linux/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c

882 lines
24 KiB
C

// 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_recvfrom. This is called from
* svc_recv when the transport indicates there is incoming data to
* be read. "Data Ready" is signaled when an RDMA Receive completes,
* or when a set of RDMA Reads complete.
*
* An svc_rqst is passed in. This structure contains an array of
* free pages (rq_pages) that will contain the incoming RPC message.
*
* Short messages are moved directly into svc_rqst::rq_arg, and
* the RPC Call is ready to be processed by the Upper Layer.
* svc_rdma_recvfrom returns the length of the RPC Call message,
* completing the reception of the RPC Call.
*
* However, when an incoming message has Read chunks,
* svc_rdma_recvfrom must post RDMA Reads to pull the RPC Call's
* data payload from the client. svc_rdma_recvfrom sets up the
* RDMA Reads using pages in svc_rqst::rq_pages, which are
* transferred to an svc_rdma_recv_ctxt for the duration of the
* I/O. svc_rdma_recvfrom then returns zero, since the RPC message
* is still not yet ready.
*
* When the Read chunk payloads have become available on the
* server, "Data Ready" is raised again, and svc_recv calls
* svc_rdma_recvfrom again. This second call may use a different
* svc_rqst than the first one, thus any information that needs
* to be preserved across these two calls is kept in an
* svc_rdma_recv_ctxt.
*
* The second call to svc_rdma_recvfrom performs final assembly
* of the RPC Call message, using the RDMA Read sink pages kept in
* the svc_rdma_recv_ctxt. The xdr_buf is copied from the
* svc_rdma_recv_ctxt to the second svc_rqst. The second call returns
* the length of the completed RPC Call message.
*
* Page Management
*
* Pages under I/O must be transferred from the first svc_rqst to an
* svc_rdma_recv_ctxt before the first svc_rdma_recvfrom call returns.
*
* The first svc_rqst supplies pages for RDMA Reads. These are moved
* from rqstp::rq_pages into ctxt::pages. The consumed elements of
* the rq_pages array are set to NULL and refilled with the first
* svc_rdma_recvfrom call returns.
*
* During the second svc_rdma_recvfrom call, RDMA Read sink pages
* are transferred from the svc_rdma_recv_ctxt to the second svc_rqst
* (see rdma_read_complete() below).
*/
#include <linux/spinlock.h>
#include <asm/unaligned.h>
#include <rdma/ib_verbs.h>
#include <rdma/rdma_cm.h>
#include <linux/sunrpc/xdr.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_receive(struct ib_cq *cq, struct ib_wc *wc);
static inline struct svc_rdma_recv_ctxt *
svc_rdma_next_recv_ctxt(struct list_head *list)
{
return list_first_entry_or_null(list, struct svc_rdma_recv_ctxt,
rc_list);
}
static void svc_rdma_recv_cid_init(struct svcxprt_rdma *rdma,
struct rpc_rdma_cid *cid)
{
cid->ci_queue_id = rdma->sc_rq_cq->res.id;
cid->ci_completion_id = atomic_inc_return(&rdma->sc_completion_ids);
}
static struct svc_rdma_recv_ctxt *
svc_rdma_recv_ctxt_alloc(struct svcxprt_rdma *rdma)
{
struct svc_rdma_recv_ctxt *ctxt;
dma_addr_t addr;
void *buffer;
ctxt = kmalloc(sizeof(*ctxt), 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_FROM_DEVICE);
if (ib_dma_mapping_error(rdma->sc_pd->device, addr))
goto fail2;
svc_rdma_recv_cid_init(rdma, &ctxt->rc_cid);
ctxt->rc_recv_wr.next = NULL;
ctxt->rc_recv_wr.wr_cqe = &ctxt->rc_cqe;
ctxt->rc_recv_wr.sg_list = &ctxt->rc_recv_sge;
ctxt->rc_recv_wr.num_sge = 1;
ctxt->rc_cqe.done = svc_rdma_wc_receive;
ctxt->rc_recv_sge.addr = addr;
ctxt->rc_recv_sge.length = rdma->sc_max_req_size;
ctxt->rc_recv_sge.lkey = rdma->sc_pd->local_dma_lkey;
ctxt->rc_recv_buf = buffer;
ctxt->rc_temp = false;
return ctxt;
fail2:
kfree(buffer);
fail1:
kfree(ctxt);
fail0:
return NULL;
}
static void svc_rdma_recv_ctxt_destroy(struct svcxprt_rdma *rdma,
struct svc_rdma_recv_ctxt *ctxt)
{
ib_dma_unmap_single(rdma->sc_pd->device, ctxt->rc_recv_sge.addr,
ctxt->rc_recv_sge.length, DMA_FROM_DEVICE);
kfree(ctxt->rc_recv_buf);
kfree(ctxt);
}
/**
* svc_rdma_recv_ctxts_destroy - Release all recv_ctxt's for an xprt
* @rdma: svcxprt_rdma being torn down
*
*/
void svc_rdma_recv_ctxts_destroy(struct svcxprt_rdma *rdma)
{
struct svc_rdma_recv_ctxt *ctxt;
struct llist_node *node;
while ((node = llist_del_first(&rdma->sc_recv_ctxts))) {
ctxt = llist_entry(node, struct svc_rdma_recv_ctxt, rc_node);
svc_rdma_recv_ctxt_destroy(rdma, ctxt);
}
}
static struct svc_rdma_recv_ctxt *
svc_rdma_recv_ctxt_get(struct svcxprt_rdma *rdma)
{
struct svc_rdma_recv_ctxt *ctxt;
struct llist_node *node;
node = llist_del_first(&rdma->sc_recv_ctxts);
if (!node)
goto out_empty;
ctxt = llist_entry(node, struct svc_rdma_recv_ctxt, rc_node);
out:
ctxt->rc_page_count = 0;
ctxt->rc_read_payload_length = 0;
return ctxt;
out_empty:
ctxt = svc_rdma_recv_ctxt_alloc(rdma);
if (!ctxt)
return NULL;
goto out;
}
/**
* svc_rdma_recv_ctxt_put - Return recv_ctxt to free list
* @rdma: controlling svcxprt_rdma
* @ctxt: object to return to the free list
*
*/
void svc_rdma_recv_ctxt_put(struct svcxprt_rdma *rdma,
struct svc_rdma_recv_ctxt *ctxt)
{
unsigned int i;
for (i = 0; i < ctxt->rc_page_count; i++)
put_page(ctxt->rc_pages[i]);
if (!ctxt->rc_temp)
llist_add(&ctxt->rc_node, &rdma->sc_recv_ctxts);
else
svc_rdma_recv_ctxt_destroy(rdma, ctxt);
}
/**
* svc_rdma_release_rqst - Release transport-specific per-rqst resources
* @rqstp: svc_rqst being released
*
* Ensure that the recv_ctxt is released whether or not a Reply
* was sent. For example, the client could close the connection,
* or svc_process could drop an RPC, before the Reply is sent.
*/
void svc_rdma_release_rqst(struct svc_rqst *rqstp)
{
struct svc_rdma_recv_ctxt *ctxt = rqstp->rq_xprt_ctxt;
struct svc_xprt *xprt = rqstp->rq_xprt;
struct svcxprt_rdma *rdma =
container_of(xprt, struct svcxprt_rdma, sc_xprt);
rqstp->rq_xprt_ctxt = NULL;
if (ctxt)
svc_rdma_recv_ctxt_put(rdma, ctxt);
}
static int __svc_rdma_post_recv(struct svcxprt_rdma *rdma,
struct svc_rdma_recv_ctxt *ctxt)
{
int ret;
trace_svcrdma_post_recv(ctxt);
ret = ib_post_recv(rdma->sc_qp, &ctxt->rc_recv_wr, NULL);
if (ret)
goto err_post;
return 0;
err_post:
trace_svcrdma_rq_post_err(rdma, ret);
svc_rdma_recv_ctxt_put(rdma, ctxt);
return ret;
}
static int svc_rdma_post_recv(struct svcxprt_rdma *rdma)
{
struct svc_rdma_recv_ctxt *ctxt;
if (test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags))
return 0;
ctxt = svc_rdma_recv_ctxt_get(rdma);
if (!ctxt)
return -ENOMEM;
return __svc_rdma_post_recv(rdma, ctxt);
}
/**
* svc_rdma_post_recvs - Post initial set of Recv WRs
* @rdma: fresh svcxprt_rdma
*
* Returns true if successful, otherwise false.
*/
bool svc_rdma_post_recvs(struct svcxprt_rdma *rdma)
{
struct svc_rdma_recv_ctxt *ctxt;
unsigned int i;
int ret;
for (i = 0; i < rdma->sc_max_requests; i++) {
ctxt = svc_rdma_recv_ctxt_get(rdma);
if (!ctxt)
return false;
ctxt->rc_temp = true;
ret = __svc_rdma_post_recv(rdma, ctxt);
if (ret)
return false;
}
return true;
}
/**
* svc_rdma_wc_receive - Invoked by RDMA provider for each polled Receive WC
* @cq: Completion Queue context
* @wc: Work Completion object
*
* NB: The svc_xprt/svcxprt_rdma is pinned whenever it's possible that
* the Receive completion handler could be running.
*/
static void svc_rdma_wc_receive(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_recv_ctxt *ctxt;
/* WARNING: Only wc->wr_cqe and wc->status are reliable */
ctxt = container_of(cqe, struct svc_rdma_recv_ctxt, rc_cqe);
trace_svcrdma_wc_receive(wc, &ctxt->rc_cid);
if (wc->status != IB_WC_SUCCESS)
goto flushed;
if (svc_rdma_post_recv(rdma))
goto post_err;
/* All wc fields are now known to be valid */
ctxt->rc_byte_len = wc->byte_len;
ib_dma_sync_single_for_cpu(rdma->sc_pd->device,
ctxt->rc_recv_sge.addr,
wc->byte_len, DMA_FROM_DEVICE);
spin_lock(&rdma->sc_rq_dto_lock);
list_add_tail(&ctxt->rc_list, &rdma->sc_rq_dto_q);
/* Note the unlock pairs with the smp_rmb in svc_xprt_ready: */
set_bit(XPT_DATA, &rdma->sc_xprt.xpt_flags);
spin_unlock(&rdma->sc_rq_dto_lock);
if (!test_bit(RDMAXPRT_CONN_PENDING, &rdma->sc_flags))
svc_xprt_enqueue(&rdma->sc_xprt);
return;
flushed:
post_err:
svc_rdma_recv_ctxt_put(rdma, ctxt);
set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
svc_xprt_enqueue(&rdma->sc_xprt);
}
/**
* svc_rdma_flush_recv_queues - Drain pending Receive work
* @rdma: svcxprt_rdma being shut down
*
*/
void svc_rdma_flush_recv_queues(struct svcxprt_rdma *rdma)
{
struct svc_rdma_recv_ctxt *ctxt;
while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_read_complete_q))) {
list_del(&ctxt->rc_list);
svc_rdma_recv_ctxt_put(rdma, ctxt);
}
while ((ctxt = svc_rdma_next_recv_ctxt(&rdma->sc_rq_dto_q))) {
list_del(&ctxt->rc_list);
svc_rdma_recv_ctxt_put(rdma, ctxt);
}
}
static void svc_rdma_build_arg_xdr(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *ctxt)
{
struct xdr_buf *arg = &rqstp->rq_arg;
arg->head[0].iov_base = ctxt->rc_recv_buf;
arg->head[0].iov_len = ctxt->rc_byte_len;
arg->tail[0].iov_base = NULL;
arg->tail[0].iov_len = 0;
arg->page_len = 0;
arg->page_base = 0;
arg->buflen = ctxt->rc_byte_len;
arg->len = ctxt->rc_byte_len;
}
/* This accommodates the largest possible Write chunk.
*/
#define MAX_BYTES_WRITE_CHUNK ((u32)(RPCSVC_MAXPAGES << PAGE_SHIFT))
/* This accommodates the largest possible Position-Zero
* Read chunk or Reply chunk.
*/
#define MAX_BYTES_SPECIAL_CHUNK ((u32)((RPCSVC_MAXPAGES + 2) << PAGE_SHIFT))
/* Sanity check the Read list.
*
* Implementation limits:
* - This implementation supports only one Read chunk.
*
* Sanity checks:
* - Read list does not overflow Receive buffer.
* - Segment size limited by largest NFS data payload.
*
* The segment count is limited to how many segments can
* fit in the transport header without overflowing the
* buffer. That's about 40 Read segments for a 1KB inline
* threshold.
*
* Return values:
* %true: Read list is valid. @rctxt's xdr_stream is updated
* to point to the first byte past the Read list.
* %false: Read list is corrupt. @rctxt's xdr_stream is left
* in an unknown state.
*/
static bool xdr_check_read_list(struct svc_rdma_recv_ctxt *rctxt)
{
u32 position, len;
bool first;
__be32 *p;
p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p));
if (!p)
return false;
len = 0;
first = true;
while (xdr_item_is_present(p)) {
p = xdr_inline_decode(&rctxt->rc_stream,
rpcrdma_readseg_maxsz * sizeof(*p));
if (!p)
return false;
if (first) {
position = be32_to_cpup(p);
first = false;
} else if (be32_to_cpup(p) != position) {
return false;
}
p += 2;
len += be32_to_cpup(p);
p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p));
if (!p)
return false;
}
return len <= MAX_BYTES_SPECIAL_CHUNK;
}
/* The segment count is limited to how many segments can
* fit in the transport header without overflowing the
* buffer. That's about 60 Write segments for a 1KB inline
* threshold.
*/
static bool xdr_check_write_chunk(struct svc_rdma_recv_ctxt *rctxt, u32 maxlen)
{
u32 i, segcount, total;
__be32 *p;
p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p));
if (!p)
return false;
segcount = be32_to_cpup(p);
total = 0;
for (i = 0; i < segcount; i++) {
u32 handle, length;
u64 offset;
p = xdr_inline_decode(&rctxt->rc_stream,
rpcrdma_segment_maxsz * sizeof(*p));
if (!p)
return false;
xdr_decode_rdma_segment(p, &handle, &length, &offset);
trace_svcrdma_decode_wseg(handle, length, offset);
total += length;
}
return total <= maxlen;
}
/* Sanity check the Write list.
*
* Implementation limits:
* - This implementation currently supports only one Write chunk.
*
* Sanity checks:
* - Write list does not overflow Receive buffer.
* - Chunk size limited by largest NFS data payload.
*
* Return values:
* %true: Write list is valid. @rctxt's xdr_stream is updated
* to point to the first byte past the Write list.
* %false: Write list is corrupt. @rctxt's xdr_stream is left
* in an unknown state.
*/
static bool xdr_check_write_list(struct svc_rdma_recv_ctxt *rctxt)
{
u32 chcount = 0;
__be32 *p;
p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p));
if (!p)
return false;
rctxt->rc_write_list = p;
while (xdr_item_is_present(p)) {
if (!xdr_check_write_chunk(rctxt, MAX_BYTES_WRITE_CHUNK))
return false;
++chcount;
p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p));
if (!p)
return false;
}
if (!chcount)
rctxt->rc_write_list = NULL;
return chcount < 2;
}
/* Sanity check the Reply chunk.
*
* Sanity checks:
* - Reply chunk does not overflow Receive buffer.
* - Chunk size limited by largest NFS data payload.
*
* Return values:
* %true: Reply chunk is valid. @rctxt's xdr_stream is updated
* to point to the first byte past the Reply chunk.
* %false: Reply chunk is corrupt. @rctxt's xdr_stream is left
* in an unknown state.
*/
static bool xdr_check_reply_chunk(struct svc_rdma_recv_ctxt *rctxt)
{
__be32 *p;
p = xdr_inline_decode(&rctxt->rc_stream, sizeof(*p));
if (!p)
return false;
rctxt->rc_reply_chunk = NULL;
if (xdr_item_is_present(p)) {
if (!xdr_check_write_chunk(rctxt, MAX_BYTES_SPECIAL_CHUNK))
return false;
rctxt->rc_reply_chunk = p;
}
return true;
}
/* RPC-over-RDMA Version One private extension: Remote Invalidation.
* Responder's choice: requester signals it can handle Send With
* Invalidate, and responder chooses one R_key to invalidate.
*
* If there is exactly one distinct R_key in the received transport
* header, set rc_inv_rkey to that R_key. Otherwise, set it to zero.
*
* Perform this operation while the received transport header is
* still in the CPU cache.
*/
static void svc_rdma_get_inv_rkey(struct svcxprt_rdma *rdma,
struct svc_rdma_recv_ctxt *ctxt)
{
__be32 inv_rkey, *p;
u32 i, segcount;
ctxt->rc_inv_rkey = 0;
if (!rdma->sc_snd_w_inv)
return;
inv_rkey = xdr_zero;
p = ctxt->rc_recv_buf;
p += rpcrdma_fixed_maxsz;
/* Read list */
while (xdr_item_is_present(p++)) {
p++; /* position */
if (inv_rkey == xdr_zero)
inv_rkey = *p;
else if (inv_rkey != *p)
return;
p += 4;
}
/* Write list */
while (xdr_item_is_present(p++)) {
segcount = be32_to_cpup(p++);
for (i = 0; i < segcount; i++) {
if (inv_rkey == xdr_zero)
inv_rkey = *p;
else if (inv_rkey != *p)
return;
p += 4;
}
}
/* Reply chunk */
if (xdr_item_is_present(p++)) {
segcount = be32_to_cpup(p++);
for (i = 0; i < segcount; i++) {
if (inv_rkey == xdr_zero)
inv_rkey = *p;
else if (inv_rkey != *p)
return;
p += 4;
}
}
ctxt->rc_inv_rkey = be32_to_cpu(inv_rkey);
}
/**
* svc_rdma_xdr_decode_req - Decode the transport header
* @rq_arg: xdr_buf containing ingress RPC/RDMA message
* @rctxt: state of decoding
*
* On entry, xdr->head[0].iov_base points to first byte of the
* RPC-over-RDMA transport header.
*
* On successful exit, head[0] points to first byte past the
* RPC-over-RDMA header. For RDMA_MSG, this is the RPC message.
*
* The length of the RPC-over-RDMA header is returned.
*
* Assumptions:
* - The transport header is entirely contained in the head iovec.
*/
static int svc_rdma_xdr_decode_req(struct xdr_buf *rq_arg,
struct svc_rdma_recv_ctxt *rctxt)
{
__be32 *p, *rdma_argp;
unsigned int hdr_len;
rdma_argp = rq_arg->head[0].iov_base;
xdr_init_decode(&rctxt->rc_stream, rq_arg, rdma_argp, NULL);
p = xdr_inline_decode(&rctxt->rc_stream,
rpcrdma_fixed_maxsz * sizeof(*p));
if (unlikely(!p))
goto out_short;
p++;
if (*p != rpcrdma_version)
goto out_version;
p += 2;
switch (*p) {
case rdma_msg:
break;
case rdma_nomsg:
break;
case rdma_done:
goto out_drop;
case rdma_error:
goto out_drop;
default:
goto out_proc;
}
if (!xdr_check_read_list(rctxt))
goto out_inval;
if (!xdr_check_write_list(rctxt))
goto out_inval;
if (!xdr_check_reply_chunk(rctxt))
goto out_inval;
rq_arg->head[0].iov_base = rctxt->rc_stream.p;
hdr_len = xdr_stream_pos(&rctxt->rc_stream);
rq_arg->head[0].iov_len -= hdr_len;
rq_arg->len -= hdr_len;
trace_svcrdma_decode_rqst(rctxt, rdma_argp, hdr_len);
return hdr_len;
out_short:
trace_svcrdma_decode_short_err(rctxt, rq_arg->len);
return -EINVAL;
out_version:
trace_svcrdma_decode_badvers_err(rctxt, rdma_argp);
return -EPROTONOSUPPORT;
out_drop:
trace_svcrdma_decode_drop_err(rctxt, rdma_argp);
return 0;
out_proc:
trace_svcrdma_decode_badproc_err(rctxt, rdma_argp);
return -EINVAL;
out_inval:
trace_svcrdma_decode_parse_err(rctxt, rdma_argp);
return -EINVAL;
}
static void rdma_read_complete(struct svc_rqst *rqstp,
struct svc_rdma_recv_ctxt *head)
{
int page_no;
/* Move Read chunk pages to rqstp so that they will be released
* when svc_process is done with them.
*/
for (page_no = 0; page_no < head->rc_page_count; page_no++) {
put_page(rqstp->rq_pages[page_no]);
rqstp->rq_pages[page_no] = head->rc_pages[page_no];
}
head->rc_page_count = 0;
/* Point rq_arg.pages past header */
rqstp->rq_arg.pages = &rqstp->rq_pages[head->rc_hdr_count];
rqstp->rq_arg.page_len = head->rc_arg.page_len;
/* rq_respages starts after the last arg page */
rqstp->rq_respages = &rqstp->rq_pages[page_no];
rqstp->rq_next_page = rqstp->rq_respages + 1;
/* Rebuild rq_arg head and tail. */
rqstp->rq_arg.head[0] = head->rc_arg.head[0];
rqstp->rq_arg.tail[0] = head->rc_arg.tail[0];
rqstp->rq_arg.len = head->rc_arg.len;
rqstp->rq_arg.buflen = head->rc_arg.buflen;
}
static void svc_rdma_send_error(struct svcxprt_rdma *rdma,
struct svc_rdma_recv_ctxt *rctxt,
int status)
{
struct svc_rdma_send_ctxt *sctxt;
sctxt = svc_rdma_send_ctxt_get(rdma);
if (!sctxt)
return;
svc_rdma_send_error_msg(rdma, sctxt, rctxt, status);
}
/* By convention, backchannel calls arrive via rdma_msg type
* messages, and never populate the chunk lists. This makes
* the RPC/RDMA header small and fixed in size, so it is
* straightforward to check the RPC header's direction field.
*/
static bool svc_rdma_is_backchannel_reply(struct svc_xprt *xprt,
__be32 *rdma_resp)
{
__be32 *p;
if (!xprt->xpt_bc_xprt)
return false;
p = rdma_resp + 3;
if (*p++ != rdma_msg)
return false;
if (*p++ != xdr_zero)
return false;
if (*p++ != xdr_zero)
return false;
if (*p++ != xdr_zero)
return false;
/* XID sanity */
if (*p++ != *rdma_resp)
return false;
/* call direction */
if (*p == cpu_to_be32(RPC_CALL))
return false;
return true;
}
/**
* svc_rdma_recvfrom - Receive an RPC call
* @rqstp: request structure into which to receive an RPC Call
*
* Returns:
* The positive number of bytes in the RPC Call message,
* %0 if there were no Calls ready to return,
* %-EINVAL if the Read chunk data is too large,
* %-ENOMEM if rdma_rw context pool was exhausted,
* %-ENOTCONN if posting failed (connection is lost),
* %-EIO if rdma_rw initialization failed (DMA mapping, etc).
*
* Called in a loop when XPT_DATA is set. XPT_DATA is cleared only
* when there are no remaining ctxt's to process.
*
* The next ctxt is removed from the "receive" lists.
*
* - If the ctxt completes a Read, then finish assembling the Call
* message and return the number of bytes in the message.
*
* - If the ctxt completes a Receive, then construct the Call
* message from the contents of the Receive buffer.
*
* - If there are no Read chunks in this message, then finish
* assembling the Call message and return the number of bytes
* in the message.
*
* - If there are Read chunks in this message, post Read WRs to
* pull that payload and return 0.
*/
int svc_rdma_recvfrom(struct svc_rqst *rqstp)
{
struct svc_xprt *xprt = rqstp->rq_xprt;
struct svcxprt_rdma *rdma_xprt =
container_of(xprt, struct svcxprt_rdma, sc_xprt);
struct svc_rdma_recv_ctxt *ctxt;
__be32 *p;
int ret;
rqstp->rq_xprt_ctxt = NULL;
spin_lock(&rdma_xprt->sc_rq_dto_lock);
ctxt = svc_rdma_next_recv_ctxt(&rdma_xprt->sc_read_complete_q);
if (ctxt) {
list_del(&ctxt->rc_list);
spin_unlock(&rdma_xprt->sc_rq_dto_lock);
rdma_read_complete(rqstp, ctxt);
goto complete;
}
ctxt = svc_rdma_next_recv_ctxt(&rdma_xprt->sc_rq_dto_q);
if (!ctxt) {
/* No new incoming requests, terminate the loop */
clear_bit(XPT_DATA, &xprt->xpt_flags);
spin_unlock(&rdma_xprt->sc_rq_dto_lock);
return 0;
}
list_del(&ctxt->rc_list);
spin_unlock(&rdma_xprt->sc_rq_dto_lock);
atomic_inc(&rdma_stat_recv);
svc_rdma_build_arg_xdr(rqstp, ctxt);
/* Prevent svc_xprt_release from releasing pages in rq_pages
* if we return 0 or an error.
*/
rqstp->rq_respages = rqstp->rq_pages;
rqstp->rq_next_page = rqstp->rq_respages;
p = (__be32 *)rqstp->rq_arg.head[0].iov_base;
ret = svc_rdma_xdr_decode_req(&rqstp->rq_arg, ctxt);
if (ret < 0)
goto out_err;
if (ret == 0)
goto out_drop;
rqstp->rq_xprt_hlen = ret;
if (svc_rdma_is_backchannel_reply(xprt, p))
goto out_backchannel;
svc_rdma_get_inv_rkey(rdma_xprt, ctxt);
p += rpcrdma_fixed_maxsz;
if (*p != xdr_zero)
goto out_readchunk;
complete:
rqstp->rq_xprt_ctxt = ctxt;
rqstp->rq_prot = IPPROTO_MAX;
svc_xprt_copy_addrs(rqstp, xprt);
return rqstp->rq_arg.len;
out_readchunk:
ret = svc_rdma_recv_read_chunk(rdma_xprt, rqstp, ctxt, p);
if (ret < 0)
goto out_postfail;
return 0;
out_err:
svc_rdma_send_error(rdma_xprt, ctxt, ret);
svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
return 0;
out_postfail:
if (ret == -EINVAL)
svc_rdma_send_error(rdma_xprt, ctxt, ret);
svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
return ret;
out_backchannel:
svc_rdma_handle_bc_reply(rqstp, ctxt);
out_drop:
svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
return 0;
}