Release 4.8 net/sunrpc/xprtrdma/svc_rdma_backchannel.c
/*
* Copyright (c) 2015 Oracle. All rights reserved.
*
* Support for backward direction RPCs on RPC/RDMA (server-side).
*/
#include <linux/sunrpc/svc_rdma.h>
#include "xprt_rdma.h"
#define RPCDBG_FACILITY RPCDBG_SVCXPRT
#undef SVCRDMA_BACKCHANNEL_DEBUG
int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt, struct rpcrdma_msg *rmsgp,
struct xdr_buf *rcvbuf)
{
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
struct kvec *dst, *src = &rcvbuf->head[0];
struct rpc_rqst *req;
unsigned long cwnd;
u32 credits;
size_t len;
__be32 xid;
__be32 *p;
int ret;
p = (__be32 *)src->iov_base;
len = src->iov_len;
xid = rmsgp->rm_xid;
#ifdef SVCRDMA_BACKCHANNEL_DEBUG
pr_info("%s: xid=%08x, length=%zu\n",
__func__, be32_to_cpu(xid), len);
pr_info("%s: RPC/RDMA: %*ph\n",
__func__, (int)RPCRDMA_HDRLEN_MIN, rmsgp);
pr_info("%s: RPC: %*ph\n",
__func__, (int)len, p);
#endif
ret = -EAGAIN;
if (src->iov_len < 24)
goto out_shortreply;
spin_lock_bh(&xprt->transport_lock);
req = xprt_lookup_rqst(xprt, xid);
if (!req)
goto out_notfound;
dst = &req->rq_private_buf.head[0];
memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
if (dst->iov_len < len)
goto out_unlock;
memcpy(dst->iov_base, p, len);
credits = be32_to_cpu(rmsgp->rm_credit);
if (credits == 0)
credits = 1; /* don't deadlock */
else if (credits > r_xprt->rx_buf.rb_bc_max_requests)
credits = r_xprt->rx_buf.rb_bc_max_requests;
cwnd = xprt->cwnd;
xprt->cwnd = credits << RPC_CWNDSHIFT;
if (xprt->cwnd > cwnd)
xprt_release_rqst_cong(req->rq_task);
ret = 0;
xprt_complete_rqst(req->rq_task, rcvbuf->len);
rcvbuf->len = 0;
out_unlock:
spin_unlock_bh(&xprt->transport_lock);
out:
return ret;
out_shortreply:
dprintk("svcrdma: short bc reply: xprt=%p, len=%zu\n",
xprt, src->iov_len);
goto out;
out_notfound:
dprintk("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n",
xprt, be32_to_cpu(xid));
goto out_unlock;
}
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/* Send a backwards direction RPC call.
*
* Caller holds the connection's mutex and has already marshaled
* the RPC/RDMA request.
*
* This is similar to svc_rdma_reply, but takes an rpc_rqst
* instead, does not support chunks, and avoids blocking memory
* allocation.
*
* XXX: There is still an opportunity to block in svc_rdma_send()
* if there are no SQ entries to post the Send. This may occur if
* the adapter has a small maximum SQ depth.
*/
static int svc_rdma_bc_sendto(struct svcxprt_rdma *rdma,
struct rpc_rqst *rqst)
{
struct xdr_buf *sndbuf = &rqst->rq_snd_buf;
struct svc_rdma_op_ctxt *ctxt;
struct svc_rdma_req_map *vec;
struct ib_send_wr send_wr;
int ret;
vec = svc_rdma_get_req_map(rdma);
ret = svc_rdma_map_xdr(rdma, sndbuf, vec, false);
if (ret)
goto out_err;
ret = svc_rdma_repost_recv(rdma, GFP_NOIO);
if (ret)
goto out_err;
ctxt = svc_rdma_get_context(rdma);
ctxt->pages[0] = virt_to_page(rqst->rq_buffer);
ctxt->count = 1;
ctxt->direction = DMA_TO_DEVICE;
ctxt->sge[0].lkey = rdma->sc_pd->local_dma_lkey;
ctxt->sge[0].length = sndbuf->len;
ctxt->sge[0].addr =
ib_dma_map_page(rdma->sc_cm_id->device, ctxt->pages[0], 0,
sndbuf->len, DMA_TO_DEVICE);
if (ib_dma_mapping_error(rdma->sc_cm_id->device, ctxt->sge[0].addr)) {
ret = -EIO;
goto out_unmap;
}
atomic_inc(&rdma->sc_dma_used);
memset(&send_wr, 0, sizeof(send_wr));
ctxt->cqe.done = svc_rdma_wc_send;
send_wr.wr_cqe = &ctxt->cqe;
send_wr.sg_list = ctxt->sge;
send_wr.num_sge = 1;
send_wr.opcode = IB_WR_SEND;
send_wr.send_flags = IB_SEND_SIGNALED;
ret = svc_rdma_send(rdma, &send_wr);
if (ret) {
ret = -EIO;
goto out_unmap;
}
out_err:
svc_rdma_put_req_map(rdma, vec);
dprintk("svcrdma: %s returns %d\n", __func__, ret);
return ret;
out_unmap:
svc_rdma_unmap_dma(ctxt);
svc_rdma_put_context(ctxt, 1);
goto out_err;
}
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/* Server-side transport endpoint wants a whole page for its send
* buffer. The client RPC code constructs the RPC header in this
* buffer before it invokes ->send_request.
*
* Returns NULL if there was a temporary allocation failure.
*/
static void *
xprt_rdma_bc_allocate(struct rpc_task *task, size_t size)
{
struct rpc_rqst *rqst = task->tk_rqstp;
struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
struct svcxprt_rdma *rdma;
struct page *page;
rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
/* Prevent an infinite loop: try to make this case work */
if (size > PAGE_SIZE)
WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
size);
page = alloc_page(RPCRDMA_DEF_GFP);
if (!page)
return NULL;
return page_address(page);
}
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static void
xprt_rdma_bc_free(void *buffer)
{
/* No-op: ctxt and page have already been freed. */
}
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static int
rpcrdma_bc_send_request(struct svcxprt_rdma *rdma, struct rpc_rqst *rqst)
{
struct rpc_xprt *xprt = rqst->rq_xprt;
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
struct rpcrdma_msg *headerp = (struct rpcrdma_msg *)rqst->rq_buffer;
int rc;
/* Space in the send buffer for an RPC/RDMA header is reserved
* via xprt->tsh_size.
*/
headerp->rm_xid = rqst->rq_xid;
headerp->rm_vers = rpcrdma_version;
headerp->rm_credit = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
headerp->rm_type = rdma_msg;
headerp->rm_body.rm_chunks[0] = xdr_zero;
headerp->rm_body.rm_chunks[1] = xdr_zero;
headerp->rm_body.rm_chunks[2] = xdr_zero;
#ifdef SVCRDMA_BACKCHANNEL_DEBUG
pr_info("%s: %*ph\n", __func__, 64, rqst->rq_buffer);
#endif
rc = svc_rdma_bc_sendto(rdma, rqst);
if (rc)
goto drop_connection;
return rc;
drop_connection:
dprintk("svcrdma: failed to send bc call\n");
xprt_disconnect_done(xprt);
return -ENOTCONN;
}
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/* Send an RPC call on the passive end of a transport
* connection.
*/
static int
xprt_rdma_bc_send_request(struct rpc_task *task)
{
struct rpc_rqst *rqst = task->tk_rqstp;
struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
struct svcxprt_rdma *rdma;
int ret;
dprintk("svcrdma: sending bc call with xid: %08x\n",
be32_to_cpu(rqst->rq_xid));
if (!mutex_trylock(&sxprt->xpt_mutex)) {
rpc_sleep_on(&sxprt->xpt_bc_pending, task, NULL);
if (!mutex_trylock(&sxprt->xpt_mutex))
return -EAGAIN;
rpc_wake_up_queued_task(&sxprt->xpt_bc_pending, task);
}
ret = -ENOTCONN;
rdma = container_of(sxprt, struct svcxprt_rdma, sc_xprt);
if (!test_bit(XPT_DEAD, &sxprt->xpt_flags))
ret = rpcrdma_bc_send_request(rdma, rqst);
mutex_unlock(&sxprt->xpt_mutex);
if (ret < 0)
return ret;
return 0;
}
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static void
xprt_rdma_bc_close(struct rpc_xprt *xprt)
{
dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
}
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static void
xprt_rdma_bc_put(struct rpc_xprt *xprt)
{
dprintk("svcrdma: %s: xprt %p\n", __func__, xprt);
xprt_free(xprt);
module_put(THIS_MODULE);
}
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static struct rpc_xprt_ops xprt_rdma_bc_procs = {
.reserve_xprt = xprt_reserve_xprt_cong,
.release_xprt = xprt_release_xprt_cong,
.alloc_slot = xprt_alloc_slot,
.release_request = xprt_release_rqst_cong,
.buf_alloc = xprt_rdma_bc_allocate,
.buf_free = xprt_rdma_bc_free,
.send_request = xprt_rdma_bc_send_request,
.set_retrans_timeout = xprt_set_retrans_timeout_def,
.close = xprt_rdma_bc_close,
.destroy = xprt_rdma_bc_put,
.print_stats = xprt_rdma_print_stats
};
static const struct rpc_timeout xprt_rdma_bc_timeout = {
.to_initval = 60 * HZ,
.to_maxval = 60 * HZ,
};
/* It shouldn't matter if the number of backchannel session slots
* doesn't match the number of RPC/RDMA credits. That just means
* one or the other will have extra slots that aren't used.
*/
static struct rpc_xprt *
xprt_setup_rdma_bc(struct xprt_create *args)
{
struct rpc_xprt *xprt;
struct rpcrdma_xprt *new_xprt;
if (args->addrlen > sizeof(xprt->addr)) {
dprintk("RPC: %s: address too large\n", __func__);
return ERR_PTR(-EBADF);
}
xprt = xprt_alloc(args->net, sizeof(*new_xprt),
RPCRDMA_MAX_BC_REQUESTS,
RPCRDMA_MAX_BC_REQUESTS);
if (!xprt) {
dprintk("RPC: %s: couldn't allocate rpc_xprt\n",
__func__);
return ERR_PTR(-ENOMEM);
}
xprt->timeout = &xprt_rdma_bc_timeout;
xprt_set_bound(xprt);
xprt_set_connected(xprt);
xprt->bind_timeout = RPCRDMA_BIND_TO;
xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO;
xprt->prot = XPRT_TRANSPORT_BC_RDMA;
xprt->tsh_size = RPCRDMA_HDRLEN_MIN / sizeof(__be32);
xprt->ops = &xprt_rdma_bc_procs;
memcpy(&xprt->addr, args->dstaddr, args->addrlen);
xprt->addrlen = args->addrlen;
xprt_rdma_format_addresses(xprt, (struct sockaddr *)&xprt->addr);
xprt->resvport = 0;
xprt->max_payload = xprt_rdma_max_inline_read;
new_xprt = rpcx_to_rdmax(xprt);
new_xprt->rx_buf.rb_bc_max_requests = xprt->max_reqs;
xprt_get(xprt);
args->bc_xprt->xpt_bc_xprt = xprt;
xprt->bc_xprt = args->bc_xprt;
if (!try_module_get(THIS_MODULE))
goto out_fail;
/* Final put for backchannel xprt is in __svc_rdma_free */
xprt_get(xprt);
return xprt;
out_fail:
xprt_rdma_free_addresses(xprt);
args->bc_xprt->xpt_bc_xprt = NULL;
xprt_put(xprt);
xprt_free(xprt);
return ERR_PTR(-EINVAL);
}
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struct xprt_class xprt_rdma_bc = {
.list = LIST_HEAD_INIT(xprt_rdma_bc.list),
.name = "rdma backchannel",
.owner = THIS_MODULE,
.ident = XPRT_TRANSPORT_BC_RDMA,
.setup = xprt_setup_rdma_bc,
};
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