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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 4A465C43603 for ; Wed, 23 Dec 2020 02:56:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 154F4205CA for ; Wed, 23 Dec 2020 02:56:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730934AbgLWC43 (ORCPT ); Tue, 22 Dec 2020 21:56:29 -0500 Received: from mail.kernel.org ([198.145.29.99]:49658 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729130AbgLWCUz (ORCPT ); Tue, 22 Dec 2020 21:20:55 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7C793229CA; Wed, 23 Dec 2020 02:20:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1608690014; bh=y3xnCdMjaalb1+NugOTJYOLDazlf9ZWnnOZtAxErUFA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rd8m5iXPXeN9I4gwE+Eu3ekGn753SeGoUjn9JUY+HS3f4Oe1JJAvdaU6VtSQE5+t0 YmB7jvpYNnWx5e1FWxDiCiLheGk41UZJIHeDjLHqibzkkBMth3gupfOKNbG+SATTU6 yHua82QgCRh5b2bVdNdUGhLihvk9rs6mV+HlRSUiIL6VA49gmw1aAxI4NEA6fgg8aE 3mXGI5tBti+Jz5t/cPejabRbNPQbdaoIV6mUJet+k57/6rnfs08Pdu7IuiiHJ5pAAb vca76KOvkPhDopah/nM+nOuhnYyOyUO3GXqYIMe0m9IfhqtqlxqgWvRC9KO8zvxmII pUyrZI7uirwxg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Dongsheng Yang , Coly Li , Jens Axboe , Sasha Levin , linux-bcache@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 093/130] bcache: fix race between setting bdev state to none and new write request direct to backing Date: Tue, 22 Dec 2020 21:17:36 -0500 Message-Id: <20201223021813.2791612-93-sashal@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20201223021813.2791612-1-sashal@kernel.org> References: <20201223021813.2791612-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dongsheng Yang [ Upstream commit df4ad53242158f9f1f97daf4feddbb4f8b77f080 ] There is a race condition in detaching as below: A. detaching B. Write request (1) writing back (2) write back done, set bdev state to clean. (3) cached_dev_put() and schedule_work(&dc->detach); (4) write data [0 - 4K] directly into backing and ack to user. (5) power-failure... When we restart this bcache device, this bdev is clean but not detached, and read [0 - 4K], we will get unexpected old data from cache device. To fix this problem, set the bdev state to none when we writeback done in detaching, and then if power-failure happened as above, the data in cache will not be used in next bcache device starting, it's detached, we will read the correct data from backing derectly. Signed-off-by: Dongsheng Yang Signed-off-by: Coly Li Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/md/bcache/super.c | 9 --------- drivers/md/bcache/writeback.c | 9 +++++++++ 2 files changed, 9 insertions(+), 9 deletions(-) diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index 63f5ce18311bb..a251c1f35afa9 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -1040,9 +1040,6 @@ static void cancel_writeback_rate_update_dwork(struct cached_dev *dc) static void cached_dev_detach_finish(struct work_struct *w) { struct cached_dev *dc = container_of(w, struct cached_dev, detach); - struct closure cl; - - closure_init_stack(&cl); BUG_ON(!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)); BUG_ON(refcount_read(&dc->count)); @@ -1056,12 +1053,6 @@ static void cached_dev_detach_finish(struct work_struct *w) dc->writeback_thread = NULL; } - memset(&dc->sb.set_uuid, 0, 16); - SET_BDEV_STATE(&dc->sb, BDEV_STATE_NONE); - - bch_write_bdev_super(dc, &cl); - closure_sync(&cl); - mutex_lock(&bch_register_lock); calc_cached_dev_sectors(dc->disk.c); diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index 0b02210ab4355..38b5c6cc18c7b 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -703,6 +703,15 @@ static int bch_writeback_thread(void *arg) * bch_cached_dev_detach(). */ if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)) { + struct closure cl; + + closure_init_stack(&cl); + memset(&dc->sb.set_uuid, 0, 16); + SET_BDEV_STATE(&dc->sb, BDEV_STATE_NONE); + + bch_write_bdev_super(dc, &cl); + closure_sync(&cl); + up_write(&dc->writeback_lock); break; } -- 2.27.0