HDFS-6617. Merging change r1608522 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1608523 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10782. Merge r1608539 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1608541 13f79535-47bb-0310-9956-ffa450edef68