From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id yMQ4Lk/IG1uvNQAAmS7hNA ; Sat, 09 Jun 2018 12:31:30 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id AE39F607BB; Sat, 9 Jun 2018 12:31:30 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=unavailable autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 328066032D; Sat, 9 Jun 2018 12:31:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 328066032D Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753365AbeFIMb2 (ORCPT + 25 others); Sat, 9 Jun 2018 08:31:28 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:44434 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753101AbeFIMb0 (ORCPT ); Sat, 9 Jun 2018 08:31:26 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1D8CC401EF22; Sat, 9 Jun 2018 12:31:26 +0000 (UTC) Received: from localhost (ovpn-12-40.pek2.redhat.com [10.72.12.40]) by smtp.corp.redhat.com (Postfix) with ESMTP id F38D42166BB2; Sat, 9 Jun 2018 12:31:17 +0000 (UTC) From: Ming Lei To: Jens Axboe , Christoph Hellwig , Alexander Viro , Kent Overstreet Cc: David Sterba , Huang Ying , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Theodore Ts'o , "Darrick J . Wong" , Coly Li , Filipe Manana , Randy Dunlap , Ming Lei Subject: [PATCH V6 04/30] block: introduce multipage page bvec helpers Date: Sat, 9 Jun 2018 20:29:48 +0800 Message-Id: <20180609123014.8861-5-ming.lei@redhat.com> In-Reply-To: <20180609123014.8861-1-ming.lei@redhat.com> References: <20180609123014.8861-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Sat, 09 Jun 2018 12:31:26 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Sat, 09 Jun 2018 12:31:26 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'ming.lei@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch introduces helpers of 'bvec_iter_chunk_*' for multipage bvec(chunk) support. The introduced interfaces treate one bvec as real multipage chunk, for example, .bv_len is the total length of the multipage chunk. The existed helpers of bvec_iter_* are interfaces for supporting current bvec iterator which is thought as singlepage only by drivers, fs, dm and etc. These helpers will build singlepage bvec in flight, so users of current bio/bvec iterator still can work well and needn't change even though we store real multipage chunk into bvec table. 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 fe7a22dd133b..52c90ea1a96a 100644 --- a/include/linux/bvec.h +++ b/include/linux/bvec.h @@ -23,6 +23,44 @@ #include #include #include +#include + +/* + * What is multipage bvecs(chunk)? + * + * - bvec stored in bio->bi_io_vec is always multipage(mp) style + * + * - bvec(struct bio_vec) represents one physically contiguous I/O + * buffer, now the buffer may include more than one pages since + * multipage(mp) bvec is supported, and all these pages represented + * by one bvec is physically contiguous. Before mp support, at most + * one page can be included in one bvec, we call it singlepage(sp) + * bvec. + * + * - .bv_page of th bvec represents the 1st page in the mp chunk + * + * - .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_all() will be changed to return singlepage + * 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) singlepage bvec is generated in flight by bvec + * helpers from the stored multipage bvec(chunk) + * + * - In case that some components(such as iov_iter) need to support + * multipage chunk, we introduce new helpers(bvec_iter_chunk_*) for + * them. + */ /* * was unsigned short, but we might as well be ready for > 64kB I/O pages @@ -52,16 +90,35 @@ struct bvec_iter { */ #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx]) -#define bvec_iter_page(bvec, iter) \ +#define bvec_iter_chunk_page(bvec, iter) \ (__bvec_iter_bvec((bvec), (iter))->bv_page) -#define bvec_iter_len(bvec, iter) \ +#define bvec_iter_chunk_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 bvec_iter_chunk_offset(bvec, iter) \ (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done) +#define bvec_iter_page_idx_in_seg(bvec, iter) \ + (bvec_iter_chunk_offset((bvec), (iter)) / PAGE_SIZE) + +/* + * of singlepage(sp) segment. + * + * This helpers will be implemented for building sp bvec in flight. + */ +#define bvec_iter_offset(bvec, iter) \ + (bvec_iter_chunk_offset((bvec), (iter)) % PAGE_SIZE) + +#define bvec_iter_len(bvec, iter) \ + min_t(unsigned, bvec_iter_chunk_len((bvec), (iter)), \ + (PAGE_SIZE - (bvec_iter_offset((bvec), (iter))))) + +#define bvec_iter_page(bvec, iter) \ + nth_page(bvec_iter_chunk_page((bvec), (iter)), \ + bvec_iter_page_idx_in_seg((bvec), (iter))) + #define bvec_iter_bvec(bvec, iter) \ ((struct bio_vec) { \ .bv_page = bvec_iter_page((bvec), (iter)), \ -- 2.9.5