[linux-block.git] / fs / nfs / dns_resolve.c

/*
 * linux/fs/nfs/dns_resolve.c
 *
 * Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
 *
 * Resolves DNS hostnames into valid ip addresses
 */

#ifdef CONFIG_NFS_USE_KERNEL_DNS

#include <linux/sunrpc/clnt.h>
#include <linux/dns_resolver.h>
#include "dns_resolve.h"

ssize_t nfs_dns_resolve_name(struct net *net, char *name, size_t namelen,
		struct sockaddr *sa, size_t salen)
{
	ssize_t ret;
	char *ip_addr = NULL;
	int ip_len;

	ip_len = dns_query(NULL, name, namelen, NULL, &ip_addr, NULL);
	if (ip_len > 0)
		ret = rpc_pton(net, ip_addr, ip_len, sa, salen);
	else
		ret = -ESRCH;
	kfree(ip_addr);
	return ret;
}

#else

#include <linux/hash.h>
#include <linux/string.h>
#include <linux/kmod.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/socket.h>
#include <linux/seq_file.h>
#include <linux/inet.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/cache.h>
#include <linux/sunrpc/svcauth.h>
#include <linux/sunrpc/rpc_pipe_fs.h>

#include "dns_resolve.h"
#include "cache_lib.h"
#include "netns.h"

#define NFS_DNS_HASHBITS 4
#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)

struct nfs_dns_ent {
	struct cache_head h;

	char *hostname;
	size_t namelen;

	struct sockaddr_storage addr;
	size_t addrlen;
};


static void nfs_dns_ent_update(struct cache_head *cnew,
		struct cache_head *ckey)
{
	struct nfs_dns_ent *new;
	struct nfs_dns_ent *key;

	new = container_of(cnew, struct nfs_dns_ent, h);
	key = container_of(ckey, struct nfs_dns_ent, h);

	memcpy(&new->addr, &key->addr, key->addrlen);
	new->addrlen = key->addrlen;
}

static void nfs_dns_ent_init(struct cache_head *cnew,
		struct cache_head *ckey)
{
	struct nfs_dns_ent *new;
	struct nfs_dns_ent *key;

	new = container_of(cnew, struct nfs_dns_ent, h);
	key = container_of(ckey, struct nfs_dns_ent, h);

	kfree(new->hostname);
	new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
	if (new->hostname) {
		new->namelen = key->namelen;
		nfs_dns_ent_update(cnew, ckey);
	} else {
		new->namelen = 0;
		new->addrlen = 0;
	}
}

static void nfs_dns_ent_put(struct kref *ref)
{
	struct nfs_dns_ent *item;

	item = container_of(ref, struct nfs_dns_ent, h.ref);
	kfree(item->hostname);
	kfree(item);
}

static struct cache_head *nfs_dns_ent_alloc(void)
{
	struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL);

	if (item != NULL) {
		item->hostname = NULL;
		item->namelen = 0;
		item->addrlen = 0;
		return &item->h;
	}
	return NULL;
};

static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
{
	return hash_str(key->hostname, NFS_DNS_HASHBITS);
}

static void nfs_dns_request(struct cache_detail *cd,
		struct cache_head *ch,
		char **bpp, int *blen)
{
	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);

	qword_add(bpp, blen, key->hostname);
	(*bpp)[-1] = '\n';
}

static int nfs_dns_upcall(struct cache_detail *cd,
		struct cache_head *ch)
{
	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
	int ret;

	ret = nfs_cache_upcall(cd, key->hostname);
	if (ret)
		ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request);
	return ret;
}

static int nfs_dns_match(struct cache_head *ca,
		struct cache_head *cb)
{
	struct nfs_dns_ent *a;
	struct nfs_dns_ent *b;

	a = container_of(ca, struct nfs_dns_ent, h);
	b = container_of(cb, struct nfs_dns_ent, h);

	if (a->namelen == 0 || a->namelen != b->namelen)
		return 0;
	return memcmp(a->hostname, b->hostname, a->namelen) == 0;
}

static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd,
		struct cache_head *h)
{
	struct nfs_dns_ent *item;
	long ttl;

	if (h == NULL) {
		seq_puts(m, "# ip address      hostname        ttl\n");
		return 0;
	}
	item = container_of(h, struct nfs_dns_ent, h);
	ttl = item->h.expiry_time - seconds_since_boot();
	if (ttl < 0)
		ttl = 0;

	if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
		char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];

		rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
		seq_printf(m, "%15s ", buf);
	} else
		seq_puts(m, "<none>          ");
	seq_printf(m, "%15s %ld\n", item->hostname, ttl);
	return 0;
}

static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd,
		struct nfs_dns_ent *key)
{
	struct cache_head *ch;

	ch = sunrpc_cache_lookup(cd,
			&key->h,
			nfs_dns_hash(key));
	if (!ch)
		return NULL;
	return container_of(ch, struct nfs_dns_ent, h);
}

static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd,
		struct nfs_dns_ent *new,
		struct nfs_dns_ent *key)
{
	struct cache_head *ch;

	ch = sunrpc_cache_update(cd,
			&new->h, &key->h,
			nfs_dns_hash(key));
	if (!ch)
		return NULL;
	return container_of(ch, struct nfs_dns_ent, h);
}

static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
{
	char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
	struct nfs_dns_ent key, *item;
	unsigned long ttl;
	ssize_t len;
	int ret = -EINVAL;

	if (buf[buflen-1] != '\n')
		goto out;
	buf[buflen-1] = '\0';

	len = qword_get(&buf, buf1, sizeof(buf1));
	if (len <= 0)
		goto out;
	key.addrlen = rpc_pton(cd->net, buf1, len,
			(struct sockaddr *)&key.addr,
			sizeof(key.addr));

	len = qword_get(&buf, buf1, sizeof(buf1));
	if (len <= 0)
		goto out;

	key.hostname = buf1;
	key.namelen = len;
	memset(&key.h, 0, sizeof(key.h));

	ttl = get_expiry(&buf);
	if (ttl == 0)
		goto out;
	key.h.expiry_time = ttl + seconds_since_boot();

	ret = -ENOMEM;
	item = nfs_dns_lookup(cd, &key);
	if (item == NULL)
		goto out;

	if (key.addrlen == 0)
		set_bit(CACHE_NEGATIVE, &key.h.flags);

	item = nfs_dns_update(cd, &key, item);
	if (item == NULL)
		goto out;

	ret = 0;
	cache_put(&item->h, cd);
out:
	return ret;
}

static int do_cache_lookup(struct cache_detail *cd,
		struct nfs_dns_ent *key,
		struct nfs_dns_ent **item,
		struct nfs_cache_defer_req *dreq)
{
	int ret = -ENOMEM;

	*item = nfs_dns_lookup(cd, key);
	if (*item) {
		ret = cache_check(cd, &(*item)->h, &dreq->req);
		if (ret)
			*item = NULL;
	}
	return ret;
}

static int do_cache_lookup_nowait(struct cache_detail *cd,
		struct nfs_dns_ent *key,
		struct nfs_dns_ent **item)
{
	int ret = -ENOMEM;

	*item = nfs_dns_lookup(cd, key);
	if (!*item)
		goto out_err;
	ret = -ETIMEDOUT;
	if (!test_bit(CACHE_VALID, &(*item)->h.flags)
			|| (*item)->h.expiry_time < seconds_since_boot()
			|| cd->flush_time > (*item)->h.last_refresh)
		goto out_put;
	ret = -ENOENT;
	if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
		goto out_put;
	return 0;
out_put:
	cache_put(&(*item)->h, cd);
out_err:
	*item = NULL;
	return ret;
}

static int do_cache_lookup_wait(struct cache_detail *cd,
		struct nfs_dns_ent *key,
		struct nfs_dns_ent **item)
{
	struct nfs_cache_defer_req *dreq;
	int ret = -ENOMEM;

	dreq = nfs_cache_defer_req_alloc();
	if (!dreq)
		goto out;
	ret = do_cache_lookup(cd, key, item, dreq);
	if (ret == -EAGAIN) {
		ret = nfs_cache_wait_for_upcall(dreq);
		if (!ret)
			ret = do_cache_lookup_nowait(cd, key, item);
	}
	nfs_cache_defer_req_put(dreq);
out:
	return ret;
}

ssize_t nfs_dns_resolve_name(struct net *net, char *name,
		size_t namelen, struct sockaddr *sa, size_t salen)
{
	struct nfs_dns_ent key = {
		.hostname = name,
		.namelen = namelen,
	};
	struct nfs_dns_ent *item = NULL;
	ssize_t ret;
	struct nfs_net *nn = net_generic(net, nfs_net_id);

	ret = do_cache_lookup_wait(nn->nfs_dns_resolve, &key, &item);
	if (ret == 0) {
		if (salen >= item->addrlen) {
			memcpy(sa, &item->addr, item->addrlen);
			ret = item->addrlen;
		} else
			ret = -EOVERFLOW;
		cache_put(&item->h, nn->nfs_dns_resolve);
	} else if (ret == -ENOENT)
		ret = -ESRCH;
	return ret;
}

int nfs_dns_resolver_cache_init(struct net *net)
{
	int err = -ENOMEM;
	struct nfs_net *nn = net_generic(net, nfs_net_id);
	struct cache_detail *cd;
	struct cache_head **tbl;

	cd = kzalloc(sizeof(struct cache_detail), GFP_KERNEL);
	if (cd == NULL)
		goto err_cd;

	tbl = kzalloc(NFS_DNS_HASHTBL_SIZE * sizeof(struct cache_head *),
			GFP_KERNEL);
	if (tbl == NULL)
		goto err_tbl;

	cd->owner = THIS_MODULE,
	cd->hash_size = NFS_DNS_HASHTBL_SIZE,
	cd->hash_table = tbl,
	cd->name = "dns_resolve",
	cd->cache_put = nfs_dns_ent_put,
	cd->cache_upcall = nfs_dns_upcall,
	cd->cache_parse = nfs_dns_parse,
	cd->cache_show = nfs_dns_show,
	cd->match = nfs_dns_match,
	cd->init = nfs_dns_ent_init,
	cd->update = nfs_dns_ent_update,
	cd->alloc = nfs_dns_ent_alloc,

	nfs_cache_init(cd);
	err = nfs_cache_register_net(net, cd);
	if (err)
		goto err_reg;
	nn->nfs_dns_resolve = cd;
	return 0;

err_reg:
	nfs_cache_destroy(cd);
	kfree(cd->hash_table);
err_tbl:
	kfree(cd);
err_cd:
	return err;
}

void nfs_dns_resolver_cache_destroy(struct net *net)
{
	struct nfs_net *nn = net_generic(net, nfs_net_id);
	struct cache_detail *cd = nn->nfs_dns_resolve;

	nfs_cache_unregister_net(net, cd);
	nfs_cache_destroy(cd);
	kfree(cd->hash_table);
	kfree(cd);
}

static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
			   void *ptr)
{
	struct super_block *sb = ptr;
	struct net *net = sb->s_fs_info;
	struct nfs_net *nn = net_generic(net, nfs_net_id);
	struct cache_detail *cd = nn->nfs_dns_resolve;
	int ret = 0;

	if (cd == NULL)
		return 0;

	if (!try_module_get(THIS_MODULE))
		return 0;

	switch (event) {
	case RPC_PIPEFS_MOUNT:
		ret = nfs_cache_register_sb(sb, cd);
		break;
	case RPC_PIPEFS_UMOUNT:
		nfs_cache_unregister_sb(sb, cd);
		break;
	default:
		ret = -ENOTSUPP;
		break;
	}
	module_put(THIS_MODULE);
	return ret;
}

static struct notifier_block nfs_dns_resolver_block = {
	.notifier_call	= rpc_pipefs_event,
};

int nfs_dns_resolver_init(void)
{
	return rpc_pipefs_notifier_register(&nfs_dns_resolver_block);
}

void nfs_dns_resolver_destroy(void)
{
	rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block);
}
#endif
Commit	Line	Data
e571cbf1 TM	1	/*
	2	* linux/fs/nfs/dns_resolve.c
	3	*
	4	* Copyright (c) 2009 Trond Myklebust <Trond.Myklebust@netapp.com>
	5	*
	6	* Resolves DNS hostnames into valid ip addresses
	7	*/
	8
c2e8139c BS	9	#ifdef CONFIG_NFS_USE_KERNEL_DNS
	10
	11	#include <linux/sunrpc/clnt.h>
	12	#include <linux/dns_resolver.h>
17280175	13	#include "dns_resolve.h"
c2e8139c	14
1b340d01	15	ssize_t nfs_dns_resolve_name(struct net net, char name, size_t namelen,
c2e8139c BS	16	struct sockaddr *sa, size_t salen)
	17	{
	18	ssize_t ret;
	19	char *ip_addr = NULL;
	20	int ip_len;
	21
	22	ip_len = dns_query(NULL, name, namelen, NULL, &ip_addr, NULL);
	23	if (ip_len > 0)
bc224f53	24	ret = rpc_pton(net, ip_addr, ip_len, sa, salen);
c2e8139c BS	25	else
	26	ret = -ESRCH;
	27	kfree(ip_addr);
	28	return ret;
	29	}
	30
	31	#else
	32
e571cbf1 TM	33	#include <linux/hash.h>
	34	#include <linux/string.h>
	35	#include <linux/kmod.h>
5a0e3ad6	36	#include <linux/slab.h>
e571cbf1 TM	37	#include <linux/module.h>
	38	#include <linux/socket.h>
	39	#include <linux/seq_file.h>
	40	#include <linux/inet.h>
	41	#include <linux/sunrpc/clnt.h>
	42	#include <linux/sunrpc/cache.h>
	43	#include <linux/sunrpc/svcauth.h>
9df69c81	44	#include <linux/sunrpc/rpc_pipe_fs.h>
e571cbf1 TM	45
	46	#include "dns_resolve.h"
	47	#include "cache_lib.h"
1b340d01	48	#include "netns.h"
e571cbf1 TM	49
	50	#define NFS_DNS_HASHBITS 4
	51	#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
	52
e571cbf1 TM	53	struct nfs_dns_ent {
	54	struct cache_head h;
	55
	56	char *hostname;
	57	size_t namelen;
	58
	59	struct sockaddr_storage addr;
	60	size_t addrlen;
	61	};
	62
	63
ebed9203 TM	64	static void nfs_dns_ent_update(struct cache_head *cnew,
	65	struct cache_head *ckey)
	66	{
	67	struct nfs_dns_ent *new;
	68	struct nfs_dns_ent *key;
	69
	70	new = container_of(cnew, struct nfs_dns_ent, h);
	71	key = container_of(ckey, struct nfs_dns_ent, h);
	72
	73	memcpy(&new->addr, &key->addr, key->addrlen);
	74	new->addrlen = key->addrlen;
	75	}
	76
e571cbf1 TM	77	static void nfs_dns_ent_init(struct cache_head *cnew,
	78	struct cache_head *ckey)
	79	{
	80	struct nfs_dns_ent *new;
	81	struct nfs_dns_ent *key;
	82
	83	new = container_of(cnew, struct nfs_dns_ent, h);
	84	key = container_of(ckey, struct nfs_dns_ent, h);
	85
	86	kfree(new->hostname);
	87	new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
	88	if (new->hostname) {
	89	new->namelen = key->namelen;
ebed9203	90	nfs_dns_ent_update(cnew, ckey);
e571cbf1 TM	91	} else {
	92	new->namelen = 0;
	93	new->addrlen = 0;
	94	}
	95	}
	96
	97	static void nfs_dns_ent_put(struct kref *ref)
	98	{
	99	struct nfs_dns_ent *item;
	100
	101	item = container_of(ref, struct nfs_dns_ent, h.ref);
	102	kfree(item->hostname);
	103	kfree(item);
	104	}
	105
	106	static struct cache_head *nfs_dns_ent_alloc(void)
	107	{
	108	struct nfs_dns_ent item = kmalloc(sizeof(item), GFP_KERNEL);
	109
	110	if (item != NULL) {
	111	item->hostname = NULL;
	112	item->namelen = 0;
	113	item->addrlen = 0;
	114	return &item->h;
	115	}
	116	return NULL;
	117	};
	118
	119	static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
	120	{
	121	return hash_str(key->hostname, NFS_DNS_HASHBITS);
	122	}
	123
	124	static void nfs_dns_request(struct cache_detail *cd,
	125	struct cache_head *ch,
	126	char *bpp, int blen)
	127	{
	128	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
	129
	130	qword_add(bpp, blen, key->hostname);
	131	(*bpp)[-1] = '\n';
	132	}
	133
	134	static int nfs_dns_upcall(struct cache_detail *cd,
	135	struct cache_head *ch)
	136	{
	137	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
	138	int ret;
	139
	140	ret = nfs_cache_upcall(cd, key->hostname);
	141	if (ret)
	142	ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request);
	143	return ret;
	144	}
	145
	146	static int nfs_dns_match(struct cache_head *ca,
	147	struct cache_head *cb)
	148	{
	149	struct nfs_dns_ent *a;
	150	struct nfs_dns_ent *b;
	151
	152	a = container_of(ca, struct nfs_dns_ent, h);
	153	b = container_of(cb, struct nfs_dns_ent, h);
	154
155	if (a->namelen == 0 \|\| a->namelen != b->namelen)
156	return 0;
157	return memcmp(a->hostname, b->hostname, a->namelen) == 0;
158	}
159
160	static int nfs_dns_show(struct seq_file m, struct cache_detail cd,
161	struct cache_head *h)
162	{
163	struct nfs_dns_ent *item;
164	long ttl;
165
166	if (h == NULL) {
167	seq_puts(m, "# ip address hostname ttl\n");
168	return 0;
169	}
170	item = container_of(h, struct nfs_dns_ent, h);
c5b29f88	171	ttl = item->h.expiry_time - seconds_since_boot();
e571cbf1 TM	172	if (ttl < 0)
	173	ttl = 0;
	174
	175	if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
	176	char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
	177
	178	rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
	179	seq_printf(m, "%15s ", buf);
	180	} else
	181	seq_puts(m, "<none> ");
	182	seq_printf(m, "%15s %ld\n", item->hostname, ttl);
	183	return 0;
	184	}
	185
0a6566ec	186	static struct nfs_dns_ent nfs_dns_lookup(struct cache_detail cd,
e571cbf1 TM	187	struct nfs_dns_ent *key)
	188	{
	189	struct cache_head *ch;
	190
	191	ch = sunrpc_cache_lookup(cd,
	192	&key->h,
	193	nfs_dns_hash(key));
	194	if (!ch)
	195	return NULL;
	196	return container_of(ch, struct nfs_dns_ent, h);
	197	}
	198
0a6566ec	199	static struct nfs_dns_ent nfs_dns_update(struct cache_detail cd,
e571cbf1 TM	200	struct nfs_dns_ent *new,
	201	struct nfs_dns_ent *key)
	202	{
	203	struct cache_head *ch;
	204
	205	ch = sunrpc_cache_update(cd,
	206	&new->h, &key->h,
	207	nfs_dns_hash(key));
	208	if (!ch)
	209	return NULL;
	210	return container_of(ch, struct nfs_dns_ent, h);
	211	}
	212
	213	static int nfs_dns_parse(struct cache_detail cd, char buf, int buflen)
	214	{
	215	char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
	216	struct nfs_dns_ent key, *item;
	217	unsigned long ttl;
	218	ssize_t len;
	219	int ret = -EINVAL;
	220
	221	if (buf[buflen-1] != '\n')
	222	goto out;
	223	buf[buflen-1] = '\0';
	224
	225	len = qword_get(&buf, buf1, sizeof(buf1));
	226	if (len <= 0)
	227	goto out;
599ec129	228	key.addrlen = rpc_pton(cd->net, buf1, len,
e571cbf1 TM	229	(struct sockaddr *)&key.addr,
	230	sizeof(key.addr));
	231
	232	len = qword_get(&buf, buf1, sizeof(buf1));
	233	if (len <= 0)
	234	goto out;
	235
	236	key.hostname = buf1;
	237	key.namelen = len;
	238	memset(&key.h, 0, sizeof(key.h));
	239
	240	ttl = get_expiry(&buf);
	241	if (ttl == 0)
	242	goto out;
c5b29f88	243	key.h.expiry_time = ttl + seconds_since_boot();
e571cbf1 TM	244
	245	ret = -ENOMEM;
	246	item = nfs_dns_lookup(cd, &key);
	247	if (item == NULL)
	248	goto out;
	249
	250	if (key.addrlen == 0)
	251	set_bit(CACHE_NEGATIVE, &key.h.flags);
	252
	253	item = nfs_dns_update(cd, &key, item);
	254	if (item == NULL)
	255	goto out;
	256
	257	ret = 0;
	258	cache_put(&item->h, cd);
	259	out:
	260	return ret;
	261	}
	262
e571cbf1 TM	263	static int do_cache_lookup(struct cache_detail *cd,
	264	struct nfs_dns_ent *key,
	265	struct nfs_dns_ent **item,
	266	struct nfs_cache_defer_req *dreq)
	267	{
	268	int ret = -ENOMEM;
	269
	270	*item = nfs_dns_lookup(cd, key);
	271	if (*item) {
	272	ret = cache_check(cd, &(*item)->h, &dreq->req);
	273	if (ret)
	274	*item = NULL;
	275	}
	276	return ret;
	277	}
	278
	279	static int do_cache_lookup_nowait(struct cache_detail *cd,
	280	struct nfs_dns_ent *key,
	281	struct nfs_dns_ent **item)
	282	{
	283	int ret = -ENOMEM;
	284
	285	*item = nfs_dns_lookup(cd, key);
	286	if (!*item)
	287	goto out_err;
	288	ret = -ETIMEDOUT;
	289	if (!test_bit(CACHE_VALID, &(*item)->h.flags)
c5b29f88	290	\|\| (*item)->h.expiry_time < seconds_since_boot()
e571cbf1 TM	291	\|\| cd->flush_time > (*item)->h.last_refresh)
	292	goto out_put;
	293	ret = -ENOENT;
	294	if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
	295	goto out_put;
	296	return 0;
	297	out_put:
	298	cache_put(&(*item)->h, cd);
	299	out_err:
	300	*item = NULL;
	301	return ret;
	302	}
	303
	304	static int do_cache_lookup_wait(struct cache_detail *cd,
	305	struct nfs_dns_ent *key,
	306	struct nfs_dns_ent **item)
	307	{
	308	struct nfs_cache_defer_req *dreq;
	309	int ret = -ENOMEM;
	310
	311	dreq = nfs_cache_defer_req_alloc();
	312	if (!dreq)
	313	goto out;
	314	ret = do_cache_lookup(cd, key, item, dreq);
	315	if (ret == -EAGAIN) {
	316	ret = nfs_cache_wait_for_upcall(dreq);
	317	if (!ret)
	318	ret = do_cache_lookup_nowait(cd, key, item);
	319	}
	320	nfs_cache_defer_req_put(dreq);
	321	out:
	322	return ret;
	323	}
	324
1b340d01 SK	325	ssize_t nfs_dns_resolve_name(struct net net, char name,
1b340d01 SK	326	size_t namelen, struct sockaddr *sa, size_t salen)
e571cbf1 TM	327	{
	328	struct nfs_dns_ent key = {
	329	.hostname = name,
	330	.namelen = namelen,
	331	};
	332	struct nfs_dns_ent *item = NULL;
	333	ssize_t ret;
1b340d01	334	struct nfs_net *nn = net_generic(net, nfs_net_id);
e571cbf1	335
1b340d01	336	ret = do_cache_lookup_wait(nn->nfs_dns_resolve, &key, &item);
e571cbf1 TM	337	if (ret == 0) {
	338	if (salen >= item->addrlen) {
	339	memcpy(sa, &item->addr, item->addrlen);
	340	ret = item->addrlen;
	341	} else
	342	ret = -EOVERFLOW;
1b340d01	343	cache_put(&item->h, nn->nfs_dns_resolve);
e571cbf1 TM	344	} else if (ret == -ENOENT)
	345	ret = -ESRCH;
	346	return ret;
	347	}
	348
1b340d01	349	int nfs_dns_resolver_cache_init(struct net *net)
e571cbf1	350	{
1b340d01 SK	351	int err = -ENOMEM;
	352	struct nfs_net *nn = net_generic(net, nfs_net_id);
	353	struct cache_detail *cd;
	354	struct cache_head **tbl;
	355
	356	cd = kzalloc(sizeof(struct cache_detail), GFP_KERNEL);
	357	if (cd == NULL)
	358	goto err_cd;
	359
	360	tbl = kzalloc(NFS_DNS_HASHTBL_SIZE * sizeof(struct cache_head *),
	361	GFP_KERNEL);
	362	if (tbl == NULL)
	363	goto err_tbl;
	364
	365	cd->owner = THIS_MODULE,
	366	cd->hash_size = NFS_DNS_HASHTBL_SIZE,
	367	cd->hash_table = tbl,
	368	cd->name = "dns_resolve",
	369	cd->cache_put = nfs_dns_ent_put,
	370	cd->cache_upcall = nfs_dns_upcall,
	371	cd->cache_parse = nfs_dns_parse,
	372	cd->cache_show = nfs_dns_show,
	373	cd->match = nfs_dns_match,
	374	cd->init = nfs_dns_ent_init,
	375	cd->update = nfs_dns_ent_update,
	376	cd->alloc = nfs_dns_ent_alloc,
	377
	378	nfs_cache_init(cd);
	379	err = nfs_cache_register_net(net, cd);
	380	if (err)
	381	goto err_reg;
	382	nn->nfs_dns_resolve = cd;
	383	return 0;
9222b955	384
1b340d01 SK	385	err_reg:
	386	nfs_cache_destroy(cd);
	387	kfree(cd->hash_table);
	388	err_tbl:
	389	kfree(cd);
	390	err_cd:
	391	return err;
	392	}
	393
	394	void nfs_dns_resolver_cache_destroy(struct net *net)
	395	{
	396	struct nfs_net *nn = net_generic(net, nfs_net_id);
	397	struct cache_detail *cd = nn->nfs_dns_resolve;
	398
	399	nfs_cache_unregister_net(net, cd);
	400	nfs_cache_destroy(cd);
	401	kfree(cd->hash_table);
	402	kfree(cd);
	403	}
	404
9df69c81 SK	405	static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
	406	void *ptr)
	407	{
	408	struct super_block *sb = ptr;
	409	struct net *net = sb->s_fs_info;
	410	struct nfs_net *nn = net_generic(net, nfs_net_id);
	411	struct cache_detail *cd = nn->nfs_dns_resolve;
	412	int ret = 0;
	413
	414	if (cd == NULL)
	415	return 0;
	416
	417	if (!try_module_get(THIS_MODULE))
	418	return 0;
	419
	420	switch (event) {
	421	case RPC_PIPEFS_MOUNT:
	422	ret = nfs_cache_register_sb(sb, cd);
	423	break;
	424	case RPC_PIPEFS_UMOUNT:
	425	nfs_cache_unregister_sb(sb, cd);
	426	break;
	427	default:
	428	ret = -ENOTSUPP;
	429	break;
	430	}
	431	module_put(THIS_MODULE);
	432	return ret;
	433	}
	434
	435	static struct notifier_block nfs_dns_resolver_block = {
	436	.notifier_call = rpc_pipefs_event,
	437	};
	438
1b340d01 SK	439	int nfs_dns_resolver_init(void)
1b340d01 SK	440	{
9df69c81	441	return rpc_pipefs_notifier_register(&nfs_dns_resolver_block);
e571cbf1 TM	442	}
	443
	444	void nfs_dns_resolver_destroy(void)
	445	{
9df69c81	446	rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block);
e571cbf1	447	}
c2e8139c	448	#endif