+
+
+/*
+ * Return (in *usedp) the amount of space written in new that is not
+ * present in oldsnap. New may be a snapshot or the head. Old must be
+ * a snapshot before new, in new's filesystem (or its origin). If not then
+ * fail and return EINVAL.
+ *
+ * The written space is calculated by considering two components: First, we
+ * ignore any freed space, and calculate the written as new's used space
+ * minus old's used space. Next, we add in the amount of space that was freed
+ * between the two snapshots, thus reducing new's used space relative to old's.
+ * Specifically, this is the space that was born before old->ds_creation_txg,
+ * and freed before new (ie. on new's deadlist or a previous deadlist).
+ *
+ * space freed [---------------------]
+ * snapshots ---O-------O--------O-------O------
+ * oldsnap new
+ */
+int
+dsl_dataset_space_written(dsl_dataset_t *oldsnap, dsl_dataset_t *new,
+ uint64_t *usedp, uint64_t *compp, uint64_t *uncompp)
+{
+ int err = 0;
+ uint64_t snapobj;
+ dsl_pool_t *dp = new->ds_dir->dd_pool;
+
+ *usedp = 0;
+ *usedp += new->ds_phys->ds_referenced_bytes;
+ *usedp -= oldsnap->ds_phys->ds_referenced_bytes;
+
+ *compp = 0;
+ *compp += new->ds_phys->ds_compressed_bytes;
+ *compp -= oldsnap->ds_phys->ds_compressed_bytes;
+
+ *uncompp = 0;
+ *uncompp += new->ds_phys->ds_uncompressed_bytes;
+ *uncompp -= oldsnap->ds_phys->ds_uncompressed_bytes;
+
+ rw_enter(&dp->dp_config_rwlock, RW_READER);
+ snapobj = new->ds_object;
+ while (snapobj != oldsnap->ds_object) {
+ dsl_dataset_t *snap;
+ uint64_t used, comp, uncomp;
+
+ if (snapobj == new->ds_object) {
+ snap = new;
+ } else {
+ err = dsl_dataset_hold_obj(dp, snapobj, FTAG, &snap);
+ if (err != 0)
+ break;
+ }
+
+ if (snap->ds_phys->ds_prev_snap_txg ==
+ oldsnap->ds_phys->ds_creation_txg) {
+ /*
+ * The blocks in the deadlist can not be born after
+ * ds_prev_snap_txg, so get the whole deadlist space,
+ * which is more efficient (especially for old-format
+ * deadlists). Unfortunately the deadlist code
+ * doesn't have enough information to make this
+ * optimization itself.
+ */
+ dsl_deadlist_space(&snap->ds_deadlist,
+ &used, &comp, &uncomp);
+ } else {
+ dsl_deadlist_space_range(&snap->ds_deadlist,
+ 0, oldsnap->ds_phys->ds_creation_txg,
+ &used, &comp, &uncomp);
+ }
+ *usedp += used;
+ *compp += comp;
+ *uncompp += uncomp;
+
+ /*
+ * If we get to the beginning of the chain of snapshots
+ * (ds_prev_snap_obj == 0) before oldsnap, then oldsnap
+ * was not a snapshot of/before new.
+ */
+ snapobj = snap->ds_phys->ds_prev_snap_obj;
+ if (snap != new)
+ dsl_dataset_rele(snap, FTAG);
+ if (snapobj == 0) {
+ err = EINVAL;
+ break;
+ }
+
+ }
+ rw_exit(&dp->dp_config_rwlock);
+ return (err);
+}
+
+/*
+ * Return (in *usedp) the amount of space that will be reclaimed if firstsnap,
+ * lastsnap, and all snapshots in between are deleted.
+ *
+ * blocks that would be freed [---------------------------]
+ * snapshots ---O-------O--------O-------O--------O
+ * firstsnap lastsnap
+ *
+ * This is the set of blocks that were born after the snap before firstsnap,
+ * (birth > firstsnap->prev_snap_txg) and died before the snap after the
+ * last snap (ie, is on lastsnap->ds_next->ds_deadlist or an earlier deadlist).
+ * We calculate this by iterating over the relevant deadlists (from the snap
+ * after lastsnap, backward to the snap after firstsnap), summing up the
+ * space on the deadlist that was born after the snap before firstsnap.
+ */
+int
+dsl_dataset_space_wouldfree(dsl_dataset_t *firstsnap,
+ dsl_dataset_t *lastsnap,
+ uint64_t *usedp, uint64_t *compp, uint64_t *uncompp)
+{
+ int err = 0;
+ uint64_t snapobj;
+ dsl_pool_t *dp = firstsnap->ds_dir->dd_pool;
+
+ ASSERT(dsl_dataset_is_snapshot(firstsnap));
+ ASSERT(dsl_dataset_is_snapshot(lastsnap));
+
+ /*
+ * Check that the snapshots are in the same dsl_dir, and firstsnap
+ * is before lastsnap.
+ */
+ if (firstsnap->ds_dir != lastsnap->ds_dir ||
+ firstsnap->ds_phys->ds_creation_txg >
+ lastsnap->ds_phys->ds_creation_txg)
+ return (EINVAL);
+
+ *usedp = *compp = *uncompp = 0;
+
+ rw_enter(&dp->dp_config_rwlock, RW_READER);
+ snapobj = lastsnap->ds_phys->ds_next_snap_obj;
+ while (snapobj != firstsnap->ds_object) {
+ dsl_dataset_t *ds;
+ uint64_t used, comp, uncomp;
+
+ err = dsl_dataset_hold_obj(dp, snapobj, FTAG, &ds);
+ if (err != 0)
+ break;
+
+ dsl_deadlist_space_range(&ds->ds_deadlist,
+ firstsnap->ds_phys->ds_prev_snap_txg, UINT64_MAX,
+ &used, &comp, &uncomp);
+ *usedp += used;
+ *compp += comp;
+ *uncompp += uncomp;
+
+ snapobj = ds->ds_phys->ds_prev_snap_obj;
+ ASSERT3U(snapobj, !=, 0);
+ dsl_dataset_rele(ds, FTAG);
+ }
+ rw_exit(&dp->dp_config_rwlock);
+ return (err);
+}
+
+#if defined(_KERNEL) && defined(HAVE_SPL)
+EXPORT_SYMBOL(dmu_snapshots_destroy_nvl);
+EXPORT_SYMBOL(dsl_dataset_hold);
+EXPORT_SYMBOL(dsl_dataset_hold_obj);
+EXPORT_SYMBOL(dsl_dataset_own);
+EXPORT_SYMBOL(dsl_dataset_own_obj);
+EXPORT_SYMBOL(dsl_dataset_name);
+EXPORT_SYMBOL(dsl_dataset_rele);
+EXPORT_SYMBOL(dsl_dataset_disown);
+EXPORT_SYMBOL(dsl_dataset_drop_ref);
+EXPORT_SYMBOL(dsl_dataset_tryown);
+EXPORT_SYMBOL(dsl_dataset_make_exclusive);
+EXPORT_SYMBOL(dsl_dataset_create_sync);
+EXPORT_SYMBOL(dsl_dataset_create_sync_dd);
+EXPORT_SYMBOL(dsl_dataset_destroy);
+EXPORT_SYMBOL(dsl_dataset_destroy_check);
+EXPORT_SYMBOL(dsl_dataset_destroy_sync);
+EXPORT_SYMBOL(dsl_dataset_snapshot_check);
+EXPORT_SYMBOL(dsl_dataset_snapshot_sync);
+EXPORT_SYMBOL(dsl_dataset_rename);
+EXPORT_SYMBOL(dsl_dataset_promote);
+EXPORT_SYMBOL(dsl_dataset_clone_swap);
+EXPORT_SYMBOL(dsl_dataset_user_hold);
+EXPORT_SYMBOL(dsl_dataset_user_release);
+EXPORT_SYMBOL(dsl_dataset_user_release_tmp);
+EXPORT_SYMBOL(dsl_dataset_get_holds);
+EXPORT_SYMBOL(dsl_dataset_get_blkptr);
+EXPORT_SYMBOL(dsl_dataset_set_blkptr);
+EXPORT_SYMBOL(dsl_dataset_get_spa);
+EXPORT_SYMBOL(dsl_dataset_modified_since_lastsnap);
+EXPORT_SYMBOL(dsl_dataset_space_written);
+EXPORT_SYMBOL(dsl_dataset_space_wouldfree);
+EXPORT_SYMBOL(dsl_dataset_sync);
+EXPORT_SYMBOL(dsl_dataset_block_born);
+EXPORT_SYMBOL(dsl_dataset_block_kill);
+EXPORT_SYMBOL(dsl_dataset_block_freeable);
+EXPORT_SYMBOL(dsl_dataset_prev_snap_txg);
+EXPORT_SYMBOL(dsl_dataset_dirty);
+EXPORT_SYMBOL(dsl_dataset_stats);
+EXPORT_SYMBOL(dsl_dataset_fast_stat);
+EXPORT_SYMBOL(dsl_dataset_space);
+EXPORT_SYMBOL(dsl_dataset_fsid_guid);
+EXPORT_SYMBOL(dsl_dsobj_to_dsname);
+EXPORT_SYMBOL(dsl_dataset_check_quota);
+EXPORT_SYMBOL(dsl_dataset_set_quota);
+EXPORT_SYMBOL(dsl_dataset_set_quota_sync);
+EXPORT_SYMBOL(dsl_dataset_set_reservation);
+EXPORT_SYMBOL(dsl_destroy_inconsistent);
+#endif