target_core_spc.c

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/*
 * SCSI Primary Commands (SPC) parsing and emulation.
 *
 * Copyright (c) 2002, 2003, 2004, 2005 PyX Technologies, Inc.
 * Copyright (c) 2005, 2006, 2007 SBE, Inc.
 * Copyright (c) 2007-2010 Rising Tide Systems
 * Copyright (c) 2008-2010 Linux-iSCSI.org
 *
 * Nicholas A. Bellinger <[email protected]>
 *
 * 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/kernel.h>
#include <linux/module.h>
#include <asm/unaligned.h>

#include <scsi/scsi.h>
#include <scsi/scsi_tcq.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_pr.h"
#include "target_core_ua.h"


static void spc_fill_alua_data(struct se_port *port, unsigned char *buf)
{
    struct t10_alua_tg_pt_gp *tg_pt_gp;
    struct t10_alua_tg_pt_gp_member *tg_pt_gp_mem;

    /*
     * Set SCCS for MAINTENANCE_IN + REPORT_TARGET_PORT_GROUPS.
     */
    buf[5]  = 0x80;

    /*
     * Set TPGS field for explict and/or implict ALUA access type
     * and opteration.
     *
     * See spc4r17 section 6.4.2 Table 135
     */
    if (!port)
        return;
    tg_pt_gp_mem = port->sep_alua_tg_pt_gp_mem;
    if (!tg_pt_gp_mem)
        return;

    spin_lock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
    tg_pt_gp = tg_pt_gp_mem->tg_pt_gp;
    if (tg_pt_gp)
        buf[5] |= tg_pt_gp->tg_pt_gp_alua_access_type;
    spin_unlock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
}

static int spc_emulate_inquiry_std(struct se_cmd *cmd, char *buf)
{
    struct se_lun *lun = cmd->se_lun;
    struct se_device *dev = cmd->se_dev;

    /* Set RMB (removable media) for tape devices */
    if (dev->transport->get_device_type(dev) == TYPE_TAPE)
        buf[1] = 0x80;

    buf[2] = dev->transport->get_device_rev(dev);

    /*
     * NORMACA and HISUP = 0, RESPONSE DATA FORMAT = 2
     *
     * SPC4 says:
     *   A RESPONSE DATA FORMAT field set to 2h indicates that the
     *   standard INQUIRY data is in the format defined in this
     *   standard. Response data format values less than 2h are
     *   obsolete. Response data format values greater than 2h are
     *   reserved.
     */
    buf[3] = 2;

    /*
     * Enable SCCS and TPGS fields for Emulated ALUA
     */
    if (dev->se_sub_dev->t10_alua.alua_type == SPC3_ALUA_EMULATED)
        spc_fill_alua_data(lun->lun_sep, buf);

    buf[7] = 0x2; /* CmdQue=1 */

    snprintf(&buf[8], 8, "LIO-ORG");
    snprintf(&buf[16], 16, "%s", dev->se_sub_dev->t10_wwn.model);
    snprintf(&buf[32], 4, "%s", dev->se_sub_dev->t10_wwn.revision);
    buf[4] = 31; /* Set additional length to 31 */

    return 0;
}

/* unit serial number */
static int spc_emulate_evpd_80(struct se_cmd *cmd, unsigned char *buf)
{
    struct se_device *dev = cmd->se_dev;
    u16 len = 0;

    if (dev->se_sub_dev->su_dev_flags &
            SDF_EMULATED_VPD_UNIT_SERIAL) {
        u32 unit_serial_len;

        unit_serial_len = strlen(dev->se_sub_dev->t10_wwn.unit_serial);
        unit_serial_len++; /* For NULL Terminator */

        len += sprintf(&buf[4], "%s",
            dev->se_sub_dev->t10_wwn.unit_serial);
        len++; /* Extra Byte for NULL Terminator */
        buf[3] = len;
    }
    return 0;
}

static void spc_parse_naa_6h_vendor_specific(struct se_device *dev,
        unsigned char *buf)
{
    unsigned char *p = &dev->se_sub_dev->t10_wwn.unit_serial[0];
    int cnt;
    bool next = true;

    /*
     * Generate up to 36 bits of VENDOR SPECIFIC IDENTIFIER starting on
     * byte 3 bit 3-0 for NAA IEEE Registered Extended DESIGNATOR field
     * format, followed by 64 bits of VENDOR SPECIFIC IDENTIFIER EXTENSION
     * to complete the payload.  These are based from VPD=0x80 PRODUCT SERIAL
     * NUMBER set via vpd_unit_serial in target_core_configfs.c to ensure
     * per device uniqeness.
     */
    for (cnt = 0; *p && cnt < 13; p++) {
        int val = hex_to_bin(*p);

        if (val < 0)
            continue;

        if (next) {
            next = false;
            buf[cnt++] |= val;
        } else {
            next = true;
            buf[cnt] = val << 4;
        }
    }
}

/*
 * Device identification VPD, for a complete list of
 * DESIGNATOR TYPEs see spc4r17 Table 459.
 */
static int spc_emulate_evpd_83(struct se_cmd *cmd, unsigned char *buf)
{
    struct se_device *dev = cmd->se_dev;
    struct se_lun *lun = cmd->se_lun;
    struct se_port *port = NULL;
    struct se_portal_group *tpg = NULL;
    struct t10_alua_lu_gp_member *lu_gp_mem;
    struct t10_alua_tg_pt_gp *tg_pt_gp;
    struct t10_alua_tg_pt_gp_member *tg_pt_gp_mem;
    unsigned char *prod = &dev->se_sub_dev->t10_wwn.model[0];
    u32 prod_len;
    u32 unit_serial_len, off = 0;
    u16 len = 0, id_len;

    off = 4;

    /*
     * NAA IEEE Registered Extended Assigned designator format, see
     * spc4r17 section 7.7.3.6.5
     *
     * We depend upon a target_core_mod/ConfigFS provided
     * /sys/kernel/config/target/core/$HBA/$DEV/wwn/vpd_unit_serial
     * value in order to return the NAA id.
     */
    if (!(dev->se_sub_dev->su_dev_flags & SDF_EMULATED_VPD_UNIT_SERIAL))
        goto check_t10_vend_desc;

    /* CODE SET == Binary */
    buf[off++] = 0x1;

    /* Set ASSOCIATION == addressed logical unit: 0)b */
    buf[off] = 0x00;

    /* Identifier/Designator type == NAA identifier */
    buf[off++] |= 0x3;
    off++;

    /* Identifier/Designator length */
    buf[off++] = 0x10;

    /*
     * Start NAA IEEE Registered Extended Identifier/Designator
     */
    buf[off++] = (0x6 << 4);

    /*
     * Use OpenFabrics IEEE Company ID: 00 14 05
     */
    buf[off++] = 0x01;
    buf[off++] = 0x40;
    buf[off] = (0x5 << 4);

    /*
     * Return ConfigFS Unit Serial Number information for
     * VENDOR_SPECIFIC_IDENTIFIER and
     * VENDOR_SPECIFIC_IDENTIFIER_EXTENTION
     */
    spc_parse_naa_6h_vendor_specific(dev, &buf[off]);

    len = 20;
    off = (len + 4);

check_t10_vend_desc:
    /*
     * T10 Vendor Identifier Page, see spc4r17 section 7.7.3.4
     */
    id_len = 8; /* For Vendor field */
    prod_len = 4; /* For VPD Header */
    prod_len += 8; /* For Vendor field */
    prod_len += strlen(prod);
    prod_len++; /* For : */

    if (dev->se_sub_dev->su_dev_flags &
            SDF_EMULATED_VPD_UNIT_SERIAL) {
        unit_serial_len =
            strlen(&dev->se_sub_dev->t10_wwn.unit_serial[0]);
        unit_serial_len++; /* For NULL Terminator */

        id_len += sprintf(&buf[off+12], "%s:%s", prod,
                &dev->se_sub_dev->t10_wwn.unit_serial[0]);
    }
    buf[off] = 0x2; /* ASCII */
    buf[off+1] = 0x1; /* T10 Vendor ID */
    buf[off+2] = 0x0;
    memcpy(&buf[off+4], "LIO-ORG", 8);
    /* Extra Byte for NULL Terminator */
    id_len++;
    /* Identifier Length */
    buf[off+3] = id_len;
    /* Header size for Designation descriptor */
    len += (id_len + 4);
    off += (id_len + 4);
    /*
     * struct se_port is only set for INQUIRY VPD=1 through $FABRIC_MOD
     */
    port = lun->lun_sep;
    if (port) {
        struct t10_alua_lu_gp *lu_gp;
        u32 padding, scsi_name_len;
        u16 lu_gp_id = 0;
        u16 tg_pt_gp_id = 0;
        u16 tpgt;

        tpg = port->sep_tpg;
        /*
         * Relative target port identifer, see spc4r17
         * section 7.7.3.7
         *
         * Get the PROTOCOL IDENTIFIER as defined by spc4r17
         * section 7.5.1 Table 362
         */
        buf[off] =
            (tpg->se_tpg_tfo->get_fabric_proto_ident(tpg) << 4);
        buf[off++] |= 0x1; /* CODE SET == Binary */
        buf[off] = 0x80; /* Set PIV=1 */
        /* Set ASSOCIATION == target port: 01b */
        buf[off] |= 0x10;
        /* DESIGNATOR TYPE == Relative target port identifer */
        buf[off++] |= 0x4;
        off++; /* Skip over Reserved */
        buf[off++] = 4; /* DESIGNATOR LENGTH */
        /* Skip over Obsolete field in RTPI payload
         * in Table 472 */
        off += 2;
        buf[off++] = ((port->sep_rtpi >> 8) & 0xff);
        buf[off++] = (port->sep_rtpi & 0xff);
        len += 8; /* Header size + Designation descriptor */
        /*
         * Target port group identifier, see spc4r17
         * section 7.7.3.8
         *
         * Get the PROTOCOL IDENTIFIER as defined by spc4r17
         * section 7.5.1 Table 362
         */
        if (dev->se_sub_dev->t10_alua.alua_type !=
                SPC3_ALUA_EMULATED)
            goto check_scsi_name;

        tg_pt_gp_mem = port->sep_alua_tg_pt_gp_mem;
        if (!tg_pt_gp_mem)
            goto check_lu_gp;

        spin_lock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
        tg_pt_gp = tg_pt_gp_mem->tg_pt_gp;
        if (!tg_pt_gp) {
            spin_unlock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);
            goto check_lu_gp;
        }
        tg_pt_gp_id = tg_pt_gp->tg_pt_gp_id;
        spin_unlock(&tg_pt_gp_mem->tg_pt_gp_mem_lock);

        buf[off] =
            (tpg->se_tpg_tfo->get_fabric_proto_ident(tpg) << 4);
        buf[off++] |= 0x1; /* CODE SET == Binary */
        buf[off] = 0x80; /* Set PIV=1 */
        /* Set ASSOCIATION == target port: 01b */
        buf[off] |= 0x10;
        /* DESIGNATOR TYPE == Target port group identifier */
        buf[off++] |= 0x5;
        off++; /* Skip over Reserved */
        buf[off++] = 4; /* DESIGNATOR LENGTH */
        off += 2; /* Skip over Reserved Field */
        buf[off++] = ((tg_pt_gp_id >> 8) & 0xff);
        buf[off++] = (tg_pt_gp_id & 0xff);
        len += 8; /* Header size + Designation descriptor */
        /*
         * Logical Unit Group identifier, see spc4r17
         * section 7.7.3.8
         */
check_lu_gp:
        lu_gp_mem = dev->dev_alua_lu_gp_mem;
        if (!lu_gp_mem)
            goto check_scsi_name;

        spin_lock(&lu_gp_mem->lu_gp_mem_lock);
        lu_gp = lu_gp_mem->lu_gp;
        if (!lu_gp) {
            spin_unlock(&lu_gp_mem->lu_gp_mem_lock);
            goto check_scsi_name;
        }
        lu_gp_id = lu_gp->lu_gp_id;
        spin_unlock(&lu_gp_mem->lu_gp_mem_lock);

        buf[off++] |= 0x1; /* CODE SET == Binary */
        /* DESIGNATOR TYPE == Logical Unit Group identifier */
        buf[off++] |= 0x6;
        off++; /* Skip over Reserved */
        buf[off++] = 4; /* DESIGNATOR LENGTH */
        off += 2; /* Skip over Reserved Field */
        buf[off++] = ((lu_gp_id >> 8) & 0xff);
        buf[off++] = (lu_gp_id & 0xff);
        len += 8; /* Header size + Designation descriptor */
        /*
         * SCSI name string designator, see spc4r17
         * section 7.7.3.11
         *
         * Get the PROTOCOL IDENTIFIER as defined by spc4r17
         * section 7.5.1 Table 362
         */
check_scsi_name:
        scsi_name_len = strlen(tpg->se_tpg_tfo->tpg_get_wwn(tpg));
        /* UTF-8 ",t,0x<16-bit TPGT>" + NULL Terminator */
        scsi_name_len += 10;
        /* Check for 4-byte padding */
        padding = ((-scsi_name_len) & 3);
        if (padding != 0)
            scsi_name_len += padding;
        /* Header size + Designation descriptor */
        scsi_name_len += 4;

        buf[off] =
            (tpg->se_tpg_tfo->get_fabric_proto_ident(tpg) << 4);
        buf[off++] |= 0x3; /* CODE SET == UTF-8 */
        buf[off] = 0x80; /* Set PIV=1 */
        /* Set ASSOCIATION == target port: 01b */
        buf[off] |= 0x10;
        /* DESIGNATOR TYPE == SCSI name string */
        buf[off++] |= 0x8;
        off += 2; /* Skip over Reserved and length */
        /*
         * SCSI name string identifer containing, $FABRIC_MOD
         * dependent information.  For LIO-Target and iSCSI
         * Target Port, this means "<iSCSI name>,t,0x<TPGT> in
         * UTF-8 encoding.
         */
        tpgt = tpg->se_tpg_tfo->tpg_get_tag(tpg);
        scsi_name_len = sprintf(&buf[off], "%s,t,0x%04x",
                    tpg->se_tpg_tfo->tpg_get_wwn(tpg), tpgt);
        scsi_name_len += 1 /* Include  NULL terminator */;
        /*
         * The null-terminated, null-padded (see 4.4.2) SCSI
         * NAME STRING field contains a UTF-8 format string.
         * The number of bytes in the SCSI NAME STRING field
         * (i.e., the value in the DESIGNATOR LENGTH field)
         * shall be no larger than 256 and shall be a multiple
         * of four.
         */
        if (padding)
            scsi_name_len += padding;

        buf[off-1] = scsi_name_len;
        off += scsi_name_len;
        /* Header size + Designation descriptor */
        len += (scsi_name_len + 4);
    }
    buf[2] = ((len >> 8) & 0xff);
    buf[3] = (len & 0xff); /* Page Length for VPD 0x83 */
    return 0;
}

/* Extended INQUIRY Data VPD Page */
static int spc_emulate_evpd_86(struct se_cmd *cmd, unsigned char *buf)
{
    buf[3] = 0x3c;
    /* Set HEADSUP, ORDSUP, SIMPSUP */
    buf[5] = 0x07;

    /* If WriteCache emulation is enabled, set V_SUP */
    if (cmd->se_dev->se_sub_dev->se_dev_attrib.emulate_write_cache > 0)
        buf[6] = 0x01;
    return 0;
}

/* Block Limits VPD page */
static int spc_emulate_evpd_b0(struct se_cmd *cmd, unsigned char *buf)
{
    struct se_device *dev = cmd->se_dev;
    u32 max_sectors;
    int have_tp = 0;

    /*
     * Following spc3r22 section 6.5.3 Block Limits VPD page, when
     * emulate_tpu=1 or emulate_tpws=1 we will be expect a
     * different page length for Thin Provisioning.
     */
    if (dev->se_sub_dev->se_dev_attrib.emulate_tpu || dev->se_sub_dev->se_dev_attrib.emulate_tpws)
        have_tp = 1;

    buf[0] = dev->transport->get_device_type(dev);
    buf[3] = have_tp ? 0x3c : 0x10;

    /* Set WSNZ to 1 */
    buf[4] = 0x01;

    /*
     * Set OPTIMAL TRANSFER LENGTH GRANULARITY
     */
    put_unaligned_be16(1, &buf[6]);

    /*
     * Set MAXIMUM TRANSFER LENGTH
     */
    max_sectors = min(dev->se_sub_dev->se_dev_attrib.fabric_max_sectors,
              dev->se_sub_dev->se_dev_attrib.hw_max_sectors);
    put_unaligned_be32(max_sectors, &buf[8]);

    /*
     * Set OPTIMAL TRANSFER LENGTH
     */
    put_unaligned_be32(dev->se_sub_dev->se_dev_attrib.optimal_sectors, &buf[12]);

    /*
     * Exit now if we don't support TP.
     */
    if (!have_tp)
        return 0;

    /*
     * Set MAXIMUM UNMAP LBA COUNT
     */
    put_unaligned_be32(dev->se_sub_dev->se_dev_attrib.max_unmap_lba_count, &buf[20]);

    /*
     * Set MAXIMUM UNMAP BLOCK DESCRIPTOR COUNT
     */
    put_unaligned_be32(dev->se_sub_dev->se_dev_attrib.max_unmap_block_desc_count,
               &buf[24]);

    /*
     * Set OPTIMAL UNMAP GRANULARITY
     */
    put_unaligned_be32(dev->se_sub_dev->se_dev_attrib.unmap_granularity, &buf[28]);

    /*
     * UNMAP GRANULARITY ALIGNMENT
     */
    put_unaligned_be32(dev->se_sub_dev->se_dev_attrib.unmap_granularity_alignment,
               &buf[32]);
    if (dev->se_sub_dev->se_dev_attrib.unmap_granularity_alignment != 0)
        buf[32] |= 0x80; /* Set the UGAVALID bit */

    return 0;
}

/* Block Device Characteristics VPD page */
static int spc_emulate_evpd_b1(struct se_cmd *cmd, unsigned char *buf)
{
    struct se_device *dev = cmd->se_dev;

    buf[0] = dev->transport->get_device_type(dev);
    buf[3] = 0x3c;
    buf[5] = dev->se_sub_dev->se_dev_attrib.is_nonrot ? 1 : 0;

    return 0;
}

/* Thin Provisioning VPD */
static int spc_emulate_evpd_b2(struct se_cmd *cmd, unsigned char *buf)
{
    struct se_device *dev = cmd->se_dev;

    /*
     * From spc3r22 section 6.5.4 Thin Provisioning VPD page:
     *
     * The PAGE LENGTH field is defined in SPC-4. If the DP bit is set to
     * zero, then the page length shall be set to 0004h.  If the DP bit
     * is set to one, then the page length shall be set to the value
     * defined in table 162.
     */
    buf[0] = dev->transport->get_device_type(dev);

    /*
     * Set Hardcoded length mentioned above for DP=0
     */
    put_unaligned_be16(0x0004, &buf[2]);

    /*
     * The THRESHOLD EXPONENT field indicates the threshold set size in
     * LBAs as a power of 2 (i.e., the threshold set size is equal to
     * 2(threshold exponent)).
     *
     * Note that this is currently set to 0x00 as mkp says it will be
     * changing again.  We can enable this once it has settled in T10
     * and is actually used by Linux/SCSI ML code.
     */
    buf[4] = 0x00;

    /*
     * A TPU bit set to one indicates that the device server supports
     * the UNMAP command (see 5.25). A TPU bit set to zero indicates
     * that the device server does not support the UNMAP command.
     */
    if (dev->se_sub_dev->se_dev_attrib.emulate_tpu != 0)
        buf[5] = 0x80;

    /*
     * A TPWS bit set to one indicates that the device server supports
     * the use of the WRITE SAME (16) command (see 5.42) to unmap LBAs.
     * A TPWS bit set to zero indicates that the device server does not
     * support the use of the WRITE SAME (16) command to unmap LBAs.
     */
    if (dev->se_sub_dev->se_dev_attrib.emulate_tpws != 0)
        buf[5] |= 0x40;

    return 0;
}

static int spc_emulate_evpd_00(struct se_cmd *cmd, unsigned char *buf);

static struct {
    uint8_t     page;
    int     (*emulate)(struct se_cmd *, unsigned char *);
} evpd_handlers[] = {
    { .page = 0x00, .emulate = spc_emulate_evpd_00 },
    { .page = 0x80, .emulate = spc_emulate_evpd_80 },
    { .page = 0x83, .emulate = spc_emulate_evpd_83 },
    { .page = 0x86, .emulate = spc_emulate_evpd_86 },
    { .page = 0xb0, .emulate = spc_emulate_evpd_b0 },
    { .page = 0xb1, .emulate = spc_emulate_evpd_b1 },
    { .page = 0xb2, .emulate = spc_emulate_evpd_b2 },
};

/* supported vital product data pages */
static int spc_emulate_evpd_00(struct se_cmd *cmd, unsigned char *buf)
{
    int p;

    /*
     * Only report the INQUIRY EVPD=1 pages after a valid NAA
     * Registered Extended LUN WWN has been set via ConfigFS
     * during device creation/restart.
     */
    if (cmd->se_dev->se_sub_dev->su_dev_flags &
            SDF_EMULATED_VPD_UNIT_SERIAL) {
        buf[3] = ARRAY_SIZE(evpd_handlers);
        for (p = 0; p < ARRAY_SIZE(evpd_handlers); ++p)
            buf[p + 4] = evpd_handlers[p].page;
    }

    return 0;
}

static int spc_emulate_inquiry(struct se_cmd *cmd)
{
    struct se_device *dev = cmd->se_dev;
    struct se_portal_group *tpg = cmd->se_lun->lun_sep->sep_tpg;
    unsigned char *rbuf;
    unsigned char *cdb = cmd->t_task_cdb;
    unsigned char buf[SE_INQUIRY_BUF];
    int p, ret;

    memset(buf, 0, SE_INQUIRY_BUF);

    if (dev == tpg->tpg_virt_lun0.lun_se_dev)
        buf[0] = 0x3f; /* Not connected */
    else
        buf[0] = dev->transport->get_device_type(dev);

    if (!(cdb[1] & 0x1)) {
        if (cdb[2]) {
            pr_err("INQUIRY with EVPD==0 but PAGE CODE=%02x\n",
                   cdb[2]);
            cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;
            ret = -EINVAL;
            goto out;
        }

        ret = spc_emulate_inquiry_std(cmd, buf);
        goto out;
    }

    for (p = 0; p < ARRAY_SIZE(evpd_handlers); ++p) {
        if (cdb[2] == evpd_handlers[p].page) {
            buf[1] = cdb[2];
            ret = evpd_handlers[p].emulate(cmd, buf);
            goto out;
        }
    }

    pr_err("Unknown VPD Code: 0x%02x\n", cdb[2]);
    cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;
    ret = -EINVAL;

out:
    rbuf = transport_kmap_data_sg(cmd);
    if (rbuf) {
        memcpy(rbuf, buf, min_t(u32, sizeof(buf), cmd->data_length));
        transport_kunmap_data_sg(cmd);
    }

    if (!ret)
        target_complete_cmd(cmd, GOOD);
    return ret;
}

static int spc_modesense_rwrecovery(unsigned char *p)
{
    p[0] = 0x01;
    p[1] = 0x0a;

    return 12;
}

static int spc_modesense_control(struct se_device *dev, unsigned char *p)
{
    p[0] = 0x0a;
    p[1] = 0x0a;
    p[2] = 2;
    /*
     * From spc4r23, 7.4.7 Control mode page
     *
     * The QUEUE ALGORITHM MODIFIER field (see table 368) specifies
     * restrictions on the algorithm used for reordering commands
     * having the SIMPLE task attribute (see SAM-4).
     *
     *                    Table 368 -- QUEUE ALGORITHM MODIFIER field
     *                         Code      Description
     *                          0h       Restricted reordering
     *                          1h       Unrestricted reordering allowed
     *                          2h to 7h    Reserved
     *                          8h to Fh    Vendor specific
     *
     * A value of zero in the QUEUE ALGORITHM MODIFIER field specifies that
     * the device server shall order the processing sequence of commands
     * having the SIMPLE task attribute such that data integrity is maintained
     * for that I_T nexus (i.e., if the transmission of new SCSI transport protocol
     * requests is halted at any time, the final value of all data observable
     * on the medium shall be the same as if all the commands had been processed
     * with the ORDERED task attribute).
     *
     * A value of one in the QUEUE ALGORITHM MODIFIER field specifies that the
     * device server may reorder the processing sequence of commands having the
     * SIMPLE task attribute in any manner. Any data integrity exposures related to
     * command sequence order shall be explicitly handled by the application client
     * through the selection of appropriate ommands and task attributes.
     */
    p[3] = (dev->se_sub_dev->se_dev_attrib.emulate_rest_reord == 1) ? 0x00 : 0x10;
    /*
     * From spc4r17, section 7.4.6 Control mode Page
     *
     * Unit Attention interlocks control (UN_INTLCK_CTRL) to code 00b
     *
     * 00b: The logical unit shall clear any unit attention condition
     * reported in the same I_T_L_Q nexus transaction as a CHECK CONDITION
     * status and shall not establish a unit attention condition when a com-
     * mand is completed with BUSY, TASK SET FULL, or RESERVATION CONFLICT
     * status.
     *
     * 10b: The logical unit shall not clear any unit attention condition
     * reported in the same I_T_L_Q nexus transaction as a CHECK CONDITION
     * status and shall not establish a unit attention condition when
     * a command is completed with BUSY, TASK SET FULL, or RESERVATION
     * CONFLICT status.
     *
     * 11b a The logical unit shall not clear any unit attention condition
     * reported in the same I_T_L_Q nexus transaction as a CHECK CONDITION
     * status and shall establish a unit attention condition for the
     * initiator port associated with the I_T nexus on which the BUSY,
     * TASK SET FULL, or RESERVATION CONFLICT status is being returned.
     * Depending on the status, the additional sense code shall be set to
     * PREVIOUS BUSY STATUS, PREVIOUS TASK SET FULL STATUS, or PREVIOUS
     * RESERVATION CONFLICT STATUS. Until it is cleared by a REQUEST SENSE
     * command, a unit attention condition shall be established only once
     * for a BUSY, TASK SET FULL, or RESERVATION CONFLICT status regardless
     * to the number of commands completed with one of those status codes.
     */
    p[4] = (dev->se_sub_dev->se_dev_attrib.emulate_ua_intlck_ctrl == 2) ? 0x30 :
           (dev->se_sub_dev->se_dev_attrib.emulate_ua_intlck_ctrl == 1) ? 0x20 : 0x00;
    /*
     * From spc4r17, section 7.4.6 Control mode Page
     *
     * Task Aborted Status (TAS) bit set to zero.
     *
     * A task aborted status (TAS) bit set to zero specifies that aborted
     * tasks shall be terminated by the device server without any response
     * to the application client. A TAS bit set to one specifies that tasks
     * aborted by the actions of an I_T nexus other than the I_T nexus on
     * which the command was received shall be completed with TASK ABORTED
     * status (see SAM-4).
     */
    p[5] = (dev->se_sub_dev->se_dev_attrib.emulate_tas) ? 0x40 : 0x00;
    p[8] = 0xff;
    p[9] = 0xff;
    p[11] = 30;

    return 12;
}

static int spc_modesense_caching(struct se_device *dev, unsigned char *p)
{
    p[0] = 0x08;
    p[1] = 0x12;
    if (dev->se_sub_dev->se_dev_attrib.emulate_write_cache > 0)
        p[2] = 0x04; /* Write Cache Enable */
    p[12] = 0x20; /* Disabled Read Ahead */

    return 20;
}

static void spc_modesense_write_protect(unsigned char *buf, int type)
{
    /*
     * I believe that the WP bit (bit 7) in the mode header is the same for
     * all device types..
     */
    switch (type) {
    case TYPE_DISK:
    case TYPE_TAPE:
    default:
        buf[0] |= 0x80; /* WP bit */
        break;
    }
}

static void spc_modesense_dpofua(unsigned char *buf, int type)
{
    switch (type) {
    case TYPE_DISK:
        buf[0] |= 0x10; /* DPOFUA bit */
        break;
    default:
        break;
    }
}

static int spc_emulate_modesense(struct se_cmd *cmd)
{
    struct se_device *dev = cmd->se_dev;
    char *cdb = cmd->t_task_cdb;
    unsigned char *rbuf;
    int type = dev->transport->get_device_type(dev);
    int ten = (cmd->t_task_cdb[0] == MODE_SENSE_10);
    u32 offset = ten ? 8 : 4;
    int length = 0;
    unsigned char buf[SE_MODE_PAGE_BUF];

    memset(buf, 0, SE_MODE_PAGE_BUF);

    switch (cdb[2] & 0x3f) {
    case 0x01:
        length = spc_modesense_rwrecovery(&buf[offset]);
        break;
    case 0x08:
        length = spc_modesense_caching(dev, &buf[offset]);
        break;
    case 0x0a:
        length = spc_modesense_control(dev, &buf[offset]);
        break;
    case 0x3f:
        length = spc_modesense_rwrecovery(&buf[offset]);
        length += spc_modesense_caching(dev, &buf[offset+length]);
        length += spc_modesense_control(dev, &buf[offset+length]);
        break;
    default:
        pr_err("MODE SENSE: unimplemented page/subpage: 0x%02x/0x%02x\n",
               cdb[2] & 0x3f, cdb[3]);
        cmd->scsi_sense_reason = TCM_UNKNOWN_MODE_PAGE;
        return -EINVAL;
    }
    offset += length;

    if (ten) {
        offset -= 2;
        buf[0] = (offset >> 8) & 0xff;
        buf[1] = offset & 0xff;
        offset += 2;

        if ((cmd->se_lun->lun_access & TRANSPORT_LUNFLAGS_READ_ONLY) ||
            (cmd->se_deve &&
            (cmd->se_deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY)))
            spc_modesense_write_protect(&buf[3], type);

        if ((dev->se_sub_dev->se_dev_attrib.emulate_write_cache > 0) &&
            (dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0))
            spc_modesense_dpofua(&buf[3], type);
    } else {
        offset -= 1;
        buf[0] = offset & 0xff;
        offset += 1;

        if ((cmd->se_lun->lun_access & TRANSPORT_LUNFLAGS_READ_ONLY) ||
            (cmd->se_deve &&
            (cmd->se_deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY)))
            spc_modesense_write_protect(&buf[2], type);

        if ((dev->se_sub_dev->se_dev_attrib.emulate_write_cache > 0) &&
            (dev->se_sub_dev->se_dev_attrib.emulate_fua_write > 0))
            spc_modesense_dpofua(&buf[2], type);
    }

    rbuf = transport_kmap_data_sg(cmd);
    if (rbuf) {
        memcpy(rbuf, buf, min(offset, cmd->data_length));
        transport_kunmap_data_sg(cmd);
    }

    target_complete_cmd(cmd, GOOD);
    return 0;
}

static int spc_emulate_request_sense(struct se_cmd *cmd)
{
    unsigned char *cdb = cmd->t_task_cdb;
    unsigned char *rbuf;
    u8 ua_asc = 0, ua_ascq = 0;
    unsigned char buf[SE_SENSE_BUF];

    memset(buf, 0, SE_SENSE_BUF);

    if (cdb[1] & 0x01) {
        pr_err("REQUEST_SENSE description emulation not"
            " supported\n");
        cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;
        return -ENOSYS;
    }

    rbuf = transport_kmap_data_sg(cmd);
    if (cmd->scsi_sense_reason != 0) {
        /*
         * Out of memory.  We will fail with CHECK CONDITION, so
         * we must not clear the unit attention condition.
         */
        target_complete_cmd(cmd, CHECK_CONDITION);
        return 0;
    } else if (!core_scsi3_ua_clear_for_request_sense(cmd, &ua_asc, &ua_ascq)) {
        /*
         * CURRENT ERROR, UNIT ATTENTION
         */
        buf[0] = 0x70;
        buf[SPC_SENSE_KEY_OFFSET] = UNIT_ATTENTION;

        /*
         * The Additional Sense Code (ASC) from the UNIT ATTENTION
         */
        buf[SPC_ASC_KEY_OFFSET] = ua_asc;
        buf[SPC_ASCQ_KEY_OFFSET] = ua_ascq;
        buf[7] = 0x0A;
    } else {
        /*
         * CURRENT ERROR, NO SENSE
         */
        buf[0] = 0x70;
        buf[SPC_SENSE_KEY_OFFSET] = NO_SENSE;

        /*
         * NO ADDITIONAL SENSE INFORMATION
         */
        buf[SPC_ASC_KEY_OFFSET] = 0x00;
        buf[7] = 0x0A;
    }

    if (rbuf) {
        memcpy(rbuf, buf, min_t(u32, sizeof(buf), cmd->data_length));
        transport_kunmap_data_sg(cmd);
    }

    target_complete_cmd(cmd, GOOD);
    return 0;
}

static int spc_emulate_testunitready(struct se_cmd *cmd)
{
    target_complete_cmd(cmd, GOOD);
    return 0;
}

int spc_parse_cdb(struct se_cmd *cmd, unsigned int *size)
{
    struct se_device *dev = cmd->se_dev;
    struct se_subsystem_dev *su_dev = dev->se_sub_dev;
    unsigned char *cdb = cmd->t_task_cdb;

    switch (cdb[0]) {
    case MODE_SELECT:
        *size = cdb[4];
        break;
    case MODE_SELECT_10:
        *size = (cdb[7] << 8) + cdb[8];
        break;
    case MODE_SENSE:
        *size = cdb[4];
        cmd->execute_cmd = spc_emulate_modesense;
        break;
    case MODE_SENSE_10:
        *size = (cdb[7] << 8) + cdb[8];
        cmd->execute_cmd = spc_emulate_modesense;
        break;
    case LOG_SELECT:
    case LOG_SENSE:
        *size = (cdb[7] << 8) + cdb[8];
        break;
    case PERSISTENT_RESERVE_IN:
        if (su_dev->t10_pr.res_type == SPC3_PERSISTENT_RESERVATIONS)
            cmd->execute_cmd = target_scsi3_emulate_pr_in;
        *size = (cdb[7] << 8) + cdb[8];
        break;
    case PERSISTENT_RESERVE_OUT:
        if (su_dev->t10_pr.res_type == SPC3_PERSISTENT_RESERVATIONS)
            cmd->execute_cmd = target_scsi3_emulate_pr_out;
        *size = (cdb[7] << 8) + cdb[8];
        break;
    case RELEASE:
    case RELEASE_10:
        if (cdb[0] == RELEASE_10)
            *size = (cdb[7] << 8) | cdb[8];
        else
            *size = cmd->data_length;

        if (su_dev->t10_pr.res_type != SPC_PASSTHROUGH)
            cmd->execute_cmd = target_scsi2_reservation_release;
        break;
    case RESERVE:
    case RESERVE_10:
        /*
         * The SPC-2 RESERVE does not contain a size in the SCSI CDB.
         * Assume the passthrough or $FABRIC_MOD will tell us about it.
         */
        if (cdb[0] == RESERVE_10)
            *size = (cdb[7] << 8) | cdb[8];
        else
            *size = cmd->data_length;

        /*
         * Setup the legacy emulated handler for SPC-2 and
         * >= SPC-3 compatible reservation handling (CRH=1)
         * Otherwise, we assume the underlying SCSI logic is
         * is running in SPC_PASSTHROUGH, and wants reservations
         * emulation disabled.
         */
        if (su_dev->t10_pr.res_type != SPC_PASSTHROUGH)
            cmd->execute_cmd = target_scsi2_reservation_reserve;
        break;
    case REQUEST_SENSE:
        *size = cdb[4];
        cmd->execute_cmd = spc_emulate_request_sense;
        break;
    case INQUIRY:
        *size = (cdb[3] << 8) + cdb[4];

        /*
         * Do implict HEAD_OF_QUEUE processing for INQUIRY.
         * See spc4r17 section 5.3
         */
        if (cmd->se_dev->dev_task_attr_type == SAM_TASK_ATTR_EMULATED)
            cmd->sam_task_attr = MSG_HEAD_TAG;
        cmd->execute_cmd = spc_emulate_inquiry;
        break;
    case SECURITY_PROTOCOL_IN:
    case SECURITY_PROTOCOL_OUT:
        *size = (cdb[6] << 24) | (cdb[7] << 16) | (cdb[8] << 8) | cdb[9];
        break;
    case EXTENDED_COPY:
    case READ_ATTRIBUTE:
    case RECEIVE_COPY_RESULTS:
    case WRITE_ATTRIBUTE:
        *size = (cdb[10] << 24) | (cdb[11] << 16) |
               (cdb[12] << 8) | cdb[13];
        break;
    case RECEIVE_DIAGNOSTIC:
    case SEND_DIAGNOSTIC:
        *size = (cdb[3] << 8) | cdb[4];
        break;
    case WRITE_BUFFER:
        *size = (cdb[6] << 16) + (cdb[7] << 8) + cdb[8];
        break;
    case REPORT_LUNS:
        cmd->execute_cmd = target_report_luns;
        *size = (cdb[6] << 24) | (cdb[7] << 16) | (cdb[8] << 8) | cdb[9];
        /*
         * Do implict HEAD_OF_QUEUE processing for REPORT_LUNS
         * See spc4r17 section 5.3
         */
        if (cmd->se_dev->dev_task_attr_type == SAM_TASK_ATTR_EMULATED)
            cmd->sam_task_attr = MSG_HEAD_TAG;
        break;
    case TEST_UNIT_READY:
        cmd->execute_cmd = spc_emulate_testunitready;
        *size = 0;
        break;
    case MAINTENANCE_IN:
        if (dev->transport->get_device_type(dev) != TYPE_ROM) {
            /*
             * MAINTENANCE_IN from SCC-2
             * Check for emulated MI_REPORT_TARGET_PGS
             */
            if ((cdb[1] & 0x1f) == MI_REPORT_TARGET_PGS &&
                su_dev->t10_alua.alua_type == SPC3_ALUA_EMULATED) {
                cmd->execute_cmd =
                    target_emulate_report_target_port_groups;
            }
            *size = get_unaligned_be32(&cdb[6]);
        } else {
            /*
             * GPCMD_SEND_KEY from multi media commands
             */
            *size = get_unaligned_be16(&cdb[8]);
        }
        break;
    case MAINTENANCE_OUT:
        if (dev->transport->get_device_type(dev) != TYPE_ROM) {
            /*
             * MAINTENANCE_OUT from SCC-2
             * Check for emulated MO_SET_TARGET_PGS.
             */
            if (cdb[1] == MO_SET_TARGET_PGS &&
                su_dev->t10_alua.alua_type == SPC3_ALUA_EMULATED) {
                cmd->execute_cmd =
                    target_emulate_set_target_port_groups;
            }
            *size = get_unaligned_be32(&cdb[6]);
        } else {
            /*
             * GPCMD_SEND_KEY from multi media commands
             */
            *size = get_unaligned_be16(&cdb[8]);
        }
        break;
    default:
        pr_warn("TARGET_CORE[%s]: Unsupported SCSI Opcode"
            " 0x%02x, sending CHECK_CONDITION.\n",
            cmd->se_tfo->get_fabric_name(), cdb[0]);
        cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
        cmd->scsi_sense_reason = TCM_UNSUPPORTED_SCSI_OPCODE;
        return -EINVAL;
    }

    return 0;
}
EXPORT_SYMBOL(spc_parse_cdb);