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