block/mirror: implement .cancel job handler

Cancel in-flight io on target to not waste the time.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210205163720.887197-6-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>

block/mirror.c

@@ -1179,6 +1179,14 @@ static bool mirror_drained_poll(BlockJob *job)
     return !!s->in_flight;
 }
 
+static void mirror_cancel(Job *job)
+{
+    MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job);
+    BlockDriverState *target = blk_bs(s->target);
+
+    bdrv_cancel_in_flight(target);
+}
+
 static const BlockJobDriver mirror_job_driver = {
     .job_driver = {
         .instance_size          = sizeof(MirrorBlockJob),
@@ -1190,6 +1198,7 @@ static const BlockJobDriver mirror_job_driver = {
         .abort                  = mirror_abort,
         .pause                  = mirror_pause,
         .complete               = mirror_complete,
+        .cancel                 = mirror_cancel,
     },
     .drained_poll           = mirror_drained_poll,
 };