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