linux-kernel - Re: 2.6.xx: NFS: directory motion/cam2 contains a readdir loop

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Date:	Wed, 27 Jul 2011 16:37:01 -0400
From:	Trond Myklebust <Trond.Myklebust@...app.com>
To:	Christoph Hellwig <hch@...radead.org>,
	Bryan Schumaker <bjschuma@...app.com>
Cc:	Justin Piszcz <jpiszcz@...idpixels.com>,
	"J. Bruce Fields" <bfields@...ldses.org>,
	linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
	xfs@....sgi.com
Subject: Re: 2.6.xx: NFS: directory motion/cam2 contains a readdir loop

On Wed, 2011-07-27 at 15:47 -0400, Christoph Hellwig wrote: 
> On Wed, Jul 27, 2011 at 03:44:20PM -0400, Justin Piszcz wrote:
> > 
> > 
> > On Wed, 27 Jul 2011, Christoph Hellwig wrote:
> > 
> > >On Wed, Jul 27, 2011 at 03:35:01PM -0400, Justin Piszcz wrote:
> > >>Currently I do not see any dupes, however I have a script that moves
> > >>images out of the directory once an hour:
> > >>0 * * * * /usr/local/bin/move_to_old2.sh > /dev/null 2>&1
> > >
> > >Do you keep adding files to the directory while you move files out?
> > Yes, otherwise there are too many files in the directory and viewers, e.g.,
> > each geeqie (picture viewer) will use > 4-6GB of memory, so I try to keep
> > it around 5,000 pictures or less.
> > 
> > >What's the rate of additions/removals to the directory?
> > Additions it depends, around 5,000 over a 12hr period, 416/hr, current:
> > 
> > atom:/d1/motion# find cam1|wc
> >    5215    5215  166853
> > atom:/d1/motion# find cam2|wc
> >    5069    5069  162181
> > atom:/d1/motion# find cam3|wc
> >    5594    5594  178981
> > atom:/d1/motion#
> 
> This sounds a lot like xfs simply filling up the directory index slots
> of files that you just moved out with new files, and nfs falsely
> claiming that this is a problem.

Yep. There is an existing bugzilla report for this bug at

   https://bugzilla.kernel.org/show_bug.cgi?id=38572

I have a preliminary patch there that attempts to turn off the loop
detection when the directory is seen to change, however that patch still
appears to have a bug in it, and I haven't had time to figure out what
is wrong yet.

Can you perhaps take a look, Bryan?

Cheers
  Trond
-- 
Trond Myklebust
Linux NFS client maintainer

NetApp
Trond.Myklebust@...app.com
www.netapp.com

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