summaryrefslogtreecommitdiffstats
path: root/drivers/nvdimm/btt.c
blob: b6ba0618ea46736fefb053bc067adb1e4f7d726f (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
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
/*
 * Block Translation Table
 * Copyright (c) 2014-2015, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.
 */
#include <linux/highmem.h>
#include <linux/debugfs.h>
#include <linux/blkdev.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/hdreg.h>
#include <linux/genhd.h>
#include <linux/sizes.h>
#include <linux/ndctl.h>
#include <linux/fs.h>
#include <linux/nd.h>
#include "btt.h"
#include "nd.h"

enum log_ent_request {
	LOG_NEW_ENT = 0,
	LOG_OLD_ENT
};

static int arena_read_bytes(struct arena_info *arena, resource_size_t offset,
		void *buf, size_t n, unsigned long flags)
{
	struct nd_btt *nd_btt = arena->nd_btt;
	struct nd_namespace_common *ndns = nd_btt->ndns;

	/* arena offsets are 4K from the base of the device */
	offset += SZ_4K;
	return nvdimm_read_bytes(ndns, offset, buf, n, flags);
}

static int arena_write_bytes(struct arena_info *arena, resource_size_t offset,
		void *buf, size_t n, unsigned long flags)
{
	struct nd_btt *nd_btt = arena->nd_btt;
	struct nd_namespace_common *ndns = nd_btt->ndns;

	/* arena offsets are 4K from the base of the device */
	offset += SZ_4K;
	return nvdimm_write_bytes(ndns, offset, buf, n, flags);
}

static int btt_info_write(struct arena_info *arena, struct btt_sb *super)
{
	int ret;

	/*
	 * infooff and info2off should always be at least 512B aligned.
	 * We rely on that to make sure rw_bytes does error clearing
	 * correctly, so make sure that is the case.
	 */
	WARN_ON_ONCE(!IS_ALIGNED(arena->infooff, 512));
	WARN_ON_ONCE(!IS_ALIGNED(arena->info2off, 512));

	ret = arena_write_bytes(arena, arena->info2off, super,
			sizeof(struct btt_sb), 0);
	if (ret)
		return ret;

	return arena_write_bytes(arena, arena->infooff, super,
			sizeof(struct btt_sb), 0);
}

static int btt_info_read(struct arena_info *arena, struct btt_sb *super)
{
	WARN_ON(!super);
	return arena_read_bytes(arena, arena->infooff, super,
			sizeof(struct btt_sb), 0);
}

/*
 * 'raw' version of btt_map write
 * Assumptions:
 *   mapping is in little-endian
 *   mapping contains 'E' and 'Z' flags as desired
 */
static int __btt_map_write(struct arena_info *arena, u32 lba, __le32 mapping,
		unsigned long flags)
{
	u64 ns_off = arena->mapoff + (lba * MAP_ENT_SIZE);

	WARN_ON(lba >= arena->external_nlba);
	return arena_write_bytes(arena, ns_off, &mapping, MAP_ENT_SIZE, flags);
}

static int btt_map_write(struct arena_info *arena, u32 lba, u32 mapping,
			u32 z_flag, u32 e_flag, unsigned long rwb_flags)
{
	u32 ze;
	__le32 mapping_le;

	/*
	 * This 'mapping' is supposed to be just the LBA mapping, without
	 * any flags set, so strip the flag bits.
	 */
	mapping &= MAP_LBA_MASK;

	ze = (z_flag << 1) + e_flag;
	switch (ze) {
	case 0:
		/*
		 * We want to set neither of the Z or E flags, and
		 * in the actual layout, this means setting the bit
		 * positions of both to '1' to indicate a 'normal'
		 * map entry
		 */
		mapping |= MAP_ENT_NORMAL;
		break;
	case 1:
		mapping |= (1 << MAP_ERR_SHIFT);
		break;
	case 2:
		mapping |= (1 << MAP_TRIM_SHIFT);
		break;
	default:
		/*
		 * The case where Z and E are both sent in as '1' could be
		 * construed as a valid 'normal' case, but we decide not to,
		 * to avoid confusion
		 */
		WARN_ONCE(1, "Invalid use of Z and E flags\n");
		return -EIO;
	}

	mapping_le = cpu_to_le32(mapping);
	return __btt_map_write(arena, lba, mapping_le, rwb_flags);
}

static int btt_map_read(struct arena_info *arena, u32 lba, u32 *mapping,
			int *trim, int *error, unsigned long rwb_flags)
{
	int ret;
	__le32 in;
	u32 raw_mapping, postmap, ze, z_flag, e_flag;
	u64 ns_off = arena->mapoff + (lba * MAP_ENT_SIZE);

	WARN_ON(lba >= arena->external_nlba);

	ret = arena_read_bytes(arena, ns_off, &in, MAP_ENT_SIZE, rwb_flags);
	if (ret)
		return ret;

	raw_mapping = le32_to_cpu(in);

	z_flag = (raw_mapping & MAP_TRIM_MASK) >> MAP_TRIM_SHIFT;
	e_flag = (raw_mapping & MAP_ERR_MASK) >> MAP_ERR_SHIFT;
	ze = (z_flag << 1) + e_flag;
	postmap = raw_mapping & MAP_LBA_MASK;

	/* Reuse the {z,e}_flag variables for *trim and *error */
	z_flag = 0;
	e_flag = 0;

	switch (ze) {
	case 0:
		/* Initial state. Return postmap = premap */
		*mapping = lba;
		break;
	case 1:
		*mapping = postmap;
		e_flag = 1;
		break;
	case 2:
		*mapping = postmap;
		z_flag = 1;
		break;
	case 3:
		*mapping = postmap;
		break;
	default:
		return -EIO;
	}

	if (trim)
		*trim = z_flag;
	if (error)
		*error = e_flag;

	return ret;
}

static int btt_log_read_pair(struct arena_info *arena, u32 lane,
			struct log_entry *ent)
{
	WARN_ON(!ent);
	return arena_read_bytes(arena,
			arena->logoff + (2 * lane * LOG_ENT_SIZE), ent,
			2 * LOG_ENT_SIZE, 0);
}

static struct dentry *debugfs_root;

static void arena_debugfs_init(struct arena_info *a, struct dentry *parent,
				int idx)
{
	char dirname[32];
	struct dentry *d;

	/* If for some reason, parent bttN was not created, exit */
	if (!parent)
		return;

	snprintf(dirname, 32, "arena%d", idx);
	d = debugfs_create_dir(dirname, parent);
	if (IS_ERR_OR_NULL(d))
		return;
	a->debugfs_dir = d;

	debugfs_create_x64("size", S_IRUGO, d, &a->size);
	debugfs_create_x64("external_lba_start", S_IRUGO, d,
				&a->external_lba_start);
	debugfs_create_x32("internal_nlba", S_IRUGO, d, &a->internal_nlba);
	debugfs_create_u32("internal_lbasize", S_IRUGO, d,
				&a->internal_lbasize);
	debugfs_create_x32("external_nlba", S_IRUGO, d, &a->external_nlba);
	debugfs_create_u32("external_lbasize", S_IRUGO, d,
				&a->external_lbasize);
	debugfs_create_u32("nfree", S_IRUGO, d, &a->nfree);
	debugfs_create_u16("version_major", S_IRUGO, d, &a->version_major);
	debugfs_create_u16("version_minor", S_IRUGO, d, &a->version_minor);
	debugfs_create_x64("nextoff", S_IRUGO, d, &a->nextoff);
	debugfs_create_x64("infooff", S_IRUGO, d, &a->infooff);
	debugfs_create_x64("dataoff", S_IRUGO, d, &a->dataoff);
	debugfs_create_x64("mapoff", S_IRUGO, d, &a->mapoff);
	debugfs_create_x64("logoff", S_IRUGO, d, &a->logoff);
	debugfs_create_x64("info2off", S_IRUGO, d, &a->info2off);
	debugfs_create_x32("flags", S_IRUGO, d, &a->flags);
}

static void btt_debugfs_init(struct btt *btt)
{
	int i = 0;
	struct arena_info *arena;

	btt->debugfs_dir = debugfs_create_dir(dev_name(&btt->nd_btt->dev),
						debugfs_root);
	if (IS_ERR_OR_NULL(btt->debugfs_dir))
		return;

	list_for_each_entry(arena, &btt->arena_list, list) {
		arena_debugfs_init(arena, btt->debugfs_dir, i);
		i++;
	}
}

/*
 * This function accepts two log entries, and uses the
 * sequence number to find the 'older' entry.
 * It also updates the sequence number in this old entry to
 * make it the 'new' one if the mark_flag is set.
 * Finally, it returns which of the entries was the older one.
 *
 * TODO The logic feels a bit kludge-y. make it better..
 */
static int btt_log_get_old(struct log_entry *ent)
{
	int old;

	/*
	 * the first ever time this is seen, the entry goes into [0]
	 * the next time, the following logic works out to put this
	 * (next) entry into [1]
	 */
	if (ent[0].seq == 0) {
		ent[0].seq = cpu_to_le32(1);
		return 0;
	}

	if (ent[0].seq == ent[1].seq)
		return -EINVAL;
	if (le32_to_cpu(ent[0].seq) + le32_to_cpu(ent[1].seq) > 5)
		return -EINVAL;

	if (le32_to_cpu(ent[0].seq) < le32_to_cpu(ent[1].seq)) {
		if (le32_to_cpu(ent[1].seq) - le32_to_cpu(ent[0].seq) == 1)
			old = 0;
		else
			old = 1;
	} else {
		if (le32_to_cpu(ent[0].seq) - le32_to_cpu(ent[1].seq) == 1)
			old = 1;
		else
			old = 0;
	}

	return old;
}

static struct device *to_dev(struct arena_info *arena)
{
	return &arena->nd_btt->dev;
}

/*
 * This function copies the desired (old/new) log entry into ent if
 * it is not NULL. It returns the sub-slot number (0 or 1)
 * where the desired log entry was found. Negative return values
 * indicate errors.
 */
static int btt_log_read(struct arena_info *arena, u32 lane,
			struct log_entry *ent, int old_flag)
{
	int ret;
	int old_ent, ret_ent;
	struct log_entry log[2];

	ret = btt_log_read_pair(arena, lane, log);
	if (ret)
		return -EIO;

	old_ent = btt_log_get_old(log);
	if (old_ent < 0 || old_ent > 1) {
		dev_info(to_dev(arena),
				"log corruption (%d): lane %d seq [%d, %d]\n",
			old_ent, lane, log[0].seq, log[1].seq);
		/* TODO set error state? */
		return -EIO;
	}

	ret_ent = (old_flag ? old_ent : (1 - old_ent));

	if (ent != NULL)
		memcpy(ent, &log[ret_ent], LOG_ENT_SIZE);

	return ret_ent;
}

/*
 * This function commits a log entry to media
 * It does _not_ prepare the freelist entry for the next write
 * btt_flog_write is the wrapper for updating the freelist elements
 */
static int __btt_log_write(struct arena_info *arena, u32 lane,
			u32 sub, struct log_entry *ent, unsigned long flags)
{
	int ret;
	/*
	 * Ignore the padding in log_entry for calculating log_half.
	 * The entry is 'committed' when we write the sequence number,
	 * and we want to ensure that that is the last thing written.
	 * We don't bother writing the padding as that would be extra
	 * media wear and write amplification
	 */
	unsigned int log_half = (LOG_ENT_SIZE - 2 * sizeof(u64)) / 2;
	u64 ns_off = arena->logoff + (((2 * lane) + sub) * LOG_ENT_SIZE);
	void *src = ent;

	/* split the 16B write into atomic, durable halves */
	ret = arena_write_bytes(arena, ns_off, src, log_half, flags);
	if (ret)
		return ret;

	ns_off += log_half;
	src += log_half;
	return arena_write_bytes(arena, ns_off, src, log_half, flags);
}

static int btt_flog_write(struct arena_info *arena, u32 lane, u32 sub,
			struct log_entry *ent)
{
	int ret;

	ret = __btt_log_write(arena, lane, sub, ent, NVDIMM_IO_ATOMIC);
	if (ret)
		return ret;

	/* prepare the next free entry */
	arena->freelist[lane].sub = 1 - arena->freelist[lane].sub;
	if (++(arena->freelist[lane].seq) == 4)
		arena->freelist[lane].seq = 1;
	arena->freelist[lane].block = le32_to_cpu(ent->old_map);

	return ret;
}

/*
 * This function initializes the BTT map to the initial state, which is
 * all-zeroes, and indicates an identity mapping
 */
static int btt_map_init(struct arena_info *arena)
{
	int ret = -EINVAL;
	void *zerobuf;
	size_t offset = 0;
	size_t chunk_size = SZ_2M;
	size_t mapsize = arena->logoff - arena->mapoff;

	zerobuf = kzalloc(chunk_size, GFP_KERNEL);
	if (!zerobuf)
		return -ENOMEM;

	/*
	 * mapoff should always be at least 512B  aligned. We rely on that to
	 * make sure rw_bytes does error clearing correctly, so make sure that
	 * is the case.
	 */
	WARN_ON_ONCE(!IS_ALIGNED(arena->mapoff, 512));

	while (mapsize) {
		size_t size = min(mapsize, chunk_size);

		WARN_ON_ONCE(size < 512);
		ret = arena_write_bytes(arena, arena->mapoff + offset, zerobuf,
				size, 0);
		if (ret)
			goto free;

		offset += size;
		mapsize -= size;
		cond_resched();
	}

 free:
	kfree(zerobuf);
	return ret;
}

/*
 * This function initializes the BTT log with 'fake' entries pointing
 * to the initial reserved set of blocks as being free
 */
static int btt_log_init(struct arena_info *arena)
{
	size_t logsize = arena->info2off - arena->logoff;
	size_t chunk_size = SZ_4K, offset = 0;
	struct log_entry log;
	void *zerobuf;
	int ret;
	u32 i;

	zerobuf = kzalloc(chunk_size, GFP_KERNEL);
	if (!zerobuf)
		return -ENOMEM;
	/*
	 * logoff should always be at least 512B  aligned. We rely on that to
	 * make sure rw_bytes does error clearing correctly, so make sure that
	 * is the case.
	 */
	WARN_ON_ONCE(!IS_ALIGNED(arena->logoff, 512));

	while (logsize) {
		size_t size = min(logsize, chunk_size);

		WARN_ON_ONCE(size < 512);
		ret = arena_write_bytes(arena, arena->logoff + offset, zerobuf,
				size, 0);
		if (ret)
			goto free;

		offset += size;
		logsize -= size;
		cond_resched();
	}

	for (i = 0; i < arena->nfree; i++) {
		log.lba = cpu_to_le32(i);
		log.old_map = cpu_to_le32(arena->external_nlba + i);
		log.new_map = cpu_to_le32(arena->external_nlba + i);
		log.seq = cpu_to_le32(LOG_SEQ_INIT);
		ret = __btt_log_write(arena, i, 0, &log, 0);
		if (ret)
			goto free;
	}

 free:
	kfree(zerobuf);
	return ret;
}

static int btt_freelist_init(struct arena_info *arena)
{
	int old, new, ret;
	u32 i, map_entry;
	struct log_entry log_new, log_old;

	arena->freelist = kcalloc(arena->nfree, sizeof(struct free_entry),
					GFP_KERNEL);
	if (!arena->freelist)
		return -ENOMEM;

	for (i = 0; i < arena->nfree; i++) {
		old = btt_log_read(arena, i, &log_old, LOG_OLD_ENT);
		if (old < 0)
			return old;

		new = btt_log_read(arena, i, &log_new, LOG_NEW_ENT);
		if (new < 0)
			return new;

		/* sub points to the next one to be overwritten */
		arena->freelist[i].sub = 1 - new;
		arena->freelist[i].seq = nd_inc_seq(le32_to_cpu(log_new.seq));
		arena->freelist[i].block = le32_to_cpu(log_new.old_map);

		/* This implies a newly created or untouched flog entry */
		if (log_new.old_map == log_new.new_map)
			continue;

		/* Check if map recovery is needed */
		ret = btt_map_read(arena, le32_to_cpu(log_new.lba), &map_entry,
				NULL, NULL, 0);
		if (ret)
			return ret;
		if ((le32_to_cpu(log_new.new_map) != map_entry) &&
				(le32_to_cpu(log_new.old_map) == map_entry)) {
			/*
			 * Last transaction wrote the flog, but wasn't able
			 * to complete the map write. So fix up the map.
			 */
			ret = btt_map_write(arena, le32_to_cpu(log_new.lba),
					le32_to_cpu(log_new.new_map), 0, 0, 0);
			if (ret)
				return ret;
		}

	}

	return 0;
}

static int btt_rtt_init(struct arena_info *arena)
{
	arena->rtt = kcalloc(arena->nfree, sizeof(u32), GFP_KERNEL);
	if (arena->rtt == NULL)
		return -ENOMEM;

	return 0;
}

static int btt_maplocks_init(struct arena_info *arena)
{
	u32 i;

	arena->map_locks = kcalloc(arena->nfree, sizeof(struct aligned_lock),
				GFP_KERNEL);
	if (!arena->map_locks)
		return -ENOMEM;

	for (i = 0; i < arena->nfree; i++)
		spin_lock_init(&arena->map_locks[i].lock);

	return 0;
}

static struct arena_info *alloc_arena(struct btt *btt, size_t size,
				size_t start, size_t arena_off)
{
	struct arena_info *arena;
	u64 logsize, mapsize, datasize;
	u64 available = size;

	arena = kzalloc(sizeof(struct arena_info), GFP_KERNEL);
	if (!arena)
		return NULL;
	arena->nd_btt = btt->nd_btt;

	if (!size)
		return arena;

	arena->size = size;
	arena->external_lba_start = start;
	arena->external_lbasize = btt->lbasize;
	arena->internal_lbasize = roundup(arena->external_lbasize,
					INT_LBASIZE_ALIGNMENT);
	arena->nfree = BTT_DEFAULT_NFREE;
	arena->version_major = 1;
	arena->version_minor = 1;

	if (available % BTT_PG_SIZE)
		available -= (available % BTT_PG_SIZE);

	/* Two pages are reserved for the super block and its copy */
	available -= 2 * BTT_PG_SIZE;

	/* The log takes a fixed amount of space based on nfree */
	logsize = roundup(2 * arena->nfree * sizeof(struct log_entry),
				BTT_PG_SIZE);
	available -= logsize;

	/* Calculate optimal split between map and data area */
	arena->internal_nlba = div_u64(available - BTT_PG_SIZE,
			arena->internal_lbasize + MAP_ENT_SIZE);
	arena->external_nlba = arena->internal_nlba - arena->nfree;

	mapsize = roundup((arena->external_nlba * MAP_ENT_SIZE), BTT_PG_SIZE);
	datasize = available - mapsize;

	/* 'Absolute' values, relative to start of storage space */
	arena->infooff = arena_off;
	arena->dataoff = arena->infooff + BTT_PG_SIZE;
	arena->mapoff = arena->dataoff + datasize;
	arena->logoff = arena->mapoff + mapsize;
	arena->info2off = arena->logoff + logsize;
	return arena;
}

static void free_arenas(struct btt *btt)
{
	struct arena_info *arena, *next;

	list_for_each_entry_safe(arena, next, &btt->arena_list, list) {
		list_del(&arena->list);
		kfree(arena->rtt);
		kfree(arena->map_locks);
		kfree(arena->freelist);
		debugfs_remove_recursive(arena->debugfs_dir);
		kfree(arena);
	}
}

/*
 * This function reads an existing valid btt superblock and
 * populates the corresponding arena_info struct
 */
static void parse_arena_meta(struct arena_info *arena, struct btt_sb *super,
				u64 arena_off)
{
	arena->internal_nlba = le32_to_cpu(super->internal_nlba);
	arena->internal_lbasize = le32_to_cpu(super->internal_lbasize);
	arena->external_nlba = le32_to_cpu(super->external_nlba);
	arena->external_lbasize = le32_to_cpu(super->external_lbasize);
	arena->nfree = le32_to_cpu(super->nfree);
	arena->version_major = le16_to_cpu(super->version_major);
	arena->version_minor = le16_to_cpu(super->version_minor);

	arena->nextoff = (super->nextoff == 0) ? 0 : (arena_off +
			le64_to_cpu(super->nextoff));
	arena->infooff = arena_off;
	arena->dataoff = arena_off + le64_to_cpu(super->dataoff);
	arena->mapoff = arena_off + le64_to_cpu(super->mapoff);
	arena->logoff = arena_off + le64_to_cpu(super->logoff);
	arena->info2off = arena_off + le64_to_cpu(super->info2off);

	arena->size = (le64_to_cpu(super->nextoff) > 0)
		? (le64_to_cpu(super->nextoff))
		: (arena->info2off - arena->infooff + BTT_PG_SIZE);

	arena->flags = le32_to_cpu(super->flags);
}

static int discover_arenas(struct btt *btt)
{
	int ret = 0;
	struct arena_info *arena;
	struct btt_sb *super;
	size_t remaining = btt->rawsize;
	u64 cur_nlba = 0;
	size_t cur_off = 0;
	int num_arenas = 0;

	super = kzalloc(sizeof(*super), GFP_KERNEL);
	if (!super)
		return -ENOMEM;

	while (remaining) {
		/* Alloc memory for arena */
		arena = alloc_arena(btt, 0, 0, 0);
		if (!arena) {
			ret = -ENOMEM;
			goto out_super;
		}

		arena->infooff = cur_off;
		ret = btt_info_read(arena, super);
		if (ret)
			goto out;

		if (!nd_btt_arena_is_valid(btt->nd_btt, super)) {
			if (remaining == btt->rawsize) {
				btt->init_state = INIT_NOTFOUND;
				dev_info(to_dev(arena), "No existing arenas\n");
				goto out;
			} else {
				dev_info(to_dev(arena),
						"Found corrupted metadata!\n");
				ret = -ENODEV;
				goto out;
			}
		}

		arena->external_lba_start = cur_nlba;
		parse_arena_meta(arena, super, cur_off);

		ret = btt_freelist_init(arena);
		if (ret)
			goto out;

		ret = btt_rtt_init(arena);
		if (ret)
			goto out;

		ret = btt_maplocks_init(arena);
		if (ret)
			goto out;

		list_add_tail(&arena->list, &btt->arena_list);

		remaining -= arena->size;
		cur_off += arena->size;
		cur_nlba += arena->external_nlba;
		num_arenas++;

		if (arena->nextoff == 0)
			break;
	}
	btt->num_arenas = num_arenas;
	btt->nlba = cur_nlba;
	btt->init_state = INIT_READY;

	kfree(super);
	return ret;

 out:
	kfree(arena);
	free_arenas(btt);
 out_super:
	kfree(super);
	return ret;
}

static int create_arenas(struct btt *btt)
{
	size_t remaining = btt->rawsize;
	size_t cur_off = 0;

	while (remaining) {
		struct arena_info *arena;
		size_t arena_size = min_t(u64, ARENA_MAX_SIZE, remaining);

		remaining -= arena_size;
		if (arena_size < ARENA_MIN_SIZE)
			break;

		arena = alloc_arena(btt, arena_size, btt->nlba, cur_off);
		if (!arena) {
			free_arenas(btt);
			return -ENOMEM;
		}
		btt->nlba += arena->external_nlba;
		if (remaining >= ARENA_MIN_SIZE)
			arena->nextoff = arena->size;
		else
			arena->nextoff = 0;
		cur_off += arena_size;
		list_add_tail(&arena->list, &btt->arena_list);
	}

	return 0;
}

/*
 * This function completes arena initialization by writing
 * all the metadata.
 * It is only called for an uninitialized arena when a write
 * to that arena occurs for the first time.
 */
static int btt_arena_write_layout(struct arena_info *arena)
{
	int ret;
	u64 sum;
	struct btt_sb *super;
	struct nd_btt *nd_btt = arena->nd_btt;
	const u8 *parent_uuid = nd_dev_to_uuid(&nd_btt->ndns->dev);

	ret = btt_map_init(arena);
	if (ret)
		return ret;

	ret = btt_log_init(arena);
	if (ret)
		return ret;

	super = kzalloc(sizeof(struct btt_sb), GFP_NOIO);
	if (!super)
		return -ENOMEM;

	strncpy(super->signature, BTT_SIG, BTT_SIG_LEN);
	memcpy(super->uuid, nd_btt->uuid, 16);
	memcpy(super->parent_uuid, parent_uuid, 16);
	super->flags = cpu_to_le32(arena->flags);
	super->version_major = cpu_to_le16(arena->version_major);
	super->version_minor = cpu_to_le16(arena->version_minor);
	super->external_lbasize = cpu_to_le32(arena->external_lbasize);
	super->external_nlba = cpu_to_le32(arena->external_nlba);
	super->internal_lbasize = cpu_to_le32(arena->internal_lbasize);
	super->internal_nlba = cpu_to_le32(arena->internal_nlba);
	super->nfree = cpu_to_le32(arena->nfree);
	super->infosize = cpu_to_le32(sizeof(struct btt_sb));
	super->nextoff = cpu_to_le64(arena->nextoff);
	/*
	 * Subtract arena->infooff (arena start) so numbers are relative
	 * to 'this' arena
	 */
	super->dataoff = cpu_to_le64(arena->dataoff - arena->infooff);
	super->mapoff = cpu_to_le64(arena->mapoff - arena->infooff);
	super->logoff = cpu_to_le64(arena->logoff - arena->infooff);
	super->info2off = cpu_to_le64(arena->info2off - arena->infooff);

	super->flags = 0;
	sum = nd_sb_checksum((struct nd_gen_sb *) super);
	super->checksum = cpu_to_le64(sum);

	ret = btt_info_write(arena, super);

	kfree(super);
	return ret;
}

/*
 * This function completes the initialization for the BTT namespace
 * such that it is ready to accept IOs
 */
static int btt_meta_init(struct btt *btt)
{
	int ret = 0;
	struct arena_info *arena;

	mutex_lock(&btt->init_lock);
	list_for_each_entry(arena, &btt->arena_list, list) {
		ret = btt_arena_write_layout(arena);
		if (ret)
			goto unlock;

		ret = btt_freelist_init(arena);
		if (ret)
			goto unlock;

		ret = btt_rtt_init(arena);
		if (ret)
			goto unlock;

		ret = btt_maplocks_init(arena);
		if (ret)
			goto unlock;
	}

	btt->init_state = INIT_READY;

 unlock:
	mutex_unlock(&btt->init_lock);
	return ret;
}

static u32 btt_meta_size(struct btt *btt)
{
	return btt->lbasize - btt->sector_size;
}

/*
 * This function calculates the arena in which the given LBA lies
 * by doing a linear walk. This is acceptable since we expect only
 * a few arenas. If we have backing devices that get much larger,
 * we can construct a balanced binary tree of arenas at init time
 * so that this range search becomes faster.
 */
static int lba_to_arena(struct btt *btt, sector_t sector, __u32 *premap,
				struct arena_info **arena)
{
	struct arena_info *arena_list;
	__u64 lba = div_u64(sector << SECTOR_SHIFT, btt->sector_size);

	list_for_each_entry(arena_list, &btt->arena_list, list) {
		if (lba < arena_list->external_nlba) {
			*arena = arena_list;
			*premap = lba;
			return 0;
		}
		lba -= arena_list->external_nlba;
	}

	return -EIO;
}

/*
 * The following (lock_map, unlock_map) are mostly just to improve
 * readability, since they index into an array of locks
 */
static void lock_map(struct arena_info *arena, u32 premap)
		__acquires(&arena->map_locks[idx].lock)
{
	u32 idx = (premap * MAP_ENT_SIZE / L1_CACHE_BYTES) % arena->nfree;

	spin_lock(&arena->map_locks[idx].lock);
}

static void unlock_map(struct arena_info *arena, u32 premap)
		__releases(&arena->map_locks[idx].lock)
{
	u32 idx = (premap * MAP_ENT_SIZE / L1_CACHE_BYTES) % arena->nfree;

	spin_unlock(&arena->map_locks[idx].lock);
}

static u64 to_namespace_offset(struct arena_info *arena, u64 lba)
{
	return arena->dataoff + ((u64)lba * arena->internal_lbasize);
}

static int btt_data_read(struct arena_info *arena, struct page *page,
			unsigned int off, u32 lba, u32 len)
{
	int ret;
	u64 nsoff = to_namespace_offset(arena, lba);
	void *mem = kmap_atomic(page);

	ret = arena_read_bytes(arena, nsoff, mem + off, len, NVDIMM_IO_ATOMIC);
	kunmap_atomic(mem);

	return ret;
}

static int btt_data_write(struct arena_info *arena, u32 lba,
			struct page *page, unsigned int off, u32 len)
{
	int ret;
	u64 nsoff = to_namespace_offset(arena, lba);
	void *mem = kmap_atomic(page);

	ret = arena_write_bytes(arena, nsoff, mem + off, len, NVDIMM_IO_ATOMIC);
	kunmap_atomic(mem);

	return ret;
}

static void zero_fill_data(struct page *page, unsigned int off, u32 len)
{
	void *mem = kmap_atomic(page);

	memset(mem + off, 0, len);
	kunmap_atomic(mem);
}

#ifdef CONFIG_BLK_DEV_INTEGRITY
static int btt_rw_integrity(struct btt *btt, struct bio_integrity_payload *bip,
			struct arena_info *arena, u32 postmap, int rw)
{
	unsigned int len = btt_meta_size(btt);
	u64 meta_nsoff;
	int ret = 0;

	if (bip == NULL)
		return 0;

	meta_nsoff = to_namespace_offset(arena, postmap) + btt->sector_size;

	while (len) {
		unsigned int cur_len;
		struct bio_vec bv;
		void *mem;

		bv = bvec_iter_bvec(bip->bip_vec, bip->bip_iter);
		/*
		 * The 'bv' obtained from bvec_iter_bvec has its .bv_len and
		 * .bv_offset already adjusted for iter->bi_bvec_done, and we
		 * can use those directly
		 */

		cur_len = min(len, bv.bv_len);
		mem = kmap_atomic(bv.bv_page);
		if (rw)
			ret = arena_write_bytes(arena, meta_nsoff,
					mem + bv.bv_offset, cur_len,
					NVDIMM_IO_ATOMIC);
		else
			ret = arena_read_bytes(arena, meta_nsoff,
					mem + bv.bv_offset, cur_len,
					NVDIMM_IO_ATOMIC);

		kunmap_atomic(mem);
		if (ret)
			return ret;

		len -= cur_len;
		meta_nsoff += cur_len;
		bvec_iter_advance(bip->bip_vec, &bip->bip_iter, cur_len);
	}

	return ret;
}

#else /* CONFIG_BLK_DEV_INTEGRITY */
static int btt_rw_integrity(struct btt *btt, struct bio_integrity_payload *bip,
			struct arena_info *arena, u32 postmap, int rw)
{
	return 0;
}
#endif

static int btt_read_pg(struct btt *btt, struct bio_integrity_payload *bip,
			struct page *page, unsigned int off, sector_t sector,
			unsigned int len)
{
	int ret = 0;
	int t_flag, e_flag;
	struct arena_info *arena = NULL;
	u32 lane = 0, premap, postmap;

	while (len) {
		u32 cur_len;

		lane = nd_region_acquire_lane(btt->nd_region);

		ret = lba_to_arena(btt, sector, &premap, &arena);
		if (ret)
			goto out_lane;

		cur_len = min(btt->sector_size, len);

		ret = btt_map_read(arena, premap, &postmap, &t_flag, &e_flag,
				NVDIMM_IO_ATOMIC);
		if (ret)
			goto out_lane;

		/*
		 * We loop to make sure that the post map LBA didn't change
		 * from under us between writing the RTT and doing the actual
		 * read.
		 */
		while (1) {
			u32 new_map;

			if (t_flag) {
				zero_fill_data(page, off, cur_len);
				goto out_lane;
			}

			if (e_flag) {
				ret = -EIO;
				goto out_lane;
			}

			arena->rtt[lane] = RTT_VALID | postmap;
			/*
			 * Barrier to make sure this write is not reordered
			 * to do the verification map_read before the RTT store
			 */
			barrier();

			ret = btt_map_read(arena, premap, &new_map, &t_flag,
						&e_flag, NVDIMM_IO_ATOMIC);
			if (ret)
				goto out_rtt;

			if (postmap == new_map)
				break;

			postmap = new_map;
		}

		ret = btt_data_read(arena, page, off, postmap, cur_len);
		if (ret)
			goto out_rtt;

		if (bip) {
			ret = btt_rw_integrity(btt, bip, arena, postmap, READ);
			if (ret)
				goto out_rtt;
		}

		arena->rtt[lane] = RTT_INVALID;
		nd_region_release_lane(btt->nd_region, lane);

		len -= cur_len;
		off += cur_len;
		sector += btt->sector_size >> SECTOR_SHIFT;
	}

	return 0;

 out_rtt:
	arena->rtt[lane] = RTT_INVALID;
 out_lane:
	nd_region_release_lane(btt->nd_region, lane);
	return ret;
}

static int btt_write_pg(struct btt *btt, struct bio_integrity_payload *bip,
			sector_t sector, struct page *page, unsigned int off,
			unsigned int len)
{
	int ret = 0;
	struct arena_info *arena = NULL;
	u32 premap = 0, old_postmap, new_postmap, lane = 0, i;
	struct log_entry log;
	int sub;

	while (len) {
		u32 cur_len;

		lane = nd_region_acquire_lane(btt->nd_region);

		ret = lba_to_arena(btt, sector, &premap, &arena);
		if (ret)
			goto out_lane;
		cur_len = min(btt->sector_size, len);

		if ((arena->flags & IB_FLAG_ERROR_MASK) != 0) {
			ret = -EIO;
			goto out_lane;
		}

		new_postmap = arena->freelist[lane].block;

		/* Wait if the new block is being read from */
		for (i = 0; i < arena->nfree; i++)
			while (arena->rtt[i] == (RTT_VALID | new_postmap))
				cpu_relax();


		if (new_postmap >= arena->internal_nlba) {
			ret = -EIO;
			goto out_lane;
		}

		ret = btt_data_write(arena, new_postmap, page, off, cur_len);
		if (ret)
			goto out_lane;

		if (bip) {
			ret = btt_rw_integrity(btt, bip, arena, new_postmap,
						WRITE);
			if (ret)
				goto out_lane;
		}

		lock_map(arena, premap);
		ret = btt_map_read(arena, premap, &old_postmap, NULL, NULL,
				NVDIMM_IO_ATOMIC);
		if (ret)
			goto out_map;
		if (old_postmap >= arena->internal_nlba) {
			ret = -EIO;
			goto out_map;
		}

		log.lba = cpu_to_le32(premap);
		log.old_map = cpu_to_le32(old_postmap);
		log.new_map = cpu_to_le32(new_postmap);
		log.seq = cpu_to_le32(arena->freelist[lane].seq);
		sub = arena->freelist[lane].sub;
		ret = btt_flog_write(arena, lane, sub, &log);
		if (ret)
			goto out_map;

		ret = btt_map_write(arena, premap, new_postmap, 0, 0, 0);
		if (ret)
			goto out_map;

		unlock_map(arena, premap);
		nd_region_release_lane(btt->nd_region, lane);

		len -= cur_len;
		off += cur_len;
		sector += btt->sector_size >> SECTOR_SHIFT;
	}

	return 0;

 out_map:
	unlock_map(arena, premap);
 out_lane:
	nd_region_release_lane(btt->nd_region, lane);
	return ret;
}

static int btt_do_bvec(struct btt *btt, struct bio_integrity_payload *bip,
			struct page *page, unsigned int len, unsigned int off,
			bool is_write, sector_t sector)
{
	int ret;

	if (!is_write) {
		ret = btt_read_pg(btt, bip, page, off, sector, len);
		flush_dcache_page(page);
	} else {
		flush_dcache_page(page);
		ret = btt_write_pg(btt, bip, sector, page, off, len);
	}

	return ret;
}

static blk_qc_t btt_make_request(struct request_queue *q, struct bio *bio)
{
	struct bio_integrity_payload *bip = bio_integrity(bio);
	struct btt *btt = q->queuedata;
	struct bvec_iter iter;
	unsigned long start;
	struct bio_vec bvec;
	int err = 0;
	bool do_acct;

	/*
	 * bio_integrity_enabled also checks if the bio already has an
	 * integrity payload attached. If it does, we *don't* do a
	 * bio_integrity_prep here - the payload has been generated by
	 * another kernel subsystem, and we just pass it through.
	 */
	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
		bio->bi_status = BLK_STS_IOERR;
		goto out;
	}

	do_acct = nd_iostat_start(bio, &start);
	bio_for_each_segment(bvec, bio, iter) {
		unsigned int len = bvec.bv_len;

		BUG_ON(len > PAGE_SIZE);
		/* Make sure len is in multiples of sector size. */
		/* XXX is this right? */
		BUG_ON(len < btt->sector_size);
		BUG_ON(len % btt->sector_size);

		err = btt_do_bvec(btt, bip, bvec.bv_page, len, bvec.bv_offset,
				  op_is_write(bio_op(bio)), iter.bi_sector);
		if (err) {
			dev_info(&btt->nd_btt->dev,
					"io error in %s sector %lld, len %d,\n",
					(op_is_write(bio_op(bio))) ? "WRITE" :
					"READ",
					(unsigned long long) iter.bi_sector, len);
			bio->bi_status = errno_to_blk_status(err);
			break;
		}
	}
	if (do_acct)
		nd_iostat_end(bio, start);

out:
	bio_endio(bio);
	return BLK_QC_T_NONE;
}

static int btt_rw_page(struct block_device *bdev, sector_t sector,
		struct page *page, bool is_write)
{
	struct btt *btt = bdev->bd_disk->private_data;

	btt_do_bvec(btt, NULL, page, PAGE_SIZE, 0, is_write, sector);
	page_endio(page, is_write, 0);
	return 0;
}


static int btt_getgeo(struct block_device *bd, struct hd_geometry *geo)
{
	/* some standard values */
	geo->heads = 1 << 6;
	geo->sectors = 1 << 5;
	geo->cylinders = get_capacity(bd->bd_disk) >> 11;
	return 0;
}

static const struct block_device_operations btt_fops = {
	.owner =		THIS_MODULE,
	.rw_page =		btt_rw_page,
	.getgeo =		btt_getgeo,
	.revalidate_disk =	nvdimm_revalidate_disk,
};

static int btt_blk_init(struct btt *btt)
{
	struct nd_btt *nd_btt = btt->nd_btt;
	struct nd_namespace_common *ndns = nd_btt->ndns;

	/* create a new disk and request queue for btt */
	btt->btt_queue = blk_alloc_queue(GFP_KERNEL);
	if (!btt->btt_queue)
		return -ENOMEM;

	btt->btt_disk = alloc_disk(0);
	if (!btt->btt_disk) {
		blk_cleanup_queue(btt->btt_queue);
		return -ENOMEM;
	}

	nvdimm_namespace_disk_name(ndns, btt->btt_disk->disk_name);
	btt->btt_disk->first_minor = 0;
	btt->btt_disk->fops = &btt_fops;
	btt->btt_disk->private_data = btt;
	btt->btt_disk->queue = btt->btt_queue;
	btt->btt_disk->flags = GENHD_FL_EXT_DEVT;

	blk_queue_make_request(btt->btt_queue, btt_make_request);
	blk_queue_logical_block_size(btt->btt_queue, btt->sector_size);
	blk_queue_max_hw_sectors(btt->btt_queue, UINT_MAX);
	queue_flag_set_unlocked(QUEUE_FLAG_NONROT, btt->btt_queue);
	btt->btt_queue->queuedata = btt;

	set_capacity(btt->btt_disk, 0);
	device_add_disk(&btt->nd_btt->dev, btt->btt_disk);
	if (btt_meta_size(btt)) {
		int rc = nd_integrity_init(btt->btt_disk, btt_meta_size(btt));

		if (rc) {
			del_gendisk(btt->btt_disk);
			put_disk(btt->btt_disk);
			blk_cleanup_queue(btt->btt_queue);
			return rc;
		}
	}
	set_capacity(btt->btt_disk, btt->nlba * btt->sector_size >> 9);
	btt->nd_btt->size = btt->nlba * (u64)btt->sector_size;
	revalidate_disk(btt->btt_disk);

	return 0;
}

static void btt_blk_cleanup(struct btt *btt)
{
	del_gendisk(btt->btt_disk);
	put_disk(btt->btt_disk);
	blk_cleanup_queue(btt->btt_queue);
}

/**
 * btt_init - initialize a block translation table for the given device
 * @nd_btt:	device with BTT geometry and backing device info
 * @rawsize:	raw size in bytes of the backing device
 * @lbasize:	lba size of the backing device
 * @uuid:	A uuid for the backing device - this is stored on media
 * @maxlane:	maximum number of parallel requests the device can handle
 *
 * Initialize a Block Translation Table on a backing device to provide
 * single sector power fail atomicity.
 *
 * Context:
 * Might sleep.
 *
 * Returns:
 * Pointer to a new struct btt on success, NULL on failure.
 */
static struct btt *btt_init(struct nd_btt *nd_btt, unsigned long long rawsize,
		u32 lbasize, u8 *uuid, struct nd_region *nd_region)
{
	int ret;
	struct btt *btt;
	struct device *dev = &nd_btt->dev;

	btt = devm_kzalloc(dev, sizeof(struct btt), GFP_KERNEL);
	if (!btt)
		return NULL;

	btt->nd_btt = nd_btt;
	btt->rawsize = rawsize;
	btt->lbasize = lbasize;
	btt->sector_size = ((lbasize >= 4096) ? 4096 : 512);
	INIT_LIST_HEAD(&btt->arena_list);
	mutex_init(&btt->init_lock);
	btt->nd_region = nd_region;

	ret = discover_arenas(btt);
	if (ret) {
		dev_err(dev, "init: error in arena_discover: %d\n", ret);
		return NULL;
	}

	if (btt->init_state != INIT_READY && nd_region->ro) {
		dev_info(dev, "%s is read-only, unable to init btt metadata\n",
				dev_name(&nd_region->dev));
		return NULL;
	} else if (btt->init_state != INIT_READY) {
		btt->num_arenas = (rawsize / ARENA_MAX_SIZE) +
			((rawsize % ARENA_MAX_SIZE) ? 1 : 0);
		dev_dbg(dev, "init: %d arenas for %llu rawsize\n",
				btt->num_arenas, rawsize);

		ret = create_arenas(btt);
		if (ret) {
			dev_info(dev, "init: create_arenas: %d\n", ret);
			return NULL;
		}

		ret = btt_meta_init(btt);
		if (ret) {
			dev_err(dev, "init: error in meta_init: %d\n", ret);
			return NULL;
		}
	}

	ret = btt_blk_init(btt);
	if (ret) {
		dev_err(dev, "init: error in blk_init: %d\n", ret);
		return NULL;
	}

	btt_debugfs_init(btt);

	return btt;
}

/**
 * btt_fini - de-initialize a BTT
 * @btt:	the BTT handle that was generated by btt_init
 *
 * De-initialize a Block Translation Table on device removal
 *
 * Context:
 * Might sleep.
 */
static void btt_fini(struct btt *btt)
{
	if (btt) {
		btt_blk_cleanup(btt);
		free_arenas(btt);
		debugfs_remove_recursive(btt->debugfs_dir);
	}
}

int nvdimm_namespace_attach_btt(struct nd_namespace_common *ndns)
{
	struct nd_btt *nd_btt = to_nd_btt(ndns->claim);
	struct nd_region *nd_region;
	struct btt *btt;
	size_t rawsize;

	if (!nd_btt->uuid || !nd_btt->ndns || !nd_btt->lbasize) {
		dev_dbg(&nd_btt->dev, "incomplete btt configuration\n");
		return -ENODEV;
	}

	rawsize = nvdimm_namespace_capacity(ndns) - SZ_4K;
	if (rawsize < ARENA_MIN_SIZE) {
		dev_dbg(&nd_btt->dev, "%s must be at least %ld bytes\n",
				dev_name(&ndns->dev), ARENA_MIN_SIZE + SZ_4K);
		return -ENXIO;
	}
	nd_region = to_nd_region(nd_btt->dev.parent);
	btt = btt_init(nd_btt, rawsize, nd_btt->lbasize, nd_btt->uuid,
			nd_region);
	if (!btt)
		return -ENOMEM;
	nd_btt->btt = btt;

	return 0;
}
EXPORT_SYMBOL(nvdimm_namespace_attach_btt);

int nvdimm_namespace_detach_btt(struct nd_btt *nd_btt)
{
	struct btt *btt = nd_btt->btt;

	btt_fini(btt);
	nd_btt->btt = NULL;

	return 0;
}
EXPORT_SYMBOL(nvdimm_namespace_detach_btt);

static int __init nd_btt_init(void)
{
	int rc = 0;

	debugfs_root = debugfs_create_dir("btt", NULL);
	if (IS_ERR_OR_NULL(debugfs_root))
		rc = -ENXIO;

	return rc;
}

static void __exit nd_btt_exit(void)
{
	debugfs_remove_recursive(debugfs_root);
}

MODULE_ALIAS_ND_DEVICE(ND_DEVICE_BTT);
MODULE_AUTHOR("Vishal Verma <vishal.l.verma@linux.intel.com>");
MODULE_LICENSE("GPL v2");
module_init(nd_btt_init);
module_exit(nd_btt_exit);