Add runstate swap helpers

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/blktrace.c b/blktrace.c
index 107a65b..4b5567e 100644
--- a/blktrace.c
+++ b/blktrace.c
@@ -382,8 +382,7 @@
 
 	fifo = fifo_alloc(TRACE_FIFO_SIZE);
 
-	old_state = td->runstate;
-	td_set_runstate(td, TD_SETTING_UP);
+	old_state = td_bump_runstate(td, TD_SETTING_UP);
 
 	td->o.size = 0;
 
@@ -463,7 +462,7 @@
 	fifo_free(fifo);
 	close(fd);
 
-	td_set_runstate(td, old_state);
+	td_restore_runstate(td, old_state);
 
 	if (!td->files_index) {
 		log_err("fio: did not find replay device(s)\n");
diff --git a/filesetup.c b/filesetup.c
index 2744d4f..4bfa470 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -209,8 +209,7 @@
 		did_open = 1;
 	}
 
-	old_runstate = td->runstate;
-	td_set_runstate(td, TD_PRE_READING);
+	old_runstate = td_bump_runstate(td, TD_PRE_READING);
 
 	bs = td->o.max_bs[DDIR_READ];
 	b = malloc(bs);
@@ -234,7 +233,7 @@
 		}
 	}
 
-	td_set_runstate(td, old_runstate);
+	td_restore_runstate(td, old_runstate);
 
 	if (did_open)
 		td->io_ops->close_file(td, f);
@@ -745,8 +744,7 @@
 
 	dprint(FD_FILE, "setup files\n");
 
-	old_state = td->runstate;
-	td_set_runstate(td, TD_SETTING_UP);
+	old_state = td_bump_runstate(td, TD_SETTING_UP);
 
 	if (o->read_iolog_file)
 		goto done;
@@ -925,12 +923,12 @@
 	if (o->create_only)
 		td->done = 1;
 
-	td_set_runstate(td, old_state);
+	td_restore_runstate(td, old_state);
 	return 0;
 err_offset:
 	log_err("%s: you need to specify valid offset=\n", o->name);
 err_out:
-	td_set_runstate(td, old_state);
+	td_restore_runstate(td, old_state);
 	return 1;
 }
 
@@ -980,11 +978,12 @@
 	if (td->o.random_distribution == FIO_RAND_DIST_RANDOM)
 		return 0;
 
-	state = td->runstate;
-	td_set_runstate(td, TD_SETTING_UP);
+	state = td_bump_runstate(td, TD_SETTING_UP);
+
 	for_each_file(td, f, i)
 		__init_rand_distribution(td, f);
-	td_set_runstate(td, state);
+
+	td_restore_runstate(td, state);
 
 	return 1;
 }
diff --git a/fio.h b/fio.h
index 6f5f29f..52f1def 100644
--- a/fio.h
+++ b/fio.h
@@ -475,6 +475,9 @@
 };
 
 extern void td_set_runstate(struct thread_data *, int);
+extern int td_bump_runstate(struct thread_data *, int);
+extern void td_restore_runstate(struct thread_data *, int);
+
 #define TERMINATE_ALL		(-1)
 extern void fio_terminate_threads(int);
 
diff --git a/libfio.c b/libfio.c
index f4aac2e..8eddab8 100644
--- a/libfio.c
+++ b/libfio.c
@@ -172,6 +172,19 @@
 	td->runstate = runstate;
 }
 
+int td_bump_runstate(struct thread_data *td, int new_state)
+{
+	int old_state = td->runstate;
+
+	td_set_runstate(td, new_state);
+	return old_state;
+}
+
+void td_restore_runstate(struct thread_data *td, int old_state)
+{
+	td_set_runstate(td, old_state);
+}
+
 void fio_terminate_threads(int group_id)
 {
 	struct thread_data *td;