xprtrdma: Limit data payload size for ALLPHYSICAL

When the client uses physical memory registration, each page in the
payload gets its own array entry in the RPC/RDMA header's chunk list.

Therefore, don't advertise a maximum payload size that would require
more array entries than can fit in the RPC buffer where RPC/RDMA
headers are built.

BugLink: https://bugzilla.linux-nfs.org/show_bug.cgi?id=248
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Tested-by: Shirley Ma <shirley.ma@oracle.com>
Tested-by: Devesh Sharma <devesh.sharma@emulex.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

3 files changed, 45 insertions, 1 deletions

diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index 66f91f0d071a..418510202919 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -296,7 +296,6 @@ xprt_setup_rdma(struct xprt_create *args)
 
         xprt->resvport = 0;             /* privileged port not needed */
         xprt->tsh_size = 0;             /* RPC-RDMA handles framing */
-        xprt->max_payload = RPCRDMA_MAX_DATA_SEGS * PAGE_SIZE;
         xprt->ops = &xprt_rdma_procs;
 
         /*
@@ -382,6 +381,9 @@ xprt_setup_rdma(struct xprt_create *args)
         new_ep->rep_xprt = xprt;
 
         xprt_rdma_format_addresses(xprt);
+        xprt->max_payload = rpcrdma_max_payload(new_xprt);
+        dprintk("RPC:       %s: transport data payload maximum: %zu bytes\n",
+                __func__, xprt->max_payload);
 
         if (!try_module_get(THIS_MODULE))
                 goto out4;
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index aa08de89de42..13ff87400203 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -1825,3 +1825,44 @@ rpcrdma_ep_post_recv(struct rpcrdma_ia *ia,
                         rc);
         return rc;
 }
+
+/* Physical mapping means one Read/Write list entry per-page.
+ * All list entries must fit within an inline buffer
+ *
+ * NB: The server must return a Write list for NFS READ,
+ *     which has the same constraint. Factor in the inline
+ *     rsize as well.
+ */
+static size_t
+rpcrdma_physical_max_payload(struct rpcrdma_xprt *r_xprt)
+{
+        struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
+        unsigned int inline_size, pages;
+
+        inline_size = min_t(unsigned int,
+                            cdata->inline_wsize, cdata->inline_rsize);
+        inline_size -= RPCRDMA_HDRLEN_MIN;
+        pages = inline_size / sizeof(struct rpcrdma_segment);
+        return pages << PAGE_SHIFT;
+}
+
+static size_t
+rpcrdma_mr_max_payload(struct rpcrdma_xprt *r_xprt)
+{
+        return RPCRDMA_MAX_DATA_SEGS << PAGE_SHIFT;
+}
+
+size_t
+rpcrdma_max_payload(struct rpcrdma_xprt *r_xprt)
+{
+        size_t result;
+
+        switch (r_xprt->rx_ia.ri_memreg_strategy) {
+        case RPCRDMA_ALLPHYSICAL:
+                result = rpcrdma_physical_max_payload(r_xprt);
+                break;
+        default:
+                result = rpcrdma_mr_max_payload(r_xprt);
+        }
+        return result;
+}
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 97ca516ec619..f3d86b24a4af 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -348,6 +348,7 @@ void rpcrdma_reply_handler(struct rpcrdma_rep *);
  * RPC/RDMA protocol calls - xprtrdma/rpc_rdma.c
  */
 int rpcrdma_marshal_req(struct rpc_rqst *);
+size_t rpcrdma_max_payload(struct rpcrdma_xprt *);
 
 /* Temporary NFS request map cache. Created in svc_rdma.c  */
 extern struct kmem_cache *svc_rdma_map_cachep;