Fixed MDEV-365 "Got assertion when doing alter table on a partition"

mysql-test/r/partition.result:
  Added test case
mysql-test/t/partition.test:
  Added test case
sql/sql_partition.cc:
  Do mysql_trans_prepare_alter_copy_data() after all original tables are locked.
  (We don't want to disable transactions for the original tables, that still may be in the cache)
sql/sql_table.cc:
  Fixed two wrong DBUG_ENTER

mysql-test/r/partition.result

@@ -2473,3 +2473,17 @@ SELECT * FROM vtmp;
 1
 DROP VIEW vtmp;
 DROP TABLE t1;
+#
+# MDEV-365 "Got assertion when doing alter table on a partition"
+#
+CREATE TABLE t1 ( i INT ) ENGINE=Aria PARTITION BY HASH(i) PARTITIONS 2;
+INSERT INTO t1 VALUES (1),(2),(2),(3),(4);
+ALTER TABLE t1 ADD PARTITION PARTITIONS 2;
+SELECT * from t1 order by i;
+i
+1
+2
+2
+3
+4
+DROP TABLE t1;

mysql-test/t/partition.test

@@ -2476,3 +2476,13 @@ SELECT 1 FROM t1 AS t1_0 JOIN t1 ON t1_0.a LIKE (SELECT 1 FROM t1);
 SELECT * FROM vtmp;
 DROP VIEW vtmp;
 DROP TABLE t1;
+
+--echo #
+--echo # MDEV-365 "Got assertion when doing alter table on a partition"
+--echo #
+
+CREATE TABLE t1 ( i INT ) ENGINE=Aria PARTITION BY HASH(i) PARTITIONS 2;
+INSERT INTO t1 VALUES (1),(2),(2),(3),(4);
+ALTER TABLE t1 ADD PARTITION PARTITIONS 2;
+SELECT * from t1 order by i;
+DROP TABLE t1;

sql/sql_partition.cc

@@ -5500,10 +5500,12 @@ static bool mysql_change_partitions(ALTER_PARTITION_PARAM_TYPE *lpt)
 
   build_table_filename(path, sizeof(path) - 1, lpt->db, lpt->table_name, "", 0);
 
-  if(mysql_trans_prepare_alter_copy_data(thd))
+  /* First lock the original tables */
+  if (file->ha_external_lock(thd, F_WRLCK))
     DBUG_RETURN(TRUE);
 
-  if (file->ha_external_lock(thd, F_WRLCK))
+  /* Disable transactions for all new tables */
+  if (mysql_trans_prepare_alter_copy_data(thd))
     DBUG_RETURN(TRUE);
 
   /* TODO: test if bulk_insert would increase the performance */

sql/sql_table.cc

@@ -7247,7 +7247,7 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
 
 bool mysql_trans_prepare_alter_copy_data(THD *thd)
 {
-  DBUG_ENTER("mysql_prepare_alter_copy_data");
+  DBUG_ENTER("mysql_trans_prepare_alter_copy_data");
   /*
     Turn off recovery logging since rollback of an alter table is to
     delete the new table so there is no need to log the changes to it.
@@ -7267,7 +7267,7 @@ bool mysql_trans_prepare_alter_copy_data(THD *thd)
 bool mysql_trans_commit_alter_copy_data(THD *thd)
 {
   bool error= FALSE;
-  DBUG_ENTER("mysql_commit_alter_copy_data");
+  DBUG_ENTER("mysql_trans_commit_alter_copy_data");
 
   if (ha_enable_transaction(thd, TRUE))
     DBUG_RETURN(TRUE);