HDFS-3443. Fix NPE when namenode transition to active during startup by adding checkNNStartup() in NameNodeRpcServer. Contributed by Vinayakumar B

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

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

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

@@ -27,6 +27,9 @@ Release 2.6.1 - UNRELEASED
     HDFS-7443. Datanode upgrade to BLOCKID_BASED_LAYOUT fails if duplicate
     block files are present in the same volume (cmccabe)
 
+    HDFS-3443. Fix NPE when namenode transition to active during startup by
+    adding checkNNStartup() in NameNodeRpcServer.  (Vinayakumar B via szetszwo)
+
 Release 2.6.0 - 2014-11-18
 
   INCOMPATIBLE CHANGES

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

@@ -78,6 +78,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.FS_DEFAULT_NAME_KEY;
 import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.FS_TRASH_INTERVAL_DEFAULT;
@@ -264,6 +265,7 @@ public class NameNode implements NameNodeStatusMXBean {
   private final boolean haEnabled;
   private final HAContext haContext;
   protected final boolean allowStaleStandbyReads;
+  private AtomicBoolean started = new AtomicBoolean(false); 
 
   
   /** httpServer */
@@ -774,6 +776,7 @@ public class NameNode implements NameNodeStatusMXBean {
       this.stop();
       throw e;
     }
+    this.started.set(true);
   }
 
   protected HAState createHAState(StartupOption startOpt) {
@@ -1733,7 +1736,14 @@ public class NameNode implements NameNodeStatusMXBean {
   public boolean isActiveState() {
     return (state.equals(ACTIVE_STATE));
   }
-  
+
+  /**
+   * Returns whether the NameNode is completely started
+   */
+  boolean isStarted() {
+    return this.started.get();
+  }
+
   /**
    * Check that a request to change this node's HA state is valid.
    * In particular, verifies that, if auto failover is enabled, non-forced

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

@@ -465,12 +465,14 @@ class NameNodeRpcServer implements NamenodeProtocols {
       throw new IllegalArgumentException(
         "Unexpected not positive size: "+size);
     }
+    checkNNStartup();
     namesystem.checkSuperuserPrivilege();
     return namesystem.getBlockManager().getBlocks(datanode, size); 
   }
 
   @Override // NamenodeProtocol
   public ExportedBlockKeys getBlockKeys() throws IOException {
+    checkNNStartup();
     namesystem.checkSuperuserPrivilege();
     return namesystem.getBlockManager().getBlockKeys();
   }
@@ -479,6 +481,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   public void errorReport(NamenodeRegistration registration,
                           int errorCode, 
                           String msg) throws IOException {
+    checkNNStartup();
     namesystem.checkOperation(OperationCategory.UNCHECKED);
     namesystem.checkSuperuserPrivilege();
     verifyRequest(registration);
@@ -491,6 +494,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // NamenodeProtocol
   public NamenodeRegistration registerSubordinateNamenode(
       NamenodeRegistration registration) throws IOException {
+    checkNNStartup();
     namesystem.checkSuperuserPrivilege();
     verifyLayoutVersion(registration.getVersion());
     NamenodeRegistration myRegistration = nn.setRegistration();
@@ -500,7 +504,8 @@ class NameNodeRpcServer implements NamenodeProtocols {
 
   @Override // NamenodeProtocol
   public NamenodeCommand startCheckpoint(NamenodeRegistration registration)
-  throws IOException {
+      throws IOException {
+    checkNNStartup();
     namesystem.checkSuperuserPrivilege();
     verifyRequest(registration);
     if(!nn.isRole(NamenodeRole.NAMENODE))
@@ -511,6 +516,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // NamenodeProtocol
   public void endCheckpoint(NamenodeRegistration registration,
                             CheckpointSignature sig) throws IOException {
+    checkNNStartup();
     namesystem.checkSuperuserPrivilege();
     namesystem.endCheckpoint(registration, sig);
   }
@@ -518,18 +524,21 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // ClientProtocol
   public Token<DelegationTokenIdentifier> getDelegationToken(Text renewer)
       throws IOException {
+    checkNNStartup();
     return namesystem.getDelegationToken(renewer);
   }
 
   @Override // ClientProtocol
   public long renewDelegationToken(Token<DelegationTokenIdentifier> token)
       throws InvalidToken, IOException {
+    checkNNStartup();
     return namesystem.renewDelegationToken(token);
   }
 
   @Override // ClientProtocol
   public void cancelDelegationToken(Token<DelegationTokenIdentifier> token)
       throws IOException {
+    checkNNStartup();
     namesystem.cancelDelegationToken(token);
   }
   
@@ -538,6 +547,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
                                           long offset, 
                                           long length) 
       throws IOException {
+    checkNNStartup();
     metrics.incrGetBlockLocations();
     return namesystem.getBlockLocations(getClientMachine(), 
                                         src, offset, length);
@@ -545,6 +555,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   
   @Override // ClientProtocol
   public FsServerDefaults getServerDefaults() throws IOException {
+    checkNNStartup();
     return namesystem.getServerDefaults();
   }
 
@@ -554,6 +565,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
       boolean createParent, short replication, long blockSize, 
       CryptoProtocolVersion[] supportedVersions)
       throws IOException {
+    checkNNStartup();
     String clientMachine = getClientMachine();
     if (stateChangeLog.isDebugEnabled()) {
       stateChangeLog.debug("*DIR* NameNode.create: file "
@@ -575,6 +587,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // ClientProtocol
   public LocatedBlock append(String src, String clientName) 
       throws IOException {
+    checkNNStartup();
     String clientMachine = getClientMachine();
     if (stateChangeLog.isDebugEnabled()) {
       stateChangeLog.debug("*DIR* NameNode.append: file "
@@ -587,36 +600,42 @@ class NameNodeRpcServer implements NamenodeProtocols {
 
   @Override // ClientProtocol
   public boolean recoverLease(String src, String clientName) throws IOException {
+    checkNNStartup();
     String clientMachine = getClientMachine();
     return namesystem.recoverLease(src, clientName, clientMachine);
   }
 
   @Override // ClientProtocol
   public boolean setReplication(String src, short replication) 
-    throws IOException {  
+    throws IOException {
+    checkNNStartup();
     return namesystem.setReplication(src, replication);
   }
 
   @Override
   public void setStoragePolicy(String src, String policyName)
       throws IOException {
+    checkNNStartup();
     namesystem.setStoragePolicy(src, policyName);
   }
 
   @Override
   public BlockStoragePolicy[] getStoragePolicies() throws IOException {
+    checkNNStartup();
     return namesystem.getStoragePolicies();
   }
 
   @Override // ClientProtocol
   public void setPermission(String src, FsPermission permissions)
       throws IOException {
+    checkNNStartup();
     namesystem.setPermission(src, permissions);
   }
 
   @Override // ClientProtocol
   public void setOwner(String src, String username, String groupname)
       throws IOException {
+    checkNNStartup();
     namesystem.setOwner(src, username, groupname);
   }
   
@@ -625,6 +644,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
       ExtendedBlock previous, DatanodeInfo[] excludedNodes, long fileId,
       String[] favoredNodes)
       throws IOException {
+    checkNNStartup();
     if (stateChangeLog.isDebugEnabled()) {
       stateChangeLog.debug("*BLOCK* NameNode.addBlock: file " + src
           + " fileId=" + fileId + " for " + clientName);
@@ -652,6 +672,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
       final DatanodeInfo[] excludes,
       final int numAdditionalNodes, final String clientName
       ) throws IOException {
+    checkNNStartup();
     if (LOG.isDebugEnabled()) {
       LOG.debug("getAdditionalDatanode: src=" + src
           + ", fileId=" + fileId
@@ -680,6 +701,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // ClientProtocol
   public void abandonBlock(ExtendedBlock b, long fileId, String src,
         String holder) throws IOException {
+    checkNNStartup();
     if(stateChangeLog.isDebugEnabled()) {
       stateChangeLog.debug("*BLOCK* NameNode.abandonBlock: "
           +b+" of file "+src);
@@ -693,6 +715,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   public boolean complete(String src, String clientName,
                           ExtendedBlock last,  long fileId)
       throws IOException {
+    checkNNStartup();
     if(stateChangeLog.isDebugEnabled()) {
       stateChangeLog.debug("*DIR* NameNode.complete: "
           + src + " fileId=" + fileId +" for " + clientName);
@@ -708,12 +731,14 @@ class NameNodeRpcServer implements NamenodeProtocols {
    */
   @Override // ClientProtocol, DatanodeProtocol
   public void reportBadBlocks(LocatedBlock[] blocks) throws IOException {
+    checkNNStartup();
     namesystem.reportBadBlocks(blocks);
   }
 
   @Override // ClientProtocol
   public LocatedBlock updateBlockForPipeline(ExtendedBlock block, String clientName)
       throws IOException {
+    checkNNStartup();
     return namesystem.updateBlockForPipeline(block, clientName);
   }
 
@@ -722,6 +747,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   public void updatePipeline(String clientName, ExtendedBlock oldBlock,
       ExtendedBlock newBlock, DatanodeID[] newNodes, String[] newStorageIDs)
       throws IOException {
+    checkNNStartup();
     namesystem.updatePipeline(clientName, oldBlock, newBlock, newNodes, newStorageIDs);
   }
   
@@ -731,6 +757,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
       boolean closeFile, boolean deleteblock, DatanodeID[] newtargets,
       String[] newtargetstorages)
       throws IOException {
+    checkNNStartup();
     namesystem.commitBlockSynchronization(block, newgenerationstamp,
         newlength, closeFile, deleteblock, newtargets, newtargetstorages);
   }
@@ -738,12 +765,14 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // ClientProtocol
   public long getPreferredBlockSize(String filename) 
       throws IOException {
+    checkNNStartup();
     return namesystem.getPreferredBlockSize(filename);
   }
     
   @Deprecated
   @Override // ClientProtocol
   public boolean rename(String src, String dst) throws IOException {
+    checkNNStartup();
     if(stateChangeLog.isDebugEnabled()) {
       stateChangeLog.debug("*DIR* NameNode.rename: " + src + " to " + dst);
     }
@@ -760,12 +789,14 @@ class NameNodeRpcServer implements NamenodeProtocols {
   
   @Override // ClientProtocol
   public void concat(String trg, String[] src) throws IOException {
+    checkNNStartup();
     namesystem.concat(trg, src);
   }
   
   @Override // ClientProtocol
   public void rename2(String src, String dst, Options.Rename... options)
       throws IOException {
+    checkNNStartup();
     if(stateChangeLog.isDebugEnabled()) {
       stateChangeLog.debug("*DIR* NameNode.rename: " + src + " to " + dst);
     }
@@ -779,6 +810,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
 
   @Override // ClientProtocol
   public boolean delete(String src, boolean recursive) throws IOException {
+    checkNNStartup();
     if (stateChangeLog.isDebugEnabled()) {
       stateChangeLog.debug("*DIR* Namenode.delete: src=" + src
           + ", recursive=" + recursive);
@@ -803,6 +835,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // ClientProtocol
   public boolean mkdirs(String src, FsPermission masked, boolean createParent)
       throws IOException {
+    checkNNStartup();
     if(stateChangeLog.isDebugEnabled()) {
       stateChangeLog.debug("*DIR* NameNode.mkdirs: " + src);
     }
@@ -817,12 +850,14 @@ class NameNodeRpcServer implements NamenodeProtocols {
 
   @Override // ClientProtocol
   public void renewLease(String clientName) throws IOException {
+    checkNNStartup();
     namesystem.renewLease(clientName);        
   }
 
   @Override // ClientProtocol
   public DirectoryListing getListing(String src, byte[] startAfter,
       boolean needLocation) throws IOException {
+    checkNNStartup();
     DirectoryListing files = namesystem.getListing(
         src, startAfter, needLocation);
     if (files != null) {
@@ -834,23 +869,27 @@ class NameNodeRpcServer implements NamenodeProtocols {
 
   @Override // ClientProtocol
   public HdfsFileStatus getFileInfo(String src)  throws IOException {
+    checkNNStartup();
     metrics.incrFileInfoOps();
     return namesystem.getFileInfo(src, true);
   }
   
   @Override // ClientProtocol
   public boolean isFileClosed(String src) throws IOException{
+    checkNNStartup();
     return namesystem.isFileClosed(src);
   }
   
   @Override // ClientProtocol
-  public HdfsFileStatus getFileLinkInfo(String src) throws IOException { 
+  public HdfsFileStatus getFileLinkInfo(String src) throws IOException {
+    checkNNStartup();
     metrics.incrFileInfoOps();
     return namesystem.getFileInfo(src, false);
   }
   
   @Override // ClientProtocol
   public long[] getStats() throws IOException {
+    checkNNStartup();
     namesystem.checkOperation(OperationCategory.READ);
     return namesystem.getStats();
   }
@@ -858,6 +897,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // ClientProtocol
   public DatanodeInfo[] getDatanodeReport(DatanodeReportType type)
   throws IOException {
+    checkNNStartup();
     DatanodeInfo results[] = namesystem.datanodeReport(type);
     if (results == null ) {
       throw new IOException("Failed to get datanode report for " + type
@@ -869,6 +909,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // ClientProtocol
   public DatanodeStorageReport[] getDatanodeStorageReport(
       DatanodeReportType type) throws IOException {
+    checkNNStartup();
     final DatanodeStorageReport[] reports = namesystem.getDatanodeStorageReport(type);
     if (reports == null ) {
       throw new IOException("Failed to get datanode storage report for " + type
@@ -880,6 +921,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // ClientProtocol
   public boolean setSafeMode(SafeModeAction action, boolean isChecked)
       throws IOException {
+    checkNNStartup();
     OperationCategory opCategory = OperationCategory.UNCHECKED;
     if (isChecked) {
       if (action == SafeModeAction.SAFEMODE_GET) {
@@ -894,27 +936,32 @@ class NameNodeRpcServer implements NamenodeProtocols {
 
   @Override // ClientProtocol
   public boolean restoreFailedStorage(String arg) throws IOException { 
+    checkNNStartup();
     return namesystem.restoreFailedStorage(arg);
   }
 
   @Override // ClientProtocol
   public void saveNamespace() throws IOException {
+    checkNNStartup();
     namesystem.saveNamespace();
   }
   
   @Override // ClientProtocol
   public long rollEdits() throws AccessControlException, IOException {
+    checkNNStartup();
     CheckpointSignature sig = namesystem.rollEditLog();
     return sig.getCurSegmentTxId();
   }
 
   @Override // ClientProtocol
   public void refreshNodes() throws IOException {
+    checkNNStartup();
     namesystem.refreshNodes();
   }
 
   @Override // NamenodeProtocol
   public long getTransactionID() throws IOException {
+    checkNNStartup();
     namesystem.checkOperation(OperationCategory.UNCHECKED);
     namesystem.checkSuperuserPrivilege();
     return namesystem.getFSImage().getLastAppliedOrWrittenTxId();
@@ -922,6 +969,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   
   @Override // NamenodeProtocol
   public long getMostRecentCheckpointTxId() throws IOException {
+    checkNNStartup();
     namesystem.checkOperation(OperationCategory.UNCHECKED);
     namesystem.checkSuperuserPrivilege();
     return namesystem.getFSImage().getMostRecentCheckpointTxId();
@@ -929,13 +977,15 @@ class NameNodeRpcServer implements NamenodeProtocols {
   
   @Override // NamenodeProtocol
   public CheckpointSignature rollEditLog() throws IOException {
+    checkNNStartup();
     namesystem.checkSuperuserPrivilege();
     return namesystem.rollEditLog();
   }
   
   @Override // NamenodeProtocol
   public RemoteEditLogManifest getEditLogManifest(long sinceTxId)
-  throws IOException {
+      throws IOException {
+    checkNNStartup();
     namesystem.checkOperation(OperationCategory.READ);
     namesystem.checkSuperuserPrivilege();
     return namesystem.getEditLog().getEditLogManifest(sinceTxId);
@@ -943,11 +993,13 @@ class NameNodeRpcServer implements NamenodeProtocols {
     
   @Override // ClientProtocol
   public void finalizeUpgrade() throws IOException {
+    checkNNStartup();
     namesystem.finalizeUpgrade();
   }
 
   @Override // ClientProtocol
   public RollingUpgradeInfo rollingUpgrade(RollingUpgradeAction action) throws IOException {
+    checkNNStartup();
     LOG.info("rollingUpgrade " + action);
     switch(action) {
     case QUERY:
@@ -964,12 +1016,14 @@ class NameNodeRpcServer implements NamenodeProtocols {
 
   @Override // ClientProtocol
   public void metaSave(String filename) throws IOException {
+    checkNNStartup();
     namesystem.metaSave(filename);
   }
 
   @Override // ClientProtocol
   public CorruptFileBlocks listCorruptFileBlocks(String path, String cookie)
       throws IOException {
+    checkNNStartup();
     String[] cookieTab = new String[] { cookie };
     Collection<FSNamesystem.CorruptFileBlockInfo> fbs =
       namesystem.listCorruptFileBlocks(path, cookieTab);
@@ -990,17 +1044,20 @@ class NameNodeRpcServer implements NamenodeProtocols {
    */
   @Override // ClientProtocol
   public void setBalancerBandwidth(long bandwidth) throws IOException {
+    checkNNStartup();
     namesystem.setBalancerBandwidth(bandwidth);
   }
   
   @Override // ClientProtocol
   public ContentSummary getContentSummary(String path) throws IOException {
+    checkNNStartup();
     return namesystem.getContentSummary(path);
   }
 
   @Override // ClientProtocol
   public void setQuota(String path, long namespaceQuota, long diskspaceQuota) 
       throws IOException {
+    checkNNStartup();
     namesystem.setQuota(path, namespaceQuota, diskspaceQuota);
   }
   
@@ -1008,18 +1065,21 @@ class NameNodeRpcServer implements NamenodeProtocols {
   public void fsync(String src, long fileId, String clientName,
                     long lastBlockLength)
       throws IOException {
+    checkNNStartup();
     namesystem.fsync(src, fileId, clientName, lastBlockLength);
   }
 
   @Override // ClientProtocol
   public void setTimes(String src, long mtime, long atime) 
       throws IOException {
+    checkNNStartup();
     namesystem.setTimes(src, mtime, atime);
   }
 
   @Override // ClientProtocol
   public void createSymlink(String target, String link, FsPermission dirPerms,
       boolean createParent) throws IOException {
+    checkNNStartup();
     metrics.incrCreateSymlinkOps();
     /* We enforce the MAX_PATH_LENGTH limit even though a symlink target 
      * URI may refer to a non-HDFS file system. 
@@ -1039,6 +1099,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
 
   @Override // ClientProtocol
   public String getLinkTarget(String path) throws IOException {
+    checkNNStartup();
     metrics.incrGetLinkTargetOps();
     HdfsFileStatus stat = null;
     try {
@@ -1061,6 +1122,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // DatanodeProtocol
   public DatanodeRegistration registerDatanode(DatanodeRegistration nodeReg)
       throws IOException {
+    checkNNStartup();
     verifySoftwareVersion(nodeReg);
     namesystem.registerDatanode(nodeReg);
     return nodeReg;
@@ -1071,6 +1133,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
       StorageReport[] report, long dnCacheCapacity, long dnCacheUsed,
       int xmitsInProgress, int xceiverCount,
       int failedVolumes) throws IOException {
+    checkNNStartup();
     verifyRequest(nodeReg);
     return namesystem.handleHeartbeat(nodeReg, report,
         dnCacheCapacity, dnCacheUsed, xceiverCount, xmitsInProgress,
@@ -1080,6 +1143,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // DatanodeProtocol
   public DatanodeCommand blockReport(DatanodeRegistration nodeReg,
       String poolId, StorageBlockReport[] reports) throws IOException {
+    checkNNStartup();
     verifyRequest(nodeReg);
     if(blockStateChangeLog.isDebugEnabled()) {
       blockStateChangeLog.debug("*BLOCK* NameNode.blockReport: "
@@ -1111,6 +1175,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override
   public DatanodeCommand cacheReport(DatanodeRegistration nodeReg,
       String poolId, List<Long> blockIds) throws IOException {
+    checkNNStartup();
     verifyRequest(nodeReg);
     if (blockStateChangeLog.isDebugEnabled()) {
       blockStateChangeLog.debug("*BLOCK* NameNode.cacheReport: "
@@ -1123,6 +1188,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // DatanodeProtocol
   public void blockReceivedAndDeleted(DatanodeRegistration nodeReg, String poolId,
       StorageReceivedDeletedBlocks[] receivedAndDeletedBlocks) throws IOException {
+    checkNNStartup();
     verifyRequest(nodeReg);
     metrics.incrBlockReceivedAndDeletedOps();
     if(blockStateChangeLog.isDebugEnabled()) {
@@ -1138,6 +1204,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // DatanodeProtocol
   public void errorReport(DatanodeRegistration nodeReg,
                           int errorCode, String msg) throws IOException { 
+    checkNNStartup();
     String dnName = 
        (nodeReg == null) ? "Unknown DataNode" : nodeReg.toString();
 
@@ -1159,6 +1226,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
     
   @Override // DatanodeProtocol, NamenodeProtocol
   public NamespaceInfo versionRequest() throws IOException {
+    checkNNStartup();
     namesystem.checkSuperuserPrivilege();
     return namesystem.getNamespaceInfo();
   }
@@ -1184,6 +1252,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
 
   @Override // RefreshAuthorizationPolicyProtocol
   public void refreshServiceAcl() throws IOException {
+    checkNNStartup();
     if (!serviceAuthEnabled) {
       throw new AuthorizationException("Service Level Authorization not enabled!");
     }
@@ -1234,28 +1303,32 @@ class NameNodeRpcServer implements NamenodeProtocols {
   }
 
   @Override // HAServiceProtocol
-  public synchronized void monitorHealth() 
-      throws HealthCheckFailedException, AccessControlException {
+  public synchronized void monitorHealth() throws HealthCheckFailedException,
+      AccessControlException, IOException {
+    checkNNStartup();
     nn.monitorHealth();
   }
   
   @Override // HAServiceProtocol
   public synchronized void transitionToActive(StateChangeRequestInfo req) 
-      throws ServiceFailedException, AccessControlException {
+      throws ServiceFailedException, AccessControlException, IOException {
+    checkNNStartup();
     nn.checkHaStateChange(req);
     nn.transitionToActive();
   }
   
   @Override // HAServiceProtocol
   public synchronized void transitionToStandby(StateChangeRequestInfo req) 
-      throws ServiceFailedException, AccessControlException {
+      throws ServiceFailedException, AccessControlException, IOException {
+    checkNNStartup();
     nn.checkHaStateChange(req);
     nn.transitionToStandby();
   }
 
   @Override // HAServiceProtocol
   public synchronized HAServiceStatus getServiceStatus() 
-      throws AccessControlException, ServiceFailedException {
+      throws AccessControlException, ServiceFailedException, IOException {
+    checkNNStartup();
     return nn.getServiceStatus();
   }
 
@@ -1312,12 +1385,14 @@ class NameNodeRpcServer implements NamenodeProtocols {
 
   @Override
   public DataEncryptionKey getDataEncryptionKey() throws IOException {
+    checkNNStartup();
     return namesystem.getBlockManager().generateDataEncryptionKey();
   }
 
   @Override
   public String createSnapshot(String snapshotRoot, String snapshotName)
       throws IOException {
+    checkNNStartup();
     if (!checkPathLength(snapshotRoot)) {
       throw new IOException("createSnapshot: Pathname too long.  Limit "
           + MAX_PATH_LENGTH + " characters, " + MAX_PATH_DEPTH + " levels.");
@@ -1329,6 +1404,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override
   public void deleteSnapshot(String snapshotRoot, String snapshotName)
       throws IOException {
+    checkNNStartup();
     metrics.incrDeleteSnapshotOps();
     namesystem.deleteSnapshot(snapshotRoot, snapshotName);
   }
@@ -1336,6 +1412,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override
   // Client Protocol
   public void allowSnapshot(String snapshotRoot) throws IOException {
+    checkNNStartup();
     metrics.incrAllowSnapshotOps();
     namesystem.allowSnapshot(snapshotRoot);
   }
@@ -1343,13 +1420,16 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override
   // Client Protocol
   public void disallowSnapshot(String snapshot) throws IOException {
+    checkNNStartup();
     metrics.incrDisAllowSnapshotOps();
     namesystem.disallowSnapshot(snapshot);
   }
 
   @Override
+  // ClientProtocol
   public void renameSnapshot(String snapshotRoot, String snapshotOldName,
       String snapshotNewName) throws IOException {
+    checkNNStartup();
     if (snapshotNewName == null || snapshotNewName.isEmpty()) {
       throw new IOException("The new snapshot name is null or empty.");
     }
@@ -1360,147 +1440,178 @@ class NameNodeRpcServer implements NamenodeProtocols {
   @Override // Client Protocol
   public SnapshottableDirectoryStatus[] getSnapshottableDirListing()
       throws IOException {
+    checkNNStartup();
     SnapshottableDirectoryStatus[] status = namesystem
         .getSnapshottableDirListing();
     metrics.incrListSnapshottableDirOps();
     return status;
   }
 
-  @Override
+  @Override // ClientProtocol
   public SnapshotDiffReport getSnapshotDiffReport(String snapshotRoot,
       String earlierSnapshotName, String laterSnapshotName) throws IOException {
+    checkNNStartup();
     SnapshotDiffReport report = namesystem.getSnapshotDiffReport(snapshotRoot,
         earlierSnapshotName, laterSnapshotName);
     metrics.incrSnapshotDiffReportOps();
     return report;
   }
 
-  @Override
+  @Override // ClientProtocol
   public long addCacheDirective(
       CacheDirectiveInfo path, EnumSet<CacheFlag> flags) throws IOException {
+    checkNNStartup();
     return namesystem.addCacheDirective(path, flags);
   }
 
-  @Override
+  @Override // ClientProtocol
   public void modifyCacheDirective(
       CacheDirectiveInfo directive, EnumSet<CacheFlag> flags) throws IOException {
+    checkNNStartup();
     namesystem.modifyCacheDirective(directive, flags);
   }
 
-  @Override
+  @Override // ClientProtocol
   public void removeCacheDirective(long id) throws IOException {
+    checkNNStartup();
     namesystem.removeCacheDirective(id);
   }
 
-  @Override
+  @Override // ClientProtocol
   public BatchedEntries<CacheDirectiveEntry> listCacheDirectives(long prevId,
       CacheDirectiveInfo filter) throws IOException {
+    checkNNStartup();
     if (filter == null) {
       filter = new CacheDirectiveInfo.Builder().build();
     }
     return namesystem.listCacheDirectives(prevId, filter);
   }
 
-  @Override
+  @Override //ClientProtocol
   public void addCachePool(CachePoolInfo info) throws IOException {
+    checkNNStartup();
     namesystem.addCachePool(info);
   }
 
-  @Override
+  @Override // ClientProtocol
   public void modifyCachePool(CachePoolInfo info) throws IOException {
+    checkNNStartup();
     namesystem.modifyCachePool(info);
   }
 
-  @Override
+  @Override // ClientProtocol
   public void removeCachePool(String cachePoolName) throws IOException {
+    checkNNStartup();
     namesystem.removeCachePool(cachePoolName);
   }
 
-  @Override
+  @Override // ClientProtocol
   public BatchedEntries<CachePoolEntry> listCachePools(String prevKey)
       throws IOException {
+    checkNNStartup();
     return namesystem.listCachePools(prevKey != null ? prevKey : "");
   }
 
-  @Override
+  @Override // ClientProtocol
   public void modifyAclEntries(String src, List<AclEntry> aclSpec)
       throws IOException {
+    checkNNStartup();
     namesystem.modifyAclEntries(src, aclSpec);
   }
 
-  @Override
+  @Override // ClienProtocol
   public void removeAclEntries(String src, List<AclEntry> aclSpec)
       throws IOException {
+    checkNNStartup();
     namesystem.removeAclEntries(src, aclSpec);
   }
 
-  @Override
+  @Override // ClientProtocol
   public void removeDefaultAcl(String src) throws IOException {
+    checkNNStartup();
     namesystem.removeDefaultAcl(src);
   }
 
-  @Override
+  @Override // ClientProtocol
   public void removeAcl(String src) throws IOException {
+    checkNNStartup();
     namesystem.removeAcl(src);
   }
 
-  @Override
+  @Override // ClientProtocol
   public void setAcl(String src, List<AclEntry> aclSpec) throws IOException {
+    checkNNStartup();
     namesystem.setAcl(src, aclSpec);
   }
 
-  @Override
+  @Override // ClientProtocol
   public AclStatus getAclStatus(String src) throws IOException {
+    checkNNStartup();
     return namesystem.getAclStatus(src);
   }
   
-  @Override
+  @Override // ClientProtocol
   public void createEncryptionZone(String src, String keyName)
     throws IOException {
+    checkNNStartup();
     namesystem.createEncryptionZone(src, keyName);
   }
 
-  @Override
+  @Override // ClientProtocol
   public EncryptionZone getEZForPath(String src)
     throws IOException {
+    checkNNStartup();
     return namesystem.getEZForPath(src);
   }
 
-  @Override
+  @Override // ClientProtocol
   public BatchedEntries<EncryptionZone> listEncryptionZones(
       long prevId) throws IOException {
+    checkNNStartup();
     return namesystem.listEncryptionZones(prevId);
   }
 
-  @Override
+  @Override // ClientProtocol
   public void setXAttr(String src, XAttr xAttr, EnumSet<XAttrSetFlag> flag)
       throws IOException {
+    checkNNStartup();
     namesystem.setXAttr(src, xAttr, flag);
   }
   
-  @Override
+  @Override // ClientProtocol
   public List<XAttr> getXAttrs(String src, List<XAttr> xAttrs) 
       throws IOException {
+    checkNNStartup();
     return namesystem.getXAttrs(src, xAttrs);
   }
 
-  @Override
+  @Override // ClientProtocol
   public List<XAttr> listXAttrs(String src) throws IOException {
+    checkNNStartup();
     return namesystem.listXAttrs(src);
   }
   
-  @Override
+  @Override // ClientProtocol
   public void removeXAttr(String src, XAttr xAttr) throws IOException {
+    checkNNStartup();
     namesystem.removeXAttr(src, xAttr);
   }
 
-  @Override
+  private void checkNNStartup() throws IOException {
+    if (!this.nn.isStarted()) {
+      throw new IOException(this.nn.getRole() + " still not started");
+    }
+  }
+
+  @Override // ClientProtocol
   public void checkAccess(String path, FsAction mode) throws IOException {
+    checkNNStartup();
     namesystem.checkAccess(path, mode);
   }
 
   @Override // ClientProtocol
   public long getCurrentEditLogTxid() throws IOException {
+    checkNNStartup();
     namesystem.checkOperation(OperationCategory.READ); // only active
     namesystem.checkSuperuserPrivilege();
     // if it's not yet open for write, we may be in the process of transitioning
@@ -1529,6 +1640,7 @@ class NameNodeRpcServer implements NamenodeProtocols {
 
   @Override // ClientProtocol
   public EventsList getEditsFromTxid(long txid) throws IOException {
+    checkNNStartup();
     namesystem.checkOperation(OperationCategory.READ); // only active
     namesystem.checkSuperuserPrivilege();
     int maxEventsPerRPC = nn.conf.getInt(
@@ -1610,20 +1722,23 @@ class NameNodeRpcServer implements NamenodeProtocols {
     return new EventsList(events, firstSeenTxid, maxSeenTxid, syncTxid);
   }
 
-  @Override
+  @Override // TraceAdminProtocol
   public SpanReceiverInfo[] listSpanReceivers() throws IOException {
+    checkNNStartup();
     namesystem.checkSuperuserPrivilege();
     return nn.spanReceiverHost.listSpanReceivers();
   }
 
-  @Override
+  @Override // TraceAdminProtocol
   public long addSpanReceiver(SpanReceiverInfo info) throws IOException {
+    checkNNStartup();
     namesystem.checkSuperuserPrivilege();
     return nn.spanReceiverHost.addSpanReceiver(info);
   }
 
-  @Override
+  @Override // TraceAdminProtocol
   public void removeSpanReceiver(long id) throws IOException {
+    checkNNStartup();
     namesystem.checkSuperuserPrivilege();
     nn.spanReceiverHost.removeSpanReceiver(id);
   }