3752 want more verifiable dbuf user eviction
Submitted by:   Justin Gibbs <justing@spectralogic.com>
Submitted by:   Will Andrews <willa@spectralogic.com>

*** 456,467 ****
          if (dn->dn_dirtyctx_firstset != NULL) {
                  kmem_free(dn->dn_dirtyctx_firstset, 1);
                  dn->dn_dirtyctx_firstset = NULL;
          }
          if (dn->dn_bonus != NULL) {
                  mutex_enter(&dn->dn_bonus->db_mtx);
!                 dbuf_evict(dn->dn_bonus);
                  dn->dn_bonus = NULL;
          }
          dn->dn_zio = NULL;
  
          dn->dn_have_spill = B_FALSE;
--- 456,471 ----
          if (dn->dn_dirtyctx_firstset != NULL) {
                  kmem_free(dn->dn_dirtyctx_firstset, 1);
                  dn->dn_dirtyctx_firstset = NULL;
          }
          if (dn->dn_bonus != NULL) {
+                 list_t evict_list;
+ 
+                 dmu_buf_create_user_evict_list(&evict_list);
                  mutex_enter(&dn->dn_bonus->db_mtx);
!                 dbuf_evict(dn->dn_bonus, &evict_list);
!                 dmu_buf_destroy_user_evict_list(&evict_list);
                  dn->dn_bonus = NULL;
          }
          dn->dn_zio = NULL;
  
          dn->dn_have_spill = B_FALSE;
*** 955,973 ****
          DNODE_VERIFY(dn);
          return (dn);
  }
  
  static void
! dnode_buf_pageout(dmu_buf_t *db, void *arg)
  {
!         dnode_children_t *children_dnodes = arg;
          int i;
-         int epb = db->db_size >> DNODE_SHIFT;
- 
-         ASSERT(epb == children_dnodes->dnc_count);
  
!         for (i = 0; i < epb; i++) {
                  dnode_handle_t *dnh = &children_dnodes->dnc_children[i];
                  dnode_t *dn;
  
                  /*
                   * The dnode handle lock guards against the dnode moving to
--- 959,974 ----
          DNODE_VERIFY(dn);
          return (dn);
  }
  
  static void
! dnode_buf_pageout(dmu_buf_user_t *dbu)
  {
!         dnode_children_t *children_dnodes = (dnode_children_t *)dbu;
          int i;
  
!         for (i = 0; i < children_dnodes->dnc_count; i++) {
                  dnode_handle_t *dnh = &children_dnodes->dnc_children[i];
                  dnode_t *dn;
  
                  /*
                   * The dnode handle lock guards against the dnode moving to
*** 993,1003 ****
                  dnode_destroy(dn); /* implicit zrl_remove() */
                  zrl_destroy(&dnh->dnh_zrlock);
                  dnh->dnh_dnode = NULL;
          }
          kmem_free(children_dnodes, sizeof (dnode_children_t) +
!             (epb - 1) * sizeof (dnode_handle_t));
  }
  
  /*
   * errors:
   * EINVAL - invalid object number.
--- 994,1004 ----
                  dnode_destroy(dn); /* implicit zrl_remove() */
                  zrl_destroy(&dnh->dnh_zrlock);
                  dnh->dnh_dnode = NULL;
          }
          kmem_free(children_dnodes, sizeof (dnode_children_t) +
!             (children_dnodes->dnc_count - 1) * sizeof (dnode_handle_t));
  }
  
  /*
   * errors:
   * EINVAL - invalid object number.
*** 1073,1083 ****
          epb = db->db.db_size >> DNODE_SHIFT;
  
          idx = object & (epb-1);
  
          ASSERT(DB_DNODE(db)->dn_type == DMU_OT_DNODE);
!         children_dnodes = dmu_buf_get_user(&db->db);
          if (children_dnodes == NULL) {
                  int i;
                  dnode_children_t *winner;
                  children_dnodes = kmem_alloc(sizeof (dnode_children_t) +
                      (epb - 1) * sizeof (dnode_handle_t), KM_SLEEP);
--- 1074,1084 ----
          epb = db->db.db_size >> DNODE_SHIFT;
  
          idx = object & (epb-1);
  
          ASSERT(DB_DNODE(db)->dn_type == DMU_OT_DNODE);
!         children_dnodes = (dnode_children_t *)dmu_buf_get_user(&db->db);
          if (children_dnodes == NULL) {
                  int i;
                  dnode_children_t *winner;
                  children_dnodes = kmem_alloc(sizeof (dnode_children_t) +
                      (epb - 1) * sizeof (dnode_handle_t), KM_SLEEP);
*** 1085,1096 ****
                  dnh = &children_dnodes->dnc_children[0];
                  for (i = 0; i < epb; i++) {
                          zrl_init(&dnh[i].dnh_zrlock);
                          dnh[i].dnh_dnode = NULL;
                  }
!                 if (winner = dmu_buf_set_user(&db->db, children_dnodes, NULL,
!                     dnode_buf_pageout)) {
                          kmem_free(children_dnodes, sizeof (dnode_children_t) +
                              (epb - 1) * sizeof (dnode_handle_t));
                          children_dnodes = winner;
                  }
          }
--- 1086,1100 ----
                  dnh = &children_dnodes->dnc_children[0];
                  for (i = 0; i < epb; i++) {
                          zrl_init(&dnh[i].dnh_zrlock);
                          dnh[i].dnh_dnode = NULL;
                  }
!                 dmu_buf_init_user(&children_dnodes->db_evict,
!                     dnode_buf_pageout);
!                 winner = (dnode_children_t *)
!                     dmu_buf_set_user(&db->db, &children_dnodes->db_evict);
!                 if (winner) {
                          kmem_free(children_dnodes, sizeof (dnode_children_t) +
                              (epb - 1) * sizeof (dnode_handle_t));
                          children_dnodes = winner;
                  }
          }