HDFS-6838. Code cleanup for unnecessary INode replacement. Contributed by Jing Zhao.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1617361 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6582. Missing null check in RpcProgramNfs3#read(XDR, SecurityHandler). Contributed by Abhiraj Butala

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1617366 13f79535-47bb-0310-9956-ffa450edef68