Re: [PATCH] ext2: don't mount filesystems with compat features we know only ext4 supports
From: Jan Kara <jack@suse.cz>
Date: 2015-09-30 08:41:30
On Mon 28-09-15 15:36:26, Darrick J. Wong wrote:
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 <david@fromorbit.com> Signed-off-by: Darrick J. Wong <redacted>
Isn't this a bit too harsh? I agree we should at least warn (and that's probably regardless of EXT4 config option) but just refusing mount looks too much to me... Honza
quoted hunk ↗ jump to hunk
--- 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 "
-- Jan Kara [off-list ref] SUSE Labs, CR