blob: 7b94d971feb3b7359bef0588be0804de96c96392 [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/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 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;
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;
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:
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;
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);
trace_svcrdma_dma_unmap_page(rdma,
ctxt->sc_sges[i].addr,
ctxt->sc_sges[i].length);
}
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 =
container_of(cqe, struct svc_rdma_send_ctxt, sc_cqe);
trace_svcrdma_wc_send(wc, &ctxt->sc_cid);
atomic_inc(&rdma->sc_sq_avail);
wake_up(&rdma->sc_send_wait);
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);
}
}
/**
* 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 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;
might_sleep();
/* 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)) {
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;
}
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);
set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
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
* @src: matching Write chunk in the RPC Call header
* @sctxt: Send context for the RPC Reply
* @remaining: remaining bytes of the payload left in the Write chunk
*
* Return values:
* On success, returns length in bytes of the Reply XDR buffer
* that was consumed by the Write segment
* %-EMSGSIZE on XDR buffer overflow
*/
static ssize_t svc_rdma_encode_write_segment(__be32 *src,
struct svc_rdma_send_ctxt *sctxt,
unsigned int *remaining)
{
__be32 *p;
const size_t len = rpcrdma_segment_maxsz * sizeof(*p);
u32 handle, length;
u64 offset;
p = xdr_reserve_space(&sctxt->sc_stream, len);
if (!p)
return -EMSGSIZE;
xdr_decode_rdma_segment(src, &handle, &length, &offset);
if (*remaining < length) {
/* segment only partly filled */
length = *remaining;
*remaining = 0;
} else {
/* entire segment was consumed */
*remaining -= length;
}
xdr_encode_rdma_segment(p, handle, length, offset);
trace_svcrdma_encode_wseg(handle, length, offset);
return len;
}
/**
* svc_rdma_encode_write_chunk - Encode one Write chunk
* @src: matching Write chunk in the RPC Call header
* @sctxt: Send context for the RPC Reply
* @remaining: size in bytes of the payload in the Write chunk
*
* 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(__be32 *src,
struct svc_rdma_send_ctxt *sctxt,
unsigned int remaining)
{
unsigned int i, nsegs;
ssize_t len, ret;
len = 0;
trace_svcrdma_encode_write_chunk(remaining);
src++;
ret = xdr_stream_encode_item_present(&sctxt->sc_stream);
if (ret < 0)
return -EMSGSIZE;
len += ret;
nsegs = be32_to_cpup(src++);
ret = xdr_stream_encode_u32(&sctxt->sc_stream, nsegs);
if (ret < 0)
return -EMSGSIZE;
len += ret;
for (i = nsegs; i; i--) {
ret = svc_rdma_encode_write_segment(src, sctxt, &remaining);
if (ret < 0)
return -EMSGSIZE;
src += rpcrdma_segment_maxsz;
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
* @length: size in bytes of the payload in the first Write chunk
*
* The client provides a Write chunk 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
*
* 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(const struct svc_rdma_recv_ctxt *rctxt,
struct svc_rdma_send_ctxt *sctxt,
unsigned int length)
{
ssize_t len, ret;
ret = svc_rdma_encode_write_chunk(rctxt->rc_write_list, sctxt, length);
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
*
* Assumptions:
* - Reply can always fit in the client-provided 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
*/
static ssize_t
svc_rdma_encode_reply_chunk(const struct svc_rdma_recv_ctxt *rctxt,
struct svc_rdma_send_ctxt *sctxt,
unsigned int length)
{
return svc_rdma_encode_write_chunk(rctxt->rc_reply_chunk, sctxt,
length);
}
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);
trace_svcrdma_dma_map_page(rdma, dma_addr, len);
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:
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_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(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *sctxt,
const struct svc_rdma_recv_ctxt *rctxt,
struct xdr_buf *xdr)
{
int elements;
/* For small messages, copying bytes is cheaper than DMA mapping.
*/
if (sctxt->sc_hdrbuf.len + xdr->len < RPCRDMA_PULLUP_THRESH)
return true;
/* Check whether the xdr_buf has more elements than can
* fit in a single RDMA Send.
*/
/* xdr->head */
elements = 1;
/* xdr->pages */
if (!rctxt || !rctxt->rc_write_list) {
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;
}
/**
* 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.
*
* Returns zero on success, or a negative errno on failure.
*/
static int svc_rdma_pull_up_reply_msg(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *sctxt,
const struct svc_rdma_recv_ctxt *rctxt,
const struct xdr_buf *xdr)
{
unsigned char *dst, *tailbase;
unsigned int taillen;
dst = sctxt->sc_xprt_buf + sctxt->sc_hdrbuf.len;
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 (rctxt && rctxt->rc_write_list) {
u32 xdrpad;
xdrpad = xdr_pad_size(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);
sctxt->sc_sges[0].length += xdr->len;
trace_svcrdma_send_pullup(sctxt->sc_sges[0].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
*
* Load the xdr_buf into the ctxt's sge array, and DMA map each
* element as it is added. The Send WR's num_sge field is set.
*
* 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 *sctxt,
const struct svc_rdma_recv_ctxt *rctxt,
struct xdr_buf *xdr)
{
unsigned int len, remaining;
unsigned long page_off;
struct page **ppages;
unsigned char *base;
u32 xdr_pad;
int ret;
/* 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 (rctxt && rctxt->rc_reply_chunk)
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);
++sctxt->sc_cur_sge_no;
ret = svc_rdma_dma_map_buf(rdma, sctxt,
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 (rctxt && rctxt->rc_write_list) {
base = xdr->tail[0].iov_base;
len = xdr->tail[0].iov_len;
xdr_pad = xdr_pad_size(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);
++sctxt->sc_cur_sge_no;
ret = svc_rdma_dma_map_page(rdma, sctxt, *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) {
++sctxt->sc_cur_sge_no;
ret = svc_rdma_dma_map_buf(rdma, sctxt, 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 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;
svc_rdma_save_io_pages(rqstp, sctxt);
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;
}
return svc_rdma_send(rdma, sctxt);
}
/**
* 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;
return;
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;
__be32 *wr_lst = rctxt->rc_write_list;
__be32 *rp_ch = rctxt->rc_reply_chunk;
struct xdr_buf *xdr = &rqstp->rq_res;
struct svc_rdma_send_ctxt *sctxt;
__be32 *p;
int ret;
ret = -ENOTCONN;
if (svc_xprt_is_dead(xprt))
goto err0;
ret = -ENOMEM;
sctxt = svc_rdma_send_ctxt_get(rdma);
if (!sctxt)
goto err0;
p = xdr_reserve_space(&sctxt->sc_stream,
rpcrdma_fixed_maxsz * sizeof(*p));
if (!p)
goto err0;
*p++ = *rdma_argp;
*p++ = *(rdma_argp + 1);
*p++ = rdma->sc_fc_credits;
*p = rp_ch ? rdma_nomsg : rdma_msg;
if (svc_rdma_encode_read_list(sctxt) < 0)
goto err0;
if (wr_lst) {
/* XXX: Presume the client sent only one Write chunk */
unsigned long offset;
unsigned int length;
if (rctxt->rc_read_payload_length) {
offset = rctxt->rc_read_payload_offset;
length = rctxt->rc_read_payload_length;
} else {
offset = xdr->head[0].iov_len;
length = xdr->page_len;
}
ret = svc_rdma_send_write_chunk(rdma, wr_lst, xdr, offset,
length);
if (ret < 0)
goto err2;
if (svc_rdma_encode_write_list(rctxt, sctxt, length) < 0)
goto err0;
} else {
if (xdr_stream_encode_item_absent(&sctxt->sc_stream) < 0)
goto err0;
}
if (rp_ch) {
ret = svc_rdma_send_reply_chunk(rdma, rctxt, &rqstp->rq_res);
if (ret < 0)
goto err2;
if (svc_rdma_encode_reply_chunk(rctxt, sctxt, ret) < 0)
goto err0;
} else {
if (xdr_stream_encode_item_absent(&sctxt->sc_stream) < 0)
goto err0;
}
ret = svc_rdma_send_reply_msg(rdma, sctxt, rctxt, rqstp);
if (ret < 0)
goto err1;
return 0;
err2:
if (ret != -E2BIG && ret != -EINVAL)
goto err1;
/* Send completion releases payload pages that were part
* of previously posted RDMA Writes.
*/
svc_rdma_save_io_pages(rqstp, sctxt);
svc_rdma_send_error_msg(rdma, sctxt, rctxt, ret);
return 0;
err1:
svc_rdma_send_ctxt_put(rdma, sctxt);
err0:
trace_svcrdma_send_err(rqstp, ret);
set_bit(XPT_CLOSE, &xprt->xpt_flags);
return -ENOTCONN;
}
/**
* svc_rdma_read_payload - special processing for a READ payload
* @rqstp: svc_rqst to operate on
* @offset: payload's byte offset in @xdr
* @length: size of payload, in bytes
*
* Returns zero on success.
*
* For the moment, just record the xdr_buf location of the READ
* payload. svc_rdma_sendto will use that location later when
* we actually send the payload.
*/
int svc_rdma_read_payload(struct svc_rqst *rqstp, unsigned int offset,
unsigned int length)
{
struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt;
/* XXX: Just one READ payload slot for now, since our
* transport implementation currently supports only one
* Write chunk.
*/
rctxt->rc_read_payload_offset = offset;
rctxt->rc_read_payload_length = length;
return 0;
}