O_SYNC behavior?

[Ray Van Dolson <rvandolson@xxxxxxxx>]

End-user question:

NFS client accessing an NFS export on an XFS based filesystem via
"sync" (O_SYNC) mode.

Will write confirmation be sent back from the NFS server when the data
is written to the xfs journal, or not until it is actually written to
disk (assuming in this case the journal is on a separate SSD device or
something similar)?

Thanks,
Ray