3006 VERIFY[S,U,P] and ASSERT[S,U,P] frequently check if first argument is zero

*** 590,602 ****
          if (vd->vdev_mg != NULL) {
                  vdev_metaslab_fini(vd);
                  metaslab_group_destroy(vd->vdev_mg);
          }
  
!         ASSERT3U(vd->vdev_stat.vs_space, ==, 0);
!         ASSERT3U(vd->vdev_stat.vs_dspace, ==, 0);
!         ASSERT3U(vd->vdev_stat.vs_alloc, ==, 0);
  
          /*
           * Remove this vdev from its parent's child list.
           */
          vdev_remove_child(vd->vdev_parent, vd);
--- 590,602 ----
          if (vd->vdev_mg != NULL) {
                  vdev_metaslab_fini(vd);
                  metaslab_group_destroy(vd->vdev_mg);
          }
  
!         ASSERT0(vd->vdev_stat.vs_space);
!         ASSERT0(vd->vdev_stat.vs_dspace);
!         ASSERT0(vd->vdev_stat.vs_alloc);
  
          /*
           * Remove this vdev from its parent's child list.
           */
          vdev_remove_child(vd->vdev_parent, vd);
*** 1803,1813 ****
          tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
  
          if (vd->vdev_detached) {
                  if (smo->smo_object != 0) {
                          int err = dmu_object_free(mos, smo->smo_object, tx);
!                         ASSERT3U(err, ==, 0);
                          smo->smo_object = 0;
                  }
                  dmu_tx_commit(tx);
                  return;
          }
--- 1803,1813 ----
          tx = dmu_tx_create_assigned(spa->spa_dsl_pool, txg);
  
          if (vd->vdev_detached) {
                  if (smo->smo_object != 0) {
                          int err = dmu_object_free(mos, smo->smo_object, tx);
!                         ASSERT0(err);
                          smo->smo_object = 0;
                  }
                  dmu_tx_commit(tx);
                  return;
          }
*** 2003,2013 ****
          dmu_tx_t *tx;
  
          tx = dmu_tx_create_assigned(spa_get_dsl(spa), txg);
  
          if (vd->vdev_dtl_smo.smo_object) {
!                 ASSERT3U(vd->vdev_dtl_smo.smo_alloc, ==, 0);
                  (void) dmu_object_free(mos, vd->vdev_dtl_smo.smo_object, tx);
                  vd->vdev_dtl_smo.smo_object = 0;
          }
  
          if (vd->vdev_ms != NULL) {
--- 2003,2013 ----
          dmu_tx_t *tx;
  
          tx = dmu_tx_create_assigned(spa_get_dsl(spa), txg);
  
          if (vd->vdev_dtl_smo.smo_object) {
!                 ASSERT0(vd->vdev_dtl_smo.smo_alloc);
                  (void) dmu_object_free(mos, vd->vdev_dtl_smo.smo_object, tx);
                  vd->vdev_dtl_smo.smo_object = 0;
          }
  
          if (vd->vdev_ms != NULL) {
*** 2015,2025 ****
                          metaslab_t *msp = vd->vdev_ms[m];
  
                          if (msp == NULL || msp->ms_smo.smo_object == 0)
                                  continue;
  
!                         ASSERT3U(msp->ms_smo.smo_alloc, ==, 0);
                          (void) dmu_object_free(mos, msp->ms_smo.smo_object, tx);
                          msp->ms_smo.smo_object = 0;
                  }
          }
  
--- 2015,2025 ----
                          metaslab_t *msp = vd->vdev_ms[m];
  
                          if (msp == NULL || msp->ms_smo.smo_object == 0)
                                  continue;
  
!                         ASSERT0(msp->ms_smo.smo_alloc);
                          (void) dmu_object_free(mos, msp->ms_smo.smo_object, tx);
                          msp->ms_smo.smo_object = 0;
                  }
          }
  
*** 2293,2303 ****
                                          return (spa_vdev_state_exit(spa,
                                              vd, error));
                                  (void) spa_vdev_state_exit(spa, vd, 0);
                                  goto top;
                          }
!                         ASSERT3U(tvd->vdev_stat.vs_alloc, ==, 0);
                  }
  
                  /*
                   * Offline this device and reopen its top-level vdev.
                   * If the top-level vdev is a log device then just offline
--- 2293,2303 ----
                                          return (spa_vdev_state_exit(spa,
                                              vd, error));
                                  (void) spa_vdev_state_exit(spa, vd, 0);
                                  goto top;
                          }
!                         ASSERT0(tvd->vdev_stat.vs_alloc);
                  }
  
                  /*
                   * Offline this device and reopen its top-level vdev.
                   * If the top-level vdev is a log device then just offline