Flaky test TestFsDatasetImpl#testDnRestartWithHardLink

[ERROR] testDnRestartWithHardLink(org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.TestFsDatasetImpl)  Time elapsed: 7.768 s  <<< FAILURE![ERROR] testDnRestartWithHardLink(org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.TestFsDatasetImpl)  Time elapsed: 7.768 s  <<< FAILURE!java.lang.AssertionError at org.junit.Assert.fail(Assert.java:87) at org.junit.Assert.assertTrue(Assert.java:42) at org.junit.Assert.assertTrue(Assert.java:53) at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.TestFsDatasetImpl.testDnRestartWithHardLink(TestFsDatasetImpl.java:1344) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:299) at org.junit.internal.runners.statements.FailOnTimeout$CallableStatement.call(FailOnTimeout.java:293) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.lang.Thread.run(Thread.java:748)