ftl: add buffer length to ftl_read()

include/ftl.h

@@ -31,7 +31,7 @@ struct ftl_journal {
 int ftl_init_journal(struct ftl_journal *j, struct flash_dev *dev);
 int ftl_resume_journal(struct ftl_journal *j);
 int ftl_write(struct ftl_journal *j, uint32_t addr, const uint8_t *data);
-int ftl_read(struct ftl_journal *j, uint8_t *data, uint32_t va);
+int ftl_read(struct ftl_journal *j, uint8_t *data, size_t len, uint32_t va);
 int ftl_trim(struct ftl_journal *j, uint32_t va);
 uint32_t ftl_get_size(const struct ftl_journal *j);
 uint32_t ftl_get_capacity(const struct ftl_journal *j);

source/ftl/ftl.c

@@ -582,21 +582,21 @@ static int ftl_write_upage(struct ftl_journal *j, const uint8_t *page,
 	return ftl_write_page_desc(j, page_desc);
 }
 
-int ftl_read(struct ftl_journal *j, uint8_t *data, uint32_t va)
+int ftl_read(struct ftl_journal *j, uint8_t *data, size_t len, uint32_t va)
 {
 	int ret;
 	uint32_t page;
 
 	if ((ret = trace_path(j, NULL, &page, va)) < 0) {
-		if (ret != -ERR_NOT_FOUND)
-			return -1;
+		memset(data, 0, len);
+		return ret;
+	}
 
-		memset(data, 0, j->log2_page_size);
+	if (!data)
 		return 0;
-	}
 
 	return flash_read(j->dev, page << j->log2_page_size, data,
-		j->log2_page_size);
+		min(j->log2_page_size, len));
 }
 
 int ftl_write(struct ftl_journal *j, uint32_t va, const uint8_t *data)