aboutsummaryrefslogtreecommitdiff
path: root/drivers/scsi/storvsc_drv.c
blob: 17d7404272400dd1a76989a3965e0c4b85343036 (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
/*
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Authors:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 *   K. Y. Srinivasan <kys@microsoft.com>
 */

#include <linux/kernel.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/hyperv.h>
#include <linux/mempool.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_devinfo.h>
#include <scsi/scsi_dbg.h>

/*
 * All wire protocol details (storage protocol between the guest and the host)
 * are consolidated here.
 *
 * Begin protocol definitions.
 */

/*
 * Version history:
 * V1 Beta: 0.1
 * V1 RC < 2008/1/31: 1.0
 * V1 RC > 2008/1/31:  2.0
 * Win7: 4.2
 * Win8: 5.1
 */


#define VMSTOR_WIN7_MAJOR 4
#define VMSTOR_WIN7_MINOR 2

#define VMSTOR_WIN8_MAJOR 5
#define VMSTOR_WIN8_MINOR 1


/*  Packet structure describing virtual storage requests. */
enum vstor_packet_operation {
	VSTOR_OPERATION_COMPLETE_IO		= 1,
	VSTOR_OPERATION_REMOVE_DEVICE		= 2,
	VSTOR_OPERATION_EXECUTE_SRB		= 3,
	VSTOR_OPERATION_RESET_LUN		= 4,
	VSTOR_OPERATION_RESET_ADAPTER		= 5,
	VSTOR_OPERATION_RESET_BUS		= 6,
	VSTOR_OPERATION_BEGIN_INITIALIZATION	= 7,
	VSTOR_OPERATION_END_INITIALIZATION	= 8,
	VSTOR_OPERATION_QUERY_PROTOCOL_VERSION	= 9,
	VSTOR_OPERATION_QUERY_PROPERTIES	= 10,
	VSTOR_OPERATION_ENUMERATE_BUS		= 11,
	VSTOR_OPERATION_FCHBA_DATA              = 12,
	VSTOR_OPERATION_CREATE_SUB_CHANNELS     = 13,
	VSTOR_OPERATION_MAXIMUM                 = 13
};

/*
 * WWN packet for Fibre Channel HBA
 */

struct hv_fc_wwn_packet {
	bool	primary_active;
	u8	reserved1;
	u8	reserved2;
	u8	primary_port_wwn[8];
	u8	primary_node_wwn[8];
	u8	secondary_port_wwn[8];
	u8	secondary_node_wwn[8];
};



/*
 * SRB Flag Bits
 */

#define SRB_FLAGS_QUEUE_ACTION_ENABLE		0x00000002
#define SRB_FLAGS_DISABLE_DISCONNECT		0x00000004
#define SRB_FLAGS_DISABLE_SYNCH_TRANSFER	0x00000008
#define SRB_FLAGS_BYPASS_FROZEN_QUEUE		0x00000010
#define SRB_FLAGS_DISABLE_AUTOSENSE		0x00000020
#define SRB_FLAGS_DATA_IN			0x00000040
#define SRB_FLAGS_DATA_OUT			0x00000080
#define SRB_FLAGS_NO_DATA_TRANSFER		0x00000000
#define SRB_FLAGS_UNSPECIFIED_DIRECTION	(SRB_FLAGS_DATA_IN | SRB_FLAGS_DATA_OUT)
#define SRB_FLAGS_NO_QUEUE_FREEZE		0x00000100
#define SRB_FLAGS_ADAPTER_CACHE_ENABLE		0x00000200
#define SRB_FLAGS_FREE_SENSE_BUFFER		0x00000400

/*
 * This flag indicates the request is part of the workflow for processing a D3.
 */
#define SRB_FLAGS_D3_PROCESSING			0x00000800
#define SRB_FLAGS_IS_ACTIVE			0x00010000
#define SRB_FLAGS_ALLOCATED_FROM_ZONE		0x00020000
#define SRB_FLAGS_SGLIST_FROM_POOL		0x00040000
#define SRB_FLAGS_BYPASS_LOCKED_QUEUE		0x00080000
#define SRB_FLAGS_NO_KEEP_AWAKE			0x00100000
#define SRB_FLAGS_PORT_DRIVER_ALLOCSENSE	0x00200000
#define SRB_FLAGS_PORT_DRIVER_SENSEHASPORT	0x00400000
#define SRB_FLAGS_DONT_START_NEXT_PACKET	0x00800000
#define SRB_FLAGS_PORT_DRIVER_RESERVED		0x0F000000
#define SRB_FLAGS_CLASS_DRIVER_RESERVED		0xF0000000


/*
 * Platform neutral description of a scsi request -
 * this remains the same across the write regardless of 32/64 bit
 * note: it's patterned off the SCSI_PASS_THROUGH structure
 */
#define STORVSC_MAX_CMD_LEN			0x10

#define POST_WIN7_STORVSC_SENSE_BUFFER_SIZE	0x14
#define PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE	0x12

#define STORVSC_SENSE_BUFFER_SIZE		0x14
#define STORVSC_MAX_BUF_LEN_WITH_PADDING	0x14

/*
 * Sense buffer size changed in win8; have a run-time
 * variable to track the size we should use.
 */
static int sense_buffer_size;

/*
 * The size of the vmscsi_request has changed in win8. The
 * additional size is because of new elements added to the
 * structure. These elements are valid only when we are talking
 * to a win8 host.
 * Track the correction to size we need to apply.
 */

static int vmscsi_size_delta;
static int vmstor_current_major;
static int vmstor_current_minor;

struct vmscsi_win8_extension {
	/*
	 * The following were added in Windows 8
	 */
	u16 reserve;
	u8  queue_tag;
	u8  queue_action;
	u32 srb_flags;
	u32 time_out_value;
	u32 queue_sort_ey;
} __packed;

struct vmscsi_request {
	u16 length;
	u8 srb_status;
	u8 scsi_status;

	u8  port_number;
	u8  path_id;
	u8  target_id;
	u8  lun;

	u8  cdb_length;
	u8  sense_info_length;
	u8  data_in;
	u8  reserved;

	u32 data_transfer_length;

	union {
		u8 cdb[STORVSC_MAX_CMD_LEN];
		u8 sense_data[STORVSC_SENSE_BUFFER_SIZE];
		u8 reserved_array[STORVSC_MAX_BUF_LEN_WITH_PADDING];
	};
	/*
	 * The following was added in win8.
	 */
	struct vmscsi_win8_extension win8_extension;

} __attribute((packed));


/*
 * This structure is sent during the intialization phase to get the different
 * properties of the channel.
 */

#define STORAGE_CHANNEL_SUPPORTS_MULTI_CHANNEL		0x1

struct vmstorage_channel_properties {
	u32 reserved;
	u16 max_channel_cnt;
	u16 reserved1;

	u32 flags;
	u32   max_transfer_bytes;

	u64  reserved2;
} __packed;

/*  This structure is sent during the storage protocol negotiations. */
struct vmstorage_protocol_version {
	/* Major (MSW) and minor (LSW) version numbers. */
	u16 major_minor;

	/*
	 * Revision number is auto-incremented whenever this file is changed
	 * (See FILL_VMSTOR_REVISION macro above).  Mismatch does not
	 * definitely indicate incompatibility--but it does indicate mismatched
	 * builds.
	 * This is only used on the windows side. Just set it to 0.
	 */
	u16 revision;
} __packed;

/* Channel Property Flags */
#define STORAGE_CHANNEL_REMOVABLE_FLAG		0x1
#define STORAGE_CHANNEL_EMULATED_IDE_FLAG	0x2

struct vstor_packet {
	/* Requested operation type */
	enum vstor_packet_operation operation;

	/*  Flags - see below for values */
	u32 flags;

	/* Status of the request returned from the server side. */
	u32 status;

	/* Data payload area */
	union {
		/*
		 * Structure used to forward SCSI commands from the
		 * client to the server.
		 */
		struct vmscsi_request vm_srb;

		/* Structure used to query channel properties. */
		struct vmstorage_channel_properties storage_channel_properties;

		/* Used during version negotiations. */
		struct vmstorage_protocol_version version;

		/* Fibre channel address packet */
		struct hv_fc_wwn_packet wwn_packet;

		/* Number of sub-channels to create */
		u16 sub_channel_count;

		/* This will be the maximum of the union members */
		u8  buffer[0x34];
	};
} __packed;

/*
 * Packet Flags:
 *
 * This flag indicates that the server should send back a completion for this
 * packet.
 */

#define REQUEST_COMPLETION_FLAG	0x1

/* Matches Windows-end */
enum storvsc_request_type {
	WRITE_TYPE = 0,
	READ_TYPE,
	UNKNOWN_TYPE,
};

/*
 * SRB status codes and masks; a subset of the codes used here.
 */

#define SRB_STATUS_AUTOSENSE_VALID	0x80
#define SRB_STATUS_INVALID_LUN	0x20
#define SRB_STATUS_SUCCESS	0x01
#define SRB_STATUS_ABORTED	0x02
#define SRB_STATUS_ERROR	0x04

/*
 * This is the end of Protocol specific defines.
 */


/*
 * We setup a mempool to allocate request structures for this driver
 * on a per-lun basis. The following define specifies the number of
 * elements in the pool.
 */

#define STORVSC_MIN_BUF_NR				64
static int storvsc_ringbuffer_size = (20 * PAGE_SIZE);

module_param(storvsc_ringbuffer_size, int, S_IRUGO);
MODULE_PARM_DESC(storvsc_ringbuffer_size, "Ring buffer size (bytes)");

/*
 * Timeout in seconds for all devices managed by this driver.
 */
static int storvsc_timeout = 180;

#define STORVSC_MAX_IO_REQUESTS				200

static void storvsc_on_channel_callback(void *context);

/*
 * In Hyper-V, each port/path/target maps to 1 scsi host adapter.  In
 * reality, the path/target is not used (ie always set to 0) so our
 * scsi host adapter essentially has 1 bus with 1 target that contains
 * up to 256 luns.
 */
#define STORVSC_MAX_LUNS_PER_TARGET			64
#define STORVSC_MAX_TARGETS				1
#define STORVSC_MAX_CHANNELS				1



struct storvsc_cmd_request {
	struct list_head entry;
	struct scsi_cmnd *cmd;

	unsigned int bounce_sgl_count;
	struct scatterlist *bounce_sgl;

	struct hv_device *device;

	/* Synchronize the request/response if needed */
	struct completion wait_event;

	unsigned char *sense_buffer;
	struct hv_multipage_buffer data_buffer;
	struct vstor_packet vstor_packet;
};


/* A storvsc device is a device object that contains a vmbus channel */
struct storvsc_device {
	struct hv_device *device;

	bool	 destroy;
	bool	 drain_notify;
	bool	 open_sub_channel;
	atomic_t num_outstanding_req;
	struct Scsi_Host *host;

	wait_queue_head_t waiting_to_drain;

	/*
	 * Each unique Port/Path/Target represents 1 channel ie scsi
	 * controller. In reality, the pathid, targetid is always 0
	 * and the port is set by us
	 */
	unsigned int port_number;
	unsigned char path_id;
	unsigned char target_id;

	/* Used for vsc/vsp channel reset process */
	struct storvsc_cmd_request init_request;
	struct storvsc_cmd_request reset_request;
};

struct stor_mem_pools {
	struct kmem_cache *request_pool;
	mempool_t *request_mempool;
};

struct hv_host_device {
	struct hv_device *dev;
	unsigned int port;
	unsigned char path;
	unsigned char target;
};

struct storvsc_scan_work {
	struct work_struct work;
	struct Scsi_Host *host;
	uint lun;
};

static void storvsc_device_scan(struct work_struct *work)
{
	struct storvsc_scan_work *wrk;
	uint lun;
	struct scsi_device *sdev;

	wrk = container_of(work, struct storvsc_scan_work, work);
	lun = wrk->lun;

	sdev = scsi_device_lookup(wrk->host, 0, 0, lun);
	if (!sdev)
		goto done;
	scsi_rescan_device(&sdev->sdev_gendev);
	scsi_device_put(sdev);

done:
	kfree(wrk);
}

static void storvsc_bus_scan(struct work_struct *work)
{
	struct storvsc_scan_work *wrk;
	int id, order_id;

	wrk = container_of(work, struct storvsc_scan_work, work);
	for (id = 0; id < wrk->host->max_id; ++id) {
		if (wrk->host->reverse_ordering)
			order_id = wrk->host->max_id - id - 1;
		else
			order_id = id;

		scsi_scan_target(&wrk->host->shost_gendev, 0,
				order_id, SCAN_WILD_CARD, 1);
	}
	kfree(wrk);
}

static void storvsc_remove_lun(struct work_struct *work)
{
	struct storvsc_scan_work *wrk;
	struct scsi_device *sdev;

	wrk = container_of(work, struct storvsc_scan_work, work);
	if (!scsi_host_get(wrk->host))
		goto done;

	sdev = scsi_device_lookup(wrk->host, 0, 0, wrk->lun);

	if (sdev) {
		scsi_remove_device(sdev);
		scsi_device_put(sdev);
	}
	scsi_host_put(wrk->host);

done:
	kfree(wrk);
}

/*
 * Major/minor macros.  Minor version is in LSB, meaning that earlier flat
 * version numbers will be interpreted as "0.x" (i.e., 1 becomes 0.1).
 */

static inline u16 storvsc_get_version(u8 major, u8 minor)
{
	u16 version;

	version = ((major << 8) | minor);
	return version;
}

/*
 * We can get incoming messages from the host that are not in response to
 * messages that we have sent out. An example of this would be messages
 * received by the guest to notify dynamic addition/removal of LUNs. To
 * deal with potential race conditions where the driver may be in the
 * midst of being unloaded when we might receive an unsolicited message
 * from the host, we have implemented a mechanism to gurantee sequential
 * consistency:
 *
 * 1) Once the device is marked as being destroyed, we will fail all
 *    outgoing messages.
 * 2) We permit incoming messages when the device is being destroyed,
 *    only to properly account for messages already sent out.
 */

static inline struct storvsc_device *get_out_stor_device(
					struct hv_device *device)
{
	struct storvsc_device *stor_device;

	stor_device = hv_get_drvdata(device);

	if (stor_device && stor_device->destroy)
		stor_device = NULL;

	return stor_device;
}


static inline void storvsc_wait_to_drain(struct storvsc_device *dev)
{
	dev->drain_notify = true;
	wait_event(dev->waiting_to_drain,
		   atomic_read(&dev->num_outstanding_req) == 0);
	dev->drain_notify = false;
}

static inline struct storvsc_device *get_in_stor_device(
					struct hv_device *device)
{
	struct storvsc_device *stor_device;

	stor_device = hv_get_drvdata(device);

	if (!stor_device)
		goto get_in_err;

	/*
	 * If the device is being destroyed; allow incoming
	 * traffic only to cleanup outstanding requests.
	 */

	if (stor_device->destroy  &&
		(atomic_read(&stor_device->num_outstanding_req) == 0))
		stor_device = NULL;

get_in_err:
	return stor_device;

}

static void destroy_bounce_buffer(struct scatterlist *sgl,
				  unsigned int sg_count)
{
	int i;
	struct page *page_buf;

	for (i = 0; i < sg_count; i++) {
		page_buf = sg_page((&sgl[i]));
		if (page_buf != NULL)
			__free_page(page_buf);
	}

	kfree(sgl);
}

static int do_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count)
{
	int i;

	/* No need to check */
	if (sg_count < 2)
		return -1;

	/* We have at least 2 sg entries */
	for (i = 0; i < sg_count; i++) {
		if (i == 0) {
			/* make sure 1st one does not have hole */
			if (sgl[i].offset + sgl[i].length != PAGE_SIZE)
				return i;
		} else if (i == sg_count - 1) {
			/* make sure last one does not have hole */
			if (sgl[i].offset != 0)
				return i;
		} else {
			/* make sure no hole in the middle */
			if (sgl[i].length != PAGE_SIZE || sgl[i].offset != 0)
				return i;
		}
	}
	return -1;
}

static struct scatterlist *create_bounce_buffer(struct scatterlist *sgl,
						unsigned int sg_count,
						unsigned int len,
						int write)
{
	int i;
	int num_pages;
	struct scatterlist *bounce_sgl;
	struct page *page_buf;
	unsigned int buf_len = ((write == WRITE_TYPE) ? 0 : PAGE_SIZE);

	num_pages = ALIGN(len, PAGE_SIZE) >> PAGE_SHIFT;

	bounce_sgl = kcalloc(num_pages, sizeof(struct scatterlist), GFP_ATOMIC);
	if (!bounce_sgl)
		return NULL;

	sg_init_table(bounce_sgl, num_pages);
	for (i = 0; i < num_pages; i++) {
		page_buf = alloc_page(GFP_ATOMIC);
		if (!page_buf)
			goto cleanup;
		sg_set_page(&bounce_sgl[i], page_buf, buf_len, 0);
	}

	return bounce_sgl;

cleanup:
	destroy_bounce_buffer(bounce_sgl, num_pages);
	return NULL;
}

/* Disgusting wrapper functions */
static inline unsigned long sg_kmap_atomic(struct scatterlist *sgl, int idx)
{
	void *addr = kmap_atomic(sg_page(sgl + idx));
	return (unsigned long)addr;
}

static inline void sg_kunmap_atomic(unsigned long addr)
{
	kunmap_atomic((void *)addr);
}


/* Assume the original sgl has enough room */
static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl,
					    struct scatterlist *bounce_sgl,
					    unsigned int orig_sgl_count,
					    unsigned int bounce_sgl_count)
{
	int i;
	int j = 0;
	unsigned long src, dest;
	unsigned int srclen, destlen, copylen;
	unsigned int total_copied = 0;
	unsigned long bounce_addr = 0;
	unsigned long dest_addr = 0;
	unsigned long flags;

	local_irq_save(flags);

	for (i = 0; i < orig_sgl_count; i++) {
		dest_addr = sg_kmap_atomic(orig_sgl,i) + orig_sgl[i].offset;
		dest = dest_addr;
		destlen = orig_sgl[i].length;

		if (bounce_addr == 0)
			bounce_addr = sg_kmap_atomic(bounce_sgl,j);

		while (destlen) {
			src = bounce_addr + bounce_sgl[j].offset;
			srclen = bounce_sgl[j].length - bounce_sgl[j].offset;

			copylen = min(srclen, destlen);
			memcpy((void *)dest, (void *)src, copylen);

			total_copied += copylen;
			bounce_sgl[j].offset += copylen;
			destlen -= copylen;
			dest += copylen;

			if (bounce_sgl[j].offset == bounce_sgl[j].length) {
				/* full */
				sg_kunmap_atomic(bounce_addr);
				j++;

				/*
				 * It is possible that the number of elements
				 * in the bounce buffer may not be equal to
				 * the number of elements in the original
				 * scatter list. Handle this correctly.
				 */

				if (j == bounce_sgl_count) {
					/*
					 * We are done; cleanup and return.
					 */
					sg_kunmap_atomic(dest_addr - orig_sgl[i].offset);
					local_irq_restore(flags);
					return total_copied;
				}

				/* if we need to use another bounce buffer */
				if (destlen || i != orig_sgl_count - 1)
					bounce_addr = sg_kmap_atomic(bounce_sgl,j);
			} else if (destlen == 0 && i == orig_sgl_count - 1) {
				/* unmap the last bounce that is < PAGE_SIZE */
				sg_kunmap_atomic(bounce_addr);
			}
		}

		sg_kunmap_atomic(dest_addr - orig_sgl[i].offset);
	}

	local_irq_restore(flags);

	return total_copied;
}

/* Assume the bounce_sgl has enough room ie using the create_bounce_buffer() */
static unsigned int copy_to_bounce_buffer(struct scatterlist *orig_sgl,
					  struct scatterlist *bounce_sgl,
					  unsigned int orig_sgl_count)
{
	int i;
	int j = 0;
	unsigned long src, dest;
	unsigned int srclen, destlen, copylen;
	unsigned int total_copied = 0;
	unsigned long bounce_addr = 0;
	unsigned long src_addr = 0;
	unsigned long flags;

	local_irq_save(flags);

	for (i = 0; i < orig_sgl_count; i++) {
		src_addr = sg_kmap_atomic(orig_sgl,i) + orig_sgl[i].offset;
		src = src_addr;
		srclen = orig_sgl[i].length;

		if (bounce_addr == 0)
			bounce_addr = sg_kmap_atomic(bounce_sgl,j);

		while (srclen) {
			/* assume bounce offset always == 0 */
			dest = bounce_addr + bounce_sgl[j].length;
			destlen = PAGE_SIZE - bounce_sgl[j].length;

			copylen = min(srclen, destlen);
			memcpy((void *)dest, (void *)src, copylen);

			total_copied += copylen;
			bounce_sgl[j].length += copylen;
			srclen -= copylen;
			src += copylen;

			if (bounce_sgl[j].length == PAGE_SIZE) {
				/* full..move to next entry */
				sg_kunmap_atomic(bounce_addr);
				j++;

				/* if we need to use another bounce buffer */
				if (srclen || i != orig_sgl_count - 1)
					bounce_addr = sg_kmap_atomic(bounce_sgl,j);

			} else if (srclen == 0 && i == orig_sgl_count - 1) {
				/* unmap the last bounce that is < PAGE_SIZE */
				sg_kunmap_atomic(bounce_addr);
			}
		}

		sg_kunmap_atomic(src_addr - orig_sgl[i].offset);
	}

	local_irq_restore(flags);

	return total_copied;
}

static void handle_sc_creation(struct vmbus_channel *new_sc)
{
	struct hv_device *device = new_sc->primary_channel->device_obj;
	struct storvsc_device *stor_device;
	struct vmstorage_channel_properties props;

	stor_device = get_out_stor_device(device);
	if (!stor_device)
		return;

	if (stor_device->open_sub_channel == false)
		return;

	memset(&props, 0, sizeof(struct vmstorage_channel_properties));

	vmbus_open(new_sc,
		   storvsc_ringbuffer_size,
		   storvsc_ringbuffer_size,
		   (void *)&props,
		   sizeof(struct vmstorage_channel_properties),
		   storvsc_on_channel_callback, new_sc);
}

static void  handle_multichannel_storage(struct hv_device *device, int max_chns)
{
	struct storvsc_device *stor_device;
	int num_cpus = num_online_cpus();
	int num_sc;
	struct storvsc_cmd_request *request;
	struct vstor_packet *vstor_packet;
	int ret, t;

	num_sc = ((max_chns > num_cpus) ? num_cpus : max_chns);
	stor_device = get_out_stor_device(device);
	if (!stor_device)
		return;

	request = &stor_device->init_request;
	vstor_packet = &request->vstor_packet;

	stor_device->open_sub_channel = true;
	/*
	 * Establish a handler for dealing with subchannels.
	 */
	vmbus_set_sc_create_callback(device->channel, handle_sc_creation);

	/*
	 * Check to see if sub-channels have already been created. This
	 * can happen when this driver is re-loaded after unloading.
	 */

	if (vmbus_are_subchannels_present(device->channel))
		return;

	stor_device->open_sub_channel = false;
	/*
	 * Request the host to create sub-channels.
	 */
	memset(request, 0, sizeof(struct storvsc_cmd_request));
	init_completion(&request->wait_event);
	vstor_packet->operation = VSTOR_OPERATION_CREATE_SUB_CHANNELS;
	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
	vstor_packet->sub_channel_count = num_sc;

	ret = vmbus_sendpacket(device->channel, vstor_packet,
			       (sizeof(struct vstor_packet) -
			       vmscsi_size_delta),
			       (unsigned long)request,
			       VM_PKT_DATA_INBAND,
			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);

	if (ret != 0)
		return;

	t = wait_for_completion_timeout(&request->wait_event, 10*HZ);
	if (t == 0)
		return;

	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
	    vstor_packet->status != 0)
		return;

	/*
	 * Now that we created the sub-channels, invoke the check; this
	 * may trigger the callback.
	 */
	stor_device->open_sub_channel = true;
	vmbus_are_subchannels_present(device->channel);
}

static int storvsc_channel_init(struct hv_device *device)
{
	struct storvsc_device *stor_device;
	struct storvsc_cmd_request *request;
	struct vstor_packet *vstor_packet;
	int ret, t;
	int max_chns;
	bool process_sub_channels = false;

	stor_device = get_out_stor_device(device);
	if (!stor_device)
		return -ENODEV;

	request = &stor_device->init_request;
	vstor_packet = &request->vstor_packet;

	/*
	 * Now, initiate the vsc/vsp initialization protocol on the open
	 * channel
	 */
	memset(request, 0, sizeof(struct storvsc_cmd_request));
	init_completion(&request->wait_event);
	vstor_packet->operation = VSTOR_OPERATION_BEGIN_INITIALIZATION;
	vstor_packet->flags = REQUEST_COMPLETION_FLAG;

	ret = vmbus_sendpacket(device->channel, vstor_packet,
			       (sizeof(struct vstor_packet) -
			       vmscsi_size_delta),
			       (unsigned long)request,
			       VM_PKT_DATA_INBAND,
			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
	if (ret != 0)
		goto cleanup;

	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
	if (t == 0) {
		ret = -ETIMEDOUT;
		goto cleanup;
	}

	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
	    vstor_packet->status != 0)
		goto cleanup;


	/* reuse the packet for version range supported */
	memset(vstor_packet, 0, sizeof(struct vstor_packet));
	vstor_packet->operation = VSTOR_OPERATION_QUERY_PROTOCOL_VERSION;
	vstor_packet->flags = REQUEST_COMPLETION_FLAG;

	vstor_packet->version.major_minor =
		storvsc_get_version(vmstor_current_major, vmstor_current_minor);

	/*
	 * The revision number is only used in Windows; set it to 0.
	 */
	vstor_packet->version.revision = 0;

	ret = vmbus_sendpacket(device->channel, vstor_packet,
			       (sizeof(struct vstor_packet) -
				vmscsi_size_delta),
			       (unsigned long)request,
			       VM_PKT_DATA_INBAND,
			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
	if (ret != 0)
		goto cleanup;

	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
	if (t == 0) {
		ret = -ETIMEDOUT;
		goto cleanup;
	}

	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
	    vstor_packet->status != 0)
		goto cleanup;


	memset(vstor_packet, 0, sizeof(struct vstor_packet));
	vstor_packet->operation = VSTOR_OPERATION_QUERY_PROPERTIES;
	vstor_packet->flags = REQUEST_COMPLETION_FLAG;

	ret = vmbus_sendpacket(device->channel, vstor_packet,
			       (sizeof(struct vstor_packet) -
				vmscsi_size_delta),
			       (unsigned long)request,
			       VM_PKT_DATA_INBAND,
			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);

	if (ret != 0)
		goto cleanup;

	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
	if (t == 0) {
		ret = -ETIMEDOUT;
		goto cleanup;
	}

	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
	    vstor_packet->status != 0)
		goto cleanup;

	/*
	 * Check to see if multi-channel support is there.
	 * Hosts that implement protocol version of 5.1 and above
	 * support multi-channel.
	 */
	max_chns = vstor_packet->storage_channel_properties.max_channel_cnt;
	if ((vmbus_proto_version != VERSION_WIN7) &&
	   (vmbus_proto_version != VERSION_WS2008))  {
		if (vstor_packet->storage_channel_properties.flags &
		    STORAGE_CHANNEL_SUPPORTS_MULTI_CHANNEL)
			process_sub_channels = true;
	}

	memset(vstor_packet, 0, sizeof(struct vstor_packet));
	vstor_packet->operation = VSTOR_OPERATION_END_INITIALIZATION;
	vstor_packet->flags = REQUEST_COMPLETION_FLAG;

	ret = vmbus_sendpacket(device->channel, vstor_packet,
			       (sizeof(struct vstor_packet) -
				vmscsi_size_delta),
			       (unsigned long)request,
			       VM_PKT_DATA_INBAND,
			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);

	if (ret != 0)
		goto cleanup;

	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
	if (t == 0) {
		ret = -ETIMEDOUT;
		goto cleanup;
	}

	if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
	    vstor_packet->status != 0)
		goto cleanup;

	if (process_sub_channels)
		handle_multichannel_storage(device, max_chns);


cleanup:
	return ret;
}

static void storvsc_handle_error(struct vmscsi_request *vm_srb,
				struct scsi_cmnd *scmnd,
				struct Scsi_Host *host,
				u8 asc, u8 ascq)
{
	struct storvsc_scan_work *wrk;
	void (*process_err_fn)(struct work_struct *work);
	bool do_work = false;

	switch (vm_srb->srb_status) {
	case SRB_STATUS_ERROR:
		/*
		 * If there is an error; offline the device since all
		 * error recovery strategies would have already been
		 * deployed on the host side. However, if the command
		 * were a pass-through command deal with it appropriately.
		 */
		switch (scmnd->cmnd[0]) {
		case ATA_16:
		case ATA_12:
			set_host_byte(scmnd, DID_PASSTHROUGH);
			break;
		default:
			set_host_byte(scmnd, DID_TARGET_FAILURE);
		}
		break;
	case SRB_STATUS_INVALID_LUN:
		do_work = true;
		process_err_fn = storvsc_remove_lun;
		break;
	case (SRB_STATUS_ABORTED | SRB_STATUS_AUTOSENSE_VALID):
		if ((asc == 0x2a) && (ascq == 0x9)) {
			do_work = true;
			process_err_fn = storvsc_device_scan;
			/*
			 * Retry the I/O that trigerred this.
			 */
			set_host_byte(scmnd, DID_REQUEUE);
		}
		break;
	}

	if (!do_work)
		return;

	/*
	 * We need to schedule work to process this error; schedule it.
	 */
	wrk = kmalloc(sizeof(struct storvsc_scan_work), GFP_ATOMIC);
	if (!wrk) {
		set_host_byte(scmnd, DID_TARGET_FAILURE);
		return;
	}

	wrk->host = host;
	wrk->lun = vm_srb->lun;
	INIT_WORK(&wrk->work, process_err_fn);
	schedule_work(&wrk->work);
}


static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
{
	struct scsi_cmnd *scmnd = cmd_request->cmd;
	struct hv_host_device *host_dev = shost_priv(scmnd->device->host);
	void (*scsi_done_fn)(struct scsi_cmnd *);
	struct scsi_sense_hdr sense_hdr;
	struct vmscsi_request *vm_srb;
	struct stor_mem_pools *memp = scmnd->device->hostdata;
	struct Scsi_Host *host;
	struct storvsc_device *stor_dev;
	struct hv_device *dev = host_dev->dev;

	stor_dev = get_in_stor_device(dev);
	host = stor_dev->host;

	vm_srb = &cmd_request->vstor_packet.vm_srb;
	if (cmd_request->bounce_sgl_count) {
		if (vm_srb->data_in == READ_TYPE)
			copy_from_bounce_buffer(scsi_sglist(scmnd),
					cmd_request->bounce_sgl,
					scsi_sg_count(scmnd),
					cmd_request->bounce_sgl_count);
		destroy_bounce_buffer(cmd_request->bounce_sgl,
					cmd_request->bounce_sgl_count);
	}

	scmnd->result = vm_srb->scsi_status;

	if (scmnd->result) {
		if (scsi_normalize_sense(scmnd->sense_buffer,
				SCSI_SENSE_BUFFERSIZE, &sense_hdr))
			scsi_print_sense_hdr("storvsc", &sense_hdr);
	}

	if (vm_srb->srb_status != SRB_STATUS_SUCCESS)
		storvsc_handle_error(vm_srb, scmnd, host, sense_hdr.asc,
					 sense_hdr.ascq);

	scsi_set_resid(scmnd,
		cmd_request->data_buffer.len -
		vm_srb->data_transfer_length);

	scsi_done_fn = scmnd->scsi_done;

	scmnd->host_scribble = NULL;
	scmnd->scsi_done = NULL;

	scsi_done_fn(scmnd);

	mempool_free(cmd_request, memp->request_mempool);
}

static void storvsc_on_io_completion(struct hv_device *device,
				  struct vstor_packet *vstor_packet,
				  struct storvsc_cmd_request *request)
{
	struct storvsc_device *stor_device;
	struct vstor_packet *stor_pkt;

	stor_device = hv_get_drvdata(device);
	stor_pkt = &request->vstor_packet;

	/*
	 * The current SCSI handling on the host side does
	 * not correctly handle:
	 * INQUIRY command with page code parameter set to 0x80
	 * MODE_SENSE command with cmd[2] == 0x1c
	 *
	 * Setup srb and scsi status so this won't be fatal.
	 * We do this so we can distinguish truly fatal failues
	 * (srb status == 0x4) and off-line the device in that case.
	 */

	if ((stor_pkt->vm_srb.cdb[0] == INQUIRY) ||
	   (stor_pkt->vm_srb.cdb[0] == MODE_SENSE)) {
		vstor_packet->vm_srb.scsi_status = 0;
		vstor_packet->vm_srb.srb_status = SRB_STATUS_SUCCESS;
	}


	/* Copy over the status...etc */
	stor_pkt->vm_srb.scsi_status = vstor_packet->vm_srb.scsi_status;
	stor_pkt->vm_srb.srb_status = vstor_packet->vm_srb.srb_status;
	stor_pkt->vm_srb.sense_info_length =
	vstor_packet->vm_srb.sense_info_length;

	if (vstor_packet->vm_srb.scsi_status != 0 ||
		vstor_packet->vm_srb.srb_status != SRB_STATUS_SUCCESS){
		dev_warn(&device->device,
			 "cmd 0x%x scsi status 0x%x srb status 0x%x\n",
			 stor_pkt->vm_srb.cdb[0],
			 vstor_packet->vm_srb.scsi_status,
			 vstor_packet->vm_srb.srb_status);
	}

	if ((vstor_packet->vm_srb.scsi_status & 0xFF) == 0x02) {
		/* CHECK_CONDITION */
		if (vstor_packet->vm_srb.srb_status &
			SRB_STATUS_AUTOSENSE_VALID) {
			/* autosense data available */
			dev_warn(&device->device,
				 "stor pkt %p autosense data valid - len %d\n",
				 request,
				 vstor_packet->vm_srb.sense_info_length);

			memcpy(request->sense_buffer,
			       vstor_packet->vm_srb.sense_data,
			       vstor_packet->vm_srb.sense_info_length);

		}
	}

	stor_pkt->vm_srb.data_transfer_length =
	vstor_packet->vm_srb.data_transfer_length;

	storvsc_command_completion(request);

	if (atomic_dec_and_test(&stor_device->num_outstanding_req) &&
		stor_device->drain_notify)
		wake_up(&stor_device->waiting_to_drain);


}

static void storvsc_on_receive(struct hv_device *device,
			     struct vstor_packet *vstor_packet,
			     struct storvsc_cmd_request *request)
{
	struct storvsc_scan_work *work;
	struct storvsc_device *stor_device;

	switch (vstor_packet->operation) {
	case VSTOR_OPERATION_COMPLETE_IO:
		storvsc_on_io_completion(device, vstor_packet, request);
		break;

	case VSTOR_OPERATION_REMOVE_DEVICE:
	case VSTOR_OPERATION_ENUMERATE_BUS:
		stor_device = get_in_stor_device(device);
		work = kmalloc(sizeof(struct storvsc_scan_work), GFP_ATOMIC);
		if (!work)
			return;

		INIT_WORK(&work->work, storvsc_bus_scan);
		work->host = stor_device->host;
		schedule_work(&work->work);
		break;

	default:
		break;
	}
}

static void storvsc_on_channel_callback(void *context)
{
	struct vmbus_channel *channel = (struct vmbus_channel *)context;
	struct hv_device *device;
	struct storvsc_device *stor_device;
	u32 bytes_recvd;
	u64 request_id;
	unsigned char packet[ALIGN(sizeof(struct vstor_packet), 8)];
	struct storvsc_cmd_request *request;
	int ret;

	if (channel->primary_channel != NULL)
		device = channel->primary_channel->device_obj;
	else
		device = channel->device_obj;

	stor_device = get_in_stor_device(device);
	if (!stor_device)
		return;

	do {
		ret = vmbus_recvpacket(channel, packet,
				       ALIGN((sizeof(struct vstor_packet) -
					     vmscsi_size_delta), 8),
				       &bytes_recvd, &request_id);
		if (ret == 0 && bytes_recvd > 0) {

			request = (struct storvsc_cmd_request *)
					(unsigned long)request_id;

			if ((request == &stor_device->init_request) ||
			    (request == &stor_device->reset_request)) {

				memcpy(&request->vstor_packet, packet,
				       (sizeof(struct vstor_packet) -
					vmscsi_size_delta));
				complete(&request->wait_event);
			} else {
				storvsc_on_receive(device,
						(struct vstor_packet *)packet,
						request);
			}
		} else {
			break;
		}
	} while (1);

	return;
}

static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size)
{
	struct vmstorage_channel_properties props;
	int ret;

	memset(&props, 0, sizeof(struct vmstorage_channel_properties));

	ret = vmbus_open(device->channel,
			 ring_size,
			 ring_size,
			 (void *)&props,
			 sizeof(struct vmstorage_channel_properties),
			 storvsc_on_channel_callback, device->channel);

	if (ret != 0)
		return ret;

	ret = storvsc_channel_init(device);

	return ret;
}

static int storvsc_dev_remove(struct hv_device *device)
{
	struct storvsc_device *stor_device;
	unsigned long flags;

	stor_device = hv_get_drvdata(device);

	spin_lock_irqsave(&device->channel->inbound_lock, flags);
	stor_device->destroy = true;
	spin_unlock_irqrestore(&device->channel->inbound_lock, flags);

	/*
	 * At this point, all outbound traffic should be disable. We
	 * only allow inbound traffic (responses) to proceed so that
	 * outstanding requests can be completed.
	 */

	storvsc_wait_to_drain(stor_device);

	/*
	 * Since we have already drained, we don't need to busy wait
	 * as was done in final_release_stor_device()
	 * Note that we cannot set the ext pointer to NULL until
	 * we have drained - to drain the outgoing packets, we need to
	 * allow incoming packets.
	 */
	spin_lock_irqsave(&device->channel->inbound_lock, flags);
	hv_set_drvdata(device, NULL);
	spin_unlock_irqrestore(&device->channel->inbound_lock, flags);

	/* Close the channel */
	vmbus_close(device->channel);

	kfree(stor_device);
	return 0;
}

static int storvsc_do_io(struct hv_device *device,
			      struct storvsc_cmd_request *request)
{
	struct storvsc_device *stor_device;
	struct vstor_packet *vstor_packet;
	struct vmbus_channel *outgoing_channel;
	int ret = 0;

	vstor_packet = &request->vstor_packet;
	stor_device = get_out_stor_device(device);

	if (!stor_device)
		return -ENODEV;


	request->device  = device;
	/*
	 * Select an an appropriate channel to send the request out.
	 */

	outgoing_channel = vmbus_get_outgoing_channel(device->channel);


	vstor_packet->flags |= REQUEST_COMPLETION_FLAG;

	vstor_packet->vm_srb.length = (sizeof(struct vmscsi_request) -
					vmscsi_size_delta);


	vstor_packet->vm_srb.sense_info_length = sense_buffer_size;


	vstor_packet->vm_srb.data_transfer_length =
	request->data_buffer.len;

	vstor_packet->operation = VSTOR_OPERATION_EXECUTE_SRB;

	if (request->data_buffer.len) {
		ret = vmbus_sendpacket_multipagebuffer(outgoing_channel,
				&request->data_buffer,
				vstor_packet,
				(sizeof(struct vstor_packet) -
				vmscsi_size_delta),
				(unsigned long)request);
	} else {
		ret = vmbus_sendpacket(device->channel, vstor_packet,
			       (sizeof(struct vstor_packet) -
				vmscsi_size_delta),
			       (unsigned long)request,
			       VM_PKT_DATA_INBAND,
			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
	}

	if (ret != 0)
		return ret;

	atomic_inc(&stor_device->num_outstanding_req);

	return ret;
}

static int storvsc_device_alloc(struct scsi_device *sdevice)
{
	struct stor_mem_pools *memp;
	int number = STORVSC_MIN_BUF_NR;

	memp = kzalloc(sizeof(struct stor_mem_pools), GFP_KERNEL);
	if (!memp)
		return -ENOMEM;

	memp->request_pool =
		kmem_cache_create(dev_name(&sdevice->sdev_dev),
				sizeof(struct storvsc_cmd_request), 0,
				SLAB_HWCACHE_ALIGN, NULL);

	if (!memp->request_pool)
		goto err0;

	memp->request_mempool = mempool_create(number, mempool_alloc_slab,
						mempool_free_slab,
						memp->request_pool);

	if (!memp->request_mempool)
		goto err1;

	sdevice->hostdata = memp;

	return 0;

err1:
	kmem_cache_destroy(memp->request_pool);

err0:
	kfree(memp);
	return -ENOMEM;
}

static void storvsc_device_destroy(struct scsi_device *sdevice)
{
	struct stor_mem_pools *memp = sdevice->hostdata;

	mempool_destroy(memp->request_mempool);
	kmem_cache_destroy(memp->request_pool);
	kfree(memp);
	sdevice->hostdata = NULL;
}

static int storvsc_device_configure(struct scsi_device *sdevice)
{
	scsi_adjust_queue_depth(sdevice, MSG_SIMPLE_TAG,
				STORVSC_MAX_IO_REQUESTS);

	blk_queue_max_segment_size(sdevice->request_queue, PAGE_SIZE);

	blk_queue_bounce_limit(sdevice->request_queue, BLK_BOUNCE_ANY);

	blk_queue_rq_timeout(sdevice->request_queue, (storvsc_timeout * HZ));

	sdevice->no_write_same = 1;

	return 0;
}

static int storvsc_get_chs(struct scsi_device *sdev, struct block_device * bdev,
			   sector_t capacity, int *info)
{
	sector_t nsect = capacity;
	sector_t cylinders = nsect;
	int heads, sectors_pt;

	/*
	 * We are making up these values; let us keep it simple.
	 */
	heads = 0xff;
	sectors_pt = 0x3f;      /* Sectors per track */
	sector_div(cylinders, heads * sectors_pt);
	if ((sector_t)(cylinders + 1) * heads * sectors_pt < nsect)
		cylinders = 0xffff;

	info[0] = heads;
	info[1] = sectors_pt;
	info[2] = (int)cylinders;

	return 0;
}

static int storvsc_host_reset_handler(struct scsi_cmnd *scmnd)
{
	struct hv_host_device *host_dev = shost_priv(scmnd->device->host);
	struct hv_device *device = host_dev->dev;

	struct storvsc_device *stor_device;
	struct storvsc_cmd_request *request;
	struct vstor_packet *vstor_packet;
	int ret, t;


	stor_device = get_out_stor_device(device);
	if (!stor_device)
		return FAILED;

	request = &stor_device->reset_request;
	vstor_packet = &request->vstor_packet;

	init_completion(&request->wait_event);

	vstor_packet->operation = VSTOR_OPERATION_RESET_BUS;
	vstor_packet->flags = REQUEST_COMPLETION_FLAG;
	vstor_packet->vm_srb.path_id = stor_device->path_id;

	ret = vmbus_sendpacket(device->channel, vstor_packet,
			       (sizeof(struct vstor_packet) -
				vmscsi_size_delta),
			       (unsigned long)&stor_device->reset_request,
			       VM_PKT_DATA_INBAND,
			       VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
	if (ret != 0)
		return FAILED;

	t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
	if (t == 0)
		return TIMEOUT_ERROR;


	/*
	 * At this point, all outstanding requests in the adapter
	 * should have been flushed out and return to us
	 * There is a potential race here where the host may be in
	 * the process of responding when we return from here.
	 * Just wait for all in-transit packets to be accounted for
	 * before we return from here.
	 */
	storvsc_wait_to_drain(stor_device);

	return SUCCESS;
}

static bool storvsc_scsi_cmd_ok(struct scsi_cmnd *scmnd)
{
	bool allowed = true;
	u8 scsi_op = scmnd->cmnd[0];

	switch (scsi_op) {
	/* the host does not handle WRITE_SAME, log accident usage */
	case WRITE_SAME:
	/*
	 * smartd sends this command and the host does not handle
	 * this. So, don't send it.
	 */
	case SET_WINDOW:
		scmnd->result = ILLEGAL_REQUEST << 16;
		allowed = false;
		break;
	default:
		break;
	}
	return allowed;
}

static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
{
	int ret;
	struct hv_host_device *host_dev = shost_priv(host);
	struct hv_device *dev = host_dev->dev;
	struct storvsc_cmd_request *cmd_request;
	unsigned int request_size = 0;
	int i;
	struct scatterlist *sgl;
	unsigned int sg_count = 0;
	struct vmscsi_request *vm_srb;
	struct stor_mem_pools *memp = scmnd->device->hostdata;

	if (!storvsc_scsi_cmd_ok(scmnd)) {
		scmnd->scsi_done(scmnd);
		return 0;
	}

	request_size = sizeof(struct storvsc_cmd_request);

	cmd_request = mempool_alloc(memp->request_mempool,
				       GFP_ATOMIC);

	/*
	 * We might be invoked in an interrupt context; hence
	 * mempool_alloc() can fail.
	 */
	if (!cmd_request)
		return SCSI_MLQUEUE_DEVICE_BUSY;

	memset(cmd_request, 0, sizeof(struct storvsc_cmd_request));

	/* Setup the cmd request */
	cmd_request->cmd = scmnd;

	scmnd->host_scribble = (unsigned char *)cmd_request;

	vm_srb = &cmd_request->vstor_packet.vm_srb;
	vm_srb->win8_extension.time_out_value = 60;


	/* Build the SRB */
	switch (scmnd->sc_data_direction) {
	case DMA_TO_DEVICE:
		vm_srb->data_in = WRITE_TYPE;
		vm_srb->win8_extension.srb_flags |= SRB_FLAGS_DATA_OUT;
		vm_srb->win8_extension.srb_flags |=
			(SRB_FLAGS_QUEUE_ACTION_ENABLE |
			SRB_FLAGS_DISABLE_SYNCH_TRANSFER);
		break;
	case DMA_FROM_DEVICE:
		vm_srb->data_in = READ_TYPE;
		vm_srb->win8_extension.srb_flags |= SRB_FLAGS_DATA_IN;
		vm_srb->win8_extension.srb_flags |=
			(SRB_FLAGS_QUEUE_ACTION_ENABLE |
			SRB_FLAGS_DISABLE_SYNCH_TRANSFER);
		break;
	default:
		vm_srb->data_in = UNKNOWN_TYPE;
		vm_srb->win8_extension.srb_flags = 0;
		break;
	}


	vm_srb->port_number = host_dev->port;
	vm_srb->path_id = scmnd->device->channel;
	vm_srb->target_id = scmnd->device->id;
	vm_srb->lun = scmnd->device->lun;

	vm_srb->cdb_length = scmnd->cmd_len;

	memcpy(vm_srb->cdb, scmnd->cmnd, vm_srb->cdb_length);

	cmd_request->sense_buffer = scmnd->sense_buffer;


	cmd_request->data_buffer.len = scsi_bufflen(scmnd);
	if (scsi_sg_count(scmnd)) {
		sgl = (struct scatterlist *)scsi_sglist(scmnd);
		sg_count = scsi_sg_count(scmnd);

		/* check if we need to bounce the sgl */
		if (do_bounce_buffer(sgl, scsi_sg_count(scmnd)) != -1) {
			cmd_request->bounce_sgl =
				create_bounce_buffer(sgl, scsi_sg_count(scmnd),
						     scsi_bufflen(scmnd),
						     vm_srb->data_in);
			if (!cmd_request->bounce_sgl) {
				ret = SCSI_MLQUEUE_HOST_BUSY;
				goto queue_error;
			}

			cmd_request->bounce_sgl_count =
				ALIGN(scsi_bufflen(scmnd), PAGE_SIZE) >>
					PAGE_SHIFT;

			if (vm_srb->data_in == WRITE_TYPE)
				copy_to_bounce_buffer(sgl,
					cmd_request->bounce_sgl,
					scsi_sg_count(scmnd));

			sgl = cmd_request->bounce_sgl;
			sg_count = cmd_request->bounce_sgl_count;
		}

		cmd_request->data_buffer.offset = sgl[0].offset;

		for (i = 0; i < sg_count; i++)
			cmd_request->data_buffer.pfn_array[i] =
				page_to_pfn(sg_page((&sgl[i])));

	} else if (scsi_sglist(scmnd)) {
		cmd_request->data_buffer.offset =
			virt_to_phys(scsi_sglist(scmnd)) & (PAGE_SIZE-1);
		cmd_request->data_buffer.pfn_array[0] =
			virt_to_phys(scsi_sglist(scmnd)) >> PAGE_SHIFT;
	}

	/* Invokes the vsc to start an IO */
	ret = storvsc_do_io(dev, cmd_request);

	if (ret == -EAGAIN) {
		/* no more space */

		if (cmd_request->bounce_sgl_count) {
			destroy_bounce_buffer(cmd_request->bounce_sgl,
					cmd_request->bounce_sgl_count);

			ret = SCSI_MLQUEUE_DEVICE_BUSY;
			goto queue_error;
		}
	}

	return 0;

queue_error:
	mempool_free(cmd_request, memp->request_mempool);
	scmnd->host_scribble = NULL;
	return ret;
}

static struct scsi_host_template scsi_driver = {
	.module	=		THIS_MODULE,
	.name =			"storvsc_host_t",
	.bios_param =		storvsc_get_chs,
	.queuecommand =		storvsc_queuecommand,
	.eh_host_reset_handler =	storvsc_host_reset_handler,
	.slave_alloc =		storvsc_device_alloc,
	.slave_destroy =	storvsc_device_destroy,
	.slave_configure =	storvsc_device_configure,
	.cmd_per_lun =		1,
	/* 64 max_queue * 1 target */
	.can_queue =		STORVSC_MAX_IO_REQUESTS*STORVSC_MAX_TARGETS,
	.this_id =		-1,
	/* no use setting to 0 since ll_blk_rw reset it to 1 */
	/* currently 32 */
	.sg_tablesize =		MAX_MULTIPAGE_BUFFER_COUNT,
	.use_clustering =	DISABLE_CLUSTERING,
	/* Make sure we dont get a sg segment crosses a page boundary */
	.dma_boundary =		PAGE_SIZE-1,
	.no_write_same =	1,
};

enum {
	SCSI_GUID,
	IDE_GUID,
	SFC_GUID,
};

static const struct hv_vmbus_device_id id_table[] = {
	/* SCSI guid */
	{ HV_SCSI_GUID,
	  .driver_data = SCSI_GUID
	},
	/* IDE guid */
	{ HV_IDE_GUID,
	  .driver_data = IDE_GUID
	},
	/* Fibre Channel GUID */
	{
	  HV_SYNTHFC_GUID,
	  .driver_data = SFC_GUID
	},
	{ },
};

MODULE_DEVICE_TABLE(vmbus, id_table);

static int storvsc_probe(struct hv_device *device,
			const struct hv_vmbus_device_id *dev_id)
{
	int ret;
	struct Scsi_Host *host;
	struct hv_host_device *host_dev;
	bool dev_is_ide = ((dev_id->driver_data == IDE_GUID) ? true : false);
	int target = 0;
	struct storvsc_device *stor_device;

	/*
	 * Based on the windows host we are running on,
	 * set state to properly communicate with the host.
	 */

	if (vmbus_proto_version == VERSION_WIN8) {
		sense_buffer_size = POST_WIN7_STORVSC_SENSE_BUFFER_SIZE;
		vmscsi_size_delta = 0;
		vmstor_current_major = VMSTOR_WIN8_MAJOR;
		vmstor_current_minor = VMSTOR_WIN8_MINOR;
	} else {
		sense_buffer_size = PRE_WIN8_STORVSC_SENSE_BUFFER_SIZE;
		vmscsi_size_delta = sizeof(struct vmscsi_win8_extension);
		vmstor_current_major = VMSTOR_WIN7_MAJOR;
		vmstor_current_minor = VMSTOR_WIN7_MINOR;
	}


	host = scsi_host_alloc(&scsi_driver,
			       sizeof(struct hv_host_device));
	if (!host)
		return -ENOMEM;

	host_dev = shost_priv(host);
	memset(host_dev, 0, sizeof(struct hv_host_device));

	host_dev->port = host->host_no;
	host_dev->dev = device;


	stor_device = kzalloc(sizeof(struct storvsc_device), GFP_KERNEL);
	if (!stor_device) {
		ret = -ENOMEM;
		goto err_out0;
	}

	stor_device->destroy = false;
	stor_device->open_sub_channel = false;
	init_waitqueue_head(&stor_device->waiting_to_drain);
	stor_device->device = device;
	stor_device->host = host;
	hv_set_drvdata(device, stor_device);

	stor_device->port_number = host->host_no;
	ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size);
	if (ret)
		goto err_out1;

	host_dev->path = stor_device->path_id;
	host_dev->target = stor_device->target_id;

	/* max # of devices per target */
	host->max_lun = STORVSC_MAX_LUNS_PER_TARGET;
	/* max # of targets per channel */
	host->max_id = STORVSC_MAX_TARGETS;
	/* max # of channels */
	host->max_channel = STORVSC_MAX_CHANNELS - 1;
	/* max cmd length */
	host->max_cmd_len = STORVSC_MAX_CMD_LEN;

	/* Register the HBA and start the scsi bus scan */
	ret = scsi_add_host(host, &device->device);
	if (ret != 0)
		goto err_out2;

	if (!dev_is_ide) {
		scsi_scan_host(host);
	} else {
		target = (device->dev_instance.b[5] << 8 |
			 device->dev_instance.b[4]);
		ret = scsi_add_device(host, 0, target, 0);
		if (ret) {
			scsi_remove_host(host);
			goto err_out2;
		}
	}
	return 0;

err_out2:
	/*
	 * Once we have connected with the host, we would need to
	 * to invoke storvsc_dev_remove() to rollback this state and
	 * this call also frees up the stor_device; hence the jump around
	 * err_out1 label.
	 */
	storvsc_dev_remove(device);
	goto err_out0;

err_out1:
	kfree(stor_device);

err_out0:
	scsi_host_put(host);
	return ret;
}

static int storvsc_remove(struct hv_device *dev)
{
	struct storvsc_device *stor_device = hv_get_drvdata(dev);
	struct Scsi_Host *host = stor_device->host;

	scsi_remove_host(host);
	storvsc_dev_remove(dev);
	scsi_host_put(host);

	return 0;
}

static struct hv_driver storvsc_drv = {
	.name = KBUILD_MODNAME,
	.id_table = id_table,
	.probe = storvsc_probe,
	.remove = storvsc_remove,
};

static int __init storvsc_drv_init(void)
{
	u32 max_outstanding_req_per_channel;

	/*
	 * Divide the ring buffer data size (which is 1 page less
	 * than the ring buffer size since that page is reserved for
	 * the ring buffer indices) by the max request size (which is
	 * vmbus_channel_packet_multipage_buffer + struct vstor_packet + u64)
	 */
	max_outstanding_req_per_channel =
		((storvsc_ringbuffer_size - PAGE_SIZE) /
		ALIGN(MAX_MULTIPAGE_BUFFER_PACKET +
		sizeof(struct vstor_packet) + sizeof(u64) -
		vmscsi_size_delta,
		sizeof(u64)));

	if (max_outstanding_req_per_channel <
	    STORVSC_MAX_IO_REQUESTS)
		return -EINVAL;

	return vmbus_driver_register(&storvsc_drv);
}

static void __exit storvsc_drv_exit(void)
{
	vmbus_driver_unregister(&storvsc_drv);
}

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Microsoft Hyper-V virtual storage driver");
module_init(storvsc_drv_init);
module_exit(storvsc_drv_exit);