From patchwork Tue Dec 27 15:55:56 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 9489455 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 D41C962AAD for ; Tue, 27 Dec 2016 16:04:25 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C5D79201BC for ; Tue, 27 Dec 2016 16:04:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B9F6525D99; Tue, 27 Dec 2016 16:04:25 +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=-6.3 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED, FREEMAIL_FROM, RCVD_IN_DNSWL_HI, RCVD_IN_SORBS_SPAM, 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 63093201BC for ; Tue, 27 Dec 2016 16:04:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755256AbcL0QAc (ORCPT ); Tue, 27 Dec 2016 11:00:32 -0500 Received: from mail-pg0-f66.google.com ([74.125.83.66]:33216 "EHLO mail-pg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752551AbcL0P7v (ORCPT ); Tue, 27 Dec 2016 10:59:51 -0500 Received: by mail-pg0-f66.google.com with SMTP id g1so12793861pgn.0; Tue, 27 Dec 2016 07:59:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=nbKomeyo/s276AhlwE1vcf8txDHqU7R2iHv6j4lhQKQ=; b=MZuS5lklvsEnDAXAvV4RMXjj4ITY4Yq1Bd0598Y8KEZLa/xBI7AN/f0zlHwod8WtmN p1qv4RLynnicj+GM443O0dzuDVAaEXeP/IwM8lK05lXZyfrSF/JvYSlcrwXN1WJGLGc7 vWjEyBIaBDnskCGL8sOr/do/ozMLneRi9XNff3XB1RYV1fvLjaSJQjLsnzpunvss83ks lsSU7TlHQ8Ch/pzUYmF/u9rNXCo96qzrQzX39lafZ+hsCISEuIiyJa5P51fGuvAinyUj Fhu1ueAGuz0Nvd9YgrW+R9YiKBw58H2BUK9V3glvtPi3H5OPBNFXqEZwYkCgad3BPoIT LLHg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=nbKomeyo/s276AhlwE1vcf8txDHqU7R2iHv6j4lhQKQ=; b=JjuCOi4gIg4c6frUTu1GdAwrx2KBLfcHNgQw/s2KF6ujAaJ2XKdnuQQ38gtivZ+VTy hSGmYf4I75oePwGUojl8hnHRyr0QjbxGR8bqtn+7EflHzgs86Ul+NJPoAybpV7FI3Odx F0nJEmaAXzdKoJsAVvieDmUsiuLRj5H9NvAiUoBvDy2WlYyJ0/6keOVBciRl6S4baVW9 OonoMC9HplnfR0kKBFolQZhDdMRs/AJH2yjKzF1u68X6KF6KapdcJRtXXJDE9TnOumfB ocRck/OZH1of6GIKfMltrmeRZXyV/OuVkYQA3bi0co4ObTAzqnjAqyLOcCvmCuvvVMY1 mAyw== X-Gm-Message-State: AIkVDXK9jQaP1GWwlmX/FmFBlFZvI8ZmS4DURbrclRRT1gNEiGHzI+R2yz9gF3vgzmdDHw== X-Received: by 10.98.198.207 with SMTP id x76mr29873028pfk.33.1482854354643; Tue, 27 Dec 2016 07:59:14 -0800 (PST) Received: from localhost ([45.35.47.137]) by smtp.gmail.com with ESMTPSA id t67sm90727632pfg.13.2016.12.27.07.59.12 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Dec 2016 07:59:13 -0800 (PST) From: Ming Lei To: Jens Axboe , linux-kernel@vger.kernel.org Cc: linux-block@vger.kernel.org, Christoph Hellwig , Ming Lei , Kent Overstreet , Shaohua Li , Guoqing Jiang , Zheng Liu , Mike Christie , Jiri Kosina , Eric Wheeler , Yijing Wang , 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 v1 07/54] bcache: comment on direct access to bvec table Date: Tue, 27 Dec 2016 23:55:56 +0800 Message-Id: <1482854250-13481-8-git-send-email-tom.leiming@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1482854250-13481-1-git-send-email-tom.leiming@gmail.com> References: <1482854250-13481-1-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 Acked-by: Coly Li --- 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 a43eedd5804d..fc35cfb4d0f1 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 3a19cbc8b230..607b022259dc 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -208,6 +208,7 @@ 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; @@ -1156,6 +1157,8 @@ static void register_bdev(struct cache_sb *sb, struct page *sb_page, dc->bdev->bd_holder = dc; bio_init(&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); @@ -1799,6 +1802,7 @@ 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); @@ -1854,6 +1858,8 @@ static int register_cache(struct cache_sb *sb, struct page *sb_page, ca->bdev->bd_holder = ca; bio_init(&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;