MDEV-21718 Assertion in wsrep::client_state::before_command().

An assertion

  `server_state_.rollback_mode() == wsrep::server_state::rm_async`

fired in before_command() when
- thread-handling was set to pool-of-threads and
- a BF abort happened between client session calls to
  wait_rollback_complete_and_acquire_ownership() and before_command().

This commit introduces a test case to reproduce the crash and
updates wsrep-lib submodule to fixed version.

2 files changed, 37 insertions, 0 deletions

diff --git a/mysql-test/suite/galera/t/mdev_21718.cnf b/mysql-test/suite/galera/t/mdev_21718.cnf
new file mode 100644
index 00000000000..9e066597a13
--- /dev/null
+++ b/mysql-test/suite/galera/t/mdev_21718.cnf
@@ -0,0 +1,4 @@
+!include ../galera_2nodes.cnf
+
+[mysqld]
+thread-handling=pool-of-threads
diff --git a/mysql-test/suite/galera/t/mdev_21718.test b/mysql-test/suite/galera/t/mdev_21718.test
new file mode 100644
index 00000000000..413e9da0e83
--- /dev/null
+++ b/mysql-test/suite/galera/t/mdev_21718.test
@@ -0,0 +1,33 @@
+#
+# MDEV-21718 Reproduce a case where BF abort after
+# client session acquires the ownership but before calls
+# before_command() causes an assertion in wsrep-lib.
+#
+--source include/galera_cluster.inc
+--source include/have_innodb.inc
+
+CREATE TABLE t1 (f1 INT PRIMARY KEY) ENGINE=InnoDB;
+
+--let $galera_connection_name = node_1_ctrl
+--let $galera_server_number = 1
+--source include/galera_connect.inc
+
+--connection node_1
+START TRANSACTION;
+INSERT INTO t1 VALUES (1);
+SET DEBUG_SYNC = "wsrep_before_before_command SIGNAL reached WAIT_FOR continue";
+--send COMMIT
+
+--connection node_1_ctrl
+SET DEBUG_SYNC = "now WAIT_FOR reached";
+
+--connection node_2
+INSERT INTO t1 VALUES (1);
+
+# BF abort wakes up node_1 from sync wait.
+--connection node_1
+--error ER_LOCK_DEADLOCK
+--reap
+
+DROP TABLE t1;
+SET DEBUG_SYNC = "RESET";