lustre/quota/qsd_writeback.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, write to the
  18  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19  * Boston, MA 021110-1307, USA
  20  *
  21  * GPL HEADER END
  22  */
  23 /*
  24  * Copyright (c) 2012, 2017, Intel Corporation.
  25  * Use is subject to license terms.
  26  *
  27  * Author: Johann Lombardi <johann.lombardi@intel.com>
  28  * Author: Niu    Yawei    <yawei.niu@intel.com>
  29  */
  30
  31 #define DEBUG_SUBSYSTEM S_LQUOTA
  32
  33 #include <linux/kthread.h>
  34 #include "qsd_internal.h"
  35
  36 /*
  37  * Allocate and fill an qsd_upd_rec structure to be processed by the writeback
  38  * thread.
  39  *
  40  * \param qqi - is the qsd_qtype_info structure relevant to the update
  41  * \param lqe - is the lquota entry subject to the update
  42  * \param qid - is the identifier subject to the update
  43  * \param rec - is the record storing the new quota settings
  44  * \param ver - is the version associated with the update
  45  * \param global - is a boolean set to true if this is an update of the global
  46  *                 index and false for a slave index.
  47  */
  48 static struct qsd_upd_rec *qsd_upd_alloc(struct qsd_qtype_info *qqi,
  49                                          struct lquota_entry *lqe,
  50                                          union lquota_id *qid,
  51                                          union lquota_rec *rec, __u64 ver,
  52                                          bool global)
  53 {
  54         struct qsd_upd_rec      *upd;
  55
  56         OBD_SLAB_ALLOC_PTR_GFP(upd, upd_kmem, GFP_NOFS);
  57         if (upd == NULL) {
  58                 return NULL;
  59         }
  60
  61         /* fill it */
  62         INIT_LIST_HEAD(&upd->qur_link);
  63         upd->qur_qqi = qqi;
  64         upd->qur_lqe = lqe;
  65         if (lqe)
  66                 lqe_getref(lqe);
  67         upd->qur_qid    = *qid;
  68         upd->qur_rec    = *rec;
  69         upd->qur_ver    = ver;
  70         upd->qur_global = global;
  71
  72         return upd;
  73 }
  74
  75 static void qsd_upd_free(struct qsd_upd_rec *upd)
  76 {
  77         if (upd->qur_lqe)
  78                 lqe_putref(upd->qur_lqe);
  79         OBD_SLAB_FREE_PTR(upd, upd_kmem);
  80 }
  81
  82 /* must hold the qsd_lock */
  83 static void qsd_upd_add(struct qsd_instance *qsd, struct qsd_upd_rec *upd)
  84 {
  85         if (!qsd->qsd_stopping) {
  86                 list_add_tail(&upd->qur_link, &qsd->qsd_upd_list);
  87                 /* wake up the upd thread */
  88                 if (qsd->qsd_upd_task)
  89                         wake_up_process(qsd->qsd_upd_task);
  90         } else {
  91                 CWARN("%s: discard update.\n", qsd->qsd_svname);
  92                 if (upd->qur_lqe)
  93                         LQUOTA_WARN(upd->qur_lqe, "discard update.");
  94                 qsd_upd_free(upd);
  95         }
  96 }
  97
  98 /* must hold the qsd_lock */
  99 static void qsd_add_deferred(struct qsd_instance *qsd, struct list_head *list,
 100                              struct qsd_upd_rec *upd)
 101 {
 102         struct qsd_upd_rec      *tmp, *n;
 103
 104         if (qsd->qsd_stopping) {
 105                 CWARN("%s: discard deferred udpate.\n", qsd->qsd_svname);
 106                 if (upd->qur_lqe)
 107                         LQUOTA_WARN(upd->qur_lqe, "discard deferred update.");
 108                 qsd_upd_free(upd);
 109                 return;
 110         }
 111
 112         /* Sort the updates in ascending order */
 113         list_for_each_entry_safe_reverse(tmp, n, list, qur_link) {
 114
 115                 /* There could be some legacy records which have duplicated
 116                  * version. Imagine following scenario: slave received global
 117                  * glimpse and queued a record in the deferred list, then
 118                  * master crash and rollback to an ealier version, then the
 119                  * version of queued record will be conflicting with later
 120                  * updates. We should just delete the legacy record in such
 121                  * case. */
 122                 if (upd->qur_ver == tmp->qur_ver) {
 123                         if (tmp->qur_lqe)
 124                                 LQUOTA_WARN(tmp->qur_lqe, "Found a conflict "
 125                                             "record with ver:%llu",
 126                                             tmp->qur_ver);
 127                         else
 128                                 CWARN("%s: Found a conflict record with ver: "
 129                                       "%llu\n", qsd->qsd_svname, tmp->qur_ver);
 130
 131                         list_del_init(&tmp->qur_link);
 132                         qsd_upd_free(tmp);
 133                 } else if (upd->qur_ver < tmp->qur_ver) {
 134                         continue;
 135                 } else {
 136                         list_add_tail(&upd->qur_link, &tmp->qur_link);
 137                         return;
 138                 }
 139         }
 140         list_add(&upd->qur_link, list);
 141 }
 142
 143 /* must hold the qsd_lock */
 144 static void qsd_kickoff_deferred(struct qsd_qtype_info *qqi,
 145                                  struct list_head *list, __u64 ver)
 146 {
 147         struct qsd_upd_rec      *upd, *tmp;
 148         ENTRY;
 149
 150         /* Get the first update record in the list, which has the smallest
 151          * version, discard all records with versions smaller than the current
 152          * one */
 153         list_for_each_entry_safe(upd, tmp, list, qur_link) {
 154                 if (upd->qur_ver <= ver) {
 155                         /* drop this update */
 156                         list_del_init(&upd->qur_link);
 157                         CDEBUG(D_QUOTA, "%s: skipping deferred update ver:"
 158                                "%llu/%llu, global:%d, qid:%llu\n",
 159                                qqi->qqi_qsd->qsd_svname, upd->qur_ver, ver,
 160                                upd->qur_global, upd->qur_qid.qid_uid);
 161                         qsd_upd_free(upd);
 162                 } else {
 163                         break;
 164                 }
 165         }
 166
 167         /* No remaining deferred update */
 168         if (list_empty(list))
 169                 RETURN_EXIT;
 170
 171         CDEBUG(D_QUOTA, "%s: found deferred update record. "
 172                "version:%llu/%llu, global:%d, qid:%llu\n",
 173                qqi->qqi_qsd->qsd_svname, upd->qur_ver, ver,
 174                upd->qur_global, upd->qur_qid.qid_uid);
 175
 176         LASSERTF(upd->qur_ver > ver, "lur_ver:%llu, cur_ver:%llu\n",
 177                  upd->qur_ver, ver);
 178
 179         /* Kick off the deferred udpate */
 180         if (upd->qur_ver == ver + 1) {
 181                 list_del_init(&upd->qur_link);
 182                 qsd_upd_add(qqi->qqi_qsd, upd);
 183         }
 184         EXIT;
 185 }
 186
 187 /* Bump version of global or slave index copy
 188  *
 189  * \param qqi    - qsd_qtype_info
 190  * \param ver    - version to be bumped to
 191  * \param global - global or slave index copy?
 192  */
 193 void qsd_bump_version(struct qsd_qtype_info *qqi, __u64 ver, bool global)
 194 {
 195         struct list_head *list;
 196         __u64            *idx_ver;
 197
 198         idx_ver = global ? &qqi->qqi_glb_ver : &qqi->qqi_slv_ver;
 199         list    = global ? &qqi->qqi_deferred_glb : &qqi->qqi_deferred_slv;
 200
 201         write_lock(&qqi->qqi_qsd->qsd_lock);
 202         *idx_ver = ver;
 203         if (global)
 204                 qqi->qqi_glb_uptodate = 1;
 205         else
 206                 qqi->qqi_slv_uptodate = 1;
 207         qsd_kickoff_deferred(qqi, list, ver);
 208         write_unlock(&qqi->qqi_qsd->qsd_lock);
 209 }
 210
 211 /*
 212  * Schedule a commit of a lquota entry
 213  *
 214  * \param  qqi   - qsd_qtype_info
 215  * \param  lqe   - lquota_entry
 216  * \param  qid   - quota id
 217  * \param  rec   - global or slave record to be updated to disk
 218  * \param  ver   - new index file version
 219  * \param  global- true: master record; false: slave record
 220  */
 221 void qsd_upd_schedule(struct qsd_qtype_info *qqi, struct lquota_entry *lqe,
 222                       union lquota_id *qid, union lquota_rec *rec, __u64 ver,
 223                       bool global)
 224 {
 225         struct qsd_upd_rec      *upd;
 226         struct qsd_instance     *qsd = qqi->qqi_qsd;
 227         __u64                    cur_ver;
 228         ENTRY;
 229
 230         CDEBUG(D_QUOTA, "%s: schedule update. global:%s, version:%llu\n",
 231                qsd->qsd_svname, global ? "true" : "false", ver);
 232
 233         upd = qsd_upd_alloc(qqi, lqe, qid, rec, ver, global);
 234         if (upd == NULL)
 235                 RETURN_EXIT;
 236
 237         /* If we don't want update index version, no need to sort the
 238          * records in version order, just schedule the updates instantly. */
 239         if (ver == 0) {
 240                 write_lock(&qsd->qsd_lock);
 241                 qsd_upd_add(qsd, upd);
 242                 write_unlock(&qsd->qsd_lock);
 243                 RETURN_EXIT;
 244         }
 245
 246         write_lock(&qsd->qsd_lock);
 247
 248         cur_ver = global ? qqi->qqi_glb_ver : qqi->qqi_slv_ver;
 249
 250         if (ver <= cur_ver) {
 251                 if (global)
 252                         /* legitimate race between glimpse AST and
 253                          * reintegration */
 254                         CDEBUG(D_QUOTA, "%s: discarding glb update from glimpse"
 255                                " ver:%llu local ver:%llu\n",
 256                                qsd->qsd_svname, ver, cur_ver);
 257                 else
 258                         CERROR("%s: discard slv update, ver:%llu local ver:"
 259                                "%llu\n", qsd->qsd_svname, ver, cur_ver);
 260                 qsd_upd_free(upd);
 261         } else if ((ver == cur_ver + 1) && qqi->qqi_glb_uptodate &&
 262                    qqi->qqi_slv_uptodate) {
 263                 /* In order update, and reintegration has been done. */
 264                 qsd_upd_add(qsd, upd);
 265         } else {
 266                 /* Out of order update (the one with smaller version hasn't
 267                  * reached slave or hasn't been flushed to disk yet), or
 268                  * the reintegration is in progress. Defer the update. */
 269                 struct list_head *list = global ? &qqi->qqi_deferred_glb :
 270                                                   &qqi->qqi_deferred_slv;
 271                 qsd_add_deferred(qsd, list, upd);
 272         }
 273
 274         write_unlock(&qsd->qsd_lock);
 275
 276         EXIT;
 277 }
 278
 279 static int qsd_process_upd(const struct lu_env *env, struct qsd_upd_rec *upd)
 280 {
 281         struct lquota_entry     *lqe = upd->qur_lqe;
 282         struct qsd_qtype_info   *qqi = upd->qur_qqi;
 283         int                      rc;
 284         ENTRY;
 285
 286         if (lqe == NULL) {
 287                 lqe = lqe_locate(env, qqi->qqi_site, &upd->qur_qid);
 288                 if (IS_ERR(lqe))
 289                         GOTO(out, rc = PTR_ERR(lqe));
 290         }
 291
 292         /* The in-memory lqe update for slave index copy isn't deferred,
 293          * we shouldn't touch it here. */
 294         if (upd->qur_global) {
 295                 rc = qsd_update_lqe(env, lqe, upd->qur_global, &upd->qur_rec);
 296                 if (rc)
 297                         GOTO(out, rc);
 298                 /* refresh usage */
 299                 qsd_refresh_usage(env, lqe);
 300
 301                 spin_lock(&qqi->qqi_qsd->qsd_adjust_lock);
 302                 lqe->lqe_adjust_time = 0;
 303                 spin_unlock(&qqi->qqi_qsd->qsd_adjust_lock);
 304
 305                 /* Report usage asynchronously */
 306                 rc = qsd_adjust(env, lqe);
 307                 if (rc)
 308                         LQUOTA_ERROR(lqe, "failed to report usage, rc:%d", rc);
 309         }
 310
 311         rc = qsd_update_index(env, qqi, &upd->qur_qid, upd->qur_global,
 312                               upd->qur_ver, &upd->qur_rec);
 313 out:
 314         if (upd->qur_global && rc == 0 &&
 315             upd->qur_rec.lqr_glb_rec.qbr_softlimit == 0 &&
 316             upd->qur_rec.lqr_glb_rec.qbr_hardlimit == 0 &&
 317             (LQUOTA_FLAG(upd->qur_rec.lqr_glb_rec.qbr_time) &
 318                                                         LQUOTA_FLAG_DEFAULT)) {
 319                 lqe->lqe_is_default = true;
 320                 if (qqi->qqi_default_softlimit == 0 &&
 321                     qqi->qqi_default_hardlimit == 0)
 322                         lqe->lqe_enforced = false;
 323                 else
 324                         lqe->lqe_enforced = true;
 325
 326                 LQUOTA_DEBUG(lqe, "update to use default quota");
 327         }
 328
 329         if (lqe && !IS_ERR(lqe)) {
 330                 lqe_putref(lqe);
 331                 upd->qur_lqe = NULL;
 332         }
 333         RETURN(rc);
 334 }
 335
 336 void qsd_adjust_schedule(struct lquota_entry *lqe, bool defer, bool cancel)
 337 {
 338         struct qsd_instance     *qsd = lqe2qqi(lqe)->qqi_qsd;
 339         bool                     added = false;
 340
 341         read_lock(&qsd->qsd_lock);
 342         if (qsd->qsd_stopping) {
 343                 read_unlock(&qsd->qsd_lock);
 344                 return;
 345         }
 346         read_unlock(&qsd->qsd_lock);
 347
 348         lqe_getref(lqe);
 349         spin_lock(&qsd->qsd_adjust_lock);
 350
 351         /* the lqe is being queued for the per-ID lock cancel, we should
 352          * cancel the lock cancel and re-add it for quota adjust */
 353         if (!list_empty(&lqe->lqe_link) &&
 354             lqe->lqe_adjust_time == 0) {
 355                 list_del_init(&lqe->lqe_link);
 356                 lqe_putref(lqe);
 357         }
 358
 359         if (list_empty(&lqe->lqe_link)) {
 360                 if (!cancel) {
 361                         lqe->lqe_adjust_time = ktime_get_seconds();
 362                         if (defer)
 363                                 lqe->lqe_adjust_time += QSD_WB_INTERVAL;
 364                 } else {
 365                         lqe->lqe_adjust_time = 0;
 366                 }
 367
 368                 /* lqe reference transferred to list */
 369                 if (defer)
 370                         list_add_tail(&lqe->lqe_link,
 371                                           &qsd->qsd_adjust_list);
 372                 else
 373                         list_add(&lqe->lqe_link, &qsd->qsd_adjust_list);
 374                 added = true;
 375         }
 376         spin_unlock(&qsd->qsd_adjust_lock);
 377
 378         if (!added)
 379                 lqe_putref(lqe);
 380         else {
 381                 read_lock(&qsd->qsd_lock);
 382                 if (qsd->qsd_upd_task)
 383                         wake_up_process(qsd->qsd_upd_task);
 384                 read_unlock(&qsd->qsd_lock);
 385         }
 386 }
 387
 388 /* return true if there is pending writeback records or the pending
 389  * adjust requests */
 390 static bool qsd_job_pending(struct qsd_instance *qsd, struct list_head *upd,
 391                             bool *uptodate)
 392 {
 393         bool    job_pending = false;
 394         int     qtype;
 395
 396         LASSERT(list_empty(upd));
 397         *uptodate = true;
 398
 399         spin_lock(&qsd->qsd_adjust_lock);
 400         if (!list_empty(&qsd->qsd_adjust_list)) {
 401                 struct lquota_entry *lqe;
 402                 lqe = list_entry(qsd->qsd_adjust_list.next,
 403                                      struct lquota_entry, lqe_link);
 404                 if (ktime_get_seconds() >= lqe->lqe_adjust_time)
 405                         job_pending = true;
 406         }
 407         spin_unlock(&qsd->qsd_adjust_lock);
 408
 409         write_lock(&qsd->qsd_lock);
 410         if (!list_empty(&qsd->qsd_upd_list)) {
 411                 list_splice_init(&qsd->qsd_upd_list, upd);
 412                 job_pending = true;
 413         }
 414
 415         for (qtype = USRQUOTA; qtype < LL_MAXQUOTAS; qtype++) {
 416                 struct qsd_qtype_info *qqi = qsd->qsd_type_array[qtype];
 417
 418                 /* don't bother kicking off reintegration if space accounting
 419                  * failed to be enabled */
 420                 if (qqi->qqi_acct_failed)
 421                         continue;
 422
 423                 if (!qsd_type_enabled(qsd, qtype))
 424                         continue;
 425
 426                 if ((!qqi->qqi_glb_uptodate || !qqi->qqi_slv_uptodate) &&
 427                      !qqi->qqi_reint)
 428                         /* global or slave index not up to date and reint
 429                          * thread not running */
 430                         *uptodate = false;
 431         }
 432
 433         write_unlock(&qsd->qsd_lock);
 434         return job_pending;
 435 }
 436
 437 struct qsd_upd_args {
 438         struct qsd_instance     *qua_inst;
 439         struct lu_env            qua_env;
 440         struct completion       *qua_started;
 441 };
 442
 443 #ifndef TASK_IDLE
 444 /* This identity is only safe inside kernel threads, or other places where
 445  * all signals are disabled.  So it is placed here rather than in an include
 446  * file.
 447  * TASK_IDLE was added in v4.1-rc4-43-g80ed87c8a9ca so this can be removed
 448  * when we no longer support kernels older than that.
 449  */
 450 #define TASK_IDLE TASK_INTERRUPTIBLE
 451 #endif
 452
 453 static int qsd_upd_thread(void *_args)
 454 {
 455         struct qsd_upd_args     *args = _args;
 456         struct qsd_instance     *qsd = args->qua_inst;
 457         LIST_HEAD(queue);
 458         struct qsd_upd_rec      *upd, *n;
 459         struct lu_env           *env = &args->qua_env;
 460         int                      qtype, rc = 0;
 461         bool                     uptodate;
 462         struct lquota_entry     *lqe;
 463         time64_t cur_time;
 464         ENTRY;
 465
 466         complete(args->qua_started);
 467         while (({set_current_state(TASK_IDLE);
 468                  !kthread_should_stop(); })) {
 469
 470                 if (!qsd_job_pending(qsd, &queue, &uptodate))
 471                         schedule_timeout(cfs_time_seconds(QSD_WB_INTERVAL));
 472                 __set_current_state(TASK_RUNNING);
 473
 474                 list_for_each_entry_safe(upd, n, &queue, qur_link) {
 475                         list_del_init(&upd->qur_link);
 476                         qsd_process_upd(env, upd);
 477                         qsd_upd_free(upd);
 478                 }
 479
 480                 spin_lock(&qsd->qsd_adjust_lock);
 481                 cur_time = ktime_get_seconds();
 482                 while (!list_empty(&qsd->qsd_adjust_list)) {
 483                         lqe = list_entry(qsd->qsd_adjust_list.next,
 484                                          struct lquota_entry, lqe_link);
 485                         /* deferred items are sorted by time */
 486                         if (lqe->lqe_adjust_time > cur_time)
 487                                 break;
 488
 489                         list_del_init(&lqe->lqe_link);
 490                         spin_unlock(&qsd->qsd_adjust_lock);
 491
 492                         if (!kthread_should_stop() && uptodate) {
 493                                 qsd_refresh_usage(env, lqe);
 494                                 if (lqe->lqe_adjust_time == 0)
 495                                         qsd_id_lock_cancel(env, lqe);
 496                                 else
 497                                         qsd_adjust(env, lqe);
 498                         }
 499
 500                         lqe_putref(lqe);
 501                         spin_lock(&qsd->qsd_adjust_lock);
 502                 }
 503                 spin_unlock(&qsd->qsd_adjust_lock);
 504
 505                 if (uptodate || kthread_should_stop())
 506                         continue;
 507
 508                 for (qtype = USRQUOTA; qtype < LL_MAXQUOTAS; qtype++)
 509                         qsd_start_reint_thread(qsd->qsd_type_array[qtype]);
 510         }
 511         __set_current_state(TASK_RUNNING);
 512
 513         lu_env_fini(env);
 514         OBD_FREE_PTR(args);
 515
 516         RETURN(rc);
 517 }
 518
 519 int qsd_start_upd_thread(struct qsd_instance *qsd)
 520 {
 521         struct qsd_upd_args *args;
 522         struct task_struct *task;
 523         DECLARE_COMPLETION_ONSTACK(started);
 524         int rc;
 525         ENTRY;
 526
 527         OBD_ALLOC_PTR(args);
 528         if (args == NULL)
 529                 RETURN(-ENOMEM);
 530
 531         rc = lu_env_init(&args->qua_env, LCT_DT_THREAD);
 532         if (rc) {
 533                 CERROR("%s: cannot init env: rc = %d\n", qsd->qsd_svname, rc);
 534                 goto out_free;
 535         }
 536         args->qua_inst = qsd;
 537         args->qua_started = &started;
 538
 539         task = kthread_create(qsd_upd_thread, args,
 540                               "lquota_wb_%s", qsd->qsd_svname);
 541         if (IS_ERR(task)) {
 542                 rc = PTR_ERR(task);
 543                 CERROR("fail to start quota update thread: rc = %d\n", rc);
 544                 goto out_fini;
 545         }
 546         qsd->qsd_upd_task = task;
 547         wake_up_process(task);
 548         wait_for_completion(&started);
 549
 550         RETURN(0);
 551
 552 out_fini:
 553         lu_env_fini(&args->qua_env);
 554 out_free:
 555         OBD_FREE_PTR(args);
 556         RETURN(rc);
 557 }
 558
 559 static void qsd_cleanup_deferred(struct qsd_instance *qsd)
 560 {
 561         int     qtype;
 562
 563         for (qtype = USRQUOTA; qtype < LL_MAXQUOTAS; qtype++) {
 564                 struct qsd_upd_rec      *upd, *tmp;
 565                 struct qsd_qtype_info   *qqi = qsd->qsd_type_array[qtype];
 566
 567                 if (qqi == NULL)
 568                         continue;
 569
 570                 write_lock(&qsd->qsd_lock);
 571                 list_for_each_entry_safe(upd, tmp, &qqi->qqi_deferred_glb,
 572                                          qur_link) {
 573                         CWARN("%s: Free global deferred upd: ID:%llu, "
 574                               "ver:%llu/%llu\n", qsd->qsd_svname,
 575                               upd->qur_qid.qid_uid, upd->qur_ver,
 576                               qqi->qqi_glb_ver);
 577                         list_del_init(&upd->qur_link);
 578                         qsd_upd_free(upd);
 579                 }
 580                 list_for_each_entry_safe(upd, tmp, &qqi->qqi_deferred_slv,
 581                                          qur_link) {
 582                         CWARN("%s: Free slave deferred upd: ID:%llu, "
 583                               "ver:%llu/%llu\n", qsd->qsd_svname,
 584                               upd->qur_qid.qid_uid, upd->qur_ver,
 585                               qqi->qqi_slv_ver);
 586                         list_del_init(&upd->qur_link);
 587                         qsd_upd_free(upd);
 588                 }
 589                 write_unlock(&qsd->qsd_lock);
 590         }
 591 }
 592
 593 static void qsd_cleanup_adjust(struct qsd_instance *qsd)
 594 {
 595         struct lquota_entry     *lqe;
 596
 597         spin_lock(&qsd->qsd_adjust_lock);
 598         while (!list_empty(&qsd->qsd_adjust_list)) {
 599                 lqe = list_entry(qsd->qsd_adjust_list.next,
 600                                  struct lquota_entry, lqe_link);
 601                 list_del_init(&lqe->lqe_link);
 602                 lqe_putref(lqe);
 603         }
 604         spin_unlock(&qsd->qsd_adjust_lock);
 605 }
 606
 607 void qsd_stop_upd_thread(struct qsd_instance *qsd)
 608 {
 609         struct task_struct *task;
 610
 611         write_lock(&qsd->qsd_lock);
 612         task = qsd->qsd_upd_task;
 613         qsd->qsd_upd_task = NULL;
 614         write_unlock(&qsd->qsd_lock);
 615         if (task)
 616                 kthread_stop(task);
 617
 618         qsd_cleanup_deferred(qsd);
 619         qsd_cleanup_adjust(qsd);
 620 }