drbd: bitmap bulk IO: do not always suspend IO

The intention was to only suspend IO if some normal bitmap operation is
supposed to be locked out, not always. If the bulk operation is flaged
as BM_LOCKED_CHANGE_ALLOWED, we do not need to suspend IO.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/block/drbd/drbd_main.c

@@ -3587,18 +3587,20 @@ void drbd_queue_bitmap_io(struct drbd_device *device,
 int drbd_bitmap_io(struct drbd_device *device, int (*io_fn)(struct drbd_device *),
 		char *why, enum bm_flag flags)
 {
+	/* Only suspend io, if some operation is supposed to be locked out */
+	const bool do_suspend_io = flags & (BM_DONT_CLEAR|BM_DONT_SET|BM_DONT_TEST);
 	int rv;
 
 	D_ASSERT(device, current != first_peer_device(device)->connection->worker.task);
 
-	if ((flags & BM_LOCKED_SET_ALLOWED) == 0)
+	if (do_suspend_io)
 		drbd_suspend_io(device);
 
 	drbd_bm_lock(device, why, flags);
 	rv = io_fn(device);
 	drbd_bm_unlock(device);
 
-	if ((flags & BM_LOCKED_SET_ALLOWED) == 0)
+	if (do_suspend_io)
 		drbd_resume_io(device);
 
 	return rv;