fs/ocfs2/dlm/dlmthread.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * dlmthread.c
   5  *
   6  * standalone DLM module
   7  *
   8  * Copyright (C) 2004 Oracle.  All rights reserved.
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public
  12  * License as published by the Free Software Foundation; either
  13  * version 2 of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public
  21  * License along with this program; if not, write to the
  22  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23  * Boston, MA 021110-1307, USA.
  24  *
  25  */
  26
  27
  28 #include <linux/module.h>
  29 #include <linux/fs.h>
  30 #include <linux/types.h>
  31 #include <linux/slab.h>
  32 #include <linux/highmem.h>
  33 #include <linux/utsname.h>
  34 #include <linux/init.h>
  35 #include <linux/sysctl.h>
  36 #include <linux/random.h>
  37 #include <linux/blkdev.h>
  38 #include <linux/socket.h>
  39 #include <linux/inet.h>
  40 #include <linux/timer.h>
  41 #include <linux/kthread.h>
  42 #include <linux/delay.h>
  43
  44
  45 #include "cluster/heartbeat.h"
  46 #include "cluster/nodemanager.h"
  47 #include "cluster/tcp.h"
  48
  49 #include "dlmapi.h"
  50 #include "dlmcommon.h"
  51 #include "dlmdomain.h"
  52
  53 #define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_THREAD)
  54 #include "cluster/masklog.h"
  55
  56 static int dlm_thread(void *data);
  57
  58 static void dlm_flush_asts(struct dlm_ctxt *dlm);
  59
  60 #define dlm_lock_is_remote(dlm, lock)     ((lock)->ml.node != (dlm)->node_num)
  61
  62 /* will exit holding res->spinlock, but may drop in function */
  63 /* waits until flags are cleared on res->state */
  64 void __dlm_wait_on_lockres_flags(struct dlm_lock_resource *res, int flags)
  65 {
  66         DECLARE_WAITQUEUE(wait, current);
  67
  68         assert_spin_locked(&res->spinlock);
  69
  70         add_wait_queue(&res->wq, &wait);
  71 repeat:
  72         set_current_state(TASK_UNINTERRUPTIBLE);
  73         if (res->state & flags) {
  74                 spin_unlock(&res->spinlock);
  75                 schedule();
  76                 spin_lock(&res->spinlock);
  77                 goto repeat;
  78         }
  79         remove_wait_queue(&res->wq, &wait);
  80         current->state = TASK_RUNNING;
  81 }
  82
  83
  84 static int __dlm_lockres_unused(struct dlm_lock_resource *res)
  85 {
  86         if (list_empty(&res->granted) &&
  87             list_empty(&res->converting) &&
  88             list_empty(&res->blocked) &&
  89             list_empty(&res->dirty))
  90                 return 1;
  91         return 0;
  92 }
  93
  94
  95 /* Call whenever you may have added or deleted something from one of
  96  * the lockres queue's. This will figure out whether it belongs on the
  97  * unused list or not and does the appropriate thing. */
  98 void __dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
  99                               struct dlm_lock_resource *res)
 100 {
 101         mlog_entry("%.*s\n", res->lockname.len, res->lockname.name);
 102
 103         assert_spin_locked(&dlm->spinlock);
 104         assert_spin_locked(&res->spinlock);
 105
 106         if (__dlm_lockres_unused(res)){
 107                 if (list_empty(&res->purge)) {
 108                         mlog(0, "putting lockres %.*s from purge list\n",
 109                              res->lockname.len, res->lockname.name);
 110
 111                         res->last_used = jiffies;
 112                         list_add_tail(&res->purge, &dlm->purge_list);
 113                         dlm->purge_count++;
 114                 }
 115         } else if (!list_empty(&res->purge)) {
 116                 mlog(0, "removing lockres %.*s from purge list\n",
 117                      res->lockname.len, res->lockname.name);
 118
 119                 list_del_init(&res->purge);
 120                 dlm->purge_count--;
 121         }
 122 }
 123
 124 void dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
 125                             struct dlm_lock_resource *res)
 126 {
 127         mlog_entry("%.*s\n", res->lockname.len, res->lockname.name);
 128         spin_lock(&dlm->spinlock);
 129         spin_lock(&res->spinlock);
 130
 131         __dlm_lockres_calc_usage(dlm, res);
 132
 133         spin_unlock(&res->spinlock);
 134         spin_unlock(&dlm->spinlock);
 135 }
 136
 137 /* TODO: Eventual API: Called with the dlm spinlock held, may drop it
 138  * to do migration, but will re-acquire before exit. */
 139 void dlm_purge_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *lockres)
 140 {
 141         int master;
 142         int ret;
 143
 144         spin_lock(&lockres->spinlock);
 145         master = lockres->owner == dlm->node_num;
 146         spin_unlock(&lockres->spinlock);
 147
 148         mlog(0, "purging lockres %.*s, master = %d\n", lockres->lockname.len,
 149              lockres->lockname.name, master);
 150
 151         /* Non master is the easy case -- no migration required, just
 152          * quit. */
 153         if (!master)
 154                 goto finish;
 155
 156         /* Wheee! Migrate lockres here! */
 157         spin_unlock(&dlm->spinlock);
 158 again:
 159
 160         ret = dlm_migrate_lockres(dlm, lockres, O2NM_MAX_NODES);
 161         if (ret == -ENOTEMPTY) {
 162                 mlog(ML_ERROR, "lockres %.*s still has local locks!\n",
 163                      lockres->lockname.len, lockres->lockname.name);
 164
 165                 BUG();
 166         } else if (ret < 0) {
 167                 mlog(ML_NOTICE, "lockres %.*s: migrate failed, retrying\n",
 168                      lockres->lockname.len, lockres->lockname.name);
 169                 msleep(100);
 170                 goto again;
 171         }
 172
 173         spin_lock(&dlm->spinlock);
 174
 175 finish:
 176         if (!list_empty(&lockres->purge)) {
 177                 list_del_init(&lockres->purge);
 178                 dlm->purge_count--;
 179         }
 180         __dlm_unhash_lockres(lockres);
 181 }
 182
 183 static void dlm_run_purge_list(struct dlm_ctxt *dlm,
 184                                int purge_now)
 185 {
 186         unsigned int run_max, unused;
 187         unsigned long purge_jiffies;
 188         struct dlm_lock_resource *lockres;
 189
 190         spin_lock(&dlm->spinlock);
 191         run_max = dlm->purge_count;
 192
 193         while(run_max && !list_empty(&dlm->purge_list)) {
 194                 run_max--;
 195
 196                 lockres = list_entry(dlm->purge_list.next,
 197                                      struct dlm_lock_resource, purge);
 198
 199                 /* Status of the lockres *might* change so double
 200                  * check. If the lockres is unused, holding the dlm
 201                  * spinlock will prevent people from getting and more
 202                  * refs on it -- there's no need to keep the lockres
 203                  * spinlock. */
 204                 spin_lock(&lockres->spinlock);
 205                 unused = __dlm_lockres_unused(lockres);
 206                 spin_unlock(&lockres->spinlock);
 207
 208                 if (!unused)
 209                         continue;
 210
 211                 purge_jiffies = lockres->last_used +
 212                         msecs_to_jiffies(DLM_PURGE_INTERVAL_MS);
 213
 214                 /* Make sure that we want to be processing this guy at
 215                  * this time. */
 216                 if (!purge_now && time_after(purge_jiffies, jiffies)) {
 217                         /* Since resources are added to the purge list
 218                          * in tail order, we can stop at the first
 219                          * unpurgable resource -- anyone added after
 220                          * him will have a greater last_used value */
 221                         break;
 222                 }
 223
 224                 list_del_init(&lockres->purge);
 225                 dlm->purge_count--;
 226
 227                 /* This may drop and reacquire the dlm spinlock if it
 228                  * has to do migration. */
 229                 mlog(0, "calling dlm_purge_lockres!\n");
 230                 dlm_purge_lockres(dlm, lockres);
 231                 mlog(0, "DONE calling dlm_purge_lockres!\n");
 232
 233                 /* Avoid adding any scheduling latencies */
 234                 cond_resched_lock(&dlm->spinlock);
 235         }
 236
 237         spin_unlock(&dlm->spinlock);
 238 }
 239
 240 static void dlm_shuffle_lists(struct dlm_ctxt *dlm,
 241                               struct dlm_lock_resource *res)
 242 {
 243         struct dlm_lock *lock, *target;
 244         struct list_head *iter;
 245         struct list_head *head;
 246         int can_grant = 1;
 247
 248         //mlog(0, "res->lockname.len=%d\n", res->lockname.len);
 249         //mlog(0, "res->lockname.name=%p\n", res->lockname.name);
 250         //mlog(0, "shuffle res %.*s\n", res->lockname.len,
 251         //        res->lockname.name);
 252
 253         /* because this function is called with the lockres
 254          * spinlock, and because we know that it is not migrating/
 255          * recovering/in-progress, it is fine to reserve asts and
 256          * basts right before queueing them all throughout */
 257         assert_spin_locked(&res->spinlock);
 258         BUG_ON((res->state & (DLM_LOCK_RES_MIGRATING|
 259                               DLM_LOCK_RES_RECOVERING|
 260                               DLM_LOCK_RES_IN_PROGRESS)));
 261
 262 converting:
 263         if (list_empty(&res->converting))
 264                 goto blocked;
 265         mlog(0, "res %.*s has locks on a convert queue\n", res->lockname.len,
 266              res->lockname.name);
 267
 268         target = list_entry(res->converting.next, struct dlm_lock, list);
 269         if (target->ml.convert_type == LKM_IVMODE) {
 270                 mlog(ML_ERROR, "%.*s: converting a lock with no "
 271                      "convert_type!\n", res->lockname.len, res->lockname.name);
 272                 BUG();
 273         }
 274         head = &res->granted;
 275         list_for_each(iter, head) {
 276                 lock = list_entry(iter, struct dlm_lock, list);
 277                 if (lock==target)
 278                         continue;
 279                 if (!dlm_lock_compatible(lock->ml.type,
 280                                          target->ml.convert_type)) {
 281                         can_grant = 0;
 282                         /* queue the BAST if not already */
 283                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 284                                 __dlm_lockres_reserve_ast(res);
 285                                 dlm_queue_bast(dlm, lock);
 286                         }
 287                         /* update the highest_blocked if needed */
 288                         if (lock->ml.highest_blocked < target->ml.convert_type)
 289                                 lock->ml.highest_blocked =
 290                                         target->ml.convert_type;
 291                 }
 292         }
 293         head = &res->converting;
 294         list_for_each(iter, head) {
 295                 lock = list_entry(iter, struct dlm_lock, list);
 296                 if (lock==target)
 297                         continue;
 298                 if (!dlm_lock_compatible(lock->ml.type,
 299                                          target->ml.convert_type)) {
 300                         can_grant = 0;
 301                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 302                                 __dlm_lockres_reserve_ast(res);
 303                                 dlm_queue_bast(dlm, lock);
 304                         }
 305                         if (lock->ml.highest_blocked < target->ml.convert_type)
 306                                 lock->ml.highest_blocked =
 307                                         target->ml.convert_type;
 308                 }
 309         }
 310
 311         /* we can convert the lock */
 312         if (can_grant) {
 313                 spin_lock(&target->spinlock);
 314                 BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
 315
 316                 mlog(0, "calling ast for converting lock: %.*s, have: %d, "
 317                      "granting: %d, node: %u\n", res->lockname.len,
 318                      res->lockname.name, target->ml.type,
 319                      target->ml.convert_type, target->ml.node);
 320
 321                 target->ml.type = target->ml.convert_type;
 322                 target->ml.convert_type = LKM_IVMODE;
 323                 list_move_tail(&target->list, &res->granted);
 324
 325                 BUG_ON(!target->lksb);
 326                 target->lksb->status = DLM_NORMAL;
 327
 328                 spin_unlock(&target->spinlock);
 329
 330                 __dlm_lockres_reserve_ast(res);
 331                 dlm_queue_ast(dlm, target);
 332                 /* go back and check for more */
 333                 goto converting;
 334         }
 335
 336 blocked:
 337         if (list_empty(&res->blocked))
 338                 goto leave;
 339         target = list_entry(res->blocked.next, struct dlm_lock, list);
 340
 341         head = &res->granted;
 342         list_for_each(iter, head) {
 343                 lock = list_entry(iter, struct dlm_lock, list);
 344                 if (lock==target)
 345                         continue;
 346                 if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
 347                         can_grant = 0;
 348                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 349                                 __dlm_lockres_reserve_ast(res);
 350                                 dlm_queue_bast(dlm, lock);
 351                         }
 352                         if (lock->ml.highest_blocked < target->ml.type)
 353                                 lock->ml.highest_blocked = target->ml.type;
 354                 }
 355         }
 356
 357         head = &res->converting;
 358         list_for_each(iter, head) {
 359                 lock = list_entry(iter, struct dlm_lock, list);
 360                 if (lock==target)
 361                         continue;
 362                 if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
 363                         can_grant = 0;
 364                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 365                                 __dlm_lockres_reserve_ast(res);
 366                                 dlm_queue_bast(dlm, lock);
 367                         }
 368                         if (lock->ml.highest_blocked < target->ml.type)
 369                                 lock->ml.highest_blocked = target->ml.type;
 370                 }
 371         }
 372
 373         /* we can grant the blocked lock (only
 374          * possible if converting list empty) */
 375         if (can_grant) {
 376                 spin_lock(&target->spinlock);
 377                 BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
 378
 379                 mlog(0, "calling ast for blocked lock: %.*s, granting: %d, "
 380                      "node: %u\n", res->lockname.len, res->lockname.name,
 381                      target->ml.type, target->ml.node);
 382
 383                 // target->ml.type is already correct
 384                 list_move_tail(&target->list, &res->granted);
 385
 386                 BUG_ON(!target->lksb);
 387                 target->lksb->status = DLM_NORMAL;
 388
 389                 spin_unlock(&target->spinlock);
 390
 391                 __dlm_lockres_reserve_ast(res);
 392                 dlm_queue_ast(dlm, target);
 393                 /* go back and check for more */
 394                 goto converting;
 395         }
 396
 397 leave:
 398         return;
 399 }
 400
 401 /* must have NO locks when calling this with res !=NULL * */
 402 void dlm_kick_thread(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 403 {
 404         mlog_entry("dlm=%p, res=%p\n", dlm, res);
 405         if (res) {
 406                 spin_lock(&dlm->spinlock);
 407                 spin_lock(&res->spinlock);
 408                 __dlm_dirty_lockres(dlm, res);
 409                 spin_unlock(&res->spinlock);
 410                 spin_unlock(&dlm->spinlock);
 411         }
 412         wake_up(&dlm->dlm_thread_wq);
 413 }
 414
 415 void __dlm_dirty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 416 {
 417         mlog_entry("dlm=%p, res=%p\n", dlm, res);
 418
 419         assert_spin_locked(&dlm->spinlock);
 420         assert_spin_locked(&res->spinlock);
 421
 422         /* don't shuffle secondary queues */
 423         if ((res->owner == dlm->node_num) &&
 424             !(res->state & DLM_LOCK_RES_DIRTY)) {
 425                 list_add_tail(&res->dirty, &dlm->dirty_list);
 426                 res->state |= DLM_LOCK_RES_DIRTY;
 427         }
 428 }
 429
 430
 431 /* Launch the NM thread for the mounted volume */
 432 int dlm_launch_thread(struct dlm_ctxt *dlm)
 433 {
 434         mlog(0, "starting dlm thread...\n");
 435
 436         dlm->dlm_thread_task = kthread_run(dlm_thread, dlm, "dlm_thread");
 437         if (IS_ERR(dlm->dlm_thread_task)) {
 438                 mlog_errno(PTR_ERR(dlm->dlm_thread_task));
 439                 dlm->dlm_thread_task = NULL;
 440                 return -EINVAL;
 441         }
 442
 443         return 0;
 444 }
 445
 446 void dlm_complete_thread(struct dlm_ctxt *dlm)
 447 {
 448         if (dlm->dlm_thread_task) {
 449                 mlog(ML_KTHREAD, "waiting for dlm thread to exit\n");
 450                 kthread_stop(dlm->dlm_thread_task);
 451                 dlm->dlm_thread_task = NULL;
 452         }
 453 }
 454
 455 static int dlm_dirty_list_empty(struct dlm_ctxt *dlm)
 456 {
 457         int empty;
 458
 459         spin_lock(&dlm->spinlock);
 460         empty = list_empty(&dlm->dirty_list);
 461         spin_unlock(&dlm->spinlock);
 462
 463         return empty;
 464 }
 465
 466 static void dlm_flush_asts(struct dlm_ctxt *dlm)
 467 {
 468         int ret;
 469         struct dlm_lock *lock;
 470         struct dlm_lock_resource *res;
 471         u8 hi;
 472
 473         spin_lock(&dlm->ast_lock);
 474         while (!list_empty(&dlm->pending_asts)) {
 475                 lock = list_entry(dlm->pending_asts.next,
 476                                   struct dlm_lock, ast_list);
 477                 /* get an extra ref on lock */
 478                 dlm_lock_get(lock);
 479                 res = lock->lockres;
 480                 mlog(0, "delivering an ast for this lockres\n");
 481
 482                 BUG_ON(!lock->ast_pending);
 483
 484                 /* remove from list (including ref) */
 485                 list_del_init(&lock->ast_list);
 486                 dlm_lock_put(lock);
 487                 spin_unlock(&dlm->ast_lock);
 488
 489                 if (lock->ml.node != dlm->node_num) {
 490                         ret = dlm_do_remote_ast(dlm, res, lock);
 491                         if (ret < 0)
 492                                 mlog_errno(ret);
 493                 } else
 494                         dlm_do_local_ast(dlm, res, lock);
 495
 496                 spin_lock(&dlm->ast_lock);
 497
 498                 /* possible that another ast was queued while
 499                  * we were delivering the last one */
 500                 if (!list_empty(&lock->ast_list)) {
 501                         mlog(0, "aha another ast got queued while "
 502                              "we were finishing the last one.  will "
 503                              "keep the ast_pending flag set.\n");
 504                 } else
 505                         lock->ast_pending = 0;
 506
 507                 /* drop the extra ref.
 508                  * this may drop it completely. */
 509                 dlm_lock_put(lock);
 510                 dlm_lockres_release_ast(dlm, res);
 511         }
 512
 513         while (!list_empty(&dlm->pending_basts)) {
 514                 lock = list_entry(dlm->pending_basts.next,
 515                                   struct dlm_lock, bast_list);
 516                 /* get an extra ref on lock */
 517                 dlm_lock_get(lock);
 518                 res = lock->lockres;
 519
 520                 BUG_ON(!lock->bast_pending);
 521
 522                 /* get the highest blocked lock, and reset */
 523                 spin_lock(&lock->spinlock);
 524                 BUG_ON(lock->ml.highest_blocked <= LKM_IVMODE);
 525                 hi = lock->ml.highest_blocked;
 526                 lock->ml.highest_blocked = LKM_IVMODE;
 527                 spin_unlock(&lock->spinlock);
 528
 529                 /* remove from list (including ref) */
 530                 list_del_init(&lock->bast_list);
 531                 dlm_lock_put(lock);
 532                 spin_unlock(&dlm->ast_lock);
 533
 534                 mlog(0, "delivering a bast for this lockres "
 535                      "(blocked = %d\n", hi);
 536
 537                 if (lock->ml.node != dlm->node_num) {
 538                         ret = dlm_send_proxy_bast(dlm, res, lock, hi);
 539                         if (ret < 0)
 540                                 mlog_errno(ret);
 541                 } else
 542                         dlm_do_local_bast(dlm, res, lock, hi);
 543
 544                 spin_lock(&dlm->ast_lock);
 545
 546                 /* possible that another bast was queued while
 547                  * we were delivering the last one */
 548                 if (!list_empty(&lock->bast_list)) {
 549                         mlog(0, "aha another bast got queued while "
 550                              "we were finishing the last one.  will "
 551                              "keep the bast_pending flag set.\n");
 552                 } else
 553                         lock->bast_pending = 0;
 554
 555                 /* drop the extra ref.
 556                  * this may drop it completely. */
 557                 dlm_lock_put(lock);
 558                 dlm_lockres_release_ast(dlm, res);
 559         }
 560         wake_up(&dlm->ast_wq);
 561         spin_unlock(&dlm->ast_lock);
 562 }
 563
 564
 565 #define DLM_THREAD_TIMEOUT_MS (4 * 1000)
 566 #define DLM_THREAD_MAX_DIRTY  100
 567 #define DLM_THREAD_MAX_ASTS   10
 568
 569 static int dlm_thread(void *data)
 570 {
 571         struct dlm_lock_resource *res;
 572         struct dlm_ctxt *dlm = data;
 573         unsigned long timeout = msecs_to_jiffies(DLM_THREAD_TIMEOUT_MS);
 574
 575         mlog(0, "dlm thread running for %s...\n", dlm->name);
 576
 577         while (!kthread_should_stop()) {
 578                 int n = DLM_THREAD_MAX_DIRTY;
 579
 580                 /* dlm_shutting_down is very point-in-time, but that
 581                  * doesn't matter as we'll just loop back around if we
 582                  * get false on the leading edge of a state
 583                  * transition. */
 584                 dlm_run_purge_list(dlm, dlm_shutting_down(dlm));
 585
 586                 /* We really don't want to hold dlm->spinlock while
 587                  * calling dlm_shuffle_lists on each lockres that
 588                  * needs to have its queues adjusted and AST/BASTs
 589                  * run.  So let's pull each entry off the dirty_list
 590                  * and drop dlm->spinlock ASAP.  Once off the list,
 591                  * res->spinlock needs to be taken again to protect
 592                  * the queues while calling dlm_shuffle_lists.  */
 593                 spin_lock(&dlm->spinlock);
 594                 while (!list_empty(&dlm->dirty_list)) {
 595                         int delay = 0;
 596                         res = list_entry(dlm->dirty_list.next,
 597                                          struct dlm_lock_resource, dirty);
 598
 599                         /* peel a lockres off, remove it from the list,
 600                          * unset the dirty flag and drop the dlm lock */
 601                         BUG_ON(!res);
 602                         dlm_lockres_get(res);
 603
 604                         spin_lock(&res->spinlock);
 605                         res->state &= ~DLM_LOCK_RES_DIRTY;
 606                         list_del_init(&res->dirty);
 607                         spin_unlock(&res->spinlock);
 608                         spin_unlock(&dlm->spinlock);
 609
 610                         /* lockres can be re-dirtied/re-added to the
 611                          * dirty_list in this gap, but that is ok */
 612
 613                         spin_lock(&res->spinlock);
 614                         if (res->owner != dlm->node_num) {
 615                                 __dlm_print_one_lock_resource(res);
 616                                 mlog(ML_ERROR, "inprog:%s, mig:%s, reco:%s, dirty:%s\n",
 617                                      res->state & DLM_LOCK_RES_IN_PROGRESS ? "yes" : "no",
 618                                      res->state & DLM_LOCK_RES_MIGRATING ? "yes" : "no",
 619                                      res->state & DLM_LOCK_RES_RECOVERING ? "yes" : "no",
 620                                      res->state & DLM_LOCK_RES_DIRTY ? "yes" : "no");
 621                         }
 622                         BUG_ON(res->owner != dlm->node_num);
 623
 624                         /* it is now ok to move lockreses in these states
 625                          * to the dirty list, assuming that they will only be
 626                          * dirty for a short while. */
 627                         if (res->state & (DLM_LOCK_RES_IN_PROGRESS |
 628                                           DLM_LOCK_RES_MIGRATING |
 629                                           DLM_LOCK_RES_RECOVERING)) {
 630                                 /* move it to the tail and keep going */
 631                                 spin_unlock(&res->spinlock);
 632                                 mlog(0, "delaying list shuffling for in-"
 633                                      "progress lockres %.*s, state=%d\n",
 634                                      res->lockname.len, res->lockname.name,
 635                                      res->state);
 636                                 delay = 1;
 637                                 goto in_progress;
 638                         }
 639
 640                         /* at this point the lockres is not migrating/
 641                          * recovering/in-progress.  we have the lockres
 642                          * spinlock and do NOT have the dlm lock.
 643                          * safe to reserve/queue asts and run the lists. */
 644
 645                         mlog(0, "calling dlm_shuffle_lists with dlm=%s, "
 646                              "res=%.*s\n", dlm->name,
 647                              res->lockname.len, res->lockname.name);
 648
 649                         /* called while holding lockres lock */
 650                         dlm_shuffle_lists(dlm, res);
 651                         spin_unlock(&res->spinlock);
 652
 653                         dlm_lockres_calc_usage(dlm, res);
 654
 655 in_progress:
 656
 657                         spin_lock(&dlm->spinlock);
 658                         /* if the lock was in-progress, stick
 659                          * it on the back of the list */
 660                         if (delay) {
 661                                 spin_lock(&res->spinlock);
 662                                 list_add_tail(&res->dirty, &dlm->dirty_list);
 663                                 res->state |= DLM_LOCK_RES_DIRTY;
 664                                 spin_unlock(&res->spinlock);
 665                         }
 666                         dlm_lockres_put(res);
 667
 668                         /* unlikely, but we may need to give time to
 669                          * other tasks */
 670                         if (!--n) {
 671                                 mlog(0, "throttling dlm_thread\n");
 672                                 break;
 673                         }
 674                 }
 675
 676                 spin_unlock(&dlm->spinlock);
 677                 dlm_flush_asts(dlm);
 678
 679                 /* yield and continue right away if there is more work to do */
 680                 if (!n) {
 681                         yield();
 682                         continue;
 683                 }
 684
 685                 wait_event_interruptible_timeout(dlm->dlm_thread_wq,
 686                                                  !dlm_dirty_list_empty(dlm) ||
 687                                                  kthread_should_stop(),
 688                                                  timeout);
 689         }
 690
 691         mlog(0, "quitting DLM thread\n");
 692         return 0;
 693 }