[PATCH liburing] add a test for async reads with buffer_select

[Dylan Yudaken <dylany@fb.com>]

Async reads had a bug with buffer selection.
Add a regression test for this.
It fails without the kernel commit: "io_uring: fix provided buffer import"

Signed-off-by: Dylan Yudaken <dylany@fb.com>
---
 test/read-write.c | 101 +++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 95 insertions(+), 6 deletions(-)

diff --git a/test/read-write.c b/test/read-write.c
index 3951a64..eadeb78 100644
--- a/test/read-write.c
+++ b/test/read-write.c
@@ -428,25 +428,28 @@ static int test_buf_select_short(const char *filename, int nonvec)
 	return ret;
 }
 
-static int provide_buffers_iovec(struct io_uring *ring, int bgid)
+static int provide_buffers_iovec(struct io_uring *ring, int bgid, int count)
 {
 	struct io_uring_sqe *sqe;
 	struct io_uring_cqe *cqe;
 	int i, ret;
 
-	for (i = 0; i < BUFFERS; i++) {
+	if (count <= 0)
+		count = BUFFERS;
+
+	for (i = 0; i < count; i++) {
 		sqe = io_uring_get_sqe(ring);
 		io_uring_prep_provide_buffers(sqe, vecs[i].iov_base,
 						vecs[i].iov_len, 1, bgid, i);
 	}
 
 	ret = io_uring_submit(ring);
-	if (ret != BUFFERS) {
+	if (ret != count) {
 		fprintf(stderr, "submit: %d\n", ret);
 		return -1;
 	}
 
-	for (i = 0; i < BUFFERS; i++) {
+	for (i = 0; i < count; i++) {
 		ret = io_uring_wait_cqe(ring, &cqe);
 		if (ret) {
 			fprintf(stderr, "wait_cqe=%d\n", ret);
@@ -462,6 +465,86 @@ static int provide_buffers_iovec(struct io_uring *ring, int bgid)
 	return 0;
 }
 
+static int test_buf_select_pipe(void)
+{
+	struct io_uring_sqe *sqe;
+	struct io_uring_cqe *cqe;
+	struct io_uring ring;
+	int ret, i;
+	int fds[2];
+
+	if (no_buf_select)
+		return 0;
+
+	ret = io_uring_queue_init(64, &ring, 0);
+	if (ret) {
+		fprintf(stderr, "ring create failed: %d\n", ret);
+		return 1;
+	}
+
+	ret = provide_buffers_iovec(&ring, 0, 4);
+	if (ret) {
+		fprintf(stderr, "provide buffers failed: %d\n", ret);
+		return 1;
+	}
+
+	ret = pipe(fds);
+	if (ret) {
+		fprintf(stderr, "pipe failed: %d\n", ret);
+		return 1;
+	}
+
+	for (i = 0; i < 5; i++) {
+		sqe = io_uring_get_sqe(&ring);
+		io_uring_prep_read(sqe, fds[0], NULL, 1 /* max read 1 per go */, -1);
+		sqe->flags |= IOSQE_BUFFER_SELECT;
+		sqe->buf_group = 0;
+	}
+	io_uring_submit(&ring);
+
+	ret = write(fds[1], "01234", 5);
+	if (ret != 5) {
+		fprintf(stderr, "pipe write failed %d\n", ret);
+		return 1;
+	}
+
+	for (i = 0; i < 5; i++) {
+		const char *buff;
+
+		if (io_uring_wait_cqe(&ring, &cqe)) {
+			fprintf(stderr, "bad wait %d\n", i);
+			return 1;
+		}
+		if (i == 4) {
+			if (cqe->res != -ENOBUFS) {
+				fprintf(stderr, "expected failure %d\n", cqe->res);
+				return 1;
+			}
+			continue;
+		}
+		if (cqe->res != 1) {
+			fprintf(stderr, "expected read %d\n", cqe->res);
+			return 1;
+		}
+		if (!(cqe->flags & IORING_CQE_F_BUFFER)) {
+			fprintf(stderr, "no buffer %d\n", cqe->res);
+			return 1;
+		}
+		buff = vecs[cqe->flags >> 16].iov_base;
+		if (*buff != '0' + i) {
+			fprintf(stderr, "%d: expected %c, got %c\n", i, '0' + i, *buff);
+			return 1;
+		}
+		io_uring_cqe_seen(&ring, cqe);
+	}
+
+
+	close(fds[0]);
+	close(fds[1]);
+	io_uring_queue_exit(&ring);
+	return 0;
+}
+
 static int test_buf_select(const char *filename, int nonvec)
 {
 	struct io_uring_probe *p;
@@ -497,7 +580,7 @@ static int test_buf_select(const char *filename, int nonvec)
 	for (i = 0; i < BUFFERS; i++)
 		memset(vecs[i].iov_base, 0x55, vecs[i].iov_len);
 
-	ret = provide_buffers_iovec(&ring, 1);
+	ret = provide_buffers_iovec(&ring, 1, -1);
 	if (ret)
 		return ret;
 
@@ -523,7 +606,7 @@ static int test_rem_buf(int batch, int sqe_flags)
 		return 1;
 	}
 
-	ret = provide_buffers_iovec(&ring, bgid);
+	ret = provide_buffers_iovec(&ring, bgid, -1);
 	if (ret)
 		return ret;
 
@@ -791,6 +874,12 @@ int main(int argc, char *argv[])
 		goto err;
 	}
 
+	ret = test_buf_select_pipe();
+	if (ret) {
+		fprintf(stderr, "test_buf_select_pipe failed\n");
+		goto err;
+	}
+
 	ret = test_eventfd_read();
 	if (ret) {
 		fprintf(stderr, "test_eventfd_read failed\n");

base-commit: 70e11b3d79714c287c1a03e96eddd957474901dd
-- 
2.30.2