1 /* 2 * Replication Block filter 3 * 4 * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD. 5 * Copyright (c) 2016 Intel Corporation 6 * Copyright (c) 2016 FUJITSU LIMITED 7 * 8 * Author: 9 * Wen Congyang <wency@cn.fujitsu.com> 10 * 11 * This work is licensed under the terms of the GNU GPL, version 2 or later. 12 * See the COPYING file in the top-level directory. 13 */ 14 15 #include "qemu/osdep.h" 16 #include "qemu/module.h" 17 #include "qemu/option.h" 18 #include "block/nbd.h" 19 #include "block/blockjob.h" 20 #include "block/block_int.h" 21 #include "block/block_backup.h" 22 #include "sysemu/block-backend.h" 23 #include "qapi/error.h" 24 #include "qapi/qmp/qdict.h" 25 #include "block/replication.h" 26 27 typedef enum { 28 BLOCK_REPLICATION_NONE, /* block replication is not started */ 29 BLOCK_REPLICATION_RUNNING, /* block replication is running */ 30 BLOCK_REPLICATION_FAILOVER, /* failover is running in background */ 31 BLOCK_REPLICATION_FAILOVER_FAILED, /* failover failed */ 32 BLOCK_REPLICATION_DONE, /* block replication is done */ 33 } ReplicationStage; 34 35 typedef struct BDRVReplicationState { 36 ReplicationMode mode; 37 ReplicationStage stage; 38 BlockJob *commit_job; 39 BdrvChild *hidden_disk; 40 BdrvChild *secondary_disk; 41 BlockJob *backup_job; 42 char *top_id; 43 ReplicationState *rs; 44 Error *blocker; 45 bool orig_hidden_read_only; 46 bool orig_secondary_read_only; 47 int error; 48 } BDRVReplicationState; 49 50 static void replication_start(ReplicationState *rs, ReplicationMode mode, 51 Error **errp); 52 static void replication_do_checkpoint(ReplicationState *rs, Error **errp); 53 static void replication_get_error(ReplicationState *rs, Error **errp); 54 static void replication_stop(ReplicationState *rs, bool failover, 55 Error **errp); 56 57 #define REPLICATION_MODE "mode" 58 #define REPLICATION_TOP_ID "top-id" 59 static QemuOptsList replication_runtime_opts = { 60 .name = "replication", 61 .head = QTAILQ_HEAD_INITIALIZER(replication_runtime_opts.head), 62 .desc = { 63 { 64 .name = REPLICATION_MODE, 65 .type = QEMU_OPT_STRING, 66 }, 67 { 68 .name = REPLICATION_TOP_ID, 69 .type = QEMU_OPT_STRING, 70 }, 71 { /* end of list */ } 72 }, 73 }; 74 75 static ReplicationOps replication_ops = { 76 .start = replication_start, 77 .checkpoint = replication_do_checkpoint, 78 .get_error = replication_get_error, 79 .stop = replication_stop, 80 }; 81 82 static int replication_open(BlockDriverState *bs, QDict *options, 83 int flags, Error **errp) 84 { 85 int ret; 86 BDRVReplicationState *s = bs->opaque; 87 QemuOpts *opts = NULL; 88 const char *mode; 89 const char *top_id; 90 91 ret = bdrv_open_file_child(NULL, options, "file", bs, errp); 92 if (ret < 0) { 93 return ret; 94 } 95 96 ret = -EINVAL; 97 opts = qemu_opts_create(&replication_runtime_opts, NULL, 0, &error_abort); 98 if (!qemu_opts_absorb_qdict(opts, options, errp)) { 99 goto fail; 100 } 101 102 mode = qemu_opt_get(opts, REPLICATION_MODE); 103 if (!mode) { 104 error_setg(errp, "Missing the option mode"); 105 goto fail; 106 } 107 108 if (!strcmp(mode, "primary")) { 109 s->mode = REPLICATION_MODE_PRIMARY; 110 top_id = qemu_opt_get(opts, REPLICATION_TOP_ID); 111 if (top_id) { 112 error_setg(errp, 113 "The primary side does not support option top-id"); 114 goto fail; 115 } 116 } else if (!strcmp(mode, "secondary")) { 117 s->mode = REPLICATION_MODE_SECONDARY; 118 top_id = qemu_opt_get(opts, REPLICATION_TOP_ID); 119 s->top_id = g_strdup(top_id); 120 if (!s->top_id) { 121 error_setg(errp, "Missing the option top-id"); 122 goto fail; 123 } 124 } else { 125 error_setg(errp, 126 "The option mode's value should be primary or secondary"); 127 goto fail; 128 } 129 130 s->rs = replication_new(bs, &replication_ops); 131 132 ret = 0; 133 134 fail: 135 qemu_opts_del(opts); 136 return ret; 137 } 138 139 static void replication_close(BlockDriverState *bs) 140 { 141 BDRVReplicationState *s = bs->opaque; 142 Job *commit_job; 143 GLOBAL_STATE_CODE(); 144 145 if (s->stage == BLOCK_REPLICATION_RUNNING) { 146 replication_stop(s->rs, false, NULL); 147 } 148 if (s->stage == BLOCK_REPLICATION_FAILOVER) { 149 commit_job = &s->commit_job->job; 150 assert(commit_job->aio_context == qemu_get_current_aio_context()); 151 job_cancel_sync(commit_job, false); 152 } 153 154 if (s->mode == REPLICATION_MODE_SECONDARY) { 155 g_free(s->top_id); 156 } 157 158 replication_remove(s->rs); 159 } 160 161 static void replication_child_perm(BlockDriverState *bs, BdrvChild *c, 162 BdrvChildRole role, 163 BlockReopenQueue *reopen_queue, 164 uint64_t perm, uint64_t shared, 165 uint64_t *nperm, uint64_t *nshared) 166 { 167 if (role & BDRV_CHILD_PRIMARY) { 168 *nperm = BLK_PERM_CONSISTENT_READ; 169 } else { 170 *nperm = 0; 171 } 172 173 if ((bs->open_flags & (BDRV_O_INACTIVE | BDRV_O_RDWR)) == BDRV_O_RDWR) { 174 *nperm |= BLK_PERM_WRITE; 175 } 176 *nshared = BLK_PERM_CONSISTENT_READ 177 | BLK_PERM_WRITE 178 | BLK_PERM_WRITE_UNCHANGED; 179 return; 180 } 181 182 static int64_t coroutine_fn GRAPH_RDLOCK 183 replication_co_getlength(BlockDriverState *bs) 184 { 185 return bdrv_co_getlength(bs->file->bs); 186 } 187 188 static int replication_get_io_status(BDRVReplicationState *s) 189 { 190 switch (s->stage) { 191 case BLOCK_REPLICATION_NONE: 192 return -EIO; 193 case BLOCK_REPLICATION_RUNNING: 194 return 0; 195 case BLOCK_REPLICATION_FAILOVER: 196 return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0; 197 case BLOCK_REPLICATION_FAILOVER_FAILED: 198 return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 1; 199 case BLOCK_REPLICATION_DONE: 200 /* 201 * active commit job completes, and active disk and secondary_disk 202 * is swapped, so we can operate bs->file directly 203 */ 204 return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0; 205 default: 206 abort(); 207 } 208 } 209 210 static int replication_return_value(BDRVReplicationState *s, int ret) 211 { 212 if (s->mode == REPLICATION_MODE_SECONDARY) { 213 return ret; 214 } 215 216 if (ret < 0) { 217 s->error = ret; 218 ret = 0; 219 } 220 221 return ret; 222 } 223 224 static int coroutine_fn GRAPH_RDLOCK 225 replication_co_readv(BlockDriverState *bs, int64_t sector_num, 226 int remaining_sectors, QEMUIOVector *qiov) 227 { 228 BDRVReplicationState *s = bs->opaque; 229 int ret; 230 231 if (s->mode == REPLICATION_MODE_PRIMARY) { 232 /* We only use it to forward primary write requests */ 233 return -EIO; 234 } 235 236 ret = replication_get_io_status(s); 237 if (ret < 0) { 238 return ret; 239 } 240 241 ret = bdrv_co_preadv(bs->file, sector_num * BDRV_SECTOR_SIZE, 242 remaining_sectors * BDRV_SECTOR_SIZE, qiov, 0); 243 244 return replication_return_value(s, ret); 245 } 246 247 static int coroutine_fn GRAPH_RDLOCK 248 replication_co_writev(BlockDriverState *bs, int64_t sector_num, 249 int remaining_sectors, QEMUIOVector *qiov, int flags) 250 { 251 BDRVReplicationState *s = bs->opaque; 252 QEMUIOVector hd_qiov; 253 uint64_t bytes_done = 0; 254 BdrvChild *top = bs->file; 255 BdrvChild *base = s->secondary_disk; 256 BdrvChild *target; 257 int ret; 258 int64_t n; 259 260 ret = replication_get_io_status(s); 261 if (ret < 0) { 262 goto out; 263 } 264 265 if (ret == 0) { 266 ret = bdrv_co_pwritev(top, sector_num * BDRV_SECTOR_SIZE, 267 remaining_sectors * BDRV_SECTOR_SIZE, qiov, 0); 268 return replication_return_value(s, ret); 269 } 270 271 /* 272 * Failover failed, only write to active disk if the sectors 273 * have already been allocated in active disk/hidden disk. 274 */ 275 qemu_iovec_init(&hd_qiov, qiov->niov); 276 while (remaining_sectors > 0) { 277 int64_t count; 278 279 ret = bdrv_co_is_allocated_above(top->bs, base->bs, false, 280 sector_num * BDRV_SECTOR_SIZE, 281 remaining_sectors * BDRV_SECTOR_SIZE, 282 &count); 283 if (ret < 0) { 284 goto out1; 285 } 286 287 assert(QEMU_IS_ALIGNED(count, BDRV_SECTOR_SIZE)); 288 n = count >> BDRV_SECTOR_BITS; 289 qemu_iovec_reset(&hd_qiov); 290 qemu_iovec_concat(&hd_qiov, qiov, bytes_done, count); 291 292 target = ret ? top : base; 293 ret = bdrv_co_pwritev(target, sector_num * BDRV_SECTOR_SIZE, 294 n * BDRV_SECTOR_SIZE, &hd_qiov, 0); 295 if (ret < 0) { 296 goto out1; 297 } 298 299 remaining_sectors -= n; 300 sector_num += n; 301 bytes_done += count; 302 } 303 304 out1: 305 qemu_iovec_destroy(&hd_qiov); 306 out: 307 return ret; 308 } 309 310 static void GRAPH_UNLOCKED 311 secondary_do_checkpoint(BlockDriverState *bs, Error **errp) 312 { 313 BDRVReplicationState *s = bs->opaque; 314 BdrvChild *active_disk; 315 Error *local_err = NULL; 316 int ret; 317 318 GRAPH_RDLOCK_GUARD_MAINLOOP(); 319 320 if (!s->backup_job) { 321 error_setg(errp, "Backup job was cancelled unexpectedly"); 322 return; 323 } 324 325 backup_do_checkpoint(s->backup_job, &local_err); 326 if (local_err) { 327 error_propagate(errp, local_err); 328 return; 329 } 330 331 active_disk = bs->file; 332 if (!active_disk->bs->drv) { 333 error_setg(errp, "Active disk %s is ejected", 334 active_disk->bs->node_name); 335 return; 336 } 337 338 ret = bdrv_make_empty(active_disk, errp); 339 if (ret < 0) { 340 return; 341 } 342 343 if (!s->hidden_disk->bs->drv) { 344 error_setg(errp, "Hidden disk %s is ejected", 345 s->hidden_disk->bs->node_name); 346 return; 347 } 348 349 ret = bdrv_make_empty(s->hidden_disk, errp); 350 if (ret < 0) { 351 return; 352 } 353 } 354 355 /* This function is supposed to be called twice: 356 * first with writable = true, then with writable = false. 357 * The first call puts s->hidden_disk and s->secondary_disk in 358 * r/w mode, and the second puts them back in their original state. 359 */ 360 static void reopen_backing_file(BlockDriverState *bs, bool writable, 361 Error **errp) 362 { 363 BDRVReplicationState *s = bs->opaque; 364 BdrvChild *hidden_disk, *secondary_disk; 365 BlockReopenQueue *reopen_queue = NULL; 366 367 GLOBAL_STATE_CODE(); 368 GRAPH_RDLOCK_GUARD_MAINLOOP(); 369 370 /* 371 * s->hidden_disk and s->secondary_disk may not be set yet, as they will 372 * only be set after the children are writable. 373 */ 374 hidden_disk = bs->file->bs->backing; 375 secondary_disk = hidden_disk->bs->backing; 376 377 if (writable) { 378 s->orig_hidden_read_only = bdrv_is_read_only(hidden_disk->bs); 379 s->orig_secondary_read_only = bdrv_is_read_only(secondary_disk->bs); 380 } 381 382 if (s->orig_hidden_read_only) { 383 QDict *opts = qdict_new(); 384 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, !writable); 385 reopen_queue = bdrv_reopen_queue(reopen_queue, hidden_disk->bs, 386 opts, true); 387 } 388 389 if (s->orig_secondary_read_only) { 390 QDict *opts = qdict_new(); 391 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, !writable); 392 reopen_queue = bdrv_reopen_queue(reopen_queue, secondary_disk->bs, 393 opts, true); 394 } 395 396 if (reopen_queue) { 397 bdrv_reopen_multiple(reopen_queue, errp); 398 } 399 } 400 401 static void backup_job_cleanup(BlockDriverState *bs) 402 { 403 BDRVReplicationState *s = bs->opaque; 404 BlockDriverState *top_bs; 405 406 s->backup_job = NULL; 407 408 top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL); 409 if (!top_bs) { 410 return; 411 } 412 bdrv_op_unblock_all(top_bs, s->blocker); 413 error_free(s->blocker); 414 reopen_backing_file(bs, false, NULL); 415 } 416 417 static void backup_job_completed(void *opaque, int ret) 418 { 419 BlockDriverState *bs = opaque; 420 BDRVReplicationState *s = bs->opaque; 421 422 if (s->stage != BLOCK_REPLICATION_FAILOVER) { 423 /* The backup job is cancelled unexpectedly */ 424 s->error = -EIO; 425 } 426 427 backup_job_cleanup(bs); 428 } 429 430 static bool GRAPH_RDLOCK 431 check_top_bs(BlockDriverState *top_bs, BlockDriverState *bs) 432 { 433 BdrvChild *child; 434 435 /* The bs itself is the top_bs */ 436 if (top_bs == bs) { 437 return true; 438 } 439 440 /* Iterate over top_bs's children */ 441 QLIST_FOREACH(child, &top_bs->children, next) { 442 if (child->bs == bs || check_top_bs(child->bs, bs)) { 443 return true; 444 } 445 } 446 447 return false; 448 } 449 450 static void replication_start(ReplicationState *rs, ReplicationMode mode, 451 Error **errp) 452 { 453 BlockDriverState *bs = rs->opaque; 454 BDRVReplicationState *s; 455 BlockDriverState *top_bs; 456 BdrvChild *active_disk, *hidden_disk, *secondary_disk; 457 int64_t active_length, hidden_length, disk_length; 458 Error *local_err = NULL; 459 BackupPerf perf = { .use_copy_range = true, .max_workers = 1 }; 460 461 GLOBAL_STATE_CODE(); 462 463 s = bs->opaque; 464 465 if (s->stage == BLOCK_REPLICATION_DONE || 466 s->stage == BLOCK_REPLICATION_FAILOVER) { 467 /* 468 * This case happens when a secondary is promoted to primary. 469 * Ignore the request because the secondary side of replication 470 * doesn't have to do anything anymore. 471 */ 472 return; 473 } 474 475 if (s->stage != BLOCK_REPLICATION_NONE) { 476 error_setg(errp, "Block replication is running or done"); 477 return; 478 } 479 480 if (s->mode != mode) { 481 error_setg(errp, "The parameter mode's value is invalid, needs %d," 482 " but got %d", s->mode, mode); 483 return; 484 } 485 486 switch (s->mode) { 487 case REPLICATION_MODE_PRIMARY: 488 break; 489 case REPLICATION_MODE_SECONDARY: 490 bdrv_graph_rdlock_main_loop(); 491 active_disk = bs->file; 492 if (!active_disk || !active_disk->bs || !active_disk->bs->backing) { 493 error_setg(errp, "Active disk doesn't have backing file"); 494 bdrv_graph_rdunlock_main_loop(); 495 return; 496 } 497 498 hidden_disk = active_disk->bs->backing; 499 if (!hidden_disk->bs || !hidden_disk->bs->backing) { 500 error_setg(errp, "Hidden disk doesn't have backing file"); 501 bdrv_graph_rdunlock_main_loop(); 502 return; 503 } 504 505 secondary_disk = hidden_disk->bs->backing; 506 if (!secondary_disk->bs || !bdrv_has_blk(secondary_disk->bs)) { 507 error_setg(errp, "The secondary disk doesn't have block backend"); 508 bdrv_graph_rdunlock_main_loop(); 509 return; 510 } 511 bdrv_graph_rdunlock_main_loop(); 512 513 /* verify the length */ 514 active_length = bdrv_getlength(active_disk->bs); 515 hidden_length = bdrv_getlength(hidden_disk->bs); 516 disk_length = bdrv_getlength(secondary_disk->bs); 517 if (active_length < 0 || hidden_length < 0 || disk_length < 0 || 518 active_length != hidden_length || hidden_length != disk_length) { 519 error_setg(errp, "Active disk, hidden disk, secondary disk's length" 520 " are not the same"); 521 return; 522 } 523 524 /* Must be true, or the bdrv_getlength() calls would have failed */ 525 assert(active_disk->bs->drv && hidden_disk->bs->drv); 526 527 bdrv_graph_rdlock_main_loop(); 528 if (!active_disk->bs->drv->bdrv_make_empty || 529 !hidden_disk->bs->drv->bdrv_make_empty) { 530 error_setg(errp, 531 "Active disk or hidden disk doesn't support make_empty"); 532 bdrv_graph_rdunlock_main_loop(); 533 return; 534 } 535 bdrv_graph_rdunlock_main_loop(); 536 537 /* reopen the backing file in r/w mode */ 538 reopen_backing_file(bs, true, &local_err); 539 if (local_err) { 540 error_propagate(errp, local_err); 541 return; 542 } 543 544 bdrv_graph_wrlock(); 545 546 bdrv_ref(hidden_disk->bs); 547 s->hidden_disk = bdrv_attach_child(bs, hidden_disk->bs, "hidden disk", 548 &child_of_bds, BDRV_CHILD_DATA, 549 &local_err); 550 if (local_err) { 551 error_propagate(errp, local_err); 552 bdrv_graph_wrunlock(); 553 return; 554 } 555 556 bdrv_ref(secondary_disk->bs); 557 s->secondary_disk = bdrv_attach_child(bs, secondary_disk->bs, 558 "secondary disk", &child_of_bds, 559 BDRV_CHILD_DATA, &local_err); 560 if (local_err) { 561 error_propagate(errp, local_err); 562 bdrv_graph_wrunlock(); 563 return; 564 } 565 566 /* start backup job now */ 567 error_setg(&s->blocker, 568 "Block device is in use by internal backup job"); 569 570 top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL); 571 if (!top_bs || !bdrv_is_root_node(top_bs) || 572 !check_top_bs(top_bs, bs)) { 573 error_setg(errp, "No top_bs or it is invalid"); 574 bdrv_graph_wrunlock(); 575 reopen_backing_file(bs, false, NULL); 576 return; 577 } 578 bdrv_op_block_all(top_bs, s->blocker); 579 bdrv_op_unblock(top_bs, BLOCK_OP_TYPE_DATAPLANE, s->blocker); 580 581 bdrv_graph_wrunlock(); 582 583 s->backup_job = backup_job_create( 584 NULL, s->secondary_disk->bs, s->hidden_disk->bs, 585 0, MIRROR_SYNC_MODE_NONE, NULL, 0, false, false, 586 NULL, &perf, 587 BLOCKDEV_ON_ERROR_REPORT, 588 BLOCKDEV_ON_ERROR_REPORT, JOB_INTERNAL, 589 backup_job_completed, bs, NULL, &local_err); 590 if (local_err) { 591 error_propagate(errp, local_err); 592 backup_job_cleanup(bs); 593 return; 594 } 595 job_start(&s->backup_job->job); 596 break; 597 default: 598 abort(); 599 } 600 601 s->stage = BLOCK_REPLICATION_RUNNING; 602 603 if (s->mode == REPLICATION_MODE_SECONDARY) { 604 secondary_do_checkpoint(bs, errp); 605 } 606 607 s->error = 0; 608 } 609 610 static void replication_do_checkpoint(ReplicationState *rs, Error **errp) 611 { 612 BlockDriverState *bs = rs->opaque; 613 BDRVReplicationState *s = bs->opaque; 614 615 if (s->stage == BLOCK_REPLICATION_DONE || 616 s->stage == BLOCK_REPLICATION_FAILOVER) { 617 /* 618 * This case happens when a secondary was promoted to primary. 619 * Ignore the request because the secondary side of replication 620 * doesn't have to do anything anymore. 621 */ 622 return; 623 } 624 625 if (s->mode == REPLICATION_MODE_SECONDARY) { 626 secondary_do_checkpoint(bs, errp); 627 } 628 } 629 630 static void replication_get_error(ReplicationState *rs, Error **errp) 631 { 632 BlockDriverState *bs = rs->opaque; 633 BDRVReplicationState *s = bs->opaque; 634 635 if (s->stage == BLOCK_REPLICATION_NONE) { 636 error_setg(errp, "Block replication is not running"); 637 return; 638 } 639 640 if (s->error) { 641 error_setg(errp, "I/O error occurred"); 642 return; 643 } 644 } 645 646 static void replication_done(void *opaque, int ret) 647 { 648 BlockDriverState *bs = opaque; 649 BDRVReplicationState *s = bs->opaque; 650 651 if (ret == 0) { 652 s->stage = BLOCK_REPLICATION_DONE; 653 654 bdrv_graph_wrlock(); 655 bdrv_unref_child(bs, s->secondary_disk); 656 s->secondary_disk = NULL; 657 bdrv_unref_child(bs, s->hidden_disk); 658 s->hidden_disk = NULL; 659 bdrv_graph_wrunlock(); 660 661 s->error = 0; 662 } else { 663 s->stage = BLOCK_REPLICATION_FAILOVER_FAILED; 664 s->error = -EIO; 665 } 666 } 667 668 static void replication_stop(ReplicationState *rs, bool failover, Error **errp) 669 { 670 BlockDriverState *bs = rs->opaque; 671 BDRVReplicationState *s = bs->opaque; 672 673 if (s->stage == BLOCK_REPLICATION_DONE || 674 s->stage == BLOCK_REPLICATION_FAILOVER) { 675 /* 676 * This case happens when a secondary was promoted to primary. 677 * Ignore the request because the secondary side of replication 678 * doesn't have to do anything anymore. 679 */ 680 return; 681 } 682 683 if (s->stage != BLOCK_REPLICATION_RUNNING) { 684 error_setg(errp, "Block replication is not running"); 685 return; 686 } 687 688 switch (s->mode) { 689 case REPLICATION_MODE_PRIMARY: 690 s->stage = BLOCK_REPLICATION_DONE; 691 s->error = 0; 692 break; 693 case REPLICATION_MODE_SECONDARY: 694 /* 695 * This BDS will be closed, and the job should be completed 696 * before the BDS is closed, because we will access hidden 697 * disk, secondary disk in backup_job_completed(). 698 */ 699 if (s->backup_job) { 700 job_cancel_sync(&s->backup_job->job, true); 701 } 702 703 if (!failover) { 704 secondary_do_checkpoint(bs, errp); 705 s->stage = BLOCK_REPLICATION_DONE; 706 return; 707 } 708 709 bdrv_graph_rdlock_main_loop(); 710 s->stage = BLOCK_REPLICATION_FAILOVER; 711 s->commit_job = commit_active_start( 712 NULL, bs->file->bs, s->secondary_disk->bs, 713 JOB_INTERNAL, 0, BLOCKDEV_ON_ERROR_REPORT, 714 NULL, replication_done, bs, true, errp); 715 bdrv_graph_rdunlock_main_loop(); 716 break; 717 default: 718 abort(); 719 } 720 } 721 722 static const char *const replication_strong_runtime_opts[] = { 723 REPLICATION_MODE, 724 REPLICATION_TOP_ID, 725 726 NULL 727 }; 728 729 static BlockDriver bdrv_replication = { 730 .format_name = "replication", 731 .instance_size = sizeof(BDRVReplicationState), 732 733 .bdrv_open = replication_open, 734 .bdrv_close = replication_close, 735 .bdrv_child_perm = replication_child_perm, 736 737 .bdrv_co_getlength = replication_co_getlength, 738 .bdrv_co_readv = replication_co_readv, 739 .bdrv_co_writev = replication_co_writev, 740 741 .is_filter = true, 742 743 .strong_runtime_opts = replication_strong_runtime_opts, 744 }; 745 746 static void bdrv_replication_init(void) 747 { 748 bdrv_register(&bdrv_replication); 749 } 750 751 block_init(bdrv_replication_init); 752