MDEV-24971 InnoDB access freed virtual column after rollback of secondary index

Problem:
========
 InnoDB fails to clean the index stub if it fails to add the
virtual index which contains new virtual column. But it clears
the newly virtual column from index in clear_added_indexes()
during inplace_alter_table. On commit, InnoDB evicts and
reload the table. In case of rollback, it doesn't happen.
InnoDB clears the ABORTED index while opening the table
or doing the DDL. In the mean time, InnoDB can access
the dropped virtual index columns while creating prebuilt
or rollback of concurrent DML.

Solution:
==========
(1) InnoDB should maintain newly added virtual column while
rollbacking the newly added virtual index.
(2) InnoDB must not defer the index removal
if the alter table is executed with LOCK=EXCLUSIVE.
(3) For LOCK=SHARED, InnoDB should check whether the table
has any other transaction lock other than alter transaction
before deferring the index stub.

Replaced has_new_v_col with dict_add_vcol_info in dict_index_t to
indicate whether the index has any new virtual column.

dict_index_t::has_new_v_col(): Returns whether the index has
newly added virtual column, it doesn't say which columns are
newly added virtual column

ha_innobase_inplace_ctx::is_new_vcol(): Return whether the
given column is added as a part of the current alter.

ha_innobase_inplace_ctx::clean_new_vcol_index(): Copy the newly
added virtual column to new_vcol_info in dict_index_t. Replace
the column in the index fields with virtual column stored
in new_vcol_info.

dict_index_t::assign_new_v_col(): Store the number of virtual
column added in index as a part of alter table.

dict_index_t::get_n_new_vcol(): Get the number of newly added
virtual column

dict_index_t::assign_drop_v_col(): Allocate the memory for
adding new virtual column in new_vcol_info.

dict_index_t::add_drop_v_col(): Add the newly added virtual
column in new_vcol_info.

dict_table_t::has_lock_for_other_trx(): Whether the table has
any other transaction lock than given transaction.

row_merge_drop_indexes(): Add parameter alter_trx and check
whether the table has any other lock than alter transaction.

2 files changed, 140 insertions, 0 deletions

diff --git a/mysql-test/suite/gcol/r/virtual_index_drop.result b/mysql-test/suite/gcol/r/virtual_index_drop.result
new file mode 100644
index 00000000000..012e61be459
--- /dev/null
+++ b/mysql-test/suite/gcol/r/virtual_index_drop.result
@@ -0,0 +1,69 @@
+#
+# MDEV-24971 InnoDB access freed virtual column
+#	after rollback of secondary index
+#
+CREATE TABLE t1(f1 INT, f2 INT AS (f1 + 2) VIRTUAL)ENGINE=InnoDB;
+INSERT INTO t1(f1) VALUES(1), (1);
+ALTER TABLE t1 ADD UNIQUE INDEX(f2), ALGORITHM=INPLACE, LOCK=EXCLUSIVE;
+ERROR 23000: Duplicate entry '3' for key 'f2'
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `f1` int(11) DEFAULT NULL,
+  `f2` int(11) GENERATED ALWAYS AS (`f1` + 2) VIRTUAL
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+DROP TABLE t1;
+CREATE TABLE t1(f1 INT, f2 INT AS (f1 + 2) VIRTUAL)ENGINE=InnoDB;
+INSERT INTO t1(f1) VALUES(1), (1);
+ALTER TABLE t1 ADD UNIQUE INDEX(f2), ALGORITHM=INPLACE, LOCK=SHARED;
+ERROR 23000: Duplicate entry '3' for key 'f2'
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `f1` int(11) DEFAULT NULL,
+  `f2` int(11) GENERATED ALWAYS AS (`f1` + 2) VIRTUAL
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+DROP TABLE t1;
+CREATE TABLE t1(f1 INT, f2 INT AS (f1) VIRTUAL)ENGINE=InnoDB;
+SET DEBUG_DBUG="+d,create_index_fail";
+SET DEBUG_SYNC="innodb_inplace_alter_table_enter SIGNAL con1_go WAIT_FOR alter_signal";
+ALTER TABLE t1 ADD COLUMN f3 INT AS (f1) VIRTUAL, ADD INDEX(f2, f3);
+connect con1,localhost,root,,,;
+SET DEBUG_SYNC="now WAIT_FOR con1_go";
+BEGIN;
+SELECT * FROM t1;
+f1	f2
+SET DEBUG_SYNC="now SIGNAL alter_signal";
+connection default;
+ERROR 23000: Duplicate entry '' for key '*UNKNOWN*'
+connection con1;
+rollback;
+connection default;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `f1` int(11) DEFAULT NULL,
+  `f2` int(11) GENERATED ALWAYS AS (`f1`) VIRTUAL
+) ENGINE=InnoDB DEFAULT CHARSET=latin1
+DROP TABLE t1;
+CREATE TABLE t1(f1 INT, f2 INT AS (f1) VIRTUAL)ENGINE=InnoDB;
+SET DEBUG_DBUG="+d,create_index_fail";
+SET DEBUG_SYNC="innodb_inplace_alter_table_enter SIGNAL con1_go WAIT_FOR alter_signal";
+ALTER TABLE t1 ADD INDEX(f2);
+connection con1;
+SET DEBUG_SYNC="now WAIT_FOR con1_go";
+BEGIN;
+INSERT INTO t1(f1) VALUES(1);
+SET DEBUG_SYNC="now SIGNAL alter_signal";
+connection default;
+ERROR 23000: Duplicate entry '' for key '*UNKNOWN*'
+connection con1;
+rollback;
+connection default;
+disconnect con1;
+DROP TABLE t1;
+CREATE TABLE t1(f1 CHAR(100), f2 CHAR(100) as (f1) VIRTUAL)ENGINE=InnoDB;
+ALTER TABLE t1 ADD COLUMN f3 CHAR(100) AS (f2) VIRTUAL, ADD INDEX(f3(10), f1, f3(12));
+ERROR 42S21: Duplicate column name 'f3'
+DROP TABLE t1;
+SET DEBUG_SYNC=RESET;
diff --git a/mysql-test/suite/gcol/t/virtual_index_drop.test b/mysql-test/suite/gcol/t/virtual_index_drop.test
new file mode 100644
index 00000000000..016832b9e6d
--- /dev/null
+++ b/mysql-test/suite/gcol/t/virtual_index_drop.test
@@ -0,0 +1,71 @@
+--source include/have_innodb.inc
+--source include/have_debug.inc
+
+--echo #
+--echo # MDEV-24971 InnoDB access freed virtual column
+--echo #	after rollback of secondary index
+--echo #
+
+# Exclusive lock must not defer the index removal
+
+CREATE TABLE t1(f1 INT, f2 INT AS (f1 + 2) VIRTUAL)ENGINE=InnoDB;
+INSERT INTO t1(f1) VALUES(1), (1);
+--error ER_DUP_ENTRY
+ALTER TABLE t1 ADD UNIQUE INDEX(f2), ALGORITHM=INPLACE, LOCK=EXCLUSIVE;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+# If Shared lock and table doesn't have any other open handle
+# then InnoDB must not defer the index removal
+
+CREATE TABLE t1(f1 INT, f2 INT AS (f1 + 2) VIRTUAL)ENGINE=InnoDB;
+INSERT INTO t1(f1) VALUES(1), (1);
+--error ER_DUP_ENTRY
+ALTER TABLE t1 ADD UNIQUE INDEX(f2), ALGORITHM=INPLACE, LOCK=SHARED;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+# InnoDB should store the newly dropped virtual column into
+# new_vcol_info in index when rollback of alter happens
+
+CREATE TABLE t1(f1 INT, f2 INT AS (f1) VIRTUAL)ENGINE=InnoDB;
+SET DEBUG_DBUG="+d,create_index_fail";
+SET DEBUG_SYNC="innodb_inplace_alter_table_enter SIGNAL con1_go WAIT_FOR alter_signal";
+SEND ALTER TABLE t1 ADD COLUMN f3 INT AS (f1) VIRTUAL, ADD INDEX(f2, f3);
+connect(con1,localhost,root,,,);
+SET DEBUG_SYNC="now WAIT_FOR con1_go";
+BEGIN;
+SELECT * FROM t1;
+SET DEBUG_SYNC="now SIGNAL alter_signal";
+connection default;
+--error ER_DUP_ENTRY
+reap;
+connection con1;
+rollback;
+connection default;
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+CREATE TABLE t1(f1 INT, f2 INT AS (f1) VIRTUAL)ENGINE=InnoDB;
+SET DEBUG_DBUG="+d,create_index_fail";
+SET DEBUG_SYNC="innodb_inplace_alter_table_enter SIGNAL con1_go WAIT_FOR alter_signal";
+send ALTER TABLE t1 ADD INDEX(f2);
+connection con1;
+SET DEBUG_SYNC="now WAIT_FOR con1_go";
+BEGIN;
+INSERT INTO t1(f1) VALUES(1);
+SET DEBUG_SYNC="now SIGNAL alter_signal";
+connection default;
+--error ER_DUP_ENTRY
+reap;
+connection con1;
+rollback;
+connection default;
+disconnect con1;
+DROP TABLE t1;
+
+CREATE TABLE t1(f1 CHAR(100), f2 CHAR(100) as (f1) VIRTUAL)ENGINE=InnoDB;
+--error ER_DUP_FIELDNAME
+ALTER TABLE t1 ADD COLUMN f3 CHAR(100) AS (f2) VIRTUAL, ADD INDEX(f3(10), f1, f3(12));
+DROP TABLE t1;
+SET DEBUG_SYNC=RESET;