net/sunrpc/xprtrdma/svc_rdma_backchannel.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2015-2018 Oracle.  All rights reserved.
   4  *
   5  * Support for backward direction RPCs on RPC/RDMA (server-side).
   6  */
   7
   8 #include <linux/module.h>
   9
  10 #include <linux/sunrpc/svc_rdma.h>
  11
  12 #include "xprt_rdma.h"
  13 #include <trace/events/rpcrdma.h>
  14
  15 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
  16
  17 #undef SVCRDMA_BACKCHANNEL_DEBUG
  18
  19 /**
  20  * svc_rdma_handle_bc_reply - Process incoming backchannel reply
  21  * @xprt: controlling backchannel transport
  22  * @rdma_resp: pointer to incoming transport header
  23  * @rcvbuf: XDR buffer into which to decode the reply
  24  *
  25  * Returns:
  26  *      %0 if @rcvbuf is filled in, xprt_complete_rqst called,
  27  *      %-EAGAIN if server should call ->recvfrom again.
  28  */
  29 int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, __be32 *rdma_resp,
  30                              struct xdr_buf *rcvbuf)
  31 {
  32         struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
  33         struct kvec *dst, *src = &rcvbuf->head[0];
  34         struct rpc_rqst *req;
  35         unsigned long cwnd;
  36         u32 credits;
  37         size_t len;
  38         __be32 xid;
  39         __be32 *p;
  40         int ret;
  41
  42         p = (__be32 *)src->iov_base;
  43         len = src->iov_len;
  44         xid = *rdma_resp;
  45
  46 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
  47         pr_info("%s: xid=%08x, length=%zu\n",
  48                 __func__, be32_to_cpu(xid), len);
  49         pr_info("%s: RPC/RDMA: %*ph\n",
  50                 __func__, (int)RPCRDMA_HDRLEN_MIN, rdma_resp);
  51         pr_info("%s:      RPC: %*ph\n",
  52                 __func__, (int)len, p);
  53 #endif
  54
  55         ret = -EAGAIN;
  56         if (src->iov_len < 24)
  57                 goto out_shortreply;
  58
  59         spin_lock(&xprt->queue_lock);
  60         req = xprt_lookup_rqst(xprt, xid);
  61         if (!req)
  62                 goto out_notfound;
  63
  64         dst = &req->rq_private_buf.head[0];
  65         memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
  66         if (dst->iov_len < len)
  67                 goto out_unlock;
  68         memcpy(dst->iov_base, p, len);
  69
  70         credits = be32_to_cpup(rdma_resp + 2);
  71         if (credits == 0)
  72                 credits = 1;    /* don't deadlock */
  73         else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
  74                 credits = r_xprt->rx_buf.rb_bc_max_requests;
  75
  76         spin_lock_bh(&xprt->transport_lock);
  77         cwnd = xprt->cwnd;
  78         xprt->cwnd = credits << RPC_CWNDSHIFT;
  79         if (xprt->cwnd > cwnd)
  80                 xprt_release_rqst_cong(req->rq_task);
  81         spin_unlock_bh(&xprt->transport_lock);
  82
  83
  84         ret = 0;
  85         xprt_complete_rqst(req->rq_task, rcvbuf->len);
  86         rcvbuf->len = 0;
  87
  88 out_unlock:
  89         spin_unlock(&xprt->queue_lock);
  90 out:
  91         return ret;
  92
  93 out_shortreply:
  94         dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n",
  95                 xprt, src->iov_len);
  96         goto out;
  97
  98 out_notfound:
  99         dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n",
 100                 xprt, be32_to_cpu(xid));
 101         goto out_unlock;
 102 }
 103
 104 /* Send a backwards direction RPC call.
 105  *
 106  * Caller holds the connection's mutex and has already marshaled
 107  * the RPC/RDMA request.
 108  *
 109  * This is similar to svc_rdma_send_reply_msg, but takes a struct
 110  * rpc_rqst instead, does not support chunks, and avoids blocking
 111  * memory allocation.
 112  *
 113  * XXX: There is still an opportunity to block in svc_rdma_send()
 114  * if there are no SQ entries to post the Send. This may occur if
 115  * the adapter has a small maximum SQ depth.
 116  */
 117 static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
 118                               struct rpc_rqst *rqst,
 119                               struct svc_rdma_send_ctxt *ctxt)
 120 {
 121         int ret;
 122
 123         ret = svc_rdma_map_reply_msg(rdma, ctxt, &rqst->rq_snd_buf, NULL);
 124         if (ret < 0)
 125                 return -EIO;
 126
 127         /* Bump page refcnt so Send completion doesn't release
 128          * the rq_buffer before all retransmits are complete.
 129          */
 130         get_page(virt_to_page(rqst->rq_buffer));
 131         ctxt->sc_send_wr.opcode = IB_WR_SEND;
 132         return svc_rdma_send(rdma, &ctxt->sc_send_wr);
 133 }
 134
 135 /* Server-side transport endpoint wants a whole page for its send
 136  * buffer. The client RPC code constructs the RPC header in this
 137  * buffer before it invokes ->send_request.
 138  */
 139 static int
 140 xprt_rdma_bc_allocate(struct rpc_task *task)
 141 {
 142         struct rpc_rqst *rqst = task->tk_rqstp;
 143         size_t size = rqst->rq_callsize;
 144         struct page *page;
 145
 146         if (size > PAGE_SIZE) {
 147                 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
 148                           size);
 149                 return -EINVAL;
 150         }
 151
 152         page = alloc_page(RPCRDMA_DEF_GFP);
 153         if (!page)
 154                 return -ENOMEM;
 155         rqst->rq_buffer = page_address(page);
 156
 157         rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
 158         if (!rqst->rq_rbuffer) {
 159                 put_page(page);
 160                 return -ENOMEM;
 161         }
 162         return 0;
 163 }
 164
 165 static void
 166 xprt_rdma_bc_free(struct rpc_task *task)
 167 {
 168         struct rpc_rqst *rqst = task->tk_rqstp;
 169
 170         put_page(virt_to_page(rqst->rq_buffer));
 171         kfree(rqst->rq_rbuffer);
 172 }
 173
 174 static int
 175 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
 176 {
 177         struct rpc_xprt *xprt = rqst->rq_xprt;
 178         struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
 179         struct svc_rdma_send_ctxt *ctxt;
 180         __be32 *p;
 181         int rc;
 182
 183         ctxt = svc_rdma_send_ctxt_get(rdma);
 184         if (!ctxt)
 185                 goto drop_connection;
 186
 187         p = ctxt->sc_xprt_buf;
 188         *p++ = rqst->rq_xid;
 189         *p++ = rpcrdma_version;
 190         *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
 191         *p++ = rdma_msg;
 192         *p++ = xdr_zero;
 193         *p++ = xdr_zero;
 194         *p   = xdr_zero;
 195         svc_rdma_sync_reply_hdr(rdma, ctxt, RPCRDMA_HDRLEN_MIN);
 196
 197 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
 198         pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer);
 199 #endif
 200
 201         rc = svc_rdma_bc_sendto(rdma, rqst, ctxt);
 202         if (rc) {
 203                 svc_rdma_send_ctxt_put(rdma, ctxt);
 204                 goto drop_connection;
 205         }
 206         return rc;
 207
 208 drop_connection:
 209         dprintk("svcrdma: failed to send bc call\n");
 210         xprt_disconnect_done(xprt);
 211         return -ENOTCONN;
 212 }
 213
 214 /* Send an RPC call on the passive end of a transport
 215  * connection.
 216  */
 217 static int
 218 xprt_rdma_bc_send_request(struct rpc_rqst *rqst)
 219 {
 220         struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
 221         struct svcxprt_rdma *rdma;
 222         int ret;
 223
 224         dprintk("svcrdma: sending bc call with xid: %08x\n",
 225                 be32_to_cpu(rqst->rq_xid));
 226
 227         mutex_lock(&sxprt->xpt_mutex);
 228
 229         ret = -ENOTCONN;
 230         rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
 231         if (!test_bit(XPT_DEAD, &sxprt->xpt_flags))
 232                 ret = rpcrdma_bc_send_request(rdma, rqst);
 233
 234         mutex_unlock(&sxprt->xpt_mutex);
 235
 236         if (ret < 0)
 237                 return ret;
 238         return 0;
 239 }
 240
 241 static void
 242 xprt_rdma_bc_close(struct rpc_xprt *xprt)
 243 {
 244         dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
 245         xprt->cwnd = RPC_CWNDSHIFT;
 246 }
 247
 248 static void
 249 xprt_rdma_bc_put(struct rpc_xprt *xprt)
 250 {
 251         dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
 252
 253         xprt_free(xprt);
 254         module_put(THIS_MODULE);
 255 }
 256
 257 static const struct rpc_xprt_ops xprt_rdma_bc_procs = {
 258         .reserve_xprt           = xprt_reserve_xprt_cong,
 259         .release_xprt           = xprt_release_xprt_cong,
 260         .alloc_slot             = xprt_alloc_slot,
 261         .free_slot              = xprt_free_slot,
 262         .release_request        = xprt_release_rqst_cong,
 263         .buf_alloc              = xprt_rdma_bc_allocate,
 264         .buf_free               = xprt_rdma_bc_free,
 265         .send_request           = xprt_rdma_bc_send_request,
 266         .set_retrans_timeout    = xprt_set_retrans_timeout_def,
 267         .close                  = xprt_rdma_bc_close,
 268         .destroy                = xprt_rdma_bc_put,
 269         .print_stats            = xprt_rdma_print_stats
 270 };
 271
 272 static const struct rpc_timeout xprt_rdma_bc_timeout = {
 273         .to_initval = 60 * HZ,
 274         .to_maxval = 60 * HZ,
 275 };
 276
 277 /* It shouldn't matter if the number of backchannel session slots
 278  * doesn't match the number of RPC/RDMA credits. That just means
 279  * one or the other will have extra slots that aren't used.
 280  */
 281 static struct rpc_xprt *
 282 xprt_setup_rdma_bc(struct xprt_create *args)
 283 {
 284         struct rpc_xprt *xprt;
 285         struct rpcrdma_xprt *new_xprt;
 286
 287         if (args->addrlen > sizeof(xprt->addr)) {
 288                 dprintk("RPC:       %s: address too large\n", __func__);
 289                 return ERR_PTR(-EBADF);
 290         }
 291
 292         xprt = xprt_alloc(args->net, sizeof(*new_xprt),
 293                           RPCRDMA_MAX_BC_REQUESTS,
 294                           RPCRDMA_MAX_BC_REQUESTS);
 295         if (!xprt) {
 296                 dprintk("RPC:       %s: couldn't allocate rpc_xprt\n",
 297                         __func__);
 298                 return ERR_PTR(-ENOMEM);
 299         }
 300
 301         xprt->timeout = &xprt_rdma_bc_timeout;
 302         xprt_set_bound(xprt);
 303         xprt_set_connected(xprt);
 304         xprt->bind_timeout = RPCRDMA_BIND_TO;
 305         xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
 306         xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO;
 307
 308         xprt->prot = XPRT_TRANSPORT_BC_RDMA;
 309         xprt->tsh_size = 0;
 310         xprt->ops = &xprt_rdma_bc_procs;
 311
 312         memcpy(&xprt->addr, args->dstaddr, args->addrlen);
 313         xprt->addrlen = args->addrlen;
 314         xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
 315         xprt->resvport = 0;
 316
 317         xprt->max_payload = xprt_rdma_max_inline_read;
 318
 319         new_xprt = rpcx_to_rdmax(xprt);
 320         new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
 321
 322         xprt_get(xprt);
 323         args->bc_xprt->xpt_bc_xprt = xprt;
 324         xprt->bc_xprt = args->bc_xprt;
 325
 326         if (!try_module_get(THIS_MODULE))
 327                 goto out_fail;
 328
 329         /* Final put for backchannel xprt is in __svc_rdma_free */
 330         xprt_get(xprt);
 331         return xprt;
 332
 333 out_fail:
 334         xprt_rdma_free_addresses(xprt);
 335         args->bc_xprt->xpt_bc_xprt = NULL;
 336         args->bc_xprt->xpt_bc_xps = NULL;
 337         xprt_put(xprt);
 338         xprt_free(xprt);
 339         return ERR_PTR(-EINVAL);
 340 }
 341
 342 struct xprt_class xprt_rdma_bc = {
 343         .list                   = LIST_HEAD_INIT(xprt_rdma_bc.list),
 344         .name                   = "rdma backchannel",
 345         .owner                  = THIS_MODULE,
 346         .ident                  = XPRT_TRANSPORT_BC_RDMA,
 347         .setup                  = xprt_setup_rdma_bc,
 348 };