to avoid the namespace problems caused by <ufs/ufs/inode.h> #defining
i_mode, etc.
ext2_fs_i.h had nothing to do with the Linux version. It was a small
part of the Linux version of ext2_fs.h (the part that declares extra
in-core fields for an inode). We don't need it because we use the
ufs in-core inode for the extra fields.