HDFS-4972. Permission check and operation are done in a separate lock for getBlockLocations(). Contributed by Kihwal Lee.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1503461 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5317. Stale files left behind for failed jobs. Contributed by Ravi Prakash


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Merge remote branch 'origin/branch-0.23' into branch-0.23-gd
Merge remote branch 'origin/branch-0.23-gd' into fb-YAHOO-270-branch-0.23-gd