Adding upstream version 6.1.76.upstream/6.1.76upstream

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

1 files changed, 1396 insertions, 0 deletions

diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
new file mode 100644
index 000000000..28c0771c4
--- /dev/null
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -0,0 +1,1396 @@
+// 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 <linux/log2.h>
+
+#include <asm-generic/barrier.h>
+#include <asm/bitops.h>
+
+#include <rdma/ib_cm.h>
+
+#include "xprt_rdma.h"
+#include <trace/events/rpcrdma.h>
+
+static int rpcrdma_sendctxs_create(struct rpcrdma_xprt *r_xprt);
+static void rpcrdma_sendctxs_destroy(struct rpcrdma_xprt *r_xprt);
+static void rpcrdma_sendctx_put_locked(struct rpcrdma_xprt *r_xprt,
+				       struct rpcrdma_sendctx *sc);
+static int rpcrdma_reqs_setup(struct rpcrdma_xprt *r_xprt);
+static void rpcrdma_reqs_reset(struct rpcrdma_xprt *r_xprt);
+static void rpcrdma_rep_destroy(struct rpcrdma_rep *rep);
+static void rpcrdma_reps_unmap(struct rpcrdma_xprt *r_xprt);
+static void rpcrdma_mrs_create(struct rpcrdma_xprt *r_xprt);
+static void rpcrdma_mrs_destroy(struct rpcrdma_xprt *r_xprt);
+static void rpcrdma_ep_get(struct rpcrdma_ep *ep);
+static int rpcrdma_ep_put(struct rpcrdma_ep *ep);
+static struct rpcrdma_regbuf *
+rpcrdma_regbuf_alloc(size_t size, enum dma_data_direction direction);
+static void rpcrdma_regbuf_dma_unmap(struct rpcrdma_regbuf *rb);
+static void rpcrdma_regbuf_free(struct rpcrdma_regbuf *rb);
+
+/* Wait for outstanding transport work to finish. ib_drain_qp
+ * handles the drains in the wrong order for us, so open code
+ * them here.
+ */
+static void rpcrdma_xprt_drain(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_ep *ep = r_xprt->rx_ep;
+	struct rdma_cm_id *id = ep->re_id;
+
+	/* Wait for rpcrdma_post_recvs() to leave its critical
+	 * section.
+	 */
+	if (atomic_inc_return(&ep->re_receiving) > 1)
+		wait_for_completion(&ep->re_done);
+
+	/* Flush Receives, then wait for deferred Reply work
+	 * to complete.
+	 */
+	ib_drain_rq(id->qp);
+
+	/* Deferred Reply processing might have scheduled
+	 * local invalidations.
+	 */
+	ib_drain_sq(id->qp);
+
+	rpcrdma_ep_put(ep);
+}
+
+/* Ensure xprt_force_disconnect() is invoked exactly once when a
+ * connection is closed or lost. (The important thing is it needs
+ * to be invoked "at least" once).
+ */
+void rpcrdma_force_disconnect(struct rpcrdma_ep *ep)
+{
+	if (atomic_add_unless(&ep->re_force_disconnect, 1, 1))
+		xprt_force_disconnect(ep->re_xprt);
+}
+
+/**
+ * rpcrdma_flush_disconnect - Disconnect on flushed completion
+ * @r_xprt: transport to disconnect
+ * @wc: work completion entry
+ *
+ * Must be called in process context.
+ */
+void rpcrdma_flush_disconnect(struct rpcrdma_xprt *r_xprt, struct ib_wc *wc)
+{
+	if (wc->status != IB_WC_SUCCESS)
+		rpcrdma_force_disconnect(r_xprt->rx_ep);
+}
+
+/**
+ * rpcrdma_wc_send - Invoked by RDMA provider for each polled Send WC
+ * @cq:	completion queue
+ * @wc:	WCE for a completed Send 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);
+	struct rpcrdma_xprt *r_xprt = cq->cq_context;
+
+	/* WARNING: Only wr_cqe and status are reliable at this point */
+	trace_xprtrdma_wc_send(wc, &sc->sc_cid);
+	rpcrdma_sendctx_put_locked(r_xprt, sc);
+	rpcrdma_flush_disconnect(r_xprt, wc);
+}
+
+/**
+ * rpcrdma_wc_receive - Invoked by RDMA provider for each polled Receive WC
+ * @cq:	completion queue
+ * @wc:	WCE for a completed Receive 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);
+	struct rpcrdma_xprt *r_xprt = cq->cq_context;
+
+	/* WARNING: Only wr_cqe and status are reliable at this point */
+	trace_xprtrdma_wc_receive(wc, &rep->rr_cid);
+	--r_xprt->rx_ep->re_receive_count;
+	if (wc->status != IB_WC_SUCCESS)
+		goto out_flushed;
+
+	/* 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);
+
+	rpcrdma_reply_handler(rep);
+	return;
+
+out_flushed:
+	rpcrdma_flush_disconnect(r_xprt, wc);
+	rpcrdma_rep_put(&r_xprt->rx_buf, rep);
+}
+
+static void rpcrdma_update_cm_private(struct rpcrdma_ep *ep,
+				      struct rdma_conn_param *param)
+{
+	const struct rpcrdma_connect_private *pmsg = param->private_data;
+	unsigned int rsize, wsize;
+
+	/* Default settings for RPC-over-RDMA Version One */
+	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) {
+		rsize = rpcrdma_decode_buffer_size(pmsg->cp_send_size);
+		wsize = rpcrdma_decode_buffer_size(pmsg->cp_recv_size);
+	}
+
+	if (rsize < ep->re_inline_recv)
+		ep->re_inline_recv = rsize;
+	if (wsize < ep->re_inline_send)
+		ep->re_inline_send = wsize;
+
+	rpcrdma_set_max_header_sizes(ep);
+}
+
+/**
+ * rpcrdma_cm_event_handler - Handle RDMA CM events
+ * @id: rdma_cm_id on which an event has occurred
+ * @event: details of the event
+ *
+ * Called with @id's mutex held. Returns 1 if caller should
+ * destroy @id, otherwise 0.
+ */
+static int
+rpcrdma_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event)
+{
+	struct sockaddr *sap = (struct sockaddr *)&id->route.addr.dst_addr;
+	struct rpcrdma_ep *ep = id->context;
+
+	might_sleep();
+
+	switch (event->event) {
+	case RDMA_CM_EVENT_ADDR_RESOLVED:
+	case RDMA_CM_EVENT_ROUTE_RESOLVED:
+		ep->re_async_rc = 0;
+		complete(&ep->re_done);
+		return 0;
+	case RDMA_CM_EVENT_ADDR_ERROR:
+		ep->re_async_rc = -EPROTO;
+		complete(&ep->re_done);
+		return 0;
+	case RDMA_CM_EVENT_ROUTE_ERROR:
+		ep->re_async_rc = -ENETUNREACH;
+		complete(&ep->re_done);
+		return 0;
+	case RDMA_CM_EVENT_DEVICE_REMOVAL:
+		pr_info("rpcrdma: removing device %s for %pISpc\n",
+			ep->re_id->device->name, sap);
+		fallthrough;
+	case RDMA_CM_EVENT_ADDR_CHANGE:
+		ep->re_connect_status = -ENODEV;
+		goto disconnected;
+	case RDMA_CM_EVENT_ESTABLISHED:
+		rpcrdma_ep_get(ep);
+		ep->re_connect_status = 1;
+		rpcrdma_update_cm_private(ep, &event->param.conn);
+		trace_xprtrdma_inline_thresh(ep);
+		wake_up_all(&ep->re_connect_wait);
+		break;
+	case RDMA_CM_EVENT_CONNECT_ERROR:
+		ep->re_connect_status = -ENOTCONN;
+		goto wake_connect_worker;
+	case RDMA_CM_EVENT_UNREACHABLE:
+		ep->re_connect_status = -ENETUNREACH;
+		goto wake_connect_worker;
+	case RDMA_CM_EVENT_REJECTED:
+		ep->re_connect_status = -ECONNREFUSED;
+		if (event->status == IB_CM_REJ_STALE_CONN)
+			ep->re_connect_status = -ENOTCONN;
+wake_connect_worker:
+		wake_up_all(&ep->re_connect_wait);
+		return 0;
+	case RDMA_CM_EVENT_DISCONNECTED:
+		ep->re_connect_status = -ECONNABORTED;
+disconnected:
+		rpcrdma_force_disconnect(ep);
+		return rpcrdma_ep_put(ep);
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static struct rdma_cm_id *rpcrdma_create_id(struct rpcrdma_xprt *r_xprt,
+					    struct rpcrdma_ep *ep)
+{
+	unsigned long wtimeout = msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT) + 1;
+	struct rpc_xprt *xprt = &r_xprt->rx_xprt;
+	struct rdma_cm_id *id;
+	int rc;
+
+	init_completion(&ep->re_done);
+
+	id = rdma_create_id(xprt->xprt_net, rpcrdma_cm_event_handler, ep,
+			    RDMA_PS_TCP, IB_QPT_RC);
+	if (IS_ERR(id))
+		return id;
+
+	ep->re_async_rc = -ETIMEDOUT;
+	rc = rdma_resolve_addr(id, NULL, (struct sockaddr *)&xprt->addr,
+			       RDMA_RESOLVE_TIMEOUT);
+	if (rc)
+		goto out;
+	rc = wait_for_completion_interruptible_timeout(&ep->re_done, wtimeout);
+	if (rc < 0)
+		goto out;
+
+	rc = ep->re_async_rc;
+	if (rc)
+		goto out;
+
+	ep->re_async_rc = -ETIMEDOUT;
+	rc = rdma_resolve_route(id, RDMA_RESOLVE_TIMEOUT);
+	if (rc)
+		goto out;
+	rc = wait_for_completion_interruptible_timeout(&ep->re_done, wtimeout);
+	if (rc < 0)
+		goto out;
+	rc = ep->re_async_rc;
+	if (rc)
+		goto out;
+
+	return id;
+
+out:
+	rdma_destroy_id(id);
+	return ERR_PTR(rc);
+}
+
+static void rpcrdma_ep_destroy(struct kref *kref)
+{
+	struct rpcrdma_ep *ep = container_of(kref, struct rpcrdma_ep, re_kref);
+
+	if (ep->re_id->qp) {
+		rdma_destroy_qp(ep->re_id);
+		ep->re_id->qp = NULL;
+	}
+
+	if (ep->re_attr.recv_cq)
+		ib_free_cq(ep->re_attr.recv_cq);
+	ep->re_attr.recv_cq = NULL;
+	if (ep->re_attr.send_cq)
+		ib_free_cq(ep->re_attr.send_cq);
+	ep->re_attr.send_cq = NULL;
+
+	if (ep->re_pd)
+		ib_dealloc_pd(ep->re_pd);
+	ep->re_pd = NULL;
+
+	kfree(ep);
+	module_put(THIS_MODULE);
+}
+
+static noinline void rpcrdma_ep_get(struct rpcrdma_ep *ep)
+{
+	kref_get(&ep->re_kref);
+}
+
+/* Returns:
+ *     %0 if @ep still has a positive kref count, or
+ *     %1 if @ep was destroyed successfully.
+ */
+static noinline int rpcrdma_ep_put(struct rpcrdma_ep *ep)
+{
+	return kref_put(&ep->re_kref, rpcrdma_ep_destroy);
+}
+
+static int rpcrdma_ep_create(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_connect_private *pmsg;
+	struct ib_device *device;
+	struct rdma_cm_id *id;
+	struct rpcrdma_ep *ep;
+	int rc;
+
+	ep = kzalloc(sizeof(*ep), XPRTRDMA_GFP_FLAGS);
+	if (!ep)
+		return -ENOTCONN;
+	ep->re_xprt = &r_xprt->rx_xprt;
+	kref_init(&ep->re_kref);
+
+	id = rpcrdma_create_id(r_xprt, ep);
+	if (IS_ERR(id)) {
+		kfree(ep);
+		return PTR_ERR(id);
+	}
+	__module_get(THIS_MODULE);
+	device = id->device;
+	ep->re_id = id;
+	reinit_completion(&ep->re_done);
+
+	ep->re_max_requests = r_xprt->rx_xprt.max_reqs;
+	ep->re_inline_send = xprt_rdma_max_inline_write;
+	ep->re_inline_recv = xprt_rdma_max_inline_read;
+	rc = frwr_query_device(ep, device);
+	if (rc)
+		goto out_destroy;
+
+	r_xprt->rx_buf.rb_max_requests = cpu_to_be32(ep->re_max_requests);
+
+	ep->re_attr.srq = NULL;
+	ep->re_attr.cap.max_inline_data = 0;
+	ep->re_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
+	ep->re_attr.qp_type = IB_QPT_RC;
+	ep->re_attr.port_num = ~0;
+
+	ep->re_send_batch = ep->re_max_requests >> 3;
+	ep->re_send_count = ep->re_send_batch;
+	init_waitqueue_head(&ep->re_connect_wait);
+
+	ep->re_attr.send_cq = ib_alloc_cq_any(device, r_xprt,
+					      ep->re_attr.cap.max_send_wr,
+					      IB_POLL_WORKQUEUE);
+	if (IS_ERR(ep->re_attr.send_cq)) {
+		rc = PTR_ERR(ep->re_attr.send_cq);
+		ep->re_attr.send_cq = NULL;
+		goto out_destroy;
+	}
+
+	ep->re_attr.recv_cq = ib_alloc_cq_any(device, r_xprt,
+					      ep->re_attr.cap.max_recv_wr,
+					      IB_POLL_WORKQUEUE);
+	if (IS_ERR(ep->re_attr.recv_cq)) {
+		rc = PTR_ERR(ep->re_attr.recv_cq);
+		ep->re_attr.recv_cq = NULL;
+		goto out_destroy;
+	}
+	ep->re_receive_count = 0;
+
+	/* Initialize cma parameters */
+	memset(&ep->re_remote_cma, 0, sizeof(ep->re_remote_cma));
+
+	/* Prepare RDMA-CM private message */
+	pmsg = &ep->re_cm_private;
+	pmsg->cp_magic = rpcrdma_cmp_magic;
+	pmsg->cp_version = RPCRDMA_CMP_VERSION;
+	pmsg->cp_flags |= RPCRDMA_CMP_F_SND_W_INV_OK;
+	pmsg->cp_send_size = rpcrdma_encode_buffer_size(ep->re_inline_send);
+	pmsg->cp_recv_size = rpcrdma_encode_buffer_size(ep->re_inline_recv);
+	ep->re_remote_cma.private_data = pmsg;
+	ep->re_remote_cma.private_data_len = sizeof(*pmsg);
+
+	/* Client offers RDMA Read but does not initiate */
+	ep->re_remote_cma.initiator_depth = 0;
+	ep->re_remote_cma.responder_resources =
+		min_t(int, U8_MAX, 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->re_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->re_remote_cma.flow_control = 0;
+	ep->re_remote_cma.rnr_retry_count = 0;
+
+	ep->re_pd = ib_alloc_pd(device, 0);
+	if (IS_ERR(ep->re_pd)) {
+		rc = PTR_ERR(ep->re_pd);
+		ep->re_pd = NULL;
+		goto out_destroy;
+	}
+
+	rc = rdma_create_qp(id, ep->re_pd, &ep->re_attr);
+	if (rc)
+		goto out_destroy;
+
+	r_xprt->rx_ep = ep;
+	return 0;
+
+out_destroy:
+	rpcrdma_ep_put(ep);
+	rdma_destroy_id(id);
+	return rc;
+}
+
+/**
+ * rpcrdma_xprt_connect - Connect an unconnected transport
+ * @r_xprt: controlling transport instance
+ *
+ * Returns 0 on success or a negative errno.
+ */
+int rpcrdma_xprt_connect(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpc_xprt *xprt = &r_xprt->rx_xprt;
+	struct rpcrdma_ep *ep;
+	int rc;
+
+	rc = rpcrdma_ep_create(r_xprt);
+	if (rc)
+		return rc;
+	ep = r_xprt->rx_ep;
+
+	xprt_clear_connected(xprt);
+	rpcrdma_reset_cwnd(r_xprt);
+
+	/* Bump the ep's reference count while there are
+	 * outstanding Receives.
+	 */
+	rpcrdma_ep_get(ep);
+	rpcrdma_post_recvs(r_xprt, 1, true);
+
+	rc = rdma_connect(ep->re_id, &ep->re_remote_cma);
+	if (rc)
+		goto out;
+
+	if (xprt->reestablish_timeout < RPCRDMA_INIT_REEST_TO)
+		xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
+	wait_event_interruptible(ep->re_connect_wait,
+				 ep->re_connect_status != 0);
+	if (ep->re_connect_status <= 0) {
+		rc = ep->re_connect_status;
+		goto out;
+	}
+
+	rc = rpcrdma_sendctxs_create(r_xprt);
+	if (rc) {
+		rc = -ENOTCONN;
+		goto out;
+	}
+
+	rc = rpcrdma_reqs_setup(r_xprt);
+	if (rc) {
+		rc = -ENOTCONN;
+		goto out;
+	}
+	rpcrdma_mrs_create(r_xprt);
+	frwr_wp_create(r_xprt);
+
+out:
+	trace_xprtrdma_connect(r_xprt, rc);
+	return rc;
+}
+
+/**
+ * rpcrdma_xprt_disconnect - Disconnect underlying transport
+ * @r_xprt: controlling transport instance
+ *
+ * Caller serializes. Either the transport send lock is held,
+ * or we're being called to destroy the transport.
+ *
+ * On return, @r_xprt is completely divested of all hardware
+ * resources and prepared for the next ->connect operation.
+ */
+void rpcrdma_xprt_disconnect(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_ep *ep = r_xprt->rx_ep;
+	struct rdma_cm_id *id;
+	int rc;
+
+	if (!ep)
+		return;
+
+	id = ep->re_id;
+	rc = rdma_disconnect(id);
+	trace_xprtrdma_disconnect(r_xprt, rc);
+
+	rpcrdma_xprt_drain(r_xprt);
+	rpcrdma_reps_unmap(r_xprt);
+	rpcrdma_reqs_reset(r_xprt);
+	rpcrdma_mrs_destroy(r_xprt);
+	rpcrdma_sendctxs_destroy(r_xprt);
+
+	if (rpcrdma_ep_put(ep))
+		rdma_destroy_id(id);
+
+	r_xprt->rx_ep = NULL;
+}
+
+/* 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 rpcrdma_xprt_drain has flushed all remaining
+ * Send requests.
+ */
+static void rpcrdma_sendctxs_destroy(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	unsigned long i;
+
+	if (!buf->rb_sc_ctxs)
+		return;
+	for (i = 0; i <= buf->rb_sc_last; i++)
+		kfree(buf->rb_sc_ctxs[i]);
+	kfree(buf->rb_sc_ctxs);
+	buf->rb_sc_ctxs = NULL;
+}
+
+static struct rpcrdma_sendctx *rpcrdma_sendctx_create(struct rpcrdma_ep *ep)
+{
+	struct rpcrdma_sendctx *sc;
+
+	sc = kzalloc(struct_size(sc, sc_sges, ep->re_attr.cap.max_send_sge),
+		     XPRTRDMA_GFP_FLAGS);
+	if (!sc)
+		return NULL;
+
+	sc->sc_cqe.done = rpcrdma_wc_send;
+	sc->sc_cid.ci_queue_id = ep->re_attr.send_cq->res.id;
+	sc->sc_cid.ci_completion_id =
+		atomic_inc_return(&ep->re_completion_ids);
+	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 = r_xprt->rx_ep->re_max_requests + RPCRDMA_MAX_BC_REQUESTS;
+	buf->rb_sc_ctxs = kcalloc(i, sizeof(sc), XPRTRDMA_GFP_FLAGS);
+	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_ep);
+		if (!sc)
+			return -ENOMEM;
+
+		buf->rb_sc_ctxs[i] = sc;
+	}
+
+	buf->rb_sc_head = 0;
+	buf->rb_sc_tail = 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
+ * @r_xprt: controlling transport instance
+ *
+ * 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 transport), and
+ * provides an effective memory barrier that flushes the new value
+ * of rb_sc_head.
+ */
+struct rpcrdma_sendctx *rpcrdma_sendctx_get_locked(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	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.
+	 */
+	xprt_wait_for_buffer_space(&r_xprt->rx_xprt);
+	r_xprt->rx_stats.empty_sendctx_q++;
+	return NULL;
+}
+
+/**
+ * rpcrdma_sendctx_put_locked - Release a send context
+ * @r_xprt: controlling transport instance
+ * @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 transport).
+ */
+static void rpcrdma_sendctx_put_locked(struct rpcrdma_xprt *r_xprt,
+				       struct rpcrdma_sendctx *sc)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	unsigned long next_tail;
+
+	/* Unmap SGEs of previously completed but 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_sendctx_unmap(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);
+
+	xprt_write_space(&r_xprt->rx_xprt);
+}
+
+static void
+rpcrdma_mrs_create(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_ep *ep = r_xprt->rx_ep;
+	struct ib_device *device = ep->re_id->device;
+	unsigned int count;
+
+	/* Try to allocate enough to perform one full-sized I/O */
+	for (count = 0; count < ep->re_max_rdma_segs; count++) {
+		struct rpcrdma_mr *mr;
+		int rc;
+
+		mr = kzalloc_node(sizeof(*mr), XPRTRDMA_GFP_FLAGS,
+				  ibdev_to_node(device));
+		if (!mr)
+			break;
+
+		rc = frwr_mr_init(r_xprt, mr);
+		if (rc) {
+			kfree(mr);
+			break;
+		}
+
+		spin_lock(&buf->rb_lock);
+		rpcrdma_mr_push(mr, &buf->rb_mrs);
+		list_add(&mr->mr_all, &buf->rb_all_mrs);
+		spin_unlock(&buf->rb_lock);
+	}
+
+	r_xprt->rx_stats.mrs_allocated += count;
+	trace_xprtrdma_createmrs(r_xprt, count);
+}
+
+static void
+rpcrdma_mr_refresh_worker(struct work_struct *work)
+{
+	struct rpcrdma_buffer *buf = container_of(work, struct rpcrdma_buffer,
+						  rb_refresh_worker);
+	struct rpcrdma_xprt *r_xprt = container_of(buf, struct rpcrdma_xprt,
+						   rx_buf);
+
+	rpcrdma_mrs_create(r_xprt);
+	xprt_write_space(&r_xprt->rx_xprt);
+}
+
+/**
+ * rpcrdma_mrs_refresh - Wake the MR refresh worker
+ * @r_xprt: controlling transport instance
+ *
+ */
+void rpcrdma_mrs_refresh(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_ep *ep = r_xprt->rx_ep;
+
+	/* If there is no underlying connection, it's no use
+	 * to wake the refresh worker.
+	 */
+	if (ep->re_connect_status != 1)
+		return;
+	queue_work(system_highpri_wq, &buf->rb_refresh_worker);
+}
+
+/**
+ * rpcrdma_req_create - Allocate an rpcrdma_req object
+ * @r_xprt: controlling r_xprt
+ * @size: initial size, in bytes, of send and receive buffers
+ *
+ * Returns an allocated and fully initialized rpcrdma_req or NULL.
+ */
+struct rpcrdma_req *rpcrdma_req_create(struct rpcrdma_xprt *r_xprt,
+				       size_t size)
+{
+	struct rpcrdma_buffer *buffer = &r_xprt->rx_buf;
+	struct rpcrdma_req *req;
+
+	req = kzalloc(sizeof(*req), XPRTRDMA_GFP_FLAGS);
+	if (req == NULL)
+		goto out1;
+
+	req->rl_sendbuf = rpcrdma_regbuf_alloc(size, DMA_TO_DEVICE);
+	if (!req->rl_sendbuf)
+		goto out2;
+
+	req->rl_recvbuf = rpcrdma_regbuf_alloc(size, DMA_NONE);
+	if (!req->rl_recvbuf)
+		goto out3;
+
+	INIT_LIST_HEAD(&req->rl_free_mrs);
+	INIT_LIST_HEAD(&req->rl_registered);
+	spin_lock(&buffer->rb_lock);
+	list_add(&req->rl_all, &buffer->rb_allreqs);
+	spin_unlock(&buffer->rb_lock);
+	return req;
+
+out3:
+	rpcrdma_regbuf_free(req->rl_sendbuf);
+out2:
+	kfree(req);
+out1:
+	return NULL;
+}
+
+/**
+ * rpcrdma_req_setup - Per-connection instance setup of an rpcrdma_req object
+ * @r_xprt: controlling transport instance
+ * @req: rpcrdma_req object to set up
+ *
+ * Returns zero on success, and a negative errno on failure.
+ */
+int rpcrdma_req_setup(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
+{
+	struct rpcrdma_regbuf *rb;
+	size_t maxhdrsize;
+
+	/* Compute maximum header buffer size in bytes */
+	maxhdrsize = rpcrdma_fixed_maxsz + 3 +
+		     r_xprt->rx_ep->re_max_rdma_segs * rpcrdma_readchunk_maxsz;
+	maxhdrsize *= sizeof(__be32);
+	rb = rpcrdma_regbuf_alloc(__roundup_pow_of_two(maxhdrsize),
+				  DMA_TO_DEVICE);
+	if (!rb)
+		goto out;
+
+	if (!__rpcrdma_regbuf_dma_map(r_xprt, rb))
+		goto out_free;
+
+	req->rl_rdmabuf = rb;
+	xdr_buf_init(&req->rl_hdrbuf, rdmab_data(rb), rdmab_length(rb));
+	return 0;
+
+out_free:
+	rpcrdma_regbuf_free(rb);
+out:
+	return -ENOMEM;
+}
+
+/* ASSUMPTION: the rb_allreqs list is stable for the duration,
+ * and thus can be walked without holding rb_lock. Eg. the
+ * caller is holding the transport send lock to exclude
+ * device removal or disconnection.
+ */
+static int rpcrdma_reqs_setup(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_req *req;
+	int rc;
+
+	list_for_each_entry(req, &buf->rb_allreqs, rl_all) {
+		rc = rpcrdma_req_setup(r_xprt, req);
+		if (rc)
+			return rc;
+	}
+	return 0;
+}
+
+static void rpcrdma_req_reset(struct rpcrdma_req *req)
+{
+	/* Credits are valid for only one connection */
+	req->rl_slot.rq_cong = 0;
+
+	rpcrdma_regbuf_free(req->rl_rdmabuf);
+	req->rl_rdmabuf = NULL;
+
+	rpcrdma_regbuf_dma_unmap(req->rl_sendbuf);
+	rpcrdma_regbuf_dma_unmap(req->rl_recvbuf);
+
+	frwr_reset(req);
+}
+
+/* ASSUMPTION: the rb_allreqs list is stable for the duration,
+ * and thus can be walked without holding rb_lock. Eg. the
+ * caller is holding the transport send lock to exclude
+ * device removal or disconnection.
+ */
+static void rpcrdma_reqs_reset(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_req *req;
+
+	list_for_each_entry(req, &buf->rb_allreqs, rl_all)
+		rpcrdma_req_reset(req);
+}
+
+static noinline
+struct rpcrdma_rep *rpcrdma_rep_create(struct rpcrdma_xprt *r_xprt,
+				       bool temp)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_rep *rep;
+
+	rep = kzalloc(sizeof(*rep), XPRTRDMA_GFP_FLAGS);
+	if (rep == NULL)
+		goto out;
+
+	rep->rr_rdmabuf = rpcrdma_regbuf_alloc(r_xprt->rx_ep->re_inline_recv,
+					       DMA_FROM_DEVICE);
+	if (!rep->rr_rdmabuf)
+		goto out_free;
+
+	rep->rr_cid.ci_completion_id =
+		atomic_inc_return(&r_xprt->rx_ep->re_completion_ids);
+
+	xdr_buf_init(&rep->rr_hdrbuf, rdmab_data(rep->rr_rdmabuf),
+		     rdmab_length(rep->rr_rdmabuf));
+	rep->rr_cqe.done = rpcrdma_wc_receive;
+	rep->rr_rxprt = r_xprt;
+	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_all, &buf->rb_all_reps);
+	spin_unlock(&buf->rb_lock);
+	return rep;
+
+out_free:
+	kfree(rep);
+out:
+	return NULL;
+}
+
+static void rpcrdma_rep_free(struct rpcrdma_rep *rep)
+{
+	rpcrdma_regbuf_free(rep->rr_rdmabuf);
+	kfree(rep);
+}
+
+static void rpcrdma_rep_destroy(struct rpcrdma_rep *rep)
+{
+	struct rpcrdma_buffer *buf = &rep->rr_rxprt->rx_buf;
+
+	spin_lock(&buf->rb_lock);
+	list_del(&rep->rr_all);
+	spin_unlock(&buf->rb_lock);
+
+	rpcrdma_rep_free(rep);
+}
+
+static struct rpcrdma_rep *rpcrdma_rep_get_locked(struct rpcrdma_buffer *buf)
+{
+	struct llist_node *node;
+
+	/* Calls to llist_del_first are required to be serialized */
+	node = llist_del_first(&buf->rb_free_reps);
+	if (!node)
+		return NULL;
+	return llist_entry(node, struct rpcrdma_rep, rr_node);
+}
+
+/**
+ * rpcrdma_rep_put - Release rpcrdma_rep back to free list
+ * @buf: buffer pool
+ * @rep: rep to release
+ *
+ */
+void rpcrdma_rep_put(struct rpcrdma_buffer *buf, struct rpcrdma_rep *rep)
+{
+	llist_add(&rep->rr_node, &buf->rb_free_reps);
+}
+
+/* Caller must ensure the QP is quiescent (RQ is drained) before
+ * invoking this function, to guarantee rb_all_reps is not
+ * changing.
+ */
+static void rpcrdma_reps_unmap(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_rep *rep;
+
+	list_for_each_entry(rep, &buf->rb_all_reps, rr_all) {
+		rpcrdma_regbuf_dma_unmap(rep->rr_rdmabuf);
+		rep->rr_temp = true;	/* Mark this rep for destruction */
+	}
+}
+
+static void rpcrdma_reps_destroy(struct rpcrdma_buffer *buf)
+{
+	struct rpcrdma_rep *rep;
+
+	spin_lock(&buf->rb_lock);
+	while ((rep = list_first_entry_or_null(&buf->rb_all_reps,
+					       struct rpcrdma_rep,
+					       rr_all)) != NULL) {
+		list_del(&rep->rr_all);
+		spin_unlock(&buf->rb_lock);
+
+		rpcrdma_rep_free(rep);
+
+		spin_lock(&buf->rb_lock);
+	}
+	spin_unlock(&buf->rb_lock);
+}
+
+/**
+ * rpcrdma_buffer_create - Create initial set of req/rep objects
+ * @r_xprt: transport instance to (re)initialize
+ *
+ * Returns zero on success, otherwise a negative errno.
+ */
+int rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	int i, rc;
+
+	buf->rb_bc_srv_max_requests = 0;
+	spin_lock_init(&buf->rb_lock);
+	INIT_LIST_HEAD(&buf->rb_mrs);
+	INIT_LIST_HEAD(&buf->rb_all_mrs);
+	INIT_WORK(&buf->rb_refresh_worker, rpcrdma_mr_refresh_worker);
+
+	INIT_LIST_HEAD(&buf->rb_send_bufs);
+	INIT_LIST_HEAD(&buf->rb_allreqs);
+	INIT_LIST_HEAD(&buf->rb_all_reps);
+
+	rc = -ENOMEM;
+	for (i = 0; i < r_xprt->rx_xprt.max_reqs; i++) {
+		struct rpcrdma_req *req;
+
+		req = rpcrdma_req_create(r_xprt,
+					 RPCRDMA_V1_DEF_INLINE_SIZE * 2);
+		if (!req)
+			goto out;
+		list_add(&req->rl_list, &buf->rb_send_bufs);
+	}
+
+	init_llist_head(&buf->rb_free_reps);
+
+	return 0;
+out:
+	rpcrdma_buffer_destroy(buf);
+	return rc;
+}
+
+/**
+ * rpcrdma_req_destroy - Destroy an rpcrdma_req object
+ * @req: unused object to be destroyed
+ *
+ * Relies on caller holding the transport send lock to protect
+ * removing req->rl_all from buf->rb_all_reqs safely.
+ */
+void rpcrdma_req_destroy(struct rpcrdma_req *req)
+{
+	struct rpcrdma_mr *mr;
+
+	list_del(&req->rl_all);
+
+	while ((mr = rpcrdma_mr_pop(&req->rl_free_mrs))) {
+		struct rpcrdma_buffer *buf = &mr->mr_xprt->rx_buf;
+
+		spin_lock(&buf->rb_lock);
+		list_del(&mr->mr_all);
+		spin_unlock(&buf->rb_lock);
+
+		frwr_mr_release(mr);
+	}
+
+	rpcrdma_regbuf_free(req->rl_recvbuf);
+	rpcrdma_regbuf_free(req->rl_sendbuf);
+	rpcrdma_regbuf_free(req->rl_rdmabuf);
+	kfree(req);
+}
+
+/**
+ * rpcrdma_mrs_destroy - Release all of a transport's MRs
+ * @r_xprt: controlling transport instance
+ *
+ * Relies on caller holding the transport send lock to protect
+ * removing mr->mr_list from req->rl_free_mrs safely.
+ */
+static void rpcrdma_mrs_destroy(struct rpcrdma_xprt *r_xprt)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_mr *mr;
+
+	cancel_work_sync(&buf->rb_refresh_worker);
+
+	spin_lock(&buf->rb_lock);
+	while ((mr = list_first_entry_or_null(&buf->rb_all_mrs,
+					      struct rpcrdma_mr,
+					      mr_all)) != NULL) {
+		list_del(&mr->mr_list);
+		list_del(&mr->mr_all);
+		spin_unlock(&buf->rb_lock);
+
+		frwr_mr_release(mr);
+
+		spin_lock(&buf->rb_lock);
+	}
+	spin_unlock(&buf->rb_lock);
+}
+
+/**
+ * rpcrdma_buffer_destroy - Release all hw resources
+ * @buf: root control block for resources
+ *
+ * ORDERING: relies on a prior rpcrdma_xprt_drain :
+ * - No more Send or Receive completions can occur
+ * - All MRs, reps, and reqs are returned to their free lists
+ */
+void
+rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf)
+{
+	rpcrdma_reps_destroy(buf);
+
+	while (!list_empty(&buf->rb_send_bufs)) {
+		struct rpcrdma_req *req;
+
+		req = list_first_entry(&buf->rb_send_bufs,
+				       struct rpcrdma_req, rl_list);
+		list_del(&req->rl_list);
+		rpcrdma_req_destroy(req);
+	}
+}
+
+/**
+ * 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;
+
+	spin_lock(&buf->rb_lock);
+	mr = rpcrdma_mr_pop(&buf->rb_mrs);
+	spin_unlock(&buf->rb_lock);
+	return mr;
+}
+
+/**
+ * rpcrdma_reply_put - Put reply buffers back into pool
+ * @buffers: buffer pool
+ * @req: object to return
+ *
+ */
+void rpcrdma_reply_put(struct rpcrdma_buffer *buffers, struct rpcrdma_req *req)
+{
+	if (req->rl_reply) {
+		rpcrdma_rep_put(buffers, req->rl_reply);
+		req->rl_reply = NULL;
+	}
+}
+
+/**
+ * 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
+ * @buffers: buffer pool
+ * @req: object to return
+ *
+ */
+void rpcrdma_buffer_put(struct rpcrdma_buffer *buffers, struct rpcrdma_req *req)
+{
+	rpcrdma_reply_put(buffers, req);
+
+	spin_lock(&buffers->rb_lock);
+	list_add(&req->rl_list, &buffers->rb_send_bufs);
+	spin_unlock(&buffers->rb_lock);
+}
+
+/* Returns a pointer to a rpcrdma_regbuf object, or NULL.
+ *
+ * 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 frwr_map.
+ */
+static struct rpcrdma_regbuf *
+rpcrdma_regbuf_alloc(size_t size, enum dma_data_direction direction)
+{
+	struct rpcrdma_regbuf *rb;
+
+	rb = kmalloc(sizeof(*rb), XPRTRDMA_GFP_FLAGS);
+	if (!rb)
+		return NULL;
+	rb->rg_data = kmalloc(size, XPRTRDMA_GFP_FLAGS);
+	if (!rb->rg_data) {
+		kfree(rb);
+		return NULL;
+	}
+
+	rb->rg_device = NULL;
+	rb->rg_direction = direction;
+	rb->rg_iov.length = size;
+	return rb;
+}
+
+/**
+ * rpcrdma_regbuf_realloc - re-allocate a SEND/RECV buffer
+ * @rb: regbuf to reallocate
+ * @size: size of buffer to be allocated, in bytes
+ * @flags: GFP flags
+ *
+ * Returns true if reallocation was successful. If false is
+ * returned, @rb is left untouched.
+ */
+bool rpcrdma_regbuf_realloc(struct rpcrdma_regbuf *rb, size_t size, gfp_t flags)
+{
+	void *buf;
+
+	buf = kmalloc(size, flags);
+	if (!buf)
+		return false;
+
+	rpcrdma_regbuf_dma_unmap(rb);
+	kfree(rb->rg_data);
+
+	rb->rg_data = buf;
+	rb->rg_iov.length = size;
+	return true;
+}
+
+/**
+ * __rpcrdma_regbuf_dma_map - DMA-map a regbuf
+ * @r_xprt: controlling transport instance
+ * @rb: regbuf to be mapped
+ *
+ * Returns true if the buffer is now DMA mapped to @r_xprt's device
+ */
+bool __rpcrdma_regbuf_dma_map(struct rpcrdma_xprt *r_xprt,
+			      struct rpcrdma_regbuf *rb)
+{
+	struct ib_device *device = r_xprt->rx_ep->re_id->device;
+
+	if (rb->rg_direction == DMA_NONE)
+		return false;
+
+	rb->rg_iov.addr = ib_dma_map_single(device, rdmab_data(rb),
+					    rdmab_length(rb), rb->rg_direction);
+	if (ib_dma_mapping_error(device, rdmab_addr(rb))) {
+		trace_xprtrdma_dma_maperr(rdmab_addr(rb));
+		return false;
+	}
+
+	rb->rg_device = device;
+	rb->rg_iov.lkey = r_xprt->rx_ep->re_pd->local_dma_lkey;
+	return true;
+}
+
+static void rpcrdma_regbuf_dma_unmap(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;
+}
+
+static void rpcrdma_regbuf_free(struct rpcrdma_regbuf *rb)
+{
+	rpcrdma_regbuf_dma_unmap(rb);
+	if (rb)
+		kfree(rb->rg_data);
+	kfree(rb);
+}
+
+/**
+ * rpcrdma_post_recvs - Refill the Receive Queue
+ * @r_xprt: controlling transport instance
+ * @needed: current credit grant
+ * @temp: mark Receive buffers to be deleted after one use
+ *
+ */
+void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, int needed, bool temp)
+{
+	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+	struct rpcrdma_ep *ep = r_xprt->rx_ep;
+	struct ib_recv_wr *wr, *bad_wr;
+	struct rpcrdma_rep *rep;
+	int count, rc;
+
+	rc = 0;
+	count = 0;
+
+	if (likely(ep->re_receive_count > needed))
+		goto out;
+	needed -= ep->re_receive_count;
+	if (!temp)
+		needed += RPCRDMA_MAX_RECV_BATCH;
+
+	if (atomic_inc_return(&ep->re_receiving) > 1)
+		goto out;
+
+	/* fast path: all needed reps can be found on the free list */
+	wr = NULL;
+	while (needed) {
+		rep = rpcrdma_rep_get_locked(buf);
+		if (rep && rep->rr_temp) {
+			rpcrdma_rep_destroy(rep);
+			continue;
+		}
+		if (!rep)
+			rep = rpcrdma_rep_create(r_xprt, temp);
+		if (!rep)
+			break;
+		if (!rpcrdma_regbuf_dma_map(r_xprt, rep->rr_rdmabuf)) {
+			rpcrdma_rep_put(buf, rep);
+			break;
+		}
+
+		rep->rr_cid.ci_queue_id = ep->re_attr.recv_cq->res.id;
+		trace_xprtrdma_post_recv(rep);
+		rep->rr_recv_wr.next = wr;
+		wr = &rep->rr_recv_wr;
+		--needed;
+		++count;
+	}
+	if (!wr)
+		goto out;
+
+	rc = ib_post_recv(ep->re_id->qp, wr,
+			  (const struct ib_recv_wr **)&bad_wr);
+	if (rc) {
+		trace_xprtrdma_post_recvs_err(r_xprt, rc);
+		for (wr = bad_wr; wr;) {
+			struct rpcrdma_rep *rep;
+
+			rep = container_of(wr, struct rpcrdma_rep, rr_recv_wr);
+			wr = wr->next;
+			rpcrdma_rep_put(buf, rep);
+			--count;
+		}
+	}
+	if (atomic_dec_return(&ep->re_receiving) > 0)
+		complete(&ep->re_done);
+
+out:
+	trace_xprtrdma_post_recvs(r_xprt, count);
+	ep->re_receive_count += count;
+	return;
+}