Fix the node weight lookup for tree buckets by using a correct accessor.
Reflects ceph.git commit 
d287ade5bcbdca82a3aef145b92924cf1e856733.
Reviewed-by: Alex Elder <elder@inktank.com>
Signed-off-by: Sage Weil <sage@inktank.com>
 extern void crush_destroy_bucket(struct crush_bucket *b);
 extern void crush_destroy(struct crush_map *map);
 
+static inline int crush_calc_tree_node(int i)
+{
+       return ((i+1) << 1)-1;
+}
+
 #endif
 
        case CRUSH_BUCKET_LIST:
                return ((struct crush_bucket_list *)b)->item_weights[p];
        case CRUSH_BUCKET_TREE:
-               if (p & 1)
-                       return ((struct crush_bucket_tree *)b)->node_weights[p];
-               return 0;
+               return ((struct crush_bucket_tree *)b)->node_weights[crush_calc_tree_node(p)];
        case CRUSH_BUCKET_STRAW:
                return ((struct crush_bucket_straw *)b)->item_weights[p];
        }