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

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