Am 27.10.2017 um 10:57 hat Jeff Cody geschrieben: > The on disk image format 'inuse' header field is updated blindly if the > image is opened RDWR. This can cause problems if the QEMU runstate is > set to INMIGRATE, at which point the underlying file is set to INACTIVE. > This causes an assert in bdrv_co_pwritev(). > > Do something similar to what is done in VHDX; latch the first write, and > update the header the first time we modify the file. > > Signed-off-by: Jeff Cody <jc...@redhat.com>
For VHDX, it seems that we have to have the header update in the write path anyway, so it might be justifiable, but I think for parallels, it's just ugly. The conservative approach to this would be doing the header write in .bdrv_open() only if BDRV_O_INACTIVE is cleared, and otherwise do it during .bdrv_invalidate_cache(). By the way, random design thought: It might make sense to change .bdrv_open() so that it always opens inactive images and then call .bdrv_invalidate_cache() (possibly renamed to .bdrv_activate()) unconditionally even without migration. Kevin
