MDEV-22446 InnoDB aborts while adding instant column for discarded tablespace

- Instant alter should change the metadata alone when table is
discarded. It shouldn't try to add metadata record in clustered index.
Also make the clustered index to non-instant format.

mysql-test/suite/innodb/r/instant_alter_bugs.result

@@ -169,4 +169,36 @@ DROP FOREIGN KEY fk1,
 CHANGE b d INT UNSIGNED,
 ADD c INT;
 DROP TABLE t2, t1;
+#
+# MDEV-22446 InnoDB aborts while adding instant column
+# for discarded tablespace
+#
+CREATE TABLE t1(c1 INT NOT NULL, c2 INT NOT NULL DEFAULT 0)ENGINE=InnoDB;
+INSERT INTO t1(c1) VALUES(1);
+ALTER TABLE t1 ADD COLUMN c3 INT DEFAULT 10;
+FLUSH TABLES t1 FOR EXPORT;
+backup: t1
+UNLOCK TABLES;
+DROP TABLE t1;
+CREATE TABLE t1(c1 INT NOT NULL)Engine=InnoDB;
+ALTER TABLE t1 DISCARD TABLESPACE;
+ALTER TABLE t1 ADD COLUMN c2 INT NOT NULL;
+Warnings:
+Warning	1814	Tablespace has been discarded for table `t1`
+ALTER TABLE t1 ADD COLUMN c3 INT DEFAULT 10;
+Warnings:
+Warning	1814	Tablespace has been discarded for table `t1`
+restore: t1 .ibd and .cfg files
+ALTER TABLE t1 IMPORT TABLESPACE;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `c1` int(11) NOT NULL,
+  `c2` int(11) NOT NULL,
+  `c3` int(11) DEFAULT 10
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+SELECT * FROM t1;
+c1	c2	c3
+1	0	10
+DROP TABLE t1;
 # End of 10.3 tests

mysql-test/suite/innodb/t/instant_alter_bugs.test

@@ -170,4 +170,38 @@ ALTER TABLE t2
     ADD c INT;
 DROP TABLE t2, t1;
 
+--echo #
+--echo # MDEV-22446 InnoDB aborts while adding instant column
+--echo # for discarded tablespace
+--echo #
+
+let MYSQLD_DATADIR =`SELECT @@datadir`;
+CREATE TABLE t1(c1 INT NOT NULL, c2 INT NOT NULL DEFAULT 0)ENGINE=InnoDB;
+INSERT INTO t1(c1) VALUES(1);
+
+ALTER TABLE t1 ADD COLUMN c3 INT DEFAULT 10;
+--replace_regex /, .*\).*t1.cfg/, Bad file descriptor) t1.cfg/
+FLUSH TABLES t1 FOR EXPORT;
+
+perl;
+do "$ENV{MTR_SUITE_DIR}/include/innodb-util.pl";
+ib_backup_tablespaces("test", "t1");
+EOF
+UNLOCK TABLES;
+DROP TABLE t1;
+
+# Restore of instant table
+CREATE TABLE t1(c1 INT NOT NULL)Engine=InnoDB;
+ALTER TABLE t1 DISCARD TABLESPACE;
+ALTER TABLE t1 ADD COLUMN c2 INT NOT NULL;
+ALTER TABLE t1 ADD COLUMN c3 INT DEFAULT 10;
+# Restore files
+perl;
+do "$ENV{MTR_SUITE_DIR}/include/innodb-util.pl";
+ib_restore_tablespaces("test", "t1");
+EOF
+ALTER TABLE t1 IMPORT TABLESPACE;
+SHOW CREATE TABLE t1;
+SELECT * FROM t1;
+DROP TABLE t1;
 --echo # End of 10.3 tests

storage/innobase/handler/handler0alter.cc

@@ -4441,6 +4441,13 @@ innobase_add_instant_try(
 		return true;
 	}
 
+	/* If the table has been discarded then change the metadata alone
+	and make the index to non-instant format */
+	if (!user_table->space) {
+		index->remove_instant();
+		return false;
+	}
+
 	unsigned i = unsigned(user_table->n_cols) - DATA_N_SYS_COLS;
 	byte trx_id[DATA_TRX_ID_LEN], roll_ptr[DATA_ROLL_PTR_LEN];
 	dfield_set_data(dtuple_get_nth_field(row, i++), field_ref_zero,