nfs41: add device delete notification

Motivation:
in deployments where devices dynamically added and removed it's often
needed to notify client that data server will never be back. Moreover,
old clients (RHEL6 and clones) keep the connection to data server even
after unmount, however, they respect device delete notifications.

Modification:
Add device delete notification.

Result:
server can notify clients when a device is removed from the system.

Acked-by: Paul Millar
Target: master, 0.17
(cherry picked from commit 6dc4032)
Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2009 - 2016 Deutsches Elektronen-Synchroton,
+ * Copyright (c) 2009 - 2018 Deutsches Elektronen-Synchroton,
  * Member of the Helmholtz Association, (DESY), HAMBURG, GERMANY
  *
  * This library is free software; you can redistribute it and/or modify
@@ -43,9 +43,16 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import org.dcache.nfs.nfsstat;
+import org.dcache.nfs.v4.xdr.CB_NOTIFY_DEVICEID4args;
+import org.dcache.nfs.v4.xdr.bitmap4;
+import org.dcache.nfs.v4.xdr.deviceid4;
 import org.dcache.nfs.v4.xdr.layoutrecall_file4;
 import org.dcache.nfs.v4.xdr.length4;
 import org.dcache.nfs.v4.xdr.nfs_fh4;
+import org.dcache.nfs.v4.xdr.notify4;
+import org.dcache.nfs.v4.xdr.notify_deviceid_delete4;
+import org.dcache.nfs.v4.xdr.notify_deviceid_type4;
+import org.dcache.nfs.v4.xdr.notifylist4;
 import org.dcache.nfs.v4.xdr.offset4;
 import org.dcache.nfs.v4.xdr.stateid4;
 import org.dcache.oncrpc4j.rpc.OncRpcException;
@@ -55,6 +62,7 @@
 import org.dcache.oncrpc4j.rpc.RpcAuthTypeUnix;
 import org.dcache.oncrpc4j.rpc.RpcCall;
 import org.dcache.oncrpc4j.rpc.RpcTransport;
+import org.dcache.oncrpc4j.xdr.Xdr;
 import org.dcache.oncrpc4j.xdr.XdrAble;
 import org.dcache.oncrpc4j.xdr.XdrVoid;
 
@@ -201,4 +209,37 @@ public void cbLayoutRecallFile(nfs_fh4 fh, stateid4 stateid) throws OncRpcExcept
         nfsstat.throwIfNeeded(res.status);
     }
 
+    public void cbDeleteDevice(deviceid4 id) throws OncRpcException, IOException {
+
+        CB_NOTIFY_DEVICEID4args cbDeleteDeciveId = new CB_NOTIFY_DEVICEID4args();
+
+        cbDeleteDeciveId.cnda_changes = new notify4[1];
+        cbDeleteDeciveId.cnda_changes[0] = new notify4();
+        cbDeleteDeciveId.cnda_changes[0].notify_mask = bitmap4.of(notify_deviceid_type4.NOTIFY_DEVICEID4_DELETE);
+
+        notify_deviceid_delete4 deleteDevice = new notify_deviceid_delete4();
+        deleteDevice.ndd_layouttype = layouttype4.LAYOUT4_NFSV4_1_FILES.getValue();
+        deleteDevice.ndd_deviceid = id;
+
+        try (Xdr xdr = new Xdr(32)) {
+
+            xdr.beginEncoding();
+            deleteDevice.xdrEncode(xdr);
+            xdr.endEncoding();
+            byte[] b = xdr.getBytes();
+
+            cbDeleteDeciveId.cnda_changes[0].notify_vals = new notifylist4(b);
+        }
+
+        nfs_cb_argop4 opArgs = new nfs_cb_argop4();
+        opArgs.argop = nfs_cb_opnum4.OP_CB_NOTIFY_DEVICEID;
+        opArgs.opcbnotify_deviceid = cbDeleteDeciveId;
+
+        XdrAble args = generateCompound("cb_delete_device", opArgs);
+
+        CB_COMPOUND4res res = new CB_COMPOUND4res();
+        _rpc.call(nfs4_prot.CB_COMPOUND_1, args, res);
+        nfsstat.throwIfNeeded(res.status);
+    }
+
 }