From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id o1HJSLJW255077 for ; Wed, 17 Feb 2010 13:28:23 -0600 Received: from bombadil.infradead.org (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 3F9501DA64A for ; Wed, 17 Feb 2010 11:29:39 -0800 (PST) Received: from bombadil.infradead.org (bombadil.infradead.org [18.85.46.34]) by cuda.sgi.com with ESMTP id 24GL81T2I6wXiBD3 for ; Wed, 17 Feb 2010 11:29:39 -0800 (PST) Date: Wed, 17 Feb 2010 14:29:38 -0500 From: Christoph Hellwig Subject: Re: [PATCH] xfs: Non-blocking inode locking in IO completion Message-ID: <20100217192938.GA14015@infradead.org> References: <1266384989-28928-1-git-send-email-david@fromorbit.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1266384989-28928-1-git-send-email-david@fromorbit.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Dave Chinner Cc: xfs@oss.sgi.com On Wed, Feb 17, 2010 at 04:36:29PM +1100, Dave Chinner wrote: > The introduction of barriers to DM loop devices (e.g. dm-crypt) has > created a new IO order completion dependency that XFS does not > handle. That is, the completion of log IOs (which have barriers) in > the loop filesystem are now dependent on completion of data IO in > the backing filesystem. I don't think dm belongs into the picture here at all. The problem is simply with the loop device, which sits below dm-crypt in the bugzilla reports. The loop device in SuSE (and for a short time in mainline until we saw unexplainable XFS lockups) implements barriers using fsync. Now that fsync turns a log I/O that issues a barrier in the XFS filesystem inside the loop device into a data I/O the backing filesystem. With this the rest of your description applies again. The patch looks good to me - while I hate introducing random delay() calls I don't really see a way around this. Reviewed-by: Christoph Hellwig _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs