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 page *page;
  63         u32 bc;
  64         int sge_no;
  65
  66         /* Swap the page in the SGE with the page in argpages */
  67         page = ctxt->pages[0];
  68         put_page(rqstp->rq_pages[0]);
  69         rqstp->rq_pages[0] = page;
  70
  71         /* Set up the XDR head */
  72         rqstp->rq_arg.head[0].iov_base = page_address(page);
  73         rqstp->rq_arg.head[0].iov_len =
  74                 min_t(size_t, byte_count, ctxt->sge[0].length);
  75         rqstp->rq_arg.len = byte_count;
  76         rqstp->rq_arg.buflen = byte_count;
  77
  78         /* Compute bytes past head in the SGL */
  79         bc = byte_count - rqstp->rq_arg.head[0].iov_len;
  80
  81         /* If data remains, store it in the pagelist */
  82         rqstp->rq_arg.page_len = bc;
  83         rqstp->rq_arg.page_base = 0;
  84         rqstp->rq_arg.pages = &rqstp->rq_pages[1];
  85         sge_no = 1;
  86         while (bc && sge_no < ctxt->count) {
  87                 page = ctxt->pages[sge_no];
  88                 put_page(rqstp->rq_pages[sge_no]);
  89                 rqstp->rq_pages[sge_no] = page;
  90                 bc -= min_t(u32, bc, ctxt->sge[sge_no].length);
  91                 rqstp->rq_arg.buflen += ctxt->sge[sge_no].length;
  92                 sge_no++;
  93         }
  94         rqstp->rq_respages = &rqstp->rq_pages[sge_no];
  95         rqstp->rq_next_page = rqstp->rq_respages + 1;
  96
  97         /* We should never run out of SGE because the limit is defined to
  98          * support the max allowed RPC data length
  99          */
 100         BUG_ON(bc && (sge_no == ctxt->count));
 101         BUG_ON((rqstp->rq_arg.head[0].iov_len + rqstp->rq_arg.page_len)
 102                != byte_count);
 103         BUG_ON(rqstp->rq_arg.len != byte_count);
 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 static int rdma_read_max_sge(struct svcxprt_rdma *xprt, int sge_count)
 119 {
 120         if (rdma_node_get_transport(xprt->sc_cm_id->device->node_type) ==
 121              RDMA_TRANSPORT_IWARP)
 122                 return 1;
 123         else
 124                 return min_t(int, sge_count, xprt->sc_max_sge);
 125 }
 126
 127 typedef int (*rdma_reader_fn)(struct svcxprt_rdma *xprt,
 128                               struct svc_rqst *rqstp,
 129                               struct svc_rdma_op_ctxt *head,
 130                               int *page_no,
 131                               u32 *page_offset,
 132                               u32 rs_handle,
 133                               u32 rs_length,
 134                               u64 rs_offset,
 135                               int last);
 136
 137 /* Issue an RDMA_READ using the local lkey to map the data sink */
 138 static int rdma_read_chunk_lcl(struct svcxprt_rdma *xprt,
 139                                struct svc_rqst *rqstp,
 140                                struct svc_rdma_op_ctxt *head,
 141                                int *page_no,
 142                                u32 *page_offset,
 143                                u32 rs_handle,
 144                                u32 rs_length,
 145                                u64 rs_offset,
 146                                int last)
 147 {
 148         struct ib_send_wr read_wr;
 149         int pages_needed = PAGE_ALIGN(*page_offset + rs_length) >> PAGE_SHIFT;
 150         struct svc_rdma_op_ctxt *ctxt = svc_rdma_get_context(xprt);
 151         int ret, read, pno;
 152         u32 pg_off = *page_offset;
 153         u32 pg_no = *page_no;
 154
 155         ctxt->direction = DMA_FROM_DEVICE;
 156         ctxt->read_hdr = head;
 157         pages_needed =
 158                 min_t(int, pages_needed, rdma_read_max_sge(xprt, pages_needed));
 159         read = min_t(int, pages_needed << PAGE_SHIFT, rs_length);
 160
 161         for (pno = 0; pno < pages_needed; pno++) {
 162                 int len = min_t(int, rs_length, PAGE_SIZE - pg_off);
 163
 164                 head->arg.pages[pg_no] = rqstp->rq_arg.pages[pg_no];
 165                 head->arg.page_len += len;
 166                 head->arg.len += len;
 167                 if (!pg_off)
 168                         head->count++;
 169                 rqstp->rq_respages = &rqstp->rq_arg.pages[pg_no+1];
 170                 rqstp->rq_next_page = rqstp->rq_respages + 1;
 171                 ctxt->sge[pno].addr =
 172                         ib_dma_map_page(xprt->sc_cm_id->device,
 173                                         head->arg.pages[pg_no], pg_off,
 174                                         PAGE_SIZE - pg_off,
 175                                         DMA_FROM_DEVICE);
 176                 ret = ib_dma_mapping_error(xprt->sc_cm_id->device,
 177                                            ctxt->sge[pno].addr);
 178                 if (ret)
 179                         goto err;
 180                 atomic_inc(&xprt->sc_dma_used);
 181
 182                 /* The lkey here is either a local dma lkey or a dma_mr lkey */
 183                 ctxt->sge[pno].lkey = xprt->sc_dma_lkey;
 184                 ctxt->sge[pno].length = len;
 185                 ctxt->count++;
 186
 187                 /* adjust offset and wrap to next page if needed */
 188                 pg_off += len;
 189                 if (pg_off == PAGE_SIZE) {
 190                         pg_off = 0;
 191                         pg_no++;
 192                 }
 193                 rs_length -= len;
 194         }
 195
 196         if (last && rs_length == 0)
 197                 set_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 198         else
 199                 clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 200
 201         memset(&read_wr, 0, sizeof(read_wr));
 202         read_wr.wr_id = (unsigned long)ctxt;
 203         read_wr.opcode = IB_WR_RDMA_READ;
 204         ctxt->wr_op = read_wr.opcode;
 205         read_wr.send_flags = IB_SEND_SIGNALED;
 206         read_wr.wr.rdma.rkey = rs_handle;
 207         read_wr.wr.rdma.remote_addr = rs_offset;
 208         read_wr.sg_list = ctxt->sge;
 209         read_wr.num_sge = pages_needed;
 210
 211         ret = svc_rdma_send(xprt, &read_wr);
 212         if (ret) {
 213                 pr_err("svcrdma: Error %d posting RDMA_READ\n", ret);
 214                 set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
 215                 goto err;
 216         }
 217
 218         /* return current location in page array */
 219         *page_no = pg_no;
 220         *page_offset = pg_off;
 221         ret = read;
 222         atomic_inc(&rdma_stat_read);
 223         return ret;
 224  err:
 225         svc_rdma_unmap_dma(ctxt);
 226         svc_rdma_put_context(ctxt, 0);
 227         return ret;
 228 }
 229
 230 /* Issue an RDMA_READ using an FRMR to map the data sink */
 231 static int rdma_read_chunk_frmr(struct svcxprt_rdma *xprt,
 232                                 struct svc_rqst *rqstp,
 233                                 struct svc_rdma_op_ctxt *head,
 234                                 int *page_no,
 235                                 u32 *page_offset,
 236                                 u32 rs_handle,
 237                                 u32 rs_length,
 238                                 u64 rs_offset,
 239                                 int last)
 240 {
 241         struct ib_send_wr read_wr;
 242         struct ib_send_wr inv_wr;
 243         struct ib_send_wr fastreg_wr;
 244         u8 key;
 245         int pages_needed = PAGE_ALIGN(*page_offset + rs_length) >> PAGE_SHIFT;
 246         struct svc_rdma_op_ctxt *ctxt = svc_rdma_get_context(xprt);
 247         struct svc_rdma_fastreg_mr *frmr = svc_rdma_get_frmr(xprt);
 248         int ret, read, pno;
 249         u32 pg_off = *page_offset;
 250         u32 pg_no = *page_no;
 251
 252         if (IS_ERR(frmr))
 253                 return -ENOMEM;
 254
 255         ctxt->direction = DMA_FROM_DEVICE;
 256         ctxt->frmr = frmr;
 257         pages_needed = min_t(int, pages_needed, xprt->sc_frmr_pg_list_len);
 258         read = min_t(int, pages_needed << PAGE_SHIFT, rs_length);
 259
 260         frmr->kva = page_address(rqstp->rq_arg.pages[pg_no]);
 261         frmr->direction = DMA_FROM_DEVICE;
 262         frmr->access_flags = (IB_ACCESS_LOCAL_WRITE|IB_ACCESS_REMOTE_WRITE);
 263         frmr->map_len = pages_needed << PAGE_SHIFT;
 264         frmr->page_list_len = pages_needed;
 265
 266         for (pno = 0; pno < pages_needed; pno++) {
 267                 int len = min_t(int, rs_length, PAGE_SIZE - pg_off);
 268
 269                 head->arg.pages[pg_no] = rqstp->rq_arg.pages[pg_no];
 270                 head->arg.page_len += len;
 271                 head->arg.len += len;
 272                 if (!pg_off)
 273                         head->count++;
 274                 rqstp->rq_respages = &rqstp->rq_arg.pages[pg_no+1];
 275                 rqstp->rq_next_page = rqstp->rq_respages + 1;
 276                 frmr->page_list->page_list[pno] =
 277                         ib_dma_map_page(xprt->sc_cm_id->device,
 278                                         head->arg.pages[pg_no], 0,
 279                                         PAGE_SIZE, DMA_FROM_DEVICE);
 280                 ret = ib_dma_mapping_error(xprt->sc_cm_id->device,
 281                                            frmr->page_list->page_list[pno]);
 282                 if (ret)
 283                         goto err;
 284                 atomic_inc(&xprt->sc_dma_used);
 285
 286                 /* adjust offset and wrap to next page if needed */
 287                 pg_off += len;
 288                 if (pg_off == PAGE_SIZE) {
 289                         pg_off = 0;
 290                         pg_no++;
 291                 }
 292                 rs_length -= len;
 293         }
 294
 295         if (last && rs_length == 0)
 296                 set_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 297         else
 298                 clear_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags);
 299
 300         /* Bump the key */
 301         key = (u8)(frmr->mr->lkey & 0x000000FF);
 302         ib_update_fast_reg_key(frmr->mr, ++key);
 303
 304         ctxt->sge[0].addr = (unsigned long)frmr->kva + *page_offset;
 305         ctxt->sge[0].lkey = frmr->mr->lkey;
 306         ctxt->sge[0].length = read;
 307         ctxt->count = 1;
 308         ctxt->read_hdr = head;
 309
 310         /* Prepare FASTREG WR */
 311         memset(&fastreg_wr, 0, sizeof(fastreg_wr));
 312         fastreg_wr.opcode = IB_WR_FAST_REG_MR;
 313         fastreg_wr.send_flags = IB_SEND_SIGNALED;
 314         fastreg_wr.wr.fast_reg.iova_start = (unsigned long)frmr->kva;
 315         fastreg_wr.wr.fast_reg.page_list = frmr->page_list;
 316         fastreg_wr.wr.fast_reg.page_list_len = frmr->page_list_len;
 317         fastreg_wr.wr.fast_reg.page_shift = PAGE_SHIFT;
 318         fastreg_wr.wr.fast_reg.length = frmr->map_len;
 319         fastreg_wr.wr.fast_reg.access_flags = frmr->access_flags;
 320         fastreg_wr.wr.fast_reg.rkey = frmr->mr->lkey;
 321         fastreg_wr.next = &read_wr;
 322
 323         /* Prepare RDMA_READ */
 324         memset(&read_wr, 0, sizeof(read_wr));
 325         read_wr.send_flags = IB_SEND_SIGNALED;
 326         read_wr.wr.rdma.rkey = rs_handle;
 327         read_wr.wr.rdma.remote_addr = rs_offset;
 328         read_wr.sg_list = ctxt->sge;
 329         read_wr.num_sge = 1;
 330         if (xprt->sc_dev_caps & SVCRDMA_DEVCAP_READ_W_INV) {
 331                 read_wr.opcode = IB_WR_RDMA_READ_WITH_INV;
 332                 read_wr.wr_id = (unsigned long)ctxt;
 333                 read_wr.ex.invalidate_rkey = ctxt->frmr->mr->lkey;
 334         } else {
 335                 read_wr.opcode = IB_WR_RDMA_READ;
 336                 read_wr.next = &inv_wr;
 337                 /* Prepare invalidate */
 338                 memset(&inv_wr, 0, sizeof(inv_wr));
 339                 inv_wr.wr_id = (unsigned long)ctxt;
 340                 inv_wr.opcode = IB_WR_LOCAL_INV;
 341                 inv_wr.send_flags = IB_SEND_SIGNALED | IB_SEND_FENCE;
 342                 inv_wr.ex.invalidate_rkey = frmr->mr->lkey;
 343         }
 344         ctxt->wr_op = read_wr.opcode;
 345
 346         /* Post the chain */
 347         ret = svc_rdma_send(xprt, &fastreg_wr);
 348         if (ret) {
 349                 pr_err("svcrdma: Error %d posting RDMA_READ\n", ret);
 350                 set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
 351                 goto err;
 352         }
 353
 354         /* return current location in page array */
 355         *page_no = pg_no;
 356         *page_offset = pg_off;
 357         ret = read;
 358         atomic_inc(&rdma_stat_read);
 359         return ret;
 360  err:
 361         svc_rdma_unmap_dma(ctxt);
 362         svc_rdma_put_context(ctxt, 0);
 363         svc_rdma_put_frmr(xprt, frmr);
 364         return ret;
 365 }
 366
 367 static int rdma_read_chunks(struct svcxprt_rdma *xprt,
 368                             struct rpcrdma_msg *rmsgp,
 369                             struct svc_rqst *rqstp,
 370                             struct svc_rdma_op_ctxt *head)
 371 {
 372         int page_no, ch_count, ret;
 373         struct rpcrdma_read_chunk *ch;
 374         u32 page_offset, byte_count;
 375         u64 rs_offset;
 376         rdma_reader_fn reader;
 377
 378         /* If no read list is present, return 0 */
 379         ch = svc_rdma_get_read_chunk(rmsgp);
 380         if (!ch)
 381                 return 0;
 382
 383         svc_rdma_rcl_chunk_counts(ch, &ch_count, &byte_count);
 384         if (ch_count > RPCSVC_MAXPAGES)
 385                 return -EINVAL;
 386
 387         /* The request is completed when the RDMA_READs complete. The
 388          * head context keeps all the pages that comprise the
 389          * request.
 390          */
 391         head->arg.head[0] = rqstp->rq_arg.head[0];
 392         head->arg.tail[0] = rqstp->rq_arg.tail[0];
 393         head->arg.pages = &head->pages[head->count];
 394         head->hdr_count = head->count;
 395         head->arg.page_base = 0;
 396         head->arg.page_len = 0;
 397         head->arg.len = rqstp->rq_arg.len;
 398         head->arg.buflen = rqstp->rq_arg.buflen;
 399
 400         /* Use FRMR if supported */
 401         if (xprt->sc_dev_caps & SVCRDMA_DEVCAP_FAST_REG)
 402                 reader = rdma_read_chunk_frmr;
 403         else
 404                 reader = rdma_read_chunk_lcl;
 405
 406         page_no = 0; page_offset = 0;
 407         for (ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];
 408              ch->rc_discrim != 0; ch++) {
 409
 410                 xdr_decode_hyper((__be32 *)&ch->rc_target.rs_offset,
 411                                  &rs_offset);
 412                 byte_count = ntohl(ch->rc_target.rs_length);
 413
 414                 while (byte_count > 0) {
 415                         ret = reader(xprt, rqstp, head,
 416                                      &page_no, &page_offset,
 417                                      ntohl(ch->rc_target.rs_handle),
 418                                      byte_count, rs_offset,
 419                                      ((ch+1)->rc_discrim == 0) /* last */
 420                                      );
 421                         if (ret < 0)
 422                                 goto err;
 423                         byte_count -= ret;
 424                         rs_offset += ret;
 425                         head->arg.buflen += ret;
 426                 }
 427         }
 428         ret = 1;
 429  err:
 430         /* Detach arg pages. svc_recv will replenish them */
 431         for (page_no = 0;
 432              &rqstp->rq_pages[page_no] < rqstp->rq_respages; page_no++)
 433                 rqstp->rq_pages[page_no] = NULL;
 434
 435         return ret;
 436 }
 437
 438 static int rdma_read_complete(struct svc_rqst *rqstp,
 439                               struct svc_rdma_op_ctxt *head)
 440 {
 441         int page_no;
 442         int ret;
 443
 444         BUG_ON(!head);
 445
 446         /* Copy RPC pages */
 447         for (page_no = 0; page_no < head->count; page_no++) {
 448                 put_page(rqstp->rq_pages[page_no]);
 449                 rqstp->rq_pages[page_no] = head->pages[page_no];
 450         }
 451         /* Point rq_arg.pages past header */
 452         rqstp->rq_arg.pages = &rqstp->rq_pages[head->hdr_count];
 453         rqstp->rq_arg.page_len = head->arg.page_len;
 454         rqstp->rq_arg.page_base = head->arg.page_base;
 455
 456         /* rq_respages starts after the last arg page */
 457         rqstp->rq_respages = &rqstp->rq_arg.pages[page_no];
 458         rqstp->rq_next_page = rqstp->rq_respages + 1;
 459
 460         /* Rebuild rq_arg head and tail. */
 461         rqstp->rq_arg.head[0] = head->arg.head[0];
 462         rqstp->rq_arg.tail[0] = head->arg.tail[0];
 463         rqstp->rq_arg.len = head->arg.len;
 464         rqstp->rq_arg.buflen = head->arg.buflen;
 465
 466         /* Free the context */
 467         svc_rdma_put_context(head, 0);
 468
 469         /* XXX: What should this be? */
 470         rqstp->rq_prot = IPPROTO_MAX;
 471         svc_xprt_copy_addrs(rqstp, rqstp->rq_xprt);
 472
 473         ret = rqstp->rq_arg.head[0].iov_len
 474                 + rqstp->rq_arg.page_len
 475                 + rqstp->rq_arg.tail[0].iov_len;
 476         dprintk("svcrdma: deferred read ret=%d, rq_arg.len =%d, "
 477                 "rq_arg.head[0].iov_base=%p, rq_arg.head[0].iov_len = %zd\n",
 478                 ret, rqstp->rq_arg.len, rqstp->rq_arg.head[0].iov_base,
 479                 rqstp->rq_arg.head[0].iov_len);
 480
 481         return ret;
 482 }
 483
 484 /*
 485  * Set up the rqstp thread context to point to the RQ buffer. If
 486  * necessary, pull additional data from the client with an RDMA_READ
 487  * request.
 488  */
 489 int svc_rdma_recvfrom(struct svc_rqst *rqstp)
 490 {
 491         struct svc_xprt *xprt = rqstp->rq_xprt;
 492         struct svcxprt_rdma *rdma_xprt =
 493                 container_of(xprt, struct svcxprt_rdma, sc_xprt);
 494         struct svc_rdma_op_ctxt *ctxt = NULL;
 495         struct rpcrdma_msg *rmsgp;
 496         int ret = 0;
 497         int len;
 498
 499         dprintk("svcrdma: rqstp=%p\n", rqstp);
 500
 501         spin_lock_bh(&rdma_xprt->sc_rq_dto_lock);
 502         if (!list_empty(&rdma_xprt->sc_read_complete_q)) {
 503                 ctxt = list_entry(rdma_xprt->sc_read_complete_q.next,
 504                                   struct svc_rdma_op_ctxt,
 505                                   dto_q);
 506                 list_del_init(&ctxt->dto_q);
 507                 spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);
 508                 return rdma_read_complete(rqstp, ctxt);
 509         } else if (!list_empty(&rdma_xprt->sc_rq_dto_q)) {
 510                 ctxt = list_entry(rdma_xprt->sc_rq_dto_q.next,
 511                                   struct svc_rdma_op_ctxt,
 512                                   dto_q);
 513                 list_del_init(&ctxt->dto_q);
 514         } else {
 515                 atomic_inc(&rdma_stat_rq_starve);
 516                 clear_bit(XPT_DATA, &xprt->xpt_flags);
 517                 ctxt = NULL;
 518         }
 519         spin_unlock_bh(&rdma_xprt->sc_rq_dto_lock);
 520         if (!ctxt) {
 521                 /* This is the EAGAIN path. The svc_recv routine will
 522                  * return -EAGAIN, the nfsd thread will go to call into
 523                  * svc_recv again and we shouldn't be on the active
 524                  * transport list
 525                  */
 526                 if (test_bit(XPT_CLOSE, &xprt->xpt_flags))
 527                         goto close_out;
 528
 529                 goto out;
 530         }
 531         dprintk("svcrdma: processing ctxt=%p on xprt=%p, rqstp=%p, status=%d\n",
 532                 ctxt, rdma_xprt, rqstp, ctxt->wc_status);
 533         BUG_ON(ctxt->wc_status != IB_WC_SUCCESS);
 534         atomic_inc(&rdma_stat_recv);
 535
 536         /* Build up the XDR from the receive buffers. */
 537         rdma_build_arg_xdr(rqstp, ctxt, ctxt->byte_len);
 538
 539         /* Decode the RDMA header. */
 540         len = svc_rdma_xdr_decode_req(&rmsgp, rqstp);
 541         rqstp->rq_xprt_hlen = len;
 542
 543         /* If the request is invalid, reply with an error */
 544         if (len < 0) {
 545                 if (len == -ENOSYS)
 546                         svc_rdma_send_error(rdma_xprt, rmsgp, ERR_VERS);
 547                 goto close_out;
 548         }
 549
 550         /* Read read-list data. */
 551         ret = rdma_read_chunks(rdma_xprt, rmsgp, rqstp, ctxt);
 552         if (ret > 0) {
 553                 /* read-list posted, defer until data received from client. */
 554                 goto defer;
 555         } else if (ret < 0) {
 556                 /* Post of read-list failed, free context. */
 557                 svc_rdma_put_context(ctxt, 1);
 558                 return 0;
 559         }
 560
 561         ret = rqstp->rq_arg.head[0].iov_len
 562                 + rqstp->rq_arg.page_len
 563                 + rqstp->rq_arg.tail[0].iov_len;
 564         svc_rdma_put_context(ctxt, 0);
 565  out:
 566         dprintk("svcrdma: ret = %d, rq_arg.len =%d, "
 567                 "rq_arg.head[0].iov_base=%p, rq_arg.head[0].iov_len = %zd\n",
 568                 ret, rqstp->rq_arg.len,
 569                 rqstp->rq_arg.head[0].iov_base,
 570                 rqstp->rq_arg.head[0].iov_len);
 571         rqstp->rq_prot = IPPROTO_MAX;
 572         svc_xprt_copy_addrs(rqstp, xprt);
 573         return ret;
 574
 575  close_out:
 576         if (ctxt)
 577                 svc_rdma_put_context(ctxt, 1);
 578         dprintk("svcrdma: transport %p is closing\n", xprt);
 579         /*
 580          * Set the close bit and enqueue it. svc_recv will see the
 581          * close bit and call svc_xprt_delete
 582          */
 583         set_bit(XPT_CLOSE, &xprt->xpt_flags);
 584 defer:
 585         return 0;
 586 }