fs/nfsd/nfssvc.c

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