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  • target_core_pr.c 125.56 KiB
    /*******************************************************************************
     * Filename:  target_core_pr.c
     *
     * This file contains SPC-3 compliant persistent reservations and
     * legacy SPC-2 reservations with compatible reservation handling (CRH=1)
     *
     * (c) Copyright 2009-2012 RisingTide Systems LLC.
     *
     * 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 <linux/file.h>
    #include <scsi/scsi.h>
    #include <scsi/scsi_cmnd.h>
    #include <asm/unaligned.h>
    
    #include <target/target_core_base.h>
    #include <target/target_core_backend.h>
    #include <target/target_core_fabric.h>
    #include <target/target_core_configfs.h>
    
    #include "target_core_internal.h"
    #include "target_core_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 sense_reason_t
    target_scsi2_reservation_check(struct se_cmd *cmd)
    {
    	struct se_device *dev = cmd->se_dev;
    	struct se_session *sess = cmd->se_sess;
    
    	switch (cmd->t_task_cdb[0]) {
    	case INQUIRY:
    	case RELEASE:
    	case RELEASE_10:
    		return 0;
    	default:
    		break;
    	}
    
    	if (!dev->dev_reserved_node_acl || !sess)
    		return 0;
    
    	if (dev->dev_reserved_node_acl != sess->se_node_acl)
    		return TCM_RESERVATION_CONFLICT;
    
    	if (dev->dev_reservation_flags & DRF_SPC2_RESERVATIONS_WITH_ISID) {
    		if (dev->dev_res_bin_isid != sess->sess_bin_isid)
    			return TCM_RESERVATION_CONFLICT;
    	}
    
    	return 0;
    }
    
    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)
    {
    	struct se_session *se_sess = cmd->se_sess;
    	struct se_device *dev = cmd->se_dev;
    	struct t10_pr_registration *pr_reg;
    	struct t10_reservation *pr_tmpl = &dev->t10_pr;
    	int conflict = 0;
    
    	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);
    			return 1;
    		}
    		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);
    			return 1;
    		}
    		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\n");
    		return -EBUSY;
    	}
    
    	return 0;
    }
    
    sense_reason_t
    target_scsi2_reservation_release(struct se_cmd *cmd)
    {
    	struct se_device *dev = cmd->se_dev;
    	struct se_session *sess = cmd->se_sess;
    	struct se_portal_group *tpg;
    	int rc;
    
    	if (!sess || !sess->se_tpg)
    		goto out;
    	rc = target_check_scsi2_reservation_conflict(cmd);
    	if (rc == 1)
    		goto out;
    	if (rc < 0)
    		return TCM_RESERVATION_CONFLICT;
    
    	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;
    
    	if (dev->dev_res_bin_isid != sess->sess_bin_isid)
    		goto out_unlock;
    
    	dev->dev_reserved_node_acl = NULL;
    	dev->dev_reservation_flags &= ~DRF_SPC2_RESERVATIONS;
    	if (dev->dev_reservation_flags & DRF_SPC2_RESERVATIONS_WITH_ISID) {
    		dev->dev_res_bin_isid = 0;
    		dev->dev_reservation_flags &= ~DRF_SPC2_RESERVATIONS_WITH_ISID;
    	}
    	tpg = sess->se_tpg;
    	pr_debug("SCSI-2 Released reservation for %s LUN: %u ->"
    		" MAPPED LUN: %u for %s\n", 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:
    	target_complete_cmd(cmd, GOOD);
    	return 0;
    }
    
    sense_reason_t
    target_scsi2_reservation_reserve(struct se_cmd *cmd)
    {
    	struct se_device *dev = cmd->se_dev;
    	struct se_session *sess = cmd->se_sess;
    	struct se_portal_group *tpg;
    	sense_reason_t ret = 0;
    	int rc;
    
    	if ((cmd->t_task_cdb[1] & 0x01) &&
    	    (cmd->t_task_cdb[1] & 0x02)) {
    		pr_err("LongIO and Obselete Bits set, returning"
    				" ILLEGAL_REQUEST\n");
    		return TCM_UNSUPPORTED_SCSI_OPCODE;
    	}
    	/*
    	 * This is currently the case for target_core_mod passthrough struct se_cmd
    	 * ops
    	 */
    	if (!sess || !sess->se_tpg)
    		goto out;
    	rc = target_check_scsi2_reservation_conflict(cmd);
    	if (rc == 1)
    		goto out;
    
    	if (rc < 0)
    		return TCM_RESERVATION_CONFLICT;
    
    	tpg = sess->se_tpg;
    	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\n",
    			tpg->se_tpg_tfo->get_fabric_name());
    		pr_err("Original reserver LUN: %u %s\n",
    			cmd->se_lun->unpacked_lun,
    			dev->dev_reserved_node_acl->initiatorname);
    		pr_err("Current attempt - LUN: %u -> MAPPED LUN: %u"
    			" from %s \n", cmd->se_lun->unpacked_lun,
    			cmd->se_deve->mapped_lun,
    			sess->se_node_acl->initiatorname);
    		ret = TCM_RESERVATION_CONFLICT;
    		goto out_unlock;
    	}
    
    	dev->dev_reserved_node_acl = sess->se_node_acl;
    	dev->dev_reservation_flags |= DRF_SPC2_RESERVATIONS;
    	if (sess->sess_bin_isid != 0) {
    		dev->dev_res_bin_isid = sess->sess_bin_isid;
    		dev->dev_reservation_flags |= DRF_SPC2_RESERVATIONS_WITH_ISID;
    	}
    	pr_debug("SCSI-2 Reserved %s LUN: %u -> MAPPED LUN: %u"
    		" for %s\n", 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)
    		target_complete_cmd(cmd, GOOD);
    	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,
    	u32 pr_reg_type)
    {
    	unsigned char *cdb = cmd->t_task_cdb;
    	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 */
    
    	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 target_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\n", 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\n",
    				(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:
    	case PERSISTENT_RESERVE_IN:
    		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) {
    		pr_debug("Allowing explict CDB: 0x%02x for %s"
    			" reservation holder\n", cdb[0],
    			core_scsi3_pr_dump_type(pr_reg_type));
    
    		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\n",
    				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 (!registered_nexus) {
    				pr_debug("Allowing implict CDB: 0x%02x"
    					" for %s reservation on unregistered"
    					" nexus\n", cdb[0],
    					core_scsi3_pr_dump_type(pr_reg_type));
    			}
    
    			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.
    			 */
    
    			pr_debug("Allowing implict CDB: 0x%02x for %s"
    				" reservation\n", cdb[0],
    				core_scsi3_pr_dump_type(pr_reg_type));
    
    			return 0;
    		}
    	}
    	pr_debug("%s Conflict for %sregistered nexus %s CDB: 0x%2x"
    		" for %s reservation\n", 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 sense_reason_t
    target_scsi3_pr_reservation_check(struct se_cmd *cmd)
    {
    	struct se_device *dev = cmd->se_dev;
    	struct se_session *sess = cmd->se_sess;
    	u32 pr_reg_type;
    
    	if (!dev->dev_pr_res_holder)
    		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)
    		goto check_nonholder;
    
    	if (dev->dev_pr_res_holder->isid_present_at_reg) {
    		if (dev->dev_pr_res_holder->pr_reg_bin_isid !=
    		    sess->sess_bin_isid) {
    			pr_reg_type |= 0x80000000;
    			goto check_nonholder;
    		}
    	}
    
    	return 0;
    
    check_nonholder:
    	if (core_scsi3_pr_seq_non_holder(cmd, pr_reg_type))
    		return TCM_RESERVATION_CONFLICT;
    	return 0;
    }
    
    static u32 core_scsi3_pr_generation(struct se_device *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 = dev->t10_pr.pr_generation++;
    	spin_unlock(&dev->dev_reservation_lock);
    
    	return prg;
    }
    
    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 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\n");
    		return NULL;
    	}
    
    	pr_reg->pr_aptpl_buf = kzalloc(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\n");
    		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\n");
    				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\n");
    		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\n");
    		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\n", (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\n",
    		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\n",
    		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->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_node_acl *nacl = lun_acl->se_lun_nacl;
    	struct se_dev_entry *deve = nacl->device_list[lun_acl->mapped_lun];
    
    	if (dev->dev_reservation_flags & DRF_SPC2_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\n", 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\n",
    		 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)\n",  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\n", 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 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->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) ?
    			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->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->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\n", 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->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\n",
    				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\n", 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)\n", 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\n", 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->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->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 sense_reason_t
    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;
    	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];
    	sense_reason_t ret;
    	u32 tpdl, tid_len = 0;
    	int dest_local_nexus, prf_isid;
    	u32 dest_rtpi = 0;
    
    	memset(dest_iport, 0, 64);
    
    	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\n");
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    	}
    	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);
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    	}
    	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);
    
    	if (cmd->data_length < 28) {
    		pr_warn("SPC-PR: Received PR OUT parameter list"
    			" length too small: %u\n", cmd->data_length);
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out;
    	}
    
    	buf = transport_kmap_data_sg(cmd);
    	if (!buf) {
    		ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    		goto out;
    	}
    
    	/*
    	 * 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\n", tpdl,
    			cmd->data_length);
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out_unmap;
    	}
    	/*
    	 * 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);
    
    			if (core_scsi3_tpg_depend_item(tmp_tpg)) {
    				pr_err(" core_scsi3_tpg_depend_item()"
    					" for tmp_tpg\n");
    				atomic_dec(&tmp_tpg->tpg_pr_ref_count);
    				smp_mb__after_atomic_dec();
    				ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    				goto out_unmap;
    			}
    			/*
    			 * Locate the destination 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;
    			}
    
    			if (core_scsi3_nodeacl_depend_item(dest_node_acl)) {
    				pr_err("configfs_depend_item() failed"
    					" for dest_node_acl->acl_group\n");
    				atomic_dec(&dest_node_acl->acl_pr_ref_count);
    				smp_mb__after_atomic_dec();
    				core_scsi3_tpg_undepend_item(tmp_tpg);
    				ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    				goto out_unmap;
    			}
    
    			dest_tpg = tmp_tpg;
    			pr_debug("SPC-3 PR SPEC_I_PT: Located %s Node:"
    				" %s Port RTPI: %hu\n",
    				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\n");
    			ret = TCM_INVALID_PARAMETER_LIST;
    			goto out_unmap;
    		}
    
    		pr_debug("SPC-3 PR SPEC_I_PT: Got %s data_length: %u tpdl: %u"
    			" tid_len: %d for %s + %s\n",
    			dest_tpg->se_tpg_tfo->get_fabric_name(), cmd->data_length,
    			tpdl, tid_len, i_str, iport_ptr);
    
    		if (tid_len > tpdl) {
    			pr_err("SPC-3 PR SPEC_I_PT: Illegal tid_len:"
    				" %u for Transport ID: %s\n", tid_len, ptr);
    			core_scsi3_nodeacl_undepend_item(dest_node_acl);
    			core_scsi3_tpg_undepend_item(dest_tpg);
    			ret = TCM_INVALID_PARAMETER_LIST;
    			goto out_unmap;
    		}
    		/*
    		 * 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\n",
    				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);
    			ret = TCM_INVALID_PARAMETER_LIST;
    			goto out_unmap;
    		}
    
    		if (core_scsi3_lunacl_depend_item(dest_se_deve)) {
    			pr_err("core_scsi3_lunacl_depend_item()"
    					" failed\n");
    			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);
    			ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    			goto out_unmap;
    		}
    
    		pr_debug("SPC-3 PR SPEC_I_PT: Located %s Node: %s"
    			" dest_se_deve mapped_lun: %u\n",
    			dest_tpg->se_tpg_tfo->get_fabric_name(),
    			dest_node_acl->initiatorname, dest_se_deve->mapped_lun);
    
    		/*
    		 * 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\n");
    			core_scsi3_lunacl_undepend_item(dest_se_deve);
    			core_scsi3_nodeacl_undepend_item(dest_node_acl);
    			core_scsi3_tpg_undepend_item(dest_tpg);
    			ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    			goto out_unmap;
    		}
    		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);
    			ret = TCM_INVALID_PARAMETER_LIST;
    			goto out_unmap;
    		}
    		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_data_sg(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\n", 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_unmap:
    	transport_kunmap_data_sg(cmd);
    out:
    	/*
    	 * 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 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\n");
    		return 0;
    	}
    	/*
    	 * Walk the registration list..
    	 */
    	spin_lock(&dev->t10_pr.registration_lock);
    	list_for_each_entry(pr_reg, &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\n",
    					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"
    				"\ninitiator_fabric=%s\n"
    				"initiator_node=%s\n%s"
    				"sa_res_key=%llu\n"
    				"res_holder=1\nres_type=%02x\n"
    				"res_scope=%02x\nres_all_tg_pt=%d\n"
    				"mapped_lun=%u\n", 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\n"
    				"initiator_fabric=%s\ninitiator_node=%s\n%s"
    				"sa_res_key=%llu\nres_holder=0\n"
    				"res_all_tg_pt=%d\nmapped_lun=%u\n",
    				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\n");
    			spin_unlock(&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\ntarget_node=%s\n"
    			"tpgt=%hu\nport_rtpi=%hu\ntarget_lun=%u\nPR_REG_END:"
    			" %d\n", 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\n");
    			spin_unlock(&dev->t10_pr.registration_lock);
    			return -EMSGSIZE;
    		}
    		len += sprintf(buf+len, "%s", tmp);
    		reg_count++;
    	}
    	spin_unlock(&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->t10_wwn;
    	struct file *file;
    	int flags = O_RDWR | O_CREAT | O_TRUNC;
    	char path[512];
    	int ret;
    
    	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\n");
    		return -EMSGSIZE;
    	}
    
    	snprintf(path, 512, "/var/target/pr/aptpl_%s", &wwn->unit_serial[0]);
    	file = filp_open(path, flags, 0600);
    	if (IS_ERR(file)) {
    		pr_err("filp_open(%s) for APTPL metadata"
    			" failed\n", path);
    		return PTR_ERR(file);
    	}
    
    	if (!pr_aptpl_buf_len)
    		pr_aptpl_buf_len = (strlen(&buf[0]) + 1); /* Add extra for NULL */
    
    	ret = kernel_write(file, buf, pr_aptpl_buf_len, 0);
    
    	if (ret < 0)
    		pr_debug("Error writing APTPL metadata file: %s\n", path);
    	fput(file);
    
    	return ret ? -EIO : 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 clear_aptpl_metadata = 0;
    	int ret;
    
    	/*
    	 * 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.
    	 */
    	return __core_scsi3_write_aptpl_to_file(dev, buf, 0);
    }
    
    static sense_reason_t
    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->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;
    	sense_reason_t ret = TCM_NO_SENSE;
    	int pr_holder = 0, type;
    
    	if (!se_sess || !se_lun) {
    		pr_err("SPC-3 PR: se_sess || struct se_lun is NULL!\n");
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    	}
    	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\n");
    			return TCM_RESERVATION_CONFLICT;
    		}
    		/*
    		 * 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.
    			 */
    			if (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)) {
    				pr_err("Unable to allocate"
    					" struct t10_pr_registration\n");
    				return TCM_INVALID_PARAMETER_LIST;
    			}
    		} 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\n");
    			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);
    
    		if (core_scsi3_update_and_write_aptpl(cmd->se_dev,
    				&pr_reg->pr_aptpl_buf[0],
    				pr_tmpl->pr_aptpl_buf_len)) {
    			pr_tmpl->pr_aptpl_active = 1;
    			pr_debug("SPC-3 PR: Set APTPL Bit Activated for REGISTER\n");
    		}
    
    		goto out_put_pr_reg;
    	}
    
    	/*
    	 * 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\n", res_key,
    				pr_reg->pr_res_key);
    			ret = TCM_RESERVATION_CONFLICT;
    			goto out_put_pr_reg;
    		}
    	}
    
    	if (spec_i_pt) {
    		pr_err("SPC-3 PR UNREGISTER: SPEC_I_PT"
    			" set while sa_res_key=0\n");
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out_put_pr_reg;
    	}
    
    	/*
    	 * 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\n");
    		ret = TCM_INVALID_CDB_FIELD;
    		goto out_put_pr_reg;
    	}
    
    	/*
    	 * 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\n");
    			ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    			goto out_put_pr_reg;
    		}
    	}
    
    	/*
    	 * 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);
    			ret = TCM_RESERVATION_CONFLICT;
    			goto out_put_pr_reg;
    		}
    
    		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\n");
    			return 0;
    		}
    
    		if (!core_scsi3_update_and_write_aptpl(dev, &pr_aptpl_buf[0],
    				pr_tmpl->pr_aptpl_buf_len)) {
    			pr_tmpl->pr_aptpl_active = 1;
    			pr_debug("SPC-3 PR: Set APTPL Bit Activated"
    					" for UNREGISTER\n");
    		}
    
    		goto out_free_aptpl_buf;
    	}
    
    	/*
    	 * 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\n", 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);
    		pr_debug("SPC-3 PR: Set APTPL Bit Deactivated"
    				" for REGISTER\n");
    		ret = 0;
    		goto out_put_pr_reg;
    	}
    
    	if (!core_scsi3_update_and_write_aptpl(dev, &pr_aptpl_buf[0],
    						pr_tmpl->pr_aptpl_buf_len)) {
    		pr_tmpl->pr_aptpl_active = 1;
    		pr_debug("SPC-3 PR: Set APTPL Bit Activated"
    			" for REGISTER\n");
    	}
    
    out_free_aptpl_buf:
    	kfree(pr_aptpl_buf);
    	ret = 0;
    out_put_pr_reg:
    	core_scsi3_put_pr_reg(pr_reg);
    	return ret;
    }
    
    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 sense_reason_t
    core_scsi3_pro_reserve(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_res_holder;
    	struct t10_reservation *pr_tmpl = &dev->t10_pr;
    	char i_buf[PR_REG_ISID_ID_LEN];
    	sense_reason_t ret;
    	int 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!\n");
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    	}
    	/*
    	 * 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\n");
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    	}
    	/*
    	 * 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\n", res_key, pr_reg->pr_res_key);
    		ret = TCM_RESERVATION_CONFLICT;
    		goto out_put_pr_reg;
    	}
    	/*
    	 * 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\n", scope);
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out_put_pr_reg;
    	}
    	/*
    	 * 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\n",
    				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);
    			ret = TCM_RESERVATION_CONFLICT;
    			goto out_put_pr_reg;
    		}
    		/*
    		 * 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\n",
    				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);
    			ret = TCM_RESERVATION_CONFLICT;
    			goto out_put_pr_reg;
    		}
    		/*
    		 * 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);
    		ret = 0;
    		goto out_put_pr_reg;
    	}
    	/*
    	 * 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\n",
    		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\n",
    			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) {
    		if (!core_scsi3_update_and_write_aptpl(cmd->se_dev,
    				&pr_reg->pr_aptpl_buf[0],
    				pr_tmpl->pr_aptpl_buf_len)) {
    			pr_debug("SPC-3 PR: Updated APTPL metadata"
    					" for RESERVE\n");
    		}
    	}
    
    	ret = 0;
    out_put_pr_reg:
    	core_scsi3_put_pr_reg(pr_reg);
    	return ret;
    }
    
    static sense_reason_t
    core_scsi3_emulate_pro_reserve(struct se_cmd *cmd, int type, int scope,
    		u64 res_key)
    {
    	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:
    		return core_scsi3_pro_reserve(cmd, type, scope, res_key);
    	default:
    		pr_err("SPC-3 PR: Unknown Service Action RESERVE Type:"
    			" 0x%02x\n", type);
    		return TCM_INVALID_CDB_FIELD;
    	}
    }
    
    /*
     * 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\n",
    		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\n",
    		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 sense_reason_t
    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->t10_pr;
    	int all_reg = 0;
    	sense_reason_t ret = 0;
    
    	if (!se_sess || !se_lun) {
    		pr_err("SPC-3 PR: se_sess || struct se_lun is NULL!\n");
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    	}
    	/*
    	 * 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\n");
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    	}
    	/*
    	 * 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);
    		goto out_put_pr_reg;
    	}
    	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);
    		goto out_put_pr_reg;
    	}
    
    	/*
    	 * 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\n", res_key, pr_reg->pr_res_key);
    		spin_unlock(&dev->dev_reservation_lock);
    		ret = TCM_RESERVATION_CONFLICT;
    		goto out_put_pr_reg;
    	}
    	/*
    	 * 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\n",
    			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);
    		ret = TCM_RESERVATION_CONFLICT;
    		goto out_put_pr_reg;
    	}
    	/*
    	 * 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) {
    		if (!core_scsi3_update_and_write_aptpl(cmd->se_dev,
    			&pr_reg->pr_aptpl_buf[0], pr_tmpl->pr_aptpl_buf_len)) {
    			pr_debug("SPC-3 PR: Updated APTPL metadata for RELEASE\n");
    		}
    	}
    out_put_pr_reg:
    	core_scsi3_put_pr_reg(pr_reg);
    	return ret;
    }
    
    static sense_reason_t
    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->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\n");
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    	}
    	/*
    	 * 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\n", res_key, pr_reg_n->pr_res_key);
    		core_scsi3_put_pr_reg(pr_reg_n);
    		return TCM_RESERVATION_CONFLICT;
    	}
    	/*
    	 * 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\n",
    		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\n");
    	}
    
    	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\n",
    		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\n",
    		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\n");
    			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);
    	}
    }
    
    static sense_reason_t
    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_node_acl *pr_reg_nacl;
    	struct se_session *se_sess = cmd->se_sess;
    	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->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;
    
    	if (!se_sess)
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    
    	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\n",
    			(abort) ? "_AND_ABORT" : "");
    		return TCM_RESERVATION_CONFLICT;
    	}
    	if (pr_reg_n->pr_res_key != res_key) {
    		core_scsi3_put_pr_reg(pr_reg_n);
    		return TCM_RESERVATION_CONFLICT;
    	}
    	if (scope != PR_SCOPE_LU_SCOPE) {
    		pr_err("SPC-3 PR: Illegal SCOPE: 0x%02x\n", scope);
    		core_scsi3_put_pr_reg(pr_reg_n);
    		return TCM_INVALID_PARAMETER_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);
    		return TCM_INVALID_PARAMETER_LIST;
    	}
    	/*
    	 * 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_REGISTRATIONS_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);
    			return TCM_RESERVATION_CONFLICT;
    		}
    		/*
    		 * 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) {
    			if (!core_scsi3_update_and_write_aptpl(cmd->se_dev,
    					&pr_reg_n->pr_aptpl_buf[0],
    					pr_tmpl->pr_aptpl_buf_len)) {
    				pr_debug("SPC-3 PR: Updated APTPL"
    					" metadata for  PREEMPT%s\n", (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_REGISTRATIONS_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) {
    		if (!core_scsi3_update_and_write_aptpl(cmd->se_dev,
    				&pr_reg_n->pr_aptpl_buf[0],
    				pr_tmpl->pr_aptpl_buf_len)) {
    			pr_debug("SPC-3 PR: Updated APTPL metadata for PREEMPT"
    				"%s\n", abort ? "_AND_ABORT" : "");
    		}
    	}
    
    	core_scsi3_put_pr_reg(pr_reg_n);
    	core_scsi3_pr_generation(cmd->se_dev);
    	return 0;
    }
    
    static sense_reason_t
    core_scsi3_emulate_pro_preempt(struct se_cmd *cmd, int type, int scope,
    		u64 res_key, u64 sa_res_key, int abort)
    {
    	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:
    		return core_scsi3_pro_preempt(cmd, type, scope, res_key,
    					      sa_res_key, abort);
    	default:
    		pr_err("SPC-3 PR: Unknown Service Action PREEMPT%s"
    			" Type: 0x%02x\n", (abort) ? "_AND_ABORT" : "", type);
    		return TCM_INVALID_CDB_FIELD;
    	}
    }
    
    
    static sense_reason_t
    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 *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->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, matching_iname, prf_isid;
    	sense_reason_t ret;
    	unsigned short rtpi;
    	unsigned char proto_ident;
    
    	if (!se_sess || !se_lun) {
    		pr_err("SPC-3 PR: se_sess || struct se_lun is NULL!\n");
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    	}
    
    	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;
    	/*
    	 * 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\n");
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    	}
    	/*
    	 * 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\n", res_key, pr_reg->pr_res_key);
    		ret = TCM_RESERVATION_CONFLICT;
    		goto out_put_pr_reg;
    	}
    	/*
    	 * 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\n");
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out_put_pr_reg;
    	}
    
    	/*
    	 * Determine the Relative Target Port Identifier where the reservation
    	 * will be moved to for the TransportID containing SCSI initiator WWN
    	 * information.
    	 */
    	buf = transport_kmap_data_sg(cmd);
    	if (!buf) {
    		ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    		goto out_put_pr_reg;
    	}
    
    	rtpi = (buf[18] & 0xff) << 8;
    	rtpi |= buf[19] & 0xff;
    	tid_len = (buf[20] & 0xff) << 24;
    	tid_len |= (buf[21] & 0xff) << 16;
    	tid_len |= (buf[22] & 0xff) << 8;
    	tid_len |= buf[23] & 0xff;
    	transport_kunmap_data_sg(cmd);
    	buf = NULL;
    
    	if ((tid_len + 24) != cmd->data_length) {
    		pr_err("SPC-3 PR: Illegal tid_len: %u + 24 byte header"
    			" does not equal CDB data_length: %u\n", tid_len,
    			cmd->data_length);
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out_put_pr_reg;
    	}
    
    	spin_lock(&dev->se_port_lock);
    	list_for_each_entry(se_port, &dev->dev_sep_list, sep_list) {
    		if (se_port->sep_rtpi != rtpi)
    			continue;
    		dest_se_tpg = se_port->sep_tpg;
    		if (!dest_se_tpg)
    			continue;
    		dest_tf_ops = dest_se_tpg->se_tpg_tfo;
    		if (!dest_tf_ops)
    			continue;
    
    		atomic_inc(&dest_se_tpg->tpg_pr_ref_count);
    		smp_mb__after_atomic_inc();
    		spin_unlock(&dev->se_port_lock);
    
    		if (core_scsi3_tpg_depend_item(dest_se_tpg)) {
    			pr_err("core_scsi3_tpg_depend_item() failed"
    				" for dest_se_tpg\n");
    			atomic_dec(&dest_se_tpg->tpg_pr_ref_count);
    			smp_mb__after_atomic_dec();
    			ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    			goto out_put_pr_reg;
    		}
    
    		spin_lock(&dev->se_port_lock);
    		break;
    	}
    	spin_unlock(&dev->se_port_lock);
    
    	if (!dest_se_tpg || !dest_tf_ops) {
    		pr_err("SPC-3 PR REGISTER_AND_MOVE: Unable to locate"
    			" fabric ops from Relative Target Port Identifier:"
    			" %hu\n", rtpi);
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out_put_pr_reg;
    	}
    
    	buf = transport_kmap_data_sg(cmd);
    	if (!buf) {
    		ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    		goto out_put_pr_reg;
    	}
    	proto_ident = (buf[24] & 0x0f);
    
    	pr_debug("SPC-3 PR REGISTER_AND_MOVE: Extracted Protocol Identifier:"
    			" 0x%02x\n", proto_ident);
    
    	if (proto_ident != dest_tf_ops->get_fabric_proto_ident(dest_se_tpg)) {
    		pr_err("SPC-3 PR REGISTER_AND_MOVE: Received"
    			" proto_ident: 0x%02x does not match ident: 0x%02x"
    			" from fabric: %s\n", proto_ident,
    			dest_tf_ops->get_fabric_proto_ident(dest_se_tpg),
    			dest_tf_ops->get_fabric_name());
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out;
    	}
    	if (dest_tf_ops->tpg_parse_pr_out_transport_id == NULL) {
    		pr_err("SPC-3 PR REGISTER_AND_MOVE: Fabric does not"
    			" containg a valid tpg_parse_pr_out_transport_id"
    			" function pointer\n");
    		ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    		goto out;
    	}
    	initiator_str = dest_tf_ops->tpg_parse_pr_out_transport_id(dest_se_tpg,
    			(const char *)&buf[24], &tmp_tid_len, &iport_ptr);
    	if (!initiator_str) {
    		pr_err("SPC-3 PR REGISTER_AND_MOVE: Unable to locate"
    			" initiator_str from Transport ID\n");
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out;
    	}
    
    	transport_kunmap_data_sg(cmd);
    	buf = NULL;
    
    	pr_debug("SPC-3 PR [%s] Extracted initiator %s identifier: %s"
    		" %s\n", dest_tf_ops->get_fabric_name(), (iport_ptr != NULL) ?
    		"port" : "device", initiator_str, (iport_ptr != NULL) ?
    		iport_ptr : "");
    	/*
    	 * If a PERSISTENT RESERVE OUT command with a REGISTER AND MOVE service
    	 * action specifies a TransportID that is the same as the initiator port
    	 * of the I_T nexus for the command received, then the command shall
    	 * be terminated with CHECK CONDITION status, with the sense key set to
    	 * ILLEGAL REQUEST, and the additional sense code set to INVALID FIELD
    	 * IN PARAMETER LIST.
    	 */
    	pr_reg_nacl = pr_reg->pr_reg_nacl;
    	matching_iname = (!strcmp(initiator_str,
    				  pr_reg_nacl->initiatorname)) ? 1 : 0;
    	if (!matching_iname)
    		goto after_iport_check;
    
    	if (!iport_ptr || !pr_reg->isid_present_at_reg) {
    		pr_err("SPC-3 PR REGISTER_AND_MOVE: TransportID: %s"
    			" matches: %s on received I_T Nexus\n", initiator_str,
    			pr_reg_nacl->initiatorname);
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out;
    	}
    	if (!strcmp(iport_ptr, pr_reg->pr_reg_isid)) {
    		pr_err("SPC-3 PR REGISTER_AND_MOVE: TransportID: %s %s"
    			" matches: %s %s on received I_T Nexus\n",
    			initiator_str, iport_ptr, pr_reg_nacl->initiatorname,
    			pr_reg->pr_reg_isid);
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out;
    	}
    after_iport_check:
    	/*
    	 * Locate the destination struct se_node_acl from the received Transport ID
    	 */
    	spin_lock_irq(&dest_se_tpg->acl_node_lock);
    	dest_node_acl = __core_tpg_get_initiator_node_acl(dest_se_tpg,
    				initiator_str);
    	if (dest_node_acl) {
    		atomic_inc(&dest_node_acl->acl_pr_ref_count);
    		smp_mb__after_atomic_inc();
    	}
    	spin_unlock_irq(&dest_se_tpg->acl_node_lock);
    
    	if (!dest_node_acl) {
    		pr_err("Unable to locate %s dest_node_acl for"
    			" TransportID%s\n", dest_tf_ops->get_fabric_name(),
    			initiator_str);
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out;
    	}
    
    	if (core_scsi3_nodeacl_depend_item(dest_node_acl)) {
    		pr_err("core_scsi3_nodeacl_depend_item() for"
    			" dest_node_acl\n");
    		atomic_dec(&dest_node_acl->acl_pr_ref_count);
    		smp_mb__after_atomic_dec();
    		dest_node_acl = NULL;
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out;
    	}
    
    	pr_debug("SPC-3 PR REGISTER_AND_MOVE: Found %s dest_node_acl:"
    		" %s from TransportID\n", dest_tf_ops->get_fabric_name(),
    		dest_node_acl->initiatorname);
    
    	/*
    	 * Locate the struct se_dev_entry pointer for the matching RELATIVE TARGET
    	 * PORT IDENTIFIER.
    	 */
    	dest_se_deve = core_get_se_deve_from_rtpi(dest_node_acl, rtpi);
    	if (!dest_se_deve) {
    		pr_err("Unable to locate %s dest_se_deve from RTPI:"
    			" %hu\n",  dest_tf_ops->get_fabric_name(), rtpi);
    		ret = TCM_INVALID_PARAMETER_LIST;
    		goto out;
    	}
    
    	if (core_scsi3_lunacl_depend_item(dest_se_deve)) {
    		pr_err("core_scsi3_lunacl_depend_item() failed\n");
    		atomic_dec(&dest_se_deve->pr_ref_count);
    		smp_mb__after_atomic_dec();
    		dest_se_deve = NULL;
    		ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    		goto out;
    	}
    
    	pr_debug("SPC-3 PR REGISTER_AND_MOVE: Located %s node %s LUN"
    		" ACL for dest_se_deve->mapped_lun: %u\n",
    		dest_tf_ops->get_fabric_name(), dest_node_acl->initiatorname,
    		dest_se_deve->mapped_lun);
    
    	/*
    	 * A persistent reservation needs to already existing in order to
    	 * successfully complete the REGISTER_AND_MOVE service action..
    	 */
    	spin_lock(&dev->dev_reservation_lock);
    	pr_res_holder = dev->dev_pr_res_holder;
    	if (!pr_res_holder) {
    		pr_warn("SPC-3 PR REGISTER_AND_MOVE: No reservation"
    			" currently held\n");
    		spin_unlock(&dev->dev_reservation_lock);
    		ret = TCM_INVALID_CDB_FIELD;
    		goto out;
    	}
    	/*
    	 * The received on I_T Nexus must be the reservation holder.
    	 *
    	 * From spc4r17 section 5.7.8  Table 50 --
    	 * 	Register behaviors for a REGISTER AND MOVE service action
    	 */
    	if (pr_res_holder != pr_reg) {
    		pr_warn("SPC-3 PR REGISTER_AND_MOVE: Calling I_T"
    			" Nexus is not reservation holder\n");
    		spin_unlock(&dev->dev_reservation_lock);
    		ret = TCM_RESERVATION_CONFLICT;
    		goto out;
    	}
    	/*
    	 * From spc4r17 section 5.7.8: registering and moving reservation
    	 *
    	 * If a PERSISTENT RESERVE OUT command with a REGISTER AND MOVE service
    	 * action is received and the established persistent reservation is a
    	 * Write Exclusive - All Registrants type or Exclusive Access -
    	 * All Registrants type reservation, then the command shall be completed
    	 * with RESERVATION CONFLICT status.
    	 */
    	if ((pr_res_holder->pr_res_type == PR_TYPE_WRITE_EXCLUSIVE_ALLREG) ||
    	    (pr_res_holder->pr_res_type == PR_TYPE_EXCLUSIVE_ACCESS_ALLREG)) {
    		pr_warn("SPC-3 PR REGISTER_AND_MOVE: Unable to move"
    			" reservation for type: %s\n",
    			core_scsi3_pr_dump_type(pr_res_holder->pr_res_type));
    		spin_unlock(&dev->dev_reservation_lock);
    		ret = TCM_RESERVATION_CONFLICT;
    		goto out;
    	}
    	pr_res_nacl = pr_res_holder->pr_reg_nacl;
    	/*
    	 * b) Ignore the contents of the (received) SCOPE and TYPE fields;
    	 */
    	type = pr_res_holder->pr_res_type;
    	scope = pr_res_holder->pr_res_type;
    	/*
    	 * c) Associate the reservation key specified in the SERVICE ACTION
    	 *    RESERVATION KEY field with the I_T nexus specified as the
    	 *    destination of the register and move, where:
    	 *    A) The I_T nexus is specified by the TransportID and the
    	 *	 RELATIVE TARGET PORT IDENTIFIER field (see 6.14.4); and
    	 *    B) Regardless of the TransportID format used, the association for
    	 *       the initiator port is based on either the initiator port name
    	 *       (see 3.1.71) on SCSI transport protocols where port names are
    	 *       required or the initiator port identifier (see 3.1.70) on SCSI
    	 *       transport protocols where port names are not required;
    	 * d) Register the reservation key specified in the SERVICE ACTION
    	 *    RESERVATION KEY field;
    	 * e) Retain the reservation key specified in the SERVICE ACTION
    	 *    RESERVATION KEY field and associated information;
    	 *
    	 * Also, It is not an error for a REGISTER AND MOVE service action to
    	 * register an I_T nexus that is already registered with the same
    	 * reservation key or a different reservation key.
    	 */
    	dest_pr_reg = __core_scsi3_locate_pr_reg(dev, dest_node_acl,
    					iport_ptr);
    	if (!dest_pr_reg) {
    		if (core_scsi3_alloc_registration(cmd->se_dev,
    				dest_node_acl, dest_se_deve, iport_ptr,
    				sa_res_key, 0, aptpl, 2, 1)) {
    			spin_unlock(&dev->dev_reservation_lock);
    			ret = TCM_INVALID_PARAMETER_LIST;
    			goto out;
    		}
    		dest_pr_reg = __core_scsi3_locate_pr_reg(dev, dest_node_acl,
    						iport_ptr);
    		new_reg = 1;
    	}
    	/*
    	 * f) Release the persistent reservation for the persistent reservation
    	 *    holder (i.e., the I_T nexus on which the
    	 */
    	__core_scsi3_complete_pro_release(dev, pr_res_nacl,
    			dev->dev_pr_res_holder, 0);
    	/*
    	 * g) Move the persistent reservation to the specified I_T nexus using
    	 *    the same scope and type as the persistent reservation released in
    	 *    item f); and
    	 */
    	dev->dev_pr_res_holder = dest_pr_reg;
    	dest_pr_reg->pr_res_holder = 1;
    	dest_pr_reg->pr_res_type = type;
    	pr_reg->pr_res_scope = scope;
    	prf_isid = core_pr_dump_initiator_port(pr_reg, &i_buf[0],
    				PR_REG_ISID_ID_LEN);
    	/*
    	 * Increment PRGeneration for existing registrations..
    	 */
    	if (!new_reg)
    		dest_pr_reg->pr_res_generation = pr_tmpl->pr_generation++;
    	spin_unlock(&dev->dev_reservation_lock);
    
    	pr_debug("SPC-3 PR [%s] Service Action: REGISTER_AND_MOVE"
    		" created new reservation holder TYPE: %s on object RTPI:"
    		" %hu  PRGeneration: 0x%08x\n", dest_tf_ops->get_fabric_name(),
    		core_scsi3_pr_dump_type(type), rtpi,
    		dest_pr_reg->pr_res_generation);
    	pr_debug("SPC-3 PR Successfully moved reservation from"
    		" %s Fabric Node: %s%s -> %s Fabric Node: %s %s\n",
    		tf_ops->get_fabric_name(), pr_reg_nacl->initiatorname,
    		(prf_isid) ? &i_buf[0] : "", dest_tf_ops->get_fabric_name(),
    		dest_node_acl->initiatorname, (iport_ptr != NULL) ?
    		iport_ptr : "");
    	/*
    	 * It is now safe to release configfs group dependencies for destination
    	 * of Transport ID Initiator Device/Port Identifier
    	 */
    	core_scsi3_lunacl_undepend_item(dest_se_deve);
    	core_scsi3_nodeacl_undepend_item(dest_node_acl);
    	core_scsi3_tpg_undepend_item(dest_se_tpg);
    	/*
    	 * h) If the UNREG bit is set to one, unregister (see 5.7.11.3) the I_T
    	 * nexus on which PERSISTENT RESERVE OUT command was received.
    	 */
    	if (unreg) {
    		spin_lock(&pr_tmpl->registration_lock);
    		__core_scsi3_free_registration(dev, pr_reg, NULL, 1);
    		spin_unlock(&pr_tmpl->registration_lock);
    	} else
    		core_scsi3_put_pr_reg(pr_reg);
    
    	/*
    	 * Clear the APTPL metadata if APTPL has been disabled, otherwise
    	 * write out the updated metadata to struct file for this SCSI device.
    	 */
    	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_AND_MOVE\n");
    	} else {
    		pr_tmpl->pr_aptpl_active = 1;
    		if (!core_scsi3_update_and_write_aptpl(cmd->se_dev,
    				&dest_pr_reg->pr_aptpl_buf[0],
    				pr_tmpl->pr_aptpl_buf_len)) {
    			pr_debug("SPC-3 PR: Set APTPL Bit Activated for"
    					" REGISTER_AND_MOVE\n");
    		}
    	}
    
    	transport_kunmap_data_sg(cmd);
    
    	core_scsi3_put_pr_reg(dest_pr_reg);
    	return 0;
    out:
    	if (buf)
    		transport_kunmap_data_sg(cmd);
    	if (dest_se_deve)
    		core_scsi3_lunacl_undepend_item(dest_se_deve);
    	if (dest_node_acl)
    		core_scsi3_nodeacl_undepend_item(dest_node_acl);
    	core_scsi3_tpg_undepend_item(dest_se_tpg);
    
    out_put_pr_reg:
    	core_scsi3_put_pr_reg(pr_reg);
    	return ret;
    }
    
    static unsigned long long core_scsi3_extract_reservation_key(unsigned char *cdb)
    {
    	unsigned int __v1, __v2;
    
    	__v1 = (cdb[0] << 24) | (cdb[1] << 16) | (cdb[2] << 8) | cdb[3];
    	__v2 = (cdb[4] << 24) | (cdb[5] << 16) | (cdb[6] << 8) | cdb[7];
    
    	return ((unsigned long long)__v2) | (unsigned long long)__v1 << 32;
    }
    
    /*
     * See spc4r17 section 6.14 Table 170
     */
    sense_reason_t
    target_scsi3_emulate_pr_out(struct se_cmd *cmd)
    {
    	unsigned char *cdb = &cmd->t_task_cdb[0];
    	unsigned char *buf;
    	u64 res_key, sa_res_key;
    	int sa, scope, type, aptpl;
    	int spec_i_pt = 0, all_tg_pt = 0, unreg = 0;
    	sense_reason_t ret;
    
    	/*
    	 * Following spc2r20 5.5.1 Reservations overview:
    	 *
    	 * If a logical unit has been reserved by any RESERVE command and is
    	 * still reserved by any initiator, all PERSISTENT RESERVE IN and all
    	 * PERSISTENT RESERVE OUT commands shall conflict regardless of
    	 * initiator or service action and shall terminate with a RESERVATION
    	 * CONFLICT status.
    	 */
    	if (cmd->se_dev->dev_reservation_flags & DRF_SPC2_RESERVATIONS) {
    		pr_err("Received PERSISTENT_RESERVE CDB while legacy"
    			" SPC-2 reservation is held, returning"
    			" RESERVATION_CONFLICT\n");
    		return TCM_RESERVATION_CONFLICT;
    	}
    
    	/*
    	 * FIXME: A NULL struct se_session pointer means an this is not coming from
    	 * a $FABRIC_MOD's nexus, but from internal passthrough ops.
    	 */
    	if (!cmd->se_sess)
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    
    	if (cmd->data_length < 24) {
    		pr_warn("SPC-PR: Received PR OUT parameter list"
    			" length too small: %u\n", cmd->data_length);
    		return TCM_INVALID_PARAMETER_LIST;
    	}
    
    	/*
    	 * From the PERSISTENT_RESERVE_OUT command descriptor block (CDB)
    	 */
    	sa = (cdb[1] & 0x1f);
    	scope = (cdb[2] & 0xf0);
    	type = (cdb[2] & 0x0f);
    
    	buf = transport_kmap_data_sg(cmd);
    	if (!buf)
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    
    	/*
    	 * From PERSISTENT_RESERVE_OUT parameter list (payload)
    	 */
    	res_key = core_scsi3_extract_reservation_key(&buf[0]);
    	sa_res_key = core_scsi3_extract_reservation_key(&buf[8]);
    	/*
    	 * REGISTER_AND_MOVE uses a different SA parameter list containing
    	 * SCSI TransportIDs.
    	 */
    	if (sa != PRO_REGISTER_AND_MOVE) {
    		spec_i_pt = (buf[20] & 0x08);
    		all_tg_pt = (buf[20] & 0x04);
    		aptpl = (buf[20] & 0x01);
    	} else {
    		aptpl = (buf[17] & 0x01);
    		unreg = (buf[17] & 0x02);
    	}
    	transport_kunmap_data_sg(cmd);
    	buf = NULL;
    
    	/*
    	 * SPEC_I_PT=1 is only valid for Service action: REGISTER
    	 */
    	if (spec_i_pt && ((cdb[1] & 0x1f) != PRO_REGISTER))
    		return TCM_INVALID_PARAMETER_LIST;
    
    	/*
    	 * From spc4r17 section 6.14:
    	 *
    	 * If the SPEC_I_PT bit is set to zero, the service action is not
    	 * REGISTER AND MOVE, and the parameter list length is not 24, then
    	 * the command shall be terminated with CHECK CONDITION status, with
    	 * the sense key set to ILLEGAL REQUEST, and the additional sense
    	 * code set to PARAMETER LIST LENGTH ERROR.
    	 */
    	if (!spec_i_pt && ((cdb[1] & 0x1f) != PRO_REGISTER_AND_MOVE) &&
    	    (cmd->data_length != 24)) {
    		pr_warn("SPC-PR: Received PR OUT illegal parameter"
    			" list length: %u\n", cmd->data_length);
    		return TCM_INVALID_PARAMETER_LIST;
    	}
    
    	/*
    	 * (core_scsi3_emulate_pro_* function parameters
    	 * are defined by spc4r17 Table 174:
    	 * PERSISTENT_RESERVE_OUT service actions and valid parameters.
    	 */
    	switch (sa) {
    	case PRO_REGISTER:
    		ret = core_scsi3_emulate_pro_register(cmd,
    			res_key, sa_res_key, aptpl, all_tg_pt, spec_i_pt, 0);
    		break;
    	case PRO_RESERVE:
    		ret = core_scsi3_emulate_pro_reserve(cmd, type, scope, res_key);
    		break;
    	case PRO_RELEASE:
    		ret = core_scsi3_emulate_pro_release(cmd, type, scope, res_key);
    		break;
    	case PRO_CLEAR:
    		ret = core_scsi3_emulate_pro_clear(cmd, res_key);
    		break;
    	case PRO_PREEMPT:
    		ret = core_scsi3_emulate_pro_preempt(cmd, type, scope,
    					res_key, sa_res_key, 0);
    		break;
    	case PRO_PREEMPT_AND_ABORT:
    		ret = core_scsi3_emulate_pro_preempt(cmd, type, scope,
    					res_key, sa_res_key, 1);
    		break;
    	case PRO_REGISTER_AND_IGNORE_EXISTING_KEY:
    		ret = core_scsi3_emulate_pro_register(cmd,
    			0, sa_res_key, aptpl, all_tg_pt, spec_i_pt, 1);
    		break;
    	case PRO_REGISTER_AND_MOVE:
    		ret = core_scsi3_emulate_pro_register_and_move(cmd, res_key,
    				sa_res_key, aptpl, unreg);
    		break;
    	default:
    		pr_err("Unknown PERSISTENT_RESERVE_OUT service"
    			" action: 0x%02x\n", cdb[1] & 0x1f);
    		return TCM_INVALID_CDB_FIELD;
    	}
    
    	if (!ret)
    		target_complete_cmd(cmd, GOOD);
    	return ret;
    }
    
    /*
     * PERSISTENT_RESERVE_IN Service Action READ_KEYS
     *
     * See spc4r17 section 5.7.6.2 and section 6.13.2, Table 160
     */
    static sense_reason_t
    core_scsi3_pri_read_keys(struct se_cmd *cmd)
    {
    	struct se_device *dev = cmd->se_dev;
    	struct t10_pr_registration *pr_reg;
    	unsigned char *buf;
    	u32 add_len = 0, off = 8;
    
    	if (cmd->data_length < 8) {
    		pr_err("PRIN SA READ_KEYS SCSI Data Length: %u"
    			" too small\n", cmd->data_length);
    		return TCM_INVALID_CDB_FIELD;
    	}
    
    	buf = transport_kmap_data_sg(cmd);
    	if (!buf)
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    
    	buf[0] = ((dev->t10_pr.pr_generation >> 24) & 0xff);
    	buf[1] = ((dev->t10_pr.pr_generation >> 16) & 0xff);
    	buf[2] = ((dev->t10_pr.pr_generation >> 8) & 0xff);
    	buf[3] = (dev->t10_pr.pr_generation & 0xff);
    
    	spin_lock(&dev->t10_pr.registration_lock);
    	list_for_each_entry(pr_reg, &dev->t10_pr.registration_list,
    			pr_reg_list) {
    		/*
    		 * Check for overflow of 8byte PRI READ_KEYS payload and
    		 * next reservation key list descriptor.
    		 */
    		if ((add_len + 8) > (cmd->data_length - 8))
    			break;
    
    		buf[off++] = ((pr_reg->pr_res_key >> 56) & 0xff);
    		buf[off++] = ((pr_reg->pr_res_key >> 48) & 0xff);
    		buf[off++] = ((pr_reg->pr_res_key >> 40) & 0xff);
    		buf[off++] = ((pr_reg->pr_res_key >> 32) & 0xff);
    		buf[off++] = ((pr_reg->pr_res_key >> 24) & 0xff);
    		buf[off++] = ((pr_reg->pr_res_key >> 16) & 0xff);
    		buf[off++] = ((pr_reg->pr_res_key >> 8) & 0xff);
    		buf[off++] = (pr_reg->pr_res_key & 0xff);
    
    		add_len += 8;
    	}
    	spin_unlock(&dev->t10_pr.registration_lock);
    
    	buf[4] = ((add_len >> 24) & 0xff);
    	buf[5] = ((add_len >> 16) & 0xff);
    	buf[6] = ((add_len >> 8) & 0xff);
    	buf[7] = (add_len & 0xff);
    
    	transport_kunmap_data_sg(cmd);
    
    	return 0;
    }
    
    /*
     * PERSISTENT_RESERVE_IN Service Action READ_RESERVATION
     *
     * See spc4r17 section 5.7.6.3 and section 6.13.3.2 Table 161 and 162
     */
    static sense_reason_t
    core_scsi3_pri_read_reservation(struct se_cmd *cmd)
    {
    	struct se_device *dev = cmd->se_dev;
    	struct t10_pr_registration *pr_reg;
    	unsigned char *buf;
    	u64 pr_res_key;
    	u32 add_len = 16; /* Hardcoded to 16 when a reservation is held. */
    
    	if (cmd->data_length < 8) {
    		pr_err("PRIN SA READ_RESERVATIONS SCSI Data Length: %u"
    			" too small\n", cmd->data_length);
    		return TCM_INVALID_CDB_FIELD;
    	}
    
    	buf = transport_kmap_data_sg(cmd);
    	if (!buf)
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    
    	buf[0] = ((dev->t10_pr.pr_generation >> 24) & 0xff);
    	buf[1] = ((dev->t10_pr.pr_generation >> 16) & 0xff);
    	buf[2] = ((dev->t10_pr.pr_generation >> 8) & 0xff);
    	buf[3] = (dev->t10_pr.pr_generation & 0xff);
    
    	spin_lock(&dev->dev_reservation_lock);
    	pr_reg = dev->dev_pr_res_holder;
    	if (pr_reg) {
    		/*
    		 * Set the hardcoded Additional Length
    		 */
    		buf[4] = ((add_len >> 24) & 0xff);
    		buf[5] = ((add_len >> 16) & 0xff);
    		buf[6] = ((add_len >> 8) & 0xff);
    		buf[7] = (add_len & 0xff);
    
    		if (cmd->data_length < 22)
    			goto err;
    
    		/*
    		 * Set the Reservation key.
    		 *
    		 * From spc4r17, section 5.7.10:
    		 * A persistent reservation holder has its reservation key
    		 * returned in the parameter data from a PERSISTENT
    		 * RESERVE IN command with READ RESERVATION service action as
    		 * follows:
    		 * a) For a persistent reservation of the type Write Exclusive
    		 *    - All Registrants or Exclusive Access ­ All Regitrants,
    		 *      the reservation key shall be set to zero; or
    		 * b) For all other persistent reservation types, the
    		 *    reservation key shall be set to the registered
    		 *    reservation key for the I_T nexus that holds the
    		 *    persistent reservation.
    		 */
    		if ((pr_reg->pr_res_type == PR_TYPE_WRITE_EXCLUSIVE_ALLREG) ||
    		    (pr_reg->pr_res_type == PR_TYPE_EXCLUSIVE_ACCESS_ALLREG))
    			pr_res_key = 0;
    		else
    			pr_res_key = pr_reg->pr_res_key;
    
    		buf[8] = ((pr_res_key >> 56) & 0xff);
    		buf[9] = ((pr_res_key >> 48) & 0xff);
    		buf[10] = ((pr_res_key >> 40) & 0xff);
    		buf[11] = ((pr_res_key >> 32) & 0xff);
    		buf[12] = ((pr_res_key >> 24) & 0xff);
    		buf[13] = ((pr_res_key >> 16) & 0xff);
    		buf[14] = ((pr_res_key >> 8) & 0xff);
    		buf[15] = (pr_res_key & 0xff);
    		/*
    		 * Set the SCOPE and TYPE
    		 */
    		buf[21] = (pr_reg->pr_res_scope & 0xf0) |
    			  (pr_reg->pr_res_type & 0x0f);
    	}
    
    err:
    	spin_unlock(&dev->dev_reservation_lock);
    	transport_kunmap_data_sg(cmd);
    
    	return 0;
    }
    
    /*
     * PERSISTENT_RESERVE_IN Service Action REPORT_CAPABILITIES
     *
     * See spc4r17 section 6.13.4 Table 165
     */
    static sense_reason_t
    core_scsi3_pri_report_capabilities(struct se_cmd *cmd)
    {
    	struct se_device *dev = cmd->se_dev;
    	struct t10_reservation *pr_tmpl = &dev->t10_pr;
    	unsigned char *buf;
    	u16 add_len = 8; /* Hardcoded to 8. */
    
    	if (cmd->data_length < 6) {
    		pr_err("PRIN SA REPORT_CAPABILITIES SCSI Data Length:"
    			" %u too small\n", cmd->data_length);
    		return TCM_INVALID_CDB_FIELD;
    	}
    
    	buf = transport_kmap_data_sg(cmd);
    	if (!buf)
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    
    	buf[0] = ((add_len << 8) & 0xff);
    	buf[1] = (add_len & 0xff);
    	buf[2] |= 0x10; /* CRH: Compatible Reservation Hanlding bit. */
    	buf[2] |= 0x08; /* SIP_C: Specify Initiator Ports Capable bit */
    	buf[2] |= 0x04; /* ATP_C: All Target Ports Capable bit */
    	buf[2] |= 0x01; /* PTPL_C: Persistence across Target Power Loss bit */
    	/*
    	 * We are filling in the PERSISTENT RESERVATION TYPE MASK below, so
    	 * set the TMV: Task Mask Valid bit.
    	 */
    	buf[3] |= 0x80;
    	/*
    	 * Change ALLOW COMMANDs to 0x20 or 0x40 later from Table 166
    	 */
    	buf[3] |= 0x10; /* ALLOW COMMANDs field 001b */
    	/*
    	 * PTPL_A: Persistence across Target Power Loss Active bit
    	 */
    	if (pr_tmpl->pr_aptpl_active)
    		buf[3] |= 0x01;
    	/*
    	 * Setup the PERSISTENT RESERVATION TYPE MASK from Table 167
    	 */
    	buf[4] |= 0x80; /* PR_TYPE_EXCLUSIVE_ACCESS_ALLREG */
    	buf[4] |= 0x40; /* PR_TYPE_EXCLUSIVE_ACCESS_REGONLY */
    	buf[4] |= 0x20; /* PR_TYPE_WRITE_EXCLUSIVE_REGONLY */
    	buf[4] |= 0x08; /* PR_TYPE_EXCLUSIVE_ACCESS */
    	buf[4] |= 0x02; /* PR_TYPE_WRITE_EXCLUSIVE */
    	buf[5] |= 0x01; /* PR_TYPE_EXCLUSIVE_ACCESS_ALLREG */
    
    	transport_kunmap_data_sg(cmd);
    
    	return 0;
    }
    
    /*
     * PERSISTENT_RESERVE_IN Service Action READ_FULL_STATUS
     *
     * See spc4r17 section 6.13.5 Table 168 and 169
     */
    static sense_reason_t
    core_scsi3_pri_read_full_status(struct se_cmd *cmd)
    {
    	struct se_device *dev = cmd->se_dev;
    	struct se_node_acl *se_nacl;
    	struct se_portal_group *se_tpg;
    	struct t10_pr_registration *pr_reg, *pr_reg_tmp;
    	struct t10_reservation *pr_tmpl = &dev->t10_pr;
    	unsigned char *buf;
    	u32 add_desc_len = 0, add_len = 0, desc_len, exp_desc_len;
    	u32 off = 8; /* off into first Full Status descriptor */
    	int format_code = 0;
    
    	if (cmd->data_length < 8) {
    		pr_err("PRIN SA READ_FULL_STATUS SCSI Data Length: %u"
    			" too small\n", cmd->data_length);
    		return TCM_INVALID_CDB_FIELD;
    	}
    
    	buf = transport_kmap_data_sg(cmd);
    	if (!buf)
    		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
    
    	buf[0] = ((dev->t10_pr.pr_generation >> 24) & 0xff);
    	buf[1] = ((dev->t10_pr.pr_generation >> 16) & 0xff);
    	buf[2] = ((dev->t10_pr.pr_generation >> 8) & 0xff);
    	buf[3] = (dev->t10_pr.pr_generation & 0xff);
    
    	spin_lock(&pr_tmpl->registration_lock);
    	list_for_each_entry_safe(pr_reg, pr_reg_tmp,
    			&pr_tmpl->registration_list, pr_reg_list) {
    
    		se_nacl = pr_reg->pr_reg_nacl;
    		se_tpg = pr_reg->pr_reg_nacl->se_tpg;
    		add_desc_len = 0;
    
    		atomic_inc(&pr_reg->pr_res_holders);
    		smp_mb__after_atomic_inc();
    		spin_unlock(&pr_tmpl->registration_lock);
    		/*
    		 * Determine expected length of $FABRIC_MOD specific
    		 * TransportID full status descriptor..
    		 */
    		exp_desc_len = se_tpg->se_tpg_tfo->tpg_get_pr_transport_id_len(
    				se_tpg, se_nacl, pr_reg, &format_code);
    
    		if ((exp_desc_len + add_len) > cmd->data_length) {
    			pr_warn("SPC-3 PRIN READ_FULL_STATUS ran"
    				" out of buffer: %d\n", cmd->data_length);
    			spin_lock(&pr_tmpl->registration_lock);
    			atomic_dec(&pr_reg->pr_res_holders);
    			smp_mb__after_atomic_dec();
    			break;
    		}
    		/*
    		 * Set RESERVATION KEY
    		 */
    		buf[off++] = ((pr_reg->pr_res_key >> 56) & 0xff);
    		buf[off++] = ((pr_reg->pr_res_key >> 48) & 0xff);
    		buf[off++] = ((pr_reg->pr_res_key >> 40) & 0xff);
    		buf[off++] = ((pr_reg->pr_res_key >> 32) & 0xff);
    		buf[off++] = ((pr_reg->pr_res_key >> 24) & 0xff);
    		buf[off++] = ((pr_reg->pr_res_key >> 16) & 0xff);
    		buf[off++] = ((pr_reg->pr_res_key >> 8) & 0xff);
    		buf[off++] = (pr_reg->pr_res_key & 0xff);
    		off += 4; /* Skip Over Reserved area */
    
    		/*
    		 * Set ALL_TG_PT bit if PROUT SA REGISTER had this set.
    		 */
    		if (pr_reg->pr_reg_all_tg_pt)
    			buf[off] = 0x02;
    		/*
    		 * The struct se_lun pointer will be present for the
    		 * reservation holder for PR_HOLDER bit.
    		 *
    		 * Also, if this registration is the reservation
    		 * holder, fill in SCOPE and TYPE in the next byte.
    		 */
    		if (pr_reg->pr_res_holder) {
    			buf[off++] |= 0x01;
    			buf[off++] = (pr_reg->pr_res_scope & 0xf0) |
    				     (pr_reg->pr_res_type & 0x0f);
    		} else
    			off += 2;
    
    		off += 4; /* Skip over reserved area */
    		/*
    		 * From spc4r17 6.3.15:
    		 *
    		 * If the ALL_TG_PT bit set to zero, the RELATIVE TARGET PORT
    		 * IDENTIFIER field contains the relative port identifier (see
    		 * 3.1.120) of the target port that is part of the I_T nexus
    		 * described by this full status descriptor. If the ALL_TG_PT
    		 * bit is set to one, the contents of the RELATIVE TARGET PORT
    		 * IDENTIFIER field are not defined by this standard.
    		 */
    		if (!pr_reg->pr_reg_all_tg_pt) {
    			struct se_port *port = pr_reg->pr_reg_tg_pt_lun->lun_sep;
    
    			buf[off++] = ((port->sep_rtpi >> 8) & 0xff);
    			buf[off++] = (port->sep_rtpi & 0xff);
    		} else
    			off += 2; /* Skip over RELATIVE TARGET PORT IDENTIFIER */
    
    		/*
    		 * Now, have the $FABRIC_MOD fill in the protocol identifier
    		 */
    		desc_len = se_tpg->se_tpg_tfo->tpg_get_pr_transport_id(se_tpg,
    				se_nacl, pr_reg, &format_code, &buf[off+4]);
    
    		spin_lock(&pr_tmpl->registration_lock);
    		atomic_dec(&pr_reg->pr_res_holders);
    		smp_mb__after_atomic_dec();
    		/*
    		 * Set the ADDITIONAL DESCRIPTOR LENGTH
    		 */
    		buf[off++] = ((desc_len >> 24) & 0xff);
    		buf[off++] = ((desc_len >> 16) & 0xff);
    		buf[off++] = ((desc_len >> 8) & 0xff);
    		buf[off++] = (desc_len & 0xff);
    		/*
    		 * Size of full desctipor header minus TransportID
    		 * containing $FABRIC_MOD specific) initiator device/port
    		 * WWN information.
    		 *
    		 *  See spc4r17 Section 6.13.5 Table 169
    		 */
    		add_desc_len = (24 + desc_len);
    
    		off += desc_len;
    		add_len += add_desc_len;
    	}
    	spin_unlock(&pr_tmpl->registration_lock);
    	/*
    	 * Set ADDITIONAL_LENGTH
    	 */
    	buf[4] = ((add_len >> 24) & 0xff);
    	buf[5] = ((add_len >> 16) & 0xff);
    	buf[6] = ((add_len >> 8) & 0xff);
    	buf[7] = (add_len & 0xff);
    
    	transport_kunmap_data_sg(cmd);
    
    	return 0;
    }
    
    sense_reason_t
    target_scsi3_emulate_pr_in(struct se_cmd *cmd)
    {
    	sense_reason_t ret;
    
    	/*
    	 * Following spc2r20 5.5.1 Reservations overview:
    	 *
    	 * If a logical unit has been reserved by any RESERVE command and is
    	 * still reserved by any initiator, all PERSISTENT RESERVE IN and all
    	 * PERSISTENT RESERVE OUT commands shall conflict regardless of
    	 * initiator or service action and shall terminate with a RESERVATION
    	 * CONFLICT status.
    	 */
    	if (cmd->se_dev->dev_reservation_flags & DRF_SPC2_RESERVATIONS) {
    		pr_err("Received PERSISTENT_RESERVE CDB while legacy"
    			" SPC-2 reservation is held, returning"
    			" RESERVATION_CONFLICT\n");
    		return TCM_RESERVATION_CONFLICT;
    	}
    
    	switch (cmd->t_task_cdb[1] & 0x1f) {
    	case PRI_READ_KEYS:
    		ret = core_scsi3_pri_read_keys(cmd);
    		break;
    	case PRI_READ_RESERVATION:
    		ret = core_scsi3_pri_read_reservation(cmd);
    		break;
    	case PRI_REPORT_CAPABILITIES:
    		ret = core_scsi3_pri_report_capabilities(cmd);
    		break;
    	case PRI_READ_FULL_STATUS:
    		ret = core_scsi3_pri_read_full_status(cmd);
    		break;
    	default:
    		pr_err("Unknown PERSISTENT_RESERVE_IN service"
    			" action: 0x%02x\n", cmd->t_task_cdb[1] & 0x1f);
    		return TCM_INVALID_CDB_FIELD;
    	}
    
    	if (!ret)
    		target_complete_cmd(cmd, GOOD);
    	return ret;
    }
    
    sense_reason_t
    target_check_reservation(struct se_cmd *cmd)
    {
    	struct se_device *dev = cmd->se_dev;
    	sense_reason_t ret;
    
    	if (!cmd->se_sess)
    		return 0;
    	if (dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE)
    		return 0;
    	if (dev->transport->transport_type == TRANSPORT_PLUGIN_PHBA_PDEV)
    		return 0;
    
    	spin_lock(&dev->dev_reservation_lock);
    	if (dev->dev_reservation_flags & DRF_SPC2_RESERVATIONS)
    		ret = target_scsi2_reservation_check(cmd);
    	else
    		ret = target_scsi3_pr_reservation_check(cmd);
    	spin_unlock(&dev->dev_reservation_lock);
    
    	return ret;
    }