summaryrefslogtreecommitdiffstats
path: root/kernel/drivers/target/iscsi/iscsi_target_tmr.c
blob: 11320df939f7f19d5406fc857bc5e69b160f9593 (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
/*******************************************************************************
 * This file contains the iSCSI Target specific Task Management functions.
 *
 * (c) Copyright 2007-2013 Datera, Inc.
 *
 * Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
 *
 * 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.
 ******************************************************************************/

#include <asm/unaligned.h>
#include <scsi/scsi_proto.h>
#include <scsi/iscsi_proto.h>
#include <target/target_core_base.h>
#include <target/target_core_fabric.h>
#include <target/iscsi/iscsi_transport.h>

#include <target/iscsi/iscsi_target_core.h>
#include "iscsi_target_seq_pdu_list.h"
#include "iscsi_target_datain_values.h"
#include "iscsi_target_device.h"
#include "iscsi_target_erl0.h"
#include "iscsi_target_erl1.h"
#include "iscsi_target_erl2.h"
#include "iscsi_target_tmr.h"
#include "iscsi_target_tpg.h"
#include "iscsi_target_util.h"
#include "iscsi_target.h"

u8 iscsit_tmr_abort_task(
	struct iscsi_cmd *cmd,
	unsigned char *buf)
{
	struct iscsi_cmd *ref_cmd;
	struct iscsi_conn *conn = cmd->conn;
	struct iscsi_tmr_req *tmr_req = cmd->tmr_req;
	struct se_tmr_req *se_tmr = cmd->se_cmd.se_tmr_req;
	struct iscsi_tm *hdr = (struct iscsi_tm *) buf;

	ref_cmd = iscsit_find_cmd_from_itt(conn, hdr->rtt);
	if (!ref_cmd) {
		pr_err("Unable to locate RefTaskTag: 0x%08x on CID:"
			" %hu.\n", hdr->rtt, conn->cid);
		return (iscsi_sna_gte(be32_to_cpu(hdr->refcmdsn), conn->sess->exp_cmd_sn) &&
			iscsi_sna_lte(be32_to_cpu(hdr->refcmdsn), (u32) atomic_read(&conn->sess->max_cmd_sn))) ?
			ISCSI_TMF_RSP_COMPLETE : ISCSI_TMF_RSP_NO_TASK;
	}
	if (ref_cmd->cmd_sn != be32_to_cpu(hdr->refcmdsn)) {
		pr_err("RefCmdSN 0x%08x does not equal"
			" task's CmdSN 0x%08x. Rejecting ABORT_TASK.\n",
			hdr->refcmdsn, ref_cmd->cmd_sn);
		return ISCSI_TMF_RSP_REJECTED;
	}

	se_tmr->ref_task_tag		= (__force u32)hdr->rtt;
	tmr_req->ref_cmd		= ref_cmd;
	tmr_req->exp_data_sn		= be32_to_cpu(hdr->exp_datasn);

	return ISCSI_TMF_RSP_COMPLETE;
}

/*
 *	Called from iscsit_handle_task_mgt_cmd().
 */
int iscsit_tmr_task_warm_reset(
	struct iscsi_conn *conn,
	struct iscsi_tmr_req *tmr_req,
	unsigned char *buf)
{
	struct iscsi_session *sess = conn->sess;
	struct iscsi_node_attrib *na = iscsit_tpg_get_node_attrib(sess);

	if (!na->tmr_warm_reset) {
		pr_err("TMR Opcode TARGET_WARM_RESET authorization"
			" failed for Initiator Node: %s\n",
			sess->se_sess->se_node_acl->initiatorname);
		 return -1;
	}
	/*
	 * Do the real work in transport_generic_do_tmr().
	 */
	return 0;
}

int iscsit_tmr_task_cold_reset(
	struct iscsi_conn *conn,
	struct iscsi_tmr_req *tmr_req,
	unsigned char *buf)
{
	struct iscsi_session *sess = conn->sess;
	struct iscsi_node_attrib *na = iscsit_tpg_get_node_attrib(sess);

	if (!na->tmr_cold_reset) {
		pr_err("TMR Opcode TARGET_COLD_RESET authorization"
			" failed for Initiator Node: %s\n",
			sess->se_sess->se_node_acl->initiatorname);
		return -1;
	}
	/*
	 * Do the real work in transport_generic_do_tmr().
	 */
	return 0;
}

u8 iscsit_tmr_task_reassign(
	struct iscsi_cmd *cmd,
	unsigned char *buf)
{
	struct iscsi_cmd *ref_cmd = NULL;
	struct iscsi_conn *conn = cmd->conn;
	struct iscsi_conn_recovery *cr = NULL;
	struct iscsi_tmr_req *tmr_req = cmd->tmr_req;
	struct se_tmr_req *se_tmr = cmd->se_cmd.se_tmr_req;
	struct iscsi_tm *hdr = (struct iscsi_tm *) buf;
	u64 ret, ref_lun;

	pr_debug("Got TASK_REASSIGN TMR ITT: 0x%08x,"
		" RefTaskTag: 0x%08x, ExpDataSN: 0x%08x, CID: %hu\n",
		hdr->itt, hdr->rtt, hdr->exp_datasn, conn->cid);

	if (conn->sess->sess_ops->ErrorRecoveryLevel != 2) {
		pr_err("TMR TASK_REASSIGN not supported in ERL<2,"
				" ignoring request.\n");
		return ISCSI_TMF_RSP_NOT_SUPPORTED;
	}

	ret = iscsit_find_cmd_for_recovery(conn->sess, &ref_cmd, &cr, hdr->rtt);
	if (ret == -2) {
		pr_err("Command ITT: 0x%08x is still alligent to CID:"
			" %hu\n", ref_cmd->init_task_tag, cr->cid);
		return ISCSI_TMF_RSP_TASK_ALLEGIANT;
	} else if (ret == -1) {
		pr_err("Unable to locate RefTaskTag: 0x%08x in"
			" connection recovery command list.\n", hdr->rtt);
		return ISCSI_TMF_RSP_NO_TASK;
	}
	/*
	 * Temporary check to prevent connection recovery for
	 * connections with a differing Max*DataSegmentLength.
	 */
	if (cr->maxrecvdatasegmentlength !=
	    conn->conn_ops->MaxRecvDataSegmentLength) {
		pr_err("Unable to perform connection recovery for"
			" differing MaxRecvDataSegmentLength, rejecting"
			" TMR TASK_REASSIGN.\n");
		return ISCSI_TMF_RSP_REJECTED;
	}
	if (cr->maxxmitdatasegmentlength !=
	    conn->conn_ops->MaxXmitDataSegmentLength) {
		pr_err("Unable to perform connection recovery for"
			" differing MaxXmitDataSegmentLength, rejecting"
			" TMR TASK_REASSIGN.\n");
		return ISCSI_TMF_RSP_REJECTED;
	}

	ref_lun = scsilun_to_int(&hdr->lun);
	if (ref_lun != ref_cmd->se_cmd.orig_fe_lun) {
		pr_err("Unable to perform connection recovery for"
			" differing ref_lun: %llu ref_cmd orig_fe_lun: %llu\n",
			ref_lun, ref_cmd->se_cmd.orig_fe_lun);
		return ISCSI_TMF_RSP_REJECTED;
	}

	se_tmr->ref_task_tag		= (__force u32)hdr->rtt;
	tmr_req->ref_cmd		= ref_cmd;
	tmr_req->exp_data_sn		= be32_to_cpu(hdr->exp_datasn);
	tmr_req->conn_recovery		= cr;
	tmr_req->task_reassign		= 1;
	/*
	 * Command can now be reassigned to a new connection.
	 * The task management response must be sent before the
	 * reassignment actually happens.  See iscsi_tmr_post_handler().
	 */
	return ISCSI_TMF_RSP_COMPLETE;
}

static void iscsit_task_reassign_remove_cmd(
	struct iscsi_cmd *cmd,
	struct iscsi_conn_recovery *cr,
	struct iscsi_session *sess)
{
	int ret;

	spin_lock(&cr->conn_recovery_cmd_lock);
	ret = iscsit_remove_cmd_from_connection_recovery(cmd, sess);
	spin_unlock(&cr->conn_recovery_cmd_lock);
	if (!ret) {
		pr_debug("iSCSI connection recovery successful for CID:"
			" %hu on SID: %u\n", cr->cid, sess->sid);
		iscsit_remove_active_connection_recovery_entry(cr, sess);
	}
}

static int iscsit_task_reassign_complete_nop_out(
	struct iscsi_tmr_req *tmr_req,
	struct iscsi_conn *conn)
{
	struct iscsi_cmd *cmd = tmr_req->ref_cmd;
	struct iscsi_conn_recovery *cr;

	if (!cmd->cr) {
		pr_err("struct iscsi_conn_recovery pointer for ITT: 0x%08x"
			" is NULL!\n", cmd->init_task_tag);
		return -1;
	}
	cr = cmd->cr;

	/*
	 * Reset the StatSN so a new one for this commands new connection
	 * will be assigned.
	 * Reset the ExpStatSN as well so we may receive Status SNACKs.
	 */
	cmd->stat_sn = cmd->exp_stat_sn = 0;

	iscsit_task_reassign_remove_cmd(cmd, cr, conn->sess);

	spin_lock_bh(&conn->cmd_lock);
	list_add_tail(&cmd->i_conn_node, &conn->conn_cmd_list);
	spin_unlock_bh(&conn->cmd_lock);

	cmd->i_state = ISTATE_SEND_NOPIN;
	iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
	return 0;
}

static int iscsit_task_reassign_complete_write(
	struct iscsi_cmd *cmd,
	struct iscsi_tmr_req *tmr_req)
{
	int no_build_r2ts = 0;
	u32 length = 0, offset = 0;
	struct iscsi_conn *conn = cmd->conn;
	struct se_cmd *se_cmd = &cmd->se_cmd;
	/*
	 * The Initiator must not send a R2T SNACK with a Begrun less than
	 * the TMR TASK_REASSIGN's ExpDataSN.
	 */
	if (!tmr_req->exp_data_sn) {
		cmd->cmd_flags &= ~ICF_GOT_DATACK_SNACK;
		cmd->acked_data_sn = 0;
	} else {
		cmd->cmd_flags |= ICF_GOT_DATACK_SNACK;
		cmd->acked_data_sn = (tmr_req->exp_data_sn - 1);
	}

	/*
	 * The TMR TASK_REASSIGN's ExpDataSN contains the next R2TSN the
	 * Initiator is expecting.  The Target controls all WRITE operations
	 * so if we have received all DataOUT we can safety ignore Initiator.
	 */
	if (cmd->cmd_flags & ICF_GOT_LAST_DATAOUT) {
		if (!(cmd->se_cmd.transport_state & CMD_T_SENT)) {
			pr_debug("WRITE ITT: 0x%08x: t_state: %d"
				" never sent to transport\n",
				cmd->init_task_tag, cmd->se_cmd.t_state);
			target_execute_cmd(se_cmd);
			return 0;
		}

		cmd->i_state = ISTATE_SEND_STATUS;
		iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
		return 0;
	}

	/*
	 * Special case to deal with DataSequenceInOrder=No and Non-Immeidate
	 * Unsolicited DataOut.
	 */
	if (cmd->unsolicited_data) {
		cmd->unsolicited_data = 0;

		offset = cmd->next_burst_len = cmd->write_data_done;

		if ((conn->sess->sess_ops->FirstBurstLength - offset) >=
		     cmd->se_cmd.data_length) {
			no_build_r2ts = 1;
			length = (cmd->se_cmd.data_length - offset);
		} else
			length = (conn->sess->sess_ops->FirstBurstLength - offset);

		spin_lock_bh(&cmd->r2t_lock);
		if (iscsit_add_r2t_to_list(cmd, offset, length, 0, 0) < 0) {
			spin_unlock_bh(&cmd->r2t_lock);
			return -1;
		}
		cmd->outstanding_r2ts++;
		spin_unlock_bh(&cmd->r2t_lock);

		if (no_build_r2ts)
			return 0;
	}
	/*
	 * iscsit_build_r2ts_for_cmd() can handle the rest from here.
	 */
	return conn->conn_transport->iscsit_get_dataout(conn, cmd, true);
}

static int iscsit_task_reassign_complete_read(
	struct iscsi_cmd *cmd,
	struct iscsi_tmr_req *tmr_req)
{
	struct iscsi_conn *conn = cmd->conn;
	struct iscsi_datain_req *dr;
	struct se_cmd *se_cmd = &cmd->se_cmd;
	/*
	 * The Initiator must not send a Data SNACK with a BegRun less than
	 * the TMR TASK_REASSIGN's ExpDataSN.
	 */
	if (!tmr_req->exp_data_sn) {
		cmd->cmd_flags &= ~ICF_GOT_DATACK_SNACK;
		cmd->acked_data_sn = 0;
	} else {
		cmd->cmd_flags |= ICF_GOT_DATACK_SNACK;
		cmd->acked_data_sn = (tmr_req->exp_data_sn - 1);
	}

	if (!(cmd->se_cmd.transport_state & CMD_T_SENT)) {
		pr_debug("READ ITT: 0x%08x: t_state: %d never sent to"
			" transport\n", cmd->init_task_tag,
			cmd->se_cmd.t_state);
		transport_handle_cdb_direct(se_cmd);
		return 0;
	}

	if (!(se_cmd->transport_state & CMD_T_COMPLETE)) {
		pr_err("READ ITT: 0x%08x: t_state: %d, never returned"
			" from transport\n", cmd->init_task_tag,
			cmd->se_cmd.t_state);
		return -1;
	}

	dr = iscsit_allocate_datain_req();
	if (!dr)
		return -1;
	/*
	 * The TMR TASK_REASSIGN's ExpDataSN contains the next DataSN the
	 * Initiator is expecting.
	 */
	dr->data_sn = dr->begrun = tmr_req->exp_data_sn;
	dr->runlength = 0;
	dr->generate_recovery_values = 1;
	dr->recovery = DATAIN_CONNECTION_RECOVERY;

	iscsit_attach_datain_req(cmd, dr);

	cmd->i_state = ISTATE_SEND_DATAIN;
	iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
	return 0;
}

static int iscsit_task_reassign_complete_none(
	struct iscsi_cmd *cmd,
	struct iscsi_tmr_req *tmr_req)
{
	struct iscsi_conn *conn = cmd->conn;

	cmd->i_state = ISTATE_SEND_STATUS;
	iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
	return 0;
}

static int iscsit_task_reassign_complete_scsi_cmnd(
	struct iscsi_tmr_req *tmr_req,
	struct iscsi_conn *conn)
{
	struct iscsi_cmd *cmd = tmr_req->ref_cmd;
	struct iscsi_conn_recovery *cr;

	if (!cmd->cr) {
		pr_err("struct iscsi_conn_recovery pointer for ITT: 0x%08x"
			" is NULL!\n", cmd->init_task_tag);
		return -1;
	}
	cr = cmd->cr;

	/*
	 * Reset the StatSN so a new one for this commands new connection
	 * will be assigned.
	 * Reset the ExpStatSN as well so we may receive Status SNACKs.
	 */
	cmd->stat_sn = cmd->exp_stat_sn = 0;

	iscsit_task_reassign_remove_cmd(cmd, cr, conn->sess);

	spin_lock_bh(&conn->cmd_lock);
	list_add_tail(&cmd->i_conn_node, &conn->conn_cmd_list);
	spin_unlock_bh(&conn->cmd_lock);

	if (cmd->se_cmd.se_cmd_flags & SCF_SENT_CHECK_CONDITION) {
		cmd->i_state = ISTATE_SEND_STATUS;
		iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
		return 0;
	}

	switch (cmd->data_direction) {
	case DMA_TO_DEVICE:
		return iscsit_task_reassign_complete_write(cmd, tmr_req);
	case DMA_FROM_DEVICE:
		return iscsit_task_reassign_complete_read(cmd, tmr_req);
	case DMA_NONE:
		return iscsit_task_reassign_complete_none(cmd, tmr_req);
	default:
		pr_err("Unknown cmd->data_direction: 0x%02x\n",
				cmd->data_direction);
		return -1;
	}

	return 0;
}

static int iscsit_task_reassign_complete(
	struct iscsi_tmr_req *tmr_req,
	struct iscsi_conn *conn)
{
	struct iscsi_cmd *cmd;
	int ret = 0;

	if (!tmr_req->ref_cmd) {
		pr_err("TMR Request is missing a RefCmd struct iscsi_cmd.\n");
		return -1;
	}
	cmd = tmr_req->ref_cmd;

	cmd->conn = conn;

	switch (cmd->iscsi_opcode) {
	case ISCSI_OP_NOOP_OUT:
		ret = iscsit_task_reassign_complete_nop_out(tmr_req, conn);
		break;
	case ISCSI_OP_SCSI_CMD:
		ret = iscsit_task_reassign_complete_scsi_cmnd(tmr_req, conn);
		break;
	default:
		 pr_err("Illegal iSCSI Opcode 0x%02x during"
			" command realligence\n", cmd->iscsi_opcode);
		return -1;
	}

	if (ret != 0)
		return ret;

	pr_debug("Completed connection realligence for Opcode: 0x%02x,"
		" ITT: 0x%08x to CID: %hu.\n", cmd->iscsi_opcode,
			cmd->init_task_tag, conn->cid);

	return 0;
}

/*
 *	Handles special after-the-fact actions related to TMRs.
 *	Right now the only one that its really needed for is
 *	connection recovery releated TASK_REASSIGN.
 */
int iscsit_tmr_post_handler(struct iscsi_cmd *cmd, struct iscsi_conn *conn)
{
	struct iscsi_tmr_req *tmr_req = cmd->tmr_req;
	struct se_tmr_req *se_tmr = cmd->se_cmd.se_tmr_req;

	if (tmr_req->task_reassign &&
	   (se_tmr->response == ISCSI_TMF_RSP_COMPLETE))
		return iscsit_task_reassign_complete(tmr_req, conn);

	return 0;
}
EXPORT_SYMBOL(iscsit_tmr_post_handler);

/*
 *	Nothing to do here, but leave it for good measure. :-)
 */
static int iscsit_task_reassign_prepare_read(
	struct iscsi_tmr_req *tmr_req,
	struct iscsi_conn *conn)
{
	return 0;
}

static void iscsit_task_reassign_prepare_unsolicited_dataout(
	struct iscsi_cmd *cmd,
	struct iscsi_conn *conn)
{
	int i, j;
	struct iscsi_pdu *pdu = NULL;
	struct iscsi_seq *seq = NULL;

	if (conn->sess->sess_ops->DataSequenceInOrder) {
		cmd->data_sn = 0;

		if (cmd->immediate_data)
			cmd->r2t_offset += (cmd->first_burst_len -
				cmd->seq_start_offset);

		if (conn->sess->sess_ops->DataPDUInOrder) {
			cmd->write_data_done -= (cmd->immediate_data) ?
						(cmd->first_burst_len -
						 cmd->seq_start_offset) :
						 cmd->first_burst_len;
			cmd->first_burst_len = 0;
			return;
		}

		for (i = 0; i < cmd->pdu_count; i++) {
			pdu = &cmd->pdu_list[i];

			if (pdu->status != ISCSI_PDU_RECEIVED_OK)
				continue;

			if ((pdu->offset >= cmd->seq_start_offset) &&
			   ((pdu->offset + pdu->length) <=
			     cmd->seq_end_offset)) {
				cmd->first_burst_len -= pdu->length;
				cmd->write_data_done -= pdu->length;
				pdu->status = ISCSI_PDU_NOT_RECEIVED;
			}
		}
	} else {
		for (i = 0; i < cmd->seq_count; i++) {
			seq = &cmd->seq_list[i];

			if (seq->type != SEQTYPE_UNSOLICITED)
				continue;

			cmd->write_data_done -=
					(seq->offset - seq->orig_offset);
			cmd->first_burst_len = 0;
			seq->data_sn = 0;
			seq->offset = seq->orig_offset;
			seq->next_burst_len = 0;
			seq->status = DATAOUT_SEQUENCE_WITHIN_COMMAND_RECOVERY;

			if (conn->sess->sess_ops->DataPDUInOrder)
				continue;

			for (j = 0; j < seq->pdu_count; j++) {
				pdu = &cmd->pdu_list[j+seq->pdu_start];

				if (pdu->status != ISCSI_PDU_RECEIVED_OK)
					continue;

				pdu->status = ISCSI_PDU_NOT_RECEIVED;
			}
		}
	}
}

static int iscsit_task_reassign_prepare_write(
	struct iscsi_tmr_req *tmr_req,
	struct iscsi_conn *conn)
{
	struct iscsi_cmd *cmd = tmr_req->ref_cmd;
	struct iscsi_pdu *pdu = NULL;
	struct iscsi_r2t *r2t = NULL, *r2t_tmp;
	int first_incomplete_r2t = 1, i = 0;

	/*
	 * The command was in the process of receiving Unsolicited DataOUT when
	 * the connection failed.
	 */
	if (cmd->unsolicited_data)
		iscsit_task_reassign_prepare_unsolicited_dataout(cmd, conn);

	/*
	 * The Initiator is requesting R2Ts starting from zero,  skip
	 * checking acknowledged R2Ts and start checking struct iscsi_r2ts
	 * greater than zero.
	 */
	if (!tmr_req->exp_data_sn)
		goto drop_unacknowledged_r2ts;

	/*
	 * We now check that the PDUs in DataOUT sequences below
	 * the TMR TASK_REASSIGN ExpDataSN (R2TSN the Initiator is
	 * expecting next) have all the DataOUT they require to complete
	 * the DataOUT sequence.  First scan from R2TSN 0 to TMR
	 * TASK_REASSIGN ExpDataSN-1.
	 *
	 * If we have not received all DataOUT in question,  we must
	 * make sure to make the appropriate changes to values in
	 * struct iscsi_cmd (and elsewhere depending on session parameters)
	 * so iscsit_build_r2ts_for_cmd() in iscsit_task_reassign_complete_write()
	 * will resend a new R2T for the DataOUT sequences in question.
	 */
	spin_lock_bh(&cmd->r2t_lock);
	if (list_empty(&cmd->cmd_r2t_list)) {
		spin_unlock_bh(&cmd->r2t_lock);
		return -1;
	}

	list_for_each_entry(r2t, &cmd->cmd_r2t_list, r2t_list) {

		if (r2t->r2t_sn >= tmr_req->exp_data_sn)
			continue;
		/*
		 * Safely ignore Recovery R2Ts and R2Ts that have completed
		 * DataOUT sequences.
		 */
		if (r2t->seq_complete)
			continue;

		if (r2t->recovery_r2t)
			continue;

		/*
		 *                 DataSequenceInOrder=Yes:
		 *
		 * Taking into account the iSCSI implementation requirement of
		 * MaxOutstandingR2T=1 while ErrorRecoveryLevel>0 and
		 * DataSequenceInOrder=Yes, we must take into consideration
		 * the following:
		 *
		 *                  DataSequenceInOrder=No:
		 *
		 * Taking into account that the Initiator controls the (possibly
		 * random) PDU Order in (possibly random) Sequence Order of
		 * DataOUT the target requests with R2Ts,  we must take into
		 * consideration the following:
		 *
		 *      DataPDUInOrder=Yes for DataSequenceInOrder=[Yes,No]:
		 *
		 * While processing non-complete R2T DataOUT sequence requests
		 * the Target will re-request only the total sequence length
		 * minus current received offset.  This is because we must
		 * assume the initiator will continue sending DataOUT from the
		 * last PDU before the connection failed.
		 *
		 *      DataPDUInOrder=No for DataSequenceInOrder=[Yes,No]:
		 *
		 * While processing non-complete R2T DataOUT sequence requests
		 * the Target will re-request the entire DataOUT sequence if
		 * any single PDU is missing from the sequence.  This is because
		 * we have no logical method to determine the next PDU offset,
		 * and we must assume the Initiator will be sending any random
		 * PDU offset in the current sequence after TASK_REASSIGN
		 * has completed.
		 */
		if (conn->sess->sess_ops->DataSequenceInOrder) {
			if (!first_incomplete_r2t) {
				cmd->r2t_offset -= r2t->xfer_len;
				goto next;
			}

			if (conn->sess->sess_ops->DataPDUInOrder) {
				cmd->data_sn = 0;
				cmd->r2t_offset -= (r2t->xfer_len -
					cmd->next_burst_len);
				first_incomplete_r2t = 0;
				goto next;
			}

			cmd->data_sn = 0;
			cmd->r2t_offset -= r2t->xfer_len;

			for (i = 0; i < cmd->pdu_count; i++) {
				pdu = &cmd->pdu_list[i];

				if (pdu->status != ISCSI_PDU_RECEIVED_OK)
					continue;

				if ((pdu->offset >= r2t->offset) &&
				    (pdu->offset < (r2t->offset +
						r2t->xfer_len))) {
					cmd->next_burst_len -= pdu->length;
					cmd->write_data_done -= pdu->length;
					pdu->status = ISCSI_PDU_NOT_RECEIVED;
				}
			}

			first_incomplete_r2t = 0;
		} else {
			struct iscsi_seq *seq;

			seq = iscsit_get_seq_holder(cmd, r2t->offset,
					r2t->xfer_len);
			if (!seq) {
				spin_unlock_bh(&cmd->r2t_lock);
				return -1;
			}

			cmd->write_data_done -=
					(seq->offset - seq->orig_offset);
			seq->data_sn = 0;
			seq->offset = seq->orig_offset;
			seq->next_burst_len = 0;
			seq->status = DATAOUT_SEQUENCE_WITHIN_COMMAND_RECOVERY;

			cmd->seq_send_order--;

			if (conn->sess->sess_ops->DataPDUInOrder)
				goto next;

			for (i = 0; i < seq->pdu_count; i++) {
				pdu = &cmd->pdu_list[i+seq->pdu_start];

				if (pdu->status != ISCSI_PDU_RECEIVED_OK)
					continue;

				pdu->status = ISCSI_PDU_NOT_RECEIVED;
			}
		}

next:
		cmd->outstanding_r2ts--;
	}
	spin_unlock_bh(&cmd->r2t_lock);

	/*
	 * We now drop all unacknowledged R2Ts, ie: ExpDataSN from TMR
	 * TASK_REASSIGN to the last R2T in the list..  We are also careful
	 * to check that the Initiator is not requesting R2Ts for DataOUT
	 * sequences it has already completed.
	 *
	 * Free each R2T in question and adjust values in struct iscsi_cmd
	 * accordingly so iscsit_build_r2ts_for_cmd() do the rest of
	 * the work after the TMR TASK_REASSIGN Response is sent.
	 */
drop_unacknowledged_r2ts:

	cmd->cmd_flags &= ~ICF_SENT_LAST_R2T;
	cmd->r2t_sn = tmr_req->exp_data_sn;

	spin_lock_bh(&cmd->r2t_lock);
	list_for_each_entry_safe(r2t, r2t_tmp, &cmd->cmd_r2t_list, r2t_list) {
		/*
		 * Skip up to the R2T Sequence number provided by the
		 * iSCSI TASK_REASSIGN TMR
		 */
		if (r2t->r2t_sn < tmr_req->exp_data_sn)
			continue;

		if (r2t->seq_complete) {
			pr_err("Initiator is requesting R2Ts from"
				" R2TSN: 0x%08x, but R2TSN: 0x%08x, Offset: %u,"
				" Length: %u is already complete."
				"   BAD INITIATOR ERL=2 IMPLEMENTATION!\n",
				tmr_req->exp_data_sn, r2t->r2t_sn,
				r2t->offset, r2t->xfer_len);
			spin_unlock_bh(&cmd->r2t_lock);
			return -1;
		}

		if (r2t->recovery_r2t) {
			iscsit_free_r2t(r2t, cmd);
			continue;
		}

		/*		   DataSequenceInOrder=Yes:
		 *
		 * Taking into account the iSCSI implementation requirement of
		 * MaxOutstandingR2T=1 while ErrorRecoveryLevel>0 and
		 * DataSequenceInOrder=Yes, it's safe to subtract the R2Ts
		 * entire transfer length from the commands R2T offset marker.
		 *
		 *		   DataSequenceInOrder=No:
		 *
		 * We subtract the difference from struct iscsi_seq between the
		 * current offset and original offset from cmd->write_data_done
		 * for account for DataOUT PDUs already received.  Then reset
		 * the current offset to the original and zero out the current
		 * burst length,  to make sure we re-request the entire DataOUT
		 * sequence.
		 */
		if (conn->sess->sess_ops->DataSequenceInOrder)
			cmd->r2t_offset -= r2t->xfer_len;
		else
			cmd->seq_send_order--;

		cmd->outstanding_r2ts--;
		iscsit_free_r2t(r2t, cmd);
	}
	spin_unlock_bh(&cmd->r2t_lock);

	return 0;
}

/*
 *	Performs sanity checks TMR TASK_REASSIGN's ExpDataSN for
 *	a given struct iscsi_cmd.
 */
int iscsit_check_task_reassign_expdatasn(
	struct iscsi_tmr_req *tmr_req,
	struct iscsi_conn *conn)
{
	struct iscsi_cmd *ref_cmd = tmr_req->ref_cmd;

	if (ref_cmd->iscsi_opcode != ISCSI_OP_SCSI_CMD)
		return 0;

	if (ref_cmd->se_cmd.se_cmd_flags & SCF_SENT_CHECK_CONDITION)
		return 0;

	if (ref_cmd->data_direction == DMA_NONE)
		return 0;

	/*
	 * For READs the TMR TASK_REASSIGNs ExpDataSN contains the next DataSN
	 * of DataIN the Initiator is expecting.
	 *
	 * Also check that the Initiator is not re-requesting DataIN that has
	 * already been acknowledged with a DataAck SNACK.
	 */
	if (ref_cmd->data_direction == DMA_FROM_DEVICE) {
		if (tmr_req->exp_data_sn > ref_cmd->data_sn) {
			pr_err("Received ExpDataSN: 0x%08x for READ"
				" in TMR TASK_REASSIGN greater than command's"
				" DataSN: 0x%08x.\n", tmr_req->exp_data_sn,
				ref_cmd->data_sn);
			return -1;
		}
		if ((ref_cmd->cmd_flags & ICF_GOT_DATACK_SNACK) &&
		    (tmr_req->exp_data_sn <= ref_cmd->acked_data_sn)) {
			pr_err("Received ExpDataSN: 0x%08x for READ"
				" in TMR TASK_REASSIGN for previously"
				" acknowledged DataIN: 0x%08x,"
				" protocol error\n", tmr_req->exp_data_sn,
				ref_cmd->acked_data_sn);
			return -1;
		}
		return iscsit_task_reassign_prepare_read(tmr_req, conn);
	}

	/*
	 * For WRITEs the TMR TASK_REASSIGNs ExpDataSN contains the next R2TSN
	 * for R2Ts the Initiator is expecting.
	 *
	 * Do the magic in iscsit_task_reassign_prepare_write().
	 */
	if (ref_cmd->data_direction == DMA_TO_DEVICE) {
		if (tmr_req->exp_data_sn > ref_cmd->r2t_sn) {
			pr_err("Received ExpDataSN: 0x%08x for WRITE"
				" in TMR TASK_REASSIGN greater than command's"
				" R2TSN: 0x%08x.\n", tmr_req->exp_data_sn,
					ref_cmd->r2t_sn);
			return -1;
		}
		return iscsit_task_reassign_prepare_write(tmr_req, conn);
	}

	pr_err("Unknown iSCSI data_direction: 0x%02x\n",
			ref_cmd->data_direction);

	return -1;
}