012e49aaecd130ddb7b10f384523290af0bf6a24
[linux-2.6.git] / fs / lockd / host.c
1 /*
2  * linux/fs/lockd/host.c
3  *
4  * Management for NLM peer hosts. The nlm_host struct is shared
5  * between client and server implementation. The only reason to
6  * do so is to reduce code bloat.
7  *
8  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
9  */
10
11 #include <linux/types.h>
12 #include <linux/slab.h>
13 #include <linux/in.h>
14 #include <linux/in6.h>
15 #include <linux/sunrpc/clnt.h>
16 #include <linux/sunrpc/svc.h>
17 #include <linux/lockd/lockd.h>
18 #include <linux/lockd/sm_inter.h>
19 #include <linux/mutex.h>
20
21 #include <net/ipv6.h>
22
23 #define NLMDBG_FACILITY         NLMDBG_HOSTCACHE
24 #define NLM_HOST_NRHASH         32
25 #define NLM_HOST_REBIND         (60 * HZ)
26 #define NLM_HOST_EXPIRE         (300 * HZ)
27 #define NLM_HOST_COLLECT        (120 * HZ)
28
29 static struct hlist_head        nlm_hosts[NLM_HOST_NRHASH];
30 static unsigned long            next_gc;
31 static int                      nrhosts;
32 static DEFINE_MUTEX(nlm_host_mutex);
33
34 static void                     nlm_gc_hosts(void);
35 static struct nsm_handle        *nsm_find(const struct sockaddr *sap,
36                                                 const size_t salen,
37                                                 const char *hostname,
38                                                 const size_t hostname_len,
39                                                 const int create);
40
41 struct nlm_lookup_host_info {
42         const int               server;         /* search for server|client */
43         const struct sockaddr   *sap;           /* address to search for */
44         const size_t            salen;          /* it's length */
45         const unsigned short    protocol;       /* transport to search for*/
46         const u32               version;        /* NLM version to search for */
47         const char              *hostname;      /* remote's hostname */
48         const size_t            hostname_len;   /* it's length */
49         const struct sockaddr   *src_sap;       /* our address (optional) */
50         const size_t            src_len;        /* it's length */
51         const int               noresvport;     /* use non-priv port */
52 };
53
54 /*
55  * Hash function must work well on big- and little-endian platforms
56  */
57 static unsigned int __nlm_hash32(const __be32 n)
58 {
59         unsigned int hash = (__force u32)n ^ ((__force u32)n >> 16);
60         return hash ^ (hash >> 8);
61 }
62
63 static unsigned int __nlm_hash_addr4(const struct sockaddr *sap)
64 {
65         const struct sockaddr_in *sin = (struct sockaddr_in *)sap;
66         return __nlm_hash32(sin->sin_addr.s_addr);
67 }
68
69 static unsigned int __nlm_hash_addr6(const struct sockaddr *sap)
70 {
71         const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
72         const struct in6_addr addr = sin6->sin6_addr;
73         return __nlm_hash32(addr.s6_addr32[0]) ^
74                __nlm_hash32(addr.s6_addr32[1]) ^
75                __nlm_hash32(addr.s6_addr32[2]) ^
76                __nlm_hash32(addr.s6_addr32[3]);
77 }
78
79 static unsigned int nlm_hash_address(const struct sockaddr *sap)
80 {
81         unsigned int hash;
82
83         switch (sap->sa_family) {
84         case AF_INET:
85                 hash = __nlm_hash_addr4(sap);
86                 break;
87         case AF_INET6:
88                 hash = __nlm_hash_addr6(sap);
89                 break;
90         default:
91                 hash = 0;
92         }
93         return hash & (NLM_HOST_NRHASH - 1);
94 }
95
96 static void nlm_clear_port(struct sockaddr *sap)
97 {
98         switch (sap->sa_family) {
99         case AF_INET:
100                 ((struct sockaddr_in *)sap)->sin_port = 0;
101                 break;
102         case AF_INET6:
103                 ((struct sockaddr_in6 *)sap)->sin6_port = 0;
104                 break;
105         }
106 }
107
108 static void nlm_display_ipv6_address(const struct sockaddr *sap, char *buf,
109                                      const size_t len)
110 {
111         const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
112
113         if (ipv6_addr_v4mapped(&sin6->sin6_addr))
114                 snprintf(buf, len, "%pI4", &sin6->sin6_addr.s6_addr32[3]);
115         else if (sin6->sin6_scope_id != 0)
116                 snprintf(buf, len, "%pI6%%%u", &sin6->sin6_addr,
117                                 sin6->sin6_scope_id);
118         else
119                 snprintf(buf, len, "%pI6", &sin6->sin6_addr);
120 }
121
122 static void nlm_display_address(const struct sockaddr *sap,
123                                 char *buf, const size_t len)
124 {
125         const struct sockaddr_in *sin = (struct sockaddr_in *)sap;
126
127         switch (sap->sa_family) {
128         case AF_INET:
129                 snprintf(buf, len, "%pI4", &sin->sin_addr.s_addr);
130                 break;
131         case AF_INET6:
132                 nlm_display_ipv6_address(sap, buf, len);
133                 break;
134         default:
135                 snprintf(buf, len, "unsupported address family");
136                 break;
137         }
138 }
139
140 /*
141  * Common host lookup routine for server & client
142  */
143 static struct nlm_host *nlm_lookup_host(struct nlm_lookup_host_info *ni)
144 {
145         struct hlist_head *chain;
146         struct hlist_node *pos;
147         struct nlm_host *host;
148         struct nsm_handle *nsm = NULL;
149
150         mutex_lock(&nlm_host_mutex);
151
152         if (time_after_eq(jiffies, next_gc))
153                 nlm_gc_hosts();
154
155         /* We may keep several nlm_host objects for a peer, because each
156          * nlm_host is identified by
157          * (address, protocol, version, server/client)
158          * We could probably simplify this a little by putting all those
159          * different NLM rpc_clients into one single nlm_host object.
160          * This would allow us to have one nlm_host per address.
161          */
162         chain = &nlm_hosts[nlm_hash_address(ni->sap)];
163         hlist_for_each_entry(host, pos, chain, h_hash) {
164                 if (!nlm_cmp_addr(nlm_addr(host), ni->sap))
165                         continue;
166
167                 /* See if we have an NSM handle for this client */
168                 if (!nsm)
169                         nsm = host->h_nsmhandle;
170
171                 if (host->h_proto != ni->protocol)
172                         continue;
173                 if (host->h_version != ni->version)
174                         continue;
175                 if (host->h_server != ni->server)
176                         continue;
177                 if (ni->server &&
178                     !nlm_cmp_addr(nlm_srcaddr(host), ni->src_sap))
179                         continue;
180
181                 /* Move to head of hash chain. */
182                 hlist_del(&host->h_hash);
183                 hlist_add_head(&host->h_hash, chain);
184
185                 nlm_get_host(host);
186                 dprintk("lockd: nlm_lookup_host found host %s (%s)\n",
187                                 host->h_name, host->h_addrbuf);
188                 goto out;
189         }
190
191         /*
192          * The host wasn't in our hash table.  If we don't
193          * have an NSM handle for it yet, create one.
194          */
195         if (nsm)
196                 atomic_inc(&nsm->sm_count);
197         else {
198                 host = NULL;
199                 nsm = nsm_find(ni->sap, ni->salen,
200                                 ni->hostname, ni->hostname_len, 1);
201                 if (!nsm) {
202                         dprintk("lockd: nlm_lookup_host failed; "
203                                 "no nsm handle\n");
204                         goto out;
205                 }
206         }
207
208         host = kzalloc(sizeof(*host), GFP_KERNEL);
209         if (!host) {
210                 nsm_release(nsm);
211                 dprintk("lockd: nlm_lookup_host failed; no memory\n");
212                 goto out;
213         }
214         host->h_name       = nsm->sm_name;
215         host->h_addrbuf    = nsm->sm_addrbuf;
216         memcpy(nlm_addr(host), ni->sap, ni->salen);
217         host->h_addrlen = ni->salen;
218         nlm_clear_port(nlm_addr(host));
219         memcpy(nlm_srcaddr(host), ni->src_sap, ni->src_len);
220         host->h_version    = ni->version;
221         host->h_proto      = ni->protocol;
222         host->h_rpcclnt    = NULL;
223         mutex_init(&host->h_mutex);
224         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
225         host->h_expires    = jiffies + NLM_HOST_EXPIRE;
226         atomic_set(&host->h_count, 1);
227         init_waitqueue_head(&host->h_gracewait);
228         init_rwsem(&host->h_rwsem);
229         host->h_state      = 0;                 /* pseudo NSM state */
230         host->h_nsmstate   = 0;                 /* real NSM state */
231         host->h_nsmhandle  = nsm;
232         host->h_server     = ni->server;
233         host->h_noresvport = ni->noresvport;
234         hlist_add_head(&host->h_hash, chain);
235         INIT_LIST_HEAD(&host->h_lockowners);
236         spin_lock_init(&host->h_lock);
237         INIT_LIST_HEAD(&host->h_granted);
238         INIT_LIST_HEAD(&host->h_reclaim);
239
240         nrhosts++;
241
242         dprintk("lockd: nlm_lookup_host created host %s\n",
243                         host->h_name);
244
245 out:
246         mutex_unlock(&nlm_host_mutex);
247         return host;
248 }
249
250 /*
251  * Destroy a host
252  */
253 static void
254 nlm_destroy_host(struct nlm_host *host)
255 {
256         struct rpc_clnt *clnt;
257
258         BUG_ON(!list_empty(&host->h_lockowners));
259         BUG_ON(atomic_read(&host->h_count));
260
261         /*
262          * Release NSM handle and unmonitor host.
263          */
264         nsm_unmonitor(host);
265
266         clnt = host->h_rpcclnt;
267         if (clnt != NULL)
268                 rpc_shutdown_client(clnt);
269         kfree(host);
270 }
271
272 /**
273  * nlmclnt_lookup_host - Find an NLM host handle matching a remote server
274  * @sap: network address of server
275  * @salen: length of server address
276  * @protocol: transport protocol to use
277  * @version: NLM protocol version
278  * @hostname: '\0'-terminated hostname of server
279  * @noresvport: 1 if non-privileged port should be used
280  *
281  * Returns an nlm_host structure that matches the passed-in
282  * [server address, transport protocol, NLM version, server hostname].
283  * If one doesn't already exist in the host cache, a new handle is
284  * created and returned.
285  */
286 struct nlm_host *nlmclnt_lookup_host(const struct sockaddr *sap,
287                                      const size_t salen,
288                                      const unsigned short protocol,
289                                      const u32 version,
290                                      const char *hostname,
291                                      int noresvport)
292 {
293         const struct sockaddr source = {
294                 .sa_family      = AF_UNSPEC,
295         };
296         struct nlm_lookup_host_info ni = {
297                 .server         = 0,
298                 .sap            = sap,
299                 .salen          = salen,
300                 .protocol       = protocol,
301                 .version        = version,
302                 .hostname       = hostname,
303                 .hostname_len   = strlen(hostname),
304                 .src_sap        = &source,
305                 .src_len        = sizeof(source),
306                 .noresvport     = noresvport,
307         };
308
309         dprintk("lockd: %s(host='%s', vers=%u, proto=%s)\n", __func__,
310                         (hostname ? hostname : "<none>"), version,
311                         (protocol == IPPROTO_UDP ? "udp" : "tcp"));
312
313         return nlm_lookup_host(&ni);
314 }
315
316 /**
317  * nlmsvc_lookup_host - Find an NLM host handle matching a remote client
318  * @rqstp: incoming NLM request
319  * @hostname: name of client host
320  * @hostname_len: length of client hostname
321  *
322  * Returns an nlm_host structure that matches the [client address,
323  * transport protocol, NLM version, client hostname] of the passed-in
324  * NLM request.  If one doesn't already exist in the host cache, a
325  * new handle is created and returned.
326  *
327  * Before possibly creating a new nlm_host, construct a sockaddr
328  * for a specific source address in case the local system has
329  * multiple network addresses.  The family of the address in
330  * rq_daddr is guaranteed to be the same as the family of the
331  * address in rq_addr, so it's safe to use the same family for
332  * the source address.
333  */
334 struct nlm_host *nlmsvc_lookup_host(const struct svc_rqst *rqstp,
335                                     const char *hostname,
336                                     const size_t hostname_len)
337 {
338         struct sockaddr_in sin = {
339                 .sin_family     = AF_INET,
340         };
341         struct sockaddr_in6 sin6 = {
342                 .sin6_family    = AF_INET6,
343         };
344         struct nlm_lookup_host_info ni = {
345                 .server         = 1,
346                 .sap            = svc_addr(rqstp),
347                 .salen          = rqstp->rq_addrlen,
348                 .protocol       = rqstp->rq_prot,
349                 .version        = rqstp->rq_vers,
350                 .hostname       = hostname,
351                 .hostname_len   = hostname_len,
352                 .src_len        = rqstp->rq_addrlen,
353         };
354
355         dprintk("lockd: %s(host='%*s', vers=%u, proto=%s)\n", __func__,
356                         (int)hostname_len, hostname, rqstp->rq_vers,
357                         (rqstp->rq_prot == IPPROTO_UDP ? "udp" : "tcp"));
358
359         switch (ni.sap->sa_family) {
360         case AF_INET:
361                 sin.sin_addr.s_addr = rqstp->rq_daddr.addr.s_addr;
362                 ni.src_sap = (struct sockaddr *)&sin;
363                 break;
364         case AF_INET6:
365                 ipv6_addr_copy(&sin6.sin6_addr, &rqstp->rq_daddr.addr6);
366                 ni.src_sap = (struct sockaddr *)&sin6;
367                 break;
368         default:
369                 return NULL;
370         }
371
372         return nlm_lookup_host(&ni);
373 }
374
375 /*
376  * Create the NLM RPC client for an NLM peer
377  */
378 struct rpc_clnt *
379 nlm_bind_host(struct nlm_host *host)
380 {
381         struct rpc_clnt *clnt;
382
383         dprintk("lockd: nlm_bind_host %s (%s)\n",
384                         host->h_name, host->h_addrbuf);
385
386         /* Lock host handle */
387         mutex_lock(&host->h_mutex);
388
389         /* If we've already created an RPC client, check whether
390          * RPC rebind is required
391          */
392         if ((clnt = host->h_rpcclnt) != NULL) {
393                 if (time_after_eq(jiffies, host->h_nextrebind)) {
394                         rpc_force_rebind(clnt);
395                         host->h_nextrebind = jiffies + NLM_HOST_REBIND;
396                         dprintk("lockd: next rebind in %lu jiffies\n",
397                                         host->h_nextrebind - jiffies);
398                 }
399         } else {
400                 unsigned long increment = nlmsvc_timeout;
401                 struct rpc_timeout timeparms = {
402                         .to_initval     = increment,
403                         .to_increment   = increment,
404                         .to_maxval      = increment * 6UL,
405                         .to_retries     = 5U,
406                 };
407                 struct rpc_create_args args = {
408                         .protocol       = host->h_proto,
409                         .address        = nlm_addr(host),
410                         .addrsize       = host->h_addrlen,
411                         .saddress       = nlm_srcaddr(host),
412                         .timeout        = &timeparms,
413                         .servername     = host->h_name,
414                         .program        = &nlm_program,
415                         .version        = host->h_version,
416                         .authflavor     = RPC_AUTH_UNIX,
417                         .flags          = (RPC_CLNT_CREATE_NOPING |
418                                            RPC_CLNT_CREATE_AUTOBIND),
419                 };
420
421                 /*
422                  * lockd retries server side blocks automatically so we want
423                  * those to be soft RPC calls. Client side calls need to be
424                  * hard RPC tasks.
425                  */
426                 if (!host->h_server)
427                         args.flags |= RPC_CLNT_CREATE_HARDRTRY;
428                 if (host->h_noresvport)
429                         args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;
430
431                 clnt = rpc_create(&args);
432                 if (!IS_ERR(clnt))
433                         host->h_rpcclnt = clnt;
434                 else {
435                         printk("lockd: couldn't create RPC handle for %s\n", host->h_name);
436                         clnt = NULL;
437                 }
438         }
439
440         mutex_unlock(&host->h_mutex);
441         return clnt;
442 }
443
444 /*
445  * Force a portmap lookup of the remote lockd port
446  */
447 void
448 nlm_rebind_host(struct nlm_host *host)
449 {
450         dprintk("lockd: rebind host %s\n", host->h_name);
451         if (host->h_rpcclnt && time_after_eq(jiffies, host->h_nextrebind)) {
452                 rpc_force_rebind(host->h_rpcclnt);
453                 host->h_nextrebind = jiffies + NLM_HOST_REBIND;
454         }
455 }
456
457 /*
458  * Increment NLM host count
459  */
460 struct nlm_host * nlm_get_host(struct nlm_host *host)
461 {
462         if (host) {
463                 dprintk("lockd: get host %s\n", host->h_name);
464                 atomic_inc(&host->h_count);
465                 host->h_expires = jiffies + NLM_HOST_EXPIRE;
466         }
467         return host;
468 }
469
470 /*
471  * Release NLM host after use
472  */
473 void nlm_release_host(struct nlm_host *host)
474 {
475         if (host != NULL) {
476                 dprintk("lockd: release host %s\n", host->h_name);
477                 BUG_ON(atomic_read(&host->h_count) < 0);
478                 if (atomic_dec_and_test(&host->h_count)) {
479                         BUG_ON(!list_empty(&host->h_lockowners));
480                         BUG_ON(!list_empty(&host->h_granted));
481                         BUG_ON(!list_empty(&host->h_reclaim));
482                 }
483         }
484 }
485
486 /*
487  * We were notified that the host indicated by address &sin
488  * has rebooted.
489  * Release all resources held by that peer.
490  */
491 void nlm_host_rebooted(const struct sockaddr_in *sin,
492                                 const char *hostname,
493                                 unsigned int hostname_len,
494                                 u32 new_state)
495 {
496         struct hlist_head *chain;
497         struct hlist_node *pos;
498         struct nsm_handle *nsm;
499         struct nlm_host *host;
500
501         nsm = nsm_find((struct sockaddr *)sin, sizeof(*sin),
502                         hostname, hostname_len, 0);
503         if (nsm == NULL) {
504                 dprintk("lockd: never saw rebooted peer '%.*s' before\n",
505                                 hostname_len, hostname);
506                 return;
507         }
508
509         dprintk("lockd: nlm_host_rebooted(%.*s, %s)\n",
510                         hostname_len, hostname, nsm->sm_addrbuf);
511
512         /* When reclaiming locks on this peer, make sure that
513          * we set up a new notification */
514         nsm->sm_monitored = 0;
515
516         /* Mark all hosts tied to this NSM state as having rebooted.
517          * We run the loop repeatedly, because we drop the host table
518          * lock for this.
519          * To avoid processing a host several times, we match the nsmstate.
520          */
521 again:  mutex_lock(&nlm_host_mutex);
522         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
523                 hlist_for_each_entry(host, pos, chain, h_hash) {
524                         if (host->h_nsmhandle == nsm
525                          && host->h_nsmstate != new_state) {
526                                 host->h_nsmstate = new_state;
527                                 host->h_state++;
528
529                                 nlm_get_host(host);
530                                 mutex_unlock(&nlm_host_mutex);
531
532                                 if (host->h_server) {
533                                         /* We're server for this guy, just ditch
534                                          * all the locks he held. */
535                                         nlmsvc_free_host_resources(host);
536                                 } else {
537                                         /* He's the server, initiate lock recovery. */
538                                         nlmclnt_recovery(host);
539                                 }
540
541                                 nlm_release_host(host);
542                                 goto again;
543                         }
544                 }
545         }
546
547         mutex_unlock(&nlm_host_mutex);
548 }
549
550 /*
551  * Shut down the hosts module.
552  * Note that this routine is called only at server shutdown time.
553  */
554 void
555 nlm_shutdown_hosts(void)
556 {
557         struct hlist_head *chain;
558         struct hlist_node *pos;
559         struct nlm_host *host;
560
561         dprintk("lockd: shutting down host module\n");
562         mutex_lock(&nlm_host_mutex);
563
564         /* First, make all hosts eligible for gc */
565         dprintk("lockd: nuking all hosts...\n");
566         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
567                 hlist_for_each_entry(host, pos, chain, h_hash) {
568                         host->h_expires = jiffies - 1;
569                         if (host->h_rpcclnt) {
570                                 rpc_shutdown_client(host->h_rpcclnt);
571                                 host->h_rpcclnt = NULL;
572                         }
573                 }
574         }
575
576         /* Then, perform a garbage collection pass */
577         nlm_gc_hosts();
578         mutex_unlock(&nlm_host_mutex);
579
580         /* complain if any hosts are left */
581         if (nrhosts) {
582                 printk(KERN_WARNING "lockd: couldn't shutdown host module!\n");
583                 dprintk("lockd: %d hosts left:\n", nrhosts);
584                 for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
585                         hlist_for_each_entry(host, pos, chain, h_hash) {
586                                 dprintk("       %s (cnt %d use %d exp %ld)\n",
587                                         host->h_name, atomic_read(&host->h_count),
588                                         host->h_inuse, host->h_expires);
589                         }
590                 }
591         }
592 }
593
594 /*
595  * Garbage collect any unused NLM hosts.
596  * This GC combines reference counting for async operations with
597  * mark & sweep for resources held by remote clients.
598  */
599 static void
600 nlm_gc_hosts(void)
601 {
602         struct hlist_head *chain;
603         struct hlist_node *pos, *next;
604         struct nlm_host *host;
605
606         dprintk("lockd: host garbage collection\n");
607         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
608                 hlist_for_each_entry(host, pos, chain, h_hash)
609                         host->h_inuse = 0;
610         }
611
612         /* Mark all hosts that hold locks, blocks or shares */
613         nlmsvc_mark_resources();
614
615         for (chain = nlm_hosts; chain < nlm_hosts + NLM_HOST_NRHASH; ++chain) {
616                 hlist_for_each_entry_safe(host, pos, next, chain, h_hash) {
617                         if (atomic_read(&host->h_count) || host->h_inuse
618                          || time_before(jiffies, host->h_expires)) {
619                                 dprintk("nlm_gc_hosts skipping %s (cnt %d use %d exp %ld)\n",
620                                         host->h_name, atomic_read(&host->h_count),
621                                         host->h_inuse, host->h_expires);
622                                 continue;
623                         }
624                         dprintk("lockd: delete host %s\n", host->h_name);
625                         hlist_del_init(&host->h_hash);
626
627                         nlm_destroy_host(host);
628                         nrhosts--;
629                 }
630         }
631
632         next_gc = jiffies + NLM_HOST_COLLECT;
633 }
634
635
636 /*
637  * Manage NSM handles
638  */
639 static LIST_HEAD(nsm_handles);
640 static DEFINE_SPINLOCK(nsm_lock);
641
642 static struct nsm_handle *nsm_find(const struct sockaddr *sap,
643                                    const size_t salen,
644                                    const char *hostname,
645                                    const size_t hostname_len,
646                                    const int create)
647 {
648         struct nsm_handle *nsm = NULL;
649         struct nsm_handle *pos;
650
651         if (!sap)
652                 return NULL;
653
654         if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
655                 if (printk_ratelimit()) {
656                         printk(KERN_WARNING "Invalid hostname \"%.*s\" "
657                                             "in NFS lock request\n",
658                                 (int)hostname_len, hostname);
659                 }
660                 return NULL;
661         }
662
663 retry:
664         spin_lock(&nsm_lock);
665         list_for_each_entry(pos, &nsm_handles, sm_link) {
666
667                 if (hostname && nsm_use_hostnames) {
668                         if (strlen(pos->sm_name) != hostname_len
669                          || memcmp(pos->sm_name, hostname, hostname_len))
670                                 continue;
671                 } else if (!nlm_cmp_addr(nsm_addr(pos), sap))
672                         continue;
673                 atomic_inc(&pos->sm_count);
674                 kfree(nsm);
675                 nsm = pos;
676                 goto found;
677         }
678         if (nsm) {
679                 list_add(&nsm->sm_link, &nsm_handles);
680                 goto found;
681         }
682         spin_unlock(&nsm_lock);
683
684         if (!create)
685                 return NULL;
686
687         nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
688         if (nsm == NULL)
689                 return NULL;
690
691         memcpy(nsm_addr(nsm), sap, salen);
692         nsm->sm_addrlen = salen;
693         nsm->sm_name = (char *) (nsm + 1);
694         memcpy(nsm->sm_name, hostname, hostname_len);
695         nsm->sm_name[hostname_len] = '\0';
696         nlm_display_address((struct sockaddr *)&nsm->sm_addr,
697                                 nsm->sm_addrbuf, sizeof(nsm->sm_addrbuf));
698         atomic_set(&nsm->sm_count, 1);
699         goto retry;
700
701 found:
702         spin_unlock(&nsm_lock);
703         return nsm;
704 }
705
706 /*
707  * Release an NSM handle
708  */
709 void
710 nsm_release(struct nsm_handle *nsm)
711 {
712         if (!nsm)
713                 return;
714         if (atomic_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
715                 list_del(&nsm->sm_link);
716                 spin_unlock(&nsm_lock);
717                 kfree(nsm);
718         }
719 }