Merge git://git.infradead.org/users/willy/linux-nvme

[linux-2.6/cjktty.git] / drivers / vhost / tcm_vhost.c

/*******************************************************************************
 * 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 <nab@risingtidesystems.com>
 *          Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
 *
 * 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/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 <linux/llist.h>
#include <linux/bitmap.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,
};

#define VHOST_SCSI_MAX_TARGET   256
#define VHOST_SCSI_MAX_VQ       128

struct vhost_scsi {
        /* Protected by vhost_scsi->dev.mutex */
        struct tcm_vhost_tpg *vs_tpg[VHOST_SCSI_MAX_TARGET];
        char vs_vhost_wwpn[TRANSPORT_IQN_LEN];
        bool vs_endpoint;

        struct vhost_dev dev;
        struct vhost_virtqueue vqs[VHOST_SCSI_MAX_VQ];

        struct vhost_work vs_completion_work; /* cmd completion work item */
        struct llist_head vs_completion_list; /* cmd completion queue */
};

/* 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 iov_num_pages(struct iovec *iov)
{
        return (PAGE_ALIGN((unsigned long)iov->iov_base + iov->iov_len) -
               ((unsigned long)iov->iov_base & PAGE_MASK)) >> PAGE_SHIFT;
}

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 allocate 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;

        llist_add(&tv_cmd->tvc_completion_list, &vs->vs_completion_list);

        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);
}

/* 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);
        DECLARE_BITMAP(signal, VHOST_SCSI_MAX_VQ);
        struct virtio_scsi_cmd_resp v_rsp;
        struct tcm_vhost_cmd *tv_cmd;
        struct llist_node *llnode;
        struct se_cmd *se_cmd;
        int ret, vq;

        bitmap_zero(signal, VHOST_SCSI_MAX_VQ);
        llnode = llist_del_all(&vs->vs_completion_list);
        while (llnode) {
                tv_cmd = llist_entry(llnode, struct tcm_vhost_cmd,
                                     tvc_completion_list);
                llnode = llist_next(llnode);
                se_cmd = &tv_cmd->tvc_se_cmd;

                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(tv_cmd->tvc_vq, tv_cmd->tvc_vq_desc, 0);
                        vq = tv_cmd->tvc_vq - vs->vqs;
                        __set_bit(vq, signal);
                } else
                        pr_err("Faulted on virtio_scsi_cmd_resp\n");

                vhost_scsi_free_cmd(tv_cmd);
        }

        vq = -1;
        while ((vq = find_next_bit(signal, VHOST_SCSI_MAX_VQ, vq + 1))
                < VHOST_SCSI_MAX_VQ)
                vhost_signal(&vs->dev, &vs->vqs[vq]);
}

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;

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

        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);
        }
        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, struct iovec *iov, int write)
{
        unsigned int npages = 0, pages_nr, offset, nbytes;
        struct scatterlist *sg = sgl;
        void __user *ptr = iov->iov_base;
        size_t len = iov->iov_len;
        struct page **pages;
        int ret, i;

        pages_nr = iov_num_pages(iov);
        if (pages_nr > sgl_count)
                return -ENOBUFS;

        pages = kmalloc(pages_nr * sizeof(struct page *), GFP_KERNEL);
        if (!pages)
                return -ENOMEM;

        ret = get_user_pages_fast((unsigned long)ptr, pages_nr, write, pages);
        /* No pages were pinned */
        if (ret < 0)
                goto out;
        /* Less pages pinned than wanted */
        if (ret != pages_nr) {
                for (i = 0; i < ret; i++)
                        put_page(pages[i]);
                ret = -EFAULT;
                goto out;
        }

        while (len > 0) {
                offset = (uintptr_t)ptr & ~PAGE_MASK;
                nbytes = min_t(unsigned int, PAGE_SIZE - offset, len);
                sg_set_page(sg, pages[npages], nbytes, offset);
                ptr += nbytes;
                len -= nbytes;
                sg++;
                npages++;
        }

out:
        kfree(pages);
        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 += iov_num_pages(&iov[i]);

        /* 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], 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;
/* 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)
{
        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;
        u8 target;

        /* Must use ioctl VHOST_SCSI_SET_ENDPOINT */
        if (unlikely(!vs->vs_endpoint))
                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;
                }

                /* Extract the tpgt */
                target = v_req.lun[1];
                tv_tpg = vs->vs_tpg[target];

                /* Target does not exist, fail the request */
                if (unlikely(!tv_tpg)) {
                        struct virtio_scsi_cmd_resp __user *resp;
                        struct virtio_scsi_cmd_resp rsp;

                        memset(&rsp, 0, sizeof(rsp));
                        rsp.response = VIRTIO_SCSI_S_BAD_TARGET;
                        resp = vq->iov[out].iov_base;
                        ret = __copy_to_user(resp, &rsp, sizeof(rsp));
                        if (!ret)
                                vhost_add_used_and_signal(&vs->dev,
                                                          vq, head, 0);
                        else
                                pr_err("Faulted on virtio_scsi_cmd_resp\n");

                        continue;
                }

                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;
                tv_cmd->tvc_vq = vq;

                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, vq);
}

/*
 * 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;
        bool match = false;
        int index, ret;

        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_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)) {
                        if (vs->vs_tpg[tv_tpg->tport_tpgt]) {
                                mutex_unlock(&tv_tpg->tv_tpg_mutex);
                                mutex_unlock(&tcm_vhost_mutex);
                                mutex_unlock(&vs->dev.mutex);
                                return -EEXIST;
                        }
                        tv_tpg->tv_tpg_vhost_count++;
                        vs->vs_tpg[tv_tpg->tport_tpgt] = tv_tpg;
                        smp_mb__after_atomic_inc();
                        match = true;
                }
                mutex_unlock(&tv_tpg->tv_tpg_mutex);
        }
        mutex_unlock(&tcm_vhost_mutex);

        if (match) {
                memcpy(vs->vs_vhost_wwpn, t->vhost_wwpn,
                       sizeof(vs->vs_vhost_wwpn));
                vs->vs_endpoint = true;
                ret = 0;
        } else {
                ret = -EEXIST;
        }

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

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, i;
        u8 target;

        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;
                }
        }
        for (i = 0; i < VHOST_SCSI_MAX_TARGET; i++) {
                target = i;

                tv_tpg = vs->vs_tpg[target];
                if (!tv_tpg)
                        continue;

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

                if (strcmp(tv_tport->tport_name, t->vhost_wwpn)) {
                        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[target] = NULL;
                vs->vs_endpoint = false;
        }
        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, i;

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

        vhost_work_init(&s->vs_completion_work, vhost_scsi_complete_cmd_work);

        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;
        for (i = VHOST_SCSI_VQ_IO; i < VHOST_SCSI_MAX_VQ; i++)
                s->vqs[i].handle_kick = vhost_scsi_handle_kick;
        r = vhost_dev_init(&s->dev, s->vqs, VHOST_SCSI_MAX_VQ);
        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;
        struct vhost_scsi_target t;

        mutex_lock(&s->dev.mutex);
        memcpy(t.vhost_wwpn, s->vs_vhost_wwpn, sizeof(t.vhost_wwpn));
        mutex_unlock(&s->dev.mutex);
        vhost_scsi_clear_endpoint(s, &t);
        vhost_dev_stop(&s->dev);
        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)
{
        int i;

        for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
                vhost_scsi_flush_vq(vs, i);
}

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, argp);
                /* TODO: flush backend after dev ioctl. */
                if (r == -ENOIOCTLCMD)
                        r = vhost_vring_ioctl(&vs->dev, ioctl, argp);
                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);