Blue Swirl <blauwir...@gmail.com> writes: > Command line flag '-snapshot' was setting the drive flag 'snapshot' > for all drives. Therefore also CDROM devices were incorrectly marked > with BDRV_O_SNAPSHOT. Thus the backing images were accidentally deleted > at bdrv_open time, for example when changing the image with monitor > 'change' command. > > Fix by adding a separate 'global_snapshot' drive flag for use when the > command line flag '-snapshot' is used. Also add some extra checks > and suppress a kraxelian notation.
This patch doesn't feel right to me. The bug you observed is that snapshot=on does something stupid for a certain kind of drive: bdrv_open_common() removes a "temporary" file that isn't temporary. That bug needs fixing. Your patch does not fix it. Instead, it attempts to avoid the bug: snapshot=on now fails with media=cdrom, and the new -drive option global_snapshot=on gets silently ignored with media=cdrom. Why is media=cdrom the only case where the bug can bite? Why not fix bdrv_open_common()? [...]
