svn merge -c 1576149 from branch-2 for HDFS-6060. NameNode should not check DataNode layout version

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.4@1576150 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -627,6 +627,8 @@ HDFS-5535 subtasks:
     HDFS-6041. Downgrade/Finalize should rename the rollback image instead of
     purging it. (jing9)
 
+    HDFS-6060. NameNode should not check DataNode layout version (brandonli)
+
 Release 2.3.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java

@@ -105,7 +105,6 @@ import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifie
 import org.apache.hadoop.hdfs.server.blockmanagement.BlockManager;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NamenodeRole;
 import org.apache.hadoop.hdfs.server.common.IncorrectVersionException;
-import org.apache.hadoop.hdfs.server.datanode.DataNodeLayoutVersion;
 import org.apache.hadoop.hdfs.server.namenode.NameNode.OperationCategory;
 import org.apache.hadoop.hdfs.server.namenode.metrics.NameNodeMetrics;
 import org.apache.hadoop.hdfs.server.namenode.web.resources.NamenodeWebHdfsMethods;
@@ -1097,20 +1096,6 @@ class NameNodeRpcServer implements NamenodeProtocols {
           + " but the expected ID is " + expectedID);
        throw new UnregisteredNodeException(nodeReg);
     }
-
-    // verify layout version if there is no rolling upgrade.
-    if (!namesystem.isRollingUpgrade()) {
-      final int lv = nodeReg.getVersion();
-      final int expectedLV = nodeReg instanceof NamenodeRegistration?
-          NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION
-          : DataNodeLayoutVersion.CURRENT_LAYOUT_VERSION;
-      if (expectedLV != nodeReg.getVersion()) {
-        LOG.warn("Layout versions mismatched: the "
-            + nodeReg.getClass().getSimpleName() + " LV is " + lv
-            + " but the expected LV is " + expectedLV);
-         throw new UnregisteredNodeException(nodeReg);
-      }
-    }
   }