MDEV-37123 dict_table_open_on_id() fails to release dict_sys.latch

While updating the persistent defragmentation statistics
for the table, InnoDB opens the table only if it is in cache.
If dict_table_open_on_id() fails to find the table in cache
then it fails to unfreeze dict_sys.latch. This lead to crash

Author: Thirunarayanan

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

@@ -131,3 +131,11 @@ ALTER TABLE t2 STATS_PERSISTENT=1;
 DROP TABLE t2;
 SELECT * FROM mysql.innodb_index_stats;
 database_name	table_name	index_name	last_update	stat_name	stat_value	sample_size	stat_description
+#
+# MDEV-37123  dict_table_open_on_id() fails to release dict_sys.latch
+#
+SET GLOBAL innodb_defragment_stats_accuracy=1;
+CREATE TABLE t (f INT,f2 CHAR(1),KEY k1 (f2),FULLTEXT KEY(f2),
+FOREIGN KEY(f2) REFERENCES t (f3)) ENGINE=InnoDB;
+ERROR HY000: Can't create table `test`.`t` (errno: 150 "Foreign key constraint is incorrectly formed")
+SET GLOBAL innodb_defragment_stats_accuracy=default;

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

@@ -86,3 +86,12 @@ ALTER TABLE t2 STATS_PERSISTENT=1;
 DROP TABLE t2;
 
 SELECT * FROM mysql.innodb_index_stats;
+
+--echo #
+--echo # MDEV-37123  dict_table_open_on_id() fails to release dict_sys.latch
+--echo #
+SET GLOBAL innodb_defragment_stats_accuracy=1;
+--error ER_CANT_CREATE_TABLE
+CREATE TABLE t (f INT,f2 CHAR(1),KEY k1 (f2),FULLTEXT KEY(f2),
+                FOREIGN KEY(f2) REFERENCES t (f3)) ENGINE=InnoDB;
+SET GLOBAL innodb_defragment_stats_accuracy=default;

storage/innobase/dict/dict0dict.cc

@@ -927,6 +927,8 @@ dict_table_t *dict_table_open_on_id(table_id_t table_id, bool dict_locked,
     else if (table)
       table->acquire();
   }
+  else if (!dict_locked)
+    dict_sys.unfreeze();
 
   return table;
 }