From f68e26ac1268da755815f72d8fca3324ef5736ea Mon Sep 17 00:00:00 2001
From: "S.J.R. van Schaik" <stephan@whiteboxsystems.nl>
Date: Mon, 24 Jul 2017 13:12:54 +0200
Subject: [PATCH] ftl: implement flags to keep track of state

---
 include/ftl.h    | 5 +++++
 source/ftl/map.c | 6 +++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/ftl.h b/include/ftl.h
index b1e67ff..8464835 100644
--- a/include/ftl.h
+++ b/include/ftl.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <macros.h>
+
 struct ftl_page_group {
 	uint8_t magic[3];
 	uint8_t epoch;
@@ -14,6 +16,7 @@ struct ftl_page_desc {
 
 struct ftl_map {
 	struct flash_dev *dev;
+	unsigned flags;
 	uint32_t last_va;
 	uint32_t last_pa;
 	uint32_t head, tail;
@@ -28,6 +31,8 @@ struct ftl_map {
 	uint8_t epoch;
 };
 
+#define FTL_CACHED_VA BIT(0)
+
 #define FTL_MAX_ATTEMPTS 8
 
 int ftl_init_map(struct ftl_map *map, struct flash_dev *dev);
diff --git a/source/ftl/map.c b/source/ftl/map.c
index abce785..10c8f48 100644
--- a/source/ftl/map.c
+++ b/source/ftl/map.c
@@ -309,6 +309,9 @@ static void reset_map(struct ftl_map *map)
 
 	map->nblocks = flash_get_size(map->dev) >> map->log2_block_size;
 
+	map->flags = 0;
+	map->last_va = 0;
+	map->last_pa = 0;
 	map->head = 0;
 	map->tail = 0;
 	map->root = UINT32_MAX;
@@ -379,7 +382,7 @@ 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)
+	if ((map->flags & FTL_CACHED_VA) && map->last_va == va)
 		return map->last_pa;
 
 	if (new_page_desc)
@@ -417,6 +420,7 @@ int trace_path(struct ftl_map *map, struct ftl_page_desc *new_page_desc,
 	if (page)
 		*page = upage;
 
+	map->flags |= FTL_CACHED_VA;
 	map->last_va = va;
 	map->last_pa = upage;