1 /* 2 * Copyright (c) 2015 Oracle. All rights reserved. 3 * 4 * Support for backward direction RPCs on RPC/RDMA. 5 */ 6 7 #include <linux/module.h> 8 #include <linux/sunrpc/xprt.h> 9 #include <linux/sunrpc/svc.h> 10 #include <linux/sunrpc/svc_xprt.h> 11 12 #include "xprt_rdma.h" 13 14 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) 15 # define RPCDBG_FACILITY RPCDBG_TRANS 16 #endif 17 18 #undef RPCRDMA_BACKCHANNEL_DEBUG 19 20 static void rpcrdma_bc_free_rqst(struct rpcrdma_xprt *r_xprt, 21 struct rpc_rqst *rqst) 22 { 23 struct rpcrdma_buffer *buf = &r_xprt->rx_buf; 24 struct rpcrdma_req *req = rpcr_to_rdmar(rqst); 25 26 spin_lock(&buf->rb_reqslock); 27 list_del(&req->rl_all); 28 spin_unlock(&buf->rb_reqslock); 29 30 rpcrdma_destroy_req(req); 31 32 kfree(rqst); 33 } 34 35 static int rpcrdma_bc_setup_rqst(struct rpcrdma_xprt *r_xprt, 36 struct rpc_rqst *rqst) 37 { 38 struct rpcrdma_regbuf *rb; 39 struct rpcrdma_req *req; 40 size_t size; 41 42 req = rpcrdma_create_req(r_xprt); 43 if (IS_ERR(req)) 44 return PTR_ERR(req); 45 req->rl_backchannel = true; 46 47 rb = rpcrdma_alloc_regbuf(RPCRDMA_HDRBUF_SIZE, 48 DMA_TO_DEVICE, GFP_KERNEL); 49 if (IS_ERR(rb)) 50 goto out_fail; 51 req->rl_rdmabuf = rb; 52 53 size = r_xprt->rx_data.inline_rsize; 54 rb = rpcrdma_alloc_regbuf(size, DMA_TO_DEVICE, GFP_KERNEL); 55 if (IS_ERR(rb)) 56 goto out_fail; 57 req->rl_sendbuf = rb; 58 xdr_buf_init(&rqst->rq_snd_buf, rb->rg_base, 59 min_t(size_t, size, PAGE_SIZE)); 60 rpcrdma_set_xprtdata(rqst, req); 61 return 0; 62 63 out_fail: 64 rpcrdma_bc_free_rqst(r_xprt, rqst); 65 return -ENOMEM; 66 } 67 68 /* Allocate and add receive buffers to the rpcrdma_buffer's 69 * existing list of rep's. These are released when the 70 * transport is destroyed. 71 */ 72 static int rpcrdma_bc_setup_reps(struct rpcrdma_xprt *r_xprt, 73 unsigned int count) 74 { 75 struct rpcrdma_rep *rep; 76 int rc = 0; 77 78 while (count--) { 79 rep = rpcrdma_create_rep(r_xprt); 80 if (IS_ERR(rep)) { 81 pr_err("RPC: %s: reply buffer alloc failed\n", 82 __func__); 83 rc = PTR_ERR(rep); 84 break; 85 } 86 87 rpcrdma_recv_buffer_put(rep); 88 } 89 90 return rc; 91 } 92 93 /** 94 * xprt_rdma_bc_setup - Pre-allocate resources for handling backchannel requests 95 * @xprt: transport associated with these backchannel resources 96 * @reqs: number of concurrent incoming requests to expect 97 * 98 * Returns 0 on success; otherwise a negative errno 99 */ 100 int xprt_rdma_bc_setup(struct rpc_xprt *xprt, unsigned int reqs) 101 { 102 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 103 struct rpcrdma_buffer *buffer = &r_xprt->rx_buf; 104 struct rpc_rqst *rqst; 105 unsigned int i; 106 int rc; 107 108 /* The backchannel reply path returns each rpc_rqst to the 109 * bc_pa_list _after_ the reply is sent. If the server is 110 * faster than the client, it can send another backward 111 * direction request before the rpc_rqst is returned to the 112 * list. The client rejects the request in this case. 113 * 114 * Twice as many rpc_rqsts are prepared to ensure there is 115 * always an rpc_rqst available as soon as a reply is sent. 116 */ 117 if (reqs > RPCRDMA_BACKWARD_WRS >> 1) 118 goto out_err; 119 120 for (i = 0; i < (reqs << 1); i++) { 121 rqst = kzalloc(sizeof(*rqst), GFP_KERNEL); 122 if (!rqst) 123 goto out_free; 124 125 dprintk("RPC: %s: new rqst %p\n", __func__, rqst); 126 127 rqst->rq_xprt = &r_xprt->rx_xprt; 128 INIT_LIST_HEAD(&rqst->rq_list); 129 INIT_LIST_HEAD(&rqst->rq_bc_list); 130 131 if (rpcrdma_bc_setup_rqst(r_xprt, rqst)) 132 goto out_free; 133 134 spin_lock_bh(&xprt->bc_pa_lock); 135 list_add(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); 136 spin_unlock_bh(&xprt->bc_pa_lock); 137 } 138 139 rc = rpcrdma_bc_setup_reps(r_xprt, reqs); 140 if (rc) 141 goto out_free; 142 143 rc = rpcrdma_ep_post_extra_recv(r_xprt, reqs); 144 if (rc) 145 goto out_free; 146 147 buffer->rb_bc_srv_max_requests = reqs; 148 request_module("svcrdma"); 149 150 return 0; 151 152 out_free: 153 xprt_rdma_bc_destroy(xprt, reqs); 154 155 out_err: 156 pr_err("RPC: %s: setup backchannel transport failed\n", __func__); 157 return -ENOMEM; 158 } 159 160 /** 161 * xprt_rdma_bc_up - Create transport endpoint for backchannel service 162 * @serv: server endpoint 163 * @net: network namespace 164 * 165 * The "xprt" is an implied argument: it supplies the name of the 166 * backchannel transport class. 167 * 168 * Returns zero on success, negative errno on failure 169 */ 170 int xprt_rdma_bc_up(struct svc_serv *serv, struct net *net) 171 { 172 int ret; 173 174 ret = svc_create_xprt(serv, "rdma-bc", net, PF_INET, 0, 0); 175 if (ret < 0) 176 return ret; 177 return 0; 178 } 179 180 /** 181 * xprt_rdma_bc_maxpayload - Return maximum backchannel message size 182 * @xprt: transport 183 * 184 * Returns maximum size, in bytes, of a backchannel message 185 */ 186 size_t xprt_rdma_bc_maxpayload(struct rpc_xprt *xprt) 187 { 188 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 189 struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data; 190 size_t maxmsg; 191 192 maxmsg = min_t(unsigned int, cdata->inline_rsize, cdata->inline_wsize); 193 maxmsg = min_t(unsigned int, maxmsg, PAGE_SIZE); 194 return maxmsg - RPCRDMA_HDRLEN_MIN; 195 } 196 197 /** 198 * rpcrdma_bc_marshal_reply - Send backwards direction reply 199 * @rqst: buffer containing RPC reply data 200 * 201 * Returns zero on success. 202 */ 203 int rpcrdma_bc_marshal_reply(struct rpc_rqst *rqst) 204 { 205 struct rpc_xprt *xprt = rqst->rq_xprt; 206 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 207 struct rpcrdma_req *req = rpcr_to_rdmar(rqst); 208 struct rpcrdma_msg *headerp; 209 210 headerp = rdmab_to_msg(req->rl_rdmabuf); 211 headerp->rm_xid = rqst->rq_xid; 212 headerp->rm_vers = rpcrdma_version; 213 headerp->rm_credit = 214 cpu_to_be32(r_xprt->rx_buf.rb_bc_srv_max_requests); 215 headerp->rm_type = rdma_msg; 216 headerp->rm_body.rm_chunks[0] = xdr_zero; 217 headerp->rm_body.rm_chunks[1] = xdr_zero; 218 headerp->rm_body.rm_chunks[2] = xdr_zero; 219 220 if (!rpcrdma_prepare_send_sges(&r_xprt->rx_ia, req, RPCRDMA_HDRLEN_MIN, 221 &rqst->rq_snd_buf, rpcrdma_noch)) 222 return -EIO; 223 return 0; 224 } 225 226 /** 227 * xprt_rdma_bc_destroy - Release resources for handling backchannel requests 228 * @xprt: transport associated with these backchannel resources 229 * @reqs: number of incoming requests to destroy; ignored 230 */ 231 void xprt_rdma_bc_destroy(struct rpc_xprt *xprt, unsigned int reqs) 232 { 233 struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); 234 struct rpc_rqst *rqst, *tmp; 235 236 spin_lock_bh(&xprt->bc_pa_lock); 237 list_for_each_entry_safe(rqst, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { 238 list_del(&rqst->rq_bc_pa_list); 239 spin_unlock_bh(&xprt->bc_pa_lock); 240 241 rpcrdma_bc_free_rqst(r_xprt, rqst); 242 243 spin_lock_bh(&xprt->bc_pa_lock); 244 } 245 spin_unlock_bh(&xprt->bc_pa_lock); 246 } 247 248 /** 249 * xprt_rdma_bc_free_rqst - Release a backchannel rqst 250 * @rqst: request to release 251 */ 252 void xprt_rdma_bc_free_rqst(struct rpc_rqst *rqst) 253 { 254 struct rpc_xprt *xprt = rqst->rq_xprt; 255 256 dprintk("RPC: %s: freeing rqst %p (req %p)\n", 257 __func__, rqst, rpcr_to_rdmar(rqst)); 258 259 smp_mb__before_atomic(); 260 WARN_ON_ONCE(!test_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state)); 261 clear_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); 262 smp_mb__after_atomic(); 263 264 spin_lock_bh(&xprt->bc_pa_lock); 265 list_add_tail(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); 266 spin_unlock_bh(&xprt->bc_pa_lock); 267 } 268 269 /** 270 * rpcrdma_bc_receive_call - Handle a backward direction call 271 * @xprt: transport receiving the call 272 * @rep: receive buffer containing the call 273 * 274 * Called in the RPC reply handler, which runs in a tasklet. 275 * Be quick about it. 276 * 277 * Operational assumptions: 278 * o Backchannel credits are ignored, just as the NFS server 279 * forechannel currently does 280 * o The ULP manages a replay cache (eg, NFSv4.1 sessions). 281 * No replay detection is done at the transport level 282 */ 283 void rpcrdma_bc_receive_call(struct rpcrdma_xprt *r_xprt, 284 struct rpcrdma_rep *rep) 285 { 286 struct rpc_xprt *xprt = &r_xprt->rx_xprt; 287 struct rpcrdma_msg *headerp; 288 struct svc_serv *bc_serv; 289 struct rpcrdma_req *req; 290 struct rpc_rqst *rqst; 291 struct xdr_buf *buf; 292 size_t size; 293 __be32 *p; 294 295 headerp = rdmab_to_msg(rep->rr_rdmabuf); 296 #ifdef RPCRDMA_BACKCHANNEL_DEBUG 297 pr_info("RPC: %s: callback XID %08x, length=%u\n", 298 __func__, be32_to_cpu(headerp->rm_xid), rep->rr_len); 299 pr_info("RPC: %s: %*ph\n", __func__, rep->rr_len, headerp); 300 #endif 301 302 /* Sanity check: 303 * Need at least enough bytes for RPC/RDMA header, as code 304 * here references the header fields by array offset. Also, 305 * backward calls are always inline, so ensure there 306 * are some bytes beyond the RPC/RDMA header. 307 */ 308 if (rep->rr_len < RPCRDMA_HDRLEN_MIN + 24) 309 goto out_short; 310 p = (__be32 *)((unsigned char *)headerp + RPCRDMA_HDRLEN_MIN); 311 size = rep->rr_len - RPCRDMA_HDRLEN_MIN; 312 313 /* Grab a free bc rqst */ 314 spin_lock(&xprt->bc_pa_lock); 315 if (list_empty(&xprt->bc_pa_list)) { 316 spin_unlock(&xprt->bc_pa_lock); 317 goto out_overflow; 318 } 319 rqst = list_first_entry(&xprt->bc_pa_list, 320 struct rpc_rqst, rq_bc_pa_list); 321 list_del(&rqst->rq_bc_pa_list); 322 spin_unlock(&xprt->bc_pa_lock); 323 dprintk("RPC: %s: using rqst %p\n", __func__, rqst); 324 325 /* Prepare rqst */ 326 rqst->rq_reply_bytes_recvd = 0; 327 rqst->rq_bytes_sent = 0; 328 rqst->rq_xid = headerp->rm_xid; 329 330 rqst->rq_private_buf.len = size; 331 set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); 332 333 buf = &rqst->rq_rcv_buf; 334 memset(buf, 0, sizeof(*buf)); 335 buf->head[0].iov_base = p; 336 buf->head[0].iov_len = size; 337 buf->len = size; 338 339 /* The receive buffer has to be hooked to the rpcrdma_req 340 * so that it can be reposted after the server is done 341 * parsing it but just before sending the backward 342 * direction reply. 343 */ 344 req = rpcr_to_rdmar(rqst); 345 dprintk("RPC: %s: attaching rep %p to req %p\n", 346 __func__, rep, req); 347 req->rl_reply = rep; 348 349 /* Defeat the retransmit detection logic in send_request */ 350 req->rl_connect_cookie = 0; 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 out_short: 372 pr_warn("RPC/RDMA short backward direction call\n"); 373 374 if (rpcrdma_ep_post_recv(&r_xprt->rx_ia, rep)) 375 xprt_disconnect_done(xprt); 376 else 377 pr_warn("RPC: %s: reposting rep %p\n", 378 __func__, rep); 379 } 380