From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q6J1wF7q245110 for ; Wed, 18 Jul 2012 20:58:16 -0500 Received: from ipmail06.adl2.internode.on.net (ipmail06.adl2.internode.on.net [150.101.137.129]) by cuda.sgi.com with ESMTP id JaHVKmz1CqsxCFJQ for ; Wed, 18 Jul 2012 18:58:13 -0700 (PDT) Date: Thu, 19 Jul 2012 11:58:09 +1000 From: Dave Chinner Subject: Re: [RFC] xfs: wait for the write of the superblock on unmount Message-ID: <20120719015809.GC23387@dastard> References: <20120717215957.855744999@tinguelysgi.com> <20120718220003.396849822@tinguelysgi.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20120718220003.396849822@tinguelysgi.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: tinguely@sgi.com Cc: xfs@oss.sgi.com On Wed, Jul 18, 2012 at 12:33:58PM -0500, tinguely@sgi.com wrote: > Sorry, I have been distracted away from this regression. This was previously > titled "xfs: synchronously write the superblock on unmount". > > xfs_wait_buftarg() does not wait for the completion of the write of the > uncached superblock. This write can race with the shutdown of the log and > causes a panic if the write does not win the race. > > The log write of the superblock is important for possible recovery, but a > second syncronous write of the same superblock seems redundant. Would just > waiting for the iodone() of the log write before tearing down the log be > enough? Yes. i.e. something like: /* * The superblock buffer is uncached, so xfs_wait_buftarg() * will not wait for it. Hence we need to explicitly wait * for IO completion on the superblock to occur here. */ error = xfs_buf_iowait(mp->m_sb_bp); if (error) AAAAIEEEE! This fix is also needed in xfs_quiesce_attr() for the freeze and ro,remount cases as well. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs