Am 30.07.2013 um 17:15 hat Paolo Bonzini geschrieben:
> Il 30/07/2013 16:40, Kevin Wolf ha scritto:
> > 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.
>
> And it is, in patch 15 ("block: use bdrv_has_zero_init to return
> BDRV_BLOCK_ZERO"). :) Should I reorder the patches?
No, I don't mind. I did look at the final state, but I missed it because
I expected something with bs->backing_hd instead of bdrv_has_zero_init()
and didn't remember that the former is already included in the latter.
Kevin
