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         if (atomic_read(&imp->imp_reqs) > 0)
 105                 return false;
 106
 107         /* any lock increases ns_bref being a resource holder */
 108         if (ns && atomic_read(&ns->ns_bref) > 0)
 109                 return false;
 110
 111         now = ktime_get_real_seconds();
 112         if (now - imp->imp_last_reply_time < imp->imp_idle_timeout)
 113                 return false;
 114
 115         return true;
 116 }
 117
 118 static int ptlrpc_ping(struct obd_import *imp)
 119 {
 120         struct ptlrpc_request *req;
 121
 122         ENTRY;
 123
 124         if (ptlrpc_check_import_is_idle(imp))
 125                 RETURN(ptlrpc_disconnect_and_idle_import(imp));
 126
 127         req = ptlrpc_prep_ping(imp);
 128         if (!req) {
 129                 CERROR("OOM trying to ping %s->%s\n",
 130                        imp->imp_obd->obd_uuid.uuid,
 131                        obd2cli_tgt(imp->imp_obd));
 132                 RETURN(-ENOMEM);
 133         }
 134
 135         DEBUG_REQ(D_INFO, req, "pinging %s->%s",
 136                   imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 137         ptlrpcd_add_req(req);
 138
 139         RETURN(0);
 140 }
 141
 142 static void ptlrpc_update_next_ping(struct obd_import *imp, int soon)
 143 {
 144 #ifdef CONFIG_LUSTRE_FS_PINGER
 145         time64_t time = soon ? PING_INTERVAL_SHORT : PING_INTERVAL;
 146
 147         if (imp->imp_state == LUSTRE_IMP_DISCON) {
 148                 time64_t dtime = max_t(time64_t, CONNECTION_SWITCH_MIN,
 149                                        AT_OFF ? 0 :
 150                                        at_get(&imp->imp_at.iat_net_latency));
 151                 time = min(time, dtime);
 152         }
 153         imp->imp_next_ping = ktime_get_seconds() + time;
 154 #endif /* CONFIG_LUSTRE_FS_PINGER */
 155 }
 156
 157 void ptlrpc_ping_import_soon(struct obd_import *imp)
 158 {
 159         imp->imp_next_ping = ktime_get_seconds();
 160 }
 161
 162 static inline int imp_is_deactive(struct obd_import *imp)
 163 {
 164         return imp->imp_deactive ||
 165                OBD_FAIL_CHECK(OBD_FAIL_PTLRPC_IMP_DEACTIVE);
 166 }
 167
 168 static inline time64_t ptlrpc_next_reconnect(struct obd_import *imp)
 169 {
 170         if (imp->imp_server_timeout)
 171                 return ktime_get_seconds() + (obd_timeout >> 1);
 172         else
 173                 return ktime_get_seconds() + obd_timeout;
 174 }
 175
 176 static time64_t pinger_check_timeout(time64_t time)
 177 {
 178         struct timeout_item *item;
 179         time64_t timeout = PING_INTERVAL;
 180
 181         /* This list is sorted in increasing timeout order */
 182         mutex_lock(&pinger_mutex);
 183         list_for_each_entry(item, &timeout_list, ti_chain) {
 184                 time64_t ti_timeout = item->ti_timeout;
 185
 186                 if (timeout > ti_timeout)
 187                         timeout = ti_timeout;
 188                 break;
 189         }
 190         mutex_unlock(&pinger_mutex);
 191
 192         return time + timeout - ktime_get_seconds();
 193 }
 194
 195 static bool ir_up;
 196
 197 void ptlrpc_pinger_ir_up(void)
 198 {
 199         CDEBUG(D_HA, "IR up\n");
 200         ir_up = true;
 201 }
 202 EXPORT_SYMBOL(ptlrpc_pinger_ir_up);
 203
 204 void ptlrpc_pinger_ir_down(void)
 205 {
 206         CDEBUG(D_HA, "IR down\n");
 207         ir_up = false;
 208 }
 209 EXPORT_SYMBOL(ptlrpc_pinger_ir_down);
 210
 211 static void ptlrpc_pinger_process_import(struct obd_import *imp,
 212                                          time64_t this_ping)
 213 {
 214         int level;
 215         int force;
 216         int force_next;
 217         int suppress;
 218
 219         spin_lock(&imp->imp_lock);
 220
 221         level = imp->imp_state;
 222         force = imp->imp_force_verify;
 223         force_next = imp->imp_force_next_verify;
 224         /*
 225          * This will be used below only if the import is "FULL".
 226          */
 227         suppress = ir_up && OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS);
 228
 229         imp->imp_force_verify = 0;
 230
 231         if (imp->imp_next_ping - 5 >= this_ping && !force) {
 232                 spin_unlock(&imp->imp_lock);
 233                 return;
 234         }
 235
 236         imp->imp_force_next_verify = 0;
 237
 238         CDEBUG(level == LUSTRE_IMP_FULL ? D_INFO : D_HA,
 239                "%s->%s: level %s/%u force %u force_next %u deactive %u pingable %u suppress %u\n",
 240                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 241                ptlrpc_import_state_name(level), level, force, force_next,
 242                imp->imp_deactive, imp->imp_pingable, suppress);
 243
 244         if (level == LUSTRE_IMP_DISCON && !imp_is_deactive(imp)) {
 245                 /* wait for a while before trying recovery again */
 246                 imp->imp_next_ping = ptlrpc_next_reconnect(imp);
 247                 spin_unlock(&imp->imp_lock);
 248                 if (!imp->imp_no_pinger_recover ||
 249                     imp->imp_connect_error == -EAGAIN)
 250                         ptlrpc_initiate_recovery(imp);
 251         } else if (level != LUSTRE_IMP_FULL || imp->imp_obd->obd_no_recov ||
 252                    imp_is_deactive(imp)) {
 253                 CDEBUG(D_HA,
 254                        "%s->%s: not pinging (in recovery or recovery disabled: %s)\n",
 255                        imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 256                        ptlrpc_import_state_name(level));
 257                 if (force)
 258                         imp->imp_force_verify = 1;
 259                 spin_unlock(&imp->imp_lock);
 260         } else if ((imp->imp_pingable && !suppress) || force_next || force) {
 261                 spin_unlock(&imp->imp_lock);
 262                 ptlrpc_ping(imp);
 263         } else {
 264                 spin_unlock(&imp->imp_lock);
 265         }
 266 }
 267
 268 static struct workqueue_struct *pinger_wq;
 269 static void ptlrpc_pinger_main(struct work_struct *ws);
 270 static DECLARE_DELAYED_WORK(ping_work, ptlrpc_pinger_main);
 271
 272 static void ptlrpc_pinger_main(struct work_struct *ws)
 273 {
 274         time64_t this_ping = ktime_get_seconds();
 275         time64_t time_to_next_wake;
 276         struct timeout_item *item;
 277         struct obd_import *imp;
 278         struct list_head *iter;
 279
 280         do {
 281                 mutex_lock(&pinger_mutex);
 282                 list_for_each_entry(item, &timeout_list, ti_chain)
 283                         item->ti_cb(item, item->ti_cb_data);
 284
 285                 list_for_each(iter, &pinger_imports) {
 286                         imp = list_entry(iter, struct obd_import,
 287                                          imp_pinger_chain);
 288
 289                         ptlrpc_pinger_process_import(imp, this_ping);
 290                         /* obd_timeout might have changed */
 291                         if (imp->imp_pingable && imp->imp_next_ping &&
 292                             imp->imp_next_ping > this_ping + PING_INTERVAL)
 293                                 ptlrpc_update_next_ping(imp, 0);
 294                 }
 295                 mutex_unlock(&pinger_mutex);
 296                 /* update memory usage info */
 297                 obd_update_maxusage();
 298
 299                 /* Wait until the next ping time, or until we're stopped. */
 300                 time_to_next_wake = pinger_check_timeout(this_ping);
 301                 /*
 302                  * The ping sent by ptlrpc_send_rpc may get sent out
 303                  * say .01 second after this.
 304                  * ptlrpc_pinger_sending_on_import will then set the
 305                  * next ping time to next_ping + .01 sec, which means
 306                  * we will SKIP the next ping at next_ping, and the
 307                  * ping will get sent 2 timeouts from now!  Beware.
 308                  */
 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 CONFIG_LUSTRE_FS_PINGER
 320         if (pinger_wq)
 321                 return -EALREADY;
 322
 323         pinger_wq = cfs_cpt_bind_workqueue("ptlrpc_pinger", cfs_cpt_tab,
 324                                            0, CFS_CPT_ANY, 1);
 325         if (IS_ERR(pinger_wq)) {
 326                 CERROR("cannot start pinger workqueue\n");
 327                 return PTR_ERR(pinger_wq);
 328         }
 329
 330         queue_delayed_work(pinger_wq, &ping_work, 0);
 331
 332         if (suppress_pings)
 333                 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");
 334 #endif
 335         return 0;
 336 }
 337
 338 int ptlrpc_pinger_remove_timeouts(void);
 339
 340 int ptlrpc_stop_pinger(void)
 341 {
 342 #ifdef CONFIG_LUSTRE_FS_PINGER
 343         if (!pinger_wq)
 344                 return -EALREADY;
 345
 346         ptlrpc_pinger_remove_timeouts();
 347
 348         cancel_delayed_work_sync(&ping_work);
 349         destroy_workqueue(pinger_wq);
 350         pinger_wq = NULL;
 351 #endif
 352         return 0;
 353 }
 354
 355 void ptlrpc_pinger_sending_on_import(struct obd_import *imp)
 356 {
 357         ptlrpc_update_next_ping(imp, 0);
 358 }
 359
 360 void ptlrpc_pinger_commit_expected(struct obd_import *imp)
 361 {
 362         ptlrpc_update_next_ping(imp, 1);
 363         assert_spin_locked(&imp->imp_lock);
 364         /*
 365          * Avoid reading stale imp_connect_data.  When not sure if pings are
 366          * expected or not on next connection, we assume they are not and force
 367          * one anyway to guarantee the chance of updating
 368          * imp_peer_committed_transno.
 369          */
 370         if (imp->imp_state != LUSTRE_IMP_FULL ||
 371             OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS))
 372                 imp->imp_force_next_verify = 1;
 373 }
 374
 375 int ptlrpc_pinger_add_import(struct obd_import *imp)
 376 {
 377         ENTRY;
 378         if (!list_empty(&imp->imp_pinger_chain))
 379                 RETURN(-EALREADY);
 380
 381         mutex_lock(&pinger_mutex);
 382         CDEBUG(D_HA, "adding pingable import %s->%s\n",
 383                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 384         /* if we add to pinger we want recovery on this import */
 385         imp->imp_obd->obd_no_recov = 0;
 386         ptlrpc_update_next_ping(imp, 0);
 387         /* XXX sort, blah blah */
 388         list_add_tail(&imp->imp_pinger_chain, &pinger_imports);
 389         class_import_get(imp);
 390
 391         ptlrpc_pinger_wake_up();
 392         mutex_unlock(&pinger_mutex);
 393
 394         RETURN(0);
 395 }
 396 EXPORT_SYMBOL(ptlrpc_pinger_add_import);
 397
 398 int ptlrpc_pinger_del_import(struct obd_import *imp)
 399 {
 400         ENTRY;
 401
 402         if (list_empty(&imp->imp_pinger_chain))
 403                 RETURN(-ENOENT);
 404
 405         mutex_lock(&pinger_mutex);
 406         list_del_init(&imp->imp_pinger_chain);
 407         CDEBUG(D_HA, "removing pingable import %s->%s\n",
 408                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 409         /* if we remove from pinger we don't want recovery on this import */
 410         imp->imp_obd->obd_no_recov = 1;
 411         class_import_put(imp);
 412         mutex_unlock(&pinger_mutex);
 413         RETURN(0);
 414 }
 415 EXPORT_SYMBOL(ptlrpc_pinger_del_import);
 416
 417 /**
 418  * Register a timeout callback to the pinger list, and the callback will
 419  * be called when timeout happens.
 420  */
 421 static struct timeout_item *ptlrpc_new_timeout(time64_t time,
 422                                                enum timeout_event event,
 423                                                timeout_cb_t cb, void *data)
 424 {
 425         struct timeout_item *ti;
 426
 427         OBD_ALLOC_PTR(ti);
 428         if (!ti)
 429                 return NULL;
 430
 431         INIT_LIST_HEAD(&ti->ti_obd_list);
 432         INIT_LIST_HEAD(&ti->ti_chain);
 433         ti->ti_timeout = time;
 434         ti->ti_event = event;
 435         ti->ti_cb = cb;
 436         ti->ti_cb_data = data;
 437
 438         return ti;
 439 }
 440
 441 /**
 442  * Register timeout event on the the pinger thread.
 443  * Note: the timeout list is an sorted list with increased timeout value.
 444  */
 445 static struct timeout_item*
 446 ptlrpc_pinger_register_timeout(time64_t time, enum timeout_event event,
 447                                timeout_cb_t cb, void *data)
 448 {
 449         struct timeout_item *item, *tmp;
 450
 451         LASSERT(mutex_is_locked(&pinger_mutex));
 452
 453         list_for_each_entry(item, &timeout_list, ti_chain)
 454                 if (item->ti_event == event)
 455                         goto out;
 456
 457         item = ptlrpc_new_timeout(time, event, cb, data);
 458         if (item) {
 459                 list_for_each_entry_reverse(tmp, &timeout_list, ti_chain) {
 460                         if (tmp->ti_timeout < time) {
 461                                 list_add(&item->ti_chain, &tmp->ti_chain);
 462                                 goto out;
 463                         }
 464                 }
 465                 list_add(&item->ti_chain, &timeout_list);
 466         }
 467 out:
 468         return item;
 469 }
 470
 471 /* Add a client_obd to the timeout event list, when timeout(@time)
 472  * happens, the callback(@cb) will be called.
 473  */
 474 int ptlrpc_add_timeout_client(time64_t time, enum timeout_event event,
 475                               timeout_cb_t cb, void *data,
 476                               struct list_head *obd_list)
 477 {
 478         struct timeout_item *ti;
 479
 480         mutex_lock(&pinger_mutex);
 481         ti = ptlrpc_pinger_register_timeout(time, event, cb, data);
 482         if (!ti) {
 483                 mutex_unlock(&pinger_mutex);
 484                 return -EINVAL;
 485         }
 486         list_add(obd_list, &ti->ti_obd_list);
 487         mutex_unlock(&pinger_mutex);
 488         return 0;
 489 }
 490 EXPORT_SYMBOL(ptlrpc_add_timeout_client);
 491
 492 int ptlrpc_del_timeout_client(struct list_head *obd_list,
 493                               enum timeout_event event)
 494 {
 495         struct timeout_item *ti = NULL, *item;
 496
 497         if (list_empty(obd_list))
 498                 return 0;
 499         mutex_lock(&pinger_mutex);
 500         list_del_init(obd_list);
 501         /**
 502          * If there are no obd attached to the timeout event
 503          * list, remove this timeout event from the pinger
 504          */
 505         list_for_each_entry(item, &timeout_list, ti_chain) {
 506                 if (item->ti_event == event) {
 507                         ti = item;
 508                         break;
 509                 }
 510         }
 511         LASSERTF(ti, "ti is NULL !\n");
 512         if (list_empty(&ti->ti_obd_list)) {
 513                 list_del(&ti->ti_chain);
 514                 OBD_FREE_PTR(ti);
 515         }
 516         mutex_unlock(&pinger_mutex);
 517         return 0;
 518 }
 519 EXPORT_SYMBOL(ptlrpc_del_timeout_client);
 520
 521 int ptlrpc_pinger_remove_timeouts(void)
 522 {
 523         struct timeout_item *item, *tmp;
 524
 525         mutex_lock(&pinger_mutex);
 526         list_for_each_entry_safe(item, tmp, &timeout_list, ti_chain) {
 527                 LASSERT(list_empty(&item->ti_obd_list));
 528                 list_del(&item->ti_chain);
 529                 OBD_FREE_PTR(item);
 530         }
 531         mutex_unlock(&pinger_mutex);
 532         return 0;
 533 }
 534
 535 void ptlrpc_pinger_wake_up(void)
 536 {
 537 #ifdef CONFIG_LUSTRE_FS_PINGER
 538         mod_delayed_work(pinger_wq, &ping_work, 0);
 539 #endif
 540 }
 541
 542 /* Ping evictor thread */
 543 #define PET_READY     1
 544 #define PET_TERMINATE 2
 545
 546 static int pet_refcount;
 547 static int pet_state;
 548 static wait_queue_head_t pet_waitq;
 549 static LIST_HEAD(pet_list);
 550 static DEFINE_SPINLOCK(pet_lock);
 551
 552 int ping_evictor_wake(struct obd_export *exp)
 553 {
 554         struct obd_device *obd;
 555
 556         spin_lock(&pet_lock);
 557         if (pet_state != PET_READY) {
 558                 /* eventually the new obd will call here again. */
 559                 spin_unlock(&pet_lock);
 560                 return 1;
 561         }
 562
 563         obd = class_exp2obd(exp);
 564         if (list_empty(&obd->obd_evict_list)) {
 565                 class_incref(obd, "evictor", obd);
 566                 list_add(&obd->obd_evict_list, &pet_list);
 567         }
 568         spin_unlock(&pet_lock);
 569
 570         wake_up(&pet_waitq);
 571         return 0;
 572 }
 573
 574 static int ping_evictor_main(void *arg)
 575 {
 576         struct obd_device *obd;
 577         struct obd_export *exp;
 578         time64_t expire_time;
 579
 580         ENTRY;
 581         unshare_fs_struct();
 582
 583         CDEBUG(D_HA, "Starting Ping Evictor\n");
 584         pet_state = PET_READY;
 585         while (1) {
 586                 wait_event_idle(pet_waitq,
 587                                 (!list_empty(&pet_list)) ||
 588                                 (pet_state == PET_TERMINATE));
 589
 590                 /* loop until all obd's will be removed */
 591                 if ((pet_state == PET_TERMINATE) && list_empty(&pet_list))
 592                         break;
 593
 594                 /*
 595                  * we only get here if pet_exp != NULL, and the end of this
 596                  * loop is the only place which sets it NULL again, so lock
 597                  * is not strictly necessary.
 598                  */
 599                 spin_lock(&pet_lock);
 600                 obd = list_entry(pet_list.next, struct obd_device,
 601                                  obd_evict_list);
 602                 spin_unlock(&pet_lock);
 603
 604                 expire_time = ktime_get_real_seconds() - PING_EVICT_TIMEOUT;
 605
 606                 CDEBUG(D_HA, "evicting all exports of obd %s older than %lld\n",
 607                        obd->obd_name, expire_time);
 608
 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                  */
 615                 spin_lock(&obd->obd_dev_lock);
 616                 while (!list_empty(&obd->obd_exports_timed)) {
 617                         exp = list_entry(obd->obd_exports_timed.next,
 618                                          struct obd_export,
 619                                          exp_obd_chain_timed);
 620                         if (expire_time > exp->exp_last_request_time) {
 621                                 struct obd_uuid *client_uuid;
 622
 623                                 class_export_get(exp);
 624                                 client_uuid = &exp->exp_client_uuid;
 625                                 spin_unlock(&obd->obd_dev_lock);
 626                                 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",
 627                                               obd->obd_name,
 628                                               obd_uuid2str(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_waitqueue_head(&pet_waitq);
 666
 667         task = kthread_run(ping_evictor_main, NULL, "ll_evictor");
 668         if (IS_ERR(task)) {
 669                 pet_refcount--;
 670                 CERROR("Cannot start ping evictor thread: %ld\n",
 671                         PTR_ERR(task));
 672         }
 673 }
 674 EXPORT_SYMBOL(ping_evictor_start);
 675
 676 void ping_evictor_stop(void)
 677 {
 678         if (--pet_refcount > 0)
 679                 return;
 680
 681         pet_state = PET_TERMINATE;
 682         wake_up(&pet_waitq);
 683 }
 684 EXPORT_SYMBOL(ping_evictor_stop);