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,URIBL_BLOCKED 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 6BE0BC43441 for ; Tue, 13 Nov 2018 15:15:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3EC912251B for ; Tue, 13 Nov 2018 15:15:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3EC912251B 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-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732767AbeKNBOC (ORCPT ); Tue, 13 Nov 2018 20:14:02 -0500 Received: from mx1.redhat.com ([209.132.183.28]:38873 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730765AbeKNBOB (ORCPT ); Tue, 13 Nov 2018 20:14:01 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BE8848046B; Tue, 13 Nov 2018 15:15:27 +0000 (UTC) Received: from localhost (ovpn-8-23.pek2.redhat.com [10.72.8.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id BF1175D9C8; Tue, 13 Nov 2018 15:15:23 +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 V9 01/19] block: introduce multi-page page bvec helpers Date: Tue, 13 Nov 2018 23:14:47 +0800 Message-Id: <20181113151505.15498-2-ming.lei@redhat.com> In-Reply-To: <20181113151505.15498-1-ming.lei@redhat.com> References: <20181113151505.15498-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Tue, 13 Nov 2018 15:15:27 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org This patch introduces helpers of 'mp_bvec_iter_*' for multipage bvec support. The introduced helpers treate one bvec as real multi-page segment, which may include more than one pages. The existed helpers of bvec_iter_* are interfaces for supporting current bvec iterator which is thought as single-page by drivers, fs, dm and etc. These introduced helpers will build single-page bvec in flight, so this way won't break current bio/bvec users, which needn't any change. Cc: Christoph Hellwig Signed-off-by: Ming Lei --- include/linux/bvec.h | 63 +++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 60 insertions(+), 3 deletions(-) diff --git a/include/linux/bvec.h b/include/linux/bvec.h index 02c73c6aa805..8ef904a50577 100644 --- a/include/linux/bvec.h +++ b/include/linux/bvec.h @@ -23,6 +23,44 @@ #include #include #include +#include + +/* + * What is multi-page bvecs? + * + * - bvecs stored in bio->bi_io_vec is always multi-page(mp) style + * + * - bvec(struct bio_vec) represents one physically contiguous I/O + * buffer, now the buffer may include more than one pages after + * multi-page(mp) bvec is supported, and all these pages represented + * by one bvec is physically contiguous. Before mp support, at most + * one page is included in one bvec, we call it single-page(sp) + * bvec. + * + * - .bv_page of the bvec represents the 1st page in the mp bvec + * + * - .bv_offset of the bvec represents offset of the buffer in the bvec + * + * The effect on the current drivers/filesystem/dm/bcache/...: + * + * - almost everyone supposes that one bvec only includes one single + * page, so we keep the sp interface not changed, for example, + * bio_for_each_segment() still returns bvec with single page + * + * - bio_for_each_segment*() will be changed to return single-page + * bvec too + * + * - during iterating, iterator variable(struct bvec_iter) is always + * updated in multipage bvec style and that means bvec_iter_advance() + * is kept not changed + * + * - returned(copied) single-page bvec is built in flight by bvec + * helpers from the stored multipage bvec + * + * - In case that some components(such as iov_iter) need to support + * multi-page bvec, we introduce new helpers(mp_bvec_iter_*) for + * them. + */ /* * was unsigned short, but we might as well be ready for > 64kB I/O pages @@ -50,16 +88,35 @@ struct bvec_iter { */ #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx]) -#define bvec_iter_page(bvec, iter) \ +#define mp_bvec_iter_page(bvec, iter) \ (__bvec_iter_bvec((bvec), (iter))->bv_page) -#define bvec_iter_len(bvec, iter) \ +#define mp_bvec_iter_len(bvec, iter) \ min((iter).bi_size, \ __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done) -#define bvec_iter_offset(bvec, iter) \ +#define mp_bvec_iter_offset(bvec, iter) \ (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done) +#define mp_bvec_iter_page_idx(bvec, iter) \ + (mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE) + +/* + * of single-page(sp) segment. + * + * This helpers are for building sp bvec in flight. + */ +#define bvec_iter_offset(bvec, iter) \ + (mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE) + +#define bvec_iter_len(bvec, iter) \ + min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \ + (PAGE_SIZE - (bvec_iter_offset((bvec), (iter))))) + +#define bvec_iter_page(bvec, iter) \ + nth_page(mp_bvec_iter_page((bvec), (iter)), \ + mp_bvec_iter_page_idx((bvec), (iter))) + #define bvec_iter_bvec(bvec, iter) \ ((struct bio_vec) { \ .bv_page = bvec_iter_page((bvec), (iter)), \ -- 2.9.5