linux-kernel - Re: [PATCH] mm: fix page_mkclean_one (was: 2.6.19 file content corruption on ext3)

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Message-Id: <20061224005752.937493c8.akpm@osdl.org>
Date:	Sun, 24 Dec 2006 00:57:52 -0800
From:	Andrew Morton <akpm@...l.org>
To:	Linus Torvalds <torvalds@...l.org>
Cc:	Gordon Farquharson <gordonfarquharson@...il.com>,
	Martin Michlmayr <tbm@...ius.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andrei Popa <andrei.popa@...eo.ro>,
	Hugh Dickins <hugh@...itas.com>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Arjan van de Ven <arjan@...radead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: fix page_mkclean_one (was: 2.6.19 file content
 corruption on ext3)

On Sun, 24 Dec 2006 00:43:54 -0800 (PST)
Linus Torvalds <torvalds@...l.org> wrote:

> I now _suspect_ that we're talking about something like
> 
>  - we started a writeout. The IO is still pending, and the page was 
>    marked clean and is now in the "writeback" phase.
>  - a write happens to the page, and the page gets marked dirty again. 
>    Marking the page dirty also marks all the _buffers_ in the page dirty, 
>    but they were actually already dirty, because the IO hasn't completed 
>    yet.
>  - the IO from the _previous_ write completes, and marks the buffers clean 
>    again.

Some things for the testers to try, please:

- mount the fs with ext2 with the no-buffer-head option.  That means either:

  grub.conf:  rootfstype=ext2 rootflags=nobh
  /etc/fstab: ext2 nobh

- mount the fs with ext3 data=writeback, nobh

  grub.conf:  rootfstype=ext3 rootflags=nobh,data=writeback  (I hope this works)
  /etc/fstab: ext2 data=writeback,nobh

if that still fails we can rule out buffer_head funnies.

-
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