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Date: Mon, 17 Dec 2001 13:18:29 -0500
To: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: dzafman@kahuna.cag.cpqcorp.net, linux-kernel@vger.kernel.org,
        Alexander Viro <viro@math.psu.edu>
Subject: Re: NFS client llseek
Message-ID: <20011217181748.GA15970@cs.cmu.edu>
Mail-Followup-To: Trond Myklebust <trond.myklebust@fys.uio.no>,
	dzafman@kahuna.cag.cpqcorp.net, linux-kernel@vger.kernel.org,
	Alexander Viro <viro@math.psu.edu>
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From: Jan Harkes <jaharkes@cs.cmu.edu>
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On Fri, Dec 14, 2001 at 01:51:36PM +0100, Trond Myklebust wrote:
> Just one comment: Isn't it easier to do this in generic_file_llseek()
> itself using inode->i_op->revalidate()? That would make it work for
> coda and smbfs too...

Actually, as far as Coda is concerned this only adds overhead. Coda uses
AFS2 session semantics instead of UNIX semantics, so updates are only
propagated when a file is closed.

Adding this to the generic_file_llseek will force an useless but
expensive upcall (and RPC call to the server) to every seek to check for
an updated i_size while we already know that the i_size of the file
won't have to change until it is closed and reopened.

I guess we're just (mis-)using the revalidate call as a replacement of a
missing call to i_ops->getattr from sys_stat. So perhaps adding the
revalidate to the generic_llseek is fine, but I'll just have to get that
missing getattr call into the tree.

Jan

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