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From: Mike Waychison <Michael.Waychison@Sun.COM>
To: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: John S J Anderson <jacobs@genehack.org>,
	linux-kernel@vger.kernel.org,
	Alexander Viro <viro@parcelfarce.linux.theplanet.co.uk>,
	Herbert Poetzl <herbert@13thfloor.at>
Subject: Re: bug with multiple mounts of filesystems in 2.6
Date: Mon, 26 Jul 2004 20:56:56 -0400	[thread overview]
Message-ID: <4105A858.7090209@sun.com> (raw)
In-Reply-To: <1090881327.6809.111.camel@lade.trondhjem.org>

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Trond Myklebust wrote:
> På må , 26/07/2004 klokka 17:33, skreiv Mike Waychison:
>
>
>>How is this any different than having two seperate nfs clients accessing
>>the same nfs export?
>
>
> It isn't, but why do you think that should be a reason for allowing it?
>
> By all means feel free to add "mount --bind -oro" capabilities, but it
> is neither useful nor is it necessary to break the NFS caching model in
> order to do so.
>

Agreed.  The two problems are orthogonal. [1]

As an example where sharing the super_block is wrong (albeit probably
just an oversight) is that the protocols (udp vs tcp) are not compared
in nfs_compare_super.  You could argue that the client fhandles should
be different though, I'm not sure..

Another 'bind mount extension' that would be nice to change at the
vfsmount level may be w/rsize, but that is probably a very intrusive
change for nfs and probably not possible.  Thoughts?

[1] - I haven't tested mounting nfs ro, and then mounting nfs rw using
the bind extensions.  Does nfs make any assumptions about the mount
being ro?

- --
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.
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  reply	other threads:[~2004-07-27  0:58 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-07-26 16:29 bug with multiple mounts of filesystems in 2.6 John S J Anderson
2004-07-26 19:37 ` Trond Myklebust
2004-07-26 21:33   ` Mike Waychison
2004-07-26 22:30     ` Herbert Poetzl
2004-07-26 22:35     ` Trond Myklebust
2004-07-27  0:56       ` Mike Waychison [this message]
2004-07-27  2:51         ` Trond Myklebust

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