From patchwork Wed May 12 14:46:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 437968 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 00018C2BCC3 for ; Wed, 12 May 2021 16:45:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DCF10611AC for ; Wed, 12 May 2021 16:45:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244414AbhELQpx (ORCPT ); Wed, 12 May 2021 12:45:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:56996 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239049AbhELQjL (ORCPT ); Wed, 12 May 2021 12:39:11 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id DE9B261CDA; Wed, 12 May 2021 16:03:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620835393; bh=q7qdVnuUeIr08s+JvqQJbgO5qKDfyI/vrU5HwDnxXXc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MMtuD+v/2H0l4/EcNEWM7c/mMpptDKIuNs//DM7Zd5uvOEj9nAyBE90dSc34Ae4pt Kgi9J/GyMN3JeL6jxMQtrBXbsjJgcjVlZ7VuwT5cjbEiseld1damWYmWqyvrQxPdAL a80SNva0vfn2xRXfy2UH1mHUPkduO27NzbadxtoU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Filipe Manana , Johannes Thumshirn , Naohiro Aota , David Sterba , Sasha Levin Subject: [PATCH 5.12 326/677] btrfs: zoned: move log tree node allocation out of log_root_tree->log_mutex Date: Wed, 12 May 2021 16:46:12 +0200 Message-Id: <20210512144848.075752880@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512144837.204217980@linuxfoundation.org> References: <20210512144837.204217980@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Naohiro Aota [ Upstream commit e75f9fd194090e69c5ffd856ba89160683d343da ] Commit 6e37d2459941 ("btrfs: zoned: fix deadlock on log sync") pointed out a deadlock warning and removed mutex_{lock,unlock} of fs_info::tree_root->log_mutex. While it looks like it always cause a deadlock, we didn't see actual deadlock in fstests runs. The reason is log_root_tree->log_mutex != fs_info->tree_root->log_mutex, not taking the same lock. So, the warning was actually a false-positive. Since btrfs_alloc_log_tree_node() is protected only by fs_info->tree_root->log_mutex, we can (and should) move the code out of the lock scope of log_root_tree->log_mutex and silence the warning. Fixes: 6e37d2459941 ("btrfs: zoned: fix deadlock on log sync") Reviewed-by: Filipe Manana Reviewed-by: Johannes Thumshirn Signed-off-by: Naohiro Aota Signed-off-by: David Sterba Signed-off-by: Sasha Levin --- fs/btrfs/tree-log.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 92a368627791..72c4b66ed516 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -3165,20 +3165,22 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, */ mutex_unlock(&root->log_mutex); - btrfs_init_log_ctx(&root_log_ctx, NULL); - - mutex_lock(&log_root_tree->log_mutex); - if (btrfs_is_zoned(fs_info)) { + mutex_lock(&fs_info->tree_root->log_mutex); if (!log_root_tree->node) { ret = btrfs_alloc_log_tree_node(trans, log_root_tree); if (ret) { - mutex_unlock(&log_root_tree->log_mutex); + mutex_unlock(&fs_info->tree_log_mutex); goto out; } } + mutex_unlock(&fs_info->tree_root->log_mutex); } + btrfs_init_log_ctx(&root_log_ctx, NULL); + + mutex_lock(&log_root_tree->log_mutex); + index2 = log_root_tree->log_transid % 2; list_add_tail(&root_log_ctx.list, &log_root_tree->log_ctxs[index2]); root_log_ctx.log_transid = log_root_tree->log_transid;