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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0+
 /*******************************************************************************
  * Vhost kernel TCM fabric driver for virtio SCSI initiators
  *
  * (C) Copyright 2010-2013 Datera, Inc.
  * (C) Copyright 2010-2012 IBM Corp.
  *
  * Authors: Nicholas A. Bellinger <nab@daterainc.com>
  *          Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
  ****************************************************************************/
 
 #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/vmalloc.h>
 #include <linux/miscdevice.h>
 #include <asm/unaligned.h>
 #include <scsi/scsi_common.h>
 #include <scsi/scsi_proto.h>
 #include <target/target_core_base.h>
 #include <target/target_core_fabric.h>
 #include <linux/vhost.h>
 #include <linux/virtio_scsi.h>
 #include <linux/llist.h>
 #include <linux/bitmap.h>
 
 #include "vhost.h"
 
 #define VHOST_SCSI_VERSION  "v0.1"
 #define VHOST_SCSI_NAMELEN 256
 #define VHOST_SCSI_MAX_CDB_SIZE 32
 #define VHOST_SCSI_PREALLOC_SGLS 2048
 #define VHOST_SCSI_PREALLOC_UPAGES 2048
 #define VHOST_SCSI_PREALLOC_PROT_SGLS 2048
 
 /* Max number of requests before requeueing the job.
  * Using this limit prevents one virtqueue from starving others with
  * request.
  */
 #define VHOST_SCSI_WEIGHT 256
 
 struct vhost_scsi_inflight {
     /* Wait for the flush operation to finish */
     struct completion comp;
     /* Refcount for the inflight reqs */
     struct kref kref;
 };
 
 struct vhost_scsi_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 response incoming iovecs */
     int tvc_in_iovs;
     /* 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 vhost_scsi_target_queue_cmd() */
     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 header iovec */
     struct iovec tvc_resp_iov;
     /* 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 vhost_scsi_nexus *tvc_nexus;
     /* The TCM I/O descriptor that is accessed via container_of() */
     struct se_cmd tvc_se_cmd;
     /* Copy of the incoming SCSI command descriptor block (CDB) */
     unsigned char tvc_cdb[VHOST_SCSI_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 vhost_scsi_nexus {
     /* Pointer to TCM session for I_T Nexus */
     struct se_session *tvn_se_sess;
 };
 
 struct vhost_scsi_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;
     /* Used for enabling T10-PI with legacy devices */
     int tv_fabric_prot_type;
     /* list for vhost_scsi_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 vhost_scsi_nexus *tpg_nexus;
     /* Pointer back to vhost_scsi_tport */
     struct vhost_scsi_tport *tport;
     /* Returned by vhost_scsi_make_tpg() */
     struct se_portal_group se_tpg;
     /* Pointer back to vhost_scsi, protected by tv_tpg_mutex */
     struct vhost_scsi *vhost_scsi;
     struct list_head tmf_queue;
 };
 
 struct vhost_scsi_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[VHOST_SCSI_NAMELEN];
     /* Returned by vhost_scsi_make_tport() */
     struct se_wwn tport_wwn;
 };
 
 struct vhost_scsi_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,
 };
 
 /* Note: can't set VIRTIO_F_VERSION_1 yet, since that implies ANY_LAYOUT. */
 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_IO_VQ    1024
 #define VHOST_SCSI_MAX_EVENT    128
 
 static unsigned vhost_scsi_max_io_vqs = 128;
 module_param_named(max_io_vqs, vhost_scsi_max_io_vqs, uint, 0644);
 MODULE_PARM_DESC(max_io_vqs, "Set the max number of IO virtqueues a vhost scsi device can support. The default is 128. The max is 1024.");
 
 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_cmd *scsi_cmds;
     struct sbitmap scsi_tags;
     int max_cmds;
 };
 
 struct vhost_scsi {
     /* Protected by vhost_scsi->dev.mutex */
     struct vhost_scsi_tpg **vs_tpg;
     char vs_vhost_wwpn[TRANSPORT_IQN_LEN];
 
     struct vhost_dev dev;
     struct vhost_scsi_virtqueue *vqs;
     unsigned long *compl_bitmap;
     struct vhost_scsi_inflight **old_inflight;
 
     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 */
 };
 
 struct vhost_scsi_tmf {
     struct vhost_work vwork;
     struct vhost_scsi_tpg *tpg;
     struct vhost_scsi *vhost;
     struct vhost_scsi_virtqueue *svq;
     struct list_head queue_entry;
 
     struct se_cmd se_cmd;
     u8 scsi_resp;
     struct vhost_scsi_inflight *inflight;
     struct iovec resp_iov;
     int in_iovs;
     int vq_desc;
 };
 
 /*
  * Context for processing request and control queue operations.
  */
 struct vhost_scsi_ctx {
     int head;
     unsigned int out, in;
     size_t req_size, rsp_size;
     size_t out_size, in_size;
     u8 *target, *lunp;
     void *req;
     struct iov_iter out_iter;
 };
 
 /* Global spinlock to protect vhost_scsi TPG list for vhost IOCTL access */
 static DEFINE_MUTEX(vhost_scsi_mutex);
 static LIST_HEAD(vhost_scsi_list);
 
 static void vhost_scsi_done_inflight(struct kref *kref)
 {
     struct vhost_scsi_inflight *inflight;
 
     inflight = container_of(kref, struct vhost_scsi_inflight, kref);
     complete(&inflight->comp);
 }
 
 static void vhost_scsi_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 < vs->dev.nvqs;  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 *
 vhost_scsi_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 vhost_scsi_put_inflight(struct vhost_scsi_inflight *inflight)
 {
     kref_put(&inflight->kref, vhost_scsi_done_inflight);
 }
 
 static int vhost_scsi_check_true(struct se_portal_group *se_tpg)
 {
     return 1;
 }
 
 static int vhost_scsi_check_false(struct se_portal_group *se_tpg)
 {
     return 0;
 }
 
 static char *vhost_scsi_get_fabric_wwn(struct se_portal_group *se_tpg)
 {
     struct vhost_scsi_tpg *tpg = container_of(se_tpg,
                 struct vhost_scsi_tpg, se_tpg);
     struct vhost_scsi_tport *tport = tpg->tport;
 
     return &tport->tport_name[0];
 }
 
 static u16 vhost_scsi_get_tpgt(struct se_portal_group *se_tpg)
 {
     struct vhost_scsi_tpg *tpg = container_of(se_tpg,
                 struct vhost_scsi_tpg, se_tpg);
     return tpg->tport_tpgt;
 }
 
 static int vhost_scsi_check_prot_fabric_only(struct se_portal_group *se_tpg)
 {
     struct vhost_scsi_tpg *tpg = container_of(se_tpg,
                 struct vhost_scsi_tpg, se_tpg);
 
     return tpg->tv_fabric_prot_type;
 }
 
 static u32 vhost_scsi_tpg_get_inst_index(struct se_portal_group *se_tpg)
 {
     return 1;
 }
 
 static void vhost_scsi_release_cmd_res(struct se_cmd *se_cmd)
 {
     struct vhost_scsi_cmd *tv_cmd = container_of(se_cmd,
                 struct vhost_scsi_cmd, tvc_se_cmd);
     struct vhost_scsi_virtqueue *svq = container_of(tv_cmd->tvc_vq,
                 struct vhost_scsi_virtqueue, vq);
     struct vhost_scsi_inflight *inflight = tv_cmd->inflight;
     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]));
     }
 
     sbitmap_clear_bit(&svq->scsi_tags, se_cmd->map_tag);
     vhost_scsi_put_inflight(inflight);
 }
 
 static void vhost_scsi_release_tmf_res(struct vhost_scsi_tmf *tmf)
 {
     struct vhost_scsi_tpg *tpg = tmf->tpg;
     struct vhost_scsi_inflight *inflight = tmf->inflight;
 
     mutex_lock(&tpg->tv_tpg_mutex);
     list_add_tail(&tpg->tmf_queue, &tmf->queue_entry);
     mutex_unlock(&tpg->tv_tpg_mutex);
     vhost_scsi_put_inflight(inflight);
 }
 
 static void vhost_scsi_release_cmd(struct se_cmd *se_cmd)
 {
     if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB) {
         struct vhost_scsi_tmf *tmf = container_of(se_cmd,
                     struct vhost_scsi_tmf, se_cmd);
 
         vhost_work_queue(&tmf->vhost->dev, &tmf->vwork);
     } else {
         struct vhost_scsi_cmd *cmd = container_of(se_cmd,
                     struct vhost_scsi_cmd, tvc_se_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 u32 vhost_scsi_sess_get_index(struct se_session *se_sess)
 {
     return 0;
 }
 
 static int vhost_scsi_write_pending(struct se_cmd *se_cmd)
 {
     /* Go ahead and process the write immediately */
     target_execute_cmd(se_cmd);
     return 0;
 }
 
 static void vhost_scsi_set_default_node_attrs(struct se_node_acl *nacl)
 {
     return;
 }
 
 static int vhost_scsi_get_cmd_state(struct se_cmd *se_cmd)
 {
     return 0;
 }
 
 static int vhost_scsi_queue_data_in(struct se_cmd *se_cmd)
 {
     transport_generic_free_cmd(se_cmd, 0);
     return 0;
 }
 
 static int vhost_scsi_queue_status(struct se_cmd *se_cmd)
 {
     transport_generic_free_cmd(se_cmd, 0);
     return 0;
 }
 
 static void vhost_scsi_queue_tm_rsp(struct se_cmd *se_cmd)
 {
     struct vhost_scsi_tmf *tmf = container_of(se_cmd, struct vhost_scsi_tmf,
                           se_cmd);
 
     tmf->scsi_resp = se_cmd->se_tmr_req->response;
     transport_generic_free_cmd(&tmf->se_cmd, 0);
 }
 
 static void vhost_scsi_aborted_task(struct se_cmd *se_cmd)
 {
     return;
 }
 
 static void vhost_scsi_free_evt(struct vhost_scsi *vs, struct vhost_scsi_evt *evt)
 {
     vs->vs_events_nr--;
     kfree(evt);
 }
 
 static struct vhost_scsi_evt *
 vhost_scsi_allocate_evt(struct vhost_scsi *vs,
                u32 event, u32 reason)
 {
     struct vhost_virtqueue *vq = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
     struct vhost_scsi_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 vhost_scsi_evt\n");
         vs->vs_events_missed = true;
         return NULL;
     }
 
     evt->event.event = cpu_to_vhost32(vq, event);
     evt->event.reason = cpu_to_vhost32(vq, reason);
     vs->vs_events_nr++;
 
     return evt;
 }
 
 static int vhost_scsi_check_stop_free(struct se_cmd *se_cmd)
 {
     return target_put_sess_cmd(se_cmd);
 }
 
 static void
 vhost_scsi_do_evt_work(struct vhost_scsi *vs, struct vhost_scsi_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 (!vhost_vq_get_backend(vq)) {
         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\n",
                 vq->iov[out].iov_len);
         vs->vs_events_missed = true;
         return;
     }
 
     if (vs->vs_events_missed) {
         event->event |= cpu_to_vhost32(vq, 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 vhost_scsi_send_event\n");
 }
 
 static void vhost_scsi_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 vhost_scsi_evt *evt, *t;
     struct llist_node *llnode;
 
     mutex_lock(&vq->mutex);
     llnode = llist_del_all(&vs->vs_event_list);
     llist_for_each_entry_safe(evt, t, llnode, list) {
         vhost_scsi_do_evt_work(vs, evt);
         vhost_scsi_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);
     struct virtio_scsi_cmd_resp v_rsp;
     struct vhost_scsi_cmd *cmd, *t;
     struct llist_node *llnode;
     struct se_cmd *se_cmd;
     struct iov_iter iov_iter;
     int ret, vq;
 
     bitmap_zero(vs->compl_bitmap, vs->dev.nvqs);
     llnode = llist_del_all(&vs->vs_completion_list);
     llist_for_each_entry_safe(cmd, t, llnode, tvc_completion_list) {
         se_cmd = &cmd->tvc_se_cmd;
 
         pr_debug("%s tv_cmd %p resid %u status %#02x\n", __func__,
             cmd, se_cmd->residual_count, se_cmd->scsi_status);
 
         memset(&v_rsp, 0, sizeof(v_rsp));
         v_rsp.resid = cpu_to_vhost32(cmd->tvc_vq, se_cmd->residual_count);
         /* TODO is status_qualifier field needed? */
         v_rsp.status = se_cmd->scsi_status;
         v_rsp.sense_len = cpu_to_vhost32(cmd->tvc_vq,
                          se_cmd->scsi_sense_length);
         memcpy(v_rsp.sense, cmd->tvc_sense_buf,
                se_cmd->scsi_sense_length);
 
         iov_iter_init(&iov_iter, READ, &cmd->tvc_resp_iov,
                   cmd->tvc_in_iovs, sizeof(v_rsp));
         ret = copy_to_iter(&v_rsp, sizeof(v_rsp), &iov_iter);
         if (likely(ret == sizeof(v_rsp))) {
             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, vs->compl_bitmap);
         } else
             pr_err("Faulted on virtio_scsi_cmd_resp\n");
 
         vhost_scsi_release_cmd_res(se_cmd);
     }
 
     vq = -1;
     while ((vq = find_next_bit(vs->compl_bitmap, vs->dev.nvqs, vq + 1))
         < vs->dev.nvqs)
         vhost_signal(&vs->dev, &vs->vqs[vq].vq);
 }
 
 static struct vhost_scsi_cmd *
 vhost_scsi_get_cmd(struct vhost_virtqueue *vq, struct vhost_scsi_tpg *tpg,
            unsigned char *cdb, u64 scsi_tag, u16 lun, u8 task_attr,
            u32 exp_data_len, int data_direction)
 {
     struct vhost_scsi_virtqueue *svq = container_of(vq,
                     struct vhost_scsi_virtqueue, vq);
     struct vhost_scsi_cmd *cmd;
     struct vhost_scsi_nexus *tv_nexus;
     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 vhost_scsi_nexus\n");
         return ERR_PTR(-EIO);
     }
 
     tag = sbitmap_get(&svq->scsi_tags);
     if (tag < 0) {
         pr_err("Unable to obtain tag for vhost_scsi_cmd\n");
         return ERR_PTR(-ENOMEM);
     }
 
     cmd = &svq->scsi_cmds[tag];
     sg = cmd->tvc_sgl;
     prot_sg = cmd->tvc_prot_sgl;
     pages = cmd->tvc_upages;
     memset(cmd, 0, sizeof(*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 = vhost_scsi_get_inflight(vq);
 
     memcpy(cmd->tvc_cdb, cdb, VHOST_SCSI_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 vhost_scsi_cmd *cmd,
               struct iov_iter *iter,
               struct scatterlist *sgl,
               bool write)
 {
     struct page **pages = cmd->tvc_upages;
     struct scatterlist *sg = sgl;
     ssize_t bytes;
     size_t offset;
     unsigned int npages = 0;
 
     bytes = iov_iter_get_pages2(iter, pages, LONG_MAX,
                 VHOST_SCSI_PREALLOC_UPAGES, &offset);
     /* No pages were pinned */
     if (bytes <= 0)
         return bytes < 0 ? bytes : -EFAULT;
 
     while (bytes) {
         unsigned n = min_t(unsigned, PAGE_SIZE - offset, bytes);
         sg_set_page(sg++, pages[npages++], n, offset);
         bytes -= n;
         offset = 0;
     }
     return npages;
 }
 
 static int
 vhost_scsi_calc_sgls(struct iov_iter *iter, size_t bytes, int max_sgls)
 {
     int sgl_count = 0;
 
     if (!iter || !iter->iov) {
         pr_err("%s: iter->iov is NULL, but expected bytes: %zu"
                " present\n", __func__, bytes);
         return -EINVAL;
     }
 
     sgl_count = iov_iter_npages(iter, 0xffff);
     if (sgl_count > max_sgls) {
         pr_err("%s: requested sgl_count: %d exceeds pre-allocated"
                " max_sgls: %d\n", __func__, sgl_count, max_sgls);
         return -EINVAL;
     }
     return sgl_count;
 }
 
 static int
 vhost_scsi_iov_to_sgl(struct vhost_scsi_cmd *cmd, bool write,
               struct iov_iter *iter,
               struct scatterlist *sg, int sg_count)
 {
     struct scatterlist *p = sg;
     int ret;
 
     while (iov_iter_count(iter)) {
         ret = vhost_scsi_map_to_sgl(cmd, iter, sg, write);
         if (ret < 0) {
             while (p < sg) {
                 struct page *page = sg_page(p++);
                 if (page)
                     put_page(page);
             }
             return ret;
         }
         sg += ret;
     }
     return 0;
 }
 
 static int
 vhost_scsi_mapal(struct vhost_scsi_cmd *cmd,
          size_t prot_bytes, struct iov_iter *prot_iter,
          size_t data_bytes, struct iov_iter *data_iter)
 {
     int sgl_count, ret;
     bool write = (cmd->tvc_data_direction == DMA_FROM_DEVICE);
 
     if (prot_bytes) {
         sgl_count = vhost_scsi_calc_sgls(prot_iter, prot_bytes,
                          VHOST_SCSI_PREALLOC_PROT_SGLS);
         if (sgl_count < 0)
             return sgl_count;
 
         sg_init_table(cmd->tvc_prot_sgl, sgl_count);
         cmd->tvc_prot_sgl_count = sgl_count;
         pr_debug("%s prot_sg %p prot_sgl_count %u\n", __func__,
              cmd->tvc_prot_sgl, cmd->tvc_prot_sgl_count);
 
         ret = vhost_scsi_iov_to_sgl(cmd, write, prot_iter,
                         cmd->tvc_prot_sgl,
                         cmd->tvc_prot_sgl_count);
         if (ret < 0) {
             cmd->tvc_prot_sgl_count = 0;
             return ret;
         }
     }
     sgl_count = vhost_scsi_calc_sgls(data_iter, data_bytes,
                      VHOST_SCSI_PREALLOC_SGLS);
     if (sgl_count < 0)
         return sgl_count;
 
     sg_init_table(cmd->tvc_sgl, sgl_count);
     cmd->tvc_sgl_count = sgl_count;
     pr_debug("%s data_sg %p data_sgl_count %u\n", __func__,
           cmd->tvc_sgl, cmd->tvc_sgl_count);
 
     ret = vhost_scsi_iov_to_sgl(cmd, write, data_iter,
                     cmd->tvc_sgl, cmd->tvc_sgl_count);
     if (ret < 0) {
         cmd->tvc_sgl_count = 0;
         return ret;
     }
     return 0;
 }
 
 static int vhost_scsi_to_tcm_attr(int attr)
 {
     switch (attr) {
     case VIRTIO_SCSI_S_SIMPLE:
         return TCM_SIMPLE_TAG;
     case VIRTIO_SCSI_S_ORDERED:
         return TCM_ORDERED_TAG;
     case VIRTIO_SCSI_S_HEAD:
         return TCM_HEAD_TAG;
     case VIRTIO_SCSI_S_ACA:
         return TCM_ACA_TAG;
     default:
         break;
     }
     return TCM_SIMPLE_TAG;
 }
 
 static void vhost_scsi_target_queue_cmd(struct vhost_scsi_cmd *cmd)
 {
     struct se_cmd *se_cmd = &cmd->tvc_se_cmd;
     struct vhost_scsi_nexus *tv_nexus;
     struct scatterlist *sg_ptr, *sg_prot_ptr = NULL;
 
     /* 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;
 
     se_cmd->tag = 0;
     target_init_cmd(se_cmd, tv_nexus->tvn_se_sess, &cmd->tvc_sense_buf[0],
             cmd->tvc_lun, cmd->tvc_exp_data_len,
             vhost_scsi_to_tcm_attr(cmd->tvc_task_attr),
             cmd->tvc_data_direction, TARGET_SCF_ACK_KREF);
 
     if (target_submit_prep(se_cmd, cmd->tvc_cdb, sg_ptr,
                    cmd->tvc_sgl_count, NULL, 0, sg_prot_ptr,
                    cmd->tvc_prot_sgl_count, GFP_KERNEL))
         return;
 
     target_queue_submission(se_cmd);
 }
 
 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\n");
 }
 
 static int
 vhost_scsi_get_desc(struct vhost_scsi *vs, struct vhost_virtqueue *vq,
             struct vhost_scsi_ctx *vc)
 {
     int ret = -ENXIO;
 
     vc->head = vhost_get_vq_desc(vq, vq->iov,
                      ARRAY_SIZE(vq->iov), &vc->out, &vc->in,
                      NULL, NULL);
 
     pr_debug("vhost_get_vq_desc: head: %d, out: %u in: %u\n",
          vc->head, vc->out, vc->in);
 
     /* On error, stop handling until the next kick. */
     if (unlikely(vc->head < 0))
         goto done;
 
     /* Nothing new?  Wait for eventfd to tell us they refilled. */
     if (vc->head == vq->num) {
         if (unlikely(vhost_enable_notify(&vs->dev, vq))) {
             vhost_disable_notify(&vs->dev, vq);
             ret = -EAGAIN;
         }
         goto done;
     }
 
     /*
      * Get the size of request and response buffers.
      * FIXME: Not correct for BIDI operation
      */
     vc->out_size = iov_length(vq->iov, vc->out);
     vc->in_size = iov_length(&vq->iov[vc->out], vc->in);
 
     /*
      * Copy over the virtio-scsi request header, which for a
      * ANY_LAYOUT enabled guest may span multiple iovecs, or a
      * single iovec may contain both the header + outgoing
      * WRITE payloads.
      *
      * copy_from_iter() will advance out_iter, so that it will
      * point at the start of the outgoing WRITE payload, if
      * DMA_TO_DEVICE is set.
      */
     iov_iter_init(&vc->out_iter, WRITE, vq->iov, vc->out, vc->out_size);
     ret = 0;
 
 done:
     return ret;
 }
 
 static int
 vhost_scsi_chk_size(struct vhost_virtqueue *vq, struct vhost_scsi_ctx *vc)
 {
     if (unlikely(vc->in_size < vc->rsp_size)) {
         vq_err(vq,
                "Response buf too small, need min %zu bytes got %zu",
                vc->rsp_size, vc->in_size);
         return -EINVAL;
     } else if (unlikely(vc->out_size < vc->req_size)) {
         vq_err(vq,
                "Request buf too small, need min %zu bytes got %zu",
                vc->req_size, vc->out_size);
         return -EIO;
     }
 
     return 0;
 }
 
 static int
 vhost_scsi_get_req(struct vhost_virtqueue *vq, struct vhost_scsi_ctx *vc,
            struct vhost_scsi_tpg **tpgp)
 {
     int ret = -EIO;
 
     if (unlikely(!copy_from_iter_full(vc->req, vc->req_size,
                       &vc->out_iter))) {
         vq_err(vq, "Faulted on copy_from_iter_full\n");
     } else if (unlikely(*vc->lunp != 1)) {
         /* virtio-scsi spec requires byte 0 of the lun to be 1 */
         vq_err(vq, "Illegal virtio-scsi lun: %u\n", *vc->lunp);
     } else {
         struct vhost_scsi_tpg **vs_tpg, *tpg;
 
         vs_tpg = vhost_vq_get_backend(vq);  /* validated at handler entry */
 
         tpg = READ_ONCE(vs_tpg[*vc->target]);
         if (unlikely(!tpg)) {
             vq_err(vq, "Target 0x%x does not exist\n", *vc->target);
         } else {
             if (tpgp)
                 *tpgp = tpg;
             ret = 0;
         }
     }
 
     return ret;
 }
 
 static u16 vhost_buf_to_lun(u8 *lun_buf)
 {
     return ((lun_buf[2] << 8) | lun_buf[3]) & 0x3FFF;
 }
 
 static void
 vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
 {
     struct vhost_scsi_tpg **vs_tpg, *tpg;
     struct virtio_scsi_cmd_req v_req;
     struct virtio_scsi_cmd_req_pi v_req_pi;
     struct vhost_scsi_ctx vc;
     struct vhost_scsi_cmd *cmd;
     struct iov_iter in_iter, prot_iter, data_iter;
     u64 tag;
     u32 exp_data_len, data_direction;
     int ret, prot_bytes, c = 0;
     u16 lun;
     u8 task_attr;
     bool t10_pi = vhost_has_feature(vq, VIRTIO_SCSI_F_T10_PI);
     void *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 = vhost_vq_get_backend(vq);
     if (!vs_tpg)
         goto out;
 
     memset(&vc, 0, sizeof(vc));
     vc.rsp_size = sizeof(struct virtio_scsi_cmd_resp);
 
     vhost_disable_notify(&vs->dev, vq);
 
     do {
         ret = vhost_scsi_get_desc(vs, vq, &vc);
         if (ret)
             goto err;
 
         /*
          * Setup pointers and values based upon different virtio-scsi
          * request header if T10_PI is enabled in KVM guest.
          */
         if (t10_pi) {
             vc.req = &v_req_pi;
             vc.req_size = sizeof(v_req_pi);
             vc.lunp = &v_req_pi.lun[0];
             vc.target = &v_req_pi.lun[1];
         } else {
             vc.req = &v_req;
             vc.req_size = sizeof(v_req);
             vc.lunp = &v_req.lun[0];
             vc.target = &v_req.lun[1];
         }
 
         /*
          * Validate the size of request and response buffers.
          * Check for a sane response buffer so we can report
          * early errors back to the guest.
          */
         ret = vhost_scsi_chk_size(vq, &vc);
         if (ret)
             goto err;
 
         ret = vhost_scsi_get_req(vq, &vc, &tpg);
         if (ret)
             goto err;
 
         ret = -EIO; /* bad target on any error from here on */
 
         /*
          * Determine data_direction by calculating the total outgoing
          * iovec sizes + incoming iovec sizes vs. virtio-scsi request +
          * response headers respectively.
          *
          * For DMA_TO_DEVICE this is out_iter, which is already pointing
          * to the right place.
          *
          * For DMA_FROM_DEVICE, the iovec will be just past the end
          * of the virtio-scsi response header in either the same
          * or immediately following iovec.
          *
          * Any associated T10_PI bytes for the outgoing / incoming
          * payloads are included in calculation of exp_data_len here.
          */
         prot_bytes = 0;
 
         if (vc.out_size > vc.req_size) {
             data_direction = DMA_TO_DEVICE;
             exp_data_len = vc.out_size - vc.req_size;
             data_iter = vc.out_iter;
         } else if (vc.in_size > vc.rsp_size) {
             data_direction = DMA_FROM_DEVICE;
             exp_data_len = vc.in_size - vc.rsp_size;
 
             iov_iter_init(&in_iter, READ, &vq->iov[vc.out], vc.in,
                       vc.rsp_size + exp_data_len);
             iov_iter_advance(&in_iter, vc.rsp_size);
             data_iter = in_iter;
         } else {
             data_direction = DMA_NONE;
             exp_data_len = 0;
         }
         /*
          * If T10_PI header + payload is present, setup prot_iter values
          * and recalculate data_iter for vhost_scsi_mapal() mapping to
          * host scatterlists via get_user_pages_fast().
          */
         if (t10_pi) {
             if (v_req_pi.pi_bytesout) {
                 if (data_direction != DMA_TO_DEVICE) {
                     vq_err(vq, "Received non zero pi_bytesout,"
                         " but wrong data_direction\n");
                     goto err;
                 }
                 prot_bytes = vhost32_to_cpu(vq, v_req_pi.pi_bytesout);
             } else if (v_req_pi.pi_bytesin) {
                 if (data_direction != DMA_FROM_DEVICE) {
                     vq_err(vq, "Received non zero pi_bytesin,"
                         " but wrong data_direction\n");
                     goto err;
                 }
                 prot_bytes = vhost32_to_cpu(vq, v_req_pi.pi_bytesin);
             }
             /*
              * Set prot_iter to data_iter and truncate it to
              * prot_bytes, and advance data_iter past any
              * preceeding prot_bytes that may be present.
              *
              * Also fix up the exp_data_len to reflect only the
              * actual data payload length.
              */
             if (prot_bytes) {
                 exp_data_len -= prot_bytes;
                 prot_iter = data_iter;
                 iov_iter_truncate(&prot_iter, prot_bytes);
                 iov_iter_advance(&data_iter, prot_bytes);
             }
             tag = vhost64_to_cpu(vq, v_req_pi.tag);
             task_attr = v_req_pi.task_attr;
             cdb = &v_req_pi.cdb[0];
             lun = vhost_buf_to_lun(v_req_pi.lun);
         } else {
             tag = vhost64_to_cpu(vq, v_req.tag);
             task_attr = v_req.task_attr;
             cdb = &v_req.cdb[0];
             lun = vhost_buf_to_lun(v_req.lun);
         }
         /*
          * Check that the received CDB size does not exceeded our
          * hardcoded max for vhost-scsi, then get a pre-allocated
          * cmd descriptor for the new virtio-scsi tag.
          *
          * TODO what if cdb was too small for varlen cdb header?
          */
         if (unlikely(scsi_command_size(cdb) > VHOST_SCSI_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(cdb), VHOST_SCSI_MAX_CDB_SIZE);
                 goto err;
         }
         cmd = vhost_scsi_get_cmd(vq, tpg, cdb, tag, lun, task_attr,
                      exp_data_len + prot_bytes,
                      data_direction);
         if (IS_ERR(cmd)) {
             vq_err(vq, "vhost_scsi_get_cmd failed %ld\n",
                    PTR_ERR(cmd));
             goto err;
         }
         cmd->tvc_vhost = vs;
         cmd->tvc_vq = vq;
         cmd->tvc_resp_iov = vq->iov[vc.out];
         cmd->tvc_in_iovs = vc.in;
 
         pr_debug("vhost_scsi got command opcode: %#02x, lun: %d\n",
              cmd->tvc_cdb[0], cmd->tvc_lun);
         pr_debug("cmd: %p exp_data_len: %d, prot_bytes: %d data_direction:"
              " %d\n", cmd, exp_data_len, prot_bytes, data_direction);
 
         if (data_direction != DMA_NONE) {
             if (unlikely(vhost_scsi_mapal(cmd, prot_bytes,
                               &prot_iter, exp_data_len,
                               &data_iter))) {
                 vq_err(vq, "Failed to map iov to sgl\n");
                 vhost_scsi_release_cmd_res(&cmd->tvc_se_cmd);
                 goto err;
             }
         }
         /*
          * Save the descriptor from vhost_get_vq_desc() to be used to
          * complete the virtio-scsi request in TCM callback context via
          * vhost_scsi_queue_data_in() and vhost_scsi_queue_status()
          */
         cmd->tvc_vq_desc = vc.head;
         vhost_scsi_target_queue_cmd(cmd);
         ret = 0;
 err:
         /*
          * ENXIO:  No more requests, or read error, wait for next kick
          * EINVAL: Invalid response buffer, drop the request
          * EIO:    Respond with bad target
          * EAGAIN: Pending request
          */
         if (ret == -ENXIO)
             break;
         else if (ret == -EIO)
             vhost_scsi_send_bad_target(vs, vq, vc.head, vc.out);
     } while (likely(!vhost_exceeds_weight(vq, ++c, 0)));
 out:
     mutex_unlock(&vq->mutex);
 }
 
 static void
 vhost_scsi_send_tmf_resp(struct vhost_scsi *vs, struct vhost_virtqueue *vq,
              int in_iovs, int vq_desc, struct iovec *resp_iov,
              int tmf_resp_code)
 {
     struct virtio_scsi_ctrl_tmf_resp rsp;
     struct iov_iter iov_iter;
     int ret;
 
     pr_debug("%s\n", __func__);
     memset(&rsp, 0, sizeof(rsp));
     rsp.response = tmf_resp_code;
 
     iov_iter_init(&iov_iter, READ, resp_iov, in_iovs, sizeof(rsp));
 
     ret = copy_to_iter(&rsp, sizeof(rsp), &iov_iter);
     if (likely(ret == sizeof(rsp)))
         vhost_add_used_and_signal(&vs->dev, vq, vq_desc, 0);
     else
         pr_err("Faulted on virtio_scsi_ctrl_tmf_resp\n");
 }
 
 static void vhost_scsi_tmf_resp_work(struct vhost_work *work)
 {
     struct vhost_scsi_tmf *tmf = container_of(work, struct vhost_scsi_tmf,
                           vwork);
     int resp_code;
 
     if (tmf->scsi_resp == TMR_FUNCTION_COMPLETE)
         resp_code = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
     else
         resp_code = VIRTIO_SCSI_S_FUNCTION_REJECTED;
 
     vhost_scsi_send_tmf_resp(tmf->vhost, &tmf->svq->vq, tmf->in_iovs,
                  tmf->vq_desc, &tmf->resp_iov, resp_code);
     vhost_scsi_release_tmf_res(tmf);
 }
 
 static void
 vhost_scsi_handle_tmf(struct vhost_scsi *vs, struct vhost_scsi_tpg *tpg,
               struct vhost_virtqueue *vq,
               struct virtio_scsi_ctrl_tmf_req *vtmf,
               struct vhost_scsi_ctx *vc)
 {
     struct vhost_scsi_virtqueue *svq = container_of(vq,
                     struct vhost_scsi_virtqueue, vq);
     struct vhost_scsi_tmf *tmf;
 
     if (vhost32_to_cpu(vq, vtmf->subtype) !=
         VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET)
         goto send_reject;
 
     if (!tpg->tpg_nexus || !tpg->tpg_nexus->tvn_se_sess) {
         pr_err("Unable to locate active struct vhost_scsi_nexus for LUN RESET.\n");
         goto send_reject;
     }
 
     mutex_lock(&tpg->tv_tpg_mutex);
     if (list_empty(&tpg->tmf_queue)) {
         pr_err("Missing reserve TMF. Could not handle LUN RESET.\n");
         mutex_unlock(&tpg->tv_tpg_mutex);
         goto send_reject;
     }
 
     tmf = list_first_entry(&tpg->tmf_queue, struct vhost_scsi_tmf,
                    queue_entry);
     list_del_init(&tmf->queue_entry);
     mutex_unlock(&tpg->tv_tpg_mutex);
 
     tmf->tpg = tpg;
     tmf->vhost = vs;
     tmf->svq = svq;
     tmf->resp_iov = vq->iov[vc->out];
     tmf->vq_desc = vc->head;
     tmf->in_iovs = vc->in;
     tmf->inflight = vhost_scsi_get_inflight(vq);
 
     if (target_submit_tmr(&tmf->se_cmd, tpg->tpg_nexus->tvn_se_sess, NULL,
                   vhost_buf_to_lun(vtmf->lun), NULL,
                   TMR_LUN_RESET, GFP_KERNEL, 0,
                   TARGET_SCF_ACK_KREF) < 0) {
         vhost_scsi_release_tmf_res(tmf);
         goto send_reject;
     }
 
     return;
 
 send_reject:
     vhost_scsi_send_tmf_resp(vs, vq, vc->in, vc->head, &vq->iov[vc->out],
                  VIRTIO_SCSI_S_FUNCTION_REJECTED);
 }
 
 static void
 vhost_scsi_send_an_resp(struct vhost_scsi *vs,
             struct vhost_virtqueue *vq,
             struct vhost_scsi_ctx *vc)
 {
     struct virtio_scsi_ctrl_an_resp rsp;
     struct iov_iter iov_iter;
     int ret;
 
     pr_debug("%s\n", __func__);
     memset(&rsp, 0, sizeof(rsp));   /* event_actual = 0 */
     rsp.response = VIRTIO_SCSI_S_OK;
 
     iov_iter_init(&iov_iter, READ, &vq->iov[vc->out], vc->in, sizeof(rsp));
 
     ret = copy_to_iter(&rsp, sizeof(rsp), &iov_iter);
     if (likely(ret == sizeof(rsp)))
         vhost_add_used_and_signal(&vs->dev, vq, vc->head, 0);
     else
         pr_err("Faulted on virtio_scsi_ctrl_an_resp\n");
 }
 
 static void
 vhost_scsi_ctl_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
 {
     struct vhost_scsi_tpg *tpg;
     union {
         __virtio32 type;
         struct virtio_scsi_ctrl_an_req an;
         struct virtio_scsi_ctrl_tmf_req tmf;
     } v_req;
     struct vhost_scsi_ctx vc;
     size_t typ_size;
     int ret, c = 0;
 
     mutex_lock(&vq->mutex);
     /*
      * We can handle the vq only after the endpoint is setup by calling the
      * VHOST_SCSI_SET_ENDPOINT ioctl.
      */
     if (!vhost_vq_get_backend(vq))
         goto out;
 
     memset(&vc, 0, sizeof(vc));
 
     vhost_disable_notify(&vs->dev, vq);
 
     do {
         ret = vhost_scsi_get_desc(vs, vq, &vc);
         if (ret)
             goto err;
 
         /*
          * Get the request type first in order to setup
          * other parameters dependent on the type.
          */
         vc.req = &v_req.type;
         typ_size = sizeof(v_req.type);
 
         if (unlikely(!copy_from_iter_full(vc.req, typ_size,
                           &vc.out_iter))) {
             vq_err(vq, "Faulted on copy_from_iter tmf type\n");
             /*
              * The size of the response buffer depends on the
              * request type and must be validated against it.
              * Since the request type is not known, don't send
              * a response.
              */
             continue;
         }
 
         switch (vhost32_to_cpu(vq, v_req.type)) {
         case VIRTIO_SCSI_T_TMF:
             vc.req = &v_req.tmf;
             vc.req_size = sizeof(struct virtio_scsi_ctrl_tmf_req);
             vc.rsp_size = sizeof(struct virtio_scsi_ctrl_tmf_resp);
             vc.lunp = &v_req.tmf.lun[0];
             vc.target = &v_req.tmf.lun[1];
             break;
         case VIRTIO_SCSI_T_AN_QUERY:
         case VIRTIO_SCSI_T_AN_SUBSCRIBE:
             vc.req = &v_req.an;
             vc.req_size = sizeof(struct virtio_scsi_ctrl_an_req);
             vc.rsp_size = sizeof(struct virtio_scsi_ctrl_an_resp);
             vc.lunp = &v_req.an.lun[0];
             vc.target = NULL;
             break;
         default:
             vq_err(vq, "Unknown control request %d", v_req.type);
             continue;
         }
 
         /*
          * Validate the size of request and response buffers.
          * Check for a sane response buffer so we can report
          * early errors back to the guest.
          */
         ret = vhost_scsi_chk_size(vq, &vc);
         if (ret)
             goto err;
 
         /*
          * Get the rest of the request now that its size is known.
          */
         vc.req += typ_size;
         vc.req_size -= typ_size;
 
         ret = vhost_scsi_get_req(vq, &vc, &tpg);
         if (ret)
             goto err;
 
         if (v_req.type == VIRTIO_SCSI_T_TMF)
             vhost_scsi_handle_tmf(vs, tpg, vq, &v_req.tmf, &vc);
         else
             vhost_scsi_send_an_resp(vs, vq, &vc);
 err:
         /*
          * ENXIO:  No more requests, or read error, wait for next kick
          * EINVAL: Invalid response buffer, drop the request
          * EIO:    Respond with bad target
          * EAGAIN: Pending request
          */
         if (ret == -ENXIO)
             break;
         else if (ret == -EIO)
             vhost_scsi_send_bad_target(vs, vq, vc.head, vc.out);
     } while (likely(!vhost_exceeds_weight(vq, ++c, 0)));
 out:
     mutex_unlock(&vq->mutex);
 }
 
 static void vhost_scsi_ctl_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);
 
     pr_debug("%s: The handling func for control queue.\n", __func__);
     vhost_scsi_ctl_handle_vq(vs, vq);
 }
 
 static void
 vhost_scsi_send_evt(struct vhost_scsi *vs,
            struct vhost_scsi_tpg *tpg,
            struct se_lun *lun,
            u32 event,
            u32 reason)
 {
     struct vhost_scsi_evt *evt;
 
     evt = vhost_scsi_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;
         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 (!vhost_vq_get_backend(vq))
         goto out;
 
     if (vs->vs_events_missed)
         vhost_scsi_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);
 }
 
 /* Callers must hold dev mutex */
 static void vhost_scsi_flush(struct vhost_scsi *vs)
 {
     int i;
 
     /* Init new inflight and remember the old inflight */
     vhost_scsi_init_inflight(vs, 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 < vs->dev.nvqs; i++)
         kref_put(&vs->old_inflight[i]->kref, vhost_scsi_done_inflight);
 
     /* Flush both the vhost poll and vhost work */
     vhost_dev_flush(&vs->dev);
 
     /* Wait for all reqs issued before the flush to be finished */
     for (i = 0; i < vs->dev.nvqs; i++)
         wait_for_completion(&vs->old_inflight[i]->comp);
 }
 
 static void vhost_scsi_destroy_vq_cmds(struct vhost_virtqueue *vq)
 {
     struct vhost_scsi_virtqueue *svq = container_of(vq,
                     struct vhost_scsi_virtqueue, vq);
     struct vhost_scsi_cmd *tv_cmd;
     unsigned int i;
 
     if (!svq->scsi_cmds)
         return;
 
     for (i = 0; i < svq->max_cmds; i++) {
         tv_cmd = &svq->scsi_cmds[i];
 
         kfree(tv_cmd->tvc_sgl);
         kfree(tv_cmd->tvc_prot_sgl);
         kfree(tv_cmd->tvc_upages);
     }
 
     sbitmap_free(&svq->scsi_tags);
     kfree(svq->scsi_cmds);
     svq->scsi_cmds = NULL;
 }
 
 static int vhost_scsi_setup_vq_cmds(struct vhost_virtqueue *vq, int max_cmds)
 {
     struct vhost_scsi_virtqueue *svq = container_of(vq,
                     struct vhost_scsi_virtqueue, vq);
     struct vhost_scsi_cmd *tv_cmd;
     unsigned int i;
 
     if (svq->scsi_cmds)
         return 0;
 
     if (sbitmap_init_node(&svq->scsi_tags, max_cmds, -1, GFP_KERNEL,
                   NUMA_NO_NODE, false, true))
         return -ENOMEM;
     svq->max_cmds = max_cmds;
 
     svq->scsi_cmds = kcalloc(max_cmds, sizeof(*tv_cmd), GFP_KERNEL);
     if (!svq->scsi_cmds) {
         sbitmap_free(&svq->scsi_tags);
         return -ENOMEM;
     }
 
     for (i = 0; i < max_cmds; i++) {
         tv_cmd = &svq->scsi_cmds[i];
 
         tv_cmd->tvc_sgl = kcalloc(VHOST_SCSI_PREALLOC_SGLS,
                       sizeof(struct scatterlist),
                       GFP_KERNEL);
         if (!tv_cmd->tvc_sgl) {
             pr_err("Unable to allocate tv_cmd->tvc_sgl\n");
             goto out;
         }
 
         tv_cmd->tvc_upages = kcalloc(VHOST_SCSI_PREALLOC_UPAGES,
                          sizeof(struct page *),
                          GFP_KERNEL);
         if (!tv_cmd->tvc_upages) {
             pr_err("Unable to allocate tv_cmd->tvc_upages\n");
             goto out;
         }
 
         tv_cmd->tvc_prot_sgl = kcalloc(VHOST_SCSI_PREALLOC_PROT_SGLS,
                            sizeof(struct scatterlist),
                            GFP_KERNEL);
         if (!tv_cmd->tvc_prot_sgl) {
             pr_err("Unable to allocate tv_cmd->tvc_prot_sgl\n");
             goto out;
         }
     }
     return 0;
 out:
     vhost_scsi_destroy_vq_cmds(vq);
     return -ENOMEM;
 }
 
 /*
  * Called from vhost_scsi_ioctl() context to walk the list of available
  * vhost_scsi_tpg with an active struct vhost_scsi_nexus
  *
  *  The lock nesting rule is:
  *    vhost_scsi_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 se_portal_group *se_tpg;
     struct vhost_scsi_tport *tv_tport;
     struct vhost_scsi_tpg *tpg;
     struct vhost_scsi_tpg **vs_tpg;
     struct vhost_virtqueue *vq;
     int index, ret, i, len;
     bool match = false;
 
     mutex_lock(&vhost_scsi_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, &vhost_scsi_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]) {
                 mutex_unlock(&tpg->tv_tpg_mutex);
                 ret = -EEXIST;
                 goto undepend;
             }
             /*
              * In order to ensure individual vhost-scsi configfs
              * groups cannot be removed while in use by vhost ioctl,
              * go ahead and take an explicit se_tpg->tpg_group.cg_item
              * dependency now.
              */
             se_tpg = &tpg->se_tpg;
             ret = target_depend_item(&se_tpg->tpg_group.cg_item);
             if (ret) {
                 pr_warn("target_depend_item() failed: %d\n", ret);
                 mutex_unlock(&tpg->tv_tpg_mutex);
                 goto undepend;
             }
             tpg->tv_tpg_vhost_count++;
             tpg->vhost_scsi = vs;
             vs_tpg[tpg->tport_tpgt] = tpg;
             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 = VHOST_SCSI_VQ_IO; i < vs->dev.nvqs; i++) {
             vq = &vs->vqs[i].vq;
             if (!vhost_vq_is_setup(vq))
                 continue;
 
             ret = vhost_scsi_setup_vq_cmds(vq, vq->num);
             if (ret)
                 goto destroy_vq_cmds;
         }
 
         for (i = 0; i < vs->dev.nvqs; i++) {
             vq = &vs->vqs[i].vq;
             mutex_lock(&vq->mutex);
             vhost_vq_set_backend(vq, vs_tpg);
             vhost_vq_init_access(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;
     goto out;
 
 destroy_vq_cmds:
     for (i--; i >= VHOST_SCSI_VQ_IO; i--) {
         if (!vhost_vq_get_backend(&vs->vqs[i].vq))
             vhost_scsi_destroy_vq_cmds(&vs->vqs[i].vq);
     }
 undepend:
     for (i = 0; i < VHOST_SCSI_MAX_TARGET; i++) {
         tpg = vs_tpg[i];
         if (tpg) {
             tpg->tv_tpg_vhost_count--;
             target_undepend_item(&tpg->se_tpg.tpg_group.cg_item);
         }
     }
     kfree(vs_tpg);
 out:
     mutex_unlock(&vs->dev.mutex);
     mutex_unlock(&vhost_scsi_mutex);
     return ret;
 }
 
 static int
 vhost_scsi_clear_endpoint(struct vhost_scsi *vs,
               struct vhost_scsi_target *t)
 {
     struct se_portal_group *se_tpg;
     struct vhost_scsi_tport *tv_tport;
     struct vhost_scsi_tpg *tpg;
     struct vhost_virtqueue *vq;
     bool match = false;
     int index, ret, i;
     u8 target;
 
     mutex_lock(&vhost_scsi_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\n",
                 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);
         /*
          * Release se_tpg->tpg_group.cg_item configfs dependency now
          * to allow vhost-scsi WWPN se_tpg->tpg_group shutdown to occur.
          */
         se_tpg = &tpg->se_tpg;
         target_undepend_item(&se_tpg->tpg_group.cg_item);
     }
     if (match) {
         for (i = 0; i < vs->dev.nvqs; i++) {
             vq = &vs->vqs[i].vq;
             mutex_lock(&vq->mutex);
             vhost_vq_set_backend(vq, NULL);
             mutex_unlock(&vq->mutex);
         }
         /* Make sure cmds are not running before tearing them down. */
         vhost_scsi_flush(vs);
 
         for (i = 0; i < vs->dev.nvqs; i++) {
             vq = &vs->vqs[i].vq;
             vhost_scsi_destroy_vq_cmds(vq);
         }
     }
     /*
      * 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(&vhost_scsi_mutex);
     return 0;
 
 err_tpg:
     mutex_unlock(&tpg->tv_tpg_mutex);
 err_dev:
     mutex_unlock(&vs->dev.mutex);
     mutex_unlock(&vhost_scsi_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 < vs->dev.nvqs; 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, nvqs = vhost_scsi_max_io_vqs;
 
     vs = kvzalloc(sizeof(*vs), GFP_KERNEL);
     if (!vs)
         goto err_vs;
 
     if (nvqs > VHOST_SCSI_MAX_IO_VQ) {
         pr_err("Invalid max_io_vqs of %d. Using %d.\n", nvqs,
                VHOST_SCSI_MAX_IO_VQ);
         nvqs = VHOST_SCSI_MAX_IO_VQ;
     } else if (nvqs == 0) {
         pr_err("Invalid max_io_vqs of %d. Using 1.\n", nvqs);
         nvqs = 1;
     }
     nvqs += VHOST_SCSI_VQ_IO;
 
     vs->compl_bitmap = bitmap_alloc(nvqs, GFP_KERNEL);
     if (!vs->compl_bitmap)
         goto err_compl_bitmap;
 
     vs->old_inflight = kmalloc_array(nvqs, sizeof(*vs->old_inflight),
                      GFP_KERNEL | __GFP_ZERO);
     if (!vs->old_inflight)
         goto err_inflight;
 
     vs->vqs = kmalloc_array(nvqs, sizeof(*vs->vqs),
                 GFP_KERNEL | __GFP_ZERO);
     if (!vs->vqs)
         goto err_vqs;
 
     vqs = kmalloc_array(nvqs, sizeof(*vqs), GFP_KERNEL);
     if (!vqs)
         goto err_local_vqs;
 
     vhost_work_init(&vs->vs_completion_work, vhost_scsi_complete_cmd_work);
     vhost_work_init(&vs->vs_event_work, vhost_scsi_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 < nvqs; i++) {
         vqs[i] = &vs->vqs[i].vq;
         vs->vqs[i].vq.handle_kick = vhost_scsi_handle_kick;
     }
     vhost_dev_init(&vs->dev, vqs, nvqs, UIO_MAXIOV,
                VHOST_SCSI_WEIGHT, 0, true, NULL);
 
     vhost_scsi_init_inflight(vs, NULL);
 
     f->private_data = vs;
     return 0;
 
 err_local_vqs:
     kfree(vs->vqs);
 err_vqs:
     kfree(vs->old_inflight);
 err_inflight:
     bitmap_free(vs->compl_bitmap);
 err_compl_bitmap:
     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);
     kfree(vs->dev.vqs);
     kfree(vs->vqs);
     kfree(vs->old_inflight);
     bitmap_free(vs->compl_bitmap);
     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;
     }
 }
 
 static const struct file_operations vhost_scsi_fops = {
     .owner          = THIS_MODULE,
     .release        = vhost_scsi_release,
     .unlocked_ioctl = vhost_scsi_ioctl,
     .compat_ioctl   = compat_ptr_ioctl,
     .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 void vhost_scsi_deregister(void)
 {
     misc_deregister(&vhost_scsi_misc);
 }
 
 static char *vhost_scsi_dump_proto_id(struct vhost_scsi_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
 vhost_scsi_do_plug(struct vhost_scsi_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))
         vhost_scsi_send_evt(vs, tpg, lun,
                    VIRTIO_SCSI_T_TRANSPORT_RESET, reason);
     mutex_unlock(&vq->mutex);
     mutex_unlock(&vs->dev.mutex);
 }
 
 static void vhost_scsi_hotplug(struct vhost_scsi_tpg *tpg, struct se_lun *lun)
 {
     vhost_scsi_do_plug(tpg, lun, true);
 }
 
 static void vhost_scsi_hotunplug(struct vhost_scsi_tpg *tpg, struct se_lun *lun)
 {
     vhost_scsi_do_plug(tpg, lun, false);
 }
 
 static int vhost_scsi_port_link(struct se_portal_group *se_tpg,
                    struct se_lun *lun)
 {
     struct vhost_scsi_tpg *tpg = container_of(se_tpg,
                 struct vhost_scsi_tpg, se_tpg);
     struct vhost_scsi_tmf *tmf;
 
     tmf = kzalloc(sizeof(*tmf), GFP_KERNEL);
     if (!tmf)
         return -ENOMEM;
     INIT_LIST_HEAD(&tmf->queue_entry);
     vhost_work_init(&tmf->vwork, vhost_scsi_tmf_resp_work);
 
     mutex_lock(&vhost_scsi_mutex);
 
     mutex_lock(&tpg->tv_tpg_mutex);
     tpg->tv_tpg_port_count++;
     list_add_tail(&tmf->queue_entry, &tpg->tmf_queue);
     mutex_unlock(&tpg->tv_tpg_mutex);
 
     vhost_scsi_hotplug(tpg, lun);
 
     mutex_unlock(&vhost_scsi_mutex);
 
     return 0;
 }
 
 static void vhost_scsi_port_unlink(struct se_portal_group *se_tpg,
                   struct se_lun *lun)
 {
     struct vhost_scsi_tpg *tpg = container_of(se_tpg,
                 struct vhost_scsi_tpg, se_tpg);
     struct vhost_scsi_tmf *tmf;
 
     mutex_lock(&vhost_scsi_mutex);
 
     mutex_lock(&tpg->tv_tpg_mutex);
     tpg->tv_tpg_port_count--;
     tmf = list_first_entry(&tpg->tmf_queue, struct vhost_scsi_tmf,
                    queue_entry);
     list_del(&tmf->queue_entry);
     kfree(tmf);
     mutex_unlock(&tpg->tv_tpg_mutex);
 
     vhost_scsi_hotunplug(tpg, lun);
 
     mutex_unlock(&vhost_scsi_mutex);
 }
 
 static ssize_t vhost_scsi_tpg_attrib_fabric_prot_type_store(
         struct config_item *item, const char *page, size_t count)
 {
     struct se_portal_group *se_tpg = attrib_to_tpg(item);
     struct vhost_scsi_tpg *tpg = container_of(se_tpg,
                 struct vhost_scsi_tpg, se_tpg);
     unsigned long val;
     int ret = kstrtoul(page, 0, &val);
 
     if (ret) {
         pr_err("kstrtoul() returned %d for fabric_prot_type\n", ret);
         return ret;
     }
     if (val != 0 && val != 1 && val != 3) {
         pr_err("Invalid vhost_scsi fabric_prot_type: %lu\n", val);
         return -EINVAL;
     }
     tpg->tv_fabric_prot_type = val;
 
     return count;
 }
 
 static ssize_t vhost_scsi_tpg_attrib_fabric_prot_type_show(
         struct config_item *item, char *page)
 {
     struct se_portal_group *se_tpg = attrib_to_tpg(item);
     struct vhost_scsi_tpg *tpg = container_of(se_tpg,
                 struct vhost_scsi_tpg, se_tpg);
 
     return sprintf(page, "%d\n", tpg->tv_fabric_prot_type);
 }
 
 CONFIGFS_ATTR(vhost_scsi_tpg_attrib_, fabric_prot_type);
 
 static struct configfs_attribute *vhost_scsi_tpg_attrib_attrs[] = {
     &vhost_scsi_tpg_attrib_attr_fabric_prot_type,
     NULL,
 };
 
 static int vhost_scsi_make_nexus(struct vhost_scsi_tpg *tpg,
                 const char *name)
 {
     struct vhost_scsi_nexus *tv_nexus;
 
     mutex_lock(&tpg->tv_tpg_mutex);
     if (tpg->tpg_nexus) {
         mutex_unlock(&tpg->tv_tpg_mutex);
         pr_debug("tpg->tpg_nexus already exists\n");
         return -EEXIST;
     }
 
     tv_nexus = kzalloc(sizeof(*tv_nexus), GFP_KERNEL);
     if (!tv_nexus) {
         mutex_unlock(&tpg->tv_tpg_mutex);
         pr_err("Unable to allocate struct vhost_scsi_nexus\n");
         return -ENOMEM;
     }
     /*
      * Since we are running in 'demo mode' this call with generate a
      * struct se_node_acl for the vhost_scsi struct se_portal_group with
      * the SCSI Initiator port name of the passed configfs group 'name'.
      */
     tv_nexus->tvn_se_sess = target_setup_session(&tpg->se_tpg, 0, 0,
                     TARGET_PROT_DIN_PASS | TARGET_PROT_DOUT_PASS,
                     (unsigned char *)name, tv_nexus, NULL);
     if (IS_ERR(tv_nexus->tvn_se_sess)) {
         mutex_unlock(&tpg->tv_tpg_mutex);
         kfree(tv_nexus);
         return -ENOMEM;
     }
     tpg->tpg_nexus = tv_nexus;
 
     mutex_unlock(&tpg->tv_tpg_mutex);
     return 0;
 }
 
 static int vhost_scsi_drop_nexus(struct vhost_scsi_tpg *tpg)
 {
     struct se_session *se_sess;
     struct vhost_scsi_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", vhost_scsi_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
      */
     target_remove_session(se_sess);
     tpg->tpg_nexus = NULL;
     mutex_unlock(&tpg->tv_tpg_mutex);
 
     kfree(tv_nexus);
     return 0;
 }
 
 static ssize_t vhost_scsi_tpg_nexus_show(struct config_item *item, char *page)
 {
     struct se_portal_group *se_tpg = to_tpg(item);
     struct vhost_scsi_tpg *tpg = container_of(se_tpg,
                 struct vhost_scsi_tpg, se_tpg);
     struct vhost_scsi_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\n",
             tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
     mutex_unlock(&tpg->tv_tpg_mutex);
 
     return ret;
 }
 
 static ssize_t vhost_scsi_tpg_nexus_store(struct config_item *item,
         const char *page, size_t count)
 {
     struct se_portal_group *se_tpg = to_tpg(item);
     struct vhost_scsi_tpg *tpg = container_of(se_tpg,
                 struct vhost_scsi_tpg, se_tpg);
     struct vhost_scsi_tport *tport_wwn = tpg->tport;
     unsigned char i_port[VHOST_SCSI_NAMELEN], *ptr, *port_ptr;
     int ret;
     /*
      * Shutdown the active I_T nexus if 'NULL' is passed..
      */
     if (!strncmp(page, "NULL", 4)) {
         ret = vhost_scsi_drop_nexus(tpg);
         return (!ret) ? count : ret;
     }
     /*
      * Otherwise make sure the passed virtual Initiator port WWN matches
      * the fabric protocol_id set in vhost_scsi_make_tport(), and call
      * vhost_scsi_make_nexus().
      */
     if (strlen(page) >= VHOST_SCSI_NAMELEN) {
         pr_err("Emulated NAA Sas Address: %s, exceeds"
                 " max: %d\n", page, VHOST_SCSI_NAMELEN);
         return -EINVAL;
     }
     snprintf(&i_port[0], VHOST_SCSI_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,
                 vhost_scsi_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,
                 vhost_scsi_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,
                 vhost_scsi_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 = vhost_scsi_make_nexus(tpg, port_ptr);
     if (ret < 0)
         return ret;
 
     return count;
 }
 
 CONFIGFS_ATTR(vhost_scsi_tpg_, nexus);
 
 static struct configfs_attribute *vhost_scsi_tpg_attrs[] = {
     &vhost_scsi_tpg_attr_nexus,
     NULL,
 };
 
 static struct se_portal_group *
 vhost_scsi_make_tpg(struct se_wwn *wwn, const char *name)
 {
     struct vhost_scsi_tport *tport = container_of(wwn,
             struct vhost_scsi_tport, tport_wwn);
 
     struct vhost_scsi_tpg *tpg;
     u16 tpgt;
     int ret;
 
     if (strstr(name, "tpgt_") != name)
         return ERR_PTR(-EINVAL);
     if (kstrtou16(name + 5, 10, &tpgt) || tpgt >= VHOST_SCSI_MAX_TARGET)
         return ERR_PTR(-EINVAL);
 
     tpg = kzalloc(sizeof(*tpg), GFP_KERNEL);
     if (!tpg) {
         pr_err("Unable to allocate struct vhost_scsi_tpg");
         return ERR_PTR(-ENOMEM);
     }
     mutex_init(&tpg->tv_tpg_mutex);
     INIT_LIST_HEAD(&tpg->tv_tpg_list);
     INIT_LIST_HEAD(&tpg->tmf_queue);
     tpg->tport = tport;
     tpg->tport_tpgt = tpgt;
 
     ret = core_tpg_register(wwn, &tpg->se_tpg, tport->tport_proto_id);
     if (ret < 0) {
         kfree(tpg);
         return NULL;
     }
     mutex_lock(&vhost_scsi_mutex);
     list_add_tail(&tpg->tv_tpg_list, &vhost_scsi_list);
     mutex_unlock(&vhost_scsi_mutex);
 
     return &tpg->se_tpg;
 }
 
 static void vhost_scsi_drop_tpg(struct se_portal_group *se_tpg)
 {
     struct vhost_scsi_tpg *tpg = container_of(se_tpg,
                 struct vhost_scsi_tpg, se_tpg);
 
     mutex_lock(&vhost_scsi_mutex);
     list_del(&tpg->tv_tpg_list);
     mutex_unlock(&vhost_scsi_mutex);
     /*
      * Release the virtual I_T Nexus for this vhost TPG
      */
     vhost_scsi_drop_nexus(tpg);
     /*
      * Deregister the se_tpg from TCM..
      */
     core_tpg_deregister(se_tpg);
     kfree(tpg);
 }
 
 static struct se_wwn *
 vhost_scsi_make_tport(struct target_fabric_configfs *tf,
              struct config_group *group,
              const char *name)
 {
     struct vhost_scsi_tport *tport;
     char *ptr;
     u64 wwpn = 0;
     int off = 0;
 
     /* if (vhost_scsi_parse_wwn(name, &wwpn, 1) < 0)
         return ERR_PTR(-EINVAL); */
 
     tport = kzalloc(sizeof(*tport), GFP_KERNEL);
     if (!tport) {
         pr_err("Unable to allocate struct vhost_scsi_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) >= VHOST_SCSI_NAMELEN) {
         pr_err("Emulated %s Address: %s, exceeds"
             " max: %d\n", name, vhost_scsi_dump_proto_id(tport),
             VHOST_SCSI_NAMELEN);
         kfree(tport);
         return ERR_PTR(-EINVAL);
     }
     snprintf(&tport->tport_name[0], VHOST_SCSI_NAMELEN, "%s", &name[off]);
 
     pr_debug("TCM_VHost_ConfigFS: Allocated emulated Target"
         " %s Address: %s\n", vhost_scsi_dump_proto_id(tport), name);
 
     return &tport->tport_wwn;
 }
 
 static void vhost_scsi_drop_tport(struct se_wwn *wwn)
 {
     struct vhost_scsi_tport *tport = container_of(wwn,
                 struct vhost_scsi_tport, tport_wwn);
 
     pr_debug("TCM_VHost_ConfigFS: Deallocating emulated Target"
         " %s Address: %s\n", vhost_scsi_dump_proto_id(tport),
         tport->tport_name);
 
     kfree(tport);
 }
 
 static ssize_t
 vhost_scsi_wwn_version_show(struct config_item *item, char *page)
 {
     return sprintf(page, "TCM_VHOST fabric module %s on %s/%s"
         "on "UTS_RELEASE"\n", VHOST_SCSI_VERSION, utsname()->sysname,
         utsname()->machine);
 }
 
 CONFIGFS_ATTR_RO(vhost_scsi_wwn_, version);
 
 static struct configfs_attribute *vhost_scsi_wwn_attrs[] = {
     &vhost_scsi_wwn_attr_version,
     NULL,
 };
 
 static const struct target_core_fabric_ops vhost_scsi_ops = {
     .module             = THIS_MODULE,
     .fabric_name            = "vhost",
     .max_data_sg_nents      = VHOST_SCSI_PREALLOC_SGLS,
     .tpg_get_wwn            = vhost_scsi_get_fabric_wwn,
     .tpg_get_tag            = vhost_scsi_get_tpgt,
     .tpg_check_demo_mode        = vhost_scsi_check_true,
     .tpg_check_demo_mode_cache  = vhost_scsi_check_true,
     .tpg_check_demo_mode_write_protect = vhost_scsi_check_false,
     .tpg_check_prod_mode_write_protect = vhost_scsi_check_false,
     .tpg_check_prot_fabric_only = vhost_scsi_check_prot_fabric_only,
     .tpg_get_inst_index     = vhost_scsi_tpg_get_inst_index,
     .release_cmd            = vhost_scsi_release_cmd,
     .check_stop_free        = vhost_scsi_check_stop_free,
     .sess_get_index         = vhost_scsi_sess_get_index,
     .sess_get_initiator_sid     = NULL,
     .write_pending          = vhost_scsi_write_pending,
     .set_default_node_attributes    = vhost_scsi_set_default_node_attrs,
     .get_cmd_state          = vhost_scsi_get_cmd_state,
     .queue_data_in          = vhost_scsi_queue_data_in,
     .queue_status           = vhost_scsi_queue_status,
     .queue_tm_rsp           = vhost_scsi_queue_tm_rsp,
     .aborted_task           = vhost_scsi_aborted_task,
     /*
      * Setup callers for generic logic in target_core_fabric_configfs.c
      */
     .fabric_make_wwn        = vhost_scsi_make_tport,
     .fabric_drop_wwn        = vhost_scsi_drop_tport,
     .fabric_make_tpg        = vhost_scsi_make_tpg,
     .fabric_drop_tpg        = vhost_scsi_drop_tpg,
     .fabric_post_link       = vhost_scsi_port_link,
     .fabric_pre_unlink      = vhost_scsi_port_unlink,
 
     .tfc_wwn_attrs          = vhost_scsi_wwn_attrs,
     .tfc_tpg_base_attrs     = vhost_scsi_tpg_attrs,
     .tfc_tpg_attrib_attrs       = vhost_scsi_tpg_attrib_attrs,
 };
 
 static int __init vhost_scsi_init(void)
 {
     int ret = -ENOMEM;
 
     pr_debug("TCM_VHOST fabric module %s on %s/%s"
         " on "UTS_RELEASE"\n", VHOST_SCSI_VERSION, utsname()->sysname,
         utsname()->machine);
 
     ret = vhost_scsi_register();
     if (ret < 0)
         goto out;
 
     ret = target_register_template(&vhost_scsi_ops);
     if (ret < 0)
         goto out_vhost_scsi_deregister;
 
     return 0;
 
 out_vhost_scsi_deregister:
     vhost_scsi_deregister();
 out:
     return ret;
 };
 
 static void vhost_scsi_exit(void)
 {
     target_unregister_template(&vhost_scsi_ops);
     vhost_scsi_deregister();
 };
 
 MODULE_DESCRIPTION("VHOST_SCSI series fabric driver");
 MODULE_ALIAS("tcm_vhost");
 MODULE_LICENSE("GPL");
 module_init(vhost_scsi_init);
 module_exit(vhost_scsi_exit);