Re: [Qemu-devel] [PATCH 3/7] qcow: Support .bdrv_co_create

[Kevin Wolf]

Am 09.03.2018 um 22:58 hat Eric Blake geschrieben:
> On 03/09/2018 03:46 PM, Kevin Wolf wrote:
> > This adds the .bdrv_co_create driver callback to qcow, which
> > enables image creation over QMP.
> > 
> > Signed-off-by: Kevin Wolf <address@hidden>
> > ---
> >   qapi/block-core.json |  21 +++++-
> >   block/qcow.c         | 196 
> > ++++++++++++++++++++++++++++++++++-----------------
> >   2 files changed, 150 insertions(+), 67 deletions(-)
> 
> Pre-review question: do we REALLY want to support creation of new qcow
> images from QMP?  Or are we at the point where we want to declare qcow
> a read-only format where we only support it to the extent that you can
> convert an existing qcow file into a better supported format like
> qcow2?

I don't think we want read-only formats if it can be avoided, because
we're in a much worse position to run tests then.

The other option you mentioned in your reply to the qed patch, just not
implementing .bdrv_co_create, but keeping the old callback, would mean
that we'd be stuck in a half-converted state forever. My goal is to get
rid of .bdrv_co_create_opts in the long run.

And actually, qcow and qed were two of the simpler conversions where
little remains to be done before the logic in .bdrv_co_create_opts can
be generalised in block.c.

So I'd just do the conversion.

Kevin