MDEV-15323 Follow-up to MDEV-14905: Skip FTS processing if innodb_read_only

fts_cmp_set_sync_doc_id(), fts_load_stopword(): Start the transaction
in read-only mode if innodb_read_only is set.

fts_update_sync_doc_id(), fts_commit_table(), fts_sync(),
fts_optimize_table(): Return DB_READ_ONLY if innodb_read_only is set.

fts_doc_fetch_by_doc_id(), fts_table_fetch_doc_ids():
Remove the code to start an internal transaction or to roll back,
because this is a read-only operation.

storage/innobase/fts/fts0fts.cc

@@ -2699,7 +2699,11 @@ fts_cmp_set_sync_doc_id(
 	fts_table.parent = table->name.m_name;
 
 	trx = trx_allocate_for_background();
-	trx_start_internal(trx);
+	if (srv_read_only_mode) {
+		trx_start_internal_read_only(trx);
+	} else {
+		trx_start_internal(trx);
+	}
 
 	trx->op_info = "update the next FTS document id";
 
@@ -2808,6 +2812,10 @@ fts_update_sync_doc_id(
 	fts_cache_t*	cache = table->fts->cache;
 	char		fts_name[MAX_FULL_NAME_LEN];
 
+	if (srv_read_only_mode) {
+		return DB_READ_ONLY;
+	}
+
 	fts_table.suffix = "CONFIG";
 	fts_table.table_id = table->id;
 	fts_table.type = FTS_COMMON_TABLE;
@@ -3052,6 +3060,10 @@ fts_commit_table(
 /*=============*/
 	fts_trx_table_t*	ftt)		/*!< in: FTS table to commit*/
 {
+	if (srv_read_only_mode) {
+		return DB_READ_ONLY;
+	}
+
 	const ib_rbt_node_t*	node;
 	ib_rbt_t*		rows;
 	dberr_t			error = DB_SUCCESS;
@@ -3796,7 +3808,6 @@ fts_doc_fetch_by_doc_id(
 	trx_t*		trx = trx_allocate_for_background();
 	que_t*          graph;
 
-	trx_start_internal(trx);
 	trx->op_info = "fetching indexed FTS document";
 
 	/* The FTS index can be supplied by caller directly with
@@ -3884,13 +3895,7 @@ fts_doc_fetch_by_doc_id(
 	}
 
 	error = fts_eval_sql(trx, graph);
-
-	if (error == DB_SUCCESS) {
-		fts_sql_commit(trx);
-	} else {
-		fts_sql_rollback(trx);
-	}
-
+	fts_sql_commit(trx);
 	trx_free_for_background(trx);
 
 	if (!get_doc) {
@@ -4359,6 +4364,10 @@ fts_sync(
 	bool		wait,
 	bool		has_dict)
 {
+	if (srv_read_only_mode) {
+		return DB_READ_ONLY;
+	}
+
 	ulint		i;
 	dberr_t		error = DB_SUCCESS;
 	fts_cache_t*	cache = sync->table->fts->cache;
@@ -7355,7 +7364,11 @@ fts_load_stopword(
 
 	if (!trx) {
 		trx = trx_allocate_for_background();
-		trx_start_internal(trx);
+		if (srv_read_only_mode) {
+			trx_start_internal_read_only(trx);
+		} else {
+			trx_start_internal(trx);
+		}
 		trx->op_info = "upload FTS stopword";
 		new_trx = TRUE;
 	}

storage/innobase/fts/fts0opt.cc

@@ -989,7 +989,6 @@ fts_table_fetch_doc_ids(
 
 	if (!trx) {
 		trx = trx_allocate_for_background();
-		trx_start_internal(trx);
 		alloc_bk_trx = TRUE;
 	}
 
@@ -1018,17 +1017,14 @@ fts_table_fetch_doc_ids(
 		"CLOSE c;");
 
 	error = fts_eval_sql(trx, graph);
+	fts_sql_commit(trx);
 
 	mutex_enter(&dict_sys->mutex);
 	que_graph_free(graph);
 	mutex_exit(&dict_sys->mutex);
 
 	if (error == DB_SUCCESS) {
-		fts_sql_commit(trx);
-
 		ib_vector_sort(doc_ids->doc_ids, fts_update_doc_id_cmp);
-	} else {
-		fts_sql_rollback(trx);
 	}
 
 	if (alloc_bk_trx) {
@@ -2442,6 +2438,10 @@ fts_optimize_table(
 /*===============*/
 	dict_table_t*	table)	/*!< in: table to optimiza */
 {
+	if (srv_read_only_mode) {
+		return DB_READ_ONLY;
+	}
+
 	dberr_t		error = DB_SUCCESS;
 	fts_optimize_t*	optim = NULL;
 	fts_t*		fts = table->fts;