Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932493AbZFLNgm (ORCPT ); Fri, 12 Jun 2009 09:36:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1765417AbZFLNaP (ORCPT ); Fri, 12 Jun 2009 09:30:15 -0400 Received: from brick.kernel.dk ([93.163.65.50]:36177 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1765416AbZFLNaM (ORCPT ); Fri, 12 Jun 2009 09:30:12 -0400 Date: Fri, 12 Jun 2009 15:30:14 +0200 From: Jens Axboe To: Jeff Moyer Cc: Kiyoshi Ueda , linux-kernel@vger.kernel.org, device-mapper development , Boaz Harrosh , "Jun'ichi Nomura" Subject: Re: [PATCH block#for-2.6.31] block: add request clone interface (v2) Message-ID: <20090612133014.GK11363@kernel.dk> References: <4A3075B2.9040208@ct.jp.nec.com> <20090611110903.GO11363@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2378 Lines: 60 On Thu, Jun 11 2009, Jeff Moyer wrote: > Jens Axboe writes: > > > On Thu, Jun 11 2009, Kiyoshi Ueda wrote: > >> Hi Jens, > >> > >> This patch adds the following 2 interfaces for request-stacking drivers: > >> > >> - blk_rq_prep_clone(struct request *clone, struct request *orig, > >> struct bio_set *bs, gfp_t gfp_mask, > >> int (*bio_ctr)(struct bio *, struct bio*, void *), > >> void *data) > >> * Clones bios in the original request to the clone request > >> (bio_ctr is called for each cloned bios.) > >> * Copies attributes of the original request to the clone request. > >> The actual data parts (e.g. ->cmd, ->buffer, ->sense) are not > >> copied. > >> > >> - blk_rq_unprep_clone(struct request *clone) > >> * Frees cloned bios from the clone request. > >> > >> Request stacking drivers (e.g. request-based dm) need to make a clone > >> request for a submitted request and dispatch it to other devices. > >> > >> To allocate request for the clone, request stacking drivers may not > >> be able to use blk_get_request() because the allocation may be done > >> in an irq-disabled context. > >> So blk_rq_prep_clone() takes a request allocated by the caller > >> as an argument. > >> > >> For each clone bio in the clone request, request stacking drivers > >> should be able to set up their own completion handler. > >> So blk_rq_prep_clone() takes a callback function which is called > >> for each clone bio, and a pointer for private data which is passed > >> to the callback. > >> > >> NOTE: > >> blk_rq_prep_clone() doesn't copy any actual data of the original > >> request. Pages are shared between original bios and cloned bios. > >> So caller must not complete the original request before the clone > >> request. > > > > This looks good to me now, I've applied it. > > Is blk_rq_unprep_clone really the best name? > ^^^^^^ Probably not, but I'm not very good at coming up with elegant names. Your email should have included a new suggestion :-) FWIW, I don't think the name is THAT bad... -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/