nfsd4: remove probe task's reference on client

Any null probe rpc will be synchronously destroyed by the
rpc_shutdown_client() in expire_client(), so the rpc task cannot outlast
the nfs4 client.  Therefore there's no need for that task to hold a
reference on the client.
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>

fs/nfsd/nfs4callback.c

@@ -509,7 +509,6 @@ static void nfsd4_cb_probe_done(struct rpc_task *task, void *calldata)
 		warn_no_callback_path(clp, task->tk_status);
 	else
 		atomic_set(&clp->cl_cb_conn.cb_set, 1);
-	put_nfs4_client(clp);
 }
 
 static const struct rpc_call_ops nfsd4_cb_probe_ops = {
@@ -542,10 +541,8 @@ void do_probe_callback(struct nfs4_client *clp)
 	status = rpc_call_async(cb->cb_client, &msg,
 				RPC_TASK_SOFT | RPC_TASK_SOFTCONN,
 				&nfsd4_cb_probe_ops, (void *)clp);
-	if (status) {
+	if (status)
 		warn_no_callback_path(clp, status);
-		put_nfs4_client(clp);
-	}
 }
 
 /*
@@ -563,10 +560,6 @@ nfsd4_probe_callback(struct nfs4_client *clp)
 		warn_no_callback_path(clp, status);
 		return;
 	}
-
-	/* the task holds a reference to the nfs4_client struct */
-	atomic_inc(&clp->cl_count);
-
 	do_probe_callback(clp);
 }