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 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. > + */ > + > + 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