hw/9pfs: Add reference counting for fid

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
diff --git a/hw/9pfs/virtio-9p.h b/hw/9pfs/virtio-9p.h
index 1d8c1b1..e16e5f4 100644
--- a/hw/9pfs/virtio-9p.h
+++ b/hw/9pfs/virtio-9p.h
@@ -203,6 +203,8 @@
 	V9fsXattr xattr;
     } fs;
     uid_t uid;
+    int ref;
+    int clunked;
     V9fsFidState *next;
 };