test/open-direct-pick.c: add test case for open direct with alloc

Test case that tests the basic functionality of openat with direct
descriptors and asking io_uring to allocate the descriptors.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

test/Makefile

@@ -104,6 +104,7 @@ test_srcs := \
 	openat2.c \
 	open-close.c \
 	open-direct-link.c \
+	open-direct-pick.c \
 	personality.c \
 	pipe-eof.c \
 	pipe-reuse.c \

test/open-direct-pick.c

@@ -0,0 +1,180 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Description: run various openat(2) tests
+ *
+ */
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <limits.h>
+
+#include "helpers.h"
+#include "liburing.h"
+
+#define FDS	800
+
+static int no_direct_pick;
+
+static int submit_wait(struct io_uring *ring)
+{
+	struct io_uring_cqe *cqe;
+	int ret;
+
+	ret = io_uring_submit(ring);
+	if (ret <= 0) {
+		fprintf(stderr, "sqe submit failed: %d\n", ret);
+		return 1;
+	}
+	ret = io_uring_wait_cqe(ring, &cqe);
+	if (ret < 0) {
+		fprintf(stderr, "wait completion %d\n", ret);
+		return 1;
+	}
+
+	ret = cqe->res;
+	io_uring_cqe_seen(ring, cqe);
+	return ret;
+}
+
+static inline int try_close(struct io_uring *ring, int slot)
+{
+	struct io_uring_sqe *sqe;
+
+	sqe = io_uring_get_sqe(ring);
+	io_uring_prep_close_direct(sqe, slot);
+	return submit_wait(ring);
+}
+
+static int do_opens(struct io_uring *ring, const char *path, int nr,
+		    int expect_enfile)
+{
+	struct io_uring_cqe *cqe;
+	struct io_uring_sqe *sqe;
+	int i, ret;
+
+	for (i = 0; i < nr; i++) {
+		sqe = io_uring_get_sqe(ring);
+		if (!sqe) {
+			fprintf(stderr, "get sqe failed\n");
+			goto err;
+		}
+		io_uring_prep_openat_direct(sqe, -1, path, O_RDONLY, 0, 0);
+		sqe->file_index = UINT_MAX;
+
+		ret = io_uring_submit(ring);
+		if (ret <= 0) {
+			fprintf(stderr, "sqe submit failed: %d\n", ret);
+			goto err;
+		}
+	}
+
+	for (i = 0; i < nr; i++) {
+		ret = io_uring_wait_cqe(ring, &cqe);
+		if (ret < 0) {
+			fprintf(stderr, "wait completion %d\n", ret);
+			goto err;
+		}
+		ret = cqe->res;
+		if (ret < 0) {
+			if (!expect_enfile || ret != -ENFILE) {
+				printf("open=%d, %d\n", cqe->res, i);
+				goto err;
+			}
+			if (!i && ret == -EINVAL) {
+				no_direct_pick = 1;
+				return 0;
+			}
+		}
+		io_uring_cqe_seen(ring, cqe);
+	}
+	return 0;
+err:
+	return 1;
+}
+
+static int test_openat(struct io_uring *ring, const char *path)
+{
+	int ret, i;
+
+	/* open all */
+	ret = do_opens(ring, path, FDS, 0);
+	if (ret)
+		goto err;
+	if (no_direct_pick)
+		return 0;
+
+	/* now close 100 randomly */
+	for (i = 0; i < 100; i++) {
+		do {
+			int slot = rand() % FDS;
+			ret = try_close(ring, slot);
+			if (ret == -EBADF)
+				continue;
+			break;
+		} while (1);
+	}
+
+	/* opening 100 should work, we closed 100 */
+	ret = do_opens(ring, path, 100, 0);
+	if (ret)
+		goto err;
+
+	/* we should be full now, expect -ENFILE */
+	ret = do_opens(ring, path, 1, 1);
+	if (ret)
+		goto err;
+
+	return ret;
+err:
+	fprintf(stderr,"%s: err=%d\n", __FUNCTION__, ret);
+	return -1;
+}
+
+int main(int argc, char *argv[])
+{
+	struct io_uring ring;
+	const char *path;
+	int ret;
+
+	if (argc > 1)
+		return 0;
+
+	ret = io_uring_queue_init(8, &ring, 0);
+	if (ret) {
+		fprintf(stderr, "ring setup failed\n");
+		return 1;
+	}
+
+	ret = io_uring_register_files_sparse(&ring, FDS);
+	if (ret ) {
+		if (ret != -EINVAL) {
+			fprintf(stderr, "Sparse file registration failed\n");
+			return 1;
+		}
+		/* skip, kernel doesn't support sparse file array */
+		return 0;
+	}
+
+	path = "/tmp/.open.close";
+	t_create_file(path, 4096);
+
+	ret = test_openat(&ring, path);
+	if (ret < 0) {
+		if (ret == -EINVAL) {
+			fprintf(stdout, "Open not supported, skipping\n");
+			goto done;
+		}
+		fprintf(stderr, "test_openat absolute failed: %d\n", ret);
+		goto err;
+	}
+
+done:
+	unlink(path);
+	return 0;
+err:
+	unlink(path);
+	return 1;
+}