iscsi_target_erl0.c

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/******************************************************************************
 * This file contains error recovery level zero functions used by
 * the iSCSI Target driver.
 *
 * \u00a9 Copyright 2007-2011 RisingTide Systems LLC.
 *
 * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
 *
 * Author: Nicholas A. Bellinger <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 ******************************************************************************/

#include <scsi/iscsi_proto.h>
#include <target/target_core_base.h>
#include <target/target_core_fabric.h>

#include "iscsi_target_core.h"
#include "iscsi_target_seq_pdu_list.h"
#include "iscsi_target_tq.h"
#include "iscsi_target_erl0.h"
#include "iscsi_target_erl1.h"
#include "iscsi_target_erl2.h"
#include "iscsi_target_util.h"
#include "iscsi_target.h"

/*
 *  Used to set values in struct iscsi_cmd that iscsit_dataout_check_sequence()
 *  checks against to determine a PDU's Offset+Length is within the current
 *  DataOUT Sequence.  Used for DataSequenceInOrder=Yes only.
 */
void iscsit_set_dataout_sequence_values(
    struct iscsi_cmd *cmd)
{
    struct iscsi_conn *conn = cmd->conn;
    /*
     * Still set seq_start_offset and seq_end_offset for Unsolicited
     * DataOUT, even if DataSequenceInOrder=No.
     */
    if (cmd->unsolicited_data) {
        cmd->seq_start_offset = cmd->write_data_done;
        cmd->seq_end_offset = (cmd->write_data_done +
            ((cmd->se_cmd.data_length >
              conn->sess->sess_ops->FirstBurstLength) ?
             conn->sess->sess_ops->FirstBurstLength : cmd->se_cmd.data_length));
        return;
    }

    if (!conn->sess->sess_ops->DataSequenceInOrder)
        return;

    if (!cmd->seq_start_offset && !cmd->seq_end_offset) {
        cmd->seq_start_offset = cmd->write_data_done;
        cmd->seq_end_offset = (cmd->se_cmd.data_length >
            conn->sess->sess_ops->MaxBurstLength) ?
            (cmd->write_data_done +
            conn->sess->sess_ops->MaxBurstLength) : cmd->se_cmd.data_length;
    } else {
        cmd->seq_start_offset = cmd->seq_end_offset;
        cmd->seq_end_offset = ((cmd->seq_end_offset +
            conn->sess->sess_ops->MaxBurstLength) >=
            cmd->se_cmd.data_length) ? cmd->se_cmd.data_length :
            (cmd->seq_end_offset +
             conn->sess->sess_ops->MaxBurstLength);
    }
}

static int iscsit_dataout_within_command_recovery_check(
    struct iscsi_cmd *cmd,
    unsigned char *buf)
{
    struct iscsi_conn *conn = cmd->conn;
    struct iscsi_data *hdr = (struct iscsi_data *) buf;
    u32 payload_length = ntoh24(hdr->dlength);

    /*
     * We do the within-command recovery checks here as it is
     * the first function called in iscsi_check_pre_dataout().
     * Basically, if we are in within-command recovery and
     * the PDU does not contain the offset the sequence needs,
     * dump the payload.
     *
     * This only applies to DataPDUInOrder=Yes, for
     * DataPDUInOrder=No we only re-request the failed PDU
     * and check that all PDUs in a sequence are received
     * upon end of sequence.
     */
    if (conn->sess->sess_ops->DataSequenceInOrder) {
        if ((cmd->cmd_flags & ICF_WITHIN_COMMAND_RECOVERY) &&
            cmd->write_data_done != be32_to_cpu(hdr->offset))
            goto dump;

        cmd->cmd_flags &= ~ICF_WITHIN_COMMAND_RECOVERY;
    } else {
        struct iscsi_seq *seq;

        seq = iscsit_get_seq_holder(cmd, be32_to_cpu(hdr->offset),
                        payload_length);
        if (!seq)
            return DATAOUT_CANNOT_RECOVER;
        /*
         * Set the struct iscsi_seq pointer to reuse later.
         */
        cmd->seq_ptr = seq;

        if (conn->sess->sess_ops->DataPDUInOrder) {
            if (seq->status ==
                DATAOUT_SEQUENCE_WITHIN_COMMAND_RECOVERY &&
               (seq->offset != be32_to_cpu(hdr->offset) ||
                seq->data_sn != be32_to_cpu(hdr->datasn)))
                goto dump;
        } else {
            if (seq->status ==
                 DATAOUT_SEQUENCE_WITHIN_COMMAND_RECOVERY &&
                seq->data_sn != be32_to_cpu(hdr->datasn))
                goto dump;
        }

        if (seq->status == DATAOUT_SEQUENCE_COMPLETE)
            goto dump;

        if (seq->status != DATAOUT_SEQUENCE_COMPLETE)
            seq->status = 0;
    }

    return DATAOUT_NORMAL;

dump:
    pr_err("Dumping DataOUT PDU Offset: %u Length: %d DataSN:"
        " 0x%08x\n", hdr->offset, payload_length, hdr->datasn);
    return iscsit_dump_data_payload(conn, payload_length, 1);
}

static int iscsit_dataout_check_unsolicited_sequence(
    struct iscsi_cmd *cmd,
    unsigned char *buf)
{
    u32 first_burst_len;
    struct iscsi_conn *conn = cmd->conn;
    struct iscsi_data *hdr = (struct iscsi_data *) buf;
    u32 payload_length = ntoh24(hdr->dlength);


    if ((be32_to_cpu(hdr->offset) < cmd->seq_start_offset) ||
       ((be32_to_cpu(hdr->offset) + payload_length) > cmd->seq_end_offset)) {
        pr_err("Command ITT: 0x%08x with Offset: %u,"
        " Length: %u outside of Unsolicited Sequence %u:%u while"
        " DataSequenceInOrder=Yes.\n", cmd->init_task_tag,
        be32_to_cpu(hdr->offset), payload_length, cmd->seq_start_offset,
            cmd->seq_end_offset);
        return DATAOUT_CANNOT_RECOVER;
    }

    first_burst_len = (cmd->first_burst_len + payload_length);

    if (first_burst_len > conn->sess->sess_ops->FirstBurstLength) {
        pr_err("Total %u bytes exceeds FirstBurstLength: %u"
            " for this Unsolicited DataOut Burst.\n",
            first_burst_len, conn->sess->sess_ops->FirstBurstLength);
        transport_send_check_condition_and_sense(&cmd->se_cmd,
                TCM_INCORRECT_AMOUNT_OF_DATA, 0);
        return DATAOUT_CANNOT_RECOVER;
    }

    /*
     * Perform various MaxBurstLength and ISCSI_FLAG_CMD_FINAL sanity
     * checks for the current Unsolicited DataOUT Sequence.
     */
    if (hdr->flags & ISCSI_FLAG_CMD_FINAL) {
        /*
         * Ignore ISCSI_FLAG_CMD_FINAL checks while DataPDUInOrder=No, end of
         * sequence checks are handled in
         * iscsit_dataout_datapduinorder_no_fbit().
         */
        if (!conn->sess->sess_ops->DataPDUInOrder)
            goto out;

        if ((first_burst_len != cmd->se_cmd.data_length) &&
            (first_burst_len != conn->sess->sess_ops->FirstBurstLength)) {
            pr_err("Unsolicited non-immediate data"
            " received %u does not equal FirstBurstLength: %u, and"
            " does not equal ExpXferLen %u.\n", first_burst_len,
                conn->sess->sess_ops->FirstBurstLength,
                cmd->se_cmd.data_length);
            transport_send_check_condition_and_sense(&cmd->se_cmd,
                    TCM_INCORRECT_AMOUNT_OF_DATA, 0);
            return DATAOUT_CANNOT_RECOVER;
        }
    } else {
        if (first_burst_len == conn->sess->sess_ops->FirstBurstLength) {
            pr_err("Command ITT: 0x%08x reached"
            " FirstBurstLength: %u, but ISCSI_FLAG_CMD_FINAL is not set. protocol"
                " error.\n", cmd->init_task_tag,
                conn->sess->sess_ops->FirstBurstLength);
            return DATAOUT_CANNOT_RECOVER;
        }
        if (first_burst_len == cmd->se_cmd.data_length) {
            pr_err("Command ITT: 0x%08x reached"
            " ExpXferLen: %u, but ISCSI_FLAG_CMD_FINAL is not set. protocol"
            " error.\n", cmd->init_task_tag, cmd->se_cmd.data_length);
            return DATAOUT_CANNOT_RECOVER;
        }
    }

out:
    return DATAOUT_NORMAL;
}

static int iscsit_dataout_check_sequence(
    struct iscsi_cmd *cmd,
    unsigned char *buf)
{
    u32 next_burst_len;
    struct iscsi_conn *conn = cmd->conn;
    struct iscsi_seq *seq = NULL;
    struct iscsi_data *hdr = (struct iscsi_data *) buf;
    u32 payload_length = ntoh24(hdr->dlength);

    /*
     * For DataSequenceInOrder=Yes: Check that the offset and offset+length
     * is within range as defined by iscsi_set_dataout_sequence_values().
     *
     * For DataSequenceInOrder=No: Check that an struct iscsi_seq exists for
     * offset+length tuple.
     */
    if (conn->sess->sess_ops->DataSequenceInOrder) {
        /*
         * Due to possibility of recovery DataOUT sent by the initiator
         * fullfilling an Recovery R2T, it's best to just dump the
         * payload here, instead of erroring out.
         */
        if ((be32_to_cpu(hdr->offset) < cmd->seq_start_offset) ||
           ((be32_to_cpu(hdr->offset) + payload_length) > cmd->seq_end_offset)) {
            pr_err("Command ITT: 0x%08x with Offset: %u,"
            " Length: %u outside of Sequence %u:%u while"
            " DataSequenceInOrder=Yes.\n", cmd->init_task_tag,
            be32_to_cpu(hdr->offset), payload_length, cmd->seq_start_offset,
                cmd->seq_end_offset);

            if (iscsit_dump_data_payload(conn, payload_length, 1) < 0)
                return DATAOUT_CANNOT_RECOVER;
            return DATAOUT_WITHIN_COMMAND_RECOVERY;
        }

        next_burst_len = (cmd->next_burst_len + payload_length);
    } else {
        seq = iscsit_get_seq_holder(cmd, be32_to_cpu(hdr->offset),
                        payload_length);
        if (!seq)
            return DATAOUT_CANNOT_RECOVER;
        /*
         * Set the struct iscsi_seq pointer to reuse later.
         */
        cmd->seq_ptr = seq;

        if (seq->status == DATAOUT_SEQUENCE_COMPLETE) {
            if (iscsit_dump_data_payload(conn, payload_length, 1) < 0)
                return DATAOUT_CANNOT_RECOVER;
            return DATAOUT_WITHIN_COMMAND_RECOVERY;
        }

        next_burst_len = (seq->next_burst_len + payload_length);
    }

    if (next_burst_len > conn->sess->sess_ops->MaxBurstLength) {
        pr_err("Command ITT: 0x%08x, NextBurstLength: %u and"
            " Length: %u exceeds MaxBurstLength: %u. protocol"
            " error.\n", cmd->init_task_tag,
            (next_burst_len - payload_length),
            payload_length, conn->sess->sess_ops->MaxBurstLength);
        return DATAOUT_CANNOT_RECOVER;
    }

    /*
     * Perform various MaxBurstLength and ISCSI_FLAG_CMD_FINAL sanity
     * checks for the current DataOUT Sequence.
     */
    if (hdr->flags & ISCSI_FLAG_CMD_FINAL) {
        /*
         * Ignore ISCSI_FLAG_CMD_FINAL checks while DataPDUInOrder=No, end of
         * sequence checks are handled in
         * iscsit_dataout_datapduinorder_no_fbit().
         */
        if (!conn->sess->sess_ops->DataPDUInOrder)
            goto out;

        if (conn->sess->sess_ops->DataSequenceInOrder) {
            if ((next_burst_len <
                 conn->sess->sess_ops->MaxBurstLength) &&
               ((cmd->write_data_done + payload_length) <
                 cmd->se_cmd.data_length)) {
                pr_err("Command ITT: 0x%08x set ISCSI_FLAG_CMD_FINAL"
                " before end of DataOUT sequence, protocol"
                " error.\n", cmd->init_task_tag);
                return DATAOUT_CANNOT_RECOVER;
            }
        } else {
            if (next_burst_len < seq->xfer_len) {
                pr_err("Command ITT: 0x%08x set ISCSI_FLAG_CMD_FINAL"
                " before end of DataOUT sequence, protocol"
                " error.\n", cmd->init_task_tag);
                return DATAOUT_CANNOT_RECOVER;
            }
        }
    } else {
        if (conn->sess->sess_ops->DataSequenceInOrder) {
            if (next_burst_len ==
                    conn->sess->sess_ops->MaxBurstLength) {
                pr_err("Command ITT: 0x%08x reached"
                " MaxBurstLength: %u, but ISCSI_FLAG_CMD_FINAL is"
                " not set, protocol error.", cmd->init_task_tag,
                    conn->sess->sess_ops->MaxBurstLength);
                return DATAOUT_CANNOT_RECOVER;
            }
            if ((cmd->write_data_done + payload_length) ==
                    cmd->se_cmd.data_length) {
                pr_err("Command ITT: 0x%08x reached"
                " last DataOUT PDU in sequence but ISCSI_FLAG_"
                "CMD_FINAL is not set, protocol error.\n",
                    cmd->init_task_tag);
                return DATAOUT_CANNOT_RECOVER;
            }
        } else {
            if (next_burst_len == seq->xfer_len) {
                pr_err("Command ITT: 0x%08x reached"
                " last DataOUT PDU in sequence but ISCSI_FLAG_"
                "CMD_FINAL is not set, protocol error.\n",
                    cmd->init_task_tag);
                return DATAOUT_CANNOT_RECOVER;
            }
        }
    }

out:
    return DATAOUT_NORMAL;
}

static int iscsit_dataout_check_datasn(
    struct iscsi_cmd *cmd,
    unsigned char *buf)
{
    int dump = 0, recovery = 0;
    u32 data_sn = 0;
    struct iscsi_conn *conn = cmd->conn;
    struct iscsi_data *hdr = (struct iscsi_data *) buf;
    u32 payload_length = ntoh24(hdr->dlength);

    /*
     * Considering the target has no method of re-requesting DataOUT
     * by DataSN, if we receieve a greater DataSN than expected we
     * assume the functions for DataPDUInOrder=[Yes,No] below will
     * handle it.
     *
     * If the DataSN is less than expected, dump the payload.
     */
    if (conn->sess->sess_ops->DataSequenceInOrder)
        data_sn = cmd->data_sn;
    else {
        struct iscsi_seq *seq = cmd->seq_ptr;
        data_sn = seq->data_sn;
    }

    if (be32_to_cpu(hdr->datasn) > data_sn) {
        pr_err("Command ITT: 0x%08x, received DataSN: 0x%08x"
            " higher than expected 0x%08x.\n", cmd->init_task_tag,
                be32_to_cpu(hdr->datasn), data_sn);
        recovery = 1;
        goto recover;
    } else if (be32_to_cpu(hdr->datasn) < data_sn) {
        pr_err("Command ITT: 0x%08x, received DataSN: 0x%08x"
            " lower than expected 0x%08x, discarding payload.\n",
            cmd->init_task_tag, be32_to_cpu(hdr->datasn), data_sn);
        dump = 1;
        goto dump;
    }

    return DATAOUT_NORMAL;

recover:
    if (!conn->sess->sess_ops->ErrorRecoveryLevel) {
        pr_err("Unable to perform within-command recovery"
                " while ERL=0.\n");
        return DATAOUT_CANNOT_RECOVER;
    }
dump:
    if (iscsit_dump_data_payload(conn, payload_length, 1) < 0)
        return DATAOUT_CANNOT_RECOVER;

    return (recovery || dump) ? DATAOUT_WITHIN_COMMAND_RECOVERY :
                DATAOUT_NORMAL;
}

static int iscsit_dataout_pre_datapduinorder_yes(
    struct iscsi_cmd *cmd,
    unsigned char *buf)
{
    int dump = 0, recovery = 0;
    struct iscsi_conn *conn = cmd->conn;
    struct iscsi_data *hdr = (struct iscsi_data *) buf;
    u32 payload_length = ntoh24(hdr->dlength);

    /*
     * For DataSequenceInOrder=Yes: If the offset is greater than the global
     * DataPDUInOrder=Yes offset counter in struct iscsi_cmd a protcol error has
     * occured and fail the connection.
     *
     * For DataSequenceInOrder=No: If the offset is greater than the per
     * sequence DataPDUInOrder=Yes offset counter in struct iscsi_seq a protocol
     * error has occured and fail the connection.
     */
    if (conn->sess->sess_ops->DataSequenceInOrder) {
        if (be32_to_cpu(hdr->offset) != cmd->write_data_done) {
            pr_err("Command ITT: 0x%08x, received offset"
            " %u different than expected %u.\n", cmd->init_task_tag,
                be32_to_cpu(hdr->offset), cmd->write_data_done);
            recovery = 1;
            goto recover;
        }
    } else {
        struct iscsi_seq *seq = cmd->seq_ptr;

        if (be32_to_cpu(hdr->offset) > seq->offset) {
            pr_err("Command ITT: 0x%08x, received offset"
            " %u greater than expected %u.\n", cmd->init_task_tag,
                be32_to_cpu(hdr->offset), seq->offset);
            recovery = 1;
            goto recover;
        } else if (be32_to_cpu(hdr->offset) < seq->offset) {
            pr_err("Command ITT: 0x%08x, received offset"
            " %u less than expected %u, discarding payload.\n",
                cmd->init_task_tag, be32_to_cpu(hdr->offset),
                seq->offset);
            dump = 1;
            goto dump;
        }
    }

    return DATAOUT_NORMAL;

recover:
    if (!conn->sess->sess_ops->ErrorRecoveryLevel) {
        pr_err("Unable to perform within-command recovery"
                " while ERL=0.\n");
        return DATAOUT_CANNOT_RECOVER;
    }
dump:
    if (iscsit_dump_data_payload(conn, payload_length, 1) < 0)
        return DATAOUT_CANNOT_RECOVER;

    return (recovery) ? iscsit_recover_dataout_sequence(cmd,
        be32_to_cpu(hdr->offset), payload_length) :
           (dump) ? DATAOUT_WITHIN_COMMAND_RECOVERY : DATAOUT_NORMAL;
}

static int iscsit_dataout_pre_datapduinorder_no(
    struct iscsi_cmd *cmd,
    unsigned char *buf)
{
    struct iscsi_pdu *pdu;
    struct iscsi_data *hdr = (struct iscsi_data *) buf;
    u32 payload_length = ntoh24(hdr->dlength);

    pdu = iscsit_get_pdu_holder(cmd, be32_to_cpu(hdr->offset),
                    payload_length);
    if (!pdu)
        return DATAOUT_CANNOT_RECOVER;

    cmd->pdu_ptr = pdu;

    switch (pdu->status) {
    case ISCSI_PDU_NOT_RECEIVED:
    case ISCSI_PDU_CRC_FAILED:
    case ISCSI_PDU_TIMED_OUT:
        break;
    case ISCSI_PDU_RECEIVED_OK:
        pr_err("Command ITT: 0x%08x received already gotten"
            " Offset: %u, Length: %u\n", cmd->init_task_tag,
                be32_to_cpu(hdr->offset), payload_length);
        return iscsit_dump_data_payload(cmd->conn, payload_length, 1);
    default:
        return DATAOUT_CANNOT_RECOVER;
    }

    return DATAOUT_NORMAL;
}

static int iscsit_dataout_update_r2t(struct iscsi_cmd *cmd, u32 offset, u32 length)
{
    struct iscsi_r2t *r2t;

    if (cmd->unsolicited_data)
        return 0;

    r2t = iscsit_get_r2t_for_eos(cmd, offset, length);
    if (!r2t)
        return -1;

    spin_lock_bh(&cmd->r2t_lock);
    r2t->seq_complete = 1;
    cmd->outstanding_r2ts--;
    spin_unlock_bh(&cmd->r2t_lock);

    return 0;
}

static int iscsit_dataout_update_datapduinorder_no(
    struct iscsi_cmd *cmd,
    u32 data_sn,
    int f_bit)
{
    int ret = 0;
    struct iscsi_pdu *pdu = cmd->pdu_ptr;

    pdu->data_sn = data_sn;

    switch (pdu->status) {
    case ISCSI_PDU_NOT_RECEIVED:
        pdu->status = ISCSI_PDU_RECEIVED_OK;
        break;
    case ISCSI_PDU_CRC_FAILED:
        pdu->status = ISCSI_PDU_RECEIVED_OK;
        break;
    case ISCSI_PDU_TIMED_OUT:
        pdu->status = ISCSI_PDU_RECEIVED_OK;
        break;
    default:
        return DATAOUT_CANNOT_RECOVER;
    }

    if (f_bit) {
        ret = iscsit_dataout_datapduinorder_no_fbit(cmd, pdu);
        if (ret == DATAOUT_CANNOT_RECOVER)
            return ret;
    }

    return DATAOUT_NORMAL;
}

static int iscsit_dataout_post_crc_passed(
    struct iscsi_cmd *cmd,
    unsigned char *buf)
{
    int ret, send_r2t = 0;
    struct iscsi_conn *conn = cmd->conn;
    struct iscsi_seq *seq = NULL;
    struct iscsi_data *hdr = (struct iscsi_data *) buf;
    u32 payload_length = ntoh24(hdr->dlength);

    if (cmd->unsolicited_data) {
        if ((cmd->first_burst_len + payload_length) ==
             conn->sess->sess_ops->FirstBurstLength) {
            if (iscsit_dataout_update_r2t(cmd, be32_to_cpu(hdr->offset),
                    payload_length) < 0)
                return DATAOUT_CANNOT_RECOVER;
            send_r2t = 1;
        }

        if (!conn->sess->sess_ops->DataPDUInOrder) {
            ret = iscsit_dataout_update_datapduinorder_no(cmd,
                be32_to_cpu(hdr->datasn),
                (hdr->flags & ISCSI_FLAG_CMD_FINAL));
            if (ret == DATAOUT_CANNOT_RECOVER)
                return ret;
        }

        cmd->first_burst_len += payload_length;

        if (conn->sess->sess_ops->DataSequenceInOrder)
            cmd->data_sn++;
        else {
            seq = cmd->seq_ptr;
            seq->data_sn++;
            seq->offset += payload_length;
        }

        if (send_r2t) {
            if (seq)
                seq->status = DATAOUT_SEQUENCE_COMPLETE;
            cmd->first_burst_len = 0;
            cmd->unsolicited_data = 0;
        }
    } else {
        if (conn->sess->sess_ops->DataSequenceInOrder) {
            if ((cmd->next_burst_len + payload_length) ==
                 conn->sess->sess_ops->MaxBurstLength) {
                if (iscsit_dataout_update_r2t(cmd,
                        be32_to_cpu(hdr->offset),
                        payload_length) < 0)
                    return DATAOUT_CANNOT_RECOVER;
                send_r2t = 1;
            }

            if (!conn->sess->sess_ops->DataPDUInOrder) {
                ret = iscsit_dataout_update_datapduinorder_no(
                        cmd, be32_to_cpu(hdr->datasn),
                        (hdr->flags & ISCSI_FLAG_CMD_FINAL));
                if (ret == DATAOUT_CANNOT_RECOVER)
                    return ret;
            }

            cmd->next_burst_len += payload_length;
            cmd->data_sn++;

            if (send_r2t)
                cmd->next_burst_len = 0;
        } else {
            seq = cmd->seq_ptr;

            if ((seq->next_burst_len + payload_length) ==
                 seq->xfer_len) {
                if (iscsit_dataout_update_r2t(cmd,
                        be32_to_cpu(hdr->offset),
                        payload_length) < 0)
                    return DATAOUT_CANNOT_RECOVER;
                send_r2t = 1;
            }

            if (!conn->sess->sess_ops->DataPDUInOrder) {
                ret = iscsit_dataout_update_datapduinorder_no(
                        cmd, be32_to_cpu(hdr->datasn),
                        (hdr->flags & ISCSI_FLAG_CMD_FINAL));
                if (ret == DATAOUT_CANNOT_RECOVER)
                    return ret;
            }

            seq->data_sn++;
            seq->offset += payload_length;
            seq->next_burst_len += payload_length;

            if (send_r2t) {
                seq->next_burst_len = 0;
                seq->status = DATAOUT_SEQUENCE_COMPLETE;
            }
        }
    }

    if (send_r2t && conn->sess->sess_ops->DataSequenceInOrder)
        cmd->data_sn = 0;

    cmd->write_data_done += payload_length;

    if (cmd->write_data_done == cmd->se_cmd.data_length)
        return DATAOUT_SEND_TO_TRANSPORT;
    else if (send_r2t)
        return DATAOUT_SEND_R2T;
    else
        return DATAOUT_NORMAL;
}

static int iscsit_dataout_post_crc_failed(
    struct iscsi_cmd *cmd,
    unsigned char *buf)
{
    struct iscsi_conn *conn = cmd->conn;
    struct iscsi_pdu *pdu;
    struct iscsi_data *hdr = (struct iscsi_data *) buf;
    u32 payload_length = ntoh24(hdr->dlength);

    if (conn->sess->sess_ops->DataPDUInOrder)
        goto recover;
    /*
     * The rest of this function is only called when DataPDUInOrder=No.
     */
    pdu = cmd->pdu_ptr;

    switch (pdu->status) {
    case ISCSI_PDU_NOT_RECEIVED:
        pdu->status = ISCSI_PDU_CRC_FAILED;
        break;
    case ISCSI_PDU_CRC_FAILED:
        break;
    case ISCSI_PDU_TIMED_OUT:
        pdu->status = ISCSI_PDU_CRC_FAILED;
        break;
    default:
        return DATAOUT_CANNOT_RECOVER;
    }

recover:
    return iscsit_recover_dataout_sequence(cmd, be32_to_cpu(hdr->offset),
                        payload_length);
}

/*
 *  Called from iscsit_handle_data_out() before DataOUT Payload is received
 *  and CRC computed.
 */
int iscsit_check_pre_dataout(
    struct iscsi_cmd *cmd,
    unsigned char *buf)
{
    int ret;
    struct iscsi_conn *conn = cmd->conn;

    ret = iscsit_dataout_within_command_recovery_check(cmd, buf);
    if ((ret == DATAOUT_WITHIN_COMMAND_RECOVERY) ||
        (ret == DATAOUT_CANNOT_RECOVER))
        return ret;

    ret = iscsit_dataout_check_datasn(cmd, buf);
    if ((ret == DATAOUT_WITHIN_COMMAND_RECOVERY) ||
        (ret == DATAOUT_CANNOT_RECOVER))
        return ret;

    if (cmd->unsolicited_data) {
        ret = iscsit_dataout_check_unsolicited_sequence(cmd, buf);
        if ((ret == DATAOUT_WITHIN_COMMAND_RECOVERY) ||
            (ret == DATAOUT_CANNOT_RECOVER))
            return ret;
    } else {
        ret = iscsit_dataout_check_sequence(cmd, buf);
        if ((ret == DATAOUT_WITHIN_COMMAND_RECOVERY) ||
            (ret == DATAOUT_CANNOT_RECOVER))
            return ret;
    }

    return (conn->sess->sess_ops->DataPDUInOrder) ?
        iscsit_dataout_pre_datapduinorder_yes(cmd, buf) :
        iscsit_dataout_pre_datapduinorder_no(cmd, buf);
}

/*
 *  Called from iscsit_handle_data_out() after DataOUT Payload is received
 *  and CRC computed.
 */
int iscsit_check_post_dataout(
    struct iscsi_cmd *cmd,
    unsigned char *buf,
    u8 data_crc_failed)
{
    struct iscsi_conn *conn = cmd->conn;

    cmd->dataout_timeout_retries = 0;

    if (!data_crc_failed)
        return iscsit_dataout_post_crc_passed(cmd, buf);
    else {
        if (!conn->sess->sess_ops->ErrorRecoveryLevel) {
            pr_err("Unable to recover from DataOUT CRC"
                " failure while ERL=0, closing session.\n");
            iscsit_add_reject_from_cmd(ISCSI_REASON_DATA_DIGEST_ERROR,
                    1, 0, buf, cmd);
            return DATAOUT_CANNOT_RECOVER;
        }

        iscsit_add_reject_from_cmd(ISCSI_REASON_DATA_DIGEST_ERROR,
                0, 0, buf, cmd);
        return iscsit_dataout_post_crc_failed(cmd, buf);
    }
}

static void iscsit_handle_time2retain_timeout(unsigned long data)
{
    struct iscsi_session *sess = (struct iscsi_session *) data;
    struct iscsi_portal_group *tpg = ISCSI_TPG_S(sess);
    struct se_portal_group *se_tpg = &tpg->tpg_se_tpg;

    spin_lock_bh(&se_tpg->session_lock);
    if (sess->time2retain_timer_flags & ISCSI_TF_STOP) {
        spin_unlock_bh(&se_tpg->session_lock);
        return;
    }
    if (atomic_read(&sess->session_reinstatement)) {
        pr_err("Exiting Time2Retain handler because"
                " session_reinstatement=1\n");
        spin_unlock_bh(&se_tpg->session_lock);
        return;
    }
    sess->time2retain_timer_flags |= ISCSI_TF_EXPIRED;

    pr_err("Time2Retain timer expired for SID: %u, cleaning up"
            " iSCSI session.\n", sess->sid);
    {
    struct iscsi_tiqn *tiqn = tpg->tpg_tiqn;

    if (tiqn) {
        spin_lock(&tiqn->sess_err_stats.lock);
        strcpy(tiqn->sess_err_stats.last_sess_fail_rem_name,
            (void *)sess->sess_ops->InitiatorName);
        tiqn->sess_err_stats.last_sess_failure_type =
                ISCSI_SESS_ERR_CXN_TIMEOUT;
        tiqn->sess_err_stats.cxn_timeout_errors++;
        sess->conn_timeout_errors++;
        spin_unlock(&tiqn->sess_err_stats.lock);
    }
    }

    spin_unlock_bh(&se_tpg->session_lock);
    target_put_session(sess->se_sess);
}

void iscsit_start_time2retain_handler(struct iscsi_session *sess)
{
    int tpg_active;
    /*
     * Only start Time2Retain timer when the assoicated TPG is still in
     * an ACTIVE (eg: not disabled or shutdown) state.
     */
    spin_lock(&ISCSI_TPG_S(sess)->tpg_state_lock);
    tpg_active = (ISCSI_TPG_S(sess)->tpg_state == TPG_STATE_ACTIVE);
    spin_unlock(&ISCSI_TPG_S(sess)->tpg_state_lock);

    if (!tpg_active)
        return;

    if (sess->time2retain_timer_flags & ISCSI_TF_RUNNING)
        return;

    pr_debug("Starting Time2Retain timer for %u seconds on"
        " SID: %u\n", sess->sess_ops->DefaultTime2Retain, sess->sid);

    init_timer(&sess->time2retain_timer);
    sess->time2retain_timer.expires =
        (get_jiffies_64() + sess->sess_ops->DefaultTime2Retain * HZ);
    sess->time2retain_timer.data = (unsigned long)sess;
    sess->time2retain_timer.function = iscsit_handle_time2retain_timeout;
    sess->time2retain_timer_flags &= ~ISCSI_TF_STOP;
    sess->time2retain_timer_flags |= ISCSI_TF_RUNNING;
    add_timer(&sess->time2retain_timer);
}

/*
 *  Called with spin_lock_bh(&struct se_portal_group->session_lock) held
 */
int iscsit_stop_time2retain_timer(struct iscsi_session *sess)
{
    struct iscsi_portal_group *tpg = ISCSI_TPG_S(sess);
    struct se_portal_group *se_tpg = &tpg->tpg_se_tpg;

    if (sess->time2retain_timer_flags & ISCSI_TF_EXPIRED)
        return -1;

    if (!(sess->time2retain_timer_flags & ISCSI_TF_RUNNING))
        return 0;

    sess->time2retain_timer_flags |= ISCSI_TF_STOP;
    spin_unlock_bh(&se_tpg->session_lock);

    del_timer_sync(&sess->time2retain_timer);

    spin_lock_bh(&se_tpg->session_lock);
    sess->time2retain_timer_flags &= ~ISCSI_TF_RUNNING;
    pr_debug("Stopped Time2Retain Timer for SID: %u\n",
            sess->sid);
    return 0;
}

void iscsit_connection_reinstatement_rcfr(struct iscsi_conn *conn)
{
    spin_lock_bh(&conn->state_lock);
    if (atomic_read(&conn->connection_exit)) {
        spin_unlock_bh(&conn->state_lock);
        goto sleep;
    }

    if (atomic_read(&conn->transport_failed)) {
        spin_unlock_bh(&conn->state_lock);
        goto sleep;
    }
    spin_unlock_bh(&conn->state_lock);

    iscsi_thread_set_force_reinstatement(conn);

sleep:
    wait_for_completion(&conn->conn_wait_rcfr_comp);
    complete(&conn->conn_post_wait_comp);
}

void iscsit_cause_connection_reinstatement(struct iscsi_conn *conn, int sleep)
{
    spin_lock_bh(&conn->state_lock);
    if (atomic_read(&conn->connection_exit)) {
        spin_unlock_bh(&conn->state_lock);
        return;
    }

    if (atomic_read(&conn->transport_failed)) {
        spin_unlock_bh(&conn->state_lock);
        return;
    }

    if (atomic_read(&conn->connection_reinstatement)) {
        spin_unlock_bh(&conn->state_lock);
        return;
    }

    if (iscsi_thread_set_force_reinstatement(conn) < 0) {
        spin_unlock_bh(&conn->state_lock);
        return;
    }

    atomic_set(&conn->connection_reinstatement, 1);
    if (!sleep) {
        spin_unlock_bh(&conn->state_lock);
        return;
    }

    atomic_set(&conn->sleep_on_conn_wait_comp, 1);
    spin_unlock_bh(&conn->state_lock);

    wait_for_completion(&conn->conn_wait_comp);
    complete(&conn->conn_post_wait_comp);
}

void iscsit_fall_back_to_erl0(struct iscsi_session *sess)
{
    pr_debug("Falling back to ErrorRecoveryLevel=0 for SID:"
            " %u\n", sess->sid);

    atomic_set(&sess->session_fall_back_to_erl0, 1);
}

static void iscsit_handle_connection_cleanup(struct iscsi_conn *conn)
{
    struct iscsi_session *sess = conn->sess;

    if ((sess->sess_ops->ErrorRecoveryLevel == 2) &&
        !atomic_read(&sess->session_reinstatement) &&
        !atomic_read(&sess->session_fall_back_to_erl0))
        iscsit_connection_recovery_transport_reset(conn);
    else {
        pr_debug("Performing cleanup for failed iSCSI"
            " Connection ID: %hu from %s\n", conn->cid,
            sess->sess_ops->InitiatorName);
        iscsit_close_connection(conn);
    }
}

void iscsit_take_action_for_connection_exit(struct iscsi_conn *conn)
{
    spin_lock_bh(&conn->state_lock);
    if (atomic_read(&conn->connection_exit)) {
        spin_unlock_bh(&conn->state_lock);
        return;
    }
    atomic_set(&conn->connection_exit, 1);

    if (conn->conn_state == TARG_CONN_STATE_IN_LOGOUT) {
        spin_unlock_bh(&conn->state_lock);
        iscsit_close_connection(conn);
        return;
    }

    if (conn->conn_state == TARG_CONN_STATE_CLEANUP_WAIT) {
        spin_unlock_bh(&conn->state_lock);
        return;
    }

    pr_debug("Moving to TARG_CONN_STATE_CLEANUP_WAIT.\n");
    conn->conn_state = TARG_CONN_STATE_CLEANUP_WAIT;
    spin_unlock_bh(&conn->state_lock);

    iscsit_handle_connection_cleanup(conn);
}

/*
 *  This is the simple function that makes the magic of
 *  sync and steering happen in the follow paradoxical order:
 *
 *  0) Receive conn->of_marker (bytes left until next OFMarker)
 *     bytes into an offload buffer.  When we pass the exact number
 *     of bytes in conn->of_marker, iscsit_dump_data_payload() and hence
 *     rx_data() will automatically receive the identical u32 marker
 *     values and store it in conn->of_marker_offset;
 *  1) Now conn->of_marker_offset will contain the offset to the start
 *     of the next iSCSI PDU.  Dump these remaining bytes into another
 *     offload buffer.
 *  2) We are done!
 *     Next byte in the TCP stream will contain the next iSCSI PDU!
 *     Cool Huh?!
 */
int iscsit_recover_from_unknown_opcode(struct iscsi_conn *conn)
{
    /*
     * Make sure the remaining bytes to next maker is a sane value.
     */
    if (conn->of_marker > (conn->conn_ops->OFMarkInt * 4)) {
        pr_err("Remaining bytes to OFMarker: %u exceeds"
            " OFMarkInt bytes: %u.\n", conn->of_marker,
                conn->conn_ops->OFMarkInt * 4);
        return -1;
    }

    pr_debug("Advancing %u bytes in TCP stream to get to the"
            " next OFMarker.\n", conn->of_marker);

    if (iscsit_dump_data_payload(conn, conn->of_marker, 0) < 0)
        return -1;

    /*
     * Make sure the offset marker we retrived is a valid value.
     */
    if (conn->of_marker_offset > (ISCSI_HDR_LEN + (ISCSI_CRC_LEN * 2) +
        conn->conn_ops->MaxRecvDataSegmentLength)) {
        pr_err("OfMarker offset value: %u exceeds limit.\n",
            conn->of_marker_offset);
        return -1;
    }

    pr_debug("Discarding %u bytes of TCP stream to get to the"
            " next iSCSI Opcode.\n", conn->of_marker_offset);

    if (iscsit_dump_data_payload(conn, conn->of_marker_offset, 0) < 0)
        return -1;

    return 0;
}