[PATCH nfs-utils v2 1/4] exportfs/mountd/exportd: track the svc_export policy highest attribute

[Jeff Layton <jlayton@kernel.org>]

Record max_attr, the highest attribute in the kernel svc_export netlink
policy, in struct nfsd_export_policy. Follow-on work needs it to avoid
sending attributes that an older kernel would reject the whole entry
over.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 support/export/export_policy.c | 7 ++++++-
 support/include/exportfs.h     | 2 ++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/support/export/export_policy.c b/support/export/export_policy.c
index 9c0a099fb0c2..a0170cb87f91 100644
--- a/support/export/export_policy.c
+++ b/support/export/export_policy.c
@@ -40,6 +40,7 @@ struct export_policy_dump {
 	int		done;
 	int		do_idx;		/* the op's own policy */
 	/* per policy: */
+	int		max_attr[NL_POLICY_SLOTS];
 	int		reqs_idx[NL_POLICY_SLOTS];	/* REQUESTS nests this */
 	uint64_t	flags_mask[NL_POLICY_SLOTS];	/* mask of FLAGS */
 };
@@ -106,6 +107,8 @@ static void nl_policy_attrs(struct export_policy_dump *d, struct nlattr *attr)
 		nla_for_each_nested(a, pol, arem) {
 			int type = nla_type(a);
 
+			if (d->max_attr[idx] < type)
+				d->max_attr[idx] = type;
 			nla_for_each_nested(p, a, rem)
 				nl_policy_type_attr(d, idx, type, p);
 		}
@@ -219,8 +222,10 @@ int nfsd_export_policy_query(struct nfsd_export_policy *pol)
 	 * every kernel with the netlink export interface.
 	 */
 	cached.secinfo_flags = NFSEXP_SECINFO_FLAGS;
+	cached.max_attr = d.max_attr[svc];
 	have_cached = true;
-	xlog(D_NETLINK, "svc_export policy: flags 0x%x", cached.flags);
+	xlog(D_NETLINK, "svc_export policy: max attribute %d, flags 0x%x",
+	     cached.max_attr, cached.flags);
 	*pol = cached;
 	ret = 0;
 out:
diff --git a/support/include/exportfs.h b/support/include/exportfs.h
index d762e4533560..a7c145543075 100644
--- a/support/include/exportfs.h
+++ b/support/include/exportfs.h
@@ -170,6 +170,8 @@ struct nfskey *			key_lookup(char *hname);
 struct nfsd_export_policy {
 	unsigned int	flags;		/* export flags it knows */
 	unsigned int	secinfo_flags;	/* flags that may vary per flavor */
+	int		max_attr;	/* highest svc_export netlink attribute,
+					 * 0 if it did not say */
 };
 
 struct nfsd_export_policy *get_export_features(void);

-- 
2.56.0