io_uring: refactor timeout cancellation cqe posting

io_fill_cqe*() is not always the best way to post CQEs just because
there is enough of infrastructure on top. Replace a raw call to a
variant of it inside of io_timeout_cancel(), which also saves us some
bloating and might help with batching later.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/46113ec4345764b4aef3b384ce38cceabaeedcbb.1647481208.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -6471,10 +6471,7 @@ static int io_timeout_cancel(struct io_ring_ctx *ctx, __u64 user_data)
 
 	if (IS_ERR(req))
 		return PTR_ERR(req);
-
-	req_set_fail(req);
-	io_fill_cqe_req(req, -ECANCELED, 0);
-	io_put_req_deferred(req);
+	io_req_task_queue_fail(req, -ECANCELED);
 	return 0;
 }