linux-kernel - Re: [PATCH 2/2][RFC][BUG] msync: updating ctime and mtime at syncing

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Message-Id: <1200130844.7999.12.camel@lappy>
Date:	Sat, 12 Jan 2008 10:40:44 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Anton Salikhmetov <salikhmetov@...il.com>
Cc:	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
Subject: Re: [PATCH 2/2][RFC][BUG] msync: updating ctime and mtime at
	syncing


On Sat, 2008-01-12 at 10:36 +0100, Peter Zijlstra wrote:
> On Fri, 2008-01-11 at 03:44 +0300, Anton Salikhmetov wrote:
> 
> > +/*
> > + * Update the ctime and mtime stamps after checking if they are to be updated.
> > + */
> > +void mapped_file_update_time(struct file *file)
> > +{
> > +	if (test_and_clear_bit(AS_MCTIME, &file->f_mapping->flags)) {
> > +		get_file(file);
> > +		file_update_time(file);
> > +		fput(file);
> > +	}
> > +}
> > +
> 
> I don't think you need the get/put file stuff here, because

BTW, the reason for me noticing this is that if it would be needed there
is a race condition right there, who is to say that the file pointer
you're deref'ing in your test condition isn't a dead one already.

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