Date: Tue, 12 Oct 2004 10:48:29 +0200
From: Matthias Schniedermeyer <ms@citd.de>
To: jonathan@jonmasters.org
Cc: Olaf Fr??czyk <olaf@cbk.poznan.pl>, linux-kernel@vger.kernel.org
Subject: Re: How to umount a busy filesystem?
Message-ID: <20041012084829.GB19493@citd.de>
References: <1097441558.2235.9.camel@venus> <20041010211208.GA6986@citd.de> <1097445655.2235.18.camel@venus> <35fb2e59041011172478b0c09@mail.gmail.com>
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On 12.10.2004 01:24, Jon Masters wrote:
> On Mon, 11 Oct 2004 00:00:55 +0200, Olaf Fr??czyk <olaf@cbk.poznan.pl> wrote:
> > On Sun, 2004-10-10 at 23:12, Matthias Schniedermeyer wrote:
> > > On 10.10.2004 22:52, Olaf Fr?czyk wrote:
> > > > Hi,
> > > >
> > > > Why I cannot umount filesystem if it is being accessed?
> > > > I tried MNT_FORCE option but it doesn't work.
> > > >
> > > > Killing all processes that access a filesystem is not an option. They
> > > > should just get an error when accessing filesystem that is umounted.
> > > >
> > > > Any idea how to do it?
> > >
> > > umount -l
> > >
> > > removes the mount in "lazy"-mode, this way the mount-point "vanishes"
> 
> > Thank you.
> > But this:
> > 1. Does not let the user to remove the media (eg. cdrom).
> > 2. Does not flush buffers etc. so the media cannot be safely removed
> 
> What you want is the kind of proxy Luke Leighton was talking about in
> a recent post to lkml concerning his effort to port FUSE example code
> in to kernelspace. In his model you can replace the underlying
> filesystem because the user processes are only seeing what you present
> through the proxy - so although proxy inodes/superblock/etc. remain
> constant, the underlying filesystem might get swapped around or moved
> someplace else and the proxy has to work out whether to return errors
> or simply block until the backing filesystem is available for use
> again once more.

Hmmm. "Supermount-ng" seems to also be for this type of problem.
(Never tried it myself)

http://supermount-ng.sourceforge.net/


Bis denn

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