Re: [Qemu-devel] [RFC 1/8] block: add virtual_size to query-block QMP output

[Eric Blake]

On 03/09/2013 03:22 PM, Stefan Hajnoczi wrote:
> There is currently no way to query the size of a drive.  Add a
> 'virtual_size' field to the 'query-block' QMP output.
> 
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> ---
>  block.c          | 1 +
>  qapi-schema.json | 5 ++++-
>  2 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/block.c b/block.c
> index 124a9eb..0128e27 100644
> --- a/block.c
> +++ b/block.c
> @@ -2908,6 +2908,7 @@ BlockInfo *bdrv_query_info(BlockDriverState *bs)
>          info->has_inserted = true;
>          info->inserted = g_malloc0(sizeof(*info->inserted));
>          info->inserted->file = g_strdup(bs->filename);
> +        info->inserted->virtual_size = bdrv_getlength(bs);
>          info->inserted->ro = bs->read_only;
>          info->inserted->drv = g_strdup(bs->drv->format_name);
>          info->inserted->encrypted = bs->encrypted;
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 28b070f..6b64aec 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -751,6 +751,8 @@
>  #
>  # @iops_wr: write I/O operations per second is specified
>  #
> +# @virtual_size: size of block device, in bytes

It is traditional to list 'since 1.5' when adding a field that did not
appear in earlier qemu releases.

> +#
>  # Since: 0.14.0
>  #
>  # Notes: This interface is only found in @BlockInfo.
> @@ -760,7 +762,8 @@
>              '*backing_file': 'str', 'backing_file_depth': 'int',
>              'encrypted': 'bool', 'encryption_key_missing': 'bool',
>              'bps': 'int', 'bps_rd': 'int', 'bps_wr': 'int',
> -            'iops': 'int', 'iops_rd': 'int', 'iops_wr': 'int'} }
> +            'iops': 'int', 'iops_rd': 'int', 'iops_wr': 'int',
> +            'virtual_size': 'int' } }

I was about to suggest 'virtual-size' instead of 'virtual_size', since
we prefer '-' over '_' in QMP; but since this command has pre-existing
uses of '_', keeping consistency within the struct trumps consistency
with the rest of QMP.

The idea makes sense, and my only complaint was a trivial documentation
matter; so feel free to add this when re-posting without the RFC:

Reviewed-by: Eric Blake <address@hidden>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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