From patchwork Sat Oct 29 08:08:20 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 9403395 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id BBE9260587 for ; Sat, 29 Oct 2016 08:28:25 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A807B2A1E2 for ; Sat, 29 Oct 2016 08:28:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9C8752A1EC; Sat, 29 Oct 2016 08:28:25 +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=-6.8 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,FREEMAIL_FROM,RCVD_IN_DNSWL_HI,T_DKIM_INVALID 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 4FA982A1E2 for ; Sat, 29 Oct 2016 08:28:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753705AbcJ2IOE (ORCPT ); Sat, 29 Oct 2016 04:14:04 -0400 Received: from mail-pf0-f193.google.com ([209.85.192.193]:34504 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941635AbcJ2INd (ORCPT ); Sat, 29 Oct 2016 04:13:33 -0400 Received: by mail-pf0-f193.google.com with SMTP id u84so3377643pfj.1; Sat, 29 Oct 2016 01:13:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=j7T8SrIFDygE3cDyxoT3kNLLcHP8HE7kNiJVbC2G4vc=; b=H3u0eF9SNz1YY7qYnPu5T91V6rRXX7fbBEPiqYQWQvPcpunhHpLGN+kJu5xk4xkZ4m pEELt1wYVUeT75MWanPToFt2KEgpsTZQq41MSZXxIRpSIOkklfNqLZQQoavB0kJR5lzY ItJm37uTGMWg9wYScpeQ/11gIzRu5M3D2XEnE5naqI7hMTPSJMiizfU/BbE0w/KD2k6I JLZU86TNkVu3Gl76b1rQL9iySKUyqZ3QeXPuUy+5U8Zij6qbnu2mhfHPVY117ADeZFVP TaFQz2QQid3w1/jtZ6lR1DqvF53+OEFUY7kTUQn4A7iMbSHarXCGMq98DQPkd+1Ml5Di SNIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=j7T8SrIFDygE3cDyxoT3kNLLcHP8HE7kNiJVbC2G4vc=; b=GE/dj3DQkH808QWix/RK2Hl1BM/+ZfYTNjhk2UgOtPxc/WJScuApyZ1pykqQl8lnJD S9TBSQjXMuCHb05IFqz8NLINqAaur8YQX1y1bmFT7WitpxXuNXR06dMUMZ0SiJasI2Vp Q4kIRmKXr2JDnYLSoFgY7PeiK+uBxZMdGXUtWeMJNXQuLabJasv3avygmuZRJpdpC1Lj Ib2PKIE18TU4QzVI82MXUFWsAI3vLjZ7gD4ZuNgWayyiGe7YTT4DvgV2kpXboSsVCgZN PKYCShEQLI0Sxlg0/UPtq+D1jIsRD0ZODcXL5jUESw4KBc9GwC2txqqAjWUoGleuDFGS f+mQ== X-Gm-Message-State: ABUngvej5gRo9qKuiVmHun3uyME72g7BpJ7eKUo8AARoYsWSi6VOWIbJEFM0PlUyezqvOA== X-Received: by 10.99.230.17 with SMTP id g17mr25990552pgh.82.1477728811842; Sat, 29 Oct 2016 01:13:31 -0700 (PDT) Received: from localhost ([45.34.23.101]) by smtp.gmail.com with ESMTPSA id v10sm23538390pag.44.2016.10.29.01.13.30 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 29 Oct 2016 01:13:31 -0700 (PDT) From: Ming Lei To: Jens Axboe , linux-kernel@vger.kernel.org Cc: linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, Christoph Hellwig , "Kirill A . Shutemov" , Ming Lei , Kent Overstreet , Shaohua Li , Mike Christie , Hannes Reinecke , Guoqing Jiang , Jiri Kosina , Zheng Liu , Eric Wheeler , Yijing Wang , Coly Li , Al Viro , linux-bcache@vger.kernel.org (open list:BCACHE (BLOCK LAYER CACHE)), linux-raid@vger.kernel.org (open list:SOFTWARE RAID (Multiple Disks) SUPPORT) Subject: [PATCH 21/60] bcache: comment on direct access to bvec table Date: Sat, 29 Oct 2016 16:08:20 +0800 Message-Id: <1477728600-12938-22-git-send-email-tom.leiming@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1477728600-12938-1-git-send-email-tom.leiming@gmail.com> References: <1477728600-12938-1-git-send-email-tom.leiming@gmail.com> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Looks all are safe after multipage bvec is supported. Signed-off-by: Ming Lei --- drivers/md/bcache/btree.c | 1 + drivers/md/bcache/super.c | 6 ++++++ drivers/md/bcache/util.c | 7 +++++++ 3 files changed, 14 insertions(+) diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c index 81d3db40cd7b..b419bc91ba32 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -428,6 +428,7 @@ static void do_btree_node_write(struct btree *b) continue_at(cl, btree_node_write_done, NULL); } else { + /* No harm for multipage bvec since the new is just allocated */ b->bio->bi_vcnt = 0; bch_bio_map(b->bio, i); diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index d8a6d807b498..52876fcf2b36 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -207,6 +207,7 @@ static void write_bdev_super_endio(struct bio *bio) static void __write_super(struct cache_sb *sb, struct bio *bio) { + /* single page bio, safe for multipage bvec */ struct cache_sb *out = page_address(bio->bi_io_vec[0].bv_page); unsigned i; @@ -1153,6 +1154,8 @@ static void register_bdev(struct cache_sb *sb, struct page *sb_page, dc->bdev->bd_holder = dc; bio_init_with_vec_table(&dc->sb_bio, dc->sb_bio.bi_inline_vecs, 1); + + /* single page bio, safe for multipage bvec */ dc->sb_bio.bi_io_vec[0].bv_page = sb_page; get_page(sb_page); @@ -1794,6 +1797,7 @@ void bch_cache_release(struct kobject *kobj) for (i = 0; i < RESERVE_NR; i++) free_fifo(&ca->free[i]); + /* single page bio, safe for multipage bvec */ if (ca->sb_bio.bi_inline_vecs[0].bv_page) put_page(ca->sb_bio.bi_io_vec[0].bv_page); @@ -1850,6 +1854,8 @@ static int register_cache(struct cache_sb *sb, struct page *sb_page, ca->bdev->bd_holder = ca; bio_init_with_vec_table(&ca->sb_bio, ca->sb_bio.bi_inline_vecs, 1); + + /* single page bio, safe for multipage bvec */ ca->sb_bio.bi_io_vec[0].bv_page = sb_page; get_page(sb_page); diff --git a/drivers/md/bcache/util.c b/drivers/md/bcache/util.c index dde6172f3f10..5cc0b49a65fb 100644 --- a/drivers/md/bcache/util.c +++ b/drivers/md/bcache/util.c @@ -222,6 +222,13 @@ uint64_t bch_next_delay(struct bch_ratelimit *d, uint64_t done) : 0; } +/* + * Generally it isn't good to access .bi_io_vec and .bi_vcnt + * directly, the preferred way is bio_add_page, but in + * this case, bch_bio_map() supposes that the bvec table + * is empty, so it is safe to access .bi_vcnt & .bi_io_vec + * in this way even after multipage bvec is supported. + */ void bch_bio_map(struct bio *bio, void *base) { size_t size = bio->bi_iter.bi_size;