Now block-copy detects fleecing scheme and do write-unchanged operations if detected. So, let's require appropriate permissions.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> --- block/copy-before-write.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/block/copy-before-write.c b/block/copy-before-write.c index 2cd68b480a..808e8707ed 100644 --- a/block/copy-before-write.c +++ b/block/copy-before-write.c @@ -113,6 +113,14 @@ static void cbw_refresh_filename(BlockDriverState *bs) bs->file->bs->filename); } +static bool cbw_is_fleecing(BlockDriverState *bs) +{ + BDRVCopyBeforeWriteState *s = bs->opaque; + + return bs->file && s->target && + bdrv_skip_filters(bs) == bdrv_backing_chain_next(s->target->bs); +} + static void cbw_child_perm(BlockDriverState *bs, BdrvChild *c, BdrvChildRole role, BlockReopenQueue *reopen_queue, @@ -129,7 +137,8 @@ static void cbw_child_perm(BlockDriverState *bs, BdrvChild *c, * only upfront. */ *nshared = BLK_PERM_ALL & ~BLK_PERM_RESIZE; - *nperm = BLK_PERM_WRITE; + *nperm = + cbw_is_fleecing(bs) ? BLK_PERM_WRITE_UNCHANGED : BLK_PERM_WRITE; } else { /* Source child */ bdrv_default_perms(bs, c, role, reopen_queue, -- 2.29.2