Btrfs: Better block record keeping, real mkfs

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index b30b2ce..1a4d1d6 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -223,6 +223,7 @@
 	int cache_size;
 	int fp;
 	struct btrfs_trans_handle *running_transaction;
+	struct btrfs_super_block *disk_super;
 };
 
 /*