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diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
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+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
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+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * Copyright (c) 2016-2018 Oracle. All rights reserved.
+ * Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved.
+ * Copyright (c) 2005-2006 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.
+ *
+ * Author: Tom Tucker <tom@opengridcomputing.com>
+ */
+
+/* Operation
+ *
+ * The main entry point is svc_rdma_sendto. This is called by the
+ * RPC server when an RPC Reply is ready to be transmitted to a client.
+ *
+ * The passed-in svc_rqst contains a struct xdr_buf which holds an
+ * XDR-encoded RPC Reply message. sendto must construct the RPC-over-RDMA
+ * transport header, post all Write WRs needed for this Reply, then post
+ * a Send WR conveying the transport header and the RPC message itself to
+ * the client.
+ *
+ * svc_rdma_sendto must fully transmit the Reply before returning, as
+ * the svc_rqst will be recycled as soon as sendto returns. Remaining
+ * resources referred to by the svc_rqst are also recycled at that time.
+ * Therefore any resources that must remain longer must be detached
+ * from the svc_rqst and released later.
+ *
+ * Page Management
+ *
+ * The I/O that performs Reply transmission is asynchronous, and may
+ * complete well after sendto returns. Thus pages under I/O must be
+ * removed from the svc_rqst before sendto returns.
+ *
+ * The logic here depends on Send Queue and completion ordering. Since
+ * the Send WR is always posted last, it will always complete last. Thus
+ * when it completes, it is guaranteed that all previous Write WRs have
+ * also completed.
+ *
+ * Write WRs are constructed and posted. Each Write segment gets its own
+ * svc_rdma_rw_ctxt, allowing the Write completion handler to find and
+ * DMA-unmap the pages under I/O for that Write segment. The Write
+ * completion handler does not release any pages.
+ *
+ * When the Send WR is constructed, it also gets its own svc_rdma_send_ctxt.
+ * The ownership of all of the Reply's pages are transferred into that
+ * ctxt, the Send WR is posted, and sendto returns.
+ *
+ * The svc_rdma_send_ctxt is presented when the Send WR completes. The
+ * Send completion handler finally releases the Reply's pages.
+ *
+ * This mechanism also assumes that completions on the transport's Send
+ * Completion Queue do not run in parallel. Otherwise a Write completion
+ * and Send completion running at the same time could release pages that
+ * are still DMA-mapped.
+ *
+ * Error Handling
+ *
+ * - If the Send WR is posted successfully, it will either complete
+ * successfully, or get flushed. Either way, the Send completion
+ * handler releases the Reply's pages.
+ * - If the Send WR cannot be not posted, the forward path releases
+ * the Reply's pages.
+ *
+ * This handles the case, without the use of page reference counting,
+ * where two different Write segments send portions of the same page.
+ */
+
+#include <linux/spinlock.h>
+#include <asm/unaligned.h>
+
+#include <rdma/ib_verbs.h>
+#include <rdma/rdma_cm.h>
+
+#include <linux/sunrpc/debug.h>
+#include <linux/sunrpc/svc_rdma.h>
+
+#include "xprt_rdma.h"
+#include <trace/events/rpcrdma.h>
+
+static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc);
+
+static void svc_rdma_send_cid_init(struct svcxprt_rdma *rdma,
+ struct rpc_rdma_cid *cid)
+{
+ cid->ci_queue_id = rdma->sc_sq_cq->res.id;
+ cid->ci_completion_id = atomic_inc_return(&rdma->sc_completion_ids);
+}
+
+static struct svc_rdma_send_ctxt *
+svc_rdma_send_ctxt_alloc(struct svcxprt_rdma *rdma)
+{
+ struct svc_rdma_send_ctxt *ctxt;
+ dma_addr_t addr;
+ void *buffer;
+ size_t size;
+ int i;
+
+ size = sizeof(*ctxt);
+ size += rdma->sc_max_send_sges * sizeof(struct ib_sge);
+ ctxt = kmalloc(size, GFP_KERNEL);
+ if (!ctxt)
+ goto fail0;
+ buffer = kmalloc(rdma->sc_max_req_size, GFP_KERNEL);
+ if (!buffer)
+ goto fail1;
+ addr = ib_dma_map_single(rdma->sc_pd->device, buffer,
+ rdma->sc_max_req_size, DMA_TO_DEVICE);
+ if (ib_dma_mapping_error(rdma->sc_pd->device, addr))
+ goto fail2;
+
+ svc_rdma_send_cid_init(rdma, &ctxt->sc_cid);
+
+ ctxt->sc_send_wr.next = NULL;
+ ctxt->sc_send_wr.wr_cqe = &ctxt->sc_cqe;
+ ctxt->sc_send_wr.sg_list = ctxt->sc_sges;
+ ctxt->sc_send_wr.send_flags = IB_SEND_SIGNALED;
+ init_completion(&ctxt->sc_done);
+ ctxt->sc_cqe.done = svc_rdma_wc_send;
+ ctxt->sc_xprt_buf = buffer;
+ xdr_buf_init(&ctxt->sc_hdrbuf, ctxt->sc_xprt_buf,
+ rdma->sc_max_req_size);
+ ctxt->sc_sges[0].addr = addr;
+
+ for (i = 0; i < rdma->sc_max_send_sges; i++)
+ ctxt->sc_sges[i].lkey = rdma->sc_pd->local_dma_lkey;
+ return ctxt;
+
+fail2:
+ kfree(buffer);
+fail1:
+ kfree(ctxt);
+fail0:
+ return NULL;
+}
+
+/**
+ * svc_rdma_send_ctxts_destroy - Release all send_ctxt's for an xprt
+ * @rdma: svcxprt_rdma being torn down
+ *
+ */
+void svc_rdma_send_ctxts_destroy(struct svcxprt_rdma *rdma)
+{
+ struct svc_rdma_send_ctxt *ctxt;
+ struct llist_node *node;
+
+ while ((node = llist_del_first(&rdma->sc_send_ctxts)) != NULL) {
+ ctxt = llist_entry(node, struct svc_rdma_send_ctxt, sc_node);
+ ib_dma_unmap_single(rdma->sc_pd->device,
+ ctxt->sc_sges[0].addr,
+ rdma->sc_max_req_size,
+ DMA_TO_DEVICE);
+ kfree(ctxt->sc_xprt_buf);
+ kfree(ctxt);
+ }
+}
+
+/**
+ * svc_rdma_send_ctxt_get - Get a free send_ctxt
+ * @rdma: controlling svcxprt_rdma
+ *
+ * Returns a ready-to-use send_ctxt, or NULL if none are
+ * available and a fresh one cannot be allocated.
+ */
+struct svc_rdma_send_ctxt *svc_rdma_send_ctxt_get(struct svcxprt_rdma *rdma)
+{
+ struct svc_rdma_send_ctxt *ctxt;
+ struct llist_node *node;
+
+ spin_lock(&rdma->sc_send_lock);
+ node = llist_del_first(&rdma->sc_send_ctxts);
+ if (!node)
+ goto out_empty;
+ ctxt = llist_entry(node, struct svc_rdma_send_ctxt, sc_node);
+ spin_unlock(&rdma->sc_send_lock);
+
+out:
+ rpcrdma_set_xdrlen(&ctxt->sc_hdrbuf, 0);
+ xdr_init_encode(&ctxt->sc_stream, &ctxt->sc_hdrbuf,
+ ctxt->sc_xprt_buf, NULL);
+
+ ctxt->sc_send_wr.num_sge = 0;
+ ctxt->sc_cur_sge_no = 0;
+ return ctxt;
+
+out_empty:
+ spin_unlock(&rdma->sc_send_lock);
+ ctxt = svc_rdma_send_ctxt_alloc(rdma);
+ if (!ctxt)
+ return NULL;
+ goto out;
+}
+
+/**
+ * svc_rdma_send_ctxt_put - Return send_ctxt to free list
+ * @rdma: controlling svcxprt_rdma
+ * @ctxt: object to return to the free list
+ */
+void svc_rdma_send_ctxt_put(struct svcxprt_rdma *rdma,
+ struct svc_rdma_send_ctxt *ctxt)
+{
+ struct ib_device *device = rdma->sc_cm_id->device;
+ unsigned int i;
+
+ /* The first SGE contains the transport header, which
+ * remains mapped until @ctxt is destroyed.
+ */
+ for (i = 1; i < ctxt->sc_send_wr.num_sge; i++) {
+ ib_dma_unmap_page(device,
+ ctxt->sc_sges[i].addr,
+ ctxt->sc_sges[i].length,
+ DMA_TO_DEVICE);
+ trace_svcrdma_dma_unmap_page(rdma,
+ ctxt->sc_sges[i].addr,
+ ctxt->sc_sges[i].length);
+ }
+
+ llist_add(&ctxt->sc_node, &rdma->sc_send_ctxts);
+}
+
+/**
+ * svc_rdma_wake_send_waiters - manage Send Queue accounting
+ * @rdma: controlling transport
+ * @avail: Number of additional SQEs that are now available
+ *
+ */
+void svc_rdma_wake_send_waiters(struct svcxprt_rdma *rdma, int avail)
+{
+ atomic_add(avail, &rdma->sc_sq_avail);
+ smp_mb__after_atomic();
+ if (unlikely(waitqueue_active(&rdma->sc_send_wait)))
+ wake_up(&rdma->sc_send_wait);
+}
+
+/**
+ * svc_rdma_wc_send - Invoked by RDMA provider for each polled Send WC
+ * @cq: Completion Queue context
+ * @wc: Work Completion object
+ *
+ * NB: The svc_xprt/svcxprt_rdma is pinned whenever it's possible that
+ * the Send completion handler could be running.
+ */
+static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc)
+{
+ struct svcxprt_rdma *rdma = cq->cq_context;
+ struct ib_cqe *cqe = wc->wr_cqe;
+ struct svc_rdma_send_ctxt *ctxt =
+ container_of(cqe, struct svc_rdma_send_ctxt, sc_cqe);
+
+ svc_rdma_wake_send_waiters(rdma, 1);
+ complete(&ctxt->sc_done);
+
+ if (unlikely(wc->status != IB_WC_SUCCESS))
+ goto flushed;
+
+ trace_svcrdma_wc_send(wc, &ctxt->sc_cid);
+ return;
+
+flushed:
+ if (wc->status != IB_WC_WR_FLUSH_ERR)
+ trace_svcrdma_wc_send_err(wc, &ctxt->sc_cid);
+ else
+ trace_svcrdma_wc_send_flush(wc, &ctxt->sc_cid);
+ svc_xprt_deferred_close(&rdma->sc_xprt);
+}
+
+/**
+ * svc_rdma_send - Post a single Send WR
+ * @rdma: transport on which to post the WR
+ * @ctxt: send ctxt with a Send WR ready to post
+ *
+ * Returns zero if the Send WR was posted successfully. Otherwise, a
+ * negative errno is returned.
+ */
+int svc_rdma_send(struct svcxprt_rdma *rdma, struct svc_rdma_send_ctxt *ctxt)
+{
+ struct ib_send_wr *wr = &ctxt->sc_send_wr;
+ int ret;
+
+ reinit_completion(&ctxt->sc_done);
+
+ /* Sync the transport header buffer */
+ ib_dma_sync_single_for_device(rdma->sc_pd->device,
+ wr->sg_list[0].addr,
+ wr->sg_list[0].length,
+ DMA_TO_DEVICE);
+
+ /* If the SQ is full, wait until an SQ entry is available */
+ while (1) {
+ if ((atomic_dec_return(&rdma->sc_sq_avail) < 0)) {
+ percpu_counter_inc(&svcrdma_stat_sq_starve);
+ trace_svcrdma_sq_full(rdma);
+ atomic_inc(&rdma->sc_sq_avail);
+ wait_event(rdma->sc_send_wait,
+ atomic_read(&rdma->sc_sq_avail) > 1);
+ if (test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags))
+ return -ENOTCONN;
+ trace_svcrdma_sq_retry(rdma);
+ continue;
+ }
+
+ trace_svcrdma_post_send(ctxt);
+ ret = ib_post_send(rdma->sc_qp, wr, NULL);
+ if (ret)
+ break;
+ return 0;
+ }
+
+ trace_svcrdma_sq_post_err(rdma, ret);
+ svc_xprt_deferred_close(&rdma->sc_xprt);
+ wake_up(&rdma->sc_send_wait);
+ return ret;
+}
+
+/**
+ * svc_rdma_encode_read_list - Encode RPC Reply's Read chunk list
+ * @sctxt: Send context for the RPC Reply
+ *
+ * Return values:
+ * On success, returns length in bytes of the Reply XDR buffer
+ * that was consumed by the Reply Read list
+ * %-EMSGSIZE on XDR buffer overflow
+ */
+static ssize_t svc_rdma_encode_read_list(struct svc_rdma_send_ctxt *sctxt)
+{
+ /* RPC-over-RDMA version 1 replies never have a Read list. */
+ return xdr_stream_encode_item_absent(&sctxt->sc_stream);
+}
+
+/**
+ * svc_rdma_encode_write_segment - Encode one Write segment
+ * @sctxt: Send context for the RPC Reply
+ * @chunk: Write chunk to push
+ * @remaining: remaining bytes of the payload left in the Write chunk
+ * @segno: which segment in the chunk
+ *
+ * Return values:
+ * On success, returns length in bytes of the Reply XDR buffer
+ * that was consumed by the Write segment, and updates @remaining
+ * %-EMSGSIZE on XDR buffer overflow
+ */
+static ssize_t svc_rdma_encode_write_segment(struct svc_rdma_send_ctxt *sctxt,
+ const struct svc_rdma_chunk *chunk,
+ u32 *remaining, unsigned int segno)
+{
+ const struct svc_rdma_segment *segment = &chunk->ch_segments[segno];
+ const size_t len = rpcrdma_segment_maxsz * sizeof(__be32);
+ u32 length;
+ __be32 *p;
+
+ p = xdr_reserve_space(&sctxt->sc_stream, len);
+ if (!p)
+ return -EMSGSIZE;
+
+ length = min_t(u32, *remaining, segment->rs_length);
+ *remaining -= length;
+ xdr_encode_rdma_segment(p, segment->rs_handle, length,
+ segment->rs_offset);
+ trace_svcrdma_encode_wseg(sctxt, segno, segment->rs_handle, length,
+ segment->rs_offset);
+ return len;
+}
+
+/**
+ * svc_rdma_encode_write_chunk - Encode one Write chunk
+ * @sctxt: Send context for the RPC Reply
+ * @chunk: Write chunk to push
+ *
+ * Copy a Write chunk from the Call transport header to the
+ * Reply transport header. Update each segment's length field
+ * to reflect the number of bytes written in that segment.
+ *
+ * Return values:
+ * On success, returns length in bytes of the Reply XDR buffer
+ * that was consumed by the Write chunk
+ * %-EMSGSIZE on XDR buffer overflow
+ */
+static ssize_t svc_rdma_encode_write_chunk(struct svc_rdma_send_ctxt *sctxt,
+ const struct svc_rdma_chunk *chunk)
+{
+ u32 remaining = chunk->ch_payload_length;
+ unsigned int segno;
+ ssize_t len, ret;
+
+ len = 0;
+ ret = xdr_stream_encode_item_present(&sctxt->sc_stream);
+ if (ret < 0)
+ return ret;
+ len += ret;
+
+ ret = xdr_stream_encode_u32(&sctxt->sc_stream, chunk->ch_segcount);
+ if (ret < 0)
+ return ret;
+ len += ret;
+
+ for (segno = 0; segno < chunk->ch_segcount; segno++) {
+ ret = svc_rdma_encode_write_segment(sctxt, chunk, &remaining, segno);
+ if (ret < 0)
+ return ret;
+ len += ret;
+ }
+
+ return len;
+}
+
+/**
+ * svc_rdma_encode_write_list - Encode RPC Reply's Write chunk list
+ * @rctxt: Reply context with information about the RPC Call
+ * @sctxt: Send context for the RPC Reply
+ *
+ * Return values:
+ * On success, returns length in bytes of the Reply XDR buffer
+ * that was consumed by the Reply's Write list
+ * %-EMSGSIZE on XDR buffer overflow
+ */
+static ssize_t svc_rdma_encode_write_list(struct svc_rdma_recv_ctxt *rctxt,
+ struct svc_rdma_send_ctxt *sctxt)
+{
+ struct svc_rdma_chunk *chunk;
+ ssize_t len, ret;
+
+ len = 0;
+ pcl_for_each_chunk(chunk, &rctxt->rc_write_pcl) {
+ ret = svc_rdma_encode_write_chunk(sctxt, chunk);
+ if (ret < 0)
+ return ret;
+ len += ret;
+ }
+
+ /* Terminate the Write list */
+ ret = xdr_stream_encode_item_absent(&sctxt->sc_stream);
+ if (ret < 0)
+ return ret;
+
+ return len + ret;
+}
+
+/**
+ * svc_rdma_encode_reply_chunk - Encode RPC Reply's Reply chunk
+ * @rctxt: Reply context with information about the RPC Call
+ * @sctxt: Send context for the RPC Reply
+ * @length: size in bytes of the payload in the Reply chunk
+ *
+ * Return values:
+ * On success, returns length in bytes of the Reply XDR buffer
+ * that was consumed by the Reply's Reply chunk
+ * %-EMSGSIZE on XDR buffer overflow
+ * %-E2BIG if the RPC message is larger than the Reply chunk
+ */
+static ssize_t
+svc_rdma_encode_reply_chunk(struct svc_rdma_recv_ctxt *rctxt,
+ struct svc_rdma_send_ctxt *sctxt,
+ unsigned int length)
+{
+ struct svc_rdma_chunk *chunk;
+
+ if (pcl_is_empty(&rctxt->rc_reply_pcl))
+ return xdr_stream_encode_item_absent(&sctxt->sc_stream);
+
+ chunk = pcl_first_chunk(&rctxt->rc_reply_pcl);
+ if (length > chunk->ch_length)
+ return -E2BIG;
+
+ chunk->ch_payload_length = length;
+ return svc_rdma_encode_write_chunk(sctxt, chunk);
+}
+
+struct svc_rdma_map_data {
+ struct svcxprt_rdma *md_rdma;
+ struct svc_rdma_send_ctxt *md_ctxt;
+};
+
+/**
+ * svc_rdma_page_dma_map - DMA map one page
+ * @data: pointer to arguments
+ * @page: struct page to DMA map
+ * @offset: offset into the page
+ * @len: number of bytes to map
+ *
+ * Returns:
+ * %0 if DMA mapping was successful
+ * %-EIO if the page cannot be DMA mapped
+ */
+static int svc_rdma_page_dma_map(void *data, struct page *page,
+ unsigned long offset, unsigned int len)
+{
+ struct svc_rdma_map_data *args = data;
+ struct svcxprt_rdma *rdma = args->md_rdma;
+ struct svc_rdma_send_ctxt *ctxt = args->md_ctxt;
+ struct ib_device *dev = rdma->sc_cm_id->device;
+ dma_addr_t dma_addr;
+
+ ++ctxt->sc_cur_sge_no;
+
+ dma_addr = ib_dma_map_page(dev, page, offset, len, DMA_TO_DEVICE);
+ if (ib_dma_mapping_error(dev, dma_addr))
+ goto out_maperr;
+
+ trace_svcrdma_dma_map_page(rdma, dma_addr, len);
+ ctxt->sc_sges[ctxt->sc_cur_sge_no].addr = dma_addr;
+ ctxt->sc_sges[ctxt->sc_cur_sge_no].length = len;
+ ctxt->sc_send_wr.num_sge++;
+ return 0;
+
+out_maperr:
+ trace_svcrdma_dma_map_err(rdma, dma_addr, len);
+ return -EIO;
+}
+
+/**
+ * svc_rdma_iov_dma_map - DMA map an iovec
+ * @data: pointer to arguments
+ * @iov: kvec to DMA map
+ *
+ * ib_dma_map_page() is used here because svc_rdma_dma_unmap()
+ * handles DMA-unmap and it uses ib_dma_unmap_page() exclusively.
+ *
+ * Returns:
+ * %0 if DMA mapping was successful
+ * %-EIO if the iovec cannot be DMA mapped
+ */
+static int svc_rdma_iov_dma_map(void *data, const struct kvec *iov)
+{
+ if (!iov->iov_len)
+ return 0;
+ return svc_rdma_page_dma_map(data, virt_to_page(iov->iov_base),
+ offset_in_page(iov->iov_base),
+ iov->iov_len);
+}
+
+/**
+ * svc_rdma_xb_dma_map - DMA map all segments of an xdr_buf
+ * @xdr: xdr_buf containing portion of an RPC message to transmit
+ * @data: pointer to arguments
+ *
+ * Returns:
+ * %0 if DMA mapping was successful
+ * %-EIO if DMA mapping failed
+ *
+ * On failure, any DMA mappings that have been already done must be
+ * unmapped by the caller.
+ */
+static int svc_rdma_xb_dma_map(const struct xdr_buf *xdr, void *data)
+{
+ unsigned int len, remaining;
+ unsigned long pageoff;
+ struct page **ppages;
+ int ret;
+
+ ret = svc_rdma_iov_dma_map(data, &xdr->head[0]);
+ if (ret < 0)
+ return ret;
+
+ ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
+ pageoff = offset_in_page(xdr->page_base);
+ remaining = xdr->page_len;
+ while (remaining) {
+ len = min_t(u32, PAGE_SIZE - pageoff, remaining);
+
+ ret = svc_rdma_page_dma_map(data, *ppages++, pageoff, len);
+ if (ret < 0)
+ return ret;
+
+ remaining -= len;
+ pageoff = 0;
+ }
+
+ ret = svc_rdma_iov_dma_map(data, &xdr->tail[0]);
+ if (ret < 0)
+ return ret;
+
+ return xdr->len;
+}
+
+struct svc_rdma_pullup_data {
+ u8 *pd_dest;
+ unsigned int pd_length;
+ unsigned int pd_num_sges;
+};
+
+/**
+ * svc_rdma_xb_count_sges - Count how many SGEs will be needed
+ * @xdr: xdr_buf containing portion of an RPC message to transmit
+ * @data: pointer to arguments
+ *
+ * Returns:
+ * Number of SGEs needed to Send the contents of @xdr inline
+ */
+static int svc_rdma_xb_count_sges(const struct xdr_buf *xdr,
+ void *data)
+{
+ struct svc_rdma_pullup_data *args = data;
+ unsigned int remaining;
+ unsigned long offset;
+
+ if (xdr->head[0].iov_len)
+ ++args->pd_num_sges;
+
+ offset = offset_in_page(xdr->page_base);
+ remaining = xdr->page_len;
+ while (remaining) {
+ ++args->pd_num_sges;
+ remaining -= min_t(u32, PAGE_SIZE - offset, remaining);
+ offset = 0;
+ }
+
+ if (xdr->tail[0].iov_len)
+ ++args->pd_num_sges;
+
+ args->pd_length += xdr->len;
+ return 0;
+}
+
+/**
+ * svc_rdma_pull_up_needed - Determine whether to use pull-up
+ * @rdma: controlling transport
+ * @sctxt: send_ctxt for the Send WR
+ * @rctxt: Write and Reply chunks provided by client
+ * @xdr: xdr_buf containing RPC message to transmit
+ *
+ * Returns:
+ * %true if pull-up must be used
+ * %false otherwise
+ */
+static bool svc_rdma_pull_up_needed(const struct svcxprt_rdma *rdma,
+ const struct svc_rdma_send_ctxt *sctxt,
+ const struct svc_rdma_recv_ctxt *rctxt,
+ const struct xdr_buf *xdr)
+{
+ /* Resources needed for the transport header */
+ struct svc_rdma_pullup_data args = {
+ .pd_length = sctxt->sc_hdrbuf.len,
+ .pd_num_sges = 1,
+ };
+ int ret;
+
+ ret = pcl_process_nonpayloads(&rctxt->rc_write_pcl, xdr,
+ svc_rdma_xb_count_sges, &args);
+ if (ret < 0)
+ return false;
+
+ if (args.pd_length < RPCRDMA_PULLUP_THRESH)
+ return true;
+ return args.pd_num_sges >= rdma->sc_max_send_sges;
+}
+
+/**
+ * svc_rdma_xb_linearize - Copy region of xdr_buf to flat buffer
+ * @xdr: xdr_buf containing portion of an RPC message to copy
+ * @data: pointer to arguments
+ *
+ * Returns:
+ * Always zero.
+ */
+static int svc_rdma_xb_linearize(const struct xdr_buf *xdr,
+ void *data)
+{
+ struct svc_rdma_pullup_data *args = data;
+ unsigned int len, remaining;
+ unsigned long pageoff;
+ struct page **ppages;
+
+ if (xdr->head[0].iov_len) {
+ memcpy(args->pd_dest, xdr->head[0].iov_base, xdr->head[0].iov_len);
+ args->pd_dest += xdr->head[0].iov_len;
+ }
+
+ ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
+ pageoff = offset_in_page(xdr->page_base);
+ remaining = xdr->page_len;
+ while (remaining) {
+ len = min_t(u32, PAGE_SIZE - pageoff, remaining);
+ memcpy(args->pd_dest, page_address(*ppages) + pageoff, len);
+ remaining -= len;
+ args->pd_dest += len;
+ pageoff = 0;
+ ppages++;
+ }
+
+ if (xdr->tail[0].iov_len) {
+ memcpy(args->pd_dest, xdr->tail[0].iov_base, xdr->tail[0].iov_len);
+ args->pd_dest += xdr->tail[0].iov_len;
+ }
+
+ args->pd_length += xdr->len;
+ return 0;
+}
+
+/**
+ * svc_rdma_pull_up_reply_msg - Copy Reply into a single buffer
+ * @rdma: controlling transport
+ * @sctxt: send_ctxt for the Send WR; xprt hdr is already prepared
+ * @rctxt: Write and Reply chunks provided by client
+ * @xdr: prepared xdr_buf containing RPC message
+ *
+ * The device is not capable of sending the reply directly.
+ * Assemble the elements of @xdr into the transport header buffer.
+ *
+ * Assumptions:
+ * pull_up_needed has determined that @xdr will fit in the buffer.
+ *
+ * Returns:
+ * %0 if pull-up was successful
+ * %-EMSGSIZE if a buffer manipulation problem occurred
+ */
+static int svc_rdma_pull_up_reply_msg(const struct svcxprt_rdma *rdma,
+ struct svc_rdma_send_ctxt *sctxt,
+ const struct svc_rdma_recv_ctxt *rctxt,
+ const struct xdr_buf *xdr)
+{
+ struct svc_rdma_pullup_data args = {
+ .pd_dest = sctxt->sc_xprt_buf + sctxt->sc_hdrbuf.len,
+ };
+ int ret;
+
+ ret = pcl_process_nonpayloads(&rctxt->rc_write_pcl, xdr,
+ svc_rdma_xb_linearize, &args);
+ if (ret < 0)
+ return ret;
+
+ sctxt->sc_sges[0].length = sctxt->sc_hdrbuf.len + args.pd_length;
+ trace_svcrdma_send_pullup(sctxt, args.pd_length);
+ return 0;
+}
+
+/* svc_rdma_map_reply_msg - DMA map the buffer holding RPC message
+ * @rdma: controlling transport
+ * @sctxt: send_ctxt for the Send WR
+ * @rctxt: Write and Reply chunks provided by client
+ * @xdr: prepared xdr_buf containing RPC message
+ *
+ * Returns:
+ * %0 if DMA mapping was successful.
+ * %-EMSGSIZE if a buffer manipulation problem occurred
+ * %-EIO if DMA mapping failed
+ *
+ * The Send WR's num_sge field is set in all cases.
+ */
+int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma,
+ struct svc_rdma_send_ctxt *sctxt,
+ const struct svc_rdma_recv_ctxt *rctxt,
+ const struct xdr_buf *xdr)
+{
+ struct svc_rdma_map_data args = {
+ .md_rdma = rdma,
+ .md_ctxt = sctxt,
+ };
+
+ /* Set up the (persistently-mapped) transport header SGE. */
+ sctxt->sc_send_wr.num_sge = 1;
+ sctxt->sc_sges[0].length = sctxt->sc_hdrbuf.len;
+
+ /* If there is a Reply chunk, nothing follows the transport
+ * header, and we're done here.
+ */
+ if (!pcl_is_empty(&rctxt->rc_reply_pcl))
+ return 0;
+
+ /* For pull-up, svc_rdma_send() will sync the transport header.
+ * No additional DMA mapping is necessary.
+ */
+ if (svc_rdma_pull_up_needed(rdma, sctxt, rctxt, xdr))
+ return svc_rdma_pull_up_reply_msg(rdma, sctxt, rctxt, xdr);
+
+ return pcl_process_nonpayloads(&rctxt->rc_write_pcl, xdr,
+ svc_rdma_xb_dma_map, &args);
+}
+
+/* Prepare the portion of the RPC Reply that will be transmitted
+ * via RDMA Send. The RPC-over-RDMA transport header is prepared
+ * in sc_sges[0], and the RPC xdr_buf is prepared in following sges.
+ *
+ * Depending on whether a Write list or Reply chunk is present,
+ * the server may send all, a portion of, or none of the xdr_buf.
+ * In the latter case, only the transport header (sc_sges[0]) is
+ * transmitted.
+ *
+ * RDMA Send is the last step of transmitting an RPC reply. Pages
+ * involved in the earlier RDMA Writes are here transferred out
+ * of the rqstp and into the sctxt's page array. These pages are
+ * DMA unmapped by each Write completion, but the subsequent Send
+ * completion finally releases these pages.
+ *
+ * Assumptions:
+ * - The Reply's transport header will never be larger than a page.
+ */
+static int svc_rdma_send_reply_msg(struct svcxprt_rdma *rdma,
+ struct svc_rdma_send_ctxt *sctxt,
+ const struct svc_rdma_recv_ctxt *rctxt,
+ struct svc_rqst *rqstp)
+{
+ int ret;
+
+ ret = svc_rdma_map_reply_msg(rdma, sctxt, rctxt, &rqstp->rq_res);
+ if (ret < 0)
+ return ret;
+
+ if (rctxt->rc_inv_rkey) {
+ sctxt->sc_send_wr.opcode = IB_WR_SEND_WITH_INV;
+ sctxt->sc_send_wr.ex.invalidate_rkey = rctxt->rc_inv_rkey;
+ } else {
+ sctxt->sc_send_wr.opcode = IB_WR_SEND;
+ }
+
+ ret = svc_rdma_send(rdma, sctxt);
+ if (ret < 0)
+ return ret;
+
+ ret = wait_for_completion_killable(&sctxt->sc_done);
+ svc_rdma_send_ctxt_put(rdma, sctxt);
+ return ret;
+}
+
+/**
+ * svc_rdma_send_error_msg - Send an RPC/RDMA v1 error response
+ * @rdma: controlling transport context
+ * @sctxt: Send context for the response
+ * @rctxt: Receive context for incoming bad message
+ * @status: negative errno indicating error that occurred
+ *
+ * Given the client-provided Read, Write, and Reply chunks, the
+ * server was not able to parse the Call or form a complete Reply.
+ * Return an RDMA_ERROR message so the client can retire the RPC
+ * transaction.
+ *
+ * The caller does not have to release @sctxt. It is released by
+ * Send completion, or by this function on error.
+ */
+void svc_rdma_send_error_msg(struct svcxprt_rdma *rdma,
+ struct svc_rdma_send_ctxt *sctxt,
+ struct svc_rdma_recv_ctxt *rctxt,
+ int status)
+{
+ __be32 *rdma_argp = rctxt->rc_recv_buf;
+ __be32 *p;
+
+ rpcrdma_set_xdrlen(&sctxt->sc_hdrbuf, 0);
+ xdr_init_encode(&sctxt->sc_stream, &sctxt->sc_hdrbuf,
+ sctxt->sc_xprt_buf, NULL);
+
+ p = xdr_reserve_space(&sctxt->sc_stream,
+ rpcrdma_fixed_maxsz * sizeof(*p));
+ if (!p)
+ goto put_ctxt;
+
+ *p++ = *rdma_argp;
+ *p++ = *(rdma_argp + 1);
+ *p++ = rdma->sc_fc_credits;
+ *p = rdma_error;
+
+ switch (status) {
+ case -EPROTONOSUPPORT:
+ p = xdr_reserve_space(&sctxt->sc_stream, 3 * sizeof(*p));
+ if (!p)
+ goto put_ctxt;
+
+ *p++ = err_vers;
+ *p++ = rpcrdma_version;
+ *p = rpcrdma_version;
+ trace_svcrdma_err_vers(*rdma_argp);
+ break;
+ default:
+ p = xdr_reserve_space(&sctxt->sc_stream, sizeof(*p));
+ if (!p)
+ goto put_ctxt;
+
+ *p = err_chunk;
+ trace_svcrdma_err_chunk(*rdma_argp);
+ }
+
+ /* Remote Invalidation is skipped for simplicity. */
+ sctxt->sc_send_wr.num_sge = 1;
+ sctxt->sc_send_wr.opcode = IB_WR_SEND;
+ sctxt->sc_sges[0].length = sctxt->sc_hdrbuf.len;
+ if (svc_rdma_send(rdma, sctxt))
+ goto put_ctxt;
+
+ wait_for_completion_killable(&sctxt->sc_done);
+
+put_ctxt:
+ svc_rdma_send_ctxt_put(rdma, sctxt);
+}
+
+/**
+ * svc_rdma_sendto - Transmit an RPC reply
+ * @rqstp: processed RPC request, reply XDR already in ::rq_res
+ *
+ * Any resources still associated with @rqstp are released upon return.
+ * If no reply message was possible, the connection is closed.
+ *
+ * Returns:
+ * %0 if an RPC reply has been successfully posted,
+ * %-ENOMEM if a resource shortage occurred (connection is lost),
+ * %-ENOTCONN if posting failed (connection is lost).
+ */
+int svc_rdma_sendto(struct svc_rqst *rqstp)
+{
+ struct svc_xprt *xprt = rqstp->rq_xprt;
+ struct svcxprt_rdma *rdma =
+ container_of(xprt, struct svcxprt_rdma, sc_xprt);
+ struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt;
+ __be32 *rdma_argp = rctxt->rc_recv_buf;
+ struct svc_rdma_send_ctxt *sctxt;
+ unsigned int rc_size;
+ __be32 *p;
+ int ret;
+
+ ret = -ENOTCONN;
+ if (svc_xprt_is_dead(xprt))
+ goto drop_connection;
+
+ ret = -ENOMEM;
+ sctxt = svc_rdma_send_ctxt_get(rdma);
+ if (!sctxt)
+ goto drop_connection;
+
+ ret = -EMSGSIZE;
+ p = xdr_reserve_space(&sctxt->sc_stream,
+ rpcrdma_fixed_maxsz * sizeof(*p));
+ if (!p)
+ goto put_ctxt;
+
+ ret = svc_rdma_send_reply_chunk(rdma, rctxt, &rqstp->rq_res);
+ if (ret < 0)
+ goto reply_chunk;
+ rc_size = ret;
+
+ *p++ = *rdma_argp;
+ *p++ = *(rdma_argp + 1);
+ *p++ = rdma->sc_fc_credits;
+ *p = pcl_is_empty(&rctxt->rc_reply_pcl) ? rdma_msg : rdma_nomsg;
+
+ ret = svc_rdma_encode_read_list(sctxt);
+ if (ret < 0)
+ goto put_ctxt;
+ ret = svc_rdma_encode_write_list(rctxt, sctxt);
+ if (ret < 0)
+ goto put_ctxt;
+ ret = svc_rdma_encode_reply_chunk(rctxt, sctxt, rc_size);
+ if (ret < 0)
+ goto put_ctxt;
+
+ ret = svc_rdma_send_reply_msg(rdma, sctxt, rctxt, rqstp);
+ if (ret < 0)
+ goto put_ctxt;
+
+ /* Prevent svc_xprt_release() from releasing the page backing
+ * rq_res.head[0].iov_base. It's no longer being accessed by
+ * the I/O device. */
+ rqstp->rq_respages++;
+ return 0;
+
+reply_chunk:
+ if (ret != -E2BIG && ret != -EINVAL)
+ goto put_ctxt;
+
+ svc_rdma_send_error_msg(rdma, sctxt, rctxt, ret);
+ return 0;
+
+put_ctxt:
+ svc_rdma_send_ctxt_put(rdma, sctxt);
+drop_connection:
+ trace_svcrdma_send_err(rqstp, ret);
+ svc_xprt_deferred_close(&rdma->sc_xprt);
+ return -ENOTCONN;
+}
+
+/**
+ * svc_rdma_result_payload - special processing for a result payload
+ * @rqstp: svc_rqst to operate on
+ * @offset: payload's byte offset in @xdr
+ * @length: size of payload, in bytes
+ *
+ * Return values:
+ * %0 if successful or nothing needed to be done
+ * %-EMSGSIZE on XDR buffer overflow
+ * %-E2BIG if the payload was larger than the Write chunk
+ * %-EINVAL if client provided too many segments
+ * %-ENOMEM if rdma_rw context pool was exhausted
+ * %-ENOTCONN if posting failed (connection is lost)
+ * %-EIO if rdma_rw initialization failed (DMA mapping, etc)
+ */
+int svc_rdma_result_payload(struct svc_rqst *rqstp, unsigned int offset,
+ unsigned int length)
+{
+ struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt;
+ struct svc_rdma_chunk *chunk;
+ struct svcxprt_rdma *rdma;
+ struct xdr_buf subbuf;
+ int ret;
+
+ chunk = rctxt->rc_cur_result_payload;
+ if (!length || !chunk)
+ return 0;
+ rctxt->rc_cur_result_payload =
+ pcl_next_chunk(&rctxt->rc_write_pcl, chunk);
+ if (length > chunk->ch_length)
+ return -E2BIG;
+
+ chunk->ch_position = offset;
+ chunk->ch_payload_length = length;
+
+ if (xdr_buf_subsegment(&rqstp->rq_res, &subbuf, offset, length))
+ return -EMSGSIZE;
+
+ rdma = container_of(rqstp->rq_xprt, struct svcxprt_rdma, sc_xprt);
+ ret = svc_rdma_send_write_chunk(rdma, chunk, &subbuf);
+ if (ret < 0)
+ return ret;
+ return 0;
+}