Am 19.02.2021 um 16:33 hat Max Reitz geschrieben: > The block job holds a reference to the backup-top node (because it is > passed as the main job BDS to block_job_create()). Therefore, > bdrv_backup_top_drop() cannot delete the backup-top node (replacing it > by its child does not affect the job parent, because that has > .stay_at_node set). That is a problem, because all of its I/O functions > assume the BlockCopyState (s->bcs) to be valid and that it has a > filtered child; but after bdrv_backup_top_drop(), neither of those > things are true.
This kind of suggests that block_copy_state_free() doesn't really belong in bdrv_backup_top_drop(), but in a .bdrv_close callback. Doesn't make this patch less correct, of course. We still want to have all references dropped at the end of bdrv_backup_top_drop(). > It does not make sense to add new parents to backup-top after > backup_clean(), so we should detach it from the job before > bdrv_backup_top_drop(). Because there is no function to do that for a > single node, just detach all of the job's nodes -- the job does not do > anything past backup_clean() anyway. > > Signed-off-by: Max Reitz <[email protected]> Reviewed-by: Kevin Wolf <[email protected]>
