tcm_vhost.c

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/*******************************************************************************
 * Vhost kernel TCM fabric driver for virtio SCSI initiators
 *
 * (C) Copyright 2010-2012 RisingTide Systems LLC.
 * (C) Copyright 2010-2012 IBM Corp.
 *
 * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
 *
 * Authors: Nicholas A. Bellinger <[email protected]>
 *          Stefan Hajnoczi <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 ****************************************************************************/

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <generated/utsrelease.h>
#include <linux/utsname.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/configfs.h>
#include <linux/ctype.h>
#include <linux/compat.h>
#include <linux/eventfd.h>
#include <linux/vhost.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <asm/unaligned.h>
#include <scsi/scsi.h>
#include <scsi/scsi_tcq.h>
#include <target/target_core_base.h>
#include <target/target_core_fabric.h>
#include <target/target_core_fabric_configfs.h>
#include <target/target_core_configfs.h>
#include <target/configfs_macros.h>
#include <linux/vhost.h>
#include <linux/virtio_net.h> /* TODO vhost.h currently depends on this */
#include <linux/virtio_scsi.h>

#include "vhost.c"
#include "vhost.h"
#include "tcm_vhost.h"

enum {
    VHOST_SCSI_VQ_CTL = 0,
    VHOST_SCSI_VQ_EVT = 1,
    VHOST_SCSI_VQ_IO = 2,
};

struct vhost_scsi {
    struct tcm_vhost_tpg *vs_tpg;   /* Protected by vhost_scsi->dev.mutex */
    struct vhost_dev dev;
    struct vhost_virtqueue vqs[3];

    struct vhost_work vs_completion_work; /* cmd completion work item */
    struct list_head vs_completion_list;  /* cmd completion queue */
    spinlock_t vs_completion_lock;        /* protects s_completion_list */
};

/* Local pointer to allocated TCM configfs fabric module */
static struct target_fabric_configfs *tcm_vhost_fabric_configfs;

static struct workqueue_struct *tcm_vhost_workqueue;

/* Global spinlock to protect tcm_vhost TPG list for vhost IOCTL access */
static DEFINE_MUTEX(tcm_vhost_mutex);
static LIST_HEAD(tcm_vhost_list);

static int tcm_vhost_check_true(struct se_portal_group *se_tpg)
{
    return 1;
}

static int tcm_vhost_check_false(struct se_portal_group *se_tpg)
{
    return 0;
}

static char *tcm_vhost_get_fabric_name(void)
{
    return "vhost";
}

static u8 tcm_vhost_get_fabric_proto_ident(struct se_portal_group *se_tpg)
{
    struct tcm_vhost_tpg *tpg = container_of(se_tpg,
                struct tcm_vhost_tpg, se_tpg);
    struct tcm_vhost_tport *tport = tpg->tport;

    switch (tport->tport_proto_id) {
    case SCSI_PROTOCOL_SAS:
        return sas_get_fabric_proto_ident(se_tpg);
    case SCSI_PROTOCOL_FCP:
        return fc_get_fabric_proto_ident(se_tpg);
    case SCSI_PROTOCOL_ISCSI:
        return iscsi_get_fabric_proto_ident(se_tpg);
    default:
        pr_err("Unknown tport_proto_id: 0x%02x, using"
            " SAS emulation\n", tport->tport_proto_id);
        break;
    }

    return sas_get_fabric_proto_ident(se_tpg);
}

static char *tcm_vhost_get_fabric_wwn(struct se_portal_group *se_tpg)
{
    struct tcm_vhost_tpg *tpg = container_of(se_tpg,
                struct tcm_vhost_tpg, se_tpg);
    struct tcm_vhost_tport *tport = tpg->tport;

    return &tport->tport_name[0];
}

static u16 tcm_vhost_get_tag(struct se_portal_group *se_tpg)
{
    struct tcm_vhost_tpg *tpg = container_of(se_tpg,
                struct tcm_vhost_tpg, se_tpg);
    return tpg->tport_tpgt;
}

static u32 tcm_vhost_get_default_depth(struct se_portal_group *se_tpg)
{
    return 1;
}

static u32 tcm_vhost_get_pr_transport_id(struct se_portal_group *se_tpg,
    struct se_node_acl *se_nacl,
    struct t10_pr_registration *pr_reg,
    int *format_code,
    unsigned char *buf)
{
    struct tcm_vhost_tpg *tpg = container_of(se_tpg,
                struct tcm_vhost_tpg, se_tpg);
    struct tcm_vhost_tport *tport = tpg->tport;

    switch (tport->tport_proto_id) {
    case SCSI_PROTOCOL_SAS:
        return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
                    format_code, buf);
    case SCSI_PROTOCOL_FCP:
        return fc_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
                    format_code, buf);
    case SCSI_PROTOCOL_ISCSI:
        return iscsi_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
                    format_code, buf);
    default:
        pr_err("Unknown tport_proto_id: 0x%02x, using"
            " SAS emulation\n", tport->tport_proto_id);
        break;
    }

    return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
            format_code, buf);
}

static u32 tcm_vhost_get_pr_transport_id_len(struct se_portal_group *se_tpg,
    struct se_node_acl *se_nacl,
    struct t10_pr_registration *pr_reg,
    int *format_code)
{
    struct tcm_vhost_tpg *tpg = container_of(se_tpg,
                struct tcm_vhost_tpg, se_tpg);
    struct tcm_vhost_tport *tport = tpg->tport;

    switch (tport->tport_proto_id) {
    case SCSI_PROTOCOL_SAS:
        return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
                    format_code);
    case SCSI_PROTOCOL_FCP:
        return fc_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
                    format_code);
    case SCSI_PROTOCOL_ISCSI:
        return iscsi_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
                    format_code);
    default:
        pr_err("Unknown tport_proto_id: 0x%02x, using"
            " SAS emulation\n", tport->tport_proto_id);
        break;
    }

    return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
            format_code);
}

static char *tcm_vhost_parse_pr_out_transport_id(struct se_portal_group *se_tpg,
    const char *buf,
    u32 *out_tid_len,
    char **port_nexus_ptr)
{
    struct tcm_vhost_tpg *tpg = container_of(se_tpg,
                struct tcm_vhost_tpg, se_tpg);
    struct tcm_vhost_tport *tport = tpg->tport;

    switch (tport->tport_proto_id) {
    case SCSI_PROTOCOL_SAS:
        return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
                    port_nexus_ptr);
    case SCSI_PROTOCOL_FCP:
        return fc_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
                    port_nexus_ptr);
    case SCSI_PROTOCOL_ISCSI:
        return iscsi_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
                    port_nexus_ptr);
    default:
        pr_err("Unknown tport_proto_id: 0x%02x, using"
            " SAS emulation\n", tport->tport_proto_id);
        break;
    }

    return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
            port_nexus_ptr);
}

static struct se_node_acl *tcm_vhost_alloc_fabric_acl(
    struct se_portal_group *se_tpg)
{
    struct tcm_vhost_nacl *nacl;

    nacl = kzalloc(sizeof(struct tcm_vhost_nacl), GFP_KERNEL);
    if (!nacl) {
        pr_err("Unable to alocate struct tcm_vhost_nacl\n");
        return NULL;
    }

    return &nacl->se_node_acl;
}

static void tcm_vhost_release_fabric_acl(struct se_portal_group *se_tpg,
    struct se_node_acl *se_nacl)
{
    struct tcm_vhost_nacl *nacl = container_of(se_nacl,
            struct tcm_vhost_nacl, se_node_acl);
    kfree(nacl);
}

static u32 tcm_vhost_tpg_get_inst_index(struct se_portal_group *se_tpg)
{
    return 1;
}

static void tcm_vhost_release_cmd(struct se_cmd *se_cmd)
{
    return;
}

static int tcm_vhost_shutdown_session(struct se_session *se_sess)
{
    return 0;
}

static void tcm_vhost_close_session(struct se_session *se_sess)
{
    return;
}

static u32 tcm_vhost_sess_get_index(struct se_session *se_sess)
{
    return 0;
}

static int tcm_vhost_write_pending(struct se_cmd *se_cmd)
{
    /* Go ahead and process the write immediately */
    target_execute_cmd(se_cmd);
    return 0;
}

static int tcm_vhost_write_pending_status(struct se_cmd *se_cmd)
{
    return 0;
}

static void tcm_vhost_set_default_node_attrs(struct se_node_acl *nacl)
{
    return;
}

static u32 tcm_vhost_get_task_tag(struct se_cmd *se_cmd)
{
    return 0;
}

static int tcm_vhost_get_cmd_state(struct se_cmd *se_cmd)
{
    return 0;
}

static void vhost_scsi_complete_cmd(struct tcm_vhost_cmd *tv_cmd)
{
    struct vhost_scsi *vs = tv_cmd->tvc_vhost;

    spin_lock_bh(&vs->vs_completion_lock);
    list_add_tail(&tv_cmd->tvc_completion_list, &vs->vs_completion_list);
    spin_unlock_bh(&vs->vs_completion_lock);

    vhost_work_queue(&vs->dev, &vs->vs_completion_work);
}

static int tcm_vhost_queue_data_in(struct se_cmd *se_cmd)
{
    struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
                struct tcm_vhost_cmd, tvc_se_cmd);
    vhost_scsi_complete_cmd(tv_cmd);
    return 0;
}

static int tcm_vhost_queue_status(struct se_cmd *se_cmd)
{
    struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
                struct tcm_vhost_cmd, tvc_se_cmd);
    vhost_scsi_complete_cmd(tv_cmd);
    return 0;
}

static int tcm_vhost_queue_tm_rsp(struct se_cmd *se_cmd)
{
    return 0;
}

static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *tv_cmd)
{
    struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;

    /* TODO locking against target/backend threads? */
    transport_generic_free_cmd(se_cmd, 1);

    if (tv_cmd->tvc_sgl_count) {
        u32 i;
        for (i = 0; i < tv_cmd->tvc_sgl_count; i++)
            put_page(sg_page(&tv_cmd->tvc_sgl[i]));

        kfree(tv_cmd->tvc_sgl);
    }

    kfree(tv_cmd);
}

/* Dequeue a command from the completion list */
static struct tcm_vhost_cmd *vhost_scsi_get_cmd_from_completion(
    struct vhost_scsi *vs)
{
    struct tcm_vhost_cmd *tv_cmd = NULL;

    spin_lock_bh(&vs->vs_completion_lock);
    if (list_empty(&vs->vs_completion_list)) {
        spin_unlock_bh(&vs->vs_completion_lock);
        return NULL;
    }

    list_for_each_entry(tv_cmd, &vs->vs_completion_list,
                tvc_completion_list) {
        list_del(&tv_cmd->tvc_completion_list);
        break;
    }
    spin_unlock_bh(&vs->vs_completion_lock);
    return tv_cmd;
}

/* Fill in status and signal that we are done processing this command
 *
 * This is scheduled in the vhost work queue so we are called with the owner
 * process mm and can access the vring.
 */
static void vhost_scsi_complete_cmd_work(struct vhost_work *work)
{
    struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
                    vs_completion_work);
    struct tcm_vhost_cmd *tv_cmd;

    while ((tv_cmd = vhost_scsi_get_cmd_from_completion(vs))) {
        struct virtio_scsi_cmd_resp v_rsp;
        struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
        int ret;

        pr_debug("%s tv_cmd %p resid %u status %#02x\n", __func__,
            tv_cmd, se_cmd->residual_count, se_cmd->scsi_status);

        memset(&v_rsp, 0, sizeof(v_rsp));
        v_rsp.resid = se_cmd->residual_count;
        /* TODO is status_qualifier field needed? */
        v_rsp.status = se_cmd->scsi_status;
        v_rsp.sense_len = se_cmd->scsi_sense_length;
        memcpy(v_rsp.sense, tv_cmd->tvc_sense_buf,
               v_rsp.sense_len);
        ret = copy_to_user(tv_cmd->tvc_resp, &v_rsp, sizeof(v_rsp));
        if (likely(ret == 0))
            vhost_add_used(&vs->vqs[2], tv_cmd->tvc_vq_desc, 0);
        else
            pr_err("Faulted on virtio_scsi_cmd_resp\n");

        vhost_scsi_free_cmd(tv_cmd);
    }

    vhost_signal(&vs->dev, &vs->vqs[2]);
}

static struct tcm_vhost_cmd *vhost_scsi_allocate_cmd(
    struct tcm_vhost_tpg *tv_tpg,
    struct virtio_scsi_cmd_req *v_req,
    u32 exp_data_len,
    int data_direction)
{
    struct tcm_vhost_cmd *tv_cmd;
    struct tcm_vhost_nexus *tv_nexus;
    struct se_session *se_sess;

    tv_nexus = tv_tpg->tpg_nexus;
    if (!tv_nexus) {
        pr_err("Unable to locate active struct tcm_vhost_nexus\n");
        return ERR_PTR(-EIO);
    }
    se_sess = tv_nexus->tvn_se_sess;

    tv_cmd = kzalloc(sizeof(struct tcm_vhost_cmd), GFP_ATOMIC);
    if (!tv_cmd) {
        pr_err("Unable to allocate struct tcm_vhost_cmd\n");
        return ERR_PTR(-ENOMEM);
    }
    INIT_LIST_HEAD(&tv_cmd->tvc_completion_list);
    tv_cmd->tvc_tag = v_req->tag;
    tv_cmd->tvc_task_attr = v_req->task_attr;
    tv_cmd->tvc_exp_data_len = exp_data_len;
    tv_cmd->tvc_data_direction = data_direction;
    tv_cmd->tvc_nexus = tv_nexus;

    return tv_cmd;
}

/*
 * Map a user memory range into a scatterlist
 *
 * Returns the number of scatterlist entries used or -errno on error.
 */
static int vhost_scsi_map_to_sgl(struct scatterlist *sgl,
    unsigned int sgl_count, void __user *ptr, size_t len, int write)
{
    struct scatterlist *sg = sgl;
    unsigned int npages = 0;
    int ret;

    while (len > 0) {
        struct page *page;
        unsigned int offset = (uintptr_t)ptr & ~PAGE_MASK;
        unsigned int nbytes = min_t(unsigned int,
                PAGE_SIZE - offset, len);

        if (npages == sgl_count) {
            ret = -ENOBUFS;
            goto err;
        }

        ret = get_user_pages_fast((unsigned long)ptr, 1, write, &page);
        BUG_ON(ret == 0); /* we should either get our page or fail */
        if (ret < 0)
            goto err;

        sg_set_page(sg, page, nbytes, offset);
        ptr += nbytes;
        len -= nbytes;
        sg++;
        npages++;
    }
    return npages;

err:
    /* Put pages that we hold */
    for (sg = sgl; sg != &sgl[npages]; sg++)
        put_page(sg_page(sg));
    return ret;
}

static int vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *tv_cmd,
    struct iovec *iov, unsigned int niov, int write)
{
    int ret;
    unsigned int i;
    u32 sgl_count;
    struct scatterlist *sg;

    /*
     * Find out how long sglist needs to be
     */
    sgl_count = 0;
    for (i = 0; i < niov; i++) {
        sgl_count += (((uintptr_t)iov[i].iov_base + iov[i].iov_len +
                PAGE_SIZE - 1) >> PAGE_SHIFT) -
                ((uintptr_t)iov[i].iov_base >> PAGE_SHIFT);
    }
    /* TODO overflow checking */

    sg = kmalloc(sizeof(tv_cmd->tvc_sgl[0]) * sgl_count, GFP_ATOMIC);
    if (!sg)
        return -ENOMEM;
    pr_debug("%s sg %p sgl_count %u is_err %d\n", __func__,
           sg, sgl_count, !sg);
    sg_init_table(sg, sgl_count);

    tv_cmd->tvc_sgl = sg;
    tv_cmd->tvc_sgl_count = sgl_count;

    pr_debug("Mapping %u iovecs for %u pages\n", niov, sgl_count);
    for (i = 0; i < niov; i++) {
        ret = vhost_scsi_map_to_sgl(sg, sgl_count, iov[i].iov_base,
                    iov[i].iov_len, write);
        if (ret < 0) {
            for (i = 0; i < tv_cmd->tvc_sgl_count; i++)
                put_page(sg_page(&tv_cmd->tvc_sgl[i]));
            kfree(tv_cmd->tvc_sgl);
            tv_cmd->tvc_sgl = NULL;
            tv_cmd->tvc_sgl_count = 0;
            return ret;
        }

        sg += ret;
        sgl_count -= ret;
    }
    return 0;
}

static void tcm_vhost_submission_work(struct work_struct *work)
{
    struct tcm_vhost_cmd *tv_cmd =
        container_of(work, struct tcm_vhost_cmd, work);
    struct tcm_vhost_nexus *tv_nexus;
    struct se_cmd *se_cmd = &tv_cmd->tvc_se_cmd;
    struct scatterlist *sg_ptr, *sg_bidi_ptr = NULL;
    int rc, sg_no_bidi = 0;

    if (tv_cmd->tvc_sgl_count) {
        sg_ptr = tv_cmd->tvc_sgl;
        /*
         * For BIDI commands, pass in the extra READ buffer
         * to transport_generic_map_mem_to_cmd() below..
         */
/* FIXME: Fix BIDI operation in tcm_vhost_submission_work() */
#if 0
        if (se_cmd->se_cmd_flags & SCF_BIDI) {
            sg_bidi_ptr = NULL;
            sg_no_bidi = 0;
        }
#endif
    } else {
        sg_ptr = NULL;
    }
    tv_nexus = tv_cmd->tvc_nexus;

    rc = target_submit_cmd_map_sgls(se_cmd, tv_nexus->tvn_se_sess,
            tv_cmd->tvc_cdb, &tv_cmd->tvc_sense_buf[0],
            tv_cmd->tvc_lun, tv_cmd->tvc_exp_data_len,
            tv_cmd->tvc_task_attr, tv_cmd->tvc_data_direction,
            0, sg_ptr, tv_cmd->tvc_sgl_count,
            sg_bidi_ptr, sg_no_bidi);
    if (rc < 0) {
        transport_send_check_condition_and_sense(se_cmd,
                TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE, 0);
        transport_generic_free_cmd(se_cmd, 0);
    }
}

static void vhost_scsi_handle_vq(struct vhost_scsi *vs)
{
    struct vhost_virtqueue *vq = &vs->vqs[2];
    struct virtio_scsi_cmd_req v_req;
    struct tcm_vhost_tpg *tv_tpg;
    struct tcm_vhost_cmd *tv_cmd;
    u32 exp_data_len, data_first, data_num, data_direction;
    unsigned out, in, i;
    int head, ret;

    /* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
    tv_tpg = vs->vs_tpg;
    if (unlikely(!tv_tpg)) {
        pr_err("%s endpoint not set\n", __func__);
        return;
    }

    mutex_lock(&vq->mutex);
    vhost_disable_notify(&vs->dev, vq);

    for (;;) {
        head = vhost_get_vq_desc(&vs->dev, vq, vq->iov,
                    ARRAY_SIZE(vq->iov), &out, &in,
                    NULL, NULL);
        pr_debug("vhost_get_vq_desc: head: %d, out: %u in: %u\n",
                    head, out, in);
        /* On error, stop handling until the next kick. */
        if (unlikely(head < 0))
            break;
        /* Nothing new?  Wait for eventfd to tell us they refilled. */
        if (head == vq->num) {
            if (unlikely(vhost_enable_notify(&vs->dev, vq))) {
                vhost_disable_notify(&vs->dev, vq);
                continue;
            }
            break;
        }

/* FIXME: BIDI operation */
        if (out == 1 && in == 1) {
            data_direction = DMA_NONE;
            data_first = 0;
            data_num = 0;
        } else if (out == 1 && in > 1) {
            data_direction = DMA_FROM_DEVICE;
            data_first = out + 1;
            data_num = in - 1;
        } else if (out > 1 && in == 1) {
            data_direction = DMA_TO_DEVICE;
            data_first = 1;
            data_num = out - 1;
        } else {
            vq_err(vq, "Invalid buffer layout out: %u in: %u\n",
                    out, in);
            break;
        }

        /*
         * Check for a sane resp buffer so we can report errors to
         * the guest.
         */
        if (unlikely(vq->iov[out].iov_len !=
                    sizeof(struct virtio_scsi_cmd_resp))) {
            vq_err(vq, "Expecting virtio_scsi_cmd_resp, got %zu"
                " bytes\n", vq->iov[out].iov_len);
            break;
        }

        if (unlikely(vq->iov[0].iov_len != sizeof(v_req))) {
            vq_err(vq, "Expecting virtio_scsi_cmd_req, got %zu"
                " bytes\n", vq->iov[0].iov_len);
            break;
        }
        pr_debug("Calling __copy_from_user: vq->iov[0].iov_base: %p,"
            " len: %zu\n", vq->iov[0].iov_base, sizeof(v_req));
        ret = __copy_from_user(&v_req, vq->iov[0].iov_base,
                sizeof(v_req));
        if (unlikely(ret)) {
            vq_err(vq, "Faulted on virtio_scsi_cmd_req\n");
            break;
        }

        exp_data_len = 0;
        for (i = 0; i < data_num; i++)
            exp_data_len += vq->iov[data_first + i].iov_len;

        tv_cmd = vhost_scsi_allocate_cmd(tv_tpg, &v_req,
                    exp_data_len, data_direction);
        if (IS_ERR(tv_cmd)) {
            vq_err(vq, "vhost_scsi_allocate_cmd failed %ld\n",
                    PTR_ERR(tv_cmd));
            break;
        }
        pr_debug("Allocated tv_cmd: %p exp_data_len: %d, data_direction"
            ": %d\n", tv_cmd, exp_data_len, data_direction);

        tv_cmd->tvc_vhost = vs;

        if (unlikely(vq->iov[out].iov_len !=
                sizeof(struct virtio_scsi_cmd_resp))) {
            vq_err(vq, "Expecting virtio_scsi_cmd_resp, got %zu"
                " bytes, out: %d, in: %d\n",
                vq->iov[out].iov_len, out, in);
            break;
        }

        tv_cmd->tvc_resp = vq->iov[out].iov_base;

        /*
         * Copy in the recieved CDB descriptor into tv_cmd->tvc_cdb
         * that will be used by tcm_vhost_new_cmd_map() and down into
         * target_setup_cmd_from_cdb()
         */
        memcpy(tv_cmd->tvc_cdb, v_req.cdb, TCM_VHOST_MAX_CDB_SIZE);
        /*
         * Check that the recieved CDB size does not exceeded our
         * hardcoded max for tcm_vhost
         */
        /* TODO what if cdb was too small for varlen cdb header? */
        if (unlikely(scsi_command_size(tv_cmd->tvc_cdb) >
                    TCM_VHOST_MAX_CDB_SIZE)) {
            vq_err(vq, "Received SCSI CDB with command_size: %d that"
                " exceeds SCSI_MAX_VARLEN_CDB_SIZE: %d\n",
                scsi_command_size(tv_cmd->tvc_cdb),
                TCM_VHOST_MAX_CDB_SIZE);
            break; /* TODO */
        }
        tv_cmd->tvc_lun = ((v_req.lun[2] << 8) | v_req.lun[3]) & 0x3FFF;

        pr_debug("vhost_scsi got command opcode: %#02x, lun: %d\n",
            tv_cmd->tvc_cdb[0], tv_cmd->tvc_lun);

        if (data_direction != DMA_NONE) {
            ret = vhost_scsi_map_iov_to_sgl(tv_cmd,
                    &vq->iov[data_first], data_num,
                    data_direction == DMA_TO_DEVICE);
            if (unlikely(ret)) {
                vq_err(vq, "Failed to map iov to sgl\n");
                break; /* TODO */
            }
        }

        /*
         * Save the descriptor from vhost_get_vq_desc() to be used to
         * complete the virtio-scsi request in TCM callback context via
         * tcm_vhost_queue_data_in() and tcm_vhost_queue_status()
         */
        tv_cmd->tvc_vq_desc = head;
        /*
         * Dispatch tv_cmd descriptor for cmwq execution in process
         * context provided by tcm_vhost_workqueue.  This also ensures
         * tv_cmd is executed on the same kworker CPU as this vhost
         * thread to gain positive L2 cache locality effects..
         */
        INIT_WORK(&tv_cmd->work, tcm_vhost_submission_work);
        queue_work(tcm_vhost_workqueue, &tv_cmd->work);
    }

    mutex_unlock(&vq->mutex);
}

static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
{
    pr_debug("%s: The handling func for control queue.\n", __func__);
}

static void vhost_scsi_evt_handle_kick(struct vhost_work *work)
{
    pr_debug("%s: The handling func for event queue.\n", __func__);
}

static void vhost_scsi_handle_kick(struct vhost_work *work)
{
    struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
                        poll.work);
    struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev);

    vhost_scsi_handle_vq(vs);
}

/*
 * Called from vhost_scsi_ioctl() context to walk the list of available
 * tcm_vhost_tpg with an active struct tcm_vhost_nexus
 */
static int vhost_scsi_set_endpoint(
    struct vhost_scsi *vs,
    struct vhost_scsi_target *t)
{
    struct tcm_vhost_tport *tv_tport;
    struct tcm_vhost_tpg *tv_tpg;
    int index;

    mutex_lock(&vs->dev.mutex);
    /* Verify that ring has been setup correctly. */
    for (index = 0; index < vs->dev.nvqs; ++index) {
        /* Verify that ring has been setup correctly. */
        if (!vhost_vq_access_ok(&vs->vqs[index])) {
            mutex_unlock(&vs->dev.mutex);
            return -EFAULT;
        }
    }
    mutex_unlock(&vs->dev.mutex);

    mutex_lock(&tcm_vhost_mutex);
    list_for_each_entry(tv_tpg, &tcm_vhost_list, tv_tpg_list) {
        mutex_lock(&tv_tpg->tv_tpg_mutex);
        if (!tv_tpg->tpg_nexus) {
            mutex_unlock(&tv_tpg->tv_tpg_mutex);
            continue;
        }
        if (tv_tpg->tv_tpg_vhost_count != 0) {
            mutex_unlock(&tv_tpg->tv_tpg_mutex);
            continue;
        }
        tv_tport = tv_tpg->tport;

        if (!strcmp(tv_tport->tport_name, t->vhost_wwpn) &&
            (tv_tpg->tport_tpgt == t->vhost_tpgt)) {
            tv_tpg->tv_tpg_vhost_count++;
            mutex_unlock(&tv_tpg->tv_tpg_mutex);
            mutex_unlock(&tcm_vhost_mutex);

            mutex_lock(&vs->dev.mutex);
            if (vs->vs_tpg) {
                mutex_unlock(&vs->dev.mutex);
                mutex_lock(&tv_tpg->tv_tpg_mutex);
                tv_tpg->tv_tpg_vhost_count--;
                mutex_unlock(&tv_tpg->tv_tpg_mutex);
                return -EEXIST;
            }

            vs->vs_tpg = tv_tpg;
            smp_mb__after_atomic_inc();
            mutex_unlock(&vs->dev.mutex);
            return 0;
        }
        mutex_unlock(&tv_tpg->tv_tpg_mutex);
    }
    mutex_unlock(&tcm_vhost_mutex);
    return -EINVAL;
}

static int vhost_scsi_clear_endpoint(
    struct vhost_scsi *vs,
    struct vhost_scsi_target *t)
{
    struct tcm_vhost_tport *tv_tport;
    struct tcm_vhost_tpg *tv_tpg;
    int index, ret;

    mutex_lock(&vs->dev.mutex);
    /* Verify that ring has been setup correctly. */
    for (index = 0; index < vs->dev.nvqs; ++index) {
        if (!vhost_vq_access_ok(&vs->vqs[index])) {
            ret = -EFAULT;
            goto err;
        }
    }

    if (!vs->vs_tpg) {
        ret = -ENODEV;
        goto err;
    }
    tv_tpg = vs->vs_tpg;
    tv_tport = tv_tpg->tport;

    if (strcmp(tv_tport->tport_name, t->vhost_wwpn) ||
        (tv_tpg->tport_tpgt != t->vhost_tpgt)) {
        pr_warn("tv_tport->tport_name: %s, tv_tpg->tport_tpgt: %hu"
            " does not match t->vhost_wwpn: %s, t->vhost_tpgt: %hu\n",
            tv_tport->tport_name, tv_tpg->tport_tpgt,
            t->vhost_wwpn, t->vhost_tpgt);
        ret = -EINVAL;
        goto err;
    }
    tv_tpg->tv_tpg_vhost_count--;
    vs->vs_tpg = NULL;
    mutex_unlock(&vs->dev.mutex);

    return 0;

err:
    mutex_unlock(&vs->dev.mutex);
    return ret;
}

static int vhost_scsi_open(struct inode *inode, struct file *f)
{
    struct vhost_scsi *s;
    int r;

    s = kzalloc(sizeof(*s), GFP_KERNEL);
    if (!s)
        return -ENOMEM;

    vhost_work_init(&s->vs_completion_work, vhost_scsi_complete_cmd_work);
    INIT_LIST_HEAD(&s->vs_completion_list);
    spin_lock_init(&s->vs_completion_lock);

    s->vqs[VHOST_SCSI_VQ_CTL].handle_kick = vhost_scsi_ctl_handle_kick;
    s->vqs[VHOST_SCSI_VQ_EVT].handle_kick = vhost_scsi_evt_handle_kick;
    s->vqs[VHOST_SCSI_VQ_IO].handle_kick = vhost_scsi_handle_kick;
    r = vhost_dev_init(&s->dev, s->vqs, 3);
    if (r < 0) {
        kfree(s);
        return r;
    }

    f->private_data = s;
    return 0;
}

static int vhost_scsi_release(struct inode *inode, struct file *f)
{
    struct vhost_scsi *s = f->private_data;

    if (s->vs_tpg && s->vs_tpg->tport) {
        struct vhost_scsi_target backend;

        memcpy(backend.vhost_wwpn, s->vs_tpg->tport->tport_name,
                sizeof(backend.vhost_wwpn));
        backend.vhost_tpgt = s->vs_tpg->tport_tpgt;
        vhost_scsi_clear_endpoint(s, &backend);
    }

    vhost_dev_cleanup(&s->dev, false);
    kfree(s);
    return 0;
}

static void vhost_scsi_flush_vq(struct vhost_scsi *vs, int index)
{
    vhost_poll_flush(&vs->dev.vqs[index].poll);
}

static void vhost_scsi_flush(struct vhost_scsi *vs)
{
    vhost_scsi_flush_vq(vs, VHOST_SCSI_VQ_CTL);
    vhost_scsi_flush_vq(vs, VHOST_SCSI_VQ_EVT);
    vhost_scsi_flush_vq(vs, VHOST_SCSI_VQ_IO);
}

static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
{
    if (features & ~VHOST_FEATURES)
        return -EOPNOTSUPP;

    mutex_lock(&vs->dev.mutex);
    if ((features & (1 << VHOST_F_LOG_ALL)) &&
        !vhost_log_access_ok(&vs->dev)) {
        mutex_unlock(&vs->dev.mutex);
        return -EFAULT;
    }
    vs->dev.acked_features = features;
    smp_wmb();
    vhost_scsi_flush(vs);
    mutex_unlock(&vs->dev.mutex);
    return 0;
}

static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
                unsigned long arg)
{
    struct vhost_scsi *vs = f->private_data;
    struct vhost_scsi_target backend;
    void __user *argp = (void __user *)arg;
    u64 __user *featurep = argp;
    u64 features;
    int r, abi_version = VHOST_SCSI_ABI_VERSION;

    switch (ioctl) {
    case VHOST_SCSI_SET_ENDPOINT:
        if (copy_from_user(&backend, argp, sizeof backend))
            return -EFAULT;
        if (backend.reserved != 0)
            return -EOPNOTSUPP;

        return vhost_scsi_set_endpoint(vs, &backend);
    case VHOST_SCSI_CLEAR_ENDPOINT:
        if (copy_from_user(&backend, argp, sizeof backend))
            return -EFAULT;
        if (backend.reserved != 0)
            return -EOPNOTSUPP;

        return vhost_scsi_clear_endpoint(vs, &backend);
    case VHOST_SCSI_GET_ABI_VERSION:
        if (copy_to_user(argp, &abi_version, sizeof abi_version))
            return -EFAULT;
        return 0;
    case VHOST_GET_FEATURES:
        features = VHOST_FEATURES;
        if (copy_to_user(featurep, &features, sizeof features))
            return -EFAULT;
        return 0;
    case VHOST_SET_FEATURES:
        if (copy_from_user(&features, featurep, sizeof features))
            return -EFAULT;
        return vhost_scsi_set_features(vs, features);
    default:
        mutex_lock(&vs->dev.mutex);
        r = vhost_dev_ioctl(&vs->dev, ioctl, arg);
        mutex_unlock(&vs->dev.mutex);
        return r;
    }
}

#ifdef CONFIG_COMPAT
static long vhost_scsi_compat_ioctl(struct file *f, unsigned int ioctl,
                unsigned long arg)
{
    return vhost_scsi_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
}
#endif

static const struct file_operations vhost_scsi_fops = {
    .owner          = THIS_MODULE,
    .release        = vhost_scsi_release,
    .unlocked_ioctl = vhost_scsi_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl   = vhost_scsi_compat_ioctl,
#endif
    .open           = vhost_scsi_open,
    .llseek     = noop_llseek,
};

static struct miscdevice vhost_scsi_misc = {
    MISC_DYNAMIC_MINOR,
    "vhost-scsi",
    &vhost_scsi_fops,
};

static int __init vhost_scsi_register(void)
{
    return misc_register(&vhost_scsi_misc);
}

static int vhost_scsi_deregister(void)
{
    return misc_deregister(&vhost_scsi_misc);
}

static char *tcm_vhost_dump_proto_id(struct tcm_vhost_tport *tport)
{
    switch (tport->tport_proto_id) {
    case SCSI_PROTOCOL_SAS:
        return "SAS";
    case SCSI_PROTOCOL_FCP:
        return "FCP";
    case SCSI_PROTOCOL_ISCSI:
        return "iSCSI";
    default:
        break;
    }

    return "Unknown";
}

static int tcm_vhost_port_link(struct se_portal_group *se_tpg,
    struct se_lun *lun)
{
    struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
                struct tcm_vhost_tpg, se_tpg);

    mutex_lock(&tv_tpg->tv_tpg_mutex);
    tv_tpg->tv_tpg_port_count++;
    mutex_unlock(&tv_tpg->tv_tpg_mutex);

    return 0;
}

static void tcm_vhost_port_unlink(struct se_portal_group *se_tpg,
    struct se_lun *se_lun)
{
    struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
                struct tcm_vhost_tpg, se_tpg);

    mutex_lock(&tv_tpg->tv_tpg_mutex);
    tv_tpg->tv_tpg_port_count--;
    mutex_unlock(&tv_tpg->tv_tpg_mutex);
}

static struct se_node_acl *tcm_vhost_make_nodeacl(
    struct se_portal_group *se_tpg,
    struct config_group *group,
    const char *name)
{
    struct se_node_acl *se_nacl, *se_nacl_new;
    struct tcm_vhost_nacl *nacl;
    u64 wwpn = 0;
    u32 nexus_depth;

    /* tcm_vhost_parse_wwn(name, &wwpn, 1) < 0)
        return ERR_PTR(-EINVAL); */
    se_nacl_new = tcm_vhost_alloc_fabric_acl(se_tpg);
    if (!se_nacl_new)
        return ERR_PTR(-ENOMEM);

    nexus_depth = 1;
    /*
     * se_nacl_new may be released by core_tpg_add_initiator_node_acl()
     * when converting a NodeACL from demo mode -> explict
     */
    se_nacl = core_tpg_add_initiator_node_acl(se_tpg, se_nacl_new,
                name, nexus_depth);
    if (IS_ERR(se_nacl)) {
        tcm_vhost_release_fabric_acl(se_tpg, se_nacl_new);
        return se_nacl;
    }
    /*
     * Locate our struct tcm_vhost_nacl and set the FC Nport WWPN
     */
    nacl = container_of(se_nacl, struct tcm_vhost_nacl, se_node_acl);
    nacl->iport_wwpn = wwpn;

    return se_nacl;
}

static void tcm_vhost_drop_nodeacl(struct se_node_acl *se_acl)
{
    struct tcm_vhost_nacl *nacl = container_of(se_acl,
                struct tcm_vhost_nacl, se_node_acl);
    core_tpg_del_initiator_node_acl(se_acl->se_tpg, se_acl, 1);
    kfree(nacl);
}

static int tcm_vhost_make_nexus(struct tcm_vhost_tpg *tv_tpg,
    const char *name)
{
    struct se_portal_group *se_tpg;
    struct tcm_vhost_nexus *tv_nexus;

    mutex_lock(&tv_tpg->tv_tpg_mutex);
    if (tv_tpg->tpg_nexus) {
        mutex_unlock(&tv_tpg->tv_tpg_mutex);
        pr_debug("tv_tpg->tpg_nexus already exists\n");
        return -EEXIST;
    }
    se_tpg = &tv_tpg->se_tpg;

    tv_nexus = kzalloc(sizeof(struct tcm_vhost_nexus), GFP_KERNEL);
    if (!tv_nexus) {
        mutex_unlock(&tv_tpg->tv_tpg_mutex);
        pr_err("Unable to allocate struct tcm_vhost_nexus\n");
        return -ENOMEM;
    }
    /*
     *  Initialize the struct se_session pointer
     */
    tv_nexus->tvn_se_sess = transport_init_session();
    if (IS_ERR(tv_nexus->tvn_se_sess)) {
        mutex_unlock(&tv_tpg->tv_tpg_mutex);
        kfree(tv_nexus);
        return -ENOMEM;
    }
    /*
     * Since we are running in 'demo mode' this call with generate a
     * struct se_node_acl for the tcm_vhost struct se_portal_group with
     * the SCSI Initiator port name of the passed configfs group 'name'.
     */
    tv_nexus->tvn_se_sess->se_node_acl = core_tpg_check_initiator_node_acl(
                se_tpg, (unsigned char *)name);
    if (!tv_nexus->tvn_se_sess->se_node_acl) {
        mutex_unlock(&tv_tpg->tv_tpg_mutex);
        pr_debug("core_tpg_check_initiator_node_acl() failed"
                " for %s\n", name);
        transport_free_session(tv_nexus->tvn_se_sess);
        kfree(tv_nexus);
        return -ENOMEM;
    }
    /*
     * Now register the TCM vhost virtual I_T Nexus as active with the
     * call to __transport_register_session()
     */
    __transport_register_session(se_tpg, tv_nexus->tvn_se_sess->se_node_acl,
            tv_nexus->tvn_se_sess, tv_nexus);
    tv_tpg->tpg_nexus = tv_nexus;

    mutex_unlock(&tv_tpg->tv_tpg_mutex);
    return 0;
}

static int tcm_vhost_drop_nexus(struct tcm_vhost_tpg *tpg)
{
    struct se_session *se_sess;
    struct tcm_vhost_nexus *tv_nexus;

    mutex_lock(&tpg->tv_tpg_mutex);
    tv_nexus = tpg->tpg_nexus;
    if (!tv_nexus) {
        mutex_unlock(&tpg->tv_tpg_mutex);
        return -ENODEV;
    }

    se_sess = tv_nexus->tvn_se_sess;
    if (!se_sess) {
        mutex_unlock(&tpg->tv_tpg_mutex);
        return -ENODEV;
    }

    if (tpg->tv_tpg_port_count != 0) {
        mutex_unlock(&tpg->tv_tpg_mutex);
        pr_err("Unable to remove TCM_vhost I_T Nexus with"
            " active TPG port count: %d\n",
            tpg->tv_tpg_port_count);
        return -EBUSY;
    }

    if (tpg->tv_tpg_vhost_count != 0) {
        mutex_unlock(&tpg->tv_tpg_mutex);
        pr_err("Unable to remove TCM_vhost I_T Nexus with"
            " active TPG vhost count: %d\n",
            tpg->tv_tpg_vhost_count);
        return -EBUSY;
    }

    pr_debug("TCM_vhost_ConfigFS: Removing I_T Nexus to emulated"
        " %s Initiator Port: %s\n", tcm_vhost_dump_proto_id(tpg->tport),
        tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
    /*
     * Release the SCSI I_T Nexus to the emulated vhost Target Port
     */
    transport_deregister_session(tv_nexus->tvn_se_sess);
    tpg->tpg_nexus = NULL;
    mutex_unlock(&tpg->tv_tpg_mutex);

    kfree(tv_nexus);
    return 0;
}

static ssize_t tcm_vhost_tpg_show_nexus(struct se_portal_group *se_tpg,
    char *page)
{
    struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
                struct tcm_vhost_tpg, se_tpg);
    struct tcm_vhost_nexus *tv_nexus;
    ssize_t ret;

    mutex_lock(&tv_tpg->tv_tpg_mutex);
    tv_nexus = tv_tpg->tpg_nexus;
    if (!tv_nexus) {
        mutex_unlock(&tv_tpg->tv_tpg_mutex);
        return -ENODEV;
    }
    ret = snprintf(page, PAGE_SIZE, "%s\n",
            tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
    mutex_unlock(&tv_tpg->tv_tpg_mutex);

    return ret;
}

static ssize_t tcm_vhost_tpg_store_nexus(struct se_portal_group *se_tpg,
    const char *page,
    size_t count)
{
    struct tcm_vhost_tpg *tv_tpg = container_of(se_tpg,
                struct tcm_vhost_tpg, se_tpg);
    struct tcm_vhost_tport *tport_wwn = tv_tpg->tport;
    unsigned char i_port[TCM_VHOST_NAMELEN], *ptr, *port_ptr;
    int ret;
    /*
     * Shutdown the active I_T nexus if 'NULL' is passed..
     */
    if (!strncmp(page, "NULL", 4)) {
        ret = tcm_vhost_drop_nexus(tv_tpg);
        return (!ret) ? count : ret;
    }
    /*
     * Otherwise make sure the passed virtual Initiator port WWN matches
     * the fabric protocol_id set in tcm_vhost_make_tport(), and call
     * tcm_vhost_make_nexus().
     */
    if (strlen(page) >= TCM_VHOST_NAMELEN) {
        pr_err("Emulated NAA Sas Address: %s, exceeds"
                " max: %d\n", page, TCM_VHOST_NAMELEN);
        return -EINVAL;
    }
    snprintf(&i_port[0], TCM_VHOST_NAMELEN, "%s", page);

    ptr = strstr(i_port, "naa.");
    if (ptr) {
        if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_SAS) {
            pr_err("Passed SAS Initiator Port %s does not"
                " match target port protoid: %s\n", i_port,
                tcm_vhost_dump_proto_id(tport_wwn));
            return -EINVAL;
        }
        port_ptr = &i_port[0];
        goto check_newline;
    }
    ptr = strstr(i_port, "fc.");
    if (ptr) {
        if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_FCP) {
            pr_err("Passed FCP Initiator Port %s does not"
                " match target port protoid: %s\n", i_port,
                tcm_vhost_dump_proto_id(tport_wwn));
            return -EINVAL;
        }
        port_ptr = &i_port[3]; /* Skip over "fc." */
        goto check_newline;
    }
    ptr = strstr(i_port, "iqn.");
    if (ptr) {
        if (tport_wwn->tport_proto_id != SCSI_PROTOCOL_ISCSI) {
            pr_err("Passed iSCSI Initiator Port %s does not"
                " match target port protoid: %s\n", i_port,
                tcm_vhost_dump_proto_id(tport_wwn));
            return -EINVAL;
        }
        port_ptr = &i_port[0];
        goto check_newline;
    }
    pr_err("Unable to locate prefix for emulated Initiator Port:"
            " %s\n", i_port);
    return -EINVAL;
    /*
     * Clear any trailing newline for the NAA WWN
     */
check_newline:
    if (i_port[strlen(i_port)-1] == '\n')
        i_port[strlen(i_port)-1] = '\0';

    ret = tcm_vhost_make_nexus(tv_tpg, port_ptr);
    if (ret < 0)
        return ret;

    return count;
}

TF_TPG_BASE_ATTR(tcm_vhost, nexus, S_IRUGO | S_IWUSR);

static struct configfs_attribute *tcm_vhost_tpg_attrs[] = {
    &tcm_vhost_tpg_nexus.attr,
    NULL,
};

static struct se_portal_group *tcm_vhost_make_tpg(struct se_wwn *wwn,
    struct config_group *group,
    const char *name)
{
    struct tcm_vhost_tport *tport = container_of(wwn,
            struct tcm_vhost_tport, tport_wwn);

    struct tcm_vhost_tpg *tpg;
    unsigned long tpgt;
    int ret;

    if (strstr(name, "tpgt_") != name)
        return ERR_PTR(-EINVAL);
    if (kstrtoul(name + 5, 10, &tpgt) || tpgt > UINT_MAX)
        return ERR_PTR(-EINVAL);

    tpg = kzalloc(sizeof(struct tcm_vhost_tpg), GFP_KERNEL);
    if (!tpg) {
        pr_err("Unable to allocate struct tcm_vhost_tpg");
        return ERR_PTR(-ENOMEM);
    }
    mutex_init(&tpg->tv_tpg_mutex);
    INIT_LIST_HEAD(&tpg->tv_tpg_list);
    tpg->tport = tport;
    tpg->tport_tpgt = tpgt;

    ret = core_tpg_register(&tcm_vhost_fabric_configfs->tf_ops, wwn,
                &tpg->se_tpg, tpg, TRANSPORT_TPG_TYPE_NORMAL);
    if (ret < 0) {
        kfree(tpg);
        return NULL;
    }
    mutex_lock(&tcm_vhost_mutex);
    list_add_tail(&tpg->tv_tpg_list, &tcm_vhost_list);
    mutex_unlock(&tcm_vhost_mutex);

    return &tpg->se_tpg;
}

static void tcm_vhost_drop_tpg(struct se_portal_group *se_tpg)
{
    struct tcm_vhost_tpg *tpg = container_of(se_tpg,
                struct tcm_vhost_tpg, se_tpg);

    mutex_lock(&tcm_vhost_mutex);
    list_del(&tpg->tv_tpg_list);
    mutex_unlock(&tcm_vhost_mutex);
    /*
     * Release the virtual I_T Nexus for this vhost TPG
     */
    tcm_vhost_drop_nexus(tpg);
    /*
     * Deregister the se_tpg from TCM..
     */
    core_tpg_deregister(se_tpg);
    kfree(tpg);
}

static struct se_wwn *tcm_vhost_make_tport(struct target_fabric_configfs *tf,
    struct config_group *group,
    const char *name)
{
    struct tcm_vhost_tport *tport;
    char *ptr;
    u64 wwpn = 0;
    int off = 0;

    /* if (tcm_vhost_parse_wwn(name, &wwpn, 1) < 0)
        return ERR_PTR(-EINVAL); */

    tport = kzalloc(sizeof(struct tcm_vhost_tport), GFP_KERNEL);
    if (!tport) {
        pr_err("Unable to allocate struct tcm_vhost_tport");
        return ERR_PTR(-ENOMEM);
    }
    tport->tport_wwpn = wwpn;
    /*
     * Determine the emulated Protocol Identifier and Target Port Name
     * based on the incoming configfs directory name.
     */
    ptr = strstr(name, "naa.");
    if (ptr) {
        tport->tport_proto_id = SCSI_PROTOCOL_SAS;
        goto check_len;
    }
    ptr = strstr(name, "fc.");
    if (ptr) {
        tport->tport_proto_id = SCSI_PROTOCOL_FCP;
        off = 3; /* Skip over "fc." */
        goto check_len;
    }
    ptr = strstr(name, "iqn.");
    if (ptr) {
        tport->tport_proto_id = SCSI_PROTOCOL_ISCSI;
        goto check_len;
    }

    pr_err("Unable to locate prefix for emulated Target Port:"
            " %s\n", name);
    kfree(tport);
    return ERR_PTR(-EINVAL);

check_len:
    if (strlen(name) >= TCM_VHOST_NAMELEN) {
        pr_err("Emulated %s Address: %s, exceeds"
            " max: %d\n", name, tcm_vhost_dump_proto_id(tport),
            TCM_VHOST_NAMELEN);
        kfree(tport);
        return ERR_PTR(-EINVAL);
    }
    snprintf(&tport->tport_name[0], TCM_VHOST_NAMELEN, "%s", &name[off]);

    pr_debug("TCM_VHost_ConfigFS: Allocated emulated Target"
        " %s Address: %s\n", tcm_vhost_dump_proto_id(tport), name);

    return &tport->tport_wwn;
}

static void tcm_vhost_drop_tport(struct se_wwn *wwn)
{
    struct tcm_vhost_tport *tport = container_of(wwn,
                struct tcm_vhost_tport, tport_wwn);

    pr_debug("TCM_VHost_ConfigFS: Deallocating emulated Target"
        " %s Address: %s\n", tcm_vhost_dump_proto_id(tport),
        tport->tport_name);

    kfree(tport);
}

static ssize_t tcm_vhost_wwn_show_attr_version(
    struct target_fabric_configfs *tf,
    char *page)
{
    return sprintf(page, "TCM_VHOST fabric module %s on %s/%s"
        "on "UTS_RELEASE"\n", TCM_VHOST_VERSION, utsname()->sysname,
        utsname()->machine);
}

TF_WWN_ATTR_RO(tcm_vhost, version);

static struct configfs_attribute *tcm_vhost_wwn_attrs[] = {
    &tcm_vhost_wwn_version.attr,
    NULL,
};

static struct target_core_fabric_ops tcm_vhost_ops = {
    .get_fabric_name        = tcm_vhost_get_fabric_name,
    .get_fabric_proto_ident     = tcm_vhost_get_fabric_proto_ident,
    .tpg_get_wwn            = tcm_vhost_get_fabric_wwn,
    .tpg_get_tag            = tcm_vhost_get_tag,
    .tpg_get_default_depth      = tcm_vhost_get_default_depth,
    .tpg_get_pr_transport_id    = tcm_vhost_get_pr_transport_id,
    .tpg_get_pr_transport_id_len    = tcm_vhost_get_pr_transport_id_len,
    .tpg_parse_pr_out_transport_id  = tcm_vhost_parse_pr_out_transport_id,
    .tpg_check_demo_mode        = tcm_vhost_check_true,
    .tpg_check_demo_mode_cache  = tcm_vhost_check_true,
    .tpg_check_demo_mode_write_protect = tcm_vhost_check_false,
    .tpg_check_prod_mode_write_protect = tcm_vhost_check_false,
    .tpg_alloc_fabric_acl       = tcm_vhost_alloc_fabric_acl,
    .tpg_release_fabric_acl     = tcm_vhost_release_fabric_acl,
    .tpg_get_inst_index     = tcm_vhost_tpg_get_inst_index,
    .release_cmd            = tcm_vhost_release_cmd,
    .shutdown_session       = tcm_vhost_shutdown_session,
    .close_session          = tcm_vhost_close_session,
    .sess_get_index         = tcm_vhost_sess_get_index,
    .sess_get_initiator_sid     = NULL,
    .write_pending          = tcm_vhost_write_pending,
    .write_pending_status       = tcm_vhost_write_pending_status,
    .set_default_node_attributes    = tcm_vhost_set_default_node_attrs,
    .get_task_tag           = tcm_vhost_get_task_tag,
    .get_cmd_state          = tcm_vhost_get_cmd_state,
    .queue_data_in          = tcm_vhost_queue_data_in,
    .queue_status           = tcm_vhost_queue_status,
    .queue_tm_rsp           = tcm_vhost_queue_tm_rsp,
    /*
     * Setup callers for generic logic in target_core_fabric_configfs.c
     */
    .fabric_make_wwn        = tcm_vhost_make_tport,
    .fabric_drop_wwn        = tcm_vhost_drop_tport,
    .fabric_make_tpg        = tcm_vhost_make_tpg,
    .fabric_drop_tpg        = tcm_vhost_drop_tpg,
    .fabric_post_link       = tcm_vhost_port_link,
    .fabric_pre_unlink      = tcm_vhost_port_unlink,
    .fabric_make_np         = NULL,
    .fabric_drop_np         = NULL,
    .fabric_make_nodeacl        = tcm_vhost_make_nodeacl,
    .fabric_drop_nodeacl        = tcm_vhost_drop_nodeacl,
};

static int tcm_vhost_register_configfs(void)
{
    struct target_fabric_configfs *fabric;
    int ret;

    pr_debug("TCM_VHOST fabric module %s on %s/%s"
        " on "UTS_RELEASE"\n", TCM_VHOST_VERSION, utsname()->sysname,
        utsname()->machine);
    /*
     * Register the top level struct config_item_type with TCM core
     */
    fabric = target_fabric_configfs_init(THIS_MODULE, "vhost");
    if (IS_ERR(fabric)) {
        pr_err("target_fabric_configfs_init() failed\n");
        return PTR_ERR(fabric);
    }
    /*
     * Setup fabric->tf_ops from our local tcm_vhost_ops
     */
    fabric->tf_ops = tcm_vhost_ops;
    /*
     * Setup default attribute lists for various fabric->tf_cit_tmpl
     */
    TF_CIT_TMPL(fabric)->tfc_wwn_cit.ct_attrs = tcm_vhost_wwn_attrs;
    TF_CIT_TMPL(fabric)->tfc_tpg_base_cit.ct_attrs = tcm_vhost_tpg_attrs;
    TF_CIT_TMPL(fabric)->tfc_tpg_attrib_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_param_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_np_base_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_nacl_base_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_nacl_attrib_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_nacl_auth_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_nacl_param_cit.ct_attrs = NULL;
    /*
     * Register the fabric for use within TCM
     */
    ret = target_fabric_configfs_register(fabric);
    if (ret < 0) {
        pr_err("target_fabric_configfs_register() failed"
                " for TCM_VHOST\n");
        return ret;
    }
    /*
     * Setup our local pointer to *fabric
     */
    tcm_vhost_fabric_configfs = fabric;
    pr_debug("TCM_VHOST[0] - Set fabric -> tcm_vhost_fabric_configfs\n");
    return 0;
};

static void tcm_vhost_deregister_configfs(void)
{
    if (!tcm_vhost_fabric_configfs)
        return;

    target_fabric_configfs_deregister(tcm_vhost_fabric_configfs);
    tcm_vhost_fabric_configfs = NULL;
    pr_debug("TCM_VHOST[0] - Cleared tcm_vhost_fabric_configfs\n");
};

static int __init tcm_vhost_init(void)
{
    int ret = -ENOMEM;
    /*
     * Use our own dedicated workqueue for submitting I/O into
     * target core to avoid contention within system_wq.
     */
    tcm_vhost_workqueue = alloc_workqueue("tcm_vhost", 0, 0);
    if (!tcm_vhost_workqueue)
        goto out;

    ret = vhost_scsi_register();
    if (ret < 0)
        goto out_destroy_workqueue;

    ret = tcm_vhost_register_configfs();
    if (ret < 0)
        goto out_vhost_scsi_deregister;

    return 0;

out_vhost_scsi_deregister:
    vhost_scsi_deregister();
out_destroy_workqueue:
    destroy_workqueue(tcm_vhost_workqueue);
out:
    return ret;
};

static void tcm_vhost_exit(void)
{
    tcm_vhost_deregister_configfs();
    vhost_scsi_deregister();
    destroy_workqueue(tcm_vhost_workqueue);
};

MODULE_DESCRIPTION("TCM_VHOST series fabric driver");
MODULE_LICENSE("GPL");
module_init(tcm_vhost_init);
module_exit(tcm_vhost_exit);