summaryrefslogtreecommitdiff
path: root/drivers/scsi/cxlflash/vlun.c
blob: 703bf1e9a64a1dd5db0736d8319d1d2229097e69 (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
/*
 * CXL Flash Device Driver
 *
 * Written by: Manoj N. Kumar <manoj@linux.vnet.ibm.com>, IBM Corporation
 *             Matthew R. Ochs <mrochs@linux.vnet.ibm.com>, IBM Corporation
 *
 * Copyright (C) 2015 IBM Corporation
 *
 * 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.
 */

#include <linux/syscalls.h>
#include <misc/cxl.h>
#include <asm/unaligned.h>
#include <asm/bitsperlong.h>

#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
#include <uapi/scsi/cxlflash_ioctl.h>

#include "sislite.h"
#include "common.h"
#include "vlun.h"
#include "superpipe.h"

/**
 * marshal_virt_to_resize() - translate uvirtual to resize structure
 * @virt:	Source structure from which to translate/copy.
 * @resize:	Destination structure for the translate/copy.
 */
static void marshal_virt_to_resize(struct dk_cxlflash_uvirtual *virt,
				   struct dk_cxlflash_resize *resize)
{
	resize->hdr = virt->hdr;
	resize->context_id = virt->context_id;
	resize->rsrc_handle = virt->rsrc_handle;
	resize->req_size = virt->lun_size;
	resize->last_lba = virt->last_lba;
}

/**
 * marshal_clone_to_rele() - translate clone to release structure
 * @clone:	Source structure from which to translate/copy.
 * @rele:	Destination structure for the translate/copy.
 */
static void marshal_clone_to_rele(struct dk_cxlflash_clone *clone,
				  struct dk_cxlflash_release *release)
{
	release->hdr = clone->hdr;
	release->context_id = clone->context_id_dst;
}

/**
 * ba_init() - initializes a block allocator
 * @ba_lun:	Block allocator to initialize.
 *
 * Return: 0 on success, -errno on failure
 */
static int ba_init(struct ba_lun *ba_lun)
{
	struct ba_lun_info *bali = NULL;
	int lun_size_au = 0, i = 0;
	int last_word_underflow = 0;
	u64 *lam;

	pr_debug("%s: Initializing LUN: lun_id=%016llx "
		 "ba_lun->lsize=%lx ba_lun->au_size=%lX\n",
		__func__, ba_lun->lun_id, ba_lun->lsize, ba_lun->au_size);

	/* Calculate bit map size */
	lun_size_au = ba_lun->lsize / ba_lun->au_size;
	if (lun_size_au == 0) {
		pr_debug("%s: Requested LUN size of 0!\n", __func__);
		return -EINVAL;
	}

	/* Allocate lun information container */
	bali = kzalloc(sizeof(struct ba_lun_info), GFP_KERNEL);
	if (unlikely(!bali)) {
		pr_err("%s: Failed to allocate lun_info lun_id=%016llx\n",
		       __func__, ba_lun->lun_id);
		return -ENOMEM;
	}

	bali->total_aus = lun_size_au;
	bali->lun_bmap_size = lun_size_au / BITS_PER_LONG;

	if (lun_size_au % BITS_PER_LONG)
		bali->lun_bmap_size++;

	/* Allocate bitmap space */
	bali->lun_alloc_map = kzalloc((bali->lun_bmap_size * sizeof(u64)),
				      GFP_KERNEL);
	if (unlikely(!bali->lun_alloc_map)) {
		pr_err("%s: Failed to allocate lun allocation map: "
		       "lun_id=%016llx\n", __func__, ba_lun->lun_id);
		kfree(bali);
		return -ENOMEM;
	}

	/* Initialize the bit map size and set all bits to '1' */
	bali->free_aun_cnt = lun_size_au;

	for (i = 0; i < bali->lun_bmap_size; i++)
		bali->lun_alloc_map[i] = 0xFFFFFFFFFFFFFFFFULL;

	/* If the last word not fully utilized, mark extra bits as allocated */
	last_word_underflow = (bali->lun_bmap_size * BITS_PER_LONG);
	last_word_underflow -= bali->free_aun_cnt;
	if (last_word_underflow > 0) {
		lam = &bali->lun_alloc_map[bali->lun_bmap_size - 1];
		for (i = (HIBIT - last_word_underflow + 1);
		     i < BITS_PER_LONG;
		     i++)
			clear_bit(i, (ulong *)lam);
	}

	/* Initialize high elevator index, low/curr already at 0 from kzalloc */
	bali->free_high_idx = bali->lun_bmap_size;

	/* Allocate clone map */
	bali->aun_clone_map = kzalloc((bali->total_aus * sizeof(u8)),
				      GFP_KERNEL);
	if (unlikely(!bali->aun_clone_map)) {
		pr_err("%s: Failed to allocate clone map: lun_id=%016llx\n",
		       __func__, ba_lun->lun_id);
		kfree(bali->lun_alloc_map);
		kfree(bali);
		return -ENOMEM;
	}

	/* Pass the allocated LUN info as a handle to the user */
	ba_lun->ba_lun_handle = bali;

	pr_debug("%s: Successfully initialized the LUN: "
		 "lun_id=%016llx bitmap size=%x, free_aun_cnt=%llx\n",
		__func__, ba_lun->lun_id, bali->lun_bmap_size,
		bali->free_aun_cnt);
	return 0;
}

/**
 * find_free_range() - locates a free bit within the block allocator
 * @low:	First word in block allocator to start search.
 * @high:	Last word in block allocator to search.
 * @bali:	LUN information structure owning the block allocator to search.
 * @bit_word:	Passes back the word in the block allocator owning the free bit.
 *
 * Return: The bit position within the passed back word, -1 on failure
 */
static int find_free_range(u32 low,
			   u32 high,
			   struct ba_lun_info *bali, int *bit_word)
{
	int i;
	u64 bit_pos = -1;
	ulong *lam, num_bits;

	for (i = low; i < high; i++)
		if (bali->lun_alloc_map[i] != 0) {
			lam = (ulong *)&bali->lun_alloc_map[i];
			num_bits = (sizeof(*lam) * BITS_PER_BYTE);
			bit_pos = find_first_bit(lam, num_bits);

			pr_devel("%s: Found free bit %llu in LUN "
				 "map entry %016llx at bitmap index = %d\n",
				 __func__, bit_pos, bali->lun_alloc_map[i], i);

			*bit_word = i;
			bali->free_aun_cnt--;
			clear_bit(bit_pos, lam);
			break;
		}

	return bit_pos;
}

/**
 * ba_alloc() - allocates a block from the block allocator
 * @ba_lun:	Block allocator from which to allocate a block.
 *
 * Return: The allocated block, -1 on failure
 */
static u64 ba_alloc(struct ba_lun *ba_lun)
{
	u64 bit_pos = -1;
	int bit_word = 0;
	struct ba_lun_info *bali = NULL;

	bali = ba_lun->ba_lun_handle;

	pr_debug("%s: Received block allocation request: "
		 "lun_id=%016llx free_aun_cnt=%llx\n",
		 __func__, ba_lun->lun_id, bali->free_aun_cnt);

	if (bali->free_aun_cnt == 0) {
		pr_debug("%s: No space left on LUN: lun_id=%016llx\n",
			 __func__, ba_lun->lun_id);
		return -1ULL;
	}

	/* Search to find a free entry, curr->high then low->curr */
	bit_pos = find_free_range(bali->free_curr_idx,
				  bali->free_high_idx, bali, &bit_word);
	if (bit_pos == -1) {
		bit_pos = find_free_range(bali->free_low_idx,
					  bali->free_curr_idx,
					  bali, &bit_word);
		if (bit_pos == -1) {
			pr_debug("%s: Could not find an allocation unit on LUN:"
				 " lun_id=%016llx\n", __func__, ba_lun->lun_id);
			return -1ULL;
		}
	}

	/* Update the free_curr_idx */
	if (bit_pos == HIBIT)
		bali->free_curr_idx = bit_word + 1;
	else
		bali->free_curr_idx = bit_word;

	pr_debug("%s: Allocating AU number=%llx lun_id=%016llx "
		 "free_aun_cnt=%llx\n", __func__,
		 ((bit_word * BITS_PER_LONG) + bit_pos), ba_lun->lun_id,
		 bali->free_aun_cnt);

	return (u64) ((bit_word * BITS_PER_LONG) + bit_pos);
}

/**
 * validate_alloc() - validates the specified block has been allocated
 * @ba_lun_info:	LUN info owning the block allocator.
 * @aun:		Block to validate.
 *
 * Return: 0 on success, -1 on failure
 */
static int validate_alloc(struct ba_lun_info *bali, u64 aun)
{
	int idx = 0, bit_pos = 0;

	idx = aun / BITS_PER_LONG;
	bit_pos = aun % BITS_PER_LONG;

	if (test_bit(bit_pos, (ulong *)&bali->lun_alloc_map[idx]))
		return -1;

	return 0;
}

/**
 * ba_free() - frees a block from the block allocator
 * @ba_lun:	Block allocator from which to allocate a block.
 * @to_free:	Block to free.
 *
 * Return: 0 on success, -1 on failure
 */
static int ba_free(struct ba_lun *ba_lun, u64 to_free)
{
	int idx = 0, bit_pos = 0;
	struct ba_lun_info *bali = NULL;

	bali = ba_lun->ba_lun_handle;

	if (validate_alloc(bali, to_free)) {
		pr_debug("%s: AUN %llx is not allocated on lun_id=%016llx\n",
			 __func__, to_free, ba_lun->lun_id);
		return -1;
	}

	pr_debug("%s: Received a request to free AU=%llx lun_id=%016llx "
		 "free_aun_cnt=%llx\n", __func__, to_free, ba_lun->lun_id,
		 bali->free_aun_cnt);

	if (bali->aun_clone_map[to_free] > 0) {
		pr_debug("%s: AUN %llx lun_id=%016llx cloned. Clone count=%x\n",
			 __func__, to_free, ba_lun->lun_id,
			 bali->aun_clone_map[to_free]);
		bali->aun_clone_map[to_free]--;
		return 0;
	}

	idx = to_free / BITS_PER_LONG;
	bit_pos = to_free % BITS_PER_LONG;

	set_bit(bit_pos, (ulong *)&bali->lun_alloc_map[idx]);
	bali->free_aun_cnt++;

	if (idx < bali->free_low_idx)
		bali->free_low_idx = idx;
	else if (idx > bali->free_high_idx)
		bali->free_high_idx = idx;

	pr_debug("%s: Successfully freed AU bit_pos=%x bit map index=%x "
		 "lun_id=%016llx free_aun_cnt=%llx\n", __func__, bit_pos, idx,
		 ba_lun->lun_id, bali->free_aun_cnt);

	return 0;
}

/**
 * ba_clone() - Clone a chunk of the block allocation table
 * @ba_lun:	Block allocator from which to allocate a block.
 * @to_free:	Block to free.
 *
 * Return: 0 on success, -1 on failure
 */
static int ba_clone(struct ba_lun *ba_lun, u64 to_clone)
{
	struct ba_lun_info *bali = ba_lun->ba_lun_handle;

	if (validate_alloc(bali, to_clone)) {
		pr_debug("%s: AUN=%llx not allocated on lun_id=%016llx\n",
			 __func__, to_clone, ba_lun->lun_id);
		return -1;
	}

	pr_debug("%s: Received a request to clone AUN %llx on lun_id=%016llx\n",
		 __func__, to_clone, ba_lun->lun_id);

	if (bali->aun_clone_map[to_clone] == MAX_AUN_CLONE_CNT) {
		pr_debug("%s: AUN %llx on lun_id=%016llx hit max clones already\n",
			 __func__, to_clone, ba_lun->lun_id);
		return -1;
	}

	bali->aun_clone_map[to_clone]++;

	return 0;
}

/**
 * ba_space() - returns the amount of free space left in the block allocator
 * @ba_lun:	Block allocator.
 *
 * Return: Amount of free space in block allocator
 */
static u64 ba_space(struct ba_lun *ba_lun)
{
	struct ba_lun_info *bali = ba_lun->ba_lun_handle;

	return bali->free_aun_cnt;
}

/**
 * cxlflash_ba_terminate() - frees resources associated with the block allocator
 * @ba_lun:	Block allocator.
 *
 * Safe to call in a partially allocated state.
 */
void cxlflash_ba_terminate(struct ba_lun *ba_lun)
{
	struct ba_lun_info *bali = ba_lun->ba_lun_handle;

	if (bali) {
		kfree(bali->aun_clone_map);
		kfree(bali->lun_alloc_map);
		kfree(bali);
		ba_lun->ba_lun_handle = NULL;
	}
}

/**
 * init_vlun() - initializes a LUN for virtual use
 * @lun_info:	LUN information structure that owns the block allocator.
 *
 * Return: 0 on success, -errno on failure
 */
static int init_vlun(struct llun_info *lli)
{
	int rc = 0;
	struct glun_info *gli = lli->parent;
	struct blka *blka = &gli->blka;

	memset(blka, 0, sizeof(*blka));
	mutex_init(&blka->mutex);

	/* LUN IDs are unique per port, save the index instead */
	blka->ba_lun.lun_id = lli->lun_index;
	blka->ba_lun.lsize = gli->max_lba + 1;
	blka->ba_lun.lba_size = gli->blk_len;

	blka->ba_lun.au_size = MC_CHUNK_SIZE;
	blka->nchunk = blka->ba_lun.lsize / MC_CHUNK_SIZE;

	rc = ba_init(&blka->ba_lun);
	if (unlikely(rc))
		pr_debug("%s: cannot init block_alloc, rc=%d\n", __func__, rc);

	pr_debug("%s: returning rc=%d lli=%p\n", __func__, rc, lli);
	return rc;
}

/**
 * write_same16() - sends a SCSI WRITE_SAME16 (0) command to specified LUN
 * @sdev:	SCSI device associated with LUN.
 * @lba:	Logical block address to start write same.
 * @nblks:	Number of logical blocks to write same.
 *
 * The SCSI WRITE_SAME16 can take quite a while to complete. Should an EEH occur
 * while in scsi_execute(), the EEH handler will attempt to recover. As part of
 * the recovery, the handler drains all currently running ioctls, waiting until
 * they have completed before proceeding with a reset. As this routine is used
 * on the ioctl path, this can create a condition where the EEH handler becomes
 * stuck, infinitely waiting for this ioctl thread. To avoid this behavior,
 * temporarily unmark this thread as an ioctl thread by releasing the ioctl read
 * semaphore. This will allow the EEH handler to proceed with a recovery while
 * this thread is still running. Once the scsi_execute() returns, reacquire the
 * ioctl read semaphore and check the adapter state in case it changed while
 * inside of scsi_execute(). The state check will wait if the adapter is still
 * being recovered or return a failure if the recovery failed. In the event that
 * the adapter reset failed, simply return the failure as the ioctl would be
 * unable to continue.
 *
 * Note that the above puts a requirement on this routine to only be called on
 * an ioctl thread.
 *
 * Return: 0 on success, -errno on failure
 */
static int write_same16(struct scsi_device *sdev,
			u64 lba,
			u32 nblks)
{
	u8 *cmd_buf = NULL;
	u8 *scsi_cmd = NULL;
	u8 *sense_buf = NULL;
	int rc = 0;
	int result = 0;
	int ws_limit = SISLITE_MAX_WS_BLOCKS;
	u64 offset = lba;
	int left = nblks;
	u32 to = sdev->request_queue->rq_timeout;
	struct cxlflash_cfg *cfg = shost_priv(sdev->host);
	struct device *dev = &cfg->dev->dev;

	cmd_buf = kzalloc(CMD_BUFSIZE, GFP_KERNEL);
	scsi_cmd = kzalloc(MAX_COMMAND_SIZE, GFP_KERNEL);
	sense_buf = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);
	if (unlikely(!cmd_buf || !scsi_cmd || !sense_buf)) {
		rc = -ENOMEM;
		goto out;
	}

	while (left > 0) {

		scsi_cmd[0] = WRITE_SAME_16;
		scsi_cmd[1] = cfg->ws_unmap ? 0x8 : 0;
		put_unaligned_be64(offset, &scsi_cmd[2]);
		put_unaligned_be32(ws_limit < left ? ws_limit : left,
				   &scsi_cmd[10]);

		/* Drop the ioctl read semahpore across lengthy call */
		up_read(&cfg->ioctl_rwsem);
		result = scsi_execute(sdev, scsi_cmd, DMA_TO_DEVICE, cmd_buf,
				      CMD_BUFSIZE, sense_buf, NULL, to,
				      CMD_RETRIES, 0, 0, NULL);
		down_read(&cfg->ioctl_rwsem);
		rc = check_state(cfg);
		if (rc) {
			dev_err(dev, "%s: Failed state result=%08x\n",
				__func__, result);
			rc = -ENODEV;
			goto out;
		}

		if (result) {
			dev_err_ratelimited(dev, "%s: command failed for "
					    "offset=%lld result=%08x\n",
					    __func__, offset, result);
			rc = -EIO;
			goto out;
		}
		left -= ws_limit;
		offset += ws_limit;
	}

out:
	kfree(cmd_buf);
	kfree(scsi_cmd);
	kfree(sense_buf);
	dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
	return rc;
}

/**
 * grow_lxt() - expands the translation table associated with the specified RHTE
 * @afu:	AFU associated with the host.
 * @sdev:	SCSI device associated with LUN.
 * @ctxid:	Context ID of context owning the RHTE.
 * @rhndl:	Resource handle associated with the RHTE.
 * @rhte:	Resource handle entry (RHTE).
 * @new_size:	Number of translation entries associated with RHTE.
 *
 * By design, this routine employs a 'best attempt' allocation and will
 * truncate the requested size down if there is not sufficient space in
 * the block allocator to satisfy the request but there does exist some
 * amount of space. The user is made aware of this by returning the size
 * allocated.
 *
 * Return: 0 on success, -errno on failure
 */
static int grow_lxt(struct afu *afu,
		    struct scsi_device *sdev,
		    ctx_hndl_t ctxid,
		    res_hndl_t rhndl,
		    struct sisl_rht_entry *rhte,
		    u64 *new_size)
{
	struct cxlflash_cfg *cfg = shost_priv(sdev->host);
	struct device *dev = &cfg->dev->dev;
	struct sisl_lxt_entry *lxt = NULL, *lxt_old = NULL;
	struct llun_info *lli = sdev->hostdata;
	struct glun_info *gli = lli->parent;
	struct blka *blka = &gli->blka;
	u32 av_size;
	u32 ngrps, ngrps_old;
	u64 aun;		/* chunk# allocated by block allocator */
	u64 delta = *new_size - rhte->lxt_cnt;
	u64 my_new_size;
	int i, rc = 0;

	/*
	 * Check what is available in the block allocator before re-allocating
	 * LXT array. This is done up front under the mutex which must not be
	 * released until after allocation is complete.
	 */
	mutex_lock(&blka->mutex);
	av_size = ba_space(&blka->ba_lun);
	if (unlikely(av_size <= 0)) {
		dev_dbg(dev, "%s: ba_space error av_size=%d\n",
			__func__, av_size);
		mutex_unlock(&blka->mutex);
		rc = -ENOSPC;
		goto out;
	}

	if (av_size < delta)
		delta = av_size;

	lxt_old = rhte->lxt_start;
	ngrps_old = LXT_NUM_GROUPS(rhte->lxt_cnt);
	ngrps = LXT_NUM_GROUPS(rhte->lxt_cnt + delta);

	if (ngrps != ngrps_old) {
		/* reallocate to fit new size */
		lxt = kzalloc((sizeof(*lxt) * LXT_GROUP_SIZE * ngrps),
			      GFP_KERNEL);
		if (unlikely(!lxt)) {
			mutex_unlock(&blka->mutex);
			rc = -ENOMEM;
			goto out;
		}

		/* copy over all old entries */
		memcpy(lxt, lxt_old, (sizeof(*lxt) * rhte->lxt_cnt));
	} else
		lxt = lxt_old;

	/* nothing can fail from now on */
	my_new_size = rhte->lxt_cnt + delta;

	/* add new entries to the end */
	for (i = rhte->lxt_cnt; i < my_new_size; i++) {
		/*
		 * Due to the earlier check of available space, ba_alloc
		 * cannot fail here. If it did due to internal error,
		 * leave a rlba_base of -1u which will likely be a
		 * invalid LUN (too large).
		 */
		aun = ba_alloc(&blka->ba_lun);
		if ((aun == -1ULL) || (aun >= blka->nchunk))
			dev_dbg(dev, "%s: ba_alloc error allocated chunk=%llu "
				"max=%llu\n", __func__, aun, blka->nchunk - 1);

		/* select both ports, use r/w perms from RHT */
		lxt[i].rlba_base = ((aun << MC_CHUNK_SHIFT) |
				    (lli->lun_index << LXT_LUNIDX_SHIFT) |
				    (RHT_PERM_RW << LXT_PERM_SHIFT |
				     lli->port_sel));
	}

	mutex_unlock(&blka->mutex);

	/*
	 * The following sequence is prescribed in the SISlite spec
	 * for syncing up with the AFU when adding LXT entries.
	 */
	dma_wmb(); /* Make LXT updates are visible */

	rhte->lxt_start = lxt;
	dma_wmb(); /* Make RHT entry's LXT table update visible */

	rhte->lxt_cnt = my_new_size;
	dma_wmb(); /* Make RHT entry's LXT table size update visible */

	rc = cxlflash_afu_sync(afu, ctxid, rhndl, AFU_LW_SYNC);
	if (unlikely(rc))
		rc = -EAGAIN;

	/* free old lxt if reallocated */
	if (lxt != lxt_old)
		kfree(lxt_old);
	*new_size = my_new_size;
out:
	dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
	return rc;
}

/**
 * shrink_lxt() - reduces translation table associated with the specified RHTE
 * @afu:	AFU associated with the host.
 * @sdev:	SCSI device associated with LUN.
 * @rhndl:	Resource handle associated with the RHTE.
 * @rhte:	Resource handle entry (RHTE).
 * @ctxi:	Context owning resources.
 * @new_size:	Number of translation entries associated with RHTE.
 *
 * Return: 0 on success, -errno on failure
 */
static int shrink_lxt(struct afu *afu,
		      struct scsi_device *sdev,
		      res_hndl_t rhndl,
		      struct sisl_rht_entry *rhte,
		      struct ctx_info *ctxi,
		      u64 *new_size)
{
	struct cxlflash_cfg *cfg = shost_priv(sdev->host);
	struct device *dev = &cfg->dev->dev;
	struct sisl_lxt_entry *lxt, *lxt_old;
	struct llun_info *lli = sdev->hostdata;
	struct glun_info *gli = lli->parent;
	struct blka *blka = &gli->blka;
	ctx_hndl_t ctxid = DECODE_CTXID(ctxi->ctxid);
	bool needs_ws = ctxi->rht_needs_ws[rhndl];
	bool needs_sync = !ctxi->err_recovery_active;
	u32 ngrps, ngrps_old;
	u64 aun;		/* chunk# allocated by block allocator */
	u64 delta = rhte->lxt_cnt - *new_size;
	u64 my_new_size;
	int i, rc = 0;

	lxt_old = rhte->lxt_start;
	ngrps_old = LXT_NUM_GROUPS(rhte->lxt_cnt);
	ngrps = LXT_NUM_GROUPS(rhte->lxt_cnt - delta);

	if (ngrps != ngrps_old) {
		/* Reallocate to fit new size unless new size is 0 */
		if (ngrps) {
			lxt = kzalloc((sizeof(*lxt) * LXT_GROUP_SIZE * ngrps),
				      GFP_KERNEL);
			if (unlikely(!lxt)) {
				rc = -ENOMEM;
				goto out;
			}

			/* Copy over old entries that will remain */
			memcpy(lxt, lxt_old,
			       (sizeof(*lxt) * (rhte->lxt_cnt - delta)));
		} else
			lxt = NULL;
	} else
		lxt = lxt_old;

	/* Nothing can fail from now on */
	my_new_size = rhte->lxt_cnt - delta;

	/*
	 * The following sequence is prescribed in the SISlite spec
	 * for syncing up with the AFU when removing LXT entries.
	 */
	rhte->lxt_cnt = my_new_size;
	dma_wmb(); /* Make RHT entry's LXT table size update visible */

	rhte->lxt_start = lxt;
	dma_wmb(); /* Make RHT entry's LXT table update visible */

	if (needs_sync) {
		rc = cxlflash_afu_sync(afu, ctxid, rhndl, AFU_HW_SYNC);
		if (unlikely(rc))
			rc = -EAGAIN;
	}

	if (needs_ws) {
		/*
		 * Mark the context as unavailable, so that we can release
		 * the mutex safely.
		 */
		ctxi->unavail = true;
		mutex_unlock(&ctxi->mutex);
	}

	/* Free LBAs allocated to freed chunks */
	mutex_lock(&blka->mutex);
	for (i = delta - 1; i >= 0; i--) {
		aun = lxt_old[my_new_size + i].rlba_base >> MC_CHUNK_SHIFT;
		if (needs_ws)
			write_same16(sdev, aun, MC_CHUNK_SIZE);
		ba_free(&blka->ba_lun, aun);
	}
	mutex_unlock(&blka->mutex);

	if (needs_ws) {
		/* Make the context visible again */
		mutex_lock(&ctxi->mutex);
		ctxi->unavail = false;
	}

	/* Free old lxt if reallocated */
	if (lxt != lxt_old)
		kfree(lxt_old);
	*new_size = my_new_size;
out:
	dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
	return rc;
}

/**
 * _cxlflash_vlun_resize() - changes the size of a virtual LUN
 * @sdev:	SCSI device associated with LUN owning virtual LUN.
 * @ctxi:	Context owning resources.
 * @resize:	Resize ioctl data structure.
 *
 * On successful return, the user is informed of the new size (in blocks)
 * of the virtual LUN in last LBA format. When the size of the virtual
 * LUN is zero, the last LBA is reflected as -1. See comment in the
 * prologue for _cxlflash_disk_release() regarding AFU syncs and contexts
 * on the error recovery list.
 *
 * Return: 0 on success, -errno on failure
 */
int _cxlflash_vlun_resize(struct scsi_device *sdev,
			  struct ctx_info *ctxi,
			  struct dk_cxlflash_resize *resize)
{
	struct cxlflash_cfg *cfg = shost_priv(sdev->host);
	struct device *dev = &cfg->dev->dev;
	struct llun_info *lli = sdev->hostdata;
	struct glun_info *gli = lli->parent;
	struct afu *afu = cfg->afu;
	bool put_ctx = false;

	res_hndl_t rhndl = resize->rsrc_handle;
	u64 new_size;
	u64 nsectors;
	u64 ctxid = DECODE_CTXID(resize->context_id),
	    rctxid = resize->context_id;

	struct sisl_rht_entry *rhte;

	int rc = 0;

	/*
	 * The requested size (req_size) is always assumed to be in 4k blocks,
	 * so we have to convert it here from 4k to chunk size.
	 */
	nsectors = (resize->req_size * CXLFLASH_BLOCK_SIZE) / gli->blk_len;
	new_size = DIV_ROUND_UP(nsectors, MC_CHUNK_SIZE);

	dev_dbg(dev, "%s: ctxid=%llu rhndl=%llu req_size=%llu new_size=%llu\n",
		__func__, ctxid, resize->rsrc_handle, resize->req_size,
		new_size);

	if (unlikely(gli->mode != MODE_VIRTUAL)) {
		dev_dbg(dev, "%s: LUN mode does not support resize mode=%d\n",
			__func__, gli->mode);
		rc = -EINVAL;
		goto out;

	}

	if (!ctxi) {
		ctxi = get_context(cfg, rctxid, lli, CTX_CTRL_ERR_FALLBACK);
		if (unlikely(!ctxi)) {
			dev_dbg(dev, "%s: Bad context ctxid=%llu\n",
				__func__, ctxid);
			rc = -EINVAL;
			goto out;
		}

		put_ctx = true;
	}

	rhte = get_rhte(ctxi, rhndl, lli);
	if (unlikely(!rhte)) {
		dev_dbg(dev, "%s: Bad resource handle rhndl=%u\n",
			__func__, rhndl);
		rc = -EINVAL;
		goto out;
	}

	if (new_size > rhte->lxt_cnt)
		rc = grow_lxt(afu, sdev, ctxid, rhndl, rhte, &new_size);
	else if (new_size < rhte->lxt_cnt)
		rc = shrink_lxt(afu, sdev, rhndl, rhte, ctxi, &new_size);
	else {
		/*
		 * Rare case where there is already sufficient space, just
		 * need to perform a translation sync with the AFU. This
		 * scenario likely follows a previous sync failure during
		 * a resize operation. Accordingly, perform the heavyweight
		 * form of translation sync as it is unknown which type of
		 * resize failed previously.
		 */
		rc = cxlflash_afu_sync(afu, ctxid, rhndl, AFU_HW_SYNC);
		if (unlikely(rc)) {
			rc = -EAGAIN;
			goto out;
		}
	}

	resize->hdr.return_flags = 0;
	resize->last_lba = (new_size * MC_CHUNK_SIZE * gli->blk_len);
	resize->last_lba /= CXLFLASH_BLOCK_SIZE;
	resize->last_lba--;

out:
	if (put_ctx)
		put_context(ctxi);
	dev_dbg(dev, "%s: resized to %llu returning rc=%d\n",
		__func__, resize->last_lba, rc);
	return rc;
}

int cxlflash_vlun_resize(struct scsi_device *sdev,
			 struct dk_cxlflash_resize *resize)
{
	return _cxlflash_vlun_resize(sdev, NULL, resize);
}

/**
 * cxlflash_restore_luntable() - Restore LUN table to prior state
 * @cfg:	Internal structure associated with the host.
 */
void cxlflash_restore_luntable(struct cxlflash_cfg *cfg)
{
	struct llun_info *lli, *temp;
	u32 lind;
	int k;
	struct device *dev = &cfg->dev->dev;
	__be64 __iomem *fc_port_luns;

	mutex_lock(&global.mutex);

	list_for_each_entry_safe(lli, temp, &cfg->lluns, list) {
		if (!lli->in_table)
			continue;

		lind = lli->lun_index;
		dev_dbg(dev, "%s: Virtual LUNs on slot %d:\n", __func__, lind);

		for (k = 0; k < cfg->num_fc_ports; k++)
			if (lli->port_sel & (1 << k)) {
				fc_port_luns = get_fc_port_luns(cfg, k);
				writeq_be(lli->lun_id[k], &fc_port_luns[lind]);
				dev_dbg(dev, "\t%d=%llx\n", k, lli->lun_id[k]);
			}
	}

	mutex_unlock(&global.mutex);
}

/**
 * get_num_ports() - compute number of ports from port selection mask
 * @psm:	Port selection mask.
 *
 * Return: Population count of port selection mask
 */
static inline u8 get_num_ports(u32 psm)
{
	static const u8 bits[16] = { 0, 1, 1, 2, 1, 2, 2, 3,
				     1, 2, 2, 3, 2, 3, 3, 4 };

	return bits[psm & 0xf];
}

/**
 * init_luntable() - write an entry in the LUN table
 * @cfg:	Internal structure associated with the host.
 * @lli:	Per adapter LUN information structure.
 *
 * On successful return, a LUN table entry is created:
 *	- at the top for LUNs visible on multiple ports.
 *	- at the bottom for LUNs visible only on one port.
 *
 * Return: 0 on success, -errno on failure
 */
static int init_luntable(struct cxlflash_cfg *cfg, struct llun_info *lli)
{
	u32 chan;
	u32 lind;
	u32 nports;
	int rc = 0;
	int k;
	struct device *dev = &cfg->dev->dev;
	__be64 __iomem *fc_port_luns;

	mutex_lock(&global.mutex);

	if (lli->in_table)
		goto out;

	nports = get_num_ports(lli->port_sel);
	if (nports == 0 || nports > cfg->num_fc_ports) {
		WARN(1, "Unsupported port configuration nports=%u", nports);
		rc = -EIO;
		goto out;
	}

	if (nports > 1) {
		/*
		 * When LUN is visible from multiple ports, we will put
		 * it in the top half of the LUN table.
		 */
		for (k = 0; k < cfg->num_fc_ports; k++) {
			if (!(lli->port_sel & (1 << k)))
				continue;

			if (cfg->promote_lun_index == cfg->last_lun_index[k]) {
				rc = -ENOSPC;
				goto out;
			}
		}

		lind = lli->lun_index = cfg->promote_lun_index;
		dev_dbg(dev, "%s: Virtual LUNs on slot %d:\n", __func__, lind);

		for (k = 0; k < cfg->num_fc_ports; k++) {
			if (!(lli->port_sel & (1 << k)))
				continue;

			fc_port_luns = get_fc_port_luns(cfg, k);
			writeq_be(lli->lun_id[k], &fc_port_luns[lind]);
			dev_dbg(dev, "\t%d=%llx\n", k, lli->lun_id[k]);
		}

		cfg->promote_lun_index++;
	} else {
		/*
		 * When LUN is visible only from one port, we will put
		 * it in the bottom half of the LUN table.
		 */
		chan = PORTMASK2CHAN(lli->port_sel);
		if (cfg->promote_lun_index == cfg->last_lun_index[chan]) {
			rc = -ENOSPC;
			goto out;
		}

		lind = lli->lun_index = cfg->last_lun_index[chan];
		fc_port_luns = get_fc_port_luns(cfg, chan);
		writeq_be(lli->lun_id[chan], &fc_port_luns[lind]);
		cfg->last_lun_index[chan]--;
		dev_dbg(dev, "%s: Virtual LUNs on slot %d:\n\t%d=%llx\n",
			__func__, lind, chan, lli->lun_id[chan]);
	}

	lli->in_table = true;
out:
	mutex_unlock(&global.mutex);
	dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
	return rc;
}

/**
 * cxlflash_disk_virtual_open() - open a virtual disk of specified size
 * @sdev:	SCSI device associated with LUN owning virtual LUN.
 * @arg:	UVirtual ioctl data structure.
 *
 * On successful return, the user is informed of the resource handle
 * to be used to identify the virtual LUN and the size (in blocks) of
 * the virtual LUN in last LBA format. When the size of the virtual LUN
 * is zero, the last LBA is reflected as -1.
 *
 * Return: 0 on success, -errno on failure
 */
int cxlflash_disk_virtual_open(struct scsi_device *sdev, void *arg)
{
	struct cxlflash_cfg *cfg = shost_priv(sdev->host);
	struct device *dev = &cfg->dev->dev;
	struct llun_info *lli = sdev->hostdata;
	struct glun_info *gli = lli->parent;

	struct dk_cxlflash_uvirtual *virt = (struct dk_cxlflash_uvirtual *)arg;
	struct dk_cxlflash_resize resize;

	u64 ctxid = DECODE_CTXID(virt->context_id),
	    rctxid = virt->context_id;
	u64 lun_size = virt->lun_size;
	u64 last_lba = 0;
	u64 rsrc_handle = -1;

	int rc = 0;

	struct ctx_info *ctxi = NULL;
	struct sisl_rht_entry *rhte = NULL;

	dev_dbg(dev, "%s: ctxid=%llu ls=%llu\n", __func__, ctxid, lun_size);

	/* Setup the LUNs block allocator on first call */
	mutex_lock(&gli->mutex);
	if (gli->mode == MODE_NONE) {
		rc = init_vlun(lli);
		if (rc) {
			dev_err(dev, "%s: init_vlun failed rc=%d\n",
				__func__, rc);
			rc = -ENOMEM;
			goto err0;
		}
	}

	rc = cxlflash_lun_attach(gli, MODE_VIRTUAL, true);
	if (unlikely(rc)) {
		dev_err(dev, "%s: Failed attach to LUN (VIRTUAL)\n", __func__);
		goto err0;
	}
	mutex_unlock(&gli->mutex);

	rc = init_luntable(cfg, lli);
	if (rc) {
		dev_err(dev, "%s: init_luntable failed rc=%d\n", __func__, rc);
		goto err1;
	}

	ctxi = get_context(cfg, rctxid, lli, 0);
	if (unlikely(!ctxi)) {
		dev_err(dev, "%s: Bad context ctxid=%llu\n", __func__, ctxid);
		rc = -EINVAL;
		goto err1;
	}

	rhte = rhte_checkout(ctxi, lli);
	if (unlikely(!rhte)) {
		dev_err(dev, "%s: too many opens ctxid=%llu\n",
			__func__, ctxid);
		rc = -EMFILE;	/* too many opens  */
		goto err1;
	}

	rsrc_handle = (rhte - ctxi->rht_start);

	/* Populate RHT format 0 */
	rhte->nmask = MC_RHT_NMASK;
	rhte->fp = SISL_RHT_FP(0U, ctxi->rht_perms);

	/* Resize even if requested size is 0 */
	marshal_virt_to_resize(virt, &resize);
	resize.rsrc_handle = rsrc_handle;
	rc = _cxlflash_vlun_resize(sdev, ctxi, &resize);
	if (rc) {
		dev_err(dev, "%s: resize failed rc=%d\n", __func__, rc);
		goto err2;
	}
	last_lba = resize.last_lba;

	if (virt->hdr.flags & DK_CXLFLASH_UVIRTUAL_NEED_WRITE_SAME)
		ctxi->rht_needs_ws[rsrc_handle] = true;

	virt->hdr.return_flags = 0;
	virt->last_lba = last_lba;
	virt->rsrc_handle = rsrc_handle;

	if (get_num_ports(lli->port_sel) > 1)
		virt->hdr.return_flags |= DK_CXLFLASH_ALL_PORTS_ACTIVE;
out:
	if (likely(ctxi))
		put_context(ctxi);
	dev_dbg(dev, "%s: returning handle=%llu rc=%d llba=%llu\n",
		__func__, rsrc_handle, rc, last_lba);
	return rc;

err2:
	rhte_checkin(ctxi, rhte);
err1:
	cxlflash_lun_detach(gli);
	goto out;
err0:
	/* Special common cleanup prior to successful LUN attach */
	cxlflash_ba_terminate(&gli->blka.ba_lun);
	mutex_unlock(&gli->mutex);
	goto out;
}

/**
 * clone_lxt() - copies translation tables from source to destination RHTE
 * @afu:	AFU associated with the host.
 * @blka:	Block allocator associated with LUN.
 * @ctxid:	Context ID of context owning the RHTE.
 * @rhndl:	Resource handle associated with the RHTE.
 * @rhte:	Destination resource handle entry (RHTE).
 * @rhte_src:	Source resource handle entry (RHTE).
 *
 * Return: 0 on success, -errno on failure
 */
static int clone_lxt(struct afu *afu,
		     struct blka *blka,
		     ctx_hndl_t ctxid,
		     res_hndl_t rhndl,
		     struct sisl_rht_entry *rhte,
		     struct sisl_rht_entry *rhte_src)
{
	struct cxlflash_cfg *cfg = afu->parent;
	struct device *dev = &cfg->dev->dev;
	struct sisl_lxt_entry *lxt = NULL;
	bool locked = false;
	u32 ngrps;
	u64 aun;		/* chunk# allocated by block allocator */
	int j;
	int i = 0;
	int rc = 0;

	ngrps = LXT_NUM_GROUPS(rhte_src->lxt_cnt);

	if (ngrps) {
		/* allocate new LXTs for clone */
		lxt = kzalloc((sizeof(*lxt) * LXT_GROUP_SIZE * ngrps),
				GFP_KERNEL);
		if (unlikely(!lxt)) {
			rc = -ENOMEM;
			goto out;
		}

		/* copy over */
		memcpy(lxt, rhte_src->lxt_start,
		       (sizeof(*lxt) * rhte_src->lxt_cnt));

		/* clone the LBAs in block allocator via ref_cnt, note that the
		 * block allocator mutex must be held until it is established
		 * that this routine will complete without the need for a
		 * cleanup.
		 */
		mutex_lock(&blka->mutex);
		locked = true;
		for (i = 0; i < rhte_src->lxt_cnt; i++) {
			aun = (lxt[i].rlba_base >> MC_CHUNK_SHIFT);
			if (ba_clone(&blka->ba_lun, aun) == -1ULL) {
				rc = -EIO;
				goto err;
			}
		}
	}

	/*
	 * The following sequence is prescribed in the SISlite spec
	 * for syncing up with the AFU when adding LXT entries.
	 */
	dma_wmb(); /* Make LXT updates are visible */

	rhte->lxt_start = lxt;
	dma_wmb(); /* Make RHT entry's LXT table update visible */

	rhte->lxt_cnt = rhte_src->lxt_cnt;
	dma_wmb(); /* Make RHT entry's LXT table size update visible */

	rc = cxlflash_afu_sync(afu, ctxid, rhndl, AFU_LW_SYNC);
	if (unlikely(rc)) {
		rc = -EAGAIN;
		goto err2;
	}

out:
	if (locked)
		mutex_unlock(&blka->mutex);
	dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
	return rc;
err2:
	/* Reset the RHTE */
	rhte->lxt_cnt = 0;
	dma_wmb();
	rhte->lxt_start = NULL;
	dma_wmb();
err:
	/* free the clones already made */
	for (j = 0; j < i; j++) {
		aun = (lxt[j].rlba_base >> MC_CHUNK_SHIFT);
		ba_free(&blka->ba_lun, aun);
	}
	kfree(lxt);
	goto out;
}

/**
 * cxlflash_disk_clone() - clone a context by making snapshot of another
 * @sdev:	SCSI device associated with LUN owning virtual LUN.
 * @clone:	Clone ioctl data structure.
 *
 * This routine effectively performs cxlflash_disk_open operation for each
 * in-use virtual resource in the source context. Note that the destination
 * context must be in pristine state and cannot have any resource handles
 * open at the time of the clone.
 *
 * Return: 0 on success, -errno on failure
 */
int cxlflash_disk_clone(struct scsi_device *sdev,
			struct dk_cxlflash_clone *clone)
{
	struct cxlflash_cfg *cfg = shost_priv(sdev->host);
	struct device *dev = &cfg->dev->dev;
	struct llun_info *lli = sdev->hostdata;
	struct glun_info *gli = lli->parent;
	struct blka *blka = &gli->blka;
	struct afu *afu = cfg->afu;
	struct dk_cxlflash_release release = { { 0 }, 0 };

	struct ctx_info *ctxi_src = NULL,
			*ctxi_dst = NULL;
	struct lun_access *lun_access_src, *lun_access_dst;
	u32 perms;
	u64 ctxid_src = DECODE_CTXID(clone->context_id_src),
	    ctxid_dst = DECODE_CTXID(clone->context_id_dst),
	    rctxid_src = clone->context_id_src,
	    rctxid_dst = clone->context_id_dst;
	int i, j;
	int rc = 0;
	bool found;
	LIST_HEAD(sidecar);

	dev_dbg(dev, "%s: ctxid_src=%llu ctxid_dst=%llu\n",
		__func__, ctxid_src, ctxid_dst);

	/* Do not clone yourself */
	if (unlikely(rctxid_src == rctxid_dst)) {
		rc = -EINVAL;
		goto out;
	}

	if (unlikely(gli->mode != MODE_VIRTUAL)) {
		rc = -EINVAL;
		dev_dbg(dev, "%s: Only supported on virtual LUNs mode=%u\n",
			__func__, gli->mode);
		goto out;
	}

	ctxi_src = get_context(cfg, rctxid_src, lli, CTX_CTRL_CLONE);
	ctxi_dst = get_context(cfg, rctxid_dst, lli, 0);
	if (unlikely(!ctxi_src || !ctxi_dst)) {
		dev_dbg(dev, "%s: Bad context ctxid_src=%llu ctxid_dst=%llu\n",
			__func__, ctxid_src, ctxid_dst);
		rc = -EINVAL;
		goto out;
	}

	/* Verify there is no open resource handle in the destination context */
	for (i = 0; i < MAX_RHT_PER_CONTEXT; i++)
		if (ctxi_dst->rht_start[i].nmask != 0) {
			rc = -EINVAL;
			goto out;
		}

	/* Clone LUN access list */
	list_for_each_entry(lun_access_src, &ctxi_src->luns, list) {
		found = false;
		list_for_each_entry(lun_access_dst, &ctxi_dst->luns, list)
			if (lun_access_dst->sdev == lun_access_src->sdev) {
				found = true;
				break;
			}

		if (!found) {
			lun_access_dst = kzalloc(sizeof(*lun_access_dst),
						 GFP_KERNEL);
			if (unlikely(!lun_access_dst)) {
				dev_err(dev, "%s: lun_access allocation fail\n",
					__func__);
				rc = -ENOMEM;
				goto out;
			}

			*lun_access_dst = *lun_access_src;
			list_add(&lun_access_dst->list, &sidecar);
		}
	}

	if (unlikely(!ctxi_src->rht_out)) {
		dev_dbg(dev, "%s: Nothing to clone\n", __func__);
		goto out_success;
	}

	/* User specified permission on attach */
	perms = ctxi_dst->rht_perms;

	/*
	 * Copy over checked-out RHT (and their associated LXT) entries by
	 * hand, stopping after we've copied all outstanding entries and
	 * cleaning up if the clone fails.
	 *
	 * Note: This loop is equivalent to performing cxlflash_disk_open and
	 * cxlflash_vlun_resize. As such, LUN accounting needs to be taken into
	 * account by attaching after each successful RHT entry clone. In the
	 * event that a clone failure is experienced, the LUN detach is handled
	 * via the cleanup performed by _cxlflash_disk_release.
	 */
	for (i = 0; i < MAX_RHT_PER_CONTEXT; i++) {
		if (ctxi_src->rht_out == ctxi_dst->rht_out)
			break;
		if (ctxi_src->rht_start[i].nmask == 0)
			continue;

		/* Consume a destination RHT entry */
		ctxi_dst->rht_out++;
		ctxi_dst->rht_start[i].nmask = ctxi_src->rht_start[i].nmask;
		ctxi_dst->rht_start[i].fp =
		    SISL_RHT_FP_CLONE(ctxi_src->rht_start[i].fp, perms);
		ctxi_dst->rht_lun[i] = ctxi_src->rht_lun[i];

		rc = clone_lxt(afu, blka, ctxid_dst, i,
			       &ctxi_dst->rht_start[i],
			       &ctxi_src->rht_start[i]);
		if (rc) {
			marshal_clone_to_rele(clone, &release);
			for (j = 0; j < i; j++) {
				release.rsrc_handle = j;
				_cxlflash_disk_release(sdev, ctxi_dst,
						       &release);
			}

			/* Put back the one we failed on */
			rhte_checkin(ctxi_dst, &ctxi_dst->rht_start[i]);
			goto err;
		}

		cxlflash_lun_attach(gli, gli->mode, false);
	}

out_success:
	list_splice(&sidecar, &ctxi_dst->luns);

	/* fall through */
out:
	if (ctxi_src)
		put_context(ctxi_src);
	if (ctxi_dst)
		put_context(ctxi_dst);
	dev_dbg(dev, "%s: returning rc=%d\n", __func__, rc);
	return rc;

err:
	list_for_each_entry_safe(lun_access_src, lun_access_dst, &sidecar, list)
		kfree(lun_access_src);
	goto out;
}