Re: bug with multiple mounts of filesystems in 2.6

[Herbert Poetzl <herbert@13thfloor.at>]

On Mon, Jul 26, 2004 at 05:33:07PM -0400, Mike Waychison wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> Trond Myklebust wrote:
> > På må , 26/07/2004 klokka 12:29, skreiv John S J Anderson:
> >
> >>  Hi --
> >>
> >>  We're working on migrating to the 2.6 kernel series, and one big
> >>  problem has popped up: we have a number of NFS mounts that are
> >>  mounted read-only in one location and read-write in a distinct
> >>  location (on the same machine). With 2.4 series kernels, this worked
> >>  without issue, but with 2.6, it doesn't: it's not possible to mount
> >>  the same filesystem twice with different options for each mount; the
> >>  two mount points have to share the same mount options.
> >
> > That behaviour is no longer supported as it meant that you would have
> > different superblocks (and hence different out-of-sync caches) between
> > the 2 mountpoint. It is in any case not a behaviour that is supported on
> > any other Linux filesystems.
> 
> How is this any different than having two seperate nfs clients accessing
> the same nfs export?
> 
> > If you want readonly to be an exception, then you will have to move the
> > MS_RDONLY flag from being a superblock option to being a vfsmount
> > option, then propagate that vfsmount information down to all the tests
> > of IS_RDONLY(inode). Not a trivial task, and not one that looms high on
> > my list of priorities...
> 
> What ever happened to the bind ro patches that were floating around a
> couple months ago?
> (http://marc.theaimsgroup.com/?t=107932320200005&r=1&w=2)
> 
> What is left in getting this done?  Just the touch_file bit Viro
> commented on?

started with the noatime/nodiratime stuff for inclusion
but that patch was neither commented nor included, so
I put it on hold ... currently I'm planning to update 
this for 2.6.8 ... we'll see ...

best,
Herbert


> - --
> Mike Waychison
> Sun Microsystems, Inc.
> 1 (650) 352-5299 voice
> 1 (416) 202-8336 voice
> http://www.sun.com
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> NOTICE:  The opinions expressed in this email are held by me,
> and may not represent the views of Sun Microsystems, Inc.
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.2.4 (GNU/Linux)
> 
> iD4DBQFBBXiTdQs4kOxk3/MRAp2CAJ9hLA43GX7breEAuFJp++noSX7hAQCYn7yw
> FXXelAMC/NCetjqwC8Q67g==
> =rQRx
> -----END PGP SIGNATURE-----