drbd: allow petabyte storage on 64bit arch

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index d17f2ed..be46084 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -577,7 +577,7 @@
 		size = BM_BLOCK_SIZE;
 		bit  = drbd_bm_find_next(mdev, mdev->bm_resync_fo);
 
-		if (bit == -1UL) {
+		if (bit == DRBD_END_OF_BITMAP) {
 			mdev->bm_resync_fo = drbd_bm_bits(mdev);
 			mdev->resync_work.cb = w_resync_inactive;
 			put_ldev(mdev);