Btrfs: groundwork for subvolume and snapshot roots

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/bit-radix.c b/fs/btrfs/bit-radix.c
index 783f54c..9fc42e9 100644
--- a/fs/btrfs/bit-radix.c
+++ b/fs/btrfs/bit-radix.c
@@ -86,7 +86,7 @@
 	int i;
 	int total_found = 0;
 
-	ret = radix_tree_gang_lookup(radix, (void *)&gang, 0, ARRAY_SIZE(gang));
+	ret = radix_tree_gang_lookup(radix, (void **)gang, 0, ARRAY_SIZE(gang));
 	for (i = 0; i < ret && nr > 0; i++) {
 		found = 0;
 		bits = gang[i];