From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Darrick J. Wong" Subject: [PATCH] ext2: don't mount filesystems with compat features we know only ext4 supports Date: Mon, 28 Sep 2015 15:36:26 -0700 Message-ID: <20150928223626.GI10390@birch.djwong.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4 , Dave Chinner , "Theodore Ts'o" To: Jan Kara Return-path: Received: from aserp1040.oracle.com ([141.146.126.69]:48690 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753431AbbI1Wgd (ORCPT ); Mon, 28 Sep 2015 18:36:33 -0400 Content-Disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: The ext2 mount code never checks the compat features against the ones it knows about. This is correct behavior since compat features are supposed to be rw-compatible with old drivers; however, for certain configurations (journalled rootfs) we probably want the ext4 driver to load, not ext2. Reported-by: Dave Chinner Signed-off-by: Darrick J. Wong --- fs/ext2/ext2.h | 6 +++++- fs/ext2/super.c | 13 ++++++++++--- 2 files changed, 15 insertions(+), 4 deletions(-) diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h index 8d15feb..ce508b1 100644 --- a/fs/ext2/ext2.h +++ b/fs/ext2/ext2.h @@ -547,7 +547,11 @@ struct ext2_super_block { #define EXT2_FEATURE_INCOMPAT_META_BG 0x0010 #define EXT2_FEATURE_INCOMPAT_ANY 0xffffffff -#define EXT2_FEATURE_COMPAT_SUPP EXT2_FEATURE_COMPAT_EXT_ATTR +#define EXT2_FEATURE_COMPAT_SUPP (EXT2_FEATURE_COMPAT_DIR_PREALLOC| \ + EXT2_FEATURE_COMPAT_IMAGIC_INODES| \ + EXT2_FEATURE_COMPAT_EXT_ATTR| \ + EXT2_FEATURE_COMPAT_RESIZE_INO| \ + EXT2_FEATURE_COMPAT_DIR_INDEX) #define EXT2_FEATURE_INCOMPAT_SUPP (EXT2_FEATURE_INCOMPAT_FILETYPE| \ EXT2_FEATURE_INCOMPAT_META_BG) #define EXT2_FEATURE_RO_COMPAT_SUPP (EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER| \ diff --git a/fs/ext2/super.c b/fs/ext2/super.c index 900e19c..4efb018 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -896,6 +896,16 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent) * previously didn't change the revision level when setting the flags, * so there is a chance incompat flags are set on a rev 0 filesystem. */ +#ifdef CONFIG_EXT4_FS + /* Journalled FS should mount with ext4 if it's available */ + features = EXT2_HAS_COMPAT_FEATURE(sb, ~EXT2_FEATURE_COMPAT_SUPP); + if (features) { + ext2_msg(sb, KERN_ERR, "error: won't mount because of " + "unsupported optional features (%x); try ext4", + le32_to_cpu(features)); + goto failed_mount; + } +#endif features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP); if (features) { ext2_msg(sb, KERN_ERR, "error: couldn't mount because of "