HDFS-8626. Add test case for branch-2.7

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

@@ -27,10 +27,13 @@ import org.apache.hadoop.conf.Configuration;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.*;
 import static org.hamcrest.core.Is.is;
 import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.*;
+import org.apache.hadoop.hdfs.protocol.Block;
 import org.apache.hadoop.hdfs.server.datanode.DataNode;
 import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsVolumeSpi;
 import org.apache.hadoop.ipc.RemoteException;
@@ -41,10 +44,13 @@ import org.junit.After;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
+import org.mockito.Mockito;
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.lang.reflect.Field;
 import java.util.List;
+import java.util.Map;
 import java.util.Random;
 import java.util.concurrent.TimeoutException;
 
@@ -276,6 +282,45 @@ public class TestRbwSpaceReservation {
     }
   }
 
+  @SuppressWarnings("unchecked")
+  @Test(timeout = 30000)
+  public void testRBWFileCreationError() throws Exception {
+
+    final short replication = 1;
+    startCluster(BLOCK_SIZE, replication, -1);
+
+    final FsVolumeImpl fsVolumeImpl = (FsVolumeImpl) cluster.getDataNodes()
+        .get(0).getFSDataset().getVolumes().get(0);
+    final String methodName = GenericTestUtils.getMethodName();
+    final Path file = new Path("/" + methodName + ".01.dat");
+
+    // Mock BlockPoolSlice so that RBW file creation gives IOExcception
+    BlockPoolSlice blockPoolSlice = Mockito.mock(BlockPoolSlice.class);
+    Mockito.when(blockPoolSlice.createRbwFile((Block) Mockito.any()))
+        .thenThrow(new IOException("Synthetic IO Exception Throgh MOCK"));
+
+    Field field = FsVolumeImpl.class.getDeclaredField("bpSlices");
+    field.setAccessible(true);
+    Map<String, BlockPoolSlice> bpSlices = (Map<String, BlockPoolSlice>) field
+        .get(fsVolumeImpl);
+    bpSlices.put(fsVolumeImpl.getBlockPoolList()[0], blockPoolSlice);
+
+    try {
+      // Write 1 byte to the file
+      FSDataOutputStream os = fs.create(file, replication);
+      os.write(new byte[1]);
+      os.hsync();
+      os.close();
+      fail("Expecting IOException file creation failure");
+    } catch (IOException e) {
+      // Exception can be ignored (expected)
+    }
+
+    // Ensure RBW space reserved is released
+    assertTrue("Expected ZERO but got " + fsVolumeImpl.getReservedForRbw(),
+        fsVolumeImpl.getReservedForRbw() == 0);
+  }
+
   /**
    * Stress test to ensure we are not leaking reserved space.
    * @throws IOException