Re: [PATCH v7 01/47] block: Add child access functions

[Vladimir Sementsov-Ogievskiy]

25.06.2020 18:21, Max Reitz wrote:
> There are BDS children that the general block layer code can access,
> namely bs->file and bs->backing.  Since the introduction of filters and
> external data files, their meaning is not quite clear.  bs->backing can
> be a COW source, or it can be a filtered child; bs->file can be a
> filtered child, it can be data and metadata storage, or it can be just
> metadata storage.
>
> This overloading really is not helpful.  This patch adds functions that
> retrieve the correct child for each exact purpose.  Later patches in
> this series will make use of them.  Doing so will allow us to handle
> filter nodes in a meaningful way.
>
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   include/block/block_int.h | 44 +++++++++++++++++--
>   block.c                   | 90 +++++++++++++++++++++++++++++++++++++++
>   2 files changed, 131 insertions(+), 3 deletions(-)
>
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 1b86b59af1..bb3457c5e8 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h

[..]

> +/*
> + * If @bs acts as a filter for exactly one of its children, return
> + * that child.
> + */
> +BdrvChild *bdrv_filter_child(BlockDriverState *bs)

Hmm you called it filter_child instead of filterED_child..

> +{
> +    BdrvChild *c;
> +
> +    if (!bs || !bs->drv) {
> +        return NULL;
> +    }
> +
> +    if (!bs->drv->is_filter) {
> +        return NULL;
> +    }
> +
> +    /* Only one of @backing or @file may be used */
> +    assert(!(bs->backing && bs->file));
> +
> +    c = bs->backing ?: bs->file;
> +    if (!c) {
> +        return NULL;
> +    }
> +
> +    assert(c->role & BDRV_CHILD_FILTERED);

But the role is still called CHILD_FILTERED

> +    return c;
> +}

(just note that it's a bit inconsistent, keep my r-b anyway)


--
Best regards,
Vladimir