HDFS-16785. Avoid to hold write lock to improve performance when add volume. (#4945). Contributed by ZanderXu.

Signed-off-by: Tao Li <tomscut@apache.org>
Signed-off-by: He Xiaoqiao <hexiaoqiao@apache.org>

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java

@@ -520,7 +520,7 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
 
     for (final NamespaceInfo nsInfo : nsInfos) {
       String bpid = nsInfo.getBlockPoolID();
-      try (AutoCloseDataSetLock l = lockManager.writeLock(LockLevel.BLOCK_POOl, bpid)) {
+      try {
         fsVolume.addBlockPool(bpid, this.conf, this.timer);
         fsVolume.getVolumeMap(bpid, tempVolumeMap, ramDiskReplicaTracker);
       } catch (IOException e) {