HDFS-5329. Merging change 1531617 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1531618 13f79535-47bb-0310-9956-ffa450edef68

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
HDFS-5330. Merging change r1532539 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1532543 13f79535-47bb-0310-9956-ffa450edef68

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs-nfs/src/main/java/org/apache/hadoop/hdfs/nfs/nfs3/WriteManager.java
	hadoop-hdfs-project/hadoop-hdfs-nfs/src/test/java/org/apache/hadoop/hdfs/nfs/nfs3/TestWrites.java
	hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
Merge pull request #52 from VertiPub/zx-HD-226

HD-226 fix readdir and readdirplus for large directories