net/sunrpc/xprtrdma/svc_rdma_backchannel.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (c) 2015-2018 Oracle.  All rights reserved.
  *
  * Support for backward direction RPCs on RPC/RDMA (server-side).
  */

 #include <linux/sunrpc/svc_rdma.h>

 #include "xprt_rdma.h"
 #include <trace/events/rpcrdma.h>

 /**
  * svc_rdma_handle_bc_reply - Process incoming backchannel Reply
  * @rqstp: resources for handling the Reply
  * @rctxt: Received message
  *
  */
 void svc_rdma_handle_bc_reply(struct svc_rqst *rqstp,
 			      struct svc_rdma_recv_ctxt *rctxt)
 {
 	struct svc_xprt *sxprt = rqstp->rq_xprt;
 	struct rpc_xprt *xprt = sxprt->xpt_bc_xprt;
 	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
 	struct xdr_buf *rcvbuf = &rqstp->rq_arg;
 	struct kvec *dst, *src = &rcvbuf->head[0];
 	__be32 *rdma_resp = rctxt->rc_recv_buf;
 	struct rpc_rqst *req;
 	u32 credits;

 	spin_lock(&xprt->queue_lock);
 	req = xprt_lookup_rqst(xprt, *rdma_resp);
 	if (!req)
 		goto out_unlock;

 	dst = &req->rq_private_buf.head[0];
 	memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
 	if (dst->iov_len < src->iov_len)
 		goto out_unlock;
 	memcpy(dst->iov_base, src->iov_base, src->iov_len);
 	xprt_pin_rqst(req);
 	spin_unlock(&xprt->queue_lock);

 	credits = be32_to_cpup(rdma_resp + 2);
 	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;
 	spin_lock(&xprt->transport_lock);
 	xprt->cwnd = credits << RPC_CWNDSHIFT;
 	spin_unlock(&xprt->transport_lock);

 	spin_lock(&xprt->queue_lock);
 	xprt_complete_rqst(req->rq_task, rcvbuf->len);
 	xprt_unpin_rqst(req);
 	rcvbuf->len = 0;

 out_unlock:
 	spin_unlock(&xprt->queue_lock);
 }

 /* 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_send_reply_msg, but takes a struct
  * 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 svc_rdma_send_ctxt *ctxt)
 {
 	int ret;

 	ret = svc_rdma_map_reply_msg(rdma, ctxt, NULL, &rqst->rq_snd_buf);
 	if (ret < 0)
 		return -EIO;

 	/* Bump page refcnt so Send completion doesn't release
 	 * the rq_buffer before all retransmits are complete.
 	 */
 	get_page(virt_to_page(rqst->rq_buffer));
 	ctxt->sc_send_wr.opcode = IB_WR_SEND;
 	return svc_rdma_send(rdma, &ctxt->sc_send_wr);
 }

 /* 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.
  */
 static int
 xprt_rdma_bc_allocate(struct rpc_task *task)
 {
 	struct rpc_rqst *rqst = task->tk_rqstp;
 	size_t size = rqst->rq_callsize;
 	struct page *page;

 	if (size > PAGE_SIZE) {
 		WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
 			  size);
 		return -EINVAL;
 	}

 	page = alloc_page(RPCRDMA_DEF_GFP);
 	if (!page)
 		return -ENOMEM;
 	rqst->rq_buffer = page_address(page);

 	rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
 	if (!rqst->rq_rbuffer) {
 		put_page(page);
 		return -ENOMEM;
 	}
 	return 0;
 }

 static void
 xprt_rdma_bc_free(struct rpc_task *task)
 {
 	struct rpc_rqst *rqst = task->tk_rqstp;

 	put_page(virt_to_page(rqst->rq_buffer));
 	kfree(rqst->rq_rbuffer);
 }

 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 svc_rdma_send_ctxt *ctxt;
 	__be32 *p;
 	int rc;

 	ctxt = svc_rdma_send_ctxt_get(rdma);
 	if (!ctxt)
 		goto drop_connection;

 	p = xdr_reserve_space(&ctxt->sc_stream, RPCRDMA_HDRLEN_MIN);
 	if (!p)
 		goto put_ctxt;
 	*p++ = rqst->rq_xid;
 	*p++ = rpcrdma_version;
 	*p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
 	*p++ = rdma_msg;
 	*p++ = xdr_zero;
 	*p++ = xdr_zero;
 	*p   = xdr_zero;

 	rqst->rq_xtime = ktime_get();
 	rc = svc_rdma_bc_sendto(rdma, rqst, ctxt);
 	if (rc)
 		goto put_ctxt;
 	return 0;

 put_ctxt:
 	svc_rdma_send_ctxt_put(rdma, ctxt);

 drop_connection:
 	return -ENOTCONN;
 }

 /**
  * xprt_rdma_bc_send_request - Send a reverse-direction Call
  * @rqst: rpc_rqst containing Call message to be sent
  *
  * Return values:
  *   %0 if the message was sent successfully
  *   %ENOTCONN if the message was not sent
  */
 static int xprt_rdma_bc_send_request(struct rpc_rqst *rqst)
 {
 	struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
 	struct svcxprt_rdma *rdma =
 		container_of(sxprt, struct svcxprt_rdma, sc_xprt);
 	int ret;

 	if (test_bit(XPT_DEAD, &sxprt->xpt_flags))
 		return -ENOTCONN;

 	ret = rpcrdma_bc_send_request(rdma, rqst);
 	if (ret == -ENOTCONN)
 		svc_close_xprt(sxprt);
 	return ret;
 }

 static void
 xprt_rdma_bc_close(struct rpc_xprt *xprt)
 {
 	xprt_disconnect_done(xprt);
 	xprt->cwnd = RPC_CWNDSHIFT;
 }

 static void
 xprt_rdma_bc_put(struct rpc_xprt *xprt)
 {
 	xprt_rdma_free_addresses(xprt);
 	xprt_free(xprt);
 }

 static const 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,
 	.free_slot		= xprt_free_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,
 	.wait_for_reply_request	= xprt_wait_for_reply_request_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))
 		return ERR_PTR(-EBADF);

 	xprt = xprt_alloc(args->net, sizeof(*new_xprt),
 			  RPCRDMA_MAX_BC_REQUESTS,
 			  RPCRDMA_MAX_BC_REQUESTS);
 	if (!xprt)
 		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->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;

 	/* Final put for backchannel xprt is in __svc_rdma_free */
 	xprt_get(xprt);
 	return xprt;
 }

 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,
 };
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Copyright (c) 2015-2018 Oracle. All rights reserved.
	*
	* Support for backward direction RPCs on RPC/RDMA (server-side).
	*/

	#include <linux/sunrpc/svc_rdma.h>

	#include "xprt_rdma.h"
	#include <trace/events/rpcrdma.h>

	/**
	* svc_rdma_handle_bc_reply - Process incoming backchannel Reply
	* @rqstp: resources for handling the Reply
	* @rctxt: Received message
	*
	*/
	void svc_rdma_handle_bc_reply(struct svc_rqst *rqstp,
	struct svc_rdma_recv_ctxt *rctxt)
	{
	struct svc_xprt *sxprt = rqstp->rq_xprt;
	struct rpc_xprt *xprt = sxprt->xpt_bc_xprt;
	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
	struct xdr_buf *rcvbuf = &rqstp->rq_arg;
	struct kvec dst, src = &rcvbuf->head[0];
	__be32 *rdma_resp = rctxt->rc_recv_buf;
	struct rpc_rqst *req;
	u32 credits;

	spin_lock(&xprt->queue_lock);
	req = xprt_lookup_rqst(xprt, *rdma_resp);
	if (!req)
	goto out_unlock;

	dst = &req->rq_private_buf.head[0];
	memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf));
	if (dst->iov_len < src->iov_len)
	goto out_unlock;
	memcpy(dst->iov_base, src->iov_base, src->iov_len);
	xprt_pin_rqst(req);
	spin_unlock(&xprt->queue_lock);

	credits = be32_to_cpup(rdma_resp + 2);
	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;
	spin_lock(&xprt->transport_lock);
	xprt->cwnd = credits << RPC_CWNDSHIFT;
	spin_unlock(&xprt->transport_lock);

	spin_lock(&xprt->queue_lock);
	xprt_complete_rqst(req->rq_task, rcvbuf->len);
	xprt_unpin_rqst(req);
	rcvbuf->len = 0;

	out_unlock:
	spin_unlock(&xprt->queue_lock);
	}

	/* 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_send_reply_msg, but takes a struct
	* 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 svc_rdma_send_ctxt *ctxt)
	{
	int ret;

	ret = svc_rdma_map_reply_msg(rdma, ctxt, NULL, &rqst->rq_snd_buf);
	if (ret < 0)
	return -EIO;

	/* Bump page refcnt so Send completion doesn't release
	* the rq_buffer before all retransmits are complete.
	*/
	get_page(virt_to_page(rqst->rq_buffer));
	ctxt->sc_send_wr.opcode = IB_WR_SEND;
	return svc_rdma_send(rdma, &ctxt->sc_send_wr);
	}

	/* 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.
	*/
	static int
	xprt_rdma_bc_allocate(struct rpc_task *task)
	{
	struct rpc_rqst *rqst = task->tk_rqstp;
	size_t size = rqst->rq_callsize;
	struct page *page;

	if (size > PAGE_SIZE) {
	WARN_ONCE(1, "svcrdma: large bc buffer request (size %zu)\n",
	size);
	return -EINVAL;
	}

	page = alloc_page(RPCRDMA_DEF_GFP);
	if (!page)
	return -ENOMEM;
	rqst->rq_buffer = page_address(page);

	rqst->rq_rbuffer = kmalloc(rqst->rq_rcvsize, RPCRDMA_DEF_GFP);
	if (!rqst->rq_rbuffer) {
	put_page(page);
	return -ENOMEM;
	}
	return 0;
	}

	static void
	xprt_rdma_bc_free(struct rpc_task *task)
	{
	struct rpc_rqst *rqst = task->tk_rqstp;

	put_page(virt_to_page(rqst->rq_buffer));
	kfree(rqst->rq_rbuffer);
	}

	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 svc_rdma_send_ctxt *ctxt;
	__be32 *p;
	int rc;

	ctxt = svc_rdma_send_ctxt_get(rdma);
	if (!ctxt)
	goto drop_connection;

	p = xdr_reserve_space(&ctxt->sc_stream, RPCRDMA_HDRLEN_MIN);
	if (!p)
	goto put_ctxt;
	*p++ = rqst->rq_xid;
	*p++ = rpcrdma_version;
	*p++ = cpu_to_be32(r_xprt->rx_buf.rb_bc_max_requests);
	*p++ = rdma_msg;
	*p++ = xdr_zero;
	*p++ = xdr_zero;
	*p = xdr_zero;

	rqst->rq_xtime = ktime_get();
	rc = svc_rdma_bc_sendto(rdma, rqst, ctxt);
	if (rc)
	goto put_ctxt;
	return 0;

	put_ctxt:
	svc_rdma_send_ctxt_put(rdma, ctxt);

	drop_connection:
	return -ENOTCONN;
	}

	/**
	* xprt_rdma_bc_send_request - Send a reverse-direction Call
	* @rqst: rpc_rqst containing Call message to be sent
	*
	* Return values:
	* %0 if the message was sent successfully
	* %ENOTCONN if the message was not sent
	*/
	static int xprt_rdma_bc_send_request(struct rpc_rqst *rqst)
	{
	struct svc_xprt *sxprt = rqst->rq_xprt->bc_xprt;
	struct svcxprt_rdma *rdma =
	container_of(sxprt, struct svcxprt_rdma, sc_xprt);
	int ret;

	if (test_bit(XPT_DEAD, &sxprt->xpt_flags))
	return -ENOTCONN;

	ret = rpcrdma_bc_send_request(rdma, rqst);
	if (ret == -ENOTCONN)
	svc_close_xprt(sxprt);
	return ret;
	}

	static void
	xprt_rdma_bc_close(struct rpc_xprt *xprt)
	{
	xprt_disconnect_done(xprt);
	xprt->cwnd = RPC_CWNDSHIFT;
	}

	static void
	xprt_rdma_bc_put(struct rpc_xprt *xprt)
	{
	xprt_rdma_free_addresses(xprt);
	xprt_free(xprt);
	}

	static const 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,
	.free_slot = xprt_free_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,
	.wait_for_reply_request = xprt_wait_for_reply_request_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))
	return ERR_PTR(-EBADF);

	xprt = xprt_alloc(args->net, sizeof(*new_xprt),
	RPCRDMA_MAX_BC_REQUESTS,
	RPCRDMA_MAX_BC_REQUESTS);
	if (!xprt)
	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->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;

	/* Final put for backchannel xprt is in __svc_rdma_free */
	xprt_get(xprt);
	return xprt;
	}

	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,
	};