HDFS-5723. Append failed FINALIZED replica should not be accepted as valid when that block is underconstruction. Contributed by Vinayakumar B.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1615491 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5185. DN fails to startup if one of the data dir is full. Contributed by Vinayakumar B.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1615504 13f79535-47bb-0310-9956-ffa450edef68