linux-kernel - Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapped files

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Date:	Fri, 18 Jan 2008 13:28:50 -0500
From:	Rik van Riel <riel@...hat.com>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	torvalds@...ux-foundation.org, peterz@...radead.org,
	miklos@...redi.hu, salikhmetov@...il.com, linux-mm@...ck.org,
	jakob@...hought.net, linux-kernel@...r.kernel.org,
	valdis.kletnieks@...edu, ksm@...dk, staubach@...hat.com,
	jesper.juhl@...il.com, akpm@...ux-foundation.org,
	protasnb@...il.com, r.e.wolff@...wizard.nl,
	hidave.darkstar@...il.com, hch@...radead.org
Subject: Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapped
 files

On Fri, 18 Jan 2008 19:11:47 +0100
Miklos Szeredi <miklos@...redi.hu> wrote:

> > And even in that four-liner, I suspect that the *last* two lines are 
> > actually incorrect: there's no point in updating the file time when the 
> > page *becomes* dirty,
> 
> Actually all four lines do that.  The first two for a write access on
> a present, read-only pte, the other two for a write on a non-present
> pte.
> 
> > we should update the file time when it is marked 
> > clean, and "msync(MS_SYNC)" should update it as part of *that*.
> 
> That would need a new page flag (PG_mmap_dirty?).  Do we have one
> available?

I thought the page writing stuff looked at (and cleared) the pte
dirty bit, too?

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