3888 zfs recv -F should destroy any snapshots created since the incremental source
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Peng Dai <peng.dai@delphix.com>

*** 1531,1561 ****
          *usedobjsp = ds->ds_phys->ds_bp.blk_fill;
          *availobjsp = DN_MAX_OBJECT - *usedobjsp;
  }
  
  boolean_t
! dsl_dataset_modified_since_lastsnap(dsl_dataset_t *ds)
  {
          dsl_pool_t *dp = ds->ds_dir->dd_pool;
  
          ASSERT(dsl_pool_config_held(dp));
!         if (ds->ds_prev == NULL)
                  return (B_FALSE);
          if (ds->ds_phys->ds_bp.blk_birth >
!             ds->ds_prev->ds_phys->ds_creation_txg) {
!                 objset_t *os, *os_prev;
                  /*
                   * It may be that only the ZIL differs, because it was
                   * reset in the head.  Don't count that as being
                   * modified.
                   */
                  if (dmu_objset_from_ds(ds, &os) != 0)
                          return (B_TRUE);
!                 if (dmu_objset_from_ds(ds->ds_prev, &os_prev) != 0)
                          return (B_TRUE);
                  return (bcmp(&os->os_phys->os_meta_dnode,
!                     &os_prev->os_phys->os_meta_dnode,
                      sizeof (os->os_phys->os_meta_dnode)) != 0);
          }
          return (B_FALSE);
  }
  
--- 1531,1561 ----
          *usedobjsp = ds->ds_phys->ds_bp.blk_fill;
          *availobjsp = DN_MAX_OBJECT - *usedobjsp;
  }
  
  boolean_t
! dsl_dataset_modified_since_snap(dsl_dataset_t *ds, dsl_dataset_t *snap)
  {
          dsl_pool_t *dp = ds->ds_dir->dd_pool;
  
          ASSERT(dsl_pool_config_held(dp));
!         if (snap == NULL)
                  return (B_FALSE);
          if (ds->ds_phys->ds_bp.blk_birth >
!             snap->ds_phys->ds_creation_txg) {
!                 objset_t *os, *os_snap;
                  /*
                   * It may be that only the ZIL differs, because it was
                   * reset in the head.  Don't count that as being
                   * modified.
                   */
                  if (dmu_objset_from_ds(ds, &os) != 0)
                          return (B_TRUE);
!                 if (dmu_objset_from_ds(snap, &os_snap) != 0)
                          return (B_TRUE);
                  return (bcmp(&os->os_phys->os_meta_dnode,
!                     &os_snap->os_phys->os_meta_dnode,
                      sizeof (os->os_phys->os_meta_dnode)) != 0);
          }
          return (B_FALSE);
  }
  
*** 2354,2380 ****
          /* they should both be heads */
          if (dsl_dataset_is_snapshot(clone) ||
              dsl_dataset_is_snapshot(origin_head))
                  return (SET_ERROR(EINVAL));
  
!         /* the branch point should be just before them */
!         if (clone->ds_prev != origin_head->ds_prev)
                  return (SET_ERROR(EINVAL));
  
          /* clone should be the clone (unless they are unrelated) */
          if (clone->ds_prev != NULL &&
              clone->ds_prev != clone->ds_dir->dd_pool->dp_origin_snap &&
!             origin_head->ds_object !=
!             clone->ds_prev->ds_phys->ds_next_snap_obj)
                  return (SET_ERROR(EINVAL));
  
          /* the clone should be a child of the origin */
          if (clone->ds_dir->dd_parent != origin_head->ds_dir)
                  return (SET_ERROR(EINVAL));
  
          /* origin_head shouldn't be modified unless 'force' */
!         if (!force && dsl_dataset_modified_since_lastsnap(origin_head))
                  return (SET_ERROR(ETXTBSY));
  
          /* origin_head should have no long holds (e.g. is not mounted) */
          if (dsl_dataset_handoff_check(origin_head, owner, tx))
                  return (SET_ERROR(EBUSY));
--- 2354,2380 ----
          /* they should both be heads */
          if (dsl_dataset_is_snapshot(clone) ||
              dsl_dataset_is_snapshot(origin_head))
                  return (SET_ERROR(EINVAL));
  
!         /* if we are not forcing, the branch point should be just before them */
!         if (!force && clone->ds_prev != origin_head->ds_prev)
                  return (SET_ERROR(EINVAL));
  
          /* clone should be the clone (unless they are unrelated) */
          if (clone->ds_prev != NULL &&
              clone->ds_prev != clone->ds_dir->dd_pool->dp_origin_snap &&
!             origin_head->ds_dir != clone->ds_prev->ds_dir)
                  return (SET_ERROR(EINVAL));
  
          /* the clone should be a child of the origin */
          if (clone->ds_dir->dd_parent != origin_head->ds_dir)
                  return (SET_ERROR(EINVAL));
  
          /* origin_head shouldn't be modified unless 'force' */
!         if (!force &&
!             dsl_dataset_modified_since_snap(origin_head, origin_head->ds_prev))
                  return (SET_ERROR(ETXTBSY));
  
          /* origin_head should have no long holds (e.g. is not mounted) */
          if (dsl_dataset_handoff_check(origin_head, owner, tx))
                  return (SET_ERROR(EBUSY));
*** 2407,2416 ****
--- 2407,2417 ----
          int64_t unused_refres_delta;
  
          ASSERT(clone->ds_reserved == 0);
          ASSERT(origin_head->ds_quota == 0 ||
              clone->ds_phys->ds_unique_bytes <= origin_head->ds_quota);
+         ASSERT3P(clone->ds_prev, ==, origin_head->ds_prev);
  
          dmu_buf_will_dirty(clone->ds_dbuf, tx);
          dmu_buf_will_dirty(origin_head->ds_dbuf, tx);
  
          if (clone->ds_objset != NULL) {