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 "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 BdrvChild *active_disk; 39 BlockJob *commit_job; 40 BdrvChild *hidden_disk; 41 BdrvChild *secondary_disk; 42 BlockJob *backup_job; 43 char *top_id; 44 ReplicationState *rs; 45 Error *blocker; 46 bool orig_hidden_read_only; 47 bool orig_secondary_read_only; 48 int error; 49 } BDRVReplicationState; 50 51 static void replication_start(ReplicationState *rs, ReplicationMode mode, 52 Error **errp); 53 static void replication_do_checkpoint(ReplicationState *rs, Error **errp); 54 static void replication_get_error(ReplicationState *rs, Error **errp); 55 static void replication_stop(ReplicationState *rs, bool failover, 56 Error **errp); 57 58 #define REPLICATION_MODE "mode" 59 #define REPLICATION_TOP_ID "top-id" 60 static QemuOptsList replication_runtime_opts = { 61 .name = "replication", 62 .head = QTAILQ_HEAD_INITIALIZER(replication_runtime_opts.head), 63 .desc = { 64 { 65 .name = REPLICATION_MODE, 66 .type = QEMU_OPT_STRING, 67 }, 68 { 69 .name = REPLICATION_TOP_ID, 70 .type = QEMU_OPT_STRING, 71 }, 72 { /* end of list */ } 73 }, 74 }; 75 76 static ReplicationOps replication_ops = { 77 .start = replication_start, 78 .checkpoint = replication_do_checkpoint, 79 .get_error = replication_get_error, 80 .stop = replication_stop, 81 }; 82 83 static int replication_open(BlockDriverState *bs, QDict *options, 84 int flags, Error **errp) 85 { 86 int ret; 87 BDRVReplicationState *s = bs->opaque; 88 Error *local_err = NULL; 89 QemuOpts *opts = NULL; 90 const char *mode; 91 const char *top_id; 92 93 bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file, 94 false, errp); 95 if (!bs->file) { 96 return -EINVAL; 97 } 98 99 ret = -EINVAL; 100 opts = qemu_opts_create(&replication_runtime_opts, NULL, 0, &error_abort); 101 qemu_opts_absorb_qdict(opts, options, &local_err); 102 if (local_err) { 103 goto fail; 104 } 105 106 mode = qemu_opt_get(opts, REPLICATION_MODE); 107 if (!mode) { 108 error_setg(&local_err, "Missing the option mode"); 109 goto fail; 110 } 111 112 if (!strcmp(mode, "primary")) { 113 s->mode = REPLICATION_MODE_PRIMARY; 114 top_id = qemu_opt_get(opts, REPLICATION_TOP_ID); 115 if (top_id) { 116 error_setg(&local_err, "The primary side does not support option top-id"); 117 goto fail; 118 } 119 } else if (!strcmp(mode, "secondary")) { 120 s->mode = REPLICATION_MODE_SECONDARY; 121 top_id = qemu_opt_get(opts, REPLICATION_TOP_ID); 122 s->top_id = g_strdup(top_id); 123 if (!s->top_id) { 124 error_setg(&local_err, "Missing the option top-id"); 125 goto fail; 126 } 127 } else { 128 error_setg(&local_err, 129 "The option mode's value should be primary or secondary"); 130 goto fail; 131 } 132 133 s->rs = replication_new(bs, &replication_ops); 134 135 ret = 0; 136 137 fail: 138 qemu_opts_del(opts); 139 error_propagate(errp, local_err); 140 141 return ret; 142 } 143 144 static void replication_close(BlockDriverState *bs) 145 { 146 BDRVReplicationState *s = bs->opaque; 147 148 if (s->stage == BLOCK_REPLICATION_RUNNING) { 149 replication_stop(s->rs, false, NULL); 150 } 151 if (s->stage == BLOCK_REPLICATION_FAILOVER) { 152 job_cancel_sync(&s->commit_job->job); 153 } 154 155 if (s->mode == REPLICATION_MODE_SECONDARY) { 156 g_free(s->top_id); 157 } 158 159 replication_remove(s->rs); 160 } 161 162 static void replication_child_perm(BlockDriverState *bs, BdrvChild *c, 163 const BdrvChildRole *role, 164 BlockReopenQueue *reopen_queue, 165 uint64_t perm, uint64_t shared, 166 uint64_t *nperm, uint64_t *nshared) 167 { 168 *nperm = BLK_PERM_CONSISTENT_READ; 169 if ((bs->open_flags & (BDRV_O_INACTIVE | BDRV_O_RDWR)) == BDRV_O_RDWR) { 170 *nperm |= BLK_PERM_WRITE; 171 } 172 *nshared = BLK_PERM_CONSISTENT_READ \ 173 | BLK_PERM_WRITE \ 174 | BLK_PERM_WRITE_UNCHANGED; 175 return; 176 } 177 178 static int64_t replication_getlength(BlockDriverState *bs) 179 { 180 return bdrv_getlength(bs->file->bs); 181 } 182 183 static int replication_get_io_status(BDRVReplicationState *s) 184 { 185 switch (s->stage) { 186 case BLOCK_REPLICATION_NONE: 187 return -EIO; 188 case BLOCK_REPLICATION_RUNNING: 189 return 0; 190 case BLOCK_REPLICATION_FAILOVER: 191 return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0; 192 case BLOCK_REPLICATION_FAILOVER_FAILED: 193 return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 1; 194 case BLOCK_REPLICATION_DONE: 195 /* 196 * active commit job completes, and active disk and secondary_disk 197 * is swapped, so we can operate bs->file directly 198 */ 199 return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0; 200 default: 201 abort(); 202 } 203 } 204 205 static int replication_return_value(BDRVReplicationState *s, int ret) 206 { 207 if (s->mode == REPLICATION_MODE_SECONDARY) { 208 return ret; 209 } 210 211 if (ret < 0) { 212 s->error = ret; 213 ret = 0; 214 } 215 216 return ret; 217 } 218 219 static coroutine_fn int replication_co_readv(BlockDriverState *bs, 220 int64_t sector_num, 221 int remaining_sectors, 222 QEMUIOVector *qiov) 223 { 224 BDRVReplicationState *s = bs->opaque; 225 int ret; 226 227 if (s->mode == REPLICATION_MODE_PRIMARY) { 228 /* We only use it to forward primary write requests */ 229 return -EIO; 230 } 231 232 ret = replication_get_io_status(s); 233 if (ret < 0) { 234 return ret; 235 } 236 237 ret = bdrv_co_preadv(bs->file, sector_num * BDRV_SECTOR_SIZE, 238 remaining_sectors * BDRV_SECTOR_SIZE, qiov, 0); 239 240 return replication_return_value(s, ret); 241 } 242 243 static coroutine_fn int replication_co_writev(BlockDriverState *bs, 244 int64_t sector_num, 245 int remaining_sectors, 246 QEMUIOVector *qiov, 247 int flags) 248 { 249 BDRVReplicationState *s = bs->opaque; 250 QEMUIOVector hd_qiov; 251 uint64_t bytes_done = 0; 252 BdrvChild *top = bs->file; 253 BdrvChild *base = s->secondary_disk; 254 BdrvChild *target; 255 int ret; 256 int64_t n; 257 258 assert(!flags); 259 ret = replication_get_io_status(s); 260 if (ret < 0) { 261 goto out; 262 } 263 264 if (ret == 0) { 265 ret = bdrv_co_pwritev(top, sector_num * BDRV_SECTOR_SIZE, 266 remaining_sectors * BDRV_SECTOR_SIZE, qiov, 0); 267 return replication_return_value(s, ret); 268 } 269 270 /* 271 * Failover failed, only write to active disk if the sectors 272 * have already been allocated in active disk/hidden disk. 273 */ 274 qemu_iovec_init(&hd_qiov, qiov->niov); 275 while (remaining_sectors > 0) { 276 int64_t count; 277 278 ret = bdrv_is_allocated_above(top->bs, base->bs, false, 279 sector_num * BDRV_SECTOR_SIZE, 280 remaining_sectors * BDRV_SECTOR_SIZE, 281 &count); 282 if (ret < 0) { 283 goto out1; 284 } 285 286 assert(QEMU_IS_ALIGNED(count, BDRV_SECTOR_SIZE)); 287 n = count >> BDRV_SECTOR_BITS; 288 qemu_iovec_reset(&hd_qiov); 289 qemu_iovec_concat(&hd_qiov, qiov, bytes_done, count); 290 291 target = ret ? top : base; 292 ret = bdrv_co_pwritev(target, sector_num * BDRV_SECTOR_SIZE, 293 n * BDRV_SECTOR_SIZE, &hd_qiov, 0); 294 if (ret < 0) { 295 goto out1; 296 } 297 298 remaining_sectors -= n; 299 sector_num += n; 300 bytes_done += count; 301 } 302 303 out1: 304 qemu_iovec_destroy(&hd_qiov); 305 out: 306 return ret; 307 } 308 309 static bool replication_recurse_is_first_non_filter(BlockDriverState *bs, 310 BlockDriverState *candidate) 311 { 312 return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate); 313 } 314 315 static void secondary_do_checkpoint(BDRVReplicationState *s, Error **errp) 316 { 317 Error *local_err = NULL; 318 int ret; 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 if (!s->active_disk->bs->drv) { 332 error_setg(errp, "Active disk %s is ejected", 333 s->active_disk->bs->node_name); 334 return; 335 } 336 337 ret = s->active_disk->bs->drv->bdrv_make_empty(s->active_disk->bs); 338 if (ret < 0) { 339 error_setg(errp, "Cannot make active disk empty"); 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 = s->hidden_disk->bs->drv->bdrv_make_empty(s->hidden_disk->bs); 350 if (ret < 0) { 351 error_setg(errp, "Cannot make hidden disk empty"); 352 return; 353 } 354 } 355 356 /* This function is supposed to be called twice: 357 * first with writable = true, then with writable = false. 358 * The first call puts s->hidden_disk and s->secondary_disk in 359 * r/w mode, and the second puts them back in their original state. 360 */ 361 static void reopen_backing_file(BlockDriverState *bs, bool writable, 362 Error **errp) 363 { 364 BDRVReplicationState *s = bs->opaque; 365 BlockReopenQueue *reopen_queue = NULL; 366 Error *local_err = NULL; 367 368 if (writable) { 369 s->orig_hidden_read_only = bdrv_is_read_only(s->hidden_disk->bs); 370 s->orig_secondary_read_only = bdrv_is_read_only(s->secondary_disk->bs); 371 } 372 373 bdrv_subtree_drained_begin(s->hidden_disk->bs); 374 bdrv_subtree_drained_begin(s->secondary_disk->bs); 375 376 if (s->orig_hidden_read_only) { 377 QDict *opts = qdict_new(); 378 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, !writable); 379 reopen_queue = bdrv_reopen_queue(reopen_queue, s->hidden_disk->bs, 380 opts, true); 381 } 382 383 if (s->orig_secondary_read_only) { 384 QDict *opts = qdict_new(); 385 qdict_put_bool(opts, BDRV_OPT_READ_ONLY, !writable); 386 reopen_queue = bdrv_reopen_queue(reopen_queue, s->secondary_disk->bs, 387 opts, true); 388 } 389 390 if (reopen_queue) { 391 bdrv_reopen_multiple(reopen_queue, &local_err); 392 error_propagate(errp, local_err); 393 } 394 395 bdrv_subtree_drained_end(s->hidden_disk->bs); 396 bdrv_subtree_drained_end(s->secondary_disk->bs); 397 } 398 399 static void backup_job_cleanup(BlockDriverState *bs) 400 { 401 BDRVReplicationState *s = bs->opaque; 402 BlockDriverState *top_bs; 403 404 top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL); 405 if (!top_bs) { 406 return; 407 } 408 bdrv_op_unblock_all(top_bs, s->blocker); 409 error_free(s->blocker); 410 reopen_backing_file(bs, false, NULL); 411 } 412 413 static void backup_job_completed(void *opaque, int ret) 414 { 415 BlockDriverState *bs = opaque; 416 BDRVReplicationState *s = bs->opaque; 417 418 if (s->stage != BLOCK_REPLICATION_FAILOVER) { 419 /* The backup job is cancelled unexpectedly */ 420 s->error = -EIO; 421 } 422 423 backup_job_cleanup(bs); 424 } 425 426 static bool check_top_bs(BlockDriverState *top_bs, BlockDriverState *bs) 427 { 428 BdrvChild *child; 429 430 /* The bs itself is the top_bs */ 431 if (top_bs == bs) { 432 return true; 433 } 434 435 /* Iterate over top_bs's children */ 436 QLIST_FOREACH(child, &top_bs->children, next) { 437 if (child->bs == bs || check_top_bs(child->bs, bs)) { 438 return true; 439 } 440 } 441 442 return false; 443 } 444 445 static void replication_start(ReplicationState *rs, ReplicationMode mode, 446 Error **errp) 447 { 448 BlockDriverState *bs = rs->opaque; 449 BDRVReplicationState *s; 450 BlockDriverState *top_bs; 451 int64_t active_length, hidden_length, disk_length; 452 AioContext *aio_context; 453 Error *local_err = NULL; 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 /* Must be true, or the bdrv_getlength() calls would have failed */ 511 assert(s->active_disk->bs->drv && s->hidden_disk->bs->drv); 512 513 if (!s->active_disk->bs->drv->bdrv_make_empty || 514 !s->hidden_disk->bs->drv->bdrv_make_empty) { 515 error_setg(errp, 516 "Active disk or hidden disk doesn't support make_empty"); 517 aio_context_release(aio_context); 518 return; 519 } 520 521 /* reopen the backing file in r/w mode */ 522 reopen_backing_file(bs, true, &local_err); 523 if (local_err) { 524 error_propagate(errp, local_err); 525 aio_context_release(aio_context); 526 return; 527 } 528 529 /* start backup job now */ 530 error_setg(&s->blocker, 531 "Block device is in use by internal backup job"); 532 533 top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL); 534 if (!top_bs || !bdrv_is_root_node(top_bs) || 535 !check_top_bs(top_bs, bs)) { 536 error_setg(errp, "No top_bs or it is invalid"); 537 reopen_backing_file(bs, false, NULL); 538 aio_context_release(aio_context); 539 return; 540 } 541 bdrv_op_block_all(top_bs, s->blocker); 542 bdrv_op_unblock(top_bs, BLOCK_OP_TYPE_DATAPLANE, s->blocker); 543 544 s->backup_job = backup_job_create( 545 NULL, s->secondary_disk->bs, s->hidden_disk->bs, 546 0, MIRROR_SYNC_MODE_NONE, NULL, 0, false, NULL, 547 BLOCKDEV_ON_ERROR_REPORT, 548 BLOCKDEV_ON_ERROR_REPORT, JOB_INTERNAL, 549 backup_job_completed, bs, NULL, &local_err); 550 if (local_err) { 551 error_propagate(errp, local_err); 552 backup_job_cleanup(bs); 553 aio_context_release(aio_context); 554 return; 555 } 556 job_start(&s->backup_job->job); 557 break; 558 default: 559 aio_context_release(aio_context); 560 abort(); 561 } 562 563 s->stage = BLOCK_REPLICATION_RUNNING; 564 565 if (s->mode == REPLICATION_MODE_SECONDARY) { 566 secondary_do_checkpoint(s, errp); 567 } 568 569 s->error = 0; 570 aio_context_release(aio_context); 571 } 572 573 static void replication_do_checkpoint(ReplicationState *rs, Error **errp) 574 { 575 BlockDriverState *bs = rs->opaque; 576 BDRVReplicationState *s; 577 AioContext *aio_context; 578 579 aio_context = bdrv_get_aio_context(bs); 580 aio_context_acquire(aio_context); 581 s = bs->opaque; 582 583 if (s->mode == REPLICATION_MODE_SECONDARY) { 584 secondary_do_checkpoint(s, errp); 585 } 586 aio_context_release(aio_context); 587 } 588 589 static void replication_get_error(ReplicationState *rs, Error **errp) 590 { 591 BlockDriverState *bs = rs->opaque; 592 BDRVReplicationState *s; 593 AioContext *aio_context; 594 595 aio_context = bdrv_get_aio_context(bs); 596 aio_context_acquire(aio_context); 597 s = bs->opaque; 598 599 if (s->stage != BLOCK_REPLICATION_RUNNING) { 600 error_setg(errp, "Block replication is not running"); 601 aio_context_release(aio_context); 602 return; 603 } 604 605 if (s->error) { 606 error_setg(errp, "I/O error occurred"); 607 aio_context_release(aio_context); 608 return; 609 } 610 aio_context_release(aio_context); 611 } 612 613 static void replication_done(void *opaque, int ret) 614 { 615 BlockDriverState *bs = opaque; 616 BDRVReplicationState *s = bs->opaque; 617 618 if (ret == 0) { 619 s->stage = BLOCK_REPLICATION_DONE; 620 621 s->active_disk = NULL; 622 s->secondary_disk = NULL; 623 s->hidden_disk = NULL; 624 s->error = 0; 625 } else { 626 s->stage = BLOCK_REPLICATION_FAILOVER_FAILED; 627 s->error = -EIO; 628 } 629 } 630 631 static void replication_stop(ReplicationState *rs, bool failover, Error **errp) 632 { 633 BlockDriverState *bs = rs->opaque; 634 BDRVReplicationState *s; 635 AioContext *aio_context; 636 637 aio_context = bdrv_get_aio_context(bs); 638 aio_context_acquire(aio_context); 639 s = bs->opaque; 640 641 if (s->stage != BLOCK_REPLICATION_RUNNING) { 642 error_setg(errp, "Block replication is not running"); 643 aio_context_release(aio_context); 644 return; 645 } 646 647 switch (s->mode) { 648 case REPLICATION_MODE_PRIMARY: 649 s->stage = BLOCK_REPLICATION_DONE; 650 s->error = 0; 651 break; 652 case REPLICATION_MODE_SECONDARY: 653 /* 654 * This BDS will be closed, and the job should be completed 655 * before the BDS is closed, because we will access hidden 656 * disk, secondary disk in backup_job_completed(). 657 */ 658 if (s->backup_job) { 659 job_cancel_sync(&s->backup_job->job); 660 } 661 662 if (!failover) { 663 secondary_do_checkpoint(s, errp); 664 s->stage = BLOCK_REPLICATION_DONE; 665 aio_context_release(aio_context); 666 return; 667 } 668 669 s->stage = BLOCK_REPLICATION_FAILOVER; 670 s->commit_job = commit_active_start( 671 NULL, s->active_disk->bs, s->secondary_disk->bs, 672 JOB_INTERNAL, 0, BLOCKDEV_ON_ERROR_REPORT, 673 NULL, replication_done, bs, true, errp); 674 break; 675 default: 676 aio_context_release(aio_context); 677 abort(); 678 } 679 aio_context_release(aio_context); 680 } 681 682 static const char *const replication_strong_runtime_opts[] = { 683 REPLICATION_MODE, 684 REPLICATION_TOP_ID, 685 686 NULL 687 }; 688 689 static BlockDriver bdrv_replication = { 690 .format_name = "replication", 691 .instance_size = sizeof(BDRVReplicationState), 692 693 .bdrv_open = replication_open, 694 .bdrv_close = replication_close, 695 .bdrv_child_perm = replication_child_perm, 696 697 .bdrv_getlength = replication_getlength, 698 .bdrv_co_readv = replication_co_readv, 699 .bdrv_co_writev = replication_co_writev, 700 701 .is_filter = true, 702 .bdrv_recurse_is_first_non_filter = replication_recurse_is_first_non_filter, 703 704 .has_variable_length = true, 705 .strong_runtime_opts = replication_strong_runtime_opts, 706 }; 707 708 static void bdrv_replication_init(void) 709 { 710 bdrv_register(&bdrv_replication); 711 } 712 713 block_init(bdrv_replication_init); 714