diff --git a/block.c b/block.c
index d015887..aae71c2 100644
--- a/block.c
+++ b/block.c
@@ -1042,6 +1042,8 @@ static void coroutine_fn bdrv_rw_co_entry(void *opaque)
 {
     RwCo *rwco = opaque;
 
+    printf("bdrv_rw_co_entry is_write %d sector_num %" PRId64 " nb_sectors %d =",
+           rwco->is_write, rwco->sector_num, rwco->nb_sectors);
     if (!rwco->is_write) {
         rwco->ret = bdrv_co_do_readv(rwco->bs, rwco->sector_num,
                                      rwco->nb_sectors, rwco->qiov);
@@ -1049,6 +1051,8 @@ static void coroutine_fn bdrv_rw_co_entry(void *opaque)
         rwco->ret = bdrv_co_do_writev(rwco->bs, rwco->sector_num,
                                       rwco->nb_sectors, rwco->qiov);
     }
+    assert(rwco->ret != NOT_DONE);
+    printf("%d\n", rwco->ret);
 }
 
 /*
@@ -1081,6 +1085,7 @@ static int bdrv_rw_co(BlockDriverState *bs, int64_t sector_num, uint8_t *
         co = qemu_coroutine_create(bdrv_rw_co_entry);
         qemu_coroutine_enter(co, &rwco);
         while (rwco.ret == NOT_DONE) {
+            printf("waiting for rwco.ret != NOT_DONE\n");
             qemu_aio_wait();
         }
     }