/*******************************************************************************
   * Vhost kernel TCM fabric driver for virtio SCSI initiators
   *

   * (C) Copyright 2010-2013 Datera, Inc.

   * (C) Copyright 2010-2012 IBM Corp.
   *
   * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
   *

   * Authors: Nicholas A. Bellinger <nab@daterainc.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_scsi.h>

  #include <linux/llist.h>

  #include <linux/bitmap.h>

  #include <linux/percpu_ida.h>

  #include "vhost.h"

  
  #define TCM_VHOST_VERSION  "v0.1"
  #define TCM_VHOST_NAMELEN 256
  #define TCM_VHOST_MAX_CDB_SIZE 32

  #define TCM_VHOST_DEFAULT_TAGS 256

  #define TCM_VHOST_PREALLOC_SGLS 2048

  #define TCM_VHOST_PREALLOC_UPAGES 2048

  #define TCM_VHOST_PREALLOC_PROT_SGLS 512

  
  struct vhost_scsi_inflight {
  	/* Wait for the flush operation to finish */
  	struct completion comp;
  	/* Refcount for the inflight reqs */
  	struct kref kref;
  };
  
  struct tcm_vhost_cmd {
  	/* Descriptor from vhost_get_vq_desc() for virt_queue segment */
  	int tvc_vq_desc;
  	/* virtio-scsi initiator task attribute */
  	int tvc_task_attr;
  	/* virtio-scsi initiator data direction */
  	enum dma_data_direction tvc_data_direction;
  	/* Expected data transfer length from virtio-scsi header */
  	u32 tvc_exp_data_len;
  	/* The Tag from include/linux/virtio_scsi.h:struct virtio_scsi_cmd_req */
  	u64 tvc_tag;
  	/* The number of scatterlists associated with this cmd */
  	u32 tvc_sgl_count;

  	u32 tvc_prot_sgl_count;

  	/* Saved unpacked SCSI LUN for tcm_vhost_submission_work() */
  	u32 tvc_lun;
  	/* Pointer to the SGL formatted memory from virtio-scsi */
  	struct scatterlist *tvc_sgl;

  	struct scatterlist *tvc_prot_sgl;

  	struct page **tvc_upages;

  	/* Pointer to response */
  	struct virtio_scsi_cmd_resp __user *tvc_resp;
  	/* Pointer to vhost_scsi for our device */
  	struct vhost_scsi *tvc_vhost;
  	/* Pointer to vhost_virtqueue for the cmd */
  	struct vhost_virtqueue *tvc_vq;
  	/* Pointer to vhost nexus memory */
  	struct tcm_vhost_nexus *tvc_nexus;
  	/* The TCM I/O descriptor that is accessed via container_of() */
  	struct se_cmd tvc_se_cmd;
  	/* work item used for cmwq dispatch to tcm_vhost_submission_work() */
  	struct work_struct work;
  	/* Copy of the incoming SCSI command descriptor block (CDB) */
  	unsigned char tvc_cdb[TCM_VHOST_MAX_CDB_SIZE];
  	/* Sense buffer that will be mapped into outgoing status */
  	unsigned char tvc_sense_buf[TRANSPORT_SENSE_BUFFER];
  	/* Completed commands list, serviced from vhost worker thread */
  	struct llist_node tvc_completion_list;
  	/* Used to track inflight cmd */
  	struct vhost_scsi_inflight *inflight;
  };
  
  struct tcm_vhost_nexus {
  	/* Pointer to TCM session for I_T Nexus */
  	struct se_session *tvn_se_sess;
  };
  
  struct tcm_vhost_nacl {
  	/* Binary World Wide unique Port Name for Vhost Initiator port */
  	u64 iport_wwpn;
  	/* ASCII formatted WWPN for Sas Initiator port */
  	char iport_name[TCM_VHOST_NAMELEN];
  	/* Returned by tcm_vhost_make_nodeacl() */
  	struct se_node_acl se_node_acl;
  };

  struct tcm_vhost_tpg {
  	/* Vhost port target portal group tag for TCM */
  	u16 tport_tpgt;
  	/* Used to track number of TPG Port/Lun Links wrt to explict I_T Nexus shutdown */
  	int tv_tpg_port_count;
  	/* Used for vhost_scsi device reference to tpg_nexus, protected by tv_tpg_mutex */
  	int tv_tpg_vhost_count;
  	/* list for tcm_vhost_list */
  	struct list_head tv_tpg_list;
  	/* Used to protect access for tpg_nexus */
  	struct mutex tv_tpg_mutex;
  	/* Pointer to the TCM VHost I_T Nexus for this TPG endpoint */
  	struct tcm_vhost_nexus *tpg_nexus;
  	/* Pointer back to tcm_vhost_tport */
  	struct tcm_vhost_tport *tport;
  	/* Returned by tcm_vhost_make_tpg() */
  	struct se_portal_group se_tpg;
  	/* Pointer back to vhost_scsi, protected by tv_tpg_mutex */
  	struct vhost_scsi *vhost_scsi;
  };
  
  struct tcm_vhost_tport {
  	/* SCSI protocol the tport is providing */
  	u8 tport_proto_id;
  	/* Binary World Wide unique Port Name for Vhost Target port */
  	u64 tport_wwpn;
  	/* ASCII formatted WWPN for Vhost Target port */
  	char tport_name[TCM_VHOST_NAMELEN];
  	/* Returned by tcm_vhost_make_tport() */
  	struct se_wwn tport_wwn;
  };
  
  struct tcm_vhost_evt {
  	/* event to be sent to guest */
  	struct virtio_scsi_event event;
  	/* event list, serviced from vhost worker thread */
  	struct llist_node list;
  };

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

  enum {

  	VHOST_SCSI_FEATURES = VHOST_FEATURES | (1ULL << VIRTIO_SCSI_F_HOTPLUG) |
  					       (1ULL << VIRTIO_SCSI_F_T10_PI)

  };

  #define VHOST_SCSI_MAX_TARGET	256
  #define VHOST_SCSI_MAX_VQ	128

  #define VHOST_SCSI_MAX_EVENT	128

  struct vhost_scsi_virtqueue {
  	struct vhost_virtqueue vq;

  	/*
  	 * Reference counting for inflight reqs, used for flush operation. At
  	 * each time, one reference tracks new commands submitted, while we
  	 * wait for another one to reach 0.
  	 */

  	struct vhost_scsi_inflight inflights[2];

  	/*
  	 * Indicate current inflight in use, protected by vq->mutex.
  	 * Writers must also take dev mutex and flush under it.
  	 */

  	int inflight_idx;

  };

  struct vhost_scsi {

  	/* Protected by vhost_scsi->dev.mutex */

  	struct tcm_vhost_tpg **vs_tpg;

  	char vs_vhost_wwpn[TRANSPORT_IQN_LEN];

  	struct vhost_dev dev;

  	struct vhost_scsi_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 */

  
  	struct vhost_work vs_event_work; /* evt injection work item */
  	struct llist_head vs_event_list; /* evt injection queue */
  
  	bool vs_events_missed; /* any missed events, protected by vq->mutex */
  	int vs_events_nr; /* num of pending events, protected by vq->mutex */

  };
  
  /* 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 void tcm_vhost_done_inflight(struct kref *kref)

  {
  	struct vhost_scsi_inflight *inflight;
  
  	inflight = container_of(kref, struct vhost_scsi_inflight, kref);
  	complete(&inflight->comp);
  }
  
  static void tcm_vhost_init_inflight(struct vhost_scsi *vs,
  				    struct vhost_scsi_inflight *old_inflight[])
  {
  	struct vhost_scsi_inflight *new_inflight;
  	struct vhost_virtqueue *vq;
  	int idx, i;
  
  	for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
  		vq = &vs->vqs[i].vq;
  
  		mutex_lock(&vq->mutex);
  
  		/* store old infight */
  		idx = vs->vqs[i].inflight_idx;
  		if (old_inflight)
  			old_inflight[i] = &vs->vqs[i].inflights[idx];
  
  		/* setup new infight */
  		vs->vqs[i].inflight_idx = idx ^ 1;
  		new_inflight = &vs->vqs[i].inflights[idx ^ 1];
  		kref_init(&new_inflight->kref);
  		init_completion(&new_inflight->comp);
  
  		mutex_unlock(&vq->mutex);
  	}
  }
  
  static struct vhost_scsi_inflight *
  tcm_vhost_get_inflight(struct vhost_virtqueue *vq)
  {
  	struct vhost_scsi_inflight *inflight;
  	struct vhost_scsi_virtqueue *svq;
  
  	svq = container_of(vq, struct vhost_scsi_virtqueue, vq);
  	inflight = &svq->inflights[svq->inflight_idx];
  	kref_get(&inflight->kref);
  
  	return inflight;
  }
  
  static void tcm_vhost_put_inflight(struct vhost_scsi_inflight *inflight)
  {
  	kref_put(&inflight->kref, tcm_vhost_done_inflight);
  }

  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
  ", 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
  ", 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
  ", 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
  ", 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
  ");

  		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)
  {

  	struct tcm_vhost_cmd *tv_cmd = container_of(se_cmd,
  				struct tcm_vhost_cmd, tvc_se_cmd);

  	struct se_session *se_sess = se_cmd->se_sess;

  	int i;

  
  	if (tv_cmd->tvc_sgl_count) {

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

  	}

  	if (tv_cmd->tvc_prot_sgl_count) {
  		for (i = 0; i < tv_cmd->tvc_prot_sgl_count; i++)
  			put_page(sg_page(&tv_cmd->tvc_prot_sgl[i]));
  	}

  
  	tcm_vhost_put_inflight(tv_cmd->inflight);

  	percpu_ida_free(&se_sess->sess_tag_pool, se_cmd->map_tag);

  }
  
  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 *cmd)

  {

  	struct vhost_scsi *vs = cmd->tvc_vhost;

  	llist_add(&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 *cmd = container_of(se_cmd,

  				struct tcm_vhost_cmd, tvc_se_cmd);

  	vhost_scsi_complete_cmd(cmd);

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

  	struct tcm_vhost_cmd *cmd = container_of(se_cmd,

  				struct tcm_vhost_cmd, tvc_se_cmd);

  	vhost_scsi_complete_cmd(cmd);

  	return 0;
  }

  static void tcm_vhost_queue_tm_rsp(struct se_cmd *se_cmd)

  {

  	return;

  }

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

  static void tcm_vhost_free_evt(struct vhost_scsi *vs, struct tcm_vhost_evt *evt)
  {
  	vs->vs_events_nr--;
  	kfree(evt);
  }

  static struct tcm_vhost_evt *
  tcm_vhost_allocate_evt(struct vhost_scsi *vs,
  		       u32 event, u32 reason)

  {

  	struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;

  	struct tcm_vhost_evt *evt;
  
  	if (vs->vs_events_nr > VHOST_SCSI_MAX_EVENT) {
  		vs->vs_events_missed = true;
  		return NULL;
  	}
  
  	evt = kzalloc(sizeof(*evt), GFP_KERNEL);
  	if (!evt) {
  		vq_err(vq, "Failed to allocate tcm_vhost_evt
  ");
  		vs->vs_events_missed = true;
  		return NULL;
  	}
  
  	evt->event.event = event;
  	evt->event.reason = reason;
  	vs->vs_events_nr++;
  
  	return evt;
  }

  static void vhost_scsi_free_cmd(struct tcm_vhost_cmd *cmd)

  {

  	struct se_cmd *se_cmd = &cmd->tvc_se_cmd;

  
  	/* TODO locking against target/backend threads? */

  	transport_generic_free_cmd(se_cmd, 0);

  }

  static int vhost_scsi_check_stop_free(struct se_cmd *se_cmd)
  {
  	return target_put_sess_cmd(se_cmd->se_sess, se_cmd);

  }

  static void
  tcm_vhost_do_evt_work(struct vhost_scsi *vs, struct tcm_vhost_evt *evt)

  {

  	struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;

  	struct virtio_scsi_event *event = &evt->event;
  	struct virtio_scsi_event __user *eventp;
  	unsigned out, in;
  	int head, ret;
  
  	if (!vq->private_data) {
  		vs->vs_events_missed = true;
  		return;
  	}
  
  again:
  	vhost_disable_notify(&vs->dev, vq);

  	head = vhost_get_vq_desc(vq, vq->iov,

  			ARRAY_SIZE(vq->iov), &out, &in,
  			NULL, NULL);
  	if (head < 0) {
  		vs->vs_events_missed = true;
  		return;
  	}
  	if (head == vq->num) {
  		if (vhost_enable_notify(&vs->dev, vq))
  			goto again;
  		vs->vs_events_missed = true;
  		return;
  	}
  
  	if ((vq->iov[out].iov_len != sizeof(struct virtio_scsi_event))) {
  		vq_err(vq, "Expecting virtio_scsi_event, got %zu bytes
  ",
  				vq->iov[out].iov_len);
  		vs->vs_events_missed = true;
  		return;
  	}
  
  	if (vs->vs_events_missed) {
  		event->event |= VIRTIO_SCSI_T_EVENTS_MISSED;
  		vs->vs_events_missed = false;
  	}
  
  	eventp = vq->iov[out].iov_base;
  	ret = __copy_to_user(eventp, event, sizeof(*event));
  	if (!ret)
  		vhost_add_used_and_signal(&vs->dev, vq, head, 0);
  	else
  		vq_err(vq, "Faulted on tcm_vhost_send_event
  ");
  }
  
  static void tcm_vhost_evt_work(struct vhost_work *work)
  {
  	struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
  					vs_event_work);

  	struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;

  	struct tcm_vhost_evt *evt;
  	struct llist_node *llnode;
  
  	mutex_lock(&vq->mutex);
  	llnode = llist_del_all(&vs->vs_event_list);
  	while (llnode) {
  		evt = llist_entry(llnode, struct tcm_vhost_evt, list);
  		llnode = llist_next(llnode);
  		tcm_vhost_do_evt_work(vs, evt);
  		tcm_vhost_free_evt(vs, evt);
  	}
  	mutex_unlock(&vq->mutex);
  }

  /* 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 *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) {

  		cmd = llist_entry(llnode, struct tcm_vhost_cmd,

  				     tvc_completion_list);
  		llnode = llist_next(llnode);

  		se_cmd = &cmd->tvc_se_cmd;

  
  		pr_debug("%s tv_cmd %p resid %u status %#02x
  ", __func__,

  			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, cmd->tvc_sense_buf,

  		       v_rsp.sense_len);

  		ret = copy_to_user(cmd->tvc_resp, &v_rsp, sizeof(v_rsp));

  		if (likely(ret == 0)) {

  			struct vhost_scsi_virtqueue *q;

  			vhost_add_used(cmd->tvc_vq, cmd->tvc_vq_desc, 0);
  			q = container_of(cmd->tvc_vq, struct vhost_scsi_virtqueue, vq);

  			vq = q - vs->vqs;

  			__set_bit(vq, signal);
  		} else

  			pr_err("Faulted on virtio_scsi_cmd_resp
  ");

  		vhost_scsi_free_cmd(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].vq);

  }

  static struct tcm_vhost_cmd *

  vhost_scsi_get_tag(struct vhost_virtqueue *vq, struct tcm_vhost_tpg *tpg,
  		   unsigned char *cdb, u64 scsi_tag, u16 lun, u8 task_attr,
  		   u32 exp_data_len, int data_direction)

  {

  	struct tcm_vhost_cmd *cmd;

  	struct tcm_vhost_nexus *tv_nexus;

  	struct se_session *se_sess;

  	struct scatterlist *sg, *prot_sg;

  	struct page **pages;

  	int tag;

  	tv_nexus = tpg->tpg_nexus;

  	if (!tv_nexus) {
  		pr_err("Unable to locate active struct tcm_vhost_nexus
  ");
  		return ERR_PTR(-EIO);
  	}

  	se_sess = tv_nexus->tvn_se_sess;

  	tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);

  	if (tag < 0) {
  		pr_err("Unable to obtain tag for tcm_vhost_cmd
  ");
  		return ERR_PTR(-ENOMEM);
  	}

  	cmd = &((struct tcm_vhost_cmd *)se_sess->sess_cmd_map)[tag];

  	sg = cmd->tvc_sgl;

  	prot_sg = cmd->tvc_prot_sgl;

  	pages = cmd->tvc_upages;

  	memset(cmd, 0, sizeof(struct tcm_vhost_cmd));

  	cmd->tvc_sgl = sg;

  	cmd->tvc_prot_sgl = prot_sg;

  	cmd->tvc_upages = pages;

  	cmd->tvc_se_cmd.map_tag = tag;

  	cmd->tvc_tag = scsi_tag;
  	cmd->tvc_lun = lun;
  	cmd->tvc_task_attr = task_attr;

  	cmd->tvc_exp_data_len = exp_data_len;
  	cmd->tvc_data_direction = data_direction;
  	cmd->tvc_nexus = tv_nexus;
  	cmd->inflight = tcm_vhost_get_inflight(vq);

  	memcpy(cmd->tvc_cdb, cdb, TCM_VHOST_MAX_CDB_SIZE);

  	return 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 tcm_vhost_cmd *tv_cmd,
  		      struct scatterlist *sgl,

  		      unsigned int sgl_count,
  		      struct iovec *iov,

  		      struct page **pages,
  		      bool 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;

  	int ret, i;

  	pages_nr = iov_num_pages(iov);

  	if (pages_nr > sgl_count) {
  		pr_err("vhost_scsi_map_to_sgl() pages_nr: %u greater than"
  		       " sgl_count: %u
  ", pages_nr, sgl_count);

  		return -ENOBUFS;

  	}
  	if (pages_nr > TCM_VHOST_PREALLOC_UPAGES) {

  		pr_err("vhost_scsi_map_to_sgl() pages_nr: %u greater than"

  		       " preallocated TCM_VHOST_PREALLOC_UPAGES: %u
  ",
  			pages_nr, TCM_VHOST_PREALLOC_UPAGES);

  		return -ENOBUFS;
  	}

  	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:

  	return ret;
  }

  static int

  vhost_scsi_map_iov_to_sgl(struct tcm_vhost_cmd *cmd,

  			  struct iovec *iov,

  			  int niov,
  			  bool write)

  {

  	struct scatterlist *sg = cmd->tvc_sgl;
  	unsigned int sgl_count = 0;
  	int ret, i;

  	for (i = 0; i < niov; i++)
  		sgl_count += iov_num_pages(&iov[i]);

  	if (sgl_count > TCM_VHOST_PREALLOC_SGLS) {
  		pr_err("vhost_scsi_map_iov_to_sgl() sgl_count: %u greater than"
  			" preallocated TCM_VHOST_PREALLOC_SGLS: %u
  ",
  			sgl_count, TCM_VHOST_PREALLOC_SGLS);
  		return -ENOBUFS;
  	}

  	pr_debug("%s sg %p sgl_count %u
  ", __func__, sg, sgl_count);

  	sg_init_table(sg, sgl_count);

  	cmd->tvc_sgl_count = sgl_count;

  	pr_debug("Mapping iovec %p for %u pages
  ", &iov[0], sgl_count);

  	for (i = 0; i < niov; i++) {

  		ret = vhost_scsi_map_to_sgl(cmd, sg, sgl_count, &iov[i],

  					    cmd->tvc_upages, write);

  		if (ret < 0) {

  			for (i = 0; i < cmd->tvc_sgl_count; i++)
  				put_page(sg_page(&cmd->tvc_sgl[i]));

  			cmd->tvc_sgl_count = 0;

  			return ret;
  		}

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

  static int
  vhost_scsi_map_iov_to_prot(struct tcm_vhost_cmd *cmd,
  			   struct iovec *iov,
  			   int niov,
  			   bool write)
  {
  	struct scatterlist *prot_sg = cmd->tvc_prot_sgl;
  	unsigned int prot_sgl_count = 0;
  	int ret, i;
  
  	for (i = 0; i < niov; i++)
  		prot_sgl_count += iov_num_pages(&iov[i]);
  
  	if (prot_sgl_count > TCM_VHOST_PREALLOC_PROT_SGLS) {
  		pr_err("vhost_scsi_map_iov_to_prot() sgl_count: %u greater than"
  			" preallocated TCM_VHOST_PREALLOC_PROT_SGLS: %u
  ",
  			prot_sgl_count, TCM_VHOST_PREALLOC_PROT_SGLS);
  		return -ENOBUFS;
  	}
  
  	pr_debug("%s prot_sg %p prot_sgl_count %u
  ", __func__,
  		 prot_sg, prot_sgl_count);
  	sg_init_table(prot_sg, prot_sgl_count);
  	cmd->tvc_prot_sgl_count = prot_sgl_count;
  
  	for (i = 0; i < niov; i++) {
  		ret = vhost_scsi_map_to_sgl(cmd, prot_sg, prot_sgl_count, &iov[i],
  					    cmd->tvc_upages, write);
  		if (ret < 0) {
  			for (i = 0; i < cmd->tvc_prot_sgl_count; i++)
  				put_page(sg_page(&cmd->tvc_prot_sgl[i]));
  
  			cmd->tvc_prot_sgl_count = 0;
  			return ret;
  		}
  		prot_sg += ret;
  		prot_sgl_count -= ret;
  	}
  	return 0;
  }

  static void tcm_vhost_submission_work(struct work_struct *work)
  {

  	struct tcm_vhost_cmd *cmd =

  		container_of(work, struct tcm_vhost_cmd, work);

  	struct tcm_vhost_nexus *tv_nexus;

  	struct se_cmd *se_cmd = &cmd->tvc_se_cmd;

  	struct scatterlist *sg_ptr, *sg_prot_ptr = NULL;
  	int rc;

  	/* FIXME: BIDI operation */

  	if (cmd->tvc_sgl_count) {
  		sg_ptr = cmd->tvc_sgl;

  
  		if (cmd->tvc_prot_sgl_count)
  			sg_prot_ptr = cmd->tvc_prot_sgl;
  		else
  			se_cmd->prot_pto = true;

  	} else {
  		sg_ptr = NULL;
  	}

  	tv_nexus = cmd->tvc_nexus;

  
  	rc = target_submit_cmd_map_sgls(se_cmd, tv_nexus->tvn_se_sess,

  			cmd->tvc_cdb, &cmd->tvc_sense_buf[0],
  			cmd->tvc_lun, cmd->tvc_exp_data_len,
  			cmd->tvc_task_attr, cmd->tvc_data_direction,

  			TARGET_SCF_ACK_KREF, sg_ptr, cmd->tvc_sgl_count,

  			NULL, 0, sg_prot_ptr, cmd->tvc_prot_sgl_count);

  	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_send_bad_target(struct vhost_scsi *vs,
  			   struct vhost_virtqueue *vq,
  			   int head, unsigned out)

  {
  	struct virtio_scsi_cmd_resp __user *resp;
  	struct virtio_scsi_cmd_resp rsp;
  	int ret;
  
  	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
  ");
  }

  static void
  vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)

  {

  	struct tcm_vhost_tpg **vs_tpg;

  	struct virtio_scsi_cmd_req v_req;

  	struct virtio_scsi_cmd_req_pi v_req_pi;

  	struct tcm_vhost_tpg *tpg;

  	struct tcm_vhost_cmd *cmd;

  	u64 tag;
  	u32 exp_data_len, data_first, data_num, data_direction, prot_first;

  	unsigned out, in, i;

  	int head, ret, data_niov, prot_niov, prot_bytes;
  	size_t req_size;
  	u16 lun;
  	u8 *target, *lunp, task_attr;
  	bool hdr_pi;
  	void *req, *cdb;

  	mutex_lock(&vq->mutex);

  	/*
  	 * We can handle the vq only after the endpoint is setup by calling the
  	 * VHOST_SCSI_SET_ENDPOINT ioctl.

  	 */

  	vs_tpg = vq->private_data;

  	if (!vs_tpg)

  		goto out;

  	vhost_disable_notify(&vs->dev, vq);
  
  	for (;;) {

  		head = vhost_get_vq_desc(vq, vq->iov,

  					ARRAY_SIZE(vq->iov), &out, &in,
  					NULL, NULL);
  		pr_debug("vhost_get_vq_desc: head: %d, out: %u in: %u
  ",
  					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
  ",
  					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
  ", vq->iov[out].iov_len);
  			break;
  		}

  		if (vhost_has_feature(vq, VIRTIO_SCSI_F_T10_PI)) {

  			req = &v_req_pi;
  			lunp = &v_req_pi.lun[0];
  			target = &v_req_pi.lun[1];
  			req_size = sizeof(v_req_pi);
  			hdr_pi = true;
  		} else {
  			req = &v_req;
  			lunp = &v_req.lun[0];
  			target = &v_req.lun[1];
  			req_size = sizeof(v_req);
  			hdr_pi = false;
  		}
  
  		if (unlikely(vq->iov[0].iov_len < req_size)) {
  			pr_err("Expecting virtio-scsi header: %zu, got %zu
  ",
  			       req_size, vq->iov[0].iov_len);

  			break;
  		}

  		ret = memcpy_fromiovecend(req, &vq->iov[0], 0, req_size);

  		if (unlikely(ret)) {
  			vq_err(vq, "Faulted on virtio_scsi_cmd_req
  ");
  			break;
  		}

  		/* virtio-scsi spec requires byte 0 of the lun to be 1 */

  		if (unlikely(*lunp != 1)) {

  			vhost_scsi_send_bad_target(vs, vq, head, out);
  			continue;
  		}

  		tpg = ACCESS_ONCE(vs_tpg[*target]);

  
  		/* Target does not exist, fail the request */

  		if (unlikely(!tpg)) {

  			vhost_scsi_send_bad_target(vs, vq, head, out);

  			continue;
  		}

  		data_niov = data_num;
  		prot_niov = prot_first = prot_bytes = 0;
  		/*
  		 * Determine if any protection information iovecs are preceeding
  		 * the actual data payload, and adjust data_first + data_niov
  		 * values accordingly for vhost_scsi_map_iov_to_sgl() below.
  		 *
  		 * Also extract virtio_scsi header bits for vhost_scsi_get_tag()
  		 */
  		if (hdr_pi) {
  			if (v_req_pi.pi_bytesout) {
  				if (data_direction != DMA_TO_DEVICE) {
  					vq_err(vq, "Received non zero do_pi_niov"
  						", but wrong data_direction
  ");
  					goto err_cmd;
  				}
  				prot_bytes = v_req_pi.pi_bytesout;
  			} else if (v_req_pi.pi_bytesin) {
  				if (data_direction != DMA_FROM_DEVICE) {
  					vq_err(vq, "Received non zero di_pi_niov"
  						", but wrong data_direction
  ");
  					goto err_cmd;
  				}
  				prot_bytes = v_req_pi.pi_bytesin;
  			}
  			if (prot_bytes) {
  				int tmp = 0;
  
  				for (i = 0; i < data_num; i++) {
  					tmp += vq->iov[data_first + i].iov_len;
  					prot_niov++;
  					if (tmp >= prot_bytes)
  						break;
  				}
  				prot_first = data_first;
  				data_first += prot_niov;
  				data_niov = data_num - prot_niov;
  			}
  			tag = v_req_pi.tag;
  			task_attr = v_req_pi.task_attr;
  			cdb = &v_req_pi.cdb[0];
  			lun = ((v_req_pi.lun[2] << 8) | v_req_pi.lun[3]) & 0x3FFF;
  		} else {
  			tag = v_req.tag;
  			task_attr = v_req.task_attr;
  			cdb = &v_req.cdb[0];
  			lun = ((v_req.lun[2] << 8) | v_req.lun[3]) & 0x3FFF;
  		}

  		exp_data_len = 0;

  		for (i = 0; i < data_niov; i++)

  			exp_data_len += vq->iov[data_first + i].iov_len;

  		/*
  		 * Check that the recieved CDB size does not exceeded our
  		 * hardcoded max for vhost-scsi
  		 *
  		 * TODO what if cdb was too small for varlen cdb header?
  		 */
  		if (unlikely(scsi_command_size(cdb) > TCM_VHOST_MAX_CDB_SIZE)) {
  			vq_err(vq, "Received SCSI CDB with command_size: %d that"
  				" exceeds SCSI_MAX_VARLEN_CDB_SIZE: %d
  ",
  				scsi_command_size(cdb), TCM_VHOST_MAX_CDB_SIZE);
  			goto err_cmd;
  		}

  		cmd = vhost_scsi_get_tag(vq, tpg, cdb, tag, lun, task_attr,

  					 exp_data_len + prot_bytes,
  					 data_direction);

  		if (IS_ERR(cmd)) {

  			vq_err(vq, "vhost_scsi_get_tag failed %ld
  ",

  					PTR_ERR(cmd));

  			goto err_cmd;

  		}

  		pr_debug("Allocated tv_cmd: %p exp_data_len: %d, data_direction"

  			": %d
  ", cmd, exp_data_len, data_direction);

  		cmd->tvc_vhost = vs;
  		cmd->tvc_vq = vq;
  		cmd->tvc_resp = vq->iov[out].iov_base;

  		pr_debug("vhost_scsi got command opcode: %#02x, lun: %d
  ",

  			cmd->tvc_cdb[0], cmd->tvc_lun);

  		if (prot_niov) {
  			ret = vhost_scsi_map_iov_to_prot(cmd,
  					&vq->iov[prot_first], prot_niov,
  					data_direction == DMA_FROM_DEVICE);
  			if (unlikely(ret)) {
  				vq_err(vq, "Failed to map iov to"
  					" prot_sgl
  ");
  				goto err_free;
  			}
  		}

  		if (data_direction != DMA_NONE) {

  			ret = vhost_scsi_map_iov_to_sgl(cmd,

  					&vq->iov[data_first], data_niov,

  					data_direction == DMA_FROM_DEVICE);

  			if (unlikely(ret)) {
  				vq_err(vq, "Failed to map iov to sgl
  ");

  				goto err_free;

  			}
  		}

  		/*
  		 * 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()
  		 */

  		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(&cmd->work, tcm_vhost_submission_work);
  		queue_work(tcm_vhost_workqueue, &cmd->work);

  	}
  
  	mutex_unlock(&vq->mutex);

  	return;

  err_free:

  	vhost_scsi_free_cmd(cmd);

  err_cmd:
  	vhost_scsi_send_bad_target(vs, vq, head, out);

  out:

  	mutex_unlock(&vq->mutex);

  }
  
  static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
  {

  	pr_debug("%s: The handling func for control queue.
  ", __func__);

  }

  static void
  tcm_vhost_send_evt(struct vhost_scsi *vs,
  		   struct tcm_vhost_tpg *tpg,
  		   struct se_lun *lun,
  		   u32 event,
  		   u32 reason)

  {
  	struct tcm_vhost_evt *evt;
  
  	evt = tcm_vhost_allocate_evt(vs, event, reason);
  	if (!evt)
  		return;
  
  	if (tpg && lun) {
  		/* TODO: share lun setup code with virtio-scsi.ko */
  		/*
  		 * Note: evt->event is zeroed when we allocate it and
  		 * lun[4-7] need to be zero according to virtio-scsi spec.
  		 */
  		evt->event.lun[0] = 0x01;
  		evt->event.lun[1] = tpg->tport_tpgt & 0xFF;
  		if (lun->unpacked_lun >= 256)
  			evt->event.lun[2] = lun->unpacked_lun >> 8 | 0x40 ;
  		evt->event.lun[3] = lun->unpacked_lun & 0xFF;
  	}
  
  	llist_add(&evt->list, &vs->vs_event_list);
  	vhost_work_queue(&vs->dev, &vs->vs_event_work);
  }

  static void vhost_scsi_evt_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);
  
  	mutex_lock(&vq->mutex);
  	if (!vq->private_data)
  		goto out;
  
  	if (vs->vs_events_missed)
  		tcm_vhost_send_evt(vs, NULL, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
  out:
  	mutex_unlock(&vq->mutex);

  }
  
  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);

  }

  static void vhost_scsi_flush_vq(struct vhost_scsi *vs, int index)
  {

  	vhost_poll_flush(&vs->vqs[index].vq.poll);

  }

  /* Callers must hold dev mutex */

  static void vhost_scsi_flush(struct vhost_scsi *vs)
  {

  	struct vhost_scsi_inflight *old_inflight[VHOST_SCSI_MAX_VQ];

  	int i;

  	/* Init new inflight and remember the old inflight */
  	tcm_vhost_init_inflight(vs, old_inflight);
  
  	/*
  	 * The inflight->kref was initialized to 1. We decrement it here to
  	 * indicate the start of the flush operation so that it will reach 0
  	 * when all the reqs are finished.
  	 */
  	for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
  		kref_put(&old_inflight[i]->kref, tcm_vhost_done_inflight);
  
  	/* Flush both the vhost poll and vhost work */

  	for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
  		vhost_scsi_flush_vq(vs, i);
  	vhost_work_flush(&vs->dev, &vs->vs_completion_work);

  	vhost_work_flush(&vs->dev, &vs->vs_event_work);

  
  	/* Wait for all reqs issued before the flush to be finished */
  	for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
  		wait_for_completion(&old_inflight[i]->comp);

  }

  /*
   * Called from vhost_scsi_ioctl() context to walk the list of available
   * tcm_vhost_tpg with an active struct tcm_vhost_nexus

   *
   *  The lock nesting rule is:
   *    tcm_vhost_mutex -> vs->dev.mutex -> tpg->tv_tpg_mutex -> vq->mutex

   */

  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 *tpg;

  	struct tcm_vhost_tpg **vs_tpg;
  	struct vhost_virtqueue *vq;
  	int index, ret, i, len;

  	bool match = false;

  	mutex_lock(&tcm_vhost_mutex);

  	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].vq)) {

  			ret = -EFAULT;
  			goto out;

  		}
  	}

  	len = sizeof(vs_tpg[0]) * VHOST_SCSI_MAX_TARGET;
  	vs_tpg = kzalloc(len, GFP_KERNEL);
  	if (!vs_tpg) {

  		ret = -ENOMEM;
  		goto out;

  	}
  	if (vs->vs_tpg)
  		memcpy(vs_tpg, vs->vs_tpg, len);

  	list_for_each_entry(tpg, &tcm_vhost_list, tv_tpg_list) {
  		mutex_lock(&tpg->tv_tpg_mutex);
  		if (!tpg->tpg_nexus) {
  			mutex_unlock(&tpg->tv_tpg_mutex);

  			continue;
  		}

  		if (tpg->tv_tpg_vhost_count != 0) {
  			mutex_unlock(&tpg->tv_tpg_mutex);

  			continue;
  		}

  		tv_tport = tpg->tport;

  		if (!strcmp(tv_tport->tport_name, t->vhost_wwpn)) {

  			if (vs->vs_tpg && vs->vs_tpg[tpg->tport_tpgt]) {

  				kfree(vs_tpg);

  				mutex_unlock(&tpg->tv_tpg_mutex);

  				ret = -EEXIST;
  				goto out;

  			}

  			tpg->tv_tpg_vhost_count++;
  			tpg->vhost_scsi = vs;
  			vs_tpg[tpg->tport_tpgt] = tpg;

  			smp_mb__after_atomic();

  			match = true;

  		}

  		mutex_unlock(&tpg->tv_tpg_mutex);

  	}

  
  	if (match) {
  		memcpy(vs->vs_vhost_wwpn, t->vhost_wwpn,
  		       sizeof(vs->vs_vhost_wwpn));

  		for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {

  			vq = &vs->vqs[i].vq;

  			mutex_lock(&vq->mutex);

  			vq->private_data = vs_tpg;

  			vhost_init_used(vq);

  			mutex_unlock(&vq->mutex);
  		}

  		ret = 0;
  	} else {
  		ret = -EEXIST;
  	}

  	/*
  	 * Act as synchronize_rcu to make sure access to
  	 * old vs->vs_tpg is finished.
  	 */
  	vhost_scsi_flush(vs);
  	kfree(vs->vs_tpg);
  	vs->vs_tpg = vs_tpg;

  out:

  	mutex_unlock(&vs->dev.mutex);

  	mutex_unlock(&tcm_vhost_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 *tpg;

  	struct vhost_virtqueue *vq;
  	bool match = false;

  	int index, ret, i;
  	u8 target;

  	mutex_lock(&tcm_vhost_mutex);

  	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].vq)) {

  			ret = -EFAULT;

  			goto err_dev;

  		}
  	}

  
  	if (!vs->vs_tpg) {

  		ret = 0;
  		goto err_dev;

  	}

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

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

  			continue;

  		mutex_lock(&tpg->tv_tpg_mutex);
  		tv_tport = tpg->tport;

  		if (!tv_tport) {
  			ret = -ENODEV;

  			goto err_tpg;

  		}
  
  		if (strcmp(tv_tport->tport_name, t->vhost_wwpn)) {

  			pr_warn("tv_tport->tport_name: %s, tpg->tport_tpgt: %hu"

  				" does not match t->vhost_wwpn: %s, t->vhost_tpgt: %hu
  ",

  				tv_tport->tport_name, tpg->tport_tpgt,

  				t->vhost_wwpn, t->vhost_tpgt);
  			ret = -EINVAL;

  			goto err_tpg;

  		}

  		tpg->tv_tpg_vhost_count--;
  		tpg->vhost_scsi = NULL;

  		vs->vs_tpg[target] = NULL;

  		match = true;

  		mutex_unlock(&tpg->tv_tpg_mutex);

  	}

  	if (match) {
  		for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {

  			vq = &vs->vqs[i].vq;

  			mutex_lock(&vq->mutex);

  			vq->private_data = NULL;

  			mutex_unlock(&vq->mutex);
  		}
  	}
  	/*
  	 * Act as synchronize_rcu to make sure access to
  	 * old vs->vs_tpg is finished.
  	 */
  	vhost_scsi_flush(vs);
  	kfree(vs->vs_tpg);
  	vs->vs_tpg = NULL;

  	WARN_ON(vs->vs_events_nr);

  	mutex_unlock(&vs->dev.mutex);

  	mutex_unlock(&tcm_vhost_mutex);

  	return 0;

  err_tpg:

  	mutex_unlock(&tpg->tv_tpg_mutex);

  err_dev:

  	mutex_unlock(&vs->dev.mutex);

  	mutex_unlock(&tcm_vhost_mutex);

  	return ret;

  }

  static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
  {

  	struct vhost_virtqueue *vq;
  	int i;

  	if (features & ~VHOST_SCSI_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;
  	}

  
  	for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
  		vq = &vs->vqs[i].vq;
  		mutex_lock(&vq->mutex);
  		vq->acked_features = features;
  		mutex_unlock(&vq->mutex);
  	}

  	mutex_unlock(&vs->dev.mutex);
  	return 0;
  }

  static int vhost_scsi_open(struct inode *inode, struct file *f)
  {

  	struct vhost_scsi *vs;

  	struct vhost_virtqueue **vqs;

  	int r = -ENOMEM, i;

  	vs = kzalloc(sizeof(*vs), GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
  	if (!vs) {
  		vs = vzalloc(sizeof(*vs));
  		if (!vs)
  			goto err_vs;
  	}

  	vqs = kmalloc(VHOST_SCSI_MAX_VQ * sizeof(*vqs), GFP_KERNEL);

  	if (!vqs)
  		goto err_vqs;

  	vhost_work_init(&vs->vs_completion_work, vhost_scsi_complete_cmd_work);
  	vhost_work_init(&vs->vs_event_work, tcm_vhost_evt_work);

  	vs->vs_events_nr = 0;
  	vs->vs_events_missed = false;

  	vqs[VHOST_SCSI_VQ_CTL] = &vs->vqs[VHOST_SCSI_VQ_CTL].vq;
  	vqs[VHOST_SCSI_VQ_EVT] = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
  	vs->vqs[VHOST_SCSI_VQ_CTL].vq.handle_kick = vhost_scsi_ctl_handle_kick;
  	vs->vqs[VHOST_SCSI_VQ_EVT].vq.handle_kick = vhost_scsi_evt_handle_kick;

  	for (i = VHOST_SCSI_VQ_IO; i < VHOST_SCSI_MAX_VQ; i++) {

  		vqs[i] = &vs->vqs[i].vq;
  		vs->vqs[i].vq.handle_kick = vhost_scsi_handle_kick;

  	}

  	vhost_dev_init(&vs->dev, vqs, VHOST_SCSI_MAX_VQ);

  	tcm_vhost_init_inflight(vs, NULL);

  	f->private_data = vs;

  	return 0;

  err_vqs:

  	kvfree(vs);

  err_vs:
  	return r;

  }
  
  static int vhost_scsi_release(struct inode *inode, struct file *f)
  {

  	struct vhost_scsi *vs = f->private_data;

  	struct vhost_scsi_target t;

  	mutex_lock(&vs->dev.mutex);
  	memcpy(t.vhost_wwpn, vs->vs_vhost_wwpn, sizeof(t.vhost_wwpn));
  	mutex_unlock(&vs->dev.mutex);
  	vhost_scsi_clear_endpoint(vs, &t);
  	vhost_dev_stop(&vs->dev);
  	vhost_dev_cleanup(&vs->dev, false);

  	/* Jobs can re-queue themselves in evt kick handler. Do extra flush. */

  	vhost_scsi_flush(vs);
  	kfree(vs->dev.vqs);

  	kvfree(vs);

  	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;

  	u32 __user *eventsp = argp;
  	u32 events_missed;

  	u64 features;

  	int r, abi_version = VHOST_SCSI_ABI_VERSION;

  	struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;

  
  	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_SCSI_SET_EVENTS_MISSED:
  		if (get_user(events_missed, eventsp))
  			return -EFAULT;
  		mutex_lock(&vq->mutex);
  		vs->vs_events_missed = events_missed;
  		mutex_unlock(&vq->mutex);
  		return 0;
  	case VHOST_SCSI_GET_EVENTS_MISSED:
  		mutex_lock(&vq->mutex);
  		events_missed = vs->vs_events_missed;
  		mutex_unlock(&vq->mutex);
  		if (put_user(events_missed, eventsp))
  			return -EFAULT;
  		return 0;

  	case VHOST_GET_FEATURES:

  		features = VHOST_SCSI_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 void
  tcm_vhost_do_plug(struct tcm_vhost_tpg *tpg,
  		  struct se_lun *lun, bool plug)

  {
  
  	struct vhost_scsi *vs = tpg->vhost_scsi;
  	struct vhost_virtqueue *vq;
  	u32 reason;
  
  	if (!vs)
  		return;
  
  	mutex_lock(&vs->dev.mutex);

  
  	if (plug)
  		reason = VIRTIO_SCSI_EVT_RESET_RESCAN;
  	else
  		reason = VIRTIO_SCSI_EVT_RESET_REMOVED;

  	vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;

  	mutex_lock(&vq->mutex);

  	if (vhost_has_feature(vq, VIRTIO_SCSI_F_HOTPLUG))
  		tcm_vhost_send_evt(vs, tpg, lun,
  				   VIRTIO_SCSI_T_TRANSPORT_RESET, reason);

  	mutex_unlock(&vq->mutex);
  	mutex_unlock(&vs->dev.mutex);
  }
  
  static void tcm_vhost_hotplug(struct tcm_vhost_tpg *tpg, struct se_lun *lun)
  {
  	tcm_vhost_do_plug(tpg, lun, true);
  }
  
  static void tcm_vhost_hotunplug(struct tcm_vhost_tpg *tpg, struct se_lun *lun)
  {
  	tcm_vhost_do_plug(tpg, lun, false);
  }

  static int tcm_vhost_port_link(struct se_portal_group *se_tpg,

  			       struct se_lun *lun)

  {

  	struct tcm_vhost_tpg *tpg = container_of(se_tpg,

  				struct tcm_vhost_tpg, se_tpg);

  	mutex_lock(&tcm_vhost_mutex);

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

  	tcm_vhost_hotplug(tpg, lun);

  
  	mutex_unlock(&tcm_vhost_mutex);

  	return 0;
  }

  static void tcm_vhost_port_unlink(struct se_portal_group *se_tpg,

  				  struct se_lun *lun)

  {

  	struct tcm_vhost_tpg *tpg = container_of(se_tpg,

  				struct tcm_vhost_tpg, se_tpg);

  	mutex_lock(&tcm_vhost_mutex);

  	mutex_lock(&tpg->tv_tpg_mutex);
  	tpg->tv_tpg_port_count--;
  	mutex_unlock(&tpg->tv_tpg_mutex);

  	tcm_vhost_hotunplug(tpg, lun);

  
  	mutex_unlock(&tcm_vhost_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 void tcm_vhost_free_cmd_map_res(struct tcm_vhost_nexus *nexus,
  				       struct se_session *se_sess)
  {
  	struct tcm_vhost_cmd *tv_cmd;
  	unsigned int i;
  
  	if (!se_sess->sess_cmd_map)
  		return;
  
  	for (i = 0; i < TCM_VHOST_DEFAULT_TAGS; i++) {
  		tv_cmd = &((struct tcm_vhost_cmd *)se_sess->sess_cmd_map)[i];
  
  		kfree(tv_cmd->tvc_sgl);

  		kfree(tv_cmd->tvc_prot_sgl);

  		kfree(tv_cmd->tvc_upages);
  	}
  }

  static int tcm_vhost_make_nexus(struct tcm_vhost_tpg *tpg,

  				const char *name)

  {
  	struct se_portal_group *se_tpg;

  	struct se_session *se_sess;

  	struct tcm_vhost_nexus *tv_nexus;

  	struct tcm_vhost_cmd *tv_cmd;
  	unsigned int i;

  	mutex_lock(&tpg->tv_tpg_mutex);
  	if (tpg->tpg_nexus) {
  		mutex_unlock(&tpg->tv_tpg_mutex);
  		pr_debug("tpg->tpg_nexus already exists
  ");

  		return -EEXIST;
  	}

  	se_tpg = &tpg->se_tpg;

  
  	tv_nexus = kzalloc(sizeof(struct tcm_vhost_nexus), GFP_KERNEL);
  	if (!tv_nexus) {

  		mutex_unlock(&tpg->tv_tpg_mutex);

  		pr_err("Unable to allocate struct tcm_vhost_nexus
  ");
  		return -ENOMEM;
  	}
  	/*

  	 *  Initialize the struct se_session pointer and setup tagpool
  	 *  for struct tcm_vhost_cmd descriptors

  	 */

  	tv_nexus->tvn_se_sess = transport_init_session_tags(
  					TCM_VHOST_DEFAULT_TAGS,

  					sizeof(struct tcm_vhost_cmd),

  					TARGET_PROT_DIN_PASS | TARGET_PROT_DOUT_PASS);

  	if (IS_ERR(tv_nexus->tvn_se_sess)) {

  		mutex_unlock(&tpg->tv_tpg_mutex);

  		kfree(tv_nexus);
  		return -ENOMEM;
  	}

  	se_sess = tv_nexus->tvn_se_sess;
  	for (i = 0; i < TCM_VHOST_DEFAULT_TAGS; i++) {
  		tv_cmd = &((struct tcm_vhost_cmd *)se_sess->sess_cmd_map)[i];
  
  		tv_cmd->tvc_sgl = kzalloc(sizeof(struct scatterlist) *
  					TCM_VHOST_PREALLOC_SGLS, GFP_KERNEL);
  		if (!tv_cmd->tvc_sgl) {
  			mutex_unlock(&tpg->tv_tpg_mutex);
  			pr_err("Unable to allocate tv_cmd->tvc_sgl
  ");
  			goto out;
  		}
  
  		tv_cmd->tvc_upages = kzalloc(sizeof(struct page *) *

  					TCM_VHOST_PREALLOC_UPAGES, GFP_KERNEL);

  		if (!tv_cmd->tvc_upages) {
  			mutex_unlock(&tpg->tv_tpg_mutex);
  			pr_err("Unable to allocate tv_cmd->tvc_upages
  ");
  			goto out;
  		}

  
  		tv_cmd->tvc_prot_sgl = kzalloc(sizeof(struct scatterlist) *
  					TCM_VHOST_PREALLOC_PROT_SGLS, GFP_KERNEL);
  		if (!tv_cmd->tvc_prot_sgl) {
  			mutex_unlock(&tpg->tv_tpg_mutex);
  			pr_err("Unable to allocate tv_cmd->tvc_prot_sgl
  ");
  			goto out;
  		}

  	}

  	/*
  	 * 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(&tpg->tv_tpg_mutex);

  		pr_debug("core_tpg_check_initiator_node_acl() failed"
  				" for %s
  ", name);

  		goto out;

  	}
  	/*

  	 * 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);

  	tpg->tpg_nexus = tv_nexus;

  	mutex_unlock(&tpg->tv_tpg_mutex);

  	return 0;

  
  out:
  	tcm_vhost_free_cmd_map_res(tv_nexus, se_sess);
  	transport_free_session(se_sess);
  	kfree(tv_nexus);
  	return -ENOMEM;

  }

  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
  ",

  			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
  ",

  			tpg->tv_tpg_vhost_count);
  		return -EBUSY;

  	}

  	pr_debug("TCM_vhost_ConfigFS: Removing I_T Nexus to emulated"

  		" %s Initiator Port: %s
  ", tcm_vhost_dump_proto_id(tpg->tport),
  		tv_nexus->tvn_se_sess->se_node_acl->initiatorname);

  
  	tcm_vhost_free_cmd_map_res(tv_nexus, se_sess);

  	/*

  	 * 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 *tpg = container_of(se_tpg,

  				struct tcm_vhost_tpg, se_tpg);
  	struct tcm_vhost_nexus *tv_nexus;
  	ssize_t ret;

  	mutex_lock(&tpg->tv_tpg_mutex);
  	tv_nexus = tpg->tpg_nexus;

  	if (!tv_nexus) {

  		mutex_unlock(&tpg->tv_tpg_mutex);

  		return -ENODEV;
  	}
  	ret = snprintf(page, PAGE_SIZE, "%s
  ",
  			tv_nexus->tvn_se_sess->se_node_acl->initiatorname);

  	mutex_unlock(&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 *tpg = container_of(se_tpg,

  				struct tcm_vhost_tpg, se_tpg);

  	struct tcm_vhost_tport *tport_wwn = 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(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
  ", 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
  ", 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
  ", 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
  ", 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
  ", i_port);
  	return -EINVAL;
  	/*
  	 * Clear any trailing newline for the NAA WWN
  	 */
  check_newline:
  	if (i_port[strlen(i_port)-1] == '
  ')
  		i_port[strlen(i_port)-1] = '\0';

  	ret = tcm_vhost_make_nexus(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
  ", name);
  	kfree(tport);
  	return ERR_PTR(-EINVAL);
  
  check_len:
  	if (strlen(name) >= TCM_VHOST_NAMELEN) {
  		pr_err("Emulated %s Address: %s, exceeds"
  			" max: %d
  ", 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
  ", 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
  ", 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"
  ", 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,

  	.check_stop_free		= vhost_scsi_check_stop_free,

  	.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,

  	.aborted_task			= tcm_vhost_aborted_task,

  	/*
  	 * 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"
  ", 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
  ");
  		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
  	 */

  	fabric->tf_cit_tmpl.tfc_wwn_cit.ct_attrs = tcm_vhost_wwn_attrs;
  	fabric->tf_cit_tmpl.tfc_tpg_base_cit.ct_attrs = tcm_vhost_tpg_attrs;
  	fabric->tf_cit_tmpl.tfc_tpg_attrib_cit.ct_attrs = NULL;
  	fabric->tf_cit_tmpl.tfc_tpg_param_cit.ct_attrs = NULL;
  	fabric->tf_cit_tmpl.tfc_tpg_np_base_cit.ct_attrs = NULL;
  	fabric->tf_cit_tmpl.tfc_tpg_nacl_base_cit.ct_attrs = NULL;
  	fabric->tf_cit_tmpl.tfc_tpg_nacl_attrib_cit.ct_attrs = NULL;
  	fabric->tf_cit_tmpl.tfc_tpg_nacl_auth_cit.ct_attrs = NULL;
  	fabric->tf_cit_tmpl.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
  ");
  		return ret;
  	}
  	/*
  	 * Setup our local pointer to *fabric
  	 */
  	tcm_vhost_fabric_configfs = fabric;
  	pr_debug("TCM_VHOST[0] - Set fabric -> tcm_vhost_fabric_configfs
  ");
  	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
  ");
  };
  
  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("VHOST_SCSI series fabric driver");
  MODULE_ALIAS("tcm_vhost");

  MODULE_LICENSE("GPL");
  module_init(tcm_vhost_init);
  module_exit(tcm_vhost_exit);