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@xxxxxxxxxxxxx>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
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
> ---
> 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 <jack@xxxxxxxx>
SUSE Labs, CR
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