curzone reality check and teardown changes to use the RIGHT zone

*** 434,443 ****
--- 434,444 ----
                  resp->status = NFS3ERR_ACCES;
                  goto out1;
          }
  
          fhp = &args->what.dir;
+         ASSERT3P(curzone, ==, exi->exi_zone); /* exi is guaranteed non-NULL. */
          if (strcmp(args->what.name, "..") == 0 &&
              EQFID(&exi->exi_fid, FH3TOFIDP(fhp))) {
                  if ((exi->exi_export.ex_flags & EX_NOHIDE) &&
                      ((dvp->v_flag & VROOT) || VN_IS_CURZONEROOT(dvp))) {
                          /*
*** 1323,1332 ****
--- 1324,1334 ----
          if (vp == NULL) {
                  error = ESTALE;
                  goto err;
          }
  
+         ASSERT3P(curzone, ==, exi->exi_zone); /* exi is guaranteed non-NULL. */
          ns = zone_getspecific(rfs3_zone_key, curzone);
          if (is_system_labeled()) {
                  bslabel_t *clabel = req->rq_label;
  
                  ASSERT(clabel != NULL);
*** 4123,4132 ****
--- 4125,4135 ----
          if (vp == NULL) {
                  error = ESTALE;
                  goto out;
          }
  
+         ASSERT3P(curzone, ==, exi->exi_zone); /* exi is guaranteed non-NULL. */
          ns = zone_getspecific(rfs3_zone_key, curzone);
          bva.va_mask = AT_ALL;
          error = VOP_GETATTR(vp, &bva, 0, cr, NULL);
  
          /*