Re: [Qemu-devel] [PATCH] QMP: add snapshot_blkdev_sync command

[Anthony Liguori]

On 03/09/2011 10:01 AM, Kevin Wolf wrote:
> Am 09.03.2011 16:46, schrieb Anthony Liguori:
> > On 03/09/2011 09:37 AM, address@hidden wrote:
> > > From: Jes Sorensen<address@hidden>
> > >
> > > Add QMP bits for snapshot_blkdev_sync command. This is the same as
> > > snapshot_blkdev in the human monitor, but added _sync to the name to
> > > make it explicit that the command is synchronous and leave space for a
> > > future async version.
> > >
> > > Signed-off-by: Jes Sorensen<address@hidden>
> > > ---
> > >    qmp-commands.hx |   19 +++++++++++++++++++
> > >    1 files changed, 19 insertions(+), 0 deletions(-)
> > >
> > > diff --git a/qmp-commands.hx b/qmp-commands.hx
> > > index 9d3cc31..e32187e 100644
> > > --- a/qmp-commands.hx
> > > +++ b/qmp-commands.hx
> > > @@ -667,6 +667,25 @@ Example:
> > >    EQMP
> > >
> > >        {
> > > +        .name       = "snapshot_blkdev_sync",
> > > +        .args_type  = "device:B,snapshot_file:s?,format:s?",
> > > +        .params     = "device [new-image-file] [format]",
> > > +        .help       = "initiates a live snapshot\n\t\t\t"
> > > +                      "of device. If a new image file is specified, 
> > > the\n\t\t\t"
> > > +                      "new image file will become the new root image.\n\t\t\t"
> > > +                      "If format is specified, the snapshot file will\n\t\t\t"
> > > +                      "be created in that format. Otherwise the\n\t\t\t"
> > > +                      "snapshot will be internal! (currently unsupported)",
> > > +        .user_print = monitor_user_noop,
> > > +        .mhandler.cmd_new = do_snapshot_blkdev,
> > > +    },
> > > +
> > > +SQMP
> > > +Synchronous snapshot of block device, using snapshot file as target
> > > +if provided.
> > Please document the error semantics.
> >
> > The documentation in .help is discarded for QMP.  You should put the
> > docs in the SQMP section.
> >
> > Also, QMP should use '-' instead of '_'.  We should also try to follow
> > the form 'noun'-'verb' so the name would be better as 'blkdev-snapshot-sync'
> >
> > I'm not sure blkdev is the right prefix.  Kevin, what are your thoughts
> > here?  Does 'blkdev' make sense for any command operating on a block
> > device (that is, a qdev device that happens to have a block drive, not
> > the same thing as -blockdev that we've discussed in the past).
> Doesn't this command work on a -blockdev style thing, i.e.
> BlockDriverState or DriveInfo? I don't think we have any commands that
> refer to qdev devices that happen to be block devices. You could
> probably argue that some of them should...

'device' is a device name though, right?  Or is it a name associated 
with a BlockDriverState that currently happens to be a qdev name?

Would I be able to eventually pass a qdev path here?

If the answer is that this is a bdrv_name, then should we at least use 
blockdev instead of blkdev?

Regards,

Anthony Liguori



> Kevin