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
  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         }
 271 }
 272
 273 static struct workqueue_struct *pinger_wq;
 274 static void ptlrpc_pinger_main(struct work_struct *ws);
 275 static DECLARE_DELAYED_WORK(ping_work, ptlrpc_pinger_main);
 276
 277 static void ptlrpc_pinger_main(struct work_struct *ws)
 278 {
 279         time64_t this_ping = ktime_get_seconds();
 280         time64_t time_to_next_wake;
 281         struct timeout_item *item;
 282         struct obd_import *imp;
 283         struct list_head *iter;
 284
 285         do {
 286                 mutex_lock(&pinger_mutex);
 287                 list_for_each_entry(item, &timeout_list, ti_chain)
 288                         item->ti_cb(item, item->ti_cb_data);
 289
 290                 list_for_each(iter, &pinger_imports) {
 291                         imp = list_entry(iter, struct obd_import,
 292                                          imp_pinger_chain);
 293
 294                         ptlrpc_pinger_process_import(imp, this_ping);
 295                         /* obd_timeout might have changed */
 296                         if (imp->imp_pingable && imp->imp_next_ping &&
 297                             imp->imp_next_ping > this_ping + PING_INTERVAL)
 298                                 ptlrpc_update_next_ping(imp, 0);
 299                 }
 300                 mutex_unlock(&pinger_mutex);
 301                 /* update memory usage info */
 302                 obd_update_maxusage();
 303
 304                 /* Wait until the next ping time, or until we're stopped. */
 305                 time_to_next_wake = pinger_check_timeout(this_ping);
 306                 /*
 307                  * The ping sent by ptlrpc_send_rpc may get sent out
 308                  * say .01 second after this.
 309                  * ptlrpc_pinger_sending_on_import will then set the
 310                  * next ping time to next_ping + .01 sec, which means
 311                  * we will SKIP the next ping at next_ping, and the
 312                  * ping will get sent 2 timeouts from now!  Beware.
 313                  */
 314                 CDEBUG(D_INFO, "next wakeup in %lld (%lld)\n",
 315                        time_to_next_wake, this_ping + PING_INTERVAL);
 316         } while (time_to_next_wake <= 0);
 317
 318         queue_delayed_work(pinger_wq, &ping_work,
 319                            cfs_time_seconds(max(time_to_next_wake, 1LL)));
 320 }
 321
 322 int ptlrpc_start_pinger(void)
 323 {
 324 #ifdef ENABLE_PINGER
 325         if (pinger_wq)
 326                 return -EALREADY;
 327
 328         pinger_wq = alloc_workqueue("ptlrpc_pinger", 0, 1);
 329         if (!pinger_wq) {
 330                 CERROR("cannot start pinger workqueue\n");
 331                 return -ENOMEM;
 332         }
 333
 334         queue_delayed_work(pinger_wq, &ping_work, 0);
 335
 336         if (suppress_pings)
 337                 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");
 338 #endif
 339         return 0;
 340 }
 341
 342 int ptlrpc_pinger_remove_timeouts(void);
 343
 344 int ptlrpc_stop_pinger(void)
 345 {
 346 #ifdef ENABLE_PINGER
 347         if (!pinger_wq)
 348                 return -EALREADY;
 349
 350         ptlrpc_pinger_remove_timeouts();
 351
 352         cancel_delayed_work_sync(&ping_work);
 353         destroy_workqueue(pinger_wq);
 354         pinger_wq = NULL;
 355 #endif
 356         return 0;
 357 }
 358
 359 void ptlrpc_pinger_sending_on_import(struct obd_import *imp)
 360 {
 361         ptlrpc_update_next_ping(imp, 0);
 362 }
 363
 364 void ptlrpc_pinger_commit_expected(struct obd_import *imp)
 365 {
 366         ptlrpc_update_next_ping(imp, 1);
 367         assert_spin_locked(&imp->imp_lock);
 368         /*
 369          * Avoid reading stale imp_connect_data.  When not sure if pings are
 370          * expected or not on next connection, we assume they are not and force
 371          * one anyway to guarantee the chance of updating
 372          * imp_peer_committed_transno.
 373          */
 374         if (imp->imp_state != LUSTRE_IMP_FULL ||
 375             OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS))
 376                 imp->imp_force_next_verify = 1;
 377 }
 378
 379 int ptlrpc_pinger_add_import(struct obd_import *imp)
 380 {
 381         ENTRY;
 382         if (!list_empty(&imp->imp_pinger_chain))
 383                 RETURN(-EALREADY);
 384
 385         mutex_lock(&pinger_mutex);
 386         CDEBUG(D_HA, "adding pingable import %s->%s\n",
 387                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 388         /* if we add to pinger we want recovery on this import */
 389         imp->imp_obd->obd_no_recov = 0;
 390         ptlrpc_update_next_ping(imp, 0);
 391         /* XXX sort, blah blah */
 392         list_add_tail(&imp->imp_pinger_chain, &pinger_imports);
 393         class_import_get(imp);
 394
 395         ptlrpc_pinger_wake_up();
 396         mutex_unlock(&pinger_mutex);
 397
 398         RETURN(0);
 399 }
 400 EXPORT_SYMBOL(ptlrpc_pinger_add_import);
 401
 402 int ptlrpc_pinger_del_import(struct obd_import *imp)
 403 {
 404         ENTRY;
 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 static struct timeout_item *ptlrpc_new_timeout(time64_t time,
 426                                                enum timeout_event event,
 427                                                timeout_cb_t cb, void *data)
 428 {
 429         struct timeout_item *ti;
 430
 431         OBD_ALLOC_PTR(ti);
 432         if (!ti)
 433                 return NULL;
 434
 435         INIT_LIST_HEAD(&ti->ti_obd_list);
 436         INIT_LIST_HEAD(&ti->ti_chain);
 437         ti->ti_timeout = time;
 438         ti->ti_event = event;
 439         ti->ti_cb = cb;
 440         ti->ti_cb_data = data;
 441
 442         return ti;
 443 }
 444
 445 /**
 446  * Register timeout event on the the pinger thread.
 447  * Note: the timeout list is an sorted list with increased timeout value.
 448  */
 449 static struct timeout_item*
 450 ptlrpc_pinger_register_timeout(time64_t time, enum timeout_event event,
 451                                timeout_cb_t cb, void *data)
 452 {
 453         struct timeout_item *item, *tmp;
 454
 455         LASSERT(mutex_is_locked(&pinger_mutex));
 456
 457         list_for_each_entry(item, &timeout_list, ti_chain)
 458                 if (item->ti_event == event)
 459                         goto out;
 460
 461         item = ptlrpc_new_timeout(time, event, cb, data);
 462         if (item) {
 463                 list_for_each_entry_reverse(tmp, &timeout_list, ti_chain) {
 464                         if (tmp->ti_timeout < time) {
 465                                 list_add(&item->ti_chain, &tmp->ti_chain);
 466                                 goto out;
 467                         }
 468                 }
 469                 list_add(&item->ti_chain, &timeout_list);
 470         }
 471 out:
 472         return item;
 473 }
 474
 475 /* Add a client_obd to the timeout event list, when timeout(@time)
 476  * happens, the callback(@cb) will be called.
 477  */
 478 int ptlrpc_add_timeout_client(time64_t time, enum timeout_event event,
 479                               timeout_cb_t cb, void *data,
 480                               struct list_head *obd_list)
 481 {
 482         struct timeout_item *ti;
 483
 484         mutex_lock(&pinger_mutex);
 485         ti = ptlrpc_pinger_register_timeout(time, event, cb, data);
 486         if (!ti) {
 487                 mutex_unlock(&pinger_mutex);
 488                 return -EINVAL;
 489         }
 490         list_add(obd_list, &ti->ti_obd_list);
 491         mutex_unlock(&pinger_mutex);
 492         return 0;
 493 }
 494 EXPORT_SYMBOL(ptlrpc_add_timeout_client);
 495
 496 int ptlrpc_del_timeout_client(struct list_head *obd_list,
 497                               enum timeout_event event)
 498 {
 499         struct timeout_item *ti = NULL, *item;
 500
 501         if (list_empty(obd_list))
 502                 return 0;
 503         mutex_lock(&pinger_mutex);
 504         list_del_init(obd_list);
 505         /**
 506          * If there are no obd attached to the timeout event
 507          * list, remove this timeout event from the pinger
 508          */
 509         list_for_each_entry(item, &timeout_list, ti_chain) {
 510                 if (item->ti_event == event) {
 511                         ti = item;
 512                         break;
 513                 }
 514         }
 515         LASSERTF(ti, "ti is NULL !\n");
 516         if (list_empty(&ti->ti_obd_list)) {
 517                 list_del(&ti->ti_chain);
 518                 OBD_FREE_PTR(ti);
 519         }
 520         mutex_unlock(&pinger_mutex);
 521         return 0;
 522 }
 523 EXPORT_SYMBOL(ptlrpc_del_timeout_client);
 524
 525 int ptlrpc_pinger_remove_timeouts(void)
 526 {
 527         struct timeout_item *item, *tmp;
 528
 529         mutex_lock(&pinger_mutex);
 530         list_for_each_entry_safe(item, tmp, &timeout_list, ti_chain) {
 531                 LASSERT(list_empty(&item->ti_obd_list));
 532                 list_del(&item->ti_chain);
 533                 OBD_FREE_PTR(item);
 534         }
 535         mutex_unlock(&pinger_mutex);
 536         return 0;
 537 }
 538
 539 void ptlrpc_pinger_wake_up()
 540 {
 541 #ifdef ENABLE_PINGER
 542         mod_delayed_work(pinger_wq, &ping_work, 0);
 543 #endif
 544 }
 545
 546 /* Ping evictor thread */
 547 #define PET_READY     1
 548 #define PET_TERMINATE 2
 549
 550 static int pet_refcount;
 551 static int pet_state;
 552 static wait_queue_head_t pet_waitq;
 553 static struct list_head pet_list;
 554 static DEFINE_SPINLOCK(pet_lock);
 555
 556 int ping_evictor_wake(struct obd_export *exp)
 557 {
 558         struct obd_device *obd;
 559
 560         spin_lock(&pet_lock);
 561         if (pet_state != PET_READY) {
 562                 /* eventually the new obd will call here again. */
 563                 spin_unlock(&pet_lock);
 564                 return 1;
 565         }
 566
 567         obd = class_exp2obd(exp);
 568         if (list_empty(&obd->obd_evict_list)) {
 569                 class_incref(obd, "evictor", obd);
 570                 list_add(&obd->obd_evict_list, &pet_list);
 571         }
 572         spin_unlock(&pet_lock);
 573
 574         wake_up(&pet_waitq);
 575         return 0;
 576 }
 577
 578 static int ping_evictor_main(void *arg)
 579 {
 580         struct obd_device *obd;
 581         struct obd_export *exp;
 582         struct l_wait_info lwi = { 0 };
 583         time64_t expire_time;
 584
 585         ENTRY;
 586         unshare_fs_struct();
 587
 588         CDEBUG(D_HA, "Starting Ping Evictor\n");
 589         pet_state = PET_READY;
 590         while (1) {
 591                 l_wait_event(pet_waitq, (!list_empty(&pet_list)) ||
 592                              (pet_state == PET_TERMINATE), &lwi);
 593
 594                 /* loop until all obd's will be removed */
 595                 if ((pet_state == PET_TERMINATE) && list_empty(&pet_list))
 596                         break;
 597
 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                  */
 603                 spin_lock(&pet_lock);
 604                 obd = list_entry(pet_list.next, struct obd_device,
 605                                  obd_evict_list);
 606                 spin_unlock(&pet_lock);
 607
 608                 expire_time = ktime_get_real_seconds() - PING_EVICT_TIMEOUT;
 609
 610                 CDEBUG(D_HA, "evicting all exports of obd %s older than %lld\n",
 611                        obd->obd_name, expire_time);
 612
 613                 /*
 614                  * Exports can't be deleted out of the list while we hold
 615                  * the obd lock (class_unlink_export), which means we can't
 616                  * lose the last ref on the export.  If they've already been
 617                  * removed from the list, we won't find them here.
 618                  */
 619                 spin_lock(&obd->obd_dev_lock);
 620                 while (!list_empty(&obd->obd_exports_timed)) {
 621                         exp = list_entry(obd->obd_exports_timed.next,
 622                                          struct obd_export,
 623                                          exp_obd_chain_timed);
 624                         if (expire_time > exp->exp_last_request_time) {
 625                                 struct obd_uuid *client_uuid;
 626
 627                                 class_export_get(exp);
 628                                 client_uuid = &exp->exp_client_uuid;
 629                                 spin_unlock(&obd->obd_dev_lock);
 630                                 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",
 631                                               obd->obd_name,
 632                                               obd_uuid2str(client_uuid),
 633                                               obd_export_nid2str(exp),
 634                                               ktime_get_real_seconds() -
 635                                               exp->exp_last_request_time,
 636                                               exp, ktime_get_real_seconds(),
 637                                               expire_time,
 638                                               exp->exp_last_request_time);
 639                                 CDEBUG(D_HA, "Last request was at %lld\n",
 640                                        exp->exp_last_request_time);
 641                                 class_fail_export(exp);
 642                                 class_export_put(exp);
 643                                 spin_lock(&obd->obd_dev_lock);
 644                         } else {
 645                                 /* List is sorted, so everyone below is ok */
 646                                 break;
 647                         }
 648                 }
 649                 spin_unlock(&obd->obd_dev_lock);
 650
 651                 spin_lock(&pet_lock);
 652                 list_del_init(&obd->obd_evict_list);
 653                 spin_unlock(&pet_lock);
 654
 655                 class_decref(obd, "evictor", obd);
 656         }
 657         CDEBUG(D_HA, "Exiting Ping Evictor\n");
 658
 659         RETURN(0);
 660 }
 661
 662 void ping_evictor_start(void)
 663 {
 664         struct task_struct *task;
 665
 666         if (++pet_refcount > 1)
 667                 return;
 668
 669         INIT_LIST_HEAD(&pet_list);
 670         init_waitqueue_head(&pet_waitq);
 671
 672         task = kthread_run(ping_evictor_main, NULL, "ll_evictor");
 673         if (IS_ERR(task)) {
 674                 pet_refcount--;
 675                 CERROR("Cannot start ping evictor thread: %ld\n",
 676                         PTR_ERR(task));
 677         }
 678 }
 679 EXPORT_SYMBOL(ping_evictor_start);
 680
 681 void ping_evictor_stop(void)
 682 {
 683         if (--pet_refcount > 0)
 684                 return;
 685
 686         pet_state = PET_TERMINATE;
 687         wake_up(&pet_waitq);
 688 }
 689 EXPORT_SYMBOL(ping_evictor_stop);