HDFS-5710. Merge change r1557803 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1557805 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -262,6 +262,9 @@ Release 2.4.0 - UNRELEASED
 
     HDFS-5747. Fix NPEs in BlockManager. (Arpit Agarwal)
 
+    HDFS-5710. FSDirectory#getFullPathName should check inodes against null.
+    (Uma Maheswara Rao G via jing9)
+
   BREAKDOWN OF HDFS-2832 SUBTASKS AND RELATED JIRAS
 
     HDFS-4985. Add storage type to the protocol and expose it in block report

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

@@ -1884,7 +1884,8 @@ public class FSDirectory implements Closeable {
   /** Return the full path name of the specified inode */
   static String getFullPathName(INode inode) {
     INode[] inodes = getFullPathINodes(inode);
-    return getFullPathName(inodes, inodes.length - 1);
+    // inodes can be null only when its called without holding lock
+    return inodes == null ? "" : getFullPathName(inodes, inodes.length - 1);
   }
   
   /**