Re: [PATCH v7 2/4] qcow2: add configurations for zoned format extension

[Markus Armbruster]

Sam Li <faithilikerun@gmail.com> writes:

> Markus Armbruster <armbru@redhat.com> 于2024年2月19日周一 13:05写道：
>>
>> One more thing...
>>
>> Markus Armbruster <armbru@redhat.com> writes:
>>
>> > I apologize for the delayed review.
>
> No problems. Thanks for reviewing!
>
>> >
>> > 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>
>> >
>> > [...]
>> >
>> >> diff --git a/qapi/block-core.json b/qapi/block-core.json
>> >> index ca390c5700..e2e0ec21a5 100644
>> >> --- a/qapi/block-core.json
>> >> +++ b/qapi/block-core.json
>> >> @@ -5038,6 +5038,67 @@
>> >>  { '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 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.
>> >
>> > Default?
>
> It should be set by users. No default value provided. If it's unset
> then it is zero and an error will be returned.

If the user must provide @size, why is it optional then?

>> >
>> >> +#
>> >> +# @capacity: The number of usable logical blocks within zones
>> >> +#     in bytes.  A zone capacity is always smaller or equal to the
>> >> +#     zone size.
>> >
>> > Default?
>
> Same.
>
>> >
>> >> +# @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?
>
> Same.
>
> For those values, I guess it could be set when users provide no
> information and still want a workable emulated zoned block device.
>
>> >
>> >> +#
>> >> +# Since 8.2
>> >> +##
>> >> +{ 'struct': 'Qcow2ZoneHostManaged',
>> >> +  'data': { '*size':          'size',
>> >> +            '*capacity':      'size',
>> >> +            '*conventional-zones': 'uint32',
>> >> +            '*max-open-zones':     'uint32',
>> >> +            '*max-active-zones':   'uint32',
>> >> +            '*max-append-bytes':   'size' } }

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