Re: [Qemu-devel] [PATCH v2 3/6] qemu-img: add support for conv=nocreat, notrunc args to dd command

["Daniel P. Berrange" <berrange@redhat.com>]

On Fri, Feb 03, 2017 at 10:44:46PM +0100, Max Reitz wrote:
> On 03.02.2017 13:02, Daniel P. Berrange wrote:
> > The -n arg to the convert command allows use of a pre-existing image,
> > rather than creating a new image. This adds equivalent functionality
> > to the dd command using the 'conv' arg. If 'conv=nocreat' is used,
> > then it will assume the image already exists. The existing image
> > will be truncated to match the required output size. 'conv=notrunc'
> > cna be used to preserve the existing image size.
> > 
> > Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> > ---
> >  qemu-img-cmds.hx |   4 +-
> >  qemu-img.c       | 137 +++++++++++++++++++++++++++++++++++++++++--------------
> >  qemu-img.texi    |  10 +++-
> >  3 files changed, 115 insertions(+), 36 deletions(-)
> 
> Quite frankly I don't like this patch very much. It's not bad in itself,
> but I don't like the idea of giving qemu-img dd new features until it's
> an interface for qemu-img convert. Everything that we add now encourages
> new users to use it and will make the conversion a bit more difficult.
> 
> As long as qemu-img convert gets a --target-image-opts, I don't think we
> need all of this functionality in qemu-img dd.
> 
> Anyway, I won't block/NACK this patch, so resuming review.

I'm going to drop this patch and focus on just fixing qemu-img convert
for now. We can re-visit 'dd' at a later date, once it is clear what
will happen to it wrt refactoring to run above 'convert'.

Regards,
Daniel
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