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[209.132.183.28]) by mx.google.com with ESMTPS id v6si3022376qte.364.2019.01.11.03.03.52 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 11 Jan 2019 03:03:52 -0800 (PST) Received-SPF: pass (google.com: domain of ming.lei@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ming.lei@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=ming.lei@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A2DF824C9D; Fri, 11 Jan 2019 11:03:51 +0000 (UTC) Received: from localhost (ovpn-8-28.pek2.redhat.com [10.72.8.28]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8656B27C57; Fri, 11 Jan 2019 11:03:38 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Theodore Ts'o , Omar Sandoval , Sagi Grimberg , Dave Chinner , Kent Overstreet , Mike Snitzer , dm-devel@redhat.com, Alexander Viro , linux-fsdevel@vger.kernel.org, linux-raid@vger.kernel.org, David Sterba , linux-btrfs@vger.kernel.org, "Darrick J . Wong" , linux-xfs@vger.kernel.org, Gao Xiang , Christoph Hellwig , linux-ext4@vger.kernel.org, Coly Li , linux-bcache@vger.kernel.org, Boaz Harrosh , Bob Peterson , cluster-devel@redhat.com, Ming Lei Subject: [PATCH V13 08/19] block: use bio_for_each_bvec() to map sg Date: Fri, 11 Jan 2019 19:01:16 +0800 Message-Id: <20190111110127.21664-9-ming.lei@redhat.com> In-Reply-To: <20190111110127.21664-1-ming.lei@redhat.com> References: <20190111110127.21664-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Fri, 11 Jan 2019 11:03:52 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP It is more efficient to use bio_for_each_bvec() to map sg, meantime we have to consider splitting multipage bvec as done in blk_bio_segment_split(). Reviewed-by: Omar Sandoval Reviewed-by: Christoph Hellwig Signed-off-by: Ming Lei --- block/blk-merge.c | 70 +++++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 50 insertions(+), 20 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index abe1c89c1253..bf736d2b3710 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -460,6 +460,54 @@ static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio, return biovec_phys_mergeable(q, &end_bv, &nxt_bv); } +static struct scatterlist *blk_next_sg(struct scatterlist **sg, + struct scatterlist *sglist) +{ + if (!*sg) + return sglist; + + /* + * If the driver previously mapped a shorter list, we could see a + * termination bit prematurely unless it fully inits the sg table + * on each mapping. We KNOW that there must be more entries here + * or the driver would be buggy, so force clear the termination bit + * to avoid doing a full sg_init_table() in drivers for each command. + */ + sg_unmark_end(*sg); + return sg_next(*sg); +} + +static unsigned blk_bvec_map_sg(struct request_queue *q, + struct bio_vec *bvec, struct scatterlist *sglist, + struct scatterlist **sg) +{ + unsigned nbytes = bvec->bv_len; + unsigned nsegs = 0, total = 0, offset = 0; + + while (nbytes > 0) { + unsigned seg_size; + struct page *pg; + unsigned idx; + + *sg = blk_next_sg(sg, sglist); + + seg_size = get_max_segment_size(q, bvec->bv_offset + total); + seg_size = min(nbytes, seg_size); + + offset = (total + bvec->bv_offset) % PAGE_SIZE; + idx = (total + bvec->bv_offset) / PAGE_SIZE; + pg = nth_page(bvec->bv_page, idx); + + sg_set_page(*sg, pg, seg_size, offset); + + total += seg_size; + nbytes -= seg_size; + nsegs++; + } + + return nsegs; +} + static inline void __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, struct scatterlist *sglist, struct bio_vec *bvprv, @@ -477,25 +525,7 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, (*sg)->length += nbytes; } else { new_segment: - if (!*sg) - *sg = sglist; - else { - /* - * If the driver previously mapped a shorter - * list, we could see a termination bit - * prematurely unless it fully inits the sg - * table on each mapping. We KNOW that there - * must be more entries here or the driver - * would be buggy, so force clear the - * termination bit to avoid doing a full - * sg_init_table() in drivers for each command. - */ - sg_unmark_end(*sg); - *sg = sg_next(*sg); - } - - sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); - (*nsegs)++; + (*nsegs) += blk_bvec_map_sg(q, bvec, sglist, sg); } *bvprv = *bvec; } @@ -517,7 +547,7 @@ static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio, int nsegs = 0; for_each_bio(bio) - bio_for_each_segment(bvec, bio, iter) + bio_for_each_bvec(bvec, bio, iter) __blk_segment_map_sg(q, &bvec, sglist, &bvprv, sg, &nsegs);