From patchwork Wed Dec 22 15:27:48 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tetsuo Handa X-Patchwork-Id: 12691768 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BC1D9C433EF for ; Wed, 22 Dec 2021 15:28:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237674AbhLVP2F (ORCPT ); Wed, 22 Dec 2021 10:28:05 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:53677 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233787AbhLVP2E (ORCPT ); Wed, 22 Dec 2021 10:28:04 -0500 Received: from fsav116.sakura.ne.jp (fsav116.sakura.ne.jp [27.133.134.243]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 1BMFRr6C003199; Thu, 23 Dec 2021 00:27:53 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav116.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav116.sakura.ne.jp); Thu, 23 Dec 2021 00:27:53 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav116.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 1BMFRrDj003196 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Thu, 23 Dec 2021 00:27:53 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Message-ID: <9eff2034-2f32-54a3-e476-d0f609ab49c0@i-love.sakura.ne.jp> Date: Thu, 23 Dec 2021 00:27:48 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: [PATCH 2/2] loop: use task_work for autoclear operation Content-Language: en-US From: Tetsuo Handa To: linux-block , Christoph Hellwig , Jan Kara , Jens Axboe References: In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org The kernel test robot is reporting that xfstest can fail at umount ext2 on xfs umount xfs sequence, for commit 322c4293ecc58110 ("loop: make autoclear operation asynchronous") broke what commit ("loop: Make explicit loop device destruction lazy") wanted to achieve. Although we cannot guarantee that nobody is holding a reference when "umount xfs" is called, we should try to close a race window opened by asynchronous autoclear operation. Try to make the autoclear operation upon close() synchronous, by calling __loop_clr_fd() from current thread's task work rather than a WQ thread. Reported-by: kernel test robot Signed-off-by: Tetsuo Handa --- drivers/block/loop.c | 25 ++++++++++++++++++++----- drivers/block/loop.h | 5 ++++- 2 files changed, 24 insertions(+), 6 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index b1b05c45c07c..814605e2cbef 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1175,10 +1175,8 @@ static void loop_rundown_completed(struct loop_device *lo) module_put(THIS_MODULE); } -static void loop_rundown_workfn(struct work_struct *work) +static void loop_rundown_start(struct loop_device *lo) { - struct loop_device *lo = container_of(work, struct loop_device, - rundown_work); struct block_device *bdev = lo->lo_device; struct gendisk *disk = lo->lo_disk; @@ -1188,6 +1186,18 @@ static void loop_rundown_workfn(struct work_struct *work) loop_rundown_completed(lo); } +static void loop_rundown_callbackfn(struct callback_head *callback) +{ + loop_rundown_start(container_of(callback, struct loop_device, + rundown.callback)); +} + +static void loop_rundown_workfn(struct work_struct *work) +{ + loop_rundown_start(container_of(work, struct loop_device, + rundown.work)); +} + static void loop_schedule_rundown(struct loop_device *lo) { struct block_device *bdev = lo->lo_device; @@ -1195,8 +1205,13 @@ static void loop_schedule_rundown(struct loop_device *lo) __module_get(disk->fops->owner); kobject_get(&bdev->bd_device.kobj); - INIT_WORK(&lo->rundown_work, loop_rundown_workfn); - queue_work(system_long_wq, &lo->rundown_work); + if (!(current->flags & PF_KTHREAD)) { + init_task_work(&lo->rundown.callback, loop_rundown_callbackfn); + if (!task_work_add(current, &lo->rundown.callback, TWA_RESUME)) + return; + } + INIT_WORK(&lo->rundown.work, loop_rundown_workfn); + queue_work(system_long_wq, &lo->rundown.work); } static int loop_clr_fd(struct loop_device *lo) diff --git a/drivers/block/loop.h b/drivers/block/loop.h index 918a7a2dc025..596472f9cde3 100644 --- a/drivers/block/loop.h +++ b/drivers/block/loop.h @@ -56,7 +56,10 @@ struct loop_device { struct gendisk *lo_disk; struct mutex lo_mutex; bool idr_visible; - struct work_struct rundown_work; + union { + struct work_struct work; + struct callback_head callback; + } rundown; }; struct loop_cmd {