xref: /linux/drivers/target/iscsi/iscsi_target_erl0.c (revision 0d456bad36d42d16022be045c8a53ddbb59ee478)
1 /******************************************************************************
2  * This file contains error recovery level zero functions used by
3  * the iSCSI Target driver.
4  *
5  * \u00a9 Copyright 2007-2011 RisingTide Systems LLC.
6  *
7  * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
8  *
9  * Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
10  *
11  * This program is free software; you can redistribute it and/or modify
12  * it under the terms of the GNU General Public License as published by
13  * the Free Software Foundation; either version 2 of the License, or
14  * (at your option) any later version.
15  *
16  * This program is distributed in the hope that it will be useful,
17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  * GNU General Public License for more details.
20  ******************************************************************************/
21 
22 #include <scsi/iscsi_proto.h>
23 #include <target/target_core_base.h>
24 #include <target/target_core_fabric.h>
25 
26 #include "iscsi_target_core.h"
27 #include "iscsi_target_seq_pdu_list.h"
28 #include "iscsi_target_tq.h"
29 #include "iscsi_target_erl0.h"
30 #include "iscsi_target_erl1.h"
31 #include "iscsi_target_erl2.h"
32 #include "iscsi_target_util.h"
33 #include "iscsi_target.h"
34 
35 /*
36  *	Used to set values in struct iscsi_cmd that iscsit_dataout_check_sequence()
37  *	checks against to determine a PDU's Offset+Length is within the current
38  *	DataOUT Sequence.  Used for DataSequenceInOrder=Yes only.
39  */
40 void iscsit_set_dataout_sequence_values(
41 	struct iscsi_cmd *cmd)
42 {
43 	struct iscsi_conn *conn = cmd->conn;
44 	/*
45 	 * Still set seq_start_offset and seq_end_offset for Unsolicited
46 	 * DataOUT, even if DataSequenceInOrder=No.
47 	 */
48 	if (cmd->unsolicited_data) {
49 		cmd->seq_start_offset = cmd->write_data_done;
50 		cmd->seq_end_offset = (cmd->write_data_done +
51 			((cmd->se_cmd.data_length >
52 			  conn->sess->sess_ops->FirstBurstLength) ?
53 			 conn->sess->sess_ops->FirstBurstLength : cmd->se_cmd.data_length));
54 		return;
55 	}
56 
57 	if (!conn->sess->sess_ops->DataSequenceInOrder)
58 		return;
59 
60 	if (!cmd->seq_start_offset && !cmd->seq_end_offset) {
61 		cmd->seq_start_offset = cmd->write_data_done;
62 		cmd->seq_end_offset = (cmd->se_cmd.data_length >
63 			conn->sess->sess_ops->MaxBurstLength) ?
64 			(cmd->write_data_done +
65 			conn->sess->sess_ops->MaxBurstLength) : cmd->se_cmd.data_length;
66 	} else {
67 		cmd->seq_start_offset = cmd->seq_end_offset;
68 		cmd->seq_end_offset = ((cmd->seq_end_offset +
69 			conn->sess->sess_ops->MaxBurstLength) >=
70 			cmd->se_cmd.data_length) ? cmd->se_cmd.data_length :
71 			(cmd->seq_end_offset +
72 			 conn->sess->sess_ops->MaxBurstLength);
73 	}
74 }
75 
76 static int iscsit_dataout_within_command_recovery_check(
77 	struct iscsi_cmd *cmd,
78 	unsigned char *buf)
79 {
80 	struct iscsi_conn *conn = cmd->conn;
81 	struct iscsi_data *hdr = (struct iscsi_data *) buf;
82 	u32 payload_length = ntoh24(hdr->dlength);
83 
84 	/*
85 	 * We do the within-command recovery checks here as it is
86 	 * the first function called in iscsi_check_pre_dataout().
87 	 * Basically, if we are in within-command recovery and
88 	 * the PDU does not contain the offset the sequence needs,
89 	 * dump the payload.
90 	 *
91 	 * This only applies to DataPDUInOrder=Yes, for
92 	 * DataPDUInOrder=No we only re-request the failed PDU
93 	 * and check that all PDUs in a sequence are received
94 	 * upon end of sequence.
95 	 */
96 	if (conn->sess->sess_ops->DataSequenceInOrder) {
97 		if ((cmd->cmd_flags & ICF_WITHIN_COMMAND_RECOVERY) &&
98 		    cmd->write_data_done != be32_to_cpu(hdr->offset))
99 			goto dump;
100 
101 		cmd->cmd_flags &= ~ICF_WITHIN_COMMAND_RECOVERY;
102 	} else {
103 		struct iscsi_seq *seq;
104 
105 		seq = iscsit_get_seq_holder(cmd, be32_to_cpu(hdr->offset),
106 					    payload_length);
107 		if (!seq)
108 			return DATAOUT_CANNOT_RECOVER;
109 		/*
110 		 * Set the struct iscsi_seq pointer to reuse later.
111 		 */
112 		cmd->seq_ptr = seq;
113 
114 		if (conn->sess->sess_ops->DataPDUInOrder) {
115 			if (seq->status ==
116 			    DATAOUT_SEQUENCE_WITHIN_COMMAND_RECOVERY &&
117 			   (seq->offset != be32_to_cpu(hdr->offset) ||
118 			    seq->data_sn != be32_to_cpu(hdr->datasn)))
119 				goto dump;
120 		} else {
121 			if (seq->status ==
122 			     DATAOUT_SEQUENCE_WITHIN_COMMAND_RECOVERY &&
123 			    seq->data_sn != be32_to_cpu(hdr->datasn))
124 				goto dump;
125 		}
126 
127 		if (seq->status == DATAOUT_SEQUENCE_COMPLETE)
128 			goto dump;
129 
130 		if (seq->status != DATAOUT_SEQUENCE_COMPLETE)
131 			seq->status = 0;
132 	}
133 
134 	return DATAOUT_NORMAL;
135 
136 dump:
137 	pr_err("Dumping DataOUT PDU Offset: %u Length: %d DataSN:"
138 		" 0x%08x\n", hdr->offset, payload_length, hdr->datasn);
139 	return iscsit_dump_data_payload(conn, payload_length, 1);
140 }
141 
142 static int iscsit_dataout_check_unsolicited_sequence(
143 	struct iscsi_cmd *cmd,
144 	unsigned char *buf)
145 {
146 	u32 first_burst_len;
147 	struct iscsi_conn *conn = cmd->conn;
148 	struct iscsi_data *hdr = (struct iscsi_data *) buf;
149 	u32 payload_length = ntoh24(hdr->dlength);
150 
151 
152 	if ((be32_to_cpu(hdr->offset) < cmd->seq_start_offset) ||
153 	   ((be32_to_cpu(hdr->offset) + payload_length) > cmd->seq_end_offset)) {
154 		pr_err("Command ITT: 0x%08x with Offset: %u,"
155 		" Length: %u outside of Unsolicited Sequence %u:%u while"
156 		" DataSequenceInOrder=Yes.\n", cmd->init_task_tag,
157 		be32_to_cpu(hdr->offset), payload_length, cmd->seq_start_offset,
158 			cmd->seq_end_offset);
159 		return DATAOUT_CANNOT_RECOVER;
160 	}
161 
162 	first_burst_len = (cmd->first_burst_len + payload_length);
163 
164 	if (first_burst_len > conn->sess->sess_ops->FirstBurstLength) {
165 		pr_err("Total %u bytes exceeds FirstBurstLength: %u"
166 			" for this Unsolicited DataOut Burst.\n",
167 			first_burst_len, conn->sess->sess_ops->FirstBurstLength);
168 		transport_send_check_condition_and_sense(&cmd->se_cmd,
169 				TCM_INCORRECT_AMOUNT_OF_DATA, 0);
170 		return DATAOUT_CANNOT_RECOVER;
171 	}
172 
173 	/*
174 	 * Perform various MaxBurstLength and ISCSI_FLAG_CMD_FINAL sanity
175 	 * checks for the current Unsolicited DataOUT Sequence.
176 	 */
177 	if (hdr->flags & ISCSI_FLAG_CMD_FINAL) {
178 		/*
179 		 * Ignore ISCSI_FLAG_CMD_FINAL checks while DataPDUInOrder=No, end of
180 		 * sequence checks are handled in
181 		 * iscsit_dataout_datapduinorder_no_fbit().
182 		 */
183 		if (!conn->sess->sess_ops->DataPDUInOrder)
184 			goto out;
185 
186 		if ((first_burst_len != cmd->se_cmd.data_length) &&
187 		    (first_burst_len != conn->sess->sess_ops->FirstBurstLength)) {
188 			pr_err("Unsolicited non-immediate data"
189 			" received %u does not equal FirstBurstLength: %u, and"
190 			" does not equal ExpXferLen %u.\n", first_burst_len,
191 				conn->sess->sess_ops->FirstBurstLength,
192 				cmd->se_cmd.data_length);
193 			transport_send_check_condition_and_sense(&cmd->se_cmd,
194 					TCM_INCORRECT_AMOUNT_OF_DATA, 0);
195 			return DATAOUT_CANNOT_RECOVER;
196 		}
197 	} else {
198 		if (first_burst_len == conn->sess->sess_ops->FirstBurstLength) {
199 			pr_err("Command ITT: 0x%08x reached"
200 			" FirstBurstLength: %u, but ISCSI_FLAG_CMD_FINAL is not set. protocol"
201 				" error.\n", cmd->init_task_tag,
202 				conn->sess->sess_ops->FirstBurstLength);
203 			return DATAOUT_CANNOT_RECOVER;
204 		}
205 		if (first_burst_len == cmd->se_cmd.data_length) {
206 			pr_err("Command ITT: 0x%08x reached"
207 			" ExpXferLen: %u, but ISCSI_FLAG_CMD_FINAL is not set. protocol"
208 			" error.\n", cmd->init_task_tag, cmd->se_cmd.data_length);
209 			return DATAOUT_CANNOT_RECOVER;
210 		}
211 	}
212 
213 out:
214 	return DATAOUT_NORMAL;
215 }
216 
217 static int iscsit_dataout_check_sequence(
218 	struct iscsi_cmd *cmd,
219 	unsigned char *buf)
220 {
221 	u32 next_burst_len;
222 	struct iscsi_conn *conn = cmd->conn;
223 	struct iscsi_seq *seq = NULL;
224 	struct iscsi_data *hdr = (struct iscsi_data *) buf;
225 	u32 payload_length = ntoh24(hdr->dlength);
226 
227 	/*
228 	 * For DataSequenceInOrder=Yes: Check that the offset and offset+length
229 	 * is within range as defined by iscsi_set_dataout_sequence_values().
230 	 *
231 	 * For DataSequenceInOrder=No: Check that an struct iscsi_seq exists for
232 	 * offset+length tuple.
233 	 */
234 	if (conn->sess->sess_ops->DataSequenceInOrder) {
235 		/*
236 		 * Due to possibility of recovery DataOUT sent by the initiator
237 		 * fullfilling an Recovery R2T, it's best to just dump the
238 		 * payload here, instead of erroring out.
239 		 */
240 		if ((be32_to_cpu(hdr->offset) < cmd->seq_start_offset) ||
241 		   ((be32_to_cpu(hdr->offset) + payload_length) > cmd->seq_end_offset)) {
242 			pr_err("Command ITT: 0x%08x with Offset: %u,"
243 			" Length: %u outside of Sequence %u:%u while"
244 			" DataSequenceInOrder=Yes.\n", cmd->init_task_tag,
245 			be32_to_cpu(hdr->offset), payload_length, cmd->seq_start_offset,
246 				cmd->seq_end_offset);
247 
248 			if (iscsit_dump_data_payload(conn, payload_length, 1) < 0)
249 				return DATAOUT_CANNOT_RECOVER;
250 			return DATAOUT_WITHIN_COMMAND_RECOVERY;
251 		}
252 
253 		next_burst_len = (cmd->next_burst_len + payload_length);
254 	} else {
255 		seq = iscsit_get_seq_holder(cmd, be32_to_cpu(hdr->offset),
256 					    payload_length);
257 		if (!seq)
258 			return DATAOUT_CANNOT_RECOVER;
259 		/*
260 		 * Set the struct iscsi_seq pointer to reuse later.
261 		 */
262 		cmd->seq_ptr = seq;
263 
264 		if (seq->status == DATAOUT_SEQUENCE_COMPLETE) {
265 			if (iscsit_dump_data_payload(conn, payload_length, 1) < 0)
266 				return DATAOUT_CANNOT_RECOVER;
267 			return DATAOUT_WITHIN_COMMAND_RECOVERY;
268 		}
269 
270 		next_burst_len = (seq->next_burst_len + payload_length);
271 	}
272 
273 	if (next_burst_len > conn->sess->sess_ops->MaxBurstLength) {
274 		pr_err("Command ITT: 0x%08x, NextBurstLength: %u and"
275 			" Length: %u exceeds MaxBurstLength: %u. protocol"
276 			" error.\n", cmd->init_task_tag,
277 			(next_burst_len - payload_length),
278 			payload_length, conn->sess->sess_ops->MaxBurstLength);
279 		return DATAOUT_CANNOT_RECOVER;
280 	}
281 
282 	/*
283 	 * Perform various MaxBurstLength and ISCSI_FLAG_CMD_FINAL sanity
284 	 * checks for the current DataOUT Sequence.
285 	 */
286 	if (hdr->flags & ISCSI_FLAG_CMD_FINAL) {
287 		/*
288 		 * Ignore ISCSI_FLAG_CMD_FINAL checks while DataPDUInOrder=No, end of
289 		 * sequence checks are handled in
290 		 * iscsit_dataout_datapduinorder_no_fbit().
291 		 */
292 		if (!conn->sess->sess_ops->DataPDUInOrder)
293 			goto out;
294 
295 		if (conn->sess->sess_ops->DataSequenceInOrder) {
296 			if ((next_burst_len <
297 			     conn->sess->sess_ops->MaxBurstLength) &&
298 			   ((cmd->write_data_done + payload_length) <
299 			     cmd->se_cmd.data_length)) {
300 				pr_err("Command ITT: 0x%08x set ISCSI_FLAG_CMD_FINAL"
301 				" before end of DataOUT sequence, protocol"
302 				" error.\n", cmd->init_task_tag);
303 				return DATAOUT_CANNOT_RECOVER;
304 			}
305 		} else {
306 			if (next_burst_len < seq->xfer_len) {
307 				pr_err("Command ITT: 0x%08x set ISCSI_FLAG_CMD_FINAL"
308 				" before end of DataOUT sequence, protocol"
309 				" error.\n", cmd->init_task_tag);
310 				return DATAOUT_CANNOT_RECOVER;
311 			}
312 		}
313 	} else {
314 		if (conn->sess->sess_ops->DataSequenceInOrder) {
315 			if (next_burst_len ==
316 					conn->sess->sess_ops->MaxBurstLength) {
317 				pr_err("Command ITT: 0x%08x reached"
318 				" MaxBurstLength: %u, but ISCSI_FLAG_CMD_FINAL is"
319 				" not set, protocol error.", cmd->init_task_tag,
320 					conn->sess->sess_ops->MaxBurstLength);
321 				return DATAOUT_CANNOT_RECOVER;
322 			}
323 			if ((cmd->write_data_done + payload_length) ==
324 					cmd->se_cmd.data_length) {
325 				pr_err("Command ITT: 0x%08x reached"
326 				" last DataOUT PDU in sequence but ISCSI_FLAG_"
327 				"CMD_FINAL is not set, protocol error.\n",
328 					cmd->init_task_tag);
329 				return DATAOUT_CANNOT_RECOVER;
330 			}
331 		} else {
332 			if (next_burst_len == seq->xfer_len) {
333 				pr_err("Command ITT: 0x%08x reached"
334 				" last DataOUT PDU in sequence but ISCSI_FLAG_"
335 				"CMD_FINAL is not set, protocol error.\n",
336 					cmd->init_task_tag);
337 				return DATAOUT_CANNOT_RECOVER;
338 			}
339 		}
340 	}
341 
342 out:
343 	return DATAOUT_NORMAL;
344 }
345 
346 static int iscsit_dataout_check_datasn(
347 	struct iscsi_cmd *cmd,
348 	unsigned char *buf)
349 {
350 	int dump = 0, recovery = 0;
351 	u32 data_sn = 0;
352 	struct iscsi_conn *conn = cmd->conn;
353 	struct iscsi_data *hdr = (struct iscsi_data *) buf;
354 	u32 payload_length = ntoh24(hdr->dlength);
355 
356 	/*
357 	 * Considering the target has no method of re-requesting DataOUT
358 	 * by DataSN, if we receieve a greater DataSN than expected we
359 	 * assume the functions for DataPDUInOrder=[Yes,No] below will
360 	 * handle it.
361 	 *
362 	 * If the DataSN is less than expected, dump the payload.
363 	 */
364 	if (conn->sess->sess_ops->DataSequenceInOrder)
365 		data_sn = cmd->data_sn;
366 	else {
367 		struct iscsi_seq *seq = cmd->seq_ptr;
368 		data_sn = seq->data_sn;
369 	}
370 
371 	if (be32_to_cpu(hdr->datasn) > data_sn) {
372 		pr_err("Command ITT: 0x%08x, received DataSN: 0x%08x"
373 			" higher than expected 0x%08x.\n", cmd->init_task_tag,
374 				be32_to_cpu(hdr->datasn), data_sn);
375 		recovery = 1;
376 		goto recover;
377 	} else if (be32_to_cpu(hdr->datasn) < data_sn) {
378 		pr_err("Command ITT: 0x%08x, received DataSN: 0x%08x"
379 			" lower than expected 0x%08x, discarding payload.\n",
380 			cmd->init_task_tag, be32_to_cpu(hdr->datasn), data_sn);
381 		dump = 1;
382 		goto dump;
383 	}
384 
385 	return DATAOUT_NORMAL;
386 
387 recover:
388 	if (!conn->sess->sess_ops->ErrorRecoveryLevel) {
389 		pr_err("Unable to perform within-command recovery"
390 				" while ERL=0.\n");
391 		return DATAOUT_CANNOT_RECOVER;
392 	}
393 dump:
394 	if (iscsit_dump_data_payload(conn, payload_length, 1) < 0)
395 		return DATAOUT_CANNOT_RECOVER;
396 
397 	return (recovery || dump) ? DATAOUT_WITHIN_COMMAND_RECOVERY :
398 				DATAOUT_NORMAL;
399 }
400 
401 static int iscsit_dataout_pre_datapduinorder_yes(
402 	struct iscsi_cmd *cmd,
403 	unsigned char *buf)
404 {
405 	int dump = 0, recovery = 0;
406 	struct iscsi_conn *conn = cmd->conn;
407 	struct iscsi_data *hdr = (struct iscsi_data *) buf;
408 	u32 payload_length = ntoh24(hdr->dlength);
409 
410 	/*
411 	 * For DataSequenceInOrder=Yes: If the offset is greater than the global
412 	 * DataPDUInOrder=Yes offset counter in struct iscsi_cmd a protcol error has
413 	 * occurred and fail the connection.
414 	 *
415 	 * For DataSequenceInOrder=No: If the offset is greater than the per
416 	 * sequence DataPDUInOrder=Yes offset counter in struct iscsi_seq a protocol
417 	 * error has occurred and fail the connection.
418 	 */
419 	if (conn->sess->sess_ops->DataSequenceInOrder) {
420 		if (be32_to_cpu(hdr->offset) != cmd->write_data_done) {
421 			pr_err("Command ITT: 0x%08x, received offset"
422 			" %u different than expected %u.\n", cmd->init_task_tag,
423 				be32_to_cpu(hdr->offset), cmd->write_data_done);
424 			recovery = 1;
425 			goto recover;
426 		}
427 	} else {
428 		struct iscsi_seq *seq = cmd->seq_ptr;
429 
430 		if (be32_to_cpu(hdr->offset) > seq->offset) {
431 			pr_err("Command ITT: 0x%08x, received offset"
432 			" %u greater than expected %u.\n", cmd->init_task_tag,
433 				be32_to_cpu(hdr->offset), seq->offset);
434 			recovery = 1;
435 			goto recover;
436 		} else if (be32_to_cpu(hdr->offset) < seq->offset) {
437 			pr_err("Command ITT: 0x%08x, received offset"
438 			" %u less than expected %u, discarding payload.\n",
439 				cmd->init_task_tag, be32_to_cpu(hdr->offset),
440 				seq->offset);
441 			dump = 1;
442 			goto dump;
443 		}
444 	}
445 
446 	return DATAOUT_NORMAL;
447 
448 recover:
449 	if (!conn->sess->sess_ops->ErrorRecoveryLevel) {
450 		pr_err("Unable to perform within-command recovery"
451 				" while ERL=0.\n");
452 		return DATAOUT_CANNOT_RECOVER;
453 	}
454 dump:
455 	if (iscsit_dump_data_payload(conn, payload_length, 1) < 0)
456 		return DATAOUT_CANNOT_RECOVER;
457 
458 	return (recovery) ? iscsit_recover_dataout_sequence(cmd,
459 		be32_to_cpu(hdr->offset), payload_length) :
460 	       (dump) ? DATAOUT_WITHIN_COMMAND_RECOVERY : DATAOUT_NORMAL;
461 }
462 
463 static int iscsit_dataout_pre_datapduinorder_no(
464 	struct iscsi_cmd *cmd,
465 	unsigned char *buf)
466 {
467 	struct iscsi_pdu *pdu;
468 	struct iscsi_data *hdr = (struct iscsi_data *) buf;
469 	u32 payload_length = ntoh24(hdr->dlength);
470 
471 	pdu = iscsit_get_pdu_holder(cmd, be32_to_cpu(hdr->offset),
472 				    payload_length);
473 	if (!pdu)
474 		return DATAOUT_CANNOT_RECOVER;
475 
476 	cmd->pdu_ptr = pdu;
477 
478 	switch (pdu->status) {
479 	case ISCSI_PDU_NOT_RECEIVED:
480 	case ISCSI_PDU_CRC_FAILED:
481 	case ISCSI_PDU_TIMED_OUT:
482 		break;
483 	case ISCSI_PDU_RECEIVED_OK:
484 		pr_err("Command ITT: 0x%08x received already gotten"
485 			" Offset: %u, Length: %u\n", cmd->init_task_tag,
486 				be32_to_cpu(hdr->offset), payload_length);
487 		return iscsit_dump_data_payload(cmd->conn, payload_length, 1);
488 	default:
489 		return DATAOUT_CANNOT_RECOVER;
490 	}
491 
492 	return DATAOUT_NORMAL;
493 }
494 
495 static int iscsit_dataout_update_r2t(struct iscsi_cmd *cmd, u32 offset, u32 length)
496 {
497 	struct iscsi_r2t *r2t;
498 
499 	if (cmd->unsolicited_data)
500 		return 0;
501 
502 	r2t = iscsit_get_r2t_for_eos(cmd, offset, length);
503 	if (!r2t)
504 		return -1;
505 
506 	spin_lock_bh(&cmd->r2t_lock);
507 	r2t->seq_complete = 1;
508 	cmd->outstanding_r2ts--;
509 	spin_unlock_bh(&cmd->r2t_lock);
510 
511 	return 0;
512 }
513 
514 static int iscsit_dataout_update_datapduinorder_no(
515 	struct iscsi_cmd *cmd,
516 	u32 data_sn,
517 	int f_bit)
518 {
519 	int ret = 0;
520 	struct iscsi_pdu *pdu = cmd->pdu_ptr;
521 
522 	pdu->data_sn = data_sn;
523 
524 	switch (pdu->status) {
525 	case ISCSI_PDU_NOT_RECEIVED:
526 		pdu->status = ISCSI_PDU_RECEIVED_OK;
527 		break;
528 	case ISCSI_PDU_CRC_FAILED:
529 		pdu->status = ISCSI_PDU_RECEIVED_OK;
530 		break;
531 	case ISCSI_PDU_TIMED_OUT:
532 		pdu->status = ISCSI_PDU_RECEIVED_OK;
533 		break;
534 	default:
535 		return DATAOUT_CANNOT_RECOVER;
536 	}
537 
538 	if (f_bit) {
539 		ret = iscsit_dataout_datapduinorder_no_fbit(cmd, pdu);
540 		if (ret == DATAOUT_CANNOT_RECOVER)
541 			return ret;
542 	}
543 
544 	return DATAOUT_NORMAL;
545 }
546 
547 static int iscsit_dataout_post_crc_passed(
548 	struct iscsi_cmd *cmd,
549 	unsigned char *buf)
550 {
551 	int ret, send_r2t = 0;
552 	struct iscsi_conn *conn = cmd->conn;
553 	struct iscsi_seq *seq = NULL;
554 	struct iscsi_data *hdr = (struct iscsi_data *) buf;
555 	u32 payload_length = ntoh24(hdr->dlength);
556 
557 	if (cmd->unsolicited_data) {
558 		if ((cmd->first_burst_len + payload_length) ==
559 		     conn->sess->sess_ops->FirstBurstLength) {
560 			if (iscsit_dataout_update_r2t(cmd, be32_to_cpu(hdr->offset),
561 					payload_length) < 0)
562 				return DATAOUT_CANNOT_RECOVER;
563 			send_r2t = 1;
564 		}
565 
566 		if (!conn->sess->sess_ops->DataPDUInOrder) {
567 			ret = iscsit_dataout_update_datapduinorder_no(cmd,
568 				be32_to_cpu(hdr->datasn),
569 				(hdr->flags & ISCSI_FLAG_CMD_FINAL));
570 			if (ret == DATAOUT_CANNOT_RECOVER)
571 				return ret;
572 		}
573 
574 		cmd->first_burst_len += payload_length;
575 
576 		if (conn->sess->sess_ops->DataSequenceInOrder)
577 			cmd->data_sn++;
578 		else {
579 			seq = cmd->seq_ptr;
580 			seq->data_sn++;
581 			seq->offset += payload_length;
582 		}
583 
584 		if (send_r2t) {
585 			if (seq)
586 				seq->status = DATAOUT_SEQUENCE_COMPLETE;
587 			cmd->first_burst_len = 0;
588 			cmd->unsolicited_data = 0;
589 		}
590 	} else {
591 		if (conn->sess->sess_ops->DataSequenceInOrder) {
592 			if ((cmd->next_burst_len + payload_length) ==
593 			     conn->sess->sess_ops->MaxBurstLength) {
594 				if (iscsit_dataout_update_r2t(cmd,
595 						be32_to_cpu(hdr->offset),
596 						payload_length) < 0)
597 					return DATAOUT_CANNOT_RECOVER;
598 				send_r2t = 1;
599 			}
600 
601 			if (!conn->sess->sess_ops->DataPDUInOrder) {
602 				ret = iscsit_dataout_update_datapduinorder_no(
603 						cmd, be32_to_cpu(hdr->datasn),
604 						(hdr->flags & ISCSI_FLAG_CMD_FINAL));
605 				if (ret == DATAOUT_CANNOT_RECOVER)
606 					return ret;
607 			}
608 
609 			cmd->next_burst_len += payload_length;
610 			cmd->data_sn++;
611 
612 			if (send_r2t)
613 				cmd->next_burst_len = 0;
614 		} else {
615 			seq = cmd->seq_ptr;
616 
617 			if ((seq->next_burst_len + payload_length) ==
618 			     seq->xfer_len) {
619 				if (iscsit_dataout_update_r2t(cmd,
620 						be32_to_cpu(hdr->offset),
621 						payload_length) < 0)
622 					return DATAOUT_CANNOT_RECOVER;
623 				send_r2t = 1;
624 			}
625 
626 			if (!conn->sess->sess_ops->DataPDUInOrder) {
627 				ret = iscsit_dataout_update_datapduinorder_no(
628 						cmd, be32_to_cpu(hdr->datasn),
629 						(hdr->flags & ISCSI_FLAG_CMD_FINAL));
630 				if (ret == DATAOUT_CANNOT_RECOVER)
631 					return ret;
632 			}
633 
634 			seq->data_sn++;
635 			seq->offset += payload_length;
636 			seq->next_burst_len += payload_length;
637 
638 			if (send_r2t) {
639 				seq->next_burst_len = 0;
640 				seq->status = DATAOUT_SEQUENCE_COMPLETE;
641 			}
642 		}
643 	}
644 
645 	if (send_r2t && conn->sess->sess_ops->DataSequenceInOrder)
646 		cmd->data_sn = 0;
647 
648 	cmd->write_data_done += payload_length;
649 
650 	if (cmd->write_data_done == cmd->se_cmd.data_length)
651 		return DATAOUT_SEND_TO_TRANSPORT;
652 	else if (send_r2t)
653 		return DATAOUT_SEND_R2T;
654 	else
655 		return DATAOUT_NORMAL;
656 }
657 
658 static int iscsit_dataout_post_crc_failed(
659 	struct iscsi_cmd *cmd,
660 	unsigned char *buf)
661 {
662 	struct iscsi_conn *conn = cmd->conn;
663 	struct iscsi_pdu *pdu;
664 	struct iscsi_data *hdr = (struct iscsi_data *) buf;
665 	u32 payload_length = ntoh24(hdr->dlength);
666 
667 	if (conn->sess->sess_ops->DataPDUInOrder)
668 		goto recover;
669 	/*
670 	 * The rest of this function is only called when DataPDUInOrder=No.
671 	 */
672 	pdu = cmd->pdu_ptr;
673 
674 	switch (pdu->status) {
675 	case ISCSI_PDU_NOT_RECEIVED:
676 		pdu->status = ISCSI_PDU_CRC_FAILED;
677 		break;
678 	case ISCSI_PDU_CRC_FAILED:
679 		break;
680 	case ISCSI_PDU_TIMED_OUT:
681 		pdu->status = ISCSI_PDU_CRC_FAILED;
682 		break;
683 	default:
684 		return DATAOUT_CANNOT_RECOVER;
685 	}
686 
687 recover:
688 	return iscsit_recover_dataout_sequence(cmd, be32_to_cpu(hdr->offset),
689 						payload_length);
690 }
691 
692 /*
693  *	Called from iscsit_handle_data_out() before DataOUT Payload is received
694  *	and CRC computed.
695  */
696 int iscsit_check_pre_dataout(
697 	struct iscsi_cmd *cmd,
698 	unsigned char *buf)
699 {
700 	int ret;
701 	struct iscsi_conn *conn = cmd->conn;
702 
703 	ret = iscsit_dataout_within_command_recovery_check(cmd, buf);
704 	if ((ret == DATAOUT_WITHIN_COMMAND_RECOVERY) ||
705 	    (ret == DATAOUT_CANNOT_RECOVER))
706 		return ret;
707 
708 	ret = iscsit_dataout_check_datasn(cmd, buf);
709 	if ((ret == DATAOUT_WITHIN_COMMAND_RECOVERY) ||
710 	    (ret == DATAOUT_CANNOT_RECOVER))
711 		return ret;
712 
713 	if (cmd->unsolicited_data) {
714 		ret = iscsit_dataout_check_unsolicited_sequence(cmd, buf);
715 		if ((ret == DATAOUT_WITHIN_COMMAND_RECOVERY) ||
716 		    (ret == DATAOUT_CANNOT_RECOVER))
717 			return ret;
718 	} else {
719 		ret = iscsit_dataout_check_sequence(cmd, buf);
720 		if ((ret == DATAOUT_WITHIN_COMMAND_RECOVERY) ||
721 		    (ret == DATAOUT_CANNOT_RECOVER))
722 			return ret;
723 	}
724 
725 	return (conn->sess->sess_ops->DataPDUInOrder) ?
726 		iscsit_dataout_pre_datapduinorder_yes(cmd, buf) :
727 		iscsit_dataout_pre_datapduinorder_no(cmd, buf);
728 }
729 
730 /*
731  *	Called from iscsit_handle_data_out() after DataOUT Payload is received
732  *	and CRC computed.
733  */
734 int iscsit_check_post_dataout(
735 	struct iscsi_cmd *cmd,
736 	unsigned char *buf,
737 	u8 data_crc_failed)
738 {
739 	struct iscsi_conn *conn = cmd->conn;
740 
741 	cmd->dataout_timeout_retries = 0;
742 
743 	if (!data_crc_failed)
744 		return iscsit_dataout_post_crc_passed(cmd, buf);
745 	else {
746 		if (!conn->sess->sess_ops->ErrorRecoveryLevel) {
747 			pr_err("Unable to recover from DataOUT CRC"
748 				" failure while ERL=0, closing session.\n");
749 			iscsit_add_reject_from_cmd(ISCSI_REASON_DATA_DIGEST_ERROR,
750 					1, 0, buf, cmd);
751 			return DATAOUT_CANNOT_RECOVER;
752 		}
753 
754 		iscsit_add_reject_from_cmd(ISCSI_REASON_DATA_DIGEST_ERROR,
755 				0, 0, buf, cmd);
756 		return iscsit_dataout_post_crc_failed(cmd, buf);
757 	}
758 }
759 
760 static void iscsit_handle_time2retain_timeout(unsigned long data)
761 {
762 	struct iscsi_session *sess = (struct iscsi_session *) data;
763 	struct iscsi_portal_group *tpg = ISCSI_TPG_S(sess);
764 	struct se_portal_group *se_tpg = &tpg->tpg_se_tpg;
765 
766 	spin_lock_bh(&se_tpg->session_lock);
767 	if (sess->time2retain_timer_flags & ISCSI_TF_STOP) {
768 		spin_unlock_bh(&se_tpg->session_lock);
769 		return;
770 	}
771 	if (atomic_read(&sess->session_reinstatement)) {
772 		pr_err("Exiting Time2Retain handler because"
773 				" session_reinstatement=1\n");
774 		spin_unlock_bh(&se_tpg->session_lock);
775 		return;
776 	}
777 	sess->time2retain_timer_flags |= ISCSI_TF_EXPIRED;
778 
779 	pr_err("Time2Retain timer expired for SID: %u, cleaning up"
780 			" iSCSI session.\n", sess->sid);
781 	{
782 	struct iscsi_tiqn *tiqn = tpg->tpg_tiqn;
783 
784 	if (tiqn) {
785 		spin_lock(&tiqn->sess_err_stats.lock);
786 		strcpy(tiqn->sess_err_stats.last_sess_fail_rem_name,
787 			(void *)sess->sess_ops->InitiatorName);
788 		tiqn->sess_err_stats.last_sess_failure_type =
789 				ISCSI_SESS_ERR_CXN_TIMEOUT;
790 		tiqn->sess_err_stats.cxn_timeout_errors++;
791 		sess->conn_timeout_errors++;
792 		spin_unlock(&tiqn->sess_err_stats.lock);
793 	}
794 	}
795 
796 	spin_unlock_bh(&se_tpg->session_lock);
797 	target_put_session(sess->se_sess);
798 }
799 
800 void iscsit_start_time2retain_handler(struct iscsi_session *sess)
801 {
802 	int tpg_active;
803 	/*
804 	 * Only start Time2Retain timer when the associated TPG is still in
805 	 * an ACTIVE (eg: not disabled or shutdown) state.
806 	 */
807 	spin_lock(&ISCSI_TPG_S(sess)->tpg_state_lock);
808 	tpg_active = (ISCSI_TPG_S(sess)->tpg_state == TPG_STATE_ACTIVE);
809 	spin_unlock(&ISCSI_TPG_S(sess)->tpg_state_lock);
810 
811 	if (!tpg_active)
812 		return;
813 
814 	if (sess->time2retain_timer_flags & ISCSI_TF_RUNNING)
815 		return;
816 
817 	pr_debug("Starting Time2Retain timer for %u seconds on"
818 		" SID: %u\n", sess->sess_ops->DefaultTime2Retain, sess->sid);
819 
820 	init_timer(&sess->time2retain_timer);
821 	sess->time2retain_timer.expires =
822 		(get_jiffies_64() + sess->sess_ops->DefaultTime2Retain * HZ);
823 	sess->time2retain_timer.data = (unsigned long)sess;
824 	sess->time2retain_timer.function = iscsit_handle_time2retain_timeout;
825 	sess->time2retain_timer_flags &= ~ISCSI_TF_STOP;
826 	sess->time2retain_timer_flags |= ISCSI_TF_RUNNING;
827 	add_timer(&sess->time2retain_timer);
828 }
829 
830 /*
831  *	Called with spin_lock_bh(&struct se_portal_group->session_lock) held
832  */
833 int iscsit_stop_time2retain_timer(struct iscsi_session *sess)
834 {
835 	struct iscsi_portal_group *tpg = ISCSI_TPG_S(sess);
836 	struct se_portal_group *se_tpg = &tpg->tpg_se_tpg;
837 
838 	if (sess->time2retain_timer_flags & ISCSI_TF_EXPIRED)
839 		return -1;
840 
841 	if (!(sess->time2retain_timer_flags & ISCSI_TF_RUNNING))
842 		return 0;
843 
844 	sess->time2retain_timer_flags |= ISCSI_TF_STOP;
845 	spin_unlock_bh(&se_tpg->session_lock);
846 
847 	del_timer_sync(&sess->time2retain_timer);
848 
849 	spin_lock_bh(&se_tpg->session_lock);
850 	sess->time2retain_timer_flags &= ~ISCSI_TF_RUNNING;
851 	pr_debug("Stopped Time2Retain Timer for SID: %u\n",
852 			sess->sid);
853 	return 0;
854 }
855 
856 void iscsit_connection_reinstatement_rcfr(struct iscsi_conn *conn)
857 {
858 	spin_lock_bh(&conn->state_lock);
859 	if (atomic_read(&conn->connection_exit)) {
860 		spin_unlock_bh(&conn->state_lock);
861 		goto sleep;
862 	}
863 
864 	if (atomic_read(&conn->transport_failed)) {
865 		spin_unlock_bh(&conn->state_lock);
866 		goto sleep;
867 	}
868 	spin_unlock_bh(&conn->state_lock);
869 
870 	iscsi_thread_set_force_reinstatement(conn);
871 
872 sleep:
873 	wait_for_completion(&conn->conn_wait_rcfr_comp);
874 	complete(&conn->conn_post_wait_comp);
875 }
876 
877 void iscsit_cause_connection_reinstatement(struct iscsi_conn *conn, int sleep)
878 {
879 	spin_lock_bh(&conn->state_lock);
880 	if (atomic_read(&conn->connection_exit)) {
881 		spin_unlock_bh(&conn->state_lock);
882 		return;
883 	}
884 
885 	if (atomic_read(&conn->transport_failed)) {
886 		spin_unlock_bh(&conn->state_lock);
887 		return;
888 	}
889 
890 	if (atomic_read(&conn->connection_reinstatement)) {
891 		spin_unlock_bh(&conn->state_lock);
892 		return;
893 	}
894 
895 	if (iscsi_thread_set_force_reinstatement(conn) < 0) {
896 		spin_unlock_bh(&conn->state_lock);
897 		return;
898 	}
899 
900 	atomic_set(&conn->connection_reinstatement, 1);
901 	if (!sleep) {
902 		spin_unlock_bh(&conn->state_lock);
903 		return;
904 	}
905 
906 	atomic_set(&conn->sleep_on_conn_wait_comp, 1);
907 	spin_unlock_bh(&conn->state_lock);
908 
909 	wait_for_completion(&conn->conn_wait_comp);
910 	complete(&conn->conn_post_wait_comp);
911 }
912 
913 void iscsit_fall_back_to_erl0(struct iscsi_session *sess)
914 {
915 	pr_debug("Falling back to ErrorRecoveryLevel=0 for SID:"
916 			" %u\n", sess->sid);
917 
918 	atomic_set(&sess->session_fall_back_to_erl0, 1);
919 }
920 
921 static void iscsit_handle_connection_cleanup(struct iscsi_conn *conn)
922 {
923 	struct iscsi_session *sess = conn->sess;
924 
925 	if ((sess->sess_ops->ErrorRecoveryLevel == 2) &&
926 	    !atomic_read(&sess->session_reinstatement) &&
927 	    !atomic_read(&sess->session_fall_back_to_erl0))
928 		iscsit_connection_recovery_transport_reset(conn);
929 	else {
930 		pr_debug("Performing cleanup for failed iSCSI"
931 			" Connection ID: %hu from %s\n", conn->cid,
932 			sess->sess_ops->InitiatorName);
933 		iscsit_close_connection(conn);
934 	}
935 }
936 
937 void iscsit_take_action_for_connection_exit(struct iscsi_conn *conn)
938 {
939 	spin_lock_bh(&conn->state_lock);
940 	if (atomic_read(&conn->connection_exit)) {
941 		spin_unlock_bh(&conn->state_lock);
942 		return;
943 	}
944 	atomic_set(&conn->connection_exit, 1);
945 
946 	if (conn->conn_state == TARG_CONN_STATE_IN_LOGOUT) {
947 		spin_unlock_bh(&conn->state_lock);
948 		iscsit_close_connection(conn);
949 		return;
950 	}
951 
952 	if (conn->conn_state == TARG_CONN_STATE_CLEANUP_WAIT) {
953 		spin_unlock_bh(&conn->state_lock);
954 		return;
955 	}
956 
957 	pr_debug("Moving to TARG_CONN_STATE_CLEANUP_WAIT.\n");
958 	conn->conn_state = TARG_CONN_STATE_CLEANUP_WAIT;
959 	spin_unlock_bh(&conn->state_lock);
960 
961 	iscsit_handle_connection_cleanup(conn);
962 }
963 
964 /*
965  *	This is the simple function that makes the magic of
966  *	sync and steering happen in the follow paradoxical order:
967  *
968  *	0) Receive conn->of_marker (bytes left until next OFMarker)
969  *	   bytes into an offload buffer.  When we pass the exact number
970  *	   of bytes in conn->of_marker, iscsit_dump_data_payload() and hence
971  *	   rx_data() will automatically receive the identical u32 marker
972  *	   values and store it in conn->of_marker_offset;
973  *	1) Now conn->of_marker_offset will contain the offset to the start
974  *	   of the next iSCSI PDU.  Dump these remaining bytes into another
975  *	   offload buffer.
976  *	2) We are done!
977  *	   Next byte in the TCP stream will contain the next iSCSI PDU!
978  *	   Cool Huh?!
979  */
980 int iscsit_recover_from_unknown_opcode(struct iscsi_conn *conn)
981 {
982 	/*
983 	 * Make sure the remaining bytes to next maker is a sane value.
984 	 */
985 	if (conn->of_marker > (conn->conn_ops->OFMarkInt * 4)) {
986 		pr_err("Remaining bytes to OFMarker: %u exceeds"
987 			" OFMarkInt bytes: %u.\n", conn->of_marker,
988 				conn->conn_ops->OFMarkInt * 4);
989 		return -1;
990 	}
991 
992 	pr_debug("Advancing %u bytes in TCP stream to get to the"
993 			" next OFMarker.\n", conn->of_marker);
994 
995 	if (iscsit_dump_data_payload(conn, conn->of_marker, 0) < 0)
996 		return -1;
997 
998 	/*
999 	 * Make sure the offset marker we retrived is a valid value.
1000 	 */
1001 	if (conn->of_marker_offset > (ISCSI_HDR_LEN + (ISCSI_CRC_LEN * 2) +
1002 	    conn->conn_ops->MaxRecvDataSegmentLength)) {
1003 		pr_err("OfMarker offset value: %u exceeds limit.\n",
1004 			conn->of_marker_offset);
1005 		return -1;
1006 	}
1007 
1008 	pr_debug("Discarding %u bytes of TCP stream to get to the"
1009 			" next iSCSI Opcode.\n", conn->of_marker_offset);
1010 
1011 	if (iscsit_dump_data_payload(conn, conn->of_marker_offset, 0) < 0)
1012 		return -1;
1013 
1014 	return 0;
1015 }
1016