NFS4: Fix open bug when pnfs module blacklisted

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index 29fd23c..64f90d8 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -365,7 +365,7 @@
 pnfs_use_threshold(struct nfs4_threshold **dst, struct nfs4_threshold *src,
 		   struct nfs_server *nfss)
 {
-	return (dst && src && src->bm != 0 &&
+	return (dst && src && src->bm != 0 && nfss->pnfs_curr_ld &&
 					nfss->pnfs_curr_ld->id == src->l_type);
 }