+static struct workqueue_struct *callback_wq;
+
+int nfsd4_create_callback_queue(void)
+{
+ callback_wq = create_singlethread_workqueue("nfsd4_callbacks");
+ if (!callback_wq)
+ return -ENOMEM;
+ return 0;
+}
+
+void nfsd4_destroy_callback_queue(void)
+{
+ destroy_workqueue(callback_wq);
+}
+
+void nfsd4_set_callback_client(struct nfs4_client *clp, struct rpc_clnt
+*new)
+{
+ struct rpc_clnt *old = clp->cl_cb_client;
+
+ clp->cl_cb_client = new;
+ /*
+ * After this, any work that saw the old value of cl_cb_client will
+ * be gone:
+ */
+ flush_workqueue(callback_wq);
+ /* So we can safely shut it down: */
+ if (old)
+ rpc_shutdown_client(old);
+}
+