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TOMOYO Linux Cross Reference
Linux/fs/lockd/host.c

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

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