Directories created by boost::filesystem::create_directories() not immediately accessible?

I am using boost::filesystem::create_directories() to create new directories. When I try to access these directories shortly after creation, I get an error saying: no such directory. But if I sleep for a wh开发者_开发技巧ile after creating directories everything is fine (I do not get the error). Also, I tried using fsync() and sync() after creating directories but it made no difference. I am testing it on ext4 and xfs file systems and my boost version is boost 1.44

My questions are

1. Does boost::create_directories() create directories instantly? Or is it possible that something is wrong there?
2. Also, are sync() and fsync() guaranteed to flush everything to disc on ext4/xfs?