ipv4: Remember FIB alias list head and table in lookup results.

This will be used later to implement fib_select_default() in a
completely generic manner, instead of the current situation where the
default route is re-looked up in the TRIE/HASH table and then the
available aliases are analyzed.

Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip_fib.h

@@ -96,12 +96,15 @@ struct fib_info {
 struct fib_rule;
 #endif
 
+struct fib_table;
 struct fib_result {
 	unsigned char	prefixlen;
 	unsigned char	nh_sel;
 	unsigned char	type;
 	unsigned char	scope;
 	struct fib_info *fi;
+	struct fib_table *table;
+	struct list_head *fa_head;
 #ifdef CONFIG_IP_MULTIPLE_TABLES
 	struct fib_rule	*r;
 #endif

net/ipv4/fib_hash.c

@@ -288,7 +288,7 @@ int fib_table_lookup(struct fib_table *tb,
 				if (f->fn_key != k)
 					continue;
 
-				err = fib_semantic_match(&f->fn_alias,
+				err = fib_semantic_match(tb, &f->fn_alias,
 						 flp, res,
 						 fz->fz_order, fib_flags);
 				if (err <= 0)

net/ipv4/fib_lookup.h

@@ -25,7 +25,7 @@ static inline void fib_alias_accessed(struct fib_alias *fa)
 }
 
 /* Exported by fib_semantics.c */
-extern int fib_semantic_match(struct list_head *head,
+extern int fib_semantic_match(struct fib_table *tb, struct list_head *head,
 			      const struct flowi *flp,
 			      struct fib_result *res, int prefixlen, int fib_flags);
 extern void fib_release_info(struct fib_info *);

net/ipv4/fib_semantics.c

@@ -889,8 +889,9 @@ failure:
 }
 
 /* Note! fib_semantic_match intentionally uses  RCU list functions. */
-int fib_semantic_match(struct list_head *head, const struct flowi *flp,
-		       struct fib_result *res, int prefixlen, int fib_flags)
+int fib_semantic_match(struct fib_table *tb, struct list_head *head,
+		       const struct flowi *flp, struct fib_result *res,
+		       int prefixlen, int fib_flags)
 {
 	struct fib_alias *fa;
 	int nh_sel = 0;
@@ -954,6 +955,8 @@ out_fill_res:
 	res->type = fa->fa_type;
 	res->scope = fa->fa_scope;
 	res->fi = fa->fa_info;
+	res->table = tb;
+	res->fa_head = head;
 	if (!(fib_flags & FIB_LOOKUP_NOREF))
 		atomic_inc(&res->fi->fib_clntref);
 	return 0;

net/ipv4/fib_trie.c

@@ -1340,7 +1340,7 @@ err:
 }
 
 /* should be called with rcu_read_lock */
-static int check_leaf(struct trie *t, struct leaf *l,
+static int check_leaf(struct fib_table *tb, struct trie *t, struct leaf *l,
 		      t_key key,  const struct flowi *flp,
 		      struct fib_result *res, int fib_flags)
 {
@@ -1356,7 +1356,7 @@ static int check_leaf(struct trie *t, struct leaf *l,
 		if (l->key != (key & ntohl(mask)))
 			continue;
 
-		err = fib_semantic_match(&li->falh, flp, res, plen, fib_flags);
+		err = fib_semantic_match(tb, &li->falh, flp, res, plen, fib_flags);
 
 #ifdef CONFIG_IP_FIB_TRIE_STATS
 		if (err <= 0)
@@ -1398,7 +1398,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi *flp,
 
 	/* Just a leaf? */
 	if (IS_LEAF(n)) {
-		ret = check_leaf(t, (struct leaf *)n, key, flp, res, fib_flags);
+		ret = check_leaf(tb, t, (struct leaf *)n, key, flp, res, fib_flags);
 		goto found;
 	}
 
@@ -1423,7 +1423,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi *flp,
 		}
 
 		if (IS_LEAF(n)) {
-			ret = check_leaf(t, (struct leaf *)n, key, flp, res, fib_flags);
+			ret = check_leaf(tb, t, (struct leaf *)n, key, flp, res, fib_flags);
 			if (ret > 0)
 				goto backtrace;
 			goto found;