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   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                 /* drop spinlock...  retake below */
 180                 spin_unlock(&dlm->spinlock);
 181
 182                 spin_lock(&res->spinlock);
 183                 /* This ensures that clear refmap is sent after the set */
 184                 __dlm_wait_on_lockres_flags(res, (DLM_LOCK_RES_SETREF_INPROG |
 185                                                   DLM_LOCK_RES_MIGRATING));
 186                 spin_unlock(&res->spinlock);
 187
 188                 /* clear our bit from the master's refmap, ignore errors */
 189                 ret = dlm_drop_lockres_ref(dlm, res);
 190                 if (ret < 0) {
 191                         mlog_errno(ret);
 192                         if (!dlm_is_host_down(ret))
 193                                 BUG();
 194                 }
 195                 mlog(0, "%s:%.*s: dlm_deref_lockres returned %d\n",
 196                      dlm->name, res->lockname.len, res->lockname.name, ret);
 197                 spin_lock(&dlm->spinlock);
 198         }
 199
 200         if (!list_empty(&res->purge)) {
 201                 mlog(0, "removing lockres %.*s:%p from purgelist, "
 202                      "master = %d\n", res->lockname.len, res->lockname.name,
 203                      res, master);
 204                 list_del_init(&res->purge);
 205                 dlm_lockres_put(res);
 206                 dlm->purge_count--;
 207         }
 208         __dlm_unhash_lockres(res);
 209
 210         /* lockres is not in the hash now.  drop the flag and wake up
 211          * any processes waiting in dlm_get_lock_resource. */
 212         if (!master) {
 213                 spin_lock(&res->spinlock);
 214                 res->state &= ~DLM_LOCK_RES_DROPPING_REF;
 215                 spin_unlock(&res->spinlock);
 216                 wake_up(&res->wq);
 217         }
 218         return 0;
 219 }
 220
 221 static void dlm_run_purge_list(struct dlm_ctxt *dlm,
 222                                int purge_now)
 223 {
 224         unsigned int run_max, unused;
 225         unsigned long purge_jiffies;
 226         struct dlm_lock_resource *lockres;
 227
 228         spin_lock(&dlm->spinlock);
 229         run_max = dlm->purge_count;
 230
 231         while(run_max && !list_empty(&dlm->purge_list)) {
 232                 run_max--;
 233
 234                 lockres = list_entry(dlm->purge_list.next,
 235                                      struct dlm_lock_resource, purge);
 236
 237                 /* Status of the lockres *might* change so double
 238                  * check. If the lockres is unused, holding the dlm
 239                  * spinlock will prevent people from getting and more
 240                  * refs on it -- there's no need to keep the lockres
 241                  * spinlock. */
 242                 spin_lock(&lockres->spinlock);
 243                 unused = __dlm_lockres_unused(lockres);
 244                 spin_unlock(&lockres->spinlock);
 245
 246                 if (!unused)
 247                         continue;
 248
 249                 purge_jiffies = lockres->last_used +
 250                         msecs_to_jiffies(DLM_PURGE_INTERVAL_MS);
 251
 252                 /* Make sure that we want to be processing this guy at
 253                  * this time. */
 254                 if (!purge_now && time_after(purge_jiffies, jiffies)) {
 255                         /* Since resources are added to the purge list
 256                          * in tail order, we can stop at the first
 257                          * unpurgable resource -- anyone added after
 258                          * him will have a greater last_used value */
 259                         break;
 260                 }
 261
 262                 dlm_lockres_get(lockres);
 263
 264                 /* This may drop and reacquire the dlm spinlock if it
 265                  * has to do migration. */
 266                 if (dlm_purge_lockres(dlm, lockres))
 267                         BUG();
 268
 269                 dlm_lockres_put(lockres);
 270
 271                 /* Avoid adding any scheduling latencies */
 272                 cond_resched_lock(&dlm->spinlock);
 273         }
 274
 275         spin_unlock(&dlm->spinlock);
 276 }
 277
 278 static void dlm_shuffle_lists(struct dlm_ctxt *dlm,
 279                               struct dlm_lock_resource *res)
 280 {
 281         struct dlm_lock *lock, *target;
 282         struct list_head *iter;
 283         struct list_head *head;
 284         int can_grant = 1;
 285
 286         //mlog(0, "res->lockname.len=%d\n", res->lockname.len);
 287         //mlog(0, "res->lockname.name=%p\n", res->lockname.name);
 288         //mlog(0, "shuffle res %.*s\n", res->lockname.len,
 289         //        res->lockname.name);
 290
 291         /* because this function is called with the lockres
 292          * spinlock, and because we know that it is not migrating/
 293          * recovering/in-progress, it is fine to reserve asts and
 294          * basts right before queueing them all throughout */
 295         assert_spin_locked(&res->spinlock);
 296         BUG_ON((res->state & (DLM_LOCK_RES_MIGRATING|
 297                               DLM_LOCK_RES_RECOVERING|
 298                               DLM_LOCK_RES_IN_PROGRESS)));
 299
 300 converting:
 301         if (list_empty(&res->converting))
 302                 goto blocked;
 303         mlog(0, "res %.*s has locks on a convert queue\n", res->lockname.len,
 304              res->lockname.name);
 305
 306         target = list_entry(res->converting.next, struct dlm_lock, list);
 307         if (target->ml.convert_type == LKM_IVMODE) {
 308                 mlog(ML_ERROR, "%.*s: converting a lock with no "
 309                      "convert_type!\n", res->lockname.len, res->lockname.name);
 310                 BUG();
 311         }
 312         head = &res->granted;
 313         list_for_each(iter, head) {
 314                 lock = list_entry(iter, struct dlm_lock, list);
 315                 if (lock==target)
 316                         continue;
 317                 if (!dlm_lock_compatible(lock->ml.type,
 318                                          target->ml.convert_type)) {
 319                         can_grant = 0;
 320                         /* queue the BAST if not already */
 321                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 322                                 __dlm_lockres_reserve_ast(res);
 323                                 dlm_queue_bast(dlm, lock);
 324                         }
 325                         /* update the highest_blocked if needed */
 326                         if (lock->ml.highest_blocked < target->ml.convert_type)
 327                                 lock->ml.highest_blocked =
 328                                         target->ml.convert_type;
 329                 }
 330         }
 331         head = &res->converting;
 332         list_for_each(iter, head) {
 333                 lock = list_entry(iter, struct dlm_lock, list);
 334                 if (lock==target)
 335                         continue;
 336                 if (!dlm_lock_compatible(lock->ml.type,
 337                                          target->ml.convert_type)) {
 338                         can_grant = 0;
 339                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 340                                 __dlm_lockres_reserve_ast(res);
 341                                 dlm_queue_bast(dlm, lock);
 342                         }
 343                         if (lock->ml.highest_blocked < target->ml.convert_type)
 344                                 lock->ml.highest_blocked =
 345                                         target->ml.convert_type;
 346                 }
 347         }
 348
 349         /* we can convert the lock */
 350         if (can_grant) {
 351                 spin_lock(&target->spinlock);
 352                 BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
 353
 354                 mlog(0, "calling ast for converting lock: %.*s, have: %d, "
 355                      "granting: %d, node: %u\n", res->lockname.len,
 356                      res->lockname.name, target->ml.type,
 357                      target->ml.convert_type, target->ml.node);
 358
 359                 target->ml.type = target->ml.convert_type;
 360                 target->ml.convert_type = LKM_IVMODE;
 361                 list_move_tail(&target->list, &res->granted);
 362
 363                 BUG_ON(!target->lksb);
 364                 target->lksb->status = DLM_NORMAL;
 365
 366                 spin_unlock(&target->spinlock);
 367
 368                 __dlm_lockres_reserve_ast(res);
 369                 dlm_queue_ast(dlm, target);
 370                 /* go back and check for more */
 371                 goto converting;
 372         }
 373
 374 blocked:
 375         if (list_empty(&res->blocked))
 376                 goto leave;
 377         target = list_entry(res->blocked.next, struct dlm_lock, list);
 378
 379         head = &res->granted;
 380         list_for_each(iter, head) {
 381                 lock = list_entry(iter, struct dlm_lock, list);
 382                 if (lock==target)
 383                         continue;
 384                 if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
 385                         can_grant = 0;
 386                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 387                                 __dlm_lockres_reserve_ast(res);
 388                                 dlm_queue_bast(dlm, lock);
 389                         }
 390                         if (lock->ml.highest_blocked < target->ml.type)
 391                                 lock->ml.highest_blocked = target->ml.type;
 392                 }
 393         }
 394
 395         head = &res->converting;
 396         list_for_each(iter, head) {
 397                 lock = list_entry(iter, struct dlm_lock, list);
 398                 if (lock==target)
 399                         continue;
 400                 if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
 401                         can_grant = 0;
 402                         if (lock->ml.highest_blocked == LKM_IVMODE) {
 403                                 __dlm_lockres_reserve_ast(res);
 404                                 dlm_queue_bast(dlm, lock);
 405                         }
 406                         if (lock->ml.highest_blocked < target->ml.type)
 407                                 lock->ml.highest_blocked = target->ml.type;
 408                 }
 409         }
 410
 411         /* we can grant the blocked lock (only
 412          * possible if converting list empty) */
 413         if (can_grant) {
 414                 spin_lock(&target->spinlock);
 415                 BUG_ON(target->ml.highest_blocked != LKM_IVMODE);
 416
 417                 mlog(0, "calling ast for blocked lock: %.*s, granting: %d, "
 418                      "node: %u\n", res->lockname.len, res->lockname.name,
 419                      target->ml.type, target->ml.node);
 420
 421                 // target->ml.type is already correct
 422                 list_move_tail(&target->list, &res->granted);
 423
 424                 BUG_ON(!target->lksb);
 425                 target->lksb->status = DLM_NORMAL;
 426
 427                 spin_unlock(&target->spinlock);
 428
 429                 __dlm_lockres_reserve_ast(res);
 430                 dlm_queue_ast(dlm, target);
 431                 /* go back and check for more */
 432                 goto converting;
 433         }
 434
 435 leave:
 436         return;
 437 }
 438
 439 /* must have NO locks when calling this with res !=NULL * */
 440 void dlm_kick_thread(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 441 {
 442         mlog_entry("dlm=%p, res=%p\n", dlm, res);
 443         if (res) {
 444                 spin_lock(&dlm->spinlock);
 445                 spin_lock(&res->spinlock);
 446                 __dlm_dirty_lockres(dlm, res);
 447                 spin_unlock(&res->spinlock);
 448                 spin_unlock(&dlm->spinlock);
 449         }
 450         wake_up(&dlm->dlm_thread_wq);
 451 }
 452
 453 void __dlm_dirty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
 454 {
 455         mlog_entry("dlm=%p, res=%p\n", dlm, res);
 456
 457         assert_spin_locked(&dlm->spinlock);
 458         assert_spin_locked(&res->spinlock);
 459
 460         /* don't shuffle secondary queues */
 461         if ((res->owner == dlm->node_num)) {
 462                 if (res->state & (DLM_LOCK_RES_MIGRATING |
 463                                   DLM_LOCK_RES_BLOCK_DIRTY))
 464                     return;
 465
 466                 if (list_empty(&res->dirty)) {
 467                         /* ref for dirty_list */
 468                         dlm_lockres_get(res);
 469                         list_add_tail(&res->dirty, &dlm->dirty_list);
 470                         res->state |= DLM_LOCK_RES_DIRTY;
 471                 }
 472         }
 473 }
 474
 475
 476 /* Launch the NM thread for the mounted volume */
 477 int dlm_launch_thread(struct dlm_ctxt *dlm)
 478 {
 479         mlog(0, "starting dlm thread...\n");
 480
 481         dlm->dlm_thread_task = kthread_run(dlm_thread, dlm, "dlm_thread");
 482         if (IS_ERR(dlm->dlm_thread_task)) {
 483                 mlog_errno(PTR_ERR(dlm->dlm_thread_task));
 484                 dlm->dlm_thread_task = NULL;
 485                 return -EINVAL;
 486         }
 487
 488         return 0;
 489 }
 490
 491 void dlm_complete_thread(struct dlm_ctxt *dlm)
 492 {
 493         if (dlm->dlm_thread_task) {
 494                 mlog(ML_KTHREAD, "waiting for dlm thread to exit\n");
 495                 kthread_stop(dlm->dlm_thread_task);
 496                 dlm->dlm_thread_task = NULL;
 497         }
 498 }
 499
 500 static int dlm_dirty_list_empty(struct dlm_ctxt *dlm)
 501 {
 502         int empty;
 503
 504         spin_lock(&dlm->spinlock);
 505         empty = list_empty(&dlm->dirty_list);
 506         spin_unlock(&dlm->spinlock);
 507
 508         return empty;
 509 }
 510
 511 static void dlm_flush_asts(struct dlm_ctxt *dlm)
 512 {
 513         int ret;
 514         struct dlm_lock *lock;
 515         struct dlm_lock_resource *res;
 516         u8 hi;
 517
 518         spin_lock(&dlm->ast_lock);
 519         while (!list_empty(&dlm->pending_asts)) {
 520                 lock = list_entry(dlm->pending_asts.next,
 521                                   struct dlm_lock, ast_list);
 522                 /* get an extra ref on lock */
 523                 dlm_lock_get(lock);
 524                 res = lock->lockres;
 525                 mlog(0, "delivering an ast for this lockres\n");
 526
 527                 BUG_ON(!lock->ast_pending);
 528
 529                 /* remove from list (including ref) */
 530                 list_del_init(&lock->ast_list);
 531                 dlm_lock_put(lock);
 532                 spin_unlock(&dlm->ast_lock);
 533
 534                 if (lock->ml.node != dlm->node_num) {
 535                         ret = dlm_do_remote_ast(dlm, res, lock);
 536                         if (ret < 0)
 537                                 mlog_errno(ret);
 538                 } else
 539                         dlm_do_local_ast(dlm, res, lock);
 540
 541                 spin_lock(&dlm->ast_lock);
 542
 543                 /* possible that another ast was queued while
 544                  * we were delivering the last one */
 545                 if (!list_empty(&lock->ast_list)) {
 546                         mlog(0, "aha another ast got queued while "
 547                              "we were finishing the last one.  will "
 548                              "keep the ast_pending flag set.\n");
 549                 } else
 550                         lock->ast_pending = 0;
 551
 552                 /* drop the extra ref.
 553                  * this may drop it completely. */
 554                 dlm_lock_put(lock);
 555                 dlm_lockres_release_ast(dlm, res);
 556         }
 557
 558         while (!list_empty(&dlm->pending_basts)) {
 559                 lock = list_entry(dlm->pending_basts.next,
 560                                   struct dlm_lock, bast_list);
 561                 /* get an extra ref on lock */
 562                 dlm_lock_get(lock);
 563                 res = lock->lockres;
 564
 565                 BUG_ON(!lock->bast_pending);
 566
 567                 /* get the highest blocked lock, and reset */
 568                 spin_lock(&lock->spinlock);
 569                 BUG_ON(lock->ml.highest_blocked <= LKM_IVMODE);
 570                 hi = lock->ml.highest_blocked;
 571                 lock->ml.highest_blocked = LKM_IVMODE;
 572                 spin_unlock(&lock->spinlock);
 573
 574                 /* remove from list (including ref) */
 575                 list_del_init(&lock->bast_list);
 576                 dlm_lock_put(lock);
 577                 spin_unlock(&dlm->ast_lock);
 578
 579                 mlog(0, "delivering a bast for this lockres "
 580                      "(blocked = %d\n", hi);
 581
 582                 if (lock->ml.node != dlm->node_num) {
 583                         ret = dlm_send_proxy_bast(dlm, res, lock, hi);
 584                         if (ret < 0)
 585                                 mlog_errno(ret);
 586                 } else
 587                         dlm_do_local_bast(dlm, res, lock, hi);
 588
 589                 spin_lock(&dlm->ast_lock);
 590
 591                 /* possible that another bast was queued while
 592                  * we were delivering the last one */
 593                 if (!list_empty(&lock->bast_list)) {
 594                         mlog(0, "aha another bast got queued while "
 595                              "we were finishing the last one.  will "
 596                              "keep the bast_pending flag set.\n");
 597                 } else
 598                         lock->bast_pending = 0;
 599
 600                 /* drop the extra ref.
 601                  * this may drop it completely. */
 602                 dlm_lock_put(lock);
 603                 dlm_lockres_release_ast(dlm, res);
 604         }
 605         wake_up(&dlm->ast_wq);
 606         spin_unlock(&dlm->ast_lock);
 607 }
 608
 609
 610 #define DLM_THREAD_TIMEOUT_MS (4 * 1000)
 611 #define DLM_THREAD_MAX_DIRTY  100
 612 #define DLM_THREAD_MAX_ASTS   10
 613
 614 static int dlm_thread(void *data)
 615 {
 616         struct dlm_lock_resource *res;
 617         struct dlm_ctxt *dlm = data;
 618         unsigned long timeout = msecs_to_jiffies(DLM_THREAD_TIMEOUT_MS);
 619
 620         mlog(0, "dlm thread running for %s...\n", dlm->name);
 621
 622         while (!kthread_should_stop()) {
 623                 int n = DLM_THREAD_MAX_DIRTY;
 624
 625                 /* dlm_shutting_down is very point-in-time, but that
 626                  * doesn't matter as we'll just loop back around if we
 627                  * get false on the leading edge of a state
 628                  * transition. */
 629                 dlm_run_purge_list(dlm, dlm_shutting_down(dlm));
 630
 631                 /* We really don't want to hold dlm->spinlock while
 632                  * calling dlm_shuffle_lists on each lockres that
 633                  * needs to have its queues adjusted and AST/BASTs
 634                  * run.  So let's pull each entry off the dirty_list
 635                  * and drop dlm->spinlock ASAP.  Once off the list,
 636                  * res->spinlock needs to be taken again to protect
 637                  * the queues while calling dlm_shuffle_lists.  */
 638                 spin_lock(&dlm->spinlock);
 639                 while (!list_empty(&dlm->dirty_list)) {
 640                         int delay = 0;
 641                         res = list_entry(dlm->dirty_list.next,
 642                                          struct dlm_lock_resource, dirty);
 643
 644                         /* peel a lockres off, remove it from the list,
 645                          * unset the dirty flag and drop the dlm lock */
 646                         BUG_ON(!res);
 647                         dlm_lockres_get(res);
 648
 649                         spin_lock(&res->spinlock);
 650                         /* We clear the DLM_LOCK_RES_DIRTY state once we shuffle lists below */
 651                         list_del_init(&res->dirty);
 652                         spin_unlock(&res->spinlock);
 653                         spin_unlock(&dlm->spinlock);
 654                         /* Drop dirty_list ref */
 655                         dlm_lockres_put(res);
 656
 657                         /* lockres can be re-dirtied/re-added to the
 658                          * dirty_list in this gap, but that is ok */
 659
 660                         spin_lock(&res->spinlock);
 661                         if (res->owner != dlm->node_num) {
 662                                 __dlm_print_one_lock_resource(res);
 663                                 mlog(ML_ERROR, "inprog:%s, mig:%s, reco:%s, dirty:%s\n",
 664                                      res->state & DLM_LOCK_RES_IN_PROGRESS ? "yes" : "no",
 665                                      res->state & DLM_LOCK_RES_MIGRATING ? "yes" : "no",
 666                                      res->state & DLM_LOCK_RES_RECOVERING ? "yes" : "no",
 667                                      res->state & DLM_LOCK_RES_DIRTY ? "yes" : "no");
 668                         }
 669                         BUG_ON(res->owner != dlm->node_num);
 670
 671                         /* it is now ok to move lockreses in these states
 672                          * to the dirty list, assuming that they will only be
 673                          * dirty for a short while. */
 674                         BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
 675                         if (res->state & (DLM_LOCK_RES_IN_PROGRESS |
 676                                           DLM_LOCK_RES_RECOVERING)) {
 677                                 /* move it to the tail and keep going */
 678                                 res->state &= ~DLM_LOCK_RES_DIRTY;
 679                                 spin_unlock(&res->spinlock);
 680                                 mlog(0, "delaying list shuffling for in-"
 681                                      "progress lockres %.*s, state=%d\n",
 682                                      res->lockname.len, res->lockname.name,
 683                                      res->state);
 684                                 delay = 1;
 685                                 goto in_progress;
 686                         }
 687
 688                         /* at this point the lockres is not migrating/
 689                          * recovering/in-progress.  we have the lockres
 690                          * spinlock and do NOT have the dlm lock.
 691                          * safe to reserve/queue asts and run the lists. */
 692
 693                         mlog(0, "calling dlm_shuffle_lists with dlm=%s, "
 694                              "res=%.*s\n", dlm->name,
 695                              res->lockname.len, res->lockname.name);
 696
 697                         /* called while holding lockres lock */
 698                         dlm_shuffle_lists(dlm, res);
 699                         res->state &= ~DLM_LOCK_RES_DIRTY;
 700                         spin_unlock(&res->spinlock);
 701
 702                         dlm_lockres_calc_usage(dlm, res);
 703
 704 in_progress:
 705
 706                         spin_lock(&dlm->spinlock);
 707                         /* if the lock was in-progress, stick
 708                          * it on the back of the list */
 709                         if (delay) {
 710                                 spin_lock(&res->spinlock);
 711                                 __dlm_dirty_lockres(dlm, res);
 712                                 spin_unlock(&res->spinlock);
 713                         }
 714                         dlm_lockres_put(res);
 715
 716                         /* unlikely, but we may need to give time to
 717                          * other tasks */
 718                         if (!--n) {
 719                                 mlog(0, "throttling dlm_thread\n");
 720                                 break;
 721                         }
 722                 }
 723
 724                 spin_unlock(&dlm->spinlock);
 725                 dlm_flush_asts(dlm);
 726
 727                 /* yield and continue right away if there is more work to do */
 728                 if (!n) {
 729                         cond_resched();
 730                         continue;
 731                 }
 732
 733                 wait_event_interruptible_timeout(dlm->dlm_thread_wq,
 734                                                  !dlm_dirty_list_empty(dlm) ||
 735                                                  kthread_should_stop(),
 736                                                  timeout);
 737         }
 738
 739         mlog(0, "quitting DLM thread\n");
 740         return 0;
 741 }