BOOL load_and_init_usnjrnl (ntfs_volume * vol);
Return TRUE on success or FALSE on error.
If $UsnJrnl is not present or in the process of being disabled, we set NVolUsnJrnlStamped and return success.
If the $UsnJrnl $DATA/$J attribute has a size equal to the lowest valid usn, i.e. transaction logging has only just been enabled or the journal has been stamped and nothing has been logged since, we also set NVolUsnJrnlStamped and return success.