Fault Injection Command.

FI service is registered with REQH by calling m0_fis_register(). The registration occurs during motr instance initialisation. The registration makes FIS service type be available globally in motr instance.

During motr finalisation FIS service type is unregistered by calling m0_fis_unregister().

Note: FIS related FOPs are not registered along with the service type (see fis_start() for the details of FOPs registration).