qemu

job.c (33068B)

---

 /*
  * Background jobs (long-running operations)
  *
  * Copyright (c) 2011 IBM Corp.
  * Copyright (c) 2012, 2018 Red Hat, Inc.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
 
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "qemu/job.h"
 #include "qemu/id.h"
 #include "qemu/main-loop.h"
 #include "block/aio-wait.h"
 #include "trace/trace-root.h"
 #include "qapi/qapi-events-job.h"
 
 /*
  * The job API is composed of two categories of functions.
  *
  * The first includes functions used by the monitor.  The monitor is
  * peculiar in that it accesses the job list with job_get, and
  * therefore needs consistency across job_get and the actual operation
  * (e.g. job_user_cancel). To achieve this consistency, the caller
  * calls job_lock/job_unlock itself around the whole operation.
  *
  *
  * The second includes functions used by the job drivers and sometimes
  * by the core block layer. These delegate the locking to the callee instead.
  */
 
 /*
  * job_mutex protects the jobs list, but also makes the
  * struct job fields thread-safe.
  */
 QemuMutex job_mutex;
 
 /* Protected by job_mutex */
 static QLIST_HEAD(, Job) jobs = QLIST_HEAD_INITIALIZER(jobs);
 
 /* Job State Transition Table */
 bool JobSTT[JOB_STATUS__MAX][JOB_STATUS__MAX] = {
                                     /* U, C, R, P, Y, S, W, D, X, E, N */
     /* U: */ [JOB_STATUS_UNDEFINED] = {0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0},
     /* C: */ [JOB_STATUS_CREATED]   = {0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1},
     /* R: */ [JOB_STATUS_RUNNING]   = {0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0},
     /* P: */ [JOB_STATUS_PAUSED]    = {0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0},
     /* Y: */ [JOB_STATUS_READY]     = {0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0},
     /* S: */ [JOB_STATUS_STANDBY]   = {0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0},
     /* W: */ [JOB_STATUS_WAITING]   = {0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0},
     /* D: */ [JOB_STATUS_PENDING]   = {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0},
     /* X: */ [JOB_STATUS_ABORTING]  = {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0},
     /* E: */ [JOB_STATUS_CONCLUDED] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1},
     /* N: */ [JOB_STATUS_NULL]      = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
 };
 
 bool JobVerbTable[JOB_VERB__MAX][JOB_STATUS__MAX] = {
                                     /* U, C, R, P, Y, S, W, D, X, E, N */
     [JOB_VERB_CANCEL]               = {0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0},
     [JOB_VERB_PAUSE]                = {0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0},
     [JOB_VERB_RESUME]               = {0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0},
     [JOB_VERB_SET_SPEED]            = {0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0},
     [JOB_VERB_COMPLETE]             = {0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0},
     [JOB_VERB_FINALIZE]             = {0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0},
     [JOB_VERB_DISMISS]              = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0},
 };
 
 /* Transactional group of jobs */
 struct JobTxn {
 
     /* Is this txn being cancelled? */
     bool aborting;
 
     /* List of jobs */
     QLIST_HEAD(, Job) jobs;
 
     /* Reference count */
     int refcnt;
 };
 
 void job_lock(void)
 {
     qemu_mutex_lock(&job_mutex);
 }
 
 void job_unlock(void)
 {
     qemu_mutex_unlock(&job_mutex);
 }
 
 static void __attribute__((__constructor__)) job_init(void)
 {
     qemu_mutex_init(&job_mutex);
 }
 
 JobTxn *job_txn_new(void)
 {
     JobTxn *txn = g_new0(JobTxn, 1);
     QLIST_INIT(&txn->jobs);
     txn->refcnt = 1;
     return txn;
 }
 
 /* Called with job_mutex held. */
 static void job_txn_ref_locked(JobTxn *txn)
 {
     txn->refcnt++;
 }
 
 void job_txn_unref_locked(JobTxn *txn)
 {
     if (txn && --txn->refcnt == 0) {
         g_free(txn);
     }
 }
 
 void job_txn_unref(JobTxn *txn)
 {
     JOB_LOCK_GUARD();
     job_txn_unref_locked(txn);
 }
 
 /**
  * @txn: The transaction (may be NULL)
  * @job: Job to add to the transaction
  *
  * Add @job to the transaction.  The @job must not already be in a transaction.
  * The caller must call either job_txn_unref() or job_completed() to release
  * the reference that is automatically grabbed here.
  *
  * If @txn is NULL, the function does nothing.
  *
  * Called with job_mutex held.
  */
 static void job_txn_add_job_locked(JobTxn *txn, Job *job)
 {
     if (!txn) {
         return;
     }
 
     assert(!job->txn);
     job->txn = txn;
 
     QLIST_INSERT_HEAD(&txn->jobs, job, txn_list);
     job_txn_ref_locked(txn);
 }
 
 /* Called with job_mutex held. */
 static void job_txn_del_job_locked(Job *job)
 {
     if (job->txn) {
         QLIST_REMOVE(job, txn_list);
         job_txn_unref_locked(job->txn);
         job->txn = NULL;
     }
 }
 
 /* Called with job_mutex held, but releases it temporarily. */
 static int job_txn_apply_locked(Job *job, int fn(Job *))
 {
     Job *other_job, *next;
     JobTxn *txn = job->txn;
     int rc = 0;
 
     /*
      * Similar to job_completed_txn_abort, we take each job's lock before
      * applying fn, but since we assume that outer_ctx is held by the caller,
      * we need to release it here to avoid holding the lock twice - which would
      * break AIO_WAIT_WHILE from within fn.
      */
     job_ref_locked(job);
 
     QLIST_FOREACH_SAFE(other_job, &txn->jobs, txn_list, next) {
         rc = fn(other_job);
         if (rc) {
             break;
         }
     }
 
     job_unref_locked(job);
     return rc;
 }
 
 bool job_is_internal(Job *job)
 {
     return (job->id == NULL);
 }
 
 /* Called with job_mutex held. */
 static void job_state_transition_locked(Job *job, JobStatus s1)
 {
     JobStatus s0 = job->status;
     assert(s1 >= 0 && s1 < JOB_STATUS__MAX);
     trace_job_state_transition(job, job->ret,
                                JobSTT[s0][s1] ? "allowed" : "disallowed",
                                JobStatus_str(s0), JobStatus_str(s1));
     assert(JobSTT[s0][s1]);
     job->status = s1;
 
     if (!job_is_internal(job) && s1 != s0) {
         qapi_event_send_job_status_change(job->id, job->status);
     }
 }
 
 int job_apply_verb_locked(Job *job, JobVerb verb, Error **errp)
 {
     JobStatus s0 = job->status;
     assert(verb >= 0 && verb < JOB_VERB__MAX);
     trace_job_apply_verb(job, JobStatus_str(s0), JobVerb_str(verb),
                          JobVerbTable[verb][s0] ? "allowed" : "prohibited");
     if (JobVerbTable[verb][s0]) {
         return 0;
     }
     error_setg(errp, "Job '%s' in state '%s' cannot accept command verb '%s'",
                job->id, JobStatus_str(s0), JobVerb_str(verb));
     return -EPERM;
 }
 
 JobType job_type(const Job *job)
 {
     return job->driver->job_type;
 }
 
 const char *job_type_str(const Job *job)
 {
     return JobType_str(job_type(job));
 }
 
 bool job_is_cancelled_locked(Job *job)
 {
     /* force_cancel may be true only if cancelled is true, too */
     assert(job->cancelled || !job->force_cancel);
     return job->force_cancel;
 }
 
 bool job_is_cancelled(Job *job)
 {
     JOB_LOCK_GUARD();
     return job_is_cancelled_locked(job);
 }
 
 /* Called with job_mutex held. */
 static bool job_cancel_requested_locked(Job *job)
 {
     return job->cancelled;
 }
 
 bool job_cancel_requested(Job *job)
 {
     JOB_LOCK_GUARD();
     return job_cancel_requested_locked(job);
 }
 
 bool job_is_ready_locked(Job *job)
 {
     switch (job->status) {
     case JOB_STATUS_UNDEFINED:
     case JOB_STATUS_CREATED:
     case JOB_STATUS_RUNNING:
     case JOB_STATUS_PAUSED:
     case JOB_STATUS_WAITING:
     case JOB_STATUS_PENDING:
     case JOB_STATUS_ABORTING:
     case JOB_STATUS_CONCLUDED:
     case JOB_STATUS_NULL:
         return false;
     case JOB_STATUS_READY:
     case JOB_STATUS_STANDBY:
         return true;
     default:
         g_assert_not_reached();
     }
     return false;
 }
 
 bool job_is_ready(Job *job)
 {
     JOB_LOCK_GUARD();
     return job_is_ready_locked(job);
 }
 
 bool job_is_completed_locked(Job *job)
 {
     switch (job->status) {
     case JOB_STATUS_UNDEFINED:
     case JOB_STATUS_CREATED:
     case JOB_STATUS_RUNNING:
     case JOB_STATUS_PAUSED:
     case JOB_STATUS_READY:
     case JOB_STATUS_STANDBY:
         return false;
     case JOB_STATUS_WAITING:
     case JOB_STATUS_PENDING:
     case JOB_STATUS_ABORTING:
     case JOB_STATUS_CONCLUDED:
     case JOB_STATUS_NULL:
         return true;
     default:
         g_assert_not_reached();
     }
     return false;
 }
 
 static bool job_is_completed(Job *job)
 {
     JOB_LOCK_GUARD();
     return job_is_completed_locked(job);
 }
 
 static bool job_started_locked(Job *job)
 {
     return job->co;
 }
 
 /* Called with job_mutex held. */
 static bool job_should_pause_locked(Job *job)
 {
     return job->pause_count > 0;
 }
 
 Job *job_next_locked(Job *job)
 {
     if (!job) {
         return QLIST_FIRST(&jobs);
     }
     return QLIST_NEXT(job, job_list);
 }
 
 Job *job_next(Job *job)
 {
     JOB_LOCK_GUARD();
     return job_next_locked(job);
 }
 
 Job *job_get_locked(const char *id)
 {
     Job *job;
 
     QLIST_FOREACH(job, &jobs, job_list) {
         if (job->id && !strcmp(id, job->id)) {
             return job;
         }
     }
 
     return NULL;
 }
 
 void job_set_aio_context(Job *job, AioContext *ctx)
 {
     /* protect against read in job_finish_sync_locked and job_start */
     GLOBAL_STATE_CODE();
     /* protect against read in job_do_yield_locked */
     JOB_LOCK_GUARD();
     /* ensure the job is quiescent while the AioContext is changed */
     assert(job->paused || job_is_completed_locked(job));
     job->aio_context = ctx;
 }
 
 /* Called with job_mutex *not* held. */
 static void job_sleep_timer_cb(void *opaque)
 {
     Job *job = opaque;
 
     job_enter(job);
 }
 
 void *job_create(const char *job_id, const JobDriver *driver, JobTxn *txn,
                  AioContext *ctx, int flags, BlockCompletionFunc *cb,
                  void *opaque, Error **errp)
 {
     Job *job;
 
     JOB_LOCK_GUARD();
 
     if (job_id) {
         if (flags & JOB_INTERNAL) {
             error_setg(errp, "Cannot specify job ID for internal job");
             return NULL;
         }
         if (!id_wellformed(job_id)) {
             error_setg(errp, "Invalid job ID '%s'", job_id);
             return NULL;
         }
         if (job_get_locked(job_id)) {
             error_setg(errp, "Job ID '%s' already in use", job_id);
             return NULL;
         }
     } else if (!(flags & JOB_INTERNAL)) {
         error_setg(errp, "An explicit job ID is required");
         return NULL;
     }
 
     job = g_malloc0(driver->instance_size);
     job->driver        = driver;
     job->id            = g_strdup(job_id);
     job->refcnt        = 1;
     job->aio_context   = ctx;
     job->busy          = false;
     job->paused        = true;
     job->pause_count   = 1;
     job->auto_finalize = !(flags & JOB_MANUAL_FINALIZE);
     job->auto_dismiss  = !(flags & JOB_MANUAL_DISMISS);
     job->cb            = cb;
     job->opaque        = opaque;
 
     progress_init(&job->progress);
 
     notifier_list_init(&job->on_finalize_cancelled);
     notifier_list_init(&job->on_finalize_completed);
     notifier_list_init(&job->on_pending);
     notifier_list_init(&job->on_ready);
     notifier_list_init(&job->on_idle);
 
     job_state_transition_locked(job, JOB_STATUS_CREATED);
     aio_timer_init(qemu_get_aio_context(), &job->sleep_timer,
                    QEMU_CLOCK_REALTIME, SCALE_NS,
                    job_sleep_timer_cb, job);
 
     QLIST_INSERT_HEAD(&jobs, job, job_list);
 
     /* Single jobs are modeled as single-job transactions for sake of
      * consolidating the job management logic */
     if (!txn) {
         txn = job_txn_new();
         job_txn_add_job_locked(txn, job);
         job_txn_unref_locked(txn);
     } else {
         job_txn_add_job_locked(txn, job);
     }
 
     return job;
 }
 
 void job_ref_locked(Job *job)
 {
     ++job->refcnt;
 }
 
 void job_unref_locked(Job *job)
 {
     GLOBAL_STATE_CODE();
 
     if (--job->refcnt == 0) {
         assert(job->status == JOB_STATUS_NULL);
         assert(!timer_pending(&job->sleep_timer));
         assert(!job->txn);
 
         if (job->driver->free) {
             AioContext *aio_context = job->aio_context;
             job_unlock();
             /* FIXME: aiocontext lock is required because cb calls blk_unref */
             aio_context_acquire(aio_context);
             job->driver->free(job);
             aio_context_release(aio_context);
             job_lock();
         }
 
         QLIST_REMOVE(job, job_list);
 
         progress_destroy(&job->progress);
         error_free(job->err);
         g_free(job->id);
         g_free(job);
     }
 }
 
 void job_progress_update(Job *job, uint64_t done)
 {
     progress_work_done(&job->progress, done);
 }
 
 void job_progress_set_remaining(Job *job, uint64_t remaining)
 {
     progress_set_remaining(&job->progress, remaining);
 }
 
 void job_progress_increase_remaining(Job *job, uint64_t delta)
 {
     progress_increase_remaining(&job->progress, delta);
 }
 
 /**
  * To be called when a cancelled job is finalised.
  * Called with job_mutex held.
  */
 static void job_event_cancelled_locked(Job *job)
 {
     notifier_list_notify(&job->on_finalize_cancelled, job);
 }
 
 /**
  * To be called when a successfully completed job is finalised.
  * Called with job_mutex held.
  */
 static void job_event_completed_locked(Job *job)
 {
     notifier_list_notify(&job->on_finalize_completed, job);
 }
 
 /* Called with job_mutex held. */
 static void job_event_pending_locked(Job *job)
 {
     notifier_list_notify(&job->on_pending, job);
 }
 
 /* Called with job_mutex held. */
 static void job_event_ready_locked(Job *job)
 {
     notifier_list_notify(&job->on_ready, job);
 }
 
 /* Called with job_mutex held. */
 static void job_event_idle_locked(Job *job)
 {
     notifier_list_notify(&job->on_idle, job);
 }
 
 void job_enter_cond_locked(Job *job, bool(*fn)(Job *job))
 {
     if (!job_started_locked(job)) {
         return;
     }
     if (job->deferred_to_main_loop) {
         return;
     }
 
     if (job->busy) {
         return;
     }
 
     if (fn && !fn(job)) {
         return;
     }
 
     assert(!job->deferred_to_main_loop);
     timer_del(&job->sleep_timer);
     job->busy = true;
     job_unlock();
     aio_co_wake(job->co);
     job_lock();
 }
 
 void job_enter(Job *job)
 {
     JOB_LOCK_GUARD();
     job_enter_cond_locked(job, NULL);
 }
 
 /* Yield, and schedule a timer to reenter the coroutine after @ns nanoseconds.
  * Reentering the job coroutine with job_enter() before the timer has expired
  * is allowed and cancels the timer.
  *
  * If @ns is (uint64_t) -1, no timer is scheduled and job_enter() must be
  * called explicitly.
  *
  * Called with job_mutex held, but releases it temporarily.
  */
 static void coroutine_fn job_do_yield_locked(Job *job, uint64_t ns)
 {
     AioContext *next_aio_context;
 
     if (ns != -1) {
         timer_mod(&job->sleep_timer, ns);
     }
     job->busy = false;
     job_event_idle_locked(job);
     job_unlock();
     qemu_coroutine_yield();
     job_lock();
 
     next_aio_context = job->aio_context;
     /*
      * Coroutine has resumed, but in the meanwhile the job AioContext
      * might have changed via bdrv_try_change_aio_context(), so we need to move
      * the coroutine too in the new aiocontext.
      */
     while (qemu_get_current_aio_context() != next_aio_context) {
         job_unlock();
         aio_co_reschedule_self(next_aio_context);
         job_lock();
         next_aio_context = job->aio_context;
     }
 
     /* Set by job_enter_cond_locked() before re-entering the coroutine.  */
     assert(job->busy);
 }
 
 /* Called with job_mutex held, but releases it temporarily. */
 static void coroutine_fn job_pause_point_locked(Job *job)
 {
     assert(job && job_started_locked(job));
 
     if (!job_should_pause_locked(job)) {
         return;
     }
     if (job_is_cancelled_locked(job)) {
         return;
     }
 
     if (job->driver->pause) {
         job_unlock();
         job->driver->pause(job);
         job_lock();
     }
 
     if (job_should_pause_locked(job) && !job_is_cancelled_locked(job)) {
         JobStatus status = job->status;
         job_state_transition_locked(job, status == JOB_STATUS_READY
                                     ? JOB_STATUS_STANDBY
                                     : JOB_STATUS_PAUSED);
         job->paused = true;
         job_do_yield_locked(job, -1);
         job->paused = false;
         job_state_transition_locked(job, status);
     }
 
     if (job->driver->resume) {
         job_unlock();
         job->driver->resume(job);
         job_lock();
     }
 }
 
 void coroutine_fn job_pause_point(Job *job)
 {
     JOB_LOCK_GUARD();
     job_pause_point_locked(job);
 }
 
 void coroutine_fn job_yield(Job *job)
 {
     JOB_LOCK_GUARD();
     assert(job->busy);
 
     /* Check cancellation *before* setting busy = false, too!  */
     if (job_is_cancelled_locked(job)) {
         return;
     }
 
     if (!job_should_pause_locked(job)) {
         job_do_yield_locked(job, -1);
     }
 
     job_pause_point_locked(job);
 }
 
 void coroutine_fn job_sleep_ns(Job *job, int64_t ns)
 {
     JOB_LOCK_GUARD();
     assert(job->busy);
 
     /* Check cancellation *before* setting busy = false, too!  */
     if (job_is_cancelled_locked(job)) {
         return;
     }
 
     if (!job_should_pause_locked(job)) {
         job_do_yield_locked(job, qemu_clock_get_ns(QEMU_CLOCK_REALTIME) + ns);
     }
 
     job_pause_point_locked(job);
 }
 
 /* Assumes the job_mutex is held */
 static bool job_timer_not_pending_locked(Job *job)
 {
     return !timer_pending(&job->sleep_timer);
 }
 
 void job_pause_locked(Job *job)
 {
     job->pause_count++;
     if (!job->paused) {
         job_enter_cond_locked(job, NULL);
     }
 }
 
 void job_pause(Job *job)
 {
     JOB_LOCK_GUARD();
     job_pause_locked(job);
 }
 
 void job_resume_locked(Job *job)
 {
     assert(job->pause_count > 0);
     job->pause_count--;
     if (job->pause_count) {
         return;
     }
 
     /* kick only if no timer is pending */
     job_enter_cond_locked(job, job_timer_not_pending_locked);
 }
 
 void job_resume(Job *job)
 {
     JOB_LOCK_GUARD();
     job_resume_locked(job);
 }
 
 void job_user_pause_locked(Job *job, Error **errp)
 {
     if (job_apply_verb_locked(job, JOB_VERB_PAUSE, errp)) {
         return;
     }
     if (job->user_paused) {
         error_setg(errp, "Job is already paused");
         return;
     }
     job->user_paused = true;
     job_pause_locked(job);
 }
 
 bool job_user_paused_locked(Job *job)
 {
     return job->user_paused;
 }
 
 void job_user_resume_locked(Job *job, Error **errp)
 {
     assert(job);
     GLOBAL_STATE_CODE();
     if (!job->user_paused || job->pause_count <= 0) {
         error_setg(errp, "Can't resume a job that was not paused");
         return;
     }
     if (job_apply_verb_locked(job, JOB_VERB_RESUME, errp)) {
         return;
     }
     if (job->driver->user_resume) {
         job_unlock();
         job->driver->user_resume(job);
         job_lock();
     }
     job->user_paused = false;
     job_resume_locked(job);
 }
 
 /* Called with job_mutex held, but releases it temporarily. */
 static void job_do_dismiss_locked(Job *job)
 {
     assert(job);
     job->busy = false;
     job->paused = false;
     job->deferred_to_main_loop = true;
 
     job_txn_del_job_locked(job);
 
     job_state_transition_locked(job, JOB_STATUS_NULL);
     job_unref_locked(job);
 }
 
 void job_dismiss_locked(Job **jobptr, Error **errp)
 {
     Job *job = *jobptr;
     /* similarly to _complete, this is QMP-interface only. */
     assert(job->id);
     if (job_apply_verb_locked(job, JOB_VERB_DISMISS, errp)) {
         return;
     }
 
     job_do_dismiss_locked(job);
     *jobptr = NULL;
 }
 
 void job_early_fail(Job *job)
 {
     JOB_LOCK_GUARD();
     assert(job->status == JOB_STATUS_CREATED);
     job_do_dismiss_locked(job);
 }
 
 /* Called with job_mutex held. */
 static void job_conclude_locked(Job *job)
 {
     job_state_transition_locked(job, JOB_STATUS_CONCLUDED);
     if (job->auto_dismiss || !job_started_locked(job)) {
         job_do_dismiss_locked(job);
     }
 }
 
 /* Called with job_mutex held. */
 static void job_update_rc_locked(Job *job)
 {
     if (!job->ret && job_is_cancelled_locked(job)) {
         job->ret = -ECANCELED;
     }
     if (job->ret) {
         if (!job->err) {
             error_setg(&job->err, "%s", strerror(-job->ret));
         }
         job_state_transition_locked(job, JOB_STATUS_ABORTING);
     }
 }
 
 static void job_commit(Job *job)
 {
     assert(!job->ret);
     GLOBAL_STATE_CODE();
     if (job->driver->commit) {
         job->driver->commit(job);
     }
 }
 
 static void job_abort(Job *job)
 {
     assert(job->ret);
     GLOBAL_STATE_CODE();
     if (job->driver->abort) {
         job->driver->abort(job);
     }
 }
 
 static void job_clean(Job *job)
 {
     GLOBAL_STATE_CODE();
     if (job->driver->clean) {
         job->driver->clean(job);
     }
 }
 
 /*
  * Called with job_mutex held, but releases it temporarily.
  * Takes AioContext lock internally to invoke a job->driver callback.
  */
 static int job_finalize_single_locked(Job *job)
 {
     int job_ret;
     AioContext *ctx = job->aio_context;
 
     assert(job_is_completed_locked(job));
 
     /* Ensure abort is called for late-transactional failures */
     job_update_rc_locked(job);
 
     job_ret = job->ret;
     job_unlock();
     aio_context_acquire(ctx);
 
     if (!job_ret) {
         job_commit(job);
     } else {
         job_abort(job);
     }
     job_clean(job);
 
     if (job->cb) {
         job->cb(job->opaque, job_ret);
     }
 
     aio_context_release(ctx);
     job_lock();
 
     /* Emit events only if we actually started */
     if (job_started_locked(job)) {
         if (job_is_cancelled_locked(job)) {
             job_event_cancelled_locked(job);
         } else {
             job_event_completed_locked(job);
         }
     }
 
     job_txn_del_job_locked(job);
     job_conclude_locked(job);
     return 0;
 }
 
 /*
  * Called with job_mutex held, but releases it temporarily.
  * Takes AioContext lock internally to invoke a job->driver callback.
  */
 static void job_cancel_async_locked(Job *job, bool force)
 {
     AioContext *ctx = job->aio_context;
     GLOBAL_STATE_CODE();
     if (job->driver->cancel) {
         job_unlock();
         aio_context_acquire(ctx);
         force = job->driver->cancel(job, force);
         aio_context_release(ctx);
         job_lock();
     } else {
         /* No .cancel() means the job will behave as if force-cancelled */
         force = true;
     }
 
     if (job->user_paused) {
         /* Do not call job_enter here, the caller will handle it.  */
         if (job->driver->user_resume) {
             job_unlock();
             job->driver->user_resume(job);
             job_lock();
         }
         job->user_paused = false;
         assert(job->pause_count > 0);
         job->pause_count--;
     }
 
     /*
      * Ignore soft cancel requests after the job is already done
      * (We will still invoke job->driver->cancel() above, but if the
      * job driver supports soft cancelling and the job is done, that
      * should be a no-op, too.  We still call it so it can override
      * @force.)
      */
     if (force || !job->deferred_to_main_loop) {
         job->cancelled = true;
         /* To prevent 'force == false' overriding a previous 'force == true' */
         job->force_cancel |= force;
     }
 }
 
 /*
  * Called with job_mutex held, but releases it temporarily.
  * Takes AioContext lock internally to invoke a job->driver callback.
  */
 static void job_completed_txn_abort_locked(Job *job)
 {
     JobTxn *txn = job->txn;
     Job *other_job;
 
     if (txn->aborting) {
         /*
          * We are cancelled by another job, which will handle everything.
          */
         return;
     }
     txn->aborting = true;
     job_txn_ref_locked(txn);
 
     job_ref_locked(job);
 
     /* Other jobs are effectively cancelled by us, set the status for
      * them; this job, however, may or may not be cancelled, depending
      * on the caller, so leave it. */
     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
         if (other_job != job) {
             /*
              * This is a transaction: If one job failed, no result will matter.
              * Therefore, pass force=true to terminate all other jobs as quickly
              * as possible.
              */
             job_cancel_async_locked(other_job, true);
         }
     }
     while (!QLIST_EMPTY(&txn->jobs)) {
         other_job = QLIST_FIRST(&txn->jobs);
         if (!job_is_completed_locked(other_job)) {
             assert(job_cancel_requested_locked(other_job));
             job_finish_sync_locked(other_job, NULL, NULL);
         }
         job_finalize_single_locked(other_job);
     }
 
     job_unref_locked(job);
     job_txn_unref_locked(txn);
 }
 
 /* Called with job_mutex held, but releases it temporarily */
 static int job_prepare_locked(Job *job)
 {
     int ret;
     AioContext *ctx = job->aio_context;
 
     GLOBAL_STATE_CODE();
 
     if (job->ret == 0 && job->driver->prepare) {
         job_unlock();
         aio_context_acquire(ctx);
         ret = job->driver->prepare(job);
         aio_context_release(ctx);
         job_lock();
         job->ret = ret;
         job_update_rc_locked(job);
     }
 
     return job->ret;
 }
 
 /* Called with job_mutex held */
 static int job_needs_finalize_locked(Job *job)
 {
     return !job->auto_finalize;
 }
 
 /* Called with job_mutex held */
 static void job_do_finalize_locked(Job *job)
 {
     int rc;
     assert(job && job->txn);
 
     /* prepare the transaction to complete */
     rc = job_txn_apply_locked(job, job_prepare_locked);
     if (rc) {
         job_completed_txn_abort_locked(job);
     } else {
         job_txn_apply_locked(job, job_finalize_single_locked);
     }
 }
 
 void job_finalize_locked(Job *job, Error **errp)
 {
     assert(job && job->id);
     if (job_apply_verb_locked(job, JOB_VERB_FINALIZE, errp)) {
         return;
     }
     job_do_finalize_locked(job);
 }
 
 /* Called with job_mutex held. */
 static int job_transition_to_pending_locked(Job *job)
 {
     job_state_transition_locked(job, JOB_STATUS_PENDING);
     if (!job->auto_finalize) {
         job_event_pending_locked(job);
     }
     return 0;
 }
 
 void job_transition_to_ready(Job *job)
 {
     JOB_LOCK_GUARD();
     job_state_transition_locked(job, JOB_STATUS_READY);
     job_event_ready_locked(job);
 }
 
 /* Called with job_mutex held. */
 static void job_completed_txn_success_locked(Job *job)
 {
     JobTxn *txn = job->txn;
     Job *other_job;
 
     job_state_transition_locked(job, JOB_STATUS_WAITING);
 
     /*
      * Successful completion, see if there are other running jobs in this
      * txn.
      */
     QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
         if (!job_is_completed_locked(other_job)) {
             return;
         }
         assert(other_job->ret == 0);
     }
 
     job_txn_apply_locked(job, job_transition_to_pending_locked);
 
     /* If no jobs need manual finalization, automatically do so */
     if (job_txn_apply_locked(job, job_needs_finalize_locked) == 0) {
         job_do_finalize_locked(job);
     }
 }
 
 /* Called with job_mutex held. */
 static void job_completed_locked(Job *job)
 {
     assert(job && job->txn && !job_is_completed_locked(job));
 
     job_update_rc_locked(job);
     trace_job_completed(job, job->ret);
     if (job->ret) {
         job_completed_txn_abort_locked(job);
     } else {
         job_completed_txn_success_locked(job);
     }
 }
 
 /**
  * Useful only as a type shim for aio_bh_schedule_oneshot.
  * Called with job_mutex *not* held.
  */
 static void job_exit(void *opaque)
 {
     Job *job = (Job *)opaque;
     JOB_LOCK_GUARD();
     job_ref_locked(job);
 
     /* This is a lie, we're not quiescent, but still doing the completion
      * callbacks. However, completion callbacks tend to involve operations that
      * drain block nodes, and if .drained_poll still returned true, we would
      * deadlock. */
     job->busy = false;
     job_event_idle_locked(job);
 
     job_completed_locked(job);
     job_unref_locked(job);
 }
 
 /**
  * All jobs must allow a pause point before entering their job proper. This
  * ensures that jobs can be paused prior to being started, then resumed later.
  */
 static void coroutine_fn job_co_entry(void *opaque)
 {
     Job *job = opaque;
     int ret;
 
     assert(job && job->driver && job->driver->run);
     WITH_JOB_LOCK_GUARD() {
         assert(job->aio_context == qemu_get_current_aio_context());
         job_pause_point_locked(job);
     }
     ret = job->driver->run(job, &job->err);
     WITH_JOB_LOCK_GUARD() {
         job->ret = ret;
         job->deferred_to_main_loop = true;
         job->busy = true;
     }
     aio_bh_schedule_oneshot(qemu_get_aio_context(), job_exit, job);
 }
 
 void job_start(Job *job)
 {
     assert(qemu_in_main_thread());
 
     WITH_JOB_LOCK_GUARD() {
         assert(job && !job_started_locked(job) && job->paused &&
             job->driver && job->driver->run);
         job->co = qemu_coroutine_create(job_co_entry, job);
         job->pause_count--;
         job->busy = true;
         job->paused = false;
         job_state_transition_locked(job, JOB_STATUS_RUNNING);
     }
     aio_co_enter(job->aio_context, job->co);
 }
 
 void job_cancel_locked(Job *job, bool force)
 {
     if (job->status == JOB_STATUS_CONCLUDED) {
         job_do_dismiss_locked(job);
         return;
     }
     job_cancel_async_locked(job, force);
     if (!job_started_locked(job)) {
         job_completed_locked(job);
     } else if (job->deferred_to_main_loop) {
         /*
          * job_cancel_async() ignores soft-cancel requests for jobs
          * that are already done (i.e. deferred to the main loop).  We
          * have to check again whether the job is really cancelled.
          * (job_cancel_requested() and job_is_cancelled() are equivalent
          * here, because job_cancel_async() will make soft-cancel
          * requests no-ops when deferred_to_main_loop is true.  We
          * choose to call job_is_cancelled() to show that we invoke
          * job_completed_txn_abort() only for force-cancelled jobs.)
          */
         if (job_is_cancelled_locked(job)) {
             job_completed_txn_abort_locked(job);
         }
     } else {
         job_enter_cond_locked(job, NULL);
     }
 }
 
 void job_user_cancel_locked(Job *job, bool force, Error **errp)
 {
     if (job_apply_verb_locked(job, JOB_VERB_CANCEL, errp)) {
         return;
     }
     job_cancel_locked(job, force);
 }
 
 /* A wrapper around job_cancel_locked() taking an Error ** parameter so it may
  * be used with job_finish_sync_locked() without the need for (rather nasty)
  * function pointer casts there.
  *
  * Called with job_mutex held.
  */
 static void job_cancel_err_locked(Job *job, Error **errp)
 {
     job_cancel_locked(job, false);
 }
 
 /**
  * Same as job_cancel_err(), but force-cancel.
  * Called with job_mutex held.
  */
 static void job_force_cancel_err_locked(Job *job, Error **errp)
 {
     job_cancel_locked(job, true);
 }
 
 int job_cancel_sync_locked(Job *job, bool force)
 {
     if (force) {
         return job_finish_sync_locked(job, &job_force_cancel_err_locked, NULL);
     } else {
         return job_finish_sync_locked(job, &job_cancel_err_locked, NULL);
     }
 }
 
 int job_cancel_sync(Job *job, bool force)
 {
     JOB_LOCK_GUARD();
     return job_cancel_sync_locked(job, force);
 }
 
 void job_cancel_sync_all(void)
 {
     Job *job;
     JOB_LOCK_GUARD();
 
     while ((job = job_next_locked(NULL))) {
         job_cancel_sync_locked(job, true);
     }
 }
 
 int job_complete_sync_locked(Job *job, Error **errp)
 {
     return job_finish_sync_locked(job, job_complete_locked, errp);
 }
 
 void job_complete_locked(Job *job, Error **errp)
 {
     /* Should not be reachable via external interface for internal jobs */
     assert(job->id);
     GLOBAL_STATE_CODE();
     if (job_apply_verb_locked(job, JOB_VERB_COMPLETE, errp)) {
         return;
     }
     if (job_cancel_requested_locked(job) || !job->driver->complete) {
         error_setg(errp, "The active block job '%s' cannot be completed",
                    job->id);
         return;
     }
 
     job_unlock();
     job->driver->complete(job, errp);
     job_lock();
 }
 
 int job_finish_sync_locked(Job *job,
                            void (*finish)(Job *, Error **errp),
                            Error **errp)
 {
     Error *local_err = NULL;
     int ret;
     GLOBAL_STATE_CODE();
 
     job_ref_locked(job);
 
     if (finish) {
         finish(job, &local_err);
     }
     if (local_err) {
         error_propagate(errp, local_err);
         job_unref_locked(job);
         return -EBUSY;
     }
 
     job_unlock();
     AIO_WAIT_WHILE_UNLOCKED(job->aio_context,
                             (job_enter(job), !job_is_completed(job)));
     job_lock();
 
     ret = (job_is_cancelled_locked(job) && job->ret == 0)
           ? -ECANCELED : job->ret;
     job_unref_locked(job);
     return ret;
 }