linux-kernel - Re: rename() contention (BUG?)

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Date:	Thu, 26 Oct 2006 22:37:48 +0100
From:	Al Viro <viro@....linux.org.uk>
To:	Avi Kivity <avi@...o.co.il>
Cc:	Josef Sipek <jsipek@....cs.sunysb.edu>, lkml@...garu.com,
	linux-kernel@...r.kernel.org
Subject: Re: rename() contention (BUG?)

On Thu, Oct 26, 2006 at 11:19:56PM +0200, Avi Kivity wrote:
> Al Viro wrote:
> >On Thu, Oct 26, 2006 at 08:43:34PM +0200, Avi Kivity wrote:
> >  
> >>The changes make the mutex more efficient, but won't decrease the 
> >>contention.  It seems that all renames in one filesystem are serialized, 
> >>and if the renames require I/O (which is certainly the case with nfs), 
> >>rename throughput is severely limited.
> >>    
> >
> >	They are, and for a good reason.  For details see
> >Documentation/filesystems/directory-locking.
> >  
> 
> Is it possible to lock only the common subtree of the two paths?
> 
> Perhaps walk towards the root of the tree, starting with the deeper 
> path, locking one component at a time.  Then walk both paths together 
> locking components ordered by something to avoid deadlock.

Please, read the file mentioned above.
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