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/sunrpc/svc_rdma.h>
   8 #include "xprt_rdma.h"
   9
  10 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
  11
  12 #undef SVCRDMA_BACKCHANNEL_DEBUG
  13
  14 int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, struct rpcrdma_msg *rmsgp,
  15                              struct xdr_buf *rcvbuf)
  16 {
  17         struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
  18         struct kvec *dst, *src = &rcvbuf->head[0];
  19         struct rpc_rqst *req;
  20         unsigned long cwnd;
  21         u32 credits;
  22         size_t len;
  23         __be32 xid;
  24         __be32 *p;
  25         int ret;
  26
  27         p = (__be32 *)src->iov_base;
  28         len = src->iov_len;
  29         xid = rmsgp->rm_xid;
  30
  31 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
  32         pr_info("%s: xid=%08x, length=%zu\n",
  33                 __func__, be32_to_cpu(xid), len);
  34         pr_info("%s: RPC/RDMA: %*ph\n",
  35                 __func__, (int)RPCRDMA_HDRLEN_MIN, rmsgp);
  36         pr_info("%s:      RPC: %*ph\n",
  37                 __func__, (int)len, p);
  38 #endif
  39
  40         ret = -EAGAIN;
  41         if (src->iov_len < 24)
  42                 goto out_shortreply;
  43
  44         spin_lock_bh(&xprt->transport_lock);
  45         req = xprt_lookup_rqst(xprt, xid);
  46         if (!req)
  47                 goto out_notfound;
  48
  49         dst = &req->rq_private_buf.head[0];
  50         memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
  51         if (dst->iov_len < len)
  52                 goto out_unlock;
  53         memcpy(dst->iov_base, p, len);
  54
  55         credits = be32_to_cpu(rmsgp->rm_credit);
  56         if (credits == 0)
  57                 credits = 1;    /* don't deadlock */
  58         else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
  59                 credits = r_xprt->rx_buf.rb_bc_max_requests;
  60
  61         cwnd = xprt->cwnd;
  62         xprt->cwnd = credits << RPC_CWNDSHIFT;
  63         if (xprt->cwnd > cwnd)
  64                 xprt_release_rqst_cong(req->rq_task);
  65
  66         ret = 0;
  67         xprt_complete_rqst(req->rq_task, rcvbuf->len);
  68         rcvbuf->len = 0;
  69
  70 out_unlock:
  71         spin_unlock_bh(&xprt->transport_lock);
  72 out:
  73         return ret;
  74
  75 out_shortreply:
  76         dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n",
  77                 xprt, src->iov_len);
  78         goto out;
  79
  80 out_notfound:
  81         dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n",
  82                 xprt, be32_to_cpu(xid));
  83
  84         goto out_unlock;
  85 }
  86
  87 /* Send a backwards direction RPC call.
  88  *
  89  * Caller holds the connection's mutex and has already marshaled
  90  * the RPC/RDMA request.
  91  *
  92  * This is similar to svc_rdma_reply, but takes an rpc_rqst
  93  * instead, does not support chunks, and avoids blocking memory
  94  * allocation.
  95  *
  96  * XXX: There is still an opportunity to block in svc_rdma_send()
  97  * if there are no SQ entries to post the Send. This may occur if
  98  * the adapter has a small maximum SQ depth.
  99  */
 100 static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
 101                               struct rpc_rqst *rqst)
 102 {
 103         struct xdr_buf *sndbuf = &rqst->rq_snd_buf;
 104         struct svc_rdma_op_ctxt *ctxt;
 105         struct svc_rdma_req_map *vec;
 106         struct ib_send_wr send_wr;
 107         int ret;
 108
 109         vec = svc_rdma_get_req_map(rdma);
 110         ret = svc_rdma_map_xdr(rdma, sndbuf, vec);
 111         if (ret)
 112                 goto out_err;
 113
 114         /* Post a recv buffer to handle the reply for this request. */
 115         ret = svc_rdma_post_recv(rdma, GFP_NOIO);
 116         if (ret) {
 117                 pr_err("svcrdma: Failed to post bc receive buffer, err=%d.\n",
 118                        ret);
 119                 pr_err("svcrdma: closing transport %p.\n", rdma);
 120                 set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
 121                 ret = -ENOTCONN;
 122                 goto out_err;
 123         }
 124
 125         ctxt = svc_rdma_get_context(rdma);
 126         ctxt->pages[0] = virt_to_page(rqst->rq_buffer);
 127         ctxt->count = 1;
 128
 129         ctxt->wr_op = IB_WR_SEND;
 130         ctxt->direction = DMA_TO_DEVICE;
 131         ctxt->sge[0].lkey = rdma->sc_pd->local_dma_lkey;
 132         ctxt->sge[0].length = sndbuf->len;
 133         ctxt->sge[0].addr =
 134             ib_dma_map_page(rdma->sc_cm_id->device, ctxt->pages[0], 0,
 135                             sndbuf->len, DMA_TO_DEVICE);
 136         if (ib_dma_mapping_error(rdma->sc_cm_id->device, ctxt->sge[0].addr)) {
 137                 ret = -EIO;
 138                 goto out_unmap;
 139         }
 140         atomic_inc(&rdma->sc_dma_used);
 141
 142         memset(&send_wr, 0, sizeof(send_wr));
 143         send_wr.wr_id = (unsigned long)ctxt;
 144         send_wr.sg_list = ctxt->sge;
 145         send_wr.num_sge = 1;
 146         send_wr.opcode = IB_WR_SEND;
 147         send_wr.send_flags = IB_SEND_SIGNALED;
 148
 149         ret = svc_rdma_send(rdma, &send_wr);
 150         if (ret) {
 151                 ret = -EIO;
 152                 goto out_unmap;
 153         }
 154
 155 out_err:
 156         svc_rdma_put_req_map(rdma, vec);
 157         dprintk("svcrdma: %s returns %d\n", __func__, ret);
 158         return ret;
 159
 160 out_unmap:
 161         svc_rdma_unmap_dma(ctxt);
 162         svc_rdma_put_context(ctxt, 1);
 163         goto out_err;
 164 }
 165
 166 /* Server-side transport endpoint wants a whole page for its send
 167  * buffer. The client RPC code constructs the RPC header in this
 168  * buffer before it invokes ->send_request.
 169  *
 170  * Returns NULL if there was a temporary allocation failure.
 171  */
 172 static void *
 173 xprt_rdma_bc_allocate(struct rpc_task *task, size_t size)
 174 {
 175         struct rpc_rqst *rqst = task->tk_rqstp;
 176         struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
 177         struct svcxprt_rdma *rdma;
 178         struct page *page;
 179
 180         rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
 181
 182         /* Prevent an infinite loop: try to make this case work */
 183         if (size > PAGE_SIZE)
 184                 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
 185                           size);
 186
 187         page = alloc_page(RPCRDMA_DEF_GFP);
 188         if (!page)
 189                 return NULL;
 190
 191         return page_address(page);
 192 }
 193
 194 static void
 195 xprt_rdma_bc_free(void *buffer)
 196 {
 197         /* No-op: ctxt and page have already been freed. */
 198 }
 199
 200 static int
 201 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
 202 {
 203         struct rpc_xprt *xprt = rqst->rq_xprt;
 204         struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
 205         struct rpcrdma_msg *headerp = (struct rpcrdma_msg *)rqst->rq_buffer;
 206         int rc;
 207
 208         /* Space in the send buffer for an RPC/RDMA header is reserved
 209          * via xprt->tsh_size.
 210          */
 211         headerp->rm_xid = rqst->rq_xid;
 212         headerp->rm_vers = rpcrdma_version;
 213         headerp->rm_credit = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
 214         headerp->rm_type = rdma_msg;
 215         headerp->rm_body.rm_chunks[0] = xdr_zero;
 216         headerp->rm_body.rm_chunks[1] = xdr_zero;
 217         headerp->rm_body.rm_chunks[2] = 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         xprt_put(xprt);
 361         xprt_free(xprt);
 362         return ERR_PTR(-EINVAL);
 363 }
 364
 365 struct xprt_class xprt_rdma_bc = {
 366         .list                   = LIST_HEAD_INIT(xprt_rdma_bc.list),
 367         .name                   = "rdma backchannel",
 368         .owner                  = THIS_MODULE,
 369         .ident                  = XPRT_TRANSPORT_BC_RDMA,
 370         .setup                  = xprt_setup_rdma_bc,
 371 };