From patchwork Mon Oct 5 11:02:24 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 7326661 Return-Path: X-Original-To: patchwork-linux-nfs@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 4B7169F6E4 for ; Mon, 5 Oct 2015 11:04:20 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6BDD2206EB for ; Mon, 5 Oct 2015 11:04:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A60A206E9 for ; Mon, 5 Oct 2015 11:04:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751052AbbJELEL (ORCPT ); Mon, 5 Oct 2015 07:04:11 -0400 Received: from mail-qk0-f178.google.com ([209.85.220.178]:35646 "EHLO mail-qk0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751024AbbJELCv (ORCPT ); Mon, 5 Oct 2015 07:02:51 -0400 Received: by qkap81 with SMTP id p81so66922973qka.2 for ; Mon, 05 Oct 2015 04:02:50 -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:in-reply-to :references; bh=LzW73ddcDK2zLb19U3CO1cZ9rBJKy4M+Sh9wpK3nj0Y=; b=Bb0tvUjhmTO2uoY72rj6SrDroidvB+h+U3FSGh5+PkQKZ+JT/eVGo0cDfcNJDwnhHH jFfiUlRuJkozNp4Xy3fbJP4DgshFO8tSt+V7FUZW1jzAI2RBbogboftQ0hyonrJcxNIj e23kU4P1dlYl4Z+NEQIvZXi+2OC5uC8RxhgA0iNIpmFtXwuksNawQsZE7JSyp2562lDM AzsFORAfvnyOC4VfP826NmwctPM2w66SLEEn3QsHoGfRcAS9fVV7FThAI9N2U9k47u8w sBcTVw47FcP1pb+BInP3nHVWcXrOeTtRIFunCv9ahi70ZzkPlhEHz3u6rRQce5kTxCvl 5OjQ== X-Gm-Message-State: ALoCoQkgr3Ie0wGA8t/h9vIpaTOlpn6yZEjTtZfEvVF3SU/Cisl60j+Qj+2URFITUjdEO/ZJpfbU X-Received: by 10.55.215.156 with SMTP id t28mr1372243qkt.68.1444042970689; Mon, 05 Oct 2015 04:02:50 -0700 (PDT) Received: from tlielax.poochiereds.net ([2606:a000:1125:6079::d5a]) by smtp.googlemail.com with ESMTPSA id p39sm4977719qkp.47.2015.10.05.04.02.49 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 05 Oct 2015 04:02:49 -0700 (PDT) From: Jeff Layton X-Google-Original-From: Jeff Layton To: bfields@fieldses.org Cc: linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Al Viro Subject: [PATCH v5 02/20] fs: have flush_delayed_fput flush the workqueue job Date: Mon, 5 Oct 2015 07:02:24 -0400 Message-Id: <1444042962-6947-3-git-send-email-jeff.layton@primarydata.com> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1444042962-6947-1-git-send-email-jeff.layton@primarydata.com> References: <1444042962-6947-1-git-send-email-jeff.layton@primarydata.com> Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@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 immediately schedule the work to run if it's not already, and block until the workqueue job completes. 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)) {