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

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Message-Id: <E1JFvgx-0000zz-2C@pomaz-ex.szeredi.hu>
Date:	Fri, 18 Jan 2008 19:11:47 +0100
From:	Miklos Szeredi <miklos@...redi.hu>
To:	torvalds@...ux-foundation.org
CC:	peterz@...radead.org, miklos@...redi.hu, salikhmetov@...il.com,
	linux-mm@...ck.org, jakob@...hought.net,
	linux-kernel@...r.kernel.org, valdis.kletnieks@...edu,
	riel@...hat.com, 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

> 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?

Miklos
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