unlockrange
void unlockrange(int plexno, struct rangelock *);
unlockrange(rqg->plexno, rqg->lock); /* yes, free it */
unlockrange(rqg->plexno, rqg->lock); /* yes, free it */
unlockrange(rqg->plexno, rqg->lock); /* yes, free it */
unlockrange(sd->plexno, lock); /* give it back */
unlockrange(plexno, lock);