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

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Date:	Wed, 20 Dec 2006 16:11:58 -0800
From:	Andrew Morton <akpm@...l.org>
To:	Linus Torvalds <torvalds@...l.org>
Cc:	Martin Michlmayr <tbm@...ius.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Hugh Dickins <hugh@...itas.com>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Arjan van de Ven <arjan@...radead.org>,
	Andrei Popa <andrei.popa@...eo.ro>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Florian Weimer <fw@...eb.enyo.de>,
	Marc Haber <mh+linux-kernel@...schlus.de>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Arnd Bergmann <arnd.bergmann@...ibm.com>,
	gordonfarquharson@...il.com,
	"Chen, Kenneth W" <kenneth.w.chen@...el.com>
Subject: Re: [PATCH] mm: fix page_mkclean_one (was: 2.6.19 file content
 corruption on ext3)

On Wed, 20 Dec 2006 15:55:14 -0800 (PST)
Linus Torvalds <torvalds@...l.org> wrote:

> > > @@ -386,12 +399,8 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
> > 
> > invalidate_complete_page2() is pretty gruesome.  We're handling the case
> > where someone went and redirtied the page (and hence its buffers) after the
> > invalidate_inode_pages2() caller (generic_file_direct_IO) synced it to
> > disk.
> > 
> > I'd prefer to just fail the direct-io if someone did that, but then
> > people's tests fail and they whine.
> 
> So with my change, afaik, we will just return EIO to the invalidate, and 
> do the write.

The write's already been done by this stage.

> Which should be ok. In fact, it appears to be the only 
> possibly valid thing to do.
> 
> It really boils down to that same thing: if you remove the dirty bit, 
> there is NO CONCEIVABLE GOOD THING YOU CAN DO EXCEPT FOR:
>  - do the damn IO already ("clear_page_dirty_for_io()")
>  - truncate the page (unmap and destroy it both from page cache AND from 
>    any user-visible filesystem cases)

There's also redirty_page_for_writepage().

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