From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754994AbaAHHOs (ORCPT ); Wed, 8 Jan 2014 02:14:48 -0500 Received: from cantor2.suse.de ([195.135.220.15]:47859 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750790AbaAHHOh (ORCPT ); Wed, 8 Jan 2014 02:14:37 -0500 Message-ID: <52CCFADB.6080909@suse.de> Date: Wed, 08 Jan 2014 08:14:35 +0100 From: Hannes Reinecke User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: "Martin K. Petersen" CC: "Darrick J. Wong" , chuck.lever@oracle.com, Christoph Hellwig , Jens Axboe , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Subject: Re: status of block-integrity References: <20131222192128.GA28532@infradead.org> <52C6D0DB.1050906@suse.de> <20140107013646.GB10297@birch.djwong.org> <52CBAA1B.7000509@suse.de> In-Reply-To: X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/07/2014 10:43 PM, Martin K. Petersen wrote: >>>>>> "Hannes" == Hannes Reinecke writes: > > Hannes> Plus (as hch rightly pointed out) as there is no defined > Hannes> userland interface the question is why we bother with all the > Hannes> DIX stuff in the block layer. > > Because it catches problems in the path between block layer and HBA > ASIC? FWIW, we find more issues there than we do between initiator and > target. > But how should it do that exactly? As there is no user (apart from oracleasm) no-one can attach protection information to any data, so even the most dedicated admin cannot exercise this path, let alone find issues here. > API issues aside, another reason adoption has been slow is that very few > applications truly care about this stuff. The current approach in which > data is protected when the I/O is submitted by the filesystem is good > enough for most things. Saves the filesystem people the trouble of > dealing with it too. > > In reality there are only a handful of applications that would actually > benefit from an explicit userland API. Mostly in the database > department. All the potential consumers of an interface I talked to > wanted to use aio so that's why we've focused our efforts there. > aio is perfectly fine; all I care is to have _any_ way of feeding protection information into the kernel. > Both Darrick and I have been busy with other projects the last little > while. I'll start looking at this again when I'm done with copy > offload... > Speaking of which, are there any patches? Doug Gilbert and I are currently discussing LID4 / ROD Token copy for sg3_utils and the block layer, so any patches would be very helpful here. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)