fix failed UT.

Author: hfutatzhanghb

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/ModDataSetSubLockStrategy.java

@@ -39,7 +39,7 @@ public ModDataSetSubLockStrategy(long mod) {
 
   @Override
   public String blockIdToSubLock(long blockid) {
-    return LOCK_NAME_PERFIX + String.valueOf(blockid % modFactor);
+    return LOCK_NAME_PERFIX + (blockid % modFactor);
   }
 
   @Override

hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml

@@ -6568,6 +6568,15 @@
       problem. In produce default set false, because it's have little performance loss.
     </description>
   </property>
+
+  <property>
+    <name>dfs.datanode.dataset.sublock.count</name>
+    <value>1000</value>
+    <description>
+      The dataset readwrite lock counts for a volume.
+    </description>
+  </property>
+
   <property>
     <name>dfs.client.fsck.connect.timeout</name>
     <value>60000ms</value>