MDEV-24832 Root page AHI removal fails during rollback of bulk insert

This failure is caused by commit 43ca6059
(MDEV-24720). InnoDB fails to remove the ahi entries
during rollback of bulk insert operation. InnoDB should
remove the AHI entries of root page before reinitialising it.

Reviewed-by: Marko Mäkelä

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

@@ -25,5 +25,12 @@ ROLLBACK;
 CHECK TABLE t1;
 Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK
+#
+# MDEV-24832 Root page AHI Removal fails fails during
+#		bulk index rollback
+#
+BEGIN;
+INSERT INTO t1 SELECT * FROM seq_1_to_500;
+ROLLBACK;
 DROP TABLE t1;
 SET GLOBAL innodb_adaptive_hash_index = @save_ahi;

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

@@ -24,5 +24,12 @@ BEGIN;
 INSERT INTO t1 SELECT * FROM seq_1_to_65536;
 ROLLBACK;
 CHECK TABLE t1;
+--echo #
+--echo # MDEV-24832 Root page AHI Removal fails fails during
+--echo #		bulk index rollback
+--echo #
+BEGIN;
+INSERT INTO t1 SELECT * FROM seq_1_to_500;
+ROLLBACK;
 DROP TABLE t1;
 SET GLOBAL innodb_adaptive_hash_index = @save_ahi;

storage/innobase/btr/btr0btr.cc

@@ -1209,16 +1209,16 @@ void dict_index_t::clear(que_thr_t *thr)
 #endif
                          );
 
-    mtr.memset(root_block, PAGE_HEADER + PAGE_BTR_SEG_LEAF,
-               FSEG_HEADER_SIZE, 0);
-    if (fseg_create(table->space, PAGE_HEADER + PAGE_BTR_SEG_LEAF, &mtr, false,
-                    root_block))
-      btr_root_page_init(root_block, id, this, &mtr);
 #ifdef BTR_CUR_HASH_ADAPT
     if (root_block->index)
       btr_search_drop_page_hash_index(root_block);
     ut_ad(n_ahi_pages() == 0);
 #endif
+    mtr.memset(root_block, PAGE_HEADER + PAGE_BTR_SEG_LEAF,
+               FSEG_HEADER_SIZE, 0);
+    if (fseg_create(table->space, PAGE_HEADER + PAGE_BTR_SEG_LEAF, &mtr, false,
+                    root_block))
+      btr_root_page_init(root_block, id, this, &mtr);
   }
 
   mtr.commit();