MDEV-22284 Aria table key read crash because wrong index used

When restoring lastinx last_key.keyinfo must be updated as well. The
good example is in _ma_check_index().

The point of failure is extra(HA_EXTRA_NO_KEYREAD) in
ha_maria::get_auto_increment():

  1. extra(HA_EXTRA_KEYREAD) saves lastinx;
  2. maria_rkey() changes index, so the lastinx and last_key.keyinfo;
  3. extra(HA_EXTRA_NO_KEYREAD) restores lastinx but not
     last_key.keyinfo.

So we have discrepancy between lastinx and last_key.keyinfo after 3.

mysql-test/suite/maria/maria.result

@@ -2850,3 +2850,14 @@ insert into t1 values (8,'0');
 ERROR HY000: Table 't1' was locked with a READ lock and can't be updated
 unlock tables;
 drop table t1;
+#
+# MDEV-22284 Aria table key read crash because wrong index used
+#
+create table t1 (
+a int auto_increment,
+b int, c int,
+key(c, a), unique(b)
+) engine aria
+partition by hash (b);
+replace into t1 values (1, 0, 0), (2, 0, 0), (0, 0, 0);
+drop table t1;

mysql-test/suite/maria/maria.test

@@ -2093,3 +2093,16 @@ aria_page_checksum=$default_checksum,
 aria_log_file_size=$default_log_file_size;
 --enable_result_log
 --enable_query_log
+
+--echo #
+--echo # MDEV-22284 Aria table key read crash because wrong index used
+--echo #
+create table t1 (
+    a int auto_increment,
+    b int, c int,
+    key(c, a), unique(b)
+) engine aria
+partition by hash (b);
+replace into t1 values (1, 0, 0), (2, 0, 0), (0, 0, 0);
+# cleanup
+drop table t1;

storage/maria/ma_extra.c

@@ -213,7 +213,13 @@ int maria_extra(MARIA_HA *info, enum ha_extra_function function,
 	    info->last_key.data + share->base.max_key_length*2,
 	    info->save_lastkey_data_length + info->save_lastkey_ref_length);
       info->update=	info->save_update | HA_STATE_WRITTEN;
-      info->lastinx=	info->save_lastinx;
+      if (info->lastinx != info->save_lastinx)             /* Index changed */
+      {
+        info->lastinx = info->save_lastinx;
+        info->last_key.keyinfo= info->s->keyinfo + info->lastinx;
+        info->last_key.flag= 0;
+        info->page_changed=1;
+      }
       info->cur_row.lastpos= info->save_lastpos;
       info->last_key.data_length= info->save_lastkey_data_length;
       info->last_key.ref_length= info->save_lastkey_ref_length;