net/sunrpc/xprtrdma/svc_rdma_backchannel.c

   1 /*
   2  * Copyright (c) 2015 Oracle.  All rights reserved.
   3  *
   4  * Support for backward direction RPCs on RPC/RDMA (server-side).
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/sunrpc/svc_rdma.h>
   9 #include "xprt_rdma.h"
  10
  11 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
  12
  13 #undef SVCRDMA_BACKCHANNEL_DEBUG
  14
  15 int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, struct rpcrdma_msg *rmsgp,
  16                              struct xdr_buf *rcvbuf)
  17 {
  18         struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
  19         struct kvec *dst, *src = &rcvbuf->head[0];
  20         struct rpc_rqst *req;
  21         unsigned long cwnd;
  22         u32 credits;
  23         size_t len;
  24         __be32 xid;
  25         __be32 *p;
  26         int ret;
  27
  28         p = (__be32 *)src->iov_base;
  29         len = src->iov_len;
  30         xid = rmsgp->rm_xid;
  31
  32 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
  33         pr_info("%s: xid=%08x, length=%zu\n",
  34                 __func__, be32_to_cpu(xid), len);
  35         pr_info("%s: RPC/RDMA: %*ph\n",
  36                 __func__, (int)RPCRDMA_HDRLEN_MIN, rmsgp);
  37         pr_info("%s:      RPC: %*ph\n",
  38                 __func__, (int)len, p);
  39 #endif
  40
  41         ret = -EAGAIN;
  42         if (src->iov_len < 24)
  43                 goto out_shortreply;
  44
  45         spin_lock_bh(&xprt->transport_lock);
  46         req = xprt_lookup_rqst(xprt, xid);
  47         if (!req)
  48                 goto out_notfound;
  49
  50         dst = &req->rq_private_buf.head[0];
  51         memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
  52         if (dst->iov_len < len)
  53                 goto out_unlock;
  54         memcpy(dst->iov_base, p, len);
  55
  56         credits = be32_to_cpu(rmsgp->rm_credit);
  57         if (credits == 0)
  58                 credits = 1;    /* don't deadlock */
  59         else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
  60                 credits = r_xprt->rx_buf.rb_bc_max_requests;
  61
  62         cwnd = xprt->cwnd;
  63         xprt->cwnd = credits << RPC_CWNDSHIFT;
  64         if (xprt->cwnd > cwnd)
  65                 xprt_release_rqst_cong(req->rq_task);
  66
  67         ret = 0;
  68         xprt_complete_rqst(req->rq_task, rcvbuf->len);
  69         rcvbuf->len = 0;
  70
  71 out_unlock:
  72         spin_unlock_bh(&xprt->transport_lock);
  73 out:
  74         return ret;
  75
  76 out_shortreply:
  77         dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n",
  78                 xprt, src->iov_len);
  79         goto out;
  80
  81 out_notfound:
  82         dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n",
  83                 xprt, be32_to_cpu(xid));
  84
  85         goto out_unlock;
  86 }
  87
  88 /* Send a backwards direction RPC call.
  89  *
  90  * Caller holds the connection's mutex and has already marshaled
  91  * the RPC/RDMA request.
  92  *
  93  * This is similar to svc_rdma_reply, but takes an rpc_rqst
  94  * instead, does not support chunks, and avoids blocking memory
  95  * allocation.
  96  *
  97  * XXX: There is still an opportunity to block in svc_rdma_send()
  98  * if there are no SQ entries to post the Send. This may occur if
  99  * the adapter has a small maximum SQ depth.
 100  */
 101 static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
 102                               struct rpc_rqst *rqst)
 103 {
 104         struct xdr_buf *sndbuf = &rqst->rq_snd_buf;
 105         struct svc_rdma_op_ctxt *ctxt;
 106         struct svc_rdma_req_map *vec;
 107         struct ib_send_wr send_wr;
 108         int ret;
 109
 110         vec = svc_rdma_get_req_map(rdma);
 111         ret = svc_rdma_map_xdr(rdma, sndbuf, vec, false);
 112         if (ret)
 113                 goto out_err;
 114
 115         ret = svc_rdma_repost_recv(rdma, GFP_NOIO);
 116         if (ret)
 117                 goto out_err;
 118
 119         ctxt = svc_rdma_get_context(rdma);
 120         ctxt->pages[0] = virt_to_page(rqst->rq_buffer);
 121         ctxt->count = 1;
 122
 123         ctxt->direction = DMA_TO_DEVICE;
 124         ctxt->sge[0].lkey = rdma->sc_pd->local_dma_lkey;
 125         ctxt->sge[0].length = sndbuf->len;
 126         ctxt->sge[0].addr =
 127             ib_dma_map_page(rdma->sc_cm_id->device, ctxt->pages[0], 0,
 128                             sndbuf->len, DMA_TO_DEVICE);
 129         if (ib_dma_mapping_error(rdma->sc_cm_id->device, ctxt->sge[0].addr)) {
 130                 ret = -EIO;
 131                 goto out_unmap;
 132         }
 133         svc_rdma_count_mappings(rdma, ctxt);
 134
 135         memset(&send_wr, 0, sizeof(send_wr));
 136         ctxt->cqe.done = svc_rdma_wc_send;
 137         send_wr.wr_cqe = &ctxt->cqe;
 138         send_wr.sg_list = ctxt->sge;
 139         send_wr.num_sge = 1;
 140         send_wr.opcode = IB_WR_SEND;
 141         send_wr.send_flags = IB_SEND_SIGNALED;
 142
 143         ret = svc_rdma_send(rdma, &send_wr);
 144         if (ret) {
 145                 ret = -EIO;
 146                 goto out_unmap;
 147         }
 148
 149 out_err:
 150         svc_rdma_put_req_map(rdma, vec);
 151         dprintk("svcrdma: %s returns %d\n", __func__, ret);
 152         return ret;
 153
 154 out_unmap:
 155         svc_rdma_unmap_dma(ctxt);
 156         svc_rdma_put_context(ctxt, 1);
 157         goto out_err;
 158 }
 159
 160 /* Server-side transport endpoint wants a whole page for its send
 161  * buffer. The client RPC code constructs the RPC header in this
 162  * buffer before it invokes ->send_request.
 163  */
 164 static int
 165 xprt_rdma_bc_allocate(struct rpc_task *task)
 166 {
 167         struct rpc_rqst *rqst = task->tk_rqstp;
 168         size_t size = rqst->rq_callsize;
 169         struct page *page;
 170
 171         if (size > PAGE_SIZE) {
 172                 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
 173                           size);
 174                 return -EINVAL;
 175         }
 176
 177         /* svc_rdma_sendto releases this page */
 178         page = alloc_page(RPCRDMA_DEF_GFP);
 179         if (!page)
 180                 return -ENOMEM;
 181         rqst->rq_buffer = page_address(page);
 182
 183         rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
 184         if (!rqst->rq_rbuffer) {
 185                 put_page(page);
 186                 return -ENOMEM;
 187         }
 188         return 0;
 189 }
 190
 191 static void
 192 xprt_rdma_bc_free(struct rpc_task *task)
 193 {
 194         struct rpc_rqst *rqst = task->tk_rqstp;
 195
 196         kfree(rqst->rq_rbuffer);
 197 }
 198
 199 static int
 200 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
 201 {
 202         struct rpc_xprt *xprt = rqst->rq_xprt;
 203         struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
 204         __be32 *p;
 205         int rc;
 206
 207         /* Space in the send buffer for an RPC/RDMA header is reserved
 208          * via xprt->tsh_size.
 209          */
 210         p = rqst->rq_buffer;
 211         *p++ = rqst->rq_xid;
 212         *p++ = rpcrdma_version;
 213         *p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
 214         *p++ = rdma_msg;
 215         *p++ = xdr_zero;
 216         *p++ = xdr_zero;
 217         *p   = xdr_zero;
 218
 219 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
 220         pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer);
 221 #endif
 222
 223         rc = svc_rdma_bc_sendto(rdma, rqst);
 224         if (rc)
 225                 goto drop_connection;
 226         return rc;
 227
 228 drop_connection:
 229         dprintk("svcrdma: failed to send bc call\n");
 230         xprt_disconnect_done(xprt);
 231         return -ENOTCONN;
 232 }
 233
 234 /* Send an RPC call on the passive end of a transport
 235  * connection.
 236  */
 237 static int
 238 xprt_rdma_bc_send_request(struct rpc_task *task)
 239 {
 240         struct rpc_rqst *rqst = task->tk_rqstp;
 241         struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
 242         struct svcxprt_rdma *rdma;
 243         int ret;
 244
 245         dprintk("svcrdma: sending bc call with xid: %08x\n",
 246                 be32_to_cpu(rqst->rq_xid));
 247
 248         if (!mutex_trylock(&sxprt->xpt_mutex)) {
 249                 rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL);
 250                 if (!mutex_trylock(&sxprt->xpt_mutex))
 251                         return -EAGAIN;
 252                 rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task);
 253         }
 254
 255         ret = -ENOTCONN;
 256         rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
 257         if (!test_bit(XPT_DEAD, &sxprt->xpt_flags))
 258                 ret = rpcrdma_bc_send_request(rdma, rqst);
 259
 260         mutex_unlock(&sxprt->xpt_mutex);
 261
 262         if (ret < 0)
 263                 return ret;
 264         return 0;
 265 }
 266
 267 static void
 268 xprt_rdma_bc_close(struct rpc_xprt *xprt)
 269 {
 270         dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
 271 }
 272
 273 static void
 274 xprt_rdma_bc_put(struct rpc_xprt *xprt)
 275 {
 276         dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
 277
 278         xprt_free(xprt);
 279         module_put(THIS_MODULE);
 280 }
 281
 282 static struct rpc_xprt_ops xprt_rdma_bc_procs = {
 283         .reserve_xprt           = xprt_reserve_xprt_cong,
 284         .release_xprt           = xprt_release_xprt_cong,
 285         .alloc_slot             = xprt_alloc_slot,
 286         .release_request        = xprt_release_rqst_cong,
 287         .buf_alloc              = xprt_rdma_bc_allocate,
 288         .buf_free               = xprt_rdma_bc_free,
 289         .send_request           = xprt_rdma_bc_send_request,
 290         .set_retrans_timeout    = xprt_set_retrans_timeout_def,
 291         .close                  = xprt_rdma_bc_close,
 292         .destroy                = xprt_rdma_bc_put,
 293         .print_stats            = xprt_rdma_print_stats
 294 };
 295
 296 static const struct rpc_timeout xprt_rdma_bc_timeout = {
 297         .to_initval = 60 * HZ,
 298         .to_maxval = 60 * HZ,
 299 };
 300
 301 /* It shouldn't matter if the number of backchannel session slots
 302  * doesn't match the number of RPC/RDMA credits. That just means
 303  * one or the other will have extra slots that aren't used.
 304  */
 305 static struct rpc_xprt *
 306 xprt_setup_rdma_bc(struct xprt_create *args)
 307 {
 308         struct rpc_xprt *xprt;
 309         struct rpcrdma_xprt *new_xprt;
 310
 311         if (args->addrlen > sizeof(xprt->addr)) {
 312                 dprintk("RPC:       %s: address too large\n", __func__);
 313                 return ERR_PTR(-EBADF);
 314         }
 315
 316         xprt = xprt_alloc(args->net, sizeof(*new_xprt),
 317                           RPCRDMA_MAX_BC_REQUESTS,
 318                           RPCRDMA_MAX_BC_REQUESTS);
 319         if (!xprt) {
 320                 dprintk("RPC:       %s: couldn't allocate rpc_xprt\n",
 321                         __func__);
 322                 return ERR_PTR(-ENOMEM);
 323         }
 324
 325         xprt->timeout = &xprt_rdma_bc_timeout;
 326         xprt_set_bound(xprt);
 327         xprt_set_connected(xprt);
 328         xprt->bind_timeout = RPCRDMA_BIND_TO;
 329         xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
 330         xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO;
 331
 332         xprt->prot = XPRT_TRANSPORT_BC_RDMA;
 333         xprt->tsh_size = RPCRDMA_HDRLEN_MIN / sizeof(__be32);
 334         xprt->ops = &xprt_rdma_bc_procs;
 335
 336         memcpy(&xprt->addr, args->dstaddr, args->addrlen);
 337         xprt->addrlen = args->addrlen;
 338         xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
 339         xprt->resvport = 0;
 340
 341         xprt->max_payload = xprt_rdma_max_inline_read;
 342
 343         new_xprt = rpcx_to_rdmax(xprt);
 344         new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
 345
 346         xprt_get(xprt);
 347         args->bc_xprt->xpt_bc_xprt = xprt;
 348         xprt->bc_xprt = args->bc_xprt;
 349
 350         if (!try_module_get(THIS_MODULE))
 351                 goto out_fail;
 352
 353         /* Final put for backchannel xprt is in __svc_rdma_free */
 354         xprt_get(xprt);
 355         return xprt;
 356
 357 out_fail:
 358         xprt_rdma_free_addresses(xprt);
 359         args->bc_xprt->xpt_bc_xprt = NULL;
 360         args->bc_xprt->xpt_bc_xps = NULL;
 361         xprt_put(xprt);
 362         xprt_free(xprt);
 363         return ERR_PTR(-EINVAL);
 364 }
 365
 366 struct xprt_class xprt_rdma_bc = {
 367         .list                   = LIST_HEAD_INIT(xprt_rdma_bc.list),
 368         .name                   = "rdma backchannel",
 369         .owner                  = THIS_MODULE,
 370         .ident                  = XPRT_TRANSPORT_BC_RDMA,
 371         .setup                  = xprt_setup_rdma_bc,
 372 };