NLM/lockd: Ensure that nlmclnt_cancel() returns results of the CANCEL call

Currently, it returns success as long as the RPC call was sent. We'd like
to know if the CANCEL operation succeeded on the server.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/lockd/clntproc.c

@@ -699,6 +699,10 @@ static const struct rpc_call_ops nlmclnt_unlock_ops = {
 static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 {
 	struct nlm_rqst	*req;
+	int status;
+
+	dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
+		"       Attempting to cancel lock.\n");
 
 	req = nlm_alloc_call(nlm_get_host(host));
 	if (!req)
@@ -708,7 +712,12 @@ static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl
 	nlmclnt_setlockargs(req, fl);
 	req->a_args.block = block;
 
-	return nlmclnt_async_call(req, NLMPROC_CANCEL, &nlmclnt_cancel_ops);
+	atomic_inc(&req->a_count);
+	status = nlmclnt_async_call(req, NLMPROC_CANCEL, &nlmclnt_cancel_ops);
+	if (status == 0 && req->a_res.status == nlm_lck_denied)
+		status = -ENOLCK;
+	nlm_release_call(req);
+	return status;
 }
 
 static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)