linux-kernel - Re: [RFC][PATCH] mm: write_cache

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Date:	Mon, 14 Sep 2009 18:44:47 +0300
From:	Artem Bityutskiy <dedekind1@...il.com>
To:	Nick Piggin <npiggin@...e.de>
Cc:	chris.mason@...cle.com, david@...morbit.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Bityutskiy Artem (Nokia-M/Helsinki)" <Artem.Bityutskiy@...ia.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC][PATCH] mm: write_cache_pages be more sequential

On Mon, 2009-09-07 at 17:07 +0300, Adrian Hunter wrote:
> From 6f3bb7c26936c45d810048f59c369e8d5a5623fc Mon Sep 17 00:00:00 2001
> From: Adrian Hunter <adrian.hunter@...ia.com>
> Date: Mon, 7 Sep 2009 10:49:11 +0300
> Subject: [PATCH] mm: write_cache_pages be more sequential
> 
> If a file is written to sequentially, then writeback
> should write the pages sequentially also.  However,
> that does not always happen.  For example:
> 
> 1) user writes pages 0, 1 and 2 but 2 is incomplete
> 2) write_cache_pages writes pages 0, 1 and 2 and sets
> writeback_index to 3
> 3) user finishes writing page 2 and writes pages 3 and 4
> 4) write_cache_pages writes pages 3 and 4, and then cycles
> back and writes page 2 again.
> 
> So the pages are written out in the order 0, 1, 2, 3 ,4 ,2
> instead of 0, 1, 2, 2, 3, 4.
> 
> This situation was noticed on UBIFS because it writes
> directly from writepage.  Hence if there is an unexpected
> power-loss, a file will end up with a hole even though
> the file was written sequentially by the user.
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@...ia.com>

I wonder, who would merge this patch?

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)

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