Return-Path: Received: from mail-qk0-f169.google.com ([209.85.220.169]:36779 "EHLO mail-qk0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753297AbbKQLxU (ORCPT ); Tue, 17 Nov 2015 06:53:20 -0500 Received: by qkda6 with SMTP id a6so1673664qkd.3 for ; Tue, 17 Nov 2015 03:53:19 -0800 (PST) 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> 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-nfs-owner@vger.kernel.org List-ID: 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)) { -- 2.4.3