From 1d52ca46a634c844f6ab3e44e8cef365fde6b39d Mon Sep 17 00:00:00 2001
From: "S.J.R. van Schaik" <stephan@whiteboxsystems.nl>
Date: Mon, 12 Jun 2017 14:17:46 +0200
Subject: [PATCH] mufs: rework tree code to support
 mufs_map_page()/mufs_unmap_page()

---
 source/fs/mufs/tree.c | 42 ++++++++++++++++++++++++++++++++----------
 source/fs/mufs/tree.h |  2 ++
 2 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/source/fs/mufs/tree.c b/source/fs/mufs/tree.c
index 3e31293..2a3927a 100644
--- a/source/fs/mufs/tree.c
+++ b/source/fs/mufs/tree.c
@@ -13,7 +13,8 @@
 #include "tree.h"
 
 static int mufs_do_lookup(struct mufs *fs, uint32_t *page,
-	uint32_t base, uint8_t depth, uint32_t va, unsigned alloc)
+	uint32_t base, uint8_t depth, uint32_t va, uint32_t new_page,
+	unsigned alloc)
 {
 	struct flash_dev *dev = fs->dev;
 	char data[1 << dev->log2_block_size];
@@ -35,21 +36,35 @@ static int mufs_do_lookup(struct mufs *fs, uint32_t *page,
 	index = va & ((1 << ((depth - 1) * fs->log2_nentries)) - 1);
 
 	if (!table[index]) {
-		if (!alloc || mufs_alloc_block(fs, &table[index]) < 0)
+		if (depth > 1 && alloc && mufs_alloc_block(fs, &table[index]) < 0)
 			return -1;
 
+		if (depth == 1 && new_page)
+			table[index] = new_page;
+
 		if (flash_write(dev, base << dev->log2_block_size, data,
 			sizeof data) == 0)
 			return -1;
 	}
 
-	return mufs_do_lookup(fs, page, table[index], depth - 1, va, alloc);
+	return mufs_do_lookup(fs, page, table[index], depth - 1, va, new_page,
+		alloc);
 }
 
 int mufs_lookup_page(struct mufs_tree *tree, uint32_t *page,
 	uint32_t va)
 {
-	return mufs_do_lookup(tree->fs, page, tree->root, tree->depth, va, 0);
+	return mufs_do_lookup(tree->fs, page, tree->root, tree->depth, va, 0, 0);
+}
+
+int mufs_map_page(struct mufs_tree *tree, uint32_t va, uint32_t page)
+{
+	struct mufs *fs = tree->fs;
+
+	if (!tree->root && mufs_alloc_block(fs, &tree->root) < 0)
+		return -1;
+
+	return mufs_do_lookup(fs, &page, tree->root, tree->depth, va, page, 1);
 }
 
 int mufs_alloc_page(struct mufs_tree *tree, uint32_t *page,
@@ -57,14 +72,14 @@ int mufs_alloc_page(struct mufs_tree *tree, uint32_t *page,
 {
 	struct mufs *fs = tree->fs;
 
-	if (!tree->root && mufs_alloc_block(fs, &tree->root) < 0)
+	if (mufs_alloc_block(fs, page) < 0)
 		return -1;
 
-	return mufs_do_lookup(fs, page, tree->root, tree->depth, va, 1);
+	return mufs_map_page(tree, va, *page);
 }
 
 static int mufs_do_free_page(struct mufs *fs, uint32_t base,
-	uint8_t depth, uint32_t va)
+	uint8_t depth, uint32_t va, int free_page)
 {
 	struct flash_dev *dev = fs->dev;
 	char data[1 << fs->dev->log2_block_size];
@@ -75,7 +90,9 @@ static int mufs_do_free_page(struct mufs *fs, uint32_t base,
 		return -1;
 
 	if (!depth) {
-		mufs_free_block(fs, base);
+		if (free_page)
+			mufs_free_block(fs, base);
+
 		return 0;
 	}
 
@@ -85,7 +102,7 @@ static int mufs_do_free_page(struct mufs *fs, uint32_t base,
 
 	index = va & ((1 << (fs->log2_nentries * (depth - 1))) - 1);
 
-	if (mufs_do_free_page(fs, table[index], depth - 1, va) < 0)
+	if (mufs_do_free_page(fs, table[index], depth - 1, va, free_page) < 0)
 		return -1;
 
 	table[index] = 0;
@@ -104,9 +121,14 @@ static int mufs_do_free_page(struct mufs *fs, uint32_t base,
 	return mufs_free_block(fs, base);
 }
 
+void mufs_unmap_page(struct mufs_tree *tree, uint32_t va)
+{
+	mufs_do_free_page(tree->fs, tree->root, tree->depth, va, 0);
+}
+
 void mufs_free_page(struct mufs_tree *tree, uint32_t va)
 {
-	mufs_do_free_page(tree->fs, tree->root, tree->depth, va);
+	mufs_do_free_page(tree->fs, tree->root, tree->depth, va, 1);
 }
 
 int mufs_extend_tree(struct mufs_tree *tree, uint8_t depth)
diff --git a/source/fs/mufs/tree.h b/source/fs/mufs/tree.h
index 39c3602..bc3f0c6 100644
--- a/source/fs/mufs/tree.h
+++ b/source/fs/mufs/tree.h
@@ -2,6 +2,8 @@
 
 int mufs_lookup_page(struct mufs_tree *tree, uint32_t *page,
 	uint32_t va);
+int mufs_map_page(struct mufs_tree *tree, uint32_t va, uint32_t page);
+void mufs_unmap_page(struct mufs_tree *tree, uint32_t va);
 int mufs_alloc_page(struct mufs_tree *tree, uint32_t *page,
 	uint32_t va);
 void mufs_free_page(struct mufs_tree *tree, uint32_t va);