Re: [PATCH v10 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:
> 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=6 \
> -o zone.max_active_zones=8 -o zone.mode=host-managed
>
> Signed-off-by: Sam Li <faithilikerun@gmail.com>

[...]

Just doc polish this time around.  Never been closer!

> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 508b081ac1..d771dfb4a1 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -5268,6 +5268,70 @@
>  { 'enum': 'Qcow2CompressionType',
>    'data': [ 'zlib', { 'name': 'zstd', 'if': 'CONFIG_ZSTD' } ] }
>  
> +##
> +# @Qcow2ZoneModel:
> +#
> +# Zoned device model used in qcow2 image file
> +#
> +# @host-managed: The host-managed model only allows sequential write
> +#     over the device zones.
> +#
> +# Since 11.0

It's 11.1 now.  More of the same below, not flagging it again.

> +##
> +{ 'enum': 'Qcow2ZoneModel',
> +  'data': [ 'host-managed'] }
> +
> +##
> +# @Qcow2ZoneHostManaged:
> +#
> +# The host-managed zone model.  It only allows sequential writes.
> +#
> +# @size: Total number of bytes within zones (default 256 MB).
> +#
> +# @capacity: The number of usable logical blocks within zones
> +#     in bytes.  A zone capacity is always smaller or equal to the
> +#     zone size (default to zone size).

"Number blocks ... in bytes" is awkward.  Do you mean the usable space,
which is a multiple of the logical block size?

> +#
> +# @conventional-zones: The number of conventional zones of the
> +#     zoned device (default 0).
> +#
> +# @max-open-zones: The maximal number of open zones.  It is less than
> +#     or equal to the number of sequential write required zones of
> +#     the device (default 0).

Is the "number of sequential write required zones" visible via QMP?

> +#
> +# @max-active-zones: The maximal number of zones in the implicit
> +#     open, explicit open or closed state.  It is less than or equal
> +#     to the max open zones (default 0).

"to the maximal number of open zones" or "to @max-open-zones"

> +#
> +# @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 and less than the zone capacity
> +#     (default 64 KB).

"Must be 512-byte aligned": do you mean it must be a multiple of 512?

> +#
> +# Since 11.0
> +##
> +{ 'struct': 'Qcow2ZoneHostManaged',
> +  'data': { '*size':          'size',
> +            '*capacity':      'size',
> +            '*conventional-zones': 'uint32',
> +            '*max-open-zones':     'uint32',
> +            '*max-active-zones':   'uint32',
> +            '*max-append-bytes':   'size' } }
> +
> +##
> +# @Qcow2ZoneCreateOptions:
> +#
> +# The zone device model for the qcow2 image.

"Device model" has a specific meaning in QEMU: it's a device frontend,
such as "ide-hd", "e1000", "usb-tablet", ...

Maybe something like "Creation options for zoned qcow2 images"?

> +#
> +# @mode: The zone device model modes.

Sure its plural modes, and not mode?

> +#
> +# Since 11.0
> +##
> +{ 'union': 'Qcow2ZoneCreateOptions',
> +  'base': { 'mode': 'Qcow2ZoneModel' },
> +  'discriminator': 'mode',
> +  'data': { 'host-managed': 'Qcow2ZoneHostManaged' } }
> +
>  ##
>  # @BlockdevCreateOptionsQcow2:
>  #
> @@ -5310,6 +5374,9 @@
>  # @compression-type: The image cluster compression method
>  #     (default: zlib, since 5.1)
>  #
> +# @zone: The zone device model modes.  The default is that the
> +#     device is not zoned.  (since 11.0)

Maybe something like

   # @zone: Options for zoned images.  If absent, the device is not
   #     zoned.  (Since 11.0)

> +#
>  # Since: 2.12
>  ##
>  { 'struct': 'BlockdevCreateOptionsQcow2',
> @@ -5326,7 +5393,8 @@
>              '*preallocation':   'PreallocMode',
>              '*lazy-refcounts':  'bool',
>              '*refcount-bits':   'int',
> -            '*compression-type':'Qcow2CompressionType' } }
> +            '*compression-type':'Qcow2CompressionType',
> +            '*zone':            'Qcow2ZoneCreateOptions' } }
>  
>  ##
>  # @BlockdevCreateOptionsQed: