Comment 16 for bug 1061639

To detect what is keeping / filesystem busy I put a:

lsof / > /openfiles.txt
sync

on top of /etc/init.d/umountroot

In my case it results that dhclient and dnsmasq are most likely to be the root cause; who is supposed to bring them down?
I disabled dnsmasq commenting dns=dnsmasq in /etc/NetworkManager/NetworkManager.conf and add a "killall dhclient" in if-down.d and now shutdowns are clean on my 3 machines.

On the other hand "service networking stop" still takes ages to complete (but only the first time you do it) which leads to think that there is also something else which is not working properly with dbus.

This issue seems really critical to me as well: shutdown time is worsened (at least 3x in my case) while boot time suffers from time needed for fsck (which is triggered every time since the fs is dirty).
So both user experience is impaired and data integrity is at risk, but is not so clear against wich package to file a bug.
Expecially since it can be some weird interaction between them and I would not take for granted that ifupdown is not relevant anymore.