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/* 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 int 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, data->iov.iov_len, 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;
off_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;
}
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