sr_mp
mp = srp->sr_mp;
srp->sr_mp = NULL;
srp->sr_mpp = &(srp->sr_mp);
ASSERT(srp->sr_mp == NULL);
ASSERT(srp->sr_mpp == &(srp->sr_mp));
prefetch_read_many(srp->sr_mp);
if (srp->sr_mp != NULL) {
mp = srp->sr_mp;
srp->sr_mp = NULL;
srp->sr_mpp = &(srp->sr_mp);
srp->sr_mpp = &(srp->sr_mp);