Remove the redundant variable fil_n_file_opened

extra/mariabackup/fil_cur.cc

@@ -110,7 +110,6 @@ xb_fil_node_close_file(
 
 	ut_a(fil_system->n_open > 0);
 	fil_system->n_open--;
-	fil_n_file_opened--;
 
 	if (node->space->purpose == FIL_TYPE_TABLESPACE &&
 	    fil_is_user_tablespace_id(node->space->id)) {
@@ -179,7 +178,6 @@ xb_fil_cur_open(
 		mutex_enter(&fil_system->mutex);
 
 		fil_system->n_open++;
-		fil_n_file_opened++;
 
 		if (node->space->purpose == FIL_TYPE_TABLESPACE &&
 		    fil_is_user_tablespace_id(node->space->id)) {

storage/innobase/fil/fil0fil.cc

@@ -138,9 +138,6 @@ ulint	fil_n_pending_log_flushes		= 0;
 /** Number of pending tablespace flushes */
 ulint	fil_n_pending_tablespace_flushes	= 0;
 
-/** Number of files currently open */
-ulint	fil_n_file_opened			= 0;
-
 /** The null file address */
 fil_addr_t	fil_addr_null = {FIL_NULL, 0};
 
@@ -758,7 +755,6 @@ fil_node_open_file(
 	ut_a(node->is_open());
 
 	fil_system->n_open++;
-	fil_n_file_opened++;
 
 	if (fil_space_belongs_in_lru(space)) {
 
@@ -797,7 +793,6 @@ fil_node_close_file(
 	ut_ad(!node->is_open());
 	ut_a(fil_system->n_open > 0);
 	fil_system->n_open--;
-	fil_n_file_opened--;
 
 	if (fil_space_belongs_in_lru(node->space)) {
 

storage/innobase/include/fil0fil.h

@@ -443,9 +443,6 @@ extern ulint	fil_n_pending_log_flushes;
 /** Number of pending tablespace flushes */
 extern ulint	fil_n_pending_tablespace_flushes;
 
-/** Number of files currently open */
-extern ulint	fil_n_file_opened;
-
 #ifndef UNIV_INNOCHECKSUM
 
 /** Look up a tablespace.

storage/innobase/include/srv0srv.h

@@ -1020,7 +1020,7 @@ struct export_var_t{
 	ulint innodb_system_rows_inserted; /*!< srv_n_system_rows_inserted */
 	ulint innodb_system_rows_updated; /*!< srv_n_system_rows_updated */
 	ulint innodb_system_rows_deleted; /*!< srv_n_system_rows_deleted*/
-	ulint innodb_num_open_files;		/*!< fil_n_file_opened */
+	ulint innodb_num_open_files;		/*!< fil_system_t::n_open */
 	ulint innodb_truncated_status_writes;	/*!< srv_truncated_status_writes */
 	ulint innodb_available_undo_logs;       /*!< srv_available_undo_logs
 						*/

storage/innobase/srv/srv0mon.cc

@@ -1960,7 +1960,7 @@ srv_mon_process_existing_counter(
 		break;
 
 	case MONITOR_OVLD_N_FILE_OPENED:
-		value = fil_n_file_opened;
+		value = fil_system->n_open;
 		break;
 
 	case MONITOR_OVLD_IBUF_MERGE_INSERT:

storage/innobase/srv/srv0srv.cc

@@ -1626,7 +1626,7 @@ srv_export_innodb_status(void)
 	export_vars.innodb_system_rows_deleted =
 		srv_stats.n_system_rows_deleted;
 
-	export_vars.innodb_num_open_files = fil_n_file_opened;
+	export_vars.innodb_num_open_files = fil_system->n_open;
 
 	export_vars.innodb_truncated_status_writes =
 		srv_truncated_status_writes;