Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1572 insertions, 0 deletions

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
new file mode 100644
index 000000000..ef1f3d076
--- /dev/null
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -0,0 +1,1572 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+/*
+ * Copyright (c) 2014-2017 Oracle.  All rights reserved.
+ * Copyright (c) 2003-2007 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.
+ */
+
+/*
+ * verbs.c
+ *
+ * Encapsulates the major functions managing:
+ *  o adapters
+ *  o endpoints
+ *  o connections
+ *  o buffer memory
+ */
+
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/sunrpc/addr.h>
+#include <linux/sunrpc/svc_rdma.h>
+
+#include <asm-generic/barrier.h>
+#include <asm/bitops.h>
+
+#include <rdma/ib_cm.h>
+
+#include "xprt_rdma.h"
+#include <trace/events/rpcrdma.h>
+
+/*
+ * Globals/Macros
+ */
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+# define RPCDBG_FACILITY	RPCDBG_TRANS
+#endif
+
+/*
+ * internal functions
+ */
+static void rpcrdma_sendctx_put_locked(struct rpcrdma_sendctx *sc);
+static void rpcrdma_mrs_create(struct rpcrdma_xprt *r_xprt);
+static void rpcrdma_mrs_destroy(struct rpcrdma_buffer *buf);
+static int rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt, bool temp);
+static void rpcrdma_dma_unmap_regbuf(struct rpcrdma_regbuf *rb);
+
+struct workqueue_struct *rpcrdma_receive_wq __read_mostly;
+
+int
+rpcrdma_alloc_wq(void)
+{
+	struct workqueue_struct *recv_wq;
+
+	recv_wq = alloc_workqueue("xprtrdma_receive",
+				  WQ_MEM_RECLAIM | WQ_HIGHPRI,
+				  0);
+	if (!recv_wq)
+		return -ENOMEM;
+
+	rpcrdma_receive_wq = recv_wq;
+	return 0;
+}
+
+void
+rpcrdma_destroy_wq(void)
+{
+	struct workqueue_struct *wq;
+
+	if (rpcrdma_receive_wq) {
+		wq = rpcrdma_receive_wq;
+		rpcrdma_receive_wq = NULL;
+		destroy_workqueue(wq);
+	}
+}
+
+static void
+rpcrdma_qp_async_error_upcall(struct ib_event *event, void *context)
+{
+	struct rpcrdma_ep *ep = context;
+	struct rpcrdma_xprt *r_xprt = container_of(ep, struct rpcrdma_xprt,
+						   rx_ep);
+
+	trace_xprtrdma_qp_error(r_xprt, event);
+	pr_err("rpcrdma: %s on device %s ep %p\n",
+	       ib_event_msg(event->event), event->device->name, context);
+
+	if (ep->rep_connected == 1) {
+		ep->rep_connected = -EIO;
+		rpcrdma_conn_func(ep);
+		wake_up_all(&ep->rep_connect_wait);
+	}
+}
+
+/**
+ * rpcrdma_wc_send - Invoked by RDMA provider for each polled Send WC
+ * @cq:	completion queue (ignored)
+ * @wc:	completed WR
+ *
+ */
+static void
+rpcrdma_wc_send(struct ib_cq *cq, struct ib_wc *wc)
+{
+	struct ib_cqe *cqe = wc->wr_cqe;
+	struct rpcrdma_sendctx *sc =
+		container_of(cqe, struct rpcrdma_sendctx, sc_cqe);
+
+	/* WARNING: Only wr_cqe and status are reliable at this point */
+	trace_xprtrdma_wc_send(sc, wc);
+	if (wc->status != IB_WC_SUCCESS && wc->status != IB_WC_WR_FLUSH_ERR)
+		pr_err("rpcrdma: Send: %s (%u/0x%x)\n",
+		       ib_wc_status_msg(wc->status),
+		       wc->status, wc->vendor_err);
+
+	rpcrdma_sendctx_put_locked(sc);
+}
+
+/**
+ * rpcrdma_wc_receive - Invoked by RDMA provider for each polled Receive WC
+ * @cq:	completion queue (ignored)
+ * @wc:	completed WR
+ *
+ */
+static void
+rpcrdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc)
+{
+	struct ib_cqe *cqe = wc->wr_cqe;
+	struct rpcrdma_rep *rep = container_of(cqe, struct rpcrdma_rep,
+					       rr_cqe);
+
+	/* WARNING: Only wr_id and status are reliable at this point */
+	trace_xprtrdma_wc_receive(wc);
+	if (wc->status != IB_WC_SUCCESS)
+		goto out_fail;
+
+	/* status == SUCCESS means all fields in wc are trustworthy */
+	rpcrdma_set_xdrlen(&rep->rr_hdrbuf, wc->byte_len);
+	rep->rr_wc_flags = wc->wc_flags;
+	rep->rr_inv_rkey = wc->ex.invalidate_rkey;
+
+	ib_dma_sync_single_for_cpu(rdmab_device(rep->rr_rdmabuf),
+				   rdmab_addr(rep->rr_rdmabuf),
+				   wc->byte_len, DMA_FROM_DEVICE);
+
+out_schedule:
+	rpcrdma_reply_handler(rep);
+	return;
+
+out_fail:
+	if (wc->status != IB_WC_WR_FLUSH_ERR)
+		pr_err("rpcrdma: Recv: %s (%u/0x%x)\n",
+		       ib_wc_status_msg(wc->status),
+		       wc->status, wc->vendor_err);
+	rpcrdma_set_xdrlen(&rep->rr_hdrbuf, 0);
+	goto out_schedule;
+}
+
+static void
+rpcrdma_update_connect_private(struct rpcrdma_xprt *r_xprt,
+			       struct rdma_conn_param *param)
+{
+	struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
+	const struct rpcrdma_connect_private *pmsg = param->private_data;
+	unsigned int rsize, wsize;
+
+	/* Default settings for RPC-over-RDMA Version One */
+	r_xprt->rx_ia.ri_implicit_roundup = xprt_rdma_pad_optimize;
+	rsize = RPCRDMA_V1_DEF_INLINE_SIZE;
+	wsize = RPCRDMA_V1_DEF_INLINE_SIZE;
+
+	if (pmsg &&
+	    pmsg->cp_magic == rpcrdma_cmp_magic &&
+	    pmsg->cp_version == RPCRDMA_CMP_VERSION) {
+		r_xprt->rx_ia.ri_implicit_roundup = true;
+		rsize = rpcrdma_decode_buffer_size(pmsg->cp_send_size);
+		wsize = rpcrdma_decode_buffer_size(pmsg->cp_recv_size);
+	}
+
+	if (rsize < cdata->inline_rsize)
+		cdata->inline_rsize = rsize;
+	if (wsize < cdata->inline_wsize)
+		cdata->inline_wsize = wsize;
+	dprintk("RPC:       %s: max send %u, max recv %u\n",
+		__func__, cdata->inline_wsize, cdata->inline_rsize);
+	rpcrdma_set_max_header_sizes(r_xprt);
+}
+
+static int
+rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event)
+{
+	struct rpcrdma_xprt *xprt = id->context;
+	struct rpcrdma_ia *ia = &xprt->rx_ia;
+	struct rpcrdma_ep *ep = &xprt->rx_ep;
+	int connstate = 0;
+
+	trace_xprtrdma_conn_upcall(xprt, event);
+	switch (event->event) {
+	case RDMA_CM_EVENT_ADDR_RESOLVED:
+	case RDMA_CM_EVENT_ROUTE_RESOLVED:
+		ia->ri_async_rc = 0;
+		complete(&ia->ri_done);
+		break;
+	case RDMA_CM_EVENT_ADDR_ERROR:
+		ia->ri_async_rc = -EPROTO;
+		complete(&ia->ri_done);
+		break;
+	case RDMA_CM_EVENT_ROUTE_ERROR:
+		ia->ri_async_rc = -ENETUNREACH;
+		complete(&ia->ri_done);
+		break;
+	case RDMA_CM_EVENT_DEVICE_REMOVAL:
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+		pr_info("rpcrdma: removing device %s for %s:%s\n",
+			ia->ri_device->name,
+			rpcrdma_addrstr(xprt), rpcrdma_portstr(xprt));
+#endif
+		init_completion(&ia->ri_remove_done);
+		set_bit(RPCRDMA_IAF_REMOVING, &ia->ri_flags);
+		ep->rep_connected = -ENODEV;
+		xprt_force_disconnect(&xprt->rx_xprt);
+		wait_for_completion(&ia->ri_remove_done);
+
+		ia->ri_id = NULL;
+		ia->ri_device = NULL;
+		/* Return 1 to ensure the core destroys the id. */
+		return 1;
+	case RDMA_CM_EVENT_ESTABLISHED:
+		++xprt->rx_xprt.connect_cookie;
+		connstate = 1;
+		rpcrdma_update_connect_private(xprt, &event->param.conn);
+		goto connected;
+	case RDMA_CM_EVENT_CONNECT_ERROR:
+		connstate = -ENOTCONN;
+		goto connected;
+	case RDMA_CM_EVENT_UNREACHABLE:
+		connstate = -ENETUNREACH;
+		goto connected;
+	case RDMA_CM_EVENT_REJECTED:
+		dprintk("rpcrdma: connection to %s:%s rejected: %s\n",
+			rpcrdma_addrstr(xprt), rpcrdma_portstr(xprt),
+			rdma_reject_msg(id, event->status));
+		connstate = -ECONNREFUSED;
+		if (event->status == IB_CM_REJ_STALE_CONN)
+			connstate = -EAGAIN;
+		goto connected;
+	case RDMA_CM_EVENT_DISCONNECTED:
+		++xprt->rx_xprt.connect_cookie;
+		connstate = -ECONNABORTED;
+connected:
+		ep->rep_connected = connstate;
+		rpcrdma_conn_func(ep);
+		wake_up_all(&ep->rep_connect_wait);
+		/*FALLTHROUGH*/
+	default:
+		dprintk("RPC:       %s: %s:%s on %s/%s (ep 0x%p): %s\n",
+			__func__,
+			rpcrdma_addrstr(xprt), rpcrdma_portstr(xprt),
+			ia->ri_device->name, ia->ri_ops->ro_displayname,
+			ep, rdma_event_msg(event->event));
+		break;
+	}
+
+	return 0;
+}
+
+static struct rdma_cm_id *
+rpcrdma_create_id(struct rpcrdma_xprt *xprt, struct rpcrdma_ia *ia)
+{
+	unsigned long wtimeout = msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT) + 1;
+	struct rdma_cm_id *id;
+	int rc;
+
+	trace_xprtrdma_conn_start(xprt);
+
+	init_completion(&ia->ri_done);
+
+	id = rdma_create_id(xprt->rx_xprt.xprt_net, rpcrdma_conn_upcall,
+			    xprt, RDMA_PS_TCP, IB_QPT_RC);
+	if (IS_ERR(id)) {
+		rc = PTR_ERR(id);
+		dprintk("RPC:       %s: rdma_create_id() failed %i\n",
+			__func__, rc);
+		return id;
+	}
+
+	ia->ri_async_rc = -ETIMEDOUT;
+	rc = rdma_resolve_addr(id, NULL,
+			       (struct sockaddr *)&xprt->rx_xprt.addr,
+			       RDMA_RESOLVE_TIMEOUT);
+	if (rc) {
+		dprintk("RPC:       %s: rdma_resolve_addr() failed %i\n",
+			__func__, rc);
+		goto out;
+	}
+	rc = wait_for_completion_interruptible_timeout(&ia->ri_done, wtimeout);
+	if (rc < 0) {
+		trace_xprtrdma_conn_tout(xprt);
+		goto out;
+	}
+
+	rc = ia->ri_async_rc;
+	if (rc)
+		goto out;
+
+	ia->ri_async_rc = -ETIMEDOUT;
+	rc = rdma_resolve_route(id, RDMA_RESOLVE_TIMEOUT);
+	if (rc) {
+		dprintk("RPC:       %s: rdma_resolve_route() failed %i\n",
+			__func__, rc);
+		goto out;
+	}
+	rc = wait_for_completion_interruptible_timeout(&ia->ri_done, wtimeout);
+	if (rc < 0) {
+		trace_xprtrdma_conn_tout(xprt);
+		goto out;
+	}
+	rc = ia->ri_async_rc;
+	if (rc)
+		goto out;
+
+	return id;
+
+out:
+	rdma_destroy_id(id);
+	return ERR_PTR(rc);
+}
+
+/*
+ * Exported functions.
+ */
+
+/**
+ * rpcrdma_ia_open - Open and initialize an Interface Adapter.
+ * @xprt: transport with IA to (re)initialize
+ *
+ * Returns 0 on success, negative errno if an appropriate
+ * Interface Adapter could not be found and opened.
+ */
+int
+rpcrdma_ia_open(struct rpcrdma_xprt *xprt)
+{
+	struct rpcrdma_ia *ia = &xprt->rx_ia;
+	int rc;
+
+	ia->ri_id = rpcrdma_create_id(xprt, ia);
+	if (IS_ERR(ia->ri_id)) {
+		rc = PTR_ERR(ia->ri_id);
+		goto out_err;
+	}
+	ia->ri_device = ia->ri_id->device;
+
+	ia->ri_pd = ib_alloc_pd(ia->ri_device, 0);
+	if (IS_ERR(ia->ri_pd)) {
+		rc = PTR_ERR(ia->ri_pd);
+		pr_err("rpcrdma: ib_alloc_pd() returned %d\n", rc);
+		goto out_err;
+	}
+
+	switch (xprt_rdma_memreg_strategy) {
+	case RPCRDMA_FRWR:
+		if (frwr_is_supported(ia)) {
+			ia->ri_ops = &rpcrdma_frwr_memreg_ops;
+			break;
+		}
+		/*FALLTHROUGH*/
+	case RPCRDMA_MTHCAFMR:
+		if (fmr_is_supported(ia)) {
+			ia->ri_ops = &rpcrdma_fmr_memreg_ops;
+			break;
+		}
+		/*FALLTHROUGH*/
+	default:
+		pr_err("rpcrdma: Device %s does not support memreg mode %d\n",
+		       ia->ri_device->name, xprt_rdma_memreg_strategy);
+		rc = -EINVAL;
+		goto out_err;
+	}
+
+	return 0;
+
+out_err:
+	rpcrdma_ia_close(ia);
+	return rc;
+}
+
+/**
+ * rpcrdma_ia_remove - Handle device driver unload
+ * @ia: interface adapter being removed
+ *
+ * Divest transport H/W resources associated with this adapter,
+ * but allow it to be restored later.
+ */
+void
+rpcrdma_ia_remove(struct rpcrdma_ia *ia)
+{
+	struct rpcrdma_xprt *r_xprt = container_of(ia, struct rpcrdma_xprt,
+						   rx_ia);
+	struct rpcrdma_ep *ep = &r_xprt->rx_ep;
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_req *req;
+	struct rpcrdma_rep *rep;
+
+	cancel_delayed_work_sync(&buf->rb_refresh_worker);
+
+	/* This is similar to rpcrdma_ep_destroy, but:
+	 * - Don't cancel the connect worker.
+	 * - Don't call rpcrdma_ep_disconnect, which waits
+	 *   for another conn upcall, which will deadlock.
+	 * - rdma_disconnect is unneeded, the underlying
+	 *   connection is already gone.
+	 */
+	if (ia->ri_id->qp) {
+		ib_drain_qp(ia->ri_id->qp);
+		rdma_destroy_qp(ia->ri_id);
+		ia->ri_id->qp = NULL;
+	}
+	ib_free_cq(ep->rep_attr.recv_cq);
+	ep->rep_attr.recv_cq = NULL;
+	ib_free_cq(ep->rep_attr.send_cq);
+	ep->rep_attr.send_cq = NULL;
+
+	/* The ULP is responsible for ensuring all DMA
+	 * mappings and MRs are gone.
+	 */
+	list_for_each_entry(rep, &buf->rb_recv_bufs, rr_list)
+		rpcrdma_dma_unmap_regbuf(rep->rr_rdmabuf);
+	list_for_each_entry(req, &buf->rb_allreqs, rl_all) {
+		rpcrdma_dma_unmap_regbuf(req->rl_rdmabuf);
+		rpcrdma_dma_unmap_regbuf(req->rl_sendbuf);
+		rpcrdma_dma_unmap_regbuf(req->rl_recvbuf);
+	}
+	rpcrdma_mrs_destroy(buf);
+	ib_dealloc_pd(ia->ri_pd);
+	ia->ri_pd = NULL;
+
+	/* Allow waiters to continue */
+	complete(&ia->ri_remove_done);
+
+	trace_xprtrdma_remove(r_xprt);
+}
+
+/**
+ * rpcrdma_ia_close - Clean up/close an IA.
+ * @ia: interface adapter to close
+ *
+ */
+void
+rpcrdma_ia_close(struct rpcrdma_ia *ia)
+{
+	if (ia->ri_id != NULL && !IS_ERR(ia->ri_id)) {
+		if (ia->ri_id->qp)
+			rdma_destroy_qp(ia->ri_id);
+		rdma_destroy_id(ia->ri_id);
+	}
+	ia->ri_id = NULL;
+	ia->ri_device = NULL;
+
+	/* If the pd is still busy, xprtrdma missed freeing a resource */
+	if (ia->ri_pd && !IS_ERR(ia->ri_pd))
+		ib_dealloc_pd(ia->ri_pd);
+	ia->ri_pd = NULL;
+}
+
+/*
+ * Create unconnected endpoint.
+ */
+int
+rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
+		  struct rpcrdma_create_data_internal *cdata)
+{
+	struct rpcrdma_connect_private *pmsg = &ep->rep_cm_private;
+	struct ib_cq *sendcq, *recvcq;
+	unsigned int max_sge;
+	int rc;
+
+	max_sge = min_t(unsigned int, ia->ri_device->attrs.max_send_sge,
+			RPCRDMA_MAX_SEND_SGES);
+	if (max_sge < RPCRDMA_MIN_SEND_SGES) {
+		pr_warn("rpcrdma: HCA provides only %d send SGEs\n", max_sge);
+		return -ENOMEM;
+	}
+	ia->ri_max_send_sges = max_sge;
+
+	rc = ia->ri_ops->ro_open(ia, ep, cdata);
+	if (rc)
+		return rc;
+
+	ep->rep_attr.event_handler = rpcrdma_qp_async_error_upcall;
+	ep->rep_attr.qp_context = ep;
+	ep->rep_attr.srq = NULL;
+	ep->rep_attr.cap.max_send_sge = max_sge;
+	ep->rep_attr.cap.max_recv_sge = 1;
+	ep->rep_attr.cap.max_inline_data = 0;
+	ep->rep_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
+	ep->rep_attr.qp_type = IB_QPT_RC;
+	ep->rep_attr.port_num = ~0;
+
+	dprintk("RPC:       %s: requested max: dtos: send %d recv %d; "
+		"iovs: send %d recv %d\n",
+		__func__,
+		ep->rep_attr.cap.max_send_wr,
+		ep->rep_attr.cap.max_recv_wr,
+		ep->rep_attr.cap.max_send_sge,
+		ep->rep_attr.cap.max_recv_sge);
+
+	/* set trigger for requesting send completion */
+	ep->rep_send_batch = min_t(unsigned int, RPCRDMA_MAX_SEND_BATCH,
+				   cdata->max_requests >> 2);
+	ep->rep_send_count = ep->rep_send_batch;
+	init_waitqueue_head(&ep->rep_connect_wait);
+	INIT_DELAYED_WORK(&ep->rep_connect_worker, rpcrdma_connect_worker);
+
+	sendcq = ib_alloc_cq(ia->ri_device, NULL,
+			     ep->rep_attr.cap.max_send_wr + 1,
+			     ia->ri_device->num_comp_vectors > 1 ? 1 : 0,
+			     IB_POLL_WORKQUEUE);
+	if (IS_ERR(sendcq)) {
+		rc = PTR_ERR(sendcq);
+		dprintk("RPC:       %s: failed to create send CQ: %i\n",
+			__func__, rc);
+		goto out1;
+	}
+
+	recvcq = ib_alloc_cq(ia->ri_device, NULL,
+			     ep->rep_attr.cap.max_recv_wr + 1,
+			     0, IB_POLL_WORKQUEUE);
+	if (IS_ERR(recvcq)) {
+		rc = PTR_ERR(recvcq);
+		dprintk("RPC:       %s: failed to create recv CQ: %i\n",
+			__func__, rc);
+		goto out2;
+	}
+
+	ep->rep_attr.send_cq = sendcq;
+	ep->rep_attr.recv_cq = recvcq;
+
+	/* Initialize cma parameters */
+	memset(&ep->rep_remote_cma, 0, sizeof(ep->rep_remote_cma));
+
+	/* Prepare RDMA-CM private message */
+	pmsg->cp_magic = rpcrdma_cmp_magic;
+	pmsg->cp_version = RPCRDMA_CMP_VERSION;
+	pmsg->cp_flags |= ia->ri_ops->ro_send_w_inv_ok;
+	pmsg->cp_send_size = rpcrdma_encode_buffer_size(cdata->inline_wsize);
+	pmsg->cp_recv_size = rpcrdma_encode_buffer_size(cdata->inline_rsize);
+	ep->rep_remote_cma.private_data = pmsg;
+	ep->rep_remote_cma.private_data_len = sizeof(*pmsg);
+
+	/* Client offers RDMA Read but does not initiate */
+	ep->rep_remote_cma.initiator_depth = 0;
+	ep->rep_remote_cma.responder_resources =
+		min_t(int, U8_MAX, ia->ri_device->attrs.max_qp_rd_atom);
+
+	/* Limit transport retries so client can detect server
+	 * GID changes quickly. RPC layer handles re-establishing
+	 * transport connection and retransmission.
+	 */
+	ep->rep_remote_cma.retry_count = 6;
+
+	/* RPC-over-RDMA handles its own flow control. In addition,
+	 * make all RNR NAKs visible so we know that RPC-over-RDMA
+	 * flow control is working correctly (no NAKs should be seen).
+	 */
+	ep->rep_remote_cma.flow_control = 0;
+	ep->rep_remote_cma.rnr_retry_count = 0;
+
+	return 0;
+
+out2:
+	ib_free_cq(sendcq);
+out1:
+	return rc;
+}
+
+/*
+ * rpcrdma_ep_destroy
+ *
+ * Disconnect and destroy endpoint. After this, the only
+ * valid operations on the ep are to free it (if dynamically
+ * allocated) or re-create it.
+ */
+void
+rpcrdma_ep_destroy(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
+{
+	cancel_delayed_work_sync(&ep->rep_connect_worker);
+
+	if (ia->ri_id && ia->ri_id->qp) {
+		rpcrdma_ep_disconnect(ep, ia);
+		rdma_destroy_qp(ia->ri_id);
+		ia->ri_id->qp = NULL;
+	}
+
+	if (ep->rep_attr.recv_cq)
+		ib_free_cq(ep->rep_attr.recv_cq);
+	if (ep->rep_attr.send_cq)
+		ib_free_cq(ep->rep_attr.send_cq);
+}
+
+/* Re-establish a connection after a device removal event.
+ * Unlike a normal reconnection, a fresh PD and a new set
+ * of MRs and buffers is needed.
+ */
+static int
+rpcrdma_ep_recreate_xprt(struct rpcrdma_xprt *r_xprt,
+			 struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
+{
+	int rc, err;
+
+	trace_xprtrdma_reinsert(r_xprt);
+
+	rc = -EHOSTUNREACH;
+	if (rpcrdma_ia_open(r_xprt))
+		goto out1;
+
+	rc = -ENOMEM;
+	err = rpcrdma_ep_create(ep, ia, &r_xprt->rx_data);
+	if (err) {
+		pr_err("rpcrdma: rpcrdma_ep_create returned %d\n", err);
+		goto out2;
+	}
+
+	rc = -ENETUNREACH;
+	err = rdma_create_qp(ia->ri_id, ia->ri_pd, &ep->rep_attr);
+	if (err) {
+		pr_err("rpcrdma: rdma_create_qp returned %d\n", err);
+		goto out3;
+	}
+
+	rpcrdma_mrs_create(r_xprt);
+	return 0;
+
+out3:
+	rpcrdma_ep_destroy(ep, ia);
+out2:
+	rpcrdma_ia_close(ia);
+out1:
+	return rc;
+}
+
+static int
+rpcrdma_ep_reconnect(struct rpcrdma_xprt *r_xprt, struct rpcrdma_ep *ep,
+		     struct rpcrdma_ia *ia)
+{
+	struct rdma_cm_id *id, *old;
+	int err, rc;
+
+	trace_xprtrdma_reconnect(r_xprt);
+
+	rpcrdma_ep_disconnect(ep, ia);
+
+	rc = -EHOSTUNREACH;
+	id = rpcrdma_create_id(r_xprt, ia);
+	if (IS_ERR(id))
+		goto out;
+
+	/* As long as the new ID points to the same device as the
+	 * old ID, we can reuse the transport's existing PD and all
+	 * previously allocated MRs. Also, the same device means
+	 * the transport's previous DMA mappings are still valid.
+	 *
+	 * This is a sanity check only. There should be no way these
+	 * point to two different devices here.
+	 */
+	old = id;
+	rc = -ENETUNREACH;
+	if (ia->ri_device != id->device) {
+		pr_err("rpcrdma: can't reconnect on different device!\n");
+		goto out_destroy;
+	}
+
+	err = rdma_create_qp(id, ia->ri_pd, &ep->rep_attr);
+	if (err) {
+		dprintk("RPC:       %s: rdma_create_qp returned %d\n",
+			__func__, err);
+		goto out_destroy;
+	}
+
+	/* Atomically replace the transport's ID and QP. */
+	rc = 0;
+	old = ia->ri_id;
+	ia->ri_id = id;
+	rdma_destroy_qp(old);
+
+out_destroy:
+	rdma_destroy_id(old);
+out:
+	return rc;
+}
+
+/*
+ * Connect unconnected endpoint.
+ */
+int
+rpcrdma_ep_connect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
+{
+	struct rpcrdma_xprt *r_xprt = container_of(ia, struct rpcrdma_xprt,
+						   rx_ia);
+	int rc;
+
+retry:
+	switch (ep->rep_connected) {
+	case 0:
+		dprintk("RPC:       %s: connecting...\n", __func__);
+		rc = rdma_create_qp(ia->ri_id, ia->ri_pd, &ep->rep_attr);
+		if (rc) {
+			dprintk("RPC:       %s: rdma_create_qp failed %i\n",
+				__func__, rc);
+			rc = -ENETUNREACH;
+			goto out_noupdate;
+		}
+		break;
+	case -ENODEV:
+		rc = rpcrdma_ep_recreate_xprt(r_xprt, ep, ia);
+		if (rc)
+			goto out_noupdate;
+		break;
+	default:
+		rc = rpcrdma_ep_reconnect(r_xprt, ep, ia);
+		if (rc)
+			goto out;
+	}
+
+	ep->rep_connected = 0;
+	rpcrdma_post_recvs(r_xprt, true);
+
+	rc = rdma_connect(ia->ri_id, &ep->rep_remote_cma);
+	if (rc) {
+		dprintk("RPC:       %s: rdma_connect() failed with %i\n",
+				__func__, rc);
+		goto out;
+	}
+
+	wait_event_interruptible(ep->rep_connect_wait, ep->rep_connected != 0);
+	if (ep->rep_connected <= 0) {
+		if (ep->rep_connected == -EAGAIN)
+			goto retry;
+		rc = ep->rep_connected;
+		goto out;
+	}
+
+	dprintk("RPC:       %s: connected\n", __func__);
+
+out:
+	if (rc)
+		ep->rep_connected = rc;
+
+out_noupdate:
+	return rc;
+}
+
+/*
+ * rpcrdma_ep_disconnect
+ *
+ * This is separate from destroy to facilitate the ability
+ * to reconnect without recreating the endpoint.
+ *
+ * This call is not reentrant, and must not be made in parallel
+ * on the same endpoint.
+ */
+void
+rpcrdma_ep_disconnect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
+{
+	int rc;
+
+	rc = rdma_disconnect(ia->ri_id);
+	if (!rc)
+		/* returns without wait if not connected */
+		wait_event_interruptible(ep->rep_connect_wait,
+							ep->rep_connected != 1);
+	else
+		ep->rep_connected = rc;
+	trace_xprtrdma_disconnect(container_of(ep, struct rpcrdma_xprt,
+					       rx_ep), rc);
+
+	ib_drain_qp(ia->ri_id->qp);
+}
+
+/* Fixed-size circular FIFO queue. This implementation is wait-free and
+ * lock-free.
+ *
+ * Consumer is the code path that posts Sends. This path dequeues a
+ * sendctx for use by a Send operation. Multiple consumer threads
+ * are serialized by the RPC transport lock, which allows only one
+ * ->send_request call at a time.
+ *
+ * Producer is the code path that handles Send completions. This path
+ * enqueues a sendctx that has been completed. Multiple producer
+ * threads are serialized by the ib_poll_cq() function.
+ */
+
+/* rpcrdma_sendctxs_destroy() assumes caller has already quiesced
+ * queue activity, and ib_drain_qp has flushed all remaining Send
+ * requests.
+ */
+static void rpcrdma_sendctxs_destroy(struct rpcrdma_buffer *buf)
+{
+	unsigned long i;
+
+	for (i = 0; i <= buf->rb_sc_last; i++)
+		kfree(buf->rb_sc_ctxs[i]);
+	kfree(buf->rb_sc_ctxs);
+}
+
+static struct rpcrdma_sendctx *rpcrdma_sendctx_create(struct rpcrdma_ia *ia)
+{
+	struct rpcrdma_sendctx *sc;
+
+	sc = kzalloc(sizeof(*sc) +
+		     ia->ri_max_send_sges * sizeof(struct ib_sge),
+		     GFP_KERNEL);
+	if (!sc)
+		return NULL;
+
+	sc->sc_wr.wr_cqe = &sc->sc_cqe;
+	sc->sc_wr.sg_list = sc->sc_sges;
+	sc->sc_wr.opcode = IB_WR_SEND;
+	sc->sc_cqe.done = rpcrdma_wc_send;
+	return sc;
+}
+
+static int rpcrdma_sendctxs_create(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_sendctx *sc;
+	unsigned long i;
+
+	/* Maximum number of concurrent outstanding Send WRs. Capping
+	 * the circular queue size stops Send Queue overflow by causing
+	 * the ->send_request call to fail temporarily before too many
+	 * Sends are posted.
+	 */
+	i = buf->rb_max_requests + RPCRDMA_MAX_BC_REQUESTS;
+	dprintk("RPC:       %s: allocating %lu send_ctxs\n", __func__, i);
+	buf->rb_sc_ctxs = kcalloc(i, sizeof(sc), GFP_KERNEL);
+	if (!buf->rb_sc_ctxs)
+		return -ENOMEM;
+
+	buf->rb_sc_last = i - 1;
+	for (i = 0; i <= buf->rb_sc_last; i++) {
+		sc = rpcrdma_sendctx_create(&r_xprt->rx_ia);
+		if (!sc)
+			return -ENOMEM;
+
+		sc->sc_xprt = r_xprt;
+		buf->rb_sc_ctxs[i] = sc;
+	}
+	buf->rb_flags = 0;
+
+	return 0;
+}
+
+/* The sendctx queue is not guaranteed to have a size that is a
+ * power of two, thus the helpers in circ_buf.h cannot be used.
+ * The other option is to use modulus (%), which can be expensive.
+ */
+static unsigned long rpcrdma_sendctx_next(struct rpcrdma_buffer *buf,
+					  unsigned long item)
+{
+	return likely(item < buf->rb_sc_last) ? item + 1 : 0;
+}
+
+/**
+ * rpcrdma_sendctx_get_locked - Acquire a send context
+ * @buf: transport buffers from which to acquire an unused context
+ *
+ * Returns pointer to a free send completion context; or NULL if
+ * the queue is empty.
+ *
+ * Usage: Called to acquire an SGE array before preparing a Send WR.
+ *
+ * The caller serializes calls to this function (per rpcrdma_buffer),
+ * and provides an effective memory barrier that flushes the new value
+ * of rb_sc_head.
+ */
+struct rpcrdma_sendctx *rpcrdma_sendctx_get_locked(struct rpcrdma_buffer *buf)
+{
+	struct rpcrdma_xprt *r_xprt;
+	struct rpcrdma_sendctx *sc;
+	unsigned long next_head;
+
+	next_head = rpcrdma_sendctx_next(buf, buf->rb_sc_head);
+
+	if (next_head == READ_ONCE(buf->rb_sc_tail))
+		goto out_emptyq;
+
+	/* ORDER: item must be accessed _before_ head is updated */
+	sc = buf->rb_sc_ctxs[next_head];
+
+	/* Releasing the lock in the caller acts as a memory
+	 * barrier that flushes rb_sc_head.
+	 */
+	buf->rb_sc_head = next_head;
+
+	return sc;
+
+out_emptyq:
+	/* The queue is "empty" if there have not been enough Send
+	 * completions recently. This is a sign the Send Queue is
+	 * backing up. Cause the caller to pause and try again.
+	 */
+	set_bit(RPCRDMA_BUF_F_EMPTY_SCQ, &buf->rb_flags);
+	r_xprt = container_of(buf, struct rpcrdma_xprt, rx_buf);
+	r_xprt->rx_stats.empty_sendctx_q++;
+	return NULL;
+}
+
+/**
+ * rpcrdma_sendctx_put_locked - Release a send context
+ * @sc: send context to release
+ *
+ * Usage: Called from Send completion to return a sendctxt
+ * to the queue.
+ *
+ * The caller serializes calls to this function (per rpcrdma_buffer).
+ */
+static void
+rpcrdma_sendctx_put_locked(struct rpcrdma_sendctx *sc)
+{
+	struct rpcrdma_buffer *buf = &sc->sc_xprt->rx_buf;
+	unsigned long next_tail;
+
+	/* Unmap SGEs of previously completed by unsignaled
+	 * Sends by walking up the queue until @sc is found.
+	 */
+	next_tail = buf->rb_sc_tail;
+	do {
+		next_tail = rpcrdma_sendctx_next(buf, next_tail);
+
+		/* ORDER: item must be accessed _before_ tail is updated */
+		rpcrdma_unmap_sendctx(buf->rb_sc_ctxs[next_tail]);
+
+	} while (buf->rb_sc_ctxs[next_tail] != sc);
+
+	/* Paired with READ_ONCE */
+	smp_store_release(&buf->rb_sc_tail, next_tail);
+
+	if (test_and_clear_bit(RPCRDMA_BUF_F_EMPTY_SCQ, &buf->rb_flags)) {
+		smp_mb__after_atomic();
+		xprt_write_space(&sc->sc_xprt->rx_xprt);
+	}
+}
+
+static void
+rpcrdma_mr_recovery_worker(struct work_struct *work)
+{
+	struct rpcrdma_buffer *buf = container_of(work, struct rpcrdma_buffer,
+						  rb_recovery_worker.work);
+	struct rpcrdma_mr *mr;
+
+	spin_lock(&buf->rb_recovery_lock);
+	while (!list_empty(&buf->rb_stale_mrs)) {
+		mr = rpcrdma_mr_pop(&buf->rb_stale_mrs);
+		spin_unlock(&buf->rb_recovery_lock);
+
+		trace_xprtrdma_recover_mr(mr);
+		mr->mr_xprt->rx_ia.ri_ops->ro_recover_mr(mr);
+
+		spin_lock(&buf->rb_recovery_lock);
+	}
+	spin_unlock(&buf->rb_recovery_lock);
+}
+
+void
+rpcrdma_mr_defer_recovery(struct rpcrdma_mr *mr)
+{
+	struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+
+	spin_lock(&buf->rb_recovery_lock);
+	rpcrdma_mr_push(mr, &buf->rb_stale_mrs);
+	spin_unlock(&buf->rb_recovery_lock);
+
+	schedule_delayed_work(&buf->rb_recovery_worker, 0);
+}
+
+static void
+rpcrdma_mrs_create(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
+	unsigned int count;
+	LIST_HEAD(free);
+	LIST_HEAD(all);
+
+	for (count = 0; count < 3; count++) {
+		struct rpcrdma_mr *mr;
+		int rc;
+
+		mr = kzalloc(sizeof(*mr), GFP_KERNEL);
+		if (!mr)
+			break;
+
+		rc = ia->ri_ops->ro_init_mr(ia, mr);
+		if (rc) {
+			kfree(mr);
+			break;
+		}
+
+		mr->mr_xprt = r_xprt;
+
+		list_add(&mr->mr_list, &free);
+		list_add(&mr->mr_all, &all);
+	}
+
+	spin_lock(&buf->rb_mrlock);
+	list_splice(&free, &buf->rb_mrs);
+	list_splice(&all, &buf->rb_all);
+	r_xprt->rx_stats.mrs_allocated += count;
+	spin_unlock(&buf->rb_mrlock);
+	trace_xprtrdma_createmrs(r_xprt, count);
+
+	xprt_write_space(&r_xprt->rx_xprt);
+}
+
+static void
+rpcrdma_mr_refresh_worker(struct work_struct *work)
+{
+	struct rpcrdma_buffer *buf = container_of(work, struct rpcrdma_buffer,
+						  rb_refresh_worker.work);
+	struct rpcrdma_xprt *r_xprt = container_of(buf, struct rpcrdma_xprt,
+						   rx_buf);
+
+	rpcrdma_mrs_create(r_xprt);
+}
+
+struct rpcrdma_req *
+rpcrdma_create_req(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buffer = &r_xprt->rx_buf;
+	struct rpcrdma_regbuf *rb;
+	struct rpcrdma_req *req;
+
+	req = kzalloc(sizeof(*req), GFP_KERNEL);
+	if (req == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	rb = rpcrdma_alloc_regbuf(RPCRDMA_HDRBUF_SIZE,
+				  DMA_TO_DEVICE, GFP_KERNEL);
+	if (IS_ERR(rb)) {
+		kfree(req);
+		return ERR_PTR(-ENOMEM);
+	}
+	req->rl_rdmabuf = rb;
+	xdr_buf_init(&req->rl_hdrbuf, rb->rg_base, rdmab_length(rb));
+	req->rl_buffer = buffer;
+	INIT_LIST_HEAD(&req->rl_registered);
+
+	spin_lock(&buffer->rb_reqslock);
+	list_add(&req->rl_all, &buffer->rb_allreqs);
+	spin_unlock(&buffer->rb_reqslock);
+	return req;
+}
+
+static int
+rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt, bool temp)
+{
+	struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_rep *rep;
+	int rc;
+
+	rc = -ENOMEM;
+	rep = kzalloc(sizeof(*rep), GFP_KERNEL);
+	if (rep == NULL)
+		goto out;
+
+	rep->rr_rdmabuf = rpcrdma_alloc_regbuf(cdata->inline_rsize,
+					       DMA_FROM_DEVICE, GFP_KERNEL);
+	if (IS_ERR(rep->rr_rdmabuf)) {
+		rc = PTR_ERR(rep->rr_rdmabuf);
+		goto out_free;
+	}
+	xdr_buf_init(&rep->rr_hdrbuf, rep->rr_rdmabuf->rg_base,
+		     rdmab_length(rep->rr_rdmabuf));
+
+	rep->rr_cqe.done = rpcrdma_wc_receive;
+	rep->rr_rxprt = r_xprt;
+	INIT_WORK(&rep->rr_work, rpcrdma_deferred_completion);
+	rep->rr_recv_wr.next = NULL;
+	rep->rr_recv_wr.wr_cqe = &rep->rr_cqe;
+	rep->rr_recv_wr.sg_list = &rep->rr_rdmabuf->rg_iov;
+	rep->rr_recv_wr.num_sge = 1;
+	rep->rr_temp = temp;
+
+	spin_lock(&buf->rb_lock);
+	list_add(&rep->rr_list, &buf->rb_recv_bufs);
+	spin_unlock(&buf->rb_lock);
+	return 0;
+
+out_free:
+	kfree(rep);
+out:
+	dprintk("RPC:       %s: reply buffer %d alloc failed\n",
+		__func__, rc);
+	return rc;
+}
+
+int
+rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	int i, rc;
+
+	buf->rb_max_requests = r_xprt->rx_data.max_requests;
+	buf->rb_bc_srv_max_requests = 0;
+	spin_lock_init(&buf->rb_mrlock);
+	spin_lock_init(&buf->rb_lock);
+	spin_lock_init(&buf->rb_recovery_lock);
+	INIT_LIST_HEAD(&buf->rb_mrs);
+	INIT_LIST_HEAD(&buf->rb_all);
+	INIT_LIST_HEAD(&buf->rb_stale_mrs);
+	INIT_DELAYED_WORK(&buf->rb_refresh_worker,
+			  rpcrdma_mr_refresh_worker);
+	INIT_DELAYED_WORK(&buf->rb_recovery_worker,
+			  rpcrdma_mr_recovery_worker);
+
+	rpcrdma_mrs_create(r_xprt);
+
+	INIT_LIST_HEAD(&buf->rb_send_bufs);
+	INIT_LIST_HEAD(&buf->rb_allreqs);
+	spin_lock_init(&buf->rb_reqslock);
+	for (i = 0; i < buf->rb_max_requests; i++) {
+		struct rpcrdma_req *req;
+
+		req = rpcrdma_create_req(r_xprt);
+		if (IS_ERR(req)) {
+			dprintk("RPC:       %s: request buffer %d alloc"
+				" failed\n", __func__, i);
+			rc = PTR_ERR(req);
+			goto out;
+		}
+		list_add(&req->rl_list, &buf->rb_send_bufs);
+	}
+
+	buf->rb_credits = 1;
+	buf->rb_posted_receives = 0;
+	INIT_LIST_HEAD(&buf->rb_recv_bufs);
+
+	rc = rpcrdma_sendctxs_create(r_xprt);
+	if (rc)
+		goto out;
+
+	return 0;
+out:
+	rpcrdma_buffer_destroy(buf);
+	return rc;
+}
+
+static void
+rpcrdma_destroy_rep(struct rpcrdma_rep *rep)
+{
+	rpcrdma_free_regbuf(rep->rr_rdmabuf);
+	kfree(rep);
+}
+
+void
+rpcrdma_destroy_req(struct rpcrdma_req *req)
+{
+	rpcrdma_free_regbuf(req->rl_recvbuf);
+	rpcrdma_free_regbuf(req->rl_sendbuf);
+	rpcrdma_free_regbuf(req->rl_rdmabuf);
+	kfree(req);
+}
+
+static void
+rpcrdma_mrs_destroy(struct rpcrdma_buffer *buf)
+{
+	struct rpcrdma_xprt *r_xprt = container_of(buf, struct rpcrdma_xprt,
+						   rx_buf);
+	struct rpcrdma_ia *ia = rdmab_to_ia(buf);
+	struct rpcrdma_mr *mr;
+	unsigned int count;
+
+	count = 0;
+	spin_lock(&buf->rb_mrlock);
+	while (!list_empty(&buf->rb_all)) {
+		mr = list_entry(buf->rb_all.next, struct rpcrdma_mr, mr_all);
+		list_del(&mr->mr_all);
+
+		spin_unlock(&buf->rb_mrlock);
+
+		/* Ensure MW is not on any rl_registered list */
+		if (!list_empty(&mr->mr_list))
+			list_del(&mr->mr_list);
+
+		ia->ri_ops->ro_release_mr(mr);
+		count++;
+		spin_lock(&buf->rb_mrlock);
+	}
+	spin_unlock(&buf->rb_mrlock);
+	r_xprt->rx_stats.mrs_allocated = 0;
+
+	dprintk("RPC:       %s: released %u MRs\n", __func__, count);
+}
+
+void
+rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf)
+{
+	cancel_delayed_work_sync(&buf->rb_recovery_worker);
+	cancel_delayed_work_sync(&buf->rb_refresh_worker);
+
+	rpcrdma_sendctxs_destroy(buf);
+
+	while (!list_empty(&buf->rb_recv_bufs)) {
+		struct rpcrdma_rep *rep;
+
+		rep = list_first_entry(&buf->rb_recv_bufs,
+				       struct rpcrdma_rep, rr_list);
+		list_del(&rep->rr_list);
+		rpcrdma_destroy_rep(rep);
+	}
+
+	spin_lock(&buf->rb_reqslock);
+	while (!list_empty(&buf->rb_allreqs)) {
+		struct rpcrdma_req *req;
+
+		req = list_first_entry(&buf->rb_allreqs,
+				       struct rpcrdma_req, rl_all);
+		list_del(&req->rl_all);
+
+		spin_unlock(&buf->rb_reqslock);
+		rpcrdma_destroy_req(req);
+		spin_lock(&buf->rb_reqslock);
+	}
+	spin_unlock(&buf->rb_reqslock);
+
+	rpcrdma_mrs_destroy(buf);
+}
+
+/**
+ * rpcrdma_mr_get - Allocate an rpcrdma_mr object
+ * @r_xprt: controlling transport
+ *
+ * Returns an initialized rpcrdma_mr or NULL if no free
+ * rpcrdma_mr objects are available.
+ */
+struct rpcrdma_mr *
+rpcrdma_mr_get(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_mr *mr = NULL;
+
+	spin_lock(&buf->rb_mrlock);
+	if (!list_empty(&buf->rb_mrs))
+		mr = rpcrdma_mr_pop(&buf->rb_mrs);
+	spin_unlock(&buf->rb_mrlock);
+
+	if (!mr)
+		goto out_nomrs;
+	return mr;
+
+out_nomrs:
+	trace_xprtrdma_nomrs(r_xprt);
+	if (r_xprt->rx_ep.rep_connected != -ENODEV)
+		schedule_delayed_work(&buf->rb_refresh_worker, 0);
+
+	/* Allow the reply handler and refresh worker to run */
+	cond_resched();
+
+	return NULL;
+}
+
+static void
+__rpcrdma_mr_put(struct rpcrdma_buffer *buf, struct rpcrdma_mr *mr)
+{
+	spin_lock(&buf->rb_mrlock);
+	rpcrdma_mr_push(mr, &buf->rb_mrs);
+	spin_unlock(&buf->rb_mrlock);
+}
+
+/**
+ * rpcrdma_mr_put - Release an rpcrdma_mr object
+ * @mr: object to release
+ *
+ */
+void
+rpcrdma_mr_put(struct rpcrdma_mr *mr)
+{
+	__rpcrdma_mr_put(&mr->mr_xprt->rx_buf, mr);
+}
+
+/**
+ * rpcrdma_mr_unmap_and_put - DMA unmap an MR and release it
+ * @mr: object to release
+ *
+ */
+void
+rpcrdma_mr_unmap_and_put(struct rpcrdma_mr *mr)
+{
+	struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
+
+	trace_xprtrdma_dma_unmap(mr);
+	ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
+			mr->mr_sg, mr->mr_nents, mr->mr_dir);
+	__rpcrdma_mr_put(&r_xprt->rx_buf, mr);
+}
+
+/**
+ * rpcrdma_buffer_get - Get a request buffer
+ * @buffers: Buffer pool from which to obtain a buffer
+ *
+ * Returns a fresh rpcrdma_req, or NULL if none are available.
+ */
+struct rpcrdma_req *
+rpcrdma_buffer_get(struct rpcrdma_buffer *buffers)
+{
+	struct rpcrdma_req *req;
+
+	spin_lock(&buffers->rb_lock);
+	req = list_first_entry_or_null(&buffers->rb_send_bufs,
+				       struct rpcrdma_req, rl_list);
+	if (req)
+		list_del_init(&req->rl_list);
+	spin_unlock(&buffers->rb_lock);
+	return req;
+}
+
+/**
+ * rpcrdma_buffer_put - Put request/reply buffers back into pool
+ * @req: object to return
+ *
+ */
+void
+rpcrdma_buffer_put(struct rpcrdma_req *req)
+{
+	struct rpcrdma_buffer *buffers = req->rl_buffer;
+	struct rpcrdma_rep *rep = req->rl_reply;
+
+	req->rl_reply = NULL;
+
+	spin_lock(&buffers->rb_lock);
+	list_add(&req->rl_list, &buffers->rb_send_bufs);
+	if (rep) {
+		if (!rep->rr_temp) {
+			list_add(&rep->rr_list, &buffers->rb_recv_bufs);
+			rep = NULL;
+		}
+	}
+	spin_unlock(&buffers->rb_lock);
+	if (rep)
+		rpcrdma_destroy_rep(rep);
+}
+
+/*
+ * Put reply buffers back into pool when not attached to
+ * request. This happens in error conditions.
+ */
+void
+rpcrdma_recv_buffer_put(struct rpcrdma_rep *rep)
+{
+	struct rpcrdma_buffer *buffers = &rep->rr_rxprt->rx_buf;
+
+	if (!rep->rr_temp) {
+		spin_lock(&buffers->rb_lock);
+		list_add(&rep->rr_list, &buffers->rb_recv_bufs);
+		spin_unlock(&buffers->rb_lock);
+	} else {
+		rpcrdma_destroy_rep(rep);
+	}
+}
+
+/**
+ * rpcrdma_alloc_regbuf - allocate and DMA-map memory for SEND/RECV buffers
+ * @size: size of buffer to be allocated, in bytes
+ * @direction: direction of data movement
+ * @flags: GFP flags
+ *
+ * Returns an ERR_PTR, or a pointer to a regbuf, a buffer that
+ * can be persistently DMA-mapped for I/O.
+ *
+ * xprtrdma uses a regbuf for posting an outgoing RDMA SEND, or for
+ * receiving the payload of RDMA RECV operations. During Long Calls
+ * or Replies they may be registered externally via ro_map.
+ */
+struct rpcrdma_regbuf *
+rpcrdma_alloc_regbuf(size_t size, enum dma_data_direction direction,
+		     gfp_t flags)
+{
+	struct rpcrdma_regbuf *rb;
+
+	rb = kmalloc(sizeof(*rb) + size, flags);
+	if (rb == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	rb->rg_device = NULL;
+	rb->rg_direction = direction;
+	rb->rg_iov.length = size;
+
+	return rb;
+}
+
+/**
+ * __rpcrdma_map_regbuf - DMA-map a regbuf
+ * @ia: controlling rpcrdma_ia
+ * @rb: regbuf to be mapped
+ */
+bool
+__rpcrdma_dma_map_regbuf(struct rpcrdma_ia *ia, struct rpcrdma_regbuf *rb)
+{
+	struct ib_device *device = ia->ri_device;
+
+	if (rb->rg_direction == DMA_NONE)
+		return false;
+
+	rb->rg_iov.addr = ib_dma_map_single(device,
+					    (void *)rb->rg_base,
+					    rdmab_length(rb),
+					    rb->rg_direction);
+	if (ib_dma_mapping_error(device, rdmab_addr(rb)))
+		return false;
+
+	rb->rg_device = device;
+	rb->rg_iov.lkey = ia->ri_pd->local_dma_lkey;
+	return true;
+}
+
+static void
+rpcrdma_dma_unmap_regbuf(struct rpcrdma_regbuf *rb)
+{
+	if (!rb)
+		return;
+
+	if (!rpcrdma_regbuf_is_mapped(rb))
+		return;
+
+	ib_dma_unmap_single(rb->rg_device, rdmab_addr(rb),
+			    rdmab_length(rb), rb->rg_direction);
+	rb->rg_device = NULL;
+}
+
+/**
+ * rpcrdma_free_regbuf - deregister and free registered buffer
+ * @rb: regbuf to be deregistered and freed
+ */
+void
+rpcrdma_free_regbuf(struct rpcrdma_regbuf *rb)
+{
+	rpcrdma_dma_unmap_regbuf(rb);
+	kfree(rb);
+}
+
+/*
+ * Prepost any receive buffer, then post send.
+ *
+ * Receive buffer is donated to hardware, reclaimed upon recv completion.
+ */
+int
+rpcrdma_ep_post(struct rpcrdma_ia *ia,
+		struct rpcrdma_ep *ep,
+		struct rpcrdma_req *req)
+{
+	struct ib_send_wr *send_wr = &req->rl_sendctx->sc_wr;
+	int rc;
+
+	if (!ep->rep_send_count ||
+	    test_bit(RPCRDMA_REQ_F_TX_RESOURCES, &req->rl_flags)) {
+		send_wr->send_flags |= IB_SEND_SIGNALED;
+		ep->rep_send_count = ep->rep_send_batch;
+	} else {
+		send_wr->send_flags &= ~IB_SEND_SIGNALED;
+		--ep->rep_send_count;
+	}
+
+	rc = ia->ri_ops->ro_send(ia, req);
+	trace_xprtrdma_post_send(req, rc);
+	if (rc)
+		return -ENOTCONN;
+	return 0;
+}
+
+/**
+ * rpcrdma_post_recvs - Maybe post some Receive buffers
+ * @r_xprt: controlling transport
+ * @temp: when true, allocate temp rpcrdma_rep objects
+ *
+ */
+void
+rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, bool temp)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct ib_recv_wr *wr, *bad_wr;
+	int needed, count, rc;
+
+	needed = buf->rb_credits + (buf->rb_bc_srv_max_requests << 1);
+	if (buf->rb_posted_receives > needed)
+		return;
+	needed -= buf->rb_posted_receives;
+
+	count = 0;
+	wr = NULL;
+	while (needed) {
+		struct rpcrdma_regbuf *rb;
+		struct rpcrdma_rep *rep;
+
+		spin_lock(&buf->rb_lock);
+		rep = list_first_entry_or_null(&buf->rb_recv_bufs,
+					       struct rpcrdma_rep, rr_list);
+		if (likely(rep))
+			list_del(&rep->rr_list);
+		spin_unlock(&buf->rb_lock);
+		if (!rep) {
+			if (rpcrdma_create_rep(r_xprt, temp))
+				break;
+			continue;
+		}
+
+		rb = rep->rr_rdmabuf;
+		if (!rpcrdma_regbuf_is_mapped(rb)) {
+			if (!__rpcrdma_dma_map_regbuf(&r_xprt->rx_ia, rb)) {
+				rpcrdma_recv_buffer_put(rep);
+				break;
+			}
+		}
+
+		trace_xprtrdma_post_recv(rep->rr_recv_wr.wr_cqe);
+		rep->rr_recv_wr.next = wr;
+		wr = &rep->rr_recv_wr;
+		++count;
+		--needed;
+	}
+	if (!count)
+		return;
+
+	rc = ib_post_recv(r_xprt->rx_ia.ri_id->qp, wr,
+			  (const struct ib_recv_wr **)&bad_wr);
+	if (rc) {
+		for (wr = bad_wr; wr;) {
+			struct rpcrdma_rep *rep;
+
+			rep = container_of(wr, struct rpcrdma_rep, rr_recv_wr);
+			wr = wr->next;
+			rpcrdma_recv_buffer_put(rep);
+			--count;
+		}
+	}
+	buf->rb_posted_receives += count;
+	trace_xprtrdma_post_recvs(r_xprt, count, rc);
+}