From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Sun, 24 Aug 2008 20:54:28 -0700 (PDT) Received: from cuda.sgi.com ([192.48.176.15]) by oss.sgi.com (8.12.11.20060308/8.12.11/SuSE Linux 0.7) with ESMTP id m7P3sP25030847 for ; Sun, 24 Aug 2008 20:54:25 -0700 Received: from ipmail01.adl6.internode.on.net (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 48C521A3F54F for ; Sun, 24 Aug 2008 20:55:47 -0700 (PDT) Received: from ipmail01.adl6.internode.on.net (ipmail01.adl6.internode.on.net [203.16.214.146]) by cuda.sgi.com with ESMTP id DTjUunKGlkAswP0S for ; Sun, 24 Aug 2008 20:55:47 -0700 (PDT) Date: Mon, 25 Aug 2008 13:55:42 +1000 From: Dave Chinner Subject: Re: [2.6.27-rc4] XFS i_lock vs i_iolock... Message-ID: <20080825035542.GR5706@disturbed> References: <6278d2220808221412x28f4ac5dl508884c8030b364a@mail.gmail.com> <20080825010213.GO5706@disturbed> <48B21507.9050708@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48B21507.9050708@sgi.com> Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: Lachlan McIlroy Cc: Daniel J Blueman , Linux Kernel , xfs@oss.sgi.com, hch@lst.de On Mon, Aug 25, 2008 at 12:12:23PM +1000, Lachlan McIlroy wrote: > Dave Chinner wrote: >> On Fri, Aug 22, 2008 at 10:12:59PM +0100, Daniel J Blueman wrote: >>> On 2.6.27-rc4 with various debug options enabled, lockdep claims lock >>> ordering issues with XFS [1] - easiest reproducer is just running >>> xfs_fsr. Mount options I was using were >>> 'nobarrier,noatime,nodiratime'. >>> >>> Thanks, >>> Daniel >>> >>> --- [1] >>> >>> ======================================================= >>> [ INFO: possible circular locking dependency detected ] >>> 2.6.27-rc4-224c #1 >>> ------------------------------------------------------- >>> xfs_fsr/5763 is trying to acquire lock: >>> (&(&ip->i_lock)->mr_lock/2){--..}, at: [] xfs_ilock+0x8c/0xb0 >>> >>> but task is already holding lock: >>> (&(&ip->i_iolock)->mr_lock/3){--..}, at: [] >>> xfs_ilock+0xa5/0xb0 >> >> False positive. We do: >> >> xfs_lock_two_inodes(ip, tip, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL); > > Why not just change the above line to two lines: > xfs_lock_two_inodes(ip, tip, XFS_IOLOCK_EXCL); > xfs_lock_two_inodes(ip, tip, XFS_ILOCK_EXCL); Yeah, that'd work, but it implllies that we no longer allow xfs_lock_two_inodes() to take both inode locks at once. It would need a comment blaming^Wexplaining why lockdep requires us to do this, and then debug code in xfs_lock_two_inodes() to catch this when someone makes this mistake again in the future. Cheers, Dave. -- Dave Chinner david@fromorbit.com