bpf: flowlabel in bpf_fib_lookup should be flowinfo

As Michal noted the flow struct takes both the flow label and priority.
Update the bpf_fib_lookup API to note that it is flowinfo and not just
the flow label.

Cc: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: NDavid Ahern <dsahern@gmail.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>

include/uapi/linux/bpf.h

@@ -2629,7 +2629,7 @@ struct bpf_fib_lookup {
 	union {
 		/* inputs to lookup */
 		__u8	tos;		/* AF_INET  */
-		__be32	flowlabel;	/* AF_INET6 */
+		__be32	flowinfo;	/* AF_INET6, flow_label + priority */
 
 		/* output: metric of fib result (IPv4/IPv6 only) */
 		__u32	rt_metric;

net/core/filter.c

@@ -4221,7 +4221,7 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
 		fl6.flowi6_oif = 0;
 		strict = RT6_LOOKUP_F_HAS_SADDR;
 	}
-	fl6.flowlabel = params->flowlabel;
+	fl6.flowlabel = params->flowinfo;
 	fl6.flowi6_scope = 0;
 	fl6.flowi6_flags = 0;
 	fl6.mp_hash = 0;

samples/bpf/xdp_fwd_kern.c

@@ -88,7 +88,7 @@ static __always_inline int xdp_fwd_flags(struct xdp_md *ctx, u32 flags)
 			return XDP_PASS;
 
 		fib_params.family	= AF_INET6;
-		fib_params.flowlabel	= *(__be32 *)ip6h & IPV6_FLOWINFO_MASK;
+		fib_params.flowinfo	= *(__be32 *)ip6h & IPV6_FLOWINFO_MASK;
 		fib_params.l4_protocol	= ip6h->nexthdr;
 		fib_params.sport	= 0;
 		fib_params.dport	= 0;