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/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, 1, 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(Job *job, int fn(Job *))
 140 {
 141     AioContext *inner_ctx;
 142     Job *other_job, *next;
 143     JobTxn *txn = job->txn;
 144     int rc = 0;
 145
 146     /*
 147      * Similar to job_completed_txn_abort, we take each job's lock before
 148      * applying fn, but since we assume that outer_ctx is held by the caller,
 149      * we need to release it here to avoid holding the lock twice - which would
 150      * break AIO_WAIT_WHILE from within fn.
 151      */
 152     job_ref(job);
 153     aio_context_release(job->aio_context);
 154
 155     QLIST_FOREACH_SAFE(other_job, &txn->jobs, txn_list, next) {
 156         inner_ctx = other_job->aio_context;
 157         aio_context_acquire(inner_ctx);
 158         rc = fn(other_job);
 159         aio_context_release(inner_ctx);
 160         if (rc) {
 161             break;
 162         }
 163     }
 164
 165     /*
 166      * Note that job->aio_context might have been changed by calling fn, so we
 167      * can't use a local variable to cache it.
 168      */
 169     aio_context_acquire(job->aio_context);
 170     job_unref(job);
 171     return rc;
 172 }
 173
 174 bool job_is_internal(Job *job)
 175 {
 176     return (job->id == NULL);
 177 }
 178
 179 static void job_state_transition(Job *job, JobStatus s1)
 180 {
 181     JobStatus s0 = job->status;
 182     assert(s1 >= 0 && s1 < JOB_STATUS__MAX);
 183     trace_job_state_transition(job, job->ret,
 184                                JobSTT[s0][s1] ? "allowed" : "disallowed",
 185                                JobStatus_str(s0), JobStatus_str(s1));
 186     assert(JobSTT[s0][s1]);
 187     job->status = s1;
 188
 189     if (!job_is_internal(job) && s1 != s0) {
 190         qapi_event_send_job_status_change(job->id, job->status);
 191     }
 192 }
 193
 194 int job_apply_verb(Job *job, JobVerb verb, Error **errp)
 195 {
 196     JobStatus s0 = job->status;
 197     assert(verb >= 0 && verb < JOB_VERB__MAX);
 198     trace_job_apply_verb(job, JobStatus_str(s0), JobVerb_str(verb),
 199                          JobVerbTable[verb][s0] ? "allowed" : "prohibited");
 200     if (JobVerbTable[verb][s0]) {
 201         return 0;
 202     }
 203     error_setg(errp, "Job '%s' in state '%s' cannot accept command verb '%s'",
 204                job->id, JobStatus_str(s0), JobVerb_str(verb));
 205     return -EPERM;
 206 }
 207
 208 JobType job_type(const Job *job)
 209 {
 210     return job->driver->job_type;
 211 }
 212
 213 const char *job_type_str(const Job *job)
 214 {
 215     return JobType_str(job_type(job));
 216 }
 217
 218 bool job_is_cancelled(Job *job)
 219 {
 220     /* force_cancel may be true only if cancelled is true, too */
 221     assert(job->cancelled || !job->force_cancel);
 222     return job->force_cancel;
 223 }
 224
 225 bool job_cancel_requested(Job *job)
 226 {
 227     return job->cancelled;
 228 }
 229
 230 bool job_is_ready(Job *job)
 231 {
 232     switch (job->status) {
 233     case JOB_STATUS_UNDEFINED:
 234     case JOB_STATUS_CREATED:
 235     case JOB_STATUS_RUNNING:
 236     case JOB_STATUS_PAUSED:
 237     case JOB_STATUS_WAITING:
 238     case JOB_STATUS_PENDING:
 239     case JOB_STATUS_ABORTING:
 240     case JOB_STATUS_CONCLUDED:
 241     case JOB_STATUS_NULL:
 242         return false;
 243     case JOB_STATUS_READY:
 244     case JOB_STATUS_STANDBY:
 245         return true;
 246     default:
 247         g_assert_not_reached();
 248     }
 249     return false;
 250 }
 251
 252 bool job_is_completed(Job *job)
 253 {
 254     switch (job->status) {
 255     case JOB_STATUS_UNDEFINED:
 256     case JOB_STATUS_CREATED:
 257     case JOB_STATUS_RUNNING:
 258     case JOB_STATUS_PAUSED:
 259     case JOB_STATUS_READY:
 260     case JOB_STATUS_STANDBY:
 261         return false;
 262     case JOB_STATUS_WAITING:
 263     case JOB_STATUS_PENDING:
 264     case JOB_STATUS_ABORTING:
 265     case JOB_STATUS_CONCLUDED:
 266     case JOB_STATUS_NULL:
 267         return true;
 268     default:
 269         g_assert_not_reached();
 270     }
 271     return false;
 272 }
 273
 274 static bool job_started(Job *job)
 275 {
 276     return job->co;
 277 }
 278
 279 static bool job_should_pause(Job *job)
 280 {
 281     return job->pause_count > 0;
 282 }
 283
 284 Job *job_next(Job *job)
 285 {
 286     if (!job) {
 287         return QLIST_FIRST(&jobs);
 288     }
 289     return QLIST_NEXT(job, job_list);
 290 }
 291
 292 Job *job_get(const char *id)
 293 {
 294     Job *job;
 295
 296     QLIST_FOREACH(job, &jobs, job_list) {
 297         if (job->id && !strcmp(id, job->id)) {
 298             return job;
 299         }
 300     }
 301
 302     return NULL;
 303 }
 304
 305 static void job_sleep_timer_cb(void *opaque)
 306 {
 307     Job *job = opaque;
 308
 309     job_enter(job);
 310 }
 311
 312 void *job_create(const char *job_id, const JobDriver *driver, JobTxn *txn,
 313                  AioContext *ctx, int flags, BlockCompletionFunc *cb,
 314                  void *opaque, Error **errp)
 315 {
 316     Job *job;
 317
 318     if (job_id) {
 319         if (flags & JOB_INTERNAL) {
 320             error_setg(errp, "Cannot specify job ID for internal job");
 321             return NULL;
 322         }
 323         if (!id_wellformed(job_id)) {
 324             error_setg(errp, "Invalid job ID '%s'", job_id);
 325             return NULL;
 326         }
 327         if (job_get(job_id)) {
 328             error_setg(errp, "Job ID '%s' already in use", job_id);
 329             return NULL;
 330         }
 331     } else if (!(flags & JOB_INTERNAL)) {
 332         error_setg(errp, "An explicit job ID is required");
 333         return NULL;
 334     }
 335
 336     job = g_malloc0(driver->instance_size);
 337     job->driver        = driver;
 338     job->id            = g_strdup(job_id);
 339     job->refcnt        = 1;
 340     job->aio_context   = ctx;
 341     job->busy          = false;
 342     job->paused        = true;
 343     job->pause_count   = 1;
 344     job->auto_finalize = !(flags & JOB_MANUAL_FINALIZE);
 345     job->auto_dismiss  = !(flags & JOB_MANUAL_DISMISS);
 346     job->cb            = cb;
 347     job->opaque        = opaque;
 348
 349     progress_init(&job->progress);
 350
 351     notifier_list_init(&job->on_finalize_cancelled);
 352     notifier_list_init(&job->on_finalize_completed);
 353     notifier_list_init(&job->on_pending);
 354     notifier_list_init(&job->on_ready);
 355     notifier_list_init(&job->on_idle);
 356
 357     job_state_transition(job, JOB_STATUS_CREATED);
 358     aio_timer_init(qemu_get_aio_context(), &job->sleep_timer,
 359                    QEMU_CLOCK_REALTIME, SCALE_NS,
 360                    job_sleep_timer_cb, job);
 361
 362     QLIST_INSERT_HEAD(&jobs, job, job_list);
 363
 364     /* Single jobs are modeled as single-job transactions for sake of
 365      * consolidating the job management logic */
 366     if (!txn) {
 367         txn = job_txn_new();
 368         job_txn_add_job(txn, job);
 369         job_txn_unref(txn);
 370     } else {
 371         job_txn_add_job(txn, job);
 372     }
 373
 374     return job;
 375 }
 376
 377 void job_ref(Job *job)
 378 {
 379     ++job->refcnt;
 380 }
 381
 382 void job_unref(Job *job)
 383 {
 384     if (--job->refcnt == 0) {
 385         assert(job->status == JOB_STATUS_NULL);
 386         assert(!timer_pending(&job->sleep_timer));
 387         assert(!job->txn);
 388
 389         if (job->driver->free) {
 390             job->driver->free(job);
 391         }
 392
 393         QLIST_REMOVE(job, job_list);
 394
 395         progress_destroy(&job->progress);
 396         error_free(job->err);
 397         g_free(job->id);
 398         g_free(job);
 399     }
 400 }
 401
 402 void job_progress_update(Job *job, uint64_t done)
 403 {
 404     progress_work_done(&job->progress, done);
 405 }
 406
 407 void job_progress_set_remaining(Job *job, uint64_t remaining)
 408 {
 409     progress_set_remaining(&job->progress, remaining);
 410 }
 411
 412 void job_progress_increase_remaining(Job *job, uint64_t delta)
 413 {
 414     progress_increase_remaining(&job->progress, delta);
 415 }
 416
 417 void job_event_cancelled(Job *job)
 418 {
 419     notifier_list_notify(&job->on_finalize_cancelled, job);
 420 }
 421
 422 void job_event_completed(Job *job)
 423 {
 424     notifier_list_notify(&job->on_finalize_completed, job);
 425 }
 426
 427 static void job_event_pending(Job *job)
 428 {
 429     notifier_list_notify(&job->on_pending, job);
 430 }
 431
 432 static void job_event_ready(Job *job)
 433 {
 434     notifier_list_notify(&job->on_ready, job);
 435 }
 436
 437 static void job_event_idle(Job *job)
 438 {
 439     notifier_list_notify(&job->on_idle, job);
 440 }
 441
 442 void job_enter_cond(Job *job, bool(*fn)(Job *job))
 443 {
 444     if (!job_started(job)) {
 445         return;
 446     }
 447     if (job->deferred_to_main_loop) {
 448         return;
 449     }
 450
 451     job_lock();
 452     if (job->busy) {
 453         job_unlock();
 454         return;
 455     }
 456
 457     if (fn && !fn(job)) {
 458         job_unlock();
 459         return;
 460     }
 461
 462     assert(!job->deferred_to_main_loop);
 463     timer_del(&job->sleep_timer);
 464     job->busy = true;
 465     job_unlock();
 466     aio_co_enter(job->aio_context, job->co);
 467 }
 468
 469 void job_enter(Job *job)
 470 {
 471     job_enter_cond(job, NULL);
 472 }
 473
 474 /* Yield, and schedule a timer to reenter the coroutine after @ns nanoseconds.
 475  * Reentering the job coroutine with job_enter() before the timer has expired
 476  * is allowed and cancels the timer.
 477  *
 478  * If @ns is (uint64_t) -1, no timer is scheduled and job_enter() must be
 479  * called explicitly. */
 480 static void coroutine_fn job_do_yield(Job *job, uint64_t ns)
 481 {
 482     job_lock();
 483     if (ns != -1) {
 484         timer_mod(&job->sleep_timer, ns);
 485     }
 486     job->busy = false;
 487     job_event_idle(job);
 488     job_unlock();
 489     qemu_coroutine_yield();
 490
 491     /* Set by job_enter_cond() before re-entering the coroutine.  */
 492     assert(job->busy);
 493 }
 494
 495 void coroutine_fn job_pause_point(Job *job)
 496 {
 497     assert(job && job_started(job));
 498
 499     if (!job_should_pause(job)) {
 500         return;
 501     }
 502     if (job_is_cancelled(job)) {
 503         return;
 504     }
 505
 506     if (job->driver->pause) {
 507         job->driver->pause(job);
 508     }
 509
 510     if (job_should_pause(job) && !job_is_cancelled(job)) {
 511         JobStatus status = job->status;
 512         job_state_transition(job, status == JOB_STATUS_READY
 513                                   ? JOB_STATUS_STANDBY
 514                                   : JOB_STATUS_PAUSED);
 515         job->paused = true;
 516         job_do_yield(job, -1);
 517         job->paused = false;
 518         job_state_transition(job, status);
 519     }
 520
 521     if (job->driver->resume) {
 522         job->driver->resume(job);
 523     }
 524 }
 525
 526 void job_yield(Job *job)
 527 {
 528     assert(job->busy);
 529
 530     /* Check cancellation *before* setting busy = false, too!  */
 531     if (job_is_cancelled(job)) {
 532         return;
 533     }
 534
 535     if (!job_should_pause(job)) {
 536         job_do_yield(job, -1);
 537     }
 538
 539     job_pause_point(job);
 540 }
 541
 542 void coroutine_fn job_sleep_ns(Job *job, int64_t ns)
 543 {
 544     assert(job->busy);
 545
 546     /* Check cancellation *before* setting busy = false, too!  */
 547     if (job_is_cancelled(job)) {
 548         return;
 549     }
 550
 551     if (!job_should_pause(job)) {
 552         job_do_yield(job, qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + ns);
 553     }
 554
 555     job_pause_point(job);
 556 }
 557
 558 /* Assumes the block_job_mutex is held */
 559 static bool job_timer_not_pending(Job *job)
 560 {
 561     return !timer_pending(&job->sleep_timer);
 562 }
 563
 564 void job_pause(Job *job)
 565 {
 566     job->pause_count++;
 567     if (!job->paused) {
 568         job_enter(job);
 569     }
 570 }
 571
 572 void job_resume(Job *job)
 573 {
 574     assert(job->pause_count > 0);
 575     job->pause_count--;
 576     if (job->pause_count) {
 577         return;
 578     }
 579
 580     /* kick only if no timer is pending */
 581     job_enter_cond(job, job_timer_not_pending);
 582 }
 583
 584 void job_user_pause(Job *job, Error **errp)
 585 {
 586     if (job_apply_verb(job, JOB_VERB_PAUSE, errp)) {
 587         return;
 588     }
 589     if (job->user_paused) {
 590         error_setg(errp, "Job is already paused");
 591         return;
 592     }
 593     job->user_paused = true;
 594     job_pause(job);
 595 }
 596
 597 bool job_user_paused(Job *job)
 598 {
 599     return job->user_paused;
 600 }
 601
 602 void job_user_resume(Job *job, Error **errp)
 603 {
 604     assert(job);
 605     if (!job->user_paused || job->pause_count <= 0) {
 606         error_setg(errp, "Can't resume a job that was not paused");
 607         return;
 608     }
 609     if (job_apply_verb(job, JOB_VERB_RESUME, errp)) {
 610         return;
 611     }
 612     if (job->driver->user_resume) {
 613         job->driver->user_resume(job);
 614     }
 615     job->user_paused = false;
 616     job_resume(job);
 617 }
 618
 619 static void job_do_dismiss(Job *job)
 620 {
 621     assert(job);
 622     job->busy = false;
 623     job->paused = false;
 624     job->deferred_to_main_loop = true;
 625
 626     job_txn_del_job(job);
 627
 628     job_state_transition(job, JOB_STATUS_NULL);
 629     job_unref(job);
 630 }
 631
 632 void job_dismiss(Job **jobptr, Error **errp)
 633 {
 634     Job *job = *jobptr;
 635     /* similarly to _complete, this is QMP-interface only. */
 636     assert(job->id);
 637     if (job_apply_verb(job, JOB_VERB_DISMISS, errp)) {
 638         return;
 639     }
 640
 641     job_do_dismiss(job);
 642     *jobptr = NULL;
 643 }
 644
 645 void job_early_fail(Job *job)
 646 {
 647     assert(job->status == JOB_STATUS_CREATED);
 648     job_do_dismiss(job);
 649 }
 650
 651 static void job_conclude(Job *job)
 652 {
 653     job_state_transition(job, JOB_STATUS_CONCLUDED);
 654     if (job->auto_dismiss || !job_started(job)) {
 655         job_do_dismiss(job);
 656     }
 657 }
 658
 659 static void job_update_rc(Job *job)
 660 {
 661     if (!job->ret && job_is_cancelled(job)) {
 662         job->ret = -ECANCELED;
 663     }
 664     if (job->ret) {
 665         if (!job->err) {
 666             error_setg(&job->err, "%s", strerror(-job->ret));
 667         }
 668         job_state_transition(job, JOB_STATUS_ABORTING);
 669     }
 670 }
 671
 672 static void job_commit(Job *job)
 673 {
 674     assert(!job->ret);
 675     if (job->driver->commit) {
 676         job->driver->commit(job);
 677     }
 678 }
 679
 680 static void job_abort(Job *job)
 681 {
 682     assert(job->ret);
 683     if (job->driver->abort) {
 684         job->driver->abort(job);
 685     }
 686 }
 687
 688 static void job_clean(Job *job)
 689 {
 690     if (job->driver->clean) {
 691         job->driver->clean(job);
 692     }
 693 }
 694
 695 static int job_finalize_single(Job *job)
 696 {
 697     assert(job_is_completed(job));
 698
 699     /* Ensure abort is called for late-transactional failures */
 700     job_update_rc(job);
 701
 702     if (!job->ret) {
 703         job_commit(job);
 704     } else {
 705         job_abort(job);
 706     }
 707     job_clean(job);
 708
 709     if (job->cb) {
 710         job->cb(job->opaque, job->ret);
 711     }
 712
 713     /* Emit events only if we actually started */
 714     if (job_started(job)) {
 715         if (job_is_cancelled(job)) {
 716             job_event_cancelled(job);
 717         } else {
 718             job_event_completed(job);
 719         }
 720     }
 721
 722     job_txn_del_job(job);
 723     job_conclude(job);
 724     return 0;
 725 }
 726
 727 static void job_cancel_async(Job *job, bool force)
 728 {
 729     if (job->driver->cancel) {
 730         force = job->driver->cancel(job, force);
 731     } else {
 732         /* No .cancel() means the job will behave as if force-cancelled */
 733         force = true;
 734     }
 735
 736     if (job->user_paused) {
 737         /* Do not call job_enter here, the caller will handle it.  */
 738         if (job->driver->user_resume) {
 739             job->driver->user_resume(job);
 740         }
 741         job->user_paused = false;
 742         assert(job->pause_count > 0);
 743         job->pause_count--;
 744     }
 745
 746     /*
 747      * Ignore soft cancel requests after the job is already done
 748      * (We will still invoke job->driver->cancel() above, but if the
 749      * job driver supports soft cancelling and the job is done, that
 750      * should be a no-op, too.  We still call it so it can override
 751      * @force.)
 752      */
 753     if (force || !job->deferred_to_main_loop) {
 754         job->cancelled = true;
 755         /* To prevent 'force == false' overriding a previous 'force == true' */
 756         job->force_cancel |= force;
 757     }
 758 }
 759
 760 static void job_completed_txn_abort(Job *job)
 761 {
 762     AioContext *ctx;
 763     JobTxn *txn = job->txn;
 764     Job *other_job;
 765
 766     if (txn->aborting) {
 767         /*
 768          * We are cancelled by another job, which will handle everything.
 769          */
 770         return;
 771     }
 772     txn->aborting = true;
 773     job_txn_ref(txn);
 774
 775     /*
 776      * We can only hold the single job's AioContext lock while calling
 777      * job_finalize_single() because the finalization callbacks can involve
 778      * calls of AIO_WAIT_WHILE(), which could deadlock otherwise.
 779      * Note that the job's AioContext may change when it is finalized.
 780      */
 781     job_ref(job);
 782     aio_context_release(job->aio_context);
 783
 784     /* Other jobs are effectively cancelled by us, set the status for
 785      * them; this job, however, may or may not be cancelled, depending
 786      * on the caller, so leave it. */
 787     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 788         if (other_job != job) {
 789             ctx = other_job->aio_context;
 790             aio_context_acquire(ctx);
 791             /*
 792              * This is a transaction: If one job failed, no result will matter.
 793              * Therefore, pass force=true to terminate all other jobs as quickly
 794              * as possible.
 795              */
 796             job_cancel_async(other_job, true);
 797             aio_context_release(ctx);
 798         }
 799     }
 800     while (!QLIST_EMPTY(&txn->jobs)) {
 801         other_job = QLIST_FIRST(&txn->jobs);
 802         /*
 803          * The job's AioContext may change, so store it in @ctx so we
 804          * release the same context that we have acquired before.
 805          */
 806         ctx = other_job->aio_context;
 807         aio_context_acquire(ctx);
 808         if (!job_is_completed(other_job)) {
 809             assert(job_cancel_requested(other_job));
 810             job_finish_sync(other_job, NULL, NULL);
 811         }
 812         job_finalize_single(other_job);
 813         aio_context_release(ctx);
 814     }
 815
 816     /*
 817      * Use job_ref()/job_unref() so we can read the AioContext here
 818      * even if the job went away during job_finalize_single().
 819      */
 820     aio_context_acquire(job->aio_context);
 821     job_unref(job);
 822
 823     job_txn_unref(txn);
 824 }
 825
 826 static int job_prepare(Job *job)
 827 {
 828     if (job->ret == 0 && job->driver->prepare) {
 829         job->ret = job->driver->prepare(job);
 830         job_update_rc(job);
 831     }
 832     return job->ret;
 833 }
 834
 835 static int job_needs_finalize(Job *job)
 836 {
 837     return !job->auto_finalize;
 838 }
 839
 840 static void job_do_finalize(Job *job)
 841 {
 842     int rc;
 843     assert(job && job->txn);
 844
 845     /* prepare the transaction to complete */
 846     rc = job_txn_apply(job, job_prepare);
 847     if (rc) {
 848         job_completed_txn_abort(job);
 849     } else {
 850         job_txn_apply(job, job_finalize_single);
 851     }
 852 }
 853
 854 void job_finalize(Job *job, Error **errp)
 855 {
 856     assert(job && job->id);
 857     if (job_apply_verb(job, JOB_VERB_FINALIZE, errp)) {
 858         return;
 859     }
 860     job_do_finalize(job);
 861 }
 862
 863 static int job_transition_to_pending(Job *job)
 864 {
 865     job_state_transition(job, JOB_STATUS_PENDING);
 866     if (!job->auto_finalize) {
 867         job_event_pending(job);
 868     }
 869     return 0;
 870 }
 871
 872 void job_transition_to_ready(Job *job)
 873 {
 874     job_state_transition(job, JOB_STATUS_READY);
 875     job_event_ready(job);
 876 }
 877
 878 static void job_completed_txn_success(Job *job)
 879 {
 880     JobTxn *txn = job->txn;
 881     Job *other_job;
 882
 883     job_state_transition(job, JOB_STATUS_WAITING);
 884
 885     /*
 886      * Successful completion, see if there are other running jobs in this
 887      * txn.
 888      */
 889     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 890         if (!job_is_completed(other_job)) {
 891             return;
 892         }
 893         assert(other_job->ret == 0);
 894     }
 895
 896     job_txn_apply(job, job_transition_to_pending);
 897
 898     /* If no jobs need manual finalization, automatically do so */
 899     if (job_txn_apply(job, job_needs_finalize) == 0) {
 900         job_do_finalize(job);
 901     }
 902 }
 903
 904 static void job_completed(Job *job)
 905 {
 906     assert(job && job->txn && !job_is_completed(job));
 907
 908     job_update_rc(job);
 909     trace_job_completed(job, job->ret);
 910     if (job->ret) {
 911         job_completed_txn_abort(job);
 912     } else {
 913         job_completed_txn_success(job);
 914     }
 915 }
 916
 917 /** Useful only as a type shim for aio_bh_schedule_oneshot. */
 918 static void job_exit(void *opaque)
 919 {
 920     Job *job = (Job *)opaque;
 921     AioContext *ctx;
 922
 923     job_ref(job);
 924     aio_context_acquire(job->aio_context);
 925
 926     /* This is a lie, we're not quiescent, but still doing the completion
 927      * callbacks. However, completion callbacks tend to involve operations that
 928      * drain block nodes, and if .drained_poll still returned true, we would
 929      * deadlock. */
 930     job->busy = false;
 931     job_event_idle(job);
 932
 933     job_completed(job);
 934
 935     /*
 936      * Note that calling job_completed can move the job to a different
 937      * aio_context, so we cannot cache from above. job_txn_apply takes care of
 938      * acquiring the new lock, and we ref/unref to avoid job_completed freeing
 939      * the job underneath us.
 940      */
 941     ctx = job->aio_context;
 942     job_unref(job);
 943     aio_context_release(ctx);
 944 }
 945
 946 /**
 947  * All jobs must allow a pause point before entering their job proper. This
 948  * ensures that jobs can be paused prior to being started, then resumed later.
 949  */
 950 static void coroutine_fn job_co_entry(void *opaque)
 951 {
 952     Job *job = opaque;
 953
 954     assert(job && job->driver && job->driver->run);
 955     job_pause_point(job);
 956     job->ret = job->driver->run(job, &job->err);
 957     job->deferred_to_main_loop = true;
 958     job->busy = true;
 959     aio_bh_schedule_oneshot(qemu_get_aio_context(), job_exit, job);
 960 }
 961
 962 void job_start(Job *job)
 963 {
 964     assert(job && !job_started(job) && job->paused &&
 965            job->driver && job->driver->run);
 966     job->co = qemu_coroutine_create(job_co_entry, job);
 967     job->pause_count--;
 968     job->busy = true;
 969     job->paused = false;
 970     job_state_transition(job, JOB_STATUS_RUNNING);
 971     aio_co_enter(job->aio_context, job->co);
 972 }
 973
 974 void job_cancel(Job *job, bool force)
 975 {
 976     if (job->status == JOB_STATUS_CONCLUDED) {
 977         job_do_dismiss(job);
 978         return;
 979     }
 980     job_cancel_async(job, force);
 981     if (!job_started(job)) {
 982         job_completed(job);
 983     } else if (job->deferred_to_main_loop) {
 984         /*
 985          * job_cancel_async() ignores soft-cancel requests for jobs
 986          * that are already done (i.e. deferred to the main loop).  We
 987          * have to check again whether the job is really cancelled.
 988          * (job_cancel_requested() and job_is_cancelled() are equivalent
 989          * here, because job_cancel_async() will make soft-cancel
 990          * requests no-ops when deferred_to_main_loop is true.  We
 991          * choose to call job_is_cancelled() to show that we invoke
 992          * job_completed_txn_abort() only for force-cancelled jobs.)
 993          */
 994         if (job_is_cancelled(job)) {
 995             job_completed_txn_abort(job);
 996         }
 997     } else {
 998         job_enter(job);
 999     }
1000 }
1001
1002 void job_user_cancel(Job *job, bool force, Error **errp)
1003 {
1004     if (job_apply_verb(job, JOB_VERB_CANCEL, errp)) {
1005         return;
1006     }
1007     job_cancel(job, force);
1008 }
1009
1010 /* A wrapper around job_cancel() taking an Error ** parameter so it may be
1011  * used with job_finish_sync() without the need for (rather nasty) function
1012  * pointer casts there. */
1013 static void job_cancel_err(Job *job, Error **errp)
1014 {
1015     job_cancel(job, false);
1016 }
1017
1018 /**
1019  * Same as job_cancel_err(), but force-cancel.
1020  */
1021 static void job_force_cancel_err(Job *job, Error **errp)
1022 {
1023     job_cancel(job, true);
1024 }
1025
1026 int job_cancel_sync(Job *job, bool force)
1027 {
1028     if (force) {
1029         return job_finish_sync(job, &job_force_cancel_err, NULL);
1030     } else {
1031         return job_finish_sync(job, &job_cancel_err, NULL);
1032     }
1033 }
1034
1035 void job_cancel_sync_all(void)
1036 {
1037     Job *job;
1038     AioContext *aio_context;
1039
1040     while ((job = job_next(NULL))) {
1041         aio_context = job->aio_context;
1042         aio_context_acquire(aio_context);
1043         job_cancel_sync(job, true);
1044         aio_context_release(aio_context);
1045     }
1046 }
1047
1048 int job_complete_sync(Job *job, Error **errp)
1049 {
1050     return job_finish_sync(job, job_complete, errp);
1051 }
1052
1053 void job_complete(Job *job, Error **errp)
1054 {
1055     /* Should not be reachable via external interface for internal jobs */
1056     assert(job->id);
1057     if (job_apply_verb(job, JOB_VERB_COMPLETE, errp)) {
1058         return;
1059     }
1060     if (job_cancel_requested(job) || !job->driver->complete) {
1061         error_setg(errp, "The active block job '%s' cannot be completed",
1062                    job->id);
1063         return;
1064     }
1065
1066     job->driver->complete(job, errp);
1067 }
1068
1069 int job_finish_sync(Job *job, void (*finish)(Job *, Error **errp), Error **errp)
1070 {
1071     Error *local_err = NULL;
1072     int ret;
1073
1074     job_ref(job);
1075
1076     if (finish) {
1077         finish(job, &local_err);
1078     }
1079     if (local_err) {
1080         error_propagate(errp, local_err);
1081         job_unref(job);
1082         return -EBUSY;
1083     }
1084
1085     AIO_WAIT_WHILE(job->aio_context,
1086                    (job_enter(job), !job_is_completed(job)));
1087
1088     ret = (job_is_cancelled(job) && job->ret == 0) ? -ECANCELED : job->ret;
1089     job_unref(job);
1090     return ret;
1091 }