HDFS-13359. DataXceiver hung due to the lock in FsDatasetImpl#getBlockInputStream. Contributed by Yiqun Lin.

Signed-off-by: Wei-Chiu Chuang <weichiu@apache.org>
(cherry picked from commit 8a77a224c734bea0eb490f30c908748458c190c3)

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

@@ -778,7 +778,7 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
       long seekOffset) throws IOException {
 
     ReplicaInfo info;
-    synchronized(this) {
+    try (AutoCloseableLock lock = datasetLock.acquire()) {
       info = volumeMap.get(b.getBlockPoolId(), b.getLocalBlock());
     }