Re-introduce pfl_fault_register() so I can have fault points before any I/O.
Re-introduce pfl_fault_register() so I can have fault points before any I/O.

pscedu/slash2-stable,pscedu/slash2-stable,pscedu/pfl,pscedu/pfl,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/pfl,pscedu/pfl,pscedu/slash2-stable