err.no Git - linux-2.6/blob - net/sunrpc/clnt.c

   1 /*
   2  *  linux/net/sunrpc/clnt.c
   3  *
   4  *  This file contains the high-level RPC interface.
   5  *  It is modeled as a finite state machine to support both synchronous
   6  *  and asynchronous requests.
   7  *
   8  *  -   RPC header generation and argument serialization.
   9  *  -   Credential refresh.
  10  *  -   TCP connect handling.
  11  *  -   Retry of operation when it is suspected the operation failed because
  12  *      of uid squashing on the server, or when the credentials were stale
  13  *      and need to be refreshed, or when a packet was damaged in transit.
  14  *      This may be have to be moved to the VFS layer.
  15  *
  16  *  NB: BSD uses a more intelligent approach to guessing when a request
  17  *  or reply has been lost by keeping the RTO estimate for each procedure.
  18  *  We currently make do with a constant timeout value.
  19  *
  20  *  Copyright (C) 1992,1993 Rick Sladkey <jrs@world.std.com>
  21  *  Copyright (C) 1995,1996 Olaf Kirch <okir@monad.swb.de>
  22  */
  23
  24 #include <asm/system.h>
  25
  26 #include <linux/module.h>
  27 #include <linux/types.h>
  28 #include <linux/mm.h>
  29 #include <linux/slab.h>
  30 #include <linux/utsname.h>
  31 #include <linux/workqueue.h>
  32
  33 #include <linux/sunrpc/clnt.h>
  34 #include <linux/sunrpc/rpc_pipe_fs.h>
  35 #include <linux/sunrpc/metrics.h>
  36
  37
  38 #define RPC_SLACK_SPACE         (1024)  /* total overkill */
  39
  40 #ifdef RPC_DEBUG
  41 # define RPCDBG_FACILITY        RPCDBG_CALL
  42 #endif
  43
  44 static DECLARE_WAIT_QUEUE_HEAD(destroy_wait);
  45
  46
  47 static void     call_start(struct rpc_task *task);
  48 static void     call_reserve(struct rpc_task *task);
  49 static void     call_reserveresult(struct rpc_task *task);
  50 static void     call_allocate(struct rpc_task *task);
  51 static void     call_encode(struct rpc_task *task);
  52 static void     call_decode(struct rpc_task *task);
  53 static void     call_bind(struct rpc_task *task);
  54 static void     call_bind_status(struct rpc_task *task);
  55 static void     call_transmit(struct rpc_task *task);
  56 static void     call_status(struct rpc_task *task);
  57 static void     call_transmit_status(struct rpc_task *task);
  58 static void     call_refresh(struct rpc_task *task);
  59 static void     call_refreshresult(struct rpc_task *task);
  60 static void     call_timeout(struct rpc_task *task);
  61 static void     call_connect(struct rpc_task *task);
  62 static void     call_connect_status(struct rpc_task *task);
  63 static u32 *    call_header(struct rpc_task *task);
  64 static u32 *    call_verify(struct rpc_task *task);
  65
  66
  67 static int
  68 rpc_setup_pipedir(struct rpc_clnt *clnt, char *dir_name)
  69 {
  70         static uint32_t clntid;
  71         int error;
  72
  73         clnt->cl_vfsmnt = ERR_PTR(-ENOENT);
  74         clnt->cl_dentry = ERR_PTR(-ENOENT);
  75         if (dir_name == NULL)
  76                 return 0;
  77
  78         clnt->cl_vfsmnt = rpc_get_mount();
  79         if (IS_ERR(clnt->cl_vfsmnt))
  80                 return PTR_ERR(clnt->cl_vfsmnt);
  81
  82         for (;;) {
  83                 snprintf(clnt->cl_pathname, sizeof(clnt->cl_pathname),
  84                                 "%s/clnt%x", dir_name,
  85                                 (unsigned int)clntid++);
  86                 clnt->cl_pathname[sizeof(clnt->cl_pathname) - 1] = '\0';
  87                 clnt->cl_dentry = rpc_mkdir(clnt->cl_pathname, clnt);
  88                 if (!IS_ERR(clnt->cl_dentry))
  89                         return 0;
  90                 error = PTR_ERR(clnt->cl_dentry);
  91                 if (error != -EEXIST) {
  92                         printk(KERN_INFO "RPC: Couldn't create pipefs entry %s, error %d\n",
  93                                         clnt->cl_pathname, error);
  94                         rpc_put_mount();
  95                         return error;
  96                 }
  97         }
  98 }
  99
 100 /*
 101  * Create an RPC client
 102  * FIXME: This should also take a flags argument (as in task->tk_flags).
 103  * It's called (among others) from pmap_create_client, which may in
 104  * turn be called by an async task. In this case, rpciod should not be
 105  * made to sleep too long.
 106  */
 107 struct rpc_clnt *
 108 rpc_new_client(struct rpc_xprt *xprt, char *servname,
 109                   struct rpc_program *program, u32 vers,
 110                   rpc_authflavor_t flavor)
 111 {
 112         struct rpc_version      *version;
 113         struct rpc_clnt         *clnt = NULL;
 114         struct rpc_auth         *auth;
 115         int err;
 116         int len;
 117
 118         dprintk("RPC: creating %s client for %s (xprt %p)\n",
 119                 program->name, servname, xprt);
 120
 121         err = -EINVAL;
 122         if (!xprt)
 123                 goto out_no_xprt;
 124         if (vers >= program->nrvers || !(version = program->version[vers]))
 125                 goto out_err;
 126
 127         err = -ENOMEM;
 128         clnt = kzalloc(sizeof(*clnt), GFP_KERNEL);
 129         if (!clnt)
 130                 goto out_err;
 131         atomic_set(&clnt->cl_users, 0);
 132         atomic_set(&clnt->cl_count, 1);
 133         clnt->cl_parent = clnt;
 134
 135         clnt->cl_server = clnt->cl_inline_name;
 136         len = strlen(servname) + 1;
 137         if (len > sizeof(clnt->cl_inline_name)) {
 138                 char *buf = kmalloc(len, GFP_KERNEL);
 139                 if (buf != 0)
 140                         clnt->cl_server = buf;
 141                 else
 142                         len = sizeof(clnt->cl_inline_name);
 143         }
 144         strlcpy(clnt->cl_server, servname, len);
 145
 146         clnt->cl_xprt     = xprt;
 147         clnt->cl_procinfo = version->procs;
 148         clnt->cl_maxproc  = version->nrprocs;
 149         clnt->cl_protname = program->name;
 150         clnt->cl_prog     = program->number;
 151         clnt->cl_vers     = version->number;
 152         clnt->cl_stats    = program->stats;
 153         clnt->cl_metrics  = rpc_alloc_iostats(clnt);
 154
 155         if (!xprt_bound(clnt->cl_xprt))
 156                 clnt->cl_autobind = 1;
 157
 158         clnt->cl_rtt = &clnt->cl_rtt_default;
 159         rpc_init_rtt(&clnt->cl_rtt_default, xprt->timeout.to_initval);
 160
 161         err = rpc_setup_pipedir(clnt, program->pipe_dir_name);
 162         if (err < 0)
 163                 goto out_no_path;
 164
 165         auth = rpcauth_create(flavor, clnt);
 166         if (IS_ERR(auth)) {
 167                 printk(KERN_INFO "RPC: Couldn't create auth handle (flavor %u)\n",
 168                                 flavor);
 169                 err = PTR_ERR(auth);
 170                 goto out_no_auth;
 171         }
 172
 173         /* save the nodename */
 174         clnt->cl_nodelen = strlen(system_utsname.nodename);
 175         if (clnt->cl_nodelen > UNX_MAXNODENAME)
 176                 clnt->cl_nodelen = UNX_MAXNODENAME;
 177         memcpy(clnt->cl_nodename, system_utsname.nodename, clnt->cl_nodelen);
 178         return clnt;
 179
 180 out_no_auth:
 181         if (!IS_ERR(clnt->cl_dentry)) {
 182                 rpc_rmdir(clnt->cl_dentry);
 183                 rpc_put_mount();
 184         }
 185 out_no_path:
 186         if (clnt->cl_server != clnt->cl_inline_name)
 187                 kfree(clnt->cl_server);
 188         kfree(clnt);
 189 out_err:
 190         xprt_destroy(xprt);
 191 out_no_xprt:
 192         return ERR_PTR(err);
 193 }
 194
 195 /**
 196  * Create an RPC client
 197  * @xprt - pointer to xprt struct
 198  * @servname - name of server
 199  * @info - rpc_program
 200  * @version - rpc_program version
 201  * @authflavor - rpc_auth flavour to use
 202  *
 203  * Creates an RPC client structure, then pings the server in order to
 204  * determine if it is up, and if it supports this program and version.
 205  *
 206  * This function should never be called by asynchronous tasks such as
 207  * the portmapper.
 208  */
 209 struct rpc_clnt *rpc_create_client(struct rpc_xprt *xprt, char *servname,
 210                 struct rpc_program *info, u32 version, rpc_authflavor_t authflavor)
 211 {
 212         struct rpc_clnt *clnt;
 213         int err;
 214
 215         clnt = rpc_new_client(xprt, servname, info, version, authflavor);
 216         if (IS_ERR(clnt))
 217                 return clnt;
 218         err = rpc_ping(clnt, RPC_TASK_SOFT|RPC_TASK_NOINTR);
 219         if (err == 0)
 220                 return clnt;
 221         rpc_shutdown_client(clnt);
 222         return ERR_PTR(err);
 223 }
 224
 225 /*
 226  * This function clones the RPC client structure. It allows us to share the
 227  * same transport while varying parameters such as the authentication
 228  * flavour.
 229  */
 230 struct rpc_clnt *
 231 rpc_clone_client(struct rpc_clnt *clnt)
 232 {
 233         struct rpc_clnt *new;
 234
 235         new = kmalloc(sizeof(*new), GFP_KERNEL);
 236         if (!new)
 237                 goto out_no_clnt;
 238         memcpy(new, clnt, sizeof(*new));
 239         atomic_set(&new->cl_count, 1);
 240         atomic_set(&new->cl_users, 0);
 241         new->cl_parent = clnt;
 242         atomic_inc(&clnt->cl_count);
 243         /* Turn off autobind on clones */
 244         new->cl_autobind = 0;
 245         new->cl_oneshot = 0;
 246         new->cl_dead = 0;
 247         if (!IS_ERR(new->cl_dentry))
 248                 dget(new->cl_dentry);
 249         rpc_init_rtt(&new->cl_rtt_default, clnt->cl_xprt->timeout.to_initval);
 250         if (new->cl_auth)
 251                 atomic_inc(&new->cl_auth->au_count);
 252         new->cl_metrics = rpc_alloc_iostats(clnt);
 253         return new;
 254 out_no_clnt:
 255         printk(KERN_INFO "RPC: out of memory in %s\n", __FUNCTION__);
 256         return ERR_PTR(-ENOMEM);
 257 }
 258
 259 /*
 260  * Properly shut down an RPC client, terminating all outstanding
 261  * requests. Note that we must be certain that cl_oneshot and
 262  * cl_dead are cleared, or else the client would be destroyed
 263  * when the last task releases it.
 264  */
 265 int
 266 rpc_shutdown_client(struct rpc_clnt *clnt)
 267 {
 268         dprintk("RPC: shutting down %s client for %s, tasks=%d\n",
 269                         clnt->cl_protname, clnt->cl_server,
 270                         atomic_read(&clnt->cl_users));
 271
 272         while (atomic_read(&clnt->cl_users) > 0) {
 273                 /* Don't let rpc_release_client destroy us */
 274                 clnt->cl_oneshot = 0;
 275                 clnt->cl_dead = 0;
 276                 rpc_killall_tasks(clnt);
 277                 wait_event_timeout(destroy_wait,
 278                         !atomic_read(&clnt->cl_users), 1*HZ);
 279         }
 280
 281         if (atomic_read(&clnt->cl_users) < 0) {
 282                 printk(KERN_ERR "RPC: rpc_shutdown_client clnt %p tasks=%d\n",
 283                                 clnt, atomic_read(&clnt->cl_users));
 284 #ifdef RPC_DEBUG
 285                 rpc_show_tasks();
 286 #endif
 287                 BUG();
 288         }
 289
 290         return rpc_destroy_client(clnt);
 291 }
 292
 293 /*
 294  * Delete an RPC client
 295  */
 296 int
 297 rpc_destroy_client(struct rpc_clnt *clnt)
 298 {
 299         if (!atomic_dec_and_test(&clnt->cl_count))
 300                 return 1;
 301         BUG_ON(atomic_read(&clnt->cl_users) != 0);
 302
 303         dprintk("RPC: destroying %s client for %s\n",
 304                         clnt->cl_protname, clnt->cl_server);
 305         if (clnt->cl_auth) {
 306                 rpcauth_destroy(clnt->cl_auth);
 307                 clnt->cl_auth = NULL;
 308         }
 309         if (clnt->cl_parent != clnt) {
 310                 if (!IS_ERR(clnt->cl_dentry))
 311                         dput(clnt->cl_dentry);
 312                 rpc_destroy_client(clnt->cl_parent);
 313                 goto out_free;
 314         }
 315         if (!IS_ERR(clnt->cl_dentry)) {
 316                 rpc_rmdir(clnt->cl_dentry);
 317                 rpc_put_mount();
 318         }
 319         if (clnt->cl_xprt) {
 320                 xprt_destroy(clnt->cl_xprt);
 321                 clnt->cl_xprt = NULL;
 322         }
 323         if (clnt->cl_server != clnt->cl_inline_name)
 324                 kfree(clnt->cl_server);
 325 out_free:
 326         rpc_free_iostats(clnt->cl_metrics);
 327         clnt->cl_metrics = NULL;
 328         kfree(clnt);
 329         return 0;
 330 }
 331
 332 /*
 333  * Release an RPC client
 334  */
 335 void
 336 rpc_release_client(struct rpc_clnt *clnt)
 337 {
 338         dprintk("RPC:      rpc_release_client(%p, %d)\n",
 339                                 clnt, atomic_read(&clnt->cl_users));
 340
 341         if (!atomic_dec_and_test(&clnt->cl_users))
 342                 return;
 343         wake_up(&destroy_wait);
 344         if (clnt->cl_oneshot || clnt->cl_dead)
 345                 rpc_destroy_client(clnt);
 346 }
 347
 348 /**
 349  * rpc_bind_new_program - bind a new RPC program to an existing client
 350  * @old - old rpc_client
 351  * @program - rpc program to set
 352  * @vers - rpc program version
 353  *
 354  * Clones the rpc client and sets up a new RPC program. This is mainly
 355  * of use for enabling different RPC programs to share the same transport.
 356  * The Sun NFSv2/v3 ACL protocol can do this.
 357  */
 358 struct rpc_clnt *rpc_bind_new_program(struct rpc_clnt *old,
 359                                       struct rpc_program *program,
 360                                       int vers)
 361 {
 362         struct rpc_clnt *clnt;
 363         struct rpc_version *version;
 364         int err;
 365
 366         BUG_ON(vers >= program->nrvers || !program->version[vers]);
 367         version = program->version[vers];
 368         clnt = rpc_clone_client(old);
 369         if (IS_ERR(clnt))
 370                 goto out;
 371         clnt->cl_procinfo = version->procs;
 372         clnt->cl_maxproc  = version->nrprocs;
 373         clnt->cl_protname = program->name;
 374         clnt->cl_prog     = program->number;
 375         clnt->cl_vers     = version->number;
 376         clnt->cl_stats    = program->stats;
 377         err = rpc_ping(clnt, RPC_TASK_SOFT|RPC_TASK_NOINTR);
 378         if (err != 0) {
 379                 rpc_shutdown_client(clnt);
 380                 clnt = ERR_PTR(err);
 381         }
 382 out:
 383         return clnt;
 384 }
 385
 386 /*
 387  * Default callback for async RPC calls
 388  */
 389 static void
 390 rpc_default_callback(struct rpc_task *task, void *data)
 391 {
 392 }
 393
 394 static const struct rpc_call_ops rpc_default_ops = {
 395         .rpc_call_done = rpc_default_callback,
 396 };
 397
 398 /*
 399  *      Export the signal mask handling for synchronous code that
 400  *      sleeps on RPC calls
 401  */
 402 #define RPC_INTR_SIGNALS (sigmask(SIGHUP) | sigmask(SIGINT) | sigmask(SIGQUIT) | sigmask(SIGTERM))
 403
 404 static void rpc_save_sigmask(sigset_t *oldset, int intr)
 405 {
 406         unsigned long   sigallow = sigmask(SIGKILL);
 407         sigset_t sigmask;
 408
 409         /* Block all signals except those listed in sigallow */
 410         if (intr)
 411                 sigallow |= RPC_INTR_SIGNALS;
 412         siginitsetinv(&sigmask, sigallow);
 413         sigprocmask(SIG_BLOCK, &sigmask, oldset);
 414 }
 415
 416 static inline void rpc_task_sigmask(struct rpc_task *task, sigset_t *oldset)
 417 {
 418         rpc_save_sigmask(oldset, !RPC_TASK_UNINTERRUPTIBLE(task));
 419 }
 420
 421 static inline void rpc_restore_sigmask(sigset_t *oldset)
 422 {
 423         sigprocmask(SIG_SETMASK, oldset, NULL);
 424 }
 425
 426 void rpc_clnt_sigmask(struct rpc_clnt *clnt, sigset_t *oldset)
 427 {
 428         rpc_save_sigmask(oldset, clnt->cl_intr);
 429 }
 430
 431 void rpc_clnt_sigunmask(struct rpc_clnt *clnt, sigset_t *oldset)
 432 {
 433         rpc_restore_sigmask(oldset);
 434 }
 435
 436 /*
 437  * New rpc_call implementation
 438  */
 439 int rpc_call_sync(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
 440 {
 441         struct rpc_task *task;
 442         sigset_t        oldset;
 443         int             status;
 444
 445         /* If this client is slain all further I/O fails */
 446         if (clnt->cl_dead)
 447                 return -EIO;
 448
 449         BUG_ON(flags & RPC_TASK_ASYNC);
 450
 451         status = -ENOMEM;
 452         task = rpc_new_task(clnt, flags, &rpc_default_ops, NULL);
 453         if (task == NULL)
 454                 goto out;
 455
 456         /* Mask signals on RPC calls _and_ GSS_AUTH upcalls */
 457         rpc_task_sigmask(task, &oldset);
 458
 459         rpc_call_setup(task, msg, 0);
 460
 461         /* Set up the call info struct and execute the task */
 462         status = task->tk_status;
 463         if (status == 0) {
 464                 atomic_inc(&task->tk_count);
 465                 status = rpc_execute(task);
 466                 if (status == 0)
 467                         status = task->tk_status;
 468         }
 469         rpc_restore_sigmask(&oldset);
 470         rpc_release_task(task);
 471 out:
 472         return status;
 473 }
 474
 475 /*
 476  * New rpc_call implementation
 477  */
 478 int
 479 rpc_call_async(struct rpc_clnt *clnt, struct rpc_message *msg, int flags,
 480                const struct rpc_call_ops *tk_ops, void *data)
 481 {
 482         struct rpc_task *task;
 483         sigset_t        oldset;
 484         int             status;
 485
 486         /* If this client is slain all further I/O fails */
 487         status = -EIO;
 488         if (clnt->cl_dead)
 489                 goto out_release;
 490
 491         flags |= RPC_TASK_ASYNC;
 492
 493         /* Create/initialize a new RPC task */
 494         status = -ENOMEM;
 495         if (!(task = rpc_new_task(clnt, flags, tk_ops, data)))
 496                 goto out_release;
 497
 498         /* Mask signals on GSS_AUTH upcalls */
 499         rpc_task_sigmask(task, &oldset);
 500
 501         rpc_call_setup(task, msg, 0);
 502
 503         /* Set up the call info struct and execute the task */
 504         status = task->tk_status;
 505         if (status == 0)
 506                 rpc_execute(task);
 507         else
 508                 rpc_release_task(task);
 509
 510         rpc_restore_sigmask(&oldset);
 511         return status;
 512 out_release:
 513         if (tk_ops->rpc_release != NULL)
 514                 tk_ops->rpc_release(data);
 515         return status;
 516 }
 517
 518
 519 void
 520 rpc_call_setup(struct rpc_task *task, struct rpc_message *msg, int flags)
 521 {
 522         task->tk_msg   = *msg;
 523         task->tk_flags |= flags;
 524         /* Bind the user cred */
 525         if (task->tk_msg.rpc_cred != NULL)
 526                 rpcauth_holdcred(task);
 527         else
 528                 rpcauth_bindcred(task);
 529
 530         if (task->tk_status == 0)
 531                 task->tk_action = call_start;
 532         else
 533                 task->tk_action = rpc_exit_task;
 534 }
 535
 536 void
 537 rpc_setbufsize(struct rpc_clnt *clnt, unsigned int sndsize, unsigned int rcvsize)
 538 {
 539         struct rpc_xprt *xprt = clnt->cl_xprt;
 540         if (xprt->ops->set_buffer_size)
 541                 xprt->ops->set_buffer_size(xprt, sndsize, rcvsize);
 542 }
 543
 544 /*
 545  * Return size of largest payload RPC client can support, in bytes
 546  *
 547  * For stream transports, this is one RPC record fragment (see RFC
 548  * 1831), as we don't support multi-record requests yet.  For datagram
 549  * transports, this is the size of an IP packet minus the IP, UDP, and
 550  * RPC header sizes.
 551  */
 552 size_t rpc_max_payload(struct rpc_clnt *clnt)
 553 {
 554         return clnt->cl_xprt->max_payload;
 555 }
 556 EXPORT_SYMBOL(rpc_max_payload);
 557
 558 /**
 559  * rpc_force_rebind - force transport to check that remote port is unchanged
 560  * @clnt: client to rebind
 561  *
 562  */
 563 void rpc_force_rebind(struct rpc_clnt *clnt)
 564 {
 565         if (clnt->cl_autobind)
 566                 xprt_clear_bound(clnt->cl_xprt);
 567 }
 568 EXPORT_SYMBOL(rpc_force_rebind);
 569
 570 /*
 571  * Restart an (async) RPC call. Usually called from within the
 572  * exit handler.
 573  */
 574 void
 575 rpc_restart_call(struct rpc_task *task)
 576 {
 577         if (RPC_ASSASSINATED(task))
 578                 return;
 579
 580         task->tk_action = call_start;
 581 }
 582
 583 /*
 584  * 0.  Initial state
 585  *
 586  *     Other FSM states can be visited zero or more times, but
 587  *     this state is visited exactly once for each RPC.
 588  */
 589 static void
 590 call_start(struct rpc_task *task)
 591 {
 592         struct rpc_clnt *clnt = task->tk_client;
 593
 594         dprintk("RPC: %4d call_start %s%d proc %d (%s)\n", task->tk_pid,
 595                 clnt->cl_protname, clnt->cl_vers, task->tk_msg.rpc_proc->p_proc,
 596                 (RPC_IS_ASYNC(task) ? "async" : "sync"));
 597
 598         /* Increment call count */
 599         task->tk_msg.rpc_proc->p_count++;
 600         clnt->cl_stats->rpccnt++;
 601         task->tk_action = call_reserve;
 602 }
 603
 604 /*
 605  * 1.   Reserve an RPC call slot
 606  */
 607 static void
 608 call_reserve(struct rpc_task *task)
 609 {
 610         dprintk("RPC: %4d call_reserve\n", task->tk_pid);
 611
 612         if (!rpcauth_uptodatecred(task)) {
 613                 task->tk_action = call_refresh;
 614                 return;
 615         }
 616
 617         task->tk_status  = 0;
 618         task->tk_action  = call_reserveresult;
 619         xprt_reserve(task);
 620 }
 621
 622 /*
 623  * 1b.  Grok the result of xprt_reserve()
 624  */
 625 static void
 626 call_reserveresult(struct rpc_task *task)
 627 {
 628         int status = task->tk_status;
 629
 630         dprintk("RPC: %4d call_reserveresult (status %d)\n",
 631                                 task->tk_pid, task->tk_status);
 632
 633         /*
 634          * After a call to xprt_reserve(), we must have either
 635          * a request slot or else an error status.
 636          */
 637         task->tk_status = 0;
 638         if (status >= 0) {
 639                 if (task->tk_rqstp) {
 640                         task->tk_action = call_allocate;
 641                         return;
 642                 }
 643
 644                 printk(KERN_ERR "%s: status=%d, but no request slot, exiting\n",
 645                                 __FUNCTION__, status);
 646                 rpc_exit(task, -EIO);
 647                 return;
 648         }
 649
 650         /*
 651          * Even though there was an error, we may have acquired
 652          * a request slot somehow.  Make sure not to leak it.
 653          */
 654         if (task->tk_rqstp) {
 655                 printk(KERN_ERR "%s: status=%d, request allocated anyway\n",
 656                                 __FUNCTION__, status);
 657                 xprt_release(task);
 658         }
 659
 660         switch (status) {
 661         case -EAGAIN:   /* woken up; retry */
 662                 task->tk_action = call_reserve;
 663                 return;
 664         case -EIO:      /* probably a shutdown */
 665                 break;
 666         default:
 667                 printk(KERN_ERR "%s: unrecognized error %d, exiting\n",
 668                                 __FUNCTION__, status);
 669                 break;
 670         }
 671         rpc_exit(task, status);
 672 }
 673
 674 /*
 675  * 2.   Allocate the buffer. For details, see sched.c:rpc_malloc.
 676  *      (Note: buffer memory is freed in xprt_release).
 677  */
 678 static void
 679 call_allocate(struct rpc_task *task)
 680 {
 681         struct rpc_rqst *req = task->tk_rqstp;
 682         struct rpc_xprt *xprt = task->tk_xprt;
 683         unsigned int    bufsiz;
 684
 685         dprintk("RPC: %4d call_allocate (status %d)\n",
 686                                 task->tk_pid, task->tk_status);
 687         task->tk_action = call_bind;
 688         if (req->rq_buffer)
 689                 return;
 690
 691         /* FIXME: compute buffer requirements more exactly using
 692          * auth->au_wslack */
 693         bufsiz = task->tk_msg.rpc_proc->p_bufsiz + RPC_SLACK_SPACE;
 694
 695         if (xprt->ops->buf_alloc(task, bufsiz << 1) != NULL)
 696                 return;
 697         printk(KERN_INFO "RPC: buffer allocation failed for task %p\n", task);
 698
 699         if (RPC_IS_ASYNC(task) || !signalled()) {
 700                 xprt_release(task);
 701                 task->tk_action = call_reserve;
 702                 rpc_delay(task, HZ>>4);
 703                 return;
 704         }
 705
 706         rpc_exit(task, -ERESTARTSYS);
 707 }
 708
 709 static inline int
 710 rpc_task_need_encode(struct rpc_task *task)
 711 {
 712         return task->tk_rqstp->rq_snd_buf.len == 0;
 713 }
 714
 715 static inline void
 716 rpc_task_force_reencode(struct rpc_task *task)
 717 {
 718         task->tk_rqstp->rq_snd_buf.len = 0;
 719 }
 720
 721 /*
 722  * 3.   Encode arguments of an RPC call
 723  */
 724 static void
 725 call_encode(struct rpc_task *task)
 726 {
 727         struct rpc_rqst *req = task->tk_rqstp;
 728         struct xdr_buf *sndbuf = &req->rq_snd_buf;
 729         struct xdr_buf *rcvbuf = &req->rq_rcv_buf;
 730         unsigned int    bufsiz;
 731         kxdrproc_t      encode;
 732         u32             *p;
 733
 734         dprintk("RPC: %4d call_encode (status %d)\n",
 735                                 task->tk_pid, task->tk_status);
 736
 737         /* Default buffer setup */
 738         bufsiz = req->rq_bufsize >> 1;
 739         sndbuf->head[0].iov_base = (void *)req->rq_buffer;
 740         sndbuf->head[0].iov_len  = bufsiz;
 741         sndbuf->tail[0].iov_len  = 0;
 742         sndbuf->page_len         = 0;
 743         sndbuf->len              = 0;
 744         sndbuf->buflen           = bufsiz;
 745         rcvbuf->head[0].iov_base = (void *)((char *)req->rq_buffer + bufsiz);
 746         rcvbuf->head[0].iov_len  = bufsiz;
 747         rcvbuf->tail[0].iov_len  = 0;
 748         rcvbuf->page_len         = 0;
 749         rcvbuf->len              = 0;
 750         rcvbuf->buflen           = bufsiz;
 751
 752         /* Encode header and provided arguments */
 753         encode = task->tk_msg.rpc_proc->p_encode;
 754         if (!(p = call_header(task))) {
 755                 printk(KERN_INFO "RPC: call_header failed, exit EIO\n");
 756                 rpc_exit(task, -EIO);
 757                 return;
 758         }
 759         if (encode == NULL)
 760                 return;
 761
 762         task->tk_status = rpcauth_wrap_req(task, encode, req, p,
 763                         task->tk_msg.rpc_argp);
 764         if (task->tk_status == -ENOMEM) {
 765                 /* XXX: Is this sane? */
 766                 rpc_delay(task, 3*HZ);
 767                 task->tk_status = -EAGAIN;
 768         }
 769 }
 770
 771 /*
 772  * 4.   Get the server port number if not yet set
 773  */
 774 static void
 775 call_bind(struct rpc_task *task)
 776 {
 777         struct rpc_clnt *clnt = task->tk_client;
 778         struct rpc_xprt *xprt = task->tk_xprt;
 779
 780         dprintk("RPC: %4d call_bind (status %d)\n",
 781                                 task->tk_pid, task->tk_status);
 782
 783         task->tk_action = call_connect;
 784         if (!xprt_bound(xprt)) {
 785                 task->tk_action = call_bind_status;
 786                 task->tk_timeout = xprt->bind_timeout;
 787                 rpc_getport(task, clnt);
 788         }
 789 }
 790
 791 /*
 792  * 4a.  Sort out bind result
 793  */
 794 static void
 795 call_bind_status(struct rpc_task *task)
 796 {
 797         int status = -EACCES;
 798
 799         if (task->tk_status >= 0) {
 800                 dprintk("RPC: %4d call_bind_status (status %d)\n",
 801                                         task->tk_pid, task->tk_status);
 802                 task->tk_status = 0;
 803                 task->tk_action = call_connect;
 804                 return;
 805         }
 806
 807         switch (task->tk_status) {
 808         case -EACCES:
 809                 dprintk("RPC: %4d remote rpcbind: RPC program/version unavailable\n",
 810                                 task->tk_pid);
 811                 rpc_delay(task, 3*HZ);
 812                 goto retry_bind;
 813         case -ETIMEDOUT:
 814                 dprintk("RPC: %4d rpcbind request timed out\n",
 815                                 task->tk_pid);
 816                 if (RPC_IS_SOFT(task)) {
 817                         status = -EIO;
 818                         break;
 819                 }
 820                 goto retry_bind;
 821         case -EPFNOSUPPORT:
 822                 dprintk("RPC: %4d remote rpcbind service unavailable\n",
 823                                 task->tk_pid);
 824                 break;
 825         case -EPROTONOSUPPORT:
 826                 dprintk("RPC: %4d remote rpcbind version 2 unavailable\n",
 827                                 task->tk_pid);
 828                 break;
 829         default:
 830                 dprintk("RPC: %4d unrecognized rpcbind error (%d)\n",
 831                                 task->tk_pid, -task->tk_status);
 832                 status = -EIO;
 833                 break;
 834         }
 835
 836         rpc_exit(task, status);
 837         return;
 838
 839 retry_bind:
 840         task->tk_status = 0;
 841         task->tk_action = call_bind;
 842         return;
 843 }
 844
 845 /*
 846  * 4b.  Connect to the RPC server
 847  */
 848 static void
 849 call_connect(struct rpc_task *task)
 850 {
 851         struct rpc_xprt *xprt = task->tk_xprt;
 852
 853         dprintk("RPC: %4d call_connect xprt %p %s connected\n",
 854                         task->tk_pid, xprt,
 855                         (xprt_connected(xprt) ? "is" : "is not"));
 856
 857         task->tk_action = call_transmit;
 858         if (!xprt_connected(xprt)) {
 859                 task->tk_action = call_connect_status;
 860                 if (task->tk_status < 0)
 861                         return;
 862                 xprt_connect(task);
 863         }
 864 }
 865
 866 /*
 867  * 4c.  Sort out connect result
 868  */
 869 static void
 870 call_connect_status(struct rpc_task *task)
 871 {
 872         struct rpc_clnt *clnt = task->tk_client;
 873         int status = task->tk_status;
 874
 875         dprintk("RPC: %5u call_connect_status (status %d)\n",
 876                                 task->tk_pid, task->tk_status);
 877
 878         task->tk_status = 0;
 879         if (status >= 0) {
 880                 clnt->cl_stats->netreconn++;
 881                 task->tk_action = call_transmit;
 882                 return;
 883         }
 884
 885         /* Something failed: remote service port may have changed */
 886         rpc_force_rebind(clnt);
 887
 888         switch (status) {
 889         case -ENOTCONN:
 890         case -ETIMEDOUT:
 891         case -EAGAIN:
 892                 task->tk_action = call_bind;
 893                 break;
 894         default:
 895                 rpc_exit(task, -EIO);
 896                 break;
 897         }
 898 }
 899
 900 /*
 901  * 5.   Transmit the RPC request, and wait for reply
 902  */
 903 static void
 904 call_transmit(struct rpc_task *task)
 905 {
 906         dprintk("RPC: %4d call_transmit (status %d)\n",
 907                                 task->tk_pid, task->tk_status);
 908
 909         task->tk_action = call_status;
 910         if (task->tk_status < 0)
 911                 return;
 912         task->tk_status = xprt_prepare_transmit(task);
 913         if (task->tk_status != 0)
 914                 return;
 915         task->tk_action = call_transmit_status;
 916         /* Encode here so that rpcsec_gss can use correct sequence number. */
 917         if (rpc_task_need_encode(task)) {
 918                 BUG_ON(task->tk_rqstp->rq_bytes_sent != 0);
 919                 call_encode(task);
 920                 /* Did the encode result in an error condition? */
 921                 if (task->tk_status != 0)
 922                         return;
 923         }
 924         xprt_transmit(task);
 925         if (task->tk_status < 0)
 926                 return;
 927         /*
 928          * On success, ensure that we call xprt_end_transmit() before sleeping
 929          * in order to allow access to the socket to other RPC requests.
 930          */
 931         call_transmit_status(task);
 932         if (task->tk_msg.rpc_proc->p_decode != NULL)
 933                 return;
 934         task->tk_action = rpc_exit_task;
 935         rpc_wake_up_task(task);
 936 }
 937
 938 /*
 939  * 5a.  Handle cleanup after a transmission
 940  */
 941 static void
 942 call_transmit_status(struct rpc_task *task)
 943 {
 944         task->tk_action = call_status;
 945         /*
 946          * Special case: if we've been waiting on the socket's write_space()
 947          * callback, then don't call xprt_end_transmit().
 948          */
 949         if (task->tk_status == -EAGAIN)
 950                 return;
 951         xprt_end_transmit(task);
 952         rpc_task_force_reencode(task);
 953 }
 954
 955 /*
 956  * 6.   Sort out the RPC call status
 957  */
 958 static void
 959 call_status(struct rpc_task *task)
 960 {
 961         struct rpc_clnt *clnt = task->tk_client;
 962         struct rpc_rqst *req = task->tk_rqstp;
 963         int             status;
 964
 965         if (req->rq_received > 0 && !req->rq_bytes_sent)
 966                 task->tk_status = req->rq_received;
 967
 968         dprintk("RPC: %4d call_status (status %d)\n",
 969                                 task->tk_pid, task->tk_status);
 970
 971         status = task->tk_status;
 972         if (status >= 0) {
 973                 task->tk_action = call_decode;
 974                 return;
 975         }
 976
 977         task->tk_status = 0;
 978         switch(status) {
 979         case -ETIMEDOUT:
 980                 task->tk_action = call_timeout;
 981                 break;
 982         case -ECONNREFUSED:
 983         case -ENOTCONN:
 984                 rpc_force_rebind(clnt);
 985                 task->tk_action = call_bind;
 986                 break;
 987         case -EAGAIN:
 988                 task->tk_action = call_transmit;
 989                 break;
 990         case -EIO:
 991                 /* shutdown or soft timeout */
 992                 rpc_exit(task, status);
 993                 break;
 994         default:
 995                 printk("%s: RPC call returned error %d\n",
 996                                clnt->cl_protname, -status);
 997                 rpc_exit(task, status);
 998                 break;
 999         }
1000 }
1001
1002 /*
1003  * 6a.  Handle RPC timeout
1004  *      We do not release the request slot, so we keep using the
1005  *      same XID for all retransmits.
1006  */
1007 static void
1008 call_timeout(struct rpc_task *task)
1009 {
1010         struct rpc_clnt *clnt = task->tk_client;
1011
1012         if (xprt_adjust_timeout(task->tk_rqstp) == 0) {
1013                 dprintk("RPC: %4d call_timeout (minor)\n", task->tk_pid);
1014                 goto retry;
1015         }
1016
1017         dprintk("RPC: %4d call_timeout (major)\n", task->tk_pid);
1018         task->tk_timeouts++;
1019
1020         if (RPC_IS_SOFT(task)) {
1021                 printk(KERN_NOTICE "%s: server %s not responding, timed out\n",
1022                                 clnt->cl_protname, clnt->cl_server);
1023                 rpc_exit(task, -EIO);
1024                 return;
1025         }
1026
1027         if (!(task->tk_flags & RPC_CALL_MAJORSEEN)) {
1028                 task->tk_flags |= RPC_CALL_MAJORSEEN;
1029                 printk(KERN_NOTICE "%s: server %s not responding, still trying\n",
1030                         clnt->cl_protname, clnt->cl_server);
1031         }
1032         rpc_force_rebind(clnt);
1033
1034 retry:
1035         clnt->cl_stats->rpcretrans++;
1036         task->tk_action = call_bind;
1037         task->tk_status = 0;
1038 }
1039
1040 /*
1041  * 7.   Decode the RPC reply
1042  */
1043 static void
1044 call_decode(struct rpc_task *task)
1045 {
1046         struct rpc_clnt *clnt = task->tk_client;
1047         struct rpc_rqst *req = task->tk_rqstp;
1048         kxdrproc_t      decode = task->tk_msg.rpc_proc->p_decode;
1049         u32             *p;
1050
1051         dprintk("RPC: %4d call_decode (status %d)\n",
1052                                 task->tk_pid, task->tk_status);
1053
1054         if (task->tk_flags & RPC_CALL_MAJORSEEN) {
1055                 printk(KERN_NOTICE "%s: server %s OK\n",
1056                         clnt->cl_protname, clnt->cl_server);
1057                 task->tk_flags &= ~RPC_CALL_MAJORSEEN;
1058         }
1059
1060         if (task->tk_status < 12) {
1061                 if (!RPC_IS_SOFT(task)) {
1062                         task->tk_action = call_bind;
1063                         clnt->cl_stats->rpcretrans++;
1064                         goto out_retry;
1065                 }
1066                 printk(KERN_WARNING "%s: too small RPC reply size (%d bytes)\n",
1067                         clnt->cl_protname, task->tk_status);
1068                 rpc_exit(task, -EIO);
1069                 return;
1070         }
1071
1072         /*
1073          * Ensure that we see all writes made by xprt_complete_rqst()
1074          * before it changed req->rq_received.
1075          */
1076         smp_rmb();
1077         req->rq_rcv_buf.len = req->rq_private_buf.len;
1078
1079         /* Check that the softirq receive buffer is valid */
1080         WARN_ON(memcmp(&req->rq_rcv_buf, &req->rq_private_buf,
1081                                 sizeof(req->rq_rcv_buf)) != 0);
1082
1083         /* Verify the RPC header */
1084         p = call_verify(task);
1085         if (IS_ERR(p)) {
1086                 if (p == ERR_PTR(-EAGAIN))
1087                         goto out_retry;
1088                 return;
1089         }
1090
1091         task->tk_action = rpc_exit_task;
1092
1093         if (decode)
1094                 task->tk_status = rpcauth_unwrap_resp(task, decode, req, p,
1095                                                       task->tk_msg.rpc_resp);
1096         dprintk("RPC: %4d call_decode result %d\n", task->tk_pid,
1097                                         task->tk_status);
1098         return;
1099 out_retry:
1100         req->rq_received = req->rq_private_buf.len = 0;
1101         task->tk_status = 0;
1102 }
1103
1104 /*
1105  * 8.   Refresh the credentials if rejected by the server
1106  */
1107 static void
1108 call_refresh(struct rpc_task *task)
1109 {
1110         dprintk("RPC: %4d call_refresh\n", task->tk_pid);
1111
1112         xprt_release(task);     /* Must do to obtain new XID */
1113         task->tk_action = call_refreshresult;
1114         task->tk_status = 0;
1115         task->tk_client->cl_stats->rpcauthrefresh++;
1116         rpcauth_refreshcred(task);
1117 }
1118
1119 /*
1120  * 8a.  Process the results of a credential refresh
1121  */
1122 static void
1123 call_refreshresult(struct rpc_task *task)
1124 {
1125         int status = task->tk_status;
1126         dprintk("RPC: %4d call_refreshresult (status %d)\n",
1127                                 task->tk_pid, task->tk_status);
1128
1129         task->tk_status = 0;
1130         task->tk_action = call_reserve;
1131         if (status >= 0 && rpcauth_uptodatecred(task))
1132                 return;
1133         if (status == -EACCES) {
1134                 rpc_exit(task, -EACCES);
1135                 return;
1136         }
1137         task->tk_action = call_refresh;
1138         if (status != -ETIMEDOUT)
1139                 rpc_delay(task, 3*HZ);
1140         return;
1141 }
1142
1143 /*
1144  * Call header serialization
1145  */
1146 static u32 *
1147 call_header(struct rpc_task *task)
1148 {
1149         struct rpc_clnt *clnt = task->tk_client;
1150         struct rpc_rqst *req = task->tk_rqstp;
1151         u32             *p = req->rq_svec[0].iov_base;
1152
1153         /* FIXME: check buffer size? */
1154
1155         p = xprt_skip_transport_header(task->tk_xprt, p);
1156         *p++ = req->rq_xid;             /* XID */
1157         *p++ = htonl(RPC_CALL);         /* CALL */
1158         *p++ = htonl(RPC_VERSION);      /* RPC version */
1159         *p++ = htonl(clnt->cl_prog);    /* program number */
1160         *p++ = htonl(clnt->cl_vers);    /* program version */
1161         *p++ = htonl(task->tk_msg.rpc_proc->p_proc);    /* procedure */
1162         p = rpcauth_marshcred(task, p);
1163         req->rq_slen = xdr_adjust_iovec(&req->rq_svec[0], p);
1164         return p;
1165 }
1166
1167 /*
1168  * Reply header verification
1169  */
1170 static u32 *
1171 call_verify(struct rpc_task *task)
1172 {
1173         struct kvec *iov = &task->tk_rqstp->rq_rcv_buf.head[0];
1174         int len = task->tk_rqstp->rq_rcv_buf.len >> 2;
1175         u32     *p = iov->iov_base, n;
1176         int error = -EACCES;
1177
1178         if ((task->tk_rqstp->rq_rcv_buf.len & 3) != 0) {
1179                 /* RFC-1014 says that the representation of XDR data must be a
1180                  * multiple of four bytes
1181                  * - if it isn't pointer subtraction in the NFS client may give
1182                  *   undefined results
1183                  */
1184                 printk(KERN_WARNING
1185                        "call_verify: XDR representation not a multiple of"
1186                        " 4 bytes: 0x%x\n", task->tk_rqstp->rq_rcv_buf.len);
1187                 goto out_eio;
1188         }
1189         if ((len -= 3) < 0)
1190                 goto out_overflow;
1191         p += 1; /* skip XID */
1192
1193         if ((n = ntohl(*p++)) != RPC_REPLY) {
1194                 printk(KERN_WARNING "call_verify: not an RPC reply: %x\n", n);
1195                 goto out_garbage;
1196         }
1197         if ((n = ntohl(*p++)) != RPC_MSG_ACCEPTED) {
1198                 if (--len < 0)
1199                         goto out_overflow;
1200                 switch ((n = ntohl(*p++))) {
1201                         case RPC_AUTH_ERROR:
1202                                 break;
1203                         case RPC_MISMATCH:
1204                                 dprintk("%s: RPC call version mismatch!\n", __FUNCTION__);
1205                                 error = -EPROTONOSUPPORT;
1206                                 goto out_err;
1207                         default:
1208                                 dprintk("%s: RPC call rejected, unknown error: %x\n", __FUNCTION__, n);
1209                                 goto out_eio;
1210                 }
1211                 if (--len < 0)
1212                         goto out_overflow;
1213                 switch ((n = ntohl(*p++))) {
1214                 case RPC_AUTH_REJECTEDCRED:
1215                 case RPC_AUTH_REJECTEDVERF:
1216                 case RPCSEC_GSS_CREDPROBLEM:
1217                 case RPCSEC_GSS_CTXPROBLEM:
1218                         if (!task->tk_cred_retry)
1219                                 break;
1220                         task->tk_cred_retry--;
1221                         dprintk("RPC: %4d call_verify: retry stale creds\n",
1222                                                         task->tk_pid);
1223                         rpcauth_invalcred(task);
1224                         task->tk_action = call_refresh;
1225                         goto out_retry;
1226                 case RPC_AUTH_BADCRED:
1227                 case RPC_AUTH_BADVERF:
1228                         /* possibly garbled cred/verf? */
1229                         if (!task->tk_garb_retry)
1230                                 break;
1231                         task->tk_garb_retry--;
1232                         dprintk("RPC: %4d call_verify: retry garbled creds\n",
1233                                                         task->tk_pid);
1234                         task->tk_action = call_bind;
1235                         goto out_retry;
1236                 case RPC_AUTH_TOOWEAK:
1237                         printk(KERN_NOTICE "call_verify: server %s requires stronger "
1238                                "authentication.\n", task->tk_client->cl_server);
1239                         break;
1240                 default:
1241                         printk(KERN_WARNING "call_verify: unknown auth error: %x\n", n);
1242                         error = -EIO;
1243                 }
1244                 dprintk("RPC: %4d call_verify: call rejected %d\n",
1245                                                 task->tk_pid, n);
1246                 goto out_err;
1247         }
1248         if (!(p = rpcauth_checkverf(task, p))) {
1249                 printk(KERN_WARNING "call_verify: auth check failed\n");
1250                 goto out_garbage;               /* bad verifier, retry */
1251         }
1252         len = p - (u32 *)iov->iov_base - 1;
1253         if (len < 0)
1254                 goto out_overflow;
1255         switch ((n = ntohl(*p++))) {
1256         case RPC_SUCCESS:
1257                 return p;
1258         case RPC_PROG_UNAVAIL:
1259                 dprintk("RPC: call_verify: program %u is unsupported by server %s\n",
1260                                 (unsigned int)task->tk_client->cl_prog,
1261                                 task->tk_client->cl_server);
1262                 error = -EPFNOSUPPORT;
1263                 goto out_err;
1264         case RPC_PROG_MISMATCH:
1265                 dprintk("RPC: call_verify: program %u, version %u unsupported by server %s\n",
1266                                 (unsigned int)task->tk_client->cl_prog,
1267                                 (unsigned int)task->tk_client->cl_vers,
1268                                 task->tk_client->cl_server);
1269                 error = -EPROTONOSUPPORT;
1270                 goto out_err;
1271         case RPC_PROC_UNAVAIL:
1272                 dprintk("RPC: call_verify: proc %p unsupported by program %u, version %u on server %s\n",
1273                                 task->tk_msg.rpc_proc,
1274                                 task->tk_client->cl_prog,
1275                                 task->tk_client->cl_vers,
1276                                 task->tk_client->cl_server);
1277                 error = -EOPNOTSUPP;
1278                 goto out_err;
1279         case RPC_GARBAGE_ARGS:
1280                 dprintk("RPC: %4d %s: server saw garbage\n", task->tk_pid, __FUNCTION__);
1281                 break;                  /* retry */
1282         default:
1283                 printk(KERN_WARNING "call_verify: server accept status: %x\n", n);
1284                 /* Also retry */
1285         }
1286
1287 out_garbage:
1288         task->tk_client->cl_stats->rpcgarbage++;
1289         if (task->tk_garb_retry) {
1290                 task->tk_garb_retry--;
1291                 dprintk("RPC %s: retrying %4d\n", __FUNCTION__, task->tk_pid);
1292                 task->tk_action = call_bind;
1293 out_retry:
1294                 return ERR_PTR(-EAGAIN);
1295         }
1296         printk(KERN_WARNING "RPC %s: retry failed, exit EIO\n", __FUNCTION__);
1297 out_eio:
1298         error = -EIO;
1299 out_err:
1300         rpc_exit(task, error);
1301         return ERR_PTR(error);
1302 out_overflow:
1303         printk(KERN_WARNING "RPC %s: server reply was truncated.\n", __FUNCTION__);
1304         goto out_garbage;
1305 }
1306
1307 static int rpcproc_encode_null(void *rqstp, u32 *data, void *obj)
1308 {
1309         return 0;
1310 }
1311
1312 static int rpcproc_decode_null(void *rqstp, u32 *data, void *obj)
1313 {
1314         return 0;
1315 }
1316
1317 static struct rpc_procinfo rpcproc_null = {
1318         .p_encode = rpcproc_encode_null,
1319         .p_decode = rpcproc_decode_null,
1320 };
1321
1322 int rpc_ping(struct rpc_clnt *clnt, int flags)
1323 {
1324         struct rpc_message msg = {
1325                 .rpc_proc = &rpcproc_null,
1326         };
1327         int err;
1328         msg.rpc_cred = authnull_ops.lookup_cred(NULL, NULL, 0);
1329         err = rpc_call_sync(clnt, &msg, flags);
1330         put_rpccred(msg.rpc_cred);
1331         return err;
1332 }