net/sunrpc/xprtrdma/svc_rdma_recvfrom.c

   1 /*
   2  * Copyright (c) 2005-2006 Network Appliance, Inc. All rights reserved.
   3  *
   4  * This software is available to you under a choice of one of two
   5  * licenses.  You may choose to be licensed under the terms of the GNU
   6  * General Public License (GPL) Version 2, available from the file
   7  * COPYING in the main directory of this source tree, or the BSD-type
   8  * license below:
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  *
  14  *      Redistributions of source code must retain the above copyright
  15  *      notice, this list of conditions and the following disclaimer.
  16  *
  17  *      Redistributions in binary form must reproduce the above
  18  *      copyright notice, this list of conditions and the following
  19  *      disclaimer in the documentation and/or other materials provided
  20  *      with the distribution.
  21  *
  22  *      Neither the name of the Network Appliance, Inc. nor the names of
  23  *      its contributors may be used to endorse or promote products
  24  *      derived from this software without specific prior written
  25  *      permission.
  26  *
  27  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  28  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  29  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  30  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  31  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  32  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  33  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  34  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  35  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  36  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  37  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  38  *
  39  * Author: Tom Tucker <tom@opengridcomputing.com>
  40  */
  41
  42 #include <linux/sunrpc/debug.h>
  43 #include <linux/sunrpc/rpc_rdma.h>
  44 #include <linux/spinlock.h>
  45 #include <asm/unaligned.h>
  46 #include <rdma/ib_verbs.h>
  47 #include <rdma/rdma_cm.h>
  48 #include <linux/sunrpc/svc_rdma.h>
  49
  50 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
  51
  52 /*
  53  * Replace the pages in the rq_argpages array with the pages from the SGE in
  54  * the RDMA_RECV completion. The SGL should contain full pages up until the
  55  * last one.
  56  */
  57 static void rdma_build_arg_xdr(struct svc_rqst *rqstp,
  58                                struct svc_rdma_op_ctxt *ctxt,
  59                                u32 byte_count)
  60 {
  61         struct page *page;
  62         u32 bc;
  63         int sge_no;
  64
  65         /* Swap the page in the SGE with the page in argpages */
  66         page = ctxt->pages[0];
  67         put_page(rqstp->rq_pages[0]);
  68         rqstp->rq_pages[0] = page;
  69
  70         /* Set up the XDR head */
  71         rqstp->rq_arg.head[0].iov_base = page_address(page);
  72         rqstp->rq_arg.head[0].iov_len = min(byte_count, ctxt->sge[0].length);
  73         rqstp->rq_arg.len = byte_count;
  74         rqstp->rq_arg.buflen = byte_count;
  75
  76         /* Compute bytes past head in the SGL */
  77         bc = byte_count - rqstp->rq_arg.head[0].iov_len;
  78
  79         /* If data remains, store it in the pagelist */
  80         rqstp->rq_arg.page_len = bc;
  81         rqstp->rq_arg.page_base = 0;
  82         rqstp->rq_arg.pages = &rqstp->rq_pages[1];
  83         sge_no = 1;
  84         while (bc && sge_no < ctxt->count) {
  85                 page = ctxt->pages[sge_no];
  86                 put_page(rqstp->rq_pages[sge_no]);
  87                 rqstp->rq_pages[sge_no] = page;
  88                 bc -= min(bc, ctxt->sge[sge_no].length);
  89                 rqstp->rq_arg.buflen += ctxt->sge[sge_no].length;
  90                 sge_no++;
  91         }
  92         rqstp->rq_respages = &rqstp->rq_pages[sge_no];
  93
  94         /* We should never run out of SGE because the limit is defined to
  95          * support the max allowed RPC data length
  96          */
  97         BUG_ON(bc && (sge_no == ctxt->count));
  98         BUG_ON((rqstp->rq_arg.head[0].iov_len + rqstp->rq_arg.page_len)
  99                != byte_count);
 100         BUG_ON(rqstp->rq_arg.len != byte_count);
 101
 102         /* If not all pages were used from the SGL, free the remaining ones */
 103         bc = sge_no;
 104         while (sge_no < ctxt->count) {
 105                 page = ctxt->pages[sge_no++];
 106                 put_page(page);
 107         }
 108         ctxt->count = bc;
 109
 110         /* Set up tail */
 111         rqstp->rq_arg.tail[0].iov_base = NULL;
 112         rqstp->rq_arg.tail[0].iov_len = 0;
 113 }
 114
 115 /* Encode a read-chunk-list as an array of IB SGE
 116  *
 117  * Assumptions:
 118  * - chunk[0]->position points to pages[0] at an offset of 0
 119  * - pages[] is not physically or virtually contigous and consists of
 120  *   PAGE_SIZE elements.
 121  *
 122  * Output:
 123  * - sge array pointing into pages[] array.
 124  * - chunk_sge array specifying sge index and count for each
 125  *   chunk in the read list
 126  *
 127  */
 128 static int rdma_rcl_to_sge(struct svcxprt_rdma *xprt,
 129                            struct svc_rqst *rqstp,
 130                            struct svc_rdma_op_ctxt *head,
 131                            struct rpcrdma_msg *rmsgp,
 132                            struct svc_rdma_req_map *rpl_map,
 133                            struct svc_rdma_req_map *chl_map,
 134                            int ch_count,
 135                            int byte_count)
 136 {
 137         int sge_no;
 138         int sge_bytes;
 139         int page_off;
 140         int page_no;
 141         int ch_bytes;
 142         int ch_no;
 143         struct rpcrdma_read_chunk *ch;
 144
 145         sge_no = 0;
 146         page_no = 0;
 147         page_off = 0;
 148         ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];
 149         ch_no = 0;
 150         ch_bytes = ch->rc_target.rs_length;
 151         head->arg.head[0] = rqstp->rq_arg.head[0];
 152         head->arg.tail[0] = rqstp->rq_arg.tail[0];
 153         head->arg.pages = &head->pages[head->count];
 154         head->hdr_count = head->count; /* save count of hdr pages */
 155         head->arg.page_base = 0;
 156         head->arg.page_len = ch_bytes;
 157         head->arg.len = rqstp->rq_arg.len + ch_bytes;
 158         head->arg.buflen = rqstp->rq_arg.buflen + ch_bytes;
 159         head->count++;
 160         chl_map->ch[0].start = 0;
 161         while (byte_count) {
 162                 rpl_map->sge[sge_no].iov_base =
 163                         page_address(rqstp->rq_arg.pages[page_no]) + page_off;
 164                 sge_bytes = min_t(int, PAGE_SIZE-page_off, ch_bytes);
 165                 rpl_map->sge[sge_no].iov_len = sge_bytes;
 166                 /*
 167                  * Don't bump head->count here because the same page
 168                  * may be used by multiple SGE.
 169                  */
 170                 head->arg.pages[page_no] = rqstp->rq_arg.pages[page_no];
 171                 rqstp->rq_respages = &rqstp->rq_arg.pages[page_no+1];
 172
 173                 byte_count -= sge_bytes;
 174                 ch_bytes -= sge_bytes;
 175                 sge_no++;
 176                 /*
 177                  * If all bytes for this chunk have been mapped to an
 178                  * SGE, move to the next SGE
 179                  */
 180                 if (ch_bytes == 0) {
 181                         chl_map->ch[ch_no].count =
 182                                 sge_no - chl_map->ch[ch_no].start;
 183                         ch_no++;
 184                         ch++;
 185                         chl_map->ch[ch_no].start = sge_no;
 186                         ch_bytes = ch->rc_target.rs_length;
 187                         /* If bytes remaining account for next chunk */
 188                         if (byte_count) {
 189                                 head->arg.page_len += ch_bytes;
 190                                 head->arg.len += ch_bytes;
 191                                 head->arg.buflen += ch_bytes;
 192                         }
 193                 }
 194                 /*
 195                  * If this SGE consumed all of the page, move to the
 196                  * next page
 197                  */
 198                 if ((sge_bytes + page_off) == PAGE_SIZE) {
 199                         page_no++;
 200                         page_off = 0;
 201                         /*
 202                          * If there are still bytes left to map, bump
 203                          * the page count
 204                          */
 205                         if (byte_count)
 206                                 head->count++;
 207                 } else
 208                         page_off += sge_bytes;
 209         }
 210         BUG_ON(byte_count != 0);
 211         return sge_no;
 212 }
 213
 214 static void rdma_set_ctxt_sge(struct svcxprt_rdma *xprt,
 215                               struct svc_rdma_op_ctxt *ctxt,
 216                               struct kvec *vec,
 217                               u64 *sgl_offset,
 218                               int count)
 219 {
 220         int i;
 221
 222         ctxt->count = count;
 223         ctxt->direction = DMA_FROM_DEVICE;
 224         for (i = 0; i < count; i++) {
 225                 atomic_inc(&xprt->sc_dma_used);
 226                 ctxt->sge[i].addr =
 227                         ib_dma_map_single(xprt->sc_cm_id->device,
 228                                           vec[i].iov_base, vec[i].iov_len,
 229                                           DMA_FROM_DEVICE);
 230                 ctxt->sge[i].length = vec[i].iov_len;
 231                 ctxt->sge[i].lkey = xprt->sc_phys_mr->lkey;
 232                 *sgl_offset = *sgl_offset + vec[i].iov_len;
 233         }
 234 }
 235
 236 static int rdma_read_max_sge(struct svcxprt_rdma *xprt, int sge_count)
 237 {
 238         if ((RDMA_TRANSPORT_IWARP ==
 239              rdma_node_get_transport(xprt->sc_cm_id->
 240                                      device->node_type))
 241             && sge_count > 1)
 242                 return 1;
 243         else
 244                 return min_t(int, sge_count, xprt->sc_max_sge);
 245 }
 246
 247 /*
 248  * Use RDMA_READ to read data from the advertised client buffer into the
 249  * XDR stream starting at rq_arg.head[0].iov_base.
 250  * Each chunk in the array
 251  * contains the following fields:
 252  * discrim      - '1', This isn't used for data placement
 253  * position     - The xdr stream offset (the same for every chunk)
 254  * handle       - RMR for client memory region
 255  * length       - data transfer length
 256  * offset       - 64 bit tagged offset in remote memory region
 257  *
 258  * On our side, we need to read into a pagelist. The first page immediately
 259  * follows the RPC header.
 260  *
 261  * This function returns:
 262  * 0 - No error and no read-list found.
 263  *
 264  * 1 - Successful read-list processing. The data is not yet in
 265  * the pagelist and therefore the RPC request must be deferred. The
 266  * I/O completion will enqueue the transport again and
 267  * svc_rdma_recvfrom will complete the request.
 268  *
 269  * <0 - Error processing/posting read-list.
 270  *
 271  * NOTE: The ctxt must not be touched after the last WR has been posted
 272  * because the I/O completion processing may occur on another
 273  * processor and free / modify the context. Ne touche pas!
 274  */
 275 static int rdma_read_xdr(struct svcxprt_rdma *xprt,
 276                          struct rpcrdma_msg *rmsgp,
 277                          struct svc_rqst *rqstp,
 278                          struct svc_rdma_op_ctxt *hdr_ctxt)
 279 {
 280         struct ib_send_wr read_wr;
 281         int err = 0;
 282         int ch_no;
 283         int ch_count;
 284         int byte_count;
 285         int sge_count;
 286         u64 sgl_offset;
 287         struct rpcrdma_read_chunk *ch;
 288         struct svc_rdma_op_ctxt *ctxt = NULL;
 289         struct svc_rdma_req_map *rpl_map;
 290         struct svc_rdma_req_map *chl_map;
 291
 292         /* If no read list is present, return 0 */
 293         ch = svc_rdma_get_read_chunk(rmsgp);
 294         if (!ch)
 295                 return 0;
 296
 297         /* Allocate temporary reply and chunk maps */
 298         rpl_map = svc_rdma_get_req_map();
 299         chl_map = svc_rdma_get_req_map();
 300
 301         svc_rdma_rcl_chunk_counts(ch, &ch_count, &byte_count);
 302         if (ch_count > RPCSVC_MAXPAGES)
 303                 return -EINVAL;
 304         sge_count = rdma_rcl_to_sge(xprt, rqstp, hdr_ctxt, rmsgp,
 305                                     rpl_map, chl_map,
 306                                     ch_count, byte_count);
 307         sgl_offset = 0;
 308         ch_no = 0;
 309
 310         for (ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];
 311              ch->rc_discrim != 0; ch++, ch_no++) {
 312 next_sge:
 313                 ctxt = svc_rdma_get_context(xprt);
 314                 ctxt->direction = DMA_FROM_DEVICE;
 315                 clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 316
 317                 /* Prepare READ WR */
 318                 memset(&read_wr, 0, sizeof read_wr);
 319                 ctxt->wr_op = IB_WR_RDMA_READ;
 320                 read_wr.wr_id = (unsigned long)ctxt;
 321                 read_wr.opcode = IB_WR_RDMA_READ;
 322                 read_wr.send_flags = IB_SEND_SIGNALED;
 323                 read_wr.wr.rdma.rkey = ch->rc_target.rs_handle;
 324                 read_wr.wr.rdma.remote_addr =
 325                         get_unaligned(&(ch->rc_target.rs_offset)) +
 326                         sgl_offset;
 327                 read_wr.sg_list = ctxt->sge;
 328                 read_wr.num_sge =
 329                         rdma_read_max_sge(xprt, chl_map->ch[ch_no].count);
 330                 rdma_set_ctxt_sge(xprt, ctxt,
 331                                   &rpl_map->sge[chl_map->ch[ch_no].start],
 332                                   &sgl_offset,
 333                                   read_wr.num_sge);
 334                 if (((ch+1)->rc_discrim == 0) &&
 335                     (read_wr.num_sge == chl_map->ch[ch_no].count)) {
 336                         /*
 337                          * Mark the last RDMA_READ with a bit to
 338                          * indicate all RPC data has been fetched from
 339                          * the client and the RPC needs to be enqueued.
 340                          */
 341                         set_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 342                         ctxt->read_hdr = hdr_ctxt;
 343                 }
 344                 /* Post the read */
 345                 err = svc_rdma_send(xprt, &read_wr);
 346                 if (err) {
 347                         printk(KERN_ERR "svcrdma: Error %d posting RDMA_READ\n",
 348                                err);
 349                         set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
 350                         svc_rdma_put_context(ctxt, 0);
 351                         goto out;
 352                 }
 353                 atomic_inc(&rdma_stat_read);
 354
 355                 if (read_wr.num_sge < chl_map->ch[ch_no].count) {
 356                         chl_map->ch[ch_no].count -= read_wr.num_sge;
 357                         chl_map->ch[ch_no].start += read_wr.num_sge;
 358                         goto next_sge;
 359                 }
 360                 sgl_offset = 0;
 361                 err = 1;
 362         }
 363
 364  out:
 365         svc_rdma_put_req_map(rpl_map);
 366         svc_rdma_put_req_map(chl_map);
 367
 368         /* Detach arg pages. svc_recv will replenish them */
 369         for (ch_no = 0; &rqstp->rq_pages[ch_no] < rqstp->rq_respages; ch_no++)
 370                 rqstp->rq_pages[ch_no] = NULL;
 371
 372         /*
 373          * Detach res pages. svc_release must see a resused count of
 374          * zero or it will attempt to put them.
 375          */
 376         while (rqstp->rq_resused)
 377                 rqstp->rq_respages[--rqstp->rq_resused] = NULL;
 378
 379         return err;
 380 }
 381
 382 static int rdma_read_complete(struct svc_rqst *rqstp,
 383                               struct svc_rdma_op_ctxt *head)
 384 {
 385         int page_no;
 386         int ret;
 387
 388         BUG_ON(!head);
 389
 390         /* Copy RPC pages */
 391         for (page_no = 0; page_no < head->count; page_no++) {
 392                 put_page(rqstp->rq_pages[page_no]);
 393                 rqstp->rq_pages[page_no] = head->pages[page_no];
 394         }
 395         /* Point rq_arg.pages past header */
 396         rqstp->rq_arg.pages = &rqstp->rq_pages[head->hdr_count];
 397         rqstp->rq_arg.page_len = head->arg.page_len;
 398         rqstp->rq_arg.page_base = head->arg.page_base;
 399
 400         /* rq_respages starts after the last arg page */
 401         rqstp->rq_respages = &rqstp->rq_arg.pages[page_no];
 402         rqstp->rq_resused = 0;
 403
 404         /* Rebuild rq_arg head and tail. */
 405         rqstp->rq_arg.head[0] = head->arg.head[0];
 406         rqstp->rq_arg.tail[0] = head->arg.tail[0];
 407         rqstp->rq_arg.len = head->arg.len;
 408         rqstp->rq_arg.buflen = head->arg.buflen;
 409
 410         /* Free the context */
 411         svc_rdma_put_context(head, 0);
 412
 413         /* XXX: What should this be? */
 414         rqstp->rq_prot = IPPROTO_MAX;
 415         svc_xprt_copy_addrs(rqstp, rqstp->rq_xprt);
 416
 417         ret = rqstp->rq_arg.head[0].iov_len
 418                 + rqstp->rq_arg.page_len
 419                 + rqstp->rq_arg.tail[0].iov_len;
 420         dprintk("svcrdma: deferred read ret=%d, rq_arg.len =%d, "
 421                 "rq_arg.head[0].iov_base=%p, rq_arg.head[0].iov_len = %zd\n",
 422                 ret, rqstp->rq_arg.len, rqstp->rq_arg.head[0].iov_base,
 423                 rqstp->rq_arg.head[0].iov_len);
 424
 425         svc_xprt_received(rqstp->rq_xprt);
 426         return ret;
 427 }
 428
 429 /*
 430  * Set up the rqstp thread context to point to the RQ buffer. If
 431  * necessary, pull additional data from the client with an RDMA_READ
 432  * request.
 433  */
 434 int svc_rdma_recvfrom(struct svc_rqst *rqstp)
 435 {
 436         struct svc_xprt *xprt = rqstp->rq_xprt;
 437         struct svcxprt_rdma *rdma_xprt =
 438                 container_of(xprt, struct svcxprt_rdma, sc_xprt);
 439         struct svc_rdma_op_ctxt *ctxt = NULL;
 440         struct rpcrdma_msg *rmsgp;
 441         int ret = 0;
 442         int len;
 443
 444         dprintk("svcrdma: rqstp=%p\n", rqstp);
 445
 446         spin_lock_bh(&rdma_xprt->sc_rq_dto_lock);
 447         if (!list_empty(&rdma_xprt->sc_read_complete_q)) {
 448                 ctxt = list_entry(rdma_xprt->sc_read_complete_q.next,
 449                                   struct svc_rdma_op_ctxt,
 450                                   dto_q);
 451                 list_del_init(&ctxt->dto_q);
 452         }
 453         if (ctxt) {
 454                 spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);
 455                 return rdma_read_complete(rqstp, ctxt);
 456         }
 457
 458         if (!list_empty(&rdma_xprt->sc_rq_dto_q)) {
 459                 ctxt = list_entry(rdma_xprt->sc_rq_dto_q.next,
 460                                   struct svc_rdma_op_ctxt,
 461                                   dto_q);
 462                 list_del_init(&ctxt->dto_q);
 463         } else {
 464                 atomic_inc(&rdma_stat_rq_starve);
 465                 clear_bit(XPT_DATA, &xprt->xpt_flags);
 466                 ctxt = NULL;
 467         }
 468         spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);
 469         if (!ctxt) {
 470                 /* This is the EAGAIN path. The svc_recv routine will
 471                  * return -EAGAIN, the nfsd thread will go to call into
 472                  * svc_recv again and we shouldn't be on the active
 473                  * transport list
 474                  */
 475                 if (test_bit(XPT_CLOSE, &xprt->xpt_flags))
 476                         goto close_out;
 477
 478                 BUG_ON(ret);
 479                 goto out;
 480         }
 481         dprintk("svcrdma: processing ctxt=%p on xprt=%p, rqstp=%p, status=%d\n",
 482                 ctxt, rdma_xprt, rqstp, ctxt->wc_status);
 483         BUG_ON(ctxt->wc_status != IB_WC_SUCCESS);
 484         atomic_inc(&rdma_stat_recv);
 485
 486         /* Build up the XDR from the receive buffers. */
 487         rdma_build_arg_xdr(rqstp, ctxt, ctxt->byte_len);
 488
 489         /* Decode the RDMA header. */
 490         len = svc_rdma_xdr_decode_req(&rmsgp, rqstp);
 491         rqstp->rq_xprt_hlen = len;
 492
 493         /* If the request is invalid, reply with an error */
 494         if (len < 0) {
 495                 if (len == -ENOSYS)
 496                         svc_rdma_send_error(rdma_xprt, rmsgp, ERR_VERS);
 497                 goto close_out;
 498         }
 499
 500         /* Read read-list data. */
 501         ret = rdma_read_xdr(rdma_xprt, rmsgp, rqstp, ctxt);
 502         if (ret > 0) {
 503                 /* read-list posted, defer until data received from client. */
 504                 svc_xprt_received(xprt);
 505                 return 0;
 506         }
 507         if (ret < 0) {
 508                 /* Post of read-list failed, free context. */
 509                 svc_rdma_put_context(ctxt, 1);
 510                 return 0;
 511         }
 512
 513         ret = rqstp->rq_arg.head[0].iov_len
 514                 + rqstp->rq_arg.page_len
 515                 + rqstp->rq_arg.tail[0].iov_len;
 516         svc_rdma_put_context(ctxt, 0);
 517  out:
 518         dprintk("svcrdma: ret = %d, rq_arg.len =%d, "
 519                 "rq_arg.head[0].iov_base=%p, rq_arg.head[0].iov_len = %zd\n",
 520                 ret, rqstp->rq_arg.len,
 521                 rqstp->rq_arg.head[0].iov_base,
 522                 rqstp->rq_arg.head[0].iov_len);
 523         rqstp->rq_prot = IPPROTO_MAX;
 524         svc_xprt_copy_addrs(rqstp, xprt);
 525         svc_xprt_received(xprt);
 526         return ret;
 527
 528  close_out:
 529         if (ctxt)
 530                 svc_rdma_put_context(ctxt, 1);
 531         dprintk("svcrdma: transport %p is closing\n", xprt);
 532         /*
 533          * Set the close bit and enqueue it. svc_recv will see the
 534          * close bit and call svc_xprt_delete
 535          */
 536         set_bit(XPT_CLOSE, &xprt->xpt_flags);
 537         svc_xprt_received(xprt);
 538         return 0;
 539 }