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 <[email protected]>
> ---
> 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 <[email protected]>
--
Best regards,
Vladimir
