Comment 60 for bug 468589

Hi Martin,

If you use umount -f with a bind mount, it is not only the bind mount that goes, but the underlying device gets umounted as well. This of course can have undesired effects.

In the case of wubi 9.04, /boot is bind mounted onto the /host device (which is the one hosting the root loopfile). Unmounting the /boot mountpoint therefore you also unmount /host which is not what we want.

I am not sure if there are any use cases other than wubi. Weak mountpoints are all mountpoints that use any device mounted before and including root. Therefore those mounpoints are unmounted without using force (-f).

The weak-mountpoint behaviour has been the default in a while, it was a regression in karmic that I didn't notice before this report. So the patch restores previous behaviour.

The reason it was not spotted in all the tests, is that wubi 9.10 does not use a bind mounted /boot anymore and therefore the regression did not have any impact.