Merge branch 'idr-2018-02-06' of git://git.infradead.org/users/willy/linux-dax
[muen/linux.git] / net / sunrpc / xprtrdma / svc_rdma_backchannel.c
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 (server-side).
6  */
7
8 #include <linux/module.h>
9 #include <linux/sunrpc/svc_rdma.h>
10 #include "xprt_rdma.h"
11
12 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
13
14 #undef SVCRDMA_BACKCHANNEL_DEBUG
15
16 /**
17  * svc_rdma_handle_bc_reply - Process incoming backchannel reply
18  * @xprt: controlling backchannel transport
19  * @rdma_resp: pointer to incoming transport header
20  * @rcvbuf: XDR buffer into which to decode the reply
21  *
22  * Returns:
23  *      %0 if @rcvbuf is filled in, xprt_complete_rqst called,
24  *      %-EAGAIN if server should call ->recvfrom again.
25  */
26 int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, __be32 *rdma_resp,
27                              struct xdr_buf *rcvbuf)
28 {
29         struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
30         struct kvec *dst, *src = &rcvbuf->head[0];
31         struct rpc_rqst *req;
32         unsigned long cwnd;
33         u32 credits;
34         size_t len;
35         __be32 xid;
36         __be32 *p;
37         int ret;
38
39         p = (__be32 *)src->iov_base;
40         len = src->iov_len;
41         xid = *rdma_resp;
42
43 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
44         pr_info("%s: xid=%08x, length=%zu\n",
45                 __func__, be32_to_cpu(xid), len);
46         pr_info("%s: RPC/RDMA: %*ph\n",
47                 __func__, (int)RPCRDMA_HDRLEN_MIN, rdma_resp);
48         pr_info("%s:      RPC: %*ph\n",
49                 __func__, (int)len, p);
50 #endif
51
52         ret = -EAGAIN;
53         if (src->iov_len < 24)
54                 goto out_shortreply;
55
56         spin_lock(&xprt->recv_lock);
57         req = xprt_lookup_rqst(xprt, xid);
58         if (!req)
59                 goto out_notfound;
60
61         dst = &req->rq_private_buf.head[0];
62         memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
63         if (dst->iov_len < len)
64                 goto out_unlock;
65         memcpy(dst->iov_base, p, len);
66
67         credits = be32_to_cpup(rdma_resp + 2);
68         if (credits == 0)
69                 credits = 1;    /* don't deadlock */
70         else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
71                 credits = r_xprt->rx_buf.rb_bc_max_requests;
72
73         spin_lock_bh(&xprt->transport_lock);
74         cwnd = xprt->cwnd;
75         xprt->cwnd = credits << RPC_CWNDSHIFT;
76         if (xprt->cwnd > cwnd)
77                 xprt_release_rqst_cong(req->rq_task);
78         spin_unlock_bh(&xprt->transport_lock);
79
80
81         ret = 0;
82         xprt_complete_rqst(req->rq_task, rcvbuf->len);
83         rcvbuf->len = 0;
84
85 out_unlock:
86         spin_unlock(&xprt->recv_lock);
87 out:
88         return ret;
89
90 out_shortreply:
91         dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n",
92                 xprt, src->iov_len);
93         goto out;
94
95 out_notfound:
96         dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n",
97                 xprt, be32_to_cpu(xid));
98
99         goto out_unlock;
100 }
101
102 /* Send a backwards direction RPC call.
103  *
104  * Caller holds the connection's mutex and has already marshaled
105  * the RPC/RDMA request.
106  *
107  * This is similar to svc_rdma_send_reply_msg, but takes a struct
108  * rpc_rqst instead, does not support chunks, and avoids blocking
109  * memory allocation.
110  *
111  * XXX: There is still an opportunity to block in svc_rdma_send()
112  * if there are no SQ entries to post the Send. This may occur if
113  * the adapter has a small maximum SQ depth.
114  */
115 static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
116                               struct rpc_rqst *rqst)
117 {
118         struct svc_rdma_op_ctxt *ctxt;
119         int ret;
120
121         ctxt = svc_rdma_get_context(rdma);
122
123         /* rpcrdma_bc_send_request builds the transport header and
124          * the backchannel RPC message in the same buffer. Thus only
125          * one SGE is needed to send both.
126          */
127         ret = svc_rdma_map_reply_hdr(rdma, ctxt, rqst->rq_buffer,
128                                      rqst->rq_snd_buf.len);
129         if (ret < 0)
130                 goto out_err;
131
132         ret = svc_rdma_repost_recv(rdma, GFP_NOIO);
133         if (ret)
134                 goto out_err;
135
136         /* Bump page refcnt so Send completion doesn't release
137          * the rq_buffer before all retransmits are complete.
138          */
139         get_page(virt_to_page(rqst->rq_buffer));
140         ret = svc_rdma_post_send_wr(rdma, ctxt, 1, 0);
141         if (ret)
142                 goto out_unmap;
143
144 out_err:
145         dprintk("svcrdma: %s returns %d\n", __func__, ret);
146         return ret;
147
148 out_unmap:
149         svc_rdma_unmap_dma(ctxt);
150         svc_rdma_put_context(ctxt, 1);
151         ret = -EIO;
152         goto out_err;
153 }
154
155 /* Server-side transport endpoint wants a whole page for its send
156  * buffer. The client RPC code constructs the RPC header in this
157  * buffer before it invokes ->send_request.
158  */
159 static int
160 xprt_rdma_bc_allocate(struct rpc_task *task)
161 {
162         struct rpc_rqst *rqst = task->tk_rqstp;
163         size_t size = rqst->rq_callsize;
164         struct page *page;
165
166         if (size > PAGE_SIZE) {
167                 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
168                           size);
169                 return -EINVAL;
170         }
171
172         page = alloc_page(RPCRDMA_DEF_GFP);
173         if (!page)
174                 return -ENOMEM;
175         rqst->rq_buffer = page_address(page);
176
177         rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
178         if (!rqst->rq_rbuffer) {
179                 put_page(page);
180                 return -ENOMEM;
181         }
182         return 0;
183 }
184
185 static void
186 xprt_rdma_bc_free(struct rpc_task *task)
187 {
188         struct rpc_rqst *rqst = task->tk_rqstp;
189
190         put_page(virt_to_page(rqst->rq_buffer));
191         kfree(rqst->rq_rbuffer);
192 }
193
194 static int
195 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
196 {
197         struct rpc_xprt *xprt = rqst->rq_xprt;
198         struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
199         __be32 *p;
200         int rc;
201
202         /* Space in the send buffer for an RPC/RDMA header is reserved
203          * via xprt->tsh_size.
204          */
205         p = rqst->rq_buffer;
206         *p++ = rqst->rq_xid;
207         *p++ = rpcrdma_version;
208         *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
209         *p++ = rdma_msg;
210         *p++ = xdr_zero;
211         *p++ = xdr_zero;
212         *p   = xdr_zero;
213
214 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
215         pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer);
216 #endif
217
218         rc = svc_rdma_bc_sendto(rdma, rqst);
219         if (rc)
220                 goto drop_connection;
221         return rc;
222
223 drop_connection:
224         dprintk("svcrdma: failed to send bc call\n");
225         xprt_disconnect_done(xprt);
226         return -ENOTCONN;
227 }
228
229 /* Send an RPC call on the passive end of a transport
230  * connection.
231  */
232 static int
233 xprt_rdma_bc_send_request(struct rpc_task *task)
234 {
235         struct rpc_rqst *rqst = task->tk_rqstp;
236         struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
237         struct svcxprt_rdma *rdma;
238         int ret;
239
240         dprintk("svcrdma: sending bc call with xid: %08x\n",
241                 be32_to_cpu(rqst->rq_xid));
242
243         if (!mutex_trylock(&sxprt->xpt_mutex)) {
244                 rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL);
245                 if (!mutex_trylock(&sxprt->xpt_mutex))
246                         return -EAGAIN;
247                 rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task);
248         }
249
250         ret = -ENOTCONN;
251         rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
252         if (!test_bit(XPT_DEAD, &sxprt->xpt_flags))
253                 ret = rpcrdma_bc_send_request(rdma, rqst);
254
255         mutex_unlock(&sxprt->xpt_mutex);
256
257         if (ret < 0)
258                 return ret;
259         return 0;
260 }
261
262 static void
263 xprt_rdma_bc_close(struct rpc_xprt *xprt)
264 {
265         dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
266 }
267
268 static void
269 xprt_rdma_bc_put(struct rpc_xprt *xprt)
270 {
271         dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
272
273         xprt_free(xprt);
274         module_put(THIS_MODULE);
275 }
276
277 static const struct rpc_xprt_ops xprt_rdma_bc_procs = {
278         .reserve_xprt           = xprt_reserve_xprt_cong,
279         .release_xprt           = xprt_release_xprt_cong,
280         .alloc_slot             = xprt_alloc_slot,
281         .release_request        = xprt_release_rqst_cong,
282         .buf_alloc              = xprt_rdma_bc_allocate,
283         .buf_free               = xprt_rdma_bc_free,
284         .send_request           = xprt_rdma_bc_send_request,
285         .set_retrans_timeout    = xprt_set_retrans_timeout_def,
286         .close                  = xprt_rdma_bc_close,
287         .destroy                = xprt_rdma_bc_put,
288         .print_stats            = xprt_rdma_print_stats
289 };
290
291 static const struct rpc_timeout xprt_rdma_bc_timeout = {
292         .to_initval = 60 * HZ,
293         .to_maxval = 60 * HZ,
294 };
295
296 /* It shouldn't matter if the number of backchannel session slots
297  * doesn't match the number of RPC/RDMA credits. That just means
298  * one or the other will have extra slots that aren't used.
299  */
300 static struct rpc_xprt *
301 xprt_setup_rdma_bc(struct xprt_create *args)
302 {
303         struct rpc_xprt *xprt;
304         struct rpcrdma_xprt *new_xprt;
305
306         if (args->addrlen > sizeof(xprt->addr)) {
307                 dprintk("RPC:       %s: address too large\n", __func__);
308                 return ERR_PTR(-EBADF);
309         }
310
311         xprt = xprt_alloc(args->net, sizeof(*new_xprt),
312                           RPCRDMA_MAX_BC_REQUESTS,
313                           RPCRDMA_MAX_BC_REQUESTS);
314         if (!xprt) {
315                 dprintk("RPC:       %s: couldn't allocate rpc_xprt\n",
316                         __func__);
317                 return ERR_PTR(-ENOMEM);
318         }
319
320         xprt->timeout = &xprt_rdma_bc_timeout;
321         xprt_set_bound(xprt);
322         xprt_set_connected(xprt);
323         xprt->bind_timeout = RPCRDMA_BIND_TO;
324         xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
325         xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO;
326
327         xprt->prot = XPRT_TRANSPORT_BC_RDMA;
328         xprt->tsh_size = RPCRDMA_HDRLEN_MIN / sizeof(__be32);
329         xprt->ops = &xprt_rdma_bc_procs;
330
331         memcpy(&xprt->addr, args->dstaddr, args->addrlen);
332         xprt->addrlen = args->addrlen;
333         xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
334         xprt->resvport = 0;
335
336         xprt->max_payload = xprt_rdma_max_inline_read;
337
338         new_xprt = rpcx_to_rdmax(xprt);
339         new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
340
341         xprt_get(xprt);
342         args->bc_xprt->xpt_bc_xprt = xprt;
343         xprt->bc_xprt = args->bc_xprt;
344
345         if (!try_module_get(THIS_MODULE))
346                 goto out_fail;
347
348         /* Final put for backchannel xprt is in __svc_rdma_free */
349         xprt_get(xprt);
350         return xprt;
351
352 out_fail:
353         xprt_rdma_free_addresses(xprt);
354         args->bc_xprt->xpt_bc_xprt = NULL;
355         args->bc_xprt->xpt_bc_xps = NULL;
356         xprt_put(xprt);
357         xprt_free(xprt);
358         return ERR_PTR(-EINVAL);
359 }
360
361 struct xprt_class xprt_rdma_bc = {
362         .list                   = LIST_HEAD_INIT(xprt_rdma_bc.list),
363         .name                   = "rdma backchannel",
364         .owner                  = THIS_MODULE,
365         .ident                  = XPRT_TRANSPORT_BC_RDMA,
366         .setup                  = xprt_setup_rdma_bc,
367 };