// 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 <[email protected]>
*/
/* 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 <linux/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 struct svc_rdma_send_ctxt *
svc_rdma_send_ctxt_alloc(struct svcxprt_rdma *rdma)
{
int node = ibdev_to_node(rdma->sc_cm_id->device);
struct svc_rdma_send_ctxt *ctxt;
dma_addr_t addr;
void *buffer;
int i;
ctxt = kzalloc_node(struct_size(ctxt, sc_sges, rdma->sc_max_send_sges),
GFP_KERNEL, node);
if (!ctxt)
goto fail0;
buffer = kmalloc_node(rdma->sc_max_req_size, GFP_KERNEL, node);
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_rdma = rdma;
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;
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);
spin_unlock(&rdma->sc_send_lock);
if (!node)
goto out_empty;
ctxt = llist_entry(node, struct svc_rdma_send_ctxt, sc_node);
out:
rpcrdma_set_xdrlen(&ctxt->sc_hdrbuf, 0);
xdr_init_encode(&ctxt->sc_stream, &ctxt->sc_hdrbuf,
ctxt->sc_xprt_buf, NULL);
svc_rdma_cc_init(rdma, &ctxt->sc_reply_info.wi_cc);
ctxt->sc_send_wr.num_sge = 0;
ctxt->sc_cur_sge_no = 0;
ctxt->sc_page_count = 0;
ctxt->sc_wr_chain = &ctxt->sc_send_wr;
ctxt->sc_sqecount = 1;
return ctxt;
out_empty:
ctxt = svc_rdma_send_ctxt_alloc(rdma);
if (!ctxt)
return NULL;
goto out;
}
static void svc_rdma_send_ctxt_release(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *ctxt)
{
struct ib_device *device = rdma->sc_cm_id->device;
unsigned int i;
svc_rdma_reply_chunk_release(rdma, ctxt);
if (ctxt->sc_page_count)
release_pages(ctxt->sc_pages, ctxt->sc_page_count);
/* 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++) {
trace_svcrdma_dma_unmap_page(&ctxt->sc_cid,
ctxt->sc_sges[i].addr,
ctxt->sc_sges[i].length);
ib_dma_unmap_page(device,
ctxt->sc_sges[i].addr,
ctxt->sc_sges[i].length,
DMA_TO_DEVICE);
}
llist_add(&ctxt->sc_node, &rdma->sc_send_ctxts);
}
static void svc_rdma_send_ctxt_put_async(struct work_struct *work)
{
struct svc_rdma_send_ctxt *ctxt;
ctxt = container_of(work, struct svc_rdma_send_ctxt, sc_work);
svc_rdma_send_ctxt_release(ctxt->sc_rdma, ctxt);
}
/**
* 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)
{
INIT_WORK(&ctxt->sc_work, svc_rdma_send_ctxt_put_async);
queue_work(svcrdma_wq, &ctxt->sc_work);
}
/**
* 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, ctxt->sc_sqecount);
if (unlikely(wc->status != IB_WC_SUCCESS))
goto flushed;
trace_svcrdma_wc_send(&ctxt->sc_cid);
svc_rdma_send_ctxt_put(rdma, ctxt);
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_rdma_send_ctxt_put(rdma, ctxt);
svc_xprt_deferred_close(&rdma->sc_xprt);
}
/**
* svc_rdma_post_send - Post a WR chain to the Send Queue
* @rdma: transport context
* @ctxt: WR chain to post
*
* Copy fields in @ctxt to stack variables in order to guarantee
* that these values remain available after the ib_post_send() call.
* In some error flow cases, svc_rdma_wc_send() releases @ctxt.
*
* Note there is potential for starvation when the Send Queue is
* full because there is no order to when waiting threads are
* awoken. The transport is typically provisioned with a deep
* enough Send Queue that SQ exhaustion should be a rare event.
*
* Return values:
* %0: @ctxt's WR chain was posted successfully
* %-ENOTCONN: The connection was lost
*/
int svc_rdma_post_send(struct svcxprt_rdma *rdma,
struct svc_rdma_send_ctxt *ctxt)
{
struct ib_send_wr *first_wr = ctxt->sc_wr_chain;
struct ib_send_wr *send_wr = &ctxt->sc_send_wr;
const struct ib_send_wr *bad_wr = first_wr;
struct rpc_rdma_cid cid = ctxt->sc_cid;
int ret, sqecount = ctxt->sc_sqecount;
might_sleep();
/* Sync the transport header buffer */
ib_dma_sync_single_for_device(rdma->sc_pd->device,
send_wr->sg_list[0].addr,
send_wr->sg_list[0].length,
DMA_TO_DEVICE);
/* If the SQ is full, wait until an SQ entry is available */
while (!test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags)) {
if (atomic_sub_return(sqecount, &rdma->sc_sq_avail) < 0) {
svc_rdma_wake_send_waiters(rdma, sqecount);
/* When the transport is torn down, assume
* ib_drain_sq() will trigger enough Send
* completions to wake us. The XPT_CLOSE test
* above should then cause the while loop to
* exit.
*/
percpu_counter_inc(&svcrdma_stat_sq_starve);
trace_svcrdma_sq_full(rdma, &cid);
wait_event(rdma->sc_send_wait,
atomic_read(&rdma->sc_sq_avail) > 0);
trace_svcrdma_sq_retry(rdma, &cid);
continue;
}
trace_svcrdma_post_send(ctxt);
ret = ib_post_send(rdma->sc_qp, first_wr, &bad_wr);
if (ret) {
trace_svcrdma_sq_post_err(rdma, &cid, ret);
svc_xprt_deferred_close(&rdma->sc_xprt);
/* If even one WR was posted, there will be a
* Send completion that bumps sc_sq_avail.
*/
if (bad_wr == first_wr) {
svc_rdma_wake_send_waiters(rdma, sqecount);
break;
}
}
return 0;
}
return -ENOTCONN;
}
/**
* 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(&ctxt->sc_cid, 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(&ctxt->sc_cid, 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
* @write_pcl: Write chunk list 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_pcl *write_pcl,
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(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
* @write_pcl: Write chunk list 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_pcl *write_pcl,
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(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
* @write_pcl: Write chunk list provided by client
* @reply_pcl: Reply chunk 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_pcl *write_pcl,
const struct svc_rdma_pcl *reply_pcl,
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, so there is nothing to map.
*/
if (!pcl_is_empty(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, write_pcl, xdr))
return svc_rdma_pull_up_reply_msg(rdma, sctxt, write_pcl, xdr);
return pcl_process_nonpayloads(write_pcl, xdr,
svc_rdma_xb_dma_map, &args);
}
/* 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.
*
* 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)
{
struct ib_send_wr *send_wr = &sctxt->sc_send_wr;
int ret;
ret = svc_rdma_map_reply_msg(rdma, sctxt, &rctxt->rc_write_pcl,
&rctxt->rc_reply_pcl, &rqstp->rq_res);
if (ret < 0)
return ret;
/* Transfer pages involved in RDMA Writes to the sctxt's
* page array. Completion handling releases these pages.
*/
svc_rdma_save_io_pages(rqstp, sctxt);
if (rctxt->rc_inv_rkey) {
send_wr->opcode = IB_WR_SEND_WITH_INV;
send_wr->ex.invalidate_rkey = rctxt->rc_inv_rkey;
} else {
send_wr->opcode = IB_WR_SEND;
}
return svc_rdma_post_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_post_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;
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_write_list(rdma, rctxt, &rqstp->rq_res);
if (ret < 0)
goto put_ctxt;
rc_size = 0;
if (!pcl_is_empty(&rctxt->rc_reply_pcl)) {
ret = svc_rdma_prepare_reply_chunk(rdma, &rctxt->rc_write_pcl,
&rctxt->rc_reply_pcl, sctxt,
&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;
return 0;
reply_chunk:
if (ret != -E2BIG && ret != -EINVAL)
goto put_ctxt;
/* 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;
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: RPC transaction context
* @offset: payload's byte offset in @rqstp->rq_res
* @length: size of payload, in bytes
*
* Assign the passed-in result payload to the current Write chunk,
* and advance to cur_result_payload to the next Write chunk, if
* there is one.
*
* Return values:
* %0 if successful or nothing needed to be done
* %-E2BIG if the payload was larger than the Write chunk
*/
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;
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;
return 0;
}
Codebase Browser
linux