On Thu, Oct 28, 2010 at 09:30:09AM +0100, Stefan Hajnoczi wrote:
> On Wed, Oct 27, 2010 at 7:19 PM, Anthony Liguori <aligu...@us.ibm.com> wrote:
> > Signed-off-by: Anthony Liguori <aligu...@us.ibm.com>
> >
> > diff --git a/block.c b/block.c
> > index 1a965b2..00b6f21 100644
> > --- a/block.c
> > +++ b/block.c
> > @@ -603,10 +603,16 @@ int bdrv_open(BlockDriverState *bs, const char
> > *filename, int flags,
> > BlockDriver *back_drv = NULL;
> >
> > bs->backing_hd = bdrv_new("");
> > - path_combine(backing_filename, sizeof(backing_filename),
> > - filename, bs->backing_file);
> > - if (bs->backing_format[0] != '\0')
> > - back_drv = bdrv_find_format(bs->backing_format);
> > + back_drv = bdrv_find_protocol(bs->backing_file);
> > + if (!back_drv) {
> > + path_combine(backing_filename, sizeof(backing_filename),
> > + filename, bs->backing_file);
> > + if (bs->backing_format[0] != '\0')
> > + back_drv = bdrv_find_format(bs->backing_format);
> > + } else {
> > + pstrcpy(backing_filename, sizeof(backing_filename),
> > + bs->backing_file);
> > + }
> >
> > /* backing files always opened read-only */
> > back_flags =
> > --
> > 1.7.0.4
>
> I think this makes sense.
>
> Now it is possible to specify backing files that are relative to
> QEMU's current working directory using file:filename. I don't see
> harm in this.
Shouldn't a backing file be treated as relative to the image file pointing
to it, rather than the QEMU working directory. eg so you can do
# qemu-img create backing.img
# qemu-img create -o backing_file=file:backing.img main.img
And have main.img be able to resolve backing.img in its same directory,
no matter what directory QEMU itself is executing from
Regards,
Daniel
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