On 11/29/2016 07:18 PM, Max Reitz wrote: > If the backing file is overridden, this most probably does change the > guest-visible data of a BDS. Therefore, we will need to consider this in > bdrv_refresh_filename(). > > Adding a new field to the BDS is not nice, but it is very simple and > exactly keeps track of whether the backing file has been overridden. > > This commit adds a FIXME which will be remedied by a follow-up commit. > Until then, the respective piece of code will not result in any behavior > that is worse than what we currently have. > > Signed-off-by: Max Reitz <mre...@redhat.com> > ---
> +++ b/include/block/block_int.h
> @@ -461,6 +461,7 @@ struct BlockDriverState {
> char backing_file[PATH_MAX]; /* if non zero, the image is a diff of
> this file image */
> char backing_format[16]; /* if non-zero and backing_file exists */
> + bool backing_overridden; /* backing file has been specified by the user
> */
Should we group all of the bool in this struct so as to reduce its size
and improve cache locality? But it's already clunky, so that may be
appropriate as a separate patch.
Reviewed-by: Eric Blake <ebl...@redhat.com>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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