kernel/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 force %u force_next %u deactive %u pingable %u suppress %u\n",
 210                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 211                ptlrpc_import_state_name(level), level, force, force_next,
 212                imp->imp_deactive, imp->imp_pingable, suppress);
 213
 214         if (level == LUSTRE_IMP_DISCON && !imp_is_deactive(imp)) {
 215                 /* wait for a while before trying recovery again */
 216                 imp->imp_next_ping = ptlrpc_next_reconnect(imp);
 217                 if (!imp->imp_no_pinger_recover)
 218                         ptlrpc_initiate_recovery(imp);
 219         } else if (level != LUSTRE_IMP_FULL ||
 220                    imp->imp_obd->obd_no_recov ||
 221                    imp_is_deactive(imp)) {
 222                 CDEBUG(D_HA, "%s->%s: not pinging (in recovery or recovery disabled: %s)\n",
 223                        imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 224                        ptlrpc_import_state_name(level));
 225                 if (force) {
 226                         spin_lock(&imp->imp_lock);
 227                         imp->imp_force_verify = 1;
 228                         spin_unlock(&imp->imp_lock);
 229                 }
 230         } else if ((imp->imp_pingable && !suppress) || force_next || force) {
 231                 ptlrpc_ping(imp);
 232         }
 233 }
 234
 235 static int ptlrpc_pinger_main(void *arg)
 236 {
 237         struct ptlrpc_thread *thread = (struct ptlrpc_thread *)arg;
 238
 239         /* Record that the thread is running */
 240         thread_set_flags(thread, SVC_RUNNING);
 241         wake_up(&thread->t_ctl_waitq);
 242
 243         /* And now, loop forever, pinging as needed. */
 244         while (1) {
 245                 unsigned long this_ping = cfs_time_current();
 246                 struct l_wait_info lwi;
 247                 long time_to_next_wake;
 248                 struct timeout_item *item;
 249                 struct list_head *iter;
 250
 251                 mutex_lock(&pinger_mutex);
 252                 list_for_each_entry(item, &timeout_list, ti_chain) {
 253                         item->ti_cb(item, item->ti_cb_data);
 254                 }
 255                 list_for_each(iter, &pinger_imports) {
 256                         struct obd_import *imp =
 257                                 list_entry(iter, struct obd_import,
 258                                                imp_pinger_chain);
 259
 260                         ptlrpc_pinger_process_import(imp, this_ping);
 261                         /* obd_timeout might have changed */
 262                         if (imp->imp_pingable && imp->imp_next_ping &&
 263                             cfs_time_after(imp->imp_next_ping,
 264                                            cfs_time_add(this_ping,
 265                                                         cfs_time_seconds(PING_INTERVAL))))
 266                                 ptlrpc_update_next_ping(imp, 0);
 267                 }
 268                 mutex_unlock(&pinger_mutex);
 269                 /* update memory usage info */
 270                 obd_update_maxusage();
 271
 272                 /* Wait until the next ping time, or until we're stopped. */
 273                 time_to_next_wake = pinger_check_timeout(this_ping);
 274                 /* The ping sent by ptlrpc_send_rpc may get sent out
 275                    say .01 second after this.
 276                    ptlrpc_pinger_sending_on_import will then set the
 277                    next ping time to next_ping + .01 sec, which means
 278                    we will SKIP the next ping at next_ping, and the
 279                    ping will get sent 2 timeouts from now!  Beware. */
 280                 CDEBUG(D_INFO, "next wakeup in "CFS_DURATION_T" ("
 281                        CFS_TIME_T")\n", time_to_next_wake,
 282                        cfs_time_add(this_ping,
 283                                     cfs_time_seconds(PING_INTERVAL)));
 284                 if (time_to_next_wake > 0) {
 285                         lwi = LWI_TIMEOUT(max_t(long, time_to_next_wake,
 286                                                 cfs_time_seconds(1)),
 287                                           NULL, NULL);
 288                         l_wait_event(thread->t_ctl_waitq,
 289                                      thread_is_stopping(thread) ||
 290                                      thread_is_event(thread),
 291                                      &lwi);
 292                         if (thread_test_and_clear_flags(thread, SVC_STOPPING)) {
 293                                 break;
 294                         } else {
 295                                 /* woken after adding import to reset timer */
 296                                 thread_test_and_clear_flags(thread, SVC_EVENT);
 297                         }
 298                 }
 299         }
 300
 301         thread_set_flags(thread, SVC_STOPPED);
 302         wake_up(&thread->t_ctl_waitq);
 303
 304         CDEBUG(D_NET, "pinger thread exiting, process %d\n", current_pid());
 305         return 0;
 306 }
 307
 308 static struct ptlrpc_thread pinger_thread;
 309
 310 int ptlrpc_start_pinger(void)
 311 {
 312         struct l_wait_info lwi = { 0 };
 313         int rc;
 314
 315         if (!thread_is_init(&pinger_thread) &&
 316             !thread_is_stopped(&pinger_thread))
 317                 return -EALREADY;
 318
 319         init_waitqueue_head(&pinger_thread.t_ctl_waitq);
 320
 321         strcpy(pinger_thread.t_name, "ll_ping");
 322
 323         /* CLONE_VM and CLONE_FILES just avoid a needless copy, because we
 324          * just drop the VM and FILES in cfs_daemonize_ctxt() right away. */
 325         rc = PTR_ERR(kthread_run(ptlrpc_pinger_main, &pinger_thread,
 326                                  "%s", pinger_thread.t_name));
 327         if (IS_ERR_VALUE(rc)) {
 328                 CERROR("cannot start thread: %d\n", rc);
 329                 return rc;
 330         }
 331         l_wait_event(pinger_thread.t_ctl_waitq,
 332                      thread_is_running(&pinger_thread), &lwi);
 333
 334         if (suppress_pings)
 335                 CWARN("Pings will be suppressed at the request of the administrator.  The configuration shall meet the additional requirements described in the manual.  (Search for the \"suppress_pings\" kernel module parameter.)\n");
 336
 337         return 0;
 338 }
 339
 340 int ptlrpc_pinger_remove_timeouts(void);
 341
 342 int ptlrpc_stop_pinger(void)
 343 {
 344         struct l_wait_info lwi = { 0 };
 345         int rc = 0;
 346
 347         if (thread_is_init(&pinger_thread) ||
 348             thread_is_stopped(&pinger_thread))
 349                 return -EALREADY;
 350
 351         ptlrpc_pinger_remove_timeouts();
 352         thread_set_flags(&pinger_thread, SVC_STOPPING);
 353         wake_up(&pinger_thread.t_ctl_waitq);
 354
 355         l_wait_event(pinger_thread.t_ctl_waitq,
 356                      thread_is_stopped(&pinger_thread), &lwi);
 357
 358         return rc;
 359 }
 360
 361 void ptlrpc_pinger_sending_on_import(struct obd_import *imp)
 362 {
 363         ptlrpc_update_next_ping(imp, 0);
 364 }
 365 EXPORT_SYMBOL(ptlrpc_pinger_sending_on_import);
 366
 367 void ptlrpc_pinger_commit_expected(struct obd_import *imp)
 368 {
 369         ptlrpc_update_next_ping(imp, 1);
 370         assert_spin_locked(&imp->imp_lock);
 371         /*
 372          * Avoid reading stale imp_connect_data.  When not sure if pings are
 373          * expected or not on next connection, we assume they are not and force
 374          * one anyway to guarantee the chance of updating
 375          * imp_peer_committed_transno.
 376          */
 377         if (imp->imp_state != LUSTRE_IMP_FULL ||
 378             OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS))
 379                 imp->imp_force_next_verify = 1;
 380 }
 381
 382 int ptlrpc_pinger_add_import(struct obd_import *imp)
 383 {
 384         if (!list_empty(&imp->imp_pinger_chain))
 385                 return -EALREADY;
 386
 387         mutex_lock(&pinger_mutex);
 388         CDEBUG(D_HA, "adding pingable import %s->%s\n",
 389                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 390         /* if we add to pinger we want recovery on this import */
 391         imp->imp_obd->obd_no_recov = 0;
 392         ptlrpc_update_next_ping(imp, 0);
 393         /* XXX sort, blah blah */
 394         list_add_tail(&imp->imp_pinger_chain, &pinger_imports);
 395         class_import_get(imp);
 396
 397         ptlrpc_pinger_wake_up();
 398         mutex_unlock(&pinger_mutex);
 399
 400         return 0;
 401 }
 402 EXPORT_SYMBOL(ptlrpc_pinger_add_import);
 403
 404 int ptlrpc_pinger_del_import(struct obd_import *imp)
 405 {
 406         if (list_empty(&imp->imp_pinger_chain))
 407                 return -ENOENT;
 408
 409         mutex_lock(&pinger_mutex);
 410         list_del_init(&imp->imp_pinger_chain);
 411         CDEBUG(D_HA, "removing pingable import %s->%s\n",
 412                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 413         /* if we remove from pinger we don't want recovery on this import */
 414         imp->imp_obd->obd_no_recov = 1;
 415         class_import_put(imp);
 416         mutex_unlock(&pinger_mutex);
 417         return 0;
 418 }
 419 EXPORT_SYMBOL(ptlrpc_pinger_del_import);
 420
 421 /**
 422  * Register a timeout callback to the pinger list, and the callback will
 423  * be called when timeout happens.
 424  */
 425 struct timeout_item *ptlrpc_new_timeout(int time, enum timeout_event event,
 426                                         timeout_cb_t cb, void *data)
 427 {
 428         struct timeout_item *ti;
 429
 430         OBD_ALLOC_PTR(ti);
 431         if (!ti)
 432                 return NULL;
 433
 434         INIT_LIST_HEAD(&ti->ti_obd_list);
 435         INIT_LIST_HEAD(&ti->ti_chain);
 436         ti->ti_timeout = time;
 437         ti->ti_event = event;
 438         ti->ti_cb = cb;
 439         ti->ti_cb_data = data;
 440
 441         return ti;
 442 }
 443
 444 /**
 445  * Register timeout event on the pinger thread.
 446  * Note: the timeout list is an sorted list with increased timeout value.
 447  */
 448 static struct timeout_item*
 449 ptlrpc_pinger_register_timeout(int time, enum timeout_event event,
 450                                timeout_cb_t cb, void *data)
 451 {
 452         struct timeout_item *item, *tmp;
 453
 454         LASSERT(mutex_is_locked(&pinger_mutex));
 455
 456         list_for_each_entry(item, &timeout_list, ti_chain)
 457                 if (item->ti_event == event)
 458                         goto out;
 459
 460         item = ptlrpc_new_timeout(time, event, cb, data);
 461         if (item) {
 462                 list_for_each_entry_reverse(tmp, &timeout_list, ti_chain) {
 463                         if (tmp->ti_timeout < time) {
 464                                 list_add(&item->ti_chain, &tmp->ti_chain);
 465                                 goto out;
 466                         }
 467                 }
 468                 list_add(&item->ti_chain, &timeout_list);
 469         }
 470 out:
 471         return item;
 472 }
 473
 474 /* Add a client_obd to the timeout event list, when timeout(@time)
 475  * happens, the callback(@cb) will be called.
 476  */
 477 int ptlrpc_add_timeout_client(int time, enum timeout_event event,
 478                               timeout_cb_t cb, void *data,
 479                               struct list_head *obd_list)
 480 {
 481         struct timeout_item *ti;
 482
 483         mutex_lock(&pinger_mutex);
 484         ti = ptlrpc_pinger_register_timeout(time, event, cb, data);
 485         if (!ti) {
 486                 mutex_unlock(&pinger_mutex);
 487                 return -EINVAL;
 488         }
 489         list_add(obd_list, &ti->ti_obd_list);
 490         mutex_unlock(&pinger_mutex);
 491         return 0;
 492 }
 493 EXPORT_SYMBOL(ptlrpc_add_timeout_client);
 494
 495 int ptlrpc_del_timeout_client(struct list_head *obd_list,
 496                               enum timeout_event event)
 497 {
 498         struct timeout_item *ti = NULL, *item;
 499
 500         if (list_empty(obd_list))
 501                 return 0;
 502         mutex_lock(&pinger_mutex);
 503         list_del_init(obd_list);
 504         /**
 505          * If there are no obd attached to the timeout event
 506          * list, remove this timeout event from the pinger
 507          */
 508         list_for_each_entry(item, &timeout_list, ti_chain) {
 509                 if (item->ti_event == event) {
 510                         ti = item;
 511                         break;
 512                 }
 513         }
 514         LASSERTF(ti != NULL, "ti is NULL !\n");
 515         if (list_empty(&ti->ti_obd_list)) {
 516                 list_del(&ti->ti_chain);
 517                 OBD_FREE_PTR(ti);
 518         }
 519         mutex_unlock(&pinger_mutex);
 520         return 0;
 521 }
 522 EXPORT_SYMBOL(ptlrpc_del_timeout_client);
 523
 524 int ptlrpc_pinger_remove_timeouts(void)
 525 {
 526         struct timeout_item *item, *tmp;
 527
 528         mutex_lock(&pinger_mutex);
 529         list_for_each_entry_safe(item, tmp, &timeout_list, ti_chain) {
 530                 LASSERT(list_empty(&item->ti_obd_list));
 531                 list_del(&item->ti_chain);
 532                 OBD_FREE_PTR(item);
 533         }
 534         mutex_unlock(&pinger_mutex);
 535         return 0;
 536 }
 537
 538 void ptlrpc_pinger_wake_up(void)
 539 {
 540         thread_add_flags(&pinger_thread, SVC_EVENT);
 541         wake_up(&pinger_thread.t_ctl_waitq);
 542 }
 543
 544 /* Ping evictor thread */
 545 #define PET_READY     1
 546 #define PET_TERMINATE 2
 547
 548 static int pet_refcount;
 549 static int             pet_state;
 550 static wait_queue_head_t       pet_waitq;
 551 LIST_HEAD(pet_list);
 552 static DEFINE_SPINLOCK(pet_lock);
 553
 554 int ping_evictor_wake(struct obd_export *exp)
 555 {
 556         struct obd_device *obd;
 557
 558         spin_lock(&pet_lock);
 559         if (pet_state != PET_READY) {
 560                 /* eventually the new obd will call here again. */
 561                 spin_unlock(&pet_lock);
 562                 return 1;
 563         }
 564
 565         obd = class_exp2obd(exp);
 566         if (list_empty(&obd->obd_evict_list)) {
 567                 class_incref(obd, "evictor", obd);
 568                 list_add(&obd->obd_evict_list, &pet_list);
 569         }
 570         spin_unlock(&pet_lock);
 571
 572         wake_up(&pet_waitq);
 573         return 0;
 574 }
 575
 576 static int ping_evictor_main(void *arg)
 577 {
 578         struct obd_device *obd;
 579         struct obd_export *exp;
 580         struct l_wait_info lwi = { 0 };
 581         time_t expire_time;
 582
 583         unshare_fs_struct();
 584
 585         CDEBUG(D_HA, "Starting Ping Evictor\n");
 586         pet_state = PET_READY;
 587         while (1) {
 588                 l_wait_event(pet_waitq, (!list_empty(&pet_list)) ||
 589                              (pet_state == PET_TERMINATE), &lwi);
 590
 591                 /* loop until all obd's will be removed */
 592                 if ((pet_state == PET_TERMINATE) && list_empty(&pet_list))
 593                         break;
 594
 595                 /* we only get here if pet_exp != NULL, and the end of this
 596                  * loop is the only place which sets it NULL again, so lock
 597                  * is not strictly necessary. */
 598                 spin_lock(&pet_lock);
 599                 obd = list_entry(pet_list.next, struct obd_device,
 600                                      obd_evict_list);
 601                 spin_unlock(&pet_lock);
 602
 603                 expire_time = get_seconds() - PING_EVICT_TIMEOUT;
 604
 605                 CDEBUG(D_HA, "evicting all exports of obd %s older than %ld\n",
 606                        obd->obd_name, expire_time);
 607
 608                 /* Exports can't be deleted out of the list while we hold
 609                  * the obd lock (class_unlink_export), which means we can't
 610                  * lose the last ref on the export.  If they've already been
 611                  * removed from the list, we won't find them here. */
 612                 spin_lock(&obd->obd_dev_lock);
 613                 while (!list_empty(&obd->obd_exports_timed)) {
 614                         exp = list_entry(obd->obd_exports_timed.next,
 615                                              struct obd_export,
 616                                              exp_obd_chain_timed);
 617                         if (expire_time > exp->exp_last_request_time) {
 618                                 class_export_get(exp);
 619                                 spin_unlock(&obd->obd_dev_lock);
 620                                 LCONSOLE_WARN("%s: haven't heard from client %s (at %s) in %ld seconds. I think it's dead, and I am evicting it. exp %p, cur %ld expire %ld last %ld\n",
 621                                               obd->obd_name,
 622                                               obd_uuid2str(&exp->exp_client_uuid),
 623                                               obd_export_nid2str(exp),
 624                                               (long)(get_seconds() -
 625                                                      exp->exp_last_request_time),
 626                                               exp, (long)get_seconds(),
 627                                               (long)expire_time,
 628                                               (long)exp->exp_last_request_time);
 629                                 CDEBUG(D_HA, "Last request was at %ld\n",
 630                                        exp->exp_last_request_time);
 631                                 class_fail_export(exp);
 632                                 class_export_put(exp);
 633                                 spin_lock(&obd->obd_dev_lock);
 634                         } else {
 635                                 /* List is sorted, so everyone below is ok */
 636                                 break;
 637                         }
 638                 }
 639                 spin_unlock(&obd->obd_dev_lock);
 640
 641                 spin_lock(&pet_lock);
 642                 list_del_init(&obd->obd_evict_list);
 643                 spin_unlock(&pet_lock);
 644
 645                 class_decref(obd, "evictor", obd);
 646         }
 647         CDEBUG(D_HA, "Exiting Ping Evictor\n");
 648
 649         return 0;
 650 }
 651
 652 void ping_evictor_start(void)
 653 {
 654         struct task_struct *task;
 655
 656         if (++pet_refcount > 1)
 657                 return;
 658
 659         init_waitqueue_head(&pet_waitq);
 660
 661         task = kthread_run(ping_evictor_main, NULL, "ll_evictor");
 662         if (IS_ERR(task)) {
 663                 pet_refcount--;
 664                 CERROR("Cannot start ping evictor thread: %ld\n",
 665                         PTR_ERR(task));
 666         }
 667 }
 668 EXPORT_SYMBOL(ping_evictor_start);
 669
 670 void ping_evictor_stop(void)
 671 {
 672         if (--pet_refcount > 0)
 673                 return;
 674
 675         pet_state = PET_TERMINATE;
 676         wake_up(&pet_waitq);
 677 }
 678 EXPORT_SYMBOL(ping_evictor_stop);