Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762772AbZFKLJR (ORCPT ); Thu, 11 Jun 2009 07:09:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755444AbZFKLJD (ORCPT ); Thu, 11 Jun 2009 07:09:03 -0400 Received: from brick.kernel.dk ([93.163.65.50]:46158 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752841AbZFKLJB (ORCPT ); Thu, 11 Jun 2009 07:09:01 -0400 Date: Thu, 11 Jun 2009 13:09:03 +0200 From: Jens Axboe To: Kiyoshi Ueda Cc: 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: <20090611110903.GO11363@kernel.dk> References: <4A3075B2.9040208@ct.jp.nec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A3075B2.9040208@ct.jp.nec.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1932 Lines: 49 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. -- 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/