Am 25.07.2013 um 16:23 hat Paolo Bonzini geschrieben:
> Reviewed-by: Eric Blake <ebl...@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
> block/cow.c | 8 +++++++-
> block/qcow.c | 9 ++++++++-
> block/qcow2.c | 16 ++++++++++++++--
> block/qed.c | 35 ++++++++++++++++++++++++++++-------
> block/sheepdog.c | 2 +-
> block/vdi.c | 13 ++++++++++++-
> block/vmdk.c | 19 ++++++++++++++++++-
> block/vvfat.c | 11 ++++++-----
> 8 files changed, 94 insertions(+), 19 deletions(-)
>
> diff --git a/block/cow.c b/block/cow.c
> index e738b96..1e90413 100644
> --- a/block/cow.c
> +++ b/block/cow.c
> @@ -194,7 +194,13 @@ static int coroutine_fn
> cow_co_is_allocated(BlockDriverState *bs,
> static int64_t coroutine_fn cow_co_get_block_status(BlockDriverState *bs,
> int64_t sector_num, int nb_sectors, int *num_same)
> {
> - return cow_co_is_allocated(bs, sector_num, nb_sectors, num_same);
> + BDRVCowState *s = bs->opaque;
> + int ret = cow_co_is_allocated(bs, sector_num, nb_sectors, num_same);
> + int64_t offset = s->cow_sectors_offset + (sector_num <<
> BDRV_SECTOR_BITS);
> + if (ret < 0) {
> + return ret;
> + }
> + return (ret ? BDRV_BLOCK_DATA : 0) | offset | BDRV_BLOCK_OFFSET_VALID;
> }
>
> static int cow_update_bitmap(BlockDriverState *bs, int64_t sector_num,
> diff --git a/block/qcow.c b/block/qcow.c
> index acd1aeb..1a65822 100644
> --- a/block/qcow.c
> +++ b/block/qcow.c
> @@ -410,7 +410,14 @@ static int64_t coroutine_fn
> qcow_co_get_block_status(BlockDriverState *bs,
> if (n > nb_sectors)
> n = nb_sectors;
> *pnum = n;
> - return (cluster_offset != 0);
> + if (!cluster_offset) {
> + return 0;
If you take your comment in patch 11 serious, you should return
bs->backing_hd ? 0 : BDRV_BLOCK_ZERO instead. (I think it would be
useful behaviour, too, because knowing that a sector is zero enables
optimisations in several places.)
Of course, this is something that could be done in the block.c
implementation of bdrv_co_get_block_status() instead of each single
driver.
Kevin
