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Re: [Qemu-devel] [PATCH V5 7/7] qmp: Allow to take external snapshots on
From: |
Benoît Canet |
Subject: |
Re: [Qemu-devel] [PATCH V5 7/7] qmp: Allow to take external snapshots on bs graphs node. |
Date: |
Wed, 22 Jan 2014 22:33:59 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Le Tuesday 21 Jan 2014 à 15:28:49 (+0100), Kevin Wolf a écrit :
> Am 12.12.2013 um 16:34 hat Benoît Canet geschrieben:
> > Signed-off-by: Benoit Canet <address@hidden>
> > ---
> > blockdev.c | 55
> > ++++++++++++++++++++++++++++++++++++++++++++++++-------
> > hmp.c | 4 +++-
> > qapi-schema.json | 13 ++++++++++---
> > qmp-commands.hx | 11 ++++++++++-
> > 4 files changed, 71 insertions(+), 12 deletions(-)
>
> > diff --git a/qapi-schema.json b/qapi-schema.json
> > index 3977619..d7afb69 100644
> > --- a/qapi-schema.json
> > +++ b/qapi-schema.json
> > @@ -1759,18 +1759,25 @@
> > ##
> > # @BlockdevSnapshot
> > #
> > -# @device: the name of the device to generate the snapshot from.
> > +# Either @device or @node-name must be set but not both.
> > +#
> > +# @device: #optional the name of the device to generate the snapshot from.
> > +#
> > +# @node-name: #optional graph node name to generate the snapshot from
> > (Since 2.0)
> > #
> > # @snapshot-file: the target of the new image. A new file will be created.
> > #
> > +# @snapshot-node-name: #optional the graph node name of the new image
> > (Since 2.0)
> > +#
>
> I think we should document how this plays together with snapshot-file,
> format and mode.
What kind of interactions do you expect ?
The only kind of interaction I see is that setting node-name imply that the
user really want to manipulate the graph and that snapshot-node-name is
mandatory as a consequence.
>
> Perhaps this is actually different enough that it would justify creating
> a new QMP command 'blockdev-snapshot' that never creates image files but
> only ever takes existing nodes. The implementation of 'blockdev-snapshot-
> sync' could then become a wrapper around it.
What would be the benefits ?
Best regards
Benoît
>
> > # @format: #optional the format of the snapshot image, default is 'qcow2'.
> > #
> > # @mode: #optional whether and how QEMU should create a new image, default
> > is
> > # 'absolute-paths'.
> > ##
> > { 'type': 'BlockdevSnapshot',
> > - 'data': { 'device': 'str', 'snapshot-file': 'str', '*format': 'str',
> > - '*mode': 'NewImageMode' } }
> > + 'data': { '*device': 'str', '*node-name': 'str',
> > + 'snapshot-file': 'str', '*snapshot-node-name': 'str',
> > + '*format': 'str', '*mode': 'NewImageMode' } }
> >
> > ##
> > # @BlockdevSnapshotInternal
>
> Kevin