/* * Copyright (c) 2015 Oracle. All rights reserved. * * Support for backward direction RPCs on RPC/RDMA. */ #include <linux/module.h> #include <linux/sunrpc/xprt.h> #include <linux/sunrpc/svc.h> #include <linux/sunrpc/svc_xprt.h> #include "xprt_rdma.h" #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) # define RPCDBG_FACILITY RPCDBG_TRANS #endif #undef RPCRDMA_BACKCHANNEL_DEBUG static void rpcrdma_bc_free_rqst(struct rpcrdma_xprt *r_xprt, struct rpc_rqst *rqst) { struct rpcrdma_buffer *buf = &r_xprt->rx_buf; struct rpcrdma_req *req = rpcr_to_rdmar(rqst); spin_lock(&buf->rb_reqslock); list_del(&req->rl_all); spin_unlock(&buf->rb_reqslock); rpcrdma_destroy_req(req); kfree(rqst); } static int rpcrdma_bc_setup_rqst(struct rpcrdma_xprt *r_xprt, struct rpc_rqst *rqst) { struct rpcrdma_regbuf *rb; struct rpcrdma_req *req; size_t size; req = rpcrdma_create_req(r_xprt); if (IS_ERR(req)) return PTR_ERR(req); req->rl_backchannel = true; rb = rpcrdma_alloc_regbuf(RPCRDMA_HDRBUF_SIZE, DMA_TO_DEVICE, GFP_KERNEL); if (IS_ERR(rb)) goto out_fail; req->rl_rdmabuf = rb; size = r_xprt->rx_data.inline_rsize; rb = rpcrdma_alloc_regbuf(size, DMA_TO_DEVICE, GFP_KERNEL); if (IS_ERR(rb)) goto out_fail; req->rl_sendbuf = rb; xdr_buf_init(&rqst->rq_snd_buf, rb->rg_base, min_t(size_t, size, PAGE_SIZE)); rpcrdma_set_xprtdata(rqst, req); return 0; out_fail: rpcrdma_bc_free_rqst(r_xprt, rqst); return -ENOMEM; } /* Allocate and add receive buffers to the rpcrdma_buffer's * existing list of rep's. These are released when the * transport is destroyed. */ static int rpcrdma_bc_setup_reps(struct rpcrdma_xprt *r_xprt, unsigned int count) { struct rpcrdma_rep *rep; int rc = 0; while (count--) { rep = rpcrdma_create_rep(r_xprt); if (IS_ERR(rep)) { pr_err("RPC: %s: reply buffer alloc failed\n", __func__); rc = PTR_ERR(rep); break; } rpcrdma_recv_buffer_put(rep); } return rc; } /** * 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); struct rpcrdma_buffer *buffer = &r_xprt->rx_buf; struct rpc_rqst *rqst; unsigned int i; 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; for (i = 0; i < (reqs << 1); i++) { rqst = kzalloc(sizeof(*rqst), GFP_KERNEL); if (!rqst) { pr_err("RPC: %s: Failed to create bc rpc_rqst\n", __func__); goto out_free; } dprintk("RPC: %s: new rqst %p\n", __func__, rqst); rqst->rq_xprt = &r_xprt->rx_xprt; INIT_LIST_HEAD(&rqst->rq_list); INIT_LIST_HEAD(&rqst->rq_bc_list); if (rpcrdma_bc_setup_rqst(r_xprt, rqst)) goto out_free; spin_lock_bh(&xprt->bc_pa_lock); list_add(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); spin_unlock_bh(&xprt->bc_pa_lock); } rc = rpcrdma_bc_setup_reps(r_xprt, reqs); if (rc) goto out_free; rc = rpcrdma_ep_post_extra_recv(r_xprt, reqs); if (rc) goto out_free; buffer->rb_bc_srv_max_requests = reqs; request_module("svcrdma"); 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_up - Create transport endpoint for backchannel service * @serv: server endpoint * @net: network namespace * * The "xprt" is an implied argument: it supplies the name of the * backchannel transport class. * * Returns zero on success, negative errno on failure */ int xprt_rdma_bc_up(struct svc_serv *serv, struct net *net) { int ret; ret = svc_create_xprt(serv, "rdma-bc", net, PF_INET, 0, 0); if (ret < 0) return ret; return 0; } /** * 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; } /** * rpcrdma_bc_marshal_reply - Send backwards direction reply * @rqst: buffer containing RPC reply data * * Returns zero on success. */ int rpcrdma_bc_marshal_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); struct rpcrdma_msg *headerp; headerp = rdmab_to_msg(req->rl_rdmabuf); headerp->rm_xid = rqst->rq_xid; headerp->rm_vers = rpcrdma_version; headerp->rm_credit = cpu_to_be32(r_xprt->rx_buf.rb_bc_srv_max_requests); headerp->rm_type = rdma_msg; headerp->rm_body.rm_chunks[0] = xdr_zero; headerp->rm_body.rm_chunks[1] = xdr_zero; headerp->rm_body.rm_chunks[2] = xdr_zero; if (!rpcrdma_prepare_send_sges(&r_xprt->rx_ia, req, RPCRDMA_HDRLEN_MIN, &rqst->rq_snd_buf, rpcrdma_noch)) return -EIO; return 0; } /** * 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 rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); struct rpc_rqst *rqst, *tmp; spin_lock_bh(&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_bh(&xprt->bc_pa_lock); rpcrdma_bc_free_rqst(r_xprt, rqst); spin_lock_bh(&xprt->bc_pa_lock); } spin_unlock_bh(&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 rpc_xprt *xprt = rqst->rq_xprt; dprintk("RPC: %s: freeing rqst %p (req %p)\n", __func__, rqst, rpcr_to_rdmar(rqst)); smp_mb__before_atomic(); WARN_ON_ONCE(!test_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state)); clear_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); smp_mb__after_atomic(); spin_lock_bh(&xprt->bc_pa_lock); list_add_tail(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); spin_unlock_bh(&xprt->bc_pa_lock); } /** * rpcrdma_bc_receive_call - Handle a backward direction call * @xprt: transport receiving the call * @rep: receive buffer containing the call * * Called in the RPC reply handler, which runs in a tasklet. * Be quick about it. * * 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 rpcrdma_msg *headerp; struct svc_serv *bc_serv; struct rpcrdma_req *req; struct rpc_rqst *rqst; struct xdr_buf *buf; size_t size; __be32 *p; headerp = rdmab_to_msg(rep->rr_rdmabuf); #ifdef RPCRDMA_BACKCHANNEL_DEBUG pr_info("RPC: %s: callback XID %08x, length=%u\n", __func__, be32_to_cpu(headerp->rm_xid), rep->rr_len); pr_info("RPC: %s: %*ph\n", __func__, rep->rr_len, headerp); #endif /* Sanity check: * Need at least enough bytes for RPC/RDMA header, as code * here references the header fields by array offset. Also, * backward calls are always inline, so ensure there * are some bytes beyond the RPC/RDMA header. */ if (rep->rr_len < RPCRDMA_HDRLEN_MIN + 24) goto out_short; p = (__be32 *)((unsigned char *)headerp + RPCRDMA_HDRLEN_MIN); size = rep->rr_len - RPCRDMA_HDRLEN_MIN; /* 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); dprintk("RPC: %s: using rqst %p\n", __func__, rqst); /* Prepare rqst */ rqst->rq_reply_bytes_recvd = 0; rqst->rq_bytes_sent = 0; rqst->rq_xid = headerp->rm_xid; rqst->rq_private_buf.len = size; set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); 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 can be reposted after the server is done * parsing it but just before sending the backward * direction reply. */ req = rpcr_to_rdmar(rqst); dprintk("RPC: %s: attaching rep %p to req %p\n", __func__, rep, req); req->rl_reply = rep; /* Defeat the retransmit detection logic in send_request */ req->rl_connect_cookie = 0; /* 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_disconnect_done(xprt); /* This receive buffer gets reposted automatically * when the connection is re-established. */ return; out_short: pr_warn("RPC/RDMA short backward direction call\n"); if (rpcrdma_ep_post_recv(&r_xprt->rx_ia, rep)) xprt_disconnect_done(xprt); else pr_warn("RPC: %s: reposting rep %p\n", __func__, rep); }