job: Add job_drain()

block_job_drain() contains a blk_drain() call which cannot be moved to
Job, so add a new JobDriver callback JobDriver.drain which has a common
implementation for all BlockJobs. In addition to this we keep the
existing BlockJobDriver.drain callback that is called by the common
drain implementation for all block jobs.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>

2 files changed, 25 insertions, 0 deletions

diff --git a/include/block/blockjob_int.h b/include/block/blockjob_int.h
index bf2b762808..38fe22d7e0 100644
--- a/include/block/blockjob_int.h
+++ b/include/block/blockjob_int.h
@@ -65,6 +65,10 @@ struct BlockJobDriver {
      * If the callback is not NULL, it will be invoked when the job has to be
      * synchronously cancelled or completed; it should drain BlockDriverStates
      * as required to ensure progress.
+     *
+     * Block jobs must use the default implementation for job_driver.drain,
+     * which will in turn call this callback after doing generic block job
+     * stuff.
      */
     void (*drain)(BlockJob *job);
 };
@@ -112,6 +116,14 @@ void block_job_free(Job *job);
 void block_job_user_resume(Job *job);
 
 /**
+ * block_job_drain:
+ * Callback to be used for JobDriver.drain in all block jobs. Drains the main
+ * block node associated with the block jobs and calls BlockJobDriver.drain for
+ * job-specific actions.
+ */
+void block_job_drain(Job *job);
+
+/**
  * block_job_yield:
  * @job: The job that calls the function.
  *
diff --git a/include/qemu/job.h b/include/qemu/job.h
index 2648c74281..aebc1959e6 100644
--- a/include/qemu/job.h
+++ b/include/qemu/job.h
@@ -167,6 +167,13 @@ struct JobDriver {
      */
     void (*user_resume)(Job *job);
 
+    /*
+     * If the callback is not NULL, it will be invoked when the job has to be
+     * synchronously cancelled or completed; it should drain any activities
+     * as required to ensure progress.
+     */
+    void (*drain)(Job *job);
+
     /**
      * If the callback is not NULL, it will be invoked when all the jobs
      * belonging to the same transaction complete; or upon this job's
@@ -325,6 +332,12 @@ bool job_user_paused(Job *job);
  */
 void job_user_resume(Job *job, Error **errp);
 
+/*
+ * Drain any activities as required to ensure progress. This can be called in a
+ * loop to synchronously complete a job.
+ */
+void job_drain(Job *job);
+
 /**
  * Get the next element from the list of block jobs after @job, or the
  * first one if @job is %NULL.