HDFS-10763. Open files can leak permanently due to inconsistent lease update. Contributed by Kihwal Lee.

(cherry picked from commit 61e1348fe479872b0eb1b53c50b248b33b37d77b)

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

@@ -47,6 +47,9 @@ Release 2.6.5 - UNRELEASED
 
     HDFS-9696. Garbage snapshot records linger forever. (kihwal)
 
+    HDFS-10763. Open files can leak permanently due to inconsistent
+    lease update (kihwal)
+
 Release 2.6.4 - 2016-02-11
 
   INCOMPATIBLE CHANGES

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

@@ -179,11 +179,13 @@ public final class FSImageFormatPBINode {
     private final FSDirectory dir;
     private final FSNamesystem fsn;
     private final FSImageFormatProtobuf.Loader parent;
+    private final List<INodeFile> ucFiles;
 
     Loader(FSNamesystem fsn, final FSImageFormatProtobuf.Loader parent) {
       this.fsn = fsn;
       this.dir = fsn.dir;
       this.parent = parent;
+      this.ucFiles = new ArrayList<INodeFile>();
     }
 
     void loadINodeDirectorySection(InputStream in) throws IOException {
@@ -227,17 +229,25 @@ public final class FSImageFormatPBINode {
      * Load the under-construction files section, and update the lease map
      */
     void loadFilesUnderConstructionSection(InputStream in) throws IOException {
+     // This section is consumed, but not actually used for restoring leases.
       while (true) {
         FileUnderConstructionEntry entry = FileUnderConstructionEntry
             .parseDelimitedFrom(in);
         if (entry == null) {
           break;
         }
-        // update the lease manager
-        INodeFile file = dir.getInode(entry.getInodeId()).asFile();
+      }
+
+      // Add a lease for each and every file under construction.
+      for (INodeFile file : ucFiles) {
         FileUnderConstructionFeature uc = file.getFileUnderConstructionFeature();
         Preconditions.checkState(uc != null); // file must be under-construction
-        fsn.leaseManager.addLease(uc.getClientName(), entry.getFullPath());
+        String path = file.getFullPathName();
+        // Skip the deleted files in snapshot. This leaks UC inodes that are
+        // deleted from the current view.
+        if (path.startsWith("/")) {
+          fsn.leaseManager.addLease(uc.getClientName(), path);
+        }
       }
     }
 
@@ -304,6 +314,7 @@ public final class FSImageFormatPBINode {
 
       // under-construction information
       if (f.hasFileUC()) {
+        ucFiles.add(file);
         INodeSection.FileUnderConstructionFeature uc = f.getFileUC();
         file.toUnderConstruction(uc.getClientName(), uc.getClientMachine());
         if (blocks.length > 0) {

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

@@ -4699,7 +4699,6 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
       throw new IOException("Cannot finalize file " + src
           + " because it is not under construction");
     }
-    leaseManager.removeLease(uc.getClientName(), src);
     
     pendingFile.recordModification(latestSnapshot);
 
@@ -4708,6 +4707,8 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     // since we just remove the uc feature from pendingFile
     final INodeFile newFile = pendingFile.toCompleteFile(now());
 
+    leaseManager.removeLease(uc.getClientName(), src);
+
     waitForLoadingFSImage();
     // close file and persist block allocations for this file
     closeFile(src, newFile);

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestLeaseManager.java

@@ -21,9 +21,13 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 
+import org.apache.hadoop.fs.FSDataOutputStream;
+import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hdfs.DistributedFileSystem;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
 import org.junit.Test;
 import org.mockito.Mockito;
 
@@ -79,4 +83,43 @@ public class TestLeaseManager {
     //Initiate a call to checkLease. This should exit within the test timeout
     lm.checkLeases();
   }
+
+  /**
+   * Make sure the lease is restored even if only the inode has the record.
+   */
+  @Test
+  public void testLeaseRestorationOnRestart() throws Exception {
+    MiniDFSCluster cluster = null;
+    try {
+      cluster = new MiniDFSCluster.Builder(new HdfsConfiguration())
+          .numDataNodes(1).build();
+      DistributedFileSystem dfs = cluster.getFileSystem();
+
+      // Create an empty file
+      String path = "/testLeaseRestorationOnRestart";
+      FSDataOutputStream out = dfs.create(new Path(path));
+
+      // Remove the lease from the lease manager, but leave it in the inode.
+      FSDirectory dir = cluster.getNamesystem().getFSDirectory();
+      INodeFile file = dir.getINode(path).asFile();
+      cluster.getNamesystem().leaseManager.removeLease(
+          file.getFileUnderConstructionFeature().getClientName(), path);
+
+      // Save a fsimage.
+      dfs.setSafeMode(SafeModeAction.SAFEMODE_ENTER);
+      cluster.getNameNodeRpc().saveNamespace();
+      dfs.setSafeMode(SafeModeAction.SAFEMODE_LEAVE);
+
+      // Restart the namenode.
+      cluster.restartNameNode(true);
+
+      // Check whether the lease manager has the lease
+      assertNotNull("Lease should exist",
+          cluster.getNamesystem().leaseManager.getLeaseByPath(path));
+    } finally {
+      if (cluster != null) {
+        cluster.shutdown();
+      }
+    }
+  }
 }