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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4ECEAC32772 for ; Tue, 23 Aug 2022 11:47:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358243AbiHWLrX (ORCPT ); Tue, 23 Aug 2022 07:47:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42222 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358505AbiHWLl6 (ORCPT ); Tue, 23 Aug 2022 07:41:58 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9E7D6CD522; Tue, 23 Aug 2022 02:29:29 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id B4D78B81C89; Tue, 23 Aug 2022 09:29:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 102BCC433D7; Tue, 23 Aug 2022 09:29:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661246966; bh=B3zGsGDfwsKUCKjNNbNoQ75m+V5P0+MQ8gQ4lFU8/9U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xyUnKTOiHC0nvrRgGcT3nrbCm9iqQnCBtYa8YTuJ+0d2apczRLt76l10JvrzjKyI6 42o23cd/hnrDZytYlzkLQ32SQSy6aiZQ0MPv59ltTl/S6FFjjIbtXQykrQ6YzBhFCn gRezXLitmTEiKRnIdPIGL3FqNULdc0pSuiW1u9lU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Qu Wenruo , David Sterba Subject: [PATCH 5.4 276/389] btrfs: reject log replay if there is unsupported RO compat flag Date: Tue, 23 Aug 2022 10:25:54 +0200 Message-Id: <20220823080127.064820431@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080115.331990024@linuxfoundation.org> References: <20220823080115.331990024@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Qu Wenruo commit dc4d31684974d140250f3ee612c3f0cab13b3146 upstream. [BUG] If we have a btrfs image with dirty log, along with an unsupported RO compatible flag: log_root 30474240 ... compat_flags 0x0 compat_ro_flags 0x40000003 ( FREE_SPACE_TREE | FREE_SPACE_TREE_VALID | unknown flag: 0x40000000 ) Then even if we can only mount it RO, we will still cause metadata update for log replay: BTRFS info (device dm-1): flagging fs with big metadata feature BTRFS info (device dm-1): using free space tree BTRFS info (device dm-1): has skinny extents BTRFS info (device dm-1): start tree-log replay This is definitely against RO compact flag requirement. [CAUSE] RO compact flag only forces us to do RO mount, but we will still do log replay for plain RO mount. Thus this will result us to do log replay and update metadata. This can be very problematic for new RO compat flag, for example older kernel can not understand v2 cache, and if we allow metadata update on RO mount and invalidate/corrupt v2 cache. [FIX] Just reject the mount unless rescue=nologreplay is provided: BTRFS error (device dm-1): cannot replay dirty log with unsupport optional features (0x40000000), try rescue=nologreplay instead We don't want to set rescue=nologreply directly, as this would make the end user to read the old data, and cause confusion. Since the such case is really rare, we're mostly fine to just reject the mount with an error message, which also includes the proper workaround. CC: stable@vger.kernel.org #4.9+ Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/disk-io.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2970,6 +2970,20 @@ int open_ctree(struct super_block *sb, err = -EINVAL; goto fail_csum; } + /* + * We have unsupported RO compat features, although RO mounted, we + * should not cause any metadata write, including log replay. + * Or we could screw up whatever the new feature requires. + */ + if (unlikely(features && btrfs_super_log_root(disk_super) && + !btrfs_test_opt(fs_info, NOLOGREPLAY))) { + btrfs_err(fs_info, +"cannot replay dirty log with unsupported compat_ro features (0x%llx), try rescue=nologreplay", + features); + err = -EINVAL; + goto fail_alloc; + } + ret = btrfs_init_workqueues(fs_info, fs_devices); if (ret) {