MDEV-33731 Only iterate over m_locked_partitions in update_next_auto_inc_val()

Only locked will participate in the query in this case. Chances are
that not-locked partitions were not opened, which is the cause of the
crash in the added test case spider/bugfix.mdev_33731 without this
patch.

sql/ha_partition.cc

@@ -10753,18 +10753,19 @@ int ha_partition::update_next_auto_inc_val()
 
 bool ha_partition::need_info_for_auto_inc()
 {
-  handler **file= m_file;
   DBUG_ENTER("ha_partition::need_info_for_auto_inc");
 
-  do
+  for (uint i= bitmap_get_first_set(&m_locked_partitions);
+       i < m_tot_parts;
+       i= bitmap_get_next_set(&m_locked_partitions, i))
   {
-    if ((*file)->need_info_for_auto_inc())
+    if ((m_file[i])->need_info_for_auto_inc())
     {
       /* We have to get new auto_increment values from handler */
       part_share->auto_inc_initialized= FALSE;
       DBUG_RETURN(TRUE);
     }
-  } while (*(++file));
+  }
   DBUG_RETURN(FALSE);
 }
 

storage/spider/mysql-test/spider/bugfix/r/mdev_33731.result

+for master_1
+for child2
+for child3
+CREATE TABLE t (a INT) ENGINE=Spider PARTITION BY LIST (a) PARTITIONS 2 (PARTITION p1 VALUES IN (0,1),PARTITION p2 VALUES IN (2,3));
+DELETE FROM t PARTITION (p2);
+ERROR HY000: Unable to connect to foreign data source: localhost
+drop table t;
+for master_1
+for child2
+for child3

storage/spider/mysql-test/spider/bugfix/t/mdev_33731.test

+--disable_query_log
+--disable_result_log
+--source ../../t/test_init.inc
+--enable_result_log
+--enable_query_log
+
+CREATE TABLE t (a INT) ENGINE=Spider PARTITION BY LIST (a) PARTITIONS 2 (PARTITION p1 VALUES IN (0,1),PARTITION p2 VALUES IN (2,3));
+--error ER_CONNECT_TO_FOREIGN_DATA_SOURCE
+DELETE FROM t PARTITION (p2);
+drop table t;
+
+--disable_query_log
+--disable_result_log
+--source ../../t/test_deinit.inc
+--enable_result_log
+--enable_query_log