Re: [malware-list] TALPA - a threat model? well sorta.

From: "J. Bruce Fields" <bfields@fieldses.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Theodore Tso <tytso@mit.edu>, Eric Paris <eparis@redhat.com>,
	tvrtko.ursulin@sophos.com, alan@lxorguk.ukuu.org.uk,
	andi@firstfloor.org, Arjan van de Ven <arjan@infradead.org>,
	linux-kernel@vger.kernel.org, malware-list@lists.printk.net,
	malware-list-bounces@dmesg.printk.net, peterz@infradead.org,
	viro@ZenIV.linux.org.uk
Subject: Re: [malware-list] TALPA - a threat model?  well sorta.
Date: Thu, 14 Aug 2008 17:21:09 -0400	[thread overview]
Message-ID: <20080814212109.GM23859@fieldses.org> (raw)
In-Reply-To: <20080814202039.GA4509@infradead.org>

On Thu, Aug 14, 2008 at 04:20:39PM -0400, Christoph Hellwig wrote:
> On Thu, Aug 14, 2008 at 03:41:11PM -0400, Theodore Tso wrote:
> > We do need a standardized way of enabling it (since it does cost you
> > something in performance, so not everyone will want it on), and a
> > standardized way of reading i_version out to userspace.  Maybe a mount
> > option is the right way to do it, maybe not.
> > 
> > We may want to take this to the linux-fs list and try to get
> > agreements on these points; the main reason why it's not enabled by
> > default in ext4 is because the NFSv4 advanced caching code is in
> > common use (is it even in mainline)?
> 
> I have not yet seen code actually using it at all, neither in mainline
> nor on one of the many nfs development lists.

Oops, I'd love to, and it should be very easy.  How do I find out if
i_version is supported on a given superblock?

There's nothing particularly "advanced" about this, by the way--this is
a very minor variation on the caching model that nfs has always had, and
our nfsv4 server is currently pretty broken without it.

Actually, it's pretty broken even on nfsv2/v3 for filesystems with poor
time resolution.

--b.