HDFS-2933. Merging changes r1515890 and r1515892 from trunk to branch-2.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1515894 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5111. Merge change r1515895 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1515896 13f79535-47bb-0310-9956-ffa450edef68