Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * dlmthread.c
 *
 * standalone DLM module
 *
 * Copyright (C) 2004 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 *
 */


#include <linux/module.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/highmem.h>
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/random.h>
#include <linux/blkdev.h>
#include <linux/socket.h>
#include <linux/inet.h>
#include <linux/timer.h>
#include <linux/kthread.h>
#include <linux/delay.h>


#include "cluster/heartbeat.h"
#include "cluster/nodemanager.h"
#include "cluster/tcp.h"

#include "dlmapi.h"
#include "dlmcommon.h"
#include "dlmdomain.h"

#define MLOG_MASK_PREFIX (ML_DLM|ML_DLM_THREAD)
#include "cluster/masklog.h"

static int dlm_thread(void *data);
static void dlm_flush_asts(struct dlm_ctxt *dlm);

#define dlm_lock_is_remote(dlm, lock)     ((lock)->ml.node != (dlm)->node_num)

/* will exit holding res->spinlock, but may drop in function */
/* waits until flags are cleared on res->state */
void __dlm_wait_on_lockres_flags(struct dlm_lock_resource *res, int flags)
{
	DECLARE_WAITQUEUE(wait, current);

	assert_spin_locked(&res->spinlock);

	add_wait_queue(&res->wq, &wait);
repeat:
	set_current_state(TASK_UNINTERRUPTIBLE);
	if (res->state & flags) {
		spin_unlock(&res->spinlock);
		schedule();
		spin_lock(&res->spinlock);
		goto repeat;
	}
	remove_wait_queue(&res->wq, &wait);
	__set_current_state(TASK_RUNNING);
}

int __dlm_lockres_has_locks(struct dlm_lock_resource *res)
{
	if (list_empty(&res->granted) &&
	    list_empty(&res->converting) &&
	    list_empty(&res->blocked))
		return 0;
	return 1;
}

/* "unused": the lockres has no locks, is not on the dirty list,
 * has no inflight locks (in the gap between mastery and acquiring
 * the first lock), and has no bits in its refmap.
 * truly ready to be freed. */
int __dlm_lockres_unused(struct dlm_lock_resource *res)
{
	int bit;

	assert_spin_locked(&res->spinlock);

	if (__dlm_lockres_has_locks(res))
		return 0;

	/* Locks are in the process of being created */
	if (res->inflight_locks)
		return 0;

	if (!list_empty(&res->dirty) || res->state & DLM_LOCK_RES_DIRTY)
		return 0;

	if (res->state & DLM_LOCK_RES_RECOVERING)
		return 0;

	/* Another node has this resource with this node as the master */
	bit = find_next_bit(res->refmap, O2NM_MAX_NODES, 0);
	if (bit < O2NM_MAX_NODES)
		return 0;

	return 1;
}


/* Call whenever you may have added or deleted something from one of
 * the lockres queue's. This will figure out whether it belongs on the
 * unused list or not and does the appropriate thing. */
void __dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
			      struct dlm_lock_resource *res)
{
	assert_spin_locked(&dlm->spinlock);
	assert_spin_locked(&res->spinlock);

	if (__dlm_lockres_unused(res)){
		if (list_empty(&res->purge)) {
			mlog(0, "%s: Adding res %.*s to purge list\n",
			     dlm->name, res->lockname.len, res->lockname.name);

			res->last_used = jiffies;
			dlm_lockres_get(res);
			list_add_tail(&res->purge, &dlm->purge_list);
			dlm->purge_count++;
		}
	} else if (!list_empty(&res->purge)) {
		mlog(0, "%s: Removing res %.*s from purge list\n",
		     dlm->name, res->lockname.len, res->lockname.name);

		list_del_init(&res->purge);
		dlm_lockres_put(res);
		dlm->purge_count--;
	}
}

void dlm_lockres_calc_usage(struct dlm_ctxt *dlm,
			    struct dlm_lock_resource *res)
{
	spin_lock(&dlm->spinlock);
	spin_lock(&res->spinlock);

	__dlm_lockres_calc_usage(dlm, res);

	spin_unlock(&res->spinlock);
	spin_unlock(&dlm->spinlock);
}

static void dlm_purge_lockres(struct dlm_ctxt *dlm,
			     struct dlm_lock_resource *res)
{
	int master;
	int ret = 0;

	assert_spin_locked(&dlm->spinlock);
	assert_spin_locked(&res->spinlock);

	master = (res->owner == dlm->node_num);

	mlog(0, "%s: Purging res %.*s, master %d\n", dlm->name,
	     res->lockname.len, res->lockname.name, master);

	if (!master) {
		res->state |= DLM_LOCK_RES_DROPPING_REF;
		/* drop spinlock...  retake below */
		spin_unlock(&res->spinlock);
		spin_unlock(&dlm->spinlock);

		spin_lock(&res->spinlock);
		/* This ensures that clear refmap is sent after the set */
		__dlm_wait_on_lockres_flags(res, DLM_LOCK_RES_SETREF_INPROG);
		spin_unlock(&res->spinlock);

		/* clear our bit from the master's refmap, ignore errors */
		ret = dlm_drop_lockres_ref(dlm, res);
		if (ret < 0) {
			if (!dlm_is_host_down(ret))
				BUG();
		}
		spin_lock(&dlm->spinlock);
		spin_lock(&res->spinlock);
	}

	if (!list_empty(&res->purge)) {
		mlog(0, "%s: Removing res %.*s from purgelist, master %d\n",
		     dlm->name, res->lockname.len, res->lockname.name, master);
		list_del_init(&res->purge);
		dlm_lockres_put(res);
		dlm->purge_count--;
	}

	if (!__dlm_lockres_unused(res)) {
		mlog(ML_ERROR, "%s: res %.*s in use after deref\n",
		     dlm->name, res->lockname.len, res->lockname.name);
		__dlm_print_one_lock_resource(res);
		BUG();
	}

	__dlm_unhash_lockres(dlm, res);

	spin_lock(&dlm->track_lock);
	if (!list_empty(&res->tracking))
		list_del_init(&res->tracking);
	else {
		mlog(ML_ERROR, "Resource %.*s not on the Tracking list\n",
				res->lockname.len, res->lockname.name);
		__dlm_print_one_lock_resource(res);
	}
	spin_unlock(&dlm->track_lock);

	/* lockres is not in the hash now.  drop the flag and wake up
	 * any processes waiting in dlm_get_lock_resource. */
	if (!master) {
		res->state &= ~DLM_LOCK_RES_DROPPING_REF;
		spin_unlock(&res->spinlock);
		wake_up(&res->wq);
	} else
		spin_unlock(&res->spinlock);
}

static void dlm_run_purge_list(struct dlm_ctxt *dlm,
			       int purge_now)
{
	unsigned int run_max, unused;
	unsigned long purge_jiffies;
	struct dlm_lock_resource *lockres;

	spin_lock(&dlm->spinlock);
	run_max = dlm->purge_count;

	while(run_max && !list_empty(&dlm->purge_list)) {
		run_max--;

		lockres = list_entry(dlm->purge_list.next,
				     struct dlm_lock_resource, purge);

		spin_lock(&lockres->spinlock);

		purge_jiffies = lockres->last_used +
			msecs_to_jiffies(DLM_PURGE_INTERVAL_MS);

		/* Make sure that we want to be processing this guy at
		 * this time. */
		if (!purge_now && time_after(purge_jiffies, jiffies)) {
			/* Since resources are added to the purge list
			 * in tail order, we can stop at the first
			 * unpurgable resource -- anyone added after
			 * him will have a greater last_used value */
			spin_unlock(&lockres->spinlock);
			break;
		}

		/* Status of the lockres *might* change so double
		 * check. If the lockres is unused, holding the dlm
		 * spinlock will prevent people from getting and more
		 * refs on it. */
		unused = __dlm_lockres_unused(lockres);
		if (!unused ||
		    (lockres->state & DLM_LOCK_RES_MIGRATING) ||
		    (lockres->inflight_assert_workers != 0)) {
			mlog(0, "%s: res %.*s is in use or being remastered, "
			     "used %d, state %d, assert master workers %u\n",
			     dlm->name, lockres->lockname.len,
			     lockres->lockname.name,
			     !unused, lockres->state,
			     lockres->inflight_assert_workers);
			list_move_tail(&lockres->purge, &dlm->purge_list);
			spin_unlock(&lockres->spinlock);
			continue;
		}

		dlm_lockres_get(lockres);

		dlm_purge_lockres(dlm, lockres);

		dlm_lockres_put(lockres);

		/* Avoid adding any scheduling latencies */
		cond_resched_lock(&dlm->spinlock);
	}

	spin_unlock(&dlm->spinlock);
}

static void dlm_shuffle_lists(struct dlm_ctxt *dlm,
			      struct dlm_lock_resource *res)
{
	struct dlm_lock *lock, *target;
	int can_grant = 1;

	/*
	 * Because this function is called with the lockres
	 * spinlock, and because we know that it is not migrating/
	 * recovering/in-progress, it is fine to reserve asts and
	 * basts right before queueing them all throughout
	 */
	assert_spin_locked(&dlm->ast_lock);
	assert_spin_locked(&res->spinlock);
	BUG_ON((res->state & (DLM_LOCK_RES_MIGRATING|
			      DLM_LOCK_RES_RECOVERING|
			      DLM_LOCK_RES_IN_PROGRESS)));

converting:
	if (list_empty(&res->converting))
		goto blocked;
	mlog(0, "%s: res %.*s has locks on the convert queue\n", dlm->name,
	     res->lockname.len, res->lockname.name);

	target = list_entry(res->converting.next, struct dlm_lock, list);
	if (target->ml.convert_type == LKM_IVMODE) {
		mlog(ML_ERROR, "%s: res %.*s converting lock to invalid mode\n",
		     dlm->name, res->lockname.len, res->lockname.name);
		BUG();
	}
	list_for_each_entry(lock, &res->granted, list) {
		if (lock==target)
			continue;
		if (!dlm_lock_compatible(lock->ml.type,
					 target->ml.convert_type)) {
			can_grant = 0;
			/* queue the BAST if not already */
			if (lock->ml.highest_blocked == LKM_IVMODE) {
				__dlm_lockres_reserve_ast(res);
				__dlm_queue_bast(dlm, lock);
			}
			/* update the highest_blocked if needed */
			if (lock->ml.highest_blocked < target->ml.convert_type)
				lock->ml.highest_blocked =
					target->ml.convert_type;
		}
	}

	list_for_each_entry(lock, &res->converting, list) {
		if (lock==target)
			continue;
		if (!dlm_lock_compatible(lock->ml.type,
					 target->ml.convert_type)) {
			can_grant = 0;
			if (lock->ml.highest_blocked == LKM_IVMODE) {
				__dlm_lockres_reserve_ast(res);
				__dlm_queue_bast(dlm, lock);
			}
			if (lock->ml.highest_blocked < target->ml.convert_type)
				lock->ml.highest_blocked =
					target->ml.convert_type;
		}
	}

	/* we can convert the lock */
	if (can_grant) {
		spin_lock(&target->spinlock);
		BUG_ON(target->ml.highest_blocked != LKM_IVMODE);

		mlog(0, "%s: res %.*s, AST for Converting lock %u:%llu, type "
		     "%d => %d, node %u\n", dlm->name, res->lockname.len,
		     res->lockname.name,
		     dlm_get_lock_cookie_node(be64_to_cpu(target->ml.cookie)),
		     dlm_get_lock_cookie_seq(be64_to_cpu(target->ml.cookie)),
		     target->ml.type,
		     target->ml.convert_type, target->ml.node);

		target->ml.type = target->ml.convert_type;
		target->ml.convert_type = LKM_IVMODE;
		list_move_tail(&target->list, &res->granted);

		BUG_ON(!target->lksb);
		target->lksb->status = DLM_NORMAL;

		spin_unlock(&target->spinlock);

		__dlm_lockres_reserve_ast(res);
		__dlm_queue_ast(dlm, target);
		/* go back and check for more */
		goto converting;
	}

blocked:
	if (list_empty(&res->blocked))
		goto leave;
	target = list_entry(res->blocked.next, struct dlm_lock, list);

	list_for_each_entry(lock, &res->granted, list) {
		if (lock==target)
			continue;
		if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
			can_grant = 0;
			if (lock->ml.highest_blocked == LKM_IVMODE) {
				__dlm_lockres_reserve_ast(res);
				__dlm_queue_bast(dlm, lock);
			}
			if (lock->ml.highest_blocked < target->ml.type)
				lock->ml.highest_blocked = target->ml.type;
		}
	}

	list_for_each_entry(lock, &res->converting, list) {
		if (lock==target)
			continue;
		if (!dlm_lock_compatible(lock->ml.type, target->ml.type)) {
			can_grant = 0;
			if (lock->ml.highest_blocked == LKM_IVMODE) {
				__dlm_lockres_reserve_ast(res);
				__dlm_queue_bast(dlm, lock);
			}
			if (lock->ml.highest_blocked < target->ml.type)
				lock->ml.highest_blocked = target->ml.type;
		}
	}

	/* we can grant the blocked lock (only
	 * possible if converting list empty) */
	if (can_grant) {
		spin_lock(&target->spinlock);
		BUG_ON(target->ml.highest_blocked != LKM_IVMODE);

		mlog(0, "%s: res %.*s, AST for Blocked lock %u:%llu, type %d, "
		     "node %u\n", dlm->name, res->lockname.len,
		     res->lockname.name,
		     dlm_get_lock_cookie_node(be64_to_cpu(target->ml.cookie)),
		     dlm_get_lock_cookie_seq(be64_to_cpu(target->ml.cookie)),
		     target->ml.type, target->ml.node);

		/* target->ml.type is already correct */
		list_move_tail(&target->list, &res->granted);

		BUG_ON(!target->lksb);
		target->lksb->status = DLM_NORMAL;

		spin_unlock(&target->spinlock);

		__dlm_lockres_reserve_ast(res);
		__dlm_queue_ast(dlm, target);
		/* go back and check for more */
		goto converting;
	}

leave:
	return;
}

/* must have NO locks when calling this with res !=NULL * */
void dlm_kick_thread(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
{
	if (res) {
		spin_lock(&dlm->spinlock);
		spin_lock(&res->spinlock);
		__dlm_dirty_lockres(dlm, res);
		spin_unlock(&res->spinlock);
		spin_unlock(&dlm->spinlock);
	}
	wake_up(&dlm->dlm_thread_wq);
}

void __dlm_dirty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
{
	assert_spin_locked(&dlm->spinlock);
	assert_spin_locked(&res->spinlock);

	/* don't shuffle secondary queues */
	if ((res->owner == dlm->node_num)) {
		if (res->state & (DLM_LOCK_RES_MIGRATING |
				  DLM_LOCK_RES_BLOCK_DIRTY))
		    return;

		if (list_empty(&res->dirty)) {
			/* ref for dirty_list */
			dlm_lockres_get(res);
			list_add_tail(&res->dirty, &dlm->dirty_list);
			res->state |= DLM_LOCK_RES_DIRTY;
		}
	}

	mlog(0, "%s: res %.*s\n", dlm->name, res->lockname.len,
	     res->lockname.name);
}


/* Launch the NM thread for the mounted volume */
int dlm_launch_thread(struct dlm_ctxt *dlm)
{
	mlog(0, "Starting dlm_thread...\n");

	dlm->dlm_thread_task = kthread_run(dlm_thread, dlm, "dlm-%s",
			dlm->name);
	if (IS_ERR(dlm->dlm_thread_task)) {
		mlog_errno(PTR_ERR(dlm->dlm_thread_task));
		dlm->dlm_thread_task = NULL;
		return -EINVAL;
	}

	return 0;
}

void dlm_complete_thread(struct dlm_ctxt *dlm)
{
	if (dlm->dlm_thread_task) {
		mlog(ML_KTHREAD, "Waiting for dlm thread to exit\n");
		kthread_stop(dlm->dlm_thread_task);
		dlm->dlm_thread_task = NULL;
	}
}

static int dlm_dirty_list_empty(struct dlm_ctxt *dlm)
{
	int empty;

	spin_lock(&dlm->spinlock);
	empty = list_empty(&dlm->dirty_list);
	spin_unlock(&dlm->spinlock);

	return empty;
}

static void dlm_flush_asts(struct dlm_ctxt *dlm)
{
	int ret;
	struct dlm_lock *lock;
	struct dlm_lock_resource *res;
	u8 hi;

	spin_lock(&dlm->ast_lock);
	while (!list_empty(&dlm->pending_asts)) {
		lock = list_entry(dlm->pending_asts.next,
				  struct dlm_lock, ast_list);
		/* get an extra ref on lock */
		dlm_lock_get(lock);
		res = lock->lockres;
		mlog(0, "%s: res %.*s, Flush AST for lock %u:%llu, type %d, "
		     "node %u\n", dlm->name, res->lockname.len,
		     res->lockname.name,
		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
		     lock->ml.type, lock->ml.node);

		BUG_ON(!lock->ast_pending);

		/* remove from list (including ref) */
		list_del_init(&lock->ast_list);
		dlm_lock_put(lock);
		spin_unlock(&dlm->ast_lock);

		if (lock->ml.node != dlm->node_num) {
			ret = dlm_do_remote_ast(dlm, res, lock);
			if (ret < 0)
				mlog_errno(ret);
		} else
			dlm_do_local_ast(dlm, res, lock);

		spin_lock(&dlm->ast_lock);

		/* possible that another ast was queued while
		 * we were delivering the last one */
		if (!list_empty(&lock->ast_list)) {
			mlog(0, "%s: res %.*s, AST queued while flushing last "
			     "one\n", dlm->name, res->lockname.len,
			     res->lockname.name);
		} else
			lock->ast_pending = 0;

		/* drop the extra ref.
		 * this may drop it completely. */
		dlm_lock_put(lock);
		dlm_lockres_release_ast(dlm, res);
	}

	while (!list_empty(&dlm->pending_basts)) {
		lock = list_entry(dlm->pending_basts.next,
				  struct dlm_lock, bast_list);
		/* get an extra ref on lock */
		dlm_lock_get(lock);
		res = lock->lockres;

		BUG_ON(!lock->bast_pending);

		/* get the highest blocked lock, and reset */
		spin_lock(&lock->spinlock);
		BUG_ON(lock->ml.highest_blocked <= LKM_IVMODE);
		hi = lock->ml.highest_blocked;
		lock->ml.highest_blocked = LKM_IVMODE;
		spin_unlock(&lock->spinlock);

		/* remove from list (including ref) */
		list_del_init(&lock->bast_list);
		dlm_lock_put(lock);
		spin_unlock(&dlm->ast_lock);

		mlog(0, "%s: res %.*s, Flush BAST for lock %u:%llu, "
		     "blocked %d, node %u\n",
		     dlm->name, res->lockname.len, res->lockname.name,
		     dlm_get_lock_cookie_node(be64_to_cpu(lock->ml.cookie)),
		     dlm_get_lock_cookie_seq(be64_to_cpu(lock->ml.cookie)),
		     hi, lock->ml.node);

		if (lock->ml.node != dlm->node_num) {
			ret = dlm_send_proxy_bast(dlm, res, lock, hi);
			if (ret < 0)
				mlog_errno(ret);
		} else
			dlm_do_local_bast(dlm, res, lock, hi);

		spin_lock(&dlm->ast_lock);

		/* possible that another bast was queued while
		 * we were delivering the last one */
		if (!list_empty(&lock->bast_list)) {
			mlog(0, "%s: res %.*s, BAST queued while flushing last "
			     "one\n", dlm->name, res->lockname.len,
			     res->lockname.name);
		} else
			lock->bast_pending = 0;

		/* drop the extra ref.
		 * this may drop it completely. */
		dlm_lock_put(lock);
		dlm_lockres_release_ast(dlm, res);
	}
	wake_up(&dlm->ast_wq);
	spin_unlock(&dlm->ast_lock);
}


#define DLM_THREAD_TIMEOUT_MS (4 * 1000)
#define DLM_THREAD_MAX_DIRTY  100
#define DLM_THREAD_MAX_ASTS   10

static int dlm_thread(void *data)
{
	struct dlm_lock_resource *res;
	struct dlm_ctxt *dlm = data;
	unsigned long timeout = msecs_to_jiffies(DLM_THREAD_TIMEOUT_MS);

	mlog(0, "dlm thread running for %s...\n", dlm->name);

	while (!kthread_should_stop()) {
		int n = DLM_THREAD_MAX_DIRTY;

		/* dlm_shutting_down is very point-in-time, but that
		 * doesn't matter as we'll just loop back around if we
		 * get false on the leading edge of a state
		 * transition. */
		dlm_run_purge_list(dlm, dlm_shutting_down(dlm));

		/* We really don't want to hold dlm->spinlock while
		 * calling dlm_shuffle_lists on each lockres that
		 * needs to have its queues adjusted and AST/BASTs
		 * run.  So let's pull each entry off the dirty_list
		 * and drop dlm->spinlock ASAP.  Once off the list,
		 * res->spinlock needs to be taken again to protect
		 * the queues while calling dlm_shuffle_lists.  */
		spin_lock(&dlm->spinlock);
		while (!list_empty(&dlm->dirty_list)) {
			int delay = 0;
			res = list_entry(dlm->dirty_list.next,
					 struct dlm_lock_resource, dirty);

			/* peel a lockres off, remove it from the list,
			 * unset the dirty flag and drop the dlm lock */
			BUG_ON(!res);
			dlm_lockres_get(res);

			spin_lock(&res->spinlock);
			/* We clear the DLM_LOCK_RES_DIRTY state once we shuffle lists below */
			list_del_init(&res->dirty);
			spin_unlock(&res->spinlock);
			spin_unlock(&dlm->spinlock);
			/* Drop dirty_list ref */
			dlm_lockres_put(res);

		 	/* lockres can be re-dirtied/re-added to the
			 * dirty_list in this gap, but that is ok */

			spin_lock(&dlm->ast_lock);
			spin_lock(&res->spinlock);
			if (res->owner != dlm->node_num) {
				__dlm_print_one_lock_resource(res);
				mlog(ML_ERROR, "%s: inprog %d, mig %d, reco %d,"
				     " dirty %d\n", dlm->name,
				     !!(res->state & DLM_LOCK_RES_IN_PROGRESS),
				     !!(res->state & DLM_LOCK_RES_MIGRATING),
				     !!(res->state & DLM_LOCK_RES_RECOVERING),
				     !!(res->state & DLM_LOCK_RES_DIRTY));
			}
			BUG_ON(res->owner != dlm->node_num);

			/* it is now ok to move lockreses in these states
			 * to the dirty list, assuming that they will only be
			 * dirty for a short while. */
			BUG_ON(res->state & DLM_LOCK_RES_MIGRATING);
			if (res->state & (DLM_LOCK_RES_IN_PROGRESS |
					  DLM_LOCK_RES_RECOVERING)) {
				/* move it to the tail and keep going */
				res->state &= ~DLM_LOCK_RES_DIRTY;
				spin_unlock(&res->spinlock);
				spin_unlock(&dlm->ast_lock);
				mlog(0, "%s: res %.*s, inprogress, delay list "
				     "shuffle, state %d\n", dlm->name,
				     res->lockname.len, res->lockname.name,
				     res->state);
				delay = 1;
				goto in_progress;
			}

			/* at this point the lockres is not migrating/
			 * recovering/in-progress.  we have the lockres
			 * spinlock and do NOT have the dlm lock.
			 * safe to reserve/queue asts and run the lists. */

			/* called while holding lockres lock */
			dlm_shuffle_lists(dlm, res);
			res->state &= ~DLM_LOCK_RES_DIRTY;
			spin_unlock(&res->spinlock);
			spin_unlock(&dlm->ast_lock);

			dlm_lockres_calc_usage(dlm, res);

in_progress:

			spin_lock(&dlm->spinlock);
			/* if the lock was in-progress, stick
			 * it on the back of the list */
			if (delay) {
				spin_lock(&res->spinlock);
				__dlm_dirty_lockres(dlm, res);
				spin_unlock(&res->spinlock);
			}
			dlm_lockres_put(res);

			/* unlikely, but we may need to give time to
			 * other tasks */
			if (!--n) {
				mlog(0, "%s: Throttling dlm thread\n",
				     dlm->name);
				break;
			}
		}

		spin_unlock(&dlm->spinlock);
		dlm_flush_asts(dlm);

		/* yield and continue right away if there is more work to do */
		if (!n) {
			cond_resched();
			continue;
		}

		wait_event_interruptible_timeout(dlm->dlm_thread_wq,
						 !dlm_dirty_list_empty(dlm) ||
						 kthread_should_stop(),
						 timeout);
	}

	mlog(0, "quitting DLM thread\n");
	return 0;
}