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

/*
 * linux/fs/nfs/dns_resolve.c
 *
 * Copyright (c) 2009 Trond Myklebust <[email protected]>
 *
 * Resolves DNS hostnames into valid ip addresses
 */

#ifdef CONFIG_NFS_USE_KERNEL_DNS

#include <linux/module.h>
#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;
}
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/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 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);

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 <[email protected]>
	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 BS	12	#include <linux/sunrpc/clnt.h>
c2e8139c BS	13	#include <linux/dns_resolver.h>
17280175	14	#include "dns_resolve.h"
c2e8139c	15
1b340d01	16	ssize_t nfs_dns_resolve_name(struct net net, char name, size_t namelen,
c2e8139c BS	17	struct sockaddr *sa, size_t salen)
	18	{
	19	ssize_t ret;
	20	char *ip_addr = NULL;
	21	int ip_len;
	22
	23	ip_len = dns_query(NULL, name, namelen, NULL, &ip_addr, NULL);
	24	if (ip_len > 0)
bc224f53	25	ret = rpc_pton(net, ip_addr, ip_len, sa, salen);
c2e8139c BS	26	else
	27	ret = -ESRCH;
	28	kfree(ip_addr);
	29	return ret;
	30	}
89d77c8f	31	EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);
c2e8139c BS	32
	33	#else
	34
89d77c8f	35	#include <linux/module.h>
e571cbf1 TM	36	#include <linux/hash.h>
	37	#include <linux/string.h>
	38	#include <linux/kmod.h>
5a0e3ad6	39	#include <linux/slab.h>
e571cbf1 TM	40	#include <linux/module.h>
	41	#include <linux/socket.h>
	42	#include <linux/seq_file.h>
	43	#include <linux/inet.h>
	44	#include <linux/sunrpc/clnt.h>
	45	#include <linux/sunrpc/cache.h>
	46	#include <linux/sunrpc/svcauth.h>
9df69c81	47	#include <linux/sunrpc/rpc_pipe_fs.h>
e571cbf1 TM	48
	49	#include "dns_resolve.h"
	50	#include "cache_lib.h"
1b340d01	51	#include "netns.h"
e571cbf1 TM	52
	53	#define NFS_DNS_HASHBITS 4
	54	#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
	55
e571cbf1 TM	56	struct nfs_dns_ent {
	57	struct cache_head h;
	58
	59	char *hostname;
	60	size_t namelen;
	61
	62	struct sockaddr_storage addr;
	63	size_t addrlen;
	64	};
	65
	66
ebed9203 TM	67	static void nfs_dns_ent_update(struct cache_head *cnew,
	68	struct cache_head *ckey)
	69	{
	70	struct nfs_dns_ent *new;
	71	struct nfs_dns_ent *key;
	72
	73	new = container_of(cnew, struct nfs_dns_ent, h);
	74	key = container_of(ckey, struct nfs_dns_ent, h);
	75
	76	memcpy(&new->addr, &key->addr, key->addrlen);
	77	new->addrlen = key->addrlen;
	78	}
	79
e571cbf1 TM	80	static void nfs_dns_ent_init(struct cache_head *cnew,
	81	struct cache_head *ckey)
	82	{
	83	struct nfs_dns_ent *new;
	84	struct nfs_dns_ent *key;
	85
	86	new = container_of(cnew, struct nfs_dns_ent, h);
	87	key = container_of(ckey, struct nfs_dns_ent, h);
	88
	89	kfree(new->hostname);
	90	new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
	91	if (new->hostname) {
	92	new->namelen = key->namelen;
ebed9203	93	nfs_dns_ent_update(cnew, ckey);
e571cbf1 TM	94	} else {
	95	new->namelen = 0;
	96	new->addrlen = 0;
	97	}
	98	}
	99
	100	static void nfs_dns_ent_put(struct kref *ref)
	101	{
	102	struct nfs_dns_ent *item;
	103
	104	item = container_of(ref, struct nfs_dns_ent, h.ref);
	105	kfree(item->hostname);
	106	kfree(item);
	107	}
	108
	109	static struct cache_head *nfs_dns_ent_alloc(void)
	110	{
	111	struct nfs_dns_ent item = kmalloc(sizeof(item), GFP_KERNEL);
	112
	113	if (item != NULL) {
	114	item->hostname = NULL;
	115	item->namelen = 0;
	116	item->addrlen = 0;
	117	return &item->h;
	118	}
	119	return NULL;
	120	};
	121
	122	static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
	123	{
	124	return hash_str(key->hostname, NFS_DNS_HASHBITS);
	125	}
	126
	127	static void nfs_dns_request(struct cache_detail *cd,
	128	struct cache_head *ch,
	129	char *bpp, int blen)
	130	{
	131	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
	132
	133	qword_add(bpp, blen, key->hostname);
	134	(*bpp)[-1] = '\n';
	135	}
	136
	137	static int nfs_dns_upcall(struct cache_detail *cd,
	138	struct cache_head *ch)
	139	{
	140	struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
	141	int ret;
	142
	143	ret = nfs_cache_upcall(cd, key->hostname);
	144	if (ret)
	145	ret = sunrpc_cache_pipe_upcall(cd, ch, nfs_dns_request);
	146	return ret;
	147	}
	148
	149	static int nfs_dns_match(struct cache_head *ca,
	150	struct cache_head *cb)
	151	{
	152	struct nfs_dns_ent *a;
	153	struct nfs_dns_ent *b;
	154
	155	a = container_of(ca, struct nfs_dns_ent, h);
	156	b = container_of(cb, struct nfs_dns_ent, h);
	157
158	if (a->namelen == 0 \|\| a->namelen != b->namelen)
159	return 0;
160	return memcmp(a->hostname, b->hostname, a->namelen) == 0;
161	}
162
163	static int nfs_dns_show(struct seq_file m, struct cache_detail cd,
164	struct cache_head *h)
165	{
166	struct nfs_dns_ent *item;
167	long ttl;
168
169	if (h == NULL) {
170	seq_puts(m, "# ip address hostname ttl\n");
171	return 0;
172	}
173	item = container_of(h, struct nfs_dns_ent, h);
c5b29f88	174	ttl = item->h.expiry_time - seconds_since_boot();
e571cbf1 TM	175	if (ttl < 0)
	176	ttl = 0;
	177
	178	if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
	179	char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
	180
	181	rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
	182	seq_printf(m, "%15s ", buf);
	183	} else
	184	seq_puts(m, "<none> ");
	185	seq_printf(m, "%15s %ld\n", item->hostname, ttl);
	186	return 0;
	187	}
	188
0a6566ec	189	static struct nfs_dns_ent nfs_dns_lookup(struct cache_detail cd,
e571cbf1 TM	190	struct nfs_dns_ent *key)
	191	{
	192	struct cache_head *ch;
	193
	194	ch = sunrpc_cache_lookup(cd,
	195	&key->h,
	196	nfs_dns_hash(key));
	197	if (!ch)
	198	return NULL;
	199	return container_of(ch, struct nfs_dns_ent, h);
	200	}
	201
0a6566ec	202	static struct nfs_dns_ent nfs_dns_update(struct cache_detail cd,
e571cbf1 TM	203	struct nfs_dns_ent *new,
	204	struct nfs_dns_ent *key)
	205	{
	206	struct cache_head *ch;
	207
	208	ch = sunrpc_cache_update(cd,
	209	&new->h, &key->h,
	210	nfs_dns_hash(key));
	211	if (!ch)
	212	return NULL;
	213	return container_of(ch, struct nfs_dns_ent, h);
	214	}
	215
	216	static int nfs_dns_parse(struct cache_detail cd, char buf, int buflen)
	217	{
	218	char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
	219	struct nfs_dns_ent key, *item;
8d96b106	220	unsigned int ttl;
e571cbf1 TM	221	ssize_t len;
	222	int ret = -EINVAL;
	223
	224	if (buf[buflen-1] != '\n')
	225	goto out;
	226	buf[buflen-1] = '\0';
	227
	228	len = qword_get(&buf, buf1, sizeof(buf1));
	229	if (len <= 0)
	230	goto out;
599ec129	231	key.addrlen = rpc_pton(cd->net, buf1, len,
e571cbf1 TM	232	(struct sockaddr *)&key.addr,
	233	sizeof(key.addr));
	234
	235	len = qword_get(&buf, buf1, sizeof(buf1));
	236	if (len <= 0)
	237	goto out;
	238
	239	key.hostname = buf1;
	240	key.namelen = len;
	241	memset(&key.h, 0, sizeof(key.h));
	242
8d96b106 N	243	if (get_uint(&buf, &ttl) < 0)
8d96b106 N	244	goto out;
e571cbf1 TM	245	if (ttl == 0)
e571cbf1 TM	246	goto out;
c5b29f88	247	key.h.expiry_time = ttl + seconds_since_boot();
e571cbf1 TM	248
	249	ret = -ENOMEM;
	250	item = nfs_dns_lookup(cd, &key);
	251	if (item == NULL)
	252	goto out;
	253
	254	if (key.addrlen == 0)
	255	set_bit(CACHE_NEGATIVE, &key.h.flags);
	256
	257	item = nfs_dns_update(cd, &key, item);
	258	if (item == NULL)
	259	goto out;
	260
	261	ret = 0;
	262	cache_put(&item->h, cd);
	263	out:
	264	return ret;
	265	}
	266
e571cbf1 TM	267	static int do_cache_lookup(struct cache_detail *cd,
	268	struct nfs_dns_ent *key,
	269	struct nfs_dns_ent **item,
	270	struct nfs_cache_defer_req *dreq)
	271	{
	272	int ret = -ENOMEM;
	273
	274	*item = nfs_dns_lookup(cd, key);
	275	if (*item) {
	276	ret = cache_check(cd, &(*item)->h, &dreq->req);
	277	if (ret)
	278	*item = NULL;
	279	}
	280	return ret;
	281	}
	282
	283	static int do_cache_lookup_nowait(struct cache_detail *cd,
	284	struct nfs_dns_ent *key,
	285	struct nfs_dns_ent **item)
	286	{
	287	int ret = -ENOMEM;
	288
	289	*item = nfs_dns_lookup(cd, key);
	290	if (!*item)
	291	goto out_err;
	292	ret = -ETIMEDOUT;
	293	if (!test_bit(CACHE_VALID, &(*item)->h.flags)
c5b29f88	294	\|\| (*item)->h.expiry_time < seconds_since_boot()
e571cbf1 TM	295	\|\| cd->flush_time > (*item)->h.last_refresh)
	296	goto out_put;
	297	ret = -ENOENT;
	298	if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
	299	goto out_put;
	300	return 0;
	301	out_put:
	302	cache_put(&(*item)->h, cd);
	303	out_err:
	304	*item = NULL;
	305	return ret;
	306	}
	307
	308	static int do_cache_lookup_wait(struct cache_detail *cd,
	309	struct nfs_dns_ent *key,
	310	struct nfs_dns_ent **item)
	311	{
	312	struct nfs_cache_defer_req *dreq;
	313	int ret = -ENOMEM;
	314
	315	dreq = nfs_cache_defer_req_alloc();
	316	if (!dreq)
	317	goto out;
	318	ret = do_cache_lookup(cd, key, item, dreq);
	319	if (ret == -EAGAIN) {
	320	ret = nfs_cache_wait_for_upcall(dreq);
	321	if (!ret)
	322	ret = do_cache_lookup_nowait(cd, key, item);
	323	}
	324	nfs_cache_defer_req_put(dreq);
	325	out:
	326	return ret;
	327	}
	328
1b340d01 SK	329	ssize_t nfs_dns_resolve_name(struct net net, char name,
1b340d01 SK	330	size_t namelen, struct sockaddr *sa, size_t salen)
e571cbf1 TM	331	{
	332	struct nfs_dns_ent key = {
	333	.hostname = name,
	334	.namelen = namelen,
	335	};
	336	struct nfs_dns_ent *item = NULL;
	337	ssize_t ret;
1b340d01	338	struct nfs_net *nn = net_generic(net, nfs_net_id);
e571cbf1	339
1b340d01	340	ret = do_cache_lookup_wait(nn->nfs_dns_resolve, &key, &item);
e571cbf1 TM	341	if (ret == 0) {
	342	if (salen >= item->addrlen) {
	343	memcpy(sa, &item->addr, item->addrlen);
	344	ret = item->addrlen;
	345	} else
	346	ret = -EOVERFLOW;
1b340d01	347	cache_put(&item->h, nn->nfs_dns_resolve);
e571cbf1 TM	348	} else if (ret == -ENOENT)
	349	ret = -ESRCH;
	350	return ret;
	351	}
89d77c8f	352	EXPORT_SYMBOL_GPL(nfs_dns_resolve_name);
e571cbf1	353
1b340d01	354	int nfs_dns_resolver_cache_init(struct net *net)
e571cbf1	355	{
1b340d01 SK	356	int err = -ENOMEM;
	357	struct nfs_net *nn = net_generic(net, nfs_net_id);
	358	struct cache_detail *cd;
	359	struct cache_head **tbl;
	360
	361	cd = kzalloc(sizeof(struct cache_detail), GFP_KERNEL);
	362	if (cd == NULL)
	363	goto err_cd;
	364
	365	tbl = kzalloc(NFS_DNS_HASHTBL_SIZE * sizeof(struct cache_head *),
	366	GFP_KERNEL);
	367	if (tbl == NULL)
	368	goto err_tbl;
	369
	370	cd->owner = THIS_MODULE,
	371	cd->hash_size = NFS_DNS_HASHTBL_SIZE,
	372	cd->hash_table = tbl,
	373	cd->name = "dns_resolve",
	374	cd->cache_put = nfs_dns_ent_put,
	375	cd->cache_upcall = nfs_dns_upcall,
	376	cd->cache_parse = nfs_dns_parse,
	377	cd->cache_show = nfs_dns_show,
	378	cd->match = nfs_dns_match,
	379	cd->init = nfs_dns_ent_init,
	380	cd->update = nfs_dns_ent_update,
	381	cd->alloc = nfs_dns_ent_alloc,
	382
	383	nfs_cache_init(cd);
	384	err = nfs_cache_register_net(net, cd);
	385	if (err)
	386	goto err_reg;
	387	nn->nfs_dns_resolve = cd;
	388	return 0;
9222b955	389
1b340d01 SK	390	err_reg:
	391	nfs_cache_destroy(cd);
	392	kfree(cd->hash_table);
	393	err_tbl:
	394	kfree(cd);
	395	err_cd:
	396	return err;
	397	}
	398
	399	void nfs_dns_resolver_cache_destroy(struct net *net)
	400	{
	401	struct nfs_net *nn = net_generic(net, nfs_net_id);
	402	struct cache_detail *cd = nn->nfs_dns_resolve;
	403
	404	nfs_cache_unregister_net(net, cd);
	405	nfs_cache_destroy(cd);
	406	kfree(cd->hash_table);
	407	kfree(cd);
	408	}
	409
9df69c81 SK	410	static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
	411	void *ptr)
	412	{
	413	struct super_block *sb = ptr;
	414	struct net *net = sb->s_fs_info;
	415	struct nfs_net *nn = net_generic(net, nfs_net_id);
	416	struct cache_detail *cd = nn->nfs_dns_resolve;
	417	int ret = 0;
	418
	419	if (cd == NULL)
	420	return 0;
	421
	422	if (!try_module_get(THIS_MODULE))
	423	return 0;
	424
	425	switch (event) {
	426	case RPC_PIPEFS_MOUNT:
	427	ret = nfs_cache_register_sb(sb, cd);
	428	break;
	429	case RPC_PIPEFS_UMOUNT:
	430	nfs_cache_unregister_sb(sb, cd);
	431	break;
	432	default:
	433	ret = -ENOTSUPP;
	434	break;
	435	}
	436	module_put(THIS_MODULE);
	437	return ret;
	438	}
	439
	440	static struct notifier_block nfs_dns_resolver_block = {
	441	.notifier_call = rpc_pipefs_event,
	442	};
	443
1b340d01 SK	444	int nfs_dns_resolver_init(void)
1b340d01 SK	445	{
9df69c81	446	return rpc_pipefs_notifier_register(&nfs_dns_resolver_block);
e571cbf1 TM	447	}
	448
	449	void nfs_dns_resolver_destroy(void)
	450	{
9df69c81	451	rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block);
e571cbf1	452	}
c2e8139c	453	#endif