API option check is broken for AIO API

[Obihoernchen]

IOR with --with-aio has the following flags:

Module AIO

Flags
  --posix.odirect               Direct I/O Mode
  --posix.rangelocks            Use range locks (read locks for read ops)

Optional arguments
  --aio.max-pending=128         Max number of pending ops
  --aio.granularity=16          How frequent to submit pending IOs, submit every *granularity* elements

Using something like API = AIO --posix.odirect in config.ini throws the following (wrong) error message because the API flag does not start with --aio:

FATAL (src/util.c:164) Provided API option --posix.odirect appears to be no API supported version

Check: https://github.com/IO500/io500/blob/main/src/util.c#L147-L169

[adilger]

I does seem a bit strange that there is a "posix.odirect" option to the AIO backend, though I know that libaio is only handling the read/write calls and depends on POSIX for the rest.

I can understand the reason for the check, to avoid anlliwing options to a backend that will actually be ignored.

It might be better to handle this on the IOR side and change the AIO backend to accept "--aio.odirect". For that matter, does libaio make any sense without odirect?

[JulianKunkel]

From IOR side, this actually works, it is a sanity check in IO500.
$ ./src/ior -a aio --posix.odirect
works, for example...

[JulianKunkel]

Changed it to a warning:
#89

I think that is a good compromise and bears many advantage to test.