[Sheepdog] [PATCH] sheep: fix race on sys->pending_list

[Christoph Hellwig]

On Tue, May 08, 2012 at 05:21:40PM +0800, Yunkai Zhang wrote:
> From: Yunkai Zhang <qiushu.zyk at taobao.com>
> 
> Actually, there are two race problems when we call do_cluster_request()
> in IO threads:
> 1) race on sys->pending_list which would also be updated in sd_notify_handler().
> 2) calling sys->notify() in IO threads other than main thread is also
>    mistake.
> 
> So I move do_cluster_request() into cluster_op_done().

What the reason to bother with a workqueue if you could call it
directly?

> @@ -174,6 +174,7 @@ static void local_op_done(struct work *work)
>  static void cluster_op_done(struct work *work)
>  {
>  	/* request is forwarded to cpg group */
> +	do_cluster_request(work);
>  }

Also is there any good reason to have the wrapper here?  The comment
doesn't seem very helpful anymore either.