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         __set_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                 dlm_lockres_get(lockres);
 260
 261                 /* This may drop and reacquire the dlm spinlock if it
 262                  * has to do migration. */
 263                 if (dlm_purge_lockres(dlm, lockres))
 264                         BUG();
 265
 266                 dlm_lockres_put(lockres);
 267
 268                 /* Avoid adding any scheduling latencies */
 269                 cond_resched_lock(&dlm->spinlock);
 270         }
 271
 272         spin_unlock(&dlm->spinlock);
 273 }
 274
 275 static void dlm_shuffle_lists(struct dlm_ctxt *dlm,
 276                               struct dlm_lock_resource *res)
 277 {
 278         struct dlm_lock *lock, *target;
 279         struct list_head *iter;
 280         struct list_head *head;
 281         int can_grant = 1;
 282
 283         //mlog(0, "res->lockname.len=%d\n", res->lockname.len);
 284         //mlog(0, "res->lockname.name=%p\n", res->lockname.name);
 285         //mlog(0, "shuffle res %.*s\n", res->lockname.len,
 286         //        res->lockname.name);
 287
 288         /* because this function is called with the lockres
 289          * spinlock, and because we know that it is not migrating/
 290          * recovering/in-progress, it is fine to reserve asts and
 291          * basts right before queueing them all throughout */
 292         assert_spin_locked(&res->spinlock);
 293         BUG_ON((res->state & (DLM_LOCK_RES_MIGRATING|
 294                               DLM_LOCK_RES_RECOVERING|
 295                               DLM_LOCK_RES_IN_PROGRESS)));
 296
 297 converting:
 298         if (list_empty(&res->converting))
 299                 goto blocked;
 300         mlog(0, "res %.*s has locks on a convert queue\n", res->lockname.len,
 301              res->lockname.name);
 302
 303         target = list_entry(res->converting.next, struct dlm_lock, list);
 304         if (target->ml.convert_type == LKM_IVMODE) {
 305                 mlog(ML_ERROR, "%.*s: converting a lock with no "
 306                      "convert_type!\n", res->lockname.len, res->lockname.name);
 307                 BUG();
 308         }
 309         head = &res->granted;
 310         list_for_each(iter, head) {
 311                 lock = list_entry(iter, struct dlm_lock, list);
 312                 if (lock==target)
 313                         continue;
 314                 if (!dlm_lock_compatible(lock->ml.type,
 315                                          target->ml.convert_type)) {
 316                         can_grant = 0;
 317                         /* queue the BAST if not already */
 318                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 319                                 __dlm_lockres_reserve_ast(res);
 320                                 dlm_queue_bast(dlm, lock);
 321                         }
 322                         /* update the highest_blocked if needed */
 323                         if (lock->ml.highest_blocked < target->ml.convert_type)
 324                                 lock->ml.highest_blocked =
 325                                         target->ml.convert_type;
 326                 }
 327         }
 328         head = &res->converting;
 329         list_for_each(iter, head) {
 330                 lock = list_entry(iter, struct dlm_lock, list);
 331                 if (lock==target)
 332                         continue;
 333                 if (!dlm_lock_compatible(lock->ml.type,
 334                                          target->ml.convert_type)) {
 335                         can_grant = 0;
 336                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 337                                 __dlm_lockres_reserve_ast(res);
 338                                 dlm_queue_bast(dlm, lock);
 339                         }
 340                         if (lock->ml.highest_blocked < target->ml.convert_type)
 341                                 lock->ml.highest_blocked =
 342                                         target->ml.convert_type;
 343                 }
 344         }
 345
 346         /* we can convert the lock */
 347         if (can_grant) {
 348                 spin_lock(&target->spinlock);
 349                 BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
 350
 351                 mlog(0, "calling ast for converting lock: %.*s, have: %d, "
 352                      "granting: %d, node: %u\n", res->lockname.len,
 353                      res->lockname.name, target->ml.type,
 354                      target->ml.convert_type, target->ml.node);
 355
 356                 target->ml.type = target->ml.convert_type;
 357                 target->ml.convert_type = LKM_IVMODE;
 358                 list_move_tail(&target->list, &res->granted);
 359
 360                 BUG_ON(!target->lksb);
 361                 target->lksb->status = DLM_NORMAL;
 362
 363                 spin_unlock(&target->spinlock);
 364
 365                 __dlm_lockres_reserve_ast(res);
 366                 dlm_queue_ast(dlm, target);
 367                 /* go back and check for more */
 368                 goto converting;
 369         }
 370
 371 blocked:
 372         if (list_empty(&res->blocked))
 373                 goto leave;
 374         target = list_entry(res->blocked.next, struct dlm_lock, list);
 375
 376         head = &res->granted;
 377         list_for_each(iter, head) {
 378                 lock = list_entry(iter, struct dlm_lock, list);
 379                 if (lock==target)
 380                         continue;
 381                 if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
 382                         can_grant = 0;
 383                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 384                                 __dlm_lockres_reserve_ast(res);
 385                                 dlm_queue_bast(dlm, lock);
 386                         }
 387                         if (lock->ml.highest_blocked < target->ml.type)
 388                                 lock->ml.highest_blocked = target->ml.type;
 389                 }
 390         }
 391
 392         head = &res->converting;
 393         list_for_each(iter, head) {
 394                 lock = list_entry(iter, struct dlm_lock, list);
 395                 if (lock==target)
 396                         continue;
 397                 if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
 398                         can_grant = 0;
 399                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 400                                 __dlm_lockres_reserve_ast(res);
 401                                 dlm_queue_bast(dlm, lock);
 402                         }
 403                         if (lock->ml.highest_blocked < target->ml.type)
 404                                 lock->ml.highest_blocked = target->ml.type;
 405                 }
 406         }
 407
 408         /* we can grant the blocked lock (only
 409          * possible if converting list empty) */
 410         if (can_grant) {
 411                 spin_lock(&target->spinlock);
 412                 BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
 413
 414                 mlog(0, "calling ast for blocked lock: %.*s, granting: %d, "
 415                      "node: %u\n", res->lockname.len, res->lockname.name,
 416                      target->ml.type, target->ml.node);
 417
 418                 // target->ml.type is already correct
 419                 list_move_tail(&target->list, &res->granted);
 420
 421                 BUG_ON(!target->lksb);
 422                 target->lksb->status = DLM_NORMAL;
 423
 424                 spin_unlock(&target->spinlock);
 425
 426                 __dlm_lockres_reserve_ast(res);
 427                 dlm_queue_ast(dlm, target);
 428                 /* go back and check for more */
 429                 goto converting;
 430         }
 431
 432 leave:
 433         return;
 434 }
 435
 436 /* must have NO locks when calling this with res !=NULL * */
 437 void dlm_kick_thread(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 438 {
 439         mlog_entry("dlm=%p, res=%p\n", dlm, res);
 440         if (res) {
 441                 spin_lock(&dlm->spinlock);
 442                 spin_lock(&res->spinlock);
 443                 __dlm_dirty_lockres(dlm, res);
 444                 spin_unlock(&res->spinlock);
 445                 spin_unlock(&dlm->spinlock);
 446         }
 447         wake_up(&dlm->dlm_thread_wq);
 448 }
 449
 450 void __dlm_dirty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 451 {
 452         mlog_entry("dlm=%p, res=%p\n", dlm, res);
 453
 454         assert_spin_locked(&dlm->spinlock);
 455         assert_spin_locked(&res->spinlock);
 456
 457         /* don't shuffle secondary queues */
 458         if ((res->owner == dlm->node_num)) {
 459                 if (res->state & (DLM_LOCK_RES_MIGRATING |
 460                                   DLM_LOCK_RES_BLOCK_DIRTY))
 461                     return;
 462
 463                 if (list_empty(&res->dirty)) {
 464                         /* ref for dirty_list */
 465                         dlm_lockres_get(res);
 466                         list_add_tail(&res->dirty, &dlm->dirty_list);
 467                         res->state |= DLM_LOCK_RES_DIRTY;
 468                 }
 469         }
 470 }
 471
 472
 473 /* Launch the NM thread for the mounted volume */
 474 int dlm_launch_thread(struct dlm_ctxt *dlm)
 475 {
 476         mlog(0, "starting dlm thread...\n");
 477
 478         dlm->dlm_thread_task = kthread_run(dlm_thread, dlm, "dlm_thread");
 479         if (IS_ERR(dlm->dlm_thread_task)) {
 480                 mlog_errno(PTR_ERR(dlm->dlm_thread_task));
 481                 dlm->dlm_thread_task = NULL;
 482                 return -EINVAL;
 483         }
 484
 485         return 0;
 486 }
 487
 488 void dlm_complete_thread(struct dlm_ctxt *dlm)
 489 {
 490         if (dlm->dlm_thread_task) {
 491                 mlog(ML_KTHREAD, "waiting for dlm thread to exit\n");
 492                 kthread_stop(dlm->dlm_thread_task);
 493                 dlm->dlm_thread_task = NULL;
 494         }
 495 }
 496
 497 static int dlm_dirty_list_empty(struct dlm_ctxt *dlm)
 498 {
 499         int empty;
 500
 501         spin_lock(&dlm->spinlock);
 502         empty = list_empty(&dlm->dirty_list);
 503         spin_unlock(&dlm->spinlock);
 504
 505         return empty;
 506 }
 507
 508 static void dlm_flush_asts(struct dlm_ctxt *dlm)
 509 {
 510         int ret;
 511         struct dlm_lock *lock;
 512         struct dlm_lock_resource *res;
 513         u8 hi;
 514
 515         spin_lock(&dlm->ast_lock);
 516         while (!list_empty(&dlm->pending_asts)) {
 517                 lock = list_entry(dlm->pending_asts.next,
 518                                   struct dlm_lock, ast_list);
 519                 /* get an extra ref on lock */
 520                 dlm_lock_get(lock);
 521                 res = lock->lockres;
 522                 mlog(0, "delivering an ast for this lockres\n");
 523
 524                 BUG_ON(!lock->ast_pending);
 525
 526                 /* remove from list (including ref) */
 527                 list_del_init(&lock->ast_list);
 528                 dlm_lock_put(lock);
 529                 spin_unlock(&dlm->ast_lock);
 530
 531                 if (lock->ml.node != dlm->node_num) {
 532                         ret = dlm_do_remote_ast(dlm, res, lock);
 533                         if (ret < 0)
 534                                 mlog_errno(ret);
 535                 } else
 536                         dlm_do_local_ast(dlm, res, lock);
 537
 538                 spin_lock(&dlm->ast_lock);
 539
 540                 /* possible that another ast was queued while
 541                  * we were delivering the last one */
 542                 if (!list_empty(&lock->ast_list)) {
 543                         mlog(0, "aha another ast got queued while "
 544                              "we were finishing the last one.  will "
 545                              "keep the ast_pending flag set.\n");
 546                 } else
 547                         lock->ast_pending = 0;
 548
 549                 /* drop the extra ref.
 550                  * this may drop it completely. */
 551                 dlm_lock_put(lock);
 552                 dlm_lockres_release_ast(dlm, res);
 553         }
 554
 555         while (!list_empty(&dlm->pending_basts)) {
 556                 lock = list_entry(dlm->pending_basts.next,
 557                                   struct dlm_lock, bast_list);
 558                 /* get an extra ref on lock */
 559                 dlm_lock_get(lock);
 560                 res = lock->lockres;
 561
 562                 BUG_ON(!lock->bast_pending);
 563
 564                 /* get the highest blocked lock, and reset */
 565                 spin_lock(&lock->spinlock);
 566                 BUG_ON(lock->ml.highest_blocked <= LKM_IVMODE);
 567                 hi = lock->ml.highest_blocked;
 568                 lock->ml.highest_blocked = LKM_IVMODE;
 569                 spin_unlock(&lock->spinlock);
 570
 571                 /* remove from list (including ref) */
 572                 list_del_init(&lock->bast_list);
 573                 dlm_lock_put(lock);
 574                 spin_unlock(&dlm->ast_lock);
 575
 576                 mlog(0, "delivering a bast for this lockres "
 577                      "(blocked = %d\n", hi);
 578
 579                 if (lock->ml.node != dlm->node_num) {
 580                         ret = dlm_send_proxy_bast(dlm, res, lock, hi);
 581                         if (ret < 0)
 582                                 mlog_errno(ret);
 583                 } else
 584                         dlm_do_local_bast(dlm, res, lock, hi);
 585
 586                 spin_lock(&dlm->ast_lock);
 587
 588                 /* possible that another bast was queued while
 589                  * we were delivering the last one */
 590                 if (!list_empty(&lock->bast_list)) {
 591                         mlog(0, "aha another bast got queued while "
 592                              "we were finishing the last one.  will "
 593                              "keep the bast_pending flag set.\n");
 594                 } else
 595                         lock->bast_pending = 0;
 596
 597                 /* drop the extra ref.
 598                  * this may drop it completely. */
 599                 dlm_lock_put(lock);
 600                 dlm_lockres_release_ast(dlm, res);
 601         }
 602         wake_up(&dlm->ast_wq);
 603         spin_unlock(&dlm->ast_lock);
 604 }
 605
 606
 607 #define DLM_THREAD_TIMEOUT_MS (4 * 1000)
 608 #define DLM_THREAD_MAX_DIRTY  100
 609 #define DLM_THREAD_MAX_ASTS   10
 610
 611 static int dlm_thread(void *data)
 612 {
 613         struct dlm_lock_resource *res;
 614         struct dlm_ctxt *dlm = data;
 615         unsigned long timeout = msecs_to_jiffies(DLM_THREAD_TIMEOUT_MS);
 616
 617         mlog(0, "dlm thread running for %s...\n", dlm->name);
 618
 619         while (!kthread_should_stop()) {
 620                 int n = DLM_THREAD_MAX_DIRTY;
 621
 622                 /* dlm_shutting_down is very point-in-time, but that
 623                  * doesn't matter as we'll just loop back around if we
 624                  * get false on the leading edge of a state
 625                  * transition. */
 626                 dlm_run_purge_list(dlm, dlm_shutting_down(dlm));
 627
 628                 /* We really don't want to hold dlm->spinlock while
 629                  * calling dlm_shuffle_lists on each lockres that
 630                  * needs to have its queues adjusted and AST/BASTs
 631                  * run.  So let's pull each entry off the dirty_list
 632                  * and drop dlm->spinlock ASAP.  Once off the list,
 633                  * res->spinlock needs to be taken again to protect
 634                  * the queues while calling dlm_shuffle_lists.  */
 635                 spin_lock(&dlm->spinlock);
 636                 while (!list_empty(&dlm->dirty_list)) {
 637                         int delay = 0;
 638                         res = list_entry(dlm->dirty_list.next,
 639                                          struct dlm_lock_resource, dirty);
 640
 641                         /* peel a lockres off, remove it from the list,
 642                          * unset the dirty flag and drop the dlm lock */
 643                         BUG_ON(!res);
 644                         dlm_lockres_get(res);
 645
 646                         spin_lock(&res->spinlock);
 647                         /* We clear the DLM_LOCK_RES_DIRTY state once we shuffle lists below */
 648                         list_del_init(&res->dirty);
 649                         spin_unlock(&res->spinlock);
 650                         spin_unlock(&dlm->spinlock);
 651                         /* Drop dirty_list ref */
 652                         dlm_lockres_put(res);
 653
 654                         /* lockres can be re-dirtied/re-added to the
 655                          * dirty_list in this gap, but that is ok */
 656
 657                         spin_lock(&res->spinlock);
 658                         if (res->owner != dlm->node_num) {
 659                                 __dlm_print_one_lock_resource(res);
 660                                 mlog(ML_ERROR, "inprog:%s, mig:%s, reco:%s, dirty:%s\n",
 661                                      res->state & DLM_LOCK_RES_IN_PROGRESS ? "yes" : "no",
 662                                      res->state & DLM_LOCK_RES_MIGRATING ? "yes" : "no",
 663                                      res->state & DLM_LOCK_RES_RECOVERING ? "yes" : "no",
 664                                      res->state & DLM_LOCK_RES_DIRTY ? "yes" : "no");
 665                         }
 666                         BUG_ON(res->owner != dlm->node_num);
 667
 668                         /* it is now ok to move lockreses in these states
 669                          * to the dirty list, assuming that they will only be
 670                          * dirty for a short while. */
 671                         BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
 672                         if (res->state & (DLM_LOCK_RES_IN_PROGRESS |
 673                                           DLM_LOCK_RES_RECOVERING)) {
 674                                 /* move it to the tail and keep going */
 675                                 res->state &= ~DLM_LOCK_RES_DIRTY;
 676                                 spin_unlock(&res->spinlock);
 677                                 mlog(0, "delaying list shuffling for in-"
 678                                      "progress lockres %.*s, state=%d\n",
 679                                      res->lockname.len, res->lockname.name,
 680                                      res->state);
 681                                 delay = 1;
 682                                 goto in_progress;
 683                         }
 684
 685                         /* at this point the lockres is not migrating/
 686                          * recovering/in-progress.  we have the lockres
 687                          * spinlock and do NOT have the dlm lock.
 688                          * safe to reserve/queue asts and run the lists. */
 689
 690                         mlog(0, "calling dlm_shuffle_lists with dlm=%s, "
 691                              "res=%.*s\n", dlm->name,
 692                              res->lockname.len, res->lockname.name);
 693
 694                         /* called while holding lockres lock */
 695                         dlm_shuffle_lists(dlm, res);
 696                         res->state &= ~DLM_LOCK_RES_DIRTY;
 697                         spin_unlock(&res->spinlock);
 698
 699                         dlm_lockres_calc_usage(dlm, res);
 700
 701 in_progress:
 702
 703                         spin_lock(&dlm->spinlock);
 704                         /* if the lock was in-progress, stick
 705                          * it on the back of the list */
 706                         if (delay) {
 707                                 spin_lock(&res->spinlock);
 708                                 __dlm_dirty_lockres(dlm, res);
 709                                 spin_unlock(&res->spinlock);
 710                         }
 711                         dlm_lockres_put(res);
 712
 713                         /* unlikely, but we may need to give time to
 714                          * other tasks */
 715                         if (!--n) {
 716                                 mlog(0, "throttling dlm_thread\n");
 717                                 break;
 718                         }
 719                 }
 720
 721                 spin_unlock(&dlm->spinlock);
 722                 dlm_flush_asts(dlm);
 723
 724                 /* yield and continue right away if there is more work to do */
 725                 if (!n) {
 726                         cond_resched();
 727                         continue;
 728                 }
 729
 730                 wait_event_interruptible_timeout(dlm->dlm_thread_wq,
 731                                                  !dlm_dirty_list_empty(dlm) ||
 732                                                  kthread_should_stop(),
 733                                                  timeout);
 734         }
 735
 736         mlog(0, "quitting DLM thread\n");
 737         return 0;
 738 }