mufs: reduce memory footprint of mufs_do_free_page()

source/fs/mufs/tree.c

@@ -97,62 +97,47 @@ 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;
-	char data[1 << fs->dev->log2_block_size];
-	uint32_t *table = (uint32_t *)data;
+	uint32_t entry;
 	size_t index;
 
-	if (!base || *base == 0)
+	if (base == 0)
 		return -1;
 
 	if (!depth) {
-		if (free_page) {
-			mufs_free_block(fs, *base);
-			*base = 0;
-		}
+		if (free_page)
+			mufs_free_block(fs, base);
 
 		return 0;
 	}
 
-	if (flash_read(fs->dev, *base << dev->log2_block_size, data,
-		sizeof data) == 0)
-		return -1;
-
 	index = va & ((1 << (fs->log2_nentries * (depth - 1))) - 1);
 
-	if (mufs_do_free_page(fs, table + index, depth - 1, va, free_page) < 0)
+	if (flash_read(fs->dev, (base << dev->log2_block_size) + index *
+		sizeof entry, &entry, sizeof entry) == 0)
 		return -1;
 
-	for (index = 0; index < (UINT32_C(1) << fs->log2_nentries); ++index) {
-		if (!table[index])
-			continue;
-
-		if (flash_write(dev, *base << dev->log2_block_size, data,
-			sizeof data) == 0)
-			return -1;
-
-		return 0;
-	}
-
-	if (mufs_free_block(fs, *base) < 0)
+	if (mufs_do_free_page(fs, entry, depth - 1, va, free_page) < 0)
 		return -1;
 
-	*base = 0;
+	if (flash_write0(fs->dev, (base << dev->log2_block_size) + index *
+		sizeof entry, sizeof entry) == 0)
+		return -1;
 
-	return 0;
+	return flash_sync(fs->dev);
 }
 
 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)