Better get the basics straight

I would hope that the operation "write data to file" gets less complex, not more. There is already a little dance of calls to be made (Ted writes about it). If we add logic on the application level to handle that some filesystems expect fsync on the directory, some on only the file and some manage without, it becomes even more so. In tens of thousands of applications.

But this is only vaguely related to the data ordering issue. In an interactive program or where performance is critical you may not want to wait until data is commited to disk. Latency kills.