rpc_rdma.c

   1// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
   2/*
   3 * Copyright (c) 2014-2020, Oracle and/or its affiliates.
   4 * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
   5 *
   6 * This software is available to you under a choice of one of two
   7 * licenses.  You may choose to be licensed under the terms of the GNU
   8 * General Public License (GPL) Version 2, available from the file
   9 * COPYING in the main directory of this source tree, or the BSD-type
  10 * license below:
  11 *
  12 * Redistribution and use in source and binary forms, with or without
  13 * modification, are permitted provided that the following conditions
  14 * are met:
  15 *
  16 *      Redistributions of source code must retain the above copyright
  17 *      notice, this list of conditions and the following disclaimer.
  18 *
  19 *      Redistributions in binary form must reproduce the above
  20 *      copyright notice, this list of conditions and the following
  21 *      disclaimer in the documentation and/or other materials provided
  22 *      with the distribution.
  23 *
  24 *      Neither the name of the Network Appliance, Inc. nor the names of
  25 *      its contributors may be used to endorse or promote products
  26 *      derived from this software without specific prior written
  27 *      permission.
  28 *
  29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  33 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  34 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  35 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  39 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  40 */
  41
  42/*
  43 * rpc_rdma.c
  44 *
  45 * This file contains the guts of the RPC RDMA protocol, and
  46 * does marshaling/unmarshaling, etc. It is also where interfacing
  47 * to the Linux RPC framework lives.
  48 */
  49
  50#include <linux/highmem.h>
  51
  52#include <linux/sunrpc/svc_rdma.h>
  53
  54#include "xprt_rdma.h"
  55#include <trace/events/rpcrdma.h>
  56
  57/* Returns size of largest RPC-over-RDMA header in a Call message
  58 *
  59 * The largest Call header contains a full-size Read list and a
  60 * minimal Reply chunk.
  61 */
  62static unsigned int rpcrdma_max_call_header_size(unsigned int maxsegs)
  63{
  64	unsigned int size;
  65
  66	/* Fixed header fields and list discriminators */
  67	size = RPCRDMA_HDRLEN_MIN;
  68
  69	/* Maximum Read list size */
  70	size += maxsegs * rpcrdma_readchunk_maxsz * sizeof(__be32);
  71
  72	/* Minimal Read chunk size */
  73	size += sizeof(__be32);	/* segment count */
  74	size += rpcrdma_segment_maxsz * sizeof(__be32);
  75	size += sizeof(__be32);	/* list discriminator */
  76
  77	return size;
  78}
  79
  80/* Returns size of largest RPC-over-RDMA header in a Reply message
  81 *
  82 * There is only one Write list or one Reply chunk per Reply
  83 * message.  The larger list is the Write list.
  84 */
  85static unsigned int rpcrdma_max_reply_header_size(unsigned int maxsegs)
  86{
  87	unsigned int size;
  88
  89	/* Fixed header fields and list discriminators */
  90	size = RPCRDMA_HDRLEN_MIN;
  91
  92	/* Maximum Write list size */
  93	size += sizeof(__be32);		/* segment count */
  94	size += maxsegs * rpcrdma_segment_maxsz * sizeof(__be32);
  95	size += sizeof(__be32);	/* list discriminator */
  96
  97	return size;
  98}
  99
 100/**
 101 * rpcrdma_set_max_header_sizes - Initialize inline payload sizes
 102 * @ep: endpoint to initialize
 103 *
 104 * The max_inline fields contain the maximum size of an RPC message
 105 * so the marshaling code doesn't have to repeat this calculation
 106 * for every RPC.
 107 */
 108void rpcrdma_set_max_header_sizes(struct rpcrdma_ep *ep)
 109{
 110	unsigned int maxsegs = ep->re_max_rdma_segs;
 111
 112	ep->re_max_inline_send =
 113		ep->re_inline_send - rpcrdma_max_call_header_size(maxsegs);
 114	ep->re_max_inline_recv =
 115		ep->re_inline_recv - rpcrdma_max_reply_header_size(maxsegs);
 116}
 117
 118/* The client can send a request inline as long as the RPCRDMA header
 119 * plus the RPC call fit under the transport's inline limit. If the
 120 * combined call message size exceeds that limit, the client must use
 121 * a Read chunk for this operation.
 122 *
 123 * A Read chunk is also required if sending the RPC call inline would
 124 * exceed this device's max_sge limit.
 125 */
 126static bool rpcrdma_args_inline(struct rpcrdma_xprt *r_xprt,
 127				struct rpc_rqst *rqst)
 128{
 129	struct xdr_buf *xdr = &rqst->rq_snd_buf;
 130	struct rpcrdma_ep *ep = r_xprt->rx_ep;
 131	unsigned int count, remaining, offset;
 132
 133	if (xdr->len > ep->re_max_inline_send)
 134		return false;
 135
 136	if (xdr->page_len) {
 137		remaining = xdr->page_len;
 138		offset = offset_in_page(xdr->page_base);
 139		count = RPCRDMA_MIN_SEND_SGES;
 140		while (remaining) {
 141			remaining -= min_t(unsigned int,
 142					   PAGE_SIZE - offset, remaining);
 143			offset = 0;
 144			if (++count > ep->re_attr.cap.max_send_sge)
 145				return false;
 146		}
 147	}
 148
 149	return true;
 150}
 151
 152/* The client can't know how large the actual reply will be. Thus it
 153 * plans for the largest possible reply for that particular ULP
 154 * operation. If the maximum combined reply message size exceeds that
 155 * limit, the client must provide a write list or a reply chunk for
 156 * this request.
 157 */
 158static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
 159				   struct rpc_rqst *rqst)
 160{
 161	return rqst->rq_rcv_buf.buflen <= r_xprt->rx_ep->re_max_inline_recv;
 162}
 163
 164/* The client is required to provide a Reply chunk if the maximum
 165 * size of the non-payload part of the RPC Reply is larger than
 166 * the inline threshold.
 167 */
 168static bool
 169rpcrdma_nonpayload_inline(const struct rpcrdma_xprt *r_xprt,
 170			  const struct rpc_rqst *rqst)
 171{
 172	const struct xdr_buf *buf = &rqst->rq_rcv_buf;
 173
 174	return (buf->head[0].iov_len + buf->tail[0].iov_len) <
 175		r_xprt->rx_ep->re_max_inline_recv;
 176}
 177
 178/* ACL likes to be lazy in allocating pages. For TCP, these
 179 * pages can be allocated during receive processing. Not true
 180 * for RDMA, which must always provision receive buffers
 181 * up front.
 182 */
 183static noinline int
 184rpcrdma_alloc_sparse_pages(struct xdr_buf *buf)
 185{
 186	struct page **ppages;
 187	int len;
 188
 189	len = buf->page_len;
 190	ppages = buf->pages + (buf->page_base >> PAGE_SHIFT);
 191	while (len > 0) {
 192		if (!*ppages)
 193			*ppages = alloc_page(GFP_NOWAIT);
 194		if (!*ppages)
 195			return -ENOBUFS;
 196		ppages++;
 197		len -= PAGE_SIZE;
 198	}
 199
 200	return 0;
 201}
 202
 203/* Convert @vec to a single SGL element.
 204 *
 205 * Returns pointer to next available SGE, and bumps the total number
 206 * of SGEs consumed.
 207 */
 208static struct rpcrdma_mr_seg *
 209rpcrdma_convert_kvec(struct kvec *vec, struct rpcrdma_mr_seg *seg,
 210		     unsigned int *n)
 211{
 212	seg->mr_page = virt_to_page(vec->iov_base);
 213	seg->mr_offset = offset_in_page(vec->iov_base);
 214	seg->mr_len = vec->iov_len;
 215	++seg;
 216	++(*n);
 217	return seg;
 218}
 219
 220/* Convert @xdrbuf into SGEs no larger than a page each. As they
 221 * are registered, these SGEs are then coalesced into RDMA segments
 222 * when the selected memreg mode supports it.
 223 *
 224 * Returns positive number of SGEs consumed, or a negative errno.
 225 */
 226
 227static int
 228rpcrdma_convert_iovs(struct rpcrdma_xprt *r_xprt, struct xdr_buf *xdrbuf,
 229		     unsigned int pos, enum rpcrdma_chunktype type,
 230		     struct rpcrdma_mr_seg *seg)
 231{
 232	unsigned long page_base;
 233	unsigned int len, n;
 234	struct page **ppages;
 235
 236	n = 0;
 237	if (pos == 0)
 238		seg = rpcrdma_convert_kvec(&xdrbuf->head[0], seg, &n);
 239
 240	len = xdrbuf->page_len;
 241	ppages = xdrbuf->pages + (xdrbuf->page_base >> PAGE_SHIFT);
 242	page_base = offset_in_page(xdrbuf->page_base);
 243	while (len) {
 244		seg->mr_page = *ppages;
 245		seg->mr_offset = page_base;
 246		seg->mr_len = min_t(u32, PAGE_SIZE - page_base, len);
 247		len -= seg->mr_len;
 248		++ppages;
 249		++seg;
 250		++n;
 251		page_base = 0;
 252	}
 253
 254	if (type == rpcrdma_readch || type == rpcrdma_writech)
 255		goto out;
 256
 257	if (xdrbuf->tail[0].iov_len)
 258		rpcrdma_convert_kvec(&xdrbuf->tail[0], seg, &n);
 259
 260out:
 261	if (unlikely(n > RPCRDMA_MAX_SEGS))
 262		return -EIO;
 263	return n;
 264}
 265
 266static int
 267encode_rdma_segment(struct xdr_stream *xdr, struct rpcrdma_mr *mr)
 268{
 269	__be32 *p;
 270
 271	p = xdr_reserve_space(xdr, 4 * sizeof(*p));
 272	if (unlikely(!p))
 273		return -EMSGSIZE;
 274
 275	xdr_encode_rdma_segment(p, mr->mr_handle, mr->mr_length, mr->mr_offset);
 276	return 0;
 277}
 278
 279static int
 280encode_read_segment(struct xdr_stream *xdr, struct rpcrdma_mr *mr,
 281		    u32 position)
 282{
 283	__be32 *p;
 284
 285	p = xdr_reserve_space(xdr, 6 * sizeof(*p));
 286	if (unlikely(!p))
 287		return -EMSGSIZE;
 288
 289	*p++ = xdr_one;			/* Item present */
 290	xdr_encode_read_segment(p, position, mr->mr_handle, mr->mr_length,
 291				mr->mr_offset);
 292	return 0;
 293}
 294
 295static struct rpcrdma_mr_seg *rpcrdma_mr_prepare(struct rpcrdma_xprt *r_xprt,
 296						 struct rpcrdma_req *req,
 297						 struct rpcrdma_mr_seg *seg,
 298						 int nsegs, bool writing,
 299						 struct rpcrdma_mr **mr)
 300{
 301	*mr = rpcrdma_mr_pop(&req->rl_free_mrs);
 302	if (!*mr) {
 303		*mr = rpcrdma_mr_get(r_xprt);
 304		if (!*mr)
 305			goto out_getmr_err;
 306		(*mr)->mr_req = req;
 307	}
 308
 309	rpcrdma_mr_push(*mr, &req->rl_registered);
 310	return frwr_map(r_xprt, seg, nsegs, writing, req->rl_slot.rq_xid, *mr);
 311
 312out_getmr_err:
 313	trace_xprtrdma_nomrs_err(r_xprt, req);
 314	xprt_wait_for_buffer_space(&r_xprt->rx_xprt);
 315	rpcrdma_mrs_refresh(r_xprt);
 316	return ERR_PTR(-EAGAIN);
 317}
 318
 319/* Register and XDR encode the Read list. Supports encoding a list of read
 320 * segments that belong to a single read chunk.
 321 *
 322 * Encoding key for single-list chunks (HLOO = Handle32 Length32 Offset64):
 323 *
 324 *  Read chunklist (a linked list):
 325 *   N elements, position P (same P for all chunks of same arg!):
 326 *    1 - PHLOO - 1 - PHLOO - ... - 1 - PHLOO - 0
 327 *
 328 * Returns zero on success, or a negative errno if a failure occurred.
 329 * @xdr is advanced to the next position in the stream.
 330 *
 331 * Only a single @pos value is currently supported.
 332 */
 333static int rpcrdma_encode_read_list(struct rpcrdma_xprt *r_xprt,
 334				    struct rpcrdma_req *req,
 335				    struct rpc_rqst *rqst,
 336				    enum rpcrdma_chunktype rtype)
 337{
 338	struct xdr_stream *xdr = &req->rl_stream;
 339	struct rpcrdma_mr_seg *seg;
 340	struct rpcrdma_mr *mr;
 341	unsigned int pos;
 342	int nsegs;
 343
 344	if (rtype == rpcrdma_noch_pullup || rtype == rpcrdma_noch_mapped)
 345		goto done;
 346
 347	pos = rqst->rq_snd_buf.head[0].iov_len;
 348	if (rtype == rpcrdma_areadch)
 349		pos = 0;
 350	seg = req->rl_segments;
 351	nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_snd_buf, pos,
 352				     rtype, seg);
 353	if (nsegs < 0)
 354		return nsegs;
 355
 356	do {
 357		seg = rpcrdma_mr_prepare(r_xprt, req, seg, nsegs, false, &mr);
 358		if (IS_ERR(seg))
 359			return PTR_ERR(seg);
 360
 361		if (encode_read_segment(xdr, mr, pos) < 0)
 362			return -EMSGSIZE;
 363
 364		trace_xprtrdma_chunk_read(rqst->rq_task, pos, mr, nsegs);
 365		r_xprt->rx_stats.read_chunk_count++;
 366		nsegs -= mr->mr_nents;
 367	} while (nsegs);
 368
 369done:
 370	if (xdr_stream_encode_item_absent(xdr) < 0)
 371		return -EMSGSIZE;
 372	return 0;
 373}
 374
 375/* Register and XDR encode the Write list. Supports encoding a list
 376 * containing one array of plain segments that belong to a single
 377 * write chunk.
 378 *
 379 * Encoding key for single-list chunks (HLOO = Handle32 Length32 Offset64):
 380 *
 381 *  Write chunklist (a list of (one) counted array):
 382 *   N elements:
 383 *    1 - N - HLOO - HLOO - ... - HLOO - 0
 384 *
 385 * Returns zero on success, or a negative errno if a failure occurred.
 386 * @xdr is advanced to the next position in the stream.
 387 *
 388 * Only a single Write chunk is currently supported.
 389 */
 390static int rpcrdma_encode_write_list(struct rpcrdma_xprt *r_xprt,
 391				     struct rpcrdma_req *req,
 392				     struct rpc_rqst *rqst,
 393				     enum rpcrdma_chunktype wtype)
 394{
 395	struct xdr_stream *xdr = &req->rl_stream;
 396	struct rpcrdma_ep *ep = r_xprt->rx_ep;
 397	struct rpcrdma_mr_seg *seg;
 398	struct rpcrdma_mr *mr;
 399	int nsegs, nchunks;
 400	__be32 *segcount;
 401
 402	if (wtype != rpcrdma_writech)
 403		goto done;
 404
 405	seg = req->rl_segments;
 406	nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_rcv_buf,
 407				     rqst->rq_rcv_buf.head[0].iov_len,
 408				     wtype, seg);
 409	if (nsegs < 0)
 410		return nsegs;
 411
 412	if (xdr_stream_encode_item_present(xdr) < 0)
 413		return -EMSGSIZE;
 414	segcount = xdr_reserve_space(xdr, sizeof(*segcount));
 415	if (unlikely(!segcount))
 416		return -EMSGSIZE;
 417	/* Actual value encoded below */
 418
 419	nchunks = 0;
 420	do {
 421		seg = rpcrdma_mr_prepare(r_xprt, req, seg, nsegs, true, &mr);
 422		if (IS_ERR(seg))
 423			return PTR_ERR(seg);
 424
 425		if (encode_rdma_segment(xdr, mr) < 0)
 426			return -EMSGSIZE;
 427
 428		trace_xprtrdma_chunk_write(rqst->rq_task, mr, nsegs);
 429		r_xprt->rx_stats.write_chunk_count++;
 430		r_xprt->rx_stats.total_rdma_request += mr->mr_length;
 431		nchunks++;
 432		nsegs -= mr->mr_nents;
 433	} while (nsegs);
 434
 435	if (xdr_pad_size(rqst->rq_rcv_buf.page_len)) {
 436		if (encode_rdma_segment(xdr, ep->re_write_pad_mr) < 0)
 437			return -EMSGSIZE;
 438
 439		trace_xprtrdma_chunk_wp(rqst->rq_task, ep->re_write_pad_mr,
 440					nsegs);
 441		r_xprt->rx_stats.write_chunk_count++;
 442		r_xprt->rx_stats.total_rdma_request += mr->mr_length;
 443		nchunks++;
 444		nsegs -= mr->mr_nents;
 445	}
 446
 447	/* Update count of segments in this Write chunk */
 448	*segcount = cpu_to_be32(nchunks);
 449
 450done:
 451	if (xdr_stream_encode_item_absent(xdr) < 0)
 452		return -EMSGSIZE;
 453	return 0;
 454}
 455
 456/* Register and XDR encode the Reply chunk. Supports encoding an array
 457 * of plain segments that belong to a single write (reply) chunk.
 458 *
 459 * Encoding key for single-list chunks (HLOO = Handle32 Length32 Offset64):
 460 *
 461 *  Reply chunk (a counted array):
 462 *   N elements:
 463 *    1 - N - HLOO - HLOO - ... - HLOO
 464 *
 465 * Returns zero on success, or a negative errno if a failure occurred.
 466 * @xdr is advanced to the next position in the stream.
 467 */
 468static int rpcrdma_encode_reply_chunk(struct rpcrdma_xprt *r_xprt,
 469				      struct rpcrdma_req *req,
 470				      struct rpc_rqst *rqst,
 471				      enum rpcrdma_chunktype wtype)
 472{
 473	struct xdr_stream *xdr = &req->rl_stream;
 474	struct rpcrdma_mr_seg *seg;
 475	struct rpcrdma_mr *mr;
 476	int nsegs, nchunks;
 477	__be32 *segcount;
 478
 479	if (wtype != rpcrdma_replych) {
 480		if (xdr_stream_encode_item_absent(xdr) < 0)
 481			return -EMSGSIZE;
 482		return 0;
 483	}
 484
 485	seg = req->rl_segments;
 486	nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_rcv_buf, 0, wtype, seg);
 487	if (nsegs < 0)
 488		return nsegs;
 489
 490	if (xdr_stream_encode_item_present(xdr) < 0)
 491		return -EMSGSIZE;
 492	segcount = xdr_reserve_space(xdr, sizeof(*segcount));
 493	if (unlikely(!segcount))
 494		return -EMSGSIZE;
 495	/* Actual value encoded below */
 496
 497	nchunks = 0;
 498	do {
 499		seg = rpcrdma_mr_prepare(r_xprt, req, seg, nsegs, true, &mr);
 500		if (IS_ERR(seg))
 501			return PTR_ERR(seg);
 502
 503		if (encode_rdma_segment(xdr, mr) < 0)
 504			return -EMSGSIZE;
 505
 506		trace_xprtrdma_chunk_reply(rqst->rq_task, mr, nsegs);
 507		r_xprt->rx_stats.reply_chunk_count++;
 508		r_xprt->rx_stats.total_rdma_request += mr->mr_length;
 509		nchunks++;
 510		nsegs -= mr->mr_nents;
 511	} while (nsegs);
 512
 513	/* Update count of segments in the Reply chunk */
 514	*segcount = cpu_to_be32(nchunks);
 515
 516	return 0;
 517}
 518
 519static void rpcrdma_sendctx_done(struct kref *kref)
 520{
 521	struct rpcrdma_req *req =
 522		container_of(kref, struct rpcrdma_req, rl_kref);
 523	struct rpcrdma_rep *rep = req->rl_reply;
 524
 525	rpcrdma_complete_rqst(rep);
 526	rep->rr_rxprt->rx_stats.reply_waits_for_send++;
 527}
 528
 529/**
 530 * rpcrdma_sendctx_unmap - DMA-unmap Send buffer
 531 * @sc: sendctx containing SGEs to unmap
 532 *
 533 */
 534void rpcrdma_sendctx_unmap(struct rpcrdma_sendctx *sc)
 535{
 536	struct rpcrdma_regbuf *rb = sc->sc_req->rl_sendbuf;
 537	struct ib_sge *sge;
 538
 539	if (!sc->sc_unmap_count)
 540		return;
 541
 542	/* The first two SGEs contain the transport header and
 543	 * the inline buffer. These are always left mapped so
 544	 * they can be cheaply re-used.
 545	 */
 546	for (sge = &sc->sc_sges[2]; sc->sc_unmap_count;
 547	     ++sge, --sc->sc_unmap_count)
 548		ib_dma_unmap_page(rdmab_device(rb), sge->addr, sge->length,
 549				  DMA_TO_DEVICE);
 550
 551	kref_put(&sc->sc_req->rl_kref, rpcrdma_sendctx_done);
 552}
 553
 554/* Prepare an SGE for the RPC-over-RDMA transport header.
 555 */
 556static void rpcrdma_prepare_hdr_sge(struct rpcrdma_xprt *r_xprt,
 557				    struct rpcrdma_req *req, u32 len)
 558{
 559	struct rpcrdma_sendctx *sc = req->rl_sendctx;
 560	struct rpcrdma_regbuf *rb = req->rl_rdmabuf;
 561	struct ib_sge *sge = &sc->sc_sges[req->rl_wr.num_sge++];
 562
 563	sge->addr = rdmab_addr(rb);
 564	sge->length = len;
 565	sge->lkey = rdmab_lkey(rb);
 566
 567	ib_dma_sync_single_for_device(rdmab_device(rb), sge->addr, sge->length,
 568				      DMA_TO_DEVICE);
 569}
 570
 571/* The head iovec is straightforward, as it is usually already
 572 * DMA-mapped. Sync the content that has changed.
 573 */
 574static bool rpcrdma_prepare_head_iov(struct rpcrdma_xprt *r_xprt,
 575				     struct rpcrdma_req *req, unsigned int len)
 576{
 577	struct rpcrdma_sendctx *sc = req->rl_sendctx;
 578	struct ib_sge *sge = &sc->sc_sges[req->rl_wr.num_sge++];
 579	struct rpcrdma_regbuf *rb = req->rl_sendbuf;
 580
 581	if (!rpcrdma_regbuf_dma_map(r_xprt, rb))
 582		return false;
 583
 584	sge->addr = rdmab_addr(rb);
 585	sge->length = len;
 586	sge->lkey = rdmab_lkey(rb);
 587
 588	ib_dma_sync_single_for_device(rdmab_device(rb), sge->addr, sge->length,
 589				      DMA_TO_DEVICE);
 590	return true;
 591}
 592
 593/* If there is a page list present, DMA map and prepare an
 594 * SGE for each page to be sent.
 595 */
 596static bool rpcrdma_prepare_pagelist(struct rpcrdma_req *req,
 597				     struct xdr_buf *xdr)
 598{
 599	struct rpcrdma_sendctx *sc = req->rl_sendctx;
 600	struct rpcrdma_regbuf *rb = req->rl_sendbuf;
 601	unsigned int page_base, len, remaining;
 602	struct page **ppages;
 603	struct ib_sge *sge;
 604
 605	ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
 606	page_base = offset_in_page(xdr->page_base);
 607	remaining = xdr->page_len;
 608	while (remaining) {
 609		sge = &sc->sc_sges[req->rl_wr.num_sge++];
 610		len = min_t(unsigned int, PAGE_SIZE - page_base, remaining);
 611		sge->addr = ib_dma_map_page(rdmab_device(rb), *ppages,
 612					    page_base, len, DMA_TO_DEVICE);
 613		if (ib_dma_mapping_error(rdmab_device(rb), sge->addr))
 614			goto out_mapping_err;
 615
 616		sge->length = len;
 617		sge->lkey = rdmab_lkey(rb);
 618
 619		sc->sc_unmap_count++;
 620		ppages++;
 621		remaining -= len;
 622		page_base = 0;
 623	}
 624
 625	return true;
 626
 627out_mapping_err:
 628	trace_xprtrdma_dma_maperr(sge->addr);
 629	return false;
 630}
 631
 632/* The tail iovec may include an XDR pad for the page list,
 633 * as well as additional content, and may not reside in the
 634 * same page as the head iovec.
 635 */
 636static bool rpcrdma_prepare_tail_iov(struct rpcrdma_req *req,
 637				     struct xdr_buf *xdr,
 638				     unsigned int page_base, unsigned int len)
 639{
 640	struct rpcrdma_sendctx *sc = req->rl_sendctx;
 641	struct ib_sge *sge = &sc->sc_sges[req->rl_wr.num_sge++];
 642	struct rpcrdma_regbuf *rb = req->rl_sendbuf;
 643	struct page *page = virt_to_page(xdr->tail[0].iov_base);
 644
 645	sge->addr = ib_dma_map_page(rdmab_device(rb), page, page_base, len,
 646				    DMA_TO_DEVICE);
 647	if (ib_dma_mapping_error(rdmab_device(rb), sge->addr))
 648		goto out_mapping_err;
 649
 650	sge->length = len;
 651	sge->lkey = rdmab_lkey(rb);
 652	++sc->sc_unmap_count;
 653	return true;
 654
 655out_mapping_err:
 656	trace_xprtrdma_dma_maperr(sge->addr);
 657	return false;
 658}
 659
 660/* Copy the tail to the end of the head buffer.
 661 */
 662static void rpcrdma_pullup_tail_iov(struct rpcrdma_xprt *r_xprt,
 663				    struct rpcrdma_req *req,
 664				    struct xdr_buf *xdr)
 665{
 666	unsigned char *dst;
 667
 668	dst = (unsigned char *)xdr->head[0].iov_base;
 669	dst += xdr->head[0].iov_len + xdr->page_len;
 670	memmove(dst, xdr->tail[0].iov_base, xdr->tail[0].iov_len);
 671	r_xprt->rx_stats.pullup_copy_count += xdr->tail[0].iov_len;
 672}
 673
 674/* Copy pagelist content into the head buffer.
 675 */
 676static void rpcrdma_pullup_pagelist(struct rpcrdma_xprt *r_xprt,
 677				    struct rpcrdma_req *req,
 678				    struct xdr_buf *xdr)
 679{
 680	unsigned int len, page_base, remaining;
 681	struct page **ppages;
 682	unsigned char *src, *dst;
 683
 684	dst = (unsigned char *)xdr->head[0].iov_base;
 685	dst += xdr->head[0].iov_len;
 686	ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
 687	page_base = offset_in_page(xdr->page_base);
 688	remaining = xdr->page_len;
 689	while (remaining) {
 690		src = page_address(*ppages);
 691		src += page_base;
 692		len = min_t(unsigned int, PAGE_SIZE - page_base, remaining);
 693		memcpy(dst, src, len);
 694		r_xprt->rx_stats.pullup_copy_count += len;
 695
 696		ppages++;
 697		dst += len;
 698		remaining -= len;
 699		page_base = 0;
 700	}
 701}
 702
 703/* Copy the contents of @xdr into @rl_sendbuf and DMA sync it.
 704 * When the head, pagelist, and tail are small, a pull-up copy
 705 * is considerably less costly than DMA mapping the components
 706 * of @xdr.
 707 *
 708 * Assumptions:
 709 *  - the caller has already verified that the total length
 710 *    of the RPC Call body will fit into @rl_sendbuf.
 711 */
 712static bool rpcrdma_prepare_noch_pullup(struct rpcrdma_xprt *r_xprt,
 713					struct rpcrdma_req *req,
 714					struct xdr_buf *xdr)
 715{
 716	if (unlikely(xdr->tail[0].iov_len))
 717		rpcrdma_pullup_tail_iov(r_xprt, req, xdr);
 718
 719	if (unlikely(xdr->page_len))
 720		rpcrdma_pullup_pagelist(r_xprt, req, xdr);
 721
 722	/* The whole RPC message resides in the head iovec now */
 723	return rpcrdma_prepare_head_iov(r_xprt, req, xdr->len);
 724}
 725
 726static bool rpcrdma_prepare_noch_mapped(struct rpcrdma_xprt *r_xprt,
 727					struct rpcrdma_req *req,
 728					struct xdr_buf *xdr)
 729{
 730	struct kvec *tail = &xdr->tail[0];
 731
 732	if (!rpcrdma_prepare_head_iov(r_xprt, req, xdr->head[0].iov_len))
 733		return false;
 734	if (xdr->page_len)
 735		if (!rpcrdma_prepare_pagelist(req, xdr))
 736			return false;
 737	if (tail->iov_len)
 738		if (!rpcrdma_prepare_tail_iov(req, xdr,
 739					      offset_in_page(tail->iov_base),
 740					      tail->iov_len))
 741			return false;
 742
 743	if (req->rl_sendctx->sc_unmap_count)
 744		kref_get(&req->rl_kref);
 745	return true;
 746}
 747
 748static bool rpcrdma_prepare_readch(struct rpcrdma_xprt *r_xprt,
 749				   struct rpcrdma_req *req,
 750				   struct xdr_buf *xdr)
 751{
 752	if (!rpcrdma_prepare_head_iov(r_xprt, req, xdr->head[0].iov_len))
 753		return false;
 754
 755	/* If there is a Read chunk, the page list is being handled
 756	 * via explicit RDMA, and thus is skipped here.
 757	 */
 758
 759	/* Do not include the tail if it is only an XDR pad */
 760	if (xdr->tail[0].iov_len > 3) {
 761		unsigned int page_base, len;
 762
 763		/* If the content in the page list is an odd length,
 764		 * xdr_write_pages() adds a pad at the beginning of
 765		 * the tail iovec. Force the tail's non-pad content to
 766		 * land at the next XDR position in the Send message.
 767		 */
 768		page_base = offset_in_page(xdr->tail[0].iov_base);
 769		len = xdr->tail[0].iov_len;
 770		page_base += len & 3;
 771		len -= len & 3;
 772		if (!rpcrdma_prepare_tail_iov(req, xdr, page_base, len))
 773			return false;
 774		kref_get(&req->rl_kref);
 775	}
 776
 777	return true;
 778}
 779
 780/**
 781 * rpcrdma_prepare_send_sges - Construct SGEs for a Send WR
 782 * @r_xprt: controlling transport
 783 * @req: context of RPC Call being marshalled
 784 * @hdrlen: size of transport header, in bytes
 785 * @xdr: xdr_buf containing RPC Call
 786 * @rtype: chunk type being encoded
 787 *
 788 * Returns 0 on success; otherwise a negative errno is returned.
 789 */
 790inline int rpcrdma_prepare_send_sges(struct rpcrdma_xprt *r_xprt,
 791				     struct rpcrdma_req *req, u32 hdrlen,
 792				     struct xdr_buf *xdr,
 793				     enum rpcrdma_chunktype rtype)
 794{
 795	int ret;
 796
 797	ret = -EAGAIN;
 798	req->rl_sendctx = rpcrdma_sendctx_get_locked(r_xprt);
 799	if (!req->rl_sendctx)
 800		goto out_nosc;
 801	req->rl_sendctx->sc_unmap_count = 0;
 802	req->rl_sendctx->sc_req = req;
 803	kref_init(&req->rl_kref);
 804	req->rl_wr.wr_cqe = &req->rl_sendctx->sc_cqe;
 805	req->rl_wr.sg_list = req->rl_sendctx->sc_sges;
 806	req->rl_wr.num_sge = 0;
 807	req->rl_wr.opcode = IB_WR_SEND;
 808
 809	rpcrdma_prepare_hdr_sge(r_xprt, req, hdrlen);
 810
 811	ret = -EIO;
 812	switch (rtype) {
 813	case rpcrdma_noch_pullup:
 814		if (!rpcrdma_prepare_noch_pullup(r_xprt, req, xdr))
 815			goto out_unmap;
 816		break;
 817	case rpcrdma_noch_mapped:
 818		if (!rpcrdma_prepare_noch_mapped(r_xprt, req, xdr))
 819			goto out_unmap;
 820		break;
 821	case rpcrdma_readch:
 822		if (!rpcrdma_prepare_readch(r_xprt, req, xdr))
 823			goto out_unmap;
 824		break;
 825	case rpcrdma_areadch:
 826		break;
 827	default:
 828		goto out_unmap;
 829	}
 830
 831	return 0;
 832
 833out_unmap:
 834	rpcrdma_sendctx_unmap(req->rl_sendctx);
 835out_nosc:
 836	trace_xprtrdma_prepsend_failed(&req->rl_slot, ret);
 837	return ret;
 838}
 839
 840/**
 841 * rpcrdma_marshal_req - Marshal and send one RPC request
 842 * @r_xprt: controlling transport
 843 * @rqst: RPC request to be marshaled
 844 *
 845 * For the RPC in "rqst", this function:
 846 *  - Chooses the transfer mode (eg., RDMA_MSG or RDMA_NOMSG)
 847 *  - Registers Read, Write, and Reply chunks
 848 *  - Constructs the transport header
 849 *  - Posts a Send WR to send the transport header and request
 850 *
 851 * Returns:
 852 *	%0 if the RPC was sent successfully,
 853 *	%-ENOTCONN if the connection was lost,
 854 *	%-EAGAIN if the caller should call again with the same arguments,
 855 *	%-ENOBUFS if the caller should call again after a delay,
 856 *	%-EMSGSIZE if the transport header is too small,
 857 *	%-EIO if a permanent problem occurred while marshaling.
 858 */
 859int
 860rpcrdma_marshal_req(struct rpcrdma_xprt *r_xprt, struct rpc_rqst *rqst)
 861{
 862	struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
 863	struct xdr_stream *xdr = &req->rl_stream;
 864	enum rpcrdma_chunktype rtype, wtype;
 865	struct xdr_buf *buf = &rqst->rq_snd_buf;
 866	bool ddp_allowed;
 867	__be32 *p;
 868	int ret;
 869
 870	if (unlikely(rqst->rq_rcv_buf.flags & XDRBUF_SPARSE_PAGES)) {
 871		ret = rpcrdma_alloc_sparse_pages(&rqst->rq_rcv_buf);
 872		if (ret)
 873			return ret;
 874	}
 875
 876	rpcrdma_set_xdrlen(&req->rl_hdrbuf, 0);
 877	xdr_init_encode(xdr, &req->rl_hdrbuf, rdmab_data(req->rl_rdmabuf),
 878			rqst);
 879
 880	/* Fixed header fields */
 881	ret = -EMSGSIZE;
 882	p = xdr_reserve_space(xdr, 4 * sizeof(*p));
 883	if (!p)
 884		goto out_err;
 885	*p++ = rqst->rq_xid;
 886	*p++ = rpcrdma_version;
 887	*p++ = r_xprt->rx_buf.rb_max_requests;
 888
 889	/* When the ULP employs a GSS flavor that guarantees integrity
 890	 * or privacy, direct data placement of individual data items
 891	 * is not allowed.
 892	 */
 893	ddp_allowed = !test_bit(RPCAUTH_AUTH_DATATOUCH,
 894				&rqst->rq_cred->cr_auth->au_flags);
 895
 896	/*
 897	 * Chunks needed for results?
 898	 *
 899	 * o If the expected result is under the inline threshold, all ops
 900	 *   return as inline.
 901	 * o Large read ops return data as write chunk(s), header as
 902	 *   inline.
 903	 * o Large non-read ops return as a single reply chunk.
 904	 */
 905	if (rpcrdma_results_inline(r_xprt, rqst))
 906		wtype = rpcrdma_noch;
 907	else if ((ddp_allowed && rqst->rq_rcv_buf.flags & XDRBUF_READ) &&
 908		 rpcrdma_nonpayload_inline(r_xprt, rqst))
 909		wtype = rpcrdma_writech;
 910	else
 911		wtype = rpcrdma_replych;
 912
 913	/*
 914	 * Chunks needed for arguments?
 915	 *
 916	 * o If the total request is under the inline threshold, all ops
 917	 *   are sent as inline.
 918	 * o Large write ops transmit data as read chunk(s), header as
 919	 *   inline.
 920	 * o Large non-write ops are sent with the entire message as a
 921	 *   single read chunk (protocol 0-position special case).
 922	 *
 923	 * This assumes that the upper layer does not present a request
 924	 * that both has a data payload, and whose non-data arguments
 925	 * by themselves are larger than the inline threshold.
 926	 */
 927	if (rpcrdma_args_inline(r_xprt, rqst)) {
 928		*p++ = rdma_msg;
 929		rtype = buf->len < rdmab_length(req->rl_sendbuf) ?
 930			rpcrdma_noch_pullup : rpcrdma_noch_mapped;
 931	} else if (ddp_allowed && buf->flags & XDRBUF_WRITE) {
 932		*p++ = rdma_msg;
 933		rtype = rpcrdma_readch;
 934	} else {
 935		r_xprt->rx_stats.nomsg_call_count++;
 936		*p++ = rdma_nomsg;
 937		rtype = rpcrdma_areadch;
 938	}
 939
 940	/* This implementation supports the following combinations
 941	 * of chunk lists in one RPC-over-RDMA Call message:
 942	 *
 943	 *   - Read list
 944	 *   - Write list
 945	 *   - Reply chunk
 946	 *   - Read list + Reply chunk
 947	 *
 948	 * It might not yet support the following combinations:
 949	 *
 950	 *   - Read list + Write list
 951	 *
 952	 * It does not support the following combinations:
 953	 *
 954	 *   - Write list + Reply chunk
 955	 *   - Read list + Write list + Reply chunk
 956	 *
 957	 * This implementation supports only a single chunk in each
 958	 * Read or Write list. Thus for example the client cannot
 959	 * send a Call message with a Position Zero Read chunk and a
 960	 * regular Read chunk at the same time.
 961	 */
 962	ret = rpcrdma_encode_read_list(r_xprt, req, rqst, rtype);
 963	if (ret)
 964		goto out_err;
 965	ret = rpcrdma_encode_write_list(r_xprt, req, rqst, wtype);
 966	if (ret)
 967		goto out_err;
 968	ret = rpcrdma_encode_reply_chunk(r_xprt, req, rqst, wtype);
 969	if (ret)
 970		goto out_err;
 971
 972	ret = rpcrdma_prepare_send_sges(r_xprt, req, req->rl_hdrbuf.len,
 973					buf, rtype);
 974	if (ret)
 975		goto out_err;
 976
 977	trace_xprtrdma_marshal(req, rtype, wtype);
 978	return 0;
 979
 980out_err:
 981	trace_xprtrdma_marshal_failed(rqst, ret);
 982	r_xprt->rx_stats.failed_marshal_count++;
 983	frwr_reset(req);
 984	return ret;
 985}
 986
 987static void __rpcrdma_update_cwnd_locked(struct rpc_xprt *xprt,
 988					 struct rpcrdma_buffer *buf,
 989					 u32 grant)
 990{
 991	buf->rb_credits = grant;
 992	xprt->cwnd = grant << RPC_CWNDSHIFT;
 993}
 994
 995static void rpcrdma_update_cwnd(struct rpcrdma_xprt *r_xprt, u32 grant)
 996{
 997	struct rpc_xprt *xprt = &r_xprt->rx_xprt;
 998
 999	spin_lock(&xprt->transport_lock);
1000	__rpcrdma_update_cwnd_locked(xprt, &r_xprt->rx_buf, grant);
1001	spin_unlock(&xprt->transport_lock);
1002}
1003
1004/**
1005 * rpcrdma_reset_cwnd - Reset the xprt's congestion window
1006 * @r_xprt: controlling transport instance
1007 *
1008 * Prepare @r_xprt for the next connection by reinitializing
1009 * its credit grant to one (see RFC 8166, Section 3.3.3).
1010 */
1011void rpcrdma_reset_cwnd(struct rpcrdma_xprt *r_xprt)
1012{
1013	struct rpc_xprt *xprt = &r_xprt->rx_xprt;
1014
1015	spin_lock(&xprt->transport_lock);
1016	xprt->cong = 0;
1017	__rpcrdma_update_cwnd_locked(xprt, &r_xprt->rx_buf, 1);
1018	spin_unlock(&xprt->transport_lock);
1019}
1020
1021/**
1022 * rpcrdma_inline_fixup - Scatter inline received data into rqst's iovecs
1023 * @rqst: controlling RPC request
1024 * @srcp: points to RPC message payload in receive buffer
1025 * @copy_len: remaining length of receive buffer content
1026 * @pad: Write chunk pad bytes needed (zero for pure inline)
1027 *
1028 * The upper layer has set the maximum number of bytes it can
1029 * receive in each component of rq_rcv_buf. These values are set in
1030 * the head.iov_len, page_len, tail.iov_len, and buflen fields.
1031 *
1032 * Unlike the TCP equivalent (xdr_partial_copy_from_skb), in
1033 * many cases this function simply updates iov_base pointers in
1034 * rq_rcv_buf to point directly to the received reply data, to
1035 * avoid copying reply data.
1036 *
1037 * Returns the count of bytes which had to be memcopied.
1038 */
1039static unsigned long
1040rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len, int pad)
1041{
1042	unsigned long fixup_copy_count;
1043	int i, npages, curlen;
1044	char *destp;
1045	struct page **ppages;
1046	int page_base;
1047
1048	/* The head iovec is redirected to the RPC reply message
1049	 * in the receive buffer, to avoid a memcopy.
1050	 */
1051	rqst->rq_rcv_buf.head[0].iov_base = srcp;
1052	rqst->rq_private_buf.head[0].iov_base = srcp;
1053
1054	/* The contents of the receive buffer that follow
1055	 * head.iov_len bytes are copied into the page list.
1056	 */
1057	curlen = rqst->rq_rcv_buf.head[0].iov_len;
1058	if (curlen > copy_len)
1059		curlen = copy_len;
1060	srcp += curlen;
1061	copy_len -= curlen;
1062
1063	ppages = rqst->rq_rcv_buf.pages +
1064		(rqst->rq_rcv_buf.page_base >> PAGE_SHIFT);
1065	page_base = offset_in_page(rqst->rq_rcv_buf.page_base);
1066	fixup_copy_count = 0;
1067	if (copy_len && rqst->rq_rcv_buf.page_len) {
1068		int pagelist_len;
1069
1070		pagelist_len = rqst->rq_rcv_buf.page_len;
1071		if (pagelist_len > copy_len)
1072			pagelist_len = copy_len;
1073		npages = PAGE_ALIGN(page_base + pagelist_len) >> PAGE_SHIFT;
1074		for (i = 0; i < npages; i++) {
1075			curlen = PAGE_SIZE - page_base;
1076			if (curlen > pagelist_len)
1077				curlen = pagelist_len;
1078
1079			destp = kmap_atomic(ppages[i]);
1080			memcpy(destp + page_base, srcp, curlen);
1081			flush_dcache_page(ppages[i]);
1082			kunmap_atomic(destp);
1083			srcp += curlen;
1084			copy_len -= curlen;
1085			fixup_copy_count += curlen;
1086			pagelist_len -= curlen;
1087			if (!pagelist_len)
1088				break;
1089			page_base = 0;
1090		}
1091
1092		/* Implicit padding for the last segment in a Write
1093		 * chunk is inserted inline at the front of the tail
1094		 * iovec. The upper layer ignores the content of
1095		 * the pad. Simply ensure inline content in the tail
1096		 * that follows the Write chunk is properly aligned.
1097		 */
1098		if (pad)
1099			srcp -= pad;
1100	}
1101
1102	/* The tail iovec is redirected to the remaining data
1103	 * in the receive buffer, to avoid a memcopy.
1104	 */
1105	if (copy_len || pad) {
1106		rqst->rq_rcv_buf.tail[0].iov_base = srcp;
1107		rqst->rq_private_buf.tail[0].iov_base = srcp;
1108	}
1109
1110	if (fixup_copy_count)
1111		trace_xprtrdma_fixup(rqst, fixup_copy_count);
1112	return fixup_copy_count;
1113}
1114
1115/* By convention, backchannel calls arrive via rdma_msg type
1116 * messages, and never populate the chunk lists. This makes
1117 * the RPC/RDMA header small and fixed in size, so it is
1118 * straightforward to check the RPC header's direction field.
1119 */
1120static bool
1121rpcrdma_is_bcall(struct rpcrdma_xprt *r_xprt, struct rpcrdma_rep *rep)
1122#if defined(CONFIG_SUNRPC_BACKCHANNEL)
1123{
1124	struct rpc_xprt *xprt = &r_xprt->rx_xprt;
1125	struct xdr_stream *xdr = &rep->rr_stream;
1126	__be32 *p;
1127
1128	if (rep->rr_proc != rdma_msg)
1129		return false;
1130
1131	/* Peek at stream contents without advancing. */
1132	p = xdr_inline_decode(xdr, 0);
1133
1134	/* Chunk lists */
1135	if (xdr_item_is_present(p++))
1136		return false;
1137	if (xdr_item_is_present(p++))
1138		return false;
1139	if (xdr_item_is_present(p++))
1140		return false;
1141
1142	/* RPC header */
1143	if (*p++ != rep->rr_xid)
1144		return false;
1145	if (*p != cpu_to_be32(RPC_CALL))
1146		return false;
1147
1148	/* No bc service. */
1149	if (xprt->bc_serv == NULL)
1150		return false;
1151
1152	/* Now that we are sure this is a backchannel call,
1153	 * advance to the RPC header.
1154	 */
1155	p = xdr_inline_decode(xdr, 3 * sizeof(*p));
1156	if (unlikely(!p))
1157		return true;
1158
1159	rpcrdma_bc_receive_call(r_xprt, rep);
1160	return true;
1161}
1162#else	/* CONFIG_SUNRPC_BACKCHANNEL */
1163{
1164	return false;
1165}
1166#endif	/* CONFIG_SUNRPC_BACKCHANNEL */
1167
1168static int decode_rdma_segment(struct xdr_stream *xdr, u32 *length)
1169{
1170	u32 handle;
1171	u64 offset;
1172	__be32 *p;
1173
1174	p = xdr_inline_decode(xdr, 4 * sizeof(*p));
1175	if (unlikely(!p))
1176		return -EIO;
1177
1178	xdr_decode_rdma_segment(p, &handle, length, &offset);
1179	trace_xprtrdma_decode_seg(handle, *length, offset);
1180	return 0;
1181}
1182
1183static int decode_write_chunk(struct xdr_stream *xdr, u32 *length)
1184{
1185	u32 segcount, seglength;
1186	__be32 *p;
1187
1188	p = xdr_inline_decode(xdr, sizeof(*p));
1189	if (unlikely(!p))
1190		return -EIO;
1191
1192	*length = 0;
1193	segcount = be32_to_cpup(p);
1194	while (segcount--) {
1195		if (decode_rdma_segment(xdr, &seglength))
1196			return -EIO;
1197		*length += seglength;
1198	}
1199
1200	return 0;
1201}
1202
1203/* In RPC-over-RDMA Version One replies, a Read list is never
1204 * expected. This decoder is a stub that returns an error if
1205 * a Read list is present.
1206 */
1207static int decode_read_list(struct xdr_stream *xdr)
1208{
1209	__be32 *p;
1210
1211	p = xdr_inline_decode(xdr, sizeof(*p));
1212	if (unlikely(!p))
1213		return -EIO;
1214	if (unlikely(xdr_item_is_present(p)))
1215		return -EIO;
1216	return 0;
1217}
1218
1219/* Supports only one Write chunk in the Write list
1220 */
1221static int decode_write_list(struct xdr_stream *xdr, u32 *length)
1222{
1223	u32 chunklen;
1224	bool first;
1225	__be32 *p;
1226
1227	*length = 0;
1228	first = true;
1229	do {
1230		p = xdr_inline_decode(xdr, sizeof(*p));
1231		if (unlikely(!p))
1232			return -EIO;
1233		if (xdr_item_is_absent(p))
1234			break;
1235		if (!first)
1236			return -EIO;
1237
1238		if (decode_write_chunk(xdr, &chunklen))
1239			return -EIO;
1240		*length += chunklen;
1241		first = false;
1242	} while (true);
1243	return 0;
1244}
1245
1246static int decode_reply_chunk(struct xdr_stream *xdr, u32 *length)
1247{
1248	__be32 *p;
1249
1250	p = xdr_inline_decode(xdr, sizeof(*p));
1251	if (unlikely(!p))
1252		return -EIO;
1253
1254	*length = 0;
1255	if (xdr_item_is_present(p))
1256		if (decode_write_chunk(xdr, length))
1257			return -EIO;
1258	return 0;
1259}
1260
1261static int
1262rpcrdma_decode_msg(struct rpcrdma_xprt *r_xprt, struct rpcrdma_rep *rep,
1263		   struct rpc_rqst *rqst)
1264{
1265	struct xdr_stream *xdr = &rep->rr_stream;
1266	u32 writelist, replychunk, rpclen;
1267	char *base;
1268
1269	/* Decode the chunk lists */
1270	if (decode_read_list(xdr))
1271		return -EIO;
1272	if (decode_write_list(xdr, &writelist))
1273		return -EIO;
1274	if (decode_reply_chunk(xdr, &replychunk))
1275		return -EIO;
1276
1277	/* RDMA_MSG sanity checks */
1278	if (unlikely(replychunk))
1279		return -EIO;
1280
1281	/* Build the RPC reply's Payload stream in rqst->rq_rcv_buf */
1282	base = (char *)xdr_inline_decode(xdr, 0);
1283	rpclen = xdr_stream_remaining(xdr);
1284	r_xprt->rx_stats.fixup_copy_count +=
1285		rpcrdma_inline_fixup(rqst, base, rpclen, writelist & 3);
1286
1287	r_xprt->rx_stats.total_rdma_reply += writelist;
1288	return rpclen + xdr_align_size(writelist);
1289}
1290
1291static noinline int
1292rpcrdma_decode_nomsg(struct rpcrdma_xprt *r_xprt, struct rpcrdma_rep *rep)
1293{
1294	struct xdr_stream *xdr = &rep->rr_stream;
1295	u32 writelist, replychunk;
1296
1297	/* Decode the chunk lists */
1298	if (decode_read_list(xdr))
1299		return -EIO;
1300	if (decode_write_list(xdr, &writelist))
1301		return -EIO;
1302	if (decode_reply_chunk(xdr, &replychunk))
1303		return -EIO;
1304
1305	/* RDMA_NOMSG sanity checks */
1306	if (unlikely(writelist))
1307		return -EIO;
1308	if (unlikely(!replychunk))
1309		return -EIO;
1310
1311	/* Reply chunk buffer already is the reply vector */
1312	r_xprt->rx_stats.total_rdma_reply += replychunk;
1313	return replychunk;
1314}
1315
1316static noinline int
1317rpcrdma_decode_error(struct rpcrdma_xprt *r_xprt, struct rpcrdma_rep *rep,
1318		     struct rpc_rqst *rqst)
1319{
1320	struct xdr_stream *xdr = &rep->rr_stream;
1321	__be32 *p;
1322
1323	p = xdr_inline_decode(xdr, sizeof(*p));
1324	if (unlikely(!p))
1325		return -EIO;
1326
1327	switch (*p) {
1328	case err_vers:
1329		p = xdr_inline_decode(xdr, 2 * sizeof(*p));
1330		if (!p)
1331			break;
1332		trace_xprtrdma_err_vers(rqst, p, p + 1);
1333		break;
1334	case err_chunk:
1335		trace_xprtrdma_err_chunk(rqst);
1336		break;
1337	default:
1338		trace_xprtrdma_err_unrecognized(rqst, p);
1339	}
1340
1341	return -EIO;
1342}
1343
1344/**
1345 * rpcrdma_unpin_rqst - Release rqst without completing it
1346 * @rep: RPC/RDMA Receive context
1347 *
1348 * This is done when a connection is lost so that a Reply
1349 * can be dropped and its matching Call can be subsequently
1350 * retransmitted on a new connection.
1351 */
1352void rpcrdma_unpin_rqst(struct rpcrdma_rep *rep)
1353{
1354	struct rpc_xprt *xprt = &rep->rr_rxprt->rx_xprt;
1355	struct rpc_rqst *rqst = rep->rr_rqst;
1356	struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
1357
1358	req->rl_reply = NULL;
1359	rep->rr_rqst = NULL;
1360
1361	spin_lock(&xprt->queue_lock);
1362	xprt_unpin_rqst(rqst);
1363	spin_unlock(&xprt->queue_lock);
1364}
1365
1366/**
1367 * rpcrdma_complete_rqst - Pass completed rqst back to RPC
1368 * @rep: RPC/RDMA Receive context
1369 *
1370 * Reconstruct the RPC reply and complete the transaction
1371 * while @rqst is still pinned to ensure the rep, rqst, and
1372 * rq_task pointers remain stable.
1373 */
1374void rpcrdma_complete_rqst(struct rpcrdma_rep *rep)
1375{
1376	struct rpcrdma_xprt *r_xprt = rep->rr_rxprt;
1377	struct rpc_xprt *xprt = &r_xprt->rx_xprt;
1378	struct rpc_rqst *rqst = rep->rr_rqst;
1379	int status;
1380
1381	switch (rep->rr_proc) {
1382	case rdma_msg:
1383		status = rpcrdma_decode_msg(r_xprt, rep, rqst);
1384		break;
1385	case rdma_nomsg:
1386		status = rpcrdma_decode_nomsg(r_xprt, rep);
1387		break;
1388	case rdma_error:
1389		status = rpcrdma_decode_error(r_xprt, rep, rqst);
1390		break;
1391	default:
1392		status = -EIO;
1393	}
1394	if (status < 0)
1395		goto out_badheader;
1396
1397out:
1398	spin_lock(&xprt->queue_lock);
1399	xprt_complete_rqst(rqst->rq_task, status);
1400	xprt_unpin_rqst(rqst);
1401	spin_unlock(&xprt->queue_lock);
1402	return;
1403
1404out_badheader:
1405	trace_xprtrdma_reply_hdr_err(rep);
1406	r_xprt->rx_stats.bad_reply_count++;
1407	rqst->rq_task->tk_status = status;
1408	status = 0;
1409	goto out;
1410}
1411
1412static void rpcrdma_reply_done(struct kref *kref)
1413{
1414	struct rpcrdma_req *req =
1415		container_of(kref, struct rpcrdma_req, rl_kref);
1416
1417	rpcrdma_complete_rqst(req->rl_reply);
1418}
1419
1420/**
1421 * rpcrdma_reply_handler - Process received RPC/RDMA messages
1422 * @rep: Incoming rpcrdma_rep object to process
1423 *
1424 * Errors must result in the RPC task either being awakened, or
1425 * allowed to timeout, to discover the errors at that time.
1426 */
1427void rpcrdma_reply_handler(struct rpcrdma_rep *rep)
1428{
1429	struct rpcrdma_xprt *r_xprt = rep->rr_rxprt;
1430	struct rpc_xprt *xprt = &r_xprt->rx_xprt;
1431	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
1432	struct rpcrdma_req *req;
1433	struct rpc_rqst *rqst;
1434	u32 credits;
1435	__be32 *p;
1436
1437	/* Any data means we had a useful conversation, so
1438	 * then we don't need to delay the next reconnect.
1439	 */
1440	if (xprt->reestablish_timeout)
1441		xprt->reestablish_timeout = 0;
1442
1443	/* Fixed transport header fields */
1444	xdr_init_decode(&rep->rr_stream, &rep->rr_hdrbuf,
1445			rep->rr_hdrbuf.head[0].iov_base, NULL);
1446	p = xdr_inline_decode(&rep->rr_stream, 4 * sizeof(*p));
1447	if (unlikely(!p))
1448		goto out_shortreply;
1449	rep->rr_xid = *p++;
1450	rep->rr_vers = *p++;
1451	credits = be32_to_cpu(*p++);
1452	rep->rr_proc = *p++;
1453
1454	if (rep->rr_vers != rpcrdma_version)
1455		goto out_badversion;
1456
1457	if (rpcrdma_is_bcall(r_xprt, rep))
1458		return;
1459
1460	/* Match incoming rpcrdma_rep to an rpcrdma_req to
1461	 * get context for handling any incoming chunks.
1462	 */
1463	spin_lock(&xprt->queue_lock);
1464	rqst = xprt_lookup_rqst(xprt, rep->rr_xid);
1465	if (!rqst)
1466		goto out_norqst;
1467	xprt_pin_rqst(rqst);
1468	spin_unlock(&xprt->queue_lock);
1469
1470	if (credits == 0)
1471		credits = 1;	/* don't deadlock */
1472	else if (credits > r_xprt->rx_ep->re_max_requests)
1473		credits = r_xprt->rx_ep->re_max_requests;
1474	rpcrdma_post_recvs(r_xprt, credits + (buf->rb_bc_srv_max_requests << 1));
1475	if (buf->rb_credits != credits)
1476		rpcrdma_update_cwnd(r_xprt, credits);
1477
1478	req = rpcr_to_rdmar(rqst);
1479	if (unlikely(req->rl_reply))
1480		rpcrdma_rep_put(buf, req->rl_reply);
1481	req->rl_reply = rep;
1482	rep->rr_rqst = rqst;
1483
1484	trace_xprtrdma_reply(rqst->rq_task, rep, credits);
1485
1486	if (rep->rr_wc_flags & IB_WC_WITH_INVALIDATE)
1487		frwr_reminv(rep, &req->rl_registered);
1488	if (!list_empty(&req->rl_registered))
1489		frwr_unmap_async(r_xprt, req);
1490		/* LocalInv completion will complete the RPC */
1491	else
1492		kref_put(&req->rl_kref, rpcrdma_reply_done);
1493	return;
1494
1495out_badversion:
1496	trace_xprtrdma_reply_vers_err(rep);
1497	goto out;
1498
1499out_norqst:
1500	spin_unlock(&xprt->queue_lock);
1501	trace_xprtrdma_reply_rqst_err(rep);
1502	goto out;
1503
1504out_shortreply:
1505	trace_xprtrdma_reply_short_err(rep);
1506
1507out:
1508	rpcrdma_rep_put(buf, rep);
1509}