From 6f622672b62aa8d719060063ef0e47480cdc8655 Mon Sep 17 00:00:00 2001
From: Kihwal Lee <kihwal@apache.org>
Date: Fri, 8 May 2015 09:30:38 -0500
Subject: [PATCH] HDFS-7894. Rolling upgrade readiness is not updated in jmx
 until query command is issued. Contributed by Brahma Reddy Battula.

---
 hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt   |  3 +++
 .../hdfs/server/namenode/FSNamesystem.java    | 23 +++++++++++++++++--
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 60825a2be8..a83b8a79e9 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -765,6 +765,9 @@ Release 2.7.1 - UNRELEASED
 
     HDFS-8226. Non-HA rollback compatibility broken (J.Andreina via vinayakumarb)
 
+    HDFS-7894. Rolling upgrade readiness is not updated in jmx until query
+    command is issued. (Brahma Reddy Battula  via kihwal)
+
 Release 2.7.0 - 2015-04-20
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
index 120812bc96..60495af9da 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
@@ -7608,11 +7608,30 @@ public void setNeedRollbackFsImage(boolean needRollbackFsImage) {
 
   @Override  // NameNodeMXBean
   public RollingUpgradeInfo.Bean getRollingUpgradeStatus() {
+    if (!isRollingUpgrade()) {
+      return null;
+    }
     RollingUpgradeInfo upgradeInfo = getRollingUpgradeInfo();
-    if (upgradeInfo != null) {
+    if (upgradeInfo.createdRollbackImages()) {
       return new RollingUpgradeInfo.Bean(upgradeInfo);
     }
-    return null;
+    readLock();
+    try {
+      // check again after acquiring the read lock.
+      upgradeInfo = getRollingUpgradeInfo();
+      if (upgradeInfo == null) {
+        return null;
+      }
+      if (!upgradeInfo.createdRollbackImages()) {
+        boolean hasRollbackImage = this.getFSImage().hasRollbackFSImage();
+        upgradeInfo.setCreatedRollbackImages(hasRollbackImage);
+      }
+    } catch (IOException ioe) {
+      LOG.warn("Encountered exception setting Rollback Image", ioe);
+    } finally {
+      readUnlock();
+    }
+    return new RollingUpgradeInfo.Bean(upgradeInfo);
   }
 
   /** Is rolling upgrade in progress? */