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 if (wc->status != IB_WC_WR_FLUSH_ERR) 276 pr_err("svcrdma: Send: %s (%u/0x%x)\n", 277 ib_wc_status_msg(wc->status), 278 wc->status, wc->vendor_err); 279 } 280 281 svc_xprt_put(&rdma->sc_xprt); 282 } 283 284 /** 285 * svc_rdma_send - Post a single Send WR 286 * @rdma: transport on which to post the WR 287 * @wr: prepared Send WR to post 288 * 289 * Returns zero the Send WR was posted successfully. Otherwise, a 290 * negative errno is returned. 291 */ 292 int svc_rdma_send(struct svcxprt_rdma *rdma, struct ib_send_wr *wr) 293 { 294 int ret; 295 296 might_sleep(); 297 298 /* If the SQ is full, wait until an SQ entry is available */ 299 while (1) { 300 if ((atomic_dec_return(&rdma->sc_sq_avail) < 0)) { 301 atomic_inc(&rdma_stat_sq_starve); 302 trace_svcrdma_sq_full(rdma); 303 atomic_inc(&rdma->sc_sq_avail); 304 wait_event(rdma->sc_send_wait, 305 atomic_read(&rdma->sc_sq_avail) > 1); 306 if (test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags)) 307 return -ENOTCONN; 308 trace_svcrdma_sq_retry(rdma); 309 continue; 310 } 311 312 svc_xprt_get(&rdma->sc_xprt); 313 ret = ib_post_send(rdma->sc_qp, wr, NULL); 314 trace_svcrdma_post_send(wr, ret); 315 if (ret) { 316 set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); 317 svc_xprt_put(&rdma->sc_xprt); 318 wake_up(&rdma->sc_send_wait); 319 } 320 break; 321 } 322 return ret; 323 } 324 325 static u32 xdr_padsize(u32 len) 326 { 327 return (len & 3) ? (4 - (len & 3)) : 0; 328 } 329 330 /* Returns length of transport header, in bytes. 331 */ 332 static unsigned int svc_rdma_reply_hdr_len(__be32 *rdma_resp) 333 { 334 unsigned int nsegs; 335 __be32 *p; 336 337 p = rdma_resp; 338 339 /* RPC-over-RDMA V1 replies never have a Read list. */ 340 p += rpcrdma_fixed_maxsz + 1; 341 342 /* Skip Write list. */ 343 while (*p++ != xdr_zero) { 344 nsegs = be32_to_cpup(p++); 345 p += nsegs * rpcrdma_segment_maxsz; 346 } 347 348 /* Skip Reply chunk. */ 349 if (*p++ != xdr_zero) { 350 nsegs = be32_to_cpup(p++); 351 p += nsegs * rpcrdma_segment_maxsz; 352 } 353 354 return (unsigned long)p - (unsigned long)rdma_resp; 355 } 356 357 /* One Write chunk is copied from Call transport header to Reply 358 * transport header. Each segment's length field is updated to 359 * reflect number of bytes consumed in the segment. 360 * 361 * Returns number of segments in this chunk. 362 */ 363 static unsigned int xdr_encode_write_chunk(__be32 *dst, __be32 *src, 364 unsigned int remaining) 365 { 366 unsigned int i, nsegs; 367 u32 seg_len; 368 369 /* Write list discriminator */ 370 *dst++ = *src++; 371 372 /* number of segments in this chunk */ 373 nsegs = be32_to_cpup(src); 374 *dst++ = *src++; 375 376 for (i = nsegs; i; i--) { 377 /* segment's RDMA handle */ 378 *dst++ = *src++; 379 380 /* bytes returned in this segment */ 381 seg_len = be32_to_cpu(*src); 382 if (remaining >= seg_len) { 383 /* entire segment was consumed */ 384 *dst = *src; 385 remaining -= seg_len; 386 } else { 387 /* segment only partly filled */ 388 *dst = cpu_to_be32(remaining); 389 remaining = 0; 390 } 391 dst++; src++; 392 393 /* segment's RDMA offset */ 394 *dst++ = *src++; 395 *dst++ = *src++; 396 } 397 398 return nsegs; 399 } 400 401 /* The client provided a Write list in the Call message. Fill in 402 * the segments in the first Write chunk in the Reply's transport 403 * header with the number of bytes consumed in each segment. 404 * Remaining chunks are returned unused. 405 * 406 * Assumptions: 407 * - Client has provided only one Write chunk 408 */ 409 static void svc_rdma_xdr_encode_write_list(__be32 *rdma_resp, __be32 *wr_ch, 410 unsigned int consumed) 411 { 412 unsigned int nsegs; 413 __be32 *p, *q; 414 415 /* RPC-over-RDMA V1 replies never have a Read list. */ 416 p = rdma_resp + rpcrdma_fixed_maxsz + 1; 417 418 q = wr_ch; 419 while (*q != xdr_zero) { 420 nsegs = xdr_encode_write_chunk(p, q, consumed); 421 q += 2 + nsegs * rpcrdma_segment_maxsz; 422 p += 2 + nsegs * rpcrdma_segment_maxsz; 423 consumed = 0; 424 } 425 426 /* Terminate Write list */ 427 *p++ = xdr_zero; 428 429 /* Reply chunk discriminator; may be replaced later */ 430 *p = xdr_zero; 431 } 432 433 /* The client provided a Reply chunk in the Call message. Fill in 434 * the segments in the Reply chunk in the Reply message with the 435 * number of bytes consumed in each segment. 436 * 437 * Assumptions: 438 * - Reply can always fit in the provided Reply chunk 439 */ 440 static void svc_rdma_xdr_encode_reply_chunk(__be32 *rdma_resp, __be32 *rp_ch, 441 unsigned int consumed) 442 { 443 __be32 *p; 444 445 /* Find the Reply chunk in the Reply's xprt header. 446 * RPC-over-RDMA V1 replies never have a Read list. 447 */ 448 p = rdma_resp + rpcrdma_fixed_maxsz + 1; 449 450 /* Skip past Write list */ 451 while (*p++ != xdr_zero) 452 p += 1 + be32_to_cpup(p) * rpcrdma_segment_maxsz; 453 454 xdr_encode_write_chunk(p, rp_ch, consumed); 455 } 456 457 /* Parse the RPC Call's transport header. 458 */ 459 static void svc_rdma_get_write_arrays(__be32 *rdma_argp, 460 __be32 **write, __be32 **reply) 461 { 462 __be32 *p; 463 464 p = rdma_argp + rpcrdma_fixed_maxsz; 465 466 /* Read list */ 467 while (*p++ != xdr_zero) 468 p += 5; 469 470 /* Write list */ 471 if (*p != xdr_zero) { 472 *write = p; 473 while (*p++ != xdr_zero) 474 p += 1 + be32_to_cpu(*p) * 4; 475 } else { 476 *write = NULL; 477 p++; 478 } 479 480 /* Reply chunk */ 481 if (*p != xdr_zero) 482 *reply = p; 483 else 484 *reply = NULL; 485 } 486 487 /* RPC-over-RDMA Version One private extension: Remote Invalidation. 488 * Responder's choice: requester signals it can handle Send With 489 * Invalidate, and responder chooses one rkey to invalidate. 490 * 491 * Find a candidate rkey to invalidate when sending a reply. Picks the 492 * first R_key it finds in the chunk lists. 493 * 494 * Returns zero if RPC's chunk lists are empty. 495 */ 496 static u32 svc_rdma_get_inv_rkey(__be32 *rdma_argp, 497 __be32 *wr_lst, __be32 *rp_ch) 498 { 499 __be32 *p; 500 501 p = rdma_argp + rpcrdma_fixed_maxsz; 502 if (*p != xdr_zero) 503 p += 2; 504 else if (wr_lst && be32_to_cpup(wr_lst + 1)) 505 p = wr_lst + 2; 506 else if (rp_ch && be32_to_cpup(rp_ch + 1)) 507 p = rp_ch + 2; 508 else 509 return 0; 510 return be32_to_cpup(p); 511 } 512 513 static int svc_rdma_dma_map_page(struct svcxprt_rdma *rdma, 514 struct svc_rdma_send_ctxt *ctxt, 515 struct page *page, 516 unsigned long offset, 517 unsigned int len) 518 { 519 struct ib_device *dev = rdma->sc_cm_id->device; 520 dma_addr_t dma_addr; 521 522 dma_addr = ib_dma_map_page(dev, page, offset, len, DMA_TO_DEVICE); 523 if (ib_dma_mapping_error(dev, dma_addr)) 524 goto out_maperr; 525 526 ctxt->sc_sges[ctxt->sc_cur_sge_no].addr = dma_addr; 527 ctxt->sc_sges[ctxt->sc_cur_sge_no].length = len; 528 ctxt->sc_send_wr.num_sge++; 529 return 0; 530 531 out_maperr: 532 trace_svcrdma_dma_map_page(rdma, page); 533 return -EIO; 534 } 535 536 /* ib_dma_map_page() is used here because svc_rdma_dma_unmap() 537 * handles DMA-unmap and it uses ib_dma_unmap_page() exclusively. 538 */ 539 static int svc_rdma_dma_map_buf(struct svcxprt_rdma *rdma, 540 struct svc_rdma_send_ctxt *ctxt, 541 unsigned char *base, 542 unsigned int len) 543 { 544 return svc_rdma_dma_map_page(rdma, ctxt, virt_to_page(base), 545 offset_in_page(base), len); 546 } 547 548 /** 549 * svc_rdma_sync_reply_hdr - DMA sync the transport header buffer 550 * @rdma: controlling transport 551 * @ctxt: send_ctxt for the Send WR 552 * @len: length of transport header 553 * 554 */ 555 void svc_rdma_sync_reply_hdr(struct svcxprt_rdma *rdma, 556 struct svc_rdma_send_ctxt *ctxt, 557 unsigned int len) 558 { 559 ctxt->sc_sges[0].length = len; 560 ctxt->sc_send_wr.num_sge++; 561 ib_dma_sync_single_for_device(rdma->sc_pd->device, 562 ctxt->sc_sges[0].addr, len, 563 DMA_TO_DEVICE); 564 } 565 566 /* svc_rdma_map_reply_msg - Map the buffer holding RPC message 567 * @rdma: controlling transport 568 * @ctxt: send_ctxt for the Send WR 569 * @xdr: prepared xdr_buf containing RPC message 570 * @wr_lst: pointer to Call header's Write list, or NULL 571 * 572 * Load the xdr_buf into the ctxt's sge array, and DMA map each 573 * element as it is added. 574 * 575 * Returns zero on success, or a negative errno on failure. 576 */ 577 int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma, 578 struct svc_rdma_send_ctxt *ctxt, 579 struct xdr_buf *xdr, __be32 *wr_lst) 580 { 581 unsigned int len, remaining; 582 unsigned long page_off; 583 struct page **ppages; 584 unsigned char *base; 585 u32 xdr_pad; 586 int ret; 587 588 if (++ctxt->sc_cur_sge_no >= rdma->sc_max_send_sges) 589 return -EIO; 590 ret = svc_rdma_dma_map_buf(rdma, ctxt, 591 xdr->head[0].iov_base, 592 xdr->head[0].iov_len); 593 if (ret < 0) 594 return ret; 595 596 /* If a Write chunk is present, the xdr_buf's page list 597 * is not included inline. However the Upper Layer may 598 * have added XDR padding in the tail buffer, and that 599 * should not be included inline. 600 */ 601 if (wr_lst) { 602 base = xdr->tail[0].iov_base; 603 len = xdr->tail[0].iov_len; 604 xdr_pad = xdr_padsize(xdr->page_len); 605 606 if (len && xdr_pad) { 607 base += xdr_pad; 608 len -= xdr_pad; 609 } 610 611 goto tail; 612 } 613 614 ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT); 615 page_off = xdr->page_base & ~PAGE_MASK; 616 remaining = xdr->page_len; 617 while (remaining) { 618 len = min_t(u32, PAGE_SIZE - page_off, remaining); 619 620 if (++ctxt->sc_cur_sge_no >= rdma->sc_max_send_sges) 621 return -EIO; 622 ret = svc_rdma_dma_map_page(rdma, ctxt, *ppages++, 623 page_off, len); 624 if (ret < 0) 625 return ret; 626 627 remaining -= len; 628 page_off = 0; 629 } 630 631 base = xdr->tail[0].iov_base; 632 len = xdr->tail[0].iov_len; 633 tail: 634 if (len) { 635 if (++ctxt->sc_cur_sge_no >= rdma->sc_max_send_sges) 636 return -EIO; 637 ret = svc_rdma_dma_map_buf(rdma, ctxt, base, len); 638 if (ret < 0) 639 return ret; 640 } 641 642 return 0; 643 } 644 645 /* The svc_rqst and all resources it owns are released as soon as 646 * svc_rdma_sendto returns. Transfer pages under I/O to the ctxt 647 * so they are released by the Send completion handler. 648 */ 649 static void svc_rdma_save_io_pages(struct svc_rqst *rqstp, 650 struct svc_rdma_send_ctxt *ctxt) 651 { 652 int i, pages = rqstp->rq_next_page - rqstp->rq_respages; 653 654 ctxt->sc_page_count += pages; 655 for (i = 0; i < pages; i++) { 656 ctxt->sc_pages[i] = rqstp->rq_respages[i]; 657 rqstp->rq_respages[i] = NULL; 658 } 659 rqstp->rq_next_page = rqstp->rq_respages + 1; 660 } 661 662 /* Prepare the portion of the RPC Reply that will be transmitted 663 * via RDMA Send. The RPC-over-RDMA transport header is prepared 664 * in sc_sges[0], and the RPC xdr_buf is prepared in following sges. 665 * 666 * Depending on whether a Write list or Reply chunk is present, 667 * the server may send all, a portion of, or none of the xdr_buf. 668 * In the latter case, only the transport header (sc_sges[0]) is 669 * transmitted. 670 * 671 * RDMA Send is the last step of transmitting an RPC reply. Pages 672 * involved in the earlier RDMA Writes are here transferred out 673 * of the rqstp and into the ctxt's page array. These pages are 674 * DMA unmapped by each Write completion, but the subsequent Send 675 * completion finally releases these pages. 676 * 677 * Assumptions: 678 * - The Reply's transport header will never be larger than a page. 679 */ 680 static int svc_rdma_send_reply_msg(struct svcxprt_rdma *rdma, 681 struct svc_rdma_send_ctxt *ctxt, 682 __be32 *rdma_argp, 683 struct svc_rqst *rqstp, 684 __be32 *wr_lst, __be32 *rp_ch) 685 { 686 int ret; 687 688 if (!rp_ch) { 689 ret = svc_rdma_map_reply_msg(rdma, ctxt, 690 &rqstp->rq_res, wr_lst); 691 if (ret < 0) 692 return ret; 693 } 694 695 svc_rdma_save_io_pages(rqstp, ctxt); 696 697 ctxt->sc_send_wr.opcode = IB_WR_SEND; 698 if (rdma->sc_snd_w_inv) { 699 ctxt->sc_send_wr.ex.invalidate_rkey = 700 svc_rdma_get_inv_rkey(rdma_argp, wr_lst, rp_ch); 701 if (ctxt->sc_send_wr.ex.invalidate_rkey) 702 ctxt->sc_send_wr.opcode = IB_WR_SEND_WITH_INV; 703 } 704 dprintk("svcrdma: posting Send WR with %u sge(s)\n", 705 ctxt->sc_send_wr.num_sge); 706 return svc_rdma_send(rdma, &ctxt->sc_send_wr); 707 } 708 709 /* Given the client-provided Write and Reply chunks, the server was not 710 * able to form a complete reply. Return an RDMA_ERROR message so the 711 * client can retire this RPC transaction. As above, the Send completion 712 * routine releases payload pages that were part of a previous RDMA Write. 713 * 714 * Remote Invalidation is skipped for simplicity. 715 */ 716 static int svc_rdma_send_error_msg(struct svcxprt_rdma *rdma, 717 struct svc_rdma_send_ctxt *ctxt, 718 struct svc_rqst *rqstp) 719 { 720 __be32 *p; 721 int ret; 722 723 p = ctxt->sc_xprt_buf; 724 trace_svcrdma_err_chunk(*p); 725 p += 3; 726 *p++ = rdma_error; 727 *p = err_chunk; 728 svc_rdma_sync_reply_hdr(rdma, ctxt, RPCRDMA_HDRLEN_ERR); 729 730 svc_rdma_save_io_pages(rqstp, ctxt); 731 732 ctxt->sc_send_wr.opcode = IB_WR_SEND; 733 ret = svc_rdma_send(rdma, &ctxt->sc_send_wr); 734 if (ret) { 735 svc_rdma_send_ctxt_put(rdma, ctxt); 736 return ret; 737 } 738 739 return 0; 740 } 741 742 void svc_rdma_prep_reply_hdr(struct svc_rqst *rqstp) 743 { 744 } 745 746 /** 747 * svc_rdma_sendto - Transmit an RPC reply 748 * @rqstp: processed RPC request, reply XDR already in ::rq_res 749 * 750 * Any resources still associated with @rqstp are released upon return. 751 * If no reply message was possible, the connection is closed. 752 * 753 * Returns: 754 * %0 if an RPC reply has been successfully posted, 755 * %-ENOMEM if a resource shortage occurred (connection is lost), 756 * %-ENOTCONN if posting failed (connection is lost). 757 */ 758 int svc_rdma_sendto(struct svc_rqst *rqstp) 759 { 760 struct svc_xprt *xprt = rqstp->rq_xprt; 761 struct svcxprt_rdma *rdma = 762 container_of(xprt, struct svcxprt_rdma, sc_xprt); 763 struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt; 764 __be32 *p, *rdma_argp, *rdma_resp, *wr_lst, *rp_ch; 765 struct xdr_buf *xdr = &rqstp->rq_res; 766 struct svc_rdma_send_ctxt *sctxt; 767 int ret; 768 769 rdma_argp = rctxt->rc_recv_buf; 770 svc_rdma_get_write_arrays(rdma_argp, &wr_lst, &rp_ch); 771 772 /* Create the RDMA response header. xprt->xpt_mutex, 773 * acquired in svc_send(), serializes RPC replies. The 774 * code path below that inserts the credit grant value 775 * into each transport header runs only inside this 776 * critical section. 777 */ 778 ret = -ENOMEM; 779 sctxt = svc_rdma_send_ctxt_get(rdma); 780 if (!sctxt) 781 goto err0; 782 rdma_resp = sctxt->sc_xprt_buf; 783 784 p = rdma_resp; 785 *p++ = *rdma_argp; 786 *p++ = *(rdma_argp + 1); 787 *p++ = rdma->sc_fc_credits; 788 *p++ = rp_ch ? rdma_nomsg : rdma_msg; 789 790 /* Start with empty chunks */ 791 *p++ = xdr_zero; 792 *p++ = xdr_zero; 793 *p = xdr_zero; 794 795 if (wr_lst) { 796 /* XXX: Presume the client sent only one Write chunk */ 797 ret = svc_rdma_send_write_chunk(rdma, wr_lst, xdr); 798 if (ret < 0) 799 goto err2; 800 svc_rdma_xdr_encode_write_list(rdma_resp, wr_lst, ret); 801 } 802 if (rp_ch) { 803 ret = svc_rdma_send_reply_chunk(rdma, rp_ch, wr_lst, xdr); 804 if (ret < 0) 805 goto err2; 806 svc_rdma_xdr_encode_reply_chunk(rdma_resp, rp_ch, ret); 807 } 808 809 svc_rdma_sync_reply_hdr(rdma, sctxt, svc_rdma_reply_hdr_len(rdma_resp)); 810 ret = svc_rdma_send_reply_msg(rdma, sctxt, rdma_argp, rqstp, 811 wr_lst, rp_ch); 812 if (ret < 0) 813 goto err1; 814 ret = 0; 815 816 out: 817 rqstp->rq_xprt_ctxt = NULL; 818 svc_rdma_recv_ctxt_put(rdma, rctxt); 819 return ret; 820 821 err2: 822 if (ret != -E2BIG && ret != -EINVAL) 823 goto err1; 824 825 ret = svc_rdma_send_error_msg(rdma, sctxt, rqstp); 826 if (ret < 0) 827 goto err1; 828 ret = 0; 829 goto out; 830 831 err1: 832 svc_rdma_send_ctxt_put(rdma, sctxt); 833 err0: 834 trace_svcrdma_send_failed(rqstp, ret); 835 set_bit(XPT_CLOSE, &xprt->xpt_flags); 836 ret = -ENOTCONN; 837 goto out; 838 } 839