[systemd-devel] Possible bug when a dummy service declares After= and/or Conflicts= a .mount unit?

[Andrei Borzenkov]

On Wed, Mar 4, 2015 at 11:21 AM, Didier Roche <didrocks at ubuntu.com> wrote:
> Hey,
>
> It seems that we discovered an issue if a service declares some relationship
> with a .mount unit.
> For instance, having tmp.mount disable (and nothing mounting /tmp as tmpfs
> in fstab):
>
> foo.service:
> [Unit]
> After=tmp.mount
>
> [Service]
> ExecStart=/bin/echo foo
>
> [Install]
> WantedBy=multi-user.target
>
>
> Then, enable foo.service
> Many reboots will have /tmp not mounted, but after some reboots (mostly <
> 5), we can get:
>
> tmpfs on /tmp type tmpfs (rw)
> status on tmp.mount:
>    Loaded: loaded (/lib/systemd/system/tmp.mount; disabled; vendor preset:
> enabled)

It says "enabled" here, although I'm not sure what "vendor preset" means.

>    Active: active (mounted) since Wed 2015-03-04 08:54:37 CET; 18min ago
>
> rebooting systemd with debug logs, only one mention of foo.service, but we
> clearly see that tmp.mount is executed, even disabled:
> Mar 04 08:54:37 autopkgtest systemd[1]: Deleting job tmp.mount/stop as
> dependency of job systemd-timesyncd.service/stop
> Mar 04 08:54:37 autopkgtest systemd[1]: Deleting job foo.service/start as
> dependency of job tmp.mount/stop
>
> Mar 04 08:54:37 autopkgtest systemd[1]: Installed new job tmp.mount/start as
> 50
> Mar 04 08:54:37 autopkgtest systemd[1]: ConditionPathIsSymbolicLink=!/tmp
> succeeded for tmp.mount.
> Mar 04 08:54:37 autopkgtest systemd[1]: About to execute: /bin/mount tmpfs
> /tmp -n -t tmpfs -o mode=1777,strictatime
> Mar 04 08:54:37 autopkgtest systemd[1]: Forked /bin/mount as 171
> Mar 04 08:54:37 autopkgtest systemd[1]: tmp.mount changed dead -> mounting
> Mar 04 08:54:37 autopkgtest systemd[1]: Mounting Temporary Directory...
>
> Mar 04 08:54:37 autopkgtest systemd[1]: tmp.mount changed mounting ->
> mounting-done
> Mar 04 08:54:37 autopkgtest systemd[1]: Job tmp.mount/start finished,
> result=done
> Mar 04 08:54:37 autopkgtest systemd[1]: Mounted Temporary Directory.
>
>
> It seems then that any relationship (at least After/Conflicts) to a mount
> unit from a enabled service will trigger that mount unit to executes.
>
> Did anyone else have seen something similar?
> Cheers,
> Didier
>
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