| 1 | /* |
| 2 | * splice io engine |
| 3 | * |
| 4 | */ |
| 5 | #include <stdio.h> |
| 6 | #include <stdlib.h> |
| 7 | #include <unistd.h> |
| 8 | #include <errno.h> |
| 9 | #include <assert.h> |
| 10 | #include <sys/poll.h> |
| 11 | #include "fio.h" |
| 12 | #include "os.h" |
| 13 | |
| 14 | struct spliceio_data { |
| 15 | struct io_u *last_io_u; |
| 16 | int pipe[2]; |
| 17 | }; |
| 18 | |
| 19 | static int fio_spliceio_sync(struct thread_data *td) |
| 20 | { |
| 21 | return fsync(td->fd); |
| 22 | } |
| 23 | |
| 24 | static int fio_spliceio_getevents(struct thread_data *td, int fio_unused min, |
| 25 | int max, struct timespec fio_unused *t) |
| 26 | { |
| 27 | assert(max <= 1); |
| 28 | |
| 29 | /* |
| 30 | * we can only have one finished io_u for sync io, since the depth |
| 31 | * is always 1 |
| 32 | */ |
| 33 | if (list_empty(&td->io_u_busylist)) |
| 34 | return 0; |
| 35 | |
| 36 | return 1; |
| 37 | } |
| 38 | |
| 39 | static struct io_u *fio_spliceio_event(struct thread_data *td, int event) |
| 40 | { |
| 41 | struct spliceio_data *sd = td->io_ops->data; |
| 42 | |
| 43 | assert(event == 0); |
| 44 | |
| 45 | return sd->last_io_u; |
| 46 | } |
| 47 | |
| 48 | /* |
| 49 | * For splice reading, we unfortunately cannot (yet) vmsplice the other way. |
| 50 | * So just splice the data from the file into the pipe, and use regular |
| 51 | * read to fill the buffer. Doesn't make a lot of sense, but... |
| 52 | */ |
| 53 | static int fio_splice_read(struct thread_data *td, struct io_u *io_u) |
| 54 | { |
| 55 | struct spliceio_data *sd = td->io_ops->data; |
| 56 | int ret, ret2, buflen; |
| 57 | off_t offset; |
| 58 | void *p; |
| 59 | |
| 60 | offset = io_u->offset; |
| 61 | buflen = io_u->buflen; |
| 62 | p = io_u->buf; |
| 63 | while (buflen) { |
| 64 | int this_len = buflen; |
| 65 | |
| 66 | if (this_len > SPLICE_DEF_SIZE) |
| 67 | this_len = SPLICE_DEF_SIZE; |
| 68 | |
| 69 | ret = splice(td->fd, &offset, sd->pipe[1], NULL, this_len, SPLICE_F_MORE); |
| 70 | if (ret < 0) { |
| 71 | if (errno == ENODATA || errno == EAGAIN) |
| 72 | continue; |
| 73 | |
| 74 | return errno; |
| 75 | } |
| 76 | |
| 77 | buflen -= ret; |
| 78 | |
| 79 | while (ret) { |
| 80 | ret2 = read(sd->pipe[0], p, ret); |
| 81 | if (ret2 < 0) |
| 82 | return errno; |
| 83 | |
| 84 | ret -= ret2; |
| 85 | p += ret2; |
| 86 | } |
| 87 | } |
| 88 | |
| 89 | return io_u->buflen; |
| 90 | } |
| 91 | |
| 92 | /* |
| 93 | * For splice writing, we can vmsplice our data buffer directly into a |
| 94 | * pipe and then splice that to a file. |
| 95 | */ |
| 96 | static int fio_splice_write(struct thread_data *td, struct io_u *io_u) |
| 97 | { |
| 98 | struct spliceio_data *sd = td->io_ops->data; |
| 99 | struct iovec iov[1] = { |
| 100 | { |
| 101 | .iov_base = io_u->buf, |
| 102 | .iov_len = io_u->buflen, |
| 103 | } |
| 104 | }; |
| 105 | struct pollfd pfd = { .fd = sd->pipe[1], .events = POLLOUT, }; |
| 106 | off_t off = io_u->offset; |
| 107 | int ret, ret2; |
| 108 | |
| 109 | while (iov[0].iov_len) { |
| 110 | if (poll(&pfd, 1, -1) < 0) |
| 111 | return errno; |
| 112 | |
| 113 | ret = vmsplice(sd->pipe[1], iov, 1, SPLICE_F_NONBLOCK); |
| 114 | if (ret < 0) |
| 115 | return errno; |
| 116 | |
| 117 | iov[0].iov_len -= ret; |
| 118 | iov[0].iov_base += ret; |
| 119 | |
| 120 | while (ret) { |
| 121 | ret2 = splice(sd->pipe[0], NULL, td->fd, &off, ret, 0); |
| 122 | if (ret2 < 0) |
| 123 | return errno; |
| 124 | |
| 125 | ret -= ret2; |
| 126 | } |
| 127 | } |
| 128 | |
| 129 | return io_u->buflen; |
| 130 | } |
| 131 | |
| 132 | static int fio_spliceio_queue(struct thread_data *td, struct io_u *io_u) |
| 133 | { |
| 134 | struct spliceio_data *sd = td->io_ops->data; |
| 135 | int ret; |
| 136 | |
| 137 | if (io_u->ddir == DDIR_READ) |
| 138 | ret = fio_splice_read(td, io_u); |
| 139 | else |
| 140 | ret = fio_splice_write(td, io_u); |
| 141 | |
| 142 | if ((unsigned int) ret != io_u->buflen) { |
| 143 | if (ret > 0) { |
| 144 | io_u->resid = io_u->buflen - ret; |
| 145 | io_u->error = ENODATA; |
| 146 | } else |
| 147 | io_u->error = errno; |
| 148 | } |
| 149 | |
| 150 | if (!io_u->error) |
| 151 | sd->last_io_u = io_u; |
| 152 | |
| 153 | return io_u->error; |
| 154 | } |
| 155 | |
| 156 | static void fio_spliceio_cleanup(struct thread_data *td) |
| 157 | { |
| 158 | struct spliceio_data *sd = td->io_ops->data; |
| 159 | |
| 160 | if (sd) { |
| 161 | close(sd->pipe[0]); |
| 162 | close(sd->pipe[1]); |
| 163 | free(sd); |
| 164 | td->io_ops->data = NULL; |
| 165 | } |
| 166 | } |
| 167 | |
| 168 | static int fio_spliceio_init(struct thread_data *td) |
| 169 | { |
| 170 | struct spliceio_data *sd = malloc(sizeof(*sd)); |
| 171 | |
| 172 | sd->last_io_u = NULL; |
| 173 | if (pipe(sd->pipe) < 0) { |
| 174 | td_verror(td, errno); |
| 175 | free(sd); |
| 176 | return 1; |
| 177 | } |
| 178 | |
| 179 | td->io_ops->data = sd; |
| 180 | return 0; |
| 181 | } |
| 182 | |
| 183 | struct ioengine_ops ioengine = { |
| 184 | .name = "splice", |
| 185 | .version = FIO_IOOPS_VERSION, |
| 186 | .init = fio_spliceio_init, |
| 187 | .queue = fio_spliceio_queue, |
| 188 | .getevents = fio_spliceio_getevents, |
| 189 | .event = fio_spliceio_event, |
| 190 | .cleanup = fio_spliceio_cleanup, |
| 191 | .sync = fio_spliceio_sync, |
| 192 | .flags = FIO_SYNCIO, |
| 193 | }; |