jobs: utilize job_exit shim

Utilize the job_exit shim by not calling job_defer_to_main_loop, and
where applicable, converting the deferred callback into the job_exit
callback.

This converts backup, stream, create, and the unit tests all at once.
Most of these jobs do not see any changes to the order in which they
clean up their resources, except the test-blockjob-txn test, which
now puts down its bs before job_completed is called.

This is safe for the same reason the reordering in the mirror job is
safe, because job_completed no longer runs under two locks, making
the unref safe even if it causes a flush.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180830015734.19765-7-jsnow@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

3 files changed, 10 insertions, 42 deletions

diff --git a/block/backup.c b/block/backup.c
index 1e965d54e5..a67b7fa96b 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -380,18 +380,6 @@ static BlockErrorAction backup_error_action(BackupBlockJob *job,
     }
 }
 
-typedef struct {
-    int ret;
-} BackupCompleteData;
-
-static void backup_complete(Job *job, void *opaque)
-{
-    BackupCompleteData *data = opaque;
-
-    job_completed(job, data->ret);
-    g_free(data);
-}
-
 static bool coroutine_fn yield_and_check(BackupBlockJob *job)
 {
     uint64_t delay_ns;
@@ -483,7 +471,6 @@ static void backup_incremental_init_copy_bitmap(BackupBlockJob *job)
 static int coroutine_fn backup_run(Job *opaque_job, Error **errp)
 {
     BackupBlockJob *job = container_of(opaque_job, BackupBlockJob, common.job);
-    BackupCompleteData *data;
     BlockDriverState *bs = blk_bs(job->common.blk);
     int64_t offset, nb_clusters;
     int ret = 0;
@@ -584,9 +571,6 @@ static int coroutine_fn backup_run(Job *opaque_job, Error **errp)
     qemu_co_rwlock_unlock(&job->flush_rwlock);
     hbitmap_free(job->copy_bitmap);
 
-    data = g_malloc(sizeof(*data));
-    data->ret = ret;
-    job_defer_to_main_loop(&job->common.job, backup_complete, data);
     return ret;
 }
 
diff --git a/block/create.c b/block/create.c
index 26a385c6c7..95341219ef 100644
--- a/block/create.c
+++ b/block/create.c
@@ -34,28 +34,20 @@ typedef struct BlockdevCreateJob {
     Job common;
     BlockDriver *drv;
     BlockdevCreateOptions *opts;
-    int ret;
 } BlockdevCreateJob;
 
-static void blockdev_create_complete(Job *job, void *opaque)
-{
-    BlockdevCreateJob *s = container_of(job, BlockdevCreateJob, common);
-
-    job_completed(job, s->ret);
-}
-
 static int coroutine_fn blockdev_create_run(Job *job, Error **errp)
 {
     BlockdevCreateJob *s = container_of(job, BlockdevCreateJob, common);
+    int ret;
 
     job_progress_set_remaining(&s->common, 1);
-    s->ret = s->drv->bdrv_co_create(s->opts, errp);
+    ret = s->drv->bdrv_co_create(s->opts, errp);
     job_progress_update(&s->common, 1);
 
     qapi_free_BlockdevCreateOptions(s->opts);
-    job_defer_to_main_loop(&s->common, blockdev_create_complete, NULL);
 
-    return s->ret;
+    return ret;
 }
 
 static const JobDriver blockdev_create_job_driver = {
diff --git a/block/stream.c b/block/stream.c
index 26a775386b..67e1e72e23 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -54,20 +54,16 @@ static int coroutine_fn stream_populate(BlockBackend *blk,
     return blk_co_preadv(blk, offset, qiov.size, &qiov, BDRV_REQ_COPY_ON_READ);
 }
 
-typedef struct {
-    int ret;
-} StreamCompleteData;
-
-static void stream_complete(Job *job, void *opaque)
+static void stream_exit(Job *job)
 {
     StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
     BlockJob *bjob = &s->common;
-    StreamCompleteData *data = opaque;
     BlockDriverState *bs = blk_bs(bjob->blk);
     BlockDriverState *base = s->base;
     Error *local_err = NULL;
+    int ret = job->ret;
 
-    if (!job_is_cancelled(job) && bs->backing && data->ret == 0) {
+    if (!job_is_cancelled(job) && bs->backing && ret == 0) {
         const char *base_id = NULL, *base_fmt = NULL;
         if (base) {
             base_id = s->backing_file_str;
@@ -75,11 +71,11 @@ static void stream_complete(Job *job, void *opaque)
                 base_fmt = base->drv->format_name;
             }
         }
-        data->ret = bdrv_change_backing_file(bs, base_id, base_fmt);
+        ret = bdrv_change_backing_file(bs, base_id, base_fmt);
         bdrv_set_backing_hd(bs, base, &local_err);
         if (local_err) {
             error_report_err(local_err);
-            data->ret = -EPERM;
+            ret = -EPERM;
             goto out;
         }
     }
@@ -93,14 +89,12 @@ out:
     }
 
     g_free(s->backing_file_str);
-    job_completed(job, data->ret);
-    g_free(data);
+    job->ret = ret;
 }
 
 static int coroutine_fn stream_run(Job *job, Error **errp)
 {
     StreamBlockJob *s = container_of(job, StreamBlockJob, common.job);
-    StreamCompleteData *data;
     BlockBackend *blk = s->common.blk;
     BlockDriverState *bs = blk_bs(blk);
     BlockDriverState *base = s->base;
@@ -203,9 +197,6 @@ static int coroutine_fn stream_run(Job *job, Error **errp)
 
 out:
     /* Modify backing chain and close BDSes in main loop */
-    data = g_malloc(sizeof(*data));
-    data->ret = ret;
-    job_defer_to_main_loop(&s->common.job, stream_complete, data);
     return ret;
 }
 
@@ -215,6 +206,7 @@ static const BlockJobDriver stream_job_driver = {
         .job_type      = JOB_TYPE_STREAM,
         .free          = block_job_free,
         .run           = stream_run,
+        .exit          = stream_exit,
         .user_resume   = block_job_user_resume,
         .drain         = block_job_drain,
     },