ftl: initialise the offset in the map

source/ftl/map.c

@@ -312,6 +312,7 @@ static void reset_map(struct ftl_map *map)
 	map->flags = 0;
 	map->last_va = 0;
 	map->last_pa = 0;
+	map->offset = 0;
 	map->head = 0;
 	map->tail = 0;
 	map->root = UINT32_MAX;