The fsync vs I/O errors bug didn't have any performance impact in absence of failing disks, it was about what happened when you tried to fsync again after your storage stack reported a write error.

But for a OS that has a bad fsync, have a look at macOS - they even document that it doesn't commit data to stable storage and you should use some other system call to do it: https://developer.apple.com/library/archive/documentation/Sy...

(A web search now only finds iOS man pages, but the fsync caveat was the same in OS X/Darwin manpages before they were taken offline)