linux-kernel - Re: [PATCH 09/11] sysfs: Push file_update_time() into bin_page

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Date:	Mon, 20 Feb 2012 12:00:06 +0100
From:	Jan Kara <jack@...e.cz>
To:	Alex Elder <elder@...amhost.com>
Cc:	Jan Kara <jack@...e.cz>, LKML <linux-kernel@...r.kernel.org>,
	linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Eric Sandeen <sandeen@...hat.com>,
	Dave Chinner <david@...morbit.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH 09/11] sysfs: Push file_update_time() into
 bin_page_mkwrite()

On Thu 16-02-12 13:04:44, Alex Elder wrote:
> On Thu, 2012-02-16 at 14:46 +0100, Jan Kara wrote:
> > CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> > Signed-off-by: Jan Kara <jack@...e.cz>
> > ---
> >  fs/sysfs/bin.c |    2 ++
> >  1 files changed, 2 insertions(+), 0 deletions(-)
> > 
> > diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
> > index a475983..6ceb16f 100644
> > --- a/fs/sysfs/bin.c
> > +++ b/fs/sysfs/bin.c
> > @@ -225,6 +225,8 @@ static int bin_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
> >  	if (!sysfs_get_active(attr_sd))
> >  		return VM_FAULT_SIGBUS;
> >  
> > +	file_update_time(file);
> > +
> >  	ret = 0;
> >  	if (bb->vm_ops->page_mkwrite)
> >  		ret = bb->vm_ops->page_mkwrite(vma, vmf);
> 
> If the filesystem's page_mkwrite() function is responsible
> for updating the time, can't the call to file_update_time()
> here be conditional?
> 
> I.e:
> 	ret = 0;
> 	if (bb->vm_ops->page_mkwrite)
>  		ret = bb->vm_ops->page_mkwrite(vma, vmf);
> 	else
> 		file_update_time(file);
  Hmm, I didn't look previously where do we get bb->vm_ops. It seems they
are inherited from vma->vm_ops so what you suggest should be safe without
any further changes. So I can do that if someone who understands the sysfs
code likes it more.

								Honza
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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