HDFS-16697.Randomly setting “dfs.namenode.resource.checked.volumes.minimum” will always prevent safe mode from being turned off

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

@@ -174,6 +174,19 @@ private void addDirToCheck(URI directoryToCheck, boolean required)
    *         otherwise.
    */
   public boolean hasAvailableDiskSpace() {
+    try {
+      if (minimumRedundantVolumes > volumes.size()){
+        throw new IllegalArgumentException("The value of "
+        + DFSConfigKeys.DFS_NAMENODE_CHECKED_VOLUMES_MINIMUM_KEY
+        + " is " + minimumRedundantVolumes
+        + " which is greater than the total number of existing storage volumes "
+        + volumes.size() + " .");
+      }
+    } catch (IllegalArgumentException e){
+      LOG.warn("The value of " + DFSConfigKeys.DFS_NAMENODE_CHECKED_VOLUMES_MINIMUM_KEY
+      + " is greater than the total number of existing storage volumes"
+      + " and will result in adding resources and still not being able to turn off safe mode.", e);
+    }
     return NameNodeResourcePolicy.areResourcesAvailable(volumes.values(),
         minimumRedundantVolumes);
   }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNameNodeResourceChecker.java

@@ -7,8 +7,10 @@
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
+ *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.