ftl: implement transactions to perform partial writes

include/ftl.h

@@ -19,6 +19,7 @@ struct ftl_map {
 	unsigned flags;
 	uint32_t last_va;
 	uint32_t last_pa;
+	uint32_t offset;
 	uint32_t head, tail;
 	uint32_t root;
 	uint32_t nused_pages;
@@ -33,6 +34,7 @@ struct ftl_map {
 
 #define FTL_CACHED_VA BIT(0)
 #define FTL_UNMAPPED  BIT(1)
+#define FTL_DIRTY     BIT(2)
 
 #define FTL_MAX_ATTEMPTS 8
 
@@ -42,6 +44,7 @@ int ftl_is_mapped(struct ftl_map *map, uint32_t va);
 size_t ftl_write(struct ftl_map *map, uint32_t addr, const void *data,
 	size_t len);
 size_t ftl_read(struct ftl_map *map, void *data, size_t len, uint32_t va);
+int ftl_sync(struct ftl_map *map);
 int ftl_trim(struct ftl_map *map, uint32_t va);
 uint32_t ftl_get_size(const struct ftl_map *map);
 uint32_t ftl_get_capacity(const struct ftl_map *map);

source/ftl/dev.c

@@ -53,7 +53,10 @@ static size_t ftl_flash_write(struct flash_dev *dev, uint32_t addr,
 {
 	struct ftl_map *map = dev->priv;
 
-	return ftl_write(map, addr, data, len);
+	len = ftl_write(map, addr, data, len);
+	ftl_sync(map);
+
+	return len;
 }
 
 static int ftl_flash_erase(struct flash_dev *dev, uint32_t addr)

source/ftl/ftl.c

@@ -41,61 +41,108 @@ size_t ftl_read(struct ftl_map *map, void *data, size_t len, uint32_t va)
 		len);
 }
 
-size_t ftl_write(struct ftl_map *map, uint32_t va, const void *udata,
-	size_t len)
+static int ftl_seek(struct ftl_map *map, uint32_t va)
 {
-	struct ftl_page_desc page_desc;
-	size_t nbytes;
+	size_t len;
 	int ret;
 	uint32_t offset, page, dst, src;
 
 	if (va >= ftl_get_capacity(map))
-		return 0;
+		return -1;
 
 	offset = va & ((1 << map->log2_page_size) - 1);
 	va >>= map->log2_page_size;
 
-	if ((ret = trace_path(map, &page_desc, &page, va)) < 0 &&
-		ret != -ERR_NOT_FOUND)
-		return 0;
+	if ((map->flags & FTL_CACHED_VA) && map->last_va != va &&
+		ftl_sync(map) < 0)
+		return -1;
 
-	if (ret == -ERR_NOT_FOUND)
-		++map->nused_pages;
+	if ((ret = trace_path(map, NULL, &page, va)) < 0 &&
+		ret != -ERR_NOT_FOUND)
+		return -1;
 
-	page_desc.nused_pages = map->nused_pages;
+	if (offset < map->offset)
+		return -1;
 
-	if (prepare_head(map) < 0)
+	if (offset == map->offset)
 		return 0;
 
+	if (map->offset == 0) {
+		if (prepare_head(map) < 0)
+			return -1;
+
+		if (ret == -ERR_NOT_FOUND)
+			++map->nused_pages;
+	}
+
 	dst = map->head << map->log2_page_size;
 	src = page << map->log2_page_size;
-	len = min(len, (1 << map->log2_page_size) - offset);
+	len = offset - map->offset;
 
 	if (ret == -ERR_NOT_FOUND)
-		flash_write0(map->dev, dst, offset);
+		flash_write0(map->dev, dst, len);
 	else
-		flash_copy(map->dev, dst, src, offset);
+		flash_copy(map->dev, dst, src, len);
 
-	src += offset;
-	dst += offset;
+	map->offset += len;
 
-	flash_write(map->dev, dst, udata, len);
+	return 0;
+}
 
-	src += len;
-	dst += len;
-	nbytes = (1 << map->log2_page_size) - len - offset;
+size_t ftl_write(struct ftl_map *map, uint32_t va, const void *udata,
+	size_t len)
+{
+	uint32_t dst;
 
-	if (ret == -ERR_NOT_FOUND)
-		flash_write0(map->dev, dst, nbytes);
-	else
-		flash_copy(map->dev, dst, src, nbytes);
+	if (ftl_seek(map, va) < 0)
+		return 0;
 
-	if (write_page_desc(map, &page_desc) < 0)
+	dst = (map->head << map->log2_page_size) + map->offset;
+	len = min(len, (1 << map->log2_page_size) - map->offset);
+
+	if ((len = flash_write(map->dev, dst, udata, len)) == 0)
 		return 0;
 
+	map->offset += len;
+	map->flags |= FTL_DIRTY;
+
 	return len;
 }
 
+int ftl_sync(struct ftl_map *map)
+{
+	struct ftl_page_desc page_desc;
+	size_t len;
+	int ret;
+	uint32_t page, dst, src;
+
+	if (!(map->flags & FTL_DIRTY))
+		return 0;
+
+	if ((ret = trace_path(map, &page_desc, &page, map->last_va)) < 0 &&
+		ret != -ERR_NOT_FOUND)
+		return -1;
+
+	dst = (map->head << map->log2_page_size) + map->offset;
+	src = (page << map->log2_page_size) + map->offset;
+	len = (1 << map->log2_page_size) - map->offset;
+
+	if (map->flags & FTL_UNMAPPED)
+		flash_write0(map->dev, dst, len);
+	else
+		flash_copy(map->dev, dst, src, len);
+
+	page_desc.nused_pages = map->nused_pages;
+
+	if (write_page_desc(map, &page_desc) < 0)
+		return -1;
+
+	map->offset = 0;
+	map->flags &= ~FTL_DIRTY;
+
+	return 0;
+}
+
 int ftl_trim(struct ftl_map *map, uint32_t va)
 {
 	struct ftl_page_desc page_desc, alt_page_desc;