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()
  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         ENTRY;
  80
  81         req = ptlrpc_prep_ping(obd->u.cli.cl_import);
  82         if (req == NULL)
  83                 RETURN(-ENOMEM);
  84
  85         req->rq_send_state = LUSTRE_IMP_FULL;
  86
  87         rc = ptlrpc_queue_wait(req);
  88
  89         ptlrpc_req_finished(req);
  90
  91         RETURN(rc);
  92 }
  93 EXPORT_SYMBOL(ptlrpc_obd_ping);
  94
  95 static bool ptlrpc_check_import_is_idle(struct obd_import *imp)
  96 {
  97         struct ldlm_namespace *ns = imp->imp_obd->obd_namespace;
  98         time64_t now;
  99
 100         if (!imp->imp_idle_timeout)
 101                 return false;
 102
 103         /* 4 comes from:
 104          *  - client_obd_setup() - hashed import
 105          *  - ptlrpcd_alloc_work()
 106          *  - ptlrpcd_alloc_work()
 107          *  - ptlrpc_pinger_add_import
 108          */
 109         if (atomic_read(&imp->imp_refcount) > 4)
 110                 return false;
 111
 112         /* any lock increases ns_bref being a resource holder */
 113         if (ns && atomic_read(&ns->ns_bref) > 0)
 114                 return false;
 115
 116         now = ktime_get_real_seconds();
 117         if (now - imp->imp_last_reply_time < imp->imp_idle_timeout)
 118                 return false;
 119
 120         return true;
 121 }
 122
 123 static int ptlrpc_ping(struct obd_import *imp)
 124 {
 125         struct ptlrpc_request   *req;
 126         ENTRY;
 127
 128         if (ptlrpc_check_import_is_idle(imp))
 129                 RETURN(ptlrpc_disconnect_and_idle_import(imp));
 130
 131         req = ptlrpc_prep_ping(imp);
 132         if (req == NULL) {
 133                 CERROR("OOM trying to ping %s->%s\n",
 134                        imp->imp_obd->obd_uuid.uuid,
 135                        obd2cli_tgt(imp->imp_obd));
 136                 RETURN(-ENOMEM);
 137         }
 138
 139         DEBUG_REQ(D_INFO, req, "pinging %s->%s",
 140                   imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 141         ptlrpcd_add_req(req);
 142
 143         RETURN(0);
 144 }
 145
 146 static void ptlrpc_update_next_ping(struct obd_import *imp, int soon)
 147 {
 148 #ifdef ENABLE_PINGER
 149         time64_t time = soon ? PING_INTERVAL_SHORT : PING_INTERVAL;
 150
 151         if (imp->imp_state == LUSTRE_IMP_DISCON) {
 152                 time64_t dtime = max_t(time64_t, CONNECTION_SWITCH_MIN,
 153                                        AT_OFF ? 0 :
 154                                        at_get(&imp->imp_at.iat_net_latency));
 155                 time = min(time, dtime);
 156         }
 157         imp->imp_next_ping = ktime_get_seconds() + time;
 158 #endif /* ENABLE_PINGER */
 159 }
 160
 161 void ptlrpc_ping_import_soon(struct obd_import *imp)
 162 {
 163         imp->imp_next_ping = ktime_get_seconds();
 164 }
 165
 166 static inline int imp_is_deactive(struct obd_import *imp)
 167 {
 168         return (imp->imp_deactive ||
 169                 OBD_FAIL_CHECK(OBD_FAIL_PTLRPC_IMP_DEACTIVE));
 170 }
 171
 172 static inline time64_t ptlrpc_next_reconnect(struct obd_import *imp)
 173 {
 174         if (imp->imp_server_timeout)
 175                 return ktime_get_seconds() + (obd_timeout >> 1);
 176         else
 177                 return ktime_get_seconds() + obd_timeout;
 178 }
 179
 180 static time64_t pinger_check_timeout(time64_t time)
 181 {
 182         struct timeout_item *item;
 183         time64_t timeout = PING_INTERVAL;
 184
 185         /* This list is sorted in increasing timeout order */
 186         mutex_lock(&pinger_mutex);
 187         list_for_each_entry(item, &timeout_list, ti_chain) {
 188                 time64_t ti_timeout = item->ti_timeout;
 189
 190                 if (timeout > ti_timeout)
 191                         timeout = ti_timeout;
 192                 break;
 193         }
 194         mutex_unlock(&pinger_mutex);
 195
 196         return time + timeout - ktime_get_seconds();
 197 }
 198
 199 static bool ir_up;
 200
 201 void ptlrpc_pinger_ir_up(void)
 202 {
 203         CDEBUG(D_HA, "IR up\n");
 204         ir_up = true;
 205 }
 206 EXPORT_SYMBOL(ptlrpc_pinger_ir_up);
 207
 208 void ptlrpc_pinger_ir_down(void)
 209 {
 210         CDEBUG(D_HA, "IR down\n");
 211         ir_up = false;
 212 }
 213 EXPORT_SYMBOL(ptlrpc_pinger_ir_down);
 214
 215 static void ptlrpc_pinger_process_import(struct obd_import *imp,
 216                                          time64_t this_ping)
 217 {
 218         int level;
 219         int force;
 220         int force_next;
 221         int suppress;
 222
 223         spin_lock(&imp->imp_lock);
 224
 225         level = imp->imp_state;
 226         force = imp->imp_force_verify;
 227         force_next = imp->imp_force_next_verify;
 228         /*
 229          * This will be used below only if the import is "FULL".
 230          */
 231         suppress = ir_up && OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS);
 232
 233         imp->imp_force_verify = 0;
 234
 235         if (imp->imp_next_ping - 5 >= this_ping && !force) {
 236                 spin_unlock(&imp->imp_lock);
 237                 return;
 238         }
 239
 240         imp->imp_force_next_verify = 0;
 241
 242         spin_unlock(&imp->imp_lock);
 243
 244         CDEBUG(level == LUSTRE_IMP_FULL ? D_INFO : D_HA, "%s->%s: level %s/%u "
 245                "force %u force_next %u deactive %u pingable %u suppress %u\n",
 246                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 247                ptlrpc_import_state_name(level), level, force, force_next,
 248                imp->imp_deactive, imp->imp_pingable, suppress);
 249
 250         if (level == LUSTRE_IMP_DISCON && !imp_is_deactive(imp)) {
 251                 /* wait for a while before trying recovery again */
 252                 imp->imp_next_ping = ptlrpc_next_reconnect(imp);
 253                 if (!imp->imp_no_pinger_recover)
 254                         ptlrpc_initiate_recovery(imp);
 255         } else if (level != LUSTRE_IMP_FULL ||
 256                    imp->imp_obd->obd_no_recov ||
 257                    imp_is_deactive(imp)) {
 258                 CDEBUG(D_HA, "%s->%s: not pinging (in recovery "
 259                        "or recovery disabled: %s)\n",
 260                        imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 261                        ptlrpc_import_state_name(level));
 262                 if (force) {
 263                         spin_lock(&imp->imp_lock);
 264                         imp->imp_force_verify = 1;
 265                         spin_unlock(&imp->imp_lock);
 266                 }
 267         } else if ((imp->imp_pingable && !suppress) || force_next || force) {
 268                 ptlrpc_ping(imp);
 269         }
 270 }
 271
 272 static struct workqueue_struct *pinger_wq;
 273 static void ptlrpc_pinger_main(struct work_struct *ws);
 274 static DECLARE_DELAYED_WORK(ping_work, ptlrpc_pinger_main);
 275
 276 static void ptlrpc_pinger_main(struct work_struct *ws)
 277 {
 278         time64_t this_ping = ktime_get_seconds();
 279         time64_t time_to_next_wake;
 280         struct timeout_item *item;
 281         struct obd_import *imp;
 282         struct list_head *iter;
 283
 284         do {
 285                 mutex_lock(&pinger_mutex);
 286                 list_for_each_entry(item, &timeout_list, ti_chain)
 287                         item->ti_cb(item, item->ti_cb_data);
 288
 289                 list_for_each(iter, &pinger_imports) {
 290                         imp = list_entry(iter, struct obd_import,
 291                                          imp_pinger_chain);
 292
 293                         ptlrpc_pinger_process_import(imp, this_ping);
 294                         /* obd_timeout might have changed */
 295                         if (imp->imp_pingable && imp->imp_next_ping &&
 296                             imp->imp_next_ping > this_ping + PING_INTERVAL)
 297                                 ptlrpc_update_next_ping(imp, 0);
 298                 }
 299                 mutex_unlock(&pinger_mutex);
 300                 /* update memory usage info */
 301                 obd_update_maxusage();
 302
 303                 /* Wait until the next ping time, or until we're stopped. */
 304                 time_to_next_wake = pinger_check_timeout(this_ping);
 305                 /* The ping sent by ptlrpc_send_rpc may get sent out
 306                  * say .01 second after this.
 307                  * ptlrpc_pinger_sending_on_import will then set the
 308                  * next ping time to next_ping + .01 sec, which means
 309                  * we will SKIP the next ping at next_ping, and the
 310                  * ping will get sent 2 timeouts from now!  Beware. */
 311                 CDEBUG(D_INFO, "next wakeup in %lld (%lld)\n",
 312                        time_to_next_wake, this_ping + PING_INTERVAL);
 313         } while (time_to_next_wake <= 0);
 314
 315         queue_delayed_work(pinger_wq, &ping_work,
 316                            cfs_time_seconds(max(time_to_next_wake, 1LL)));
 317 }
 318
 319 int ptlrpc_start_pinger(void)
 320 {
 321 #ifdef ENABLE_PINGER
 322         if (pinger_wq)
 323                 return -EALREADY;
 324
 325         pinger_wq = alloc_workqueue("ptlrpc_pinger", 0, 1);
 326         if (!pinger_wq) {
 327                 CERROR("cannot start pinger workqueue\n");
 328                 return -ENOMEM;
 329         }
 330
 331         queue_delayed_work(pinger_wq, &ping_work, 0);
 332
 333         if (suppress_pings)
 334                 CWARN("Pings will be suppressed at the request of the "
 335                       "administrator.  The configuration shall meet the "
 336                       "additional requirements described in the manual.  "
 337                       "(Search for the \"suppress_pings\" kernel module "
 338                       "parameter.)\n");
 339 #endif
 340         return 0;
 341 }
 342
 343 int ptlrpc_pinger_remove_timeouts(void);
 344
 345 int ptlrpc_stop_pinger(void)
 346 {
 347 #ifdef ENABLE_PINGER
 348         if (!pinger_wq)
 349                 return -EALREADY;
 350
 351         ptlrpc_pinger_remove_timeouts();
 352
 353         cancel_delayed_work_sync(&ping_work);
 354         destroy_workqueue(pinger_wq);
 355         pinger_wq = NULL;
 356 #endif
 357         return 0;
 358 }
 359
 360 void ptlrpc_pinger_sending_on_import(struct obd_import *imp)
 361 {
 362         ptlrpc_update_next_ping(imp, 0);
 363 }
 364
 365 void ptlrpc_pinger_commit_expected(struct obd_import *imp)
 366 {
 367         ptlrpc_update_next_ping(imp, 1);
 368         assert_spin_locked(&imp->imp_lock);
 369         /*
 370          * Avoid reading stale imp_connect_data.  When not sure if pings are
 371          * expected or not on next connection, we assume they are not and force
 372          * one anyway to guarantee the chance of updating
 373          * imp_peer_committed_transno.
 374          */
 375         if (imp->imp_state != LUSTRE_IMP_FULL ||
 376             OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS))
 377                 imp->imp_force_next_verify = 1;
 378 }
 379
 380 int ptlrpc_pinger_add_import(struct obd_import *imp)
 381 {
 382         ENTRY;
 383         if (!list_empty(&imp->imp_pinger_chain))
 384                 RETURN(-EALREADY);
 385
 386         mutex_lock(&pinger_mutex);
 387         CDEBUG(D_HA, "adding pingable import %s->%s\n",
 388                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 389         /* if we add to pinger we want recovery on this import */
 390         imp->imp_obd->obd_no_recov = 0;
 391         ptlrpc_update_next_ping(imp, 0);
 392         /* XXX sort, blah blah */
 393         list_add_tail(&imp->imp_pinger_chain, &pinger_imports);
 394         class_import_get(imp);
 395
 396         ptlrpc_pinger_wake_up();
 397         mutex_unlock(&pinger_mutex);
 398
 399         RETURN(0);
 400 }
 401 EXPORT_SYMBOL(ptlrpc_pinger_add_import);
 402
 403 int ptlrpc_pinger_del_import(struct obd_import *imp)
 404 {
 405         ENTRY;
 406
 407         if (list_empty(&imp->imp_pinger_chain))
 408                 RETURN(-ENOENT);
 409
 410         mutex_lock(&pinger_mutex);
 411         list_del_init(&imp->imp_pinger_chain);
 412         CDEBUG(D_HA, "removing pingable import %s->%s\n",
 413                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 414         /* if we remove from pinger we don't want recovery on this import */
 415         imp->imp_obd->obd_no_recov = 1;
 416         class_import_put(imp);
 417         mutex_unlock(&pinger_mutex);
 418         RETURN(0);
 419 }
 420 EXPORT_SYMBOL(ptlrpc_pinger_del_import);
 421
 422 /**
 423  * Register a timeout callback to the pinger list, and the callback will
 424  * be called when timeout happens.
 425  */
 426 static struct timeout_item *ptlrpc_new_timeout(time64_t time,
 427                                                enum timeout_event event,
 428                                                timeout_cb_t cb, void *data)
 429 {
 430         struct timeout_item *ti;
 431
 432         OBD_ALLOC_PTR(ti);
 433         if (!ti)
 434                 return(NULL);
 435
 436         INIT_LIST_HEAD(&ti->ti_obd_list);
 437         INIT_LIST_HEAD(&ti->ti_chain);
 438         ti->ti_timeout = time;
 439         ti->ti_event = event;
 440         ti->ti_cb = cb;
 441         ti->ti_cb_data = data;
 442
 443         return ti;
 444 }
 445
 446 /**
 447  * Register timeout event on the the pinger thread.
 448  * Note: the timeout list is an sorted list with increased timeout value.
 449  */
 450 static struct timeout_item*
 451 ptlrpc_pinger_register_timeout(time64_t time, enum timeout_event event,
 452                                timeout_cb_t cb, void *data)
 453 {
 454         struct timeout_item *item, *tmp;
 455
 456         LASSERT(mutex_is_locked(&pinger_mutex));
 457
 458         list_for_each_entry(item, &timeout_list, ti_chain)
 459                 if (item->ti_event == event)
 460                         goto out;
 461
 462         item = ptlrpc_new_timeout(time, event, cb, data);
 463         if (item) {
 464                 list_for_each_entry_reverse(tmp, &timeout_list, ti_chain) {
 465                         if (tmp->ti_timeout < time) {
 466                                 list_add(&item->ti_chain, &tmp->ti_chain);
 467                                 goto out;
 468                         }
 469                 }
 470                 list_add(&item->ti_chain, &timeout_list);
 471         }
 472 out:
 473         return item;
 474 }
 475
 476 /* Add a client_obd to the timeout event list, when timeout(@time)
 477  * happens, the callback(@cb) will be called.
 478  */
 479 int ptlrpc_add_timeout_client(time64_t time, enum timeout_event event,
 480                               timeout_cb_t cb, void *data,
 481                               struct list_head *obd_list)
 482 {
 483         struct timeout_item *ti;
 484
 485         mutex_lock(&pinger_mutex);
 486         ti = ptlrpc_pinger_register_timeout(time, event, cb, data);
 487         if (!ti) {
 488                 mutex_unlock(&pinger_mutex);
 489                 return (-EINVAL);
 490         }
 491         list_add(obd_list, &ti->ti_obd_list);
 492         mutex_unlock(&pinger_mutex);
 493         return 0;
 494 }
 495 EXPORT_SYMBOL(ptlrpc_add_timeout_client);
 496
 497 int ptlrpc_del_timeout_client(struct list_head *obd_list,
 498                               enum timeout_event event)
 499 {
 500         struct timeout_item *ti = NULL, *item;
 501
 502         if (list_empty(obd_list))
 503                 return 0;
 504         mutex_lock(&pinger_mutex);
 505         list_del_init(obd_list);
 506         /**
 507          * If there are no obd attached to the timeout event
 508          * list, remove this timeout event from the pinger
 509          */
 510         list_for_each_entry(item, &timeout_list, ti_chain) {
 511                 if (item->ti_event == event) {
 512                         ti = item;
 513                         break;
 514                 }
 515         }
 516         LASSERTF(ti != NULL, "ti is NULL !\n");
 517         if (list_empty(&ti->ti_obd_list)) {
 518                 list_del(&ti->ti_chain);
 519                 OBD_FREE_PTR(ti);
 520         }
 521         mutex_unlock(&pinger_mutex);
 522         return 0;
 523 }
 524 EXPORT_SYMBOL(ptlrpc_del_timeout_client);
 525
 526 int ptlrpc_pinger_remove_timeouts(void)
 527 {
 528         struct timeout_item *item, *tmp;
 529
 530         mutex_lock(&pinger_mutex);
 531         list_for_each_entry_safe(item, tmp, &timeout_list, ti_chain) {
 532                 LASSERT(list_empty(&item->ti_obd_list));
 533                 list_del(&item->ti_chain);
 534                 OBD_FREE_PTR(item);
 535         }
 536         mutex_unlock(&pinger_mutex);
 537         return 0;
 538 }
 539
 540 void ptlrpc_pinger_wake_up()
 541 {
 542 #ifdef ENABLE_PINGER
 543         mod_delayed_work(pinger_wq, &ping_work, 0);
 544 #endif
 545 }
 546
 547 /* Ping evictor thread */
 548 #define PET_READY     1
 549 #define PET_TERMINATE 2
 550
 551 static int               pet_refcount = 0;
 552 static int               pet_state;
 553 static wait_queue_head_t pet_waitq;
 554 static struct list_head  pet_list;
 555 static DEFINE_SPINLOCK(pet_lock);
 556
 557 int ping_evictor_wake(struct obd_export *exp)
 558 {
 559         struct obd_device *obd;
 560
 561         spin_lock(&pet_lock);
 562         if (pet_state != PET_READY) {
 563                 /* eventually the new obd will call here again. */
 564                 spin_unlock(&pet_lock);
 565                 return 1;
 566         }
 567
 568         obd = class_exp2obd(exp);
 569         if (list_empty(&obd->obd_evict_list)) {
 570                 class_incref(obd, "evictor", obd);
 571                 list_add(&obd->obd_evict_list, &pet_list);
 572         }
 573         spin_unlock(&pet_lock);
 574
 575         wake_up(&pet_waitq);
 576         return 0;
 577 }
 578
 579 static int ping_evictor_main(void *arg)
 580 {
 581         struct obd_device *obd;
 582         struct obd_export *exp;
 583         struct l_wait_info lwi = { 0 };
 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                 l_wait_event(pet_waitq, (!list_empty(&pet_list)) ||
 593                             (pet_state == PET_TERMINATE), &lwi);
 594
 595                 /* loop until all obd's will be removed */
 596                 if ((pet_state == PET_TERMINATE) && list_empty(&pet_list))
 597                         break;
 598
 599                 /* we only get here if pet_exp != NULL, and the end of this
 600                  * loop is the only place which sets it NULL again, so lock
 601                  * is not strictly necessary. */
 602                 spin_lock(&pet_lock);
 603                 obd = list_entry(pet_list.next, struct obd_device,
 604                                  obd_evict_list);
 605                 spin_unlock(&pet_lock);
 606
 607                 expire_time = ktime_get_real_seconds() - PING_EVICT_TIMEOUT;
 608
 609                 CDEBUG(D_HA, "evicting all exports of obd %s older than %lld\n",
 610                        obd->obd_name, expire_time);
 611
 612                 /* Exports can't be deleted out of the list while we hold
 613                  * the obd lock (class_unlink_export), which means we can't
 614                  * lose the last ref on the export.  If they've already been
 615                  * removed from the list, we won't find them here. */
 616                 spin_lock(&obd->obd_dev_lock);
 617                 while (!list_empty(&obd->obd_exports_timed)) {
 618                         exp = list_entry(obd->obd_exports_timed.next,
 619                                          struct obd_export,
 620                                          exp_obd_chain_timed);
 621                         if (expire_time > exp->exp_last_request_time) {
 622                                 class_export_get(exp);
 623                                 spin_unlock(&obd->obd_dev_lock);
 624                                 LCONSOLE_WARN("%s: haven't heard from client %s"
 625                                               " (at %s) in %lld seconds. I think"
 626                                               " it's dead, and I am evicting"
 627                                               " it. exp %p, cur %lld expire %lld"
 628                                               " last %lld\n",
 629                                               obd->obd_name,
 630                                               obd_uuid2str(&exp->exp_client_uuid),
 631                                               obd_export_nid2str(exp),
 632                                               ktime_get_real_seconds() -
 633                                               exp->exp_last_request_time,
 634                                               exp, ktime_get_real_seconds(),
 635                                               expire_time,
 636                                               exp->exp_last_request_time);
 637                                 CDEBUG(D_HA, "Last request was at %lld\n",
 638                                        exp->exp_last_request_time);
 639                                 class_fail_export(exp);
 640                                 class_export_put(exp);
 641                                 spin_lock(&obd->obd_dev_lock);
 642                         } else {
 643                                 /* List is sorted, so everyone below is ok */
 644                                 break;
 645                         }
 646                 }
 647                 spin_unlock(&obd->obd_dev_lock);
 648
 649                 spin_lock(&pet_lock);
 650                 list_del_init(&obd->obd_evict_list);
 651                 spin_unlock(&pet_lock);
 652
 653                 class_decref(obd, "evictor", obd);
 654         }
 655         CDEBUG(D_HA, "Exiting Ping Evictor\n");
 656
 657         RETURN(0);
 658 }
 659
 660 void ping_evictor_start(void)
 661 {
 662         struct task_struct *task;
 663
 664         if (++pet_refcount > 1)
 665                 return;
 666
 667         INIT_LIST_HEAD(&pet_list);
 668         init_waitqueue_head(&pet_waitq);
 669
 670         task = kthread_run(ping_evictor_main, NULL, "ll_evictor");
 671         if (IS_ERR(task)) {
 672                 pet_refcount--;
 673                 CERROR("Cannot start ping evictor thread: %ld\n",
 674                         PTR_ERR(task));
 675         }
 676 }
 677 EXPORT_SYMBOL(ping_evictor_start);
 678
 679 void ping_evictor_stop(void)
 680 {
 681         if (--pet_refcount > 0)
 682                 return;
 683
 684         pet_state = PET_TERMINATE;
 685         wake_up(&pet_waitq);
 686 }
 687 EXPORT_SYMBOL(ping_evictor_stop);