fsync() after open() is an elaborate no-op
I have spent the last couple of years of my life trying to make sense of fsync() and bringing OpenZFS up to code. I’ve read a lot of horror stories about this apparently-simple syscall in that time, usually written by people who tried very hard to get it right but ended up losing data in different ways. I hesitate to say I enjoy reading these things, because they usually start with some catastrophic data loss situation and that’s just miserably unfair. At least, I think they’re important reads, and I’m always glad to see another story of fsync() done right, or done wrong.