From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5BDAAC55186 for ; Wed, 22 Apr 2020 10:34:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3877320656 for ; Wed, 22 Apr 2020 10:34:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587551650; bh=cpi8xhq+oGMQDR0pcONOu5VnjZ2jS7IwZWsgpVsV+8s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=cMjvNI6hn6gaPjio7whxHBU7e179ZDpj0iMI9Yc57JE+Mi5CbP1dEYSm8/zIQPriS 43R1XXX4om5kHBLjNIRyVCYfQuCIWAiJVbTDgEg5pzlguDFMabZBZuyedf4sgDdKw3 ULDbQ8A6BD+QCiFmzRFcwMMOYI+seXcHwGh2I14o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731243AbgDVKeJ (ORCPT ); Wed, 22 Apr 2020 06:34:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:32844 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730426AbgDVKY3 (ORCPT ); Wed, 22 Apr 2020 06:24:29 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id ACC882075A; Wed, 22 Apr 2020 10:24:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1587551069; bh=cpi8xhq+oGMQDR0pcONOu5VnjZ2jS7IwZWsgpVsV+8s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iD+4igIjAGjChRl6LgDU+5PjVZkDG+Jk2MwZEzeZu2a8HcRrGn05n8JnoUshishQ8 /USGlP5pbSMa/an6wBPgjJ727yDNc68f91a+sUx4tu767Agvlgltsjv7f7zqoYGmfI X94FuQbmvyOi75YSN3IenPmrOBSYn8UCFRmbOTBU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guenter Roeck , Madhuparna Bhowmik , David Sterba , Sasha Levin Subject: [PATCH 5.6 088/166] btrfs: add RCU locks around block group initialization Date: Wed, 22 Apr 2020 11:56:55 +0200 Message-Id: <20200422095058.125383678@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200422095047.669225321@linuxfoundation.org> References: <20200422095047.669225321@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Madhuparna Bhowmik [ Upstream commit 29566c9c773456467933ee22bbca1c2b72a3506c ] The space_info list is normally RCU protected and should be traversed with rcu_read_lock held. There's a warning [29.104756] WARNING: suspicious RCU usage [29.105046] 5.6.0-rc4-next-20200305 #1 Not tainted [29.105231] ----------------------------- [29.105401] fs/btrfs/block-group.c:2011 RCU-list traversed in non-reader section!! pointing out that the locking is missing in btrfs_read_block_groups. However this is not necessary as the list traversal happens at mount time when there's no other thread potentially accessing the list. To fix the warning and for consistency let's add the RCU lock/unlock, the code won't be affected much as it's doing some lightweight operations. Reported-by: Guenter Roeck Signed-off-by: Madhuparna Bhowmik Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Sasha Levin --- fs/btrfs/block-group.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index 7f09147872dc7..c9a3bbc8c6afb 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1987,6 +1987,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info) btrfs_release_path(path); } + rcu_read_lock(); list_for_each_entry_rcu(space_info, &info->space_info, list) { if (!(btrfs_get_alloc_profile(info, space_info->flags) & (BTRFS_BLOCK_GROUP_RAID10 | @@ -2007,6 +2008,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info) list) inc_block_group_ro(cache, 1); } + rcu_read_unlock(); btrfs_init_global_block_rsv(info); ret = check_chunk_block_group_mappings(info); -- 2.20.1