Re: [Qemu-devel] [PATCH v1 1/3] block: block: introduce bdrv_io_plug() and bdrv_io_unplug()

[Ming Lei]

On Tue, Jul 1, 2014 at 12:18 AM, Paolo Bonzini <address@hidden> wrote:
> Il 30/06/2014 18:15, Ming Lei ha scritto:
>
>>>> >> +int bdrv_io_unplug(BlockDriverState *bs)
>>>> >> +{
>>>> >> +    BlockDriver *drv = bs->drv;
>>>> >> +    if (drv && drv->bdrv_io_unplug) {
>>>> >> +        return drv->bdrv_io_unplug(bs);
>>>> >> +    } else if (bs->file) {
>>>> >> +        return bdrv_io_unplug(bs->file);
>>>> >> +    }
>>>> >> +    return 0;
>>>
>>> >
>>> >
>>> > I think this should return void (and that's how you use it in patch 3
>>> > indeed).  If you fix this you can add my Reviewed-by tag.
>>
>> It can be used to trace how many IO are submitted at batch,
>> otherwise device can't know this information at all.
>
>
> Having a return value however suggests that bdrv_io_unplug can fail.  So
> this should be documented.  For now, I'd prefer to keep it simple.

Fair enough, will change it to void in v2.

Thanks,
--
Ming Lei