Re: [PATCH v6 2/4] qcow2: add configurations for zoned format extension

[Markus Armbruster <armbru@redhat.com>]

Sam Li <faithilikerun@gmail.com> writes:

> To configure the zoned format feature on the qcow2 driver, it
> requires settings as: the device size, zone model, zone size,
> zone capacity, number of conventional zones, limits on zone
> resources (max append bytes, max open zones, and max_active_zones).
>
> To create a qcow2 image with zoned format feature, use command like
> this:
> $path/to/qemu-img create -f qcow2 zbc.qcow2 -o size=768M

I'd omit $path/to/

> -o zone.size=64M -o zone.capacity=64M -o zone.conventional_zones=0
> -o zone.max_append_bytes=4096 -o zone.max_open_zones=10
> -o zone.max_active_zones=12 -o zone.mode=host-managed

Suggest to add \ like this:

  qemu-img create -f qcow2 zbc.qcow2 -o size=768M \
  -o zone.size=64M -o zone.capacity=64M -o zone.conventional_zones=0 \
  -o zone.max_append_bytes=4096 -o zone.max_open_zones=10 \
  -o zone.max_active_zones=12 -o zone.mode=host-managed

>
> Signed-off-by: Sam Li <faithilikerun@gmail.com>

[...]

> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index ca390c5700..ef98dc83a0 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -5038,6 +5038,64 @@
>  { 'enum': 'Qcow2CompressionType',
>    'data': [ 'zlib', { 'name': 'zstd', 'if': 'CONFIG_ZSTD' } ] }
>  
> +##
> +# @Qcow2ZoneModel:
> +#
> +# Zoned device model used in qcow2 image file
> +#
> +# @host-managed: host-managed model only allows sequential write over the

Suggest "the host-managed model ..."

> +#     device zones
> +#
> +# Since 8.2
> +##
> +{ 'enum': 'Qcow2ZoneModel',
> +  'data': [ 'host-managed'] }
> +
> +##
> +# @Qcow2ZoneHostManaged:
> +#
> +# The host-managed zone model.  It only allows sequential writes.
> +#
> +# @size: Total number of bytes within zones
> +#
> +# @capacity: The number of usable logical blocks within zones
> +#     in bytes.  A zone capacity is always smaller or equal to the
> +#     zone size
> +#
> +# @conventional-zones: The number of conventional zones of the
> +#     zoned device
> +#
> +# @max-open-zones: The maximal number of open zones
> +#
> +# @max-active-zones: The maximal number of zones in the implicit
> +#     open, explicit open or closed state
> +#
> +# @max-append-bytes: The maximal number of bytes of a zone
> +#     append request that can be issued to the device.  It must be
> +#     512-byte aligned

Missing period at the end.

For all the optional members: what's the default?

> +#
> +# Since 8.2
> +##
> +{ 'struct': 'Qcow2ZoneHostManaged',
> +  'data': { '*size':          'size',
> +            '*capacity':      'size',
> +            '*conventional-zones': 'uint32',
> +            '*max-open-zones':     'uint32',
> +            '*max-active-zones':   'uint32',
> +            '*max-append-bytes':   'uint32' } }

Why isn't @max-append-bytes 'size'?  It's a byte count...

> +
> +##
> +# @Qcow2ZoneCreateOptions:
> +#
> +# The zone device model for the qcow2 image.
> +#
> +# Since 8.2
> +##
> +{ 'union': 'Qcow2ZoneCreateOptions',
> +  'base': { 'mode': 'Qcow2ZoneModel' },
> +  'discriminator': 'mode',
> +  'data': { 'host-managed': 'Qcow2ZoneHostManaged' } }
> +
>  ##
>  # @BlockdevCreateOptionsQcow2:
>  #
> @@ -5080,6 +5138,8 @@
>  # @compression-type: The image cluster compression method
>  #     (default: zlib, since 5.1)
>  #
> +# @zone: @Qcow2ZoneCreateOptions.  The zone device model modes (since 8.2)

Don't put the type into the description like that, because it comes out
like

    "zone": "Qcow2ZoneCreateOptions" (optional)
       "Qcow2ZoneCreateOptions".  The zone device model modes (since 8.2)

in formatted documentation.

Let's spell out the default: the device is not zoned.

> +#
>  # Since: 2.12
>  ##
>  { 'struct': 'BlockdevCreateOptionsQcow2',
> @@ -5096,7 +5156,8 @@
>              '*preallocation':   'PreallocMode',
>              '*lazy-refcounts':  'bool',
>              '*refcount-bits':   'int',
> -            '*compression-type':'Qcow2CompressionType' } }
> +            '*compression-type':'Qcow2CompressionType',
> +            '*zone':            'Qcow2ZoneCreateOptions' } }
>  
>  ##
>  # @BlockdevCreateOptionsQed: