For applications that expect NFS-like behavior with data flush on file close, and do not call fsync() on the file, it would be useful to provide a per-mountpoint tunable parameter and mount option that forces file data to be sync'd to the target, something like "llite.*.sync_on_close" and "-o sync_on_close", or similar. Better would be a per-directory flag that is inherited by files created therein, so that applications or administrators can set this for specific apps/users that need such semantics.

This would have a potentially large impact for workloads that are writing a large number of small files (e.g. tar), so it should default to "off", and only be enabled specifically for workloads that expect it.