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 CFS_MODULE_PARM(suppress_pings, "i", int, 0644, "Suppress pings");
  49
  50 struct mutex pinger_mutex;
  51 static LIST_HEAD(pinger_imports);
  52 static struct list_head timeout_list = LIST_HEAD_INIT(timeout_list);
  53
  54 int ptlrpc_pinger_suppress_pings(void)
  55 {
  56         return suppress_pings;
  57 }
  58 EXPORT_SYMBOL(ptlrpc_pinger_suppress_pings);
  59
  60 struct ptlrpc_request *
  61 ptlrpc_prep_ping(struct obd_import *imp)
  62 {
  63         struct ptlrpc_request *req;
  64
  65         req = ptlrpc_request_alloc_pack(imp, &RQF_OBD_PING,
  66                                         LUSTRE_OBD_VERSION, OBD_PING);
  67         if (req) {
  68                 ptlrpc_request_set_replen(req);
  69                 req->rq_no_resend = req->rq_no_delay = 1;
  70         }
  71         return req;
  72 }
  73
  74 int ptlrpc_obd_ping(struct obd_device *obd)
  75 {
  76         int rc;
  77         struct ptlrpc_request *req;
  78
  79         req = ptlrpc_prep_ping(obd->u.cli.cl_import);
  80         if (req == NULL)
  81                 return -ENOMEM;
  82
  83         req->rq_send_state = LUSTRE_IMP_FULL;
  84
  85         rc = ptlrpc_queue_wait(req);
  86
  87         ptlrpc_req_finished(req);
  88
  89         return rc;
  90 }
  91 EXPORT_SYMBOL(ptlrpc_obd_ping);
  92
  93 int ptlrpc_ping(struct obd_import *imp)
  94 {
  95         struct ptlrpc_request *req;
  96
  97         req = ptlrpc_prep_ping(imp);
  98         if (req == NULL) {
  99                 CERROR("OOM trying to ping %s->%s\n",
 100                        imp->imp_obd->obd_uuid.uuid,
 101                        obd2cli_tgt(imp->imp_obd));
 102                 return -ENOMEM;
 103         }
 104
 105         DEBUG_REQ(D_INFO, req, "pinging %s->%s",
 106                   imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 107         ptlrpcd_add_req(req, PDL_POLICY_ROUND, -1);
 108
 109         return 0;
 110 }
 111
 112 void ptlrpc_update_next_ping(struct obd_import *imp, int soon)
 113 {
 114         int time = soon ? PING_INTERVAL_SHORT : PING_INTERVAL;
 115         if (imp->imp_state == LUSTRE_IMP_DISCON) {
 116                 int dtime = max_t(int, CONNECTION_SWITCH_MIN,
 117                                   AT_OFF ? 0 :
 118                                   at_get(&imp->imp_at.iat_net_latency));
 119                 time = min(time, dtime);
 120         }
 121         imp->imp_next_ping = cfs_time_shift(time);
 122 }
 123
 124 void ptlrpc_ping_import_soon(struct obd_import *imp)
 125 {
 126         imp->imp_next_ping = cfs_time_current();
 127 }
 128
 129 static inline int imp_is_deactive(struct obd_import *imp)
 130 {
 131         return (imp->imp_deactive ||
 132                 OBD_FAIL_CHECK(OBD_FAIL_PTLRPC_IMP_DEACTIVE));
 133 }
 134
 135 static inline int ptlrpc_next_reconnect(struct obd_import *imp)
 136 {
 137         if (imp->imp_server_timeout)
 138                 return cfs_time_shift(obd_timeout / 2);
 139         else
 140                 return cfs_time_shift(obd_timeout);
 141 }
 142
 143 static atomic_t suspend_timeouts = ATOMIC_INIT(0);
 144 static cfs_time_t suspend_wakeup_time = 0;
 145
 146 cfs_duration_t pinger_check_timeout(cfs_time_t time)
 147 {
 148         struct timeout_item *item;
 149         cfs_time_t timeout = PING_INTERVAL;
 150
 151         /* The timeout list is a increase order sorted list */
 152         mutex_lock(&pinger_mutex);
 153         list_for_each_entry(item, &timeout_list, ti_chain) {
 154                 int ti_timeout = item->ti_timeout;
 155                 if (timeout > ti_timeout)
 156                         timeout = ti_timeout;
 157                 break;
 158         }
 159         mutex_unlock(&pinger_mutex);
 160
 161         return cfs_time_sub(cfs_time_add(time, cfs_time_seconds(timeout)),
 162                                          cfs_time_current());
 163 }
 164
 165 static wait_queue_head_t suspend_timeouts_waitq;
 166
 167 cfs_time_t ptlrpc_suspend_wakeup_time(void)
 168 {
 169         return suspend_wakeup_time;
 170 }
 171
 172 void ptlrpc_deactivate_timeouts(struct obd_import *imp)
 173 {
 174         /*XXX: disabled for now, will be replaced by adaptive timeouts */
 175 #if 0
 176         if (imp->imp_no_timeout)
 177                 return;
 178         imp->imp_no_timeout = 1;
 179         atomic_inc(&suspend_timeouts);
 180         CDEBUG(D_HA|D_WARNING, "deactivate timeouts %u\n",
 181                atomic_read(&suspend_timeouts));
 182 #endif
 183 }
 184
 185 void ptlrpc_activate_timeouts(struct obd_import *imp)
 186 {
 187         /*XXX: disabled for now, will be replaced by adaptive timeouts */
 188 #if 0
 189         if (!imp->imp_no_timeout)
 190                 return;
 191         imp->imp_no_timeout = 0;
 192         LASSERT(atomic_read(&suspend_timeouts) > 0);
 193         if (atomic_dec_and_test(&suspend_timeouts)) {
 194                 suspend_wakeup_time = cfs_time_current();
 195                 wake_up(&suspend_timeouts_waitq);
 196         }
 197         CDEBUG(D_HA|D_WARNING, "activate timeouts %u\n",
 198                atomic_read(&suspend_timeouts));
 199 #endif
 200 }
 201
 202 int ptlrpc_check_suspend(void)
 203 {
 204         if (atomic_read(&suspend_timeouts))
 205                 return 1;
 206         return 0;
 207 }
 208
 209 int ptlrpc_check_and_wait_suspend(struct ptlrpc_request *req)
 210 {
 211         struct l_wait_info lwi;
 212
 213         if (atomic_read(&suspend_timeouts)) {
 214                 DEBUG_REQ(D_NET, req, "-- suspend %d regular timeout",
 215                           atomic_read(&suspend_timeouts));
 216                 lwi = LWI_INTR(NULL, NULL);
 217                 l_wait_event(suspend_timeouts_waitq,
 218                              atomic_read(&suspend_timeouts) == 0, &lwi);
 219                 DEBUG_REQ(D_NET, req, "-- recharge regular timeout");
 220                 return 1;
 221         }
 222         return 0;
 223 }
 224
 225
 226 static bool ir_up;
 227
 228 void ptlrpc_pinger_ir_up(void)
 229 {
 230         CDEBUG(D_HA, "IR up\n");
 231         ir_up = true;
 232 }
 233 EXPORT_SYMBOL(ptlrpc_pinger_ir_up);
 234
 235 void ptlrpc_pinger_ir_down(void)
 236 {
 237         CDEBUG(D_HA, "IR down\n");
 238         ir_up = false;
 239 }
 240 EXPORT_SYMBOL(ptlrpc_pinger_ir_down);
 241
 242 static void ptlrpc_pinger_process_import(struct obd_import *imp,
 243                                          unsigned long this_ping)
 244 {
 245         int level;
 246         int force;
 247         int force_next;
 248         int suppress;
 249
 250         spin_lock(&imp->imp_lock);
 251
 252         level = imp->imp_state;
 253         force = imp->imp_force_verify;
 254         force_next = imp->imp_force_next_verify;
 255         /*
 256          * This will be used below only if the import is "FULL".
 257          */
 258         suppress = ir_up && OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS);
 259
 260         imp->imp_force_verify = 0;
 261
 262         if (cfs_time_aftereq(imp->imp_next_ping - 5 * CFS_TICK, this_ping) &&
 263             !force) {
 264                 spin_unlock(&imp->imp_lock);
 265                 return;
 266         }
 267
 268         imp->imp_force_next_verify = 0;
 269
 270         spin_unlock(&imp->imp_lock);
 271
 272         CDEBUG(level == LUSTRE_IMP_FULL ? D_INFO : D_HA, "%s->%s: level %s/%u "
 273                "force %u force_next %u deactive %u pingable %u suppress %u\n",
 274                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 275                ptlrpc_import_state_name(level), level, force, force_next,
 276                imp->imp_deactive, imp->imp_pingable, suppress);
 277
 278         if (level == LUSTRE_IMP_DISCON && !imp_is_deactive(imp)) {
 279                 /* wait for a while before trying recovery again */
 280                 imp->imp_next_ping = ptlrpc_next_reconnect(imp);
 281                 if (!imp->imp_no_pinger_recover)
 282                         ptlrpc_initiate_recovery(imp);
 283         } else if (level != LUSTRE_IMP_FULL ||
 284                    imp->imp_obd->obd_no_recov ||
 285                    imp_is_deactive(imp)) {
 286                 CDEBUG(D_HA, "%s->%s: not pinging (in recovery "
 287                        "or recovery disabled: %s)\n",
 288                        imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd),
 289                        ptlrpc_import_state_name(level));
 290         } else if ((imp->imp_pingable && !suppress) || force_next || force) {
 291                 ptlrpc_ping(imp);
 292         }
 293 }
 294
 295 static int ptlrpc_pinger_main(void *arg)
 296 {
 297         struct ptlrpc_thread *thread = (struct ptlrpc_thread *)arg;
 298
 299         /* Record that the thread is running */
 300         thread_set_flags(thread, SVC_RUNNING);
 301         wake_up(&thread->t_ctl_waitq);
 302
 303         /* And now, loop forever, pinging as needed. */
 304         while (1) {
 305                 cfs_time_t this_ping = cfs_time_current();
 306                 struct l_wait_info lwi;
 307                 cfs_duration_t time_to_next_wake;
 308                 struct timeout_item *item;
 309                 struct list_head *iter;
 310
 311                 mutex_lock(&pinger_mutex);
 312                 list_for_each_entry(item, &timeout_list, ti_chain) {
 313                         item->ti_cb(item, item->ti_cb_data);
 314                 }
 315                 list_for_each(iter, &pinger_imports) {
 316                         struct obd_import *imp =
 317                                 list_entry(iter, struct obd_import,
 318                                                imp_pinger_chain);
 319
 320                         ptlrpc_pinger_process_import(imp, this_ping);
 321                         /* obd_timeout might have changed */
 322                         if (imp->imp_pingable && imp->imp_next_ping &&
 323                             cfs_time_after(imp->imp_next_ping,
 324                                            cfs_time_add(this_ping,
 325                                                         cfs_time_seconds(PING_INTERVAL))))
 326                                 ptlrpc_update_next_ping(imp, 0);
 327                 }
 328                 mutex_unlock(&pinger_mutex);
 329                 /* update memory usage info */
 330                 obd_update_maxusage();
 331
 332                 /* Wait until the next ping time, or until we're stopped. */
 333                 time_to_next_wake = pinger_check_timeout(this_ping);
 334                 /* The ping sent by ptlrpc_send_rpc may get sent out
 335                    say .01 second after this.
 336                    ptlrpc_pinger_sending_on_import will then set the
 337                    next ping time to next_ping + .01 sec, which means
 338                    we will SKIP the next ping at next_ping, and the
 339                    ping will get sent 2 timeouts from now!  Beware. */
 340                 CDEBUG(D_INFO, "next wakeup in "CFS_DURATION_T" ("
 341                        CFS_TIME_T")\n", time_to_next_wake,
 342                        cfs_time_add(this_ping,cfs_time_seconds(PING_INTERVAL)));
 343                 if (time_to_next_wake > 0) {
 344                         lwi = LWI_TIMEOUT(max_t(cfs_duration_t,
 345                                                 time_to_next_wake,
 346                                                 cfs_time_seconds(1)),
 347                                           NULL, NULL);
 348                         l_wait_event(thread->t_ctl_waitq,
 349                                      thread_is_stopping(thread) ||
 350                                      thread_is_event(thread),
 351                                      &lwi);
 352                         if (thread_test_and_clear_flags(thread, SVC_STOPPING)) {
 353                                 break;
 354                         } else {
 355                                 /* woken after adding import to reset timer */
 356                                 thread_test_and_clear_flags(thread, SVC_EVENT);
 357                         }
 358                 }
 359         }
 360
 361         thread_set_flags(thread, SVC_STOPPED);
 362         wake_up(&thread->t_ctl_waitq);
 363
 364         CDEBUG(D_NET, "pinger thread exiting, process %d\n", current_pid());
 365         return 0;
 366 }
 367
 368 static struct ptlrpc_thread pinger_thread;
 369
 370 int ptlrpc_start_pinger(void)
 371 {
 372         struct l_wait_info lwi = { 0 };
 373         int rc;
 374
 375         if (!thread_is_init(&pinger_thread) &&
 376             !thread_is_stopped(&pinger_thread))
 377                 return -EALREADY;
 378
 379         init_waitqueue_head(&pinger_thread.t_ctl_waitq);
 380         init_waitqueue_head(&suspend_timeouts_waitq);
 381
 382         strcpy(pinger_thread.t_name, "ll_ping");
 383
 384         /* CLONE_VM and CLONE_FILES just avoid a needless copy, because we
 385          * just drop the VM and FILES in cfs_daemonize_ctxt() right away. */
 386         rc = PTR_ERR(kthread_run(ptlrpc_pinger_main, &pinger_thread,
 387                                  "%s", pinger_thread.t_name));
 388         if (IS_ERR_VALUE(rc)) {
 389                 CERROR("cannot start thread: %d\n", rc);
 390                 return rc;
 391         }
 392         l_wait_event(pinger_thread.t_ctl_waitq,
 393                      thread_is_running(&pinger_thread), &lwi);
 394
 395         if (suppress_pings)
 396                 CWARN("Pings will be suppressed at the request of the "
 397                       "administrator.  The configuration shall meet the "
 398                       "additional requirements described in the manual.  "
 399                       "(Search for the \"suppress_pings\" kernel module "
 400                       "parameter.)\n");
 401
 402         return 0;
 403 }
 404
 405 int ptlrpc_pinger_remove_timeouts(void);
 406
 407 int ptlrpc_stop_pinger(void)
 408 {
 409         struct l_wait_info lwi = { 0 };
 410         int rc = 0;
 411
 412         if (thread_is_init(&pinger_thread) ||
 413             thread_is_stopped(&pinger_thread))
 414                 return -EALREADY;
 415
 416         ptlrpc_pinger_remove_timeouts();
 417         thread_set_flags(&pinger_thread, SVC_STOPPING);
 418         wake_up(&pinger_thread.t_ctl_waitq);
 419
 420         l_wait_event(pinger_thread.t_ctl_waitq,
 421                      thread_is_stopped(&pinger_thread), &lwi);
 422
 423         return rc;
 424 }
 425
 426 void ptlrpc_pinger_sending_on_import(struct obd_import *imp)
 427 {
 428         ptlrpc_update_next_ping(imp, 0);
 429 }
 430 EXPORT_SYMBOL(ptlrpc_pinger_sending_on_import);
 431
 432 void ptlrpc_pinger_commit_expected(struct obd_import *imp)
 433 {
 434         ptlrpc_update_next_ping(imp, 1);
 435         LASSERT(spin_is_locked(&imp->imp_lock));
 436         /*
 437          * Avoid reading stale imp_connect_data.  When not sure if pings are
 438          * expected or not on next connection, we assume they are not and force
 439          * one anyway to guarantee the chance of updating
 440          * imp_peer_committed_transno.
 441          */
 442         if (imp->imp_state != LUSTRE_IMP_FULL ||
 443             OCD_HAS_FLAG(&imp->imp_connect_data, PINGLESS))
 444                 imp->imp_force_next_verify = 1;
 445 }
 446
 447 int ptlrpc_pinger_add_import(struct obd_import *imp)
 448 {
 449         if (!list_empty(&imp->imp_pinger_chain))
 450                 return -EALREADY;
 451
 452         mutex_lock(&pinger_mutex);
 453         CDEBUG(D_HA, "adding pingable import %s->%s\n",
 454                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 455         /* if we add to pinger we want recovery on this import */
 456         imp->imp_obd->obd_no_recov = 0;
 457         ptlrpc_update_next_ping(imp, 0);
 458         /* XXX sort, blah blah */
 459         list_add_tail(&imp->imp_pinger_chain, &pinger_imports);
 460         class_import_get(imp);
 461
 462         ptlrpc_pinger_wake_up();
 463         mutex_unlock(&pinger_mutex);
 464
 465         return 0;
 466 }
 467 EXPORT_SYMBOL(ptlrpc_pinger_add_import);
 468
 469 int ptlrpc_pinger_del_import(struct obd_import *imp)
 470 {
 471         if (list_empty(&imp->imp_pinger_chain))
 472                 return -ENOENT;
 473
 474         mutex_lock(&pinger_mutex);
 475         list_del_init(&imp->imp_pinger_chain);
 476         CDEBUG(D_HA, "removing pingable import %s->%s\n",
 477                imp->imp_obd->obd_uuid.uuid, obd2cli_tgt(imp->imp_obd));
 478         /* if we remove from pinger we don't want recovery on this import */
 479         imp->imp_obd->obd_no_recov = 1;
 480         class_import_put(imp);
 481         mutex_unlock(&pinger_mutex);
 482         return 0;
 483 }
 484 EXPORT_SYMBOL(ptlrpc_pinger_del_import);
 485
 486 /**
 487  * Register a timeout callback to the pinger list, and the callback will
 488  * be called when timeout happens.
 489  */
 490 struct timeout_item* ptlrpc_new_timeout(int time, enum timeout_event event,
 491                                         timeout_cb_t cb, void *data)
 492 {
 493         struct timeout_item *ti;
 494
 495         OBD_ALLOC_PTR(ti);
 496         if (!ti)
 497                 return(NULL);
 498
 499         INIT_LIST_HEAD(&ti->ti_obd_list);
 500         INIT_LIST_HEAD(&ti->ti_chain);
 501         ti->ti_timeout = time;
 502         ti->ti_event = event;
 503         ti->ti_cb = cb;
 504         ti->ti_cb_data = data;
 505
 506         return ti;
 507 }
 508
 509 /**
 510  * Register timeout event on the the pinger thread.
 511  * Note: the timeout list is an sorted list with increased timeout value.
 512  */
 513 static struct timeout_item*
 514 ptlrpc_pinger_register_timeout(int time, enum timeout_event event,
 515                                timeout_cb_t cb, void *data)
 516 {
 517         struct timeout_item *item, *tmp;
 518
 519         LASSERT(mutex_is_locked(&pinger_mutex));
 520
 521         list_for_each_entry(item, &timeout_list, ti_chain)
 522                 if (item->ti_event == event)
 523                         goto out;
 524
 525         item = ptlrpc_new_timeout(time, event, cb, data);
 526         if (item) {
 527                 list_for_each_entry_reverse(tmp, &timeout_list, ti_chain) {
 528                         if (tmp->ti_timeout < time) {
 529                                 list_add(&item->ti_chain, &tmp->ti_chain);
 530                                 goto out;
 531                         }
 532                 }
 533                 list_add(&item->ti_chain, &timeout_list);
 534         }
 535 out:
 536         return item;
 537 }
 538
 539 /* Add a client_obd to the timeout event list, when timeout(@time)
 540  * happens, the callback(@cb) will be called.
 541  */
 542 int ptlrpc_add_timeout_client(int time, enum timeout_event event,
 543                               timeout_cb_t cb, void *data,
 544                               struct list_head *obd_list)
 545 {
 546         struct timeout_item *ti;
 547
 548         mutex_lock(&pinger_mutex);
 549         ti = ptlrpc_pinger_register_timeout(time, event, cb, data);
 550         if (!ti) {
 551                 mutex_unlock(&pinger_mutex);
 552                 return (-EINVAL);
 553         }
 554         list_add(obd_list, &ti->ti_obd_list);
 555         mutex_unlock(&pinger_mutex);
 556         return 0;
 557 }
 558 EXPORT_SYMBOL(ptlrpc_add_timeout_client);
 559
 560 int ptlrpc_del_timeout_client(struct list_head *obd_list,
 561                               enum timeout_event event)
 562 {
 563         struct timeout_item *ti = NULL, *item;
 564
 565         if (list_empty(obd_list))
 566                 return 0;
 567         mutex_lock(&pinger_mutex);
 568         list_del_init(obd_list);
 569         /**
 570          * If there are no obd attached to the timeout event
 571          * list, remove this timeout event from the pinger
 572          */
 573         list_for_each_entry(item, &timeout_list, ti_chain) {
 574                 if (item->ti_event == event) {
 575                         ti = item;
 576                         break;
 577                 }
 578         }
 579         LASSERTF(ti != NULL, "ti is NULL ! \n");
 580         if (list_empty(&ti->ti_obd_list)) {
 581                 list_del(&ti->ti_chain);
 582                 OBD_FREE_PTR(ti);
 583         }
 584         mutex_unlock(&pinger_mutex);
 585         return 0;
 586 }
 587 EXPORT_SYMBOL(ptlrpc_del_timeout_client);
 588
 589 int ptlrpc_pinger_remove_timeouts(void)
 590 {
 591         struct timeout_item *item, *tmp;
 592
 593         mutex_lock(&pinger_mutex);
 594         list_for_each_entry_safe(item, tmp, &timeout_list, ti_chain) {
 595                 LASSERT(list_empty(&item->ti_obd_list));
 596                 list_del(&item->ti_chain);
 597                 OBD_FREE_PTR(item);
 598         }
 599         mutex_unlock(&pinger_mutex);
 600         return 0;
 601 }
 602
 603 void ptlrpc_pinger_wake_up(void)
 604 {
 605         thread_add_flags(&pinger_thread, SVC_EVENT);
 606         wake_up(&pinger_thread.t_ctl_waitq);
 607 }
 608
 609 /* Ping evictor thread */
 610 #define PET_READY     1
 611 #define PET_TERMINATE 2
 612
 613 static int             pet_refcount = 0;
 614 static int             pet_state;
 615 static wait_queue_head_t       pet_waitq;
 616 LIST_HEAD(pet_list);
 617 static DEFINE_SPINLOCK(pet_lock);
 618
 619 int ping_evictor_wake(struct obd_export *exp)
 620 {
 621         struct obd_device *obd;
 622
 623         spin_lock(&pet_lock);
 624         if (pet_state != PET_READY) {
 625                 /* eventually the new obd will call here again. */
 626                 spin_unlock(&pet_lock);
 627                 return 1;
 628         }
 629
 630         obd = class_exp2obd(exp);
 631         if (list_empty(&obd->obd_evict_list)) {
 632                 class_incref(obd, "evictor", obd);
 633                 list_add(&obd->obd_evict_list, &pet_list);
 634         }
 635         spin_unlock(&pet_lock);
 636
 637         wake_up(&pet_waitq);
 638         return 0;
 639 }
 640
 641 static int ping_evictor_main(void *arg)
 642 {
 643         struct obd_device *obd;
 644         struct obd_export *exp;
 645         struct l_wait_info lwi = { 0 };
 646         time_t expire_time;
 647
 648         unshare_fs_struct();
 649
 650         CDEBUG(D_HA, "Starting Ping Evictor\n");
 651         pet_state = PET_READY;
 652         while (1) {
 653                 l_wait_event(pet_waitq, (!list_empty(&pet_list)) ||
 654                              (pet_state == PET_TERMINATE), &lwi);
 655
 656                 /* loop until all obd's will be removed */
 657                 if ((pet_state == PET_TERMINATE) && list_empty(&pet_list))
 658                         break;
 659
 660                 /* we only get here if pet_exp != NULL, and the end of this
 661                  * loop is the only place which sets it NULL again, so lock
 662                  * is not strictly necessary. */
 663                 spin_lock(&pet_lock);
 664                 obd = list_entry(pet_list.next, struct obd_device,
 665                                      obd_evict_list);
 666                 spin_unlock(&pet_lock);
 667
 668                 expire_time = cfs_time_current_sec() - PING_EVICT_TIMEOUT;
 669
 670                 CDEBUG(D_HA, "evicting all exports of obd %s older than %ld\n",
 671                        obd->obd_name, expire_time);
 672
 673                 /* Exports can't be deleted out of the list while we hold
 674                  * the obd lock (class_unlink_export), which means we can't
 675                  * lose the last ref on the export.  If they've already been
 676                  * removed from the list, we won't find them here. */
 677                 spin_lock(&obd->obd_dev_lock);
 678                 while (!list_empty(&obd->obd_exports_timed)) {
 679                         exp = list_entry(obd->obd_exports_timed.next,
 680                                              struct obd_export,
 681                                              exp_obd_chain_timed);
 682                         if (expire_time > exp->exp_last_request_time) {
 683                                 class_export_get(exp);
 684                                 spin_unlock(&obd->obd_dev_lock);
 685                                 LCONSOLE_WARN("%s: haven't heard from client %s"
 686                                               " (at %s) in %ld seconds. I think"
 687                                               " it's dead, and I am evicting"
 688                                               " it. exp %p, cur %ld expire %ld"
 689                                               " last %ld\n",
 690                                               obd->obd_name,
 691                                               obd_uuid2str(&exp->exp_client_uuid),
 692                                               obd_export_nid2str(exp),
 693                                               (long)(cfs_time_current_sec() -
 694                                                      exp->exp_last_request_time),
 695                                               exp, (long)cfs_time_current_sec(),
 696                                               (long)expire_time,
 697                                               (long)exp->exp_last_request_time);
 698                                 CDEBUG(D_HA, "Last request was at %ld\n",
 699                                        exp->exp_last_request_time);
 700                                 class_fail_export(exp);
 701                                 class_export_put(exp);
 702                                 spin_lock(&obd->obd_dev_lock);
 703                         } else {
 704                                 /* List is sorted, so everyone below is ok */
 705                                 break;
 706                         }
 707                 }
 708                 spin_unlock(&obd->obd_dev_lock);
 709
 710                 spin_lock(&pet_lock);
 711                 list_del_init(&obd->obd_evict_list);
 712                 spin_unlock(&pet_lock);
 713
 714                 class_decref(obd, "evictor", obd);
 715         }
 716         CDEBUG(D_HA, "Exiting Ping Evictor\n");
 717
 718         return 0;
 719 }
 720
 721 void ping_evictor_start(void)
 722 {
 723         struct task_struct *task;
 724
 725         if (++pet_refcount > 1)
 726                 return;
 727
 728         init_waitqueue_head(&pet_waitq);
 729
 730         task = kthread_run(ping_evictor_main, NULL, "ll_evictor");
 731         if (IS_ERR(task)) {
 732                 pet_refcount--;
 733                 CERROR("Cannot start ping evictor thread: %ld\n",
 734                         PTR_ERR(task));
 735         }
 736 }
 737 EXPORT_SYMBOL(ping_evictor_start);
 738
 739 void ping_evictor_stop(void)
 740 {
 741         if (--pet_refcount > 0)
 742                 return;
 743
 744         pet_state = PET_TERMINATE;
 745         wake_up(&pet_waitq);
 746 }
 747 EXPORT_SYMBOL(ping_evictor_stop);