/*******************************************************************************
   * 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
  ");

  		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
  ", hba->hba_id,
  		PSCSI_VERSION, TARGET_CORE_MOD_VERSION);

  	pr_debug("CORE_HBA[%d] - Attached SCSI HBA to Generic
  ",

  	       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
  ", 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
  ", 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
  ", 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 (IS_ERR(sh)) {

  		pr_err("pSCSI: Unable to locate SCSI Host for"

  			" phv_host_id: %d
  ", phv->phv_host_id);

  		return PTR_ERR(sh);

  	}

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

  	pr_debug("CORE_HBA[%d] - Enabled pSCSI HBA Passthrough %s
  ",

  		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!
  ");
  			break;
  		}

  		pr_debug("T10 VPD Identifer Length: %d
  ", ident_len);

  
  		vpd = kzalloc(sizeof(struct t10_vpd), GFP_KERNEL);
  		if (!vpd) {

  			pr_err("Unable to allocate memory for"

  					" struct t10_vpd
  ");
  			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
  ", 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
  ");

  		return NULL;
  	}
  	pdv->pdv_se_hba = hba;

  	pr_debug("PSCSI: Allocated pdv: %p for %s
  ", 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
  ",

  			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
  ");

  		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
  ",

  		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
  ",

  			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
  ",

  		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
  ",

  		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
  ");

  		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
  ");

  			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
  ");

  			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
  ");
  				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 (IS_ERR(sh)) {

  				pr_err("pSCSI: Unable to locate"

  					" pdv_host_id: %d
  ", pdv->pdv_host_id);

  				return ERR_CAST(sh);

  			}
  		}
  	} else {
  		if (phv->phv_mode == PHV_VIRUTAL_HOST_ID) {

  			pr_err("pSCSI: PHV_VIRUTAL_HOST_ID set while"

  				" struct Scsi_Host exists
  ");

  			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
  ", 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);
  
  		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_first_data_page(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_first_data_page(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
  ");

  			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
  ");

  		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
  ",
  					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
  ", 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
  ",  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
  ", 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
  ", 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
  ");

  		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
  ",
  		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, "
  ");
  	}
  	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
  ");

  		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
  ", 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
  ", 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
  ", 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
  ", 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
  ",

  				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
  ", 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
  ",
  					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
  ");
  			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->type;
  }
  
  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
  ", 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
  ", 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);