blockjob.c

   1 /*
   2  * QEMU System Emulator block driver
   3  *
   4  * Copyright (c) 2011 IBM Corp.
   5  * Copyright (c) 2012 Red Hat, Inc.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23  * THE SOFTWARE.
  24  */
  25
  26 #include "qemu/osdep.h"
  27 #include "qemu-common.h"
  28 #include "block/block.h"
  29 #include "block/blockjob_int.h"
  30 #include "block/block_int.h"
  31 #include "block/trace.h"
  32 #include "sysemu/block-backend.h"
  33 #include "qapi/error.h"
  34 #include "qapi/qapi-events-block-core.h"
  35 #include "qapi/qmp/qerror.h"
  36 #include "qemu/coroutine.h"
  37 #include "qemu/timer.h"
  38
  39 /* Transactional group of block jobs */
  40 struct BlockJobTxn {
  41
  42     /* Is this txn being cancelled? */
  43     bool aborting;
  44
  45     /* List of jobs */
  46     QLIST_HEAD(, BlockJob) jobs;
  47
  48     /* Reference count */
  49     int refcnt;
  50 };
  51
  52 /*
  53  * The block job API is composed of two categories of functions.
  54  *
  55  * The first includes functions used by the monitor.  The monitor is
  56  * peculiar in that it accesses the block job list with block_job_get, and
  57  * therefore needs consistency across block_job_get and the actual operation
  58  * (e.g. block_job_set_speed).  The consistency is achieved with
  59  * aio_context_acquire/release.  These functions are declared in blockjob.h.
  60  *
  61  * The second includes functions used by the block job drivers and sometimes
  62  * by the core block layer.  These do not care about locking, because the
  63  * whole coroutine runs under the AioContext lock, and are declared in
  64  * blockjob_int.h.
  65  */
  66
  67 static bool is_block_job(Job *job)
  68 {
  69     return job_type(job) == JOB_TYPE_BACKUP ||
  70            job_type(job) == JOB_TYPE_COMMIT ||
  71            job_type(job) == JOB_TYPE_MIRROR ||
  72            job_type(job) == JOB_TYPE_STREAM;
  73 }
  74
  75 BlockJob *block_job_next(BlockJob *bjob)
  76 {
  77     Job *job = bjob ? &bjob->job : NULL;
  78
  79     do {
  80         job = job_next(job);
  81     } while (job && !is_block_job(job));
  82
  83     return job ? container_of(job, BlockJob, job) : NULL;
  84 }
  85
  86 BlockJob *block_job_get(const char *id)
  87 {
  88     Job *job = job_get(id);
  89
  90     if (job && is_block_job(job)) {
  91         return container_of(job, BlockJob, job);
  92     } else {
  93         return NULL;
  94     }
  95 }
  96
  97 BlockJobTxn *block_job_txn_new(void)
  98 {
  99     BlockJobTxn *txn = g_new0(BlockJobTxn, 1);
 100     QLIST_INIT(&txn->jobs);
 101     txn->refcnt = 1;
 102     return txn;
 103 }
 104
 105 static void block_job_txn_ref(BlockJobTxn *txn)
 106 {
 107     txn->refcnt++;
 108 }
 109
 110 void block_job_txn_unref(BlockJobTxn *txn)
 111 {
 112     if (txn && --txn->refcnt == 0) {
 113         g_free(txn);
 114     }
 115 }
 116
 117 void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job)
 118 {
 119     if (!txn) {
 120         return;
 121     }
 122
 123     assert(!job->txn);
 124     job->txn = txn;
 125
 126     QLIST_INSERT_HEAD(&txn->jobs, job, txn_list);
 127     block_job_txn_ref(txn);
 128 }
 129
 130 void block_job_txn_del_job(BlockJob *job)
 131 {
 132     if (job->txn) {
 133         QLIST_REMOVE(job, txn_list);
 134         block_job_txn_unref(job->txn);
 135         job->txn = NULL;
 136     }
 137 }
 138
 139 static void block_job_attached_aio_context(AioContext *new_context,
 140                                            void *opaque);
 141 static void block_job_detach_aio_context(void *opaque);
 142
 143 void block_job_free(Job *job)
 144 {
 145     BlockJob *bjob = container_of(job, BlockJob, job);
 146     BlockDriverState *bs = blk_bs(bjob->blk);
 147
 148     assert(!bjob->txn);
 149
 150     bs->job = NULL;
 151     block_job_remove_all_bdrv(bjob);
 152     blk_remove_aio_context_notifier(bjob->blk,
 153                                     block_job_attached_aio_context,
 154                                     block_job_detach_aio_context, bjob);
 155     blk_unref(bjob->blk);
 156     error_free(bjob->blocker);
 157 }
 158
 159 static void block_job_attached_aio_context(AioContext *new_context,
 160                                            void *opaque)
 161 {
 162     BlockJob *job = opaque;
 163
 164     job->job.aio_context = new_context;
 165     if (job->driver->attached_aio_context) {
 166         job->driver->attached_aio_context(job, new_context);
 167     }
 168
 169     job_resume(&job->job);
 170 }
 171
 172 static void block_job_drain(BlockJob *job)
 173 {
 174     /* If job is !job->job.busy this kicks it into the next pause point. */
 175     block_job_enter(job);
 176
 177     blk_drain(job->blk);
 178     if (job->driver->drain) {
 179         job->driver->drain(job);
 180     }
 181 }
 182
 183 static void block_job_detach_aio_context(void *opaque)
 184 {
 185     BlockJob *job = opaque;
 186
 187     /* In case the job terminates during aio_poll()... */
 188     job_ref(&job->job);
 189
 190     job_pause(&job->job);
 191
 192     while (!job->job.paused && !job_is_completed(&job->job)) {
 193         block_job_drain(job);
 194     }
 195
 196     job->job.aio_context = NULL;
 197     job_unref(&job->job);
 198 }
 199
 200 static char *child_job_get_parent_desc(BdrvChild *c)
 201 {
 202     BlockJob *job = c->opaque;
 203     return g_strdup_printf("%s job '%s'", job_type_str(&job->job), job->job.id);
 204 }
 205
 206 static void child_job_drained_begin(BdrvChild *c)
 207 {
 208     BlockJob *job = c->opaque;
 209     job_pause(&job->job);
 210 }
 211
 212 static void child_job_drained_end(BdrvChild *c)
 213 {
 214     BlockJob *job = c->opaque;
 215     job_resume(&job->job);
 216 }
 217
 218 static const BdrvChildRole child_job = {
 219     .get_parent_desc    = child_job_get_parent_desc,
 220     .drained_begin      = child_job_drained_begin,
 221     .drained_end        = child_job_drained_end,
 222     .stay_at_node       = true,
 223 };
 224
 225 void block_job_remove_all_bdrv(BlockJob *job)
 226 {
 227     GSList *l;
 228     for (l = job->nodes; l; l = l->next) {
 229         BdrvChild *c = l->data;
 230         bdrv_op_unblock_all(c->bs, job->blocker);
 231         bdrv_root_unref_child(c);
 232     }
 233     g_slist_free(job->nodes);
 234     job->nodes = NULL;
 235 }
 236
 237 int block_job_add_bdrv(BlockJob *job, const char *name, BlockDriverState *bs,
 238                        uint64_t perm, uint64_t shared_perm, Error **errp)
 239 {
 240     BdrvChild *c;
 241
 242     c = bdrv_root_attach_child(bs, name, &child_job, perm, shared_perm,
 243                                job, errp);
 244     if (c == NULL) {
 245         return -EPERM;
 246     }
 247
 248     job->nodes = g_slist_prepend(job->nodes, c);
 249     bdrv_ref(bs);
 250     bdrv_op_block_all(bs, job->blocker);
 251
 252     return 0;
 253 }
 254
 255 bool block_job_is_internal(BlockJob *job)
 256 {
 257     return (job->job.id == NULL);
 258 }
 259
 260 const BlockJobDriver *block_job_driver(BlockJob *job)
 261 {
 262     return job->driver;
 263 }
 264
 265 static int block_job_prepare(BlockJob *job)
 266 {
 267     if (job->job.ret == 0 && job->driver->prepare) {
 268         job->job.ret = job->driver->prepare(job);
 269     }
 270     return job->job.ret;
 271 }
 272
 273 static void job_cancel_async(Job *job, bool force)
 274 {
 275     if (job->user_paused) {
 276         /* Do not call job_enter here, the caller will handle it.  */
 277         job->user_paused = false;
 278         if (job->driver->user_resume) {
 279             job->driver->user_resume(job);
 280         }
 281         assert(job->pause_count > 0);
 282         job->pause_count--;
 283     }
 284     job->cancelled = true;
 285     /* To prevent 'force == false' overriding a previous 'force == true' */
 286     job->force_cancel |= force;
 287 }
 288
 289 static int block_job_txn_apply(BlockJobTxn *txn, int fn(BlockJob *), bool lock)
 290 {
 291     AioContext *ctx;
 292     BlockJob *job, *next;
 293     int rc = 0;
 294
 295     QLIST_FOREACH_SAFE(job, &txn->jobs, txn_list, next) {
 296         if (lock) {
 297             ctx = blk_get_aio_context(job->blk);
 298             aio_context_acquire(ctx);
 299         }
 300         rc = fn(job);
 301         if (lock) {
 302             aio_context_release(ctx);
 303         }
 304         if (rc) {
 305             break;
 306         }
 307     }
 308     return rc;
 309 }
 310
 311 static int block_job_finish_sync(BlockJob *job,
 312                                  void (*finish)(BlockJob *, Error **errp),
 313                                  Error **errp)
 314 {
 315     Error *local_err = NULL;
 316     int ret;
 317
 318     assert(blk_bs(job->blk)->job == job);
 319
 320     job_ref(&job->job);
 321
 322     if (finish) {
 323         finish(job, &local_err);
 324     }
 325     if (local_err) {
 326         error_propagate(errp, local_err);
 327         job_unref(&job->job);
 328         return -EBUSY;
 329     }
 330     /* block_job_drain calls block_job_enter, and it should be enough to
 331      * induce progress until the job completes or moves to the main thread.
 332     */
 333     while (!job->job.deferred_to_main_loop && !job_is_completed(&job->job)) {
 334         block_job_drain(job);
 335     }
 336     while (!job_is_completed(&job->job)) {
 337         aio_poll(qemu_get_aio_context(), true);
 338     }
 339     ret = (job_is_cancelled(&job->job) && job->job.ret == 0)
 340           ? -ECANCELED : job->job.ret;
 341     job_unref(&job->job);
 342     return ret;
 343 }
 344
 345 static void block_job_completed_txn_abort(BlockJob *job)
 346 {
 347     AioContext *ctx;
 348     BlockJobTxn *txn = job->txn;
 349     BlockJob *other_job;
 350
 351     if (txn->aborting) {
 352         /*
 353          * We are cancelled by another job, which will handle everything.
 354          */
 355         return;
 356     }
 357     txn->aborting = true;
 358     block_job_txn_ref(txn);
 359
 360     /* We are the first failed job. Cancel other jobs. */
 361     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 362         ctx = blk_get_aio_context(other_job->blk);
 363         aio_context_acquire(ctx);
 364     }
 365
 366     /* Other jobs are effectively cancelled by us, set the status for
 367      * them; this job, however, may or may not be cancelled, depending
 368      * on the caller, so leave it. */
 369     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 370         if (other_job != job) {
 371             job_cancel_async(&other_job->job, false);
 372         }
 373     }
 374     while (!QLIST_EMPTY(&txn->jobs)) {
 375         other_job = QLIST_FIRST(&txn->jobs);
 376         ctx = blk_get_aio_context(other_job->blk);
 377         if (!job_is_completed(&other_job->job)) {
 378             assert(job_is_cancelled(&other_job->job));
 379             block_job_finish_sync(other_job, NULL, NULL);
 380         }
 381         job_finalize_single(&other_job->job);
 382         aio_context_release(ctx);
 383     }
 384
 385     block_job_txn_unref(txn);
 386 }
 387
 388 static int block_job_needs_finalize(BlockJob *job)
 389 {
 390     return !job->job.auto_finalize;
 391 }
 392
 393 static int block_job_finalize_single(BlockJob *job)
 394 {
 395     return job_finalize_single(&job->job);
 396 }
 397
 398 static void block_job_do_finalize(BlockJob *job)
 399 {
 400     int rc;
 401     assert(job && job->txn);
 402
 403     /* prepare the transaction to complete */
 404     rc = block_job_txn_apply(job->txn, block_job_prepare, true);
 405     if (rc) {
 406         block_job_completed_txn_abort(job);
 407     } else {
 408         block_job_txn_apply(job->txn, block_job_finalize_single, true);
 409     }
 410 }
 411
 412 static int block_job_transition_to_pending(BlockJob *job)
 413 {
 414     job_state_transition(&job->job, JOB_STATUS_PENDING);
 415     if (!job->job.auto_finalize) {
 416         job_event_pending(&job->job);
 417     }
 418     return 0;
 419 }
 420
 421 static void block_job_completed_txn_success(BlockJob *job)
 422 {
 423     BlockJobTxn *txn = job->txn;
 424     BlockJob *other_job;
 425
 426     job_state_transition(&job->job, JOB_STATUS_WAITING);
 427
 428     /*
 429      * Successful completion, see if there are other running jobs in this
 430      * txn.
 431      */
 432     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 433         if (!job_is_completed(&other_job->job)) {
 434             return;
 435         }
 436         assert(other_job->job.ret == 0);
 437     }
 438
 439     block_job_txn_apply(txn, block_job_transition_to_pending, false);
 440
 441     /* If no jobs need manual finalization, automatically do so */
 442     if (block_job_txn_apply(txn, block_job_needs_finalize, false) == 0) {
 443         block_job_do_finalize(job);
 444     }
 445 }
 446
 447 /* Assumes the job_mutex is held */
 448 static bool job_timer_pending(Job *job)
 449 {
 450     return timer_pending(&job->sleep_timer);
 451 }
 452
 453 void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp)
 454 {
 455     int64_t old_speed = job->speed;
 456
 457     if (job_apply_verb(&job->job, JOB_VERB_SET_SPEED, errp)) {
 458         return;
 459     }
 460     if (speed < 0) {
 461         error_setg(errp, QERR_INVALID_PARAMETER, "speed");
 462         return;
 463     }
 464
 465     ratelimit_set_speed(&job->limit, speed, BLOCK_JOB_SLICE_TIME);
 466
 467     job->speed = speed;
 468     if (speed && speed <= old_speed) {
 469         return;
 470     }
 471
 472     /* kick only if a timer is pending */
 473     job_enter_cond(&job->job, job_timer_pending);
 474 }
 475
 476 int64_t block_job_ratelimit_get_delay(BlockJob *job, uint64_t n)
 477 {
 478     if (!job->speed) {
 479         return 0;
 480     }
 481
 482     return ratelimit_calculate_delay(&job->limit, n);
 483 }
 484
 485 void block_job_complete(BlockJob *job, Error **errp)
 486 {
 487     /* Should not be reachable via external interface for internal jobs */
 488     assert(job->job.id);
 489     if (job_apply_verb(&job->job, JOB_VERB_COMPLETE, errp)) {
 490         return;
 491     }
 492     if (job->job.pause_count || job_is_cancelled(&job->job) ||
 493         !job->driver->complete)
 494     {
 495         error_setg(errp, "The active block job '%s' cannot be completed",
 496                    job->job.id);
 497         return;
 498     }
 499
 500     job->driver->complete(job, errp);
 501 }
 502
 503 void block_job_finalize(BlockJob *job, Error **errp)
 504 {
 505     assert(job && job->job.id);
 506     if (job_apply_verb(&job->job, JOB_VERB_FINALIZE, errp)) {
 507         return;
 508     }
 509     block_job_do_finalize(job);
 510 }
 511
 512 void block_job_dismiss(BlockJob **jobptr, Error **errp)
 513 {
 514     BlockJob *job = *jobptr;
 515     /* similarly to _complete, this is QMP-interface only. */
 516     assert(job->job.id);
 517     if (job_apply_verb(&job->job, JOB_VERB_DISMISS, errp)) {
 518         return;
 519     }
 520
 521     job_do_dismiss(&job->job);
 522     *jobptr = NULL;
 523 }
 524
 525 void block_job_cancel(BlockJob *job, bool force)
 526 {
 527     if (job->job.status == JOB_STATUS_CONCLUDED) {
 528         job_do_dismiss(&job->job);
 529         return;
 530     }
 531     job_cancel_async(&job->job, force);
 532     if (!job_started(&job->job)) {
 533         block_job_completed(job, -ECANCELED);
 534     } else if (job->job.deferred_to_main_loop) {
 535         block_job_completed_txn_abort(job);
 536     } else {
 537         block_job_enter(job);
 538     }
 539 }
 540
 541 void block_job_user_cancel(BlockJob *job, bool force, Error **errp)
 542 {
 543     if (job_apply_verb(&job->job, JOB_VERB_CANCEL, errp)) {
 544         return;
 545     }
 546     block_job_cancel(job, force);
 547 }
 548
 549 /* A wrapper around block_job_cancel() taking an Error ** parameter so it may be
 550  * used with block_job_finish_sync() without the need for (rather nasty)
 551  * function pointer casts there. */
 552 static void block_job_cancel_err(BlockJob *job, Error **errp)
 553 {
 554     block_job_cancel(job, false);
 555 }
 556
 557 int block_job_cancel_sync(BlockJob *job)
 558 {
 559     return block_job_finish_sync(job, &block_job_cancel_err, NULL);
 560 }
 561
 562 void block_job_cancel_sync_all(void)
 563 {
 564     BlockJob *job;
 565     AioContext *aio_context;
 566
 567     while ((job = block_job_next(NULL))) {
 568         aio_context = blk_get_aio_context(job->blk);
 569         aio_context_acquire(aio_context);
 570         block_job_cancel_sync(job);
 571         aio_context_release(aio_context);
 572     }
 573 }
 574
 575 int block_job_complete_sync(BlockJob *job, Error **errp)
 576 {
 577     return block_job_finish_sync(job, &block_job_complete, errp);
 578 }
 579
 580 void block_job_progress_update(BlockJob *job, uint64_t done)
 581 {
 582     job->offset += done;
 583 }
 584
 585 void block_job_progress_set_remaining(BlockJob *job, uint64_t remaining)
 586 {
 587     job->len = job->offset + remaining;
 588 }
 589
 590 BlockJobInfo *block_job_query(BlockJob *job, Error **errp)
 591 {
 592     BlockJobInfo *info;
 593
 594     if (block_job_is_internal(job)) {
 595         error_setg(errp, "Cannot query QEMU internal jobs");
 596         return NULL;
 597     }
 598     info = g_new0(BlockJobInfo, 1);
 599     info->type      = g_strdup(job_type_str(&job->job));
 600     info->device    = g_strdup(job->job.id);
 601     info->len       = job->len;
 602     info->busy      = atomic_read(&job->job.busy);
 603     info->paused    = job->job.pause_count > 0;
 604     info->offset    = job->offset;
 605     info->speed     = job->speed;
 606     info->io_status = job->iostatus;
 607     info->ready     = job->ready;
 608     info->status    = job->job.status;
 609     info->auto_finalize = job->job.auto_finalize;
 610     info->auto_dismiss  = job->job.auto_dismiss;
 611     info->has_error = job->job.ret != 0;
 612     info->error     = job->job.ret ? g_strdup(strerror(-job->job.ret)) : NULL;
 613     return info;
 614 }
 615
 616 static void block_job_iostatus_set_err(BlockJob *job, int error)
 617 {
 618     if (job->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
 619         job->iostatus = error == ENOSPC ? BLOCK_DEVICE_IO_STATUS_NOSPACE :
 620                                           BLOCK_DEVICE_IO_STATUS_FAILED;
 621     }
 622 }
 623
 624 static void block_job_event_cancelled(Notifier *n, void *opaque)
 625 {
 626     BlockJob *job = opaque;
 627
 628     if (block_job_is_internal(job)) {
 629         return;
 630     }
 631
 632     qapi_event_send_block_job_cancelled(job_type(&job->job),
 633                                         job->job.id,
 634                                         job->len,
 635                                         job->offset,
 636                                         job->speed,
 637                                         &error_abort);
 638 }
 639
 640 static void block_job_event_completed(Notifier *n, void *opaque)
 641 {
 642     BlockJob *job = opaque;
 643     const char *msg = NULL;
 644
 645     if (block_job_is_internal(job)) {
 646         return;
 647     }
 648
 649     if (job->job.ret < 0) {
 650         msg = strerror(-job->job.ret);
 651     }
 652
 653     qapi_event_send_block_job_completed(job_type(&job->job),
 654                                         job->job.id,
 655                                         job->len,
 656                                         job->offset,
 657                                         job->speed,
 658                                         !!msg,
 659                                         msg,
 660                                         &error_abort);
 661 }
 662
 663 static void block_job_event_pending(Notifier *n, void *opaque)
 664 {
 665     BlockJob *job = opaque;
 666
 667     if (block_job_is_internal(job)) {
 668         return;
 669     }
 670
 671     qapi_event_send_block_job_pending(job_type(&job->job),
 672                                       job->job.id,
 673                                       &error_abort);
 674 }
 675
 676 /*
 677  * API for block job drivers and the block layer.  These functions are
 678  * declared in blockjob_int.h.
 679  */
 680
 681 void *block_job_create(const char *job_id, const BlockJobDriver *driver,
 682                        BlockJobTxn *txn, BlockDriverState *bs, uint64_t perm,
 683                        uint64_t shared_perm, int64_t speed, int flags,
 684                        BlockCompletionFunc *cb, void *opaque, Error **errp)
 685 {
 686     BlockBackend *blk;
 687     BlockJob *job;
 688     int ret;
 689
 690     if (bs->job) {
 691         error_setg(errp, QERR_DEVICE_IN_USE, bdrv_get_device_name(bs));
 692         return NULL;
 693     }
 694
 695     if (job_id == NULL && !(flags & JOB_INTERNAL)) {
 696         job_id = bdrv_get_device_name(bs);
 697     }
 698
 699     blk = blk_new(perm, shared_perm);
 700     ret = blk_insert_bs(blk, bs, errp);
 701     if (ret < 0) {
 702         blk_unref(blk);
 703         return NULL;
 704     }
 705
 706     job = job_create(job_id, &driver->job_driver, blk_get_aio_context(blk),
 707                      flags, cb, opaque, errp);
 708     if (job == NULL) {
 709         blk_unref(blk);
 710         return NULL;
 711     }
 712
 713     assert(is_block_job(&job->job));
 714     assert(job->job.driver->free == &block_job_free);
 715     assert(job->job.driver->user_resume == &block_job_user_resume);
 716
 717     job->driver        = driver;
 718     job->blk           = blk;
 719
 720     job->finalize_cancelled_notifier.notify = block_job_event_cancelled;
 721     job->finalize_completed_notifier.notify = block_job_event_completed;
 722     job->pending_notifier.notify = block_job_event_pending;
 723
 724     notifier_list_add(&job->job.on_finalize_cancelled,
 725                       &job->finalize_cancelled_notifier);
 726     notifier_list_add(&job->job.on_finalize_completed,
 727                       &job->finalize_completed_notifier);
 728     notifier_list_add(&job->job.on_pending, &job->pending_notifier);
 729
 730     error_setg(&job->blocker, "block device is in use by block job: %s",
 731                job_type_str(&job->job));
 732     block_job_add_bdrv(job, "main node", bs, 0, BLK_PERM_ALL, &error_abort);
 733     bs->job = job;
 734
 735     bdrv_op_unblock(bs, BLOCK_OP_TYPE_DATAPLANE, job->blocker);
 736
 737     blk_add_aio_context_notifier(blk, block_job_attached_aio_context,
 738                                  block_job_detach_aio_context, job);
 739
 740     /* Only set speed when necessary to avoid NotSupported error */
 741     if (speed != 0) {
 742         Error *local_err = NULL;
 743
 744         block_job_set_speed(job, speed, &local_err);
 745         if (local_err) {
 746             job_early_fail(&job->job);
 747             error_propagate(errp, local_err);
 748             return NULL;
 749         }
 750     }
 751
 752     /* Single jobs are modeled as single-job transactions for sake of
 753      * consolidating the job management logic */
 754     if (!txn) {
 755         txn = block_job_txn_new();
 756         block_job_txn_add_job(txn, job);
 757         block_job_txn_unref(txn);
 758     } else {
 759         block_job_txn_add_job(txn, job);
 760     }
 761
 762     return job;
 763 }
 764
 765 void block_job_completed(BlockJob *job, int ret)
 766 {
 767     assert(job && job->txn && !job_is_completed(&job->job));
 768     assert(blk_bs(job->blk)->job == job);
 769     job->job.ret = ret;
 770     job_update_rc(&job->job);
 771     trace_block_job_completed(job, ret, job->job.ret);
 772     if (job->job.ret) {
 773         block_job_completed_txn_abort(job);
 774     } else {
 775         block_job_completed_txn_success(job);
 776     }
 777 }
 778
 779 void block_job_enter(BlockJob *job)
 780 {
 781     job_enter_cond(&job->job, NULL);
 782 }
 783
 784 void block_job_yield(BlockJob *job)
 785 {
 786     assert(job->job.busy);
 787
 788     /* Check cancellation *before* setting busy = false, too!  */
 789     if (job_is_cancelled(&job->job)) {
 790         return;
 791     }
 792
 793     if (!job_should_pause(&job->job)) {
 794         job_do_yield(&job->job, -1);
 795     }
 796
 797     job_pause_point(&job->job);
 798 }
 799
 800 void block_job_iostatus_reset(BlockJob *job)
 801 {
 802     if (job->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
 803         return;
 804     }
 805     assert(job->job.user_paused && job->job.pause_count > 0);
 806     job->iostatus = BLOCK_DEVICE_IO_STATUS_OK;
 807 }
 808
 809 void block_job_user_resume(Job *job)
 810 {
 811     BlockJob *bjob = container_of(job, BlockJob, job);
 812     block_job_iostatus_reset(bjob);
 813 }
 814
 815 void block_job_event_ready(BlockJob *job)
 816 {
 817     job_state_transition(&job->job, JOB_STATUS_READY);
 818     job->ready = true;
 819
 820     if (block_job_is_internal(job)) {
 821         return;
 822     }
 823
 824     qapi_event_send_block_job_ready(job_type(&job->job),
 825                                     job->job.id,
 826                                     job->len,
 827                                     job->offset,
 828                                     job->speed, &error_abort);
 829 }
 830
 831 BlockErrorAction block_job_error_action(BlockJob *job, BlockdevOnError on_err,
 832                                         int is_read, int error)
 833 {
 834     BlockErrorAction action;
 835
 836     switch (on_err) {
 837     case BLOCKDEV_ON_ERROR_ENOSPC:
 838     case BLOCKDEV_ON_ERROR_AUTO:
 839         action = (error == ENOSPC) ?
 840                  BLOCK_ERROR_ACTION_STOP : BLOCK_ERROR_ACTION_REPORT;
 841         break;
 842     case BLOCKDEV_ON_ERROR_STOP:
 843         action = BLOCK_ERROR_ACTION_STOP;
 844         break;
 845     case BLOCKDEV_ON_ERROR_REPORT:
 846         action = BLOCK_ERROR_ACTION_REPORT;
 847         break;
 848     case BLOCKDEV_ON_ERROR_IGNORE:
 849         action = BLOCK_ERROR_ACTION_IGNORE;
 850         break;
 851     default:
 852         abort();
 853     }
 854     if (!block_job_is_internal(job)) {
 855         qapi_event_send_block_job_error(job->job.id,
 856                                         is_read ? IO_OPERATION_TYPE_READ :
 857                                         IO_OPERATION_TYPE_WRITE,
 858                                         action, &error_abort);
 859     }
 860     if (action == BLOCK_ERROR_ACTION_STOP) {
 861         job_pause(&job->job);
 862         /* make the pause user visible, which will be resumed from QMP. */
 863         job->job.user_paused = true;
 864         block_job_iostatus_set_err(job, error);
 865     }
 866     return action;
 867 }