summaryrefslogtreecommitdiff
path: root/drivers/scsi/iscsi_tcp.c
blob: 8cdcaf33fb4e227d58d22367f7f36cd1913ae9a2 (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
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
/*
 * iSCSI Initiator over TCP/IP Data-Path
 *
 * Copyright (C) 2004 Dmitry Yusupov
 * Copyright (C) 2004 Alex Aizman
 * Copyright (C) 2005 - 2006 Mike Christie
 * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
 * maintained by open-iscsi@googlegroups.com
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that 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.
 *
 * See the file COPYING included with this distribution for more details.
 *
 * Credits:
 *	Christoph Hellwig
 *	FUJITA Tomonori
 *	Arne Redlich
 *	Zhenyu Wang
 */

#include <linux/types.h>
#include <linux/list.h>
#include <linux/inet.h>
#include <linux/file.h>
#include <linux/blkdev.h>
#include <linux/crypto.h>
#include <linux/delay.h>
#include <linux/kfifo.h>
#include <linux/scatterlist.h>
#include <net/tcp.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi.h>
#include <scsi/scsi_transport_iscsi.h>

#include "iscsi_tcp.h"

MODULE_AUTHOR("Dmitry Yusupov <dmitry_yus@yahoo.com>, "
	      "Alex Aizman <itn780@yahoo.com>");
MODULE_DESCRIPTION("iSCSI/TCP data-path");
MODULE_LICENSE("GPL");
#undef DEBUG_TCP
#define DEBUG_ASSERT

#ifdef DEBUG_TCP
#define debug_tcp(fmt...) printk(KERN_INFO "tcp: " fmt)
#else
#define debug_tcp(fmt...)
#endif

#ifndef DEBUG_ASSERT
#ifdef BUG_ON
#undef BUG_ON
#endif
#define BUG_ON(expr)
#endif

static struct scsi_transport_template *iscsi_tcp_scsi_transport;
static struct scsi_host_template iscsi_sht;
static struct iscsi_transport iscsi_tcp_transport;

static unsigned int iscsi_max_lun = 512;
module_param_named(max_lun, iscsi_max_lun, uint, S_IRUGO);

static int iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
				   struct iscsi_segment *segment);

/*
 * Scatterlist handling: inside the iscsi_segment, we
 * remember an index into the scatterlist, and set data/size
 * to the current scatterlist entry. For highmem pages, we
 * kmap as needed.
 *
 * Note that the page is unmapped when we return from
 * TCP's data_ready handler, so we may end up mapping and
 * unmapping the same page repeatedly. The whole reason
 * for this is that we shouldn't keep the page mapped
 * outside the softirq.
 */

/**
 * iscsi_tcp_segment_init_sg - init indicated scatterlist entry
 * @segment: the buffer object
 * @sg: scatterlist
 * @offset: byte offset into that sg entry
 *
 * This function sets up the segment so that subsequent
 * data is copied to the indicated sg entry, at the given
 * offset.
 */
static inline void
iscsi_tcp_segment_init_sg(struct iscsi_segment *segment,
			  struct scatterlist *sg, unsigned int offset)
{
	segment->sg = sg;
	segment->sg_offset = offset;
	segment->size = min(sg->length - offset,
			    segment->total_size - segment->total_copied);
	segment->data = NULL;
}

/**
 * iscsi_tcp_segment_map - map the current S/G page
 * @segment: iscsi_segment
 * @recv: 1 if called from recv path
 *
 * We only need to possibly kmap data if scatter lists are being used,
 * because the iscsi passthrough and internal IO paths will never use high
 * mem pages.
 */
static inline void
iscsi_tcp_segment_map(struct iscsi_segment *segment, int recv)
{
	struct scatterlist *sg;

	if (segment->data != NULL || !segment->sg)
		return;

	sg = segment->sg;
	BUG_ON(segment->sg_mapped);
	BUG_ON(sg->length == 0);

	/*
	 * If the page count is greater than one it is ok to send
	 * to the network layer's zero copy send path. If not we
	 * have to go the slow sendmsg path. We always map for the
	 * recv path.
	 */
	if (page_count(sg_page(sg)) >= 1 && !recv)
		return;

	debug_tcp("iscsi_tcp_segment_map %s %p\n", recv ? "recv" : "xmit",
		  segment);
	segment->sg_mapped = kmap_atomic(sg_page(sg), KM_SOFTIRQ0);
	segment->data = segment->sg_mapped + sg->offset + segment->sg_offset;
}

static inline void
iscsi_tcp_segment_unmap(struct iscsi_segment *segment)
{
	debug_tcp("iscsi_tcp_segment_unmap %p\n", segment);

	if (segment->sg_mapped) {
		debug_tcp("iscsi_tcp_segment_unmap valid\n");
		kunmap_atomic(segment->sg_mapped, KM_SOFTIRQ0);
		segment->sg_mapped = NULL;
		segment->data = NULL;
	}
}

/*
 * Splice the digest buffer into the buffer
 */
static inline void
iscsi_tcp_segment_splice_digest(struct iscsi_segment *segment, void *digest)
{
	segment->data = digest;
	segment->digest_len = ISCSI_DIGEST_SIZE;
	segment->total_size += ISCSI_DIGEST_SIZE;
	segment->size = ISCSI_DIGEST_SIZE;
	segment->copied = 0;
	segment->sg = NULL;
	segment->hash = NULL;
}

/**
 * iscsi_tcp_segment_done - check whether the segment is complete
 * @segment: iscsi segment to check
 * @recv: set to one of this is called from the recv path
 * @copied: number of bytes copied
 *
 * Check if we're done receiving this segment. If the receive
 * buffer is full but we expect more data, move on to the
 * next entry in the scatterlist.
 *
 * If the amount of data we received isn't a multiple of 4,
 * we will transparently receive the pad bytes, too.
 *
 * This function must be re-entrant.
 */
static inline int
iscsi_tcp_segment_done(struct iscsi_segment *segment, int recv, unsigned copied)
{
	static unsigned char padbuf[ISCSI_PAD_LEN];
	struct scatterlist sg;
	unsigned int pad;

	debug_tcp("copied %u %u size %u %s\n", segment->copied, copied,
		  segment->size, recv ? "recv" : "xmit");
	if (segment->hash && copied) {
		/*
		 * If a segment is kmapd we must unmap it before sending
		 * to the crypto layer since that will try to kmap it again.
		 */
		iscsi_tcp_segment_unmap(segment);

		if (!segment->data) {
			sg_init_table(&sg, 1);
			sg_set_page(&sg, sg_page(segment->sg), copied,
				    segment->copied + segment->sg_offset +
							segment->sg->offset);
		} else
			sg_init_one(&sg, segment->data + segment->copied,
				    copied);
		crypto_hash_update(segment->hash, &sg, copied);
	}

	segment->copied += copied;
	if (segment->copied < segment->size) {
		iscsi_tcp_segment_map(segment, recv);
		return 0;
	}

	segment->total_copied += segment->copied;
	segment->copied = 0;
	segment->size = 0;

	/* Unmap the current scatterlist page, if there is one. */
	iscsi_tcp_segment_unmap(segment);

	/* Do we have more scatterlist entries? */
	debug_tcp("total copied %u total size %u\n", segment->total_copied,
		   segment->total_size);
	if (segment->total_copied < segment->total_size) {
		/* Proceed to the next entry in the scatterlist. */
		iscsi_tcp_segment_init_sg(segment, sg_next(segment->sg),
					  0);
		iscsi_tcp_segment_map(segment, recv);
		BUG_ON(segment->size == 0);
		return 0;
	}

	/* Do we need to handle padding? */
	pad = iscsi_padding(segment->total_copied);
	if (pad != 0) {
		debug_tcp("consume %d pad bytes\n", pad);
		segment->total_size += pad;
		segment->size = pad;
		segment->data = padbuf;
		return 0;
	}

	/*
	 * Set us up for transferring the data digest. hdr digest
	 * is completely handled in hdr done function.
	 */
	if (segment->hash) {
		crypto_hash_final(segment->hash, segment->digest);
		iscsi_tcp_segment_splice_digest(segment,
				 recv ? segment->recv_digest : segment->digest);
		return 0;
	}

	return 1;
}

/**
 * iscsi_tcp_xmit_segment - transmit segment
 * @tcp_conn: the iSCSI TCP connection
 * @segment: the buffer to transmnit
 *
 * This function transmits as much of the buffer as
 * the network layer will accept, and returns the number of
 * bytes transmitted.
 *
 * If CRC hashing is enabled, the function will compute the
 * hash as it goes. When the entire segment has been transmitted,
 * it will retrieve the hash value and send it as well.
 */
static int
iscsi_tcp_xmit_segment(struct iscsi_tcp_conn *tcp_conn,
		       struct iscsi_segment *segment)
{
	struct socket *sk = tcp_conn->sock;
	unsigned int copied = 0;
	int r = 0;

	while (!iscsi_tcp_segment_done(segment, 0, r)) {
		struct scatterlist *sg;
		unsigned int offset, copy;
		int flags = 0;

		r = 0;
		offset = segment->copied;
		copy = segment->size - offset;

		if (segment->total_copied + segment->size < segment->total_size)
			flags |= MSG_MORE;

		/* Use sendpage if we can; else fall back to sendmsg */
		if (!segment->data) {
			sg = segment->sg;
			offset += segment->sg_offset + sg->offset;
			r = tcp_conn->sendpage(sk, sg_page(sg), offset, copy,
					       flags);
		} else {
			struct msghdr msg = { .msg_flags = flags };
			struct kvec iov = {
				.iov_base = segment->data + offset,
				.iov_len = copy
			};

			r = kernel_sendmsg(sk, &msg, &iov, 1, copy);
		}

		if (r < 0) {
			iscsi_tcp_segment_unmap(segment);
			if (copied || r == -EAGAIN)
				break;
			return r;
		}
		copied += r;
	}
	return copied;
}

/**
 * iscsi_tcp_segment_recv - copy data to segment
 * @tcp_conn: the iSCSI TCP connection
 * @segment: the buffer to copy to
 * @ptr: data pointer
 * @len: amount of data available
 *
 * This function copies up to @len bytes to the
 * given buffer, and returns the number of bytes
 * consumed, which can actually be less than @len.
 *
 * If hash digest is enabled, the function will update the
 * hash while copying.
 * Combining these two operations doesn't buy us a lot (yet),
 * but in the future we could implement combined copy+crc,
 * just way we do for network layer checksums.
 */
static int
iscsi_tcp_segment_recv(struct iscsi_tcp_conn *tcp_conn,
		       struct iscsi_segment *segment, const void *ptr,
		       unsigned int len)
{
	unsigned int copy = 0, copied = 0;

	while (!iscsi_tcp_segment_done(segment, 1, copy)) {
		if (copied == len) {
			debug_tcp("iscsi_tcp_segment_recv copied %d bytes\n",
				  len);
			break;
		}

		copy = min(len - copied, segment->size - segment->copied);
		debug_tcp("iscsi_tcp_segment_recv copying %d\n", copy);
		memcpy(segment->data + segment->copied, ptr + copied, copy);
		copied += copy;
	}
	return copied;
}

static inline void
iscsi_tcp_dgst_header(struct hash_desc *hash, const void *hdr, size_t hdrlen,
		      unsigned char digest[ISCSI_DIGEST_SIZE])
{
	struct scatterlist sg;

	sg_init_one(&sg, hdr, hdrlen);
	crypto_hash_digest(hash, &sg, hdrlen, digest);
}

static inline int
iscsi_tcp_dgst_verify(struct iscsi_tcp_conn *tcp_conn,
		      struct iscsi_segment *segment)
{
	if (!segment->digest_len)
		return 1;

	if (memcmp(segment->recv_digest, segment->digest,
		   segment->digest_len)) {
		debug_scsi("digest mismatch\n");
		return 0;
	}

	return 1;
}

/*
 * Helper function to set up segment buffer
 */
static inline void
__iscsi_segment_init(struct iscsi_segment *segment, size_t size,
		     iscsi_segment_done_fn_t *done, struct hash_desc *hash)
{
	memset(segment, 0, sizeof(*segment));
	segment->total_size = size;
	segment->done = done;

	if (hash) {
		segment->hash = hash;
		crypto_hash_init(hash);
	}
}

static inline void
iscsi_segment_init_linear(struct iscsi_segment *segment, void *data,
			  size_t size, iscsi_segment_done_fn_t *done,
			  struct hash_desc *hash)
{
	__iscsi_segment_init(segment, size, done, hash);
	segment->data = data;
	segment->size = size;
}

static inline int
iscsi_segment_seek_sg(struct iscsi_segment *segment,
		      struct scatterlist *sg_list, unsigned int sg_count,
		      unsigned int offset, size_t size,
		      iscsi_segment_done_fn_t *done, struct hash_desc *hash)
{
	struct scatterlist *sg;
	unsigned int i;

	debug_scsi("iscsi_segment_seek_sg offset %u size %llu\n",
		  offset, size);
	__iscsi_segment_init(segment, size, done, hash);
	for_each_sg(sg_list, sg, sg_count, i) {
		debug_scsi("sg %d, len %u offset %u\n", i, sg->length,
			   sg->offset);
		if (offset < sg->length) {
			iscsi_tcp_segment_init_sg(segment, sg, offset);
			return 0;
		}
		offset -= sg->length;
	}

	return ISCSI_ERR_DATA_OFFSET;
}

/**
 * iscsi_tcp_hdr_recv_prep - prep segment for hdr reception
 * @tcp_conn: iscsi connection to prep for
 *
 * This function always passes NULL for the hash argument, because when this
 * function is called we do not yet know the final size of the header and want
 * to delay the digest processing until we know that.
 */
static void
iscsi_tcp_hdr_recv_prep(struct iscsi_tcp_conn *tcp_conn)
{
	debug_tcp("iscsi_tcp_hdr_recv_prep(%p%s)\n", tcp_conn,
		  tcp_conn->iscsi_conn->hdrdgst_en ? ", digest enabled" : "");
	iscsi_segment_init_linear(&tcp_conn->in.segment,
				tcp_conn->in.hdr_buf, sizeof(struct iscsi_hdr),
				iscsi_tcp_hdr_recv_done, NULL);
}

/*
 * Handle incoming reply to any other type of command
 */
static int
iscsi_tcp_data_recv_done(struct iscsi_tcp_conn *tcp_conn,
			 struct iscsi_segment *segment)
{
	struct iscsi_conn *conn = tcp_conn->iscsi_conn;
	int rc = 0;

	if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
		return ISCSI_ERR_DATA_DGST;

	rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr,
			conn->data, tcp_conn->in.datalen);
	if (rc)
		return rc;

	iscsi_tcp_hdr_recv_prep(tcp_conn);
	return 0;
}

static void
iscsi_tcp_data_recv_prep(struct iscsi_tcp_conn *tcp_conn)
{
	struct iscsi_conn *conn = tcp_conn->iscsi_conn;
	struct hash_desc *rx_hash = NULL;

	if (conn->datadgst_en)
		rx_hash = &tcp_conn->rx_hash;

	iscsi_segment_init_linear(&tcp_conn->in.segment,
				conn->data, tcp_conn->in.datalen,
				iscsi_tcp_data_recv_done, rx_hash);
}

/*
 * must be called with session lock
 */
static void
iscsi_tcp_cleanup_ctask(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
{
	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
	struct iscsi_r2t_info *r2t;

	/* flush ctask's r2t queues */
	while (__kfifo_get(tcp_ctask->r2tqueue, (void*)&r2t, sizeof(void*))) {
		__kfifo_put(tcp_ctask->r2tpool.queue, (void*)&r2t,
			    sizeof(void*));
		debug_scsi("iscsi_tcp_cleanup_ctask pending r2t dropped\n");
	}

	r2t = tcp_ctask->r2t;
	if (r2t != NULL) {
		__kfifo_put(tcp_ctask->r2tpool.queue, (void*)&r2t,
			    sizeof(void*));
		tcp_ctask->r2t = NULL;
	}
}

/**
 * iscsi_data_rsp - SCSI Data-In Response processing
 * @conn: iscsi connection
 * @ctask: scsi command task
 **/
static int
iscsi_data_rsp(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
{
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
	struct iscsi_data_rsp *rhdr = (struct iscsi_data_rsp *)tcp_conn->in.hdr;
	struct iscsi_session *session = conn->session;
	struct scsi_cmnd *sc = ctask->sc;
	int datasn = be32_to_cpu(rhdr->datasn);
	unsigned total_in_length = scsi_in(sc)->length;

	iscsi_update_cmdsn(session, (struct iscsi_nopin*)rhdr);
	if (tcp_conn->in.datalen == 0)
		return 0;

	if (tcp_ctask->exp_datasn != datasn) {
		debug_tcp("%s: ctask->exp_datasn(%d) != rhdr->datasn(%d)\n",
		          __FUNCTION__, tcp_ctask->exp_datasn, datasn);
		return ISCSI_ERR_DATASN;
	}

	tcp_ctask->exp_datasn++;

	tcp_ctask->data_offset = be32_to_cpu(rhdr->offset);
	if (tcp_ctask->data_offset + tcp_conn->in.datalen > total_in_length) {
		debug_tcp("%s: data_offset(%d) + data_len(%d) > total_length_in(%d)\n",
		          __FUNCTION__, tcp_ctask->data_offset,
		          tcp_conn->in.datalen, total_in_length);
		return ISCSI_ERR_DATA_OFFSET;
	}

	if (rhdr->flags & ISCSI_FLAG_DATA_STATUS) {
		sc->result = (DID_OK << 16) | rhdr->cmd_status;
		conn->exp_statsn = be32_to_cpu(rhdr->statsn) + 1;
		if (rhdr->flags & (ISCSI_FLAG_DATA_UNDERFLOW |
		                   ISCSI_FLAG_DATA_OVERFLOW)) {
			int res_count = be32_to_cpu(rhdr->residual_count);

			if (res_count > 0 &&
			    (rhdr->flags & ISCSI_FLAG_CMD_OVERFLOW ||
			     res_count <= total_in_length))
				scsi_in(sc)->resid = res_count;
			else
				sc->result = (DID_BAD_TARGET << 16) |
					rhdr->cmd_status;
		}
	}

	conn->datain_pdus_cnt++;
	return 0;
}

/**
 * iscsi_solicit_data_init - initialize first Data-Out
 * @conn: iscsi connection
 * @ctask: scsi command task
 * @r2t: R2T info
 *
 * Notes:
 *	Initialize first Data-Out within this R2T sequence and finds
 *	proper data_offset within this SCSI command.
 *
 *	This function is called with connection lock taken.
 **/
static void
iscsi_solicit_data_init(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
			struct iscsi_r2t_info *r2t)
{
	struct iscsi_data *hdr;

	hdr = &r2t->dtask.hdr;
	memset(hdr, 0, sizeof(struct iscsi_data));
	hdr->ttt = r2t->ttt;
	hdr->datasn = cpu_to_be32(r2t->solicit_datasn);
	r2t->solicit_datasn++;
	hdr->opcode = ISCSI_OP_SCSI_DATA_OUT;
	memcpy(hdr->lun, ctask->hdr->lun, sizeof(hdr->lun));
	hdr->itt = ctask->hdr->itt;
	hdr->exp_statsn = r2t->exp_statsn;
	hdr->offset = cpu_to_be32(r2t->data_offset);
	if (r2t->data_length > conn->max_xmit_dlength) {
		hton24(hdr->dlength, conn->max_xmit_dlength);
		r2t->data_count = conn->max_xmit_dlength;
		hdr->flags = 0;
	} else {
		hton24(hdr->dlength, r2t->data_length);
		r2t->data_count = r2t->data_length;
		hdr->flags = ISCSI_FLAG_CMD_FINAL;
	}
	conn->dataout_pdus_cnt++;

	r2t->sent = 0;
}

/**
 * iscsi_r2t_rsp - iSCSI R2T Response processing
 * @conn: iscsi connection
 * @ctask: scsi command task
 **/
static int
iscsi_r2t_rsp(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
{
	struct iscsi_r2t_info *r2t;
	struct iscsi_session *session = conn->session;
	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct iscsi_r2t_rsp *rhdr = (struct iscsi_r2t_rsp *)tcp_conn->in.hdr;
	int r2tsn = be32_to_cpu(rhdr->r2tsn);
	int rc;

	if (tcp_conn->in.datalen) {
		iscsi_conn_printk(KERN_ERR, conn,
				  "invalid R2t with datalen %d\n",
				  tcp_conn->in.datalen);
		return ISCSI_ERR_DATALEN;
	}

	if (tcp_ctask->exp_datasn != r2tsn){
		debug_tcp("%s: ctask->exp_datasn(%d) != rhdr->r2tsn(%d)\n",
		          __FUNCTION__, tcp_ctask->exp_datasn, r2tsn);
		return ISCSI_ERR_R2TSN;
	}

	/* fill-in new R2T associated with the task */
	iscsi_update_cmdsn(session, (struct iscsi_nopin*)rhdr);

	if (!ctask->sc || session->state != ISCSI_STATE_LOGGED_IN) {
		iscsi_conn_printk(KERN_INFO, conn,
				  "dropping R2T itt %d in recovery.\n",
				  ctask->itt);
		return 0;
	}

	rc = __kfifo_get(tcp_ctask->r2tpool.queue, (void*)&r2t, sizeof(void*));
	BUG_ON(!rc);

	r2t->exp_statsn = rhdr->statsn;
	r2t->data_length = be32_to_cpu(rhdr->data_length);
	if (r2t->data_length == 0) {
		iscsi_conn_printk(KERN_ERR, conn,
				  "invalid R2T with zero data len\n");
		__kfifo_put(tcp_ctask->r2tpool.queue, (void*)&r2t,
			    sizeof(void*));
		return ISCSI_ERR_DATALEN;
	}

	if (r2t->data_length > session->max_burst)
		debug_scsi("invalid R2T with data len %u and max burst %u."
			   "Attempting to execute request.\n",
			    r2t->data_length, session->max_burst);

	r2t->data_offset = be32_to_cpu(rhdr->data_offset);
	if (r2t->data_offset + r2t->data_length > scsi_out(ctask->sc)->length) {
		iscsi_conn_printk(KERN_ERR, conn,
				  "invalid R2T with data len %u at offset %u "
				  "and total length %d\n", r2t->data_length,
				  r2t->data_offset, scsi_out(ctask->sc)->length);
		__kfifo_put(tcp_ctask->r2tpool.queue, (void*)&r2t,
			    sizeof(void*));
		return ISCSI_ERR_DATALEN;
	}

	r2t->ttt = rhdr->ttt; /* no flip */
	r2t->solicit_datasn = 0;

	iscsi_solicit_data_init(conn, ctask, r2t);

	tcp_ctask->exp_datasn = r2tsn + 1;
	__kfifo_put(tcp_ctask->r2tqueue, (void*)&r2t, sizeof(void*));
	conn->r2t_pdus_cnt++;

	iscsi_requeue_ctask(ctask);
	return 0;
}

/*
 * Handle incoming reply to DataIn command
 */
static int
iscsi_tcp_process_data_in(struct iscsi_tcp_conn *tcp_conn,
			  struct iscsi_segment *segment)
{
	struct iscsi_conn *conn = tcp_conn->iscsi_conn;
	struct iscsi_hdr *hdr = tcp_conn->in.hdr;
	int rc;

	if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
		return ISCSI_ERR_DATA_DGST;

	/* check for non-exceptional status */
	if (hdr->flags & ISCSI_FLAG_DATA_STATUS) {
		rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr, NULL, 0);
		if (rc)
			return rc;
	}

	iscsi_tcp_hdr_recv_prep(tcp_conn);
	return 0;
}

/**
 * iscsi_tcp_hdr_dissect - process PDU header
 * @conn: iSCSI connection
 * @hdr: PDU header
 *
 * This function analyzes the header of the PDU received,
 * and performs several sanity checks. If the PDU is accompanied
 * by data, the receive buffer is set up to copy the incoming data
 * to the correct location.
 */
static int
iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
{
	int rc = 0, opcode, ahslen;
	struct iscsi_session *session = conn->session;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct iscsi_cmd_task *ctask;
	uint32_t itt;

	/* verify PDU length */
	tcp_conn->in.datalen = ntoh24(hdr->dlength);
	if (tcp_conn->in.datalen > conn->max_recv_dlength) {
		iscsi_conn_printk(KERN_ERR, conn,
				  "iscsi_tcp: datalen %d > %d\n",
				  tcp_conn->in.datalen, conn->max_recv_dlength);
		return ISCSI_ERR_DATALEN;
	}

	/* Additional header segments. So far, we don't
	 * process additional headers.
	 */
	ahslen = hdr->hlength << 2;

	opcode = hdr->opcode & ISCSI_OPCODE_MASK;
	/* verify itt (itt encoding: age+cid+itt) */
	rc = iscsi_verify_itt(conn, hdr, &itt);
	if (rc)
		return rc;

	debug_tcp("opcode 0x%x ahslen %d datalen %d\n",
		  opcode, ahslen, tcp_conn->in.datalen);

	switch(opcode) {
	case ISCSI_OP_SCSI_DATA_IN:
		ctask = session->cmds[itt];
		spin_lock(&conn->session->lock);
		rc = iscsi_data_rsp(conn, ctask);
		spin_unlock(&conn->session->lock);
		if (rc)
			return rc;
		if (tcp_conn->in.datalen) {
			struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
			struct hash_desc *rx_hash = NULL;
			struct scsi_data_buffer *sdb = scsi_in(ctask->sc);

			/*
			 * Setup copy of Data-In into the Scsi_Cmnd
			 * Scatterlist case:
			 * We set up the iscsi_segment to point to the next
			 * scatterlist entry to copy to. As we go along,
			 * we move on to the next scatterlist entry and
			 * update the digest per-entry.
			 */
			if (conn->datadgst_en)
				rx_hash = &tcp_conn->rx_hash;

			debug_tcp("iscsi_tcp_begin_data_in(%p, offset=%d, "
				  "datalen=%d)\n", tcp_conn,
				  tcp_ctask->data_offset,
				  tcp_conn->in.datalen);
			return iscsi_segment_seek_sg(&tcp_conn->in.segment,
						     sdb->table.sgl,
						     sdb->table.nents,
						     tcp_ctask->data_offset,
						     tcp_conn->in.datalen,
						     iscsi_tcp_process_data_in,
						     rx_hash);
		}
		/* fall through */
	case ISCSI_OP_SCSI_CMD_RSP:
		if (tcp_conn->in.datalen) {
			iscsi_tcp_data_recv_prep(tcp_conn);
			return 0;
		}
		rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
		break;
	case ISCSI_OP_R2T:
		ctask = session->cmds[itt];
		if (ahslen)
			rc = ISCSI_ERR_AHSLEN;
		else if (ctask->sc->sc_data_direction == DMA_TO_DEVICE) {
			spin_lock(&session->lock);
			rc = iscsi_r2t_rsp(conn, ctask);
			spin_unlock(&session->lock);
		} else
			rc = ISCSI_ERR_PROTO;
		break;
	case ISCSI_OP_LOGIN_RSP:
	case ISCSI_OP_TEXT_RSP:
	case ISCSI_OP_REJECT:
	case ISCSI_OP_ASYNC_EVENT:
		/*
		 * It is possible that we could get a PDU with a buffer larger
		 * than 8K, but there are no targets that currently do this.
		 * For now we fail until we find a vendor that needs it
		 */
		if (ISCSI_DEF_MAX_RECV_SEG_LEN < tcp_conn->in.datalen) {
			iscsi_conn_printk(KERN_ERR, conn,
					  "iscsi_tcp: received buffer of "
					  "len %u but conn buffer is only %u "
					  "(opcode %0x)\n",
					  tcp_conn->in.datalen,
					  ISCSI_DEF_MAX_RECV_SEG_LEN, opcode);
			rc = ISCSI_ERR_PROTO;
			break;
		}

		/* If there's data coming in with the response,
		 * receive it to the connection's buffer.
		 */
		if (tcp_conn->in.datalen) {
			iscsi_tcp_data_recv_prep(tcp_conn);
			return 0;
		}
	/* fall through */
	case ISCSI_OP_LOGOUT_RSP:
	case ISCSI_OP_NOOP_IN:
	case ISCSI_OP_SCSI_TMFUNC_RSP:
		rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
		break;
	default:
		rc = ISCSI_ERR_BAD_OPCODE;
		break;
	}

	if (rc == 0) {
		/* Anything that comes with data should have
		 * been handled above. */
		if (tcp_conn->in.datalen)
			return ISCSI_ERR_PROTO;
		iscsi_tcp_hdr_recv_prep(tcp_conn);
	}

	return rc;
}

/**
 * iscsi_tcp_hdr_recv_done - process PDU header
 *
 * This is the callback invoked when the PDU header has
 * been received. If the header is followed by additional
 * header segments, we go back for more data.
 */
static int
iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
			struct iscsi_segment *segment)
{
	struct iscsi_conn *conn = tcp_conn->iscsi_conn;
	struct iscsi_hdr *hdr;

	/* Check if there are additional header segments
	 * *prior* to computing the digest, because we
	 * may need to go back to the caller for more.
	 */
	hdr = (struct iscsi_hdr *) tcp_conn->in.hdr_buf;
	if (segment->copied == sizeof(struct iscsi_hdr) && hdr->hlength) {
		/* Bump the header length - the caller will
		 * just loop around and get the AHS for us, and
		 * call again. */
		unsigned int ahslen = hdr->hlength << 2;

		/* Make sure we don't overflow */
		if (sizeof(*hdr) + ahslen > sizeof(tcp_conn->in.hdr_buf))
			return ISCSI_ERR_AHSLEN;

		segment->total_size += ahslen;
		segment->size += ahslen;
		return 0;
	}

	/* We're done processing the header. See if we're doing
	 * header digests; if so, set up the recv_digest buffer
	 * and go back for more. */
	if (conn->hdrdgst_en) {
		if (segment->digest_len == 0) {
			iscsi_tcp_segment_splice_digest(segment,
							segment->recv_digest);
			return 0;
		}
		iscsi_tcp_dgst_header(&tcp_conn->rx_hash, hdr,
				      segment->total_copied - ISCSI_DIGEST_SIZE,
				      segment->digest);

		if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
			return ISCSI_ERR_HDR_DGST;
	}

	tcp_conn->in.hdr = hdr;
	return iscsi_tcp_hdr_dissect(conn, hdr);
}

/**
 * iscsi_tcp_recv - TCP receive in sendfile fashion
 * @rd_desc: read descriptor
 * @skb: socket buffer
 * @offset: offset in skb
 * @len: skb->len - offset
 **/
static int
iscsi_tcp_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
	       unsigned int offset, size_t len)
{
	struct iscsi_conn *conn = rd_desc->arg.data;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct iscsi_segment *segment = &tcp_conn->in.segment;
	struct skb_seq_state seq;
	unsigned int consumed = 0;
	int rc = 0;

	debug_tcp("in %d bytes\n", skb->len - offset);

	if (unlikely(conn->suspend_rx)) {
		debug_tcp("conn %d Rx suspended!\n", conn->id);
		return 0;
	}

	skb_prepare_seq_read(skb, offset, skb->len, &seq);
	while (1) {
		unsigned int avail;
		const u8 *ptr;

		avail = skb_seq_read(consumed, &ptr, &seq);
		if (avail == 0) {
			debug_tcp("no more data avail. Consumed %d\n",
				  consumed);
			break;
		}
		BUG_ON(segment->copied >= segment->size);

		debug_tcp("skb %p ptr=%p avail=%u\n", skb, ptr, avail);
		rc = iscsi_tcp_segment_recv(tcp_conn, segment, ptr, avail);
		BUG_ON(rc == 0);
		consumed += rc;

		if (segment->total_copied >= segment->total_size) {
			debug_tcp("segment done\n");
			rc = segment->done(tcp_conn, segment);
			if (rc != 0) {
				skb_abort_seq_read(&seq);
				goto error;
			}

			/* The done() functions sets up the
			 * next segment. */
		}
	}
	skb_abort_seq_read(&seq);
	conn->rxdata_octets += consumed;
	return consumed;

error:
	debug_tcp("Error receiving PDU, errno=%d\n", rc);
	iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
	return 0;
}

static void
iscsi_tcp_data_ready(struct sock *sk, int flag)
{
	struct iscsi_conn *conn = sk->sk_user_data;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	read_descriptor_t rd_desc;

	read_lock(&sk->sk_callback_lock);

	/*
	 * Use rd_desc to pass 'conn' to iscsi_tcp_recv.
	 * We set count to 1 because we want the network layer to
	 * hand us all the skbs that are available. iscsi_tcp_recv
	 * handled pdus that cross buffers or pdus that still need data.
	 */
	rd_desc.arg.data = conn;
	rd_desc.count = 1;
	tcp_read_sock(sk, &rd_desc, iscsi_tcp_recv);

	read_unlock(&sk->sk_callback_lock);

	/* If we had to (atomically) map a highmem page,
	 * unmap it now. */
	iscsi_tcp_segment_unmap(&tcp_conn->in.segment);
}

static void
iscsi_tcp_state_change(struct sock *sk)
{
	struct iscsi_tcp_conn *tcp_conn;
	struct iscsi_conn *conn;
	struct iscsi_session *session;
	void (*old_state_change)(struct sock *);

	read_lock(&sk->sk_callback_lock);

	conn = (struct iscsi_conn*)sk->sk_user_data;
	session = conn->session;

	if ((sk->sk_state == TCP_CLOSE_WAIT ||
	     sk->sk_state == TCP_CLOSE) &&
	    !atomic_read(&sk->sk_rmem_alloc)) {
		debug_tcp("iscsi_tcp_state_change: TCP_CLOSE|TCP_CLOSE_WAIT\n");
		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
	}

	tcp_conn = conn->dd_data;
	old_state_change = tcp_conn->old_state_change;

	read_unlock(&sk->sk_callback_lock);

	old_state_change(sk);
}

/**
 * iscsi_write_space - Called when more output buffer space is available
 * @sk: socket space is available for
 **/
static void
iscsi_write_space(struct sock *sk)
{
	struct iscsi_conn *conn = (struct iscsi_conn*)sk->sk_user_data;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;

	tcp_conn->old_write_space(sk);
	debug_tcp("iscsi_write_space: cid %d\n", conn->id);
	scsi_queue_work(conn->session->host, &conn->xmitwork);
}

static void
iscsi_conn_set_callbacks(struct iscsi_conn *conn)
{
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct sock *sk = tcp_conn->sock->sk;

	/* assign new callbacks */
	write_lock_bh(&sk->sk_callback_lock);
	sk->sk_user_data = conn;
	tcp_conn->old_data_ready = sk->sk_data_ready;
	tcp_conn->old_state_change = sk->sk_state_change;
	tcp_conn->old_write_space = sk->sk_write_space;
	sk->sk_data_ready = iscsi_tcp_data_ready;
	sk->sk_state_change = iscsi_tcp_state_change;
	sk->sk_write_space = iscsi_write_space;
	write_unlock_bh(&sk->sk_callback_lock);
}

static void
iscsi_conn_restore_callbacks(struct iscsi_tcp_conn *tcp_conn)
{
	struct sock *sk = tcp_conn->sock->sk;

	/* restore socket callbacks, see also: iscsi_conn_set_callbacks() */
	write_lock_bh(&sk->sk_callback_lock);
	sk->sk_user_data    = NULL;
	sk->sk_data_ready   = tcp_conn->old_data_ready;
	sk->sk_state_change = tcp_conn->old_state_change;
	sk->sk_write_space  = tcp_conn->old_write_space;
	sk->sk_no_check	 = 0;
	write_unlock_bh(&sk->sk_callback_lock);
}

/**
 * iscsi_xmit - TCP transmit
 **/
static int
iscsi_xmit(struct iscsi_conn *conn)
{
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct iscsi_segment *segment = &tcp_conn->out.segment;
	unsigned int consumed = 0;
	int rc = 0;

	while (1) {
		rc = iscsi_tcp_xmit_segment(tcp_conn, segment);
		if (rc < 0)
			goto error;
		if (rc == 0)
			break;

		consumed += rc;

		if (segment->total_copied >= segment->total_size) {
			if (segment->done != NULL) {
				rc = segment->done(tcp_conn, segment);
				if (rc < 0)
					goto error;
			}
		}
	}

	debug_tcp("xmit %d bytes\n", consumed);

	conn->txdata_octets += consumed;
	return consumed;

error:
	/* Transmit error. We could initiate error recovery
	 * here. */
	debug_tcp("Error sending PDU, errno=%d\n", rc);
	iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
	return rc;
}

/**
 * iscsi_tcp_xmit_qlen - return the number of bytes queued for xmit
 */
static inline int
iscsi_tcp_xmit_qlen(struct iscsi_conn *conn)
{
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct iscsi_segment *segment = &tcp_conn->out.segment;

	return segment->total_copied - segment->total_size;
}

static inline int
iscsi_tcp_flush(struct iscsi_conn *conn)
{
	int rc;

	while (iscsi_tcp_xmit_qlen(conn)) {
		rc = iscsi_xmit(conn);
		if (rc == 0)
			return -EAGAIN;
		if (rc < 0)
			return rc;
	}

	return 0;
}

/*
 * This is called when we're done sending the header.
 * Simply copy the data_segment to the send segment, and return.
 */
static int
iscsi_tcp_send_hdr_done(struct iscsi_tcp_conn *tcp_conn,
			struct iscsi_segment *segment)
{
	tcp_conn->out.segment = tcp_conn->out.data_segment;
	debug_tcp("Header done. Next segment size %u total_size %u\n",
		  tcp_conn->out.segment.size, tcp_conn->out.segment.total_size);
	return 0;
}

static void
iscsi_tcp_send_hdr_prep(struct iscsi_conn *conn, void *hdr, size_t hdrlen)
{
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;

	debug_tcp("%s(%p%s)\n", __FUNCTION__, tcp_conn,
			conn->hdrdgst_en? ", digest enabled" : "");

	/* Clear the data segment - needs to be filled in by the
	 * caller using iscsi_tcp_send_data_prep() */
	memset(&tcp_conn->out.data_segment, 0, sizeof(struct iscsi_segment));

	/* If header digest is enabled, compute the CRC and
	 * place the digest into the same buffer. We make
	 * sure that both iscsi_tcp_ctask and mtask have
	 * sufficient room.
	 */
	if (conn->hdrdgst_en) {
		iscsi_tcp_dgst_header(&tcp_conn->tx_hash, hdr, hdrlen,
				      hdr + hdrlen);
		hdrlen += ISCSI_DIGEST_SIZE;
	}

	/* Remember header pointer for later, when we need
	 * to decide whether there's a payload to go along
	 * with the header. */
	tcp_conn->out.hdr = hdr;

	iscsi_segment_init_linear(&tcp_conn->out.segment, hdr, hdrlen,
				iscsi_tcp_send_hdr_done, NULL);
}

/*
 * Prepare the send buffer for the payload data.
 * Padding and checksumming will all be taken care
 * of by the iscsi_segment routines.
 */
static int
iscsi_tcp_send_data_prep(struct iscsi_conn *conn, struct scatterlist *sg,
			 unsigned int count, unsigned int offset,
			 unsigned int len)
{
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct hash_desc *tx_hash = NULL;
	unsigned int hdr_spec_len;

	debug_tcp("%s(%p, offset=%d, datalen=%d%s)\n", __FUNCTION__,
			tcp_conn, offset, len,
			conn->datadgst_en? ", digest enabled" : "");

	/* Make sure the datalen matches what the caller
	   said he would send. */
	hdr_spec_len = ntoh24(tcp_conn->out.hdr->dlength);
	WARN_ON(iscsi_padded(len) != iscsi_padded(hdr_spec_len));

	if (conn->datadgst_en)
		tx_hash = &tcp_conn->tx_hash;

	return iscsi_segment_seek_sg(&tcp_conn->out.data_segment,
				   sg, count, offset, len,
				   NULL, tx_hash);
}

static void
iscsi_tcp_send_linear_data_prepare(struct iscsi_conn *conn, void *data,
				   size_t len)
{
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct hash_desc *tx_hash = NULL;
	unsigned int hdr_spec_len;

	debug_tcp("%s(%p, datalen=%d%s)\n", __FUNCTION__, tcp_conn, len,
		  conn->datadgst_en? ", digest enabled" : "");

	/* Make sure the datalen matches what the caller
	   said he would send. */
	hdr_spec_len = ntoh24(tcp_conn->out.hdr->dlength);
	WARN_ON(iscsi_padded(len) != iscsi_padded(hdr_spec_len));

	if (conn->datadgst_en)
		tx_hash = &tcp_conn->tx_hash;

	iscsi_segment_init_linear(&tcp_conn->out.data_segment,
				data, len, NULL, tx_hash);
}

/**
 * iscsi_solicit_data_cont - initialize next Data-Out
 * @conn: iscsi connection
 * @ctask: scsi command task
 * @r2t: R2T info
 * @left: bytes left to transfer
 *
 * Notes:
 *	Initialize next Data-Out within this R2T sequence and continue
 *	to process next Scatter-Gather element(if any) of this SCSI command.
 *
 *	Called under connection lock.
 **/
static int
iscsi_solicit_data_cont(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
			struct iscsi_r2t_info *r2t)
{
	struct iscsi_data *hdr;
	int new_offset, left;

	BUG_ON(r2t->data_length - r2t->sent < 0);
	left = r2t->data_length - r2t->sent;
	if (left == 0)
		return 0;

	hdr = &r2t->dtask.hdr;
	memset(hdr, 0, sizeof(struct iscsi_data));
	hdr->ttt = r2t->ttt;
	hdr->datasn = cpu_to_be32(r2t->solicit_datasn);
	r2t->solicit_datasn++;
	hdr->opcode = ISCSI_OP_SCSI_DATA_OUT;
	memcpy(hdr->lun, ctask->hdr->lun, sizeof(hdr->lun));
	hdr->itt = ctask->hdr->itt;
	hdr->exp_statsn = r2t->exp_statsn;
	new_offset = r2t->data_offset + r2t->sent;
	hdr->offset = cpu_to_be32(new_offset);
	if (left > conn->max_xmit_dlength) {
		hton24(hdr->dlength, conn->max_xmit_dlength);
		r2t->data_count = conn->max_xmit_dlength;
	} else {
		hton24(hdr->dlength, left);
		r2t->data_count = left;
		hdr->flags = ISCSI_FLAG_CMD_FINAL;
	}

	conn->dataout_pdus_cnt++;
	return 1;
}

/**
 * iscsi_tcp_ctask - Initialize iSCSI SCSI_READ or SCSI_WRITE commands
 * @conn: iscsi connection
 * @ctask: scsi command task
 * @sc: scsi command
 **/
static int
iscsi_tcp_ctask_init(struct iscsi_cmd_task *ctask)
{
	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
	struct iscsi_conn *conn = ctask->conn;
	struct scsi_cmnd *sc = ctask->sc;
	int err;

	BUG_ON(__kfifo_len(tcp_ctask->r2tqueue));
	tcp_ctask->sent = 0;
	tcp_ctask->exp_datasn = 0;

	/* Prepare PDU, optionally w/ immediate data */
	debug_scsi("ctask deq [cid %d itt 0x%x imm %d unsol %d]\n",
		    conn->id, ctask->itt, ctask->imm_count,
		    ctask->unsol_count);
	iscsi_tcp_send_hdr_prep(conn, ctask->hdr, ctask->hdr_len);

	if (!ctask->imm_count)
		return 0;

	/* If we have immediate data, attach a payload */
	err = iscsi_tcp_send_data_prep(conn, scsi_out(sc)->table.sgl,
				       scsi_out(sc)->table.nents,
				       0, ctask->imm_count);
	if (err)
		return err;
	tcp_ctask->sent += ctask->imm_count;
	ctask->imm_count = 0;
	return 0;
}

/**
 * iscsi_tcp_mtask_xmit - xmit management(immediate) task
 * @conn: iscsi connection
 * @mtask: task management task
 *
 * Notes:
 *	The function can return -EAGAIN in which case caller must
 *	call it again later, or recover. '0' return code means successful
 *	xmit.
 **/
static int
iscsi_tcp_mtask_xmit(struct iscsi_conn *conn, struct iscsi_mgmt_task *mtask)
{
	int rc;

	/* Flush any pending data first. */
	rc = iscsi_tcp_flush(conn);
	if (rc < 0)
		return rc;

	if (mtask->hdr->itt == RESERVED_ITT) {
		struct iscsi_session *session = conn->session;

		spin_lock_bh(&session->lock);
		iscsi_free_mgmt_task(conn, mtask);
		spin_unlock_bh(&session->lock);
	}

	return 0;
}

/*
 * iscsi_tcp_ctask_xmit - xmit normal PDU task
 * @conn: iscsi connection
 * @ctask: iscsi command task
 *
 * We're expected to return 0 when everything was transmitted succesfully,
 * -EAGAIN if there's still data in the queue, or != 0 for any other kind
 * of error.
 */
static int
iscsi_tcp_ctask_xmit(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
{
	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
	struct scsi_cmnd *sc = ctask->sc;
	struct scsi_data_buffer *sdb = scsi_out(sc);
	int rc = 0;

flush:
	/* Flush any pending data first. */
	rc = iscsi_tcp_flush(conn);
	if (rc < 0)
		return rc;

	/* Are we done already? */
	if (sc->sc_data_direction != DMA_TO_DEVICE)
		return 0;

	if (ctask->unsol_count != 0) {
		struct iscsi_data *hdr = &tcp_ctask->unsol_dtask.hdr;

		/* Prepare a header for the unsolicited PDU.
		 * The amount of data we want to send will be
		 * in ctask->data_count.
		 * FIXME: return the data count instead.
		 */
		iscsi_prep_unsolicit_data_pdu(ctask, hdr);

		debug_tcp("unsol dout [itt 0x%x doff %d dlen %d]\n",
				ctask->itt, tcp_ctask->sent, ctask->data_count);

		iscsi_tcp_send_hdr_prep(conn, hdr, sizeof(*hdr));
		rc = iscsi_tcp_send_data_prep(conn, sdb->table.sgl,
					      sdb->table.nents, tcp_ctask->sent,
					      ctask->data_count);
		if (rc)
			goto fail;
		tcp_ctask->sent += ctask->data_count;
		ctask->unsol_count -= ctask->data_count;
		goto flush;
	} else {
		struct iscsi_session *session = conn->session;
		struct iscsi_r2t_info *r2t;

		/* All unsolicited PDUs sent. Check for solicited PDUs.
		 */
		spin_lock_bh(&session->lock);
		r2t = tcp_ctask->r2t;
		if (r2t != NULL) {
			/* Continue with this R2T? */
			if (!iscsi_solicit_data_cont(conn, ctask, r2t)) {
				debug_scsi("  done with r2t %p\n", r2t);

				__kfifo_put(tcp_ctask->r2tpool.queue,
					    (void*)&r2t, sizeof(void*));
				tcp_ctask->r2t = r2t = NULL;
			}
		}

		if (r2t == NULL) {
			__kfifo_get(tcp_ctask->r2tqueue, (void*)&tcp_ctask->r2t,
				    sizeof(void*));
			r2t = tcp_ctask->r2t;
		}
		spin_unlock_bh(&session->lock);

		/* Waiting for more R2Ts to arrive. */
		if (r2t == NULL) {
			debug_tcp("no R2Ts yet\n");
			return 0;
		}

		debug_scsi("sol dout %p [dsn %d itt 0x%x doff %d dlen %d]\n",
			r2t, r2t->solicit_datasn - 1, ctask->itt,
			r2t->data_offset + r2t->sent, r2t->data_count);

		iscsi_tcp_send_hdr_prep(conn, &r2t->dtask.hdr,
					sizeof(struct iscsi_hdr));

		rc = iscsi_tcp_send_data_prep(conn, sdb->table.sgl,
					      sdb->table.nents,
					      r2t->data_offset + r2t->sent,
					      r2t->data_count);
		if (rc)
			goto fail;
		tcp_ctask->sent += r2t->data_count;
		r2t->sent += r2t->data_count;
		goto flush;
	}
	return 0;
fail:
	iscsi_conn_failure(conn, rc);
	return -EIO;
}

static struct iscsi_cls_conn *
iscsi_tcp_conn_create(struct iscsi_cls_session *cls_session, uint32_t conn_idx)
{
	struct iscsi_conn *conn;
	struct iscsi_cls_conn *cls_conn;
	struct iscsi_tcp_conn *tcp_conn;

	cls_conn = iscsi_conn_setup(cls_session, conn_idx);
	if (!cls_conn)
		return NULL;
	conn = cls_conn->dd_data;
	/*
	 * due to strange issues with iser these are not set
	 * in iscsi_conn_setup
	 */
	conn->max_recv_dlength = ISCSI_DEF_MAX_RECV_SEG_LEN;

	tcp_conn = kzalloc(sizeof(*tcp_conn), GFP_KERNEL);
	if (!tcp_conn)
		goto tcp_conn_alloc_fail;

	conn->dd_data = tcp_conn;
	tcp_conn->iscsi_conn = conn;

	tcp_conn->tx_hash.tfm = crypto_alloc_hash("crc32c", 0,
						  CRYPTO_ALG_ASYNC);
	tcp_conn->tx_hash.flags = 0;
	if (IS_ERR(tcp_conn->tx_hash.tfm))
		goto free_tcp_conn;

	tcp_conn->rx_hash.tfm = crypto_alloc_hash("crc32c", 0,
						  CRYPTO_ALG_ASYNC);
	tcp_conn->rx_hash.flags = 0;
	if (IS_ERR(tcp_conn->rx_hash.tfm))
		goto free_tx_tfm;

	return cls_conn;

free_tx_tfm:
	crypto_free_hash(tcp_conn->tx_hash.tfm);
free_tcp_conn:
	iscsi_conn_printk(KERN_ERR, conn,
			  "Could not create connection due to crc32c "
			  "loading error. Make sure the crc32c "
			  "module is built as a module or into the "
			  "kernel\n");
	kfree(tcp_conn);
tcp_conn_alloc_fail:
	iscsi_conn_teardown(cls_conn);
	return NULL;
}

static void
iscsi_tcp_release_conn(struct iscsi_conn *conn)
{
	struct iscsi_session *session = conn->session;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct socket *sock = tcp_conn->sock;

	if (!sock)
		return;

	sock_hold(sock->sk);
	iscsi_conn_restore_callbacks(tcp_conn);
	sock_put(sock->sk);

	spin_lock_bh(&session->lock);
	tcp_conn->sock = NULL;
	conn->recv_lock = NULL;
	spin_unlock_bh(&session->lock);
	sockfd_put(sock);
}

static void
iscsi_tcp_conn_destroy(struct iscsi_cls_conn *cls_conn)
{
	struct iscsi_conn *conn = cls_conn->dd_data;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;

	iscsi_tcp_release_conn(conn);
	iscsi_conn_teardown(cls_conn);

	if (tcp_conn->tx_hash.tfm)
		crypto_free_hash(tcp_conn->tx_hash.tfm);
	if (tcp_conn->rx_hash.tfm)
		crypto_free_hash(tcp_conn->rx_hash.tfm);

	kfree(tcp_conn);
}

static void
iscsi_tcp_conn_stop(struct iscsi_cls_conn *cls_conn, int flag)
{
	struct iscsi_conn *conn = cls_conn->dd_data;

	iscsi_conn_stop(cls_conn, flag);
	iscsi_tcp_release_conn(conn);
}

static int iscsi_tcp_get_addr(struct iscsi_conn *conn, struct socket *sock,
			      char *buf, int *port,
			      int (*getname)(struct socket *, struct sockaddr *,
					int *addrlen))
{
	struct sockaddr_storage *addr;
	struct sockaddr_in6 *sin6;
	struct sockaddr_in *sin;
	int rc = 0, len;

	addr = kmalloc(sizeof(*addr), GFP_KERNEL);
	if (!addr)
		return -ENOMEM;

	if (getname(sock, (struct sockaddr *) addr, &len)) {
		rc = -ENODEV;
		goto free_addr;
	}

	switch (addr->ss_family) {
	case AF_INET:
		sin = (struct sockaddr_in *)addr;
		spin_lock_bh(&conn->session->lock);
		sprintf(buf, NIPQUAD_FMT, NIPQUAD(sin->sin_addr.s_addr));
		*port = be16_to_cpu(sin->sin_port);
		spin_unlock_bh(&conn->session->lock);
		break;
	case AF_INET6:
		sin6 = (struct sockaddr_in6 *)addr;
		spin_lock_bh(&conn->session->lock);
		sprintf(buf, NIP6_FMT, NIP6(sin6->sin6_addr));
		*port = be16_to_cpu(sin6->sin6_port);
		spin_unlock_bh(&conn->session->lock);
		break;
	}
free_addr:
	kfree(addr);
	return rc;
}

static int
iscsi_tcp_conn_bind(struct iscsi_cls_session *cls_session,
		    struct iscsi_cls_conn *cls_conn, uint64_t transport_eph,
		    int is_leading)
{
	struct Scsi_Host *shost = iscsi_session_to_shost(cls_session);
	struct iscsi_host *ihost = shost_priv(shost);
	struct iscsi_conn *conn = cls_conn->dd_data;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	struct sock *sk;
	struct socket *sock;
	int err;

	/* lookup for existing socket */
	sock = sockfd_lookup((int)transport_eph, &err);
	if (!sock) {
		iscsi_conn_printk(KERN_ERR, conn,
				  "sockfd_lookup failed %d\n", err);
		return -EEXIST;
	}
	/*
	 * copy these values now because if we drop the session
	 * userspace may still want to query the values since we will
	 * be using them for the reconnect
	 */
	err = iscsi_tcp_get_addr(conn, sock, conn->portal_address,
				 &conn->portal_port, kernel_getpeername);
	if (err)
		goto free_socket;

	err = iscsi_tcp_get_addr(conn, sock, ihost->local_address,
				&ihost->local_port, kernel_getsockname);
	if (err)
		goto free_socket;

	err = iscsi_conn_bind(cls_session, cls_conn, is_leading);
	if (err)
		goto free_socket;

	/* bind iSCSI connection and socket */
	tcp_conn->sock = sock;

	/* setup Socket parameters */
	sk = sock->sk;
	sk->sk_reuse = 1;
	sk->sk_sndtimeo = 15 * HZ; /* FIXME: make it configurable */
	sk->sk_allocation = GFP_ATOMIC;

	/* FIXME: disable Nagle's algorithm */

	/*
	 * Intercept TCP callbacks for sendfile like receive
	 * processing.
	 */
	conn->recv_lock = &sk->sk_callback_lock;
	iscsi_conn_set_callbacks(conn);
	tcp_conn->sendpage = tcp_conn->sock->ops->sendpage;
	/*
	 * set receive state machine into initial state
	 */
	iscsi_tcp_hdr_recv_prep(tcp_conn);
	return 0;

free_socket:
	sockfd_put(sock);
	return err;
}

/* called with host lock */
static void
iscsi_tcp_mtask_init(struct iscsi_conn *conn, struct iscsi_mgmt_task *mtask)
{
	debug_scsi("mtask deq [cid %d itt 0x%x]\n", conn->id, mtask->itt);

	/* Prepare PDU, optionally w/ immediate data */
	iscsi_tcp_send_hdr_prep(conn, mtask->hdr, sizeof(*mtask->hdr));

	/* If we have immediate data, attach a payload */
	if (mtask->data_count)
		iscsi_tcp_send_linear_data_prepare(conn, mtask->data,
						   mtask->data_count);
}

static int
iscsi_r2tpool_alloc(struct iscsi_session *session)
{
	int i;
	int cmd_i;

	/*
	 * initialize per-task: R2T pool and xmit queue
	 */
	for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
	        struct iscsi_cmd_task *ctask = session->cmds[cmd_i];
		struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;

		/*
		 * pre-allocated x4 as much r2ts to handle race when
		 * target acks DataOut faster than we data_xmit() queues
		 * could replenish r2tqueue.
		 */

		/* R2T pool */
		if (iscsi_pool_init(&tcp_ctask->r2tpool, session->max_r2t * 4, NULL,
				    sizeof(struct iscsi_r2t_info))) {
			goto r2t_alloc_fail;
		}

		/* R2T xmit queue */
		tcp_ctask->r2tqueue = kfifo_alloc(
		      session->max_r2t * 4 * sizeof(void*), GFP_KERNEL, NULL);
		if (tcp_ctask->r2tqueue == ERR_PTR(-ENOMEM)) {
			iscsi_pool_free(&tcp_ctask->r2tpool);
			goto r2t_alloc_fail;
		}
	}

	return 0;

r2t_alloc_fail:
	for (i = 0; i < cmd_i; i++) {
		struct iscsi_cmd_task *ctask = session->cmds[i];
		struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;

		kfifo_free(tcp_ctask->r2tqueue);
		iscsi_pool_free(&tcp_ctask->r2tpool);
	}
	return -ENOMEM;
}

static void
iscsi_r2tpool_free(struct iscsi_session *session)
{
	int i;

	for (i = 0; i < session->cmds_max; i++) {
		struct iscsi_cmd_task *ctask = session->cmds[i];
		struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;

		kfifo_free(tcp_ctask->r2tqueue);
		iscsi_pool_free(&tcp_ctask->r2tpool);
	}
}

static int
iscsi_conn_set_param(struct iscsi_cls_conn *cls_conn, enum iscsi_param param,
		     char *buf, int buflen)
{
	struct iscsi_conn *conn = cls_conn->dd_data;
	struct iscsi_session *session = conn->session;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
	int value;

	switch(param) {
	case ISCSI_PARAM_HDRDGST_EN:
		iscsi_set_param(cls_conn, param, buf, buflen);
		break;
	case ISCSI_PARAM_DATADGST_EN:
		iscsi_set_param(cls_conn, param, buf, buflen);
		tcp_conn->sendpage = conn->datadgst_en ?
			sock_no_sendpage : tcp_conn->sock->ops->sendpage;
		break;
	case ISCSI_PARAM_MAX_R2T:
		sscanf(buf, "%d", &value);
		if (value <= 0 || !is_power_of_2(value))
			return -EINVAL;
		if (session->max_r2t == value)
			break;
		iscsi_r2tpool_free(session);
		iscsi_set_param(cls_conn, param, buf, buflen);
		if (iscsi_r2tpool_alloc(session))
			return -ENOMEM;
		break;
	default:
		return iscsi_set_param(cls_conn, param, buf, buflen);
	}

	return 0;
}

static int
iscsi_tcp_conn_get_param(struct iscsi_cls_conn *cls_conn,
			 enum iscsi_param param, char *buf)
{
	struct iscsi_conn *conn = cls_conn->dd_data;
	int len;

	switch(param) {
	case ISCSI_PARAM_CONN_PORT:
		spin_lock_bh(&conn->session->lock);
		len = sprintf(buf, "%hu\n", conn->portal_port);
		spin_unlock_bh(&conn->session->lock);
		break;
	case ISCSI_PARAM_CONN_ADDRESS:
		spin_lock_bh(&conn->session->lock);
		len = sprintf(buf, "%s\n", conn->portal_address);
		spin_unlock_bh(&conn->session->lock);
		break;
	default:
		return iscsi_conn_get_param(cls_conn, param, buf);
	}

	return len;
}

static void
iscsi_conn_get_stats(struct iscsi_cls_conn *cls_conn, struct iscsi_stats *stats)
{
	struct iscsi_conn *conn = cls_conn->dd_data;
	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;

	stats->txdata_octets = conn->txdata_octets;
	stats->rxdata_octets = conn->rxdata_octets;
	stats->scsicmd_pdus = conn->scsicmd_pdus_cnt;
	stats->dataout_pdus = conn->dataout_pdus_cnt;
	stats->scsirsp_pdus = conn->scsirsp_pdus_cnt;
	stats->datain_pdus = conn->datain_pdus_cnt;
	stats->r2t_pdus = conn->r2t_pdus_cnt;
	stats->tmfcmd_pdus = conn->tmfcmd_pdus_cnt;
	stats->tmfrsp_pdus = conn->tmfrsp_pdus_cnt;
	stats->custom_length = 3;
	strcpy(stats->custom[0].desc, "tx_sendpage_failures");
	stats->custom[0].value = tcp_conn->sendpage_failures_cnt;
	strcpy(stats->custom[1].desc, "rx_discontiguous_hdr");
	stats->custom[1].value = tcp_conn->discontiguous_hdr_cnt;
	strcpy(stats->custom[2].desc, "eh_abort_cnt");
	stats->custom[2].value = conn->eh_abort_cnt;
}

static struct iscsi_cls_session *
iscsi_tcp_session_create(struct Scsi_Host *shost, uint16_t cmds_max,
			 uint16_t qdepth, uint32_t initial_cmdsn,
			 uint32_t *hostno)
{
	struct iscsi_cls_session *cls_session;
	struct iscsi_session *session;
	int cmd_i;

	if (shost) {
		printk(KERN_ERR "iscsi_tcp: invalid shost %d.\n",
		       shost->host_no);
		return NULL;
	}

	shost = scsi_host_alloc(&iscsi_sht, sizeof(struct iscsi_host));
	if (!shost)
		return NULL;
	shost->transportt = iscsi_tcp_scsi_transport;
	shost->max_lun = iscsi_max_lun;
	shost->max_id = 0;
	shost->max_channel = 0;
	shost->max_cmd_len = 16;

	iscsi_host_setup(shost, qdepth);

	if (scsi_add_host(shost, NULL))
		goto free_host;
	*hostno = shost->host_no;

	cls_session = iscsi_session_setup(&iscsi_tcp_transport, shost, cmds_max,
					  sizeof(struct iscsi_tcp_cmd_task),
					  sizeof(struct iscsi_tcp_mgmt_task),
					  initial_cmdsn);
	if (!cls_session)
		goto remove_host;
	session = cls_session->dd_data;

	shost->can_queue = session->cmds_max;
	for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
		struct iscsi_cmd_task *ctask = session->cmds[cmd_i];
		struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;

		ctask->hdr = &tcp_ctask->hdr.cmd_hdr;
		ctask->hdr_max = sizeof(tcp_ctask->hdr) - ISCSI_DIGEST_SIZE;
	}

	for (cmd_i = 0; cmd_i < session->mgmtpool_max; cmd_i++) {
		struct iscsi_mgmt_task *mtask = session->mgmt_cmds[cmd_i];
		struct iscsi_tcp_mgmt_task *tcp_mtask = mtask->dd_data;

		mtask->hdr = (struct iscsi_hdr *) &tcp_mtask->hdr;
	}

	if (iscsi_r2tpool_alloc(session))
		goto remove_session;
	return cls_session;

remove_session:
	iscsi_session_teardown(cls_session);
remove_host:
	scsi_remove_host(shost);
free_host:
	iscsi_host_teardown(shost);
	scsi_host_put(shost);
	return NULL;
}

static void iscsi_tcp_session_destroy(struct iscsi_cls_session *cls_session)
{
	struct Scsi_Host *shost = iscsi_session_to_shost(cls_session);

	iscsi_r2tpool_free(cls_session->dd_data);
	iscsi_session_teardown(cls_session);

	scsi_remove_host(shost);
	iscsi_host_teardown(shost);
	scsi_host_put(shost);
}

static int iscsi_tcp_slave_configure(struct scsi_device *sdev)
{
	blk_queue_bounce_limit(sdev->request_queue, BLK_BOUNCE_ANY);
	blk_queue_dma_alignment(sdev->request_queue, 0);
	return 0;
}

static struct scsi_host_template iscsi_sht = {
	.module			= THIS_MODULE,
	.name			= "iSCSI Initiator over TCP/IP",
	.queuecommand           = iscsi_queuecommand,
	.change_queue_depth	= iscsi_change_queue_depth,
	.can_queue		= ISCSI_DEF_XMIT_CMDS_MAX - 1,
	.sg_tablesize		= 4096,
	.max_sectors		= 0xFFFF,
	.cmd_per_lun		= ISCSI_DEF_CMD_PER_LUN,
	.eh_abort_handler       = iscsi_eh_abort,
	.eh_device_reset_handler= iscsi_eh_device_reset,
	.eh_host_reset_handler	= iscsi_eh_host_reset,
	.use_clustering         = DISABLE_CLUSTERING,
	.slave_configure        = iscsi_tcp_slave_configure,
	.proc_name		= "iscsi_tcp",
	.this_id		= -1,
};

static struct iscsi_transport iscsi_tcp_transport = {
	.owner			= THIS_MODULE,
	.name			= "tcp",
	.caps			= CAP_RECOVERY_L0 | CAP_MULTI_R2T | CAP_HDRDGST
				  | CAP_DATADGST,
	.param_mask		= ISCSI_MAX_RECV_DLENGTH |
				  ISCSI_MAX_XMIT_DLENGTH |
				  ISCSI_HDRDGST_EN |
				  ISCSI_DATADGST_EN |
				  ISCSI_INITIAL_R2T_EN |
				  ISCSI_MAX_R2T |
				  ISCSI_IMM_DATA_EN |
				  ISCSI_FIRST_BURST |
				  ISCSI_MAX_BURST |
				  ISCSI_PDU_INORDER_EN |
				  ISCSI_DATASEQ_INORDER_EN |
				  ISCSI_ERL |
				  ISCSI_CONN_PORT |
				  ISCSI_CONN_ADDRESS |
				  ISCSI_EXP_STATSN |
				  ISCSI_PERSISTENT_PORT |
				  ISCSI_PERSISTENT_ADDRESS |
				  ISCSI_TARGET_NAME | ISCSI_TPGT |
				  ISCSI_USERNAME | ISCSI_PASSWORD |
				  ISCSI_USERNAME_IN | ISCSI_PASSWORD_IN |
				  ISCSI_FAST_ABORT | ISCSI_ABORT_TMO |
				  ISCSI_LU_RESET_TMO |
				  ISCSI_PING_TMO | ISCSI_RECV_TMO,
	.host_param_mask	= ISCSI_HOST_HWADDRESS | ISCSI_HOST_IPADDRESS |
				  ISCSI_HOST_INITIATOR_NAME |
				  ISCSI_HOST_NETDEV_NAME,
	.conndata_size		= sizeof(struct iscsi_conn),
	.sessiondata_size	= sizeof(struct iscsi_session),
	/* session management */
	.create_session		= iscsi_tcp_session_create,
	.destroy_session	= iscsi_tcp_session_destroy,
	/* connection management */
	.create_conn		= iscsi_tcp_conn_create,
	.bind_conn		= iscsi_tcp_conn_bind,
	.destroy_conn		= iscsi_tcp_conn_destroy,
	.set_param		= iscsi_conn_set_param,
	.get_conn_param		= iscsi_tcp_conn_get_param,
	.get_session_param	= iscsi_session_get_param,
	.start_conn		= iscsi_conn_start,
	.stop_conn		= iscsi_tcp_conn_stop,
	/* iscsi host params */
	.get_host_param		= iscsi_host_get_param,
	.set_host_param		= iscsi_host_set_param,
	/* IO */
	.send_pdu		= iscsi_conn_send_pdu,
	.get_stats		= iscsi_conn_get_stats,
	.init_cmd_task		= iscsi_tcp_ctask_init,
	.init_mgmt_task		= iscsi_tcp_mtask_init,
	.xmit_cmd_task		= iscsi_tcp_ctask_xmit,
	.xmit_mgmt_task		= iscsi_tcp_mtask_xmit,
	.cleanup_cmd_task	= iscsi_tcp_cleanup_ctask,
	/* recovery */
	.session_recovery_timedout = iscsi_session_recovery_timedout,
};

static int __init
iscsi_tcp_init(void)
{
	if (iscsi_max_lun < 1) {
		printk(KERN_ERR "iscsi_tcp: Invalid max_lun value of %u\n",
		       iscsi_max_lun);
		return -EINVAL;
	}

	iscsi_tcp_scsi_transport = iscsi_register_transport(
							&iscsi_tcp_transport);
	if (!iscsi_tcp_scsi_transport)
		return -ENODEV;

	return 0;
}

static void __exit
iscsi_tcp_exit(void)
{
	iscsi_unregister_transport(&iscsi_tcp_transport);
}

module_init(iscsi_tcp_init);
module_exit(iscsi_tcp_exit);