HDFS-6570. Merging change r1614723 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1614726 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6768: Merging r1614732 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1614733 13f79535-47bb-0310-9956-ffa450edef68