Re: [RFC v5 07/11] config: add check to block layer

[Stefan Hajnoczi]

On Sun, 31 Jul 2022 at 21:39, Sam Li <faithilikerun@gmail.com> wrote:
>
> Putting zoned/non-zoned BlockDrivers on top of each other is not
> allowed.
>
> Signed-off-by: Sam Li <faithilikerun@gmail.com>
> ---
>  block.c                          | 13 +++++++++++++
>  block/file-posix.c               |  2 ++
>  block/raw-format.c               |  1 +
>  include/block/block_int-common.h | 10 ++++++++++
>  4 files changed, 26 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;
> +    }
> +
>      if (!QLIST_EMPTY(&child_bs->parents)) {
>          error_setg(errp, "The node %s already has a parent",
>                     child_bs->node_name);
> diff --git a/block/file-posix.c b/block/file-posix.c
> index 6c045eb6e8..8eb0b7bc9b 100644
> --- a/block/file-posix.c
> +++ b/block/file-posix.c
> @@ -4023,6 +4023,8 @@ static BlockDriver bdrv_zoned_host_device = {
>          .format_name = "zoned_host_device",
>          .protocol_name = "zoned_host_device",
>          .instance_size = sizeof(BDRVRawState),
> +        .is_zoned = true,
> +        .supports_zoned_children = true,

zoned_host_device never has children, so supports_zoned_children
should not be set.

>          .bdrv_needs_filename = true,
>          .bdrv_probe_device  = hdev_probe_device,
>          .bdrv_parse_filename = zoned_host_device_parse_filename,
> diff --git a/block/raw-format.c b/block/raw-format.c
> index 6b20bd22ef..9441536819 100644
> --- a/block/raw-format.c
> +++ b/block/raw-format.c
> @@ -614,6 +614,7 @@ static void raw_child_perm(BlockDriverState *bs, 
> BdrvChild *c,
>  BlockDriver bdrv_raw = {
>      .format_name          = "raw",
>      .instance_size        = sizeof(BDRVRawState),
> +    .supports_zoned_children = true,
>      .bdrv_probe           = &raw_probe,
>      .bdrv_reopen_prepare  = &raw_reopen_prepare,
>      .bdrv_reopen_commit   = &raw_reopen_commit,
> diff --git a/include/block/block_int-common.h 
> b/include/block/block_int-common.h
> index de44c7b6f4..0476cd0491 100644
> --- a/include/block/block_int-common.h
> +++ b/include/block/block_int-common.h
> @@ -126,6 +126,16 @@ struct BlockDriver {
>       */
>      bool is_format;
>
> +    /*
> +     * Set to true if the BlockDriver is a zoned block driver.
> +     */
> +    bool is_zoned;
> +
> +    /*
> +     * Set to true if the BlockDriver supports zoned children.
> +     */
> +    bool supports_zoned_children;
> +
>      /*
>       * Drivers not implementing bdrv_parse_filename nor bdrv_open should have
>       * this field set to true, except ones that are defined only by their
> --
> 2.37.1
>
>