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Date: Thu, 8 Mar 2007 18:25:50 +0800
From: Fengguang Wu <fengguang.wu@gmail.com>
To: Ram Pai <linuxram@us.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       Suparna Bhattacharya <suparna@in.ibm.com>,
       John Tran <jbtran@ca.ibm.com>, Mike Sullivan <mksully@us.ibm.com>,
       Chris Mason <mason@suse.com>, Steven Pratt <slpratt@austin.ibm.com>,
       Badari Pulavarty <badari@us.ibm.com>, Mingming Cao <mcao@us.ibm.com>,
       Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -mm] readahead: partial sendfile fix
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References: <20070210014049.GA11269@mail.ustc.edu.cn> <1171309751.2891.70.camel@ram.us.ibm.com>
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Ram Pai,

Sorry for the long delay, I was just back from the winter vacation.

On Mon, Feb 12, 2007 at 11:49:10AM -0800, Ram Pai wrote:
> The solution you proposed seems kludgy to me. If you determine that the

I dislike it, either.

> its a restarted aio, then start reading from where readahead had left
> reading from earlier. To me a simple fix is:
> 
> -       if (unlikely(aio_restarted()))
> -               next_index = last_index; /* Avoid repeat readahead */
> 
> +       if (unlikely(aio_restarted()))
> +  		next_index = min(prev_index+1, last_index);
> 
> 
> No? 

Can be even simpler, if we _only_ want to fix the aio case:

+       if (unlikely(aio_restarted()))
+               next_index = prev_index + 1;

Regards,
Wu