| 1 | /* |
| 2 | * splice engine |
| 3 | * |
| 4 | * IO engine that transfers data by doing splices to/from pipes and |
| 5 | * the files. |
| 6 | * |
| 7 | */ |
| 8 | #include <stdio.h> |
| 9 | #include <stdlib.h> |
| 10 | #include <unistd.h> |
| 11 | #include <errno.h> |
| 12 | #include <poll.h> |
| 13 | #include <sys/mman.h> |
| 14 | |
| 15 | #include "../fio.h" |
| 16 | |
| 17 | struct spliceio_data { |
| 18 | int pipe[2]; |
| 19 | int vmsplice_to_user; |
| 20 | int vmsplice_to_user_map; |
| 21 | }; |
| 22 | |
| 23 | /* |
| 24 | * vmsplice didn't use to support splicing to user space, this is the old |
| 25 | * variant of getting that job done. Doesn't make a lot of sense, but it |
| 26 | * uses splices to move data from the source into a pipe. |
| 27 | */ |
| 28 | static int fio_splice_read_old(struct thread_data *td, struct io_u *io_u) |
| 29 | { |
| 30 | struct spliceio_data *sd = td->io_ops_data; |
| 31 | struct fio_file *f = io_u->file; |
| 32 | int ret, ret2, buflen; |
| 33 | off_t offset; |
| 34 | char *p; |
| 35 | |
| 36 | offset = io_u->offset; |
| 37 | buflen = io_u->xfer_buflen; |
| 38 | p = io_u->xfer_buf; |
| 39 | while (buflen) { |
| 40 | int this_len = buflen; |
| 41 | |
| 42 | if (this_len > SPLICE_DEF_SIZE) |
| 43 | this_len = SPLICE_DEF_SIZE; |
| 44 | |
| 45 | ret = splice(f->fd, &offset, sd->pipe[1], NULL, this_len, SPLICE_F_MORE); |
| 46 | if (ret < 0) { |
| 47 | if (errno == ENODATA || errno == EAGAIN) |
| 48 | continue; |
| 49 | |
| 50 | return -errno; |
| 51 | } |
| 52 | |
| 53 | buflen -= ret; |
| 54 | |
| 55 | while (ret) { |
| 56 | ret2 = read(sd->pipe[0], p, ret); |
| 57 | if (ret2 < 0) |
| 58 | return -errno; |
| 59 | |
| 60 | ret -= ret2; |
| 61 | p += ret2; |
| 62 | } |
| 63 | } |
| 64 | |
| 65 | return io_u->xfer_buflen; |
| 66 | } |
| 67 | |
| 68 | /* |
| 69 | * We can now vmsplice into userspace, so do the transfer by splicing into |
| 70 | * a pipe and vmsplicing that into userspace. |
| 71 | */ |
| 72 | static int fio_splice_read(struct thread_data *td, struct io_u *io_u) |
| 73 | { |
| 74 | struct spliceio_data *sd = td->io_ops_data; |
| 75 | struct fio_file *f = io_u->file; |
| 76 | struct iovec iov; |
| 77 | int ret , buflen, mmap_len; |
| 78 | off_t offset; |
| 79 | void *map; |
| 80 | char *p; |
| 81 | |
| 82 | ret = 0; |
| 83 | offset = io_u->offset; |
| 84 | mmap_len = buflen = io_u->xfer_buflen; |
| 85 | |
| 86 | if (sd->vmsplice_to_user_map) { |
| 87 | map = mmap(io_u->xfer_buf, buflen, PROT_READ, MAP_PRIVATE|OS_MAP_ANON, 0, 0); |
| 88 | if (map == MAP_FAILED) { |
| 89 | td_verror(td, errno, "mmap io_u"); |
| 90 | return -1; |
| 91 | } |
| 92 | |
| 93 | p = map; |
| 94 | } else { |
| 95 | map = NULL; |
| 96 | p = io_u->xfer_buf; |
| 97 | } |
| 98 | |
| 99 | while (buflen) { |
| 100 | int this_len = buflen; |
| 101 | int flags = 0; |
| 102 | |
| 103 | if (this_len > SPLICE_DEF_SIZE) { |
| 104 | this_len = SPLICE_DEF_SIZE; |
| 105 | flags = SPLICE_F_MORE; |
| 106 | } |
| 107 | |
| 108 | ret = splice(f->fd, &offset, sd->pipe[1], NULL, this_len,flags); |
| 109 | if (ret < 0) { |
| 110 | if (errno == ENODATA || errno == EAGAIN) |
| 111 | continue; |
| 112 | |
| 113 | td_verror(td, errno, "splice-from-fd"); |
| 114 | break; |
| 115 | } |
| 116 | |
| 117 | buflen -= ret; |
| 118 | iov.iov_base = p; |
| 119 | iov.iov_len = ret; |
| 120 | |
| 121 | while (iov.iov_len) { |
| 122 | ret = vmsplice(sd->pipe[0], &iov, 1, SPLICE_F_MOVE); |
| 123 | if (ret < 0) { |
| 124 | if (errno == EFAULT && |
| 125 | sd->vmsplice_to_user_map) { |
| 126 | sd->vmsplice_to_user_map = 0; |
| 127 | munmap(map, mmap_len); |
| 128 | map = NULL; |
| 129 | p = io_u->xfer_buf; |
| 130 | iov.iov_base = p; |
| 131 | continue; |
| 132 | } |
| 133 | if (errno == EBADF) { |
| 134 | ret = -EBADF; |
| 135 | break; |
| 136 | } |
| 137 | td_verror(td, errno, "vmsplice"); |
| 138 | break; |
| 139 | } else if (!ret) { |
| 140 | td_verror(td, ENODATA, "vmsplice"); |
| 141 | ret = -1; |
| 142 | break; |
| 143 | } |
| 144 | |
| 145 | iov.iov_len -= ret; |
| 146 | iov.iov_base += ret; |
| 147 | p += ret; |
| 148 | } |
| 149 | if (ret < 0) |
| 150 | break; |
| 151 | } |
| 152 | |
| 153 | if (sd->vmsplice_to_user_map && munmap(map, mmap_len) < 0) { |
| 154 | td_verror(td, errno, "munnap io_u"); |
| 155 | return -1; |
| 156 | } |
| 157 | if (ret < 0) |
| 158 | return ret; |
| 159 | |
| 160 | return io_u->xfer_buflen; |
| 161 | } |
| 162 | |
| 163 | /* |
| 164 | * For splice writing, we can vmsplice our data buffer directly into a |
| 165 | * pipe and then splice that to a file. |
| 166 | */ |
| 167 | static int fio_splice_write(struct thread_data *td, struct io_u *io_u) |
| 168 | { |
| 169 | struct spliceio_data *sd = td->io_ops_data; |
| 170 | struct iovec iov = { |
| 171 | .iov_base = io_u->xfer_buf, |
| 172 | .iov_len = io_u->xfer_buflen, |
| 173 | }; |
| 174 | struct pollfd pfd = { .fd = sd->pipe[1], .events = POLLOUT, }; |
| 175 | struct fio_file *f = io_u->file; |
| 176 | off_t off = io_u->offset; |
| 177 | int ret, ret2; |
| 178 | |
| 179 | while (iov.iov_len) { |
| 180 | if (poll(&pfd, 1, -1) < 0) |
| 181 | return errno; |
| 182 | |
| 183 | ret = vmsplice(sd->pipe[1], &iov, 1, SPLICE_F_NONBLOCK); |
| 184 | if (ret < 0) |
| 185 | return -errno; |
| 186 | |
| 187 | iov.iov_len -= ret; |
| 188 | iov.iov_base += ret; |
| 189 | |
| 190 | while (ret) { |
| 191 | ret2 = splice(sd->pipe[0], NULL, f->fd, &off, ret, 0); |
| 192 | if (ret2 < 0) |
| 193 | return -errno; |
| 194 | |
| 195 | ret -= ret2; |
| 196 | } |
| 197 | } |
| 198 | |
| 199 | return io_u->xfer_buflen; |
| 200 | } |
| 201 | |
| 202 | static enum fio_q_status fio_spliceio_queue(struct thread_data *td, |
| 203 | struct io_u *io_u) |
| 204 | { |
| 205 | struct spliceio_data *sd = td->io_ops_data; |
| 206 | int ret = 0; |
| 207 | |
| 208 | fio_ro_check(td, io_u); |
| 209 | |
| 210 | if (io_u->ddir == DDIR_READ) { |
| 211 | if (sd->vmsplice_to_user) { |
| 212 | ret = fio_splice_read(td, io_u); |
| 213 | /* |
| 214 | * This kernel doesn't support vmsplice to user |
| 215 | * space. Reset the vmsplice_to_user flag, so that |
| 216 | * we retry below and don't hit this path again. |
| 217 | */ |
| 218 | if (ret == -EBADF) |
| 219 | sd->vmsplice_to_user = 0; |
| 220 | } |
| 221 | if (!sd->vmsplice_to_user) |
| 222 | ret = fio_splice_read_old(td, io_u); |
| 223 | } else if (io_u->ddir == DDIR_WRITE) |
| 224 | ret = fio_splice_write(td, io_u); |
| 225 | else if (io_u->ddir == DDIR_TRIM) |
| 226 | ret = do_io_u_trim(td, io_u); |
| 227 | else |
| 228 | ret = do_io_u_sync(td, io_u); |
| 229 | |
| 230 | if (ret != (int) io_u->xfer_buflen) { |
| 231 | if (ret >= 0) { |
| 232 | io_u->resid = io_u->xfer_buflen - ret; |
| 233 | io_u->error = 0; |
| 234 | return FIO_Q_COMPLETED; |
| 235 | } else |
| 236 | io_u->error = errno; |
| 237 | } |
| 238 | |
| 239 | if (io_u->error) { |
| 240 | td_verror(td, io_u->error, "xfer"); |
| 241 | if (io_u->error == EINVAL) |
| 242 | log_err("fio: looks like splice doesn't work on this" |
| 243 | " file system\n"); |
| 244 | } |
| 245 | |
| 246 | return FIO_Q_COMPLETED; |
| 247 | } |
| 248 | |
| 249 | static void fio_spliceio_cleanup(struct thread_data *td) |
| 250 | { |
| 251 | struct spliceio_data *sd = td->io_ops_data; |
| 252 | |
| 253 | if (sd) { |
| 254 | close(sd->pipe[0]); |
| 255 | close(sd->pipe[1]); |
| 256 | free(sd); |
| 257 | } |
| 258 | } |
| 259 | |
| 260 | static int fio_spliceio_init(struct thread_data *td) |
| 261 | { |
| 262 | struct spliceio_data *sd = malloc(sizeof(*sd)); |
| 263 | |
| 264 | if (pipe(sd->pipe) < 0) { |
| 265 | td_verror(td, errno, "pipe"); |
| 266 | free(sd); |
| 267 | return 1; |
| 268 | } |
| 269 | |
| 270 | /* |
| 271 | * Assume this work, we'll reset this if it doesn't |
| 272 | */ |
| 273 | sd->vmsplice_to_user = 1; |
| 274 | |
| 275 | /* |
| 276 | * Works with "real" vmsplice to user, eg mapping pages directly. |
| 277 | * Reset if we fail. |
| 278 | */ |
| 279 | sd->vmsplice_to_user_map = 1; |
| 280 | |
| 281 | td->io_ops_data = sd; |
| 282 | return 0; |
| 283 | } |
| 284 | |
| 285 | static struct ioengine_ops ioengine = { |
| 286 | .name = "splice", |
| 287 | .version = FIO_IOOPS_VERSION, |
| 288 | .init = fio_spliceio_init, |
| 289 | .queue = fio_spliceio_queue, |
| 290 | .cleanup = fio_spliceio_cleanup, |
| 291 | .open_file = generic_open_file, |
| 292 | .close_file = generic_close_file, |
| 293 | .get_file_size = generic_get_file_size, |
| 294 | .flags = FIO_SYNCIO | FIO_PIPEIO, |
| 295 | }; |
| 296 | |
| 297 | static void fio_init fio_spliceio_register(void) |
| 298 | { |
| 299 | register_ioengine(&ioengine); |
| 300 | } |
| 301 | |
| 302 | static void fio_exit fio_spliceio_unregister(void) |
| 303 | { |
| 304 | unregister_ioengine(&ioengine); |
| 305 | } |