nfs: fix bug about IPv6 address scope checking

The result from ipv6_addr_scope() is a set of flags, not a single value,
so we can't just compare the result with  IPV6_ADDR_SCOPE_LINKLOCAL.

This patch fixs the problem, and checks for unequal addresses before
scope_id.

Signed-off-by: Mi Jinlong <mijinlong@cn.fujitsu.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfs/client.c

@@ -336,11 +336,12 @@ static int nfs_sockaddr_match_ipaddr6(const struct sockaddr *sa1,
 	const struct sockaddr_in6 *sin1 = (const struct sockaddr_in6 *)sa1;
 	const struct sockaddr_in6 *sin2 = (const struct sockaddr_in6 *)sa2;
 
-	if (ipv6_addr_scope(&sin1->sin6_addr) == IPV6_ADDR_SCOPE_LINKLOCAL &&
-	    sin1->sin6_scope_id != sin2->sin6_scope_id)
+	if (!ipv6_addr_equal(&sin1->sin6_addr, &sin2->sin6_addr))
 		return 0;
+	else if (ipv6_addr_type(&sin1->sin6_addr) & IPV6_ADDR_LINKLOCAL)
+		return sin1->sin6_scope_id == sin2->sin6_scope_id;
 
-	return ipv6_addr_equal(&sin1->sin6_addr, &sin2->sin6_addr);
+	return 1;
 }
 #else	/* !defined(CONFIG_IPV6) && !defined(CONFIG_IPV6_MODULE) */
 static int nfs_sockaddr_match_ipaddr6(const struct sockaddr *sa1,