svcrdma: Plant reader function in struct svcxprt_rdma

The RDMA reader function doesn't change once an svcxprt_rdma is
instantiated. Instead of checking sc_devcap during every incoming
RPC, set the reader function once when the connection is accepted.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

2 files changed, 29 insertions, 44 deletions

diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index 577f8659ca30..c3aebc1bf0a6 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -117,26 +117,16 @@ static int rdma_read_max_sge(struct svcxprt_rdma *xprt, int sge_count)
                 return min_t(int, sge_count, xprt->sc_max_sge);
 }
 
-typedef int (*rdma_reader_fn)(struct svcxprt_rdma *xprt,
-                              struct svc_rqst *rqstp,
-                              struct svc_rdma_op_ctxt *head,
-                              int *page_no,
-                              u32 *page_offset,
-                              u32 rs_handle,
-                              u32 rs_length,
-                              u64 rs_offset,
-                              int last);
-
 /* Issue an RDMA_READ using the local lkey to map the data sink */
-static int rdma_read_chunk_lcl(struct svcxprt_rdma *xprt,
-                               struct svc_rqst *rqstp,
-                               struct svc_rdma_op_ctxt *head,
-                               int *page_no,
-                               u32 *page_offset,
-                               u32 rs_handle,
-                               u32 rs_length,
-                               u64 rs_offset,
-                               int last)
+int rdma_read_chunk_lcl(struct svcxprt_rdma *xprt,
+                        struct svc_rqst *rqstp,
+                        struct svc_rdma_op_ctxt *head,
+                        int *page_no,
+                        u32 *page_offset,
+                        u32 rs_handle,
+                        u32 rs_length,
+                        u64 rs_offset,
+                        bool last)
 {
         struct ib_send_wr read_wr;
         int pages_needed = PAGE_ALIGN(*page_offset + rs_length) >> PAGE_SHIFT;
@@ -221,15 +211,15 @@ static int rdma_read_chunk_lcl(struct svcxprt_rdma *xprt,
 }
 
 /* Issue an RDMA_READ using an FRMR to map the data sink */
-static int rdma_read_chunk_frmr(struct svcxprt_rdma *xprt,
-                                struct svc_rqst *rqstp,
-                                struct svc_rdma_op_ctxt *head,
-                                int *page_no,
-                                u32 *page_offset,
-                                u32 rs_handle,
-                                u32 rs_length,
-                                u64 rs_offset,
-                                int last)
+int rdma_read_chunk_frmr(struct svcxprt_rdma *xprt,
+                         struct svc_rqst *rqstp,
+                         struct svc_rdma_op_ctxt *head,
+                         int *page_no,
+                         u32 *page_offset,
+                         u32 rs_handle,
+                         u32 rs_length,
+                         u64 rs_offset,
+                         bool last)
 {
         struct ib_send_wr read_wr;
         struct ib_send_wr inv_wr;
@@ -374,9 +364,9 @@ static int rdma_read_chunks(struct svcxprt_rdma *xprt,
 {
         int page_no, ret;
         struct rpcrdma_read_chunk *ch;
-        u32 page_offset, byte_count;
+        u32 handle, page_offset, byte_count;
         u64 rs_offset;
-        rdma_reader_fn reader;
+        bool last;
 
         /* If no read list is present, return 0 */
         ch = svc_rdma_get_read_chunk(rmsgp);
@@ -399,27 +389,20 @@ static int rdma_read_chunks(struct svcxprt_rdma *xprt,
         head->arg.len = rqstp->rq_arg.len;
         head->arg.buflen = rqstp->rq_arg.buflen;
 
-        /* Use FRMR if supported */
-        if (xprt->sc_dev_caps & SVCRDMA_DEVCAP_FAST_REG)
-                reader = rdma_read_chunk_frmr;
-        else
-                reader = rdma_read_chunk_lcl;
-
         page_no = 0; page_offset = 0;
         for (ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];
              ch->rc_discrim != 0; ch++) {
-
+                handle = be32_to_cpu(ch->rc_target.rs_handle);
+                byte_count = be32_to_cpu(ch->rc_target.rs_length);
                 xdr_decode_hyper((__be32 *)&ch->rc_target.rs_offset,
                                  &rs_offset);
-                byte_count = ntohl(ch->rc_target.rs_length);
 
                 while (byte_count > 0) {
-                        ret = reader(xprt, rqstp, head,
-                                     &page_no, &page_offset,
-                                     ntohl(ch->rc_target.rs_handle),
-                                     byte_count, rs_offset,
-                                     ((ch+1)->rc_discrim == 0) /* last */
-                                     );
+                        last = (ch + 1)->rc_discrim == xdr_zero;
+                        ret = xprt->sc_reader(xprt, rqstp, head,
+                                              &page_no, &page_offset,
+                                              handle, byte_count,
+                                              rs_offset, last);
                         if (ret < 0)
                                 goto err;
                         byte_count -= ret;
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index f2e059bbab42..f609c1c2d38d 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -974,10 +974,12 @@ static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
          * NB:  iWARP requires remote write access for the data sink
          *      of an RDMA_READ. IB does not.
          */
+        newxprt->sc_reader = rdma_read_chunk_lcl;
         if (devattr.device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS) {
                 newxprt->sc_frmr_pg_list_len =
                         devattr.max_fast_reg_page_list_len;
                 newxprt->sc_dev_caps |= SVCRDMA_DEVCAP_FAST_REG;
+                newxprt->sc_reader = rdma_read_chunk_frmr;
         }
 
         /*