HDFS-7340. Make rollingUpgrade start/finalize idempotent. Contributed by Jing Zhao.

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

@@ -714,6 +714,8 @@ Release 2.6.0 - UNRELEASED
     HDFS-7147. Update archival storage user documentation.
     (Tsz Wo Nicholas Sze via wheat9)
 
+    HDFS-7340. Make rollingUpgrade start/finalize idempotent. (jing9)
+
     BREAKDOWN OF HDFS-6134 AND HADOOP-10150 SUBTASKS AND RELATED JIRAS
   
       HDFS-6387. HDFS CLI admin tool for creating & deleting an

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

@@ -8282,6 +8282,9 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     writeLock();
     try {
       checkOperation(OperationCategory.WRITE);
+      if (isRollingUpgrade()) {
+        return rollingUpgradeInfo;
+      }
       long startTime = now();
       if (!haEnabled) { // for non-HA, we require NN to be in safemode
         startRollingUpgradeInternalForNonHA(startTime);
@@ -8390,13 +8393,16 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     }
   }
 
-  RollingUpgradeInfo finalizeRollingUpgrade() throws IOException {
+  void finalizeRollingUpgrade() throws IOException {
     checkSuperuserPrivilege();
     checkOperation(OperationCategory.WRITE);
     writeLock();
     final RollingUpgradeInfo returnInfo;
     try {
       checkOperation(OperationCategory.WRITE);
+      if (!isRollingUpgrade()) {
+        return;
+      }
       checkNameNodeSafeMode("Failed to finalize rolling upgrade");
 
       returnInfo = finalizeRollingUpgradeInternal(now());
@@ -8420,16 +8426,11 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     if (auditLog.isInfoEnabled() && isExternalInvocation()) {
       logAuditEvent(true, "finalizeRollingUpgrade", null, null, null);
     }
-    return returnInfo;
+    return;
   }
 
   RollingUpgradeInfo finalizeRollingUpgradeInternal(long finalizeTime)
       throws RollingUpgradeException {
-    if (!isRollingUpgrade()) {
-      throw new RollingUpgradeException(
-          "Failed to finalize rolling upgrade since there is no rolling upgrade in progress.");
-    }
-
     final long startTime = rollingUpgradeInfo.getStartTime();
     rollingUpgradeInfo = null;
     return new RollingUpgradeInfo(blockPoolId, false, startTime, finalizeTime);

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

@@ -954,7 +954,8 @@ class NameNodeRpcServer implements NamenodeProtocols {
     case PREPARE:
       return namesystem.startRollingUpgrade();
     case FINALIZE:
-      return namesystem.finalizeRollingUpgrade();
+      namesystem.finalizeRollingUpgrade();
+      return null;
     default:
       throw new UnsupportedActionException(action + " is not yet supported.");
     }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/DFSAdmin.java

@@ -331,7 +331,8 @@ public class DFSAdmin extends FsShell {
           out.println(info);
         }
       } else {
-        out.println("There is no rolling upgrade in progress.");
+        out.println("There is no rolling upgrade in progress or rolling " +
+            "upgrade has already been finalized.");
       }
     }
 
@@ -353,7 +354,7 @@ public class DFSAdmin extends FsShell {
         Preconditions.checkState(info.isStarted());
         break;
       case FINALIZE:
-        Preconditions.checkState(info.isFinalized());
+        Preconditions.checkState(info == null || info.isFinalized());
         break;
       }
       printMessage(info, System.out);

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestRollingUpgrade.java

@@ -239,9 +239,9 @@ public class TestRollingUpgrade {
       Assert.assertTrue(dfs2.exists(baz));
 
       //finalize rolling upgrade
-      final RollingUpgradeInfo finalize = dfs2.rollingUpgrade(RollingUpgradeAction.FINALIZE);
+      final RollingUpgradeInfo finalize = dfs2.rollingUpgrade(
-      LOG.info("FINALIZE: " + finalize);
+          RollingUpgradeAction.FINALIZE);
-      Assert.assertEquals(info1.getStartTime(), finalize.getStartTime());
+      Assert.assertNull(finalize);
 
       LOG.info("RESTART cluster 2 with regular startup option");
       cluster2.getNameNodeInfos()[0].setStartOpt(StartupOption.REGULAR);
@@ -385,7 +385,7 @@ public class TestRollingUpgrade {
       Assert.assertTrue(fsimage.hasRollbackFSImage());
 
       info = dfs.rollingUpgrade(RollingUpgradeAction.FINALIZE);
-      Assert.assertTrue(info.isFinalized());
+      Assert.assertNull(info);
       Assert.assertTrue(dfs.exists(foo));
 
       // Once finalized, there should be no more fsimage for rollbacks.