nfsv4.1: resulting notification bitmap should match requests length

Motivation:
Though bitmap can have an arbitrary length, the linux 5.10 client expects
device notification bitmap to be size of one (1).

Modification:
Update OperationGETDEVICEINFO to initialize resulting notification bitmap
with the length that matches requested notification bitmap.

Result:
Linux 5.10 client processes the result of getdeviceinfo operation as expected.

Target: 0.22, master
Acked-by: Paul Millar
Acked-by: Albert Rossi
(cherry picked from commit 8ede287)
Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>

core/src/main/java/org/dcache/nfs/v4/OperationGETDEVICEINFO.java

@@ -72,7 +72,8 @@ public void process(CompoundContext context, nfs_resop4 result) throws IOExcepti
         }
 
         res.gdir_resok4.gdir_device_addr = deviceInfo;
-        res.gdir_resok4.gdir_notification = new bitmap4();
+        // expect the returned notification bitmap to be the same size as requested by client.
+        res.gdir_resok4.gdir_notification = new bitmap4(new int[_args.opgetdeviceinfo.gdia_notify_types.value.length]);
         /*
          * provide faked notification only if client expects them
          */

core/src/test/java/org/dcache/nfs/v4/OperationGETDEVICEINFOTest.java

@@ -0,0 +1,46 @@
+package org.dcache.nfs.v4;
+
+import com.google.common.collect.Sets;
+import java.io.IOException;
+import java.net.URISyntaxException;
+import org.dcache.nfs.v4.xdr.COMPOUND4args;
+import org.dcache.nfs.v4.xdr.COMPOUND4res;
+import org.dcache.nfs.v4.xdr.device_addr4;
+import org.dcache.nfs.v4.xdr.deviceid4;
+import org.dcache.nfs.v4.xdr.layouttype4;
+
+import org.junit.Test;
+
+import static org.dcache.nfs.v4.NfsTestUtils.generateRpcCall;
+import static org.junit.Assert.assertEquals;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.BDDMockito.given;
+
+import static org.dcache.nfs.v4.NfsTestUtils.execute;
+
+/**
+ *
+ */
+public class OperationGETDEVICEINFOTest {
+
+    @Test
+    public void testNotificationBitmapSize() throws IOException, URISyntaxException {
+
+        NFSv41DeviceManager dm = mock(NFSv41DeviceManager.class);
+        given(dm.getDeviceInfo(any(), any())).willReturn(mock(device_addr4.class));
+
+        given(dm.getLayoutTypes()).willReturn(Sets.newHashSet(layouttype4.values()));
+        CompoundContext context = new CompoundContextBuilder()
+                .withDeviceManager(dm)
+                .withCall(generateRpcCall())
+                .build();
+
+        COMPOUND4args gdiArgs = new CompoundBuilder()
+            .withGetdeviceinfo(new deviceid4(new byte[] {0x7}))
+            .build();
+
+        COMPOUND4res res = execute(context, gdiArgs);
+        assertEquals("invalid notification bitmap size", 1, res.resarray.get(0).opgetdeviceinfo.gdir_resok4.gdir_notification.value.length);
+    }
+}