If a coroutine is launched, but the coroutine pointer isn't stored
anywhere, debugging any problems inside the coroutine is quite hard.
Let's store the coroutine pointer of a mirror operation in MirrorOp to
have it available in the debugger.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 block/mirror.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block/mirror.c b/block/mirror.c
index f0f2d9dff1..8959e4255f 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -103,6 +103,7 @@ struct MirrorOp {
     bool is_pseudo_op;
     bool is_active_write;
     CoQueue waiting_requests;
+    Coroutine *co;
 
     QTAILQ_ENTRY(MirrorOp) next;
 };
@@ -429,6 +430,7 @@ static unsigned mirror_perform(MirrorBlockJob *s, int64_t offset,
     default:
         abort();
     }
+    op->co = co;
 
     QTAILQ_INSERT_TAIL(&s->ops_in_flight, op, next);
     qemu_coroutine_enter(co);
-- 
2.20.1