[systemd-devel] shutdown umount order

Ilya Basin basinilya at gmail.com
Sat Mar 16 05:17:37 PDT 2013

CG> 'Twas brillig, and Ilya Basin at 04/01/13 22:22 did gyre and gimble:
>> Hi list.
>> On shutdown I have
>>    Buffer I/O error on device dm-...
>> because the truecrypt disk is unmounted later than the usb disk
>> containing the truecrypt image.
>> I think this happens, because
>> 1) systemd can't figure out the correct mount dependencies
>> 2) umount is called with the force flag
>> ---------
>> There are workarounds specially for truecrypt, but why not solve the
>> problem entirely?
>> 1) I think the mount dependencies can't be made 100% reliable. systemd
>> should use the combination of them and /proc/mounts, but only as a HINT
>> In my case /proc/mounts contains the right order.
>> 2) Instead of force umount, systemd should first try to umount
>> everything gracefully, and if at least one mount point was unmounted
>> successfully, then retry.
>> Only if all mounts are busy, systemd should force umount the first
>> candidate and then repeat the graceful umount for others.

CG> I'm pretty sure the umounting/shutdown logic does exactly this already.
CG> It loops over the devices trying to unmount them and only when no
CG> changes on a complete run of the loop does it exit.

CG> http://cgit.freedesktop.org/systemd/systemd/tree/src/core/umount.c#n555

Thanks. Is there a way debug systemd during shutdown? Maybe on


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