On Wed, Feb 11, 2015 at 9:39 PM, Stefan Hajnoczi <stefa...@redhat.com> wrote:
> On Tue, Feb 10, 2015 at 11:04:31PM +0800, Xiaodong Gong wrote: > > On Mon, Feb 9, 2015 at 10:54 PM, Stefan Hajnoczi <stefa...@gmail.com> > wrote: > > > > > On Sun, Feb 08, 2015 at 08:39:52PM +0800, Xiaodong Gong wrote: > > > > When open the vpc snapshot based FIXED format, its backing file, > > > > this FIXED vpc image, could be probed as a raw image, because that > > > > the find_image_format just checkout the first sector. > > > > > > > > Add a re-probe for the last sector to FIXED base vpc image,when get > > > > a NULL or raw driver in first sector probe. > > > > > > > > Signed-off-by: Xiaodong Gong <gongxiaodo...@huawei.com> > > > > --- > > > > block.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++------- > > > > 1 file changed, 48 insertions(+), 7 deletions(-) > > > > > > This approach is likely to cause issues because it makes no distiction > > > between headers and footers. Most image formats only have a header and > > > would now be misdetected if a raw image had a header in its last > sector. > > > > > > When a vpc image has a backing file, does it make sense to set the > > > bs->backing_format to "vpc"? That way we'll try to open the backing > > > file as a vpc image without probing. > > > > > > Stefan > > > > > > > > > It works, but this probing of format sounds good . Giving a argument of > bs > > to bdrv_probe and each of funtion of probe get it's own checking method > is > > better, but the foot-print of patch is longer. > > I'm not suggesting a longer patch. > > Can the vpc .bdrv_open() code that loads the backing filename also set > bs->backing_format to "vpc" so QEMU will always use vpc for the backing > file? > > Stefan > It is not a perfect choice, but a right one. I will give a v2 of patch.
