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   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 __be32 * call_header(struct rpc_task *task);
  64 static __be32 * 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 static struct rpc_clnt * rpc_new_client(struct rpc_xprt *xprt, char *servname, struct rpc_program *program, u32 vers, rpc_authflavor_t flavor)
 101 {
 102         struct rpc_version      *version;
 103         struct rpc_clnt         *clnt = NULL;
 104         struct rpc_auth         *auth;
 105         int err;
 106         int len;
 107
 108         dprintk("RPC: creating %s client for %s (xprt %p)\n",
 109                 program->name, servname, xprt);
 110
 111         err = -EINVAL;
 112         if (!xprt)
 113                 goto out_no_xprt;
 114         if (vers >= program->nrvers || !(version = program->version[vers]))
 115                 goto out_err;
 116
 117         err = -ENOMEM;
 118         clnt = kzalloc(sizeof(*clnt), GFP_KERNEL);
 119         if (!clnt)
 120                 goto out_err;
 121         atomic_set(&clnt->cl_users, 0);
 122         atomic_set(&clnt->cl_count, 1);
 123         clnt->cl_parent = clnt;
 124
 125         clnt->cl_server = clnt->cl_inline_name;
 126         len = strlen(servname) + 1;
 127         if (len > sizeof(clnt->cl_inline_name)) {
 128                 char *buf = kmalloc(len, GFP_KERNEL);
 129                 if (buf != 0)
 130                         clnt->cl_server = buf;
 131                 else
 132                         len = sizeof(clnt->cl_inline_name);
 133         }
 134         strlcpy(clnt->cl_server, servname, len);
 135
 136         clnt->cl_xprt     = xprt;
 137         clnt->cl_procinfo = version->procs;
 138         clnt->cl_maxproc  = version->nrprocs;
 139         clnt->cl_protname = program->name;
 140         clnt->cl_prog     = program->number;
 141         clnt->cl_vers     = version->number;
 142         clnt->cl_stats    = program->stats;
 143         clnt->cl_metrics  = rpc_alloc_iostats(clnt);
 144         err = -ENOMEM;
 145         if (clnt->cl_metrics == NULL)
 146                 goto out_no_stats;
 147         clnt->cl_program  = program;
 148
 149         if (!xprt_bound(clnt->cl_xprt))
 150                 clnt->cl_autobind = 1;
 151
 152         clnt->cl_rtt = &clnt->cl_rtt_default;
 153         rpc_init_rtt(&clnt->cl_rtt_default, xprt->timeout.to_initval);
 154
 155         err = rpc_setup_pipedir(clnt, program->pipe_dir_name);
 156         if (err < 0)
 157                 goto out_no_path;
 158
 159         auth = rpcauth_create(flavor, clnt);
 160         if (IS_ERR(auth)) {
 161                 printk(KERN_INFO "RPC: Couldn't create auth handle (flavor %u)\n",
 162                                 flavor);
 163                 err = PTR_ERR(auth);
 164                 goto out_no_auth;
 165         }
 166
 167         /* save the nodename */
 168         clnt->cl_nodelen = strlen(utsname()->nodename);
 169         if (clnt->cl_nodelen > UNX_MAXNODENAME)
 170                 clnt->cl_nodelen = UNX_MAXNODENAME;
 171         memcpy(clnt->cl_nodename, utsname()->nodename, clnt->cl_nodelen);
 172         return clnt;
 173
 174 out_no_auth:
 175         if (!IS_ERR(clnt->cl_dentry)) {
 176                 rpc_rmdir(clnt->cl_dentry);
 177                 rpc_put_mount();
 178         }
 179 out_no_path:
 180         rpc_free_iostats(clnt->cl_metrics);
 181 out_no_stats:
 182         if (clnt->cl_server != clnt->cl_inline_name)
 183                 kfree(clnt->cl_server);
 184         kfree(clnt);
 185 out_err:
 186         xprt_put(xprt);
 187 out_no_xprt:
 188         return ERR_PTR(err);
 189 }
 190
 191 /*
 192  * rpc_create - create an RPC client and transport with one call
 193  * @args: rpc_clnt create argument structure
 194  *
 195  * Creates and initializes an RPC transport and an RPC client.
 196  *
 197  * It can ping the server in order to determine if it is up, and to see if
 198  * it supports this program and version.  RPC_CLNT_CREATE_NOPING disables
 199  * this behavior so asynchronous tasks can also use rpc_create.
 200  */
 201 struct rpc_clnt *rpc_create(struct rpc_create_args *args)
 202 {
 203         struct rpc_xprt *xprt;
 204         struct rpc_clnt *clnt;
 205
 206         xprt = xprt_create_transport(args->protocol, args->address,
 207                                         args->addrsize, args->timeout);
 208         if (IS_ERR(xprt))
 209                 return (struct rpc_clnt *)xprt;
 210
 211         /*
 212          * By default, kernel RPC client connects from a reserved port.
 213          * CAP_NET_BIND_SERVICE will not be set for unprivileged requesters,
 214          * but it is always enabled for rpciod, which handles the connect
 215          * operation.
 216          */
 217         xprt->resvport = 1;
 218         if (args->flags & RPC_CLNT_CREATE_NONPRIVPORT)
 219                 xprt->resvport = 0;
 220
 221         dprintk("RPC:       creating %s client for %s (xprt %p)\n",
 222                 args->program->name, args->servername, xprt);
 223
 224         clnt = rpc_new_client(xprt, args->servername, args->program,
 225                                 args->version, args->authflavor);
 226         if (IS_ERR(clnt))
 227                 return clnt;
 228
 229         if (!(args->flags & RPC_CLNT_CREATE_NOPING)) {
 230                 int err = rpc_ping(clnt, RPC_TASK_SOFT|RPC_TASK_NOINTR);
 231                 if (err != 0) {
 232                         rpc_shutdown_client(clnt);
 233                         return ERR_PTR(err);
 234                 }
 235         }
 236
 237         clnt->cl_softrtry = 1;
 238         if (args->flags & RPC_CLNT_CREATE_HARDRTRY)
 239                 clnt->cl_softrtry = 0;
 240
 241         if (args->flags & RPC_CLNT_CREATE_INTR)
 242                 clnt->cl_intr = 1;
 243         if (args->flags & RPC_CLNT_CREATE_AUTOBIND)
 244                 clnt->cl_autobind = 1;
 245         if (args->flags & RPC_CLNT_CREATE_ONESHOT)
 246                 clnt->cl_oneshot = 1;
 247
 248         return clnt;
 249 }
 250 EXPORT_SYMBOL_GPL(rpc_create);
 251
 252 /*
 253  * This function clones the RPC client structure. It allows us to share the
 254  * same transport while varying parameters such as the authentication
 255  * flavour.
 256  */
 257 struct rpc_clnt *
 258 rpc_clone_client(struct rpc_clnt *clnt)
 259 {
 260         struct rpc_clnt *new;
 261         int err = -ENOMEM;
 262
 263         new = kmemdup(clnt, sizeof(*new), GFP_KERNEL);
 264         if (!new)
 265                 goto out_no_clnt;
 266         atomic_set(&new->cl_count, 1);
 267         atomic_set(&new->cl_users, 0);
 268         new->cl_metrics = rpc_alloc_iostats(clnt);
 269         if (new->cl_metrics == NULL)
 270                 goto out_no_stats;
 271         err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name);
 272         if (err != 0)
 273                 goto out_no_path;
 274         new->cl_parent = clnt;
 275         atomic_inc(&clnt->cl_count);
 276         new->cl_xprt = xprt_get(clnt->cl_xprt);
 277         /* Turn off autobind on clones */
 278         new->cl_autobind = 0;
 279         new->cl_oneshot = 0;
 280         new->cl_dead = 0;
 281         rpc_init_rtt(&new->cl_rtt_default, clnt->cl_xprt->timeout.to_initval);
 282         if (new->cl_auth)
 283                 atomic_inc(&new->cl_auth->au_count);
 284         return new;
 285 out_no_path:
 286         rpc_free_iostats(new->cl_metrics);
 287 out_no_stats:
 288         kfree(new);
 289 out_no_clnt:
 290         dprintk("RPC: %s returned error %d\n", __FUNCTION__, err);
 291         return ERR_PTR(err);
 292 }
 293
 294 /*
 295  * Properly shut down an RPC client, terminating all outstanding
 296  * requests. Note that we must be certain that cl_oneshot and
 297  * cl_dead are cleared, or else the client would be destroyed
 298  * when the last task releases it.
 299  */
 300 int
 301 rpc_shutdown_client(struct rpc_clnt *clnt)
 302 {
 303         dprintk("RPC: shutting down %s client for %s, tasks=%d\n",
 304                         clnt->cl_protname, clnt->cl_server,
 305                         atomic_read(&clnt->cl_users));
 306
 307         while (atomic_read(&clnt->cl_users) > 0) {
 308                 /* Don't let rpc_release_client destroy us */
 309                 clnt->cl_oneshot = 0;
 310                 clnt->cl_dead = 0;
 311                 rpc_killall_tasks(clnt);
 312                 wait_event_timeout(destroy_wait,
 313                         !atomic_read(&clnt->cl_users), 1*HZ);
 314         }
 315
 316         if (atomic_read(&clnt->cl_users) < 0) {
 317                 printk(KERN_ERR "RPC: rpc_shutdown_client clnt %p tasks=%d\n",
 318                                 clnt, atomic_read(&clnt->cl_users));
 319 #ifdef RPC_DEBUG
 320                 rpc_show_tasks();
 321 #endif
 322                 BUG();
 323         }
 324
 325         return rpc_destroy_client(clnt);
 326 }
 327
 328 /*
 329  * Delete an RPC client
 330  */
 331 int
 332 rpc_destroy_client(struct rpc_clnt *clnt)
 333 {
 334         if (!atomic_dec_and_test(&clnt->cl_count))
 335                 return 1;
 336         BUG_ON(atomic_read(&clnt->cl_users) != 0);
 337
 338         dprintk("RPC: destroying %s client for %s\n",
 339                         clnt->cl_protname, clnt->cl_server);
 340         if (clnt->cl_auth) {
 341                 rpcauth_destroy(clnt->cl_auth);
 342                 clnt->cl_auth = NULL;
 343         }
 344         if (!IS_ERR(clnt->cl_dentry)) {
 345                 rpc_rmdir(clnt->cl_dentry);
 346                 rpc_put_mount();
 347         }
 348         if (clnt->cl_parent != clnt) {
 349                 rpc_destroy_client(clnt->cl_parent);
 350                 goto out_free;
 351         }
 352         if (clnt->cl_server != clnt->cl_inline_name)
 353                 kfree(clnt->cl_server);
 354 out_free:
 355         rpc_free_iostats(clnt->cl_metrics);
 356         clnt->cl_metrics = NULL;
 357         xprt_put(clnt->cl_xprt);
 358         kfree(clnt);
 359         return 0;
 360 }
 361
 362 /*
 363  * Release an RPC client
 364  */
 365 void
 366 rpc_release_client(struct rpc_clnt *clnt)
 367 {
 368         dprintk("RPC:      rpc_release_client(%p, %d)\n",
 369                                 clnt, atomic_read(&clnt->cl_users));
 370
 371         if (!atomic_dec_and_test(&clnt->cl_users))
 372                 return;
 373         wake_up(&destroy_wait);
 374         if (clnt->cl_oneshot || clnt->cl_dead)
 375                 rpc_destroy_client(clnt);
 376 }
 377
 378 /**
 379  * rpc_bind_new_program - bind a new RPC program to an existing client
 380  * @old - old rpc_client
 381  * @program - rpc program to set
 382  * @vers - rpc program version
 383  *
 384  * Clones the rpc client and sets up a new RPC program. This is mainly
 385  * of use for enabling different RPC programs to share the same transport.
 386  * The Sun NFSv2/v3 ACL protocol can do this.
 387  */
 388 struct rpc_clnt *rpc_bind_new_program(struct rpc_clnt *old,
 389                                       struct rpc_program *program,
 390                                       int vers)
 391 {
 392         struct rpc_clnt *clnt;
 393         struct rpc_version *version;
 394         int err;
 395
 396         BUG_ON(vers >= program->nrvers || !program->version[vers]);
 397         version = program->version[vers];
 398         clnt = rpc_clone_client(old);
 399         if (IS_ERR(clnt))
 400                 goto out;
 401         clnt->cl_procinfo = version->procs;
 402         clnt->cl_maxproc  = version->nrprocs;
 403         clnt->cl_protname = program->name;
 404         clnt->cl_prog     = program->number;
 405         clnt->cl_vers     = version->number;
 406         clnt->cl_stats    = program->stats;
 407         err = rpc_ping(clnt, RPC_TASK_SOFT|RPC_TASK_NOINTR);
 408         if (err != 0) {
 409                 rpc_shutdown_client(clnt);
 410                 clnt = ERR_PTR(err);
 411         }
 412 out:
 413         return clnt;
 414 }
 415
 416 /*
 417  * Default callback for async RPC calls
 418  */
 419 static void
 420 rpc_default_callback(struct rpc_task *task, void *data)
 421 {
 422 }
 423
 424 static const struct rpc_call_ops rpc_default_ops = {
 425         .rpc_call_done = rpc_default_callback,
 426 };
 427
 428 /*
 429  *      Export the signal mask handling for synchronous code that
 430  *      sleeps on RPC calls
 431  */
 432 #define RPC_INTR_SIGNALS (sigmask(SIGHUP) | sigmask(SIGINT) | sigmask(SIGQUIT) | sigmask(SIGTERM))
 433
 434 static void rpc_save_sigmask(sigset_t *oldset, int intr)
 435 {
 436         unsigned long   sigallow = sigmask(SIGKILL);
 437         sigset_t sigmask;
 438
 439         /* Block all signals except those listed in sigallow */
 440         if (intr)
 441                 sigallow |= RPC_INTR_SIGNALS;
 442         siginitsetinv(&sigmask, sigallow);
 443         sigprocmask(SIG_BLOCK, &sigmask, oldset);
 444 }
 445
 446 static inline void rpc_task_sigmask(struct rpc_task *task, sigset_t *oldset)
 447 {
 448         rpc_save_sigmask(oldset, !RPC_TASK_UNINTERRUPTIBLE(task));
 449 }
 450
 451 static inline void rpc_restore_sigmask(sigset_t *oldset)
 452 {
 453         sigprocmask(SIG_SETMASK, oldset, NULL);
 454 }
 455
 456 void rpc_clnt_sigmask(struct rpc_clnt *clnt, sigset_t *oldset)
 457 {
 458         rpc_save_sigmask(oldset, clnt->cl_intr);
 459 }
 460
 461 void rpc_clnt_sigunmask(struct rpc_clnt *clnt, sigset_t *oldset)
 462 {
 463         rpc_restore_sigmask(oldset);
 464 }
 465
 466 /*
 467  * New rpc_call implementation
 468  */
 469 int rpc_call_sync(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
 470 {
 471         struct rpc_task *task;
 472         sigset_t        oldset;
 473         int             status;
 474
 475         /* If this client is slain all further I/O fails */
 476         if (clnt->cl_dead)
 477                 return -EIO;
 478
 479         BUG_ON(flags & RPC_TASK_ASYNC);
 480
 481         task = rpc_new_task(clnt, flags, &rpc_default_ops, NULL);
 482         if (task == NULL)
 483                 return -ENOMEM;
 484
 485         /* Mask signals on RPC calls _and_ GSS_AUTH upcalls */
 486         rpc_task_sigmask(task, &oldset);
 487
 488         rpc_call_setup(task, msg, 0);
 489
 490         /* Set up the call info struct and execute the task */
 491         status = task->tk_status;
 492         if (status != 0) {
 493                 rpc_release_task(task);
 494                 goto out;
 495         }
 496         atomic_inc(&task->tk_count);
 497         status = rpc_execute(task);
 498         if (status == 0)
 499                 status = task->tk_status;
 500         rpc_put_task(task);
 501 out:
 502         rpc_restore_sigmask(&oldset);
 503         return status;
 504 }
 505
 506 /*
 507  * New rpc_call implementation
 508  */
 509 int
 510 rpc_call_async(struct rpc_clnt *clnt, struct rpc_message *msg, int flags,
 511                const struct rpc_call_ops *tk_ops, void *data)
 512 {
 513         struct rpc_task *task;
 514         sigset_t        oldset;
 515         int             status;
 516
 517         /* If this client is slain all further I/O fails */
 518         status = -EIO;
 519         if (clnt->cl_dead)
 520                 goto out_release;
 521
 522         flags |= RPC_TASK_ASYNC;
 523
 524         /* Create/initialize a new RPC task */
 525         status = -ENOMEM;
 526         if (!(task = rpc_new_task(clnt, flags, tk_ops, data)))
 527                 goto out_release;
 528
 529         /* Mask signals on GSS_AUTH upcalls */
 530         rpc_task_sigmask(task, &oldset);
 531
 532         rpc_call_setup(task, msg, 0);
 533
 534         /* Set up the call info struct and execute the task */
 535         status = task->tk_status;
 536         if (status == 0)
 537                 rpc_execute(task);
 538         else
 539                 rpc_release_task(task);
 540
 541         rpc_restore_sigmask(&oldset);
 542         return status;
 543 out_release:
 544         if (tk_ops->rpc_release != NULL)
 545                 tk_ops->rpc_release(data);
 546         return status;
 547 }
 548
 549
 550 void
 551 rpc_call_setup(struct rpc_task *task, struct rpc_message *msg, int flags)
 552 {
 553         task->tk_msg   = *msg;
 554         task->tk_flags |= flags;
 555         /* Bind the user cred */
 556         if (task->tk_msg.rpc_cred != NULL)
 557                 rpcauth_holdcred(task);
 558         else
 559                 rpcauth_bindcred(task);
 560
 561         if (task->tk_status == 0)
 562                 task->tk_action = call_start;
 563         else
 564                 task->tk_action = rpc_exit_task;
 565 }
 566
 567 /**
 568  * rpc_peeraddr - extract remote peer address from clnt's xprt
 569  * @clnt: RPC client structure
 570  * @buf: target buffer
 571  * @size: length of target buffer
 572  *
 573  * Returns the number of bytes that are actually in the stored address.
 574  */
 575 size_t rpc_peeraddr(struct rpc_clnt *clnt, struct sockaddr *buf, size_t bufsize)
 576 {
 577         size_t bytes;
 578         struct rpc_xprt *xprt = clnt->cl_xprt;
 579
 580         bytes = sizeof(xprt->addr);
 581         if (bytes > bufsize)
 582                 bytes = bufsize;
 583         memcpy(buf, &clnt->cl_xprt->addr, bytes);
 584         return xprt->addrlen;
 585 }
 586 EXPORT_SYMBOL_GPL(rpc_peeraddr);
 587
 588 /**
 589  * rpc_peeraddr2str - return remote peer address in printable format
 590  * @clnt: RPC client structure
 591  * @format: address format
 592  *
 593  */
 594 char *rpc_peeraddr2str(struct rpc_clnt *clnt, enum rpc_display_format_t format)
 595 {
 596         struct rpc_xprt *xprt = clnt->cl_xprt;
 597         return xprt->ops->print_addr(xprt, format);
 598 }
 599 EXPORT_SYMBOL_GPL(rpc_peeraddr2str);
 600
 601 void
 602 rpc_setbufsize(struct rpc_clnt *clnt, unsigned int sndsize, unsigned int rcvsize)
 603 {
 604         struct rpc_xprt *xprt = clnt->cl_xprt;
 605         if (xprt->ops->set_buffer_size)
 606                 xprt->ops->set_buffer_size(xprt, sndsize, rcvsize);
 607 }
 608
 609 /*
 610  * Return size of largest payload RPC client can support, in bytes
 611  *
 612  * For stream transports, this is one RPC record fragment (see RFC
 613  * 1831), as we don't support multi-record requests yet.  For datagram
 614  * transports, this is the size of an IP packet minus the IP, UDP, and
 615  * RPC header sizes.
 616  */
 617 size_t rpc_max_payload(struct rpc_clnt *clnt)
 618 {
 619         return clnt->cl_xprt->max_payload;
 620 }
 621 EXPORT_SYMBOL_GPL(rpc_max_payload);
 622
 623 /**
 624  * rpc_force_rebind - force transport to check that remote port is unchanged
 625  * @clnt: client to rebind
 626  *
 627  */
 628 void rpc_force_rebind(struct rpc_clnt *clnt)
 629 {
 630         if (clnt->cl_autobind)
 631                 xprt_clear_bound(clnt->cl_xprt);
 632 }
 633 EXPORT_SYMBOL_GPL(rpc_force_rebind);
 634
 635 /*
 636  * Restart an (async) RPC call. Usually called from within the
 637  * exit handler.
 638  */
 639 void
 640 rpc_restart_call(struct rpc_task *task)
 641 {
 642         if (RPC_ASSASSINATED(task))
 643                 return;
 644
 645         task->tk_action = call_start;
 646 }
 647
 648 /*
 649  * 0.  Initial state
 650  *
 651  *     Other FSM states can be visited zero or more times, but
 652  *     this state is visited exactly once for each RPC.
 653  */
 654 static void
 655 call_start(struct rpc_task *task)
 656 {
 657         struct rpc_clnt *clnt = task->tk_client;
 658
 659         dprintk("RPC: %4d call_start %s%d proc %d (%s)\n", task->tk_pid,
 660                 clnt->cl_protname, clnt->cl_vers, task->tk_msg.rpc_proc->p_proc,
 661                 (RPC_IS_ASYNC(task) ? "async" : "sync"));
 662
 663         /* Increment call count */
 664         task->tk_msg.rpc_proc->p_count++;
 665         clnt->cl_stats->rpccnt++;
 666         task->tk_action = call_reserve;
 667 }
 668
 669 /*
 670  * 1.   Reserve an RPC call slot
 671  */
 672 static void
 673 call_reserve(struct rpc_task *task)
 674 {
 675         dprintk("RPC: %4d call_reserve\n", task->tk_pid);
 676
 677         if (!rpcauth_uptodatecred(task)) {
 678                 task->tk_action = call_refresh;
 679                 return;
 680         }
 681
 682         task->tk_status  = 0;
 683         task->tk_action  = call_reserveresult;
 684         xprt_reserve(task);
 685 }
 686
 687 /*
 688  * 1b.  Grok the result of xprt_reserve()
 689  */
 690 static void
 691 call_reserveresult(struct rpc_task *task)
 692 {
 693         int status = task->tk_status;
 694
 695         dprintk("RPC: %4d call_reserveresult (status %d)\n",
 696                                 task->tk_pid, task->tk_status);
 697
 698         /*
 699          * After a call to xprt_reserve(), we must have either
 700          * a request slot or else an error status.
 701          */
 702         task->tk_status = 0;
 703         if (status >= 0) {
 704                 if (task->tk_rqstp) {
 705                         task->tk_action = call_allocate;
 706                         return;
 707                 }
 708
 709                 printk(KERN_ERR "%s: status=%d, but no request slot, exiting\n",
 710                                 __FUNCTION__, status);
 711                 rpc_exit(task, -EIO);
 712                 return;
 713         }
 714
 715         /*
 716          * Even though there was an error, we may have acquired
 717          * a request slot somehow.  Make sure not to leak it.
 718          */
 719         if (task->tk_rqstp) {
 720                 printk(KERN_ERR "%s: status=%d, request allocated anyway\n",
 721                                 __FUNCTION__, status);
 722                 xprt_release(task);
 723         }
 724
 725         switch (status) {
 726         case -EAGAIN:   /* woken up; retry */
 727                 task->tk_action = call_reserve;
 728                 return;
 729         case -EIO:      /* probably a shutdown */
 730                 break;
 731         default:
 732                 printk(KERN_ERR "%s: unrecognized error %d, exiting\n",
 733                                 __FUNCTION__, status);
 734                 break;
 735         }
 736         rpc_exit(task, status);
 737 }
 738
 739 /*
 740  * 2.   Allocate the buffer. For details, see sched.c:rpc_malloc.
 741  *      (Note: buffer memory is freed in xprt_release).
 742  */
 743 static void
 744 call_allocate(struct rpc_task *task)
 745 {
 746         struct rpc_rqst *req = task->tk_rqstp;
 747         struct rpc_xprt *xprt = task->tk_xprt;
 748         unsigned int    bufsiz;
 749
 750         dprintk("RPC: %4d call_allocate (status %d)\n",
 751                                 task->tk_pid, task->tk_status);
 752         task->tk_action = call_bind;
 753         if (req->rq_buffer)
 754                 return;
 755
 756         /* FIXME: compute buffer requirements more exactly using
 757          * auth->au_wslack */
 758         bufsiz = task->tk_msg.rpc_proc->p_bufsiz + RPC_SLACK_SPACE;
 759
 760         if (xprt->ops->buf_alloc(task, bufsiz << 1) != NULL)
 761                 return;
 762         printk(KERN_INFO "RPC: buffer allocation failed for task %p\n", task);
 763
 764         if (RPC_IS_ASYNC(task) || !signalled()) {
 765                 xprt_release(task);
 766                 task->tk_action = call_reserve;
 767                 rpc_delay(task, HZ>>4);
 768                 return;
 769         }
 770
 771         rpc_exit(task, -ERESTARTSYS);
 772 }
 773
 774 static inline int
 775 rpc_task_need_encode(struct rpc_task *task)
 776 {
 777         return task->tk_rqstp->rq_snd_buf.len == 0;
 778 }
 779
 780 static inline void
 781 rpc_task_force_reencode(struct rpc_task *task)
 782 {
 783         task->tk_rqstp->rq_snd_buf.len = 0;
 784 }
 785
 786 /*
 787  * 3.   Encode arguments of an RPC call
 788  */
 789 static void
 790 call_encode(struct rpc_task *task)
 791 {
 792         struct rpc_rqst *req = task->tk_rqstp;
 793         struct xdr_buf *sndbuf = &req->rq_snd_buf;
 794         struct xdr_buf *rcvbuf = &req->rq_rcv_buf;
 795         unsigned int    bufsiz;
 796         kxdrproc_t      encode;
 797         __be32          *p;
 798
 799         dprintk("RPC: %4d call_encode (status %d)\n",
 800                                 task->tk_pid, task->tk_status);
 801
 802         /* Default buffer setup */
 803         bufsiz = req->rq_bufsize >> 1;
 804         sndbuf->head[0].iov_base = (void *)req->rq_buffer;
 805         sndbuf->head[0].iov_len  = bufsiz;
 806         sndbuf->tail[0].iov_len  = 0;
 807         sndbuf->page_len         = 0;
 808         sndbuf->len              = 0;
 809         sndbuf->buflen           = bufsiz;
 810         rcvbuf->head[0].iov_base = (void *)((char *)req->rq_buffer + bufsiz);
 811         rcvbuf->head[0].iov_len  = bufsiz;
 812         rcvbuf->tail[0].iov_len  = 0;
 813         rcvbuf->page_len         = 0;
 814         rcvbuf->len              = 0;
 815         rcvbuf->buflen           = bufsiz;
 816
 817         /* Encode header and provided arguments */
 818         encode = task->tk_msg.rpc_proc->p_encode;
 819         if (!(p = call_header(task))) {
 820                 printk(KERN_INFO "RPC: call_header failed, exit EIO\n");
 821                 rpc_exit(task, -EIO);
 822                 return;
 823         }
 824         if (encode == NULL)
 825                 return;
 826
 827         task->tk_status = rpcauth_wrap_req(task, encode, req, p,
 828                         task->tk_msg.rpc_argp);
 829         if (task->tk_status == -ENOMEM) {
 830                 /* XXX: Is this sane? */
 831                 rpc_delay(task, 3*HZ);
 832                 task->tk_status = -EAGAIN;
 833         }
 834 }
 835
 836 /*
 837  * 4.   Get the server port number if not yet set
 838  */
 839 static void
 840 call_bind(struct rpc_task *task)
 841 {
 842         struct rpc_xprt *xprt = task->tk_xprt;
 843
 844         dprintk("RPC: %4d call_bind (status %d)\n",
 845                                 task->tk_pid, task->tk_status);
 846
 847         task->tk_action = call_connect;
 848         if (!xprt_bound(xprt)) {
 849                 task->tk_action = call_bind_status;
 850                 task->tk_timeout = xprt->bind_timeout;
 851                 xprt->ops->rpcbind(task);
 852         }
 853 }
 854
 855 /*
 856  * 4a.  Sort out bind result
 857  */
 858 static void
 859 call_bind_status(struct rpc_task *task)
 860 {
 861         int status = -EACCES;
 862
 863         if (task->tk_status >= 0) {
 864                 dprintk("RPC: %4d call_bind_status (status %d)\n",
 865                                         task->tk_pid, task->tk_status);
 866                 task->tk_status = 0;
 867                 task->tk_action = call_connect;
 868                 return;
 869         }
 870
 871         switch (task->tk_status) {
 872         case -EACCES:
 873                 dprintk("RPC: %4d remote rpcbind: RPC program/version unavailable\n",
 874                                 task->tk_pid);
 875                 rpc_delay(task, 3*HZ);
 876                 goto retry_timeout;
 877         case -ETIMEDOUT:
 878                 dprintk("RPC: %4d rpcbind request timed out\n",
 879                                 task->tk_pid);
 880                 goto retry_timeout;
 881         case -EPFNOSUPPORT:
 882                 dprintk("RPC: %4d remote rpcbind service unavailable\n",
 883                                 task->tk_pid);
 884                 break;
 885         case -EPROTONOSUPPORT:
 886                 dprintk("RPC: %4d remote rpcbind version 2 unavailable\n",
 887                                 task->tk_pid);
 888                 break;
 889         default:
 890                 dprintk("RPC: %4d unrecognized rpcbind error (%d)\n",
 891                                 task->tk_pid, -task->tk_status);
 892                 status = -EIO;
 893         }
 894
 895         rpc_exit(task, status);
 896         return;
 897
 898 retry_timeout:
 899         task->tk_action = call_timeout;
 900 }
 901
 902 /*
 903  * 4b.  Connect to the RPC server
 904  */
 905 static void
 906 call_connect(struct rpc_task *task)
 907 {
 908         struct rpc_xprt *xprt = task->tk_xprt;
 909
 910         dprintk("RPC: %4d call_connect xprt %p %s connected\n",
 911                         task->tk_pid, xprt,
 912                         (xprt_connected(xprt) ? "is" : "is not"));
 913
 914         task->tk_action = call_transmit;
 915         if (!xprt_connected(xprt)) {
 916                 task->tk_action = call_connect_status;
 917                 if (task->tk_status < 0)
 918                         return;
 919                 xprt_connect(task);
 920         }
 921 }
 922
 923 /*
 924  * 4c.  Sort out connect result
 925  */
 926 static void
 927 call_connect_status(struct rpc_task *task)
 928 {
 929         struct rpc_clnt *clnt = task->tk_client;
 930         int status = task->tk_status;
 931
 932         dprintk("RPC: %5u call_connect_status (status %d)\n",
 933                                 task->tk_pid, task->tk_status);
 934
 935         task->tk_status = 0;
 936         if (status >= 0) {
 937                 clnt->cl_stats->netreconn++;
 938                 task->tk_action = call_transmit;
 939                 return;
 940         }
 941
 942         /* Something failed: remote service port may have changed */
 943         rpc_force_rebind(clnt);
 944
 945         switch (status) {
 946         case -ENOTCONN:
 947         case -EAGAIN:
 948                 task->tk_action = call_bind;
 949                 if (!RPC_IS_SOFT(task))
 950                         return;
 951                 /* if soft mounted, test if we've timed out */
 952         case -ETIMEDOUT:
 953                 task->tk_action = call_timeout;
 954                 return;
 955         }
 956         rpc_exit(task, -EIO);
 957 }
 958
 959 /*
 960  * 5.   Transmit the RPC request, and wait for reply
 961  */
 962 static void
 963 call_transmit(struct rpc_task *task)
 964 {
 965         dprintk("RPC: %4d call_transmit (status %d)\n",
 966                                 task->tk_pid, task->tk_status);
 967
 968         task->tk_action = call_status;
 969         if (task->tk_status < 0)
 970                 return;
 971         task->tk_status = xprt_prepare_transmit(task);
 972         if (task->tk_status != 0)
 973                 return;
 974         task->tk_action = call_transmit_status;
 975         /* Encode here so that rpcsec_gss can use correct sequence number. */
 976         if (rpc_task_need_encode(task)) {
 977                 BUG_ON(task->tk_rqstp->rq_bytes_sent != 0);
 978                 call_encode(task);
 979                 /* Did the encode result in an error condition? */
 980                 if (task->tk_status != 0)
 981                         return;
 982         }
 983         xprt_transmit(task);
 984         if (task->tk_status < 0)
 985                 return;
 986         /*
 987          * On success, ensure that we call xprt_end_transmit() before sleeping
 988          * in order to allow access to the socket to other RPC requests.
 989          */
 990         call_transmit_status(task);
 991         if (task->tk_msg.rpc_proc->p_decode != NULL)
 992                 return;
 993         task->tk_action = rpc_exit_task;
 994         rpc_wake_up_task(task);
 995 }
 996
 997 /*
 998  * 5a.  Handle cleanup after a transmission
 999  */
1000 static void
1001 call_transmit_status(struct rpc_task *task)
1002 {
1003         task->tk_action = call_status;
1004         /*
1005          * Special case: if we've been waiting on the socket's write_space()
1006          * callback, then don't call xprt_end_transmit().
1007          */
1008         if (task->tk_status == -EAGAIN)
1009                 return;
1010         xprt_end_transmit(task);
1011         rpc_task_force_reencode(task);
1012 }
1013
1014 /*
1015  * 6.   Sort out the RPC call status
1016  */
1017 static void
1018 call_status(struct rpc_task *task)
1019 {
1020         struct rpc_clnt *clnt = task->tk_client;
1021         struct rpc_rqst *req = task->tk_rqstp;
1022         int             status;
1023
1024         if (req->rq_received > 0 && !req->rq_bytes_sent)
1025                 task->tk_status = req->rq_received;
1026
1027         dprintk("RPC: %4d call_status (status %d)\n",
1028                                 task->tk_pid, task->tk_status);
1029
1030         status = task->tk_status;
1031         if (status >= 0) {
1032                 task->tk_action = call_decode;
1033                 return;
1034         }
1035
1036         task->tk_status = 0;
1037         switch(status) {
1038         case -EHOSTDOWN:
1039         case -EHOSTUNREACH:
1040         case -ENETUNREACH:
1041                 /*
1042                  * Delay any retries for 3 seconds, then handle as if it
1043                  * were a timeout.
1044                  */
1045                 rpc_delay(task, 3*HZ);
1046         case -ETIMEDOUT:
1047                 task->tk_action = call_timeout;
1048                 break;
1049         case -ECONNREFUSED:
1050         case -ENOTCONN:
1051                 rpc_force_rebind(clnt);
1052                 task->tk_action = call_bind;
1053                 break;
1054         case -EAGAIN:
1055                 task->tk_action = call_transmit;
1056                 break;
1057         case -EIO:
1058                 /* shutdown or soft timeout */
1059                 rpc_exit(task, status);
1060                 break;
1061         default:
1062                 printk("%s: RPC call returned error %d\n",
1063                                clnt->cl_protname, -status);
1064                 rpc_exit(task, status);
1065         }
1066 }
1067
1068 /*
1069  * 6a.  Handle RPC timeout
1070  *      We do not release the request slot, so we keep using the
1071  *      same XID for all retransmits.
1072  */
1073 static void
1074 call_timeout(struct rpc_task *task)
1075 {
1076         struct rpc_clnt *clnt = task->tk_client;
1077
1078         if (xprt_adjust_timeout(task->tk_rqstp) == 0) {
1079                 dprintk("RPC: %4d call_timeout (minor)\n", task->tk_pid);
1080                 goto retry;
1081         }
1082
1083         dprintk("RPC: %4d call_timeout (major)\n", task->tk_pid);
1084         task->tk_timeouts++;
1085
1086         if (RPC_IS_SOFT(task)) {
1087                 printk(KERN_NOTICE "%s: server %s not responding, timed out\n",
1088                                 clnt->cl_protname, clnt->cl_server);
1089                 rpc_exit(task, -EIO);
1090                 return;
1091         }
1092
1093         if (!(task->tk_flags & RPC_CALL_MAJORSEEN)) {
1094                 task->tk_flags |= RPC_CALL_MAJORSEEN;
1095                 printk(KERN_NOTICE "%s: server %s not responding, still trying\n",
1096                         clnt->cl_protname, clnt->cl_server);
1097         }
1098         rpc_force_rebind(clnt);
1099
1100 retry:
1101         clnt->cl_stats->rpcretrans++;
1102         task->tk_action = call_bind;
1103         task->tk_status = 0;
1104 }
1105
1106 /*
1107  * 7.   Decode the RPC reply
1108  */
1109 static void
1110 call_decode(struct rpc_task *task)
1111 {
1112         struct rpc_clnt *clnt = task->tk_client;
1113         struct rpc_rqst *req = task->tk_rqstp;
1114         kxdrproc_t      decode = task->tk_msg.rpc_proc->p_decode;
1115         __be32          *p;
1116
1117         dprintk("RPC: %4d call_decode (status %d)\n",
1118                                 task->tk_pid, task->tk_status);
1119
1120         if (task->tk_flags & RPC_CALL_MAJORSEEN) {
1121                 printk(KERN_NOTICE "%s: server %s OK\n",
1122                         clnt->cl_protname, clnt->cl_server);
1123                 task->tk_flags &= ~RPC_CALL_MAJORSEEN;
1124         }
1125
1126         if (task->tk_status < 12) {
1127                 if (!RPC_IS_SOFT(task)) {
1128                         task->tk_action = call_bind;
1129                         clnt->cl_stats->rpcretrans++;
1130                         goto out_retry;
1131                 }
1132                 dprintk("%s: too small RPC reply size (%d bytes)\n",
1133                         clnt->cl_protname, task->tk_status);
1134                 task->tk_action = call_timeout;
1135                 goto out_retry;
1136         }
1137
1138         /*
1139          * Ensure that we see all writes made by xprt_complete_rqst()
1140          * before it changed req->rq_received.
1141          */
1142         smp_rmb();
1143         req->rq_rcv_buf.len = req->rq_private_buf.len;
1144
1145         /* Check that the softirq receive buffer is valid */
1146         WARN_ON(memcmp(&req->rq_rcv_buf, &req->rq_private_buf,
1147                                 sizeof(req->rq_rcv_buf)) != 0);
1148
1149         /* Verify the RPC header */
1150         p = call_verify(task);
1151         if (IS_ERR(p)) {
1152                 if (p == ERR_PTR(-EAGAIN))
1153                         goto out_retry;
1154                 return;
1155         }
1156
1157         task->tk_action = rpc_exit_task;
1158
1159         if (decode)
1160                 task->tk_status = rpcauth_unwrap_resp(task, decode, req, p,
1161                                                       task->tk_msg.rpc_resp);
1162         dprintk("RPC: %4d call_decode result %d\n", task->tk_pid,
1163                                         task->tk_status);
1164         return;
1165 out_retry:
1166         req->rq_received = req->rq_private_buf.len = 0;
1167         task->tk_status = 0;
1168 }
1169
1170 /*
1171  * 8.   Refresh the credentials if rejected by the server
1172  */
1173 static void
1174 call_refresh(struct rpc_task *task)
1175 {
1176         dprintk("RPC: %4d call_refresh\n", task->tk_pid);
1177
1178         xprt_release(task);     /* Must do to obtain new XID */
1179         task->tk_action = call_refreshresult;
1180         task->tk_status = 0;
1181         task->tk_client->cl_stats->rpcauthrefresh++;
1182         rpcauth_refreshcred(task);
1183 }
1184
1185 /*
1186  * 8a.  Process the results of a credential refresh
1187  */
1188 static void
1189 call_refreshresult(struct rpc_task *task)
1190 {
1191         int status = task->tk_status;
1192         dprintk("RPC: %4d call_refreshresult (status %d)\n",
1193                                 task->tk_pid, task->tk_status);
1194
1195         task->tk_status = 0;
1196         task->tk_action = call_reserve;
1197         if (status >= 0 && rpcauth_uptodatecred(task))
1198                 return;
1199         if (status == -EACCES) {
1200                 rpc_exit(task, -EACCES);
1201                 return;
1202         }
1203         task->tk_action = call_refresh;
1204         if (status != -ETIMEDOUT)
1205                 rpc_delay(task, 3*HZ);
1206         return;
1207 }
1208
1209 /*
1210  * Call header serialization
1211  */
1212 static __be32 *
1213 call_header(struct rpc_task *task)
1214 {
1215         struct rpc_clnt *clnt = task->tk_client;
1216         struct rpc_rqst *req = task->tk_rqstp;
1217         __be32          *p = req->rq_svec[0].iov_base;
1218
1219         /* FIXME: check buffer size? */
1220
1221         p = xprt_skip_transport_header(task->tk_xprt, p);
1222         *p++ = req->rq_xid;             /* XID */
1223         *p++ = htonl(RPC_CALL);         /* CALL */
1224         *p++ = htonl(RPC_VERSION);      /* RPC version */
1225         *p++ = htonl(clnt->cl_prog);    /* program number */
1226         *p++ = htonl(clnt->cl_vers);    /* program version */
1227         *p++ = htonl(task->tk_msg.rpc_proc->p_proc);    /* procedure */
1228         p = rpcauth_marshcred(task, p);
1229         req->rq_slen = xdr_adjust_iovec(&req->rq_svec[0], p);
1230         return p;
1231 }
1232
1233 /*
1234  * Reply header verification
1235  */
1236 static __be32 *
1237 call_verify(struct rpc_task *task)
1238 {
1239         struct kvec *iov = &task->tk_rqstp->rq_rcv_buf.head[0];
1240         int len = task->tk_rqstp->rq_rcv_buf.len >> 2;
1241         __be32  *p = iov->iov_base;
1242         u32 n;
1243         int error = -EACCES;
1244
1245         if ((task->tk_rqstp->rq_rcv_buf.len & 3) != 0) {
1246                 /* RFC-1014 says that the representation of XDR data must be a
1247                  * multiple of four bytes
1248                  * - if it isn't pointer subtraction in the NFS client may give
1249                  *   undefined results
1250                  */
1251                 printk(KERN_WARNING
1252                        "call_verify: XDR representation not a multiple of"
1253                        " 4 bytes: 0x%x\n", task->tk_rqstp->rq_rcv_buf.len);
1254                 goto out_eio;
1255         }
1256         if ((len -= 3) < 0)
1257                 goto out_overflow;
1258         p += 1; /* skip XID */
1259
1260         if ((n = ntohl(*p++)) != RPC_REPLY) {
1261                 printk(KERN_WARNING "call_verify: not an RPC reply: %x\n", n);
1262                 goto out_garbage;
1263         }
1264         if ((n = ntohl(*p++)) != RPC_MSG_ACCEPTED) {
1265                 if (--len < 0)
1266                         goto out_overflow;
1267                 switch ((n = ntohl(*p++))) {
1268                         case RPC_AUTH_ERROR:
1269                                 break;
1270                         case RPC_MISMATCH:
1271                                 dprintk("%s: RPC call version mismatch!\n", __FUNCTION__);
1272                                 error = -EPROTONOSUPPORT;
1273                                 goto out_err;
1274                         default:
1275                                 dprintk("%s: RPC call rejected, unknown error: %x\n", __FUNCTION__, n);
1276                                 goto out_eio;
1277                 }
1278                 if (--len < 0)
1279                         goto out_overflow;
1280                 switch ((n = ntohl(*p++))) {
1281                 case RPC_AUTH_REJECTEDCRED:
1282                 case RPC_AUTH_REJECTEDVERF:
1283                 case RPCSEC_GSS_CREDPROBLEM:
1284                 case RPCSEC_GSS_CTXPROBLEM:
1285                         if (!task->tk_cred_retry)
1286                                 break;
1287                         task->tk_cred_retry--;
1288                         dprintk("RPC: %4d call_verify: retry stale creds\n",
1289                                                         task->tk_pid);
1290                         rpcauth_invalcred(task);
1291                         task->tk_action = call_refresh;
1292                         goto out_retry;
1293                 case RPC_AUTH_BADCRED:
1294                 case RPC_AUTH_BADVERF:
1295                         /* possibly garbled cred/verf? */
1296                         if (!task->tk_garb_retry)
1297                                 break;
1298                         task->tk_garb_retry--;
1299                         dprintk("RPC: %4d call_verify: retry garbled creds\n",
1300                                                         task->tk_pid);
1301                         task->tk_action = call_bind;
1302                         goto out_retry;
1303                 case RPC_AUTH_TOOWEAK:
1304                         printk(KERN_NOTICE "call_verify: server %s requires stronger "
1305                                "authentication.\n", task->tk_client->cl_server);
1306                         break;
1307                 default:
1308                         printk(KERN_WARNING "call_verify: unknown auth error: %x\n", n);
1309                         error = -EIO;
1310                 }
1311                 dprintk("RPC: %4d call_verify: call rejected %d\n",
1312                                                 task->tk_pid, n);
1313                 goto out_err;
1314         }
1315         if (!(p = rpcauth_checkverf(task, p))) {
1316                 printk(KERN_WARNING "call_verify: auth check failed\n");
1317                 goto out_garbage;               /* bad verifier, retry */
1318         }
1319         len = p - (__be32 *)iov->iov_base - 1;
1320         if (len < 0)
1321                 goto out_overflow;
1322         switch ((n = ntohl(*p++))) {
1323         case RPC_SUCCESS:
1324                 return p;
1325         case RPC_PROG_UNAVAIL:
1326                 dprintk("RPC: call_verify: program %u is unsupported by server %s\n",
1327                                 (unsigned int)task->tk_client->cl_prog,
1328                                 task->tk_client->cl_server);
1329                 error = -EPFNOSUPPORT;
1330                 goto out_err;
1331         case RPC_PROG_MISMATCH:
1332                 dprintk("RPC: call_verify: program %u, version %u unsupported by server %s\n",
1333                                 (unsigned int)task->tk_client->cl_prog,
1334                                 (unsigned int)task->tk_client->cl_vers,
1335                                 task->tk_client->cl_server);
1336                 error = -EPROTONOSUPPORT;
1337                 goto out_err;
1338         case RPC_PROC_UNAVAIL:
1339                 dprintk("RPC: call_verify: proc %p unsupported by program %u, version %u on server %s\n",
1340                                 task->tk_msg.rpc_proc,
1341                                 task->tk_client->cl_prog,
1342                                 task->tk_client->cl_vers,
1343                                 task->tk_client->cl_server);
1344                 error = -EOPNOTSUPP;
1345                 goto out_err;
1346         case RPC_GARBAGE_ARGS:
1347                 dprintk("RPC: %4d %s: server saw garbage\n", task->tk_pid, __FUNCTION__);
1348                 break;                  /* retry */
1349         default:
1350                 printk(KERN_WARNING "call_verify: server accept status: %x\n", n);
1351                 /* Also retry */
1352         }
1353
1354 out_garbage:
1355         task->tk_client->cl_stats->rpcgarbage++;
1356         if (task->tk_garb_retry) {
1357                 task->tk_garb_retry--;
1358                 dprintk("RPC %s: retrying %4d\n", __FUNCTION__, task->tk_pid);
1359                 task->tk_action = call_bind;
1360 out_retry:
1361                 return ERR_PTR(-EAGAIN);
1362         }
1363         printk(KERN_WARNING "RPC %s: retry failed, exit EIO\n", __FUNCTION__);
1364 out_eio:
1365         error = -EIO;
1366 out_err:
1367         rpc_exit(task, error);
1368         return ERR_PTR(error);
1369 out_overflow:
1370         printk(KERN_WARNING "RPC %s: server reply was truncated.\n", __FUNCTION__);
1371         goto out_garbage;
1372 }
1373
1374 static int rpcproc_encode_null(void *rqstp, __be32 *data, void *obj)
1375 {
1376         return 0;
1377 }
1378
1379 static int rpcproc_decode_null(void *rqstp, __be32 *data, void *obj)
1380 {
1381         return 0;
1382 }
1383
1384 static struct rpc_procinfo rpcproc_null = {
1385         .p_encode = rpcproc_encode_null,
1386         .p_decode = rpcproc_decode_null,
1387 };
1388
1389 int rpc_ping(struct rpc_clnt *clnt, int flags)
1390 {
1391         struct rpc_message msg = {
1392                 .rpc_proc = &rpcproc_null,
1393         };
1394         int err;
1395         msg.rpc_cred = authnull_ops.lookup_cred(NULL, NULL, 0);
1396         err = rpc_call_sync(clnt, &msg, flags);
1397         put_rpccred(msg.rpc_cred);
1398         return err;
1399 }