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

*** 375,384 ****
--- 375,387 ----
  void
  dnode_evict_dbufs(dnode_t *dn)
  {
          int progress;
          int pass = 0;
+         list_t evict_list;
+ 
+         dmu_buf_create_user_evict_list(&evict_list);
  
          do {
                  dmu_buf_impl_t *db, marker;
                  int evicting = FALSE;
  
*** 400,414 ****
                                  progress = TRUE;
                                  evicting = TRUE;
                                  mutex_exit(&db->db_mtx);
                          } else if (refcount_is_zero(&db->db_holds)) {
                                  progress = TRUE;
!                                 dbuf_clear(db); /* exits db_mtx for us */
                          } else {
                                  mutex_exit(&db->db_mtx);
                          }
! 
                  }
                  list_remove(&dn->dn_dbufs, &marker);
                  /*
                   * NB: we need to drop dn_dbufs_mtx between passes so
                   * that any DB_EVICTING dbufs can make progress.
--- 403,418 ----
                                  progress = TRUE;
                                  evicting = TRUE;
                                  mutex_exit(&db->db_mtx);
                          } else if (refcount_is_zero(&db->db_holds)) {
                                  progress = TRUE;
!                                 dbuf_clear(db, &evict_list); /* exits db_mtx */
                          } else {
                                  mutex_exit(&db->db_mtx);
                          }
!                         ASSERT(MUTEX_NOT_HELD(&db->db_mtx));
!                         dmu_buf_process_user_evicts(&evict_list);
                  }
                  list_remove(&dn->dn_dbufs, &marker);
                  /*
                   * NB: we need to drop dn_dbufs_mtx between passes so
                   * that any DB_EVICTING dbufs can make progress.
*** 424,437 ****
          } while (progress);
  
          rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
          if (dn->dn_bonus && refcount_is_zero(&dn->dn_bonus->db_holds)) {
                  mutex_enter(&dn->dn_bonus->db_mtx);
!                 dbuf_evict(dn->dn_bonus);
                  dn->dn_bonus = NULL;
          }
          rw_exit(&dn->dn_struct_rwlock);
  }
  
  static void
  dnode_undirty_dbufs(list_t *list)
  {
--- 428,442 ----
          } while (progress);
  
          rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
          if (dn->dn_bonus && refcount_is_zero(&dn->dn_bonus->db_holds)) {
                  mutex_enter(&dn->dn_bonus->db_mtx);
!                 dbuf_evict(dn->dn_bonus, &evict_list);
                  dn->dn_bonus = NULL;
          }
          rw_exit(&dn->dn_struct_rwlock);
+         dmu_buf_destroy_user_evict_list(&evict_list);
  }
  
  static void
  dnode_undirty_dbufs(list_t *list)
  {