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         /* 4 comes from:
 103          *  - client_obd_setup() - hashed import
 104          *  - ptlrpcd_alloc_work()
 105          *  - ptlrpcd_alloc_work()
 106          *  - ptlrpc_pinger_add_import
 107          */
 108         if (atomic_read(&imp->imp_refcount) > 4)
 109                 return false;
 110         /* any lock increases ns_bref being a resource holder */
 111         if (ns && atomic_read(&ns->ns_bref) > 0)
 112                 return false;
 113
 114         now = ktime_get_real_seconds();
 115         if (now - imp->imp_last_reply_time < imp->imp_idle_timeout)
 116                 return false;
 117
 118         return true;
 119 }
 120
 121 static int ptlrpc_ping(struct obd_import *imp)
 122 {
 123         struct ptlrpc_request   *req;
 124         ENTRY;
 125
 126         if (ptlrpc_check_import_is_idle(imp))
 127                 RETURN(ptlrpc_disconnect_and_idle_import(imp));
 128
 129         req = ptlrpc_prep_ping(imp);
 130         if (req == NULL) {
 131                 CERROR("OOM trying to ping %s->%s\n",
 132                        imp->imp_obd->obd_uuid.uuid,
 133                        obd2cli_tgt(imp->imp_obd));
 134                 RETURN(-ENOMEM);
 135         }
 136
 137         DEBUG_REQ(D_INFO, req, "pinging %s->%s",
 138                   imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 139         ptlrpcd_add_req(req);
 140
 141         RETURN(0);
 142 }
 143
 144 static void ptlrpc_update_next_ping(struct obd_import *imp, int soon)
 145 {
 146 #ifdef ENABLE_PINGER
 147         time64_t time = soon ? PING_INTERVAL_SHORT : PING_INTERVAL;
 148
 149         if (imp->imp_state == LUSTRE_IMP_DISCON) {
 150                 time64_t dtime = max_t(time64_t, CONNECTION_SWITCH_MIN,
 151                                        AT_OFF ? 0 :
 152                                        at_get(&imp->imp_at.iat_net_latency));
 153                 time = min(time, dtime);
 154         }
 155         imp->imp_next_ping = ktime_get_seconds() + time;
 156 #endif /* ENABLE_PINGER */
 157 }
 158
 159 void ptlrpc_ping_import_soon(struct obd_import *imp)
 160 {
 161         imp->imp_next_ping = ktime_get_seconds();
 162 }
 163
 164 static inline int imp_is_deactive(struct obd_import *imp)
 165 {
 166         return (imp->imp_deactive ||
 167                 OBD_FAIL_CHECK(OBD_FAIL_PTLRPC_IMP_DEACTIVE));
 168 }
 169
 170 static inline time64_t ptlrpc_next_reconnect(struct obd_import *imp)
 171 {
 172         if (imp->imp_server_timeout)
 173                 return ktime_get_seconds() + (obd_timeout >> 1);
 174         else
 175                 return ktime_get_seconds() + obd_timeout;
 176 }
 177
 178 static time64_t pinger_check_timeout(time64_t time)
 179 {
 180         struct timeout_item *item;
 181         time64_t timeout = PING_INTERVAL;
 182
 183         /* This list is sorted in increasing timeout order */
 184         mutex_lock(&pinger_mutex);
 185         list_for_each_entry(item, &timeout_list, ti_chain) {
 186                 time64_t ti_timeout = item->ti_timeout;
 187
 188                 if (timeout > ti_timeout)
 189                         timeout = ti_timeout;
 190                 break;
 191         }
 192         mutex_unlock(&pinger_mutex);
 193
 194         return time + timeout - ktime_get_seconds();
 195 }
 196
 197 static bool ir_up;
 198
 199 void ptlrpc_pinger_ir_up(void)
 200 {
 201         CDEBUG(D_HA, "IR up\n");
 202         ir_up = true;
 203 }
 204 EXPORT_SYMBOL(ptlrpc_pinger_ir_up);
 205
 206 void ptlrpc_pinger_ir_down(void)
 207 {
 208         CDEBUG(D_HA, "IR down\n");
 209         ir_up = false;
 210 }
 211 EXPORT_SYMBOL(ptlrpc_pinger_ir_down);
 212
 213 static void ptlrpc_pinger_process_import(struct obd_import *imp,
 214                                          time64_t this_ping)
 215 {
 216         int level;
 217         int force;
 218         int force_next;
 219         int suppress;
 220
 221         spin_lock(&imp->imp_lock);
 222
 223         level = imp->imp_state;
 224         force = imp->imp_force_verify;
 225         force_next = imp->imp_force_next_verify;
 226         /*
 227          * This will be used below only if the import is "FULL".
 228          */
 229         suppress = ir_up && OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS);
 230
 231         imp->imp_force_verify = 0;
 232
 233         if (imp->imp_next_ping - 5 >= this_ping && !force) {
 234                 spin_unlock(&imp->imp_lock);
 235                 return;
 236         }
 237
 238         imp->imp_force_next_verify = 0;
 239
 240         spin_unlock(&imp->imp_lock);
 241
 242         CDEBUG(level == LUSTRE_IMP_FULL ? D_INFO : D_HA, "%s->%s: level %s/%u "
 243                "force %u force_next %u deactive %u pingable %u suppress %u\n",
 244                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 245                ptlrpc_import_state_name(level), level, force, force_next,
 246                imp->imp_deactive, imp->imp_pingable, suppress);
 247
 248         if (level == LUSTRE_IMP_DISCON && !imp_is_deactive(imp)) {
 249                 /* wait for a while before trying recovery again */
 250                 imp->imp_next_ping = ptlrpc_next_reconnect(imp);
 251                 if (!imp->imp_no_pinger_recover)
 252                         ptlrpc_initiate_recovery(imp);
 253         } else if (level != LUSTRE_IMP_FULL ||
 254                    imp->imp_obd->obd_no_recov ||
 255                    imp_is_deactive(imp)) {
 256                 CDEBUG(D_HA, "%s->%s: not pinging (in recovery "
 257                        "or recovery disabled: %s)\n",
 258                        imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 259                        ptlrpc_import_state_name(level));
 260                 if (force) {
 261                         spin_lock(&imp->imp_lock);
 262                         imp->imp_force_verify = 1;
 263                         spin_unlock(&imp->imp_lock);
 264                 }
 265         } else if ((imp->imp_pingable && !suppress) || force_next || force) {
 266                 ptlrpc_ping(imp);
 267         }
 268 }
 269
 270 static struct workqueue_struct *pinger_wq;
 271 static void ptlrpc_pinger_main(struct work_struct *ws);
 272 static DECLARE_DELAYED_WORK(ping_work, ptlrpc_pinger_main);
 273
 274 static void ptlrpc_pinger_main(struct work_struct *ws)
 275 {
 276         time64_t this_ping = ktime_get_seconds();
 277         time64_t time_to_next_wake;
 278         struct timeout_item *item;
 279         struct obd_import *imp;
 280         struct list_head *iter;
 281
 282         do {
 283                 mutex_lock(&pinger_mutex);
 284                 list_for_each_entry(item, &timeout_list, ti_chain)
 285                         item->ti_cb(item, item->ti_cb_data);
 286
 287                 list_for_each(iter, &pinger_imports) {
 288                         imp = list_entry(iter, struct obd_import,
 289                                          imp_pinger_chain);
 290
 291                         ptlrpc_pinger_process_import(imp, this_ping);
 292                         /* obd_timeout might have changed */
 293                         if (imp->imp_pingable && imp->imp_next_ping &&
 294                             imp->imp_next_ping > this_ping + PING_INTERVAL)
 295                                 ptlrpc_update_next_ping(imp, 0);
 296                 }
 297                 mutex_unlock(&pinger_mutex);
 298                 /* update memory usage info */
 299                 obd_update_maxusage();
 300
 301                 /* Wait until the next ping time, or until we're stopped. */
 302                 time_to_next_wake = pinger_check_timeout(this_ping);
 303                 /* The ping sent by ptlrpc_send_rpc may get sent out
 304                  * say .01 second after this.
 305                  * ptlrpc_pinger_sending_on_import will then set the
 306                  * next ping time to next_ping + .01 sec, which means
 307                  * we will SKIP the next ping at next_ping, and the
 308                  * ping will get sent 2 timeouts from now!  Beware. */
 309                 CDEBUG(D_INFO, "next wakeup in %lld (%lld)\n",
 310                        time_to_next_wake, this_ping + PING_INTERVAL);
 311         } while (time_to_next_wake <= 0);
 312
 313         queue_delayed_work(pinger_wq, &ping_work,
 314                            cfs_time_seconds(max(time_to_next_wake, 1LL)));
 315 }
 316
 317 int ptlrpc_start_pinger(void)
 318 {
 319 #ifdef ENABLE_PINGER
 320         if (pinger_wq)
 321                 return -EALREADY;
 322
 323         pinger_wq = alloc_workqueue("ptlrpc_pinger", 0, 1);
 324         if (!pinger_wq) {
 325                 CERROR("cannot start pinger workqueue\n");
 326                 return -ENOMEM;
 327         }
 328
 329         queue_delayed_work(pinger_wq, &ping_work, 0);
 330
 331         if (suppress_pings)
 332                 CWARN("Pings will be suppressed at the request of the "
 333                       "administrator.  The configuration shall meet the "
 334                       "additional requirements described in the manual.  "
 335                       "(Search for the \"suppress_pings\" kernel module "
 336                       "parameter.)\n");
 337 #endif
 338         return 0;
 339 }
 340
 341 int ptlrpc_pinger_remove_timeouts(void);
 342
 343 int ptlrpc_stop_pinger(void)
 344 {
 345 #ifdef ENABLE_PINGER
 346         if (!pinger_wq)
 347                 return -EALREADY;
 348
 349         ptlrpc_pinger_remove_timeouts();
 350
 351         cancel_delayed_work_sync(&ping_work);
 352         destroy_workqueue(pinger_wq);
 353         pinger_wq = NULL;
 354 #endif
 355         return 0;
 356 }
 357
 358 void ptlrpc_pinger_sending_on_import(struct obd_import *imp)
 359 {
 360         ptlrpc_update_next_ping(imp, 0);
 361 }
 362
 363 void ptlrpc_pinger_commit_expected(struct obd_import *imp)
 364 {
 365         ptlrpc_update_next_ping(imp, 1);
 366         assert_spin_locked(&imp->imp_lock);
 367         /*
 368          * Avoid reading stale imp_connect_data.  When not sure if pings are
 369          * expected or not on next connection, we assume they are not and force
 370          * one anyway to guarantee the chance of updating
 371          * imp_peer_committed_transno.
 372          */
 373         if (imp->imp_state != LUSTRE_IMP_FULL ||
 374             OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS))
 375                 imp->imp_force_next_verify = 1;
 376 }
 377
 378 int ptlrpc_pinger_add_import(struct obd_import *imp)
 379 {
 380         ENTRY;
 381         if (!list_empty(&imp->imp_pinger_chain))
 382                 RETURN(-EALREADY);
 383
 384         mutex_lock(&pinger_mutex);
 385         CDEBUG(D_HA, "adding pingable import %s->%s\n",
 386                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 387         /* if we add to pinger we want recovery on this import */
 388         imp->imp_obd->obd_no_recov = 0;
 389         ptlrpc_update_next_ping(imp, 0);
 390         /* XXX sort, blah blah */
 391         list_add_tail(&imp->imp_pinger_chain, &pinger_imports);
 392         class_import_get(imp);
 393
 394         ptlrpc_pinger_wake_up();
 395         mutex_unlock(&pinger_mutex);
 396
 397         RETURN(0);
 398 }
 399 EXPORT_SYMBOL(ptlrpc_pinger_add_import);
 400
 401 int ptlrpc_pinger_del_import(struct obd_import *imp)
 402 {
 403         ENTRY;
 404
 405         if (list_empty(&imp->imp_pinger_chain))
 406                 RETURN(-ENOENT);
 407
 408         mutex_lock(&pinger_mutex);
 409         list_del_init(&imp->imp_pinger_chain);
 410         CDEBUG(D_HA, "removing pingable import %s->%s\n",
 411                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 412         /* if we remove from pinger we don't want recovery on this import */
 413         imp->imp_obd->obd_no_recov = 1;
 414         class_import_put(imp);
 415         mutex_unlock(&pinger_mutex);
 416         RETURN(0);
 417 }
 418 EXPORT_SYMBOL(ptlrpc_pinger_del_import);
 419
 420 /**
 421  * Register a timeout callback to the pinger list, and the callback will
 422  * be called when timeout happens.
 423  */
 424 static struct timeout_item *ptlrpc_new_timeout(time64_t time,
 425                                                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 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(time64_t 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(time64_t 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()
 539 {
 540 #ifdef ENABLE_PINGER
 541         mod_delayed_work(pinger_wq, &ping_work, 0);
 542 #endif
 543 }
 544
 545 /* Ping evictor thread */
 546 #define PET_READY     1
 547 #define PET_TERMINATE 2
 548
 549 static int               pet_refcount = 0;
 550 static int               pet_state;
 551 static wait_queue_head_t pet_waitq;
 552 static struct list_head  pet_list;
 553 static DEFINE_SPINLOCK(pet_lock);
 554
 555 int ping_evictor_wake(struct obd_export *exp)
 556 {
 557         struct obd_device *obd;
 558
 559         spin_lock(&pet_lock);
 560         if (pet_state != PET_READY) {
 561                 /* eventually the new obd will call here again. */
 562                 spin_unlock(&pet_lock);
 563                 return 1;
 564         }
 565
 566         obd = class_exp2obd(exp);
 567         if (list_empty(&obd->obd_evict_list)) {
 568                 class_incref(obd, "evictor", obd);
 569                 list_add(&obd->obd_evict_list, &pet_list);
 570         }
 571         spin_unlock(&pet_lock);
 572
 573         wake_up(&pet_waitq);
 574         return 0;
 575 }
 576
 577 static int ping_evictor_main(void *arg)
 578 {
 579         struct obd_device *obd;
 580         struct obd_export *exp;
 581         struct l_wait_info lwi = { 0 };
 582         time64_t expire_time;
 583
 584         ENTRY;
 585         unshare_fs_struct();
 586
 587         CDEBUG(D_HA, "Starting Ping Evictor\n");
 588         pet_state = PET_READY;
 589         while (1) {
 590                 l_wait_event(pet_waitq, (!list_empty(&pet_list)) ||
 591                             (pet_state == PET_TERMINATE), &lwi);
 592
 593                 /* loop until all obd's will be removed */
 594                 if ((pet_state == PET_TERMINATE) && list_empty(&pet_list))
 595                         break;
 596
 597                 /* we only get here if pet_exp != NULL, and the end of this
 598                  * loop is the only place which sets it NULL again, so lock
 599                  * is not strictly necessary. */
 600                 spin_lock(&pet_lock);
 601                 obd = list_entry(pet_list.next, struct obd_device,
 602                                  obd_evict_list);
 603                 spin_unlock(&pet_lock);
 604
 605                 expire_time = ktime_get_real_seconds() - PING_EVICT_TIMEOUT;
 606
 607                 CDEBUG(D_HA, "evicting all exports of obd %s older than %lld\n",
 608                        obd->obd_name, expire_time);
 609
 610                 /* Exports can't be deleted out of the list while we hold
 611                  * the obd lock (class_unlink_export), which means we can't
 612                  * lose the last ref on the export.  If they've already been
 613                  * removed from the list, we won't find them here. */
 614                 spin_lock(&obd->obd_dev_lock);
 615                 while (!list_empty(&obd->obd_exports_timed)) {
 616                         exp = list_entry(obd->obd_exports_timed.next,
 617                                          struct obd_export,
 618                                          exp_obd_chain_timed);
 619                         if (expire_time > exp->exp_last_request_time) {
 620                                 class_export_get(exp);
 621                                 spin_unlock(&obd->obd_dev_lock);
 622                                 LCONSOLE_WARN("%s: haven't heard from client %s"
 623                                               " (at %s) in %lld seconds. I think"
 624                                               " it's dead, and I am evicting"
 625                                               " it. exp %p, cur %lld expire %lld"
 626                                               " last %lld\n",
 627                                               obd->obd_name,
 628                                               obd_uuid2str(&exp->exp_client_uuid),
 629                                               obd_export_nid2str(exp),
 630                                               ktime_get_real_seconds() -
 631                                               exp->exp_last_request_time,
 632                                               exp, ktime_get_real_seconds(),
 633                                               expire_time,
 634                                               exp->exp_last_request_time);
 635                                 CDEBUG(D_HA, "Last request was at %lld\n",
 636                                        exp->exp_last_request_time);
 637                                 class_fail_export(exp);
 638                                 class_export_put(exp);
 639                                 spin_lock(&obd->obd_dev_lock);
 640                         } else {
 641                                 /* List is sorted, so everyone below is ok */
 642                                 break;
 643                         }
 644                 }
 645                 spin_unlock(&obd->obd_dev_lock);
 646
 647                 spin_lock(&pet_lock);
 648                 list_del_init(&obd->obd_evict_list);
 649                 spin_unlock(&pet_lock);
 650
 651                 class_decref(obd, "evictor", obd);
 652         }
 653         CDEBUG(D_HA, "Exiting Ping Evictor\n");
 654
 655         RETURN(0);
 656 }
 657
 658 void ping_evictor_start(void)
 659 {
 660         struct task_struct *task;
 661
 662         if (++pet_refcount > 1)
 663                 return;
 664
 665         INIT_LIST_HEAD(&pet_list);
 666         init_waitqueue_head(&pet_waitq);
 667
 668         task = kthread_run(ping_evictor_main, NULL, "ll_evictor");
 669         if (IS_ERR(task)) {
 670                 pet_refcount--;
 671                 CERROR("Cannot start ping evictor thread: %ld\n",
 672                         PTR_ERR(task));
 673         }
 674 }
 675 EXPORT_SYMBOL(ping_evictor_start);
 676
 677 void ping_evictor_stop(void)
 678 {
 679         if (--pet_refcount > 0)
 680                 return;
 681
 682         pet_state = PET_TERMINATE;
 683         wake_up(&pet_waitq);
 684 }
 685 EXPORT_SYMBOL(ping_evictor_stop);