NFS: Don't use GFP_KERNEL in rpcsec_gss downcalls

Again, we can deadlock if the memory reclaim triggers a writeback that
requires a rpcsec_gss credential lookup.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/sunrpc/gss_krb5.h b/include/linux/sunrpc/gss_krb5.h
index 5e774a5..5af2931 100644
--- a/include/linux/sunrpc/gss_krb5.h
+++ b/include/linux/sunrpc/gss_krb5.h
@@ -295,7 +295,8 @@
 krb5_derive_key(const struct gss_krb5_enctype *gk5e,
 		const struct xdr_netobj *inkey,
 		struct xdr_netobj *outkey,
-		const struct xdr_netobj *in_constant);
+		const struct xdr_netobj *in_constant,
+		gfp_t gfp_mask);
 
 u32
 gss_krb5_des3_make_key(const struct gss_krb5_enctype *gk5e,