3525 Persistent L2ARC

*** 1503,1514 ****
           */
          if (vd->vdev_aux) {
                  (void) vdev_validate_aux(vd);
                  if (vdev_readable(vd) && vdev_writeable(vd) &&
                      vd->vdev_aux == &spa->spa_l2cache &&
!                     !l2arc_vdev_present(vd))
!                         l2arc_add_vdev(spa, vd);
          } else {
                  (void) vdev_validate(vd, B_TRUE);
          }
  
          /*
--- 1503,1520 ----
           */
          if (vd->vdev_aux) {
                  (void) vdev_validate_aux(vd);
                  if (vdev_readable(vd) && vdev_writeable(vd) &&
                      vd->vdev_aux == &spa->spa_l2cache &&
!                     !l2arc_vdev_present(vd)) {
!                         /*
!                          * When reopening we can assume persistent L2ARC is
!                          * supported, since we've already opened the device
!                          * in the past and prepended an L2ARC uberblock.
!                          */
!                         l2arc_add_vdev(spa, vd, B_TRUE);
!                 }
          } else {
                  (void) vdev_validate(vd, B_TRUE);
          }
  
          /*