block/replication.c

   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     Job *commit_job;
 148
 149     if (s->stage == BLOCK_REPLICATION_RUNNING) {
 150         replication_stop(s->rs, false, NULL);
 151     }
 152     if (s->stage == BLOCK_REPLICATION_FAILOVER) {
 153         commit_job = &s->commit_job->job;
 154         assert(commit_job->aio_context == qemu_get_current_aio_context());
 155         job_cancel_sync(commit_job);
 156     }
 157
 158     if (s->mode == REPLICATION_MODE_SECONDARY) {
 159         g_free(s->top_id);
 160     }
 161
 162     replication_remove(s->rs);
 163 }
 164
 165 static void replication_child_perm(BlockDriverState *bs, BdrvChild *c,
 166                                    const BdrvChildRole *role,
 167                                    BlockReopenQueue *reopen_queue,
 168                                    uint64_t perm, uint64_t shared,
 169                                    uint64_t *nperm, uint64_t *nshared)
 170 {
 171     *nperm = BLK_PERM_CONSISTENT_READ;
 172     if ((bs->open_flags & (BDRV_O_INACTIVE | BDRV_O_RDWR)) == BDRV_O_RDWR) {
 173         *nperm |= BLK_PERM_WRITE;
 174     }
 175     *nshared = BLK_PERM_CONSISTENT_READ
 176                | BLK_PERM_WRITE
 177                | BLK_PERM_WRITE_UNCHANGED;
 178     return;
 179 }
 180
 181 static int64_t replication_getlength(BlockDriverState *bs)
 182 {
 183     return bdrv_getlength(bs->file->bs);
 184 }
 185
 186 static int replication_get_io_status(BDRVReplicationState *s)
 187 {
 188     switch (s->stage) {
 189     case BLOCK_REPLICATION_NONE:
 190         return -EIO;
 191     case BLOCK_REPLICATION_RUNNING:
 192         return 0;
 193     case BLOCK_REPLICATION_FAILOVER:
 194         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
 195     case BLOCK_REPLICATION_FAILOVER_FAILED:
 196         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 1;
 197     case BLOCK_REPLICATION_DONE:
 198         /*
 199          * active commit job completes, and active disk and secondary_disk
 200          * is swapped, so we can operate bs->file directly
 201          */
 202         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
 203     default:
 204         abort();
 205     }
 206 }
 207
 208 static int replication_return_value(BDRVReplicationState *s, int ret)
 209 {
 210     if (s->mode == REPLICATION_MODE_SECONDARY) {
 211         return ret;
 212     }
 213
 214     if (ret < 0) {
 215         s->error = ret;
 216         ret = 0;
 217     }
 218
 219     return ret;
 220 }
 221
 222 static coroutine_fn int replication_co_readv(BlockDriverState *bs,
 223                                              int64_t sector_num,
 224                                              int remaining_sectors,
 225                                              QEMUIOVector *qiov)
 226 {
 227     BDRVReplicationState *s = bs->opaque;
 228     int ret;
 229
 230     if (s->mode == REPLICATION_MODE_PRIMARY) {
 231         /* We only use it to forward primary write requests */
 232         return -EIO;
 233     }
 234
 235     ret = replication_get_io_status(s);
 236     if (ret < 0) {
 237         return ret;
 238     }
 239
 240     ret = bdrv_co_preadv(bs->file, sector_num * BDRV_SECTOR_SIZE,
 241                          remaining_sectors * BDRV_SECTOR_SIZE, qiov, 0);
 242
 243     return replication_return_value(s, ret);
 244 }
 245
 246 static coroutine_fn int replication_co_writev(BlockDriverState *bs,
 247                                               int64_t sector_num,
 248                                               int remaining_sectors,
 249                                               QEMUIOVector *qiov,
 250                                               int flags)
 251 {
 252     BDRVReplicationState *s = bs->opaque;
 253     QEMUIOVector hd_qiov;
 254     uint64_t bytes_done = 0;
 255     BdrvChild *top = bs->file;
 256     BdrvChild *base = s->secondary_disk;
 257     BdrvChild *target;
 258     int ret;
 259     int64_t n;
 260
 261     assert(!flags);
 262     ret = replication_get_io_status(s);
 263     if (ret < 0) {
 264         goto out;
 265     }
 266
 267     if (ret == 0) {
 268         ret = bdrv_co_pwritev(top, sector_num * BDRV_SECTOR_SIZE,
 269                               remaining_sectors * BDRV_SECTOR_SIZE, qiov, 0);
 270         return replication_return_value(s, ret);
 271     }
 272
 273     /*
 274      * Failover failed, only write to active disk if the sectors
 275      * have already been allocated in active disk/hidden disk.
 276      */
 277     qemu_iovec_init(&hd_qiov, qiov->niov);
 278     while (remaining_sectors > 0) {
 279         int64_t count;
 280
 281         ret = bdrv_is_allocated_above(top->bs, base->bs, false,
 282                                       sector_num * BDRV_SECTOR_SIZE,
 283                                       remaining_sectors * BDRV_SECTOR_SIZE,
 284                                       &count);
 285         if (ret < 0) {
 286             goto out1;
 287         }
 288
 289         assert(QEMU_IS_ALIGNED(count, BDRV_SECTOR_SIZE));
 290         n = count >> BDRV_SECTOR_BITS;
 291         qemu_iovec_reset(&hd_qiov);
 292         qemu_iovec_concat(&hd_qiov, qiov, bytes_done, count);
 293
 294         target = ret ? top : base;
 295         ret = bdrv_co_pwritev(target, sector_num * BDRV_SECTOR_SIZE,
 296                               n * BDRV_SECTOR_SIZE, &hd_qiov, 0);
 297         if (ret < 0) {
 298             goto out1;
 299         }
 300
 301         remaining_sectors -= n;
 302         sector_num += n;
 303         bytes_done += count;
 304     }
 305
 306 out1:
 307     qemu_iovec_destroy(&hd_qiov);
 308 out:
 309     return ret;
 310 }
 311
 312 static void secondary_do_checkpoint(BDRVReplicationState *s, Error **errp)
 313 {
 314     Error *local_err = NULL;
 315     int ret;
 316
 317     if (!s->backup_job) {
 318         error_setg(errp, "Backup job was cancelled unexpectedly");
 319         return;
 320     }
 321
 322     backup_do_checkpoint(s->backup_job, &local_err);
 323     if (local_err) {
 324         error_propagate(errp, local_err);
 325         return;
 326     }
 327
 328     if (!s->active_disk->bs->drv) {
 329         error_setg(errp, "Active disk %s is ejected",
 330                    s->active_disk->bs->node_name);
 331         return;
 332     }
 333
 334     ret = s->active_disk->bs->drv->bdrv_make_empty(s->active_disk->bs);
 335     if (ret < 0) {
 336         error_setg(errp, "Cannot make active disk empty");
 337         return;
 338     }
 339
 340     if (!s->hidden_disk->bs->drv) {
 341         error_setg(errp, "Hidden disk %s is ejected",
 342                    s->hidden_disk->bs->node_name);
 343         return;
 344     }
 345
 346     ret = s->hidden_disk->bs->drv->bdrv_make_empty(s->hidden_disk->bs);
 347     if (ret < 0) {
 348         error_setg(errp, "Cannot make hidden disk empty");
 349         return;
 350     }
 351 }
 352
 353 /* This function is supposed to be called twice:
 354  * first with writable = true, then with writable = false.
 355  * The first call puts s->hidden_disk and s->secondary_disk in
 356  * r/w mode, and the second puts them back in their original state.
 357  */
 358 static void reopen_backing_file(BlockDriverState *bs, bool writable,
 359                                 Error **errp)
 360 {
 361     BDRVReplicationState *s = bs->opaque;
 362     BlockReopenQueue *reopen_queue = NULL;
 363     Error *local_err = NULL;
 364
 365     if (writable) {
 366         s->orig_hidden_read_only = bdrv_is_read_only(s->hidden_disk->bs);
 367         s->orig_secondary_read_only = bdrv_is_read_only(s->secondary_disk->bs);
 368     }
 369
 370     bdrv_subtree_drained_begin(s->hidden_disk->bs);
 371     bdrv_subtree_drained_begin(s->secondary_disk->bs);
 372
 373     if (s->orig_hidden_read_only) {
 374         QDict *opts = qdict_new();
 375         qdict_put_bool(opts, BDRV_OPT_READ_ONLY, !writable);
 376         reopen_queue = bdrv_reopen_queue(reopen_queue, s->hidden_disk->bs,
 377                                          opts, true);
 378     }
 379
 380     if (s->orig_secondary_read_only) {
 381         QDict *opts = qdict_new();
 382         qdict_put_bool(opts, BDRV_OPT_READ_ONLY, !writable);
 383         reopen_queue = bdrv_reopen_queue(reopen_queue, s->secondary_disk->bs,
 384                                          opts, true);
 385     }
 386
 387     if (reopen_queue) {
 388         bdrv_reopen_multiple(reopen_queue, &local_err);
 389         error_propagate(errp, local_err);
 390     }
 391
 392     bdrv_subtree_drained_end(s->hidden_disk->bs);
 393     bdrv_subtree_drained_end(s->secondary_disk->bs);
 394 }
 395
 396 static void backup_job_cleanup(BlockDriverState *bs)
 397 {
 398     BDRVReplicationState *s = bs->opaque;
 399     BlockDriverState *top_bs;
 400
 401     top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
 402     if (!top_bs) {
 403         return;
 404     }
 405     bdrv_op_unblock_all(top_bs, s->blocker);
 406     error_free(s->blocker);
 407     reopen_backing_file(bs, false, NULL);
 408 }
 409
 410 static void backup_job_completed(void *opaque, int ret)
 411 {
 412     BlockDriverState *bs = opaque;
 413     BDRVReplicationState *s = bs->opaque;
 414
 415     if (s->stage != BLOCK_REPLICATION_FAILOVER) {
 416         /* The backup job is cancelled unexpectedly */
 417         s->error = -EIO;
 418     }
 419
 420     backup_job_cleanup(bs);
 421 }
 422
 423 static bool check_top_bs(BlockDriverState *top_bs, BlockDriverState *bs)
 424 {
 425     BdrvChild *child;
 426
 427     /* The bs itself is the top_bs */
 428     if (top_bs == bs) {
 429         return true;
 430     }
 431
 432     /* Iterate over top_bs's children */
 433     QLIST_FOREACH(child, &top_bs->children, next) {
 434         if (child->bs == bs || check_top_bs(child->bs, bs)) {
 435             return true;
 436         }
 437     }
 438
 439     return false;
 440 }
 441
 442 static void replication_start(ReplicationState *rs, ReplicationMode mode,
 443                               Error **errp)
 444 {
 445     BlockDriverState *bs = rs->opaque;
 446     BDRVReplicationState *s;
 447     BlockDriverState *top_bs;
 448     int64_t active_length, hidden_length, disk_length;
 449     AioContext *aio_context;
 450     Error *local_err = NULL;
 451
 452     aio_context = bdrv_get_aio_context(bs);
 453     aio_context_acquire(aio_context);
 454     s = bs->opaque;
 455
 456     if (s->stage == BLOCK_REPLICATION_DONE ||
 457         s->stage == BLOCK_REPLICATION_FAILOVER) {
 458         /*
 459          * This case happens when a secondary is promoted to primary.
 460          * Ignore the request because the secondary side of replication
 461          * doesn't have to do anything anymore.
 462          */
 463         aio_context_release(aio_context);
 464         return;
 465     }
 466
 467     if (s->stage != BLOCK_REPLICATION_NONE) {
 468         error_setg(errp, "Block replication is running or done");
 469         aio_context_release(aio_context);
 470         return;
 471     }
 472
 473     if (s->mode != mode) {
 474         error_setg(errp, "The parameter mode's value is invalid, needs %d,"
 475                    " but got %d", s->mode, mode);
 476         aio_context_release(aio_context);
 477         return;
 478     }
 479
 480     switch (s->mode) {
 481     case REPLICATION_MODE_PRIMARY:
 482         break;
 483     case REPLICATION_MODE_SECONDARY:
 484         s->active_disk = bs->file;
 485         if (!s->active_disk || !s->active_disk->bs ||
 486                                     !s->active_disk->bs->backing) {
 487             error_setg(errp, "Active disk doesn't have backing file");
 488             aio_context_release(aio_context);
 489             return;
 490         }
 491
 492         s->hidden_disk = s->active_disk->bs->backing;
 493         if (!s->hidden_disk->bs || !s->hidden_disk->bs->backing) {
 494             error_setg(errp, "Hidden disk doesn't have backing file");
 495             aio_context_release(aio_context);
 496             return;
 497         }
 498
 499         s->secondary_disk = s->hidden_disk->bs->backing;
 500         if (!s->secondary_disk->bs || !bdrv_has_blk(s->secondary_disk->bs)) {
 501             error_setg(errp, "The secondary disk doesn't have block backend");
 502             aio_context_release(aio_context);
 503             return;
 504         }
 505
 506         /* verify the length */
 507         active_length = bdrv_getlength(s->active_disk->bs);
 508         hidden_length = bdrv_getlength(s->hidden_disk->bs);
 509         disk_length = bdrv_getlength(s->secondary_disk->bs);
 510         if (active_length < 0 || hidden_length < 0 || disk_length < 0 ||
 511             active_length != hidden_length || hidden_length != disk_length) {
 512             error_setg(errp, "Active disk, hidden disk, secondary disk's length"
 513                        " are not the same");
 514             aio_context_release(aio_context);
 515             return;
 516         }
 517
 518         /* Must be true, or the bdrv_getlength() calls would have failed */
 519         assert(s->active_disk->bs->drv && s->hidden_disk->bs->drv);
 520
 521         if (!s->active_disk->bs->drv->bdrv_make_empty ||
 522             !s->hidden_disk->bs->drv->bdrv_make_empty) {
 523             error_setg(errp,
 524                        "Active disk or hidden disk doesn't support make_empty");
 525             aio_context_release(aio_context);
 526             return;
 527         }
 528
 529         /* reopen the backing file in r/w mode */
 530         reopen_backing_file(bs, true, &local_err);
 531         if (local_err) {
 532             error_propagate(errp, local_err);
 533             aio_context_release(aio_context);
 534             return;
 535         }
 536
 537         /* start backup job now */
 538         error_setg(&s->blocker,
 539                    "Block device is in use by internal backup job");
 540
 541         top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
 542         if (!top_bs || !bdrv_is_root_node(top_bs) ||
 543             !check_top_bs(top_bs, bs)) {
 544             error_setg(errp, "No top_bs or it is invalid");
 545             reopen_backing_file(bs, false, NULL);
 546             aio_context_release(aio_context);
 547             return;
 548         }
 549         bdrv_op_block_all(top_bs, s->blocker);
 550         bdrv_op_unblock(top_bs, BLOCK_OP_TYPE_DATAPLANE, s->blocker);
 551
 552         s->backup_job = backup_job_create(
 553                                 NULL, s->secondary_disk->bs, s->hidden_disk->bs,
 554                                 0, MIRROR_SYNC_MODE_NONE, NULL, 0, false, NULL,
 555                                 BLOCKDEV_ON_ERROR_REPORT,
 556                                 BLOCKDEV_ON_ERROR_REPORT, JOB_INTERNAL,
 557                                 backup_job_completed, bs, NULL, &local_err);
 558         if (local_err) {
 559             error_propagate(errp, local_err);
 560             backup_job_cleanup(bs);
 561             aio_context_release(aio_context);
 562             return;
 563         }
 564         job_start(&s->backup_job->job);
 565         break;
 566     default:
 567         aio_context_release(aio_context);
 568         abort();
 569     }
 570
 571     s->stage = BLOCK_REPLICATION_RUNNING;
 572
 573     if (s->mode == REPLICATION_MODE_SECONDARY) {
 574         secondary_do_checkpoint(s, errp);
 575     }
 576
 577     s->error = 0;
 578     aio_context_release(aio_context);
 579 }
 580
 581 static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
 582 {
 583     BlockDriverState *bs = rs->opaque;
 584     BDRVReplicationState *s;
 585     AioContext *aio_context;
 586
 587     aio_context = bdrv_get_aio_context(bs);
 588     aio_context_acquire(aio_context);
 589     s = bs->opaque;
 590
 591     if (s->stage == BLOCK_REPLICATION_DONE ||
 592         s->stage == BLOCK_REPLICATION_FAILOVER) {
 593         /*
 594          * This case happens when a secondary was promoted to primary.
 595          * Ignore the request because the secondary side of replication
 596          * doesn't have to do anything anymore.
 597          */
 598         aio_context_release(aio_context);
 599         return;
 600     }
 601
 602     if (s->mode == REPLICATION_MODE_SECONDARY) {
 603         secondary_do_checkpoint(s, errp);
 604     }
 605     aio_context_release(aio_context);
 606 }
 607
 608 static void replication_get_error(ReplicationState *rs, Error **errp)
 609 {
 610     BlockDriverState *bs = rs->opaque;
 611     BDRVReplicationState *s;
 612     AioContext *aio_context;
 613
 614     aio_context = bdrv_get_aio_context(bs);
 615     aio_context_acquire(aio_context);
 616     s = bs->opaque;
 617
 618     if (s->stage == BLOCK_REPLICATION_NONE) {
 619         error_setg(errp, "Block replication is not running");
 620         aio_context_release(aio_context);
 621         return;
 622     }
 623
 624     if (s->error) {
 625         error_setg(errp, "I/O error occurred");
 626         aio_context_release(aio_context);
 627         return;
 628     }
 629     aio_context_release(aio_context);
 630 }
 631
 632 static void replication_done(void *opaque, int ret)
 633 {
 634     BlockDriverState *bs = opaque;
 635     BDRVReplicationState *s = bs->opaque;
 636
 637     if (ret == 0) {
 638         s->stage = BLOCK_REPLICATION_DONE;
 639
 640         s->active_disk = NULL;
 641         s->secondary_disk = NULL;
 642         s->hidden_disk = NULL;
 643         s->error = 0;
 644     } else {
 645         s->stage = BLOCK_REPLICATION_FAILOVER_FAILED;
 646         s->error = -EIO;
 647     }
 648 }
 649
 650 static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
 651 {
 652     BlockDriverState *bs = rs->opaque;
 653     BDRVReplicationState *s;
 654     AioContext *aio_context;
 655
 656     aio_context = bdrv_get_aio_context(bs);
 657     aio_context_acquire(aio_context);
 658     s = bs->opaque;
 659
 660     if (s->stage == BLOCK_REPLICATION_DONE ||
 661         s->stage == BLOCK_REPLICATION_FAILOVER) {
 662         /*
 663          * This case happens when a secondary was promoted to primary.
 664          * Ignore the request because the secondary side of replication
 665          * doesn't have to do anything anymore.
 666          */
 667         aio_context_release(aio_context);
 668         return;
 669     }
 670
 671     if (s->stage != BLOCK_REPLICATION_RUNNING) {
 672         error_setg(errp, "Block replication is not running");
 673         aio_context_release(aio_context);
 674         return;
 675     }
 676
 677     switch (s->mode) {
 678     case REPLICATION_MODE_PRIMARY:
 679         s->stage = BLOCK_REPLICATION_DONE;
 680         s->error = 0;
 681         break;
 682     case REPLICATION_MODE_SECONDARY:
 683         /*
 684          * This BDS will be closed, and the job should be completed
 685          * before the BDS is closed, because we will access hidden
 686          * disk, secondary disk in backup_job_completed().
 687          */
 688         if (s->backup_job) {
 689             job_cancel_sync(&s->backup_job->job);
 690         }
 691
 692         if (!failover) {
 693             secondary_do_checkpoint(s, errp);
 694             s->stage = BLOCK_REPLICATION_DONE;
 695             aio_context_release(aio_context);
 696             return;
 697         }
 698
 699         s->stage = BLOCK_REPLICATION_FAILOVER;
 700         s->commit_job = commit_active_start(
 701                             NULL, s->active_disk->bs, s->secondary_disk->bs,
 702                             JOB_INTERNAL, 0, BLOCKDEV_ON_ERROR_REPORT,
 703                             NULL, replication_done, bs, true, errp);
 704         break;
 705     default:
 706         aio_context_release(aio_context);
 707         abort();
 708     }
 709     aio_context_release(aio_context);
 710 }
 711
 712 static const char *const replication_strong_runtime_opts[] = {
 713     REPLICATION_MODE,
 714     REPLICATION_TOP_ID,
 715
 716     NULL
 717 };
 718
 719 static BlockDriver bdrv_replication = {
 720     .format_name                = "replication",
 721     .instance_size              = sizeof(BDRVReplicationState),
 722
 723     .bdrv_open                  = replication_open,
 724     .bdrv_close                 = replication_close,
 725     .bdrv_child_perm            = replication_child_perm,
 726
 727     .bdrv_getlength             = replication_getlength,
 728     .bdrv_co_readv              = replication_co_readv,
 729     .bdrv_co_writev             = replication_co_writev,
 730
 731     .is_filter                  = true,
 732
 733     .has_variable_length        = true,
 734     .strong_runtime_opts        = replication_strong_runtime_opts,
 735 };
 736
 737 static void bdrv_replication_init(void)
 738 {
 739     bdrv_register(&bdrv_replication);
 740 }
 741
 742 block_init(bdrv_replication_init);