HDFS-6304. Consolidate the logic of path resolution in FSDirectory. Contributed by Haohui Mai.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1591411 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6289. HA failover can fail if there are pending DN messages for DNs which no longer exist. Contributed by Aaron T. Myers.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1591413 13f79535-47bb-0310-9956-ffa450edef68