From patchwork Tue Nov 17 11:52:24 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 7636671 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A7D18BF90C for ; Tue, 17 Nov 2015 11:55:27 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id D4630204EC for ; Tue, 17 Nov 2015 11:55:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0037D204E2 for ; Tue, 17 Nov 2015 11:55:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753375AbbKQLxW (ORCPT ); Tue, 17 Nov 2015 06:53:22 -0500 Received: from mail-qk0-f174.google.com ([209.85.220.174]:34170 "EHLO mail-qk0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751975AbbKQLxU (ORCPT ); Tue, 17 Nov 2015 06:53:20 -0500 Received: by qkfo3 with SMTP id o3so1683631qkf.1 for ; Tue, 17 Nov 2015 03:53:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=poochiereds_net.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=NMBRgq6RRHXtGPlu7FUdJFyfY3f0aZGLWOSAYCucGhk=; b=lvhe3uiTpFRFk5jdOqUr3spj7VS+/KtpCvYDR5hlL6UVjJ1yfUUfWVrZiw0cTRm9rl M+cS7E3eAm9p/3VGpsa3kNXzx4pt+j9ht7VIrscn33OOkiN0cbNGz2oj1NkzEzr3WlDz jSoKiDmTP94n3h+HMTKH14GApoUeC1l8v6Jj1RPTlWYyDi1d9pW5y8xzRl5d//aOfNYJ cajRkEnR2JDHR/IaDDCpsyVgeH4ICoRJDjLiPXXy4OIUQ9zva6OnliUKSmOyW8OJTz7P p2eYfe8MSjS7Pm/KbY6i+jzvoMqDnfsK73mQA/W+vttxn43Pj47OOp5EImTkyLqV7440 MOfg== 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:in-reply-to :references; bh=NMBRgq6RRHXtGPlu7FUdJFyfY3f0aZGLWOSAYCucGhk=; b=ce01E6fauVEpFNEHb4Tq+yqPgUW9pjJwt1Mfw5nZokQDrnHvUTIa7yBE4gslvEN+/U vFbU+j1n4kVih40gGYzRGO95FttjiReU20fyM04jg7WNDLfc2J/EO2vEoKdVmrVl1YTS CHySMh0xLZ1TGJA/03YefKbLGVy4WJw48CbdC6sHpxE0rTTJKFUvspZuvj/IISY3MTIB uW2yPv22h0lVCPxhXuVlM9Aq6Wd7wc6I4OEJceiQ7BWPDfUNGVkRjNMtQ8XwknFJndce FQNfY+1c6uoQnQ1/p+yRpG1d5qPmBVAdq6RCK9hCv4x508OjYvt8DQ1BtNf4218Vx3mP fWdw== X-Gm-Message-State: ALoCoQmLOVHfTUmLIIU+UWHcb992o5FRcfc2YSwxhts5Y5K0cbp7yFsO4x7XsCqQgrxRPf3G54Fr X-Received: by 10.55.71.81 with SMTP id u78mr41490164qka.81.1447761199453; Tue, 17 Nov 2015 03:53:19 -0800 (PST) Received: from tlielax.poochiereds.net ([2606:a000:1125:4075::d5a]) by smtp.googlemail.com with ESMTPSA id w10sm1583910qhc.16.2015.11.17.03.53.17 (version=TLSv1/SSLv3 cipher=OTHER); Tue, 17 Nov 2015 03:53:18 -0800 (PST) From: Jeff Layton X-Google-Original-From: Jeff Layton To: bfields@fieldses.org, trond.myklebust@primarydata.com Cc: linux-nfs@vger.kernel.org, Eric Paris , Alexander Viro , linux-fsdevel@vger.kernel.org Subject: [PATCH v1 02/38] fs: have flush_delayed_fput flush the workqueue job Date: Tue, 17 Nov 2015 06:52:24 -0500 Message-Id: <1447761180-4250-3-git-send-email-jeff.layton@primarydata.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1447761180-4250-1-git-send-email-jeff.layton@primarydata.com> References: <1447761180-4250-1-git-send-email-jeff.layton@primarydata.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-7.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD,T_DKIM_INVALID,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 immediately schedule the work to run if it's not already, and block until the workqueue job completes. Cc: Al Viro 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 ad17e05ebf95..52cc6803c07a 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -244,6 +244,8 @@ 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 @@ -256,11 +258,9 @@ 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)) {