Btrfs: add a radix back bit tree

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/bit-radix.h b/fs/btrfs/bit-radix.h
new file mode 100644
index 0000000..56aad4c
--- /dev/null
+++ b/fs/btrfs/bit-radix.h
@@ -0,0 +1,15 @@
+#ifndef __BIT_RADIX__
+#define __BIT_RADIX__
+#include <linux/radix-tree.h>
+
+int set_radix_bit(struct radix_tree_root *radix, unsigned long bit);
+int test_radix_bit(struct radix_tree_root *radix, unsigned long bit);
+int clear_radix_bit(struct radix_tree_root *radix, unsigned long bit);
+int find_first_radix_bit(struct radix_tree_root *radix, unsigned long *retbits,
+			 int nr);
+
+static inline void init_bit_radix(struct radix_tree_root *radix)
+{
+	INIT_RADIX_TREE(radix, GFP_NOFS);
+}
+#endif