diff options
| -rw-r--r-- | block/snapshot.c | 30 |
1 files changed, 10 insertions, 20 deletions
diff --git a/block/snapshot.c b/block/snapshot.c index d6f53c3065..75e8d3a937 100644 --- a/block/snapshot.c +++ b/block/snapshot.c @@ -161,21 +161,14 @@ bool bdrv_snapshot_find_by_id_and_name(BlockDriverState *bs, static BdrvChild **bdrv_snapshot_fallback_ptr(BlockDriverState *bs) { BdrvChild **fallback; - BdrvChild *child; + BdrvChild *child = bdrv_primary_child(bs); - /* - * The only BdrvChild pointers that are safe to modify (and which - * we can thus return a reference to) are bs->file and - * bs->backing. - */ - fallback = &bs->file; - if (!*fallback && bs->drv && bs->drv->is_filter) { - fallback = &bs->backing; - } - - if (!*fallback) { + /* We allow fallback only to primary child */ + if (!child) { return NULL; } + fallback = (child == bs->file ? &bs->file : &bs->backing); + assert(*fallback == child); /* * Check that there are no other children that would need to be @@ -309,15 +302,12 @@ int bdrv_snapshot_goto(BlockDriverState *bs, } /* - * fallback_ptr is &bs->file or &bs->backing. *fallback_ptr - * was closed above and set to NULL, but the .bdrv_open() call - * has opened it again, because we set the respective option - * (with the qdict_put_str() call above). - * Assert that .bdrv_open() has attached some child on - * *fallback_ptr, and that it has attached the one we wanted - * it to (i.e., fallback_bs). + * fallback was a primary child. It was closed above and set to NULL, + * but the .bdrv_open() call has opened it again, because we set the + * respective option (with the qdict_put_str() call above). + * Assert that .bdrv_open() has attached the right BDS as primary child. */ - assert(*fallback_ptr && fallback_bs == (*fallback_ptr)->bs); + assert(bdrv_primary_bs(bs) == fallback_bs); bdrv_unref(fallback_bs); return ret; } |