git.oblomov.eu Git - linux-2.6/blob - 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 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 int __dlm_lockres_has_locks(struct dlm_lock_resource *res)
  83 {
  84         if (list_empty(&res->granted) &&
  85             list_empty(&res->converting) &&
  86             list_empty(&res->blocked))
  87                 return 0;
  88         return 1;
  89 }
  90
  91 /* "unused": the lockres has no locks, is not on the dirty list,
  92  * has no inflight locks (in the gap between mastery and acquiring
  93  * the first lock), and has no bits in its refmap.
  94  * truly ready to be freed. */
  95 int __dlm_lockres_unused(struct dlm_lock_resource *res)
  96 {
  97         if (!__dlm_lockres_has_locks(res) &&
  98             (list_empty(&res->dirty) && !(res->state & DLM_LOCK_RES_DIRTY))) {
  99                 /* try not to scan the bitmap unless the first two
 100                  * conditions are already true */
 101                 int bit = find_next_bit(res->refmap, O2NM_MAX_NODES, 0);
 102                 if (bit >= O2NM_MAX_NODES) {
 103                         /* since the bit for dlm->node_num is not
 104                          * set, inflight_locks better be zero */
 105                         BUG_ON(res->inflight_locks != 0);
 106                         return 1;
 107                 }
 108         }
 109         return 0;
 110 }
 111
 112
 113 /* Call whenever you may have added or deleted something from one of
 114  * the lockres queue's. This will figure out whether it belongs on the
 115  * unused list or not and does the appropriate thing. */
 116 void __dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
 117                               struct dlm_lock_resource *res)
 118 {
 119         mlog_entry("%.*s\n", res->lockname.len, res->lockname.name);
 120
 121         assert_spin_locked(&dlm->spinlock);
 122         assert_spin_locked(&res->spinlock);
 123
 124         if (__dlm_lockres_unused(res)){
 125                 if (list_empty(&res->purge)) {
 126                         mlog(0, "putting lockres %.*s:%p onto purge list\n",
 127                              res->lockname.len, res->lockname.name, res);
 128
 129                         res->last_used = jiffies;
 130                         dlm_lockres_get(res);
 131                         list_add_tail(&res->purge, &dlm->purge_list);
 132                         dlm->purge_count++;
 133                 }
 134         } else if (!list_empty(&res->purge)) {
 135                 mlog(0, "removing lockres %.*s:%p from purge list, owner=%u\n",
 136                      res->lockname.len, res->lockname.name, res, res->owner);
 137
 138                 list_del_init(&res->purge);
 139                 dlm_lockres_put(res);
 140                 dlm->purge_count--;
 141         }
 142 }
 143
 144 void dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
 145                             struct dlm_lock_resource *res)
 146 {
 147         mlog_entry("%.*s\n", res->lockname.len, res->lockname.name);
 148         spin_lock(&dlm->spinlock);
 149         spin_lock(&res->spinlock);
 150
 151         __dlm_lockres_calc_usage(dlm, res);
 152
 153         spin_unlock(&res->spinlock);
 154         spin_unlock(&dlm->spinlock);
 155 }
 156
 157 static int dlm_purge_lockres(struct dlm_ctxt *dlm,
 158                              struct dlm_lock_resource *res)
 159 {
 160         int master;
 161         int ret = 0;
 162
 163         spin_lock(&res->spinlock);
 164         if (!__dlm_lockres_unused(res)) {
 165                 spin_unlock(&res->spinlock);
 166                 mlog(0, "%s:%.*s: tried to purge but not unused\n",
 167                      dlm->name, res->lockname.len, res->lockname.name);
 168                 return -ENOTEMPTY;
 169         }
 170         master = (res->owner == dlm->node_num);
 171         if (!master)
 172                 res->state |= DLM_LOCK_RES_DROPPING_REF;
 173         spin_unlock(&res->spinlock);
 174
 175         mlog(0, "purging lockres %.*s, master = %d\n", res->lockname.len,
 176              res->lockname.name, master);
 177
 178         if (!master) {
 179                 spin_lock(&res->spinlock);
 180                 /* This ensures that clear refmap is sent after the set */
 181                 __dlm_wait_on_lockres_flags(res, DLM_LOCK_RES_SETREF_INPROG);
 182                 spin_unlock(&res->spinlock);
 183                 /* drop spinlock to do messaging, retake below */
 184                 spin_unlock(&dlm->spinlock);
 185                 /* clear our bit from the master's refmap, ignore errors */
 186                 ret = dlm_drop_lockres_ref(dlm, res);
 187                 if (ret < 0) {
 188                         mlog_errno(ret);
 189                         if (!dlm_is_host_down(ret))
 190                                 BUG();
 191                 }
 192                 mlog(0, "%s:%.*s: dlm_deref_lockres returned %d\n",
 193                      dlm->name, res->lockname.len, res->lockname.name, ret);
 194                 spin_lock(&dlm->spinlock);
 195         }
 196
 197         if (!list_empty(&res->purge)) {
 198                 mlog(0, "removing lockres %.*s:%p from purgelist, "
 199                      "master = %d\n", res->lockname.len, res->lockname.name,
 200                      res, master);
 201                 list_del_init(&res->purge);
 202                 dlm_lockres_put(res);
 203                 dlm->purge_count--;
 204         }
 205         __dlm_unhash_lockres(res);
 206
 207         /* lockres is not in the hash now.  drop the flag and wake up
 208          * any processes waiting in dlm_get_lock_resource. */
 209         if (!master) {
 210                 spin_lock(&res->spinlock);
 211                 res->state &= ~DLM_LOCK_RES_DROPPING_REF;
 212                 spin_unlock(&res->spinlock);
 213                 wake_up(&res->wq);
 214         }
 215         return 0;
 216 }
 217
 218 static void dlm_run_purge_list(struct dlm_ctxt *dlm,
 219                                int purge_now)
 220 {
 221         unsigned int run_max, unused;
 222         unsigned long purge_jiffies;
 223         struct dlm_lock_resource *lockres;
 224
 225         spin_lock(&dlm->spinlock);
 226         run_max = dlm->purge_count;
 227
 228         while(run_max && !list_empty(&dlm->purge_list)) {
 229                 run_max--;
 230
 231                 lockres = list_entry(dlm->purge_list.next,
 232                                      struct dlm_lock_resource, purge);
 233
 234                 /* Status of the lockres *might* change so double
 235                  * check. If the lockres is unused, holding the dlm
 236                  * spinlock will prevent people from getting and more
 237                  * refs on it -- there's no need to keep the lockres
 238                  * spinlock. */
 239                 spin_lock(&lockres->spinlock);
 240                 unused = __dlm_lockres_unused(lockres);
 241                 spin_unlock(&lockres->spinlock);
 242
 243                 if (!unused)
 244                         continue;
 245
 246                 purge_jiffies = lockres->last_used +
 247                         msecs_to_jiffies(DLM_PURGE_INTERVAL_MS);
 248
 249                 /* Make sure that we want to be processing this guy at
 250                  * this time. */
 251                 if (!purge_now && time_after(purge_jiffies, jiffies)) {
 252                         /* Since resources are added to the purge list
 253                          * in tail order, we can stop at the first
 254                          * unpurgable resource -- anyone added after
 255                          * him will have a greater last_used value */
 256                         break;
 257                 }
 258
 259                 mlog(0, "removing lockres %.*s:%p from purgelist\n",
 260                      lockres->lockname.len, lockres->lockname.name, lockres);
 261                 list_del_init(&lockres->purge);
 262                 dlm_lockres_put(lockres);
 263                 dlm->purge_count--;
 264
 265                 /* This may drop and reacquire the dlm spinlock if it
 266                  * has to do migration. */
 267                 mlog(0, "calling dlm_purge_lockres!\n");
 268                 dlm_lockres_get(lockres);
 269                 if (dlm_purge_lockres(dlm, lockres))
 270                         BUG();
 271                 dlm_lockres_put(lockres);
 272                 mlog(0, "DONE calling dlm_purge_lockres!\n");
 273
 274                 /* Avoid adding any scheduling latencies */
 275                 cond_resched_lock(&dlm->spinlock);
 276         }
 277
 278         spin_unlock(&dlm->spinlock);
 279 }
 280
 281 static void dlm_shuffle_lists(struct dlm_ctxt *dlm,
 282                               struct dlm_lock_resource *res)
 283 {
 284         struct dlm_lock *lock, *target;
 285         struct list_head *iter;
 286         struct list_head *head;
 287         int can_grant = 1;
 288
 289         //mlog(0, "res->lockname.len=%d\n", res->lockname.len);
 290         //mlog(0, "res->lockname.name=%p\n", res->lockname.name);
 291         //mlog(0, "shuffle res %.*s\n", res->lockname.len,
 292         //        res->lockname.name);
 293
 294         /* because this function is called with the lockres
 295          * spinlock, and because we know that it is not migrating/
 296          * recovering/in-progress, it is fine to reserve asts and
 297          * basts right before queueing them all throughout */
 298         assert_spin_locked(&res->spinlock);
 299         BUG_ON((res->state & (DLM_LOCK_RES_MIGRATING|
 300                               DLM_LOCK_RES_RECOVERING|
 301                               DLM_LOCK_RES_IN_PROGRESS)));
 302
 303 converting:
 304         if (list_empty(&res->converting))
 305                 goto blocked;
 306         mlog(0, "res %.*s has locks on a convert queue\n", res->lockname.len,
 307              res->lockname.name);
 308
 309         target = list_entry(res->converting.next, struct dlm_lock, list);
 310         if (target->ml.convert_type == LKM_IVMODE) {
 311                 mlog(ML_ERROR, "%.*s: converting a lock with no "
 312                      "convert_type!\n", res->lockname.len, res->lockname.name);
 313                 BUG();
 314         }
 315         head = &res->granted;
 316         list_for_each(iter, head) {
 317                 lock = list_entry(iter, struct dlm_lock, list);
 318                 if (lock==target)
 319                         continue;
 320                 if (!dlm_lock_compatible(lock->ml.type,
 321                                          target->ml.convert_type)) {
 322                         can_grant = 0;
 323                         /* queue the BAST if not already */
 324                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 325                                 __dlm_lockres_reserve_ast(res);
 326                                 dlm_queue_bast(dlm, lock);
 327                         }
 328                         /* update the highest_blocked if needed */
 329                         if (lock->ml.highest_blocked < target->ml.convert_type)
 330                                 lock->ml.highest_blocked =
 331                                         target->ml.convert_type;
 332                 }
 333         }
 334         head = &res->converting;
 335         list_for_each(iter, head) {
 336                 lock = list_entry(iter, struct dlm_lock, list);
 337                 if (lock==target)
 338                         continue;
 339                 if (!dlm_lock_compatible(lock->ml.type,
 340                                          target->ml.convert_type)) {
 341                         can_grant = 0;
 342                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 343                                 __dlm_lockres_reserve_ast(res);
 344                                 dlm_queue_bast(dlm, lock);
 345                         }
 346                         if (lock->ml.highest_blocked < target->ml.convert_type)
 347                                 lock->ml.highest_blocked =
 348                                         target->ml.convert_type;
 349                 }
 350         }
 351
 352         /* we can convert the lock */
 353         if (can_grant) {
 354                 spin_lock(&target->spinlock);
 355                 BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
 356
 357                 mlog(0, "calling ast for converting lock: %.*s, have: %d, "
 358                      "granting: %d, node: %u\n", res->lockname.len,
 359                      res->lockname.name, target->ml.type,
 360                      target->ml.convert_type, target->ml.node);
 361
 362                 target->ml.type = target->ml.convert_type;
 363                 target->ml.convert_type = LKM_IVMODE;
 364                 list_move_tail(&target->list, &res->granted);
 365
 366                 BUG_ON(!target->lksb);
 367                 target->lksb->status = DLM_NORMAL;
 368
 369                 spin_unlock(&target->spinlock);
 370
 371                 __dlm_lockres_reserve_ast(res);
 372                 dlm_queue_ast(dlm, target);
 373                 /* go back and check for more */
 374                 goto converting;
 375         }
 376
 377 blocked:
 378         if (list_empty(&res->blocked))
 379                 goto leave;
 380         target = list_entry(res->blocked.next, struct dlm_lock, list);
 381
 382         head = &res->granted;
 383         list_for_each(iter, head) {
 384                 lock = list_entry(iter, struct dlm_lock, list);
 385                 if (lock==target)
 386                         continue;
 387                 if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
 388                         can_grant = 0;
 389                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 390                                 __dlm_lockres_reserve_ast(res);
 391                                 dlm_queue_bast(dlm, lock);
 392                         }
 393                         if (lock->ml.highest_blocked < target->ml.type)
 394                                 lock->ml.highest_blocked = target->ml.type;
 395                 }
 396         }
 397
 398         head = &res->converting;
 399         list_for_each(iter, head) {
 400                 lock = list_entry(iter, struct dlm_lock, list);
 401                 if (lock==target)
 402                         continue;
 403                 if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
 404                         can_grant = 0;
 405                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 406                                 __dlm_lockres_reserve_ast(res);
 407                                 dlm_queue_bast(dlm, lock);
 408                         }
 409                         if (lock->ml.highest_blocked < target->ml.type)
 410                                 lock->ml.highest_blocked = target->ml.type;
 411                 }
 412         }
 413
 414         /* we can grant the blocked lock (only
 415          * possible if converting list empty) */
 416         if (can_grant) {
 417                 spin_lock(&target->spinlock);
 418                 BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
 419
 420                 mlog(0, "calling ast for blocked lock: %.*s, granting: %d, "
 421                      "node: %u\n", res->lockname.len, res->lockname.name,
 422                      target->ml.type, target->ml.node);
 423
 424                 // target->ml.type is already correct
 425                 list_move_tail(&target->list, &res->granted);
 426
 427                 BUG_ON(!target->lksb);
 428                 target->lksb->status = DLM_NORMAL;
 429
 430                 spin_unlock(&target->spinlock);
 431
 432                 __dlm_lockres_reserve_ast(res);
 433                 dlm_queue_ast(dlm, target);
 434                 /* go back and check for more */
 435                 goto converting;
 436         }
 437
 438 leave:
 439         return;
 440 }
 441
 442 /* must have NO locks when calling this with res !=NULL * */
 443 void dlm_kick_thread(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 444 {
 445         mlog_entry("dlm=%p, res=%p\n", dlm, res);
 446         if (res) {
 447                 spin_lock(&dlm->spinlock);
 448                 spin_lock(&res->spinlock);
 449                 __dlm_dirty_lockres(dlm, res);
 450                 spin_unlock(&res->spinlock);
 451                 spin_unlock(&dlm->spinlock);
 452         }
 453         wake_up(&dlm->dlm_thread_wq);
 454 }
 455
 456 void __dlm_dirty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 457 {
 458         mlog_entry("dlm=%p, res=%p\n", dlm, res);
 459
 460         assert_spin_locked(&dlm->spinlock);
 461         assert_spin_locked(&res->spinlock);
 462
 463         /* don't shuffle secondary queues */
 464         if ((res->owner == dlm->node_num)) {
 465                 if (res->state & (DLM_LOCK_RES_MIGRATING |
 466                                   DLM_LOCK_RES_BLOCK_DIRTY))
 467                     return;
 468
 469                 if (list_empty(&res->dirty)) {
 470                         /* ref for dirty_list */
 471                         dlm_lockres_get(res);
 472                         list_add_tail(&res->dirty, &dlm->dirty_list);
 473                         res->state |= DLM_LOCK_RES_DIRTY;
 474                 }
 475         }
 476 }
 477
 478
 479 /* Launch the NM thread for the mounted volume */
 480 int dlm_launch_thread(struct dlm_ctxt *dlm)
 481 {
 482         mlog(0, "starting dlm thread...\n");
 483
 484         dlm->dlm_thread_task = kthread_run(dlm_thread, dlm, "dlm_thread");
 485         if (IS_ERR(dlm->dlm_thread_task)) {
 486                 mlog_errno(PTR_ERR(dlm->dlm_thread_task));
 487                 dlm->dlm_thread_task = NULL;
 488                 return -EINVAL;
 489         }
 490
 491         return 0;
 492 }
 493
 494 void dlm_complete_thread(struct dlm_ctxt *dlm)
 495 {
 496         if (dlm->dlm_thread_task) {
 497                 mlog(ML_KTHREAD, "waiting for dlm thread to exit\n");
 498                 kthread_stop(dlm->dlm_thread_task);
 499                 dlm->dlm_thread_task = NULL;
 500         }
 501 }
 502
 503 static int dlm_dirty_list_empty(struct dlm_ctxt *dlm)
 504 {
 505         int empty;
 506
 507         spin_lock(&dlm->spinlock);
 508         empty = list_empty(&dlm->dirty_list);
 509         spin_unlock(&dlm->spinlock);
 510
 511         return empty;
 512 }
 513
 514 static void dlm_flush_asts(struct dlm_ctxt *dlm)
 515 {
 516         int ret;
 517         struct dlm_lock *lock;
 518         struct dlm_lock_resource *res;
 519         u8 hi;
 520
 521         spin_lock(&dlm->ast_lock);
 522         while (!list_empty(&dlm->pending_asts)) {
 523                 lock = list_entry(dlm->pending_asts.next,
 524                                   struct dlm_lock, ast_list);
 525                 /* get an extra ref on lock */
 526                 dlm_lock_get(lock);
 527                 res = lock->lockres;
 528                 mlog(0, "delivering an ast for this lockres\n");
 529
 530                 BUG_ON(!lock->ast_pending);
 531
 532                 /* remove from list (including ref) */
 533                 list_del_init(&lock->ast_list);
 534                 dlm_lock_put(lock);
 535                 spin_unlock(&dlm->ast_lock);
 536
 537                 if (lock->ml.node != dlm->node_num) {
 538                         ret = dlm_do_remote_ast(dlm, res, lock);
 539                         if (ret < 0)
 540                                 mlog_errno(ret);
 541                 } else
 542                         dlm_do_local_ast(dlm, res, lock);
 543
 544                 spin_lock(&dlm->ast_lock);
 545
 546                 /* possible that another ast was queued while
 547                  * we were delivering the last one */
 548                 if (!list_empty(&lock->ast_list)) {
 549                         mlog(0, "aha another ast got queued while "
 550                              "we were finishing the last one.  will "
 551                              "keep the ast_pending flag set.\n");
 552                 } else
 553                         lock->ast_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
 561         while (!list_empty(&dlm->pending_basts)) {
 562                 lock = list_entry(dlm->pending_basts.next,
 563                                   struct dlm_lock, bast_list);
 564                 /* get an extra ref on lock */
 565                 dlm_lock_get(lock);
 566                 res = lock->lockres;
 567
 568                 BUG_ON(!lock->bast_pending);
 569
 570                 /* get the highest blocked lock, and reset */
 571                 spin_lock(&lock->spinlock);
 572                 BUG_ON(lock->ml.highest_blocked <= LKM_IVMODE);
 573                 hi = lock->ml.highest_blocked;
 574                 lock->ml.highest_blocked = LKM_IVMODE;
 575                 spin_unlock(&lock->spinlock);
 576
 577                 /* remove from list (including ref) */
 578                 list_del_init(&lock->bast_list);
 579                 dlm_lock_put(lock);
 580                 spin_unlock(&dlm->ast_lock);
 581
 582                 mlog(0, "delivering a bast for this lockres "
 583                      "(blocked = %d\n", hi);
 584
 585                 if (lock->ml.node != dlm->node_num) {
 586                         ret = dlm_send_proxy_bast(dlm, res, lock, hi);
 587                         if (ret < 0)
 588                                 mlog_errno(ret);
 589                 } else
 590                         dlm_do_local_bast(dlm, res, lock, hi);
 591
 592                 spin_lock(&dlm->ast_lock);
 593
 594                 /* possible that another bast was queued while
 595                  * we were delivering the last one */
 596                 if (!list_empty(&lock->bast_list)) {
 597                         mlog(0, "aha another bast got queued while "
 598                              "we were finishing the last one.  will "
 599                              "keep the bast_pending flag set.\n");
 600                 } else
 601                         lock->bast_pending = 0;
 602
 603                 /* drop the extra ref.
 604                  * this may drop it completely. */
 605                 dlm_lock_put(lock);
 606                 dlm_lockres_release_ast(dlm, res);
 607         }
 608         wake_up(&dlm->ast_wq);
 609         spin_unlock(&dlm->ast_lock);
 610 }
 611
 612
 613 #define DLM_THREAD_TIMEOUT_MS (4 * 1000)
 614 #define DLM_THREAD_MAX_DIRTY  100
 615 #define DLM_THREAD_MAX_ASTS   10
 616
 617 static int dlm_thread(void *data)
 618 {
 619         struct dlm_lock_resource *res;
 620         struct dlm_ctxt *dlm = data;
 621         unsigned long timeout = msecs_to_jiffies(DLM_THREAD_TIMEOUT_MS);
 622
 623         mlog(0, "dlm thread running for %s...\n", dlm->name);
 624
 625         while (!kthread_should_stop()) {
 626                 int n = DLM_THREAD_MAX_DIRTY;
 627
 628                 /* dlm_shutting_down is very point-in-time, but that
 629                  * doesn't matter as we'll just loop back around if we
 630                  * get false on the leading edge of a state
 631                  * transition. */
 632                 dlm_run_purge_list(dlm, dlm_shutting_down(dlm));
 633
 634                 /* We really don't want to hold dlm->spinlock while
 635                  * calling dlm_shuffle_lists on each lockres that
 636                  * needs to have its queues adjusted and AST/BASTs
 637                  * run.  So let's pull each entry off the dirty_list
 638                  * and drop dlm->spinlock ASAP.  Once off the list,
 639                  * res->spinlock needs to be taken again to protect
 640                  * the queues while calling dlm_shuffle_lists.  */
 641                 spin_lock(&dlm->spinlock);
 642                 while (!list_empty(&dlm->dirty_list)) {
 643                         int delay = 0;
 644                         res = list_entry(dlm->dirty_list.next,
 645                                          struct dlm_lock_resource, dirty);
 646
 647                         /* peel a lockres off, remove it from the list,
 648                          * unset the dirty flag and drop the dlm lock */
 649                         BUG_ON(!res);
 650                         dlm_lockres_get(res);
 651
 652                         spin_lock(&res->spinlock);
 653                         /* We clear the DLM_LOCK_RES_DIRTY state once we shuffle lists below */
 654                         list_del_init(&res->dirty);
 655                         spin_unlock(&res->spinlock);
 656                         spin_unlock(&dlm->spinlock);
 657                         /* Drop dirty_list ref */
 658                         dlm_lockres_put(res);
 659
 660                         /* lockres can be re-dirtied/re-added to the
 661                          * dirty_list in this gap, but that is ok */
 662
 663                         spin_lock(&res->spinlock);
 664                         if (res->owner != dlm->node_num) {
 665                                 __dlm_print_one_lock_resource(res);
 666                                 mlog(ML_ERROR, "inprog:%s, mig:%s, reco:%s, dirty:%s\n",
 667                                      res->state & DLM_LOCK_RES_IN_PROGRESS ? "yes" : "no",
 668                                      res->state & DLM_LOCK_RES_MIGRATING ? "yes" : "no",
 669                                      res->state & DLM_LOCK_RES_RECOVERING ? "yes" : "no",
 670                                      res->state & DLM_LOCK_RES_DIRTY ? "yes" : "no");
 671                         }
 672                         BUG_ON(res->owner != dlm->node_num);
 673
 674                         /* it is now ok to move lockreses in these states
 675                          * to the dirty list, assuming that they will only be
 676                          * dirty for a short while. */
 677                         BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
 678                         if (res->state & (DLM_LOCK_RES_IN_PROGRESS |
 679                                           DLM_LOCK_RES_RECOVERING)) {
 680                                 /* move it to the tail and keep going */
 681                                 res->state &= ~DLM_LOCK_RES_DIRTY;
 682                                 spin_unlock(&res->spinlock);
 683                                 mlog(0, "delaying list shuffling for in-"
 684                                      "progress lockres %.*s, state=%d\n",
 685                                      res->lockname.len, res->lockname.name,
 686                                      res->state);
 687                                 delay = 1;
 688                                 goto in_progress;
 689                         }
 690
 691                         /* at this point the lockres is not migrating/
 692                          * recovering/in-progress.  we have the lockres
 693                          * spinlock and do NOT have the dlm lock.
 694                          * safe to reserve/queue asts and run the lists. */
 695
 696                         mlog(0, "calling dlm_shuffle_lists with dlm=%s, "
 697                              "res=%.*s\n", dlm->name,
 698                              res->lockname.len, res->lockname.name);
 699
 700                         /* called while holding lockres lock */
 701                         dlm_shuffle_lists(dlm, res);
 702                         res->state &= ~DLM_LOCK_RES_DIRTY;
 703                         spin_unlock(&res->spinlock);
 704
 705                         dlm_lockres_calc_usage(dlm, res);
 706
 707 in_progress:
 708
 709                         spin_lock(&dlm->spinlock);
 710                         /* if the lock was in-progress, stick
 711                          * it on the back of the list */
 712                         if (delay) {
 713                                 spin_lock(&res->spinlock);
 714                                 __dlm_dirty_lockres(dlm, res);
 715                                 spin_unlock(&res->spinlock);
 716                         }
 717                         dlm_lockres_put(res);
 718
 719                         /* unlikely, but we may need to give time to
 720                          * other tasks */
 721                         if (!--n) {
 722                                 mlog(0, "throttling dlm_thread\n");
 723                                 break;
 724                         }
 725                 }
 726
 727                 spin_unlock(&dlm->spinlock);
 728                 dlm_flush_asts(dlm);
 729
 730                 /* yield and continue right away if there is more work to do */
 731                 if (!n) {
 732                         cond_resched();
 733                         continue;
 734                 }
 735
 736                 wait_event_interruptible_timeout(dlm->dlm_thread_wq,
 737                                                  !dlm_dirty_list_empty(dlm) ||
 738                                                  kthread_should_stop(),
 739                                                  timeout);
 740         }
 741
 742         mlog(0, "quitting DLM thread\n");
 743         return 0;
 744 }