From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757235Ab0ICKbi (ORCPT ); Fri, 3 Sep 2010 06:31:38 -0400 Received: from TYO201.gate.nec.co.jp ([202.32.8.193]:34347 "EHLO tyo201.gate.nec.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756972Ab0ICKbf (ORCPT ); Fri, 3 Sep 2010 06:31:35 -0400 Message-ID: <4C80CDC6.8060100@ct.jp.nec.com> Date: Fri, 03 Sep 2010 19:28:22 +0900 From: Kiyoshi Ueda User-Agent: Thunderbird 2.0.0.23 (X11/20090825) MIME-Version: 1.0 To: Tejun Heo CC: Mike Snitzer , jaxboe@fusionio.com, j-nomura@ce.jp.nec.com, jamie@shareable.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-raid@vger.kernel.org, hch@lst.de Subject: Re: [PATCH] block: make sure FSEQ_DATA request has the same rq_disk as the original References: <1283162296-13650-1-git-send-email-tj@kernel.org> <1283162296-13650-5-git-send-email-tj@kernel.org> <20100830132836.GB5283@redhat.com> <4C7BB932.1070405@kernel.org> <4C7BD202.4040700@kernel.org> <4C7DFD8F.6070200@ct.jp.nec.com> <4C7FE251.2020003@kernel.org> <4C808BF8.7060402@ct.jp.nec.com> <4C80C0D6.4030405@kernel.org> In-Reply-To: <4C80C0D6.4030405@kernel.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Tejun, On 09/03/2010 06:33 PM +0900, Tejun Heo wrote: > On 09/03/2010 07:47 AM, Kiyoshi Ueda wrote: >> By the way, I had been considering a block-layer interface which remaps >> struct request and its bios to a block device such as: >> void blk_remap_request(struct request *rq, struct block_device *bdev) >> { >> rq->rq_disk = bdev->bd_disk; >> >> __rq_for_each_bio(bio, rq) { >> bio->bi_bdev = bdev->bd_disk; >> } >> } >> >> If there is such an interface and remapping drivers use it, then these >> kind of issues may be avoided in the future. > > I think the problem is more with request initialization. After all, > once bios are packed into a request, they are (or at least should be) > just data containers. We now have multiple request init paths in > block layer and different ones initialize different subsets and it's > not very clear which fields are supposed to be initialized to what by > whom. > > But yeah I agree removing discrepancy between request and bio would be > nice to have too. It's not really remapping tho. Maybe just > blk_set_rq_q() or something like that (it should also set rq->q)? Thank you for pointing it. Yes, the interface should also set rq->q. About the naming of the interface, blk_set_ sounds reasonable to me. But does blk_set_rq_q() take request and queue as arguments? Then, I'm afraid we can't find bdev for bio from given queue. Thanks, Kiyoshi Ueda