ftl: use byte-offset from VA in ftl_read()

source/ftl/ftl.c

@@ -15,7 +15,11 @@
 int ftl_read(struct ftl_map *map, void *data, size_t len, uint32_t va)
 {
 	int ret;
-	uint32_t page;
+	uint32_t mask, offset, page;
+
+	mask = ((1 << map->log2_page_size) - 1);
+	offset = va & mask;
+	va = va & ~mask;
 
 	if ((ret = trace_path(map, NULL, &page, va)) < 0) {
 		memset(data, 0, len);
@@ -25,8 +29,8 @@ int ftl_read(struct ftl_map *map, void *data, size_t len, uint32_t va)
 	if (!data)
 		return 0;
 
-	return flash_read(map->dev, page << map->log2_page_size, data,
-		min(map->log2_page_size, len));
+	return flash_read(map->dev, (page << map->log2_page_size) + offset, data,
+		min(map->log2_page_size - offset, len));
 }
 
 int ftl_write(struct ftl_map *map, uint32_t va, const uint8_t *data)