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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; | |
7ec910e7 | 52 | xdr_buf_init(&req->rl_hdrbuf, rb->rg_base, rdmab_length(rb)); |
f531a5db | 53 | |
08cf2efd | 54 | size = r_xprt->rx_data.inline_rsize; |
13650c23 | 55 | rb = rpcrdma_alloc_regbuf(size, DMA_TO_DEVICE, GFP_KERNEL); |
f531a5db CL |
56 | if (IS_ERR(rb)) |
57 | goto out_fail; | |
f531a5db | 58 | req->rl_sendbuf = rb; |
62aee0e3 CL |
59 | xdr_buf_init(&rqst->rq_snd_buf, rb->rg_base, |
60 | min_t(size_t, size, PAGE_SIZE)); | |
5a6d1db4 | 61 | rpcrdma_set_xprtdata(rqst, req); |
f531a5db CL |
62 | return 0; |
63 | ||
64 | out_fail: | |
65 | rpcrdma_bc_free_rqst(r_xprt, rqst); | |
66 | return -ENOMEM; | |
67 | } | |
68 | ||
69 | /* Allocate and add receive buffers to the rpcrdma_buffer's | |
70 | * existing list of rep's. These are released when the | |
71 | * transport is destroyed. | |
72 | */ | |
73 | static int rpcrdma_bc_setup_reps(struct rpcrdma_xprt *r_xprt, | |
74 | unsigned int count) | |
75 | { | |
f531a5db | 76 | struct rpcrdma_rep *rep; |
f531a5db CL |
77 | int rc = 0; |
78 | ||
79 | while (count--) { | |
80 | rep = rpcrdma_create_rep(r_xprt); | |
81 | if (IS_ERR(rep)) { | |
82 | pr_err("RPC: %s: reply buffer alloc failed\n", | |
83 | __func__); | |
84 | rc = PTR_ERR(rep); | |
85 | break; | |
86 | } | |
87 | ||
9b06688b | 88 | rpcrdma_recv_buffer_put(rep); |
f531a5db CL |
89 | } |
90 | ||
91 | return rc; | |
92 | } | |
93 | ||
94 | /** | |
95 | * xprt_rdma_bc_setup - Pre-allocate resources for handling backchannel requests | |
96 | * @xprt: transport associated with these backchannel resources | |
97 | * @reqs: number of concurrent incoming requests to expect | |
98 | * | |
99 | * Returns 0 on success; otherwise a negative errno | |
100 | */ | |
101 | int xprt_rdma_bc_setup(struct rpc_xprt *xprt, unsigned int reqs) | |
102 | { | |
103 | struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); | |
104 | struct rpcrdma_buffer *buffer = &r_xprt->rx_buf; | |
105 | struct rpc_rqst *rqst; | |
106 | unsigned int i; | |
107 | int rc; | |
108 | ||
109 | /* The backchannel reply path returns each rpc_rqst to the | |
110 | * bc_pa_list _after_ the reply is sent. If the server is | |
111 | * faster than the client, it can send another backward | |
112 | * direction request before the rpc_rqst is returned to the | |
113 | * list. The client rejects the request in this case. | |
114 | * | |
115 | * Twice as many rpc_rqsts are prepared to ensure there is | |
116 | * always an rpc_rqst available as soon as a reply is sent. | |
117 | */ | |
124fa17d CL |
118 | if (reqs > RPCRDMA_BACKWARD_WRS >> 1) |
119 | goto out_err; | |
120 | ||
f531a5db CL |
121 | for (i = 0; i < (reqs << 1); i++) { |
122 | rqst = kzalloc(sizeof(*rqst), GFP_KERNEL); | |
d2c23c00 | 123 | if (!rqst) |
f531a5db | 124 | goto out_free; |
d2c23c00 | 125 | |
c8bbe0c7 | 126 | dprintk("RPC: %s: new rqst %p\n", __func__, rqst); |
f531a5db CL |
127 | |
128 | rqst->rq_xprt = &r_xprt->rx_xprt; | |
129 | INIT_LIST_HEAD(&rqst->rq_list); | |
130 | INIT_LIST_HEAD(&rqst->rq_bc_list); | |
131 | ||
132 | if (rpcrdma_bc_setup_rqst(r_xprt, rqst)) | |
133 | goto out_free; | |
134 | ||
135 | spin_lock_bh(&xprt->bc_pa_lock); | |
136 | list_add(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); | |
137 | spin_unlock_bh(&xprt->bc_pa_lock); | |
138 | } | |
139 | ||
140 | rc = rpcrdma_bc_setup_reps(r_xprt, reqs); | |
141 | if (rc) | |
142 | goto out_free; | |
143 | ||
144 | rc = rpcrdma_ep_post_extra_recv(r_xprt, reqs); | |
145 | if (rc) | |
146 | goto out_free; | |
147 | ||
148 | buffer->rb_bc_srv_max_requests = reqs; | |
149 | request_module("svcrdma"); | |
150 | ||
151 | return 0; | |
152 | ||
153 | out_free: | |
154 | xprt_rdma_bc_destroy(xprt, reqs); | |
155 | ||
124fa17d | 156 | out_err: |
f531a5db CL |
157 | pr_err("RPC: %s: setup backchannel transport failed\n", __func__); |
158 | return -ENOMEM; | |
159 | } | |
160 | ||
76566773 CL |
161 | /** |
162 | * xprt_rdma_bc_up - Create transport endpoint for backchannel service | |
163 | * @serv: server endpoint | |
164 | * @net: network namespace | |
165 | * | |
166 | * The "xprt" is an implied argument: it supplies the name of the | |
167 | * backchannel transport class. | |
168 | * | |
169 | * Returns zero on success, negative errno on failure | |
170 | */ | |
171 | int xprt_rdma_bc_up(struct svc_serv *serv, struct net *net) | |
172 | { | |
173 | int ret; | |
174 | ||
175 | ret = svc_create_xprt(serv, "rdma-bc", net, PF_INET, 0, 0); | |
176 | if (ret < 0) | |
177 | return ret; | |
178 | return 0; | |
179 | } | |
180 | ||
6b26cc8c CL |
181 | /** |
182 | * xprt_rdma_bc_maxpayload - Return maximum backchannel message size | |
183 | * @xprt: transport | |
184 | * | |
185 | * Returns maximum size, in bytes, of a backchannel message | |
186 | */ | |
187 | size_t xprt_rdma_bc_maxpayload(struct rpc_xprt *xprt) | |
188 | { | |
189 | struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); | |
190 | struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data; | |
191 | size_t maxmsg; | |
192 | ||
193 | maxmsg = min_t(unsigned int, cdata->inline_rsize, cdata->inline_wsize); | |
62aee0e3 | 194 | maxmsg = min_t(unsigned int, maxmsg, PAGE_SIZE); |
6b26cc8c CL |
195 | return maxmsg - RPCRDMA_HDRLEN_MIN; |
196 | } | |
197 | ||
83128a60 CL |
198 | /** |
199 | * rpcrdma_bc_marshal_reply - Send backwards direction reply | |
200 | * @rqst: buffer containing RPC reply data | |
201 | * | |
202 | * Returns zero on success. | |
203 | */ | |
204 | int rpcrdma_bc_marshal_reply(struct rpc_rqst *rqst) | |
205 | { | |
7ec910e7 | 206 | struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_xprt); |
83128a60 | 207 | struct rpcrdma_req *req = rpcr_to_rdmar(rqst); |
7ec910e7 CL |
208 | __be32 *p; |
209 | ||
210 | rpcrdma_set_xdrlen(&req->rl_hdrbuf, 0); | |
211 | xdr_init_encode(&req->rl_stream, &req->rl_hdrbuf, | |
212 | req->rl_rdmabuf->rg_base); | |
213 | ||
214 | p = xdr_reserve_space(&req->rl_stream, 28); | |
215 | if (unlikely(!p)) | |
216 | return -EIO; | |
217 | *p++ = rqst->rq_xid; | |
218 | *p++ = rpcrdma_version; | |
219 | *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_srv_max_requests); | |
220 | *p++ = rdma_msg; | |
221 | *p++ = xdr_zero; | |
222 | *p++ = xdr_zero; | |
223 | *p = xdr_zero; | |
83128a60 | 224 | |
655fec69 CL |
225 | if (!rpcrdma_prepare_send_sges(&r_xprt->rx_ia, req, RPCRDMA_HDRLEN_MIN, |
226 | &rqst->rq_snd_buf, rpcrdma_noch)) | |
227 | return -EIO; | |
83128a60 CL |
228 | return 0; |
229 | } | |
230 | ||
f531a5db CL |
231 | /** |
232 | * xprt_rdma_bc_destroy - Release resources for handling backchannel requests | |
233 | * @xprt: transport associated with these backchannel resources | |
234 | * @reqs: number of incoming requests to destroy; ignored | |
235 | */ | |
236 | void xprt_rdma_bc_destroy(struct rpc_xprt *xprt, unsigned int reqs) | |
237 | { | |
238 | struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); | |
239 | struct rpc_rqst *rqst, *tmp; | |
240 | ||
241 | spin_lock_bh(&xprt->bc_pa_lock); | |
242 | list_for_each_entry_safe(rqst, tmp, &xprt->bc_pa_list, rq_bc_pa_list) { | |
243 | list_del(&rqst->rq_bc_pa_list); | |
244 | spin_unlock_bh(&xprt->bc_pa_lock); | |
245 | ||
246 | rpcrdma_bc_free_rqst(r_xprt, rqst); | |
247 | ||
248 | spin_lock_bh(&xprt->bc_pa_lock); | |
249 | } | |
250 | spin_unlock_bh(&xprt->bc_pa_lock); | |
251 | } | |
252 | ||
253 | /** | |
254 | * xprt_rdma_bc_free_rqst - Release a backchannel rqst | |
255 | * @rqst: request to release | |
256 | */ | |
257 | void xprt_rdma_bc_free_rqst(struct rpc_rqst *rqst) | |
258 | { | |
259 | struct rpc_xprt *xprt = rqst->rq_xprt; | |
260 | ||
c8bbe0c7 CL |
261 | dprintk("RPC: %s: freeing rqst %p (req %p)\n", |
262 | __func__, rqst, rpcr_to_rdmar(rqst)); | |
263 | ||
f531a5db CL |
264 | smp_mb__before_atomic(); |
265 | WARN_ON_ONCE(!test_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state)); | |
266 | clear_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); | |
267 | smp_mb__after_atomic(); | |
268 | ||
269 | spin_lock_bh(&xprt->bc_pa_lock); | |
270 | list_add_tail(&rqst->rq_bc_pa_list, &xprt->bc_pa_list); | |
271 | spin_unlock_bh(&xprt->bc_pa_lock); | |
272 | } | |
63cae470 CL |
273 | |
274 | /** | |
275 | * rpcrdma_bc_receive_call - Handle a backward direction call | |
276 | * @xprt: transport receiving the call | |
277 | * @rep: receive buffer containing the call | |
278 | * | |
63cae470 CL |
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; | |
63cae470 CL |
289 | struct svc_serv *bc_serv; |
290 | struct rpcrdma_req *req; | |
291 | struct rpc_rqst *rqst; | |
292 | struct xdr_buf *buf; | |
293 | size_t size; | |
294 | __be32 *p; | |
295 | ||
41c8f70f CL |
296 | p = xdr_inline_decode(&rep->rr_stream, 0); |
297 | size = xdr_stream_remaining(&rep->rr_stream); | |
298 | ||
63cae470 CL |
299 | #ifdef RPCRDMA_BACKCHANNEL_DEBUG |
300 | pr_info("RPC: %s: callback XID %08x, length=%u\n", | |
41c8f70f CL |
301 | __func__, be32_to_cpup(p), size); |
302 | pr_info("RPC: %s: %*ph\n", __func__, size, p); | |
63cae470 CL |
303 | #endif |
304 | ||
63cae470 CL |
305 | /* Grab a free bc rqst */ |
306 | spin_lock(&xprt->bc_pa_lock); | |
307 | if (list_empty(&xprt->bc_pa_list)) { | |
308 | spin_unlock(&xprt->bc_pa_lock); | |
309 | goto out_overflow; | |
310 | } | |
311 | rqst = list_first_entry(&xprt->bc_pa_list, | |
312 | struct rpc_rqst, rq_bc_pa_list); | |
313 | list_del(&rqst->rq_bc_pa_list); | |
314 | spin_unlock(&xprt->bc_pa_lock); | |
c8bbe0c7 | 315 | dprintk("RPC: %s: using rqst %p\n", __func__, rqst); |
63cae470 CL |
316 | |
317 | /* Prepare rqst */ | |
318 | rqst->rq_reply_bytes_recvd = 0; | |
319 | rqst->rq_bytes_sent = 0; | |
41c8f70f | 320 | rqst->rq_xid = *p; |
9f74660b CL |
321 | |
322 | rqst->rq_private_buf.len = size; | |
63cae470 CL |
323 | set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state); |
324 | ||
325 | buf = &rqst->rq_rcv_buf; | |
326 | memset(buf, 0, sizeof(*buf)); | |
327 | buf->head[0].iov_base = p; | |
328 | buf->head[0].iov_len = size; | |
329 | buf->len = size; | |
330 | ||
331 | /* The receive buffer has to be hooked to the rpcrdma_req | |
41c8f70f CL |
332 | * so that it is not released while the req is pointing |
333 | * to its buffer, and so that it can be reposted after | |
334 | * the Upper Layer is done decoding it. | |
63cae470 CL |
335 | */ |
336 | req = rpcr_to_rdmar(rqst); | |
c8bbe0c7 | 337 | dprintk("RPC: %s: attaching rep %p to req %p\n", |
63cae470 | 338 | __func__, rep, req); |
63cae470 CL |
339 | req->rl_reply = rep; |
340 | ||
341 | /* Defeat the retransmit detection logic in send_request */ | |
342 | req->rl_connect_cookie = 0; | |
343 | ||
344 | /* Queue rqst for ULP's callback service */ | |
345 | bc_serv = xprt->bc_serv; | |
346 | spin_lock(&bc_serv->sv_cb_lock); | |
347 | list_add(&rqst->rq_bc_list, &bc_serv->sv_cb_list); | |
348 | spin_unlock(&bc_serv->sv_cb_lock); | |
349 | ||
350 | wake_up(&bc_serv->sv_cb_waitq); | |
351 | ||
352 | r_xprt->rx_stats.bcall_count++; | |
353 | return; | |
354 | ||
355 | out_overflow: | |
356 | pr_warn("RPC/RDMA backchannel overflow\n"); | |
357 | xprt_disconnect_done(xprt); | |
358 | /* This receive buffer gets reposted automatically | |
359 | * when the connection is re-established. | |
360 | */ | |
361 | return; | |
63cae470 | 362 | } |