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qcow2: Report BDRV_BLOCK_ZERO more accurately in bdrv_co_block_status() 

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 <vsementsov@virtuozzo.com>
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <66fa0914a0e2b727ab6d1b63ca773d7cd29a9a9e.1603731354.git.berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Alberto Garcia 2020-10-26 17:58:26 +01:00 committed by Kevin Wolf
parent 0c8c4895a6
commit d40f4a565a
1 changed files with 4 additions and 4 deletions
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8
block/io.c
View File

@ -2282,17 +2282,17 @@ 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;
}
}