Pileus Git - ~andy/linux/blob - drivers/staging/lustre/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.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2012, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * lustre/ptlrpc/pinger.c
  37  *
  38  * Portal-RPC reconnection and replay operations, for use in recovery.
  39  */
  40
  41 #define DEBUG_SUBSYSTEM S_RPC
  42
  43 #include <obd_support.h>
  44 #include <obd_class.h>
  45 #include "ptlrpc_internal.h"
  46
  47 static int suppress_pings;
  48 module_param(suppress_pings, int, 0644);
  49 MODULE_PARM_DESC(suppress_pings, "Suppress pings");
  50
  51 struct mutex pinger_mutex;
  52 static LIST_HEAD(pinger_imports);
  53 static struct list_head timeout_list = 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         req = ptlrpc_prep_ping(obd->u.cli.cl_import);
  81         if (req == NULL)
  82                 return -ENOMEM;
  83
  84         req->rq_send_state = LUSTRE_IMP_FULL;
  85
  86         rc = ptlrpc_queue_wait(req);
  87
  88         ptlrpc_req_finished(req);
  89
  90         return rc;
  91 }
  92 EXPORT_SYMBOL(ptlrpc_obd_ping);
  93
  94 int ptlrpc_ping(struct obd_import *imp)
  95 {
  96         struct ptlrpc_request *req;
  97
  98         req = ptlrpc_prep_ping(imp);
  99         if (req == NULL) {
 100                 CERROR("OOM trying to ping %s->%s\n",
 101                        imp->imp_obd->obd_uuid.uuid,
 102                        obd2cli_tgt(imp->imp_obd));
 103                 return -ENOMEM;
 104         }
 105
 106         DEBUG_REQ(D_INFO, req, "pinging %s->%s",
 107                   imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 108         ptlrpcd_add_req(req, PDL_POLICY_ROUND, -1);
 109
 110         return 0;
 111 }
 112
 113 void ptlrpc_update_next_ping(struct obd_import *imp, int soon)
 114 {
 115         int time = soon ? PING_INTERVAL_SHORT : PING_INTERVAL;
 116         if (imp->imp_state == LUSTRE_IMP_DISCON) {
 117                 int dtime = max_t(int, CONNECTION_SWITCH_MIN,
 118                                   AT_OFF ? 0 :
 119                                   at_get(&imp->imp_at.iat_net_latency));
 120                 time = min(time, dtime);
 121         }
 122         imp->imp_next_ping = cfs_time_shift(time);
 123 }
 124
 125 void ptlrpc_ping_import_soon(struct obd_import *imp)
 126 {
 127         imp->imp_next_ping = cfs_time_current();
 128 }
 129
 130 static inline int imp_is_deactive(struct obd_import *imp)
 131 {
 132         return (imp->imp_deactive ||
 133                 OBD_FAIL_CHECK(OBD_FAIL_PTLRPC_IMP_DEACTIVE));
 134 }
 135
 136 static inline int ptlrpc_next_reconnect(struct obd_import *imp)
 137 {
 138         if (imp->imp_server_timeout)
 139                 return cfs_time_shift(obd_timeout / 2);
 140         else
 141                 return cfs_time_shift(obd_timeout);
 142 }
 143
 144 cfs_duration_t pinger_check_timeout(cfs_time_t time)
 145 {
 146         struct timeout_item *item;
 147         cfs_time_t timeout = PING_INTERVAL;
 148
 149         /* The timeout list is a increase order sorted list */
 150         mutex_lock(&pinger_mutex);
 151         list_for_each_entry(item, &timeout_list, ti_chain) {
 152                 int ti_timeout = item->ti_timeout;
 153                 if (timeout > ti_timeout)
 154                         timeout = ti_timeout;
 155                 break;
 156         }
 157         mutex_unlock(&pinger_mutex);
 158
 159         return cfs_time_sub(cfs_time_add(time, cfs_time_seconds(timeout)),
 160                                          cfs_time_current());
 161 }
 162
 163 static bool ir_up;
 164
 165 void ptlrpc_pinger_ir_up(void)
 166 {
 167         CDEBUG(D_HA, "IR up\n");
 168         ir_up = true;
 169 }
 170 EXPORT_SYMBOL(ptlrpc_pinger_ir_up);
 171
 172 void ptlrpc_pinger_ir_down(void)
 173 {
 174         CDEBUG(D_HA, "IR down\n");
 175         ir_up = false;
 176 }
 177 EXPORT_SYMBOL(ptlrpc_pinger_ir_down);
 178
 179 static void ptlrpc_pinger_process_import(struct obd_import *imp,
 180                                          unsigned long this_ping)
 181 {
 182         int level;
 183         int force;
 184         int force_next;
 185         int suppress;
 186
 187         spin_lock(&imp->imp_lock);
 188
 189         level = imp->imp_state;
 190         force = imp->imp_force_verify;
 191         force_next = imp->imp_force_next_verify;
 192         /*
 193          * This will be used below only if the import is "FULL".
 194          */
 195         suppress = ir_up && OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS);
 196
 197         imp->imp_force_verify = 0;
 198
 199         if (cfs_time_aftereq(imp->imp_next_ping - 5 * CFS_TICK, this_ping) &&
 200             !force) {
 201                 spin_unlock(&imp->imp_lock);
 202                 return;
 203         }
 204
 205         imp->imp_force_next_verify = 0;
 206
 207         spin_unlock(&imp->imp_lock);
 208
 209         CDEBUG(level == LUSTRE_IMP_FULL ? D_INFO : D_HA, "%s->%s: level %s/%u "
 210                "force %u force_next %u deactive %u pingable %u suppress %u\n",
 211                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 212                ptlrpc_import_state_name(level), level, force, force_next,
 213                imp->imp_deactive, imp->imp_pingable, suppress);
 214
 215         if (level == LUSTRE_IMP_DISCON && !imp_is_deactive(imp)) {
 216                 /* wait for a while before trying recovery again */
 217                 imp->imp_next_ping = ptlrpc_next_reconnect(imp);
 218                 if (!imp->imp_no_pinger_recover)
 219                         ptlrpc_initiate_recovery(imp);
 220         } else if (level != LUSTRE_IMP_FULL ||
 221                    imp->imp_obd->obd_no_recov ||
 222                    imp_is_deactive(imp)) {
 223                 CDEBUG(D_HA, "%s->%s: not pinging (in recovery "
 224                        "or recovery disabled: %s)\n",
 225                        imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 226                        ptlrpc_import_state_name(level));
 227         } else if ((imp->imp_pingable && !suppress) || force_next || force) {
 228                 ptlrpc_ping(imp);
 229         }
 230 }
 231
 232 static int ptlrpc_pinger_main(void *arg)
 233 {
 234         struct ptlrpc_thread *thread = (struct ptlrpc_thread *)arg;
 235
 236         /* Record that the thread is running */
 237         thread_set_flags(thread, SVC_RUNNING);
 238         wake_up(&thread->t_ctl_waitq);
 239
 240         /* And now, loop forever, pinging as needed. */
 241         while (1) {
 242                 cfs_time_t this_ping = cfs_time_current();
 243                 struct l_wait_info lwi;
 244                 cfs_duration_t time_to_next_wake;
 245                 struct timeout_item *item;
 246                 struct list_head *iter;
 247
 248                 mutex_lock(&pinger_mutex);
 249                 list_for_each_entry(item, &timeout_list, ti_chain) {
 250                         item->ti_cb(item, item->ti_cb_data);
 251                 }
 252                 list_for_each(iter, &pinger_imports) {
 253                         struct obd_import *imp =
 254                                 list_entry(iter, struct obd_import,
 255                                                imp_pinger_chain);
 256
 257                         ptlrpc_pinger_process_import(imp, this_ping);
 258                         /* obd_timeout might have changed */
 259                         if (imp->imp_pingable && imp->imp_next_ping &&
 260                             cfs_time_after(imp->imp_next_ping,
 261                                            cfs_time_add(this_ping,
 262                                                         cfs_time_seconds(PING_INTERVAL))))
 263                                 ptlrpc_update_next_ping(imp, 0);
 264                 }
 265                 mutex_unlock(&pinger_mutex);
 266                 /* update memory usage info */
 267                 obd_update_maxusage();
 268
 269                 /* Wait until the next ping time, or until we're stopped. */
 270                 time_to_next_wake = pinger_check_timeout(this_ping);
 271                 /* The ping sent by ptlrpc_send_rpc may get sent out
 272                    say .01 second after this.
 273                    ptlrpc_pinger_sending_on_import will then set the
 274                    next ping time to next_ping + .01 sec, which means
 275                    we will SKIP the next ping at next_ping, and the
 276                    ping will get sent 2 timeouts from now!  Beware. */
 277                 CDEBUG(D_INFO, "next wakeup in "CFS_DURATION_T" ("
 278                        CFS_TIME_T")\n", time_to_next_wake,
 279                        cfs_time_add(this_ping,cfs_time_seconds(PING_INTERVAL)));
 280                 if (time_to_next_wake > 0) {
 281                         lwi = LWI_TIMEOUT(max_t(cfs_duration_t,
 282                                                 time_to_next_wake,
 283                                                 cfs_time_seconds(1)),
 284                                           NULL, NULL);
 285                         l_wait_event(thread->t_ctl_waitq,
 286                                      thread_is_stopping(thread) ||
 287                                      thread_is_event(thread),
 288                                      &lwi);
 289                         if (thread_test_and_clear_flags(thread, SVC_STOPPING)) {
 290                                 break;
 291                         } else {
 292                                 /* woken after adding import to reset timer */
 293                                 thread_test_and_clear_flags(thread, SVC_EVENT);
 294                         }
 295                 }
 296         }
 297
 298         thread_set_flags(thread, SVC_STOPPED);
 299         wake_up(&thread->t_ctl_waitq);
 300
 301         CDEBUG(D_NET, "pinger thread exiting, process %d\n", current_pid());
 302         return 0;
 303 }
 304
 305 static struct ptlrpc_thread pinger_thread;
 306
 307 int ptlrpc_start_pinger(void)
 308 {
 309         struct l_wait_info lwi = { 0 };
 310         int rc;
 311
 312         if (!thread_is_init(&pinger_thread) &&
 313             !thread_is_stopped(&pinger_thread))
 314                 return -EALREADY;
 315
 316         init_waitqueue_head(&pinger_thread.t_ctl_waitq);
 317
 318         strcpy(pinger_thread.t_name, "ll_ping");
 319
 320         /* CLONE_VM and CLONE_FILES just avoid a needless copy, because we
 321          * just drop the VM and FILES in cfs_daemonize_ctxt() right away. */
 322         rc = PTR_ERR(kthread_run(ptlrpc_pinger_main, &pinger_thread,
 323                                  "%s", pinger_thread.t_name));
 324         if (IS_ERR_VALUE(rc)) {
 325                 CERROR("cannot start thread: %d\n", rc);
 326                 return rc;
 327         }
 328         l_wait_event(pinger_thread.t_ctl_waitq,
 329                      thread_is_running(&pinger_thread), &lwi);
 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
 338         return 0;
 339 }
 340
 341 int ptlrpc_pinger_remove_timeouts(void);
 342
 343 int ptlrpc_stop_pinger(void)
 344 {
 345         struct l_wait_info lwi = { 0 };
 346         int rc = 0;
 347
 348         if (thread_is_init(&pinger_thread) ||
 349             thread_is_stopped(&pinger_thread))
 350                 return -EALREADY;
 351
 352         ptlrpc_pinger_remove_timeouts();
 353         thread_set_flags(&pinger_thread, SVC_STOPPING);
 354         wake_up(&pinger_thread.t_ctl_waitq);
 355
 356         l_wait_event(pinger_thread.t_ctl_waitq,
 357                      thread_is_stopped(&pinger_thread), &lwi);
 358
 359         return rc;
 360 }
 361
 362 void ptlrpc_pinger_sending_on_import(struct obd_import *imp)
 363 {
 364         ptlrpc_update_next_ping(imp, 0);
 365 }
 366 EXPORT_SYMBOL(ptlrpc_pinger_sending_on_import);
 367
 368 void ptlrpc_pinger_commit_expected(struct obd_import *imp)
 369 {
 370         ptlrpc_update_next_ping(imp, 1);
 371         LASSERT(spin_is_locked(&imp->imp_lock));
 372         /*
 373          * Avoid reading stale imp_connect_data.  When not sure if pings are
 374          * expected or not on next connection, we assume they are not and force
 375          * one anyway to guarantee the chance of updating
 376          * imp_peer_committed_transno.
 377          */
 378         if (imp->imp_state != LUSTRE_IMP_FULL ||
 379             OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS))
 380                 imp->imp_force_next_verify = 1;
 381 }
 382
 383 int ptlrpc_pinger_add_import(struct obd_import *imp)
 384 {
 385         if (!list_empty(&imp->imp_pinger_chain))
 386                 return -EALREADY;
 387
 388         mutex_lock(&pinger_mutex);
 389         CDEBUG(D_HA, "adding pingable import %s->%s\n",
 390                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 391         /* if we add to pinger we want recovery on this import */
 392         imp->imp_obd->obd_no_recov = 0;
 393         ptlrpc_update_next_ping(imp, 0);
 394         /* XXX sort, blah blah */
 395         list_add_tail(&imp->imp_pinger_chain, &pinger_imports);
 396         class_import_get(imp);
 397
 398         ptlrpc_pinger_wake_up();
 399         mutex_unlock(&pinger_mutex);
 400
 401         return 0;
 402 }
 403 EXPORT_SYMBOL(ptlrpc_pinger_add_import);
 404
 405 int ptlrpc_pinger_del_import(struct obd_import *imp)
 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 struct timeout_item* ptlrpc_new_timeout(int time, 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(int 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(int 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 != NULL, "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(void)
 540 {
 541         thread_add_flags(&pinger_thread, SVC_EVENT);
 542         wake_up(&pinger_thread.t_ctl_waitq);
 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 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         time_t expire_time;
 583
 584         unshare_fs_struct();
 585
 586         CDEBUG(D_HA, "Starting Ping Evictor\n");
 587         pet_state = PET_READY;
 588         while (1) {
 589                 l_wait_event(pet_waitq, (!list_empty(&pet_list)) ||
 590                              (pet_state == PET_TERMINATE), &lwi);
 591
 592                 /* loop until all obd's will be removed */
 593                 if ((pet_state == PET_TERMINATE) && list_empty(&pet_list))
 594                         break;
 595
 596                 /* we only get here if pet_exp != NULL, and the end of this
 597                  * loop is the only place which sets it NULL again, so lock
 598                  * is not strictly necessary. */
 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 = cfs_time_current_sec() - PING_EVICT_TIMEOUT;
 605
 606                 CDEBUG(D_HA, "evicting all exports of obd %s older than %ld\n",
 607                        obd->obd_name, expire_time);
 608
 609                 /* Exports can't be deleted out of the list while we hold
 610                  * the obd lock (class_unlink_export), which means we can't
 611                  * lose the last ref on the export.  If they've already been
 612                  * removed from the list, we won't find them here. */
 613                 spin_lock(&obd->obd_dev_lock);
 614                 while (!list_empty(&obd->obd_exports_timed)) {
 615                         exp = list_entry(obd->obd_exports_timed.next,
 616                                              struct obd_export,
 617                                              exp_obd_chain_timed);
 618                         if (expire_time > exp->exp_last_request_time) {
 619                                 class_export_get(exp);
 620                                 spin_unlock(&obd->obd_dev_lock);
 621                                 LCONSOLE_WARN("%s: haven't heard from client %s"
 622                                               " (at %s) in %ld seconds. I think"
 623                                               " it's dead, and I am evicting"
 624                                               " it. exp %p, cur %ld expire %ld"
 625                                               " last %ld\n",
 626                                               obd->obd_name,
 627                                               obd_uuid2str(&exp->exp_client_uuid),
 628                                               obd_export_nid2str(exp),
 629                                               (long)(cfs_time_current_sec() -
 630                                                      exp->exp_last_request_time),
 631                                               exp, (long)cfs_time_current_sec(),
 632                                               (long)expire_time,
 633                                               (long)exp->exp_last_request_time);
 634                                 CDEBUG(D_HA, "Last request was at %ld\n",
 635                                        exp->exp_last_request_time);
 636                                 class_fail_export(exp);
 637                                 class_export_put(exp);
 638                                 spin_lock(&obd->obd_dev_lock);
 639                         } else {
 640                                 /* List is sorted, so everyone below is ok */
 641                                 break;
 642                         }
 643                 }
 644                 spin_unlock(&obd->obd_dev_lock);
 645
 646                 spin_lock(&pet_lock);
 647                 list_del_init(&obd->obd_evict_list);
 648                 spin_unlock(&pet_lock);
 649
 650                 class_decref(obd, "evictor", obd);
 651         }
 652         CDEBUG(D_HA, "Exiting Ping Evictor\n");
 653
 654         return 0;
 655 }
 656
 657 void ping_evictor_start(void)
 658 {
 659         struct task_struct *task;
 660
 661         if (++pet_refcount > 1)
 662                 return;
 663
 664         init_waitqueue_head(&pet_waitq);
 665
 666         task = kthread_run(ping_evictor_main, NULL, "ll_evictor");
 667         if (IS_ERR(task)) {
 668                 pet_refcount--;
 669                 CERROR("Cannot start ping evictor thread: %ld\n",
 670                         PTR_ERR(task));
 671         }
 672 }
 673 EXPORT_SYMBOL(ping_evictor_start);
 674
 675 void ping_evictor_stop(void)
 676 {
 677         if (--pet_refcount > 0)
 678                 return;
 679
 680         pet_state = PET_TERMINATE;
 681         wake_up(&pet_waitq);
 682 }
 683 EXPORT_SYMBOL(ping_evictor_stop);