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=-5.7 required=3.0 tests=DATE_IN_PAST_03_06, DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 1836AC33CAF for ; Wed, 22 Jan 2020 13:20:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E300F24691 for ; Wed, 22 Jan 2020 13:20:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579699242; bh=XPBQSiM5KqGKjrSjNzH8x1J5nmiAzP2iCbS/ejLm77Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=lQ/2uW8modtR7BGxtowujLk9yIH22+HOV5dTPjwtZvPrB893xvG7WttxfYuUSVuZz l2/OMFwyMWERv4HU8QDioNs9hvWTkPlbC0jTkkWazv8VpKhFPz+NKOslOvzOEB2L4K MnmtUJck0JHG+bxPxccQ5tMUgJNyBlMdNFb8kWbQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726605AbgAVNUk (ORCPT ); Wed, 22 Jan 2020 08:20:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:37000 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726590AbgAVNUj (ORCPT ); Wed, 22 Jan 2020 08:20:39 -0500 Received: from localhost (unknown [84.241.205.26]) (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 BB6242467A; Wed, 22 Jan 2020 13:20:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579699239; bh=XPBQSiM5KqGKjrSjNzH8x1J5nmiAzP2iCbS/ejLm77Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LYSvb5k/kG9rfgyMhZazAR13iB8fqucMN9PKy9usBWGZQrVjjpV/ZGqs6/dGUAc4H TOmLREIzdlKFiUBxRczo84CYNvSoMljCyAQ2JavdJlmZYAOuMQRCEkM3FPOSqbsFap 87sQxBy+u6IBS94NS3IrZLJCJH9zr7Rc4Epy01Gg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josef Bacik , David Sterba Subject: [PATCH 5.4 084/222] btrfs: fix invalid removal of root ref Date: Wed, 22 Jan 2020 10:27:50 +0100 Message-Id: <20200122092839.725614756@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200122092833.339495161@linuxfoundation.org> References: <20200122092833.339495161@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Josef Bacik commit d49d3287e74ffe55ae7430d1e795e5f9bf7359ea upstream. If we have the following sequence of events btrfs sub create A btrfs sub create A/B btrfs sub snap A C mkdir C/foo mv A/B C/foo rm -rf * We will end up with a transaction abort. The reason for this is because we create a root ref for B pointing to A. When we create a snapshot of C we still have B in our tree, but because the root ref points to A and not C we will make it appear to be empty. The problem happens when we move B into C. This removes the root ref for B pointing to A and adds a ref of B pointing to C. When we rmdir C we'll see that we have a ref to our root and remove the root ref, despite not actually matching our reference name. Now btrfs_del_root_ref() allowing this to work is a bug as well, however we know that this inode does not actually point to a root ref in the first place, so we shouldn't be calling btrfs_del_root_ref() in the first place and instead simply look up our dir index for this item and do the rest of the removal. CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/inode.c | 27 +++++++++++++++++++-------- 1 file changed, 19 insertions(+), 8 deletions(-) --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -4260,13 +4260,16 @@ static int btrfs_unlink_subvol(struct bt } btrfs_release_path(path); - ret = btrfs_del_root_ref(trans, objectid, root->root_key.objectid, - dir_ino, &index, name, name_len); - if (ret < 0) { - if (ret != -ENOENT) { - btrfs_abort_transaction(trans, ret); - goto out; - } + /* + * This is a placeholder inode for a subvolume we didn't have a + * reference to at the time of the snapshot creation. In the meantime + * we could have renamed the real subvol link into our snapshot, so + * depending on btrfs_del_root_ref to return -ENOENT here is incorret. + * Instead simply lookup the dir_index_item for this entry so we can + * remove it. Otherwise we know we have a ref to the root and we can + * call btrfs_del_root_ref, and it _shouldn't_ fail. + */ + if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID) { di = btrfs_search_dir_index_item(root, path, dir_ino, name, name_len); if (IS_ERR_OR_NULL(di)) { @@ -4281,8 +4284,16 @@ static int btrfs_unlink_subvol(struct bt leaf = path->nodes[0]; btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); index = key.offset; + btrfs_release_path(path); + } else { + ret = btrfs_del_root_ref(trans, objectid, + root->root_key.objectid, dir_ino, + &index, name, name_len); + if (ret) { + btrfs_abort_transaction(trans, ret); + goto out; + } } - btrfs_release_path(path); ret = btrfs_delete_delayed_dir_index(trans, BTRFS_I(dir), index); if (ret) {