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=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable 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 70590C43441 for ; Mon, 26 Nov 2018 22:14:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 312692082F for ; Mon, 26 Nov 2018 22:14:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=osandov-com.20150623.gappssmtp.com header.i=@osandov-com.20150623.gappssmtp.com header.b="O7WNWIgz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 312692082F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=osandov.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-btrfs-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726914AbeK0JKZ (ORCPT ); Tue, 27 Nov 2018 04:10:25 -0500 Received: from mail-pf1-f195.google.com ([209.85.210.195]:32770 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727076AbeK0JKY (ORCPT ); Tue, 27 Nov 2018 04:10:24 -0500 Received: by mail-pf1-f195.google.com with SMTP id c123so6569867pfb.0 for ; Mon, 26 Nov 2018 14:14:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=osandov-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=9AkyZOjm/sng5co17bYs/2llMKYYVqfTbY1b6HL7DLY=; b=O7WNWIgzkXf1oK/nBoaA7B4ovU42gjQqCbUt0jqoaewwuXODvM+n28sAcfrqBN9FxF d+sCGTNY8vm9rg4JinMqrXUuXNXRMlbt1mxB1YKPSUhT4JVM7iS2IlpdA4gQ0Dbtly6B b2f7hLoWHcdQSAZNx+KRZWuj5zakI4I7SM2Qr/3tFvtVY8TpnkvNwPHrG5yJ9VGMFgtr yYMsTmf2CRSl8Pu6UI0/a3xitEaMyrgsc53AbOgHEJwUU8vUMnbYjVGEPT07Pl1LiopT aO9PKUVWDb+36q4jj+nyvSoOvdeWUlrWvviQvDDHOl9BFLYcvbShWR4hYnL9ThOjXc6n J73Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=9AkyZOjm/sng5co17bYs/2llMKYYVqfTbY1b6HL7DLY=; b=HowTTBxXpeWb5AOL+OJrhsHngbGc3FA5eXqSiTKRy1Z2C0lwNwuCIhanYvkaoWoed4 zixf1rEFCj1QXn7facyEiXMCNSAeTHgjeAULQZMayI+922brihypxIQgUBL/YlAkHJIb UMJhF91/IpEZJzAz8ug284FFy0etS6ArNG7fV94PylceVoC5SIFkf2zUa1dKApI0q3VF Uc6LipZyR3d099sgQiZhVhzu/r4aGYnr3hBUF5BzW66m78vW7+lV4zWqqaXKA2fA21Q5 F/jqUOiq3kC/2aP42afkjJzBkE0hNdG9b++RL74OsSxlyUcyYIglzkMuDQVLdmXOQ0qd yPIw== X-Gm-Message-State: AA+aEWb+kuJUIU7a8R+uGCEtL+qYMnso1oQuBe2UnS1grMjIYhJhPKmg 7DYcXhbu3UohvPotL7YoqwwX0w== X-Google-Smtp-Source: AFSGD/Vm+Spxe/zyUiRC0YAVLq9Jbt6VMBjbU7UkRQ356r0R43oVMqtcBLFDj2BhbKX//LTFiFkUvQ== X-Received: by 2002:a63:78cd:: with SMTP id t196mr26824599pgc.62.1543270489280; Mon, 26 Nov 2018 14:14:49 -0800 (PST) Received: from vader ([2601:602:8b00:55d3:e6a7:a0ff:fe0b:c9a8]) by smtp.gmail.com with ESMTPSA id c67sm1688753pfg.170.2018.11.26.14.14.48 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 26 Nov 2018 14:14:48 -0800 (PST) Date: Mon, 26 Nov 2018 14:14:47 -0800 From: Omar Sandoval To: Ming Lei Cc: Jens Axboe , 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, Shaohua Li , 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 Subject: Re: [PATCH V12 04/20] block: don't use bio->bi_vcnt to figure out segment number Message-ID: <20181126221447.GE30411@vader> References: <20181126021720.19471-1-ming.lei@redhat.com> <20181126021720.19471-5-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181126021720.19471-5-ming.lei@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Mon, Nov 26, 2018 at 10:17:04AM +0800, Ming Lei wrote: > It is wrong to use bio->bi_vcnt to figure out how many segments > there are in the bio even though CLONED flag isn't set on this bio, > because this bio may be splitted or advanced. > > So always use bio_segments() in blk_recount_segments(), and it shouldn't > cause any performance loss now because the physical segment number is figured > out in blk_queue_split() and BIO_SEG_VALID is set meantime since > bdced438acd83ad83a6c ("block: setup bi_phys_segments after splitting"). > > Reviewed-by: Christoph Hellwig Reviewed-by: Omar Sandoval > Fixes: 76d8137a3113 ("blk-merge: recaculate segment if it isn't less than max segments") > Signed-off-by: Ming Lei > --- > block/blk-merge.c | 8 +------- > 1 file changed, 1 insertion(+), 7 deletions(-) > > diff --git a/block/blk-merge.c b/block/blk-merge.c > index e69d8f8ba819..51ec6ca56a0a 100644 > --- a/block/blk-merge.c > +++ b/block/blk-merge.c > @@ -367,13 +367,7 @@ void blk_recalc_rq_segments(struct request *rq) > > void blk_recount_segments(struct request_queue *q, struct bio *bio) > { > - unsigned short seg_cnt; > - > - /* estimate segment number by bi_vcnt for non-cloned bio */ > - if (bio_flagged(bio, BIO_CLONED)) > - seg_cnt = bio_segments(bio); > - else > - seg_cnt = bio->bi_vcnt; > + unsigned short seg_cnt = bio_segments(bio); > > if (test_bit(QUEUE_FLAG_NO_SG_MERGE, &q->queue_flags) && > (seg_cnt < queue_max_segments(q))) > -- > 2.9.5 >