| Message ID | 1379067909-22984-13-git-send-email-pl@kamp.de |
|---|---|
| State | New |
| Headers | show |
On 09/13/2013 04:25 AM, Peter Lieven wrote: > this patch does 2 things: > a) only do additional call outs if BDRV_BLOCK_ZERO is not already set. > b) use bdi.discard_zeroes to return the zero state of an unallocated block. > the callout to bdrv_has_zero_init() is only valid right after bdrv_create. > > Signed-off-by: Peter Lieven <pl@kamp.de> > --- > block.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/block.c b/block.c > index 282943b..6698c10 100644 > --- a/block.c > +++ b/block.c > @@ -3153,8 +3153,10 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, > return ret; > } > > - if (!(ret & BDRV_BLOCK_DATA)) { > - if (bdrv_has_zero_init(bs)) { > + if (!(ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO)) { Why not avoid the &&: if ((ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) == 0) { Then again, any decent compiler will probably already do that optimization on your behalf. > + BlockDriverInfo bdi; > + if (bdrv_get_info(bs, &bdi) == 0 && > + bdi.discard_zeroes) { > ret |= BDRV_BLOCK_ZERO; > } else if (bs->backing_hd) { > BlockDriverState *bs2 = bs->backing_hd; >
On 13.09.2013 12:25, Peter Lieven wrote: > this patch does 2 things: > a) only do additional call outs if BDRV_BLOCK_ZERO is not already set. > b) use bdi.discard_zeroes to return the zero state of an unallocated block. > the callout to bdrv_has_zero_init() is only valid right after bdrv_create. > > Signed-off-by: Peter Lieven <pl@kamp.de> > --- > block.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/block.c b/block.c > index 282943b..6698c10 100644 > --- a/block.c > +++ b/block.c > @@ -3153,8 +3153,10 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, > return ret; > } > > - if (!(ret & BDRV_BLOCK_DATA)) { > - if (bdrv_has_zero_init(bs)) { > + if (!(ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO)) { > + BlockDriverInfo bdi; > + if (bdrv_get_info(bs, &bdi) == 0 && > + bdi.discard_zeroes) { > ret |= BDRV_BLOCK_ZERO; > } else if (bs->backing_hd) { > BlockDriverState *bs2 = bs->backing_hd; Kevin, according to your comment that we need a separate function like bdrv_has_discard_zeroes. It should also be ok to change the order and first check for bs->backing_hd here or not? Peter
diff --git a/block.c b/block.c index 282943b..6698c10 100644 --- a/block.c +++ b/block.c @@ -3153,8 +3153,10 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, return ret; } - if (!(ret & BDRV_BLOCK_DATA)) { - if (bdrv_has_zero_init(bs)) { + if (!(ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO)) { + BlockDriverInfo bdi; + if (bdrv_get_info(bs, &bdi) == 0 && + bdi.discard_zeroes) { ret |= BDRV_BLOCK_ZERO; } else if (bs->backing_hd) { BlockDriverState *bs2 = bs->backing_hd;
this patch does 2 things: a) only do additional call outs if BDRV_BLOCK_ZERO is not already set. b) use bdi.discard_zeroes to return the zero state of an unallocated block. the callout to bdrv_has_zero_init() is only valid right after bdrv_create. Signed-off-by: Peter Lieven <pl@kamp.de> --- block.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)