job.c

   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
  35 static QLIST_HEAD(, Job) jobs = QLIST_HEAD_INITIALIZER(jobs);
  36
  37 /* Job State Transition Table */
  38 bool 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
  53 bool 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 */
  65 struct 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. */
  80 static QemuMutex job_mutex;
  81
  82 static void job_lock(void)
  83 {
  84     qemu_mutex_lock(&job_mutex);
  85 }
  86
  87 static void job_unlock(void)
  88 {
  89     qemu_mutex_unlock(&job_mutex);
  90 }
  91
  92 static void __attribute__((__constructor__)) job_init(void)
  93 {
  94     qemu_mutex_init(&job_mutex);
  95 }
  96
  97 JobTxn *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
 105 static void job_txn_ref(JobTxn *txn)
 106 {
 107     txn->refcnt++;
 108 }
 109
 110 void job_txn_unref(JobTxn *txn)
 111 {
 112     if (txn && --txn->refcnt == 0) {
 113         g_free(txn);
 114     }
 115 }
 116
 117 void 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
 130 static 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
 139 static 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
 153 bool job_is_internal(Job *job)
 154 {
 155     return (job->id == NULL);
 156 }
 157
 158 static 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
 173 int 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
 187 JobType job_type(const Job *job)
 188 {
 189     return job->driver->job_type;
 190 }
 191
 192 const char *job_type_str(const Job *job)
 193 {
 194     return JobType_str(job_type(job));
 195 }
 196
 197 bool job_is_cancelled(Job *job)
 198 {
 199     return job->cancelled;
 200 }
 201
 202 bool 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
 224 bool 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
 246 static bool job_started(Job *job)
 247 {
 248     return job->co;
 249 }
 250
 251 static bool job_should_pause(Job *job)
 252 {
 253     return job->pause_count > 0;
 254 }
 255
 256 Job *job_next(Job *job)
 257 {
 258     if (!job) {
 259         return QLIST_FIRST(&jobs);
 260     }
 261     return QLIST_NEXT(job, job_list);
 262 }
 263
 264 Job *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
 277 static void job_sleep_timer_cb(void *opaque)
 278 {
 279     Job *job = opaque;
 280
 281     job_enter(job);
 282 }
 283
 284 void *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
 346 void job_ref(Job *job)
 347 {
 348     ++job->refcnt;
 349 }
 350
 351 void 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
 370 void job_progress_update(Job *job, uint64_t done)
 371 {
 372     job->progress_current += done;
 373 }
 374
 375 void job_progress_set_remaining(Job *job, uint64_t remaining)
 376 {
 377     job->progress_total = job->progress_current + remaining;
 378 }
 379
 380 void job_progress_increase_remaining(Job *job, uint64_t delta)
 381 {
 382     job->progress_total += delta;
 383 }
 384
 385 void job_event_cancelled(Job *job)
 386 {
 387     notifier_list_notify(&job->on_finalize_cancelled, job);
 388 }
 389
 390 void job_event_completed(Job *job)
 391 {
 392     notifier_list_notify(&job->on_finalize_completed, job);
 393 }
 394
 395 static void job_event_pending(Job *job)
 396 {
 397     notifier_list_notify(&job->on_pending, job);
 398 }
 399
 400 static void job_event_ready(Job *job)
 401 {
 402     notifier_list_notify(&job->on_ready, job);
 403 }
 404
 405 static void job_event_idle(Job *job)
 406 {
 407     notifier_list_notify(&job->on_idle, job);
 408 }
 409
 410 void 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
 437 void 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. */
 448 static 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
 463 void 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
 494 void 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
 510 void 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 */
 527 static bool job_timer_not_pending(Job *job)
 528 {
 529     return !timer_pending(&job->sleep_timer);
 530 }
 531
 532 void job_pause(Job *job)
 533 {
 534     job->pause_count++;
 535 }
 536
 537 void 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
 549 void 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
 562 bool job_user_paused(Job *job)
 563 {
 564     return job->user_paused;
 565 }
 566
 567 void 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
 584 static 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
 597 void 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
 610 void job_early_fail(Job *job)
 611 {
 612     assert(job->status == JOB_STATUS_CREATED);
 613     job_do_dismiss(job);
 614 }
 615
 616 static 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
 624 static 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
 637 static void job_commit(Job *job)
 638 {
 639     assert(!job->ret);
 640     if (job->driver->commit) {
 641         job->driver->commit(job);
 642     }
 643 }
 644
 645 static void job_abort(Job *job)
 646 {
 647     assert(job->ret);
 648     if (job->driver->abort) {
 649         job->driver->abort(job);
 650     }
 651 }
 652
 653 static void job_clean(Job *job)
 654 {
 655     if (job->driver->clean) {
 656         job->driver->clean(job);
 657     }
 658 }
 659
 660 static 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
 692 static 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
 708 static 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
 757 static 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
 766 static int job_needs_finalize(Job *job)
 767 {
 768     return !job->auto_finalize;
 769 }
 770
 771 static 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
 785 void 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
 794 static 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
 803 void job_transition_to_ready(Job *job)
 804 {
 805     job_state_transition(job, JOB_STATUS_READY);
 806     job_event_ready(job);
 807 }
 808
 809 static 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
 835 static 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. */
 849 static 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  */
 872 static 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
 884 void 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
 896 void 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
 912 void 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. */
 923 static void job_cancel_err(Job *job, Error **errp)
 924 {
 925     job_cancel(job, false);
 926 }
 927
 928 int job_cancel_sync(Job *job)
 929 {
 930     return job_finish_sync(job, &job_cancel_err, NULL);
 931 }
 932
 933 void 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
 946 int job_complete_sync(Job *job, Error **errp)
 947 {
 948     return job_finish_sync(job, job_complete, errp);
 949 }
 950
 951 void 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
 967 int 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 }