rpcrdma: Fix SQ size calculation when memreg is FRMR

This patch updates the computation to include the worst case situation
where three FRMR are required to map a single RPC REQ.

Signed-off-by: Tom Tucker <tom@ogc.us>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

2 files changed, 18 insertions, 4 deletions

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index e5e28d1946a4..2ac3f6e8adff 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -249,6 +249,8 @@ rpcrdma_create_chunks(struct rpc_rqst *rqst, struct xdr_buf *target,
         req->rl_nchunks = nchunks;
 
         BUG_ON(nchunks == 0);
+        BUG_ON((r_xprt->rx_ia.ri_memreg_strategy == RPCRDMA_FRMR)
+               && (nchunks > 3));
 
         /*
          * finish off header. If write, marshal discrim and nchunks.
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 3bdbd9f3b88f..5f4c7b3bc711 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -650,10 +650,22 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
         ep->rep_attr.cap.max_send_wr = cdata->max_requests;
         switch (ia->ri_memreg_strategy) {
         case RPCRDMA_FRMR:
-                /* Add room for frmr register and invalidate WRs */
-                ep->rep_attr.cap.max_send_wr *= 3;
-                if (ep->rep_attr.cap.max_send_wr > devattr.max_qp_wr)
-                        return -EINVAL;
+                /* Add room for frmr register and invalidate WRs.
+                 * 1. FRMR reg WR for head
+                 * 2. FRMR invalidate WR for head
+                 * 3. FRMR reg WR for pagelist
+                 * 4. FRMR invalidate WR for pagelist
+                 * 5. FRMR reg WR for tail
+                 * 6. FRMR invalidate WR for tail
+                 * 7. The RDMA_SEND WR
+                 */
+                ep->rep_attr.cap.max_send_wr *= 7;
+                if (ep->rep_attr.cap.max_send_wr > devattr.max_qp_wr) {
+                        cdata->max_requests = devattr.max_qp_wr / 7;
+                        if (!cdata->max_requests)
+                                return -EINVAL;
+                        ep->rep_attr.cap.max_send_wr = cdata->max_requests * 7;
+                }
                 break;
         case RPCRDMA_MEMWINDOWS_ASYNC:
         case RPCRDMA_MEMWINDOWS: