Merge tag 'nfs-for-4.6-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client updates from Trond Myklebust:
 "Highlights include:

  Features:
   - Add support for multiple NFSv4.1 callbacks in flight
   - Initial patchset for RPC multipath support
   - Adapt RPC/RDMA to use the new completion queue API

  Bugfixes and cleanups:
   - nfs4: nfs4_ff_layout_prepare_ds should return NULL if connection failed
   - Cleanups to remove nfs_inode_dio_wait and nfs4_file_fsync
   - Fix RPC/RDMA credit accounting
   - Properly handle RDMA_ERROR replies
   - xprtrdma: Do not wait if ib_post_send() fails
   - xprtrdma: Segment head and tail XDR buffers on page boundaries
   - xprtrdma cleanups for dprintk, physical_op_map and unused macros"

* tag 'nfs-for-4.6-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (35 commits)
  nfs/blocklayout: make sure making a aligned read request
  nfs4: nfs4_ff_layout_prepare_ds should return NULL if connection failed
  nfs: remove nfs_inode_dio_wait
  nfs: remove nfs4_file_fsync
  xprtrdma: Use new CQ API for RPC-over-RDMA client send CQs
  xprtrdma: Use an anonymous union in struct rpcrdma_mw
  xprtrdma: Use new CQ API for RPC-over-RDMA client receive CQs
  xprtrdma: Serialize credit accounting again
  xprtrdma: Properly handle RDMA_ERROR replies
  rpcrdma: Add RPCRDMA_HDRLEN_ERR
  xprtrdma: Do not wait if ib_post_send() fails
  xprtrdma: Segment head and tail XDR buffers on page boundaries
  xprtrdma: Clean up dprintk format string containing a newline
  xprtrdma: Clean up physical_op_map()
  xprtrdma: Clean up unused RPCRDMA_INLINE_PAD_THRESH macro
  NFS add callback_ops to nfs4_proc_bind_conn_to_session_callback
  pnfs/NFSv4.1: Add multipath capabilities to pNFS flexfiles servers over NFSv3
  SUNRPC: Allow addition of new transports to a struct rpc_clnt
  NFSv4.1: nfs4_proc_bind_conn_to_session must iterate over all connections
  SUNRPC: Make NFS swap work with multipath
  ...

14 files changed, 1020 insertions, 346 deletions

diff --git a/net/sunrpc/Makefile b/net/sunrpc/Makefile
index b512fbd9d79a..ea7ffa12e0f9 100644
--- a/net/sunrpc/Makefile
+++ b/net/sunrpc/Makefile
@@ -12,7 +12,8 @@ sunrpc-y := clnt.o xprt.o socklib.o xprtsock.o sched.o \
 	    svc.o svcsock.o svcauth.o svcauth_unix.o \
 	    addr.o rpcb_clnt.o timer.o xdr.o \
 	    sunrpc_syms.o cache.o rpc_pipe.o \
-	    svc_xprt.o
+	    svc_xprt.o \
+	    xprtmultipath.o
 sunrpc-$(CONFIG_SUNRPC_DEBUG) += debugfs.o
 sunrpc-$(CONFIG_SUNRPC_BACKCHANNEL) += backchannel_rqst.o
 sunrpc-$(CONFIG_PROC_FS) += stats.o
diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index cabf586f47d7..8c6bc795f060 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -1181,12 +1181,12 @@ static struct rpc_auth *
 gss_create(struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
 {
 	struct gss_auth *gss_auth;
-	struct rpc_xprt *xprt = rcu_access_pointer(clnt->cl_xprt);
+	struct rpc_xprt_switch *xps = rcu_access_pointer(clnt->cl_xpi.xpi_xpswitch);
 
 	while (clnt != clnt->cl_parent) {
 		struct rpc_clnt *parent = clnt->cl_parent;
 		/* Find the original parent for this transport */
-		if (rcu_access_pointer(parent->cl_xprt) != xprt)
+		if (rcu_access_pointer(parent->cl_xpi.xpi_xpswitch) != xps)
 			break;
 		clnt = parent;
 	}
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index b7f21044f4d8..7e0c9bf22df8 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -354,6 +354,7 @@ static void rpc_free_clid(struct rpc_clnt *clnt)
 }
 
 static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args,
+		struct rpc_xprt_switch *xps,
 		struct rpc_xprt *xprt,
 		struct rpc_clnt *parent)
 {
@@ -411,6 +412,8 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args,
 	}
 
 	rpc_clnt_set_transport(clnt, xprt, timeout);
+	xprt_iter_init(&clnt->cl_xpi, xps);
+	xprt_switch_put(xps);
 
 	clnt->cl_rtt = &clnt->cl_rtt_default;
 	rpc_init_rtt(&clnt->cl_rtt_default, clnt->cl_timeout->to_initval);
@@ -438,6 +441,7 @@ out_no_clid:
 out_err:
 	rpciod_down();
 out_no_rpciod:
+	xprt_switch_put(xps);
 	xprt_put(xprt);
 	return ERR_PTR(err);
 }
@@ -446,8 +450,13 @@ struct rpc_clnt *rpc_create_xprt(struct rpc_create_args *args,
 					struct rpc_xprt *xprt)
 {
 	struct rpc_clnt *clnt = NULL;
+	struct rpc_xprt_switch *xps;
 
-	clnt = rpc_new_client(args, xprt, NULL);
+	xps = xprt_switch_alloc(xprt, GFP_KERNEL);
+	if (xps == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	clnt = rpc_new_client(args, xps, xprt, NULL);
 	if (IS_ERR(clnt))
 		return clnt;
 
@@ -564,6 +573,7 @@ EXPORT_SYMBOL_GPL(rpc_create);
 static struct rpc_clnt *__rpc_clone_client(struct rpc_create_args *args,
 					   struct rpc_clnt *clnt)
 {
+	struct rpc_xprt_switch *xps;
 	struct rpc_xprt *xprt;
 	struct rpc_clnt *new;
 	int err;
@@ -571,13 +581,17 @@ static struct rpc_clnt *__rpc_clone_client(struct rpc_create_args *args,
 	err = -ENOMEM;
 	rcu_read_lock();
 	xprt = xprt_get(rcu_dereference(clnt->cl_xprt));
+	xps = xprt_switch_get(rcu_dereference(clnt->cl_xpi.xpi_xpswitch));
 	rcu_read_unlock();
-	if (xprt == NULL)
+	if (xprt == NULL || xps == NULL) {
+		xprt_put(xprt);
+		xprt_switch_put(xps);
 		goto out_err;
+	}
 	args->servername = xprt->servername;
 	args->nodename = clnt->cl_nodename;
 
-	new = rpc_new_client(args, xprt, clnt);
+	new = rpc_new_client(args, xps, xprt, clnt);
 	if (IS_ERR(new)) {
 		err = PTR_ERR(new);
 		goto out_err;
@@ -657,6 +671,7 @@ int rpc_switch_client_transport(struct rpc_clnt *clnt,
 {
 	const struct rpc_timeout *old_timeo;
 	rpc_authflavor_t pseudoflavor;
+	struct rpc_xprt_switch *xps, *oldxps;
 	struct rpc_xprt *xprt, *old;
 	struct rpc_clnt *parent;
 	int err;
@@ -668,10 +683,17 @@ int rpc_switch_client_transport(struct rpc_clnt *clnt,
 		return PTR_ERR(xprt);
 	}
 
+	xps = xprt_switch_alloc(xprt, GFP_KERNEL);
+	if (xps == NULL) {
+		xprt_put(xprt);
+		return -ENOMEM;
+	}
+
 	pseudoflavor = clnt->cl_auth->au_flavor;
 
 	old_timeo = clnt->cl_timeout;
 	old = rpc_clnt_set_transport(clnt, xprt, timeout);
+	oldxps = xprt_iter_xchg_switch(&clnt->cl_xpi, xps);
 
 	rpc_unregister_client(clnt);
 	__rpc_clnt_remove_pipedir(clnt);
@@ -697,20 +719,74 @@ int rpc_switch_client_transport(struct rpc_clnt *clnt,
 	synchronize_rcu();
 	if (parent != clnt)
 		rpc_release_client(parent);
+	xprt_switch_put(oldxps);
 	xprt_put(old);
 	dprintk("RPC:       replaced xprt for clnt %p\n", clnt);
 	return 0;
 
 out_revert:
+	xps = xprt_iter_xchg_switch(&clnt->cl_xpi, oldxps);
 	rpc_clnt_set_transport(clnt, old, old_timeo);
 	clnt->cl_parent = parent;
 	rpc_client_register(clnt, pseudoflavor, NULL);
+	xprt_switch_put(xps);
 	xprt_put(xprt);
 	dprintk("RPC:       failed to switch xprt for clnt %p\n", clnt);
 	return err;
 }
 EXPORT_SYMBOL_GPL(rpc_switch_client_transport);
 
+static
+int rpc_clnt_xprt_iter_init(struct rpc_clnt *clnt, struct rpc_xprt_iter *xpi)
+{
+	struct rpc_xprt_switch *xps;
+
+	rcu_read_lock();
+	xps = xprt_switch_get(rcu_dereference(clnt->cl_xpi.xpi_xpswitch));
+	rcu_read_unlock();
+	if (xps == NULL)
+		return -EAGAIN;
+	xprt_iter_init_listall(xpi, xps);
+	xprt_switch_put(xps);
+	return 0;
+}
+
+/**
+ * rpc_clnt_iterate_for_each_xprt - Apply a function to all transports
+ * @clnt: pointer to client
+ * @fn: function to apply
+ * @data: void pointer to function data
+ *
+ * Iterates through the list of RPC transports currently attached to the
+ * client and applies the function fn(clnt, xprt, data).
+ *
+ * On error, the iteration stops, and the function returns the error value.
+ */
+int rpc_clnt_iterate_for_each_xprt(struct rpc_clnt *clnt,
+		int (*fn)(struct rpc_clnt *, struct rpc_xprt *, void *),
+		void *data)
+{
+	struct rpc_xprt_iter xpi;
+	int ret;
+
+	ret = rpc_clnt_xprt_iter_init(clnt, &xpi);
+	if (ret)
+		return ret;
+	for (;;) {
+		struct rpc_xprt *xprt = xprt_iter_get_next(&xpi);
+
+		if (!xprt)
+			break;
+		ret = fn(clnt, xprt, data);
+		xprt_put(xprt);
+		if (ret < 0)
+			break;
+	}
+	xprt_iter_destroy(&xpi);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rpc_clnt_iterate_for_each_xprt);
+
 /*
  * Kill all tasks for the given client.
  * XXX: kill their descendants as well?
@@ -783,6 +859,7 @@ rpc_free_client(struct rpc_clnt *clnt)
 	rpc_free_iostats(clnt->cl_metrics);
 	clnt->cl_metrics = NULL;
 	xprt_put(rcu_dereference_raw(clnt->cl_xprt));
+	xprt_iter_destroy(&clnt->cl_xpi);
 	rpciod_down();
 	rpc_free_clid(clnt);
 	kfree(clnt);
@@ -868,6 +945,7 @@ EXPORT_SYMBOL_GPL(rpc_bind_new_program);
 void rpc_task_release_client(struct rpc_task *task)
 {
 	struct rpc_clnt *clnt = task->tk_client;
+	struct rpc_xprt *xprt = task->tk_xprt;
 
 	if (clnt != NULL) {
 		/* Remove from client task list */
@@ -878,13 +956,22 @@ void rpc_task_release_client(struct rpc_task *task)
 
 		rpc_release_client(clnt);
 	}
+
+	if (xprt != NULL) {
+		task->tk_xprt = NULL;
+
+		xprt_put(xprt);
+	}
 }
 
 static
 void rpc_task_set_client(struct rpc_task *task, struct rpc_clnt *clnt)
 {
+
 	if (clnt != NULL) {
 		rpc_task_release_client(task);
+		if (task->tk_xprt == NULL)
+			task->tk_xprt = xprt_iter_get_next(&clnt->cl_xpi);
 		task->tk_client = clnt;
 		atomic_inc(&clnt->cl_count);
 		if (clnt->cl_softrtry)
@@ -900,14 +987,6 @@ void rpc_task_set_client(struct rpc_task *task, struct rpc_clnt *clnt)
 	}
 }
 
-void rpc_task_reset_client(struct rpc_task *task, struct rpc_clnt *clnt)
-{
-	rpc_task_release_client(task);
-	rpc_task_set_client(task, clnt);
-}
-EXPORT_SYMBOL_GPL(rpc_task_reset_client);
-
-
 static void
 rpc_task_set_rpc_message(struct rpc_task *task, const struct rpc_message *msg)
 {
@@ -2104,11 +2183,9 @@ call_timeout(struct rpc_task *task)
 	}
 	if (RPC_IS_SOFT(task)) {
 		if (clnt->cl_chatty) {
-			rcu_read_lock();
 			printk(KERN_NOTICE "%s: server %s not responding, timed out\n",
 				clnt->cl_program->name,
-				rcu_dereference(clnt->cl_xprt)->servername);
-			rcu_read_unlock();
+				task->tk_xprt->servername);
 		}
 		if (task->tk_flags & RPC_TASK_TIMEOUT)
 			rpc_exit(task, -ETIMEDOUT);
@@ -2120,11 +2197,9 @@ call_timeout(struct rpc_task *task)
 	if (!(task->tk_flags & RPC_CALL_MAJORSEEN)) {
 		task->tk_flags |= RPC_CALL_MAJORSEEN;
 		if (clnt->cl_chatty) {
-			rcu_read_lock();
 			printk(KERN_NOTICE "%s: server %s not responding, still trying\n",
 			clnt->cl_program->name,
-			rcu_dereference(clnt->cl_xprt)->servername);
-			rcu_read_unlock();
+			task->tk_xprt->servername);
 		}
 	}
 	rpc_force_rebind(clnt);
@@ -2154,11 +2229,9 @@ call_decode(struct rpc_task *task)
 
 	if (task->tk_flags & RPC_CALL_MAJORSEEN) {
 		if (clnt->cl_chatty) {
-			rcu_read_lock();
 			printk(KERN_NOTICE "%s: server %s OK\n",
 				clnt->cl_program->name,
-				rcu_dereference(clnt->cl_xprt)->servername);
-			rcu_read_unlock();
+				task->tk_xprt->servername);
 		}
 		task->tk_flags &= ~RPC_CALL_MAJORSEEN;
 	}
@@ -2312,11 +2385,9 @@ rpc_verify_header(struct rpc_task *task)
 			task->tk_action = call_bind;
 			goto out_retry;
 		case RPC_AUTH_TOOWEAK:
-			rcu_read_lock();
 			printk(KERN_NOTICE "RPC: server %s requires stronger "
 			       "authentication.\n",
-			       rcu_dereference(clnt->cl_xprt)->servername);
-			rcu_read_unlock();
+			       task->tk_xprt->servername);
 			break;
 		default:
 			dprintk("RPC: %5u %s: unknown auth error: %x\n",
@@ -2341,27 +2412,27 @@ rpc_verify_header(struct rpc_task *task)
 	case RPC_SUCCESS:
 		return p;
 	case RPC_PROG_UNAVAIL:
-		dprintk_rcu("RPC: %5u %s: program %u is unsupported "
+		dprintk("RPC: %5u %s: program %u is unsupported "
 				"by server %s\n", task->tk_pid, __func__,
 				(unsigned int)clnt->cl_prog,
-				rcu_dereference(clnt->cl_xprt)->servername);
+				task->tk_xprt->servername);
 		error = -EPFNOSUPPORT;
 		goto out_err;
 	case RPC_PROG_MISMATCH:
-		dprintk_rcu("RPC: %5u %s: program %u, version %u unsupported "
+		dprintk("RPC: %5u %s: program %u, version %u unsupported "
 				"by server %s\n", task->tk_pid, __func__,
 				(unsigned int)clnt->cl_prog,
 				(unsigned int)clnt->cl_vers,
-				rcu_dereference(clnt->cl_xprt)->servername);
+				task->tk_xprt->servername);
 		error = -EPROTONOSUPPORT;
 		goto out_err;
 	case RPC_PROC_UNAVAIL:
-		dprintk_rcu("RPC: %5u %s: proc %s unsupported by program %u, "
+		dprintk("RPC: %5u %s: proc %s unsupported by program %u, "
 				"version %u on server %s\n",
 				task->tk_pid, __func__,
 				rpc_proc_name(task),
 				clnt->cl_prog, clnt->cl_vers,
-				rcu_dereference(clnt->cl_xprt)->servername);
+				task->tk_xprt->servername);
 		error = -EOPNOTSUPP;
 		goto out_err;
 	case RPC_GARBAGE_ARGS:
@@ -2421,7 +2492,10 @@ static int rpc_ping(struct rpc_clnt *clnt)
 	return err;
 }
 
-struct rpc_task *rpc_call_null(struct rpc_clnt *clnt, struct rpc_cred *cred, int flags)
+static
+struct rpc_task *rpc_call_null_helper(struct rpc_clnt *clnt,
+		struct rpc_xprt *xprt, struct rpc_cred *cred, int flags,
+		const struct rpc_call_ops *ops, void *data)
 {
 	struct rpc_message msg = {
 		.rpc_proc = &rpcproc_null,
@@ -2429,14 +2503,140 @@ struct rpc_task *rpc_call_null(struct rpc_clnt *clnt, struct rpc_cred *cred, int
 	};
 	struct rpc_task_setup task_setup_data = {
 		.rpc_client = clnt,
+		.rpc_xprt = xprt,
 		.rpc_message = &msg,
-		.callback_ops = &rpc_default_ops,
+		.callback_ops = (ops != NULL) ? ops : &rpc_default_ops,
+		.callback_data = data,
 		.flags = flags,
 	};
+
 	return rpc_run_task(&task_setup_data);
 }
+
+struct rpc_task *rpc_call_null(struct rpc_clnt *clnt, struct rpc_cred *cred, int flags)
+{
+	return rpc_call_null_helper(clnt, NULL, cred, flags, NULL, NULL);
+}
 EXPORT_SYMBOL_GPL(rpc_call_null);
 
+struct rpc_cb_add_xprt_calldata {
+	struct rpc_xprt_switch *xps;
+	struct rpc_xprt *xprt;
+};
+
+static void rpc_cb_add_xprt_done(struct rpc_task *task, void *calldata)
+{
+	struct rpc_cb_add_xprt_calldata *data = calldata;
+
+	if (task->tk_status == 0)
+		rpc_xprt_switch_add_xprt(data->xps, data->xprt);
+}
+
+static void rpc_cb_add_xprt_release(void *calldata)
+{
+	struct rpc_cb_add_xprt_calldata *data = calldata;
+
+	xprt_put(data->xprt);
+	xprt_switch_put(data->xps);
+	kfree(data);
+}
+
+const static struct rpc_call_ops rpc_cb_add_xprt_call_ops = {
+	.rpc_call_done = rpc_cb_add_xprt_done,
+	.rpc_release = rpc_cb_add_xprt_release,
+};
+
+/**
+ * rpc_clnt_test_and_add_xprt - Test and add a new transport to a rpc_clnt
+ * @clnt: pointer to struct rpc_clnt
+ * @xps: pointer to struct rpc_xprt_switch,
+ * @xprt: pointer struct rpc_xprt
+ * @dummy: unused
+ */
+int rpc_clnt_test_and_add_xprt(struct rpc_clnt *clnt,
+		struct rpc_xprt_switch *xps, struct rpc_xprt *xprt,
+		void *dummy)
+{
+	struct rpc_cb_add_xprt_calldata *data;
+	struct rpc_cred *cred;
+	struct rpc_task *task;
+
+	data = kmalloc(sizeof(*data), GFP_NOFS);
+	if (!data)
+		return -ENOMEM;
+	data->xps = xprt_switch_get(xps);
+	data->xprt = xprt_get(xprt);
+
+	cred = authnull_ops.lookup_cred(NULL, NULL, 0);
+	task = rpc_call_null_helper(clnt, xprt, cred,
+			RPC_TASK_SOFT|RPC_TASK_SOFTCONN|RPC_TASK_ASYNC,
+			&rpc_cb_add_xprt_call_ops, data);
+	put_rpccred(cred);
+	if (IS_ERR(task))
+		return PTR_ERR(task);
+	rpc_put_task(task);
+	return 1;
+}
+EXPORT_SYMBOL_GPL(rpc_clnt_test_and_add_xprt);
+
+/**
+ * rpc_clnt_add_xprt - Add a new transport to a rpc_clnt
+ * @clnt: pointer to struct rpc_clnt
+ * @xprtargs: pointer to struct xprt_create
+ * @setup: callback to test and/or set up the connection
+ * @data: pointer to setup function data
+ *
+ * Creates a new transport using the parameters set in args and
+ * adds it to clnt.
+ * If ping is set, then test that connectivity succeeds before
+ * adding the new transport.
+ *
+ */
+int rpc_clnt_add_xprt(struct rpc_clnt *clnt,
+		struct xprt_create *xprtargs,
+		int (*setup)(struct rpc_clnt *,
+			struct rpc_xprt_switch *,
+			struct rpc_xprt *,
+			void *),
+		void *data)
+{
+	struct rpc_xprt_switch *xps;
+	struct rpc_xprt *xprt;
+	unsigned char resvport;
+	int ret = 0;
+
+	rcu_read_lock();
+	xps = xprt_switch_get(rcu_dereference(clnt->cl_xpi.xpi_xpswitch));
+	xprt = xprt_iter_xprt(&clnt->cl_xpi);
+	if (xps == NULL || xprt == NULL) {
+		rcu_read_unlock();
+		return -EAGAIN;
+	}
+	resvport = xprt->resvport;
+	rcu_read_unlock();
+
+	xprt = xprt_create_transport(xprtargs);
+	if (IS_ERR(xprt)) {
+		ret = PTR_ERR(xprt);
+		goto out_put_switch;
+	}
+	xprt->resvport = resvport;
+
+	rpc_xprt_switch_set_roundrobin(xps);
+	if (setup) {
+		ret = setup(clnt, xps, xprt, data);
+		if (ret != 0)
+			goto out_put_xprt;
+	}
+	rpc_xprt_switch_add_xprt(xps, xprt);
+out_put_xprt:
+	xprt_put(xprt);
+out_put_switch:
+	xprt_switch_put(xps);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rpc_clnt_add_xprt);
+
 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
 static void rpc_show_header(void)
 {
@@ -2483,57 +2683,39 @@ void rpc_show_tasks(struct net *net)
 #endif
 
 #if IS_ENABLED(CONFIG_SUNRPC_SWAP)
+static int
+rpc_clnt_swap_activate_callback(struct rpc_clnt *clnt,
+		struct rpc_xprt *xprt,
+		void *dummy)
+{
+	return xprt_enable_swap(xprt);
+}
+
 int
 rpc_clnt_swap_activate(struct rpc_clnt *clnt)
 {
-	int ret = 0;
-	struct rpc_xprt	*xprt;
-
-	if (atomic_inc_return(&clnt->cl_swapper) == 1) {
-retry:
-		rcu_read_lock();
-		xprt = xprt_get(rcu_dereference(clnt->cl_xprt));
-		rcu_read_unlock();
-		if (!xprt) {
-			/*
-			 * If we didn't get a reference, then we likely are
-			 * racing with a migration event. Wait for a grace
-			 * period and try again.
-			 */
-			synchronize_rcu();
-			goto retry;
-		}
-
-		ret = xprt_enable_swap(xprt);
-		xprt_put(xprt);
-	}
-	return ret;
+	if (atomic_inc_return(&clnt->cl_swapper) == 1)
+		return rpc_clnt_iterate_for_each_xprt(clnt,
+				rpc_clnt_swap_activate_callback, NULL);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(rpc_clnt_swap_activate);
 
+static int
+rpc_clnt_swap_deactivate_callback(struct rpc_clnt *clnt,
+		struct rpc_xprt *xprt,
+		void *dummy)
+{
+	xprt_disable_swap(xprt);
+	return 0;
+}
+
 void
 rpc_clnt_swap_deactivate(struct rpc_clnt *clnt)
 {
-	struct rpc_xprt	*xprt;
-
-	if (atomic_dec_if_positive(&clnt->cl_swapper) == 0) {
-retry:
-		rcu_read_lock();
-		xprt = xprt_get(rcu_dereference(clnt->cl_xprt));
-		rcu_read_unlock();
-		if (!xprt) {
-			/*
-			 * If we didn't get a reference, then we likely are
-			 * racing with a migration event. Wait for a grace
-			 * period and try again.
-			 */
-			synchronize_rcu();
-			goto retry;
-		}
-
-		xprt_disable_swap(xprt);
-		xprt_put(xprt);
-	}
+	if (atomic_dec_if_positive(&clnt->cl_swapper) == 0)
+		rpc_clnt_iterate_for_each_xprt(clnt,
+				rpc_clnt_swap_deactivate_callback, NULL);
 }
 EXPORT_SYMBOL_GPL(rpc_clnt_swap_deactivate);
 #endif /* CONFIG_SUNRPC_SWAP */
diff --git a/net/sunrpc/rpcb_clnt.c b/net/sunrpc/rpcb_clnt.c
index cf5770d8f49a..5b30603596d0 100644
--- a/net/sunrpc/rpcb_clnt.c
+++ b/net/sunrpc/rpcb_clnt.c
@@ -648,10 +648,10 @@ static struct rpc_task *rpcb_call_async(struct rpc_clnt *rpcb_clnt, struct rpcbi
 static struct rpc_clnt *rpcb_find_transport_owner(struct rpc_clnt *clnt)
 {
 	struct rpc_clnt *parent = clnt->cl_parent;
-	struct rpc_xprt *xprt = rcu_dereference(clnt->cl_xprt);
+	struct rpc_xprt_switch *xps = rcu_access_pointer(clnt->cl_xpi.xpi_xpswitch);
 
 	while (parent != clnt) {
-		if (rcu_dereference(parent->cl_xprt) != xprt)
+		if (rcu_access_pointer(parent->cl_xpi.xpi_xpswitch) != xps)
 			break;
 		if (clnt->cl_autobind)
 			break;
@@ -683,11 +683,9 @@ void rpcb_getport_async(struct rpc_task *task)
 	int status;
 
 	rcu_read_lock();
-	do {
-		clnt = rpcb_find_transport_owner(task->tk_client);
-		xprt = xprt_get(rcu_dereference(clnt->cl_xprt));
-	} while (xprt == NULL);
+	clnt = rpcb_find_transport_owner(task->tk_client);
 	rcu_read_unlock();
+	xprt = xprt_get(task->tk_xprt);
 
 	dprintk("RPC: %5u %s(%s, %u, %u, %d)\n",
 		task->tk_pid, __func__,
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 73ad57a59989..fcfd48d263f6 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -909,6 +909,8 @@ static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *ta
 	/* Initialize workqueue for async tasks */
 	task->tk_workqueue = task_setup_data->workqueue;
 
+	task->tk_xprt = xprt_get(task_setup_data->rpc_xprt);
+
 	if (task->tk_ops->rpc_call_prepare != NULL)
 		task->tk_action = rpc_prepare_task;
 
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 37edea6fa92d..216a1385718a 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -48,6 +48,7 @@
 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/metrics.h>
 #include <linux/sunrpc/bc_xprt.h>
+#include <linux/rcupdate.h>
 
 #include <trace/events/sunrpc.h>
 
@@ -1166,7 +1167,7 @@ void xprt_free(struct rpc_xprt *xprt)
 {
 	put_net(xprt->xprt_net);
 	xprt_free_all_slots(xprt);
-	kfree(xprt);
+	kfree_rcu(xprt, rcu);
 }
 EXPORT_SYMBOL_GPL(xprt_free);
 
@@ -1180,7 +1181,7 @@ EXPORT_SYMBOL_GPL(xprt_free);
  */
 void xprt_reserve(struct rpc_task *task)
 {
-	struct rpc_xprt	*xprt;
+	struct rpc_xprt *xprt = task->tk_xprt;
 
 	task->tk_status = 0;
 	if (task->tk_rqstp != NULL)
@@ -1188,11 +1189,8 @@ void xprt_reserve(struct rpc_task *task)
 
 	task->tk_timeout = 0;
 	task->tk_status = -EAGAIN;
-	rcu_read_lock();
-	xprt = rcu_dereference(task->tk_client->cl_xprt);
 	if (!xprt_throttle_congested(xprt, task))
 		xprt->ops->alloc_slot(xprt, task);
-	rcu_read_unlock();
 }
 
 /**
@@ -1206,7 +1204,7 @@ void xprt_reserve(struct rpc_task *task)
  */
 void xprt_retry_reserve(struct rpc_task *task)
 {
-	struct rpc_xprt	*xprt;
+	struct rpc_xprt *xprt = task->tk_xprt;
 
 	task->tk_status = 0;
 	if (task->tk_rqstp != NULL)
@@ -1214,10 +1212,7 @@ void xprt_retry_reserve(struct rpc_task *task)
 
 	task->tk_timeout = 0;
 	task->tk_status = -EAGAIN;
-	rcu_read_lock();
-	xprt = rcu_dereference(task->tk_client->cl_xprt);
 	xprt->ops->alloc_slot(xprt, task);
-	rcu_read_unlock();
 }
 
 static inline __be32 xprt_alloc_xid(struct rpc_xprt *xprt)
@@ -1264,11 +1259,9 @@ void xprt_release(struct rpc_task *task)
 
 	if (req == NULL) {
 		if (task->tk_client) {
-			rcu_read_lock();
-			xprt = rcu_dereference(task->tk_client->cl_xprt);
+			xprt = task->tk_xprt;
 			if (xprt->snd_task == task)
 				xprt_release_write(xprt, task);
-			rcu_read_unlock();
 		}
 		return;
 	}
@@ -1307,7 +1300,7 @@ void xprt_release(struct rpc_task *task)
 
 static void xprt_init(struct rpc_xprt *xprt, struct net *net)
 {
-	atomic_set(&xprt->count, 1);
+	kref_init(&xprt->kref);
 
 	spin_lock_init(&xprt->transport_lock);
 	spin_lock_init(&xprt->reserve_lock);
@@ -1318,6 +1311,7 @@ static void xprt_init(struct rpc_xprt *xprt, struct net *net)
 	spin_lock_init(&xprt->bc_pa_lock);
 	INIT_LIST_HEAD(&xprt->bc_pa_list);
 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
+	INIT_LIST_HEAD(&xprt->xprt_switch);
 
 	xprt->last_used = jiffies;
 	xprt->cwnd = RPC_INITCWND;
@@ -1415,6 +1409,24 @@ static void xprt_destroy(struct rpc_xprt *xprt)
 	xprt->ops->destroy(xprt);
 }
 
+static void xprt_destroy_kref(struct kref *kref)
+{
+	xprt_destroy(container_of(kref, struct rpc_xprt, kref));
+}
+
+/**
+ * xprt_get - return a reference to an RPC transport.
+ * @xprt: pointer to the transport
+ *
+ */
+struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
+{
+	if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
+		return xprt;
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(xprt_get);
+
 /**
  * xprt_put - release a reference to an RPC transport.
  * @xprt: pointer to the transport
@@ -1422,7 +1434,7 @@ static void xprt_destroy(struct rpc_xprt *xprt)
  */
 void xprt_put(struct rpc_xprt *xprt)
 {
-	if (atomic_dec_and_test(&xprt->count))
-		xprt_destroy(xprt);
+	if (xprt != NULL)
+		kref_put(&xprt->kref, xprt_destroy_kref);
 }
 EXPORT_SYMBOL_GPL(xprt_put);
diff --git a/net/sunrpc/xprtmultipath.c b/net/sunrpc/xprtmultipath.c
new file mode 100644
index 000000000000..e7fd76975d86
--- /dev/null
+++ b/net/sunrpc/xprtmultipath.c
@@ -0,0 +1,475 @@
+/*
+ * Multipath support for RPC
+ *
+ * Copyright (c) 2015, 2016, Primary Data, Inc. All rights reserved.
+ *
+ * Trond Myklebust <trond.myklebust@primarydata.com>
+ *
+ */
+#include <linux/types.h>
+#include <linux/kref.h>
+#include <linux/list.h>
+#include <linux/rcupdate.h>
+#include <linux/rculist.h>
+#include <linux/slab.h>
+#include <asm/cmpxchg.h>
+#include <linux/spinlock.h>
+#include <linux/sunrpc/xprt.h>
+#include <linux/sunrpc/xprtmultipath.h>
+
+typedef struct rpc_xprt *(*xprt_switch_find_xprt_t)(struct list_head *head,
+		const struct rpc_xprt *cur);
+
+static const struct rpc_xprt_iter_ops rpc_xprt_iter_singular;
+static const struct rpc_xprt_iter_ops rpc_xprt_iter_roundrobin;
+static const struct rpc_xprt_iter_ops rpc_xprt_iter_listall;
+
+static void xprt_switch_add_xprt_locked(struct rpc_xprt_switch *xps,
+		struct rpc_xprt *xprt)
+{
+	if (unlikely(xprt_get(xprt) == NULL))
+		return;
+	list_add_tail_rcu(&xprt->xprt_switch, &xps->xps_xprt_list);
+	smp_wmb();
+	if (xps->xps_nxprts == 0)
+		xps->xps_net = xprt->xprt_net;
+	xps->xps_nxprts++;
+}
+
+/**
+ * rpc_xprt_switch_add_xprt - Add a new rpc_xprt to an rpc_xprt_switch
+ * @xps: pointer to struct rpc_xprt_switch
+ * @xprt: pointer to struct rpc_xprt
+ *
+ * Adds xprt to the end of the list of struct rpc_xprt in xps.
+ */
+void rpc_xprt_switch_add_xprt(struct rpc_xprt_switch *xps,
+		struct rpc_xprt *xprt)
+{
+	if (xprt == NULL)
+		return;
+	spin_lock(&xps->xps_lock);
+	if (xps->xps_net == xprt->xprt_net || xps->xps_net == NULL)
+		xprt_switch_add_xprt_locked(xps, xprt);
+	spin_unlock(&xps->xps_lock);
+}
+
+static void xprt_switch_remove_xprt_locked(struct rpc_xprt_switch *xps,
+		struct rpc_xprt *xprt)
+{
+	if (unlikely(xprt == NULL))
+		return;
+	xps->xps_nxprts--;
+	if (xps->xps_nxprts == 0)
+		xps->xps_net = NULL;
+	smp_wmb();
+	list_del_rcu(&xprt->xprt_switch);
+}
+
+/**
+ * rpc_xprt_switch_remove_xprt - Removes an rpc_xprt from a rpc_xprt_switch
+ * @xps: pointer to struct rpc_xprt_switch
+ * @xprt: pointer to struct rpc_xprt
+ *
+ * Removes xprt from the list of struct rpc_xprt in xps.
+ */
+void rpc_xprt_switch_remove_xprt(struct rpc_xprt_switch *xps,
+		struct rpc_xprt *xprt)
+{
+	spin_lock(&xps->xps_lock);
+	xprt_switch_remove_xprt_locked(xps, xprt);
+	spin_unlock(&xps->xps_lock);
+	xprt_put(xprt);
+}
+
+/**
+ * xprt_switch_alloc - Allocate a new struct rpc_xprt_switch
+ * @xprt: pointer to struct rpc_xprt
+ * @gfp_flags: allocation flags
+ *
+ * On success, returns an initialised struct rpc_xprt_switch, containing
+ * the entry xprt. Returns NULL on failure.
+ */
+struct rpc_xprt_switch *xprt_switch_alloc(struct rpc_xprt *xprt,
+		gfp_t gfp_flags)
+{
+	struct rpc_xprt_switch *xps;
+
+	xps = kmalloc(sizeof(*xps), gfp_flags);
+	if (xps != NULL) {
+		spin_lock_init(&xps->xps_lock);
+		kref_init(&xps->xps_kref);
+		xps->xps_nxprts = 0;
+		INIT_LIST_HEAD(&xps->xps_xprt_list);
+		xps->xps_iter_ops = &rpc_xprt_iter_singular;
+		xprt_switch_add_xprt_locked(xps, xprt);
+	}
+
+	return xps;
+}
+
+static void xprt_switch_free_entries(struct rpc_xprt_switch *xps)
+{
+	spin_lock(&xps->xps_lock);
+	while (!list_empty(&xps->xps_xprt_list)) {
+		struct rpc_xprt *xprt;
+
+		xprt = list_first_entry(&xps->xps_xprt_list,
+				struct rpc_xprt, xprt_switch);
+		xprt_switch_remove_xprt_locked(xps, xprt);
+		spin_unlock(&xps->xps_lock);
+		xprt_put(xprt);
+		spin_lock(&xps->xps_lock);
+	}
+	spin_unlock(&xps->xps_lock);
+}
+
+static void xprt_switch_free(struct kref *kref)
+{
+	struct rpc_xprt_switch *xps = container_of(kref,
+			struct rpc_xprt_switch, xps_kref);
+
+	xprt_switch_free_entries(xps);
+	kfree_rcu(xps, xps_rcu);
+}
+
+/**
+ * xprt_switch_get - Return a reference to a rpc_xprt_switch
+ * @xps: pointer to struct rpc_xprt_switch
+ *
+ * Returns a reference to xps unless the refcount is already zero.
+ */
+struct rpc_xprt_switch *xprt_switch_get(struct rpc_xprt_switch *xps)
+{
+	if (xps != NULL && kref_get_unless_zero(&xps->xps_kref))
+		return xps;
+	return NULL;
+}
+
+/**
+ * xprt_switch_put - Release a reference to a rpc_xprt_switch
+ * @xps: pointer to struct rpc_xprt_switch
+ *
+ * Release the reference to xps, and free it once the refcount is zero.
+ */
+void xprt_switch_put(struct rpc_xprt_switch *xps)
+{
+	if (xps != NULL)
+		kref_put(&xps->xps_kref, xprt_switch_free);
+}
+
+/**
+ * rpc_xprt_switch_set_roundrobin - Set a round-robin policy on rpc_xprt_switch
+ * @xps: pointer to struct rpc_xprt_switch
+ *
+ * Sets a round-robin default policy for iterators acting on xps.
+ */
+void rpc_xprt_switch_set_roundrobin(struct rpc_xprt_switch *xps)
+{
+	if (READ_ONCE(xps->xps_iter_ops) != &rpc_xprt_iter_roundrobin)
+		WRITE_ONCE(xps->xps_iter_ops, &rpc_xprt_iter_roundrobin);
+}
+
+static
+const struct rpc_xprt_iter_ops *xprt_iter_ops(const struct rpc_xprt_iter *xpi)
+{
+	if (xpi->xpi_ops != NULL)
+		return xpi->xpi_ops;
+	return rcu_dereference(xpi->xpi_xpswitch)->xps_iter_ops;
+}
+
+static
+void xprt_iter_no_rewind(struct rpc_xprt_iter *xpi)
+{
+}
+
+static
+void xprt_iter_default_rewind(struct rpc_xprt_iter *xpi)
+{
+	WRITE_ONCE(xpi->xpi_cursor, NULL);
+}
+
+static
+struct rpc_xprt *xprt_switch_find_first_entry(struct list_head *head)
+{
+	return list_first_or_null_rcu(head, struct rpc_xprt, xprt_switch);
+}
+
+static
+struct rpc_xprt *xprt_iter_first_entry(struct rpc_xprt_iter *xpi)
+{
+	struct rpc_xprt_switch *xps = rcu_dereference(xpi->xpi_xpswitch);
+
+	if (xps == NULL)
+		return NULL;
+	return xprt_switch_find_first_entry(&xps->xps_xprt_list);
+}
+
+static
+struct rpc_xprt *xprt_switch_find_current_entry(struct list_head *head,
+		const struct rpc_xprt *cur)
+{
+	struct rpc_xprt *pos;
+
+	list_for_each_entry_rcu(pos, head, xprt_switch) {
+		if (cur == pos)
+			return pos;
+	}
+	return NULL;
+}
+
+static
+struct rpc_xprt *xprt_iter_current_entry(struct rpc_xprt_iter *xpi)
+{
+	struct rpc_xprt_switch *xps = rcu_dereference(xpi->xpi_xpswitch);
+	struct list_head *head;
+
+	if (xps == NULL)
+		return NULL;
+	head = &xps->xps_xprt_list;
+	if (xpi->xpi_cursor == NULL || xps->xps_nxprts < 2)
+		return xprt_switch_find_first_entry(head);
+	return xprt_switch_find_current_entry(head, xpi->xpi_cursor);
+}
+
+static
+struct rpc_xprt *xprt_switch_find_next_entry(struct list_head *head,
+		const struct rpc_xprt *cur)
+{
+	struct rpc_xprt *pos, *prev = NULL;
+
+	list_for_each_entry_rcu(pos, head, xprt_switch) {
+		if (cur == prev)
+			return pos;
+		prev = pos;
+	}
+	return NULL;
+}
+
+static
+struct rpc_xprt *xprt_switch_set_next_cursor(struct list_head *head,
+		struct rpc_xprt **cursor,
+		xprt_switch_find_xprt_t find_next)
+{
+	struct rpc_xprt *cur, *pos, *old;
+
+	cur = READ_ONCE(*cursor);
+	for (;;) {
+		old = cur;
+		pos = find_next(head, old);
+		if (pos == NULL)
+			break;
+		cur = cmpxchg_relaxed(cursor, old, pos);
+		if (cur == old)
+			break;
+	}
+	return pos;
+}
+
+static
+struct rpc_xprt *xprt_iter_next_entry_multiple(struct rpc_xprt_iter *xpi,
+		xprt_switch_find_xprt_t find_next)
+{
+	struct rpc_xprt_switch *xps = rcu_dereference(xpi->xpi_xpswitch);
+	struct list_head *head;
+
+	if (xps == NULL)
+		return NULL;
+	head = &xps->xps_xprt_list;
+	if (xps->xps_nxprts < 2)
+		return xprt_switch_find_first_entry(head);
+	return xprt_switch_set_next_cursor(head, &xpi->xpi_cursor, find_next);
+}
+
+static
+struct rpc_xprt *xprt_switch_find_next_entry_roundrobin(struct list_head *head,
+		const struct rpc_xprt *cur)
+{
+	struct rpc_xprt *ret;
+
+	ret = xprt_switch_find_next_entry(head, cur);
+	if (ret != NULL)
+		return ret;
+	return xprt_switch_find_first_entry(head);
+}
+
+static
+struct rpc_xprt *xprt_iter_next_entry_roundrobin(struct rpc_xprt_iter *xpi)
+{
+	return xprt_iter_next_entry_multiple(xpi,
+			xprt_switch_find_next_entry_roundrobin);
+}
+
+static
+struct rpc_xprt *xprt_iter_next_entry_all(struct rpc_xprt_iter *xpi)
+{
+	return xprt_iter_next_entry_multiple(xpi, xprt_switch_find_next_entry);
+}
+
+/*
+ * xprt_iter_rewind - Resets the xprt iterator
+ * @xpi: pointer to rpc_xprt_iter
+ *
+ * Resets xpi to ensure that it points to the first entry in the list
+ * of transports.
+ */
+static
+void xprt_iter_rewind(struct rpc_xprt_iter *xpi)
+{
+	rcu_read_lock();
+	xprt_iter_ops(xpi)->xpi_rewind(xpi);
+	rcu_read_unlock();
+}
+
+static void __xprt_iter_init(struct rpc_xprt_iter *xpi,
+		struct rpc_xprt_switch *xps,
+		const struct rpc_xprt_iter_ops *ops)
+{
+	rcu_assign_pointer(xpi->xpi_xpswitch, xprt_switch_get(xps));
+	xpi->xpi_cursor = NULL;
+	xpi->xpi_ops = ops;
+}
+
+/**
+ * xprt_iter_init - Initialise an xprt iterator
+ * @xpi: pointer to rpc_xprt_iter
+ * @xps: pointer to rpc_xprt_switch
+ *
+ * Initialises the iterator to use the default iterator ops
+ * as set in xps. This function is mainly intended for internal
+ * use in the rpc_client.
+ */
+void xprt_iter_init(struct rpc_xprt_iter *xpi,
+		struct rpc_xprt_switch *xps)
+{
+	__xprt_iter_init(xpi, xps, NULL);
+}
+
+/**
+ * xprt_iter_init_listall - Initialise an xprt iterator
+ * @xpi: pointer to rpc_xprt_iter
+ * @xps: pointer to rpc_xprt_switch
+ *
+ * Initialises the iterator to iterate once through the entire list
+ * of entries in xps.
+ */
+void xprt_iter_init_listall(struct rpc_xprt_iter *xpi,
+		struct rpc_xprt_switch *xps)
+{
+	__xprt_iter_init(xpi, xps, &rpc_xprt_iter_listall);
+}
+
+/**
+ * xprt_iter_xchg_switch - Atomically swap out the rpc_xprt_switch
+ * @xpi: pointer to rpc_xprt_iter
+ * @xps: pointer to a new rpc_xprt_switch or NULL
+ *
+ * Swaps out the existing xpi->xpi_xpswitch with a new value.
+ */
+struct rpc_xprt_switch *xprt_iter_xchg_switch(struct rpc_xprt_iter *xpi,
+		struct rpc_xprt_switch *newswitch)
+{
+	struct rpc_xprt_switch __rcu *oldswitch;
+
+	/* Atomically swap out the old xpswitch */
+	oldswitch = xchg(&xpi->xpi_xpswitch, RCU_INITIALIZER(newswitch));
+	if (newswitch != NULL)
+		xprt_iter_rewind(xpi);
+	return rcu_dereference_protected(oldswitch, true);
+}
+
+/**
+ * xprt_iter_destroy - Destroys the xprt iterator
+ * @xpi pointer to rpc_xprt_iter
+ */
+void xprt_iter_destroy(struct rpc_xprt_iter *xpi)
+{
+	xprt_switch_put(xprt_iter_xchg_switch(xpi, NULL));
+}
+
+/**
+ * xprt_iter_xprt - Returns the rpc_xprt pointed to by the cursor
+ * @xpi: pointer to rpc_xprt_iter
+ *
+ * Returns a pointer to the struct rpc_xprt that is currently
+ * pointed to by the cursor.
+ * Caller must be holding rcu_read_lock().
+ */
+struct rpc_xprt *xprt_iter_xprt(struct rpc_xprt_iter *xpi)
+{
+	WARN_ON_ONCE(!rcu_read_lock_held());
+	return xprt_iter_ops(xpi)->xpi_xprt(xpi);
+}
+
+static
+struct rpc_xprt *xprt_iter_get_helper(struct rpc_xprt_iter *xpi,
+		struct rpc_xprt *(*fn)(struct rpc_xprt_iter *))
+{
+	struct rpc_xprt *ret;
+
+	do {
+		ret = fn(xpi);
+		if (ret == NULL)
+			break;
+		ret = xprt_get(ret);
+	} while (ret == NULL);
+	return ret;
+}
+
+/**
+ * xprt_iter_get_xprt - Returns the rpc_xprt pointed to by the cursor
+ * @xpi: pointer to rpc_xprt_iter
+ *
+ * Returns a reference to the struct rpc_xprt that is currently
+ * pointed to by the cursor.
+ */
+struct rpc_xprt *xprt_iter_get_xprt(struct rpc_xprt_iter *xpi)
+{
+	struct rpc_xprt *xprt;
+
+	rcu_read_lock();
+	xprt = xprt_iter_get_helper(xpi, xprt_iter_ops(xpi)->xpi_xprt);
+	rcu_read_unlock();
+	return xprt;
+}
+
+/**
+ * xprt_iter_get_next - Returns the next rpc_xprt following the cursor
+ * @xpi: pointer to rpc_xprt_iter
+ *
+ * Returns a reference to the struct rpc_xprt that immediately follows the
+ * entry pointed to by the cursor.
+ */
+struct rpc_xprt *xprt_iter_get_next(struct rpc_xprt_iter *xpi)
+{
+	struct rpc_xprt *xprt;
+
+	rcu_read_lock();
+	xprt = xprt_iter_get_helper(xpi, xprt_iter_ops(xpi)->xpi_next);
+	rcu_read_unlock();
+	return xprt;
+}
+
+/* Policy for always returning the first entry in the rpc_xprt_switch */
+static
+const struct rpc_xprt_iter_ops rpc_xprt_iter_singular = {
+	.xpi_rewind = xprt_iter_no_rewind,
+	.xpi_xprt = xprt_iter_first_entry,
+	.xpi_next = xprt_iter_first_entry,
+};
+
+/* Policy for round-robin iteration of entries in the rpc_xprt_switch */
+static
+const struct rpc_xprt_iter_ops rpc_xprt_iter_roundrobin = {
+	.xpi_rewind = xprt_iter_default_rewind,
+	.xpi_xprt = xprt_iter_current_entry,
+	.xpi_next = xprt_iter_next_entry_roundrobin,
+};
+
+/* Policy for once-through iteration of entries in the rpc_xprt_switch */
+static
+const struct rpc_xprt_iter_ops rpc_xprt_iter_listall = {
+	.xpi_rewind = xprt_iter_default_rewind,
+	.xpi_xprt = xprt_iter_current_entry,
+	.xpi_next = xprt_iter_next_entry_all,
+};
diff --git a/net/sunrpc/xprtrdma/fmr_ops.c b/net/sunrpc/xprtrdma/fmr_ops.c
index c14f3a4bff68..b289e106540b 100644
--- a/net/sunrpc/xprtrdma/fmr_ops.c
+++ b/net/sunrpc/xprtrdma/fmr_ops.c
@@ -80,13 +80,13 @@ fmr_op_init(struct rpcrdma_xprt *r_xprt)
 		if (!r)
 			goto out;
 
-		r->r.fmr.physaddrs = kmalloc(RPCRDMA_MAX_FMR_SGES *
-					     sizeof(u64), GFP_KERNEL);
-		if (!r->r.fmr.physaddrs)
+		r->fmr.physaddrs = kmalloc(RPCRDMA_MAX_FMR_SGES *
+					   sizeof(u64), GFP_KERNEL);
+		if (!r->fmr.physaddrs)
 			goto out_free;
 
-		r->r.fmr.fmr = ib_alloc_fmr(pd, mr_access_flags, &fmr_attr);
-		if (IS_ERR(r->r.fmr.fmr))
+		r->fmr.fmr = ib_alloc_fmr(pd, mr_access_flags, &fmr_attr);
+		if (IS_ERR(r->fmr.fmr))
 			goto out_fmr_err;
 
 		list_add(&r->mw_list, &buf->rb_mws);
@@ -95,9 +95,9 @@ fmr_op_init(struct rpcrdma_xprt *r_xprt)
 	return 0;
 
 out_fmr_err:
-	rc = PTR_ERR(r->r.fmr.fmr);
+	rc = PTR_ERR(r->fmr.fmr);
 	dprintk("RPC:       %s: ib_alloc_fmr status %i\n", __func__, rc);
-	kfree(r->r.fmr.physaddrs);
+	kfree(r->fmr.physaddrs);
 out_free:
 	kfree(r);
 out:
@@ -109,7 +109,7 @@ __fmr_unmap(struct rpcrdma_mw *r)
 {
 	LIST_HEAD(l);
 
-	list_add(&r->r.fmr.fmr->list, &l);
+	list_add(&r->fmr.fmr->list, &l);
 	return ib_unmap_fmr(&l);
 }
 
@@ -148,7 +148,7 @@ fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
 		nsegs = RPCRDMA_MAX_FMR_SGES;
 	for (i = 0; i < nsegs;) {
 		rpcrdma_map_one(device, seg, direction);
-		mw->r.fmr.physaddrs[i] = seg->mr_dma;
+		mw->fmr.physaddrs[i] = seg->mr_dma;
 		len += seg->mr_len;
 		++seg;
 		++i;
@@ -158,13 +158,13 @@ fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
 			break;
 	}
 
-	rc = ib_map_phys_fmr(mw->r.fmr.fmr, mw->r.fmr.physaddrs,
+	rc = ib_map_phys_fmr(mw->fmr.fmr, mw->fmr.physaddrs,
 			     i, seg1->mr_dma);
 	if (rc)
 		goto out_maperr;
 
 	seg1->rl_mw = mw;
-	seg1->mr_rkey = mw->r.fmr.fmr->rkey;
+	seg1->mr_rkey = mw->fmr.fmr->rkey;
 	seg1->mr_base = seg1->mr_dma + pageoff;
 	seg1->mr_nsegs = i;
 	seg1->mr_len = len;
@@ -219,7 +219,7 @@ fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
 		seg = &req->rl_segments[i];
 		mw = seg->rl_mw;
 
-		list_add(&mw->r.fmr.fmr->list, &unmap_list);
+		list_add(&mw->fmr.fmr->list, &unmap_list);
 
 		i += seg->mr_nsegs;
 	}
@@ -281,9 +281,9 @@ fmr_op_destroy(struct rpcrdma_buffer *buf)
 	while (!list_empty(&buf->rb_all)) {
 		r = list_entry(buf->rb_all.next, struct rpcrdma_mw, mw_all);
 		list_del(&r->mw_all);
-		kfree(r->r.fmr.physaddrs);
+		kfree(r->fmr.physaddrs);
 
-		rc = ib_dealloc_fmr(r->r.fmr.fmr);
+		rc = ib_dealloc_fmr(r->fmr.fmr);
 		if (rc)
 			dprintk("RPC:       %s: ib_dealloc_fmr failed %i\n",
 				__func__, rc);
diff --git a/net/sunrpc/xprtrdma/frwr_ops.c b/net/sunrpc/xprtrdma/frwr_ops.c
index e16567389e28..c250924a9fd3 100644
--- a/net/sunrpc/xprtrdma/frwr_ops.c
+++ b/net/sunrpc/xprtrdma/frwr_ops.c
@@ -109,20 +109,20 @@ static void
 __frwr_recovery_worker(struct work_struct *work)
 {
 	struct rpcrdma_mw *r = container_of(work, struct rpcrdma_mw,
-					    r.frmr.fr_work);
-	struct rpcrdma_xprt *r_xprt = r->r.frmr.fr_xprt;
+					    frmr.fr_work);
+	struct rpcrdma_xprt *r_xprt = r->frmr.fr_xprt;
 	unsigned int depth = r_xprt->rx_ia.ri_max_frmr_depth;
 	struct ib_pd *pd = r_xprt->rx_ia.ri_pd;
 
-	if (ib_dereg_mr(r->r.frmr.fr_mr))
+	if (ib_dereg_mr(r->frmr.fr_mr))
 		goto out_fail;
 
-	r->r.frmr.fr_mr = ib_alloc_mr(pd, IB_MR_TYPE_MEM_REG, depth);
-	if (IS_ERR(r->r.frmr.fr_mr))
+	r->frmr.fr_mr = ib_alloc_mr(pd, IB_MR_TYPE_MEM_REG, depth);
+	if (IS_ERR(r->frmr.fr_mr))
 		goto out_fail;
 
 	dprintk("RPC:       %s: recovered FRMR %p\n", __func__, r);
-	r->r.frmr.fr_state = FRMR_IS_INVALID;
+	r->frmr.fr_state = FRMR_IS_INVALID;
 	rpcrdma_put_mw(r_xprt, r);
 	return;
 
@@ -137,15 +137,15 @@ out_fail:
 static void
 __frwr_queue_recovery(struct rpcrdma_mw *r)
 {
-	INIT_WORK(&r->r.frmr.fr_work, __frwr_recovery_worker);
-	queue_work(frwr_recovery_wq, &r->r.frmr.fr_work);
+	INIT_WORK(&r->frmr.fr_work, __frwr_recovery_worker);
+	queue_work(frwr_recovery_wq, &r->frmr.fr_work);
 }
 
 static int
 __frwr_init(struct rpcrdma_mw *r, struct ib_pd *pd, struct ib_device *device,
 	    unsigned int depth)
 {
-	struct rpcrdma_frmr *f = &r->r.frmr;
+	struct rpcrdma_frmr *f = &r->frmr;
 	int rc;
 
 	f->fr_mr = ib_alloc_mr(pd, IB_MR_TYPE_MEM_REG, depth);
@@ -158,6 +158,8 @@ __frwr_init(struct rpcrdma_mw *r, struct ib_pd *pd, struct ib_device *device,
 
 	sg_init_table(f->sg, depth);
 
+	init_completion(&f->fr_linv_done);
+
 	return 0;
 
 out_mr_err:
@@ -179,11 +181,11 @@ __frwr_release(struct rpcrdma_mw *r)
 {
 	int rc;
 
-	rc = ib_dereg_mr(r->r.frmr.fr_mr);
+	rc = ib_dereg_mr(r->frmr.fr_mr);
 	if (rc)
 		dprintk("RPC:       %s: ib_dereg_mr status %i\n",
 			__func__, rc);
-	kfree(r->r.frmr.sg);
+	kfree(r->frmr.sg);
 }
 
 static int
@@ -244,39 +246,76 @@ frwr_op_maxpages(struct rpcrdma_xprt *r_xprt)
 		     rpcrdma_max_segments(r_xprt) * ia->ri_max_frmr_depth);
 }
 
-/* If FAST_REG or LOCAL_INV failed, indicate the frmr needs
- * to be reset.
+static void
+__frwr_sendcompletion_flush(struct ib_wc *wc, struct rpcrdma_frmr *frmr,
+			    const char *wr)
+{
+	frmr->fr_state = FRMR_IS_STALE;
+	if (wc->status != IB_WC_WR_FLUSH_ERR)
+		pr_err("rpcrdma: %s: %s (%u/0x%x)\n",
+		       wr, ib_wc_status_msg(wc->status),
+		       wc->status, wc->vendor_err);
+}
+
+/**
+ * frwr_wc_fastreg - Invoked by RDMA provider for each polled FastReg WC
+ * @cq:	completion queue (ignored)
+ * @wc:	completed WR
  *
- * WARNING: Only wr_id and status are reliable at this point
  */
 static void
-__frwr_sendcompletion_flush(struct ib_wc *wc, struct rpcrdma_mw *r)
+frwr_wc_fastreg(struct ib_cq *cq, struct ib_wc *wc)
 {
-	if (likely(wc->status == IB_WC_SUCCESS))
-		return;
-
-	/* WARNING: Only wr_id and status are reliable at this point */
-	r = (struct rpcrdma_mw *)(unsigned long)wc->wr_id;
-	if (wc->status == IB_WC_WR_FLUSH_ERR)
-		dprintk("RPC:       %s: frmr %p flushed\n", __func__, r);
-	else
-		pr_warn("RPC:       %s: frmr %p error, status %s (%d)\n",
-			__func__, r, ib_wc_status_msg(wc->status), wc->status);
+	struct rpcrdma_frmr *frmr;
+	struct ib_cqe *cqe;
 
-	r->r.frmr.fr_state = FRMR_IS_STALE;
+	/* WARNING: Only wr_cqe and status are reliable at this point */
+	if (wc->status != IB_WC_SUCCESS) {
+		cqe = wc->wr_cqe;
+		frmr = container_of(cqe, struct rpcrdma_frmr, fr_cqe);
+		__frwr_sendcompletion_flush(wc, frmr, "fastreg");
+	}
 }
 
+/**
+ * frwr_wc_localinv - Invoked by RDMA provider for each polled LocalInv WC
+ * @cq:	completion queue (ignored)
+ * @wc:	completed WR
+ *
+ */
 static void
-frwr_sendcompletion(struct ib_wc *wc)
+frwr_wc_localinv(struct ib_cq *cq, struct ib_wc *wc)
 {
-	struct rpcrdma_mw *r = (struct rpcrdma_mw *)(unsigned long)wc->wr_id;
-	struct rpcrdma_frmr *f = &r->r.frmr;
+	struct rpcrdma_frmr *frmr;
+	struct ib_cqe *cqe;
 
-	if (unlikely(wc->status != IB_WC_SUCCESS))
-		__frwr_sendcompletion_flush(wc, r);
+	/* WARNING: Only wr_cqe and status are reliable at this point */
+	if (wc->status != IB_WC_SUCCESS) {
+		cqe = wc->wr_cqe;
+		frmr = container_of(cqe, struct rpcrdma_frmr, fr_cqe);
+		__frwr_sendcompletion_flush(wc, frmr, "localinv");
+	}
+}
 
-	if (f->fr_waiter)
-		complete(&f->fr_linv_done);
+/**
+ * frwr_wc_localinv - Invoked by RDMA provider for each polled LocalInv WC
+ * @cq:	completion queue (ignored)
+ * @wc:	completed WR
+ *
+ * Awaken anyone waiting for an MR to finish being fenced.
+ */
+static void
+frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
+{
+	struct rpcrdma_frmr *frmr;
+	struct ib_cqe *cqe;
+
+	/* WARNING: Only wr_cqe and status are reliable at this point */
+	cqe = wc->wr_cqe;
+	frmr = container_of(cqe, struct rpcrdma_frmr, fr_cqe);
+	if (wc->status != IB_WC_SUCCESS)
+		__frwr_sendcompletion_flush(wc, frmr, "localinv");
+	complete_all(&frmr->fr_linv_done);
 }
 
 static int
@@ -313,8 +352,7 @@ frwr_op_init(struct rpcrdma_xprt *r_xprt)
 
 		list_add(&r->mw_list, &buf->rb_mws);
 		list_add(&r->mw_all, &buf->rb_all);
-		r->mw_sendcompletion = frwr_sendcompletion;
-		r->r.frmr.fr_xprt = r_xprt;
+		r->frmr.fr_xprt = r_xprt;
 	}
 
 	return 0;
@@ -347,10 +385,9 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
 		mw = rpcrdma_get_mw(r_xprt);
 		if (!mw)
 			return -ENOMEM;
-	} while (mw->r.frmr.fr_state != FRMR_IS_INVALID);
-	frmr = &mw->r.frmr;
+	} while (mw->frmr.fr_state != FRMR_IS_INVALID);
+	frmr = &mw->frmr;
 	frmr->fr_state = FRMR_IS_VALID;
-	frmr->fr_waiter = false;
 	mr = frmr->fr_mr;
 	reg_wr = &frmr->fr_regwr;
 
@@ -400,7 +437,8 @@ frwr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
 
 	reg_wr->wr.next = NULL;
 	reg_wr->wr.opcode = IB_WR_REG_MR;
-	reg_wr->wr.wr_id = (uintptr_t)mw;
+	frmr->fr_cqe.done = frwr_wc_fastreg;
+	reg_wr->wr.wr_cqe = &frmr->fr_cqe;
 	reg_wr->wr.num_sge = 0;
 	reg_wr->wr.send_flags = 0;
 	reg_wr->mr = mr;
@@ -434,15 +472,15 @@ static struct ib_send_wr *
 __frwr_prepare_linv_wr(struct rpcrdma_mr_seg *seg)
 {
 	struct rpcrdma_mw *mw = seg->rl_mw;
-	struct rpcrdma_frmr *f = &mw->r.frmr;
+	struct rpcrdma_frmr *f = &mw->frmr;
 	struct ib_send_wr *invalidate_wr;
 
-	f->fr_waiter = false;
 	f->fr_state = FRMR_IS_INVALID;
 	invalidate_wr = &f->fr_invwr;
 
 	memset(invalidate_wr, 0, sizeof(*invalidate_wr));
-	invalidate_wr->wr_id = (unsigned long)(void *)mw;
+	f->fr_cqe.done = frwr_wc_localinv;
+	invalidate_wr->wr_cqe = &f->fr_cqe;
 	invalidate_wr->opcode = IB_WR_LOCAL_INV;
 	invalidate_wr->ex.invalidate_rkey = f->fr_mr->rkey;
 
@@ -455,7 +493,7 @@ __frwr_dma_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
 {
 	struct ib_device *device = r_xprt->rx_ia.ri_device;
 	struct rpcrdma_mw *mw = seg->rl_mw;
-	struct rpcrdma_frmr *f = &mw->r.frmr;
+	struct rpcrdma_frmr *f = &mw->frmr;
 
 	seg->rl_mw = NULL;
 
@@ -504,15 +542,15 @@ frwr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
 
 		i += seg->mr_nsegs;
 	}
-	f = &seg->rl_mw->r.frmr;
+	f = &seg->rl_mw->frmr;
 
 	/* Strong send queue ordering guarantees that when the
 	 * last WR in the chain completes, all WRs in the chain
 	 * are complete.
 	 */
 	f->fr_invwr.send_flags = IB_SEND_SIGNALED;
-	f->fr_waiter = true;
-	init_completion(&f->fr_linv_done);
+	f->fr_cqe.done = frwr_wc_localinv_wake;
+	reinit_completion(&f->fr_linv_done);
 	INIT_CQCOUNT(&r_xprt->rx_ep);
 
 	/* Transport disconnect drains the receive CQ before it
@@ -520,14 +558,18 @@ frwr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
 	 * unless ri_id->qp is a valid pointer.
 	 */
 	rc = ib_post_send(ia->ri_id->qp, invalidate_wrs, &bad_wr);
-	if (rc)
+	if (rc) {
 		pr_warn("%s: ib_post_send failed %i\n", __func__, rc);
+		rdma_disconnect(ia->ri_id);
+		goto unmap;
+	}
 
 	wait_for_completion(&f->fr_linv_done);
 
 	/* ORDER: Now DMA unmap all of the req's MRs, and return
 	 * them to the free MW list.
 	 */
+unmap:
 	for (i = 0, nchunks = req->rl_nchunks; nchunks; nchunks--) {
 		seg = &req->rl_segments[i];
 
@@ -549,7 +591,7 @@ frwr_op_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
 	struct rpcrdma_mr_seg *seg1 = seg;
 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
 	struct rpcrdma_mw *mw = seg1->rl_mw;
-	struct rpcrdma_frmr *frmr = &mw->r.frmr;
+	struct rpcrdma_frmr *frmr = &mw->frmr;
 	struct ib_send_wr *invalidate_wr, *bad_wr;
 	int rc, nsegs = seg->mr_nsegs;
 
@@ -557,10 +599,11 @@ frwr_op_unmap(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg)
 
 	seg1->rl_mw = NULL;
 	frmr->fr_state = FRMR_IS_INVALID;
-	invalidate_wr = &mw->r.frmr.fr_invwr;
+	invalidate_wr = &mw->frmr.fr_invwr;
 
 	memset(invalidate_wr, 0, sizeof(*invalidate_wr));
-	invalidate_wr->wr_id = (uintptr_t)mw;
+	frmr->fr_cqe.done = frwr_wc_localinv;
+	invalidate_wr->wr_cqe = &frmr->fr_cqe;
 	invalidate_wr->opcode = IB_WR_LOCAL_INV;
 	invalidate_wr->ex.invalidate_rkey = frmr->fr_mr->rkey;
 	DECR_CQCOUNT(&r_xprt->rx_ep);
diff --git a/net/sunrpc/xprtrdma/physical_ops.c b/net/sunrpc/xprtrdma/physical_ops.c
index dbb302ecf590..481b9b6f4a15 100644
--- a/net/sunrpc/xprtrdma/physical_ops.c
+++ b/net/sunrpc/xprtrdma/physical_ops.c
@@ -68,7 +68,6 @@ physical_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
 	rpcrdma_map_one(ia->ri_device, seg, rpcrdma_data_dir(writing));
 	seg->mr_rkey = ia->ri_dma_mr->rkey;
 	seg->mr_base = seg->mr_dma;
-	seg->mr_nsegs = 1;
 	return 1;
 }
 
diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 0f28f2d743ed..888823bb6dae 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -132,6 +132,33 @@ rpcrdma_tail_pullup(struct xdr_buf *buf)
 	return tlen;
 }
 
+/* Split "vec" on page boundaries into segments. FMR registers pages,
+ * not a byte range. Other modes coalesce these segments into a single
+ * MR when they can.
+ */
+static int
+rpcrdma_convert_kvec(struct kvec *vec, struct rpcrdma_mr_seg *seg,
+		     int n, int nsegs)
+{
+	size_t page_offset;
+	u32 remaining;
+	char *base;
+
+	base = vec->iov_base;
+	page_offset = offset_in_page(base);
+	remaining = vec->iov_len;
+	while (remaining && n < nsegs) {
+		seg[n].mr_page = NULL;
+		seg[n].mr_offset = base;
+		seg[n].mr_len = min_t(u32, PAGE_SIZE - page_offset, remaining);
+		remaining -= seg[n].mr_len;
+		base += seg[n].mr_len;
+		++n;
+		page_offset = 0;
+	}
+	return n;
+}
+
 /*
  * Chunk assembly from upper layer xdr_buf.
  *
@@ -150,11 +177,10 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
 	int page_base;
 	struct page **ppages;
 
-	if (pos == 0 && xdrbuf->head[0].iov_len) {
-		seg[n].mr_page = NULL;
-		seg[n].mr_offset = xdrbuf->head[0].iov_base;
-		seg[n].mr_len = xdrbuf->head[0].iov_len;
-		++n;
+	if (pos == 0) {
+		n = rpcrdma_convert_kvec(&xdrbuf->head[0], seg, n, nsegs);
+		if (n == nsegs)
+			return -EIO;
 	}
 
 	len = xdrbuf->page_len;
@@ -192,13 +218,9 @@ rpcrdma_convert_iovs(struct xdr_buf *xdrbuf, unsigned int pos,
 		 * xdr pad bytes, saving the server an RDMA operation. */
 		if (xdrbuf->tail[0].iov_len < 4 && xprt_rdma_pad_optimize)
 			return n;
+		n = rpcrdma_convert_kvec(&xdrbuf->tail[0], seg, n, nsegs);
 		if (n == nsegs)
-			/* Tail remains, but we're out of segments */
 			return -EIO;
-		seg[n].mr_page = NULL;
-		seg[n].mr_offset = xdrbuf->tail[0].iov_base;
-		seg[n].mr_len = xdrbuf->tail[0].iov_len;
-		++n;
 	}
 
 	return n;
@@ -773,20 +795,17 @@ rpcrdma_reply_handler(struct rpcrdma_rep *rep)
 	struct rpcrdma_xprt *r_xprt = rep->rr_rxprt;
 	struct rpc_xprt *xprt = &r_xprt->rx_xprt;
 	__be32 *iptr;
-	int rdmalen, status;
+	int rdmalen, status, rmerr;
 	unsigned long cwnd;
-	u32 credits;
 
 	dprintk("RPC:       %s: incoming rep %p\n", __func__, rep);
 
 	if (rep->rr_len == RPCRDMA_BAD_LEN)
 		goto out_badstatus;
-	if (rep->rr_len < RPCRDMA_HDRLEN_MIN)
+	if (rep->rr_len < RPCRDMA_HDRLEN_ERR)
 		goto out_shortreply;
 
 	headerp = rdmab_to_msg(rep->rr_rdmabuf);
-	if (headerp->rm_vers != rpcrdma_version)
-		goto out_badversion;
 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
 	if (rpcrdma_is_bcall(headerp))
 		goto out_bcall;
@@ -809,15 +828,16 @@ rpcrdma_reply_handler(struct rpcrdma_rep *rep)
 	 */
 	list_del_init(&rqst->rq_list);
 	spin_unlock_bh(&xprt->transport_lock);
-	dprintk("RPC:       %s: reply 0x%p completes request 0x%p\n"
-		"                   RPC request 0x%p xid 0x%08x\n",
-			__func__, rep, req, rqst,
-			be32_to_cpu(headerp->rm_xid));
+	dprintk("RPC:       %s: reply %p completes request %p (xid 0x%08x)\n",
+		__func__, rep, req, be32_to_cpu(headerp->rm_xid));
 
 	/* from here on, the reply is no longer an orphan */
 	req->rl_reply = rep;
 	xprt->reestablish_timeout = 0;
 
+	if (headerp->rm_vers != rpcrdma_version)
+		goto out_badversion;
+
 	/* check for expected message types */
 	/* The order of some of these tests is important. */
 	switch (headerp->rm_type) {
@@ -878,6 +898,9 @@ rpcrdma_reply_handler(struct rpcrdma_rep *rep)
 		status = rdmalen;
 		break;
 
+	case rdma_error:
+		goto out_rdmaerr;
+
 badheader:
 	default:
 		dprintk("%s: invalid rpcrdma reply header (type %d):"
@@ -893,6 +916,7 @@ badheader:
 		break;
 	}
 
+out:
 	/* Invalidate and flush the data payloads before waking the
 	 * waiting application. This guarantees the memory region is
 	 * properly fenced from the server before the application
@@ -903,15 +927,9 @@ badheader:
 	if (req->rl_nchunks)
 		r_xprt->rx_ia.ri_ops->ro_unmap_sync(r_xprt, req);
 
-	credits = be32_to_cpu(headerp->rm_credit);
-	if (credits == 0)
-		credits = 1;	/* don't deadlock */
-	else if (credits > r_xprt->rx_buf.rb_max_requests)
-		credits = r_xprt->rx_buf.rb_max_requests;
-
 	spin_lock_bh(&xprt->transport_lock);
 	cwnd = xprt->cwnd;
-	xprt->cwnd = credits << RPC_CWNDSHIFT;
+	xprt->cwnd = atomic_read(&r_xprt->rx_buf.rb_credits) << RPC_CWNDSHIFT;
 	if (xprt->cwnd > cwnd)
 		xprt_release_rqst_cong(rqst->rq_task);
 
@@ -935,13 +953,43 @@ out_bcall:
 	return;
 #endif
 
-out_shortreply:
-	dprintk("RPC:       %s: short/invalid reply\n", __func__);
-	goto repost;
-
+/* If the incoming reply terminated a pending RPC, the next
+ * RPC call will post a replacement receive buffer as it is
+ * being marshaled.
+ */
 out_badversion:
 	dprintk("RPC:       %s: invalid version %d\n",
 		__func__, be32_to_cpu(headerp->rm_vers));
+	status = -EIO;
+	r_xprt->rx_stats.bad_reply_count++;
+	goto out;
+
+out_rdmaerr:
+	rmerr = be32_to_cpu(headerp->rm_body.rm_error.rm_err);
+	switch (rmerr) {
+	case ERR_VERS:
+		pr_err("%s: server reports header version error (%u-%u)\n",
+		       __func__,
+		       be32_to_cpu(headerp->rm_body.rm_error.rm_vers_low),
+		       be32_to_cpu(headerp->rm_body.rm_error.rm_vers_high));
+		break;
+	case ERR_CHUNK:
+		pr_err("%s: server reports header decoding error\n",
+		       __func__);
+		break;
+	default:
+		pr_err("%s: server reports unknown error %d\n",
+		       __func__, rmerr);
+	}
+	status = -EREMOTEIO;
+	r_xprt->rx_stats.bad_reply_count++;
+	goto out;
+
+/* If no pending RPC transaction was matched, post a replacement
+ * receive buffer before returning.
+ */
+out_shortreply:
+	dprintk("RPC:       %s: short/invalid reply\n", __func__);
 	goto repost;
 
 out_nomatch:
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 878f1bfb1db9..f5ed9f982cd7 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -112,89 +112,65 @@ rpcrdma_qp_async_error_upcall(struct ib_event *event, void *context)
 	}
 }
 
+/**
+ * rpcrdma_wc_send - Invoked by RDMA provider for each polled Send WC
+ * @cq:	completion queue (ignored)
+ * @wc:	completed WR
+ *
+ */
 static void
-rpcrdma_cq_async_error_upcall(struct ib_event *event, void *context)
+rpcrdma_wc_send(struct ib_cq *cq, struct ib_wc *wc)
 {
-	struct rpcrdma_ep *ep = context;
-
-	pr_err("RPC:       %s: %s on device %s ep %p\n",
-	       __func__, 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);
-	}
+	/* WARNING: Only wr_cqe and status are reliable at this point */
+	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);
 }
 
 static void
-rpcrdma_sendcq_process_wc(struct ib_wc *wc)
+rpcrdma_receive_worker(struct work_struct *work)
 {
-	/* WARNING: Only wr_id and status are reliable at this point */
-	if (wc->wr_id == RPCRDMA_IGNORE_COMPLETION) {
-		if (wc->status != IB_WC_SUCCESS &&
-		    wc->status != IB_WC_WR_FLUSH_ERR)
-			pr_err("RPC:       %s: SEND: %s\n",
-			       __func__, ib_wc_status_msg(wc->status));
-	} else {
-		struct rpcrdma_mw *r;
+	struct rpcrdma_rep *rep =
+			container_of(work, struct rpcrdma_rep, rr_work);
 
-		r = (struct rpcrdma_mw *)(unsigned long)wc->wr_id;
-		r->mw_sendcompletion(wc);
-	}
+	rpcrdma_reply_handler(rep);
 }
 
-/* The common case is a single send completion is waiting. By
- * passing two WC entries to ib_poll_cq, a return code of 1
- * means there is exactly one WC waiting and no more. We don't
- * have to invoke ib_poll_cq again to know that the CQ has been
- * properly drained.
+/* Perform basic sanity checking to avoid using garbage
+ * to update the credit grant value.
  */
 static void
-rpcrdma_sendcq_poll(struct ib_cq *cq)
+rpcrdma_update_granted_credits(struct rpcrdma_rep *rep)
 {
-	struct ib_wc *pos, wcs[2];
-	int count, rc;
+	struct rpcrdma_msg *rmsgp = rdmab_to_msg(rep->rr_rdmabuf);
+	struct rpcrdma_buffer *buffer = &rep->rr_rxprt->rx_buf;
+	u32 credits;
 
-	do {
-		pos = wcs;
+	if (rep->rr_len < RPCRDMA_HDRLEN_ERR)
+		return;
 
-		rc = ib_poll_cq(cq, ARRAY_SIZE(wcs), pos);
-		if (rc < 0)
-			break;
+	credits = be32_to_cpu(rmsgp->rm_credit);
+	if (credits == 0)
+		credits = 1;	/* don't deadlock */
+	else if (credits > buffer->rb_max_requests)
+		credits = buffer->rb_max_requests;
 
-		count = rc;
-		while (count-- > 0)
-			rpcrdma_sendcq_process_wc(pos++);
-	} while (rc == ARRAY_SIZE(wcs));
-	return;
+	atomic_set(&buffer->rb_credits, credits);
 }
 
-/* Handle provider send completion upcalls.
+/**
+ * rpcrdma_receive_wc - Invoked by RDMA provider for each polled Receive WC
+ * @cq:	completion queue (ignored)
+ * @wc:	completed WR
+ *
  */
 static void
-rpcrdma_sendcq_upcall(struct ib_cq *cq, void *cq_context)
+rpcrdma_receive_wc(struct ib_cq *cq, struct ib_wc *wc)
 {
-	do {
-		rpcrdma_sendcq_poll(cq);
-	} while (ib_req_notify_cq(cq, IB_CQ_NEXT_COMP |
-				  IB_CQ_REPORT_MISSED_EVENTS) > 0);
-}
-
-static void
-rpcrdma_receive_worker(struct work_struct *work)
-{
-	struct rpcrdma_rep *rep =
-			container_of(work, struct rpcrdma_rep, rr_work);
-
-	rpcrdma_reply_handler(rep);
-}
-
-static void
-rpcrdma_recvcq_process_wc(struct ib_wc *wc)
-{
-	struct rpcrdma_rep *rep =
-			(struct rpcrdma_rep *)(unsigned long)wc->wr_id;
+	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 */
 	if (wc->status != IB_WC_SUCCESS)
@@ -211,7 +187,8 @@ rpcrdma_recvcq_process_wc(struct ib_wc *wc)
 	ib_dma_sync_single_for_cpu(rep->rr_device,
 				   rdmab_addr(rep->rr_rdmabuf),
 				   rep->rr_len, DMA_FROM_DEVICE);
-	prefetch(rdmab_to_msg(rep->rr_rdmabuf));
+
+	rpcrdma_update_granted_credits(rep);
 
 out_schedule:
 	queue_work(rpcrdma_receive_wq, &rep->rr_work);
@@ -219,57 +196,20 @@ out_schedule:
 
 out_fail:
 	if (wc->status != IB_WC_WR_FLUSH_ERR)
-		pr_err("RPC:       %s: rep %p: %s\n",
-		       __func__, rep, ib_wc_status_msg(wc->status));
+		pr_err("rpcrdma: Recv: %s (%u/0x%x)\n",
+		       ib_wc_status_msg(wc->status),
+		       wc->status, wc->vendor_err);
 	rep->rr_len = RPCRDMA_BAD_LEN;
 	goto out_schedule;
 }
 
-/* The wc array is on stack: automatic memory is always CPU-local.
- *
- * struct ib_wc is 64 bytes, making the poll array potentially
- * large. But this is at the bottom of the call chain. Further
- * substantial work is done in another thread.
- */
-static void
-rpcrdma_recvcq_poll(struct ib_cq *cq)
-{
-	struct ib_wc *pos, wcs[4];
-	int count, rc;
-
-	do {
-		pos = wcs;
-
-		rc = ib_poll_cq(cq, ARRAY_SIZE(wcs), pos);
-		if (rc < 0)
-			break;
-
-		count = rc;
-		while (count-- > 0)
-			rpcrdma_recvcq_process_wc(pos++);
-	} while (rc == ARRAY_SIZE(wcs));
-}
-
-/* Handle provider receive completion upcalls.
- */
-static void
-rpcrdma_recvcq_upcall(struct ib_cq *cq, void *cq_context)
-{
-	do {
-		rpcrdma_recvcq_poll(cq);
-	} while (ib_req_notify_cq(cq, IB_CQ_NEXT_COMP |
-				  IB_CQ_REPORT_MISSED_EVENTS) > 0);
-}
-
 static void
 rpcrdma_flush_cqs(struct rpcrdma_ep *ep)
 {
 	struct ib_wc wc;
 
 	while (ib_poll_cq(ep->rep_attr.recv_cq, 1, &wc) > 0)
-		rpcrdma_recvcq_process_wc(&wc);
-	while (ib_poll_cq(ep->rep_attr.send_cq, 1, &wc) > 0)
-		rpcrdma_sendcq_process_wc(&wc);
+		rpcrdma_receive_wc(NULL, &wc);
 }
 
 static int
@@ -330,6 +270,7 @@ rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event)
 connected:
 		dprintk("RPC:       %s: %sconnected\n",
 					__func__, connstate > 0 ? "" : "dis");
+		atomic_set(&xprt->rx_buf.rb_credits, 1);
 		ep->rep_connected = connstate;
 		rpcrdma_conn_func(ep);
 		wake_up_all(&ep->rep_connect_wait);
@@ -560,9 +501,8 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
 				struct rpcrdma_create_data_internal *cdata)
 {
 	struct ib_cq *sendcq, *recvcq;
-	struct ib_cq_init_attr cq_attr = {};
 	unsigned int max_qp_wr;
-	int rc, err;
+	int rc;
 
 	if (ia->ri_device->attrs.max_sge < RPCRDMA_MAX_IOVS) {
 		dprintk("RPC:       %s: insufficient sge's available\n",
@@ -614,9 +554,9 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
 	init_waitqueue_head(&ep->rep_connect_wait);
 	INIT_DELAYED_WORK(&ep->rep_connect_worker, rpcrdma_connect_worker);
 
-	cq_attr.cqe = ep->rep_attr.cap.max_send_wr + 1;
-	sendcq = ib_create_cq(ia->ri_device, rpcrdma_sendcq_upcall,
-			      rpcrdma_cq_async_error_upcall, NULL, &cq_attr);
+	sendcq = ib_alloc_cq(ia->ri_device, NULL,
+			     ep->rep_attr.cap.max_send_wr + 1,
+			     0, IB_POLL_SOFTIRQ);
 	if (IS_ERR(sendcq)) {
 		rc = PTR_ERR(sendcq);
 		dprintk("RPC:       %s: failed to create send CQ: %i\n",
@@ -624,16 +564,9 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
 		goto out1;
 	}
 
-	rc = ib_req_notify_cq(sendcq, IB_CQ_NEXT_COMP);
-	if (rc) {
-		dprintk("RPC:       %s: ib_req_notify_cq failed: %i\n",
-			__func__, rc);
-		goto out2;
-	}
-
-	cq_attr.cqe = ep->rep_attr.cap.max_recv_wr + 1;
-	recvcq = ib_create_cq(ia->ri_device, rpcrdma_recvcq_upcall,
-			      rpcrdma_cq_async_error_upcall, NULL, &cq_attr);
+	recvcq = ib_alloc_cq(ia->ri_device, NULL,
+			     ep->rep_attr.cap.max_recv_wr + 1,
+			     0, IB_POLL_SOFTIRQ);
 	if (IS_ERR(recvcq)) {
 		rc = PTR_ERR(recvcq);
 		dprintk("RPC:       %s: failed to create recv CQ: %i\n",
@@ -641,14 +574,6 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
 		goto out2;
 	}
 
-	rc = ib_req_notify_cq(recvcq, IB_CQ_NEXT_COMP);
-	if (rc) {
-		dprintk("RPC:       %s: ib_req_notify_cq failed: %i\n",
-			__func__, rc);
-		ib_destroy_cq(recvcq);
-		goto out2;
-	}
-
 	ep->rep_attr.send_cq = sendcq;
 	ep->rep_attr.recv_cq = recvcq;
 
@@ -673,10 +598,7 @@ rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
 	return 0;
 
 out2:
-	err = ib_destroy_cq(sendcq);
-	if (err)
-		dprintk("RPC:       %s: ib_destroy_cq returned %i\n",
-			__func__, err);
+	ib_free_cq(sendcq);
 out1:
 	if (ia->ri_dma_mr)
 		ib_dereg_mr(ia->ri_dma_mr);
@@ -711,15 +633,8 @@ rpcrdma_ep_destroy(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
 		ia->ri_id->qp = NULL;
 	}
 
-	rc = ib_destroy_cq(ep->rep_attr.recv_cq);
-	if (rc)
-		dprintk("RPC:       %s: ib_destroy_cq returned %i\n",
-			__func__, rc);
-
-	rc = ib_destroy_cq(ep->rep_attr.send_cq);
-	if (rc)
-		dprintk("RPC:       %s: ib_destroy_cq returned %i\n",
-			__func__, rc);
+	ib_free_cq(ep->rep_attr.recv_cq);
+	ib_free_cq(ep->rep_attr.send_cq);
 
 	if (ia->ri_dma_mr) {
 		rc = ib_dereg_mr(ia->ri_dma_mr);
@@ -898,6 +813,7 @@ rpcrdma_create_req(struct rpcrdma_xprt *r_xprt)
 	spin_lock(&buffer->rb_reqslock);
 	list_add(&req->rl_all, &buffer->rb_allreqs);
 	spin_unlock(&buffer->rb_reqslock);
+	req->rl_cqe.done = rpcrdma_wc_send;
 	req->rl_buffer = &r_xprt->rx_buf;
 	return req;
 }
@@ -923,6 +839,7 @@ rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt)
 	}
 
 	rep->rr_device = ia->ri_device;
+	rep->rr_cqe.done = rpcrdma_receive_wc;
 	rep->rr_rxprt = r_xprt;
 	INIT_WORK(&rep->rr_work, rpcrdma_receive_worker);
 	return rep;
@@ -943,6 +860,7 @@ rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
 	buf->rb_max_requests = r_xprt->rx_data.max_requests;
 	buf->rb_bc_srv_max_requests = 0;
 	spin_lock_init(&buf->rb_lock);
+	atomic_set(&buf->rb_credits, 1);
 
 	rc = ia->ri_ops->ro_init(r_xprt);
 	if (rc)
@@ -1259,7 +1177,7 @@ rpcrdma_ep_post(struct rpcrdma_ia *ia,
 	}
 
 	send_wr.next = NULL;
-	send_wr.wr_id = RPCRDMA_IGNORE_COMPLETION;
+	send_wr.wr_cqe = &req->rl_cqe;
 	send_wr.sg_list = iov;
 	send_wr.num_sge = req->rl_niovs;
 	send_wr.opcode = IB_WR_SEND;
@@ -1297,7 +1215,7 @@ rpcrdma_ep_post_recv(struct rpcrdma_ia *ia,
 	int rc;
 
 	recv_wr.next = NULL;
-	recv_wr.wr_id = (u64) (unsigned long) rep;
+	recv_wr.wr_cqe = &rep->rr_cqe;
 	recv_wr.sg_list = &rep->rr_rdmabuf->rg_iov;
 	recv_wr.num_sge = 1;
 
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index 38fe11b09875..2ebc743cb96f 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -95,10 +95,6 @@ struct rpcrdma_ep {
 #define INIT_CQCOUNT(ep) atomic_set(&(ep)->rep_cqcount, (ep)->rep_cqinit)
 #define DECR_CQCOUNT(ep) atomic_sub_return(1, &(ep)->rep_cqcount)
 
-/* Force completion handler to ignore the signal
- */
-#define RPCRDMA_IGNORE_COMPLETION	(0ULL)
-
 /* Pre-allocate extra Work Requests for handling backward receives
  * and sends. This is a fixed value because the Work Queues are
  * allocated when the forward channel is set up.
@@ -171,6 +167,7 @@ rdmab_to_msg(struct rpcrdma_regbuf *rb)
 struct rpcrdma_buffer;
 
 struct rpcrdma_rep {
+	struct ib_cqe		rr_cqe;
 	unsigned int		rr_len;
 	struct ib_device	*rr_device;
 	struct rpcrdma_xprt	*rr_rxprt;
@@ -204,11 +201,11 @@ struct rpcrdma_frmr {
 	struct scatterlist		*sg;
 	int				sg_nents;
 	struct ib_mr			*fr_mr;
+	struct ib_cqe			fr_cqe;
 	enum rpcrdma_frmr_state		fr_state;
+	struct completion		fr_linv_done;
 	struct work_struct		fr_work;
 	struct rpcrdma_xprt		*fr_xprt;
-	bool				fr_waiter;
-	struct completion		fr_linv_done;;
 	union {
 		struct ib_reg_wr	fr_regwr;
 		struct ib_send_wr	fr_invwr;
@@ -224,8 +221,7 @@ struct rpcrdma_mw {
 	union {
 		struct rpcrdma_fmr	fmr;
 		struct rpcrdma_frmr	frmr;
-	} r;
-	void			(*mw_sendcompletion)(struct ib_wc *);
+	};
 	struct list_head	mw_list;
 	struct list_head	mw_all;
 };
@@ -281,6 +277,7 @@ struct rpcrdma_req {
 	struct rpcrdma_regbuf	*rl_sendbuf;
 	struct rpcrdma_mr_seg	rl_segments[RPCRDMA_MAX_SEGS];
 
+	struct ib_cqe		rl_cqe;
 	struct list_head	rl_all;
 	bool			rl_backchannel;
 };
@@ -311,6 +308,7 @@ struct rpcrdma_buffer {
 	struct list_head	rb_send_bufs;
 	struct list_head	rb_recv_bufs;
 	u32			rb_max_requests;
+	atomic_t		rb_credits;	/* most recent credit grant */
 
 	u32			rb_bc_srv_max_requests;
 	spinlock_t		rb_reqslock;	/* protect rb_allreqs */
diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index fde2138b81e7..65e759569e48 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1844,9 +1844,7 @@ static int xs_bind(struct sock_xprt *transport, struct socket *sock)
  */
 static void xs_local_rpcbind(struct rpc_task *task)
 {
-	rcu_read_lock();
-	xprt_set_bound(rcu_dereference(task->tk_client->cl_xprt));
-	rcu_read_unlock();
+	xprt_set_bound(task->tk_xprt);
 }
 
 static void xs_local_set_port(struct rpc_xprt *xprt, unsigned short port)