Now that the backing file child role implements .attach/.detach callbacks, nothing prevents us from modifying the graph even if that involves changing backing file links.
Signed-off-by: Kevin Wolf <kw...@redhat.com> --- block.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/block.c b/block.c index ff328f1..8224dde 100644 --- a/block.c +++ b/block.c @@ -2788,9 +2788,9 @@ static void change_parent_backing_link(BlockDriverState *from, continue; } if (c->role == &child_backing) { - /* @from is generally not allowed to be a backing file, except for - * when @to is the overlay. In that case, @from may not be replaced - * by @to as @to's backing node. */ + /* If @from is a backing file of @to, ignore the child to avoid + * creating a loop. We only want to change the pointer of other + * parents. */ QLIST_FOREACH(to_c, &to->children, next) { if (to_c == c) { break; @@ -2801,7 +2801,6 @@ static void change_parent_backing_link(BlockDriverState *from, } } - assert(c->role != &child_backing); bdrv_ref(to); bdrv_replace_child(c, to); bdrv_unref(from); -- 1.8.3.1