HDFS-12040. TestFsDatasetImpl.testCleanShutdownOfVolume fails. Contributed by hu xiaodong.

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/TestFsDatasetImpl.java

@@ -687,7 +687,7 @@ public class TestFsDatasetImpl {
           @Override public Boolean get() {
               return volume.getReferenceCount() == 0;
             }
-          }, 100, 10);
+          }, 100, 1000);
       assertThat(dataNode.getFSDataset().getNumFailedVolumes(), is(1));
 
       try {