HDFS-3332. NullPointerException in DN when directoryscanner is trying to report bad blocks. Contributed by Amith D K.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1333587 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPServiceActor.java

@@ -235,6 +235,9 @@ class BPServiceActor implements Runnable {
   }
 
   void reportBadBlocks(ExtendedBlock block) {
+    if (bpRegistration == null) {
+      return;
+    }
     DatanodeInfo[] dnArr = { new DatanodeInfo(bpRegistration) };
     LocatedBlock[] blocks = { new LocatedBlock(block, dnArr) };