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-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 struct BDRVReplicationState {
  26     ReplicationMode mode;
  27     int replication_state;
  28     BdrvChild *active_disk;
  29     BdrvChild *hidden_disk;
  30     BdrvChild *secondary_disk;
  31     char *top_id;
  32     ReplicationState *rs;
  33     Error *blocker;
  34     int orig_hidden_flags;
  35     int orig_secondary_flags;
  36     int error;
  37 } BDRVReplicationState;
  38
  39 enum {
  40     BLOCK_REPLICATION_NONE,             /* block replication is not started */
  41     BLOCK_REPLICATION_RUNNING,          /* block replication is running */
  42     BLOCK_REPLICATION_FAILOVER,         /* failover is running in background */
  43     BLOCK_REPLICATION_FAILOVER_FAILED,  /* failover failed */
  44     BLOCK_REPLICATION_DONE,             /* block replication is done */
  45 };
  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     ret = -EINVAL;
  90     opts = qemu_opts_create(&replication_runtime_opts, NULL, 0, &error_abort);
  91     qemu_opts_absorb_qdict(opts, options, &local_err);
  92     if (local_err) {
  93         goto fail;
  94     }
  95
  96     mode = qemu_opt_get(opts, REPLICATION_MODE);
  97     if (!mode) {
  98         error_setg(&local_err, "Missing the option mode");
  99         goto fail;
 100     }
 101
 102     if (!strcmp(mode, "primary")) {
 103         s->mode = REPLICATION_MODE_PRIMARY;
 104         top_id = qemu_opt_get(opts, REPLICATION_TOP_ID);
 105         if (top_id) {
 106             error_setg(&local_err, "The primary side does not support option top-id");
 107             goto fail;
 108         }
 109     } else if (!strcmp(mode, "secondary")) {
 110         s->mode = REPLICATION_MODE_SECONDARY;
 111         top_id = qemu_opt_get(opts, REPLICATION_TOP_ID);
 112         s->top_id = g_strdup(top_id);
 113         if (!s->top_id) {
 114             error_setg(&local_err, "Missing the option top-id");
 115             goto fail;
 116         }
 117     } else {
 118         error_setg(&local_err,
 119                    "The option mode's value should be primary or secondary");
 120         goto fail;
 121     }
 122
 123     s->rs = replication_new(bs, &replication_ops);
 124
 125     ret = 0;
 126
 127 fail:
 128     qemu_opts_del(opts);
 129     error_propagate(errp, local_err);
 130
 131     return ret;
 132 }
 133
 134 static void replication_close(BlockDriverState *bs)
 135 {
 136     BDRVReplicationState *s = bs->opaque;
 137
 138     if (s->replication_state == BLOCK_REPLICATION_RUNNING) {
 139         replication_stop(s->rs, false, NULL);
 140     }
 141     if (s->replication_state == BLOCK_REPLICATION_FAILOVER) {
 142         block_job_cancel_sync(s->active_disk->bs->job);
 143     }
 144
 145     if (s->mode == REPLICATION_MODE_SECONDARY) {
 146         g_free(s->top_id);
 147     }
 148
 149     replication_remove(s->rs);
 150 }
 151
 152 static int64_t replication_getlength(BlockDriverState *bs)
 153 {
 154     return bdrv_getlength(bs->file->bs);
 155 }
 156
 157 static int replication_get_io_status(BDRVReplicationState *s)
 158 {
 159     switch (s->replication_state) {
 160     case BLOCK_REPLICATION_NONE:
 161         return -EIO;
 162     case BLOCK_REPLICATION_RUNNING:
 163         return 0;
 164     case BLOCK_REPLICATION_FAILOVER:
 165         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
 166     case BLOCK_REPLICATION_FAILOVER_FAILED:
 167         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 1;
 168     case BLOCK_REPLICATION_DONE:
 169         /*
 170          * active commit job completes, and active disk and secondary_disk
 171          * is swapped, so we can operate bs->file directly
 172          */
 173         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
 174     default:
 175         abort();
 176     }
 177 }
 178
 179 static int replication_return_value(BDRVReplicationState *s, int ret)
 180 {
 181     if (s->mode == REPLICATION_MODE_SECONDARY) {
 182         return ret;
 183     }
 184
 185     if (ret < 0) {
 186         s->error = ret;
 187         ret = 0;
 188     }
 189
 190     return ret;
 191 }
 192
 193 static coroutine_fn int replication_co_readv(BlockDriverState *bs,
 194                                              int64_t sector_num,
 195                                              int remaining_sectors,
 196                                              QEMUIOVector *qiov)
 197 {
 198     BDRVReplicationState *s = bs->opaque;
 199     BdrvChild *child = s->secondary_disk;
 200     BlockJob *job = NULL;
 201     CowRequest req;
 202     int ret;
 203
 204     if (s->mode == REPLICATION_MODE_PRIMARY) {
 205         /* We only use it to forward primary write requests */
 206         return -EIO;
 207     }
 208
 209     ret = replication_get_io_status(s);
 210     if (ret < 0) {
 211         return ret;
 212     }
 213
 214     if (child && child->bs) {
 215         job = child->bs->job;
 216     }
 217
 218     if (job) {
 219         backup_wait_for_overlapping_requests(child->bs->job, sector_num,
 220                                              remaining_sectors);
 221         backup_cow_request_begin(&req, child->bs->job, sector_num,
 222                                  remaining_sectors);
 223         ret = bdrv_co_readv(bs->file, sector_num, remaining_sectors,
 224                             qiov);
 225         backup_cow_request_end(&req);
 226         goto out;
 227     }
 228
 229     ret = bdrv_co_readv(bs->file, sector_num, remaining_sectors, qiov);
 230 out:
 231     return replication_return_value(s, ret);
 232 }
 233
 234 static coroutine_fn int replication_co_writev(BlockDriverState *bs,
 235                                               int64_t sector_num,
 236                                               int remaining_sectors,
 237                                               QEMUIOVector *qiov)
 238 {
 239     BDRVReplicationState *s = bs->opaque;
 240     QEMUIOVector hd_qiov;
 241     uint64_t bytes_done = 0;
 242     BdrvChild *top = bs->file;
 243     BdrvChild *base = s->secondary_disk;
 244     BdrvChild *target;
 245     int ret, n;
 246
 247     ret = replication_get_io_status(s);
 248     if (ret < 0) {
 249         goto out;
 250     }
 251
 252     if (ret == 0) {
 253         ret = bdrv_co_writev(top, sector_num,
 254                              remaining_sectors, qiov);
 255         return replication_return_value(s, ret);
 256     }
 257
 258     /*
 259      * Failover failed, only write to active disk if the sectors
 260      * have already been allocated in active disk/hidden disk.
 261      */
 262     qemu_iovec_init(&hd_qiov, qiov->niov);
 263     while (remaining_sectors > 0) {
 264         ret = bdrv_is_allocated_above(top->bs, base->bs, sector_num,
 265                                       remaining_sectors, &n);
 266         if (ret < 0) {
 267             goto out1;
 268         }
 269
 270         qemu_iovec_reset(&hd_qiov);
 271         qemu_iovec_concat(&hd_qiov, qiov, bytes_done, n * BDRV_SECTOR_SIZE);
 272
 273         target = ret ? top : base;
 274         ret = bdrv_co_writev(target, sector_num, n, &hd_qiov);
 275         if (ret < 0) {
 276             goto out1;
 277         }
 278
 279         remaining_sectors -= n;
 280         sector_num += n;
 281         bytes_done += n * BDRV_SECTOR_SIZE;
 282     }
 283
 284 out1:
 285     qemu_iovec_destroy(&hd_qiov);
 286 out:
 287     return ret;
 288 }
 289
 290 static bool replication_recurse_is_first_non_filter(BlockDriverState *bs,
 291                                                     BlockDriverState *candidate)
 292 {
 293     return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
 294 }
 295
 296 static void secondary_do_checkpoint(BDRVReplicationState *s, Error **errp)
 297 {
 298     Error *local_err = NULL;
 299     int ret;
 300
 301     if (!s->secondary_disk->bs->job) {
 302         error_setg(errp, "Backup job was cancelled unexpectedly");
 303         return;
 304     }
 305
 306     backup_do_checkpoint(s->secondary_disk->bs->job, &local_err);
 307     if (local_err) {
 308         error_propagate(errp, local_err);
 309         return;
 310     }
 311
 312     ret = s->active_disk->bs->drv->bdrv_make_empty(s->active_disk->bs);
 313     if (ret < 0) {
 314         error_setg(errp, "Cannot make active disk empty");
 315         return;
 316     }
 317
 318     ret = s->hidden_disk->bs->drv->bdrv_make_empty(s->hidden_disk->bs);
 319     if (ret < 0) {
 320         error_setg(errp, "Cannot make hidden disk empty");
 321         return;
 322     }
 323 }
 324
 325 static void reopen_backing_file(BlockDriverState *bs, bool writable,
 326                                 Error **errp)
 327 {
 328     BDRVReplicationState *s = bs->opaque;
 329     BlockReopenQueue *reopen_queue = NULL;
 330     int orig_hidden_flags, orig_secondary_flags;
 331     int new_hidden_flags, new_secondary_flags;
 332     Error *local_err = NULL;
 333
 334     if (writable) {
 335         orig_hidden_flags = s->orig_hidden_flags =
 336                                 bdrv_get_flags(s->hidden_disk->bs);
 337         new_hidden_flags = (orig_hidden_flags | BDRV_O_RDWR) &
 338                                                     ~BDRV_O_INACTIVE;
 339         orig_secondary_flags = s->orig_secondary_flags =
 340                                 bdrv_get_flags(s->secondary_disk->bs);
 341         new_secondary_flags = (orig_secondary_flags | BDRV_O_RDWR) &
 342                                                      ~BDRV_O_INACTIVE;
 343     } else {
 344         orig_hidden_flags = (s->orig_hidden_flags | BDRV_O_RDWR) &
 345                                                     ~BDRV_O_INACTIVE;
 346         new_hidden_flags = s->orig_hidden_flags;
 347         orig_secondary_flags = (s->orig_secondary_flags | BDRV_O_RDWR) &
 348                                                     ~BDRV_O_INACTIVE;
 349         new_secondary_flags = s->orig_secondary_flags;
 350     }
 351
 352     if (orig_hidden_flags != new_hidden_flags) {
 353         reopen_queue = bdrv_reopen_queue(reopen_queue, s->hidden_disk->bs, NULL,
 354                                          new_hidden_flags);
 355     }
 356
 357     if (!(orig_secondary_flags & BDRV_O_RDWR)) {
 358         reopen_queue = bdrv_reopen_queue(reopen_queue, s->secondary_disk->bs,
 359                                          NULL, new_secondary_flags);
 360     }
 361
 362     if (reopen_queue) {
 363         bdrv_reopen_multiple(bdrv_get_aio_context(bs),
 364                              reopen_queue, &local_err);
 365         error_propagate(errp, local_err);
 366     }
 367 }
 368
 369 static void backup_job_cleanup(BlockDriverState *bs)
 370 {
 371     BDRVReplicationState *s = bs->opaque;
 372     BlockDriverState *top_bs;
 373
 374     top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
 375     if (!top_bs) {
 376         return;
 377     }
 378     bdrv_op_unblock_all(top_bs, s->blocker);
 379     error_free(s->blocker);
 380     reopen_backing_file(bs, false, NULL);
 381 }
 382
 383 static void backup_job_completed(void *opaque, int ret)
 384 {
 385     BlockDriverState *bs = opaque;
 386     BDRVReplicationState *s = bs->opaque;
 387
 388     if (s->replication_state != BLOCK_REPLICATION_FAILOVER) {
 389         /* The backup job is cancelled unexpectedly */
 390         s->error = -EIO;
 391     }
 392
 393     backup_job_cleanup(bs);
 394 }
 395
 396 static bool check_top_bs(BlockDriverState *top_bs, BlockDriverState *bs)
 397 {
 398     BdrvChild *child;
 399
 400     /* The bs itself is the top_bs */
 401     if (top_bs == bs) {
 402         return true;
 403     }
 404
 405     /* Iterate over top_bs's children */
 406     QLIST_FOREACH(child, &top_bs->children, next) {
 407         if (child->bs == bs || check_top_bs(child->bs, bs)) {
 408             return true;
 409         }
 410     }
 411
 412     return false;
 413 }
 414
 415 static void replication_start(ReplicationState *rs, ReplicationMode mode,
 416                               Error **errp)
 417 {
 418     BlockDriverState *bs = rs->opaque;
 419     BDRVReplicationState *s;
 420     BlockDriverState *top_bs;
 421     int64_t active_length, hidden_length, disk_length;
 422     AioContext *aio_context;
 423     Error *local_err = NULL;
 424
 425     aio_context = bdrv_get_aio_context(bs);
 426     aio_context_acquire(aio_context);
 427     s = bs->opaque;
 428
 429     if (s->replication_state != BLOCK_REPLICATION_NONE) {
 430         error_setg(errp, "Block replication is running or done");
 431         aio_context_release(aio_context);
 432         return;
 433     }
 434
 435     if (s->mode != mode) {
 436         error_setg(errp, "The parameter mode's value is invalid, needs %d,"
 437                    " but got %d", s->mode, mode);
 438         aio_context_release(aio_context);
 439         return;
 440     }
 441
 442     switch (s->mode) {
 443     case REPLICATION_MODE_PRIMARY:
 444         break;
 445     case REPLICATION_MODE_SECONDARY:
 446         s->active_disk = bs->file;
 447         if (!s->active_disk || !s->active_disk->bs ||
 448                                     !s->active_disk->bs->backing) {
 449             error_setg(errp, "Active disk doesn't have backing file");
 450             aio_context_release(aio_context);
 451             return;
 452         }
 453
 454         s->hidden_disk = s->active_disk->bs->backing;
 455         if (!s->hidden_disk->bs || !s->hidden_disk->bs->backing) {
 456             error_setg(errp, "Hidden disk doesn't have backing file");
 457             aio_context_release(aio_context);
 458             return;
 459         }
 460
 461         s->secondary_disk = s->hidden_disk->bs->backing;
 462         if (!s->secondary_disk->bs || !bdrv_has_blk(s->secondary_disk->bs)) {
 463             error_setg(errp, "The secondary disk doesn't have block backend");
 464             aio_context_release(aio_context);
 465             return;
 466         }
 467
 468         /* verify the length */
 469         active_length = bdrv_getlength(s->active_disk->bs);
 470         hidden_length = bdrv_getlength(s->hidden_disk->bs);
 471         disk_length = bdrv_getlength(s->secondary_disk->bs);
 472         if (active_length < 0 || hidden_length < 0 || disk_length < 0 ||
 473             active_length != hidden_length || hidden_length != disk_length) {
 474             error_setg(errp, "Active disk, hidden disk, secondary disk's length"
 475                        " are not the same");
 476             aio_context_release(aio_context);
 477             return;
 478         }
 479
 480         if (!s->active_disk->bs->drv->bdrv_make_empty ||
 481             !s->hidden_disk->bs->drv->bdrv_make_empty) {
 482             error_setg(errp,
 483                        "Active disk or hidden disk doesn't support make_empty");
 484             aio_context_release(aio_context);
 485             return;
 486         }
 487
 488         /* reopen the backing file in r/w mode */
 489         reopen_backing_file(bs, true, &local_err);
 490         if (local_err) {
 491             error_propagate(errp, local_err);
 492             aio_context_release(aio_context);
 493             return;
 494         }
 495
 496         /* start backup job now */
 497         error_setg(&s->blocker,
 498                    "Block device is in use by internal backup job");
 499
 500         top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
 501         if (!top_bs || !bdrv_is_root_node(top_bs) ||
 502             !check_top_bs(top_bs, bs)) {
 503             error_setg(errp, "No top_bs or it is invalid");
 504             reopen_backing_file(bs, false, NULL);
 505             aio_context_release(aio_context);
 506             return;
 507         }
 508         bdrv_op_block_all(top_bs, s->blocker);
 509         bdrv_op_unblock(top_bs, BLOCK_OP_TYPE_DATAPLANE, s->blocker);
 510
 511         backup_start("replication-backup", s->secondary_disk->bs,
 512                      s->hidden_disk->bs, 0, MIRROR_SYNC_MODE_NONE, NULL, false,
 513                      BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT,
 514                      backup_job_completed, bs, NULL, &local_err);
 515         if (local_err) {
 516             error_propagate(errp, local_err);
 517             backup_job_cleanup(bs);
 518             aio_context_release(aio_context);
 519             return;
 520         }
 521         break;
 522     default:
 523         aio_context_release(aio_context);
 524         abort();
 525     }
 526
 527     s->replication_state = BLOCK_REPLICATION_RUNNING;
 528
 529     if (s->mode == REPLICATION_MODE_SECONDARY) {
 530         secondary_do_checkpoint(s, errp);
 531     }
 532
 533     s->error = 0;
 534     aio_context_release(aio_context);
 535 }
 536
 537 static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
 538 {
 539     BlockDriverState *bs = rs->opaque;
 540     BDRVReplicationState *s;
 541     AioContext *aio_context;
 542
 543     aio_context = bdrv_get_aio_context(bs);
 544     aio_context_acquire(aio_context);
 545     s = bs->opaque;
 546
 547     if (s->mode == REPLICATION_MODE_SECONDARY) {
 548         secondary_do_checkpoint(s, errp);
 549     }
 550     aio_context_release(aio_context);
 551 }
 552
 553 static void replication_get_error(ReplicationState *rs, Error **errp)
 554 {
 555     BlockDriverState *bs = rs->opaque;
 556     BDRVReplicationState *s;
 557     AioContext *aio_context;
 558
 559     aio_context = bdrv_get_aio_context(bs);
 560     aio_context_acquire(aio_context);
 561     s = bs->opaque;
 562
 563     if (s->replication_state != BLOCK_REPLICATION_RUNNING) {
 564         error_setg(errp, "Block replication is not running");
 565         aio_context_release(aio_context);
 566         return;
 567     }
 568
 569     if (s->error) {
 570         error_setg(errp, "I/O error occurred");
 571         aio_context_release(aio_context);
 572         return;
 573     }
 574     aio_context_release(aio_context);
 575 }
 576
 577 static void replication_done(void *opaque, int ret)
 578 {
 579     BlockDriverState *bs = opaque;
 580     BDRVReplicationState *s = bs->opaque;
 581
 582     if (ret == 0) {
 583         s->replication_state = BLOCK_REPLICATION_DONE;
 584
 585         /* refresh top bs's filename */
 586         bdrv_refresh_filename(bs);
 587         s->active_disk = NULL;
 588         s->secondary_disk = NULL;
 589         s->hidden_disk = NULL;
 590         s->error = 0;
 591     } else {
 592         s->replication_state = BLOCK_REPLICATION_FAILOVER_FAILED;
 593         s->error = -EIO;
 594     }
 595 }
 596
 597 static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
 598 {
 599     BlockDriverState *bs = rs->opaque;
 600     BDRVReplicationState *s;
 601     AioContext *aio_context;
 602
 603     aio_context = bdrv_get_aio_context(bs);
 604     aio_context_acquire(aio_context);
 605     s = bs->opaque;
 606
 607     if (s->replication_state != BLOCK_REPLICATION_RUNNING) {
 608         error_setg(errp, "Block replication is not running");
 609         aio_context_release(aio_context);
 610         return;
 611     }
 612
 613     switch (s->mode) {
 614     case REPLICATION_MODE_PRIMARY:
 615         s->replication_state = BLOCK_REPLICATION_DONE;
 616         s->error = 0;
 617         break;
 618     case REPLICATION_MODE_SECONDARY:
 619         /*
 620          * This BDS will be closed, and the job should be completed
 621          * before the BDS is closed, because we will access hidden
 622          * disk, secondary disk in backup_job_completed().
 623          */
 624         if (s->secondary_disk->bs->job) {
 625             block_job_cancel_sync(s->secondary_disk->bs->job);
 626         }
 627
 628         if (!failover) {
 629             secondary_do_checkpoint(s, errp);
 630             s->replication_state = BLOCK_REPLICATION_DONE;
 631             aio_context_release(aio_context);
 632             return;
 633         }
 634
 635         s->replication_state = BLOCK_REPLICATION_FAILOVER;
 636         commit_active_start("replication-commit", s->active_disk->bs,
 637                             s->secondary_disk->bs, 0, BLOCKDEV_ON_ERROR_REPORT,
 638                             replication_done,
 639                             bs, errp, true);
 640         break;
 641     default:
 642         aio_context_release(aio_context);
 643         abort();
 644     }
 645     aio_context_release(aio_context);
 646 }
 647
 648 BlockDriver bdrv_replication = {
 649     .format_name                = "replication",
 650     .protocol_name              = "replication",
 651     .instance_size              = sizeof(BDRVReplicationState),
 652
 653     .bdrv_open                  = replication_open,
 654     .bdrv_close                 = replication_close,
 655
 656     .bdrv_getlength             = replication_getlength,
 657     .bdrv_co_readv              = replication_co_readv,
 658     .bdrv_co_writev             = replication_co_writev,
 659
 660     .is_filter                  = true,
 661     .bdrv_recurse_is_first_non_filter = replication_recurse_is_first_non_filter,
 662
 663     .has_variable_length        = true,
 664 };
 665
 666 static void bdrv_replication_init(void)
 667 {
 668     bdrv_register(&bdrv_replication);
 669 }
 670
 671 block_init(bdrv_replication_init);