ufs2 fails to mount on x86_64, claiming bad magic. This is because
ufs_super_block_third's fs_un1 member is padded out by 4 bytes for 8-byte
alignment, pushing down the rest of the struct.
Forcing this to be packed solves it. I took a quick look over other
on-disk structures and didn't immediately find other problems. I was able
to mount & ls a populated ufs2 filesystem w/ this change.
Signed-off-by: Eric Sandeen <sandeen@redhat.com> Cc: Evgeniy Dushistov <dushistov@mail.ru> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>