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 *), bool lock)
 140 {
 141     AioContext *ctx;
 142     Job *job, *next;
 143     int rc = 0;
 144
 145     QLIST_FOREACH_SAFE(job, &txn->jobs, txn_list, next) {
 146         if (lock) {
 147             ctx = job->aio_context;
 148             aio_context_acquire(ctx);
 149         }
 150         rc = fn(job);
 151         if (lock) {
 152             aio_context_release(ctx);
 153         }
 154         if (rc) {
 155             break;
 156         }
 157     }
 158     return rc;
 159 }
 160
 161 bool job_is_internal(Job *job)
 162 {
 163     return (job->id == NULL);
 164 }
 165
 166 static void job_state_transition(Job *job, JobStatus s1)
 167 {
 168     JobStatus s0 = job->status;
 169     assert(s1 >= 0 && s1 <= JOB_STATUS__MAX);
 170     trace_job_state_transition(job, job->ret,
 171                                JobSTT[s0][s1] ? "allowed" : "disallowed",
 172                                JobStatus_str(s0), JobStatus_str(s1));
 173     assert(JobSTT[s0][s1]);
 174     job->status = s1;
 175
 176     if (!job_is_internal(job) && s1 != s0) {
 177         qapi_event_send_job_status_change(job->id, job->status, &error_abort);
 178     }
 179 }
 180
 181 int job_apply_verb(Job *job, JobVerb verb, Error **errp)
 182 {
 183     JobStatus s0 = job->status;
 184     assert(verb >= 0 && verb <= JOB_VERB__MAX);
 185     trace_job_apply_verb(job, JobStatus_str(s0), JobVerb_str(verb),
 186                          JobVerbTable[verb][s0] ? "allowed" : "prohibited");
 187     if (JobVerbTable[verb][s0]) {
 188         return 0;
 189     }
 190     error_setg(errp, "Job '%s' in state '%s' cannot accept command verb '%s'",
 191                job->id, JobStatus_str(s0), JobVerb_str(verb));
 192     return -EPERM;
 193 }
 194
 195 JobType job_type(const Job *job)
 196 {
 197     return job->driver->job_type;
 198 }
 199
 200 const char *job_type_str(const Job *job)
 201 {
 202     return JobType_str(job_type(job));
 203 }
 204
 205 bool job_is_cancelled(Job *job)
 206 {
 207     return job->cancelled;
 208 }
 209
 210 bool job_is_ready(Job *job)
 211 {
 212     switch (job->status) {
 213     case JOB_STATUS_UNDEFINED:
 214     case JOB_STATUS_CREATED:
 215     case JOB_STATUS_RUNNING:
 216     case JOB_STATUS_PAUSED:
 217     case JOB_STATUS_WAITING:
 218     case JOB_STATUS_PENDING:
 219     case JOB_STATUS_ABORTING:
 220     case JOB_STATUS_CONCLUDED:
 221     case JOB_STATUS_NULL:
 222         return false;
 223     case JOB_STATUS_READY:
 224     case JOB_STATUS_STANDBY:
 225         return true;
 226     default:
 227         g_assert_not_reached();
 228     }
 229     return false;
 230 }
 231
 232 bool job_is_completed(Job *job)
 233 {
 234     switch (job->status) {
 235     case JOB_STATUS_UNDEFINED:
 236     case JOB_STATUS_CREATED:
 237     case JOB_STATUS_RUNNING:
 238     case JOB_STATUS_PAUSED:
 239     case JOB_STATUS_READY:
 240     case JOB_STATUS_STANDBY:
 241         return false;
 242     case JOB_STATUS_WAITING:
 243     case JOB_STATUS_PENDING:
 244     case JOB_STATUS_ABORTING:
 245     case JOB_STATUS_CONCLUDED:
 246     case JOB_STATUS_NULL:
 247         return true;
 248     default:
 249         g_assert_not_reached();
 250     }
 251     return false;
 252 }
 253
 254 static bool job_started(Job *job)
 255 {
 256     return job->co;
 257 }
 258
 259 static bool job_should_pause(Job *job)
 260 {
 261     return job->pause_count > 0;
 262 }
 263
 264 Job *job_next(Job *job)
 265 {
 266     if (!job) {
 267         return QLIST_FIRST(&jobs);
 268     }
 269     return QLIST_NEXT(job, job_list);
 270 }
 271
 272 Job *job_get(const char *id)
 273 {
 274     Job *job;
 275
 276     QLIST_FOREACH(job, &jobs, job_list) {
 277         if (job->id && !strcmp(id, job->id)) {
 278             return job;
 279         }
 280     }
 281
 282     return NULL;
 283 }
 284
 285 static void job_sleep_timer_cb(void *opaque)
 286 {
 287     Job *job = opaque;
 288
 289     job_enter(job);
 290 }
 291
 292 void *job_create(const char *job_id, const JobDriver *driver, JobTxn *txn,
 293                  AioContext *ctx, int flags, BlockCompletionFunc *cb,
 294                  void *opaque, Error **errp)
 295 {
 296     Job *job;
 297
 298     if (job_id) {
 299         if (flags & JOB_INTERNAL) {
 300             error_setg(errp, "Cannot specify job ID for internal job");
 301             return NULL;
 302         }
 303         if (!id_wellformed(job_id)) {
 304             error_setg(errp, "Invalid job ID '%s'", job_id);
 305             return NULL;
 306         }
 307         if (job_get(job_id)) {
 308             error_setg(errp, "Job ID '%s' already in use", job_id);
 309             return NULL;
 310         }
 311     } else if (!(flags & JOB_INTERNAL)) {
 312         error_setg(errp, "An explicit job ID is required");
 313         return NULL;
 314     }
 315
 316     job = g_malloc0(driver->instance_size);
 317     job->driver        = driver;
 318     job->id            = g_strdup(job_id);
 319     job->refcnt        = 1;
 320     job->aio_context   = ctx;
 321     job->busy          = false;
 322     job->paused        = true;
 323     job->pause_count   = 1;
 324     job->auto_finalize = !(flags & JOB_MANUAL_FINALIZE);
 325     job->auto_dismiss  = !(flags & JOB_MANUAL_DISMISS);
 326     job->cb            = cb;
 327     job->opaque        = opaque;
 328
 329     notifier_list_init(&job->on_finalize_cancelled);
 330     notifier_list_init(&job->on_finalize_completed);
 331     notifier_list_init(&job->on_pending);
 332     notifier_list_init(&job->on_ready);
 333
 334     job_state_transition(job, JOB_STATUS_CREATED);
 335     aio_timer_init(qemu_get_aio_context(), &job->sleep_timer,
 336                    QEMU_CLOCK_REALTIME, SCALE_NS,
 337                    job_sleep_timer_cb, job);
 338
 339     QLIST_INSERT_HEAD(&jobs, job, job_list);
 340
 341     /* Single jobs are modeled as single-job transactions for sake of
 342      * consolidating the job management logic */
 343     if (!txn) {
 344         txn = job_txn_new();
 345         job_txn_add_job(txn, job);
 346         job_txn_unref(txn);
 347     } else {
 348         job_txn_add_job(txn, job);
 349     }
 350
 351     return job;
 352 }
 353
 354 void job_ref(Job *job)
 355 {
 356     ++job->refcnt;
 357 }
 358
 359 void job_unref(Job *job)
 360 {
 361     if (--job->refcnt == 0) {
 362         assert(job->status == JOB_STATUS_NULL);
 363         assert(!timer_pending(&job->sleep_timer));
 364         assert(!job->txn);
 365
 366         if (job->driver->free) {
 367             job->driver->free(job);
 368         }
 369
 370         QLIST_REMOVE(job, job_list);
 371
 372         g_free(job->id);
 373         g_free(job);
 374     }
 375 }
 376
 377 void job_progress_update(Job *job, uint64_t done)
 378 {
 379     job->progress_current += done;
 380 }
 381
 382 void job_progress_set_remaining(Job *job, uint64_t remaining)
 383 {
 384     job->progress_total = job->progress_current + remaining;
 385 }
 386
 387 void job_event_cancelled(Job *job)
 388 {
 389     notifier_list_notify(&job->on_finalize_cancelled, job);
 390 }
 391
 392 void job_event_completed(Job *job)
 393 {
 394     notifier_list_notify(&job->on_finalize_completed, job);
 395 }
 396
 397 static void job_event_pending(Job *job)
 398 {
 399     notifier_list_notify(&job->on_pending, job);
 400 }
 401
 402 static void job_event_ready(Job *job)
 403 {
 404     notifier_list_notify(&job->on_ready, job);
 405 }
 406
 407 void job_enter_cond(Job *job, bool(*fn)(Job *job))
 408 {
 409     if (!job_started(job)) {
 410         return;
 411     }
 412     if (job->deferred_to_main_loop) {
 413         return;
 414     }
 415
 416     job_lock();
 417     if (job->busy) {
 418         job_unlock();
 419         return;
 420     }
 421
 422     if (fn && !fn(job)) {
 423         job_unlock();
 424         return;
 425     }
 426
 427     assert(!job->deferred_to_main_loop);
 428     timer_del(&job->sleep_timer);
 429     job->busy = true;
 430     job_unlock();
 431     aio_co_wake(job->co);
 432 }
 433
 434 void job_enter(Job *job)
 435 {
 436     job_enter_cond(job, NULL);
 437 }
 438
 439 /* Yield, and schedule a timer to reenter the coroutine after @ns nanoseconds.
 440  * Reentering the job coroutine with job_enter() before the timer has expired
 441  * is allowed and cancels the timer.
 442  *
 443  * If @ns is (uint64_t) -1, no timer is scheduled and job_enter() must be
 444  * called explicitly. */
 445 static void coroutine_fn job_do_yield(Job *job, uint64_t ns)
 446 {
 447     job_lock();
 448     if (ns != -1) {
 449         timer_mod(&job->sleep_timer, ns);
 450     }
 451     job->busy = false;
 452     job_unlock();
 453     qemu_coroutine_yield();
 454
 455     /* Set by job_enter_cond() before re-entering the coroutine.  */
 456     assert(job->busy);
 457 }
 458
 459 void coroutine_fn job_pause_point(Job *job)
 460 {
 461     assert(job && job_started(job));
 462
 463     if (!job_should_pause(job)) {
 464         return;
 465     }
 466     if (job_is_cancelled(job)) {
 467         return;
 468     }
 469
 470     if (job->driver->pause) {
 471         job->driver->pause(job);
 472     }
 473
 474     if (job_should_pause(job) && !job_is_cancelled(job)) {
 475         JobStatus status = job->status;
 476         job_state_transition(job, status == JOB_STATUS_READY
 477                                   ? JOB_STATUS_STANDBY
 478                                   : JOB_STATUS_PAUSED);
 479         job->paused = true;
 480         job_do_yield(job, -1);
 481         job->paused = false;
 482         job_state_transition(job, status);
 483     }
 484
 485     if (job->driver->resume) {
 486         job->driver->resume(job);
 487     }
 488 }
 489
 490 void job_yield(Job *job)
 491 {
 492     assert(job->busy);
 493
 494     /* Check cancellation *before* setting busy = false, too!  */
 495     if (job_is_cancelled(job)) {
 496         return;
 497     }
 498
 499     if (!job_should_pause(job)) {
 500         job_do_yield(job, -1);
 501     }
 502
 503     job_pause_point(job);
 504 }
 505
 506 void coroutine_fn job_sleep_ns(Job *job, int64_t ns)
 507 {
 508     assert(job->busy);
 509
 510     /* Check cancellation *before* setting busy = false, too!  */
 511     if (job_is_cancelled(job)) {
 512         return;
 513     }
 514
 515     if (!job_should_pause(job)) {
 516         job_do_yield(job, qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + ns);
 517     }
 518
 519     job_pause_point(job);
 520 }
 521
 522 void job_drain(Job *job)
 523 {
 524     /* If job is !busy this kicks it into the next pause point. */
 525     job_enter(job);
 526
 527     if (job->driver->drain) {
 528         job->driver->drain(job);
 529     }
 530 }
 531
 532
 533 /**
 534  * All jobs must allow a pause point before entering their job proper. This
 535  * ensures that jobs can be paused prior to being started, then resumed later.
 536  */
 537 static void coroutine_fn job_co_entry(void *opaque)
 538 {
 539     Job *job = opaque;
 540
 541     assert(job && job->driver && job->driver->start);
 542     job_pause_point(job);
 543     job->driver->start(job);
 544 }
 545
 546
 547 void job_start(Job *job)
 548 {
 549     assert(job && !job_started(job) && job->paused &&
 550            job->driver && job->driver->start);
 551     job->co = qemu_coroutine_create(job_co_entry, job);
 552     job->pause_count--;
 553     job->busy = true;
 554     job->paused = false;
 555     job_state_transition(job, JOB_STATUS_RUNNING);
 556     aio_co_enter(job->aio_context, job->co);
 557 }
 558
 559 /* Assumes the block_job_mutex is held */
 560 static bool job_timer_not_pending(Job *job)
 561 {
 562     return !timer_pending(&job->sleep_timer);
 563 }
 564
 565 void job_pause(Job *job)
 566 {
 567     job->pause_count++;
 568 }
 569
 570 void job_resume(Job *job)
 571 {
 572     assert(job->pause_count > 0);
 573     job->pause_count--;
 574     if (job->pause_count) {
 575         return;
 576     }
 577
 578     /* kick only if no timer is pending */
 579     job_enter_cond(job, job_timer_not_pending);
 580 }
 581
 582 void job_user_pause(Job *job, Error **errp)
 583 {
 584     if (job_apply_verb(job, JOB_VERB_PAUSE, errp)) {
 585         return;
 586     }
 587     if (job->user_paused) {
 588         error_setg(errp, "Job is already paused");
 589         return;
 590     }
 591     job->user_paused = true;
 592     job_pause(job);
 593 }
 594
 595 bool job_user_paused(Job *job)
 596 {
 597     return job->user_paused;
 598 }
 599
 600 void job_user_resume(Job *job, Error **errp)
 601 {
 602     assert(job);
 603     if (!job->user_paused || job->pause_count <= 0) {
 604         error_setg(errp, "Can't resume a job that was not paused");
 605         return;
 606     }
 607     if (job_apply_verb(job, JOB_VERB_RESUME, errp)) {
 608         return;
 609     }
 610     if (job->driver->user_resume) {
 611         job->driver->user_resume(job);
 612     }
 613     job->user_paused = false;
 614     job_resume(job);
 615 }
 616
 617 static void job_do_dismiss(Job *job)
 618 {
 619     assert(job);
 620     job->busy = false;
 621     job->paused = false;
 622     job->deferred_to_main_loop = true;
 623
 624     job_txn_del_job(job);
 625
 626     job_state_transition(job, JOB_STATUS_NULL);
 627     job_unref(job);
 628 }
 629
 630 void job_dismiss(Job **jobptr, Error **errp)
 631 {
 632     Job *job = *jobptr;
 633     /* similarly to _complete, this is QMP-interface only. */
 634     assert(job->id);
 635     if (job_apply_verb(job, JOB_VERB_DISMISS, errp)) {
 636         return;
 637     }
 638
 639     job_do_dismiss(job);
 640     *jobptr = NULL;
 641 }
 642
 643 void job_early_fail(Job *job)
 644 {
 645     assert(job->status == JOB_STATUS_CREATED);
 646     job_do_dismiss(job);
 647 }
 648
 649 static void job_conclude(Job *job)
 650 {
 651     job_state_transition(job, JOB_STATUS_CONCLUDED);
 652     if (job->auto_dismiss || !job_started(job)) {
 653         job_do_dismiss(job);
 654     }
 655 }
 656
 657 static void job_update_rc(Job *job)
 658 {
 659     if (!job->ret && job_is_cancelled(job)) {
 660         job->ret = -ECANCELED;
 661     }
 662     if (job->ret) {
 663         job_state_transition(job, JOB_STATUS_ABORTING);
 664     }
 665 }
 666
 667 static void job_commit(Job *job)
 668 {
 669     assert(!job->ret);
 670     if (job->driver->commit) {
 671         job->driver->commit(job);
 672     }
 673 }
 674
 675 static void job_abort(Job *job)
 676 {
 677     assert(job->ret);
 678     if (job->driver->abort) {
 679         job->driver->abort(job);
 680     }
 681 }
 682
 683 static void job_clean(Job *job)
 684 {
 685     if (job->driver->clean) {
 686         job->driver->clean(job);
 687     }
 688 }
 689
 690 static int job_finalize_single(Job *job)
 691 {
 692     assert(job_is_completed(job));
 693
 694     /* Ensure abort is called for late-transactional failures */
 695     job_update_rc(job);
 696
 697     if (!job->ret) {
 698         job_commit(job);
 699     } else {
 700         job_abort(job);
 701     }
 702     job_clean(job);
 703
 704     if (job->cb) {
 705         job->cb(job->opaque, job->ret);
 706     }
 707
 708     /* Emit events only if we actually started */
 709     if (job_started(job)) {
 710         if (job_is_cancelled(job)) {
 711             job_event_cancelled(job);
 712         } else {
 713             job_event_completed(job);
 714         }
 715     }
 716
 717     job_txn_del_job(job);
 718     job_conclude(job);
 719     return 0;
 720 }
 721
 722 static void job_cancel_async(Job *job, bool force)
 723 {
 724     if (job->user_paused) {
 725         /* Do not call job_enter here, the caller will handle it.  */
 726         job->user_paused = false;
 727         if (job->driver->user_resume) {
 728             job->driver->user_resume(job);
 729         }
 730         assert(job->pause_count > 0);
 731         job->pause_count--;
 732     }
 733     job->cancelled = true;
 734     /* To prevent 'force == false' overriding a previous 'force == true' */
 735     job->force_cancel |= force;
 736 }
 737
 738 static void job_completed_txn_abort(Job *job)
 739 {
 740     AioContext *ctx;
 741     JobTxn *txn = job->txn;
 742     Job *other_job;
 743
 744     if (txn->aborting) {
 745         /*
 746          * We are cancelled by another job, which will handle everything.
 747          */
 748         return;
 749     }
 750     txn->aborting = true;
 751     job_txn_ref(txn);
 752
 753     /* We are the first failed job. Cancel other jobs. */
 754     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 755         ctx = other_job->aio_context;
 756         aio_context_acquire(ctx);
 757     }
 758
 759     /* Other jobs are effectively cancelled by us, set the status for
 760      * them; this job, however, may or may not be cancelled, depending
 761      * on the caller, so leave it. */
 762     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 763         if (other_job != job) {
 764             job_cancel_async(other_job, false);
 765         }
 766     }
 767     while (!QLIST_EMPTY(&txn->jobs)) {
 768         other_job = QLIST_FIRST(&txn->jobs);
 769         ctx = other_job->aio_context;
 770         if (!job_is_completed(other_job)) {
 771             assert(job_is_cancelled(other_job));
 772             job_finish_sync(other_job, NULL, NULL);
 773         }
 774         job_finalize_single(other_job);
 775         aio_context_release(ctx);
 776     }
 777
 778     job_txn_unref(txn);
 779 }
 780
 781 static int job_prepare(Job *job)
 782 {
 783     if (job->ret == 0 && job->driver->prepare) {
 784         job->ret = job->driver->prepare(job);
 785     }
 786     return job->ret;
 787 }
 788
 789 static int job_needs_finalize(Job *job)
 790 {
 791     return !job->auto_finalize;
 792 }
 793
 794 static void job_do_finalize(Job *job)
 795 {
 796     int rc;
 797     assert(job && job->txn);
 798
 799     /* prepare the transaction to complete */
 800     rc = job_txn_apply(job->txn, job_prepare, true);
 801     if (rc) {
 802         job_completed_txn_abort(job);
 803     } else {
 804         job_txn_apply(job->txn, job_finalize_single, true);
 805     }
 806 }
 807
 808 void job_finalize(Job *job, Error **errp)
 809 {
 810     assert(job && job->id);
 811     if (job_apply_verb(job, JOB_VERB_FINALIZE, errp)) {
 812         return;
 813     }
 814     job_do_finalize(job);
 815 }
 816
 817 static int job_transition_to_pending(Job *job)
 818 {
 819     job_state_transition(job, JOB_STATUS_PENDING);
 820     if (!job->auto_finalize) {
 821         job_event_pending(job);
 822     }
 823     return 0;
 824 }
 825
 826 void job_transition_to_ready(Job *job)
 827 {
 828     job_state_transition(job, JOB_STATUS_READY);
 829     job_event_ready(job);
 830 }
 831
 832 static void job_completed_txn_success(Job *job)
 833 {
 834     JobTxn *txn = job->txn;
 835     Job *other_job;
 836
 837     job_state_transition(job, JOB_STATUS_WAITING);
 838
 839     /*
 840      * Successful completion, see if there are other running jobs in this
 841      * txn.
 842      */
 843     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 844         if (!job_is_completed(other_job)) {
 845             return;
 846         }
 847         assert(other_job->ret == 0);
 848     }
 849
 850     job_txn_apply(txn, job_transition_to_pending, false);
 851
 852     /* If no jobs need manual finalization, automatically do so */
 853     if (job_txn_apply(txn, job_needs_finalize, false) == 0) {
 854         job_do_finalize(job);
 855     }
 856 }
 857
 858 void job_completed(Job *job, int ret)
 859 {
 860     assert(job && job->txn && !job_is_completed(job));
 861     job->ret = ret;
 862     job_update_rc(job);
 863     trace_job_completed(job, ret, job->ret);
 864     if (job->ret) {
 865         job_completed_txn_abort(job);
 866     } else {
 867         job_completed_txn_success(job);
 868     }
 869 }
 870
 871 void job_cancel(Job *job, bool force)
 872 {
 873     if (job->status == JOB_STATUS_CONCLUDED) {
 874         job_do_dismiss(job);
 875         return;
 876     }
 877     job_cancel_async(job, force);
 878     if (!job_started(job)) {
 879         job_completed(job, -ECANCELED);
 880     } else if (job->deferred_to_main_loop) {
 881         job_completed_txn_abort(job);
 882     } else {
 883         job_enter(job);
 884     }
 885 }
 886
 887 void job_user_cancel(Job *job, bool force, Error **errp)
 888 {
 889     if (job_apply_verb(job, JOB_VERB_CANCEL, errp)) {
 890         return;
 891     }
 892     job_cancel(job, force);
 893 }
 894
 895 /* A wrapper around job_cancel() taking an Error ** parameter so it may be
 896  * used with job_finish_sync() without the need for (rather nasty) function
 897  * pointer casts there. */
 898 static void job_cancel_err(Job *job, Error **errp)
 899 {
 900     job_cancel(job, false);
 901 }
 902
 903 int job_cancel_sync(Job *job)
 904 {
 905     return job_finish_sync(job, &job_cancel_err, NULL);
 906 }
 907
 908 void job_cancel_sync_all(void)
 909 {
 910     Job *job;
 911     AioContext *aio_context;
 912
 913     while ((job = job_next(NULL))) {
 914         aio_context = job->aio_context;
 915         aio_context_acquire(aio_context);
 916         job_cancel_sync(job);
 917         aio_context_release(aio_context);
 918     }
 919 }
 920
 921 int job_complete_sync(Job *job, Error **errp)
 922 {
 923     return job_finish_sync(job, job_complete, errp);
 924 }
 925
 926 void job_complete(Job *job, Error **errp)
 927 {
 928     /* Should not be reachable via external interface for internal jobs */
 929     assert(job->id);
 930     if (job_apply_verb(job, JOB_VERB_COMPLETE, errp)) {
 931         return;
 932     }
 933     if (job->pause_count || job_is_cancelled(job) || !job->driver->complete) {
 934         error_setg(errp, "The active block job '%s' cannot be completed",
 935                    job->id);
 936         return;
 937     }
 938
 939     job->driver->complete(job, errp);
 940 }
 941
 942
 943 typedef struct {
 944     Job *job;
 945     JobDeferToMainLoopFn *fn;
 946     void *opaque;
 947 } JobDeferToMainLoopData;
 948
 949 static void job_defer_to_main_loop_bh(void *opaque)
 950 {
 951     JobDeferToMainLoopData *data = opaque;
 952     Job *job = data->job;
 953     AioContext *aio_context = job->aio_context;
 954
 955     aio_context_acquire(aio_context);
 956     data->fn(data->job, data->opaque);
 957     aio_context_release(aio_context);
 958
 959     g_free(data);
 960 }
 961
 962 void job_defer_to_main_loop(Job *job, JobDeferToMainLoopFn *fn, void *opaque)
 963 {
 964     JobDeferToMainLoopData *data = g_malloc(sizeof(*data));
 965     data->job = job;
 966     data->fn = fn;
 967     data->opaque = opaque;
 968     job->deferred_to_main_loop = true;
 969
 970     aio_bh_schedule_oneshot(qemu_get_aio_context(),
 971                             job_defer_to_main_loop_bh, data);
 972 }
 973
 974 int job_finish_sync(Job *job, void (*finish)(Job *, Error **errp), Error **errp)
 975 {
 976     Error *local_err = NULL;
 977     int ret;
 978
 979     job_ref(job);
 980
 981     if (finish) {
 982         finish(job, &local_err);
 983     }
 984     if (local_err) {
 985         error_propagate(errp, local_err);
 986         job_unref(job);
 987         return -EBUSY;
 988     }
 989     /* job_drain calls job_enter, and it should be enough to induce progress
 990      * until the job completes or moves to the main thread. */
 991     while (!job->deferred_to_main_loop && !job_is_completed(job)) {
 992         job_drain(job);
 993     }
 994     while (!job_is_completed(job)) {
 995         aio_poll(qemu_get_aio_context(), true);
 996     }
 997     ret = (job_is_cancelled(job) && job->ret == 0) ? -ECANCELED : job->ret;
 998     job_unref(job);
 999     return ret;
1000 }