/*******************************************************************************
   * Filename:  target_core_pr.c
   *
   * This file contains SPC-3 compliant persistent reservations and
   * legacy SPC-2 reservations with compatible reservation handling (CRH=1)
   *
   * Copyright (c) 2009, 2010 Rising Tide Systems
   * Copyright (c) 2009, 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/slab.h>
  #include <linux/spinlock.h>
  #include <linux/list.h>
  #include <scsi/scsi.h>
  #include <scsi/scsi_cmnd.h>
  #include <asm/unaligned.h>
  
  #include <target/target_core_base.h>
  #include <target/target_core_device.h>
  #include <target/target_core_tmr.h>
  #include <target/target_core_tpg.h>
  #include <target/target_core_transport.h>
  #include <target/target_core_fabric_ops.h>
  #include <target/target_core_configfs.h>
  
  #include "target_core_hba.h"
  #include "target_core_pr.h"
  #include "target_core_ua.h"
  
  /*
   * Used for Specify Initiator Ports Capable Bit (SPEC_I_PT)
   */
  struct pr_transport_id_holder {
  	int dest_local_nexus;
  	struct t10_pr_registration *dest_pr_reg;
  	struct se_portal_group *dest_tpg;
  	struct se_node_acl *dest_node_acl;
  	struct se_dev_entry *dest_se_deve;
  	struct list_head dest_list;
  };
  
  int core_pr_dump_initiator_port(
  	struct t10_pr_registration *pr_reg,
  	char *buf,
  	u32 size)
  {

  	if (!pr_reg->isid_present_at_reg)

  		return 0;
  
  	snprintf(buf, size, ",i,0x%s", &pr_reg->pr_reg_isid[0]);
  	return 1;
  }
  
  static void __core_scsi3_complete_pro_release(struct se_device *, struct se_node_acl *,
  			struct t10_pr_registration *, int);
  
  static int core_scsi2_reservation_seq_non_holder(
  	struct se_cmd *cmd,
  	unsigned char *cdb,
  	u32 pr_reg_type)
  {
  	switch (cdb[0]) {
  	case INQUIRY:
  	case RELEASE:
  	case RELEASE_10:
  		return 0;
  	default:
  		return 1;
  	}
  
  	return 1;
  }
  
  static int core_scsi2_reservation_check(struct se_cmd *cmd, u32 *pr_reg_type)
  {
  	struct se_device *dev = cmd->se_dev;
  	struct se_session *sess = cmd->se_sess;
  	int ret;

  	if (!sess)

  		return 0;
  
  	spin_lock(&dev->dev_reservation_lock);
  	if (!dev->dev_reserved_node_acl || !sess) {
  		spin_unlock(&dev->dev_reservation_lock);
  		return 0;
  	}
  	if (dev->dev_reserved_node_acl != sess->se_node_acl) {
  		spin_unlock(&dev->dev_reservation_lock);

  		return -EINVAL;

  	}
  	if (!(dev->dev_flags & DF_SPC2_RESERVATIONS_WITH_ISID)) {
  		spin_unlock(&dev->dev_reservation_lock);
  		return 0;
  	}

  	ret = (dev->dev_res_bin_isid == sess->sess_bin_isid) ? 0 : -EINVAL;

  	spin_unlock(&dev->dev_reservation_lock);
  
  	return ret;
  }

  static struct t10_pr_registration *core_scsi3_locate_pr_reg(struct se_device *,
  					struct se_node_acl *, struct se_session *);
  static void core_scsi3_put_pr_reg(struct t10_pr_registration *);
  
  static int target_check_scsi2_reservation_conflict(struct se_cmd *cmd, int *ret)
  {
  	struct se_session *se_sess = cmd->se_sess;
  	struct se_subsystem_dev *su_dev = cmd->se_dev->se_sub_dev;
  	struct t10_pr_registration *pr_reg;
  	struct t10_reservation *pr_tmpl = &su_dev->t10_pr;
  	int crh = (su_dev->t10_pr.res_type == SPC3_PERSISTENT_RESERVATIONS);
  	int conflict = 0;
  
  	if (!crh)
  		return false;
  
  	pr_reg = core_scsi3_locate_pr_reg(cmd->se_dev, se_sess->se_node_acl,
  			se_sess);
  	if (pr_reg) {
  		/*
  		 * From spc4r17 5.7.3 Exceptions to SPC-2 RESERVE and RELEASE
  		 * behavior
  		 *
  		 * A RESERVE(6) or RESERVE(10) command shall complete with GOOD
  		 * status, but no reservation shall be established and the
  		 * persistent reservation shall not be changed, if the command
  		 * is received from a) and b) below.
  		 *
  		 * A RELEASE(6) or RELEASE(10) command shall complete with GOOD
  		 * status, but the persistent reservation shall not be released,
  		 * if the command is received from a) and b)
  		 *
  		 * a) An I_T nexus that is a persistent reservation holder; or
  		 * b) An I_T nexus that is registered if a registrants only or
  		 *    all registrants type persistent reservation is present.
  		 *
  		 * In all other cases, a RESERVE(6) command, RESERVE(10) command,
  		 * RELEASE(6) command, or RELEASE(10) command shall be processed
  		 * as defined in SPC-2.
  		 */
  		if (pr_reg->pr_res_holder) {
  			core_scsi3_put_pr_reg(pr_reg);
  			*ret = 0;
  			return false;
  		}
  		if ((pr_reg->pr_res_type == PR_TYPE_WRITE_EXCLUSIVE_REGONLY) ||
  		    (pr_reg->pr_res_type == PR_TYPE_EXCLUSIVE_ACCESS_REGONLY) ||
  		    (pr_reg->pr_res_type == PR_TYPE_WRITE_EXCLUSIVE_ALLREG) ||
  		    (pr_reg->pr_res_type == PR_TYPE_EXCLUSIVE_ACCESS_ALLREG)) {
  			core_scsi3_put_pr_reg(pr_reg);
  			*ret = 0;
  			return true;
  		}
  		core_scsi3_put_pr_reg(pr_reg);
  		conflict = 1;
  	} else {
  		/*
  		 * Following spc2r20 5.5.1 Reservations overview:
  		 *
  		 * If a logical unit has executed a PERSISTENT RESERVE OUT
  		 * command with the REGISTER or the REGISTER AND IGNORE
  		 * EXISTING KEY service action and is still registered by any
  		 * initiator, all RESERVE commands and all RELEASE commands
  		 * regardless of initiator shall conflict and shall terminate
  		 * with a RESERVATION CONFLICT status.
  		 */
  		spin_lock(&pr_tmpl->registration_lock);
  		conflict = (list_empty(&pr_tmpl->registration_list)) ? 0 : 1;
  		spin_unlock(&pr_tmpl->registration_lock);
  	}
  
  	if (conflict) {
  		pr_err("Received legacy SPC-2 RESERVE/RELEASE"
  			" while active SPC-3 registrations exist,"
  			" returning RESERVATION_CONFLICT
  ");

  		cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;

  		return true;
  	}
  
  	return false;
  }

  int target_scsi2_reservation_release(struct se_task *task)

  {

  	struct se_cmd *cmd = task->task_se_cmd;

  	struct se_device *dev = cmd->se_dev;
  	struct se_session *sess = cmd->se_sess;
  	struct se_portal_group *tpg = sess->se_tpg;

  	int ret = 0;

  	if (!sess || !tpg)

  		goto out;

  	if (target_check_scsi2_reservation_conflict(cmd, &ret))

  		goto out;

  	ret = 0;

  	spin_lock(&dev->dev_reservation_lock);

  	if (!dev->dev_reserved_node_acl || !sess)
  		goto out_unlock;
  
  	if (dev->dev_reserved_node_acl != sess->se_node_acl)
  		goto out_unlock;

  	dev->dev_reserved_node_acl = NULL;
  	dev->dev_flags &= ~DF_SPC2_RESERVATIONS;
  	if (dev->dev_flags & DF_SPC2_RESERVATIONS_WITH_ISID) {
  		dev->dev_res_bin_isid = 0;
  		dev->dev_flags &= ~DF_SPC2_RESERVATIONS_WITH_ISID;
  	}

  	pr_debug("SCSI-2 Released reservation for %s LUN: %u ->"

  		" MAPPED LUN: %u for %s
  ", tpg->se_tpg_tfo->get_fabric_name(),
  		cmd->se_lun->unpacked_lun, cmd->se_deve->mapped_lun,

  		sess->se_node_acl->initiatorname);

  out_unlock:
  	spin_unlock(&dev->dev_reservation_lock);
  out:
  	if (!ret) {
  		task->task_scsi_status = GOOD;
  		transport_complete_task(task, 1);
  	}
  	return ret;

  }

  int target_scsi2_reservation_reserve(struct se_task *task)

  {

  	struct se_cmd *cmd = task->task_se_cmd;

  	struct se_device *dev = cmd->se_dev;
  	struct se_session *sess = cmd->se_sess;
  	struct se_portal_group *tpg = sess->se_tpg;

  	int ret = 0;

  	if ((cmd->t_task_cdb[1] & 0x01) &&
  	    (cmd->t_task_cdb[1] & 0x02)) {

  		pr_err("LongIO and Obselete Bits set, returning"

  				" ILLEGAL_REQUEST
  ");

  		cmd->scsi_sense_reason = TCM_UNSUPPORTED_SCSI_OPCODE;
  		ret = -EINVAL;

  		goto out;

  	}
  	/*
  	 * This is currently the case for target_core_mod passthrough struct se_cmd
  	 * ops
  	 */

  	if (!sess || !tpg)

  		goto out;

  	if (target_check_scsi2_reservation_conflict(cmd, &ret))

  		goto out;

  	ret = 0;

  	spin_lock(&dev->dev_reservation_lock);
  	if (dev->dev_reserved_node_acl &&
  	   (dev->dev_reserved_node_acl != sess->se_node_acl)) {

  		pr_err("SCSI-2 RESERVATION CONFLIFT for %s fabric
  ",

  			tpg->se_tpg_tfo->get_fabric_name());

  		pr_err("Original reserver LUN: %u %s
  ",

  			cmd->se_lun->unpacked_lun,

  			dev->dev_reserved_node_acl->initiatorname);

  		pr_err("Current attempt - LUN: %u -> MAPPED LUN: %u"

  			" from %s 
  ", cmd->se_lun->unpacked_lun,

  			cmd->se_deve->mapped_lun,
  			sess->se_node_acl->initiatorname);

  		cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  		ret = -EINVAL;

  		goto out_unlock;

  	}
  
  	dev->dev_reserved_node_acl = sess->se_node_acl;
  	dev->dev_flags |= DF_SPC2_RESERVATIONS;
  	if (sess->sess_bin_isid != 0) {
  		dev->dev_res_bin_isid = sess->sess_bin_isid;
  		dev->dev_flags |= DF_SPC2_RESERVATIONS_WITH_ISID;
  	}

  	pr_debug("SCSI-2 Reserved %s LUN: %u -> MAPPED LUN: %u"

  		" for %s
  ", tpg->se_tpg_tfo->get_fabric_name(),
  		cmd->se_lun->unpacked_lun, cmd->se_deve->mapped_lun,

  		sess->se_node_acl->initiatorname);

  out_unlock:
  	spin_unlock(&dev->dev_reservation_lock);
  out:
  	if (!ret) {
  		task->task_scsi_status = GOOD;
  		transport_complete_task(task, 1);
  	}
  	return ret;

  }

  
  /*
   * Begin SPC-3/SPC-4 Persistent Reservations emulation support
   *
   * This function is called by those initiator ports who are *NOT*
   * the active PR reservation holder when a reservation is present.
   */
  static int core_scsi3_pr_seq_non_holder(
  	struct se_cmd *cmd,
  	unsigned char *cdb,
  	u32 pr_reg_type)
  {
  	struct se_dev_entry *se_deve;

  	struct se_session *se_sess = cmd->se_sess;

  	int other_cdb = 0, ignore_reg;
  	int registered_nexus = 0, ret = 1; /* Conflict by default */
  	int all_reg = 0, reg_only = 0; /* ALL_REG, REG_ONLY */
  	int we = 0; /* Write Exclusive */
  	int legacy = 0; /* Act like a legacy device and return
  			 * RESERVATION CONFLICT on some CDBs */
  	/*
  	 * A legacy SPC-2 reservation is being held.
  	 */
  	if (cmd->se_dev->dev_flags & DF_SPC2_RESERVATIONS)
  		return core_scsi2_reservation_seq_non_holder(cmd,
  					cdb, pr_reg_type);
  
  	se_deve = &se_sess->se_node_acl->device_list[cmd->orig_fe_lun];
  	/*
  	 * Determine if the registration should be ignored due to
  	 * non-matching ISIDs in core_scsi3_pr_reservation_check().
  	 */
  	ignore_reg = (pr_reg_type & 0x80000000);
  	if (ignore_reg)
  		pr_reg_type &= ~0x80000000;
  
  	switch (pr_reg_type) {
  	case PR_TYPE_WRITE_EXCLUSIVE:
  		we = 1;
  	case PR_TYPE_EXCLUSIVE_ACCESS:
  		/*
  		 * Some commands are only allowed for the persistent reservation
  		 * holder.
  		 */
  		if ((se_deve->def_pr_registered) && !(ignore_reg))
  			registered_nexus = 1;
  		break;
  	case PR_TYPE_WRITE_EXCLUSIVE_REGONLY:
  		we = 1;
  	case PR_TYPE_EXCLUSIVE_ACCESS_REGONLY:
  		/*
  		 * Some commands are only allowed for registered I_T Nexuses.
  		 */
  		reg_only = 1;
  		if ((se_deve->def_pr_registered) && !(ignore_reg))
  			registered_nexus = 1;
  		break;
  	case PR_TYPE_WRITE_EXCLUSIVE_ALLREG:
  		we = 1;
  	case PR_TYPE_EXCLUSIVE_ACCESS_ALLREG:
  		/*
  		 * Each registered I_T Nexus is a reservation holder.
  		 */
  		all_reg = 1;
  		if ((se_deve->def_pr_registered) && !(ignore_reg))
  			registered_nexus = 1;
  		break;
  	default:

  		return -EINVAL;

  	}
  	/*
  	 * Referenced from spc4r17 table 45 for *NON* PR holder access
  	 */
  	switch (cdb[0]) {
  	case SECURITY_PROTOCOL_IN:
  		if (registered_nexus)
  			return 0;
  		ret = (we) ? 0 : 1;
  		break;
  	case MODE_SENSE:
  	case MODE_SENSE_10:
  	case READ_ATTRIBUTE:
  	case READ_BUFFER:
  	case RECEIVE_DIAGNOSTIC:
  		if (legacy) {
  			ret = 1;
  			break;
  		}
  		if (registered_nexus) {
  			ret = 0;
  			break;
  		}
  		ret = (we) ? 0 : 1; /* Allowed Write Exclusive */
  		break;
  	case PERSISTENT_RESERVE_OUT:
  		/*
  		 * This follows PERSISTENT_RESERVE_OUT service actions that
  		 * are allowed in the presence of various reservations.
  		 * See spc4r17, table 46
  		 */
  		switch (cdb[1] & 0x1f) {
  		case PRO_CLEAR:
  		case PRO_PREEMPT:
  		case PRO_PREEMPT_AND_ABORT:
  			ret = (registered_nexus) ? 0 : 1;
  			break;
  		case PRO_REGISTER:
  		case PRO_REGISTER_AND_IGNORE_EXISTING_KEY:
  			ret = 0;
  			break;
  		case PRO_REGISTER_AND_MOVE:
  		case PRO_RESERVE:
  			ret = 1;
  			break;
  		case PRO_RELEASE:
  			ret = (registered_nexus) ? 0 : 1;
  			break;
  		default:

  			pr_err("Unknown PERSISTENT_RESERVE_OUT service"

  				" action: 0x%02x
  ", cdb[1] & 0x1f);

  			return -EINVAL;

  		}
  		break;
  	case RELEASE:
  	case RELEASE_10:

  		/* Handled by CRH=1 in target_scsi2_reservation_release() */

  		ret = 0;
  		break;
  	case RESERVE:
  	case RESERVE_10:

  		/* Handled by CRH=1 in target_scsi2_reservation_reserve() */

  		ret = 0;
  		break;
  	case TEST_UNIT_READY:
  		ret = (legacy) ? 1 : 0; /* Conflict for legacy */
  		break;
  	case MAINTENANCE_IN:
  		switch (cdb[1] & 0x1f) {
  		case MI_MANAGEMENT_PROTOCOL_IN:
  			if (registered_nexus) {
  				ret = 0;
  				break;
  			}
  			ret = (we) ? 0 : 1; /* Allowed Write Exclusive */
  			break;
  		case MI_REPORT_SUPPORTED_OPERATION_CODES:
  		case MI_REPORT_SUPPORTED_TASK_MANAGEMENT_FUNCTIONS:
  			if (legacy) {
  				ret = 1;
  				break;
  			}
  			if (registered_nexus) {
  				ret = 0;
  				break;
  			}
  			ret = (we) ? 0 : 1; /* Allowed Write Exclusive */
  			break;
  		case MI_REPORT_ALIASES:
  		case MI_REPORT_IDENTIFYING_INFORMATION:
  		case MI_REPORT_PRIORITY:
  		case MI_REPORT_TARGET_PGS:
  		case MI_REPORT_TIMESTAMP:
  			ret = 0; /* Allowed */
  			break;
  		default:

  			pr_err("Unknown MI Service Action: 0x%02x
  ",

  				(cdb[1] & 0x1f));

  			return -EINVAL;

  		}
  		break;
  	case ACCESS_CONTROL_IN:
  	case ACCESS_CONTROL_OUT:
  	case INQUIRY:
  	case LOG_SENSE:
  	case READ_MEDIA_SERIAL_NUMBER:
  	case REPORT_LUNS:
  	case REQUEST_SENSE:
  		ret = 0; /*/ Allowed CDBs */
  		break;
  	default:
  		other_cdb = 1;
  		break;
  	}
  	/*

  	 * Case where the CDB is explicitly allowed in the above switch

  	 * statement.
  	 */

  	if (!ret && !other_cdb) {

  #if 0

  		pr_debug("Allowing explict CDB: 0x%02x for %s"

  			" reservation holder
  ", cdb[0],
  			core_scsi3_pr_dump_type(pr_reg_type));
  #endif
  		return ret;
  	}
  	/*
  	 * Check if write exclusive initiator ports *NOT* holding the
  	 * WRITE_EXCLUSIVE_* reservation.
  	 */
  	if ((we) && !(registered_nexus)) {
  		if (cmd->data_direction == DMA_TO_DEVICE) {
  			/*
  			 * Conflict for write exclusive
  			 */

  			pr_debug("%s Conflict for unregistered nexus"

  				" %s CDB: 0x%02x to %s reservation
  ",
  				transport_dump_cmd_direction(cmd),
  				se_sess->se_node_acl->initiatorname, cdb[0],
  				core_scsi3_pr_dump_type(pr_reg_type));
  			return 1;
  		} else {
  			/*
  			 * Allow non WRITE CDBs for all Write Exclusive
  			 * PR TYPEs to pass for registered and
  			 * non-registered_nexuxes NOT holding the reservation.
  			 *
  			 * We only make noise for the unregisterd nexuses,
  			 * as we expect registered non-reservation holding
  			 * nexuses to issue CDBs.
  			 */
  #if 0

  			if (!registered_nexus) {
  				pr_debug("Allowing implict CDB: 0x%02x"

  					" for %s reservation on unregistered"
  					" nexus
  ", cdb[0],
  					core_scsi3_pr_dump_type(pr_reg_type));
  			}
  #endif
  			return 0;
  		}
  	} else if ((reg_only) || (all_reg)) {
  		if (registered_nexus) {
  			/*
  			 * For PR_*_REG_ONLY and PR_*_ALL_REG reservations,
  			 * allow commands from registered nexuses.
  			 */
  #if 0

  			pr_debug("Allowing implict CDB: 0x%02x for %s"

  				" reservation
  ", cdb[0],
  				core_scsi3_pr_dump_type(pr_reg_type));
  #endif
  			return 0;
  		}
  	}

  	pr_debug("%s Conflict for %sregistered nexus %s CDB: 0x%2x"

  		" for %s reservation
  ", transport_dump_cmd_direction(cmd),
  		(registered_nexus) ? "" : "un",
  		se_sess->se_node_acl->initiatorname, cdb[0],
  		core_scsi3_pr_dump_type(pr_reg_type));
  
  	return 1; /* Conflict by default */
  }
  
  static u32 core_scsi3_pr_generation(struct se_device *dev)
  {

  	struct se_subsystem_dev *su_dev = dev->se_sub_dev;

  	u32 prg;
  	/*
  	 * PRGeneration field shall contain the value of a 32-bit wrapping
  	 * counter mainted by the device server.
  	 *
  	 * Note that this is done regardless of Active Persist across
  	 * Target PowerLoss (APTPL)
  	 *
  	 * See spc4r17 section 6.3.12 READ_KEYS service action
  	 */
  	spin_lock(&dev->dev_reservation_lock);

  	prg = su_dev->t10_pr.pr_generation++;

  	spin_unlock(&dev->dev_reservation_lock);
  
  	return prg;
  }
  
  static int core_scsi3_pr_reservation_check(
  	struct se_cmd *cmd,
  	u32 *pr_reg_type)
  {
  	struct se_device *dev = cmd->se_dev;
  	struct se_session *sess = cmd->se_sess;
  	int ret;

  	if (!sess)

  		return 0;
  	/*
  	 * A legacy SPC-2 reservation is being held.
  	 */
  	if (dev->dev_flags & DF_SPC2_RESERVATIONS)
  		return core_scsi2_reservation_check(cmd, pr_reg_type);
  
  	spin_lock(&dev->dev_reservation_lock);

  	if (!dev->dev_pr_res_holder) {

  		spin_unlock(&dev->dev_reservation_lock);
  		return 0;
  	}
  	*pr_reg_type = dev->dev_pr_res_holder->pr_res_type;
  	cmd->pr_res_key = dev->dev_pr_res_holder->pr_res_key;
  	if (dev->dev_pr_res_holder->pr_reg_nacl != sess->se_node_acl) {
  		spin_unlock(&dev->dev_reservation_lock);

  		return -EINVAL;

  	}

  	if (!dev->dev_pr_res_holder->isid_present_at_reg) {

  		spin_unlock(&dev->dev_reservation_lock);
  		return 0;
  	}
  	ret = (dev->dev_pr_res_holder->pr_reg_bin_isid ==

  	       sess->sess_bin_isid) ? 0 : -EINVAL;

  	/*
  	 * Use bit in *pr_reg_type to notify ISID mismatch in
  	 * core_scsi3_pr_seq_non_holder().
  	 */
  	if (ret != 0)
  		*pr_reg_type |= 0x80000000;
  	spin_unlock(&dev->dev_reservation_lock);
  
  	return ret;
  }
  
  static struct t10_pr_registration *__core_scsi3_do_alloc_registration(
  	struct se_device *dev,
  	struct se_node_acl *nacl,
  	struct se_dev_entry *deve,
  	unsigned char *isid,
  	u64 sa_res_key,
  	int all_tg_pt,
  	int aptpl)
  {

  	struct se_subsystem_dev *su_dev = dev->se_sub_dev;

  	struct t10_pr_registration *pr_reg;
  
  	pr_reg = kmem_cache_zalloc(t10_pr_reg_cache, GFP_ATOMIC);

  	if (!pr_reg) {
  		pr_err("Unable to allocate struct t10_pr_registration
  ");

  		return NULL;
  	}

  	pr_reg->pr_aptpl_buf = kzalloc(su_dev->t10_pr.pr_aptpl_buf_len,

  					GFP_ATOMIC);

  	if (!pr_reg->pr_aptpl_buf) {
  		pr_err("Unable to allocate pr_reg->pr_aptpl_buf
  ");

  		kmem_cache_free(t10_pr_reg_cache, pr_reg);
  		return NULL;
  	}
  
  	INIT_LIST_HEAD(&pr_reg->pr_reg_list);
  	INIT_LIST_HEAD(&pr_reg->pr_reg_abort_list);
  	INIT_LIST_HEAD(&pr_reg->pr_reg_aptpl_list);
  	INIT_LIST_HEAD(&pr_reg->pr_reg_atp_list);
  	INIT_LIST_HEAD(&pr_reg->pr_reg_atp_mem_list);
  	atomic_set(&pr_reg->pr_res_holders, 0);
  	pr_reg->pr_reg_nacl = nacl;
  	pr_reg->pr_reg_deve = deve;
  	pr_reg->pr_res_mapped_lun = deve->mapped_lun;
  	pr_reg->pr_aptpl_target_lun = deve->se_lun->unpacked_lun;
  	pr_reg->pr_res_key = sa_res_key;
  	pr_reg->pr_reg_all_tg_pt = all_tg_pt;
  	pr_reg->pr_reg_aptpl = aptpl;
  	pr_reg->pr_reg_tg_pt_lun = deve->se_lun;
  	/*
  	 * If an ISID value for this SCSI Initiator Port exists,
  	 * save it to the registration now.
  	 */
  	if (isid != NULL) {
  		pr_reg->pr_reg_bin_isid = get_unaligned_be64(isid);
  		snprintf(pr_reg->pr_reg_isid, PR_REG_ISID_LEN, "%s", isid);
  		pr_reg->isid_present_at_reg = 1;
  	}
  
  	return pr_reg;
  }
  
  static int core_scsi3_lunacl_depend_item(struct se_dev_entry *);
  static void core_scsi3_lunacl_undepend_item(struct se_dev_entry *);
  
  /*
   * Function used for handling PR registrations for ALL_TG_PT=1 and ALL_TG_PT=0
   * modes.
   */
  static struct t10_pr_registration *__core_scsi3_alloc_registration(
  	struct se_device *dev,
  	struct se_node_acl *nacl,
  	struct se_dev_entry *deve,
  	unsigned char *isid,
  	u64 sa_res_key,
  	int all_tg_pt,
  	int aptpl)
  {
  	struct se_dev_entry *deve_tmp;
  	struct se_node_acl *nacl_tmp;
  	struct se_port *port, *port_tmp;
  	struct target_core_fabric_ops *tfo = nacl->se_tpg->se_tpg_tfo;
  	struct t10_pr_registration *pr_reg, *pr_reg_atp, *pr_reg_tmp, *pr_reg_tmp_safe;
  	int ret;
  	/*
  	 * Create a registration for the I_T Nexus upon which the
  	 * PROUT REGISTER was received.
  	 */
  	pr_reg = __core_scsi3_do_alloc_registration(dev, nacl, deve, isid,
  			sa_res_key, all_tg_pt, aptpl);

  	if (!pr_reg)

  		return NULL;
  	/*
  	 * Return pointer to pr_reg for ALL_TG_PT=0
  	 */

  	if (!all_tg_pt)

  		return pr_reg;
  	/*
  	 * Create list of matching SCSI Initiator Port registrations
  	 * for ALL_TG_PT=1
  	 */
  	spin_lock(&dev->se_port_lock);
  	list_for_each_entry_safe(port, port_tmp, &dev->dev_sep_list, sep_list) {
  		atomic_inc(&port->sep_tg_pt_ref_cnt);
  		smp_mb__after_atomic_inc();
  		spin_unlock(&dev->se_port_lock);
  
  		spin_lock_bh(&port->sep_alua_lock);
  		list_for_each_entry(deve_tmp, &port->sep_alua_list,
  					alua_port_list) {
  			/*
  			 * This pointer will be NULL for demo mode MappedLUNs
  			 * that have not been make explict via a ConfigFS
  			 * MappedLUN group for the SCSI Initiator Node ACL.
  			 */

  			if (!deve_tmp->se_lun_acl)

  				continue;
  
  			nacl_tmp = deve_tmp->se_lun_acl->se_lun_nacl;
  			/*
  			 * Skip the matching struct se_node_acl that is allocated
  			 * above..
  			 */
  			if (nacl == nacl_tmp)
  				continue;
  			/*
  			 * Only perform PR registrations for target ports on
  			 * the same fabric module as the REGISTER w/ ALL_TG_PT=1
  			 * arrived.
  			 */
  			if (tfo != nacl_tmp->se_tpg->se_tpg_tfo)
  				continue;
  			/*
  			 * Look for a matching Initiator Node ACL in ASCII format
  			 */
  			if (strcmp(nacl->initiatorname, nacl_tmp->initiatorname))
  				continue;
  
  			atomic_inc(&deve_tmp->pr_ref_count);
  			smp_mb__after_atomic_inc();
  			spin_unlock_bh(&port->sep_alua_lock);
  			/*
  			 * Grab a configfs group dependency that is released
  			 * for the exception path at label out: below, or upon
  			 * completion of adding ALL_TG_PT=1 registrations in
  			 * __core_scsi3_add_registration()
  			 */
  			ret = core_scsi3_lunacl_depend_item(deve_tmp);
  			if (ret < 0) {

  				pr_err("core_scsi3_lunacl_depend"

  						"_item() failed
  ");
  				atomic_dec(&port->sep_tg_pt_ref_cnt);
  				smp_mb__after_atomic_dec();
  				atomic_dec(&deve_tmp->pr_ref_count);
  				smp_mb__after_atomic_dec();
  				goto out;
  			}
  			/*
  			 * Located a matching SCSI Initiator Port on a different
  			 * port, allocate the pr_reg_atp and attach it to the
  			 * pr_reg->pr_reg_atp_list that will be processed once
  			 * the original *pr_reg is processed in
  			 * __core_scsi3_add_registration()
  			 */
  			pr_reg_atp = __core_scsi3_do_alloc_registration(dev,
  						nacl_tmp, deve_tmp, NULL,
  						sa_res_key, all_tg_pt, aptpl);

  			if (!pr_reg_atp) {

  				atomic_dec(&port->sep_tg_pt_ref_cnt);
  				smp_mb__after_atomic_dec();
  				atomic_dec(&deve_tmp->pr_ref_count);
  				smp_mb__after_atomic_dec();
  				core_scsi3_lunacl_undepend_item(deve_tmp);
  				goto out;
  			}
  
  			list_add_tail(&pr_reg_atp->pr_reg_atp_mem_list,
  				      &pr_reg->pr_reg_atp_list);
  			spin_lock_bh(&port->sep_alua_lock);
  		}
  		spin_unlock_bh(&port->sep_alua_lock);
  
  		spin_lock(&dev->se_port_lock);
  		atomic_dec(&port->sep_tg_pt_ref_cnt);
  		smp_mb__after_atomic_dec();
  	}
  	spin_unlock(&dev->se_port_lock);
  
  	return pr_reg;
  out:
  	list_for_each_entry_safe(pr_reg_tmp, pr_reg_tmp_safe,
  			&pr_reg->pr_reg_atp_list, pr_reg_atp_mem_list) {
  		list_del(&pr_reg_tmp->pr_reg_atp_mem_list);
  		core_scsi3_lunacl_undepend_item(pr_reg_tmp->pr_reg_deve);
  		kmem_cache_free(t10_pr_reg_cache, pr_reg_tmp);
  	}
  	kmem_cache_free(t10_pr_reg_cache, pr_reg);
  	return NULL;
  }
  
  int core_scsi3_alloc_aptpl_registration(

  	struct t10_reservation *pr_tmpl,

  	u64 sa_res_key,
  	unsigned char *i_port,
  	unsigned char *isid,
  	u32 mapped_lun,
  	unsigned char *t_port,
  	u16 tpgt,
  	u32 target_lun,
  	int res_holder,
  	int all_tg_pt,
  	u8 type)
  {
  	struct t10_pr_registration *pr_reg;

  	if (!i_port || !t_port || !sa_res_key) {
  		pr_err("Illegal parameters for APTPL registration
  ");

  		return -EINVAL;

  	}
  
  	pr_reg = kmem_cache_zalloc(t10_pr_reg_cache, GFP_KERNEL);

  	if (!pr_reg) {
  		pr_err("Unable to allocate struct t10_pr_registration
  ");

  		return -ENOMEM;

  	}
  	pr_reg->pr_aptpl_buf = kzalloc(pr_tmpl->pr_aptpl_buf_len, GFP_KERNEL);
  
  	INIT_LIST_HEAD(&pr_reg->pr_reg_list);
  	INIT_LIST_HEAD(&pr_reg->pr_reg_abort_list);
  	INIT_LIST_HEAD(&pr_reg->pr_reg_aptpl_list);
  	INIT_LIST_HEAD(&pr_reg->pr_reg_atp_list);
  	INIT_LIST_HEAD(&pr_reg->pr_reg_atp_mem_list);
  	atomic_set(&pr_reg->pr_res_holders, 0);
  	pr_reg->pr_reg_nacl = NULL;
  	pr_reg->pr_reg_deve = NULL;
  	pr_reg->pr_res_mapped_lun = mapped_lun;
  	pr_reg->pr_aptpl_target_lun = target_lun;
  	pr_reg->pr_res_key = sa_res_key;
  	pr_reg->pr_reg_all_tg_pt = all_tg_pt;
  	pr_reg->pr_reg_aptpl = 1;
  	pr_reg->pr_reg_tg_pt_lun = NULL;
  	pr_reg->pr_res_scope = 0; /* Always LUN_SCOPE */
  	pr_reg->pr_res_type = type;
  	/*
  	 * If an ISID value had been saved in APTPL metadata for this
  	 * SCSI Initiator Port, restore it now.
  	 */
  	if (isid != NULL) {
  		pr_reg->pr_reg_bin_isid = get_unaligned_be64(isid);
  		snprintf(pr_reg->pr_reg_isid, PR_REG_ISID_LEN, "%s", isid);
  		pr_reg->isid_present_at_reg = 1;
  	}
  	/*
  	 * Copy the i_port and t_port information from caller.
  	 */
  	snprintf(pr_reg->pr_iport, PR_APTPL_MAX_IPORT_LEN, "%s", i_port);
  	snprintf(pr_reg->pr_tport, PR_APTPL_MAX_TPORT_LEN, "%s", t_port);
  	pr_reg->pr_reg_tpgt = tpgt;
  	/*
  	 * Set pr_res_holder from caller, the pr_reg who is the reservation
  	 * holder will get it's pointer set in core_scsi3_aptpl_reserve() once
  	 * the Initiator Node LUN ACL from the fabric module is created for
  	 * this registration.
  	 */
  	pr_reg->pr_res_holder = res_holder;
  
  	list_add_tail(&pr_reg->pr_reg_aptpl_list, &pr_tmpl->aptpl_reg_list);

  	pr_debug("SPC-3 PR APTPL Successfully added registration%s from"

  			" metadata
  ", (res_holder) ? "+reservation" : "");
  	return 0;
  }
  
  static void core_scsi3_aptpl_reserve(
  	struct se_device *dev,
  	struct se_portal_group *tpg,
  	struct se_node_acl *node_acl,
  	struct t10_pr_registration *pr_reg)
  {
  	char i_buf[PR_REG_ISID_ID_LEN];
  	int prf_isid;
  
  	memset(i_buf, 0, PR_REG_ISID_ID_LEN);
  	prf_isid = core_pr_dump_initiator_port(pr_reg, &i_buf[0],
  				PR_REG_ISID_ID_LEN);
  
  	spin_lock(&dev->dev_reservation_lock);
  	dev->dev_pr_res_holder = pr_reg;
  	spin_unlock(&dev->dev_reservation_lock);

  	pr_debug("SPC-3 PR [%s] Service Action: APTPL RESERVE created"

  		" new reservation holder TYPE: %s ALL_TG_PT: %d
  ",

  		tpg->se_tpg_tfo->get_fabric_name(),

  		core_scsi3_pr_dump_type(pr_reg->pr_res_type),
  		(pr_reg->pr_reg_all_tg_pt) ? 1 : 0);

  	pr_debug("SPC-3 PR [%s] RESERVE Node: %s%s
  ",

  		tpg->se_tpg_tfo->get_fabric_name(), node_acl->initiatorname,

  		(prf_isid) ? &i_buf[0] : "");
  }
  
  static void __core_scsi3_add_registration(struct se_device *, struct se_node_acl *,
  				struct t10_pr_registration *, int, int);
  
  static int __core_scsi3_check_aptpl_registration(
  	struct se_device *dev,
  	struct se_portal_group *tpg,
  	struct se_lun *lun,
  	u32 target_lun,
  	struct se_node_acl *nacl,
  	struct se_dev_entry *deve)
  {
  	struct t10_pr_registration *pr_reg, *pr_reg_tmp;

  	struct t10_reservation *pr_tmpl = &dev->se_sub_dev->t10_pr;

  	unsigned char i_port[PR_APTPL_MAX_IPORT_LEN];
  	unsigned char t_port[PR_APTPL_MAX_TPORT_LEN];
  	u16 tpgt;
  
  	memset(i_port, 0, PR_APTPL_MAX_IPORT_LEN);
  	memset(t_port, 0, PR_APTPL_MAX_TPORT_LEN);
  	/*
  	 * Copy Initiator Port information from struct se_node_acl
  	 */
  	snprintf(i_port, PR_APTPL_MAX_IPORT_LEN, "%s", nacl->initiatorname);
  	snprintf(t_port, PR_APTPL_MAX_TPORT_LEN, "%s",

  			tpg->se_tpg_tfo->tpg_get_wwn(tpg));
  	tpgt = tpg->se_tpg_tfo->tpg_get_tag(tpg);

  	/*
  	 * Look for the matching registrations+reservation from those
  	 * created from APTPL metadata.  Note that multiple registrations
  	 * may exist for fabrics that use ISIDs in their SCSI Initiator Port
  	 * TransportIDs.
  	 */
  	spin_lock(&pr_tmpl->aptpl_reg_lock);
  	list_for_each_entry_safe(pr_reg, pr_reg_tmp, &pr_tmpl->aptpl_reg_list,
  				pr_reg_aptpl_list) {

  		if (!strcmp(pr_reg->pr_iport, i_port) &&

  		     (pr_reg->pr_res_mapped_lun == deve->mapped_lun) &&
  		    !(strcmp(pr_reg->pr_tport, t_port)) &&
  		     (pr_reg->pr_reg_tpgt == tpgt) &&
  		     (pr_reg->pr_aptpl_target_lun == target_lun)) {
  
  			pr_reg->pr_reg_nacl = nacl;
  			pr_reg->pr_reg_deve = deve;
  			pr_reg->pr_reg_tg_pt_lun = lun;
  
  			list_del(&pr_reg->pr_reg_aptpl_list);
  			spin_unlock(&pr_tmpl->aptpl_reg_lock);
  			/*
  			 * At this point all of the pointers in *pr_reg will
  			 * be setup, so go ahead and add the registration.
  			 */
  
  			__core_scsi3_add_registration(dev, nacl, pr_reg, 0, 0);
  			/*
  			 * If this registration is the reservation holder,
  			 * make that happen now..
  			 */
  			if (pr_reg->pr_res_holder)
  				core_scsi3_aptpl_reserve(dev, tpg,
  						nacl, pr_reg);
  			/*
  			 * Reenable pr_aptpl_active to accept new metadata
  			 * updates once the SCSI device is active again..
  			 */
  			spin_lock(&pr_tmpl->aptpl_reg_lock);
  			pr_tmpl->pr_aptpl_active = 1;
  		}
  	}
  	spin_unlock(&pr_tmpl->aptpl_reg_lock);
  
  	return 0;
  }
  
  int core_scsi3_check_aptpl_registration(
  	struct se_device *dev,
  	struct se_portal_group *tpg,
  	struct se_lun *lun,
  	struct se_lun_acl *lun_acl)
  {

  	struct se_subsystem_dev *su_dev = dev->se_sub_dev;

  	struct se_node_acl *nacl = lun_acl->se_lun_nacl;
  	struct se_dev_entry *deve = &nacl->device_list[lun_acl->mapped_lun];

  	if (su_dev->t10_pr.res_type != SPC3_PERSISTENT_RESERVATIONS)

  		return 0;
  
  	return __core_scsi3_check_aptpl_registration(dev, tpg, lun,
  				lun->unpacked_lun, nacl, deve);
  }
  
  static void __core_scsi3_dump_registration(
  	struct target_core_fabric_ops *tfo,
  	struct se_device *dev,
  	struct se_node_acl *nacl,
  	struct t10_pr_registration *pr_reg,
  	int register_type)
  {
  	struct se_portal_group *se_tpg = nacl->se_tpg;
  	char i_buf[PR_REG_ISID_ID_LEN];
  	int prf_isid;
  
  	memset(&i_buf[0], 0, PR_REG_ISID_ID_LEN);
  	prf_isid = core_pr_dump_initiator_port(pr_reg, &i_buf[0],
  				PR_REG_ISID_ID_LEN);

  	pr_debug("SPC-3 PR [%s] Service Action: REGISTER%s Initiator"

  		" Node: %s%s
  ", tfo->get_fabric_name(), (register_type == 2) ?
  		"_AND_MOVE" : (register_type == 1) ?
  		"_AND_IGNORE_EXISTING_KEY" : "", nacl->initiatorname,
  		(prf_isid) ? i_buf : "");

  	pr_debug("SPC-3 PR [%s] registration on Target Port: %s,0x%04x
  ",

  		 tfo->get_fabric_name(), tfo->tpg_get_wwn(se_tpg),
  		tfo->tpg_get_tag(se_tpg));

  	pr_debug("SPC-3 PR [%s] for %s TCM Subsystem %s Object Target"

  		" Port(s)
  ",  tfo->get_fabric_name(),
  		(pr_reg->pr_reg_all_tg_pt) ? "ALL" : "SINGLE",

  		dev->transport->name);

  	pr_debug("SPC-3 PR [%s] SA Res Key: 0x%016Lx PRgeneration:"

  		" 0x%08x  APTPL: %d
  ", tfo->get_fabric_name(),
  		pr_reg->pr_res_key, pr_reg->pr_res_generation,
  		pr_reg->pr_reg_aptpl);
  }
  
  /*
   * this function can be called with struct se_device->dev_reservation_lock
   * when register_move = 1
   */
  static void __core_scsi3_add_registration(
  	struct se_device *dev,
  	struct se_node_acl *nacl,
  	struct t10_pr_registration *pr_reg,
  	int register_type,
  	int register_move)
  {

  	struct se_subsystem_dev *su_dev = dev->se_sub_dev;

  	struct target_core_fabric_ops *tfo = nacl->se_tpg->se_tpg_tfo;
  	struct t10_pr_registration *pr_reg_tmp, *pr_reg_tmp_safe;

  	struct t10_reservation *pr_tmpl = &dev->se_sub_dev->t10_pr;

  
  	/*
  	 * Increment PRgeneration counter for struct se_device upon a successful
  	 * REGISTER, see spc4r17 section 6.3.2 READ_KEYS service action
  	 *
  	 * Also, when register_move = 1 for PROUT REGISTER_AND_MOVE service
  	 * action, the struct se_device->dev_reservation_lock will already be held,
  	 * so we do not call core_scsi3_pr_generation() which grabs the lock
  	 * for the REGISTER.
  	 */
  	pr_reg->pr_res_generation = (register_move) ?

  			su_dev->t10_pr.pr_generation++ :

  			core_scsi3_pr_generation(dev);
  
  	spin_lock(&pr_tmpl->registration_lock);
  	list_add_tail(&pr_reg->pr_reg_list, &pr_tmpl->registration_list);
  	pr_reg->pr_reg_deve->def_pr_registered = 1;
  
  	__core_scsi3_dump_registration(tfo, dev, nacl, pr_reg, register_type);
  	spin_unlock(&pr_tmpl->registration_lock);
  	/*
  	 * Skip extra processing for ALL_TG_PT=0 or REGISTER_AND_MOVE.
  	 */

  	if (!pr_reg->pr_reg_all_tg_pt || register_move)

  		return;
  	/*
  	 * Walk pr_reg->pr_reg_atp_list and add registrations for ALL_TG_PT=1
  	 * allocated in __core_scsi3_alloc_registration()
  	 */
  	list_for_each_entry_safe(pr_reg_tmp, pr_reg_tmp_safe,
  			&pr_reg->pr_reg_atp_list, pr_reg_atp_mem_list) {
  		list_del(&pr_reg_tmp->pr_reg_atp_mem_list);
  
  		pr_reg_tmp->pr_res_generation = core_scsi3_pr_generation(dev);
  
  		spin_lock(&pr_tmpl->registration_lock);
  		list_add_tail(&pr_reg_tmp->pr_reg_list,
  			      &pr_tmpl->registration_list);
  		pr_reg_tmp->pr_reg_deve->def_pr_registered = 1;
  
  		__core_scsi3_dump_registration(tfo, dev,
  				pr_reg_tmp->pr_reg_nacl, pr_reg_tmp,
  				register_type);
  		spin_unlock(&pr_tmpl->registration_lock);
  		/*
  		 * Drop configfs group dependency reference from
  		 * __core_scsi3_alloc_registration()
  		 */
  		core_scsi3_lunacl_undepend_item(pr_reg_tmp->pr_reg_deve);
  	}
  }
  
  static int core_scsi3_alloc_registration(
  	struct se_device *dev,
  	struct se_node_acl *nacl,
  	struct se_dev_entry *deve,
  	unsigned char *isid,
  	u64 sa_res_key,
  	int all_tg_pt,
  	int aptpl,
  	int register_type,
  	int register_move)
  {
  	struct t10_pr_registration *pr_reg;
  
  	pr_reg = __core_scsi3_alloc_registration(dev, nacl, deve, isid,
  			sa_res_key, all_tg_pt, aptpl);

  	if (!pr_reg)

  		return -EPERM;

  
  	__core_scsi3_add_registration(dev, nacl, pr_reg,
  			register_type, register_move);
  	return 0;
  }
  
  static struct t10_pr_registration *__core_scsi3_locate_pr_reg(
  	struct se_device *dev,
  	struct se_node_acl *nacl,
  	unsigned char *isid)
  {

  	struct t10_reservation *pr_tmpl = &dev->se_sub_dev->t10_pr;

  	struct t10_pr_registration *pr_reg, *pr_reg_tmp;
  	struct se_portal_group *tpg;
  
  	spin_lock(&pr_tmpl->registration_lock);
  	list_for_each_entry_safe(pr_reg, pr_reg_tmp,
  			&pr_tmpl->registration_list, pr_reg_list) {
  		/*
  		 * First look for a matching struct se_node_acl
  		 */
  		if (pr_reg->pr_reg_nacl != nacl)
  			continue;
  
  		tpg = pr_reg->pr_reg_nacl->se_tpg;
  		/*
  		 * If this registration does NOT contain a fabric provided
  		 * ISID, then we have found a match.
  		 */

  		if (!pr_reg->isid_present_at_reg) {

  			/*
  			 * Determine if this SCSI device server requires that
  			 * SCSI Intiatior TransportID w/ ISIDs is enforced
  			 * for fabric modules (iSCSI) requiring them.
  			 */

  			if (tpg->se_tpg_tfo->sess_get_initiator_sid != NULL) {
  				if (dev->se_sub_dev->se_dev_attrib.enforce_pr_isids)

  					continue;
  			}
  			atomic_inc(&pr_reg->pr_res_holders);
  			smp_mb__after_atomic_inc();
  			spin_unlock(&pr_tmpl->registration_lock);
  			return pr_reg;
  		}
  		/*
  		 * If the *pr_reg contains a fabric defined ISID for multi-value
  		 * SCSI Initiator Port TransportIDs, then we expect a valid
  		 * matching ISID to be provided by the local SCSI Initiator Port.
  		 */

  		if (!isid)

  			continue;
  		if (strcmp(isid, pr_reg->pr_reg_isid))
  			continue;
  
  		atomic_inc(&pr_reg->pr_res_holders);
  		smp_mb__after_atomic_inc();
  		spin_unlock(&pr_tmpl->registration_lock);
  		return pr_reg;
  	}
  	spin_unlock(&pr_tmpl->registration_lock);
  
  	return NULL;
  }
  
  static struct t10_pr_registration *core_scsi3_locate_pr_reg(
  	struct se_device *dev,
  	struct se_node_acl *nacl,
  	struct se_session *sess)
  {
  	struct se_portal_group *tpg = nacl->se_tpg;
  	unsigned char buf[PR_REG_ISID_LEN], *isid_ptr = NULL;

  	if (tpg->se_tpg_tfo->sess_get_initiator_sid != NULL) {

  		memset(&buf[0], 0, PR_REG_ISID_LEN);

  		tpg->se_tpg_tfo->sess_get_initiator_sid(sess, &buf[0],

  					PR_REG_ISID_LEN);
  		isid_ptr = &buf[0];
  	}
  
  	return __core_scsi3_locate_pr_reg(dev, nacl, isid_ptr);
  }
  
  static void core_scsi3_put_pr_reg(struct t10_pr_registration *pr_reg)
  {
  	atomic_dec(&pr_reg->pr_res_holders);
  	smp_mb__after_atomic_dec();
  }
  
  static int core_scsi3_check_implict_release(
  	struct se_device *dev,
  	struct t10_pr_registration *pr_reg)
  {
  	struct se_node_acl *nacl = pr_reg->pr_reg_nacl;
  	struct t10_pr_registration *pr_res_holder;
  	int ret = 0;
  
  	spin_lock(&dev->dev_reservation_lock);
  	pr_res_holder = dev->dev_pr_res_holder;

  	if (!pr_res_holder) {

  		spin_unlock(&dev->dev_reservation_lock);
  		return ret;
  	}
  	if (pr_res_holder == pr_reg) {
  		/*
  		 * Perform an implict RELEASE if the registration that
  		 * is being released is holding the reservation.
  		 *
  		 * From spc4r17, section 5.7.11.1:
  		 *
  		 * e) If the I_T nexus is the persistent reservation holder
  		 *    and the persistent reservation is not an all registrants
  		 *    type, then a PERSISTENT RESERVE OUT command with REGISTER
  		 *    service action or REGISTER AND  IGNORE EXISTING KEY
  		 *    service action with the SERVICE ACTION RESERVATION KEY
  		 *    field set to zero (see 5.7.11.3).
  		 */
  		__core_scsi3_complete_pro_release(dev, nacl, pr_reg, 0);
  		ret = 1;
  		/*
  		 * For 'All Registrants' reservation types, all existing
  		 * registrations are still processed as reservation holders
  		 * in core_scsi3_pr_seq_non_holder() after the initial
  		 * reservation holder is implictly released here.
  		 */
  	} else if (pr_reg->pr_reg_all_tg_pt &&
  		  (!strcmp(pr_res_holder->pr_reg_nacl->initiatorname,
  			  pr_reg->pr_reg_nacl->initiatorname)) &&
  		  (pr_res_holder->pr_res_key == pr_reg->pr_res_key)) {

  		pr_err("SPC-3 PR: Unable to perform ALL_TG_PT=1"

  			" UNREGISTER while existing reservation with matching"
  			" key 0x%016Lx is present from another SCSI Initiator"
  			" Port
  ", pr_reg->pr_res_key);

  		ret = -EPERM;

  	}
  	spin_unlock(&dev->dev_reservation_lock);
  
  	return ret;
  }
  
  /*

   * Called with struct t10_reservation->registration_lock held.

   */
  static void __core_scsi3_free_registration(
  	struct se_device *dev,
  	struct t10_pr_registration *pr_reg,
  	struct list_head *preempt_and_abort_list,
  	int dec_holders)
  {
  	struct target_core_fabric_ops *tfo =
  			pr_reg->pr_reg_nacl->se_tpg->se_tpg_tfo;

  	struct t10_reservation *pr_tmpl = &dev->se_sub_dev->t10_pr;

  	char i_buf[PR_REG_ISID_ID_LEN];
  	int prf_isid;
  
  	memset(i_buf, 0, PR_REG_ISID_ID_LEN);
  	prf_isid = core_pr_dump_initiator_port(pr_reg, &i_buf[0],
  				PR_REG_ISID_ID_LEN);
  
  	pr_reg->pr_reg_deve->def_pr_registered = 0;
  	pr_reg->pr_reg_deve->pr_res_key = 0;
  	list_del(&pr_reg->pr_reg_list);
  	/*
  	 * Caller accessing *pr_reg using core_scsi3_locate_pr_reg(),
  	 * so call core_scsi3_put_pr_reg() to decrement our reference.
  	 */
  	if (dec_holders)
  		core_scsi3_put_pr_reg(pr_reg);
  	/*
  	 * Wait until all reference from any other I_T nexuses for this
  	 * *pr_reg have been released.  Because list_del() is called above,
  	 * the last core_scsi3_put_pr_reg(pr_reg) will release this reference
  	 * count back to zero, and we release *pr_reg.
  	 */
  	while (atomic_read(&pr_reg->pr_res_holders) != 0) {
  		spin_unlock(&pr_tmpl->registration_lock);

  		pr_debug("SPC-3 PR [%s] waiting for pr_res_holders
  ",

  				tfo->get_fabric_name());
  		cpu_relax();
  		spin_lock(&pr_tmpl->registration_lock);
  	}

  	pr_debug("SPC-3 PR [%s] Service Action: UNREGISTER Initiator"

  		" Node: %s%s
  ", tfo->get_fabric_name(),
  		pr_reg->pr_reg_nacl->initiatorname,
  		(prf_isid) ? &i_buf[0] : "");

  	pr_debug("SPC-3 PR [%s] for %s TCM Subsystem %s Object Target"

  		" Port(s)
  ", tfo->get_fabric_name(),
  		(pr_reg->pr_reg_all_tg_pt) ? "ALL" : "SINGLE",

  		dev->transport->name);

  	pr_debug("SPC-3 PR [%s] SA Res Key: 0x%016Lx PRgeneration:"

  		" 0x%08x
  ", tfo->get_fabric_name(), pr_reg->pr_res_key,
  		pr_reg->pr_res_generation);

  	if (!preempt_and_abort_list) {

  		pr_reg->pr_reg_deve = NULL;
  		pr_reg->pr_reg_nacl = NULL;
  		kfree(pr_reg->pr_aptpl_buf);
  		kmem_cache_free(t10_pr_reg_cache, pr_reg);
  		return;
  	}
  	/*
  	 * For PREEMPT_AND_ABORT, the list of *pr_reg in preempt_and_abort_list
  	 * are released once the ABORT_TASK_SET has completed..
  	 */
  	list_add_tail(&pr_reg->pr_reg_abort_list, preempt_and_abort_list);
  }
  
  void core_scsi3_free_pr_reg_from_nacl(
  	struct se_device *dev,
  	struct se_node_acl *nacl)
  {

  	struct t10_reservation *pr_tmpl = &dev->se_sub_dev->t10_pr;

  	struct t10_pr_registration *pr_reg, *pr_reg_tmp, *pr_res_holder;
  	/*
  	 * If the passed se_node_acl matches the reservation holder,
  	 * release the reservation.
  	 */
  	spin_lock(&dev->dev_reservation_lock);
  	pr_res_holder = dev->dev_pr_res_holder;
  	if ((pr_res_holder != NULL) &&
  	    (pr_res_holder->pr_reg_nacl == nacl))
  		__core_scsi3_complete_pro_release(dev, nacl, pr_res_holder, 0);
  	spin_unlock(&dev->dev_reservation_lock);
  	/*
  	 * Release any registration associated with the struct se_node_acl.
  	 */
  	spin_lock(&pr_tmpl->registration_lock);
  	list_for_each_entry_safe(pr_reg, pr_reg_tmp,
  			&pr_tmpl->registration_list, pr_reg_list) {
  
  		if (pr_reg->pr_reg_nacl != nacl)
  			continue;
  
  		__core_scsi3_free_registration(dev, pr_reg, NULL, 0);
  	}
  	spin_unlock(&pr_tmpl->registration_lock);
  }
  
  void core_scsi3_free_all_registrations(
  	struct se_device *dev)
  {

  	struct t10_reservation *pr_tmpl = &dev->se_sub_dev->t10_pr;

  	struct t10_pr_registration *pr_reg, *pr_reg_tmp, *pr_res_holder;
  
  	spin_lock(&dev->dev_reservation_lock);
  	pr_res_holder = dev->dev_pr_res_holder;
  	if (pr_res_holder != NULL) {
  		struct se_node_acl *pr_res_nacl = pr_res_holder->pr_reg_nacl;
  		__core_scsi3_complete_pro_release(dev, pr_res_nacl,
  				pr_res_holder, 0);
  	}
  	spin_unlock(&dev->dev_reservation_lock);
  
  	spin_lock(&pr_tmpl->registration_lock);
  	list_for_each_entry_safe(pr_reg, pr_reg_tmp,
  			&pr_tmpl->registration_list, pr_reg_list) {
  
  		__core_scsi3_free_registration(dev, pr_reg, NULL, 0);
  	}
  	spin_unlock(&pr_tmpl->registration_lock);
  
  	spin_lock(&pr_tmpl->aptpl_reg_lock);
  	list_for_each_entry_safe(pr_reg, pr_reg_tmp, &pr_tmpl->aptpl_reg_list,
  				pr_reg_aptpl_list) {
  		list_del(&pr_reg->pr_reg_aptpl_list);
  		kfree(pr_reg->pr_aptpl_buf);
  		kmem_cache_free(t10_pr_reg_cache, pr_reg);
  	}
  	spin_unlock(&pr_tmpl->aptpl_reg_lock);
  }
  
  static int core_scsi3_tpg_depend_item(struct se_portal_group *tpg)
  {

  	return configfs_depend_item(tpg->se_tpg_tfo->tf_subsys,

  			&tpg->tpg_group.cg_item);
  }
  
  static void core_scsi3_tpg_undepend_item(struct se_portal_group *tpg)
  {

  	configfs_undepend_item(tpg->se_tpg_tfo->tf_subsys,

  			&tpg->tpg_group.cg_item);
  
  	atomic_dec(&tpg->tpg_pr_ref_count);
  	smp_mb__after_atomic_dec();
  }
  
  static int core_scsi3_nodeacl_depend_item(struct se_node_acl *nacl)
  {
  	struct se_portal_group *tpg = nacl->se_tpg;
  
  	if (nacl->dynamic_node_acl)
  		return 0;

  	return configfs_depend_item(tpg->se_tpg_tfo->tf_subsys,

  			&nacl->acl_group.cg_item);
  }
  
  static void core_scsi3_nodeacl_undepend_item(struct se_node_acl *nacl)
  {
  	struct se_portal_group *tpg = nacl->se_tpg;
  
  	if (nacl->dynamic_node_acl) {
  		atomic_dec(&nacl->acl_pr_ref_count);
  		smp_mb__after_atomic_dec();
  		return;
  	}

  	configfs_undepend_item(tpg->se_tpg_tfo->tf_subsys,

  			&nacl->acl_group.cg_item);
  
  	atomic_dec(&nacl->acl_pr_ref_count);
  	smp_mb__after_atomic_dec();
  }
  
  static int core_scsi3_lunacl_depend_item(struct se_dev_entry *se_deve)
  {
  	struct se_lun_acl *lun_acl = se_deve->se_lun_acl;
  	struct se_node_acl *nacl;
  	struct se_portal_group *tpg;
  	/*
  	 * For nacl->dynamic_node_acl=1
  	 */

  	if (!lun_acl)

  		return 0;
  
  	nacl = lun_acl->se_lun_nacl;
  	tpg = nacl->se_tpg;

  	return configfs_depend_item(tpg->se_tpg_tfo->tf_subsys,

  			&lun_acl->se_lun_group.cg_item);
  }
  
  static void core_scsi3_lunacl_undepend_item(struct se_dev_entry *se_deve)
  {
  	struct se_lun_acl *lun_acl = se_deve->se_lun_acl;
  	struct se_node_acl *nacl;
  	struct se_portal_group *tpg;
  	/*
  	 * For nacl->dynamic_node_acl=1
  	 */

  	if (!lun_acl) {

  		atomic_dec(&se_deve->pr_ref_count);
  		smp_mb__after_atomic_dec();
  		return;
  	}
  	nacl = lun_acl->se_lun_nacl;
  	tpg = nacl->se_tpg;

  	configfs_undepend_item(tpg->se_tpg_tfo->tf_subsys,

  			&lun_acl->se_lun_group.cg_item);
  
  	atomic_dec(&se_deve->pr_ref_count);
  	smp_mb__after_atomic_dec();
  }
  
  static int core_scsi3_decode_spec_i_port(
  	struct se_cmd *cmd,
  	struct se_portal_group *tpg,
  	unsigned char *l_isid,
  	u64 sa_res_key,
  	int all_tg_pt,
  	int aptpl)
  {

  	struct se_device *dev = cmd->se_dev;

  	struct se_port *tmp_port;
  	struct se_portal_group *dest_tpg = NULL, *tmp_tpg;

  	struct se_session *se_sess = cmd->se_sess;

  	struct se_node_acl *dest_node_acl = NULL;
  	struct se_dev_entry *dest_se_deve = NULL, *local_se_deve;
  	struct t10_pr_registration *dest_pr_reg, *local_pr_reg, *pr_reg_e;
  	struct t10_pr_registration *pr_reg_tmp, *pr_reg_tmp_safe;
  	struct list_head tid_dest_list;
  	struct pr_transport_id_holder *tidh_new, *tidh, *tidh_tmp;
  	struct target_core_fabric_ops *tmp_tf_ops;

  	unsigned char *buf;

  	unsigned char *ptr, *i_str = NULL, proto_ident, tmp_proto_ident;
  	char *iport_ptr = NULL, dest_iport[64], i_buf[PR_REG_ISID_ID_LEN];
  	u32 tpdl, tid_len = 0;
  	int ret, dest_local_nexus, prf_isid;
  	u32 dest_rtpi = 0;
  
  	memset(dest_iport, 0, 64);
  	INIT_LIST_HEAD(&tid_dest_list);
  
  	local_se_deve = &se_sess->se_node_acl->device_list[cmd->orig_fe_lun];
  	/*
  	 * Allocate a struct pr_transport_id_holder and setup the
  	 * local_node_acl and local_se_deve pointers and add to
  	 * struct list_head tid_dest_list for add registration
  	 * processing in the loop of tid_dest_list below.
  	 */
  	tidh_new = kzalloc(sizeof(struct pr_transport_id_holder), GFP_KERNEL);

  	if (!tidh_new) {
  		pr_err("Unable to allocate tidh_new
  ");

  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  		return -EINVAL;

  	}
  	INIT_LIST_HEAD(&tidh_new->dest_list);
  	tidh_new->dest_tpg = tpg;
  	tidh_new->dest_node_acl = se_sess->se_node_acl;
  	tidh_new->dest_se_deve = local_se_deve;

  	local_pr_reg = __core_scsi3_alloc_registration(cmd->se_dev,

  				se_sess->se_node_acl, local_se_deve, l_isid,
  				sa_res_key, all_tg_pt, aptpl);

  	if (!local_pr_reg) {

  		kfree(tidh_new);

  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  		return -ENOMEM;

  	}
  	tidh_new->dest_pr_reg = local_pr_reg;
  	/*
  	 * The local I_T nexus does not hold any configfs dependances,
  	 * so we set tid_h->dest_local_nexus=1 to prevent the
  	 * configfs_undepend_item() calls in the tid_dest_list loops below.
  	 */
  	tidh_new->dest_local_nexus = 1;
  	list_add_tail(&tidh_new->dest_list, &tid_dest_list);

  
  	buf = transport_kmap_first_data_page(cmd);

  	/*
  	 * For a PERSISTENT RESERVE OUT specify initiator ports payload,
  	 * first extract TransportID Parameter Data Length, and make sure
  	 * the value matches up to the SCSI expected data transfer length.
  	 */
  	tpdl = (buf[24] & 0xff) << 24;
  	tpdl |= (buf[25] & 0xff) << 16;
  	tpdl |= (buf[26] & 0xff) << 8;
  	tpdl |= buf[27] & 0xff;
  
  	if ((tpdl + 28) != cmd->data_length) {

  		pr_err("SPC-3 PR: Illegal tpdl: %u + 28 byte header"

  			" does not equal CDB data_length: %u
  ", tpdl,
  			cmd->data_length);

  		cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
  		ret = -EINVAL;

  		goto out;
  	}
  	/*
  	 * Start processing the received transport IDs using the
  	 * receiving I_T Nexus portal's fabric dependent methods to
  	 * obtain the SCSI Initiator Port/Device Identifiers.
  	 */
  	ptr = &buf[28];
  
  	while (tpdl > 0) {
  		proto_ident = (ptr[0] & 0x0f);
  		dest_tpg = NULL;
  
  		spin_lock(&dev->se_port_lock);
  		list_for_each_entry(tmp_port, &dev->dev_sep_list, sep_list) {
  			tmp_tpg = tmp_port->sep_tpg;

  			if (!tmp_tpg)

  				continue;

  			tmp_tf_ops = tmp_tpg->se_tpg_tfo;

  			if (!tmp_tf_ops)

  				continue;

  			if (!tmp_tf_ops->get_fabric_proto_ident ||
  			    !tmp_tf_ops->tpg_parse_pr_out_transport_id)

  				continue;
  			/*
  			 * Look for the matching proto_ident provided by
  			 * the received TransportID
  			 */
  			tmp_proto_ident = tmp_tf_ops->get_fabric_proto_ident(tmp_tpg);
  			if (tmp_proto_ident != proto_ident)
  				continue;
  			dest_rtpi = tmp_port->sep_rtpi;
  
  			i_str = tmp_tf_ops->tpg_parse_pr_out_transport_id(
  					tmp_tpg, (const char *)ptr, &tid_len,
  					&iport_ptr);

  			if (!i_str)

  				continue;
  
  			atomic_inc(&tmp_tpg->tpg_pr_ref_count);
  			smp_mb__after_atomic_inc();
  			spin_unlock(&dev->se_port_lock);
  
  			ret = core_scsi3_tpg_depend_item(tmp_tpg);
  			if (ret != 0) {

  				pr_err(" core_scsi3_tpg_depend_item()"

  					" for tmp_tpg
  ");
  				atomic_dec(&tmp_tpg->tpg_pr_ref_count);
  				smp_mb__after_atomic_dec();

  				cmd->scsi_sense_reason =
  					TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  				ret = -EINVAL;

  				goto out;
  			}
  			/*
  			 * Locate the desination initiator ACL to be registered
  			 * from the decoded fabric module specific TransportID
  			 * at *i_str.
  			 */

  			spin_lock_irq(&tmp_tpg->acl_node_lock);

  			dest_node_acl = __core_tpg_get_initiator_node_acl(
  						tmp_tpg, i_str);
  			if (dest_node_acl) {
  				atomic_inc(&dest_node_acl->acl_pr_ref_count);
  				smp_mb__after_atomic_inc();
  			}

  			spin_unlock_irq(&tmp_tpg->acl_node_lock);

  			if (!dest_node_acl) {

  				core_scsi3_tpg_undepend_item(tmp_tpg);
  				spin_lock(&dev->se_port_lock);
  				continue;
  			}
  
  			ret = core_scsi3_nodeacl_depend_item(dest_node_acl);
  			if (ret != 0) {

  				pr_err("configfs_depend_item() failed"

  					" for dest_node_acl->acl_group
  ");
  				atomic_dec(&dest_node_acl->acl_pr_ref_count);
  				smp_mb__after_atomic_dec();
  				core_scsi3_tpg_undepend_item(tmp_tpg);

  				cmd->scsi_sense_reason =
  					TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  				ret = -EINVAL;

  				goto out;
  			}
  
  			dest_tpg = tmp_tpg;

  			pr_debug("SPC-3 PR SPEC_I_PT: Located %s Node:"

  				" %s Port RTPI: %hu
  ",

  				dest_tpg->se_tpg_tfo->get_fabric_name(),

  				dest_node_acl->initiatorname, dest_rtpi);
  
  			spin_lock(&dev->se_port_lock);
  			break;
  		}
  		spin_unlock(&dev->se_port_lock);

  		if (!dest_tpg) {
  			pr_err("SPC-3 PR SPEC_I_PT: Unable to locate"

  					" dest_tpg
  ");

  			cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
  			ret = -EINVAL;

  			goto out;
  		}
  #if 0

  		pr_debug("SPC-3 PR SPEC_I_PT: Got %s data_length: %u tpdl: %u"

  			" tid_len: %d for %s + %s
  ",

  			dest_tpg->se_tpg_tfo->get_fabric_name(), cmd->data_length,

  			tpdl, tid_len, i_str, iport_ptr);
  #endif
  		if (tid_len > tpdl) {

  			pr_err("SPC-3 PR SPEC_I_PT: Illegal tid_len:"

  				" %u for Transport ID: %s
  ", tid_len, ptr);
  			core_scsi3_nodeacl_undepend_item(dest_node_acl);
  			core_scsi3_tpg_undepend_item(dest_tpg);

  			cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
  			ret = -EINVAL;

  			goto out;
  		}
  		/*
  		 * Locate the desintation struct se_dev_entry pointer for matching
  		 * RELATIVE TARGET PORT IDENTIFIER on the receiving I_T Nexus
  		 * Target Port.
  		 */
  		dest_se_deve = core_get_se_deve_from_rtpi(dest_node_acl,
  					dest_rtpi);

  		if (!dest_se_deve) {
  			pr_err("Unable to locate %s dest_se_deve"

  				" from destination RTPI: %hu
  ",

  				dest_tpg->se_tpg_tfo->get_fabric_name(),

  				dest_rtpi);
  
  			core_scsi3_nodeacl_undepend_item(dest_node_acl);
  			core_scsi3_tpg_undepend_item(dest_tpg);

  			cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
  			ret = -EINVAL;

  			goto out;
  		}
  
  		ret = core_scsi3_lunacl_depend_item(dest_se_deve);
  		if (ret < 0) {

  			pr_err("core_scsi3_lunacl_depend_item()"

  					" failed
  ");
  			atomic_dec(&dest_se_deve->pr_ref_count);
  			smp_mb__after_atomic_dec();
  			core_scsi3_nodeacl_undepend_item(dest_node_acl);
  			core_scsi3_tpg_undepend_item(dest_tpg);

  			cmd->scsi_sense_reason =
  				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  			ret = -EINVAL;

  			goto out;
  		}
  #if 0

  		pr_debug("SPC-3 PR SPEC_I_PT: Located %s Node: %s"

  			" dest_se_deve mapped_lun: %u
  ",

  			dest_tpg->se_tpg_tfo->get_fabric_name(),

  			dest_node_acl->initiatorname, dest_se_deve->mapped_lun);
  #endif
  		/*
  		 * Skip any TransportIDs that already have a registration for
  		 * this target port.
  		 */
  		pr_reg_e = __core_scsi3_locate_pr_reg(dev, dest_node_acl,
  					iport_ptr);
  		if (pr_reg_e) {
  			core_scsi3_put_pr_reg(pr_reg_e);
  			core_scsi3_lunacl_undepend_item(dest_se_deve);
  			core_scsi3_nodeacl_undepend_item(dest_node_acl);
  			core_scsi3_tpg_undepend_item(dest_tpg);
  			ptr += tid_len;
  			tpdl -= tid_len;
  			tid_len = 0;
  			continue;
  		}
  		/*
  		 * Allocate a struct pr_transport_id_holder and setup
  		 * the dest_node_acl and dest_se_deve pointers for the
  		 * loop below.
  		 */
  		tidh_new = kzalloc(sizeof(struct pr_transport_id_holder),
  				GFP_KERNEL);

  		if (!tidh_new) {
  			pr_err("Unable to allocate tidh_new
  ");

  			core_scsi3_lunacl_undepend_item(dest_se_deve);
  			core_scsi3_nodeacl_undepend_item(dest_node_acl);
  			core_scsi3_tpg_undepend_item(dest_tpg);

  			cmd->scsi_sense_reason =
  				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  			ret = -ENOMEM;

  			goto out;
  		}
  		INIT_LIST_HEAD(&tidh_new->dest_list);
  		tidh_new->dest_tpg = dest_tpg;
  		tidh_new->dest_node_acl = dest_node_acl;
  		tidh_new->dest_se_deve = dest_se_deve;
  
  		/*
  		 * Allocate, but do NOT add the registration for the
  		 * TransportID referenced SCSI Initiator port.  This
  		 * done because of the following from spc4r17 in section
  		 * 6.14.3 wrt SPEC_I_PT:
  		 *
  		 * "If a registration fails for any initiator port (e.g., if th
  		 * logical unit does not have enough resources available to
  		 * hold the registration information), no registrations shall be
  		 * made, and the command shall be terminated with
  		 * CHECK CONDITION status."
  		 *
  		 * That means we call __core_scsi3_alloc_registration() here,
  		 * and then call __core_scsi3_add_registration() in the
  		 * 2nd loop which will never fail.
  		 */

  		dest_pr_reg = __core_scsi3_alloc_registration(cmd->se_dev,

  				dest_node_acl, dest_se_deve, iport_ptr,
  				sa_res_key, all_tg_pt, aptpl);

  		if (!dest_pr_reg) {

  			core_scsi3_lunacl_undepend_item(dest_se_deve);
  			core_scsi3_nodeacl_undepend_item(dest_node_acl);
  			core_scsi3_tpg_undepend_item(dest_tpg);
  			kfree(tidh_new);

  			cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
  			ret = -EINVAL;

  			goto out;
  		}
  		tidh_new->dest_pr_reg = dest_pr_reg;
  		list_add_tail(&tidh_new->dest_list, &tid_dest_list);
  
  		ptr += tid_len;
  		tpdl -= tid_len;
  		tid_len = 0;
  
  	}

  
  	transport_kunmap_first_data_page(cmd);

  	/*
  	 * Go ahead and create a registrations from tid_dest_list for the
  	 * SPEC_I_PT provided TransportID for the *tidh referenced dest_node_acl
  	 * and dest_se_deve.
  	 *
  	 * The SA Reservation Key from the PROUT is set for the
  	 * registration, and ALL_TG_PT is also passed.  ALL_TG_PT=1
  	 * means that the TransportID Initiator port will be
  	 * registered on all of the target ports in the SCSI target device
  	 * ALL_TG_PT=0 means the registration will only be for the
  	 * SCSI target port the PROUT REGISTER with SPEC_I_PT=1
  	 * was received.
  	 */
  	list_for_each_entry_safe(tidh, tidh_tmp, &tid_dest_list, dest_list) {
  		dest_tpg = tidh->dest_tpg;
  		dest_node_acl = tidh->dest_node_acl;
  		dest_se_deve = tidh->dest_se_deve;
  		dest_pr_reg = tidh->dest_pr_reg;
  		dest_local_nexus = tidh->dest_local_nexus;
  
  		list_del(&tidh->dest_list);
  		kfree(tidh);
  
  		memset(i_buf, 0, PR_REG_ISID_ID_LEN);
  		prf_isid = core_pr_dump_initiator_port(dest_pr_reg, &i_buf[0],
  						PR_REG_ISID_ID_LEN);

  		__core_scsi3_add_registration(cmd->se_dev, dest_node_acl,

  					dest_pr_reg, 0, 0);

  		pr_debug("SPC-3 PR [%s] SPEC_I_PT: Successfully"

  			" registered Transport ID for Node: %s%s Mapped LUN:"

  			" %u
  ", dest_tpg->se_tpg_tfo->get_fabric_name(),

  			dest_node_acl->initiatorname, (prf_isid) ?
  			&i_buf[0] : "", dest_se_deve->mapped_lun);
  
  		if (dest_local_nexus)
  			continue;
  
  		core_scsi3_lunacl_undepend_item(dest_se_deve);
  		core_scsi3_nodeacl_undepend_item(dest_node_acl);
  		core_scsi3_tpg_undepend_item(dest_tpg);
  	}
  
  	return 0;
  out:

  	transport_kunmap_first_data_page(cmd);

  	/*
  	 * For the failure case, release everything from tid_dest_list
  	 * including *dest_pr_reg and the configfs dependances..
  	 */
  	list_for_each_entry_safe(tidh, tidh_tmp, &tid_dest_list, dest_list) {
  		dest_tpg = tidh->dest_tpg;
  		dest_node_acl = tidh->dest_node_acl;
  		dest_se_deve = tidh->dest_se_deve;
  		dest_pr_reg = tidh->dest_pr_reg;
  		dest_local_nexus = tidh->dest_local_nexus;
  
  		list_del(&tidh->dest_list);
  		kfree(tidh);
  		/*
  		 * Release any extra ALL_TG_PT=1 registrations for
  		 * the SPEC_I_PT=1 case.
  		 */
  		list_for_each_entry_safe(pr_reg_tmp, pr_reg_tmp_safe,
  				&dest_pr_reg->pr_reg_atp_list,
  				pr_reg_atp_mem_list) {
  			list_del(&pr_reg_tmp->pr_reg_atp_mem_list);
  			core_scsi3_lunacl_undepend_item(pr_reg_tmp->pr_reg_deve);
  			kmem_cache_free(t10_pr_reg_cache, pr_reg_tmp);
  		}
  
  		kfree(dest_pr_reg->pr_aptpl_buf);
  		kmem_cache_free(t10_pr_reg_cache, dest_pr_reg);
  
  		if (dest_local_nexus)
  			continue;
  
  		core_scsi3_lunacl_undepend_item(dest_se_deve);
  		core_scsi3_nodeacl_undepend_item(dest_node_acl);
  		core_scsi3_tpg_undepend_item(dest_tpg);
  	}
  	return ret;
  }
  
  /*
   * Called with struct se_device->dev_reservation_lock held
   */
  static int __core_scsi3_update_aptpl_buf(
  	struct se_device *dev,
  	unsigned char *buf,
  	u32 pr_aptpl_buf_len,
  	int clear_aptpl_metadata)
  {
  	struct se_lun *lun;
  	struct se_portal_group *tpg;

  	struct se_subsystem_dev *su_dev = dev->se_sub_dev;

  	struct t10_pr_registration *pr_reg;
  	unsigned char tmp[512], isid_buf[32];
  	ssize_t len = 0;
  	int reg_count = 0;
  
  	memset(buf, 0, pr_aptpl_buf_len);
  	/*
  	 * Called to clear metadata once APTPL has been deactivated.
  	 */
  	if (clear_aptpl_metadata) {
  		snprintf(buf, pr_aptpl_buf_len,
  				"No Registrations or Reservations
  ");
  		return 0;
  	}
  	/*
  	 * Walk the registration list..
  	 */

  	spin_lock(&su_dev->t10_pr.registration_lock);
  	list_for_each_entry(pr_reg, &su_dev->t10_pr.registration_list,

  			pr_reg_list) {
  
  		tmp[0] = '\0';
  		isid_buf[0] = '\0';
  		tpg = pr_reg->pr_reg_nacl->se_tpg;
  		lun = pr_reg->pr_reg_tg_pt_lun;
  		/*
  		 * Write out any ISID value to APTPL metadata that was included
  		 * in the original registration.
  		 */
  		if (pr_reg->isid_present_at_reg)
  			snprintf(isid_buf, 32, "initiator_sid=%s
  ",
  					pr_reg->pr_reg_isid);
  		/*
  		 * Include special metadata if the pr_reg matches the
  		 * reservation holder.
  		 */
  		if (dev->dev_pr_res_holder == pr_reg) {
  			snprintf(tmp, 512, "PR_REG_START: %d"
  				"
  initiator_fabric=%s
  "
  				"initiator_node=%s
  %s"
  				"sa_res_key=%llu
  "
  				"res_holder=1
  res_type=%02x
  "
  				"res_scope=%02x
  res_all_tg_pt=%d
  "
  				"mapped_lun=%u
  ", reg_count,

  				tpg->se_tpg_tfo->get_fabric_name(),

  				pr_reg->pr_reg_nacl->initiatorname, isid_buf,
  				pr_reg->pr_res_key, pr_reg->pr_res_type,
  				pr_reg->pr_res_scope, pr_reg->pr_reg_all_tg_pt,
  				pr_reg->pr_res_mapped_lun);
  		} else {
  			snprintf(tmp, 512, "PR_REG_START: %d
  "
  				"initiator_fabric=%s
  initiator_node=%s
  %s"
  				"sa_res_key=%llu
  res_holder=0
  "
  				"res_all_tg_pt=%d
  mapped_lun=%u
  ",

  				reg_count, tpg->se_tpg_tfo->get_fabric_name(),

  				pr_reg->pr_reg_nacl->initiatorname, isid_buf,
  				pr_reg->pr_res_key, pr_reg->pr_reg_all_tg_pt,
  				pr_reg->pr_res_mapped_lun);
  		}

  		if ((len + strlen(tmp) >= pr_aptpl_buf_len)) {

  			pr_err("Unable to update renaming"

  				" APTPL metadata
  ");

  			spin_unlock(&su_dev->t10_pr.registration_lock);
  			return -EMSGSIZE;

  		}
  		len += sprintf(buf+len, "%s", tmp);
  
  		/*
  		 * Include information about the associated SCSI target port.
  		 */
  		snprintf(tmp, 512, "target_fabric=%s
  target_node=%s
  "
  			"tpgt=%hu
  port_rtpi=%hu
  target_lun=%u
  PR_REG_END:"

  			" %d
  ", tpg->se_tpg_tfo->get_fabric_name(),
  			tpg->se_tpg_tfo->tpg_get_wwn(tpg),
  			tpg->se_tpg_tfo->tpg_get_tag(tpg),

  			lun->lun_sep->sep_rtpi, lun->unpacked_lun, reg_count);

  		if ((len + strlen(tmp) >= pr_aptpl_buf_len)) {

  			pr_err("Unable to update renaming"

  				" APTPL metadata
  ");

  			spin_unlock(&su_dev->t10_pr.registration_lock);
  			return -EMSGSIZE;

  		}
  		len += sprintf(buf+len, "%s", tmp);
  		reg_count++;
  	}

  	spin_unlock(&su_dev->t10_pr.registration_lock);

  	if (!reg_count)

  		len += sprintf(buf+len, "No Registrations or Reservations");
  
  	return 0;
  }
  
  static int core_scsi3_update_aptpl_buf(
  	struct se_device *dev,
  	unsigned char *buf,
  	u32 pr_aptpl_buf_len,
  	int clear_aptpl_metadata)
  {
  	int ret;
  
  	spin_lock(&dev->dev_reservation_lock);
  	ret = __core_scsi3_update_aptpl_buf(dev, buf, pr_aptpl_buf_len,
  				clear_aptpl_metadata);
  	spin_unlock(&dev->dev_reservation_lock);
  
  	return ret;
  }
  
  /*
   * Called with struct se_device->aptpl_file_mutex held
   */
  static int __core_scsi3_write_aptpl_to_file(
  	struct se_device *dev,
  	unsigned char *buf,
  	u32 pr_aptpl_buf_len)
  {

  	struct t10_wwn *wwn = &dev->se_sub_dev->t10_wwn;

  	struct file *file;
  	struct iovec iov[1];
  	mm_segment_t old_fs;
  	int flags = O_RDWR | O_CREAT | O_TRUNC;
  	char path[512];
  	int ret;
  
  	memset(iov, 0, sizeof(struct iovec));
  	memset(path, 0, 512);

  	if (strlen(&wwn->unit_serial[0]) >= 512) {

  		pr_err("WWN value for struct se_device does not fit"

  			" into path buffer
  ");

  		return -EMSGSIZE;

  	}
  
  	snprintf(path, 512, "/var/target/pr/aptpl_%s", &wwn->unit_serial[0]);
  	file = filp_open(path, flags, 0600);
  	if (IS_ERR(file) || !file || !file->f_dentry) {

  		pr_err("filp_open(%s) for APTPL metadata"

  			" failed
  ", path);

  		return (PTR_ERR(file) < 0 ? PTR_ERR(file) : -ENOENT);

  	}
  
  	iov[0].iov_base = &buf[0];

  	if (!pr_aptpl_buf_len)

  		iov[0].iov_len = (strlen(&buf[0]) + 1); /* Add extra for NULL */
  	else
  		iov[0].iov_len = pr_aptpl_buf_len;
  
  	old_fs = get_fs();
  	set_fs(get_ds());
  	ret = vfs_writev(file, &iov[0], 1, &file->f_pos);
  	set_fs(old_fs);
  
  	if (ret < 0) {

  		pr_debug("Error writing APTPL metadata file: %s
  ", path);

  		filp_close(file, NULL);

  		return -EIO;

  	}
  	filp_close(file, NULL);
  
  	return 0;
  }
  
  static int core_scsi3_update_and_write_aptpl(
  	struct se_device *dev,
  	unsigned char *in_buf,
  	u32 in_pr_aptpl_buf_len)
  {
  	unsigned char null_buf[64], *buf;
  	u32 pr_aptpl_buf_len;
  	int ret, clear_aptpl_metadata = 0;
  	/*
  	 * Can be called with a NULL pointer from PROUT service action CLEAR
  	 */

  	if (!in_buf) {

  		memset(null_buf, 0, 64);
  		buf = &null_buf[0];
  		/*
  		 * This will clear the APTPL metadata to:
  		 * "No Registrations or Reservations" status
  		 */
  		pr_aptpl_buf_len = 64;
  		clear_aptpl_metadata = 1;
  	} else {
  		buf = in_buf;
  		pr_aptpl_buf_len = in_pr_aptpl_buf_len;
  	}
  
  	ret = core_scsi3_update_aptpl_buf(dev, buf, pr_aptpl_buf_len,
  				clear_aptpl_metadata);
  	if (ret != 0)

  		return ret;

  	/*
  	 * __core_scsi3_write_aptpl_to_file() will call strlen()
  	 * on the passed buf to determine pr_aptpl_buf_len.
  	 */
  	ret = __core_scsi3_write_aptpl_to_file(dev, buf, 0);
  	if (ret != 0)

  		return ret;

  
  	return ret;
  }
  
  static int core_scsi3_emulate_pro_register(
  	struct se_cmd *cmd,
  	u64 res_key,
  	u64 sa_res_key,
  	int aptpl,
  	int all_tg_pt,
  	int spec_i_pt,
  	int ignore_key)
  {

  	struct se_session *se_sess = cmd->se_sess;

  	struct se_device *dev = cmd->se_dev;

  	struct se_dev_entry *se_deve;

  	struct se_lun *se_lun = cmd->se_lun;

  	struct se_portal_group *se_tpg;
  	struct t10_pr_registration *pr_reg, *pr_reg_p, *pr_reg_tmp, *pr_reg_e;

  	struct t10_reservation *pr_tmpl = &dev->se_sub_dev->t10_pr;

  	/* Used for APTPL metadata w/ UNREGISTER */
  	unsigned char *pr_aptpl_buf = NULL;
  	unsigned char isid_buf[PR_REG_ISID_LEN], *isid_ptr = NULL;
  	int pr_holder = 0, ret = 0, type;

  	if (!se_sess || !se_lun) {
  		pr_err("SPC-3 PR: se_sess || struct se_lun is NULL!
  ");

  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  		return -EINVAL;

  	}
  	se_tpg = se_sess->se_tpg;
  	se_deve = &se_sess->se_node_acl->device_list[cmd->orig_fe_lun];

  	if (se_tpg->se_tpg_tfo->sess_get_initiator_sid) {

  		memset(&isid_buf[0], 0, PR_REG_ISID_LEN);

  		se_tpg->se_tpg_tfo->sess_get_initiator_sid(se_sess, &isid_buf[0],

  				PR_REG_ISID_LEN);
  		isid_ptr = &isid_buf[0];
  	}
  	/*
  	 * Follow logic from spc4r17 Section 5.7.7, Register Behaviors Table 47
  	 */
  	pr_reg_e = core_scsi3_locate_pr_reg(dev, se_sess->se_node_acl, se_sess);

  	if (!pr_reg_e) {

  		if (res_key) {

  			pr_warn("SPC-3 PR: Reservation Key non-zero"

  				" for SA REGISTER, returning CONFLICT
  ");

  			cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  			return -EINVAL;

  		}
  		/*
  		 * Do nothing but return GOOD status.
  		 */

  		if (!sa_res_key)

  			return 0;

  		if (!spec_i_pt) {

  			/*
  			 * Perform the Service Action REGISTER on the Initiator
  			 * Port Endpoint that the PRO was received from on the
  			 * Logical Unit of the SCSI device server.
  			 */

  			ret = core_scsi3_alloc_registration(cmd->se_dev,

  					se_sess->se_node_acl, se_deve, isid_ptr,
  					sa_res_key, all_tg_pt, aptpl,
  					ignore_key, 0);
  			if (ret != 0) {

  				pr_err("Unable to allocate"

  					" struct t10_pr_registration
  ");

  				cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
  				return -EINVAL;

  			}
  		} else {
  			/*
  			 * Register both the Initiator port that received
  			 * PROUT SA REGISTER + SPEC_I_PT=1 and extract SCSI
  			 * TransportID from Parameter list and loop through
  			 * fabric dependent parameter list while calling
  			 * logic from of core_scsi3_alloc_registration() for
  			 * each TransportID provided SCSI Initiator Port/Device
  			 */
  			ret = core_scsi3_decode_spec_i_port(cmd, se_tpg,
  					isid_ptr, sa_res_key, all_tg_pt, aptpl);
  			if (ret != 0)
  				return ret;
  		}
  		/*
  		 * Nothing left to do for the APTPL=0 case.
  		 */

  		if (!aptpl) {

  			pr_tmpl->pr_aptpl_active = 0;

  			core_scsi3_update_and_write_aptpl(cmd->se_dev, NULL, 0);

  			pr_debug("SPC-3 PR: Set APTPL Bit Deactivated for"

  					" REGISTER
  ");
  			return 0;
  		}
  		/*
  		 * Locate the newly allocated local I_T Nexus *pr_reg, and
  		 * update the APTPL metadata information using its
  		 * preallocated *pr_reg->pr_aptpl_buf.
  		 */

  		pr_reg = core_scsi3_locate_pr_reg(cmd->se_dev,

  				se_sess->se_node_acl, se_sess);

  		ret = core_scsi3_update_and_write_aptpl(cmd->se_dev,

  				&pr_reg->pr_aptpl_buf[0],
  				pr_tmpl->pr_aptpl_buf_len);

  		if (!ret) {

  			pr_tmpl->pr_aptpl_active = 1;

  			pr_debug("SPC-3 PR: Set APTPL Bit Activated for REGISTER
  ");

  		}
  
  		core_scsi3_put_pr_reg(pr_reg);
  		return ret;
  	} else {
  		/*
  		 * Locate the existing *pr_reg via struct se_node_acl pointers
  		 */
  		pr_reg = pr_reg_e;
  		type = pr_reg->pr_res_type;

  		if (!ignore_key) {

  			if (res_key != pr_reg->pr_res_key) {

  				pr_err("SPC-3 PR REGISTER: Received"

  					" res_key: 0x%016Lx does not match"
  					" existing SA REGISTER res_key:"
  					" 0x%016Lx
  ", res_key,
  					pr_reg->pr_res_key);
  				core_scsi3_put_pr_reg(pr_reg);

  				cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  				return -EINVAL;

  			}
  		}
  		if (spec_i_pt) {

  			pr_err("SPC-3 PR UNREGISTER: SPEC_I_PT"

  				" set while sa_res_key=0
  ");
  			core_scsi3_put_pr_reg(pr_reg);

  			cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
  			return -EINVAL;

  		}
  		/*
  		 * An existing ALL_TG_PT=1 registration being released
  		 * must also set ALL_TG_PT=1 in the incoming PROUT.
  		 */
  		if (pr_reg->pr_reg_all_tg_pt && !(all_tg_pt)) {

  			pr_err("SPC-3 PR UNREGISTER: ALL_TG_PT=1"

  				" registration exists, but ALL_TG_PT=1 bit not"
  				" present in received PROUT
  ");
  			core_scsi3_put_pr_reg(pr_reg);

  			cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;
  			return -EINVAL;

  		}
  		/*
  		 * Allocate APTPL metadata buffer used for UNREGISTER ops
  		 */
  		if (aptpl) {
  			pr_aptpl_buf = kzalloc(pr_tmpl->pr_aptpl_buf_len,
  						GFP_KERNEL);

  			if (!pr_aptpl_buf) {
  				pr_err("Unable to allocate"

  					" pr_aptpl_buf
  ");
  				core_scsi3_put_pr_reg(pr_reg);

  				cmd->scsi_sense_reason =
  					TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  				return -EINVAL;

  			}
  		}
  		/*
  		 * sa_res_key=0 Unregister Reservation Key for registered I_T
  		 * Nexus sa_res_key=1 Change Reservation Key for registered I_T
  		 * Nexus.
  		 */

  		if (!sa_res_key) {

  			pr_holder = core_scsi3_check_implict_release(

  					cmd->se_dev, pr_reg);

  			if (pr_holder < 0) {
  				kfree(pr_aptpl_buf);
  				core_scsi3_put_pr_reg(pr_reg);

  				cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  				return -EINVAL;

  			}
  
  			spin_lock(&pr_tmpl->registration_lock);
  			/*
  			 * Release all ALL_TG_PT=1 for the matching SCSI Initiator Port
  			 * and matching pr_res_key.
  			 */
  			if (pr_reg->pr_reg_all_tg_pt) {
  				list_for_each_entry_safe(pr_reg_p, pr_reg_tmp,
  						&pr_tmpl->registration_list,
  						pr_reg_list) {

  					if (!pr_reg_p->pr_reg_all_tg_pt)

  						continue;
  
  					if (pr_reg_p->pr_res_key != res_key)
  						continue;
  
  					if (pr_reg == pr_reg_p)
  						continue;
  
  					if (strcmp(pr_reg->pr_reg_nacl->initiatorname,
  						   pr_reg_p->pr_reg_nacl->initiatorname))
  						continue;
  
  					__core_scsi3_free_registration(dev,
  							pr_reg_p, NULL, 0);
  				}
  			}
  			/*
  			 * Release the calling I_T Nexus registration now..
  			 */

  			__core_scsi3_free_registration(cmd->se_dev, pr_reg,

  							NULL, 1);
  			/*
  			 * From spc4r17, section 5.7.11.3 Unregistering
  			 *
  			 * If the persistent reservation is a registrants only
  			 * type, the device server shall establish a unit
  			 * attention condition for the initiator port associated
  			 * with every registered I_T nexus except for the I_T
  			 * nexus on which the PERSISTENT RESERVE OUT command was
  			 * received, with the additional sense code set to
  			 * RESERVATIONS RELEASED.
  			 */
  			if (pr_holder &&
  			   ((type == PR_TYPE_WRITE_EXCLUSIVE_REGONLY) ||
  			    (type == PR_TYPE_EXCLUSIVE_ACCESS_REGONLY))) {
  				list_for_each_entry(pr_reg_p,
  						&pr_tmpl->registration_list,
  						pr_reg_list) {
  
  					core_scsi3_ua_allocate(
  						pr_reg_p->pr_reg_nacl,
  						pr_reg_p->pr_res_mapped_lun,
  						0x2A,
  						ASCQ_2AH_RESERVATIONS_RELEASED);
  				}
  			}
  			spin_unlock(&pr_tmpl->registration_lock);

  			if (!aptpl) {

  				pr_tmpl->pr_aptpl_active = 0;
  				core_scsi3_update_and_write_aptpl(dev, NULL, 0);

  				pr_debug("SPC-3 PR: Set APTPL Bit Deactivated"

  						" for UNREGISTER
  ");
  				return 0;
  			}
  
  			ret = core_scsi3_update_and_write_aptpl(dev,
  					&pr_aptpl_buf[0],
  					pr_tmpl->pr_aptpl_buf_len);

  			if (!ret) {

  				pr_tmpl->pr_aptpl_active = 1;

  				pr_debug("SPC-3 PR: Set APTPL Bit Activated"

  						" for UNREGISTER
  ");
  			}
  
  			kfree(pr_aptpl_buf);
  			return ret;
  		} else {
  			/*
  			 * Increment PRgeneration counter for struct se_device"
  			 * upon a successful REGISTER, see spc4r17 section 6.3.2
  			 * READ_KEYS service action.
  			 */
  			pr_reg->pr_res_generation = core_scsi3_pr_generation(

  							cmd->se_dev);

  			pr_reg->pr_res_key = sa_res_key;

  			pr_debug("SPC-3 PR [%s] REGISTER%s: Changed Reservation"

  				" Key for %s to: 0x%016Lx PRgeneration:"

  				" 0x%08x
  ", cmd->se_tfo->get_fabric_name(),

  				(ignore_key) ? "_AND_IGNORE_EXISTING_KEY" : "",
  				pr_reg->pr_reg_nacl->initiatorname,
  				pr_reg->pr_res_key, pr_reg->pr_res_generation);

  			if (!aptpl) {

  				pr_tmpl->pr_aptpl_active = 0;
  				core_scsi3_update_and_write_aptpl(dev, NULL, 0);
  				core_scsi3_put_pr_reg(pr_reg);

  				pr_debug("SPC-3 PR: Set APTPL Bit Deactivated"

  						" for REGISTER
  ");
  				return 0;
  			}
  
  			ret = core_scsi3_update_and_write_aptpl(dev,
  					&pr_aptpl_buf[0],
  					pr_tmpl->pr_aptpl_buf_len);

  			if (!ret) {

  				pr_tmpl->pr_aptpl_active = 1;

  				pr_debug("SPC-3 PR: Set APTPL Bit Activated"

  						" for REGISTER
  ");
  			}
  
  			kfree(pr_aptpl_buf);
  			core_scsi3_put_pr_reg(pr_reg);
  		}
  	}
  	return 0;
  }
  
  unsigned char *core_scsi3_pr_dump_type(int type)
  {
  	switch (type) {
  	case PR_TYPE_WRITE_EXCLUSIVE:
  		return "Write Exclusive Access";
  	case PR_TYPE_EXCLUSIVE_ACCESS:
  		return "Exclusive Access";
  	case PR_TYPE_WRITE_EXCLUSIVE_REGONLY:
  		return "Write Exclusive Access, Registrants Only";
  	case PR_TYPE_EXCLUSIVE_ACCESS_REGONLY:
  		return "Exclusive Access, Registrants Only";
  	case PR_TYPE_WRITE_EXCLUSIVE_ALLREG:
  		return "Write Exclusive Access, All Registrants";
  	case PR_TYPE_EXCLUSIVE_ACCESS_ALLREG:
  		return "Exclusive Access, All Registrants";
  	default:
  		break;
  	}
  
  	return "Unknown SPC-3 PR Type";
  }
  
  static int core_scsi3_pro_reserve(
  	struct se_cmd *cmd,
  	struct se_device *dev,
  	int type,
  	int scope,
  	u64 res_key)
  {

  	struct se_session *se_sess = cmd->se_sess;

  	struct se_dev_entry *se_deve;

  	struct se_lun *se_lun = cmd->se_lun;

  	struct se_portal_group *se_tpg;
  	struct t10_pr_registration *pr_reg, *pr_res_holder;

  	struct t10_reservation *pr_tmpl = &dev->se_sub_dev->t10_pr;

  	char i_buf[PR_REG_ISID_ID_LEN];
  	int ret, prf_isid;
  
  	memset(i_buf, 0, PR_REG_ISID_ID_LEN);

  	if (!se_sess || !se_lun) {
  		pr_err("SPC-3 PR: se_sess || struct se_lun is NULL!
  ");

  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  		return -EINVAL;

  	}
  	se_tpg = se_sess->se_tpg;
  	se_deve = &se_sess->se_node_acl->device_list[cmd->orig_fe_lun];
  	/*
  	 * Locate the existing *pr_reg via struct se_node_acl pointers
  	 */

  	pr_reg = core_scsi3_locate_pr_reg(cmd->se_dev, se_sess->se_node_acl,

  				se_sess);

  	if (!pr_reg) {
  		pr_err("SPC-3 PR: Unable to locate"

  			" PR_REGISTERED *pr_reg for RESERVE
  ");

  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  		return -EINVAL;

  	}
  	/*
  	 * From spc4r17 Section 5.7.9: Reserving:
  	 *
  	 * An application client creates a persistent reservation by issuing
  	 * a PERSISTENT RESERVE OUT command with RESERVE service action through
  	 * a registered I_T nexus with the following parameters:
  	 *    a) RESERVATION KEY set to the value of the reservation key that is
  	 * 	 registered with the logical unit for the I_T nexus; and
  	 */
  	if (res_key != pr_reg->pr_res_key) {

  		pr_err("SPC-3 PR RESERVE: Received res_key: 0x%016Lx"

  			" does not match existing SA REGISTER res_key:"
  			" 0x%016Lx
  ", res_key, pr_reg->pr_res_key);
  		core_scsi3_put_pr_reg(pr_reg);

  		cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  		return -EINVAL;

  	}
  	/*
  	 * From spc4r17 Section 5.7.9: Reserving:
  	 *
  	 * From above:
  	 *  b) TYPE field and SCOPE field set to the persistent reservation
  	 *     being created.
  	 *
  	 * Only one persistent reservation is allowed at a time per logical unit
  	 * and that persistent reservation has a scope of LU_SCOPE.
  	 */
  	if (scope != PR_SCOPE_LU_SCOPE) {

  		pr_err("SPC-3 PR: Illegal SCOPE: 0x%02x
  ", scope);

  		core_scsi3_put_pr_reg(pr_reg);

  		cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
  		return -EINVAL;

  	}
  	/*
  	 * See if we have an existing PR reservation holder pointer at
  	 * struct se_device->dev_pr_res_holder in the form struct t10_pr_registration
  	 * *pr_res_holder.
  	 */
  	spin_lock(&dev->dev_reservation_lock);
  	pr_res_holder = dev->dev_pr_res_holder;
  	if ((pr_res_holder)) {
  		/*
  		 * From spc4r17 Section 5.7.9: Reserving:
  		 *
  		 * If the device server receives a PERSISTENT RESERVE OUT
  		 * command from an I_T nexus other than a persistent reservation
  		 * holder (see 5.7.10) that attempts to create a persistent
  		 * reservation when a persistent reservation already exists for
  		 * the logical unit, then the command shall be completed with
  		 * RESERVATION CONFLICT status.
  		 */
  		if (pr_res_holder != pr_reg) {
  			struct se_node_acl *pr_res_nacl = pr_res_holder->pr_reg_nacl;

  			pr_err("SPC-3 PR: Attempted RESERVE from"

  				" [%s]: %s while reservation already held by"
  				" [%s]: %s, returning RESERVATION_CONFLICT
  ",

  				cmd->se_tfo->get_fabric_name(),

  				se_sess->se_node_acl->initiatorname,

  				pr_res_nacl->se_tpg->se_tpg_tfo->get_fabric_name(),

  				pr_res_holder->pr_reg_nacl->initiatorname);
  
  			spin_unlock(&dev->dev_reservation_lock);
  			core_scsi3_put_pr_reg(pr_reg);

  			cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  			return -EINVAL;

  		}
  		/*
  		 * From spc4r17 Section 5.7.9: Reserving:
  		 *
  		 * If a persistent reservation holder attempts to modify the
  		 * type or scope of an existing persistent reservation, the
  		 * command shall be completed with RESERVATION CONFLICT status.
  		 */
  		if ((pr_res_holder->pr_res_type != type) ||
  		    (pr_res_holder->pr_res_scope != scope)) {
  			struct se_node_acl *pr_res_nacl = pr_res_holder->pr_reg_nacl;

  			pr_err("SPC-3 PR: Attempted RESERVE from"

  				" [%s]: %s trying to change TYPE and/or SCOPE,"
  				" while reservation already held by [%s]: %s,"
  				" returning RESERVATION_CONFLICT
  ",

  				cmd->se_tfo->get_fabric_name(),

  				se_sess->se_node_acl->initiatorname,

  				pr_res_nacl->se_tpg->se_tpg_tfo->get_fabric_name(),

  				pr_res_holder->pr_reg_nacl->initiatorname);
  
  			spin_unlock(&dev->dev_reservation_lock);
  			core_scsi3_put_pr_reg(pr_reg);

  			cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  			return -EINVAL;

  		}
  		/*
  		 * From spc4r17 Section 5.7.9: Reserving:
  		 *
  		 * If the device server receives a PERSISTENT RESERVE OUT
  		 * command with RESERVE service action where the TYPE field and
  		 * the SCOPE field contain the same values as the existing type
  		 * and scope from a persistent reservation holder, it shall not
  		 * make any change to the existing persistent reservation and
  		 * shall completethe command with GOOD status.
  		 */
  		spin_unlock(&dev->dev_reservation_lock);
  		core_scsi3_put_pr_reg(pr_reg);

  		return 0;

  	}
  	/*
  	 * Otherwise, our *pr_reg becomes the PR reservation holder for said
  	 * TYPE/SCOPE.  Also set the received scope and type in *pr_reg.
  	 */
  	pr_reg->pr_res_scope = scope;
  	pr_reg->pr_res_type = type;
  	pr_reg->pr_res_holder = 1;
  	dev->dev_pr_res_holder = pr_reg;
  	prf_isid = core_pr_dump_initiator_port(pr_reg, &i_buf[0],
  				PR_REG_ISID_ID_LEN);

  	pr_debug("SPC-3 PR [%s] Service Action: RESERVE created new"

  		" reservation holder TYPE: %s ALL_TG_PT: %d
  ",

  		cmd->se_tfo->get_fabric_name(), core_scsi3_pr_dump_type(type),

  		(pr_reg->pr_reg_all_tg_pt) ? 1 : 0);

  	pr_debug("SPC-3 PR [%s] RESERVE Node: %s%s
  ",

  			cmd->se_tfo->get_fabric_name(),

  			se_sess->se_node_acl->initiatorname,
  			(prf_isid) ? &i_buf[0] : "");
  	spin_unlock(&dev->dev_reservation_lock);
  
  	if (pr_tmpl->pr_aptpl_active) {

  		ret = core_scsi3_update_and_write_aptpl(cmd->se_dev,

  				&pr_reg->pr_aptpl_buf[0],
  				pr_tmpl->pr_aptpl_buf_len);

  		if (!ret)
  			pr_debug("SPC-3 PR: Updated APTPL metadata"

  					" for RESERVE
  ");
  	}
  
  	core_scsi3_put_pr_reg(pr_reg);
  	return 0;
  }
  
  static int core_scsi3_emulate_pro_reserve(
  	struct se_cmd *cmd,
  	int type,
  	int scope,
  	u64 res_key)
  {
  	struct se_device *dev = cmd->se_dev;
  	int ret = 0;
  
  	switch (type) {
  	case PR_TYPE_WRITE_EXCLUSIVE:
  	case PR_TYPE_EXCLUSIVE_ACCESS:
  	case PR_TYPE_WRITE_EXCLUSIVE_REGONLY:
  	case PR_TYPE_EXCLUSIVE_ACCESS_REGONLY:
  	case PR_TYPE_WRITE_EXCLUSIVE_ALLREG:
  	case PR_TYPE_EXCLUSIVE_ACCESS_ALLREG:
  		ret = core_scsi3_pro_reserve(cmd, dev, type, scope, res_key);
  		break;
  	default:

  		pr_err("SPC-3 PR: Unknown Service Action RESERVE Type:"

  			" 0x%02x
  ", type);

  		cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;
  		return -EINVAL;

  	}
  
  	return ret;
  }
  
  /*
   * Called with struct se_device->dev_reservation_lock held.
   */
  static void __core_scsi3_complete_pro_release(
  	struct se_device *dev,
  	struct se_node_acl *se_nacl,
  	struct t10_pr_registration *pr_reg,
  	int explict)
  {
  	struct target_core_fabric_ops *tfo = se_nacl->se_tpg->se_tpg_tfo;
  	char i_buf[PR_REG_ISID_ID_LEN];
  	int prf_isid;
  
  	memset(i_buf, 0, PR_REG_ISID_ID_LEN);
  	prf_isid = core_pr_dump_initiator_port(pr_reg, &i_buf[0],
  				PR_REG_ISID_ID_LEN);
  	/*
  	 * Go ahead and release the current PR reservation holder.
  	 */
  	dev->dev_pr_res_holder = NULL;

  	pr_debug("SPC-3 PR [%s] Service Action: %s RELEASE cleared"

  		" reservation holder TYPE: %s ALL_TG_PT: %d
  ",
  		tfo->get_fabric_name(), (explict) ? "explict" : "implict",
  		core_scsi3_pr_dump_type(pr_reg->pr_res_type),
  		(pr_reg->pr_reg_all_tg_pt) ? 1 : 0);

  	pr_debug("SPC-3 PR [%s] RELEASE Node: %s%s
  ",

  		tfo->get_fabric_name(), se_nacl->initiatorname,
  		(prf_isid) ? &i_buf[0] : "");
  	/*
  	 * Clear TYPE and SCOPE for the next PROUT Service Action: RESERVE
  	 */
  	pr_reg->pr_res_holder = pr_reg->pr_res_type = pr_reg->pr_res_scope = 0;
  }
  
  static int core_scsi3_emulate_pro_release(
  	struct se_cmd *cmd,
  	int type,
  	int scope,
  	u64 res_key)
  {
  	struct se_device *dev = cmd->se_dev;

  	struct se_session *se_sess = cmd->se_sess;
  	struct se_lun *se_lun = cmd->se_lun;

  	struct t10_pr_registration *pr_reg, *pr_reg_p, *pr_res_holder;

  	struct t10_reservation *pr_tmpl = &dev->se_sub_dev->t10_pr;

  	int ret, all_reg = 0;

  	if (!se_sess || !se_lun) {
  		pr_err("SPC-3 PR: se_sess || struct se_lun is NULL!
  ");

  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  		return -EINVAL;

  	}
  	/*
  	 * Locate the existing *pr_reg via struct se_node_acl pointers
  	 */
  	pr_reg = core_scsi3_locate_pr_reg(dev, se_sess->se_node_acl, se_sess);

  	if (!pr_reg) {
  		pr_err("SPC-3 PR: Unable to locate"

  			" PR_REGISTERED *pr_reg for RELEASE
  ");

  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  		return -EINVAL;

  	}
  	/*
  	 * From spc4r17 Section 5.7.11.2 Releasing:
  	 *
  	 * If there is no persistent reservation or in response to a persistent
  	 * reservation release request from a registered I_T nexus that is not a
  	 * persistent reservation holder (see 5.7.10), the device server shall
  	 * do the following:
  	 *
  	 *     a) Not release the persistent reservation, if any;
  	 *     b) Not remove any registrations; and
  	 *     c) Complete the command with GOOD status.
  	 */
  	spin_lock(&dev->dev_reservation_lock);
  	pr_res_holder = dev->dev_pr_res_holder;

  	if (!pr_res_holder) {

  		/*
  		 * No persistent reservation, return GOOD status.
  		 */
  		spin_unlock(&dev->dev_reservation_lock);
  		core_scsi3_put_pr_reg(pr_reg);

  		return 0;

  	}
  	if ((pr_res_holder->pr_res_type == PR_TYPE_WRITE_EXCLUSIVE_ALLREG) ||
  	    (pr_res_holder->pr_res_type == PR_TYPE_EXCLUSIVE_ACCESS_ALLREG))
  		all_reg = 1;
  
  	if ((all_reg == 0) && (pr_res_holder != pr_reg)) {
  		/*
  		 * Non 'All Registrants' PR Type cases..
  		 * Release request from a registered I_T nexus that is not a
  		 * persistent reservation holder. return GOOD status.
  		 */
  		spin_unlock(&dev->dev_reservation_lock);
  		core_scsi3_put_pr_reg(pr_reg);

  		return 0;

  	}
  	/*
  	 * From spc4r17 Section 5.7.11.2 Releasing:
  	 *
  	 * Only the persistent reservation holder (see 5.7.10) is allowed to
  	 * release a persistent reservation.
  	 *
  	 * An application client releases the persistent reservation by issuing
  	 * a PERSISTENT RESERVE OUT command with RELEASE service action through
  	 * an I_T nexus that is a persistent reservation holder with the
  	 * following parameters:
  	 *
  	 *     a) RESERVATION KEY field set to the value of the reservation key
  	 *	  that is registered with the logical unit for the I_T nexus;
  	 */
  	if (res_key != pr_reg->pr_res_key) {

  		pr_err("SPC-3 PR RELEASE: Received res_key: 0x%016Lx"

  			" does not match existing SA REGISTER res_key:"
  			" 0x%016Lx
  ", res_key, pr_reg->pr_res_key);
  		spin_unlock(&dev->dev_reservation_lock);
  		core_scsi3_put_pr_reg(pr_reg);

  		cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  		return -EINVAL;

  	}
  	/*
  	 * From spc4r17 Section 5.7.11.2 Releasing and above:
  	 *
  	 * b) TYPE field and SCOPE field set to match the persistent
  	 *    reservation being released.
  	 */
  	if ((pr_res_holder->pr_res_type != type) ||
  	    (pr_res_holder->pr_res_scope != scope)) {
  		struct se_node_acl *pr_res_nacl = pr_res_holder->pr_reg_nacl;

  		pr_err("SPC-3 PR RELEASE: Attempted to release"

  			" reservation from [%s]: %s with different TYPE "
  			"and/or SCOPE  while reservation already held by"
  			" [%s]: %s, returning RESERVATION_CONFLICT
  ",

  			cmd->se_tfo->get_fabric_name(),

  			se_sess->se_node_acl->initiatorname,

  			pr_res_nacl->se_tpg->se_tpg_tfo->get_fabric_name(),

  			pr_res_holder->pr_reg_nacl->initiatorname);
  
  		spin_unlock(&dev->dev_reservation_lock);
  		core_scsi3_put_pr_reg(pr_reg);

  		cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  		return -EINVAL;

  	}
  	/*
  	 * In response to a persistent reservation release request from the
  	 * persistent reservation holder the device server shall perform a
  	 * release by doing the following as an uninterrupted series of actions:
  	 * a) Release the persistent reservation;
  	 * b) Not remove any registration(s);
  	 * c) If the released persistent reservation is a registrants only type
  	 * or all registrants type persistent reservation,
  	 *    the device server shall establish a unit attention condition for
  	 *    the initiator port associated with every regis-
  	 *    tered I_T nexus other than I_T nexus on which the PERSISTENT
  	 *    RESERVE OUT command with RELEASE service action was received,
  	 *    with the additional sense code set to RESERVATIONS RELEASED; and
  	 * d) If the persistent reservation is of any other type, the device
  	 *    server shall not establish a unit attention condition.
  	 */
  	__core_scsi3_complete_pro_release(dev, se_sess->se_node_acl,
  			pr_reg, 1);
  
  	spin_unlock(&dev->dev_reservation_lock);
  
  	if ((type != PR_TYPE_WRITE_EXCLUSIVE_REGONLY) &&
  	    (type != PR_TYPE_EXCLUSIVE_ACCESS_REGONLY) &&
  	    (type != PR_TYPE_WRITE_EXCLUSIVE_ALLREG) &&
  	    (type != PR_TYPE_EXCLUSIVE_ACCESS_ALLREG)) {
  		/*
  		 * If no UNIT ATTENTION conditions will be established for
  		 * PR_TYPE_WRITE_EXCLUSIVE or PR_TYPE_EXCLUSIVE_ACCESS
  		 * go ahead and check for APTPL=1 update+write below
  		 */
  		goto write_aptpl;
  	}
  
  	spin_lock(&pr_tmpl->registration_lock);
  	list_for_each_entry(pr_reg_p, &pr_tmpl->registration_list,
  			pr_reg_list) {
  		/*
  		 * Do not establish a UNIT ATTENTION condition
  		 * for the calling I_T Nexus
  		 */
  		if (pr_reg_p == pr_reg)
  			continue;
  
  		core_scsi3_ua_allocate(pr_reg_p->pr_reg_nacl,
  				pr_reg_p->pr_res_mapped_lun,
  				0x2A, ASCQ_2AH_RESERVATIONS_RELEASED);
  	}
  	spin_unlock(&pr_tmpl->registration_lock);
  
  write_aptpl:
  	if (pr_tmpl->pr_aptpl_active) {

  		ret = core_scsi3_update_and_write_aptpl(cmd->se_dev,

  				&pr_reg->pr_aptpl_buf[0],
  				pr_tmpl->pr_aptpl_buf_len);

  		if (!ret)
  			pr_debug("SPC-3 PR: Updated APTPL metadata for RELEASE
  ");

  	}
  
  	core_scsi3_put_pr_reg(pr_reg);
  	return 0;
  }
  
  static int core_scsi3_emulate_pro_clear(
  	struct se_cmd *cmd,
  	u64 res_key)
  {
  	struct se_device *dev = cmd->se_dev;
  	struct se_node_acl *pr_reg_nacl;

  	struct se_session *se_sess = cmd->se_sess;
  	struct t10_reservation *pr_tmpl = &dev->se_sub_dev->t10_pr;

  	struct t10_pr_registration *pr_reg, *pr_reg_tmp, *pr_reg_n, *pr_res_holder;
  	u32 pr_res_mapped_lun = 0;
  	int calling_it_nexus = 0;
  	/*
  	 * Locate the existing *pr_reg via struct se_node_acl pointers
  	 */

  	pr_reg_n = core_scsi3_locate_pr_reg(cmd->se_dev,

  			se_sess->se_node_acl, se_sess);

  	if (!pr_reg_n) {
  		pr_err("SPC-3 PR: Unable to locate"

  			" PR_REGISTERED *pr_reg for CLEAR
  ");

  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  		return -EINVAL;

  	}
  	/*
  	 * From spc4r17 section 5.7.11.6, Clearing:
  	 *
  	 * Any application client may release the persistent reservation and
  	 * remove all registrations from a device server by issuing a
  	 * PERSISTENT RESERVE OUT command with CLEAR service action through a
  	 * registered I_T nexus with the following parameter:
  	 *
  	 *	a) RESERVATION KEY field set to the value of the reservation key
  	 * 	   that is registered with the logical unit for the I_T nexus.
  	 */
  	if (res_key != pr_reg_n->pr_res_key) {

  		pr_err("SPC-3 PR REGISTER: Received"

  			" res_key: 0x%016Lx does not match"
  			" existing SA REGISTER res_key:"
  			" 0x%016Lx
  ", res_key, pr_reg_n->pr_res_key);
  		core_scsi3_put_pr_reg(pr_reg_n);

  		cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  		return -EINVAL;

  	}
  	/*
  	 * a) Release the persistent reservation, if any;
  	 */
  	spin_lock(&dev->dev_reservation_lock);
  	pr_res_holder = dev->dev_pr_res_holder;
  	if (pr_res_holder) {
  		struct se_node_acl *pr_res_nacl = pr_res_holder->pr_reg_nacl;
  		__core_scsi3_complete_pro_release(dev, pr_res_nacl,
  			pr_res_holder, 0);
  	}
  	spin_unlock(&dev->dev_reservation_lock);
  	/*
  	 * b) Remove all registration(s) (see spc4r17 5.7.7);
  	 */
  	spin_lock(&pr_tmpl->registration_lock);
  	list_for_each_entry_safe(pr_reg, pr_reg_tmp,
  			&pr_tmpl->registration_list, pr_reg_list) {
  
  		calling_it_nexus = (pr_reg_n == pr_reg) ? 1 : 0;
  		pr_reg_nacl = pr_reg->pr_reg_nacl;
  		pr_res_mapped_lun = pr_reg->pr_res_mapped_lun;
  		__core_scsi3_free_registration(dev, pr_reg, NULL,
  					calling_it_nexus);
  		/*
  		 * e) Establish a unit attention condition for the initiator
  		 *    port associated with every registered I_T nexus other
  		 *    than the I_T nexus on which the PERSISTENT RESERVE OUT
  		 *    command with CLEAR service action was received, with the
  		 *    additional sense code set to RESERVATIONS PREEMPTED.
  		 */

  		if (!calling_it_nexus)

  			core_scsi3_ua_allocate(pr_reg_nacl, pr_res_mapped_lun,
  				0x2A, ASCQ_2AH_RESERVATIONS_PREEMPTED);
  	}
  	spin_unlock(&pr_tmpl->registration_lock);

  	pr_debug("SPC-3 PR [%s] Service Action: CLEAR complete
  ",

  		cmd->se_tfo->get_fabric_name());

  
  	if (pr_tmpl->pr_aptpl_active) {

  		core_scsi3_update_and_write_aptpl(cmd->se_dev, NULL, 0);

  		pr_debug("SPC-3 PR: Updated APTPL metadata"

  				" for CLEAR
  ");
  	}
  
  	core_scsi3_pr_generation(dev);
  	return 0;
  }
  
  /*
   * Called with struct se_device->dev_reservation_lock held.
   */
  static void __core_scsi3_complete_pro_preempt(
  	struct se_device *dev,
  	struct t10_pr_registration *pr_reg,
  	struct list_head *preempt_and_abort_list,
  	int type,
  	int scope,
  	int abort)
  {
  	struct se_node_acl *nacl = pr_reg->pr_reg_nacl;
  	struct target_core_fabric_ops *tfo = nacl->se_tpg->se_tpg_tfo;
  	char i_buf[PR_REG_ISID_ID_LEN];
  	int prf_isid;
  
  	memset(i_buf, 0, PR_REG_ISID_ID_LEN);
  	prf_isid = core_pr_dump_initiator_port(pr_reg, &i_buf[0],
  				PR_REG_ISID_ID_LEN);
  	/*
  	 * Do an implict RELEASE of the existing reservation.
  	 */
  	if (dev->dev_pr_res_holder)
  		__core_scsi3_complete_pro_release(dev, nacl,
  				dev->dev_pr_res_holder, 0);
  
  	dev->dev_pr_res_holder = pr_reg;
  	pr_reg->pr_res_holder = 1;
  	pr_reg->pr_res_type = type;
  	pr_reg->pr_res_scope = scope;

  	pr_debug("SPC-3 PR [%s] Service Action: PREEMPT%s created new"

  		" reservation holder TYPE: %s ALL_TG_PT: %d
  ",
  		tfo->get_fabric_name(), (abort) ? "_AND_ABORT" : "",
  		core_scsi3_pr_dump_type(type),
  		(pr_reg->pr_reg_all_tg_pt) ? 1 : 0);

  	pr_debug("SPC-3 PR [%s] PREEMPT%s from Node: %s%s
  ",

  		tfo->get_fabric_name(), (abort) ? "_AND_ABORT" : "",
  		nacl->initiatorname, (prf_isid) ? &i_buf[0] : "");
  	/*
  	 * For PREEMPT_AND_ABORT, add the preempting reservation's
  	 * struct t10_pr_registration to the list that will be compared
  	 * against received CDBs..
  	 */
  	if (preempt_and_abort_list)
  		list_add_tail(&pr_reg->pr_reg_abort_list,
  				preempt_and_abort_list);
  }
  
  static void core_scsi3_release_preempt_and_abort(
  	struct list_head *preempt_and_abort_list,
  	struct t10_pr_registration *pr_reg_holder)
  {
  	struct t10_pr_registration *pr_reg, *pr_reg_tmp;
  
  	list_for_each_entry_safe(pr_reg, pr_reg_tmp, preempt_and_abort_list,
  				pr_reg_abort_list) {
  
  		list_del(&pr_reg->pr_reg_abort_list);
  		if (pr_reg_holder == pr_reg)
  			continue;
  		if (pr_reg->pr_res_holder) {

  			pr_warn("pr_reg->pr_res_holder still set
  ");

  			continue;
  		}
  
  		pr_reg->pr_reg_deve = NULL;
  		pr_reg->pr_reg_nacl = NULL;
  		kfree(pr_reg->pr_aptpl_buf);
  		kmem_cache_free(t10_pr_reg_cache, pr_reg);
  	}
  }
  
  int core_scsi3_check_cdb_abort_and_preempt(
  	struct list_head *preempt_and_abort_list,
  	struct se_cmd *cmd)
  {
  	struct t10_pr_registration *pr_reg, *pr_reg_tmp;
  
  	list_for_each_entry_safe(pr_reg, pr_reg_tmp, preempt_and_abort_list,
  				pr_reg_abort_list) {
  		if (pr_reg->pr_res_key == cmd->pr_res_key)
  			return 0;
  	}
  
  	return 1;
  }
  
  static int core_scsi3_pro_preempt(
  	struct se_cmd *cmd,
  	int type,
  	int scope,
  	u64 res_key,
  	u64 sa_res_key,
  	int abort)
  {

  	struct se_device *dev = cmd->se_dev;

  	struct se_dev_entry *se_deve;
  	struct se_node_acl *pr_reg_nacl;

  	struct se_session *se_sess = cmd->se_sess;

  	struct list_head preempt_and_abort_list;
  	struct t10_pr_registration *pr_reg, *pr_reg_tmp, *pr_reg_n, *pr_res_holder;

  	struct t10_reservation *pr_tmpl = &dev->se_sub_dev->t10_pr;

  	u32 pr_res_mapped_lun = 0;
  	int all_reg = 0, calling_it_nexus = 0, released_regs = 0;
  	int prh_type = 0, prh_scope = 0, ret;

  	if (!se_sess) {
  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  		return -EINVAL;
  	}

  
  	se_deve = &se_sess->se_node_acl->device_list[cmd->orig_fe_lun];

  	pr_reg_n = core_scsi3_locate_pr_reg(cmd->se_dev, se_sess->se_node_acl,

  				se_sess);

  	if (!pr_reg_n) {
  		pr_err("SPC-3 PR: Unable to locate"

  			" PR_REGISTERED *pr_reg for PREEMPT%s
  ",
  			(abort) ? "_AND_ABORT" : "");

  		cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  		return -EINVAL;

  	}
  	if (pr_reg_n->pr_res_key != res_key) {
  		core_scsi3_put_pr_reg(pr_reg_n);

  		cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  		return -EINVAL;

  	}
  	if (scope != PR_SCOPE_LU_SCOPE) {

  		pr_err("SPC-3 PR: Illegal SCOPE: 0x%02x
  ", scope);

  		core_scsi3_put_pr_reg(pr_reg_n);

  		cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
  		return -EINVAL;

  	}
  	INIT_LIST_HEAD(&preempt_and_abort_list);
  
  	spin_lock(&dev->dev_reservation_lock);
  	pr_res_holder = dev->dev_pr_res_holder;
  	if (pr_res_holder &&
  	   ((pr_res_holder->pr_res_type == PR_TYPE_WRITE_EXCLUSIVE_ALLREG) ||
  	    (pr_res_holder->pr_res_type == PR_TYPE_EXCLUSIVE_ACCESS_ALLREG)))
  		all_reg = 1;

  	if (!all_reg && !sa_res_key) {

  		spin_unlock(&dev->dev_reservation_lock);
  		core_scsi3_put_pr_reg(pr_reg_n);

  		cmd->scsi_sense_reason = TCM_INVALID_PARAMETER_LIST;
  		return -EINVAL;

  	}
  	/*
  	 * From spc4r17, section 5.7.11.4.4 Removing Registrations:
  	 *
  	 * If the SERVICE ACTION RESERVATION KEY field does not identify a
  	 * persistent reservation holder or there is no persistent reservation
  	 * holder (i.e., there is no persistent reservation), then the device
  	 * server shall perform a preempt by doing the following in an
  	 * uninterrupted series of actions. (See below..)
  	 */

  	if (!pr_res_holder || (pr_res_holder->pr_res_key != sa_res_key)) {

  		/*
  		 * No existing or SA Reservation Key matching reservations..
  		 *
  		 * PROUT SA PREEMPT with All Registrant type reservations are
  		 * allowed to be processed without a matching SA Reservation Key
  		 */
  		spin_lock(&pr_tmpl->registration_lock);
  		list_for_each_entry_safe(pr_reg, pr_reg_tmp,
  				&pr_tmpl->registration_list, pr_reg_list) {
  			/*
  			 * Removing of registrations in non all registrants
  			 * type reservations without a matching SA reservation
  			 * key.
  			 *
  			 * a) Remove the registrations for all I_T nexuses
  			 *    specified by the SERVICE ACTION RESERVATION KEY
  			 *    field;
  			 * b) Ignore the contents of the SCOPE and TYPE fields;
  			 * c) Process tasks as defined in 5.7.1; and
  			 * d) Establish a unit attention condition for the
  			 *    initiator port associated with every I_T nexus
  			 *    that lost its registration other than the I_T
  			 *    nexus on which the PERSISTENT RESERVE OUT command
  			 *    was received, with the additional sense code set
  			 *    to REGISTRATIONS PREEMPTED.
  			 */

  			if (!all_reg) {

  				if (pr_reg->pr_res_key != sa_res_key)
  					continue;
  
  				calling_it_nexus = (pr_reg_n == pr_reg) ? 1 : 0;
  				pr_reg_nacl = pr_reg->pr_reg_nacl;
  				pr_res_mapped_lun = pr_reg->pr_res_mapped_lun;
  				__core_scsi3_free_registration(dev, pr_reg,
  					(abort) ? &preempt_and_abort_list :
  						NULL, calling_it_nexus);
  				released_regs++;
  			} else {
  				/*
  				 * Case for any existing all registrants type
  				 * reservation, follow logic in spc4r17 section
  				 * 5.7.11.4 Preempting, Table 52 and Figure 7.
  				 *
  				 * For a ZERO SA Reservation key, release
  				 * all other registrations and do an implict
  				 * release of active persistent reservation.
  				 *
  				 * For a non-ZERO SA Reservation key, only
  				 * release the matching reservation key from
  				 * registrations.
  				 */
  				if ((sa_res_key) &&
  				     (pr_reg->pr_res_key != sa_res_key))
  					continue;
  
  				calling_it_nexus = (pr_reg_n == pr_reg) ? 1 : 0;
  				if (calling_it_nexus)
  					continue;
  
  				pr_reg_nacl = pr_reg->pr_reg_nacl;
  				pr_res_mapped_lun = pr_reg->pr_res_mapped_lun;
  				__core_scsi3_free_registration(dev, pr_reg,
  					(abort) ? &preempt_and_abort_list :
  						NULL, 0);
  				released_regs++;
  			}

  			if (!calling_it_nexus)

  				core_scsi3_ua_allocate(pr_reg_nacl,
  					pr_res_mapped_lun, 0x2A,
  					ASCQ_2AH_RESERVATIONS_PREEMPTED);
  		}
  		spin_unlock(&pr_tmpl->registration_lock);
  		/*
  		 * If a PERSISTENT RESERVE OUT with a PREEMPT service action or
  		 * a PREEMPT AND ABORT service action sets the SERVICE ACTION
  		 * RESERVATION KEY field to a value that does not match any
  		 * registered reservation key, then the device server shall
  		 * complete the command with RESERVATION CONFLICT status.
  		 */

  		if (!released_regs) {

  			spin_unlock(&dev->dev_reservation_lock);
  			core_scsi3_put_pr_reg(pr_reg_n);

  			cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  			return -EINVAL;

  		}
  		/*
  		 * For an existing all registrants type reservation
  		 * with a zero SA rservation key, preempt the existing
  		 * reservation with the new PR type and scope.
  		 */
  		if (pr_res_holder && all_reg && !(sa_res_key)) {
  			__core_scsi3_complete_pro_preempt(dev, pr_reg_n,
  				(abort) ? &preempt_and_abort_list : NULL,
  				type, scope, abort);
  
  			if (abort)
  				core_scsi3_release_preempt_and_abort(
  					&preempt_and_abort_list, pr_reg_n);
  		}
  		spin_unlock(&dev->dev_reservation_lock);
  
  		if (pr_tmpl->pr_aptpl_active) {

  			ret = core_scsi3_update_and_write_aptpl(cmd->se_dev,

  					&pr_reg_n->pr_aptpl_buf[0],
  					pr_tmpl->pr_aptpl_buf_len);

  			if (!ret)
  				pr_debug("SPC-3 PR: Updated APTPL"

  					" metadata for  PREEMPT%s
  ", (abort) ?
  					"_AND_ABORT" : "");
  		}
  
  		core_scsi3_put_pr_reg(pr_reg_n);

  		core_scsi3_pr_generation(cmd->se_dev);

  		return 0;
  	}
  	/*
  	 * The PREEMPTing SA reservation key matches that of the
  	 * existing persistent reservation, first, we check if
  	 * we are preempting our own reservation.
  	 * From spc4r17, section 5.7.11.4.3 Preempting
  	 * persistent reservations and registration handling
  	 *
  	 * If an all registrants persistent reservation is not
  	 * present, it is not an error for the persistent
  	 * reservation holder to preempt itself (i.e., a
  	 * PERSISTENT RESERVE OUT with a PREEMPT service action
  	 * or a PREEMPT AND ABORT service action with the
  	 * SERVICE ACTION RESERVATION KEY value equal to the
  	 * persistent reservation holder's reservation key that
  	 * is received from the persistent reservation holder).
  	 * In that case, the device server shall establish the
  	 * new persistent reservation and maintain the
  	 * registration.
  	 */
  	prh_type = pr_res_holder->pr_res_type;
  	prh_scope = pr_res_holder->pr_res_scope;
  	/*
  	 * If the SERVICE ACTION RESERVATION KEY field identifies a
  	 * persistent reservation holder (see 5.7.10), the device
  	 * server shall perform a preempt by doing the following as
  	 * an uninterrupted series of actions:
  	 *
  	 * a) Release the persistent reservation for the holder
  	 *    identified by the SERVICE ACTION RESERVATION KEY field;
  	 */
  	if (pr_reg_n != pr_res_holder)
  		__core_scsi3_complete_pro_release(dev,
  				pr_res_holder->pr_reg_nacl,
  				dev->dev_pr_res_holder, 0);
  	/*
  	 * b) Remove the registrations for all I_T nexuses identified
  	 *    by the SERVICE ACTION RESERVATION KEY field, except the
  	 *    I_T nexus that is being used for the PERSISTENT RESERVE
  	 *    OUT command. If an all registrants persistent reservation
  	 *    is present and the SERVICE ACTION RESERVATION KEY field
  	 *    is set to zero, then all registrations shall be removed
  	 *    except for that of the I_T nexus that is being used for
  	 *    the PERSISTENT RESERVE OUT command;
  	 */
  	spin_lock(&pr_tmpl->registration_lock);
  	list_for_each_entry_safe(pr_reg, pr_reg_tmp,
  			&pr_tmpl->registration_list, pr_reg_list) {
  
  		calling_it_nexus = (pr_reg_n == pr_reg) ? 1 : 0;
  		if (calling_it_nexus)
  			continue;
  
  		if (pr_reg->pr_res_key != sa_res_key)
  			continue;
  
  		pr_reg_nacl = pr_reg->pr_reg_nacl;
  		pr_res_mapped_lun = pr_reg->pr_res_mapped_lun;
  		__core_scsi3_free_registration(dev, pr_reg,
  				(abort) ? &preempt_and_abort_list : NULL,
  				calling_it_nexus);
  		/*
  		 * e) Establish a unit attention condition for the initiator
  		 *    port associated with every I_T nexus that lost its
  		 *    persistent reservation and/or registration, with the
  		 *    additional sense code set to REGISTRATIONS PREEMPTED;
  		 */
  		core_scsi3_ua_allocate(pr_reg_nacl, pr_res_mapped_lun, 0x2A,
  				ASCQ_2AH_RESERVATIONS_PREEMPTED);
  	}
  	spin_unlock(&pr_tmpl->registration_lock);
  	/*
  	 * c) Establish a persistent reservation for the preempting
  	 *    I_T nexus using the contents of the SCOPE and TYPE fields;
  	 */
  	__core_scsi3_complete_pro_preempt(dev, pr_reg_n,
  			(abort) ? &preempt_and_abort_list : NULL,
  			type, scope, abort);
  	/*
  	 * d) Process tasks as defined in 5.7.1;
  	 * e) See above..
  	 * f) If the type or scope has changed, then for every I_T nexus
  	 *    whose reservation key was not removed, except for the I_T
  	 *    nexus on which the PERSISTENT RESERVE OUT command was
  	 *    received, the device server shall establish a unit
  	 *    attention condition for the initiator port associated with
  	 *    that I_T nexus, with the additional sense code set to
  	 *    RESERVATIONS RELEASED. If the type or scope have not
  	 *    changed, then no unit attention condition(s) shall be
  	 *    established for this reason.
  	 */
  	if ((prh_type != type) || (prh_scope != scope)) {
  		spin_lock(&pr_tmpl->registration_lock);
  		list_for_each_entry_safe(pr_reg, pr_reg_tmp,
  				&pr_tmpl->registration_list, pr_reg_list) {
  
  			calling_it_nexus = (pr_reg_n == pr_reg) ? 1 : 0;
  			if (calling_it_nexus)
  				continue;
  
  			core_scsi3_ua_allocate(pr_reg->pr_reg_nacl,
  					pr_reg->pr_res_mapped_lun, 0x2A,
  					ASCQ_2AH_RESERVATIONS_RELEASED);
  		}
  		spin_unlock(&pr_tmpl->registration_lock);
  	}
  	spin_unlock(&dev->dev_reservation_lock);
  	/*
  	 * Call LUN_RESET logic upon list of struct t10_pr_registration,
  	 * All received CDBs for the matching existing reservation and
  	 * registrations undergo ABORT_TASK logic.
  	 *
  	 * From there, core_scsi3_release_preempt_and_abort() will
  	 * release every registration in the list (which have already
  	 * been removed from the primary pr_reg list), except the
  	 * new persistent reservation holder, the calling Initiator Port.
  	 */
  	if (abort) {
  		core_tmr_lun_reset(dev, NULL, &preempt_and_abort_list, cmd);
  		core_scsi3_release_preempt_and_abort(&preempt_and_abort_list,
  						pr_reg_n);
  	}
  
  	if (pr_tmpl->pr_aptpl_active) {

  		ret = core_scsi3_update_and_write_aptpl(cmd->se_dev,

  				&pr_reg_n->pr_aptpl_buf[0],
  				pr_tmpl->pr_aptpl_buf_len);

  		if (!ret)
  			pr_debug("SPC-3 PR: Updated APTPL metadata for PREEMPT"

  				"%s
  ", (abort) ? "_AND_ABORT" : "");
  	}
  
  	core_scsi3_put_pr_reg(pr_reg_n);

  	core_scsi3_pr_generation(cmd->se_dev);

  	return 0;
  }
  
  static int core_scsi3_emulate_pro_preempt(
  	struct se_cmd *cmd,
  	int type,
  	int scope,
  	u64 res_key,
  	u64 sa_res_key,
  	int abort)
  {
  	int ret = 0;
  
  	switch (type) {
  	case PR_TYPE_WRITE_EXCLUSIVE:
  	case PR_TYPE_EXCLUSIVE_ACCESS:
  	case PR_TYPE_WRITE_EXCLUSIVE_REGONLY:
  	case PR_TYPE_EXCLUSIVE_ACCESS_REGONLY:
  	case PR_TYPE_WRITE_EXCLUSIVE_ALLREG:
  	case PR_TYPE_EXCLUSIVE_ACCESS_ALLREG:
  		ret = core_scsi3_pro_preempt(cmd, type, scope,
  				res_key, sa_res_key, abort);
  		break;
  	default:

  		pr_err("SPC-3 PR: Unknown Service Action PREEMPT%s"

  			" Type: 0x%02x
  ", (abort) ? "_AND_ABORT" : "", type);

  		cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;
  		return -EINVAL;

  	}
  
  	return ret;
  }
  
  
  static int core_scsi3_emulate_pro_register_and_move(
  	struct se_cmd *cmd,
  	u64 res_key,
  	u64 sa_res_key,
  	int aptpl,
  	int unreg)
  {

  	struct se_session *se_sess = cmd->se_sess;

  	struct se_device *dev = cmd->se_dev;

  	struct se_dev_entry *se_deve, *dest_se_deve = NULL;

  	struct se_lun *se_lun = cmd->se_lun;

  	struct se_node_acl *pr_res_nacl, *pr_reg_nacl, *dest_node_acl = NULL;
  	struct se_port *se_port;
  	struct se_portal_group *se_tpg, *dest_se_tpg = NULL;
  	struct target_core_fabric_ops *dest_tf_ops = NULL, *tf_ops;
  	struct t10_pr_registration *pr_reg, *pr_res_holder, *dest_pr_reg;

  	struct t10_reservation *pr_tmpl = &dev->se_sub_dev->t10_pr;

  	unsigned char *buf;

  	unsigned char *initiator_str;
  	char *iport_ptr = NULL, dest_iport[64], i_buf[PR_REG_ISID_ID_LEN];
  	u32 tid_len, tmp_tid_len;
  	int new_reg = 0, type, scope, ret, matching_iname, prf_isid;
  	unsigned short rtpi;
  	unsigned char proto_ident;

  	if (!se_sess || !se_lun) {
  		pr_err("SPC-3 PR: se_sess || struct se_lun is NULL!
  ");

  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  		return -EINVAL;

  	}
  	memset(dest_iport, 0, 64);
  	memset(i_buf, 0, PR_REG_ISID_ID_LEN);
  	se_tpg = se_sess->se_tpg;

  	tf_ops = se_tpg->se_tpg_tfo;

  	se_deve = &se_sess->se_node_acl->device_list[cmd->orig_fe_lun];
  	/*
  	 * Follow logic from spc4r17 Section 5.7.8, Table 50 --
  	 *	Register behaviors for a REGISTER AND MOVE service action
  	 *
  	 * Locate the existing *pr_reg via struct se_node_acl pointers
  	 */

  	pr_reg = core_scsi3_locate_pr_reg(cmd->se_dev, se_sess->se_node_acl,

  				se_sess);

  	if (!pr_reg) {
  		pr_err("SPC-3 PR: Unable to locate PR_REGISTERED"

  			" *pr_reg for REGISTER_AND_MOVE
  ");

  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  		return -EINVAL;

  	}
  	/*
  	 * The provided reservation key much match the existing reservation key
  	 * provided during this initiator's I_T nexus registration.
  	 */
  	if (res_key != pr_reg->pr_res_key) {

  		pr_warn("SPC-3 PR REGISTER_AND_MOVE: Received"

  			" res_key: 0x%016Lx does not match existing SA REGISTER"
  			" res_key: 0x%016Lx
  ", res_key, pr_reg->pr_res_key);
  		core_scsi3_put_pr_reg(pr_reg);

  		cmd->scsi_sense_reason = TCM_RESERVATION_CONFLICT;
  		return -EINVAL;

  	}
  	/*
  	 * The service active reservation key needs to be non zero
  	 */

  	if (!sa_res_key) {
  		pr_warn("SPC-3 PR REGISTER_AND_MOVE: Received zero"

  			" sa_res_key
  ");
  		core_scsi3_put_pr_reg(pr_reg);