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Date: Tue, 13 Aug 2002 15:09:29 +1000
From: Stephen Rothwell <sfr@canb.auug.org.au>
To: Marcelo Tosatti <marcelo@conectiva.com.br>
Cc: linux-kernel@vger.kernel.org, matthew@wil.cx, michael.kerrisk@gmx.net
Subject: Re: [PATCH] [2.4.20-pre2] File lease fixes
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	<Pine.LNX.4.44.0208122346260.3620-100000@freak.distro.conectiva>
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Hi Marcelo,

On Mon, 12 Aug 2002 23:47:03 -0300 (BRT) Marcelo Tosatti <marcelo@conectiva.com.br> wrote:
>
> On Tue, 13 Aug 2002, Stephen Rothwell wrote:
> 
> >  static inline int get_lease(struct inode *inode, unsigned int mode)
> >  {
> > -	if (inode->i_flock && (inode->i_flock->fl_flags & FL_LEASE))
> > +	if (inode->i_flock)
> >  		return __get_lease(inode, mode);
> >  	return 0;
> >  }
> 
> Why do you remove the FL_LEASE check here?

Because there is a race between checking inode->i_flock and
inode->i_flock->fl_flags which a couple of people have actually
hit ... The check for FL_EASE is done again in __get_lease
but protected by the BKL.

This is just an optimisation and having the check here is only
faster in the case where there is a lock held that is NOT a lease.

This was the race fix provided by Willy.
-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/
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