From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:38196 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751838Ab1G0Ura (ORCPT ); Wed, 27 Jul 2011 16:47:30 -0400 Date: Wed, 27 Jul 2011 16:47:24 -0400 From: Christoph Hellwig To: R?diger Meier Cc: Christoph Hellwig , Bryan Schumaker , Justin Piszcz , "J. Bruce Fields" , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, xfs@oss.sgi.com Subject: Re: 2.6.xx: NFS: directory motion/cam2 contains a readdir loop Message-ID: <20110727204724.GA21314@infradead.org> References: <4E306D09.5030704@netapp.com> <20110727200240.GA16054@infradead.org> <201107272227.03265.sweet_f_a@gmx.de> Content-Type: text/plain; charset=us-ascii In-Reply-To: <201107272227.03265.sweet_f_a@gmx.de> Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Wed, Jul 27, 2011 at 10:26:55PM +0200, R?diger Meier wrote: > At the time I've started this thread > http://comments.gmane.org/gmane.linux.nfs/40863 > I had the feeling that the readdir cache changings in 2.6.37 have > something to do with these loop problems. > > After that thread I've accepted that's a general problem with > ext4/dirindex and nfs but seeing it again on xfs with just 5000 files > I'm in doubt again. Two separate issues. For one thing the nfs code simply doesn't seem to handle changing directories very well, and one and a half the Linux NFS server might even send incoherent readdir output in a single protocol reply. Issue two is that the ext3/4 hashed directory format is too simply (not to say dumb) to provide a proper 32-bit linear value for the dirent d_off field. It's not a complex task, and the first relatively simple generation of xfs btree directories couldn't handle it either. The v2 directory format handles it fine, but at the cost of a much more complex codebase.