Functions that can do I/O are prime candidates for being coroutine_fns.  Make the
change for the one that is itself called only from coroutine_fns.  Unfortunately
vmdk does not use a coroutine_fn for the bulk of the open (like qcow2 does) so
vmdk_read_cid cannot have the same treatment.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block/vmdk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index f5f49018fe4a..3f8c731e32e8 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -376,7 +376,7 @@ out:
     return ret;
 }
 
-static int vmdk_is_cid_valid(BlockDriverState *bs)
+static int coroutine_fn vmdk_is_cid_valid(BlockDriverState *bs)
 {
     BDRVVmdkState *s = bs->opaque;
     uint32_t cur_pcid;
-- 
2.39.2