Btrfs: Optimize allocations as we need to mix data and metadata into one group

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index d82afb6..f7907b0 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -279,6 +279,8 @@
 
 
 #define BTRFS_BLOCK_GROUP_DATA 1
+#define BTRFS_BLOCK_GROUP_MIXED 2
+
 struct btrfs_block_group_item {
 	__le64 used;
 	u8 flags;