From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Chinner Subject: Re: [PATCH 0/4] Fix filesystem freezing Date: Thu, 12 Jan 2012 13:48:41 +1100 Message-ID: <20120112024841.GB2806@dastard> References: <1326331253-6497-1-git-send-email-jack@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, LKML , linux-ext4@vger.kernel.org, xfs@oss.sgi.com, Eric Sandeen , Dave Chinner , Surbhi Palande , Kamal Mostafa , Christoph Hellwig To: Jan Kara Return-path: Received: from ipmail07.adl2.internode.on.net ([150.101.137.131]:36286 "EHLO ipmail07.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751358Ab2ALCsp (ORCPT ); Wed, 11 Jan 2012 21:48:45 -0500 Content-Disposition: inline In-Reply-To: <1326331253-6497-1-git-send-email-jack@suse.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Thu, Jan 12, 2012 at 02:20:49AM +0100, Jan Kara wrote: > > Hello, > > filesystem freezing is currently racy and thus we can end up with dirty data > on frozen filesystem (see changelog of the first patch for detailed race > description and proposed fix). This patch series aims at fixing this. It only fixes the dirty data race (i.e. SB_FREEZE_WRITE). The same race conditions exist for SB_FREEZE_TRANS on XFS, and so need the same fix. That race has had one previous attempt at fixing it in XFS but that's not possible: b2ce397 Revert "xfs: fix filesystsem freeze race in xfs_trans_alloc" 7a249cf xfs: fix filesystsem freeze race in xfs_trans_alloc It was looking at that problem earlier today that lead to the solution Eric proposed. Essentially the method in these patches needs to replace the xfs specifc m_active_trans counter and delay during ->fs_freeze to prevent that race condition.... Cheers, Dave. -- Dave Chinner david@fromorbit.com