[01/11] block: generalize BlockLimits handling to cover bdrv_aio_discard too

bdrv_co_discard is only covering drivers which have a .bdrv_co_discard()
implementation, but not those with .bdrv_aio_discard(). Not very nice,
and easy to avoid.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block.c | 80 +++++++++++++++++++++++++++++++++--------------------------------
 1 file changed, 41 insertions(+), 39 deletions(-)

Am 12.11.2013 um 16:49 schrieb Paolo Bonzini <pbonzini@redhat.com>:

> bdrv_co_discard is only covering drivers which have a .bdrv_co_discard()
> implementation, but not those with .bdrv_aio_discard(). Not very nice,
> and easy to avoid.
> 
> Suggested-by: Kevin Wolf <kwolf@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> block.c | 80 +++++++++++++++++++++++++++++++++--------------------------------
> 1 file changed, 41 insertions(+), 39 deletions(-)
> 
> diff --git a/block.c b/block.c
> index aba6a19..ba6872e 100644
> --- a/block.c
> +++ b/block.c
> @@ -4281,6 +4281,8 @@ static void coroutine_fn bdrv_discard_co_entry(void *opaque)
> int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
>                                  int nb_sectors)
> {
> +    int max_discard;
> +
>     if (!bs->drv) {
>         return -ENOMEDIUM;
>     } else if (bdrv_check_request(bs, sector_num, nb_sectors)) {
> @@ -4298,55 +4300,55 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
>         return 0;
>     }
> 
> -    if (bs->drv->bdrv_co_discard) {
> -        int max_discard = bs->bl.max_discard ?
> -                          bs->bl.max_discard : MAX_DISCARD_DEFAULT;
> +    if (!bs->drv->bdrv_co_discard && !bs->drv->bdrv_aio_discard) {
> +        return 0;
> +    }
> 
> -        while (nb_sectors > 0) {
> -            int ret;
> -            int num = nb_sectors;
> +    max_discard = bs->bl.max_discard ?  bs->bl.max_discard : MAX_DISCARD_DEFAULT;
> +    while (nb_sectors > 0) {
> +        int ret;
> +        int num = nb_sectors;
> 
> -            /* align request */
> -            if (bs->bl.discard_alignment &&
> -                num >= bs->bl.discard_alignment &&
> -                sector_num % bs->bl.discard_alignment) {
> -                if (num > bs->bl.discard_alignment) {
> -                    num = bs->bl.discard_alignment;
> -                }
> -                num -= sector_num % bs->bl.discard_alignment;
> +        /* align request */
> +        if (bs->bl.discard_alignment &&
> +            num >= bs->bl.discard_alignment &&
> +            sector_num % bs->bl.discard_alignment) {
> +            if (num > bs->bl.discard_alignment) {
> +                num = bs->bl.discard_alignment;
>             }
> +            num -= sector_num % bs->bl.discard_alignment;
> +        }
> 
> -            /* limit request size */
> -            if (num > max_discard) {
> -                num = max_discard;
> -            }
> +        /* limit request size */
> +        if (num > max_discard) {
> +            num = max_discard;
> +        }
> 
> +        if (bs->drv->bdrv_co_discard) {
>             ret = bs->drv->bdrv_co_discard(bs, sector_num, num);
> -            if (ret) {
> -                return ret;
> +        } else {
> +            BlockDriverAIOCB *acb;
> +            CoroutineIOCompletion co = {
> +                .coroutine = qemu_coroutine_self(),
> +            };
> +
> +            acb = bs->drv->bdrv_aio_discard(bs, sector_num, nb_sectors,
> +                                            bdrv_co_io_em_complete, &co);
> +            if (acb == NULL) {
> +                return -EIO;
> +            } else {
> +                qemu_coroutine_yield();
> +                ret = co.ret;
>             }
> -
> -            sector_num += num;
> -            nb_sectors -= num;
>         }
> -        return 0;
> -    } else if (bs->drv->bdrv_aio_discard) {
> -        BlockDriverAIOCB *acb;
> -        CoroutineIOCompletion co = {
> -            .coroutine = qemu_coroutine_self(),
> -        };
> -
> -        acb = bs->drv->bdrv_aio_discard(bs, sector_num, nb_sectors,
> -                                        bdrv_co_io_em_complete, &co);
> -        if (acb == NULL) {
> -            return -EIO;
> -        } else {
> -            qemu_coroutine_yield();
> -            return co.ret;
> +        if (ret) {
> +            return ret;
>         }
> -    } else {
> -        return 0;
> +
> +        sector_num += num;
> +        nb_sectors -= num;
>     }
> +    return 0;
> }
> 
> int bdrv_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors)
> -- 
> 1.8.4.2
> 
> 


Thank you.

Reviewed-By: Peter Lieven <pl@kamp.de>