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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 83A8DC43441 for ; Fri, 16 Nov 2018 13:58:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5656B2086C for ; Fri, 16 Nov 2018 13:58:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5656B2086C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de 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 S2389829AbeKQAKh (ORCPT ); Fri, 16 Nov 2018 19:10:37 -0500 Received: from verein.lst.de ([213.95.11.211]:50112 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727854AbeKQAKh (ORCPT ); Fri, 16 Nov 2018 19:10:37 -0500 Received: by newverein.lst.de (Postfix, from userid 2407) id EF8E968D60; Fri, 16 Nov 2018 14:58:03 +0100 (CET) Date: Fri, 16 Nov 2018 14:58:03 +0100 From: Christoph Hellwig To: Ming Lei Cc: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Kent Overstreet , Mike Snitzer , dm-devel@redhat.com, Alexander Viro , linux-fsdevel@vger.kernel.org, Shaohua Li , linux-raid@vger.kernel.org, linux-erofs@lists.ozlabs.org, David Sterba , linux-btrfs@vger.kernel.org, "Darrick J . Wong" , linux-xfs@vger.kernel.org, Gao Xiang , Christoph Hellwig , Theodore Ts'o , linux-ext4@vger.kernel.org, Coly Li , linux-bcache@vger.kernel.org, Boaz Harrosh , Bob Peterson , cluster-devel@redhat.com Subject: Re: [PATCH V10 18/19] block: kill QUEUE_FLAG_NO_SG_MERGE Message-ID: <20181116135803.GN3165@lst.de> References: <20181115085306.9910-1-ming.lei@redhat.com> <20181115085306.9910-19-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181115085306.9910-19-ming.lei@redhat.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 15, 2018 at 04:53:05PM +0800, Ming Lei wrote: > Since bdced438acd83ad83a6c ("block: setup bi_phys_segments after splitting"), > physical segment number is mainly figured out in blk_queue_split() for > fast path, and the flag of BIO_SEG_VALID is set there too. > > Now only blk_recount_segments() and blk_recalc_rq_segments() use this > flag. > > Basically blk_recount_segments() is bypassed in fast path given BIO_SEG_VALID > is set in blk_queue_split(). > > For another user of blk_recalc_rq_segments(): > > - run in partial completion branch of blk_update_request, which is an unusual case > > - run in blk_cloned_rq_check_limits(), still not a big problem if the flag is killed > since dm-rq is the only user. > > Multi-page bvec is enabled now, QUEUE_FLAG_NO_SG_MERGE doesn't make sense any more. > > Cc: Dave Chinner > Cc: Kent Overstreet > Cc: Mike Snitzer > Cc: dm-devel@redhat.com > Cc: Alexander Viro > Cc: linux-fsdevel@vger.kernel.org > Cc: Shaohua Li > Cc: linux-raid@vger.kernel.org > Cc: linux-erofs@lists.ozlabs.org > Cc: David Sterba > Cc: linux-btrfs@vger.kernel.org > Cc: Darrick J. Wong > Cc: linux-xfs@vger.kernel.org > Cc: Gao Xiang > Cc: Christoph Hellwig > Cc: Theodore Ts'o > Cc: linux-ext4@vger.kernel.org > Cc: Coly Li > Cc: linux-bcache@vger.kernel.org > Cc: Boaz Harrosh > Cc: Bob Peterson > Cc: cluster-devel@redhat.com > Signed-off-by: Ming Lei > --- > block/blk-merge.c | 31 ++++++------------------------- > block/blk-mq-debugfs.c | 1 - > block/blk-mq.c | 3 --- > drivers/md/dm-table.c | 13 ------------- > include/linux/blkdev.h | 1 - > 5 files changed, 6 insertions(+), 43 deletions(-) > > diff --git a/block/blk-merge.c b/block/blk-merge.c > index 153a659fde74..06be298be332 100644 > --- a/block/blk-merge.c > +++ b/block/blk-merge.c > @@ -351,8 +351,7 @@ void blk_queue_split(struct request_queue *q, struct bio **bio) > EXPORT_SYMBOL(blk_queue_split); > > static unsigned int __blk_recalc_rq_segments(struct request_queue *q, > - struct bio *bio, > - bool no_sg_merge) > + struct bio *bio) > { > struct bio_vec bv, bvprv = { NULL }; > int cluster, prev = 0; > @@ -379,13 +378,6 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, > nr_phys_segs = 0; > for_each_bio(bio) { > bio_for_each_bvec(bv, bio, iter) { > - /* > - * If SG merging is disabled, each bio vector is > - * a segment > - */ > - if (no_sg_merge) > - goto new_segment; > - > if (prev && cluster) { > if (seg_size + bv.bv_len > > queue_max_segment_size(q)) > @@ -420,27 +412,16 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, > > void blk_recalc_rq_segments(struct request *rq) > { > - bool no_sg_merge = !!test_bit(QUEUE_FLAG_NO_SG_MERGE, > - &rq->q->queue_flags); > - > - rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio, > - no_sg_merge); > + rq->nr_phys_segments = __blk_recalc_rq_segments(rq->q, rq->bio); Can we rename __blk_recalc_rq_segments to blk_recalc_rq_segments can kill the old blk_recalc_rq_segments now? Otherwise looks fine: Reviewed-by: Christoph Hellwig