From patchwork Tue Sep 1 17:35:53 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 7106311 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 9DDC19F36E for ; Tue, 1 Sep 2015 17:36:39 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id C85B62061E for ; Tue, 1 Sep 2015 17:36:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C416C2060D for ; Tue, 1 Sep 2015 17:36:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753466AbbIARgH (ORCPT ); Tue, 1 Sep 2015 13:36:07 -0400 Received: from mail-qk0-f180.google.com ([209.85.220.180]:34968 "EHLO mail-qk0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753189AbbIARgG (ORCPT ); Tue, 1 Sep 2015 13:36:06 -0400 Received: by qkcj187 with SMTP id j187so51746889qkc.2 for ; Tue, 01 Sep 2015 10:36:05 -0700 (PDT) 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; bh=YJI3kHW5Bedzzj9bBZVHYMQycTxwoyMLjutGYKv7qEw=; b=NhmgrpOY9gmXqnazZH5jM6gv1yYlAl9X3ucmZwNolfpO/ArqWNoGdFifVztsBBG4Wk rp9lcnnfOlsmL/qjOruF14og88cm8tNCs7m3Sn5ZwnCyP6GwUGVzo7oIa+z1YM+5rbeS 1W2xYmYvjgsmArkP4AVkROq0SQKpryXIi2yrA/YapUsGx9939HkBGqBxCoYEzVTg4py0 kgxqsW34IvEWLxiUJD0RYz6GZMBB/ZzajU8fVTHErjHMeulbDllRV2Cyjxf5SbWO/TX5 9gsHTqQIZDVYZuPmzE9btdJ7UXsoMc3Gtud/dmHv8S5J54ASI5UT1J1H//BFJTT0TsEP xZNg== X-Gm-Message-State: ALoCoQnf7ju2z63EB/UUhhS0+x7YrLAmBnx3d+Lt1nFX0W50dUGbhdD0NoxvHYzqLXqNHjyX/xYy X-Received: by 10.55.26.218 with SMTP id l87mr21239628qkh.23.1441128964924; Tue, 01 Sep 2015 10:36:04 -0700 (PDT) Received: from tlielax.poochiereds.net ([2606:a000:1105:8e:3a60:77ff:fe93:a95d]) by smtp.googlemail.com with ESMTPSA id 49sm11211455qgh.4.2015.09.01.10.36.03 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 01 Sep 2015 10:36:04 -0700 (PDT) From: Jeff Layton X-Google-Original-From: Jeff Layton To: Alexander Viro Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] fs: have flush_delayed_fput flush the workqueue job Date: Tue, 1 Sep 2015 13:35:53 -0400 Message-Id: <1441128953-16577-1-git-send-email-jeff.layton@primarydata.com> X-Mailer: git-send-email 2.4.3 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP I think there's a potential race in flush_delayed_fput. A kthread does an fput() and that file gets added to the list and the delayed work is scheduled. More than 1 jiffy passes, and the workqueue thread picks up the work and starts running it. Then the kthread calls flush_delayed_work. It sees that the list is empty and returns immediately, even though the __fput for its file may not have run yet. Close this by making flush_delayed_fput use flush_delayed_work instead, which should just block until the workqueue job completes if it's already running. Signed-off-by: Jeff Layton --- fs/file_table.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/file_table.c b/fs/file_table.c index 7f9d407c7595..f4833af62eae 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -243,6 +243,8 @@ static void ____fput(struct callback_head *work) __fput(container_of(work, struct file, f_u.fu_rcuhead)); } +static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput); + /* * If kernel thread really needs to have the final fput() it has done * to complete, call this. The only user right now is the boot - we @@ -255,11 +257,9 @@ static void ____fput(struct callback_head *work) */ void flush_delayed_fput(void) { - delayed_fput(NULL); + flush_delayed_work(&delayed_fput_work); } -static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput); - void fput(struct file *file) { if (atomic_long_dec_and_test(&file->f_count)) {