+
+taskq_t *
+dsl_pool_vnrele_taskq(dsl_pool_t *dp)
+{
+ return (dp->dp_vnrele_taskq);
+}
+
+/*
+ * Walk through the pool-wide zap object of temporary snapshot user holds
+ * and release them.
+ */
+void
+dsl_pool_clean_tmp_userrefs(dsl_pool_t *dp)
+{
+ zap_attribute_t za;
+ zap_cursor_t zc;
+ objset_t *mos = dp->dp_meta_objset;
+ uint64_t zapobj = dp->dp_tmp_userrefs_obj;
+
+ if (zapobj == 0)
+ return;
+ ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
+
+ for (zap_cursor_init(&zc, mos, zapobj);
+ zap_cursor_retrieve(&zc, &za) == 0;
+ zap_cursor_advance(&zc)) {
+ char *htag;
+ uint64_t dsobj;
+
+ htag = strchr(za.za_name, '-');
+ *htag = '\0';
+ ++htag;
+ dsobj = strtonum(za.za_name, NULL);
+ (void) dsl_dataset_user_release_tmp(dp, dsobj, htag, B_FALSE);
+ }
+ zap_cursor_fini(&zc);
+}
+
+/*
+ * Create the pool-wide zap object for storing temporary snapshot holds.
+ */
+void
+dsl_pool_user_hold_create_obj(dsl_pool_t *dp, dmu_tx_t *tx)
+{
+ objset_t *mos = dp->dp_meta_objset;
+
+ ASSERT(dp->dp_tmp_userrefs_obj == 0);
+ ASSERT(dmu_tx_is_syncing(tx));
+
+ dp->dp_tmp_userrefs_obj = zap_create(mos, DMU_OT_USERREFS,
+ DMU_OT_NONE, 0, tx);
+
+ VERIFY(zap_add(mos, DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_TMP_USERREFS,
+ sizeof (uint64_t), 1, &dp->dp_tmp_userrefs_obj, tx) == 0);
+}
+
+static int
+dsl_pool_user_hold_rele_impl(dsl_pool_t *dp, uint64_t dsobj,
+ const char *tag, uint64_t *now, dmu_tx_t *tx, boolean_t holding)
+{
+ objset_t *mos = dp->dp_meta_objset;
+ uint64_t zapobj = dp->dp_tmp_userrefs_obj;
+ char *name;
+ int error;
+
+ ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
+ ASSERT(dmu_tx_is_syncing(tx));
+
+ /*
+ * If the pool was created prior to SPA_VERSION_USERREFS, the
+ * zap object for temporary holds might not exist yet.
+ */
+ if (zapobj == 0) {
+ if (holding) {
+ dsl_pool_user_hold_create_obj(dp, tx);
+ zapobj = dp->dp_tmp_userrefs_obj;
+ } else {
+ return (ENOENT);
+ }
+ }
+
+ name = kmem_asprintf("%llx-%s", (u_longlong_t)dsobj, tag);
+ if (holding)
+ error = zap_add(mos, zapobj, name, 8, 1, now, tx);
+ else
+ error = zap_remove(mos, zapobj, name, tx);
+ strfree(name);
+
+ return (error);
+}
+
+/*
+ * Add a temporary hold for the given dataset object and tag.
+ */
+int
+dsl_pool_user_hold(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
+ uint64_t *now, dmu_tx_t *tx)
+{
+ return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, now, tx, B_TRUE));
+}
+
+/*
+ * Release a temporary hold for the given dataset object and tag.
+ */
+int
+dsl_pool_user_release(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
+ dmu_tx_t *tx)
+{
+ return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, NULL,
+ tx, B_FALSE));
+}