On Mon, Nov 19, 2018 at 10:46 AM Chuck Lever <chuck.lever@xxxxxxxxxx> wrote:
>
> Place the associated RPC transaction's XID in the upper 32 bits of
> each RDMA segment's rdma_offset field. These bits are currently
> always zero.
>
> There are two reasons to do this:
>
> - The R_key only has 8 bits that are different from registration to
> registration. The XID adds more uniqueness to each RDMA segment to
> reduce the likelihood of a software bug on the server reading from
> or writing into memory it's not supposed to.
>
> - On-the-wire RDMA Read and Write operations do not otherwise carry
> any identifier that matches them up to an RPC. The XID in the
> upper 32 bits will act as an eye-catcher in network captures.
Is this just an "eye-catcher" or do you have plans to use it in
wireshark? If the latter, then can we really do that? while a linux
implementation may do that, other (or even possibly future linux)
implementation might not do this. Can we justify changing the
wireshark logic for it?
> Suggested-by: Tom Talpey <ttalpey@xxxxxxxxxxxxx>
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> ---
> net/sunrpc/xprtrdma/frwr_ops.c | 3 ++-
> net/sunrpc/xprtrdma/rpc_rdma.c | 6 +++---
> net/sunrpc/xprtrdma/xprt_rdma.h | 2 +-
> 3 files changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
> index 49b314d..3b260d2 100644
> --- a/net/sunrpc/xprtrdma/frwr_ops.c
> +++ b/net/sunrpc/xprtrdma/frwr_ops.c
> @@ -344,7 +344,7 @@
> */
> static struct rpcrdma_mr_seg *
> frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
> - int nsegs, bool writing, struct rpcrdma_mr **out)
> + int nsegs, bool writing, u32 xid, struct rpcrdma_mr **out)
> {
> struct rpcrdma_ia *ia = &r_xprt->rx_ia;
> bool holes_ok = ia->ri_mrtype == IB_MR_TYPE_SG_GAPS;
> @@ -398,6 +398,7 @@
> if (unlikely(n != mr->mr_nents))
> goto out_mapmr_err;
>
> + ibmr->iova |= ((u64)cpu_to_be32(xid)) << 32;
> key = (u8)(ibmr->rkey & 0x000000FF);
> ib_update_fast_reg_key(ibmr, ++key);
>
> diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
> index 9f53e02..89a2db2 100644
> --- a/net/sunrpc/xprtrdma/rpc_rdma.c
> +++ b/net/sunrpc/xprtrdma/rpc_rdma.c
> @@ -357,7 +357,7 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
>
> do {
> seg = r_xprt->rx_ia.ri_ops->ro_map(r_xprt, seg, nsegs,
> - false, &mr);
> + false, rqst->rq_xid, &mr);
> if (IS_ERR(seg))
> return PTR_ERR(seg);
> rpcrdma_mr_push(mr, &req->rl_registered);
> @@ -415,7 +415,7 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
> nchunks = 0;
> do {
> seg = r_xprt->rx_ia.ri_ops->ro_map(r_xprt, seg, nsegs,
> - true, &mr);
> + true, rqst->rq_xid, &mr);
> if (IS_ERR(seg))
> return PTR_ERR(seg);
> rpcrdma_mr_push(mr, &req->rl_registered);
> @@ -473,7 +473,7 @@ static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
> nchunks = 0;
> do {
> seg = r_xprt->rx_ia.ri_ops->ro_map(r_xprt, seg, nsegs,
> - true, &mr);
> + true, rqst->rq_xid, &mr);
> if (IS_ERR(seg))
> return PTR_ERR(seg);
> rpcrdma_mr_push(mr, &req->rl_registered);
> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
> index a13ccb6..2ae1ee2 100644
> --- a/net/sunrpc/xprtrdma/xprt_rdma.h
> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h
> @@ -472,7 +472,7 @@ struct rpcrdma_memreg_ops {
> struct rpcrdma_mr_seg *
> (*ro_map)(struct rpcrdma_xprt *,
> struct rpcrdma_mr_seg *, int, bool,
> - struct rpcrdma_mr **);
> + u32, struct rpcrdma_mr **);
> int (*ro_send)(struct rpcrdma_ia *ia,
> struct rpcrdma_req *req);
> void (*ro_reminv)(struct rpcrdma_rep *rep,
>
