From patchwork Thu Aug 6 14:39:36 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhaolei X-Patchwork-Id: 6960431 Return-Path: X-Original-To: patchwork-linux-btrfs@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 3C4BB9F358 for ; Thu, 6 Aug 2015 14:41:25 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id F3AA3206DF for ; Thu, 6 Aug 2015 14:41:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 174A1206D9 for ; Thu, 6 Aug 2015 14:41:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754305AbbHFOlS (ORCPT ); Thu, 6 Aug 2015 10:41:18 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:48124 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753278AbbHFOlS (ORCPT ); Thu, 6 Aug 2015 10:41:18 -0400 X-IronPort-AV: E=Sophos;i="5.15,520,1432569600"; d="scan'208";a="99348093" Received: from unknown (HELO edo.cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 06 Aug 2015 22:44:39 +0800 Received: from G08CNEXCHPEKD01.g08.fujitsu.local (localhost.localdomain [127.0.0.1]) by edo.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id t76EdHTh021421 for ; Thu, 6 Aug 2015 22:39:17 +0800 Received: from localhost.localdomain (10.167.226.114) by G08CNEXCHPEKD01.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server id 14.3.181.6; Thu, 6 Aug 2015 22:41:12 +0800 From: Zhao Lei To: CC: Zhao Lei Subject: [PATCH] btrfs: Add WARN_ON() for double lock in btrfs_tree_lock() Date: Thu, 6 Aug 2015 22:39:36 +0800 Message-ID: <68cb57b7e339dd1270037d8f6694a5dccf340688.1438871972.git.zhaolei@cn.fujitsu.com> X-Mailer: git-send-email 1.8.5.1 MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-7.0 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, 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 When a task trying to double lock a extent buffer, there are no lockdep warning about it because this lock may be in "blocking_lock" state, and make us hard to debug. This patch add a WARN_ON() for above condition, it can not report all deadlock cases(as lock between tasks), but at least helps us some. Signed-off-by: Zhao Lei --- fs/btrfs/locking.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index f8229ef..d7e6baf 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -241,6 +241,7 @@ void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb) */ void btrfs_tree_lock(struct extent_buffer *eb) { + WARN_ON(eb->lock_owner == current->pid); again: wait_event(eb->read_lock_wq, atomic_read(&eb->blocking_readers) == 0); wait_event(eb->write_lock_wq, atomic_read(&eb->blocking_writers) == 0);