MDEV-27500 buf_page_free() fails to drop the adaptive hash index

The function buf_page_free() that was introduced
in commit a35b4ae (MDEV-15528)
failed to remove any adaptive hash index entries for the page
before freeing the page.

This caused an assertion failure on shutdown of 10.6 server of
in the function buf_pool_t::clear_hash_index() with the expression:
(s >= buf_page_t::UNFIXED || s == buf_page_t::REMOVE_HASH).
The assertion would fail for a block that is in the freed state.

The failing assertion was added in
commit aaef2e1
in the 10.6 branch.

Thanks to Matthias Leich for finding the bug and testing the fix.

storage/innobase/buf/buf0buf.cc

@@ -2,7 +2,7 @@
 
 Copyright (c) 1995, 2018, Oracle and/or its affiliates. All Rights Reserved.
 Copyright (c) 2008, Google Inc.
-Copyright (c) 2013, 2021, MariaDB Corporation.
+Copyright (c) 2013, 2022, MariaDB Corporation.
 
 Portions of this file contain modifications contributed and copyrighted by
 Google, Inc. Those modifications are gratefully acknowledged and are described
@@ -2500,6 +2500,11 @@ void buf_page_free(fil_space_t *space, uint32_t page, mtr_t *mtr,
       rw_lock_x_lock_inline(&block->lock, 0, file, line);
       buf_block_dbg_add_level(block, SYNC_NO_ORDER_CHECK);
 
+#ifdef BTR_CUR_HASH_ADAPT
+      if (block->index)
+        btr_search_drop_page_hash_index(block);
+#endif /* BTR_CUR_HASH_ADAPT */
+
       block->page.status= buf_page_t::FREED;
       return;
     }