[mirror_ubuntu-artful-kernel.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/module.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/addr.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;
}
EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);

#else

#include <linux/module.h>
#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/addr.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);
	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 int 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));

	if (get_uint(&buf, &ttl) < 0)
		goto out;
	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;
}
EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);

static struct cache_detail nfs_dns_resolve_template = {
	.owner		= THIS_MODULE,
	.hash_size	= NFS_DNS_HASHTBL_SIZE,
	.name		= "dns_resolve",
	.cache_put	= nfs_dns_ent_put,
	.cache_upcall	= nfs_dns_upcall,
	.cache_request	= nfs_dns_request,
	.cache_parse	= nfs_dns_parse,
	.cache_show	= nfs_dns_show,
	.match		= nfs_dns_match,
	.init		= nfs_dns_ent_init,
	.update		= nfs_dns_ent_update,
	.alloc		= nfs_dns_ent_alloc,
};


int nfs_dns_resolver_cache_init(struct net *net)
{
	int err;
	struct nfs_net *nn = net_generic(net, nfs_net_id);

	nn->nfs_dns_resolve = cache_create_net(&nfs_dns_resolve_template, net);
	if (IS_ERR(nn->nfs_dns_resolve))
		return PTR_ERR(nn->nfs_dns_resolve);

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

err_reg:
	cache_destroy_net(nn->nfs_dns_resolve, net);
	return err;
}

void nfs_dns_resolver_cache_destroy(struct net *net)
{
	struct nfs_net *nn = net_generic(net, nfs_net_id);

	nfs_cache_unregister_net(net, nn->nfs_dns_resolve);
	cache_destroy_net(nn->nfs_dns_resolve, net);
}

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
c2e8139c BS	10
89d77c8f	11	#include <linux/module.h>
c2e8139c	12	#include <linux/sunrpc/clnt.h>
5976687a	13	#include <linux/sunrpc/addr.h>
c2e8139c	14	#include <linux/dns_resolver.h>
17280175	15	#include "dns_resolve.h"
c2e8139c	16
1b340d01	17	ssize_t nfs_dns_resolve_name(struct net net, char name, size_t namelen,
c2e8139c BS	18	struct sockaddr *sa, size_t salen)
	19	{
	20	ssize_t ret;
	21	char *ip_addr = NULL;
	22	int ip_len;
	23
	24	ip_len = dns_query(NULL, name, namelen, NULL, &ip_addr, NULL);
	25	if (ip_len > 0)
bc224f53	26	ret = rpc_pton(net, ip_addr, ip_len, sa, salen);
c2e8139c BS	27	else
	28	ret = -ESRCH;
	29	kfree(ip_addr);
	30	return ret;
	31	}
89d77c8f	32	EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);
c2e8139c BS	33
	34	#else
	35
89d77c8f	36	#include <linux/module.h>
e571cbf1 TM	37	#include <linux/hash.h>
	38	#include <linux/string.h>
	39	#include <linux/kmod.h>
5a0e3ad6	40	#include <linux/slab.h>
e571cbf1 TM	41	#include <linux/module.h>
	42	#include <linux/socket.h>
	43	#include <linux/seq_file.h>
	44	#include <linux/inet.h>
	45	#include <linux/sunrpc/clnt.h>
5976687a	46	#include <linux/sunrpc/addr.h>
e571cbf1 TM	47	#include <linux/sunrpc/cache.h>
e571cbf1 TM	48	#include <linux/sunrpc/svcauth.h>
9df69c81	49	#include <linux/sunrpc/rpc_pipe_fs.h>
e571cbf1 TM	50
	51	#include "dns_resolve.h"
	52	#include "cache_lib.h"
1b340d01	53	#include "netns.h"
e571cbf1 TM	54
	55	#define NFS_DNS_HASHBITS 4
	56	#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
	57
e571cbf1 TM	58	struct nfs_dns_ent {
	59	struct cache_head h;
	60
	61	char *hostname;
	62	size_t namelen;
	63
	64	struct sockaddr_storage addr;
	65	size_t addrlen;
	66	};
	67
	68
ebed9203 TM	69	static void nfs_dns_ent_update(struct cache_head *cnew,
	70	struct cache_head *ckey)
	71	{
	72	struct nfs_dns_ent *new;
	73	struct nfs_dns_ent *key;
	74
	75	new = container_of(cnew, struct nfs_dns_ent, h);
	76	key = container_of(ckey, struct nfs_dns_ent, h);
	77
	78	memcpy(&new->addr, &key->addr, key->addrlen);
	79	new->addrlen = key->addrlen;
	80	}
	81
e571cbf1 TM	82	static void nfs_dns_ent_init(struct cache_head *cnew,
	83	struct cache_head *ckey)
	84	{
	85	struct nfs_dns_ent *new;
	86	struct nfs_dns_ent *key;
	87
	88	new = container_of(cnew, struct nfs_dns_ent, h);
	89	key = container_of(ckey, struct nfs_dns_ent, h);
	90
	91	kfree(new->hostname);
	92	new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
	93	if (new->hostname) {
	94	new->namelen = key->namelen;
ebed9203	95	nfs_dns_ent_update(cnew, ckey);
e571cbf1 TM	96	} else {
	97	new->namelen = 0;
	98	new->addrlen = 0;
	99	}
	100	}
	101
	102	static void nfs_dns_ent_put(struct kref *ref)
	103	{
	104	struct nfs_dns_ent *item;
	105
	106	item = container_of(ref, struct nfs_dns_ent, h.ref);
	107	kfree(item->hostname);
	108	kfree(item);
	109	}
	110
	111	static struct cache_head *nfs_dns_ent_alloc(void)
	112	{
	113	struct nfs_dns_ent item = kmalloc(sizeof(item), GFP_KERNEL);
	114
	115	if (item != NULL) {
	116	item->hostname = NULL;
	117	item->namelen = 0;
	118	item->addrlen = 0;
	119	return &item->h;
	120	}
	121	return NULL;
	122	};
	123
	124	static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
	125	{
	126	return hash_str(key->hostname, NFS_DNS_HASHBITS);
	127	}
	128
	129	static void nfs_dns_request(struct cache_detail *cd,
	130	struct cache_head *ch,
	131	char *bpp, int blen)
	132	{
	133	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
	134
	135	qword_add(bpp, blen, key->hostname);
	136	(*bpp)[-1] = '\n';
	137	}
	138
	139	static int nfs_dns_upcall(struct cache_detail *cd,
	140	struct cache_head *ch)
	141	{
	142	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
	143	int ret;
	144
	145	ret = nfs_cache_upcall(cd, key->hostname);
	146	if (ret)
21cd1254	147	ret = sunrpc_cache_pipe_upcall(cd, ch);
e571cbf1 TM	148	return ret;
	149	}
	150
	151	static int nfs_dns_match(struct cache_head *ca,
	152	struct cache_head *cb)
	153	{
	154	struct nfs_dns_ent *a;
	155	struct nfs_dns_ent *b;
	156
	157	a = container_of(ca, struct nfs_dns_ent, h);
	158	b = container_of(cb, struct nfs_dns_ent, h);
	159
	160	if (a->namelen == 0 \|\| a->namelen != b->namelen)
	161	return 0;
	162	return memcmp(a->hostname, b->hostname, a->namelen) == 0;
	163	}
	164
	165	static int nfs_dns_show(struct seq_file m, struct cache_detail cd,
	166	struct cache_head *h)
	167	{
	168	struct nfs_dns_ent *item;
	169	long ttl;
	170
	171	if (h == NULL) {
	172	seq_puts(m, "# ip address hostname ttl\n");
	173	return 0;
	174	}
	175	item = container_of(h, struct nfs_dns_ent, h);
c5b29f88	176	ttl = item->h.expiry_time - seconds_since_boot();
e571cbf1 TM	177	if (ttl < 0)
	178	ttl = 0;
	179
	180	if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
	181	char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
	182
	183	rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
	184	seq_printf(m, "%15s ", buf);
	185	} else
	186	seq_puts(m, "<none> ");
	187	seq_printf(m, "%15s %ld\n", item->hostname, ttl);
	188	return 0;
	189	}
	190
0a6566ec	191	static struct nfs_dns_ent nfs_dns_lookup(struct cache_detail cd,
e571cbf1 TM	192	struct nfs_dns_ent *key)
	193	{
	194	struct cache_head *ch;
	195
	196	ch = sunrpc_cache_lookup(cd,
	197	&key->h,
	198	nfs_dns_hash(key));
	199	if (!ch)
	200	return NULL;
	201	return container_of(ch, struct nfs_dns_ent, h);
	202	}
	203
0a6566ec	204	static struct nfs_dns_ent nfs_dns_update(struct cache_detail cd,
e571cbf1 TM	205	struct nfs_dns_ent *new,
	206	struct nfs_dns_ent *key)
	207	{
	208	struct cache_head *ch;
	209
	210	ch = sunrpc_cache_update(cd,
	211	&new->h, &key->h,
	212	nfs_dns_hash(key));
	213	if (!ch)
	214	return NULL;
	215	return container_of(ch, struct nfs_dns_ent, h);
	216	}
	217
	218	static int nfs_dns_parse(struct cache_detail cd, char buf, int buflen)
	219	{
	220	char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
	221	struct nfs_dns_ent key, *item;
8d96b106	222	unsigned int ttl;
e571cbf1 TM	223	ssize_t len;
	224	int ret = -EINVAL;
	225
	226	if (buf[buflen-1] != '\n')
	227	goto out;
	228	buf[buflen-1] = '\0';
	229
	230	len = qword_get(&buf, buf1, sizeof(buf1));
	231	if (len <= 0)
	232	goto out;
599ec129	233	key.addrlen = rpc_pton(cd->net, buf1, len,
e571cbf1 TM	234	(struct sockaddr *)&key.addr,
	235	sizeof(key.addr));
	236
	237	len = qword_get(&buf, buf1, sizeof(buf1));
	238	if (len <= 0)
	239	goto out;
	240
	241	key.hostname = buf1;
	242	key.namelen = len;
	243	memset(&key.h, 0, sizeof(key.h));
	244
8d96b106 N	245	if (get_uint(&buf, &ttl) < 0)
8d96b106 N	246	goto out;
e571cbf1 TM	247	if (ttl == 0)
e571cbf1 TM	248	goto out;
c5b29f88	249	key.h.expiry_time = ttl + seconds_since_boot();
e571cbf1 TM	250
	251	ret = -ENOMEM;
	252	item = nfs_dns_lookup(cd, &key);
	253	if (item == NULL)
	254	goto out;
	255
	256	if (key.addrlen == 0)
	257	set_bit(CACHE_NEGATIVE, &key.h.flags);
	258
	259	item = nfs_dns_update(cd, &key, item);
	260	if (item == NULL)
	261	goto out;
	262
	263	ret = 0;
	264	cache_put(&item->h, cd);
	265	out:
	266	return ret;
	267	}
	268
e571cbf1 TM	269	static int do_cache_lookup(struct cache_detail *cd,
	270	struct nfs_dns_ent *key,
	271	struct nfs_dns_ent **item,
	272	struct nfs_cache_defer_req *dreq)
	273	{
	274	int ret = -ENOMEM;
	275
	276	*item = nfs_dns_lookup(cd, key);
	277	if (*item) {
	278	ret = cache_check(cd, &(*item)->h, &dreq->req);
	279	if (ret)
	280	*item = NULL;
	281	}
	282	return ret;
	283	}
	284
	285	static int do_cache_lookup_nowait(struct cache_detail *cd,
	286	struct nfs_dns_ent *key,
	287	struct nfs_dns_ent **item)
	288	{
	289	int ret = -ENOMEM;
	290
	291	*item = nfs_dns_lookup(cd, key);
	292	if (!*item)
	293	goto out_err;
	294	ret = -ETIMEDOUT;
	295	if (!test_bit(CACHE_VALID, &(*item)->h.flags)
c5b29f88	296	\|\| (*item)->h.expiry_time < seconds_since_boot()
e571cbf1 TM	297	\|\| cd->flush_time > (*item)->h.last_refresh)
	298	goto out_put;
	299	ret = -ENOENT;
	300	if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
	301	goto out_put;
	302	return 0;
	303	out_put:
	304	cache_put(&(*item)->h, cd);
	305	out_err:
	306	*item = NULL;
	307	return ret;
	308	}
	309
	310	static int do_cache_lookup_wait(struct cache_detail *cd,
	311	struct nfs_dns_ent *key,
	312	struct nfs_dns_ent **item)
	313	{
	314	struct nfs_cache_defer_req *dreq;
	315	int ret = -ENOMEM;
	316
	317	dreq = nfs_cache_defer_req_alloc();
	318	if (!dreq)
	319	goto out;
	320	ret = do_cache_lookup(cd, key, item, dreq);
	321	if (ret == -EAGAIN) {
	322	ret = nfs_cache_wait_for_upcall(dreq);
	323	if (!ret)
	324	ret = do_cache_lookup_nowait(cd, key, item);
	325	}
	326	nfs_cache_defer_req_put(dreq);
	327	out:
	328	return ret;
	329	}
	330
1b340d01 SK	331	ssize_t nfs_dns_resolve_name(struct net net, char name,
1b340d01 SK	332	size_t namelen, struct sockaddr *sa, size_t salen)
e571cbf1 TM	333	{
	334	struct nfs_dns_ent key = {
	335	.hostname = name,
	336	.namelen = namelen,
	337	};
	338	struct nfs_dns_ent *item = NULL;
	339	ssize_t ret;
1b340d01	340	struct nfs_net *nn = net_generic(net, nfs_net_id);
e571cbf1	341
1b340d01	342	ret = do_cache_lookup_wait(nn->nfs_dns_resolve, &key, &item);
e571cbf1 TM	343	if (ret == 0) {
	344	if (salen >= item->addrlen) {
	345	memcpy(sa, &item->addr, item->addrlen);
	346	ret = item->addrlen;
	347	} else
	348	ret = -EOVERFLOW;
1b340d01	349	cache_put(&item->h, nn->nfs_dns_resolve);
e571cbf1 TM	350	} else if (ret == -ENOENT)
	351	ret = -ESRCH;
	352	return ret;
	353	}
89d77c8f	354	EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);
e571cbf1	355
483479c2 SK	356	static struct cache_detail nfs_dns_resolve_template = {
	357	.owner = THIS_MODULE,
	358	.hash_size = NFS_DNS_HASHTBL_SIZE,
	359	.name = "dns_resolve",
	360	.cache_put = nfs_dns_ent_put,
	361	.cache_upcall = nfs_dns_upcall,
73fb847a	362	.cache_request = nfs_dns_request,
483479c2 SK	363	.cache_parse = nfs_dns_parse,
	364	.cache_show = nfs_dns_show,
	365	.match = nfs_dns_match,
	366	.init = nfs_dns_ent_init,
	367	.update = nfs_dns_ent_update,
	368	.alloc = nfs_dns_ent_alloc,
	369	};
	370
	371
1b340d01	372	int nfs_dns_resolver_cache_init(struct net *net)
e571cbf1	373	{
483479c2	374	int err;
1b340d01	375	struct nfs_net *nn = net_generic(net, nfs_net_id);
1b340d01	376
483479c2 SK	377	nn->nfs_dns_resolve = cache_create_net(&nfs_dns_resolve_template, net);
	378	if (IS_ERR(nn->nfs_dns_resolve))
	379	return PTR_ERR(nn->nfs_dns_resolve);
	380
483479c2	381	err = nfs_cache_register_net(net, nn->nfs_dns_resolve);
1b340d01 SK	382	if (err)
1b340d01 SK	383	goto err_reg;
1b340d01	384	return 0;
9222b955	385
1b340d01	386	err_reg:
483479c2	387	cache_destroy_net(nn->nfs_dns_resolve, net);
1b340d01 SK	388	return err;
	389	}
	390
	391	void nfs_dns_resolver_cache_destroy(struct net *net)
	392	{
	393	struct nfs_net *nn = net_generic(net, nfs_net_id);
1b340d01	394
462b8f6b	395	nfs_cache_unregister_net(net, nn->nfs_dns_resolve);
483479c2	396	cache_destroy_net(nn->nfs_dns_resolve, net);
1b340d01 SK	397	}
1b340d01 SK	398
9df69c81 SK	399	static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
	400	void *ptr)
	401	{
	402	struct super_block *sb = ptr;
	403	struct net *net = sb->s_fs_info;
	404	struct nfs_net *nn = net_generic(net, nfs_net_id);
	405	struct cache_detail *cd = nn->nfs_dns_resolve;
	406	int ret = 0;
	407
	408	if (cd == NULL)
	409	return 0;
	410
	411	if (!try_module_get(THIS_MODULE))
	412	return 0;
	413
	414	switch (event) {
	415	case RPC_PIPEFS_MOUNT:
	416	ret = nfs_cache_register_sb(sb, cd);
	417	break;
	418	case RPC_PIPEFS_UMOUNT:
	419	nfs_cache_unregister_sb(sb, cd);
	420	break;
	421	default:
	422	ret = -ENOTSUPP;
	423	break;
	424	}
	425	module_put(THIS_MODULE);
	426	return ret;
	427	}
	428
	429	static struct notifier_block nfs_dns_resolver_block = {
	430	.notifier_call = rpc_pipefs_event,
	431	};
	432
1b340d01 SK	433	int nfs_dns_resolver_init(void)
1b340d01 SK	434	{
9df69c81	435	return rpc_pipefs_notifier_register(&nfs_dns_resolver_block);
e571cbf1 TM	436	}
	437
	438	void nfs_dns_resolver_destroy(void)
	439	{
9df69c81	440	rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block);
e571cbf1	441	}
c2e8139c	442	#endif