In many cases we just want to know whether a BDS has at least one BB attached, without needing to know the exact BB that is attached. In contrast to bs->blk, this is still a valid question when more than one BB can be attached, so just answer it by checking the parents list.
Signed-off-by: Kevin Wolf <kw...@redhat.com> Reviewed-by: Max Reitz <mre...@redhat.com> --- block/block-backend.c | 17 +++++++++++++++++ include/sysemu/block-backend.h | 1 + 2 files changed, 18 insertions(+) diff --git a/block/block-backend.c b/block/block-backend.c index 8d6fc77..9dcac97 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -395,6 +395,23 @@ BlockDriverState *blk_bs(BlockBackend *blk) } /* + * Returns true if @bs has an associated BlockBackend. + */ +bool bdrv_has_blk(BlockDriverState *bs) +{ + BdrvChild *child; + QLIST_FOREACH(child, &bs->parents, next_parent) { + if (child->role == &child_root) { + assert(bs->blk); + return true; + } + } + + assert(!bs->blk); + return false; +} + +/* * Return @blk's DriveInfo if any, else null. */ DriveInfo *blk_legacy_dinfo(BlockBackend *blk) diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h index 79f39b8..44a222d 100644 --- a/include/sysemu/block-backend.h +++ b/include/sysemu/block-backend.h @@ -99,6 +99,7 @@ BlockBackend *blk_by_public(BlockBackendPublic *public); BlockDriverState *blk_bs(BlockBackend *blk); void blk_remove_bs(BlockBackend *blk); void blk_insert_bs(BlockBackend *blk, BlockDriverState *bs); +bool bdrv_has_blk(BlockDriverState *bs); void blk_set_allow_write_beyond_eof(BlockBackend *blk, bool allow); void blk_iostatus_enable(BlockBackend *blk); -- 1.8.3.1