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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
9#ifdef CONFIG_NFS_USE_KERNEL_DNS
10
11#include <linux/module.h>
12#include <linux/sunrpc/clnt.h>
13#include <linux/sunrpc/addr.h>
14#include <linux/dns_resolver.h>
15#include "dns_resolve.h"
16
17ssize_t nfs_dns_resolve_name(struct net *net, char *name, size_t namelen,
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)
26 ret = rpc_pton(net, ip_addr, ip_len, sa, salen);
27 else
28 ret = -ESRCH;
29 kfree(ip_addr);
30 return ret;
31}
32
33#else
34
35#include <linux/module.h>
36#include <linux/hash.h>
37#include <linux/string.h>
38#include <linux/kmod.h>
39#include <linux/slab.h>
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/addr.h>
46#include <linux/sunrpc/cache.h>
47#include <linux/sunrpc/svcauth.h>
48#include <linux/sunrpc/rpc_pipe_fs.h>
49#include <linux/nfs_fs.h>
50
51#include "nfs4_fs.h"
52#include "dns_resolve.h"
53#include "cache_lib.h"
54#include "netns.h"
55
56#define NFS_DNS_HASHBITS 4
57#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
58
59struct nfs_dns_ent {
60 struct cache_head h;
61
62 char *hostname;
63 size_t namelen;
64
65 struct sockaddr_storage addr;
66 size_t addrlen;
67};
68
69
70static void nfs_dns_ent_update(struct cache_head *cnew,
71 struct cache_head *ckey)
72{
73 struct nfs_dns_ent *new;
74 struct nfs_dns_ent *key;
75
76 new = container_of(cnew, struct nfs_dns_ent, h);
77 key = container_of(ckey, struct nfs_dns_ent, h);
78
79 memcpy(&new->addr, &key->addr, key->addrlen);
80 new->addrlen = key->addrlen;
81}
82
83static void nfs_dns_ent_init(struct cache_head *cnew,
84 struct cache_head *ckey)
85{
86 struct nfs_dns_ent *new;
87 struct nfs_dns_ent *key;
88
89 new = container_of(cnew, struct nfs_dns_ent, h);
90 key = container_of(ckey, struct nfs_dns_ent, h);
91
92 kfree(new->hostname);
93 new->hostname = kstrndup(key->hostname, key->namelen, GFP_KERNEL);
94 if (new->hostname) {
95 new->namelen = key->namelen;
96 nfs_dns_ent_update(cnew, ckey);
97 } else {
98 new->namelen = 0;
99 new->addrlen = 0;
100 }
101}
102
103static void nfs_dns_ent_put(struct kref *ref)
104{
105 struct nfs_dns_ent *item;
106
107 item = container_of(ref, struct nfs_dns_ent, h.ref);
108 kfree(item->hostname);
109 kfree(item);
110}
111
112static struct cache_head *nfs_dns_ent_alloc(void)
113{
114 struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL);
115
116 if (item != NULL) {
117 item->hostname = NULL;
118 item->namelen = 0;
119 item->addrlen = 0;
120 return &item->h;
121 }
122 return NULL;
123};
124
125static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
126{
127 return hash_str(key->hostname, NFS_DNS_HASHBITS);
128}
129
130static void nfs_dns_request(struct cache_detail *cd,
131 struct cache_head *ch,
132 char **bpp, int *blen)
133{
134 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
135
136 qword_add(bpp, blen, key->hostname);
137 (*bpp)[-1] = '\n';
138}
139
140static int nfs_dns_upcall(struct cache_detail *cd,
141 struct cache_head *ch)
142{
143 struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h);
144 int ret;
145
146 ret = nfs_cache_upcall(cd, key->hostname);
147 if (ret)
148 ret = sunrpc_cache_pipe_upcall(cd, ch);
149 return ret;
150}
151
152static int nfs_dns_match(struct cache_head *ca,
153 struct cache_head *cb)
154{
155 struct nfs_dns_ent *a;
156 struct nfs_dns_ent *b;
157
158 a = container_of(ca, struct nfs_dns_ent, h);
159 b = container_of(cb, struct nfs_dns_ent, h);
160
161 if (a->namelen == 0 || a->namelen != b->namelen)
162 return 0;
163 return memcmp(a->hostname, b->hostname, a->namelen) == 0;
164}
165
166static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd,
167 struct cache_head *h)
168{
169 struct nfs_dns_ent *item;
170 long ttl;
171
172 if (h == NULL) {
173 seq_puts(m, "# ip address hostname ttl\n");
174 return 0;
175 }
176 item = container_of(h, struct nfs_dns_ent, h);
177 ttl = item->h.expiry_time - seconds_since_boot();
178 if (ttl < 0)
179 ttl = 0;
180
181 if (!test_bit(CACHE_NEGATIVE, &h->flags)) {
182 char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1];
183
184 rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf));
185 seq_printf(m, "%15s ", buf);
186 } else
187 seq_puts(m, "<none> ");
188 seq_printf(m, "%15s %ld\n", item->hostname, ttl);
189 return 0;
190}
191
192static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd,
193 struct nfs_dns_ent *key)
194{
195 struct cache_head *ch;
196
197 ch = sunrpc_cache_lookup(cd,
198 &key->h,
199 nfs_dns_hash(key));
200 if (!ch)
201 return NULL;
202 return container_of(ch, struct nfs_dns_ent, h);
203}
204
205static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd,
206 struct nfs_dns_ent *new,
207 struct nfs_dns_ent *key)
208{
209 struct cache_head *ch;
210
211 ch = sunrpc_cache_update(cd,
212 &new->h, &key->h,
213 nfs_dns_hash(key));
214 if (!ch)
215 return NULL;
216 return container_of(ch, struct nfs_dns_ent, h);
217}
218
219static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen)
220{
221 char buf1[NFS_DNS_HOSTNAME_MAXLEN+1];
222 struct nfs_dns_ent key, *item;
223 unsigned int ttl;
224 ssize_t len;
225 int ret = -EINVAL;
226
227 if (buf[buflen-1] != '\n')
228 goto out;
229 buf[buflen-1] = '\0';
230
231 len = qword_get(&buf, buf1, sizeof(buf1));
232 if (len <= 0)
233 goto out;
234 key.addrlen = rpc_pton(cd->net, buf1, len,
235 (struct sockaddr *)&key.addr,
236 sizeof(key.addr));
237
238 len = qword_get(&buf, buf1, sizeof(buf1));
239 if (len <= 0)
240 goto out;
241
242 key.hostname = buf1;
243 key.namelen = len;
244 memset(&key.h, 0, sizeof(key.h));
245
246 if (get_uint(&buf, &ttl) < 0)
247 goto out;
248 if (ttl == 0)
249 goto out;
250 key.h.expiry_time = ttl + seconds_since_boot();
251
252 ret = -ENOMEM;
253 item = nfs_dns_lookup(cd, &key);
254 if (item == NULL)
255 goto out;
256
257 if (key.addrlen == 0)
258 set_bit(CACHE_NEGATIVE, &key.h.flags);
259
260 item = nfs_dns_update(cd, &key, item);
261 if (item == NULL)
262 goto out;
263
264 ret = 0;
265 cache_put(&item->h, cd);
266out:
267 return ret;
268}
269
270static int do_cache_lookup(struct cache_detail *cd,
271 struct nfs_dns_ent *key,
272 struct nfs_dns_ent **item,
273 struct nfs_cache_defer_req *dreq)
274{
275 int ret = -ENOMEM;
276
277 *item = nfs_dns_lookup(cd, key);
278 if (*item) {
279 ret = cache_check(cd, &(*item)->h, &dreq->req);
280 if (ret)
281 *item = NULL;
282 }
283 return ret;
284}
285
286static int do_cache_lookup_nowait(struct cache_detail *cd,
287 struct nfs_dns_ent *key,
288 struct nfs_dns_ent **item)
289{
290 int ret = -ENOMEM;
291
292 *item = nfs_dns_lookup(cd, key);
293 if (!*item)
294 goto out_err;
295 ret = -ETIMEDOUT;
296 if (!test_bit(CACHE_VALID, &(*item)->h.flags)
297 || (*item)->h.expiry_time < seconds_since_boot()
298 || cd->flush_time > (*item)->h.last_refresh)
299 goto out_put;
300 ret = -ENOENT;
301 if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
302 goto out_put;
303 return 0;
304out_put:
305 cache_put(&(*item)->h, cd);
306out_err:
307 *item = NULL;
308 return ret;
309}
310
311static int do_cache_lookup_wait(struct cache_detail *cd,
312 struct nfs_dns_ent *key,
313 struct nfs_dns_ent **item)
314{
315 struct nfs_cache_defer_req *dreq;
316 int ret = -ENOMEM;
317
318 dreq = nfs_cache_defer_req_alloc();
319 if (!dreq)
320 goto out;
321 ret = do_cache_lookup(cd, key, item, dreq);
322 if (ret == -EAGAIN) {
323 ret = nfs_cache_wait_for_upcall(dreq);
324 if (!ret)
325 ret = do_cache_lookup_nowait(cd, key, item);
326 }
327 nfs_cache_defer_req_put(dreq);
328out:
329 return ret;
330}
331
332ssize_t nfs_dns_resolve_name(struct net *net, char *name,
333 size_t namelen, struct sockaddr *sa, size_t salen)
334{
335 struct nfs_dns_ent key = {
336 .hostname = name,
337 .namelen = namelen,
338 };
339 struct nfs_dns_ent *item = NULL;
340 ssize_t ret;
341 struct nfs_net *nn = net_generic(net, nfs_net_id);
342
343 ret = do_cache_lookup_wait(nn->nfs_dns_resolve, &key, &item);
344 if (ret == 0) {
345 if (salen >= item->addrlen) {
346 memcpy(sa, &item->addr, item->addrlen);
347 ret = item->addrlen;
348 } else
349 ret = -EOVERFLOW;
350 cache_put(&item->h, nn->nfs_dns_resolve);
351 } else if (ret == -ENOENT)
352 ret = -ESRCH;
353 return ret;
354}
355
356static 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,
362 .cache_request = nfs_dns_request,
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
372int nfs_dns_resolver_cache_init(struct net *net)
373{
374 int err;
375 struct nfs_net *nn = net_generic(net, nfs_net_id);
376
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
381 err = nfs_cache_register_net(net, nn->nfs_dns_resolve);
382 if (err)
383 goto err_reg;
384 return 0;
385
386err_reg:
387 cache_destroy_net(nn->nfs_dns_resolve, net);
388 return err;
389}
390
391void nfs_dns_resolver_cache_destroy(struct net *net)
392{
393 struct nfs_net *nn = net_generic(net, nfs_net_id);
394
395 nfs_cache_unregister_net(net, nn->nfs_dns_resolve);
396 cache_destroy_net(nn->nfs_dns_resolve, net);
397}
398
399static int nfs4_dns_net_init(struct net *net)
400{
401 return nfs_dns_resolver_cache_init(net);
402}
403
404static void nfs4_dns_net_exit(struct net *net)
405{
406 nfs_dns_resolver_cache_destroy(net);
407}
408
409static struct pernet_operations nfs4_dns_resolver_ops = {
410 .init = nfs4_dns_net_init,
411 .exit = nfs4_dns_net_exit,
412};
413
414static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
415 void *ptr)
416{
417 struct super_block *sb = ptr;
418 struct net *net = sb->s_fs_info;
419 struct nfs_net *nn = net_generic(net, nfs_net_id);
420 struct cache_detail *cd = nn->nfs_dns_resolve;
421 int ret = 0;
422
423 if (cd == NULL)
424 return 0;
425
426 if (!try_module_get(THIS_MODULE))
427 return 0;
428
429 switch (event) {
430 case RPC_PIPEFS_MOUNT:
431 ret = nfs_cache_register_sb(sb, cd);
432 break;
433 case RPC_PIPEFS_UMOUNT:
434 nfs_cache_unregister_sb(sb, cd);
435 break;
436 default:
437 ret = -ENOTSUPP;
438 break;
439 }
440 module_put(THIS_MODULE);
441 return ret;
442}
443
444static struct notifier_block nfs_dns_resolver_block = {
445 .notifier_call = rpc_pipefs_event,
446};
447
448int nfs_dns_resolver_init(void)
449{
450 int err;
451
452 err = register_pernet_subsys(&nfs4_dns_resolver_ops);
453 if (err < 0)
454 goto out;
455 err = rpc_pipefs_notifier_register(&nfs_dns_resolver_block);
456 if (err < 0)
457 goto out1;
458 return 0;
459out1:
460 unregister_pernet_subsys(&nfs4_dns_resolver_ops);
461out:
462 return err;
463}
464
465void nfs_dns_resolver_destroy(void)
466{
467 rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block);
468 unregister_pernet_subsys(&nfs4_dns_resolver_ops);
469}
470#endif
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
9#ifdef CONFIG_NFS_USE_KERNEL_DNS
10
11#include <linux/sunrpc/clnt.h>
12#include <linux/dns_resolver.h>
13
14ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
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)
23 ret = rpc_pton(ip_addr, ip_len, sa, salen);
24 else
25 ret = -ESRCH;
26 kfree(ip_addr);
27 return ret;
28}
29
30#else
31
32#include <linux/hash.h>
33#include <linux/string.h>
34#include <linux/kmod.h>
35#include <linux/slab.h>
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>
43
44#include "dns_resolve.h"
45#include "cache_lib.h"
46
47#define NFS_DNS_HASHBITS 4
48#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS)
49
50static struct cache_head *nfs_dns_table[NFS_DNS_HASHTBL_SIZE];
51
52struct 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
63static 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
76static 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;
89 nfs_dns_ent_update(cnew, ckey);
90 } else {
91 new->namelen = 0;
92 new->addrlen = 0;
93 }
94}
95
96static 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
105static 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
118static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key)
119{
120 return hash_str(key->hostname, NFS_DNS_HASHBITS);
121}
122
123static 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
133static 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
145static 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
159static 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);
170 ttl = item->h.expiry_time - seconds_since_boot();
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
185static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd,
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
198static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd,
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
212static 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;
227 key.addrlen = rpc_pton(buf1, len,
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;
242 key.h.expiry_time = ttl + seconds_since_boot();
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);
258out:
259 return ret;
260}
261
262static struct cache_detail nfs_dns_resolve = {
263 .owner = THIS_MODULE,
264 .hash_size = NFS_DNS_HASHTBL_SIZE,
265 .hash_table = nfs_dns_table,
266 .name = "dns_resolve",
267 .cache_put = nfs_dns_ent_put,
268 .cache_upcall = nfs_dns_upcall,
269 .cache_parse = nfs_dns_parse,
270 .cache_show = nfs_dns_show,
271 .match = nfs_dns_match,
272 .init = nfs_dns_ent_init,
273 .update = nfs_dns_ent_update,
274 .alloc = nfs_dns_ent_alloc,
275};
276
277static int do_cache_lookup(struct cache_detail *cd,
278 struct nfs_dns_ent *key,
279 struct nfs_dns_ent **item,
280 struct nfs_cache_defer_req *dreq)
281{
282 int ret = -ENOMEM;
283
284 *item = nfs_dns_lookup(cd, key);
285 if (*item) {
286 ret = cache_check(cd, &(*item)->h, &dreq->req);
287 if (ret)
288 *item = NULL;
289 }
290 return ret;
291}
292
293static int do_cache_lookup_nowait(struct cache_detail *cd,
294 struct nfs_dns_ent *key,
295 struct nfs_dns_ent **item)
296{
297 int ret = -ENOMEM;
298
299 *item = nfs_dns_lookup(cd, key);
300 if (!*item)
301 goto out_err;
302 ret = -ETIMEDOUT;
303 if (!test_bit(CACHE_VALID, &(*item)->h.flags)
304 || (*item)->h.expiry_time < seconds_since_boot()
305 || cd->flush_time > (*item)->h.last_refresh)
306 goto out_put;
307 ret = -ENOENT;
308 if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags))
309 goto out_put;
310 return 0;
311out_put:
312 cache_put(&(*item)->h, cd);
313out_err:
314 *item = NULL;
315 return ret;
316}
317
318static int do_cache_lookup_wait(struct cache_detail *cd,
319 struct nfs_dns_ent *key,
320 struct nfs_dns_ent **item)
321{
322 struct nfs_cache_defer_req *dreq;
323 int ret = -ENOMEM;
324
325 dreq = nfs_cache_defer_req_alloc();
326 if (!dreq)
327 goto out;
328 ret = do_cache_lookup(cd, key, item, dreq);
329 if (ret == -EAGAIN) {
330 ret = nfs_cache_wait_for_upcall(dreq);
331 if (!ret)
332 ret = do_cache_lookup_nowait(cd, key, item);
333 }
334 nfs_cache_defer_req_put(dreq);
335out:
336 return ret;
337}
338
339ssize_t nfs_dns_resolve_name(char *name, size_t namelen,
340 struct sockaddr *sa, size_t salen)
341{
342 struct nfs_dns_ent key = {
343 .hostname = name,
344 .namelen = namelen,
345 };
346 struct nfs_dns_ent *item = NULL;
347 ssize_t ret;
348
349 ret = do_cache_lookup_wait(&nfs_dns_resolve, &key, &item);
350 if (ret == 0) {
351 if (salen >= item->addrlen) {
352 memcpy(sa, &item->addr, item->addrlen);
353 ret = item->addrlen;
354 } else
355 ret = -EOVERFLOW;
356 cache_put(&item->h, &nfs_dns_resolve);
357 } else if (ret == -ENOENT)
358 ret = -ESRCH;
359 return ret;
360}
361
362int nfs_dns_resolver_init(void)
363{
364 return nfs_cache_register(&nfs_dns_resolve);
365}
366
367void nfs_dns_resolver_destroy(void)
368{
369 nfs_cache_unregister(&nfs_dns_resolve);
370}
371
372#endif