blob: e8ad7ddf347ad2e3af86d7e06358e9ac85137023 [file] [log] [blame]
// 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/rpc_rdma.h>
#include <linux/sunrpc/svc_rdma.h>
#include "xprt_rdma.h"
#include <trace/events/rpcrdma.h>
#define RPCDBG_FACILITY RPCDBG_SVCXPRT
static void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc);
static inline struct svc_rdma_send_ctxt *
svc_rdma_next_send_ctxt(struct list_head *list)
{
return list_first_entry_or_null(list, struct svc_rdma_send_ctxt,
sc_list);
}
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;
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;
ctxt->sc_cqe.done = svc_rdma_wc_send;
ctxt->sc_xprt_buf = buffer;
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;
while ((ctxt = svc_rdma_next_send_ctxt(&rdma->sc_send_ctxts))) {
list_del(&ctxt->sc_list);
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;
spin_lock(&rdma->sc_send_lock);
ctxt = svc_rdma_next_send_ctxt(&rdma->sc_send_ctxts);
if (!ctxt)
goto out_empty;
list_del(&ctxt->sc_list);
spin_unlock(&rdma->sc_send_lock);
out:
ctxt->sc_send_wr.num_sge = 0;
ctxt->sc_cur_sge_no = 0;
ctxt->sc_page_count = 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
*
* Pages left in sc_pages are DMA unmapped and released.
*/
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);
for (i = 0; i < ctxt->sc_page_count; ++i)
put_page(ctxt->sc_pages[i]);
spin_lock(&rdma->sc_send_lock);
list_add(&ctxt->sc_list, &rdma->sc_send_ctxts);
spin_unlock(&rdma->sc_send_lock);
}
/**
* 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;
trace_svcrdma_wc_send(wc);
atomic_inc(&rdma->sc_sq_avail);
wake_up(&rdma->sc_send_wait);
ctxt = container_of(cqe, struct svc_rdma_send_ctxt, sc_cqe);
svc_rdma_send_ctxt_put(rdma, ctxt);
if (unlikely(wc->status != IB_WC_SUCCESS)) {
set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
svc_xprt_enqueue(&rdma->sc_xprt);
if (wc->status != IB_WC_WR_FLUSH_ERR)
pr_err("svcrdma: Send: %s (%u/0x%x)\n",
ib_wc_status_msg(wc->status),
wc->status, wc->vendor_err);
}
svc_xprt_put(&rdma->sc_xprt);
}
/**
* svc_rdma_send - Post a single Send WR
* @rdma: transport on which to post the WR
* @wr: prepared Send WR to post
*
* Returns zero the Send WR was posted successfully. Otherwise, a
* negative errno is returned.
*/
int svc_rdma_send(struct svcxprt_rdma *rdma, struct ib_send_wr *wr)
{
int ret;
might_sleep();
/* If the SQ is full, wait until an SQ entry is available */
while (1) {
if ((atomic_dec_return(&rdma->sc_sq_avail) < 0)) {
atomic_inc(&rdma_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;
}
svc_xprt_get(&rdma->sc_xprt);
ret = ib_post_send(rdma->sc_qp, wr, NULL);
trace_svcrdma_post_send(wr, ret);
if (ret) {
set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
svc_xprt_put(&rdma->sc_xprt);
wake_up(&rdma->sc_send_wait);
}
break;
}
return ret;
}
static u32 xdr_padsize(u32 len)
{
return (len & 3) ? (4 - (len & 3)) : 0;
}
/* Returns length of transport header, in bytes.
*/
static unsigned int svc_rdma_reply_hdr_len(__be32 *rdma_resp)
{
unsigned int nsegs;
__be32 *p;
p = rdma_resp;
/* RPC-over-RDMA V1 replies never have a Read list. */
p += rpcrdma_fixed_maxsz + 1;
/* Skip Write list. */
while (*p++ != xdr_zero) {
nsegs = be32_to_cpup(p++);
p += nsegs * rpcrdma_segment_maxsz;
}
/* Skip Reply chunk. */
if (*p++ != xdr_zero) {
nsegs = be32_to_cpup(p++);
p += nsegs * rpcrdma_segment_maxsz;
}
return (unsigned long)p - (unsigned long)rdma_resp;
}
/* One Write chunk is copied from Call transport header to Reply
* transport header. Each segment's length field is updated to
* reflect number of bytes consumed in the segment.
*
* Returns number of segments in this chunk.
*/
static unsigned int xdr_encode_write_chunk(__be32 *dst, __be32 *src,
unsigned int remaining)
{
unsigned int i, nsegs;
u32 seg_len;
/* Write list discriminator */
*dst++ = *src++;
/* number of segments in this chunk */
nsegs = be32_to_cpup(src);
*dst++ = *src++;
for (i = nsegs; i; i--) {
/* segment's RDMA handle */
*dst++ = *src++;
/* bytes returned in this segment */
seg_len = be32_to_cpu(*src);
if (remaining >= seg_len) {
/* entire segment was consumed */
*dst = *src;
remaining -= seg_len;
} else {
/* segment only partly filled */
*dst = cpu_to_be32(remaining);
remaining = 0;
}
dst++; src++;
/* segment's RDMA offset */
*dst++ = *src++;
*dst++ = *src++;
}
return nsegs;
}
/* The client provided a Write list in the Call message. Fill in
* the segments in the first Write chunk in the Reply's transport
* header with the number of bytes consumed in each segment.
* Remaining chunks are returned unused.
*
* Assumptions:
* - Client has provided only one Write chunk
*/
static void svc_rdma_xdr_encode_write_list(__be32 *rdma_resp, __be32 *wr_ch,
unsigned int consumed)
{
unsigned int nsegs;
__be32 *p, *q;
/* RPC-over-RDMA V1 replies never have a Read list. */
p = rdma_resp + rpcrdma_fixed_maxsz + 1;
q = wr_ch;
while (*q != xdr_zero) {
nsegs = xdr_encode_write_chunk(p, q, consumed);
q += 2 + nsegs * rpcrdma_segment_maxsz;
p += 2 + nsegs * rpcrdma_segment_maxsz;
consumed = 0;
}
/* Terminate Write list */
*p++ = xdr_zero;
/* Reply chunk discriminator; may be replaced later */
*p = xdr_zero;
}
/* The client provided a Reply chunk in the Call message. Fill in
* the segments in the Reply chunk in the Reply message with the
* number of bytes consumed in each segment.
*
* Assumptions:
* - Reply can always fit in the provided Reply chunk
*/
static void svc_rdma_xdr_encode_reply_chunk(__be32 *rdma_resp, __be32 *rp_ch,
unsigned int consumed)
{
__be32 *p;
/* Find the Reply chunk in the Reply's xprt header.
* RPC-over-RDMA V1 replies never have a Read list.
*/
p = rdma_resp + rpcrdma_fixed_maxsz + 1;
/* Skip past Write list */
while (*p++ != xdr_zero)
p += 1 + be32_to_cpup(p) * rpcrdma_segment_maxsz;
xdr_encode_write_chunk(p, rp_ch, consumed);
}
/* Parse the RPC Call's transport header.
*/
static void svc_rdma_get_write_arrays(__be32 *rdma_argp,
__be32 **write, __be32 **reply)
{
__be32 *p;
p = rdma_argp + rpcrdma_fixed_maxsz;
/* Read list */
while (*p++ != xdr_zero)
p += 5;
/* Write list */
if (*p != xdr_zero) {
*write = p;
while (*p++ != xdr_zero)
p += 1 + be32_to_cpu(*p) * 4;
} else {
*write = NULL;
p++;
}
/* Reply chunk */
if (*p != xdr_zero)
*reply = p;
else
*reply = NULL;
}
/* RPC-over-RDMA Version One private extension: Remote Invalidation.
* Responder's choice: requester signals it can handle Send With
* Invalidate, and responder chooses one rkey to invalidate.
*
* Find a candidate rkey to invalidate when sending a reply. Picks the
* first R_key it finds in the chunk lists.
*
* Returns zero if RPC's chunk lists are empty.
*/
static u32 svc_rdma_get_inv_rkey(__be32 *rdma_argp,
__be32 *wr_lst, __be32 *rp_ch)
{
__be32 *p;
p = rdma_argp + rpcrdma_fixed_maxsz;
if (*p != xdr_zero)
p += 2;
else if (wr_lst && be32_to_cpup(wr_lst + 1))
p = wr_lst + 2;
else if (rp_ch && be32_to_cpup(rp_ch + 1))
p = rp_ch + 2;
else
return 0;
return be32_to_cpup(p);
}
static int svc_rdma_dma_map_page(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *ctxt,
struct page *page,
unsigned long offset,
unsigned int len)
{
struct ib_device *dev = rdma->sc_cm_id->device;
dma_addr_t dma_addr;
dma_addr = ib_dma_map_page(dev, page, offset, len, DMA_TO_DEVICE);
if (ib_dma_mapping_error(dev, dma_addr))
goto out_maperr;
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_page(rdma, page);
return -EIO;
}
/* ib_dma_map_page() is used here because svc_rdma_dma_unmap()
* handles DMA-unmap and it uses ib_dma_unmap_page() exclusively.
*/
static int svc_rdma_dma_map_buf(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *ctxt,
unsigned char *base,
unsigned int len)
{
return svc_rdma_dma_map_page(rdma, ctxt, virt_to_page(base),
offset_in_page(base), len);
}
/**
* svc_rdma_sync_reply_hdr - DMA sync the transport header buffer
* @rdma: controlling transport
* @ctxt: send_ctxt for the Send WR
* @len: length of transport header
*
*/
void svc_rdma_sync_reply_hdr(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *ctxt,
unsigned int len)
{
ctxt->sc_sges[0].length = len;
ctxt->sc_send_wr.num_sge++;
ib_dma_sync_single_for_device(rdma->sc_pd->device,
ctxt->sc_sges[0].addr, len,
DMA_TO_DEVICE);
}
/* If the xdr_buf has more elements than the device can
* transmit in a single RDMA Send, then the reply will
* have to be copied into a bounce buffer.
*/
static bool svc_rdma_pull_up_needed(struct svcxprt_rdma *rdma,
struct xdr_buf *xdr,
__be32 *wr_lst)
{
int elements;
/* xdr->head */
elements = 1;
/* xdr->pages */
if (!wr_lst) {
unsigned int remaining;
unsigned long pageoff;
pageoff = xdr->page_base & ~PAGE_MASK;
remaining = xdr->page_len;
while (remaining) {
++elements;
remaining -= min_t(u32, PAGE_SIZE - pageoff,
remaining);
pageoff = 0;
}
}
/* xdr->tail */
if (xdr->tail[0].iov_len)
++elements;
/* assume 1 SGE is needed for the transport header */
return elements >= rdma->sc_max_send_sges;
}
/* The device is not capable of sending the reply directly.
* Assemble the elements of @xdr into the transport header
* buffer.
*/
static int svc_rdma_pull_up_reply_msg(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *ctxt,
struct xdr_buf *xdr, __be32 *wr_lst)
{
unsigned char *dst, *tailbase;
unsigned int taillen;
dst = ctxt->sc_xprt_buf;
dst += ctxt->sc_sges[0].length;
memcpy(dst, xdr->head[0].iov_base, xdr->head[0].iov_len);
dst += xdr->head[0].iov_len;
tailbase = xdr->tail[0].iov_base;
taillen = xdr->tail[0].iov_len;
if (wr_lst) {
u32 xdrpad;
xdrpad = xdr_padsize(xdr->page_len);
if (taillen && xdrpad) {
tailbase += xdrpad;
taillen -= xdrpad;
}
} else {
unsigned int len, remaining;
unsigned long pageoff;
struct page **ppages;
ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
pageoff = xdr->page_base & ~PAGE_MASK;
remaining = xdr->page_len;
while (remaining) {
len = min_t(u32, PAGE_SIZE - pageoff, remaining);
memcpy(dst, page_address(*ppages), len);
remaining -= len;
dst += len;
pageoff = 0;
}
}
if (taillen)
memcpy(dst, tailbase, taillen);
ctxt->sc_sges[0].length += xdr->len;
ib_dma_sync_single_for_device(rdma->sc_pd->device,
ctxt->sc_sges[0].addr,
ctxt->sc_sges[0].length,
DMA_TO_DEVICE);
return 0;
}
/* svc_rdma_map_reply_msg - Map the buffer holding RPC message
* @rdma: controlling transport
* @ctxt: send_ctxt for the Send WR
* @xdr: prepared xdr_buf containing RPC message
* @wr_lst: pointer to Call header's Write list, or NULL
*
* Load the xdr_buf into the ctxt's sge array, and DMA map each
* element as it is added.
*
* Returns zero on success, or a negative errno on failure.
*/
int svc_rdma_map_reply_msg(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *ctxt,
struct xdr_buf *xdr, __be32 *wr_lst)
{
unsigned int len, remaining;
unsigned long page_off;
struct page **ppages;
unsigned char *base;
u32 xdr_pad;
int ret;
if (svc_rdma_pull_up_needed(rdma, xdr, wr_lst))
return svc_rdma_pull_up_reply_msg(rdma, ctxt, xdr, wr_lst);
++ctxt->sc_cur_sge_no;
ret = svc_rdma_dma_map_buf(rdma, ctxt,
xdr->head[0].iov_base,
xdr->head[0].iov_len);
if (ret < 0)
return ret;
/* If a Write chunk is present, the xdr_buf's page list
* is not included inline. However the Upper Layer may
* have added XDR padding in the tail buffer, and that
* should not be included inline.
*/
if (wr_lst) {
base = xdr->tail[0].iov_base;
len = xdr->tail[0].iov_len;
xdr_pad = xdr_padsize(xdr->page_len);
if (len && xdr_pad) {
base += xdr_pad;
len -= xdr_pad;
}
goto tail;
}
ppages = xdr->pages + (xdr->page_base >> PAGE_SHIFT);
page_off = xdr->page_base & ~PAGE_MASK;
remaining = xdr->page_len;
while (remaining) {
len = min_t(u32, PAGE_SIZE - page_off, remaining);
++ctxt->sc_cur_sge_no;
ret = svc_rdma_dma_map_page(rdma, ctxt, *ppages++,
page_off, len);
if (ret < 0)
return ret;
remaining -= len;
page_off = 0;
}
base = xdr->tail[0].iov_base;
len = xdr->tail[0].iov_len;
tail:
if (len) {
++ctxt->sc_cur_sge_no;
ret = svc_rdma_dma_map_buf(rdma, ctxt, base, len);
if (ret < 0)
return ret;
}
return 0;
}
/* The svc_rqst and all resources it owns are released as soon as
* svc_rdma_sendto returns. Transfer pages under I/O to the ctxt
* so they are released by the Send completion handler.
*/
static void svc_rdma_save_io_pages(struct svc_rqst *rqstp,
struct svc_rdma_send_ctxt *ctxt)
{
int i, pages = rqstp->rq_next_page - rqstp->rq_respages;
ctxt->sc_page_count += pages;
for (i = 0; i < pages; i++) {
ctxt->sc_pages[i] = rqstp->rq_respages[i];
rqstp->rq_respages[i] = NULL;
}
/* Prevent svc_xprt_release from releasing pages in rq_pages */
rqstp->rq_next_page = rqstp->rq_respages;
}
/* 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 ctxt'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 *ctxt,
__be32 *rdma_argp,
struct svc_rqst *rqstp,
__be32 *wr_lst, __be32 *rp_ch)
{
int ret;
if (!rp_ch) {
ret = svc_rdma_map_reply_msg(rdma, ctxt,
&rqstp->rq_res, wr_lst);
if (ret < 0)
return ret;
}
svc_rdma_save_io_pages(rqstp, ctxt);
ctxt->sc_send_wr.opcode = IB_WR_SEND;
if (rdma->sc_snd_w_inv) {
ctxt->sc_send_wr.ex.invalidate_rkey =
svc_rdma_get_inv_rkey(rdma_argp, wr_lst, rp_ch);
if (ctxt->sc_send_wr.ex.invalidate_rkey)
ctxt->sc_send_wr.opcode = IB_WR_SEND_WITH_INV;
}
dprintk("svcrdma: posting Send WR with %u sge(s)\n",
ctxt->sc_send_wr.num_sge);
return svc_rdma_send(rdma, &ctxt->sc_send_wr);
}
/* Given the client-provided Write and Reply chunks, the server was not
* able to form a complete reply. Return an RDMA_ERROR message so the
* client can retire this RPC transaction. As above, the Send completion
* routine releases payload pages that were part of a previous RDMA Write.
*
* Remote Invalidation is skipped for simplicity.
*/
static int svc_rdma_send_error_msg(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *ctxt,
struct svc_rqst *rqstp)
{
__be32 *p;
int ret;
p = ctxt->sc_xprt_buf;
trace_svcrdma_err_chunk(*p);
p += 3;
*p++ = rdma_error;
*p = err_chunk;
svc_rdma_sync_reply_hdr(rdma, ctxt, RPCRDMA_HDRLEN_ERR);
svc_rdma_save_io_pages(rqstp, ctxt);
ctxt->sc_send_wr.opcode = IB_WR_SEND;
ret = svc_rdma_send(rdma, &ctxt->sc_send_wr);
if (ret) {
svc_rdma_send_ctxt_put(rdma, ctxt);
return ret;
}
return 0;
}
void svc_rdma_prep_reply_hdr(struct svc_rqst *rqstp)
{
}
/**
* 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 *p, *rdma_argp, *rdma_resp, *wr_lst, *rp_ch;
struct xdr_buf *xdr = &rqstp->rq_res;
struct svc_rdma_send_ctxt *sctxt;
int ret;
rdma_argp = rctxt->rc_recv_buf;
svc_rdma_get_write_arrays(rdma_argp, &wr_lst, &rp_ch);
/* Create the RDMA response header. xprt->xpt_mutex,
* acquired in svc_send(), serializes RPC replies. The
* code path below that inserts the credit grant value
* into each transport header runs only inside this
* critical section.
*/
ret = -ENOMEM;
sctxt = svc_rdma_send_ctxt_get(rdma);
if (!sctxt)
goto err0;
rdma_resp = sctxt->sc_xprt_buf;
p = rdma_resp;
*p++ = *rdma_argp;
*p++ = *(rdma_argp + 1);
*p++ = rdma->sc_fc_credits;
*p++ = rp_ch ? rdma_nomsg : rdma_msg;
/* Start with empty chunks */
*p++ = xdr_zero;
*p++ = xdr_zero;
*p = xdr_zero;
if (wr_lst) {
/* XXX: Presume the client sent only one Write chunk */
ret = svc_rdma_send_write_chunk(rdma, wr_lst, xdr);
if (ret < 0)
goto err2;
svc_rdma_xdr_encode_write_list(rdma_resp, wr_lst, ret);
}
if (rp_ch) {
ret = svc_rdma_send_reply_chunk(rdma, rp_ch, wr_lst, xdr);
if (ret < 0)
goto err2;
svc_rdma_xdr_encode_reply_chunk(rdma_resp, rp_ch, ret);
}
svc_rdma_sync_reply_hdr(rdma, sctxt, svc_rdma_reply_hdr_len(rdma_resp));
ret = svc_rdma_send_reply_msg(rdma, sctxt, rdma_argp, rqstp,
wr_lst, rp_ch);
if (ret < 0)
goto err1;
ret = 0;
out:
rqstp->rq_xprt_ctxt = NULL;
svc_rdma_recv_ctxt_put(rdma, rctxt);
return ret;
err2:
if (ret != -E2BIG && ret != -EINVAL)
goto err1;
ret = svc_rdma_send_error_msg(rdma, sctxt, rqstp);
if (ret < 0)
goto err1;
ret = 0;
goto out;
err1:
svc_rdma_send_ctxt_put(rdma, sctxt);
err0:
trace_svcrdma_send_failed(rqstp, ret);
set_bit(XPT_CLOSE, &xprt->xpt_flags);
ret = -ENOTCONN;
goto out;
}