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 "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 replication_co_getlength(BlockDriverState *bs)
 183 {
 184     return bdrv_co_getlength(bs->file->bs);
 185 }
 186
 187 static int replication_get_io_status(BDRVReplicationState *s)
 188 {
 189     switch (s->stage) {
 190     case BLOCK_REPLICATION_NONE:
 191         return -EIO;
 192     case BLOCK_REPLICATION_RUNNING:
 193         return 0;
 194     case BLOCK_REPLICATION_FAILOVER:
 195         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
 196     case BLOCK_REPLICATION_FAILOVER_FAILED:
 197         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 1;
 198     case BLOCK_REPLICATION_DONE:
 199         /*
 200          * active commit job completes, and active disk and secondary_disk
 201          * is swapped, so we can operate bs->file directly
 202          */
 203         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
 204     default:
 205         abort();
 206     }
 207 }
 208
 209 static int replication_return_value(BDRVReplicationState *s, int ret)
 210 {
 211     if (s->mode == REPLICATION_MODE_SECONDARY) {
 212         return ret;
 213     }
 214
 215     if (ret < 0) {
 216         s->error = ret;
 217         ret = 0;
 218     }
 219
 220     return ret;
 221 }
 222
 223 static int coroutine_fn GRAPH_RDLOCK
 224 replication_co_readv(BlockDriverState *bs, int64_t sector_num,
 225                      int remaining_sectors, 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 int coroutine_fn GRAPH_RDLOCK
 247 replication_co_writev(BlockDriverState *bs, int64_t sector_num,
 248                       int remaining_sectors, QEMUIOVector *qiov, int flags)
 249 {
 250     BDRVReplicationState *s = bs->opaque;
 251     QEMUIOVector hd_qiov;
 252     uint64_t bytes_done = 0;
 253     BdrvChild *top = bs->file;
 254     BdrvChild *base = s->secondary_disk;
 255     BdrvChild *target;
 256     int ret;
 257     int64_t n;
 258
 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 void secondary_do_checkpoint(BlockDriverState *bs, Error **errp)
 310 {
 311     BDRVReplicationState *s = bs->opaque;
 312     BdrvChild *active_disk = bs->file;
 313     Error *local_err = NULL;
 314     int ret;
 315
 316     if (!s->backup_job) {
 317         error_setg(errp, "Backup job was cancelled unexpectedly");
 318         return;
 319     }
 320
 321     backup_do_checkpoint(s->backup_job, &local_err);
 322     if (local_err) {
 323         error_propagate(errp, local_err);
 324         return;
 325     }
 326
 327     if (!active_disk->bs->drv) {
 328         error_setg(errp, "Active disk %s is ejected",
 329                    active_disk->bs->node_name);
 330         return;
 331     }
 332
 333     ret = bdrv_make_empty(active_disk, errp);
 334     if (ret < 0) {
 335         return;
 336     }
 337
 338     if (!s->hidden_disk->bs->drv) {
 339         error_setg(errp, "Hidden disk %s is ejected",
 340                    s->hidden_disk->bs->node_name);
 341         return;
 342     }
 343
 344     ret = bdrv_make_empty(s->hidden_disk, errp);
 345     if (ret < 0) {
 346         return;
 347     }
 348 }
 349
 350 /* This function is supposed to be called twice:
 351  * first with writable = true, then with writable = false.
 352  * The first call puts s->hidden_disk and s->secondary_disk in
 353  * r/w mode, and the second puts them back in their original state.
 354  */
 355 static void reopen_backing_file(BlockDriverState *bs, bool writable,
 356                                 Error **errp)
 357 {
 358     BDRVReplicationState *s = bs->opaque;
 359     BdrvChild *hidden_disk, *secondary_disk;
 360     BlockReopenQueue *reopen_queue = NULL;
 361
 362     /*
 363      * s->hidden_disk and s->secondary_disk may not be set yet, as they will
 364      * only be set after the children are writable.
 365      */
 366     hidden_disk = bs->file->bs->backing;
 367     secondary_disk = hidden_disk->bs->backing;
 368
 369     if (writable) {
 370         s->orig_hidden_read_only = bdrv_is_read_only(hidden_disk->bs);
 371         s->orig_secondary_read_only = bdrv_is_read_only(secondary_disk->bs);
 372     }
 373
 374     if (s->orig_hidden_read_only) {
 375         QDict *opts = qdict_new();
 376         qdict_put_bool(opts, BDRV_OPT_READ_ONLY, !writable);
 377         reopen_queue = bdrv_reopen_queue(reopen_queue, hidden_disk->bs,
 378                                          opts, true);
 379     }
 380
 381     if (s->orig_secondary_read_only) {
 382         QDict *opts = qdict_new();
 383         qdict_put_bool(opts, BDRV_OPT_READ_ONLY, !writable);
 384         reopen_queue = bdrv_reopen_queue(reopen_queue, secondary_disk->bs,
 385                                          opts, true);
 386     }
 387
 388     if (reopen_queue) {
 389         AioContext *ctx = bdrv_get_aio_context(bs);
 390         if (ctx != qemu_get_aio_context()) {
 391             aio_context_release(ctx);
 392         }
 393         bdrv_reopen_multiple(reopen_queue, errp);
 394         if (ctx != qemu_get_aio_context()) {
 395             aio_context_acquire(ctx);
 396         }
 397     }
 398 }
 399
 400 static void backup_job_cleanup(BlockDriverState *bs)
 401 {
 402     BDRVReplicationState *s = bs->opaque;
 403     BlockDriverState *top_bs;
 404
 405     s->backup_job = NULL;
 406
 407     top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
 408     if (!top_bs) {
 409         return;
 410     }
 411     bdrv_op_unblock_all(top_bs, s->blocker);
 412     error_free(s->blocker);
 413     reopen_backing_file(bs, false, NULL);
 414 }
 415
 416 static void backup_job_completed(void *opaque, int ret)
 417 {
 418     BlockDriverState *bs = opaque;
 419     BDRVReplicationState *s = bs->opaque;
 420
 421     if (s->stage != BLOCK_REPLICATION_FAILOVER) {
 422         /* The backup job is cancelled unexpectedly */
 423         s->error = -EIO;
 424     }
 425
 426     backup_job_cleanup(bs);
 427 }
 428
 429 static bool check_top_bs(BlockDriverState *top_bs, BlockDriverState *bs)
 430 {
 431     BdrvChild *child;
 432
 433     /* The bs itself is the top_bs */
 434     if (top_bs == bs) {
 435         return true;
 436     }
 437
 438     /* Iterate over top_bs's children */
 439     QLIST_FOREACH(child, &top_bs->children, next) {
 440         if (child->bs == bs || check_top_bs(child->bs, bs)) {
 441             return true;
 442         }
 443     }
 444
 445     return false;
 446 }
 447
 448 static void replication_start(ReplicationState *rs, ReplicationMode mode,
 449                               Error **errp)
 450 {
 451     BlockDriverState *bs = rs->opaque;
 452     BDRVReplicationState *s;
 453     BlockDriverState *top_bs;
 454     BdrvChild *active_disk, *hidden_disk, *secondary_disk;
 455     int64_t active_length, hidden_length, disk_length;
 456     AioContext *aio_context;
 457     Error *local_err = NULL;
 458     BackupPerf perf = { .use_copy_range = true, .max_workers = 1 };
 459
 460     aio_context = bdrv_get_aio_context(bs);
 461     aio_context_acquire(aio_context);
 462     s = bs->opaque;
 463
 464     if (s->stage == BLOCK_REPLICATION_DONE ||
 465         s->stage == BLOCK_REPLICATION_FAILOVER) {
 466         /*
 467          * This case happens when a secondary is promoted to primary.
 468          * Ignore the request because the secondary side of replication
 469          * doesn't have to do anything anymore.
 470          */
 471         aio_context_release(aio_context);
 472         return;
 473     }
 474
 475     if (s->stage != BLOCK_REPLICATION_NONE) {
 476         error_setg(errp, "Block replication is running or done");
 477         aio_context_release(aio_context);
 478         return;
 479     }
 480
 481     if (s->mode != mode) {
 482         error_setg(errp, "The parameter mode's value is invalid, needs %d,"
 483                    " but got %d", s->mode, mode);
 484         aio_context_release(aio_context);
 485         return;
 486     }
 487
 488     switch (s->mode) {
 489     case REPLICATION_MODE_PRIMARY:
 490         break;
 491     case REPLICATION_MODE_SECONDARY:
 492         active_disk = bs->file;
 493         if (!active_disk || !active_disk->bs || !active_disk->bs->backing) {
 494             error_setg(errp, "Active disk doesn't have backing file");
 495             aio_context_release(aio_context);
 496             return;
 497         }
 498
 499         hidden_disk = active_disk->bs->backing;
 500         if (!hidden_disk->bs || !hidden_disk->bs->backing) {
 501             error_setg(errp, "Hidden disk doesn't have backing file");
 502             aio_context_release(aio_context);
 503             return;
 504         }
 505
 506         secondary_disk = hidden_disk->bs->backing;
 507         if (!secondary_disk->bs || !bdrv_has_blk(secondary_disk->bs)) {
 508             error_setg(errp, "The secondary disk doesn't have block backend");
 509             aio_context_release(aio_context);
 510             return;
 511         }
 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             aio_context_release(aio_context);
 522             return;
 523         }
 524
 525         /* Must be true, or the bdrv_getlength() calls would have failed */
 526         assert(active_disk->bs->drv && hidden_disk->bs->drv);
 527
 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             aio_context_release(aio_context);
 533             return;
 534         }
 535
 536         /* reopen the backing file in r/w mode */
 537         reopen_backing_file(bs, true, &local_err);
 538         if (local_err) {
 539             error_propagate(errp, local_err);
 540             aio_context_release(aio_context);
 541             return;
 542         }
 543
 544         bdrv_ref(hidden_disk->bs);
 545         s->hidden_disk = bdrv_attach_child(bs, hidden_disk->bs, "hidden disk",
 546                                            &child_of_bds, BDRV_CHILD_DATA,
 547                                            &local_err);
 548         if (local_err) {
 549             error_propagate(errp, local_err);
 550             aio_context_release(aio_context);
 551             return;
 552         }
 553
 554         bdrv_ref(secondary_disk->bs);
 555         s->secondary_disk = bdrv_attach_child(bs, secondary_disk->bs,
 556                                               "secondary disk", &child_of_bds,
 557                                               BDRV_CHILD_DATA, &local_err);
 558         if (local_err) {
 559             error_propagate(errp, local_err);
 560             aio_context_release(aio_context);
 561             return;
 562         }
 563
 564         /* start backup job now */
 565         error_setg(&s->blocker,
 566                    "Block device is in use by internal backup job");
 567
 568         top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
 569         if (!top_bs || !bdrv_is_root_node(top_bs) ||
 570             !check_top_bs(top_bs, bs)) {
 571             error_setg(errp, "No top_bs or it is invalid");
 572             reopen_backing_file(bs, false, NULL);
 573             aio_context_release(aio_context);
 574             return;
 575         }
 576         bdrv_op_block_all(top_bs, s->blocker);
 577         bdrv_op_unblock(top_bs, BLOCK_OP_TYPE_DATAPLANE, s->blocker);
 578
 579         s->backup_job = backup_job_create(
 580                                 NULL, s->secondary_disk->bs, s->hidden_disk->bs,
 581                                 0, MIRROR_SYNC_MODE_NONE, NULL, 0, false, NULL,
 582                                 &perf,
 583                                 BLOCKDEV_ON_ERROR_REPORT,
 584                                 BLOCKDEV_ON_ERROR_REPORT, JOB_INTERNAL,
 585                                 backup_job_completed, bs, NULL, &local_err);
 586         if (local_err) {
 587             error_propagate(errp, local_err);
 588             backup_job_cleanup(bs);
 589             aio_context_release(aio_context);
 590             return;
 591         }
 592         job_start(&s->backup_job->job);
 593         break;
 594     default:
 595         aio_context_release(aio_context);
 596         abort();
 597     }
 598
 599     s->stage = BLOCK_REPLICATION_RUNNING;
 600
 601     if (s->mode == REPLICATION_MODE_SECONDARY) {
 602         secondary_do_checkpoint(bs, errp);
 603     }
 604
 605     s->error = 0;
 606     aio_context_release(aio_context);
 607 }
 608
 609 static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
 610 {
 611     BlockDriverState *bs = rs->opaque;
 612     BDRVReplicationState *s;
 613     AioContext *aio_context;
 614
 615     aio_context = bdrv_get_aio_context(bs);
 616     aio_context_acquire(aio_context);
 617     s = bs->opaque;
 618
 619     if (s->stage == BLOCK_REPLICATION_DONE ||
 620         s->stage == BLOCK_REPLICATION_FAILOVER) {
 621         /*
 622          * This case happens when a secondary was promoted to primary.
 623          * Ignore the request because the secondary side of replication
 624          * doesn't have to do anything anymore.
 625          */
 626         aio_context_release(aio_context);
 627         return;
 628     }
 629
 630     if (s->mode == REPLICATION_MODE_SECONDARY) {
 631         secondary_do_checkpoint(bs, errp);
 632     }
 633     aio_context_release(aio_context);
 634 }
 635
 636 static void replication_get_error(ReplicationState *rs, Error **errp)
 637 {
 638     BlockDriverState *bs = rs->opaque;
 639     BDRVReplicationState *s;
 640     AioContext *aio_context;
 641
 642     aio_context = bdrv_get_aio_context(bs);
 643     aio_context_acquire(aio_context);
 644     s = bs->opaque;
 645
 646     if (s->stage == BLOCK_REPLICATION_NONE) {
 647         error_setg(errp, "Block replication is not running");
 648         aio_context_release(aio_context);
 649         return;
 650     }
 651
 652     if (s->error) {
 653         error_setg(errp, "I/O error occurred");
 654         aio_context_release(aio_context);
 655         return;
 656     }
 657     aio_context_release(aio_context);
 658 }
 659
 660 static void replication_done(void *opaque, int ret)
 661 {
 662     BlockDriverState *bs = opaque;
 663     BDRVReplicationState *s = bs->opaque;
 664
 665     if (ret == 0) {
 666         s->stage = BLOCK_REPLICATION_DONE;
 667
 668         bdrv_unref_child(bs, s->secondary_disk);
 669         s->secondary_disk = NULL;
 670         bdrv_unref_child(bs, s->hidden_disk);
 671         s->hidden_disk = NULL;
 672         s->error = 0;
 673     } else {
 674         s->stage = BLOCK_REPLICATION_FAILOVER_FAILED;
 675         s->error = -EIO;
 676     }
 677 }
 678
 679 static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
 680 {
 681     BlockDriverState *bs = rs->opaque;
 682     BDRVReplicationState *s;
 683     AioContext *aio_context;
 684
 685     aio_context = bdrv_get_aio_context(bs);
 686     aio_context_acquire(aio_context);
 687     s = bs->opaque;
 688
 689     if (s->stage == BLOCK_REPLICATION_DONE ||
 690         s->stage == BLOCK_REPLICATION_FAILOVER) {
 691         /*
 692          * This case happens when a secondary was promoted to primary.
 693          * Ignore the request because the secondary side of replication
 694          * doesn't have to do anything anymore.
 695          */
 696         aio_context_release(aio_context);
 697         return;
 698     }
 699
 700     if (s->stage != BLOCK_REPLICATION_RUNNING) {
 701         error_setg(errp, "Block replication is not running");
 702         aio_context_release(aio_context);
 703         return;
 704     }
 705
 706     switch (s->mode) {
 707     case REPLICATION_MODE_PRIMARY:
 708         s->stage = BLOCK_REPLICATION_DONE;
 709         s->error = 0;
 710         break;
 711     case REPLICATION_MODE_SECONDARY:
 712         /*
 713          * This BDS will be closed, and the job should be completed
 714          * before the BDS is closed, because we will access hidden
 715          * disk, secondary disk in backup_job_completed().
 716          */
 717         if (s->backup_job) {
 718             aio_context_release(aio_context);
 719             job_cancel_sync(&s->backup_job->job, true);
 720             aio_context_acquire(aio_context);
 721         }
 722
 723         if (!failover) {
 724             secondary_do_checkpoint(bs, errp);
 725             s->stage = BLOCK_REPLICATION_DONE;
 726             aio_context_release(aio_context);
 727             return;
 728         }
 729
 730         s->stage = BLOCK_REPLICATION_FAILOVER;
 731         s->commit_job = commit_active_start(
 732                             NULL, bs->file->bs, s->secondary_disk->bs,
 733                             JOB_INTERNAL, 0, BLOCKDEV_ON_ERROR_REPORT,
 734                             NULL, replication_done, bs, true, errp);
 735         break;
 736     default:
 737         aio_context_release(aio_context);
 738         abort();
 739     }
 740     aio_context_release(aio_context);
 741 }
 742
 743 static const char *const replication_strong_runtime_opts[] = {
 744     REPLICATION_MODE,
 745     REPLICATION_TOP_ID,
 746
 747     NULL
 748 };
 749
 750 static BlockDriver bdrv_replication = {
 751     .format_name                = "replication",
 752     .instance_size              = sizeof(BDRVReplicationState),
 753
 754     .bdrv_open                  = replication_open,
 755     .bdrv_close                 = replication_close,
 756     .bdrv_child_perm            = replication_child_perm,
 757
 758     .bdrv_co_getlength          = replication_co_getlength,
 759     .bdrv_co_readv              = replication_co_readv,
 760     .bdrv_co_writev             = replication_co_writev,
 761
 762     .is_filter                  = true,
 763
 764     .has_variable_length        = true,
 765     .strong_runtime_opts        = replication_strong_runtime_opts,
 766 };
 767
 768 static void bdrv_replication_init(void)
 769 {
 770     bdrv_register(&bdrv_replication);
 771 }
 772
 773 block_init(bdrv_replication_init);