From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752115AbdGOBlj (ORCPT ); Fri, 14 Jul 2017 21:41:39 -0400 Received: from omzsmtpe01.verizonbusiness.com ([199.249.25.210]:25549 "EHLO omzsmtpe01.verizonbusiness.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751146AbdGOB1N (ORCPT ); Fri, 14 Jul 2017 21:27:13 -0400 X-IronPort-Anti-Spam-Filtered: false From: "Levin, Alexander (Sasha Levin)" Cc: Liu Bo , David Sterba , "Levin, Alexander (Sasha Levin)" X-Host: ranger.odc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH for v4.9 LTS 34/87] Btrfs: use down_read_nested to make lockdep silent Thread-Topic: [PATCH for v4.9 LTS 34/87] Btrfs: use down_read_nested to make lockdep silent Thread-Index: AQHS/QlVghoaC8tRa0ylYhueYWBYbQ== Date: Sat, 15 Jul 2017 01:26:08 +0000 Message-ID: <20170715012538.10101-34-alexander.levin@verizon.com> References: <20170715012538.10101-1-alexander.levin@verizon.com> In-Reply-To: <20170715012538.10101-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v6F1fxSv023337 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 --- fs/btrfs/extent-tree.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index e46e7fbe1b34..14a37ff0b9e3 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -7401,7 +7401,8 @@ btrfs_lock_cluster(struct btrfs_block_group_cache *block_group, 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) -- 2.11.0