Merge branch 'drm-nouveau-fixes-3.9' of git://anongit.freedesktop.org/git/nouveau...

[linux-2.6/libata-dev.git] / drivers / target / target_core_spc.c

/*
 * SCSI Primary Commands (SPC) parsing and emulation.
 *
 * (c) Copyright 2002-2012 RisingTide Systems LLC.
 *
 * Nicholas A. Bellinger <nab@kernel.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include <linux/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);
}

sense_reason_t
spc_emulate_inquiry_std(struct se_cmd *cmd, unsigned 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] = 0x05; /* SPC-3 */

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

        return 0;
}
EXPORT_SYMBOL(spc_emulate_inquiry_std);

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

        if (dev->dev_flags & DF_EMULATED_VPD_UNIT_SERIAL) {
                u32 unit_serial_len;

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

                len += sprintf(&buf[4], "%s", 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->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.
 */
sense_reason_t
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->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->dev_flags & DF_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->dev_flags & DF_EMULATED_VPD_UNIT_SERIAL) {
                unit_serial_len = strlen(&dev->t10_wwn.unit_serial[0]);
                unit_serial_len++; /* For NULL Terminator */

                id_len += sprintf(&buf[off+12], "%s:%s", prod,
                                &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
                 */
                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;
}
EXPORT_SYMBOL(spc_emulate_evpd_83);

static bool
spc_check_dev_wce(struct se_device *dev)
{
        bool wce = false;

        if (dev->transport->get_write_cache)
                wce = dev->transport->get_write_cache(dev);
        else if (dev->dev_attrib.emulate_write_cache > 0)
                wce = true;

        return wce;
}

/* Extended INQUIRY Data VPD Page */
static sense_reason_t
spc_emulate_evpd_86(struct se_cmd *cmd, unsigned char *buf)
{
        struct se_device *dev = cmd->se_dev;

        buf[3] = 0x3c;
        /* Set HEADSUP, ORDSUP, SIMPSUP */
        buf[5] = 0x07;

        /* If WriteCache emulation is enabled, set V_SUP */
        if (spc_check_dev_wce(dev))
                buf[6] = 0x01;
        return 0;
}

/* Block Limits VPD page */
static sense_reason_t
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->dev_attrib.emulate_tpu || dev->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->dev_attrib.fabric_max_sectors,
                          dev->dev_attrib.hw_max_sectors);
        put_unaligned_be32(max_sectors, &buf[8]);

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

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

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

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

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

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

        /*
         * MAXIMUM WRITE SAME LENGTH
         */
max_write_same:
        put_unaligned_be64(dev->dev_attrib.max_write_same_len, &buf[36]);

        return 0;
}

/* Block Device Characteristics VPD page */
static sense_reason_t
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->dev_attrib.is_nonrot ? 1 : 0;

        return 0;
}

/* Thin Provisioning VPD */
static sense_reason_t
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->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->dev_attrib.emulate_tpws != 0)
                buf[5] |= 0x40;

        return 0;
}

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

static struct {
        uint8_t         page;
        sense_reason_t  (*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 sense_reason_t
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->dev_flags & DF_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 sense_reason_t
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];
        sense_reason_t ret;
        int p;

        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]);
                        ret = TCM_INVALID_CDB_FIELD;
                        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]);
        ret = TCM_INVALID_CDB_FIELD;

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(struct se_device *dev, u8 pc, u8 *p)
{
        p[0] = 0x01;
        p[1] = 0x0a;

        /* No changeable values for now */
        if (pc == 1)
                goto out;

out:
        return 12;
}

static int spc_modesense_control(struct se_device *dev, u8 pc, u8 *p)
{
        p[0] = 0x0a;
        p[1] = 0x0a;

        /* No changeable values for now */
        if (pc == 1)
                goto out;

        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->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->dev_attrib.emulate_ua_intlck_ctrl == 2) ? 0x30 :
               (dev->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->dev_attrib.emulate_tas) ? 0x40 : 0x00;
        p[8] = 0xff;
        p[9] = 0xff;
        p[11] = 30;

out:
        return 12;
}

static int spc_modesense_caching(struct se_device *dev, u8 pc, u8 *p)
{
        p[0] = 0x08;
        p[1] = 0x12;

        /* No changeable values for now */
        if (pc == 1)
                goto out;

        if (spc_check_dev_wce(dev))
                p[2] = 0x04; /* Write Cache Enable */
        p[12] = 0x20; /* Disabled Read Ahead */

out:
        return 20;
}

static int spc_modesense_informational_exceptions(struct se_device *dev, u8 pc, unsigned char *p)
{
        p[0] = 0x1c;
        p[1] = 0x0a;

        /* No changeable values for now */
        if (pc == 1)
                goto out;

out:
        return 12;
}

static struct {
        uint8_t         page;
        uint8_t         subpage;
        int             (*emulate)(struct se_device *, u8, unsigned char *);
} modesense_handlers[] = {
        { .page = 0x01, .subpage = 0x00, .emulate = spc_modesense_rwrecovery },
        { .page = 0x08, .subpage = 0x00, .emulate = spc_modesense_caching },
        { .page = 0x0a, .subpage = 0x00, .emulate = spc_modesense_control },
        { .page = 0x1c, .subpage = 0x00, .emulate = spc_modesense_informational_exceptions },
};

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_modesense_blockdesc(unsigned char *buf, u64 blocks, u32 block_size)
{
        *buf++ = 8;
        put_unaligned_be32(min(blocks, 0xffffffffull), buf);
        buf += 4;
        put_unaligned_be32(block_size, buf);
        return 9;
}

static int spc_modesense_long_blockdesc(unsigned char *buf, u64 blocks, u32 block_size)
{
        if (blocks <= 0xffffffff)
                return spc_modesense_blockdesc(buf + 3, blocks, block_size) + 3;

        *buf++ = 1;             /* LONGLBA */
        buf += 2;
        *buf++ = 16;
        put_unaligned_be64(blocks, buf);
        buf += 12;
        put_unaligned_be32(block_size, buf);

        return 17;
}

static sense_reason_t spc_emulate_modesense(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        char *cdb = cmd->t_task_cdb;
        unsigned char buf[SE_MODE_PAGE_BUF], *rbuf;
        int type = dev->transport->get_device_type(dev);
        int ten = (cmd->t_task_cdb[0] == MODE_SENSE_10);
        bool dbd = !!(cdb[1] & 0x08);
        bool llba = ten ? !!(cdb[1] & 0x10) : false;
        u8 pc = cdb[2] >> 6;
        u8 page = cdb[2] & 0x3f;
        u8 subpage = cdb[3];
        int length = 0;
        int ret;
        int i;

        memset(buf, 0, SE_MODE_PAGE_BUF);

        /*
         * Skip over MODE DATA LENGTH + MEDIUM TYPE fields to byte 3 for
         * MODE_SENSE_10 and byte 2 for MODE_SENSE (6).
         */
        length = ten ? 3 : 2;

        /* DEVICE-SPECIFIC PARAMETER */
        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[length], type);

        if ((spc_check_dev_wce(dev)) &&
            (dev->dev_attrib.emulate_fua_write > 0))
                spc_modesense_dpofua(&buf[length], type);

        ++length;

        /* BLOCK DESCRIPTOR */

        /*
         * For now we only include a block descriptor for disk (SBC)
         * devices; other command sets use a slightly different format.
         */
        if (!dbd && type == TYPE_DISK) {
                u64 blocks = dev->transport->get_blocks(dev);
                u32 block_size = dev->dev_attrib.block_size;

                if (ten) {
                        if (llba) {
                                length += spc_modesense_long_blockdesc(&buf[length],
                                                                       blocks, block_size);
                        } else {
                                length += 3;
                                length += spc_modesense_blockdesc(&buf[length],
                                                                  blocks, block_size);
                        }
                } else {
                        length += spc_modesense_blockdesc(&buf[length], blocks,
                                                          block_size);
                }
        } else {
                if (ten)
                        length += 4;
                else
                        length += 1;
        }

        if (page == 0x3f) {
                if (subpage != 0x00 && subpage != 0xff) {
                        pr_warn("MODE_SENSE: Invalid subpage code: 0x%02x\n", subpage);
                        return TCM_INVALID_CDB_FIELD;
                }

                for (i = 0; i < ARRAY_SIZE(modesense_handlers); ++i) {
                        /*
                         * Tricky way to say all subpage 00h for
                         * subpage==0, all subpages for subpage==0xff
                         * (and we just checked above that those are
                         * the only two possibilities).
                         */
                        if ((modesense_handlers[i].subpage & ~subpage) == 0) {
                                ret = modesense_handlers[i].emulate(dev, pc, &buf[length]);
                                if (!ten && length + ret >= 255)
                                        break;
                                length += ret;
                        }
                }

                goto set_length;
        }

        for (i = 0; i < ARRAY_SIZE(modesense_handlers); ++i)
                if (modesense_handlers[i].page == page &&
                    modesense_handlers[i].subpage == subpage) {
                        length += modesense_handlers[i].emulate(dev, pc, &buf[length]);
                        goto set_length;
                }

        /*
         * We don't intend to implement:
         *  - obsolete page 03h "format parameters" (checked by Solaris)
         */
        if (page != 0x03)
                pr_err("MODE SENSE: unimplemented page/subpage: 0x%02x/0x%02x\n",
                       page, subpage);

        return TCM_UNKNOWN_MODE_PAGE;

set_length:
        if (ten)
                put_unaligned_be16(length - 2, buf);
        else
                buf[0] = length - 1;

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

        target_complete_cmd(cmd, GOOD);
        return 0;
}

static sense_reason_t spc_emulate_modeselect(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        char *cdb = cmd->t_task_cdb;
        bool ten = cdb[0] == MODE_SELECT_10;
        int off = ten ? 8 : 4;
        bool pf = !!(cdb[1] & 0x10);
        u8 page, subpage;
        unsigned char *buf;
        unsigned char tbuf[SE_MODE_PAGE_BUF];
        int length;
        int ret = 0;
        int i;

        if (!cmd->data_length) {
                target_complete_cmd(cmd, GOOD);
                return 0;
        }

        if (cmd->data_length < off + 2)
                return TCM_PARAMETER_LIST_LENGTH_ERROR;

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

        if (!pf) {
                ret = TCM_INVALID_CDB_FIELD;
                goto out;
        }

        page = buf[off] & 0x3f;
        subpage = buf[off] & 0x40 ? buf[off + 1] : 0;

        for (i = 0; i < ARRAY_SIZE(modesense_handlers); ++i)
                if (modesense_handlers[i].page == page &&
                    modesense_handlers[i].subpage == subpage) {
                        memset(tbuf, 0, SE_MODE_PAGE_BUF);
                        length = modesense_handlers[i].emulate(dev, 0, tbuf);
                        goto check_contents;
                }

        ret = TCM_UNKNOWN_MODE_PAGE;
        goto out;

check_contents:
        if (cmd->data_length < off + length) {
                ret = TCM_PARAMETER_LIST_LENGTH_ERROR;
                goto out;
        }

        if (memcmp(buf + off, tbuf, length))
                ret = TCM_INVALID_PARAMETER_LIST;

out:
        transport_kunmap_data_sg(cmd);

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

static sense_reason_t 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");
                return TCM_INVALID_CDB_FIELD;
        }

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

        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;
        }

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

        target_complete_cmd(cmd, GOOD);
        return 0;
}

sense_reason_t spc_emulate_report_luns(struct se_cmd *cmd)
{
        struct se_dev_entry *deve;
        struct se_session *sess = cmd->se_sess;
        unsigned char *buf;
        u32 lun_count = 0, offset = 8, i;

        if (cmd->data_length < 16) {
                pr_warn("REPORT LUNS 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;

        /*
         * If no struct se_session pointer is present, this struct se_cmd is
         * coming via a target_core_mod PASSTHROUGH op, and not through
         * a $FABRIC_MOD.  In that case, report LUN=0 only.
         */
        if (!sess) {
                int_to_scsilun(0, (struct scsi_lun *)&buf[offset]);
                lun_count = 1;
                goto done;
        }

        spin_lock_irq(&sess->se_node_acl->device_list_lock);
        for (i = 0; i < TRANSPORT_MAX_LUNS_PER_TPG; i++) {
                deve = sess->se_node_acl->device_list[i];
                if (!(deve->lun_flags & TRANSPORT_LUNFLAGS_INITIATOR_ACCESS))
                        continue;
                /*
                 * We determine the correct LUN LIST LENGTH even once we
                 * have reached the initial allocation length.
                 * See SPC2-R20 7.19.
                 */
                lun_count++;
                if ((offset + 8) > cmd->data_length)
                        continue;

                int_to_scsilun(deve->mapped_lun, (struct scsi_lun *)&buf[offset]);
                offset += 8;
        }
        spin_unlock_irq(&sess->se_node_acl->device_list_lock);

        /*
         * See SPC3 r07, page 159.
         */
done:
        lun_count *= 8;
        buf[0] = ((lun_count >> 24) & 0xff);
        buf[1] = ((lun_count >> 16) & 0xff);
        buf[2] = ((lun_count >> 8) & 0xff);
        buf[3] = (lun_count & 0xff);
        transport_kunmap_data_sg(cmd);

        target_complete_cmd(cmd, GOOD);
        return 0;
}
EXPORT_SYMBOL(spc_emulate_report_luns);

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

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

        switch (cdb[0]) {
        case MODE_SELECT:
                *size = cdb[4];
                cmd->execute_cmd = spc_emulate_modeselect;
                break;
        case MODE_SELECT_10:
                *size = (cdb[7] << 8) + cdb[8];
                cmd->execute_cmd = spc_emulate_modeselect;
                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:
                *size = (cdb[7] << 8) + cdb[8];
                cmd->execute_cmd = target_scsi3_emulate_pr_in;
                break;
        case PERSISTENT_RESERVE_OUT:
                *size = (cdb[7] << 8) + cdb[8];
                cmd->execute_cmd = target_scsi3_emulate_pr_out;
                break;
        case RELEASE:
        case RELEASE_10:
                if (cdb[0] == RELEASE_10)
                        *size = (cdb[7] << 8) | cdb[8];
                else
                        *size = cmd->data_length;

                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;

                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
                 */
                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 = spc_emulate_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
                 */
                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) {
                                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) {
                                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]);
                return TCM_UNSUPPORTED_SCSI_OPCODE;
        }

        return 0;
}
EXPORT_SYMBOL(spc_parse_cdb);