linux-kernel - Re: [PATCH][RFC][BUG] updating the ctime and mtime time stamps in msync()

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Message-ID: <4df4ef0c0801100840uf84fef6g80e456fc5681193@mail.gmail.com>
Date:	Thu, 10 Jan 2008 19:40:41 +0300
From:	"Anton Salikhmetov" <salikhmetov@...il.com>
To:	"Rik van Riel" <riel@...hat.com>
Cc:	"Jakob Oestergaard" <jakob@...hought.net>, Valdis.Kletnieks@...edu,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][RFC][BUG] updating the ctime and mtime time stamps in msync()

2008/1/10, Rik van Riel <riel@...hat.com>:
> On Thu, 10 Jan 2008 18:56:07 +0300
> "Anton Salikhmetov" <salikhmetov@...il.com> wrote:
>
> > However, I don't see how they will work if there has been
> > something like a sync(2) done after the mmap'd region is
> > modified and the msync call.  When the inode is written out
> > as part of the sync process, I_DIRTY_PAGES will be cleared,
> > thus causing a miss in this code.
> >
> > The I_DIRTY_PAGES check here is good, but I think that there
> > needs to be some code elsewhere too, to catch the case where
> > I_DIRTY_PAGES is being cleared, but the time fields still need
> > to be updated.
>
> Agreed. The mtime and ctime should probably also be updated
> when I_DIRTY_PAGES is cleared.
>
> The alternative would be to remember that the inode had been
> dirty in the past, and have the mtime and ctime updated on
> msync or close - which would be more complex.

Adding the new flag (AS_MCTIME) has been already suggested by Peter
Staubach in his first solution for this bug. Now I understand that the
AS_MCTIME flag is required for fixing the bug.

>
> --
> All rights reversed.
>
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