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qcow2: fix condition in is_zero_cluster

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We should check for (res & BDRV_BLOCK_ZERO) only. The situation when we
will have !(res & BDRV_BLOCK_DATA) and will not have BDRV_BLOCK_ZERO is
not possible for images with bdi.unallocated_blocks_are_zero == true.

For those images where it's false, however, it can happen and we must
not consider the data zeroed then or we would corrupt the image.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Denis V. Lunev 2016-05-17 12:15:42 +03:00 committed by Kevin Wolf
parent b97511c7bc
commit f575f145f4
1 changed files with 1 additions and 1 deletions
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2
block/qcow2.c
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@ -2412,7 +2412,7 @@ static bool is_zero_cluster(BlockDriverState *bs, int64_t start)
BlockDriverState *file;
int64_t res = bdrv_get_block_status_above(bs, NULL, start,
s->cluster_sectors, &nr, &file);
return res >= 0 && ((res & BDRV_BLOCK_ZERO) || !(res & BDRV_BLOCK_DATA));
return res >= 0 && (res & BDRV_BLOCK_ZERO);
}
static bool is_zero_cluster_top_locked(BlockDriverState *bs, int64_t start)