[sheepdog] [PATCH v2 2/7] sheep: make gateway to retry when received SD_RES_OLD_NODE_VER

[Christoph Hellwig]

Oh ok - this patch changes things enough that we can't do what I
proposed in the previous mail.

> +		switch (req->rp.result) {
> +		case SD_RES_OLD_NODE_VER:
> +			/* retry as gateway. */
> +			req->rq.epoch = sys->epoch;
> +			put_vnode_info(req->vnodes);
> +			req->vnodes = get_vnode_info();
> +			setup_access_to_local_objects(req);

Can you add a helper to share this code with gateway_op_done?  Having
this in a properly named helper also helps with self-documenting the
code.

> +		case SD_RES_NEW_NODE_VER:
> +			list_del(&req->request_list);
> +			list_add_tail(&req->request_list, &sys->request_queue);
> +			process_request_event_queues();
> +			break;
> +		default:

We're probably still better off calling process_request_event_queues
once after the loop instead of possibly starting to queue and complete
I/O from inside the loop.  resume_pending_requests already does that
variant, although I think it has a bug because it only checks for a
non-emptry request_queue but not the event queue.