blob: 28e1fb04efa79f6d99a695aff0b1fe8fd1b62379 [file] [log] [blame]
/*
* splice engine
*
* IO engine that transfers data by doing splices to/from pipes and
* the files.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <assert.h>
#include <sys/poll.h>
#include <sys/mman.h>
#include "../fio.h"
#ifdef FIO_HAVE_SPLICE
struct spliceio_data {
int pipe[2];
int vmsplice_to_user;
int vmsplice_to_user_map;
};
/*
* vmsplice didn't use to support splicing to user space, this is the old
* variant of getting that job done. Doesn't make a lot of sense, but it
* uses splices to move data from the source into a pipe.
*/
static int fio_splice_read_old(struct thread_data *td, struct io_u *io_u)
{
struct spliceio_data *sd = td->io_ops->data;
struct fio_file *f = io_u->file;
int ret, ret2, buflen;
off_t offset;
void *p;
offset = io_u->offset;
buflen = io_u->xfer_buflen;
p = io_u->xfer_buf;
while (buflen) {
int this_len = buflen;
if (this_len > SPLICE_DEF_SIZE)
this_len = SPLICE_DEF_SIZE;
ret = splice(f->fd, &offset, sd->pipe[1], NULL, this_len, SPLICE_F_MORE);
if (ret < 0) {
if (errno == ENODATA || errno == EAGAIN)
continue;
return -errno;
}
buflen -= ret;
while (ret) {
ret2 = read(sd->pipe[0], p, ret);
if (ret2 < 0)
return -errno;
ret -= ret2;
p += ret2;
}
}
return io_u->xfer_buflen;
}
/*
* We can now vmsplice into userspace, so do the transfer by splicing into
* a pipe and vmsplicing that into userspace.
*/
static int fio_splice_read(struct thread_data *td, struct io_u *io_u)
{
struct spliceio_data *sd = td->io_ops->data;
struct fio_file *f = io_u->file;
struct iovec iov;
int ret , buflen, mmap_len;
off_t offset;
void *p, *map;
ret = 0;
offset = io_u->offset;
mmap_len = buflen = io_u->xfer_buflen;
if (sd->vmsplice_to_user_map) {
map = mmap(io_u->xfer_buf, buflen, PROT_READ, MAP_PRIVATE|OS_MAP_ANON, 0, 0);
if (map == MAP_FAILED) {
td_verror(td, errno, "mmap io_u");
return -1;
}
p = map;
} else {
map = NULL;
p = io_u->xfer_buf;
}
while (buflen) {
int this_len = buflen;
int flags = 0;
if (this_len > SPLICE_DEF_SIZE) {
this_len = SPLICE_DEF_SIZE;
flags = SPLICE_F_MORE;
}
ret = splice(f->fd, &offset, sd->pipe[1], NULL, this_len,flags);
if (ret < 0) {
if (errno == ENODATA || errno == EAGAIN)
continue;
td_verror(td, errno, "splice-from-fd");
break;
}
buflen -= ret;
iov.iov_base = p;
iov.iov_len = ret;
while (iov.iov_len) {
ret = vmsplice(sd->pipe[0], &iov, 1, SPLICE_F_MOVE);
if (ret < 0) {
if (errno == EFAULT &&
sd->vmsplice_to_user_map) {
sd->vmsplice_to_user_map = 0;
munmap(map, mmap_len);
map = NULL;
p = io_u->xfer_buf;
iov.iov_base = p;
continue;
}
if (errno == EBADF) {
ret = -EBADF;
break;
}
td_verror(td, errno, "vmsplice");
break;
} else if (!ret) {
td_verror(td, ENODATA, "vmsplice");
ret = -1;
break;
}
iov.iov_len -= ret;
iov.iov_base += ret;
p += ret;
}
if (ret < 0)
break;
}
if (sd->vmsplice_to_user_map && munmap(map, mmap_len) < 0) {
td_verror(td, errno, "munnap io_u");
return -1;
}
if (ret < 0)
return ret;
return io_u->xfer_buflen;
}
/*
* For splice writing, we can vmsplice our data buffer directly into a
* pipe and then splice that to a file.
*/
static int fio_splice_write(struct thread_data *td, struct io_u *io_u)
{
struct spliceio_data *sd = td->io_ops->data;
struct iovec iov = {
.iov_base = io_u->xfer_buf,
.iov_len = io_u->xfer_buflen,
};
struct pollfd pfd = { .fd = sd->pipe[1], .events = POLLOUT, };
struct fio_file *f = io_u->file;
off_t off = io_u->offset;
int ret, ret2;
while (iov.iov_len) {
if (poll(&pfd, 1, -1) < 0)
return errno;
ret = vmsplice(sd->pipe[1], &iov, 1, SPLICE_F_NONBLOCK);
if (ret < 0)
return -errno;
iov.iov_len -= ret;
iov.iov_base += ret;
while (ret) {
ret2 = splice(sd->pipe[0], NULL, f->fd, &off, ret, 0);
if (ret2 < 0)
return -errno;
ret -= ret2;
}
}
return io_u->xfer_buflen;
}
static int fio_spliceio_queue(struct thread_data *td, struct io_u *io_u)
{
struct spliceio_data *sd = td->io_ops->data;
int uninitialized_var(ret);
fio_ro_check(td, io_u);
if (io_u->ddir == DDIR_READ) {
if (sd->vmsplice_to_user) {
ret = fio_splice_read(td, io_u);
/*
* This kernel doesn't support vmsplice to user
* space. Reset the vmsplice_to_user flag, so that
* we retry below and don't hit this path again.
*/
if (ret == -EBADF)
sd->vmsplice_to_user = 0;
}
if (!sd->vmsplice_to_user)
ret = fio_splice_read_old(td, io_u);
} else if (io_u->ddir == DDIR_WRITE)
ret = fio_splice_write(td, io_u);
else
ret = fsync(io_u->file->fd);
if (ret != (int) io_u->xfer_buflen) {
if (ret >= 0) {
io_u->resid = io_u->xfer_buflen - ret;
io_u->error = 0;
return FIO_Q_COMPLETED;
} else
io_u->error = errno;
}
if (io_u->error) {
td_verror(td, io_u->error, "xfer");
if (io_u->error == EINVAL)
log_err("fio: looks like splice doesn't work on this"
" file system\n");
}
return FIO_Q_COMPLETED;
}
static void fio_spliceio_cleanup(struct thread_data *td)
{
struct spliceio_data *sd = td->io_ops->data;
if (sd) {
close(sd->pipe[0]);
close(sd->pipe[1]);
free(sd);
}
}
static int fio_spliceio_init(struct thread_data *td)
{
struct spliceio_data *sd = malloc(sizeof(*sd));
if (pipe(sd->pipe) < 0) {
td_verror(td, errno, "pipe");
free(sd);
return 1;
}
/*
* Assume this work, we'll reset this if it doesn't
*/
sd->vmsplice_to_user = 1;
/*
* Works with "real" vmsplice to user, eg mapping pages directly.
* Reset if we fail.
*/
sd->vmsplice_to_user_map = 1;
/*
* And if vmsplice_to_user works, we definitely need aligned
* buffers. Just set ->odirect to force that.
*/
if (td_read(td))
td->o.odirect = 1;
td->io_ops->data = sd;
return 0;
}
static struct ioengine_ops ioengine = {
.name = "splice",
.version = FIO_IOOPS_VERSION,
.init = fio_spliceio_init,
.queue = fio_spliceio_queue,
.cleanup = fio_spliceio_cleanup,
.open_file = generic_open_file,
.close_file = generic_close_file,
.get_file_size = generic_get_file_size,
.flags = FIO_SYNCIO,
};
#else /* FIO_HAVE_SPLICE */
/*
* When we have a proper configure system in place, we simply wont build
* and install this io engine. For now install a crippled version that
* just complains and fails to load.
*/
static int fio_spliceio_init(struct thread_data fio_unused *td)
{
fprintf(stderr, "fio: splice not available\n");
return 1;
}
static struct ioengine_ops ioengine = {
.name = "splice",
.version = FIO_IOOPS_VERSION,
.init = fio_spliceio_init,
};
#endif
static void fio_init fio_spliceio_register(void)
{
register_ioengine(&ioengine);
}
static void fio_exit fio_spliceio_unregister(void)
{
unregister_ioengine(&ioengine);
}