From bf44d16ef467405a13fa95a6805a4a3ca1e2d898 Mon Sep 17 00:00:00 2001
From: Uma Maheswara Rao G <umamahesh@apache.org>
Date: Thu, 21 Feb 2013 16:25:12 +0000
Subject: [PATCH] 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/trunk@1448708 13f79535-47bb-0310-9956-ffa450edef68
---
 hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt                 | 3 +++
 .../org/apache/hadoop/hdfs/server/namenode/FSDirectory.java | 5 +++++
 .../java/org/apache/hadoop/hdfs/server/namenode/INode.java  | 6 +++++-
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index cffbed41fe7..3b1a1e36bce 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -324,6 +324,9 @@ 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
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java
index 9becf41174d..b11059a4bb4 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java
@@ -1343,6 +1343,11 @@ 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;
     }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INode.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INode.java
index 91ff0891c96..b407a62da97 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INode.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INode.java
@@ -282,7 +282,11 @@ 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 : "";
   }
 
   /**