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 "qemu-common.h"
  28 #include "qapi/error.h"
  29 #include "qemu/job.h"
  30 #include "qemu/id.h"
  31 #include "qemu/main-loop.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_wake(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 void job_drain(Job *job)
 527 {
 528     /* If job is !busy this kicks it into the next pause point. */
 529     job_enter(job);
 530
 531     if (job->driver->drain) {
 532         job->driver->drain(job);
 533     }
 534 }
 535
 536 /* Assumes the block_job_mutex is held */
 537 static bool job_timer_not_pending(Job *job)
 538 {
 539     return !timer_pending(&job->sleep_timer);
 540 }
 541
 542 void job_pause(Job *job)
 543 {
 544     job->pause_count++;
 545 }
 546
 547 void job_resume(Job *job)
 548 {
 549     assert(job->pause_count > 0);
 550     job->pause_count--;
 551     if (job->pause_count) {
 552         return;
 553     }
 554
 555     /* kick only if no timer is pending */
 556     job_enter_cond(job, job_timer_not_pending);
 557 }
 558
 559 void job_user_pause(Job *job, Error **errp)
 560 {
 561     if (job_apply_verb(job, JOB_VERB_PAUSE, errp)) {
 562         return;
 563     }
 564     if (job->user_paused) {
 565         error_setg(errp, "Job is already paused");
 566         return;
 567     }
 568     job->user_paused = true;
 569     job_pause(job);
 570 }
 571
 572 bool job_user_paused(Job *job)
 573 {
 574     return job->user_paused;
 575 }
 576
 577 void job_user_resume(Job *job, Error **errp)
 578 {
 579     assert(job);
 580     if (!job->user_paused || job->pause_count <= 0) {
 581         error_setg(errp, "Can't resume a job that was not paused");
 582         return;
 583     }
 584     if (job_apply_verb(job, JOB_VERB_RESUME, errp)) {
 585         return;
 586     }
 587     if (job->driver->user_resume) {
 588         job->driver->user_resume(job);
 589     }
 590     job->user_paused = false;
 591     job_resume(job);
 592 }
 593
 594 static void job_do_dismiss(Job *job)
 595 {
 596     assert(job);
 597     job->busy = false;
 598     job->paused = false;
 599     job->deferred_to_main_loop = true;
 600
 601     job_txn_del_job(job);
 602
 603     job_state_transition(job, JOB_STATUS_NULL);
 604     job_unref(job);
 605 }
 606
 607 void job_dismiss(Job **jobptr, Error **errp)
 608 {
 609     Job *job = *jobptr;
 610     /* similarly to _complete, this is QMP-interface only. */
 611     assert(job->id);
 612     if (job_apply_verb(job, JOB_VERB_DISMISS, errp)) {
 613         return;
 614     }
 615
 616     job_do_dismiss(job);
 617     *jobptr = NULL;
 618 }
 619
 620 void job_early_fail(Job *job)
 621 {
 622     assert(job->status == JOB_STATUS_CREATED);
 623     job_do_dismiss(job);
 624 }
 625
 626 static void job_conclude(Job *job)
 627 {
 628     job_state_transition(job, JOB_STATUS_CONCLUDED);
 629     if (job->auto_dismiss || !job_started(job)) {
 630         job_do_dismiss(job);
 631     }
 632 }
 633
 634 static void job_update_rc(Job *job)
 635 {
 636     if (!job->ret && job_is_cancelled(job)) {
 637         job->ret = -ECANCELED;
 638     }
 639     if (job->ret) {
 640         if (!job->err) {
 641             error_setg(&job->err, "%s", strerror(-job->ret));
 642         }
 643         job_state_transition(job, JOB_STATUS_ABORTING);
 644     }
 645 }
 646
 647 static void job_commit(Job *job)
 648 {
 649     assert(!job->ret);
 650     if (job->driver->commit) {
 651         job->driver->commit(job);
 652     }
 653 }
 654
 655 static void job_abort(Job *job)
 656 {
 657     assert(job->ret);
 658     if (job->driver->abort) {
 659         job->driver->abort(job);
 660     }
 661 }
 662
 663 static void job_clean(Job *job)
 664 {
 665     if (job->driver->clean) {
 666         job->driver->clean(job);
 667     }
 668 }
 669
 670 static int job_finalize_single(Job *job)
 671 {
 672     assert(job_is_completed(job));
 673
 674     /* Ensure abort is called for late-transactional failures */
 675     job_update_rc(job);
 676
 677     if (!job->ret) {
 678         job_commit(job);
 679     } else {
 680         job_abort(job);
 681     }
 682     job_clean(job);
 683
 684     if (job->cb) {
 685         job->cb(job->opaque, job->ret);
 686     }
 687
 688     /* Emit events only if we actually started */
 689     if (job_started(job)) {
 690         if (job_is_cancelled(job)) {
 691             job_event_cancelled(job);
 692         } else {
 693             job_event_completed(job);
 694         }
 695     }
 696
 697     job_txn_del_job(job);
 698     job_conclude(job);
 699     return 0;
 700 }
 701
 702 static void job_cancel_async(Job *job, bool force)
 703 {
 704     if (job->user_paused) {
 705         /* Do not call job_enter here, the caller will handle it.  */
 706         if (job->driver->user_resume) {
 707             job->driver->user_resume(job);
 708         }
 709         job->user_paused = false;
 710         assert(job->pause_count > 0);
 711         job->pause_count--;
 712     }
 713     job->cancelled = true;
 714     /* To prevent 'force == false' overriding a previous 'force == true' */
 715     job->force_cancel |= force;
 716 }
 717
 718 static void job_completed_txn_abort(Job *job)
 719 {
 720     AioContext *ctx;
 721     JobTxn *txn = job->txn;
 722     Job *other_job;
 723
 724     if (txn->aborting) {
 725         /*
 726          * We are cancelled by another job, which will handle everything.
 727          */
 728         return;
 729     }
 730     txn->aborting = true;
 731     job_txn_ref(txn);
 732
 733     /* We are the first failed job. Cancel other jobs. */
 734     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 735         ctx = other_job->aio_context;
 736         aio_context_acquire(ctx);
 737     }
 738
 739     /* Other jobs are effectively cancelled by us, set the status for
 740      * them; this job, however, may or may not be cancelled, depending
 741      * on the caller, so leave it. */
 742     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 743         if (other_job != job) {
 744             job_cancel_async(other_job, false);
 745         }
 746     }
 747     while (!QLIST_EMPTY(&txn->jobs)) {
 748         other_job = QLIST_FIRST(&txn->jobs);
 749         ctx = other_job->aio_context;
 750         if (!job_is_completed(other_job)) {
 751             assert(job_is_cancelled(other_job));
 752             job_finish_sync(other_job, NULL, NULL);
 753         }
 754         job_finalize_single(other_job);
 755         aio_context_release(ctx);
 756     }
 757
 758     job_txn_unref(txn);
 759 }
 760
 761 static int job_prepare(Job *job)
 762 {
 763     if (job->ret == 0 && job->driver->prepare) {
 764         job->ret = job->driver->prepare(job);
 765         job_update_rc(job);
 766     }
 767     return job->ret;
 768 }
 769
 770 static int job_needs_finalize(Job *job)
 771 {
 772     return !job->auto_finalize;
 773 }
 774
 775 static void job_do_finalize(Job *job)
 776 {
 777     int rc;
 778     assert(job && job->txn);
 779
 780     /* prepare the transaction to complete */
 781     rc = job_txn_apply(job->txn, job_prepare);
 782     if (rc) {
 783         job_completed_txn_abort(job);
 784     } else {
 785         job_txn_apply(job->txn, job_finalize_single);
 786     }
 787 }
 788
 789 void job_finalize(Job *job, Error **errp)
 790 {
 791     assert(job && job->id);
 792     if (job_apply_verb(job, JOB_VERB_FINALIZE, errp)) {
 793         return;
 794     }
 795     job_do_finalize(job);
 796 }
 797
 798 static int job_transition_to_pending(Job *job)
 799 {
 800     job_state_transition(job, JOB_STATUS_PENDING);
 801     if (!job->auto_finalize) {
 802         job_event_pending(job);
 803     }
 804     return 0;
 805 }
 806
 807 void job_transition_to_ready(Job *job)
 808 {
 809     job_state_transition(job, JOB_STATUS_READY);
 810     job_event_ready(job);
 811 }
 812
 813 static void job_completed_txn_success(Job *job)
 814 {
 815     JobTxn *txn = job->txn;
 816     Job *other_job;
 817
 818     job_state_transition(job, JOB_STATUS_WAITING);
 819
 820     /*
 821      * Successful completion, see if there are other running jobs in this
 822      * txn.
 823      */
 824     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 825         if (!job_is_completed(other_job)) {
 826             return;
 827         }
 828         assert(other_job->ret == 0);
 829     }
 830
 831     job_txn_apply(txn, job_transition_to_pending);
 832
 833     /* If no jobs need manual finalization, automatically do so */
 834     if (job_txn_apply(txn, job_needs_finalize) == 0) {
 835         job_do_finalize(job);
 836     }
 837 }
 838
 839 static void job_completed(Job *job)
 840 {
 841     assert(job && job->txn && !job_is_completed(job));
 842
 843     job_update_rc(job);
 844     trace_job_completed(job, job->ret);
 845     if (job->ret) {
 846         job_completed_txn_abort(job);
 847     } else {
 848         job_completed_txn_success(job);
 849     }
 850 }
 851
 852 /** Useful only as a type shim for aio_bh_schedule_oneshot. */
 853 static void job_exit(void *opaque)
 854 {
 855     Job *job = (Job *)opaque;
 856     AioContext *ctx = job->aio_context;
 857
 858     aio_context_acquire(ctx);
 859     job_completed(job);
 860     aio_context_release(ctx);
 861 }
 862
 863 /**
 864  * All jobs must allow a pause point before entering their job proper. This
 865  * ensures that jobs can be paused prior to being started, then resumed later.
 866  */
 867 static void coroutine_fn job_co_entry(void *opaque)
 868 {
 869     Job *job = opaque;
 870
 871     assert(job && job->driver && job->driver->run);
 872     job_pause_point(job);
 873     job->ret = job->driver->run(job, &job->err);
 874     job_event_idle(job);
 875     job->deferred_to_main_loop = true;
 876     aio_bh_schedule_oneshot(qemu_get_aio_context(), job_exit, job);
 877 }
 878
 879 void job_start(Job *job)
 880 {
 881     assert(job && !job_started(job) && job->paused &&
 882            job->driver && job->driver->run);
 883     job->co = qemu_coroutine_create(job_co_entry, job);
 884     job->pause_count--;
 885     job->busy = true;
 886     job->paused = false;
 887     job_state_transition(job, JOB_STATUS_RUNNING);
 888     aio_co_enter(job->aio_context, job->co);
 889 }
 890
 891 void job_cancel(Job *job, bool force)
 892 {
 893     if (job->status == JOB_STATUS_CONCLUDED) {
 894         job_do_dismiss(job);
 895         return;
 896     }
 897     job_cancel_async(job, force);
 898     if (!job_started(job)) {
 899         job_completed(job);
 900     } else if (job->deferred_to_main_loop) {
 901         job_completed_txn_abort(job);
 902     } else {
 903         job_enter(job);
 904     }
 905 }
 906
 907 void job_user_cancel(Job *job, bool force, Error **errp)
 908 {
 909     if (job_apply_verb(job, JOB_VERB_CANCEL, errp)) {
 910         return;
 911     }
 912     job_cancel(job, force);
 913 }
 914
 915 /* A wrapper around job_cancel() taking an Error ** parameter so it may be
 916  * used with job_finish_sync() without the need for (rather nasty) function
 917  * pointer casts there. */
 918 static void job_cancel_err(Job *job, Error **errp)
 919 {
 920     job_cancel(job, false);
 921 }
 922
 923 int job_cancel_sync(Job *job)
 924 {
 925     return job_finish_sync(job, &job_cancel_err, NULL);
 926 }
 927
 928 void job_cancel_sync_all(void)
 929 {
 930     Job *job;
 931     AioContext *aio_context;
 932
 933     while ((job = job_next(NULL))) {
 934         aio_context = job->aio_context;
 935         aio_context_acquire(aio_context);
 936         job_cancel_sync(job);
 937         aio_context_release(aio_context);
 938     }
 939 }
 940
 941 int job_complete_sync(Job *job, Error **errp)
 942 {
 943     return job_finish_sync(job, job_complete, errp);
 944 }
 945
 946 void job_complete(Job *job, Error **errp)
 947 {
 948     /* Should not be reachable via external interface for internal jobs */
 949     assert(job->id);
 950     if (job_apply_verb(job, JOB_VERB_COMPLETE, errp)) {
 951         return;
 952     }
 953     if (job->pause_count || job_is_cancelled(job) || !job->driver->complete) {
 954         error_setg(errp, "The active block job '%s' cannot be completed",
 955                    job->id);
 956         return;
 957     }
 958
 959     job->driver->complete(job, errp);
 960 }
 961
 962 int job_finish_sync(Job *job, void (*finish)(Job *, Error **errp), Error **errp)
 963 {
 964     Error *local_err = NULL;
 965     int ret;
 966
 967     job_ref(job);
 968
 969     if (finish) {
 970         finish(job, &local_err);
 971     }
 972     if (local_err) {
 973         error_propagate(errp, local_err);
 974         job_unref(job);
 975         return -EBUSY;
 976     }
 977     /* job_drain calls job_enter, and it should be enough to induce progress
 978      * until the job completes or moves to the main thread. */
 979     while (!job->deferred_to_main_loop && !job_is_completed(job)) {
 980         job_drain(job);
 981     }
 982     while (!job_is_completed(job)) {
 983         aio_poll(qemu_get_aio_context(), true);
 984     }
 985     ret = (job_is_cancelled(job) && job->ret == 0) ? -ECANCELED : job->ret;
 986     job_unref(job);
 987     return ret;
 988 }