HDFS-642. Support pipeline close and close error recovery. Contributed by Hairong Kuang.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/hdfs/branches/HDFS-265@820055 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -50,6 +50,8 @@ Append branch (unreleased changes)
    HDFS-627. Support replica update in data-node.
    (Tsz Wo (Nicholas), SZE and Hairong Kuang via shv)
 
+   HDFS-642. Support pipeline close and close error recovery. (hairong)
+
   IMPROVEMENTS
 
     HDFS-509. Redesign DataNode volumeMap to include all types of Replicas.