Create a branch for HDFS-5535 Rolling upgrade improvement.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1550130 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5496. Make replication queue initialization asynchronous. Contributed by Vinay.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1552109 13f79535-47bb-0310-9956-ffa450edef68
Merge r1550130 through r1555020 from trunk.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1555021 13f79535-47bb-0310-9956-ffa450edef68
add CHANGES_HDFS-5535.txt.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1555023 13f79535-47bb-0310-9956-ffa450edef68
Merge r1555021 through r1556550 from trunk.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1556552 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5645. Support upgrade marker in editlog streams.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1557038 13f79535-47bb-0310-9956-ffa450edef68
Merge r1555021 through r1557038 from trunk.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1557039 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5752. Add a new DFSAdmin command to query, start and finalize rolling upgrade.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1558299 13f79535-47bb-0310-9956-ffa450edef68
Merge r1555021 through r1558254 from trunk.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1558303 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5786. Support QUERY and FINALIZE actions of rolling upgrade.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1559304 13f79535-47bb-0310-9956-ffa450edef68
Merge r1555021 through r1559304 from trunk.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1559305 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5753. Add new NN startup options for downgrade and rollback using upgrade marker.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1559907 13f79535-47bb-0310-9956-ffa450edef68
Merge r1555021 through r1561510 from trunk.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1561516 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5835. Add a new option for starting Namenode when rolling upgrade is in progress.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1561943 13f79535-47bb-0310-9956-ffa450edef68
Merge r1555021 through r1561943 from trunk.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1561944 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5754. Split LayoutVerion into NameNodeLayoutVersion and DataNodeLayoutVersion. Contributed by Brandon Li


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1563041 13f79535-47bb-0310-9956-ffa450edef68
Merge r1555021 through r1563041 from trunk.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1563042 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5848. Add rolling upgrade status to heartbeat response.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1563384 13f79535-47bb-0310-9956-ffa450edef68
Merge r1555021 through r1563384 from trunk.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1563385 13f79535-47bb-0310-9956-ffa450edef68
HDFS-5890. Avoid NPE in Datanode heartbeat. Contributed by Vinay

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-5535@1565023 13f79535-47bb-0310-9956-ffa450edef68