[PATCH 04/11] job: add .cancel handler for the driver

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

To be used in mirror in the following commit to cancel in-flight io on
target to not waste the time.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 include/qemu/job.h | 5 +++++
 job.c              | 3 +++
 2 files changed, 8 insertions(+)

diff --git a/include/qemu/job.h b/include/qemu/job.h
index 32aabb1c60..efc6fa7544 100644
--- a/include/qemu/job.h
+++ b/include/qemu/job.h
@@ -251,6 +251,11 @@ struct JobDriver {
      */
     void (*clean)(Job *job);
 
+    /**
+     * If the callback is not NULL, it will be invoked in job_cancel_async
+     */
+    void (*cancel)(Job *job);
+
 
     /** Called when the job is freed */
     void (*free)(Job *job);
diff --git a/job.c b/job.c
index 8fecf38960..65012dbd03 100644
--- a/job.c
+++ b/job.c
@@ -712,6 +712,9 @@ static int job_finalize_single(Job *job)
 
 static void job_cancel_async(Job *job, bool force)
 {
+    if (job->driver->cancel) {
+        job->driver->cancel(job);
+    }
     if (job->user_paused) {
         /* Do not call job_enter here, the caller will handle it.  */
         if (job->driver->user_resume) {
-- 
2.21.3