1 // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause 2 /* 3 * Copyright (c) 2016-2018 Oracle. All rights reserved. 4 * Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved. 5 * Copyright (c) 2005-2006 Network Appliance, Inc. All rights reserved. 6 * 7 * This software is available to you under a choice of one of two 8 * licenses. You may choose to be licensed under the terms of the GNU 9 * General Public License (GPL) Version 2, available from the file 10 * COPYING in the main directory of this source tree, or the BSD-type 11 * license below: 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 17 * Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 20 * Redistributions in binary form must reproduce the above 21 * copyright notice, this list of conditions and the following 22 * disclaimer in the documentation and/or other materials provided 23 * with the distribution. 24 * 25 * Neither the name of the Network Appliance, Inc. nor the names of 26 * its contributors may be used to endorse or promote products 27 * derived from this software without specific prior written 28 * permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 31 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 32 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 33 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 34 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 36 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 37 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 38 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 39 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 40 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 41 * 42 * Author: Tom Tucker <tom@opengridcomputing.com> 43 */ 44 45 /* Operation 46 * 47 * The main entry point is svc_rdma_sendto. This is called by the 48 * RPC server when an RPC Reply is ready to be transmitted to a client. 49 * 50 * The passed-in svc_rqst contains a struct xdr_buf which holds an 51 * XDR-encoded RPC Reply message. sendto must construct the RPC-over-RDMA 52 * transport header, post all Write WRs needed for this Reply, then post 53 * a Send WR conveying the transport header and the RPC message itself to 54 * the client. 55 * 56 * svc_rdma_sendto must fully transmit the Reply before returning, as 57 * the svc_rqst will be recycled as soon as sendto returns. Remaining 58 * resources referred to by the svc_rqst are also recycled at that time. 59 * Therefore any resources that must remain longer must be detached 60 * from the svc_rqst and released later. 61 * 62 * Page Management 63 * 64 * The I/O that performs Reply transmission is asynchronous, and may 65 * complete well after sendto returns. Thus pages under I/O must be 66 * removed from the svc_rqst before sendto returns. 67 * 68 * The logic here depends on Send Queue and completion ordering. Since 69 * the Send WR is always posted last, it will always complete last. Thus 70 * when it completes, it is guaranteed that all previous Write WRs have 71 * also completed. 72 * 73 * Write WRs are constructed and posted. Each Write segment gets its own 74 * svc_rdma_rw_ctxt, allowing the Write completion handler to find and 75 * DMA-unmap the pages under I/O for that Write segment. The Write 76 * completion handler does not release any pages. 77 * 78 * When the Send WR is constructed, it also gets its own svc_rdma_send_ctxt. 79 * The ownership of all of the Reply's pages are transferred into that 80 * ctxt, the Send WR is posted, and sendto returns. 81 * 82 * The svc_rdma_send_ctxt is presented when the Send WR completes. The 83 * Send completion handler finally releases the Reply's pages. 84 * 85 * This mechanism also assumes that completions on the transport's Send 86 * Completion Queue do not run in parallel. Otherwise a Write completion 87 * and Send completion running at the same time could release pages that 88 * are still DMA-mapped. 89 * 90 * Error Handling 91 * 92 * - If the Send WR is posted successfully, it will either complete 93 * successfully, or get flushed. Either way, the Send completion 94 * handler releases the Reply's pages. 95 * - If the Send WR cannot be not posted, the forward path releases 96 * the Reply's pages. 97 * 98 * This handles the case, without the use of page reference counting, 99 * where two different Write segments send portions of the same page. 100 */ 101 102 #include <linux/spinlock.h> 103 #include <asm/unaligned.h> 104 105 #include <rdma/ib_verbs.h> 106 #include <rdma/rdma_cm.h> 107 108 #include <linux/sunrpc/debug.h> 109 #include <linux/sunrpc/rpc_rdma.h> 110 #include <linux/sunrpc/svc_rdma.h> 111 112 #include "xprt_rdma.h" 113 #include <trace/events/rpcrdma.h> 114 115 #define RPCDBG_FACILITY RPCDBG_SVCXPRT 116 117 static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc); 118 119 static inline struct svc_rdma_send_ctxt * 120 svc_rdma_next_send_ctxt(struct list_head *list) 121 { 122 return list_first_entry_or_null(list, struct svc_rdma_send_ctxt, 123 sc_list); 124 } 125 126 static struct svc_rdma_send_ctxt * 127 svc_rdma_send_ctxt_alloc(struct svcxprt_rdma *rdma) 128 { 129 struct svc_rdma_send_ctxt *ctxt; 130 dma_addr_t addr; 131 void *buffer; 132 size_t size; 133 int i; 134 135 size = sizeof(*ctxt); 136 size += rdma->sc_max_send_sges * sizeof(struct ib_sge); 137 ctxt = kmalloc(size, GFP_KERNEL); 138 if (!ctxt) 139 goto fail0; 140 buffer = kmalloc(rdma->sc_max_req_size, GFP_KERNEL); 141 if (!buffer) 142 goto fail1; 143 addr = ib_dma_map_single(rdma->sc_pd->device, buffer, 144 rdma->sc_max_req_size, DMA_TO_DEVICE); 145 if (ib_dma_mapping_error(rdma->sc_pd->device, addr)) 146 goto fail2; 147 148 ctxt->sc_send_wr.next = NULL; 149 ctxt->sc_send_wr.wr_cqe = &ctxt->sc_cqe; 150 ctxt->sc_send_wr.sg_list = ctxt->sc_sges; 151 ctxt->sc_send_wr.send_flags = IB_SEND_SIGNALED; 152 ctxt->sc_cqe.done = svc_rdma_wc_send; 153 ctxt->sc_xprt_buf = buffer; 154 ctxt->sc_sges[0].addr = addr; 155 156 for (i = 0; i < rdma->sc_max_send_sges; i++) 157 ctxt->sc_sges[i].lkey = rdma->sc_pd->local_dma_lkey; 158 return ctxt; 159 160 fail2: 161 kfree(buffer); 162 fail1: 163 kfree(ctxt); 164 fail0: 165 return NULL; 166 } 167 168 /** 169 * svc_rdma_send_ctxts_destroy - Release all send_ctxt's for an xprt 170 * @rdma: svcxprt_rdma being torn down 171 * 172 */ 173 void svc_rdma_send_ctxts_destroy(struct svcxprt_rdma *rdma) 174 { 175 struct svc_rdma_send_ctxt *ctxt; 176 177 while ((ctxt = svc_rdma_next_send_ctxt(&rdma->sc_send_ctxts))) { 178 list_del(&ctxt->sc_list); 179 ib_dma_unmap_single(rdma->sc_pd->device, 180 ctxt->sc_sges[0].addr, 181 rdma->sc_max_req_size, 182 DMA_TO_DEVICE); 183 kfree(ctxt->sc_xprt_buf); 184 kfree(ctxt); 185 } 186 } 187 188 /** 189 * svc_rdma_send_ctxt_get - Get a free send_ctxt 190 * @rdma: controlling svcxprt_rdma 191 * 192 * Returns a ready-to-use send_ctxt, or NULL if none are 193 * available and a fresh one cannot be allocated. 194 */ 195 struct svc_rdma_send_ctxt *svc_rdma_send_ctxt_get(struct svcxprt_rdma *rdma) 196 { 197 struct svc_rdma_send_ctxt *ctxt; 198 199 spin_lock(&rdma->sc_send_lock); 200 ctxt = svc_rdma_next_send_ctxt(&rdma->sc_send_ctxts); 201 if (!ctxt) 202 goto out_empty; 203 list_del(&ctxt->sc_list); 204 spin_unlock(&rdma->sc_send_lock); 205 206 out: 207 ctxt->sc_send_wr.num_sge = 0; 208 ctxt->sc_cur_sge_no = 0; 209 ctxt->sc_page_count = 0; 210 return ctxt; 211 212 out_empty: 213 spin_unlock(&rdma->sc_send_lock); 214 ctxt = svc_rdma_send_ctxt_alloc(rdma); 215 if (!ctxt) 216 return NULL; 217 goto out; 218 } 219 220 /** 221 * svc_rdma_send_ctxt_put - Return send_ctxt to free list 222 * @rdma: controlling svcxprt_rdma 223 * @ctxt: object to return to the free list 224 * 225 * Pages left in sc_pages are DMA unmapped and released. 226 */ 227 void svc_rdma_send_ctxt_put(struct svcxprt_rdma *rdma, 228 struct svc_rdma_send_ctxt *ctxt) 229 { 230 struct ib_device *device = rdma->sc_cm_id->device; 231 unsigned int i; 232 233 /* The first SGE contains the transport header, which 234 * remains mapped until @ctxt is destroyed. 235 */ 236 for (i = 1; i < ctxt->sc_send_wr.num_sge; i++) 237 ib_dma_unmap_page(device, 238 ctxt->sc_sges[i].addr, 239 ctxt->sc_sges[i].length, 240 DMA_TO_DEVICE); 241 242 for (i = 0; i < ctxt->sc_page_count; ++i) 243 put_page(ctxt->sc_pages[i]); 244 245 spin_lock(&rdma->sc_send_lock); 246 list_add(&ctxt->sc_list, &rdma->sc_send_ctxts); 247 spin_unlock(&rdma->sc_send_lock); 248 } 249 250 /** 251 * svc_rdma_wc_send - Invoked by RDMA provider for each polled Send WC 252 * @cq: Completion Queue context 253 * @wc: Work Completion object 254 * 255 * NB: The svc_xprt/svcxprt_rdma is pinned whenever it's possible that 256 * the Send completion handler could be running. 257 */ 258 static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc) 259 { 260 struct svcxprt_rdma *rdma = cq->cq_context; 261 struct ib_cqe *cqe = wc->wr_cqe; 262 struct svc_rdma_send_ctxt *ctxt; 263 264 trace_svcrdma_wc_send(wc); 265 266 atomic_inc(&rdma->sc_sq_avail); 267 wake_up(&rdma->sc_send_wait); 268 269 ctxt = container_of(cqe, struct svc_rdma_send_ctxt, sc_cqe); 270 svc_rdma_send_ctxt_put(rdma, ctxt); 271 272 if (unlikely(wc->status != IB_WC_SUCCESS)) { 273 set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); 274 svc_xprt_enqueue(&rdma->sc_xprt); 275 } 276 277 svc_xprt_put(&rdma->sc_xprt); 278 } 279 280 /** 281 * svc_rdma_send - Post a single Send WR 282 * @rdma: transport on which to post the WR 283 * @wr: prepared Send WR to post 284 * 285 * Returns zero the Send WR was posted successfully. Otherwise, a 286 * negative errno is returned. 287 */ 288 int svc_rdma_send(struct svcxprt_rdma *rdma, struct ib_send_wr *wr) 289 { 290 int ret; 291 292 might_sleep(); 293 294 /* If the SQ is full, wait until an SQ entry is available */ 295 while (1) { 296 if ((atomic_dec_return(&rdma->sc_sq_avail) < 0)) { 297 atomic_inc(&rdma_stat_sq_starve); 298 trace_svcrdma_sq_full(rdma); 299 atomic_inc(&rdma->sc_sq_avail); 300 wait_event(rdma->sc_send_wait, 301 atomic_read(&rdma->sc_sq_avail) > 1); 302 if (test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags)) 303 return -ENOTCONN; 304 trace_svcrdma_sq_retry(rdma); 305 continue; 306 } 307 308 svc_xprt_get(&rdma->sc_xprt); 309 ret = ib_post_send(rdma->sc_qp, wr, NULL); 310 trace_svcrdma_post_send(wr, ret); 311 if (ret) { 312 set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); 313 svc_xprt_put(&rdma->sc_xprt); 314 wake_up(&rdma->sc_send_wait); 315 } 316 break; 317 } 318 return ret; 319 } 320 321 static u32 xdr_padsize(u32 len) 322 { 323 return (len & 3) ? (4 - (len & 3)) : 0; 324 } 325 326 /* Returns length of transport header, in bytes. 327 */ 328 static unsigned int svc_rdma_reply_hdr_len(__be32 *rdma_resp) 329 { 330 unsigned int nsegs; 331 __be32 *p; 332 333 p = rdma_resp; 334 335 /* RPC-over-RDMA V1 replies never have a Read list. */ 336 p += rpcrdma_fixed_maxsz + 1; 337 338 /* Skip Write list. */ 339 while (*p++ != xdr_zero) { 340 nsegs = be32_to_cpup(p++); 341 p += nsegs * rpcrdma_segment_maxsz; 342 } 343 344 /* Skip Reply chunk. */ 345 if (*p++ != xdr_zero) { 346 nsegs = be32_to_cpup(p++); 347 p += nsegs * rpcrdma_segment_maxsz; 348 } 349 350 return (unsigned long)p - (unsigned long)rdma_resp; 351 } 352 353 /* One Write chunk is copied from Call transport header to Reply 354 * transport header. Each segment's length field is updated to 355 * reflect number of bytes consumed in the segment. 356 * 357 * Returns number of segments in this chunk. 358 */ 359 static unsigned int xdr_encode_write_chunk(__be32 *dst, __be32 *src, 360 unsigned int remaining) 361 { 362 unsigned int i, nsegs; 363 u32 seg_len; 364 365 /* Write list discriminator */ 366 *dst++ = *src++; 367 368 /* number of segments in this chunk */ 369 nsegs = be32_to_cpup(src); 370 *dst++ = *src++; 371 372 for (i = nsegs; i; i--) { 373 /* segment's RDMA handle */ 374 *dst++ = *src++; 375 376 /* bytes returned in this segment */ 377 seg_len = be32_to_cpu(*src); 378 if (remaining >= seg_len) { 379 /* entire segment was consumed */ 380 *dst = *src; 381 remaining -= seg_len; 382 } else { 383 /* segment only partly filled */ 384 *dst = cpu_to_be32(remaining); 385 remaining = 0; 386 } 387 dst++; src++; 388 389 /* segment's RDMA offset */ 390 *dst++ = *src++; 391 *dst++ = *src++; 392 } 393 394 return nsegs; 395 } 396 397 /* The client provided a Write list in the Call message. Fill in 398 * the segments in the first Write chunk in the Reply's transport 399 * header with the number of bytes consumed in each segment. 400 * Remaining chunks are returned unused. 401 * 402 * Assumptions: 403 * - Client has provided only one Write chunk 404 */ 405 static void svc_rdma_xdr_encode_write_list(__be32 *rdma_resp, __be32 *wr_ch, 406 unsigned int consumed) 407 { 408 unsigned int nsegs; 409 __be32 *p, *q; 410 411 /* RPC-over-RDMA V1 replies never have a Read list. */ 412 p = rdma_resp + rpcrdma_fixed_maxsz + 1; 413 414 q = wr_ch; 415 while (*q != xdr_zero) { 416 nsegs = xdr_encode_write_chunk(p, q, consumed); 417 q += 2 + nsegs * rpcrdma_segment_maxsz; 418 p += 2 + nsegs * rpcrdma_segment_maxsz; 419 consumed = 0; 420 } 421 422 /* Terminate Write list */ 423 *p++ = xdr_zero; 424 425 /* Reply chunk discriminator; may be replaced later */ 426 *p = xdr_zero; 427 } 428 429 /* The client provided a Reply chunk in the Call message. Fill in 430 * the segments in the Reply chunk in the Reply message with the 431 * number of bytes consumed in each segment. 432 * 433 * Assumptions: 434 * - Reply can always fit in the provided Reply chunk 435 */ 436 static void svc_rdma_xdr_encode_reply_chunk(__be32 *rdma_resp, __be32 *rp_ch, 437 unsigned int consumed) 438 { 439 __be32 *p; 440 441 /* Find the Reply chunk in the Reply's xprt header. 442 * RPC-over-RDMA V1 replies never have a Read list. 443 */ 444 p = rdma_resp + rpcrdma_fixed_maxsz + 1; 445 446 /* Skip past Write list */ 447 while (*p++ != xdr_zero) 448 p += 1 + be32_to_cpup(p) * rpcrdma_segment_maxsz; 449 450 xdr_encode_write_chunk(p, rp_ch, consumed); 451 } 452 453 /* Parse the RPC Call's transport header. 454 */ 455 static void svc_rdma_get_write_arrays(__be32 *rdma_argp, 456 __be32 **write, __be32 **reply) 457 { 458 __be32 *p; 459 460 p = rdma_argp + rpcrdma_fixed_maxsz; 461 462 /* Read list */ 463 while (*p++ != xdr_zero) 464 p += 5; 465 466 /* Write list */ 467 if (*p != xdr_zero) { 468 *write = p; 469 while (*p++ != xdr_zero) 470 p += 1 + be32_to_cpu(*p) * 4; 471 } else { 472 *write = NULL; 473 p++; 474 } 475 476 /* Reply chunk */ 477 if (*p != xdr_zero) 478 *reply = p; 479 else 480 *reply = NULL; 481 } 482 483 static int svc_rdma_dma_map_page(struct svcxprt_rdma *rdma, 484 struct svc_rdma_send_ctxt *ctxt, 485 struct page *page, 486 unsigned long offset, 487 unsigned int len) 488 { 489 struct ib_device *dev = rdma->sc_cm_id->device; 490 dma_addr_t dma_addr; 491 492 dma_addr = ib_dma_map_page(dev, page, offset, len, DMA_TO_DEVICE); 493 if (ib_dma_mapping_error(dev, dma_addr)) 494 goto out_maperr; 495 496 ctxt->sc_sges[ctxt->sc_cur_sge_no].addr = dma_addr; 497 ctxt->sc_sges[ctxt->sc_cur_sge_no].length = len; 498 ctxt->sc_send_wr.num_sge++; 499 return 0; 500 501 out_maperr: 502 trace_svcrdma_dma_map_page(rdma, page); 503 return -EIO; 504 } 505 506 /* ib_dma_map_page() is used here because svc_rdma_dma_unmap() 507 * handles DMA-unmap and it uses ib_dma_unmap_page() exclusively. 508 */ 509 static int svc_rdma_dma_map_buf(struct svcxprt_rdma *rdma, 510 struct svc_rdma_send_ctxt *ctxt, 511 unsigned char *base, 512 unsigned int len) 513 { 514 return svc_rdma_dma_map_page(rdma, ctxt, virt_to_page(base), 515 offset_in_page(base), len); 516 } 517 518 /** 519 * svc_rdma_sync_reply_hdr - DMA sync the transport header buffer 520 * @rdma: controlling transport 521 * @ctxt: send_ctxt for the Send WR 522 * @len: length of transport header 523 * 524 */ 525 void svc_rdma_sync_reply_hdr(struct svcxprt_rdma *rdma, 526 struct svc_rdma_send_ctxt *ctxt, 527 unsigned int len) 528 { 529 ctxt->sc_sges[0].length = len; 530 ctxt->sc_send_wr.num_sge++; 531 ib_dma_sync_single_for_device(rdma->sc_pd->device, 532 ctxt->sc_sges[0].addr, len, 533 DMA_TO_DEVICE); 534 } 535 536 /* If the xdr_buf has more elements than the device can 537 * transmit in a single RDMA Send, then the reply will 538 * have to be copied into a bounce buffer. 539 */ 540 static bool svc_rdma_pull_up_needed(struct svcxprt_rdma *rdma, 541 struct xdr_buf *xdr, 542 __be32 *wr_lst) 543 { 544 int elements; 545 546 /* xdr->head */ 547 elements = 1; 548 549 /* xdr->pages */ 550 if (!wr_lst) { 551 unsigned int remaining; 552 unsigned long pageoff; 553 554 pageoff = xdr->page_base & ~PAGE_MASK; 555 remaining = xdr->page_len; 556 while (remaining) { 557 ++elements; 558 remaining -= min_t(u32, PAGE_SIZE - pageoff, 559 remaining); 560 pageoff = 0; 561 } 562 } 563 564 /* xdr->tail */ 565 if (xdr->tail[0].iov_len) 566 ++elements; 567 568 /* assume 1 SGE is needed for the transport header */ 569 return elements >= rdma->sc_max_send_sges; 570 } 571 572 /* The device is not capable of sending the reply directly. 573 * Assemble the elements of @xdr into the transport header 574 * buffer. 575 */ 576 static int svc_rdma_pull_up_reply_msg(struct svcxprt_rdma *rdma, 577 struct svc_rdma_send_ctxt *ctxt, 578 struct xdr_buf *xdr, __be32 *wr_lst) 579 { 580 unsigned char *dst, *tailbase; 581 unsigned int taillen; 582 583 dst = ctxt->sc_xprt_buf; 584 dst += ctxt->sc_sges[0].length; 585 586 memcpy(dst, xdr->head[0].iov_base, xdr->head[0].iov_len); 587 dst += xdr->head[0].iov_len; 588 589 tailbase = xdr->tail[0].iov_base; 590 taillen = xdr->tail[0].iov_len; 591 if (wr_lst) { 592 u32 xdrpad; 593 594 xdrpad = xdr_padsize(xdr->page_len); 595 if (taillen && xdrpad) { 596 tailbase += xdrpad; 597 taillen -= xdrpad; 598 } 599 } else { 600 unsigned int len, remaining; 601 unsigned long pageoff; 602 struct page **ppages; 603 604 ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT); 605 pageoff = xdr->page_base & ~PAGE_MASK; 606 remaining = xdr->page_len; 607 while (remaining) { 608 len = min_t(u32, PAGE_SIZE - pageoff, remaining); 609 610 memcpy(dst, page_address(*ppages), len); 611 remaining -= len; 612 dst += len; 613 pageoff = 0; 614 } 615 } 616 617 if (taillen) 618 memcpy(dst, tailbase, taillen); 619 620 ctxt->sc_sges[0].length += xdr->len; 621 ib_dma_sync_single_for_device(rdma->sc_pd->device, 622 ctxt->sc_sges[0].addr, 623 ctxt->sc_sges[0].length, 624 DMA_TO_DEVICE); 625 626 return 0; 627 } 628 629 /* svc_rdma_map_reply_msg - Map the buffer holding RPC message 630 * @rdma: controlling transport 631 * @ctxt: send_ctxt for the Send WR 632 * @xdr: prepared xdr_buf containing RPC message 633 * @wr_lst: pointer to Call header's Write list, or NULL 634 * 635 * Load the xdr_buf into the ctxt's sge array, and DMA map each 636 * element as it is added. 637 * 638 * Returns zero on success, or a negative errno on failure. 639 */ 640 int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma, 641 struct svc_rdma_send_ctxt *ctxt, 642 struct xdr_buf *xdr, __be32 *wr_lst) 643 { 644 unsigned int len, remaining; 645 unsigned long page_off; 646 struct page **ppages; 647 unsigned char *base; 648 u32 xdr_pad; 649 int ret; 650 651 if (svc_rdma_pull_up_needed(rdma, xdr, wr_lst)) 652 return svc_rdma_pull_up_reply_msg(rdma, ctxt, xdr, wr_lst); 653 654 ++ctxt->sc_cur_sge_no; 655 ret = svc_rdma_dma_map_buf(rdma, ctxt, 656 xdr->head[0].iov_base, 657 xdr->head[0].iov_len); 658 if (ret < 0) 659 return ret; 660 661 /* If a Write chunk is present, the xdr_buf's page list 662 * is not included inline. However the Upper Layer may 663 * have added XDR padding in the tail buffer, and that 664 * should not be included inline. 665 */ 666 if (wr_lst) { 667 base = xdr->tail[0].iov_base; 668 len = xdr->tail[0].iov_len; 669 xdr_pad = xdr_padsize(xdr->page_len); 670 671 if (len && xdr_pad) { 672 base += xdr_pad; 673 len -= xdr_pad; 674 } 675 676 goto tail; 677 } 678 679 ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT); 680 page_off = xdr->page_base & ~PAGE_MASK; 681 remaining = xdr->page_len; 682 while (remaining) { 683 len = min_t(u32, PAGE_SIZE - page_off, remaining); 684 685 ++ctxt->sc_cur_sge_no; 686 ret = svc_rdma_dma_map_page(rdma, ctxt, *ppages++, 687 page_off, len); 688 if (ret < 0) 689 return ret; 690 691 remaining -= len; 692 page_off = 0; 693 } 694 695 base = xdr->tail[0].iov_base; 696 len = xdr->tail[0].iov_len; 697 tail: 698 if (len) { 699 ++ctxt->sc_cur_sge_no; 700 ret = svc_rdma_dma_map_buf(rdma, ctxt, base, len); 701 if (ret < 0) 702 return ret; 703 } 704 705 return 0; 706 } 707 708 /* The svc_rqst and all resources it owns are released as soon as 709 * svc_rdma_sendto returns. Transfer pages under I/O to the ctxt 710 * so they are released by the Send completion handler. 711 */ 712 static void svc_rdma_save_io_pages(struct svc_rqst *rqstp, 713 struct svc_rdma_send_ctxt *ctxt) 714 { 715 int i, pages = rqstp->rq_next_page - rqstp->rq_respages; 716 717 ctxt->sc_page_count += pages; 718 for (i = 0; i < pages; i++) { 719 ctxt->sc_pages[i] = rqstp->rq_respages[i]; 720 rqstp->rq_respages[i] = NULL; 721 } 722 723 /* Prevent svc_xprt_release from releasing pages in rq_pages */ 724 rqstp->rq_next_page = rqstp->rq_respages; 725 } 726 727 /* Prepare the portion of the RPC Reply that will be transmitted 728 * via RDMA Send. The RPC-over-RDMA transport header is prepared 729 * in sc_sges[0], and the RPC xdr_buf is prepared in following sges. 730 * 731 * Depending on whether a Write list or Reply chunk is present, 732 * the server may send all, a portion of, or none of the xdr_buf. 733 * In the latter case, only the transport header (sc_sges[0]) is 734 * transmitted. 735 * 736 * RDMA Send is the last step of transmitting an RPC reply. Pages 737 * involved in the earlier RDMA Writes are here transferred out 738 * of the rqstp and into the sctxt's page array. These pages are 739 * DMA unmapped by each Write completion, but the subsequent Send 740 * completion finally releases these pages. 741 * 742 * Assumptions: 743 * - The Reply's transport header will never be larger than a page. 744 */ 745 static int svc_rdma_send_reply_msg(struct svcxprt_rdma *rdma, 746 struct svc_rdma_send_ctxt *sctxt, 747 struct svc_rdma_recv_ctxt *rctxt, 748 struct svc_rqst *rqstp, 749 __be32 *wr_lst, __be32 *rp_ch) 750 { 751 int ret; 752 753 if (!rp_ch) { 754 ret = svc_rdma_map_reply_msg(rdma, sctxt, 755 &rqstp->rq_res, wr_lst); 756 if (ret < 0) 757 return ret; 758 } 759 760 svc_rdma_save_io_pages(rqstp, sctxt); 761 762 if (rctxt->rc_inv_rkey) { 763 sctxt->sc_send_wr.opcode = IB_WR_SEND_WITH_INV; 764 sctxt->sc_send_wr.ex.invalidate_rkey = rctxt->rc_inv_rkey; 765 } else { 766 sctxt->sc_send_wr.opcode = IB_WR_SEND; 767 } 768 dprintk("svcrdma: posting Send WR with %u sge(s)\n", 769 sctxt->sc_send_wr.num_sge); 770 return svc_rdma_send(rdma, &sctxt->sc_send_wr); 771 } 772 773 /* Given the client-provided Write and Reply chunks, the server was not 774 * able to form a complete reply. Return an RDMA_ERROR message so the 775 * client can retire this RPC transaction. As above, the Send completion 776 * routine releases payload pages that were part of a previous RDMA Write. 777 * 778 * Remote Invalidation is skipped for simplicity. 779 */ 780 static int svc_rdma_send_error_msg(struct svcxprt_rdma *rdma, 781 struct svc_rdma_send_ctxt *ctxt, 782 struct svc_rqst *rqstp) 783 { 784 __be32 *p; 785 int ret; 786 787 p = ctxt->sc_xprt_buf; 788 trace_svcrdma_err_chunk(*p); 789 p += 3; 790 *p++ = rdma_error; 791 *p = err_chunk; 792 svc_rdma_sync_reply_hdr(rdma, ctxt, RPCRDMA_HDRLEN_ERR); 793 794 svc_rdma_save_io_pages(rqstp, ctxt); 795 796 ctxt->sc_send_wr.opcode = IB_WR_SEND; 797 ret = svc_rdma_send(rdma, &ctxt->sc_send_wr); 798 if (ret) { 799 svc_rdma_send_ctxt_put(rdma, ctxt); 800 return ret; 801 } 802 803 return 0; 804 } 805 806 /** 807 * svc_rdma_sendto - Transmit an RPC reply 808 * @rqstp: processed RPC request, reply XDR already in ::rq_res 809 * 810 * Any resources still associated with @rqstp are released upon return. 811 * If no reply message was possible, the connection is closed. 812 * 813 * Returns: 814 * %0 if an RPC reply has been successfully posted, 815 * %-ENOMEM if a resource shortage occurred (connection is lost), 816 * %-ENOTCONN if posting failed (connection is lost). 817 */ 818 int svc_rdma_sendto(struct svc_rqst *rqstp) 819 { 820 struct svc_xprt *xprt = rqstp->rq_xprt; 821 struct svcxprt_rdma *rdma = 822 container_of(xprt, struct svcxprt_rdma, sc_xprt); 823 struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt; 824 __be32 *p, *rdma_argp, *rdma_resp, *wr_lst, *rp_ch; 825 struct xdr_buf *xdr = &rqstp->rq_res; 826 struct svc_rdma_send_ctxt *sctxt; 827 int ret; 828 829 rdma_argp = rctxt->rc_recv_buf; 830 svc_rdma_get_write_arrays(rdma_argp, &wr_lst, &rp_ch); 831 832 /* Create the RDMA response header. xprt->xpt_mutex, 833 * acquired in svc_send(), serializes RPC replies. The 834 * code path below that inserts the credit grant value 835 * into each transport header runs only inside this 836 * critical section. 837 */ 838 ret = -ENOMEM; 839 sctxt = svc_rdma_send_ctxt_get(rdma); 840 if (!sctxt) 841 goto err0; 842 rdma_resp = sctxt->sc_xprt_buf; 843 844 p = rdma_resp; 845 *p++ = *rdma_argp; 846 *p++ = *(rdma_argp + 1); 847 *p++ = rdma->sc_fc_credits; 848 *p++ = rp_ch ? rdma_nomsg : rdma_msg; 849 850 /* Start with empty chunks */ 851 *p++ = xdr_zero; 852 *p++ = xdr_zero; 853 *p = xdr_zero; 854 855 if (wr_lst) { 856 /* XXX: Presume the client sent only one Write chunk */ 857 ret = svc_rdma_send_write_chunk(rdma, wr_lst, xdr); 858 if (ret < 0) 859 goto err2; 860 svc_rdma_xdr_encode_write_list(rdma_resp, wr_lst, ret); 861 } 862 if (rp_ch) { 863 ret = svc_rdma_send_reply_chunk(rdma, rp_ch, wr_lst, xdr); 864 if (ret < 0) 865 goto err2; 866 svc_rdma_xdr_encode_reply_chunk(rdma_resp, rp_ch, ret); 867 } 868 869 svc_rdma_sync_reply_hdr(rdma, sctxt, svc_rdma_reply_hdr_len(rdma_resp)); 870 ret = svc_rdma_send_reply_msg(rdma, sctxt, rctxt, rqstp, 871 wr_lst, rp_ch); 872 if (ret < 0) 873 goto err1; 874 ret = 0; 875 876 out: 877 rqstp->rq_xprt_ctxt = NULL; 878 svc_rdma_recv_ctxt_put(rdma, rctxt); 879 return ret; 880 881 err2: 882 if (ret != -E2BIG && ret != -EINVAL) 883 goto err1; 884 885 ret = svc_rdma_send_error_msg(rdma, sctxt, rqstp); 886 if (ret < 0) 887 goto err1; 888 ret = 0; 889 goto out; 890 891 err1: 892 svc_rdma_send_ctxt_put(rdma, sctxt); 893 err0: 894 trace_svcrdma_send_failed(rqstp, ret); 895 set_bit(XPT_CLOSE, &xprt->xpt_flags); 896 ret = -ENOTCONN; 897 goto out; 898 } 899