root/net/sunrpc/xprtrdma/svc_rdma_backchannel.c

DEFINITIONS

1. svc_rdma_handle_bc_reply
2. svc_rdma_bc_sendto
3. xprt_rdma_bc_allocate
4. xprt_rdma_bc_free
5. rpcrdma_bc_send_request
6. xprt_rdma_bc_send_request
7. xprt_rdma_bc_close
8. xprt_rdma_bc_put
9. xprt_setup_rdma_bc

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