Re: [PATCH RFC 2/2] RDMA/isert: Support iWARP transport

Sagi Grimberg
2015-06-25T16:51:10Z

On 6/25/2015 6:39 PM, Steve Wise wrote:
> Memory regions that are the target of an iWARP RDMA READ RESPONSE need
> REMOTE_WRITE access rights. So enable REMOTE_WRITE for iWARP devices.
>
> iWARP RDMA READ target sge depth is 1. So save the max_read_sge in
> the target device structure and use that when creating RDMA_READ work
> requests.

Hi Steve,

CC'ing target-devel...

>
> Signed-off-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
> Tested-by: Vasu Dev <vasu.dev-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> ---
> drivers/infiniband/ulp/isert/ib_isert.c | 55 ++++++++++++++++++++++++++-----
> drivers/infiniband/ulp/isert/ib_isert.h | 1 +
> 2 files changed, 48 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
> index 9e7b492..b5cde5d 100644
> --- a/drivers/infiniband/ulp/isert/ib_isert.c
> +++ b/drivers/infiniband/ulp/isert/ib_isert.c
> @@ -165,6 +165,11 @@ isert_create_qp(struct isert_conn *isert_conn,
> attr.cap.max_send_sge = max(2, device->dev_attr.max_sge - 2);
> isert_conn->max_sge = attr.cap.max_send_sge;
>
> + if (rdma_cap_read_multi_sge(device->ib_device, cma_id->port_num))
> + isert_conn->max_read_sge = isert_conn->max_sge;
> + else
> + isert_conn->max_read_sge = 1;
> +

I think it would make sense to change now max_sge to max_write_sge.

And, shouldn't we just use:
max_wr_sge = max(2, device->dev_attr.max_sge - 2);
max_rd_sge = device->dev_attr.max_sge_rd;

Does the Chelsio device reports max_sge_rd != 1 ?

> attr.cap.max_recv_sge = 1;
> attr.sq_sig_type = IB_SIGNAL_REQ_WR;
> attr.qp_type = IB_QPT_RC;
> @@ -348,6 +353,17 @@ out_cq:
> return ret;
> }
>
> +static int any_port_is_iwarp(struct isert_device *device)
> +{
> + int i;
> +
> + for (i = rdma_start_port(device->ib_device);
> + i <= rdma_end_port(device->ib_device); i++)
> + if (rdma_protocol_iwarp(device->ib_device, i))
> + return 1;
> + return 0;
> +}
> +

This does not look like it belongs here... Can we
place this in rdma_cm?

> static int
> isert_create_device_ib_res(struct isert_device *device)
> {
> @@ -383,7 +399,17 @@ isert_create_device_ib_res(struct isert_device *device)
> goto out_cq;
> }
>
> - device->mr = ib_get_dma_mr(device->pd, IB_ACCESS_LOCAL_WRITE);
> + /*
> + * IWARP transports need REMOTE_WRITE for MRs used as the target of
> + * an RDMA_READ. Since the DMA MR is used for all ports, then if
> + * any port is running IWARP, add REMOTE_WRITE.
> + */
> + if (any_port_is_iwarp(device))
> + device->mr = ib_get_dma_mr(device->pd, IB_ACCESS_LOCAL_WRITE |
> + IB_ACCESS_REMOTE_WRITE);
> + else
> + device->mr = ib_get_dma_mr(device->pd, IB_ACCESS_LOCAL_WRITE);
> +
> if (IS_ERR(device->mr)) {
> ret = PTR_ERR(device->mr);
> isert_err("failed to create dma mr, device %p, ret=%d\n",
> @@ -2375,7 +2401,7 @@ isert_put_text_rsp(struct iscsi_cmd *cmd, struct iscsi_conn *conn)
> static int
> isert_build_rdma_wr(struct isert_conn *isert_conn, struct isert_cmd *isert_cmd,
> struct ib_sge *ib_sge, struct ib_send_wr *send_wr,
> - u32 data_left, u32 offset)
> + u32 data_left, u32 offset, u32 max_sge)
> {
> struct iscsi_cmd *cmd = isert_cmd->iscsi_cmd;
> struct scatterlist *sg_start, *tmp_sg;
> @@ -2386,7 +2412,7 @@ isert_build_rdma_wr(struct isert_conn *isert_conn, struct isert_cmd *isert_cmd,
>
> sg_off = offset / PAGE_SIZE;
> sg_start = &cmd->se_cmd.t_data_sg[sg_off];
> - sg_nents = min(cmd->se_cmd.t_data_nents - sg_off, isert_conn->max_sge);
> + sg_nents = min(cmd->se_cmd.t_data_nents - sg_off, max_sge);
> page_off = offset % PAGE_SIZE;
>
> send_wr->sg_list = ib_sge;
> @@ -2430,8 +2456,9 @@ isert_map_rdma(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
> struct isert_data_buf *data = &wr->data;
> struct ib_send_wr *send_wr;
> struct ib_sge *ib_sge;
> - u32 offset, data_len, data_left, rdma_write_max, va_offset = 0;
> + u32 offset, data_len, data_left, rdma_max_len, va_offset = 0;
> int ret = 0, i, ib_sge_cnt;
> + u32 max_sge;
>
> isert_cmd->tx_desc.isert_cmd = isert_cmd;
>
> @@ -2453,7 +2480,12 @@ isert_map_rdma(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
> }
> wr->ib_sge = ib_sge;
>
> - wr->send_wr_num = DIV_ROUND_UP(data->nents, isert_conn->max_sge);
> + if (wr->iser_ib_op == ISER_IB_RDMA_WRITE)
> + max_sge = isert_conn->max_sge;
> + else
> + max_sge = isert_conn->max_read_sge;
> +
> + wr->send_wr_num = DIV_ROUND_UP(data->nents, max_sge);
> wr->send_wr = kzalloc(sizeof(struct ib_send_wr) * wr->send_wr_num,
> GFP_KERNEL);
> if (!wr->send_wr) {
> @@ -2463,11 +2495,11 @@ isert_map_rdma(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
> }
>
> wr->isert_cmd = isert_cmd;
> - rdma_write_max = isert_conn->max_sge * PAGE_SIZE;
>
> + rdma_max_len = max_sge * PAGE_SIZE;
> for (i = 0; i < wr->send_wr_num; i++) {
> send_wr = &isert_cmd->rdma_wr.send_wr[i];
> - data_len = min(data_left, rdma_write_max);
> + data_len = min(data_left, rdma_max_len);
>
> send_wr->send_flags = 0;
> if (wr->iser_ib_op == ISER_IB_RDMA_WRITE) {
> @@ -2489,7 +2521,7 @@ isert_map_rdma(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
> }
>
> ib_sge_cnt = isert_build_rdma_wr(isert_conn, isert_cmd, ib_sge,
> - send_wr, data_len, offset);
> + send_wr, data_len, offset, max_sge);
> ib_sge += ib_sge_cnt;
>
> offset += data_len;
> @@ -2618,6 +2650,13 @@ isert_fast_reg_mr(struct isert_conn *isert_conn,
> fr_wr.wr.fast_reg.rkey = mr->rkey;
> fr_wr.wr.fast_reg.access_flags = IB_ACCESS_LOCAL_WRITE;
>
> + /*
> + * IWARP transports need REMOTE_WRITE for MRs used as the target of
> + * an RDMA_READ.
> + */
> + if (rdma_protocol_iwarp(ib_dev, isert_conn->cm_id->port_num))
> + fr_wr.wr.fast_reg.access_flags |= IB_ACCESS_REMOTE_WRITE;
> +
> if (!wr)
> wr = &fr_wr;
> else
> diff --git a/drivers/infiniband/ulp/isert/ib_isert.h b/drivers/infiniband/ulp/isert/ib_isert.h
> index 9ec23a7..47cf11b 100644
> --- a/drivers/infiniband/ulp/isert/ib_isert.h
> +++ b/drivers/infiniband/ulp/isert/ib_isert.h
> @@ -153,6 +153,7 @@ struct isert_conn {
> u32 initiator_depth;
> bool pi_support;
> u32 max_sge;
> + u32 max_read_sge;
> char *login_buf;
> char *login_req_buf;
> char *login_rsp_buf;