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/svc_rdma.h> 110 111#include "xprt_rdma.h" 112#include <trace/events/rpcrdma.h> 113 114#define RPCDBG_FACILITY RPCDBG_SVCXPRT 115 116static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc); 117 118static inline struct svc_rdma_send_ctxt * 119svc_rdma_next_send_ctxt(struct list_head *list) 120{ 121 return list_first_entry_or_null(list, struct svc_rdma_send_ctxt, 122 sc_list); 123} 124 125static void svc_rdma_send_cid_init(struct svcxprt_rdma *rdma, 126 struct rpc_rdma_cid *cid) 127{ 128 cid->ci_queue_id = rdma->sc_sq_cq->res.id; 129 cid->ci_completion_id = atomic_inc_return(&rdma->sc_completion_ids); 130} 131 132static struct svc_rdma_send_ctxt * 133svc_rdma_send_ctxt_alloc(struct svcxprt_rdma *rdma) 134{ 135 struct svc_rdma_send_ctxt *ctxt; 136 dma_addr_t addr; 137 void *buffer; 138 size_t size; 139 int i; 140 141 size = sizeof(*ctxt); 142 size += rdma->sc_max_send_sges * sizeof(struct ib_sge); 143 ctxt = kmalloc(size, GFP_KERNEL); 144 if (!ctxt) 145 goto fail0; 146 buffer = kmalloc(rdma->sc_max_req_size, GFP_KERNEL); 147 if (!buffer) 148 goto fail1; 149 addr = ib_dma_map_single(rdma->sc_pd->device, buffer, 150 rdma->sc_max_req_size, DMA_TO_DEVICE); 151 if (ib_dma_mapping_error(rdma->sc_pd->device, addr)) 152 goto fail2; 153 154 svc_rdma_send_cid_init(rdma, &ctxt->sc_cid); 155 156 ctxt->sc_send_wr.next = NULL; 157 ctxt->sc_send_wr.wr_cqe = &ctxt->sc_cqe; 158 ctxt->sc_send_wr.sg_list = ctxt->sc_sges; 159 ctxt->sc_send_wr.send_flags = IB_SEND_SIGNALED; 160 ctxt->sc_cqe.done = svc_rdma_wc_send; 161 ctxt->sc_xprt_buf = buffer; 162 xdr_buf_init(&ctxt->sc_hdrbuf, ctxt->sc_xprt_buf, 163 rdma->sc_max_req_size); 164 ctxt->sc_sges[0].addr = addr; 165 166 for (i = 0; i < rdma->sc_max_send_sges; i++) 167 ctxt->sc_sges[i].lkey = rdma->sc_pd->local_dma_lkey; 168 return ctxt; 169 170fail2: 171 kfree(buffer); 172fail1: 173 kfree(ctxt); 174fail0: 175 return NULL; 176} 177 178/** 179 * svc_rdma_send_ctxts_destroy - Release all send_ctxt's for an xprt 180 * @rdma: svcxprt_rdma being torn down 181 * 182 */ 183void svc_rdma_send_ctxts_destroy(struct svcxprt_rdma *rdma) 184{ 185 struct svc_rdma_send_ctxt *ctxt; 186 187 while ((ctxt = svc_rdma_next_send_ctxt(&rdma->sc_send_ctxts))) { 188 list_del(&ctxt->sc_list); 189 ib_dma_unmap_single(rdma->sc_pd->device, 190 ctxt->sc_sges[0].addr, 191 rdma->sc_max_req_size, 192 DMA_TO_DEVICE); 193 kfree(ctxt->sc_xprt_buf); 194 kfree(ctxt); 195 } 196} 197 198/** 199 * svc_rdma_send_ctxt_get - Get a free send_ctxt 200 * @rdma: controlling svcxprt_rdma 201 * 202 * Returns a ready-to-use send_ctxt, or NULL if none are 203 * available and a fresh one cannot be allocated. 204 */ 205struct svc_rdma_send_ctxt *svc_rdma_send_ctxt_get(struct svcxprt_rdma *rdma) 206{ 207 struct svc_rdma_send_ctxt *ctxt; 208 209 spin_lock(&rdma->sc_send_lock); 210 ctxt = svc_rdma_next_send_ctxt(&rdma->sc_send_ctxts); 211 if (!ctxt) 212 goto out_empty; 213 list_del(&ctxt->sc_list); 214 spin_unlock(&rdma->sc_send_lock); 215 216out: 217 rpcrdma_set_xdrlen(&ctxt->sc_hdrbuf, 0); 218 xdr_init_encode(&ctxt->sc_stream, &ctxt->sc_hdrbuf, 219 ctxt->sc_xprt_buf, NULL); 220 221 ctxt->sc_send_wr.num_sge = 0; 222 ctxt->sc_cur_sge_no = 0; 223 ctxt->sc_page_count = 0; 224 return ctxt; 225 226out_empty: 227 spin_unlock(&rdma->sc_send_lock); 228 ctxt = svc_rdma_send_ctxt_alloc(rdma); 229 if (!ctxt) 230 return NULL; 231 goto out; 232} 233 234/** 235 * svc_rdma_send_ctxt_put - Return send_ctxt to free list 236 * @rdma: controlling svcxprt_rdma 237 * @ctxt: object to return to the free list 238 * 239 * Pages left in sc_pages are DMA unmapped and released. 240 */ 241void svc_rdma_send_ctxt_put(struct svcxprt_rdma *rdma, 242 struct svc_rdma_send_ctxt *ctxt) 243{ 244 struct ib_device *device = rdma->sc_cm_id->device; 245 unsigned int i; 246 247 /* The first SGE contains the transport header, which 248 * remains mapped until @ctxt is destroyed. 249 */ 250 for (i = 1; i < ctxt->sc_send_wr.num_sge; i++) { 251 ib_dma_unmap_page(device, 252 ctxt->sc_sges[i].addr, 253 ctxt->sc_sges[i].length, 254 DMA_TO_DEVICE); 255 trace_svcrdma_dma_unmap_page(rdma, 256 ctxt->sc_sges[i].addr, 257 ctxt->sc_sges[i].length); 258 } 259 260 for (i = 0; i < ctxt->sc_page_count; ++i) 261 put_page(ctxt->sc_pages[i]); 262 263 spin_lock(&rdma->sc_send_lock); 264 list_add(&ctxt->sc_list, &rdma->sc_send_ctxts); 265 spin_unlock(&rdma->sc_send_lock); 266} 267 268/** 269 * svc_rdma_wc_send - Invoked by RDMA provider for each polled Send WC 270 * @cq: Completion Queue context 271 * @wc: Work Completion object 272 * 273 * NB: The svc_xprt/svcxprt_rdma is pinned whenever it's possible that 274 * the Send completion handler could be running. 275 */ 276static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc) 277{ 278 struct svcxprt_rdma *rdma = cq->cq_context; 279 struct ib_cqe *cqe = wc->wr_cqe; 280 struct svc_rdma_send_ctxt *ctxt = 281 container_of(cqe, struct svc_rdma_send_ctxt, sc_cqe); 282 283 trace_svcrdma_wc_send(wc, &ctxt->sc_cid); 284 285 atomic_inc(&rdma->sc_sq_avail); 286 wake_up(&rdma->sc_send_wait); 287 288 svc_rdma_send_ctxt_put(rdma, ctxt); 289 290 if (unlikely(wc->status != IB_WC_SUCCESS)) { 291 set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); 292 svc_xprt_enqueue(&rdma->sc_xprt); 293 } 294} 295 296/** 297 * svc_rdma_send - Post a single Send WR 298 * @rdma: transport on which to post the WR 299 * @ctxt: send ctxt with a Send WR ready to post 300 * 301 * Returns zero the Send WR was posted successfully. Otherwise, a 302 * negative errno is returned. 303 */ 304int svc_rdma_send(struct svcxprt_rdma *rdma, struct svc_rdma_send_ctxt *ctxt) 305{ 306 struct ib_send_wr *wr = &ctxt->sc_send_wr; 307 int ret; 308 309 might_sleep(); 310 311 /* Sync the transport header buffer */ 312 ib_dma_sync_single_for_device(rdma->sc_pd->device, 313 wr->sg_list[0].addr, 314 wr->sg_list[0].length, 315 DMA_TO_DEVICE); 316 317 /* If the SQ is full, wait until an SQ entry is available */ 318 while (1) { 319 if ((atomic_dec_return(&rdma->sc_sq_avail) < 0)) { 320 atomic_inc(&rdma_stat_sq_starve); 321 trace_svcrdma_sq_full(rdma); 322 atomic_inc(&rdma->sc_sq_avail); 323 wait_event(rdma->sc_send_wait, 324 atomic_read(&rdma->sc_sq_avail) > 1); 325 if (test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags)) 326 return -ENOTCONN; 327 trace_svcrdma_sq_retry(rdma); 328 continue; 329 } 330 331 trace_svcrdma_post_send(ctxt); 332 ret = ib_post_send(rdma->sc_qp, wr, NULL); 333 if (ret) 334 break; 335 return 0; 336 } 337 338 trace_svcrdma_sq_post_err(rdma, ret); 339 set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); 340 wake_up(&rdma->sc_send_wait); 341 return ret; 342} 343 344/** 345 * svc_rdma_encode_read_list - Encode RPC Reply's Read chunk list 346 * @sctxt: Send context for the RPC Reply 347 * 348 * Return values: 349 * On success, returns length in bytes of the Reply XDR buffer 350 * that was consumed by the Reply Read list 351 * %-EMSGSIZE on XDR buffer overflow 352 */ 353static ssize_t svc_rdma_encode_read_list(struct svc_rdma_send_ctxt *sctxt) 354{ 355 /* RPC-over-RDMA version 1 replies never have a Read list. */ 356 return xdr_stream_encode_item_absent(&sctxt->sc_stream); 357} 358 359/** 360 * svc_rdma_encode_write_segment - Encode one Write segment 361 * @src: matching Write chunk in the RPC Call header 362 * @sctxt: Send context for the RPC Reply 363 * @remaining: remaining bytes of the payload left in the Write chunk 364 * 365 * Return values: 366 * On success, returns length in bytes of the Reply XDR buffer 367 * that was consumed by the Write segment 368 * %-EMSGSIZE on XDR buffer overflow 369 */ 370static ssize_t svc_rdma_encode_write_segment(__be32 *src, 371 struct svc_rdma_send_ctxt *sctxt, 372 unsigned int *remaining) 373{ 374 __be32 *p; 375 const size_t len = rpcrdma_segment_maxsz * sizeof(*p); 376 u32 handle, length; 377 u64 offset; 378 379 p = xdr_reserve_space(&sctxt->sc_stream, len); 380 if (!p) 381 return -EMSGSIZE; 382 383 xdr_decode_rdma_segment(src, &handle, &length, &offset); 384 385 if (*remaining < length) { 386 /* segment only partly filled */ 387 length = *remaining; 388 *remaining = 0; 389 } else { 390 /* entire segment was consumed */ 391 *remaining -= length; 392 } 393 xdr_encode_rdma_segment(p, handle, length, offset); 394 395 trace_svcrdma_encode_wseg(handle, length, offset); 396 return len; 397} 398 399/** 400 * svc_rdma_encode_write_chunk - Encode one Write chunk 401 * @src: matching Write chunk in the RPC Call header 402 * @sctxt: Send context for the RPC Reply 403 * @remaining: size in bytes of the payload in the Write chunk 404 * 405 * Copy a Write chunk from the Call transport header to the 406 * Reply transport header. Update each segment's length field 407 * to reflect the number of bytes written in that segment. 408 * 409 * Return values: 410 * On success, returns length in bytes of the Reply XDR buffer 411 * that was consumed by the Write chunk 412 * %-EMSGSIZE on XDR buffer overflow 413 */ 414static ssize_t svc_rdma_encode_write_chunk(__be32 *src, 415 struct svc_rdma_send_ctxt *sctxt, 416 unsigned int remaining) 417{ 418 unsigned int i, nsegs; 419 ssize_t len, ret; 420 421 len = 0; 422 trace_svcrdma_encode_write_chunk(remaining); 423 424 src++; 425 ret = xdr_stream_encode_item_present(&sctxt->sc_stream); 426 if (ret < 0) 427 return -EMSGSIZE; 428 len += ret; 429 430 nsegs = be32_to_cpup(src++); 431 ret = xdr_stream_encode_u32(&sctxt->sc_stream, nsegs); 432 if (ret < 0) 433 return -EMSGSIZE; 434 len += ret; 435 436 for (i = nsegs; i; i--) { 437 ret = svc_rdma_encode_write_segment(src, sctxt, &remaining); 438 if (ret < 0) 439 return -EMSGSIZE; 440 src += rpcrdma_segment_maxsz; 441 len += ret; 442 } 443 444 return len; 445} 446 447/** 448 * svc_rdma_encode_write_list - Encode RPC Reply's Write chunk list 449 * @rctxt: Reply context with information about the RPC Call 450 * @sctxt: Send context for the RPC Reply 451 * @length: size in bytes of the payload in the first Write chunk 452 * 453 * The client provides a Write chunk list in the Call message. Fill 454 * in the segments in the first Write chunk in the Reply's transport 455 * header with the number of bytes consumed in each segment. 456 * Remaining chunks are returned unused. 457 * 458 * Assumptions: 459 * - Client has provided only one Write chunk 460 * 461 * Return values: 462 * On success, returns length in bytes of the Reply XDR buffer 463 * that was consumed by the Reply's Write list 464 * %-EMSGSIZE on XDR buffer overflow 465 */ 466static ssize_t 467svc_rdma_encode_write_list(const struct svc_rdma_recv_ctxt *rctxt, 468 struct svc_rdma_send_ctxt *sctxt, 469 unsigned int length) 470{ 471 ssize_t len, ret; 472 473 ret = svc_rdma_encode_write_chunk(rctxt->rc_write_list, sctxt, length); 474 if (ret < 0) 475 return ret; 476 len = ret; 477 478 /* Terminate the Write list */ 479 ret = xdr_stream_encode_item_absent(&sctxt->sc_stream); 480 if (ret < 0) 481 return ret; 482 483 return len + ret; 484} 485 486/** 487 * svc_rdma_encode_reply_chunk - Encode RPC Reply's Reply chunk 488 * @rctxt: Reply context with information about the RPC Call 489 * @sctxt: Send context for the RPC Reply 490 * @length: size in bytes of the payload in the Reply chunk 491 * 492 * Assumptions: 493 * - Reply can always fit in the client-provided Reply chunk 494 * 495 * Return values: 496 * On success, returns length in bytes of the Reply XDR buffer 497 * that was consumed by the Reply's Reply chunk 498 * %-EMSGSIZE on XDR buffer overflow 499 */ 500static ssize_t 501svc_rdma_encode_reply_chunk(const struct svc_rdma_recv_ctxt *rctxt, 502 struct svc_rdma_send_ctxt *sctxt, 503 unsigned int length) 504{ 505 return svc_rdma_encode_write_chunk(rctxt->rc_reply_chunk, sctxt, 506 length); 507} 508 509static int svc_rdma_dma_map_page(struct svcxprt_rdma *rdma, 510 struct svc_rdma_send_ctxt *ctxt, 511 struct page *page, 512 unsigned long offset, 513 unsigned int len) 514{ 515 struct ib_device *dev = rdma->sc_cm_id->device; 516 dma_addr_t dma_addr; 517 518 dma_addr = ib_dma_map_page(dev, page, offset, len, DMA_TO_DEVICE); 519 trace_svcrdma_dma_map_page(rdma, dma_addr, len); 520 if (ib_dma_mapping_error(dev, dma_addr)) 521 goto out_maperr; 522 523 ctxt->sc_sges[ctxt->sc_cur_sge_no].addr = dma_addr; 524 ctxt->sc_sges[ctxt->sc_cur_sge_no].length = len; 525 ctxt->sc_send_wr.num_sge++; 526 return 0; 527 528out_maperr: 529 return -EIO; 530} 531 532/* ib_dma_map_page() is used here because svc_rdma_dma_unmap() 533 * handles DMA-unmap and it uses ib_dma_unmap_page() exclusively. 534 */ 535static int svc_rdma_dma_map_buf(struct svcxprt_rdma *rdma, 536 struct svc_rdma_send_ctxt *ctxt, 537 unsigned char *base, 538 unsigned int len) 539{ 540 return svc_rdma_dma_map_page(rdma, ctxt, virt_to_page(base), 541 offset_in_page(base), len); 542} 543 544/** 545 * svc_rdma_pull_up_needed - Determine whether to use pull-up 546 * @rdma: controlling transport 547 * @sctxt: send_ctxt for the Send WR 548 * @rctxt: Write and Reply chunks provided by client 549 * @xdr: xdr_buf containing RPC message to transmit 550 * 551 * Returns: 552 * %true if pull-up must be used 553 * %false otherwise 554 */ 555static bool svc_rdma_pull_up_needed(struct svcxprt_rdma *rdma, 556 struct svc_rdma_send_ctxt *sctxt, 557 const struct svc_rdma_recv_ctxt *rctxt, 558 struct xdr_buf *xdr) 559{ 560 int elements; 561 562 /* For small messages, copying bytes is cheaper than DMA mapping. 563 */ 564 if (sctxt->sc_hdrbuf.len + xdr->len < RPCRDMA_PULLUP_THRESH) 565 return true; 566 567 /* Check whether the xdr_buf has more elements than can 568 * fit in a single RDMA Send. 569 */ 570 /* xdr->head */ 571 elements = 1; 572 573 /* xdr->pages */ 574 if (!rctxt || !rctxt->rc_write_list) { 575 unsigned int remaining; 576 unsigned long pageoff; 577 578 pageoff = xdr->page_base & ~PAGE_MASK; 579 remaining = xdr->page_len; 580 while (remaining) { 581 ++elements; 582 remaining -= min_t(u32, PAGE_SIZE - pageoff, 583 remaining); 584 pageoff = 0; 585 } 586 } 587 588 /* xdr->tail */ 589 if (xdr->tail[0].iov_len) 590 ++elements; 591 592 /* assume 1 SGE is needed for the transport header */ 593 return elements >= rdma->sc_max_send_sges; 594} 595 596/** 597 * svc_rdma_pull_up_reply_msg - Copy Reply into a single buffer 598 * @rdma: controlling transport 599 * @sctxt: send_ctxt for the Send WR; xprt hdr is already prepared 600 * @rctxt: Write and Reply chunks provided by client 601 * @xdr: prepared xdr_buf containing RPC message 602 * 603 * The device is not capable of sending the reply directly. 604 * Assemble the elements of @xdr into the transport header buffer. 605 * 606 * Returns zero on success, or a negative errno on failure. 607 */ 608static int svc_rdma_pull_up_reply_msg(struct svcxprt_rdma *rdma, 609 struct svc_rdma_send_ctxt *sctxt, 610 const struct svc_rdma_recv_ctxt *rctxt, 611 const struct xdr_buf *xdr) 612{ 613 unsigned char *dst, *tailbase; 614 unsigned int taillen; 615 616 dst = sctxt->sc_xprt_buf + sctxt->sc_hdrbuf.len; 617 memcpy(dst, xdr->head[0].iov_base, xdr->head[0].iov_len); 618 dst += xdr->head[0].iov_len; 619 620 tailbase = xdr->tail[0].iov_base; 621 taillen = xdr->tail[0].iov_len; 622 if (rctxt && rctxt->rc_write_list) { 623 u32 xdrpad; 624 625 xdrpad = xdr_pad_size(xdr->page_len); 626 if (taillen && xdrpad) { 627 tailbase += xdrpad; 628 taillen -= xdrpad; 629 } 630 } else { 631 unsigned int len, remaining; 632 unsigned long pageoff; 633 struct page **ppages; 634 635 ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT); 636 pageoff = xdr->page_base & ~PAGE_MASK; 637 remaining = xdr->page_len; 638 while (remaining) { 639 len = min_t(u32, PAGE_SIZE - pageoff, remaining); 640 641 memcpy(dst, page_address(*ppages) + pageoff, len); 642 remaining -= len; 643 dst += len; 644 pageoff = 0; 645 ppages++; 646 } 647 } 648 649 if (taillen) 650 memcpy(dst, tailbase, taillen); 651 652 sctxt->sc_sges[0].length += xdr->len; 653 trace_svcrdma_send_pullup(sctxt->sc_sges[0].length); 654 return 0; 655} 656 657/* svc_rdma_map_reply_msg - DMA map the buffer holding RPC message 658 * @rdma: controlling transport 659 * @sctxt: send_ctxt for the Send WR 660 * @rctxt: Write and Reply chunks provided by client 661 * @xdr: prepared xdr_buf containing RPC message 662 * 663 * Load the xdr_buf into the ctxt's sge array, and DMA map each 664 * element as it is added. The Send WR's num_sge field is set. 665 * 666 * Returns zero on success, or a negative errno on failure. 667 */ 668int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma, 669 struct svc_rdma_send_ctxt *sctxt, 670 const struct svc_rdma_recv_ctxt *rctxt, 671 struct xdr_buf *xdr) 672{ 673 unsigned int len, remaining; 674 unsigned long page_off; 675 struct page **ppages; 676 unsigned char *base; 677 u32 xdr_pad; 678 int ret; 679 680 /* Set up the (persistently-mapped) transport header SGE. */ 681 sctxt->sc_send_wr.num_sge = 1; 682 sctxt->sc_sges[0].length = sctxt->sc_hdrbuf.len; 683 684 /* If there is a Reply chunk, nothing follows the transport 685 * header, and we're done here. 686 */ 687 if (rctxt && rctxt->rc_reply_chunk) 688 return 0; 689 690 /* For pull-up, svc_rdma_send() will sync the transport header. 691 * No additional DMA mapping is necessary. 692 */ 693 if (svc_rdma_pull_up_needed(rdma, sctxt, rctxt, xdr)) 694 return svc_rdma_pull_up_reply_msg(rdma, sctxt, rctxt, xdr); 695 696 ++sctxt->sc_cur_sge_no; 697 ret = svc_rdma_dma_map_buf(rdma, sctxt, 698 xdr->head[0].iov_base, 699 xdr->head[0].iov_len); 700 if (ret < 0) 701 return ret; 702 703 /* If a Write chunk is present, the xdr_buf's page list 704 * is not included inline. However the Upper Layer may 705 * have added XDR padding in the tail buffer, and that 706 * should not be included inline. 707 */ 708 if (rctxt && rctxt->rc_write_list) { 709 base = xdr->tail[0].iov_base; 710 len = xdr->tail[0].iov_len; 711 xdr_pad = xdr_pad_size(xdr->page_len); 712 713 if (len && xdr_pad) { 714 base += xdr_pad; 715 len -= xdr_pad; 716 } 717 718 goto tail; 719 } 720 721 ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT); 722 page_off = xdr->page_base & ~PAGE_MASK; 723 remaining = xdr->page_len; 724 while (remaining) { 725 len = min_t(u32, PAGE_SIZE - page_off, remaining); 726 727 ++sctxt->sc_cur_sge_no; 728 ret = svc_rdma_dma_map_page(rdma, sctxt, *ppages++, 729 page_off, len); 730 if (ret < 0) 731 return ret; 732 733 remaining -= len; 734 page_off = 0; 735 } 736 737 base = xdr->tail[0].iov_base; 738 len = xdr->tail[0].iov_len; 739tail: 740 if (len) { 741 ++sctxt->sc_cur_sge_no; 742 ret = svc_rdma_dma_map_buf(rdma, sctxt, base, len); 743 if (ret < 0) 744 return ret; 745 } 746 747 return 0; 748} 749 750/* The svc_rqst and all resources it owns are released as soon as 751 * svc_rdma_sendto returns. Transfer pages under I/O to the ctxt 752 * so they are released by the Send completion handler. 753 */ 754static void svc_rdma_save_io_pages(struct svc_rqst *rqstp, 755 struct svc_rdma_send_ctxt *ctxt) 756{ 757 int i, pages = rqstp->rq_next_page - rqstp->rq_respages; 758 759 ctxt->sc_page_count += pages; 760 for (i = 0; i < pages; i++) { 761 ctxt->sc_pages[i] = rqstp->rq_respages[i]; 762 rqstp->rq_respages[i] = NULL; 763 } 764 765 /* Prevent svc_xprt_release from releasing pages in rq_pages */ 766 rqstp->rq_next_page = rqstp->rq_respages; 767} 768 769/* Prepare the portion of the RPC Reply that will be transmitted 770 * via RDMA Send. The RPC-over-RDMA transport header is prepared 771 * in sc_sges[0], and the RPC xdr_buf is prepared in following sges. 772 * 773 * Depending on whether a Write list or Reply chunk is present, 774 * the server may send all, a portion of, or none of the xdr_buf. 775 * In the latter case, only the transport header (sc_sges[0]) is 776 * transmitted. 777 * 778 * RDMA Send is the last step of transmitting an RPC reply. Pages 779 * involved in the earlier RDMA Writes are here transferred out 780 * of the rqstp and into the sctxt's page array. These pages are 781 * DMA unmapped by each Write completion, but the subsequent Send 782 * completion finally releases these pages. 783 * 784 * Assumptions: 785 * - The Reply's transport header will never be larger than a page. 786 */ 787static int svc_rdma_send_reply_msg(struct svcxprt_rdma *rdma, 788 struct svc_rdma_send_ctxt *sctxt, 789 const struct svc_rdma_recv_ctxt *rctxt, 790 struct svc_rqst *rqstp) 791{ 792 int ret; 793 794 ret = svc_rdma_map_reply_msg(rdma, sctxt, rctxt, &rqstp->rq_res); 795 if (ret < 0) 796 return ret; 797 798 svc_rdma_save_io_pages(rqstp, sctxt); 799 800 if (rctxt->rc_inv_rkey) { 801 sctxt->sc_send_wr.opcode = IB_WR_SEND_WITH_INV; 802 sctxt->sc_send_wr.ex.invalidate_rkey = rctxt->rc_inv_rkey; 803 } else { 804 sctxt->sc_send_wr.opcode = IB_WR_SEND; 805 } 806 return svc_rdma_send(rdma, sctxt); 807} 808 809/** 810 * svc_rdma_send_error_msg - Send an RPC/RDMA v1 error response 811 * @rdma: controlling transport context 812 * @sctxt: Send context for the response 813 * @rctxt: Receive context for incoming bad message 814 * @status: negative errno indicating error that occurred 815 * 816 * Given the client-provided Read, Write, and Reply chunks, the 817 * server was not able to parse the Call or form a complete Reply. 818 * Return an RDMA_ERROR message so the client can retire the RPC 819 * transaction. 820 * 821 * The caller does not have to release @sctxt. It is released by 822 * Send completion, or by this function on error. 823 */ 824void svc_rdma_send_error_msg(struct svcxprt_rdma *rdma, 825 struct svc_rdma_send_ctxt *sctxt, 826 struct svc_rdma_recv_ctxt *rctxt, 827 int status) 828{ 829 __be32 *rdma_argp = rctxt->rc_recv_buf; 830 __be32 *p; 831 832 rpcrdma_set_xdrlen(&sctxt->sc_hdrbuf, 0); 833 xdr_init_encode(&sctxt->sc_stream, &sctxt->sc_hdrbuf, 834 sctxt->sc_xprt_buf, NULL); 835 836 p = xdr_reserve_space(&sctxt->sc_stream, 837 rpcrdma_fixed_maxsz * sizeof(*p)); 838 if (!p) 839 goto put_ctxt; 840 841 *p++ = *rdma_argp; 842 *p++ = *(rdma_argp + 1); 843 *p++ = rdma->sc_fc_credits; 844 *p = rdma_error; 845 846 switch (status) { 847 case -EPROTONOSUPPORT: 848 p = xdr_reserve_space(&sctxt->sc_stream, 3 * sizeof(*p)); 849 if (!p) 850 goto put_ctxt; 851 852 *p++ = err_vers; 853 *p++ = rpcrdma_version; 854 *p = rpcrdma_version; 855 trace_svcrdma_err_vers(*rdma_argp); 856 break; 857 default: 858 p = xdr_reserve_space(&sctxt->sc_stream, sizeof(*p)); 859 if (!p) 860 goto put_ctxt; 861 862 *p = err_chunk; 863 trace_svcrdma_err_chunk(*rdma_argp); 864 } 865 866 /* Remote Invalidation is skipped for simplicity. */ 867 sctxt->sc_send_wr.num_sge = 1; 868 sctxt->sc_send_wr.opcode = IB_WR_SEND; 869 sctxt->sc_sges[0].length = sctxt->sc_hdrbuf.len; 870 if (svc_rdma_send(rdma, sctxt)) 871 goto put_ctxt; 872 return; 873 874put_ctxt: 875 svc_rdma_send_ctxt_put(rdma, sctxt); 876} 877 878/** 879 * svc_rdma_sendto - Transmit an RPC reply 880 * @rqstp: processed RPC request, reply XDR already in ::rq_res 881 * 882 * Any resources still associated with @rqstp are released upon return. 883 * If no reply message was possible, the connection is closed. 884 * 885 * Returns: 886 * %0 if an RPC reply has been successfully posted, 887 * %-ENOMEM if a resource shortage occurred (connection is lost), 888 * %-ENOTCONN if posting failed (connection is lost). 889 */ 890int svc_rdma_sendto(struct svc_rqst *rqstp) 891{ 892 struct svc_xprt *xprt = rqstp->rq_xprt; 893 struct svcxprt_rdma *rdma = 894 container_of(xprt, struct svcxprt_rdma, sc_xprt); 895 struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt; 896 __be32 *rdma_argp = rctxt->rc_recv_buf; 897 __be32 *wr_lst = rctxt->rc_write_list; 898 __be32 *rp_ch = rctxt->rc_reply_chunk; 899 struct xdr_buf *xdr = &rqstp->rq_res; 900 struct svc_rdma_send_ctxt *sctxt; 901 __be32 *p; 902 int ret; 903 904 ret = -ENOTCONN; 905 if (svc_xprt_is_dead(xprt)) 906 goto err0; 907 908 ret = -ENOMEM; 909 sctxt = svc_rdma_send_ctxt_get(rdma); 910 if (!sctxt) 911 goto err0; 912 913 p = xdr_reserve_space(&sctxt->sc_stream, 914 rpcrdma_fixed_maxsz * sizeof(*p)); 915 if (!p) 916 goto err0; 917 *p++ = *rdma_argp; 918 *p++ = *(rdma_argp + 1); 919 *p++ = rdma->sc_fc_credits; 920 *p = rp_ch ? rdma_nomsg : rdma_msg; 921 922 if (svc_rdma_encode_read_list(sctxt) < 0) 923 goto err0; 924 if (wr_lst) { 925 /* XXX: Presume the client sent only one Write chunk */ 926 unsigned long offset; 927 unsigned int length; 928 929 if (rctxt->rc_read_payload_length) { 930 offset = rctxt->rc_read_payload_offset; 931 length = rctxt->rc_read_payload_length; 932 } else { 933 offset = xdr->head[0].iov_len; 934 length = xdr->page_len; 935 } 936 ret = svc_rdma_send_write_chunk(rdma, wr_lst, xdr, offset, 937 length); 938 if (ret < 0) 939 goto err2; 940 if (svc_rdma_encode_write_list(rctxt, sctxt, length) < 0) 941 goto err0; 942 } else { 943 if (xdr_stream_encode_item_absent(&sctxt->sc_stream) < 0) 944 goto err0; 945 } 946 if (rp_ch) { 947 ret = svc_rdma_send_reply_chunk(rdma, rctxt, &rqstp->rq_res); 948 if (ret < 0) 949 goto err2; 950 if (svc_rdma_encode_reply_chunk(rctxt, sctxt, ret) < 0) 951 goto err0; 952 } else { 953 if (xdr_stream_encode_item_absent(&sctxt->sc_stream) < 0) 954 goto err0; 955 } 956 957 ret = svc_rdma_send_reply_msg(rdma, sctxt, rctxt, rqstp); 958 if (ret < 0) 959 goto err1; 960 return 0; 961 962 err2: 963 if (ret != -E2BIG && ret != -EINVAL) 964 goto err1; 965 966 /* Send completion releases payload pages that were part 967 * of previously posted RDMA Writes. 968 */ 969 svc_rdma_save_io_pages(rqstp, sctxt); 970 svc_rdma_send_error_msg(rdma, sctxt, rctxt, ret); 971 return 0; 972 973 err1: 974 svc_rdma_send_ctxt_put(rdma, sctxt); 975 err0: 976 trace_svcrdma_send_err(rqstp, ret); 977 set_bit(XPT_CLOSE, &xprt->xpt_flags); 978 return -ENOTCONN; 979} 980 981/** 982 * svc_rdma_read_payload - special processing for a READ payload 983 * @rqstp: svc_rqst to operate on 984 * @offset: payload's byte offset in @xdr 985 * @length: size of payload, in bytes 986 * 987 * Returns zero on success. 988 * 989 * For the moment, just record the xdr_buf location of the READ 990 * payload. svc_rdma_sendto will use that location later when 991 * we actually send the payload. 992 */ 993int svc_rdma_read_payload(struct svc_rqst *rqstp, unsigned int offset, 994 unsigned int length) 995{ 996 struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt; 997 998 /* XXX: Just one READ payload slot for now, since our 999 * transport implementation currently supports only one 1000 * Write chunk. 1001 */ 1002 rctxt->rc_read_payload_offset = offset; 1003 rctxt->rc_read_payload_length = length; 1004 1005 return 0; 1006} 1007