MDEV-37753 lock_sec_rec_some_has_impl() unnecessarily fetches history

row_vers_impl_x_locked_low(): If a secondary index record points to
a clustered index record that carries the current transaction identifier,
then there cannot possibly be any implicit locks to that secondary index
record, because those would have been checked before the current
transaction got the implicit lock (modified the clustered index record)
in the first place.

This fix will avoid unnecessary access to undo log and possible BLOB pages,
which may already have been freed in a purge operation.

buf_page_get_zip(): Assert that the page is not marked as freed
in the tablespace. This assertion could fire in a scenario like the
test case when the table is created in ROW_FORMAT=COMPRESSED.

This is a 10.6 version of commit be0e3b2
without a test case.

Author: dr-m

storage/innobase/buf/buf0buf.cc

@@ -2287,6 +2287,7 @@ buf_page_t *buf_page_get_zip(const page_id_t page_id) noexcept
 #ifdef UNIV_DEBUG
   if (!(++buf_dbg_counter % 5771)) buf_pool.validate();
 #endif /* UNIV_DEBUG */
+  ut_ad(bpage->state() >= buf_page_t::UNFIXED);
   return bpage;
 }
 

storage/innobase/row/row0vers.cc

@@ -122,20 +122,21 @@ row_vers_impl_x_locked_low(
 					clust_index->n_core_fields,
 					ULINT_UNDEFINED, &heap);
 
+	trx_t* trx = nullptr;
 	trx_id = row_get_rec_trx_id(clust_rec, clust_index, clust_offsets);
 	if (trx_id == 0) {
 		/* The transaction history was already purged. */
+	done:
 		mem_heap_free(heap);
-		DBUG_RETURN(0);
+		DBUG_RETURN(trx);
 	}
 
 	ut_ad(!clust_index->table->is_temporary());
 
-	trx_t*	trx;
-
 	if (trx_id == caller_trx->id) {
 		trx = caller_trx;
 		trx->reference();
+		goto done;
 	} else {
 		trx = trx_sys.find(caller_trx, trx_id);
 		if (trx == 0) {