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Commit 5457ced0 authored by Chuck Lever's avatar Chuck Lever Committed by Anna Schumaker
Browse files

xprtrdma: Account for RPC/RDMA header size when deciding to inline 



When the size of the RPC message is near the inline threshold (1KB),
the client would allow messages to be sent that were a few bytes too
large.

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.

The two server implementations I test with (Linux and Solaris) use
receive buffers that are larger than the client’s inline threshold.
Thus so far this has been benign, observed only by code inspection.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Reviewed-by: default avatarDevesh Sharma <devesh.sharma@avagotech.com>
Tested-by: default avatarDevesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent b3221d6a

net/sunrpc/xprtrdma/rpc_rdma.c

+27 −2
Original line number Diff line number Diff line
@@ -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.

 *
@@ -409,7 +434,7 @@ 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;
@@ -432,7 +457,7 @@ 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;