linux-kernel - Re: [PATCH] incorrect error handling inside generic_file_direct

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Date:	Tue, 2 Jan 2007 11:17:46 +0000
From:	'Christoph Hellwig' <hch@...radead.org>
To:	"Chen, Kenneth W" <kenneth.w.chen@...el.com>
Cc:	'Christoph Hellwig' <hch@...radead.org>,
	'Andrew Morton' <akpm@...l.org>,
	Dmitriy Monakhov <dmonakhov@...ru>,
	Dmitriy Monakhov <dmonakhov@...nvz.org>,
	linux-kernel@...r.kernel.org,
	Linux Memory Management <linux-mm@...ck.org>,
	devel@...nvz.org, xfs@....sgi.com
Subject: Re: [PATCH]  incorrect error handling inside generic_file_direct_write

On Fri, Dec 15, 2006 at 10:53:18AM -0800, Chen, Kenneth W wrote:
> Christoph Hellwig wrote on Friday, December 15, 2006 2:44 AM
> > So we're doing the sync_page_range once in __generic_file_aio_write
> > with i_mutex held.
> > 
> > 
> > >  	mutex_lock(&inode->i_mutex);
> > > -	ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
> > > -			&iocb->ki_pos);
> > > +	ret = __generic_file_aio_write(iocb, iov, nr_segs, pos);
> > >  	mutex_unlock(&inode->i_mutex);
> > >  
> > >  	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
> > 
> > And then another time after it's unlocked, this seems wrong.
> 
> 
> I didn't invent that mess though.
> 
> I should've ask the question first: in 2.6.20-rc1, generic_file_aio_write
> will call sync_page_range twice, once from __generic_file_aio_write_nolock
> and once within the function itself.  Is it redundant?  Can we delete the
> one in the top level function?  Like the following?

Really?  I'm looking at -rc3 now as -rc1 is rather old and it's definitly
not the case there.  I also can't remember ever doing this - when I
started the generic read/write path untangling I had exactly the same
situation that's now in -rc3:

  - generic_file_aio_write_nolock calls sync_page_range_nolock
  - generic_file_aio_write calls sync_page_range
  - __generic_file_aio_write_nolock doesn't call any sync_page_range variant

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