ftl: use write_page_desc() in ftl_trim()

source/ftl/ftl.c

@@ -125,7 +125,10 @@ int ftl_trim(struct ftl_map *map, uint32_t va)
 		alt_page << map->log2_page_size, 1 << map->log2_page_size) == 0)
 		return -1;
 
-	return write_upage(map, NULL, &page_desc);
+	if (prepare_head(map) < 0)
+		return -1;
+
+	return write_page_desc(map, &page_desc);
 }
 
 /* Returns the amount of used pages with a unique virtual address multiplied by

source/ftl/map.c

@@ -83,7 +83,7 @@ int read_page_desc(struct ftl_map *map,
 /* Writes the page descriptor to the footer of the current page group and
  * increments the head to point to the next free user page.
  */
-static int write_page_desc(struct ftl_map *map,
+int write_page_desc(struct ftl_map *map,
 	const struct ftl_page_desc *page_desc)
 {
 	struct ftl_page_group group;

source/ftl/map.h

@@ -6,6 +6,8 @@ int read_page_group(struct ftl_map *map,
 	struct ftl_page_group *group, uint32_t group_no);
 int read_page_desc(struct ftl_map *map,
 	struct ftl_page_desc *page_desc, uint32_t upage);
+int write_page_desc(struct ftl_map *map,
+	const struct ftl_page_desc *page_desc);
 int write_upage(struct ftl_map *map, const void *page,
 	const struct ftl_page_desc *page_desc);
 int trace_path(struct ftl_map *map, struct ftl_page_desc *new_page_desc,