static void
simscsi_sg_readwrite (struct scsi_cmnd *sc, int mode, unsigned long offset)
{
	int i;
	struct scatterlist *sl;
	struct disk_stat stat;
	struct disk_req req;

	stat.fd = desc[sc->device->id];

	scsi_for_each_sg(sc, sl, scsi_sg_count(sc), i) {
		req.addr = __pa(sg_virt(sl));
		req.len  = sl->length;
		if (DBG)
			printk("simscsi_sg_%s @ %lx (off %lx) use_sg=%d len=%d\n",
			       mode == SSC_READ ? "read":"write", req.addr, offset,
			       scsi_sg_count(sc) - i, sl->length);
		ia64_ssc(stat.fd, 1, __pa(&req), offset, mode);
		ia64_ssc(__pa(&stat), 0, 0, 0, SSC_WAIT_COMPLETION);

		/* should not happen in our case */
		if (stat.count != req.len) {
			sc->result = DID_ERROR << 16;
			return;
		}
		offset +=  sl->length;
	}

static int srp_direct_data(struct scsi_cmnd *sc, struct srp_direct_buf *md,
                           enum dma_data_direction dir, srp_rdma_t rdma_io,
                           int dma_map, int ext_desc)
{
    struct iu_entry *iue = NULL;
    struct scatterlist *sg = NULL;
    int err, nsg = 0, len;

    if (dma_map) {
        iue = (struct iu_entry *) sc->SCp.ptr;
        sg = scsi_sglist(sc);

        dprintk("%p %u %u %d\n", iue, scsi_bufflen(sc),
                md->len, scsi_sg_count(sc));

        nsg = dma_map_sg(iue->target->dev, sg, scsi_sg_count(sc),
                         DMA_BIDIRECTIONAL);
        if (!nsg) {
            printk("fail to map %p %d\n", iue, scsi_sg_count(sc));
            return 0;
        }
        len = min(scsi_bufflen(sc), md->len);
    } else
        len = md->len;

    err = rdma_io(sc, sg, nsg, md, 1, dir, len);

    if (dma_map)
        dma_unmap_sg(iue->target->dev, sg, nsg, DMA_BIDIRECTIONAL);

    return err;
}

/**
 * scsi_dma_unmap - unmap command's sg lists mapped by scsi_dma_map
 * @cmd:	scsi command
 */
void scsi_dma_unmap(struct scsi_cmnd *cmd)
{
	if (scsi_sg_count(cmd)) {
		struct device *dev = cmd->device->host->shost_gendev.parent;

		dma_unmap_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),
			     cmd->sc_data_direction);
	}
}

/**
 * iser_send_command - send command PDU
 */
int iser_send_command(struct iscsi_conn *conn,
		      struct iscsi_task *task)
{
	struct iscsi_iser_conn *iser_conn = conn->dd_data;
	struct iscsi_iser_task *iser_task = task->dd_data;
	unsigned long edtl;
	int err;
	struct iser_data_buf *data_buf;
	struct iscsi_cmd *hdr =  (struct iscsi_cmd *)task->hdr;
	struct scsi_cmnd *sc  =  task->sc;
	struct iser_tx_desc *tx_desc = &iser_task->desc;

	edtl = ntohl(hdr->data_length);

	/* build the tx desc regd header and add it to the tx desc dto */
	tx_desc->type = ISCSI_TX_SCSI_COMMAND;
	iser_create_send_desc(iser_conn->ib_conn, tx_desc);

	if (hdr->flags & ISCSI_FLAG_CMD_READ)
		data_buf = &iser_task->data[ISER_DIR_IN];
	else
		data_buf = &iser_task->data[ISER_DIR_OUT];

	if (scsi_sg_count(sc)) { /* using a scatter list */
		data_buf->buf  = scsi_sglist(sc);
		data_buf->size = scsi_sg_count(sc);
	}

	data_buf->data_len = scsi_bufflen(sc);

	if (hdr->flags & ISCSI_FLAG_CMD_READ) {
		err = iser_prepare_read_cmd(task, edtl);
		if (err)
			goto send_command_error;
	}
	if (hdr->flags & ISCSI_FLAG_CMD_WRITE) {
		err = iser_prepare_write_cmd(task,
					     task->imm_count,
				             task->imm_count +
					     task->unsol_r2t.data_length,
					     edtl);
		if (err)
			goto send_command_error;
	}

	iser_task->status = ISER_TASK_STATUS_STARTED;

	err = iser_post_send(iser_conn->ib_conn, tx_desc);
	if (!err)
		return 0;

send_command_error:
	iser_err("conn %p failed task->itt %d err %d\n",conn, task->itt, err);
	return err;
}

/**
 * scsi_dma_map - perform DMA mapping against command's sg lists
 * @cmd:	scsi command
 *
 * Returns the number of sg lists actually used, zero if the sg lists
 * is NULL, or -ENOMEM if the mapping failed.
 */
int scsi_dma_map(struct scsi_cmnd *cmd)
{
	int nseg = 0;

	if (scsi_sg_count(cmd)) {
		struct device *dev = cmd->device->host->shost_gendev.parent;

		nseg = dma_map_sg(dev, scsi_sglist(cmd), scsi_sg_count(cmd),
				  cmd->sc_data_direction);
		if (unlikely(!nseg))
			return -ENOMEM;
	}
	return nseg;
}

/*
 * copy data from device into scatter/gather buffer
 */
static int fill_from_dev_buffer(struct scsi_cmnd *cmd, const void *buf)
{
	int k, req_len, act_len, len, active;
	void *kaddr;
	struct scatterlist *sgpnt;
	unsigned int buflen;

	buflen = scsi_bufflen(cmd);
	if (!buflen)
		return 0;

	if (!scsi_sglist(cmd))
		return -1;

	active = 1;
	req_len = act_len = 0;
	scsi_for_each_sg(cmd, sgpnt, scsi_sg_count(cmd), k) {
		if (active) {
			kaddr = kmap_atomic(sg_page(sgpnt), KM_IRQ0);
			len = sgpnt->length;
			if ((req_len + len) > buflen) {
				active = 0;
				len = buflen - req_len;
			}
			memcpy(kaddr + sgpnt->offset, buf + req_len, len);
			flush_kernel_dcache_page(sg_page(sgpnt));
			kunmap_atomic(kaddr, KM_IRQ0);
			act_len += len;
		}
		req_len += sgpnt->length;
	}
	scsi_set_resid(cmd, req_len - act_len);
	return 0;
}

/*
 * copy data from scatter/gather into device's buffer
 */
static int fetch_to_dev_buffer(struct scsi_cmnd *cmd, void *buf)
{
	int k, req_len, len, fin;
	void *kaddr;
	struct scatterlist *sgpnt;
	unsigned int buflen;

	buflen = scsi_bufflen(cmd);
	if (!buflen)
		return 0;

	if (!scsi_sglist(cmd))
		return -1;

	req_len = fin = 0;
	scsi_for_each_sg(cmd, sgpnt, scsi_sg_count(cmd), k) {
		kaddr = kmap_atomic(sg_page(sgpnt), KM_IRQ0);
		len = sgpnt->length;
		if ((req_len + len) > buflen) {
			len = buflen - req_len;
			fin = 1;
		}
		memcpy(buf + req_len, kaddr + sgpnt->offset, len);
		kunmap_atomic(kaddr, KM_IRQ0);
		if (fin)
			return req_len + len;
		req_len += sgpnt->length;
	}

/**************************************************************************
 *   qla2x00_print_scsi_cmd
 *	 Dumps out info about the scsi cmd and srb.
 *   Input
 *	 cmd : struct scsi_cmnd
 **************************************************************************/
void
qla2x00_print_scsi_cmd(struct scsi_cmnd * cmd)
{
	int i;
	struct scsi_qla_host *ha;
	srb_t *sp;

	ha = shost_priv(cmd->device->host);

	sp = (srb_t *) cmd->SCp.ptr;
	printk("SCSI Command @=0x%p, Handle=0x%p\n", cmd, cmd->host_scribble);
	printk("  chan=0x%02x, target=0x%02x, lun=0x%02x, cmd_len=0x%02x\n",
	    cmd->device->channel, cmd->device->id, cmd->device->lun,
	    cmd->cmd_len);
	printk(" CDB: ");
	for (i = 0; i < cmd->cmd_len; i++) {
		printk("0x%02x ", cmd->cmnd[i]);
	}
	printk("\n  seg_cnt=%d, allowed=%d, retries=%d\n",
	       scsi_sg_count(cmd), cmd->allowed, cmd->retries);
	printk("  request buffer=0x%p, request buffer len=0x%x\n",
	       scsi_sglist(cmd), scsi_bufflen(cmd));
	printk("  tag=%d, transfersize=0x%x\n",
	    cmd->tag, cmd->transfersize);
	printk("  serial_number=%lx, SP=%p\n", cmd->serial_number, sp);
	printk("  data direction=%d\n", cmd->sc_data_direction);

	if (!sp)
		return;

	printk("  sp flags=0x%x\n", sp->flags);
}

static struct sas_task *sas_create_task(struct scsi_cmnd *cmd,
					       struct domain_device *dev,
					       gfp_t gfp_flags)
{
	struct sas_task *task = sas_alloc_task(gfp_flags);
	struct scsi_lun lun;

	if (!task)
		return NULL;

	task->uldd_task = cmd;
	ASSIGN_SAS_TASK(cmd, task);

	task->dev = dev;
	task->task_proto = task->dev->tproto; /* BUG_ON(!SSP) */

	task->ssp_task.retry_count = 1;
	int_to_scsilun(cmd->device->lun, &lun);
	memcpy(task->ssp_task.LUN, &lun.scsi_lun, 8);
	task->ssp_task.task_attr = TASK_ATTR_SIMPLE;
	memcpy(task->ssp_task.cdb, cmd->cmnd, 16);

	task->scatter = scsi_sglist(cmd);
	task->num_scatter = scsi_sg_count(cmd);
	task->total_xfer_len = scsi_bufflen(cmd);
	task->data_dir = cmd->sc_data_direction;

	task->task_done = sas_scsi_task_done;

	return task;
}

static void pvscsi_unmap_buffers(const struct pvscsi_adapter *adapter,
				 struct pvscsi_ctx *ctx)
{
	struct scsi_cmnd *cmd;
	unsigned bufflen;

	cmd = ctx->cmd;
	bufflen = scsi_bufflen(cmd);

	if (bufflen != 0) {
		unsigned count = scsi_sg_count(cmd);

		if (count != 0) {
			scsi_dma_unmap(cmd);
			if (ctx->sglPA) {
				pci_unmap_single(adapter->dev, ctx->sglPA,
						 SGL_SIZE, PCI_DMA_TODEVICE);
				ctx->sglPA = 0;
			}
		} else
			pci_unmap_single(adapter->dev, ctx->dataPA, bufflen,
					 cmd->sc_data_direction);
	}
	if (cmd->sense_buffer)
		pci_unmap_single(adapter->dev, ctx->sensePA,
				 SCSI_SENSE_BUFFERSIZE, PCI_DMA_FROMDEVICE);
}

static int mac53c94_queue_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *))
{
	struct fsc_state *state;

#if 0
	if (cmd->sc_data_direction == DMA_TO_DEVICE) {
		int i;
		printk(KERN_DEBUG "mac53c94_queue %p: command is", cmd);
		for (i = 0; i < cmd->cmd_len; ++i)
			printk(KERN_CONT " %.2x", cmd->cmnd[i]);
		printk(KERN_CONT "\n");
		printk(KERN_DEBUG "use_sg=%d request_bufflen=%d request_buffer=%p\n",
		       scsi_sg_count(cmd), scsi_bufflen(cmd), scsi_sglist(cmd));
	}
#endif

	cmd->scsi_done = done;
	cmd->host_scribble = NULL;

	state = (struct fsc_state *) cmd->device->host->hostdata;

	if (state->request_q == NULL)
		state->request_q = cmd;
	else
		state->request_qtail->host_scribble = (void *) cmd;
	state->request_qtail = cmd;

	if (state->phase == idle)
		mac53c94_start(state);

	return 0;
}

static void tcm_loop_submission_work(struct work_struct *work)
{
	struct tcm_loop_cmd *tl_cmd =
		container_of(work, struct tcm_loop_cmd, work);
	struct se_cmd *se_cmd = &tl_cmd->tl_se_cmd;
	struct scsi_cmnd *sc = tl_cmd->sc;
	struct tcm_loop_nexus *tl_nexus;
	struct tcm_loop_hba *tl_hba;
	struct tcm_loop_tpg *tl_tpg;
	struct scatterlist *sgl_bidi = NULL;
	u32 sgl_bidi_count = 0;
	int rc;

	tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
	tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];

	/*
	 * Ensure that this tl_tpg reference from the incoming sc->device->id
	 * has already been configured via tcm_loop_make_naa_tpg().
	 */
	if (!tl_tpg->tl_hba) {
		set_host_byte(sc, DID_NO_CONNECT);
		goto out_done;
	}
	if (tl_tpg->tl_transport_status == TCM_TRANSPORT_OFFLINE) {
		set_host_byte(sc, DID_TRANSPORT_DISRUPTED);
		goto out_done;
	}
	tl_nexus = tl_hba->tl_nexus;
	if (!tl_nexus) {
		scmd_printk(KERN_ERR, sc, "TCM_Loop I_T Nexus"
				" does not exist\n");
		set_host_byte(sc, DID_ERROR);
		goto out_done;
	}
	if (scsi_bidi_cmnd(sc)) {
		struct scsi_data_buffer *sdb = scsi_in(sc);

		sgl_bidi = sdb->table.sgl;
		sgl_bidi_count = sdb->table.nents;
		se_cmd->se_cmd_flags |= SCF_BIDI;

	}
	rc = target_submit_cmd_map_sgls(se_cmd, tl_nexus->se_sess, sc->cmnd,
			&tl_cmd->tl_sense_buf[0], tl_cmd->sc->device->lun,
			scsi_bufflen(sc), tcm_loop_sam_attr(sc),
			sc->sc_data_direction, 0,
			scsi_sglist(sc), scsi_sg_count(sc),
			sgl_bidi, sgl_bidi_count);
	if (rc < 0) {
		set_host_byte(sc, DID_NO_CONNECT);
		goto out_done;
	}
	return;

out_done:
	sc->scsi_done(sc);
	return;
}

/**
 * zfcp_qdio_sbals_from_scsicmnd - fill SBALs from scsi command
 * @fsf_req: request to be processed
 * @sbtype: SBALE flags
 * @scsi_cmnd: either scatter-gather list or buffer contained herein is used
 *	to fill SBALs
 */
int
zfcp_qdio_sbals_from_scsicmnd(struct zfcp_fsf_req *fsf_req,
			      unsigned long sbtype, struct scsi_cmnd *scsi_cmnd)
{
	return zfcp_qdio_sbals_from_sg(fsf_req,	sbtype, scsi_sglist(scsi_cmnd),
				       scsi_sg_count(scsi_cmnd),
				       ZFCP_MAX_SBALS_PER_REQ);
}

//----- usb_stor_bulk_srb() ---------------------
int usb_stor_bulk_srb(struct us_data* us, unsigned int pipe, struct scsi_cmnd* srb)
{
	unsigned int partial;
	int result = usb_stor_bulk_transfer_sglist(us, pipe, scsi_sglist(srb),
				      scsi_sg_count(srb), scsi_bufflen(srb),
				      &partial);

	scsi_set_resid(srb, scsi_bufflen(srb) - partial);
	return result;
}

/**
 * scsi_dma_map - perform DMA mapping against command's sg lists
 * @cmd:	scsi command
 *
 * Returns the number of sg lists actually used, zero if the sg lists
 * is NULL, or -ENOMEM if the mapping failed.
 */
int scsi_dma_map(struct scsi_cmnd *cmd)
{
	int nseg = 0;
	struct dma_attrs *attrs = &scsi_direct_attrs;

	if (scsi_sg_count(cmd)) {
		struct device *dev = cmd->device->host->dma_dev;

		if (dma_get_attr(DMA_ATTR_SKIP_CPU_SYNC, attrs))
			attrs = (cmd->request->cmd_flags & REQ_KERNEL) ?
				&scsi_direct_attrs : NULL;
		nseg = dma_map_sg_attr(dev, scsi_sglist(cmd),
				scsi_sg_count(cmd),
				cmd->sc_data_direction, attrs);
		if (unlikely(!nseg))
			return -ENOMEM;
	}
	return nseg;
}

static void sd_zbc_report_zones_complete(struct scsi_cmnd *scmd,
					 unsigned int good_bytes)
{
	struct request *rq = scmd->request;
	struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
	struct sg_mapping_iter miter;
	struct blk_zone_report_hdr hdr;
	struct blk_zone zone;
	unsigned int offset, bytes = 0;
	unsigned long flags;
	u8 *buf;

	if (good_bytes < 64)
		return;

	memset(&hdr, 0, sizeof(struct blk_zone_report_hdr));

	sg_miter_start(&miter, scsi_sglist(scmd), scsi_sg_count(scmd),
		       SG_MITER_TO_SG | SG_MITER_ATOMIC);

	local_irq_save(flags);
	while (sg_miter_next(&miter) && bytes < good_bytes) {

		buf = miter.addr;
		offset = 0;

		if (bytes == 0) {
			/* Set the report header */
			hdr.nr_zones = min_t(unsigned int,
					 (good_bytes - 64) / 64,
					 get_unaligned_be32(&buf[0]) / 64);
			memcpy(buf, &hdr, sizeof(struct blk_zone_report_hdr));
			offset += 64;
			bytes += 64;
		}

		/* Parse zone descriptors */
		while (offset < miter.length && hdr.nr_zones) {
			WARN_ON(offset > miter.length);
			buf = miter.addr + offset;
			sd_zbc_parse_report(sdkp, buf, &zone);
			memcpy(buf, &zone, sizeof(struct blk_zone));
			offset += 64;
			bytes += 64;
			hdr.nr_zones--;
		}

		if (!hdr.nr_zones)
			break;

	}

static void aha1542_free_cmd(struct scsi_cmnd *cmd)
{
	struct aha1542_cmd *acmd = scsi_cmd_priv(cmd);
	struct device *dev = cmd->device->host->dma_dev;
	size_t len = scsi_sg_count(cmd) * sizeof(struct chain);

	if (acmd->chain) {
		dma_unmap_single(dev, acmd->chain_handle, len, DMA_TO_DEVICE);
		kfree(acmd->chain);
	}

	acmd->chain = NULL;
	scsi_dma_unmap(cmd);
}

static void mts_do_sg (struct urb* transfer)
{
	struct scatterlist * sg;
	int status = transfer->status;
	MTS_INT_INIT();

	MTS_DEBUG("Processing fragment %d of %d\n", context->fragment,
	                                          scsi_sg_count(context->srb));

	if (unlikely(status)) {
                context->srb->result = (status == -ENOENT ? DID_ABORT : DID_ERROR)<<16;
		mts_transfer_cleanup(transfer);
        }

	sg = scsi_sglist(context->srb);
	context->fragment++;
	mts_int_submit_urb(transfer,
			   context->data_pipe,
			   sg_virt(&sg[context->fragment]),
			   sg[context->fragment].length,
			   context->fragment + 1 == scsi_sg_count(context->srb) ?
			   mts_data_done : mts_do_sg);
}

/*
 * Common used function. Transfer a complete command
 * via usb_stor_bulk_transfer_sglist() above. Set cmnd resid
 */
int usb_stor_bulk_srb(struct us_data* us, unsigned int pipe,
		      struct scsi_cmnd* srb)
{
	unsigned int partial;
	
//ALPS00445134, add more debug message for CR debugging
	US_DEBUGP("%s, line %d: \n", __func__, __LINE__);
//ALPS00445134, add more debug message for CR debugging

	int result = usb_stor_bulk_transfer_sglist(us, pipe, scsi_sglist(srb),
				      scsi_sg_count(srb), scsi_bufflen(srb),
				      &partial);

	scsi_set_resid(srb, scsi_bufflen(srb) - partial);
	return result;
}

/*
 * Called by struct target_core_fabric_ops->new_cmd_map()
 *
 * Always called in process context.  A non zero return value
 * here will signal to handle an exception based on the return code.
 */
static int tcm_loop_new_cmd_map(struct se_cmd *se_cmd)
{
    struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
                                  struct tcm_loop_cmd, tl_se_cmd);
    struct scsi_cmnd *sc = tl_cmd->sc;
    struct scatterlist *sgl_bidi = NULL;
    u32 sgl_bidi_count = 0;
    int ret;
    /*
     * Allocate the necessary tasks to complete the received CDB+data
     */
    ret = transport_generic_allocate_tasks(se_cmd, sc->cmnd);
    if (ret != 0)
        return ret;
    /*
     * For BIDI commands, pass in the extra READ buffer
     * to transport_generic_map_mem_to_cmd() below..
     */
    if (se_cmd->se_cmd_flags & SCF_BIDI) {
        struct scsi_data_buffer *sdb = scsi_in(sc);

        sgl_bidi = sdb->table.sgl;
        sgl_bidi_count = sdb->table.nents;
    }
    /*
     * Because some userspace code via scsi-generic do not memset their
     * associated read buffers, go ahead and do that here for type
     * SCF_SCSI_CONTROL_SG_IO_CDB.  Also note that this is currently
     * guaranteed to be a single SGL for SCF_SCSI_CONTROL_SG_IO_CDB
     * by target core in transport_generic_allocate_tasks() ->
     * transport_generic_cmd_sequencer().
     */
    if (se_cmd->se_cmd_flags & SCF_SCSI_CONTROL_SG_IO_CDB &&
            se_cmd->data_direction == DMA_FROM_DEVICE) {
        struct scatterlist *sg = scsi_sglist(sc);
        unsigned char *buf = kmap(sg_page(sg)) + sg->offset;

        if (buf != NULL) {
            memset(buf, 0, sg->length);
            kunmap(sg_page(sg));
        }
    }

    /* Tell the core about our preallocated memory */
    return transport_generic_map_mem_to_cmd(se_cmd, scsi_sglist(sc),
                                            scsi_sg_count(sc), sgl_bidi, sgl_bidi_count);
}