[altfredd]

The "data" setting of ext filesystems isn't replacement for fsync().

[Dylan16807]

It's not a replacement but it can give you some guarantees.

Also fsync is a terrible API that should be replaced, but that's mostly a different topic.

[the8472]

At least on linux you can use io_uring to make fsync asynchronous. And you can initiate some preparatory flushing with sync_file_range and only do the final commit with fsync to cut down the latency.