MDEV-31124 Innodb_data_written miscounts doublewrites

When commit a5a2ef07
implemented asynchronous doublewrite, the writes via
the doublewrite buffer started to be counted incorrectly,
without multiplying them by innodb_page_size.

srv_export_innodb_status(): Correctly count the
Innodb_data_written.

buf_dblwr_t: Remove submitted(), because it is close to written()
and only Innodb_data_written was interested in it. According to
its name, it should count completed and not submitted writes.

Tested by: Axel Schwenke

storage/innobase/buf/buf0dblwr.cc

@@ -582,7 +582,6 @@ bool buf_dblwr_t::flush_buffered_writes(const ulint size)
   const bool multi_batch= block1 + static_cast<uint32_t>(size) != block2 &&
     old_first_free > size;
   flushing_buffered_writes= 1 + multi_batch;
-  pages_submitted+= old_first_free;
   /* Now safe to release the mutex. */
   mysql_mutex_unlock(&mutex);
 #ifdef UNIV_DEBUG

storage/innobase/include/buf0dblwr.h

@@ -66,8 +66,6 @@ class buf_dblwr_t
   bool batch_running;
   /** number of expected flush_buffered_writes_completed() calls */
   unsigned flushing_buffered_writes;
-  /** pages submitted to flush_buffered_writes() */
-  ulint pages_submitted;
   /** number of flush_buffered_writes_completed() calls */
   ulint writes_completed;
   /** number of pages written by flush_buffered_writes_completed() */
@@ -92,9 +90,6 @@ class buf_dblwr_t
 
   /** Acquire the mutex */
   void lock() { mysql_mutex_lock(&mutex); }
-  /** @return the number of submitted page writes */
-  ulint submitted() const
-  { mysql_mutex_assert_owner(&mutex); return pages_submitted; }
   /** @return the number of completed batches */
   ulint batches() const
   { mysql_mutex_assert_owner(&mutex); return writes_completed; }

storage/innobase/srv/srv0srv.cc

@@ -1013,13 +1013,14 @@ srv_export_innodb_status(void)
 
 	if (buf_dblwr.is_initialised()) {
 		buf_dblwr.lock();
-		dblwr = buf_dblwr.submitted();
-		export_vars.innodb_dblwr_pages_written = buf_dblwr.written();
+		dblwr = buf_dblwr.written();
+		export_vars.innodb_dblwr_pages_written = dblwr;
 		export_vars.innodb_dblwr_writes = buf_dblwr.batches();
 		buf_dblwr.unlock();
 	}
 
-	export_vars.innodb_data_written = srv_stats.data_written + dblwr;
+	export_vars.innodb_data_written = srv_stats.data_written
+		+ (dblwr << srv_page_size_shift);
 
 	export_vars.innodb_buffer_pool_read_requests
 		= buf_pool.stat.n_page_gets;