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 static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc); 115 116 static struct svc_rdma_send_ctxt * 117 svc_rdma_send_ctxt_alloc(struct svcxprt_rdma *rdma) 118 { 119 int node = ibdev_to_node(rdma->sc_cm_id->device); 120 struct svc_rdma_send_ctxt *ctxt; 121 dma_addr_t addr; 122 void *buffer; 123 int i; 124 125 ctxt = kzalloc_node(struct_size(ctxt, sc_sges, rdma->sc_max_send_sges), 126 GFP_KERNEL, node); 127 if (!ctxt) 128 goto fail0; 129 buffer = kmalloc_node(rdma->sc_max_req_size, GFP_KERNEL, node); 130 if (!buffer) 131 goto fail1; 132 addr = ib_dma_map_single(rdma->sc_pd->device, buffer, 133 rdma->sc_max_req_size, DMA_TO_DEVICE); 134 if (ib_dma_mapping_error(rdma->sc_pd->device, addr)) 135 goto fail2; 136 137 svc_rdma_send_cid_init(rdma, &ctxt->sc_cid); 138 139 ctxt->sc_rdma = rdma; 140 ctxt->sc_send_wr.next = NULL; 141 ctxt->sc_send_wr.wr_cqe = &ctxt->sc_cqe; 142 ctxt->sc_send_wr.sg_list = ctxt->sc_sges; 143 ctxt->sc_send_wr.send_flags = IB_SEND_SIGNALED; 144 ctxt->sc_cqe.done = svc_rdma_wc_send; 145 INIT_LIST_HEAD(&ctxt->sc_write_info_list); 146 ctxt->sc_xprt_buf = buffer; 147 xdr_buf_init(&ctxt->sc_hdrbuf, ctxt->sc_xprt_buf, 148 rdma->sc_max_req_size); 149 ctxt->sc_sges[0].addr = addr; 150 151 for (i = 0; i < rdma->sc_max_send_sges; i++) 152 ctxt->sc_sges[i].lkey = rdma->sc_pd->local_dma_lkey; 153 return ctxt; 154 155 fail2: 156 kfree(buffer); 157 fail1: 158 kfree(ctxt); 159 fail0: 160 return NULL; 161 } 162 163 /** 164 * svc_rdma_send_ctxts_destroy - Release all send_ctxt's for an xprt 165 * @rdma: svcxprt_rdma being torn down 166 * 167 */ 168 void svc_rdma_send_ctxts_destroy(struct svcxprt_rdma *rdma) 169 { 170 struct svc_rdma_send_ctxt *ctxt; 171 struct llist_node *node; 172 173 while ((node = llist_del_first(&rdma->sc_send_ctxts)) != NULL) { 174 ctxt = llist_entry(node, struct svc_rdma_send_ctxt, sc_node); 175 ib_dma_unmap_single(rdma->sc_pd->device, 176 ctxt->sc_sges[0].addr, 177 rdma->sc_max_req_size, 178 DMA_TO_DEVICE); 179 kfree(ctxt->sc_xprt_buf); 180 kfree(ctxt); 181 } 182 } 183 184 /** 185 * svc_rdma_send_ctxt_get - Get a free send_ctxt 186 * @rdma: controlling svcxprt_rdma 187 * 188 * Returns a ready-to-use send_ctxt, or NULL if none are 189 * available and a fresh one cannot be allocated. 190 */ 191 struct svc_rdma_send_ctxt *svc_rdma_send_ctxt_get(struct svcxprt_rdma *rdma) 192 { 193 struct svc_rdma_send_ctxt *ctxt; 194 struct llist_node *node; 195 196 spin_lock(&rdma->sc_send_lock); 197 node = llist_del_first(&rdma->sc_send_ctxts); 198 spin_unlock(&rdma->sc_send_lock); 199 if (!node) 200 goto out_empty; 201 202 ctxt = llist_entry(node, struct svc_rdma_send_ctxt, sc_node); 203 204 out: 205 rpcrdma_set_xdrlen(&ctxt->sc_hdrbuf, 0); 206 xdr_init_encode(&ctxt->sc_stream, &ctxt->sc_hdrbuf, 207 ctxt->sc_xprt_buf, NULL); 208 209 svc_rdma_cc_init(rdma, &ctxt->sc_reply_info.wi_cc); 210 ctxt->sc_send_wr.num_sge = 0; 211 ctxt->sc_cur_sge_no = 0; 212 ctxt->sc_page_count = 0; 213 ctxt->sc_wr_chain = &ctxt->sc_send_wr; 214 ctxt->sc_sqecount = 1; 215 216 return ctxt; 217 218 out_empty: 219 ctxt = svc_rdma_send_ctxt_alloc(rdma); 220 if (!ctxt) 221 return NULL; 222 goto out; 223 } 224 225 static void svc_rdma_send_ctxt_release(struct svcxprt_rdma *rdma, 226 struct svc_rdma_send_ctxt *ctxt) 227 { 228 struct ib_device *device = rdma->sc_cm_id->device; 229 unsigned int i; 230 231 svc_rdma_write_chunk_release(rdma, ctxt); 232 svc_rdma_reply_chunk_release(rdma, ctxt); 233 234 if (ctxt->sc_page_count) 235 release_pages(ctxt->sc_pages, ctxt->sc_page_count); 236 237 /* The first SGE contains the transport header, which 238 * remains mapped until @ctxt is destroyed. 239 */ 240 for (i = 1; i < ctxt->sc_send_wr.num_sge; i++) { 241 trace_svcrdma_dma_unmap_page(&ctxt->sc_cid, 242 ctxt->sc_sges[i].addr, 243 ctxt->sc_sges[i].length); 244 ib_dma_unmap_page(device, 245 ctxt->sc_sges[i].addr, 246 ctxt->sc_sges[i].length, 247 DMA_TO_DEVICE); 248 } 249 250 llist_add(&ctxt->sc_node, &rdma->sc_send_ctxts); 251 } 252 253 static void svc_rdma_send_ctxt_put_async(struct work_struct *work) 254 { 255 struct svc_rdma_send_ctxt *ctxt; 256 257 ctxt = container_of(work, struct svc_rdma_send_ctxt, sc_work); 258 svc_rdma_send_ctxt_release(ctxt->sc_rdma, ctxt); 259 } 260 261 /** 262 * svc_rdma_send_ctxt_put - Return send_ctxt to free list 263 * @rdma: controlling svcxprt_rdma 264 * @ctxt: object to return to the free list 265 * 266 * Pages left in sc_pages are DMA unmapped and released. 267 */ 268 void svc_rdma_send_ctxt_put(struct svcxprt_rdma *rdma, 269 struct svc_rdma_send_ctxt *ctxt) 270 { 271 INIT_WORK(&ctxt->sc_work, svc_rdma_send_ctxt_put_async); 272 queue_work(svcrdma_wq, &ctxt->sc_work); 273 } 274 275 /** 276 * svc_rdma_wake_send_waiters - manage Send Queue accounting 277 * @rdma: controlling transport 278 * @avail: Number of additional SQEs that are now available 279 * 280 */ 281 void svc_rdma_wake_send_waiters(struct svcxprt_rdma *rdma, int avail) 282 { 283 atomic_add(avail, &rdma->sc_sq_avail); 284 smp_mb__after_atomic(); 285 if (unlikely(waitqueue_active(&rdma->sc_send_wait))) 286 wake_up(&rdma->sc_send_wait); 287 } 288 289 /** 290 * svc_rdma_wc_send - Invoked by RDMA provider for each polled Send WC 291 * @cq: Completion Queue context 292 * @wc: Work Completion object 293 * 294 * NB: The svc_xprt/svcxprt_rdma is pinned whenever it's possible that 295 * the Send completion handler could be running. 296 */ 297 static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc) 298 { 299 struct svcxprt_rdma *rdma = cq->cq_context; 300 struct ib_cqe *cqe = wc->wr_cqe; 301 struct svc_rdma_send_ctxt *ctxt = 302 container_of(cqe, struct svc_rdma_send_ctxt, sc_cqe); 303 304 svc_rdma_wake_send_waiters(rdma, ctxt->sc_sqecount); 305 306 if (unlikely(wc->status != IB_WC_SUCCESS)) 307 goto flushed; 308 309 trace_svcrdma_wc_send(&ctxt->sc_cid); 310 svc_rdma_send_ctxt_put(rdma, ctxt); 311 return; 312 313 flushed: 314 if (wc->status != IB_WC_WR_FLUSH_ERR) 315 trace_svcrdma_wc_send_err(wc, &ctxt->sc_cid); 316 else 317 trace_svcrdma_wc_send_flush(wc, &ctxt->sc_cid); 318 svc_rdma_send_ctxt_put(rdma, ctxt); 319 svc_xprt_deferred_close(&rdma->sc_xprt); 320 } 321 322 /** 323 * svc_rdma_post_send - Post a WR chain to the Send Queue 324 * @rdma: transport context 325 * @ctxt: WR chain to post 326 * 327 * Copy fields in @ctxt to stack variables in order to guarantee 328 * that these values remain available after the ib_post_send() call. 329 * In some error flow cases, svc_rdma_wc_send() releases @ctxt. 330 * 331 * Note there is potential for starvation when the Send Queue is 332 * full because there is no order to when waiting threads are 333 * awoken. The transport is typically provisioned with a deep 334 * enough Send Queue that SQ exhaustion should be a rare event. 335 * 336 * Return values: 337 * %0: @ctxt's WR chain was posted successfully 338 * %-ENOTCONN: The connection was lost 339 */ 340 int svc_rdma_post_send(struct svcxprt_rdma *rdma, 341 struct svc_rdma_send_ctxt *ctxt) 342 { 343 struct ib_send_wr *first_wr = ctxt->sc_wr_chain; 344 struct ib_send_wr *send_wr = &ctxt->sc_send_wr; 345 const struct ib_send_wr *bad_wr = first_wr; 346 struct rpc_rdma_cid cid = ctxt->sc_cid; 347 int ret, sqecount = ctxt->sc_sqecount; 348 349 might_sleep(); 350 351 /* Sync the transport header buffer */ 352 ib_dma_sync_single_for_device(rdma->sc_pd->device, 353 send_wr->sg_list[0].addr, 354 send_wr->sg_list[0].length, 355 DMA_TO_DEVICE); 356 357 /* If the SQ is full, wait until an SQ entry is available */ 358 while (!test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags)) { 359 if (atomic_sub_return(sqecount, &rdma->sc_sq_avail) < 0) { 360 svc_rdma_wake_send_waiters(rdma, sqecount); 361 362 /* When the transport is torn down, assume 363 * ib_drain_sq() will trigger enough Send 364 * completions to wake us. The XPT_CLOSE test 365 * above should then cause the while loop to 366 * exit. 367 */ 368 percpu_counter_inc(&svcrdma_stat_sq_starve); 369 trace_svcrdma_sq_full(rdma, &cid); 370 wait_event(rdma->sc_send_wait, 371 atomic_read(&rdma->sc_sq_avail) > 0); 372 trace_svcrdma_sq_retry(rdma, &cid); 373 continue; 374 } 375 376 trace_svcrdma_post_send(ctxt); 377 ret = ib_post_send(rdma->sc_qp, first_wr, &bad_wr); 378 if (ret) { 379 trace_svcrdma_sq_post_err(rdma, &cid, ret); 380 svc_xprt_deferred_close(&rdma->sc_xprt); 381 382 /* If even one WR was posted, there will be a 383 * Send completion that bumps sc_sq_avail. 384 */ 385 if (bad_wr == first_wr) { 386 svc_rdma_wake_send_waiters(rdma, sqecount); 387 break; 388 } 389 } 390 return 0; 391 } 392 return -ENOTCONN; 393 } 394 395 /** 396 * svc_rdma_encode_read_list - Encode RPC Reply's Read chunk list 397 * @sctxt: Send context for the RPC Reply 398 * 399 * Return values: 400 * On success, returns length in bytes of the Reply XDR buffer 401 * that was consumed by the Reply Read list 402 * %-EMSGSIZE on XDR buffer overflow 403 */ 404 static ssize_t svc_rdma_encode_read_list(struct svc_rdma_send_ctxt *sctxt) 405 { 406 /* RPC-over-RDMA version 1 replies never have a Read list. */ 407 return xdr_stream_encode_item_absent(&sctxt->sc_stream); 408 } 409 410 /** 411 * svc_rdma_encode_write_segment - Encode one Write segment 412 * @sctxt: Send context for the RPC Reply 413 * @chunk: Write chunk to push 414 * @remaining: remaining bytes of the payload left in the Write chunk 415 * @segno: which segment in the chunk 416 * 417 * Return values: 418 * On success, returns length in bytes of the Reply XDR buffer 419 * that was consumed by the Write segment, and updates @remaining 420 * %-EMSGSIZE on XDR buffer overflow 421 */ 422 static ssize_t svc_rdma_encode_write_segment(struct svc_rdma_send_ctxt *sctxt, 423 const struct svc_rdma_chunk *chunk, 424 u32 *remaining, unsigned int segno) 425 { 426 const struct svc_rdma_segment *segment = &chunk->ch_segments[segno]; 427 const size_t len = rpcrdma_segment_maxsz * sizeof(__be32); 428 u32 length; 429 __be32 *p; 430 431 p = xdr_reserve_space(&sctxt->sc_stream, len); 432 if (!p) 433 return -EMSGSIZE; 434 435 length = min_t(u32, *remaining, segment->rs_length); 436 *remaining -= length; 437 xdr_encode_rdma_segment(p, segment->rs_handle, length, 438 segment->rs_offset); 439 trace_svcrdma_encode_wseg(sctxt, segno, segment->rs_handle, length, 440 segment->rs_offset); 441 return len; 442 } 443 444 /** 445 * svc_rdma_encode_write_chunk - Encode one Write chunk 446 * @sctxt: Send context for the RPC Reply 447 * @chunk: Write chunk to push 448 * 449 * Copy a Write chunk from the Call transport header to the 450 * Reply transport header. Update each segment's length field 451 * to reflect the number of bytes written in that segment. 452 * 453 * Return values: 454 * On success, returns length in bytes of the Reply XDR buffer 455 * that was consumed by the Write chunk 456 * %-EMSGSIZE on XDR buffer overflow 457 */ 458 static ssize_t svc_rdma_encode_write_chunk(struct svc_rdma_send_ctxt *sctxt, 459 const struct svc_rdma_chunk *chunk) 460 { 461 u32 remaining = chunk->ch_payload_length; 462 unsigned int segno; 463 ssize_t len, ret; 464 465 len = 0; 466 ret = xdr_stream_encode_item_present(&sctxt->sc_stream); 467 if (ret < 0) 468 return ret; 469 len += ret; 470 471 ret = xdr_stream_encode_u32(&sctxt->sc_stream, chunk->ch_segcount); 472 if (ret < 0) 473 return ret; 474 len += ret; 475 476 for (segno = 0; segno < chunk->ch_segcount; segno++) { 477 ret = svc_rdma_encode_write_segment(sctxt, chunk, &remaining, segno); 478 if (ret < 0) 479 return ret; 480 len += ret; 481 } 482 483 return len; 484 } 485 486 /** 487 * svc_rdma_encode_write_list - Encode RPC Reply's Write chunk list 488 * @rctxt: Reply context with information about the RPC Call 489 * @sctxt: Send context for the RPC Reply 490 * 491 * Return values: 492 * On success, returns length in bytes of the Reply XDR buffer 493 * that was consumed by the Reply's Write list 494 * %-EMSGSIZE on XDR buffer overflow 495 */ 496 static ssize_t svc_rdma_encode_write_list(struct svc_rdma_recv_ctxt *rctxt, 497 struct svc_rdma_send_ctxt *sctxt) 498 { 499 struct svc_rdma_chunk *chunk; 500 ssize_t len, ret; 501 502 len = 0; 503 pcl_for_each_chunk(chunk, &rctxt->rc_write_pcl) { 504 ret = svc_rdma_encode_write_chunk(sctxt, chunk); 505 if (ret < 0) 506 return ret; 507 len += ret; 508 } 509 510 /* Terminate the Write list */ 511 ret = xdr_stream_encode_item_absent(&sctxt->sc_stream); 512 if (ret < 0) 513 return ret; 514 515 return len + ret; 516 } 517 518 /** 519 * svc_rdma_encode_reply_chunk - Encode RPC Reply's Reply chunk 520 * @rctxt: Reply context with information about the RPC Call 521 * @sctxt: Send context for the RPC Reply 522 * @length: size in bytes of the payload in the Reply chunk 523 * 524 * Return values: 525 * On success, returns length in bytes of the Reply XDR buffer 526 * that was consumed by the Reply's Reply chunk 527 * %-EMSGSIZE on XDR buffer overflow 528 * %-E2BIG if the RPC message is larger than the Reply chunk 529 */ 530 static ssize_t 531 svc_rdma_encode_reply_chunk(struct svc_rdma_recv_ctxt *rctxt, 532 struct svc_rdma_send_ctxt *sctxt, 533 unsigned int length) 534 { 535 struct svc_rdma_chunk *chunk; 536 537 if (pcl_is_empty(&rctxt->rc_reply_pcl)) 538 return xdr_stream_encode_item_absent(&sctxt->sc_stream); 539 540 chunk = pcl_first_chunk(&rctxt->rc_reply_pcl); 541 if (length > chunk->ch_length) 542 return -E2BIG; 543 544 chunk->ch_payload_length = length; 545 return svc_rdma_encode_write_chunk(sctxt, chunk); 546 } 547 548 struct svc_rdma_map_data { 549 struct svcxprt_rdma *md_rdma; 550 struct svc_rdma_send_ctxt *md_ctxt; 551 }; 552 553 /** 554 * svc_rdma_page_dma_map - DMA map one page 555 * @data: pointer to arguments 556 * @page: struct page to DMA map 557 * @offset: offset into the page 558 * @len: number of bytes to map 559 * 560 * Returns: 561 * %0 if DMA mapping was successful 562 * %-EIO if the page cannot be DMA mapped 563 */ 564 static int svc_rdma_page_dma_map(void *data, struct page *page, 565 unsigned long offset, unsigned int len) 566 { 567 struct svc_rdma_map_data *args = data; 568 struct svcxprt_rdma *rdma = args->md_rdma; 569 struct svc_rdma_send_ctxt *ctxt = args->md_ctxt; 570 struct ib_device *dev = rdma->sc_cm_id->device; 571 dma_addr_t dma_addr; 572 573 ++ctxt->sc_cur_sge_no; 574 575 dma_addr = ib_dma_map_page(dev, page, offset, len, DMA_TO_DEVICE); 576 if (ib_dma_mapping_error(dev, dma_addr)) 577 goto out_maperr; 578 579 trace_svcrdma_dma_map_page(&ctxt->sc_cid, dma_addr, len); 580 ctxt->sc_sges[ctxt->sc_cur_sge_no].addr = dma_addr; 581 ctxt->sc_sges[ctxt->sc_cur_sge_no].length = len; 582 ctxt->sc_send_wr.num_sge++; 583 return 0; 584 585 out_maperr: 586 trace_svcrdma_dma_map_err(&ctxt->sc_cid, dma_addr, len); 587 return -EIO; 588 } 589 590 /** 591 * svc_rdma_iov_dma_map - DMA map an iovec 592 * @data: pointer to arguments 593 * @iov: kvec to DMA map 594 * 595 * ib_dma_map_page() is used here because svc_rdma_dma_unmap() 596 * handles DMA-unmap and it uses ib_dma_unmap_page() exclusively. 597 * 598 * Returns: 599 * %0 if DMA mapping was successful 600 * %-EIO if the iovec cannot be DMA mapped 601 */ 602 static int svc_rdma_iov_dma_map(void *data, const struct kvec *iov) 603 { 604 if (!iov->iov_len) 605 return 0; 606 return svc_rdma_page_dma_map(data, virt_to_page(iov->iov_base), 607 offset_in_page(iov->iov_base), 608 iov->iov_len); 609 } 610 611 /** 612 * svc_rdma_xb_dma_map - DMA map all segments of an xdr_buf 613 * @xdr: xdr_buf containing portion of an RPC message to transmit 614 * @data: pointer to arguments 615 * 616 * Returns: 617 * %0 if DMA mapping was successful 618 * %-EIO if DMA mapping failed 619 * 620 * On failure, any DMA mappings that have been already done must be 621 * unmapped by the caller. 622 */ 623 static int svc_rdma_xb_dma_map(const struct xdr_buf *xdr, void *data) 624 { 625 unsigned int len, remaining; 626 unsigned long pageoff; 627 struct page **ppages; 628 int ret; 629 630 ret = svc_rdma_iov_dma_map(data, &xdr->head[0]); 631 if (ret < 0) 632 return ret; 633 634 ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT); 635 pageoff = offset_in_page(xdr->page_base); 636 remaining = xdr->page_len; 637 while (remaining) { 638 len = min_t(u32, PAGE_SIZE - pageoff, remaining); 639 640 ret = svc_rdma_page_dma_map(data, *ppages++, pageoff, len); 641 if (ret < 0) 642 return ret; 643 644 remaining -= len; 645 pageoff = 0; 646 } 647 648 ret = svc_rdma_iov_dma_map(data, &xdr->tail[0]); 649 if (ret < 0) 650 return ret; 651 652 return xdr->len; 653 } 654 655 struct svc_rdma_pullup_data { 656 u8 *pd_dest; 657 unsigned int pd_length; 658 unsigned int pd_num_sges; 659 }; 660 661 /** 662 * svc_rdma_xb_count_sges - Count how many SGEs will be needed 663 * @xdr: xdr_buf containing portion of an RPC message to transmit 664 * @data: pointer to arguments 665 * 666 * Returns: 667 * Number of SGEs needed to Send the contents of @xdr inline 668 */ 669 static int svc_rdma_xb_count_sges(const struct xdr_buf *xdr, 670 void *data) 671 { 672 struct svc_rdma_pullup_data *args = data; 673 unsigned int remaining; 674 unsigned long offset; 675 676 if (xdr->head[0].iov_len) 677 ++args->pd_num_sges; 678 679 offset = offset_in_page(xdr->page_base); 680 remaining = xdr->page_len; 681 while (remaining) { 682 ++args->pd_num_sges; 683 remaining -= min_t(u32, PAGE_SIZE - offset, remaining); 684 offset = 0; 685 } 686 687 if (xdr->tail[0].iov_len) 688 ++args->pd_num_sges; 689 690 args->pd_length += xdr->len; 691 return 0; 692 } 693 694 /** 695 * svc_rdma_pull_up_needed - Determine whether to use pull-up 696 * @rdma: controlling transport 697 * @sctxt: send_ctxt for the Send WR 698 * @write_pcl: Write chunk list provided by client 699 * @xdr: xdr_buf containing RPC message to transmit 700 * 701 * Returns: 702 * %true if pull-up must be used 703 * %false otherwise 704 */ 705 static bool svc_rdma_pull_up_needed(const struct svcxprt_rdma *rdma, 706 const struct svc_rdma_send_ctxt *sctxt, 707 const struct svc_rdma_pcl *write_pcl, 708 const struct xdr_buf *xdr) 709 { 710 /* Resources needed for the transport header */ 711 struct svc_rdma_pullup_data args = { 712 .pd_length = sctxt->sc_hdrbuf.len, 713 .pd_num_sges = 1, 714 }; 715 int ret; 716 717 ret = pcl_process_nonpayloads(write_pcl, xdr, 718 svc_rdma_xb_count_sges, &args); 719 if (ret < 0) 720 return false; 721 722 if (args.pd_length < RPCRDMA_PULLUP_THRESH) 723 return true; 724 return args.pd_num_sges >= rdma->sc_max_send_sges; 725 } 726 727 /** 728 * svc_rdma_xb_linearize - Copy region of xdr_buf to flat buffer 729 * @xdr: xdr_buf containing portion of an RPC message to copy 730 * @data: pointer to arguments 731 * 732 * Returns: 733 * Always zero. 734 */ 735 static int svc_rdma_xb_linearize(const struct xdr_buf *xdr, 736 void *data) 737 { 738 struct svc_rdma_pullup_data *args = data; 739 unsigned int len, remaining; 740 unsigned long pageoff; 741 struct page **ppages; 742 743 if (xdr->head[0].iov_len) { 744 memcpy(args->pd_dest, xdr->head[0].iov_base, xdr->head[0].iov_len); 745 args->pd_dest += xdr->head[0].iov_len; 746 } 747 748 ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT); 749 pageoff = offset_in_page(xdr->page_base); 750 remaining = xdr->page_len; 751 while (remaining) { 752 len = min_t(u32, PAGE_SIZE - pageoff, remaining); 753 memcpy(args->pd_dest, page_address(*ppages) + pageoff, len); 754 remaining -= len; 755 args->pd_dest += len; 756 pageoff = 0; 757 ppages++; 758 } 759 760 if (xdr->tail[0].iov_len) { 761 memcpy(args->pd_dest, xdr->tail[0].iov_base, xdr->tail[0].iov_len); 762 args->pd_dest += xdr->tail[0].iov_len; 763 } 764 765 args->pd_length += xdr->len; 766 return 0; 767 } 768 769 /** 770 * svc_rdma_pull_up_reply_msg - Copy Reply into a single buffer 771 * @rdma: controlling transport 772 * @sctxt: send_ctxt for the Send WR; xprt hdr is already prepared 773 * @write_pcl: Write chunk list provided by client 774 * @xdr: prepared xdr_buf containing RPC message 775 * 776 * The device is not capable of sending the reply directly. 777 * Assemble the elements of @xdr into the transport header buffer. 778 * 779 * Assumptions: 780 * pull_up_needed has determined that @xdr will fit in the buffer. 781 * 782 * Returns: 783 * %0 if pull-up was successful 784 * %-EMSGSIZE if a buffer manipulation problem occurred 785 */ 786 static int svc_rdma_pull_up_reply_msg(const struct svcxprt_rdma *rdma, 787 struct svc_rdma_send_ctxt *sctxt, 788 const struct svc_rdma_pcl *write_pcl, 789 const struct xdr_buf *xdr) 790 { 791 struct svc_rdma_pullup_data args = { 792 .pd_dest = sctxt->sc_xprt_buf + sctxt->sc_hdrbuf.len, 793 }; 794 int ret; 795 796 ret = pcl_process_nonpayloads(write_pcl, xdr, 797 svc_rdma_xb_linearize, &args); 798 if (ret < 0) 799 return ret; 800 801 sctxt->sc_sges[0].length = sctxt->sc_hdrbuf.len + args.pd_length; 802 trace_svcrdma_send_pullup(sctxt, args.pd_length); 803 return 0; 804 } 805 806 /* svc_rdma_map_reply_msg - DMA map the buffer holding RPC message 807 * @rdma: controlling transport 808 * @sctxt: send_ctxt for the Send WR 809 * @write_pcl: Write chunk list provided by client 810 * @reply_pcl: Reply chunk provided by client 811 * @xdr: prepared xdr_buf containing RPC message 812 * 813 * Returns: 814 * %0 if DMA mapping was successful. 815 * %-EMSGSIZE if a buffer manipulation problem occurred 816 * %-EIO if DMA mapping failed 817 * 818 * The Send WR's num_sge field is set in all cases. 819 */ 820 int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma, 821 struct svc_rdma_send_ctxt *sctxt, 822 const struct svc_rdma_pcl *write_pcl, 823 const struct svc_rdma_pcl *reply_pcl, 824 const struct xdr_buf *xdr) 825 { 826 struct svc_rdma_map_data args = { 827 .md_rdma = rdma, 828 .md_ctxt = sctxt, 829 }; 830 831 /* Set up the (persistently-mapped) transport header SGE. */ 832 sctxt->sc_send_wr.num_sge = 1; 833 sctxt->sc_sges[0].length = sctxt->sc_hdrbuf.len; 834 835 /* If there is a Reply chunk, nothing follows the transport 836 * header, so there is nothing to map. 837 */ 838 if (!pcl_is_empty(reply_pcl)) 839 return 0; 840 841 /* For pull-up, svc_rdma_send() will sync the transport header. 842 * No additional DMA mapping is necessary. 843 */ 844 if (svc_rdma_pull_up_needed(rdma, sctxt, write_pcl, xdr)) 845 return svc_rdma_pull_up_reply_msg(rdma, sctxt, write_pcl, xdr); 846 847 return pcl_process_nonpayloads(write_pcl, xdr, 848 svc_rdma_xb_dma_map, &args); 849 } 850 851 /* The svc_rqst and all resources it owns are released as soon as 852 * svc_rdma_sendto returns. Transfer pages under I/O to the ctxt 853 * so they are released by the Send completion handler. 854 */ 855 static void svc_rdma_save_io_pages(struct svc_rqst *rqstp, 856 struct svc_rdma_send_ctxt *ctxt) 857 { 858 int i, pages = rqstp->rq_next_page - rqstp->rq_respages; 859 860 ctxt->sc_page_count += pages; 861 for (i = 0; i < pages; i++) { 862 ctxt->sc_pages[i] = rqstp->rq_respages[i]; 863 rqstp->rq_respages[i] = NULL; 864 } 865 866 /* Prevent svc_xprt_release from releasing pages in rq_pages */ 867 rqstp->rq_next_page = rqstp->rq_respages; 868 } 869 870 /* Prepare the portion of the RPC Reply that will be transmitted 871 * via RDMA Send. The RPC-over-RDMA transport header is prepared 872 * in sc_sges[0], and the RPC xdr_buf is prepared in following sges. 873 * 874 * Depending on whether a Write list or Reply chunk is present, 875 * the server may Send all, a portion of, or none of the xdr_buf. 876 * In the latter case, only the transport header (sc_sges[0]) is 877 * transmitted. 878 * 879 * Assumptions: 880 * - The Reply's transport header will never be larger than a page. 881 */ 882 static int svc_rdma_send_reply_msg(struct svcxprt_rdma *rdma, 883 struct svc_rdma_send_ctxt *sctxt, 884 const struct svc_rdma_recv_ctxt *rctxt, 885 struct svc_rqst *rqstp) 886 { 887 struct ib_send_wr *send_wr = &sctxt->sc_send_wr; 888 int ret; 889 890 ret = svc_rdma_map_reply_msg(rdma, sctxt, &rctxt->rc_write_pcl, 891 &rctxt->rc_reply_pcl, &rqstp->rq_res); 892 if (ret < 0) 893 return ret; 894 895 /* Transfer pages involved in RDMA Writes to the sctxt's 896 * page array. Completion handling releases these pages. 897 */ 898 svc_rdma_save_io_pages(rqstp, sctxt); 899 900 if (rctxt->rc_inv_rkey) { 901 send_wr->opcode = IB_WR_SEND_WITH_INV; 902 send_wr->ex.invalidate_rkey = rctxt->rc_inv_rkey; 903 } else { 904 send_wr->opcode = IB_WR_SEND; 905 } 906 907 return svc_rdma_post_send(rdma, sctxt); 908 } 909 910 /** 911 * svc_rdma_send_error_msg - Send an RPC/RDMA v1 error response 912 * @rdma: controlling transport context 913 * @sctxt: Send context for the response 914 * @rctxt: Receive context for incoming bad message 915 * @status: negative errno indicating error that occurred 916 * 917 * Given the client-provided Read, Write, and Reply chunks, the 918 * server was not able to parse the Call or form a complete Reply. 919 * Return an RDMA_ERROR message so the client can retire the RPC 920 * transaction. 921 * 922 * The caller does not have to release @sctxt. It is released by 923 * Send completion, or by this function on error. 924 */ 925 void svc_rdma_send_error_msg(struct svcxprt_rdma *rdma, 926 struct svc_rdma_send_ctxt *sctxt, 927 struct svc_rdma_recv_ctxt *rctxt, 928 int status) 929 { 930 __be32 *rdma_argp = rctxt->rc_recv_buf; 931 __be32 *p; 932 933 rpcrdma_set_xdrlen(&sctxt->sc_hdrbuf, 0); 934 xdr_init_encode(&sctxt->sc_stream, &sctxt->sc_hdrbuf, 935 sctxt->sc_xprt_buf, NULL); 936 937 p = xdr_reserve_space(&sctxt->sc_stream, 938 rpcrdma_fixed_maxsz * sizeof(*p)); 939 if (!p) 940 goto put_ctxt; 941 942 *p++ = *rdma_argp; 943 *p++ = *(rdma_argp + 1); 944 *p++ = rdma->sc_fc_credits; 945 *p = rdma_error; 946 947 switch (status) { 948 case -EPROTONOSUPPORT: 949 p = xdr_reserve_space(&sctxt->sc_stream, 3 * sizeof(*p)); 950 if (!p) 951 goto put_ctxt; 952 953 *p++ = err_vers; 954 *p++ = rpcrdma_version; 955 *p = rpcrdma_version; 956 trace_svcrdma_err_vers(*rdma_argp); 957 break; 958 default: 959 p = xdr_reserve_space(&sctxt->sc_stream, sizeof(*p)); 960 if (!p) 961 goto put_ctxt; 962 963 *p = err_chunk; 964 trace_svcrdma_err_chunk(*rdma_argp); 965 } 966 967 /* Remote Invalidation is skipped for simplicity. */ 968 sctxt->sc_send_wr.num_sge = 1; 969 sctxt->sc_send_wr.opcode = IB_WR_SEND; 970 sctxt->sc_sges[0].length = sctxt->sc_hdrbuf.len; 971 if (svc_rdma_post_send(rdma, sctxt)) 972 goto put_ctxt; 973 return; 974 975 put_ctxt: 976 svc_rdma_send_ctxt_put(rdma, sctxt); 977 } 978 979 /** 980 * svc_rdma_sendto - Transmit an RPC reply 981 * @rqstp: processed RPC request, reply XDR already in ::rq_res 982 * 983 * Any resources still associated with @rqstp are released upon return. 984 * If no reply message was possible, the connection is closed. 985 * 986 * Returns: 987 * %0 if an RPC reply has been successfully posted, 988 * %-ENOMEM if a resource shortage occurred (connection is lost), 989 * %-ENOTCONN if posting failed (connection is lost). 990 */ 991 int svc_rdma_sendto(struct svc_rqst *rqstp) 992 { 993 struct svc_xprt *xprt = rqstp->rq_xprt; 994 struct svcxprt_rdma *rdma = 995 container_of(xprt, struct svcxprt_rdma, sc_xprt); 996 struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt; 997 __be32 *rdma_argp = rctxt->rc_recv_buf; 998 struct svc_rdma_send_ctxt *sctxt; 999 unsigned int rc_size; 1000 __be32 *p; 1001 int ret; 1002 1003 ret = -ENOTCONN; 1004 if (svc_xprt_is_dead(xprt)) 1005 goto drop_connection; 1006 1007 ret = -ENOMEM; 1008 sctxt = svc_rdma_send_ctxt_get(rdma); 1009 if (!sctxt) 1010 goto drop_connection; 1011 1012 ret = -EMSGSIZE; 1013 p = xdr_reserve_space(&sctxt->sc_stream, 1014 rpcrdma_fixed_maxsz * sizeof(*p)); 1015 if (!p) 1016 goto put_ctxt; 1017 1018 ret = svc_rdma_prepare_write_list(rdma, &rctxt->rc_write_pcl, sctxt, 1019 &rqstp->rq_res); 1020 if (ret < 0) 1021 goto put_ctxt; 1022 1023 rc_size = 0; 1024 if (!pcl_is_empty(&rctxt->rc_reply_pcl)) { 1025 ret = svc_rdma_prepare_reply_chunk(rdma, &rctxt->rc_write_pcl, 1026 &rctxt->rc_reply_pcl, sctxt, 1027 &rqstp->rq_res); 1028 if (ret < 0) 1029 goto reply_chunk; 1030 rc_size = ret; 1031 } 1032 1033 *p++ = *rdma_argp; 1034 *p++ = *(rdma_argp + 1); 1035 *p++ = rdma->sc_fc_credits; 1036 *p = pcl_is_empty(&rctxt->rc_reply_pcl) ? rdma_msg : rdma_nomsg; 1037 1038 ret = svc_rdma_encode_read_list(sctxt); 1039 if (ret < 0) 1040 goto put_ctxt; 1041 ret = svc_rdma_encode_write_list(rctxt, sctxt); 1042 if (ret < 0) 1043 goto put_ctxt; 1044 ret = svc_rdma_encode_reply_chunk(rctxt, sctxt, rc_size); 1045 if (ret < 0) 1046 goto put_ctxt; 1047 1048 ret = svc_rdma_send_reply_msg(rdma, sctxt, rctxt, rqstp); 1049 if (ret < 0) 1050 goto put_ctxt; 1051 return 0; 1052 1053 reply_chunk: 1054 if (ret != -E2BIG && ret != -EINVAL) 1055 goto put_ctxt; 1056 1057 /* Send completion releases payload pages that were part 1058 * of previously posted RDMA Writes. 1059 */ 1060 svc_rdma_save_io_pages(rqstp, sctxt); 1061 svc_rdma_send_error_msg(rdma, sctxt, rctxt, ret); 1062 return 0; 1063 1064 put_ctxt: 1065 svc_rdma_send_ctxt_put(rdma, sctxt); 1066 drop_connection: 1067 trace_svcrdma_send_err(rqstp, ret); 1068 svc_xprt_deferred_close(&rdma->sc_xprt); 1069 return -ENOTCONN; 1070 } 1071 1072 /** 1073 * svc_rdma_result_payload - special processing for a result payload 1074 * @rqstp: RPC transaction context 1075 * @offset: payload's byte offset in @rqstp->rq_res 1076 * @length: size of payload, in bytes 1077 * 1078 * Assign the passed-in result payload to the current Write chunk, 1079 * and advance to cur_result_payload to the next Write chunk, if 1080 * there is one. 1081 * 1082 * Return values: 1083 * %0 if successful or nothing needed to be done 1084 * %-E2BIG if the payload was larger than the Write chunk 1085 */ 1086 int svc_rdma_result_payload(struct svc_rqst *rqstp, unsigned int offset, 1087 unsigned int length) 1088 { 1089 struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt; 1090 struct svc_rdma_chunk *chunk; 1091 1092 chunk = rctxt->rc_cur_result_payload; 1093 if (!length || !chunk) 1094 return 0; 1095 rctxt->rc_cur_result_payload = 1096 pcl_next_chunk(&rctxt->rc_write_pcl, chunk); 1097 1098 if (length > chunk->ch_length) 1099 return -E2BIG; 1100 chunk->ch_position = offset; 1101 chunk->ch_payload_length = length; 1102 return 0; 1103 } 1104