HDFS-6227. Merge r1597829 from trunk.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1597830 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6416. Merging change r1597868 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1597870 13f79535-47bb-0310-9956-ffa450edef68