jobs: change start callback to run callback

Presently we codify the entry point for a job as the "start" callback,
but a more apt name would be "run" to clarify the idea that when this
function returns we consider the job to have "finished," except for
any cleanup which occurs in separate callbacks later.

As part of this clarification, change the signature to include an error
object and a return code. The error ptr is not yet used, and the return
code while captured, will be overwritten by actions in the job_completed
function.
Signed-off-by: NJohn Snow <jsnow@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Message-id: 20180830015734.19765-2-jsnow@redhat.com
Reviewed-by: NJeff Cody <jcody@redhat.com>
Signed-off-by: NMax Reitz <mreitz@redhat.com>

block/backup.c

@@ -480,9 +480,9 @@ static void backup_incremental_init_copy_bitmap(BackupBlockJob *job)
     bdrv_dirty_iter_free(dbi);
 }
 
-static void coroutine_fn backup_run(void *opaque)
+static int coroutine_fn backup_run(Job *opaque_job, Error **errp)
 {
-    BackupBlockJob *job = opaque;
+    BackupBlockJob *job = container_of(opaque_job, BackupBlockJob, common.job);
     BackupCompleteData *data;
     BlockDriverState *bs = blk_bs(job->common.blk);
     int64_t offset, nb_clusters;
@@ -587,6 +587,7 @@ static void coroutine_fn backup_run(void *opaque)
     data = g_malloc(sizeof(*data));
     data->ret = ret;
     job_defer_to_main_loop(&job->common.job, backup_complete, data);
+    return ret;
 }
 
 static const BlockJobDriver backup_job_driver = {
@@ -596,7 +597,7 @@ static const BlockJobDriver backup_job_driver = {
         .free                   = block_job_free,
         .user_resume            = block_job_user_resume,
         .drain                  = block_job_drain,
-        .start                  = backup_run,
+        .run                    = backup_run,
         .commit                 = backup_commit,
         .abort                  = backup_abort,
         .clean                  = backup_clean,

block/commit.c

@@ -134,9 +134,9 @@ static void commit_complete(Job *job, void *opaque)
     bdrv_unref(top);
 }
 
-static void coroutine_fn commit_run(void *opaque)
+static int coroutine_fn commit_run(Job *job, Error **errp)
 {
-    CommitBlockJob *s = opaque;
+    CommitBlockJob *s = container_of(job, CommitBlockJob, common.job);
     CommitCompleteData *data;
     int64_t offset;
     uint64_t delay_ns = 0;
@@ -213,6 +213,7 @@ out:
     data = g_malloc(sizeof(*data));
     data->ret = ret;
     job_defer_to_main_loop(&s->common.job, commit_complete, data);
+    return ret;
 }
 
 static const BlockJobDriver commit_job_driver = {
@@ -222,7 +223,7 @@ static const BlockJobDriver commit_job_driver = {
         .free          = block_job_free,
         .user_resume   = block_job_user_resume,
         .drain         = block_job_drain,
-        .start         = commit_run,
+        .run           = commit_run,
     },
 };
 

block/create.c

@@ -45,9 +45,9 @@ static void blockdev_create_complete(Job *job, void *opaque)
     job_completed(job, s->ret, s->err);
 }
 
-static void coroutine_fn blockdev_create_run(void *opaque)
+static int coroutine_fn blockdev_create_run(Job *job, Error **errp)
 {
-    BlockdevCreateJob *s = opaque;
+    BlockdevCreateJob *s = container_of(job, BlockdevCreateJob, common);
 
     job_progress_set_remaining(&s->common, 1);
     s->ret = s->drv->bdrv_co_create(s->opts, &s->err);
@@ -55,12 +55,14 @@ static void coroutine_fn blockdev_create_run(void *opaque)
 
     qapi_free_BlockdevCreateOptions(s->opts);
     job_defer_to_main_loop(&s->common, blockdev_create_complete, NULL);
+
+    return s->ret;
 }
 
 static const JobDriver blockdev_create_job_driver = {
     .instance_size = sizeof(BlockdevCreateJob),
     .job_type      = JOB_TYPE_CREATE,
-    .start         = blockdev_create_run,
+    .run           = blockdev_create_run,
 };
 
 void qmp_blockdev_create(const char *job_id, BlockdevCreateOptions *options,

block/mirror.c

@@ -812,9 +812,9 @@ static int mirror_flush(MirrorBlockJob *s)
     return ret;
 }
 
-static void coroutine_fn mirror_run(void *opaque)
+static int coroutine_fn mirror_run(Job *job, Error **errp)
 {
-    MirrorBlockJob *s = opaque;
+    MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job);
     MirrorExitData *data;
     BlockDriverState *bs = s->mirror_top_bs->backing->bs;
     BlockDriverState *target_bs = blk_bs(s->target);
@@ -1041,7 +1041,9 @@ immediate_exit:
     if (need_drain) {
         bdrv_drained_begin(bs);
     }
+
     job_defer_to_main_loop(&s->common.job, mirror_exit, data);
+    return ret;
 }
 
 static void mirror_complete(Job *job, Error **errp)
@@ -1138,7 +1140,7 @@ static const BlockJobDriver mirror_job_driver = {
         .free                   = block_job_free,
         .user_resume            = block_job_user_resume,
         .drain                  = block_job_drain,
-        .start                  = mirror_run,
+        .run                    = mirror_run,
         .pause                  = mirror_pause,
         .complete               = mirror_complete,
     },
@@ -1154,7 +1156,7 @@ static const BlockJobDriver commit_active_job_driver = {
         .free                   = block_job_free,
         .user_resume            = block_job_user_resume,
         .drain                  = block_job_drain,
-        .start                  = mirror_run,
+        .run                    = mirror_run,
         .pause                  = mirror_pause,
         .complete               = mirror_complete,
     },

block/stream.c

@@ -97,9 +97,9 @@ out:
     g_free(data);
 }
 
-static void coroutine_fn stream_run(void *opaque)
+static int coroutine_fn stream_run(Job *job, Error **errp)
 {
-    StreamBlockJob *s = opaque;
+    StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
     StreamCompleteData *data;
     BlockBackend *blk = s->common.blk;
     BlockDriverState *bs = blk_bs(blk);
@@ -206,6 +206,7 @@ out:
     data = g_malloc(sizeof(*data));
     data->ret = ret;
     job_defer_to_main_loop(&s->common.job, stream_complete, data);
+    return ret;
 }
 
 static const BlockJobDriver stream_job_driver = {
@@ -213,7 +214,7 @@ static const BlockJobDriver stream_job_driver = {
         .instance_size = sizeof(StreamBlockJob),
         .job_type      = JOB_TYPE_STREAM,
         .free          = block_job_free,
-        .start         = stream_run,
+        .run           = stream_run,
         .user_resume   = block_job_user_resume,
         .drain         = block_job_drain,
     },

include/qemu/job.h

@@ -169,7 +169,7 @@ struct JobDriver {
     JobType job_type;
 
     /** Mandatory: Entrypoint for the Coroutine. */
-    CoroutineEntry *start;
+    int coroutine_fn (*run)(Job *job, Error **errp);
 
     /**
      * If the callback is not NULL, it will be invoked when the job transitions

job.c

@@ -544,16 +544,16 @@ static void coroutine_fn job_co_entry(void *opaque)
 {
     Job *job = opaque;
 
-    assert(job && job->driver && job->driver->start);
+    assert(job && job->driver && job->driver->run);
     job_pause_point(job);
-    job->driver->start(job);
+    job->ret = job->driver->run(job, NULL);
 }
 
 
 void job_start(Job *job)
 {
     assert(job && !job_started(job) && job->paused &&
-           job->driver && job->driver->start);
+           job->driver && job->driver->run);
     job->co = qemu_coroutine_create(job_co_entry, job);
     job->pause_count--;
     job->busy = true;

tests/test-bdrv-drain.c

@@ -757,9 +757,9 @@ static void test_job_completed(Job *job, void *opaque)
     job_completed(job, 0, NULL);
 }
 
-static void coroutine_fn test_job_start(void *opaque)
+static int coroutine_fn test_job_run(Job *job, Error **errp)
 {
-    TestBlockJob *s = opaque;
+    TestBlockJob *s = container_of(job, TestBlockJob, common.job);
 
     job_transition_to_ready(&s->common.job);
     while (!s->should_complete) {
@@ -771,6 +771,7 @@ static void coroutine_fn test_job_start(void *opaque)
     }
 
     job_defer_to_main_loop(&s->common.job, test_job_completed, NULL);
+    return 0;
 }
 
 static void test_job_complete(Job *job, Error **errp)
@@ -785,7 +786,7 @@ BlockJobDriver test_job_driver = {
         .free           = block_job_free,
         .user_resume    = block_job_user_resume,
         .drain          = block_job_drain,
-        .start          = test_job_start,
+        .run            = test_job_run,
         .complete       = test_job_complete,
     },
 };

tests/test-blockjob-txn.c

@@ -38,25 +38,25 @@ static void test_block_job_complete(Job *job, void *opaque)
     bdrv_unref(bs);
 }
 
-static void coroutine_fn test_block_job_run(void *opaque)
+static int coroutine_fn test_block_job_run(Job *job, Error **errp)
 {
-    TestBlockJob *s = opaque;
-    BlockJob *job = &s->common;
+    TestBlockJob *s = container_of(job, TestBlockJob, common.job);
 
     while (s->iterations--) {
         if (s->use_timer) {
-            job_sleep_ns(&job->job, 0);
+            job_sleep_ns(job, 0);
         } else {
-            job_yield(&job->job);
+            job_yield(job);
         }
 
-        if (job_is_cancelled(&job->job)) {
+        if (job_is_cancelled(job)) {
             break;
         }
     }
 
-    job_defer_to_main_loop(&job->job, test_block_job_complete,
+    job_defer_to_main_loop(job, test_block_job_complete,
                            (void *)(intptr_t)s->rc);
+    return s->rc;
 }
 
 typedef struct {
@@ -80,7 +80,7 @@ static const BlockJobDriver test_block_job_driver = {
         .free          = block_job_free,
         .user_resume   = block_job_user_resume,
         .drain         = block_job_drain,
-        .start         = test_block_job_run,
+        .run           = test_block_job_run,
     },
 };
 

tests/test-blockjob.c

@@ -176,9 +176,9 @@ static void cancel_job_complete(Job *job, Error **errp)
     s->should_complete = true;
 }
 
-static void coroutine_fn cancel_job_start(void *opaque)
+static int coroutine_fn cancel_job_run(Job *job, Error **errp)
 {
-    CancelJob *s = opaque;
+    CancelJob *s = container_of(job, CancelJob, common.job);
 
     while (!s->should_complete) {
         if (job_is_cancelled(&s->common.job)) {
@@ -194,6 +194,7 @@ static void coroutine_fn cancel_job_start(void *opaque)
 
  defer:
     job_defer_to_main_loop(&s->common.job, cancel_job_completed, s);
+    return 0;
 }
 
 static const BlockJobDriver test_cancel_driver = {
@@ -202,7 +203,7 @@ static const BlockJobDriver test_cancel_driver = {
         .free          = block_job_free,
         .user_resume   = block_job_user_resume,
         .drain         = block_job_drain,
-        .start         = cancel_job_start,
+        .run           = cancel_job_run,
         .complete      = cancel_job_complete,
     },
 };