/*******************************************************************************
 * Filename:  target_core_alua.c
 *
 * This file contains SPC-3 compliant asymmetric logical unit assigntment (ALUA)
 *
 * (c) Copyright 2009-2013 Datera, Inc.
 *
 * Nicholas A. Bellinger <nab@kernel.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 ******************************************************************************/

#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/configfs.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <scsi/scsi_proto.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_core_internal.h"
#include "target_core_alua.h"
#include "target_core_ua.h"

static sense_reason_t core_alua_check_transition(int state, int valid,
                                                 int *primary, int explicit);
static int core_alua_set_tg_pt_secondary_state(
                struct se_lun *lun, int explicit, int offline);

static char *core_alua_dump_state(int state);

static void __target_attach_tg_pt_gp(struct se_lun *lun,
                struct t10_alua_tg_pt_gp *tg_pt_gp);

static u16 alua_lu_gps_counter;
static u32 alua_lu_gps_count;

static DEFINE_SPINLOCK(lu_gps_lock);
static LIST_HEAD(lu_gps_list);

struct t10_alua_lu_gp *default_lu_gp;

/*
 * REPORT REFERRALS
 *
 * See sbc3r35 section 5.23
 */
sense_reason_t
target_emulate_report_referrals(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        struct t10_alua_lba_map *map;
        struct t10_alua_lba_map_member *map_mem;
        unsigned char *buf;
        u32 rd_len = 0, off;

        if (cmd->data_length < 4) {
                pr_warn("REPORT REFERRALS allocation 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;

        off = 4;
        spin_lock(&dev->t10_alua.lba_map_lock);
        if (list_empty(&dev->t10_alua.lba_map_list)) {
                spin_unlock(&dev->t10_alua.lba_map_lock);
                transport_kunmap_data_sg(cmd);

                return TCM_UNSUPPORTED_SCSI_OPCODE;
        }

        list_for_each_entry(map, &dev->t10_alua.lba_map_list,
                            lba_map_list) {
                int desc_num = off + 3;
                int pg_num;

                off += 4;
                if (cmd->data_length > off)
                        put_unaligned_be64(map->lba_map_first_lba, &buf[off]);
                off += 8;
                if (cmd->data_length > off)
                        put_unaligned_be64(map->lba_map_last_lba, &buf[off]);
                off += 8;
                rd_len += 20;
                pg_num = 0;
                list_for_each_entry(map_mem, &map->lba_map_mem_list,
                                    lba_map_mem_list) {
                        int alua_state = map_mem->lba_map_mem_alua_state;
                        int alua_pg_id = map_mem->lba_map_mem_alua_pg_id;

                        if (cmd->data_length > off)
                                buf[off] = alua_state & 0x0f;
                        off += 2;
                        if (cmd->data_length > off)
                                buf[off] = (alua_pg_id >> 8) & 0xff;
                        off++;
                        if (cmd->data_length > off)
                                buf[off] = (alua_pg_id & 0xff);
                        off++;
                        rd_len += 4;
                        pg_num++;
                }
                if (cmd->data_length > desc_num)
                        buf[desc_num] = pg_num;
        }
        spin_unlock(&dev->t10_alua.lba_map_lock);

        /*
         * Set the RETURN DATA LENGTH set in the header of the DataIN Payload
         */
        put_unaligned_be16(rd_len, &buf[2]);

        transport_kunmap_data_sg(cmd);

        target_complete_cmd(cmd, GOOD);
        return 0;
}

/*
 * REPORT_TARGET_PORT_GROUPS
 *
 * See spc4r17 section 6.27
 */
sense_reason_t
target_emulate_report_target_port_groups(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        struct t10_alua_tg_pt_gp *tg_pt_gp;
        struct se_lun *lun;
        unsigned char *buf;
        u32 rd_len = 0, off;
        int ext_hdr = (cmd->t_task_cdb[1] & 0x20);

        /*
         * Skip over RESERVED area to first Target port group descriptor
         * depending on the PARAMETER DATA FORMAT type..
         */
        if (ext_hdr != 0)
                off = 8;
        else
                off = 4;

        if (cmd->data_length < off) {
                pr_warn("REPORT TARGET PORT GROUPS allocation length %u too"
                        " small for %s header\n", cmd->data_length,
                        (ext_hdr) ? "extended" : "normal");
                return TCM_INVALID_CDB_FIELD;
        }
        buf = transport_kmap_data_sg(cmd);
        if (!buf)
                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

        spin_lock(&dev->t10_alua.tg_pt_gps_lock);
        list_for_each_entry(tg_pt_gp, &dev->t10_alua.tg_pt_gps_list,
                        tg_pt_gp_list) {
                /*
                 * Check if the Target port group and Target port descriptor list
                 * based on tg_pt_gp_members count will fit into the response payload.
                 * Otherwise, bump rd_len to let the initiator know we have exceeded
                 * the allocation length and the response is truncated.
                 */
                if ((off + 8 + (tg_pt_gp->tg_pt_gp_members * 4)) >
                     cmd->data_length) {
                        rd_len += 8 + (tg_pt_gp->tg_pt_gp_members * 4);
                        continue;
                }
                /*
                 * PREF: Preferred target port bit, determine if this
                 * bit should be set for port group.
                 */
                if (tg_pt_gp->tg_pt_gp_pref)
                        buf[off] = 0x80;
                /*
                 * Set the ASYMMETRIC ACCESS State
                 */
                buf[off++] |= tg_pt_gp->tg_pt_gp_alua_access_state & 0xff;
                /*
                 * Set supported ASYMMETRIC ACCESS State bits
                 */
                buf[off++] |= tg_pt_gp->tg_pt_gp_alua_supported_states;
                /*
                 * TARGET PORT GROUP
                 */
                put_unaligned_be16(tg_pt_gp->tg_pt_gp_id, &buf[off]);
                off += 2;

                off++; /* Skip over Reserved */
                /*
                 * STATUS CODE
                 */
                buf[off++] = (tg_pt_gp->tg_pt_gp_alua_access_status & 0xff);
                /*
                 * Vendor Specific field
                 */
                buf[off++] = 0x00;
                /*
                 * TARGET PORT COUNT
                 */
                buf[off++] = (tg_pt_gp->tg_pt_gp_members & 0xff);
                rd_len += 8;

                spin_lock(&tg_pt_gp->tg_pt_gp_lock);
                list_for_each_entry(lun, &tg_pt_gp->tg_pt_gp_lun_list,
                                lun_tg_pt_gp_link) {
                        /*
                         * Start Target Port descriptor format
                         *
                         * See spc4r17 section 6.2.7 Table 247
                         */
                        off += 2; /* Skip over Obsolete */
                        /*
                         * Set RELATIVE TARGET PORT IDENTIFIER
                         */
                        put_unaligned_be16(lun->lun_rtpi, &buf[off]);
                        off += 2;
                        rd_len += 4;
                }
                spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
        }
        spin_unlock(&dev->t10_alua.tg_pt_gps_lock);
        /*
         * Set the RETURN DATA LENGTH set in the header of the DataIN Payload
         */
        put_unaligned_be32(rd_len, &buf[0]);

        /*
         * Fill in the Extended header parameter data format if requested
         */
        if (ext_hdr != 0) {
                buf[4] = 0x10;
                /*
                 * Set the implicit transition time (in seconds) for the application
                 * client to use as a base for it's transition timeout value.
                 *
                 * Use the current tg_pt_gp_mem -> tg_pt_gp membership from the LUN
                 * this CDB was received upon to determine this value individually
                 * for ALUA target port group.
                 */
                spin_lock(&cmd->se_lun->lun_tg_pt_gp_lock);
                tg_pt_gp = cmd->se_lun->lun_tg_pt_gp;
                if (tg_pt_gp)
                        buf[5] = tg_pt_gp->tg_pt_gp_implicit_trans_secs;
                spin_unlock(&cmd->se_lun->lun_tg_pt_gp_lock);
        }
        transport_kunmap_data_sg(cmd);

        target_complete_cmd(cmd, GOOD);
        return 0;
}

/*
 * SET_TARGET_PORT_GROUPS for explicit ALUA operation.
 *
 * See spc4r17 section 6.35
 */
sense_reason_t
target_emulate_set_target_port_groups(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        struct se_lun *l_lun = cmd->se_lun;
        struct se_node_acl *nacl = cmd->se_sess->se_node_acl;
        struct t10_alua_tg_pt_gp *tg_pt_gp = NULL, *l_tg_pt_gp;
        unsigned char *buf;
        unsigned char *ptr;
        sense_reason_t rc = TCM_NO_SENSE;
        u32 len = 4; /* Skip over RESERVED area in header */
        int alua_access_state, primary = 0, valid_states;
        u16 tg_pt_id, rtpi;

        if (cmd->data_length < 4) {
                pr_warn("SET TARGET PORT GROUPS parameter list length %u too"
                        " small\n", cmd->data_length);
                return TCM_INVALID_PARAMETER_LIST;
        }

        buf = transport_kmap_data_sg(cmd);
        if (!buf)
                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

        /*
         * Determine if explicit ALUA via SET_TARGET_PORT_GROUPS is allowed
         * for the local tg_pt_gp.
         */
        spin_lock(&l_lun->lun_tg_pt_gp_lock);
        l_tg_pt_gp = l_lun->lun_tg_pt_gp;
        if (!l_tg_pt_gp) {
                spin_unlock(&l_lun->lun_tg_pt_gp_lock);
                pr_err("Unable to access l_lun->tg_pt_gp\n");
                rc = TCM_UNSUPPORTED_SCSI_OPCODE;
                goto out;
        }

        if (!(l_tg_pt_gp->tg_pt_gp_alua_access_type & TPGS_EXPLICIT_ALUA)) {
                spin_unlock(&l_lun->lun_tg_pt_gp_lock);
                pr_debug("Unable to process SET_TARGET_PORT_GROUPS"
                                " while TPGS_EXPLICIT_ALUA is disabled\n");
                rc = TCM_UNSUPPORTED_SCSI_OPCODE;
                goto out;
        }
        valid_states = l_tg_pt_gp->tg_pt_gp_alua_supported_states;
        spin_unlock(&l_lun->lun_tg_pt_gp_lock);

        ptr = &buf[4]; /* Skip over RESERVED area in header */

        while (len < cmd->data_length) {
                bool found = false;
                alua_access_state = (ptr[0] & 0x0f);
                /*
                 * Check the received ALUA access state, and determine if
                 * the state is a primary or secondary target port asymmetric
                 * access state.
                 */
                rc = core_alua_check_transition(alua_access_state, valid_states,
                                                &primary, 1);
                if (rc) {
                        /*
                         * If the SET TARGET PORT GROUPS attempts to establish
                         * an invalid combination of target port asymmetric
                         * access states or attempts to establish an
                         * unsupported target port asymmetric access state,
                         * 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.
                         */
                        goto out;
                }

                /*
                 * If the ASYMMETRIC ACCESS STATE field (see table 267)
                 * specifies a primary target port asymmetric access state,
                 * then the TARGET PORT GROUP OR TARGET PORT field specifies
                 * a primary target port group for which the primary target
                 * port asymmetric access state shall be changed. If the
                 * ASYMMETRIC ACCESS STATE field specifies a secondary target
                 * port asymmetric access state, then the TARGET PORT GROUP OR
                 * TARGET PORT field specifies the relative target port
                 * identifier (see 3.1.120) of the target port for which the
                 * secondary target port asymmetric access state shall be
                 * changed.
                 */
                if (primary) {
                        tg_pt_id = get_unaligned_be16(ptr + 2);
                        /*
                         * Locate the matching target port group ID from
                         * the global tg_pt_gp list
                         */
                        spin_lock(&dev->t10_alua.tg_pt_gps_lock);
                        list_for_each_entry(tg_pt_gp,
                                        &dev->t10_alua.tg_pt_gps_list,
                                        tg_pt_gp_list) {
                                if (!tg_pt_gp->tg_pt_gp_valid_id)
                                        continue;

                                if (tg_pt_id != tg_pt_gp->tg_pt_gp_id)
                                        continue;

                                atomic_inc_mb(&tg_pt_gp->tg_pt_gp_ref_cnt);

                                spin_unlock(&dev->t10_alua.tg_pt_gps_lock);

                                if (!core_alua_do_port_transition(tg_pt_gp,
                                                dev, l_lun, nacl,
                                                alua_access_state, 1))
                                        found = true;

                                spin_lock(&dev->t10_alua.tg_pt_gps_lock);
                                atomic_dec_mb(&tg_pt_gp->tg_pt_gp_ref_cnt);
                                break;
                        }
                        spin_unlock(&dev->t10_alua.tg_pt_gps_lock);
                } else {
                        struct se_lun *lun;

                        /*
                         * Extract the RELATIVE TARGET PORT IDENTIFIER to identify
                         * the Target Port in question for the the incoming
                         * SET_TARGET_PORT_GROUPS op.
                         */
                        rtpi = get_unaligned_be16(ptr + 2);
                        /*
                         * Locate the matching relative target port identifier
                         * for the struct se_device storage object.
                         */
                        spin_lock(&dev->se_port_lock);
                        list_for_each_entry(lun, &dev->dev_sep_list,
                                                        lun_dev_link) {
                                if (lun->lun_rtpi != rtpi)
                                        continue;

                                // XXX: racy unlock
                                spin_unlock(&dev->se_port_lock);

                                if (!core_alua_set_tg_pt_secondary_state(
                                                lun, 1, 1))
                                        found = true;

                                spin_lock(&dev->se_port_lock);
                                break;
                        }
                        spin_unlock(&dev->se_port_lock);
                }

                if (!found) {
                        rc = TCM_INVALID_PARAMETER_LIST;
                        goto out;
                }

                ptr += 4;
                len += 4;
        }

out:
        transport_kunmap_data_sg(cmd);
        if (!rc)
                target_complete_cmd(cmd, GOOD);
        return rc;
}

static inline void set_ascq(struct se_cmd *cmd, u8 alua_ascq)
{
        /*
         * Set SCSI additional sense code (ASC) to 'LUN Not Accessible';
         * The ALUA additional sense code qualifier (ASCQ) is determined
         * by the ALUA primary or secondary access state..
         */
        pr_debug("[%s]: ALUA TG Port not available, "
                "SenseKey: NOT_READY, ASC/ASCQ: "
                "0x04/0x%02x\n",
                cmd->se_tfo->get_fabric_name(), alua_ascq);

        cmd->scsi_asc = 0x04;
        cmd->scsi_ascq = alua_ascq;
}

static inline void core_alua_state_nonoptimized(
        struct se_cmd *cmd,
        unsigned char *cdb,
        int nonop_delay_msecs)
{
        /*
         * Set SCF_ALUA_NON_OPTIMIZED here, this value will be checked
         * later to determine if processing of this cmd needs to be
         * temporarily delayed for the Active/NonOptimized primary access state.
         */
        cmd->se_cmd_flags |= SCF_ALUA_NON_OPTIMIZED;
        cmd->alua_nonop_delay = nonop_delay_msecs;
}

static inline int core_alua_state_lba_dependent(
        struct se_cmd *cmd,
        struct t10_alua_tg_pt_gp *tg_pt_gp)
{
        struct se_device *dev = cmd->se_dev;
        u64 segment_size, segment_mult, sectors, lba;

        /* Only need to check for cdb actually containing LBAs */
        if (!(cmd->se_cmd_flags & SCF_SCSI_DATA_CDB))
                return 0;

        spin_lock(&dev->t10_alua.lba_map_lock);
        segment_size = dev->t10_alua.lba_map_segment_size;
        segment_mult = dev->t10_alua.lba_map_segment_multiplier;
        sectors = cmd->data_length / dev->dev_attrib.block_size;

        lba = cmd->t_task_lba;
        while (lba < cmd->t_task_lba + sectors) {
                struct t10_alua_lba_map *cur_map = NULL, *map;
                struct t10_alua_lba_map_member *map_mem;

                list_for_each_entry(map, &dev->t10_alua.lba_map_list,
                                    lba_map_list) {
                        u64 start_lba, last_lba;
                        u64 first_lba = map->lba_map_first_lba;

                        if (segment_mult) {
                                u64 tmp = lba;
                                start_lba = do_div(tmp, segment_size * segment_mult);

                                last_lba = first_lba + segment_size - 1;
                                if (start_lba >= first_lba &&
                                    start_lba <= last_lba) {
                                        lba += segment_size;
                                        cur_map = map;
                                        break;
                                }
                        } else {
                                last_lba = map->lba_map_last_lba;
                                if (lba >= first_lba && lba <= last_lba) {
                                        lba = last_lba + 1;
                                        cur_map = map;
                                        break;
                                }
                        }
                }
                if (!cur_map) {
                        spin_unlock(&dev->t10_alua.lba_map_lock);
                        set_ascq(cmd, ASCQ_04H_ALUA_TG_PT_UNAVAILABLE);
                        return 1;
                }
                list_for_each_entry(map_mem, &cur_map->lba_map_mem_list,
                                    lba_map_mem_list) {
                        if (map_mem->lba_map_mem_alua_pg_id !=
                            tg_pt_gp->tg_pt_gp_id)
                                continue;
                        switch(map_mem->lba_map_mem_alua_state) {
                        case ALUA_ACCESS_STATE_STANDBY:
                                spin_unlock(&dev->t10_alua.lba_map_lock);
                                set_ascq(cmd, ASCQ_04H_ALUA_TG_PT_STANDBY);
                                return 1;
                        case ALUA_ACCESS_STATE_UNAVAILABLE:
                                spin_unlock(&dev->t10_alua.lba_map_lock);
                                set_ascq(cmd, ASCQ_04H_ALUA_TG_PT_UNAVAILABLE);
                                return 1;
                        default:
                                break;
                        }
                }
        }
        spin_unlock(&dev->t10_alua.lba_map_lock);
        return 0;
}

static inline int core_alua_state_standby(
        struct se_cmd *cmd,
        unsigned char *cdb)
{
        /*
         * Allowed CDBs for ALUA_ACCESS_STATE_STANDBY as defined by
         * spc4r17 section 5.9.2.4.4
         */
        switch (cdb[0]) {
        case INQUIRY:
        case LOG_SELECT:
        case LOG_SENSE:
        case MODE_SELECT:
        case MODE_SENSE:
        case REPORT_LUNS:
        case RECEIVE_DIAGNOSTIC:
        case SEND_DIAGNOSTIC:
        case READ_CAPACITY:
                return 0;
        case SERVICE_ACTION_IN_16:
                switch (cdb[1] & 0x1f) {
                case SAI_READ_CAPACITY_16:
                        return 0;
                default:
                        set_ascq(cmd, ASCQ_04H_ALUA_TG_PT_STANDBY);
                        return 1;
                }
        case MAINTENANCE_IN:
                switch (cdb[1] & 0x1f) {
                case MI_REPORT_TARGET_PGS:
                        return 0;
                default:
                        set_ascq(cmd, ASCQ_04H_ALUA_TG_PT_STANDBY);
                        return 1;
                }
        case MAINTENANCE_OUT:
                switch (cdb[1]) {
                case MO_SET_TARGET_PGS:
                        return 0;
                default:
                        set_ascq(cmd, ASCQ_04H_ALUA_TG_PT_STANDBY);
                        return 1;
                }
        case REQUEST_SENSE:
        case PERSISTENT_RESERVE_IN:
        case PERSISTENT_RESERVE_OUT:
        case READ_BUFFER:
        case WRITE_BUFFER:
                return 0;
        default:
                set_ascq(cmd, ASCQ_04H_ALUA_TG_PT_STANDBY);
                return 1;
        }

        return 0;
}

static inline int core_alua_state_unavailable(
        struct se_cmd *cmd,
        unsigned char *cdb)
{
        /*
         * Allowed CDBs for ALUA_ACCESS_STATE_UNAVAILABLE as defined by
         * spc4r17 section 5.9.2.4.5
         */
        switch (cdb[0]) {
        case INQUIRY:
        case REPORT_LUNS:
                return 0;
        case MAINTENANCE_IN:
                switch (cdb[1] & 0x1f) {
                case MI_REPORT_TARGET_PGS:
                        return 0;
                default:
                        set_ascq(cmd, ASCQ_04H_ALUA_TG_PT_UNAVAILABLE);
                        return 1;
                }
        case MAINTENANCE_OUT:
                switch (cdb[1]) {
                case MO_SET_TARGET_PGS:
                        return 0;
                default:
                        set_ascq(cmd, ASCQ_04H_ALUA_TG_PT_UNAVAILABLE);
                        return 1;
                }
        case REQUEST_SENSE:
        case READ_BUFFER:
        case WRITE_BUFFER:
                return 0;
        default:
                set_ascq(cmd, ASCQ_04H_ALUA_TG_PT_UNAVAILABLE);
                return 1;
        }

        return 0;
}

static inline int core_alua_state_transition(
        struct se_cmd *cmd,
        unsigned char *cdb)
{
        /*
         * Allowed CDBs for ALUA_ACCESS_STATE_TRANSITION as defined by
         * spc4r17 section 5.9.2.5
         */
        switch (cdb[0]) {
        case INQUIRY:
        case REPORT_LUNS:
                return 0;
        case MAINTENANCE_IN:
                switch (cdb[1] & 0x1f) {
                case MI_REPORT_TARGET_PGS:
                        return 0;
                default:
                        set_ascq(cmd, ASCQ_04H_ALUA_STATE_TRANSITION);
                        return 1;
                }
        case REQUEST_SENSE:
        case READ_BUFFER:
        case WRITE_BUFFER:
                return 0;
        default:
                set_ascq(cmd, ASCQ_04H_ALUA_STATE_TRANSITION);
                return 1;
        }

        return 0;
}

/*
 * return 1: Is used to signal LUN not accessible, and check condition/not ready
 * return 0: Used to signal success
 * return -1: Used to signal failure, and invalid cdb field
 */
sense_reason_t
target_alua_state_check(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        unsigned char *cdb = cmd->t_task_cdb;
        struct se_lun *lun = cmd->se_lun;
        struct t10_alua_tg_pt_gp *tg_pt_gp;
        int out_alua_state, nonop_delay_msecs;

        if (dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE)
                return 0;
        if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH_ALUA)
                return 0;

        /*
         * First, check for a struct se_port specific secondary ALUA target port
         * access state: OFFLINE
         */
        if (atomic_read(&lun->lun_tg_pt_secondary_offline)) {
                pr_debug("ALUA: Got secondary offline status for local"
                                " target port\n");
                set_ascq(cmd, ASCQ_04H_ALUA_OFFLINE);
                return TCM_CHECK_CONDITION_NOT_READY;
        }

        if (!lun->lun_tg_pt_gp)
                return 0;

        spin_lock(&lun->lun_tg_pt_gp_lock);
        tg_pt_gp = lun->lun_tg_pt_gp;
        out_alua_state = tg_pt_gp->tg_pt_gp_alua_access_state;
        nonop_delay_msecs = tg_pt_gp->tg_pt_gp_nonop_delay_msecs;

        // XXX: keeps using tg_pt_gp witout reference after unlock
        spin_unlock(&lun->lun_tg_pt_gp_lock);
        /*
         * Process ALUA_ACCESS_STATE_ACTIVE_OPTIMIZED in a separate conditional
         * statement so the compiler knows explicitly to check this case first.
         * For the Optimized ALUA access state case, we want to process the
         * incoming fabric cmd ASAP..
         */
        if (out_alua_state == ALUA_ACCESS_STATE_ACTIVE_OPTIMIZED)
                return 0;

        switch (out_alua_state) {
        case ALUA_ACCESS_STATE_ACTIVE_NON_OPTIMIZED:
                core_alua_state_nonoptimized(cmd, cdb, nonop_delay_msecs);
                break;
        case ALUA_ACCESS_STATE_STANDBY:
                if (core_alua_state_standby(cmd, cdb))
                        return TCM_CHECK_CONDITION_NOT_READY;
                break;
        case ALUA_ACCESS_STATE_UNAVAILABLE:
                if (core_alua_state_unavailable(cmd, cdb))
                        return TCM_CHECK_CONDITION_NOT_READY;
                break;
        case ALUA_ACCESS_STATE_TRANSITION:
                if (core_alua_state_transition(cmd, cdb))
                        return TCM_CHECK_CONDITION_NOT_READY;
                break;
        case ALUA_ACCESS_STATE_LBA_DEPENDENT:
                if (core_alua_state_lba_dependent(cmd, tg_pt_gp))
                        return TCM_CHECK_CONDITION_NOT_READY;
                break;
        /*
         * OFFLINE is a secondary ALUA target port group access state, that is
         * handled above with struct se_lun->lun_tg_pt_secondary_offline=1
         */
        case ALUA_ACCESS_STATE_OFFLINE:
        default:
                pr_err("Unknown ALUA access state: 0x%02x\n",
                                out_alua_state);
                return TCM_INVALID_CDB_FIELD;
        }

        return 0;
}

/*
 * Check implicit and explicit ALUA state change request.
 */
static sense_reason_t
core_alua_check_transition(int state, int valid, int *primary, int explicit)
{
        /*
         * OPTIMIZED, NON-OPTIMIZED, STANDBY and UNAVAILABLE are
         * defined as primary target port asymmetric access states.
         */
        switch (state) {
        case ALUA_ACCESS_STATE_ACTIVE_OPTIMIZED:
                if (!(valid & ALUA_AO_SUP))
                        goto not_supported;
                *primary = 1;
                break;
        case ALUA_ACCESS_STATE_ACTIVE_NON_OPTIMIZED:
                if (!(valid & ALUA_AN_SUP))
                        goto not_supported;
                *primary = 1;
                break;
        case ALUA_ACCESS_STATE_STANDBY:
                if (!(valid & ALUA_S_SUP))
                        goto not_supported;
                *primary = 1;
                break;
        case ALUA_ACCESS_STATE_UNAVAILABLE:
                if (!(valid & ALUA_U_SUP))
                        goto not_supported;
                *primary = 1;
                break;
        case ALUA_ACCESS_STATE_LBA_DEPENDENT:
                if (!(valid & ALUA_LBD_SUP))
                        goto not_supported;
                *primary = 1;
                break;
        case ALUA_ACCESS_STATE_OFFLINE:
                /*
                 * OFFLINE state is defined as a secondary target port
                 * asymmetric access state.
                 */
                if (!(valid & ALUA_O_SUP))
                        goto not_supported;
                *primary = 0;
                break;
        case ALUA_ACCESS_STATE_TRANSITION:
                if (!(valid & ALUA_T_SUP) || explicit)
                        /*
                         * Transitioning is set internally and by tcmu daemon,
                         * and cannot be selected through a STPG.
                         */
                        goto not_supported;
                *primary = 0;
                break;
        default:
                pr_err("Unknown ALUA access state: 0x%02x\n", state);
                return TCM_INVALID_PARAMETER_LIST;
        }

        return 0;

not_supported:
        pr_err("ALUA access state %s not supported",
               core_alua_dump_state(state));
        return TCM_INVALID_PARAMETER_LIST;
}

static char *core_alua_dump_state(int state)
{
        switch (state) {
        case ALUA_ACCESS_STATE_ACTIVE_OPTIMIZED:
                return "Active/Optimized";
        case ALUA_ACCESS_STATE_ACTIVE_NON_OPTIMIZED:
                return "Active/NonOptimized";
        case ALUA_ACCESS_STATE_LBA_DEPENDENT:
                return "LBA Dependent";
        case ALUA_ACCESS_STATE_STANDBY:
                return "Standby";
        case ALUA_ACCESS_STATE_UNAVAILABLE:
                return "Unavailable";
        case ALUA_ACCESS_STATE_OFFLINE:
                return "Offline";
        case ALUA_ACCESS_STATE_TRANSITION:
                return "Transitioning";
        default:
                return "Unknown";
        }

        return NULL;
}

char *core_alua_dump_status(int status)
{
        switch (status) {
        case ALUA_STATUS_NONE:
                return "None";
        case ALUA_STATUS_ALTERED_BY_EXPLICIT_STPG:
                return "Altered by Explicit STPG";
        case ALUA_STATUS_ALTERED_BY_IMPLICIT_ALUA:
                return "Altered by Implicit ALUA";
        default:
                return "Unknown";
        }

        return NULL;
}

/*
 * Used by fabric modules to determine when we need to delay processing
 * for the Active/NonOptimized paths..
 */
int core_alua_check_nonop_delay(
        struct se_cmd *cmd)
{
        if (!(cmd->se_cmd_flags & SCF_ALUA_NON_OPTIMIZED))
                return 0;
        if (in_interrupt())
                return 0;
        /*
         * The ALUA Active/NonOptimized access state delay can be disabled
         * in via configfs with a value of zero
         */
        if (!cmd->alua_nonop_delay)
                return 0;
        /*
         * struct se_cmd->alua_nonop_delay gets set by a target port group
         * defined interval in core_alua_state_nonoptimized()
         */
        msleep_interruptible(cmd->alua_nonop_delay);
        return 0;
}
EXPORT_SYMBOL(core_alua_check_nonop_delay);

static int core_alua_write_tpg_metadata(
        const char *path,
        unsigned char *md_buf,
        u32 md_buf_len)
{
        struct file *file = filp_open(path, O_RDWR | O_CREAT | O_TRUNC, 0600);
        int ret;

        if (IS_ERR(file)) {
                pr_err("filp_open(%s) for ALUA metadata failed\n", path);
                return -ENODEV;
        }
        ret = kernel_write(file, md_buf, md_buf_len, 0);
        if (ret < 0)
                pr_err("Error writing ALUA metadata file: %s\n", path);
        fput(file);
        return (ret < 0) ? -EIO : 0;
}

/*
 * Called with tg_pt_gp->tg_pt_gp_transition_mutex held
 */
static int core_alua_update_tpg_primary_metadata(
        struct t10_alua_tg_pt_gp *tg_pt_gp)
{
        unsigned char *md_buf;
        struct t10_wwn *wwn = &tg_pt_gp->tg_pt_gp_dev->t10_wwn;
        char path[ALUA_METADATA_PATH_LEN];
        int len, rc;

        md_buf = kzalloc(ALUA_MD_BUF_LEN, GFP_KERNEL);
        if (!md_buf) {
                pr_err("Unable to allocate buf for ALUA metadata\n");
                return -ENOMEM;
        }

        memset(path, 0, ALUA_METADATA_PATH_LEN);

        len = snprintf(md_buf, ALUA_MD_BUF_LEN,
                        "tg_pt_gp_id=%hu\n"
                        "alua_access_state=0x%02x\n"
                        "alua_access_status=0x%02x\n",
                        tg_pt_gp->tg_pt_gp_id,
                        tg_pt_gp->tg_pt_gp_alua_access_state,
                        tg_pt_gp->tg_pt_gp_alua_access_status);

        snprintf(path, ALUA_METADATA_PATH_LEN,
                "%s/alua/tpgs_%s/%s", db_root, &wwn->unit_serial[0],
                config_item_name(&tg_pt_gp->tg_pt_gp_group.cg_item));

        rc = core_alua_write_tpg_metadata(path, md_buf, len);
        kfree(md_buf);
        return rc;
}

static void core_alua_queue_state_change_ua(struct t10_alua_tg_pt_gp *tg_pt_gp)
{
        struct se_dev_entry *se_deve;
        struct se_lun *lun;
        struct se_lun_acl *lacl;

        spin_lock(&tg_pt_gp->tg_pt_gp_lock);
        list_for_each_entry(lun, &tg_pt_gp->tg_pt_gp_lun_list,
                                lun_tg_pt_gp_link) {
                /*
                 * After an implicit target port asymmetric access state
                 * change, a device server shall establish a unit attention
                 * condition for the initiator port associated with every I_T
                 * nexus with the additional sense code set to ASYMMETRIC
                 * ACCESS STATE CHANGED.
                 *
                 * After an explicit target port asymmetric access state
                 * change, a device server shall establish a unit attention
                 * condition with the additional sense code set to ASYMMETRIC
                 * ACCESS STATE CHANGED for the initiator port associated with
                 * every I_T nexus other than the I_T nexus on which the SET
                 * TARGET PORT GROUPS command
                 */
                if (!percpu_ref_tryget_live(&lun->lun_ref))
                        continue;
                spin_unlock(&tg_pt_gp->tg_pt_gp_lock);

                spin_lock(&lun->lun_deve_lock);
                list_for_each_entry(se_deve, &lun->lun_deve_list, lun_link) {
                        lacl = rcu_dereference_check(se_deve->se_lun_acl,
                                        lockdep_is_held(&lun->lun_deve_lock));

                        /*
                         * spc4r37 p.242:
                         * After an explicit target port asymmetric access
                         * state change, a device server shall establish a
                         * unit attention condition with the additional sense
                         * code set to ASYMMETRIC ACCESS STATE CHANGED for
                         * the initiator port associated with every I_T nexus
                         * other than the I_T nexus on which the SET TARGET
                         * PORT GROUPS command was received.
                         */
                        if ((tg_pt_gp->tg_pt_gp_alua_access_status ==
                             ALUA_STATUS_ALTERED_BY_EXPLICIT_STPG) &&
                           (tg_pt_gp->tg_pt_gp_alua_lun != NULL) &&
                            (tg_pt_gp->tg_pt_gp_alua_lun == lun))
                                continue;

                        /*
                         * se_deve->se_lun_acl pointer may be NULL for a
                         * entry created without explicit Node+MappedLUN ACLs
                         */
                        if (lacl && (tg_pt_gp->tg_pt_gp_alua_nacl != NULL) &&

                            (tg_pt_gp->tg_pt_gp_alua_nacl == lacl->se_lun_nacl))
                                continue;

                        core_scsi3_ua_allocate(se_deve, 0x2A,
                                ASCQ_2AH_ASYMMETRIC_ACCESS_STATE_CHANGED);
                }
                spin_unlock(&lun->lun_deve_lock);

                spin_lock(&tg_pt_gp->tg_pt_gp_lock);
                percpu_ref_put(&lun->lun_ref);
        }
        spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
}

static int core_alua_do_transition_tg_pt(
        struct t10_alua_tg_pt_gp *tg_pt_gp,
        int new_state,
        int explicit)
{
        int prev_state;

        mutex_lock(&tg_pt_gp->tg_pt_gp_transition_mutex);
        /* Nothing to be done here */
        if (tg_pt_gp->tg_pt_gp_alua_access_state == new_state) {
                mutex_unlock(&tg_pt_gp->tg_pt_gp_transition_mutex);
                return 0;
        }

        if (explicit && new_state == ALUA_ACCESS_STATE_TRANSITION) {
                mutex_unlock(&tg_pt_gp->tg_pt_gp_transition_mutex);
                return -EAGAIN;
        }

        /*
         * Save the old primary ALUA access state, and set the current state
         * to ALUA_ACCESS_STATE_TRANSITION.
         */
        prev_state = tg_pt_gp->tg_pt_gp_alua_access_state;
        tg_pt_gp->tg_pt_gp_alua_access_state = ALUA_ACCESS_STATE_TRANSITION;
        tg_pt_gp->tg_pt_gp_alua_access_status = (explicit) ?
                                ALUA_STATUS_ALTERED_BY_EXPLICIT_STPG :
                                ALUA_STATUS_ALTERED_BY_IMPLICIT_ALUA;

        core_alua_queue_state_change_ua(tg_pt_gp);

        if (new_state == ALUA_ACCESS_STATE_TRANSITION) {
                mutex_unlock(&tg_pt_gp->tg_pt_gp_transition_mutex);
                return 0;
        }

        /*
         * Check for the optional ALUA primary state transition delay
         */
        if (tg_pt_gp->tg_pt_gp_trans_delay_msecs != 0)
                msleep_interruptible(tg_pt_gp->tg_pt_gp_trans_delay_msecs);

        /*
         * Set the current primary ALUA access state to the requested new state
         */
        tg_pt_gp->tg_pt_gp_alua_access_state = new_state;

        /*
         * Update the ALUA metadata buf that has been allocated in
         * core_alua_do_port_transition(), this metadata will be written
         * to struct file.
         *
         * Note that there is the case where we do not want to update the
         * metadata when the saved metadata is being parsed in userspace
         * when setting the existing port access state and access status.
         *
         * Also note that the failure to write out the ALUA metadata to
         * struct file does NOT affect the actual ALUA transition.
         */
        if (tg_pt_gp->tg_pt_gp_write_metadata) {
                core_alua_update_tpg_primary_metadata(tg_pt_gp);
        }

        pr_debug("Successful %s ALUA transition TG PT Group: %s ID: %hu"
                " from primary access state %s to %s\n", (explicit) ? "explicit" :
                "implicit", config_item_name(&tg_pt_gp->tg_pt_gp_group.cg_item),
                tg_pt_gp->tg_pt_gp_id,
                core_alua_dump_state(prev_state),
                core_alua_dump_state(new_state));

        core_alua_queue_state_change_ua(tg_pt_gp);

        mutex_unlock(&tg_pt_gp->tg_pt_gp_transition_mutex);
        return 0;
}

int core_alua_do_port_transition(
        struct t10_alua_tg_pt_gp *l_tg_pt_gp,
        struct se_device *l_dev,
        struct se_lun *l_lun,
        struct se_node_acl *l_nacl,
        int new_state,
        int explicit)
{
        struct se_device *dev;
        struct t10_alua_lu_gp *lu_gp;
        struct t10_alua_lu_gp_member *lu_gp_mem, *local_lu_gp_mem;
        struct t10_alua_tg_pt_gp *tg_pt_gp;
        int primary, valid_states, rc = 0;

        if (l_dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH_ALUA)
                return -ENODEV;

        valid_states = l_tg_pt_gp->tg_pt_gp_alua_supported_states;
        if (core_alua_check_transition(new_state, valid_states, &primary,
                                       explicit) != 0)
                return -EINVAL;

        local_lu_gp_mem = l_dev->dev_alua_lu_gp_mem;
        spin_lock(&local_lu_gp_mem->lu_gp_mem_lock);
        lu_gp = local_lu_gp_mem->lu_gp;
        atomic_inc(&lu_gp->lu_gp_ref_cnt);
        spin_unlock(&local_lu_gp_mem->lu_gp_mem_lock);
        /*
         * For storage objects that are members of the 'default_lu_gp',
         * we only do transition on the passed *l_tp_pt_gp, and not
         * on all of the matching target port groups IDs in default_lu_gp.
         */
        if (!lu_gp->lu_gp_id) {
                /*
                 * core_alua_do_transition_tg_pt() will always return
                 * success.
                 */
                l_tg_pt_gp->tg_pt_gp_alua_lun = l_lun;
                l_tg_pt_gp->tg_pt_gp_alua_nacl = l_nacl;
                rc = core_alua_do_transition_tg_pt(l_tg_pt_gp,
                                                   new_state, explicit);
                atomic_dec_mb(&lu_gp->lu_gp_ref_cnt);
                return rc;
        }
        /*
         * For all other LU groups aside from 'default_lu_gp', walk all of
         * the associated storage objects looking for a matching target port
         * group ID from the local target port group.
         */
        spin_lock(&lu_gp->lu_gp_lock);
        list_for_each_entry(lu_gp_mem, &lu_gp->lu_gp_mem_list,
                                lu_gp_mem_list) {

                dev = lu_gp_mem->lu_gp_mem_dev;
                atomic_inc_mb(&lu_gp_mem->lu_gp_mem_ref_cnt);
                spin_unlock(&lu_gp->lu_gp_lock);

                spin_lock(&dev->t10_alua.tg_pt_gps_lock);
                list_for_each_entry(tg_pt_gp,
                                &dev->t10_alua.tg_pt_gps_list,
                                tg_pt_gp_list) {

                        if (!tg_pt_gp->tg_pt_gp_valid_id)
                                continue;
                        /*
                         * If the target behavior port asymmetric access state
                         * is changed for any target port group accessible via
                         * a logical unit within a LU group, the target port
                         * behavior group asymmetric access states for the same
                         * target port group accessible via other logical units
                         * in that LU group will also change.
                         */
                        if (l_tg_pt_gp->tg_pt_gp_id != tg_pt_gp->tg_pt_gp_id)
                                continue;

                        if (l_tg_pt_gp == tg_pt_gp) {
                                tg_pt_gp->tg_pt_gp_alua_lun = l_lun;
                                tg_pt_gp->tg_pt_gp_alua_nacl = l_nacl;
                        } else {
                                tg_pt_gp->tg_pt_gp_alua_lun = NULL;
                                tg_pt_gp->tg_pt_gp_alua_nacl = NULL;
                        }
                        atomic_inc_mb(&tg_pt_gp->tg_pt_gp_ref_cnt);
                        spin_unlock(&dev->t10_alua.tg_pt_gps_lock);
                        /*
                         * core_alua_do_transition_tg_pt() will always return
                         * success.
                         */
                        rc = core_alua_do_transition_tg_pt(tg_pt_gp,
                                        new_state, explicit);

                        spin_lock(&dev->t10_alua.tg_pt_gps_lock);
                        atomic_dec_mb(&tg_pt_gp->tg_pt_gp_ref_cnt);
                        if (rc)
                                break;
                }
                spin_unlock(&dev->t10_alua.tg_pt_gps_lock);

                spin_lock(&lu_gp->lu_gp_lock);
                atomic_dec_mb(&lu_gp_mem->lu_gp_mem_ref_cnt);
        }
        spin_unlock(&lu_gp->lu_gp_lock);

        if (!rc) {
                pr_debug("Successfully processed LU Group: %s all ALUA TG PT"
                         " Group IDs: %hu %s transition to primary state: %s\n",
                         config_item_name(&lu_gp->lu_gp_group.cg_item),
                         l_tg_pt_gp->tg_pt_gp_id,
                         (explicit) ? "explicit" : "implicit",
                         core_alua_dump_state(new_state));
        }

        atomic_dec_mb(&lu_gp->lu_gp_ref_cnt);
        return rc;
}

static int core_alua_update_tpg_secondary_metadata(struct se_lun *lun)
{
        struct se_portal_group *se_tpg = lun->lun_tpg;
        unsigned char *md_buf;
        char path[ALUA_METADATA_PATH_LEN], wwn[ALUA_SECONDARY_METADATA_WWN_LEN];
        int len, rc;

        mutex_lock(&lun->lun_tg_pt_md_mutex);

        md_buf = kzalloc(ALUA_MD_BUF_LEN, GFP_KERNEL);
        if (!md_buf) {
                pr_err("Unable to allocate buf for ALUA metadata\n");
                rc = -ENOMEM;
                goto out_unlock;
        }

        memset(path, 0, ALUA_METADATA_PATH_LEN);
        memset(wwn, 0, ALUA_SECONDARY_METADATA_WWN_LEN);

        len = snprintf(wwn, ALUA_SECONDARY_METADATA_WWN_LEN, "%s",
                        se_tpg->se_tpg_tfo->tpg_get_wwn(se_tpg));

        if (se_tpg->se_tpg_tfo->tpg_get_tag != NULL)
                snprintf(wwn+len, ALUA_SECONDARY_METADATA_WWN_LEN-len, "+%hu",
                                se_tpg->se_tpg_tfo->tpg_get_tag(se_tpg));

        len = snprintf(md_buf, ALUA_MD_BUF_LEN, "alua_tg_pt_offline=%d\n"
                        "alua_tg_pt_status=0x%02x\n",
                        atomic_read(&lun->lun_tg_pt_secondary_offline),
                        lun->lun_tg_pt_secondary_stat);

        snprintf(path, ALUA_METADATA_PATH_LEN, "%s/alua/%s/%s/lun_%llu",
                        db_root, se_tpg->se_tpg_tfo->get_fabric_name(), wwn,
                        lun->unpacked_lun);

        rc = core_alua_write_tpg_metadata(path, md_buf, len);
        kfree(md_buf);

out_unlock:
        mutex_unlock(&lun->lun_tg_pt_md_mutex);
        return rc;
}

static int core_alua_set_tg_pt_secondary_state(
        struct se_lun *lun,
        int explicit,
        int offline)
{
        struct t10_alua_tg_pt_gp *tg_pt_gp;
        int trans_delay_msecs;

        spin_lock(&lun->lun_tg_pt_gp_lock);
        tg_pt_gp = lun->lun_tg_pt_gp;
        if (!tg_pt_gp) {
                spin_unlock(&lun->lun_tg_pt_gp_lock);
                pr_err("Unable to complete secondary state"
                                " transition\n");
                return -EINVAL;
        }
        trans_delay_msecs = tg_pt_gp->tg_pt_gp_trans_delay_msecs;
        /*
         * Set the secondary ALUA target port access state to OFFLINE
         * or release the previously secondary state for struct se_lun
         */
        if (offline)
                atomic_set(&lun->lun_tg_pt_secondary_offline, 1);
        else
                atomic_set(&lun->lun_tg_pt_secondary_offline, 0);

        lun->lun_tg_pt_secondary_stat = (explicit) ?
                        ALUA_STATUS_ALTERED_BY_EXPLICIT_STPG :
                        ALUA_STATUS_ALTERED_BY_IMPLICIT_ALUA;

        pr_debug("Successful %s ALUA transition TG PT Group: %s ID: %hu"
                " to secondary access state: %s\n", (explicit) ? "explicit" :
                "implicit", config_item_name(&tg_pt_gp->tg_pt_gp_group.cg_item),
                tg_pt_gp->tg_pt_gp_id, (offline) ? "OFFLINE" : "ONLINE");

        spin_unlock(&lun->lun_tg_pt_gp_lock);
        /*
         * Do the optional transition delay after we set the secondary
         * ALUA access state.
         */
        if (trans_delay_msecs != 0)
                msleep_interruptible(trans_delay_msecs);
        /*
         * See if we need to update the ALUA fabric port metadata for
         * secondary state and status
         */
        if (lun->lun_tg_pt_secondary_write_md)
                core_alua_update_tpg_secondary_metadata(lun);

        return 0;
}

struct t10_alua_lba_map *
core_alua_allocate_lba_map(struct list_head *list,
                           u64 first_lba, u64 last_lba)
{
        struct t10_alua_lba_map *lba_map;

        lba_map = kmem_cache_zalloc(t10_alua_lba_map_cache, GFP_KERNEL);
        if (!lba_map) {
                pr_err("Unable to allocate struct t10_alua_lba_map\n");
                return ERR_PTR(-ENOMEM);
        }
        INIT_LIST_HEAD(&lba_map->lba_map_mem_list);
        lba_map->lba_map_first_lba = first_lba;
        lba_map->lba_map_last_lba = last_lba;

        list_add_tail(&lba_map->lba_map_list, list);
        return lba_map;
}

int
core_alua_allocate_lba_map_mem(struct t10_alua_lba_map *lba_map,
                               int pg_id, int state)
{
        struct t10_alua_lba_map_member *lba_map_mem;

        list_for_each_entry(lba_map_mem, &lba_map->lba_map_mem_list,
                            lba_map_mem_list) {
                if (lba_map_mem->lba_map_mem_alua_pg_id == pg_id) {
                        pr_err("Duplicate pg_id %d in lba_map\n", pg_id);
                        return -EINVAL;
                }
        }

        lba_map_mem = kmem_cache_zalloc(t10_alua_lba_map_mem_cache, GFP_KERNEL);
        if (!lba_map_mem) {
                pr_err("Unable to allocate struct t10_alua_lba_map_mem\n");
                return -ENOMEM;
        }
        lba_map_mem->lba_map_mem_alua_state = state;
        lba_map_mem->lba_map_mem_alua_pg_id = pg_id;

        list_add_tail(&lba_map_mem->lba_map_mem_list,
                      &lba_map->lba_map_mem_list);
        return 0;
}

void
core_alua_free_lba_map(struct list_head *lba_list)
{
        struct t10_alua_lba_map *lba_map, *lba_map_tmp;
        struct t10_alua_lba_map_member *lba_map_mem, *lba_map_mem_tmp;

        list_for_each_entry_safe(lba_map, lba_map_tmp, lba_list,
                                 lba_map_list) {
                list_for_each_entry_safe(lba_map_mem, lba_map_mem_tmp,
                                         &lba_map->lba_map_mem_list,
                                         lba_map_mem_list) {
                        list_del(&lba_map_mem->lba_map_mem_list);
                        kmem_cache_free(t10_alua_lba_map_mem_cache,
                                        lba_map_mem);
                }
                list_del(&lba_map->lba_map_list);
                kmem_cache_free(t10_alua_lba_map_cache, lba_map);
        }
}

void
core_alua_set_lba_map(struct se_device *dev, struct list_head *lba_map_list,
                      int segment_size, int segment_mult)
{
        struct list_head old_lba_map_list;
        struct t10_alua_tg_pt_gp *tg_pt_gp;
        int activate = 0, supported;

        INIT_LIST_HEAD(&old_lba_map_list);
        spin_lock(&dev->t10_alua.lba_map_lock);
        dev->t10_alua.lba_map_segment_size = segment_size;
        dev->t10_alua.lba_map_segment_multiplier = segment_mult;
        list_splice_init(&dev->t10_alua.lba_map_list, &old_lba_map_list);
        if (lba_map_list) {
                list_splice_init(lba_map_list, &dev->t10_alua.lba_map_list);
                activate = 1;
        }
        spin_unlock(&dev->t10_alua.lba_map_lock);
        spin_lock(&dev->t10_alua.tg_pt_gps_lock);
        list_for_each_entry(tg_pt_gp, &dev->t10_alua.tg_pt_gps_list,
                            tg_pt_gp_list) {

                if (!tg_pt_gp->tg_pt_gp_valid_id)
                        continue;
                supported = tg_pt_gp->tg_pt_gp_alua_supported_states;
                if (activate)
                        supported |= ALUA_LBD_SUP;
                else
                        supported &= ~ALUA_LBD_SUP;
                tg_pt_gp->tg_pt_gp_alua_supported_states = supported;
        }
        spin_unlock(&dev->t10_alua.tg_pt_gps_lock);
        core_alua_free_lba_map(&old_lba_map_list);
}

struct t10_alua_lu_gp *
core_alua_allocate_lu_gp(const char *name, int def_group)
{
        struct t10_alua_lu_gp *lu_gp;

        lu_gp = kmem_cache_zalloc(t10_alua_lu_gp_cache, GFP_KERNEL);
        if (!lu_gp) {
                pr_err("Unable to allocate struct t10_alua_lu_gp\n");
                return ERR_PTR(-ENOMEM);
        }
        INIT_LIST_HEAD(&lu_gp->lu_gp_node);
        INIT_LIST_HEAD(&lu_gp->lu_gp_mem_list);
        spin_lock_init(&lu_gp->lu_gp_lock);
        atomic_set(&lu_gp->lu_gp_ref_cnt, 0);

        if (def_group) {
                lu_gp->lu_gp_id = alua_lu_gps_counter++;
                lu_gp->lu_gp_valid_id = 1;
                alua_lu_gps_count++;
        }

        return lu_gp;
}

int core_alua_set_lu_gp_id(struct t10_alua_lu_gp *lu_gp, u16 lu_gp_id)
{
        struct t10_alua_lu_gp *lu_gp_tmp;
        u16 lu_gp_id_tmp;
        /*
         * The lu_gp->lu_gp_id may only be set once..
         */
        if (lu_gp->lu_gp_valid_id) {
                pr_warn("ALUA LU Group already has a valid ID,"
                        " ignoring request\n");
                return -EINVAL;
        }

        spin_lock(&lu_gps_lock);
        if (alua_lu_gps_count == 0x0000ffff) {
                pr_err("Maximum ALUA alua_lu_gps_count:"
                                " 0x0000ffff reached\n");
                spin_unlock(&lu_gps_lock);
                kmem_cache_free(t10_alua_lu_gp_cache, lu_gp);
                return -ENOSPC;
        }
again:
        lu_gp_id_tmp = (lu_gp_id != 0) ? lu_gp_id :
                                alua_lu_gps_counter++;

        list_for_each_entry(lu_gp_tmp, &lu_gps_list, lu_gp_node) {
                if (lu_gp_tmp->lu_gp_id == lu_gp_id_tmp) {
                        if (!lu_gp_id)
                                goto again;

                        pr_warn("ALUA Logical Unit Group ID: %hu"
                                " already exists, ignoring request\n",
                                lu_gp_id);
                        spin_unlock(&lu_gps_lock);
                        return -EINVAL;
                }
        }

        lu_gp->lu_gp_id = lu_gp_id_tmp;
        lu_gp->lu_gp_valid_id = 1;
        list_add_tail(&lu_gp->lu_gp_node, &lu_gps_list);
        alua_lu_gps_count++;
        spin_unlock(&lu_gps_lock);

        return 0;
}

static struct t10_alua_lu_gp_member *
core_alua_allocate_lu_gp_mem(struct se_device *dev)
{
        struct t10_alua_lu_gp_member *lu_gp_mem;

        lu_gp_mem = kmem_cache_zalloc(t10_alua_lu_gp_mem_cache, GFP_KERNEL);
        if (!lu_gp_mem) {
                pr_err("Unable to allocate struct t10_alua_lu_gp_member\n");
                return ERR_PTR(-ENOMEM);
        }
        INIT_LIST_HEAD(&lu_gp_mem->lu_gp_mem_list);
        spin_lock_init(&lu_gp_mem->lu_gp_mem_lock);
        atomic_set(&lu_gp_mem->lu_gp_mem_ref_cnt, 0);

        lu_gp_mem->lu_gp_mem_dev = dev;
        dev->dev_alua_lu_gp_mem = lu_gp_mem;

        return lu_gp_mem;
}

void core_alua_free_lu_gp(struct t10_alua_lu_gp *lu_gp)
{
        struct t10_alua_lu_gp_member *lu_gp_mem, *lu_gp_mem_tmp;
        /*
         * Once we have reached this point, config_item_put() has
         * already been called from target_core_alua_drop_lu_gp().
         *
         * Here, we remove the *lu_gp from the global list so that
         * no associations can be made while we are releasing
         * struct t10_alua_lu_gp.
         */
        spin_lock(&lu_gps_lock);
        list_del(&lu_gp->lu_gp_node);
        alua_lu_gps_count--;
        spin_unlock(&lu_gps_lock);
        /*
         * Allow struct t10_alua_lu_gp * referenced by core_alua_get_lu_gp_by_name()
         * in target_core_configfs.c:target_core_store_alua_lu_gp() to be
         * released with core_alua_put_lu_gp_from_name()
         */
        while (atomic_read(&lu_gp->lu_gp_ref_cnt))
                cpu_relax();
        /*
         * Release reference to struct t10_alua_lu_gp * from all associated
         * struct se_device.
         */
        spin_lock(&lu_gp->lu_gp_lock);
        list_for_each_entry_safe(lu_gp_mem, lu_gp_mem_tmp,
                                &lu_gp->lu_gp_mem_list, lu_gp_mem_list) {
                if (lu_gp_mem->lu_gp_assoc) {
                        list_del(&lu_gp_mem->lu_gp_mem_list);
                        lu_gp->lu_gp_members--;
                        lu_gp_mem->lu_gp_assoc = 0;
                }
                spin_unlock(&lu_gp->lu_gp_lock);
                /*
                 *
                 * lu_gp_mem is associated with a single
                 * struct se_device->dev_alua_lu_gp_mem, and is released when
                 * struct se_device is released via core_alua_free_lu_gp_mem().
                 *
                 * If the passed lu_gp does NOT match the default_lu_gp, assume
                 * we want to re-associate a given lu_gp_mem with default_lu_gp.
                 */
                spin_lock(&lu_gp_mem->lu_gp_mem_lock);
                if (lu_gp != default_lu_gp)
                        __core_alua_attach_lu_gp_mem(lu_gp_mem,
                                        default_lu_gp);
                else
                        lu_gp_mem->lu_gp = NULL;
                spin_unlock(&lu_gp_mem->lu_gp_mem_lock);

                spin_lock(&lu_gp->lu_gp_lock);
        }
        spin_unlock(&lu_gp->lu_gp_lock);

        kmem_cache_free(t10_alua_lu_gp_cache, lu_gp);
}

void core_alua_free_lu_gp_mem(struct se_device *dev)
{
        struct t10_alua_lu_gp *lu_gp;
        struct t10_alua_lu_gp_member *lu_gp_mem;

        lu_gp_mem = dev->dev_alua_lu_gp_mem;
        if (!lu_gp_mem)
                return;

        while (atomic_read(&lu_gp_mem->lu_gp_mem_ref_cnt))
                cpu_relax();

        spin_lock(&lu_gp_mem->lu_gp_mem_lock);
        lu_gp = lu_gp_mem->lu_gp;
        if (lu_gp) {
                spin_lock(&lu_gp->lu_gp_lock);
                if (lu_gp_mem->lu_gp_assoc) {
                        list_del(&lu_gp_mem->lu_gp_mem_list);
                        lu_gp->lu_gp_members--;
                        lu_gp_mem->lu_gp_assoc = 0;
                }
                spin_unlock(&lu_gp->lu_gp_lock);
                lu_gp_mem->lu_gp = NULL;
        }
        spin_unlock(&lu_gp_mem->lu_gp_mem_lock);

        kmem_cache_free(t10_alua_lu_gp_mem_cache, lu_gp_mem);
}

struct t10_alua_lu_gp *core_alua_get_lu_gp_by_name(const char *name)
{
        struct t10_alua_lu_gp *lu_gp;
        struct config_item *ci;

        spin_lock(&lu_gps_lock);
        list_for_each_entry(lu_gp, &lu_gps_list, lu_gp_node) {
                if (!lu_gp->lu_gp_valid_id)
                        continue;
                ci = &lu_gp->lu_gp_group.cg_item;
                if (!strcmp(config_item_name(ci), name)) {
                        atomic_inc(&lu_gp->lu_gp_ref_cnt);
                        spin_unlock(&lu_gps_lock);
                        return lu_gp;
                }
        }
        spin_unlock(&lu_gps_lock);

        return NULL;
}

void core_alua_put_lu_gp_from_name(struct t10_alua_lu_gp *lu_gp)
{
        spin_lock(&lu_gps_lock);
        atomic_dec(&lu_gp->lu_gp_ref_cnt);
        spin_unlock(&lu_gps_lock);
}

/*
 * Called with struct t10_alua_lu_gp_member->lu_gp_mem_lock
 */
void __core_alua_attach_lu_gp_mem(
        struct t10_alua_lu_gp_member *lu_gp_mem,
        struct t10_alua_lu_gp *lu_gp)
{
        spin_lock(&lu_gp->lu_gp_lock);
        lu_gp_mem->lu_gp = lu_gp;
        lu_gp_mem->lu_gp_assoc = 1;
        list_add_tail(&lu_gp_mem->lu_gp_mem_list, &lu_gp->lu_gp_mem_list);
        lu_gp->lu_gp_members++;
        spin_unlock(&lu_gp->lu_gp_lock);
}

/*
 * Called with struct t10_alua_lu_gp_member->lu_gp_mem_lock
 */
void __core_alua_drop_lu_gp_mem(
        struct t10_alua_lu_gp_member *lu_gp_mem,
        struct t10_alua_lu_gp *lu_gp)
{
        spin_lock(&lu_gp->lu_gp_lock);
        list_del(&lu_gp_mem->lu_gp_mem_list);
        lu_gp_mem->lu_gp = NULL;
        lu_gp_mem->lu_gp_assoc = 0;
        lu_gp->lu_gp_members--;
        spin_unlock(&lu_gp->lu_gp_lock);
}

struct t10_alua_tg_pt_gp *core_alua_allocate_tg_pt_gp(struct se_device *dev,
                const char *name, int def_group)
{
        struct t10_alua_tg_pt_gp *tg_pt_gp;

        tg_pt_gp = kmem_cache_zalloc(t10_alua_tg_pt_gp_cache, GFP_KERNEL);
        if (!tg_pt_gp) {
                pr_err("Unable to allocate struct t10_alua_tg_pt_gp\n");
                return NULL;
        }
        INIT_LIST_HEAD(&tg_pt_gp->tg_pt_gp_list);
        INIT_LIST_HEAD(&tg_pt_gp->tg_pt_gp_lun_list);
        mutex_init(&tg_pt_gp->tg_pt_gp_transition_mutex);
        spin_lock_init(&tg_pt_gp->tg_pt_gp_lock);
        atomic_set(&tg_pt_gp->tg_pt_gp_ref_cnt, 0);
        tg_pt_gp->tg_pt_gp_dev = dev;
        tg_pt_gp->tg_pt_gp_alua_access_state =
                        ALUA_ACCESS_STATE_ACTIVE_OPTIMIZED;
        /*
         * Enable both explicit and implicit ALUA support by default
         */
        tg_pt_gp->tg_pt_gp_alua_access_type =
                        TPGS_EXPLICIT_ALUA | TPGS_IMPLICIT_ALUA;
        /*
         * Set the default Active/NonOptimized Delay in milliseconds
         */
        tg_pt_gp->tg_pt_gp_nonop_delay_msecs = ALUA_DEFAULT_NONOP_DELAY_MSECS;
        tg_pt_gp->tg_pt_gp_trans_delay_msecs = ALUA_DEFAULT_TRANS_DELAY_MSECS;
        tg_pt_gp->tg_pt_gp_implicit_trans_secs = ALUA_DEFAULT_IMPLICIT_TRANS_SECS;

        /*
         * Enable all supported states
         */
        tg_pt_gp->tg_pt_gp_alua_supported_states =
            ALUA_T_SUP | ALUA_O_SUP |
            ALUA_U_SUP | ALUA_S_SUP | ALUA_AN_SUP | ALUA_AO_SUP;

        if (def_group) {
                spin_lock(&dev->t10_alua.tg_pt_gps_lock);
                tg_pt_gp->tg_pt_gp_id =
                                dev->t10_alua.alua_tg_pt_gps_counter++;
                tg_pt_gp->tg_pt_gp_valid_id = 1;
                dev->t10_alua.alua_tg_pt_gps_count++;
                list_add_tail(&tg_pt_gp->tg_pt_gp_list,
                              &dev->t10_alua.tg_pt_gps_list);
                spin_unlock(&dev->t10_alua.tg_pt_gps_lock);
        }

        return tg_pt_gp;
}

int core_alua_set_tg_pt_gp_id(
        struct t10_alua_tg_pt_gp *tg_pt_gp,
        u16 tg_pt_gp_id)
{
        struct se_device *dev = tg_pt_gp->tg_pt_gp_dev;
        struct t10_alua_tg_pt_gp *tg_pt_gp_tmp;
        u16 tg_pt_gp_id_tmp;

        /*
         * The tg_pt_gp->tg_pt_gp_id may only be set once..
         */
        if (tg_pt_gp->tg_pt_gp_valid_id) {
                pr_warn("ALUA TG PT Group already has a valid ID,"
                        " ignoring request\n");
                return -EINVAL;
        }

        spin_lock(&dev->t10_alua.tg_pt_gps_lock);
        if (dev->t10_alua.alua_tg_pt_gps_count == 0x0000ffff) {
                pr_err("Maximum ALUA alua_tg_pt_gps_count:"
                        " 0x0000ffff reached\n");
                spin_unlock(&dev->t10_alua.tg_pt_gps_lock);
                kmem_cache_free(t10_alua_tg_pt_gp_cache, tg_pt_gp);
                return -ENOSPC;
        }
again:
        tg_pt_gp_id_tmp = (tg_pt_gp_id != 0) ? tg_pt_gp_id :
                        dev->t10_alua.alua_tg_pt_gps_counter++;

        list_for_each_entry(tg_pt_gp_tmp, &dev->t10_alua.tg_pt_gps_list,
                        tg_pt_gp_list) {
                if (tg_pt_gp_tmp->tg_pt_gp_id == tg_pt_gp_id_tmp) {
                        if (!tg_pt_gp_id)
                                goto again;

                        pr_err("ALUA Target Port Group ID: %hu already"
                                " exists, ignoring request\n", tg_pt_gp_id);
                        spin_unlock(&dev->t10_alua.tg_pt_gps_lock);
                        return -EINVAL;
                }
        }

        tg_pt_gp->tg_pt_gp_id = tg_pt_gp_id_tmp;
        tg_pt_gp->tg_pt_gp_valid_id = 1;
        list_add_tail(&tg_pt_gp->tg_pt_gp_list,
                        &dev->t10_alua.tg_pt_gps_list);
        dev->t10_alua.alua_tg_pt_gps_count++;
        spin_unlock(&dev->t10_alua.tg_pt_gps_lock);

        return 0;
}

void core_alua_free_tg_pt_gp(
        struct t10_alua_tg_pt_gp *tg_pt_gp)
{
        struct se_device *dev = tg_pt_gp->tg_pt_gp_dev;
        struct se_lun *lun, *next;

        /*
         * Once we have reached this point, config_item_put() has already
         * been called from target_core_alua_drop_tg_pt_gp().
         *
         * Here we remove *tg_pt_gp from the global list so that
         * no associations *OR* explicit ALUA via SET_TARGET_PORT_GROUPS
         * can be made while we are releasing struct t10_alua_tg_pt_gp.
         */
        spin_lock(&dev->t10_alua.tg_pt_gps_lock);
        list_del(&tg_pt_gp->tg_pt_gp_list);
        dev->t10_alua.alua_tg_pt_gps_counter--;
        spin_unlock(&dev->t10_alua.tg_pt_gps_lock);

        /*
         * Allow a struct t10_alua_tg_pt_gp_member * referenced by
         * core_alua_get_tg_pt_gp_by_name() in
         * target_core_configfs.c:target_core_store_alua_tg_pt_gp()
         * to be released with core_alua_put_tg_pt_gp_from_name().
         */
        while (atomic_read(&tg_pt_gp->tg_pt_gp_ref_cnt))
                cpu_relax();

        /*
         * Release reference to struct t10_alua_tg_pt_gp from all associated
         * struct se_port.
         */
        spin_lock(&tg_pt_gp->tg_pt_gp_lock);
        list_for_each_entry_safe(lun, next,
                        &tg_pt_gp->tg_pt_gp_lun_list, lun_tg_pt_gp_link) {
                list_del_init(&lun->lun_tg_pt_gp_link);
                tg_pt_gp->tg_pt_gp_members--;

                spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
                /*
                 * If the passed tg_pt_gp does NOT match the default_tg_pt_gp,
                 * assume we want to re-associate a given tg_pt_gp_mem with
                 * default_tg_pt_gp.
                 */
                spin_lock(&lun->lun_tg_pt_gp_lock);
                if (tg_pt_gp != dev->t10_alua.default_tg_pt_gp) {
                        __target_attach_tg_pt_gp(lun,
                                        dev->t10_alua.default_tg_pt_gp);
                } else
                        lun->lun_tg_pt_gp = NULL;
                spin_unlock(&lun->lun_tg_pt_gp_lock);

                spin_lock(&tg_pt_gp->tg_pt_gp_lock);
        }
        spin_unlock(&tg_pt_gp->tg_pt_gp_lock);

        kmem_cache_free(t10_alua_tg_pt_gp_cache, tg_pt_gp);
}

static struct t10_alua_tg_pt_gp *core_alua_get_tg_pt_gp_by_name(
                struct se_device *dev, const char *name)
{
        struct t10_alua_tg_pt_gp *tg_pt_gp;
        struct config_item *ci;

        spin_lock(&dev->t10_alua.tg_pt_gps_lock);
        list_for_each_entry(tg_pt_gp, &dev->t10_alua.tg_pt_gps_list,
                        tg_pt_gp_list) {
                if (!tg_pt_gp->tg_pt_gp_valid_id)
                        continue;
                ci = &tg_pt_gp->tg_pt_gp_group.cg_item;
                if (!strcmp(config_item_name(ci), name)) {
                        atomic_inc(&tg_pt_gp->tg_pt_gp_ref_cnt);
                        spin_unlock(&dev->t10_alua.tg_pt_gps_lock);
                        return tg_pt_gp;
                }
        }
        spin_unlock(&dev->t10_alua.tg_pt_gps_lock);

        return NULL;
}

static void core_alua_put_tg_pt_gp_from_name(
        struct t10_alua_tg_pt_gp *tg_pt_gp)
{
        struct se_device *dev = tg_pt_gp->tg_pt_gp_dev;

        spin_lock(&dev->t10_alua.tg_pt_gps_lock);
        atomic_dec(&tg_pt_gp->tg_pt_gp_ref_cnt);
        spin_unlock(&dev->t10_alua.tg_pt_gps_lock);
}

static void __target_attach_tg_pt_gp(struct se_lun *lun,
                struct t10_alua_tg_pt_gp *tg_pt_gp)
{
        struct se_dev_entry *se_deve;

        assert_spin_locked(&lun->lun_tg_pt_gp_lock);

        spin_lock(&tg_pt_gp->tg_pt_gp_lock);
        lun->lun_tg_pt_gp = tg_pt_gp;
        list_add_tail(&lun->lun_tg_pt_gp_link, &tg_pt_gp->tg_pt_gp_lun_list);
        tg_pt_gp->tg_pt_gp_members++;
        spin_lock(&lun->lun_deve_lock);
        list_for_each_entry(se_deve, &lun->lun_deve_list, lun_link)
                core_scsi3_ua_allocate(se_deve, 0x3f,
                                       ASCQ_3FH_INQUIRY_DATA_HAS_CHANGED);
        spin_unlock(&lun->lun_deve_lock);
        spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
}

void target_attach_tg_pt_gp(struct se_lun *lun,
                struct t10_alua_tg_pt_gp *tg_pt_gp)
{
        spin_lock(&lun->lun_tg_pt_gp_lock);
        __target_attach_tg_pt_gp(lun, tg_pt_gp);
        spin_unlock(&lun->lun_tg_pt_gp_lock);
}

static void __target_detach_tg_pt_gp(struct se_lun *lun,
                struct t10_alua_tg_pt_gp *tg_pt_gp)
{
        assert_spin_locked(&lun->lun_tg_pt_gp_lock);

        spin_lock(&tg_pt_gp->tg_pt_gp_lock);
        list_del_init(&lun->lun_tg_pt_gp_link);
        tg_pt_gp->tg_pt_gp_members--;
        spin_unlock(&tg_pt_gp->tg_pt_gp_lock);

        lun->lun_tg_pt_gp = NULL;
}

void target_detach_tg_pt_gp(struct se_lun *lun)
{
        struct t10_alua_tg_pt_gp *tg_pt_gp;

        spin_lock(&lun->lun_tg_pt_gp_lock);
        tg_pt_gp = lun->lun_tg_pt_gp;
        if (tg_pt_gp)
                __target_detach_tg_pt_gp(lun, tg_pt_gp);
        spin_unlock(&lun->lun_tg_pt_gp_lock);
}

ssize_t core_alua_show_tg_pt_gp_info(struct se_lun *lun, char *page)
{
        struct config_item *tg_pt_ci;
        struct t10_alua_tg_pt_gp *tg_pt_gp;
        ssize_t len = 0;

        spin_lock(&lun->lun_tg_pt_gp_lock);
        tg_pt_gp = lun->lun_tg_pt_gp;
        if (tg_pt_gp) {
                tg_pt_ci = &tg_pt_gp->tg_pt_gp_group.cg_item;
                len += sprintf(page, "TG Port Alias: %s\nTG Port Group ID:"
                        " %hu\nTG Port Primary Access State: %s\nTG Port "
                        "Primary Access Status: %s\nTG Port Secondary Access"
                        " State: %s\nTG Port Secondary Access Status: %s\n",
                        config_item_name(tg_pt_ci), tg_pt_gp->tg_pt_gp_id,
                        core_alua_dump_state(
                                tg_pt_gp->tg_pt_gp_alua_access_state),
                        core_alua_dump_status(
                                tg_pt_gp->tg_pt_gp_alua_access_status),
                        atomic_read(&lun->lun_tg_pt_secondary_offline) ?
                        "Offline" : "None",
                        core_alua_dump_status(lun->lun_tg_pt_secondary_stat));
        }
        spin_unlock(&lun->lun_tg_pt_gp_lock);

        return len;
}

ssize_t core_alua_store_tg_pt_gp_info(
        struct se_lun *lun,
        const char *page,
        size_t count)
{
        struct se_portal_group *tpg = lun->lun_tpg;
        /*
         * rcu_dereference_raw protected by se_lun->lun_group symlink
         * reference to se_device->dev_group.
         */
        struct se_device *dev = rcu_dereference_raw(lun->lun_se_dev);
        struct t10_alua_tg_pt_gp *tg_pt_gp = NULL, *tg_pt_gp_new = NULL;
        unsigned char buf[TG_PT_GROUP_NAME_BUF];
        int move = 0;

        if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH_ALUA ||
            (dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE))
                return -ENODEV;

        if (count > TG_PT_GROUP_NAME_BUF) {
                pr_err("ALUA Target Port Group alias too large!\n");
                return -EINVAL;
        }
        memset(buf, 0, TG_PT_GROUP_NAME_BUF);
        memcpy(buf, page, count);
        /*
         * Any ALUA target port group alias besides "NULL" means we will be
         * making a new group association.
         */
        if (strcmp(strstrip(buf), "NULL")) {
                /*
                 * core_alua_get_tg_pt_gp_by_name() will increment reference to
                 * struct t10_alua_tg_pt_gp.  This reference is released with
                 * core_alua_put_tg_pt_gp_from_name() below.
                 */
                tg_pt_gp_new = core_alua_get_tg_pt_gp_by_name(dev,
                                        strstrip(buf));
                if (!tg_pt_gp_new)
                        return -ENODEV;
        }

        spin_lock(&lun->lun_tg_pt_gp_lock);
        tg_pt_gp = lun->lun_tg_pt_gp;
        if (tg_pt_gp) {
                /*
                 * Clearing an existing tg_pt_gp association, and replacing
                 * with the default_tg_pt_gp.
                 */
                if (!tg_pt_gp_new) {
                        pr_debug("Target_Core_ConfigFS: Moving"
                                " %s/tpgt_%hu/%s from ALUA Target Port Group:"
                                " alua/%s, ID: %hu back to"
                                " default_tg_pt_gp\n",
                                tpg->se_tpg_tfo->tpg_get_wwn(tpg),
                                tpg->se_tpg_tfo->tpg_get_tag(tpg),
                                config_item_name(&lun->lun_group.cg_item),
                                config_item_name(
                                        &tg_pt_gp->tg_pt_gp_group.cg_item),
                                tg_pt_gp->tg_pt_gp_id);

                        __target_detach_tg_pt_gp(lun, tg_pt_gp);
                        __target_attach_tg_pt_gp(lun,
                                        dev->t10_alua.default_tg_pt_gp);
                        spin_unlock(&lun->lun_tg_pt_gp_lock);

                        return count;
                }
                __target_detach_tg_pt_gp(lun, tg_pt_gp);
                move = 1;
        }

        __target_attach_tg_pt_gp(lun, tg_pt_gp_new);
        spin_unlock(&lun->lun_tg_pt_gp_lock);
        pr_debug("Target_Core_ConfigFS: %s %s/tpgt_%hu/%s to ALUA"
                " Target Port Group: alua/%s, ID: %hu\n", (move) ?
                "Moving" : "Adding", tpg->se_tpg_tfo->tpg_get_wwn(tpg),
                tpg->se_tpg_tfo->tpg_get_tag(tpg),
                config_item_name(&lun->lun_group.cg_item),
                config_item_name(&tg_pt_gp_new->tg_pt_gp_group.cg_item),
                tg_pt_gp_new->tg_pt_gp_id);

        core_alua_put_tg_pt_gp_from_name(tg_pt_gp_new);
        return count;
}

ssize_t core_alua_show_access_type(
        struct t10_alua_tg_pt_gp *tg_pt_gp,

        char *page)
{
        if ((tg_pt_gp->tg_pt_gp_alua_access_type & TPGS_EXPLICIT_ALUA) &&
            (tg_pt_gp->tg_pt_gp_alua_access_type & TPGS_IMPLICIT_ALUA))
                return sprintf(page, "Implicit and Explicit\n");
        else if (tg_pt_gp->tg_pt_gp_alua_access_type & TPGS_IMPLICIT_ALUA)
                return sprintf(page, "Implicit\n");
        else if (tg_pt_gp->tg_pt_gp_alua_access_type & TPGS_EXPLICIT_ALUA)
                return sprintf(page, "Explicit\n");
        else
                return sprintf(page, "None\n");
}

ssize_t core_alua_store_access_type(
        struct t10_alua_tg_pt_gp *tg_pt_gp,
        const char *page,
        size_t count)
{
        unsigned long tmp;
        int ret;

        ret = kstrtoul(page, 0, &tmp);
        if (ret < 0) {
                pr_err("Unable to extract alua_access_type\n");
                return ret;
        }
        if ((tmp != 0) && (tmp != 1) && (tmp != 2) && (tmp != 3)) {
                pr_err("Illegal value for alua_access_type:"
                                " %lu\n", tmp);
                return -EINVAL;
        }
        if (tmp == 3)
                tg_pt_gp->tg_pt_gp_alua_access_type =
                        TPGS_IMPLICIT_ALUA | TPGS_EXPLICIT_ALUA;
        else if (tmp == 2)
                tg_pt_gp->tg_pt_gp_alua_access_type = TPGS_EXPLICIT_ALUA;
        else if (tmp == 1)
                tg_pt_gp->tg_pt_gp_alua_access_type = TPGS_IMPLICIT_ALUA;
        else
                tg_pt_gp->tg_pt_gp_alua_access_type = 0;

        return count;
}

ssize_t core_alua_show_nonop_delay_msecs(
        struct t10_alua_tg_pt_gp *tg_pt_gp,
        char *page)
{
        return sprintf(page, "%d\n", tg_pt_gp->tg_pt_gp_nonop_delay_msecs);
}

ssize_t core_alua_store_nonop_delay_msecs(
        struct t10_alua_tg_pt_gp *tg_pt_gp,
        const char *page,
        size_t count)
{
        unsigned long tmp;
        int ret;

        ret = kstrtoul(page, 0, &tmp);
        if (ret < 0) {
                pr_err("Unable to extract nonop_delay_msecs\n");
                return ret;
        }
        if (tmp > ALUA_MAX_NONOP_DELAY_MSECS) {
                pr_err("Passed nonop_delay_msecs: %lu, exceeds"
                        " ALUA_MAX_NONOP_DELAY_MSECS: %d\n", tmp,
                        ALUA_MAX_NONOP_DELAY_MSECS);
                return -EINVAL;
        }
        tg_pt_gp->tg_pt_gp_nonop_delay_msecs = (int)tmp;

        return count;
}

ssize_t core_alua_show_trans_delay_msecs(
        struct t10_alua_tg_pt_gp *tg_pt_gp,
        char *page)
{
        return sprintf(page, "%d\n", tg_pt_gp->tg_pt_gp_trans_delay_msecs);
}

ssize_t core_alua_store_trans_delay_msecs(
        struct t10_alua_tg_pt_gp *tg_pt_gp,
        const char *page,
        size_t count)
{
        unsigned long tmp;
        int ret;

        ret = kstrtoul(page, 0, &tmp);
        if (ret < 0) {
                pr_err("Unable to extract trans_delay_msecs\n");
                return ret;
        }
        if (tmp > ALUA_MAX_TRANS_DELAY_MSECS) {
                pr_err("Passed trans_delay_msecs: %lu, exceeds"
                        " ALUA_MAX_TRANS_DELAY_MSECS: %d\n", tmp,
                        ALUA_MAX_TRANS_DELAY_MSECS);
                return -EINVAL;
        }
        tg_pt_gp->tg_pt_gp_trans_delay_msecs = (int)tmp;

        return count;
}

ssize_t core_alua_show_implicit_trans_secs(
        struct t10_alua_tg_pt_gp *tg_pt_gp,
        char *page)
{
        return sprintf(page, "%d\n", tg_pt_gp->tg_pt_gp_implicit_trans_secs);
}

ssize_t core_alua_store_implicit_trans_secs(
        struct t10_alua_tg_pt_gp *tg_pt_gp,
        const char *page,
        size_t count)
{
        unsigned long tmp;
        int ret;

        ret = kstrtoul(page, 0, &tmp);
        if (ret < 0) {
                pr_err("Unable to extract implicit_trans_secs\n");
                return ret;
        }
        if (tmp > ALUA_MAX_IMPLICIT_TRANS_SECS) {
                pr_err("Passed implicit_trans_secs: %lu, exceeds"
                        " ALUA_MAX_IMPLICIT_TRANS_SECS: %d\n", tmp,
                        ALUA_MAX_IMPLICIT_TRANS_SECS);
                return  -EINVAL;
        }
        tg_pt_gp->tg_pt_gp_implicit_trans_secs = (int)tmp;

        return count;
}

ssize_t core_alua_show_preferred_bit(
        struct t10_alua_tg_pt_gp *tg_pt_gp,
        char *page)
{
        return sprintf(page, "%d\n", tg_pt_gp->tg_pt_gp_pref);
}

ssize_t core_alua_store_preferred_bit(
        struct t10_alua_tg_pt_gp *tg_pt_gp,
        const char *page,
        size_t count)
{
        unsigned long tmp;
        int ret;

        ret = kstrtoul(page, 0, &tmp);
        if (ret < 0) {
                pr_err("Unable to extract preferred ALUA value\n");
                return ret;
        }
        if ((tmp != 0) && (tmp != 1)) {
                pr_err("Illegal value for preferred ALUA: %lu\n", tmp);
                return -EINVAL;
        }
        tg_pt_gp->tg_pt_gp_pref = (int)tmp;

        return count;
}

ssize_t core_alua_show_offline_bit(struct se_lun *lun, char *page)
{
        return sprintf(page, "%d\n",
                atomic_read(&lun->lun_tg_pt_secondary_offline));
}

ssize_t core_alua_store_offline_bit(
        struct se_lun *lun,
        const char *page,
        size_t count)
{
        /*
         * rcu_dereference_raw protected by se_lun->lun_group symlink
         * reference to se_device->dev_group.
         */
        struct se_device *dev = rcu_dereference_raw(lun->lun_se_dev);
        unsigned long tmp;
        int ret;

        if (dev->transport->transport_flags & TRANSPORT_FLAG_PASSTHROUGH_ALUA ||
            (dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE))
                return -ENODEV;

        ret = kstrtoul(page, 0, &tmp);
        if (ret < 0) {
                pr_err("Unable to extract alua_tg_pt_offline value\n");
                return ret;
        }
        if ((tmp != 0) && (tmp != 1)) {
                pr_err("Illegal value for alua_tg_pt_offline: %lu\n",
                                tmp);
                return -EINVAL;
        }

        ret = core_alua_set_tg_pt_secondary_state(lun, 0, (int)tmp);
        if (ret < 0)
                return -EINVAL;

        return count;
}

ssize_t core_alua_show_secondary_status(
        struct se_lun *lun,
        char *page)
{
        return sprintf(page, "%d\n", lun->lun_tg_pt_secondary_stat);
}

ssize_t core_alua_store_secondary_status(
        struct se_lun *lun,
        const char *page,
        size_t count)
{
        unsigned long tmp;
        int ret;

        ret = kstrtoul(page, 0, &tmp);
        if (ret < 0) {
                pr_err("Unable to extract alua_tg_pt_status\n");
                return ret;
        }
        if ((tmp != ALUA_STATUS_NONE) &&
            (tmp != ALUA_STATUS_ALTERED_BY_EXPLICIT_STPG) &&
            (tmp != ALUA_STATUS_ALTERED_BY_IMPLICIT_ALUA)) {
                pr_err("Illegal value for alua_tg_pt_status: %lu\n",
                                tmp);
                return -EINVAL;
        }
        lun->lun_tg_pt_secondary_stat = (int)tmp;

        return count;
}

ssize_t core_alua_show_secondary_write_metadata(
        struct se_lun *lun,
        char *page)
{
        return sprintf(page, "%d\n", lun->lun_tg_pt_secondary_write_md);
}

ssize_t core_alua_store_secondary_write_metadata(
        struct se_lun *lun,
        const char *page,
        size_t count)
{
        unsigned long tmp;
        int ret;

        ret = kstrtoul(page, 0, &tmp);
        if (ret < 0) {
                pr_err("Unable to extract alua_tg_pt_write_md\n");
                return ret;
        }
        if ((tmp != 0) && (tmp != 1)) {
                pr_err("Illegal value for alua_tg_pt_write_md:"
                                " %lu\n", tmp);
                return -EINVAL;
        }
        lun->lun_tg_pt_secondary_write_md = (int)tmp;

        return count;
}

int core_setup_alua(struct se_device *dev)
{
        if (!(dev->transport->transport_flags &
             TRANSPORT_FLAG_PASSTHROUGH_ALUA) &&
            !(dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE)) {
                struct t10_alua_lu_gp_member *lu_gp_mem;

                /*
                 * Associate this struct se_device with the default ALUA
                 * LUN Group.
                 */
                lu_gp_mem = core_alua_allocate_lu_gp_mem(dev);
                if (IS_ERR(lu_gp_mem))
                        return PTR_ERR(lu_gp_mem);

                spin_lock(&lu_gp_mem->lu_gp_mem_lock);
                __core_alua_attach_lu_gp_mem(lu_gp_mem,
                                default_lu_gp);
                spin_unlock(&lu_gp_mem->lu_gp_mem_lock);

                pr_debug("%s: Adding to default ALUA LU Group:"
                        " core/alua/lu_gps/default_lu_gp\n",
                        dev->transport->name);
        }

        return 0;
}