[deliverable/linux.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>

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