Re: [Qemu-devel] [PATCH] Warn if a qcow (not qcow2) file is opened

[Paul Brook <paul@codesourcery.com>]

> >>> The qcow block driver format is no longer maintained and likely
> >>> contains
> >>> serious data corruptors.  Urge users to stay away for it, and advertise
> >>> the new and improved replacement.
> >
> > I'm not sure how I feel about this.  Can we prove qcow is broken?  Is
> > it only broken for writes and not reads?
>
> Well, Kevin posted a patch, so it is.  It's definitely unmaintained.
> Given it's a qemu native format, there is no interoperability value
> except with old qemu versions.
>
> > If we're printing a warning, does that mean we want to deprecate qcow
> > and eventually remove it (or remove write support, at least)?
>
> Yes.

IMHO there's little value in just printing a warning. Until it actually goes 
away, people are liable to assume we're just being paranoid/awkward and keep 
using it anyway.

I suggest crippling it now and, assuming noone steps up to fix+maintain it, 
ripping out the write support altogether at next release.
I'm assuming the readonly code is in better shape, and can be supported with 
relatively little effort.

Paul