[BusyBox] Endless "umount" corner cases: judgement call time...

Aurelien Jacobs aurel at gnuage.org
Fri Aug 5 01:29:23 UTC 2005

On Thu, 4 Aug 2005 08:59:00 -0500
Rob Landley <rob at landley.net> wrote:

> Okay, with 2.6 you can now happily mount the same block device in
> several  places and it acts a bit like multiple --bind mounts (they'll
> all share the  same superblock so nothing gets corrupted).
> So, if you mount /dev/hda4 in three places and then umount
> /dev/hda4... Does  this mean all three places should be unmounted?  Or
> just the most recent one?   (Note you can specify a directory you want
> unmounted, and this is now a  different thing than specifying the
> block devices.  Unmounts now always try  to work on directories
> because the current internal logic that tries to deal  with a --bind
> mount and convert that to a block device is going to get really 
> confused.  Not that I'm ever quite sure what it expected to do
> umounting an  NFS mount or ramfs anyway...)
> Anyway, I'm leaning towards "umount /dev/hda4" umounts all instances
> of hda4,  because if you wanted to specify umounting a specific
> directory you've have  indicated the directory.  But I'd like a show
> of hands about this.  (It  wasn't an issue back before bind mounts
> existed because you couldn't mount a  block device in two places and
> expect it to work back then.)

What util-linux mount version do is just unmounting the most recent one.
Now, wether you want to respect what this kind of "standard" version do
is another question.


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