Comment 75 for bug 1569925

## SUMMARY 1

Affects open-iscsi (NOT systemd):

* ISCSID NEEDS TO BE UP & RUNNING (AND LOGGED TO PORTAL) FOR THE LOGOUT TO WORK

https://pastebin.canonical.com/197359/

Daemon shutdown documentation in iscsiadm command says (about stopping iscsid daemon with iscsiadm -k):
""" ... This will immediately stop all iscsid operations and shutdown iscsid. It does not logout any sessions. Running this command is the same as doing "killall iscsid". Neither should normally be used, because if iscsid is doing error recovery or if there is an error while iscsid is not running, the system may not be able to recover. This command and iscsid's SIGTERM handling are experimental. """

Basically meaning you're not able to shutdown the daemon in a clean manner if you have connected sessions. And basically, checking the pastebin, you see the need for running iscsid daemon to logout through iscsiadm command.

So from:

(systemctl edit --full open-iscsi.service)
...
Wants=network-online.target remote-fs-pre.target iscsid.service
After=network-online.target iscsid.service
Before=remote-fs-pre.target
...
ExecStartPre=/bin/systemctl --quiet is-active iscsid.service
ExecStart=/sbin/iscsiadm -m node --loginall=automatic
ExecStart=/lib/open-iscsi/activate-storage.sh
ExecStop=/lib/open-iscsi/umountiscsi.sh
ExecStop=/bin/sync
ExecStop=/lib/open-iscsi/logout-all.sh
...

and

(systemctl edit --full iscsid.service)
...
Wants=network-online.target remote-fs-pre.target
Before=remote-fs-pre.target
After=network.target network-online.target
...
ExecStartPre=/lib/open-iscsi/startup-checks.sh
ExecStart=/sbin/iscsid
ExecStop=/sbin/iscsiadm -k 0 2
...

If umountiscsi.sh (it doesn't kill applications using a mount point) can't umount a mount point (from fstab generator or a mount unit) that is still being used, the logout-all.sh will fail for logging out the session of the disk being used. But this service unit would be considered stopped, allowing "iscsid.service" unit to also be shutdown (killing the iscsid daemon and leaving an opened iscsi session).

This would be problematic for iscsi root disks AND for the kernel issue (comment #73), and this is being taken care by Francis Ginther (fginther) in the next iscsi SRU: https://pastebin.canonical.com/196463/ by creating an iscsi-cleanup.service that will run a script that logs out all remaining iscsi sessions (including /) right before kernel shutdown is called by systemd-shutdown like showed in comment #73.