Re: [Qemu-devel] [PATCH] block: fix the use of protocols in backing files

[Anthony Liguori]

On 11/04/2010 07:54 AM, Kevin Wolf wrote:
> Am 27.10.2010 20:19, schrieb Anthony Liguori:
>    
> > Signed-off-by: Anthony Liguori<address@hidden>
> >
> > 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) {
> >      
> If no protocol is specified, bdrv_find_protocol doesn't return NULL but
> the file: driver.
>    

An ugly way to handle this would be to do if (strstr(bs->backing_file, 
":") == NULL) instead.

A deeper refactoring could return NULL in bdrv_find_protocol and fixup 
the callers to default to file: if none are specified.

What do you think?

Regards,

Anthony Liguori



> This breaks all backing file related qemu-iotests cases because qcow2
> backing files are opened as raw files now.
>
> Kevin
>