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     bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
  90                                false, errp);
  91     if (!bs->file) {
  92         return -EINVAL;
  93     }
  94
  95     ret = -EINVAL;
  96     opts = qemu_opts_create(&replication_runtime_opts, NULL, 0, &error_abort);
  97     qemu_opts_absorb_qdict(opts, options, &local_err);
  98     if (local_err) {
  99         goto fail;
 100     }
 101
 102     mode = qemu_opt_get(opts, REPLICATION_MODE);
 103     if (!mode) {
 104         error_setg(&local_err, "Missing the option mode");
 105         goto fail;
 106     }
 107
 108     if (!strcmp(mode, "primary")) {
 109         s->mode = REPLICATION_MODE_PRIMARY;
 110         top_id = qemu_opt_get(opts, REPLICATION_TOP_ID);
 111         if (top_id) {
 112             error_setg(&local_err, "The primary side does not support option top-id");
 113             goto fail;
 114         }
 115     } else if (!strcmp(mode, "secondary")) {
 116         s->mode = REPLICATION_MODE_SECONDARY;
 117         top_id = qemu_opt_get(opts, REPLICATION_TOP_ID);
 118         s->top_id = g_strdup(top_id);
 119         if (!s->top_id) {
 120             error_setg(&local_err, "Missing the option top-id");
 121             goto fail;
 122         }
 123     } else {
 124         error_setg(&local_err,
 125                    "The option mode's value should be primary or secondary");
 126         goto fail;
 127     }
 128
 129     s->rs = replication_new(bs, &replication_ops);
 130
 131     ret = 0;
 132
 133 fail:
 134     qemu_opts_del(opts);
 135     error_propagate(errp, local_err);
 136
 137     return ret;
 138 }
 139
 140 static void replication_close(BlockDriverState *bs)
 141 {
 142     BDRVReplicationState *s = bs->opaque;
 143
 144     if (s->replication_state == BLOCK_REPLICATION_RUNNING) {
 145         replication_stop(s->rs, false, NULL);
 146     }
 147     if (s->replication_state == BLOCK_REPLICATION_FAILOVER) {
 148         block_job_cancel_sync(s->active_disk->bs->job);
 149     }
 150
 151     if (s->mode == REPLICATION_MODE_SECONDARY) {
 152         g_free(s->top_id);
 153     }
 154
 155     replication_remove(s->rs);
 156 }
 157
 158 static int64_t replication_getlength(BlockDriverState *bs)
 159 {
 160     return bdrv_getlength(bs->file->bs);
 161 }
 162
 163 static int replication_get_io_status(BDRVReplicationState *s)
 164 {
 165     switch (s->replication_state) {
 166     case BLOCK_REPLICATION_NONE:
 167         return -EIO;
 168     case BLOCK_REPLICATION_RUNNING:
 169         return 0;
 170     case BLOCK_REPLICATION_FAILOVER:
 171         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
 172     case BLOCK_REPLICATION_FAILOVER_FAILED:
 173         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 1;
 174     case BLOCK_REPLICATION_DONE:
 175         /*
 176          * active commit job completes, and active disk and secondary_disk
 177          * is swapped, so we can operate bs->file directly
 178          */
 179         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
 180     default:
 181         abort();
 182     }
 183 }
 184
 185 static int replication_return_value(BDRVReplicationState *s, int ret)
 186 {
 187     if (s->mode == REPLICATION_MODE_SECONDARY) {
 188         return ret;
 189     }
 190
 191     if (ret < 0) {
 192         s->error = ret;
 193         ret = 0;
 194     }
 195
 196     return ret;
 197 }
 198
 199 static coroutine_fn int replication_co_readv(BlockDriverState *bs,
 200                                              int64_t sector_num,
 201                                              int remaining_sectors,
 202                                              QEMUIOVector *qiov)
 203 {
 204     BDRVReplicationState *s = bs->opaque;
 205     BdrvChild *child = s->secondary_disk;
 206     BlockJob *job = NULL;
 207     CowRequest req;
 208     int ret;
 209
 210     if (s->mode == REPLICATION_MODE_PRIMARY) {
 211         /* We only use it to forward primary write requests */
 212         return -EIO;
 213     }
 214
 215     ret = replication_get_io_status(s);
 216     if (ret < 0) {
 217         return ret;
 218     }
 219
 220     if (child && child->bs) {
 221         job = child->bs->job;
 222     }
 223
 224     if (job) {
 225         backup_wait_for_overlapping_requests(child->bs->job, sector_num,
 226                                              remaining_sectors);
 227         backup_cow_request_begin(&req, child->bs->job, sector_num,
 228                                  remaining_sectors);
 229         ret = bdrv_co_readv(bs->file, sector_num, remaining_sectors,
 230                             qiov);
 231         backup_cow_request_end(&req);
 232         goto out;
 233     }
 234
 235     ret = bdrv_co_readv(bs->file, sector_num, remaining_sectors, qiov);
 236 out:
 237     return replication_return_value(s, ret);
 238 }
 239
 240 static coroutine_fn int replication_co_writev(BlockDriverState *bs,
 241                                               int64_t sector_num,
 242                                               int remaining_sectors,
 243                                               QEMUIOVector *qiov)
 244 {
 245     BDRVReplicationState *s = bs->opaque;
 246     QEMUIOVector hd_qiov;
 247     uint64_t bytes_done = 0;
 248     BdrvChild *top = bs->file;
 249     BdrvChild *base = s->secondary_disk;
 250     BdrvChild *target;
 251     int ret, n;
 252
 253     ret = replication_get_io_status(s);
 254     if (ret < 0) {
 255         goto out;
 256     }
 257
 258     if (ret == 0) {
 259         ret = bdrv_co_writev(top, sector_num,
 260                              remaining_sectors, qiov);
 261         return replication_return_value(s, ret);
 262     }
 263
 264     /*
 265      * Failover failed, only write to active disk if the sectors
 266      * have already been allocated in active disk/hidden disk.
 267      */
 268     qemu_iovec_init(&hd_qiov, qiov->niov);
 269     while (remaining_sectors > 0) {
 270         ret = bdrv_is_allocated_above(top->bs, base->bs, sector_num,
 271                                       remaining_sectors, &n);
 272         if (ret < 0) {
 273             goto out1;
 274         }
 275
 276         qemu_iovec_reset(&hd_qiov);
 277         qemu_iovec_concat(&hd_qiov, qiov, bytes_done, n * BDRV_SECTOR_SIZE);
 278
 279         target = ret ? top : base;
 280         ret = bdrv_co_writev(target, sector_num, n, &hd_qiov);
 281         if (ret < 0) {
 282             goto out1;
 283         }
 284
 285         remaining_sectors -= n;
 286         sector_num += n;
 287         bytes_done += n * BDRV_SECTOR_SIZE;
 288     }
 289
 290 out1:
 291     qemu_iovec_destroy(&hd_qiov);
 292 out:
 293     return ret;
 294 }
 295
 296 static bool replication_recurse_is_first_non_filter(BlockDriverState *bs,
 297                                                     BlockDriverState *candidate)
 298 {
 299     return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
 300 }
 301
 302 static void secondary_do_checkpoint(BDRVReplicationState *s, Error **errp)
 303 {
 304     Error *local_err = NULL;
 305     int ret;
 306
 307     if (!s->secondary_disk->bs->job) {
 308         error_setg(errp, "Backup job was cancelled unexpectedly");
 309         return;
 310     }
 311
 312     backup_do_checkpoint(s->secondary_disk->bs->job, &local_err);
 313     if (local_err) {
 314         error_propagate(errp, local_err);
 315         return;
 316     }
 317
 318     ret = s->active_disk->bs->drv->bdrv_make_empty(s->active_disk->bs);
 319     if (ret < 0) {
 320         error_setg(errp, "Cannot make active disk empty");
 321         return;
 322     }
 323
 324     ret = s->hidden_disk->bs->drv->bdrv_make_empty(s->hidden_disk->bs);
 325     if (ret < 0) {
 326         error_setg(errp, "Cannot make hidden disk empty");
 327         return;
 328     }
 329 }
 330
 331 static void reopen_backing_file(BlockDriverState *bs, bool writable,
 332                                 Error **errp)
 333 {
 334     BDRVReplicationState *s = bs->opaque;
 335     BlockReopenQueue *reopen_queue = NULL;
 336     int orig_hidden_flags, orig_secondary_flags;
 337     int new_hidden_flags, new_secondary_flags;
 338     Error *local_err = NULL;
 339
 340     if (writable) {
 341         orig_hidden_flags = s->orig_hidden_flags =
 342                                 bdrv_get_flags(s->hidden_disk->bs);
 343         new_hidden_flags = (orig_hidden_flags | BDRV_O_RDWR) &
 344                                                     ~BDRV_O_INACTIVE;
 345         orig_secondary_flags = s->orig_secondary_flags =
 346                                 bdrv_get_flags(s->secondary_disk->bs);
 347         new_secondary_flags = (orig_secondary_flags | BDRV_O_RDWR) &
 348                                                      ~BDRV_O_INACTIVE;
 349     } else {
 350         orig_hidden_flags = (s->orig_hidden_flags | BDRV_O_RDWR) &
 351                                                     ~BDRV_O_INACTIVE;
 352         new_hidden_flags = s->orig_hidden_flags;
 353         orig_secondary_flags = (s->orig_secondary_flags | BDRV_O_RDWR) &
 354                                                     ~BDRV_O_INACTIVE;
 355         new_secondary_flags = s->orig_secondary_flags;
 356     }
 357
 358     if (orig_hidden_flags != new_hidden_flags) {
 359         reopen_queue = bdrv_reopen_queue(reopen_queue, s->hidden_disk->bs, NULL,
 360                                          new_hidden_flags);
 361     }
 362
 363     if (!(orig_secondary_flags & BDRV_O_RDWR)) {
 364         reopen_queue = bdrv_reopen_queue(reopen_queue, s->secondary_disk->bs,
 365                                          NULL, new_secondary_flags);
 366     }
 367
 368     if (reopen_queue) {
 369         bdrv_reopen_multiple(bdrv_get_aio_context(bs),
 370                              reopen_queue, &local_err);
 371         error_propagate(errp, local_err);
 372     }
 373 }
 374
 375 static void backup_job_cleanup(BlockDriverState *bs)
 376 {
 377     BDRVReplicationState *s = bs->opaque;
 378     BlockDriverState *top_bs;
 379
 380     top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
 381     if (!top_bs) {
 382         return;
 383     }
 384     bdrv_op_unblock_all(top_bs, s->blocker);
 385     error_free(s->blocker);
 386     reopen_backing_file(bs, false, NULL);
 387 }
 388
 389 static void backup_job_completed(void *opaque, int ret)
 390 {
 391     BlockDriverState *bs = opaque;
 392     BDRVReplicationState *s = bs->opaque;
 393
 394     if (s->replication_state != BLOCK_REPLICATION_FAILOVER) {
 395         /* The backup job is cancelled unexpectedly */
 396         s->error = -EIO;
 397     }
 398
 399     backup_job_cleanup(bs);
 400 }
 401
 402 static bool check_top_bs(BlockDriverState *top_bs, BlockDriverState *bs)
 403 {
 404     BdrvChild *child;
 405
 406     /* The bs itself is the top_bs */
 407     if (top_bs == bs) {
 408         return true;
 409     }
 410
 411     /* Iterate over top_bs's children */
 412     QLIST_FOREACH(child, &top_bs->children, next) {
 413         if (child->bs == bs || check_top_bs(child->bs, bs)) {
 414             return true;
 415         }
 416     }
 417
 418     return false;
 419 }
 420
 421 static void replication_start(ReplicationState *rs, ReplicationMode mode,
 422                               Error **errp)
 423 {
 424     BlockDriverState *bs = rs->opaque;
 425     BDRVReplicationState *s;
 426     BlockDriverState *top_bs;
 427     int64_t active_length, hidden_length, disk_length;
 428     AioContext *aio_context;
 429     Error *local_err = NULL;
 430     BlockJob *job;
 431
 432     aio_context = bdrv_get_aio_context(bs);
 433     aio_context_acquire(aio_context);
 434     s = bs->opaque;
 435
 436     if (s->replication_state != BLOCK_REPLICATION_NONE) {
 437         error_setg(errp, "Block replication is running or done");
 438         aio_context_release(aio_context);
 439         return;
 440     }
 441
 442     if (s->mode != mode) {
 443         error_setg(errp, "The parameter mode's value is invalid, needs %d,"
 444                    " but got %d", s->mode, mode);
 445         aio_context_release(aio_context);
 446         return;
 447     }
 448
 449     switch (s->mode) {
 450     case REPLICATION_MODE_PRIMARY:
 451         break;
 452     case REPLICATION_MODE_SECONDARY:
 453         s->active_disk = bs->file;
 454         if (!s->active_disk || !s->active_disk->bs ||
 455                                     !s->active_disk->bs->backing) {
 456             error_setg(errp, "Active disk doesn't have backing file");
 457             aio_context_release(aio_context);
 458             return;
 459         }
 460
 461         s->hidden_disk = s->active_disk->bs->backing;
 462         if (!s->hidden_disk->bs || !s->hidden_disk->bs->backing) {
 463             error_setg(errp, "Hidden disk doesn't have backing file");
 464             aio_context_release(aio_context);
 465             return;
 466         }
 467
 468         s->secondary_disk = s->hidden_disk->bs->backing;
 469         if (!s->secondary_disk->bs || !bdrv_has_blk(s->secondary_disk->bs)) {
 470             error_setg(errp, "The secondary disk doesn't have block backend");
 471             aio_context_release(aio_context);
 472             return;
 473         }
 474
 475         /* verify the length */
 476         active_length = bdrv_getlength(s->active_disk->bs);
 477         hidden_length = bdrv_getlength(s->hidden_disk->bs);
 478         disk_length = bdrv_getlength(s->secondary_disk->bs);
 479         if (active_length < 0 || hidden_length < 0 || disk_length < 0 ||
 480             active_length != hidden_length || hidden_length != disk_length) {
 481             error_setg(errp, "Active disk, hidden disk, secondary disk's length"
 482                        " are not the same");
 483             aio_context_release(aio_context);
 484             return;
 485         }
 486
 487         if (!s->active_disk->bs->drv->bdrv_make_empty ||
 488             !s->hidden_disk->bs->drv->bdrv_make_empty) {
 489             error_setg(errp,
 490                        "Active disk or hidden disk doesn't support make_empty");
 491             aio_context_release(aio_context);
 492             return;
 493         }
 494
 495         /* reopen the backing file in r/w mode */
 496         reopen_backing_file(bs, true, &local_err);
 497         if (local_err) {
 498             error_propagate(errp, local_err);
 499             aio_context_release(aio_context);
 500             return;
 501         }
 502
 503         /* start backup job now */
 504         error_setg(&s->blocker,
 505                    "Block device is in use by internal backup job");
 506
 507         top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
 508         if (!top_bs || !bdrv_is_root_node(top_bs) ||
 509             !check_top_bs(top_bs, bs)) {
 510             error_setg(errp, "No top_bs or it is invalid");
 511             reopen_backing_file(bs, false, NULL);
 512             aio_context_release(aio_context);
 513             return;
 514         }
 515         bdrv_op_block_all(top_bs, s->blocker);
 516         bdrv_op_unblock(top_bs, BLOCK_OP_TYPE_DATAPLANE, s->blocker);
 517
 518         job = backup_job_create(NULL, s->secondary_disk->bs, s->hidden_disk->bs,
 519                                 0, MIRROR_SYNC_MODE_NONE, NULL, false,
 520                                 BLOCKDEV_ON_ERROR_REPORT,
 521                                 BLOCKDEV_ON_ERROR_REPORT, BLOCK_JOB_INTERNAL,
 522                                 backup_job_completed, bs, NULL, &local_err);
 523         if (local_err) {
 524             error_propagate(errp, local_err);
 525             backup_job_cleanup(bs);
 526             aio_context_release(aio_context);
 527             return;
 528         }
 529         block_job_start(job);
 530         break;
 531     default:
 532         aio_context_release(aio_context);
 533         abort();
 534     }
 535
 536     s->replication_state = BLOCK_REPLICATION_RUNNING;
 537
 538     if (s->mode == REPLICATION_MODE_SECONDARY) {
 539         secondary_do_checkpoint(s, errp);
 540     }
 541
 542     s->error = 0;
 543     aio_context_release(aio_context);
 544 }
 545
 546 static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
 547 {
 548     BlockDriverState *bs = rs->opaque;
 549     BDRVReplicationState *s;
 550     AioContext *aio_context;
 551
 552     aio_context = bdrv_get_aio_context(bs);
 553     aio_context_acquire(aio_context);
 554     s = bs->opaque;
 555
 556     if (s->mode == REPLICATION_MODE_SECONDARY) {
 557         secondary_do_checkpoint(s, errp);
 558     }
 559     aio_context_release(aio_context);
 560 }
 561
 562 static void replication_get_error(ReplicationState *rs, Error **errp)
 563 {
 564     BlockDriverState *bs = rs->opaque;
 565     BDRVReplicationState *s;
 566     AioContext *aio_context;
 567
 568     aio_context = bdrv_get_aio_context(bs);
 569     aio_context_acquire(aio_context);
 570     s = bs->opaque;
 571
 572     if (s->replication_state != BLOCK_REPLICATION_RUNNING) {
 573         error_setg(errp, "Block replication is not running");
 574         aio_context_release(aio_context);
 575         return;
 576     }
 577
 578     if (s->error) {
 579         error_setg(errp, "I/O error occurred");
 580         aio_context_release(aio_context);
 581         return;
 582     }
 583     aio_context_release(aio_context);
 584 }
 585
 586 static void replication_done(void *opaque, int ret)
 587 {
 588     BlockDriverState *bs = opaque;
 589     BDRVReplicationState *s = bs->opaque;
 590
 591     if (ret == 0) {
 592         s->replication_state = BLOCK_REPLICATION_DONE;
 593
 594         /* refresh top bs's filename */
 595         bdrv_refresh_filename(bs);
 596         s->active_disk = NULL;
 597         s->secondary_disk = NULL;
 598         s->hidden_disk = NULL;
 599         s->error = 0;
 600     } else {
 601         s->replication_state = BLOCK_REPLICATION_FAILOVER_FAILED;
 602         s->error = -EIO;
 603     }
 604 }
 605
 606 static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
 607 {
 608     BlockDriverState *bs = rs->opaque;
 609     BDRVReplicationState *s;
 610     AioContext *aio_context;
 611
 612     aio_context = bdrv_get_aio_context(bs);
 613     aio_context_acquire(aio_context);
 614     s = bs->opaque;
 615
 616     if (s->replication_state != BLOCK_REPLICATION_RUNNING) {
 617         error_setg(errp, "Block replication is not running");
 618         aio_context_release(aio_context);
 619         return;
 620     }
 621
 622     switch (s->mode) {
 623     case REPLICATION_MODE_PRIMARY:
 624         s->replication_state = BLOCK_REPLICATION_DONE;
 625         s->error = 0;
 626         break;
 627     case REPLICATION_MODE_SECONDARY:
 628         /*
 629          * This BDS will be closed, and the job should be completed
 630          * before the BDS is closed, because we will access hidden
 631          * disk, secondary disk in backup_job_completed().
 632          */
 633         if (s->secondary_disk->bs->job) {
 634             block_job_cancel_sync(s->secondary_disk->bs->job);
 635         }
 636
 637         if (!failover) {
 638             secondary_do_checkpoint(s, errp);
 639             s->replication_state = BLOCK_REPLICATION_DONE;
 640             aio_context_release(aio_context);
 641             return;
 642         }
 643
 644         s->replication_state = BLOCK_REPLICATION_FAILOVER;
 645         commit_active_start(NULL, s->active_disk->bs, s->secondary_disk->bs,
 646                             BLOCK_JOB_INTERNAL, 0, BLOCKDEV_ON_ERROR_REPORT,
 647                             NULL, replication_done, bs, errp, true);
 648         break;
 649     default:
 650         aio_context_release(aio_context);
 651         abort();
 652     }
 653     aio_context_release(aio_context);
 654 }
 655
 656 BlockDriver bdrv_replication = {
 657     .format_name                = "replication",
 658     .protocol_name              = "replication",
 659     .instance_size              = sizeof(BDRVReplicationState),
 660
 661     .bdrv_open                  = replication_open,
 662     .bdrv_close                 = replication_close,
 663     .bdrv_child_perm            = bdrv_filter_default_perms,
 664
 665     .bdrv_getlength             = replication_getlength,
 666     .bdrv_co_readv              = replication_co_readv,
 667     .bdrv_co_writev             = replication_co_writev,
 668
 669     .is_filter                  = true,
 670     .bdrv_recurse_is_first_non_filter = replication_recurse_is_first_non_filter,
 671
 672     .has_variable_length        = true,
 673 };
 674
 675 static void bdrv_replication_init(void)
 676 {
 677     bdrv_register(&bdrv_replication);
 678 }
 679
 680 block_init(bdrv_replication_init);