ZIL claiming should not start user accounting

Currently, ZIL claiming dirties objsets which causes
dsl_pool_sync() to attempt to perform user accounting on
them. This causes problems for encrypted datasets that were
raw received before the system went offline since they
cannot perform user accounting until they have their keys
loaded. This triggers an ASSERT in zio_encrypt(). Since
encryption was added, the code now depends on the fact that
data should only be written when objsets are owned. This
patch adds a check in dmu_objset_do_userquota_updates()
to ensure that useraccounting is only done when the objsets
are actually owned.

Fixes: openzfs#6916

Signed-off-by: Tom Caputi <tcaputi@datto.com>

module/zfs/dmu_objset.c

@@ -726,9 +726,15 @@ dmu_objset_own(const char *name, dmu_objset_type_t type,
 		return (err);
 	}
 
-	/* user accounting requires the dataset to be decrypted */
+	/*
+	 * User accounting requires the dataset to be decrypted and rw.
+	 * We also don't begin user accounting during claiming to help
+	 * speed up pool import times and to keep this txg reserved
+	 * completely for recovery work.
+	 */
 	if ((dmu_objset_userobjspace_upgradable(*osp) ||
 	    dmu_objset_projectquota_upgradable(*osp)) &&
+	    !readonly && !dp->dp_spa->spa_claiming &&
 	    (ds->ds_dir->dd_crypto_obj == 0 || decrypt))
 		dmu_objset_id_quota_upgrade(*osp);
 
@@ -1897,10 +1903,19 @@ dmu_objset_do_userquota_updates(objset_t *os, dmu_tx_t *tx)
 	if (!dmu_objset_userused_enabled(os))
 		return;
 
-	/* if this is a raw receive just return and handle accounting later */
+	/*
+	 * If this is a raw receive just return and handle accounting
+	 * later when we have the keys loaded. We also don't do user
+	 * accounting during claiming since the datasets are not owned
+	 * for the duration of claiming and this txg should only be
+	 * used for recovery.
+	 */
 	if (os->os_encrypted && dmu_objset_is_receiving(os))
 		return;
 
+	if (tx->tx_txg <= os->os_spa->spa_claim_max_txg)
+		return;
+
 	/* Allocate the user/group/project used objects if necessary. */
 	if (DMU_USERUSED_DNODE(os)->dn_type == DMU_OT_NONE) {
 		VERIFY0(zap_create_claim(os,