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.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2011, 2015, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  * Lustre is a trademark of Sun Microsystems, Inc.
  31  *
  32  * lustre/ptlrpc/pinger.c
  33  *
  34  * Portal-RPC reconnection and replay operations, for use in recovery.
  35  */
  36
  37 #define DEBUG_SUBSYSTEM S_RPC
  38
  39 #include <linux/kthread.h>
  40 #include <linux/workqueue.h>
  41 #include <obd_support.h>
  42 #include <obd_class.h>
  43 #include "ptlrpc_internal.h"
  44
  45 static int suppress_pings;
  46 module_param(suppress_pings, int, 0644);
  47 MODULE_PARM_DESC(suppress_pings, "Suppress pings");
  48
  49 struct mutex pinger_mutex;
  50 static struct list_head pinger_imports =
  51                 LIST_HEAD_INIT(pinger_imports);
  52 static struct list_head timeout_list =
  53                 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         ENTRY;
  81
  82         req = ptlrpc_prep_ping(obd->u.cli.cl_import);
  83         if (!req)
  84                 RETURN(-ENOMEM);
  85
  86         req->rq_send_state = LUSTRE_IMP_FULL;
  87
  88         rc = ptlrpc_queue_wait(req);
  89
  90         ptlrpc_req_finished(req);
  91
  92         RETURN(rc);
  93 }
  94 EXPORT_SYMBOL(ptlrpc_obd_ping);
  95
  96 static bool ptlrpc_check_import_is_idle(struct obd_import *imp)
  97 {
  98         struct ldlm_namespace *ns = imp->imp_obd->obd_namespace;
  99         time64_t now;
 100
 101         if (!imp->imp_idle_timeout)
 102                 return false;
 103
 104         /*
 105          * 4 comes from:
 106          *  - client_obd_setup() - hashed import
 107          *  - ptlrpcd_alloc_work()
 108          *  - ptlrpcd_alloc_work()
 109          *  - ptlrpc_pinger_add_import
 110          */
 111         if (atomic_read(&imp->imp_refcount) > 4)
 112                 return false;
 113
 114         /* any lock increases ns_bref being a resource holder */
 115         if (ns && atomic_read(&ns->ns_bref) > 0)
 116                 return false;
 117
 118         now = ktime_get_real_seconds();
 119         if (now - imp->imp_last_reply_time < imp->imp_idle_timeout)
 120                 return false;
 121
 122         return true;
 123 }
 124
 125 static int ptlrpc_ping(struct obd_import *imp)
 126 {
 127         struct ptlrpc_request *req;
 128
 129         ENTRY;
 130
 131         if (ptlrpc_check_import_is_idle(imp))
 132                 RETURN(ptlrpc_disconnect_and_idle_import(imp));
 133
 134         req = ptlrpc_prep_ping(imp);
 135         if (!req) {
 136                 CERROR("OOM trying to ping %s->%s\n",
 137                        imp->imp_obd->obd_uuid.uuid,
 138                        obd2cli_tgt(imp->imp_obd));
 139                 RETURN(-ENOMEM);
 140         }
 141
 142         DEBUG_REQ(D_INFO, req, "pinging %s->%s",
 143                   imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 144         ptlrpcd_add_req(req);
 145
 146         RETURN(0);
 147 }
 148
 149 static void ptlrpc_update_next_ping(struct obd_import *imp, int soon)
 150 {
 151 #ifdef ENABLE_PINGER
 152         time64_t time = soon ? PING_INTERVAL_SHORT : PING_INTERVAL;
 153
 154         if (imp->imp_state == LUSTRE_IMP_DISCON) {
 155                 time64_t dtime = max_t(time64_t, CONNECTION_SWITCH_MIN,
 156                                        AT_OFF ? 0 :
 157                                        at_get(&imp->imp_at.iat_net_latency));
 158                 time = min(time, dtime);
 159         }
 160         imp->imp_next_ping = ktime_get_seconds() + time;
 161 #endif /* ENABLE_PINGER */
 162 }
 163
 164 void ptlrpc_ping_import_soon(struct obd_import *imp)
 165 {
 166         imp->imp_next_ping = ktime_get_seconds();
 167 }
 168
 169 static inline int imp_is_deactive(struct obd_import *imp)
 170 {
 171         return imp->imp_deactive ||
 172                OBD_FAIL_CHECK(OBD_FAIL_PTLRPC_IMP_DEACTIVE);
 173 }
 174
 175 static inline time64_t ptlrpc_next_reconnect(struct obd_import *imp)
 176 {
 177         if (imp->imp_server_timeout)
 178                 return ktime_get_seconds() + (obd_timeout >> 1);
 179         else
 180                 return ktime_get_seconds() + obd_timeout;
 181 }
 182
 183 static time64_t pinger_check_timeout(time64_t time)
 184 {
 185         struct timeout_item *item;
 186         time64_t timeout = PING_INTERVAL;
 187
 188         /* This list is sorted in increasing timeout order */
 189         mutex_lock(&pinger_mutex);
 190         list_for_each_entry(item, &timeout_list, ti_chain) {
 191                 time64_t ti_timeout = item->ti_timeout;
 192
 193                 if (timeout > ti_timeout)
 194                         timeout = ti_timeout;
 195                 break;
 196         }
 197         mutex_unlock(&pinger_mutex);
 198
 199         return time + timeout - ktime_get_seconds();
 200 }
 201
 202 static bool ir_up;
 203
 204 void ptlrpc_pinger_ir_up(void)
 205 {
 206         CDEBUG(D_HA, "IR up\n");
 207         ir_up = true;
 208 }
 209 EXPORT_SYMBOL(ptlrpc_pinger_ir_up);
 210
 211 void ptlrpc_pinger_ir_down(void)
 212 {
 213         CDEBUG(D_HA, "IR down\n");
 214         ir_up = false;
 215 }
 216 EXPORT_SYMBOL(ptlrpc_pinger_ir_down);
 217
 218 static void ptlrpc_pinger_process_import(struct obd_import *imp,
 219                                          time64_t this_ping)
 220 {
 221         int level;
 222         int force;
 223         int force_next;
 224         int suppress;
 225
 226         spin_lock(&imp->imp_lock);
 227
 228         level = imp->imp_state;
 229         force = imp->imp_force_verify;
 230         force_next = imp->imp_force_next_verify;
 231         /*
 232          * This will be used below only if the import is "FULL".
 233          */
 234         suppress = ir_up && OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS);
 235
 236         imp->imp_force_verify = 0;
 237
 238         if (imp->imp_next_ping - 5 >= this_ping && !force) {
 239                 spin_unlock(&imp->imp_lock);
 240                 return;
 241         }
 242
 243         imp->imp_force_next_verify = 0;
 244
 245         CDEBUG(level == LUSTRE_IMP_FULL ? D_INFO : D_HA,
 246                "%s->%s: level %s/%u force %u force_next %u deactive %u pingable %u suppress %u\n",
 247                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 248                ptlrpc_import_state_name(level), level, force, force_next,
 249                imp->imp_deactive, imp->imp_pingable, suppress);
 250
 251         if (level == LUSTRE_IMP_DISCON && !imp_is_deactive(imp)) {
 252                 /* wait for a while before trying recovery again */
 253                 imp->imp_next_ping = ptlrpc_next_reconnect(imp);
 254                 spin_unlock(&imp->imp_lock);
 255                 if (!imp->imp_no_pinger_recover ||
 256                     imp->imp_connect_error == -EAGAIN)
 257                         ptlrpc_initiate_recovery(imp);
 258         } else if (level != LUSTRE_IMP_FULL || imp->imp_obd->obd_no_recov ||
 259                    imp_is_deactive(imp)) {
 260                 CDEBUG(D_HA,
 261                        "%s->%s: not pinging (in recovery or recovery disabled: %s)\n",
 262                        imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 263                        ptlrpc_import_state_name(level));
 264                 if (force)
 265                         imp->imp_force_verify = 1;
 266                 spin_unlock(&imp->imp_lock);
 267         } else if ((imp->imp_pingable && !suppress) || force_next || force) {
 268                 spin_unlock(&imp->imp_lock);
 269                 ptlrpc_ping(imp);
 270         } else {
 271                 spin_unlock(&imp->imp_lock);
 272         }
 273 }
 274
 275 static struct workqueue_struct *pinger_wq;
 276 static void ptlrpc_pinger_main(struct work_struct *ws);
 277 static DECLARE_DELAYED_WORK(ping_work, ptlrpc_pinger_main);
 278
 279 static void ptlrpc_pinger_main(struct work_struct *ws)
 280 {
 281         time64_t this_ping = ktime_get_seconds();
 282         time64_t time_to_next_wake;
 283         struct timeout_item *item;
 284         struct obd_import *imp;
 285         struct list_head *iter;
 286
 287         do {
 288                 mutex_lock(&pinger_mutex);
 289                 list_for_each_entry(item, &timeout_list, ti_chain)
 290                         item->ti_cb(item, item->ti_cb_data);
 291
 292                 list_for_each(iter, &pinger_imports) {
 293                         imp = list_entry(iter, struct obd_import,
 294                                          imp_pinger_chain);
 295
 296                         ptlrpc_pinger_process_import(imp, this_ping);
 297                         /* obd_timeout might have changed */
 298                         if (imp->imp_pingable && imp->imp_next_ping &&
 299                             imp->imp_next_ping > this_ping + PING_INTERVAL)
 300                                 ptlrpc_update_next_ping(imp, 0);
 301                 }
 302                 mutex_unlock(&pinger_mutex);
 303                 /* update memory usage info */
 304                 obd_update_maxusage();
 305
 306                 /* Wait until the next ping time, or until we're stopped. */
 307                 time_to_next_wake = pinger_check_timeout(this_ping);
 308                 /*
 309                  * The ping sent by ptlrpc_send_rpc may get sent out
 310                  * say .01 second after this.
 311                  * ptlrpc_pinger_sending_on_import will then set the
 312                  * next ping time to next_ping + .01 sec, which means
 313                  * we will SKIP the next ping at next_ping, and the
 314                  * ping will get sent 2 timeouts from now!  Beware.
 315                  */
 316                 CDEBUG(D_INFO, "next wakeup in %lld (%lld)\n",
 317                        time_to_next_wake, this_ping + PING_INTERVAL);
 318         } while (time_to_next_wake <= 0);
 319
 320         queue_delayed_work(pinger_wq, &ping_work,
 321                            cfs_time_seconds(max(time_to_next_wake, 1LL)));
 322 }
 323
 324 int ptlrpc_start_pinger(void)
 325 {
 326 #ifdef ENABLE_PINGER
 327         if (pinger_wq)
 328                 return -EALREADY;
 329
 330         pinger_wq = alloc_workqueue("ptlrpc_pinger", 0, 1);
 331         if (!pinger_wq) {
 332                 CERROR("cannot start pinger workqueue\n");
 333                 return -ENOMEM;
 334         }
 335
 336         queue_delayed_work(pinger_wq, &ping_work, 0);
 337
 338         if (suppress_pings)
 339                 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");
 340 #endif
 341         return 0;
 342 }
 343
 344 int ptlrpc_pinger_remove_timeouts(void);
 345
 346 int ptlrpc_stop_pinger(void)
 347 {
 348 #ifdef ENABLE_PINGER
 349         if (!pinger_wq)
 350                 return -EALREADY;
 351
 352         ptlrpc_pinger_remove_timeouts();
 353
 354         cancel_delayed_work_sync(&ping_work);
 355         destroy_workqueue(pinger_wq);
 356         pinger_wq = NULL;
 357 #endif
 358         return 0;
 359 }
 360
 361 void ptlrpc_pinger_sending_on_import(struct obd_import *imp)
 362 {
 363         ptlrpc_update_next_ping(imp, 0);
 364 }
 365
 366 void ptlrpc_pinger_commit_expected(struct obd_import *imp)
 367 {
 368         ptlrpc_update_next_ping(imp, 1);
 369         assert_spin_locked(&imp->imp_lock);
 370         /*
 371          * Avoid reading stale imp_connect_data.  When not sure if pings are
 372          * expected or not on next connection, we assume they are not and force
 373          * one anyway to guarantee the chance of updating
 374          * imp_peer_committed_transno.
 375          */
 376         if (imp->imp_state != LUSTRE_IMP_FULL ||
 377             OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS))
 378                 imp->imp_force_next_verify = 1;
 379 }
 380
 381 int ptlrpc_pinger_add_import(struct obd_import *imp)
 382 {
 383         ENTRY;
 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         ENTRY;
 407
 408         if (list_empty(&imp->imp_pinger_chain))
 409                 RETURN(-ENOENT);
 410
 411         mutex_lock(&pinger_mutex);
 412         list_del_init(&imp->imp_pinger_chain);
 413         CDEBUG(D_HA, "removing pingable import %s->%s\n",
 414                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 415         /* if we remove from pinger we don't want recovery on this import */
 416         imp->imp_obd->obd_no_recov = 1;
 417         class_import_put(imp);
 418         mutex_unlock(&pinger_mutex);
 419         RETURN(0);
 420 }
 421 EXPORT_SYMBOL(ptlrpc_pinger_del_import);
 422
 423 /**
 424  * Register a timeout callback to the pinger list, and the callback will
 425  * be called when timeout happens.
 426  */
 427 static struct timeout_item *ptlrpc_new_timeout(time64_t time,
 428                                                enum timeout_event event,
 429                                                timeout_cb_t cb, void *data)
 430 {
 431         struct timeout_item *ti;
 432
 433         OBD_ALLOC_PTR(ti);
 434         if (!ti)
 435                 return NULL;
 436
 437         INIT_LIST_HEAD(&ti->ti_obd_list);
 438         INIT_LIST_HEAD(&ti->ti_chain);
 439         ti->ti_timeout = time;
 440         ti->ti_event = event;
 441         ti->ti_cb = cb;
 442         ti->ti_cb_data = data;
 443
 444         return ti;
 445 }
 446
 447 /**
 448  * Register timeout event on the the pinger thread.
 449  * Note: the timeout list is an sorted list with increased timeout value.
 450  */
 451 static struct timeout_item*
 452 ptlrpc_pinger_register_timeout(time64_t time, enum timeout_event event,
 453                                timeout_cb_t cb, void *data)
 454 {
 455         struct timeout_item *item, *tmp;
 456
 457         LASSERT(mutex_is_locked(&pinger_mutex));
 458
 459         list_for_each_entry(item, &timeout_list, ti_chain)
 460                 if (item->ti_event == event)
 461                         goto out;
 462
 463         item = ptlrpc_new_timeout(time, event, cb, data);
 464         if (item) {
 465                 list_for_each_entry_reverse(tmp, &timeout_list, ti_chain) {
 466                         if (tmp->ti_timeout < time) {
 467                                 list_add(&item->ti_chain, &tmp->ti_chain);
 468                                 goto out;
 469                         }
 470                 }
 471                 list_add(&item->ti_chain, &timeout_list);
 472         }
 473 out:
 474         return item;
 475 }
 476
 477 /* Add a client_obd to the timeout event list, when timeout(@time)
 478  * happens, the callback(@cb) will be called.
 479  */
 480 int ptlrpc_add_timeout_client(time64_t time, enum timeout_event event,
 481                               timeout_cb_t cb, void *data,
 482                               struct list_head *obd_list)
 483 {
 484         struct timeout_item *ti;
 485
 486         mutex_lock(&pinger_mutex);
 487         ti = ptlrpc_pinger_register_timeout(time, event, cb, data);
 488         if (!ti) {
 489                 mutex_unlock(&pinger_mutex);
 490                 return -EINVAL;
 491         }
 492         list_add(obd_list, &ti->ti_obd_list);
 493         mutex_unlock(&pinger_mutex);
 494         return 0;
 495 }
 496 EXPORT_SYMBOL(ptlrpc_add_timeout_client);
 497
 498 int ptlrpc_del_timeout_client(struct list_head *obd_list,
 499                               enum timeout_event event)
 500 {
 501         struct timeout_item *ti = NULL, *item;
 502
 503         if (list_empty(obd_list))
 504                 return 0;
 505         mutex_lock(&pinger_mutex);
 506         list_del_init(obd_list);
 507         /**
 508          * If there are no obd attached to the timeout event
 509          * list, remove this timeout event from the pinger
 510          */
 511         list_for_each_entry(item, &timeout_list, ti_chain) {
 512                 if (item->ti_event == event) {
 513                         ti = item;
 514                         break;
 515                 }
 516         }
 517         LASSERTF(ti, "ti is NULL !\n");
 518         if (list_empty(&ti->ti_obd_list)) {
 519                 list_del(&ti->ti_chain);
 520                 OBD_FREE_PTR(ti);
 521         }
 522         mutex_unlock(&pinger_mutex);
 523         return 0;
 524 }
 525 EXPORT_SYMBOL(ptlrpc_del_timeout_client);
 526
 527 int ptlrpc_pinger_remove_timeouts(void)
 528 {
 529         struct timeout_item *item, *tmp;
 530
 531         mutex_lock(&pinger_mutex);
 532         list_for_each_entry_safe(item, tmp, &timeout_list, ti_chain) {
 533                 LASSERT(list_empty(&item->ti_obd_list));
 534                 list_del(&item->ti_chain);
 535                 OBD_FREE_PTR(item);
 536         }
 537         mutex_unlock(&pinger_mutex);
 538         return 0;
 539 }
 540
 541 void ptlrpc_pinger_wake_up(void)
 542 {
 543 #ifdef ENABLE_PINGER
 544         mod_delayed_work(pinger_wq, &ping_work, 0);
 545 #endif
 546 }
 547
 548 /* Ping evictor thread */
 549 #define PET_READY     1
 550 #define PET_TERMINATE 2
 551
 552 static int pet_refcount;
 553 static int pet_state;
 554 static wait_queue_head_t pet_waitq;
 555 static struct list_head pet_list;
 556 static DEFINE_SPINLOCK(pet_lock);
 557
 558 int ping_evictor_wake(struct obd_export *exp)
 559 {
 560         struct obd_device *obd;
 561
 562         spin_lock(&pet_lock);
 563         if (pet_state != PET_READY) {
 564                 /* eventually the new obd will call here again. */
 565                 spin_unlock(&pet_lock);
 566                 return 1;
 567         }
 568
 569         obd = class_exp2obd(exp);
 570         if (list_empty(&obd->obd_evict_list)) {
 571                 class_incref(obd, "evictor", obd);
 572                 list_add(&obd->obd_evict_list, &pet_list);
 573         }
 574         spin_unlock(&pet_lock);
 575
 576         wake_up(&pet_waitq);
 577         return 0;
 578 }
 579
 580 static int ping_evictor_main(void *arg)
 581 {
 582         struct obd_device *obd;
 583         struct obd_export *exp;
 584         time64_t expire_time;
 585
 586         ENTRY;
 587         unshare_fs_struct();
 588
 589         CDEBUG(D_HA, "Starting Ping Evictor\n");
 590         pet_state = PET_READY;
 591         while (1) {
 592                 wait_event_idle(pet_waitq,
 593                                 (!list_empty(&pet_list)) ||
 594                                 (pet_state == PET_TERMINATE));
 595
 596                 /* loop until all obd's will be removed */
 597                 if ((pet_state == PET_TERMINATE) && list_empty(&pet_list))
 598                         break;
 599
 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                  */
 605                 spin_lock(&pet_lock);
 606                 obd = list_entry(pet_list.next, struct obd_device,
 607                                  obd_evict_list);
 608                 spin_unlock(&pet_lock);
 609
 610                 expire_time = ktime_get_real_seconds() - PING_EVICT_TIMEOUT;
 611
 612                 CDEBUG(D_HA, "evicting all exports of obd %s older than %lld\n",
 613                        obd->obd_name, expire_time);
 614
 615                 /*
 616                  * Exports can't be deleted out of the list while we hold
 617                  * the obd lock (class_unlink_export), which means we can't
 618                  * lose the last ref on the export.  If they've already been
 619                  * removed from the list, we won't find them here.
 620                  */
 621                 spin_lock(&obd->obd_dev_lock);
 622                 while (!list_empty(&obd->obd_exports_timed)) {
 623                         exp = list_entry(obd->obd_exports_timed.next,
 624                                          struct obd_export,
 625                                          exp_obd_chain_timed);
 626                         if (expire_time > exp->exp_last_request_time) {
 627                                 struct obd_uuid *client_uuid;
 628
 629                                 class_export_get(exp);
 630                                 client_uuid = &exp->exp_client_uuid;
 631                                 spin_unlock(&obd->obd_dev_lock);
 632                                 LCONSOLE_WARN("%s: haven't heard from client %s (at %s) in %lld seconds. I think it's dead, and I am evicting it. exp %p, cur %lld expire %lld last %lld\n",
 633                                               obd->obd_name,
 634                                               obd_uuid2str(client_uuid),
 635                                               obd_export_nid2str(exp),
 636                                               ktime_get_real_seconds() -
 637                                               exp->exp_last_request_time,
 638                                               exp, ktime_get_real_seconds(),
 639                                               expire_time,
 640                                               exp->exp_last_request_time);
 641                                 CDEBUG(D_HA, "Last request was at %lld\n",
 642                                        exp->exp_last_request_time);
 643                                 class_fail_export(exp);
 644                                 class_export_put(exp);
 645                                 spin_lock(&obd->obd_dev_lock);
 646                         } else {
 647                                 /* List is sorted, so everyone below is ok */
 648                                 break;
 649                         }
 650                 }
 651                 spin_unlock(&obd->obd_dev_lock);
 652
 653                 spin_lock(&pet_lock);
 654                 list_del_init(&obd->obd_evict_list);
 655                 spin_unlock(&pet_lock);
 656
 657                 class_decref(obd, "evictor", obd);
 658         }
 659         CDEBUG(D_HA, "Exiting Ping Evictor\n");
 660
 661         RETURN(0);
 662 }
 663
 664 void ping_evictor_start(void)
 665 {
 666         struct task_struct *task;
 667
 668         if (++pet_refcount > 1)
 669                 return;
 670
 671         INIT_LIST_HEAD(&pet_list);
 672         init_waitqueue_head(&pet_waitq);
 673
 674         task = kthread_run(ping_evictor_main, NULL, "ll_evictor");
 675         if (IS_ERR(task)) {
 676                 pet_refcount--;
 677                 CERROR("Cannot start ping evictor thread: %ld\n",
 678                         PTR_ERR(task));
 679         }
 680 }
 681 EXPORT_SYMBOL(ping_evictor_start);
 682
 683 void ping_evictor_stop(void)
 684 {
 685         if (--pet_refcount > 0)
 686                 return;
 687
 688         pet_state = PET_TERMINATE;
 689         wake_up(&pet_waitq);
 690 }
 691 EXPORT_SYMBOL(ping_evictor_stop);