Merge HDFS-4482. ReplicationMonitor thread can exit with NPE due to the race between delete and replication of same file. Contributed by Uma Maheswara Rao G.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1448716 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -22,6 +22,9 @@ Release 2.0.4-beta - UNRELEASED
     but not in dfs.namenode.edits.dir are silently ignored.  (Arpit Agarwal
     via szetszwo)
 
+    HDFS-4482. ReplicationMonitor thread can exit with NPE due to the race 
+    between delete and replication of same file. (umamahesh)
+
 Release 2.0.3-alpha - 2013-02-06
 
   INCOMPATIBLE CHANGES

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

@@ -1421,6 +1421,11 @@ public class FSDirectory implements Closeable {
 
     // fill up the inodes in the path from this inode to root
     for (int i = 0; i < depth; i++) {
+      if (inode == null) {
+        NameNode.stateChangeLog.warn("Could not get full path."
+            + " Corresponding file might have deleted already.");
+        return null;
+      }
       inodes[depth-i-1] = inode;
       inode = inode.parent;
     }

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

@@ -237,7 +237,11 @@ abstract class INode implements Comparable<byte[]> {
 
   String getLocalParentDir() {
     INode inode = isRoot() ? this : getParent();
-    return (inode != null) ? inode.getFullPathName() : "";
+    String parentDir = "";
+    if (inode != null) {
+      parentDir = inode.getFullPathName();
+    }
+    return (parentDir != null) ? parentDir : "";
   }
 
   /**