Re: [PATCH v6 6/8] config: add check to block layer

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Fri, Aug 05, 2022 at 03:57:49PM +0800, Sam Li wrote:
> Putting zoned/non-zoned BlockDrivers on top of each other is not
> allowed.
> 
> Signed-off-by: Sam Li <faithilikerun@gmail.com>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>  block.c                          | 13 +++++++++++++
>  block/file-posix.c               |  1 +
>  block/raw-format.c               |  1 +
>  include/block/block_int-common.h | 10 ++++++++++
>  4 files changed, 25 insertions(+)
> 
> diff --git a/block.c b/block.c
> index bc85f46eed..8a259b158c 100644
> --- a/block.c
> +++ b/block.c
> @@ -7947,6 +7947,19 @@ void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
>          return;
>      }
>  
> +    /*
> +     * Non-zoned block drivers do not follow zoned storage constraints
> +     * (i.e. sequential writes to zones). Refuse mixing zoned and non-zoned
> +     * drivers in a graph.
> +     */
> +    if (!parent_bs->drv->supports_zoned_children && child_bs->drv->is_zoned) {
> +        error_setg(errp, "Cannot add a %s child to a %s parent",
> +                   child_bs->drv->is_zoned ? "zoned" : "non-zoned",
> +                   parent_bs->drv->supports_zoned_children ?
> +                   "support zoned children" : "not support zoned children");
> +        return;
> +    }

This doesn't handle the case where a filter node (like I/O throttling)
is inserted above a raw block driver with a zoned_host_device child.

Can we replace child_bs->drv->is_zoned with child_bs->bl.zoned ==
BLK_Z_HM? I think the is_zoned field is unnecessary.

That way the block/raw-format.c .bdrv_refresh_limits() function can
propagate its child's zone block limits (including the zone model) and
this check will work correctly.

Stefan

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