Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934697AbbLQHdp (ORCPT ); Thu, 17 Dec 2015 02:33:45 -0500 Received: from mail-pf0-f173.google.com ([209.85.192.173]:33944 "EHLO mail-pf0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934655AbbLQHdb (ORCPT ); Thu, 17 Dec 2015 02:33:31 -0500 From: Baolin Wang To: axboe@kernel.dk, agk@redhat.com, snitzer@redhat.com, dm-devel@redhat.com Cc: neilb@suse.com, dan.j.williams@intel.com, martin.petersen@oracle.com, sagig@mellanox.com, kent.overstreet@gmail.com, keith.busch@intel.com, tj@kernel.org, broonie@kernel.org, arnd@arndb.de, linux-block@vger.kernel.org, linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, baolin.wang@linaro.org Subject: [PATCH v3 1/2] block: Introduce blk_bio_map_sg() to map one bio Date: Thu, 17 Dec 2015 15:32:48 +0800 Message-Id: X-Mailer: git-send-email 1.7.9.5 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2755 Lines: 88 In dm-crypt, it need to map one bio to scatterlist for improving the encryption efficiency. Thus this patch introduces the blk_bio_map_sg() function to map one bio with scatterlists. Signed-off-by: Baolin Wang --- block/blk-merge.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ include/linux/blkdev.h | 3 +++ 2 files changed, 48 insertions(+) diff --git a/block/blk-merge.c b/block/blk-merge.c index de5716d8..281b9e5 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -374,6 +374,51 @@ single_segment: } /* + * map a bio to scatterlist, return number of sg entries setup. + */ +int blk_bio_map_sg(struct request_queue *q, struct bio *bio, + struct scatterlist *sglist, + struct scatterlist **sg) +{ + struct bio_vec bvec, bvprv = { NULL }; + struct bvec_iter iter; + int nsegs, cluster; + + nsegs = 0; + cluster = blk_queue_cluster(q); + + if (bio->bi_rw & REQ_DISCARD) { + /* + * This is a hack - drivers should be neither modifying the + * biovec, nor relying on bi_vcnt - but because of + * blk_add_request_payload(), a discard bio may or may not have + * a payload we need to set up here (thank you Christoph) and + * bi_vcnt is really the only way of telling if we need to. + */ + + if (bio->bi_vcnt) + goto single_segment; + + return 0; + } + + if (bio->bi_rw & REQ_WRITE_SAME) { +single_segment: + *sg = sglist; + bvec = bio_iovec(bio); + sg_set_page(*sg, bvec.bv_page, bvec.bv_len, bvec.bv_offset); + return 1; + } + + bio_for_each_segment(bvec, bio, iter) + __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, + &nsegs, &cluster); + + return nsegs; +} +EXPORT_SYMBOL(blk_bio_map_sg); + +/* * map a request to scatterlist, return number of sg entries setup. Caller * must make sure sg can hold rq->nr_phys_segments entries */ diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 3fe27f8..3ca90ac 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1004,6 +1004,9 @@ extern void blk_queue_flush_queueable(struct request_queue *q, bool queueable); extern struct backing_dev_info *blk_get_backing_dev_info(struct block_device *bdev); extern int blk_rq_map_sg(struct request_queue *, struct request *, struct scatterlist *); +extern int blk_bio_map_sg(struct request_queue *q, struct bio *bio, + struct scatterlist *sglist, + struct scatterlist **sg); extern void blk_dump_rq_flags(struct request *, char *); extern long nr_blockdev_pages(void); -- 1.7.9.5 -- 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/