/*******************************************************************************
 * Filename:  target_core_transport.c
 *
 * This file contains the Generic Target Engine Core.
 *
 * Copyright (c) 2002, 2003, 2004, 2005 PyX Technologies, Inc.
 * Copyright (c) 2005, 2006, 2007 SBE, Inc.
 * Copyright (c) 2007-2010 Rising Tide Systems
 * Copyright (c) 2008-2010 Linux-iSCSI.org
 *
 * Nicholas A. Bellinger <nab@kernel.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 ******************************************************************************/

#include <linux/net.h>
#include <linux/delay.h>
#include <linux/string.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/spinlock.h>
#include <linux/kthread.h>
#include <linux/in.h>
#include <linux/cdrom.h>
#include <linux/module.h>
#include <linux/ratelimit.h>
#include <asm/unaligned.h>
#include <net/sock.h>
#include <net/tcp.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_tcq.h>

#include <target/target_core_base.h>
#include <target/target_core_backend.h>
#include <target/target_core_fabric.h>
#include <target/target_core_configfs.h>

#include "target_core_internal.h"
#include "target_core_alua.h"
#include "target_core_pr.h"
#include "target_core_ua.h"

static struct workqueue_struct *target_completion_wq;
static struct kmem_cache *se_sess_cache;
struct kmem_cache *se_ua_cache;
struct kmem_cache *t10_pr_reg_cache;
struct kmem_cache *t10_alua_lu_gp_cache;
struct kmem_cache *t10_alua_lu_gp_mem_cache;
struct kmem_cache *t10_alua_tg_pt_gp_cache;
struct kmem_cache *t10_alua_tg_pt_gp_mem_cache;

static void transport_complete_task_attr(struct se_cmd *cmd);
static void transport_handle_queue_full(struct se_cmd *cmd,
                struct se_device *dev);
static int transport_generic_get_mem(struct se_cmd *cmd);
static int target_get_sess_cmd(struct se_session *, struct se_cmd *, bool);
static void transport_put_cmd(struct se_cmd *cmd);
static int transport_set_sense_codes(struct se_cmd *cmd, u8 asc, u8 ascq);
static void target_complete_ok_work(struct work_struct *work);

int init_se_kmem_caches(void)
{
        se_sess_cache = kmem_cache_create("se_sess_cache",
                        sizeof(struct se_session), __alignof__(struct se_session),
                        0, NULL);
        if (!se_sess_cache) {
                pr_err("kmem_cache_create() for struct se_session"
                                " failed\n");
                goto out;
        }
        se_ua_cache = kmem_cache_create("se_ua_cache",
                        sizeof(struct se_ua), __alignof__(struct se_ua),
                        0, NULL);
        if (!se_ua_cache) {
                pr_err("kmem_cache_create() for struct se_ua failed\n");
                goto out_free_sess_cache;
        }
        t10_pr_reg_cache = kmem_cache_create("t10_pr_reg_cache",
                        sizeof(struct t10_pr_registration),
                        __alignof__(struct t10_pr_registration), 0, NULL);
        if (!t10_pr_reg_cache) {
                pr_err("kmem_cache_create() for struct t10_pr_registration"
                                " failed\n");
                goto out_free_ua_cache;
        }
        t10_alua_lu_gp_cache = kmem_cache_create("t10_alua_lu_gp_cache",
                        sizeof(struct t10_alua_lu_gp), __alignof__(struct t10_alua_lu_gp),
                        0, NULL);
        if (!t10_alua_lu_gp_cache) {
                pr_err("kmem_cache_create() for t10_alua_lu_gp_cache"
                                " failed\n");
                goto out_free_pr_reg_cache;
        }
        t10_alua_lu_gp_mem_cache = kmem_cache_create("t10_alua_lu_gp_mem_cache",
                        sizeof(struct t10_alua_lu_gp_member),
                        __alignof__(struct t10_alua_lu_gp_member), 0, NULL);
        if (!t10_alua_lu_gp_mem_cache) {
                pr_err("kmem_cache_create() for t10_alua_lu_gp_mem_"
                                "cache failed\n");
                goto out_free_lu_gp_cache;
        }
        t10_alua_tg_pt_gp_cache = kmem_cache_create("t10_alua_tg_pt_gp_cache",
                        sizeof(struct t10_alua_tg_pt_gp),
                        __alignof__(struct t10_alua_tg_pt_gp), 0, NULL);
        if (!t10_alua_tg_pt_gp_cache) {
                pr_err("kmem_cache_create() for t10_alua_tg_pt_gp_"
                                "cache failed\n");
                goto out_free_lu_gp_mem_cache;
        }
        t10_alua_tg_pt_gp_mem_cache = kmem_cache_create(
                        "t10_alua_tg_pt_gp_mem_cache",
                        sizeof(struct t10_alua_tg_pt_gp_member),
                        __alignof__(struct t10_alua_tg_pt_gp_member),
                        0, NULL);
        if (!t10_alua_tg_pt_gp_mem_cache) {
                pr_err("kmem_cache_create() for t10_alua_tg_pt_gp_"
                                "mem_t failed\n");
                goto out_free_tg_pt_gp_cache;
        }

        target_completion_wq = alloc_workqueue("target_completion",
                                               WQ_MEM_RECLAIM, 0);
        if (!target_completion_wq)
                goto out_free_tg_pt_gp_mem_cache;

        return 0;

out_free_tg_pt_gp_mem_cache:
        kmem_cache_destroy(t10_alua_tg_pt_gp_mem_cache);
out_free_tg_pt_gp_cache:
        kmem_cache_destroy(t10_alua_tg_pt_gp_cache);
out_free_lu_gp_mem_cache:
        kmem_cache_destroy(t10_alua_lu_gp_mem_cache);
out_free_lu_gp_cache:
        kmem_cache_destroy(t10_alua_lu_gp_cache);
out_free_pr_reg_cache:
        kmem_cache_destroy(t10_pr_reg_cache);
out_free_ua_cache:
        kmem_cache_destroy(se_ua_cache);
out_free_sess_cache:
        kmem_cache_destroy(se_sess_cache);
out:
        return -ENOMEM;
}

void release_se_kmem_caches(void)
{
        destroy_workqueue(target_completion_wq);
        kmem_cache_destroy(se_sess_cache);
        kmem_cache_destroy(se_ua_cache);
        kmem_cache_destroy(t10_pr_reg_cache);
        kmem_cache_destroy(t10_alua_lu_gp_cache);
        kmem_cache_destroy(t10_alua_lu_gp_mem_cache);
        kmem_cache_destroy(t10_alua_tg_pt_gp_cache);
        kmem_cache_destroy(t10_alua_tg_pt_gp_mem_cache);
}

/* This code ensures unique mib indexes are handed out. */
static DEFINE_SPINLOCK(scsi_mib_index_lock);
static u32 scsi_mib_index[SCSI_INDEX_TYPE_MAX];

/*
 * Allocate a new row index for the entry type specified
 */
u32 scsi_get_new_index(scsi_index_t type)
{
        u32 new_index;

        BUG_ON((type < 0) || (type >= SCSI_INDEX_TYPE_MAX));

        spin_lock(&scsi_mib_index_lock);
        new_index = ++scsi_mib_index[type];
        spin_unlock(&scsi_mib_index_lock);

        return new_index;
}

void transport_subsystem_check_init(void)
{
        int ret;
        static int sub_api_initialized;

        if (sub_api_initialized)
                return;

        ret = request_module("target_core_iblock");
        if (ret != 0)
                pr_err("Unable to load target_core_iblock\n");

        ret = request_module("target_core_file");
        if (ret != 0)
                pr_err("Unable to load target_core_file\n");

        ret = request_module("target_core_pscsi");
        if (ret != 0)
                pr_err("Unable to load target_core_pscsi\n");

        sub_api_initialized = 1;
}

struct se_session *transport_init_session(void)
{
        struct se_session *se_sess;

        se_sess = kmem_cache_zalloc(se_sess_cache, GFP_KERNEL);
        if (!se_sess) {
                pr_err("Unable to allocate struct se_session from"
                                " se_sess_cache\n");
                return ERR_PTR(-ENOMEM);
        }
        INIT_LIST_HEAD(&se_sess->sess_list);
        INIT_LIST_HEAD(&se_sess->sess_acl_list);
        INIT_LIST_HEAD(&se_sess->sess_cmd_list);
        spin_lock_init(&se_sess->sess_cmd_lock);
        kref_init(&se_sess->sess_kref);

        return se_sess;
}
EXPORT_SYMBOL(transport_init_session);

/*
 * Called with spin_lock_irqsave(&struct se_portal_group->session_lock called.
 */
void __transport_register_session(
        struct se_portal_group *se_tpg,
        struct se_node_acl *se_nacl,
        struct se_session *se_sess,
        void *fabric_sess_ptr)
{
        unsigned char buf[PR_REG_ISID_LEN];

        se_sess->se_tpg = se_tpg;
        se_sess->fabric_sess_ptr = fabric_sess_ptr;
        /*
         * Used by struct se_node_acl's under ConfigFS to locate active se_session-t
         *
         * Only set for struct se_session's that will actually be moving I/O.
         * eg: *NOT* discovery sessions.
         */
        if (se_nacl) {
                /*
                 * If the fabric module supports an ISID based TransportID,
                 * save this value in binary from the fabric I_T Nexus now.
                 */
                if (se_tpg->se_tpg_tfo->sess_get_initiator_sid != NULL) {
                        memset(&buf[0], 0, PR_REG_ISID_LEN);
                        se_tpg->se_tpg_tfo->sess_get_initiator_sid(se_sess,
                                        &buf[0], PR_REG_ISID_LEN);
                        se_sess->sess_bin_isid = get_unaligned_be64(&buf[0]);
                }
                kref_get(&se_nacl->acl_kref);

                spin_lock_irq(&se_nacl->nacl_sess_lock);
                /*
                 * The se_nacl->nacl_sess pointer will be set to the
                 * last active I_T Nexus for each struct se_node_acl.
                 */
                se_nacl->nacl_sess = se_sess;

                list_add_tail(&se_sess->sess_acl_list,
                              &se_nacl->acl_sess_list);
                spin_unlock_irq(&se_nacl->nacl_sess_lock);
        }
        list_add_tail(&se_sess->sess_list, &se_tpg->tpg_sess_list);

        pr_debug("TARGET_CORE[%s]: Registered fabric_sess_ptr: %p\n",
                se_tpg->se_tpg_tfo->get_fabric_name(), se_sess->fabric_sess_ptr);
}
EXPORT_SYMBOL(__transport_register_session);

void transport_register_session(
        struct se_portal_group *se_tpg,
        struct se_node_acl *se_nacl,
        struct se_session *se_sess,
        void *fabric_sess_ptr)
{
        unsigned long flags;

        spin_lock_irqsave(&se_tpg->session_lock, flags);
        __transport_register_session(se_tpg, se_nacl, se_sess, fabric_sess_ptr);
        spin_unlock_irqrestore(&se_tpg->session_lock, flags);
}
EXPORT_SYMBOL(transport_register_session);

void target_release_session(struct kref *kref)
{
        struct se_session *se_sess = container_of(kref,
                        struct se_session, sess_kref);
        struct se_portal_group *se_tpg = se_sess->se_tpg;

        se_tpg->se_tpg_tfo->close_session(se_sess);
}

void target_get_session(struct se_session *se_sess)
{
        kref_get(&se_sess->sess_kref);
}
EXPORT_SYMBOL(target_get_session);

void target_put_session(struct se_session *se_sess)
{
        struct se_portal_group *tpg = se_sess->se_tpg;

        if (tpg->se_tpg_tfo->put_session != NULL) {
                tpg->se_tpg_tfo->put_session(se_sess);
                return;
        }
        kref_put(&se_sess->sess_kref, target_release_session);
}
EXPORT_SYMBOL(target_put_session);

static void target_complete_nacl(struct kref *kref)
{
        struct se_node_acl *nacl = container_of(kref,
                                struct se_node_acl, acl_kref);

        complete(&nacl->acl_free_comp);
}

void target_put_nacl(struct se_node_acl *nacl)
{
        kref_put(&nacl->acl_kref, target_complete_nacl);
}

void transport_deregister_session_configfs(struct se_session *se_sess)
{
        struct se_node_acl *se_nacl;
        unsigned long flags;
        /*
         * Used by struct se_node_acl's under ConfigFS to locate active struct se_session
         */
        se_nacl = se_sess->se_node_acl;
        if (se_nacl) {
                spin_lock_irqsave(&se_nacl->nacl_sess_lock, flags);
                if (se_nacl->acl_stop == 0)
                        list_del(&se_sess->sess_acl_list);
                /*
                 * If the session list is empty, then clear the pointer.
                 * Otherwise, set the struct se_session pointer from the tail
                 * element of the per struct se_node_acl active session list.
                 */
                if (list_empty(&se_nacl->acl_sess_list))
                        se_nacl->nacl_sess = NULL;
                else {
                        se_nacl->nacl_sess = container_of(
                                        se_nacl->acl_sess_list.prev,
                                        struct se_session, sess_acl_list);
                }
                spin_unlock_irqrestore(&se_nacl->nacl_sess_lock, flags);
        }
}
EXPORT_SYMBOL(transport_deregister_session_configfs);

void transport_free_session(struct se_session *se_sess)
{
        kmem_cache_free(se_sess_cache, se_sess);
}
EXPORT_SYMBOL(transport_free_session);

void transport_deregister_session(struct se_session *se_sess)
{
        struct se_portal_group *se_tpg = se_sess->se_tpg;
        struct target_core_fabric_ops *se_tfo;
        struct se_node_acl *se_nacl;
        unsigned long flags;
        bool comp_nacl = true;

        if (!se_tpg) {
                transport_free_session(se_sess);
                return;
        }
        se_tfo = se_tpg->se_tpg_tfo;

        spin_lock_irqsave(&se_tpg->session_lock, flags);
        list_del(&se_sess->sess_list);
        se_sess->se_tpg = NULL;
        se_sess->fabric_sess_ptr = NULL;
        spin_unlock_irqrestore(&se_tpg->session_lock, flags);

        /*
         * Determine if we need to do extra work for this initiator node's
         * struct se_node_acl if it had been previously dynamically generated.
         */
        se_nacl = se_sess->se_node_acl;

        spin_lock_irqsave(&se_tpg->acl_node_lock, flags);
        if (se_nacl && se_nacl->dynamic_node_acl) {
                if (!se_tfo->tpg_check_demo_mode_cache(se_tpg)) {
                        list_del(&se_nacl->acl_list);
                        se_tpg->num_node_acls--;
                        spin_unlock_irqrestore(&se_tpg->acl_node_lock, flags);
                        core_tpg_wait_for_nacl_pr_ref(se_nacl);
                        core_free_device_list_for_node(se_nacl, se_tpg);
                        se_tfo->tpg_release_fabric_acl(se_tpg, se_nacl);

                        comp_nacl = false;
                        spin_lock_irqsave(&se_tpg->acl_node_lock, flags);
                }
        }
        spin_unlock_irqrestore(&se_tpg->acl_node_lock, flags);

        pr_debug("TARGET_CORE[%s]: Deregistered fabric_sess\n",
                se_tpg->se_tpg_tfo->get_fabric_name());
        /*
         * If last kref is dropping now for an explict NodeACL, awake sleeping
         * ->acl_free_comp caller to wakeup configfs se_node_acl->acl_group
         * removal context.
         */
        if (se_nacl && comp_nacl == true)
                target_put_nacl(se_nacl);

        transport_free_session(se_sess);
}
EXPORT_SYMBOL(transport_deregister_session);

/*
 * Called with cmd->t_state_lock held.
 */
static void target_remove_from_state_list(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        unsigned long flags;

        if (!dev)
                return;

        if (cmd->transport_state & CMD_T_BUSY)
                return;

        spin_lock_irqsave(&dev->execute_task_lock, flags);
        if (cmd->state_active) {
                list_del(&cmd->state_list);
                cmd->state_active = false;
        }
        spin_unlock_irqrestore(&dev->execute_task_lock, flags);
}

static int transport_cmd_check_stop(struct se_cmd *cmd, bool remove_from_lists)
{
        unsigned long flags;

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        /*
         * Determine if IOCTL context caller in requesting the stopping of this
         * command for LUN shutdown purposes.
         */
        if (cmd->transport_state & CMD_T_LUN_STOP) {
                pr_debug("%s:%d CMD_T_LUN_STOP for ITT: 0x%08x\n",
                        __func__, __LINE__, cmd->se_tfo->get_task_tag(cmd));

                cmd->transport_state &= ~CMD_T_ACTIVE;
                if (remove_from_lists)
                        target_remove_from_state_list(cmd);
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);

                complete(&cmd->transport_lun_stop_comp);
                return 1;
        }

        if (remove_from_lists) {
                target_remove_from_state_list(cmd);

                /*
                 * Clear struct se_cmd->se_lun before the handoff to FE.
                 */
                cmd->se_lun = NULL;
        }

        /*
         * Determine if frontend context caller is requesting the stopping of
         * this command for frontend exceptions.
         */
        if (cmd->transport_state & CMD_T_STOP) {
                pr_debug("%s:%d CMD_T_STOP for ITT: 0x%08x\n",
                        __func__, __LINE__,
                        cmd->se_tfo->get_task_tag(cmd));

                spin_unlock_irqrestore(&cmd->t_state_lock, flags);

                complete(&cmd->t_transport_stop_comp);
                return 1;
        }

        cmd->transport_state &= ~CMD_T_ACTIVE;
        if (remove_from_lists) {
                /*
                 * Some fabric modules like tcm_loop can release
                 * their internally allocated I/O reference now and
                 * struct se_cmd now.
                 *
                 * Fabric modules are expected to return '1' here if the
                 * se_cmd being passed is released at this point,
                 * or zero if not being released.
                 */
                if (cmd->se_tfo->check_stop_free != NULL) {
                        spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                        return cmd->se_tfo->check_stop_free(cmd);
                }
        }

        spin_unlock_irqrestore(&cmd->t_state_lock, flags);
        return 0;
}

static int transport_cmd_check_stop_to_fabric(struct se_cmd *cmd)
{
        return transport_cmd_check_stop(cmd, true);
}

static void transport_lun_remove_cmd(struct se_cmd *cmd)
{
        struct se_lun *lun = cmd->se_lun;
        unsigned long flags;

        if (!lun)
                return;

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        if (cmd->transport_state & CMD_T_DEV_ACTIVE) {
                cmd->transport_state &= ~CMD_T_DEV_ACTIVE;
                target_remove_from_state_list(cmd);
        }
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);

        spin_lock_irqsave(&lun->lun_cmd_lock, flags);
        if (!list_empty(&cmd->se_lun_node))
                list_del_init(&cmd->se_lun_node);
        spin_unlock_irqrestore(&lun->lun_cmd_lock, flags);
}

void transport_cmd_finish_abort(struct se_cmd *cmd, int remove)
{
        if (transport_cmd_check_stop_to_fabric(cmd))
                return;
        if (remove)
                transport_put_cmd(cmd);
}

static void target_complete_failure_work(struct work_struct *work)
{
        struct se_cmd *cmd = container_of(work, struct se_cmd, work);

        transport_generic_request_failure(cmd);
}

/*
 * Used when asking transport to copy Sense Data from the underlying
 * Linux/SCSI struct scsi_cmnd
 */
static unsigned char *transport_get_sense_buffer(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;

        WARN_ON(!cmd->se_lun);

        if (!dev)
                return NULL;

        if (cmd->se_cmd_flags & SCF_SENT_CHECK_CONDITION)
                return NULL;

        cmd->scsi_sense_length = TRANSPORT_SENSE_BUFFER;

        pr_debug("HBA_[%u]_PLUG[%s]: Requesting sense for SAM STATUS: 0x%02x\n",
                dev->se_hba->hba_id, dev->transport->name, cmd->scsi_status);
        return cmd->sense_buffer;
}

void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
{
        struct se_device *dev = cmd->se_dev;
        int success = scsi_status == GOOD;
        unsigned long flags;

        cmd->scsi_status = scsi_status;


        spin_lock_irqsave(&cmd->t_state_lock, flags);
        cmd->transport_state &= ~CMD_T_BUSY;

        if (dev && dev->transport->transport_complete) {
                dev->transport->transport_complete(cmd,
                                cmd->t_data_sg,
                                transport_get_sense_buffer(cmd));
                if (cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE)
                        success = 1;
        }

        /*
         * See if we are waiting to complete for an exception condition.
         */
        if (cmd->transport_state & CMD_T_REQUEST_STOP) {
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                complete(&cmd->task_stop_comp);
                return;
        }

        if (!success)
                cmd->transport_state |= CMD_T_FAILED;

        /*
         * Check for case where an explict ABORT_TASK has been received
         * and transport_wait_for_tasks() will be waiting for completion..
         */
        if (cmd->transport_state & CMD_T_ABORTED &&
            cmd->transport_state & CMD_T_STOP) {
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                complete(&cmd->t_transport_stop_comp);
                return;
        } else if (cmd->transport_state & CMD_T_FAILED) {
                cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                INIT_WORK(&cmd->work, target_complete_failure_work);
        } else {
                INIT_WORK(&cmd->work, target_complete_ok_work);
        }

        cmd->t_state = TRANSPORT_COMPLETE;
        cmd->transport_state |= (CMD_T_COMPLETE | CMD_T_ACTIVE);
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);

        queue_work(target_completion_wq, &cmd->work);
}
EXPORT_SYMBOL(target_complete_cmd);

static void target_add_to_state_list(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        unsigned long flags;

        spin_lock_irqsave(&dev->execute_task_lock, flags);
        if (!cmd->state_active) {
                list_add_tail(&cmd->state_list, &dev->state_list);
                cmd->state_active = true;
        }
        spin_unlock_irqrestore(&dev->execute_task_lock, flags);
}

/*
 * Handle QUEUE_FULL / -EAGAIN and -ENOMEM status
 */
static void transport_write_pending_qf(struct se_cmd *cmd);
static void transport_complete_qf(struct se_cmd *cmd);

static void target_qf_do_work(struct work_struct *work)
{
        struct se_device *dev = container_of(work, struct se_device,
                                        qf_work_queue);
        LIST_HEAD(qf_cmd_list);
        struct se_cmd *cmd, *cmd_tmp;

        spin_lock_irq(&dev->qf_cmd_lock);
        list_splice_init(&dev->qf_cmd_list, &qf_cmd_list);
        spin_unlock_irq(&dev->qf_cmd_lock);

        list_for_each_entry_safe(cmd, cmd_tmp, &qf_cmd_list, se_qf_node) {
                list_del(&cmd->se_qf_node);
                atomic_dec(&dev->dev_qf_count);
                smp_mb__after_atomic_dec();

                pr_debug("Processing %s cmd: %p QUEUE_FULL in work queue"
                        " context: %s\n", cmd->se_tfo->get_fabric_name(), cmd,
                        (cmd->t_state == TRANSPORT_COMPLETE_QF_OK) ? "COMPLETE_OK" :
                        (cmd->t_state == TRANSPORT_COMPLETE_QF_WP) ? "WRITE_PENDING"
                        : "UNKNOWN");

                if (cmd->t_state == TRANSPORT_COMPLETE_QF_WP)
                        transport_write_pending_qf(cmd);
                else if (cmd->t_state == TRANSPORT_COMPLETE_QF_OK)
                        transport_complete_qf(cmd);
        }
}

unsigned char *transport_dump_cmd_direction(struct se_cmd *cmd)
{
        switch (cmd->data_direction) {
        case DMA_NONE:
                return "NONE";
        case DMA_FROM_DEVICE:
                return "READ";
        case DMA_TO_DEVICE:
                return "WRITE";
        case DMA_BIDIRECTIONAL:
                return "BIDI";
        default:
                break;
        }

        return "UNKNOWN";
}

void transport_dump_dev_state(
        struct se_device *dev,
        char *b,
        int *bl)
{
        *bl += sprintf(b + *bl, "Status: ");
        switch (dev->dev_status) {
        case TRANSPORT_DEVICE_ACTIVATED:
                *bl += sprintf(b + *bl, "ACTIVATED");
                break;
        case TRANSPORT_DEVICE_DEACTIVATED:
                *bl += sprintf(b + *bl, "DEACTIVATED");
                break;
        case TRANSPORT_DEVICE_SHUTDOWN:
                *bl += sprintf(b + *bl, "SHUTDOWN");
                break;
        case TRANSPORT_DEVICE_OFFLINE_ACTIVATED:
        case TRANSPORT_DEVICE_OFFLINE_DEACTIVATED:
                *bl += sprintf(b + *bl, "OFFLINE");
                break;
        default:
                *bl += sprintf(b + *bl, "UNKNOWN=%d", dev->dev_status);
                break;
        }

        *bl += sprintf(b + *bl, "  Max Queue Depth: %d", dev->queue_depth);
        *bl += sprintf(b + *bl, "  SectorSize: %u  HwMaxSectors: %u\n",
                dev->se_sub_dev->se_dev_attrib.block_size,
                dev->se_sub_dev->se_dev_attrib.hw_max_sectors);
        *bl += sprintf(b + *bl, "        ");
}

void transport_dump_vpd_proto_id(
        struct t10_vpd *vpd,
        unsigned char *p_buf,
        int p_buf_len)
{
        unsigned char buf[VPD_TMP_BUF_SIZE];
        int len;

        memset(buf, 0, VPD_TMP_BUF_SIZE);
        len = sprintf(buf, "T10 VPD Protocol Identifier: ");

        switch (vpd->protocol_identifier) {
        case 0x00:
                sprintf(buf+len, "Fibre Channel\n");
                break;
        case 0x10:
                sprintf(buf+len, "Parallel SCSI\n");
                break;
        case 0x20:
                sprintf(buf+len, "SSA\n");
                break;
        case 0x30:
                sprintf(buf+len, "IEEE 1394\n");
                break;
        case 0x40:
                sprintf(buf+len, "SCSI Remote Direct Memory Access"
                                " Protocol\n");
                break;
        case 0x50:
                sprintf(buf+len, "Internet SCSI (iSCSI)\n");
                break;
        case 0x60:
                sprintf(buf+len, "SAS Serial SCSI Protocol\n");
                break;
        case 0x70:
                sprintf(buf+len, "Automation/Drive Interface Transport"
                                " Protocol\n");
                break;
        case 0x80:
                sprintf(buf+len, "AT Attachment Interface ATA/ATAPI\n");
                break;
        default:
                sprintf(buf+len, "Unknown 0x%02x\n",
                                vpd->protocol_identifier);
                break;
        }

        if (p_buf)
                strncpy(p_buf, buf, p_buf_len);
        else
                pr_debug("%s", buf);
}

void
transport_set_vpd_proto_id(struct t10_vpd *vpd, unsigned char *page_83)
{
        /*
         * Check if the Protocol Identifier Valid (PIV) bit is set..
         *
         * from spc3r23.pdf section 7.5.1
         */
         if (page_83[1] & 0x80) {
                vpd->protocol_identifier = (page_83[0] & 0xf0);
                vpd->protocol_identifier_set = 1;
                transport_dump_vpd_proto_id(vpd, NULL, 0);
        }
}
EXPORT_SYMBOL(transport_set_vpd_proto_id);

int transport_dump_vpd_assoc(
        struct t10_vpd *vpd,
        unsigned char *p_buf,
        int p_buf_len)
{
        unsigned char buf[VPD_TMP_BUF_SIZE];
        int ret = 0;
        int len;

        memset(buf, 0, VPD_TMP_BUF_SIZE);
        len = sprintf(buf, "T10 VPD Identifier Association: ");

        switch (vpd->association) {
        case 0x00:
                sprintf(buf+len, "addressed logical unit\n");
                break;
        case 0x10:
                sprintf(buf+len, "target port\n");
                break;
        case 0x20:
                sprintf(buf+len, "SCSI target device\n");
                break;
        default:
                sprintf(buf+len, "Unknown 0x%02x\n", vpd->association);
                ret = -EINVAL;
                break;
        }

        if (p_buf)
                strncpy(p_buf, buf, p_buf_len);
        else
                pr_debug("%s", buf);

        return ret;
}

int transport_set_vpd_assoc(struct t10_vpd *vpd, unsigned char *page_83)
{
        /*
         * The VPD identification association..
         *
         * from spc3r23.pdf Section 7.6.3.1 Table 297
         */
        vpd->association = (page_83[1] & 0x30);
        return transport_dump_vpd_assoc(vpd, NULL, 0);
}
EXPORT_SYMBOL(transport_set_vpd_assoc);

int transport_dump_vpd_ident_type(
        struct t10_vpd *vpd,
        unsigned char *p_buf,
        int p_buf_len)
{
        unsigned char buf[VPD_TMP_BUF_SIZE];
        int ret = 0;
        int len;

        memset(buf, 0, VPD_TMP_BUF_SIZE);
        len = sprintf(buf, "T10 VPD Identifier Type: ");

        switch (vpd->device_identifier_type) {
        case 0x00:
                sprintf(buf+len, "Vendor specific\n");
                break;
        case 0x01:
                sprintf(buf+len, "T10 Vendor ID based\n");
                break;
        case 0x02:
                sprintf(buf+len, "EUI-64 based\n");
                break;
        case 0x03:
                sprintf(buf+len, "NAA\n");
                break;
        case 0x04:
                sprintf(buf+len, "Relative target port identifier\n");
                break;
        case 0x08:
                sprintf(buf+len, "SCSI name string\n");
                break;
        default:
                sprintf(buf+len, "Unsupported: 0x%02x\n",
                                vpd->device_identifier_type);
                ret = -EINVAL;
                break;
        }

        if (p_buf) {
                if (p_buf_len < strlen(buf)+1)
                        return -EINVAL;
                strncpy(p_buf, buf, p_buf_len);
        } else {
                pr_debug("%s", buf);
        }

        return ret;
}

int transport_set_vpd_ident_type(struct t10_vpd *vpd, unsigned char *page_83)
{
        /*
         * The VPD identifier type..
         *
         * from spc3r23.pdf Section 7.6.3.1 Table 298
         */
        vpd->device_identifier_type = (page_83[1] & 0x0f);
        return transport_dump_vpd_ident_type(vpd, NULL, 0);
}
EXPORT_SYMBOL(transport_set_vpd_ident_type);

int transport_dump_vpd_ident(
        struct t10_vpd *vpd,
        unsigned char *p_buf,
        int p_buf_len)
{
        unsigned char buf[VPD_TMP_BUF_SIZE];
        int ret = 0;

        memset(buf, 0, VPD_TMP_BUF_SIZE);

        switch (vpd->device_identifier_code_set) {
        case 0x01: /* Binary */
                sprintf(buf, "T10 VPD Binary Device Identifier: %s\n",
                        &vpd->device_identifier[0]);
                break;
        case 0x02: /* ASCII */
                sprintf(buf, "T10 VPD ASCII Device Identifier: %s\n",
                        &vpd->device_identifier[0]);
                break;
        case 0x03: /* UTF-8 */
                sprintf(buf, "T10 VPD UTF-8 Device Identifier: %s\n",
                        &vpd->device_identifier[0]);
                break;
        default:
                sprintf(buf, "T10 VPD Device Identifier encoding unsupported:"
                        " 0x%02x", vpd->device_identifier_code_set);
                ret = -EINVAL;
                break;
        }

        if (p_buf)
                strncpy(p_buf, buf, p_buf_len);
        else
                pr_debug("%s", buf);

        return ret;
}

int
transport_set_vpd_ident(struct t10_vpd *vpd, unsigned char *page_83)
{
        static const char hex_str[] = "0123456789abcdef";
        int j = 0, i = 4; /* offset to start of the identifier */

        /*
         * The VPD Code Set (encoding)
         *
         * from spc3r23.pdf Section 7.6.3.1 Table 296
         */
        vpd->device_identifier_code_set = (page_83[0] & 0x0f);
        switch (vpd->device_identifier_code_set) {
        case 0x01: /* Binary */
                vpd->device_identifier[j++] =
                                hex_str[vpd->device_identifier_type];
                while (i < (4 + page_83[3])) {
                        vpd->device_identifier[j++] =
                                hex_str[(page_83[i] & 0xf0) >> 4];
                        vpd->device_identifier[j++] =
                                hex_str[page_83[i] & 0x0f];
                        i++;
                }
                break;
        case 0x02: /* ASCII */
        case 0x03: /* UTF-8 */
                while (i < (4 + page_83[3]))
                        vpd->device_identifier[j++] = page_83[i++];
                break;
        default:
                break;
        }

        return transport_dump_vpd_ident(vpd, NULL, 0);
}
EXPORT_SYMBOL(transport_set_vpd_ident);

static void core_setup_task_attr_emulation(struct se_device *dev)
{
        /*
         * If this device is from Target_Core_Mod/pSCSI, disable the
         * SAM Task Attribute emulation.
         *
         * This is currently not available in upsream Linux/SCSI Target
         * mode code, and is assumed to be disabled while using TCM/pSCSI.
         */
        if (dev->transport->transport_type == TRANSPORT_PLUGIN_PHBA_PDEV) {

                dev->dev_task_attr_type = SAM_TASK_ATTR_PASSTHROUGH;
                return;
        }

        dev->dev_task_attr_type = SAM_TASK_ATTR_EMULATED;
        pr_debug("%s: Using SAM_TASK_ATTR_EMULATED for SPC: 0x%02x"
                " device\n", dev->transport->name,
                dev->transport->get_device_rev(dev));
}

static void scsi_dump_inquiry(struct se_device *dev)
{
        struct t10_wwn *wwn = &dev->se_sub_dev->t10_wwn;
        char buf[17];
        int i, device_type;
        /*
         * Print Linux/SCSI style INQUIRY formatting to the kernel ring buffer
         */
        for (i = 0; i < 8; i++)
                if (wwn->vendor[i] >= 0x20)
                        buf[i] = wwn->vendor[i];
                else
                        buf[i] = ' ';
        buf[i] = '\0';
        pr_debug("  Vendor: %s\n", buf);

        for (i = 0; i < 16; i++)
                if (wwn->model[i] >= 0x20)
                        buf[i] = wwn->model[i];
                else
                        buf[i] = ' ';
        buf[i] = '\0';
        pr_debug("  Model: %s\n", buf);

        for (i = 0; i < 4; i++)
                if (wwn->revision[i] >= 0x20)
                        buf[i] = wwn->revision[i];
                else
                        buf[i] = ' ';
        buf[i] = '\0';
        pr_debug("  Revision: %s\n", buf);

        device_type = dev->transport->get_device_type(dev);
        pr_debug("  Type:   %s ", scsi_device_type(device_type));
        pr_debug("                 ANSI SCSI revision: %02x\n",
                                dev->transport->get_device_rev(dev));
}

struct se_device *transport_add_device_to_core_hba(
        struct se_hba *hba,
        struct se_subsystem_api *transport,
        struct se_subsystem_dev *se_dev,
        u32 device_flags,
        void *transport_dev,
        struct se_dev_limits *dev_limits,
        const char *inquiry_prod,
        const char *inquiry_rev)
{
        int force_pt;
        struct se_device  *dev;

        dev = kzalloc(sizeof(struct se_device), GFP_KERNEL);
        if (!dev) {
                pr_err("Unable to allocate memory for se_dev_t\n");
                return NULL;
        }

        dev->dev_flags          = device_flags;
        dev->dev_status         |= TRANSPORT_DEVICE_DEACTIVATED;
        dev->dev_ptr            = transport_dev;
        dev->se_hba             = hba;
        dev->se_sub_dev         = se_dev;
        dev->transport          = transport;
        dev->dev_link_magic     = SE_DEV_LINK_MAGIC;
        INIT_LIST_HEAD(&dev->dev_list);
        INIT_LIST_HEAD(&dev->dev_sep_list);
        INIT_LIST_HEAD(&dev->dev_tmr_list);
        INIT_LIST_HEAD(&dev->delayed_cmd_list);
        INIT_LIST_HEAD(&dev->state_list);
        INIT_LIST_HEAD(&dev->qf_cmd_list);
        spin_lock_init(&dev->execute_task_lock);
        spin_lock_init(&dev->delayed_cmd_lock);
        spin_lock_init(&dev->dev_reservation_lock);
        spin_lock_init(&dev->dev_status_lock);
        spin_lock_init(&dev->se_port_lock);
        spin_lock_init(&dev->se_tmr_lock);
        spin_lock_init(&dev->qf_cmd_lock);
        atomic_set(&dev->dev_ordered_id, 0);

        se_dev_set_default_attribs(dev, dev_limits);

        dev->dev_index = scsi_get_new_index(SCSI_DEVICE_INDEX);
        dev->creation_time = get_jiffies_64();
        spin_lock_init(&dev->stats_lock);

        spin_lock(&hba->device_lock);
        list_add_tail(&dev->dev_list, &hba->hba_dev_list);
        hba->dev_count++;
        spin_unlock(&hba->device_lock);
        /*
         * Setup the SAM Task Attribute emulation for struct se_device
         */
        core_setup_task_attr_emulation(dev);
        /*
         * Force PR and ALUA passthrough emulation with internal object use.
         */
        force_pt = (hba->hba_flags & HBA_FLAGS_INTERNAL_USE);
        /*
         * Setup the Reservations infrastructure for struct se_device
         */
        core_setup_reservations(dev, force_pt);
        /*
         * Setup the Asymmetric Logical Unit Assignment for struct se_device
         */
        if (core_setup_alua(dev, force_pt) < 0)
                goto err_dev_list;

        /*
         * Startup the struct se_device processing thread
         */
        dev->tmr_wq = alloc_workqueue("tmr-%s", WQ_MEM_RECLAIM | WQ_UNBOUND, 1,
                                      dev->transport->name);
        if (!dev->tmr_wq) {
                pr_err("Unable to create tmr workqueue for %s\n",
                        dev->transport->name);
                goto err_dev_list;
        }
        /*
         * Setup work_queue for QUEUE_FULL
         */
        INIT_WORK(&dev->qf_work_queue, target_qf_do_work);
        /*
         * Preload the initial INQUIRY const values if we are doing
         * anything virtual (IBLOCK, FILEIO, RAMDISK), but not for TCM/pSCSI
         * passthrough because this is being provided by the backend LLD.
         * This is required so that transport_get_inquiry() copies these
         * originals once back into DEV_T10_WWN(dev) for the virtual device
         * setup.
         */
        if (dev->transport->transport_type != TRANSPORT_PLUGIN_PHBA_PDEV) {
                if (!inquiry_prod || !inquiry_rev) {
                        pr_err("All non TCM/pSCSI plugins require"
                                " INQUIRY consts\n");
                        goto err_wq;
                }

                strncpy(&dev->se_sub_dev->t10_wwn.vendor[0], "LIO-ORG", 8);
                strncpy(&dev->se_sub_dev->t10_wwn.model[0], inquiry_prod, 16);
                strncpy(&dev->se_sub_dev->t10_wwn.revision[0], inquiry_rev, 4);
        }
        scsi_dump_inquiry(dev);

        return dev;

err_wq:
        destroy_workqueue(dev->tmr_wq);
err_dev_list:
        spin_lock(&hba->device_lock);
        list_del(&dev->dev_list);
        hba->dev_count--;
        spin_unlock(&hba->device_lock);

        se_release_vpd_for_dev(dev);

        kfree(dev);

        return NULL;
}
EXPORT_SYMBOL(transport_add_device_to_core_hba);

int target_cmd_size_check(struct se_cmd *cmd, unsigned int size)
{
        struct se_device *dev = cmd->se_dev;

        if (cmd->unknown_data_length) {
                cmd->data_length = size;
        } else if (size != cmd->data_length) {
                pr_warn("TARGET_CORE[%s]: Expected Transfer Length:"
                        " %u does not match SCSI CDB Length: %u for SAM Opcode:"
                        " 0x%02x\n", cmd->se_tfo->get_fabric_name(),
                                cmd->data_length, size, cmd->t_task_cdb[0]);

                if (cmd->data_direction == DMA_TO_DEVICE) {
                        pr_err("Rejecting underflow/overflow"
                                        " WRITE data\n");
                        goto out_invalid_cdb_field;
                }
                /*
                 * Reject READ_* or WRITE_* with overflow/underflow for
                 * type SCF_SCSI_DATA_CDB.
                 */
                if (dev->se_sub_dev->se_dev_attrib.block_size != 512)  {
                        pr_err("Failing OVERFLOW/UNDERFLOW for LBA op"
                                " CDB on non 512-byte sector setup subsystem"
                                " plugin: %s\n", dev->transport->name);
                        /* Returns CHECK_CONDITION + INVALID_CDB_FIELD */
                        goto out_invalid_cdb_field;
                }
                /*
                 * For the overflow case keep the existing fabric provided
                 * ->data_length.  Otherwise for the underflow case, reset
                 * ->data_length to the smaller SCSI expected data transfer
                 * length.
                 */
                if (size > cmd->data_length) {
                        cmd->se_cmd_flags |= SCF_OVERFLOW_BIT;
                        cmd->residual_count = (size - cmd->data_length);
                } else {
                        cmd->se_cmd_flags |= SCF_UNDERFLOW_BIT;
                        cmd->residual_count = (cmd->data_length - size);
                        cmd->data_length = size;
                }
        }

        return 0;

out_invalid_cdb_field:
        cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
        cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;
        return -EINVAL;
}

/*
 * Used by fabric modules containing a local struct se_cmd within their
 * fabric dependent per I/O descriptor.
 */
void transport_init_se_cmd(
        struct se_cmd *cmd,
        struct target_core_fabric_ops *tfo,
        struct se_session *se_sess,
        u32 data_length,
        int data_direction,
        int task_attr,
        unsigned char *sense_buffer)
{
        INIT_LIST_HEAD(&cmd->se_lun_node);
        INIT_LIST_HEAD(&cmd->se_delayed_node);
        INIT_LIST_HEAD(&cmd->se_qf_node);
        INIT_LIST_HEAD(&cmd->se_cmd_list);
        INIT_LIST_HEAD(&cmd->state_list);
        init_completion(&cmd->transport_lun_fe_stop_comp);
        init_completion(&cmd->transport_lun_stop_comp);
        init_completion(&cmd->t_transport_stop_comp);
        init_completion(&cmd->cmd_wait_comp);
        init_completion(&cmd->task_stop_comp);
        spin_lock_init(&cmd->t_state_lock);
        cmd->transport_state = CMD_T_DEV_ACTIVE;

        cmd->se_tfo = tfo;
        cmd->se_sess = se_sess;
        cmd->data_length = data_length;
        cmd->data_direction = data_direction;
        cmd->sam_task_attr = task_attr;
        cmd->sense_buffer = sense_buffer;

        cmd->state_active = false;
}
EXPORT_SYMBOL(transport_init_se_cmd);

static int transport_check_alloc_task_attr(struct se_cmd *cmd)
{
        /*
         * Check if SAM Task Attribute emulation is enabled for this
         * struct se_device storage object
         */
        if (cmd->se_dev->dev_task_attr_type != SAM_TASK_ATTR_EMULATED)
                return 0;

        if (cmd->sam_task_attr == MSG_ACA_TAG) {
                pr_debug("SAM Task Attribute ACA"
                        " emulation is not supported\n");
                return -EINVAL;
        }
        /*
         * Used to determine when ORDERED commands should go from
         * Dormant to Active status.
         */
        cmd->se_ordered_id = atomic_inc_return(&cmd->se_dev->dev_ordered_id);
        smp_mb__after_atomic_inc();
        pr_debug("Allocated se_ordered_id: %u for Task Attr: 0x%02x on %s\n",
                        cmd->se_ordered_id, cmd->sam_task_attr,
                        cmd->se_dev->transport->name);
        return 0;
}

/*      target_setup_cmd_from_cdb():
 *
 *      Called from fabric RX Thread.
 */
int target_setup_cmd_from_cdb(
        struct se_cmd *cmd,
        unsigned char *cdb)
{
        struct se_subsystem_dev *su_dev = cmd->se_dev->se_sub_dev;
        u32 pr_reg_type = 0;
        u8 alua_ascq = 0;
        unsigned long flags;
        int ret;

        /*
         * Ensure that the received CDB is less than the max (252 + 8) bytes
         * for VARIABLE_LENGTH_CMD
         */
        if (scsi_command_size(cdb) > SCSI_MAX_VARLEN_CDB_SIZE) {
                pr_err("Received SCSI CDB with command_size: %d that"
                        " exceeds SCSI_MAX_VARLEN_CDB_SIZE: %d\n",
                        scsi_command_size(cdb), SCSI_MAX_VARLEN_CDB_SIZE);
                cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
                cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;
                return -EINVAL;
        }
        /*
         * If the received CDB is larger than TCM_MAX_COMMAND_SIZE,
         * allocate the additional extended CDB buffer now..  Otherwise
         * setup the pointer from __t_task_cdb to t_task_cdb.
         */
        if (scsi_command_size(cdb) > sizeof(cmd->__t_task_cdb)) {
                cmd->t_task_cdb = kzalloc(scsi_command_size(cdb),
                                                GFP_KERNEL);
                if (!cmd->t_task_cdb) {
                        pr_err("Unable to allocate cmd->t_task_cdb"
                                " %u > sizeof(cmd->__t_task_cdb): %lu ops\n",
                                scsi_command_size(cdb),
                                (unsigned long)sizeof(cmd->__t_task_cdb));
                        cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
                        cmd->scsi_sense_reason =
                                        TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                        return -ENOMEM;
                }
        } else
                cmd->t_task_cdb = &cmd->__t_task_cdb[0];
        /*
         * Copy the original CDB into cmd->
         */
        memcpy(cmd->t_task_cdb, cdb, scsi_command_size(cdb));

        /*
         * Check for an existing UNIT ATTENTION condition
         */
        if (core_scsi3_ua_check(cmd, cdb) < 0) {
                cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
                cmd->scsi_sense_reason = TCM_CHECK_CONDITION_UNIT_ATTENTION;
                return -EINVAL;
        }

        ret = su_dev->t10_alua.alua_state_check(cmd, cdb, &alua_ascq);
        if (ret != 0) {
                /*
                 * Set SCSI additional sense code (ASC) to 'LUN Not Accessible';
                 * The ALUA additional sense code qualifier (ASCQ) is determined
                 * by the ALUA primary or secondary access state..
                 */
                if (ret > 0) {
                        pr_debug("[%s]: ALUA TG Port not available, "
                                "SenseKey: NOT_READY, ASC/ASCQ: "
                                "0x04/0x%02x\n",
                                cmd->se_tfo->get_fabric_name(), alua_ascq);

                        transport_set_sense_codes(cmd, 0x04, alua_ascq);
                        cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
                        cmd->scsi_sense_reason = TCM_CHECK_CONDITION_NOT_READY;
                        return -EINVAL;
                }
                cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
                cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;
                return -EINVAL;
        }

        /*
         * Check status for SPC-3 Persistent Reservations
         */
        if (su_dev->t10_pr.pr_ops.t10_reservation_check(cmd, &pr_reg_type)) {
                if (su_dev->t10_pr.pr_ops.t10_seq_non_holder(
                                        cmd, cdb, pr_reg_type) != 0) {
                        cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
                        cmd->se_cmd_flags |= SCF_SCSI_RESERVATION_CONFLICT;
                        cmd->scsi_status = SAM_STAT_RESERVATION_CONFLICT;
                        cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
                        return -EBUSY;
                }
                /*
                 * This means the CDB is allowed for the SCSI Initiator port
                 * when said port is *NOT* holding the legacy SPC-2 or
                 * SPC-3 Persistent Reservation.
                 */
        }

        ret = cmd->se_dev->transport->parse_cdb(cmd);
        if (ret < 0)
                return ret;

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        cmd->se_cmd_flags |= SCF_SUPPORTED_SAM_OPCODE;
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);

        /*
         * Check for SAM Task Attribute Emulation
         */
        if (transport_check_alloc_task_attr(cmd) < 0) {
                cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
                cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;
                return -EINVAL;
        }
        spin_lock(&cmd->se_lun->lun_sep_lock);
        if (cmd->se_lun->lun_sep)
                cmd->se_lun->lun_sep->sep_stats.cmd_pdus++;
        spin_unlock(&cmd->se_lun->lun_sep_lock);
        return 0;
}
EXPORT_SYMBOL(target_setup_cmd_from_cdb);

/*
 * Used by fabric module frontends to queue tasks directly.
 * Many only be used from process context only
 */
int transport_handle_cdb_direct(
        struct se_cmd *cmd)
{
        int ret;

        if (!cmd->se_lun) {
                dump_stack();
                pr_err("cmd->se_lun is NULL\n");
                return -EINVAL;
        }
        if (in_interrupt()) {
                dump_stack();
                pr_err("transport_generic_handle_cdb cannot be called"
                                " from interrupt context\n");
                return -EINVAL;
        }
        /*
         * Set TRANSPORT_NEW_CMD state and CMD_T_ACTIVE to ensure that
         * outstanding descriptors are handled correctly during shutdown via
         * transport_wait_for_tasks()
         *
         * Also, we don't take cmd->t_state_lock here as we only expect
         * this to be called for initial descriptor submission.
         */
        cmd->t_state = TRANSPORT_NEW_CMD;
        cmd->transport_state |= CMD_T_ACTIVE;

        /*
         * transport_generic_new_cmd() is already handling QUEUE_FULL,
         * so follow TRANSPORT_NEW_CMD processing thread context usage
         * and call transport_generic_request_failure() if necessary..
         */
        ret = transport_generic_new_cmd(cmd);
        if (ret < 0)
                transport_generic_request_failure(cmd);

        return 0;
}
EXPORT_SYMBOL(transport_handle_cdb_direct);

/*
 * target_submit_cmd_map_sgls - lookup unpacked lun and submit uninitialized
 *                       se_cmd + use pre-allocated SGL memory.
 *
 * @se_cmd: command descriptor to submit
 * @se_sess: associated se_sess for endpoint
 * @cdb: pointer to SCSI CDB
 * @sense: pointer to SCSI sense buffer
 * @unpacked_lun: unpacked LUN to reference for struct se_lun
 * @data_length: fabric expected data transfer length
 * @task_addr: SAM task attribute
 * @data_dir: DMA data direction
 * @flags: flags for command submission from target_sc_flags_tables
 * @sgl: struct scatterlist memory for unidirectional mapping
 * @sgl_count: scatterlist count for unidirectional mapping
 * @sgl_bidi: struct scatterlist memory for bidirectional READ mapping
 * @sgl_bidi_count: scatterlist count for bidirectional READ mapping
 *
 * Returns non zero to signal active I/O shutdown failure.  All other
 * setup exceptions will be returned as a SCSI CHECK_CONDITION response,
 * but still return zero here.
 *
 * This may only be called from process context, and also currently
 * assumes internal allocation of fabric payload buffer by target-core.
 */
int target_submit_cmd_map_sgls(struct se_cmd *se_cmd, struct se_session *se_sess,
                unsigned char *cdb, unsigned char *sense, u32 unpacked_lun,
                u32 data_length, int task_attr, int data_dir, int flags,
                struct scatterlist *sgl, u32 sgl_count,
                struct scatterlist *sgl_bidi, u32 sgl_bidi_count)
{
        struct se_portal_group *se_tpg;
        int rc;

        se_tpg = se_sess->se_tpg;
        BUG_ON(!se_tpg);
        BUG_ON(se_cmd->se_tfo || se_cmd->se_sess);
        BUG_ON(in_interrupt());
        /*
         * Initialize se_cmd for target operation.  From this point
         * exceptions are handled by sending exception status via
         * target_core_fabric_ops->queue_status() callback
         */
        transport_init_se_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess,
                                data_length, data_dir, task_attr, sense);
        if (flags & TARGET_SCF_UNKNOWN_SIZE)
                se_cmd->unknown_data_length = 1;
        /*
         * Obtain struct se_cmd->cmd_kref reference and add new cmd to
         * se_sess->sess_cmd_list.  A second kref_get here is necessary
         * for fabrics using TARGET_SCF_ACK_KREF that expect a second
         * kref_put() to happen during fabric packet acknowledgement.
         */
        rc = target_get_sess_cmd(se_sess, se_cmd, (flags & TARGET_SCF_ACK_KREF));
        if (rc)
                return rc;
        /*
         * Signal bidirectional data payloads to target-core
         */
        if (flags & TARGET_SCF_BIDI_OP)
                se_cmd->se_cmd_flags |= SCF_BIDI;
        /*
         * Locate se_lun pointer and attach it to struct se_cmd
         */
        if (transport_lookup_cmd_lun(se_cmd, unpacked_lun) < 0) {
                transport_send_check_condition_and_sense(se_cmd,
                                se_cmd->scsi_sense_reason, 0);
                target_put_sess_cmd(se_sess, se_cmd);
                return 0;
        }

        rc = target_setup_cmd_from_cdb(se_cmd, cdb);
        if (rc != 0) {
                transport_generic_request_failure(se_cmd);
                return 0;
        }
        /*
         * When a non zero sgl_count has been passed perform SGL passthrough
         * mapping for pre-allocated fabric memory instead of having target
         * core perform an internal SGL allocation..
         */
        if (sgl_count != 0) {
                BUG_ON(!sgl);

                /*
                 * A work-around for tcm_loop as some userspace code via
                 * scsi-generic do not memset their associated read buffers,
                 * so go ahead and do that here for type non-data CDBs.  Also
                 * note that this is currently guaranteed to be a single SGL
                 * for this case by target core in target_setup_cmd_from_cdb()
                 * -> transport_generic_cmd_sequencer().
                 */
                if (!(se_cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) &&
                     se_cmd->data_direction == DMA_FROM_DEVICE) {
                        unsigned char *buf = NULL;

                        if (sgl)
                                buf = kmap(sg_page(sgl)) + sgl->offset;

                        if (buf) {
                                memset(buf, 0, sgl->length);
                                kunmap(sg_page(sgl));
                        }
                }

                rc = transport_generic_map_mem_to_cmd(se_cmd, sgl, sgl_count,
                                sgl_bidi, sgl_bidi_count);
                if (rc != 0) {
                        transport_generic_request_failure(se_cmd);
                        return 0;
                }
        }
        /*
         * Check if we need to delay processing because of ALUA
         * Active/NonOptimized primary access state..
         */
        core_alua_check_nonop_delay(se_cmd);

        transport_handle_cdb_direct(se_cmd);
        return 0;
}
EXPORT_SYMBOL(target_submit_cmd_map_sgls);

/*
 * target_submit_cmd - lookup unpacked lun and submit uninitialized se_cmd
 *
 * @se_cmd: command descriptor to submit
 * @se_sess: associated se_sess for endpoint
 * @cdb: pointer to SCSI CDB
 * @sense: pointer to SCSI sense buffer
 * @unpacked_lun: unpacked LUN to reference for struct se_lun
 * @data_length: fabric expected data transfer length
 * @task_addr: SAM task attribute
 * @data_dir: DMA data direction
 * @flags: flags for command submission from target_sc_flags_tables
 *
 * Returns non zero to signal active I/O shutdown failure.  All other
 * setup exceptions will be returned as a SCSI CHECK_CONDITION response,
 * but still return zero here.
 *
 * This may only be called from process context, and also currently
 * assumes internal allocation of fabric payload buffer by target-core.
 *
 * It also assumes interal target core SGL memory allocation.
 */
int target_submit_cmd(struct se_cmd *se_cmd, struct se_session *se_sess,
                unsigned char *cdb, unsigned char *sense, u32 unpacked_lun,
                u32 data_length, int task_attr, int data_dir, int flags)
{
        return target_submit_cmd_map_sgls(se_cmd, se_sess, cdb, sense,
                        unpacked_lun, data_length, task_attr, data_dir,
                        flags, NULL, 0, NULL, 0);
}
EXPORT_SYMBOL(target_submit_cmd);

static void target_complete_tmr_failure(struct work_struct *work)
{
        struct se_cmd *se_cmd = container_of(work, struct se_cmd, work);

        se_cmd->se_tmr_req->response = TMR_LUN_DOES_NOT_EXIST;
        se_cmd->se_tfo->queue_tm_rsp(se_cmd);

        transport_cmd_check_stop_to_fabric(se_cmd);
}

/**
 * target_submit_tmr - lookup unpacked lun and submit uninitialized se_cmd
 *                     for TMR CDBs
 *
 * @se_cmd: command descriptor to submit
 * @se_sess: associated se_sess for endpoint
 * @sense: pointer to SCSI sense buffer
 * @unpacked_lun: unpacked LUN to reference for struct se_lun
 * @fabric_context: fabric context for TMR req
 * @tm_type: Type of TM request
 * @gfp: gfp type for caller
 * @tag: referenced task tag for TMR_ABORT_TASK
 * @flags: submit cmd flags
 *
 * Callable from all contexts.
 **/

int target_submit_tmr(struct se_cmd *se_cmd, struct se_session *se_sess,
                unsigned char *sense, u32 unpacked_lun,
                void *fabric_tmr_ptr, unsigned char tm_type,
                gfp_t gfp, unsigned int tag, int flags)
{
        struct se_portal_group *se_tpg;
        int ret;

        se_tpg = se_sess->se_tpg;
        BUG_ON(!se_tpg);

        transport_init_se_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess,
                              0, DMA_NONE, MSG_SIMPLE_TAG, sense);
        /*
         * FIXME: Currently expect caller to handle se_cmd->se_tmr_req
         * allocation failure.
         */
        ret = core_tmr_alloc_req(se_cmd, fabric_tmr_ptr, tm_type, gfp);
        if (ret < 0)
                return -ENOMEM;

        if (tm_type == TMR_ABORT_TASK)
                se_cmd->se_tmr_req->ref_task_tag = tag;

        /* See target_submit_cmd for commentary */
        ret = target_get_sess_cmd(se_sess, se_cmd, (flags & TARGET_SCF_ACK_KREF));
        if (ret) {
                core_tmr_release_req(se_cmd->se_tmr_req);
                return ret;
        }

        ret = transport_lookup_tmr_lun(se_cmd, unpacked_lun);
        if (ret) {
                /*
                 * For callback during failure handling, push this work off
                 * to process context with TMR_LUN_DOES_NOT_EXIST status.
                 */
                INIT_WORK(&se_cmd->work, target_complete_tmr_failure);
                schedule_work(&se_cmd->work);
                return 0;
        }
        transport_generic_handle_tmr(se_cmd);
        return 0;
}
EXPORT_SYMBOL(target_submit_tmr);

/*
 * If the cmd is active, request it to be stopped and sleep until it
 * has completed.
 */
bool target_stop_cmd(struct se_cmd *cmd, unsigned long *flags)
{
        bool was_active = false;

        if (cmd->transport_state & CMD_T_BUSY) {
                cmd->transport_state |= CMD_T_REQUEST_STOP;
                spin_unlock_irqrestore(&cmd->t_state_lock, *flags);

                pr_debug("cmd %p waiting to complete\n", cmd);
                wait_for_completion(&cmd->task_stop_comp);
                pr_debug("cmd %p stopped successfully\n", cmd);

                spin_lock_irqsave(&cmd->t_state_lock, *flags);
                cmd->transport_state &= ~CMD_T_REQUEST_STOP;
                cmd->transport_state &= ~CMD_T_BUSY;
                was_active = true;
        }

        return was_active;
}

/*
 * Handle SAM-esque emulation for generic transport request failures.
 */
void transport_generic_request_failure(struct se_cmd *cmd)
{
        int ret = 0;

        pr_debug("-----[ Storage Engine Exception for cmd: %p ITT: 0x%08x"
                " CDB: 0x%02x\n", cmd, cmd->se_tfo->get_task_tag(cmd),
                cmd->t_task_cdb[0]);
        pr_debug("-----[ i_state: %d t_state: %d scsi_sense_reason: %d\n",
                cmd->se_tfo->get_cmd_state(cmd),
                cmd->t_state, cmd->scsi_sense_reason);
        pr_debug("-----[ CMD_T_ACTIVE: %d CMD_T_STOP: %d CMD_T_SENT: %d\n",
                (cmd->transport_state & CMD_T_ACTIVE) != 0,
                (cmd->transport_state & CMD_T_STOP) != 0,
                (cmd->transport_state & CMD_T_SENT) != 0);

        /*
         * For SAM Task Attribute emulation for failed struct se_cmd
         */
        if (cmd->se_dev->dev_task_attr_type == SAM_TASK_ATTR_EMULATED)
                transport_complete_task_attr(cmd);

        switch (cmd->scsi_sense_reason) {
        case TCM_NON_EXISTENT_LUN:
        case TCM_UNSUPPORTED_SCSI_OPCODE:
        case TCM_INVALID_CDB_FIELD:
        case TCM_INVALID_PARAMETER_LIST:
        case TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE:
        case TCM_UNKNOWN_MODE_PAGE:
        case TCM_WRITE_PROTECTED:
        case TCM_ADDRESS_OUT_OF_RANGE:
        case TCM_CHECK_CONDITION_ABORT_CMD:
        case TCM_CHECK_CONDITION_UNIT_ATTENTION:
        case TCM_CHECK_CONDITION_NOT_READY:
                break;
        case TCM_RESERVATION_CONFLICT:
                /*
                 * No SENSE Data payload for this case, set SCSI Status
                 * and queue the response to $FABRIC_MOD.
                 *
                 * Uses linux/include/scsi/scsi.h SAM status codes defs
                 */
                cmd->scsi_status = SAM_STAT_RESERVATION_CONFLICT;
                /*
                 * For UA Interlock Code 11b, a RESERVATION CONFLICT will
                 * establish a UNIT ATTENTION with PREVIOUS RESERVATION
                 * CONFLICT STATUS.
                 *
                 * See spc4r17, section 7.4.6 Control Mode Page, Table 349
                 */
                if (cmd->se_sess &&
                    cmd->se_dev->se_sub_dev->se_dev_attrib.emulate_ua_intlck_ctrl == 2)
                        core_scsi3_ua_allocate(cmd->se_sess->se_node_acl,
                                cmd->orig_fe_lun, 0x2C,
                                ASCQ_2CH_PREVIOUS_RESERVATION_CONFLICT_STATUS);

                ret = cmd->se_tfo->queue_status(cmd);
                if (ret == -EAGAIN || ret == -ENOMEM)
                        goto queue_full;
                goto check_stop;
        default:
                pr_err("Unknown transport error for CDB 0x%02x: %d\n",
                        cmd->t_task_cdb[0], cmd->scsi_sense_reason);
                cmd->scsi_sense_reason = TCM_UNSUPPORTED_SCSI_OPCODE;
                break;
        }

        ret = transport_send_check_condition_and_sense(cmd,
                        cmd->scsi_sense_reason, 0);
        if (ret == -EAGAIN || ret == -ENOMEM)
                goto queue_full;

check_stop:
        transport_lun_remove_cmd(cmd);
        if (!transport_cmd_check_stop_to_fabric(cmd))
                ;
        return;

queue_full:
        cmd->t_state = TRANSPORT_COMPLETE_QF_OK;
        transport_handle_queue_full(cmd, cmd->se_dev);
}
EXPORT_SYMBOL(transport_generic_request_failure);

static void __target_execute_cmd(struct se_cmd *cmd)
{
        int error = 0;

        spin_lock_irq(&cmd->t_state_lock);
        cmd->transport_state |= (CMD_T_BUSY|CMD_T_SENT);
        spin_unlock_irq(&cmd->t_state_lock);

        if (cmd->execute_cmd)
                error = cmd->execute_cmd(cmd);

        if (error) {
                spin_lock_irq(&cmd->t_state_lock);
                cmd->transport_state &= ~(CMD_T_BUSY|CMD_T_SENT);
                spin_unlock_irq(&cmd->t_state_lock);

                transport_generic_request_failure(cmd);
        }
}

void target_execute_cmd(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;

        /*
         * If the received CDB has aleady been aborted stop processing it here.
         */
        if (transport_check_aborted_status(cmd, 1)) {
                complete(&cmd->t_transport_stop_comp);
                return;
        }

        /*
         * Determine if IOCTL context caller in requesting the stopping of this
         * command for LUN shutdown purposes.
         */
        spin_lock_irq(&cmd->t_state_lock);
        if (cmd->transport_state & CMD_T_LUN_STOP) {
                pr_debug("%s:%d CMD_T_LUN_STOP for ITT: 0x%08x\n",
                        __func__, __LINE__, cmd->se_tfo->get_task_tag(cmd));

                cmd->transport_state &= ~CMD_T_ACTIVE;
                spin_unlock_irq(&cmd->t_state_lock);
                complete(&cmd->transport_lun_stop_comp);
                return;
        }
        /*
         * Determine if frontend context caller is requesting the stopping of
         * this command for frontend exceptions.
         */
        if (cmd->transport_state & CMD_T_STOP) {
                pr_debug("%s:%d CMD_T_STOP for ITT: 0x%08x\n",
                        __func__, __LINE__,
                        cmd->se_tfo->get_task_tag(cmd));

                spin_unlock_irq(&cmd->t_state_lock);
                complete(&cmd->t_transport_stop_comp);
                return;
        }

        cmd->t_state = TRANSPORT_PROCESSING;
        cmd->transport_state |= CMD_T_ACTIVE;
        spin_unlock_irq(&cmd->t_state_lock);

        if (dev->dev_task_attr_type != SAM_TASK_ATTR_EMULATED)
                goto execute;

        /*
         * Check for the existence of HEAD_OF_QUEUE, and if true return 1
         * to allow the passed struct se_cmd list of tasks to the front of the list.
         */
        switch (cmd->sam_task_attr) {
        case MSG_HEAD_TAG:
                pr_debug("Added HEAD_OF_QUEUE for CDB: 0x%02x, "
                         "se_ordered_id: %u\n",
                         cmd->t_task_cdb[0], cmd->se_ordered_id);
                goto execute;
        case MSG_ORDERED_TAG:
                atomic_inc(&dev->dev_ordered_sync);
                smp_mb__after_atomic_inc();

                pr_debug("Added ORDERED for CDB: 0x%02x to ordered list, "
                         " se_ordered_id: %u\n",
                         cmd->t_task_cdb[0], cmd->se_ordered_id);

                /*
                 * Execute an ORDERED command if no other older commands
                 * exist that need to be completed first.
                 */
                if (!atomic_read(&dev->simple_cmds))
                        goto execute;
                break;
        default:
                /*
                 * For SIMPLE and UNTAGGED Task Attribute commands
                 */
                atomic_inc(&dev->simple_cmds);
                smp_mb__after_atomic_inc();
                break;
        }

        if (atomic_read(&dev->dev_ordered_sync) != 0) {
                spin_lock(&dev->delayed_cmd_lock);
                list_add_tail(&cmd->se_delayed_node, &dev->delayed_cmd_list);
                spin_unlock(&dev->delayed_cmd_lock);

                pr_debug("Added CDB: 0x%02x Task Attr: 0x%02x to"
                        " delayed CMD list, se_ordered_id: %u\n",
                        cmd->t_task_cdb[0], cmd->sam_task_attr,
                        cmd->se_ordered_id);
                return;
        }

execute:
        /*
         * Otherwise, no ORDERED task attributes exist..
         */
        __target_execute_cmd(cmd);
}
EXPORT_SYMBOL(target_execute_cmd);

/*
 * Process all commands up to the last received ORDERED task attribute which
 * requires another blocking boundary
 */
static void target_restart_delayed_cmds(struct se_device *dev)
{
        for (;;) {
                struct se_cmd *cmd;

                spin_lock(&dev->delayed_cmd_lock);
                if (list_empty(&dev->delayed_cmd_list)) {
                        spin_unlock(&dev->delayed_cmd_lock);
                        break;
                }

                cmd = list_entry(dev->delayed_cmd_list.next,
                                 struct se_cmd, se_delayed_node);
                list_del(&cmd->se_delayed_node);
                spin_unlock(&dev->delayed_cmd_lock);

                __target_execute_cmd(cmd);

                if (cmd->sam_task_attr == MSG_ORDERED_TAG)
                        break;
        }
}

/*
 * Called from I/O completion to determine which dormant/delayed
 * and ordered cmds need to have their tasks added to the execution queue.
 */
static void transport_complete_task_attr(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;

        if (cmd->sam_task_attr == MSG_SIMPLE_TAG) {
                atomic_dec(&dev->simple_cmds);
                smp_mb__after_atomic_dec();
                dev->dev_cur_ordered_id++;
                pr_debug("Incremented dev->dev_cur_ordered_id: %u for"
                        " SIMPLE: %u\n", dev->dev_cur_ordered_id,
                        cmd->se_ordered_id);
        } else if (cmd->sam_task_attr == MSG_HEAD_TAG) {
                dev->dev_cur_ordered_id++;
                pr_debug("Incremented dev_cur_ordered_id: %u for"
                        " HEAD_OF_QUEUE: %u\n", dev->dev_cur_ordered_id,
                        cmd->se_ordered_id);
        } else if (cmd->sam_task_attr == MSG_ORDERED_TAG) {
                atomic_dec(&dev->dev_ordered_sync);
                smp_mb__after_atomic_dec();

                dev->dev_cur_ordered_id++;
                pr_debug("Incremented dev_cur_ordered_id: %u for ORDERED:"
                        " %u\n", dev->dev_cur_ordered_id, cmd->se_ordered_id);
        }

        target_restart_delayed_cmds(dev);
}

static void transport_complete_qf(struct se_cmd *cmd)
{
        int ret = 0;

        if (cmd->se_dev->dev_task_attr_type == SAM_TASK_ATTR_EMULATED)
                transport_complete_task_attr(cmd);

        if (cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) {
                ret = cmd->se_tfo->queue_status(cmd);
                if (ret)
                        goto out;
        }

        switch (cmd->data_direction) {
        case DMA_FROM_DEVICE:
                ret = cmd->se_tfo->queue_data_in(cmd);
                break;
        case DMA_TO_DEVICE:
                if (cmd->t_bidi_data_sg) {
                        ret = cmd->se_tfo->queue_data_in(cmd);
                        if (ret < 0)
                                break;
                }
                /* Fall through for DMA_TO_DEVICE */
        case DMA_NONE:
                ret = cmd->se_tfo->queue_status(cmd);

                break;
        default:
                break;
        }

out:
        if (ret < 0) {
                transport_handle_queue_full(cmd, cmd->se_dev);
                return;
        }
        transport_lun_remove_cmd(cmd);
        transport_cmd_check_stop_to_fabric(cmd);
}

static void transport_handle_queue_full(
        struct se_cmd *cmd,
        struct se_device *dev)
{
        spin_lock_irq(&dev->qf_cmd_lock);
        list_add_tail(&cmd->se_qf_node, &cmd->se_dev->qf_cmd_list);
        atomic_inc(&dev->dev_qf_count);
        smp_mb__after_atomic_inc();
        spin_unlock_irq(&cmd->se_dev->qf_cmd_lock);

        schedule_work(&cmd->se_dev->qf_work_queue);
}

static void target_complete_ok_work(struct work_struct *work)
{
        struct se_cmd *cmd = container_of(work, struct se_cmd, work);
        int ret;

        /*
         * Check if we need to move delayed/dormant tasks from cmds on the
         * delayed execution list after a HEAD_OF_QUEUE or ORDERED Task
         * Attribute.
         */
        if (cmd->se_dev->dev_task_attr_type == SAM_TASK_ATTR_EMULATED)
                transport_complete_task_attr(cmd);
        /*
         * Check to schedule QUEUE_FULL work, or execute an existing
         * cmd->transport_qf_callback()
         */
        if (atomic_read(&cmd->se_dev->dev_qf_count) != 0)
                schedule_work(&cmd->se_dev->qf_work_queue);

        /*
         * Check if we need to send a sense buffer from
         * the struct se_cmd in question.
         */
        if (cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) {
                WARN_ON(!cmd->scsi_status);
                ret = transport_send_check_condition_and_sense(
                                        cmd, 0, 1);
                if (ret == -EAGAIN || ret == -ENOMEM)
                        goto queue_full;

                transport_lun_remove_cmd(cmd);
                transport_cmd_check_stop_to_fabric(cmd);
                return;
        }
        /*
         * Check for a callback, used by amongst other things
         * XDWRITE_READ_10 emulation.
         */
        if (cmd->transport_complete_callback)
                cmd->transport_complete_callback(cmd);

        switch (cmd->data_direction) {
        case DMA_FROM_DEVICE:
                spin_lock(&cmd->se_lun->lun_sep_lock);
                if (cmd->se_lun->lun_sep) {
                        cmd->se_lun->lun_sep->sep_stats.tx_data_octets +=
                                        cmd->data_length;
                }
                spin_unlock(&cmd->se_lun->lun_sep_lock);

                ret = cmd->se_tfo->queue_data_in(cmd);
                if (ret == -EAGAIN || ret == -ENOMEM)
                        goto queue_full;
                break;
        case DMA_TO_DEVICE:
                spin_lock(&cmd->se_lun->lun_sep_lock);
                if (cmd->se_lun->lun_sep) {
                        cmd->se_lun->lun_sep->sep_stats.rx_data_octets +=
                                cmd->data_length;
                }
                spin_unlock(&cmd->se_lun->lun_sep_lock);
                /*
                 * Check if we need to send READ payload for BIDI-COMMAND
                 */
                if (cmd->t_bidi_data_sg) {
                        spin_lock(&cmd->se_lun->lun_sep_lock);
                        if (cmd->se_lun->lun_sep) {
                                cmd->se_lun->lun_sep->sep_stats.tx_data_octets +=
                                        cmd->data_length;
                        }
                        spin_unlock(&cmd->se_lun->lun_sep_lock);
                        ret = cmd->se_tfo->queue_data_in(cmd);
                        if (ret == -EAGAIN || ret == -ENOMEM)
                                goto queue_full;
                        break;
                }
                /* Fall through for DMA_TO_DEVICE */
        case DMA_NONE:
                ret = cmd->se_tfo->queue_status(cmd);
                if (ret == -EAGAIN || ret == -ENOMEM)
                        goto queue_full;
                break;
        default:
                break;
        }

        transport_lun_remove_cmd(cmd);
        transport_cmd_check_stop_to_fabric(cmd);
        return;

queue_full:
        pr_debug("Handling complete_ok QUEUE_FULL: se_cmd: %p,"
                " data_direction: %d\n", cmd, cmd->data_direction);
        cmd->t_state = TRANSPORT_COMPLETE_QF_OK;
        transport_handle_queue_full(cmd, cmd->se_dev);
}

static inline void transport_free_sgl(struct scatterlist *sgl, int nents)
{
        struct scatterlist *sg;
        int count;

        for_each_sg(sgl, sg, nents, count)
                __free_page(sg_page(sg));

        kfree(sgl);
}

static inline void transport_free_pages(struct se_cmd *cmd)
{
        if (cmd->se_cmd_flags & SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC)
                return;

        transport_free_sgl(cmd->t_data_sg, cmd->t_data_nents);
        cmd->t_data_sg = NULL;
        cmd->t_data_nents = 0;

        transport_free_sgl(cmd->t_bidi_data_sg, cmd->t_bidi_data_nents);
        cmd->t_bidi_data_sg = NULL;
        cmd->t_bidi_data_nents = 0;
}

/**
 * transport_release_cmd - free a command
 * @cmd:       command to free
 *
 * This routine unconditionally frees a command, and reference counting
 * or list removal must be done in the caller.
 */
static void transport_release_cmd(struct se_cmd *cmd)
{
        BUG_ON(!cmd->se_tfo);

        if (cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)
                core_tmr_release_req(cmd->se_tmr_req);
        if (cmd->t_task_cdb != cmd->__t_task_cdb)
                kfree(cmd->t_task_cdb);
        /*
         * If this cmd has been setup with target_get_sess_cmd(), drop
         * the kref and call ->release_cmd() in kref callback.
         */
         if (cmd->check_release != 0) {
                target_put_sess_cmd(cmd->se_sess, cmd);
                return;
        }
        cmd->se_tfo->release_cmd(cmd);
}

/**
 * transport_put_cmd - release a reference to a command
 * @cmd:       command to release
 *
 * This routine releases our reference to the command and frees it if possible.
 */
static void transport_put_cmd(struct se_cmd *cmd)
{
        unsigned long flags;

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        if (atomic_read(&cmd->t_fe_count)) {
                if (!atomic_dec_and_test(&cmd->t_fe_count))
                        goto out_busy;
        }

        if (cmd->transport_state & CMD_T_DEV_ACTIVE) {
                cmd->transport_state &= ~CMD_T_DEV_ACTIVE;
                target_remove_from_state_list(cmd);
        }
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);

        transport_free_pages(cmd);
        transport_release_cmd(cmd);
        return;
out_busy:
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);
}

/*
 * transport_generic_map_mem_to_cmd - Use fabric-alloced pages instead of
 * allocating in the core.
 * @cmd:  Associated se_cmd descriptor
 * @mem:  SGL style memory for TCM WRITE / READ
 * @sg_mem_num: Number of SGL elements
 * @mem_bidi_in: SGL style memory for TCM BIDI READ
 * @sg_mem_bidi_num: Number of BIDI READ SGL elements
 *
 * Return: nonzero return cmd was rejected for -ENOMEM or inproper usage
 * of parameters.
 */
int transport_generic_map_mem_to_cmd(
        struct se_cmd *cmd,
        struct scatterlist *sgl,
        u32 sgl_count,
        struct scatterlist *sgl_bidi,
        u32 sgl_bidi_count)
{
        if (!sgl || !sgl_count)
                return 0;

        /*
         * Reject SCSI data overflow with map_mem_to_cmd() as incoming
         * scatterlists already have been set to follow what the fabric
         * passes for the original expected data transfer length.
         */
        if (cmd->se_cmd_flags & SCF_OVERFLOW_BIT) {
                pr_warn("Rejecting SCSI DATA overflow for fabric using"
                        " SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC\n");
                cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
                cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;
                return -EINVAL;
        }

        cmd->t_data_sg = sgl;
        cmd->t_data_nents = sgl_count;

        if (sgl_bidi && sgl_bidi_count) {
                cmd->t_bidi_data_sg = sgl_bidi;
                cmd->t_bidi_data_nents = sgl_bidi_count;
        }
        cmd->se_cmd_flags |= SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC;
        return 0;
}
EXPORT_SYMBOL(transport_generic_map_mem_to_cmd);

void *transport_kmap_data_sg(struct se_cmd *cmd)
{
        struct scatterlist *sg = cmd->t_data_sg;
        struct page **pages;
        int i;

        /*
         * We need to take into account a possible offset here for fabrics like
         * tcm_loop who may be using a contig buffer from the SCSI midlayer for
         * control CDBs passed as SGLs via transport_generic_map_mem_to_cmd()
         */
        if (!cmd->t_data_nents)
                return NULL;

        BUG_ON(!sg);
        if (cmd->t_data_nents == 1)
                return kmap(sg_page(sg)) + sg->offset;

        /* >1 page. use vmap */
        pages = kmalloc(sizeof(*pages) * cmd->t_data_nents, GFP_KERNEL);
        if (!pages) {
                cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                return NULL;
        }

        /* convert sg[] to pages[] */
        for_each_sg(cmd->t_data_sg, sg, cmd->t_data_nents, i) {
                pages[i] = sg_page(sg);
        }

        cmd->t_data_vmap = vmap(pages, cmd->t_data_nents,  VM_MAP, PAGE_KERNEL);
        kfree(pages);
        if (!cmd->t_data_vmap) {
                cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                return NULL;
        }

        return cmd->t_data_vmap + cmd->t_data_sg[0].offset;
}
EXPORT_SYMBOL(transport_kmap_data_sg);

void transport_kunmap_data_sg(struct se_cmd *cmd)
{
        if (!cmd->t_data_nents) {
                return;
        } else if (cmd->t_data_nents == 1) {
                kunmap(sg_page(cmd->t_data_sg));
                return;
        }

        vunmap(cmd->t_data_vmap);
        cmd->t_data_vmap = NULL;
}
EXPORT_SYMBOL(transport_kunmap_data_sg);

static int
transport_generic_get_mem(struct se_cmd *cmd)
{
        u32 length = cmd->data_length;
        unsigned int nents;
        struct page *page;
        gfp_t zero_flag;
        int i = 0;

        nents = DIV_ROUND_UP(length, PAGE_SIZE);
        cmd->t_data_sg = kmalloc(sizeof(struct scatterlist) * nents, GFP_KERNEL);
        if (!cmd->t_data_sg)
                return -ENOMEM;

        cmd->t_data_nents = nents;
        sg_init_table(cmd->t_data_sg, nents);

        zero_flag = cmd->se_cmd_flags & SCF_SCSI_DATA_CDB ? 0 : __GFP_ZERO;

        while (length) {
                u32 page_len = min_t(u32, length, PAGE_SIZE);
                page = alloc_page(GFP_KERNEL | zero_flag);
                if (!page)
                        goto out;

                sg_set_page(&cmd->t_data_sg[i], page, page_len, 0);
                length -= page_len;
                i++;
        }
        return 0;

out:
        while (i > 0) {
                i--;
                __free_page(sg_page(&cmd->t_data_sg[i]));
        }
        kfree(cmd->t_data_sg);
        cmd->t_data_sg = NULL;
        return -ENOMEM;
}

/*
 * Allocate any required resources to execute the command.  For writes we
 * might not have the payload yet, so notify the fabric via a call to
 * ->write_pending instead. Otherwise place it on the execution queue.
 */
int transport_generic_new_cmd(struct se_cmd *cmd)
{
        int ret = 0;

        /*
         * Determine is the TCM fabric module has already allocated physical
         * memory, and is directly calling transport_generic_map_mem_to_cmd()
         * beforehand.
         */
        if (!(cmd->se_cmd_flags & SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC) &&
            cmd->data_length) {
                ret = transport_generic_get_mem(cmd);
                if (ret < 0)
                        goto out_fail;
        }

        atomic_inc(&cmd->t_fe_count);

        /*
         * If this command is not a write we can execute it right here,
         * for write buffers we need to notify the fabric driver first
         * and let it call back once the write buffers are ready.
         */
        target_add_to_state_list(cmd);
        if (cmd->data_direction != DMA_TO_DEVICE) {
                target_execute_cmd(cmd);
                return 0;
        }

        spin_lock_irq(&cmd->t_state_lock);
        cmd->t_state = TRANSPORT_WRITE_PENDING;
        spin_unlock_irq(&cmd->t_state_lock);

        transport_cmd_check_stop(cmd, false);

        ret = cmd->se_tfo->write_pending(cmd);
        if (ret == -EAGAIN || ret == -ENOMEM)
                goto queue_full;

        if (ret < 0)
                return ret;
        return 1;

out_fail:
        cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
        cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
        return -EINVAL;
queue_full:
        pr_debug("Handling write_pending QUEUE__FULL: se_cmd: %p\n", cmd);
        cmd->t_state = TRANSPORT_COMPLETE_QF_WP;
        transport_handle_queue_full(cmd, cmd->se_dev);
        return 0;
}
EXPORT_SYMBOL(transport_generic_new_cmd);

static void transport_write_pending_qf(struct se_cmd *cmd)
{
        int ret;

        ret = cmd->se_tfo->write_pending(cmd);
        if (ret == -EAGAIN || ret == -ENOMEM) {
                pr_debug("Handling write_pending QUEUE__FULL: se_cmd: %p\n",
                         cmd);
                transport_handle_queue_full(cmd, cmd->se_dev);
        }
}

void transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks)
{
        if (!(cmd->se_cmd_flags & SCF_SE_LUN_CMD)) {
                if (wait_for_tasks && (cmd->se_cmd_flags & SCF_SCSI_TMR_CDB))
                         transport_wait_for_tasks(cmd);

                transport_release_cmd(cmd);
        } else {
                if (wait_for_tasks)
                        transport_wait_for_tasks(cmd);

                core_dec_lacl_count(cmd->se_sess->se_node_acl, cmd);

                if (cmd->se_lun)
                        transport_lun_remove_cmd(cmd);

                transport_put_cmd(cmd);
        }
}
EXPORT_SYMBOL(transport_generic_free_cmd);

/* target_get_sess_cmd - Add command to active ->sess_cmd_list
 * @se_sess:    session to reference
 * @se_cmd:     command descriptor to add
 * @ack_kref:   Signal that fabric will perform an ack target_put_sess_cmd()
 */
static int target_get_sess_cmd(struct se_session *se_sess, struct se_cmd *se_cmd,
                               bool ack_kref)
{
        unsigned long flags;
        int ret = 0;

        kref_init(&se_cmd->cmd_kref);
        /*
         * Add a second kref if the fabric caller is expecting to handle
         * fabric acknowledgement that requires two target_put_sess_cmd()
         * invocations before se_cmd descriptor release.
         */
        if (ack_kref == true) {
                kref_get(&se_cmd->cmd_kref);
                se_cmd->se_cmd_flags |= SCF_ACK_KREF;
        }

        spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
        if (se_sess->sess_tearing_down) {
                ret = -ESHUTDOWN;
                goto out;
        }
        list_add_tail(&se_cmd->se_cmd_list, &se_sess->sess_cmd_list);
        se_cmd->check_release = 1;

out:
        spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
        return ret;
}

static void target_release_cmd_kref(struct kref *kref)
{
        struct se_cmd *se_cmd = container_of(kref, struct se_cmd, cmd_kref);
        struct se_session *se_sess = se_cmd->se_sess;
        unsigned long flags;

        spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
        if (list_empty(&se_cmd->se_cmd_list)) {
                spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
                se_cmd->se_tfo->release_cmd(se_cmd);
                return;
        }
        if (se_sess->sess_tearing_down && se_cmd->cmd_wait_set) {
                spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
                complete(&se_cmd->cmd_wait_comp);
                return;
        }
        list_del(&se_cmd->se_cmd_list);
        spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);

        se_cmd->se_tfo->release_cmd(se_cmd);
}

/* target_put_sess_cmd - Check for active I/O shutdown via kref_put
 * @se_sess:    session to reference
 * @se_cmd:     command descriptor to drop
 */
int target_put_sess_cmd(struct se_session *se_sess, struct se_cmd *se_cmd)
{
        return kref_put(&se_cmd->cmd_kref, target_release_cmd_kref);
}
EXPORT_SYMBOL(target_put_sess_cmd);

/* target_sess_cmd_list_set_waiting - Flag all commands in
 *         sess_cmd_list to complete cmd_wait_comp.  Set
 *         sess_tearing_down so no more commands are queued.
 * @se_sess:    session to flag
 */
void target_sess_cmd_list_set_waiting(struct se_session *se_sess)
{
        struct se_cmd *se_cmd;
        unsigned long flags;

        spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);

        WARN_ON(se_sess->sess_tearing_down);
        se_sess->sess_tearing_down = 1;

        list_for_each_entry(se_cmd, &se_sess->sess_cmd_list, se_cmd_list)
                se_cmd->cmd_wait_set = 1;

        spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
}
EXPORT_SYMBOL(target_sess_cmd_list_set_waiting);

/* target_wait_for_sess_cmds - Wait for outstanding descriptors
 * @se_sess:    session to wait for active I/O
 * @wait_for_tasks:     Make extra transport_wait_for_tasks call
 */
void target_wait_for_sess_cmds(
        struct se_session *se_sess,
        int wait_for_tasks)
{
        struct se_cmd *se_cmd, *tmp_cmd;
        bool rc = false;

        list_for_each_entry_safe(se_cmd, tmp_cmd,
                                &se_sess->sess_cmd_list, se_cmd_list) {
                list_del(&se_cmd->se_cmd_list);

                pr_debug("Waiting for se_cmd: %p t_state: %d, fabric state:"
                        " %d\n", se_cmd, se_cmd->t_state,
                        se_cmd->se_tfo->get_cmd_state(se_cmd));

                if (wait_for_tasks) {
                        pr_debug("Calling transport_wait_for_tasks se_cmd: %p t_state: %d,"
                                " fabric state: %d\n", se_cmd, se_cmd->t_state,
                                se_cmd->se_tfo->get_cmd_state(se_cmd));

                        rc = transport_wait_for_tasks(se_cmd);

                        pr_debug("After transport_wait_for_tasks se_cmd: %p t_state: %d,"
                                " fabric state: %d\n", se_cmd, se_cmd->t_state,
                                se_cmd->se_tfo->get_cmd_state(se_cmd));
                }

                if (!rc) {
                        wait_for_completion(&se_cmd->cmd_wait_comp);
                        pr_debug("After cmd_wait_comp: se_cmd: %p t_state: %d"
                                " fabric state: %d\n", se_cmd, se_cmd->t_state,
                                se_cmd->se_tfo->get_cmd_state(se_cmd));
                }

                se_cmd->se_tfo->release_cmd(se_cmd);
        }
}
EXPORT_SYMBOL(target_wait_for_sess_cmds);

/*      transport_lun_wait_for_tasks():
 *
 *      Called from ConfigFS context to stop the passed struct se_cmd to allow
 *      an struct se_lun to be successfully shutdown.
 */
static int transport_lun_wait_for_tasks(struct se_cmd *cmd, struct se_lun *lun)
{
        unsigned long flags;
        int ret = 0;

        /*
         * If the frontend has already requested this struct se_cmd to
         * be stopped, we can safely ignore this struct se_cmd.
         */
        spin_lock_irqsave(&cmd->t_state_lock, flags);
        if (cmd->transport_state & CMD_T_STOP) {
                cmd->transport_state &= ~CMD_T_LUN_STOP;

                pr_debug("ConfigFS ITT[0x%08x] - CMD_T_STOP, skipping\n",
                         cmd->se_tfo->get_task_tag(cmd));
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                transport_cmd_check_stop(cmd, false);
                return -EPERM;
        }
        cmd->transport_state |= CMD_T_LUN_FE_STOP;
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);

        // XXX: audit task_flags checks.
        spin_lock_irqsave(&cmd->t_state_lock, flags);
        if ((cmd->transport_state & CMD_T_BUSY) &&
            (cmd->transport_state & CMD_T_SENT)) {
                if (!target_stop_cmd(cmd, &flags))
                        ret++;
        }
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);

        pr_debug("ConfigFS: cmd: %p stop tasks ret:"
                        " %d\n", cmd, ret);
        if (!ret) {
                pr_debug("ConfigFS: ITT[0x%08x] - stopping cmd....\n",
                                cmd->se_tfo->get_task_tag(cmd));
                wait_for_completion(&cmd->transport_lun_stop_comp);
                pr_debug("ConfigFS: ITT[0x%08x] - stopped cmd....\n",
                                cmd->se_tfo->get_task_tag(cmd));
        }

        return 0;
}

static void __transport_clear_lun_from_sessions(struct se_lun *lun)
{
        struct se_cmd *cmd = NULL;
        unsigned long lun_flags, cmd_flags;
        /*
         * Do exception processing and return CHECK_CONDITION status to the
         * Initiator Port.
         */
        spin_lock_irqsave(&lun->lun_cmd_lock, lun_flags);
        while (!list_empty(&lun->lun_cmd_list)) {
                cmd = list_first_entry(&lun->lun_cmd_list,
                       struct se_cmd, se_lun_node);
                list_del_init(&cmd->se_lun_node);

                spin_lock(&cmd->t_state_lock);
                pr_debug("SE_LUN[%d] - Setting cmd->transport"
                        "_lun_stop for  ITT: 0x%08x\n",
                        cmd->se_lun->unpacked_lun,
                        cmd->se_tfo->get_task_tag(cmd));
                cmd->transport_state |= CMD_T_LUN_STOP;
                spin_unlock(&cmd->t_state_lock);

                spin_unlock_irqrestore(&lun->lun_cmd_lock, lun_flags);

                if (!cmd->se_lun) {
                        pr_err("ITT: 0x%08x, [i,t]_state: %u/%u\n",
                                cmd->se_tfo->get_task_tag(cmd),
                                cmd->se_tfo->get_cmd_state(cmd), cmd->t_state);
                        BUG();
                }
                /*
                 * If the Storage engine still owns the iscsi_cmd_t, determine
                 * and/or stop its context.
                 */
                pr_debug("SE_LUN[%d] - ITT: 0x%08x before transport"
                        "_lun_wait_for_tasks()\n", cmd->se_lun->unpacked_lun,
                        cmd->se_tfo->get_task_tag(cmd));

                if (transport_lun_wait_for_tasks(cmd, cmd->se_lun) < 0) {
                        spin_lock_irqsave(&lun->lun_cmd_lock, lun_flags);
                        continue;
                }

                pr_debug("SE_LUN[%d] - ITT: 0x%08x after transport_lun"
                        "_wait_for_tasks(): SUCCESS\n",
                        cmd->se_lun->unpacked_lun,
                        cmd->se_tfo->get_task_tag(cmd));

                spin_lock_irqsave(&cmd->t_state_lock, cmd_flags);
                if (!(cmd->transport_state & CMD_T_DEV_ACTIVE)) {
                        spin_unlock_irqrestore(&cmd->t_state_lock, cmd_flags);
                        goto check_cond;
                }
                cmd->transport_state &= ~CMD_T_DEV_ACTIVE;
                target_remove_from_state_list(cmd);
                spin_unlock_irqrestore(&cmd->t_state_lock, cmd_flags);

                /*
                 * The Storage engine stopped this struct se_cmd before it was
                 * send to the fabric frontend for delivery back to the
                 * Initiator Node.  Return this SCSI CDB back with an
                 * CHECK_CONDITION status.
                 */
check_cond:
                transport_send_check_condition_and_sense(cmd,
                                TCM_NON_EXISTENT_LUN, 0);
                /*
                 *  If the fabric frontend is waiting for this iscsi_cmd_t to
                 * be released, notify the waiting thread now that LU has
                 * finished accessing it.
                 */
                spin_lock_irqsave(&cmd->t_state_lock, cmd_flags);
                if (cmd->transport_state & CMD_T_LUN_FE_STOP) {
                        pr_debug("SE_LUN[%d] - Detected FE stop for"
                                " struct se_cmd: %p ITT: 0x%08x\n",
                                lun->unpacked_lun,
                                cmd, cmd->se_tfo->get_task_tag(cmd));

                        spin_unlock_irqrestore(&cmd->t_state_lock,
                                        cmd_flags);
                        transport_cmd_check_stop(cmd, false);
                        complete(&cmd->transport_lun_fe_stop_comp);
                        spin_lock_irqsave(&lun->lun_cmd_lock, lun_flags);
                        continue;
                }
                pr_debug("SE_LUN[%d] - ITT: 0x%08x finished processing\n",
                        lun->unpacked_lun, cmd->se_tfo->get_task_tag(cmd));

                spin_unlock_irqrestore(&cmd->t_state_lock, cmd_flags);
                spin_lock_irqsave(&lun->lun_cmd_lock, lun_flags);
        }
        spin_unlock_irqrestore(&lun->lun_cmd_lock, lun_flags);
}

static int transport_clear_lun_thread(void *p)
{
        struct se_lun *lun = p;

        __transport_clear_lun_from_sessions(lun);
        complete(&lun->lun_shutdown_comp);

        return 0;
}

int transport_clear_lun_from_sessions(struct se_lun *lun)
{
        struct task_struct *kt;

        kt = kthread_run(transport_clear_lun_thread, lun,
                        "tcm_cl_%u", lun->unpacked_lun);
        if (IS_ERR(kt)) {
                pr_err("Unable to start clear_lun thread\n");
                return PTR_ERR(kt);
        }
        wait_for_completion(&lun->lun_shutdown_comp);

        return 0;
}

/**
 * transport_wait_for_tasks - wait for completion to occur
 * @cmd:        command to wait
 *
 * Called from frontend fabric context to wait for storage engine
 * to pause and/or release frontend generated struct se_cmd.
 */
bool transport_wait_for_tasks(struct se_cmd *cmd)
{
        unsigned long flags;

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        if (!(cmd->se_cmd_flags & SCF_SE_LUN_CMD) &&
            !(cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)) {
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                return false;
        }

        if (!(cmd->se_cmd_flags & SCF_SUPPORTED_SAM_OPCODE) &&
            !(cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)) {
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                return false;
        }
        /*
         * If we are already stopped due to an external event (ie: LUN shutdown)
         * sleep until the connection can have the passed struct se_cmd back.
         * The cmd->transport_lun_stopped_sem will be upped by
         * transport_clear_lun_from_sessions() once the ConfigFS context caller
         * has completed its operation on the struct se_cmd.
         */
        if (cmd->transport_state & CMD_T_LUN_STOP) {
                pr_debug("wait_for_tasks: Stopping"
                        " wait_for_completion(&cmd->t_tasktransport_lun_fe"
                        "_stop_comp); for ITT: 0x%08x\n",
                        cmd->se_tfo->get_task_tag(cmd));
                /*
                 * There is a special case for WRITES where a FE exception +
                 * LUN shutdown means ConfigFS context is still sleeping on
                 * transport_lun_stop_comp in transport_lun_wait_for_tasks().
                 * We go ahead and up transport_lun_stop_comp just to be sure
                 * here.
                 */
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                complete(&cmd->transport_lun_stop_comp);
                wait_for_completion(&cmd->transport_lun_fe_stop_comp);
                spin_lock_irqsave(&cmd->t_state_lock, flags);

                target_remove_from_state_list(cmd);
                /*
                 * At this point, the frontend who was the originator of this
                 * struct se_cmd, now owns the structure and can be released through
                 * normal means below.
                 */
                pr_debug("wait_for_tasks: Stopped"
                        " wait_for_completion(&cmd->t_tasktransport_lun_fe_"
                        "stop_comp); for ITT: 0x%08x\n",
                        cmd->se_tfo->get_task_tag(cmd));

                cmd->transport_state &= ~CMD_T_LUN_STOP;
        }

        if (!(cmd->transport_state & CMD_T_ACTIVE)) {
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                return false;
        }

        cmd->transport_state |= CMD_T_STOP;

        pr_debug("wait_for_tasks: Stopping %p ITT: 0x%08x"
                " i_state: %d, t_state: %d, CMD_T_STOP\n",
                cmd, cmd->se_tfo->get_task_tag(cmd),
                cmd->se_tfo->get_cmd_state(cmd), cmd->t_state);

        spin_unlock_irqrestore(&cmd->t_state_lock, flags);

        wait_for_completion(&cmd->t_transport_stop_comp);

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        cmd->transport_state &= ~(CMD_T_ACTIVE | CMD_T_STOP);

        pr_debug("wait_for_tasks: Stopped wait_for_completion("
                "&cmd->t_transport_stop_comp) for ITT: 0x%08x\n",
                cmd->se_tfo->get_task_tag(cmd));

        spin_unlock_irqrestore(&cmd->t_state_lock, flags);

        return true;
}
EXPORT_SYMBOL(transport_wait_for_tasks);

static int transport_get_sense_codes(
        struct se_cmd *cmd,
        u8 *asc,
        u8 *ascq)
{
        *asc = cmd->scsi_asc;
        *ascq = cmd->scsi_ascq;

        return 0;
}

static int transport_set_sense_codes(
        struct se_cmd *cmd,
        u8 asc,
        u8 ascq)
{
        cmd->scsi_asc = asc;
        cmd->scsi_ascq = ascq;

        return 0;
}

int transport_send_check_condition_and_sense(
        struct se_cmd *cmd,
        u8 reason,
        int from_transport)
{
        unsigned char *buffer = cmd->sense_buffer;
        unsigned long flags;
        u8 asc = 0, ascq = 0;

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        if (cmd->se_cmd_flags & SCF_SENT_CHECK_CONDITION) {
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                return 0;
        }
        cmd->se_cmd_flags |= SCF_SENT_CHECK_CONDITION;
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);

        if (!reason && from_transport)
                goto after_reason;

        if (!from_transport)
                cmd->se_cmd_flags |= SCF_EMULATED_TASK_SENSE;

        /*
         * Actual SENSE DATA, see SPC-3 7.23.2  SPC_SENSE_KEY_OFFSET uses
         * SENSE KEY values from include/scsi/scsi.h
         */
        switch (reason) {
        case TCM_NON_EXISTENT_LUN:
                /* CURRENT ERROR */
                buffer[0] = 0x70;
                buffer[SPC_ADD_SENSE_LEN_OFFSET] = 10;
                /* ILLEGAL REQUEST */
                buffer[SPC_SENSE_KEY_OFFSET] = ILLEGAL_REQUEST;
                /* LOGICAL UNIT NOT SUPPORTED */
                buffer[SPC_ASC_KEY_OFFSET] = 0x25;
                break;
        case TCM_UNSUPPORTED_SCSI_OPCODE:
        case TCM_SECTOR_COUNT_TOO_MANY:
                /* CURRENT ERROR */
                buffer[0] = 0x70;
                buffer[SPC_ADD_SENSE_LEN_OFFSET] = 10;
                /* ILLEGAL REQUEST */
                buffer[SPC_SENSE_KEY_OFFSET] = ILLEGAL_REQUEST;
                /* INVALID COMMAND OPERATION CODE */
                buffer[SPC_ASC_KEY_OFFSET] = 0x20;
                break;
        case TCM_UNKNOWN_MODE_PAGE:
                /* CURRENT ERROR */
                buffer[0] = 0x70;
                buffer[SPC_ADD_SENSE_LEN_OFFSET] = 10;
                /* ILLEGAL REQUEST */
                buffer[SPC_SENSE_KEY_OFFSET] = ILLEGAL_REQUEST;
                /* INVALID FIELD IN CDB */
                buffer[SPC_ASC_KEY_OFFSET] = 0x24;
                break;
        case TCM_CHECK_CONDITION_ABORT_CMD:
                /* CURRENT ERROR */
                buffer[0] = 0x70;
                buffer[SPC_ADD_SENSE_LEN_OFFSET] = 10;
                /* ABORTED COMMAND */
                buffer[SPC_SENSE_KEY_OFFSET] = ABORTED_COMMAND;
                /* BUS DEVICE RESET FUNCTION OCCURRED */
                buffer[SPC_ASC_KEY_OFFSET] = 0x29;
                buffer[SPC_ASCQ_KEY_OFFSET] = 0x03;
                break;
        case TCM_INCORRECT_AMOUNT_OF_DATA:
                /* CURRENT ERROR */
                buffer[0] = 0x70;
                buffer[SPC_ADD_SENSE_LEN_OFFSET] = 10;
                /* ABORTED COMMAND */
                buffer[SPC_SENSE_KEY_OFFSET] = ABORTED_COMMAND;
                /* WRITE ERROR */
                buffer[SPC_ASC_KEY_OFFSET] = 0x0c;
                /* NOT ENOUGH UNSOLICITED DATA */
                buffer[SPC_ASCQ_KEY_OFFSET] = 0x0d;
                break;
        case TCM_INVALID_CDB_FIELD:
                /* CURRENT ERROR */
                buffer[0] = 0x70;
                buffer[SPC_ADD_SENSE_LEN_OFFSET] = 10;
                /* ILLEGAL REQUEST */
                buffer[SPC_SENSE_KEY_OFFSET] = ILLEGAL_REQUEST;
                /* INVALID FIELD IN CDB */
                buffer[SPC_ASC_KEY_OFFSET] = 0x24;
                break;
        case TCM_INVALID_PARAMETER_LIST:
                /* CURRENT ERROR */
                buffer[0] = 0x70;
                buffer[SPC_ADD_SENSE_LEN_OFFSET] = 10;
                /* ILLEGAL REQUEST */
                buffer[SPC_SENSE_KEY_OFFSET] = ILLEGAL_REQUEST;
                /* INVALID FIELD IN PARAMETER LIST */
                buffer[SPC_ASC_KEY_OFFSET] = 0x26;
                break;
        case TCM_UNEXPECTED_UNSOLICITED_DATA:
                /* CURRENT ERROR */
                buffer[0] = 0x70;
                buffer[SPC_ADD_SENSE_LEN_OFFSET] = 10;
                /* ABORTED COMMAND */
                buffer[SPC_SENSE_KEY_OFFSET] = ABORTED_COMMAND;
                /* WRITE ERROR */
                buffer[SPC_ASC_KEY_OFFSET] = 0x0c;
                /* UNEXPECTED_UNSOLICITED_DATA */
                buffer[SPC_ASCQ_KEY_OFFSET] = 0x0c;
                break;
        case TCM_SERVICE_CRC_ERROR:
                /* CURRENT ERROR */
                buffer[0] = 0x70;
                buffer[SPC_ADD_SENSE_LEN_OFFSET] = 10;
                /* ABORTED COMMAND */
                buffer[SPC_SENSE_KEY_OFFSET] = ABORTED_COMMAND;
                /* PROTOCOL SERVICE CRC ERROR */
                buffer[SPC_ASC_KEY_OFFSET] = 0x47;
                /* N/A */
                buffer[SPC_ASCQ_KEY_OFFSET] = 0x05;
                break;
        case TCM_SNACK_REJECTED:
                /* CURRENT ERROR */
                buffer[0] = 0x70;
                buffer[SPC_ADD_SENSE_LEN_OFFSET] = 10;
                /* ABORTED COMMAND */
                buffer[SPC_SENSE_KEY_OFFSET] = ABORTED_COMMAND;
                /* READ ERROR */
                buffer[SPC_ASC_KEY_OFFSET] = 0x11;
                /* FAILED RETRANSMISSION REQUEST */
                buffer[SPC_ASCQ_KEY_OFFSET] = 0x13;
                break;
        case TCM_WRITE_PROTECTED:
                /* CURRENT ERROR */
                buffer[0] = 0x70;
                buffer[SPC_ADD_SENSE_LEN_OFFSET] = 10;
                /* DATA PROTECT */
                buffer[SPC_SENSE_KEY_OFFSET] = DATA_PROTECT;
                /* WRITE PROTECTED */
                buffer[SPC_ASC_KEY_OFFSET] = 0x27;
                break;
        case TCM_ADDRESS_OUT_OF_RANGE:
                /* CURRENT ERROR */
                buffer[0] = 0x70;
                buffer[SPC_ADD_SENSE_LEN_OFFSET] = 10;
                /* ILLEGAL REQUEST */
                buffer[SPC_SENSE_KEY_OFFSET] = ILLEGAL_REQUEST;
                /* LOGICAL BLOCK ADDRESS OUT OF RANGE */
                buffer[SPC_ASC_KEY_OFFSET] = 0x21;
                break;
        case TCM_CHECK_CONDITION_UNIT_ATTENTION: