[PATCH v1 05/12] xprtrdma: Account for RPC/RDMA header size when deciding to inline

Chuck Lever
2015-07-09T20:42:27Z

When marshaling RPC/RDMA requests, ensure the combined size of
RPC/RDMA header and RPC header do not exceed the inline threshold.
Endpoints typically reject RPC/RDMA messages that exceed the size
of their receive buffers.

Signed-off-by: Chuck Lever <chuck.lever-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
---
net/sunrpc/xprtrdma/rpc_rdma.c | 29 +++++++++++++++++++++++++++--
1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 84ea37d..8cf9402 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -71,6 +71,31 @@ static const char transfertypes[][12] = {
};
#endif

+/* The client can send a request inline as long as the RPCRDMA header
+ * plus the RPC call fit under the transport's inline limit. If the
+ * combined call message size exceeds that limit, the client must use
+ * the read chunk list for this operation.
+ */
+static bool rpcrdma_args_inline(struct rpc_rqst *rqst)
+{
+ unsigned int callsize = RPCRDMA_HDRLEN_MIN + rqst->rq_snd_buf.len;
+
+ return callsize <= RPCRDMA_INLINE_WRITE_THRESHOLD(rqst);
+}
+
+/* The client can’t know how large the actual reply will be. Thus it
+ * plans for the largest possible reply for that particular ULP
+ * operation. If the maximum combined reply message size exceeds that
+ * limit, the client must provide a write list or a reply chunk for
+ * this request.
+ */
+static bool rpcrdma_results_inline(struct rpc_rqst *rqst)
+{
+ unsigned int repsize = RPCRDMA_HDRLEN_MIN + rqst->rq_rcv_buf.buflen;
+
+ return repsize <= RPCRDMA_INLINE_READ_THRESHOLD(rqst);
+}
+
/*
* Chunk assembly from upper layer xdr_buf.
*
@@ -418,7 +443,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
* a READ, then use write chunks to separate the file data
* into pages; otherwise use reply chunks.
*/
- if (rqst->rq_rcv_buf.buflen <= RPCRDMA_INLINE_READ_THRESHOLD(rqst))
+ if (rpcrdma_results_inline(rqst))
wtype = rpcrdma_noch;
else if (rqst->rq_rcv_buf.page_len == 0)
wtype = rpcrdma_replych;
@@ -441,7 +466,7 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
* implies the op is a write.
* TBD check NFSv4 setacl
*/
- if (rqst->rq_snd_buf.len <= RPCRDMA_INLINE_WRITE_THRESHOLD(rqst))
+ if (rpcrdma_args_inline(rqst))
rtype = rpcrdma_noch;
else if (rqst->rq_snd_buf.page_len == 0)
rtype = rpcrdma_areadch;

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