/*******************************************************************************
 * Filename:  target_core_transport.c
 *
 * This file contains the Generic Target Engine Core.
 *
 * (c) Copyright 2002-2013 Datera, Inc.
 *
 * 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/spinlock.h>
#include <linux/kthread.h>
#include <linux/in.h>
#include <linux/cdrom.h>
#include <linux/module.h>
#include <linux/ratelimit.h>
#include <linux/vmalloc.h>
#include <asm/unaligned.h>
#include <net/sock.h>
#include <net/tcp.h>
#include <scsi/scsi_proto.h>
#include <scsi/scsi_common.h>

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

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

#define CREATE_TRACE_POINTS
#include <trace/events/target.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_lba_map_cache;
struct kmem_cache *t10_alua_lba_map_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_put_cmd(struct se_cmd *cmd);
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_lba_map_cache = kmem_cache_create(
                        "t10_alua_lba_map_cache",
                        sizeof(struct t10_alua_lba_map),
                        __alignof__(struct t10_alua_lba_map), 0, NULL);
        if (!t10_alua_lba_map_cache) {
                pr_err("kmem_cache_create() for t10_alua_lba_map_"
                                "cache failed\n");
                goto out_free_tg_pt_gp_cache;
        }
        t10_alua_lba_map_mem_cache = kmem_cache_create(
                        "t10_alua_lba_map_mem_cache",
                        sizeof(struct t10_alua_lba_map_member),
                        __alignof__(struct t10_alua_lba_map_member), 0, NULL);
        if (!t10_alua_lba_map_mem_cache) {
                pr_err("kmem_cache_create() for t10_alua_lba_map_mem_"
                                "cache failed\n");
                goto out_free_lba_map_cache;
        }

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

        return 0;

out_free_lba_map_mem_cache:
        kmem_cache_destroy(t10_alua_lba_map_mem_cache);
out_free_lba_map_cache:
        kmem_cache_destroy(t10_alua_lba_map_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_lba_map_cache);
        kmem_cache_destroy(t10_alua_lba_map_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");

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

        sub_api_initialized = 1;
}

struct se_session *transport_init_session(enum target_prot_op sup_prot_ops)
{
        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);
        INIT_LIST_HEAD(&se_sess->sess_wait_list);
        spin_lock_init(&se_sess->sess_cmd_lock);
        se_sess->sup_prot_ops = sup_prot_ops;

        return se_sess;
}
EXPORT_SYMBOL(transport_init_session);

int transport_alloc_session_tags(struct se_session *se_sess,
                                 unsigned int tag_num, unsigned int tag_size)
{
        int rc;

        se_sess->sess_cmd_map = kzalloc(tag_num * tag_size,
                                        GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
        if (!se_sess->sess_cmd_map) {
                se_sess->sess_cmd_map = vzalloc(tag_num * tag_size);
                if (!se_sess->sess_cmd_map) {
                        pr_err("Unable to allocate se_sess->sess_cmd_map\n");
                        return -ENOMEM;
                }
        }

        rc = percpu_ida_init(&se_sess->sess_tag_pool, tag_num);
        if (rc < 0) {
                pr_err("Unable to init se_sess->sess_tag_pool,"
                        " tag_num: %u\n", tag_num);
                kvfree(se_sess->sess_cmd_map);
                se_sess->sess_cmd_map = NULL;
                return -ENOMEM;
        }

        return 0;
}
EXPORT_SYMBOL(transport_alloc_session_tags);

struct se_session *transport_init_session_tags(unsigned int tag_num,
                                               unsigned int tag_size,
                                               enum target_prot_op sup_prot_ops)
{
        struct se_session *se_sess;
        int rc;

        if (tag_num != 0 && !tag_size) {
                pr_err("init_session_tags called with percpu-ida tag_num:"
                       " %u, but zero tag_size\n", tag_num);
                return ERR_PTR(-EINVAL);
        }
        if (!tag_num && tag_size) {
                pr_err("init_session_tags called with percpu-ida tag_size:"
                       " %u, but zero tag_num\n", tag_size);
                return ERR_PTR(-EINVAL);
        }

        se_sess = transport_init_session(sup_prot_ops);
        if (IS_ERR(se_sess))
                return se_sess;

        rc = transport_alloc_session_tags(se_sess, tag_num, tag_size);
        if (rc < 0) {
                transport_free_session(se_sess);
                return ERR_PTR(-ENOMEM);
        }

        return se_sess;
}
EXPORT_SYMBOL(transport_init_session_tags);

/*
 * 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)
{
        const struct target_core_fabric_ops *tfo = se_tpg->se_tpg_tfo;
        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) {
                /*
                 *
                 * Determine if fabric allows for T10-PI feature bits exposed to
                 * initiators for device backends with !dev->dev_attrib.pi_prot_type.
                 *
                 * If so, then always save prot_type on a per se_node_acl node
                 * basis and re-instate the previous sess_prot_type to avoid
                 * disabling PI from below any previously initiator side
                 * registered LUNs.
                 */
                if (se_nacl->saved_prot_type)
                        se_sess->sess_prot_type = se_nacl->saved_prot_type;
                else if (tfo->tpg_check_prot_fabric_only)
                        se_sess->sess_prot_type = se_nacl->saved_prot_type =
                                        tfo->tpg_check_prot_fabric_only(se_tpg);
                /*
                 * 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]);
                }

                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);

struct se_session *
target_alloc_session(struct se_portal_group *tpg,
                     unsigned int tag_num, unsigned int tag_size,
                     enum target_prot_op prot_op,
                     const char *initiatorname, void *private,
                     int (*callback)(struct se_portal_group *,
                                     struct se_session *, void *))
{
        struct se_session *sess;

        /*
         * If the fabric driver is using percpu-ida based pre allocation
         * of I/O descriptor tags, go ahead and perform that setup now..
         */
        if (tag_num != 0)
                sess = transport_init_session_tags(tag_num, tag_size, prot_op);
        else
                sess = transport_init_session(prot_op);

        if (IS_ERR(sess))
                return sess;

        sess->se_node_acl = core_tpg_check_initiator_node_acl(tpg,
                                        (unsigned char *)initiatorname);
        if (!sess->se_node_acl) {
                transport_free_session(sess);
                return ERR_PTR(-EACCES);
        }
        /*
         * Go ahead and perform any remaining fabric setup that is
         * required before transport_register_session().
         */
        if (callback != NULL) {
                int rc = callback(tpg, sess, private);
                if (rc) {
                        transport_free_session(sess);
                        return ERR_PTR(rc);
                }
        }

        transport_register_session(tpg, sess->se_node_acl, sess, private);
        return sess;
}
EXPORT_SYMBOL(target_alloc_session);

ssize_t target_show_dynamic_sessions(struct se_portal_group *se_tpg, char *page)
{
        struct se_session *se_sess;
        ssize_t len = 0;

        spin_lock_bh(&se_tpg->session_lock);
        list_for_each_entry(se_sess, &se_tpg->tpg_sess_list, sess_list) {
                if (!se_sess->se_node_acl)
                        continue;
                if (!se_sess->se_node_acl->dynamic_node_acl)
                        continue;
                if (strlen(se_sess->se_node_acl->initiatorname) + 1 + len > PAGE_SIZE)
                        break;

                len += snprintf(page + len, PAGE_SIZE - len, "%s\n",
                                se_sess->se_node_acl->initiatorname);
                len += 1; /* Include NULL terminator */
        }
        spin_unlock_bh(&se_tpg->session_lock);

        return len;
}
EXPORT_SYMBOL(target_show_dynamic_sessions);

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);
}
EXPORT_SYMBOL(target_put_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 (!list_empty(&se_sess->sess_acl_list))
                        list_del_init(&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)
{
        struct se_node_acl *se_nacl = se_sess->se_node_acl;
        /*
         * Drop the se_node_acl->nacl_kref obtained from within
         * core_tpg_get_initiator_node_acl().
         */
        if (se_nacl) {
                se_sess->se_node_acl = NULL;
                target_put_nacl(se_nacl);
        }
        if (se_sess->sess_cmd_map) {
                percpu_ida_destroy(&se_sess->sess_tag_pool);
                kvfree(se_sess->sess_cmd_map);
        }
        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;
        const struct target_core_fabric_ops *se_tfo;
        struct se_node_acl *se_nacl;
        unsigned long flags;
        bool drop_nacl = false;

        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;

        mutex_lock(&se_tpg->acl_node_mutex);
        if (se_nacl && se_nacl->dynamic_node_acl) {
                if (!se_tfo->tpg_check_demo_mode_cache(se_tpg)) {
                        list_del(&se_nacl->acl_list);
                        drop_nacl = true;
                }
        }
        mutex_unlock(&se_tpg->acl_node_mutex);

        if (drop_nacl) {
                core_tpg_wait_for_nacl_pr_ref(se_nacl);
                core_free_device_list_for_node(se_nacl, se_tpg);
                se_sess->se_node_acl = NULL;
                kfree(se_nacl);
        }
        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 explicit NodeACL, awake sleeping
         * ->acl_free_comp caller to wakeup configfs se_node_acl->acl_group
         * removal context from within transport_free_session() code.
         */

        transport_free_session(se_sess);
}
EXPORT_SYMBOL(transport_deregister_session);

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,
                                    bool write_pending)
{
        unsigned long flags;

        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;
        }

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        if (write_pending)
                cmd->t_state = TRANSPORT_WRITE_PENDING;

        /*
         * 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%08llx\n",
                        __func__, __LINE__, cmd->tag);

                spin_unlock_irqrestore(&cmd->t_state_lock, flags);

                complete_all(&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, false);
}

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

        if (!lun)
                return;

        if (cmpxchg(&cmd->lun_ref_active, true, false))
                percpu_ref_put(&lun->lun_ref);
}

void transport_cmd_finish_abort(struct se_cmd *cmd, int remove)
{
        bool ack_kref = (cmd->se_cmd_flags & SCF_ACK_KREF);

        if (cmd->se_cmd_flags & SCF_SE_LUN_CMD)
                transport_lun_remove_cmd(cmd);
        /*
         * Allow the fabric driver to unmap any resources before
         * releasing the descriptor via TFO->release_cmd()
         */
        if (remove)
                cmd->se_tfo->aborted_task(cmd);

        if (transport_cmd_check_stop_to_fabric(cmd))
                return;
        if (remove && ack_kref)
                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,
                        TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE);
}

/*
 * 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;
        }

        /*
         * Check for case where an explicit 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_all(&cmd->t_transport_stop_comp);
                return;
        } else if (!success) {
                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);

        if (cmd->se_cmd_flags & SCF_USE_CPUID)
                queue_work_on(cmd->cpuid, target_completion_wq, &cmd->work);
        else
                queue_work(target_completion_wq, &cmd->work);
}
EXPORT_SYMBOL(target_complete_cmd);

void target_complete_cmd_with_length(struct se_cmd *cmd, u8 scsi_status, int length)
{
        if (scsi_status == SAM_STAT_GOOD && length < cmd->data_length) {
                if (cmd->se_cmd_flags & SCF_UNDERFLOW_BIT) {
                        cmd->residual_count += cmd->data_length - length;
                } else {
                        cmd->se_cmd_flags |= SCF_UNDERFLOW_BIT;
                        cmd->residual_count = cmd->data_length - length;
                }

                cmd->data_length = length;
        }

        target_complete_cmd(cmd, scsi_status);
}
EXPORT_SYMBOL(target_complete_cmd_with_length);

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);

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_mb(&dev->dev_qf_count);

                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: ");
        if (dev->export_count)
                *bl += sprintf(b + *bl, "ACTIVATED");
        else
                *bl += sprintf(b + *bl, "DEACTIVATED");

        *bl += sprintf(b + *bl, "  Max Queue Depth: %d", dev->queue_depth);
        *bl += sprintf(b + *bl, "  SectorSize: %u  HwMaxSectors: %u\n",
                dev->dev_attrib.block_size,
                dev->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 */
                snprintf(buf, sizeof(buf),
                        "T10 VPD Binary Device Identifier: %s\n",
                        &vpd->device_identifier[0]);
                break;
        case 0x02: /* ASCII */
                snprintf(buf, sizeof(buf),
                        "T10 VPD ASCII Device Identifier: %s\n",
                        &vpd->device_identifier[0]);
                break;
        case 0x03: /* UTF-8 */
                snprintf(buf, sizeof(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 sense_reason_t
target_check_max_data_sg_nents(struct se_cmd *cmd, struct se_device *dev,
                               unsigned int size)
{
        u32 mtl;

        if (!cmd->se_tfo->max_data_sg_nents)
                return TCM_NO_SENSE;
        /*
         * Check if fabric enforced maximum SGL entries per I/O descriptor
         * exceeds se_cmd->data_length.  If true, set SCF_UNDERFLOW_BIT +
         * residual_count and reduce original cmd->data_length to maximum
         * length based on single PAGE_SIZE entry scatter-lists.
         */
        mtl = (cmd->se_tfo->max_data_sg_nents * PAGE_SIZE);
        if (cmd->data_length > mtl) {
                /*
                 * If an existing CDB overflow is present, calculate new residual
                 * based on CDB size minus fabric maximum transfer length.
                 *
                 * If an existing CDB underflow is present, calculate new residual
                 * based on original cmd->data_length minus fabric maximum transfer
                 * length.
                 *
                 * Otherwise, set the underflow residual based on cmd->data_length
                 * minus fabric maximum transfer length.
                 */
                if (cmd->se_cmd_flags & SCF_OVERFLOW_BIT) {
                        cmd->residual_count = (size - mtl);
                } else if (cmd->se_cmd_flags & SCF_UNDERFLOW_BIT) {
                        u32 orig_dl = size + cmd->residual_count;
                        cmd->residual_count = (orig_dl - mtl);
                } else {
                        cmd->se_cmd_flags |= SCF_UNDERFLOW_BIT;
                        cmd->residual_count = (cmd->data_length - mtl);
                }
                cmd->data_length = mtl;
                /*
                 * Reset sbc_check_prot() calculated protection payload
                 * length based upon the new smaller MTL.
                 */
                if (cmd->prot_length) {
                        u32 sectors = (mtl / dev->dev_attrib.block_size);
                        cmd->prot_length = dev->prot_length * sectors;
                }
        }
        return TCM_NO_SENSE;
}

sense_reason_t
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 &&
                    cmd->se_cmd_flags & SCF_SCSI_DATA_CDB) {
                        pr_err("Rejecting underflow/overflow WRITE data\n");
                        return TCM_INVALID_CDB_FIELD;
                }
                /*
                 * Reject READ_* or WRITE_* with overflow/underflow for
                 * type SCF_SCSI_DATA_CDB.
                 */
                if (dev->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 */
                        return TCM_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 target_check_max_data_sg_nents(cmd, dev, size);

}

/*
 * Used by fabric modules containing a local struct se_cmd within their
 * fabric dependent per I/O descriptor.
 *
 * Preserves the value of @cmd->tag.
 */
void transport_init_se_cmd(
        struct se_cmd *cmd,
        const 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_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->t_transport_stop_comp);
        init_completion(&cmd->cmd_wait_comp);
        spin_lock_init(&cmd->t_state_lock);
        kref_init(&cmd->cmd_kref);
        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 sense_reason_t
transport_check_alloc_task_attr(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;

        /*
         * Check if SAM Task Attribute emulation is enabled for this
         * struct se_device storage object
         */
        if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH)
                return 0;

        if (cmd->sam_task_attr == TCM_ACA_TAG) {
                pr_debug("SAM Task Attribute ACA"
                        " emulation is not supported\n");
                return TCM_INVALID_CDB_FIELD;
        }

        return 0;
}

sense_reason_t
target_setup_cmd_from_cdb(struct se_cmd *cmd, unsigned char *cdb)
{
        struct se_device *dev = cmd->se_dev;
        sense_reason_t 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);
                return TCM_INVALID_CDB_FIELD;
        }
        /*
         * 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));
                        return TCM_OUT_OF_RESOURCES;
                }
        } 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));

        trace_target_sequencer_start(cmd);

        ret = dev->transport->parse_cdb(cmd);
        if (ret == TCM_UNSUPPORTED_SCSI_OPCODE)
                pr_warn_ratelimited("%s/%s: Unsupported SCSI Opcode 0x%02x, sending CHECK_CONDITION.\n",
                                    cmd->se_tfo->get_fabric_name(),
                                    cmd->se_sess->se_node_acl->initiatorname,
                                    cmd->t_task_cdb[0]);
        if (ret)
                return ret;

        ret = transport_check_alloc_task_attr(cmd);
        if (ret)
                return ret;

        cmd->se_cmd_flags |= SCF_SUPPORTED_SAM_OPCODE;
        atomic_long_inc(&cmd->se_lun->lun_stats.cmd_pdus);
        return 0;
}
EXPORT_SYMBOL(target_setup_cmd_from_cdb);

/*
 * Used by fabric module frontends to queue tasks directly.
 * May only be used from process context.
 */
int transport_handle_cdb_direct(
        struct se_cmd *cmd)
{
        sense_reason_t 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)
                transport_generic_request_failure(cmd, ret);
        return 0;
}
EXPORT_SYMBOL(transport_handle_cdb_direct);

sense_reason_t
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");
                return TCM_INVALID_CDB_FIELD;
        }

        cmd->t_data_sg = sgl;
        cmd->t_data_nents = sgl_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;
}

/*
 * 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
 * @sgl_prot: struct scatterlist memory protection information
 * @sgl_prot_count: scatterlist count for protection information
 *
 * Task tags are supported if the caller has set @se_cmd->tag.
 *
 * 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, u64 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 scatterlist *sgl_prot, u32 sgl_prot_count)
{
        struct se_portal_group *se_tpg;
        sense_reason_t rc;
        int ret;

        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_USE_CPUID)
                se_cmd->se_cmd_flags |= SCF_USE_CPUID;
        else
                se_cmd->cpuid = WORK_CPU_UNBOUND;

        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.
         */
        ret = target_get_sess_cmd(se_cmd, flags & TARGET_SCF_ACK_KREF);
        if (ret)
                return ret;
        /*
         * 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
         */
        rc = transport_lookup_cmd_lun(se_cmd, unpacked_lun);
        if (rc) {
                transport_send_check_condition_and_sense(se_cmd, rc, 0);
                target_put_sess_cmd(se_cmd);
                return 0;
        }

        rc = target_setup_cmd_from_cdb(se_cmd, cdb);
        if (rc != 0) {
                transport_generic_request_failure(se_cmd, rc);
                return 0;
        }

        /*
         * Save pointers for SGLs containing protection information,
         * if present.
         */
        if (sgl_prot_count) {
                se_cmd->t_prot_sg = sgl_prot;
                se_cmd->t_prot_nents = sgl_prot_count;
                se_cmd->se_cmd_flags |= SCF_PASSTHROUGH_PROT_SG_TO_MEM_NOALLOC;
        }

        /*
         * 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, rc);
                        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
 *
 * Task tags are supported if the caller has set @se_cmd->tag.
 *
 * 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, u64 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, 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, u64 unpacked_lun,
                void *fabric_tmr_ptr, unsigned char tm_type,
                gfp_t gfp, u64 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, TCM_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_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);

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

        pr_debug("-----[ Storage Engine Exception for cmd: %p ITT: 0x%08llx"
                " CDB: 0x%02x\n", cmd, cmd->tag, cmd->t_task_cdb[0]);
        pr_debug("-----[ i_state: %d t_state: %d sense_reason: %d\n",
                cmd->se_tfo->get_cmd_state(cmd),
                cmd->t_state, 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
         */
        transport_complete_task_attr(cmd);
        /*
         * Handle special case for COMPARE_AND_WRITE failure, where the
         * callback is expected to drop the per device ->caw_sem.
         */
        if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) &&
             cmd->transport_complete_callback)
                cmd->transport_complete_callback(cmd, false, &post_ret);

        switch (sense_reason) {
        case TCM_NON_EXISTENT_LUN:
        case TCM_UNSUPPORTED_SCSI_OPCODE:
        case TCM_INVALID_CDB_FIELD:
        case TCM_INVALID_PARAMETER_LIST:
        case TCM_PARAMETER_LIST_LENGTH_ERROR:
        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:
        case TCM_LOGICAL_BLOCK_GUARD_CHECK_FAILED:
        case TCM_LOGICAL_BLOCK_APP_TAG_CHECK_FAILED:
        case TCM_LOGICAL_BLOCK_REF_TAG_CHECK_FAILED:
        case TCM_COPY_TARGET_DEVICE_NOT_REACHABLE:
                break;
        case TCM_OUT_OF_RESOURCES:
                sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                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->dev_attrib.emulate_ua_intlck_ctrl == 2) {
                        target_ua_allocate_lun(cmd->se_sess->se_node_acl,
                                               cmd->orig_fe_lun, 0x2C,
                                        ASCQ_2CH_PREVIOUS_RESERVATION_CONFLICT_STATUS);
                }
                trace_target_cmd_complete(cmd);
                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], sense_reason);
                sense_reason = TCM_UNSUPPORTED_SCSI_OPCODE;
                break;
        }

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

check_stop:
        transport_lun_remove_cmd(cmd);
        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);

void __target_execute_cmd(struct se_cmd *cmd, bool do_checks)
{
        sense_reason_t ret;

        if (!cmd->execute_cmd) {
                ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                goto err;
        }
        if (do_checks) {
                /*
                 * Check for an existing UNIT ATTENTION condition after
                 * target_handle_task_attr() has done SAM task attr
                 * checking, and possibly have already defered execution
                 * out to target_restart_delayed_cmds() context.
                 */
                ret = target_scsi3_ua_check(cmd);
                if (ret)
                        goto err;

                ret = target_alua_state_check(cmd);
                if (ret)
                        goto err;

                ret = target_check_reservation(cmd);
                if (ret) {
                        cmd->scsi_status = SAM_STAT_RESERVATION_CONFLICT;
                        goto err;
                }
        }

        ret = cmd->execute_cmd(cmd);
        if (!ret)
                return;
err:
        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, ret);
}

static int target_write_prot_action(struct se_cmd *cmd)
{
        u32 sectors;
        /*
         * Perform WRITE_INSERT of PI using software emulation when backend
         * device has PI enabled, if the transport has not already generated
         * PI using hardware WRITE_INSERT offload.
         */
        switch (cmd->prot_op) {
        case TARGET_PROT_DOUT_INSERT:
                if (!(cmd->se_sess->sup_prot_ops & TARGET_PROT_DOUT_INSERT))
                        sbc_dif_generate(cmd);
                break;
        case TARGET_PROT_DOUT_STRIP:
                if (cmd->se_sess->sup_prot_ops & TARGET_PROT_DOUT_STRIP)
                        break;

                sectors = cmd->data_length >> ilog2(cmd->se_dev->dev_attrib.block_size);
                cmd->pi_err = sbc_dif_verify(cmd, cmd->t_task_lba,
                                             sectors, 0, cmd->t_prot_sg, 0);
                if (unlikely(cmd->pi_err)) {
                        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, cmd->pi_err);
                        return -1;
                }
                break;
        default:
                break;
        }

        return 0;
}

static bool target_handle_task_attr(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;

        if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH)
                return false;

        cmd->se_cmd_flags |= SCF_TASK_ATTR_SET;

        /*
         * 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 TCM_HEAD_TAG:
                pr_debug("Added HEAD_OF_QUEUE for CDB: 0x%02x\n",
                         cmd->t_task_cdb[0]);
                return false;
        case TCM_ORDERED_TAG:
                atomic_inc_mb(&dev->dev_ordered_sync);

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

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

        if (atomic_read(&dev->dev_ordered_sync) == 0)
                return false;

        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 listn",
                cmd->t_task_cdb[0], cmd->sam_task_attr);
        return true;
}

static int __transport_check_aborted_status(struct se_cmd *, int);

void target_execute_cmd(struct se_cmd *cmd)
{
        /*
         * Determine if frontend context caller is requesting the stopping of
         * this command for frontend exceptions.
         *
         * If the received CDB has aleady been aborted stop processing it here.
         */
        spin_lock_irq(&cmd->t_state_lock);
        if (__transport_check_aborted_status(cmd, 1)) {
                spin_unlock_irq(&cmd->t_state_lock);
                return;
        }
        if (cmd->transport_state & CMD_T_STOP) {
                pr_debug("%s:%d CMD_T_STOP for ITT: 0x%08llx\n",
                        __func__, __LINE__, cmd->tag);

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

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

        if (target_write_prot_action(cmd))
                return;

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

        __target_execute_cmd(cmd, true);
}
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, true);

                if (cmd->sam_task_attr == TCM_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 (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH)
                return;

        if (!(cmd->se_cmd_flags & SCF_TASK_ATTR_SET))
                goto restart;

        if (cmd->sam_task_attr == TCM_SIMPLE_TAG) {
                atomic_dec_mb(&dev->simple_cmds);
                dev->dev_cur_ordered_id++;
                pr_debug("Incremented dev->dev_cur_ordered_id: %u for SIMPLE\n",
                         dev->dev_cur_ordered_id);
        } else if (cmd->sam_task_attr == TCM_HEAD_TAG) {
                dev->dev_cur_ordered_id++;
                pr_debug("Incremented dev_cur_ordered_id: %u for HEAD_OF_QUEUE\n",
                         dev->dev_cur_ordered_id);
        } else if (cmd->sam_task_attr == TCM_ORDERED_TAG) {
                atomic_dec_mb(&dev->dev_ordered_sync);

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

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

        transport_complete_task_attr(cmd);

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

        switch (cmd->data_direction) {
        case DMA_FROM_DEVICE:
                if (cmd->scsi_status)
                        goto queue_status;

                trace_target_cmd_complete(cmd);
                ret = cmd->se_tfo->queue_data_in(cmd);
                break;
        case DMA_TO_DEVICE:
                if (cmd->se_cmd_flags & SCF_BIDI) {
                        ret = cmd->se_tfo->queue_data_in(cmd);

                        break;
                }
                /* Fall through for DMA_TO_DEVICE */
        case DMA_NONE:
queue_status:
                trace_target_cmd_complete(cmd);
                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_mb(&dev->dev_qf_count);
        spin_unlock_irq(&cmd->se_dev->qf_cmd_lock);

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

static bool target_read_prot_action(struct se_cmd *cmd)
{
        switch (cmd->prot_op) {
        case TARGET_PROT_DIN_STRIP:
                if (!(cmd->se_sess->sup_prot_ops & TARGET_PROT_DIN_STRIP)) {
                        u32 sectors = cmd->data_length >>
                                  ilog2(cmd->se_dev->dev_attrib.block_size);

                        cmd->pi_err = sbc_dif_verify(cmd, cmd->t_task_lba,
                                                     sectors, 0, cmd->t_prot_sg,
                                                     0);
                        if (cmd->pi_err)
                                return true;
                }
                break;
        case TARGET_PROT_DIN_INSERT:
                if (cmd->se_sess->sup_prot_ops & TARGET_PROT_DIN_INSERT)
                        break;

                sbc_dif_generate(cmd);
                break;
        default:
                break;
        }

        return false;
}

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.
         */
        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 and COMPARE_AND_WRITE emulation.
         */
        if (cmd->transport_complete_callback) {
                sense_reason_t rc;
                bool caw = (cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE);
                bool zero_dl = !(cmd->data_length);
                int post_ret = 0;

                rc = cmd->transport_complete_callback(cmd, true, &post_ret);
                if (!rc && !post_ret) {
                        if (caw && zero_dl)
                                goto queue_rsp;

                        return;
                } else if (rc) {
                        ret = transport_send_check_condition_and_sense(cmd,
                                                rc, 0);
                        if (ret == -EAGAIN || ret == -ENOMEM)
                                goto queue_full;

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

queue_rsp:
        switch (cmd->data_direction) {
        case DMA_FROM_DEVICE:
                if (cmd->scsi_status)
                        goto queue_status;

                atomic_long_add(cmd->data_length,
                                &cmd->se_lun->lun_stats.tx_data_octets);
                /*
                 * Perform READ_STRIP of PI using software emulation when
                 * backend had PI enabled, if the transport will not be
                 * performing hardware READ_STRIP offload.
                 */
                if (target_read_prot_action(cmd)) {
                        ret = transport_send_check_condition_and_sense(cmd,
                                                cmd->pi_err, 0);
                        if (ret == -EAGAIN || ret == -ENOMEM)
                                goto queue_full;

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

                trace_target_cmd_complete(cmd);
                ret = cmd->se_tfo->queue_data_in(cmd);
                if (ret == -EAGAIN || ret == -ENOMEM)
                        goto queue_full;
                break;
        case DMA_TO_DEVICE:
                atomic_long_add(cmd->data_length,
                                &cmd->se_lun->lun_stats.rx_data_octets);
                /*
                 * Check if we need to send READ payload for BIDI-COMMAND
                 */
                if (cmd->se_cmd_flags & SCF_BIDI) {
                        atomic_long_add(cmd->data_length,
                                        &cmd->se_lun->lun_stats.tx_data_octets);
                        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:
queue_status:
                trace_target_cmd_complete(cmd);
                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);
}

void target_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);
}
EXPORT_SYMBOL(target_free_sgl);

static inline void transport_reset_sgl_orig(struct se_cmd *cmd)
{
        /*
         * Check for saved t_data_sg that may be used for COMPARE_AND_WRITE
         * emulation, and free + reset pointers if necessary..
         */
        if (!cmd->t_data_sg_orig)
                return;

        kfree(cmd->t_data_sg);
        cmd->t_data_sg = cmd->t_data_sg_orig;
        cmd->t_data_sg_orig = NULL;
        cmd->t_data_nents = cmd->t_data_nents_orig;
        cmd->t_data_nents_orig = 0;
}

static inline void transport_free_pages(struct se_cmd *cmd)
{
        if (!(cmd->se_cmd_flags & SCF_PASSTHROUGH_PROT_SG_TO_MEM_NOALLOC)) {
                target_free_sgl(cmd->t_prot_sg, cmd->t_prot_nents);
                cmd->t_prot_sg = NULL;
                cmd->t_prot_nents = 0;
        }

        if (cmd->se_cmd_flags & SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC) {
                /*
                 * Release special case READ buffer payload required for
                 * SG_TO_MEM_NOALLOC to function with COMPARE_AND_WRITE
                 */
                if (cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) {
                        target_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_reset_sgl_orig(cmd);
                return;
        }
        transport_reset_sgl_orig(cmd);

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

        target_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_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 int transport_put_cmd(struct se_cmd *cmd)
{
        BUG_ON(!cmd->se_tfo);
        /*
         * If this cmd has been setup with target_get_sess_cmd(), drop
         * the kref and call ->release_cmd() in kref callback.
         */
        return target_put_sess_cmd(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)
                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)
                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);

int
target_alloc_sgl(struct scatterlist **sgl, unsigned int *nents, u32 length,
                 bool zero_page, bool chainable)
{
        struct scatterlist *sg;
        struct page *page;
        gfp_t zero_flag = (zero_page) ? __GFP_ZERO : 0;
        unsigned int nalloc, nent;
        int i = 0;

        nalloc = nent = DIV_ROUND_UP(length, PAGE_SIZE);
        if (chainable)
                nalloc++;
        sg = kmalloc_array(nalloc, sizeof(struct scatterlist), GFP_KERNEL);
        if (!sg)
                return -ENOMEM;

        sg_init_table(sg, nalloc);

        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(&sg[i], page, page_len, 0);
                length -= page_len;
                i++;
        }
        *sgl = sg;
        *nents = nent;
        return 0;

out:
        while (i > 0) {
                i--;
                __free_page(sg_page(&sg[i]));
        }
        kfree(sg);
        return -ENOMEM;
}
EXPORT_SYMBOL(target_alloc_sgl);

/*
 * 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.
 */
sense_reason_t
transport_generic_new_cmd(struct se_cmd *cmd)
{
        int ret = 0;
        bool zero_flag = !(cmd->se_cmd_flags & SCF_SCSI_DATA_CDB);

        if (cmd->prot_op != TARGET_PROT_NORMAL &&
            !(cmd->se_cmd_flags & SCF_PASSTHROUGH_PROT_SG_TO_MEM_NOALLOC)) {
                ret = target_alloc_sgl(&cmd->t_prot_sg, &cmd->t_prot_nents,
                                       cmd->prot_length, true, false);
                if (ret < 0)
                        return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
        }

        /*
         * 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) {

                if ((cmd->se_cmd_flags & SCF_BIDI) ||
                    (cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE)) {
                        u32 bidi_length;

                        if (cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE)
                                bidi_length = cmd->t_task_nolb *
                                              cmd->se_dev->dev_attrib.block_size;
                        else
                                bidi_length = cmd->data_length;

                        ret = target_alloc_sgl(&cmd->t_bidi_data_sg,
                                               &cmd->t_bidi_data_nents,
                                               bidi_length, zero_flag, false);
                        if (ret < 0)
                                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                }

                ret = target_alloc_sgl(&cmd->t_data_sg, &cmd->t_data_nents,
                                       cmd->data_length, zero_flag, false);
                if (ret < 0)
                        return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
        } else if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) &&
                    cmd->data_length) {
                /*
                 * Special case for COMPARE_AND_WRITE with fabrics
                 * using SCF_PASSTHROUGH_SG_TO_MEM_NOALLOC.
                 */
                u32 caw_length = cmd->t_task_nolb *
                                 cmd->se_dev->dev_attrib.block_size;

                ret = target_alloc_sgl(&cmd->t_bidi_data_sg,
                                       &cmd->t_bidi_data_nents,
                                       caw_length, zero_flag, false);
                if (ret < 0)
                        return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
        }
        /*
         * 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 || cmd->data_length == 0) {
                target_execute_cmd(cmd);
                return 0;
        }
        transport_cmd_check_stop(cmd, false, true);

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

        /* fabric drivers should only return -EAGAIN or -ENOMEM as error */
        WARN_ON(ret);

        return (!ret) ? 0 : TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

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);
        }
}

static bool
__transport_wait_for_tasks(struct se_cmd *, bool, bool *, bool *,
                           unsigned long *flags);

static void target_wait_free_cmd(struct se_cmd *cmd, bool *aborted, bool *tas)
{
        unsigned long flags;

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        __transport_wait_for_tasks(cmd, true, aborted, tas, &flags);
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);
}

int transport_generic_free_cmd(struct se_cmd *cmd, int wait_for_tasks)
{
        int ret = 0;
        bool aborted = false, tas = false;

        if (!(cmd->se_cmd_flags & SCF_SE_LUN_CMD)) {
                if (wait_for_tasks && (cmd->se_cmd_flags & SCF_SCSI_TMR_CDB))
                        target_wait_free_cmd(cmd, &aborted, &tas);

                if (!aborted || tas)
                        ret = transport_put_cmd(cmd);
        } else {
                if (wait_for_tasks)
                        target_wait_free_cmd(cmd, &aborted, &tas);
                /*
                 * Handle WRITE failure case where transport_generic_new_cmd()
                 * has already added se_cmd to state_list, but fabric has
                 * failed command before I/O submission.
                 */
                if (cmd->state_active)
                        target_remove_from_state_list(cmd);

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

                if (!aborted || tas)
                        ret = transport_put_cmd(cmd);
        }
        /*
         * If the task has been internally aborted due to TMR ABORT_TASK
         * or LUN_RESET, target_core_tmr.c is responsible for performing
         * the remaining calls to target_put_sess_cmd(), and not the
         * callers of this function.
         */
        if (aborted) {
                pr_debug("Detected CMD_T_ABORTED for ITT: %llu\n", cmd->tag);
                wait_for_completion(&cmd->cmd_wait_comp);
                cmd->se_tfo->release_cmd(cmd);
                ret = 1;
        }
        return ret;
}
EXPORT_SYMBOL(transport_generic_free_cmd);

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

        /*
         * 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) {
                if (!kref_get_unless_zero(&se_cmd->cmd_kref))
                        return -EINVAL;

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

        if (ret && ack_kref)
                target_put_sess_cmd(se_cmd);

        return ret;
}
EXPORT_SYMBOL(target_get_sess_cmd);

static void target_free_cmd_mem(struct se_cmd *cmd)
{
        transport_free_pages(cmd);

        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);
}

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;
        bool fabric_stop;

        spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);

        spin_lock(&se_cmd->t_state_lock);
        fabric_stop = (se_cmd->transport_state & CMD_T_FABRIC_STOP) &&
                      (se_cmd->transport_state & CMD_T_ABORTED);
        spin_unlock(&se_cmd->t_state_lock);

        if (se_cmd->cmd_wait_set || fabric_stop) {
                list_del_init(&se_cmd->se_cmd_list);
                spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
                target_free_cmd_mem(se_cmd);
                complete(&se_cmd->cmd_wait_comp);
                return;
        }
        list_del_init(&se_cmd->se_cmd_list);
        spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);

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

/* target_put_sess_cmd - Check for active I/O shutdown via kref_put
 * @se_cmd:     command descriptor to drop
 */
int target_put_sess_cmd(struct se_cmd *se_cmd)
{
        struct se_session *se_sess = se_cmd->se_sess;

        if (!se_sess) {
                target_free_cmd_mem(se_cmd);
                se_cmd->se_tfo->release_cmd(se_cmd);
                return 1;
        }
        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, *tmp_cmd;
        unsigned long flags;
        int rc;

        spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
        if (se_sess->sess_tearing_down) {
                spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
                return;
        }
        se_sess->sess_tearing_down = 1;
        list_splice_init(&se_sess->sess_cmd_list, &se_sess->sess_wait_list);

        list_for_each_entry_safe(se_cmd, tmp_cmd,
                                 &se_sess->sess_wait_list, se_cmd_list) {
                rc = kref_get_unless_zero(&se_cmd->cmd_kref);
                if (rc) {
                        se_cmd->cmd_wait_set = 1;
                        spin_lock(&se_cmd->t_state_lock);
                        se_cmd->transport_state |= CMD_T_FABRIC_STOP;
                        spin_unlock(&se_cmd->t_state_lock);
                } else
                        list_del_init(&se_cmd->se_cmd_list);
        }

        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
 */
void target_wait_for_sess_cmds(struct se_session *se_sess)
{
        struct se_cmd *se_cmd, *tmp_cmd;
        unsigned long flags;
        bool tas;

        list_for_each_entry_safe(se_cmd, tmp_cmd,
                                &se_sess->sess_wait_list, 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));

                spin_lock_irqsave(&se_cmd->t_state_lock, flags);
                tas = (se_cmd->transport_state & CMD_T_TAS);
                spin_unlock_irqrestore(&se_cmd->t_state_lock, flags);

                if (!target_put_sess_cmd(se_cmd)) {
                        if (tas)
                                target_put_sess_cmd(se_cmd);
                }

                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);
        }

        spin_lock_irqsave(&se_sess->sess_cmd_lock, flags);
        WARN_ON(!list_empty(&se_sess->sess_cmd_list));
        spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);

}
EXPORT_SYMBOL(target_wait_for_sess_cmds);

void transport_clear_lun_ref(struct se_lun *lun)
{
        percpu_ref_kill(&lun->lun_ref);
        wait_for_completion(&lun->lun_ref_comp);
}

static bool
__transport_wait_for_tasks(struct se_cmd *cmd, bool fabric_stop,
                           bool *aborted, bool *tas, unsigned long *flags)
        __releases(&cmd->t_state_lock)
        __acquires(&cmd->t_state_lock)
{

        assert_spin_locked(&cmd->t_state_lock);
        WARN_ON_ONCE(!irqs_disabled());

        if (fabric_stop)
                cmd->transport_state |= CMD_T_FABRIC_STOP;

        if (cmd->transport_state & CMD_T_ABORTED)
                *aborted = true;

        if (cmd->transport_state & CMD_T_TAS)
                *tas = true;

        if (!(cmd->se_cmd_flags & SCF_SE_LUN_CMD) &&
            !(cmd->se_cmd_flags & SCF_SCSI_TMR_CDB))
                return false;

        if (!(cmd->se_cmd_flags & SCF_SUPPORTED_SAM_OPCODE) &&
            !(cmd->se_cmd_flags & SCF_SCSI_TMR_CDB))
                return false;

        if (!(cmd->transport_state & CMD_T_ACTIVE))
                return false;

        if (fabric_stop && *aborted)
                return false;

        cmd->transport_state |= CMD_T_STOP;

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

        return true;
}

/**
 * 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;
        bool ret, aborted = false, tas = false;

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        ret = __transport_wait_for_tasks(cmd, false, &aborted, &tas, &flags);
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);

        return ret;
}
EXPORT_SYMBOL(transport_wait_for_tasks);

struct sense_info {
        u8 key;
        u8 asc;
        u8 ascq;
        bool add_sector_info;
};

static const struct sense_info sense_info_table[] = {
        [TCM_NO_SENSE] = {
                .key = NOT_READY
        },
        [TCM_NON_EXISTENT_LUN] = {
                .key = ILLEGAL_REQUEST,
                .asc = 0x25 /* LOGICAL UNIT NOT SUPPORTED */
        },
        [TCM_UNSUPPORTED_SCSI_OPCODE] = {
                .key = ILLEGAL_REQUEST,
                .asc = 0x20, /* INVALID COMMAND OPERATION CODE */
        },
        [TCM_SECTOR_COUNT_TOO_MANY] = {
                .key = ILLEGAL_REQUEST,
                .asc = 0x20, /* INVALID COMMAND OPERATION CODE */
        },
        [TCM_UNKNOWN_MODE_PAGE] = {
                .key = ILLEGAL_REQUEST,
                .asc = 0x24, /* INVALID FIELD IN CDB */
        },
        [TCM_CHECK_CONDITION_ABORT_CMD] = {
                .key = ABORTED_COMMAND,
                .asc = 0x29, /* BUS DEVICE RESET FUNCTION OCCURRED */
                .ascq = 0x03,
        },
        [TCM_INCORRECT_AMOUNT_OF_DATA] = {
                .key = ABORTED_COMMAND,
                .asc = 0x0c, /* WRITE ERROR */
                .ascq = 0x0d, /* NOT ENOUGH UNSOLICITED DATA */
        },
        [TCM_INVALID_CDB_FIELD] = {
                .key = ILLEGAL_REQUEST,
                .asc = 0x24, /* INVALID FIELD IN CDB */
        },
        [TCM_INVALID_PARAMETER_LIST] = {
                .key = ILLEGAL_REQUEST,
                .asc = 0x26, /* INVALID FIELD IN PARAMETER LIST */
        },
        [TCM_PARAMETER_LIST_LENGTH_ERROR] = {
                .key = ILLEGAL_REQUEST,
                .asc = 0x1a, /* PARAMETER LIST LENGTH ERROR */
        },
        [TCM_UNEXPECTED_UNSOLICITED_DATA] = {
                .key = ILLEGAL_REQUEST,
                .asc = 0x0c, /* WRITE ERROR */
                .ascq = 0x0c, /* UNEXPECTED_UNSOLICITED_DATA */
        },
        [TCM_SERVICE_CRC_ERROR] = {
                .key = ABORTED_COMMAND,
                .asc = 0x47, /* PROTOCOL SERVICE CRC ERROR */
                .ascq = 0x05, /* N/A */
        },
        [TCM_SNACK_REJECTED] = {
                .key = ABORTED_COMMAND,
                .asc = 0x11, /* READ ERROR */
                .ascq = 0x13, /* FAILED RETRANSMISSION REQUEST */
        },
        [TCM_WRITE_PROTECTED] = {
                .key = DATA_PROTECT,
                .asc = 0x27, /* WRITE PROTECTED */
        },
        [TCM_ADDRESS_OUT_OF_RANGE] = {
                .key = ILLEGAL_REQUEST,
                .asc = 0x21, /* LOGICAL BLOCK ADDRESS OUT OF RANGE */
        },
        [TCM_CHECK_CONDITION_UNIT_ATTENTION] = {
                .key = UNIT_ATTENTION,
        },
        [TCM_CHECK_CONDITION_NOT_READY] = {
                .key = NOT_READY,
        },
        [TCM_MISCOMPARE_VERIFY] = {
                .key = MISCOMPARE,
                .asc = 0x1d, /* MISCOMPARE DURING VERIFY OPERATION */
                .ascq = 0x00,
        },
        [TCM_LOGICAL_BLOCK_GUARD_CHECK_FAILED] = {
                .key = ABORTED_COMMAND,
                .asc = 0x10,
                .ascq = 0x01, /* LOGICAL BLOCK GUARD CHECK FAILED */
                .add_sector_info = true,
        },
        [TCM_LOGICAL_BLOCK_APP_TAG_CHECK_FAILED] = {
                .key = ABORTED_COMMAND,
                .asc = 0x10,
                .ascq = 0x02, /* LOGICAL BLOCK APPLICATION TAG CHECK FAILED */
                .add_sector_info = true,
        },
        [TCM_LOGICAL_BLOCK_REF_TAG_CHECK_FAILED] = {
                .key = ABORTED_COMMAND,
                .asc = 0x10,
                .ascq = 0x03, /* LOGICAL BLOCK REFERENCE TAG CHECK FAILED */
                .add_sector_info = true,
        },
        [TCM_COPY_TARGET_DEVICE_NOT_REACHABLE] = {
                .key = COPY_ABORTED,
                .asc = 0x0d,
                .ascq = 0x02, /* COPY TARGET DEVICE NOT REACHABLE */

        },
        [TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE] = {
                /*
                 * Returning ILLEGAL REQUEST would cause immediate IO errors on
                 * Solaris initiators.  Returning NOT READY instead means the
                 * operations will be retried a finite number of times and we
                 * can survive intermittent errors.
                 */
                .key = NOT_READY,
                .asc = 0x08, /* LOGICAL UNIT COMMUNICATION FAILURE */
        },
};

static int translate_sense_reason(struct se_cmd *cmd, sense_reason_t reason)
{
        const struct sense_info *si;
        u8 *buffer = cmd->sense_buffer;
        int r = (__force int)reason;
        u8 asc, ascq;
        bool desc_format = target_sense_desc_format(cmd->se_dev);

        if (r < ARRAY_SIZE(sense_info_table) && sense_info_table[r].key)
                si = &sense_info_table[r];
        else
                si = &sense_info_table[(__force int)
                                       TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE];

        if (reason == TCM_CHECK_CONDITION_UNIT_ATTENTION) {
                core_scsi3_ua_for_check_condition(cmd, &asc, &ascq);
                WARN_ON_ONCE(asc == 0);
        } else if (si->asc == 0) {
                WARN_ON_ONCE(cmd->scsi_asc == 0);
                asc = cmd->scsi_asc;
                ascq = cmd->scsi_ascq;
        } else {
                asc = si->asc;
                ascq = si->ascq;
        }

        scsi_build_sense_buffer(desc_format, buffer, si->key, asc, ascq);
        if (si->add_sector_info)
                return scsi_set_sense_information(buffer,
                                                  cmd->scsi_sense_length,
                                                  cmd->bad_sector);

        return 0;
}

int
transport_send_check_condition_and_sense(struct se_cmd *cmd,
                sense_reason_t reason, int from_transport)
{
        unsigned long flags;

        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 (!from_transport) {
                int rc;

                cmd->se_cmd_flags |= SCF_EMULATED_TASK_SENSE;
                cmd->scsi_status = SAM_STAT_CHECK_CONDITION;
                cmd->scsi_sense_length  = TRANSPORT_SENSE_BUFFER;
                rc = translate_sense_reason(cmd, reason);
                if (rc)
                        return rc;
        }

        trace_target_cmd_complete(cmd);
        return cmd->se_tfo->queue_status(cmd);
}
EXPORT_SYMBOL(transport_send_check_condition_and_sense);

static int __transport_check_aborted_status(struct se_cmd *cmd, int send_status)
        __releases(&cmd->t_state_lock)
        __acquires(&cmd->t_state_lock)
{
        assert_spin_locked(&cmd->t_state_lock);
        WARN_ON_ONCE(!irqs_disabled());

        if (!(cmd->transport_state & CMD_T_ABORTED))
                return 0;
        /*
         * If cmd has been aborted but either no status is to be sent or it has
         * already been sent, just return
         */
        if (!send_status || !(cmd->se_cmd_flags & SCF_SEND_DELAYED_TAS)) {
                if (send_status)
                        cmd->se_cmd_flags |= SCF_SEND_DELAYED_TAS;
                return 1;
        }

        pr_debug("Sending delayed SAM_STAT_TASK_ABORTED status for CDB:"
                " 0x%02x ITT: 0x%08llx\n", cmd->t_task_cdb[0], cmd->tag);

        cmd->se_cmd_flags &= ~SCF_SEND_DELAYED_TAS;
        cmd->scsi_status = SAM_STAT_TASK_ABORTED;
        trace_target_cmd_complete(cmd);

        spin_unlock_irq(&cmd->t_state_lock);
        cmd->se_tfo->queue_status(cmd);
        spin_lock_irq(&cmd->t_state_lock);

        return 1;
}

int transport_check_aborted_status(struct se_cmd *cmd, int send_status)
{
        int ret;

        spin_lock_irq(&cmd->t_state_lock);
        ret = __transport_check_aborted_status(cmd, send_status);
        spin_unlock_irq(&cmd->t_state_lock);

        return ret;
}
EXPORT_SYMBOL(transport_check_aborted_status);

void transport_send_task_abort(struct se_cmd *cmd)
{
        unsigned long flags;

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

        /*
         * If there are still expected incoming fabric WRITEs, we wait
         * until until they have completed before sending a TASK_ABORTED
         * response.  This response with TASK_ABORTED status will be
         * queued back to fabric module by transport_check_aborted_status().
         */
        if (cmd->data_direction == DMA_TO_DEVICE) {
                if (cmd->se_tfo->write_pending_status(cmd) != 0) {
                        spin_lock_irqsave(&cmd->t_state_lock, flags);
                        if (cmd->se_cmd_flags & SCF_SEND_DELAYED_TAS) {
                                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                                goto send_abort;
                        }
                        cmd->se_cmd_flags |= SCF_SEND_DELAYED_TAS;
                        spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                        return;
                }
        }
send_abort:
        cmd->scsi_status = SAM_STAT_TASK_ABORTED;

        transport_lun_remove_cmd(cmd);

        pr_debug("Setting SAM_STAT_TASK_ABORTED status for CDB: 0x%02x, ITT: 0x%08llx\n",
                 cmd->t_task_cdb[0], cmd->tag);

        trace_target_cmd_complete(cmd);
        cmd->se_tfo->queue_status(cmd);
}

static void target_tmr_work(struct work_struct *work)
{
        struct se_cmd *cmd = container_of(work, struct se_cmd, work);
        struct se_device *dev = cmd->se_dev;
        struct se_tmr_req *tmr = cmd->se_tmr_req;
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        if (cmd->transport_state & CMD_T_ABORTED) {
                tmr->response = TMR_FUNCTION_REJECTED;
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                goto check_stop;
        }
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);

        switch (tmr->function) {
        case TMR_ABORT_TASK:
                core_tmr_abort_task(dev, tmr, cmd->se_sess);
                break;
        case TMR_ABORT_TASK_SET:
        case TMR_CLEAR_ACA:
        case TMR_CLEAR_TASK_SET:
                tmr->response = TMR_TASK_MGMT_FUNCTION_NOT_SUPPORTED;
                break;
        case TMR_LUN_RESET:
                ret = core_tmr_lun_reset(dev, tmr, NULL, NULL);
                tmr->response = (!ret) ? TMR_FUNCTION_COMPLETE :
                                         TMR_FUNCTION_REJECTED;
                if (tmr->response == TMR_FUNCTION_COMPLETE) {
                        target_ua_allocate_lun(cmd->se_sess->se_node_acl,
                                               cmd->orig_fe_lun, 0x29,
                                               ASCQ_29H_BUS_DEVICE_RESET_FUNCTION_OCCURRED);
                }
                break;
        case TMR_TARGET_WARM_RESET:
                tmr->response = TMR_FUNCTION_REJECTED;
                break;
        case TMR_TARGET_COLD_RESET:
                tmr->response = TMR_FUNCTION_REJECTED;
                break;
        default:
                pr_err("Uknown TMR function: 0x%02x.\n",
                                tmr->function);
                tmr->response = TMR_FUNCTION_REJECTED;
                break;
        }

        spin_lock_irqsave(&cmd->t_state_lock, flags);
        if (cmd->transport_state & CMD_T_ABORTED) {
                spin_unlock_irqrestore(&cmd->t_state_lock, flags);
                goto check_stop;
        }
        cmd->t_state = TRANSPORT_ISTATE_PROCESSING;
        spin_unlock_irqrestore(&cmd->t_state_lock, flags);

        cmd->se_tfo->queue_tm_rsp(cmd);

check_stop:
        transport_cmd_check_stop_to_fabric(cmd);
}

int transport_generic_handle_tmr(
        struct se_cmd *cmd)
{
        unsigned long flags;

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

        INIT_WORK(&cmd->work, target_tmr_work);
        queue_work(cmd->se_dev->tmr_wq, &cmd->work);
        return 0;
}
EXPORT_SYMBOL(transport_generic_handle_tmr);

bool
target_check_wce(struct se_device *dev)
{
        bool wce = false;

        if (dev->transport->get_write_cache)
                wce = dev->transport->get_write_cache(dev);
        else if (dev->dev_attrib.emulate_write_cache > 0)
                wce = true;

        return wce;
}

bool
target_check_fua(struct se_device *dev)
{
        return target_check_wce(dev) && dev->dev_attrib.emulate_fua_write > 0;
}