xprtrdma: Add a "max_payload" op for each memreg mode

The max_payload computation is generalized to ensure that the
payload maximum is the lesser of RPC_MAX_DATA_SEGS and the number of
data segments that can be transmitted in an inline buffer.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Tested-by: Devesh Sharma <Devesh.Sharma@Emulex.Com>
Tested-by: Meghana Cheripady <Meghana.Cheripady@Emulex.Com>
Tested-by: Veeresh U. Kokatnur <veereshuk@chelsio.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

1 files changed, 15 insertions, 34 deletions

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index c3319e12551c..da55cda30568 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -2212,43 +2212,24 @@ rpcrdma_ep_post_recv(struct rpcrdma_ia *ia,
 	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.
+/* How many chunk list items fit within our inline buffers?
  */
-static size_t
-rpcrdma_physical_max_payload(struct rpcrdma_xprt *r_xprt)
+unsigned int
+rpcrdma_max_segments(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;
-}
+	int bytes, segments;
 
-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);
+	bytes = min_t(unsigned int, cdata->inline_wsize, cdata->inline_rsize);
+	bytes -= RPCRDMA_HDRLEN_MIN;
+	if (bytes < sizeof(struct rpcrdma_segment) * 2) {
+		pr_warn("RPC:       %s: inline threshold too small\n",
+			__func__);
+		return 0;
 	}
-	return result;
+
+	segments = 1 << (fls(bytes / sizeof(struct rpcrdma_segment)) - 1);
+	dprintk("RPC:       %s: max chunk list size = %d segments\n",
+		__func__, segments);
+	return segments;
 }