From: Andi Kleen <ak@suse.de>
Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg)
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [PATCH] [8/18] BKL-removal: Remove BKL from remote_llseek
Date: Mon, 28 Jan 2008 15:10:34 +0100
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Cc: Andrew Morton <akpm@linux-foundation.org>,
       Trond Myklebust <Trond.Myklebust@netapp.com>,
       Steve French <smfrench@gmail.com>, swhiteho@redhat.com,
       sfrench@samba.org, vandrove@vc.cvut.cz, linux-kernel@vger.kernel.org,
       linux-fsdevel@vger.kernel.org
References: <20080127317.043953000@suse.de> <200801281427.36048.ak@suse.de> <20080128133857.6c53ac9f@core>
In-Reply-To: <20080128133857.6c53ac9f@core>
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On Monday 28 January 2008 14:38:57 Alan Cox wrote:
> > Also worse really fixing it would be a major change to the VFS 
> > because of the way ->read/write are defined :/
> 
> I don't see a problem there. ->read and ->write update the passed pointer
> which is not the real f_pos anyway. Just the copies need fixing. 

They are effectually doing a decoupled read/modify/write cycle. e.g.:

A               B

read fpos       

                read fpos

fpos += A       fpos += B
                write fpos


write fpos

So you get overlapping reads. Probably not good.

-Andi
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