block/mirror: set .co for active-write MirrorOp objects

This field is unused, but it very helpful for debugging.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210702211636.228981-2-vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block/mirror.c b/block/mirror.c
index 019f6de..ad6aac2 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -1343,6 +1343,7 @@
         .bytes              = bytes,
         .is_active_write    = true,
         .is_in_flight       = true,
+        .co                 = qemu_coroutine_self(),
     };
     qemu_co_queue_init(&op->waiting_requests);
     QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next);