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_send_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_id = (unsigned long)ctxt;
 183         read_wr.opcode = IB_WR_RDMA_READ;
 184         ctxt->wr_op = read_wr.opcode;
 185         read_wr.send_flags = IB_SEND_SIGNALED;
 186         read_wr.wr.rdma.rkey = rs_handle;
 187         read_wr.wr.rdma.remote_addr = rs_offset;
 188         read_wr.sg_list = ctxt->sge;
 189         read_wr.num_sge = pages_needed;
 190
 191         ret = svc_rdma_send(xprt, &read_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_send_wr read_wr;
 222         struct ib_send_wr inv_wr;
 223         struct ib_send_wr fastreg_wr;
 224         u8 key;
 225         int pages_needed = 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;
 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         pages_needed = min_t(int, pages_needed, xprt->sc_frmr_pg_list_len);
 238         read = min_t(int, pages_needed << PAGE_SHIFT, rs_length);
 239
 240         frmr->kva = page_address(rqstp->rq_arg.pages[pg_no]);
 241         frmr->direction = DMA_FROM_DEVICE;
 242         frmr->access_flags = (IB_ACCESS_LOCAL_WRITE|IB_ACCESS_REMOTE_WRITE);
 243         frmr->map_len = pages_needed << PAGE_SHIFT;
 244         frmr->page_list_len = pages_needed;
 245
 246         for (pno = 0; pno < pages_needed; pno++) {
 247                 int len = min_t(int, rs_length, PAGE_SIZE - pg_off);
 248
 249                 head->arg.pages[pg_no] = rqstp->rq_arg.pages[pg_no];
 250                 head->arg.page_len += len;
 251                 head->arg.len += len;
 252                 if (!pg_off)
 253                         head->count++;
 254                 rqstp->rq_respages = &rqstp->rq_arg.pages[pg_no+1];
 255                 rqstp->rq_next_page = rqstp->rq_respages + 1;
 256                 frmr->page_list->page_list[pno] =
 257                         ib_dma_map_page(xprt->sc_cm_id->device,
 258                                         head->arg.pages[pg_no], 0,
 259                                         PAGE_SIZE, DMA_FROM_DEVICE);
 260                 ret = ib_dma_mapping_error(xprt->sc_cm_id->device,
 261                                            frmr->page_list->page_list[pno]);
 262                 if (ret)
 263                         goto err;
 264                 atomic_inc(&xprt->sc_dma_used);
 265
 266                 /* adjust offset and wrap to next page if needed */
 267                 pg_off += len;
 268                 if (pg_off == PAGE_SIZE) {
 269                         pg_off = 0;
 270                         pg_no++;
 271                 }
 272                 rs_length -= len;
 273         }
 274
 275         if (last && rs_length == 0)
 276                 set_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 277         else
 278                 clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 279
 280         /* Bump the key */
 281         key = (u8)(frmr->mr->lkey & 0x000000FF);
 282         ib_update_fast_reg_key(frmr->mr, ++key);
 283
 284         ctxt->sge[0].addr = (unsigned long)frmr->kva + *page_offset;
 285         ctxt->sge[0].lkey = frmr->mr->lkey;
 286         ctxt->sge[0].length = read;
 287         ctxt->count = 1;
 288         ctxt->read_hdr = head;
 289
 290         /* Prepare FASTREG WR */
 291         memset(&fastreg_wr, 0, sizeof(fastreg_wr));
 292         fastreg_wr.opcode = IB_WR_FAST_REG_MR;
 293         fastreg_wr.send_flags = IB_SEND_SIGNALED;
 294         fastreg_wr.wr.fast_reg.iova_start = (unsigned long)frmr->kva;
 295         fastreg_wr.wr.fast_reg.page_list = frmr->page_list;
 296         fastreg_wr.wr.fast_reg.page_list_len = frmr->page_list_len;
 297         fastreg_wr.wr.fast_reg.page_shift = PAGE_SHIFT;
 298         fastreg_wr.wr.fast_reg.length = frmr->map_len;
 299         fastreg_wr.wr.fast_reg.access_flags = frmr->access_flags;
 300         fastreg_wr.wr.fast_reg.rkey = frmr->mr->lkey;
 301         fastreg_wr.next = &read_wr;
 302
 303         /* Prepare RDMA_READ */
 304         memset(&read_wr, 0, sizeof(read_wr));
 305         read_wr.send_flags = IB_SEND_SIGNALED;
 306         read_wr.wr.rdma.rkey = rs_handle;
 307         read_wr.wr.rdma.remote_addr = rs_offset;
 308         read_wr.sg_list = ctxt->sge;
 309         read_wr.num_sge = 1;
 310         if (xprt->sc_dev_caps & SVCRDMA_DEVCAP_READ_W_INV) {
 311                 read_wr.opcode = IB_WR_RDMA_READ_WITH_INV;
 312                 read_wr.wr_id = (unsigned long)ctxt;
 313                 read_wr.ex.invalidate_rkey = ctxt->frmr->mr->lkey;
 314         } else {
 315                 read_wr.opcode = IB_WR_RDMA_READ;
 316                 read_wr.next = &inv_wr;
 317                 /* Prepare invalidate */
 318                 memset(&inv_wr, 0, sizeof(inv_wr));
 319                 inv_wr.wr_id = (unsigned long)ctxt;
 320                 inv_wr.opcode = IB_WR_LOCAL_INV;
 321                 inv_wr.send_flags = IB_SEND_SIGNALED | IB_SEND_FENCE;
 322                 inv_wr.ex.invalidate_rkey = frmr->mr->lkey;
 323         }
 324         ctxt->wr_op = read_wr.opcode;
 325
 326         /* Post the chain */
 327         ret = svc_rdma_send(xprt, &fastreg_wr);
 328         if (ret) {
 329                 pr_err("svcrdma: Error %d posting RDMA_READ\n", ret);
 330                 set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
 331                 goto err;
 332         }
 333
 334         /* return current location in page array */
 335         *page_no = pg_no;
 336         *page_offset = pg_off;
 337         ret = read;
 338         atomic_inc(&rdma_stat_read);
 339         return ret;
 340  err:
 341         svc_rdma_unmap_dma(ctxt);
 342         svc_rdma_put_context(ctxt, 0);
 343         svc_rdma_put_frmr(xprt, frmr);
 344         return ret;
 345 }
 346
 347 static unsigned int
 348 rdma_rcl_chunk_count(struct rpcrdma_read_chunk *ch)
 349 {
 350         unsigned int count;
 351
 352         for (count = 0; ch->rc_discrim != xdr_zero; ch++)
 353                 count++;
 354         return count;
 355 }
 356
 357 /* If there was additional inline content, append it to the end of arg.pages.
 358  * Tail copy has to be done after the reader function has determined how many
 359  * pages are needed for RDMA READ.
 360  */
 361 static int
 362 rdma_copy_tail(struct svc_rqst *rqstp, struct svc_rdma_op_ctxt *head,
 363                u32 position, u32 byte_count, u32 page_offset, int page_no)
 364 {
 365         char *srcp, *destp;
 366         int ret;
 367
 368         ret = 0;
 369         srcp = head->arg.head[0].iov_base + position;
 370         byte_count = head->arg.head[0].iov_len - position;
 371         if (byte_count > PAGE_SIZE) {
 372                 dprintk("svcrdma: large tail unsupported\n");
 373                 return 0;
 374         }
 375
 376         /* Fit as much of the tail on the current page as possible */
 377         if (page_offset != PAGE_SIZE) {
 378                 destp = page_address(rqstp->rq_arg.pages[page_no]);
 379                 destp += page_offset;
 380                 while (byte_count--) {
 381                         *destp++ = *srcp++;
 382                         page_offset++;
 383                         if (page_offset == PAGE_SIZE && byte_count)
 384                                 goto more;
 385                 }
 386                 goto done;
 387         }
 388
 389 more:
 390         /* Fit the rest on the next page */
 391         page_no++;
 392         destp = page_address(rqstp->rq_arg.pages[page_no]);
 393         while (byte_count--)
 394                 *destp++ = *srcp++;
 395
 396         rqstp->rq_respages = &rqstp->rq_arg.pages[page_no+1];
 397         rqstp->rq_next_page = rqstp->rq_respages + 1;
 398
 399 done:
 400         byte_count = head->arg.head[0].iov_len - position;
 401         head->arg.page_len += byte_count;
 402         head->arg.len += byte_count;
 403         head->arg.buflen += byte_count;
 404         return 1;
 405 }
 406
 407 static int rdma_read_chunks(struct svcxprt_rdma *xprt,
 408                             struct rpcrdma_msg *rmsgp,
 409                             struct svc_rqst *rqstp,
 410                             struct svc_rdma_op_ctxt *head)
 411 {
 412         int page_no, ret;
 413         struct rpcrdma_read_chunk *ch;
 414         u32 handle, page_offset, byte_count;
 415         u32 position;
 416         u64 rs_offset;
 417         bool last;
 418
 419         /* If no read list is present, return 0 */
 420         ch = svc_rdma_get_read_chunk(rmsgp);
 421         if (!ch)
 422                 return 0;
 423
 424         if (rdma_rcl_chunk_count(ch) > RPCSVC_MAXPAGES)
 425                 return -EINVAL;
 426
 427         /* The request is completed when the RDMA_READs complete. The
 428          * head context keeps all the pages that comprise the
 429          * request.
 430          */
 431         head->arg.head[0] = rqstp->rq_arg.head[0];
 432         head->arg.tail[0] = rqstp->rq_arg.tail[0];
 433         head->hdr_count = head->count;
 434         head->arg.page_base = 0;
 435         head->arg.page_len = 0;
 436         head->arg.len = rqstp->rq_arg.len;
 437         head->arg.buflen = rqstp->rq_arg.buflen;
 438
 439         ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];
 440         position = be32_to_cpu(ch->rc_position);
 441
 442         /* RDMA_NOMSG: RDMA READ data should land just after RDMA RECV data */
 443         if (position == 0) {
 444                 head->arg.pages = &head->pages[0];
 445                 page_offset = head->byte_len;
 446         } else {
 447                 head->arg.pages = &head->pages[head->count];
 448                 page_offset = 0;
 449         }
 450
 451         ret = 0;
 452         page_no = 0;
 453         for (; ch->rc_discrim != xdr_zero; ch++) {
 454                 if (be32_to_cpu(ch->rc_position) != position)
 455                         goto err;
 456
 457                 handle = be32_to_cpu(ch->rc_target.rs_handle),
 458                 byte_count = be32_to_cpu(ch->rc_target.rs_length);
 459                 xdr_decode_hyper((__be32 *)&ch->rc_target.rs_offset,
 460                                  &rs_offset);
 461
 462                 while (byte_count > 0) {
 463                         last = (ch + 1)->rc_discrim == xdr_zero;
 464                         ret = xprt->sc_reader(xprt, rqstp, head,
 465                                               &page_no, &page_offset,
 466                                               handle, byte_count,
 467                                               rs_offset, last);
 468                         if (ret < 0)
 469                                 goto err;
 470                         byte_count -= ret;
 471                         rs_offset += ret;
 472                         head->arg.buflen += ret;
 473                 }
 474         }
 475
 476         /* Read list may need XDR round-up (see RFC 5666, s. 3.7) */
 477         if (page_offset & 3) {
 478                 u32 pad = 4 - (page_offset & 3);
 479
 480                 head->arg.page_len += pad;
 481                 head->arg.len += pad;
 482                 head->arg.buflen += pad;
 483                 page_offset += pad;
 484         }
 485
 486         ret = 1;
 487         if (position && position < head->arg.head[0].iov_len)
 488                 ret = rdma_copy_tail(rqstp, head, position,
 489                                      byte_count, page_offset, page_no);
 490         head->arg.head[0].iov_len = position;
 491         head->position = position;
 492
 493  err:
 494         /* Detach arg pages. svc_recv will replenish them */
 495         for (page_no = 0;
 496              &rqstp->rq_pages[page_no] < rqstp->rq_respages; page_no++)
 497                 rqstp->rq_pages[page_no] = NULL;
 498
 499         return ret;
 500 }
 501
 502 static int rdma_read_complete(struct svc_rqst *rqstp,
 503                               struct svc_rdma_op_ctxt *head)
 504 {
 505         int page_no;
 506         int ret;
 507
 508         /* Copy RPC pages */
 509         for (page_no = 0; page_no < head->count; page_no++) {
 510                 put_page(rqstp->rq_pages[page_no]);
 511                 rqstp->rq_pages[page_no] = head->pages[page_no];
 512         }
 513
 514         /* Adjustments made for RDMA_NOMSG type requests */
 515         if (head->position == 0) {
 516                 if (head->arg.len <= head->sge[0].length) {
 517                         head->arg.head[0].iov_len = head->arg.len -
 518                                                         head->byte_len;
 519                         head->arg.page_len = 0;
 520                 } else {
 521                         head->arg.head[0].iov_len = head->sge[0].length -
 522                                                                 head->byte_len;
 523                         head->arg.page_len = head->arg.len -
 524                                                 head->sge[0].length;
 525                 }
 526         }
 527
 528         /* Point rq_arg.pages past header */
 529         rqstp->rq_arg.pages = &rqstp->rq_pages[head->hdr_count];
 530         rqstp->rq_arg.page_len = head->arg.page_len;
 531         rqstp->rq_arg.page_base = head->arg.page_base;
 532
 533         /* rq_respages starts after the last arg page */
 534         rqstp->rq_respages = &rqstp->rq_arg.pages[page_no];
 535         rqstp->rq_next_page = rqstp->rq_respages + 1;
 536
 537         /* Rebuild rq_arg head and tail. */
 538         rqstp->rq_arg.head[0] = head->arg.head[0];
 539         rqstp->rq_arg.tail[0] = head->arg.tail[0];
 540         rqstp->rq_arg.len = head->arg.len;
 541         rqstp->rq_arg.buflen = head->arg.buflen;
 542
 543         /* Free the context */
 544         svc_rdma_put_context(head, 0);
 545
 546         /* XXX: What should this be? */
 547         rqstp->rq_prot = IPPROTO_MAX;
 548         svc_xprt_copy_addrs(rqstp, rqstp->rq_xprt);
 549
 550         ret = rqstp->rq_arg.head[0].iov_len
 551                 + rqstp->rq_arg.page_len
 552                 + rqstp->rq_arg.tail[0].iov_len;
 553         dprintk("svcrdma: deferred read ret=%d, rq_arg.len=%u, "
 554                 "rq_arg.head[0].iov_base=%p, rq_arg.head[0].iov_len=%zu\n",
 555                 ret, rqstp->rq_arg.len, rqstp->rq_arg.head[0].iov_base,
 556                 rqstp->rq_arg.head[0].iov_len);
 557
 558         return ret;
 559 }
 560
 561 /*
 562  * Set up the rqstp thread context to point to the RQ buffer. If
 563  * necessary, pull additional data from the client with an RDMA_READ
 564  * request.
 565  */
 566 int svc_rdma_recvfrom(struct svc_rqst *rqstp)
 567 {
 568         struct svc_xprt *xprt = rqstp->rq_xprt;
 569         struct svcxprt_rdma *rdma_xprt =
 570                 container_of(xprt, struct svcxprt_rdma, sc_xprt);
 571         struct svc_rdma_op_ctxt *ctxt = NULL;
 572         struct rpcrdma_msg *rmsgp;
 573         int ret = 0;
 574         int len;
 575
 576         dprintk("svcrdma: rqstp=%p\n", rqstp);
 577
 578         spin_lock_bh(&rdma_xprt->sc_rq_dto_lock);
 579         if (!list_empty(&rdma_xprt->sc_read_complete_q)) {
 580                 ctxt = list_entry(rdma_xprt->sc_read_complete_q.next,
 581                                   struct svc_rdma_op_ctxt,
 582                                   dto_q);
 583                 list_del_init(&ctxt->dto_q);
 584                 spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);
 585                 return rdma_read_complete(rqstp, ctxt);
 586         } else if (!list_empty(&rdma_xprt->sc_rq_dto_q)) {
 587                 ctxt = list_entry(rdma_xprt->sc_rq_dto_q.next,
 588                                   struct svc_rdma_op_ctxt,
 589                                   dto_q);
 590                 list_del_init(&ctxt->dto_q);
 591         } else {
 592                 atomic_inc(&rdma_stat_rq_starve);
 593                 clear_bit(XPT_DATA, &xprt->xpt_flags);
 594                 ctxt = NULL;
 595         }
 596         spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);
 597         if (!ctxt) {
 598                 /* This is the EAGAIN path. The svc_recv routine will
 599                  * return -EAGAIN, the nfsd thread will go to call into
 600                  * svc_recv again and we shouldn't be on the active
 601                  * transport list
 602                  */
 603                 if (test_bit(XPT_CLOSE, &xprt->xpt_flags))
 604                         goto close_out;
 605
 606                 goto out;
 607         }
 608         dprintk("svcrdma: processing ctxt=%p on xprt=%p, rqstp=%p, status=%d\n",
 609                 ctxt, rdma_xprt, rqstp, ctxt->wc_status);
 610         atomic_inc(&rdma_stat_recv);
 611
 612         /* Build up the XDR from the receive buffers. */
 613         rdma_build_arg_xdr(rqstp, ctxt, ctxt->byte_len);
 614
 615         /* Decode the RDMA header. */
 616         len = svc_rdma_xdr_decode_req(&rmsgp, rqstp);
 617         rqstp->rq_xprt_hlen = len;
 618
 619         /* If the request is invalid, reply with an error */
 620         if (len < 0) {
 621                 if (len == -ENOSYS)
 622                         svc_rdma_send_error(rdma_xprt, rmsgp, ERR_VERS);
 623                 goto close_out;
 624         }
 625
 626         /* Read read-list data. */
 627         ret = rdma_read_chunks(rdma_xprt, rmsgp, rqstp, ctxt);
 628         if (ret > 0) {
 629                 /* read-list posted, defer until data received from client. */
 630                 goto defer;
 631         } else if (ret < 0) {
 632                 /* Post of read-list failed, free context. */
 633                 svc_rdma_put_context(ctxt, 1);
 634                 return 0;
 635         }
 636
 637         ret = rqstp->rq_arg.head[0].iov_len
 638                 + rqstp->rq_arg.page_len
 639                 + rqstp->rq_arg.tail[0].iov_len;
 640         svc_rdma_put_context(ctxt, 0);
 641  out:
 642         dprintk("svcrdma: ret=%d, rq_arg.len=%u, "
 643                 "rq_arg.head[0].iov_base=%p, rq_arg.head[0].iov_len=%zd\n",
 644                 ret, rqstp->rq_arg.len,
 645                 rqstp->rq_arg.head[0].iov_base,
 646                 rqstp->rq_arg.head[0].iov_len);
 647         rqstp->rq_prot = IPPROTO_MAX;
 648         svc_xprt_copy_addrs(rqstp, xprt);
 649         return ret;
 650
 651  close_out:
 652         if (ctxt)
 653                 svc_rdma_put_context(ctxt, 1);
 654         dprintk("svcrdma: transport %p is closing\n", xprt);
 655         /*
 656          * Set the close bit and enqueue it. svc_recv will see the
 657          * close bit and call svc_xprt_delete
 658          */
 659         set_bit(XPT_CLOSE, &xprt->xpt_flags);
 660 defer:
 661         return 0;
 662 }