`IOResult` implies we have a state machine that needs to be polled to
`Completion`, which is not the case here. We are just emitting the IO
operation in this case. This led us to never reaching the
`IOResult::Done` branch that actually fsynced the logical log in
`Checkpoint`.
I also sprinkled some
```rust
if c.is_completed() {
Ok(TransitionResult::Continue)
} else {
Ok(TransitionResult::Io(IOCompletions::Single(c)))
}
```
just to be more efficient with sync IO, but it is not strictly necessary
here.
Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>
Closes#3549
33e727ce8f