HDFS-4395. In INodeDirectorySnapshottable's constructor, the passed-in dir could be an INodeDirectoryWithSnapshot. Contributed by Jing Zhao

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-2802@1432838 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.HDFS-2802.txt

@@ -104,3 +104,6 @@ Branch-2802 Snapshot (Unreleased)
   HDFS-4098. Add FileWithLink, INodeFileUnderConstructionWithLink and
   INodeFileUnderConstructionSnapshot in order to support append to snapshotted
   files.  (szetszwo)
+
+  HDFS-4395. In INodeDirectorySnapshottable's constructor, the passed-in dir
+  could be an INodeDirectoryWithSnapshot.  (Jing Zhao via szetszwo)

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

@@ -76,7 +76,8 @@ public class INodeDirectorySnapshottable extends INodeDirectoryWithSnapshot {
   private int snapshotQuota = SNAPSHOT_LIMIT;
 
   public INodeDirectorySnapshottable(INodeDirectory dir) {
-    super(dir, true, null);
+    super(dir, true, dir instanceof INodeDirectoryWithSnapshot ? 
+        ((INodeDirectoryWithSnapshot) dir).getSnapshotDiffs() : null);
   }
   
   /** @return the number of existing snapshots. */