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, false);
 111         if (ret)
 112                 goto out_err;
 113
 114         ret = svc_rdma_repost_recv(rdma, GFP_NOIO);
 115         if (ret)
 116                 goto out_err;
 117
 118         ctxt = svc_rdma_get_context(rdma);
 119         ctxt->pages[0] = virt_to_page(rqst->rq_buffer);
 120         ctxt->count = 1;
 121
 122         ctxt->direction = DMA_TO_DEVICE;
 123         ctxt->sge[0].lkey = rdma->sc_pd->local_dma_lkey;
 124         ctxt->sge[0].length = sndbuf->len;
 125         ctxt->sge[0].addr =
 126             ib_dma_map_page(rdma->sc_cm_id->device, ctxt->pages[0], 0,
 127                             sndbuf->len, DMA_TO_DEVICE);
 128         if (ib_dma_mapping_error(rdma->sc_cm_id->device, ctxt->sge[0].addr)) {
 129                 ret = -EIO;
 130                 goto out_unmap;
 131         }
 132         svc_rdma_count_mappings(rdma, ctxt);
 133
 134         memset(&send_wr, 0, sizeof(send_wr));
 135         ctxt->cqe.done = svc_rdma_wc_send;
 136         send_wr.wr_cqe = &ctxt->cqe;
 137         send_wr.sg_list = ctxt->sge;
 138         send_wr.num_sge = 1;
 139         send_wr.opcode = IB_WR_SEND;
 140         send_wr.send_flags = IB_SEND_SIGNALED;
 141
 142         ret = svc_rdma_send(rdma, &send_wr);
 143         if (ret) {
 144                 ret = -EIO;
 145                 goto out_unmap;
 146         }
 147
 148 out_err:
 149         svc_rdma_put_req_map(rdma, vec);
 150         dprintk("svcrdma: %s returns %d\n", __func__, ret);
 151         return ret;
 152
 153 out_unmap:
 154         svc_rdma_unmap_dma(ctxt);
 155         svc_rdma_put_context(ctxt, 1);
 156         goto out_err;
 157 }
 158
 159 /* Server-side transport endpoint wants a whole page for its send
 160  * buffer. The client RPC code constructs the RPC header in this
 161  * buffer before it invokes ->send_request.
 162  */
 163 static int
 164 xprt_rdma_bc_allocate(struct rpc_task *task)
 165 {
 166         struct rpc_rqst *rqst = task->tk_rqstp;
 167         size_t size = rqst->rq_callsize;
 168         struct page *page;
 169
 170         if (size > PAGE_SIZE) {
 171                 WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
 172                           size);
 173                 return -EINVAL;
 174         }
 175
 176         /* svc_rdma_sendto releases this page */
 177         page = alloc_page(RPCRDMA_DEF_GFP);
 178         if (!page)
 179                 return -ENOMEM;
 180         rqst->rq_buffer = page_address(page);
 181
 182         rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
 183         if (!rqst->rq_rbuffer) {
 184                 put_page(page);
 185                 return -ENOMEM;
 186         }
 187         return 0;
 188 }
 189
 190 static void
 191 xprt_rdma_bc_free(struct rpc_task *task)
 192 {
 193         struct rpc_rqst *rqst = task->tk_rqstp;
 194
 195         kfree(rqst->rq_rbuffer);
 196 }
 197
 198 static int
 199 rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
 200 {
 201         struct rpc_xprt *xprt = rqst->rq_xprt;
 202         struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
 203         struct rpcrdma_msg *headerp = (struct rpcrdma_msg *)rqst->rq_buffer;
 204         int rc;
 205
 206         /* Space in the send buffer for an RPC/RDMA header is reserved
 207          * via xprt->tsh_size.
 208          */
 209         headerp->rm_xid = rqst->rq_xid;
 210         headerp->rm_vers = rpcrdma_version;
 211         headerp->rm_credit = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
 212         headerp->rm_type = rdma_msg;
 213         headerp->rm_body.rm_chunks[0] = xdr_zero;
 214         headerp->rm_body.rm_chunks[1] = xdr_zero;
 215         headerp->rm_body.rm_chunks[2] = xdr_zero;
 216
 217 #ifdef SVCRDMA_BACKCHANNEL_DEBUG
 218         pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer);
 219 #endif
 220
 221         rc = svc_rdma_bc_sendto(rdma, rqst);
 222         if (rc)
 223                 goto drop_connection;
 224         return rc;
 225
 226 drop_connection:
 227         dprintk("svcrdma: failed to send bc call\n");
 228         xprt_disconnect_done(xprt);
 229         return -ENOTCONN;
 230 }
 231
 232 /* Send an RPC call on the passive end of a transport
 233  * connection.
 234  */
 235 static int
 236 xprt_rdma_bc_send_request(struct rpc_task *task)
 237 {
 238         struct rpc_rqst *rqst = task->tk_rqstp;
 239         struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
 240         struct svcxprt_rdma *rdma;
 241         int ret;
 242
 243         dprintk("svcrdma: sending bc call with xid: %08x\n",
 244                 be32_to_cpu(rqst->rq_xid));
 245
 246         if (!mutex_trylock(&sxprt->xpt_mutex)) {
 247                 rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL);
 248                 if (!mutex_trylock(&sxprt->xpt_mutex))
 249                         return -EAGAIN;
 250                 rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task);
 251         }
 252
 253         ret = -ENOTCONN;
 254         rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
 255         if (!test_bit(XPT_DEAD, &sxprt->xpt_flags))
 256                 ret = rpcrdma_bc_send_request(rdma, rqst);
 257
 258         mutex_unlock(&sxprt->xpt_mutex);
 259
 260         if (ret < 0)
 261                 return ret;
 262         return 0;
 263 }
 264
 265 static void
 266 xprt_rdma_bc_close(struct rpc_xprt *xprt)
 267 {
 268         dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
 269 }
 270
 271 static void
 272 xprt_rdma_bc_put(struct rpc_xprt *xprt)
 273 {
 274         dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
 275
 276         xprt_free(xprt);
 277         module_put(THIS_MODULE);
 278 }
 279
 280 static struct rpc_xprt_ops xprt_rdma_bc_procs = {
 281         .reserve_xprt           = xprt_reserve_xprt_cong,
 282         .release_xprt           = xprt_release_xprt_cong,
 283         .alloc_slot             = xprt_alloc_slot,
 284         .release_request        = xprt_release_rqst_cong,
 285         .buf_alloc              = xprt_rdma_bc_allocate,
 286         .buf_free               = xprt_rdma_bc_free,
 287         .send_request           = xprt_rdma_bc_send_request,
 288         .set_retrans_timeout    = xprt_set_retrans_timeout_def,
 289         .close                  = xprt_rdma_bc_close,
 290         .destroy                = xprt_rdma_bc_put,
 291         .print_stats            = xprt_rdma_print_stats
 292 };
 293
 294 static const struct rpc_timeout xprt_rdma_bc_timeout = {
 295         .to_initval = 60 * HZ,
 296         .to_maxval = 60 * HZ,
 297 };
 298
 299 /* It shouldn't matter if the number of backchannel session slots
 300  * doesn't match the number of RPC/RDMA credits. That just means
 301  * one or the other will have extra slots that aren't used.
 302  */
 303 static struct rpc_xprt *
 304 xprt_setup_rdma_bc(struct xprt_create *args)
 305 {
 306         struct rpc_xprt *xprt;
 307         struct rpcrdma_xprt *new_xprt;
 308
 309         if (args->addrlen > sizeof(xprt->addr)) {
 310                 dprintk("RPC:       %s: address too large\n", __func__);
 311                 return ERR_PTR(-EBADF);
 312         }
 313
 314         xprt = xprt_alloc(args->net, sizeof(*new_xprt),
 315                           RPCRDMA_MAX_BC_REQUESTS,
 316                           RPCRDMA_MAX_BC_REQUESTS);
 317         if (!xprt) {
 318                 dprintk("RPC:       %s: couldn't allocate rpc_xprt\n",
 319                         __func__);
 320                 return ERR_PTR(-ENOMEM);
 321         }
 322
 323         xprt->timeout = &xprt_rdma_bc_timeout;
 324         xprt_set_bound(xprt);
 325         xprt_set_connected(xprt);
 326         xprt->bind_timeout = RPCRDMA_BIND_TO;
 327         xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
 328         xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO;
 329
 330         xprt->prot = XPRT_TRANSPORT_BC_RDMA;
 331         xprt->tsh_size = RPCRDMA_HDRLEN_MIN / sizeof(__be32);
 332         xprt->ops = &xprt_rdma_bc_procs;
 333
 334         memcpy(&xprt->addr, args->dstaddr, args->addrlen);
 335         xprt->addrlen = args->addrlen;
 336         xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
 337         xprt->resvport = 0;
 338
 339         xprt->max_payload = xprt_rdma_max_inline_read;
 340
 341         new_xprt = rpcx_to_rdmax(xprt);
 342         new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
 343
 344         xprt_get(xprt);
 345         args->bc_xprt->xpt_bc_xprt = xprt;
 346         xprt->bc_xprt = args->bc_xprt;
 347
 348         if (!try_module_get(THIS_MODULE))
 349                 goto out_fail;
 350
 351         /* Final put for backchannel xprt is in __svc_rdma_free */
 352         xprt_get(xprt);
 353         return xprt;
 354
 355 out_fail:
 356         xprt_rdma_free_addresses(xprt);
 357         args->bc_xprt->xpt_bc_xprt = NULL;
 358         args->bc_xprt->xpt_bc_xps = NULL;
 359         xprt_put(xprt);
 360         xprt_free(xprt);
 361         return ERR_PTR(-EINVAL);
 362 }
 363
 364 struct xprt_class xprt_rdma_bc = {
 365         .list                   = LIST_HEAD_INIT(xprt_rdma_bc.list),
 366         .name                   = "rdma backchannel",
 367         .owner                  = THIS_MODULE,
 368         .ident                  = XPRT_TRANSPORT_BC_RDMA,
 369         .setup                  = xprt_setup_rdma_bc,
 370 };