From: Christoph Hellwig <hch@infradead.org>
To: Theodore Tso <tytso@mit.edu>,
Jan Engelhardt <jengelh@linux01.gwdg.de>,
Christoph Hellwig <hch@lst.de>,
akpm@osdl.org, haveblue@us.ibm.com,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH[RFC] kill sysrq-u (emergency remount r/o)
Date: Tue, 6 Feb 2007 09:44:38 +0000 [thread overview]
Message-ID: <20070206094438.GA5328@infradead.org> (raw)
In-Reply-To: <20070206031744.GA11018@thunk.org>
On Mon, Feb 05, 2007 at 10:17:44PM -0500, Theodore Tso wrote:
> > sysrq+u is helpful. It is like \( sysrq+s && make sure no further writes
> > go to disk \).
>
> I agree it is useful, but if we're going to do it we really should do
> it right. We should have real revoke() functionality on file
> descriptors, which revokes all of the mmap()'s (any attempt to write
> into a previously read/write mmap will cause a SEGV) as well as
> changing f_mode, and then use that to implement emergency read-only
> remount.
Revoke is only part of it. What we really need is proper forced unmount
support. That means revoking any kind of userspace access, blocking new
access and making sure the ondisk image is coherent. This would definitly
be a useful feature, but it's a lot of work.
next prev parent reply other threads:[~2007-02-06 9:45 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-05 17:32 [PATCH[RFC] kill sysrq-u (emergency remount r/o) Christoph Hellwig
2007-02-05 17:34 ` [PATCH[RFC] don't force remount in " Christoph Hellwig
2007-02-05 20:40 ` [PATCH[RFC] kill " Jan Engelhardt
2007-02-06 3:17 ` Theodore Tso
2007-02-06 9:44 ` Christoph Hellwig [this message]
2007-02-06 0:15 ` Eric W. Biederman
2007-02-06 0:45 ` Nigel Cunningham
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