This helper function will find the active (top-most) layer of a specified BDS. This returns either the active layer, or NULL if the passed BDS is NULL.
Signed-off-by: Jeff Cody <jc...@redhat.com> --- block.c | 10 ++++++++++ include/block/block.h | 1 + 2 files changed, 11 insertions(+) diff --git a/block.c b/block.c index b72fe4e..577d4f1 100644 --- a/block.c +++ b/block.c @@ -4379,6 +4379,16 @@ BlockDriverState *bdrv_find_base(BlockDriverState *bs) return curr_bs; } +/* Given a BDS, searches for the active layer. If + * active layer cannot be found, returns NULL */ +BlockDriverState *bdrv_find_active(BlockDriverState *bs) +{ + while (bs && bs->overlay) { + bs = bs->overlay; + } + return bs; +} + /**************************************************************/ /* async I/Os */ diff --git a/include/block/block.h b/include/block/block.h index 4dc68be..a978e0d 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -293,6 +293,7 @@ int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top, BlockDriverState *bdrv_find_overlay(BlockDriverState *active, BlockDriverState *bs); BlockDriverState *bdrv_find_base(BlockDriverState *bs); +BlockDriverState *bdrv_find_active(BlockDriverState *bs); typedef struct BdrvCheckResult { -- 1.8.3.1