From eba3b5a78799d21dea05118b294524958f0ab592 Mon Sep 17 00:00:00 2001 From: Alexander Frolkin Date: Wed, 19 Jun 2013 10:54:25 +0100 Subject: ipvs: SH fallback and L4 hashing By default the SH scheduler rejects connections that are hashed onto a realserver of weight 0. This patch adds a flag to make SH choose a different realserver in this case, instead of rejecting the connection. The patch also adds a flag to make SH include the source port (TCP, UDP, SCTP) in the hash as well as the source address. This basically allows for deterministic round-robin load balancing (i.e., where any director in a cluster of directors with identical config will send the same packet the same way). The flags are service flags (IP_VS_SVC_F_SCHED*) so that these options can be set per service. They are set using a new option to ipvsadm. Signed-off-by: Alexander Frolkin Acked-by: Julian Anastasov Signed-off-by: Simon Horman --- net/netfilter/ipvs/ip_vs_sh.c | 100 +++++++++++++++++++++++++++++++++++------- 1 file changed, 85 insertions(+), 15 deletions(-) (limited to 'net') diff --git a/net/netfilter/ipvs/ip_vs_sh.c b/net/netfilter/ipvs/ip_vs_sh.c index e0d5d1653566..f16c027df15b 100644 --- a/net/netfilter/ipvs/ip_vs_sh.c +++ b/net/netfilter/ipvs/ip_vs_sh.c @@ -48,6 +48,10 @@ #include +#include +#include +#include + /* * IPVS SH bucket @@ -71,10 +75,19 @@ struct ip_vs_sh_state { struct ip_vs_sh_bucket buckets[IP_VS_SH_TAB_SIZE]; }; +/* Helper function to determine if server is unavailable */ +static inline bool is_unavailable(struct ip_vs_dest *dest) +{ + return atomic_read(&dest->weight) <= 0 || + dest->flags & IP_VS_DEST_F_OVERLOAD; +} + /* * Returns hash value for IPVS SH entry */ -static inline unsigned int ip_vs_sh_hashkey(int af, const union nf_inet_addr *addr) +static inline unsigned int +ip_vs_sh_hashkey(int af, const union nf_inet_addr *addr, + __be16 port, unsigned int offset) { __be32 addr_fold = addr->ip; @@ -83,7 +96,8 @@ static inline unsigned int ip_vs_sh_hashkey(int af, const union nf_inet_addr *ad addr_fold = addr->ip6[0]^addr->ip6[1]^ addr->ip6[2]^addr->ip6[3]; #endif - return (ntohl(addr_fold)*2654435761UL) & IP_VS_SH_TAB_MASK; + return (offset + (ntohs(port) + ntohl(addr_fold))*2654435761UL) & + IP_VS_SH_TAB_MASK; } @@ -91,12 +105,42 @@ static inline unsigned int ip_vs_sh_hashkey(int af, const union nf_inet_addr *ad * Get ip_vs_dest associated with supplied parameters. */ static inline struct ip_vs_dest * -ip_vs_sh_get(int af, struct ip_vs_sh_state *s, const union nf_inet_addr *addr) +ip_vs_sh_get(struct ip_vs_service *svc, struct ip_vs_sh_state *s, + const union nf_inet_addr *addr, __be16 port) { - return rcu_dereference(s->buckets[ip_vs_sh_hashkey(af, addr)].dest); + unsigned int hash = ip_vs_sh_hashkey(svc->af, addr, port, 0); + struct ip_vs_dest *dest = rcu_dereference(s->buckets[hash].dest); + + return (!dest || is_unavailable(dest)) ? NULL : dest; } +/* As ip_vs_sh_get, but with fallback if selected server is unavailable */ +static inline struct ip_vs_dest * +ip_vs_sh_get_fallback(struct ip_vs_service *svc, struct ip_vs_sh_state *s, + const union nf_inet_addr *addr, __be16 port) +{ + unsigned int offset; + unsigned int hash; + struct ip_vs_dest *dest; + + for (offset = 0; offset < IP_VS_SH_TAB_SIZE; offset++) { + hash = ip_vs_sh_hashkey(svc->af, addr, port, offset); + dest = rcu_dereference(s->buckets[hash].dest); + if (!dest) + break; + if (is_unavailable(dest)) + IP_VS_DBG_BUF(6, "SH: selected unavailable server " + "%s:%d (offset %d)", + IP_VS_DBG_ADDR(svc->af, &dest->addr), + ntohs(dest->port), offset); + else + return dest; + } + + return NULL; +} + /* * Assign all the hash buckets of the specified table with the service. */ @@ -213,13 +257,33 @@ static int ip_vs_sh_dest_changed(struct ip_vs_service *svc, } -/* - * If the dest flags is set with IP_VS_DEST_F_OVERLOAD, - * consider that the server is overloaded here. - */ -static inline int is_overloaded(struct ip_vs_dest *dest) +/* Helper function to get port number */ +static inline __be16 +ip_vs_sh_get_port(const struct sk_buff *skb, struct ip_vs_iphdr *iph) { - return dest->flags & IP_VS_DEST_F_OVERLOAD; + __be16 port; + struct tcphdr _tcph, *th; + struct udphdr _udph, *uh; + sctp_sctphdr_t _sctph, *sh; + + switch (iph->protocol) { + case IPPROTO_TCP: + th = skb_header_pointer(skb, iph->len, sizeof(_tcph), &_tcph); + port = th->source; + break; + case IPPROTO_UDP: + uh = skb_header_pointer(skb, iph->len, sizeof(_udph), &_udph); + port = uh->source; + break; + case IPPROTO_SCTP: + sh = skb_header_pointer(skb, iph->len, sizeof(_sctph), &_sctph); + port = sh->source; + break; + default: + port = 0; + } + + return port; } @@ -232,15 +296,21 @@ ip_vs_sh_schedule(struct ip_vs_service *svc, const struct sk_buff *skb, { struct ip_vs_dest *dest; struct ip_vs_sh_state *s; + __be16 port = 0; IP_VS_DBG(6, "ip_vs_sh_schedule(): Scheduling...\n"); + if (svc->flags & IP_VS_SVC_F_SCHED_SH_PORT) + port = ip_vs_sh_get_port(skb, iph); + s = (struct ip_vs_sh_state *) svc->sched_data; - dest = ip_vs_sh_get(svc->af, s, &iph->saddr); - if (!dest - || !(dest->flags & IP_VS_DEST_F_AVAILABLE) - || atomic_read(&dest->weight) <= 0 - || is_overloaded(dest)) { + + if (svc->flags & IP_VS_SVC_F_SCHED_SH_FALLBACK) + dest = ip_vs_sh_get_fallback(svc, s, &iph->saddr, port); + else + dest = ip_vs_sh_get(svc, s, &iph->saddr, port); + + if (!dest) { ip_vs_scheduler_err(svc, "no destination available"); return NULL; } -- cgit v1.2.3