From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753604AbdHDX00 (ORCPT ); Fri, 4 Aug 2017 19:26:26 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48124 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753083AbdHDX0Z (ORCPT ); Fri, 4 Aug 2017 19:26:25 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Liu Bo , David Sterba , Sasha Levin Subject: [PATCH 4.9 079/105] Btrfs: use down_read_nested to make lockdep silent Date: Fri, 4 Aug 2017 16:15:47 -0700 Message-Id: <20170804231556.531713229@linuxfoundation.org> X-Mailer: git-send-email 2.13.4 In-Reply-To: <20170804231551.544678194@linuxfoundation.org> References: <20170804231551.544678194@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Liu Bo [ Upstream commit e321f8a801d7b4c40da8005257b05b9c2b51b072 ] If @block_group is not @used_bg, it'll try to get @used_bg's lock without droping @block_group 's lock and lockdep has throwed a scary deadlock warning about it. Fix it by using down_read_nested. Signed-off-by: Liu Bo Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/extent-tree.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -7401,7 +7401,8 @@ btrfs_lock_cluster(struct btrfs_block_gr spin_unlock(&cluster->refill_lock); - down_read(&used_bg->data_rwsem); + /* We should only have one-level nested. */ + down_read_nested(&used_bg->data_rwsem, SINGLE_DEPTH_NESTING); spin_lock(&cluster->refill_lock); if (used_bg == cluster->block_group)