io_uring/zcrx: check all niovs filled with dma addresses

Add a warning if io_populate_area_dma() can't fill in all net_iovs, it
should never happen.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/zcrx.c

@@ -77,6 +77,9 @@ static int io_populate_area_dma(struct io_zcrx_ifq *ifq,
 			niov_idx++;
 		}
 	}
+
+	if (WARN_ON_ONCE(niov_idx != area->nia.num_niovs))
+		return -EFAULT;
 	return 0;
 }