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 <p...@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