Re: [Qemu-devel] [RFC PATCH 3/4] qmp: Add "snapshot=" option to nbd-server-add

[Eric Blake <eblake@redhat.com>]

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On 07/28/2013 10:25 PM, Fam Zheng wrote:
> With drive-backup block job, we can have a point-in-time snapshot of a
> device. With snapshot=on, a backup block job is started on the device to
> do CoW to a temporary image and this image is exported to nbd. The image
> is deleted after nbd server stops.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  blockdev-nbd.c   | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  hmp.c            |  5 ++--
>  qapi-schema.json |  3 ++-
>  qmp-commands.hx  |  2 +-
>  4 files changed, 80 insertions(+), 6 deletions(-)

In addition to Stefan's comments about missing docs...

> +++ b/qapi-schema.json
> @@ -3225,7 +3225,8 @@
>  #
>  # Since: 1.3.0
>  ##
> -{ 'command': 'nbd-server-add', 'data': {'device': 'str', '*writable': 'bool'} }
> +{ 'command': 'nbd-server-add', 'data': {'device': 'str', '*writable': 'bool',
> +                                        '*snapshot': 'bool'} }

When documenting the new option, be sure to use a (since 1.7) tag.
Also, it would be nice to get introspection in (otherwise, libvirt
cannot learn whether '*snapshot' is supported without trying and failing
on older qemu).

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


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