[systemd-devel] failing unmounts during reboot

[Silvio Knizek]

Am Donnerstag, den 25.07.2019, 11:40 +0200 schrieb Frank Steiner:
> Hi,
>
> I'm currently discussing a problem with the SuSE support about
> failing
> unmounts during reboot. Tyring to debug this I realized that systemd
> is not killing processes left over by some init.d script. E.g. use
> the following script in /etc/init.d/
>
> #!/bin/sh
> #
> ### BEGIN INIT INFO
> # Provides: bla
> # Required-Start: $network $remote_fs sshd
> # Required-Stop: $network $remote_fs sshd
> # Default-Start:  2 3 5
> # Description:    test
> ### END INIT INFO
> case "$1" in
>       start) cd /test; /usr/bin/sleep 99d & ;;
>        stop) true;;
> esac
>
>
> On shutdown, unmounting /test will fail because the sleep process is
> not killed. Shouldn't there be a mechanism in system to kill
> processes
> spawned by LSB script when shutting these down?
>
> And moreover, wouldn't it make sense to have a mechanism to at least
> try to kill all processes using a filesystem before unmounting it?
> We often see failing unmounts of several local or iscsi fs during
> reboot, and in the support case we are currently working on with SuSE
> failing iscsi fs even cause xfs I/O errors. So it might be a good
> idea
> to have sth. like a lsof + kill before unmounting a filesystem, maybe
> configurable with a flag to enable or disable it. Even if lsof or
> kill
> failed, it wouldn't be worse than now.
>
> As far as I see there is no way to write a drop-in for a mount unit
> that allows to execute commands before the unmount happens, is that
> right? Sth. like "ExecPreUmount=" would help here, especially if
> there
> was sth. like a umount at .service that would be called for every umount
> with e.g. the mounpoint accessable with a variable.
>
> cu,
> Frank
>
Hi,

the proper approach would be to define the dependency of the generated
.service to the mount point with a drop-in and RequiresMountsFor=. See
man:systemd.unit for more information.
Also the systemd-sysv-generator can only do so much. Please write
yourself proper units if you encounter problems.

BR
Silvio