Re: [PATCH v8 3/7] block: add block layer APIs resembling Linux ZonedBlockDevice ioctls

[Markus Armbruster <armbru@redhat.com>]

Sam Li <faithilikerun@gmail.com> writes:

> By adding zone management operations in BlockDriver, storage controller
> emulation can use the new block layer APIs including Report Zone and
> four zone management operations (open, close, finish, reset).
>
> Add zoned storage commands of the device: zone_report(zrp), zone_open(zo),
> zone_close(zc), zone_reset(zrs), zone_finish(zf).
>
> For example, to test zone_report, use following command:
> $ ./build/qemu-io --image-opts driver=zoned_host_device, filename=/dev/nullb0
> -c "zrp offset nr_zones"
>
> Signed-off-by: Sam Li <faithilikerun@gmail.com>
> Reviewed-by: Hannes Reinecke <hare@suse.de>

[...]

> diff --git a/block/file-posix.c b/block/file-posix.c
> index 0a8b4b426e..e3efba6db7 100644
> --- a/block/file-posix.c
> +++ b/block/file-posix.c

[...]

> @@ -3752,6 +4025,54 @@ static BlockDriver bdrv_host_device = {
>  #endif
>  };
>  
> +#if defined(CONFIG_BLKZONED)
> +static BlockDriver bdrv_zoned_host_device = {
> +        .format_name = "zoned_host_device",

Indentation should be 4, not 8.

> +        .protocol_name = "zoned_host_device",
> +        .instance_size = sizeof(BDRVRawState),
> +        .bdrv_needs_filename = true,
> +        .bdrv_probe_device  = hdev_probe_device,
> +        .bdrv_file_open     = hdev_open,
> +        .bdrv_close         = raw_close,
> +        .bdrv_reopen_prepare = raw_reopen_prepare,
> +        .bdrv_reopen_commit  = raw_reopen_commit,
> +        .bdrv_reopen_abort   = raw_reopen_abort,
> +        .bdrv_co_create_opts = bdrv_co_create_opts_simple,
> +        .create_opts         = &bdrv_create_opts_simple,
> +        .mutable_opts        = mutable_opts,
> +        .bdrv_co_invalidate_cache = raw_co_invalidate_cache,
> +        .bdrv_co_pwrite_zeroes = hdev_co_pwrite_zeroes,
> +
> +        .bdrv_co_preadv         = raw_co_preadv,
> +        .bdrv_co_pwritev        = raw_co_pwritev,
> +        .bdrv_co_flush_to_disk  = raw_co_flush_to_disk,
> +        .bdrv_co_pdiscard       = hdev_co_pdiscard,
> +        .bdrv_co_copy_range_from = raw_co_copy_range_from,
> +        .bdrv_co_copy_range_to  = raw_co_copy_range_to,
> +        .bdrv_refresh_limits = raw_refresh_limits,
> +        .bdrv_io_plug = raw_aio_plug,
> +        .bdrv_io_unplug = raw_aio_unplug,
> +        .bdrv_attach_aio_context = raw_aio_attach_aio_context,
> +
> +        .bdrv_co_truncate       = raw_co_truncate,
> +        .bdrv_getlength = raw_getlength,
> +        .bdrv_get_info = raw_get_info,
> +        .bdrv_get_allocated_file_size
> +                            = raw_get_allocated_file_size,
> +        .bdrv_get_specific_stats = hdev_get_specific_stats,
> +        .bdrv_check_perm = raw_check_perm,
> +        .bdrv_set_perm   = raw_set_perm,
> +        .bdrv_abort_perm_update = raw_abort_perm_update,
> +        .bdrv_probe_blocksizes = hdev_probe_blocksizes,
> +        .bdrv_probe_geometry = hdev_probe_geometry,
> +        .bdrv_co_ioctl = hdev_co_ioctl,
> +
> +        /* zone management operations */
> +        .bdrv_co_zone_report = raw_co_zone_report,
> +        .bdrv_co_zone_mgmt = raw_co_zone_mgmt,
> +};

Differences to bdrv_host_device:

* .bdrv_parse_filename is not set

* .bdrv_co_ioctl is not set

* .bdrv_co_zone_report and .bdrv_co_zone_mgmt are set

Notably common is .bdrv_file_open = hdev_open.  What happens when you
try to create a zoned_host_device where the @filename argument is not in
fact a zoned device?

Do we really need a separate, but almost identical BlockDriver?  Could
the existing one provide zoned functionality exactly when the underlying
host device does?

Forgive me if these are ignorant questions, or have been discussed
before.

> +#endif
> +
>  #if defined(__linux__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
>  static void cdrom_parse_filename(const char *filename, QDict *options,
>                                   Error **errp)
> @@ -4012,6 +4333,9 @@ static void bdrv_file_init(void)
>      bdrv_register(&bdrv_file);
>  #if defined(HAVE_HOST_BLOCK_DEVICE)
>      bdrv_register(&bdrv_host_device);
> +#if defined(CONFIG_BLKZONED)
> +    bdrv_register(&bdrv_zoned_host_device);
> +#endif
>  #ifdef __linux__
>      bdrv_register(&bdrv_host_cdrom);
>  #endif

[...]

> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 2173e7734a..c6bbb7a037 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -2942,6 +2942,7 @@
>  # @compress: Since 5.0
>  # @copy-before-write: Since 6.2
>  # @snapshot-access: Since 7.0
> +# @zoned_host_device: Since 7.2
>  #
>  # Since: 2.9
>  ##
> @@ -2955,7 +2956,8 @@
>              'luks', 'nbd', 'nfs', 'null-aio', 'null-co', 'nvme', 'parallels',
>              'preallocate', 'qcow', 'qcow2', 'qed', 'quorum', 'raw', 'rbd',
>              { 'name': 'replication', 'if': 'CONFIG_REPLICATION' },
> -            'ssh', 'throttle', 'vdi', 'vhdx', 'vmdk', 'vpc', 'vvfat' ] }
> +            'ssh', 'throttle', 'vdi', 'vhdx', 'vmdk', 'vpc', 'vvfat',
> +            { 'name': 'zoned_host_device', 'if': 'CONFIG_BLKZONED' } ] }

QAPI naming conventions ask for 'zoned-host-device'.  We may choose to
ignore them to stay closer to existing 'host_device'.

>  
>  ##
>  # @BlockdevOptionsFile:
> @@ -4329,7 +4331,9 @@
>        'vhdx':       'BlockdevOptionsGenericFormat',
>        'vmdk':       'BlockdevOptionsGenericCOWFormat',
>        'vpc':        'BlockdevOptionsGenericFormat',
> -      'vvfat':      'BlockdevOptionsVVFAT'
> +      'vvfat':      'BlockdevOptionsVVFAT',
> +      'zoned_host_device': { 'type': 'BlockdevOptionsFile',
> +                             'if': 'CONFIG_BLKZONED' }
>    } }
>  
>  ##

[...]