13.06.2019 15:33, Max Reitz wrote: > On 13.06.19 14:26, Vladimir Sementsov-Ogievskiy wrote: >> 13.06.2019 1:09, Max Reitz wrote: >>> Add some helper functions for skipping filters in a chain of block >>> nodes. >>> >>> Signed-off-by: Max Reitz <mre...@redhat.com> >>> --- >>> include/block/block_int.h | 3 +++ >>> block.c | 55 +++++++++++++++++++++++++++++++++++++++ >>> 2 files changed, 58 insertions(+) >>> >>> diff --git a/include/block/block_int.h b/include/block/block_int.h >>> index 7ce71623f8..875a33f255 100644 >>> --- a/include/block/block_int.h >>> +++ b/include/block/block_int.h >>> @@ -1264,6 +1264,9 @@ BdrvChild *bdrv_filtered_child(BlockDriverState *bs); >>> BdrvChild *bdrv_metadata_child(BlockDriverState *bs); >>> BdrvChild *bdrv_storage_child(BlockDriverState *bs); >>> BdrvChild *bdrv_primary_child(BlockDriverState *bs); >>> +BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs); >>> +BlockDriverState *bdrv_skip_rw_filters(BlockDriverState *bs); >>> +BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs); >>> >>> static inline BlockDriverState *child_bs(BdrvChild *child) >>> { >>> diff --git a/block.c b/block.c >>> index 724d8889a6..be18130944 100644 >>> --- a/block.c >>> +++ b/block.c >>> @@ -6494,3 +6494,58 @@ BdrvChild *bdrv_primary_child(BlockDriverState *bs) >>> { >>> return bdrv_filtered_rw_child(bs) ?: bs->file; >>> } >>> + >>> +static BlockDriverState *bdrv_skip_filters(BlockDriverState *bs, >>> + bool stop_on_explicit_filter) >>> +{ >>> + BdrvChild *filtered; >>> + >>> + if (!bs) { >>> + return NULL; >>> + } >>> + >>> + while (!(stop_on_explicit_filter && !bs->implicit)) { >>> + filtered = bdrv_filtered_rw_child(bs); >>> + if (!filtered) { >>> + break; >>> + } >>> + bs = filtered->bs; >>> + } >>> + /* >>> + * Note that this treats nodes with bs->drv == NULL >> >> as well as filters without filtered_rw child > > A filter always must have a filtered_rw child, though. So I don’t quite > understand what you mean here... > > Max > >> as not being >>> + * R/W filters (bs->drv == NULL should be replaced by something >>> + * else anyway). >>> + * The advantage of this behavior is that this function will thus >>> + * always return a non-NULL value (given a non-NULL @bs). >> >> and this is the advantage of what I've written, not about bs->drv.
I mean, that advantage seems unrelated to the reason about bs->drv == NULL, as even with bs->drv == NULL we can go to bs->backing or bs->file.. But I don't really care, my r-b stays here anyway >> >>> + */ >>> + >>> + return bs; >>> +} >>> + >>> +/* >>> + * Return the first BDS that has not been added implicitly or that >>> + * does not have an RW-filtered child down the chain starting from @bs >>> + * (including @bs itself). >>> + */ >>> +BlockDriverState *bdrv_skip_implicit_filters(BlockDriverState *bs) >>> +{ >>> + return bdrv_skip_filters(bs, true); >>> +} >>> + >>> +/* >>> + * Return the first BDS that does not have an RW-filtered child down >>> + * the chain starting from @bs (including @bs itself). >>> + */ >>> +BlockDriverState *bdrv_skip_rw_filters(BlockDriverState *bs) >>> +{ >>> + return bdrv_skip_filters(bs, false); >>> +} >>> + >>> +/* >>> + * For a backing chain, return the first non-filter backing image of >>> + * the first non-filter image. >>> + */ >>> +BlockDriverState *bdrv_backing_chain_next(BlockDriverState *bs) >>> +{ >>> + return >>> bdrv_skip_rw_filters(bdrv_filtered_cow_bs(bdrv_skip_rw_filters(bs))); >>> +} >>> >> >> >> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com> >> > > -- Best regards, Vladimir