drivers/target/iscsi/iscsi_target_tmr.c

   1 /*******************************************************************************
   2  * This file contains the iSCSI Target specific Task Management functions.
   3  *
   4  * (c) Copyright 2007-2013 Datera, Inc.
   5  *
   6  * Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  ******************************************************************************/
  18
  19 #include <asm/unaligned.h>
  20 #include <scsi/scsi_proto.h>
  21 #include <scsi/iscsi_proto.h>
  22 #include <target/target_core_base.h>
  23 #include <target/target_core_fabric.h>
  24 #include <target/iscsi/iscsi_transport.h>
  25
  26 #include <target/iscsi/iscsi_target_core.h>
  27 #include "iscsi_target_seq_pdu_list.h"
  28 #include "iscsi_target_datain_values.h"
  29 #include "iscsi_target_device.h"
  30 #include "iscsi_target_erl0.h"
  31 #include "iscsi_target_erl1.h"
  32 #include "iscsi_target_erl2.h"
  33 #include "iscsi_target_tmr.h"
  34 #include "iscsi_target_tpg.h"
  35 #include "iscsi_target_util.h"
  36 #include "iscsi_target.h"
  37
  38 u8 iscsit_tmr_abort_task(
  39         struct iscsi_cmd *cmd,
  40         unsigned char *buf)
  41 {
  42         struct iscsi_cmd *ref_cmd;
  43         struct iscsi_conn *conn = cmd->conn;
  44         struct iscsi_tmr_req *tmr_req = cmd->tmr_req;
  45         struct se_tmr_req *se_tmr = cmd->se_cmd.se_tmr_req;
  46         struct iscsi_tm *hdr = (struct iscsi_tm *) buf;
  47
  48         ref_cmd = iscsit_find_cmd_from_itt(conn, hdr->rtt);
  49         if (!ref_cmd) {
  50                 pr_err("Unable to locate RefTaskTag: 0x%08x on CID:"
  51                         " %hu.\n", hdr->rtt, conn->cid);
  52                 return (iscsi_sna_gte(be32_to_cpu(hdr->refcmdsn), conn->sess->exp_cmd_sn) &&
  53                         iscsi_sna_lte(be32_to_cpu(hdr->refcmdsn), conn->sess->max_cmd_sn)) ?
  54                         ISCSI_TMF_RSP_COMPLETE : ISCSI_TMF_RSP_NO_TASK;
  55         }
  56         if (ref_cmd->cmd_sn != be32_to_cpu(hdr->refcmdsn)) {
  57                 pr_err("RefCmdSN 0x%08x does not equal"
  58                         " task's CmdSN 0x%08x. Rejecting ABORT_TASK.\n",
  59                         hdr->refcmdsn, ref_cmd->cmd_sn);
  60                 return ISCSI_TMF_RSP_REJECTED;
  61         }
  62
  63         se_tmr->ref_task_tag            = (__force u32)hdr->rtt;
  64         tmr_req->ref_cmd                = ref_cmd;
  65         tmr_req->exp_data_sn            = be32_to_cpu(hdr->exp_datasn);
  66
  67         return ISCSI_TMF_RSP_COMPLETE;
  68 }
  69
  70 /*
  71  *      Called from iscsit_handle_task_mgt_cmd().
  72  */
  73 int iscsit_tmr_task_warm_reset(
  74         struct iscsi_conn *conn,
  75         struct iscsi_tmr_req *tmr_req,
  76         unsigned char *buf)
  77 {
  78         struct iscsi_session *sess = conn->sess;
  79         struct iscsi_node_attrib *na = iscsit_tpg_get_node_attrib(sess);
  80
  81         if (!na->tmr_warm_reset) {
  82                 pr_err("TMR Opcode TARGET_WARM_RESET authorization"
  83                         " failed for Initiator Node: %s\n",
  84                         sess->se_sess->se_node_acl->initiatorname);
  85                  return -1;
  86         }
  87         /*
  88          * Do the real work in transport_generic_do_tmr().
  89          */
  90         return 0;
  91 }
  92
  93 int iscsit_tmr_task_cold_reset(
  94         struct iscsi_conn *conn,
  95         struct iscsi_tmr_req *tmr_req,
  96         unsigned char *buf)
  97 {
  98         struct iscsi_session *sess = conn->sess;
  99         struct iscsi_node_attrib *na = iscsit_tpg_get_node_attrib(sess);
 100
 101         if (!na->tmr_cold_reset) {
 102                 pr_err("TMR Opcode TARGET_COLD_RESET authorization"
 103                         " failed for Initiator Node: %s\n",
 104                         sess->se_sess->se_node_acl->initiatorname);
 105                 return -1;
 106         }
 107         /*
 108          * Do the real work in transport_generic_do_tmr().
 109          */
 110         return 0;
 111 }
 112
 113 u8 iscsit_tmr_task_reassign(
 114         struct iscsi_cmd *cmd,
 115         unsigned char *buf)
 116 {
 117         struct iscsi_cmd *ref_cmd = NULL;
 118         struct iscsi_conn *conn = cmd->conn;
 119         struct iscsi_conn_recovery *cr = NULL;
 120         struct iscsi_tmr_req *tmr_req = cmd->tmr_req;
 121         struct se_tmr_req *se_tmr = cmd->se_cmd.se_tmr_req;
 122         struct iscsi_tm *hdr = (struct iscsi_tm *) buf;
 123         u64 ret, ref_lun;
 124
 125         pr_debug("Got TASK_REASSIGN TMR ITT: 0x%08x,"
 126                 " RefTaskTag: 0x%08x, ExpDataSN: 0x%08x, CID: %hu\n",
 127                 hdr->itt, hdr->rtt, hdr->exp_datasn, conn->cid);
 128
 129         if (conn->sess->sess_ops->ErrorRecoveryLevel != 2) {
 130                 pr_err("TMR TASK_REASSIGN not supported in ERL<2,"
 131                                 " ignoring request.\n");
 132                 return ISCSI_TMF_RSP_NOT_SUPPORTED;
 133         }
 134
 135         ret = iscsit_find_cmd_for_recovery(conn->sess, &ref_cmd, &cr, hdr->rtt);
 136         if (ret == -2) {
 137                 pr_err("Command ITT: 0x%08x is still alligent to CID:"
 138                         " %hu\n", ref_cmd->init_task_tag, cr->cid);
 139                 return ISCSI_TMF_RSP_TASK_ALLEGIANT;
 140         } else if (ret == -1) {
 141                 pr_err("Unable to locate RefTaskTag: 0x%08x in"
 142                         " connection recovery command list.\n", hdr->rtt);
 143                 return ISCSI_TMF_RSP_NO_TASK;
 144         }
 145         /*
 146          * Temporary check to prevent connection recovery for
 147          * connections with a differing Max*DataSegmentLength.
 148          */
 149         if (cr->maxrecvdatasegmentlength !=
 150             conn->conn_ops->MaxRecvDataSegmentLength) {
 151                 pr_err("Unable to perform connection recovery for"
 152                         " differing MaxRecvDataSegmentLength, rejecting"
 153                         " TMR TASK_REASSIGN.\n");
 154                 return ISCSI_TMF_RSP_REJECTED;
 155         }
 156         if (cr->maxxmitdatasegmentlength !=
 157             conn->conn_ops->MaxXmitDataSegmentLength) {
 158                 pr_err("Unable to perform connection recovery for"
 159                         " differing MaxXmitDataSegmentLength, rejecting"
 160                         " TMR TASK_REASSIGN.\n");
 161                 return ISCSI_TMF_RSP_REJECTED;
 162         }
 163
 164         ref_lun = scsilun_to_int(&hdr->lun);
 165         if (ref_lun != ref_cmd->se_cmd.orig_fe_lun) {
 166                 pr_err("Unable to perform connection recovery for"
 167                         " differing ref_lun: %llu ref_cmd orig_fe_lun: %llu\n",
 168                         ref_lun, ref_cmd->se_cmd.orig_fe_lun);
 169                 return ISCSI_TMF_RSP_REJECTED;
 170         }
 171
 172         se_tmr->ref_task_tag            = (__force u32)hdr->rtt;
 173         tmr_req->ref_cmd                = ref_cmd;
 174         tmr_req->exp_data_sn            = be32_to_cpu(hdr->exp_datasn);
 175         tmr_req->conn_recovery          = cr;
 176         tmr_req->task_reassign          = 1;
 177         /*
 178          * Command can now be reassigned to a new connection.
 179          * The task management response must be sent before the
 180          * reassignment actually happens.  See iscsi_tmr_post_handler().
 181          */
 182         return ISCSI_TMF_RSP_COMPLETE;
 183 }
 184
 185 static void iscsit_task_reassign_remove_cmd(
 186         struct iscsi_cmd *cmd,
 187         struct iscsi_conn_recovery *cr,
 188         struct iscsi_session *sess)
 189 {
 190         int ret;
 191
 192         spin_lock(&cr->conn_recovery_cmd_lock);
 193         ret = iscsit_remove_cmd_from_connection_recovery(cmd, sess);
 194         spin_unlock(&cr->conn_recovery_cmd_lock);
 195         if (!ret) {
 196                 pr_debug("iSCSI connection recovery successful for CID:"
 197                         " %hu on SID: %u\n", cr->cid, sess->sid);
 198                 iscsit_remove_active_connection_recovery_entry(cr, sess);
 199         }
 200 }
 201
 202 static int iscsit_task_reassign_complete_nop_out(
 203         struct iscsi_tmr_req *tmr_req,
 204         struct iscsi_conn *conn)
 205 {
 206         struct iscsi_cmd *cmd = tmr_req->ref_cmd;
 207         struct iscsi_conn_recovery *cr;
 208
 209         if (!cmd->cr) {
 210                 pr_err("struct iscsi_conn_recovery pointer for ITT: 0x%08x"
 211                         " is NULL!\n", cmd->init_task_tag);
 212                 return -1;
 213         }
 214         cr = cmd->cr;
 215
 216         /*
 217          * Reset the StatSN so a new one for this commands new connection
 218          * will be assigned.
 219          * Reset the ExpStatSN as well so we may receive Status SNACKs.
 220          */
 221         cmd->stat_sn = cmd->exp_stat_sn = 0;
 222
 223         iscsit_task_reassign_remove_cmd(cmd, cr, conn->sess);
 224
 225         spin_lock_bh(&conn->cmd_lock);
 226         list_add_tail(&cmd->i_conn_node, &conn->conn_cmd_list);
 227         spin_unlock_bh(&conn->cmd_lock);
 228
 229         cmd->i_state = ISTATE_SEND_NOPIN;
 230         iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
 231         return 0;
 232 }
 233
 234 static int iscsit_task_reassign_complete_write(
 235         struct iscsi_cmd *cmd,
 236         struct iscsi_tmr_req *tmr_req)
 237 {
 238         int no_build_r2ts = 0;
 239         u32 length = 0, offset = 0;
 240         struct iscsi_conn *conn = cmd->conn;
 241         struct se_cmd *se_cmd = &cmd->se_cmd;
 242         /*
 243          * The Initiator must not send a R2T SNACK with a Begrun less than
 244          * the TMR TASK_REASSIGN's ExpDataSN.
 245          */
 246         if (!tmr_req->exp_data_sn) {
 247                 cmd->cmd_flags &= ~ICF_GOT_DATACK_SNACK;
 248                 cmd->acked_data_sn = 0;
 249         } else {
 250                 cmd->cmd_flags |= ICF_GOT_DATACK_SNACK;
 251                 cmd->acked_data_sn = (tmr_req->exp_data_sn - 1);
 252         }
 253
 254         /*
 255          * The TMR TASK_REASSIGN's ExpDataSN contains the next R2TSN the
 256          * Initiator is expecting.  The Target controls all WRITE operations
 257          * so if we have received all DataOUT we can safety ignore Initiator.
 258          */
 259         if (cmd->cmd_flags & ICF_GOT_LAST_DATAOUT) {
 260                 if (!(cmd->se_cmd.transport_state & CMD_T_SENT)) {
 261                         pr_debug("WRITE ITT: 0x%08x: t_state: %d"
 262                                 " never sent to transport\n",
 263                                 cmd->init_task_tag, cmd->se_cmd.t_state);
 264                         target_execute_cmd(se_cmd);
 265                         return 0;
 266                 }
 267
 268                 cmd->i_state = ISTATE_SEND_STATUS;
 269                 iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
 270                 return 0;
 271         }
 272
 273         /*
 274          * Special case to deal with DataSequenceInOrder=No and Non-Immeidate
 275          * Unsolicited DataOut.
 276          */
 277         if (cmd->unsolicited_data) {
 278                 cmd->unsolicited_data = 0;
 279
 280                 offset = cmd->next_burst_len = cmd->write_data_done;
 281
 282                 if ((conn->sess->sess_ops->FirstBurstLength - offset) >=
 283                      cmd->se_cmd.data_length) {
 284                         no_build_r2ts = 1;
 285                         length = (cmd->se_cmd.data_length - offset);
 286                 } else
 287                         length = (conn->sess->sess_ops->FirstBurstLength - offset);
 288
 289                 spin_lock_bh(&cmd->r2t_lock);
 290                 if (iscsit_add_r2t_to_list(cmd, offset, length, 0, 0) < 0) {
 291                         spin_unlock_bh(&cmd->r2t_lock);
 292                         return -1;
 293                 }
 294                 cmd->outstanding_r2ts++;
 295                 spin_unlock_bh(&cmd->r2t_lock);
 296
 297                 if (no_build_r2ts)
 298                         return 0;
 299         }
 300         /*
 301          * iscsit_build_r2ts_for_cmd() can handle the rest from here.
 302          */
 303         return conn->conn_transport->iscsit_get_dataout(conn, cmd, true);
 304 }
 305
 306 static int iscsit_task_reassign_complete_read(
 307         struct iscsi_cmd *cmd,
 308         struct iscsi_tmr_req *tmr_req)
 309 {
 310         struct iscsi_conn *conn = cmd->conn;
 311         struct iscsi_datain_req *dr;
 312         struct se_cmd *se_cmd = &cmd->se_cmd;
 313         /*
 314          * The Initiator must not send a Data SNACK with a BegRun less than
 315          * the TMR TASK_REASSIGN's ExpDataSN.
 316          */
 317         if (!tmr_req->exp_data_sn) {
 318                 cmd->cmd_flags &= ~ICF_GOT_DATACK_SNACK;
 319                 cmd->acked_data_sn = 0;
 320         } else {
 321                 cmd->cmd_flags |= ICF_GOT_DATACK_SNACK;
 322                 cmd->acked_data_sn = (tmr_req->exp_data_sn - 1);
 323         }
 324
 325         if (!(cmd->se_cmd.transport_state & CMD_T_SENT)) {
 326                 pr_debug("READ ITT: 0x%08x: t_state: %d never sent to"
 327                         " transport\n", cmd->init_task_tag,
 328                         cmd->se_cmd.t_state);
 329                 transport_handle_cdb_direct(se_cmd);
 330                 return 0;
 331         }
 332
 333         if (!(se_cmd->transport_state & CMD_T_COMPLETE)) {
 334                 pr_err("READ ITT: 0x%08x: t_state: %d, never returned"
 335                         " from transport\n", cmd->init_task_tag,
 336                         cmd->se_cmd.t_state);
 337                 return -1;
 338         }
 339
 340         dr = iscsit_allocate_datain_req();
 341         if (!dr)
 342                 return -1;
 343         /*
 344          * The TMR TASK_REASSIGN's ExpDataSN contains the next DataSN the
 345          * Initiator is expecting.
 346          */
 347         dr->data_sn = dr->begrun = tmr_req->exp_data_sn;
 348         dr->runlength = 0;
 349         dr->generate_recovery_values = 1;
 350         dr->recovery = DATAIN_CONNECTION_RECOVERY;
 351
 352         iscsit_attach_datain_req(cmd, dr);
 353
 354         cmd->i_state = ISTATE_SEND_DATAIN;
 355         iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
 356         return 0;
 357 }
 358
 359 static int iscsit_task_reassign_complete_none(
 360         struct iscsi_cmd *cmd,
 361         struct iscsi_tmr_req *tmr_req)
 362 {
 363         struct iscsi_conn *conn = cmd->conn;
 364
 365         cmd->i_state = ISTATE_SEND_STATUS;
 366         iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
 367         return 0;
 368 }
 369
 370 static int iscsit_task_reassign_complete_scsi_cmnd(
 371         struct iscsi_tmr_req *tmr_req,
 372         struct iscsi_conn *conn)
 373 {
 374         struct iscsi_cmd *cmd = tmr_req->ref_cmd;
 375         struct iscsi_conn_recovery *cr;
 376
 377         if (!cmd->cr) {
 378                 pr_err("struct iscsi_conn_recovery pointer for ITT: 0x%08x"
 379                         " is NULL!\n", cmd->init_task_tag);
 380                 return -1;
 381         }
 382         cr = cmd->cr;
 383
 384         /*
 385          * Reset the StatSN so a new one for this commands new connection
 386          * will be assigned.
 387          * Reset the ExpStatSN as well so we may receive Status SNACKs.
 388          */
 389         cmd->stat_sn = cmd->exp_stat_sn = 0;
 390
 391         iscsit_task_reassign_remove_cmd(cmd, cr, conn->sess);
 392
 393         spin_lock_bh(&conn->cmd_lock);
 394         list_add_tail(&cmd->i_conn_node, &conn->conn_cmd_list);
 395         spin_unlock_bh(&conn->cmd_lock);
 396
 397         if (cmd->se_cmd.se_cmd_flags & SCF_SENT_CHECK_CONDITION) {
 398                 cmd->i_state = ISTATE_SEND_STATUS;
 399                 iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
 400                 return 0;
 401         }
 402
 403         switch (cmd->data_direction) {
 404         case DMA_TO_DEVICE:
 405                 return iscsit_task_reassign_complete_write(cmd, tmr_req);
 406         case DMA_FROM_DEVICE:
 407                 return iscsit_task_reassign_complete_read(cmd, tmr_req);
 408         case DMA_NONE:
 409                 return iscsit_task_reassign_complete_none(cmd, tmr_req);
 410         default:
 411                 pr_err("Unknown cmd->data_direction: 0x%02x\n",
 412                                 cmd->data_direction);
 413                 return -1;
 414         }
 415
 416         return 0;
 417 }
 418
 419 static int iscsit_task_reassign_complete(
 420         struct iscsi_tmr_req *tmr_req,
 421         struct iscsi_conn *conn)
 422 {
 423         struct iscsi_cmd *cmd;
 424         int ret = 0;
 425
 426         if (!tmr_req->ref_cmd) {
 427                 pr_err("TMR Request is missing a RefCmd struct iscsi_cmd.\n");
 428                 return -1;
 429         }
 430         cmd = tmr_req->ref_cmd;
 431
 432         cmd->conn = conn;
 433
 434         switch (cmd->iscsi_opcode) {
 435         case ISCSI_OP_NOOP_OUT:
 436                 ret = iscsit_task_reassign_complete_nop_out(tmr_req, conn);
 437                 break;
 438         case ISCSI_OP_SCSI_CMD:
 439                 ret = iscsit_task_reassign_complete_scsi_cmnd(tmr_req, conn);
 440                 break;
 441         default:
 442                  pr_err("Illegal iSCSI Opcode 0x%02x during"
 443                         " command realligence\n", cmd->iscsi_opcode);
 444                 return -1;
 445         }
 446
 447         if (ret != 0)
 448                 return ret;
 449
 450         pr_debug("Completed connection realligence for Opcode: 0x%02x,"
 451                 " ITT: 0x%08x to CID: %hu.\n", cmd->iscsi_opcode,
 452                         cmd->init_task_tag, conn->cid);
 453
 454         return 0;
 455 }
 456
 457 /*
 458  *      Handles special after-the-fact actions related to TMRs.
 459  *      Right now the only one that its really needed for is
 460  *      connection recovery releated TASK_REASSIGN.
 461  */
 462 int iscsit_tmr_post_handler(struct iscsi_cmd *cmd, struct iscsi_conn *conn)
 463 {
 464         struct iscsi_tmr_req *tmr_req = cmd->tmr_req;
 465         struct se_tmr_req *se_tmr = cmd->se_cmd.se_tmr_req;
 466
 467         if (tmr_req->task_reassign &&
 468            (se_tmr->response == ISCSI_TMF_RSP_COMPLETE))
 469                 return iscsit_task_reassign_complete(tmr_req, conn);
 470
 471         return 0;
 472 }
 473 EXPORT_SYMBOL(iscsit_tmr_post_handler);
 474
 475 /*
 476  *      Nothing to do here, but leave it for good measure. :-)
 477  */
 478 static int iscsit_task_reassign_prepare_read(
 479         struct iscsi_tmr_req *tmr_req,
 480         struct iscsi_conn *conn)
 481 {
 482         return 0;
 483 }
 484
 485 static void iscsit_task_reassign_prepare_unsolicited_dataout(
 486         struct iscsi_cmd *cmd,
 487         struct iscsi_conn *conn)
 488 {
 489         int i, j;
 490         struct iscsi_pdu *pdu = NULL;
 491         struct iscsi_seq *seq = NULL;
 492
 493         if (conn->sess->sess_ops->DataSequenceInOrder) {
 494                 cmd->data_sn = 0;
 495
 496                 if (cmd->immediate_data)
 497                         cmd->r2t_offset += (cmd->first_burst_len -
 498                                 cmd->seq_start_offset);
 499
 500                 if (conn->sess->sess_ops->DataPDUInOrder) {
 501                         cmd->write_data_done -= (cmd->immediate_data) ?
 502                                                 (cmd->first_burst_len -
 503                                                  cmd->seq_start_offset) :
 504                                                  cmd->first_burst_len;
 505                         cmd->first_burst_len = 0;
 506                         return;
 507                 }
 508
 509                 for (i = 0; i < cmd->pdu_count; i++) {
 510                         pdu = &cmd->pdu_list[i];
 511
 512                         if (pdu->status != ISCSI_PDU_RECEIVED_OK)
 513                                 continue;
 514
 515                         if ((pdu->offset >= cmd->seq_start_offset) &&
 516                            ((pdu->offset + pdu->length) <=
 517                              cmd->seq_end_offset)) {
 518                                 cmd->first_burst_len -= pdu->length;
 519                                 cmd->write_data_done -= pdu->length;
 520                                 pdu->status = ISCSI_PDU_NOT_RECEIVED;
 521                         }
 522                 }
 523         } else {
 524                 for (i = 0; i < cmd->seq_count; i++) {
 525                         seq = &cmd->seq_list[i];
 526
 527                         if (seq->type != SEQTYPE_UNSOLICITED)
 528                                 continue;
 529
 530                         cmd->write_data_done -=
 531                                         (seq->offset - seq->orig_offset);
 532                         cmd->first_burst_len = 0;
 533                         seq->data_sn = 0;
 534                         seq->offset = seq->orig_offset;
 535                         seq->next_burst_len = 0;
 536                         seq->status = DATAOUT_SEQUENCE_WITHIN_COMMAND_RECOVERY;
 537
 538                         if (conn->sess->sess_ops->DataPDUInOrder)
 539                                 continue;
 540
 541                         for (j = 0; j < seq->pdu_count; j++) {
 542                                 pdu = &cmd->pdu_list[j+seq->pdu_start];
 543
 544                                 if (pdu->status != ISCSI_PDU_RECEIVED_OK)
 545                                         continue;
 546
 547                                 pdu->status = ISCSI_PDU_NOT_RECEIVED;
 548                         }
 549                 }
 550         }
 551 }
 552
 553 static int iscsit_task_reassign_prepare_write(
 554         struct iscsi_tmr_req *tmr_req,
 555         struct iscsi_conn *conn)
 556 {
 557         struct iscsi_cmd *cmd = tmr_req->ref_cmd;
 558         struct iscsi_pdu *pdu = NULL;
 559         struct iscsi_r2t *r2t = NULL, *r2t_tmp;
 560         int first_incomplete_r2t = 1, i = 0;
 561
 562         /*
 563          * The command was in the process of receiving Unsolicited DataOUT when
 564          * the connection failed.
 565          */
 566         if (cmd->unsolicited_data)
 567                 iscsit_task_reassign_prepare_unsolicited_dataout(cmd, conn);
 568
 569         /*
 570          * The Initiator is requesting R2Ts starting from zero,  skip
 571          * checking acknowledged R2Ts and start checking struct iscsi_r2ts
 572          * greater than zero.
 573          */
 574         if (!tmr_req->exp_data_sn)
 575                 goto drop_unacknowledged_r2ts;
 576
 577         /*
 578          * We now check that the PDUs in DataOUT sequences below
 579          * the TMR TASK_REASSIGN ExpDataSN (R2TSN the Initiator is
 580          * expecting next) have all the DataOUT they require to complete
 581          * the DataOUT sequence.  First scan from R2TSN 0 to TMR
 582          * TASK_REASSIGN ExpDataSN-1.
 583          *
 584          * If we have not received all DataOUT in question,  we must
 585          * make sure to make the appropriate changes to values in
 586          * struct iscsi_cmd (and elsewhere depending on session parameters)
 587          * so iscsit_build_r2ts_for_cmd() in iscsit_task_reassign_complete_write()
 588          * will resend a new R2T for the DataOUT sequences in question.
 589          */
 590         spin_lock_bh(&cmd->r2t_lock);
 591         if (list_empty(&cmd->cmd_r2t_list)) {
 592                 spin_unlock_bh(&cmd->r2t_lock);
 593                 return -1;
 594         }
 595
 596         list_for_each_entry(r2t, &cmd->cmd_r2t_list, r2t_list) {
 597
 598                 if (r2t->r2t_sn >= tmr_req->exp_data_sn)
 599                         continue;
 600                 /*
 601                  * Safely ignore Recovery R2Ts and R2Ts that have completed
 602                  * DataOUT sequences.
 603                  */
 604                 if (r2t->seq_complete)
 605                         continue;
 606
 607                 if (r2t->recovery_r2t)
 608                         continue;
 609
 610                 /*
 611                  *                 DataSequenceInOrder=Yes:
 612                  *
 613                  * Taking into account the iSCSI implementation requirement of
 614                  * MaxOutstandingR2T=1 while ErrorRecoveryLevel>0 and
 615                  * DataSequenceInOrder=Yes, we must take into consideration
 616                  * the following:
 617                  *
 618                  *                  DataSequenceInOrder=No:
 619                  *
 620                  * Taking into account that the Initiator controls the (possibly
 621                  * random) PDU Order in (possibly random) Sequence Order of
 622                  * DataOUT the target requests with R2Ts,  we must take into
 623                  * consideration the following:
 624                  *
 625                  *      DataPDUInOrder=Yes for DataSequenceInOrder=[Yes,No]:
 626                  *
 627                  * While processing non-complete R2T DataOUT sequence requests
 628                  * the Target will re-request only the total sequence length
 629                  * minus current received offset.  This is because we must
 630                  * assume the initiator will continue sending DataOUT from the
 631                  * last PDU before the connection failed.
 632                  *
 633                  *      DataPDUInOrder=No for DataSequenceInOrder=[Yes,No]:
 634                  *
 635                  * While processing non-complete R2T DataOUT sequence requests
 636                  * the Target will re-request the entire DataOUT sequence if
 637                  * any single PDU is missing from the sequence.  This is because
 638                  * we have no logical method to determine the next PDU offset,
 639                  * and we must assume the Initiator will be sending any random
 640                  * PDU offset in the current sequence after TASK_REASSIGN
 641                  * has completed.
 642                  */
 643                 if (conn->sess->sess_ops->DataSequenceInOrder) {
 644                         if (!first_incomplete_r2t) {
 645                                 cmd->r2t_offset -= r2t->xfer_len;
 646                                 goto next;
 647                         }
 648
 649                         if (conn->sess->sess_ops->DataPDUInOrder) {
 650                                 cmd->data_sn = 0;
 651                                 cmd->r2t_offset -= (r2t->xfer_len -
 652                                         cmd->next_burst_len);
 653                                 first_incomplete_r2t = 0;
 654                                 goto next;
 655                         }
 656
 657                         cmd->data_sn = 0;
 658                         cmd->r2t_offset -= r2t->xfer_len;
 659
 660                         for (i = 0; i < cmd->pdu_count; i++) {
 661                                 pdu = &cmd->pdu_list[i];
 662
 663                                 if (pdu->status != ISCSI_PDU_RECEIVED_OK)
 664                                         continue;
 665
 666                                 if ((pdu->offset >= r2t->offset) &&
 667                                     (pdu->offset < (r2t->offset +
 668                                                 r2t->xfer_len))) {
 669                                         cmd->next_burst_len -= pdu->length;
 670                                         cmd->write_data_done -= pdu->length;
 671                                         pdu->status = ISCSI_PDU_NOT_RECEIVED;
 672                                 }
 673                         }
 674
 675                         first_incomplete_r2t = 0;
 676                 } else {
 677                         struct iscsi_seq *seq;
 678
 679                         seq = iscsit_get_seq_holder(cmd, r2t->offset,
 680                                         r2t->xfer_len);
 681                         if (!seq) {
 682                                 spin_unlock_bh(&cmd->r2t_lock);
 683                                 return -1;
 684                         }
 685
 686                         cmd->write_data_done -=
 687                                         (seq->offset - seq->orig_offset);
 688                         seq->data_sn = 0;
 689                         seq->offset = seq->orig_offset;
 690                         seq->next_burst_len = 0;
 691                         seq->status = DATAOUT_SEQUENCE_WITHIN_COMMAND_RECOVERY;
 692
 693                         cmd->seq_send_order--;
 694
 695                         if (conn->sess->sess_ops->DataPDUInOrder)
 696                                 goto next;
 697
 698                         for (i = 0; i < seq->pdu_count; i++) {
 699                                 pdu = &cmd->pdu_list[i+seq->pdu_start];
 700
 701                                 if (pdu->status != ISCSI_PDU_RECEIVED_OK)
 702                                         continue;
 703
 704                                 pdu->status = ISCSI_PDU_NOT_RECEIVED;
 705                         }
 706                 }
 707
 708 next:
 709                 cmd->outstanding_r2ts--;
 710         }
 711         spin_unlock_bh(&cmd->r2t_lock);
 712
 713         /*
 714          * We now drop all unacknowledged R2Ts, ie: ExpDataSN from TMR
 715          * TASK_REASSIGN to the last R2T in the list..  We are also careful
 716          * to check that the Initiator is not requesting R2Ts for DataOUT
 717          * sequences it has already completed.
 718          *
 719          * Free each R2T in question and adjust values in struct iscsi_cmd
 720          * accordingly so iscsit_build_r2ts_for_cmd() do the rest of
 721          * the work after the TMR TASK_REASSIGN Response is sent.
 722          */
 723 drop_unacknowledged_r2ts:
 724
 725         cmd->cmd_flags &= ~ICF_SENT_LAST_R2T;
 726         cmd->r2t_sn = tmr_req->exp_data_sn;
 727
 728         spin_lock_bh(&cmd->r2t_lock);
 729         list_for_each_entry_safe(r2t, r2t_tmp, &cmd->cmd_r2t_list, r2t_list) {
 730                 /*
 731                  * Skip up to the R2T Sequence number provided by the
 732                  * iSCSI TASK_REASSIGN TMR
 733                  */
 734                 if (r2t->r2t_sn < tmr_req->exp_data_sn)
 735                         continue;
 736
 737                 if (r2t->seq_complete) {
 738                         pr_err("Initiator is requesting R2Ts from"
 739                                 " R2TSN: 0x%08x, but R2TSN: 0x%08x, Offset: %u,"
 740                                 " Length: %u is already complete."
 741                                 "   BAD INITIATOR ERL=2 IMPLEMENTATION!\n",
 742                                 tmr_req->exp_data_sn, r2t->r2t_sn,
 743                                 r2t->offset, r2t->xfer_len);
 744                         spin_unlock_bh(&cmd->r2t_lock);
 745                         return -1;
 746                 }
 747
 748                 if (r2t->recovery_r2t) {
 749                         iscsit_free_r2t(r2t, cmd);
 750                         continue;
 751                 }
 752
 753                 /*                 DataSequenceInOrder=Yes:
 754                  *
 755                  * Taking into account the iSCSI implementation requirement of
 756                  * MaxOutstandingR2T=1 while ErrorRecoveryLevel>0 and
 757                  * DataSequenceInOrder=Yes, it's safe to subtract the R2Ts
 758                  * entire transfer length from the commands R2T offset marker.
 759                  *
 760                  *                 DataSequenceInOrder=No:
 761                  *
 762                  * We subtract the difference from struct iscsi_seq between the
 763                  * current offset and original offset from cmd->write_data_done
 764                  * for account for DataOUT PDUs already received.  Then reset
 765                  * the current offset to the original and zero out the current
 766                  * burst length,  to make sure we re-request the entire DataOUT
 767                  * sequence.
 768                  */
 769                 if (conn->sess->sess_ops->DataSequenceInOrder)
 770                         cmd->r2t_offset -= r2t->xfer_len;
 771                 else
 772                         cmd->seq_send_order--;
 773
 774                 cmd->outstanding_r2ts--;
 775                 iscsit_free_r2t(r2t, cmd);
 776         }
 777         spin_unlock_bh(&cmd->r2t_lock);
 778
 779         return 0;
 780 }
 781
 782 /*
 783  *      Performs sanity checks TMR TASK_REASSIGN's ExpDataSN for
 784  *      a given struct iscsi_cmd.
 785  */
 786 int iscsit_check_task_reassign_expdatasn(
 787         struct iscsi_tmr_req *tmr_req,
 788         struct iscsi_conn *conn)
 789 {
 790         struct iscsi_cmd *ref_cmd = tmr_req->ref_cmd;
 791
 792         if (ref_cmd->iscsi_opcode != ISCSI_OP_SCSI_CMD)
 793                 return 0;
 794
 795         if (ref_cmd->se_cmd.se_cmd_flags & SCF_SENT_CHECK_CONDITION)
 796                 return 0;
 797
 798         if (ref_cmd->data_direction == DMA_NONE)
 799                 return 0;
 800
 801         /*
 802          * For READs the TMR TASK_REASSIGNs ExpDataSN contains the next DataSN
 803          * of DataIN the Initiator is expecting.
 804          *
 805          * Also check that the Initiator is not re-requesting DataIN that has
 806          * already been acknowledged with a DataAck SNACK.
 807          */
 808         if (ref_cmd->data_direction == DMA_FROM_DEVICE) {
 809                 if (tmr_req->exp_data_sn > ref_cmd->data_sn) {
 810                         pr_err("Received ExpDataSN: 0x%08x for READ"
 811                                 " in TMR TASK_REASSIGN greater than command's"
 812                                 " DataSN: 0x%08x.\n", tmr_req->exp_data_sn,
 813                                 ref_cmd->data_sn);
 814                         return -1;
 815                 }
 816                 if ((ref_cmd->cmd_flags & ICF_GOT_DATACK_SNACK) &&
 817                     (tmr_req->exp_data_sn <= ref_cmd->acked_data_sn)) {
 818                         pr_err("Received ExpDataSN: 0x%08x for READ"
 819                                 " in TMR TASK_REASSIGN for previously"
 820                                 " acknowledged DataIN: 0x%08x,"
 821                                 " protocol error\n", tmr_req->exp_data_sn,
 822                                 ref_cmd->acked_data_sn);
 823                         return -1;
 824                 }
 825                 return iscsit_task_reassign_prepare_read(tmr_req, conn);
 826         }
 827
 828         /*
 829          * For WRITEs the TMR TASK_REASSIGNs ExpDataSN contains the next R2TSN
 830          * for R2Ts the Initiator is expecting.
 831          *
 832          * Do the magic in iscsit_task_reassign_prepare_write().
 833          */
 834         if (ref_cmd->data_direction == DMA_TO_DEVICE) {
 835                 if (tmr_req->exp_data_sn > ref_cmd->r2t_sn) {
 836                         pr_err("Received ExpDataSN: 0x%08x for WRITE"
 837                                 " in TMR TASK_REASSIGN greater than command's"
 838                                 " R2TSN: 0x%08x.\n", tmr_req->exp_data_sn,
 839                                         ref_cmd->r2t_sn);
 840                         return -1;
 841                 }
 842                 return iscsit_task_reassign_prepare_write(tmr_req, conn);
 843         }
 844
 845         pr_err("Unknown iSCSI data_direction: 0x%02x\n",
 846                         ref_cmd->data_direction);
 847
 848         return -1;
 849 }