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