ftl: cache last virtual address translation

include/ftl.h

@@ -14,6 +14,8 @@ struct ftl_page_desc {
 
 struct ftl_map {
 	struct flash_dev *dev;
+	uint32_t last_va;
+	uint32_t last_pa;
 	uint32_t head, tail;
 	uint32_t root;
 	uint32_t nused_pages;

source/ftl/map.c

@@ -379,6 +379,9 @@ int trace_path(struct ftl_map *map, struct ftl_page_desc *new_page_desc,
 	uint8_t depth = 0;
 	uint32_t upage = map->root;
 
+	if (map->last_va == va)
+		return map->last_pa;
+
 	if (new_page_desc)
 		new_page_desc->va = va;
 
@@ -414,6 +417,9 @@ int trace_path(struct ftl_map *map, struct ftl_page_desc *new_page_desc,
 	if (page)
 		*page = upage;
 
+	map->last_va = va;
+	map->last_pa = upage;
+
 	return 0;
 
 err_not_found: