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f531a5db CL |
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> | |
63cae470 CL |
8 | #include <linux/sunrpc/xprt.h> |
9 | #include <linux/sunrpc/svc.h> | |
76566773 | 10 | #include <linux/sunrpc/svc_xprt.h> |
f531a5db CL |
11 | |
12 | #include "xprt_rdma.h" | |
13 | ||
14 | #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) | |
15 | # define RPCDBG_FACILITY RPCDBG_TRANS | |
16 | #endif | |
17 | ||
c8bbe0c7 | 18 | #undef RPCRDMA_BACKCHANNEL_DEBUG |
63cae470 | 19 | |
f531a5db CL |
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 | ||
13650c23 | 30 | rpcrdma_destroy_req(req); |
f531a5db CL |
31 | |
32 | kfree(rqst); | |
33 | } | |
34 | ||
35 | static int rpcrdma_bc_setup_rqst(struct rpcrdma_xprt *r_xprt, | |
36 | struct rpc_rqst *rqst) | |
37 | { | |
f531a5db CL |
38 | struct rpcrdma_regbuf *rb; |
39 | struct rpcrdma_req *req; | |
f531a5db CL |
40 | size_t size; |
41 | ||
42 | req = rpcrdma_create_req(r_xprt); | |
abfb6897 DC |
43 | if (IS_ERR(req)) |
44 | return PTR_ERR(req); | |
f531a5db CL |
45 | req->rl_backchannel = true; |
46 | ||
13650c23 | 47 | rb = rpcrdma_alloc_regbuf(RPCRDMA_HDRBUF_SIZE, |
99ef4db3 | 48 | DMA_TO_DEVICE, GFP_KERNEL); |
f531a5db CL |
49 | if (IS_ERR(rb)) |
50 | goto out_fail; | |
51 | req->rl_rdmabuf = rb; | |
52 | ||
08cf2efd | 53 | size = r_xprt->rx_data.inline_rsize; |
13650c23 | 54 | rb = rpcrdma_alloc_regbuf(size, DMA_TO_DEVICE, GFP_KERNEL); |
f531a5db CL |
55 | if (IS_ERR(rb)) |
56 | goto out_fail; | |
f531a5db | 57 | req->rl_sendbuf = rb; |
62aee0e3 CL |
58 | xdr_buf_init(&rqst->rq_snd_buf, rb->rg_base, |
59 | min_t(size_t, size, PAGE_SIZE)); | |
5a6d1db4 | 60 | rpcrdma_set_xprtdata(rqst, req); |
f531a5db CL |
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 | { | |
f531a5db | 75 | struct rpcrdma_rep *rep; |
f531a5db CL |
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 | ||
9b06688b | 87 | rpcrdma_recv_buffer_put(rep); |
f531a5db CL |
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 | */ | |
124fa17d CL |
117 | if (reqs > RPCRDMA_BACKWARD_WRS >> 1) |
118 | goto out_err; | |
119 | ||
f531a5db CL |
120 | for (i = 0; i < (reqs << 1); i++) { |
121 | rqst = kzalloc(sizeof(*rqst), GFP_KERNEL); | |
122 | if (!rqst) { | |
123 | pr_err("RPC: %s: Failed to create bc rpc_rqst\n", | |
124 | __func__); | |
125 | goto out_free; | |
126 | } | |
c8bbe0c7 | 127 | dprintk("RPC: %s: new rqst %p\n", __func__, rqst); |
f531a5db CL |
128 | |
129 | rqst->rq_xprt = &r_xprt->rx_xprt; | |
130 | INIT_LIST_HEAD(&rqst->rq_list); | |
131 | INIT_LIST_HEAD(&rqst->rq_bc_list); | |
132 | ||
133 | if (rpcrdma_bc_setup_rqst(r_xprt, rqst)) | |
134 | goto out_free; | |
135 | ||
136 | spin_lock_bh(&xprt->bc_pa_lock); | |
137 | list_add(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); | |
138 | spin_unlock_bh(&xprt->bc_pa_lock); | |
139 | } | |
140 | ||
141 | rc = rpcrdma_bc_setup_reps(r_xprt, reqs); | |
142 | if (rc) | |
143 | goto out_free; | |
144 | ||
145 | rc = rpcrdma_ep_post_extra_recv(r_xprt, reqs); | |
146 | if (rc) | |
147 | goto out_free; | |
148 | ||
149 | buffer->rb_bc_srv_max_requests = reqs; | |
150 | request_module("svcrdma"); | |
151 | ||
152 | return 0; | |
153 | ||
154 | out_free: | |
155 | xprt_rdma_bc_destroy(xprt, reqs); | |
156 | ||
124fa17d | 157 | out_err: |
f531a5db CL |
158 | pr_err("RPC: %s: setup backchannel transport failed\n", __func__); |
159 | return -ENOMEM; | |
160 | } | |
161 | ||
76566773 CL |
162 | /** |
163 | * xprt_rdma_bc_up - Create transport endpoint for backchannel service | |
164 | * @serv: server endpoint | |
165 | * @net: network namespace | |
166 | * | |
167 | * The "xprt" is an implied argument: it supplies the name of the | |
168 | * backchannel transport class. | |
169 | * | |
170 | * Returns zero on success, negative errno on failure | |
171 | */ | |
172 | int xprt_rdma_bc_up(struct svc_serv *serv, struct net *net) | |
173 | { | |
174 | int ret; | |
175 | ||
176 | ret = svc_create_xprt(serv, "rdma-bc", net, PF_INET, 0, 0); | |
177 | if (ret < 0) | |
178 | return ret; | |
179 | return 0; | |
180 | } | |
181 | ||
6b26cc8c CL |
182 | /** |
183 | * xprt_rdma_bc_maxpayload - Return maximum backchannel message size | |
184 | * @xprt: transport | |
185 | * | |
186 | * Returns maximum size, in bytes, of a backchannel message | |
187 | */ | |
188 | size_t xprt_rdma_bc_maxpayload(struct rpc_xprt *xprt) | |
189 | { | |
190 | struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); | |
191 | struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data; | |
192 | size_t maxmsg; | |
193 | ||
194 | maxmsg = min_t(unsigned int, cdata->inline_rsize, cdata->inline_wsize); | |
62aee0e3 | 195 | maxmsg = min_t(unsigned int, maxmsg, PAGE_SIZE); |
6b26cc8c CL |
196 | return maxmsg - RPCRDMA_HDRLEN_MIN; |
197 | } | |
198 | ||
83128a60 CL |
199 | /** |
200 | * rpcrdma_bc_marshal_reply - Send backwards direction reply | |
201 | * @rqst: buffer containing RPC reply data | |
202 | * | |
203 | * Returns zero on success. | |
204 | */ | |
205 | int rpcrdma_bc_marshal_reply(struct rpc_rqst *rqst) | |
206 | { | |
207 | struct rpc_xprt *xprt = rqst->rq_xprt; | |
208 | struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); | |
209 | struct rpcrdma_req *req = rpcr_to_rdmar(rqst); | |
210 | struct rpcrdma_msg *headerp; | |
83128a60 CL |
211 | |
212 | headerp = rdmab_to_msg(req->rl_rdmabuf); | |
213 | headerp->rm_xid = rqst->rq_xid; | |
214 | headerp->rm_vers = rpcrdma_version; | |
215 | headerp->rm_credit = | |
216 | cpu_to_be32(r_xprt->rx_buf.rb_bc_srv_max_requests); | |
217 | headerp->rm_type = rdma_msg; | |
218 | headerp->rm_body.rm_chunks[0] = xdr_zero; | |
219 | headerp->rm_body.rm_chunks[1] = xdr_zero; | |
220 | headerp->rm_body.rm_chunks[2] = xdr_zero; | |
221 | ||
655fec69 CL |
222 | if (!rpcrdma_prepare_send_sges(&r_xprt->rx_ia, req, RPCRDMA_HDRLEN_MIN, |
223 | &rqst->rq_snd_buf, rpcrdma_noch)) | |
224 | return -EIO; | |
83128a60 CL |
225 | return 0; |
226 | } | |
227 | ||
f531a5db CL |
228 | /** |
229 | * xprt_rdma_bc_destroy - Release resources for handling backchannel requests | |
230 | * @xprt: transport associated with these backchannel resources | |
231 | * @reqs: number of incoming requests to destroy; ignored | |
232 | */ | |
233 | void xprt_rdma_bc_destroy(struct rpc_xprt *xprt, unsigned int reqs) | |
234 | { | |
235 | struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); | |
236 | struct rpc_rqst *rqst, *tmp; | |
237 | ||
238 | spin_lock_bh(&xprt->bc_pa_lock); | |
239 | list_for_each_entry_safe(rqst, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { | |
240 | list_del(&rqst->rq_bc_pa_list); | |
241 | spin_unlock_bh(&xprt->bc_pa_lock); | |
242 | ||
243 | rpcrdma_bc_free_rqst(r_xprt, rqst); | |
244 | ||
245 | spin_lock_bh(&xprt->bc_pa_lock); | |
246 | } | |
247 | spin_unlock_bh(&xprt->bc_pa_lock); | |
248 | } | |
249 | ||
250 | /** | |
251 | * xprt_rdma_bc_free_rqst - Release a backchannel rqst | |
252 | * @rqst: request to release | |
253 | */ | |
254 | void xprt_rdma_bc_free_rqst(struct rpc_rqst *rqst) | |
255 | { | |
256 | struct rpc_xprt *xprt = rqst->rq_xprt; | |
257 | ||
c8bbe0c7 CL |
258 | dprintk("RPC: %s: freeing rqst %p (req %p)\n", |
259 | __func__, rqst, rpcr_to_rdmar(rqst)); | |
260 | ||
f531a5db CL |
261 | smp_mb__before_atomic(); |
262 | WARN_ON_ONCE(!test_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state)); | |
263 | clear_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); | |
264 | smp_mb__after_atomic(); | |
265 | ||
266 | spin_lock_bh(&xprt->bc_pa_lock); | |
267 | list_add_tail(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); | |
268 | spin_unlock_bh(&xprt->bc_pa_lock); | |
269 | } | |
63cae470 CL |
270 | |
271 | /** | |
272 | * rpcrdma_bc_receive_call - Handle a backward direction call | |
273 | * @xprt: transport receiving the call | |
274 | * @rep: receive buffer containing the call | |
275 | * | |
276 | * Called in the RPC reply handler, which runs in a tasklet. | |
277 | * Be quick about it. | |
278 | * | |
279 | * Operational assumptions: | |
280 | * o Backchannel credits are ignored, just as the NFS server | |
281 | * forechannel currently does | |
282 | * o The ULP manages a replay cache (eg, NFSv4.1 sessions). | |
283 | * No replay detection is done at the transport level | |
284 | */ | |
285 | void rpcrdma_bc_receive_call(struct rpcrdma_xprt *r_xprt, | |
286 | struct rpcrdma_rep *rep) | |
287 | { | |
288 | struct rpc_xprt *xprt = &r_xprt->rx_xprt; | |
289 | struct rpcrdma_msg *headerp; | |
290 | struct svc_serv *bc_serv; | |
291 | struct rpcrdma_req *req; | |
292 | struct rpc_rqst *rqst; | |
293 | struct xdr_buf *buf; | |
294 | size_t size; | |
295 | __be32 *p; | |
296 | ||
297 | headerp = rdmab_to_msg(rep->rr_rdmabuf); | |
298 | #ifdef RPCRDMA_BACKCHANNEL_DEBUG | |
299 | pr_info("RPC: %s: callback XID %08x, length=%u\n", | |
300 | __func__, be32_to_cpu(headerp->rm_xid), rep->rr_len); | |
301 | pr_info("RPC: %s: %*ph\n", __func__, rep->rr_len, headerp); | |
302 | #endif | |
303 | ||
304 | /* Sanity check: | |
305 | * Need at least enough bytes for RPC/RDMA header, as code | |
306 | * here references the header fields by array offset. Also, | |
307 | * backward calls are always inline, so ensure there | |
308 | * are some bytes beyond the RPC/RDMA header. | |
309 | */ | |
310 | if (rep->rr_len < RPCRDMA_HDRLEN_MIN + 24) | |
311 | goto out_short; | |
312 | p = (__be32 *)((unsigned char *)headerp + RPCRDMA_HDRLEN_MIN); | |
313 | size = rep->rr_len - RPCRDMA_HDRLEN_MIN; | |
314 | ||
315 | /* Grab a free bc rqst */ | |
316 | spin_lock(&xprt->bc_pa_lock); | |
317 | if (list_empty(&xprt->bc_pa_list)) { | |
318 | spin_unlock(&xprt->bc_pa_lock); | |
319 | goto out_overflow; | |
320 | } | |
321 | rqst = list_first_entry(&xprt->bc_pa_list, | |
322 | struct rpc_rqst, rq_bc_pa_list); | |
323 | list_del(&rqst->rq_bc_pa_list); | |
324 | spin_unlock(&xprt->bc_pa_lock); | |
c8bbe0c7 | 325 | dprintk("RPC: %s: using rqst %p\n", __func__, rqst); |
63cae470 CL |
326 | |
327 | /* Prepare rqst */ | |
328 | rqst->rq_reply_bytes_recvd = 0; | |
329 | rqst->rq_bytes_sent = 0; | |
330 | rqst->rq_xid = headerp->rm_xid; | |
9f74660b CL |
331 | |
332 | rqst->rq_private_buf.len = size; | |
63cae470 CL |
333 | set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); |
334 | ||
335 | buf = &rqst->rq_rcv_buf; | |
336 | memset(buf, 0, sizeof(*buf)); | |
337 | buf->head[0].iov_base = p; | |
338 | buf->head[0].iov_len = size; | |
339 | buf->len = size; | |
340 | ||
341 | /* The receive buffer has to be hooked to the rpcrdma_req | |
342 | * so that it can be reposted after the server is done | |
343 | * parsing it but just before sending the backward | |
344 | * direction reply. | |
345 | */ | |
346 | req = rpcr_to_rdmar(rqst); | |
c8bbe0c7 | 347 | dprintk("RPC: %s: attaching rep %p to req %p\n", |
63cae470 | 348 | __func__, rep, req); |
63cae470 CL |
349 | req->rl_reply = rep; |
350 | ||
351 | /* Defeat the retransmit detection logic in send_request */ | |
352 | req->rl_connect_cookie = 0; | |
353 | ||
354 | /* Queue rqst for ULP's callback service */ | |
355 | bc_serv = xprt->bc_serv; | |
356 | spin_lock(&bc_serv->sv_cb_lock); | |
357 | list_add(&rqst->rq_bc_list, &bc_serv->sv_cb_list); | |
358 | spin_unlock(&bc_serv->sv_cb_lock); | |
359 | ||
360 | wake_up(&bc_serv->sv_cb_waitq); | |
361 | ||
362 | r_xprt->rx_stats.bcall_count++; | |
363 | return; | |
364 | ||
365 | out_overflow: | |
366 | pr_warn("RPC/RDMA backchannel overflow\n"); | |
367 | xprt_disconnect_done(xprt); | |
368 | /* This receive buffer gets reposted automatically | |
369 | * when the connection is re-established. | |
370 | */ | |
371 | return; | |
372 | ||
373 | out_short: | |
374 | pr_warn("RPC/RDMA short backward direction call\n"); | |
375 | ||
b157380a | 376 | if (rpcrdma_ep_post_recv(&r_xprt->rx_ia, rep)) |
63cae470 CL |
377 | xprt_disconnect_done(xprt); |
378 | else | |
379 | pr_warn("RPC: %s: reposting rep %p\n", | |
380 | __func__, rep); | |
381 | } |