rollback of snapshot:LUN deactivate failure - in-use

I have a question about the rollback of snapshot.
Here is the current situation, a failed message called 'LUN deactivate failure - in-use ' returned when I try to send a rollback request to the iscsi-gw .and a successful message returned only if I logout all the hosts under the current iscsi-target.
Since there is no need to logout all the hosts under the current iscsi-target, we should be able to rollback the snapshot when we have logout the host to which the image that needs rollback belongs.
Here is my solution . your opinions are greatly welcomed.

[rbd-target-api.py.txt](https://github.com/ceph/ceph-iscsi-cli/files/2801845/rbd-target-api.py.txt)