NFS add callback_ops to nfs4_proc_bind_conn_to_session_callback

Fix oops when NULL callback_ops pointer accessed in rpc_init_task
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/nfs4proc.c

@@ -6782,6 +6782,15 @@ nfs41_same_server_scope(struct nfs41_server_scope *a,
 	return false;
 }
 
+static void
+nfs4_bind_one_conn_to_session_done(struct rpc_task *task, void *calldata)
+{
+}
+
+static const struct rpc_call_ops nfs4_bind_one_conn_to_session_ops = {
+	.rpc_call_done =  &nfs4_bind_one_conn_to_session_done,
+};
+
 /*
  * nfs4_proc_bind_one_conn_to_session()
  *
@@ -6810,6 +6819,7 @@ int nfs4_proc_bind_one_conn_to_session(struct rpc_clnt *clnt,
 	struct rpc_task_setup task_setup_data = {
 		.rpc_client = clnt,
 		.rpc_xprt = xprt,
+		.callback_ops = &nfs4_bind_one_conn_to_session_ops,
 		.rpc_message = &msg,
 		.flags = RPC_TASK_TIMEOUT,
 	};