HADOOP-8562. Merge r1459586 for HDFS-4615, r1459592 for HDFS-4584, r1459643, r1459642 for HADOOP-9387, r1460086 for HADOOP-9353

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1485932 13f79535-47bb-0310-9956-ffa450edef68