Currently there is no way to tell if write operation invoked via

vn_start_write() on the given vnode will be successful. VOP_LEASE() may
help to solve this problem, but its return value ignored nearly everywhere.
For now just assume that the missing upper layer on write means insufficient
access rights (which is correct for most cases).

1 files changed, 1 insertions, 1 deletions

diff --git a/sys/miscfs/union/union_vnops.c b/sys/miscfs/union/union_vnops.c
index 93922ecabaaa..3402825820f6 100644
--- a/sys/miscfs/union/union_vnops.c
+++ b/sys/miscfs/union/union_vnops.c
@@ -1630,7 +1630,7 @@ union_getwritemount(ap)
 			return (EOPNOTSUPP);
 		}
 		VI_UNLOCK(vp);
-		panic("union_getwritemount: missing upper layer");
+		return (EACCES);
 	}
 	return(VOP_GETWRITEMOUNT(uvp, ap->a_mpp));
 }