Am 25.07.2013 um 16:23 hat Paolo Bonzini geschrieben:
> Alternatively, this could use a "discard zeroes data" flag returned
> by bdrv_get_info.
>
> Reviewed-by: Eric Blake <ebl...@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
> block.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/block.c b/block.c
> index 7cfbf71..fc1da56 100644
> --- a/block.c
> +++ b/block.c
> @@ -2991,6 +2991,7 @@ static int64_t coroutine_fn
> bdrv_co_get_block_status(BlockDriverState *bs,
> int nb_sectors, int
> *pnum)
> {
> int64_t n;
> + int64_t ret;
>
> if (sector_num >= bs->total_sectors) {
> *pnum = 0;
> @@ -3007,7 +3008,12 @@ static int64_t coroutine_fn
> bdrv_co_get_block_status(BlockDriverState *bs,
> return BDRV_BLOCK_DATA;
> }
>
> - return bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors,
> pnum);
> + ret = bs->drv->bdrv_co_get_block_status(bs, sector_num, nb_sectors,
> pnum);
I think here you should check for ret < 0 before modifying bits.
> + if (!(ret & BDRV_BLOCK_DATA) && bdrv_has_zero_init(bs)) {
> + ret |= BDRV_BLOCK_ZERO;
> + }
> +
> + return ret;
> }
Kevin
