drivers/target/iscsi/iscsi_target_tmr.c

   1 /*******************************************************************************
   2  * This file contains the iSCSI Target specific Task Management functions.
   3  *
   4  * \u00a9 Copyright 2007-2011 RisingTide Systems LLC.
   5  *
   6  * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
   7  *
   8  * Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  ******************************************************************************/
  20
  21 #include <asm/unaligned.h>
  22 #include <scsi/scsi_device.h>
  23 #include <scsi/iscsi_proto.h>
  24 #include <target/target_core_base.h>
  25 #include <target/target_core_fabric.h>
  26 #include <target/iscsi/iscsi_transport.h>
  27
  28 #include "iscsi_target_core.h"
  29 #include "iscsi_target_seq_pdu_list.h"
  30 #include "iscsi_target_datain_values.h"
  31 #include "iscsi_target_device.h"
  32 #include "iscsi_target_erl0.h"
  33 #include "iscsi_target_erl1.h"
  34 #include "iscsi_target_erl2.h"
  35 #include "iscsi_target_tmr.h"
  36 #include "iscsi_target_tpg.h"
  37 #include "iscsi_target_util.h"
  38 #include "iscsi_target.h"
  39
  40 u8 iscsit_tmr_abort_task(
  41         struct iscsi_cmd *cmd,
  42         unsigned char *buf)
  43 {
  44         struct iscsi_cmd *ref_cmd;
  45         struct iscsi_conn *conn = cmd->conn;
  46         struct iscsi_tmr_req *tmr_req = cmd->tmr_req;
  47         struct se_tmr_req *se_tmr = cmd->se_cmd.se_tmr_req;
  48         struct iscsi_tm *hdr = (struct iscsi_tm *) buf;
  49
  50         ref_cmd = iscsit_find_cmd_from_itt(conn, hdr->rtt);
  51         if (!ref_cmd) {
  52                 pr_err("Unable to locate RefTaskTag: 0x%08x on CID:"
  53                         " %hu.\n", hdr->rtt, conn->cid);
  54                 return (iscsi_sna_gte(be32_to_cpu(hdr->refcmdsn), conn->sess->exp_cmd_sn) &&
  55                         iscsi_sna_lte(be32_to_cpu(hdr->refcmdsn), conn->sess->max_cmd_sn)) ?
  56                         ISCSI_TMF_RSP_COMPLETE : ISCSI_TMF_RSP_NO_TASK;
  57         }
  58         if (ref_cmd->cmd_sn != be32_to_cpu(hdr->refcmdsn)) {
  59                 pr_err("RefCmdSN 0x%08x does not equal"
  60                         " task's CmdSN 0x%08x. Rejecting ABORT_TASK.\n",
  61                         hdr->refcmdsn, ref_cmd->cmd_sn);
  62                 return ISCSI_TMF_RSP_REJECTED;
  63         }
  64
  65         se_tmr->ref_task_tag            = (__force u32)hdr->rtt;
  66         tmr_req->ref_cmd                = ref_cmd;
  67         tmr_req->exp_data_sn            = be32_to_cpu(hdr->exp_datasn);
  68
  69         return ISCSI_TMF_RSP_COMPLETE;
  70 }
  71
  72 /*
  73  *      Called from iscsit_handle_task_mgt_cmd().
  74  */
  75 int iscsit_tmr_task_warm_reset(
  76         struct iscsi_conn *conn,
  77         struct iscsi_tmr_req *tmr_req,
  78         unsigned char *buf)
  79 {
  80         struct iscsi_session *sess = conn->sess;
  81         struct iscsi_node_attrib *na = iscsit_tpg_get_node_attrib(sess);
  82
  83         if (!na->tmr_warm_reset) {
  84                 pr_err("TMR Opcode TARGET_WARM_RESET authorization"
  85                         " failed for Initiator Node: %s\n",
  86                         sess->se_sess->se_node_acl->initiatorname);
  87                  return -1;
  88         }
  89         /*
  90          * Do the real work in transport_generic_do_tmr().
  91          */
  92         return 0;
  93 }
  94
  95 int iscsit_tmr_task_cold_reset(
  96         struct iscsi_conn *conn,
  97         struct iscsi_tmr_req *tmr_req,
  98         unsigned char *buf)
  99 {
 100         struct iscsi_session *sess = conn->sess;
 101         struct iscsi_node_attrib *na = iscsit_tpg_get_node_attrib(sess);
 102
 103         if (!na->tmr_cold_reset) {
 104                 pr_err("TMR Opcode TARGET_COLD_RESET authorization"
 105                         " failed for Initiator Node: %s\n",
 106                         sess->se_sess->se_node_acl->initiatorname);
 107                 return -1;
 108         }
 109         /*
 110          * Do the real work in transport_generic_do_tmr().
 111          */
 112         return 0;
 113 }
 114
 115 u8 iscsit_tmr_task_reassign(
 116         struct iscsi_cmd *cmd,
 117         unsigned char *buf)
 118 {
 119         struct iscsi_cmd *ref_cmd = NULL;
 120         struct iscsi_conn *conn = cmd->conn;
 121         struct iscsi_conn_recovery *cr = NULL;
 122         struct iscsi_tmr_req *tmr_req = cmd->tmr_req;
 123         struct se_tmr_req *se_tmr = cmd->se_cmd.se_tmr_req;
 124         struct iscsi_tm *hdr = (struct iscsi_tm *) buf;
 125         int ret, ref_lun;
 126
 127         pr_debug("Got TASK_REASSIGN TMR ITT: 0x%08x,"
 128                 " RefTaskTag: 0x%08x, ExpDataSN: 0x%08x, CID: %hu\n",
 129                 hdr->itt, hdr->rtt, hdr->exp_datasn, conn->cid);
 130
 131         if (conn->sess->sess_ops->ErrorRecoveryLevel != 2) {
 132                 pr_err("TMR TASK_REASSIGN not supported in ERL<2,"
 133                                 " ignoring request.\n");
 134                 return ISCSI_TMF_RSP_NOT_SUPPORTED;
 135         }
 136
 137         ret = iscsit_find_cmd_for_recovery(conn->sess, &ref_cmd, &cr, hdr->rtt);
 138         if (ret == -2) {
 139                 pr_err("Command ITT: 0x%08x is still alligent to CID:"
 140                         " %hu\n", ref_cmd->init_task_tag, cr->cid);
 141                 return ISCSI_TMF_RSP_TASK_ALLEGIANT;
 142         } else if (ret == -1) {
 143                 pr_err("Unable to locate RefTaskTag: 0x%08x in"
 144                         " connection recovery command list.\n", hdr->rtt);
 145                 return ISCSI_TMF_RSP_NO_TASK;
 146         }
 147         /*
 148          * Temporary check to prevent connection recovery for
 149          * connections with a differing Max*DataSegmentLength.
 150          */
 151         if (cr->maxrecvdatasegmentlength !=
 152             conn->conn_ops->MaxRecvDataSegmentLength) {
 153                 pr_err("Unable to perform connection recovery for"
 154                         " differing MaxRecvDataSegmentLength, rejecting"
 155                         " TMR TASK_REASSIGN.\n");
 156                 return ISCSI_TMF_RSP_REJECTED;
 157         }
 158         if (cr->maxxmitdatasegmentlength !=
 159             conn->conn_ops->MaxXmitDataSegmentLength) {
 160                 pr_err("Unable to perform connection recovery for"
 161                         " differing MaxXmitDataSegmentLength, rejecting"
 162                         " TMR TASK_REASSIGN.\n");
 163                 return ISCSI_TMF_RSP_REJECTED;
 164         }
 165
 166         ref_lun = scsilun_to_int(&hdr->lun);
 167         if (ref_lun != ref_cmd->se_cmd.orig_fe_lun) {
 168                 pr_err("Unable to perform connection recovery for"
 169                         " differing ref_lun: %d ref_cmd orig_fe_lun: %u\n",
 170                         ref_lun, ref_cmd->se_cmd.orig_fe_lun);
 171                 return ISCSI_TMF_RSP_REJECTED;
 172         }
 173
 174         se_tmr->ref_task_tag            = (__force u32)hdr->rtt;
 175         tmr_req->ref_cmd                = ref_cmd;
 176         tmr_req->exp_data_sn            = be32_to_cpu(hdr->exp_datasn);
 177         tmr_req->conn_recovery          = cr;
 178         tmr_req->task_reassign          = 1;
 179         /*
 180          * Command can now be reassigned to a new connection.
 181          * The task management response must be sent before the
 182          * reassignment actually happens.  See iscsi_tmr_post_handler().
 183          */
 184         return ISCSI_TMF_RSP_COMPLETE;
 185 }
 186
 187 static void iscsit_task_reassign_remove_cmd(
 188         struct iscsi_cmd *cmd,
 189         struct iscsi_conn_recovery *cr,
 190         struct iscsi_session *sess)
 191 {
 192         int ret;
 193
 194         spin_lock(&cr->conn_recovery_cmd_lock);
 195         ret = iscsit_remove_cmd_from_connection_recovery(cmd, sess);
 196         spin_unlock(&cr->conn_recovery_cmd_lock);
 197         if (!ret) {
 198                 pr_debug("iSCSI connection recovery successful for CID:"
 199                         " %hu on SID: %u\n", cr->cid, sess->sid);
 200                 iscsit_remove_active_connection_recovery_entry(cr, sess);
 201         }
 202 }
 203
 204 static int iscsit_task_reassign_complete_nop_out(
 205         struct iscsi_tmr_req *tmr_req,
 206         struct iscsi_conn *conn)
 207 {
 208         struct iscsi_cmd *cmd = tmr_req->ref_cmd;
 209         struct iscsi_conn_recovery *cr;
 210
 211         if (!cmd->cr) {
 212                 pr_err("struct iscsi_conn_recovery pointer for ITT: 0x%08x"
 213                         " is NULL!\n", cmd->init_task_tag);
 214                 return -1;
 215         }
 216         cr = cmd->cr;
 217
 218         /*
 219          * Reset the StatSN so a new one for this commands new connection
 220          * will be assigned.
 221          * Reset the ExpStatSN as well so we may receive Status SNACKs.
 222          */
 223         cmd->stat_sn = cmd->exp_stat_sn = 0;
 224
 225         iscsit_task_reassign_remove_cmd(cmd, cr, conn->sess);
 226
 227         spin_lock_bh(&conn->cmd_lock);
 228         list_add_tail(&cmd->i_conn_node, &conn->conn_cmd_list);
 229         spin_unlock_bh(&conn->cmd_lock);
 230
 231         cmd->i_state = ISTATE_SEND_NOPIN;
 232         iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
 233         return 0;
 234 }
 235
 236 static int iscsit_task_reassign_complete_write(
 237         struct iscsi_cmd *cmd,
 238         struct iscsi_tmr_req *tmr_req)
 239 {
 240         int no_build_r2ts = 0;
 241         u32 length = 0, offset = 0;
 242         struct iscsi_conn *conn = cmd->conn;
 243         struct se_cmd *se_cmd = &cmd->se_cmd;
 244         /*
 245          * The Initiator must not send a R2T SNACK with a Begrun less than
 246          * the TMR TASK_REASSIGN's ExpDataSN.
 247          */
 248         if (!tmr_req->exp_data_sn) {
 249                 cmd->cmd_flags &= ~ICF_GOT_DATACK_SNACK;
 250                 cmd->acked_data_sn = 0;
 251         } else {
 252                 cmd->cmd_flags |= ICF_GOT_DATACK_SNACK;
 253                 cmd->acked_data_sn = (tmr_req->exp_data_sn - 1);
 254         }
 255
 256         /*
 257          * The TMR TASK_REASSIGN's ExpDataSN contains the next R2TSN the
 258          * Initiator is expecting.  The Target controls all WRITE operations
 259          * so if we have received all DataOUT we can safety ignore Initiator.
 260          */
 261         if (cmd->cmd_flags & ICF_GOT_LAST_DATAOUT) {
 262                 if (!(cmd->se_cmd.transport_state & CMD_T_SENT)) {
 263                         pr_debug("WRITE ITT: 0x%08x: t_state: %d"
 264                                 " never sent to transport\n",
 265                                 cmd->init_task_tag, cmd->se_cmd.t_state);
 266                         target_execute_cmd(se_cmd);
 267                         return 0;
 268                 }
 269
 270                 cmd->i_state = ISTATE_SEND_STATUS;
 271                 iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
 272                 return 0;
 273         }
 274
 275         /*
 276          * Special case to deal with DataSequenceInOrder=No and Non-Immeidate
 277          * Unsolicited DataOut.
 278          */
 279         if (cmd->unsolicited_data) {
 280                 cmd->unsolicited_data = 0;
 281
 282                 offset = cmd->next_burst_len = cmd->write_data_done;
 283
 284                 if ((conn->sess->sess_ops->FirstBurstLength - offset) >=
 285                      cmd->se_cmd.data_length) {
 286                         no_build_r2ts = 1;
 287                         length = (cmd->se_cmd.data_length - offset);
 288                 } else
 289                         length = (conn->sess->sess_ops->FirstBurstLength - offset);
 290
 291                 spin_lock_bh(&cmd->r2t_lock);
 292                 if (iscsit_add_r2t_to_list(cmd, offset, length, 0, 0) < 0) {
 293                         spin_unlock_bh(&cmd->r2t_lock);
 294                         return -1;
 295                 }
 296                 cmd->outstanding_r2ts++;
 297                 spin_unlock_bh(&cmd->r2t_lock);
 298
 299                 if (no_build_r2ts)
 300                         return 0;
 301         }
 302         /*
 303          * iscsit_build_r2ts_for_cmd() can handle the rest from here.
 304          */
 305         return conn->conn_transport->iscsit_get_dataout(conn, cmd, true);
 306 }
 307
 308 static int iscsit_task_reassign_complete_read(
 309         struct iscsi_cmd *cmd,
 310         struct iscsi_tmr_req *tmr_req)
 311 {
 312         struct iscsi_conn *conn = cmd->conn;
 313         struct iscsi_datain_req *dr;
 314         struct se_cmd *se_cmd = &cmd->se_cmd;
 315         /*
 316          * The Initiator must not send a Data SNACK with a BegRun less than
 317          * the TMR TASK_REASSIGN's ExpDataSN.
 318          */
 319         if (!tmr_req->exp_data_sn) {
 320                 cmd->cmd_flags &= ~ICF_GOT_DATACK_SNACK;
 321                 cmd->acked_data_sn = 0;
 322         } else {
 323                 cmd->cmd_flags |= ICF_GOT_DATACK_SNACK;
 324                 cmd->acked_data_sn = (tmr_req->exp_data_sn - 1);
 325         }
 326
 327         if (!(cmd->se_cmd.transport_state & CMD_T_SENT)) {
 328                 pr_debug("READ ITT: 0x%08x: t_state: %d never sent to"
 329                         " transport\n", cmd->init_task_tag,
 330                         cmd->se_cmd.t_state);
 331                 transport_handle_cdb_direct(se_cmd);
 332                 return 0;
 333         }
 334
 335         if (!(se_cmd->transport_state & CMD_T_COMPLETE)) {
 336                 pr_err("READ ITT: 0x%08x: t_state: %d, never returned"
 337                         " from transport\n", cmd->init_task_tag,
 338                         cmd->se_cmd.t_state);
 339                 return -1;
 340         }
 341
 342         dr = iscsit_allocate_datain_req();
 343         if (!dr)
 344                 return -1;
 345         /*
 346          * The TMR TASK_REASSIGN's ExpDataSN contains the next DataSN the
 347          * Initiator is expecting.
 348          */
 349         dr->data_sn = dr->begrun = tmr_req->exp_data_sn;
 350         dr->runlength = 0;
 351         dr->generate_recovery_values = 1;
 352         dr->recovery = DATAIN_CONNECTION_RECOVERY;
 353
 354         iscsit_attach_datain_req(cmd, dr);
 355
 356         cmd->i_state = ISTATE_SEND_DATAIN;
 357         iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
 358         return 0;
 359 }
 360
 361 static int iscsit_task_reassign_complete_none(
 362         struct iscsi_cmd *cmd,
 363         struct iscsi_tmr_req *tmr_req)
 364 {
 365         struct iscsi_conn *conn = cmd->conn;
 366
 367         cmd->i_state = ISTATE_SEND_STATUS;
 368         iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
 369         return 0;
 370 }
 371
 372 static int iscsit_task_reassign_complete_scsi_cmnd(
 373         struct iscsi_tmr_req *tmr_req,
 374         struct iscsi_conn *conn)
 375 {
 376         struct iscsi_cmd *cmd = tmr_req->ref_cmd;
 377         struct iscsi_conn_recovery *cr;
 378
 379         if (!cmd->cr) {
 380                 pr_err("struct iscsi_conn_recovery pointer for ITT: 0x%08x"
 381                         " is NULL!\n", cmd->init_task_tag);
 382                 return -1;
 383         }
 384         cr = cmd->cr;
 385
 386         /*
 387          * Reset the StatSN so a new one for this commands new connection
 388          * will be assigned.
 389          * Reset the ExpStatSN as well so we may receive Status SNACKs.
 390          */
 391         cmd->stat_sn = cmd->exp_stat_sn = 0;
 392
 393         iscsit_task_reassign_remove_cmd(cmd, cr, conn->sess);
 394
 395         spin_lock_bh(&conn->cmd_lock);
 396         list_add_tail(&cmd->i_conn_node, &conn->conn_cmd_list);
 397         spin_unlock_bh(&conn->cmd_lock);
 398
 399         if (cmd->se_cmd.se_cmd_flags & SCF_SENT_CHECK_CONDITION) {
 400                 cmd->i_state = ISTATE_SEND_STATUS;
 401                 iscsit_add_cmd_to_response_queue(cmd, conn, cmd->i_state);
 402                 return 0;
 403         }
 404
 405         switch (cmd->data_direction) {
 406         case DMA_TO_DEVICE:
 407                 return iscsit_task_reassign_complete_write(cmd, tmr_req);
 408         case DMA_FROM_DEVICE:
 409                 return iscsit_task_reassign_complete_read(cmd, tmr_req);
 410         case DMA_NONE:
 411                 return iscsit_task_reassign_complete_none(cmd, tmr_req);
 412         default:
 413                 pr_err("Unknown cmd->data_direction: 0x%02x\n",
 414                                 cmd->data_direction);
 415                 return -1;
 416         }
 417
 418         return 0;
 419 }
 420
 421 static int iscsit_task_reassign_complete(
 422         struct iscsi_tmr_req *tmr_req,
 423         struct iscsi_conn *conn)
 424 {
 425         struct iscsi_cmd *cmd;
 426         int ret = 0;
 427
 428         if (!tmr_req->ref_cmd) {
 429                 pr_err("TMR Request is missing a RefCmd struct iscsi_cmd.\n");
 430                 return -1;
 431         }
 432         cmd = tmr_req->ref_cmd;
 433
 434         cmd->conn = conn;
 435
 436         switch (cmd->iscsi_opcode) {
 437         case ISCSI_OP_NOOP_OUT:
 438                 ret = iscsit_task_reassign_complete_nop_out(tmr_req, conn);
 439                 break;
 440         case ISCSI_OP_SCSI_CMD:
 441                 ret = iscsit_task_reassign_complete_scsi_cmnd(tmr_req, conn);
 442                 break;
 443         default:
 444                  pr_err("Illegal iSCSI Opcode 0x%02x during"
 445                         " command realligence\n", cmd->iscsi_opcode);
 446                 return -1;
 447         }
 448
 449         if (ret != 0)
 450                 return ret;
 451
 452         pr_debug("Completed connection realligence for Opcode: 0x%02x,"
 453                 " ITT: 0x%08x to CID: %hu.\n", cmd->iscsi_opcode,
 454                         cmd->init_task_tag, conn->cid);
 455
 456         return 0;
 457 }
 458
 459 /*
 460  *      Handles special after-the-fact actions related to TMRs.
 461  *      Right now the only one that its really needed for is
 462  *      connection recovery releated TASK_REASSIGN.
 463  */
 464 int iscsit_tmr_post_handler(struct iscsi_cmd *cmd, struct iscsi_conn *conn)
 465 {
 466         struct iscsi_tmr_req *tmr_req = cmd->tmr_req;
 467         struct se_tmr_req *se_tmr = cmd->se_cmd.se_tmr_req;
 468
 469         if (tmr_req->task_reassign &&
 470            (se_tmr->response == ISCSI_TMF_RSP_COMPLETE))
 471                 return iscsit_task_reassign_complete(tmr_req, conn);
 472
 473         return 0;
 474 }
 475 EXPORT_SYMBOL(iscsit_tmr_post_handler);
 476
 477 /*
 478  *      Nothing to do here, but leave it for good measure. :-)
 479  */
 480 static int iscsit_task_reassign_prepare_read(
 481         struct iscsi_tmr_req *tmr_req,
 482         struct iscsi_conn *conn)
 483 {
 484         return 0;
 485 }
 486
 487 static void iscsit_task_reassign_prepare_unsolicited_dataout(
 488         struct iscsi_cmd *cmd,
 489         struct iscsi_conn *conn)
 490 {
 491         int i, j;
 492         struct iscsi_pdu *pdu = NULL;
 493         struct iscsi_seq *seq = NULL;
 494
 495         if (conn->sess->sess_ops->DataSequenceInOrder) {
 496                 cmd->data_sn = 0;
 497
 498                 if (cmd->immediate_data)
 499                         cmd->r2t_offset += (cmd->first_burst_len -
 500                                 cmd->seq_start_offset);
 501
 502                 if (conn->sess->sess_ops->DataPDUInOrder) {
 503                         cmd->write_data_done -= (cmd->immediate_data) ?
 504                                                 (cmd->first_burst_len -
 505                                                  cmd->seq_start_offset) :
 506                                                  cmd->first_burst_len;
 507                         cmd->first_burst_len = 0;
 508                         return;
 509                 }
 510
 511                 for (i = 0; i < cmd->pdu_count; i++) {
 512                         pdu = &cmd->pdu_list[i];
 513
 514                         if (pdu->status != ISCSI_PDU_RECEIVED_OK)
 515                                 continue;
 516
 517                         if ((pdu->offset >= cmd->seq_start_offset) &&
 518                            ((pdu->offset + pdu->length) <=
 519                              cmd->seq_end_offset)) {
 520                                 cmd->first_burst_len -= pdu->length;
 521                                 cmd->write_data_done -= pdu->length;
 522                                 pdu->status = ISCSI_PDU_NOT_RECEIVED;
 523                         }
 524                 }
 525         } else {
 526                 for (i = 0; i < cmd->seq_count; i++) {
 527                         seq = &cmd->seq_list[i];
 528
 529                         if (seq->type != SEQTYPE_UNSOLICITED)
 530                                 continue;
 531
 532                         cmd->write_data_done -=
 533                                         (seq->offset - seq->orig_offset);
 534                         cmd->first_burst_len = 0;
 535                         seq->data_sn = 0;
 536                         seq->offset = seq->orig_offset;
 537                         seq->next_burst_len = 0;
 538                         seq->status = DATAOUT_SEQUENCE_WITHIN_COMMAND_RECOVERY;
 539
 540                         if (conn->sess->sess_ops->DataPDUInOrder)
 541                                 continue;
 542
 543                         for (j = 0; j < seq->pdu_count; j++) {
 544                                 pdu = &cmd->pdu_list[j+seq->pdu_start];
 545
 546                                 if (pdu->status != ISCSI_PDU_RECEIVED_OK)
 547                                         continue;
 548
 549                                 pdu->status = ISCSI_PDU_NOT_RECEIVED;
 550                         }
 551                 }
 552         }
 553 }
 554
 555 static int iscsit_task_reassign_prepare_write(
 556         struct iscsi_tmr_req *tmr_req,
 557         struct iscsi_conn *conn)
 558 {
 559         struct iscsi_cmd *cmd = tmr_req->ref_cmd;
 560         struct iscsi_pdu *pdu = NULL;
 561         struct iscsi_r2t *r2t = NULL, *r2t_tmp;
 562         int first_incomplete_r2t = 1, i = 0;
 563
 564         /*
 565          * The command was in the process of receiving Unsolicited DataOUT when
 566          * the connection failed.
 567          */
 568         if (cmd->unsolicited_data)
 569                 iscsit_task_reassign_prepare_unsolicited_dataout(cmd, conn);
 570
 571         /*
 572          * The Initiator is requesting R2Ts starting from zero,  skip
 573          * checking acknowledged R2Ts and start checking struct iscsi_r2ts
 574          * greater than zero.
 575          */
 576         if (!tmr_req->exp_data_sn)
 577                 goto drop_unacknowledged_r2ts;
 578
 579         /*
 580          * We now check that the PDUs in DataOUT sequences below
 581          * the TMR TASK_REASSIGN ExpDataSN (R2TSN the Initiator is
 582          * expecting next) have all the DataOUT they require to complete
 583          * the DataOUT sequence.  First scan from R2TSN 0 to TMR
 584          * TASK_REASSIGN ExpDataSN-1.
 585          *
 586          * If we have not received all DataOUT in question,  we must
 587          * make sure to make the appropriate changes to values in
 588          * struct iscsi_cmd (and elsewhere depending on session parameters)
 589          * so iscsit_build_r2ts_for_cmd() in iscsit_task_reassign_complete_write()
 590          * will resend a new R2T for the DataOUT sequences in question.
 591          */
 592         spin_lock_bh(&cmd->r2t_lock);
 593         if (list_empty(&cmd->cmd_r2t_list)) {
 594                 spin_unlock_bh(&cmd->r2t_lock);
 595                 return -1;
 596         }
 597
 598         list_for_each_entry(r2t, &cmd->cmd_r2t_list, r2t_list) {
 599
 600                 if (r2t->r2t_sn >= tmr_req->exp_data_sn)
 601                         continue;
 602                 /*
 603                  * Safely ignore Recovery R2Ts and R2Ts that have completed
 604                  * DataOUT sequences.
 605                  */
 606                 if (r2t->seq_complete)
 607                         continue;
 608
 609                 if (r2t->recovery_r2t)
 610                         continue;
 611
 612                 /*
 613                  *                 DataSequenceInOrder=Yes:
 614                  *
 615                  * Taking into account the iSCSI implementation requirement of
 616                  * MaxOutstandingR2T=1 while ErrorRecoveryLevel>0 and
 617                  * DataSequenceInOrder=Yes, we must take into consideration
 618                  * the following:
 619                  *
 620                  *                  DataSequenceInOrder=No:
 621                  *
 622                  * Taking into account that the Initiator controls the (possibly
 623                  * random) PDU Order in (possibly random) Sequence Order of
 624                  * DataOUT the target requests with R2Ts,  we must take into
 625                  * consideration the following:
 626                  *
 627                  *      DataPDUInOrder=Yes for DataSequenceInOrder=[Yes,No]:
 628                  *
 629                  * While processing non-complete R2T DataOUT sequence requests
 630                  * the Target will re-request only the total sequence length
 631                  * minus current received offset.  This is because we must
 632                  * assume the initiator will continue sending DataOUT from the
 633                  * last PDU before the connection failed.
 634                  *
 635                  *      DataPDUInOrder=No for DataSequenceInOrder=[Yes,No]:
 636                  *
 637                  * While processing non-complete R2T DataOUT sequence requests
 638                  * the Target will re-request the entire DataOUT sequence if
 639                  * any single PDU is missing from the sequence.  This is because
 640                  * we have no logical method to determine the next PDU offset,
 641                  * and we must assume the Initiator will be sending any random
 642                  * PDU offset in the current sequence after TASK_REASSIGN
 643                  * has completed.
 644                  */
 645                 if (conn->sess->sess_ops->DataSequenceInOrder) {
 646                         if (!first_incomplete_r2t) {
 647                                 cmd->r2t_offset -= r2t->xfer_len;
 648                                 goto next;
 649                         }
 650
 651                         if (conn->sess->sess_ops->DataPDUInOrder) {
 652                                 cmd->data_sn = 0;
 653                                 cmd->r2t_offset -= (r2t->xfer_len -
 654                                         cmd->next_burst_len);
 655                                 first_incomplete_r2t = 0;
 656                                 goto next;
 657                         }
 658
 659                         cmd->data_sn = 0;
 660                         cmd->r2t_offset -= r2t->xfer_len;
 661
 662                         for (i = 0; i < cmd->pdu_count; i++) {
 663                                 pdu = &cmd->pdu_list[i];
 664
 665                                 if (pdu->status != ISCSI_PDU_RECEIVED_OK)
 666                                         continue;
 667
 668                                 if ((pdu->offset >= r2t->offset) &&
 669                                     (pdu->offset < (r2t->offset +
 670                                                 r2t->xfer_len))) {
 671                                         cmd->next_burst_len -= pdu->length;
 672                                         cmd->write_data_done -= pdu->length;
 673                                         pdu->status = ISCSI_PDU_NOT_RECEIVED;
 674                                 }
 675                         }
 676
 677                         first_incomplete_r2t = 0;
 678                 } else {
 679                         struct iscsi_seq *seq;
 680
 681                         seq = iscsit_get_seq_holder(cmd, r2t->offset,
 682                                         r2t->xfer_len);
 683                         if (!seq) {
 684                                 spin_unlock_bh(&cmd->r2t_lock);
 685                                 return -1;
 686                         }
 687
 688                         cmd->write_data_done -=
 689                                         (seq->offset - seq->orig_offset);
 690                         seq->data_sn = 0;
 691                         seq->offset = seq->orig_offset;
 692                         seq->next_burst_len = 0;
 693                         seq->status = DATAOUT_SEQUENCE_WITHIN_COMMAND_RECOVERY;
 694
 695                         cmd->seq_send_order--;
 696
 697                         if (conn->sess->sess_ops->DataPDUInOrder)
 698                                 goto next;
 699
 700                         for (i = 0; i < seq->pdu_count; i++) {
 701                                 pdu = &cmd->pdu_list[i+seq->pdu_start];
 702
 703                                 if (pdu->status != ISCSI_PDU_RECEIVED_OK)
 704                                         continue;
 705
 706                                 pdu->status = ISCSI_PDU_NOT_RECEIVED;
 707                         }
 708                 }
 709
 710 next:
 711                 cmd->outstanding_r2ts--;
 712         }
 713         spin_unlock_bh(&cmd->r2t_lock);
 714
 715         /*
 716          * We now drop all unacknowledged R2Ts, ie: ExpDataSN from TMR
 717          * TASK_REASSIGN to the last R2T in the list..  We are also careful
 718          * to check that the Initiator is not requesting R2Ts for DataOUT
 719          * sequences it has already completed.
 720          *
 721          * Free each R2T in question and adjust values in struct iscsi_cmd
 722          * accordingly so iscsit_build_r2ts_for_cmd() do the rest of
 723          * the work after the TMR TASK_REASSIGN Response is sent.
 724          */
 725 drop_unacknowledged_r2ts:
 726
 727         cmd->cmd_flags &= ~ICF_SENT_LAST_R2T;
 728         cmd->r2t_sn = tmr_req->exp_data_sn;
 729
 730         spin_lock_bh(&cmd->r2t_lock);
 731         list_for_each_entry_safe(r2t, r2t_tmp, &cmd->cmd_r2t_list, r2t_list) {
 732                 /*
 733                  * Skip up to the R2T Sequence number provided by the
 734                  * iSCSI TASK_REASSIGN TMR
 735                  */
 736                 if (r2t->r2t_sn < tmr_req->exp_data_sn)
 737                         continue;
 738
 739                 if (r2t->seq_complete) {
 740                         pr_err("Initiator is requesting R2Ts from"
 741                                 " R2TSN: 0x%08x, but R2TSN: 0x%08x, Offset: %u,"
 742                                 " Length: %u is already complete."
 743                                 "   BAD INITIATOR ERL=2 IMPLEMENTATION!\n",
 744                                 tmr_req->exp_data_sn, r2t->r2t_sn,
 745                                 r2t->offset, r2t->xfer_len);
 746                         spin_unlock_bh(&cmd->r2t_lock);
 747                         return -1;
 748                 }
 749
 750                 if (r2t->recovery_r2t) {
 751                         iscsit_free_r2t(r2t, cmd);
 752                         continue;
 753                 }
 754
 755                 /*                 DataSequenceInOrder=Yes:
 756                  *
 757                  * Taking into account the iSCSI implementation requirement of
 758                  * MaxOutstandingR2T=1 while ErrorRecoveryLevel>0 and
 759                  * DataSequenceInOrder=Yes, it's safe to subtract the R2Ts
 760                  * entire transfer length from the commands R2T offset marker.
 761                  *
 762                  *                 DataSequenceInOrder=No:
 763                  *
 764                  * We subtract the difference from struct iscsi_seq between the
 765                  * current offset and original offset from cmd->write_data_done
 766                  * for account for DataOUT PDUs already received.  Then reset
 767                  * the current offset to the original and zero out the current
 768                  * burst length,  to make sure we re-request the entire DataOUT
 769                  * sequence.
 770                  */
 771                 if (conn->sess->sess_ops->DataSequenceInOrder)
 772                         cmd->r2t_offset -= r2t->xfer_len;
 773                 else
 774                         cmd->seq_send_order--;
 775
 776                 cmd->outstanding_r2ts--;
 777                 iscsit_free_r2t(r2t, cmd);
 778         }
 779         spin_unlock_bh(&cmd->r2t_lock);
 780
 781         return 0;
 782 }
 783
 784 /*
 785  *      Performs sanity checks TMR TASK_REASSIGN's ExpDataSN for
 786  *      a given struct iscsi_cmd.
 787  */
 788 int iscsit_check_task_reassign_expdatasn(
 789         struct iscsi_tmr_req *tmr_req,
 790         struct iscsi_conn *conn)
 791 {
 792         struct iscsi_cmd *ref_cmd = tmr_req->ref_cmd;
 793
 794         if (ref_cmd->iscsi_opcode != ISCSI_OP_SCSI_CMD)
 795                 return 0;
 796
 797         if (ref_cmd->se_cmd.se_cmd_flags & SCF_SENT_CHECK_CONDITION)
 798                 return 0;
 799
 800         if (ref_cmd->data_direction == DMA_NONE)
 801                 return 0;
 802
 803         /*
 804          * For READs the TMR TASK_REASSIGNs ExpDataSN contains the next DataSN
 805          * of DataIN the Initiator is expecting.
 806          *
 807          * Also check that the Initiator is not re-requesting DataIN that has
 808          * already been acknowledged with a DataAck SNACK.
 809          */
 810         if (ref_cmd->data_direction == DMA_FROM_DEVICE) {
 811                 if (tmr_req->exp_data_sn > ref_cmd->data_sn) {
 812                         pr_err("Received ExpDataSN: 0x%08x for READ"
 813                                 " in TMR TASK_REASSIGN greater than command's"
 814                                 " DataSN: 0x%08x.\n", tmr_req->exp_data_sn,
 815                                 ref_cmd->data_sn);
 816                         return -1;
 817                 }
 818                 if ((ref_cmd->cmd_flags & ICF_GOT_DATACK_SNACK) &&
 819                     (tmr_req->exp_data_sn <= ref_cmd->acked_data_sn)) {
 820                         pr_err("Received ExpDataSN: 0x%08x for READ"
 821                                 " in TMR TASK_REASSIGN for previously"
 822                                 " acknowledged DataIN: 0x%08x,"
 823                                 " protocol error\n", tmr_req->exp_data_sn,
 824                                 ref_cmd->acked_data_sn);
 825                         return -1;
 826                 }
 827                 return iscsit_task_reassign_prepare_read(tmr_req, conn);
 828         }
 829
 830         /*
 831          * For WRITEs the TMR TASK_REASSIGNs ExpDataSN contains the next R2TSN
 832          * for R2Ts the Initiator is expecting.
 833          *
 834          * Do the magic in iscsit_task_reassign_prepare_write().
 835          */
 836         if (ref_cmd->data_direction == DMA_TO_DEVICE) {
 837                 if (tmr_req->exp_data_sn > ref_cmd->r2t_sn) {
 838                         pr_err("Received ExpDataSN: 0x%08x for WRITE"
 839                                 " in TMR TASK_REASSIGN greater than command's"
 840                                 " R2TSN: 0x%08x.\n", tmr_req->exp_data_sn,
 841                                         ref_cmd->r2t_sn);
 842                         return -1;
 843                 }
 844                 return iscsit_task_reassign_prepare_write(tmr_req, conn);
 845         }
 846
 847         pr_err("Unknown iSCSI data_direction: 0x%02x\n",
 848                         ref_cmd->data_direction);
 849
 850         return -1;
 851 }