From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA301C43441 for ; Fri, 9 Nov 2018 16:26:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B26EB20825 for ; Fri, 9 Nov 2018 16:26:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B26EB20825 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728586AbeKJCIF (ORCPT ); Fri, 9 Nov 2018 21:08:05 -0500 Received: from mx1.redhat.com ([209.132.183.28]:64658 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727828AbeKJCIF (ORCPT ); Fri, 9 Nov 2018 21:08:05 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 12C8D3082142; Fri, 9 Nov 2018 16:26:48 +0000 (UTC) Received: from localhost (ovpn-8-16.pek2.redhat.com [10.72.8.16]) by smtp.corp.redhat.com (Postfix) with ESMTP id AD5905C21E; Fri, 9 Nov 2018 16:26:43 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Ming Lei , Christoph Hellwig Subject: [PATCH V8 03/18] block: use bio_for_each_bvec() to compute multi-page bvec count Date: Sat, 10 Nov 2018 00:25:55 +0800 Message-Id: <20181109162610.18981-4-ming.lei@redhat.com> In-Reply-To: <20181109162610.18981-1-ming.lei@redhat.com> References: <20181109162610.18981-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Fri, 09 Nov 2018 16:26:48 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org First it is more efficient to use bio_for_each_bvec() in both blk_bio_segment_split() and __blk_recalc_rq_segments() to compute how many multi-page bvecs there are in the bio. Secondly once bio_for_each_bvec() is used, the bvec may need to be splitted because its length can be very longer than max segment size, so we have to split the big bvec into several segments. Thirdly when splitting multi-page bvec into segments, the max segment limit may be reached, so the bio split need to be considered under this situation too. Cc: Christoph Hellwig Signed-off-by: Ming Lei --- block/blk-merge.c | 90 ++++++++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 76 insertions(+), 14 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index 91b2af332a84..6f7deb94a23f 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -160,6 +160,62 @@ static inline unsigned get_max_io_size(struct request_queue *q, return sectors; } +/* + * Split the bvec @bv into segments, and update all kinds of + * variables. + */ +static bool bvec_split_segs(struct request_queue *q, struct bio_vec *bv, + unsigned *nsegs, unsigned *last_seg_size, + unsigned *front_seg_size, unsigned *sectors) +{ + bool need_split = false; + unsigned len = bv->bv_len; + unsigned total_len = 0; + unsigned new_nsegs = 0, seg_size = 0; + + if ((*nsegs >= queue_max_segments(q)) || !len) + return need_split; + + /* + * Multipage bvec may be too big to hold in one segment, + * so the current bvec has to be splitted as multiple + * segments. + */ + while (new_nsegs + *nsegs < queue_max_segments(q)) { + seg_size = min(queue_max_segment_size(q), len); + + new_nsegs++; + total_len += seg_size; + len -= seg_size; + + if ((queue_virt_boundary(q) && ((bv->bv_offset + + total_len) & queue_virt_boundary(q))) || !len) + break; + } + + /* split in the middle of the bvec */ + if (len) + need_split = true; + + /* update front segment size */ + if (!*nsegs) { + unsigned first_seg_size = seg_size; + + if (new_nsegs > 1) + first_seg_size = queue_max_segment_size(q); + if (*front_seg_size < first_seg_size) + *front_seg_size = first_seg_size; + } + + /* update other varibles */ + *last_seg_size = seg_size; + *nsegs += new_nsegs; + if (sectors) + *sectors += total_len >> 9; + + return need_split; +} + static struct bio *blk_bio_segment_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, @@ -173,7 +229,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, struct bio *new = NULL; const unsigned max_sectors = get_max_io_size(q, bio); - bio_for_each_segment(bv, bio, iter) { + bio_for_each_bvec(bv, bio, iter) { /* * If the queue doesn't support SG gaps and adding this * offset would create a gap, disallow it. @@ -188,8 +244,12 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, */ if (nsegs < queue_max_segments(q) && sectors < max_sectors) { - nsegs++; - sectors = max_sectors; + /* split in the middle of bvec */ + bv.bv_len = (max_sectors - sectors) << 9; + bvec_split_segs(q, &bv, &nsegs, + &seg_size, + &front_seg_size, + §ors); } goto split; } @@ -214,11 +274,12 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, if (nsegs == 1 && seg_size > front_seg_size) front_seg_size = seg_size; - nsegs++; bvprv = bv; bvprvp = &bvprv; - seg_size = bv.bv_len; - sectors += bv.bv_len >> 9; + + if (bvec_split_segs(q, &bv, &nsegs, &seg_size, + &front_seg_size, §ors)) + goto split; } @@ -296,6 +357,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, struct bio_vec bv, bvprv = { NULL }; int cluster, prev = 0; unsigned int seg_size, nr_phys_segs; + unsigned front_seg_size = bio->bi_seg_front_size; struct bio *fbio, *bbio; struct bvec_iter iter; @@ -316,7 +378,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, seg_size = 0; nr_phys_segs = 0; for_each_bio(bio) { - bio_for_each_segment(bv, bio, iter) { + bio_for_each_bvec(bv, bio, iter) { /* * If SG merging is disabled, each bio vector is * a segment @@ -336,20 +398,20 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, continue; } new_segment: - if (nr_phys_segs == 1 && seg_size > - fbio->bi_seg_front_size) - fbio->bi_seg_front_size = seg_size; + if (nr_phys_segs == 1 && seg_size > front_seg_size) + front_seg_size = seg_size; - nr_phys_segs++; bvprv = bv; prev = 1; - seg_size = bv.bv_len; + bvec_split_segs(q, &bv, &nr_phys_segs, &seg_size, + &front_seg_size, NULL); } bbio = bio; } - if (nr_phys_segs == 1 && seg_size > fbio->bi_seg_front_size) - fbio->bi_seg_front_size = seg_size; + if (nr_phys_segs == 1 && seg_size > front_seg_size) + front_seg_size = seg_size; + fbio->bi_seg_front_size = front_seg_size; if (seg_size > bbio->bi_seg_back_size) bbio->bi_seg_back_size = seg_size; -- 2.9.5