Re: [PATCH v3 2/4] qcow2: add configurations for zoned format extension

[Markus Armbruster]

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 profile" is gone in v3.

> zone model, zone size, zone capacity, number of conventional
> zones, limits on zone resources (max append sectors, max open
> zones, and max_active_zones).
>
> 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 nr_conv_zones=0 -o
> max_append_sectors=512 -o max_open_zones=0 -o max_active_zones=0
> -o zone_model=1
>
> Signed-off-by: Sam Li <faithilikerun@gmail.com>

[...]

> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 2b1d493d6e..0d8f9e0a88 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -5021,6 +5021,27 @@
>  # @compression-type: The image cluster compression method
>  #     (default: zlib, since 5.1)
>  #
> +# @zone-model: Zoned device model, 1 for host-managed and 0 for

Why is this encoded as a number?

If it's fundamentally a flag, use bool.

If more models could appear in the future, make it an enum.

> +#     non-zoned devices (default: 0, since 8.0)

Since 8.2.  More of the same below.

> +#
> +# @zone-size: Total number of logical blocks within zones in bytes
> +#     (since 8.0)
> +#
> +# @zone-capacity: The number of usable logical blocks within zones
> +#     in bytes. A zone capacity is always smaller or equal to the
> +#     zone size. (since 8.0)

Two spaces between sentences for consistency, please.

> +#
> +# @nr-conv-zones: The number of conventional zones of the zoned device
> +#     (since 8.0)

I think @conventional-zones would be more obvious.

> +#
> +# @max-open-zones: The maximal allowed open zones (since 8.0)

Maybe "The maximum number of open zones".

> +#
> +# @max-active-zones: The limit of the zones that have the implicit
> +#     open, explicit open or closed state (since 8.0)

Maybe "The maximum number of zones in the implicit open, explicit open
or closed state".

> +#
> +# @max-append-sectors: The maximal data size in sectors of a zone
> +#     append request that can be issued to the device. (since 8.0)

What's the sector size, and how can the user determine it?  Why can't we
use bytes here?

> +#
>  # Since: 2.12
>  ##
>  { 'struct': 'BlockdevCreateOptionsQcow2',
> @@ -5037,7 +5058,14 @@
>              '*preallocation':   'PreallocMode',
>              '*lazy-refcounts':  'bool',
>              '*refcount-bits':   'int',
> -            '*compression-type':'Qcow2CompressionType' } }
> +            '*compression-type':'Qcow2CompressionType',
> +            '*zone-model':         'uint8',
> +            '*zone-size':          'size',
> +            '*zone-capacity':      'size',
> +            '*nr-conv-zones':      'uint32',
> +            '*max-open-zones':     'uint32',
> +            '*max-active-zones':   'uint32',
> +            '*max-append-sectors': 'uint32' } }
>  
>  ##
>  # @BlockdevCreateOptionsQed: