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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 7DC98C3815B for ; Wed, 15 Apr 2020 11:53:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5111C206A2 for ; Wed, 15 Apr 2020 11:53:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586951620; bh=f+MIyflL7PoUCPvmXSbksyJDbP3lDfOTiJtP3BLlWqs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=FEYr1uC/PYBIiVQDR4vWKyHr2VUkANMtt+o/rkrenGDkfBY+OarNH7T61YrrVEFeX opPv0FsL773tA+SOOBpAWyPjORU/L53hr7tSsfHAWGPBfxcYXEJep+M//RDrszn4MJ Yms7s9/cZ3kuzYBchaSU1dWHaBHmgW4n74iND8i4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2897822AbgDOLxf (ORCPT ); Wed, 15 Apr 2020 07:53:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:37406 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406162AbgDOLpQ (ORCPT ); Wed, 15 Apr 2020 07:45:16 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A52E820737; Wed, 15 Apr 2020 11:45:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586951116; bh=f+MIyflL7PoUCPvmXSbksyJDbP3lDfOTiJtP3BLlWqs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AVKZvrjzvZKjfyxuV31HsD/pSiG7pCGZ03jzwkZ4o0wiftoAP1a3CU6rfqrNumRZZ w9TC8dPkVPrfkWAKwXlokfDJcyFXZraNeZqWn9TwA/a5O0zQzGzivFye5hDx7TYMBe t1XgEWipX14jNd1MYQRFN+CmTtIvunHjrisjq1rw= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Madhuparna Bhowmik , Guenter Roeck , David Sterba , Sasha Levin , linux-btrfs@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 30/84] btrfs: add RCU locks around block group initialization Date: Wed, 15 Apr 2020 07:43:47 -0400 Message-Id: <20200415114442.14166-30-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200415114442.14166-1-sashal@kernel.org> References: <20200415114442.14166-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 7dcfa7d7632a1..95330f40f998c 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1829,6 +1829,7 @@ int btrfs_read_block_groups(struct btrfs_fs_info *info) } } + 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 | @@ -1849,6 +1850,7 @@ 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