ext4: avoid potential hang in mpage_submit_io() when blocksize < pagesize

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / target / target_core_cdb.c

/*
 * CDB emulation for non-READ/WRITE commands.
 *
 * 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 <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/ctype.h>
#include <asm/unaligned.h>
#include <scsi/scsi.h>

#include <target/target_core_base.h>
#include <target/target_core_transport.h>
#include <target/target_core_fabric_ops.h>
#include "target_core_ua.h"

static void
target_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
target_emulate_inquiry_std(struct se_cmd *cmd)
{
        struct se_lun *lun = cmd->se_lun;
        struct se_device *dev = cmd->se_dev;
        struct se_portal_group *tpg = lun->lun_sep->sep_tpg;
        unsigned char *buf;

        /*
         * Make sure we at least have 6 bytes of INQUIRY response
         * payload going back for EVPD=0
         */
        if (cmd->data_length < 6) {
                pr_err("SCSI Inquiry payload length: %u"
                        " too small for EVPD=0\n", cmd->data_length);
                return -EINVAL;
        }

        buf = transport_kmap_first_data_page(cmd);

        if (dev == tpg->tpg_virt_lun0.lun_se_dev) {
                buf[0] = 0x3f; /* Not connected */
        } else {
                buf[0] = dev->transport->get_device_type(dev);
                if (buf[0] == TYPE_TAPE)
                        buf[1] = 0x80;
        }
        buf[2] = dev->transport->get_device_rev(dev);

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

        if (cmd->data_length < 8) {
                buf[4] = 1; /* Set additional length to 1 */
                goto out;
        }

        buf[7] = 0x32; /* Sync=1 and CmdQue=1 */

        /*
         * Do not include vendor, product, reversion info in INQUIRY
         * response payload for cdbs with a small allocation length.
         */
        if (cmd->data_length < 36) {
                buf[4] = 3; /* Set additional length to 3 */
                goto out;
        }

        snprintf((unsigned char *)&buf[8], 8, "LIO-ORG");
        snprintf((unsigned char *)&buf[16], 16, "%s",
                 &dev->se_sub_dev->t10_wwn.model[0]);
        snprintf((unsigned char *)&buf[32], 4, "%s",
                 &dev->se_sub_dev->t10_wwn.revision[0]);
        buf[4] = 31; /* Set additional length to 31 */

out:
        transport_kunmap_first_data_page(cmd);
        return 0;
}

/* unit serial number */
static int
target_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[0]);
                unit_serial_len++; /* For NULL Terminator */

                if (((len + 4) + unit_serial_len) > cmd->data_length) {
                        len += unit_serial_len;
                        buf[2] = ((len >> 8) & 0xff);
                        buf[3] = (len & 0xff);
                        return 0;
                }
                len += sprintf((unsigned char *)&buf[4], "%s",
                        &dev->se_sub_dev->t10_wwn.unit_serial[0]);
                len++; /* Extra Byte for NULL Terminator */
                buf[3] = len;
        }
        return 0;
}

static void
target_parse_naa_6h_vendor_specific(struct se_device *dev, unsigned char *buf_off)
{
        unsigned char *p = &dev->se_sub_dev->t10_wwn.unit_serial[0];
        unsigned char *buf = buf_off;
        int cnt = 0, next = 1;
        /*
         * 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.
         */
        while (*p != '\0') {
                if (cnt >= 13)
                        break;
                if (!isxdigit(*p)) {
                        p++;
                        continue;
                }
                if (next != 0) {
                        buf[cnt++] |= hex_to_bin(*p++);
                        next = 0;
                } else {
                        buf[cnt] = hex_to_bin(*p++) << 4;
                        next = 1;
                }
        }
}

/*
 * Device identification VPD, for a complete list of
 * DESIGNATOR TYPEs see spc4r17 Table 459.
 */
static int
target_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;

        if (off + 20 > cmd->data_length)
                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
         */
        target_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 */

                if ((len + (id_len + 4) +
                    (prod_len + unit_serial_len)) >
                                cmd->data_length) {
                        len += (prod_len + unit_serial_len);
                        goto check_port;
                }
                id_len += sprintf((unsigned char *)&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((unsigned char *)&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
         */
check_port:
        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
                 */
                if (((len + 4) + 8) > cmd->data_length) {
                        len += 8;
                        goto check_tpgi;
                }
                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
                 */
check_tpgi:
                if (dev->se_sub_dev->t10_alua.alua_type !=
                                SPC3_ALUA_EMULATED)
                        goto check_scsi_name;

                if (((len + 4) + 8) > cmd->data_length) {
                        len += 8;
                        goto check_lu_gp;
                }
                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:
                if (((len + 4) + 8) > cmd->data_length) {
                        len += 8;
                        goto check_scsi_name;
                }
                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;

                if (((len + 4) + scsi_name_len) > cmd->data_length) {
                        len += scsi_name_len;
                        goto set_len;
                }
                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);
        }
set_len:
        buf[2] = ((len >> 8) & 0xff);
        buf[3] = (len & 0xff); /* Page Length for VPD 0x83 */
        return 0;
}

/* Extended INQUIRY Data VPD Page */
static int
target_emulate_evpd_86(struct se_cmd *cmd, unsigned char *buf)
{
        if (cmd->data_length < 60)
                return 0;

        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
target_emulate_evpd_b0(struct se_cmd *cmd, unsigned char *buf)
{
        struct se_device *dev = cmd->se_dev;
        int have_tp = 0;

        /*
         * Following sbc3r22 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;

        if (cmd->data_length < (0x10 + 4)) {
                pr_debug("Received data_length: %u"
                        " too small for EVPD 0xb0\n",
                        cmd->data_length);
                return -EINVAL;
        }

        if (have_tp && cmd->data_length < (0x3c + 4)) {
                pr_debug("Received data_length: %u"
                        " too small for TPE=1 EVPD 0xb0\n",
                        cmd->data_length);
                have_tp = 0;
        }

        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
         */
        put_unaligned_be32(dev->se_sub_dev->se_dev_attrib.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 or the initiator sent a too
         * short buffer.
         */
        if (!have_tp || cmd->data_length < (0x3c + 4))
                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
target_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;

        if (cmd->data_length >= 5 &&
            dev->se_sub_dev->se_dev_attrib.is_nonrot)
                buf[5] = 1;

        return 0;
}

/* Thin Provisioning VPD */
static int
target_emulate_evpd_b2(struct se_cmd *cmd, unsigned char *buf)
{
        struct se_device *dev = cmd->se_dev;

        /*
         * From sbc3r22 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
target_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 = target_emulate_evpd_00 },
        { .page = 0x80, .emulate = target_emulate_evpd_80 },
        { .page = 0x83, .emulate = target_emulate_evpd_83 },
        { .page = 0x86, .emulate = target_emulate_evpd_86 },
        { .page = 0xb0, .emulate = target_emulate_evpd_b0 },
        { .page = 0xb1, .emulate = target_emulate_evpd_b1 },
        { .page = 0xb2, .emulate = target_emulate_evpd_b2 },
};

/* supported vital product data pages */
static int
target_emulate_evpd_00(struct se_cmd *cmd, unsigned char *buf)
{
        int p;

        if (cmd->data_length < 8)
                return 0;
        /*
         * 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 < min_t(int, ARRAY_SIZE(evpd_handlers),
                                      cmd->data_length - 4); ++p)
                        buf[p + 4] = evpd_handlers[p].page;
        }

        return 0;
}

static int
target_emulate_inquiry(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        unsigned char *buf;
        unsigned char *cdb = cmd->t_task_cdb;
        int p, ret;

        if (!(cdb[1] & 0x1))
                return target_emulate_inquiry_std(cmd);

        /*
         * Make sure we at least have 4 bytes of INQUIRY response
         * payload for 0x00 going back for EVPD=1.  Note that 0x80
         * and 0x83 will check for enough payload data length and
         * jump to set_len: label when there is not enough inquiry EVPD
         * payload length left for the next outgoing EVPD metadata
         */
        if (cmd->data_length < 4) {
                pr_err("SCSI Inquiry payload length: %u"
                        " too small for EVPD=1\n", cmd->data_length);
                return -EINVAL;
        }

        buf = transport_kmap_first_data_page(cmd);

        buf[0] = dev->transport->get_device_type(dev);

        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);
                        transport_kunmap_first_data_page(cmd);
                        return ret;
                }

        transport_kunmap_first_data_page(cmd);
        pr_err("Unknown VPD Code: 0x%02x\n", cdb[2]);
        return -EINVAL;
}

static int
target_emulate_readcapacity(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        unsigned char *buf;
        unsigned long long blocks_long = dev->transport->get_blocks(dev);
        u32 blocks;

        if (blocks_long >= 0x00000000ffffffff)
                blocks = 0xffffffff;
        else
                blocks = (u32)blocks_long;

        buf = transport_kmap_first_data_page(cmd);

        buf[0] = (blocks >> 24) & 0xff;
        buf[1] = (blocks >> 16) & 0xff;
        buf[2] = (blocks >> 8) & 0xff;
        buf[3] = blocks & 0xff;
        buf[4] = (dev->se_sub_dev->se_dev_attrib.block_size >> 24) & 0xff;
        buf[5] = (dev->se_sub_dev->se_dev_attrib.block_size >> 16) & 0xff;
        buf[6] = (dev->se_sub_dev->se_dev_attrib.block_size >> 8) & 0xff;
        buf[7] = dev->se_sub_dev->se_dev_attrib.block_size & 0xff;
        /*
         * Set max 32-bit blocks to signal SERVICE ACTION READ_CAPACITY_16
        */
        if (dev->se_sub_dev->se_dev_attrib.emulate_tpu || dev->se_sub_dev->se_dev_attrib.emulate_tpws)
                put_unaligned_be32(0xFFFFFFFF, &buf[0]);

        transport_kunmap_first_data_page(cmd);

        return 0;
}

static int
target_emulate_readcapacity_16(struct se_cmd *cmd)
{
        struct se_device *dev = cmd->se_dev;
        unsigned char *buf;
        unsigned long long blocks = dev->transport->get_blocks(dev);

        buf = transport_kmap_first_data_page(cmd);

        buf[0] = (blocks >> 56) & 0xff;
        buf[1] = (blocks >> 48) & 0xff;
        buf[2] = (blocks >> 40) & 0xff;
        buf[3] = (blocks >> 32) & 0xff;
        buf[4] = (blocks >> 24) & 0xff;
        buf[5] = (blocks >> 16) & 0xff;
        buf[6] = (blocks >> 8) & 0xff;
        buf[7] = blocks & 0xff;
        buf[8] = (dev->se_sub_dev->se_dev_attrib.block_size >> 24) & 0xff;
        buf[9] = (dev->se_sub_dev->se_dev_attrib.block_size >> 16) & 0xff;
        buf[10] = (dev->se_sub_dev->se_dev_attrib.block_size >> 8) & 0xff;
        buf[11] = dev->se_sub_dev->se_dev_attrib.block_size & 0xff;
        /*
         * Set Thin Provisioning Enable bit following sbc3r22 in section
         * READ CAPACITY (16) byte 14 if emulate_tpu or emulate_tpws is enabled.
         */
        if (dev->se_sub_dev->se_dev_attrib.emulate_tpu || dev->se_sub_dev->se_dev_attrib.emulate_tpws)
                buf[14] = 0x80;

        transport_kunmap_first_data_page(cmd);

        return 0;
}

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

        return 12;
}

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

static int
target_emulate_modesense(struct se_cmd *cmd, int ten)
{
        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 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 = target_modesense_rwrecovery(&buf[offset]);
                break;
        case 0x08:
                length = target_modesense_caching(dev, &buf[offset]);
                break;
        case 0x0a:
                length = target_modesense_control(dev, &buf[offset]);
                break;
        case 0x3f:
                length = target_modesense_rwrecovery(&buf[offset]);
                length += target_modesense_caching(dev, &buf[offset+length]);
                length += target_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]);
                return PYX_TRANSPORT_UNKNOWN_MODE_PAGE;
        }
        offset += length;

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

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

                if ((offset + 2) > cmd->data_length)
                        offset = cmd->data_length;

        } else {
                offset -= 1;
                buf[0] = offset & 0xff;

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

                if ((offset + 1) > cmd->data_length)
                        offset = cmd->data_length;
        }

        rbuf = transport_kmap_first_data_page(cmd);
        memcpy(rbuf, buf, offset);
        transport_kunmap_first_data_page(cmd);

        return 0;
}

static int
target_emulate_request_sense(struct se_cmd *cmd)
{
        unsigned char *cdb = cmd->t_task_cdb;
        unsigned char *buf;
        u8 ua_asc = 0, ua_ascq = 0;
        int err = 0;

        if (cdb[1] & 0x01) {
                pr_err("REQUEST_SENSE description emulation not"
                        " supported\n");
                return PYX_TRANSPORT_INVALID_CDB_FIELD;
        }

        buf = transport_kmap_first_data_page(cmd);

        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;
                /*
                 * Make sure request data length is enough for additional
                 * sense data.
                 */
                if (cmd->data_length <= 18) {
                        buf[7] = 0x00;
                        err = -EINVAL;
                        goto end;
                }
                /*
                 * 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;
                /*
                 * Make sure request data length is enough for additional
                 * sense data.
                 */
                if (cmd->data_length <= 18) {
                        buf[7] = 0x00;
                        err = -EINVAL;
                        goto end;
                }
                /*
                 * NO ADDITIONAL SENSE INFORMATION
                 */
                buf[SPC_ASC_KEY_OFFSET] = 0x00;
                buf[7] = 0x0A;
        }

end:
        transport_kunmap_first_data_page(cmd);

        return 0;
}

/*
 * Used for TCM/IBLOCK and TCM/FILEIO for block/blk-lib.c level discard support.
 * Note this is not used for TCM/pSCSI passthrough
 */
static int
target_emulate_unmap(struct se_task *task)
{
        struct se_cmd *cmd = task->task_se_cmd;
        struct se_device *dev = cmd->se_dev;
        unsigned char *buf, *ptr = NULL;
        unsigned char *cdb = &cmd->t_task_cdb[0];
        sector_t lba;
        unsigned int size = cmd->data_length, range;
        int ret = 0, offset;
        unsigned short dl, bd_dl;

        /* First UNMAP block descriptor starts at 8 byte offset */
        offset = 8;
        size -= 8;
        dl = get_unaligned_be16(&cdb[0]);
        bd_dl = get_unaligned_be16(&cdb[2]);

        buf = transport_kmap_first_data_page(cmd);

        ptr = &buf[offset];
        pr_debug("UNMAP: Sub: %s Using dl: %hu bd_dl: %hu size: %hu"
                " ptr: %p\n", dev->transport->name, dl, bd_dl, size, ptr);

        while (size) {
                lba = get_unaligned_be64(&ptr[0]);
                range = get_unaligned_be32(&ptr[8]);
                pr_debug("UNMAP: Using lba: %llu and range: %u\n",
                                 (unsigned long long)lba, range);

                ret = dev->transport->do_discard(dev, lba, range);
                if (ret < 0) {
                        pr_err("blkdev_issue_discard() failed: %d\n",
                                        ret);
                        goto err;
                }

                ptr += 16;
                size -= 16;
        }

err:
        transport_kunmap_first_data_page(cmd);

        return ret;
}

/*
 * Used for TCM/IBLOCK and TCM/FILEIO for block/blk-lib.c level discard support.
 * Note this is not used for TCM/pSCSI passthrough
 */
static int
target_emulate_write_same(struct se_task *task, u32 num_blocks)
{
        struct se_cmd *cmd = task->task_se_cmd;
        struct se_device *dev = cmd->se_dev;
        sector_t range;
        sector_t lba = cmd->t_task_lba;
        int ret;
        /*
         * Use the explicit range when non zero is supplied, otherwise calculate
         * the remaining range based on ->get_blocks() - starting LBA.
         */
        if (num_blocks != 0)
                range = num_blocks;
        else
                range = (dev->transport->get_blocks(dev) - lba);

        pr_debug("WRITE_SAME UNMAP: LBA: %llu Range: %llu\n",
                 (unsigned long long)lba, (unsigned long long)range);

        ret = dev->transport->do_discard(dev, lba, range);
        if (ret < 0) {
                pr_debug("blkdev_issue_discard() failed for WRITE_SAME\n");
                return ret;
        }

        return 0;
}

int
transport_emulate_control_cdb(struct se_task *task)
{
        struct se_cmd *cmd = task->task_se_cmd;
        struct se_device *dev = cmd->se_dev;
        unsigned short service_action;
        int ret = 0;

        switch (cmd->t_task_cdb[0]) {
        case INQUIRY:
                ret = target_emulate_inquiry(cmd);
                break;
        case READ_CAPACITY:
                ret = target_emulate_readcapacity(cmd);
                break;
        case MODE_SENSE:
                ret = target_emulate_modesense(cmd, 0);
                break;
        case MODE_SENSE_10:
                ret = target_emulate_modesense(cmd, 1);
                break;
        case SERVICE_ACTION_IN:
                switch (cmd->t_task_cdb[1] & 0x1f) {
                case SAI_READ_CAPACITY_16:
                        ret = target_emulate_readcapacity_16(cmd);
                        break;
                default:
                        pr_err("Unsupported SA: 0x%02x\n",
                                cmd->t_task_cdb[1] & 0x1f);
                        return PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
                }
                break;
        case REQUEST_SENSE:
                ret = target_emulate_request_sense(cmd);
                break;
        case UNMAP:
                if (!dev->transport->do_discard) {
                        pr_err("UNMAP emulation not supported for: %s\n",
                                        dev->transport->name);
                        return PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
                }
                ret = target_emulate_unmap(task);
                break;
        case WRITE_SAME:
                if (!dev->transport->do_discard) {
                        pr_err("WRITE_SAME emulation not supported"
                                        " for: %s\n", dev->transport->name);
                        return PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
                }
                ret = target_emulate_write_same(task,
                                get_unaligned_be16(&cmd->t_task_cdb[7]));
                break;
        case WRITE_SAME_16:
                if (!dev->transport->do_discard) {
                        pr_err("WRITE_SAME_16 emulation not supported"
                                        " for: %s\n", dev->transport->name);
                        return PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
                }
                ret = target_emulate_write_same(task,
                                get_unaligned_be32(&cmd->t_task_cdb[10]));
                break;
        case VARIABLE_LENGTH_CMD:
                service_action =
                        get_unaligned_be16(&cmd->t_task_cdb[8]);
                switch (service_action) {
                case WRITE_SAME_32:
                        if (!dev->transport->do_discard) {
                                pr_err("WRITE_SAME_32 SA emulation not"
                                        " supported for: %s\n",
                                        dev->transport->name);
                                return PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
                        }
                        ret = target_emulate_write_same(task,
                                get_unaligned_be32(&cmd->t_task_cdb[28]));
                        break;
                default:
                        pr_err("Unsupported VARIABLE_LENGTH_CMD SA:"
                                        " 0x%02x\n", service_action);
                        break;
                }
                break;
        case SYNCHRONIZE_CACHE:
        case 0x91: /* SYNCHRONIZE_CACHE_16: */
                if (!dev->transport->do_sync_cache) {
                        pr_err("SYNCHRONIZE_CACHE emulation not supported"
                                " for: %s\n", dev->transport->name);
                        return PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
                }
                dev->transport->do_sync_cache(task);
                break;
        case ALLOW_MEDIUM_REMOVAL:
        case ERASE:
        case REZERO_UNIT:
        case SEEK_10:
        case SPACE:
        case START_STOP:
        case TEST_UNIT_READY:
        case VERIFY:
        case WRITE_FILEMARKS:
                break;
        default:
                pr_err("Unsupported SCSI Opcode: 0x%02x for %s\n",
                        cmd->t_task_cdb[0], dev->transport->name);
                return PYX_TRANSPORT_UNKNOWN_SAM_OPCODE;
        }

        if (ret < 0)
                return ret;
        /*
         * Handle the successful completion here unless a caller
         * has explictly requested an asychronous completion.
         */
        if (!(cmd->se_cmd_flags & SCF_EMULATE_CDB_ASYNC)) {
                task->task_scsi_status = GOOD;
                transport_complete_task(task, 1);
        }

        return PYX_TRANSPORT_SENT_TO_TRANSPORT;
}