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

#include <linux/string.h>
#include <linux/parser.h>
#include <linux/timer.h>
#include <linux/blkdev.h>
#include <linux/blk_types.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/genhd.h>
#include <linux/cdrom.h>
#include <linux/file.h>
#include <linux/module.h>
#include <scsi/scsi.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_tcq.h>

#include <target/target_core_base.h>
#include <target/target_core_device.h>
#include <target/target_core_transport.h>

#include "target_core_pscsi.h"

#define ISPRINT(a)  ((a >= ' ') && (a <= '~'))

static struct se_subsystem_api pscsi_template;

static void pscsi_req_done(struct request *, int);

/*      pscsi_attach_hba():
 *
 *      pscsi_get_sh() used scsi_host_lookup() to locate struct Scsi_Host.
 *      from the passed SCSI Host ID.
 */
static int pscsi_attach_hba(struct se_hba *hba, u32 host_id)
{
        struct pscsi_hba_virt *phv;

        phv = kzalloc(sizeof(struct pscsi_hba_virt), GFP_KERNEL);
        if (!phv) {
                pr_err("Unable to allocate struct pscsi_hba_virt\n");
                return -ENOMEM;
        }
        phv->phv_host_id = host_id;
        phv->phv_mode = PHV_VIRUTAL_HOST_ID;

        hba->hba_ptr = phv;

        pr_debug("CORE_HBA[%d] - TCM SCSI HBA Driver %s on"
                " Generic Target Core Stack %s\n", hba->hba_id,
                PSCSI_VERSION, TARGET_CORE_MOD_VERSION);
        pr_debug("CORE_HBA[%d] - Attached SCSI HBA to Generic\n",
               hba->hba_id);

        return 0;
}

static void pscsi_detach_hba(struct se_hba *hba)
{
        struct pscsi_hba_virt *phv = hba->hba_ptr;
        struct Scsi_Host *scsi_host = phv->phv_lld_host;

        if (scsi_host) {
                scsi_host_put(scsi_host);

                pr_debug("CORE_HBA[%d] - Detached SCSI HBA: %s from"
                        " Generic Target Core\n", hba->hba_id,
                        (scsi_host->hostt->name) ? (scsi_host->hostt->name) :
                        "Unknown");
        } else
                pr_debug("CORE_HBA[%d] - Detached Virtual SCSI HBA"
                        " from Generic Target Core\n", hba->hba_id);

        kfree(phv);
        hba->hba_ptr = NULL;
}

static int pscsi_pmode_enable_hba(struct se_hba *hba, unsigned long mode_flag)
{
        struct pscsi_hba_virt *phv = (struct pscsi_hba_virt *)hba->hba_ptr;
        struct Scsi_Host *sh = phv->phv_lld_host;
        /*
         * Release the struct Scsi_Host
         */
        if (!mode_flag) {
                if (!sh)
                        return 0;

                phv->phv_lld_host = NULL;
                phv->phv_mode = PHV_VIRUTAL_HOST_ID;

                pr_debug("CORE_HBA[%d] - Disabled pSCSI HBA Passthrough"
                        " %s\n", hba->hba_id, (sh->hostt->name) ?
                        (sh->hostt->name) : "Unknown");

                scsi_host_put(sh);
                return 0;
        }
        /*
         * Otherwise, locate struct Scsi_Host from the original passed
         * pSCSI Host ID and enable for phba mode
         */
        sh = scsi_host_lookup(phv->phv_host_id);
        if (!sh) {
                pr_err("pSCSI: Unable to locate SCSI Host for"
                        " phv_host_id: %d\n", phv->phv_host_id);
                return -EINVAL;
        }

        phv->phv_lld_host = sh;
        phv->phv_mode = PHV_LLD_SCSI_HOST_NO;

        pr_debug("CORE_HBA[%d] - Enabled pSCSI HBA Passthrough %s\n",
                hba->hba_id, (sh->hostt->name) ? (sh->hostt->name) : "Unknown");

        return 1;
}

static void pscsi_tape_read_blocksize(struct se_device *dev,
                struct scsi_device *sdev)
{
        unsigned char cdb[MAX_COMMAND_SIZE], *buf;
        int ret;

        buf = kzalloc(12, GFP_KERNEL);
        if (!buf)
                return;

        memset(cdb, 0, MAX_COMMAND_SIZE);
        cdb[0] = MODE_SENSE;
        cdb[4] = 0x0c; /* 12 bytes */

        ret = scsi_execute_req(sdev, cdb, DMA_FROM_DEVICE, buf, 12, NULL,
                        HZ, 1, NULL);
        if (ret)
                goto out_free;

        /*
         * If MODE_SENSE still returns zero, set the default value to 1024.
         */
        sdev->sector_size = (buf[9] << 16) | (buf[10] << 8) | (buf[11]);
        if (!sdev->sector_size)
                sdev->sector_size = 1024;
out_free:
        kfree(buf);
}

static void
pscsi_set_inquiry_info(struct scsi_device *sdev, struct t10_wwn *wwn)
{
        unsigned char *buf;

        if (sdev->inquiry_len < INQUIRY_LEN)
                return;

        buf = sdev->inquiry;
        if (!buf)
                return;
        /*
         * Use sdev->inquiry from drivers/scsi/scsi_scan.c:scsi_alloc_sdev()
         */
        memcpy(&wwn->vendor[0], &buf[8], sizeof(wwn->vendor));
        memcpy(&wwn->model[0], &buf[16], sizeof(wwn->model));
        memcpy(&wwn->revision[0], &buf[32], sizeof(wwn->revision));
}

static int
pscsi_get_inquiry_vpd_serial(struct scsi_device *sdev, struct t10_wwn *wwn)
{
        unsigned char cdb[MAX_COMMAND_SIZE], *buf;
        int ret;

        buf = kzalloc(INQUIRY_VPD_SERIAL_LEN, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        memset(cdb, 0, MAX_COMMAND_SIZE);
        cdb[0] = INQUIRY;
        cdb[1] = 0x01; /* Query VPD */
        cdb[2] = 0x80; /* Unit Serial Number */
        cdb[3] = (INQUIRY_VPD_SERIAL_LEN >> 8) & 0xff;
        cdb[4] = (INQUIRY_VPD_SERIAL_LEN & 0xff);

        ret = scsi_execute_req(sdev, cdb, DMA_FROM_DEVICE, buf,
                              INQUIRY_VPD_SERIAL_LEN, NULL, HZ, 1, NULL);
        if (ret)
                goto out_free;

        snprintf(&wwn->unit_serial[0], INQUIRY_VPD_SERIAL_LEN, "%s", &buf[4]);

        wwn->t10_sub_dev->su_dev_flags |= SDF_FIRMWARE_VPD_UNIT_SERIAL;

        kfree(buf);
        return 0;

out_free:
        kfree(buf);
        return -EPERM;
}

static void
pscsi_get_inquiry_vpd_device_ident(struct scsi_device *sdev,
                struct t10_wwn *wwn)
{
        unsigned char cdb[MAX_COMMAND_SIZE], *buf, *page_83;
        int ident_len, page_len, off = 4, ret;
        struct t10_vpd *vpd;

        buf = kzalloc(INQUIRY_VPD_SERIAL_LEN, GFP_KERNEL);
        if (!buf)
                return;

        memset(cdb, 0, MAX_COMMAND_SIZE);
        cdb[0] = INQUIRY;
        cdb[1] = 0x01; /* Query VPD */
        cdb[2] = 0x83; /* Device Identifier */
        cdb[3] = (INQUIRY_VPD_DEVICE_IDENTIFIER_LEN >> 8) & 0xff;
        cdb[4] = (INQUIRY_VPD_DEVICE_IDENTIFIER_LEN & 0xff);

        ret = scsi_execute_req(sdev, cdb, DMA_FROM_DEVICE, buf,
                              INQUIRY_VPD_DEVICE_IDENTIFIER_LEN,
                              NULL, HZ, 1, NULL);
        if (ret)
                goto out;

        page_len = (buf[2] << 8) | buf[3];
        while (page_len > 0) {
                /* Grab a pointer to the Identification descriptor */
                page_83 = &buf[off];
                ident_len = page_83[3];
                if (!ident_len) {
                        pr_err("page_83[3]: identifier"
                                        " length zero!\n");
                        break;
                }
                pr_debug("T10 VPD Identifer Length: %d\n", ident_len);

                vpd = kzalloc(sizeof(struct t10_vpd), GFP_KERNEL);
                if (!vpd) {
                        pr_err("Unable to allocate memory for"
                                        " struct t10_vpd\n");
                        goto out;
                }
                INIT_LIST_HEAD(&vpd->vpd_list);

                transport_set_vpd_proto_id(vpd, page_83);
                transport_set_vpd_assoc(vpd, page_83);

                if (transport_set_vpd_ident_type(vpd, page_83) < 0) {
                        off += (ident_len + 4);
                        page_len -= (ident_len + 4);
                        kfree(vpd);
                        continue;
                }
                if (transport_set_vpd_ident(vpd, page_83) < 0) {
                        off += (ident_len + 4);
                        page_len -= (ident_len + 4);
                        kfree(vpd);
                        continue;
                }

                list_add_tail(&vpd->vpd_list, &wwn->t10_vpd_list);
                off += (ident_len + 4);
                page_len -= (ident_len + 4);
        }

out:
        kfree(buf);
}

/*      pscsi_add_device_to_list():
 *
 *
 */
static struct se_device *pscsi_add_device_to_list(
        struct se_hba *hba,
        struct se_subsystem_dev *se_dev,
        struct pscsi_dev_virt *pdv,
        struct scsi_device *sd,
        int dev_flags)
{
        struct se_device *dev;
        struct se_dev_limits dev_limits;
        struct request_queue *q;
        struct queue_limits *limits;

        memset(&dev_limits, 0, sizeof(struct se_dev_limits));

        if (!sd->queue_depth) {
                sd->queue_depth = PSCSI_DEFAULT_QUEUEDEPTH;

                pr_err("Set broken SCSI Device %d:%d:%d"
                        " queue_depth to %d\n", sd->channel, sd->id,
                                sd->lun, sd->queue_depth);
        }
        /*
         * Setup the local scope queue_limits from struct request_queue->limits
         * to pass into transport_add_device_to_core_hba() as struct se_dev_limits.
         */
        q = sd->request_queue;
        limits = &dev_limits.limits;
        limits->logical_block_size = sd->sector_size;
        limits->max_hw_sectors = min_t(int, sd->host->max_sectors, queue_max_hw_sectors(q));
        limits->max_sectors = min_t(int, sd->host->max_sectors, queue_max_sectors(q));
        dev_limits.hw_queue_depth = sd->queue_depth;
        dev_limits.queue_depth = sd->queue_depth;
        /*
         * Setup our standard INQUIRY info into se_dev->t10_wwn
         */
        pscsi_set_inquiry_info(sd, &se_dev->t10_wwn);

        /*
         * Set the pointer pdv->pdv_sd to from passed struct scsi_device,
         * which has already been referenced with Linux SCSI code with
         * scsi_device_get() in this file's pscsi_create_virtdevice().
         *
         * The passthrough operations called by the transport_add_device_*
         * function below will require this pointer to be set for passthroug
         *  ops.
         *
         * For the shutdown case in pscsi_free_device(), this struct
         * scsi_device  reference is released with Linux SCSI code
         * scsi_device_put() and the pdv->pdv_sd cleared.
         */
        pdv->pdv_sd = sd;

        dev = transport_add_device_to_core_hba(hba, &pscsi_template,
                                se_dev, dev_flags, pdv,
                                &dev_limits, NULL, NULL);
        if (!dev) {
                pdv->pdv_sd = NULL;
                return NULL;
        }

        /*
         * Locate VPD WWN Information used for various purposes within
         * the Storage Engine.
         */
        if (!pscsi_get_inquiry_vpd_serial(sd, &se_dev->t10_wwn)) {
                /*
                 * If VPD Unit Serial returned GOOD status, try
                 * VPD Device Identification page (0x83).
                 */
                pscsi_get_inquiry_vpd_device_ident(sd, &se_dev->t10_wwn);
        }

        /*
         * For TYPE_TAPE, attempt to determine blocksize with MODE_SENSE.
         */
        if (sd->type == TYPE_TAPE)
                pscsi_tape_read_blocksize(dev, sd);
        return dev;
}

static void *pscsi_allocate_virtdevice(struct se_hba *hba, const char *name)
{
        struct pscsi_dev_virt *pdv;

        pdv = kzalloc(sizeof(struct pscsi_dev_virt), GFP_KERNEL);
        if (!pdv) {
                pr_err("Unable to allocate memory for struct pscsi_dev_virt\n");
                return NULL;
        }
        pdv->pdv_se_hba = hba;

        pr_debug("PSCSI: Allocated pdv: %p for %s\n", pdv, name);
        return pdv;
}

/*
 * Called with struct Scsi_Host->host_lock called.
 */
static struct se_device *pscsi_create_type_disk(
        struct scsi_device *sd,
        struct pscsi_dev_virt *pdv,
        struct se_subsystem_dev *se_dev,
        struct se_hba *hba)
        __releases(sh->host_lock)
{
        struct se_device *dev;
        struct pscsi_hba_virt *phv = (struct pscsi_hba_virt *)pdv->pdv_se_hba->hba_ptr;
        struct Scsi_Host *sh = sd->host;
        struct block_device *bd;
        u32 dev_flags = 0;

        if (scsi_device_get(sd)) {
                pr_err("scsi_device_get() failed for %d:%d:%d:%d\n",
                        sh->host_no, sd->channel, sd->id, sd->lun);
                spin_unlock_irq(sh->host_lock);
                return NULL;
        }
        spin_unlock_irq(sh->host_lock);
        /*
         * Claim exclusive struct block_device access to struct scsi_device
         * for TYPE_DISK using supplied udev_path
         */
        bd = blkdev_get_by_path(se_dev->se_dev_udev_path,
                                FMODE_WRITE|FMODE_READ|FMODE_EXCL, pdv);
        if (IS_ERR(bd)) {
                pr_err("pSCSI: blkdev_get_by_path() failed\n");
                scsi_device_put(sd);
                return NULL;
        }
        pdv->pdv_bd = bd;

        dev = pscsi_add_device_to_list(hba, se_dev, pdv, sd, dev_flags);
        if (!dev) {
                blkdev_put(pdv->pdv_bd, FMODE_WRITE|FMODE_READ|FMODE_EXCL);
                scsi_device_put(sd);
                return NULL;
        }
        pr_debug("CORE_PSCSI[%d] - Added TYPE_DISK for %d:%d:%d:%d\n",
                phv->phv_host_id, sh->host_no, sd->channel, sd->id, sd->lun);

        return dev;
}

/*
 * Called with struct Scsi_Host->host_lock called.
 */
static struct se_device *pscsi_create_type_rom(
        struct scsi_device *sd,
        struct pscsi_dev_virt *pdv,
        struct se_subsystem_dev *se_dev,
        struct se_hba *hba)
        __releases(sh->host_lock)
{
        struct se_device *dev;
        struct pscsi_hba_virt *phv = (struct pscsi_hba_virt *)pdv->pdv_se_hba->hba_ptr;
        struct Scsi_Host *sh = sd->host;
        u32 dev_flags = 0;

        if (scsi_device_get(sd)) {
                pr_err("scsi_device_get() failed for %d:%d:%d:%d\n",
                        sh->host_no, sd->channel, sd->id, sd->lun);
                spin_unlock_irq(sh->host_lock);
                return NULL;
        }
        spin_unlock_irq(sh->host_lock);

        dev = pscsi_add_device_to_list(hba, se_dev, pdv, sd, dev_flags);
        if (!dev) {
                scsi_device_put(sd);
                return NULL;
        }
        pr_debug("CORE_PSCSI[%d] - Added Type: %s for %d:%d:%d:%d\n",
                phv->phv_host_id, scsi_device_type(sd->type), sh->host_no,
                sd->channel, sd->id, sd->lun);

        return dev;
}

/*
 *Called with struct Scsi_Host->host_lock called.
 */
static struct se_device *pscsi_create_type_other(
        struct scsi_device *sd,
        struct pscsi_dev_virt *pdv,
        struct se_subsystem_dev *se_dev,
        struct se_hba *hba)
        __releases(sh->host_lock)
{
        struct se_device *dev;
        struct pscsi_hba_virt *phv = (struct pscsi_hba_virt *)pdv->pdv_se_hba->hba_ptr;
        struct Scsi_Host *sh = sd->host;
        u32 dev_flags = 0;

        spin_unlock_irq(sh->host_lock);
        dev = pscsi_add_device_to_list(hba, se_dev, pdv, sd, dev_flags);
        if (!dev)
                return NULL;

        pr_debug("CORE_PSCSI[%d] - Added Type: %s for %d:%d:%d:%d\n",
                phv->phv_host_id, scsi_device_type(sd->type), sh->host_no,
                sd->channel, sd->id, sd->lun);

        return dev;
}

static struct se_device *pscsi_create_virtdevice(
        struct se_hba *hba,
        struct se_subsystem_dev *se_dev,
        void *p)
{
        struct pscsi_dev_virt *pdv = (struct pscsi_dev_virt *)p;
        struct se_device *dev;
        struct scsi_device *sd;
        struct pscsi_hba_virt *phv = (struct pscsi_hba_virt *)hba->hba_ptr;
        struct Scsi_Host *sh = phv->phv_lld_host;
        int legacy_mode_enable = 0;

        if (!pdv) {
                pr_err("Unable to locate struct pscsi_dev_virt"
                                " parameter\n");
                return ERR_PTR(-EINVAL);
        }
        /*
         * If not running in PHV_LLD_SCSI_HOST_NO mode, locate the
         * struct Scsi_Host we will need to bring the TCM/pSCSI object online
         */
        if (!sh) {
                if (phv->phv_mode == PHV_LLD_SCSI_HOST_NO) {
                        pr_err("pSCSI: Unable to locate struct"
                                " Scsi_Host for PHV_LLD_SCSI_HOST_NO\n");
                        return ERR_PTR(-ENODEV);
                }
                /*
                 * For the newer PHV_VIRUTAL_HOST_ID struct scsi_device
                 * reference, we enforce that udev_path has been set
                 */
                if (!(se_dev->su_dev_flags & SDF_USING_UDEV_PATH)) {
                        pr_err("pSCSI: udev_path attribute has not"
                                " been set before ENABLE=1\n");
                        return ERR_PTR(-EINVAL);
                }
                /*
                 * If no scsi_host_id= was passed for PHV_VIRUTAL_HOST_ID,
                 * use the original TCM hba ID to reference Linux/SCSI Host No
                 * and enable for PHV_LLD_SCSI_HOST_NO mode.
                 */
                if (!(pdv->pdv_flags & PDF_HAS_VIRT_HOST_ID)) {
                        spin_lock(&hba->device_lock);
                        if (!list_empty(&hba->hba_dev_list)) {
                                pr_err("pSCSI: Unable to set hba_mode"
                                        " with active devices\n");
                                spin_unlock(&hba->device_lock);
                                return ERR_PTR(-EEXIST);
                        }
                        spin_unlock(&hba->device_lock);

                        if (pscsi_pmode_enable_hba(hba, 1) != 1)
                                return ERR_PTR(-ENODEV);

                        legacy_mode_enable = 1;
                        hba->hba_flags |= HBA_FLAGS_PSCSI_MODE;
                        sh = phv->phv_lld_host;
                } else {
                        sh = scsi_host_lookup(pdv->pdv_host_id);
                        if (!sh) {
                                pr_err("pSCSI: Unable to locate"
                                        " pdv_host_id: %d\n", pdv->pdv_host_id);
                                return ERR_PTR(-EINVAL);
                        }
                        pdv->pdv_lld_host = sh;
                }
        } else {
                if (phv->phv_mode == PHV_VIRUTAL_HOST_ID) {
                        pr_err("pSCSI: PHV_VIRUTAL_HOST_ID set while"
                                " struct Scsi_Host exists\n");
                        return ERR_PTR(-EEXIST);
                }
        }

        spin_lock_irq(sh->host_lock);
        list_for_each_entry(sd, &sh->__devices, siblings) {
                if ((pdv->pdv_channel_id != sd->channel) ||
                    (pdv->pdv_target_id != sd->id) ||
                    (pdv->pdv_lun_id != sd->lun))
                        continue;
                /*
                 * Functions will release the held struct scsi_host->host_lock
                 * before calling calling pscsi_add_device_to_list() to register
                 * struct scsi_device with target_core_mod.
                 */
                switch (sd->type) {
                case TYPE_DISK:
                        dev = pscsi_create_type_disk(sd, pdv, se_dev, hba);
                        break;
                case TYPE_ROM:
                        dev = pscsi_create_type_rom(sd, pdv, se_dev, hba);
                        break;
                default:
                        dev = pscsi_create_type_other(sd, pdv, se_dev, hba);
                        break;
                }

                if (!dev) {
                        if (phv->phv_mode == PHV_VIRUTAL_HOST_ID)
                                scsi_host_put(sh);
                        else if (legacy_mode_enable) {
                                pscsi_pmode_enable_hba(hba, 0);
                                hba->hba_flags &= ~HBA_FLAGS_PSCSI_MODE;
                        }
                        pdv->pdv_sd = NULL;
                        return ERR_PTR(-ENODEV);
                }
                return dev;
        }
        spin_unlock_irq(sh->host_lock);

        pr_err("pSCSI: Unable to locate %d:%d:%d:%d\n", sh->host_no,
                pdv->pdv_channel_id,  pdv->pdv_target_id, pdv->pdv_lun_id);

        if (phv->phv_mode == PHV_VIRUTAL_HOST_ID)
                scsi_host_put(sh);
        else if (legacy_mode_enable) {
                pscsi_pmode_enable_hba(hba, 0);
                hba->hba_flags &= ~HBA_FLAGS_PSCSI_MODE;
        }

        return ERR_PTR(-ENODEV);
}

/*      pscsi_free_device(): (Part of se_subsystem_api_t template)
 *
 *
 */
static void pscsi_free_device(void *p)
{
        struct pscsi_dev_virt *pdv = p;
        struct pscsi_hba_virt *phv = pdv->pdv_se_hba->hba_ptr;
        struct scsi_device *sd = pdv->pdv_sd;

        if (sd) {
                /*
                 * Release exclusive pSCSI internal struct block_device claim for
                 * struct scsi_device with TYPE_DISK from pscsi_create_type_disk()
                 */
                if ((sd->type == TYPE_DISK) && pdv->pdv_bd) {
                        blkdev_put(pdv->pdv_bd,
                                   FMODE_WRITE|FMODE_READ|FMODE_EXCL);
                        pdv->pdv_bd = NULL;
                }
                /*
                 * For HBA mode PHV_LLD_SCSI_HOST_NO, release the reference
                 * to struct Scsi_Host now.
                 */
                if ((phv->phv_mode == PHV_LLD_SCSI_HOST_NO) &&
                    (phv->phv_lld_host != NULL))
                        scsi_host_put(phv->phv_lld_host);
                else if (pdv->pdv_lld_host)
                        scsi_host_put(pdv->pdv_lld_host);

                if ((sd->type == TYPE_DISK) || (sd->type == TYPE_ROM))
                        scsi_device_put(sd);

                pdv->pdv_sd = NULL;
        }

        kfree(pdv);
}

static inline struct pscsi_plugin_task *PSCSI_TASK(struct se_task *task)
{
        return container_of(task, struct pscsi_plugin_task, pscsi_task);
}


/*      pscsi_transport_complete():
 *
 *
 */
static int pscsi_transport_complete(struct se_task *task)
{
        struct pscsi_dev_virt *pdv = task->task_se_cmd->se_dev->dev_ptr;
        struct scsi_device *sd = pdv->pdv_sd;
        int result;
        struct pscsi_plugin_task *pt = PSCSI_TASK(task);
        unsigned char *cdb = &pt->pscsi_cdb[0];

        result = pt->pscsi_result;
        /*
         * Hack to make sure that Write-Protect modepage is set if R/O mode is
         * forced.
         */
        if (((cdb[0] == MODE_SENSE) || (cdb[0] == MODE_SENSE_10)) &&
             (status_byte(result) << 1) == SAM_STAT_GOOD) {
                if (!task->task_se_cmd->se_deve)
                        goto after_mode_sense;

                if (task->task_se_cmd->se_deve->lun_flags &
                                TRANSPORT_LUNFLAGS_READ_ONLY) {
                        unsigned char *buf = transport_kmap_data_sg(task->task_se_cmd);

                        if (cdb[0] == MODE_SENSE_10) {
                                if (!(buf[3] & 0x80))
                                        buf[3] |= 0x80;
                        } else {
                                if (!(buf[2] & 0x80))
                                        buf[2] |= 0x80;
                        }

                        transport_kunmap_data_sg(task->task_se_cmd);
                }
        }
after_mode_sense:

        if (sd->type != TYPE_TAPE)
                goto after_mode_select;

        /*
         * Hack to correctly obtain the initiator requested blocksize for
         * TYPE_TAPE.  Since this value is dependent upon each tape media,
         * struct scsi_device->sector_size will not contain the correct value
         * by default, so we go ahead and set it so
         * TRANSPORT(dev)->get_blockdev() returns the correct value to the
         * storage engine.
         */
        if (((cdb[0] == MODE_SELECT) || (cdb[0] == MODE_SELECT_10)) &&
              (status_byte(result) << 1) == SAM_STAT_GOOD) {
                unsigned char *buf;
                struct scatterlist *sg = task->task_sg;
                u16 bdl;
                u32 blocksize;

                buf = sg_virt(&sg[0]);
                if (!buf) {
                        pr_err("Unable to get buf for scatterlist\n");
                        goto after_mode_select;
                }

                if (cdb[0] == MODE_SELECT)
                        bdl = (buf[3]);
                else
                        bdl = (buf[6] << 8) | (buf[7]);

                if (!bdl)
                        goto after_mode_select;

                if (cdb[0] == MODE_SELECT)
                        blocksize = (buf[9] << 16) | (buf[10] << 8) |
                                        (buf[11]);
                else
                        blocksize = (buf[13] << 16) | (buf[14] << 8) |
                                        (buf[15]);

                sd->sector_size = blocksize;
        }
after_mode_select:

        if (status_byte(result) & CHECK_CONDITION)
                return 1;

        return 0;
}

static struct se_task *
pscsi_alloc_task(unsigned char *cdb)
{
        struct pscsi_plugin_task *pt;

        /*
         * Dynamically alloc cdb space, since it may be larger than
         * TCM_MAX_COMMAND_SIZE
         */
        pt = kzalloc(sizeof(*pt) + scsi_command_size(cdb), GFP_KERNEL);
        if (!pt) {
                pr_err("Unable to allocate struct pscsi_plugin_task\n");
                return NULL;
        }

        return &pt->pscsi_task;
}

static void pscsi_free_task(struct se_task *task)
{
        struct pscsi_plugin_task *pt = PSCSI_TASK(task);

        /*
         * We do not release the bio(s) here associated with this task, as
         * this is handled by bio_put() and pscsi_bi_endio().
         */
        kfree(pt);
}

enum {
        Opt_scsi_host_id, Opt_scsi_channel_id, Opt_scsi_target_id,
        Opt_scsi_lun_id, Opt_err
};

static match_table_t tokens = {
        {Opt_scsi_host_id, "scsi_host_id=%d"},
        {Opt_scsi_channel_id, "scsi_channel_id=%d"},
        {Opt_scsi_target_id, "scsi_target_id=%d"},
        {Opt_scsi_lun_id, "scsi_lun_id=%d"},
        {Opt_err, NULL}
};

static ssize_t pscsi_set_configfs_dev_params(struct se_hba *hba,
        struct se_subsystem_dev *se_dev,
        const char *page,
        ssize_t count)
{
        struct pscsi_dev_virt *pdv = se_dev->se_dev_su_ptr;
        struct pscsi_hba_virt *phv = hba->hba_ptr;
        char *orig, *ptr, *opts;
        substring_t args[MAX_OPT_ARGS];
        int ret = 0, arg, token;

        opts = kstrdup(page, GFP_KERNEL);
        if (!opts)
                return -ENOMEM;

        orig = opts;

        while ((ptr = strsep(&opts, ",")) != NULL) {
                if (!*ptr)
                        continue;

                token = match_token(ptr, tokens, args);
                switch (token) {
                case Opt_scsi_host_id:
                        if (phv->phv_mode == PHV_LLD_SCSI_HOST_NO) {
                                pr_err("PSCSI[%d]: Unable to accept"
                                        " scsi_host_id while phv_mode =="
                                        " PHV_LLD_SCSI_HOST_NO\n",
                                        phv->phv_host_id);
                                ret = -EINVAL;
                                goto out;
                        }
                        match_int(args, &arg);
                        pdv->pdv_host_id = arg;
                        pr_debug("PSCSI[%d]: Referencing SCSI Host ID:"
                                " %d\n", phv->phv_host_id, pdv->pdv_host_id);
                        pdv->pdv_flags |= PDF_HAS_VIRT_HOST_ID;
                        break;
                case Opt_scsi_channel_id:
                        match_int(args, &arg);
                        pdv->pdv_channel_id = arg;
                        pr_debug("PSCSI[%d]: Referencing SCSI Channel"
                                " ID: %d\n",  phv->phv_host_id,
                                pdv->pdv_channel_id);
                        pdv->pdv_flags |= PDF_HAS_CHANNEL_ID;
                        break;
                case Opt_scsi_target_id:
                        match_int(args, &arg);
                        pdv->pdv_target_id = arg;
                        pr_debug("PSCSI[%d]: Referencing SCSI Target"
                                " ID: %d\n", phv->phv_host_id,
                                pdv->pdv_target_id);
                        pdv->pdv_flags |= PDF_HAS_TARGET_ID;
                        break;
                case Opt_scsi_lun_id:
                        match_int(args, &arg);
                        pdv->pdv_lun_id = arg;
                        pr_debug("PSCSI[%d]: Referencing SCSI LUN ID:"
                                " %d\n", phv->phv_host_id, pdv->pdv_lun_id);
                        pdv->pdv_flags |= PDF_HAS_LUN_ID;
                        break;
                default:
                        break;
                }
        }

out:
        kfree(orig);
        return (!ret) ? count : ret;
}

static ssize_t pscsi_check_configfs_dev_params(
        struct se_hba *hba,
        struct se_subsystem_dev *se_dev)
{
        struct pscsi_dev_virt *pdv = se_dev->se_dev_su_ptr;

        if (!(pdv->pdv_flags & PDF_HAS_CHANNEL_ID) ||
            !(pdv->pdv_flags & PDF_HAS_TARGET_ID) ||
            !(pdv->pdv_flags & PDF_HAS_LUN_ID)) {
                pr_err("Missing scsi_channel_id=, scsi_target_id= and"
                        " scsi_lun_id= parameters\n");
                return -EINVAL;
        }

        return 0;
}

static ssize_t pscsi_show_configfs_dev_params(struct se_hba *hba,
                                              struct se_subsystem_dev *se_dev,
                                              char *b)
{
        struct pscsi_hba_virt *phv = hba->hba_ptr;
        struct pscsi_dev_virt *pdv = se_dev->se_dev_su_ptr;
        struct scsi_device *sd = pdv->pdv_sd;
        unsigned char host_id[16];
        ssize_t bl;
        int i;

        if (phv->phv_mode == PHV_VIRUTAL_HOST_ID)
                snprintf(host_id, 16, "%d", pdv->pdv_host_id);
        else
                snprintf(host_id, 16, "PHBA Mode");

        bl = sprintf(b, "SCSI Device Bus Location:"
                " Channel ID: %d Target ID: %d LUN: %d Host ID: %s\n",
                pdv->pdv_channel_id, pdv->pdv_target_id, pdv->pdv_lun_id,
                host_id);

        if (sd) {
                bl += sprintf(b + bl, "        ");
                bl += sprintf(b + bl, "Vendor: ");
                for (i = 0; i < 8; i++) {
                        if (ISPRINT(sd->vendor[i]))   /* printable character? */
                                bl += sprintf(b + bl, "%c", sd->vendor[i]);
                        else
                                bl += sprintf(b + bl, " ");
                }
                bl += sprintf(b + bl, " Model: ");
                for (i = 0; i < 16; i++) {
                        if (ISPRINT(sd->model[i]))   /* printable character ? */
                                bl += sprintf(b + bl, "%c", sd->model[i]);
                        else
                                bl += sprintf(b + bl, " ");
                }
                bl += sprintf(b + bl, " Rev: ");
                for (i = 0; i < 4; i++) {
                        if (ISPRINT(sd->rev[i]))   /* printable character ? */
                                bl += sprintf(b + bl, "%c", sd->rev[i]);
                        else
                                bl += sprintf(b + bl, " ");
                }
                bl += sprintf(b + bl, "\n");
        }
        return bl;
}

static void pscsi_bi_endio(struct bio *bio, int error)
{
        bio_put(bio);
}

static inline struct bio *pscsi_get_bio(int sg_num)
{
        struct bio *bio;
        /*
         * Use bio_malloc() following the comment in for bio -> struct request
         * in block/blk-core.c:blk_make_request()
         */
        bio = bio_kmalloc(GFP_KERNEL, sg_num);
        if (!bio) {
                pr_err("PSCSI: bio_kmalloc() failed\n");
                return NULL;
        }
        bio->bi_end_io = pscsi_bi_endio;

        return bio;
}

static int pscsi_map_sg(struct se_task *task, struct scatterlist *task_sg,
                struct bio **hbio)
{
        struct se_cmd *cmd = task->task_se_cmd;
        struct pscsi_dev_virt *pdv = task->task_se_cmd->se_dev->dev_ptr;
        u32 task_sg_num = task->task_sg_nents;
        struct bio *bio = NULL, *tbio = NULL;
        struct page *page;
        struct scatterlist *sg;
        u32 data_len = task->task_size, i, len, bytes, off;
        int nr_pages = (task->task_size + task_sg[0].offset +
                        PAGE_SIZE - 1) >> PAGE_SHIFT;
        int nr_vecs = 0, rc;
        int rw = (task->task_data_direction == DMA_TO_DEVICE);

        *hbio = NULL;

        pr_debug("PSCSI: nr_pages: %d\n", nr_pages);

        for_each_sg(task_sg, sg, task_sg_num, i) {
                page = sg_page(sg);
                off = sg->offset;
                len = sg->length;

                pr_debug("PSCSI: i: %d page: %p len: %d off: %d\n", i,
                        page, len, off);

                while (len > 0 && data_len > 0) {
                        bytes = min_t(unsigned int, len, PAGE_SIZE - off);
                        bytes = min(bytes, data_len);

                        if (!bio) {
                                nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
                                nr_pages -= nr_vecs;
                                /*

                                 * Calls bio_kmalloc() and sets bio->bi_end_io()
                                 */
                                bio = pscsi_get_bio(nr_vecs);
                                if (!bio)
                                        goto fail;

                                if (rw)
                                        bio->bi_rw |= REQ_WRITE;

                                pr_debug("PSCSI: Allocated bio: %p,"
                                        " dir: %s nr_vecs: %d\n", bio,
                                        (rw) ? "rw" : "r", nr_vecs);
                                /*
                                 * Set *hbio pointer to handle the case:
                                 * nr_pages > BIO_MAX_PAGES, where additional
                                 * bios need to be added to complete a given
                                 * struct se_task
                                 */
                                if (!*hbio)
                                        *hbio = tbio = bio;
                                else
                                        tbio = tbio->bi_next = bio;
                        }

                        pr_debug("PSCSI: Calling bio_add_pc_page() i: %d"
                                " bio: %p page: %p len: %d off: %d\n", i, bio,
                                page, len, off);

                        rc = bio_add_pc_page(pdv->pdv_sd->request_queue,
                                        bio, page, bytes, off);
                        if (rc != bytes)
                                goto fail;

                        pr_debug("PSCSI: bio->bi_vcnt: %d nr_vecs: %d\n",
                                bio->bi_vcnt, nr_vecs);

                        if (bio->bi_vcnt > nr_vecs) {
                                pr_debug("PSCSI: Reached bio->bi_vcnt max:"
                                        " %d i: %d bio: %p, allocating another"
                                        " bio\n", bio->bi_vcnt, i, bio);
                                /*
                                 * Clear the pointer so that another bio will
                                 * be allocated with pscsi_get_bio() above, the
                                 * current bio has already been set *tbio and
                                 * bio->bi_next.
                                 */
                                bio = NULL;
                        }

                        page++;
                        len -= bytes;
                        data_len -= bytes;
                        off = 0;
                }
        }

        return task->task_sg_nents;
fail:
        while (*hbio) {
                bio = *hbio;
                *hbio = (*hbio)->bi_next;
                bio->bi_next = NULL;
                bio_endio(bio, 0);      /* XXX: should be error */
        }
        cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
        return -ENOMEM;
}

static int pscsi_do_task(struct se_task *task)
{
        struct se_cmd *cmd = task->task_se_cmd;
        struct pscsi_dev_virt *pdv = task->task_se_cmd->se_dev->dev_ptr;
        struct pscsi_plugin_task *pt = PSCSI_TASK(task);
        struct request *req;
        struct bio *hbio;
        int ret;

        target_get_task_cdb(task, pt->pscsi_cdb);

        if (task->task_se_cmd->se_cmd_flags & SCF_SCSI_NON_DATA_CDB) {
                req = blk_get_request(pdv->pdv_sd->request_queue,
                                (task->task_data_direction == DMA_TO_DEVICE),
                                GFP_KERNEL);
                if (!req || IS_ERR(req)) {
                        pr_err("PSCSI: blk_get_request() failed: %ld\n",
                                        req ? IS_ERR(req) : -ENOMEM);
                        cmd->scsi_sense_reason =
                                TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                        return -ENODEV;
                }
        } else {
                BUG_ON(!task->task_size);

                /*
                 * Setup the main struct request for the task->task_sg[] payload
                 */
                ret = pscsi_map_sg(task, task->task_sg, &hbio);
                if (ret < 0) {
                        cmd->scsi_sense_reason =
                                TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                        return ret;
                }

                req = blk_make_request(pdv->pdv_sd->request_queue, hbio,
                                       GFP_KERNEL);
                if (IS_ERR(req)) {
                        pr_err("pSCSI: blk_make_request() failed\n");
                        goto fail;
                }
        }

        req->cmd_type = REQ_TYPE_BLOCK_PC;
        req->end_io = pscsi_req_done;
        req->end_io_data = task;
        req->cmd_len = scsi_command_size(pt->pscsi_cdb);
        req->cmd = &pt->pscsi_cdb[0];
        req->sense = &pt->pscsi_sense[0];
        req->sense_len = 0;
        if (pdv->pdv_sd->type == TYPE_DISK)
                req->timeout = PS_TIMEOUT_DISK;
        else
                req->timeout = PS_TIMEOUT_OTHER;
        req->retries = PS_RETRY;

        blk_execute_rq_nowait(pdv->pdv_sd->request_queue, NULL, req,
                        (task->task_se_cmd->sam_task_attr == MSG_HEAD_TAG),
                        pscsi_req_done);

        return 0;

fail:
        while (hbio) {
                struct bio *bio = hbio;
                hbio = hbio->bi_next;
                bio->bi_next = NULL;
                bio_endio(bio, 0);      /* XXX: should be error */
        }
        cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
        return -ENOMEM;
}

/*      pscsi_get_sense_buffer():
 *
 *
 */
static unsigned char *pscsi_get_sense_buffer(struct se_task *task)
{
        struct pscsi_plugin_task *pt = PSCSI_TASK(task);

        return (unsigned char *)&pt->pscsi_sense[0];
}

/*      pscsi_get_device_rev():
 *
 *
 */
static u32 pscsi_get_device_rev(struct se_device *dev)
{
        struct pscsi_dev_virt *pdv = dev->dev_ptr;
        struct scsi_device *sd = pdv->pdv_sd;

        return (sd->scsi_level - 1) ? sd->scsi_level - 1 : 1;
}

/*      pscsi_get_device_type():
 *
 *
 */
static u32 pscsi_get_device_type(struct se_device *dev)
{
        struct pscsi_dev_virt *pdv = dev->dev_ptr;
        struct scsi_device *sd = pdv->pdv_sd;

        return (sd) ? sd->type : TYPE_NO_LUN;
}

static sector_t pscsi_get_blocks(struct se_device *dev)
{
        struct pscsi_dev_virt *pdv = dev->dev_ptr;

        if (pdv->pdv_bd && pdv->pdv_bd->bd_part)
                return pdv->pdv_bd->bd_part->nr_sects;

        dump_stack();
        return 0;
}

/*      pscsi_handle_SAM_STATUS_failures():
 *
 *
 */
static inline void pscsi_process_SAM_status(
        struct se_task *task,
        struct pscsi_plugin_task *pt)
{
        task->task_scsi_status = status_byte(pt->pscsi_result);
        if (task->task_scsi_status) {
                task->task_scsi_status <<= 1;
                pr_debug("PSCSI Status Byte exception at task: %p CDB:"
                        " 0x%02x Result: 0x%08x\n", task, pt->pscsi_cdb[0],
                        pt->pscsi_result);
        }

        switch (host_byte(pt->pscsi_result)) {
        case DID_OK:
                transport_complete_task(task, (!task->task_scsi_status));
                break;
        default:
                pr_debug("PSCSI Host Byte exception at task: %p CDB:"
                        " 0x%02x Result: 0x%08x\n", task, pt->pscsi_cdb[0],
                        pt->pscsi_result);
                task->task_scsi_status = SAM_STAT_CHECK_CONDITION;
                task->task_se_cmd->scsi_sense_reason =
                                        TCM_UNSUPPORTED_SCSI_OPCODE;
                transport_complete_task(task, 0);
                break;
        }
}

static void pscsi_req_done(struct request *req, int uptodate)
{
        struct se_task *task = req->end_io_data;
        struct pscsi_plugin_task *pt = PSCSI_TASK(task);

        pt->pscsi_result = req->errors;
        pt->pscsi_resid = req->resid_len;

        pscsi_process_SAM_status(task, pt);
        __blk_put_request(req->q, req);
}

static struct se_subsystem_api pscsi_template = {
        .name                   = "pscsi",
        .owner                  = THIS_MODULE,
        .transport_type         = TRANSPORT_PLUGIN_PHBA_PDEV,
        .attach_hba             = pscsi_attach_hba,
        .detach_hba             = pscsi_detach_hba,
        .pmode_enable_hba       = pscsi_pmode_enable_hba,
        .allocate_virtdevice    = pscsi_allocate_virtdevice,
        .create_virtdevice      = pscsi_create_virtdevice,
        .free_device            = pscsi_free_device,
        .transport_complete     = pscsi_transport_complete,
        .alloc_task             = pscsi_alloc_task,
        .do_task                = pscsi_do_task,
        .free_task              = pscsi_free_task,
        .check_configfs_dev_params = pscsi_check_configfs_dev_params,
        .set_configfs_dev_params = pscsi_set_configfs_dev_params,
        .show_configfs_dev_params = pscsi_show_configfs_dev_params,
        .get_sense_buffer       = pscsi_get_sense_buffer,
        .get_device_rev         = pscsi_get_device_rev,
        .get_device_type        = pscsi_get_device_type,
        .get_blocks             = pscsi_get_blocks,
};

static int __init pscsi_module_init(void)
{
        return transport_subsystem_register(&pscsi_template);
}

static void pscsi_module_exit(void)
{
        transport_subsystem_release(&pscsi_template);
}

MODULE_DESCRIPTION("TCM PSCSI subsystem plugin");
MODULE_AUTHOR("nab@Linux-iSCSI.org");
MODULE_LICENSE("GPL");

module_init(pscsi_module_init);
module_exit(pscsi_module_exit);