drivers/staging/lustre/lustre/ptlrpc/pinger.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2012, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * lustre/ptlrpc/pinger.c
  37  *
  38  * Portal-RPC reconnection and replay operations, for use in recovery.
  39  */
  40
  41 #define DEBUG_SUBSYSTEM S_RPC
  42
  43 #include "../include/obd_support.h"
  44 #include "../include/obd_class.h"
  45 #include "ptlrpc_internal.h"
  46
  47 static int suppress_pings;
  48 module_param(suppress_pings, int, 0644);
  49 MODULE_PARM_DESC(suppress_pings, "Suppress pings");
  50
  51 struct mutex pinger_mutex;
  52 static LIST_HEAD(pinger_imports);
  53 static struct list_head timeout_list = LIST_HEAD_INIT(timeout_list);
  54
  55 int ptlrpc_pinger_suppress_pings(void)
  56 {
  57         return suppress_pings;
  58 }
  59 EXPORT_SYMBOL(ptlrpc_pinger_suppress_pings);
  60
  61 struct ptlrpc_request *
  62 ptlrpc_prep_ping(struct obd_import *imp)
  63 {
  64         struct ptlrpc_request *req;
  65
  66         req = ptlrpc_request_alloc_pack(imp, &RQF_OBD_PING,
  67                                         LUSTRE_OBD_VERSION, OBD_PING);
  68         if (req) {
  69                 ptlrpc_request_set_replen(req);
  70                 req->rq_no_resend = req->rq_no_delay = 1;
  71         }
  72         return req;
  73 }
  74
  75 int ptlrpc_obd_ping(struct obd_device *obd)
  76 {
  77         int rc;
  78         struct ptlrpc_request *req;
  79
  80         req = ptlrpc_prep_ping(obd->u.cli.cl_import);
  81         if (req == NULL)
  82                 return -ENOMEM;
  83
  84         req->rq_send_state = LUSTRE_IMP_FULL;
  85
  86         rc = ptlrpc_queue_wait(req);
  87
  88         ptlrpc_req_finished(req);
  89
  90         return rc;
  91 }
  92 EXPORT_SYMBOL(ptlrpc_obd_ping);
  93
  94 int ptlrpc_ping(struct obd_import *imp)
  95 {
  96         struct ptlrpc_request *req;
  97
  98         req = ptlrpc_prep_ping(imp);
  99         if (req == NULL) {
 100                 CERROR("OOM trying to ping %s->%s\n",
 101                        imp->imp_obd->obd_uuid.uuid,
 102                        obd2cli_tgt(imp->imp_obd));
 103                 return -ENOMEM;
 104         }
 105
 106         DEBUG_REQ(D_INFO, req, "pinging %s->%s",
 107                   imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 108         ptlrpcd_add_req(req, PDL_POLICY_ROUND, -1);
 109
 110         return 0;
 111 }
 112
 113 void ptlrpc_update_next_ping(struct obd_import *imp, int soon)
 114 {
 115         int time = soon ? PING_INTERVAL_SHORT : PING_INTERVAL;
 116         if (imp->imp_state == LUSTRE_IMP_DISCON) {
 117                 int dtime = max_t(int, CONNECTION_SWITCH_MIN,
 118                                   AT_OFF ? 0 :
 119                                   at_get(&imp->imp_at.iat_net_latency));
 120                 time = min(time, dtime);
 121         }
 122         imp->imp_next_ping = cfs_time_shift(time);
 123 }
 124
 125 void ptlrpc_ping_import_soon(struct obd_import *imp)
 126 {
 127         imp->imp_next_ping = cfs_time_current();
 128 }
 129
 130 static inline int imp_is_deactive(struct obd_import *imp)
 131 {
 132         return (imp->imp_deactive ||
 133                 OBD_FAIL_CHECK(OBD_FAIL_PTLRPC_IMP_DEACTIVE));
 134 }
 135
 136 static inline int ptlrpc_next_reconnect(struct obd_import *imp)
 137 {
 138         if (imp->imp_server_timeout)
 139                 return cfs_time_shift(obd_timeout / 2);
 140         else
 141                 return cfs_time_shift(obd_timeout);
 142 }
 143
 144 long pinger_check_timeout(unsigned long time)
 145 {
 146         struct timeout_item *item;
 147         unsigned long timeout = PING_INTERVAL;
 148
 149         /* The timeout list is a increase order sorted list */
 150         mutex_lock(&pinger_mutex);
 151         list_for_each_entry(item, &timeout_list, ti_chain) {
 152                 int ti_timeout = item->ti_timeout;
 153                 if (timeout > ti_timeout)
 154                         timeout = ti_timeout;
 155                 break;
 156         }
 157         mutex_unlock(&pinger_mutex);
 158
 159         return cfs_time_sub(cfs_time_add(time, cfs_time_seconds(timeout)),
 160                                          cfs_time_current());
 161 }
 162
 163 static bool ir_up;
 164
 165 void ptlrpc_pinger_ir_up(void)
 166 {
 167         CDEBUG(D_HA, "IR up\n");
 168         ir_up = true;
 169 }
 170 EXPORT_SYMBOL(ptlrpc_pinger_ir_up);
 171
 172 void ptlrpc_pinger_ir_down(void)
 173 {
 174         CDEBUG(D_HA, "IR down\n");
 175         ir_up = false;
 176 }
 177 EXPORT_SYMBOL(ptlrpc_pinger_ir_down);
 178
 179 static void ptlrpc_pinger_process_import(struct obd_import *imp,
 180                                          unsigned long this_ping)
 181 {
 182         int level;
 183         int force;
 184         int force_next;
 185         int suppress;
 186
 187         spin_lock(&imp->imp_lock);
 188
 189         level = imp->imp_state;
 190         force = imp->imp_force_verify;
 191         force_next = imp->imp_force_next_verify;
 192         /*
 193          * This will be used below only if the import is "FULL".
 194          */
 195         suppress = ir_up && OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS);
 196
 197         imp->imp_force_verify = 0;
 198
 199         if (cfs_time_aftereq(imp->imp_next_ping - 5 * CFS_TICK, this_ping) &&
 200             !force) {
 201                 spin_unlock(&imp->imp_lock);
 202                 return;
 203         }
 204
 205         imp->imp_force_next_verify = 0;
 206
 207         spin_unlock(&imp->imp_lock);
 208
 209         CDEBUG(level == LUSTRE_IMP_FULL ? D_INFO : D_HA, "%s->%s: level %s/%u "
 210                "force %u force_next %u deactive %u pingable %u suppress %u\n",
 211                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 212                ptlrpc_import_state_name(level), level, force, force_next,
 213                imp->imp_deactive, imp->imp_pingable, suppress);
 214
 215         if (level == LUSTRE_IMP_DISCON && !imp_is_deactive(imp)) {
 216                 /* wait for a while before trying recovery again */
 217                 imp->imp_next_ping = ptlrpc_next_reconnect(imp);
 218                 if (!imp->imp_no_pinger_recover)
 219                         ptlrpc_initiate_recovery(imp);
 220         } else if (level != LUSTRE_IMP_FULL ||
 221                    imp->imp_obd->obd_no_recov ||
 222                    imp_is_deactive(imp)) {
 223                 CDEBUG(D_HA, "%s->%s: not pinging (in recovery "
 224                        "or recovery disabled: %s)\n",
 225                        imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 226                        ptlrpc_import_state_name(level));
 227                 if (force) {
 228                         spin_lock(&imp->imp_lock);
 229                         imp->imp_force_verify = 1;
 230                         spin_unlock(&imp->imp_lock);
 231                 }
 232         } else if ((imp->imp_pingable && !suppress) || force_next || force) {
 233                 ptlrpc_ping(imp);
 234         }
 235 }
 236
 237 static int ptlrpc_pinger_main(void *arg)
 238 {
 239         struct ptlrpc_thread *thread = (struct ptlrpc_thread *)arg;
 240
 241         /* Record that the thread is running */
 242         thread_set_flags(thread, SVC_RUNNING);
 243         wake_up(&thread->t_ctl_waitq);
 244
 245         /* And now, loop forever, pinging as needed. */
 246         while (1) {
 247                 unsigned long this_ping = cfs_time_current();
 248                 struct l_wait_info lwi;
 249                 long time_to_next_wake;
 250                 struct timeout_item *item;
 251                 struct list_head *iter;
 252
 253                 mutex_lock(&pinger_mutex);
 254                 list_for_each_entry(item, &timeout_list, ti_chain) {
 255                         item->ti_cb(item, item->ti_cb_data);
 256                 }
 257                 list_for_each(iter, &pinger_imports) {
 258                         struct obd_import *imp =
 259                                 list_entry(iter, struct obd_import,
 260                                                imp_pinger_chain);
 261
 262                         ptlrpc_pinger_process_import(imp, this_ping);
 263                         /* obd_timeout might have changed */
 264                         if (imp->imp_pingable && imp->imp_next_ping &&
 265                             cfs_time_after(imp->imp_next_ping,
 266                                            cfs_time_add(this_ping,
 267                                                         cfs_time_seconds(PING_INTERVAL))))
 268                                 ptlrpc_update_next_ping(imp, 0);
 269                 }
 270                 mutex_unlock(&pinger_mutex);
 271                 /* update memory usage info */
 272                 obd_update_maxusage();
 273
 274                 /* Wait until the next ping time, or until we're stopped. */
 275                 time_to_next_wake = pinger_check_timeout(this_ping);
 276                 /* The ping sent by ptlrpc_send_rpc may get sent out
 277                    say .01 second after this.
 278                    ptlrpc_pinger_sending_on_import will then set the
 279                    next ping time to next_ping + .01 sec, which means
 280                    we will SKIP the next ping at next_ping, and the
 281                    ping will get sent 2 timeouts from now!  Beware. */
 282                 CDEBUG(D_INFO, "next wakeup in "CFS_DURATION_T" ("
 283                        CFS_TIME_T")\n", time_to_next_wake,
 284                        cfs_time_add(this_ping,
 285                                     cfs_time_seconds(PING_INTERVAL)));
 286                 if (time_to_next_wake > 0) {
 287                         lwi = LWI_TIMEOUT(max_t(long, time_to_next_wake,
 288                                                 cfs_time_seconds(1)),
 289                                           NULL, NULL);
 290                         l_wait_event(thread->t_ctl_waitq,
 291                                      thread_is_stopping(thread) ||
 292                                      thread_is_event(thread),
 293                                      &lwi);
 294                         if (thread_test_and_clear_flags(thread, SVC_STOPPING)) {
 295                                 break;
 296                         } else {
 297                                 /* woken after adding import to reset timer */
 298                                 thread_test_and_clear_flags(thread, SVC_EVENT);
 299                         }
 300                 }
 301         }
 302
 303         thread_set_flags(thread, SVC_STOPPED);
 304         wake_up(&thread->t_ctl_waitq);
 305
 306         CDEBUG(D_NET, "pinger thread exiting, process %d\n", current_pid());
 307         return 0;
 308 }
 309
 310 static struct ptlrpc_thread pinger_thread;
 311
 312 int ptlrpc_start_pinger(void)
 313 {
 314         struct l_wait_info lwi = { 0 };
 315         int rc;
 316
 317         if (!thread_is_init(&pinger_thread) &&
 318             !thread_is_stopped(&pinger_thread))
 319                 return -EALREADY;
 320
 321         init_waitqueue_head(&pinger_thread.t_ctl_waitq);
 322
 323         strcpy(pinger_thread.t_name, "ll_ping");
 324
 325         /* CLONE_VM and CLONE_FILES just avoid a needless copy, because we
 326          * just drop the VM and FILES in cfs_daemonize_ctxt() right away. */
 327         rc = PTR_ERR(kthread_run(ptlrpc_pinger_main, &pinger_thread,
 328                                  "%s", pinger_thread.t_name));
 329         if (IS_ERR_VALUE(rc)) {
 330                 CERROR("cannot start thread: %d\n", rc);
 331                 return rc;
 332         }
 333         l_wait_event(pinger_thread.t_ctl_waitq,
 334                      thread_is_running(&pinger_thread), &lwi);
 335
 336         if (suppress_pings)
 337                 CWARN("Pings will be suppressed at the request of the "
 338                       "administrator.  The configuration shall meet the "
 339                       "additional requirements described in the manual.  "
 340                       "(Search for the \"suppress_pings\" kernel module "
 341                       "parameter.)\n");
 342
 343         return 0;
 344 }
 345
 346 int ptlrpc_pinger_remove_timeouts(void);
 347
 348 int ptlrpc_stop_pinger(void)
 349 {
 350         struct l_wait_info lwi = { 0 };
 351         int rc = 0;
 352
 353         if (thread_is_init(&pinger_thread) ||
 354             thread_is_stopped(&pinger_thread))
 355                 return -EALREADY;
 356
 357         ptlrpc_pinger_remove_timeouts();
 358         thread_set_flags(&pinger_thread, SVC_STOPPING);
 359         wake_up(&pinger_thread.t_ctl_waitq);
 360
 361         l_wait_event(pinger_thread.t_ctl_waitq,
 362                      thread_is_stopped(&pinger_thread), &lwi);
 363
 364         return rc;
 365 }
 366
 367 void ptlrpc_pinger_sending_on_import(struct obd_import *imp)
 368 {
 369         ptlrpc_update_next_ping(imp, 0);
 370 }
 371 EXPORT_SYMBOL(ptlrpc_pinger_sending_on_import);
 372
 373 void ptlrpc_pinger_commit_expected(struct obd_import *imp)
 374 {
 375         ptlrpc_update_next_ping(imp, 1);
 376         assert_spin_locked(&imp->imp_lock);
 377         /*
 378          * Avoid reading stale imp_connect_data.  When not sure if pings are
 379          * expected or not on next connection, we assume they are not and force
 380          * one anyway to guarantee the chance of updating
 381          * imp_peer_committed_transno.
 382          */
 383         if (imp->imp_state != LUSTRE_IMP_FULL ||
 384             OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS))
 385                 imp->imp_force_next_verify = 1;
 386 }
 387
 388 int ptlrpc_pinger_add_import(struct obd_import *imp)
 389 {
 390         if (!list_empty(&imp->imp_pinger_chain))
 391                 return -EALREADY;
 392
 393         mutex_lock(&pinger_mutex);
 394         CDEBUG(D_HA, "adding pingable import %s->%s\n",
 395                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 396         /* if we add to pinger we want recovery on this import */
 397         imp->imp_obd->obd_no_recov = 0;
 398         ptlrpc_update_next_ping(imp, 0);
 399         /* XXX sort, blah blah */
 400         list_add_tail(&imp->imp_pinger_chain, &pinger_imports);
 401         class_import_get(imp);
 402
 403         ptlrpc_pinger_wake_up();
 404         mutex_unlock(&pinger_mutex);
 405
 406         return 0;
 407 }
 408 EXPORT_SYMBOL(ptlrpc_pinger_add_import);
 409
 410 int ptlrpc_pinger_del_import(struct obd_import *imp)
 411 {
 412         if (list_empty(&imp->imp_pinger_chain))
 413                 return -ENOENT;
 414
 415         mutex_lock(&pinger_mutex);
 416         list_del_init(&imp->imp_pinger_chain);
 417         CDEBUG(D_HA, "removing pingable import %s->%s\n",
 418                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 419         /* if we remove from pinger we don't want recovery on this import */
 420         imp->imp_obd->obd_no_recov = 1;
 421         class_import_put(imp);
 422         mutex_unlock(&pinger_mutex);
 423         return 0;
 424 }
 425 EXPORT_SYMBOL(ptlrpc_pinger_del_import);
 426
 427 /**
 428  * Register a timeout callback to the pinger list, and the callback will
 429  * be called when timeout happens.
 430  */
 431 struct timeout_item* ptlrpc_new_timeout(int time, enum timeout_event event,
 432                                         timeout_cb_t cb, void *data)
 433 {
 434         struct timeout_item *ti;
 435
 436         OBD_ALLOC_PTR(ti);
 437         if (!ti)
 438                 return NULL;
 439
 440         INIT_LIST_HEAD(&ti->ti_obd_list);
 441         INIT_LIST_HEAD(&ti->ti_chain);
 442         ti->ti_timeout = time;
 443         ti->ti_event = event;
 444         ti->ti_cb = cb;
 445         ti->ti_cb_data = data;
 446
 447         return ti;
 448 }
 449
 450 /**
 451  * Register timeout event on the the pinger thread.
 452  * Note: the timeout list is an sorted list with increased timeout value.
 453  */
 454 static struct timeout_item*
 455 ptlrpc_pinger_register_timeout(int time, enum timeout_event event,
 456                                timeout_cb_t cb, void *data)
 457 {
 458         struct timeout_item *item, *tmp;
 459
 460         LASSERT(mutex_is_locked(&pinger_mutex));
 461
 462         list_for_each_entry(item, &timeout_list, ti_chain)
 463                 if (item->ti_event == event)
 464                         goto out;
 465
 466         item = ptlrpc_new_timeout(time, event, cb, data);
 467         if (item) {
 468                 list_for_each_entry_reverse(tmp, &timeout_list, ti_chain) {
 469                         if (tmp->ti_timeout < time) {
 470                                 list_add(&item->ti_chain, &tmp->ti_chain);
 471                                 goto out;
 472                         }
 473                 }
 474                 list_add(&item->ti_chain, &timeout_list);
 475         }
 476 out:
 477         return item;
 478 }
 479
 480 /* Add a client_obd to the timeout event list, when timeout(@time)
 481  * happens, the callback(@cb) will be called.
 482  */
 483 int ptlrpc_add_timeout_client(int time, enum timeout_event event,
 484                               timeout_cb_t cb, void *data,
 485                               struct list_head *obd_list)
 486 {
 487         struct timeout_item *ti;
 488
 489         mutex_lock(&pinger_mutex);
 490         ti = ptlrpc_pinger_register_timeout(time, event, cb, data);
 491         if (!ti) {
 492                 mutex_unlock(&pinger_mutex);
 493                 return -EINVAL;
 494         }
 495         list_add(obd_list, &ti->ti_obd_list);
 496         mutex_unlock(&pinger_mutex);
 497         return 0;
 498 }
 499 EXPORT_SYMBOL(ptlrpc_add_timeout_client);
 500
 501 int ptlrpc_del_timeout_client(struct list_head *obd_list,
 502                               enum timeout_event event)
 503 {
 504         struct timeout_item *ti = NULL, *item;
 505
 506         if (list_empty(obd_list))
 507                 return 0;
 508         mutex_lock(&pinger_mutex);
 509         list_del_init(obd_list);
 510         /**
 511          * If there are no obd attached to the timeout event
 512          * list, remove this timeout event from the pinger
 513          */
 514         list_for_each_entry(item, &timeout_list, ti_chain) {
 515                 if (item->ti_event == event) {
 516                         ti = item;
 517                         break;
 518                 }
 519         }
 520         LASSERTF(ti != NULL, "ti is NULL !\n");
 521         if (list_empty(&ti->ti_obd_list)) {
 522                 list_del(&ti->ti_chain);
 523                 OBD_FREE_PTR(ti);
 524         }
 525         mutex_unlock(&pinger_mutex);
 526         return 0;
 527 }
 528 EXPORT_SYMBOL(ptlrpc_del_timeout_client);
 529
 530 int ptlrpc_pinger_remove_timeouts(void)
 531 {
 532         struct timeout_item *item, *tmp;
 533
 534         mutex_lock(&pinger_mutex);
 535         list_for_each_entry_safe(item, tmp, &timeout_list, ti_chain) {
 536                 LASSERT(list_empty(&item->ti_obd_list));
 537                 list_del(&item->ti_chain);
 538                 OBD_FREE_PTR(item);
 539         }
 540         mutex_unlock(&pinger_mutex);
 541         return 0;
 542 }
 543
 544 void ptlrpc_pinger_wake_up(void)
 545 {
 546         thread_add_flags(&pinger_thread, SVC_EVENT);
 547         wake_up(&pinger_thread.t_ctl_waitq);
 548 }
 549
 550 /* Ping evictor thread */
 551 #define PET_READY     1
 552 #define PET_TERMINATE 2
 553
 554 static int             pet_refcount = 0;
 555 static int             pet_state;
 556 static wait_queue_head_t       pet_waitq;
 557 LIST_HEAD(pet_list);
 558 static DEFINE_SPINLOCK(pet_lock);
 559
 560 int ping_evictor_wake(struct obd_export *exp)
 561 {
 562         struct obd_device *obd;
 563
 564         spin_lock(&pet_lock);
 565         if (pet_state != PET_READY) {
 566                 /* eventually the new obd will call here again. */
 567                 spin_unlock(&pet_lock);
 568                 return 1;
 569         }
 570
 571         obd = class_exp2obd(exp);
 572         if (list_empty(&obd->obd_evict_list)) {
 573                 class_incref(obd, "evictor", obd);
 574                 list_add(&obd->obd_evict_list, &pet_list);
 575         }
 576         spin_unlock(&pet_lock);
 577
 578         wake_up(&pet_waitq);
 579         return 0;
 580 }
 581
 582 static int ping_evictor_main(void *arg)
 583 {
 584         struct obd_device *obd;
 585         struct obd_export *exp;
 586         struct l_wait_info lwi = { 0 };
 587         time_t expire_time;
 588
 589         unshare_fs_struct();
 590
 591         CDEBUG(D_HA, "Starting Ping Evictor\n");
 592         pet_state = PET_READY;
 593         while (1) {
 594                 l_wait_event(pet_waitq, (!list_empty(&pet_list)) ||
 595                              (pet_state == PET_TERMINATE), &lwi);
 596
 597                 /* loop until all obd's will be removed */
 598                 if ((pet_state == PET_TERMINATE) && list_empty(&pet_list))
 599                         break;
 600
 601                 /* we only get here if pet_exp != NULL, and the end of this
 602                  * loop is the only place which sets it NULL again, so lock
 603                  * is not strictly necessary. */
 604                 spin_lock(&pet_lock);
 605                 obd = list_entry(pet_list.next, struct obd_device,
 606                                      obd_evict_list);
 607                 spin_unlock(&pet_lock);
 608
 609                 expire_time = get_seconds() - PING_EVICT_TIMEOUT;
 610
 611                 CDEBUG(D_HA, "evicting all exports of obd %s older than %ld\n",
 612                        obd->obd_name, expire_time);
 613
 614                 /* Exports can't be deleted out of the list while we hold
 615                  * the obd lock (class_unlink_export), which means we can't
 616                  * lose the last ref on the export.  If they've already been
 617                  * removed from the list, we won't find them here. */
 618                 spin_lock(&obd->obd_dev_lock);
 619                 while (!list_empty(&obd->obd_exports_timed)) {
 620                         exp = list_entry(obd->obd_exports_timed.next,
 621                                              struct obd_export,
 622                                              exp_obd_chain_timed);
 623                         if (expire_time > exp->exp_last_request_time) {
 624                                 class_export_get(exp);
 625                                 spin_unlock(&obd->obd_dev_lock);
 626                                 LCONSOLE_WARN("%s: haven't heard from client %s"
 627                                               " (at %s) in %ld seconds. I think"
 628                                               " it's dead, and I am evicting"
 629                                               " it. exp %p, cur %ld expire %ld"
 630                                               " last %ld\n",
 631                                               obd->obd_name,
 632                                               obd_uuid2str(&exp->exp_client_uuid),
 633                                               obd_export_nid2str(exp),
 634                                               (long)(get_seconds() -
 635                                                      exp->exp_last_request_time),
 636                                               exp, (long)get_seconds(),
 637                                               (long)expire_time,
 638                                               (long)exp->exp_last_request_time);
 639                                 CDEBUG(D_HA, "Last request was at %ld\n",
 640                                        exp->exp_last_request_time);
 641                                 class_fail_export(exp);
 642                                 class_export_put(exp);
 643                                 spin_lock(&obd->obd_dev_lock);
 644                         } else {
 645                                 /* List is sorted, so everyone below is ok */
 646                                 break;
 647                         }
 648                 }
 649                 spin_unlock(&obd->obd_dev_lock);
 650
 651                 spin_lock(&pet_lock);
 652                 list_del_init(&obd->obd_evict_list);
 653                 spin_unlock(&pet_lock);
 654
 655                 class_decref(obd, "evictor", obd);
 656         }
 657         CDEBUG(D_HA, "Exiting Ping Evictor\n");
 658
 659         return 0;
 660 }
 661
 662 void ping_evictor_start(void)
 663 {
 664         struct task_struct *task;
 665
 666         if (++pet_refcount > 1)
 667                 return;
 668
 669         init_waitqueue_head(&pet_waitq);
 670
 671         task = kthread_run(ping_evictor_main, NULL, "ll_evictor");
 672         if (IS_ERR(task)) {
 673                 pet_refcount--;
 674                 CERROR("Cannot start ping evictor thread: %ld\n",
 675                         PTR_ERR(task));
 676         }
 677 }
 678 EXPORT_SYMBOL(ping_evictor_start);
 679
 680 void ping_evictor_stop(void)
 681 {
 682         if (--pet_refcount > 0)
 683                 return;
 684
 685         pet_state = PET_TERMINATE;
 686         wake_up(&pet_waitq);
 687 }
 688 EXPORT_SYMBOL(ping_evictor_stop);