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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2015 Oracle. All rights reserved.
*
* Support for backward direction RPCs on RPC/RDMA.
*/
#include <linux/module.h>
#include <linux/sunrpc/xprt.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/svc_xprt.h>
#include "xprt_rdma.h"
#include <trace/events/rpcrdma.h>
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY RPCDBG_TRANS
#endif
#undef RPCRDMA_BACKCHANNEL_DEBUG
static void rpcrdma_bc_free_rqst(struct rpcrdma_xprt *r_xprt,
struct rpc_rqst *rqst)
{
struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
spin_lock(&buf->rb_reqslock);
list_del(&req->rl_all);
spin_unlock(&buf->rb_reqslock);
rpcrdma_destroy_req(req);
kfree(rqst);
}
static int rpcrdma_bc_setup_rqst(struct rpcrdma_xprt *r_xprt,
struct rpc_rqst *rqst)
{
struct rpcrdma_regbuf *rb;
struct rpcrdma_req *req;
size_t size;
req = rpcrdma_create_req(r_xprt);
if (IS_ERR(req))
return PTR_ERR(req);
size = r_xprt->rx_data.inline_rsize;
rb = rpcrdma_alloc_regbuf(size, DMA_TO_DEVICE, GFP_KERNEL);
if (IS_ERR(rb))
goto out_fail;
req->rl_sendbuf = rb;
xdr_buf_init(&rqst->rq_snd_buf, rb->rg_base,
min_t(size_t, size, PAGE_SIZE));
rpcrdma_set_xprtdata(rqst, req);
return 0;
out_fail:
rpcrdma_bc_free_rqst(r_xprt, rqst);
return -ENOMEM;
}
/* Allocate and add receive buffers to the rpcrdma_buffer's
* existing list of rep's. These are released when the
* transport is destroyed.
*/
static int rpcrdma_bc_setup_reps(struct rpcrdma_xprt *r_xprt,
unsigned int count)
{
int rc = 0;
while (count--) {
rc = rpcrdma_create_rep(r_xprt);
if (rc)
break;
}
return rc;
}
/**
* xprt_rdma_bc_setup - Pre-allocate resources for handling backchannel requests
* @xprt: transport associated with these backchannel resources
* @reqs: number of concurrent incoming requests to expect
*
* Returns 0 on success; otherwise a negative errno
*/
int xprt_rdma_bc_setup(struct rpc_xprt *xprt, unsigned int reqs)
{
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
struct rpcrdma_buffer *buffer = &r_xprt->rx_buf;
struct rpc_rqst *rqst;
unsigned int i;
int rc;
/* The backchannel reply path returns each rpc_rqst to the
* bc_pa_list _after_ the reply is sent. If the server is
* faster than the client, it can send another backward
* direction request before the rpc_rqst is returned to the
* list. The client rejects the request in this case.
*
* Twice as many rpc_rqsts are prepared to ensure there is
* always an rpc_rqst available as soon as a reply is sent.
*/
if (reqs > RPCRDMA_BACKWARD_WRS >> 1)
goto out_err;
for (i = 0; i < (reqs << 1); i++) {
rqst = kzalloc(sizeof(*rqst), GFP_KERNEL);
if (!rqst)
goto out_free;
dprintk("RPC: %s: new rqst %p\n", __func__, rqst);
rqst->rq_xprt = &r_xprt->rx_xprt;
INIT_LIST_HEAD(&rqst->rq_list);
INIT_LIST_HEAD(&rqst->rq_bc_list);
__set_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state);
if (rpcrdma_bc_setup_rqst(r_xprt, rqst))
goto out_free;
spin_lock_bh(&xprt->bc_pa_lock);
list_add(&rqst->rq_bc_pa_list, &xprt->bc_pa_list);
spin_unlock_bh(&xprt->bc_pa_lock);
}
rc = rpcrdma_bc_setup_reps(r_xprt, reqs);
if (rc)
goto out_free;
rc = rpcrdma_ep_post_extra_recv(r_xprt, reqs);
if (rc)
goto out_free;
buffer->rb_bc_srv_max_requests = reqs;
request_module("svcrdma");
trace_xprtrdma_cb_setup(r_xprt, reqs);
return 0;
out_free:
xprt_rdma_bc_destroy(xprt, reqs);
out_err:
pr_err("RPC: %s: setup backchannel transport failed\n", __func__);
return -ENOMEM;
}
/**
* xprt_rdma_bc_up - Create transport endpoint for backchannel service
* @serv: server endpoint
* @net: network namespace
*
* The "xprt" is an implied argument: it supplies the name of the
* backchannel transport class.
*
* Returns zero on success, negative errno on failure
*/
int xprt_rdma_bc_up(struct svc_serv *serv, struct net *net)
{
int ret;
ret = svc_create_xprt(serv, "rdma-bc", net, PF_INET, 0, 0);
if (ret < 0)
return ret;
return 0;
}
/**
* xprt_rdma_bc_maxpayload - Return maximum backchannel message size
* @xprt: transport
*
* Returns maximum size, in bytes, of a backchannel message
*/
size_t xprt_rdma_bc_maxpayload(struct rpc_xprt *xprt)
{
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
size_t maxmsg;
maxmsg = min_t(unsigned int, cdata->inline_rsize, cdata->inline_wsize);
maxmsg = min_t(unsigned int, maxmsg, PAGE_SIZE);
return maxmsg - RPCRDMA_HDRLEN_MIN;
}
static int rpcrdma_bc_marshal_reply(struct rpc_rqst *rqst)
{
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_xprt);
struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
__be32 *p;
rpcrdma_set_xdrlen(&req->rl_hdrbuf, 0);
xdr_init_encode(&req->rl_stream, &req->rl_hdrbuf,
req->rl_rdmabuf->rg_base);
p = xdr_reserve_space(&req->rl_stream, 28);
if (unlikely(!p))
return -EIO;
*p++ = rqst->rq_xid;
*p++ = rpcrdma_version;
*p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_srv_max_requests);
*p++ = rdma_msg;
*p++ = xdr_zero;
*p++ = xdr_zero;
*p = xdr_zero;
if (rpcrdma_prepare_send_sges(r_xprt, req, RPCRDMA_HDRLEN_MIN,
&rqst->rq_snd_buf, rpcrdma_noch))
return -EIO;
trace_xprtrdma_cb_reply(rqst);
return 0;
}
/**
* xprt_rdma_bc_send_reply - marshal and send a backchannel reply
* @rqst: RPC rqst with a backchannel RPC reply in rq_snd_buf
*
* Caller holds the transport's write lock.
*
* Returns:
* %0 if the RPC message has been sent
* %-ENOTCONN if the caller should reconnect and call again
* %-EIO if a permanent error occurred and the request was not
* sent. Do not try to send this message again.
*/
int xprt_rdma_bc_send_reply(struct rpc_rqst *rqst)
{
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_xprt);
struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
int rc;
if (!xprt_connected(rqst->rq_xprt))
goto drop_connection;
rc = rpcrdma_bc_marshal_reply(rqst);
if (rc < 0)
goto failed_marshal;
if (rpcrdma_ep_post(&r_xprt->rx_ia, &r_xprt->rx_ep, req))
goto drop_connection;
return 0;
failed_marshal:
if (rc != -ENOTCONN)
return rc;
drop_connection:
xprt_disconnect_done(rqst->rq_xprt);
return -ENOTCONN;
}
/**
* xprt_rdma_bc_destroy - Release resources for handling backchannel requests
* @xprt: transport associated with these backchannel resources
* @reqs: number of incoming requests to destroy; ignored
*/
void xprt_rdma_bc_destroy(struct rpc_xprt *xprt, unsigned int reqs)
{
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
struct rpc_rqst *rqst, *tmp;
spin_lock_bh(&xprt->bc_pa_lock);
list_for_each_entry_safe(rqst, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
list_del(&rqst->rq_bc_pa_list);
spin_unlock_bh(&xprt->bc_pa_lock);
rpcrdma_bc_free_rqst(r_xprt, rqst);
spin_lock_bh(&xprt->bc_pa_lock);
}
spin_unlock_bh(&xprt->bc_pa_lock);
}
/**
* xprt_rdma_bc_free_rqst - Release a backchannel rqst
* @rqst: request to release
*/
void xprt_rdma_bc_free_rqst(struct rpc_rqst *rqst)
{
struct rpc_xprt *xprt = rqst->rq_xprt;
dprintk("RPC: %s: freeing rqst %p (req %p)\n",
__func__, rqst, rpcr_to_rdmar(rqst));
spin_lock_bh(&xprt->bc_pa_lock);
list_add_tail(&rqst->rq_bc_pa_list, &xprt->bc_pa_list);
spin_unlock_bh(&xprt->bc_pa_lock);
}
/**
* rpcrdma_bc_receive_call - Handle a backward direction call
* @r_xprt: transport receiving the call
* @rep: receive buffer containing the call
*
* Operational assumptions:
* o Backchannel credits are ignored, just as the NFS server
* forechannel currently does
* o The ULP manages a replay cache (eg, NFSv4.1 sessions).
* No replay detection is done at the transport level
*/
void rpcrdma_bc_receive_call(struct rpcrdma_xprt *r_xprt,
struct rpcrdma_rep *rep)
{
struct rpc_xprt *xprt = &r_xprt->rx_xprt;
struct svc_serv *bc_serv;
struct rpcrdma_req *req;
struct rpc_rqst *rqst;
struct xdr_buf *buf;
size_t size;
__be32 *p;
p = xdr_inline_decode(&rep->rr_stream, 0);
size = xdr_stream_remaining(&rep->rr_stream);
#ifdef RPCRDMA_BACKCHANNEL_DEBUG
pr_info("RPC: %s: callback XID %08x, length=%u\n",
__func__, be32_to_cpup(p), size);
pr_info("RPC: %s: %*ph\n", __func__, size, p);
#endif
/* Grab a free bc rqst */
spin_lock(&xprt->bc_pa_lock);
if (list_empty(&xprt->bc_pa_list)) {
spin_unlock(&xprt->bc_pa_lock);
goto out_overflow;
}
rqst = list_first_entry(&xprt->bc_pa_list,
struct rpc_rqst, rq_bc_pa_list);
list_del(&rqst->rq_bc_pa_list);
spin_unlock(&xprt->bc_pa_lock);
/* Prepare rqst */
rqst->rq_reply_bytes_recvd = 0;
rqst->rq_bytes_sent = 0;
rqst->rq_xid = *p;
rqst->rq_private_buf.len = size;
buf = &rqst->rq_rcv_buf;
memset(buf, 0, sizeof(*buf));
buf->head[0].iov_base = p;
buf->head[0].iov_len = size;
buf->len = size;
/* The receive buffer has to be hooked to the rpcrdma_req
* so that it is not released while the req is pointing
* to its buffer, and so that it can be reposted after
* the Upper Layer is done decoding it.
*/
req = rpcr_to_rdmar(rqst);
req->rl_reply = rep;
trace_xprtrdma_cb_call(rqst);
/* Queue rqst for ULP's callback service */
bc_serv = xprt->bc_serv;
spin_lock(&bc_serv->sv_cb_lock);
list_add(&rqst->rq_bc_list, &bc_serv->sv_cb_list);
spin_unlock(&bc_serv->sv_cb_lock);
wake_up(&bc_serv->sv_cb_waitq);
r_xprt->rx_stats.bcall_count++;
return;
out_overflow:
pr_warn("RPC/RDMA backchannel overflow\n");
xprt_disconnect_done(xprt);
/* This receive buffer gets reposted automatically
* when the connection is re-established.
*/
return;
}
|