Re: [Xen-devel] [PATCH v3] xen-blkfront: dynamic configuration of per-vbd resources

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Jul 27, 2016 at 11:21:25AM +0800, Bob Liu wrote:
[...]
> +static ssize_t dynamic_reconfig_device(struct blkfront_info *info, ssize_t 
> count)
> +{
> +     /*
> +      * Prevent new requests even to software request queue.
> +      */
> +     blk_mq_freeze_queue(info->rq);
> +
> +     /*
> +      * Guarantee no uncompleted reqs.
> +      */

I'm also wondering, why do you need to guarantee that there are no 
uncompleted requests? The resume procedure is going to call blkif_recover 
that will take care of requeuing any unfinished requests that are on the 
ring.

> +     if (part_in_flight(&info->gd->part0) || info->reconfiguring) {
> +             blk_mq_unfreeze_queue(info->rq);
> +             pr_err("Dev:%s busy, please retry later.\n", 
> dev_name(&info->xbdev->dev));
> +             return -EBUSY;
> +     }

Roger.

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