[net-next-2.6.git] / net / netfilter / ipvs / ip_vs_dh.c

/*
 * IPVS:        Destination Hashing scheduling module
 *
 * Authors:     Wensong Zhang <wensong@gnuchina.org>
 *
 *              Inspired by the consistent hashing scheduler patch from
 *              Thomas Proell <proellt@gmx.de>
 *
 *              This program is free software; you can redistribute it and/or
 *              modify it under the terms of the GNU General Public License
 *              as published by the Free Software Foundation; either version
 *              2 of the License, or (at your option) any later version.
 *
 * Changes:
 *
 */

/*
 * The dh algorithm is to select server by the hash key of destination IP
 * address. The pseudo code is as follows:
 *
 *       n <- servernode[dest_ip];
 *       if (n is dead) OR
 *          (n is overloaded) OR (n.weight <= 0) then
 *                 return NULL;
 *
 *       return n;
 *
 * Notes that servernode is a 256-bucket hash table that maps the hash
 * index derived from packet destination IP address to the current server
 * array. If the dh scheduler is used in cache cluster, it is good to
 * combine it with cache_bypass feature. When the statically assigned
 * server is dead or overloaded, the load balancer can bypass the cache
 * server and send requests to the original server directly.
 *
 */

#define KMSG_COMPONENT "IPVS"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/ip.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>

#include <net/ip_vs.h>


/*
 *      IPVS DH bucket
 */
struct ip_vs_dh_bucket {
	struct ip_vs_dest       *dest;          /* real server (cache) */
};

/*
 *     for IPVS DH entry hash table
 */
#ifndef CONFIG_IP_VS_DH_TAB_BITS
#define CONFIG_IP_VS_DH_TAB_BITS        8
#endif
#define IP_VS_DH_TAB_BITS               CONFIG_IP_VS_DH_TAB_BITS
#define IP_VS_DH_TAB_SIZE               (1 << IP_VS_DH_TAB_BITS)
#define IP_VS_DH_TAB_MASK               (IP_VS_DH_TAB_SIZE - 1)


/*
 *	Returns hash value for IPVS DH entry
 */
static inline unsigned ip_vs_dh_hashkey(int af, const union nf_inet_addr *addr)
{
	__be32 addr_fold = addr->ip;

#ifdef CONFIG_IP_VS_IPV6
	if (af == AF_INET6)
		addr_fold = addr->ip6[0]^addr->ip6[1]^
			    addr->ip6[2]^addr->ip6[3];
#endif
	return (ntohl(addr_fold)*2654435761UL) & IP_VS_DH_TAB_MASK;
}


/*
 *      Get ip_vs_dest associated with supplied parameters.
 */
static inline struct ip_vs_dest *
ip_vs_dh_get(int af, struct ip_vs_dh_bucket *tbl,
	     const union nf_inet_addr *addr)
{
	return (tbl[ip_vs_dh_hashkey(af, addr)]).dest;
}


/*
 *      Assign all the hash buckets of the specified table with the service.
 */
static int
ip_vs_dh_assign(struct ip_vs_dh_bucket *tbl, struct ip_vs_service *svc)
{
	int i;
	struct ip_vs_dh_bucket *b;
	struct list_head *p;
	struct ip_vs_dest *dest;

	b = tbl;
	p = &svc->destinations;
	for (i=0; i<IP_VS_DH_TAB_SIZE; i++) {
		if (list_empty(p)) {
			b->dest = NULL;
		} else {
			if (p == &svc->destinations)
				p = p->next;

			dest = list_entry(p, struct ip_vs_dest, n_list);
			atomic_inc(&dest->refcnt);
			b->dest = dest;

			p = p->next;
		}
		b++;
	}
	return 0;
}


/*
 *      Flush all the hash buckets of the specified table.
 */
static void ip_vs_dh_flush(struct ip_vs_dh_bucket *tbl)
{
	int i;
	struct ip_vs_dh_bucket *b;

	b = tbl;
	for (i=0; i<IP_VS_DH_TAB_SIZE; i++) {
		if (b->dest) {
			atomic_dec(&b->dest->refcnt);
			b->dest = NULL;
		}
		b++;
	}
}


static int ip_vs_dh_init_svc(struct ip_vs_service *svc)
{
	struct ip_vs_dh_bucket *tbl;

	/* allocate the DH table for this service */
	tbl = kmalloc(sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE,
		      GFP_ATOMIC);
	if (tbl == NULL) {
		pr_err("%s(): no memory\n", __func__);
		return -ENOMEM;
	}
	svc->sched_data = tbl;
	IP_VS_DBG(6, "DH hash table (memory=%Zdbytes) allocated for "
		  "current service\n",
		  sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE);

	/* assign the hash buckets with the updated service */
	ip_vs_dh_assign(tbl, svc);

	return 0;
}


static int ip_vs_dh_done_svc(struct ip_vs_service *svc)
{
	struct ip_vs_dh_bucket *tbl = svc->sched_data;

	/* got to clean up hash buckets here */
	ip_vs_dh_flush(tbl);

	/* release the table itself */
	kfree(svc->sched_data);
	IP_VS_DBG(6, "DH hash table (memory=%Zdbytes) released\n",
		  sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE);

	return 0;
}


static int ip_vs_dh_update_svc(struct ip_vs_service *svc)
{
	struct ip_vs_dh_bucket *tbl = svc->sched_data;

	/* got to clean up hash buckets here */
	ip_vs_dh_flush(tbl);

	/* assign the hash buckets with the updated service */
	ip_vs_dh_assign(tbl, svc);

	return 0;
}


/*
 *      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)
{
	return dest->flags & IP_VS_DEST_F_OVERLOAD;
}


/*
 *      Destination hashing scheduling
 */
static struct ip_vs_dest *
ip_vs_dh_schedule(struct ip_vs_service *svc, const struct sk_buff *skb)
{
	struct ip_vs_dest *dest;
	struct ip_vs_dh_bucket *tbl;
	struct ip_vs_iphdr iph;

	ip_vs_fill_iphdr(svc->af, skb_network_header(skb), &iph);

	IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);

	tbl = (struct ip_vs_dh_bucket *)svc->sched_data;
	dest = ip_vs_dh_get(svc->af, tbl, &iph.daddr);
	if (!dest
	    || !(dest->flags & IP_VS_DEST_F_AVAILABLE)
	    || atomic_read(&dest->weight) <= 0
	    || is_overloaded(dest)) {
		return NULL;
	}

	IP_VS_DBG_BUF(6, "DH: destination IP address %s --> server %s:%d\n",
		      IP_VS_DBG_ADDR(svc->af, &iph.daddr),
		      IP_VS_DBG_ADDR(svc->af, &dest->addr),
		      ntohs(dest->port));

	return dest;
}


/*
 *      IPVS DH Scheduler structure
 */
static struct ip_vs_scheduler ip_vs_dh_scheduler =
{
	.name =			"dh",
	.refcnt =		ATOMIC_INIT(0),
	.module =		THIS_MODULE,
	.n_list =		LIST_HEAD_INIT(ip_vs_dh_scheduler.n_list),
	.init_service =		ip_vs_dh_init_svc,
	.done_service =		ip_vs_dh_done_svc,
	.update_service =	ip_vs_dh_update_svc,
	.schedule =		ip_vs_dh_schedule,
};


static int __init ip_vs_dh_init(void)
{
	return register_ip_vs_scheduler(&ip_vs_dh_scheduler);
}


static void __exit ip_vs_dh_cleanup(void)
{
	unregister_ip_vs_scheduler(&ip_vs_dh_scheduler);
}


module_init(ip_vs_dh_init);
module_exit(ip_vs_dh_cleanup);
MODULE_LICENSE("GPL");
Commit	Line	Data
cb7f6a7b JV	1	/*
	2	* IPVS: Destination Hashing scheduling module
	3	*
	4	* Authors: Wensong Zhang <wensong@gnuchina.org>
	5	*
	6	* Inspired by the consistent hashing scheduler patch from
	7	* Thomas Proell <proellt@gmx.de>
	8	*
	9	* This program is free software; you can redistribute it and/or
	10	* modify it under the terms of the GNU General Public License
	11	* as published by the Free Software Foundation; either version
	12	* 2 of the License, or (at your option) any later version.
	13	*
	14	* Changes:
	15	*
	16	*/
	17
	18	/*
	19	* The dh algorithm is to select server by the hash key of destination IP
	20	* address. The pseudo code is as follows:
	21	*
	22	* n <- servernode[dest_ip];
	23	* if (n is dead) OR
	24	* (n is overloaded) OR (n.weight <= 0) then
	25	* return NULL;
	26	*
	27	* return n;
	28	*
	29	* Notes that servernode is a 256-bucket hash table that maps the hash
	30	* index derived from packet destination IP address to the current server
	31	* array. If the dh scheduler is used in cache cluster, it is good to
	32	* combine it with cache_bypass feature. When the statically assigned
	33	* server is dead or overloaded, the load balancer can bypass the cache
	34	* server and send requests to the original server directly.
	35	*
	36	*/
	37
9aada7ac HE	38	#define KMSG_COMPONENT "IPVS"
	39	#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
	40
cb7f6a7b	41	#include <linux/ip.h>
5a0e3ad6	42	#include <linux/slab.h>
cb7f6a7b JV	43	#include <linux/module.h>
	44	#include <linux/kernel.h>
	45	#include <linux/skbuff.h>
	46
	47	#include <net/ip_vs.h>
	48
	49
	50	/*
	51	* IPVS DH bucket
	52	*/
	53	struct ip_vs_dh_bucket {
	54	struct ip_vs_dest dest; / real server (cache) */
	55	};
	56
	57	/*
	58	* for IPVS DH entry hash table
	59	*/
	60	#ifndef CONFIG_IP_VS_DH_TAB_BITS
	61	#define CONFIG_IP_VS_DH_TAB_BITS 8
	62	#endif
	63	#define IP_VS_DH_TAB_BITS CONFIG_IP_VS_DH_TAB_BITS
	64	#define IP_VS_DH_TAB_SIZE (1 << IP_VS_DH_TAB_BITS)
	65	#define IP_VS_DH_TAB_MASK (IP_VS_DH_TAB_SIZE - 1)
	66
	67
	68	/*
	69	* Returns hash value for IPVS DH entry
	70	*/
20971a0a	71	static inline unsigned ip_vs_dh_hashkey(int af, const union nf_inet_addr *addr)
cb7f6a7b	72	{
20971a0a JV	73	__be32 addr_fold = addr->ip;
	74
	75	#ifdef CONFIG_IP_VS_IPV6
	76	if (af == AF_INET6)
	77	addr_fold = addr->ip6[0]^addr->ip6[1]^
	78	addr->ip6[2]^addr->ip6[3];
	79	#endif
	80	return (ntohl(addr_fold)*2654435761UL) & IP_VS_DH_TAB_MASK;
cb7f6a7b JV	81	}
	82
	83
	84	/*
	85	* Get ip_vs_dest associated with supplied parameters.
	86	*/
	87	static inline struct ip_vs_dest *
20971a0a JV	88	ip_vs_dh_get(int af, struct ip_vs_dh_bucket *tbl,
20971a0a JV	89	const union nf_inet_addr *addr)
cb7f6a7b	90	{
20971a0a	91	return (tbl[ip_vs_dh_hashkey(af, addr)]).dest;
cb7f6a7b JV	92	}
	93
	94
	95	/*
	96	* Assign all the hash buckets of the specified table with the service.
	97	*/
	98	static int
	99	ip_vs_dh_assign(struct ip_vs_dh_bucket tbl, struct ip_vs_service svc)
	100	{
	101	int i;
	102	struct ip_vs_dh_bucket *b;
	103	struct list_head *p;
	104	struct ip_vs_dest *dest;
	105
	106	b = tbl;
	107	p = &svc->destinations;
	108	for (i=0; i<IP_VS_DH_TAB_SIZE; i++) {
	109	if (list_empty(p)) {
	110	b->dest = NULL;
	111	} else {
	112	if (p == &svc->destinations)
	113	p = p->next;
	114
	115	dest = list_entry(p, struct ip_vs_dest, n_list);
	116	atomic_inc(&dest->refcnt);
	117	b->dest = dest;
	118
	119	p = p->next;
	120	}
	121	b++;
	122	}
	123	return 0;
	124	}
	125
	126
	127	/*
	128	* Flush all the hash buckets of the specified table.
	129	*/
	130	static void ip_vs_dh_flush(struct ip_vs_dh_bucket *tbl)
	131	{
	132	int i;
	133	struct ip_vs_dh_bucket *b;
	134
	135	b = tbl;
	136	for (i=0; i<IP_VS_DH_TAB_SIZE; i++) {
	137	if (b->dest) {
	138	atomic_dec(&b->dest->refcnt);
	139	b->dest = NULL;
	140	}
	141	b++;
	142	}
	143	}
	144
	145
	146	static int ip_vs_dh_init_svc(struct ip_vs_service *svc)
	147	{
	148	struct ip_vs_dh_bucket *tbl;
	149
	150	/* allocate the DH table for this service */
	151	tbl = kmalloc(sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE,
	152	GFP_ATOMIC);
	153	if (tbl == NULL) {
1e3e238e	154	pr_err("%s(): no memory\n", __func__);
cb7f6a7b JV	155	return -ENOMEM;
	156	}
	157	svc->sched_data = tbl;
	158	IP_VS_DBG(6, "DH hash table (memory=%Zdbytes) allocated for "
	159	"current service\n",
	160	sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE);
	161
	162	/* assign the hash buckets with the updated service */
	163	ip_vs_dh_assign(tbl, svc);
	164
	165	return 0;
	166	}
	167
	168
	169	static int ip_vs_dh_done_svc(struct ip_vs_service *svc)
	170	{
	171	struct ip_vs_dh_bucket *tbl = svc->sched_data;
	172
	173	/* got to clean up hash buckets here */
	174	ip_vs_dh_flush(tbl);
	175
	176	/* release the table itself */
	177	kfree(svc->sched_data);
	178	IP_VS_DBG(6, "DH hash table (memory=%Zdbytes) released\n",
	179	sizeof(struct ip_vs_dh_bucket)*IP_VS_DH_TAB_SIZE);
	180
	181	return 0;
	182	}
	183
	184
	185	static int ip_vs_dh_update_svc(struct ip_vs_service *svc)
	186	{
	187	struct ip_vs_dh_bucket *tbl = svc->sched_data;
	188
	189	/* got to clean up hash buckets here */
	190	ip_vs_dh_flush(tbl);
	191
	192	/* assign the hash buckets with the updated service */
	193	ip_vs_dh_assign(tbl, svc);
	194
	195	return 0;
	196	}
	197
	198
	199	/*
	200	* If the dest flags is set with IP_VS_DEST_F_OVERLOAD,
	201	* consider that the server is overloaded here.
	202	*/
	203	static inline int is_overloaded(struct ip_vs_dest *dest)
	204	{
	205	return dest->flags & IP_VS_DEST_F_OVERLOAD;
	206	}
	207
	208
	209	/*
	210	* Destination hashing scheduling
	211	*/
	212	static struct ip_vs_dest *
	213	ip_vs_dh_schedule(struct ip_vs_service svc, const struct sk_buff skb)
	214	{
	215	struct ip_vs_dest *dest;
	216	struct ip_vs_dh_bucket *tbl;
20971a0a JV	217	struct ip_vs_iphdr iph;
	218
	219	ip_vs_fill_iphdr(svc->af, skb_network_header(skb), &iph);
cb7f6a7b	220
1e3e238e	221	IP_VS_DBG(6, "%s(): Scheduling...\n", __func__);
cb7f6a7b JV	222
cb7f6a7b JV	223	tbl = (struct ip_vs_dh_bucket *)svc->sched_data;
20971a0a	224	dest = ip_vs_dh_get(svc->af, tbl, &iph.daddr);
cb7f6a7b JV	225	if (!dest
	226	\|\| !(dest->flags & IP_VS_DEST_F_AVAILABLE)
	227	\|\| atomic_read(&dest->weight) <= 0
	228	\|\| is_overloaded(dest)) {
	229	return NULL;
	230	}
	231
20971a0a JV	232	IP_VS_DBG_BUF(6, "DH: destination IP address %s --> server %s:%d\n",
	233	IP_VS_DBG_ADDR(svc->af, &iph.daddr),
	234	IP_VS_DBG_ADDR(svc->af, &dest->addr),
	235	ntohs(dest->port));
cb7f6a7b JV	236
	237	return dest;
	238	}
	239
	240
	241	/*
	242	* IPVS DH Scheduler structure
	243	*/
	244	static struct ip_vs_scheduler ip_vs_dh_scheduler =
	245	{
	246	.name = "dh",
	247	.refcnt = ATOMIC_INIT(0),
	248	.module = THIS_MODULE,
	249	.n_list = LIST_HEAD_INIT(ip_vs_dh_scheduler.n_list),
cb7f6a7b JV	250	.init_service = ip_vs_dh_init_svc,
	251	.done_service = ip_vs_dh_done_svc,
	252	.update_service = ip_vs_dh_update_svc,
	253	.schedule = ip_vs_dh_schedule,
	254	};
	255
	256
	257	static int __init ip_vs_dh_init(void)
	258	{
	259	return register_ip_vs_scheduler(&ip_vs_dh_scheduler);
	260	}
	261
	262
	263	static void __exit ip_vs_dh_cleanup(void)
	264	{
	265	unregister_ip_vs_scheduler(&ip_vs_dh_scheduler);
	266	}
	267
	268
	269	module_init(ip_vs_dh_init);
	270	module_exit(ip_vs_dh_cleanup);
	271	MODULE_LICENSE("GPL");