summaryrefslogtreecommitdiff
path: root/examples/link-cp.c
blob: 6fa54ac004a211bff6dbdb0fbbcbddfa4cbd937d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
/* SPDX-License-Identifier: MIT */
/*
 * Very basic proof-of-concept for doing a copy with linked SQEs. Needs a
 * bit of error handling and short read love.
 */
#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/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include "liburing.h"

#define QD	64
#define BS	(32*1024)

struct io_data {
	size_t offset;
	int index;
	struct iovec iov;
};

static int infd, outfd;
static unsigned inflight;

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_rw_pair(struct io_uring *ring, off_t size, off_t offset)
{
	struct io_uring_sqe *sqe;
	struct io_data *data;
	void *ptr;

	ptr = malloc(size + sizeof(*data));
	data = ptr + size;
	data->index = 0;
	data->offset = offset;
	data->iov.iov_base = ptr;
	data->iov.iov_len = size;

	sqe = io_uring_get_sqe(ring);
	io_uring_prep_readv(sqe, infd, &data->iov, 1, offset);
	sqe->flags |= IOSQE_IO_LINK;
	io_uring_sqe_set_data(sqe, data);

	sqe = io_uring_get_sqe(ring);
	io_uring_prep_writev(sqe, outfd, &data->iov, 1, offset);
	io_uring_sqe_set_data(sqe, data);
}

static int handle_cqe(struct io_uring *ring, struct io_uring_cqe *cqe)
{
	struct io_data *data = io_uring_cqe_get_data(cqe);
	int ret = 0;

	data->index++;

	if (cqe->res < 0) {
		if (cqe->res == -ECANCELED) {
			queue_rw_pair(ring, BS, data->offset);
			inflight += 2;
		} else {
			printf("cqe error: %s\n", strerror(cqe->res));
			ret = 1;
		}
	}

	if (data->index == 2) {
		void *ptr = (void *) data - data->iov.iov_len;

		free(ptr);
	}
	io_uring_cqe_seen(ring, cqe);
	return ret;
}

static int copy_file(struct io_uring *ring, off_t insize)
{
	struct io_uring_cqe *cqe;
	size_t this_size;
	off_t offset;

	offset = 0;
	while (insize) {
		int has_inflight = inflight;
		int depth;

		while (insize && inflight < QD) {
			this_size = BS;
			if (this_size > insize)
				this_size = insize;
			queue_rw_pair(ring, this_size, offset);
			offset += this_size;
			insize -= this_size;
			inflight += 2;
		}

		if (has_inflight != inflight)
			io_uring_submit(ring);

		if (insize)
			depth = QD;
		else
			depth = 1;
		while (inflight >= depth) {
			int ret;

			ret = io_uring_wait_cqe(ring, &cqe);
			if (ret < 0) {
				printf("wait cqe: %s\n", strerror(ret));
				return 1;
			}
			if (handle_cqe(ring, cqe))
				return 1;
			inflight--;
		}
	}

	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;
}