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=-6.8 required=3.0 tests=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 35075C2D0DB for ; Wed, 22 Jan 2020 09:48:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 05A0F2467C for ; Wed, 22 Jan 2020 09:48:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579686488; bh=AkLuwjehgQMV0NZu73AEcKFSv7+rcuwhSHUnoRBjyls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=LBLiXUsljys4KKO3vCYOjI3gCyoFajKxCExceBgWr5QszcMFqExx8c/xFoqc3PhPg UC3q/WmfdGFraUH5W/dFSdiB1grBROELT/nneuyia1hcFQ/Fm8yD9qkEngORFq9hZp CHUZtzzo3FrooUi4hn4RFUGrWy2P/pEwaNNvMWbQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729157AbgAVJsH (ORCPT ); Wed, 22 Jan 2020 04:48:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:33006 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387594AbgAVJlk (ORCPT ); Wed, 22 Jan 2020 04:41:40 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 2E27F2467B; Wed, 22 Jan 2020 09:41:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579686099; bh=AkLuwjehgQMV0NZu73AEcKFSv7+rcuwhSHUnoRBjyls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wxP2+j+t3M2aR0Jc1PyJNtXM2QY2zP0nDhPwDUHxUZLCA1AmNcA6qv26nc0OIctip 86ehSxQeA6iKchyNf15cC28qowGkxXFRjQlineinR6o6L4QYQAh5jWca4/9CXUvbbd BNSakbysiGYj18WiGQjWd9rIwOnwhuWC68T7zyEY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Josef Bacik , David Sterba Subject: [PATCH 4.19 043/103] btrfs: fix invalid removal of root ref Date: Wed, 22 Jan 2020 10:28:59 +0100 Message-Id: <20200122092810.346582942@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200122092803.587683021@linuxfoundation.org> References: <20200122092803.587683021@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 @@ -4168,13 +4168,16 @@ 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)) { @@ -4189,8 +4192,16 @@ 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) {