Started adding some documentation

src/backing.c

@@ -377,3 +377,43 @@ result_t set_default_backing(const char* backing) {
 		return result;
 	}
 }
+
+result_t get_backing_parent(char** _parent, const char* backing) {
+	// Initialize the output parameters
+	*_parent = NULL;
+
+	// Get the backing path
+	char* path;
+	result_t result = get_backing_path(&path, backing);
+	if (result != success())
+		return result;
+
+	// Get the disk info
+	disk_info_t info;
+	result = get_disk_info(&info, path);
+	if (result != success()) {
+		free(path);
+		return result;
+	}
+
+	// If the disk is not backed, return success and a null parent
+	if (info.backing_path == NULL) {
+		free_disk_info(&info);
+		free(path);
+		return success();
+	}
+
+	// Get the backing identifier of the parent
+	char* parent = strdup(basename(info.backing_path));
+	if (parent == NULL) {
+		free_disk_info(&info);
+		free(path);
+		return failure("Failed to get the backing identifier of the parent.");
+	}
+
+	free_disk_info(&info);
+	free(path);
+
+	*_parent = parent;
+	return result;
+}