// SPDX-License-Identifier: GPL-2.0 /* * Copyright (c) 2015 Oracle. All rights reserved. * * Support for backward direction RPCs on RPC/RDMA. */ #include #include #include #include #include "xprt_rdma.h" #include #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) # define RPCDBG_FACILITY RPCDBG_TRANS #endif #undef RPCRDMA_BACKCHANNEL_DEBUG static int rpcrdma_bc_setup_reqs(struct rpcrdma_xprt *r_xprt, unsigned int count) { struct rpc_xprt *xprt = &r_xprt->rx_xprt; struct rpcrdma_req *req; struct rpc_rqst *rqst; unsigned int i; for (i = 0; i < (count << 1); i++) { size_t size; size = min_t(size_t, r_xprt->rx_data.inline_rsize, PAGE_SIZE); req = rpcrdma_req_create(r_xprt, size, GFP_KERNEL); if (!req) return -ENOMEM; rqst = &req->rl_slot; rqst->rq_xprt = xprt; INIT_LIST_HEAD(&rqst->rq_bc_list); __set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); spin_lock(&xprt->bc_pa_lock); list_add(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); spin_unlock(&xprt->bc_pa_lock); xdr_buf_init(&rqst->rq_snd_buf, rdmab_data(req->rl_sendbuf), size); } return 0; } /** * 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) { struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); int rc; /* The backchannel reply path returns each rpc_rqst to the * bc_pa_list _after_ the reply is sent. If the server is * faster than the client, it can send another backward * direction request before the rpc_rqst is returned to the * list. The client rejects the request in this case. * * Twice as many rpc_rqsts are prepared to ensure there is * always an rpc_rqst available as soon as a reply is sent. */ if (reqs > RPCRDMA_BACKWARD_WRS >> 1) goto out_err; rc = rpcrdma_bc_setup_reqs(r_xprt, reqs); if (rc) goto out_free; r_xprt->rx_buf.rb_bc_srv_max_requests = reqs; trace_xprtrdma_cb_setup(r_xprt, reqs); return 0; out_free: xprt_rdma_bc_destroy(xprt, reqs); out_err: pr_err("RPC: %s: setup backchannel transport failed\n", __func__); return -ENOMEM; } /** * 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) { struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data; size_t maxmsg; maxmsg = min_t(unsigned int, cdata->inline_rsize, cdata->inline_wsize); maxmsg = min_t(unsigned int, maxmsg, PAGE_SIZE); return maxmsg - RPCRDMA_HDRLEN_MIN; } static int rpcrdma_bc_marshal_reply(struct rpc_rqst *rqst) { struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_xprt); struct rpcrdma_req *req = rpcr_to_rdmar(rqst); __be32 *p; rpcrdma_set_xdrlen(&req->rl_hdrbuf, 0); xdr_init_encode(&req->rl_stream, &req->rl_hdrbuf, rdmab_data(req->rl_rdmabuf), rqst); p = xdr_reserve_space(&req->rl_stream, 28); if (unlikely(!p)) return -EIO; *p++ = rqst->rq_xid; *p++ = rpcrdma_version; *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_srv_max_requests); *p++ = rdma_msg; *p++ = xdr_zero; *p++ = xdr_zero; *p = xdr_zero; if (rpcrdma_prepare_send_sges(r_xprt, req, RPCRDMA_HDRLEN_MIN, &rqst->rq_snd_buf, rpcrdma_noch)) return -EIO; trace_xprtrdma_cb_reply(rqst); return 0; } /** * 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) { struct rpc_xprt *xprt = rqst->rq_xprt; struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); struct rpcrdma_req *req = rpcr_to_rdmar(rqst); int rc; if (!xprt_connected(xprt)) return -ENOTCONN; if (!xprt_request_get_cong(xprt, rqst)) return -EBADSLT; rc = rpcrdma_bc_marshal_reply(rqst); if (rc < 0) goto failed_marshal; if (rpcrdma_ep_post(&r_xprt->rx_ia, &r_xprt->rx_ep, req)) goto drop_connection; return 0; failed_marshal: if (rc != -ENOTCONN) return rc; drop_connection: xprt_rdma_close(xprt); return -ENOTCONN; } /** * 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) { struct rpc_rqst *rqst, *tmp; spin_lock(&xprt->bc_pa_lock); list_for_each_entry_safe(rqst, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { list_del(&rqst->rq_bc_pa_list); spin_unlock(&xprt->bc_pa_lock); rpcrdma_req_destroy(rpcr_to_rdmar(rqst)); spin_lock(&xprt->bc_pa_lock); } spin_unlock(&xprt->bc_pa_lock); } /** * xprt_rdma_bc_free_rqst - Release a backchannel rqst * @rqst: request to release */ void xprt_rdma_bc_free_rqst(struct rpc_rqst *rqst) { struct rpcrdma_req *req = rpcr_to_rdmar(rqst); struct rpc_xprt *xprt = rqst->rq_xprt; rpcrdma_recv_buffer_put(req->rl_reply); req->rl_reply = NULL; spin_lock(&xprt->bc_pa_lock); list_add_tail(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); spin_unlock(&xprt->bc_pa_lock); } /** * rpcrdma_bc_receive_call - Handle a backward 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) { struct rpc_xprt *xprt = &r_xprt->rx_xprt; struct svc_serv *bc_serv; struct rpcrdma_req *req; struct rpc_rqst *rqst; struct xdr_buf *buf; size_t size; __be32 *p; p = xdr_inline_decode(&rep->rr_stream, 0); size = xdr_stream_remaining(&rep->rr_stream); #ifdef RPCRDMA_BACKCHANNEL_DEBUG pr_info("RPC: %s: callback XID %08x, length=%u\n", __func__, be32_to_cpup(p), size); pr_info("RPC: %s: %*ph\n", __func__, size, p); #endif /* Grab a free bc rqst */ spin_lock(&xprt->bc_pa_lock); if (list_empty(&xprt->bc_pa_list)) { spin_unlock(&xprt->bc_pa_lock); goto out_overflow; } rqst = list_first_entry(&xprt->bc_pa_list, struct rpc_rqst, rq_bc_pa_list); list_del(&rqst->rq_bc_pa_list); spin_unlock(&xprt->bc_pa_lock); /* Prepare rqst */ rqst->rq_reply_bytes_recvd = 0; rqst->rq_xid = *p; rqst->rq_private_buf.len = size; buf = &rqst->rq_rcv_buf; memset(buf, 0, sizeof(*buf)); buf->head[0].iov_base = p; buf->head[0].iov_len = size; buf->len = size; /* The receive buffer has to be hooked to the rpcrdma_req * so that it is not released while the req is pointing * to its buffer, and so that it can be reposted after * the Upper Layer is done decoding it. */ req = rpcr_to_rdmar(rqst); req->rl_reply = rep; trace_xprtrdma_cb_call(rqst); /* Queue rqst for ULP's callback service */ bc_serv = xprt->bc_serv; spin_lock(&bc_serv->sv_cb_lock); list_add(&rqst->rq_bc_list, &bc_serv->sv_cb_list); spin_unlock(&bc_serv->sv_cb_lock); wake_up(&bc_serv->sv_cb_waitq); r_xprt->rx_stats.bcall_count++; return; out_overflow: pr_warn("RPC/RDMA backchannel overflow\n"); xprt_force_disconnect(xprt); /* This receive buffer gets reposted automatically * when the connection is re-established. */ return; }