Re: [PATCH v11 5/7] config: add check to block layer

[Hannes Reinecke]

On 10/10/22 04:21, 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                          | 17 +++++++++++++++++
>   block/file-posix.c               | 13 +++++++++++++
>   block/raw-format.c               |  1 +
>   include/block/block_int-common.h |  5 +++++
>   4 files changed, 36 insertions(+)
>   mode change 100644 => 100755 block.c
>   mode change 100644 => 100755 block/file-posix.c
>
> diff --git a/block.c b/block.c
> old mode 100644
> new mode 100755
> index bc85f46eed..bf2f2918e7
> --- a/block.c
> +++ b/block.c
> @@ -7947,6 +7947,23 @@ 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 &&
> +        /* The host-aware model allows zoned storage constraints and random
> +         * write. Allow mixing host-aware and non-zoned drivers. Using
> +         * host-aware device as a regular device. */

It's a very unusual style to put comments inside a condition.
Please move it before or after the condition to keep the condition together.

> +        child_bs->bl.zoned == BLK_Z_HM) {
> +        error_setg(errp, "Cannot add a %s child to a %s parent",
> +                   child_bs->bl.zoned == BLK_Z_HM ? "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
> old mode 100644
> new mode 100755
> index 226f5d48f5..a9d347292e
> --- a/block/file-posix.c
> +++ b/block/file-posix.c
> @@ -778,6 +778,19 @@ static int raw_open_common(BlockDriverState *bs, QDict 
> *options,
>               goto fail;
>           }
>       }
> +#ifdef CONFIG_BLKZONED
> +    /*
> +     * The kernel page cache does not reliably work for writes to SWR zones
> +     * of zoned block device because it can not guarantee the order of writes.
> +     */
> +    if (strcmp(bs->drv->format_name, "zoned_host_device") == 0) {
> +        if (!(s->open_flags & O_DIRECT)) {

You can join these conditions with '&&' and safe one level of intendation.

> +            error_setg(errp, "driver=zoned_host_device was specified, but it "
> +                             "requires cache.direct=on, which was not 
> specified.");
> +            return -EINVAL; /* No host kernel page cache */
> +        }
> +    }
> +#endif
>   
>       if (S_ISBLK(st.st_mode)) {
>   #ifdef BLKDISCARDZEROES
> diff --git a/block/raw-format.c b/block/raw-format.c
> index 618c6b1ec2..b885688434 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 cdc06e77a6..37dddc603c 100644
> --- a/include/block/block_int-common.h
> +++ b/include/block/block_int-common.h
> @@ -127,6 +127,11 @@ struct BlockDriver {
>        */
>       bool is_format;
>   
> +    /*
> +     * 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

The remainder looks good.
Once you fixed the minor editing issues you can add:

Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
--
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
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