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     GLOBAL_STATE_CODE();
 385
 386     if (--job->refcnt == 0) {
 387         assert(job->status == JOB_STATUS_NULL);
 388         assert(!timer_pending(&job->sleep_timer));
 389         assert(!job->txn);
 390
 391         if (job->driver->free) {
 392             job->driver->free(job);
 393         }
 394
 395         QLIST_REMOVE(job, job_list);
 396
 397         progress_destroy(&job->progress);
 398         error_free(job->err);
 399         g_free(job->id);
 400         g_free(job);
 401     }
 402 }
 403
 404 void job_progress_update(Job *job, uint64_t done)
 405 {
 406     progress_work_done(&job->progress, done);
 407 }
 408
 409 void job_progress_set_remaining(Job *job, uint64_t remaining)
 410 {
 411     progress_set_remaining(&job->progress, remaining);
 412 }
 413
 414 void job_progress_increase_remaining(Job *job, uint64_t delta)
 415 {
 416     progress_increase_remaining(&job->progress, delta);
 417 }
 418
 419 void job_event_cancelled(Job *job)
 420 {
 421     notifier_list_notify(&job->on_finalize_cancelled, job);
 422 }
 423
 424 void job_event_completed(Job *job)
 425 {
 426     notifier_list_notify(&job->on_finalize_completed, job);
 427 }
 428
 429 static void job_event_pending(Job *job)
 430 {
 431     notifier_list_notify(&job->on_pending, job);
 432 }
 433
 434 static void job_event_ready(Job *job)
 435 {
 436     notifier_list_notify(&job->on_ready, job);
 437 }
 438
 439 static void job_event_idle(Job *job)
 440 {
 441     notifier_list_notify(&job->on_idle, job);
 442 }
 443
 444 void job_enter_cond(Job *job, bool(*fn)(Job *job))
 445 {
 446     if (!job_started(job)) {
 447         return;
 448     }
 449     if (job->deferred_to_main_loop) {
 450         return;
 451     }
 452
 453     job_lock();
 454     if (job->busy) {
 455         job_unlock();
 456         return;
 457     }
 458
 459     if (fn && !fn(job)) {
 460         job_unlock();
 461         return;
 462     }
 463
 464     assert(!job->deferred_to_main_loop);
 465     timer_del(&job->sleep_timer);
 466     job->busy = true;
 467     job_unlock();
 468     aio_co_enter(job->aio_context, job->co);
 469 }
 470
 471 void job_enter(Job *job)
 472 {
 473     job_enter_cond(job, NULL);
 474 }
 475
 476 /* Yield, and schedule a timer to reenter the coroutine after @ns nanoseconds.
 477  * Reentering the job coroutine with job_enter() before the timer has expired
 478  * is allowed and cancels the timer.
 479  *
 480  * If @ns is (uint64_t) -1, no timer is scheduled and job_enter() must be
 481  * called explicitly. */
 482 static void coroutine_fn job_do_yield(Job *job, uint64_t ns)
 483 {
 484     job_lock();
 485     if (ns != -1) {
 486         timer_mod(&job->sleep_timer, ns);
 487     }
 488     job->busy = false;
 489     job_event_idle(job);
 490     job_unlock();
 491     qemu_coroutine_yield();
 492
 493     /* Set by job_enter_cond() before re-entering the coroutine.  */
 494     assert(job->busy);
 495 }
 496
 497 void coroutine_fn job_pause_point(Job *job)
 498 {
 499     assert(job && job_started(job));
 500
 501     if (!job_should_pause(job)) {
 502         return;
 503     }
 504     if (job_is_cancelled(job)) {
 505         return;
 506     }
 507
 508     if (job->driver->pause) {
 509         job->driver->pause(job);
 510     }
 511
 512     if (job_should_pause(job) && !job_is_cancelled(job)) {
 513         JobStatus status = job->status;
 514         job_state_transition(job, status == JOB_STATUS_READY
 515                                   ? JOB_STATUS_STANDBY
 516                                   : JOB_STATUS_PAUSED);
 517         job->paused = true;
 518         job_do_yield(job, -1);
 519         job->paused = false;
 520         job_state_transition(job, status);
 521     }
 522
 523     if (job->driver->resume) {
 524         job->driver->resume(job);
 525     }
 526 }
 527
 528 void job_yield(Job *job)
 529 {
 530     assert(job->busy);
 531
 532     /* Check cancellation *before* setting busy = false, too!  */
 533     if (job_is_cancelled(job)) {
 534         return;
 535     }
 536
 537     if (!job_should_pause(job)) {
 538         job_do_yield(job, -1);
 539     }
 540
 541     job_pause_point(job);
 542 }
 543
 544 void coroutine_fn job_sleep_ns(Job *job, int64_t ns)
 545 {
 546     assert(job->busy);
 547
 548     /* Check cancellation *before* setting busy = false, too!  */
 549     if (job_is_cancelled(job)) {
 550         return;
 551     }
 552
 553     if (!job_should_pause(job)) {
 554         job_do_yield(job, qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + ns);
 555     }
 556
 557     job_pause_point(job);
 558 }
 559
 560 /* Assumes the block_job_mutex is held */
 561 static bool job_timer_not_pending(Job *job)
 562 {
 563     return !timer_pending(&job->sleep_timer);
 564 }
 565
 566 void job_pause(Job *job)
 567 {
 568     job->pause_count++;
 569     if (!job->paused) {
 570         job_enter(job);
 571     }
 572 }
 573
 574 void job_resume(Job *job)
 575 {
 576     assert(job->pause_count > 0);
 577     job->pause_count--;
 578     if (job->pause_count) {
 579         return;
 580     }
 581
 582     /* kick only if no timer is pending */
 583     job_enter_cond(job, job_timer_not_pending);
 584 }
 585
 586 void job_user_pause(Job *job, Error **errp)
 587 {
 588     if (job_apply_verb(job, JOB_VERB_PAUSE, errp)) {
 589         return;
 590     }
 591     if (job->user_paused) {
 592         error_setg(errp, "Job is already paused");
 593         return;
 594     }
 595     job->user_paused = true;
 596     job_pause(job);
 597 }
 598
 599 bool job_user_paused(Job *job)
 600 {
 601     return job->user_paused;
 602 }
 603
 604 void job_user_resume(Job *job, Error **errp)
 605 {
 606     assert(job);
 607     GLOBAL_STATE_CODE();
 608     if (!job->user_paused || job->pause_count <= 0) {
 609         error_setg(errp, "Can't resume a job that was not paused");
 610         return;
 611     }
 612     if (job_apply_verb(job, JOB_VERB_RESUME, errp)) {
 613         return;
 614     }
 615     if (job->driver->user_resume) {
 616         job->driver->user_resume(job);
 617     }
 618     job->user_paused = false;
 619     job_resume(job);
 620 }
 621
 622 static void job_do_dismiss(Job *job)
 623 {
 624     assert(job);
 625     job->busy = false;
 626     job->paused = false;
 627     job->deferred_to_main_loop = true;
 628
 629     job_txn_del_job(job);
 630
 631     job_state_transition(job, JOB_STATUS_NULL);
 632     job_unref(job);
 633 }
 634
 635 void job_dismiss(Job **jobptr, Error **errp)
 636 {
 637     Job *job = *jobptr;
 638     /* similarly to _complete, this is QMP-interface only. */
 639     assert(job->id);
 640     if (job_apply_verb(job, JOB_VERB_DISMISS, errp)) {
 641         return;
 642     }
 643
 644     job_do_dismiss(job);
 645     *jobptr = NULL;
 646 }
 647
 648 void job_early_fail(Job *job)
 649 {
 650     assert(job->status == JOB_STATUS_CREATED);
 651     job_do_dismiss(job);
 652 }
 653
 654 static void job_conclude(Job *job)
 655 {
 656     job_state_transition(job, JOB_STATUS_CONCLUDED);
 657     if (job->auto_dismiss || !job_started(job)) {
 658         job_do_dismiss(job);
 659     }
 660 }
 661
 662 static void job_update_rc(Job *job)
 663 {
 664     if (!job->ret && job_is_cancelled(job)) {
 665         job->ret = -ECANCELED;
 666     }
 667     if (job->ret) {
 668         if (!job->err) {
 669             error_setg(&job->err, "%s", strerror(-job->ret));
 670         }
 671         job_state_transition(job, JOB_STATUS_ABORTING);
 672     }
 673 }
 674
 675 static void job_commit(Job *job)
 676 {
 677     assert(!job->ret);
 678     GLOBAL_STATE_CODE();
 679     if (job->driver->commit) {
 680         job->driver->commit(job);
 681     }
 682 }
 683
 684 static void job_abort(Job *job)
 685 {
 686     assert(job->ret);
 687     GLOBAL_STATE_CODE();
 688     if (job->driver->abort) {
 689         job->driver->abort(job);
 690     }
 691 }
 692
 693 static void job_clean(Job *job)
 694 {
 695     GLOBAL_STATE_CODE();
 696     if (job->driver->clean) {
 697         job->driver->clean(job);
 698     }
 699 }
 700
 701 static int job_finalize_single(Job *job)
 702 {
 703     assert(job_is_completed(job));
 704
 705     /* Ensure abort is called for late-transactional failures */
 706     job_update_rc(job);
 707
 708     if (!job->ret) {
 709         job_commit(job);
 710     } else {
 711         job_abort(job);
 712     }
 713     job_clean(job);
 714
 715     if (job->cb) {
 716         job->cb(job->opaque, job->ret);
 717     }
 718
 719     /* Emit events only if we actually started */
 720     if (job_started(job)) {
 721         if (job_is_cancelled(job)) {
 722             job_event_cancelled(job);
 723         } else {
 724             job_event_completed(job);
 725         }
 726     }
 727
 728     job_txn_del_job(job);
 729     job_conclude(job);
 730     return 0;
 731 }
 732
 733 static void job_cancel_async(Job *job, bool force)
 734 {
 735     GLOBAL_STATE_CODE();
 736     if (job->driver->cancel) {
 737         force = job->driver->cancel(job, force);
 738     } else {
 739         /* No .cancel() means the job will behave as if force-cancelled */
 740         force = true;
 741     }
 742
 743     if (job->user_paused) {
 744         /* Do not call job_enter here, the caller will handle it.  */
 745         if (job->driver->user_resume) {
 746             job->driver->user_resume(job);
 747         }
 748         job->user_paused = false;
 749         assert(job->pause_count > 0);
 750         job->pause_count--;
 751     }
 752
 753     /*
 754      * Ignore soft cancel requests after the job is already done
 755      * (We will still invoke job->driver->cancel() above, but if the
 756      * job driver supports soft cancelling and the job is done, that
 757      * should be a no-op, too.  We still call it so it can override
 758      * @force.)
 759      */
 760     if (force || !job->deferred_to_main_loop) {
 761         job->cancelled = true;
 762         /* To prevent 'force == false' overriding a previous 'force == true' */
 763         job->force_cancel |= force;
 764     }
 765 }
 766
 767 static void job_completed_txn_abort(Job *job)
 768 {
 769     AioContext *ctx;
 770     JobTxn *txn = job->txn;
 771     Job *other_job;
 772
 773     if (txn->aborting) {
 774         /*
 775          * We are cancelled by another job, which will handle everything.
 776          */
 777         return;
 778     }
 779     txn->aborting = true;
 780     job_txn_ref(txn);
 781
 782     /*
 783      * We can only hold the single job's AioContext lock while calling
 784      * job_finalize_single() because the finalization callbacks can involve
 785      * calls of AIO_WAIT_WHILE(), which could deadlock otherwise.
 786      * Note that the job's AioContext may change when it is finalized.
 787      */
 788     job_ref(job);
 789     aio_context_release(job->aio_context);
 790
 791     /* Other jobs are effectively cancelled by us, set the status for
 792      * them; this job, however, may or may not be cancelled, depending
 793      * on the caller, so leave it. */
 794     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 795         if (other_job != job) {
 796             ctx = other_job->aio_context;
 797             aio_context_acquire(ctx);
 798             /*
 799              * This is a transaction: If one job failed, no result will matter.
 800              * Therefore, pass force=true to terminate all other jobs as quickly
 801              * as possible.
 802              */
 803             job_cancel_async(other_job, true);
 804             aio_context_release(ctx);
 805         }
 806     }
 807     while (!QLIST_EMPTY(&txn->jobs)) {
 808         other_job = QLIST_FIRST(&txn->jobs);
 809         /*
 810          * The job's AioContext may change, so store it in @ctx so we
 811          * release the same context that we have acquired before.
 812          */
 813         ctx = other_job->aio_context;
 814         aio_context_acquire(ctx);
 815         if (!job_is_completed(other_job)) {
 816             assert(job_cancel_requested(other_job));
 817             job_finish_sync(other_job, NULL, NULL);
 818         }
 819         job_finalize_single(other_job);
 820         aio_context_release(ctx);
 821     }
 822
 823     /*
 824      * Use job_ref()/job_unref() so we can read the AioContext here
 825      * even if the job went away during job_finalize_single().
 826      */
 827     aio_context_acquire(job->aio_context);
 828     job_unref(job);
 829
 830     job_txn_unref(txn);
 831 }
 832
 833 static int job_prepare(Job *job)
 834 {
 835     GLOBAL_STATE_CODE();
 836     if (job->ret == 0 && job->driver->prepare) {
 837         job->ret = job->driver->prepare(job);
 838         job_update_rc(job);
 839     }
 840     return job->ret;
 841 }
 842
 843 static int job_needs_finalize(Job *job)
 844 {
 845     return !job->auto_finalize;
 846 }
 847
 848 static void job_do_finalize(Job *job)
 849 {
 850     int rc;
 851     assert(job && job->txn);
 852
 853     /* prepare the transaction to complete */
 854     rc = job_txn_apply(job, job_prepare);
 855     if (rc) {
 856         job_completed_txn_abort(job);
 857     } else {
 858         job_txn_apply(job, job_finalize_single);
 859     }
 860 }
 861
 862 void job_finalize(Job *job, Error **errp)
 863 {
 864     assert(job && job->id);
 865     if (job_apply_verb(job, JOB_VERB_FINALIZE, errp)) {
 866         return;
 867     }
 868     job_do_finalize(job);
 869 }
 870
 871 static int job_transition_to_pending(Job *job)
 872 {
 873     job_state_transition(job, JOB_STATUS_PENDING);
 874     if (!job->auto_finalize) {
 875         job_event_pending(job);
 876     }
 877     return 0;
 878 }
 879
 880 void job_transition_to_ready(Job *job)
 881 {
 882     job_state_transition(job, JOB_STATUS_READY);
 883     job_event_ready(job);
 884 }
 885
 886 static void job_completed_txn_success(Job *job)
 887 {
 888     JobTxn *txn = job->txn;
 889     Job *other_job;
 890
 891     job_state_transition(job, JOB_STATUS_WAITING);
 892
 893     /*
 894      * Successful completion, see if there are other running jobs in this
 895      * txn.
 896      */
 897     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
 898         if (!job_is_completed(other_job)) {
 899             return;
 900         }
 901         assert(other_job->ret == 0);
 902     }
 903
 904     job_txn_apply(job, job_transition_to_pending);
 905
 906     /* If no jobs need manual finalization, automatically do so */
 907     if (job_txn_apply(job, job_needs_finalize) == 0) {
 908         job_do_finalize(job);
 909     }
 910 }
 911
 912 static void job_completed(Job *job)
 913 {
 914     assert(job && job->txn && !job_is_completed(job));
 915
 916     job_update_rc(job);
 917     trace_job_completed(job, job->ret);
 918     if (job->ret) {
 919         job_completed_txn_abort(job);
 920     } else {
 921         job_completed_txn_success(job);
 922     }
 923 }
 924
 925 /** Useful only as a type shim for aio_bh_schedule_oneshot. */
 926 static void job_exit(void *opaque)
 927 {
 928     Job *job = (Job *)opaque;
 929     AioContext *ctx;
 930
 931     job_ref(job);
 932     aio_context_acquire(job->aio_context);
 933
 934     /* This is a lie, we're not quiescent, but still doing the completion
 935      * callbacks. However, completion callbacks tend to involve operations that
 936      * drain block nodes, and if .drained_poll still returned true, we would
 937      * deadlock. */
 938     job->busy = false;
 939     job_event_idle(job);
 940
 941     job_completed(job);
 942
 943     /*
 944      * Note that calling job_completed can move the job to a different
 945      * aio_context, so we cannot cache from above. job_txn_apply takes care of
 946      * acquiring the new lock, and we ref/unref to avoid job_completed freeing
 947      * the job underneath us.
 948      */
 949     ctx = job->aio_context;
 950     job_unref(job);
 951     aio_context_release(ctx);
 952 }
 953
 954 /**
 955  * All jobs must allow a pause point before entering their job proper. This
 956  * ensures that jobs can be paused prior to being started, then resumed later.
 957  */
 958 static void coroutine_fn job_co_entry(void *opaque)
 959 {
 960     Job *job = opaque;
 961
 962     assert(job && job->driver && job->driver->run);
 963     assert(job->aio_context == qemu_get_current_aio_context());
 964     job_pause_point(job);
 965     job->ret = job->driver->run(job, &job->err);
 966     job->deferred_to_main_loop = true;
 967     job->busy = true;
 968     aio_bh_schedule_oneshot(qemu_get_aio_context(), job_exit, job);
 969 }
 970
 971 void job_start(Job *job)
 972 {
 973     assert(job && !job_started(job) && job->paused &&
 974            job->driver && job->driver->run);
 975     job->co = qemu_coroutine_create(job_co_entry, job);
 976     job->pause_count--;
 977     job->busy = true;
 978     job->paused = false;
 979     job_state_transition(job, JOB_STATUS_RUNNING);
 980     aio_co_enter(job->aio_context, job->co);
 981 }
 982
 983 void job_cancel(Job *job, bool force)
 984 {
 985     if (job->status == JOB_STATUS_CONCLUDED) {
 986         job_do_dismiss(job);
 987         return;
 988     }
 989     job_cancel_async(job, force);
 990     if (!job_started(job)) {
 991         job_completed(job);
 992     } else if (job->deferred_to_main_loop) {
 993         /*
 994          * job_cancel_async() ignores soft-cancel requests for jobs
 995          * that are already done (i.e. deferred to the main loop).  We
 996          * have to check again whether the job is really cancelled.
 997          * (job_cancel_requested() and job_is_cancelled() are equivalent
 998          * here, because job_cancel_async() will make soft-cancel
 999          * requests no-ops when deferred_to_main_loop is true.  We
1000          * choose to call job_is_cancelled() to show that we invoke
1001          * job_completed_txn_abort() only for force-cancelled jobs.)
1002          */
1003         if (job_is_cancelled(job)) {
1004             job_completed_txn_abort(job);
1005         }
1006     } else {
1007         job_enter(job);
1008     }
1009 }
1010
1011 void job_user_cancel(Job *job, bool force, Error **errp)
1012 {
1013     if (job_apply_verb(job, JOB_VERB_CANCEL, errp)) {
1014         return;
1015     }
1016     job_cancel(job, force);
1017 }
1018
1019 /* A wrapper around job_cancel() taking an Error ** parameter so it may be
1020  * used with job_finish_sync() without the need for (rather nasty) function
1021  * pointer casts there. */
1022 static void job_cancel_err(Job *job, Error **errp)
1023 {
1024     job_cancel(job, false);
1025 }
1026
1027 /**
1028  * Same as job_cancel_err(), but force-cancel.
1029  */
1030 static void job_force_cancel_err(Job *job, Error **errp)
1031 {
1032     job_cancel(job, true);
1033 }
1034
1035 int job_cancel_sync(Job *job, bool force)
1036 {
1037     if (force) {
1038         return job_finish_sync(job, &job_force_cancel_err, NULL);
1039     } else {
1040         return job_finish_sync(job, &job_cancel_err, NULL);
1041     }
1042 }
1043
1044 void job_cancel_sync_all(void)
1045 {
1046     Job *job;
1047     AioContext *aio_context;
1048
1049     while ((job = job_next(NULL))) {
1050         aio_context = job->aio_context;
1051         aio_context_acquire(aio_context);
1052         job_cancel_sync(job, true);
1053         aio_context_release(aio_context);
1054     }
1055 }
1056
1057 int job_complete_sync(Job *job, Error **errp)
1058 {
1059     return job_finish_sync(job, job_complete, errp);
1060 }
1061
1062 void job_complete(Job *job, Error **errp)
1063 {
1064     /* Should not be reachable via external interface for internal jobs */
1065     assert(job->id);
1066     GLOBAL_STATE_CODE();
1067     if (job_apply_verb(job, JOB_VERB_COMPLETE, errp)) {
1068         return;
1069     }
1070     if (job_cancel_requested(job) || !job->driver->complete) {
1071         error_setg(errp, "The active block job '%s' cannot be completed",
1072                    job->id);
1073         return;
1074     }
1075
1076     job->driver->complete(job, errp);
1077 }
1078
1079 int job_finish_sync(Job *job, void (*finish)(Job *, Error **errp), Error **errp)
1080 {
1081     Error *local_err = NULL;
1082     int ret;
1083
1084     job_ref(job);
1085
1086     if (finish) {
1087         finish(job, &local_err);
1088     }
1089     if (local_err) {
1090         error_propagate(errp, local_err);
1091         job_unref(job);
1092         return -EBUSY;
1093     }
1094
1095     AIO_WAIT_WHILE(job->aio_context,
1096                    (job_enter(job), !job_is_completed(job)));
1097
1098     ret = (job_is_cancelled(job) && job->ret == 0) ? -ECANCELED : job->ret;
1099     job_unref(job);
1100     return ret;
1101 }