Btrfs: Rev the disk format

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index cecf29e..b305ae7 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -40,7 +40,7 @@
 extern struct kmem_cache *btrfs_path_cachep;
 struct btrfs_ordered_sum;
 
-#define BTRFS_MAGIC "_B6RfS_M"
+#define BTRFS_MAGIC "_B7RfS_M"
 
 #define BTRFS_ACL_NOT_CACHED    ((void *)-1)