From 2a62bd1f159a9de95b00178d37cedeb67f82697f Mon Sep 17 00:00:00 2001
From: "S.J.R. van Schaik" <stephan@whiteboxsystems.nl>
Date: Thu, 27 Jul 2017 17:06:07 +0200
Subject: [PATCH] mufs: properly free intermediate pages when empty in
 mufs_do_free_page()

---
 source/fs/mufs/tree.c | 44 +++++++++++++++++++++++++++++---------------
 1 file changed, 29 insertions(+), 15 deletions(-)

diff --git a/source/fs/mufs/tree.c b/source/fs/mufs/tree.c
index 040084a..2280bd8 100644
--- a/source/fs/mufs/tree.c
+++ b/source/fs/mufs/tree.c
@@ -109,47 +109,61 @@ int mufs_alloc_page(struct mufs_tree *tree, uint32_t *page,
 	return mufs_do_lookup(fs, page, tree->root, tree->depth, va, 0, 1);
 }
 
-static int mufs_do_free_page(struct mufs *fs, uint32_t base,
+static int mufs_do_free_page(struct mufs *fs, uint32_t *base,
 	uint8_t depth, uint32_t va, int free_page)
 {
 	struct flash_dev *dev = fs->dev;
-	uint32_t entry;
-	size_t index;
+	uint32_t offset, entry;
 
-	if (!base)
+	if (!base || *base == 0)
 		return -1;
 
 	if (depth == 0) {
-		if (free_page)
-			mufs_free_block(fs, base);
+		if (free_page) {
+			mufs_free_block(fs, *base);
+			*base = 0;
+		}
 
 		return 0;
 	}
 
-	base <<= dev->log2_block_size;
-	index = mufs_get_index(fs, va, depth);
-	base += index * sizeof entry;
+	offset = mufs_get_index(fs, va, depth) * sizeof entry;
+	offset += (*base << dev->log2_block_size);
+
+	if (flash_read(fs->dev, offset, &entry, sizeof entry) == 0)
+		return -1;
 
-	if (flash_read(fs->dev, base, &entry, sizeof entry) == 0)
+	if (mufs_do_free_page(fs, &entry, depth - 1, va, free_page) < 0)
 		return -1;
 
-	if (mufs_do_free_page(fs, entry, depth - 1, va, free_page) < 0)
+	if (entry != 0)
+		return 0;
+
+	if (flash_write0(fs->dev, offset, sizeof entry) == 0)
 		return -1;
 
-	if (flash_write0(fs->dev, base, sizeof entry) == 0)
+	if (flash_sync(fs->dev) == 0)
 		return -1;
 
-	return flash_sync(fs->dev);
+	if (!flash_is_erased(fs->dev, *base, 1))
+		return 0;
+
+	if (mufs_free_block(fs, *base) < 0)
+		return -1;
+
+	*base = 0;
+
+	return 0;
 }
 
 void mufs_unmap_page(struct mufs_tree *tree, uint32_t va)
 {
-	mufs_do_free_page(tree->fs, tree->root, tree->depth, va, 0);
+	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, 1);
+	mufs_do_free_page(tree->fs, &tree->root, tree->depth, va, 1);
 }
 
 int mufs_extend_tree(struct mufs_tree *tree, uint8_t depth)