Re: [Qemu-devel] [PATCH 2/2] qcow2: mark image as corrupt if failing during create

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

On Fri, Feb 22, 2019 at 08:21:26PM +0100, Max Reitz wrote:
> On 19.02.19 13:50, Daniel P. Berrangé wrote:
> > During creation we write a minimal qcow2 header and then update it with
> > extra features. If the updating fails for some reason we might still be
> > left with a valid qcow2 image that will be mistakenly used for I/O. We
> > cannot delete the image, since we don't know if we created the
> > underlying storage or not. Thus we mark the header as corrupt to
> > prevents its later usage.
> > 
> > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> > ---
> >  block/qcow2.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/block/qcow2.c b/block/qcow2.c
> > index ecc577175f..338513e652 100644
> > --- a/block/qcow2.c
> > +++ b/block/qcow2.c
> > @@ -3104,6 +3104,9 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
> >  
> >      ret = 0;
> >  out:
> > +    if (ret < 0) {
> > +        qcow2_mark_corrupt(blk_bs(blk));

...snip...

> Or maybe Eric's suggestion really is for the best, i.e. mark the image
> corrupt from the start and then clean that after we're all done.  You
> don't need a new flag for that, we already have BDRV_O_CHECK.

Ah, I didn't realize that is what BDRV_O_CHECK could do. I'll try this
approach as it is nicer.


Regards,
Daniel
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