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[Xen-devel] [PATCH V2 3/4] Introduce XEN scsiback module



From: Juergen Gross <jgross@xxxxxxxx>

Introduces the XEN pvSCSI backend. With pvSCSI it is possible for a XEN domU
to issue SCSI commands to a SCSI LUN assigned to that domU. The SCSI commands
are passed to the pvSCSI backend in a driver domain (usually Dom0) which is
owner of the physical device. This allows e.g. to use SCSI tape drives in a
XEN domU.

The code is taken from the pvSCSI implementation in XEN done by Fujitsu based
on Linux kernel 2.6.18.

Changes from the original version are:
- port to upstream kernel
- put all code in just one source file
- adapt to Linux style guide
- use target core infrastructure instead doing pure pass-through
- enable module unloading
- support SG-list in grant page(s)
- support task abort
- remove redundant struct backend
- allocate resources dynamically
- correct minor error in scsiback_fast_flush_area
- free allocated resources in case of error during I/O preparation
- initialize SCSI emulation table statically
- fix emulation of "report LUNs" to not needing retry

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 drivers/xen/Kconfig        |    9 +
 drivers/xen/Makefile       |    1 +
 drivers/xen/xen-scsiback.c | 2655 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 2665 insertions(+)
 create mode 100644 drivers/xen/xen-scsiback.c

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 38fb36e..fc8f420 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -172,6 +172,15 @@ config XEN_PCIDEV_BACKEND
 
          If in doubt, say m.
 
+config XEN_SCSI_BACKEND
+       tristate "XEN SCSI backend driver"
+       depends on SCSI && XEN && XEN_BACKEND && TARGET_CORE
+       help
+         The SCSI backend driver allows the kernel to export its SCSI Devices
+         to other guests via a high-performance shared-memory interface.
+         Only needed for systems running as XEN driver domains (e.g. Dom0) and
+         if guests need generic access to SCSI devices.
+
 config XEN_PRIVCMD
        tristate
        depends on XEN
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 45e00af..b42ee75 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -33,6 +33,7 @@ obj-$(CONFIG_XEN_STUB)                        += xen-stub.o
 obj-$(CONFIG_XEN_ACPI_HOTPLUG_MEMORY)  += xen-acpi-memhotplug.o
 obj-$(CONFIG_XEN_ACPI_HOTPLUG_CPU)     += xen-acpi-cpuhotplug.o
 obj-$(CONFIG_XEN_ACPI_PROCESSOR)       += xen-acpi-processor.o
+obj-$(CONFIG_XEN_SCSI_BACKEND)         += xen-scsiback.o
 xen-evtchn-y                           := evtchn.o
 xen-gntdev-y                           := gntdev.o
 xen-gntalloc-y                         := gntalloc.o
diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
new file mode 100644
index 0000000..6eed255
--- /dev/null
+++ b/drivers/xen/xen-scsiback.c
@@ -0,0 +1,2655 @@
+/*
+ * Xen SCSI backend driver
+ *
+ * Copyright (c) 2008, FUJITSU Limited
+ *
+ * Based on the blkback driver code.
+ * Adaption to kernel taget core infrastructure taken from vhost/scsi.c
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/*
+ * Patched to support >2TB drives + allow tape & autoloader operations
+ * 2010, Samuel Kvasnica, IMS Nanofabrication AG
+ */
+
+#include <stdarg.h>
+
+#include <linux/module.h>
+#include <linux/utsname.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/wait.h>
+#include <linux/sched.h>
+#include <linux/blkdev.h>
+#include <linux/list.h>
+#include <linux/gfp.h>
+#include <linux/kthread.h>
+#include <linux/delay.h>
+#include <linux/vmalloc.h>
+#include <linux/spinlock.h>
+#include <linux/configfs.h>
+
+#include <generated/utsrelease.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_tcq.h>
+#include <scsi/osd_sense.h>
+
+#include <target/target_core_base.h>
+#include <target/target_core_fabric.h>
+#include <target/target_core_configfs.h>
+#include <target/target_core_fabric_configfs.h>
+
+#include <asm/hypervisor.h>
+
+#include <xen/xen.h>
+#include <xen/balloon.h>
+#include <xen/events.h>
+#include <xen/xenbus.h>
+#include <xen/grant_table.h>
+#include <xen/page.h>
+
+#include <xen/interface/grant_table.h>
+#include <xen/interface/io/vscsiif.h>
+
+#define DPRINTK(_f, _a...)                     \
+       pr_debug("(file=%s, line=%d) " _f, __FILE__ , __LINE__ , ## _a)
+
+#define VSCSI_VERSION  "v0.1"
+#define VSCSI_NAMELEN  32
+
+struct ids_tuple {
+       unsigned int hst;               /* host    */
+       unsigned int chn;               /* channel */
+       unsigned int tgt;               /* target  */
+       unsigned int lun;               /* LUN     */
+};
+
+struct v2p_entry {
+       struct ids_tuple v;             /* translate from */
+       struct scsiback_tpg *tpg;       /* translate to   */
+       unsigned int lun;
+       struct kref kref;
+       struct list_head l;
+};
+
+struct vscsibk_info {
+       struct xenbus_device *dev;
+
+       domid_t domid;
+       unsigned int evtchn;
+       unsigned int irq;
+
+       int feature;
+
+       struct vscsiif_back_ring  ring;
+
+       spinlock_t ring_lock;
+       atomic_t nr_unreplied_reqs;
+
+       spinlock_t v2p_lock;
+       struct list_head v2p_entry_lists;
+
+       struct task_struct *kthread;
+       wait_queue_head_t waiting_to_free;
+       wait_queue_head_t wq;
+       wait_queue_head_t shutdown_wq;
+       unsigned int waiting_reqs;
+};
+
+/* theoretical maximum of grants for one request */
+#define VSCSI_MAX_GRANTS       (SG_ALL + VSCSIIF_SG_TABLESIZE)
+
+/*
+ * VSCSI_GRANT_BATCH is the maximum number of grants to be processed in one
+ * call to map/unmap grants. Don't choose it too large, as there are arrays
+ * with VSCSI_GRANT_BATCH elements allocated on the stack.
+ */
+#define VSCSI_GRANT_BATCH      16
+
+struct vscsibk_pend {
+       uint16_t rqid;
+
+       uint8_t cmnd[VSCSIIF_MAX_COMMAND_SIZE];
+       uint8_t cmd_len;
+
+       uint8_t sc_data_direction;
+       uint16_t n_sg;          /* real length of SG list */
+       uint16_t n_grants;      /* SG pages and potentially SG list */
+       uint32_t data_len;
+       uint32_t result;
+
+       struct vscsibk_info *info;
+       struct v2p_entry *v2p;
+       struct scatterlist *sgl;
+
+       uint8_t sense_buffer[VSCSIIF_SENSE_BUFFERSIZE];
+
+       grant_handle_t grant_handles[VSCSI_MAX_GRANTS];
+       struct page *pages[VSCSI_MAX_GRANTS];
+
+       struct se_cmd se_cmd;
+};
+
+struct scsiback_tmr {
+       atomic_t tmr_complete;
+       wait_queue_head_t tmr_wait;
+};
+
+struct vscsibk_emulate {
+       void (*pre_function)(struct vscsibk_pend *, void *);
+       void (*post_function)(struct vscsibk_pend *, void *);
+};
+
+struct scsiback_nexus {
+       /* Pointer to TCM session for I_T Nexus */
+       struct se_session *tvn_se_sess;
+};
+
+struct scsiback_nacl {
+       /* Binary World Wide unique Port Name for pvscsi Initiator port */
+       u64 iport_wwpn;
+       /* ASCII formatted WWPN for Sas Initiator port */
+       char iport_name[VSCSI_NAMELEN];
+       /* Returned by scsiback_make_nodeacl() */
+       struct se_node_acl se_node_acl;
+};
+
+struct scsiback_tport {
+       /* SCSI protocol the tport is providing */
+       u8 tport_proto_id;
+       /* Binary World Wide unique Port Name for pvscsi Target port */
+       u64 tport_wwpn;
+       /* ASCII formatted WWPN for pvscsi Target port */
+       char tport_name[VSCSI_NAMELEN];
+       /* Returned by scsiback_make_tport() */
+       struct se_wwn tport_wwn;
+};
+
+struct scsiback_tpg {
+       /* scsiback port target portal group tag for TCM */
+       u16 tport_tpgt;
+       /* track number of TPG Port/Lun Links wrt explicit I_T Nexus shutdown */
+       int tv_tpg_port_count;
+       /* xen-pvscsi references to tpg_nexus, protected by tv_tpg_mutex */
+       int tv_tpg_fe_count;
+       /* list for scsiback_list */
+       struct list_head tv_tpg_list;
+       /* Used to protect access for tpg_nexus */
+       struct mutex tv_tpg_mutex;
+       /* Pointer to the TCM pvscsi I_T Nexus for this TPG endpoint */
+       struct scsiback_nexus *tpg_nexus;
+       /* Pointer back to scsiback_tport */
+       struct scsiback_tport *tport;
+       /* Returned by scsiback_make_tpg() */
+       struct se_portal_group se_tpg;
+       /* alias used in xenstore */
+       char param_alias[VSCSI_NAMELEN];
+       /* list of info structures related to this target portal group */
+       struct list_head info_list;
+};
+
+#define scsiback_get(_b) (atomic_inc(&(_b)->nr_unreplied_reqs))
+#define scsiback_put(_b)                               \
+       do {                                            \
+               if (atomic_dec_and_test(&(_b)->nr_unreplied_reqs))      \
+                       wake_up(&(_b)->waiting_to_free);\
+       } while (0)
+
+#define VSCSI_TIMEOUT          (900*HZ)
+
+#define VSCSI_TYPE_HOST                1
+
+/* Number of SCSI op_code      */
+#define VSCSI_MAX_SCSI_OP_CODE         256
+
+#define SCSIBACK_INVALID_HANDLE (~0)
+
+static bool log_print_stat;
+module_param(log_print_stat, bool, 0644);
+
+static int scsiback_max_buffer_pages = 1024;
+module_param_named(max_buffer_pages, scsiback_max_buffer_pages, int, 0644);
+MODULE_PARM_DESC(max_buffer_pages,
+"Maximum number of free pages to keep in backend buffer");
+
+static struct kmem_cache *scsiback_cachep;
+static DEFINE_SPINLOCK(free_pages_lock);
+static int free_pages_num;
+static LIST_HEAD(scsiback_free_pages);
+
+/* Global spinlock to protect scsiback TPG list */
+static DEFINE_MUTEX(scsiback_mutex);
+static LIST_HEAD(scsiback_list);
+
+/* Local pointer to allocated TCM configfs fabric module */
+static struct target_fabric_configfs *scsiback_fabric_configfs;
+
+static void put_free_pages(struct page **page, int num)
+{
+       unsigned long flags;
+       int i = free_pages_num + num, n = num;
+
+       if (num == 0)
+               return;
+       if (i > scsiback_max_buffer_pages) {
+               n = min(num, i - scsiback_max_buffer_pages);
+               free_xenballooned_pages(n, page + num - n);
+               n = num - n;
+       }
+       spin_lock_irqsave(&free_pages_lock, flags);
+       for (i = 0; i < n; i++)
+               list_add(&page[i]->lru, &scsiback_free_pages);
+       free_pages_num += n;
+       spin_unlock_irqrestore(&free_pages_lock, flags);
+}
+
+static int get_free_page(struct page **page)
+{
+       unsigned long flags;
+
+       spin_lock_irqsave(&free_pages_lock, flags);
+       if (list_empty(&scsiback_free_pages)) {
+               spin_unlock_irqrestore(&free_pages_lock, flags);
+               return alloc_xenballooned_pages(1, page, false);
+       }
+       page[0] = list_first_entry(&scsiback_free_pages, struct page, lru);
+       list_del(&page[0]->lru);
+       free_pages_num--;
+       spin_unlock_irqrestore(&free_pages_lock, flags);
+       return 0;
+}
+
+static unsigned long vaddr_page(struct page *page)
+{
+       unsigned long pfn = page_to_pfn(page);
+
+       return (unsigned long)pfn_to_kaddr(pfn);
+}
+
+static unsigned long vaddr(struct vscsibk_pend *req, int seg)
+{
+       return vaddr_page(req->pages[seg]);
+}
+
+static void scsiback_resp_err(struct vscsibk_pend *pending_req, uint16_t asc)
+{
+       pending_req->sense_buffer[0] = 0x70;    /* fixed, current */
+       pending_req->sense_buffer[2] = ILLEGAL_REQUEST;
+       pending_req->sense_buffer[7] = 0xa;     /* implies 18 bytes sense */
+       pending_req->sense_buffer[12] = asc >> 8;
+       pending_req->sense_buffer[13] = asc & 0xff;
+       pending_req->se_cmd.residual_count = 0;
+       pending_req->result = (DRIVER_SENSE << 24) | SAM_STAT_CHECK_CONDITION;
+}
+
+static void resp_not_supported_cmd(struct vscsibk_pend *pending_req, void 
*data)
+{
+       scsiback_resp_err(pending_req, scsi_invalid_command_operation_code);
+}
+
+static int __copy_to_sg(struct scatterlist *sgl, unsigned int nr_sg,
+              void *buf, unsigned int buflen, unsigned int off)
+{
+       struct scatterlist *sg;
+       void *from = buf;
+       void *to;
+       unsigned int from_rest = buflen;
+       unsigned int off_rest = off;
+       unsigned int to_capa;
+       unsigned int copy_size = 0;
+       unsigned int i;
+       unsigned long pfn;
+
+       for_each_sg(sgl, sg, nr_sg, i) {
+               if (sg_page(sg) == NULL) {
+                       pr_warn("%s: inconsistent length field in 
scatterlist\n",
+                               __func__);
+                       return -ENOMEM;
+               }
+
+               if (off_rest >= sg->length) {
+                       off_rest -= sg->length;
+                       continue;
+               }
+
+               to_capa  = sg->length - off_rest;
+               copy_size = min_t(unsigned int, to_capa, from_rest);
+
+               pfn = page_to_pfn(sg_page(sg));
+               to = pfn_to_kaddr(pfn) + (sg->offset) + off_rest;
+               memcpy(to, from, copy_size);
+
+               off_rest = 0;
+               from_rest  -= copy_size;
+               if (from_rest == 0)
+                       return 0;
+
+               from += copy_size;
+       }
+
+       return -ENOMEM;
+}
+
+static int __maybe_unused __copy_from_sg(struct scatterlist *sgl,
+                                        unsigned int nr_sg, void *buf,
+                                        unsigned int buflen)
+{
+       struct scatterlist *sg;
+       void *from;
+       void *to = buf;
+       unsigned int from_rest;
+       unsigned int to_capa = buflen;
+       unsigned int copy_size;
+       unsigned int i;
+       unsigned long pfn;
+
+       for_each_sg(sgl, sg, nr_sg, i) {
+               if (sg_page(sg) == NULL) {
+                       pr_warn("%s: inconsistent length field in 
scatterlist\n",
+                               __func__);
+                       return -ENOMEM;
+               }
+
+               from_rest = sg->length;
+               if ((from_rest > 0) && (to_capa < from_rest)) {
+                       pr_warn("%s: no space in destination buffer\n",
+                               __func__);
+                       return -ENOMEM;
+               }
+               copy_size = from_rest;
+
+               pfn = page_to_pfn(sg_page(sg));
+               from = pfn_to_kaddr(pfn) + (sg->offset);
+               memcpy(to, from, copy_size);
+
+               to_capa  -= copy_size;
+               to += copy_size;
+       }
+
+       return 0;
+}
+
+/* REPORT LUNS Define*/
+#define VSCSI_REPORT_LUNS_HEADER       8
+
+/* quoted scsi_debug.c/resp_report_luns() */
+static void __report_luns(struct vscsibk_pend *pending_req, void *data)
+{
+       struct vscsibk_info *info = pending_req->info;
+       unsigned int nr_seg  = pending_req->n_sg;
+       uint8_t *cmd = pending_req->cmnd;
+       unsigned char buff[VSCSI_REPORT_LUNS_HEADER];
+       unsigned int req_bufflen;
+       unsigned int actual_len = VSCSI_REPORT_LUNS_HEADER;
+       uint8_t select_report = cmd[2];
+       int i, lun_cnt = 0, lun;
+       struct v2p_entry *entry;
+       struct list_head *head = &(info->v2p_entry_lists);
+       unsigned long flags;
+       struct scsi_lun one_lun;
+       uint16_t v_chn, v_tgt;
+
+       req_bufflen = be32_to_cpup((const __be32 *)(cmd + 6));
+       if ((req_bufflen < 4) || (select_report != 0)) {
+               scsiback_resp_err(pending_req, scsi_invalid_field_in_cdb);
+               return;
+       }
+
+       memset(buff, 0, VSCSI_REPORT_LUNS_HEADER);
+       memset(&one_lun, 0, sizeof(one_lun));
+
+       v_chn = pending_req->v2p->v.chn;
+       v_tgt = pending_req->v2p->v.tgt;
+
+       spin_lock_irqsave(&info->v2p_lock, flags);
+       list_for_each_entry(entry, head, l) {
+               if ((entry->v.chn == v_chn) && (entry->v.tgt == v_tgt)) {
+                       lun = entry->v.lun;
+                       one_lun.scsi_lun[0] = (lun >> 8) & 0x3f;
+                       one_lun.scsi_lun[1] = lun & 0xff;
+                       lun_cnt++;
+                       __copy_to_sg(pending_req->sgl, nr_seg, &one_lun,
+                               sizeof(one_lun), actual_len);
+                       actual_len += sizeof(one_lun);
+               }
+       }
+
+       spin_unlock_irqrestore(&info->v2p_lock, flags);
+
+       buff[2] = ((sizeof(struct scsi_lun) * lun_cnt) >> 8) & 0xff;
+       buff[3] = (sizeof(struct scsi_lun) * lun_cnt) & 0xff;
+
+       __copy_to_sg(pending_req->sgl, nr_seg, buff,
+                       VSCSI_REPORT_LUNS_HEADER, 0);
+
+       req_bufflen = 0;
+       for (i = 0; i < nr_seg; i++)
+               req_bufflen += pending_req->sgl[i].length;
+
+       memset(pending_req->sense_buffer, 0, VSCSIIF_SENSE_BUFFERSIZE);
+       pending_req->result = 0x00;
+       pending_req->se_cmd.residual_count = req_bufflen -
+                                            min(req_bufflen, actual_len);
+}
+
+/*
+  Emulation routines for each SCSI op_code.
+*/
+static struct vscsibk_emulate emul[VSCSI_MAX_SCSI_OP_CODE] = {
+       /*
+         Register appropriate functions below as you need.
+         (See scsi/scsi.h for definition of SCSI op_code.)
+       */
+       [TEST_UNIT_READY]               = { NULL, NULL },  /*0x00 sd,st */
+       [REZERO_UNIT]                   = { NULL, NULL },  /*0x01 st */
+       [0x02]                          = { resp_not_supported_cmd, NULL },
+       [REQUEST_SENSE]                 = { NULL, NULL },  /*0x03*/
+       [FORMAT_UNIT]                   = { NULL, NULL },  /*0x04*/
+       [READ_BLOCK_LIMITS]             = { NULL, NULL },  /*0x05 st */
+       [0x06]                          = { resp_not_supported_cmd, NULL },
+       [INITIALIZE_ELEMENT_STATUS]     = { NULL, NULL },  /*0x07 ch */
+       [READ_6]                        = { NULL, NULL },  /*0x08 sd,st */
+       [0x09]                          = { resp_not_supported_cmd, NULL },
+       [WRITE_6]                       = { NULL, NULL },  /*0x0a sd,st */
+       [SEEK_6]                        = { NULL, NULL },  /*0x0b*/
+       [0x0c ... 0x0e]                 = { resp_not_supported_cmd, NULL },
+       [READ_REVERSE]                  = { resp_not_supported_cmd, NULL },
+       [WRITE_FILEMARKS]               = { NULL, NULL },  /*0x10 st */
+       [SPACE]                         = { NULL, NULL },  /*0x11 st */
+       [INQUIRY]                       = { NULL, NULL },  /*0x12*/
+       [0x13]                          = { resp_not_supported_cmd, NULL },
+       [RECOVER_BUFFERED_DATA]         = { resp_not_supported_cmd, NULL },
+       [MODE_SELECT]                   = { NULL, NULL },  /*0x15 st */
+       [RESERVE]                       = { NULL, NULL },  /*0x16*/
+       [RELEASE]                       = { NULL, NULL },  /*0x17*/
+       [COPY]                          = { resp_not_supported_cmd, NULL },
+       [ERASE]                         = { NULL, NULL },  /*0x19 st */
+       [MODE_SENSE]                    = { NULL, NULL },  /*0x1a st */
+       [START_STOP]                    = { NULL, NULL },  /*0x1b sd,st */
+       [RECEIVE_DIAGNOSTIC]            = { NULL, NULL },  /*0x1c*/
+       [SEND_DIAGNOSTIC]               = { NULL, NULL },  /*0x1d*/
+       [ALLOW_MEDIUM_REMOVAL]          = { NULL, NULL },  /*0x1e*/
+       [0x1f ... 0x22]                 = { resp_not_supported_cmd, NULL },
+       [READ_FORMAT_CAPACITIES]        = { resp_not_supported_cmd, NULL },
+       [SET_WINDOW]                    = { resp_not_supported_cmd, NULL },
+       [READ_CAPACITY]                 = { NULL, NULL },  /*0x25 sd */
+       [0x26 ... 0x27]                 = { resp_not_supported_cmd, NULL },
+       [READ_10]                       = { NULL, NULL },  /*0x28 sd */
+       [0x29]                          = { resp_not_supported_cmd, NULL },
+       [WRITE_10]                      = { NULL, NULL },  /*0x2a sd */
+       [SEEK_10]                       = { NULL, NULL },  /*0x2b st */
+       /*[POSITION_TO_ELEMENT]         = { NULL, NULL },    0x2b ch */
+       [0x2c ... 0x2d]                 = { resp_not_supported_cmd, NULL },
+       [WRITE_VERIFY]                  = { resp_not_supported_cmd, NULL },
+       [VERIFY]                        = { resp_not_supported_cmd, NULL },
+       [SEARCH_HIGH]                   = { resp_not_supported_cmd, NULL },
+       [SEARCH_EQUAL]                  = { resp_not_supported_cmd, NULL },
+       [SEARCH_LOW]                    = { resp_not_supported_cmd, NULL },
+       [SET_LIMITS]                    = { NULL, NULL },  /*0x33*/
+       [PRE_FETCH]                     = { NULL, NULL },  /*0x34 st */
+       /*[READ_POSITION]               = { NULL, NULL },    0x34 st */
+       [SYNCHRONIZE_CACHE]             = { NULL, NULL },  /*0x35 sd */
+       [LOCK_UNLOCK_CACHE]             = { NULL, NULL },  /*0x36*/
+       [READ_DEFECT_DATA]              = { NULL, NULL },  /*0x37*/
+       [MEDIUM_SCAN]                   = { NULL, NULL },  /*0x38*/
+       [COMPARE]                       = { resp_not_supported_cmd, NULL },
+       [COPY_VERIFY]                   = { resp_not_supported_cmd, NULL },
+       [WRITE_BUFFER]                  = { NULL, NULL },  /*0x3b*/
+       [READ_BUFFER]                   = { NULL, NULL },  /*0x3c osst */
+       [UPDATE_BLOCK]                  = { resp_not_supported_cmd, NULL },
+       [READ_LONG]                     = { resp_not_supported_cmd, NULL },
+       [WRITE_LONG]                    = { resp_not_supported_cmd, NULL },
+       [CHANGE_DEFINITION]             = { resp_not_supported_cmd, NULL },
+       [WRITE_SAME]                    = { resp_not_supported_cmd, NULL },
+       [UNMAP]                         = { resp_not_supported_cmd, NULL },
+       [READ_TOC]                      = { NULL, NULL },  /*0x43 sr */
+       [READ_HEADER]                   = { resp_not_supported_cmd, NULL },
+       [0x45 ... 0x49]                 = { resp_not_supported_cmd, NULL },
+       [GET_EVENT_STATUS_NOTIFICATION] = { resp_not_supported_cmd, NULL },
+       [0x4b]                          = { resp_not_supported_cmd, NULL },
+       [LOG_SELECT]                    = { NULL, NULL },  /*0x4c*/
+       [LOG_SENSE]                     = { NULL, NULL },  /*0x4d st */
+       [0x4e ... 0x52]                 = { resp_not_supported_cmd, NULL },
+       [XDWRITEREAD_10]                = { resp_not_supported_cmd, NULL },
+       [0x54]                          = { resp_not_supported_cmd, NULL },
+       [MODE_SELECT_10]                = { resp_not_supported_cmd, NULL },
+       [RESERVE_10]                    = { resp_not_supported_cmd, NULL },
+       [RELEASE_10]                    = { resp_not_supported_cmd, NULL },
+       [0x58 ... 0x59]                 = { resp_not_supported_cmd, NULL },
+       [MODE_SENSE_10]                 = { NULL, NULL },  /*0x5a scsi_lib */
+       [0x5b ... 0x5d]                 = { resp_not_supported_cmd, NULL },
+       [PERSISTENT_RESERVE_IN]         = { resp_not_supported_cmd, NULL },
+       [PERSISTENT_RESERVE_OUT]        = { resp_not_supported_cmd, NULL },
+       [0x60 ... 0x7e]                 = { resp_not_supported_cmd, NULL },
+       [VARIABLE_LENGTH_CMD]           = { resp_not_supported_cmd, NULL },
+       [0x80 ... 0x82]                 = { resp_not_supported_cmd, NULL },
+       [EXTENDED_COPY]                 = { resp_not_supported_cmd, NULL },
+       [RECEIVE_COPY_RESULTS]          = { resp_not_supported_cmd, NULL },
+       [0x85]                          = { resp_not_supported_cmd, NULL },
+       [ACCESS_CONTROL_IN]             = { resp_not_supported_cmd, NULL },
+       [ACCESS_CONTROL_OUT]            = { resp_not_supported_cmd, NULL },
+       [READ_16]                       = { NULL, NULL },  /*0x88 sd >2TB */
+       [COMPARE_AND_WRITE]             = { resp_not_supported_cmd, NULL },
+       [WRITE_16]                      = { NULL, NULL },  /*0x8a sd >2TB */
+       [0x8b]                          = { resp_not_supported_cmd, NULL },
+       [READ_ATTRIBUTE]                = { resp_not_supported_cmd, NULL },
+       [WRITE_ATTRIBUTE]               = { resp_not_supported_cmd, NULL },
+       [0x8e]                          = { resp_not_supported_cmd, NULL },
+       [VERIFY_16]                     = { NULL, NULL },  /*0x8f*/
+       [0x90]                          = { resp_not_supported_cmd, NULL },
+       [SYNCHRONIZE_CACHE_16]          = { resp_not_supported_cmd, NULL },
+       [0x92]                          = { resp_not_supported_cmd, NULL },
+       [WRITE_SAME_16]                 = { resp_not_supported_cmd, NULL },
+       [0x94 ... 0x9d]                 = { resp_not_supported_cmd, NULL },
+       [SERVICE_ACTION_IN]             = { NULL, NULL },  /*0x9e sd >2TB */
+       [0x9f]                          = { resp_not_supported_cmd, NULL },
+       [REPORT_LUNS]                   = { __report_luns, NULL }, /* emulate */
+       [0xa1]                          = { resp_not_supported_cmd, NULL },
+       [SECURITY_PROTOCOL_IN]          = { resp_not_supported_cmd, NULL },
+       [MAINTENANCE_IN]                = { NULL, NULL },  /*0xa3 IFT alua */
+       [MAINTENANCE_OUT]               = { NULL, NULL },  /*0xa4 IFT alua */
+       [MOVE_MEDIUM]                   = { NULL, NULL },  /*0xa5 ch */
+       [EXCHANGE_MEDIUM]               = { NULL, NULL },  /*0xa6 ch */
+       [0xa7]                          = { resp_not_supported_cmd, NULL },
+       [READ_12]                       = { resp_not_supported_cmd, NULL },
+       [0xa9]                          = { resp_not_supported_cmd, NULL },
+       [WRITE_12]                      = { resp_not_supported_cmd, NULL },
+       [READ_MEDIA_SERIAL_NUMBER]      = { resp_not_supported_cmd, NULL },
+       [0xac, 0xad]                    = { resp_not_supported_cmd, NULL },
+       [WRITE_VERIFY_12]               = { resp_not_supported_cmd, NULL },
+       [VERIFY_12]                     = { resp_not_supported_cmd, NULL },
+       [SEARCH_HIGH_12]                = { resp_not_supported_cmd, NULL },
+       [SEARCH_EQUAL_12]               = { resp_not_supported_cmd, NULL },
+       [SEARCH_LOW_12]                 = { resp_not_supported_cmd, NULL },
+       [0xb3 ... 0xb4]                 = { resp_not_supported_cmd, NULL },
+       [SECURITY_PROTOCOL_OUT]         = { resp_not_supported_cmd, NULL },
+       [SEND_VOLUME_TAG]               = { NULL, NULL },  /*0xb6 ch */
+       [0xb7]                          = { resp_not_supported_cmd, NULL },
+       [READ_ELEMENT_STATUS]           = { NULL, NULL },  /*0xb8 ch */
+       [0xb9 ... 0xe9]                 = { resp_not_supported_cmd, NULL },
+       [WRITE_LONG_2]                  = { resp_not_supported_cmd, NULL },
+       [0xeb ... 0xff]                 = { resp_not_supported_cmd, NULL },
+
+/* st: QFA_REQUEST_BLOCK, QFA_SEEK_BLOCK might be needed ? */
+
+};
+
+static void scsiback_rsp_emulation(struct vscsibk_pend *pending_req)
+{
+       uint8_t op_code = pending_req->cmnd[0];
+
+       if (emul[op_code].post_function != NULL)
+               emul[op_code].post_function(pending_req, NULL);
+}
+
+static void scsiback_print_status(char *sense_buffer, int errors,
+                                       struct vscsibk_pend *pending_req)
+{
+       struct scsiback_tpg *tpg = pending_req->v2p->tpg;
+
+       pr_err("xen-pvscsi[%s:%d] cmnd[0]=%02x -> st=%02x msg=%02x host=%02x 
drv=%02x\n",
+              tpg->tport->tport_name, pending_req->v2p->lun,
+              pending_req->cmnd[0], status_byte(errors), msg_byte(errors),
+              host_byte(errors), driver_byte(errors));
+
+       if (CHECK_CONDITION & status_byte(errors))
+               __scsi_print_sense("xen-pvscsi", sense_buffer,
+                                  SCSI_SENSE_BUFFERSIZE);
+}
+
+static void scsiback_fast_flush_area(struct vscsibk_pend *req)
+{
+       struct gnttab_unmap_grant_ref unmap[VSCSI_GRANT_BATCH];
+       struct page *pages[VSCSI_GRANT_BATCH];
+       unsigned int i, invcount = 0;
+       grant_handle_t handle;
+       int err;
+
+       kfree(req->sgl);
+       req->sgl = NULL;
+       req->n_sg = 0;
+
+       if (!req->n_grants)
+               return;
+
+       for (i = 0; i < req->n_grants; i++) {
+               handle = req->grant_handles[i];
+               if (handle == SCSIBACK_INVALID_HANDLE)
+                       continue;
+               gnttab_set_unmap_op(&unmap[invcount], vaddr(req, i),
+                                   GNTMAP_host_map, handle);
+               req->grant_handles[i] = SCSIBACK_INVALID_HANDLE;
+               pages[invcount] = req->pages[i];
+               put_page(pages[invcount]);
+               invcount++;
+               if (invcount < VSCSI_GRANT_BATCH)
+                       continue;
+               err = gnttab_unmap_refs(unmap, NULL, pages, invcount);
+               BUG_ON(err);
+               invcount = 0;
+       }
+
+       if (invcount) {
+               err = gnttab_unmap_refs(unmap, NULL, pages, invcount);
+               BUG_ON(err);
+       }
+
+       put_free_pages(req->pages, req->n_grants);
+       req->n_grants = 0;
+}
+
+static void scsiback_free_translation_entry(struct kref *kref)
+{
+       struct v2p_entry *entry = container_of(kref, struct v2p_entry, kref);
+       struct scsiback_tpg *tpg = entry->tpg;
+
+       mutex_lock(&tpg->tv_tpg_mutex);
+       tpg->tv_tpg_fe_count--;
+       mutex_unlock(&tpg->tv_tpg_mutex);
+
+       kfree(entry);
+}
+
+static void scsiback_do_resp_with_sense(char *sense_buffer, int32_t result,
+                       uint32_t resid, struct vscsibk_pend *pending_req)
+{
+       struct vscsiif_response *ring_res;
+       struct vscsibk_info *info = pending_req->info;
+       int notify;
+       struct scsi_sense_hdr sshdr;
+       unsigned long flags;
+       unsigned len;
+
+       DPRINTK("%s\n", __func__);
+
+       spin_lock_irqsave(&info->ring_lock, flags);
+
+       ring_res = RING_GET_RESPONSE(&info->ring, info->ring.rsp_prod_pvt);
+       info->ring.rsp_prod_pvt++;
+
+       ring_res->rslt   = result;
+       ring_res->rqid   = pending_req->rqid;
+
+       if (sense_buffer != NULL &&
+           scsi_normalize_sense(sense_buffer, VSCSIIF_SENSE_BUFFERSIZE,
+                                &sshdr)) {
+               len = min_t(unsigned, 8 + sense_buffer[7],
+                           VSCSIIF_SENSE_BUFFERSIZE);
+               memcpy(ring_res->sense_buffer, sense_buffer, len);
+               ring_res->sense_len = len;
+       } else {
+               ring_res->sense_len = 0;
+       }
+
+       ring_res->residual_len = resid;
+
+       RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&info->ring, notify);
+       spin_unlock_irqrestore(&info->ring_lock, flags);
+
+       if (notify)
+               notify_remote_via_irq(info->irq);
+
+       if (pending_req->v2p)
+               kref_put(&pending_req->v2p->kref,
+                        scsiback_free_translation_entry);
+
+       kmem_cache_free(scsiback_cachep, pending_req);
+}
+
+static void scsiback_cmd_done(struct vscsibk_pend *pending_req)
+{
+       struct vscsibk_info *info = pending_req->info;
+       unsigned char *sense_buffer;
+       unsigned int resid;
+       int errors;
+
+       sense_buffer = pending_req->sense_buffer;
+       resid        = pending_req->se_cmd.residual_count;
+       errors       = pending_req->result;
+
+       if (errors && log_print_stat)
+               scsiback_print_status(sense_buffer, errors, pending_req);
+
+       /* The Host mode is through as for Emulation. */
+       if (info->feature != VSCSI_TYPE_HOST)
+               scsiback_rsp_emulation(pending_req);
+
+       scsiback_fast_flush_area(pending_req);
+       scsiback_do_resp_with_sense(sense_buffer, errors, resid, pending_req);
+       scsiback_put(info);
+
+       transport_generic_free_cmd(&pending_req->se_cmd, 0);
+}
+
+static void scsiback_cmd_exec(struct vscsibk_pend *pending_req)
+{
+       struct se_cmd *se_cmd = &pending_req->se_cmd;
+       struct se_session *sess = pending_req->v2p->tpg->tpg_nexus->tvn_se_sess;
+       int rc;
+
+       DPRINTK("%s\n", __func__);
+
+       memset(pending_req->sense_buffer, 0, VSCSIIF_SENSE_BUFFERSIZE);
+
+       memset(se_cmd, 0, sizeof(*se_cmd));
+       se_cmd->prot_pto = true;
+
+       scsiback_get(pending_req->info);
+       rc = target_submit_cmd_map_sgls(se_cmd, sess, pending_req->cmnd,
+                       pending_req->sense_buffer, pending_req->v2p->lun,
+                       pending_req->data_len, 0,
+                       pending_req->sc_data_direction, 0,
+                       pending_req->sgl, pending_req->n_sg,
+                       NULL, 0, NULL, 0);
+       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 int scsiback_gnttab_data_map_batch(struct gnttab_map_grant_ref *map,
+       struct page **pg, grant_handle_t *grant, int cnt)
+{
+       int err, i;
+
+       if (!cnt)
+               return 0;
+
+       err = gnttab_map_refs(map, NULL, pg, cnt);
+       BUG_ON(err);
+       for (i = 0; i < cnt; i++) {
+               if (unlikely(map[i].status != GNTST_okay)) {
+                       pr_err("xen-pvscsi: invalid buffer -- could not remap 
it\n");
+                       map[i].handle = SCSIBACK_INVALID_HANDLE;
+                       err = -ENOMEM;
+               } else {
+                       get_page(pg[i]);
+               }
+               grant[i] = map[i].handle;
+       }
+       return err;
+}
+
+static int scsiback_gnttab_data_map_list(struct vscsibk_pend *pending_req,
+                       struct scsiif_request_segment *seg, struct page **pg,
+                       grant_handle_t *grant, int cnt, u32 flags)
+{
+       int mapcount = 0, i, err = 0;
+       struct gnttab_map_grant_ref map[VSCSI_GRANT_BATCH];
+       struct vscsibk_info *info = pending_req->info;
+
+       for (i = 0; i < cnt; i++) {
+               if (get_free_page(pg + mapcount)) {
+                       put_free_pages(pg, mapcount);
+                       pr_err("xen-pvscsi: no grant page\n");
+                       return -ENOMEM;
+               }
+               gnttab_set_map_op(&map[mapcount], vaddr_page(pg[mapcount]),
+                                 flags, seg[i].gref, info->domid);
+               mapcount++;
+               if (mapcount < VSCSI_GRANT_BATCH)
+                       continue;
+               err = scsiback_gnttab_data_map_batch(map, pg, grant, mapcount);
+               pg += mapcount;
+               grant += mapcount;
+               pending_req->n_grants += mapcount;
+               if (err)
+                       return err;
+               mapcount = 0;
+       }
+       err = scsiback_gnttab_data_map_batch(map, pg, grant, mapcount);
+       pending_req->n_grants += mapcount;
+       return err;
+}
+
+static int scsiback_gnttab_data_map(struct vscsiif_request *ring_req,
+                                       struct vscsibk_pend *pending_req)
+{
+       u32 flags;
+       int i, err, n_segs, i_seg = 0;
+       struct page **pg;
+       struct scsiif_request_segment *seg;
+       unsigned long end_seg = 0;
+       unsigned int nr_segments = (unsigned int)ring_req->nr_segments;
+       unsigned int nr_sgl = 0;
+       struct scatterlist *sg;
+       grant_handle_t *grant;
+
+       pending_req->n_sg = 0;
+       pending_req->n_grants = 0;
+       pending_req->data_len = 0;
+
+       nr_segments &= ~VSCSIIF_SG_GRANT;
+       if (!nr_segments)
+               return 0;
+
+       if (nr_segments > VSCSIIF_SG_TABLESIZE) {
+               DPRINTK("xen-pvscsi: invalid parameter nr_seg = %d\n",
+                       ring_req->nr_segments);
+               return -EINVAL;
+       }
+
+       if (ring_req->nr_segments & VSCSIIF_SG_GRANT) {
+               err = scsiback_gnttab_data_map_list(pending_req, ring_req->seg,
+                       pending_req->pages, pending_req->grant_handles,
+                       nr_segments, GNTMAP_host_map | GNTMAP_readonly);
+               if (err)
+                       return err;
+               nr_sgl = nr_segments;
+               nr_segments = 0;
+               for (i = 0; i < nr_sgl; i++) {
+                       n_segs = ring_req->seg[i].length /
+                                sizeof(struct scsiif_request_segment);
+                       if ((unsigned)ring_req->seg[i].offset +
+                           (unsigned)ring_req->seg[i].length > PAGE_SIZE ||
+                           n_segs * sizeof(struct scsiif_request_segment) !=
+                           ring_req->seg[i].length)
+                               return -EINVAL;
+                       nr_segments += n_segs;
+               }
+               if (nr_segments > SG_ALL) {
+                       DPRINTK("xen-pvscsi: invalid nr_seg = %d\n",
+                               nr_segments);
+                       return -EINVAL;
+               }
+       }
+
+       /* free of (sgl) in fast_flush_area()*/
+       pending_req->sgl = kmalloc_array(nr_segments,
+                                       sizeof(struct scatterlist), GFP_KERNEL);
+       if (!pending_req->sgl) {
+               pr_err("xen-pvscsi: %s: kmalloc() error\n", __func__);
+               return -ENOMEM;
+       }
+
+       sg_init_table(pending_req->sgl, nr_segments);
+       pending_req->n_sg = nr_segments;
+
+       flags = GNTMAP_host_map;
+       if (pending_req->sc_data_direction == DMA_TO_DEVICE)
+               flags |= GNTMAP_readonly;
+
+       pg = pending_req->pages + nr_sgl;
+       grant = pending_req->grant_handles + nr_sgl;
+       if (!nr_sgl) {
+               seg = ring_req->seg;
+               err = scsiback_gnttab_data_map_list(pending_req, seg,
+                       pg, grant, nr_segments, flags);
+               if (err)
+                       return err;
+       } else {
+               for (i = 0; i < nr_sgl; i++) {
+                       seg = (struct scsiif_request_segment *)(
+                             vaddr(pending_req, i) + ring_req->seg[i].offset);
+                       n_segs = ring_req->seg[i].length /
+                                sizeof(struct scsiif_request_segment);
+                       err = scsiback_gnttab_data_map_list(pending_req, seg,
+                               pg, grant, n_segs, flags);
+                       if (err)
+                               return err;
+                       pg += n_segs;
+                       grant += n_segs;
+               }
+               end_seg = vaddr(pending_req, 0) + ring_req->seg[0].offset;
+               seg = (struct scsiif_request_segment *)end_seg;
+               end_seg += ring_req->seg[0].length;
+               pg = pending_req->pages + nr_sgl;
+       }
+
+       for_each_sg(pending_req->sgl, sg, nr_segments, i) {
+               sg_set_page(sg, pg[i], seg->length, seg->offset);
+               pending_req->data_len += seg->length;
+               seg++;
+               if (nr_sgl && (unsigned long)seg >= end_seg) {
+                       i_seg++;
+                       end_seg = vaddr(pending_req, i_seg) +
+                                 ring_req->seg[i_seg].offset;
+                       seg = (struct scsiif_request_segment *)end_seg;
+                       end_seg += ring_req->seg[i_seg].length;
+               }
+               barrier();
+               if (sg->offset >= PAGE_SIZE ||
+                   sg->length > PAGE_SIZE ||
+                   sg->offset + sg->length > PAGE_SIZE)
+                       return -EINVAL;
+       }
+
+       return 0;
+}
+
+static void scsiback_req_emulation_or_cmdexec(struct vscsiif_request *ring_req,
+                                            struct vscsibk_pend *pending_req)
+{
+       struct vscsibk_info *info = pending_req->info;
+       uint8_t op_code = pending_req->cmnd[0];
+
+       if (scsiback_gnttab_data_map(ring_req, pending_req))
+               goto out;
+
+       if (info->feature != VSCSI_TYPE_HOST && emul[op_code].pre_function) {
+               emul[op_code].pre_function(pending_req, NULL);
+               scsiback_fast_flush_area(pending_req);
+               scsiback_do_resp_with_sense(pending_req->sense_buffer,
+                       pending_req->result,
+                       pending_req->se_cmd.residual_count,
+                       pending_req);
+       } else {
+               scsiback_cmd_exec(pending_req);
+       }
+       return;
+
+out:
+       scsiback_fast_flush_area(pending_req);
+       scsiback_do_resp_with_sense(NULL, DRIVER_ERROR << 24, 0, pending_req);
+}
+
+static void scsiback_notify_work(struct vscsibk_info *info)
+{
+       info->waiting_reqs = 1;
+       wake_up(&info->wq);
+}
+
+static irqreturn_t scsiback_intr(int irq, void *dev_id)
+{
+       scsiback_notify_work((struct vscsibk_info *)dev_id);
+       return IRQ_HANDLED;
+}
+
+static int scsiback_init_sring(struct vscsibk_info *info, grant_ref_t ring_ref,
+                       evtchn_port_t evtchn)
+{
+       void *area;
+       struct vscsiif_sring *sring;
+       int err;
+
+       if (info->irq) {
+               pr_err("xen-pvscsi: Already connected through?\n");
+               return -1;
+       }
+
+       err = xenbus_map_ring_valloc(info->dev, ring_ref, &area);
+       if (err)
+               return err;
+
+       sring = (struct vscsiif_sring *)area;
+       BACK_RING_INIT(&info->ring, sring, PAGE_SIZE);
+
+       err = bind_interdomain_evtchn_to_irqhandler(
+                       info->domid, evtchn,
+                       scsiback_intr, 0, "vscsiif-backend", info);
+
+       if (err < 0)
+               goto unmap_page;
+
+       info->irq = err;
+
+       return 0;
+
+unmap_page:
+       xenbus_unmap_ring_vfree(info->dev, area);
+
+       return err;
+}
+
+static void scsiback_disconnect(struct vscsibk_info *info)
+{
+       if (info->kthread) {
+               kthread_stop(info->kthread);
+               info->kthread = NULL;
+               wake_up(&info->shutdown_wq);
+       }
+
+       wait_event(info->waiting_to_free,
+               atomic_read(&info->nr_unreplied_reqs) == 0);
+
+       if (info->irq) {
+               unbind_from_irqhandler(info->irq, info);
+               info->irq = 0;
+       }
+
+       if (info->ring.sring) {
+               xenbus_unmap_ring_vfree(info->dev, info->ring.sring);
+               info->ring.sring = NULL;
+       }
+}
+
+static void scsiback_device_action(struct vscsibk_pend *pending_req,
+       enum tcm_tmreq_table act)
+{
+       int rc, err = FAILED;
+       struct scsiback_tpg *tpg = pending_req->v2p->tpg;
+       struct se_cmd *se_cmd = &pending_req->se_cmd;
+       struct scsiback_tmr *tmr;
+
+       tmr = kzalloc(sizeof(struct scsiback_tmr), GFP_KERNEL);
+       if (!tmr) {
+               pr_err("xen-pvscsi: %s: kmalloc() error\n", __func__);
+               goto out;
+       }
+       init_waitqueue_head(&tmr->tmr_wait);
+
+       transport_init_se_cmd(se_cmd, tpg->se_tpg.se_tpg_tfo,
+               tpg->tpg_nexus->tvn_se_sess, 0, DMA_NONE, MSG_SIMPLE_TAG,
+               &pending_req->sense_buffer[0]);
+
+       rc = core_tmr_alloc_req(se_cmd, tmr, act, GFP_KERNEL);
+       if (rc < 0)
+               goto out;
+
+       se_cmd->se_tmr_req->ref_task_tag = 0;
+
+       if (transport_lookup_tmr_lun(se_cmd, pending_req->v2p->lun) < 0)
+               goto out;
+
+       transport_generic_handle_tmr(se_cmd);
+       wait_event(tmr->tmr_wait, atomic_read(&tmr->tmr_complete));
+
+       err = (se_cmd->se_tmr_req->response == TMR_FUNCTION_COMPLETE) ?
+               SUCCESS : FAILED;
+
+out:
+       if (tmr) {
+               transport_generic_free_cmd(&pending_req->se_cmd, 1);
+               kfree(tmr);
+       }
+
+       scsiback_do_resp_with_sense(NULL, err, 0, pending_req);
+}
+
+/*
+  Perform virtual to physical translation
+*/
+static struct v2p_entry *scsiback_do_translation(struct vscsibk_info *info,
+                       struct ids_tuple *v)
+{
+       struct v2p_entry *entry;
+       struct list_head *head = &(info->v2p_entry_lists);
+       unsigned long flags;
+
+       spin_lock_irqsave(&info->v2p_lock, flags);
+       list_for_each_entry(entry, head, l) {
+               if ((entry->v.chn == v->chn) &&
+                   (entry->v.tgt == v->tgt) &&
+                   (entry->v.lun == v->lun)) {
+                       kref_get(&entry->kref);
+                       goto out;
+               }
+       }
+       entry = NULL;
+
+out:
+       spin_unlock_irqrestore(&info->v2p_lock, flags);
+       return entry;
+}
+
+static int prepare_pending_reqs(struct vscsibk_info *info,
+                               struct vscsiif_request *ring_req,
+                               struct vscsibk_pend *pending_req)
+{
+       struct v2p_entry *v2p;
+       struct ids_tuple vir;
+
+       DPRINTK("%s\n", __func__);
+
+       pending_req->rqid       = ring_req->rqid;
+       pending_req->info       = info;
+
+       vir.chn = ring_req->channel;
+       vir.tgt = ring_req->id;
+       vir.lun = ring_req->lun;
+
+       v2p = scsiback_do_translation(info, &vir);
+       if (!v2p) {
+               pending_req->v2p = NULL;
+               DPRINTK("xen-pvscsi: doesn't exist.\n");
+               return -ENODEV;
+       }
+       pending_req->v2p = v2p;
+
+       /* request range check from frontend */
+       pending_req->sc_data_direction = ring_req->sc_data_direction;
+       if ((pending_req->sc_data_direction != DMA_BIDIRECTIONAL) &&
+               (pending_req->sc_data_direction != DMA_TO_DEVICE) &&
+               (pending_req->sc_data_direction != DMA_FROM_DEVICE) &&
+               (pending_req->sc_data_direction != DMA_NONE)) {
+               DPRINTK("xen-pvscsi: invalid parameter data_dir = %d\n",
+                       pending_req->sc_data_direction);
+               return -EINVAL;
+       }
+
+       pending_req->cmd_len = ring_req->cmd_len;
+       if (pending_req->cmd_len > VSCSIIF_MAX_COMMAND_SIZE) {
+               DPRINTK("xen-pvscsi: invalid parameter cmd_len = %d\n",
+                       pending_req->cmd_len);
+               return -EINVAL;
+       }
+       memcpy(pending_req->cmnd, ring_req->cmnd, pending_req->cmd_len);
+
+       return 0;
+}
+
+static int _scsiback_do_cmd_fn(struct vscsibk_info *info)
+{
+       struct vscsiif_back_ring *ring = &info->ring;
+       struct vscsiif_request *ring_req;
+       struct vscsibk_pend *pending_req;
+       RING_IDX rc, rp;
+       int err, more_to_do = 0;
+       uint32_t result;
+       uint8_t act;
+
+       DPRINTK("%s\n", __func__);
+
+       rc = ring->req_cons;
+       rp = ring->sring->req_prod;
+       rmb();  /* guest system is accessing ring, too */
+
+       if (RING_REQUEST_PROD_OVERFLOW(ring, rp)) {
+               rc = ring->rsp_prod_pvt;
+               pr_warn("xen-pvscsi: Dom%d provided bogus ring requests (%#x - 
%#x = %u). Halting ring processing\n",
+                          info->domid, rp, rc, rp - rc);
+               return -EACCES;
+       }
+
+       while ((rc != rp)) {
+               if (RING_REQUEST_CONS_OVERFLOW(ring, rc))
+                       break;
+               pending_req = kmem_cache_alloc(scsiback_cachep, GFP_KERNEL);
+               if (NULL == pending_req) {
+                       more_to_do = 1;
+                       break;
+               }
+
+               ring_req = RING_GET_REQUEST(ring, rc);
+               ring->req_cons = ++rc;
+
+               act = ring_req->act;
+               err = prepare_pending_reqs(info, ring_req, pending_req);
+               if (err) {
+                       switch (err) {
+                       case -ENODEV:
+                               result = DID_NO_CONNECT;
+                               break;
+                       default:
+                               result = DRIVER_ERROR;
+                               break;
+                       }
+                       scsiback_do_resp_with_sense(NULL, result << 24, 0,
+                                                   pending_req);
+                       more_to_do = 1;
+                       break;
+               }
+
+               switch (act) {
+               case VSCSIIF_ACT_SCSI_CDB:
+                       scsiback_req_emulation_or_cmdexec(ring_req,
+                                                         pending_req);
+                       break;
+               case VSCSIIF_ACT_SCSI_ABORT:
+                       scsiback_device_action(pending_req, TMR_ABORT_TASK);
+                       break;
+               case VSCSIIF_ACT_SCSI_RESET:
+                       scsiback_device_action(pending_req, TMR_LUN_RESET);
+                       break;
+               default:
+                       pr_err_ratelimited("xen-pvscsi: invalid request\n");
+                       scsiback_do_resp_with_sense(NULL, DRIVER_ERROR << 24,
+                                                   0, pending_req);
+                       break;
+               }
+
+               /* Yield point for this unbounded loop. */
+               cond_resched();
+       }
+
+       if (RING_HAS_UNCONSUMED_REQUESTS(ring))
+               more_to_do = 1;
+
+       return more_to_do;
+}
+
+static int scsiback_do_cmd_fn(struct vscsibk_info *info)
+{
+       int more_to_do;
+
+       do {
+               more_to_do = _scsiback_do_cmd_fn(info);
+               if (more_to_do)
+                       break;
+
+               RING_FINAL_CHECK_FOR_REQUESTS(&info->ring, more_to_do);
+       } while (more_to_do);
+
+       return more_to_do;
+}
+
+static int scsiback_schedule(void *data)
+{
+       struct vscsibk_info *info = (struct vscsibk_info *)data;
+
+       DPRINTK("%s\n", __func__);
+
+       while (!kthread_should_stop()) {
+               wait_event_interruptible(info->wq,
+                       info->waiting_reqs || kthread_should_stop());
+
+               info->waiting_reqs = 0;
+               smp_mb();       /* waiting_reqs used by other thread */
+
+               switch (scsiback_do_cmd_fn(info)) {
+               case 1:
+                       info->waiting_reqs = 1;
+               case 0:
+                       break;
+               case -EACCES:
+                       wait_event_interruptible(info->shutdown_wq,
+                                                kthread_should_stop());
+                       break;
+               default:
+                       BUG();
+               }
+       }
+
+       return 0;
+}
+
+static void __vscsiif_name(struct vscsibk_info *info, char *buf)
+{
+       struct xenbus_device *dev = info->dev;
+       unsigned int domid, id;
+
+       if (sscanf(dev->nodename, "backend/vscsi/%u/%u", &domid, &id) == 2)
+               snprintf(buf, TASK_COMM_LEN, "vscsi.%u.%u", info->domid, id);
+       else
+               snprintf(buf, TASK_COMM_LEN, "vscsi.%u..", info->domid);
+}
+
+static int scsiback_map(struct vscsibk_info *info)
+{
+       struct xenbus_device *dev = info->dev;
+       unsigned int ring_ref, evtchn;
+       int err;
+       char name[TASK_COMM_LEN];
+
+       err = xenbus_gather(XBT_NIL, dev->otherend,
+                       "ring-ref", "%u", &ring_ref,
+                       "event-channel", "%u", &evtchn, NULL);
+       if (err) {
+               xenbus_dev_fatal(dev, err, "reading %s ring", dev->otherend);
+               return err;
+       }
+
+       err = scsiback_init_sring(info, ring_ref, evtchn);
+       if (err)
+               return err;
+
+       __vscsiif_name(info, name);
+
+       info->kthread = kthread_run(scsiback_schedule, info, name);
+       if (IS_ERR(info->kthread)) {
+               err = PTR_ERR(info->kthread);
+               info->kthread = NULL;
+               xenbus_dev_error(info->dev, err, "start vscsiif");
+               return err;
+       }
+
+       return 0;
+}
+
+/*
+  Add a new translation entry
+*/
+static int scsiback_add_translation_entry(struct vscsibk_info *info,
+                                         char *phy, struct ids_tuple *v)
+{
+       int err = 0;
+       struct v2p_entry *entry;
+       struct v2p_entry *new;
+       struct list_head *head = &(info->v2p_entry_lists);
+       unsigned long flags;
+       char *lunp;
+       unsigned int lun;
+       struct scsiback_tpg *tpg_entry, *tpg = NULL;
+       char *error = "doesn't exist";
+
+       lunp = strrchr(phy, ':');
+       if (!lunp) {
+               pr_err("xen-pvscsi: illegal format of physical device %s\n",
+                       phy);
+               return -EINVAL;
+       }
+       *lunp = 0;
+       lunp++;
+       if (kstrtouint(lunp, 10, &lun) || lun >= TRANSPORT_MAX_LUNS_PER_TPG) {
+               pr_err("xen-pvscsi: lun number not valid: %s\n", lunp);
+               return -EINVAL;
+       }
+
+       mutex_lock(&scsiback_mutex);
+       list_for_each_entry(tpg_entry, &scsiback_list, tv_tpg_list) {
+               if (!strcmp(phy, tpg_entry->tport->tport_name) ||
+                   !strcmp(phy, tpg_entry->param_alias)) {
+                       spin_lock(&tpg_entry->se_tpg.tpg_lun_lock);
+                       if (tpg_entry->se_tpg.tpg_lun_list[lun]->lun_status ==
+                           TRANSPORT_LUN_STATUS_ACTIVE) {
+                               if (!tpg_entry->tpg_nexus)
+                                       error = "nexus undefined";
+                               else
+                                       tpg = tpg_entry;
+                       }
+                       spin_unlock(&tpg_entry->se_tpg.tpg_lun_lock);
+                       break;
+               }
+       }
+       if (tpg) {
+               mutex_lock(&tpg->tv_tpg_mutex);
+               tpg->tv_tpg_fe_count++;
+               mutex_unlock(&tpg->tv_tpg_mutex);
+       }
+       mutex_unlock(&scsiback_mutex);
+
+       if (!tpg) {
+               pr_err("xen-pvscsi: %s:%d %s\n", phy, lun, error);
+               return -ENODEV;
+       }
+
+       new = kmalloc(sizeof(struct v2p_entry), GFP_KERNEL);
+       if (new == NULL) {
+               pr_err("xen-pvscsi: %s: kmalloc() error\n", __func__);
+               err = -ENOMEM;
+               goto out_free;
+       }
+
+       spin_lock_irqsave(&info->v2p_lock, flags);
+
+       /* Check double assignment to identical virtual ID */
+       list_for_each_entry(entry, head, l) {
+               if ((entry->v.chn == v->chn) &&
+                   (entry->v.tgt == v->tgt) &&
+                   (entry->v.lun == v->lun)) {
+                       pr_warn("xen-pvscsi: Virtual ID is already used. 
Assignment was not performed.\n");
+                       err = -EEXIST;
+                       goto out;
+               }
+
+       }
+
+       /* Create a new translation entry and add to the list */
+       kref_init(&new->kref);
+       new->v = *v;
+       new->tpg = tpg;
+       new->lun = lun;
+       list_add_tail(&new->l, head);
+
+out:
+       spin_unlock_irqrestore(&info->v2p_lock, flags);
+
+out_free:
+       mutex_lock(&tpg->tv_tpg_mutex);
+       tpg->tv_tpg_fe_count--;
+       mutex_unlock(&tpg->tv_tpg_mutex);
+
+       if (err)
+               kfree(new);
+
+       return err;
+}
+
+static void __scsiback_del_translation_entry(struct v2p_entry *entry)
+{
+       list_del(&entry->l);
+       kref_put(&entry->kref, scsiback_free_translation_entry);
+       kfree(entry);
+}
+
+/*
+  Delete the translation entry specfied
+*/
+static int scsiback_del_translation_entry(struct vscsibk_info *info,
+                                         struct ids_tuple *v)
+{
+       struct v2p_entry *entry;
+       struct list_head *head = &(info->v2p_entry_lists);
+       unsigned long flags;
+
+       spin_lock_irqsave(&info->v2p_lock, flags);
+       /* Find out the translation entry specified */
+       list_for_each_entry(entry, head, l) {
+               if ((entry->v.chn == v->chn) &&
+                   (entry->v.tgt == v->tgt) &&
+                   (entry->v.lun == v->lun)) {
+                       goto found;
+               }
+       }
+
+       spin_unlock_irqrestore(&info->v2p_lock, flags);
+       return 1;
+
+found:
+       /* Delete the translation entry specfied */
+       __scsiback_del_translation_entry(entry);
+
+       spin_unlock_irqrestore(&info->v2p_lock, flags);
+       return 0;
+}
+
+static void scsiback_do_add_lun(struct vscsibk_info *info, const char *state,
+                               char *phy, struct ids_tuple *vir)
+{
+       if (!scsiback_add_translation_entry(info, phy, vir)) {
+               if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
+                                 "%d", XenbusStateInitialised)) {
+                       pr_err("xen-pvscsi: xenbus_printf error %s\n", state);
+                       scsiback_del_translation_entry(info, vir);
+               }
+       } else {
+               xenbus_printf(XBT_NIL, info->dev->nodename, state,
+                             "%d", XenbusStateClosed);
+       }
+}
+
+static void scsiback_do_del_lun(struct vscsibk_info *info, const char *state,
+                               struct ids_tuple *vir)
+{
+       if (!scsiback_del_translation_entry(info, vir)) {
+               if (xenbus_printf(XBT_NIL, info->dev->nodename, state,
+                                 "%d", XenbusStateClosed))
+                       pr_err("xen-pvscsi: xenbus_printf error %s\n", state);
+       }
+}
+
+#define VSCSIBACK_OP_ADD_OR_DEL_LUN    1
+#define VSCSIBACK_OP_UPDATEDEV_STATE   2
+
+static void scsiback_do_1lun_hotplug(struct vscsibk_info *info, int op,
+                                    char *ent)
+{
+       int err;
+       struct ids_tuple vir;
+       char *val;
+       int device_state;
+       char phy[VSCSI_NAMELEN];
+       char str[64];
+       char state[64];
+       struct xenbus_device *dev = info->dev;
+
+       /* read status */
+       snprintf(state, sizeof(state), "vscsi-devs/%s/state", ent);
+       err = xenbus_scanf(XBT_NIL, dev->nodename, state, "%u", &device_state);
+       if (XENBUS_EXIST_ERR(err))
+               return;
+
+       /* physical SCSI device */
+       snprintf(str, sizeof(str), "vscsi-devs/%s/p-dev", ent);
+       val = xenbus_read(XBT_NIL, dev->nodename, str, NULL);
+       if (IS_ERR(val)) {
+               xenbus_printf(XBT_NIL, dev->nodename, state,
+                             "%d", XenbusStateClosed);
+               return;
+       }
+       strlcpy(phy, val, VSCSI_NAMELEN);
+       kfree(val);
+
+       /* virtual SCSI device */
+       snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", ent);
+       err = xenbus_scanf(XBT_NIL, dev->nodename, str, "%u:%u:%u:%u",
+                          &vir.hst, &vir.chn, &vir.tgt, &vir.lun);
+       if (XENBUS_EXIST_ERR(err)) {
+               xenbus_printf(XBT_NIL, dev->nodename, state,
+                             "%d", XenbusStateClosed);
+               return;
+       }
+
+       switch (op) {
+       case VSCSIBACK_OP_ADD_OR_DEL_LUN:
+               if (device_state == XenbusStateInitialising)
+                       scsiback_do_add_lun(info, state, phy, &vir);
+               if (device_state == XenbusStateClosing)
+                       scsiback_do_del_lun(info, state, &vir);
+               break;
+
+       case VSCSIBACK_OP_UPDATEDEV_STATE:
+               if (device_state == XenbusStateInitialised) {
+                       /* modify vscsi-devs/dev-x/state */
+                       if (xenbus_printf(XBT_NIL, dev->nodename, state,
+                                         "%d", XenbusStateConnected)) {
+                               pr_err("xen-pvscsi: xenbus_printf error %s\n",
+                                      str);
+                               scsiback_del_translation_entry(info, &vir);
+                               xenbus_printf(XBT_NIL, dev->nodename, state,
+                                             "%d", XenbusStateClosed);
+                       }
+               }
+               break;
+       /*When it is necessary, processing is added here.*/
+       default:
+               break;
+       }
+}
+
+static void scsiback_do_lun_hotplug(struct vscsibk_info *info, int op)
+{
+       int i;
+       char **dir;
+       unsigned int ndir = 0;
+
+       dir = xenbus_directory(XBT_NIL, info->dev->nodename, "vscsi-devs",
+                              &ndir);
+       if (IS_ERR(dir))
+               return;
+
+       for (i = 0; i < ndir; i++)
+               scsiback_do_1lun_hotplug(info, op, dir[i]);
+
+       kfree(dir);
+}
+
+static void scsiback_frontend_changed(struct xenbus_device *dev,
+                                       enum xenbus_state frontend_state)
+{
+       struct vscsibk_info *info = dev_get_drvdata(&dev->dev);
+       int err;
+
+       switch (frontend_state) {
+       case XenbusStateInitialising:
+               break;
+       case XenbusStateInitialised:
+               err = scsiback_map(info);
+               if (err)
+                       break;
+
+               scsiback_do_lun_hotplug(info, VSCSIBACK_OP_ADD_OR_DEL_LUN);
+               xenbus_switch_state(dev, XenbusStateConnected);
+
+               break;
+       case XenbusStateConnected:
+
+               scsiback_do_lun_hotplug(info, VSCSIBACK_OP_UPDATEDEV_STATE);
+
+               if (dev->state == XenbusStateConnected)
+                       break;
+
+               xenbus_switch_state(dev, XenbusStateConnected);
+
+               break;
+
+       case XenbusStateClosing:
+               scsiback_disconnect(info);
+               xenbus_switch_state(dev, XenbusStateClosing);
+               break;
+
+       case XenbusStateClosed:
+               xenbus_switch_state(dev, XenbusStateClosed);
+               if (xenbus_dev_is_online(dev))
+                       break;
+               /* fall through if not online */
+       case XenbusStateUnknown:
+               device_unregister(&dev->dev);
+               break;
+
+       case XenbusStateReconfiguring:
+               scsiback_do_lun_hotplug(info, VSCSIBACK_OP_ADD_OR_DEL_LUN);
+
+               xenbus_switch_state(dev, XenbusStateReconfigured);
+
+               break;
+
+       default:
+               xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
+                                       frontend_state);
+               break;
+       }
+}
+
+/*
+  Release the translation entry specfied
+*/
+static void scsiback_release_translation_entry(struct vscsibk_info *info)
+{
+       struct v2p_entry *entry, *tmp;
+       struct list_head *head = &(info->v2p_entry_lists);
+       unsigned long flags;
+
+       spin_lock_irqsave(&info->v2p_lock, flags);
+
+       list_for_each_entry_safe(entry, tmp, head, l)
+               __scsiback_del_translation_entry(entry);
+
+       spin_unlock_irqrestore(&info->v2p_lock, flags);
+}
+
+static int scsiback_remove(struct xenbus_device *dev)
+{
+       struct vscsibk_info *info = dev_get_drvdata(&dev->dev);
+
+       scsiback_disconnect(info);
+       scsiback_release_translation_entry(info);
+
+       dev_set_drvdata(&dev->dev, NULL);
+
+       return 0;
+}
+
+static int scsiback_probe(struct xenbus_device *dev,
+                          const struct xenbus_device_id *id)
+{
+       int err;
+       unsigned val = 0;
+
+       struct vscsibk_info *info = kzalloc(sizeof(struct vscsibk_info),
+                                           GFP_KERNEL);
+
+       DPRINTK("%p %d\n", dev, dev->otherend_id);
+
+       if (!info) {
+               xenbus_dev_fatal(dev, -ENOMEM, "allocating backend structure");
+               return -ENOMEM;
+       }
+       info->dev = dev;
+       dev_set_drvdata(&dev->dev, info);
+
+       info->domid = dev->otherend_id;
+       spin_lock_init(&info->ring_lock);
+       atomic_set(&info->nr_unreplied_reqs, 0);
+       init_waitqueue_head(&info->wq);
+       init_waitqueue_head(&info->shutdown_wq);
+       init_waitqueue_head(&info->waiting_to_free);
+       info->dev = dev;
+       info->irq = 0;
+       info->feature = 0;      /*default not HOSTMODE.*/
+       INIT_LIST_HEAD(&info->v2p_entry_lists);
+       spin_lock_init(&info->v2p_lock);
+
+       err = xenbus_scanf(XBT_NIL, dev->nodename, "feature-host", "%d", &val);
+       if (XENBUS_EXIST_ERR(err))
+               val = 0;
+
+       if (val)
+               info->feature = VSCSI_TYPE_HOST;
+
+       err = xenbus_printf(XBT_NIL, dev->nodename, "feature-sg-grant", "%u",
+                           SG_ALL);
+       if (err)
+               xenbus_dev_error(dev, err, "writing feature-sg-grant");
+
+       err = xenbus_switch_state(dev, XenbusStateInitWait);
+       if (err)
+               goto fail;
+
+       return 0;
+
+fail:
+       pr_warn("xen-pvscsi: %s failed\n", __func__);
+       scsiback_remove(dev);
+
+       return err;
+}
+
+static char *scsiback_dump_proto_id(struct scsiback_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 u8 scsiback_get_fabric_proto_ident(struct se_portal_group *se_tpg)
+{
+       struct scsiback_tpg *tpg = container_of(se_tpg,
+                               struct scsiback_tpg, se_tpg);
+       struct scsiback_tport *tport = tpg->tport;
+
+       switch (tport->tport_proto_id) {
+       case SCSI_PROTOCOL_SAS:
+               return sas_get_fabric_proto_ident(se_tpg);
+       case SCSI_PROTOCOL_FCP:
+               return fc_get_fabric_proto_ident(se_tpg);
+       case SCSI_PROTOCOL_ISCSI:
+               return iscsi_get_fabric_proto_ident(se_tpg);
+       default:
+               pr_err("Unknown tport_proto_id: 0x%02x, using SAS emulation\n",
+                       tport->tport_proto_id);
+               break;
+       }
+
+       return sas_get_fabric_proto_ident(se_tpg);
+}
+
+static char *scsiback_get_fabric_wwn(struct se_portal_group *se_tpg)
+{
+       struct scsiback_tpg *tpg = container_of(se_tpg,
+                               struct scsiback_tpg, se_tpg);
+       struct scsiback_tport *tport = tpg->tport;
+
+       return &tport->tport_name[0];
+}
+
+static u16 scsiback_get_tag(struct se_portal_group *se_tpg)
+{
+       struct scsiback_tpg *tpg = container_of(se_tpg,
+                               struct scsiback_tpg, se_tpg);
+       return tpg->tport_tpgt;
+}
+
+static u32 scsiback_get_default_depth(struct se_portal_group *se_tpg)
+{
+       return 1;
+}
+
+static u32
+scsiback_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 scsiback_tpg *tpg = container_of(se_tpg,
+                               struct scsiback_tpg, se_tpg);
+       struct scsiback_tport *tport = tpg->tport;
+
+       switch (tport->tport_proto_id) {
+       case SCSI_PROTOCOL_SAS:
+               return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
+                                       format_code, buf);
+       case SCSI_PROTOCOL_FCP:
+               return fc_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
+                                       format_code, buf);
+       case SCSI_PROTOCOL_ISCSI:
+               return iscsi_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
+                                       format_code, buf);
+       default:
+               pr_err("Unknown tport_proto_id: 0x%02x, using SAS emulation\n",
+                       tport->tport_proto_id);
+               break;
+       }
+
+       return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
+                       format_code, buf);
+}
+
+static u32
+scsiback_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 scsiback_tpg *tpg = container_of(se_tpg,
+                               struct scsiback_tpg, se_tpg);
+       struct scsiback_tport *tport = tpg->tport;
+
+       switch (tport->tport_proto_id) {
+       case SCSI_PROTOCOL_SAS:
+               return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
+                                       format_code);
+       case SCSI_PROTOCOL_FCP:
+               return fc_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
+                                       format_code);
+       case SCSI_PROTOCOL_ISCSI:
+               return iscsi_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
+                                       format_code);
+       default:
+               pr_err("Unknown tport_proto_id: 0x%02x, using SAS emulation\n",
+                       tport->tport_proto_id);
+               break;
+       }
+
+       return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
+                       format_code);
+}
+
+static char *
+scsiback_parse_pr_out_transport_id(struct se_portal_group *se_tpg,
+                                   const char *buf,
+                                   u32 *out_tid_len,
+                                   char **port_nexus_ptr)
+{
+       struct scsiback_tpg *tpg = container_of(se_tpg,
+                               struct scsiback_tpg, se_tpg);
+       struct scsiback_tport *tport = tpg->tport;
+
+       switch (tport->tport_proto_id) {
+       case SCSI_PROTOCOL_SAS:
+               return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
+                                       port_nexus_ptr);
+       case SCSI_PROTOCOL_FCP:
+               return fc_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
+                                       port_nexus_ptr);
+       case SCSI_PROTOCOL_ISCSI:
+               return iscsi_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
+                                       port_nexus_ptr);
+       default:
+               pr_err("Unknown tport_proto_id: 0x%02x, using SAS emulation\n",
+                       tport->tport_proto_id);
+               break;
+       }
+
+       return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
+                       port_nexus_ptr);
+}
+
+static struct se_wwn *
+scsiback_make_tport(struct target_fabric_configfs *tf,
+                    struct config_group *group,
+                    const char *name)
+{
+       struct scsiback_tport *tport;
+       char *ptr;
+       u64 wwpn = 0;
+       int off = 0;
+
+       tport = kzalloc(sizeof(struct scsiback_tport), GFP_KERNEL);
+       if (!tport) {
+               pr_err("Unable to allocate struct scsiback_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) >= VSCSI_NAMELEN) {
+               pr_err("Emulated %s Address: %s, exceeds max: %d\n", name,
+                       scsiback_dump_proto_id(tport), VSCSI_NAMELEN);
+               kfree(tport);
+               return ERR_PTR(-EINVAL);
+       }
+       snprintf(&tport->tport_name[0], VSCSI_NAMELEN, "%s", &name[off]);
+
+       pr_debug("xen-pvscsi: Allocated emulated Target %s Address: %s\n",
+                scsiback_dump_proto_id(tport), name);
+
+       return &tport->tport_wwn;
+}
+
+static void scsiback_drop_tport(struct se_wwn *wwn)
+{
+       struct scsiback_tport *tport = container_of(wwn,
+                               struct scsiback_tport, tport_wwn);
+
+       pr_debug("xen-pvscsi: Deallocating emulated Target %s Address: %s\n",
+                scsiback_dump_proto_id(tport), tport->tport_name);
+
+       kfree(tport);
+}
+
+static struct se_node_acl *
+scsiback_alloc_fabric_acl(struct se_portal_group *se_tpg)
+{
+       struct scsiback_nacl *nacl;
+
+       nacl = kzalloc(sizeof(struct scsiback_nacl), GFP_KERNEL);
+       if (!nacl) {
+               pr_err("Unable to allocate struct scsiback_nacl\n");
+               return NULL;
+       }
+
+       return &nacl->se_node_acl;
+}
+
+static void
+scsiback_release_fabric_acl(struct se_portal_group *se_tpg,
+                            struct se_node_acl *se_nacl)
+{
+       struct scsiback_nacl *nacl = container_of(se_nacl,
+                       struct scsiback_nacl, se_node_acl);
+       kfree(nacl);
+}
+
+static u32 scsiback_tpg_get_inst_index(struct se_portal_group *se_tpg)
+{
+       return 1;
+}
+
+static struct se_node_acl *
+scsiback_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 scsiback_nacl *nacl;
+       u64 wwpn = 0;
+       u32 nexus_depth;
+
+       se_nacl_new = scsiback_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)) {
+               scsiback_release_fabric_acl(se_tpg, se_nacl_new);
+               return se_nacl;
+       }
+       /*
+        * Locate our struct scsiback_nacl and set the FC Nport WWPN
+        */
+       nacl = container_of(se_nacl, struct scsiback_nacl, se_node_acl);
+       nacl->iport_wwpn = wwpn;
+
+       return se_nacl;
+}
+
+static void scsiback_drop_nodeacl(struct se_node_acl *se_acl)
+{
+       struct scsiback_nacl *nacl = container_of(se_acl,
+                               struct scsiback_nacl, se_node_acl);
+       core_tpg_del_initiator_node_acl(se_acl->se_tpg, se_acl, 1);
+       kfree(nacl);
+}
+
+static int scsiback_check_stop_free(struct se_cmd *se_cmd)
+{
+       return target_put_sess_cmd(se_cmd->se_sess, se_cmd);
+}
+
+static void scsiback_release_cmd(struct se_cmd *se_cmd)
+{
+}
+
+static int scsiback_shutdown_session(struct se_session *se_sess)
+{
+       return 0;
+}
+
+static void scsiback_close_session(struct se_session *se_sess)
+{
+}
+
+static u32 scsiback_sess_get_index(struct se_session *se_sess)
+{
+       return 0;
+}
+
+static int scsiback_write_pending(struct se_cmd *se_cmd)
+{
+       /* Go ahead and process the write immediately */
+       target_execute_cmd(se_cmd);
+
+       return 0;
+}
+
+static int scsiback_write_pending_status(struct se_cmd *se_cmd)
+{
+       return 0;
+}
+
+static void scsiback_set_default_node_attrs(struct se_node_acl *nacl)
+{
+}
+
+static u32 scsiback_get_task_tag(struct se_cmd *se_cmd)
+{
+       return 0;
+}
+
+static int scsiback_get_cmd_state(struct se_cmd *se_cmd)
+{
+       return 0;
+}
+
+static int scsiback_queue_data_in(struct se_cmd *se_cmd)
+{
+       struct vscsibk_pend *pending_req = container_of(se_cmd,
+                               struct vscsibk_pend, se_cmd);
+
+       pending_req->result = SAM_STAT_GOOD;
+       scsiback_cmd_done(pending_req);
+       return 0;
+}
+
+static int scsiback_queue_status(struct se_cmd *se_cmd)
+{
+       struct vscsibk_pend *pending_req = container_of(se_cmd,
+                               struct vscsibk_pend, se_cmd);
+
+       if (se_cmd->sense_buffer &&
+           ((se_cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) ||
+            (se_cmd->se_cmd_flags & SCF_EMULATED_TASK_SENSE)))
+               pending_req->result = (DRIVER_SENSE << 24) |
+                                     SAM_STAT_CHECK_CONDITION;
+       else
+               pending_req->result = se_cmd->scsi_status;
+
+       scsiback_cmd_done(pending_req);
+       return 0;
+}
+
+static void scsiback_queue_tm_rsp(struct se_cmd *se_cmd)
+{
+       struct se_tmr_req *se_tmr = se_cmd->se_tmr_req;
+       struct scsiback_tmr *tmr = se_tmr->fabric_tmr_ptr;
+
+       atomic_set(&tmr->tmr_complete, 1);
+       wake_up(&tmr->tmr_wait);
+}
+
+static void scsiback_aborted_task(struct se_cmd *se_cmd)
+{
+       struct se_tmr_req *se_tmr = se_cmd->se_tmr_req;
+       struct scsiback_tmr *tmr = se_tmr->fabric_tmr_ptr;
+
+       atomic_set(&tmr->tmr_complete, 1);
+       wake_up(&tmr->tmr_wait);
+}
+
+static ssize_t scsiback_tpg_param_show_alias(struct se_portal_group *se_tpg,
+                                            char *page)
+{
+       struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
+                                               se_tpg);
+       ssize_t rb;
+
+       mutex_lock(&tpg->tv_tpg_mutex);
+       rb = snprintf(page, PAGE_SIZE, "%s\n", tpg->param_alias);
+       mutex_unlock(&tpg->tv_tpg_mutex);
+
+       return rb;
+}
+
+static ssize_t scsiback_tpg_param_store_alias(struct se_portal_group *se_tpg,
+                                             const char *page, size_t count)
+{
+       struct scsiback_tpg *tpg = container_of(se_tpg, struct scsiback_tpg,
+                                               se_tpg);
+       int len;
+
+       if (strlen(page) >= VSCSI_NAMELEN) {
+               pr_err("param alias: %s, exceeds max: %d\n", page,
+                       VSCSI_NAMELEN);
+               return -EINVAL;
+       }
+
+       mutex_lock(&tpg->tv_tpg_mutex);
+       len = snprintf(tpg->param_alias, VSCSI_NAMELEN, "%s", page);
+       if (tpg->param_alias[len - 1] == '\n')
+               tpg->param_alias[len - 1] = '\0';
+       mutex_unlock(&tpg->tv_tpg_mutex);
+
+       return count;
+}
+
+TF_TPG_PARAM_ATTR(scsiback, alias, S_IRUGO | S_IWUSR);
+
+static struct configfs_attribute *scsiback_param_attrs[] = {
+       &scsiback_tpg_param_alias.attr,
+       NULL,
+};
+
+static int scsiback_make_nexus(struct scsiback_tpg *tpg,
+                               const char *name)
+{
+       struct se_portal_group *se_tpg;
+       struct se_session *se_sess;
+       struct scsiback_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;
+       }
+       se_tpg = &tpg->se_tpg;
+
+       tv_nexus = kzalloc(sizeof(struct scsiback_nexus), GFP_KERNEL);
+       if (!tv_nexus) {
+               mutex_unlock(&tpg->tv_tpg_mutex);
+               pr_err("Unable to allocate struct scsiback_nexus\n");
+               return -ENOMEM;
+       }
+       /*
+        *  Initialize the struct se_session pointer
+        */
+       tv_nexus->tvn_se_sess = transport_init_session(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;
+       /*
+        * Since we are running in 'demo mode' this call with generate a
+        * struct se_node_acl for the scsiback 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\n",
+                        name);
+               goto out;
+       }
+       /*
+        * Now register the TCM pvscsi 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:
+       transport_free_session(se_sess);
+       kfree(tv_nexus);
+       return -ENOMEM;
+}
+
+static int scsiback_drop_nexus(struct scsiback_tpg *tpg)
+{
+       struct se_session *se_sess;
+       struct scsiback_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 xen-pvscsi I_T Nexus with active TPG 
port count: %d\n",
+                       tpg->tv_tpg_port_count);
+               return -EBUSY;
+       }
+
+       if (tpg->tv_tpg_fe_count != 0) {
+               mutex_unlock(&tpg->tv_tpg_mutex);
+               pr_err("Unable to remove xen-pvscsi I_T Nexus with active TPG 
frontend count: %d\n",
+                       tpg->tv_tpg_fe_count);
+               return -EBUSY;
+       }
+
+       pr_debug("xen-pvscsi: Removing I_T Nexus to emulated %s Initiator Port: 
%s\n",
+               scsiback_dump_proto_id(tpg->tport),
+               tv_nexus->tvn_se_sess->se_node_acl->initiatorname);
+
+       /*
+        * Release the SCSI I_T Nexus to the emulated xen-pvscsi 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 scsiback_tpg_show_nexus(struct se_portal_group *se_tpg,
+                                       char *page)
+{
+       struct scsiback_tpg *tpg = container_of(se_tpg,
+                               struct scsiback_tpg, se_tpg);
+       struct scsiback_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 scsiback_tpg_store_nexus(struct se_portal_group *se_tpg,
+                                        const char *page,
+                                        size_t count)
+{
+       struct scsiback_tpg *tpg = container_of(se_tpg,
+                               struct scsiback_tpg, se_tpg);
+       struct scsiback_tport *tport_wwn = tpg->tport;
+       unsigned char i_port[VSCSI_NAMELEN], *ptr, *port_ptr;
+       int ret;
+       /*
+        * Shutdown the active I_T nexus if 'NULL' is passed..
+        */
+       if (!strncmp(page, "NULL", 4)) {
+               ret = scsiback_drop_nexus(tpg);
+               return (!ret) ? count : ret;
+       }
+       /*
+        * Otherwise make sure the passed virtual Initiator port WWN matches
+        * the fabric protocol_id set in scsiback_make_tport(), and call
+        * scsiback_make_nexus().
+        */
+       if (strlen(page) >= VSCSI_NAMELEN) {
+               pr_err("Emulated NAA Sas Address: %s, exceeds max: %d\n",
+                       page, VSCSI_NAMELEN);
+               return -EINVAL;
+       }
+       snprintf(&i_port[0], VSCSI_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, scsiback_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, scsiback_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, scsiback_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 = scsiback_make_nexus(tpg, port_ptr);
+       if (ret < 0)
+               return ret;
+
+       return count;
+}
+
+TF_TPG_BASE_ATTR(scsiback, nexus, S_IRUGO | S_IWUSR);
+
+static struct configfs_attribute *scsiback_tpg_attrs[] = {
+       &scsiback_tpg_nexus.attr,
+       NULL,
+};
+
+static ssize_t
+scsiback_wwn_show_attr_version(struct target_fabric_configfs *tf,
+                               char *page)
+{
+       return sprintf(page, "xen-pvscsi fabric module %s on %s/%s on "
+               UTS_RELEASE"\n",
+               VSCSI_VERSION, utsname()->sysname, utsname()->machine);
+}
+
+TF_WWN_ATTR_RO(scsiback, version);
+
+static struct configfs_attribute *scsiback_wwn_attrs[] = {
+       &scsiback_wwn_version.attr,
+       NULL,
+};
+
+static char *scsiback_get_fabric_name(void)
+{
+       return "xen-pvscsi";
+}
+
+static int scsiback_port_link(struct se_portal_group *se_tpg,
+                              struct se_lun *lun)
+{
+       struct scsiback_tpg *tpg = container_of(se_tpg,
+                               struct scsiback_tpg, se_tpg);
+
+       mutex_lock(&scsiback_mutex);
+
+       mutex_lock(&tpg->tv_tpg_mutex);
+       tpg->tv_tpg_port_count++;
+       mutex_unlock(&tpg->tv_tpg_mutex);
+
+       mutex_unlock(&scsiback_mutex);
+
+       return 0;
+}
+
+static void scsiback_port_unlink(struct se_portal_group *se_tpg,
+                                 struct se_lun *lun)
+{
+       struct scsiback_tpg *tpg = container_of(se_tpg,
+                               struct scsiback_tpg, se_tpg);
+
+       mutex_lock(&scsiback_mutex);
+
+       mutex_lock(&tpg->tv_tpg_mutex);
+       tpg->tv_tpg_port_count--;
+       mutex_unlock(&tpg->tv_tpg_mutex);
+
+       mutex_unlock(&scsiback_mutex);
+}
+
+static struct se_portal_group *
+scsiback_make_tpg(struct se_wwn *wwn,
+                  struct config_group *group,
+                  const char *name)
+{
+       struct scsiback_tport *tport = container_of(wwn,
+                       struct scsiback_tport, tport_wwn);
+
+       struct scsiback_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 scsiback_tpg), GFP_KERNEL);
+       if (!tpg) {
+               pr_err("Unable to allocate struct scsiback_tpg");
+               return ERR_PTR(-ENOMEM);
+       }
+       mutex_init(&tpg->tv_tpg_mutex);
+       INIT_LIST_HEAD(&tpg->tv_tpg_list);
+       INIT_LIST_HEAD(&tpg->info_list);
+       tpg->tport = tport;
+       tpg->tport_tpgt = tpgt;
+
+       ret = core_tpg_register(&scsiback_fabric_configfs->tf_ops, wwn,
+                               &tpg->se_tpg, tpg, TRANSPORT_TPG_TYPE_NORMAL);
+       if (ret < 0) {
+               kfree(tpg);
+               return NULL;
+       }
+       mutex_lock(&scsiback_mutex);
+       list_add_tail(&tpg->tv_tpg_list, &scsiback_list);
+       mutex_unlock(&scsiback_mutex);
+
+       return &tpg->se_tpg;
+}
+
+static void scsiback_drop_tpg(struct se_portal_group *se_tpg)
+{
+       struct scsiback_tpg *tpg = container_of(se_tpg,
+                               struct scsiback_tpg, se_tpg);
+
+       mutex_lock(&scsiback_mutex);
+       list_del(&tpg->tv_tpg_list);
+       mutex_unlock(&scsiback_mutex);
+       /*
+        * Release the virtual I_T Nexus for this xen-pvscsi TPG
+        */
+       scsiback_drop_nexus(tpg);
+       /*
+        * Deregister the se_tpg from TCM..
+        */
+       core_tpg_deregister(se_tpg);
+       kfree(tpg);
+}
+
+static int scsiback_check_true(struct se_portal_group *se_tpg)
+{
+       return 1;
+}
+
+static int scsiback_check_false(struct se_portal_group *se_tpg)
+{
+       return 0;
+}
+
+static struct target_core_fabric_ops scsiback_ops = {
+       .get_fabric_name                = scsiback_get_fabric_name,
+       .get_fabric_proto_ident         = scsiback_get_fabric_proto_ident,
+       .tpg_get_wwn                    = scsiback_get_fabric_wwn,
+       .tpg_get_tag                    = scsiback_get_tag,
+       .tpg_get_default_depth          = scsiback_get_default_depth,
+       .tpg_get_pr_transport_id        = scsiback_get_pr_transport_id,
+       .tpg_get_pr_transport_id_len    = scsiback_get_pr_transport_id_len,
+       .tpg_parse_pr_out_transport_id  = scsiback_parse_pr_out_transport_id,
+       .tpg_check_demo_mode            = scsiback_check_true,
+       .tpg_check_demo_mode_cache      = scsiback_check_true,
+       .tpg_check_demo_mode_write_protect = scsiback_check_false,
+       .tpg_check_prod_mode_write_protect = scsiback_check_false,
+       .tpg_alloc_fabric_acl           = scsiback_alloc_fabric_acl,
+       .tpg_release_fabric_acl         = scsiback_release_fabric_acl,
+       .tpg_get_inst_index             = scsiback_tpg_get_inst_index,
+       .check_stop_free                = scsiback_check_stop_free,
+       .release_cmd                    = scsiback_release_cmd,
+       .put_session                    = NULL,
+       .shutdown_session               = scsiback_shutdown_session,
+       .close_session                  = scsiback_close_session,
+       .sess_get_index                 = scsiback_sess_get_index,
+       .sess_get_initiator_sid         = NULL,
+       .write_pending                  = scsiback_write_pending,
+       .write_pending_status           = scsiback_write_pending_status,
+       .set_default_node_attributes    = scsiback_set_default_node_attrs,
+       .get_task_tag                   = scsiback_get_task_tag,
+       .get_cmd_state                  = scsiback_get_cmd_state,
+       .queue_data_in                  = scsiback_queue_data_in,
+       .queue_status                   = scsiback_queue_status,
+       .queue_tm_rsp                   = scsiback_queue_tm_rsp,
+       .aborted_task                   = scsiback_aborted_task,
+       /*
+        * Setup callers for generic logic in target_core_fabric_configfs.c
+        */
+       .fabric_make_wwn                = scsiback_make_tport,
+       .fabric_drop_wwn                = scsiback_drop_tport,
+       .fabric_make_tpg                = scsiback_make_tpg,
+       .fabric_drop_tpg                = scsiback_drop_tpg,
+       .fabric_post_link               = scsiback_port_link,
+       .fabric_pre_unlink              = scsiback_port_unlink,
+       .fabric_make_np                 = NULL,
+       .fabric_drop_np                 = NULL,
+       .fabric_make_nodeacl            = scsiback_make_nodeacl,
+       .fabric_drop_nodeacl            = scsiback_drop_nodeacl,
+};
+
+static int scsiback_register_configfs(void)
+{
+       struct target_fabric_configfs *fabric;
+       int ret;
+
+       pr_debug("xen-pvscsi: fabric module %s on %s/%s on "UTS_RELEASE"\n",
+                VSCSI_VERSION, utsname()->sysname, utsname()->machine);
+       /*
+        * Register the top level struct config_item_type with TCM core
+        */
+       fabric = target_fabric_configfs_init(THIS_MODULE, "xen-pvscsi");
+       if (IS_ERR(fabric)) {
+               pr_err("target_fabric_configfs_init() failed\n");
+               return PTR_ERR(fabric);
+       }
+       /*
+        * Setup fabric->tf_ops from our local scsiback_ops
+        */
+       fabric->tf_ops = scsiback_ops;
+       /*
+        * Setup default attribute lists for various fabric->tf_cit_tmpl
+        */
+       fabric->tf_cit_tmpl.tfc_wwn_cit.ct_attrs = scsiback_wwn_attrs;
+       fabric->tf_cit_tmpl.tfc_tpg_base_cit.ct_attrs = scsiback_tpg_attrs;
+       fabric->tf_cit_tmpl.tfc_tpg_attrib_cit.ct_attrs = NULL;
+       fabric->tf_cit_tmpl.tfc_tpg_param_cit.ct_attrs = scsiback_param_attrs;
+       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("xen-pvscsi: target_fabric_configfs_register() 
failed\n");
+               return ret;
+       }
+       /*
+        * Setup our local pointer to *fabric
+        */
+       scsiback_fabric_configfs = fabric;
+       pr_debug("xen-pvscsi: Set fabric -> scsiback_fabric_configfs\n");
+       return 0;
+};
+
+static void scsiback_deregister_configfs(void)
+{
+       if (!scsiback_fabric_configfs)
+               return;
+
+       target_fabric_configfs_deregister(scsiback_fabric_configfs);
+       scsiback_fabric_configfs = NULL;
+       pr_debug("xen-pvscsi: Cleared scsiback_fabric_configfs\n");
+};
+
+static const struct xenbus_device_id scsiback_ids[] = {
+       { "vscsi" },
+       { "" }
+};
+
+static DEFINE_XENBUS_DRIVER(scsiback, ,
+       .probe                  = scsiback_probe,
+       .remove                 = scsiback_remove,
+       .otherend_changed       = scsiback_frontend_changed
+);
+
+static void scsiback_init_pend(void *p)
+{
+       struct vscsibk_pend *pend = p;
+       int i;
+
+       memset(pend, 0, sizeof(*pend));
+       for (i = 0; i < VSCSI_MAX_GRANTS; i++)
+               pend->grant_handles[i] = SCSIBACK_INVALID_HANDLE;
+}
+
+static int __init scsiback_init(void)
+{
+       int ret;
+
+       if (!xen_domain())
+               return -ENODEV;
+
+       scsiback_cachep = kmem_cache_create("vscsiif_cache",
+               sizeof(struct vscsibk_pend), 0, 0, scsiback_init_pend);
+       if (!scsiback_cachep) {
+               pr_err("xen-pvscsi: can't init scsi cache\n");
+               return -ENOMEM;
+       }
+
+       ret = xenbus_register_backend(&scsiback_driver);
+       if (ret)
+               goto out_cache_destroy;
+
+       ret = scsiback_register_configfs();
+       if (ret)
+               goto out_unregister_xenbus;
+
+       return 0;
+
+out_unregister_xenbus:
+       xenbus_unregister_driver(&scsiback_driver);
+out_cache_destroy:
+       kmem_cache_destroy(scsiback_cachep);
+       pr_err("xen-pvscsi: %s: error %d\n", __func__, ret);
+       return ret;
+}
+
+static void __exit scsiback_exit(void)
+{
+       struct page *page;
+
+       while (free_pages_num) {
+               if (get_free_page(&page))
+                       BUG();
+               free_xenballooned_pages(1, &page);
+       }
+       scsiback_deregister_configfs();
+       xenbus_unregister_driver(&scsiback_driver);
+       kmem_cache_destroy(scsiback_cachep);
+}
+
+module_init(scsiback_init);
+module_exit(scsiback_exit);
+
+MODULE_DESCRIPTION("Xen SCSI backend driver");
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_ALIAS("xen-backend:vscsi");
-- 
1.8.4.5


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