linux-kernel - Re: splice vs execve lockdep trace.

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Message-ID: <20130716065010.GG11674@dastard>
Date:	Tue, 16 Jul 2013 16:50:11 +1000
From:	Dave Chinner <david@...morbit.com>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Oleg Nesterov <oleg@...hat.com>, Ben Myers <bpm@....com>,
	xfs@....sgi.com
Subject: Re: splice vs execve lockdep trace.

On Tue, Jul 16, 2013 at 07:16:02AM +0100, Al Viro wrote:
> On Tue, Jul 16, 2013 at 04:03:51PM +1000, Dave Chinner wrote:
> 
> > I posted patches to fix this i_mutex/i_iolock inversion a couple of
> > years ago (july 2011):
> > 
> > https://lkml.org/lkml/2011/7/18/4
> > 
> > And V2 was posted here and reviewed (aug 2011):
> > 
> > http://xfs.9218.n7.nabble.com/PATCH-0-2-splice-i-mutex-vs-splice-write-deadlock-V2-tt4072.html#none
> 
> Unless I'm misreading the patch, you end up doing file_remove_suid()
> without holding i_mutex at all...

+       xfs_rw_ilock(ip, XFS_IOLOCK_EXCL);
+       ret = file_remove_suid(out);

Actaully, xfs_rw_ilock() takes the i_mutex due to teh exclusive locking ebing
done, so that's all fine.

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com
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