From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933016AbcFCOir (ORCPT ); Fri, 3 Jun 2016 10:38:47 -0400 Received: from mail-io0-f170.google.com ([209.85.223.170]:34087 "EHLO mail-io0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752621AbcFCOio (ORCPT ); Fri, 3 Jun 2016 10:38:44 -0400 Subject: Re: [RFC v2 1/3] block: Introduce blk_bio_map_sg() to map one bio To: Baolin Wang , agk@redhat.com, snitzer@redhat.com, dm-devel@redhat.com, herbert@gondor.apana.org.au, davem@davemloft.net References: <2f0f6811938dafd14c6c7b1dbe8fbabfdcbb19c1.1464346333.git.baolin.wang@linaro.org> Cc: ebiggers3@gmail.com, js1304@gmail.com, tadeusz.struk@intel.com, smueller@chronox.de, standby24x7@gmail.com, shli@kernel.org, dan.j.williams@intel.com, martin.petersen@oracle.com, sagig@mellanox.com, kent.overstreet@gmail.com, keith.busch@intel.com, tj@kernel.org, ming.lei@canonical.com, broonie@kernel.org, arnd@arndb.de, linux-crypto@vger.kernel.org, linux-block@vger.kernel.org, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org From: Jens Axboe Message-ID: <57519670.6050306@kernel.dk> Date: Fri, 3 Jun 2016 08:38:40 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <2f0f6811938dafd14c6c7b1dbe8fbabfdcbb19c1.1464346333.git.baolin.wang@linaro.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/27/2016 05:11 AM, Baolin Wang wrote: > +/* > + * Map a bio to scatterlist, return number of sg entries setup. Caller must > + * make sure sg can hold bio segments entries. > + */ > +int blk_bio_map_sg(struct request_queue *q, struct bio *bio, > + struct scatterlist *sglist) > +{ > + struct scatterlist *sg = NULL; > + int nsegs = 0; > + > + if (bio) > + nsegs = __blk_bios_map_sg(q, bio, sglist, &sg, true); > + > + if (sg) > + sg_mark_end(sg); Put that if (sg) inside the if (bio) section, 'sg' isn't going to be non-NULL outside of that. Additionally, who would call this with a NULL bio? That seems odd, I'd get rid of that check completely. -- Jens Axboe