From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753547Ab0FDQXz (ORCPT ); Fri, 4 Jun 2010 12:23:55 -0400 Received: from cantor2.suse.de ([195.135.220.15]:56776 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751805Ab0FDQXx (ORCPT ); Fri, 4 Jun 2010 12:23:53 -0400 Date: Fri, 4 Jun 2010 18:23:32 +0200 From: Jan Kara To: Boaz Harrosh Cc: Christof Schmitt , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, lsf10-pc@lists.linuxfoundation.org, Nick Piggin , Al Viro , Chris Mason , James Bottomley , "Martin K. Petersen" , Ric Wheeler , Matthew Wilcox , Vladislav Bolkhovitin , Christoph Hellwig Subject: Re: [LFS/VM TOPIC] Stable pages while IO (was Wrong DIF guard tag on ext2 write) Message-ID: <20100604162332.GF3414@quack.suse.cz> References: <20100531112817.GA16260@schmichrtp.mainz.de.ibm.com> <4C07D3D0.8010500@panasas.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C07D3D0.8010500@panasas.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 03-06-10 19:09:52, Boaz Harrosh wrote: > [Topic] > How to not let pages change while in IO > > [Abstract] > As seen in a long thread on the fsdvel scsi mailing lists. Lots of > people have headaches and sleep less nights because individual pages > can change while in IO and/or DMA. Though each one as slightly different > needs, the mechanics look to be the same. Hmm, I don't think it's really about "how to not let pages change" - that is doable by using wait_on_page_writeback() in ->page_mkwrite and ->write_begin. I think the discussion is more about whether we should do it or whether we should rechecksum and resubmit IO in case of checksum failure as Nick proposed... Honza > People that care: > - Mirror and RAID people that need on disk consistency. > - Network storage that wants data checksum. > - DIF/DIX people > - ... > > I for one know nothing of the subject but am a RAID person and would > like a solution that does not force me to copy the complete data load. > > Please lets get all the VM VFS and drivers people in one room and see > if we can have a Linux solution to this problem -- Jan Kara SUSE Labs, CR