static struct sk_buff *ipoib_cm_alloc_rx_skb(struct net_device *dev,
					     struct ipoib_cm_rx_buf *rx_ring,
					     int id, int frags,
					     u64 mapping[IPOIB_CM_RX_SG])
{
	struct ipoib_dev_priv *priv = netdev_priv(dev);
	struct sk_buff *skb;
	int i;

	skb = dev_alloc_skb(IPOIB_CM_HEAD_SIZE + 12);
	if (unlikely(!skb))
		return NULL;

	/*
	 * IPoIB adds a 4 byte header. So we need 12 more bytes to align the
	 * IP header to a multiple of 16.
	 */
	skb_reserve(skb, 12);

	mapping[0] = ib_dma_map_single(priv->ca, skb->data, IPOIB_CM_HEAD_SIZE,
				       DMA_FROM_DEVICE);
	if (unlikely(ib_dma_mapping_error(priv->ca, mapping[0]))) {
		dev_kfree_skb_any(skb);
		return NULL;
	}

	for (i = 0; i < frags; i++) {
		struct page *page = alloc_page(GFP_ATOMIC);

		if (!page)
			goto partial_error;
		skb_fill_page_desc(skb, i, page, 0, PAGE_SIZE);

		mapping[i + 1] = ib_dma_map_page(priv->ca, skb_shinfo(skb)->frags[i].page,
						 0, PAGE_SIZE, DMA_FROM_DEVICE);
		if (unlikely(ib_dma_mapping_error(priv->ca, mapping[i + 1])))
			goto partial_error;
	}

	rx_ring[id].skb = skb;
	return skb;

partial_error:

	ib_dma_unmap_single(priv->ca, mapping[0], IPOIB_CM_HEAD_SIZE, DMA_FROM_DEVICE);

	for (; i > 0; --i)
		ib_dma_unmap_single(priv->ca, mapping[i], PAGE_SIZE, DMA_FROM_DEVICE);

	dev_kfree_skb_any(skb);
	return NULL;
}

int iser_alloc_rx_descriptors(struct iser_conn *iser_conn,
			      struct iscsi_session *session)
{
	int i, j;
	u64 dma_addr;
	struct iser_rx_desc *rx_desc;
	struct ib_sge       *rx_sg;
	struct ib_conn *ib_conn = &iser_conn->ib_conn;
	struct iser_device *device = ib_conn->device;

	iser_conn->qp_max_recv_dtos = session->cmds_max;
	iser_conn->qp_max_recv_dtos_mask = session->cmds_max - 1; /* cmds_max is 2^N */
	iser_conn->min_posted_rx = iser_conn->qp_max_recv_dtos >> 2;

	if (device->iser_alloc_rdma_reg_res(ib_conn, session->scsi_cmds_max))
		goto create_rdma_reg_res_failed;

	if (iser_alloc_login_buf(iser_conn))
		goto alloc_login_buf_fail;

	iser_conn->num_rx_descs = session->cmds_max;
	iser_conn->rx_descs = kmalloc(iser_conn->num_rx_descs *
				sizeof(struct iser_rx_desc), GFP_KERNEL);
	if (!iser_conn->rx_descs)
		goto rx_desc_alloc_fail;

	rx_desc = iser_conn->rx_descs;

	for (i = 0; i < iser_conn->qp_max_recv_dtos; i++, rx_desc++)  {
		dma_addr = ib_dma_map_single(device->ib_device, (void *)rx_desc,
					ISER_RX_PAYLOAD_SIZE, DMA_FROM_DEVICE);
		if (ib_dma_mapping_error(device->ib_device, dma_addr))
			goto rx_desc_dma_map_failed;

		rx_desc->dma_addr = dma_addr;

		rx_sg = &rx_desc->rx_sg;
		rx_sg->addr   = rx_desc->dma_addr;
		rx_sg->length = ISER_RX_PAYLOAD_SIZE;
		rx_sg->lkey   = device->mr->lkey;
	}

	iser_conn->rx_desc_head = 0;
	return 0;

rx_desc_dma_map_failed:
	rx_desc = iser_conn->rx_descs;
	for (j = 0; j < i; j++, rx_desc++)
		ib_dma_unmap_single(device->ib_device, rx_desc->dma_addr,
				    ISER_RX_PAYLOAD_SIZE, DMA_FROM_DEVICE);
	kfree(iser_conn->rx_descs);
	iser_conn->rx_descs = NULL;
rx_desc_alloc_fail:
	iser_free_login_buf(iser_conn);
alloc_login_buf_fail:
	device->iser_free_rdma_reg_res(ib_conn);
create_rdma_reg_res_failed:
	iser_err("failed allocating rx descriptors / data buffers\n");
	return -ENOMEM;
}

static int rdma_set_ctxt_sge(struct svcxprt_rdma *xprt,
			     struct svc_rdma_op_ctxt *ctxt,
			     struct svc_rdma_fastreg_mr *frmr,
			     struct kvec *vec,
			     u64 *sgl_offset,
			     int count)
{
	int i;

	ctxt->count = count;
	ctxt->direction = DMA_FROM_DEVICE;
	for (i = 0; i < count; i++) {
		ctxt->sge[i].length = 0; /* in case map fails */
		if (!frmr) {
			ctxt->sge[i].addr =
				ib_dma_map_single(xprt->sc_cm_id->device,
						  vec[i].iov_base,
						  vec[i].iov_len,
						  DMA_FROM_DEVICE);
			if (ib_dma_mapping_error(xprt->sc_cm_id->device,
						 ctxt->sge[i].addr))
				return -EINVAL;
			ctxt->sge[i].lkey = xprt->sc_dma_lkey;
			atomic_inc(&xprt->sc_dma_used);
		} else {
			ctxt->sge[i].addr = (unsigned long)vec[i].iov_base;
			ctxt->sge[i].lkey = frmr->mr->lkey;
		}
		ctxt->sge[i].length = vec[i].iov_len;
		*sgl_offset = *sgl_offset + vec[i].iov_len;
	}
	return 0;
}

struct sk_buff *vnic_alloc_rx_skb(struct vnic_rx_ring *ring, int buf_ind,
				  gfp_t gfp_flag)
{
	struct ib_device *ca = ring->port->dev->ca;
	struct sk_buff *skb;
	u64 mapping;
	int buf_size = VNIC_BUF_SIZE(ring->port);

	skb = alloc_skb(buf_size, gfp_flag);
	if (!skb) {
		vnic_dbg_data(ring->port->name,
			      "alloc_skb for size %d failed\n", buf_size);
		goto err_alloc;
	}

	mapping = ib_dma_map_single(ca, skb->data, buf_size, DMA_FROM_DEVICE);
	if (unlikely(ib_dma_mapping_error(ca, mapping))) {
		vnic_dbg_data(ring->port->name,
			      "ib_dma_map_single len %d failed\n", buf_size);
		goto err_map;
	}

	ring->rx_info[buf_ind].skb = skb;
	ring->rx_info[buf_ind].dma_addr[0] = mapping;

	return skb;

err_map:
	dev_kfree_skb_any(skb);
err_alloc:
	return NULL;
}

static int
post_recv(struct p9_client *client, struct p9_rdma_context *c)
{
	struct p9_trans_rdma *rdma = client->trans;
	struct ib_recv_wr wr;
	struct ib_sge sge;

	c->busa = ib_dma_map_single(rdma->cm_id->device,
				    c->rc.sdata, client->msize,
				    DMA_FROM_DEVICE);
	if (ib_dma_mapping_error(rdma->cm_id->device, c->busa))
		goto error;

	c->cqe.done = recv_done;

	sge.addr = c->busa;
	sge.length = client->msize;
	sge.lkey = rdma->pd->local_dma_lkey;

	wr.next = NULL;
	wr.wr_cqe = &c->cqe;
	wr.sg_list = &sge;
	wr.num_sge = 1;
	return ib_post_recv(rdma->qp, &wr, NULL);

 error:
	p9_debug(P9_DEBUG_ERROR, "EIO\n");
	return -EIO;
}

static int
post_recv(struct p9_client *client, struct p9_rdma_context *c)
{
	struct p9_trans_rdma *rdma = client->trans;
	struct ib_recv_wr wr, *bad_wr;
	struct ib_sge sge;

	c->busa = ib_dma_map_single(rdma->cm_id->device,
				    c->rc->sdata, client->msize,
				    DMA_FROM_DEVICE);
	if (ib_dma_mapping_error(rdma->cm_id->device, c->busa))
		goto error;

	sge.addr = c->busa;
	sge.length = client->msize;
	sge.lkey = rdma->lkey;

	wr.next = NULL;
	c->wc_op = IB_WC_RECV;
	wr.wr_id = (unsigned long) c;
	wr.sg_list = &sge;
	wr.num_sge = 1;
	return ib_post_recv(rdma->qp, &wr, &bad_wr);

 error:
	p9_debug(P9_DEBUG_ERROR, "EIO\n");
	return -EIO;
}

static int iser_alloc_login_buf(struct iser_conn *iser_conn)
{
	struct iser_device *device = iser_conn->ib_conn.device;
	int			req_err, resp_err;

	BUG_ON(device == NULL);

	iser_conn->login_buf = kmalloc(ISCSI_DEF_MAX_RECV_SEG_LEN +
				     ISER_RX_LOGIN_SIZE, GFP_KERNEL);
	if (!iser_conn->login_buf)
		goto out_err;

	iser_conn->login_req_buf  = iser_conn->login_buf;
	iser_conn->login_resp_buf = iser_conn->login_buf +
						ISCSI_DEF_MAX_RECV_SEG_LEN;

	iser_conn->login_req_dma = ib_dma_map_single(device->ib_device,
						     iser_conn->login_req_buf,
						     ISCSI_DEF_MAX_RECV_SEG_LEN,
						     DMA_TO_DEVICE);

	iser_conn->login_resp_dma = ib_dma_map_single(device->ib_device,
						      iser_conn->login_resp_buf,
						      ISER_RX_LOGIN_SIZE,
						      DMA_FROM_DEVICE);

	req_err  = ib_dma_mapping_error(device->ib_device,
					iser_conn->login_req_dma);
	resp_err = ib_dma_mapping_error(device->ib_device,
					iser_conn->login_resp_dma);

	if (req_err || resp_err) {
		if (req_err)
			iser_conn->login_req_dma = 0;
		if (resp_err)
			iser_conn->login_resp_dma = 0;
		goto free_login_buf;
	}
	return 0;

free_login_buf:
	iser_free_login_buf(iser_conn);

out_err:
	iser_err("unable to alloc or map login buf\n");
	return -ENOMEM;
}

/* Send a backwards direction RPC call.
 *
 * Caller holds the connection's mutex and has already marshaled
 * the RPC/RDMA request.
 *
 * This is similar to svc_rdma_reply, but takes an rpc_rqst
 * instead, does not support chunks, and avoids blocking memory
 * allocation.
 *
 * XXX: There is still an opportunity to block in svc_rdma_send()
 * if there are no SQ entries to post the Send. This may occur if
 * the adapter has a small maximum SQ depth.
 */
static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
			      struct rpc_rqst *rqst)
{
	struct xdr_buf *sndbuf = &rqst->rq_snd_buf;
	struct svc_rdma_op_ctxt *ctxt;
	struct svc_rdma_req_map *vec;
	struct ib_send_wr send_wr;
	int ret;

	vec = svc_rdma_get_req_map(rdma);
	ret = svc_rdma_map_xdr(rdma, sndbuf, vec, false);
	if (ret)
		goto out_err;

	ret = svc_rdma_repost_recv(rdma, GFP_NOIO);
	if (ret)
		goto out_err;

	ctxt = svc_rdma_get_context(rdma);
	ctxt->pages[0] = virt_to_page(rqst->rq_buffer);
	ctxt->count = 1;

	ctxt->direction = DMA_TO_DEVICE;
	ctxt->sge[0].lkey = rdma->sc_pd->local_dma_lkey;
	ctxt->sge[0].length = sndbuf->len;
	ctxt->sge[0].addr =
	    ib_dma_map_page(rdma->sc_cm_id->device, ctxt->pages[0], 0,
			    sndbuf->len, DMA_TO_DEVICE);
	if (ib_dma_mapping_error(rdma->sc_cm_id->device, ctxt->sge[0].addr)) {
		ret = -EIO;
		goto out_unmap;
	}
	svc_rdma_count_mappings(rdma, ctxt);

	memset(&send_wr, 0, sizeof(send_wr));
	ctxt->cqe.done = svc_rdma_wc_send;
	send_wr.wr_cqe = &ctxt->cqe;
	send_wr.sg_list = ctxt->sge;
	send_wr.num_sge = 1;
	send_wr.opcode = IB_WR_SEND;
	send_wr.send_flags = IB_SEND_SIGNALED;

	ret = svc_rdma_send(rdma, &send_wr);
	if (ret) {
		ret = -EIO;
		goto out_unmap;
	}

out_err:
	svc_rdma_put_req_map(rdma, vec);
	dprintk("svcrdma: %s returns %d\n", __func__, ret);
	return ret;

out_unmap:
	svc_rdma_unmap_dma(ctxt);
	svc_rdma_put_context(ctxt, 1);
	goto out_err;
}

/*
 * allocate a single fragment on a single ring entry and map it
 * to HW address.
 */
static int vnic_alloc_frag(struct vnic_rx_ring *ring,
			   struct vnic_frag_data *frags_data, int i)
{
	struct vnic_frag_info *frag_info = &ring->frag_info[i];
	struct vnic_rx_alloc *page_alloc = &ring->page_alloc[i];
	struct skb_frag_struct *skb_frags = &frags_data->frags[i];
	struct skb_frag_struct skbf = *skb_frags;
	struct page *page;	
	struct ib_device *ib_device = ring->port->dev->ca;
	u64 dma;
	int decision;

	if (vnic_rx_linear)
		return 0;

	if (page_alloc->offset >= frag_info->last_offset) {
		decision = 0;
		/* Allocate new page */
		page = alloc_pages(GFP_ATOMIC | __GFP_COMP, VNIC_ALLOC_ORDER);
		if (!page) {
			/*frags_data->dma_addr[i] = NULL;
			   ring->rx_info[wr_id].info = VNIC_FRAG_ALLOC_FAIL;
			   ring->need_refill = 1; */
			return -ENOMEM;
		}
		skbf.page.p = page_alloc->page;
		skbf.page_offset = page_alloc->offset;
	} else {
		decision = 1;
		page = page_alloc->page;
		get_page(page);
		skbf.page.p = page;
		skbf.page_offset = page_alloc->offset;
	}

	skbf.size = frag_info->frag_size;
	dma = ib_dma_map_single(ib_device, page_address(skbf.page.p) +
			     skbf.page_offset, frag_info->frag_size,
			     PCI_DMA_FROMDEVICE);
	if (unlikely(ib_dma_mapping_error(ib_device, dma))) {
		vnic_dbg_data(ring->port->name,
			      "ib_dma_map_single len %d failed\n",
			      frag_info->frag_size);
		put_page(page);
		return -ENOMEM;
	}

	if (!decision) {
		page_alloc->page = page;
		page_alloc->offset = frag_info->frag_align;
	} else
		page_alloc->offset += frag_info->frag_stride;

	*skb_frags = skbf;
	frags_data->dma_addr[i] = dma;

	return 0;
}

/*
 * Map for DMA and insert a single page into the on-demand paging page tables.
 *
 * @umem: the umem to insert the page to.
 * @page_index: index in the umem to add the page to.
 * @page: the page struct to map and add.
 * @access_mask: access permissions needed for this page.
 * @current_seq: sequence number for synchronization with invalidations.
 *               the sequence number is taken from
 *               umem->odp_data->notifiers_seq.
 *
 * The function returns -EFAULT if the DMA mapping operation fails. It returns
 * -EAGAIN if a concurrent invalidation prevents us from updating the page.
 *
 * The page is released via put_page even if the operation failed. For
 * on-demand pinning, the page is released whenever it isn't stored in the
 * umem.
 */
static int ib_umem_odp_map_dma_single_page(
		struct ib_umem *umem,
		int page_index,
		struct page *page,
		u64 access_mask,
		unsigned long current_seq,
		enum ib_odp_dma_map_flags flags)
{
	struct ib_device *dev = umem->context->device;
	dma_addr_t dma_addr;
	int stored_page = 0;
	int ret = 0;
	mutex_lock(&umem->odp_data->umem_mutex);
	/*
	 * Note: we avoid writing if seq is different from the initial seq, to
	 * handle case of a racing notifier. This check also allows us to bail
	 * early if we have a notifier running in parallel with us.
	 */
	if (ib_umem_mmu_notifier_retry(umem, current_seq)) {
		ret = -EAGAIN;
		goto out;
	}
	if (!(umem->odp_data->dma_list[page_index])) {
		dma_addr = ib_dma_map_page(dev,
					   page,
					   0, PAGE_SIZE,
					   DMA_BIDIRECTIONAL);
		if (ib_dma_mapping_error(dev, dma_addr)) {
			ret = -EFAULT;
			goto out;
		}
		umem->odp_data->dma_list[page_index] = dma_addr | access_mask;
		umem->odp_data->page_list[page_index] = page;
		if (flags & IB_ODP_DMA_MAP_FOR_PREFETCH)
			atomic_inc(&dev->odp_statistics.num_prefetch_pages);
		else
			atomic_inc(&dev->odp_statistics.num_page_fault_pages);

		stored_page = 1;
	} else if (umem->odp_data->page_list[page_index] == page) {
		umem->odp_data->dma_list[page_index] |= access_mask;
	} else {
		pr_err("error: got different pages in IB device and from get_user_pages. IB device page: %p, gup page: %p\n"
		       , umem->odp_data->page_list[page_index], page);
	}

out:
	mutex_unlock(&umem->odp_data->umem_mutex);

	/* On Demand Paging - avoid pinning the page */
	if (umem->context->invalidate_range || !stored_page)
		put_page(page);

	return ret;
}

static int
svc_rdma_post_recv(struct svcxprt_rdma *xprt)
{
	struct ib_recv_wr recv_wr, *bad_recv_wr;
	struct svc_rdma_op_ctxt *ctxt;
	struct page *page;
	dma_addr_t pa;
	int sge_no;
	int buflen;
	int ret;

	ctxt = svc_rdma_get_context(xprt);
	buflen = 0;
	ctxt->direction = DMA_FROM_DEVICE;
	ctxt->cqe.done = svc_rdma_wc_receive;
	for (sge_no = 0; buflen < xprt->sc_max_req_size; sge_no++) {
		if (sge_no >= xprt->sc_max_sge) {
			pr_err("svcrdma: Too many sges (%d)\n", sge_no);
			goto err_put_ctxt;
		}
		page = alloc_page(GFP_KERNEL);
		if (!page)
			goto err_put_ctxt;
		ctxt->pages[sge_no] = page;
		pa = ib_dma_map_page(xprt->sc_cm_id->device,
				     page, 0, PAGE_SIZE,
				     DMA_FROM_DEVICE);
		if (ib_dma_mapping_error(xprt->sc_cm_id->device, pa))
			goto err_put_ctxt;
		svc_rdma_count_mappings(xprt, ctxt);
		ctxt->sge[sge_no].addr = pa;
		ctxt->sge[sge_no].length = PAGE_SIZE;
		ctxt->sge[sge_no].lkey = xprt->sc_pd->local_dma_lkey;
		ctxt->count = sge_no + 1;
		buflen += PAGE_SIZE;
	}
	recv_wr.next = NULL;
	recv_wr.sg_list = &ctxt->sge[0];
	recv_wr.num_sge = ctxt->count;
	recv_wr.wr_cqe = &ctxt->cqe;

	svc_xprt_get(&xprt->sc_xprt);
	ret = ib_post_recv(xprt->sc_qp, &recv_wr, &bad_recv_wr);
	if (ret) {
		svc_rdma_unmap_dma(ctxt);
		svc_rdma_put_context(ctxt, 1);
		svc_xprt_put(&xprt->sc_xprt);
	}
	return ret;

 err_put_ctxt:
	svc_rdma_unmap_dma(ctxt);
	svc_rdma_put_context(ctxt, 1);
	return -ENOMEM;
}

static int iser_alloc_login_buf(struct iser_conn *iser_conn)
{
	struct iser_device *device = iser_conn->ib_conn.device;
	struct iser_login_desc *desc = &iser_conn->login_desc;

	desc->req = kmalloc(ISCSI_DEF_MAX_RECV_SEG_LEN, GFP_KERNEL);
	if (!desc->req)
		return -ENOMEM;

	desc->req_dma = ib_dma_map_single(device->ib_device, desc->req,
					  ISCSI_DEF_MAX_RECV_SEG_LEN,
					  DMA_TO_DEVICE);
	if (ib_dma_mapping_error(device->ib_device,
				desc->req_dma))
		goto free_req;

	desc->rsp = kmalloc(ISER_RX_LOGIN_SIZE, GFP_KERNEL);
	if (!desc->rsp)
		goto unmap_req;

	desc->rsp_dma = ib_dma_map_single(device->ib_device, desc->rsp,
					   ISER_RX_LOGIN_SIZE,
					   DMA_FROM_DEVICE);
	if (ib_dma_mapping_error(device->ib_device,
				desc->rsp_dma))
		goto free_rsp;

	return 0;

free_rsp:
	kfree(desc->rsp);
unmap_req:
	ib_dma_unmap_single(device->ib_device, desc->req_dma,
			    ISCSI_DEF_MAX_RECV_SEG_LEN,
			    DMA_TO_DEVICE);
free_req:
	kfree(desc->req);

	return -ENOMEM;
}

u64 rdma_map_address(void* addr, int length)
{
    u64 dma_addr;

    LOG_KERN(LOG_INFO, ("Mapping addr\n"));

    dma_addr = ib_dma_map_single(rdma_ib_device.dev, addr, length, DMA_BIDIRECTIONAL);
    if (ib_dma_mapping_error(rdma_ib_device.dev, dma_addr) != 0) {
        LOG_KERN(LOG_INFO, ("Error mapping myaddr"));
        return 0; //error
    }

    return dma_addr;
}

int svc_rdma_post_recv(struct svcxprt_rdma *xprt)
{
	struct ib_recv_wr recv_wr, *bad_recv_wr;
	struct svc_rdma_op_ctxt *ctxt;
	struct page *page;
	dma_addr_t pa;
	int sge_no;
	int buflen;
	int ret;

	ctxt = svc_rdma_get_context(xprt);
	buflen = 0;
	ctxt->direction = DMA_FROM_DEVICE;
	for (sge_no = 0; buflen < xprt->sc_max_req_size; sge_no++) {
		BUG_ON(sge_no >= xprt->sc_max_sge);
		page = svc_rdma_get_page();
		ctxt->pages[sge_no] = page;
		pa = ib_dma_map_page(xprt->sc_cm_id->device,
				     page, 0, PAGE_SIZE,
				     DMA_FROM_DEVICE);
		if (ib_dma_mapping_error(xprt->sc_cm_id->device, pa))
			goto err_put_ctxt;
		atomic_inc(&xprt->sc_dma_used);
		ctxt->sge[sge_no].addr = pa;
		ctxt->sge[sge_no].length = PAGE_SIZE;
		ctxt->sge[sge_no].lkey = xprt->sc_dma_lkey;
		ctxt->count = sge_no + 1;
		buflen += PAGE_SIZE;
	}
	recv_wr.next = NULL;
	recv_wr.sg_list = &ctxt->sge[0];
	recv_wr.num_sge = ctxt->count;
	recv_wr.wr_id = (u64)(unsigned long)ctxt;

	svc_xprt_get(&xprt->sc_xprt);
	ret = ib_post_recv(xprt->sc_qp, &recv_wr, &bad_recv_wr);
	if (ret) {
		svc_rdma_unmap_dma(ctxt);
		svc_rdma_put_context(ctxt, 1);
		svc_xprt_put(&xprt->sc_xprt);
	}
	return ret;

 err_put_ctxt:
	svc_rdma_unmap_dma(ctxt);
	svc_rdma_put_context(ctxt, 1);
	return -ENOMEM;
}

/**
 * iser_reg_single - fills registered buffer descriptor with
 *		     registration information
 */
void iser_reg_single(struct iser_device *device,
		     struct iser_regd_buf *regd_buf,
		     enum dma_data_direction direction)
{
	u64 dma_addr;

	dma_addr = ib_dma_map_single(device->ib_device,
				     regd_buf->virt_addr,
				     regd_buf->data_size, direction);
	BUG_ON(ib_dma_mapping_error(device->ib_device, dma_addr));

	regd_buf->reg.lkey = device->mr->lkey;
	regd_buf->reg.len  = regd_buf->data_size;
	regd_buf->reg.va   = dma_addr;
	regd_buf->reg.is_fmr = 0;

	regd_buf->dma_addr  = dma_addr;
	regd_buf->direction = direction;
}

int iser_alloc_rx_descriptors(struct iser_conn *ib_conn)
{
	int i, j;
	u64 dma_addr;
	struct iser_rx_desc *rx_desc;
	struct ib_sge       *rx_sg;
	struct iser_device  *device = ib_conn->device;

	ib_conn->rx_descs = kmalloc(ISER_QP_MAX_RECV_DTOS *
				sizeof(struct iser_rx_desc), GFP_KERNEL);
	if (!ib_conn->rx_descs)
		goto rx_desc_alloc_fail;

	rx_desc = ib_conn->rx_descs;

	for (i = 0; i < ISER_QP_MAX_RECV_DTOS; i++, rx_desc++)  {
		dma_addr = ib_dma_map_single(device->ib_device, (void *)rx_desc,
					ISER_RX_PAYLOAD_SIZE, DMA_FROM_DEVICE);
		if (ib_dma_mapping_error(device->ib_device, dma_addr))
			goto rx_desc_dma_map_failed;

		rx_desc->dma_addr = dma_addr;

		rx_sg = &rx_desc->rx_sg;
		rx_sg->addr   = rx_desc->dma_addr;
		rx_sg->length = ISER_RX_PAYLOAD_SIZE;
		rx_sg->lkey   = device->mr->lkey;
	}

	ib_conn->rx_desc_head = 0;
	return 0;

rx_desc_dma_map_failed:
	rx_desc = ib_conn->rx_descs;
	for (j = 0; j < i; j++, rx_desc++)
		ib_dma_unmap_single(device->ib_device, rx_desc->dma_addr,
			ISER_RX_PAYLOAD_SIZE, DMA_FROM_DEVICE);
	kfree(ib_conn->rx_descs);
	ib_conn->rx_descs = NULL;
rx_desc_alloc_fail:
	iser_err("failed allocating rx descriptors / data buffers\n");
	return -ENOMEM;
}

int iser_initialize_task_headers(struct iscsi_task *task,
						struct iser_tx_desc *tx_desc)
{
	struct iser_conn       *ib_conn   = task->conn->dd_data;
	struct iser_device     *device    = ib_conn->device;
	struct iscsi_iser_task *iser_task = task->dd_data;
	u64 dma_addr;

	dma_addr = ib_dma_map_single(device->ib_device, (void *)tx_desc,
				ISER_HEADERS_LEN, DMA_TO_DEVICE);
	if (ib_dma_mapping_error(device->ib_device, dma_addr))
		return -ENOMEM;

	tx_desc->dma_addr = dma_addr;
	tx_desc->tx_sg[0].addr   = tx_desc->dma_addr;
	tx_desc->tx_sg[0].length = ISER_HEADERS_LEN;
	tx_desc->tx_sg[0].lkey   = device->mr->lkey;

	iser_task->ib_conn = ib_conn;
	return 0;
}

/**
 * iser_initialize_task_headers() - Initialize task headers
 * @task:       iscsi task
 * @tx_desc:    iser tx descriptor
 *
 * Notes:
 * This routine may race with iser teardown flow for scsi
 * error handling TMFs. So for TMF we should acquire the
 * state mutex to avoid dereferencing the IB device which
 * may have already been terminated.
 */
int
iser_initialize_task_headers(struct iscsi_task *task,
			     struct iser_tx_desc *tx_desc)
{
	struct iser_conn *iser_conn = task->conn->dd_data;
	struct iser_device *device = iser_conn->ib_conn.device;
	struct iscsi_iser_task *iser_task = task->dd_data;
	u64 dma_addr;
	const bool mgmt_task = !task->sc && !in_interrupt();
	int ret = 0;

	if (unlikely(mgmt_task))
		mutex_lock(&iser_conn->state_mutex);

	if (unlikely(iser_conn->state != ISER_CONN_UP)) {
		ret = -ENODEV;
		goto out;
	}

	dma_addr = ib_dma_map_single(device->ib_device, (void *)tx_desc,
				ISER_HEADERS_LEN, DMA_TO_DEVICE);
	if (ib_dma_mapping_error(device->ib_device, dma_addr)) {
		ret = -ENOMEM;
		goto out;
	}

	tx_desc->wr_idx = 0;
	tx_desc->mapped = true;
	tx_desc->dma_addr = dma_addr;
	tx_desc->tx_sg[0].addr   = tx_desc->dma_addr;
	tx_desc->tx_sg[0].length = ISER_HEADERS_LEN;
	tx_desc->tx_sg[0].lkey   = device->pd->local_dma_lkey;

	iser_task->iser_conn = iser_conn;
out:
	if (unlikely(mgmt_task))
		mutex_unlock(&iser_conn->state_mutex);

	return ret;
}

static struct svc_rdma_recv_ctxt *
svc_rdma_recv_ctxt_alloc(struct svcxprt_rdma *rdma)
{
	struct svc_rdma_recv_ctxt *ctxt;
	dma_addr_t addr;
	void *buffer;

	ctxt = kmalloc(sizeof(*ctxt), GFP_KERNEL);
	if (!ctxt)
		goto fail0;
	buffer = kmalloc(rdma->sc_max_req_size, GFP_KERNEL);
	if (!buffer)
		goto fail1;
	addr = ib_dma_map_single(rdma->sc_pd->device, buffer,
				 rdma->sc_max_req_size, DMA_FROM_DEVICE);
	if (ib_dma_mapping_error(rdma->sc_pd->device, addr))
		goto fail2;

	ctxt->rc_recv_wr.next = NULL;
	ctxt->rc_recv_wr.wr_cqe = &ctxt->rc_cqe;
	ctxt->rc_recv_wr.sg_list = &ctxt->rc_recv_sge;
	ctxt->rc_recv_wr.num_sge = 1;
	ctxt->rc_cqe.done = svc_rdma_wc_receive;
	ctxt->rc_recv_sge.addr = addr;
	ctxt->rc_recv_sge.length = rdma->sc_max_req_size;
	ctxt->rc_recv_sge.lkey = rdma->sc_pd->local_dma_lkey;
	ctxt->rc_recv_buf = buffer;
	ctxt->rc_temp = false;
	return ctxt;

fail2:
	kfree(buffer);
fail1:
	kfree(ctxt);
fail0:
	return NULL;
}

static int rdma_setup(rdma_ctx_t ctx)
{
    // create receive buffer
    ctx->rdma_recv_buffer = kmalloc(RDMA_BUFFER_SIZE, GFP_KERNEL);
    CHECK_MSG_RET(ctx->rdma_recv_buffer != 0, "Error kmalloc", -1);

    // create memory region
    ctx->mr = ib_get_dma_mr(ctx->pd, IB_ACCESS_REMOTE_READ | 
                                     IB_ACCESS_REMOTE_WRITE | 
                                     IB_ACCESS_LOCAL_WRITE);
    CHECK_MSG_RET(ctx->mr != 0, "Error creating MR", -1);

    ctx->rkey = ctx->mr->rkey;

    // get dma_addr
    ctx->dma_addr = ib_dma_map_single(rdma_ib_device.dev, ctx->rdma_recv_buffer, 
            RDMA_BUFFER_SIZE, DMA_BIDIRECTIONAL);
    CHECK_MSG_RET(ib_dma_mapping_error(rdma_ib_device.dev, ctx->dma_addr) == 0,
            "Error ib_dma_map_single", -1);

    // modify QP until RTS
    modify_qp(ctx);
    return 0;
}