1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2015 Oracle. All rights reserved. 4 * 5 * Support for backward direction RPCs on RPC/RDMA. 6 */ 7 8 #include <linux/module.h> 9 #include <linux/sunrpc/xprt.h> 10 #include <linux/sunrpc/svc.h> 11 #include <linux/sunrpc/svc_xprt.h> 12 13 #include "xprt_rdma.h" 14 15 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) 16 # define RPCDBG_FACILITY RPCDBG_TRANS 17 #endif 18 19 #undef RPCRDMA_BACKCHANNEL_DEBUG 20 21 static void rpcrdma_bc_free_rqst(struct rpcrdma_xprt *r_xprt, 22 struct rpc_rqst *rqst) 23 { 24 struct rpcrdma_buffer *buf = &r_xprt->rx_buf; 25 struct rpcrdma_req *req = rpcr_to_rdmar(rqst); 26 27 spin_lock(&buf->rb_reqslock); 28 list_del(&req->rl_all); 29 spin_unlock(&buf->rb_reqslock); 30 31 rpcrdma_destroy_req(req); 32 33 kfree(rqst); 34 } 35 36 static int rpcrdma_bc_setup_rqst(struct rpcrdma_xprt *r_xprt, 37 struct rpc_rqst *rqst) 38 { 39 struct rpcrdma_regbuf *rb; 40 struct rpcrdma_req *req; 41 size_t size; 42 43 req = rpcrdma_create_req(r_xprt); 44 if (IS_ERR(req)) 45 return PTR_ERR(req); 46 47 size = r_xprt->rx_data.inline_rsize; 48 rb = rpcrdma_alloc_regbuf(size, DMA_TO_DEVICE, GFP_KERNEL); 49 if (IS_ERR(rb)) 50 goto out_fail; 51 req->rl_sendbuf = rb; 52 xdr_buf_init(&rqst->rq_snd_buf, rb->rg_base, 53 min_t(size_t, size, PAGE_SIZE)); 54 rpcrdma_set_xprtdata(rqst, req); 55 return 0; 56 57 out_fail: 58 rpcrdma_bc_free_rqst(r_xprt, rqst); 59 return -ENOMEM; 60 } 61 62 /* Allocate and add receive buffers to the rpcrdma_buffer's 63 * existing list of rep's. These are released when the 64 * transport is destroyed. 65 */ 66 static int rpcrdma_bc_setup_reps(struct rpcrdma_xprt *r_xprt, 67 unsigned int count) 68 { 69 int rc = 0; 70 71 while (count--) { 72 rc = rpcrdma_create_rep(r_xprt); 73 if (rc) 74 break; 75 } 76 return rc; 77 } 78 79 /** 80 * xprt_rdma_bc_setup - Pre-allocate resources for handling backchannel requests 81 * @xprt: transport associated with these backchannel resources 82 * @reqs: number of concurrent incoming requests to expect 83 * 84 * Returns 0 on success; otherwise a negative errno 85 */ 86 int xprt_rdma_bc_setup(struct rpc_xprt *xprt, unsigned int reqs) 87 { 88 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 89 struct rpcrdma_buffer *buffer = &r_xprt->rx_buf; 90 struct rpc_rqst *rqst; 91 unsigned int i; 92 int rc; 93 94 /* The backchannel reply path returns each rpc_rqst to the 95 * bc_pa_list _after_ the reply is sent. If the server is 96 * faster than the client, it can send another backward 97 * direction request before the rpc_rqst is returned to the 98 * list. The client rejects the request in this case. 99 * 100 * Twice as many rpc_rqsts are prepared to ensure there is 101 * always an rpc_rqst available as soon as a reply is sent. 102 */ 103 if (reqs > RPCRDMA_BACKWARD_WRS >> 1) 104 goto out_err; 105 106 for (i = 0; i < (reqs << 1); i++) { 107 rqst = kzalloc(sizeof(*rqst), GFP_KERNEL); 108 if (!rqst) 109 goto out_free; 110 111 dprintk("RPC: %s: new rqst %p\n", __func__, rqst); 112 113 rqst->rq_xprt = &r_xprt->rx_xprt; 114 INIT_LIST_HEAD(&rqst->rq_list); 115 INIT_LIST_HEAD(&rqst->rq_bc_list); 116 __set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); 117 118 if (rpcrdma_bc_setup_rqst(r_xprt, rqst)) 119 goto out_free; 120 121 spin_lock_bh(&xprt->bc_pa_lock); 122 list_add(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); 123 spin_unlock_bh(&xprt->bc_pa_lock); 124 } 125 126 rc = rpcrdma_bc_setup_reps(r_xprt, reqs); 127 if (rc) 128 goto out_free; 129 130 rc = rpcrdma_ep_post_extra_recv(r_xprt, reqs); 131 if (rc) 132 goto out_free; 133 134 buffer->rb_bc_srv_max_requests = reqs; 135 request_module("svcrdma"); 136 trace_xprtrdma_cb_setup(r_xprt, reqs); 137 return 0; 138 139 out_free: 140 xprt_rdma_bc_destroy(xprt, reqs); 141 142 out_err: 143 pr_err("RPC: %s: setup backchannel transport failed\n", __func__); 144 return -ENOMEM; 145 } 146 147 /** 148 * xprt_rdma_bc_up - Create transport endpoint for backchannel service 149 * @serv: server endpoint 150 * @net: network namespace 151 * 152 * The "xprt" is an implied argument: it supplies the name of the 153 * backchannel transport class. 154 * 155 * Returns zero on success, negative errno on failure 156 */ 157 int xprt_rdma_bc_up(struct svc_serv *serv, struct net *net) 158 { 159 int ret; 160 161 ret = svc_create_xprt(serv, "rdma-bc", net, PF_INET, 0, 0); 162 if (ret < 0) 163 return ret; 164 return 0; 165 } 166 167 /** 168 * xprt_rdma_bc_maxpayload - Return maximum backchannel message size 169 * @xprt: transport 170 * 171 * Returns maximum size, in bytes, of a backchannel message 172 */ 173 size_t xprt_rdma_bc_maxpayload(struct rpc_xprt *xprt) 174 { 175 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 176 struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data; 177 size_t maxmsg; 178 179 maxmsg = min_t(unsigned int, cdata->inline_rsize, cdata->inline_wsize); 180 maxmsg = min_t(unsigned int, maxmsg, PAGE_SIZE); 181 return maxmsg - RPCRDMA_HDRLEN_MIN; 182 } 183 184 static int rpcrdma_bc_marshal_reply(struct rpc_rqst *rqst) 185 { 186 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_xprt); 187 struct rpcrdma_req *req = rpcr_to_rdmar(rqst); 188 __be32 *p; 189 190 rpcrdma_set_xdrlen(&req->rl_hdrbuf, 0); 191 xdr_init_encode(&req->rl_stream, &req->rl_hdrbuf, 192 req->rl_rdmabuf->rg_base); 193 194 p = xdr_reserve_space(&req->rl_stream, 28); 195 if (unlikely(!p)) 196 return -EIO; 197 *p++ = rqst->rq_xid; 198 *p++ = rpcrdma_version; 199 *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_srv_max_requests); 200 *p++ = rdma_msg; 201 *p++ = xdr_zero; 202 *p++ = xdr_zero; 203 *p = xdr_zero; 204 205 if (rpcrdma_prepare_send_sges(r_xprt, req, RPCRDMA_HDRLEN_MIN, 206 &rqst->rq_snd_buf, rpcrdma_noch)) 207 return -EIO; 208 209 trace_xprtrdma_cb_reply(rqst); 210 return 0; 211 } 212 213 /** 214 * xprt_rdma_bc_send_reply - marshal and send a backchannel reply 215 * @rqst: RPC rqst with a backchannel RPC reply in rq_snd_buf 216 * 217 * Caller holds the transport's write lock. 218 * 219 * Returns: 220 * %0 if the RPC message has been sent 221 * %-ENOTCONN if the caller should reconnect and call again 222 * %-EIO if a permanent error occurred and the request was not 223 * sent. Do not try to send this message again. 224 */ 225 int xprt_rdma_bc_send_reply(struct rpc_rqst *rqst) 226 { 227 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_xprt); 228 struct rpcrdma_req *req = rpcr_to_rdmar(rqst); 229 int rc; 230 231 if (!xprt_connected(rqst->rq_xprt)) 232 goto drop_connection; 233 234 rc = rpcrdma_bc_marshal_reply(rqst); 235 if (rc < 0) 236 goto failed_marshal; 237 238 if (rpcrdma_ep_post(&r_xprt->rx_ia, &r_xprt->rx_ep, req)) 239 goto drop_connection; 240 return 0; 241 242 failed_marshal: 243 if (rc != -ENOTCONN) 244 return rc; 245 drop_connection: 246 xprt_disconnect_done(rqst->rq_xprt); 247 return -ENOTCONN; 248 } 249 250 /** 251 * xprt_rdma_bc_destroy - Release resources for handling backchannel requests 252 * @xprt: transport associated with these backchannel resources 253 * @reqs: number of incoming requests to destroy; ignored 254 */ 255 void xprt_rdma_bc_destroy(struct rpc_xprt *xprt, unsigned int reqs) 256 { 257 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 258 struct rpc_rqst *rqst, *tmp; 259 260 spin_lock_bh(&xprt->bc_pa_lock); 261 list_for_each_entry_safe(rqst, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { 262 list_del(&rqst->rq_bc_pa_list); 263 spin_unlock_bh(&xprt->bc_pa_lock); 264 265 rpcrdma_bc_free_rqst(r_xprt, rqst); 266 267 spin_lock_bh(&xprt->bc_pa_lock); 268 } 269 spin_unlock_bh(&xprt->bc_pa_lock); 270 } 271 272 /** 273 * xprt_rdma_bc_free_rqst - Release a backchannel rqst 274 * @rqst: request to release 275 */ 276 void xprt_rdma_bc_free_rqst(struct rpc_rqst *rqst) 277 { 278 struct rpc_xprt *xprt = rqst->rq_xprt; 279 280 dprintk("RPC: %s: freeing rqst %p (req %p)\n", 281 __func__, rqst, rpcr_to_rdmar(rqst)); 282 283 spin_lock_bh(&xprt->bc_pa_lock); 284 list_add_tail(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); 285 spin_unlock_bh(&xprt->bc_pa_lock); 286 } 287 288 /** 289 * rpcrdma_bc_receive_call - Handle a backward direction call 290 * @r_xprt: transport receiving the call 291 * @rep: receive buffer containing the call 292 * 293 * Operational assumptions: 294 * o Backchannel credits are ignored, just as the NFS server 295 * forechannel currently does 296 * o The ULP manages a replay cache (eg, NFSv4.1 sessions). 297 * No replay detection is done at the transport level 298 */ 299 void rpcrdma_bc_receive_call(struct rpcrdma_xprt *r_xprt, 300 struct rpcrdma_rep *rep) 301 { 302 struct rpc_xprt *xprt = &r_xprt->rx_xprt; 303 struct svc_serv *bc_serv; 304 struct rpcrdma_req *req; 305 struct rpc_rqst *rqst; 306 struct xdr_buf *buf; 307 size_t size; 308 __be32 *p; 309 310 p = xdr_inline_decode(&rep->rr_stream, 0); 311 size = xdr_stream_remaining(&rep->rr_stream); 312 313 #ifdef RPCRDMA_BACKCHANNEL_DEBUG 314 pr_info("RPC: %s: callback XID %08x, length=%u\n", 315 __func__, be32_to_cpup(p), size); 316 pr_info("RPC: %s: %*ph\n", __func__, size, p); 317 #endif 318 319 /* Grab a free bc rqst */ 320 spin_lock(&xprt->bc_pa_lock); 321 if (list_empty(&xprt->bc_pa_list)) { 322 spin_unlock(&xprt->bc_pa_lock); 323 goto out_overflow; 324 } 325 rqst = list_first_entry(&xprt->bc_pa_list, 326 struct rpc_rqst, rq_bc_pa_list); 327 list_del(&rqst->rq_bc_pa_list); 328 spin_unlock(&xprt->bc_pa_lock); 329 330 /* Prepare rqst */ 331 rqst->rq_reply_bytes_recvd = 0; 332 rqst->rq_bytes_sent = 0; 333 rqst->rq_xid = *p; 334 335 rqst->rq_private_buf.len = size; 336 337 buf = &rqst->rq_rcv_buf; 338 memset(buf, 0, sizeof(*buf)); 339 buf->head[0].iov_base = p; 340 buf->head[0].iov_len = size; 341 buf->len = size; 342 343 /* The receive buffer has to be hooked to the rpcrdma_req 344 * so that it is not released while the req is pointing 345 * to its buffer, and so that it can be reposted after 346 * the Upper Layer is done decoding it. 347 */ 348 req = rpcr_to_rdmar(rqst); 349 req->rl_reply = rep; 350 trace_xprtrdma_cb_call(rqst); 351 352 /* Queue rqst for ULP's callback service */ 353 bc_serv = xprt->bc_serv; 354 spin_lock(&bc_serv->sv_cb_lock); 355 list_add(&rqst->rq_bc_list, &bc_serv->sv_cb_list); 356 spin_unlock(&bc_serv->sv_cb_lock); 357 358 wake_up(&bc_serv->sv_cb_waitq); 359 360 r_xprt->rx_stats.bcall_count++; 361 return; 362 363 out_overflow: 364 pr_warn("RPC/RDMA backchannel overflow\n"); 365 xprt_disconnect_done(xprt); 366 /* This receive buffer gets reposted automatically 367 * when the connection is re-established. 368 */ 369 return; 370 } 371