job: drop job_drain

In job_finish_sync job_enter should be enough for a job to make some
progress and draining is a wrong tool for it. So use job_enter directly
here and drop job_drain with all related staff not used more.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Tested-by: John Snow <jsnow@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/job.c b/job.c
index 28dd48f..04409b4 100644
--- a/job.c
+++ b/job.c
@@ -523,16 +523,6 @@
     job_pause_point(job);
 }
 
-void job_drain(Job *job)
-{
-    /* If job is !busy this kicks it into the next pause point. */
-    job_enter(job);
-
-    if (job->driver->drain) {
-        job->driver->drain(job);
-    }
-}
-
 /* Assumes the block_job_mutex is held */
 static bool job_timer_not_pending(Job *job)
 {
@@ -991,7 +981,7 @@
     }
 
     AIO_WAIT_WHILE(job->aio_context,
-                   (job_drain(job), !job_is_completed(job)));
+                   (job_enter(job), !job_is_completed(job)));
 
     ret = (job_is_cancelled(job) && job->ret == 0) ? -ECANCELED : job->ret;
     job_unref(job);