Function test_read_overflow_refill

test/buf-ring-stress.c:208–351

* Test: submit more reads than available buffers. Excess reads should * fail with -ENOBUFS. Then refill and retry. */

 * fail with -ENOBUFS. Then refill and retry.
 */
static int test_read_overflow_refill(void)
{
	struct io_uring ring;
	struct io_uring_buf_ring *br;
	struct io_uring_sqe *sqe;
	struct io_uring_cqe *cqe;
	void *buf_base;
	const char *fname = ".buf-ring-overflow-tmp";
	int fd, ret;
	int nr_success = 0, nr_enobufs = 0;

	ret = io_uring_queue_init(32, &ring, 0);
	if (ret) {
		fprintf(stderr, "ring setup: %d\n", ret);
		return T_EXIT_FAIL;
	}

	br = io_uring_setup_buf_ring(&ring, NR_BUFS, BGID, 0, &ret);
	if (!br) {
		if (ret == -EINVAL || ret == -ENOENT) {
			io_uring_queue_exit(&ring);
			return T_EXIT_SKIP;
		}
		fprintf(stderr, "buf ring setup: %d\n", ret);
		io_uring_queue_exit(&ring);
		return T_EXIT_FAIL;
	}

	buf_base = malloc(NR_BUFS * BUF_SIZE);
	if (!buf_base)
		goto err;

	/* Create test file */
	t_create_file(fname, NR_BUFS * BUF_SIZE * 4);
	fd = open(fname, O_RDONLY);
	if (fd < 0) {
		perror("open");
		goto err;
	}

	/* Provide only NR_BUFS buffers */
	provide_buffers(br, buf_base, NR_BUFS, BUF_SIZE);

	/* Submit more reads than we have buffers */
	for (int i = 0; i < NR_BUFS * 2; i++) {
		sqe = io_uring_get_sqe(&ring);
		io_uring_prep_read(sqe, fd, NULL, BUF_SIZE, i * BUF_SIZE);
		sqe->flags |= IOSQE_BUFFER_SELECT;
		sqe->buf_group = BGID;
		sqe->user_data = i;
	}

	ret = io_uring_submit(&ring);
	if (ret != NR_BUFS * 2) {
		fprintf(stderr, "submit: %d\n", ret);
		goto err_file;
	}