From patchwork Wed Nov 21 03:23:10 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 10691613 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 14B8016B1 for ; Wed, 21 Nov 2018 03:25:26 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 047432B406 for ; Wed, 21 Nov 2018 03:25:26 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id ECAB42B412; Wed, 21 Nov 2018 03:25:25 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 905B52B406 for ; Wed, 21 Nov 2018 03:25:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727360AbeKUN5s (ORCPT ); Wed, 21 Nov 2018 08:57:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37582 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726165AbeKUN5s (ORCPT ); Wed, 21 Nov 2018 08:57:48 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E04BD81DE1; Wed, 21 Nov 2018 03:25:16 +0000 (UTC) Received: from localhost (ovpn-8-21.pek2.redhat.com [10.72.8.21]) by smtp.corp.redhat.com (Postfix) with ESMTP id AFB61BABB; Wed, 21 Nov 2018 03:25:02 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: 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, Ming Lei Subject: [PATCH V11 02/19] block: introduce multi-page bvec helpers Date: Wed, 21 Nov 2018 11:23:10 +0800 Message-Id: <20181121032327.8434-3-ming.lei@redhat.com> In-Reply-To: <20181121032327.8434-1-ming.lei@redhat.com> References: <20181121032327.8434-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Wed, 21 Nov 2018 03:25:17 +0000 (UTC) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This patch introduces helpers of 'segment_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. Follows some multi-page bvec background: - bvecs stored in bio->bi_io_vec is always multi-page style - bvec(struct bio_vec) represents one physically contiguous I/O buffer, now the buffer may include more than one page after multi-page bvec is supported, and all these pages represented by one bvec is physically contiguous. Before multi-page bvec support, at most one page is included in one bvec, we call it single-page bvec. - .bv_page of the bvec points to the 1st page in the multi-page bvec - .bv_offset of the bvec is the 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 single-page bvec - bio_for_each_segment_all() will return single-page bvec too - during iterating, iterator variable(struct bvec_iter) is always updated in multi-page bvec style, and bvec_iter_advance() is kept not changed - returned(copied) single-page bvec is built in flight by bvec helpers from the stored multi-page bvec Reviewed-by: Omar Sandoval Signed-off-by: Ming Lei --- include/linux/bvec.h | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/include/linux/bvec.h b/include/linux/bvec.h index 02c73c6aa805..ed90bbf4c9c9 100644 --- a/include/linux/bvec.h +++ b/include/linux/bvec.h @@ -23,6 +23,7 @@ #include #include #include +#include /* * was unsigned short, but we might as well be ready for > 64kB I/O pages @@ -50,16 +51,35 @@ struct bvec_iter { */ #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx]) -#define bvec_iter_page(bvec, iter) \ +#define segment_iter_page(bvec, iter) \ (__bvec_iter_bvec((bvec), (iter))->bv_page) -#define bvec_iter_len(bvec, iter) \ +#define segment_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 segment_iter_offset(bvec, iter) \ (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done) +#define segment_iter_page_idx(bvec, iter) \ + (segment_iter_offset((bvec), (iter)) / PAGE_SIZE) + +/* + * of single-page segment. + * + * This helpers are for building single-page bvec in flight. + */ +#define bvec_iter_offset(bvec, iter) \ + (segment_iter_offset((bvec), (iter)) % PAGE_SIZE) + +#define bvec_iter_len(bvec, iter) \ + min_t(unsigned, segment_iter_len((bvec), (iter)), \ + PAGE_SIZE - bvec_iter_offset((bvec), (iter))) + +#define bvec_iter_page(bvec, iter) \ + nth_page(segment_iter_page((bvec), (iter)), \ + segment_iter_page_idx((bvec), (iter))) + #define bvec_iter_bvec(bvec, iter) \ ((struct bio_vec) { \ .bv_page = bvec_iter_page((bvec), (iter)), \