DevStack中rejoin的时候，出现 ERROR cinder.service [-] Manager for service cinder-volume ubuntu@lvmdriver-1 is reporting problems

solution：

sudo losetup /dev/loop0 /opt/stack/data/stack-volumes-default-backing-file

sudo losetup /dev/loop1 /opt/stack/data/stack-volumes-lvmdriver-1-backing-file

If files still exist under /opt/stack just losetup is enough, if they are gone you need reinstall (./stack.sh ) and save them ( for example in $HOME ), because you will need restore them from $HOME location before rejoin_stack.sh