YARN-90. NodeManager should identify failed disks becoming good again. Contributed by Varun Vasudev
(cherry picked from commit 6f2028bd1514d90b831f889fd0ee7f2ba5c15000)

Conflicts:

	hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/test/java/org/apache/hadoop/yarn/server/nodemanager/TestDirectoryCollection.java
HDFS-7259. Unresponseive NFS mount point due to deferred COMMIT response. Contributed by Brandon Li

(cherry picked from commit 33e020cb191dc7264b7f683cff7d20980b6919c8)