summaryrefslogtreecommitdiff
path: root/drivers/xen/xen-scsiback.c
blob: d3dcda3449892aadfc57b42c48daf48cb9b6d6ad (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
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
/*
 * Xen SCSI backend driver
 *
 * Copyright (c) 2008, FUJITSU Limited
 *
 * Based on the blkback driver code.
 * Adaption to kernel taget core infrastructure taken from vhost/scsi.c
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#define pr_fmt(fmt) "xen-pvscsi: " fmt

#include <linux/module.h>
#include <linux/utsname.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/gfp.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/configfs.h>

#include <generated/utsrelease.h>

#include <scsi/scsi_host.h> /* SG_ALL */

#include <target/target_core_base.h>
#include <target/target_core_fabric.h>

#include <asm/hypervisor.h>

#include <xen/xen.h>
#include <xen/balloon.h>
#include <xen/events.h>
#include <xen/xenbus.h>
#include <xen/grant_table.h>
#include <xen/page.h>

#include <xen/interface/grant_table.h>
#include <xen/interface/io/vscsiif.h>

#define VSCSI_VERSION	"v0.1"
#define VSCSI_NAMELEN	32

struct ids_tuple {
	unsigned int hst;		/* host    */
	unsigned int chn;		/* channel */
	unsigned int tgt;		/* target  */
	unsigned int lun;		/* LUN     */
};

struct v2p_entry {
	struct ids_tuple v;		/* translate from */
	struct scsiback_tpg *tpg;	/* translate to   */
	unsigned int lun;
	struct kref kref;
	struct list_head l;
};

struct vscsibk_info {
	struct xenbus_device *dev;

	domid_t domid;
	unsigned int irq;

	struct vscsiif_back_ring ring;

	spinlock_t ring_lock;
	atomic_t nr_unreplied_reqs;

	spinlock_t v2p_lock;
	struct list_head v2p_entry_lists;

	wait_queue_head_t waiting_to_free;

	struct gnttab_page_cache free_pages;
};

/* theoretical maximum of grants for one request */
#define VSCSI_MAX_GRANTS	(SG_ALL + VSCSIIF_SG_TABLESIZE)

/*
 * VSCSI_GRANT_BATCH is the maximum number of grants to be processed in one
 * call to map/unmap grants. Don't choose it too large, as there are arrays
 * with VSCSI_GRANT_BATCH elements allocated on the stack.
 */
#define VSCSI_GRANT_BATCH	16

struct vscsibk_pend {
	uint16_t rqid;

	uint8_t cmnd[VSCSIIF_MAX_COMMAND_SIZE];
	uint8_t cmd_len;

	uint8_t sc_data_direction;
	uint16_t n_sg;		/* real length of SG list */
	uint16_t n_grants;	/* SG pages and potentially SG list */
	uint32_t data_len;
	uint32_t result;

	struct vscsibk_info *info;
	struct v2p_entry *v2p;
	struct scatterlist *sgl;

	uint8_t sense_buffer[VSCSIIF_SENSE_BUFFERSIZE];

	grant_handle_t grant_handles[VSCSI_MAX_GRANTS];
	struct page *pages[VSCSI_MAX_GRANTS];

	struct se_cmd se_cmd;

	struct completion tmr_done;
};

#define VSCSI_DEFAULT_SESSION_TAGS	128

struct scsiback_nexus {
	/* Pointer to TCM session for I_T Nexus */
	struct se_session *tvn_se_sess;
};

struct scsiback_tport {
	/* SCSI protocol the tport is providing */
	u8 tport_proto_id;
	/* Binary World Wide unique Port Name for pvscsi Target port */
	u64 tport_wwpn;
	/* ASCII formatted WWPN for pvscsi Target port */
	char tport_name[VSCSI_NAMELEN];
	/* Returned by scsiback_make_tport() */
	struct se_wwn tport_wwn;
};

struct scsiback_tpg {
	/* scsiback port target portal group tag for TCM */
	u16 tport_tpgt;
	/* track number of TPG Port/Lun Links wrt explicit I_T Nexus shutdown */
	int tv_tpg_port_count;
	/* xen-pvscsi references to tpg_nexus, protected by tv_tpg_mutex */
	int tv_tpg_fe_count;
	/* list for scsiback_list */
	struct list_head tv_tpg_list;
	/* Used to protect access for tpg_nexus */
	struct mutex tv_tpg_mutex;
	/* Pointer to the TCM pvscsi I_T Nexus for this TPG endpoint */
	struct scsiback_nexus *tpg_nexus;
	/* Pointer back to scsiback_tport */
	struct scsiback_tport *tport;
	/* Returned by scsiback_make_tpg() */
	struct se_portal_group se_tpg;
	/* alias used in xenstore */
	char param_alias[VSCSI_NAMELEN];
	/* list of info structures related to this target portal group */
	struct list_head info_list;
};

#define SCSIBACK_INVALID_HANDLE (~0)

static bool log_print_stat;
module_param(log_print_stat, bool, 0644);

static int scsiback_max_buffer_pages = 1024;
module_param_named(max_buffer_pages, scsiback_max_buffer_pages, int, 0644);
MODULE_PARM_DESC(max_buffer_pages,
"Maximum number of free pages to keep in backend buffer");

/* Global spinlock to protect scsiback TPG list */
static DEFINE_MUTEX(scsiback_mutex);
static LIST_HEAD(scsiback_list);

static void scsiback_get(struct vscsibk_info *info)
{
	atomic_inc(&info->nr_unreplied_reqs);
}

static void scsiback_put(struct vscsibk_info *info)
{
	if (atomic_dec_and_test(&info->nr_unreplied_reqs))
		wake_up(&info->waiting_to_free);
}

static unsigned long vaddr_page(struct page *page)
{
	unsigned long pfn = page_to_pfn(page);

	return (unsigned long)pfn_to_kaddr(pfn);
}

static unsigned long vaddr(struct vscsibk_pend *req, int seg)
{
	return vaddr_page(req->pages[seg]);
}

static void scsiback_print_status(char *sense_buffer, int errors,
					struct vscsibk_pend *pending_req)
{
	struct scsiback_tpg *tpg = pending_req->v2p->tpg;

	pr_err("[%s:%d] cmnd[0]=%02x -> st=%02x msg=%02x host=%02x\n",
	       tpg->tport->tport_name, pending_req->v2p->lun,
	       pending_req->cmnd[0], errors & 0xff, COMMAND_COMPLETE,
	       host_byte(errors));
}

static void scsiback_fast_flush_area(struct vscsibk_pend *req)
{
	struct gnttab_unmap_grant_ref unmap[VSCSI_GRANT_BATCH];
	struct page *pages[VSCSI_GRANT_BATCH];
	unsigned int i, invcount = 0;
	grant_handle_t handle;
	int err;

	kfree(req->sgl);
	req->sgl = NULL;
	req->n_sg = 0;

	if (!req->n_grants)
		return;

	for (i = 0; i < req->n_grants; i++) {
		handle = req->grant_handles[i];
		if (handle == SCSIBACK_INVALID_HANDLE)
			continue;
		gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i),
				    GNTMAP_host_map, handle);
		req->grant_handles[i] = SCSIBACK_INVALID_HANDLE;
		pages[invcount] = req->pages[i];
		put_page(pages[invcount]);
		invcount++;
		if (invcount < VSCSI_GRANT_BATCH)
			continue;
		err = gnttab_unmap_refs(unmap, NULL, pages, invcount);
		BUG_ON(err);
		invcount = 0;
	}

	if (invcount) {
		err = gnttab_unmap_refs(unmap, NULL, pages, invcount);
		BUG_ON(err);
	}

	gnttab_page_cache_put(&req->info->free_pages, req->pages,
			      req->n_grants);
	req->n_grants = 0;
}

static void scsiback_free_translation_entry(struct kref *kref)
{
	struct v2p_entry *entry = container_of(kref, struct v2p_entry, kref);
	struct scsiback_tpg *tpg = entry->tpg;

	mutex_lock(&tpg->tv_tpg_mutex);
	tpg->tv_tpg_fe_count--;
	mutex_unlock(&tpg->tv_tpg_mutex);

	kfree(entry);
}

static int32_t scsiback_result(int32_t result)
{
	int32_t host_status;

	switch (XEN_VSCSIIF_RSLT_HOST(result)) {
	case DID_OK:
		host_status = XEN_VSCSIIF_RSLT_HOST_OK;
		break;
	case DID_NO_CONNECT:
		host_status = XEN_VSCSIIF_RSLT_HOST_NO_CONNECT;
		break;
	case DID_BUS_BUSY:
		host_status = XEN_VSCSIIF_RSLT_HOST_BUS_BUSY;
		break;
	case DID_TIME_OUT:
		host_status = XEN_VSCSIIF_RSLT_HOST_TIME_OUT;
		break;
	case DID_BAD_TARGET:
		host_status = XEN_VSCSIIF_RSLT_HOST_BAD_TARGET;
		break;
	case DID_ABORT:
		host_status = XEN_VSCSIIF_RSLT_HOST_ABORT;
		break;
	case DID_PARITY:
		host_status = XEN_VSCSIIF_RSLT_HOST_PARITY;
		break;
	case DID_ERROR:
		host_status = XEN_VSCSIIF_RSLT_HOST_ERROR;
		break;
	case DID_RESET:
		host_status = XEN_VSCSIIF_RSLT_HOST_RESET;
		break;
	case DID_BAD_INTR:
		host_status = XEN_VSCSIIF_RSLT_HOST_BAD_INTR;
		break;
	case DID_PASSTHROUGH:
		host_status = XEN_VSCSIIF_RSLT_HOST_PASSTHROUGH;
		break;
	case DID_SOFT_ERROR:
		host_status = XEN_VSCSIIF_RSLT_HOST_SOFT_ERROR;
		break;
	case DID_IMM_RETRY:
		host_status = XEN_VSCSIIF_RSLT_HOST_IMM_RETRY;
		break;
	case DID_REQUEUE:
		host_status = XEN_VSCSIIF_RSLT_HOST_REQUEUE;
		break;
	case DID_TRANSPORT_DISRUPTED:
		host_status = XEN_VSCSIIF_RSLT_HOST_TRANSPORT_DISRUPTED;
		break;
	case DID_TRANSPORT_FAILFAST:
		host_status = XEN_VSCSIIF_RSLT_HOST_TRANSPORT_FAILFAST;
		break;
	case DID_TARGET_FAILURE:
		host_status = XEN_VSCSIIF_RSLT_HOST_TARGET_FAILURE;
		break;
	case DID_NEXUS_FAILURE:
		host_status = XEN_VSCSIIF_RSLT_HOST_NEXUS_FAILURE;
		break;
	case DID_ALLOC_FAILURE:
		host_status = XEN_VSCSIIF_RSLT_HOST_ALLOC_FAILURE;
		break;
	case DID_MEDIUM_ERROR:
		host_status = XEN_VSCSIIF_RSLT_HOST_MEDIUM_ERROR;
		break;
	case DID_TRANSPORT_MARGINAL:
		host_status = XEN_VSCSIIF_RSLT_HOST_TRANSPORT_MARGINAL;
		break;
	default:
		host_status = XEN_VSCSIIF_RSLT_HOST_ERROR;
		break;
	}

	return (host_status << 16) | (result & 0x00ffff);
}

static void scsiback_send_response(struct vscsibk_info *info,
			char *sense_buffer, int32_t result, uint32_t resid,
			uint16_t rqid)
{
	struct vscsiif_response *ring_res;
	int notify;
	struct scsi_sense_hdr sshdr;
	unsigned long flags;
	unsigned len;

	spin_lock_irqsave(&info->ring_lock, flags);

	ring_res = RING_GET_RESPONSE(&info->ring, info->ring.rsp_prod_pvt);
	info->ring.rsp_prod_pvt++;

	ring_res->rslt   = scsiback_result(result);
	ring_res->rqid   = rqid;

	if (sense_buffer != NULL &&
	    scsi_normalize_sense(sense_buffer, VSCSIIF_SENSE_BUFFERSIZE,
				 &sshdr)) {
		len = min_t(unsigned, 8 + sense_buffer[7],
			    VSCSIIF_SENSE_BUFFERSIZE);
		memcpy(ring_res->sense_buffer, sense_buffer, len);
		ring_res->sense_len = len;
	} else {
		ring_res->sense_len = 0;
	}

	ring_res->residual_len = resid;

	RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&info->ring, notify);
	spin_unlock_irqrestore(&info->ring_lock, flags);

	if (notify)
		notify_remote_via_irq(info->irq);
}

static void scsiback_do_resp_with_sense(char *sense_buffer, int32_t result,
			uint32_t resid, struct vscsibk_pend *pending_req)
{
	scsiback_send_response(pending_req->info, sense_buffer, result,
			       resid, pending_req->rqid);

	if (pending_req->v2p)
		kref_put(&pending_req->v2p->kref,
			 scsiback_free_translation_entry);
}

static void scsiback_cmd_done(struct vscsibk_pend *pending_req)
{
	struct vscsibk_info *info = pending_req->info;
	unsigned char *sense_buffer;
	unsigned int resid;
	int errors;

	sense_buffer = pending_req->sense_buffer;
	resid        = pending_req->se_cmd.residual_count;
	errors       = pending_req->result;

	if (errors && log_print_stat)
		scsiback_print_status(sense_buffer, errors, pending_req);

	scsiback_fast_flush_area(pending_req);
	scsiback_do_resp_with_sense(sense_buffer, errors, resid, pending_req);
	scsiback_put(info);
	/*
	 * Drop the extra KREF_ACK reference taken by target_submit_cmd_map_sgls()
	 * ahead of scsiback_check_stop_free() ->  transport_generic_free_cmd()
	 * final se_cmd->cmd_kref put.
	 */
	target_put_sess_cmd(&pending_req->se_cmd);
}

static void scsiback_cmd_exec(struct vscsibk_pend *pending_req)
{
	struct se_cmd *se_cmd = &pending_req->se_cmd;
	struct se_session *sess = pending_req->v2p->tpg->tpg_nexus->tvn_se_sess;

	scsiback_get(pending_req->info);
	se_cmd->tag = pending_req->rqid;
	target_init_cmd(se_cmd, sess, pending_req->sense_buffer,
			pending_req->v2p->lun, pending_req->data_len, 0,
			pending_req->sc_data_direction, TARGET_SCF_ACK_KREF);

	if (target_submit_prep(se_cmd, pending_req->cmnd, pending_req->sgl,
			       pending_req->n_sg, NULL, 0, NULL, 0, GFP_KERNEL))
		return;

	target_submit(se_cmd);
}

static int scsiback_gnttab_data_map_batch(struct gnttab_map_grant_ref *map,
	struct page **pg, grant_handle_t *grant, int cnt)
{
	int err, i;

	if (!cnt)
		return 0;

	err = gnttab_map_refs(map, NULL, pg, cnt);
	for (i = 0; i < cnt; i++) {
		if (unlikely(map[i].status != GNTST_okay)) {
			pr_err("invalid buffer -- could not remap it\n");
			map[i].handle = SCSIBACK_INVALID_HANDLE;
			if (!err)
				err = -ENOMEM;
		} else {
			get_page(pg[i]);
		}
		grant[i] = map[i].handle;
	}
	return err;
}

static int scsiback_gnttab_data_map_list(struct vscsibk_pend *pending_req,
			struct scsiif_request_segment *seg, struct page **pg,
			grant_handle_t *grant, int cnt, u32 flags)
{
	int mapcount = 0, i, err = 0;
	struct gnttab_map_grant_ref map[VSCSI_GRANT_BATCH];
	struct vscsibk_info *info = pending_req->info;

	for (i = 0; i < cnt; i++) {
		if (gnttab_page_cache_get(&info->free_pages, pg + mapcount)) {
			gnttab_page_cache_put(&info->free_pages, pg, mapcount);
			pr_err("no grant page\n");
			return -ENOMEM;
		}
		gnttab_set_map_op(&map[mapcount], vaddr_page(pg[mapcount]),
				  flags, seg[i].gref, info->domid);
		mapcount++;
		if (mapcount < VSCSI_GRANT_BATCH)
			continue;
		err = scsiback_gnttab_data_map_batch(map, pg, grant, mapcount);
		pg += mapcount;
		grant += mapcount;
		pending_req->n_grants += mapcount;
		if (err)
			return err;
		mapcount = 0;
	}
	err = scsiback_gnttab_data_map_batch(map, pg, grant, mapcount);
	pending_req->n_grants += mapcount;
	return err;
}

static int scsiback_gnttab_data_map(struct vscsiif_request *ring_req,
					struct vscsibk_pend *pending_req)
{
	u32 flags;
	int i, err, n_segs, i_seg = 0;
	struct page **pg;
	struct scsiif_request_segment *seg;
	unsigned long end_seg = 0;
	unsigned int nr_segments = (unsigned int)ring_req->nr_segments;
	unsigned int nr_sgl = 0;
	struct scatterlist *sg;
	grant_handle_t *grant;

	pending_req->n_sg = 0;
	pending_req->n_grants = 0;
	pending_req->data_len = 0;

	nr_segments &= ~VSCSIIF_SG_GRANT;
	if (!nr_segments)
		return 0;

	if (nr_segments > VSCSIIF_SG_TABLESIZE) {
		pr_debug("invalid parameter nr_seg = %d\n",
			ring_req->nr_segments);
		return -EINVAL;
	}

	if (ring_req->nr_segments & VSCSIIF_SG_GRANT) {
		err = scsiback_gnttab_data_map_list(pending_req, ring_req->seg,
			pending_req->pages, pending_req->grant_handles,
			nr_segments, GNTMAP_host_map | GNTMAP_readonly);
		if (err)
			return err;
		nr_sgl = nr_segments;
		nr_segments = 0;
		for (i = 0; i < nr_sgl; i++) {
			n_segs = ring_req->seg[i].length /
				 sizeof(struct scsiif_request_segment);
			if ((unsigned)ring_req->seg[i].offset +
			    (unsigned)ring_req->seg[i].length > PAGE_SIZE ||
			    n_segs * sizeof(struct scsiif_request_segment) !=
			    ring_req->seg[i].length)
				return -EINVAL;
			nr_segments += n_segs;
		}
		if (nr_segments > SG_ALL) {
			pr_debug("invalid nr_seg = %d\n", nr_segments);
			return -EINVAL;
		}
	}

	/* free of (sgl) in fast_flush_area() */
	pending_req->sgl = kmalloc_array(nr_segments,
					sizeof(struct scatterlist), GFP_KERNEL);
	if (!pending_req->sgl)
		return -ENOMEM;

	sg_init_table(pending_req->sgl, nr_segments);
	pending_req->n_sg = nr_segments;

	flags = GNTMAP_host_map;
	if (pending_req->sc_data_direction == DMA_TO_DEVICE)
		flags |= GNTMAP_readonly;

	pg = pending_req->pages + nr_sgl;
	grant = pending_req->grant_handles + nr_sgl;
	if (!nr_sgl) {
		seg = ring_req->seg;
		err = scsiback_gnttab_data_map_list(pending_req, seg,
			pg, grant, nr_segments, flags);
		if (err)
			return err;
	} else {
		for (i = 0; i < nr_sgl; i++) {
			seg = (struct scsiif_request_segment *)(
			      vaddr(pending_req, i) + ring_req->seg[i].offset);
			n_segs = ring_req->seg[i].length /
				 sizeof(struct scsiif_request_segment);
			err = scsiback_gnttab_data_map_list(pending_req, seg,
				pg, grant, n_segs, flags);
			if (err)
				return err;
			pg += n_segs;
			grant += n_segs;
		}
		end_seg = vaddr(pending_req, 0) + ring_req->seg[0].offset;
		seg = (struct scsiif_request_segment *)end_seg;
		end_seg += ring_req->seg[0].length;
		pg = pending_req->pages + nr_sgl;
	}

	for_each_sg(pending_req->sgl, sg, nr_segments, i) {
		sg_set_page(sg, pg[i], seg->length, seg->offset);
		pending_req->data_len += seg->length;
		seg++;
		if (nr_sgl && (unsigned long)seg >= end_seg) {
			i_seg++;
			end_seg = vaddr(pending_req, i_seg) +
				  ring_req->seg[i_seg].offset;
			seg = (struct scsiif_request_segment *)end_seg;
			end_seg += ring_req->seg[i_seg].length;
		}
		if (sg->offset >= PAGE_SIZE ||
		    sg->length > PAGE_SIZE ||
		    sg->offset + sg->length > PAGE_SIZE)
			return -EINVAL;
	}

	return 0;
}

static void scsiback_disconnect(struct vscsibk_info *info)
{
	wait_event(info->waiting_to_free,
		atomic_read(&info->nr_unreplied_reqs) == 0);

	unbind_from_irqhandler(info->irq, info);
	info->irq = 0;
	xenbus_unmap_ring_vfree(info->dev, info->ring.sring);
}

static void scsiback_device_action(struct vscsibk_pend *pending_req,
	enum tcm_tmreq_table act, int tag)
{
	struct scsiback_tpg *tpg = pending_req->v2p->tpg;
	struct scsiback_nexus *nexus = tpg->tpg_nexus;
	struct se_cmd *se_cmd = &pending_req->se_cmd;
	u64 unpacked_lun = pending_req->v2p->lun;
	int rc, err = XEN_VSCSIIF_RSLT_RESET_FAILED;

	init_completion(&pending_req->tmr_done);

	rc = target_submit_tmr(&pending_req->se_cmd, nexus->tvn_se_sess,
			       &pending_req->sense_buffer[0],
			       unpacked_lun, NULL, act, GFP_KERNEL,
			       tag, TARGET_SCF_ACK_KREF);
	if (rc)
		goto err;

	wait_for_completion(&pending_req->tmr_done);

	err = (se_cmd->se_tmr_req->response == TMR_FUNCTION_COMPLETE) ?
		XEN_VSCSIIF_RSLT_RESET_SUCCESS : XEN_VSCSIIF_RSLT_RESET_FAILED;

	scsiback_do_resp_with_sense(NULL, err, 0, pending_req);
	transport_generic_free_cmd(&pending_req->se_cmd, 0);
	return;

err:
	scsiback_do_resp_with_sense(NULL, err, 0, pending_req);
}

/*
  Perform virtual to physical translation
*/
static struct v2p_entry *scsiback_do_translation(struct vscsibk_info *info,
			struct ids_tuple *v)
{
	struct v2p_entry *entry;
	struct list_head *head = &(info->v2p_entry_lists);
	unsigned long flags;

	spin_lock_irqsave(&info->v2p_lock, flags);
	list_for_each_entry(entry, head, l) {
		if ((entry->v.chn == v->chn) &&
		    (entry->v.tgt == v->tgt) &&
		    (entry->v.lun == v->lun)) {
			kref_get(&entry->kref);
			goto out;
		}
	}
	entry = NULL;

out:
	spin_unlock_irqrestore(&info->v2p_lock, flags);
	return entry;
}

static struct vscsibk_pend *scsiback_get_pend_req(struct vscsiif_back_ring *ring,
				struct v2p_entry *v2p)
{
	struct scsiback_tpg *tpg = v2p->tpg;
	struct scsiback_nexus *nexus = tpg->tpg_nexus;
	struct se_session *se_sess = nexus->tvn_se_sess;
	struct vscsibk_pend *req;
	int tag, cpu, i;

	tag = sbitmap_queue_get(&se_sess->sess_tag_pool, &cpu);
	if (tag < 0) {
		pr_err("Unable to obtain tag for vscsiif_request\n");
		return ERR_PTR(-ENOMEM);
	}

	req = &((struct vscsibk_pend *)se_sess->sess_cmd_map)[tag];
	memset(req, 0, sizeof(*req));
	req->se_cmd.map_tag = tag;
	req->se_cmd.map_cpu = cpu;

	for (i = 0; i < VSCSI_MAX_GRANTS; i++)
		req->grant_handles[i] = SCSIBACK_INVALID_HANDLE;

	return req;
}

static struct vscsibk_pend *prepare_pending_reqs(struct vscsibk_info *info,
				struct vscsiif_back_ring *ring,
				struct vscsiif_request *ring_req)
{
	struct vscsibk_pend *pending_req;
	struct v2p_entry *v2p;
	struct ids_tuple vir;

	/* request range check from frontend */
	if ((ring_req->sc_data_direction != DMA_BIDIRECTIONAL) &&
		(ring_req->sc_data_direction != DMA_TO_DEVICE) &&
		(ring_req->sc_data_direction != DMA_FROM_DEVICE) &&
		(ring_req->sc_data_direction != DMA_NONE)) {
		pr_debug("invalid parameter data_dir = %d\n",
			ring_req->sc_data_direction);
		return ERR_PTR(-EINVAL);
	}
	if (ring_req->cmd_len > VSCSIIF_MAX_COMMAND_SIZE) {
		pr_debug("invalid parameter cmd_len = %d\n",
			ring_req->cmd_len);
		return ERR_PTR(-EINVAL);
	}

	vir.chn = ring_req->channel;
	vir.tgt = ring_req->id;
	vir.lun = ring_req->lun;

	v2p = scsiback_do_translation(info, &vir);
	if (!v2p) {
		pr_debug("the v2p of (chn:%d, tgt:%d, lun:%d) doesn't exist.\n",
			 vir.chn, vir.tgt, vir.lun);
		return ERR_PTR(-ENODEV);
	}

	pending_req = scsiback_get_pend_req(ring, v2p);
	if (IS_ERR(pending_req)) {
		kref_put(&v2p->kref, scsiback_free_translation_entry);
		return ERR_PTR(-ENOMEM);
	}
	pending_req->rqid = ring_req->rqid;
	pending_req->info = info;
	pending_req->v2p = v2p;
	pending_req->sc_data_direction = ring_req->sc_data_direction;
	pending_req->cmd_len = ring_req->cmd_len;
	memcpy(pending_req->cmnd, ring_req->cmnd, pending_req->cmd_len);

	return pending_req;
}

static int scsiback_do_cmd_fn(struct vscsibk_info *info,
			      unsigned int *eoi_flags)
{
	struct vscsiif_back_ring *ring = &info->ring;
	struct vscsiif_request ring_req;
	struct vscsibk_pend *pending_req;
	RING_IDX rc, rp;
	int more_to_do;
	uint32_t result;

	rc = ring->req_cons;
	rp = ring->sring->req_prod;
	rmb();	/* guest system is accessing ring, too */

	if (RING_REQUEST_PROD_OVERFLOW(ring, rp)) {
		rc = ring->rsp_prod_pvt;
		pr_warn("Dom%d provided bogus ring requests (%#x - %#x = %u). Halting ring processing\n",
			   info->domid, rp, rc, rp - rc);
		return -EINVAL;
	}

	while ((rc != rp)) {
		*eoi_flags &= ~XEN_EOI_FLAG_SPURIOUS;

		if (RING_REQUEST_CONS_OVERFLOW(ring, rc))
			break;

		RING_COPY_REQUEST(ring, rc, &ring_req);
		ring->req_cons = ++rc;

		pending_req = prepare_pending_reqs(info, ring, &ring_req);
		if (IS_ERR(pending_req)) {
			switch (PTR_ERR(pending_req)) {
			case -ENODEV:
				result = DID_NO_CONNECT;
				break;
			default:
				result = DID_ERROR;
				break;
			}
			scsiback_send_response(info, NULL, result << 16, 0,
					       ring_req.rqid);
			return 1;
		}

		switch (ring_req.act) {
		case VSCSIIF_ACT_SCSI_CDB:
			if (scsiback_gnttab_data_map(&ring_req, pending_req)) {
				scsiback_fast_flush_area(pending_req);
				scsiback_do_resp_with_sense(NULL,
						DID_ERROR << 16, 0, pending_req);
				transport_generic_free_cmd(&pending_req->se_cmd, 0);
			} else {
				scsiback_cmd_exec(pending_req);
			}
			break;
		case VSCSIIF_ACT_SCSI_ABORT:
			scsiback_device_action(pending_req, TMR_ABORT_TASK,
				ring_req.ref_rqid);
			break;
		case VSCSIIF_ACT_SCSI_RESET:
			scsiback_device_action(pending_req, TMR_LUN_RESET, 0);
			break;
		default:
			pr_err_ratelimited("invalid request\n");
			scsiback_do_resp_with_sense(NULL, DID_ERROR << 16, 0,
						    pending_req);
			transport_generic_free_cmd(&pending_req->se_cmd, 0);
			break;
		}

		/* Yield point for this unbounded loop. */
		cond_resched();
	}

	gnttab_page_cache_shrink(&info->free_pages, scsiback_max_buffer_pages);

	RING_FINAL_CHECK_FOR_REQUESTS(&info->ring, more_to_do);
	return more_to_do;
}

static irqreturn_t scsiback_irq_fn(int irq, void *dev_id)
{
	struct vscsibk_info *info = dev_id;
	int rc;
	unsigned int eoi_flags = XEN_EOI_FLAG_SPURIOUS;

	while ((rc = scsiback_do_cmd_fn(info, &eoi_flags)) > 0)
		cond_resched();

	/* In case of a ring error we keep the event channel masked. */
	if (!rc)
		xen_irq_lateeoi(irq, eoi_flags);

	return IRQ_HANDLED;
}

static int scsiback_init_sring(struct vscsibk_info *info, grant_ref_t ring_ref,
			evtchn_port_t evtchn)
{
	void *area;
	struct vscsiif_sring *sring;
	int err;

	if (info->irq)
		return -1;

	err = xenbus_map_ring_valloc(info->dev, &ring_ref, 1, &area);
	if (err)
		return err;

	sring = (struct vscsiif_sring *)area;
	BACK_RING_INIT(&info->ring, sring, PAGE_SIZE);

	err = bind_interdomain_evtchn_to_irq_lateeoi(info->dev, evtchn);
	if (err < 0)
		goto unmap_page;

	info->irq = err;

	err = request_threaded_irq(info->irq, NULL, scsiback_irq_fn,
				   IRQF_ONESHOT, "vscsiif-backend", info);
	if (err)
		goto free_irq;

	return 0;

free_irq:
	unbind_from_irqhandler(info->irq, info);
	info->irq = 0;
unmap_page:
	xenbus_unmap_ring_vfree(info->dev, area);

	return err;
}

static int scsiback_map(struct vscsibk_info *info)
{
	struct xenbus_device *dev = info->dev;
	unsigned int ring_ref;
	evtchn_port_t evtchn;
	int err;

	err = xenbus_gather(XBT_NIL, dev->otherend,
			"ring-ref", "%u", &ring_ref,
			"event-channel", "%u", &evtchn, NULL);
	if (err) {
		xenbus_dev_fatal(dev, err, "reading %s ring", dev->otherend);
		return err;
	}

	return scsiback_init_sring(info, ring_ref, evtchn);
}

/*
  Check for a translation entry being present
*/
static struct v2p_entry *scsiback_chk_translation_entry(
	struct vscsibk_info *info, struct ids_tuple *v)
{
	struct list_head *head = &(info->v2p_entry_lists);
	struct v2p_entry *entry;

	list_for_each_entry(entry, head, l)
		if ((entry->v.chn == v->chn) &&
		    (entry->v.tgt == v->tgt) &&
		    (entry->v.lun == v->lun))
			return entry;

	return NULL;
}

/*
  Add a new translation entry
*/
static int scsiback_add_translation_entry(struct vscsibk_info *info,
					  char *phy, struct ids_tuple *v)
{
	int err = 0;
	struct v2p_entry *new;
	unsigned long flags;
	char *lunp;
	unsigned long long unpacked_lun;
	struct se_lun *se_lun;
	struct scsiback_tpg *tpg_entry, *tpg = NULL;
	char *error = "doesn't exist";

	lunp = strrchr(phy, ':');
	if (!lunp) {
		pr_err("illegal format of physical device %s\n", phy);
		return -EINVAL;
	}
	*lunp = 0;
	lunp++;
	err = kstrtoull(lunp, 10, &unpacked_lun);
	if (err < 0) {
		pr_err("lun number not valid: %s\n", lunp);
		return err;
	}

	mutex_lock(&scsiback_mutex);
	list_for_each_entry(tpg_entry, &scsiback_list, tv_tpg_list) {
		if (!strcmp(phy, tpg_entry->tport->tport_name) ||
		    !strcmp(phy, tpg_entry->param_alias)) {
			mutex_lock(&tpg_entry->se_tpg.tpg_lun_mutex);
			hlist_for_each_entry(se_lun, &tpg_entry->se_tpg.tpg_lun_hlist, link) {
				if (se_lun->unpacked_lun == unpacked_lun) {
					if (!tpg_entry->tpg_nexus)
						error = "nexus undefined";
					else
						tpg = tpg_entry;
					break;
				}
			}
			mutex_unlock(&tpg_entry->se_tpg.tpg_lun_mutex);
			break;
		}
	}
	if (tpg) {
		mutex_lock(&tpg->tv_tpg_mutex);
		tpg->tv_tpg_fe_count++;
		mutex_unlock(&tpg->tv_tpg_mutex);
	}
	mutex_unlock(&scsiback_mutex);

	if (!tpg) {
		pr_err("%s:%llu %s\n", phy, unpacked_lun, error);
		return -ENODEV;
	}

	new = kmalloc(sizeof(struct v2p_entry), GFP_KERNEL);
	if (new == NULL) {
		err = -ENOMEM;
		goto out_free;
	}

	spin_lock_irqsave(&info->v2p_lock, flags);

	/* Check double assignment to identical virtual ID */
	if (scsiback_chk_translation_entry(info, v)) {
		pr_warn("Virtual ID is already used. Assignment was not performed.\n");
		err = -EEXIST;
		goto out;
	}

	/* Create a new translation entry and add to the list */
	kref_init(&new->kref);
	new->v = *v;
	new->tpg = tpg;
	new->lun = unpacked_lun;
	list_add_tail(&new->l, &info->v2p_entry_lists);

out:
	spin_unlock_irqrestore(&info->v2p_lock, flags);

out_free:
	if (err) {
		mutex_lock(&tpg->tv_tpg_mutex);
		tpg->tv_tpg_fe_count--;
		mutex_unlock(&tpg->tv_tpg_mutex);
		kfree(new);
	}

	return err;
}

static void __scsiback_del_translation_entry(struct v2p_entry *entry)
{
	list_del(&entry->l);
	kref_put(&entry->kref, scsiback_free_translation_entry);
}

/*
  Delete the translation entry specified
*/
static int scsiback_del_translation_entry(struct vscsibk_info *info,
					  struct ids_tuple *v)
{
	struct v2p_entry *entry;
	unsigned long flags;
	int ret = 0;

	spin_lock_irqsave(&info->v2p_lock, flags);
	/* Find out the translation entry specified */
	entry = scsiback_chk_translation_entry(info, v);
	if (entry)
		__scsiback_del_translation_entry(entry);
	else
		ret = -ENOENT;

	spin_unlock_irqrestore(&info->v2p_lock, flags);
	return ret;
}

static void scsiback_do_add_lun(struct vscsibk_info *info, const char *state,
				char *phy, struct ids_tuple *vir, int try)
{
	struct v2p_entry *entry;
	unsigned long flags;
	int err;

	if (try) {
		spin_lock_irqsave(&info->v2p_lock, flags);
		entry = scsiback_chk_translation_entry(info, vir);
		spin_unlock_irqrestore(&info->v2p_lock, flags);
		if (entry)
			return;
	}
	if (!scsiback_add_translation_entry(info, phy, vir)) {
		if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
				  "%d", XenbusStateInitialised)) {
			pr_err("xenbus_printf error %s\n", state);
			scsiback_del_translation_entry(info, vir);
		}
	} else if (!try) {
		err = xenbus_printf(XBT_NIL, info->dev->nodename, state,
			      "%d", XenbusStateClosed);
		if (err)
			xenbus_dev_error(info->dev, err,
				"%s: writing %s", __func__, state);
	}
}

static void scsiback_do_del_lun(struct vscsibk_info *info, const char *state,
				struct ids_tuple *vir)
{
	if (!scsiback_del_translation_entry(info, vir)) {
		if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
				  "%d", XenbusStateClosed))
			pr_err("xenbus_printf error %s\n", state);
	}
}

#define VSCSIBACK_OP_ADD_OR_DEL_LUN	1
#define VSCSIBACK_OP_UPDATEDEV_STATE	2

static void scsiback_do_1lun_hotplug(struct vscsibk_info *info, int op,
				     char *ent)
{
	int err;
	struct ids_tuple vir;
	char *val;
	int device_state;
	char phy[VSCSI_NAMELEN];
	char str[64];
	char state[64];
	struct xenbus_device *dev = info->dev;

	/* read status */
	snprintf(state, sizeof(state), "vscsi-devs/%s/state", ent);
	err = xenbus_scanf(XBT_NIL, dev->nodename, state, "%u", &device_state);
	if (XENBUS_EXIST_ERR(err))
		return;

	/* physical SCSI device */
	snprintf(str, sizeof(str), "vscsi-devs/%s/p-dev", ent);
	val = xenbus_read(XBT_NIL, dev->nodename, str, NULL);
	if (IS_ERR(val)) {
		err = xenbus_printf(XBT_NIL, dev->nodename, state,
			      "%d", XenbusStateClosed);
		if (err)
			xenbus_dev_error(info->dev, err,
				"%s: writing %s", __func__, state);
		return;
	}
	strscpy(phy, val, VSCSI_NAMELEN);
	kfree(val);

	/* virtual SCSI device */
	snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", ent);
	err = xenbus_scanf(XBT_NIL, dev->nodename, str, "%u:%u:%u:%u",
			   &vir.hst, &vir.chn, &vir.tgt, &vir.lun);
	if (XENBUS_EXIST_ERR(err)) {
		err = xenbus_printf(XBT_NIL, dev->nodename, state,
			      "%d", XenbusStateClosed);
		if (err)
			xenbus_dev_error(info->dev, err,
				"%s: writing %s", __func__, state);
		return;
	}

	switch (op) {
	case VSCSIBACK_OP_ADD_OR_DEL_LUN:
		switch (device_state) {
		case XenbusStateInitialising:
			scsiback_do_add_lun(info, state, phy, &vir, 0);
			break;
		case XenbusStateConnected:
			scsiback_do_add_lun(info, state, phy, &vir, 1);
			break;
		case XenbusStateClosing:
			scsiback_do_del_lun(info, state, &vir);
			break;
		default:
			break;
		}
		break;

	case VSCSIBACK_OP_UPDATEDEV_STATE:
		if (device_state == XenbusStateInitialised) {
			/* modify vscsi-devs/dev-x/state */
			if (xenbus_printf(XBT_NIL, dev->nodename, state,
					  "%d", XenbusStateConnected)) {
				pr_err("xenbus_printf error %s\n", str);
				scsiback_del_translation_entry(info, &vir);
				xenbus_printf(XBT_NIL, dev->nodename, state,
					      "%d", XenbusStateClosed);
			}
		}
		break;
	/* When it is necessary, processing is added here. */
	default:
		break;
	}
}

static void scsiback_do_lun_hotplug(struct vscsibk_info *info, int op)
{
	int i;
	char **dir;
	unsigned int ndir = 0;

	dir = xenbus_directory(XBT_NIL, info->dev->nodename, "vscsi-devs",
			       &ndir);
	if (IS_ERR(dir))
		return;

	for (i = 0; i < ndir; i++)
		scsiback_do_1lun_hotplug(info, op, dir[i]);

	kfree(dir);
}

static void scsiback_frontend_changed(struct xenbus_device *dev,
					enum xenbus_state frontend_state)
{
	struct vscsibk_info *info = dev_get_drvdata(&dev->dev);

	switch (frontend_state) {
	case XenbusStateInitialising:
		break;

	case XenbusStateInitialised:
		if (scsiback_map(info))
			break;

		scsiback_do_lun_hotplug(info, VSCSIBACK_OP_ADD_OR_DEL_LUN);
		xenbus_switch_state(dev, XenbusStateConnected);
		break;

	case XenbusStateConnected:
		scsiback_do_lun_hotplug(info, VSCSIBACK_OP_UPDATEDEV_STATE);

		if (dev->state == XenbusStateConnected)
			break;

		xenbus_switch_state(dev, XenbusStateConnected);
		break;

	case XenbusStateClosing:
		if (info->irq)
			scsiback_disconnect(info);

		xenbus_switch_state(dev, XenbusStateClosing);
		break;

	case XenbusStateClosed:
		xenbus_switch_state(dev, XenbusStateClosed);
		if (xenbus_dev_is_online(dev))
			break;
		fallthrough;	/* if not online */
	case XenbusStateUnknown:
		device_unregister(&dev->dev);
		break;

	case XenbusStateReconfiguring:
		scsiback_do_lun_hotplug(info, VSCSIBACK_OP_ADD_OR_DEL_LUN);
		xenbus_switch_state(dev, XenbusStateReconfigured);

		break;

	default:
		xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
					frontend_state);
		break;
	}
}

/*
  Release the translation entry specfied
*/
static void scsiback_release_translation_entry(struct vscsibk_info *info)
{
	struct v2p_entry *entry, *tmp;
	struct list_head *head = &(info->v2p_entry_lists);
	unsigned long flags;

	spin_lock_irqsave(&info->v2p_lock, flags);

	list_for_each_entry_safe(entry, tmp, head, l)
		__scsiback_del_translation_entry(entry);

	spin_unlock_irqrestore(&info->v2p_lock, flags);
}

static int scsiback_remove(struct xenbus_device *dev)
{
	struct vscsibk_info *info = dev_get_drvdata(&dev->dev);

	if (info->irq)
		scsiback_disconnect(info);

	scsiback_release_translation_entry(info);

	gnttab_page_cache_shrink(&info->free_pages, 0);

	dev_set_drvdata(&dev->dev, NULL);

	return 0;
}

static int scsiback_probe(struct xenbus_device *dev,
			   const struct xenbus_device_id *id)
{
	int err;

	struct vscsibk_info *info = kzalloc(sizeof(struct vscsibk_info),
					    GFP_KERNEL);

	pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);

	if (!info) {
		xenbus_dev_fatal(dev, -ENOMEM, "allocating backend structure");
		return -ENOMEM;
	}
	info->dev = dev;
	dev_set_drvdata(&dev->dev, info);

	info->domid = dev->otherend_id;
	spin_lock_init(&info->ring_lock);
	atomic_set(&info->nr_unreplied_reqs, 0);
	init_waitqueue_head(&info->waiting_to_free);
	info->dev = dev;
	info->irq = 0;
	INIT_LIST_HEAD(&info->v2p_entry_lists);
	spin_lock_init(&info->v2p_lock);
	gnttab_page_cache_init(&info->free_pages);

	err = xenbus_printf(XBT_NIL, dev->nodename, "feature-sg-grant", "%u",
			    SG_ALL);
	if (err)
		xenbus_dev_error(dev, err, "writing feature-sg-grant");

	err = xenbus_switch_state(dev, XenbusStateInitWait);
	if (err)
		goto fail;

	return 0;

fail:
	pr_warn("%s failed\n", __func__);
	scsiback_remove(dev);

	return err;
}

static char *scsiback_dump_proto_id(struct scsiback_tport *tport)
{
	switch (tport->tport_proto_id) {
	case SCSI_PROTOCOL_SAS:
		return "SAS";
	case SCSI_PROTOCOL_FCP:
		return "FCP";
	case SCSI_PROTOCOL_ISCSI:
		return "iSCSI";
	default:
		break;
	}

	return "Unknown";
}

static char *scsiback_get_fabric_wwn(struct se_portal_group *se_tpg)
{
	struct scsiback_tpg *tpg = container_of(se_tpg,
				struct scsiback_tpg, se_tpg);
	struct scsiback_tport *tport = tpg->tport;

	return &tport->tport_name[0];
}

static u16 scsiback_get_tag(struct se_portal_group *se_tpg)
{
	struct scsiback_tpg *tpg = container_of(se_tpg,
				struct scsiback_tpg, se_tpg);
	return tpg->tport_tpgt;
}

static struct se_wwn *
scsiback_make_tport(struct target_fabric_configfs *tf,
		     struct config_group *group,
		     const char *name)
{
	struct scsiback_tport *tport;
	char *ptr;
	u64 wwpn = 0;
	int off = 0;

	tport = kzalloc(sizeof(struct scsiback_tport), GFP_KERNEL);
	if (!tport)
		return ERR_PTR(-ENOMEM);

	tport->tport_wwpn = wwpn;
	/*
	 * Determine the emulated Protocol Identifier and Target Port Name
	 * based on the incoming configfs directory name.
	 */
	ptr = strstr(name, "naa.");
	if (ptr) {
		tport->tport_proto_id = SCSI_PROTOCOL_SAS;
		goto check_len;
	}
	ptr = strstr(name, "fc.");
	if (ptr) {
		tport->tport_proto_id = SCSI_PROTOCOL_FCP;
		off = 3; /* Skip over "fc." */
		goto check_len;
	}
	ptr = strstr(name, "iqn.");
	if (ptr) {
		tport->tport_proto_id = SCSI_PROTOCOL_ISCSI;
		goto check_len;
	}

	pr_err("Unable to locate prefix for emulated Target Port: %s\n", name);
	kfree(tport);
	return ERR_PTR(-EINVAL);

check_len:
	if (strlen(name) >= VSCSI_NAMELEN) {
		pr_err("Emulated %s Address: %s, exceeds max: %d\n", name,
			scsiback_dump_proto_id(tport), VSCSI_NAMELEN);
		kfree(tport);
		return ERR_PTR(-EINVAL);
	}
	snprintf(&tport->tport_name[0], VSCSI_NAMELEN, "%s", &name[off]);

	pr_debug("Allocated emulated Target %s Address: %s\n",
		 scsiback_dump_proto_id(tport), name);

	return &tport->tport_wwn;
}

static void scsiback_drop_tport(struct se_wwn *wwn)
{
	struct scsiback_tport *tport = container_of(wwn,
				struct scsiback_tport, tport_wwn);

	pr_debug("Deallocating emulated Target %s Address: %s\n",
		 scsiback_dump_proto_id(tport), tport->tport_name);

	kfree(tport);
}

static u32 scsiback_tpg_get_inst_index(struct se_portal_group *se_tpg)
{
	return 1;
}

static int scsiback_check_stop_free(struct se_cmd *se_cmd)
{
	return transport_generic_free_cmd(se_cmd, 0);
}

static void scsiback_release_cmd(struct se_cmd *se_cmd)
{
	target_free_tag(se_cmd->se_sess, se_cmd);
}

static u32 scsiback_sess_get_index(struct se_session *se_sess)
{
	return 0;
}

static int scsiback_write_pending(struct se_cmd *se_cmd)
{
	/* Go ahead and process the write immediately */
	target_execute_cmd(se_cmd);

	return 0;
}

static void scsiback_set_default_node_attrs(struct se_node_acl *nacl)
{
}

static int scsiback_get_cmd_state(struct se_cmd *se_cmd)
{
	return 0;
}

static int scsiback_queue_data_in(struct se_cmd *se_cmd)
{
	struct vscsibk_pend *pending_req = container_of(se_cmd,
				struct vscsibk_pend, se_cmd);

	pending_req->result = SAM_STAT_GOOD;
	scsiback_cmd_done(pending_req);
	return 0;
}

static int scsiback_queue_status(struct se_cmd *se_cmd)
{
	struct vscsibk_pend *pending_req = container_of(se_cmd,
				struct vscsibk_pend, se_cmd);

	if (se_cmd->sense_buffer &&
	    ((se_cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) ||
	     (se_cmd->se_cmd_flags & SCF_EMULATED_TASK_SENSE)))
		pending_req->result = SAM_STAT_CHECK_CONDITION;
	else
		pending_req->result = se_cmd->scsi_status;

	scsiback_cmd_done(pending_req);
	return 0;
}

static void scsiback_queue_tm_rsp(struct se_cmd *se_cmd)
{
	struct vscsibk_pend *pending_req = container_of(se_cmd,
				struct vscsibk_pend, se_cmd);

	complete(&pending_req->tmr_done);
}

static void scsiback_aborted_task(struct se_cmd *se_cmd)
{
}

static ssize_t scsiback_tpg_param_alias_show(struct config_item *item,
					     char *page)
{
	struct se_portal_group *se_tpg = param_to_tpg(item);
	struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
						se_tpg);
	ssize_t rb;

	mutex_lock(&tpg->tv_tpg_mutex);
	rb = snprintf(page, PAGE_SIZE, "%s\n", tpg->param_alias);
	mutex_unlock(&tpg->tv_tpg_mutex);

	return rb;
}

static ssize_t scsiback_tpg_param_alias_store(struct config_item *item,
					      const char *page, size_t count)
{
	struct se_portal_group *se_tpg = param_to_tpg(item);
	struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
						se_tpg);
	int len;

	if (strlen(page) >= VSCSI_NAMELEN) {
		pr_err("param alias: %s, exceeds max: %d\n", page,
			VSCSI_NAMELEN);
		return -EINVAL;
	}

	mutex_lock(&tpg->tv_tpg_mutex);
	len = snprintf(tpg->param_alias, VSCSI_NAMELEN, "%s", page);
	if (tpg->param_alias[len - 1] == '\n')
		tpg->param_alias[len - 1] = '\0';
	mutex_unlock(&tpg->tv_tpg_mutex);

	return count;
}

CONFIGFS_ATTR(scsiback_tpg_param_, alias);

static struct configfs_attribute *scsiback_param_attrs[] = {
	&scsiback_tpg_param_attr_alias,
	NULL,
};

static int scsiback_alloc_sess_cb(struct se_portal_group *se_tpg,
				  struct se_session *se_sess, void *p)
{
	struct scsiback_tpg *tpg = container_of(se_tpg,
				struct scsiback_tpg, se_tpg);

	tpg->tpg_nexus = p;
	return 0;
}

static int scsiback_make_nexus(struct scsiback_tpg *tpg,
				const char *name)
{
	struct scsiback_nexus *tv_nexus;
	int ret = 0;

	mutex_lock(&tpg->tv_tpg_mutex);
	if (tpg->tpg_nexus) {
		pr_debug("tpg->tpg_nexus already exists\n");
		ret = -EEXIST;
		goto out_unlock;
	}

	tv_nexus = kzalloc(sizeof(struct scsiback_nexus), GFP_KERNEL);
	if (!tv_nexus) {
		ret = -ENOMEM;
		goto out_unlock;
	}

	tv_nexus->tvn_se_sess = target_setup_session(&tpg->se_tpg,
						     VSCSI_DEFAULT_SESSION_TAGS,
						     sizeof(struct vscsibk_pend),
						     TARGET_PROT_NORMAL, name,
						     tv_nexus, scsiback_alloc_sess_cb);
	if (IS_ERR(tv_nexus->tvn_se_sess)) {
		kfree(tv_nexus);
		ret = -ENOMEM;
		goto out_unlock;
	}

out_unlock:
	mutex_unlock(&tpg->tv_tpg_mutex);
	return ret;
}

static int scsiback_drop_nexus(struct scsiback_tpg *tpg)
{
	struct se_session *se_sess;
	struct scsiback_nexus *tv_nexus;

	mutex_lock(&tpg->tv_tpg_mutex);
	tv_nexus = tpg->tpg_nexus;
	if (!tv_nexus) {
		mutex_unlock(&tpg->tv_tpg_mutex);
		return -ENODEV;
	}

	se_sess = tv_nexus->tvn_se_sess;
	if (!se_sess) {
		mutex_unlock(&tpg->tv_tpg_mutex);
		return -ENODEV;
	}

	if (tpg->tv_tpg_port_count != 0) {
		mutex_unlock(&tpg->tv_tpg_mutex);
		pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG port count: %d\n",
			tpg->tv_tpg_port_count);
		return -EBUSY;
	}

	if (tpg->tv_tpg_fe_count != 0) {
		mutex_unlock(&tpg->tv_tpg_mutex);
		pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG frontend count: %d\n",
			tpg->tv_tpg_fe_count);
		return -EBUSY;
	}

	pr_debug("Removing I_T Nexus to emulated %s Initiator Port: %s\n",
		scsiback_dump_proto_id(tpg->tport),
		tv_nexus->tvn_se_sess->se_node_acl->initiatorname);

	/*
	 * Release the SCSI I_T Nexus to the emulated xen-pvscsi Target Port
	 */
	target_remove_session(se_sess);
	tpg->tpg_nexus = NULL;
	mutex_unlock(&tpg->tv_tpg_mutex);

	kfree(tv_nexus);
	return 0;
}

static ssize_t scsiback_tpg_nexus_show(struct config_item *item, char *page)
{
	struct se_portal_group *se_tpg = to_tpg(item);
	struct scsiback_tpg *tpg = container_of(se_tpg,
				struct scsiback_tpg, se_tpg);
	struct scsiback_nexus *tv_nexus;
	ssize_t ret;

	mutex_lock(&tpg->tv_tpg_mutex);
	tv_nexus = tpg->tpg_nexus;
	if (!tv_nexus) {
		mutex_unlock(&tpg->tv_tpg_mutex);
		return -ENODEV;
	}
	ret = snprintf(page, PAGE_SIZE, "%s\n",
			tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
	mutex_unlock(&tpg->tv_tpg_mutex);

	return ret;
}

static ssize_t scsiback_tpg_nexus_store(struct config_item *item,
		const char *page, size_t count)
{
	struct se_portal_group *se_tpg = to_tpg(item);
	struct scsiback_tpg *tpg = container_of(se_tpg,
				struct scsiback_tpg, se_tpg);
	struct scsiback_tport *tport_wwn = tpg->tport;
	unsigned char i_port[VSCSI_NAMELEN], *ptr, *port_ptr;
	int ret;
	/*
	 * Shutdown the active I_T nexus if 'NULL' is passed.
	 */
	if (!strncmp(page, "NULL", 4)) {
		ret = scsiback_drop_nexus(tpg);
		return (!ret) ? count : ret;
	}
	/*
	 * Otherwise make sure the passed virtual Initiator port WWN matches
	 * the fabric protocol_id set in scsiback_make_tport(), and call
	 * scsiback_make_nexus().
	 */
	if (strlen(page) >= VSCSI_NAMELEN) {
		pr_err("Emulated NAA Sas Address: %s, exceeds max: %d\n",
			page, VSCSI_NAMELEN);
		return -EINVAL;
	}
	snprintf(&i_port[0], VSCSI_NAMELEN, "%s", page);

	ptr = strstr(i_port, "naa.");
	if (ptr) {
		if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_SAS) {
			pr_err("Passed SAS Initiator Port %s does not match target port protoid: %s\n",
				i_port, scsiback_dump_proto_id(tport_wwn));
			return -EINVAL;
		}
		port_ptr = &i_port[0];
		goto check_newline;
	}
	ptr = strstr(i_port, "fc.");
	if (ptr) {
		if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_FCP) {
			pr_err("Passed FCP Initiator Port %s does not match target port protoid: %s\n",
				i_port, scsiback_dump_proto_id(tport_wwn));
			return -EINVAL;
		}
		port_ptr = &i_port[3]; /* Skip over "fc." */
		goto check_newline;
	}
	ptr = strstr(i_port, "iqn.");
	if (ptr) {
		if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_ISCSI) {
			pr_err("Passed iSCSI Initiator Port %s does not match target port protoid: %s\n",
				i_port, scsiback_dump_proto_id(tport_wwn));
			return -EINVAL;
		}
		port_ptr = &i_port[0];
		goto check_newline;
	}
	pr_err("Unable to locate prefix for emulated Initiator Port: %s\n",
		i_port);
	return -EINVAL;
	/*
	 * Clear any trailing newline for the NAA WWN
	 */
check_newline:
	if (i_port[strlen(i_port) - 1] == '\n')
		i_port[strlen(i_port) - 1] = '\0';

	ret = scsiback_make_nexus(tpg, port_ptr);
	if (ret < 0)
		return ret;

	return count;
}

CONFIGFS_ATTR(scsiback_tpg_, nexus);

static struct configfs_attribute *scsiback_tpg_attrs[] = {
	&scsiback_tpg_attr_nexus,
	NULL,
};

static ssize_t
scsiback_wwn_version_show(struct config_item *item, char *page)
{
	return sprintf(page, "xen-pvscsi fabric module %s on %s/%s on "
		UTS_RELEASE"\n",
		VSCSI_VERSION, utsname()->sysname, utsname()->machine);
}

CONFIGFS_ATTR_RO(scsiback_wwn_, version);

static struct configfs_attribute *scsiback_wwn_attrs[] = {
	&scsiback_wwn_attr_version,
	NULL,
};

static int scsiback_port_link(struct se_portal_group *se_tpg,
			       struct se_lun *lun)
{
	struct scsiback_tpg *tpg = container_of(se_tpg,
				struct scsiback_tpg, se_tpg);

	mutex_lock(&tpg->tv_tpg_mutex);
	tpg->tv_tpg_port_count++;
	mutex_unlock(&tpg->tv_tpg_mutex);

	return 0;
}

static void scsiback_port_unlink(struct se_portal_group *se_tpg,
				  struct se_lun *lun)
{
	struct scsiback_tpg *tpg = container_of(se_tpg,
				struct scsiback_tpg, se_tpg);

	mutex_lock(&tpg->tv_tpg_mutex);
	tpg->tv_tpg_port_count--;
	mutex_unlock(&tpg->tv_tpg_mutex);
}

static struct se_portal_group *
scsiback_make_tpg(struct se_wwn *wwn, const char *name)
{
	struct scsiback_tport *tport = container_of(wwn,
			struct scsiback_tport, tport_wwn);

	struct scsiback_tpg *tpg;
	u16 tpgt;
	int ret;

	if (strstr(name, "tpgt_") != name)
		return ERR_PTR(-EINVAL);
	ret = kstrtou16(name + 5, 10, &tpgt);
	if (ret)
		return ERR_PTR(ret);

	tpg = kzalloc(sizeof(struct scsiback_tpg), GFP_KERNEL);
	if (!tpg)
		return ERR_PTR(-ENOMEM);

	mutex_init(&tpg->tv_tpg_mutex);
	INIT_LIST_HEAD(&tpg->tv_tpg_list);
	INIT_LIST_HEAD(&tpg->info_list);
	tpg->tport = tport;
	tpg->tport_tpgt = tpgt;

	ret = core_tpg_register(wwn, &tpg->se_tpg, tport->tport_proto_id);
	if (ret < 0) {
		kfree(tpg);
		return NULL;
	}
	mutex_lock(&scsiback_mutex);
	list_add_tail(&tpg->tv_tpg_list, &scsiback_list);
	mutex_unlock(&scsiback_mutex);

	return &tpg->se_tpg;
}

static void scsiback_drop_tpg(struct se_portal_group *se_tpg)
{
	struct scsiback_tpg *tpg = container_of(se_tpg,
				struct scsiback_tpg, se_tpg);

	mutex_lock(&scsiback_mutex);
	list_del(&tpg->tv_tpg_list);
	mutex_unlock(&scsiback_mutex);
	/*
	 * Release the virtual I_T Nexus for this xen-pvscsi TPG
	 */
	scsiback_drop_nexus(tpg);
	/*
	 * Deregister the se_tpg from TCM.
	 */
	core_tpg_deregister(se_tpg);
	kfree(tpg);
}

static int scsiback_check_true(struct se_portal_group *se_tpg)
{
	return 1;
}

static int scsiback_check_false(struct se_portal_group *se_tpg)
{
	return 0;
}

static const struct target_core_fabric_ops scsiback_ops = {
	.module				= THIS_MODULE,
	.fabric_name			= "xen-pvscsi",
	.tpg_get_wwn			= scsiback_get_fabric_wwn,
	.tpg_get_tag			= scsiback_get_tag,
	.tpg_check_demo_mode		= scsiback_check_true,
	.tpg_check_demo_mode_cache	= scsiback_check_true,
	.tpg_check_demo_mode_write_protect = scsiback_check_false,
	.tpg_check_prod_mode_write_protect = scsiback_check_false,
	.tpg_get_inst_index		= scsiback_tpg_get_inst_index,
	.check_stop_free		= scsiback_check_stop_free,
	.release_cmd			= scsiback_release_cmd,
	.sess_get_index			= scsiback_sess_get_index,
	.sess_get_initiator_sid		= NULL,
	.write_pending			= scsiback_write_pending,
	.set_default_node_attributes	= scsiback_set_default_node_attrs,
	.get_cmd_state			= scsiback_get_cmd_state,
	.queue_data_in			= scsiback_queue_data_in,
	.queue_status			= scsiback_queue_status,
	.queue_tm_rsp			= scsiback_queue_tm_rsp,
	.aborted_task			= scsiback_aborted_task,
	/*
	 * Setup callers for generic logic in target_core_fabric_configfs.c
	 */
	.fabric_make_wwn		= scsiback_make_tport,
	.fabric_drop_wwn		= scsiback_drop_tport,
	.fabric_make_tpg		= scsiback_make_tpg,
	.fabric_drop_tpg		= scsiback_drop_tpg,
	.fabric_post_link		= scsiback_port_link,
	.fabric_pre_unlink		= scsiback_port_unlink,

	.tfc_wwn_attrs			= scsiback_wwn_attrs,
	.tfc_tpg_base_attrs		= scsiback_tpg_attrs,
	.tfc_tpg_param_attrs		= scsiback_param_attrs,
};

static const struct xenbus_device_id scsiback_ids[] = {
	{ "vscsi" },
	{ "" }
};

static struct xenbus_driver scsiback_driver = {
	.ids			= scsiback_ids,
	.probe			= scsiback_probe,
	.remove			= scsiback_remove,
	.otherend_changed	= scsiback_frontend_changed
};

static int __init scsiback_init(void)
{
	int ret;

	if (!xen_domain())
		return -ENODEV;

	pr_debug("xen-pvscsi: fabric module %s on %s/%s on "UTS_RELEASE"\n",
		 VSCSI_VERSION, utsname()->sysname, utsname()->machine);

	ret = xenbus_register_backend(&scsiback_driver);
	if (ret)
		goto out;

	ret = target_register_template(&scsiback_ops);
	if (ret)
		goto out_unregister_xenbus;

	return 0;

out_unregister_xenbus:
	xenbus_unregister_driver(&scsiback_driver);
out:
	pr_err("%s: error %d\n", __func__, ret);
	return ret;
}

static void __exit scsiback_exit(void)
{
	target_unregister_template(&scsiback_ops);
	xenbus_unregister_driver(&scsiback_driver);
}

module_init(scsiback_init);
module_exit(scsiback_exit);

MODULE_DESCRIPTION("Xen SCSI backend driver");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_ALIAS("xen-backend:vscsi");
MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");