Re: Debian, FHS & /floppy [offtopic]

["Dave Blau" <dblau@inktomi.com>]

----- Original Message -----
From: "Thomas Sippel - Dau" <t.sippel-dau@ic.ac.uk>
To: "martin f krafft" <madduck@madduck.net>
Cc: "Debian User List" <debian-user@lists.debian.org>;
<freestandards-fhs-discuss@lists.sourceforge.net>
Sent: Tuesday, January 15, 2002 08:46
Subject: Re: Debian, FHS & /floppy


[snip]
> Unmounting the media is much more difficult, and is IMHO a basic flaw
> of Linux (and many other commercial Unix) systems. The unmounting
> solicits a laconic "... busy" message. What should happen is that all
> local processes are signalled if the owner removes a removable media
> mount, and NFS mounts receive a "stale file handle" message the next
> time they try accessing the stuff. This behaviour should at least be
> available as a mount option (-o bump, say), even if the default is
> deemed to be -o nobump (the current bahaviour). Maybe now with a
> development stream available some kind soul will put this into the
> kernel.

I believe this is the intended effect of 'umount -f'. There is a hook for
this
case in the kernel VFS (superblock->s_op->umount_begin()). This function
is called very early in the umount algorithm, and its purpose is to abort
all
transactions on the FS. Unfortunately, this kind of abort is FS-dependant
(think NFS vs ext2 vs msdos), and must be implemented by each FS module.
Currently, only NFS implements it AFAIK. It may be possible to do a (nearly)
generic implementation of umount_begin(), a la the generic_file_read()
function.

-- Dave