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Linux/fs/nfsd/nfssvc.c

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  1 /*
  2  * Central processing for nfsd.
  3  *
  4  * Authors:     Olaf Kirch (okir@monad.swb.de)
  5  *
  6  * Copyright (C) 1995, 1996, 1997 Olaf Kirch <okir@monad.swb.de>
  7  */
  8 
  9 #include <linux/sched.h>
 10 #include <linux/freezer.h>
 11 #include <linux/module.h>
 12 #include <linux/fs_struct.h>
 13 #include <linux/swap.h>
 14 
 15 #include <linux/sunrpc/stats.h>
 16 #include <linux/sunrpc/svcsock.h>
 17 #include <linux/sunrpc/svc_xprt.h>
 18 #include <linux/lockd/bind.h>
 19 #include <linux/nfsacl.h>
 20 #include <linux/seq_file.h>
 21 #include <linux/inetdevice.h>
 22 #include <net/addrconf.h>
 23 #include <net/ipv6.h>
 24 #include <net/net_namespace.h>
 25 #include "nfsd.h"
 26 #include "cache.h"
 27 #include "vfs.h"
 28 #include "netns.h"
 29 
 30 #define NFSDDBG_FACILITY        NFSDDBG_SVC
 31 
 32 extern struct svc_program       nfsd_program;
 33 static int                      nfsd(void *vrqstp);
 34 
 35 /*
 36  * nfsd_mutex protects nn->nfsd_serv -- both the pointer itself and the members
 37  * of the svc_serv struct. In particular, ->sv_nrthreads but also to some
 38  * extent ->sv_temp_socks and ->sv_permsocks. It also protects nfsdstats.th_cnt
 39  *
 40  * If (out side the lock) nn->nfsd_serv is non-NULL, then it must point to a
 41  * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0. That number
 42  * of nfsd threads must exist and each must listed in ->sp_all_threads in each
 43  * entry of ->sv_pools[].
 44  *
 45  * Transitions of the thread count between zero and non-zero are of particular
 46  * interest since the svc_serv needs to be created and initialized at that
 47  * point, or freed.
 48  *
 49  * Finally, the nfsd_mutex also protects some of the global variables that are
 50  * accessed when nfsd starts and that are settable via the write_* routines in
 51  * nfsctl.c. In particular:
 52  *
 53  *      user_recovery_dirname
 54  *      user_lease_time
 55  *      nfsd_versions
 56  */
 57 DEFINE_MUTEX(nfsd_mutex);
 58 
 59 /*
 60  * nfsd_drc_lock protects nfsd_drc_max_pages and nfsd_drc_pages_used.
 61  * nfsd_drc_max_pages limits the total amount of memory available for
 62  * version 4.1 DRC caches.
 63  * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage.
 64  */
 65 spinlock_t      nfsd_drc_lock;
 66 unsigned long   nfsd_drc_max_mem;
 67 unsigned long   nfsd_drc_mem_used;
 68 
 69 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
 70 static struct svc_stat  nfsd_acl_svcstats;
 71 static struct svc_version *     nfsd_acl_version[] = {
 72         [2] = &nfsd_acl_version2,
 73         [3] = &nfsd_acl_version3,
 74 };
 75 
 76 #define NFSD_ACL_MINVERS            2
 77 #define NFSD_ACL_NRVERS         ARRAY_SIZE(nfsd_acl_version)
 78 static struct svc_version *nfsd_acl_versions[NFSD_ACL_NRVERS];
 79 
 80 static struct svc_program       nfsd_acl_program = {
 81         .pg_prog                = NFS_ACL_PROGRAM,
 82         .pg_nvers               = NFSD_ACL_NRVERS,
 83         .pg_vers                = nfsd_acl_versions,
 84         .pg_name                = "nfsacl",
 85         .pg_class               = "nfsd",
 86         .pg_stats               = &nfsd_acl_svcstats,
 87         .pg_authenticate        = &svc_set_client,
 88 };
 89 
 90 static struct svc_stat  nfsd_acl_svcstats = {
 91         .program        = &nfsd_acl_program,
 92 };
 93 #endif /* defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL) */
 94 
 95 static struct svc_version *     nfsd_version[] = {
 96         [2] = &nfsd_version2,
 97 #if defined(CONFIG_NFSD_V3)
 98         [3] = &nfsd_version3,
 99 #endif
100 #if defined(CONFIG_NFSD_V4)
101         [4] = &nfsd_version4,
102 #endif
103 };
104 
105 #define NFSD_MINVERS            2
106 #define NFSD_NRVERS             ARRAY_SIZE(nfsd_version)
107 static struct svc_version *nfsd_versions[NFSD_NRVERS];
108 
109 struct svc_program              nfsd_program = {
110 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
111         .pg_next                = &nfsd_acl_program,
112 #endif
113         .pg_prog                = NFS_PROGRAM,          /* program number */
114         .pg_nvers               = NFSD_NRVERS,          /* nr of entries in nfsd_version */
115         .pg_vers                = nfsd_versions,        /* version table */
116         .pg_name                = "nfsd",               /* program name */
117         .pg_class               = "nfsd",               /* authentication class */
118         .pg_stats               = &nfsd_svcstats,       /* version table */
119         .pg_authenticate        = &svc_set_client,      /* export authentication */
120 
121 };
122 
123 static bool nfsd_supported_minorversions[NFSD_SUPPORTED_MINOR_VERSION + 1] = {
124         [0] = 1,
125         [1] = 1,
126         [2] = 1,
127 };
128 
129 int nfsd_vers(int vers, enum vers_op change)
130 {
131         if (vers < NFSD_MINVERS || vers >= NFSD_NRVERS)
132                 return 0;
133         switch(change) {
134         case NFSD_SET:
135                 nfsd_versions[vers] = nfsd_version[vers];
136 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
137                 if (vers < NFSD_ACL_NRVERS)
138                         nfsd_acl_versions[vers] = nfsd_acl_version[vers];
139 #endif
140                 break;
141         case NFSD_CLEAR:
142                 nfsd_versions[vers] = NULL;
143 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
144                 if (vers < NFSD_ACL_NRVERS)
145                         nfsd_acl_versions[vers] = NULL;
146 #endif
147                 break;
148         case NFSD_TEST:
149                 return nfsd_versions[vers] != NULL;
150         case NFSD_AVAIL:
151                 return nfsd_version[vers] != NULL;
152         }
153         return 0;
154 }
155 
156 int nfsd_minorversion(u32 minorversion, enum vers_op change)
157 {
158         if (minorversion > NFSD_SUPPORTED_MINOR_VERSION)
159                 return -1;
160         switch(change) {
161         case NFSD_SET:
162                 nfsd_supported_minorversions[minorversion] = true;
163                 break;
164         case NFSD_CLEAR:
165                 nfsd_supported_minorversions[minorversion] = false;
166                 break;
167         case NFSD_TEST:
168                 return nfsd_supported_minorversions[minorversion];
169         case NFSD_AVAIL:
170                 return minorversion <= NFSD_SUPPORTED_MINOR_VERSION;
171         }
172         return 0;
173 }
174 
175 /*
176  * Maximum number of nfsd processes
177  */
178 #define NFSD_MAXSERVS           8192
179 
180 int nfsd_nrthreads(struct net *net)
181 {
182         int rv = 0;
183         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
184 
185         mutex_lock(&nfsd_mutex);
186         if (nn->nfsd_serv)
187                 rv = nn->nfsd_serv->sv_nrthreads;
188         mutex_unlock(&nfsd_mutex);
189         return rv;
190 }
191 
192 static int nfsd_init_socks(struct net *net)
193 {
194         int error;
195         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
196 
197         if (!list_empty(&nn->nfsd_serv->sv_permsocks))
198                 return 0;
199 
200         error = svc_create_xprt(nn->nfsd_serv, "udp", net, PF_INET, NFS_PORT,
201                                         SVC_SOCK_DEFAULTS);
202         if (error < 0)
203                 return error;
204 
205         error = svc_create_xprt(nn->nfsd_serv, "tcp", net, PF_INET, NFS_PORT,
206                                         SVC_SOCK_DEFAULTS);
207         if (error < 0)
208                 return error;
209 
210         return 0;
211 }
212 
213 static int nfsd_users = 0;
214 
215 static int nfsd_startup_generic(int nrservs)
216 {
217         int ret;
218 
219         if (nfsd_users++)
220                 return 0;
221 
222         /*
223          * Readahead param cache - will no-op if it already exists.
224          * (Note therefore results will be suboptimal if number of
225          * threads is modified after nfsd start.)
226          */
227         ret = nfsd_racache_init(2*nrservs);
228         if (ret)
229                 goto dec_users;
230 
231         ret = nfs4_state_start();
232         if (ret)
233                 goto out_racache;
234         return 0;
235 
236 out_racache:
237         nfsd_racache_shutdown();
238 dec_users:
239         nfsd_users--;
240         return ret;
241 }
242 
243 static void nfsd_shutdown_generic(void)
244 {
245         if (--nfsd_users)
246                 return;
247 
248         nfs4_state_shutdown();
249         nfsd_racache_shutdown();
250 }
251 
252 static bool nfsd_needs_lockd(void)
253 {
254 #if defined(CONFIG_NFSD_V3)
255         return (nfsd_versions[2] != NULL) || (nfsd_versions[3] != NULL);
256 #else
257         return (nfsd_versions[2] != NULL);
258 #endif
259 }
260 
261 static int nfsd_startup_net(int nrservs, struct net *net)
262 {
263         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
264         int ret;
265 
266         if (nn->nfsd_net_up)
267                 return 0;
268 
269         ret = nfsd_startup_generic(nrservs);
270         if (ret)
271                 return ret;
272         ret = nfsd_init_socks(net);
273         if (ret)
274                 goto out_socks;
275 
276         if (nfsd_needs_lockd() && !nn->lockd_up) {
277                 ret = lockd_up(net);
278                 if (ret)
279                         goto out_socks;
280                 nn->lockd_up = 1;
281         }
282 
283         ret = nfs4_state_start_net(net);
284         if (ret)
285                 goto out_lockd;
286 
287         nn->nfsd_net_up = true;
288         return 0;
289 
290 out_lockd:
291         if (nn->lockd_up) {
292                 lockd_down(net);
293                 nn->lockd_up = 0;
294         }
295 out_socks:
296         nfsd_shutdown_generic();
297         return ret;
298 }
299 
300 static void nfsd_shutdown_net(struct net *net)
301 {
302         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
303 
304         nfs4_state_shutdown_net(net);
305         if (nn->lockd_up) {
306                 lockd_down(net);
307                 nn->lockd_up = 0;
308         }
309         nn->nfsd_net_up = false;
310         nfsd_shutdown_generic();
311 }
312 
313 static int nfsd_inetaddr_event(struct notifier_block *this, unsigned long event,
314         void *ptr)
315 {
316         struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;
317         struct net_device *dev = ifa->ifa_dev->dev;
318         struct net *net = dev_net(dev);
319         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
320         struct sockaddr_in sin;
321 
322         if (event != NETDEV_DOWN)
323                 goto out;
324 
325         if (nn->nfsd_serv) {
326                 dprintk("nfsd_inetaddr_event: removed %pI4\n", &ifa->ifa_local);
327                 sin.sin_family = AF_INET;
328                 sin.sin_addr.s_addr = ifa->ifa_local;
329                 svc_age_temp_xprts_now(nn->nfsd_serv, (struct sockaddr *)&sin);
330         }
331 
332 out:
333         return NOTIFY_DONE;
334 }
335 
336 static struct notifier_block nfsd_inetaddr_notifier = {
337         .notifier_call = nfsd_inetaddr_event,
338 };
339 
340 #if IS_ENABLED(CONFIG_IPV6)
341 static int nfsd_inet6addr_event(struct notifier_block *this,
342         unsigned long event, void *ptr)
343 {
344         struct inet6_ifaddr *ifa = (struct inet6_ifaddr *)ptr;
345         struct net_device *dev = ifa->idev->dev;
346         struct net *net = dev_net(dev);
347         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
348         struct sockaddr_in6 sin6;
349 
350         if (event != NETDEV_DOWN)
351                 goto out;
352 
353         if (nn->nfsd_serv) {
354                 dprintk("nfsd_inet6addr_event: removed %pI6\n", &ifa->addr);
355                 sin6.sin6_family = AF_INET6;
356                 sin6.sin6_addr = ifa->addr;
357                 svc_age_temp_xprts_now(nn->nfsd_serv, (struct sockaddr *)&sin6);
358         }
359 
360 out:
361         return NOTIFY_DONE;
362 }
363 
364 static struct notifier_block nfsd_inet6addr_notifier = {
365         .notifier_call = nfsd_inet6addr_event,
366 };
367 #endif
368 
369 static void nfsd_last_thread(struct svc_serv *serv, struct net *net)
370 {
371         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
372 
373         unregister_inetaddr_notifier(&nfsd_inetaddr_notifier);
374 #if IS_ENABLED(CONFIG_IPV6)
375         unregister_inet6addr_notifier(&nfsd_inet6addr_notifier);
376 #endif
377         /*
378          * write_ports can create the server without actually starting
379          * any threads--if we get shut down before any threads are
380          * started, then nfsd_last_thread will be run before any of this
381          * other initialization has been done except the rpcb information.
382          */
383         svc_rpcb_cleanup(serv, net);
384         if (!nn->nfsd_net_up)
385                 return;
386 
387         nfsd_shutdown_net(net);
388         printk(KERN_WARNING "nfsd: last server has exited, flushing export "
389                             "cache\n");
390         nfsd_export_flush(net);
391 }
392 
393 void nfsd_reset_versions(void)
394 {
395         int found_one = 0;
396         int i;
397 
398         for (i = NFSD_MINVERS; i < NFSD_NRVERS; i++) {
399                 if (nfsd_program.pg_vers[i])
400                         found_one = 1;
401         }
402 
403         if (!found_one) {
404                 for (i = NFSD_MINVERS; i < NFSD_NRVERS; i++)
405                         nfsd_program.pg_vers[i] = nfsd_version[i];
406 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
407                 for (i = NFSD_ACL_MINVERS; i < NFSD_ACL_NRVERS; i++)
408                         nfsd_acl_program.pg_vers[i] =
409                                 nfsd_acl_version[i];
410 #endif
411         }
412 }
413 
414 /*
415  * Each session guarantees a negotiated per slot memory cache for replies
416  * which in turn consumes memory beyond the v2/v3/v4.0 server. A dedicated
417  * NFSv4.1 server might want to use more memory for a DRC than a machine
418  * with mutiple services.
419  *
420  * Impose a hard limit on the number of pages for the DRC which varies
421  * according to the machines free pages. This is of course only a default.
422  *
423  * For now this is a #defined shift which could be under admin control
424  * in the future.
425  */
426 static void set_max_drc(void)
427 {
428         #define NFSD_DRC_SIZE_SHIFT     10
429         nfsd_drc_max_mem = (nr_free_buffer_pages()
430                                         >> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE;
431         nfsd_drc_mem_used = 0;
432         spin_lock_init(&nfsd_drc_lock);
433         dprintk("%s nfsd_drc_max_mem %lu \n", __func__, nfsd_drc_max_mem);
434 }
435 
436 static int nfsd_get_default_max_blksize(void)
437 {
438         struct sysinfo i;
439         unsigned long long target;
440         unsigned long ret;
441 
442         si_meminfo(&i);
443         target = (i.totalram - i.totalhigh) << PAGE_SHIFT;
444         /*
445          * Aim for 1/4096 of memory per thread This gives 1MB on 4Gig
446          * machines, but only uses 32K on 128M machines.  Bottom out at
447          * 8K on 32M and smaller.  Of course, this is only a default.
448          */
449         target >>= 12;
450 
451         ret = NFSSVC_MAXBLKSIZE;
452         while (ret > target && ret >= 8*1024*2)
453                 ret /= 2;
454         return ret;
455 }
456 
457 static struct svc_serv_ops nfsd_thread_sv_ops = {
458         .svo_shutdown           = nfsd_last_thread,
459         .svo_function           = nfsd,
460         .svo_enqueue_xprt       = svc_xprt_do_enqueue,
461         .svo_setup              = svc_set_num_threads,
462         .svo_module             = THIS_MODULE,
463 };
464 
465 int nfsd_create_serv(struct net *net)
466 {
467         int error;
468         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
469 
470         WARN_ON(!mutex_is_locked(&nfsd_mutex));
471         if (nn->nfsd_serv) {
472                 svc_get(nn->nfsd_serv);
473                 return 0;
474         }
475         if (nfsd_max_blksize == 0)
476                 nfsd_max_blksize = nfsd_get_default_max_blksize();
477         nfsd_reset_versions();
478         nn->nfsd_serv = svc_create_pooled(&nfsd_program, nfsd_max_blksize,
479                                                 &nfsd_thread_sv_ops);
480         if (nn->nfsd_serv == NULL)
481                 return -ENOMEM;
482 
483         nn->nfsd_serv->sv_maxconn = nn->max_connections;
484         error = svc_bind(nn->nfsd_serv, net);
485         if (error < 0) {
486                 svc_destroy(nn->nfsd_serv);
487                 return error;
488         }
489 
490         set_max_drc();
491         register_inetaddr_notifier(&nfsd_inetaddr_notifier);
492 #if IS_ENABLED(CONFIG_IPV6)
493         register_inet6addr_notifier(&nfsd_inet6addr_notifier);
494 #endif
495         do_gettimeofday(&nn->nfssvc_boot);              /* record boot time */
496         return 0;
497 }
498 
499 int nfsd_nrpools(struct net *net)
500 {
501         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
502 
503         if (nn->nfsd_serv == NULL)
504                 return 0;
505         else
506                 return nn->nfsd_serv->sv_nrpools;
507 }
508 
509 int nfsd_get_nrthreads(int n, int *nthreads, struct net *net)
510 {
511         int i = 0;
512         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
513 
514         if (nn->nfsd_serv != NULL) {
515                 for (i = 0; i < nn->nfsd_serv->sv_nrpools && i < n; i++)
516                         nthreads[i] = nn->nfsd_serv->sv_pools[i].sp_nrthreads;
517         }
518 
519         return 0;
520 }
521 
522 void nfsd_destroy(struct net *net)
523 {
524         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
525         int destroy = (nn->nfsd_serv->sv_nrthreads == 1);
526 
527         if (destroy)
528                 svc_shutdown_net(nn->nfsd_serv, net);
529         svc_destroy(nn->nfsd_serv);
530         if (destroy)
531                 nn->nfsd_serv = NULL;
532 }
533 
534 int nfsd_set_nrthreads(int n, int *nthreads, struct net *net)
535 {
536         int i = 0;
537         int tot = 0;
538         int err = 0;
539         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
540 
541         WARN_ON(!mutex_is_locked(&nfsd_mutex));
542 
543         if (nn->nfsd_serv == NULL || n <= 0)
544                 return 0;
545 
546         if (n > nn->nfsd_serv->sv_nrpools)
547                 n = nn->nfsd_serv->sv_nrpools;
548 
549         /* enforce a global maximum number of threads */
550         tot = 0;
551         for (i = 0; i < n; i++) {
552                 nthreads[i] = min(nthreads[i], NFSD_MAXSERVS);
553                 tot += nthreads[i];
554         }
555         if (tot > NFSD_MAXSERVS) {
556                 /* total too large: scale down requested numbers */
557                 for (i = 0; i < n && tot > 0; i++) {
558                         int new = nthreads[i] * NFSD_MAXSERVS / tot;
559                         tot -= (nthreads[i] - new);
560                         nthreads[i] = new;
561                 }
562                 for (i = 0; i < n && tot > 0; i++) {
563                         nthreads[i]--;
564                         tot--;
565                 }
566         }
567 
568         /*
569          * There must always be a thread in pool 0; the admin
570          * can't shut down NFS completely using pool_threads.
571          */
572         if (nthreads[0] == 0)
573                 nthreads[0] = 1;
574 
575         /* apply the new numbers */
576         svc_get(nn->nfsd_serv);
577         for (i = 0; i < n; i++) {
578                 err = nn->nfsd_serv->sv_ops->svo_setup(nn->nfsd_serv,
579                                 &nn->nfsd_serv->sv_pools[i], nthreads[i]);
580                 if (err)
581                         break;
582         }
583         nfsd_destroy(net);
584         return err;
585 }
586 
587 /*
588  * Adjust the number of threads and return the new number of threads.
589  * This is also the function that starts the server if necessary, if
590  * this is the first time nrservs is nonzero.
591  */
592 int
593 nfsd_svc(int nrservs, struct net *net)
594 {
595         int     error;
596         bool    nfsd_up_before;
597         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
598 
599         mutex_lock(&nfsd_mutex);
600         dprintk("nfsd: creating service\n");
601 
602         nrservs = max(nrservs, 0);
603         nrservs = min(nrservs, NFSD_MAXSERVS);
604         error = 0;
605 
606         if (nrservs == 0 && nn->nfsd_serv == NULL)
607                 goto out;
608 
609         error = nfsd_create_serv(net);
610         if (error)
611                 goto out;
612 
613         nfsd_up_before = nn->nfsd_net_up;
614 
615         error = nfsd_startup_net(nrservs, net);
616         if (error)
617                 goto out_destroy;
618         error = nn->nfsd_serv->sv_ops->svo_setup(nn->nfsd_serv,
619                         NULL, nrservs);
620         if (error)
621                 goto out_shutdown;
622         /* We are holding a reference to nn->nfsd_serv which
623          * we don't want to count in the return value,
624          * so subtract 1
625          */
626         error = nn->nfsd_serv->sv_nrthreads - 1;
627 out_shutdown:
628         if (error < 0 && !nfsd_up_before)
629                 nfsd_shutdown_net(net);
630 out_destroy:
631         nfsd_destroy(net);              /* Release server */
632 out:
633         mutex_unlock(&nfsd_mutex);
634         return error;
635 }
636 
637 
638 /*
639  * This is the NFS server kernel thread
640  */
641 static int
642 nfsd(void *vrqstp)
643 {
644         struct svc_rqst *rqstp = (struct svc_rqst *) vrqstp;
645         struct svc_xprt *perm_sock = list_entry(rqstp->rq_server->sv_permsocks.next, typeof(struct svc_xprt), xpt_list);
646         struct net *net = perm_sock->xpt_net;
647         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
648         int err;
649 
650         /* Lock module and set up kernel thread */
651         mutex_lock(&nfsd_mutex);
652 
653         /* At this point, the thread shares current->fs
654          * with the init process. We need to create files with a
655          * umask of 0 instead of init's umask. */
656         if (unshare_fs_struct() < 0) {
657                 printk("Unable to start nfsd thread: out of memory\n");
658                 goto out;
659         }
660 
661         current->fs->umask = 0;
662 
663         /*
664          * thread is spawned with all signals set to SIG_IGN, re-enable
665          * the ones that will bring down the thread
666          */
667         allow_signal(SIGKILL);
668         allow_signal(SIGHUP);
669         allow_signal(SIGINT);
670         allow_signal(SIGQUIT);
671 
672         nfsdstats.th_cnt++;
673         mutex_unlock(&nfsd_mutex);
674 
675         set_freezable();
676 
677         /*
678          * The main request loop
679          */
680         for (;;) {
681                 /* Update sv_maxconn if it has changed */
682                 rqstp->rq_server->sv_maxconn = nn->max_connections;
683 
684                 /*
685                  * Find a socket with data available and call its
686                  * recvfrom routine.
687                  */
688                 while ((err = svc_recv(rqstp, 60*60*HZ)) == -EAGAIN)
689                         ;
690                 if (err == -EINTR)
691                         break;
692                 validate_process_creds();
693                 svc_process(rqstp);
694                 validate_process_creds();
695         }
696 
697         /* Clear signals before calling svc_exit_thread() */
698         flush_signals(current);
699 
700         mutex_lock(&nfsd_mutex);
701         nfsdstats.th_cnt --;
702 
703 out:
704         rqstp->rq_server = NULL;
705 
706         /* Release the thread */
707         svc_exit_thread(rqstp);
708 
709         nfsd_destroy(net);
710 
711         /* Release module */
712         mutex_unlock(&nfsd_mutex);
713         module_put_and_exit(0);
714         return 0;
715 }
716 
717 static __be32 map_new_errors(u32 vers, __be32 nfserr)
718 {
719         if (nfserr == nfserr_jukebox && vers == 2)
720                 return nfserr_dropit;
721         if (nfserr == nfserr_wrongsec && vers < 4)
722                 return nfserr_acces;
723         return nfserr;
724 }
725 
726 int
727 nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
728 {
729         struct svc_procedure    *proc;
730         kxdrproc_t              xdr;
731         __be32                  nfserr;
732         __be32                  *nfserrp;
733 
734         dprintk("nfsd_dispatch: vers %d proc %d\n",
735                                 rqstp->rq_vers, rqstp->rq_proc);
736         proc = rqstp->rq_procinfo;
737 
738         /*
739          * Give the xdr decoder a chance to change this if it wants
740          * (necessary in the NFSv4.0 compound case)
741          */
742         rqstp->rq_cachetype = proc->pc_cachetype;
743         /* Decode arguments */
744         xdr = proc->pc_decode;
745         if (xdr && !xdr(rqstp, (__be32*)rqstp->rq_arg.head[0].iov_base,
746                         rqstp->rq_argp)) {
747                 dprintk("nfsd: failed to decode arguments!\n");
748                 *statp = rpc_garbage_args;
749                 return 1;
750         }
751 
752         /* Check whether we have this call in the cache. */
753         switch (nfsd_cache_lookup(rqstp)) {
754         case RC_DROPIT:
755                 return 0;
756         case RC_REPLY:
757                 return 1;
758         case RC_DOIT:;
759                 /* do it */
760         }
761 
762         /* need to grab the location to store the status, as
763          * nfsv4 does some encoding while processing 
764          */
765         nfserrp = rqstp->rq_res.head[0].iov_base
766                 + rqstp->rq_res.head[0].iov_len;
767         rqstp->rq_res.head[0].iov_len += sizeof(__be32);
768 
769         /* Now call the procedure handler, and encode NFS status. */
770         nfserr = proc->pc_func(rqstp, rqstp->rq_argp, rqstp->rq_resp);
771         nfserr = map_new_errors(rqstp->rq_vers, nfserr);
772         if (nfserr == nfserr_dropit || test_bit(RQ_DROPME, &rqstp->rq_flags)) {
773                 dprintk("nfsd: Dropping request; may be revisited later\n");
774                 nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
775                 return 0;
776         }
777 
778         if (rqstp->rq_proc != 0)
779                 *nfserrp++ = nfserr;
780 
781         /* Encode result.
782          * For NFSv2, additional info is never returned in case of an error.
783          */
784         if (!(nfserr && rqstp->rq_vers == 2)) {
785                 xdr = proc->pc_encode;
786                 if (xdr && !xdr(rqstp, nfserrp,
787                                 rqstp->rq_resp)) {
788                         /* Failed to encode result. Release cache entry */
789                         dprintk("nfsd: failed to encode result!\n");
790                         nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
791                         *statp = rpc_system_err;
792                         return 1;
793                 }
794         }
795 
796         /* Store reply in cache. */
797         nfsd_cache_update(rqstp, rqstp->rq_cachetype, statp + 1);
798         return 1;
799 }
800 
801 int nfsd_pool_stats_open(struct inode *inode, struct file *file)
802 {
803         int ret;
804         struct nfsd_net *nn = net_generic(inode->i_sb->s_fs_info, nfsd_net_id);
805 
806         mutex_lock(&nfsd_mutex);
807         if (nn->nfsd_serv == NULL) {
808                 mutex_unlock(&nfsd_mutex);
809                 return -ENODEV;
810         }
811         /* bump up the psudo refcount while traversing */
812         svc_get(nn->nfsd_serv);
813         ret = svc_pool_stats_open(nn->nfsd_serv, file);
814         mutex_unlock(&nfsd_mutex);
815         return ret;
816 }
817 
818 int nfsd_pool_stats_release(struct inode *inode, struct file *file)
819 {
820         int ret = seq_release(inode, file);
821         struct net *net = inode->i_sb->s_fs_info;
822 
823         mutex_lock(&nfsd_mutex);
824         /* this function really, really should have been called svc_put() */
825         nfsd_destroy(net);
826         mutex_unlock(&nfsd_mutex);
827         return ret;
828 }
829 

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