From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:58877 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752327AbcFFOaJ (ORCPT ); Mon, 6 Jun 2016 10:30:09 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Filipe Manana Subject: [PATCH 4.5 125/128] Btrfs: fix empty symlink after creating symlink and fsync parent dir Date: Sun, 5 Jun 2016 15:24:40 -0700 Message-Id: <20160605222325.200655938@linuxfoundation.org> In-Reply-To: <20160605222321.183131188@linuxfoundation.org> References: <20160605222321.183131188@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Filipe Manana commit 3f9749f6e9edcf8ec569fb542efc3be35e06e84a upstream. If we create a symlink, fsync its parent directory, crash/power fail and mount the filesystem, we end up with an empty symlink, which not only is useless it's also not allowed in linux (the man page symlink(2) is well explicit about that). So we just need to make sure to fully log an inode if it's a symlink, to ensure its inline extent gets logged, ensuring the same behaviour as ext3, ext4, xfs, reiserfs, f2fs, nilfs2, etc. Example reproducer: $ mkfs.btrfs -f /dev/sdb $ mount /dev/sdb /mnt $ mkdir /mnt/testdir $ sync $ ln -s /mnt/foo /mnt/testdir/bar $ xfs_io -c fsync /mnt/testdir $ mount /dev/sdb /mnt $ readlink /mnt/testdir/bar A test case for fstests follows soon. Signed-off-by: Filipe Manana Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/tree-log.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -5157,7 +5157,7 @@ process_leaf: } ctx->log_new_dentries = false; - if (type == BTRFS_FT_DIR) + if (type == BTRFS_FT_DIR || type == BTRFS_FT_SYMLINK) log_mode = LOG_INODE_ALL; btrfs_release_path(path); ret = btrfs_log_inode(trans, root, di_inode,