net/sunrpc/xprtrdma/svc_rdma_recvfrom.c

   1 /*
   2  * Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved.
   3  * Copyright (c) 2005-2006 Network Appliance, Inc. All rights reserved.
   4  *
   5  * This software is available to you under a choice of one of two
   6  * licenses.  You may choose to be licensed under the terms of the GNU
   7  * General Public License (GPL) Version 2, available from the file
   8  * COPYING in the main directory of this source tree, or the BSD-type
   9  * license below:
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  *
  15  *      Redistributions of source code must retain the above copyright
  16  *      notice, this list of conditions and the following disclaimer.
  17  *
  18  *      Redistributions in binary form must reproduce the above
  19  *      copyright notice, this list of conditions and the following
  20  *      disclaimer in the documentation and/or other materials provided
  21  *      with the distribution.
  22  *
  23  *      Neither the name of the Network Appliance, Inc. nor the names of
  24  *      its contributors may be used to endorse or promote products
  25  *      derived from this software without specific prior written
  26  *      permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  29  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  30  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  31  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  32  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  33  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  34  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  35  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  36  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  37  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  38  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  39  *
  40  * Author: Tom Tucker <tom@opengridcomputing.com>
  41  */
  42
  43 #include <linux/sunrpc/debug.h>
  44 #include <linux/sunrpc/rpc_rdma.h>
  45 #include <linux/spinlock.h>
  46 #include <asm/unaligned.h>
  47 #include <rdma/ib_verbs.h>
  48 #include <rdma/rdma_cm.h>
  49 #include <linux/sunrpc/svc_rdma.h>
  50
  51 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
  52
  53 /*
  54  * Replace the pages in the rq_argpages array with the pages from the SGE in
  55  * the RDMA_RECV completion. The SGL should contain full pages up until the
  56  * last one.
  57  */
  58 static void rdma_build_arg_xdr(struct svc_rqst *rqstp,
  59                                struct svc_rdma_op_ctxt *ctxt,
  60                                u32 byte_count)
  61 {
  62         struct rpcrdma_msg *rmsgp;
  63         struct page *page;
  64         u32 bc;
  65         int sge_no;
  66
  67         /* Swap the page in the SGE with the page in argpages */
  68         page = ctxt->pages[0];
  69         put_page(rqstp->rq_pages[0]);
  70         rqstp->rq_pages[0] = page;
  71
  72         /* Set up the XDR head */
  73         rqstp->rq_arg.head[0].iov_base = page_address(page);
  74         rqstp->rq_arg.head[0].iov_len =
  75                 min_t(size_t, byte_count, ctxt->sge[0].length);
  76         rqstp->rq_arg.len = byte_count;
  77         rqstp->rq_arg.buflen = byte_count;
  78
  79         /* Compute bytes past head in the SGL */
  80         bc = byte_count - rqstp->rq_arg.head[0].iov_len;
  81
  82         /* If data remains, store it in the pagelist */
  83         rqstp->rq_arg.page_len = bc;
  84         rqstp->rq_arg.page_base = 0;
  85
  86         /* RDMA_NOMSG: RDMA READ data should land just after RDMA RECV data */
  87         rmsgp = (struct rpcrdma_msg *)rqstp->rq_arg.head[0].iov_base;
  88         if (rmsgp->rm_type == rdma_nomsg)
  89                 rqstp->rq_arg.pages = &rqstp->rq_pages[0];
  90         else
  91                 rqstp->rq_arg.pages = &rqstp->rq_pages[1];
  92
  93         sge_no = 1;
  94         while (bc && sge_no < ctxt->count) {
  95                 page = ctxt->pages[sge_no];
  96                 put_page(rqstp->rq_pages[sge_no]);
  97                 rqstp->rq_pages[sge_no] = page;
  98                 bc -= min_t(u32, bc, ctxt->sge[sge_no].length);
  99                 rqstp->rq_arg.buflen += ctxt->sge[sge_no].length;
 100                 sge_no++;
 101         }
 102         rqstp->rq_respages = &rqstp->rq_pages[sge_no];
 103         rqstp->rq_next_page = rqstp->rq_respages + 1;
 104
 105         /* If not all pages were used from the SGL, free the remaining ones */
 106         bc = sge_no;
 107         while (sge_no < ctxt->count) {
 108                 page = ctxt->pages[sge_no++];
 109                 put_page(page);
 110         }
 111         ctxt->count = bc;
 112
 113         /* Set up tail */
 114         rqstp->rq_arg.tail[0].iov_base = NULL;
 115         rqstp->rq_arg.tail[0].iov_len = 0;
 116 }
 117
 118 /* Issue an RDMA_READ using the local lkey to map the data sink */
 119 int rdma_read_chunk_lcl(struct svcxprt_rdma *xprt,
 120                         struct svc_rqst *rqstp,
 121                         struct svc_rdma_op_ctxt *head,
 122                         int *page_no,
 123                         u32 *page_offset,
 124                         u32 rs_handle,
 125                         u32 rs_length,
 126                         u64 rs_offset,
 127                         bool last)
 128 {
 129         struct ib_rdma_wr read_wr;
 130         int pages_needed = PAGE_ALIGN(*page_offset + rs_length) >> PAGE_SHIFT;
 131         struct svc_rdma_op_ctxt *ctxt = svc_rdma_get_context(xprt);
 132         int ret, read, pno;
 133         u32 pg_off = *page_offset;
 134         u32 pg_no = *page_no;
 135
 136         ctxt->direction = DMA_FROM_DEVICE;
 137         ctxt->read_hdr = head;
 138         pages_needed = min_t(int, pages_needed, xprt->sc_max_sge_rd);
 139         read = min_t(int, pages_needed << PAGE_SHIFT, rs_length);
 140
 141         for (pno = 0; pno < pages_needed; pno++) {
 142                 int len = min_t(int, rs_length, PAGE_SIZE - pg_off);
 143
 144                 head->arg.pages[pg_no] = rqstp->rq_arg.pages[pg_no];
 145                 head->arg.page_len += len;
 146                 head->arg.len += len;
 147                 if (!pg_off)
 148                         head->count++;
 149                 rqstp->rq_respages = &rqstp->rq_arg.pages[pg_no+1];
 150                 rqstp->rq_next_page = rqstp->rq_respages + 1;
 151                 ctxt->sge[pno].addr =
 152                         ib_dma_map_page(xprt->sc_cm_id->device,
 153                                         head->arg.pages[pg_no], pg_off,
 154                                         PAGE_SIZE - pg_off,
 155                                         DMA_FROM_DEVICE);
 156                 ret = ib_dma_mapping_error(xprt->sc_cm_id->device,
 157                                            ctxt->sge[pno].addr);
 158                 if (ret)
 159                         goto err;
 160                 atomic_inc(&xprt->sc_dma_used);
 161
 162                 /* The lkey here is either a local dma lkey or a dma_mr lkey */
 163                 ctxt->sge[pno].lkey = xprt->sc_dma_lkey;
 164                 ctxt->sge[pno].length = len;
 165                 ctxt->count++;
 166
 167                 /* adjust offset and wrap to next page if needed */
 168                 pg_off += len;
 169                 if (pg_off == PAGE_SIZE) {
 170                         pg_off = 0;
 171                         pg_no++;
 172                 }
 173                 rs_length -= len;
 174         }
 175
 176         if (last && rs_length == 0)
 177                 set_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 178         else
 179                 clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 180
 181         memset(&read_wr, 0, sizeof(read_wr));
 182         read_wr.wr.wr_id = (unsigned long)ctxt;
 183         read_wr.wr.opcode = IB_WR_RDMA_READ;
 184         ctxt->wr_op = read_wr.wr.opcode;
 185         read_wr.wr.send_flags = IB_SEND_SIGNALED;
 186         read_wr.rkey = rs_handle;
 187         read_wr.remote_addr = rs_offset;
 188         read_wr.wr.sg_list = ctxt->sge;
 189         read_wr.wr.num_sge = pages_needed;
 190
 191         ret = svc_rdma_send(xprt, &read_wr.wr);
 192         if (ret) {
 193                 pr_err("svcrdma: Error %d posting RDMA_READ\n", ret);
 194                 set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
 195                 goto err;
 196         }
 197
 198         /* return current location in page array */
 199         *page_no = pg_no;
 200         *page_offset = pg_off;
 201         ret = read;
 202         atomic_inc(&rdma_stat_read);
 203         return ret;
 204  err:
 205         svc_rdma_unmap_dma(ctxt);
 206         svc_rdma_put_context(ctxt, 0);
 207         return ret;
 208 }
 209
 210 /* Issue an RDMA_READ using an FRMR to map the data sink */
 211 int rdma_read_chunk_frmr(struct svcxprt_rdma *xprt,
 212                          struct svc_rqst *rqstp,
 213                          struct svc_rdma_op_ctxt *head,
 214                          int *page_no,
 215                          u32 *page_offset,
 216                          u32 rs_handle,
 217                          u32 rs_length,
 218                          u64 rs_offset,
 219                          bool last)
 220 {
 221         struct ib_rdma_wr read_wr;
 222         struct ib_send_wr inv_wr;
 223         struct ib_reg_wr reg_wr;
 224         u8 key;
 225         int nents = PAGE_ALIGN(*page_offset + rs_length) >> PAGE_SHIFT;
 226         struct svc_rdma_op_ctxt *ctxt = svc_rdma_get_context(xprt);
 227         struct svc_rdma_fastreg_mr *frmr = svc_rdma_get_frmr(xprt);
 228         int ret, read, pno, dma_nents, n;
 229         u32 pg_off = *page_offset;
 230         u32 pg_no = *page_no;
 231
 232         if (IS_ERR(frmr))
 233                 return -ENOMEM;
 234
 235         ctxt->direction = DMA_FROM_DEVICE;
 236         ctxt->frmr = frmr;
 237         nents = min_t(unsigned int, nents, xprt->sc_frmr_pg_list_len);
 238         read = min_t(int, nents << PAGE_SHIFT, rs_length);
 239
 240         frmr->direction = DMA_FROM_DEVICE;
 241         frmr->access_flags = (IB_ACCESS_LOCAL_WRITE|IB_ACCESS_REMOTE_WRITE);
 242         frmr->sg_nents = nents;
 243
 244         for (pno = 0; pno < nents; pno++) {
 245                 int len = min_t(int, rs_length, PAGE_SIZE - pg_off);
 246
 247                 head->arg.pages[pg_no] = rqstp->rq_arg.pages[pg_no];
 248                 head->arg.page_len += len;
 249                 head->arg.len += len;
 250                 if (!pg_off)
 251                         head->count++;
 252
 253                 sg_set_page(&frmr->sg[pno], rqstp->rq_arg.pages[pg_no],
 254                             len, pg_off);
 255
 256                 rqstp->rq_respages = &rqstp->rq_arg.pages[pg_no+1];
 257                 rqstp->rq_next_page = rqstp->rq_respages + 1;
 258
 259                 /* adjust offset and wrap to next page if needed */
 260                 pg_off += len;
 261                 if (pg_off == PAGE_SIZE) {
 262                         pg_off = 0;
 263                         pg_no++;
 264                 }
 265                 rs_length -= len;
 266         }
 267
 268         if (last && rs_length == 0)
 269                 set_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 270         else
 271                 clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 272
 273         dma_nents = ib_dma_map_sg(xprt->sc_cm_id->device,
 274                                   frmr->sg, frmr->sg_nents,
 275                                   frmr->direction);
 276         if (!dma_nents) {
 277                 pr_err("svcrdma: failed to dma map sg %p\n",
 278                        frmr->sg);
 279                 return -ENOMEM;
 280         }
 281         atomic_inc(&xprt->sc_dma_used);
 282
 283         n = ib_map_mr_sg(frmr->mr, frmr->sg, frmr->sg_nents, PAGE_SIZE);
 284         if (unlikely(n != frmr->sg_nents)) {
 285                 pr_err("svcrdma: failed to map mr %p (%d/%d elements)\n",
 286                        frmr->mr, n, frmr->sg_nents);
 287                 return n < 0 ? n : -EINVAL;
 288         }
 289
 290         /* Bump the key */
 291         key = (u8)(frmr->mr->lkey & 0x000000FF);
 292         ib_update_fast_reg_key(frmr->mr, ++key);
 293
 294         ctxt->sge[0].addr = frmr->mr->iova;
 295         ctxt->sge[0].lkey = frmr->mr->lkey;
 296         ctxt->sge[0].length = frmr->mr->length;
 297         ctxt->count = 1;
 298         ctxt->read_hdr = head;
 299
 300         /* Prepare REG WR */
 301         reg_wr.wr.opcode = IB_WR_REG_MR;
 302         reg_wr.wr.wr_id = 0;
 303         reg_wr.wr.send_flags = IB_SEND_SIGNALED;
 304         reg_wr.wr.num_sge = 0;
 305         reg_wr.mr = frmr->mr;
 306         reg_wr.key = frmr->mr->lkey;
 307         reg_wr.access = frmr->access_flags;
 308         reg_wr.wr.next = &read_wr.wr;
 309
 310         /* Prepare RDMA_READ */
 311         memset(&read_wr, 0, sizeof(read_wr));
 312         read_wr.wr.send_flags = IB_SEND_SIGNALED;
 313         read_wr.rkey = rs_handle;
 314         read_wr.remote_addr = rs_offset;
 315         read_wr.wr.sg_list = ctxt->sge;
 316         read_wr.wr.num_sge = 1;
 317         if (xprt->sc_dev_caps & SVCRDMA_DEVCAP_READ_W_INV) {
 318                 read_wr.wr.opcode = IB_WR_RDMA_READ_WITH_INV;
 319                 read_wr.wr.wr_id = (unsigned long)ctxt;
 320                 read_wr.wr.ex.invalidate_rkey = ctxt->frmr->mr->lkey;
 321         } else {
 322                 read_wr.wr.opcode = IB_WR_RDMA_READ;
 323                 read_wr.wr.next = &inv_wr;
 324                 /* Prepare invalidate */
 325                 memset(&inv_wr, 0, sizeof(inv_wr));
 326                 inv_wr.wr_id = (unsigned long)ctxt;
 327                 inv_wr.opcode = IB_WR_LOCAL_INV;
 328                 inv_wr.send_flags = IB_SEND_SIGNALED | IB_SEND_FENCE;
 329                 inv_wr.ex.invalidate_rkey = frmr->mr->lkey;
 330         }
 331         ctxt->wr_op = read_wr.wr.opcode;
 332
 333         /* Post the chain */
 334         ret = svc_rdma_send(xprt, &reg_wr.wr);
 335         if (ret) {
 336                 pr_err("svcrdma: Error %d posting RDMA_READ\n", ret);
 337                 set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
 338                 goto err;
 339         }
 340
 341         /* return current location in page array */
 342         *page_no = pg_no;
 343         *page_offset = pg_off;
 344         ret = read;
 345         atomic_inc(&rdma_stat_read);
 346         return ret;
 347  err:
 348         ib_dma_unmap_sg(xprt->sc_cm_id->device,
 349                         frmr->sg, frmr->sg_nents, frmr->direction);
 350         svc_rdma_put_context(ctxt, 0);
 351         svc_rdma_put_frmr(xprt, frmr);
 352         return ret;
 353 }
 354
 355 static unsigned int
 356 rdma_rcl_chunk_count(struct rpcrdma_read_chunk *ch)
 357 {
 358         unsigned int count;
 359
 360         for (count = 0; ch->rc_discrim != xdr_zero; ch++)
 361                 count++;
 362         return count;
 363 }
 364
 365 /* If there was additional inline content, append it to the end of arg.pages.
 366  * Tail copy has to be done after the reader function has determined how many
 367  * pages are needed for RDMA READ.
 368  */
 369 static int
 370 rdma_copy_tail(struct svc_rqst *rqstp, struct svc_rdma_op_ctxt *head,
 371                u32 position, u32 byte_count, u32 page_offset, int page_no)
 372 {
 373         char *srcp, *destp;
 374         int ret;
 375
 376         ret = 0;
 377         srcp = head->arg.head[0].iov_base + position;
 378         byte_count = head->arg.head[0].iov_len - position;
 379         if (byte_count > PAGE_SIZE) {
 380                 dprintk("svcrdma: large tail unsupported\n");
 381                 return 0;
 382         }
 383
 384         /* Fit as much of the tail on the current page as possible */
 385         if (page_offset != PAGE_SIZE) {
 386                 destp = page_address(rqstp->rq_arg.pages[page_no]);
 387                 destp += page_offset;
 388                 while (byte_count--) {
 389                         *destp++ = *srcp++;
 390                         page_offset++;
 391                         if (page_offset == PAGE_SIZE && byte_count)
 392                                 goto more;
 393                 }
 394                 goto done;
 395         }
 396
 397 more:
 398         /* Fit the rest on the next page */
 399         page_no++;
 400         destp = page_address(rqstp->rq_arg.pages[page_no]);
 401         while (byte_count--)
 402                 *destp++ = *srcp++;
 403
 404         rqstp->rq_respages = &rqstp->rq_arg.pages[page_no+1];
 405         rqstp->rq_next_page = rqstp->rq_respages + 1;
 406
 407 done:
 408         byte_count = head->arg.head[0].iov_len - position;
 409         head->arg.page_len += byte_count;
 410         head->arg.len += byte_count;
 411         head->arg.buflen += byte_count;
 412         return 1;
 413 }
 414
 415 static int rdma_read_chunks(struct svcxprt_rdma *xprt,
 416                             struct rpcrdma_msg *rmsgp,
 417                             struct svc_rqst *rqstp,
 418                             struct svc_rdma_op_ctxt *head)
 419 {
 420         int page_no, ret;
 421         struct rpcrdma_read_chunk *ch;
 422         u32 handle, page_offset, byte_count;
 423         u32 position;
 424         u64 rs_offset;
 425         bool last;
 426
 427         /* If no read list is present, return 0 */
 428         ch = svc_rdma_get_read_chunk(rmsgp);
 429         if (!ch)
 430                 return 0;
 431
 432         if (rdma_rcl_chunk_count(ch) > RPCSVC_MAXPAGES)
 433                 return -EINVAL;
 434
 435         /* The request is completed when the RDMA_READs complete. The
 436          * head context keeps all the pages that comprise the
 437          * request.
 438          */
 439         head->arg.head[0] = rqstp->rq_arg.head[0];
 440         head->arg.tail[0] = rqstp->rq_arg.tail[0];
 441         head->hdr_count = head->count;
 442         head->arg.page_base = 0;
 443         head->arg.page_len = 0;
 444         head->arg.len = rqstp->rq_arg.len;
 445         head->arg.buflen = rqstp->rq_arg.buflen;
 446
 447         ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];
 448         position = be32_to_cpu(ch->rc_position);
 449
 450         /* RDMA_NOMSG: RDMA READ data should land just after RDMA RECV data */
 451         if (position == 0) {
 452                 head->arg.pages = &head->pages[0];
 453                 page_offset = head->byte_len;
 454         } else {
 455                 head->arg.pages = &head->pages[head->count];
 456                 page_offset = 0;
 457         }
 458
 459         ret = 0;
 460         page_no = 0;
 461         for (; ch->rc_discrim != xdr_zero; ch++) {
 462                 if (be32_to_cpu(ch->rc_position) != position)
 463                         goto err;
 464
 465                 handle = be32_to_cpu(ch->rc_target.rs_handle),
 466                 byte_count = be32_to_cpu(ch->rc_target.rs_length);
 467                 xdr_decode_hyper((__be32 *)&ch->rc_target.rs_offset,
 468                                  &rs_offset);
 469
 470                 while (byte_count > 0) {
 471                         last = (ch + 1)->rc_discrim == xdr_zero;
 472                         ret = xprt->sc_reader(xprt, rqstp, head,
 473                                               &page_no, &page_offset,
 474                                               handle, byte_count,
 475                                               rs_offset, last);
 476                         if (ret < 0)
 477                                 goto err;
 478                         byte_count -= ret;
 479                         rs_offset += ret;
 480                         head->arg.buflen += ret;
 481                 }
 482         }
 483
 484         /* Read list may need XDR round-up (see RFC 5666, s. 3.7) */
 485         if (page_offset & 3) {
 486                 u32 pad = 4 - (page_offset & 3);
 487
 488                 head->arg.page_len += pad;
 489                 head->arg.len += pad;
 490                 head->arg.buflen += pad;
 491                 page_offset += pad;
 492         }
 493
 494         ret = 1;
 495         if (position && position < head->arg.head[0].iov_len)
 496                 ret = rdma_copy_tail(rqstp, head, position,
 497                                      byte_count, page_offset, page_no);
 498         head->arg.head[0].iov_len = position;
 499         head->position = position;
 500
 501  err:
 502         /* Detach arg pages. svc_recv will replenish them */
 503         for (page_no = 0;
 504              &rqstp->rq_pages[page_no] < rqstp->rq_respages; page_no++)
 505                 rqstp->rq_pages[page_no] = NULL;
 506
 507         return ret;
 508 }
 509
 510 static int rdma_read_complete(struct svc_rqst *rqstp,
 511                               struct svc_rdma_op_ctxt *head)
 512 {
 513         int page_no;
 514         int ret;
 515
 516         /* Copy RPC pages */
 517         for (page_no = 0; page_no < head->count; page_no++) {
 518                 put_page(rqstp->rq_pages[page_no]);
 519                 rqstp->rq_pages[page_no] = head->pages[page_no];
 520         }
 521
 522         /* Adjustments made for RDMA_NOMSG type requests */
 523         if (head->position == 0) {
 524                 if (head->arg.len <= head->sge[0].length) {
 525                         head->arg.head[0].iov_len = head->arg.len -
 526                                                         head->byte_len;
 527                         head->arg.page_len = 0;
 528                 } else {
 529                         head->arg.head[0].iov_len = head->sge[0].length -
 530                                                                 head->byte_len;
 531                         head->arg.page_len = head->arg.len -
 532                                                 head->sge[0].length;
 533                 }
 534         }
 535
 536         /* Point rq_arg.pages past header */
 537         rqstp->rq_arg.pages = &rqstp->rq_pages[head->hdr_count];
 538         rqstp->rq_arg.page_len = head->arg.page_len;
 539         rqstp->rq_arg.page_base = head->arg.page_base;
 540
 541         /* rq_respages starts after the last arg page */
 542         rqstp->rq_respages = &rqstp->rq_arg.pages[page_no];
 543         rqstp->rq_next_page = rqstp->rq_respages + 1;
 544
 545         /* Rebuild rq_arg head and tail. */
 546         rqstp->rq_arg.head[0] = head->arg.head[0];
 547         rqstp->rq_arg.tail[0] = head->arg.tail[0];
 548         rqstp->rq_arg.len = head->arg.len;
 549         rqstp->rq_arg.buflen = head->arg.buflen;
 550
 551         /* Free the context */
 552         svc_rdma_put_context(head, 0);
 553
 554         /* XXX: What should this be? */
 555         rqstp->rq_prot = IPPROTO_MAX;
 556         svc_xprt_copy_addrs(rqstp, rqstp->rq_xprt);
 557
 558         ret = rqstp->rq_arg.head[0].iov_len
 559                 + rqstp->rq_arg.page_len
 560                 + rqstp->rq_arg.tail[0].iov_len;
 561         dprintk("svcrdma: deferred read ret=%d, rq_arg.len=%u, "
 562                 "rq_arg.head[0].iov_base=%p, rq_arg.head[0].iov_len=%zu\n",
 563                 ret, rqstp->rq_arg.len, rqstp->rq_arg.head[0].iov_base,
 564                 rqstp->rq_arg.head[0].iov_len);
 565
 566         return ret;
 567 }
 568
 569 /*
 570  * Set up the rqstp thread context to point to the RQ buffer. If
 571  * necessary, pull additional data from the client with an RDMA_READ
 572  * request.
 573  */
 574 int svc_rdma_recvfrom(struct svc_rqst *rqstp)
 575 {
 576         struct svc_xprt *xprt = rqstp->rq_xprt;
 577         struct svcxprt_rdma *rdma_xprt =
 578                 container_of(xprt, struct svcxprt_rdma, sc_xprt);
 579         struct svc_rdma_op_ctxt *ctxt = NULL;
 580         struct rpcrdma_msg *rmsgp;
 581         int ret = 0;
 582         int len;
 583
 584         dprintk("svcrdma: rqstp=%p\n", rqstp);
 585
 586         spin_lock_bh(&rdma_xprt->sc_rq_dto_lock);
 587         if (!list_empty(&rdma_xprt->sc_read_complete_q)) {
 588                 ctxt = list_entry(rdma_xprt->sc_read_complete_q.next,
 589                                   struct svc_rdma_op_ctxt,
 590                                   dto_q);
 591                 list_del_init(&ctxt->dto_q);
 592                 spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);
 593                 return rdma_read_complete(rqstp, ctxt);
 594         } else if (!list_empty(&rdma_xprt->sc_rq_dto_q)) {
 595                 ctxt = list_entry(rdma_xprt->sc_rq_dto_q.next,
 596                                   struct svc_rdma_op_ctxt,
 597                                   dto_q);
 598                 list_del_init(&ctxt->dto_q);
 599         } else {
 600                 atomic_inc(&rdma_stat_rq_starve);
 601                 clear_bit(XPT_DATA, &xprt->xpt_flags);
 602                 ctxt = NULL;
 603         }
 604         spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);
 605         if (!ctxt) {
 606                 /* This is the EAGAIN path. The svc_recv routine will
 607                  * return -EAGAIN, the nfsd thread will go to call into
 608                  * svc_recv again and we shouldn't be on the active
 609                  * transport list
 610                  */
 611                 if (test_bit(XPT_CLOSE, &xprt->xpt_flags))
 612                         goto close_out;
 613
 614                 goto out;
 615         }
 616         dprintk("svcrdma: processing ctxt=%p on xprt=%p, rqstp=%p, status=%d\n",
 617                 ctxt, rdma_xprt, rqstp, ctxt->wc_status);
 618         atomic_inc(&rdma_stat_recv);
 619
 620         /* Build up the XDR from the receive buffers. */
 621         rdma_build_arg_xdr(rqstp, ctxt, ctxt->byte_len);
 622
 623         /* Decode the RDMA header. */
 624         len = svc_rdma_xdr_decode_req(&rmsgp, rqstp);
 625         rqstp->rq_xprt_hlen = len;
 626
 627         /* If the request is invalid, reply with an error */
 628         if (len < 0) {
 629                 if (len == -ENOSYS)
 630                         svc_rdma_send_error(rdma_xprt, rmsgp, ERR_VERS);
 631                 goto close_out;
 632         }
 633
 634         /* Read read-list data. */
 635         ret = rdma_read_chunks(rdma_xprt, rmsgp, rqstp, ctxt);
 636         if (ret > 0) {
 637                 /* read-list posted, defer until data received from client. */
 638                 goto defer;
 639         } else if (ret < 0) {
 640                 /* Post of read-list failed, free context. */
 641                 svc_rdma_put_context(ctxt, 1);
 642                 return 0;
 643         }
 644
 645         ret = rqstp->rq_arg.head[0].iov_len
 646                 + rqstp->rq_arg.page_len
 647                 + rqstp->rq_arg.tail[0].iov_len;
 648         svc_rdma_put_context(ctxt, 0);
 649  out:
 650         dprintk("svcrdma: ret=%d, rq_arg.len=%u, "
 651                 "rq_arg.head[0].iov_base=%p, rq_arg.head[0].iov_len=%zd\n",
 652                 ret, rqstp->rq_arg.len,
 653                 rqstp->rq_arg.head[0].iov_base,
 654                 rqstp->rq_arg.head[0].iov_len);
 655         rqstp->rq_prot = IPPROTO_MAX;
 656         svc_xprt_copy_addrs(rqstp, xprt);
 657         return ret;
 658
 659  close_out:
 660         if (ctxt)
 661                 svc_rdma_put_context(ctxt, 1);
 662         dprintk("svcrdma: transport %p is closing\n", xprt);
 663         /*
 664          * Set the close bit and enqueue it. svc_recv will see the
 665          * close bit and call svc_xprt_delete
 666          */
 667         set_bit(XPT_CLOSE, &xprt->xpt_flags);
 668 defer:
 669         return 0;
 670 }