init: add an init_utimes helper

Add a simple helper to set timestamps with a kernel space file name and
switch the early init code over to it.

Signed-off-by: Christoph Hellwig <hch@lst.de>

fs/init.c

@@ -238,3 +238,16 @@ int __init init_rmdir(const char *pathname)
 {
 	return do_rmdir(AT_FDCWD, getname_kernel(pathname));
 }
+
+int __init init_utimes(char *filename, struct timespec64 *ts)
+{
+	struct path path;
+	int error;
+
+	error = kern_path(filename, 0, &path);
+	if (error)
+		return error;
+	error = vfs_utimes(&path, ts);
+	path_put(&path);
+	return error;
+}