flist: add flist_first_entry()

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/verify.c b/verify.c
index 2615701..11963e1 100644
--- a/verify.c
+++ b/verify.c
@@ -1082,7 +1082,7 @@
 		assert(ipo->flags & IP_F_ONRB);
 		ipo->flags &= ~IP_F_ONRB;
 	} else if (!flist_empty(&td->io_hist_list)) {
-		ipo = flist_entry(td->io_hist_list.next, struct io_piece, list);
+		ipo = flist_first_entry(&td->io_hist_list, struct io_piece, list);
 
 		/*
 		 * Ensure that the associated IO has completed
@@ -1187,7 +1187,7 @@
 			continue;
 
 		while (!flist_empty(&list)) {
-			io_u = flist_entry(list.next, struct io_u, verify_list);
+			io_u = flist_first_entry(&list, struct io_u, verify_list);
 			flist_del(&io_u->verify_list);
 
 			ret = verify_io_u(td, io_u);