21.09.2020 17:30, Alberto Garcia wrote:
If a BlockDriverState supports backing files but has none then any
unallocated area reads back as zeroes.
bdrv_co_block_status() is only reporting this is if want_zero is true,
but this is an inexpensive test and there is no reason not to do it in
all cases.
Suggested-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
Signed-off-by: Alberto Garcia <be...@igalia.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
---
block/io.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/block/io.c b/block/io.c
index a2389bb38c..ef1ea806e8 100644
--- a/block/io.c
+++ b/block/io.c
@@ -2391,17 +2391,17 @@ static int coroutine_fn
bdrv_co_block_status(BlockDriverState *bs,
if (ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) {
ret |= BDRV_BLOCK_ALLOCATED;
- } else if (want_zero && bs->drv->supports_backing) {
+ } else if (bs->drv->supports_backing) {
BlockDriverState *cow_bs = bdrv_cow_bs(bs);
- if (cow_bs) {
+ if (!cow_bs) {
+ ret |= BDRV_BLOCK_ZERO;
+ } else if (want_zero) {
int64_t size2 = bdrv_getlength(cow_bs);
if (size2 >= 0 && offset >= size2) {
ret |= BDRV_BLOCK_ZERO;
}
- } else {
- ret |= BDRV_BLOCK_ZERO;
}
}
--
Best regards,
Vladimir
