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=unavailable 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 EF5CBC38A29 for ; Wed, 15 Apr 2020 12:27:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C66BD208FE for ; Wed, 15 Apr 2020 12:27:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586953666; bh=f+MIyflL7PoUCPvmXSbksyJDbP3lDfOTiJtP3BLlWqs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=In+EdBwztuarAGVwxPvalEyJ1LANEuHmD10vpnZ64YkP8V2Ab239FwNbWJvZjWc5t mfKkqK1qp+gXiOViF2/+WgHAt0zVsviUnlHbOA7oDt5aegHTedFYrtQC+ARXuFlO/z JhMpQAGxIZ+i1tav/8t1I/U6bRZql1leJHvACC4o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2409160AbgDOLpU (ORCPT ); Wed, 15 Apr 2020 07:45:20 -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-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@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