io_uring: fail links when poll fails

Don't forget to cancel all linked requests of poll request when
__io_arm_poll_handler() failed.

Fixes: aa43477 ("io_uring: poll rework")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a78aad962460f9fdfe4aa4c0b62425c88f9415bc.1655852245.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -7405,6 +7405,8 @@ static int io_poll_add(struct io_kiocb *req, unsigned int issue_flags)
 	ipt.pt._qproc = io_poll_queue_proc;
 
 	ret = __io_arm_poll_handler(req, &req->poll, &ipt, poll->events);
+	if (!ret && ipt.error)
+		req_set_fail(req);
 	ret = ret ?: ipt.error;
 	if (ret)
 		__io_req_complete(req, issue_flags, ret, 0);