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Date: Sun, 15 Aug 2004 15:32:11 -0700
From: Andrew Morton <akpm@osdl.org>
To: James Morris <jmorris@redhat.com>
Cc: romieu@fr.zoreil.com, sds@epoch.ncsc.mil, neilb@cse.unsw.edu.au,
       viro@parcelfarce.linux.theplanet.co.uk, linux-kernel@vger.kernel.org
Subject: Re: [PATCH][LIBFS] Move transaction file ops into libfs + cleanup
 (update)
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James Morris <jmorris@redhat.com> wrote:
>
> On Sat, 14 Aug 2004, Francois Romieu wrote:
> 
> > > +static inline void simple_transaction_set(struct file *file, size_t n)
> > > +{
> > > +	struct simple_transaction_argresp *ar = file->private_data;
> > > +	
> > > +	BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
> > > +	mb();
> > > +	ar->size = n;
> > > +}
> > 
> > Could you add the justification for the 'mb' (or the expected effect on the
> > api) as a comment ?
> 
> This ensures that ar->size will really remain zero until ar->data is ready
> for reading.

I updated the patch to include this important detail in a comment. 
Shouldn't it be an smb_mb()?