Not really for the patch, but given that we have the right people on CC:
Do we really want to keep DAX support in ext2 in the long run? ext2 is missing a lot of the useful features for a modern FS, shouldn't we direct people to use ext4 (in non-journal mode if needed) if they want to use DAX? ext4 will even support the unmodified ext2 fs, so it shouldn't be a big hurdle, and it would avoid a lot of churn in ext2.
