[systemd-devel] shutdown umount order

[Ilya Basin]

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.