qemu/job.c
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   1/*
   2 * Background jobs (long-running operations)
   3 *
   4 * Copyright (c) 2011 IBM Corp.
   5 * Copyright (c) 2012, 2018 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 "qapi/error.h"
  28#include "qemu/job.h"
  29#include "qemu/id.h"
  30#include "qemu/main-loop.h"
  31#include "block/aio-wait.h"
  32#include "trace-root.h"
  33#include "qapi/qapi-events-job.h"
  34
  35static QLIST_HEAD(, Job) jobs = QLIST_HEAD_INITIALIZER(jobs);
  36
  37/* Job State Transition Table */
  38bool JobSTT[JOB_STATUS__MAX][JOB_STATUS__MAX] = {
  39                                    /* U, C, R, P, Y, S, W, D, X, E, N */
  40    /* U: */ [JOB_STATUS_UNDEFINED] = {0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0},
  41    /* C: */ [JOB_STATUS_CREATED]   = {0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1},
  42    /* R: */ [JOB_STATUS_RUNNING]   = {0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0},
  43    /* P: */ [JOB_STATUS_PAUSED]    = {0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0},
  44    /* Y: */ [JOB_STATUS_READY]     = {0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0},
  45    /* S: */ [JOB_STATUS_STANDBY]   = {0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0},
  46    /* W: */ [JOB_STATUS_WAITING]   = {0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0},
  47    /* D: */ [JOB_STATUS_PENDING]   = {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0},
  48    /* X: */ [JOB_STATUS_ABORTING]  = {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0},
  49    /* E: */ [JOB_STATUS_CONCLUDED] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1},
  50    /* N: */ [JOB_STATUS_NULL]      = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
  51};
  52
  53bool JobVerbTable[JOB_VERB__MAX][JOB_STATUS__MAX] = {
  54                                    /* U, C, R, P, Y, S, W, D, X, E, N */
  55    [JOB_VERB_CANCEL]               = {0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0},
  56    [JOB_VERB_PAUSE]                = {0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0},
  57    [JOB_VERB_RESUME]               = {0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0},
  58    [JOB_VERB_SET_SPEED]            = {0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0},
  59    [JOB_VERB_COMPLETE]             = {0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0},
  60    [JOB_VERB_FINALIZE]             = {0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0},
  61    [JOB_VERB_DISMISS]              = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0},
  62};
  63
  64/* Transactional group of jobs */
  65struct JobTxn {
  66
  67    /* Is this txn being cancelled? */
  68    bool aborting;
  69
  70    /* List of jobs */
  71    QLIST_HEAD(, Job) jobs;
  72
  73    /* Reference count */
  74    int refcnt;
  75};
  76
  77/* Right now, this mutex is only needed to synchronize accesses to job->busy
  78 * and job->sleep_timer, such as concurrent calls to job_do_yield and
  79 * job_enter. */
  80static QemuMutex job_mutex;
  81
  82static void job_lock(void)
  83{
  84    qemu_mutex_lock(&job_mutex);
  85}
  86
  87static void job_unlock(void)
  88{
  89    qemu_mutex_unlock(&job_mutex);
  90}
  91
  92static void __attribute__((__constructor__)) job_init(void)
  93{
  94    qemu_mutex_init(&job_mutex);
  95}
  96
  97JobTxn *job_txn_new(void)
  98{
  99    JobTxn *txn = g_new0(JobTxn, 1);
 100    QLIST_INIT(&txn->jobs);
 101    txn->refcnt = 1;
 102    return txn;
 103}
 104
 105static void job_txn_ref(JobTxn *txn)
 106{
 107    txn->refcnt++;
 108}
 109
 110void job_txn_unref(JobTxn *txn)
 111{
 112    if (txn && --txn->refcnt == 0) {
 113        g_free(txn);
 114    }
 115}
 116
 117void job_txn_add_job(JobTxn *txn, Job *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    job_txn_ref(txn);
 128}
 129
 130static void job_txn_del_job(Job *job)
 131{
 132    if (job->txn) {
 133        QLIST_REMOVE(job, txn_list);
 134        job_txn_unref(job->txn);
 135        job->txn = NULL;
 136    }
 137}
 138
 139static int job_txn_apply(JobTxn *txn, int fn(Job *))
 140{
 141    Job *job, *next;
 142    int rc = 0;
 143
 144    QLIST_FOREACH_SAFE(job, &txn->jobs, txn_list, next) {
 145        rc = fn(job);
 146        if (rc) {
 147            break;
 148        }
 149    }
 150    return rc;
 151}
 152
 153bool job_is_internal(Job *job)
 154{
 155    return (job->id == NULL);
 156}
 157
 158static void job_state_transition(Job *job, JobStatus s1)
 159{
 160    JobStatus s0 = job->status;
 161    assert(s1 >= 0 && s1 < JOB_STATUS__MAX);
 162    trace_job_state_transition(job, job->ret,
 163                               JobSTT[s0][s1] ? "allowed" : "disallowed",
 164                               JobStatus_str(s0), JobStatus_str(s1));
 165    assert(JobSTT[s0][s1]);
 166    job->status = s1;
 167
 168    if (!job_is_internal(job) && s1 != s0) {
 169        qapi_event_send_job_status_change(job->id, job->status);
 170    }
 171}
 172
 173int job_apply_verb(Job *job, JobVerb verb, Error **errp)
 174{
 175    JobStatus s0 = job->status;
 176    assert(verb >= 0 && verb < JOB_VERB__MAX);
 177    trace_job_apply_verb(job, JobStatus_str(s0), JobVerb_str(verb),
 178                         JobVerbTable[verb][s0] ? "allowed" : "prohibited");
 179    if (JobVerbTable[verb][s0]) {
 180        return 0;
 181    }
 182    error_setg(errp, "Job '%s' in state '%s' cannot accept command verb '%s'",
 183               job->id, JobStatus_str(s0), JobVerb_str(verb));
 184    return -EPERM;
 185}
 186
 187JobType job_type(const Job *job)
 188{
 189    return job->driver->job_type;
 190}
 191
 192const char *job_type_str(const Job *job)
 193{
 194    return JobType_str(job_type(job));
 195}
 196
 197bool job_is_cancelled(Job *job)
 198{
 199    return job->cancelled;
 200}
 201
 202bool job_is_ready(Job *job)
 203{
 204    switch (job->status) {
 205    case JOB_STATUS_UNDEFINED:
 206    case JOB_STATUS_CREATED:
 207    case JOB_STATUS_RUNNING:
 208    case JOB_STATUS_PAUSED:
 209    case JOB_STATUS_WAITING:
 210    case JOB_STATUS_PENDING:
 211    case JOB_STATUS_ABORTING:
 212    case JOB_STATUS_CONCLUDED:
 213    case JOB_STATUS_NULL:
 214        return false;
 215    case JOB_STATUS_READY:
 216    case JOB_STATUS_STANDBY:
 217        return true;
 218    default:
 219        g_assert_not_reached();
 220    }
 221    return false;
 222}
 223
 224bool job_is_completed(Job *job)
 225{
 226    switch (job->status) {
 227    case JOB_STATUS_UNDEFINED:
 228    case JOB_STATUS_CREATED:
 229    case JOB_STATUS_RUNNING:
 230    case JOB_STATUS_PAUSED:
 231    case JOB_STATUS_READY:
 232    case JOB_STATUS_STANDBY:
 233        return false;
 234    case JOB_STATUS_WAITING:
 235    case JOB_STATUS_PENDING:
 236    case JOB_STATUS_ABORTING:
 237    case JOB_STATUS_CONCLUDED:
 238    case JOB_STATUS_NULL:
 239        return true;
 240    default:
 241        g_assert_not_reached();
 242    }
 243    return false;
 244}
 245
 246static bool job_started(Job *job)
 247{
 248    return job->co;
 249}
 250
 251static bool job_should_pause(Job *job)
 252{
 253    return job->pause_count > 0;
 254}
 255
 256Job *job_next(Job *job)
 257{
 258    if (!job) {
 259        return QLIST_FIRST(&jobs);
 260    }
 261    return QLIST_NEXT(job, job_list);
 262}
 263
 264Job *job_get(const char *id)
 265{
 266    Job *job;
 267
 268    QLIST_FOREACH(job, &jobs, job_list) {
 269        if (job->id && !strcmp(id, job->id)) {
 270            return job;
 271        }
 272    }
 273
 274    return NULL;
 275}
 276
 277static void job_sleep_timer_cb(void *opaque)
 278{
 279    Job *job = opaque;
 280
 281    job_enter(job);
 282}
 283
 284void *job_create(const char *job_id, const JobDriver *driver, JobTxn *txn,
 285                 AioContext *ctx, int flags, BlockCompletionFunc *cb,
 286                 void *opaque, Error **errp)
 287{
 288    Job *job;
 289
 290    if (job_id) {
 291        if (flags & JOB_INTERNAL) {
 292            error_setg(errp, "Cannot specify job ID for internal job");
 293            return NULL;
 294        }
 295        if (!id_wellformed(job_id)) {
 296            error_setg(errp, "Invalid job ID '%s'", job_id);
 297            return NULL;
 298        }
 299        if (job_get(job_id)) {
 300            error_setg(errp, "Job ID '%s' already in use", job_id);
 301            return NULL;
 302        }
 303    } else if (!(flags & JOB_INTERNAL)) {
 304        error_setg(errp, "An explicit job ID is required");
 305        return NULL;
 306    }
 307
 308    job = g_malloc0(driver->instance_size);
 309    job->driver        = driver;
 310    job->id            = g_strdup(job_id);
 311    job->refcnt        = 1;
 312    job->aio_context   = ctx;
 313    job->busy          = false;
 314    job->paused        = true;
 315    job->pause_count   = 1;
 316    job->auto_finalize = !(flags & JOB_MANUAL_FINALIZE);
 317    job->auto_dismiss  = !(flags & JOB_MANUAL_DISMISS);
 318    job->cb            = cb;
 319    job->opaque        = opaque;
 320
 321    notifier_list_init(&job->on_finalize_cancelled);
 322    notifier_list_init(&job->on_finalize_completed);
 323    notifier_list_init(&job->on_pending);
 324    notifier_list_init(&job->on_ready);
 325
 326    job_state_transition(job, JOB_STATUS_CREATED);
 327    aio_timer_init(qemu_get_aio_context(), &job->sleep_timer,
 328                   QEMU_CLOCK_REALTIME, SCALE_NS,
 329                   job_sleep_timer_cb, job);
 330
 331    QLIST_INSERT_HEAD(&jobs, job, job_list);
 332
 333    /* Single jobs are modeled as single-job transactions for sake of
 334     * consolidating the job management logic */
 335    if (!txn) {
 336        txn = job_txn_new();
 337        job_txn_add_job(txn, job);
 338        job_txn_unref(txn);
 339    } else {
 340        job_txn_add_job(txn, job);
 341    }
 342
 343    return job;
 344}
 345
 346void job_ref(Job *job)
 347{
 348    ++job->refcnt;
 349}
 350
 351void job_unref(Job *job)
 352{
 353    if (--job->refcnt == 0) {
 354        assert(job->status == JOB_STATUS_NULL);
 355        assert(!timer_pending(&job->sleep_timer));
 356        assert(!job->txn);
 357
 358        if (job->driver->free) {
 359            job->driver->free(job);
 360        }
 361
 362        QLIST_REMOVE(job, job_list);
 363
 364        error_free(job->err);
 365        g_free(job->id);
 366        g_free(job);
 367    }
 368}
 369
 370void job_progress_update(Job *job, uint64_t done)
 371{
 372    job->progress_current += done;
 373}
 374
 375void job_progress_set_remaining(Job *job, uint64_t remaining)
 376{
 377    job->progress_total = job->progress_current + remaining;
 378}
 379
 380void job_progress_increase_remaining(Job *job, uint64_t delta)
 381{
 382    job->progress_total += delta;
 383}
 384
 385void job_event_cancelled(Job *job)
 386{
 387    notifier_list_notify(&job->on_finalize_cancelled, job);
 388}
 389
 390void job_event_completed(Job *job)
 391{
 392    notifier_list_notify(&job->on_finalize_completed, job);
 393}
 394
 395static void job_event_pending(Job *job)
 396{
 397    notifier_list_notify(&job->on_pending, job);
 398}
 399
 400static void job_event_ready(Job *job)
 401{
 402    notifier_list_notify(&job->on_ready, job);
 403}
 404
 405static void job_event_idle(Job *job)
 406{
 407    notifier_list_notify(&job->on_idle, job);
 408}
 409
 410void job_enter_cond(Job *job, bool(*fn)(Job *job))
 411{
 412    if (!job_started(job)) {
 413        return;
 414    }
 415    if (job->deferred_to_main_loop) {
 416        return;
 417    }
 418
 419    job_lock();
 420    if (job->busy) {
 421        job_unlock();
 422        return;
 423    }
 424
 425    if (fn && !fn(job)) {
 426        job_unlock();
 427        return;
 428    }
 429
 430    assert(!job->deferred_to_main_loop);
 431    timer_del(&job->sleep_timer);
 432    job->busy = true;
 433    job_unlock();
 434    aio_co_enter(job->aio_context, job->co);
 435}
 436
 437void job_enter(Job *job)
 438{
 439    job_enter_cond(job, NULL);
 440}
 441
 442/* Yield, and schedule a timer to reenter the coroutine after @ns nanoseconds.
 443 * Reentering the job coroutine with job_enter() before the timer has expired
 444 * is allowed and cancels the timer.
 445 *
 446 * If @ns is (uint64_t) -1, no timer is scheduled and job_enter() must be
 447 * called explicitly. */
 448static void coroutine_fn job_do_yield(Job *job, uint64_t ns)
 449{
 450    job_lock();
 451    if (ns != -1) {
 452        timer_mod(&job->sleep_timer, ns);
 453    }
 454    job->busy = false;
 455    job_event_idle(job);
 456    job_unlock();
 457    qemu_coroutine_yield();
 458
 459    /* Set by job_enter_cond() before re-entering the coroutine.  */
 460    assert(job->busy);
 461}
 462
 463void coroutine_fn job_pause_point(Job *job)
 464{
 465    assert(job && job_started(job));
 466
 467    if (!job_should_pause(job)) {
 468        return;
 469    }
 470    if (job_is_cancelled(job)) {
 471        return;
 472    }
 473
 474    if (job->driver->pause) {
 475        job->driver->pause(job);
 476    }
 477
 478    if (job_should_pause(job) && !job_is_cancelled(job)) {
 479        JobStatus status = job->status;
 480        job_state_transition(job, status == JOB_STATUS_READY
 481                                  ? JOB_STATUS_STANDBY
 482                                  : JOB_STATUS_PAUSED);
 483        job->paused = true;
 484        job_do_yield(job, -1);
 485        job->paused = false;
 486        job_state_transition(job, status);
 487    }
 488
 489    if (job->driver->resume) {
 490        job->driver->resume(job);
 491    }
 492}
 493
 494void job_yield(Job *job)
 495{
 496    assert(job->busy);
 497
 498    /* Check cancellation *before* setting busy = false, too!  */
 499    if (job_is_cancelled(job)) {
 500        return;
 501    }
 502
 503    if (!job_should_pause(job)) {
 504        job_do_yield(job, -1);
 505    }
 506
 507    job_pause_point(job);
 508}
 509
 510void coroutine_fn job_sleep_ns(Job *job, int64_t ns)
 511{
 512    assert(job->busy);
 513
 514    /* Check cancellation *before* setting busy = false, too!  */
 515    if (job_is_cancelled(job)) {
 516        return;
 517    }
 518
 519    if (!job_should_pause(job)) {
 520        job_do_yield(job, qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + ns);
 521    }
 522
 523    job_pause_point(job);
 524}
 525
 526/* Assumes the block_job_mutex is held */
 527static bool job_timer_not_pending(Job *job)
 528{
 529    return !timer_pending(&job->sleep_timer);
 530}
 531
 532void job_pause(Job *job)
 533{
 534    job->pause_count++;
 535}
 536
 537void job_resume(Job *job)
 538{
 539    assert(job->pause_count > 0);
 540    job->pause_count--;
 541    if (job->pause_count) {
 542        return;
 543    }
 544
 545    /* kick only if no timer is pending */
 546    job_enter_cond(job, job_timer_not_pending);
 547}
 548
 549void job_user_pause(Job *job, Error **errp)
 550{
 551    if (job_apply_verb(job, JOB_VERB_PAUSE, errp)) {
 552        return;
 553    }
 554    if (job->user_paused) {
 555        error_setg(errp, "Job is already paused");
 556        return;
 557    }
 558    job->user_paused = true;
 559    job_pause(job);
 560}
 561
 562bool job_user_paused(Job *job)
 563{
 564    return job->user_paused;
 565}
 566
 567void job_user_resume(Job *job, Error **errp)
 568{
 569    assert(job);
 570    if (!job->user_paused || job->pause_count <= 0) {
 571        error_setg(errp, "Can't resume a job that was not paused");
 572        return;
 573    }
 574    if (job_apply_verb(job, JOB_VERB_RESUME, errp)) {
 575        return;
 576    }
 577    if (job->driver->user_resume) {
 578        job->driver->user_resume(job);
 579    }
 580    job->user_paused = false;
 581    job_resume(job);
 582}
 583
 584static void job_do_dismiss(Job *job)
 585{
 586    assert(job);
 587    job->busy = false;
 588    job->paused = false;
 589    job->deferred_to_main_loop = true;
 590
 591    job_txn_del_job(job);
 592
 593    job_state_transition(job, JOB_STATUS_NULL);
 594    job_unref(job);
 595}
 596
 597void job_dismiss(Job **jobptr, Error **errp)
 598{
 599    Job *job = *jobptr;
 600    /* similarly to _complete, this is QMP-interface only. */
 601    assert(job->id);
 602    if (job_apply_verb(job, JOB_VERB_DISMISS, errp)) {
 603        return;
 604    }
 605
 606    job_do_dismiss(job);
 607    *jobptr = NULL;
 608}
 609
 610void job_early_fail(Job *job)
 611{
 612    assert(job->status == JOB_STATUS_CREATED);
 613    job_do_dismiss(job);
 614}
 615
 616static void job_conclude(Job *job)
 617{
 618    job_state_transition(job, JOB_STATUS_CONCLUDED);
 619    if (job->auto_dismiss || !job_started(job)) {
 620        job_do_dismiss(job);
 621    }
 622}
 623
 624static void job_update_rc(Job *job)
 625{
 626    if (!job->ret && job_is_cancelled(job)) {
 627        job->ret = -ECANCELED;
 628    }
 629    if (job->ret) {
 630        if (!job->err) {
 631            error_setg(&job->err, "%s", strerror(-job->ret));
 632        }
 633        job_state_transition(job, JOB_STATUS_ABORTING);
 634    }
 635}
 636
 637static void job_commit(Job *job)
 638{
 639    assert(!job->ret);
 640    if (job->driver->commit) {
 641        job->driver->commit(job);
 642    }
 643}
 644
 645static void job_abort(Job *job)
 646{
 647    assert(job->ret);
 648    if (job->driver->abort) {
 649        job->driver->abort(job);
 650    }
 651}
 652
 653static void job_clean(Job *job)
 654{
 655    if (job->driver->clean) {
 656        job->driver->clean(job);
 657    }
 658}
 659
 660static int job_finalize_single(Job *job)
 661{
 662    assert(job_is_completed(job));
 663
 664    /* Ensure abort is called for late-transactional failures */
 665    job_update_rc(job);
 666
 667    if (!job->ret) {
 668        job_commit(job);
 669    } else {
 670        job_abort(job);
 671    }
 672    job_clean(job);
 673
 674    if (job->cb) {
 675        job->cb(job->opaque, job->ret);
 676    }
 677
 678    /* Emit events only if we actually started */
 679    if (job_started(job)) {
 680        if (job_is_cancelled(job)) {
 681            job_event_cancelled(job);
 682        } else {
 683            job_event_completed(job);
 684        }
 685    }
 686
 687    job_txn_del_job(job);
 688    job_conclude(job);
 689    return 0;
 690}
 691
 692static void job_cancel_async(Job *job, bool force)
 693{
 694    if (job->user_paused) {
 695        /* Do not call job_enter here, the caller will handle it.  */
 696        if (job->driver->user_resume) {
 697            job->driver->user_resume(job);
 698        }
 699        job->user_paused = false;
 700        assert(job->pause_count > 0);
 701        job->pause_count--;
 702    }
 703    job->cancelled = true;
 704    /* To prevent 'force == false' overriding a previous 'force == true' */
 705    job->force_cancel |= force;
 706}
 707
 708static void job_completed_txn_abort(Job *job)
 709{
 710    AioContext *outer_ctx = job->aio_context;
 711    AioContext *ctx;
 712    JobTxn *txn = job->txn;
 713    Job *other_job;
 714
 715    if (txn->aborting) {
 716        /*
 717         * We are cancelled by another job, which will handle everything.
 718         */
 719        return;
 720    }
 721    txn->aborting = true;
 722    job_txn_ref(txn);
 723
 724    /* We can only hold the single job's AioContext lock while calling
 725     * job_finalize_single() because the finalization callbacks can involve
 726     * calls of AIO_WAIT_WHILE(), which could deadlock otherwise. */
 727    aio_context_release(outer_ctx);
 728
 729    /* Other jobs are effectively cancelled by us, set the status for
 730     * them; this job, however, may or may not be cancelled, depending
 731     * on the caller, so leave it. */
 732    QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 733        if (other_job != job) {
 734            ctx = other_job->aio_context;
 735            aio_context_acquire(ctx);
 736            job_cancel_async(other_job, false);
 737            aio_context_release(ctx);
 738        }
 739    }
 740    while (!QLIST_EMPTY(&txn->jobs)) {
 741        other_job = QLIST_FIRST(&txn->jobs);
 742        ctx = other_job->aio_context;
 743        aio_context_acquire(ctx);
 744        if (!job_is_completed(other_job)) {
 745            assert(job_is_cancelled(other_job));
 746            job_finish_sync(other_job, NULL, NULL);
 747        }
 748        job_finalize_single(other_job);
 749        aio_context_release(ctx);
 750    }
 751
 752    aio_context_acquire(outer_ctx);
 753
 754    job_txn_unref(txn);
 755}
 756
 757static int job_prepare(Job *job)
 758{
 759    if (job->ret == 0 && job->driver->prepare) {
 760        job->ret = job->driver->prepare(job);
 761        job_update_rc(job);
 762    }
 763    return job->ret;
 764}
 765
 766static int job_needs_finalize(Job *job)
 767{
 768    return !job->auto_finalize;
 769}
 770
 771static void job_do_finalize(Job *job)
 772{
 773    int rc;
 774    assert(job && job->txn);
 775
 776    /* prepare the transaction to complete */
 777    rc = job_txn_apply(job->txn, job_prepare);
 778    if (rc) {
 779        job_completed_txn_abort(job);
 780    } else {
 781        job_txn_apply(job->txn, job_finalize_single);
 782    }
 783}
 784
 785void job_finalize(Job *job, Error **errp)
 786{
 787    assert(job && job->id);
 788    if (job_apply_verb(job, JOB_VERB_FINALIZE, errp)) {
 789        return;
 790    }
 791    job_do_finalize(job);
 792}
 793
 794static int job_transition_to_pending(Job *job)
 795{
 796    job_state_transition(job, JOB_STATUS_PENDING);
 797    if (!job->auto_finalize) {
 798        job_event_pending(job);
 799    }
 800    return 0;
 801}
 802
 803void job_transition_to_ready(Job *job)
 804{
 805    job_state_transition(job, JOB_STATUS_READY);
 806    job_event_ready(job);
 807}
 808
 809static void job_completed_txn_success(Job *job)
 810{
 811    JobTxn *txn = job->txn;
 812    Job *other_job;
 813
 814    job_state_transition(job, JOB_STATUS_WAITING);
 815
 816    /*
 817     * Successful completion, see if there are other running jobs in this
 818     * txn.
 819     */
 820    QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 821        if (!job_is_completed(other_job)) {
 822            return;
 823        }
 824        assert(other_job->ret == 0);
 825    }
 826
 827    job_txn_apply(txn, job_transition_to_pending);
 828
 829    /* If no jobs need manual finalization, automatically do so */
 830    if (job_txn_apply(txn, job_needs_finalize) == 0) {
 831        job_do_finalize(job);
 832    }
 833}
 834
 835static void job_completed(Job *job)
 836{
 837    assert(job && job->txn && !job_is_completed(job));
 838
 839    job_update_rc(job);
 840    trace_job_completed(job, job->ret);
 841    if (job->ret) {
 842        job_completed_txn_abort(job);
 843    } else {
 844        job_completed_txn_success(job);
 845    }
 846}
 847
 848/** Useful only as a type shim for aio_bh_schedule_oneshot. */
 849static void job_exit(void *opaque)
 850{
 851    Job *job = (Job *)opaque;
 852    AioContext *ctx = job->aio_context;
 853
 854    aio_context_acquire(ctx);
 855
 856    /* This is a lie, we're not quiescent, but still doing the completion
 857     * callbacks. However, completion callbacks tend to involve operations that
 858     * drain block nodes, and if .drained_poll still returned true, we would
 859     * deadlock. */
 860    job->busy = false;
 861    job_event_idle(job);
 862
 863    job_completed(job);
 864
 865    aio_context_release(ctx);
 866}
 867
 868/**
 869 * All jobs must allow a pause point before entering their job proper. This
 870 * ensures that jobs can be paused prior to being started, then resumed later.
 871 */
 872static void coroutine_fn job_co_entry(void *opaque)
 873{
 874    Job *job = opaque;
 875
 876    assert(job && job->driver && job->driver->run);
 877    job_pause_point(job);
 878    job->ret = job->driver->run(job, &job->err);
 879    job->deferred_to_main_loop = true;
 880    job->busy = true;
 881    aio_bh_schedule_oneshot(qemu_get_aio_context(), job_exit, job);
 882}
 883
 884void job_start(Job *job)
 885{
 886    assert(job && !job_started(job) && job->paused &&
 887           job->driver && job->driver->run);
 888    job->co = qemu_coroutine_create(job_co_entry, job);
 889    job->pause_count--;
 890    job->busy = true;
 891    job->paused = false;
 892    job_state_transition(job, JOB_STATUS_RUNNING);
 893    aio_co_enter(job->aio_context, job->co);
 894}
 895
 896void job_cancel(Job *job, bool force)
 897{
 898    if (job->status == JOB_STATUS_CONCLUDED) {
 899        job_do_dismiss(job);
 900        return;
 901    }
 902    job_cancel_async(job, force);
 903    if (!job_started(job)) {
 904        job_completed(job);
 905    } else if (job->deferred_to_main_loop) {
 906        job_completed_txn_abort(job);
 907    } else {
 908        job_enter(job);
 909    }
 910}
 911
 912void job_user_cancel(Job *job, bool force, Error **errp)
 913{
 914    if (job_apply_verb(job, JOB_VERB_CANCEL, errp)) {
 915        return;
 916    }
 917    job_cancel(job, force);
 918}
 919
 920/* A wrapper around job_cancel() taking an Error ** parameter so it may be
 921 * used with job_finish_sync() without the need for (rather nasty) function
 922 * pointer casts there. */
 923static void job_cancel_err(Job *job, Error **errp)
 924{
 925    job_cancel(job, false);
 926}
 927
 928int job_cancel_sync(Job *job)
 929{
 930    return job_finish_sync(job, &job_cancel_err, NULL);
 931}
 932
 933void job_cancel_sync_all(void)
 934{
 935    Job *job;
 936    AioContext *aio_context;
 937
 938    while ((job = job_next(NULL))) {
 939        aio_context = job->aio_context;
 940        aio_context_acquire(aio_context);
 941        job_cancel_sync(job);
 942        aio_context_release(aio_context);
 943    }
 944}
 945
 946int job_complete_sync(Job *job, Error **errp)
 947{
 948    return job_finish_sync(job, job_complete, errp);
 949}
 950
 951void job_complete(Job *job, Error **errp)
 952{
 953    /* Should not be reachable via external interface for internal jobs */
 954    assert(job->id);
 955    if (job_apply_verb(job, JOB_VERB_COMPLETE, errp)) {
 956        return;
 957    }
 958    if (job->pause_count || job_is_cancelled(job) || !job->driver->complete) {
 959        error_setg(errp, "The active block job '%s' cannot be completed",
 960                   job->id);
 961        return;
 962    }
 963
 964    job->driver->complete(job, errp);
 965}
 966
 967int job_finish_sync(Job *job, void (*finish)(Job *, Error **errp), Error **errp)
 968{
 969    Error *local_err = NULL;
 970    int ret;
 971
 972    job_ref(job);
 973
 974    if (finish) {
 975        finish(job, &local_err);
 976    }
 977    if (local_err) {
 978        error_propagate(errp, local_err);
 979        job_unref(job);
 980        return -EBUSY;
 981    }
 982
 983    AIO_WAIT_WHILE(job->aio_context,
 984                   (job_enter(job), !job_is_completed(job)));
 985
 986    ret = (job_is_cancelled(job) && job->ret == 0) ? -ECANCELED : job->ret;
 987    job_unref(job);
 988    return ret;
 989}
 990