mufs: optimise memory footprint of find_dirent_size()

source/fs/mufs/dir.c

@@ -195,26 +195,24 @@ size_t find_dirent_size(struct mufs *fs, struct mufs_tree *tree,
 {
 	struct flash_dev *dev = fs->dev;
 	size_t block_size = 1 << dev->log2_block_size;
-	char data[block_size];
+	struct mufs_dentry entry;
-	struct mufs_dentry *entry;
 	uint32_t offset, len;
 
 	va = align(va, dev->log2_block_size);
 
-	if (mufs_tree_read(tree, data, va, 1 << dev->log2_block_size) == 0)
-		return 0;
-
 	for (offset = 0; offset < block_size; offset += len) {
-		entry = (struct mufs_dentry *)(data + offset);
+		len = sizeof entry;
-		len = sizeof *entry;
 
 		if (block_size - offset < len)
 			break;
 
-		if (!entry->type)
+		if (mufs_tree_read(tree, &entry, va + offset, sizeof entry) == 0)
+			break;
+
+		if (!entry.type)
 			break;
 
-		len += entry->path_len;
+		len += entry.path_len;
 
 		if (block_size - offset < len)
 			break;