aboutsummaryrefslogtreecommitdiff
path: root/fs/gfs2/lock_dlm.c
blob: ac7caa267ed6090c1f4f3f18293399783162a021 (plain)
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
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright 2004-2011 Red Hat, Inc.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/fs.h>
#include <linux/dlm.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/delay.h>
#include <linux/gfs2_ondisk.h>
#include <linux/sched/signal.h>

#include "incore.h"
#include "glock.h"
#include "util.h"
#include "sys.h"
#include "trace_gfs2.h"

/**
 * gfs2_update_stats - Update time based stats
 * @mv: Pointer to mean/variance structure to update
 * @sample: New data to include
 *
 * @delta is the difference between the current rtt sample and the
 * running average srtt. We add 1/8 of that to the srtt in order to
 * update the current srtt estimate. The variance estimate is a bit
 * more complicated. We subtract the abs value of the @delta from
 * the current variance estimate and add 1/4 of that to the running
 * total.
 *
 * Note that the index points at the array entry containing the smoothed
 * mean value, and the variance is always in the following entry
 *
 * Reference: TCP/IP Illustrated, vol 2, p. 831,832
 * All times are in units of integer nanoseconds. Unlike the TCP/IP case,
 * they are not scaled fixed point.
 */

static inline void gfs2_update_stats(struct gfs2_lkstats *s, unsigned index,
				     s64 sample)
{
	s64 delta = sample - s->stats[index];
	s->stats[index] += (delta >> 3);
	index++;
	s->stats[index] += ((abs(delta) - s->stats[index]) >> 2);
}

/**
 * gfs2_update_reply_times - Update locking statistics
 * @gl: The glock to update
 *
 * This assumes that gl->gl_dstamp has been set earlier.
 *
 * The rtt (lock round trip time) is an estimate of the time
 * taken to perform a dlm lock request. We update it on each
 * reply from the dlm.
 *
 * The blocking flag is set on the glock for all dlm requests
 * which may potentially block due to lock requests from other nodes.
 * DLM requests where the current lock state is exclusive, the
 * requested state is null (or unlocked) or where the TRY or
 * TRY_1CB flags are set are classified as non-blocking. All
 * other DLM requests are counted as (potentially) blocking.
 */
static inline void gfs2_update_reply_times(struct gfs2_glock *gl)
{
	struct gfs2_pcpu_lkstats *lks;
	const unsigned gltype = gl->gl_name.ln_type;
	unsigned index = test_bit(GLF_BLOCKING, &gl->gl_flags) ?
			 GFS2_LKS_SRTTB : GFS2_LKS_SRTT;
	s64 rtt;

	preempt_disable();
	rtt = ktime_to_ns(ktime_sub(ktime_get_real(), gl->gl_dstamp));
	lks = this_cpu_ptr(gl->gl_name.ln_sbd->sd_lkstats);
	gfs2_update_stats(&gl->gl_stats, index, rtt);		/* Local */
	gfs2_update_stats(&lks->lkstats[gltype], index, rtt);	/* Global */
	preempt_enable();

	trace_gfs2_glock_lock_time(gl, rtt);
}

/**
 * gfs2_update_request_times - Update locking statistics
 * @gl: The glock to update
 *
 * The irt (lock inter-request times) measures the average time
 * between requests to the dlm. It is updated immediately before
 * each dlm call.
 */

static inline void gfs2_update_request_times(struct gfs2_glock *gl)
{
	struct gfs2_pcpu_lkstats *lks;
	const unsigned gltype = gl->gl_name.ln_type;
	ktime_t dstamp;
	s64 irt;

	preempt_disable();
	dstamp = gl->gl_dstamp;
	gl->gl_dstamp = ktime_get_real();
	irt = ktime_to_ns(ktime_sub(gl->gl_dstamp, dstamp));
	lks = this_cpu_ptr(gl->gl_name.ln_sbd->sd_lkstats);
	gfs2_update_stats(&gl->gl_stats, GFS2_LKS_SIRT, irt);		/* Local */
	gfs2_update_stats(&lks->lkstats[gltype], GFS2_LKS_SIRT, irt);	/* Global */
	preempt_enable();
}
 
static void gdlm_ast(void *arg)
{
	struct gfs2_glock *gl = arg;
	unsigned ret = gl->gl_state;

	gfs2_update_reply_times(gl);
	BUG_ON(gl->gl_lksb.sb_flags & DLM_SBF_DEMOTED);

	if ((gl->gl_lksb.sb_flags & DLM_SBF_VALNOTVALID) && gl->gl_lksb.sb_lvbptr)
		memset(gl->gl_lksb.sb_lvbptr, 0, GDLM_LVB_SIZE);

	switch (gl->gl_lksb.sb_status) {
	case -DLM_EUNLOCK: /* Unlocked, so glock can be freed */
		gfs2_glock_free(gl);
		return;
	case -DLM_ECANCEL: /* Cancel while getting lock */
		ret |= LM_OUT_CANCELED;
		goto out;
	case -EAGAIN: /* Try lock fails */
	case -EDEADLK: /* Deadlock detected */
		goto out;
	case -ETIMEDOUT: /* Canceled due to timeout */
		ret |= LM_OUT_ERROR;
		goto out;
	case 0: /* Success */
		break;
	default: /* Something unexpected */
		BUG();
	}

	ret = gl->gl_req;
	if (gl->gl_lksb.sb_flags & DLM_SBF_ALTMODE) {
		if (gl->gl_req == LM_ST_SHARED)
			ret = LM_ST_DEFERRED;
		else if (gl->gl_req == LM_ST_DEFERRED)
			ret = LM_ST_SHARED;
		else
			BUG();
	}

	set_bit(GLF_INITIAL, &gl->gl_flags);
	gfs2_glock_complete(gl, ret);
	return;
out:
	if (!test_bit(GLF_INITIAL, &gl->gl_flags))
		gl->gl_lksb.sb_lkid = 0;
	gfs2_glock_complete(gl, ret);
}

static void gdlm_bast(void *arg, int mode)
{
	struct gfs2_glock *gl = arg;

	switch (mode) {
	case DLM_LOCK_EX:
		gfs2_glock_cb(gl, LM_ST_UNLOCKED);
		break;
	case DLM_LOCK_CW:
		gfs2_glock_cb(gl, LM_ST_DEFERRED);
		break;
	case DLM_LOCK_PR:
		gfs2_glock_cb(gl, LM_ST_SHARED);
		break;
	default:
		pr_err("unknown bast mode %d\n", mode);
		BUG();
	}
}

/* convert gfs lock-state to dlm lock-mode */

static int make_mode(const unsigned int lmstate)
{
	switch (lmstate) {
	case LM_ST_UNLOCKED:
		return DLM_LOCK_NL;
	case LM_ST_EXCLUSIVE:
		return DLM_LOCK_EX;
	case LM_ST_DEFERRED:
		return DLM_LOCK_CW;
	case LM_ST_SHARED:
		return DLM_LOCK_PR;
	}
	pr_err("unknown LM state %d\n", lmstate);
	BUG();
	return -1;
}

static u32 make_flags(struct gfs2_glock *gl, const unsigned int gfs_flags,
		      const int req)
{
	u32 lkf = 0;

	if (gl->gl_lksb.sb_lvbptr)
		lkf |= DLM_LKF_VALBLK;

	if (gfs_flags & LM_FLAG_TRY)
		lkf |= DLM_LKF_NOQUEUE;

	if (gfs_flags & LM_FLAG_TRY_1CB) {
		lkf |= DLM_LKF_NOQUEUE;
		lkf |= DLM_LKF_NOQUEUEBAST;
	}

	if (gfs_flags & LM_FLAG_PRIORITY) {
		lkf |= DLM_LKF_NOORDER;
		lkf |= DLM_LKF_HEADQUE;
	}

	if (gfs_flags & LM_FLAG_ANY) {
		if (req == DLM_LOCK_PR)
			lkf |= DLM_LKF_ALTCW;
		else if (req == DLM_LOCK_CW)
			lkf |= DLM_LKF_ALTPR;
		else
			BUG();
	}

	if (gl->gl_lksb.sb_lkid != 0) {
		lkf |= DLM_LKF_CONVERT;
		if (test_bit(GLF_BLOCKING, &gl->gl_flags))
			lkf |= DLM_LKF_QUECVT;
	}

	return lkf;
}

static void gfs2_reverse_hex(char *c, u64 value)
{
	*c = '0';
	while (value) {
		*c-- = hex_asc[value & 0x0f];
		value >>= 4;
	}
}

static int gdlm_lock(struct gfs2_glock *gl, unsigned int req_state,
		     unsigned int flags)
{
	struct lm_lockstruct *ls = &gl->gl_name.ln_sbd->sd_lockstruct;
	int req;
	u32 lkf;
	char strname[GDLM_STRNAME_BYTES] = "";

	req = make_mode(req_state);
	lkf = make_flags(gl, flags, req);
	gfs2_glstats_inc(gl, GFS2_LKS_DCOUNT);
	gfs2_sbstats_inc(gl, GFS2_LKS_DCOUNT);
	if (gl->gl_lksb.sb_lkid) {
		gfs2_update_request_times(gl);
	} else {
		memset(strname, ' ', GDLM_STRNAME_BYTES - 1);
		strname[GDLM_STRNAME_BYTES - 1] = '\0';
		gfs2_reverse_hex(strname + 7, gl->gl_name.ln_type);
		gfs2_reverse_hex(strname + 23, gl->gl_name.ln_number);
		gl->gl_dstamp = ktime_get_real();
	}
	/*
	 * Submit the actual lock request.
	 */

	return dlm_lock(ls->ls_dlm, req, &gl->gl_lksb, lkf, strname,
			GDLM_STRNAME_BYTES - 1, 0, gdlm_ast, gl, gdlm_bast);
}

static void gdlm_put_lock(struct gfs2_glock *gl)
{
	struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	int lvb_needs_unlock = 0;
	int error;

	if (gl->gl_lksb.sb_lkid == 0) {
		gfs2_glock_free(gl);
		return;
	}

	clear_bit(GLF_BLOCKING, &gl->gl_flags);
	gfs2_glstats_inc(gl, GFS2_LKS_DCOUNT);
	gfs2_sbstats_inc(gl, GFS2_LKS_DCOUNT);
	gfs2_update_request_times(gl);

	/* don't want to skip dlm_unlock writing the lvb when lock is ex */

	if (gl->gl_lksb.sb_lvbptr && (gl->gl_state == LM_ST_EXCLUSIVE))
		lvb_needs_unlock = 1;

	if (test_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags) &&
	    !lvb_needs_unlock) {
		gfs2_glock_free(gl);
		return;
	}

	error = dlm_unlock(ls->ls_dlm, gl->gl_lksb.sb_lkid, DLM_LKF_VALBLK,
			   NULL, gl);
	if (error) {
		pr_err("gdlm_unlock %x,%llx err=%d\n",
		       gl->gl_name.ln_type,
		       (unsigned long long)gl->gl_name.ln_number, error);
		return;
	}
}

static void gdlm_cancel(struct gfs2_glock *gl)
{
	struct lm_lockstruct *ls = &gl->gl_name.ln_sbd->sd_lockstruct;
	dlm_unlock(ls->ls_dlm, gl->gl_lksb.sb_lkid, DLM_LKF_CANCEL, NULL, gl);
}

/*
 * dlm/gfs2 recovery coordination using dlm_recover callbacks
 *
 *  1. dlm_controld sees lockspace members change
 *  2. dlm_controld blocks dlm-kernel locking activity
 *  3. dlm_controld within dlm-kernel notifies gfs2 (recover_prep)
 *  4. dlm_controld starts and finishes its own user level recovery
 *  5. dlm_controld starts dlm-kernel dlm_recoverd to do kernel recovery
 *  6. dlm_recoverd notifies gfs2 of failed nodes (recover_slot)
 *  7. dlm_recoverd does its own lock recovery
 *  8. dlm_recoverd unblocks dlm-kernel locking activity
 *  9. dlm_recoverd notifies gfs2 when done (recover_done with new generation)
 * 10. gfs2_control updates control_lock lvb with new generation and jid bits
 * 11. gfs2_control enqueues journals for gfs2_recover to recover (maybe none)
 * 12. gfs2_recover dequeues and recovers journals of failed nodes
 * 13. gfs2_recover provides recovery results to gfs2_control (recovery_result)
 * 14. gfs2_control updates control_lock lvb jid bits for recovered journals
 * 15. gfs2_control unblocks normal locking when all journals are recovered
 *
 * - failures during recovery
 *
 * recover_prep() may set BLOCK_LOCKS (step 3) again before gfs2_control
 * clears BLOCK_LOCKS (step 15), e.g. another node fails while still
 * recovering for a prior failure.  gfs2_control needs a way to detect
 * this so it can leave BLOCK_LOCKS set in step 15.  This is managed using
 * the recover_block and recover_start values.
 *
 * recover_done() provides a new lockspace generation number each time it
 * is called (step 9).  This generation number is saved as recover_start.
 * When recover_prep() is called, it sets BLOCK_LOCKS and sets
 * recover_block = recover_start.  So, while recover_block is equal to
 * recover_start, BLOCK_LOCKS should remain set.  (recover_spin must
 * be held around the BLOCK_LOCKS/recover_block/recover_start logic.)
 *
 * - more specific gfs2 steps in sequence above
 *
 *  3. recover_prep sets BLOCK_LOCKS and sets recover_block = recover_start
 *  6. recover_slot records any failed jids (maybe none)
 *  9. recover_done sets recover_start = new generation number
 * 10. gfs2_control sets control_lock lvb = new gen + bits for failed jids
 * 12. gfs2_recover does journal recoveries for failed jids identified above
 * 14. gfs2_control clears control_lock lvb bits for recovered jids
 * 15. gfs2_control checks if recover_block == recover_start (step 3 occured
 *     again) then do nothing, otherwise if recover_start > recover_block
 *     then clear BLOCK_LOCKS.
 *
 * - parallel recovery steps across all nodes
 *
 * All nodes attempt to update the control_lock lvb with the new generation
 * number and jid bits, but only the first to get the control_lock EX will
 * do so; others will see that it's already done (lvb already contains new
 * generation number.)
 *
 * . All nodes get the same recover_prep/recover_slot/recover_done callbacks
 * . All nodes attempt to set control_lock lvb gen + bits for the new gen
 * . One node gets control_lock first and writes the lvb, others see it's done
 * . All nodes attempt to recover jids for which they see control_lock bits set
 * . One node succeeds for a jid, and that one clears the jid bit in the lvb
 * . All nodes will eventually see all lvb bits clear and unblock locks
 *
 * - is there a problem with clearing an lvb bit that should be set
 *   and missing a journal recovery?
 *
 * 1. jid fails
 * 2. lvb bit set for step 1
 * 3. jid recovered for step 1
 * 4. jid taken again (new mount)
 * 5. jid fails (for step 4)
 * 6. lvb bit set for step 5 (will already be set)
 * 7. lvb bit cleared for step 3
 *
 * This is not a problem because the failure in step 5 does not
 * require recovery, because the mount in step 4 could not have
 * progressed far enough to unblock locks and access the fs.  The
 * control_mount() function waits for all recoveries to be complete
 * for the latest lockspace generation before ever unblocking locks
 * and returning.  The mount in step 4 waits until the recovery in
 * step 1 is done.
 *
 * - special case of first mounter: first node to mount the fs
 *
 * The first node to mount a gfs2 fs needs to check all the journals
 * and recover any that need recovery before other nodes are allowed
 * to mount the fs.  (Others may begin mounting, but they must wait
 * for the first mounter to be done before taking locks on the fs
 * or accessing the fs.)  This has two parts:
 *
 * 1. The mounted_lock tells a node it's the first to mount the fs.
 * Each node holds the mounted_lock in PR while it's mounted.
 * Each node tries to acquire the mounted_lock in EX when it mounts.
 * If a node is granted the mounted_lock EX it means there are no
 * other mounted nodes (no PR locks exist), and it is the first mounter.
 * The mounted_lock is demoted to PR when first recovery is done, so
 * others will fail to get an EX lock, but will get a PR lock.
 *
 * 2. The control_lock blocks others in control_mount() while the first
 * mounter is doing first mount recovery of all journals.
 * A mounting node needs to acquire control_lock in EX mode before
 * it can proceed.  The first mounter holds control_lock in EX while doing
 * the first mount recovery, blocking mounts from other nodes, then demotes
 * control_lock to NL when it's done (others_may_mount/first_done),
 * allowing other nodes to continue mounting.
 *
 * first mounter:
 * control_lock EX/NOQUEUE success
 * mounted_lock EX/NOQUEUE success (no other PR, so no other mounters)
 * set first=1
 * do first mounter recovery
 * mounted_lock EX->PR
 * control_lock EX->NL, write lvb generation
 *
 * other mounter:
 * control_lock EX/NOQUEUE success (if fail -EAGAIN, retry)
 * mounted_lock EX/NOQUEUE fail -EAGAIN (expected due to other mounters PR)
 * mounted_lock PR/NOQUEUE success
 * read lvb generation
 * control_lock EX->NL
 * set first=0
 *
 * - mount during recovery
 *
 * If a node mounts while others are doing recovery (not first mounter),
 * the mounting node will get its initial recover_done() callback without
 * having seen any previous failures/callbacks.
 *
 * It must wait for all recoveries preceding its mount to be finished
 * before it unblocks locks.  It does this by repeating the "other mounter"
 * steps above until the lvb generation number is >= its mount generation
 * number (from initial recover_done) and all lvb bits are clear.
 *
 * - control_lock lvb format
 *
 * 4 bytes generation number: the latest dlm lockspace generation number
 * from recover_done callback.  Indicates the jid bitmap has been updated
 * to reflect all slot failures through that generation.
 * 4 bytes unused.
 * GDLM_LVB_SIZE-8 bytes of jid bit map. If bit N is set, it indicates
 * that jid N needs recovery.
 */

#define JID_BITMAP_OFFSET 8 /* 4 byte generation number + 4 byte unused */

static void control_lvb_read(struct lm_lockstruct *ls, uint32_t *lvb_gen,
			     char *lvb_bits)
{
	__le32 gen;
	memcpy(lvb_bits, ls->ls_control_lvb, GDLM_LVB_SIZE);
	memcpy(&gen, lvb_bits, sizeof(__le32));
	*lvb_gen = le32_to_cpu(gen);
}

static void control_lvb_write(struct lm_lockstruct *ls, uint32_t lvb_gen,
			      char *lvb_bits)
{
	__le32 gen;
	memcpy(ls->ls_control_lvb, lvb_bits, GDLM_LVB_SIZE);
	gen = cpu_to_le32(lvb_gen);
	memcpy(ls->ls_control_lvb, &gen, sizeof(__le32));
}

static int all_jid_bits_clear(char *lvb)
{
	return !memchr_inv(lvb + JID_BITMAP_OFFSET, 0,
			GDLM_LVB_SIZE - JID_BITMAP_OFFSET);
}

static void sync_wait_cb(void *arg)
{
	struct lm_lockstruct *ls = arg;
	complete(&ls->ls_sync_wait);
}

static int sync_unlock(struct gfs2_sbd *sdp, struct dlm_lksb *lksb, char *name)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	int error;

	error = dlm_unlock(ls->ls_dlm, lksb->sb_lkid, 0, lksb, ls);
	if (error) {
		fs_err(sdp, "%s lkid %x error %d\n",
		       name, lksb->sb_lkid, error);
		return error;
	}

	wait_for_completion(&ls->ls_sync_wait);

	if (lksb->sb_status != -DLM_EUNLOCK) {
		fs_err(sdp, "%s lkid %x status %d\n",
		       name, lksb->sb_lkid, lksb->sb_status);
		return -1;
	}
	return 0;
}

static int sync_lock(struct gfs2_sbd *sdp, int mode, uint32_t flags,
		     unsigned int num, struct dlm_lksb *lksb, char *name)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	char strname[GDLM_STRNAME_BYTES];
	int error, status;

	memset(strname, 0, GDLM_STRNAME_BYTES);
	snprintf(strname, GDLM_STRNAME_BYTES, "%8x%16x", LM_TYPE_NONDISK, num);

	error = dlm_lock(ls->ls_dlm, mode, lksb, flags,
			 strname, GDLM_STRNAME_BYTES - 1,
			 0, sync_wait_cb, ls, NULL);
	if (error) {
		fs_err(sdp, "%s lkid %x flags %x mode %d error %d\n",
		       name, lksb->sb_lkid, flags, mode, error);
		return error;
	}

	wait_for_completion(&ls->ls_sync_wait);

	status = lksb->sb_status;

	if (status && status != -EAGAIN) {
		fs_err(sdp, "%s lkid %x flags %x mode %d status %d\n",
		       name, lksb->sb_lkid, flags, mode, status);
	}

	return status;
}

static int mounted_unlock(struct gfs2_sbd *sdp)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	return sync_unlock(sdp, &ls->ls_mounted_lksb, "mounted_lock");
}

static int mounted_lock(struct gfs2_sbd *sdp, int mode, uint32_t flags)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	return sync_lock(sdp, mode, flags, GFS2_MOUNTED_LOCK,
			 &ls->ls_mounted_lksb, "mounted_lock");
}

static int control_unlock(struct gfs2_sbd *sdp)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	return sync_unlock(sdp, &ls->ls_control_lksb, "control_lock");
}

static int control_lock(struct gfs2_sbd *sdp, int mode, uint32_t flags)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	return sync_lock(sdp, mode, flags, GFS2_CONTROL_LOCK,
			 &ls->ls_control_lksb, "control_lock");
}

static void gfs2_control_func(struct work_struct *work)
{
	struct gfs2_sbd *sdp = container_of(work, struct gfs2_sbd, sd_control_work.work);
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	uint32_t block_gen, start_gen, lvb_gen, flags;
	int recover_set = 0;
	int write_lvb = 0;
	int recover_size;
	int i, error;

	spin_lock(&ls->ls_recover_spin);
	/*
	 * No MOUNT_DONE means we're still mounting; control_mount()
	 * will set this flag, after which this thread will take over
	 * all further clearing of BLOCK_LOCKS.
	 *
	 * FIRST_MOUNT means this node is doing first mounter recovery,
	 * for which recovery control is handled by
	 * control_mount()/control_first_done(), not this thread.
	 */
	if (!test_bit(DFL_MOUNT_DONE, &ls->ls_recover_flags) ||
	     test_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags)) {
		spin_unlock(&ls->ls_recover_spin);
		return;
	}
	block_gen = ls->ls_recover_block;
	start_gen = ls->ls_recover_start;
	spin_unlock(&ls->ls_recover_spin);

	/*
	 * Equal block_gen and start_gen implies we are between
	 * recover_prep and recover_done callbacks, which means
	 * dlm recovery is in progress and dlm locking is blocked.
	 * There's no point trying to do any work until recover_done.
	 */

	if (block_gen == start_gen)
		return;

	/*
	 * Propagate recover_submit[] and recover_result[] to lvb:
	 * dlm_recoverd adds to recover_submit[] jids needing recovery
	 * gfs2_recover adds to recover_result[] journal recovery results
	 *
	 * set lvb bit for jids in recover_submit[] if the lvb has not
	 * yet been updated for the generation of the failure
	 *
	 * clear lvb bit for jids in recover_result[] if the result of
	 * the journal recovery is SUCCESS
	 */

	error = control_lock(sdp, DLM_LOCK_EX, DLM_LKF_CONVERT|DLM_LKF_VALBLK);
	if (error) {
		fs_err(sdp, "control lock EX error %d\n", error);
		return;
	}

	control_lvb_read(ls, &lvb_gen, ls->ls_lvb_bits);

	spin_lock(&ls->ls_recover_spin);
	if (block_gen != ls->ls_recover_block ||
	    start_gen != ls->ls_recover_start) {
		fs_info(sdp, "recover generation %u block1 %u %u\n",
			start_gen, block_gen, ls->ls_recover_block);
		spin_unlock(&ls->ls_recover_spin);
		control_lock(sdp, DLM_LOCK_NL, DLM_LKF_CONVERT);
		return;
	}

	recover_size = ls->ls_recover_size;

	if (lvb_gen <= start_gen) {
		/*
		 * Clear lvb bits for jids we've successfully recovered.
		 * Because all nodes attempt to recover failed journals,
		 * a journal can be recovered multiple times successfully
		 * in succession.  Only the first will really do recovery,
		 * the others find it clean, but still report a successful
		 * recovery.  So, another node may have already recovered
		 * the jid and cleared the lvb bit for it.
		 */
		for (i = 0; i < recover_size; i++) {
			if (ls->ls_recover_result[i] != LM_RD_SUCCESS)
				continue;

			ls->ls_recover_result[i] = 0;

			if (!test_bit_le(i, ls->ls_lvb_bits + JID_BITMAP_OFFSET))
				continue;

			__clear_bit_le(i, ls->ls_lvb_bits + JID_BITMAP_OFFSET);
			write_lvb = 1;
		}
	}

	if (lvb_gen == start_gen) {
		/*
		 * Failed slots before start_gen are already set in lvb.
		 */
		for (i = 0; i < recover_size; i++) {
			if (!ls->ls_recover_submit[i])
				continue;
			if (ls->ls_recover_submit[i] < lvb_gen)
				ls->ls_recover_submit[i] = 0;
		}
	} else if (lvb_gen < start_gen) {
		/*
		 * Failed slots before start_gen are not yet set in lvb.
		 */
		for (i = 0; i < recover_size; i++) {
			if (!ls->ls_recover_submit[i])
				continue;
			if (ls->ls_recover_submit[i] < start_gen) {
				ls->ls_recover_submit[i] = 0;
				__set_bit_le(i, ls->ls_lvb_bits + JID_BITMAP_OFFSET);
			}
		}
		/* even if there are no bits to set, we need to write the
		   latest generation to the lvb */
		write_lvb = 1;
	} else {
		/*
		 * we should be getting a recover_done() for lvb_gen soon
		 */
	}
	spin_unlock(&ls->ls_recover_spin);

	if (write_lvb) {
		control_lvb_write(ls, start_gen, ls->ls_lvb_bits);
		flags = DLM_LKF_CONVERT | DLM_LKF_VALBLK;
	} else {
		flags = DLM_LKF_CONVERT;
	}

	error = control_lock(sdp, DLM_LOCK_NL, flags);
	if (error) {
		fs_err(sdp, "control lock NL error %d\n", error);
		return;
	}

	/*
	 * Everyone will see jid bits set in the lvb, run gfs2_recover_set(),
	 * and clear a jid bit in the lvb if the recovery is a success.
	 * Eventually all journals will be recovered, all jid bits will
	 * be cleared in the lvb, and everyone will clear BLOCK_LOCKS.
	 */

	for (i = 0; i < recover_size; i++) {
		if (test_bit_le(i, ls->ls_lvb_bits + JID_BITMAP_OFFSET)) {
			fs_info(sdp, "recover generation %u jid %d\n",
				start_gen, i);
			gfs2_recover_set(sdp, i);
			recover_set++;
		}
	}
	if (recover_set)
		return;

	/*
	 * No more jid bits set in lvb, all recovery is done, unblock locks
	 * (unless a new recover_prep callback has occured blocking locks
	 * again while working above)
	 */

	spin_lock(&ls->ls_recover_spin);
	if (ls->ls_recover_block == block_gen &&
	    ls->ls_recover_start == start_gen) {
		clear_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags);
		spin_unlock(&ls->ls_recover_spin);
		fs_info(sdp, "recover generation %u done\n", start_gen);
		gfs2_glock_thaw(sdp);
	} else {
		fs_info(sdp, "recover generation %u block2 %u %u\n",
			start_gen, block_gen, ls->ls_recover_block);
		spin_unlock(&ls->ls_recover_spin);
	}
}

static int control_mount(struct gfs2_sbd *sdp)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	uint32_t start_gen, block_gen, mount_gen, lvb_gen;
	int mounted_mode;
	int retries = 0;
	int error;

	memset(&ls->ls_mounted_lksb, 0, sizeof(struct dlm_lksb));
	memset(&ls->ls_control_lksb, 0, sizeof(struct dlm_lksb));
	memset(&ls->ls_control_lvb, 0, GDLM_LVB_SIZE);
	ls->ls_control_lksb.sb_lvbptr = ls->ls_control_lvb;
	init_completion(&ls->ls_sync_wait);

	set_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags);

	error = control_lock(sdp, DLM_LOCK_NL, DLM_LKF_VALBLK);
	if (error) {
		fs_err(sdp, "control_mount control_lock NL error %d\n", error);
		return error;
	}

	error = mounted_lock(sdp, DLM_LOCK_NL, 0);
	if (error) {
		fs_err(sdp, "control_mount mounted_lock NL error %d\n", error);
		control_unlock(sdp);
		return error;
	}
	mounted_mode = DLM_LOCK_NL;

restart:
	if (retries++ && signal_pending(current)) {
		error = -EINTR;
		goto fail;
	}

	/*
	 * We always start with both locks in NL. control_lock is
	 * demoted to NL below so we don't need to do it here.
	 */

	if (mounted_mode != DLM_LOCK_NL) {
		error = mounted_lock(sdp, DLM_LOCK_NL, DLM_LKF_CONVERT);
		if (error)
			goto fail;
		mounted_mode = DLM_LOCK_NL;
	}

	/*
	 * Other nodes need to do some work in dlm recovery and gfs2_control
	 * before the recover_done and control_lock will be ready for us below.
	 * A delay here is not required but often avoids having to retry.
	 */

	msleep_interruptible(500);

	/*
	 * Acquire control_lock in EX and mounted_lock in either EX or PR.
	 * control_lock lvb keeps track of any pending journal recoveries.
	 * mounted_lock indicates if any other nodes have the fs mounted.
	 */

	error = control_lock(sdp, DLM_LOCK_EX, DLM_LKF_CONVERT|DLM_LKF_NOQUEUE|DLM_LKF_VALBLK);
	if (error == -EAGAIN) {
		goto restart;
	} else if (error) {
		fs_err(sdp, "control_mount control_lock EX error %d\n", error);
		goto fail;
	}

	/**
	 * If we're a spectator, we don't want to take the lock in EX because
	 * we cannot do the first-mount responsibility it implies: recovery.
	 */
	if (sdp->sd_args.ar_spectator)
		goto locks_done;

	error = mounted_lock(sdp, DLM_LOCK_EX, DLM_LKF_CONVERT|DLM_LKF_NOQUEUE);
	if (!error) {
		mounted_mode = DLM_LOCK_EX;
		goto locks_done;
	} else if (error != -EAGAIN) {
		fs_err(sdp, "control_mount mounted_lock EX error %d\n", error);
		goto fail;
	}

	error = mounted_lock(sdp, DLM_LOCK_PR, DLM_LKF_CONVERT|DLM_LKF_NOQUEUE);
	if (!error) {
		mounted_mode = DLM_LOCK_PR;
		goto locks_done;
	} else {
		/* not even -EAGAIN should happen here */
		fs_err(sdp, "control_mount mounted_lock PR error %d\n", error);
		goto fail;
	}

locks_done:
	/*
	 * If we got both locks above in EX, then we're the first mounter.
	 * If not, then we need to wait for the control_lock lvb to be
	 * updated by other mounted nodes to reflect our mount generation.
	 *
	 * In simple first mounter cases, first mounter will see zero lvb_gen,
	 * but in cases where all existing nodes leave/fail before mounting
	 * nodes finish control_mount, then all nodes will be mounting and
	 * lvb_gen will be non-zero.
	 */

	control_lvb_read(ls, &lvb_gen, ls->ls_lvb_bits);

	if (lvb_gen == 0xFFFFFFFF) {
		/* special value to force mount attempts to fail */
		fs_err(sdp, "control_mount control_lock disabled\n");
		error = -EINVAL;
		goto fail;
	}

	if (mounted_mode == DLM_LOCK_EX) {
		/* first mounter, keep both EX while doing first recovery */
		spin_lock(&ls->ls_recover_spin);
		clear_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags);
		set_bit(DFL_MOUNT_DONE, &ls->ls_recover_flags);
		set_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags);
		spin_unlock(&ls->ls_recover_spin);
		fs_info(sdp, "first mounter control generation %u\n", lvb_gen);
		return 0;
	}

	error = control_lock(sdp, DLM_LOCK_NL, DLM_LKF_CONVERT);
	if (error)
		goto fail;

	/*
	 * We are not first mounter, now we need to wait for the control_lock
	 * lvb generation to be >= the generation from our first recover_done
	 * and all lvb bits to be clear (no pending journal recoveries.)
	 */

	if (!all_jid_bits_clear(ls->ls_lvb_bits)) {
		/* journals need recovery, wait until all are clear */
		fs_info(sdp, "control_mount wait for journal recovery\n");
		goto restart;
	}

	spin_lock(&ls->ls_recover_spin);
	block_gen = ls->ls_recover_block;
	start_gen = ls->ls_recover_start;
	mount_gen = ls->ls_recover_mount;

	if (lvb_gen < mount_gen) {
		/* wait for mounted nodes to update control_lock lvb to our
		   generation, which might include new recovery bits set */
		if (sdp->sd_args.ar_spectator) {
			fs_info(sdp, "Recovery is required. Waiting for a "
				"non-spectator to mount.\n");
			msleep_interruptible(1000);
		} else {
			fs_info(sdp, "control_mount wait1 block %u start %u "
				"mount %u lvb %u flags %lx\n", block_gen,
				start_gen, mount_gen, lvb_gen,
				ls->ls_recover_flags);
		}
		spin_unlock(&ls->ls_recover_spin);
		goto restart;
	}

	if (lvb_gen != start_gen) {
		/* wait for mounted nodes to update control_lock lvb to the
		   latest recovery generation */
		fs_info(sdp, "control_mount wait2 block %u start %u mount %u "
			"lvb %u flags %lx\n", block_gen, start_gen, mount_gen,
			lvb_gen, ls->ls_recover_flags);
		spin_unlock(&ls->ls_recover_spin);
		goto restart;
	}

	if (block_gen == start_gen) {
		/* dlm recovery in progress, wait for it to finish */
		fs_info(sdp, "control_mount wait3 block %u start %u mount %u "
			"lvb %u flags %lx\n", block_gen, start_gen, mount_gen,
			lvb_gen, ls->ls_recover_flags);
		spin_unlock(&ls->ls_recover_spin);
		goto restart;
	}

	clear_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags);
	set_bit(DFL_MOUNT_DONE, &ls->ls_recover_flags);
	memset(ls->ls_recover_submit, 0, ls->ls_recover_size*sizeof(uint32_t));
	memset(ls->ls_recover_result, 0, ls->ls_recover_size*sizeof(uint32_t));
	spin_unlock(&ls->ls_recover_spin);
	return 0;

fail:
	mounted_unlock(sdp);
	control_unlock(sdp);
	return error;
}

static int control_first_done(struct gfs2_sbd *sdp)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	uint32_t start_gen, block_gen;
	int error;

restart:
	spin_lock(&ls->ls_recover_spin);
	start_gen = ls->ls_recover_start;
	block_gen = ls->ls_recover_block;

	if (test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags) ||
	    !test_bit(DFL_MOUNT_DONE, &ls->ls_recover_flags) ||
	    !test_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags)) {
		/* sanity check, should not happen */
		fs_err(sdp, "control_first_done start %u block %u flags %lx\n",
		       start_gen, block_gen, ls->ls_recover_flags);
		spin_unlock(&ls->ls_recover_spin);
		control_unlock(sdp);
		return -1;
	}

	if (start_gen == block_gen) {
		/*
		 * Wait for the end of a dlm recovery cycle to switch from
		 * first mounter recovery.  We can ignore any recover_slot
		 * callbacks between the recover_prep and next recover_done
		 * because we are still the first mounter and any failed nodes
		 * have not fully mounted, so they don't need recovery.
		 */
		spin_unlock(&ls->ls_recover_spin);
		fs_info(sdp, "control_first_done wait gen %u\n", start_gen);

		wait_on_bit(&ls->ls_recover_flags, DFL_DLM_RECOVERY,
			    TASK_UNINTERRUPTIBLE);
		goto restart;
	}

	clear_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags);
	set_bit(DFL_FIRST_MOUNT_DONE, &ls->ls_recover_flags);
	memset(ls->ls_recover_submit, 0, ls->ls_recover_size*sizeof(uint32_t));
	memset(ls->ls_recover_result, 0, ls->ls_recover_size*sizeof(uint32_t));
	spin_unlock(&ls->ls_recover_spin);

	memset(ls->ls_lvb_bits, 0, GDLM_LVB_SIZE);
	control_lvb_write(ls, start_gen, ls->ls_lvb_bits);

	error = mounted_lock(sdp, DLM_LOCK_PR, DLM_LKF_CONVERT);
	if (error)
		fs_err(sdp, "control_first_done mounted PR error %d\n", error);

	error = control_lock(sdp, DLM_LOCK_NL, DLM_LKF_CONVERT|DLM_LKF_VALBLK);
	if (error)
		fs_err(sdp, "control_first_done control NL error %d\n", error);

	return error;
}

/*
 * Expand static jid arrays if necessary (by increments of RECOVER_SIZE_INC)
 * to accomodate the largest slot number.  (NB dlm slot numbers start at 1,
 * gfs2 jids start at 0, so jid = slot - 1)
 */

#define RECOVER_SIZE_INC 16

static int set_recover_size(struct gfs2_sbd *sdp, struct dlm_slot *slots,
			    int num_slots)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	uint32_t *submit = NULL;
	uint32_t *result = NULL;
	uint32_t old_size, new_size;
	int i, max_jid;

	if (!ls->ls_lvb_bits) {
		ls->ls_lvb_bits = kzalloc(GDLM_LVB_SIZE, GFP_NOFS);
		if (!ls->ls_lvb_bits)
			return -ENOMEM;
	}

	max_jid = 0;
	for (i = 0; i < num_slots; i++) {
		if (max_jid < slots[i].slot - 1)
			max_jid = slots[i].slot - 1;
	}

	old_size = ls->ls_recover_size;

	if (old_size >= max_jid + 1)
		return 0;

	new_size = old_size + RECOVER_SIZE_INC;

	submit = kcalloc(new_size, sizeof(uint32_t), GFP_NOFS);
	result = kcalloc(new_size, sizeof(uint32_t), GFP_NOFS);
	if (!submit || !result) {
		kfree(submit);
		kfree(result);
		return -ENOMEM;
	}

	spin_lock(&ls->ls_recover_spin);
	memcpy(submit, ls->ls_recover_submit, old_size * sizeof(uint32_t));
	memcpy(result, ls->ls_recover_result, old_size * sizeof(uint32_t));
	kfree(ls->ls_recover_submit);
	kfree(ls->ls_recover_result);
	ls->ls_recover_submit = submit;
	ls->ls_recover_result = result;
	ls->ls_recover_size = new_size;
	spin_unlock(&ls->ls_recover_spin);
	return 0;
}

static void free_recover_size(struct lm_lockstruct *ls)
{
	kfree(ls->ls_lvb_bits);
	kfree(ls->ls_recover_submit);
	kfree(ls->ls_recover_result);
	ls->ls_recover_submit = NULL;
	ls->ls_recover_result = NULL;
	ls->ls_recover_size = 0;
	ls->ls_lvb_bits = NULL;
}

/* dlm calls before it does lock recovery */

static void gdlm_recover_prep(void *arg)
{
	struct gfs2_sbd *sdp = arg;
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;

	spin_lock(&ls->ls_recover_spin);
	ls->ls_recover_block = ls->ls_recover_start;
	set_bit(DFL_DLM_RECOVERY, &ls->ls_recover_flags);

	if (!test_bit(DFL_MOUNT_DONE, &ls->ls_recover_flags) ||
	     test_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags)) {
		spin_unlock(&ls->ls_recover_spin);
		return;
	}
	set_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags);
	spin_unlock(&ls->ls_recover_spin);
}

/* dlm calls after recover_prep has been completed on all lockspace members;
   identifies slot/jid of failed member */

static void gdlm_recover_slot(void *arg, struct dlm_slot *slot)
{
	struct gfs2_sbd *sdp = arg;
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	int jid = slot->slot - 1;

	spin_lock(&ls->ls_recover_spin);
	if (ls->ls_recover_size < jid + 1) {
		fs_err(sdp, "recover_slot jid %d gen %u short size %d\n",
		       jid, ls->ls_recover_block, ls->ls_recover_size);
		spin_unlock(&ls->ls_recover_spin);
		return;
	}

	if (ls->ls_recover_submit[jid]) {
		fs_info(sdp, "recover_slot jid %d gen %u prev %u\n",
			jid, ls->ls_recover_block, ls->ls_recover_submit[jid]);
	}
	ls->ls_recover_submit[jid] = ls->ls_recover_block;
	spin_unlock(&ls->ls_recover_spin);
}

/* dlm calls after recover_slot and after it completes lock recovery */

static void gdlm_recover_done(void *arg, struct dlm_slot *slots, int num_slots,
			      int our_slot, uint32_t generation)
{
	struct gfs2_sbd *sdp = arg;
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;

	/* ensure the ls jid arrays are large enough */
	set_recover_size(sdp, slots, num_slots);

	spin_lock(&ls->ls_recover_spin);
	ls->ls_recover_start = generation;

	if (!ls->ls_recover_mount) {
		ls->ls_recover_mount = generation;
		ls->ls_jid = our_slot - 1;
	}

	if (!test_bit(DFL_UNMOUNT, &ls->ls_recover_flags))
		queue_delayed_work(gfs2_control_wq, &sdp->sd_control_work, 0);

	clear_bit(DFL_DLM_RECOVERY, &ls->ls_recover_flags);
	smp_mb__after_atomic();
	wake_up_bit(&ls->ls_recover_flags, DFL_DLM_RECOVERY);
	spin_unlock(&ls->ls_recover_spin);
}

/* gfs2_recover thread has a journal recovery result */

static void gdlm_recovery_result(struct gfs2_sbd *sdp, unsigned int jid,
				 unsigned int result)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;

	if (test_bit(DFL_NO_DLM_OPS, &ls->ls_recover_flags))
		return;

	/* don't care about the recovery of own journal during mount */
	if (jid == ls->ls_jid)
		return;

	spin_lock(&ls->ls_recover_spin);
	if (test_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags)) {
		spin_unlock(&ls->ls_recover_spin);
		return;
	}
	if (ls->ls_recover_size < jid + 1) {
		fs_err(sdp, "recovery_result jid %d short size %d\n",
		       jid, ls->ls_recover_size);
		spin_unlock(&ls->ls_recover_spin);
		return;
	}

	fs_info(sdp, "recover jid %d result %s\n", jid,
		result == LM_RD_GAVEUP ? "busy" : "success");

	ls->ls_recover_result[jid] = result;

	/* GAVEUP means another node is recovering the journal; delay our
	   next attempt to recover it, to give the other node a chance to
	   finish before trying again */

	if (!test_bit(DFL_UNMOUNT, &ls->ls_recover_flags))
		queue_delayed_work(gfs2_control_wq, &sdp->sd_control_work,
				   result == LM_RD_GAVEUP ? HZ : 0);
	spin_unlock(&ls->ls_recover_spin);
}

static const struct dlm_lockspace_ops gdlm_lockspace_ops = {
	.recover_prep = gdlm_recover_prep,
	.recover_slot = gdlm_recover_slot,
	.recover_done = gdlm_recover_done,
};

static int gdlm_mount(struct gfs2_sbd *sdp, const char *table)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	char cluster[GFS2_LOCKNAME_LEN];
	const char *fsname;
	uint32_t flags;
	int error, ops_result;

	/*
	 * initialize everything
	 */

	INIT_DELAYED_WORK(&sdp->sd_control_work, gfs2_control_func);
	spin_lock_init(&ls->ls_recover_spin);
	ls->ls_recover_flags = 0;
	ls->ls_recover_mount = 0;
	ls->ls_recover_start = 0;
	ls->ls_recover_block = 0;
	ls->ls_recover_size = 0;
	ls->ls_recover_submit = NULL;
	ls->ls_recover_result = NULL;
	ls->ls_lvb_bits = NULL;

	error = set_recover_size(sdp, NULL, 0);
	if (error)
		goto fail;

	/*
	 * prepare dlm_new_lockspace args
	 */

	fsname = strchr(table, ':');
	if (!fsname) {
		fs_info(sdp, "no fsname found\n");
		error = -EINVAL;
		goto fail_free;
	}
	memset(cluster, 0, sizeof(cluster));
	memcpy(cluster, table, strlen(table) - strlen(fsname));
	fsname++;

	flags = DLM_LSFL_FS | DLM_LSFL_NEWEXCL;

	/*
	 * create/join lockspace
	 */

	error = dlm_new_lockspace(fsname, cluster, flags, GDLM_LVB_SIZE,
				  &gdlm_lockspace_ops, sdp, &ops_result,
				  &ls->ls_dlm);
	if (error) {
		fs_err(sdp, "dlm_new_lockspace error %d\n", error);
		goto fail_free;
	}

	if (ops_result < 0) {
		/*
		 * dlm does not support ops callbacks,
		 * old dlm_controld/gfs_controld are used, try without ops.
		 */
		fs_info(sdp, "dlm lockspace ops not used\n");
		free_recover_size(ls);
		set_bit(DFL_NO_DLM_OPS, &ls->ls_recover_flags);
		return 0;
	}

	if (!test_bit(SDF_NOJOURNALID, &sdp->sd_flags)) {
		fs_err(sdp, "dlm lockspace ops disallow jid preset\n");
		error = -EINVAL;
		goto fail_release;
	}

	/*
	 * control_mount() uses control_lock to determine first mounter,
	 * and for later mounts, waits for any recoveries to be cleared.
	 */

	error = control_mount(sdp);
	if (error) {
		fs_err(sdp, "mount control error %d\n", error);
		goto fail_release;
	}

	ls->ls_first = !!test_bit(DFL_FIRST_MOUNT, &ls->ls_recover_flags);
	clear_bit(SDF_NOJOURNALID, &sdp->sd_flags);
	smp_mb__after_atomic();
	wake_up_bit(&sdp->sd_flags, SDF_NOJOURNALID);
	return 0;

fail_release:
	dlm_release_lockspace(ls->ls_dlm, 2);
fail_free:
	free_recover_size(ls);
fail:
	return error;
}

static void gdlm_first_done(struct gfs2_sbd *sdp)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;
	int error;

	if (test_bit(DFL_NO_DLM_OPS, &ls->ls_recover_flags))
		return;

	error = control_first_done(sdp);
	if (error)
		fs_err(sdp, "mount first_done error %d\n", error);
}

static void gdlm_unmount(struct gfs2_sbd *sdp)
{
	struct lm_lockstruct *ls = &sdp->sd_lockstruct;

	if (test_bit(DFL_NO_DLM_OPS, &ls->ls_recover_flags))
		goto release;

	/* wait for gfs2_control_wq to be done with this mount */

	spin_lock(&ls->ls_recover_spin);
	set_bit(DFL_UNMOUNT, &ls->ls_recover_flags);
	spin_unlock(&ls->ls_recover_spin);
	flush_delayed_work(&sdp->sd_control_work);

	/* mounted_lock and control_lock will be purged in dlm recovery */
release:
	if (ls->ls_dlm) {
		dlm_release_lockspace(ls->ls_dlm, 2);
		ls->ls_dlm = NULL;
	}

	free_recover_size(ls);
}

static const match_table_t dlm_tokens = {
	{ Opt_jid, "jid=%d"},
	{ Opt_id, "id=%d"},
	{ Opt_first, "first=%d"},
	{ Opt_nodir, "nodir=%d"},
	{ Opt_err, NULL },
};

const struct lm_lockops gfs2_dlm_ops = {
	.lm_proto_name = "lock_dlm",
	.lm_mount = gdlm_mount,
	.lm_first_done = gdlm_first_done,
	.lm_recovery_result = gdlm_recovery_result,
	.lm_unmount = gdlm_unmount,
	.lm_put_lock = gdlm_put_lock,
	.lm_lock = gdlm_lock,
	.lm_cancel = gdlm_cancel,
	.lm_tokens = &dlm_tokens,
};