linux/net/sunrpc/xprtrdma/backchannel.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2015-2020, Oracle and/or its affiliates.
 *
 * Support for reverse-direction RPCs on RPC/RDMA.
 */

#include <linux/sunrpc/xprt.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/svc_xprt.h>
#include <linux/sunrpc/svc_rdma.h>

#include "xprt_rdma.h"
#include <trace/events/rpcrdma.h>

#undef RPCRDMA_BACKCHANNEL_DEBUG

/**
 * xprt_rdma_bc_setup - Pre-allocate resources for handling backchannel requests
 * @xprt: transport associated with these backchannel resources
 * @reqs: number of concurrent incoming requests to expect
 *
 * Returns 0 on success; otherwise a negative errno
 */
int xprt_rdma_bc_setup(struct rpc_xprt *xprt, unsigned int reqs)
{ … }

/**
 * xprt_rdma_bc_maxpayload - Return maximum backchannel message size
 * @xprt: transport
 *
 * Returns maximum size, in bytes, of a backchannel message
 */
size_t xprt_rdma_bc_maxpayload(struct rpc_xprt *xprt)
{ … }

unsigned int xprt_rdma_bc_max_slots(struct rpc_xprt *xprt)
{ … }

static int rpcrdma_bc_marshal_reply(struct rpc_rqst *rqst)
{ … }

/**
 * xprt_rdma_bc_send_reply - marshal and send a backchannel reply
 * @rqst: RPC rqst with a backchannel RPC reply in rq_snd_buf
 *
 * Caller holds the transport's write lock.
 *
 * Returns:
 *	%0 if the RPC message has been sent
 *	%-ENOTCONN if the caller should reconnect and call again
 *	%-EIO if a permanent error occurred and the request was not
 *		sent. Do not try to send this message again.
 */
int xprt_rdma_bc_send_reply(struct rpc_rqst *rqst)
{ … }

/**
 * xprt_rdma_bc_destroy - Release resources for handling backchannel requests
 * @xprt: transport associated with these backchannel resources
 * @reqs: number of incoming requests to destroy; ignored
 */
void xprt_rdma_bc_destroy(struct rpc_xprt *xprt, unsigned int reqs)
{ … }

/**
 * xprt_rdma_bc_free_rqst - Release a backchannel rqst
 * @rqst: request to release
 */
void xprt_rdma_bc_free_rqst(struct rpc_rqst *rqst)
{ … }

static struct rpc_rqst *rpcrdma_bc_rqst_get(struct rpcrdma_xprt *r_xprt)
{ … }

/**
 * rpcrdma_bc_receive_call - Handle a reverse-direction Call
 * @r_xprt: transport receiving the call
 * @rep: receive buffer containing the call
 *
 * Operational assumptions:
 *    o Backchannel credits are ignored, just as the NFS server
 *      forechannel currently does
 *    o The ULP manages a replay cache (eg, NFSv4.1 sessions).
 *      No replay detection is done at the transport level
 */
void rpcrdma_bc_receive_call(struct rpcrdma_xprt *r_xprt,
			     struct rpcrdma_rep *rep)
{ … }