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=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 418C3C43441 for ; Mon, 26 Nov 2018 22:39:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EDA1220873 for ; Mon, 26 Nov 2018 22:39:43 +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="kWu3M/Pg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EDA1220873 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 S1727412AbeK0JfV (ORCPT ); Tue, 27 Nov 2018 04:35:21 -0500 Received: from mail-pg1-f194.google.com ([209.85.215.194]:35163 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727066AbeK0JfU (ORCPT ); Tue, 27 Nov 2018 04:35:20 -0500 Received: by mail-pg1-f194.google.com with SMTP id s198so6851890pgs.2 for ; Mon, 26 Nov 2018 14:39:41 -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=RUaiQARROohQiAOdny5us6dTb3HLIuGpGt6crRAlRs8=; b=kWu3M/Pg7YRitikkahpKiBl5cCUnoiBMDo/k7D4nxQKGNeUrhzsp3IHHN3doNwb/kD e+9EBrzpQwB1ZBTyEn44PpIKLid6y29HqBgkdjvAB+Bg1igpAKj3RVm/PKOxRyqGPY2T X1rggbUOJC5rYhwhHSW/Hh59KSJuPHtxnoOYRn7BqHzxEdVNZLywgqCv6o62Cd/XzV6n PeAdxxPpGLw9a7YBjD1adzo7n6tgd5+FvwuuKMouy46sgY8NzvhWen76DwmWnzzNYePH acjs1KTVl6/uL/knjosfu1aMoXstmrlISal/OL9bYMv4RMuinjL5cWOJWhT0eMGeDgNx vt+Q== 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=RUaiQARROohQiAOdny5us6dTb3HLIuGpGt6crRAlRs8=; b=s7zOo1cWaSzeGM3Isw4VPyWzu/vIEc2AU8HHDQAQP6JrAp8GNgfH1v97ot94CNevIh 30xQacyElECQZ9LZQ7iyDPuPF8JU9h1f4lbQKyRgvOlEoZLx+CCALWhGtwoliDDeRaiE HAQXcrsgz4nXsNpr0URcNG2/3/QE33HIMyyzvQj65EkK7U5tGMHh08qBq3LoF310C7h/ bqDtxZC2NE36bShkS6fFfD8f8SbrIKb0IBTbpwab/ttj66pHi/za5yCY6ZP3gVi2cG0g UPF0RAt/C++w/MP+R+coYx5ZJbebM8JWMew9N3GGhCP8T9hp5DMgnw+tvL71nmkqqaDy TvIQ== X-Gm-Message-State: AA+aEWbCAKLVDuP/E2MsJiwNlIkelgaPKQ8rdZSyj9RWZzCQuHF+h6BS T6sd1RKOYONr7fT5mths7Pf5vg== X-Google-Smtp-Source: AFSGD/WKF2YX6sjXdtrywlIZWIhARgrTQBAsfQcHBfGoFipMevteRNDHtxwiJzMkTPu20TTEPw3acw== X-Received: by 2002:a62:4b4d:: with SMTP id y74mr28649197pfa.186.1543271980701; Mon, 26 Nov 2018 14:39:40 -0800 (PST) Received: from vader ([2601:602:8b00:55d3:e6a7:a0ff:fe0b:c9a8]) by smtp.gmail.com with ESMTPSA id y12sm2059602pfk.70.2018.11.26.14.39.39 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 26 Nov 2018 14:39:40 -0800 (PST) Date: Mon, 26 Nov 2018 14:39:38 -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 13/20] block: loop: pass multi-page bvec to iov_iter Message-ID: <20181126223938.GJ30411@vader> References: <20181126021720.19471-1-ming.lei@redhat.com> <20181126021720.19471-14-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181126021720.19471-14-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 10:17:13AM +0800, Ming Lei wrote: > iov_iter is implemented on bvec itererator helpers, so it is safe to pass > multi-page bvec to it, and this way is much more efficient than passing one > page in each bvec. > > Reviewed-by: Christoph Hellwig Reviewed-by: Omar Sandoval > Signed-off-by: Ming Lei > --- > drivers/block/loop.c | 20 ++++++++++---------- > 1 file changed, 10 insertions(+), 10 deletions(-) > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index 176ab1f28eca..e3683211f12d 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -510,21 +510,22 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, > loff_t pos, bool rw) > { > struct iov_iter iter; > + struct req_iterator rq_iter; > struct bio_vec *bvec; > struct request *rq = blk_mq_rq_from_pdu(cmd); > struct bio *bio = rq->bio; > struct file *file = lo->lo_backing_file; > + struct bio_vec tmp; > unsigned int offset; > - int segments = 0; > + int nr_bvec = 0; > int ret; > > + rq_for_each_bvec(tmp, rq, rq_iter) > + nr_bvec++; > + > if (rq->bio != rq->biotail) { > - struct req_iterator iter; > - struct bio_vec tmp; > > - __rq_for_each_bio(bio, rq) > - segments += bio_segments(bio); > - bvec = kmalloc_array(segments, sizeof(struct bio_vec), > + bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec), > GFP_NOIO); > if (!bvec) > return -EIO; > @@ -533,10 +534,10 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, > /* > * The bios of the request may be started from the middle of > * the 'bvec' because of bio splitting, so we can't directly > - * copy bio->bi_iov_vec to new bvec. The rq_for_each_segment > + * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec > * API will take care of all details for us. > */ > - rq_for_each_segment(tmp, rq, iter) { > + rq_for_each_bvec(tmp, rq, rq_iter) { > *bvec = tmp; > bvec++; > } > @@ -550,11 +551,10 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, > */ > offset = bio->bi_iter.bi_bvec_done; > bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); > - segments = bio_segments(bio); > } > atomic_set(&cmd->ref, 2); > > - iov_iter_bvec(&iter, rw, bvec, segments, blk_rq_bytes(rq)); > + iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq)); > iter.iov_offset = offset; > > cmd->iocb.ki_pos = pos; > -- > 2.9.5 >