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

Steve Wise
2015-06-25T15:39:23Z

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.

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;
+
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;
+}
+
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;