HDFS-6576. Datanode log is generating at root directory in security mode (Contributed by surendra singh lilhore) Just merging CHANGES.txt changes from branch-2 to keep in sync.
HDFS-6576. Datanode log is generating at root directory in security mode (Contributed by surendra singh lilhore)
Just merging CHANGES.txt changes from branch-2 to keep in sync.

(cherry picked from commit a87ab77fec375c02ba507bd7c7ca1e0082f623c2)

Conflicts:
	hadoop-common-project/hadoop-common/src/main/conf/hadoop-env.sh

zjshen/hadoop-YARN-2928-POC,zjshen/hadoop-YARN-2928-POC,zjshen/hadoop-YARN-2928-POC,zjshen/hadoop-YARN-2928-POC,zjshen/hadoop-YARN-2928-POC,zjshen/hadoop-YARN-2928-POC,zjshen/hadoop-YARN-2928-POC