io_uring: add a few test tools

This adds two test programs in tools/io_uring/ that demonstrate both
the raw io_uring API (and all features) through a small benchmark
app, io_uring-bench, and the liburing exposed API in a simplified
cp(1) implementation through io_uring-cp.

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

1 files changed, 251 insertions, 0 deletions

diff --git a/tools/io_uring/io_uring-cp.c b/tools/io_uring/io_uring-cp.c
new file mode 100644
index 000000000000..633f65bb43a7
--- /dev/null
+++ b/tools/io_uring/io_uring-cp.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Simple test program that demonstrates a file copy through io_uring. This
+ * uses the API exposed by liburing.
+ *
+ * Copyright (C) 2018-2019 Jens Axboe
+ */
+#include <stdio.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <assert.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+
+#include "liburing.h"
+
+#define QD	64
+#define BS	(32*1024)
+
+static int infd, outfd;
+
+struct io_data {
+	int read;
+	off_t first_offset, offset;
+	size_t first_len;
+	struct iovec iov;
+};
+
+static int setup_context(unsigned entries, struct io_uring *ring)
+{
+	int ret;
+
+	ret = io_uring_queue_init(entries, ring, 0);
+	if (ret < 0) {
+		fprintf(stderr, "queue_init: %s\n", strerror(-ret));
+		return -1;
+	}
+
+	return 0;
+}
+
+static int get_file_size(int fd, off_t *size)
+{
+	struct stat st;
+
+	if (fstat(fd, &st) < 0)
+		return -1;
+	if (S_ISREG(st.st_mode)) {
+		*size = st.st_size;
+		return 0;
+	} else if (S_ISBLK(st.st_mode)) {
+		unsigned long long bytes;
+
+		if (ioctl(fd, BLKGETSIZE64, &bytes) != 0)
+			return -1;
+
+		*size = bytes;
+		return 0;
+	}
+
+	return -1;
+}
+
+static void queue_prepped(struct io_uring *ring, struct io_data *data)
+{
+	struct io_uring_sqe *sqe;
+
+	sqe = io_uring_get_sqe(ring);
+	assert(sqe);
+
+	if (data->read)
+		io_uring_prep_readv(sqe, infd, &data->iov, 1, data->offset);
+	else
+		io_uring_prep_writev(sqe, outfd, &data->iov, 1, data->offset);
+
+	io_uring_sqe_set_data(sqe, data);
+}
+
+static int queue_read(struct io_uring *ring, off_t size, off_t offset)
+{
+	struct io_uring_sqe *sqe;
+	struct io_data *data;
+
+	sqe = io_uring_get_sqe(ring);
+	if (!sqe)
+		return 1;
+
+	data = malloc(size + sizeof(*data));
+	data->read = 1;
+	data->offset = data->first_offset = offset;
+
+	data->iov.iov_base = data + 1;
+	data->iov.iov_len = size;
+	data->first_len = size;
+
+	io_uring_prep_readv(sqe, infd, &data->iov, 1, offset);
+	io_uring_sqe_set_data(sqe, data);
+	return 0;
+}
+
+static void queue_write(struct io_uring *ring, struct io_data *data)
+{
+	data->read = 0;
+	data->offset = data->first_offset;
+
+	data->iov.iov_base = data + 1;
+	data->iov.iov_len = data->first_len;
+
+	queue_prepped(ring, data);
+	io_uring_submit(ring);
+}
+
+static int copy_file(struct io_uring *ring, off_t insize)
+{
+	unsigned long reads, writes;
+	struct io_uring_cqe *cqe;
+	off_t write_left, offset;
+	int ret;
+
+	write_left = insize;
+	writes = reads = offset = 0;
+
+	while (insize || write_left) {
+		unsigned long had_reads;
+		int got_comp;
+
+		/*
+		 * Queue up as many reads as we can
+		 */
+		had_reads = reads;
+		while (insize) {
+			off_t this_size = insize;
+
+			if (reads + writes >= QD)
+				break;
+			if (this_size > BS)
+				this_size = BS;
+			else if (!this_size)
+				break;
+
+			if (queue_read(ring, this_size, offset))
+				break;
+
+			insize -= this_size;
+			offset += this_size;
+			reads++;
+		}
+
+		if (had_reads != reads) {
+			ret = io_uring_submit(ring);
+			if (ret < 0) {
+				fprintf(stderr, "io_uring_submit: %s\n", strerror(-ret));
+				break;
+			}
+		}
+
+		/*
+		 * Queue is full at this point. Find at least one completion.
+		 */
+		got_comp = 0;
+		while (write_left) {
+			struct io_data *data;
+
+			if (!got_comp) {
+				ret = io_uring_wait_completion(ring, &cqe);
+				got_comp = 1;
+			} else
+				ret = io_uring_get_completion(ring, &cqe);
+			if (ret < 0) {
+				fprintf(stderr, "io_uring_get_completion: %s\n",
+							strerror(-ret));
+				return 1;
+			}
+			if (!cqe)
+				break;
+
+			data = (struct io_data *) (uintptr_t) cqe->user_data;
+			if (cqe->res < 0) {
+				if (cqe->res == -EAGAIN) {
+					queue_prepped(ring, data);
+					continue;
+				}
+				fprintf(stderr, "cqe failed: %s\n",
+						strerror(-cqe->res));
+				return 1;
+			} else if ((size_t) cqe->res != data->iov.iov_len) {
+				/* Short read/write, adjust and requeue */
+				data->iov.iov_base += cqe->res;
+				data->iov.iov_len -= cqe->res;
+				data->offset += cqe->res;
+				queue_prepped(ring, data);
+				continue;
+			}
+
+			/*
+			 * All done. if write, nothing else to do. if read,
+			 * queue up corresponding write.
+			 */
+			if (data->read) {
+				queue_write(ring, data);
+				write_left -= data->first_len;
+				reads--;
+				writes++;
+			} else {
+				free(data);
+				writes--;
+			}
+		}
+	}
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	struct io_uring ring;
+	off_t insize;
+	int ret;
+
+	if (argc < 3) {
+		printf("%s: infile outfile\n", argv[0]);
+		return 1;
+	}
+
+	infd = open(argv[1], O_RDONLY);
+	if (infd < 0) {
+		perror("open infile");
+		return 1;
+	}
+	outfd = open(argv[2], O_WRONLY | O_CREAT | O_TRUNC, 0644);
+	if (outfd < 0) {
+		perror("open outfile");
+		return 1;
+	}
+
+	if (setup_context(QD, &ring))
+		return 1;
+	if (get_file_size(infd, &insize))
+		return 1;
+
+	ret = copy_file(&ring, insize);
+
+	close(infd);
+	close(outfd);
+	io_uring_queue_exit(&ring);
+	return ret;
+}