Re: [PATCHv2 4/6] osd_client, rbd: update event interface for watch/notify2

[David Disseldorp <ddiss@suse.de>]

Hi Douglas,

Do you still plan on getting these changes upstream? I have one comment
on this patch:

On Wed, 17 Jun 2015 07:25:54 -0700, Douglas Fuller wrote:

> +static void rbd_watch_error_cb(void *arg, u64 cookie, int err)
> +{
> +	struct rbd_device *rbd_dev = (struct rbd_device *)arg;
> +	int ret;
> +
> +	dout("%s: watch error %d on cookie %llu\n", rbd_dev->header_name,
> +		err, cookie);
> +	rbd_warn(rbd_dev, "%s: watch error %d on cookie %llu\n",
> +	         rbd_dev->header_name, err, cookie);
> +
> +	/* reset watch */
> +	rbd_dev_header_unwatch_sync(rbd_dev);
> +	ret = rbd_dev_header_watch_sync(rbd_dev);
> +	rbd_dev_refresh(rbd_dev);
> +	if (ret)
> +		rbd_warn(rbd_dev, "refresh failed: %d", ret);
> +}

The watch reset here could potentially race with the
rbd_dev_header_unwatch_sync() performed on unmap. To handle this,
notify_wq should be stopped prior to unwatch in do_rbd_remove().

Cheers, David