Re: [PATCH v2 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 following arguments: the device size, zoned profile,
> zoned model, zone size, zone capacity, number of conventional
> zones, limits on zone resources (max append sectors, max open
> zones, and max_active_zones). The zoned profile option is set
> to zns when using the qcow2 file as a ZNS drive.
>
> To create a qcow2 file with zoned format, use command like this:
> $ qemu-img create -f qcow2 test.qcow2 -o size=768M -o
> zone_size=64M -o zone_capacity=64M -o zone_nr_conv=0 -o
> max_append_sectors=512 -o max_open_zones=0 -o max_active_zones=0
>  -o zoned_profile=zbc/zns
>
> Signed-off-by: Sam Li <faithilikerun@gmail.com>

[...]

> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 2b1d493d6e..0c97ae678b 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -5020,24 +5020,42 @@
>  #
>  # @compression-type: The image cluster compression method
>  #     (default: zlib, since 5.1)
> +# @zoned-profile: Two zoned device protocol options, zbc or zns
> +#                 (default: off, since 8.0)

When a 'str' thing accepts a fixed set of (string) values, it most
likely should be an enum instead.  Have you considered making
@zoned-profile one?

> +# @zone-size: The size of a zone of the zoned device (since 8.0)
> +# @zone-capacity: The capacity of a zone of the zoned device (since 8.0)

In bytes, I presume?

What's the difference between size and capacity?

> +# @zone-nr-conv: The number of conventional zones of the zoned device
> +#                (since 8.0)
> +# @max-open-zones: The maximal allowed open zones (since 8.0)
> +# @max-active-zones: The limit of the zones that have the implicit open,
> +#                    explicit open or closed state (since 8.0)

Naming...  if I understand the comment correctly, then @zone-nr-conv,
@max-open-zones, and @max-active-zones are all counting zones.  Rename
@zone-nr-conv to @conventional-zones?

> +# @max-append-sectors: The maximal sectors that is allowed to append write

I'm not sure I understand the explanation.  Elaborate for me?

> +#                      (since 8.0)

Please format like

   #
   # @zoned-profile: Two zoned device protocol options, zbc or zns
   #     (default: off, since 8.0)
   #
   # @zone-size: The size of a zone of the zoned device (since 8.0)
   #
   # @zone-capacity: The capacity of a zone of the zoned device
   #     (since 8.0)
   #
   # @zone-nr-conv: The number of conventional zones of the zoned device
   #     (since 8.0)
   #
   # @max-open-zones: The maximal allowed open zones (since 8.0)
   #
   # @max-active-zones: The limit of the zones that have the implicit
   #     open, explicit open or closed state (since 8.0)
   #
   # @max-append-sectors: The maximal sectors that is allowed to append
   #     write (since 8.0)

to blend in with recent commit a937b6aa739 (qapi: Reformat doc comments
to conform to current conventions).

>  #
>  # Since: 2.12
>  ##
>  { 'struct': 'BlockdevCreateOptionsQcow2',
> -  'data': { 'file':             'BlockdevRef',
> -            '*data-file':       'BlockdevRef',
> -            '*data-file-raw':   'bool',
> -            '*extended-l2':     'bool',
> -            'size':             'size',
> -            '*version':         'BlockdevQcow2Version',
> -            '*backing-file':    'str',
> -            '*backing-fmt':     'BlockdevDriver',
> -            '*encrypt':         'QCryptoBlockCreateOptions',
> -            '*cluster-size':    'size',
> -            '*preallocation':   'PreallocMode',
> -            '*lazy-refcounts':  'bool',
> -            '*refcount-bits':   'int',
> -            '*compression-type':'Qcow2CompressionType' } }
> +  'data': { 'file':                'BlockdevRef',
> +            '*data-file':          'BlockdevRef',
> +            '*data-file-raw':      'bool',
> +            '*extended-l2':        'bool',
> +            'size':                'size',
> +            '*version':            'BlockdevQcow2Version',
> +            '*backing-file':       'str',
> +            '*backing-fmt':        'BlockdevDriver',
> +            '*encrypt':            'QCryptoBlockCreateOptions',
> +            '*cluster-size':       'size',
> +            '*preallocation':      'PreallocMode',
> +            '*lazy-refcounts':     'bool',
> +            '*refcount-bits':      'int',
> +            '*compression-type':   'Qcow2CompressionType',

I'd keep the existing lines unchanged.  Not a demand.

> +            '*zoned-profile':      'str',
> +            '*zone-size':          'size',
> +            '*zone-capacity':      'size',
> +            '*zone-nr-conv':       'uint32',
> +            '*max-open-zones':     'uint32',
> +            '*max-active-zones':   'uint32',
> +            '*max-append-sectors': 'uint32'}}

Keep the spaces around the } for consistency.  Yes, they're kind of
ugly.

>  
>  ##
>  # @BlockdevCreateOptionsQed: