[systemd-devel] [PATCH] path_is_mount_point: handle false positive on some fs

[Didier Roche]

Le 10/03/2015 18:54, Lennart Poettering a écrit :
> On Tue, 10.03.15 18:01, Didier Roche (didrocks at ubuntu.com) wrote:
>
>> The context is bug
>> https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1411140, where
>> systemd-machine-id-commit unit is entering in failed state (the binary
>> handles gracefully the fact that it can't unmount the file) on a default
>> ubuntu live system (which is a squashfs/overlayfs system).
> Hmm, it's not clear to me by that bug what precisely fails... Any
> idea? Maybe it would be better to just handle that failure gracefully...

Basically, ConditionPathIsMountPoint=/etc/machine-id is met in the unit 
and so systemd-machine-id-commit is launched.

This one:
- executes the double checking path_is_mount_point(etc_machine_id, 
false) successfully (of course)
- find that machine-id fd is a temporary fs (based on the same issue), 
read the machine-id file content
- switch namespace
- call unmount(etc_machine_id), which obviously fails as there is 
nothing to unmount. I don't think we should shadow that failure and not 
returning in error here, right?

Didier