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 #include <linux/nsproxy.h>
  15
  16 #include <linux/sunrpc/stats.h>
  17 #include <linux/sunrpc/svcsock.h>
  18 #include <linux/lockd/bind.h>
  19 #include <linux/nfsacl.h>
  20 #include <linux/seq_file.h>
  21 #include <net/net_namespace.h>
  22 #include "nfsd.h"
  23 #include "cache.h"
  24 #include "vfs.h"
  25
  26 #define NFSDDBG_FACILITY        NFSDDBG_SVC
  27
  28 extern struct svc_program       nfsd_program;
  29 static int                      nfsd(void *vrqstp);
  30 struct timeval                  nfssvc_boot;
  31
  32 /*
  33  * nfsd_mutex protects nfsd_serv -- both the pointer itself and the members
  34  * of the svc_serv struct. In particular, ->sv_nrthreads but also to some
  35  * extent ->sv_temp_socks and ->sv_permsocks. It also protects nfsdstats.th_cnt
  36  *
  37  * If (out side the lock) nfsd_serv is non-NULL, then it must point to a
  38  * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0. That number
  39  * of nfsd threads must exist and each must listed in ->sp_all_threads in each
  40  * entry of ->sv_pools[].
  41  *
  42  * Transitions of the thread count between zero and non-zero are of particular
  43  * interest since the svc_serv needs to be created and initialized at that
  44  * point, or freed.
  45  *
  46  * Finally, the nfsd_mutex also protects some of the global variables that are
  47  * accessed when nfsd starts and that are settable via the write_* routines in
  48  * nfsctl.c. In particular:
  49  *
  50  *      user_recovery_dirname
  51  *      user_lease_time
  52  *      nfsd_versions
  53  */
  54 DEFINE_MUTEX(nfsd_mutex);
  55 struct svc_serv                 *nfsd_serv;
  56
  57 /*
  58  * nfsd_drc_lock protects nfsd_drc_max_pages and nfsd_drc_pages_used.
  59  * nfsd_drc_max_pages limits the total amount of memory available for
  60  * version 4.1 DRC caches.
  61  * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage.
  62  */
  63 spinlock_t      nfsd_drc_lock;
  64 unsigned int    nfsd_drc_max_mem;
  65 unsigned int    nfsd_drc_mem_used;
  66
  67 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
  68 static struct svc_stat  nfsd_acl_svcstats;
  69 static struct svc_version *     nfsd_acl_version[] = {
  70         [2] = &nfsd_acl_version2,
  71         [3] = &nfsd_acl_version3,
  72 };
  73
  74 #define NFSD_ACL_MINVERS            2
  75 #define NFSD_ACL_NRVERS         ARRAY_SIZE(nfsd_acl_version)
  76 static struct svc_version *nfsd_acl_versions[NFSD_ACL_NRVERS];
  77
  78 static struct svc_program       nfsd_acl_program = {
  79         .pg_prog                = NFS_ACL_PROGRAM,
  80         .pg_nvers               = NFSD_ACL_NRVERS,
  81         .pg_vers                = nfsd_acl_versions,
  82         .pg_name                = "nfsacl",
  83         .pg_class               = "nfsd",
  84         .pg_stats               = &nfsd_acl_svcstats,
  85         .pg_authenticate        = &svc_set_client,
  86 };
  87
  88 static struct svc_stat  nfsd_acl_svcstats = {
  89         .program        = &nfsd_acl_program,
  90 };
  91 #endif /* defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL) */
  92
  93 static struct svc_version *     nfsd_version[] = {
  94         [2] = &nfsd_version2,
  95 #if defined(CONFIG_NFSD_V3)
  96         [3] = &nfsd_version3,
  97 #endif
  98 #if defined(CONFIG_NFSD_V4)
  99         [4] = &nfsd_version4,
 100 #endif
 101 };
 102
 103 #define NFSD_MINVERS            2
 104 #define NFSD_NRVERS             ARRAY_SIZE(nfsd_version)
 105 static struct svc_version *nfsd_versions[NFSD_NRVERS];
 106
 107 struct svc_program              nfsd_program = {
 108 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
 109         .pg_next                = &nfsd_acl_program,
 110 #endif
 111         .pg_prog                = NFS_PROGRAM,          /* program number */
 112         .pg_nvers               = NFSD_NRVERS,          /* nr of entries in nfsd_version */
 113         .pg_vers                = nfsd_versions,        /* version table */
 114         .pg_name                = "nfsd",               /* program name */
 115         .pg_class               = "nfsd",               /* authentication class */
 116         .pg_stats               = &nfsd_svcstats,       /* version table */
 117         .pg_authenticate        = &svc_set_client,      /* export authentication */
 118
 119 };
 120
 121 u32 nfsd_supported_minorversion;
 122
 123 int nfsd_vers(int vers, enum vers_op change)
 124 {
 125         if (vers < NFSD_MINVERS || vers >= NFSD_NRVERS)
 126                 return 0;
 127         switch(change) {
 128         case NFSD_SET:
 129                 nfsd_versions[vers] = nfsd_version[vers];
 130 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
 131                 if (vers < NFSD_ACL_NRVERS)
 132                         nfsd_acl_versions[vers] = nfsd_acl_version[vers];
 133 #endif
 134                 break;
 135         case NFSD_CLEAR:
 136                 nfsd_versions[vers] = NULL;
 137 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
 138                 if (vers < NFSD_ACL_NRVERS)
 139                         nfsd_acl_versions[vers] = NULL;
 140 #endif
 141                 break;
 142         case NFSD_TEST:
 143                 return nfsd_versions[vers] != NULL;
 144         case NFSD_AVAIL:
 145                 return nfsd_version[vers] != NULL;
 146         }
 147         return 0;
 148 }
 149
 150 int nfsd_minorversion(u32 minorversion, enum vers_op change)
 151 {
 152         if (minorversion > NFSD_SUPPORTED_MINOR_VERSION)
 153                 return -1;
 154         switch(change) {
 155         case NFSD_SET:
 156                 nfsd_supported_minorversion = minorversion;
 157                 break;
 158         case NFSD_CLEAR:
 159                 if (minorversion == 0)
 160                         return -1;
 161                 nfsd_supported_minorversion = minorversion - 1;
 162                 break;
 163         case NFSD_TEST:
 164                 return minorversion <= nfsd_supported_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(void)
 177 {
 178         int rv = 0;
 179         mutex_lock(&nfsd_mutex);
 180         if (nfsd_serv)
 181                 rv = nfsd_serv->sv_nrthreads;
 182         mutex_unlock(&nfsd_mutex);
 183         return rv;
 184 }
 185
 186 static int nfsd_init_socks(void)
 187 {
 188         int error;
 189         if (!list_empty(&nfsd_serv->sv_permsocks))
 190                 return 0;
 191
 192         error = svc_create_xprt(nfsd_serv, "udp", &init_net, PF_INET, NFS_PORT,
 193                                         SVC_SOCK_DEFAULTS);
 194         if (error < 0)
 195                 return error;
 196
 197         error = svc_create_xprt(nfsd_serv, "tcp", &init_net, PF_INET, NFS_PORT,
 198                                         SVC_SOCK_DEFAULTS);
 199         if (error < 0)
 200                 return error;
 201
 202         return 0;
 203 }
 204
 205 static bool nfsd_up = false;
 206
 207 static int nfsd_startup(int nrservs)
 208 {
 209         int ret;
 210
 211         if (nfsd_up)
 212                 return 0;
 213         /*
 214          * Readahead param cache - will no-op if it already exists.
 215          * (Note therefore results will be suboptimal if number of
 216          * threads is modified after nfsd start.)
 217          */
 218         ret = nfsd_racache_init(2*nrservs);
 219         if (ret)
 220                 return ret;
 221         ret = nfsd_init_socks();
 222         if (ret)
 223                 goto out_racache;
 224         ret = lockd_up(&init_net);
 225         if (ret)
 226                 goto out_racache;
 227         ret = nfs4_state_start();
 228         if (ret)
 229                 goto out_lockd;
 230         nfsd_up = true;
 231         return 0;
 232 out_lockd:
 233         lockd_down(&init_net);
 234 out_racache:
 235         nfsd_racache_shutdown();
 236         return ret;
 237 }
 238
 239 static void nfsd_shutdown(void)
 240 {
 241         /*
 242          * write_ports can create the server without actually starting
 243          * any threads--if we get shut down before any threads are
 244          * started, then nfsd_last_thread will be run before any of this
 245          * other initialization has been done.
 246          */
 247         if (!nfsd_up)
 248                 return;
 249         nfs4_state_shutdown();
 250         lockd_down(&init_net);
 251         nfsd_racache_shutdown();
 252         nfsd_up = false;
 253 }
 254
 255 static void nfsd_last_thread(struct svc_serv *serv, struct net *net)
 256 {
 257         nfsd_shutdown();
 258
 259         svc_rpcb_cleanup(serv, net);
 260
 261         printk(KERN_WARNING "nfsd: last server has exited, flushing export "
 262                             "cache\n");
 263         nfsd_export_flush(net);
 264 }
 265
 266 void nfsd_reset_versions(void)
 267 {
 268         int found_one = 0;
 269         int i;
 270
 271         for (i = NFSD_MINVERS; i < NFSD_NRVERS; i++) {
 272                 if (nfsd_program.pg_vers[i])
 273                         found_one = 1;
 274         }
 275
 276         if (!found_one) {
 277                 for (i = NFSD_MINVERS; i < NFSD_NRVERS; i++)
 278                         nfsd_program.pg_vers[i] = nfsd_version[i];
 279 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
 280                 for (i = NFSD_ACL_MINVERS; i < NFSD_ACL_NRVERS; i++)
 281                         nfsd_acl_program.pg_vers[i] =
 282                                 nfsd_acl_version[i];
 283 #endif
 284         }
 285 }
 286
 287 /*
 288  * Each session guarantees a negotiated per slot memory cache for replies
 289  * which in turn consumes memory beyond the v2/v3/v4.0 server. A dedicated
 290  * NFSv4.1 server might want to use more memory for a DRC than a machine
 291  * with mutiple services.
 292  *
 293  * Impose a hard limit on the number of pages for the DRC which varies
 294  * according to the machines free pages. This is of course only a default.
 295  *
 296  * For now this is a #defined shift which could be under admin control
 297  * in the future.
 298  */
 299 static void set_max_drc(void)
 300 {
 301         #define NFSD_DRC_SIZE_SHIFT     10
 302         nfsd_drc_max_mem = (nr_free_buffer_pages()
 303                                         >> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE;
 304         nfsd_drc_mem_used = 0;
 305         spin_lock_init(&nfsd_drc_lock);
 306         dprintk("%s nfsd_drc_max_mem %u \n", __func__, nfsd_drc_max_mem);
 307 }
 308
 309 static int nfsd_get_default_max_blksize(void)
 310 {
 311         struct sysinfo i;
 312         unsigned long long target;
 313         unsigned long ret;
 314
 315         si_meminfo(&i);
 316         target = (i.totalram - i.totalhigh) << PAGE_SHIFT;
 317         /*
 318          * Aim for 1/4096 of memory per thread This gives 1MB on 4Gig
 319          * machines, but only uses 32K on 128M machines.  Bottom out at
 320          * 8K on 32M and smaller.  Of course, this is only a default.
 321          */
 322         target >>= 12;
 323
 324         ret = NFSSVC_MAXBLKSIZE;
 325         while (ret > target && ret >= 8*1024*2)
 326                 ret /= 2;
 327         return ret;
 328 }
 329
 330 int nfsd_create_serv(void)
 331 {
 332         int error;
 333         struct net *net = current->nsproxy->net_ns;
 334
 335         WARN_ON(!mutex_is_locked(&nfsd_mutex));
 336         if (nfsd_serv) {
 337                 svc_get(nfsd_serv);
 338                 return 0;
 339         }
 340         if (nfsd_max_blksize == 0)
 341                 nfsd_max_blksize = nfsd_get_default_max_blksize();
 342         nfsd_reset_versions();
 343         nfsd_serv = svc_create_pooled(&nfsd_program, nfsd_max_blksize,
 344                                       nfsd_last_thread, nfsd, THIS_MODULE);
 345         if (nfsd_serv == NULL)
 346                 return -ENOMEM;
 347
 348         error = svc_bind(nfsd_serv, net);
 349         if (error < 0) {
 350                 svc_destroy(nfsd_serv);
 351                 return error;
 352         }
 353
 354         set_max_drc();
 355         do_gettimeofday(&nfssvc_boot);          /* record boot time */
 356         return 0;
 357 }
 358
 359 int nfsd_nrpools(void)
 360 {
 361         if (nfsd_serv == NULL)
 362                 return 0;
 363         else
 364                 return nfsd_serv->sv_nrpools;
 365 }
 366
 367 int nfsd_get_nrthreads(int n, int *nthreads)
 368 {
 369         int i = 0;
 370
 371         if (nfsd_serv != NULL) {
 372                 for (i = 0; i < nfsd_serv->sv_nrpools && i < n; i++)
 373                         nthreads[i] = nfsd_serv->sv_pools[i].sp_nrthreads;
 374         }
 375
 376         return 0;
 377 }
 378
 379 int nfsd_set_nrthreads(int n, int *nthreads)
 380 {
 381         int i = 0;
 382         int tot = 0;
 383         int err = 0;
 384         struct net *net = &init_net;
 385
 386         WARN_ON(!mutex_is_locked(&nfsd_mutex));
 387
 388         if (nfsd_serv == NULL || n <= 0)
 389                 return 0;
 390
 391         if (n > nfsd_serv->sv_nrpools)
 392                 n = nfsd_serv->sv_nrpools;
 393
 394         /* enforce a global maximum number of threads */
 395         tot = 0;
 396         for (i = 0; i < n; i++) {
 397                 if (nthreads[i] > NFSD_MAXSERVS)
 398                         nthreads[i] = NFSD_MAXSERVS;
 399                 tot += nthreads[i];
 400         }
 401         if (tot > NFSD_MAXSERVS) {
 402                 /* total too large: scale down requested numbers */
 403                 for (i = 0; i < n && tot > 0; i++) {
 404                         int new = nthreads[i] * NFSD_MAXSERVS / tot;
 405                         tot -= (nthreads[i] - new);
 406                         nthreads[i] = new;
 407                 }
 408                 for (i = 0; i < n && tot > 0; i++) {
 409                         nthreads[i]--;
 410                         tot--;
 411                 }
 412         }
 413
 414         /*
 415          * There must always be a thread in pool 0; the admin
 416          * can't shut down NFS completely using pool_threads.
 417          */
 418         if (nthreads[0] == 0)
 419                 nthreads[0] = 1;
 420
 421         /* apply the new numbers */
 422         svc_get(nfsd_serv);
 423         for (i = 0; i < n; i++) {
 424                 err = svc_set_num_threads(nfsd_serv, &nfsd_serv->sv_pools[i],
 425                                           nthreads[i]);
 426                 if (err)
 427                         break;
 428         }
 429         nfsd_destroy(net);
 430         return err;
 431 }
 432
 433 /*
 434  * Adjust the number of threads and return the new number of threads.
 435  * This is also the function that starts the server if necessary, if
 436  * this is the first time nrservs is nonzero.
 437  */
 438 int
 439 nfsd_svc(int nrservs)
 440 {
 441         int     error;
 442         bool    nfsd_up_before;
 443         struct net *net = &init_net;
 444
 445         mutex_lock(&nfsd_mutex);
 446         dprintk("nfsd: creating service\n");
 447         if (nrservs <= 0)
 448                 nrservs = 0;
 449         if (nrservs > NFSD_MAXSERVS)
 450                 nrservs = NFSD_MAXSERVS;
 451         error = 0;
 452         if (nrservs == 0 && nfsd_serv == NULL)
 453                 goto out;
 454
 455         error = nfsd_create_serv();
 456         if (error)
 457                 goto out;
 458
 459         nfsd_up_before = nfsd_up;
 460
 461         error = nfsd_startup(nrservs);
 462         if (error)
 463                 goto out_destroy;
 464         error = svc_set_num_threads(nfsd_serv, NULL, nrservs);
 465         if (error)
 466                 goto out_shutdown;
 467         /* We are holding a reference to nfsd_serv which
 468          * we don't want to count in the return value,
 469          * so subtract 1
 470          */
 471         error = nfsd_serv->sv_nrthreads - 1;
 472 out_shutdown:
 473         if (error < 0 && !nfsd_up_before)
 474                 nfsd_shutdown();
 475 out_destroy:
 476         nfsd_destroy(net);              /* Release server */
 477 out:
 478         mutex_unlock(&nfsd_mutex);
 479         return error;
 480 }
 481
 482
 483 /*
 484  * This is the NFS server kernel thread
 485  */
 486 static int
 487 nfsd(void *vrqstp)
 488 {
 489         struct svc_rqst *rqstp = (struct svc_rqst *) vrqstp;
 490         int err;
 491
 492         /* Lock module and set up kernel thread */
 493         mutex_lock(&nfsd_mutex);
 494
 495         /* At this point, the thread shares current->fs
 496          * with the init process. We need to create files with a
 497          * umask of 0 instead of init's umask. */
 498         if (unshare_fs_struct() < 0) {
 499                 printk("Unable to start nfsd thread: out of memory\n");
 500                 goto out;
 501         }
 502
 503         current->fs->umask = 0;
 504
 505         /*
 506          * thread is spawned with all signals set to SIG_IGN, re-enable
 507          * the ones that will bring down the thread
 508          */
 509         allow_signal(SIGKILL);
 510         allow_signal(SIGHUP);
 511         allow_signal(SIGINT);
 512         allow_signal(SIGQUIT);
 513
 514         nfsdstats.th_cnt++;
 515         mutex_unlock(&nfsd_mutex);
 516
 517         /*
 518          * We want less throttling in balance_dirty_pages() so that nfs to
 519          * localhost doesn't cause nfsd to lock up due to all the client's
 520          * dirty pages.
 521          */
 522         current->flags |= PF_LESS_THROTTLE;
 523         set_freezable();
 524
 525         /*
 526          * The main request loop
 527          */
 528         for (;;) {
 529                 /*
 530                  * Find a socket with data available and call its
 531                  * recvfrom routine.
 532                  */
 533                 while ((err = svc_recv(rqstp, 60*60*HZ)) == -EAGAIN)
 534                         ;
 535                 if (err == -EINTR)
 536                         break;
 537                 validate_process_creds();
 538                 svc_process(rqstp);
 539                 validate_process_creds();
 540         }
 541
 542         /* Clear signals before calling svc_exit_thread() */
 543         flush_signals(current);
 544
 545         mutex_lock(&nfsd_mutex);
 546         nfsdstats.th_cnt --;
 547
 548 out:
 549         rqstp->rq_server = NULL;
 550
 551         /* Release the thread */
 552         svc_exit_thread(rqstp);
 553
 554         nfsd_destroy(&init_net);
 555
 556         /* Release module */
 557         mutex_unlock(&nfsd_mutex);
 558         module_put_and_exit(0);
 559         return 0;
 560 }
 561
 562 static __be32 map_new_errors(u32 vers, __be32 nfserr)
 563 {
 564         if (nfserr == nfserr_jukebox && vers == 2)
 565                 return nfserr_dropit;
 566         if (nfserr == nfserr_wrongsec && vers < 4)
 567                 return nfserr_acces;
 568         return nfserr;
 569 }
 570
 571 int
 572 nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
 573 {
 574         struct svc_procedure    *proc;
 575         kxdrproc_t              xdr;
 576         __be32                  nfserr;
 577         __be32                  *nfserrp;
 578
 579         dprintk("nfsd_dispatch: vers %d proc %d\n",
 580                                 rqstp->rq_vers, rqstp->rq_proc);
 581         proc = rqstp->rq_procinfo;
 582
 583         /*
 584          * Give the xdr decoder a chance to change this if it wants
 585          * (necessary in the NFSv4.0 compound case)
 586          */
 587         rqstp->rq_cachetype = proc->pc_cachetype;
 588         /* Decode arguments */
 589         xdr = proc->pc_decode;
 590         if (xdr && !xdr(rqstp, (__be32*)rqstp->rq_arg.head[0].iov_base,
 591                         rqstp->rq_argp)) {
 592                 dprintk("nfsd: failed to decode arguments!\n");
 593                 *statp = rpc_garbage_args;
 594                 return 1;
 595         }
 596
 597         /* Check whether we have this call in the cache. */
 598         switch (nfsd_cache_lookup(rqstp)) {
 599         case RC_INTR:
 600         case RC_DROPIT:
 601                 return 0;
 602         case RC_REPLY:
 603                 return 1;
 604         case RC_DOIT:;
 605                 /* do it */
 606         }
 607
 608         /* need to grab the location to store the status, as
 609          * nfsv4 does some encoding while processing
 610          */
 611         nfserrp = rqstp->rq_res.head[0].iov_base
 612                 + rqstp->rq_res.head[0].iov_len;
 613         rqstp->rq_res.head[0].iov_len += sizeof(__be32);
 614
 615         /* Now call the procedure handler, and encode NFS status. */
 616         nfserr = proc->pc_func(rqstp, rqstp->rq_argp, rqstp->rq_resp);
 617         nfserr = map_new_errors(rqstp->rq_vers, nfserr);
 618         if (nfserr == nfserr_dropit || rqstp->rq_dropme) {
 619                 dprintk("nfsd: Dropping request; may be revisited later\n");
 620                 nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
 621                 return 0;
 622         }
 623
 624         if (rqstp->rq_proc != 0)
 625                 *nfserrp++ = nfserr;
 626
 627         /* Encode result.
 628          * For NFSv2, additional info is never returned in case of an error.
 629          */
 630         if (!(nfserr && rqstp->rq_vers == 2)) {
 631                 xdr = proc->pc_encode;
 632                 if (xdr && !xdr(rqstp, nfserrp,
 633                                 rqstp->rq_resp)) {
 634                         /* Failed to encode result. Release cache entry */
 635                         dprintk("nfsd: failed to encode result!\n");
 636                         nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
 637                         *statp = rpc_system_err;
 638                         return 1;
 639                 }
 640         }
 641
 642         /* Store reply in cache. */
 643         nfsd_cache_update(rqstp, proc->pc_cachetype, statp + 1);
 644         return 1;
 645 }
 646
 647 int nfsd_pool_stats_open(struct inode *inode, struct file *file)
 648 {
 649         int ret;
 650         mutex_lock(&nfsd_mutex);
 651         if (nfsd_serv == NULL) {
 652                 mutex_unlock(&nfsd_mutex);
 653                 return -ENODEV;
 654         }
 655         /* bump up the psudo refcount while traversing */
 656         svc_get(nfsd_serv);
 657         ret = svc_pool_stats_open(nfsd_serv, file);
 658         mutex_unlock(&nfsd_mutex);
 659         return ret;
 660 }
 661
 662 int nfsd_pool_stats_release(struct inode *inode, struct file *file)
 663 {
 664         int ret = seq_release(inode, file);
 665         struct net *net = &init_net;
 666
 667         mutex_lock(&nfsd_mutex);
 668         /* this function really, really should have been called svc_put() */
 669         nfsd_destroy(net);
 670         mutex_unlock(&nfsd_mutex);
 671         return ret;
 672 }