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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 14C66C432C3 for ; Tue, 3 Dec 2019 23:06:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C643420656 for ; Tue, 3 Dec 2019 23:06:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575414370; bh=MqCGkEaFKEvYpnpR5yjcDLhn3RcaqfJeMd3Ts7sMgNM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ezvf/2JbPody12T1wWoZX28dFbh4DAsO8GmHUELJ92V22WXKervdlr1UikinGhzQL nFgu6+3mPBeh3Sus8DZvgxcR8h2cJIJFFOlpEVDEyep269/bpZd+92pW0lOID9hnvg Zt6EtYxMMJnD/7fRrEdh3Iq+d6Y8MzeeckoyF0Bo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729567AbfLCWtQ (ORCPT ); Tue, 3 Dec 2019 17:49:16 -0500 Received: from mail.kernel.org ([198.145.29.99]:40152 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729559AbfLCWtN (ORCPT ); Tue, 3 Dec 2019 17:49:13 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 55A8220684; Tue, 3 Dec 2019 22:49:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575413352; bh=MqCGkEaFKEvYpnpR5yjcDLhn3RcaqfJeMd3Ts7sMgNM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HxF9BIy//Iq/yRrjqSJg9rilW0keTxlqt28wVaC9z7g69Bfl9LD1gAgqZCz0DjjTb Wd/GKkPpVxTZ9n6SG1nBy1NkosE9QB/6rdoO9cIUtJ1ZjRCDXW6PWAXCElTHLqV0rO KvSIgEDLjJDIUnNw6Z1pTV6zQF/CZv3EMYF0lufA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Shenghui Wang , Coly Li , Jens Axboe , Sasha Levin Subject: [PATCH 4.19 096/321] bcache: do not mark writeback_running too early Date: Tue, 3 Dec 2019 23:32:42 +0100 Message-Id: <20191203223432.153600792@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191203223427.103571230@linuxfoundation.org> References: <20191203223427.103571230@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Shenghui Wang [ Upstream commit 79b791466e525c98f6aeee9acf5726e7b27f4231 ] A fresh backing device is not attached to any cache_set, and has no writeback kthread created until first attached to some cache_set. But bch_cached_dev_writeback_init run " dc->writeback_running = true; WARN_ON(test_and_clear_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags)); " for any newly formatted backing devices. For a fresh standalone backing device, we can get something like following even if no writeback kthread created: ------------------------ /sys/block/bcache0/bcache# cat writeback_running 1 /sys/block/bcache0/bcache# cat writeback_rate_debug rate: 512.0k/sec dirty: 0.0k target: 0.0k proportional: 0.0k integral: 0.0k change: 0.0k/sec next io: -15427384ms The none ZERO fields are misleading as no alive writeback kthread yet. Set dc->writeback_running false as no writeback thread created in bch_cached_dev_writeback_init(). We have writeback thread created and woken up in bch_cached_dev_writeback _start(). Set dc->writeback_running true before bch_writeback_queue() called, as a writeback thread will check if dc->writeback_running is true before writing back dirty data, and hung if false detected. After the change, we can get the following output for a fresh standalone backing device: ----------------------- /sys/block/bcache0/bcache$ cat writeback_running 0 /sys/block/bcache0/bcache# cat writeback_rate_debug rate: 0.0k/sec dirty: 0.0k target: 0.0k proportional: 0.0k integral: 0.0k change: 0.0k/sec next io: 0ms v1 -> v2: Set dc->writeback_running before bch_writeback_queue() called, Signed-off-by: Shenghui Wang Signed-off-by: Coly Li Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/md/bcache/writeback.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index ba5395fd386d5..b5fc3c6c7178e 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -781,7 +781,7 @@ void bch_cached_dev_writeback_init(struct cached_dev *dc) bch_keybuf_init(&dc->writeback_keys); dc->writeback_metadata = true; - dc->writeback_running = true; + dc->writeback_running = false; dc->writeback_percent = 10; dc->writeback_delay = 30; atomic_long_set(&dc->writeback_rate.rate, 1024); @@ -810,6 +810,7 @@ int bch_cached_dev_writeback_start(struct cached_dev *dc) destroy_workqueue(dc->writeback_write_wq); return PTR_ERR(dc->writeback_thread); } + dc->writeback_running = true; WARN_ON(test_and_set_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags)); schedule_delayed_work(&dc->writeback_rate_update, -- 2.20.1