nfsd4: split stateowners into open and lockowners

The stateowner has some fields that only make sense for openowners, and
some that only make sense for lockowners, and I find it a lot clearer if
those are separated out.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
index 27a3dfa..f95a724 100644
--- a/fs/nfsd/xdr4.h
+++ b/fs/nfsd/xdr4.h
@@ -227,7 +227,7 @@
 	struct nfsd4_change_info  op_cinfo; /* response */
 	u32		op_rflags;          /* response */
 	int		op_truncate;        /* used during processing */
-	struct nfs4_stateowner *op_stateowner; /* used during processing */
+	struct nfs4_openowner *op_openowner; /* used during processing */
 	struct nfs4_acl *op_acl;
 };
 #define op_iattr	iattr