HDFS-5164. DeleteSnapshot should check if OperationCategory.WRITE is possible before taking write lock (contributed by Colin Patrick McCabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1520494 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -45,6 +45,9 @@ Release 2.3.0 - UNRELEASED
     HDFS-4816. transitionToActive blocks if the SBN is doing checkpoint image
     transfer. (Andrew Wang)
 
+    HDFS-5164.  deleteSnapshot should check if OperationCategory.WRITE is
+    possible before taking write lock.  (Colin Patrick McCabe)
+
 Release 2.1.1-beta - UNRELEASED
 
   INCOMPATIBLE CHANGES

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

@@ -6750,6 +6750,7 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
       return; // Return previous response
     }
     boolean success = false;
+    checkOperation(OperationCategory.WRITE);
     writeLock();
     try {
       checkOperation(OperationCategory.WRITE);