Path: Home.Lunix!not-for-mail
Subject: Re: PROBLEM: multiple mount of devices possible 2.4.0-test1 -
    2.4.0-test13-pre4
Date: Sun, 31 Dec 2000 03:18:21 +0000 (UTC)
Organization: lunix confusion services
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From: linux-kernel@ton.iguana.be (Ton Hospel)
To: linux-kernel@vger.kernel.org
Reply-To: linux-kernel@ton.iguana.be (Ton Hospel)
Sender: linux-kernel-owner@vger.kernel.org

In article <Pine.GSO.4.21.0012301829190.4082-100000@weyl.math.psu.edu>,
	Alexander Viro <viro@math.psu.edu> writes:
> On Sat, 30 Dec 2000, Ton Hospel wrote:
> 
>> It should still need a special flag or something, since it's
>> impossible for userspace to check this atomically.
> 
> To check _what_? Having the same tree mounted in several places is
> allowed. End of story. Atomicity of any kind is a non-issue - if you
> have processes that do not cooperate and do random mounts you are
> getting exactly what you are asking for.
> 

I wasn't talking about mounting the same device on different mount points.
If you?ask for that, it's good that you nowadays you can get that (though
even there it might be a good idea to let the filesystem say if it can
support that or not)

I was talking about avoiding that the same device gets multiple mounted 
at the SAME place, e.g. when doing mount -a, which is often used as a
quick way to get the new entries in /etc/fstab

That would also be no problem if there were a standard about e.g. always
flocking /etc/mtab. But as far as I know there isn't such a standard.
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