[PATCH] fix UFS superblock alignment issues

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>

include/linux/ufs_fs.h

@@ -908,7 +908,7 @@ struct ufs_super_block_third {
 			__fs64   fs_csaddr;	/* blk addr of cyl grp summary area */
 			__fs64    fs_pendingblocks;/* blocks in process of being freed */
 			__fs32    fs_pendinginodes;/*inodes in process of being freed */
-		} fs_u2;
+		} __attribute__ ((packed)) fs_u2;
 	} fs_un1;
 	union {
 		struct {