v4.19.13 snapshot.
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
new file mode 100644
index 0000000..c8ae983
--- /dev/null
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -0,0 +1,1395 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * Copyright (c) 2014-2017 Oracle. All rights reserved.
+ * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses. You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the BSD-type
+ * license below:
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimer in the documentation and/or other materials provided
+ * with the distribution.
+ *
+ * Neither the name of the Network Appliance, Inc. nor the names of
+ * its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written
+ * permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * rpc_rdma.c
+ *
+ * This file contains the guts of the RPC RDMA protocol, and
+ * does marshaling/unmarshaling, etc. It is also where interfacing
+ * to the Linux RPC framework lives.
+ */
+
+#include <linux/highmem.h>
+
+#include <linux/sunrpc/svc_rdma.h>
+
+#include "xprt_rdma.h"
+#include <trace/events/rpcrdma.h>
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+# define RPCDBG_FACILITY RPCDBG_TRANS
+#endif
+
+/* Returns size of largest RPC-over-RDMA header in a Call message
+ *
+ * The largest Call header contains a full-size Read list and a
+ * minimal Reply chunk.
+ */
+static unsigned int rpcrdma_max_call_header_size(unsigned int maxsegs)
+{
+ unsigned int size;
+
+ /* Fixed header fields and list discriminators */
+ size = RPCRDMA_HDRLEN_MIN;
+
+ /* Maximum Read list size */
+ maxsegs += 2; /* segment for head and tail buffers */
+ size = maxsegs * rpcrdma_readchunk_maxsz * sizeof(__be32);
+
+ /* Minimal Read chunk size */
+ size += sizeof(__be32); /* segment count */
+ size += rpcrdma_segment_maxsz * sizeof(__be32);
+ size += sizeof(__be32); /* list discriminator */
+
+ dprintk("RPC: %s: max call header size = %u\n",
+ __func__, size);
+ return size;
+}
+
+/* Returns size of largest RPC-over-RDMA header in a Reply message
+ *
+ * There is only one Write list or one Reply chunk per Reply
+ * message. The larger list is the Write list.
+ */
+static unsigned int rpcrdma_max_reply_header_size(unsigned int maxsegs)
+{
+ unsigned int size;
+
+ /* Fixed header fields and list discriminators */
+ size = RPCRDMA_HDRLEN_MIN;
+
+ /* Maximum Write list size */
+ maxsegs += 2; /* segment for head and tail buffers */
+ size = sizeof(__be32); /* segment count */
+ size += maxsegs * rpcrdma_segment_maxsz * sizeof(__be32);
+ size += sizeof(__be32); /* list discriminator */
+
+ dprintk("RPC: %s: max reply header size = %u\n",
+ __func__, size);
+ return size;
+}
+
+void rpcrdma_set_max_header_sizes(struct rpcrdma_xprt *r_xprt)
+{
+ struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
+ struct rpcrdma_ia *ia = &r_xprt->rx_ia;
+ unsigned int maxsegs = ia->ri_max_segs;
+
+ ia->ri_max_inline_write = cdata->inline_wsize -
+ rpcrdma_max_call_header_size(maxsegs);
+ ia->ri_max_inline_read = cdata->inline_rsize -
+ rpcrdma_max_reply_header_size(maxsegs);
+}
+
+/* The client can send a request inline as long as the RPCRDMA header
+ * plus the RPC call fit under the transport's inline limit. If the
+ * combined call message size exceeds that limit, the client must use
+ * a Read chunk for this operation.
+ *
+ * A Read chunk is also required if sending the RPC call inline would
+ * exceed this device's max_sge limit.
+ */
+static bool rpcrdma_args_inline(struct rpcrdma_xprt *r_xprt,
+ struct rpc_rqst *rqst)
+{
+ struct xdr_buf *xdr = &rqst->rq_snd_buf;
+ unsigned int count, remaining, offset;
+
+ if (xdr->len > r_xprt->rx_ia.ri_max_inline_write)
+ return false;
+
+ if (xdr->page_len) {
+ remaining = xdr->page_len;
+ offset = offset_in_page(xdr->page_base);
+ count = RPCRDMA_MIN_SEND_SGES;
+ while (remaining) {
+ remaining -= min_t(unsigned int,
+ PAGE_SIZE - offset, remaining);
+ offset = 0;
+ if (++count > r_xprt->rx_ia.ri_max_send_sges)
+ return false;
+ }
+ }
+
+ return true;
+}
+
+/* The client can't know how large the actual reply will be. Thus it
+ * plans for the largest possible reply for that particular ULP
+ * operation. If the maximum combined reply message size exceeds that
+ * limit, the client must provide a write list or a reply chunk for
+ * this request.
+ */
+static bool rpcrdma_results_inline(struct rpcrdma_xprt *r_xprt,
+ struct rpc_rqst *rqst)
+{
+ struct rpcrdma_ia *ia = &r_xprt->rx_ia;
+
+ return rqst->rq_rcv_buf.buflen <= ia->ri_max_inline_read;
+}
+
+/* Split @vec on page boundaries into SGEs. FMR registers pages, not
+ * a byte range. Other modes coalesce these SGEs into a single MR
+ * when they can.
+ *
+ * Returns pointer to next available SGE, and bumps the total number
+ * of SGEs consumed.
+ */
+static struct rpcrdma_mr_seg *
+rpcrdma_convert_kvec(struct kvec *vec, struct rpcrdma_mr_seg *seg,
+ unsigned int *n)
+{
+ u32 remaining, page_offset;
+ char *base;
+
+ base = vec->iov_base;
+ page_offset = offset_in_page(base);
+ remaining = vec->iov_len;
+ while (remaining) {
+ seg->mr_page = NULL;
+ seg->mr_offset = base;
+ seg->mr_len = min_t(u32, PAGE_SIZE - page_offset, remaining);
+ remaining -= seg->mr_len;
+ base += seg->mr_len;
+ ++seg;
+ ++(*n);
+ page_offset = 0;
+ }
+ return seg;
+}
+
+/* Convert @xdrbuf into SGEs no larger than a page each. As they
+ * are registered, these SGEs are then coalesced into RDMA segments
+ * when the selected memreg mode supports it.
+ *
+ * Returns positive number of SGEs consumed, or a negative errno.
+ */
+
+static int
+rpcrdma_convert_iovs(struct rpcrdma_xprt *r_xprt, struct xdr_buf *xdrbuf,
+ unsigned int pos, enum rpcrdma_chunktype type,
+ struct rpcrdma_mr_seg *seg)
+{
+ unsigned long page_base;
+ unsigned int len, n;
+ struct page **ppages;
+
+ n = 0;
+ if (pos == 0)
+ seg = rpcrdma_convert_kvec(&xdrbuf->head[0], seg, &n);
+
+ len = xdrbuf->page_len;
+ ppages = xdrbuf->pages + (xdrbuf->page_base >> PAGE_SHIFT);
+ page_base = offset_in_page(xdrbuf->page_base);
+ while (len) {
+ if (unlikely(!*ppages)) {
+ /* XXX: Certain upper layer operations do
+ * not provide receive buffer pages.
+ */
+ *ppages = alloc_page(GFP_ATOMIC);
+ if (!*ppages)
+ return -ENOBUFS;
+ }
+ seg->mr_page = *ppages;
+ seg->mr_offset = (char *)page_base;
+ seg->mr_len = min_t(u32, PAGE_SIZE - page_base, len);
+ len -= seg->mr_len;
+ ++ppages;
+ ++seg;
+ ++n;
+ page_base = 0;
+ }
+
+ /* When encoding a Read chunk, the tail iovec contains an
+ * XDR pad and may be omitted.
+ */
+ if (type == rpcrdma_readch && r_xprt->rx_ia.ri_implicit_roundup)
+ goto out;
+
+ /* When encoding a Write chunk, some servers need to see an
+ * extra segment for non-XDR-aligned Write chunks. The upper
+ * layer provides space in the tail iovec that may be used
+ * for this purpose.
+ */
+ if (type == rpcrdma_writech && r_xprt->rx_ia.ri_implicit_roundup)
+ goto out;
+
+ if (xdrbuf->tail[0].iov_len)
+ seg = rpcrdma_convert_kvec(&xdrbuf->tail[0], seg, &n);
+
+out:
+ if (unlikely(n > RPCRDMA_MAX_SEGS))
+ return -EIO;
+ return n;
+}
+
+static inline int
+encode_item_present(struct xdr_stream *xdr)
+{
+ __be32 *p;
+
+ p = xdr_reserve_space(xdr, sizeof(*p));
+ if (unlikely(!p))
+ return -EMSGSIZE;
+
+ *p = xdr_one;
+ return 0;
+}
+
+static inline int
+encode_item_not_present(struct xdr_stream *xdr)
+{
+ __be32 *p;
+
+ p = xdr_reserve_space(xdr, sizeof(*p));
+ if (unlikely(!p))
+ return -EMSGSIZE;
+
+ *p = xdr_zero;
+ return 0;
+}
+
+static void
+xdr_encode_rdma_segment(__be32 *iptr, struct rpcrdma_mr *mr)
+{
+ *iptr++ = cpu_to_be32(mr->mr_handle);
+ *iptr++ = cpu_to_be32(mr->mr_length);
+ xdr_encode_hyper(iptr, mr->mr_offset);
+}
+
+static int
+encode_rdma_segment(struct xdr_stream *xdr, struct rpcrdma_mr *mr)
+{
+ __be32 *p;
+
+ p = xdr_reserve_space(xdr, 4 * sizeof(*p));
+ if (unlikely(!p))
+ return -EMSGSIZE;
+
+ xdr_encode_rdma_segment(p, mr);
+ return 0;
+}
+
+static int
+encode_read_segment(struct xdr_stream *xdr, struct rpcrdma_mr *mr,
+ u32 position)
+{
+ __be32 *p;
+
+ p = xdr_reserve_space(xdr, 6 * sizeof(*p));
+ if (unlikely(!p))
+ return -EMSGSIZE;
+
+ *p++ = xdr_one; /* Item present */
+ *p++ = cpu_to_be32(position);
+ xdr_encode_rdma_segment(p, mr);
+ return 0;
+}
+
+/* Register and XDR encode the Read list. Supports encoding a list of read
+ * segments that belong to a single read chunk.
+ *
+ * Encoding key for single-list chunks (HLOO = Handle32 Length32 Offset64):
+ *
+ * Read chunklist (a linked list):
+ * N elements, position P (same P for all chunks of same arg!):
+ * 1 - PHLOO - 1 - PHLOO - ... - 1 - PHLOO - 0
+ *
+ * Returns zero on success, or a negative errno if a failure occurred.
+ * @xdr is advanced to the next position in the stream.
+ *
+ * Only a single @pos value is currently supported.
+ */
+static noinline int
+rpcrdma_encode_read_list(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req,
+ struct rpc_rqst *rqst, enum rpcrdma_chunktype rtype)
+{
+ struct xdr_stream *xdr = &req->rl_stream;
+ struct rpcrdma_mr_seg *seg;
+ struct rpcrdma_mr *mr;
+ unsigned int pos;
+ int nsegs;
+
+ pos = rqst->rq_snd_buf.head[0].iov_len;
+ if (rtype == rpcrdma_areadch)
+ pos = 0;
+ seg = req->rl_segments;
+ nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_snd_buf, pos,
+ rtype, seg);
+ if (nsegs < 0)
+ return nsegs;
+
+ do {
+ seg = r_xprt->rx_ia.ri_ops->ro_map(r_xprt, seg, nsegs,
+ false, &mr);
+ if (IS_ERR(seg))
+ return PTR_ERR(seg);
+ rpcrdma_mr_push(mr, &req->rl_registered);
+
+ if (encode_read_segment(xdr, mr, pos) < 0)
+ return -EMSGSIZE;
+
+ trace_xprtrdma_read_chunk(rqst->rq_task, pos, mr, nsegs);
+ r_xprt->rx_stats.read_chunk_count++;
+ nsegs -= mr->mr_nents;
+ } while (nsegs);
+
+ return 0;
+}
+
+/* Register and XDR encode the Write list. Supports encoding a list
+ * containing one array of plain segments that belong to a single
+ * write chunk.
+ *
+ * Encoding key for single-list chunks (HLOO = Handle32 Length32 Offset64):
+ *
+ * Write chunklist (a list of (one) counted array):
+ * N elements:
+ * 1 - N - HLOO - HLOO - ... - HLOO - 0
+ *
+ * Returns zero on success, or a negative errno if a failure occurred.
+ * @xdr is advanced to the next position in the stream.
+ *
+ * Only a single Write chunk is currently supported.
+ */
+static noinline int
+rpcrdma_encode_write_list(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req,
+ struct rpc_rqst *rqst, enum rpcrdma_chunktype wtype)
+{
+ struct xdr_stream *xdr = &req->rl_stream;
+ struct rpcrdma_mr_seg *seg;
+ struct rpcrdma_mr *mr;
+ int nsegs, nchunks;
+ __be32 *segcount;
+
+ seg = req->rl_segments;
+ nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_rcv_buf,
+ rqst->rq_rcv_buf.head[0].iov_len,
+ wtype, seg);
+ if (nsegs < 0)
+ return nsegs;
+
+ if (encode_item_present(xdr) < 0)
+ return -EMSGSIZE;
+ segcount = xdr_reserve_space(xdr, sizeof(*segcount));
+ if (unlikely(!segcount))
+ return -EMSGSIZE;
+ /* Actual value encoded below */
+
+ nchunks = 0;
+ do {
+ seg = r_xprt->rx_ia.ri_ops->ro_map(r_xprt, seg, nsegs,
+ true, &mr);
+ if (IS_ERR(seg))
+ return PTR_ERR(seg);
+ rpcrdma_mr_push(mr, &req->rl_registered);
+
+ if (encode_rdma_segment(xdr, mr) < 0)
+ return -EMSGSIZE;
+
+ trace_xprtrdma_write_chunk(rqst->rq_task, mr, nsegs);
+ r_xprt->rx_stats.write_chunk_count++;
+ r_xprt->rx_stats.total_rdma_request += mr->mr_length;
+ nchunks++;
+ nsegs -= mr->mr_nents;
+ } while (nsegs);
+
+ /* Update count of segments in this Write chunk */
+ *segcount = cpu_to_be32(nchunks);
+
+ return 0;
+}
+
+/* Register and XDR encode the Reply chunk. Supports encoding an array
+ * of plain segments that belong to a single write (reply) chunk.
+ *
+ * Encoding key for single-list chunks (HLOO = Handle32 Length32 Offset64):
+ *
+ * Reply chunk (a counted array):
+ * N elements:
+ * 1 - N - HLOO - HLOO - ... - HLOO
+ *
+ * Returns zero on success, or a negative errno if a failure occurred.
+ * @xdr is advanced to the next position in the stream.
+ */
+static noinline int
+rpcrdma_encode_reply_chunk(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req,
+ struct rpc_rqst *rqst, enum rpcrdma_chunktype wtype)
+{
+ struct xdr_stream *xdr = &req->rl_stream;
+ struct rpcrdma_mr_seg *seg;
+ struct rpcrdma_mr *mr;
+ int nsegs, nchunks;
+ __be32 *segcount;
+
+ seg = req->rl_segments;
+ nsegs = rpcrdma_convert_iovs(r_xprt, &rqst->rq_rcv_buf, 0, wtype, seg);
+ if (nsegs < 0)
+ return nsegs;
+
+ if (encode_item_present(xdr) < 0)
+ return -EMSGSIZE;
+ segcount = xdr_reserve_space(xdr, sizeof(*segcount));
+ if (unlikely(!segcount))
+ return -EMSGSIZE;
+ /* Actual value encoded below */
+
+ nchunks = 0;
+ do {
+ seg = r_xprt->rx_ia.ri_ops->ro_map(r_xprt, seg, nsegs,
+ true, &mr);
+ if (IS_ERR(seg))
+ return PTR_ERR(seg);
+ rpcrdma_mr_push(mr, &req->rl_registered);
+
+ if (encode_rdma_segment(xdr, mr) < 0)
+ return -EMSGSIZE;
+
+ trace_xprtrdma_reply_chunk(rqst->rq_task, mr, nsegs);
+ r_xprt->rx_stats.reply_chunk_count++;
+ r_xprt->rx_stats.total_rdma_request += mr->mr_length;
+ nchunks++;
+ nsegs -= mr->mr_nents;
+ } while (nsegs);
+
+ /* Update count of segments in the Reply chunk */
+ *segcount = cpu_to_be32(nchunks);
+
+ return 0;
+}
+
+/**
+ * rpcrdma_unmap_sendctx - DMA-unmap Send buffers
+ * @sc: sendctx containing SGEs to unmap
+ *
+ */
+void
+rpcrdma_unmap_sendctx(struct rpcrdma_sendctx *sc)
+{
+ struct rpcrdma_ia *ia = &sc->sc_xprt->rx_ia;
+ struct ib_sge *sge;
+ unsigned int count;
+
+ /* The first two SGEs contain the transport header and
+ * the inline buffer. These are always left mapped so
+ * they can be cheaply re-used.
+ */
+ sge = &sc->sc_sges[2];
+ for (count = sc->sc_unmap_count; count; ++sge, --count)
+ ib_dma_unmap_page(ia->ri_device,
+ sge->addr, sge->length, DMA_TO_DEVICE);
+
+ if (test_and_clear_bit(RPCRDMA_REQ_F_TX_RESOURCES, &sc->sc_req->rl_flags)) {
+ smp_mb__after_atomic();
+ wake_up_bit(&sc->sc_req->rl_flags, RPCRDMA_REQ_F_TX_RESOURCES);
+ }
+}
+
+/* Prepare an SGE for the RPC-over-RDMA transport header.
+ */
+static bool
+rpcrdma_prepare_hdr_sge(struct rpcrdma_ia *ia, struct rpcrdma_req *req,
+ u32 len)
+{
+ struct rpcrdma_sendctx *sc = req->rl_sendctx;
+ struct rpcrdma_regbuf *rb = req->rl_rdmabuf;
+ struct ib_sge *sge = sc->sc_sges;
+
+ if (!rpcrdma_dma_map_regbuf(ia, rb))
+ goto out_regbuf;
+ sge->addr = rdmab_addr(rb);
+ sge->length = len;
+ sge->lkey = rdmab_lkey(rb);
+
+ ib_dma_sync_single_for_device(rdmab_device(rb), sge->addr,
+ sge->length, DMA_TO_DEVICE);
+ sc->sc_wr.num_sge++;
+ return true;
+
+out_regbuf:
+ pr_err("rpcrdma: failed to DMA map a Send buffer\n");
+ return false;
+}
+
+/* Prepare the Send SGEs. The head and tail iovec, and each entry
+ * in the page list, gets its own SGE.
+ */
+static bool
+rpcrdma_prepare_msg_sges(struct rpcrdma_ia *ia, struct rpcrdma_req *req,
+ struct xdr_buf *xdr, enum rpcrdma_chunktype rtype)
+{
+ struct rpcrdma_sendctx *sc = req->rl_sendctx;
+ unsigned int sge_no, page_base, len, remaining;
+ struct rpcrdma_regbuf *rb = req->rl_sendbuf;
+ struct ib_device *device = ia->ri_device;
+ struct ib_sge *sge = sc->sc_sges;
+ u32 lkey = ia->ri_pd->local_dma_lkey;
+ struct page *page, **ppages;
+
+ /* The head iovec is straightforward, as it is already
+ * DMA-mapped. Sync the content that has changed.
+ */
+ if (!rpcrdma_dma_map_regbuf(ia, rb))
+ goto out_regbuf;
+ sge_no = 1;
+ sge[sge_no].addr = rdmab_addr(rb);
+ sge[sge_no].length = xdr->head[0].iov_len;
+ sge[sge_no].lkey = rdmab_lkey(rb);
+ ib_dma_sync_single_for_device(rdmab_device(rb), sge[sge_no].addr,
+ sge[sge_no].length, DMA_TO_DEVICE);
+
+ /* If there is a Read chunk, the page list is being handled
+ * via explicit RDMA, and thus is skipped here. However, the
+ * tail iovec may include an XDR pad for the page list, as
+ * well as additional content, and may not reside in the
+ * same page as the head iovec.
+ */
+ if (rtype == rpcrdma_readch) {
+ len = xdr->tail[0].iov_len;
+
+ /* Do not include the tail if it is only an XDR pad */
+ if (len < 4)
+ goto out;
+
+ page = virt_to_page(xdr->tail[0].iov_base);
+ page_base = offset_in_page(xdr->tail[0].iov_base);
+
+ /* If the content in the page list is an odd length,
+ * xdr_write_pages() has added a pad at the beginning
+ * of the tail iovec. Force the tail's non-pad content
+ * to land at the next XDR position in the Send message.
+ */
+ page_base += len & 3;
+ len -= len & 3;
+ goto map_tail;
+ }
+
+ /* If there is a page list present, temporarily DMA map
+ * and prepare an SGE for each page to be sent.
+ */
+ if (xdr->page_len) {
+ ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
+ page_base = offset_in_page(xdr->page_base);
+ remaining = xdr->page_len;
+ while (remaining) {
+ sge_no++;
+ if (sge_no > RPCRDMA_MAX_SEND_SGES - 2)
+ goto out_mapping_overflow;
+
+ len = min_t(u32, PAGE_SIZE - page_base, remaining);
+ sge[sge_no].addr = ib_dma_map_page(device, *ppages,
+ page_base, len,
+ DMA_TO_DEVICE);
+ if (ib_dma_mapping_error(device, sge[sge_no].addr))
+ goto out_mapping_err;
+ sge[sge_no].length = len;
+ sge[sge_no].lkey = lkey;
+
+ sc->sc_unmap_count++;
+ ppages++;
+ remaining -= len;
+ page_base = 0;
+ }
+ }
+
+ /* The tail iovec is not always constructed in the same
+ * page where the head iovec resides (see, for example,
+ * gss_wrap_req_priv). To neatly accommodate that case,
+ * DMA map it separately.
+ */
+ if (xdr->tail[0].iov_len) {
+ page = virt_to_page(xdr->tail[0].iov_base);
+ page_base = offset_in_page(xdr->tail[0].iov_base);
+ len = xdr->tail[0].iov_len;
+
+map_tail:
+ sge_no++;
+ sge[sge_no].addr = ib_dma_map_page(device, page,
+ page_base, len,
+ DMA_TO_DEVICE);
+ if (ib_dma_mapping_error(device, sge[sge_no].addr))
+ goto out_mapping_err;
+ sge[sge_no].length = len;
+ sge[sge_no].lkey = lkey;
+ sc->sc_unmap_count++;
+ }
+
+out:
+ sc->sc_wr.num_sge += sge_no;
+ if (sc->sc_unmap_count)
+ __set_bit(RPCRDMA_REQ_F_TX_RESOURCES, &req->rl_flags);
+ return true;
+
+out_regbuf:
+ pr_err("rpcrdma: failed to DMA map a Send buffer\n");
+ return false;
+
+out_mapping_overflow:
+ rpcrdma_unmap_sendctx(sc);
+ pr_err("rpcrdma: too many Send SGEs (%u)\n", sge_no);
+ return false;
+
+out_mapping_err:
+ rpcrdma_unmap_sendctx(sc);
+ pr_err("rpcrdma: Send mapping error\n");
+ return false;
+}
+
+/**
+ * rpcrdma_prepare_send_sges - Construct SGEs for a Send WR
+ * @r_xprt: controlling transport
+ * @req: context of RPC Call being marshalled
+ * @hdrlen: size of transport header, in bytes
+ * @xdr: xdr_buf containing RPC Call
+ * @rtype: chunk type being encoded
+ *
+ * Returns 0 on success; otherwise a negative errno is returned.
+ */
+int
+rpcrdma_prepare_send_sges(struct rpcrdma_xprt *r_xprt,
+ struct rpcrdma_req *req, u32 hdrlen,
+ struct xdr_buf *xdr, enum rpcrdma_chunktype rtype)
+{
+ req->rl_sendctx = rpcrdma_sendctx_get_locked(&r_xprt->rx_buf);
+ if (!req->rl_sendctx)
+ return -EAGAIN;
+ req->rl_sendctx->sc_wr.num_sge = 0;
+ req->rl_sendctx->sc_unmap_count = 0;
+ req->rl_sendctx->sc_req = req;
+ __clear_bit(RPCRDMA_REQ_F_TX_RESOURCES, &req->rl_flags);
+
+ if (!rpcrdma_prepare_hdr_sge(&r_xprt->rx_ia, req, hdrlen))
+ return -EIO;
+
+ if (rtype != rpcrdma_areadch)
+ if (!rpcrdma_prepare_msg_sges(&r_xprt->rx_ia, req, xdr, rtype))
+ return -EIO;
+
+ return 0;
+}
+
+/**
+ * rpcrdma_marshal_req - Marshal and send one RPC request
+ * @r_xprt: controlling transport
+ * @rqst: RPC request to be marshaled
+ *
+ * For the RPC in "rqst", this function:
+ * - Chooses the transfer mode (eg., RDMA_MSG or RDMA_NOMSG)
+ * - Registers Read, Write, and Reply chunks
+ * - Constructs the transport header
+ * - Posts a Send WR to send the transport header and request
+ *
+ * Returns:
+ * %0 if the RPC was sent successfully,
+ * %-ENOTCONN if the connection was lost,
+ * %-EAGAIN if the caller should call again with the same arguments,
+ * %-ENOBUFS if the caller should call again after a delay,
+ * %-EMSGSIZE if the transport header is too small,
+ * %-EIO if a permanent problem occurred while marshaling.
+ */
+int
+rpcrdma_marshal_req(struct rpcrdma_xprt *r_xprt, struct rpc_rqst *rqst)
+{
+ struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
+ struct xdr_stream *xdr = &req->rl_stream;
+ enum rpcrdma_chunktype rtype, wtype;
+ bool ddp_allowed;
+ __be32 *p;
+ int ret;
+
+ rpcrdma_set_xdrlen(&req->rl_hdrbuf, 0);
+ xdr_init_encode(xdr, &req->rl_hdrbuf,
+ req->rl_rdmabuf->rg_base);
+
+ /* Fixed header fields */
+ ret = -EMSGSIZE;
+ p = xdr_reserve_space(xdr, 4 * sizeof(*p));
+ if (!p)
+ goto out_err;
+ *p++ = rqst->rq_xid;
+ *p++ = rpcrdma_version;
+ *p++ = cpu_to_be32(r_xprt->rx_buf.rb_max_requests);
+
+ /* When the ULP employs a GSS flavor that guarantees integrity
+ * or privacy, direct data placement of individual data items
+ * is not allowed.
+ */
+ ddp_allowed = !(rqst->rq_cred->cr_auth->au_flags &
+ RPCAUTH_AUTH_DATATOUCH);
+
+ /*
+ * Chunks needed for results?
+ *
+ * o If the expected result is under the inline threshold, all ops
+ * return as inline.
+ * o Large read ops return data as write chunk(s), header as
+ * inline.
+ * o Large non-read ops return as a single reply chunk.
+ */
+ if (rpcrdma_results_inline(r_xprt, rqst))
+ wtype = rpcrdma_noch;
+ else if (ddp_allowed && rqst->rq_rcv_buf.flags & XDRBUF_READ)
+ wtype = rpcrdma_writech;
+ else
+ wtype = rpcrdma_replych;
+
+ /*
+ * Chunks needed for arguments?
+ *
+ * o If the total request is under the inline threshold, all ops
+ * are sent as inline.
+ * o Large write ops transmit data as read chunk(s), header as
+ * inline.
+ * o Large non-write ops are sent with the entire message as a
+ * single read chunk (protocol 0-position special case).
+ *
+ * This assumes that the upper layer does not present a request
+ * that both has a data payload, and whose non-data arguments
+ * by themselves are larger than the inline threshold.
+ */
+ if (rpcrdma_args_inline(r_xprt, rqst)) {
+ *p++ = rdma_msg;
+ rtype = rpcrdma_noch;
+ } else if (ddp_allowed && rqst->rq_snd_buf.flags & XDRBUF_WRITE) {
+ *p++ = rdma_msg;
+ rtype = rpcrdma_readch;
+ } else {
+ r_xprt->rx_stats.nomsg_call_count++;
+ *p++ = rdma_nomsg;
+ rtype = rpcrdma_areadch;
+ }
+
+ /* If this is a retransmit, discard previously registered
+ * chunks. Very likely the connection has been replaced,
+ * so these registrations are invalid and unusable.
+ */
+ while (unlikely(!list_empty(&req->rl_registered))) {
+ struct rpcrdma_mr *mr;
+
+ mr = rpcrdma_mr_pop(&req->rl_registered);
+ rpcrdma_mr_defer_recovery(mr);
+ }
+
+ /* This implementation supports the following combinations
+ * of chunk lists in one RPC-over-RDMA Call message:
+ *
+ * - Read list
+ * - Write list
+ * - Reply chunk
+ * - Read list + Reply chunk
+ *
+ * It might not yet support the following combinations:
+ *
+ * - Read list + Write list
+ *
+ * It does not support the following combinations:
+ *
+ * - Write list + Reply chunk
+ * - Read list + Write list + Reply chunk
+ *
+ * This implementation supports only a single chunk in each
+ * Read or Write list. Thus for example the client cannot
+ * send a Call message with a Position Zero Read chunk and a
+ * regular Read chunk at the same time.
+ */
+ if (rtype != rpcrdma_noch) {
+ ret = rpcrdma_encode_read_list(r_xprt, req, rqst, rtype);
+ if (ret)
+ goto out_err;
+ }
+ ret = encode_item_not_present(xdr);
+ if (ret)
+ goto out_err;
+
+ if (wtype == rpcrdma_writech) {
+ ret = rpcrdma_encode_write_list(r_xprt, req, rqst, wtype);
+ if (ret)
+ goto out_err;
+ }
+ ret = encode_item_not_present(xdr);
+ if (ret)
+ goto out_err;
+
+ if (wtype != rpcrdma_replych)
+ ret = encode_item_not_present(xdr);
+ else
+ ret = rpcrdma_encode_reply_chunk(r_xprt, req, rqst, wtype);
+ if (ret)
+ goto out_err;
+
+ trace_xprtrdma_marshal(rqst, xdr_stream_pos(xdr), rtype, wtype);
+
+ ret = rpcrdma_prepare_send_sges(r_xprt, req, xdr_stream_pos(xdr),
+ &rqst->rq_snd_buf, rtype);
+ if (ret)
+ goto out_err;
+ return 0;
+
+out_err:
+ switch (ret) {
+ case -EAGAIN:
+ xprt_wait_for_buffer_space(rqst->rq_task, NULL);
+ break;
+ case -ENOBUFS:
+ break;
+ default:
+ r_xprt->rx_stats.failed_marshal_count++;
+ }
+ return ret;
+}
+
+/**
+ * rpcrdma_inline_fixup - Scatter inline received data into rqst's iovecs
+ * @rqst: controlling RPC request
+ * @srcp: points to RPC message payload in receive buffer
+ * @copy_len: remaining length of receive buffer content
+ * @pad: Write chunk pad bytes needed (zero for pure inline)
+ *
+ * The upper layer has set the maximum number of bytes it can
+ * receive in each component of rq_rcv_buf. These values are set in
+ * the head.iov_len, page_len, tail.iov_len, and buflen fields.
+ *
+ * Unlike the TCP equivalent (xdr_partial_copy_from_skb), in
+ * many cases this function simply updates iov_base pointers in
+ * rq_rcv_buf to point directly to the received reply data, to
+ * avoid copying reply data.
+ *
+ * Returns the count of bytes which had to be memcopied.
+ */
+static unsigned long
+rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len, int pad)
+{
+ unsigned long fixup_copy_count;
+ int i, npages, curlen;
+ char *destp;
+ struct page **ppages;
+ int page_base;
+
+ /* The head iovec is redirected to the RPC reply message
+ * in the receive buffer, to avoid a memcopy.
+ */
+ rqst->rq_rcv_buf.head[0].iov_base = srcp;
+ rqst->rq_private_buf.head[0].iov_base = srcp;
+
+ /* The contents of the receive buffer that follow
+ * head.iov_len bytes are copied into the page list.
+ */
+ curlen = rqst->rq_rcv_buf.head[0].iov_len;
+ if (curlen > copy_len)
+ curlen = copy_len;
+ trace_xprtrdma_fixup(rqst, copy_len, curlen);
+ srcp += curlen;
+ copy_len -= curlen;
+
+ ppages = rqst->rq_rcv_buf.pages +
+ (rqst->rq_rcv_buf.page_base >> PAGE_SHIFT);
+ page_base = offset_in_page(rqst->rq_rcv_buf.page_base);
+ fixup_copy_count = 0;
+ if (copy_len && rqst->rq_rcv_buf.page_len) {
+ int pagelist_len;
+
+ pagelist_len = rqst->rq_rcv_buf.page_len;
+ if (pagelist_len > copy_len)
+ pagelist_len = copy_len;
+ npages = PAGE_ALIGN(page_base + pagelist_len) >> PAGE_SHIFT;
+ for (i = 0; i < npages; i++) {
+ curlen = PAGE_SIZE - page_base;
+ if (curlen > pagelist_len)
+ curlen = pagelist_len;
+
+ trace_xprtrdma_fixup_pg(rqst, i, srcp,
+ copy_len, curlen);
+ destp = kmap_atomic(ppages[i]);
+ memcpy(destp + page_base, srcp, curlen);
+ flush_dcache_page(ppages[i]);
+ kunmap_atomic(destp);
+ srcp += curlen;
+ copy_len -= curlen;
+ fixup_copy_count += curlen;
+ pagelist_len -= curlen;
+ if (!pagelist_len)
+ break;
+ page_base = 0;
+ }
+
+ /* Implicit padding for the last segment in a Write
+ * chunk is inserted inline at the front of the tail
+ * iovec. The upper layer ignores the content of
+ * the pad. Simply ensure inline content in the tail
+ * that follows the Write chunk is properly aligned.
+ */
+ if (pad)
+ srcp -= pad;
+ }
+
+ /* The tail iovec is redirected to the remaining data
+ * in the receive buffer, to avoid a memcopy.
+ */
+ if (copy_len || pad) {
+ rqst->rq_rcv_buf.tail[0].iov_base = srcp;
+ rqst->rq_private_buf.tail[0].iov_base = srcp;
+ }
+
+ return fixup_copy_count;
+}
+
+/* By convention, backchannel calls arrive via rdma_msg type
+ * messages, and never populate the chunk lists. This makes
+ * the RPC/RDMA header small and fixed in size, so it is
+ * straightforward to check the RPC header's direction field.
+ */
+static bool
+rpcrdma_is_bcall(struct rpcrdma_xprt *r_xprt, struct rpcrdma_rep *rep)
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+{
+ struct xdr_stream *xdr = &rep->rr_stream;
+ __be32 *p;
+
+ if (rep->rr_proc != rdma_msg)
+ return false;
+
+ /* Peek at stream contents without advancing. */
+ p = xdr_inline_decode(xdr, 0);
+
+ /* Chunk lists */
+ if (*p++ != xdr_zero)
+ return false;
+ if (*p++ != xdr_zero)
+ return false;
+ if (*p++ != xdr_zero)
+ return false;
+
+ /* RPC header */
+ if (*p++ != rep->rr_xid)
+ return false;
+ if (*p != cpu_to_be32(RPC_CALL))
+ return false;
+
+ /* Now that we are sure this is a backchannel call,
+ * advance to the RPC header.
+ */
+ p = xdr_inline_decode(xdr, 3 * sizeof(*p));
+ if (unlikely(!p))
+ goto out_short;
+
+ rpcrdma_bc_receive_call(r_xprt, rep);
+ return true;
+
+out_short:
+ pr_warn("RPC/RDMA short backward direction call\n");
+ return true;
+}
+#else /* CONFIG_SUNRPC_BACKCHANNEL */
+{
+ return false;
+}
+#endif /* CONFIG_SUNRPC_BACKCHANNEL */
+
+static int decode_rdma_segment(struct xdr_stream *xdr, u32 *length)
+{
+ u32 handle;
+ u64 offset;
+ __be32 *p;
+
+ p = xdr_inline_decode(xdr, 4 * sizeof(*p));
+ if (unlikely(!p))
+ return -EIO;
+
+ handle = be32_to_cpup(p++);
+ *length = be32_to_cpup(p++);
+ xdr_decode_hyper(p, &offset);
+
+ trace_xprtrdma_decode_seg(handle, *length, offset);
+ return 0;
+}
+
+static int decode_write_chunk(struct xdr_stream *xdr, u32 *length)
+{
+ u32 segcount, seglength;
+ __be32 *p;
+
+ p = xdr_inline_decode(xdr, sizeof(*p));
+ if (unlikely(!p))
+ return -EIO;
+
+ *length = 0;
+ segcount = be32_to_cpup(p);
+ while (segcount--) {
+ if (decode_rdma_segment(xdr, &seglength))
+ return -EIO;
+ *length += seglength;
+ }
+
+ return 0;
+}
+
+/* In RPC-over-RDMA Version One replies, a Read list is never
+ * expected. This decoder is a stub that returns an error if
+ * a Read list is present.
+ */
+static int decode_read_list(struct xdr_stream *xdr)
+{
+ __be32 *p;
+
+ p = xdr_inline_decode(xdr, sizeof(*p));
+ if (unlikely(!p))
+ return -EIO;
+ if (unlikely(*p != xdr_zero))
+ return -EIO;
+ return 0;
+}
+
+/* Supports only one Write chunk in the Write list
+ */
+static int decode_write_list(struct xdr_stream *xdr, u32 *length)
+{
+ u32 chunklen;
+ bool first;
+ __be32 *p;
+
+ *length = 0;
+ first = true;
+ do {
+ p = xdr_inline_decode(xdr, sizeof(*p));
+ if (unlikely(!p))
+ return -EIO;
+ if (*p == xdr_zero)
+ break;
+ if (!first)
+ return -EIO;
+
+ if (decode_write_chunk(xdr, &chunklen))
+ return -EIO;
+ *length += chunklen;
+ first = false;
+ } while (true);
+ return 0;
+}
+
+static int decode_reply_chunk(struct xdr_stream *xdr, u32 *length)
+{
+ __be32 *p;
+
+ p = xdr_inline_decode(xdr, sizeof(*p));
+ if (unlikely(!p))
+ return -EIO;
+
+ *length = 0;
+ if (*p != xdr_zero)
+ if (decode_write_chunk(xdr, length))
+ return -EIO;
+ return 0;
+}
+
+static int
+rpcrdma_decode_msg(struct rpcrdma_xprt *r_xprt, struct rpcrdma_rep *rep,
+ struct rpc_rqst *rqst)
+{
+ struct xdr_stream *xdr = &rep->rr_stream;
+ u32 writelist, replychunk, rpclen;
+ char *base;
+
+ /* Decode the chunk lists */
+ if (decode_read_list(xdr))
+ return -EIO;
+ if (decode_write_list(xdr, &writelist))
+ return -EIO;
+ if (decode_reply_chunk(xdr, &replychunk))
+ return -EIO;
+
+ /* RDMA_MSG sanity checks */
+ if (unlikely(replychunk))
+ return -EIO;
+
+ /* Build the RPC reply's Payload stream in rqst->rq_rcv_buf */
+ base = (char *)xdr_inline_decode(xdr, 0);
+ rpclen = xdr_stream_remaining(xdr);
+ r_xprt->rx_stats.fixup_copy_count +=
+ rpcrdma_inline_fixup(rqst, base, rpclen, writelist & 3);
+
+ r_xprt->rx_stats.total_rdma_reply += writelist;
+ return rpclen + xdr_align_size(writelist);
+}
+
+static noinline int
+rpcrdma_decode_nomsg(struct rpcrdma_xprt *r_xprt, struct rpcrdma_rep *rep)
+{
+ struct xdr_stream *xdr = &rep->rr_stream;
+ u32 writelist, replychunk;
+
+ /* Decode the chunk lists */
+ if (decode_read_list(xdr))
+ return -EIO;
+ if (decode_write_list(xdr, &writelist))
+ return -EIO;
+ if (decode_reply_chunk(xdr, &replychunk))
+ return -EIO;
+
+ /* RDMA_NOMSG sanity checks */
+ if (unlikely(writelist))
+ return -EIO;
+ if (unlikely(!replychunk))
+ return -EIO;
+
+ /* Reply chunk buffer already is the reply vector */
+ r_xprt->rx_stats.total_rdma_reply += replychunk;
+ return replychunk;
+}
+
+static noinline int
+rpcrdma_decode_error(struct rpcrdma_xprt *r_xprt, struct rpcrdma_rep *rep,
+ struct rpc_rqst *rqst)
+{
+ struct xdr_stream *xdr = &rep->rr_stream;
+ __be32 *p;
+
+ p = xdr_inline_decode(xdr, sizeof(*p));
+ if (unlikely(!p))
+ return -EIO;
+
+ switch (*p) {
+ case err_vers:
+ p = xdr_inline_decode(xdr, 2 * sizeof(*p));
+ if (!p)
+ break;
+ dprintk("RPC: %5u: %s: server reports version error (%u-%u)\n",
+ rqst->rq_task->tk_pid, __func__,
+ be32_to_cpup(p), be32_to_cpu(*(p + 1)));
+ break;
+ case err_chunk:
+ dprintk("RPC: %5u: %s: server reports header decoding error\n",
+ rqst->rq_task->tk_pid, __func__);
+ break;
+ default:
+ dprintk("RPC: %5u: %s: server reports unrecognized error %d\n",
+ rqst->rq_task->tk_pid, __func__, be32_to_cpup(p));
+ }
+
+ r_xprt->rx_stats.bad_reply_count++;
+ return -EREMOTEIO;
+}
+
+/* Perform XID lookup, reconstruction of the RPC reply, and
+ * RPC completion while holding the transport lock to ensure
+ * the rep, rqst, and rq_task pointers remain stable.
+ */
+void rpcrdma_complete_rqst(struct rpcrdma_rep *rep)
+{
+ struct rpcrdma_xprt *r_xprt = rep->rr_rxprt;
+ struct rpc_xprt *xprt = &r_xprt->rx_xprt;
+ struct rpc_rqst *rqst = rep->rr_rqst;
+ unsigned long cwnd;
+ int status;
+
+ xprt->reestablish_timeout = 0;
+
+ switch (rep->rr_proc) {
+ case rdma_msg:
+ status = rpcrdma_decode_msg(r_xprt, rep, rqst);
+ break;
+ case rdma_nomsg:
+ status = rpcrdma_decode_nomsg(r_xprt, rep);
+ break;
+ case rdma_error:
+ status = rpcrdma_decode_error(r_xprt, rep, rqst);
+ break;
+ default:
+ status = -EIO;
+ }
+ if (status < 0)
+ goto out_badheader;
+
+out:
+ spin_lock(&xprt->recv_lock);
+ cwnd = xprt->cwnd;
+ xprt->cwnd = r_xprt->rx_buf.rb_credits << RPC_CWNDSHIFT;
+ if (xprt->cwnd > cwnd)
+ xprt_release_rqst_cong(rqst->rq_task);
+
+ xprt_complete_rqst(rqst->rq_task, status);
+ xprt_unpin_rqst(rqst);
+ spin_unlock(&xprt->recv_lock);
+ return;
+
+/* If the incoming reply terminated a pending RPC, the next
+ * RPC call will post a replacement receive buffer as it is
+ * being marshaled.
+ */
+out_badheader:
+ trace_xprtrdma_reply_hdr(rep);
+ r_xprt->rx_stats.bad_reply_count++;
+ status = -EIO;
+ goto out;
+}
+
+void rpcrdma_release_rqst(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
+{
+ /* Invalidate and unmap the data payloads before waking
+ * the waiting application. This guarantees the memory
+ * regions are properly fenced from the server before the
+ * application accesses the data. It also ensures proper
+ * send flow control: waking the next RPC waits until this
+ * RPC has relinquished all its Send Queue entries.
+ */
+ if (!list_empty(&req->rl_registered))
+ r_xprt->rx_ia.ri_ops->ro_unmap_sync(r_xprt,
+ &req->rl_registered);
+
+ /* Ensure that any DMA mapped pages associated with
+ * the Send of the RPC Call have been unmapped before
+ * allowing the RPC to complete. This protects argument
+ * memory not controlled by the RPC client from being
+ * re-used before we're done with it.
+ */
+ if (test_bit(RPCRDMA_REQ_F_TX_RESOURCES, &req->rl_flags)) {
+ r_xprt->rx_stats.reply_waits_for_send++;
+ out_of_line_wait_on_bit(&req->rl_flags,
+ RPCRDMA_REQ_F_TX_RESOURCES,
+ bit_wait,
+ TASK_UNINTERRUPTIBLE);
+ }
+}
+
+/* Reply handling runs in the poll worker thread. Anything that
+ * might wait is deferred to a separate workqueue.
+ */
+void rpcrdma_deferred_completion(struct work_struct *work)
+{
+ struct rpcrdma_rep *rep =
+ container_of(work, struct rpcrdma_rep, rr_work);
+ struct rpcrdma_req *req = rpcr_to_rdmar(rep->rr_rqst);
+ struct rpcrdma_xprt *r_xprt = rep->rr_rxprt;
+
+ trace_xprtrdma_defer_cmp(rep);
+ if (rep->rr_wc_flags & IB_WC_WITH_INVALIDATE)
+ r_xprt->rx_ia.ri_ops->ro_reminv(rep, &req->rl_registered);
+ rpcrdma_release_rqst(r_xprt, req);
+ rpcrdma_complete_rqst(rep);
+}
+
+/* Process received RPC/RDMA messages.
+ *
+ * Errors must result in the RPC task either being awakened, or
+ * allowed to timeout, to discover the errors at that time.
+ */
+void rpcrdma_reply_handler(struct rpcrdma_rep *rep)
+{
+ struct rpcrdma_xprt *r_xprt = rep->rr_rxprt;
+ struct rpc_xprt *xprt = &r_xprt->rx_xprt;
+ struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+ struct rpcrdma_req *req;
+ struct rpc_rqst *rqst;
+ u32 credits;
+ __be32 *p;
+
+ --buf->rb_posted_receives;
+
+ if (rep->rr_hdrbuf.head[0].iov_len == 0)
+ goto out_badstatus;
+
+ /* Fixed transport header fields */
+ xdr_init_decode(&rep->rr_stream, &rep->rr_hdrbuf,
+ rep->rr_hdrbuf.head[0].iov_base);
+ p = xdr_inline_decode(&rep->rr_stream, 4 * sizeof(*p));
+ if (unlikely(!p))
+ goto out_shortreply;
+ rep->rr_xid = *p++;
+ rep->rr_vers = *p++;
+ credits = be32_to_cpu(*p++);
+ rep->rr_proc = *p++;
+
+ if (rep->rr_vers != rpcrdma_version)
+ goto out_badversion;
+
+ if (rpcrdma_is_bcall(r_xprt, rep))
+ return;
+
+ /* Match incoming rpcrdma_rep to an rpcrdma_req to
+ * get context for handling any incoming chunks.
+ */
+ spin_lock(&xprt->recv_lock);
+ rqst = xprt_lookup_rqst(xprt, rep->rr_xid);
+ if (!rqst)
+ goto out_norqst;
+ xprt_pin_rqst(rqst);
+
+ if (credits == 0)
+ credits = 1; /* don't deadlock */
+ else if (credits > buf->rb_max_requests)
+ credits = buf->rb_max_requests;
+ buf->rb_credits = credits;
+
+ spin_unlock(&xprt->recv_lock);
+
+ req = rpcr_to_rdmar(rqst);
+ req->rl_reply = rep;
+ rep->rr_rqst = rqst;
+ clear_bit(RPCRDMA_REQ_F_PENDING, &req->rl_flags);
+
+ trace_xprtrdma_reply(rqst->rq_task, rep, req, credits);
+
+ rpcrdma_post_recvs(r_xprt, false);
+ queue_work(rpcrdma_receive_wq, &rep->rr_work);
+ return;
+
+out_badversion:
+ trace_xprtrdma_reply_vers(rep);
+ goto repost;
+
+/* The RPC transaction has already been terminated, or the header
+ * is corrupt.
+ */
+out_norqst:
+ spin_unlock(&xprt->recv_lock);
+ trace_xprtrdma_reply_rqst(rep);
+ goto repost;
+
+out_shortreply:
+ trace_xprtrdma_reply_short(rep);
+
+/* If no pending RPC transaction was matched, post a replacement
+ * receive buffer before returning.
+ */
+repost:
+ rpcrdma_post_recvs(r_xprt, false);
+out_badstatus:
+ rpcrdma_recv_buffer_put(rep);
+}