fs/afs/callback: Remove deprecated create_singlethread_workqueue

The workqueue "afs_callback_update_worker" queues multiple work items
viz  &vnode->cb_broken_work, &server->cb_break_work which require strict
execution ordering. Hence, an ordered dedicated workqueue has been used.

Since the workqueue is being used on a memory reclaim path, WQ_MEM_RECLAIM
has been set to ensure forward progress under memory pressure.
Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>

fs/afs/callback.c

@@ -461,8 +461,8 @@ static void afs_callback_updater(struct work_struct *work)
  */
 int __init afs_callback_update_init(void)
 {
-	afs_callback_update_worker =
-		create_singlethread_workqueue("kafs_callbackd");
+	afs_callback_update_worker = alloc_ordered_workqueue("kafs_callbackd",
+							     WQ_MEM_RECLAIM);
 	return afs_callback_update_worker ? 0 : -ENOMEM;
 }