linux-kernel - Re: mtime updates for mmapped files.

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Date:	Wed, 16 Jan 2008 13:30:52 +0100
From:	Rogier Wolff <R.E.Wolff@...Wizard.nl>
To:	Anton Salikhmetov <salikhmetov@...il.com>
Cc:	Rogier Wolff <R.E.Wolff@...wizard.nl>, linux-kernel@...r.kernel.org
Subject: Re: mtime updates for mmapped files.

On Wed, Jan 16, 2008 at 02:22:49PM +0300, Anton Salikhmetov wrote:
> Unfortunately, this issue has not been fully fixed yet.
> 
> My last attempt (http://lkml.org/lkml/2008/1/15/202) to solve
> this problem has a couple of drawbacks:
> 
> 1) calling a possibly sleeping function from atomic context -
> I've already corrected this;
> 
> 2) there's a very special case with retouching the memory-mapped data
> after a call to msync() with MS_ASYNC.
 
> I'm still working on the latter case, but I guess that I have found
> a solution.
 
> If you badly need a quick fix, I can send my working unreleased
> patch to you.  I reckon that your particular problem will be fixed
> by this patch.  Let me know if you want that.

No need. Thanks for the offer. 

> However, if your application calls msync() with the MS_ASYNC flag,
> it's better to wait a little bit more - I'll release the next version
> of my solution
> shortly.

My application calls "exit" (*). My workaround was to type

	touch <destfile>

to get things to work. In my situation, I was worried about the more
general case, and not really about my personal situation.

I could integrate the "touch <destfile>" into my application, but I
think it is the OS's duty to do this for me. This would be the easiest
non-manual fix for me.

	Roger.

(*) So please check that: 
	- mmap file
	- change mmapped area
	- exit
also works (modifies the timestamp). 

-- 
** R.E.Wolff@...Wizard.nl ** http://www.BitWizard.nl/ ** +31-15-2600998 **
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