
+  public static MD5Hash readStoredMd5ForFile(File dataFile) throws IOException {
+    final File md5File = getDigestFileForFile(dataFile);
+    if (!md5File.exists()) {
+      return null;
     }
+
+    final Matcher matcher = readStoredMd5(md5File);
     String storedHash = matcher.group(1);
     File referencedFile = new File(matcher.group(2));
 
@@ -135,15 +145,37 @@ public abstract class MD5FileUtils {
    */
   public static void saveMD5File(File dataFile, MD5Hash digest)
       throws IOException {
+    final String digestString = StringUtils.byteToHexString(digest.getDigest());
+    saveMD5File(dataFile, digestString);
+  }
+
+  private static void saveMD5File(File dataFile, String digestString)
+      throws IOException {
     File md5File = getDigestFileForFile(dataFile);
-    String digestString = StringUtils.byteToHexString(
-        digest.getDigest());
     String md5Line = digestString + " *" + dataFile.getName() + "\n";
-    
+
     AtomicFileOutputStream afos = new AtomicFileOutputStream(md5File);
     afos.write(md5Line.getBytes(Charsets.UTF_8));
     afos.close();
-    LOG.debug("Saved MD5 " + digest + " to " + md5File);
+
+    if (LOG.isDebugEnabled()) {
+      LOG.debug("Saved MD5 " + digestString + " to " + md5File);
+    }
+  }
+
+  public static void renameMD5File(File oldDataFile, File newDataFile)
+      throws IOException {
+    final File fromFile = getDigestFileForFile(oldDataFile);
+    if (!fromFile.exists()) {
+      throw new FileNotFoundException(fromFile + " does not exist.");
+    }
+
+    final String digestString = readStoredMd5(fromFile).group(1);
+    saveMD5File(newDataFile, digestString);
+
+    if (!fromFile.delete()) {
+      LOG.warn("deleting  " + fromFile.getAbsolutePath() + " FAILED");
+    }
   }
 
   /**

hadoop-hdfs-project/hadoop-hdfs/src/main/proto/ClientDatanodeProtocol.proto

@@ -127,6 +127,28 @@ message GetHdfsBlockLocationsResponseProto {
   repeated uint32 volumeIndexes = 2 [ packed = true ];
 }
 
+/**
+ * forUpgrade - if true, clients are advised to wait for restart and quick
+ *              upgrade restart is instrumented. Otherwise, datanode does
+ *              the regular shutdown.
+ */
+message ShutdownDatanodeRequestProto {
+  required bool forUpgrade = 1;
+}
+
+message ShutdownDatanodeResponseProto {
+}
+
+/**
+ * Ping datanode for liveness and quick info
+ */
+message GetDatanodeInfoRequestProto {
+}
+
+message GetDatanodeInfoResponseProto {
+  required DatanodeLocalInfoProto localInfo = 1;
+}
+
 /**
  * Protocol used from client to the Datanode.
  * See the request and response for details of rpc call.
@@ -164,4 +186,10 @@ service ClientDatanodeProtocolService {
    */
   rpc getHdfsBlockLocations(GetHdfsBlockLocationsRequestProto)
       returns(GetHdfsBlockLocationsResponseProto);
+
+  rpc shutdownDatanode(ShutdownDatanodeRequestProto)
+      returns(ShutdownDatanodeResponseProto);
+
+  rpc getDatanodeInfo(GetDatanodeInfoRequestProto)
+      returns(GetDatanodeInfoResponseProto);
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/proto/ClientNamenodeProtocol.proto

@@ -333,6 +333,27 @@ message FinalizeUpgradeRequestProto { // no parameters
 message FinalizeUpgradeResponseProto { // void response
 }
 
+enum RollingUpgradeActionProto {
+  QUERY = 1;
+  START = 2;
+  FINALIZE = 3;
+}
+
+message RollingUpgradeRequestProto {
+  required RollingUpgradeActionProto action = 1;
+}
+
+message RollingUpgradeInfoProto {
+  required RollingUpgradeStatusProto status = 1;
+  required uint64 startTime = 2;
+  required uint64 finalizeTime = 3;
+  required bool createdRollbackImages = 4;
+}
+
+message RollingUpgradeResponseProto {
+  optional RollingUpgradeInfoProto rollingUpgradeInfo= 1;
+}
+
 message ListCorruptFileBlocksRequestProto {
   required string path = 1;
   optional string cookie = 2;
@@ -659,6 +680,8 @@ service ClientNamenodeProtocol {
   rpc refreshNodes(RefreshNodesRequestProto) returns(RefreshNodesResponseProto);
   rpc finalizeUpgrade(FinalizeUpgradeRequestProto)
       returns(FinalizeUpgradeResponseProto);
+  rpc rollingUpgrade(RollingUpgradeRequestProto)
+      returns(RollingUpgradeResponseProto);
   rpc listCorruptFileBlocks(ListCorruptFileBlocksRequestProto)
       returns(ListCorruptFileBlocksResponseProto);
   rpc metaSave(MetaSaveRequestProto) returns(MetaSaveResponseProto);

hadoop-hdfs-project/hadoop-hdfs/src/main/proto/DatanodeProtocol.proto

@@ -221,6 +221,7 @@ message NNHAStatusHeartbeatProto {
 message HeartbeatResponseProto {
   repeated DatanodeCommandProto cmds = 1; // Returned commands can be null
   required NNHAStatusHeartbeatProto haStatus = 2;
+  optional RollingUpgradeStatusProto rollingUpgradeStatus = 3;
 }
 
 /**

hadoop-hdfs-project/hadoop-hdfs/src/main/proto/QJournalProtocol.proto

@@ -199,6 +199,17 @@ message DoRollbackRequestProto {
 message DoRollbackResponseProto {
 }
 
+/**
+ * discardSegments()
+ */
+message DiscardSegmentsRequestProto {
+  required JournalIdProto jid = 1;
+  required uint64 startTxId = 2;
+}
+
+message DiscardSegmentsResponseProto {
+}
+
 /**
  * getJournalState()
  */
@@ -314,6 +325,8 @@ service QJournalProtocolService {
 
   rpc doRollback(DoRollbackRequestProto) returns (DoRollbackResponseProto);
 
+  rpc discardSegments(DiscardSegmentsRequestProto) returns (DiscardSegmentsResponseProto);
+
   rpc getJournalState(GetJournalStateRequestProto) returns (GetJournalStateResponseProto);
 
   rpc newEpoch(NewEpochRequestProto) returns (NewEpochResponseProto);

hadoop-hdfs-project/hadoop-hdfs/src/main/proto/datatransfer.proto

@@ -199,6 +199,10 @@ enum Status {
   ERROR_ACCESS_TOKEN = 5;
   CHECKSUM_OK = 6;
   ERROR_UNSUPPORTED = 7;
+  OOB_RESTART = 8;            // Quick restart
+  OOB_RESERVED1 = 9;          // Reserved
+  OOB_RESERVED2 = 10;         // Reserved
+  OOB_RESERVED3 = 11;         // Reserved
 }
 
 message PipelineAckProto {

hadoop-hdfs-project/hadoop-hdfs/src/main/proto/fsimage.proto

@@ -71,6 +71,7 @@ message NameSystemSection {
   optional uint64 genstampV1Limit = 4;
   optional uint64 lastAllocatedBlockId = 5;
   optional uint64 transactionId = 6;
+  optional uint64 rollingUpgradeStartTime = 7;
 }
 
 /**

hadoop-hdfs-project/hadoop-hdfs/src/main/proto/hdfs.proto

@@ -60,6 +60,15 @@ message DatanodeIDProto {
   optional uint32 infoSecurePort = 7 [default = 0]; // datanode https port
 }
 
+/**
+ * Datanode local information
+ */
+message DatanodeLocalInfoProto {
+  required string softwareVersion = 1;
+  required string configVersion = 2;
+  required uint64 uptime = 3;
+}
+
 /**
  * DatanodeInfo array
  */
@@ -459,4 +468,9 @@ message SnapshotInfoProto {
   // TODO: do we need access time?
 }
 
-
+/**
+ * Rolling upgrade status
+ */
+message RollingUpgradeStatusProto {
+  required string blockPoolId = 1;
+}