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Message-ID: <20150930163635.GK10390@birch.djwong.org> Date: Wed, 30 Sep 2015 09:36:35 -0700 From: "Darrick J. Wong" <darrick.wong@...cle.com> To: Jan Kara <jack@...e.cz> Cc: Jan Kara <jack@...e.com>, linux-ext4 <linux-ext4@...r.kernel.org>, Dave Chinner <david@...morbit.com>, "Theodore Ts'o" <tytso@....edu> Subject: Re: [PATCH] ext2: don't mount filesystems with compat features we know only ext4 supports On Wed, Sep 30, 2015 at 10:41:26AM +0200, Jan Kara wrote: > 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@...morbit.com> > > Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com> > > 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... I admit that refusing the mount might be a bit much; the goal here was merely to make it so that if the FS has a journal and ext4 was turned on, hopefully ext2 rejects the mount and ext4 will probe it next. <shrug> --D > > 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@...e.com> > SUSE Labs, CR > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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