Adding upstream version 4.19.249.upstream/4.19.249

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

1 files changed, 2896 insertions, 0 deletions

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
new file mode 100644
index 000000000..0d7d149b1
--- /dev/null
+++ b/net/sunrpc/clnt.c
@@ -0,0 +1,2896 @@
+/*
+ *  linux/net/sunrpc/clnt.c
+ *
+ *  This file contains the high-level RPC interface.
+ *  It is modeled as a finite state machine to support both synchronous
+ *  and asynchronous requests.
+ *
+ *  -	RPC header generation and argument serialization.
+ *  -	Credential refresh.
+ *  -	TCP connect handling.
+ *  -	Retry of operation when it is suspected the operation failed because
+ *	of uid squashing on the server, or when the credentials were stale
+ *	and need to be refreshed, or when a packet was damaged in transit.
+ *	This may be have to be moved to the VFS layer.
+ *
+ *  Copyright (C) 1992,1993 Rick Sladkey <jrs@world.std.com>
+ *  Copyright (C) 1995,1996 Olaf Kirch <okir@monad.swb.de>
+ */
+
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kallsyms.h>
+#include <linux/mm.h>
+#include <linux/namei.h>
+#include <linux/mount.h>
+#include <linux/slab.h>
+#include <linux/rcupdate.h>
+#include <linux/utsname.h>
+#include <linux/workqueue.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/un.h>
+
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/addr.h>
+#include <linux/sunrpc/rpc_pipe_fs.h>
+#include <linux/sunrpc/metrics.h>
+#include <linux/sunrpc/bc_xprt.h>
+#include <trace/events/sunrpc.h>
+
+#include "sunrpc.h"
+#include "netns.h"
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+# define RPCDBG_FACILITY	RPCDBG_CALL
+#endif
+
+#define dprint_status(t)					\
+	dprintk("RPC: %5u %s (status %d)\n", t->tk_pid,		\
+			__func__, t->tk_status)
+
+/*
+ * All RPC clients are linked into this list
+ */
+
+static DECLARE_WAIT_QUEUE_HEAD(destroy_wait);
+
+
+static void	call_start(struct rpc_task *task);
+static void	call_reserve(struct rpc_task *task);
+static void	call_reserveresult(struct rpc_task *task);
+static void	call_allocate(struct rpc_task *task);
+static void	call_decode(struct rpc_task *task);
+static void	call_bind(struct rpc_task *task);
+static void	call_bind_status(struct rpc_task *task);
+static void	call_transmit(struct rpc_task *task);
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+static void	call_bc_transmit(struct rpc_task *task);
+#endif /* CONFIG_SUNRPC_BACKCHANNEL */
+static void	call_status(struct rpc_task *task);
+static void	call_transmit_status(struct rpc_task *task);
+static void	call_refresh(struct rpc_task *task);
+static void	call_refreshresult(struct rpc_task *task);
+static void	call_timeout(struct rpc_task *task);
+static void	call_connect(struct rpc_task *task);
+static void	call_connect_status(struct rpc_task *task);
+
+static __be32	*rpc_encode_header(struct rpc_task *task);
+static __be32	*rpc_verify_header(struct rpc_task *task);
+static int	rpc_ping(struct rpc_clnt *clnt);
+
+static void rpc_register_client(struct rpc_clnt *clnt)
+{
+	struct net *net = rpc_net_ns(clnt);
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+	spin_lock(&sn->rpc_client_lock);
+	list_add(&clnt->cl_clients, &sn->all_clients);
+	spin_unlock(&sn->rpc_client_lock);
+}
+
+static void rpc_unregister_client(struct rpc_clnt *clnt)
+{
+	struct net *net = rpc_net_ns(clnt);
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+	spin_lock(&sn->rpc_client_lock);
+	list_del(&clnt->cl_clients);
+	spin_unlock(&sn->rpc_client_lock);
+}
+
+static void __rpc_clnt_remove_pipedir(struct rpc_clnt *clnt)
+{
+	rpc_remove_client_dir(clnt);
+}
+
+static void rpc_clnt_remove_pipedir(struct rpc_clnt *clnt)
+{
+	struct net *net = rpc_net_ns(clnt);
+	struct super_block *pipefs_sb;
+
+	pipefs_sb = rpc_get_sb_net(net);
+	if (pipefs_sb) {
+		__rpc_clnt_remove_pipedir(clnt);
+		rpc_put_sb_net(net);
+	}
+}
+
+static struct dentry *rpc_setup_pipedir_sb(struct super_block *sb,
+				    struct rpc_clnt *clnt)
+{
+	static uint32_t clntid;
+	const char *dir_name = clnt->cl_program->pipe_dir_name;
+	char name[15];
+	struct dentry *dir, *dentry;
+
+	dir = rpc_d_lookup_sb(sb, dir_name);
+	if (dir == NULL) {
+		pr_info("RPC: pipefs directory doesn't exist: %s\n", dir_name);
+		return dir;
+	}
+	for (;;) {
+		snprintf(name, sizeof(name), "clnt%x", (unsigned int)clntid++);
+		name[sizeof(name) - 1] = '\0';
+		dentry = rpc_create_client_dir(dir, name, clnt);
+		if (!IS_ERR(dentry))
+			break;
+		if (dentry == ERR_PTR(-EEXIST))
+			continue;
+		printk(KERN_INFO "RPC: Couldn't create pipefs entry"
+				" %s/%s, error %ld\n",
+				dir_name, name, PTR_ERR(dentry));
+		break;
+	}
+	dput(dir);
+	return dentry;
+}
+
+static int
+rpc_setup_pipedir(struct super_block *pipefs_sb, struct rpc_clnt *clnt)
+{
+	struct dentry *dentry;
+
+	if (clnt->cl_program->pipe_dir_name != NULL) {
+		dentry = rpc_setup_pipedir_sb(pipefs_sb, clnt);
+		if (IS_ERR(dentry))
+			return PTR_ERR(dentry);
+	}
+	return 0;
+}
+
+static int rpc_clnt_skip_event(struct rpc_clnt *clnt, unsigned long event)
+{
+	if (clnt->cl_program->pipe_dir_name == NULL)
+		return 1;
+
+	switch (event) {
+	case RPC_PIPEFS_MOUNT:
+		if (clnt->cl_pipedir_objects.pdh_dentry != NULL)
+			return 1;
+		if (atomic_read(&clnt->cl_count) == 0)
+			return 1;
+		break;
+	case RPC_PIPEFS_UMOUNT:
+		if (clnt->cl_pipedir_objects.pdh_dentry == NULL)
+			return 1;
+		break;
+	}
+	return 0;
+}
+
+static int __rpc_clnt_handle_event(struct rpc_clnt *clnt, unsigned long event,
+				   struct super_block *sb)
+{
+	struct dentry *dentry;
+
+	switch (event) {
+	case RPC_PIPEFS_MOUNT:
+		dentry = rpc_setup_pipedir_sb(sb, clnt);
+		if (!dentry)
+			return -ENOENT;
+		if (IS_ERR(dentry))
+			return PTR_ERR(dentry);
+		break;
+	case RPC_PIPEFS_UMOUNT:
+		__rpc_clnt_remove_pipedir(clnt);
+		break;
+	default:
+		printk(KERN_ERR "%s: unknown event: %ld\n", __func__, event);
+		return -ENOTSUPP;
+	}
+	return 0;
+}
+
+static int __rpc_pipefs_event(struct rpc_clnt *clnt, unsigned long event,
+				struct super_block *sb)
+{
+	int error = 0;
+
+	for (;; clnt = clnt->cl_parent) {
+		if (!rpc_clnt_skip_event(clnt, event))
+			error = __rpc_clnt_handle_event(clnt, event, sb);
+		if (error || clnt == clnt->cl_parent)
+			break;
+	}
+	return error;
+}
+
+static struct rpc_clnt *rpc_get_client_for_event(struct net *net, int event)
+{
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+	struct rpc_clnt *clnt;
+
+	spin_lock(&sn->rpc_client_lock);
+	list_for_each_entry(clnt, &sn->all_clients, cl_clients) {
+		if (rpc_clnt_skip_event(clnt, event))
+			continue;
+		spin_unlock(&sn->rpc_client_lock);
+		return clnt;
+	}
+	spin_unlock(&sn->rpc_client_lock);
+	return NULL;
+}
+
+static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event,
+			    void *ptr)
+{
+	struct super_block *sb = ptr;
+	struct rpc_clnt *clnt;
+	int error = 0;
+
+	while ((clnt = rpc_get_client_for_event(sb->s_fs_info, event))) {
+		error = __rpc_pipefs_event(clnt, event, sb);
+		if (error)
+			break;
+	}
+	return error;
+}
+
+static struct notifier_block rpc_clients_block = {
+	.notifier_call	= rpc_pipefs_event,
+	.priority	= SUNRPC_PIPEFS_RPC_PRIO,
+};
+
+int rpc_clients_notifier_register(void)
+{
+	return rpc_pipefs_notifier_register(&rpc_clients_block);
+}
+
+void rpc_clients_notifier_unregister(void)
+{
+	return rpc_pipefs_notifier_unregister(&rpc_clients_block);
+}
+
+static struct rpc_xprt *rpc_clnt_set_transport(struct rpc_clnt *clnt,
+		struct rpc_xprt *xprt,
+		const struct rpc_timeout *timeout)
+{
+	struct rpc_xprt *old;
+
+	spin_lock(&clnt->cl_lock);
+	old = rcu_dereference_protected(clnt->cl_xprt,
+			lockdep_is_held(&clnt->cl_lock));
+
+	if (!xprt_bound(xprt))
+		clnt->cl_autobind = 1;
+
+	clnt->cl_timeout = timeout;
+	rcu_assign_pointer(clnt->cl_xprt, xprt);
+	spin_unlock(&clnt->cl_lock);
+
+	return old;
+}
+
+static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename)
+{
+	clnt->cl_nodelen = strlcpy(clnt->cl_nodename,
+			nodename, sizeof(clnt->cl_nodename));
+}
+
+static int rpc_client_register(struct rpc_clnt *clnt,
+			       rpc_authflavor_t pseudoflavor,
+			       const char *client_name)
+{
+	struct rpc_auth_create_args auth_args = {
+		.pseudoflavor = pseudoflavor,
+		.target_name = client_name,
+	};
+	struct rpc_auth *auth;
+	struct net *net = rpc_net_ns(clnt);
+	struct super_block *pipefs_sb;
+	int err;
+
+	rpc_clnt_debugfs_register(clnt);
+
+	pipefs_sb = rpc_get_sb_net(net);
+	if (pipefs_sb) {
+		err = rpc_setup_pipedir(pipefs_sb, clnt);
+		if (err)
+			goto out;
+	}
+
+	rpc_register_client(clnt);
+	if (pipefs_sb)
+		rpc_put_sb_net(net);
+
+	auth = rpcauth_create(&auth_args, clnt);
+	if (IS_ERR(auth)) {
+		dprintk("RPC:       Couldn't create auth handle (flavor %u)\n",
+				pseudoflavor);
+		err = PTR_ERR(auth);
+		goto err_auth;
+	}
+	return 0;
+err_auth:
+	pipefs_sb = rpc_get_sb_net(net);
+	rpc_unregister_client(clnt);
+	__rpc_clnt_remove_pipedir(clnt);
+out:
+	if (pipefs_sb)
+		rpc_put_sb_net(net);
+	rpc_clnt_debugfs_unregister(clnt);
+	return err;
+}
+
+static DEFINE_IDA(rpc_clids);
+
+void rpc_cleanup_clids(void)
+{
+	ida_destroy(&rpc_clids);
+}
+
+static int rpc_alloc_clid(struct rpc_clnt *clnt)
+{
+	int clid;
+
+	clid = ida_simple_get(&rpc_clids, 0, 0, GFP_KERNEL);
+	if (clid < 0)
+		return clid;
+	clnt->cl_clid = clid;
+	return 0;
+}
+
+static void rpc_free_clid(struct rpc_clnt *clnt)
+{
+	ida_simple_remove(&rpc_clids, clnt->cl_clid);
+}
+
+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)
+{
+	const struct rpc_program *program = args->program;
+	const struct rpc_version *version;
+	struct rpc_clnt *clnt = NULL;
+	const struct rpc_timeout *timeout;
+	const char *nodename = args->nodename;
+	int err;
+
+	/* sanity check the name before trying to print it */
+	dprintk("RPC:       creating %s client for %s (xprt %p)\n",
+			program->name, args->servername, xprt);
+
+	err = rpciod_up();
+	if (err)
+		goto out_no_rpciod;
+
+	err = -EINVAL;
+	if (args->version >= program->nrvers)
+		goto out_err;
+	version = program->version[args->version];
+	if (version == NULL)
+		goto out_err;
+
+	err = -ENOMEM;
+	clnt = kzalloc(sizeof(*clnt), GFP_KERNEL);
+	if (!clnt)
+		goto out_err;
+	clnt->cl_parent = parent ? : clnt;
+
+	err = rpc_alloc_clid(clnt);
+	if (err)
+		goto out_no_clid;
+
+	clnt->cl_procinfo = version->procs;
+	clnt->cl_maxproc  = version->nrprocs;
+	clnt->cl_prog     = args->prognumber ? : program->number;
+	clnt->cl_vers     = version->number;
+	clnt->cl_stats    = program->stats;
+	clnt->cl_metrics  = rpc_alloc_iostats(clnt);
+	rpc_init_pipe_dir_head(&clnt->cl_pipedir_objects);
+	err = -ENOMEM;
+	if (clnt->cl_metrics == NULL)
+		goto out_no_stats;
+	clnt->cl_program  = program;
+	INIT_LIST_HEAD(&clnt->cl_tasks);
+	spin_lock_init(&clnt->cl_lock);
+
+	timeout = xprt->timeout;
+	if (args->timeout != NULL) {
+		memcpy(&clnt->cl_timeout_default, args->timeout,
+				sizeof(clnt->cl_timeout_default));
+		timeout = &clnt->cl_timeout_default;
+	}
+
+	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);
+
+	atomic_set(&clnt->cl_count, 1);
+
+	if (nodename == NULL)
+		nodename = utsname()->nodename;
+	/* save the nodename */
+	rpc_clnt_set_nodename(clnt, nodename);
+
+	err = rpc_client_register(clnt, args->authflavor, args->client_name);
+	if (err)
+		goto out_no_path;
+	if (parent)
+		atomic_inc(&parent->cl_count);
+	return clnt;
+
+out_no_path:
+	rpc_free_iostats(clnt->cl_metrics);
+out_no_stats:
+	rpc_free_clid(clnt);
+out_no_clid:
+	kfree(clnt);
+out_err:
+	rpciod_down();
+out_no_rpciod:
+	xprt_switch_put(xps);
+	xprt_put(xprt);
+	return ERR_PTR(err);
+}
+
+static 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;
+
+	if (args->bc_xprt && args->bc_xprt->xpt_bc_xps) {
+		WARN_ON_ONCE(!(args->protocol & XPRT_TRANSPORT_BC));
+		xps = args->bc_xprt->xpt_bc_xps;
+		xprt_switch_get(xps);
+	} else {
+		xps = xprt_switch_alloc(xprt, GFP_KERNEL);
+		if (xps == NULL) {
+			xprt_put(xprt);
+			return ERR_PTR(-ENOMEM);
+		}
+		if (xprt->bc_xprt) {
+			xprt_switch_get(xps);
+			xprt->bc_xprt->xpt_bc_xps = xps;
+		}
+	}
+	clnt = rpc_new_client(args, xps, xprt, NULL);
+	if (IS_ERR(clnt))
+		return clnt;
+
+	if (!(args->flags & RPC_CLNT_CREATE_NOPING)) {
+		int err = rpc_ping(clnt);
+		if (err != 0) {
+			rpc_shutdown_client(clnt);
+			return ERR_PTR(err);
+		}
+	}
+
+	clnt->cl_softrtry = 1;
+	if (args->flags & RPC_CLNT_CREATE_HARDRTRY)
+		clnt->cl_softrtry = 0;
+
+	if (args->flags & RPC_CLNT_CREATE_AUTOBIND)
+		clnt->cl_autobind = 1;
+	if (args->flags & RPC_CLNT_CREATE_NO_RETRANS_TIMEOUT)
+		clnt->cl_noretranstimeo = 1;
+	if (args->flags & RPC_CLNT_CREATE_DISCRTRY)
+		clnt->cl_discrtry = 1;
+	if (!(args->flags & RPC_CLNT_CREATE_QUIET))
+		clnt->cl_chatty = 1;
+
+	return clnt;
+}
+
+/**
+ * rpc_create - create an RPC client and transport with one call
+ * @args: rpc_clnt create argument structure
+ *
+ * Creates and initializes an RPC transport and an RPC client.
+ *
+ * It can ping the server in order to determine if it is up, and to see if
+ * it supports this program and version.  RPC_CLNT_CREATE_NOPING disables
+ * this behavior so asynchronous tasks can also use rpc_create.
+ */
+struct rpc_clnt *rpc_create(struct rpc_create_args *args)
+{
+	struct rpc_xprt *xprt;
+	struct xprt_create xprtargs = {
+		.net = args->net,
+		.ident = args->protocol,
+		.srcaddr = args->saddress,
+		.dstaddr = args->address,
+		.addrlen = args->addrsize,
+		.servername = args->servername,
+		.bc_xprt = args->bc_xprt,
+	};
+	char servername[48];
+
+	if (args->bc_xprt) {
+		WARN_ON_ONCE(!(args->protocol & XPRT_TRANSPORT_BC));
+		xprt = args->bc_xprt->xpt_bc_xprt;
+		if (xprt) {
+			xprt_get(xprt);
+			return rpc_create_xprt(args, xprt);
+		}
+	}
+
+	if (args->flags & RPC_CLNT_CREATE_INFINITE_SLOTS)
+		xprtargs.flags |= XPRT_CREATE_INFINITE_SLOTS;
+	if (args->flags & RPC_CLNT_CREATE_NO_IDLE_TIMEOUT)
+		xprtargs.flags |= XPRT_CREATE_NO_IDLE_TIMEOUT;
+	/*
+	 * If the caller chooses not to specify a hostname, whip
+	 * up a string representation of the passed-in address.
+	 */
+	if (xprtargs.servername == NULL) {
+		struct sockaddr_un *sun =
+				(struct sockaddr_un *)args->address;
+		struct sockaddr_in *sin =
+				(struct sockaddr_in *)args->address;
+		struct sockaddr_in6 *sin6 =
+				(struct sockaddr_in6 *)args->address;
+
+		servername[0] = '\0';
+		switch (args->address->sa_family) {
+		case AF_LOCAL:
+			snprintf(servername, sizeof(servername), "%s",
+				 sun->sun_path);
+			break;
+		case AF_INET:
+			snprintf(servername, sizeof(servername), "%pI4",
+				 &sin->sin_addr.s_addr);
+			break;
+		case AF_INET6:
+			snprintf(servername, sizeof(servername), "%pI6",
+				 &sin6->sin6_addr);
+			break;
+		default:
+			/* caller wants default server name, but
+			 * address family isn't recognized. */
+			return ERR_PTR(-EINVAL);
+		}
+		xprtargs.servername = servername;
+	}
+
+	xprt = xprt_create_transport(&xprtargs);
+	if (IS_ERR(xprt))
+		return (struct rpc_clnt *)xprt;
+
+	/*
+	 * By default, kernel RPC client connects from a reserved port.
+	 * CAP_NET_BIND_SERVICE will not be set for unprivileged requesters,
+	 * but it is always enabled for rpciod, which handles the connect
+	 * operation.
+	 */
+	xprt->resvport = 1;
+	if (args->flags & RPC_CLNT_CREATE_NONPRIVPORT)
+		xprt->resvport = 0;
+
+	return rpc_create_xprt(args, xprt);
+}
+EXPORT_SYMBOL_GPL(rpc_create);
+
+/*
+ * This function clones the RPC client structure. It allows us to share the
+ * same transport while varying parameters such as the authentication
+ * flavour.
+ */
+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;
+
+	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 || 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, xps, xprt, clnt);
+	if (IS_ERR(new)) {
+		err = PTR_ERR(new);
+		goto out_err;
+	}
+
+	/* Turn off autobind on clones */
+	new->cl_autobind = 0;
+	new->cl_softrtry = clnt->cl_softrtry;
+	new->cl_noretranstimeo = clnt->cl_noretranstimeo;
+	new->cl_discrtry = clnt->cl_discrtry;
+	new->cl_chatty = clnt->cl_chatty;
+	return new;
+
+out_err:
+	dprintk("RPC:       %s: returned error %d\n", __func__, err);
+	return ERR_PTR(err);
+}
+
+/**
+ * rpc_clone_client - Clone an RPC client structure
+ *
+ * @clnt: RPC client whose parameters are copied
+ *
+ * Returns a fresh RPC client or an ERR_PTR.
+ */
+struct rpc_clnt *rpc_clone_client(struct rpc_clnt *clnt)
+{
+	struct rpc_create_args args = {
+		.program	= clnt->cl_program,
+		.prognumber	= clnt->cl_prog,
+		.version	= clnt->cl_vers,
+		.authflavor	= clnt->cl_auth->au_flavor,
+	};
+	return __rpc_clone_client(&args, clnt);
+}
+EXPORT_SYMBOL_GPL(rpc_clone_client);
+
+/**
+ * rpc_clone_client_set_auth - Clone an RPC client structure and set its auth
+ *
+ * @clnt: RPC client whose parameters are copied
+ * @flavor: security flavor for new client
+ *
+ * Returns a fresh RPC client or an ERR_PTR.
+ */
+struct rpc_clnt *
+rpc_clone_client_set_auth(struct rpc_clnt *clnt, rpc_authflavor_t flavor)
+{
+	struct rpc_create_args args = {
+		.program	= clnt->cl_program,
+		.prognumber	= clnt->cl_prog,
+		.version	= clnt->cl_vers,
+		.authflavor	= flavor,
+	};
+	return __rpc_clone_client(&args, clnt);
+}
+EXPORT_SYMBOL_GPL(rpc_clone_client_set_auth);
+
+/**
+ * rpc_switch_client_transport: switch the RPC transport on the fly
+ * @clnt: pointer to a struct rpc_clnt
+ * @args: pointer to the new transport arguments
+ * @timeout: pointer to the new timeout parameters
+ *
+ * This function allows the caller to switch the RPC transport for the
+ * rpc_clnt structure 'clnt' to allow it to connect to a mirrored NFS
+ * server, for instance.  It assumes that the caller has ensured that
+ * there are no active RPC tasks by using some form of locking.
+ *
+ * Returns zero if "clnt" is now using the new xprt.  Otherwise a
+ * negative errno is returned, and "clnt" continues to use the old
+ * xprt.
+ */
+int rpc_switch_client_transport(struct rpc_clnt *clnt,
+		struct xprt_create *args,
+		const struct rpc_timeout *timeout)
+{
+	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;
+
+	xprt = xprt_create_transport(args);
+	if (IS_ERR(xprt)) {
+		dprintk("RPC:       failed to create new xprt for clnt %p\n",
+			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);
+	rpc_clnt_debugfs_unregister(clnt);
+
+	/*
+	 * A new transport was created.  "clnt" therefore
+	 * becomes the root of a new cl_parent tree.  clnt's
+	 * children, if it has any, still point to the old xprt.
+	 */
+	parent = clnt->cl_parent;
+	clnt->cl_parent = clnt;
+
+	/*
+	 * The old rpc_auth cache cannot be re-used.  GSS
+	 * contexts in particular are between a single
+	 * client and server.
+	 */
+	err = rpc_client_register(clnt, pseudoflavor, NULL);
+	if (err)
+		goto out_revert;
+
+	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?
+ */
+void rpc_killall_tasks(struct rpc_clnt *clnt)
+{
+	struct rpc_task	*rovr;
+
+
+	if (list_empty(&clnt->cl_tasks))
+		return;
+	dprintk("RPC:       killing all tasks for client %p\n", clnt);
+	/*
+	 * Spin lock all_tasks to prevent changes...
+	 */
+	spin_lock(&clnt->cl_lock);
+	list_for_each_entry(rovr, &clnt->cl_tasks, tk_task) {
+		if (!RPC_IS_ACTIVATED(rovr))
+			continue;
+		if (!(rovr->tk_flags & RPC_TASK_KILLED)) {
+			rovr->tk_flags |= RPC_TASK_KILLED;
+			rpc_exit(rovr, -EIO);
+			if (RPC_IS_QUEUED(rovr))
+				rpc_wake_up_queued_task(rovr->tk_waitqueue,
+							rovr);
+		}
+	}
+	spin_unlock(&clnt->cl_lock);
+}
+EXPORT_SYMBOL_GPL(rpc_killall_tasks);
+
+/*
+ * Properly shut down an RPC client, terminating all outstanding
+ * requests.
+ */
+void rpc_shutdown_client(struct rpc_clnt *clnt)
+{
+	might_sleep();
+
+	dprintk_rcu("RPC:       shutting down %s client for %s\n",
+			clnt->cl_program->name,
+			rcu_dereference(clnt->cl_xprt)->servername);
+
+	while (!list_empty(&clnt->cl_tasks)) {
+		rpc_killall_tasks(clnt);
+		wait_event_timeout(destroy_wait,
+			list_empty(&clnt->cl_tasks), 1*HZ);
+	}
+
+	rpc_release_client(clnt);
+}
+EXPORT_SYMBOL_GPL(rpc_shutdown_client);
+
+/*
+ * Free an RPC client
+ */
+static struct rpc_clnt *
+rpc_free_client(struct rpc_clnt *clnt)
+{
+	struct rpc_clnt *parent = NULL;
+
+	dprintk_rcu("RPC:       destroying %s client for %s\n",
+			clnt->cl_program->name,
+			rcu_dereference(clnt->cl_xprt)->servername);
+	if (clnt->cl_parent != clnt)
+		parent = clnt->cl_parent;
+	rpc_clnt_debugfs_unregister(clnt);
+	rpc_clnt_remove_pipedir(clnt);
+	rpc_unregister_client(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);
+	return parent;
+}
+
+/*
+ * Free an RPC client
+ */
+static struct rpc_clnt *
+rpc_free_auth(struct rpc_clnt *clnt)
+{
+	if (clnt->cl_auth == NULL)
+		return rpc_free_client(clnt);
+
+	/*
+	 * Note: RPCSEC_GSS may need to send NULL RPC calls in order to
+	 *       release remaining GSS contexts. This mechanism ensures
+	 *       that it can do so safely.
+	 */
+	atomic_inc(&clnt->cl_count);
+	rpcauth_release(clnt->cl_auth);
+	clnt->cl_auth = NULL;
+	if (atomic_dec_and_test(&clnt->cl_count))
+		return rpc_free_client(clnt);
+	return NULL;
+}
+
+/*
+ * Release reference to the RPC client
+ */
+void
+rpc_release_client(struct rpc_clnt *clnt)
+{
+	dprintk("RPC:       rpc_release_client(%p)\n", clnt);
+
+	do {
+		if (list_empty(&clnt->cl_tasks))
+			wake_up(&destroy_wait);
+		if (!atomic_dec_and_test(&clnt->cl_count))
+			break;
+		clnt = rpc_free_auth(clnt);
+	} while (clnt != NULL);
+}
+EXPORT_SYMBOL_GPL(rpc_release_client);
+
+/**
+ * rpc_bind_new_program - bind a new RPC program to an existing client
+ * @old: old rpc_client
+ * @program: rpc program to set
+ * @vers: rpc program version
+ *
+ * Clones the rpc client and sets up a new RPC program. This is mainly
+ * of use for enabling different RPC programs to share the same transport.
+ * The Sun NFSv2/v3 ACL protocol can do this.
+ */
+struct rpc_clnt *rpc_bind_new_program(struct rpc_clnt *old,
+				      const struct rpc_program *program,
+				      u32 vers)
+{
+	struct rpc_create_args args = {
+		.program	= program,
+		.prognumber	= program->number,
+		.version	= vers,
+		.authflavor	= old->cl_auth->au_flavor,
+	};
+	struct rpc_clnt *clnt;
+	int err;
+
+	clnt = __rpc_clone_client(&args, old);
+	if (IS_ERR(clnt))
+		goto out;
+	err = rpc_ping(clnt);
+	if (err != 0) {
+		rpc_shutdown_client(clnt);
+		clnt = ERR_PTR(err);
+	}
+out:
+	return clnt;
+}
+EXPORT_SYMBOL_GPL(rpc_bind_new_program);
+
+void rpc_task_release_transport(struct rpc_task *task)
+{
+	struct rpc_xprt *xprt = task->tk_xprt;
+
+	if (xprt) {
+		task->tk_xprt = NULL;
+		xprt_put(xprt);
+	}
+}
+EXPORT_SYMBOL_GPL(rpc_task_release_transport);
+
+void rpc_task_release_client(struct rpc_task *task)
+{
+	struct rpc_clnt *clnt = task->tk_client;
+
+	if (clnt != NULL) {
+		/* Remove from client task list */
+		spin_lock(&clnt->cl_lock);
+		list_del(&task->tk_task);
+		spin_unlock(&clnt->cl_lock);
+		task->tk_client = NULL;
+
+		rpc_release_client(clnt);
+	}
+	rpc_task_release_transport(task);
+}
+
+static
+void rpc_task_set_transport(struct rpc_task *task, struct rpc_clnt *clnt)
+{
+	if (!task->tk_xprt)
+		task->tk_xprt = xprt_iter_get_next(&clnt->cl_xpi);
+}
+
+static
+void rpc_task_set_client(struct rpc_task *task, struct rpc_clnt *clnt)
+{
+
+	if (clnt != NULL) {
+		rpc_task_set_transport(task, clnt);
+		task->tk_client = clnt;
+		atomic_inc(&clnt->cl_count);
+		if (clnt->cl_softrtry)
+			task->tk_flags |= RPC_TASK_SOFT;
+		if (clnt->cl_noretranstimeo)
+			task->tk_flags |= RPC_TASK_NO_RETRANS_TIMEOUT;
+		if (atomic_read(&clnt->cl_swapper))
+			task->tk_flags |= RPC_TASK_SWAPPER;
+		/* Add to the client's list of all tasks */
+		spin_lock(&clnt->cl_lock);
+		list_add_tail(&task->tk_task, &clnt->cl_tasks);
+		spin_unlock(&clnt->cl_lock);
+	}
+}
+
+static void
+rpc_task_set_rpc_message(struct rpc_task *task, const struct rpc_message *msg)
+{
+	if (msg != NULL) {
+		task->tk_msg.rpc_proc = msg->rpc_proc;
+		task->tk_msg.rpc_argp = msg->rpc_argp;
+		task->tk_msg.rpc_resp = msg->rpc_resp;
+		if (msg->rpc_cred != NULL)
+			task->tk_msg.rpc_cred = get_rpccred(msg->rpc_cred);
+	}
+}
+
+/*
+ * Default callback for async RPC calls
+ */
+static void
+rpc_default_callback(struct rpc_task *task, void *data)
+{
+}
+
+static const struct rpc_call_ops rpc_default_ops = {
+	.rpc_call_done = rpc_default_callback,
+};
+
+/**
+ * rpc_run_task - Allocate a new RPC task, then run rpc_execute against it
+ * @task_setup_data: pointer to task initialisation data
+ */
+struct rpc_task *rpc_run_task(const struct rpc_task_setup *task_setup_data)
+{
+	struct rpc_task *task;
+
+	task = rpc_new_task(task_setup_data);
+
+	rpc_task_set_client(task, task_setup_data->rpc_client);
+	rpc_task_set_rpc_message(task, task_setup_data->rpc_message);
+
+	if (task->tk_action == NULL)
+		rpc_call_start(task);
+
+	atomic_inc(&task->tk_count);
+	rpc_execute(task);
+	return task;
+}
+EXPORT_SYMBOL_GPL(rpc_run_task);
+
+/**
+ * rpc_call_sync - Perform a synchronous RPC call
+ * @clnt: pointer to RPC client
+ * @msg: RPC call parameters
+ * @flags: RPC call flags
+ */
+int rpc_call_sync(struct rpc_clnt *clnt, const struct rpc_message *msg, int flags)
+{
+	struct rpc_task	*task;
+	struct rpc_task_setup task_setup_data = {
+		.rpc_client = clnt,
+		.rpc_message = msg,
+		.callback_ops = &rpc_default_ops,
+		.flags = flags,
+	};
+	int status;
+
+	WARN_ON_ONCE(flags & RPC_TASK_ASYNC);
+	if (flags & RPC_TASK_ASYNC) {
+		rpc_release_calldata(task_setup_data.callback_ops,
+			task_setup_data.callback_data);
+		return -EINVAL;
+	}
+
+	task = rpc_run_task(&task_setup_data);
+	if (IS_ERR(task))
+		return PTR_ERR(task);
+	status = task->tk_status;
+	rpc_put_task(task);
+	return status;
+}
+EXPORT_SYMBOL_GPL(rpc_call_sync);
+
+/**
+ * rpc_call_async - Perform an asynchronous RPC call
+ * @clnt: pointer to RPC client
+ * @msg: RPC call parameters
+ * @flags: RPC call flags
+ * @tk_ops: RPC call ops
+ * @data: user call data
+ */
+int
+rpc_call_async(struct rpc_clnt *clnt, const struct rpc_message *msg, int flags,
+	       const struct rpc_call_ops *tk_ops, void *data)
+{
+	struct rpc_task	*task;
+	struct rpc_task_setup task_setup_data = {
+		.rpc_client = clnt,
+		.rpc_message = msg,
+		.callback_ops = tk_ops,
+		.callback_data = data,
+		.flags = flags|RPC_TASK_ASYNC,
+	};
+
+	task = rpc_run_task(&task_setup_data);
+	if (IS_ERR(task))
+		return PTR_ERR(task);
+	rpc_put_task(task);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(rpc_call_async);
+
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+/**
+ * rpc_run_bc_task - Allocate a new RPC task for backchannel use, then run
+ * rpc_execute against it
+ * @req: RPC request
+ */
+struct rpc_task *rpc_run_bc_task(struct rpc_rqst *req)
+{
+	struct rpc_task *task;
+	struct xdr_buf *xbufp = &req->rq_snd_buf;
+	struct rpc_task_setup task_setup_data = {
+		.callback_ops = &rpc_default_ops,
+		.flags = RPC_TASK_SOFTCONN,
+	};
+
+	dprintk("RPC: rpc_run_bc_task req= %p\n", req);
+	/*
+	 * Create an rpc_task to send the data
+	 */
+	task = rpc_new_task(&task_setup_data);
+	task->tk_rqstp = req;
+
+	/*
+	 * Set up the xdr_buf length.
+	 * This also indicates that the buffer is XDR encoded already.
+	 */
+	xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
+			xbufp->tail[0].iov_len;
+
+	task->tk_action = call_bc_transmit;
+	atomic_inc(&task->tk_count);
+	WARN_ON_ONCE(atomic_read(&task->tk_count) != 2);
+	rpc_execute(task);
+
+	dprintk("RPC: rpc_run_bc_task: task= %p\n", task);
+	return task;
+}
+#endif /* CONFIG_SUNRPC_BACKCHANNEL */
+
+void
+rpc_call_start(struct rpc_task *task)
+{
+	task->tk_action = call_start;
+}
+EXPORT_SYMBOL_GPL(rpc_call_start);
+
+/**
+ * rpc_peeraddr - extract remote peer address from clnt's xprt
+ * @clnt: RPC client structure
+ * @buf: target buffer
+ * @bufsize: length of target buffer
+ *
+ * Returns the number of bytes that are actually in the stored address.
+ */
+size_t rpc_peeraddr(struct rpc_clnt *clnt, struct sockaddr *buf, size_t bufsize)
+{
+	size_t bytes;
+	struct rpc_xprt *xprt;
+
+	rcu_read_lock();
+	xprt = rcu_dereference(clnt->cl_xprt);
+
+	bytes = xprt->addrlen;
+	if (bytes > bufsize)
+		bytes = bufsize;
+	memcpy(buf, &xprt->addr, bytes);
+	rcu_read_unlock();
+
+	return bytes;
+}
+EXPORT_SYMBOL_GPL(rpc_peeraddr);
+
+/**
+ * rpc_peeraddr2str - return remote peer address in printable format
+ * @clnt: RPC client structure
+ * @format: address format
+ *
+ * NB: the lifetime of the memory referenced by the returned pointer is
+ * the same as the rpc_xprt itself.  As long as the caller uses this
+ * pointer, it must hold the RCU read lock.
+ */
+const char *rpc_peeraddr2str(struct rpc_clnt *clnt,
+			     enum rpc_display_format_t format)
+{
+	struct rpc_xprt *xprt;
+
+	xprt = rcu_dereference(clnt->cl_xprt);
+
+	if (xprt->address_strings[format] != NULL)
+		return xprt->address_strings[format];
+	else
+		return "unprintable";
+}
+EXPORT_SYMBOL_GPL(rpc_peeraddr2str);
+
+static const struct sockaddr_in rpc_inaddr_loopback = {
+	.sin_family		= AF_INET,
+	.sin_addr.s_addr	= htonl(INADDR_ANY),
+};
+
+static const struct sockaddr_in6 rpc_in6addr_loopback = {
+	.sin6_family		= AF_INET6,
+	.sin6_addr		= IN6ADDR_ANY_INIT,
+};
+
+/*
+ * Try a getsockname() on a connected datagram socket.  Using a
+ * connected datagram socket prevents leaving a socket in TIME_WAIT.
+ * This conserves the ephemeral port number space.
+ *
+ * Returns zero and fills in "buf" if successful; otherwise, a
+ * negative errno is returned.
+ */
+static int rpc_sockname(struct net *net, struct sockaddr *sap, size_t salen,
+			struct sockaddr *buf)
+{
+	struct socket *sock;
+	int err;
+
+	err = __sock_create(net, sap->sa_family,
+				SOCK_DGRAM, IPPROTO_UDP, &sock, 1);
+	if (err < 0) {
+		dprintk("RPC:       can't create UDP socket (%d)\n", err);
+		goto out;
+	}
+
+	switch (sap->sa_family) {
+	case AF_INET:
+		err = kernel_bind(sock,
+				(struct sockaddr *)&rpc_inaddr_loopback,
+				sizeof(rpc_inaddr_loopback));
+		break;
+	case AF_INET6:
+		err = kernel_bind(sock,
+				(struct sockaddr *)&rpc_in6addr_loopback,
+				sizeof(rpc_in6addr_loopback));
+		break;
+	default:
+		err = -EAFNOSUPPORT;
+		goto out;
+	}
+	if (err < 0) {
+		dprintk("RPC:       can't bind UDP socket (%d)\n", err);
+		goto out_release;
+	}
+
+	err = kernel_connect(sock, sap, salen, 0);
+	if (err < 0) {
+		dprintk("RPC:       can't connect UDP socket (%d)\n", err);
+		goto out_release;
+	}
+
+	err = kernel_getsockname(sock, buf);
+	if (err < 0) {
+		dprintk("RPC:       getsockname failed (%d)\n", err);
+		goto out_release;
+	}
+
+	err = 0;
+	if (buf->sa_family == AF_INET6) {
+		struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)buf;
+		sin6->sin6_scope_id = 0;
+	}
+	dprintk("RPC:       %s succeeded\n", __func__);
+
+out_release:
+	sock_release(sock);
+out:
+	return err;
+}
+
+/*
+ * Scraping a connected socket failed, so we don't have a useable
+ * local address.  Fallback: generate an address that will prevent
+ * the server from calling us back.
+ *
+ * Returns zero and fills in "buf" if successful; otherwise, a
+ * negative errno is returned.
+ */
+static int rpc_anyaddr(int family, struct sockaddr *buf, size_t buflen)
+{
+	switch (family) {
+	case AF_INET:
+		if (buflen < sizeof(rpc_inaddr_loopback))
+			return -EINVAL;
+		memcpy(buf, &rpc_inaddr_loopback,
+				sizeof(rpc_inaddr_loopback));
+		break;
+	case AF_INET6:
+		if (buflen < sizeof(rpc_in6addr_loopback))
+			return -EINVAL;
+		memcpy(buf, &rpc_in6addr_loopback,
+				sizeof(rpc_in6addr_loopback));
+		break;
+	default:
+		dprintk("RPC:       %s: address family not supported\n",
+			__func__);
+		return -EAFNOSUPPORT;
+	}
+	dprintk("RPC:       %s: succeeded\n", __func__);
+	return 0;
+}
+
+/**
+ * rpc_localaddr - discover local endpoint address for an RPC client
+ * @clnt: RPC client structure
+ * @buf: target buffer
+ * @buflen: size of target buffer, in bytes
+ *
+ * Returns zero and fills in "buf" and "buflen" if successful;
+ * otherwise, a negative errno is returned.
+ *
+ * This works even if the underlying transport is not currently connected,
+ * or if the upper layer never previously provided a source address.
+ *
+ * The result of this function call is transient: multiple calls in
+ * succession may give different results, depending on how local
+ * networking configuration changes over time.
+ */
+int rpc_localaddr(struct rpc_clnt *clnt, struct sockaddr *buf, size_t buflen)
+{
+	struct sockaddr_storage address;
+	struct sockaddr *sap = (struct sockaddr *)&address;
+	struct rpc_xprt *xprt;
+	struct net *net;
+	size_t salen;
+	int err;
+
+	rcu_read_lock();
+	xprt = rcu_dereference(clnt->cl_xprt);
+	salen = xprt->addrlen;
+	memcpy(sap, &xprt->addr, salen);
+	net = get_net(xprt->xprt_net);
+	rcu_read_unlock();
+
+	rpc_set_port(sap, 0);
+	err = rpc_sockname(net, sap, salen, buf);
+	put_net(net);
+	if (err != 0)
+		/* Couldn't discover local address, return ANYADDR */
+		return rpc_anyaddr(sap->sa_family, buf, buflen);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(rpc_localaddr);
+
+void
+rpc_setbufsize(struct rpc_clnt *clnt, unsigned int sndsize, unsigned int rcvsize)
+{
+	struct rpc_xprt *xprt;
+
+	rcu_read_lock();
+	xprt = rcu_dereference(clnt->cl_xprt);
+	if (xprt->ops->set_buffer_size)
+		xprt->ops->set_buffer_size(xprt, sndsize, rcvsize);
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(rpc_setbufsize);
+
+/**
+ * rpc_net_ns - Get the network namespace for this RPC client
+ * @clnt: RPC client to query
+ *
+ */
+struct net *rpc_net_ns(struct rpc_clnt *clnt)
+{
+	struct net *ret;
+
+	rcu_read_lock();
+	ret = rcu_dereference(clnt->cl_xprt)->xprt_net;
+	rcu_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rpc_net_ns);
+
+/**
+ * rpc_max_payload - Get maximum payload size for a transport, in bytes
+ * @clnt: RPC client to query
+ *
+ * For stream transports, this is one RPC record fragment (see RFC
+ * 1831), as we don't support multi-record requests yet.  For datagram
+ * transports, this is the size of an IP packet minus the IP, UDP, and
+ * RPC header sizes.
+ */
+size_t rpc_max_payload(struct rpc_clnt *clnt)
+{
+	size_t ret;
+
+	rcu_read_lock();
+	ret = rcu_dereference(clnt->cl_xprt)->max_payload;
+	rcu_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rpc_max_payload);
+
+/**
+ * rpc_max_bc_payload - Get maximum backchannel payload size, in bytes
+ * @clnt: RPC client to query
+ */
+size_t rpc_max_bc_payload(struct rpc_clnt *clnt)
+{
+	struct rpc_xprt *xprt;
+	size_t ret;
+
+	rcu_read_lock();
+	xprt = rcu_dereference(clnt->cl_xprt);
+	ret = xprt->ops->bc_maxpayload(xprt);
+	rcu_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rpc_max_bc_payload);
+
+/**
+ * rpc_force_rebind - force transport to check that remote port is unchanged
+ * @clnt: client to rebind
+ *
+ */
+void rpc_force_rebind(struct rpc_clnt *clnt)
+{
+	if (clnt->cl_autobind) {
+		rcu_read_lock();
+		xprt_clear_bound(rcu_dereference(clnt->cl_xprt));
+		rcu_read_unlock();
+	}
+}
+EXPORT_SYMBOL_GPL(rpc_force_rebind);
+
+/*
+ * Restart an (async) RPC call from the call_prepare state.
+ * Usually called from within the exit handler.
+ */
+int
+rpc_restart_call_prepare(struct rpc_task *task)
+{
+	if (RPC_ASSASSINATED(task))
+		return 0;
+	task->tk_action = call_start;
+	task->tk_status = 0;
+	if (task->tk_ops->rpc_call_prepare != NULL)
+		task->tk_action = rpc_prepare_task;
+	return 1;
+}
+EXPORT_SYMBOL_GPL(rpc_restart_call_prepare);
+
+/*
+ * Restart an (async) RPC call. Usually called from within the
+ * exit handler.
+ */
+int
+rpc_restart_call(struct rpc_task *task)
+{
+	if (RPC_ASSASSINATED(task))
+		return 0;
+	task->tk_action = call_start;
+	task->tk_status = 0;
+	return 1;
+}
+EXPORT_SYMBOL_GPL(rpc_restart_call);
+
+const char
+*rpc_proc_name(const struct rpc_task *task)
+{
+	const struct rpc_procinfo *proc = task->tk_msg.rpc_proc;
+
+	if (proc) {
+		if (proc->p_name)
+			return proc->p_name;
+		else
+			return "NULL";
+	} else
+		return "no proc";
+}
+
+/*
+ * 0.  Initial state
+ *
+ *     Other FSM states can be visited zero or more times, but
+ *     this state is visited exactly once for each RPC.
+ */
+static void
+call_start(struct rpc_task *task)
+{
+	struct rpc_clnt	*clnt = task->tk_client;
+	int idx = task->tk_msg.rpc_proc->p_statidx;
+
+	trace_rpc_request(task);
+	dprintk("RPC: %5u call_start %s%d proc %s (%s)\n", task->tk_pid,
+			clnt->cl_program->name, clnt->cl_vers,
+			rpc_proc_name(task),
+			(RPC_IS_ASYNC(task) ? "async" : "sync"));
+
+	/* Increment call count (version might not be valid for ping) */
+	if (clnt->cl_program->version[clnt->cl_vers])
+		clnt->cl_program->version[clnt->cl_vers]->counts[idx]++;
+	clnt->cl_stats->rpccnt++;
+	task->tk_action = call_reserve;
+	rpc_task_set_transport(task, clnt);
+}
+
+/*
+ * 1.	Reserve an RPC call slot
+ */
+static void
+call_reserve(struct rpc_task *task)
+{
+	dprint_status(task);
+
+	task->tk_status  = 0;
+	task->tk_action  = call_reserveresult;
+	xprt_reserve(task);
+}
+
+static void call_retry_reserve(struct rpc_task *task);
+
+/*
+ * 1b.	Grok the result of xprt_reserve()
+ */
+static void
+call_reserveresult(struct rpc_task *task)
+{
+	int status = task->tk_status;
+
+	dprint_status(task);
+
+	/*
+	 * After a call to xprt_reserve(), we must have either
+	 * a request slot or else an error status.
+	 */
+	task->tk_status = 0;
+	if (status >= 0) {
+		if (task->tk_rqstp) {
+			task->tk_action = call_refresh;
+			return;
+		}
+
+		printk(KERN_ERR "%s: status=%d, but no request slot, exiting\n",
+				__func__, status);
+		rpc_exit(task, -EIO);
+		return;
+	}
+
+	/*
+	 * Even though there was an error, we may have acquired
+	 * a request slot somehow.  Make sure not to leak it.
+	 */
+	if (task->tk_rqstp) {
+		printk(KERN_ERR "%s: status=%d, request allocated anyway\n",
+				__func__, status);
+		xprt_release(task);
+	}
+
+	switch (status) {
+	case -ENOMEM:
+		rpc_delay(task, HZ >> 2);
+		/* fall through */
+	case -EAGAIN:	/* woken up; retry */
+		task->tk_action = call_retry_reserve;
+		return;
+	case -EIO:	/* probably a shutdown */
+		break;
+	default:
+		printk(KERN_ERR "%s: unrecognized error %d, exiting\n",
+				__func__, status);
+		break;
+	}
+	rpc_exit(task, status);
+}
+
+/*
+ * 1c.	Retry reserving an RPC call slot
+ */
+static void
+call_retry_reserve(struct rpc_task *task)
+{
+	dprint_status(task);
+
+	task->tk_status  = 0;
+	task->tk_action  = call_reserveresult;
+	xprt_retry_reserve(task);
+}
+
+/*
+ * 2.	Bind and/or refresh the credentials
+ */
+static void
+call_refresh(struct rpc_task *task)
+{
+	dprint_status(task);
+
+	task->tk_action = call_refreshresult;
+	task->tk_status = 0;
+	task->tk_client->cl_stats->rpcauthrefresh++;
+	rpcauth_refreshcred(task);
+}
+
+/*
+ * 2a.	Process the results of a credential refresh
+ */
+static void
+call_refreshresult(struct rpc_task *task)
+{
+	int status = task->tk_status;
+
+	dprint_status(task);
+
+	task->tk_status = 0;
+	task->tk_action = call_refresh;
+	switch (status) {
+	case 0:
+		if (rpcauth_uptodatecred(task)) {
+			task->tk_action = call_allocate;
+			return;
+		}
+		/* Use rate-limiting and a max number of retries if refresh
+		 * had status 0 but failed to update the cred.
+		 */
+		/* fall through */
+	case -ETIMEDOUT:
+		rpc_delay(task, 3*HZ);
+		/* fall through */
+	case -EAGAIN:
+		status = -EACCES;
+		/* fall through */
+	case -EKEYEXPIRED:
+		if (!task->tk_cred_retry)
+			break;
+		task->tk_cred_retry--;
+		dprintk("RPC: %5u %s: retry refresh creds\n",
+				task->tk_pid, __func__);
+		return;
+	}
+	dprintk("RPC: %5u %s: refresh creds failed with error %d\n",
+				task->tk_pid, __func__, status);
+	rpc_exit(task, status);
+}
+
+/*
+ * 2b.	Allocate the buffer. For details, see sched.c:rpc_malloc.
+ *	(Note: buffer memory is freed in xprt_release).
+ */
+static void
+call_allocate(struct rpc_task *task)
+{
+	unsigned int slack = task->tk_rqstp->rq_cred->cr_auth->au_cslack;
+	struct rpc_rqst *req = task->tk_rqstp;
+	struct rpc_xprt *xprt = req->rq_xprt;
+	const struct rpc_procinfo *proc = task->tk_msg.rpc_proc;
+	int status;
+
+	dprint_status(task);
+
+	task->tk_status = 0;
+	task->tk_action = call_bind;
+
+	if (req->rq_buffer)
+		return;
+
+	if (proc->p_proc != 0) {
+		BUG_ON(proc->p_arglen == 0);
+		if (proc->p_decode != NULL)
+			BUG_ON(proc->p_replen == 0);
+	}
+
+	/*
+	 * Calculate the size (in quads) of the RPC call
+	 * and reply headers, and convert both values
+	 * to byte sizes.
+	 */
+	req->rq_callsize = RPC_CALLHDRSIZE + (slack << 1) + proc->p_arglen;
+	req->rq_callsize <<= 2;
+	req->rq_rcvsize = RPC_REPHDRSIZE + slack + proc->p_replen;
+	req->rq_rcvsize <<= 2;
+
+	status = xprt->ops->buf_alloc(task);
+	xprt_inject_disconnect(xprt);
+	if (status == 0)
+		return;
+	if (status != -ENOMEM) {
+		rpc_exit(task, status);
+		return;
+	}
+
+	dprintk("RPC: %5u rpc_buffer allocation failed\n", task->tk_pid);
+
+	if (RPC_IS_ASYNC(task) || !fatal_signal_pending(current)) {
+		task->tk_action = call_allocate;
+		rpc_delay(task, HZ>>4);
+		return;
+	}
+
+	rpc_exit(task, -ERESTARTSYS);
+}
+
+static inline int
+rpc_task_need_encode(struct rpc_task *task)
+{
+	return task->tk_rqstp->rq_snd_buf.len == 0;
+}
+
+static inline void
+rpc_task_force_reencode(struct rpc_task *task)
+{
+	task->tk_rqstp->rq_snd_buf.len = 0;
+	task->tk_rqstp->rq_bytes_sent = 0;
+}
+
+/*
+ * 3.	Encode arguments of an RPC call
+ */
+static void
+rpc_xdr_encode(struct rpc_task *task)
+{
+	struct rpc_rqst	*req = task->tk_rqstp;
+	kxdreproc_t	encode;
+	__be32		*p;
+
+	dprint_status(task);
+
+	xdr_buf_init(&req->rq_snd_buf,
+		     req->rq_buffer,
+		     req->rq_callsize);
+	xdr_buf_init(&req->rq_rcv_buf,
+		     req->rq_rbuffer,
+		     req->rq_rcvsize);
+
+	p = rpc_encode_header(task);
+	if (p == NULL) {
+		printk(KERN_INFO "RPC: couldn't encode RPC header, exit EIO\n");
+		rpc_exit(task, -EIO);
+		return;
+	}
+
+	encode = task->tk_msg.rpc_proc->p_encode;
+	if (encode == NULL)
+		return;
+
+	task->tk_status = rpcauth_wrap_req(task, encode, req, p,
+			task->tk_msg.rpc_argp);
+}
+
+/*
+ * 4.	Get the server port number if not yet set
+ */
+static void
+call_bind(struct rpc_task *task)
+{
+	struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
+
+	dprint_status(task);
+
+	task->tk_action = call_connect;
+	if (!xprt_bound(xprt)) {
+		task->tk_action = call_bind_status;
+		task->tk_timeout = xprt->bind_timeout;
+		xprt->ops->rpcbind(task);
+	}
+}
+
+/*
+ * 4a.	Sort out bind result
+ */
+static void
+call_bind_status(struct rpc_task *task)
+{
+	int status = -EIO;
+
+	if (task->tk_status >= 0) {
+		dprint_status(task);
+		task->tk_status = 0;
+		task->tk_action = call_connect;
+		return;
+	}
+
+	trace_rpc_bind_status(task);
+	switch (task->tk_status) {
+	case -ENOMEM:
+		dprintk("RPC: %5u rpcbind out of memory\n", task->tk_pid);
+		rpc_delay(task, HZ >> 2);
+		goto retry_timeout;
+	case -EACCES:
+		dprintk("RPC: %5u remote rpcbind: RPC program/version "
+				"unavailable\n", task->tk_pid);
+		/* fail immediately if this is an RPC ping */
+		if (task->tk_msg.rpc_proc->p_proc == 0) {
+			status = -EOPNOTSUPP;
+			break;
+		}
+		if (task->tk_rebind_retry == 0)
+			break;
+		task->tk_rebind_retry--;
+		rpc_delay(task, 3*HZ);
+		goto retry_timeout;
+	case -ETIMEDOUT:
+		dprintk("RPC: %5u rpcbind request timed out\n",
+				task->tk_pid);
+		goto retry_timeout;
+	case -EPFNOSUPPORT:
+		/* server doesn't support any rpcbind version we know of */
+		dprintk("RPC: %5u unrecognized remote rpcbind service\n",
+				task->tk_pid);
+		break;
+	case -EPROTONOSUPPORT:
+		dprintk("RPC: %5u remote rpcbind version unavailable, retrying\n",
+				task->tk_pid);
+		goto retry_timeout;
+	case -ECONNREFUSED:		/* connection problems */
+	case -ECONNRESET:
+	case -ECONNABORTED:
+	case -ENOTCONN:
+	case -EHOSTDOWN:
+	case -ENETDOWN:
+	case -EHOSTUNREACH:
+	case -ENETUNREACH:
+	case -ENOBUFS:
+	case -EPIPE:
+		dprintk("RPC: %5u remote rpcbind unreachable: %d\n",
+				task->tk_pid, task->tk_status);
+		if (!RPC_IS_SOFTCONN(task)) {
+			rpc_delay(task, 5*HZ);
+			goto retry_timeout;
+		}
+		status = task->tk_status;
+		break;
+	default:
+		dprintk("RPC: %5u unrecognized rpcbind error (%d)\n",
+				task->tk_pid, -task->tk_status);
+	}
+
+	rpc_exit(task, status);
+	return;
+
+retry_timeout:
+	task->tk_status = 0;
+	task->tk_action = call_timeout;
+}
+
+/*
+ * 4b.	Connect to the RPC server
+ */
+static void
+call_connect(struct rpc_task *task)
+{
+	struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
+
+	dprintk("RPC: %5u call_connect xprt %p %s connected\n",
+			task->tk_pid, xprt,
+			(xprt_connected(xprt) ? "is" : "is not"));
+
+	task->tk_action = call_transmit;
+	if (!xprt_connected(xprt)) {
+		task->tk_action = call_connect_status;
+		if (task->tk_status < 0)
+			return;
+		if (task->tk_flags & RPC_TASK_NOCONNECT) {
+			rpc_exit(task, -ENOTCONN);
+			return;
+		}
+		xprt_connect(task);
+	}
+}
+
+/*
+ * 4c.	Sort out connect result
+ */
+static void
+call_connect_status(struct rpc_task *task)
+{
+	struct rpc_clnt *clnt = task->tk_client;
+	int status = task->tk_status;
+
+	dprint_status(task);
+
+	trace_rpc_connect_status(task);
+	task->tk_status = 0;
+	switch (status) {
+	case -ECONNREFUSED:
+		/* A positive refusal suggests a rebind is needed. */
+		if (RPC_IS_SOFTCONN(task))
+			break;
+		if (clnt->cl_autobind) {
+			rpc_force_rebind(clnt);
+			task->tk_action = call_bind;
+			return;
+		}
+		/* fall through */
+	case -ECONNRESET:
+	case -ECONNABORTED:
+	case -ENETDOWN:
+	case -ENETUNREACH:
+	case -EHOSTUNREACH:
+	case -EADDRINUSE:
+	case -ENOBUFS:
+	case -EPIPE:
+		xprt_conditional_disconnect(task->tk_rqstp->rq_xprt,
+					    task->tk_rqstp->rq_connect_cookie);
+		if (RPC_IS_SOFTCONN(task))
+			break;
+		/* retry with existing socket, after a delay */
+		rpc_delay(task, 3*HZ);
+		/* fall through */
+	case -EAGAIN:
+		/* Check for timeouts before looping back to call_bind */
+	case -ETIMEDOUT:
+		task->tk_action = call_timeout;
+		return;
+	case 0:
+		clnt->cl_stats->netreconn++;
+		task->tk_action = call_transmit;
+		return;
+	}
+	rpc_exit(task, status);
+}
+
+/*
+ * 5.	Transmit the RPC request, and wait for reply
+ */
+static void
+call_transmit(struct rpc_task *task)
+{
+	int is_retrans = RPC_WAS_SENT(task);
+
+	dprint_status(task);
+
+	task->tk_action = call_status;
+	if (task->tk_status < 0)
+		return;
+	if (!xprt_prepare_transmit(task))
+		return;
+	task->tk_action = call_transmit_status;
+	/* Encode here so that rpcsec_gss can use correct sequence number. */
+	if (rpc_task_need_encode(task)) {
+		rpc_xdr_encode(task);
+		/* Did the encode result in an error condition? */
+		if (task->tk_status != 0) {
+			/* Was the error nonfatal? */
+			if (task->tk_status == -EAGAIN)
+				rpc_delay(task, HZ >> 4);
+			else
+				rpc_exit(task, task->tk_status);
+			return;
+		}
+	}
+	xprt_transmit(task);
+	if (task->tk_status < 0)
+		return;
+	if (is_retrans)
+		task->tk_client->cl_stats->rpcretrans++;
+	/*
+	 * On success, ensure that we call xprt_end_transmit() before sleeping
+	 * in order to allow access to the socket to other RPC requests.
+	 */
+	call_transmit_status(task);
+	if (rpc_reply_expected(task))
+		return;
+	task->tk_action = rpc_exit_task;
+	rpc_wake_up_queued_task(&task->tk_rqstp->rq_xprt->pending, task);
+}
+
+/*
+ * 5a.	Handle cleanup after a transmission
+ */
+static void
+call_transmit_status(struct rpc_task *task)
+{
+	struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
+	task->tk_action = call_status;
+
+	/*
+	 * Common case: success.  Force the compiler to put this
+	 * test first.  Or, if any error and xprt_close_wait,
+	 * release the xprt lock so the socket can close.
+	 */
+	if (task->tk_status == 0 || xprt_close_wait(xprt)) {
+		xprt_end_transmit(task);
+		rpc_task_force_reencode(task);
+		return;
+	}
+
+	switch (task->tk_status) {
+	case -EAGAIN:
+	case -ENOBUFS:
+		break;
+	default:
+		dprint_status(task);
+		xprt_end_transmit(task);
+		rpc_task_force_reencode(task);
+		break;
+		/*
+		 * Special cases: if we've been waiting on the
+		 * socket's write_space() callback, or if the
+		 * socket just returned a connection error,
+		 * then hold onto the transport lock.
+		 */
+	case -ECONNREFUSED:
+	case -EHOSTDOWN:
+	case -ENETDOWN:
+	case -EHOSTUNREACH:
+	case -ENETUNREACH:
+	case -EPERM:
+		if (RPC_IS_SOFTCONN(task)) {
+			xprt_end_transmit(task);
+			if (!task->tk_msg.rpc_proc->p_proc)
+				trace_xprt_ping(task->tk_xprt,
+						task->tk_status);
+			rpc_exit(task, task->tk_status);
+			break;
+		}
+		/* fall through */
+	case -ECONNRESET:
+	case -ECONNABORTED:
+	case -EADDRINUSE:
+	case -ENOTCONN:
+	case -EPIPE:
+		rpc_task_force_reencode(task);
+	}
+}
+
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+/*
+ * 5b.	Send the backchannel RPC reply.  On error, drop the reply.  In
+ * addition, disconnect on connectivity errors.
+ */
+static void
+call_bc_transmit(struct rpc_task *task)
+{
+	struct rpc_rqst *req = task->tk_rqstp;
+
+	if (!xprt_prepare_transmit(task))
+		goto out_retry;
+
+	if (task->tk_status < 0) {
+		printk(KERN_NOTICE "RPC: Could not send backchannel reply "
+			"error: %d\n", task->tk_status);
+		goto out_done;
+	}
+	if (req->rq_connect_cookie != req->rq_xprt->connect_cookie)
+		req->rq_bytes_sent = 0;
+
+	xprt_transmit(task);
+
+	if (task->tk_status == -EAGAIN)
+		goto out_nospace;
+
+	xprt_end_transmit(task);
+	dprint_status(task);
+	switch (task->tk_status) {
+	case 0:
+		/* Success */
+	case -ENETDOWN:
+	case -EHOSTDOWN:
+	case -EHOSTUNREACH:
+	case -ENETUNREACH:
+	case -ECONNRESET:
+	case -ECONNREFUSED:
+	case -EADDRINUSE:
+	case -ENOTCONN:
+	case -EPIPE:
+		break;
+	case -ETIMEDOUT:
+		/*
+		 * Problem reaching the server.  Disconnect and let the
+		 * forechannel reestablish the connection.  The server will
+		 * have to retransmit the backchannel request and we'll
+		 * reprocess it.  Since these ops are idempotent, there's no
+		 * need to cache our reply at this time.
+		 */
+		printk(KERN_NOTICE "RPC: Could not send backchannel reply "
+			"error: %d\n", task->tk_status);
+		xprt_conditional_disconnect(req->rq_xprt,
+			req->rq_connect_cookie);
+		break;
+	default:
+		/*
+		 * We were unable to reply and will have to drop the
+		 * request.  The server should reconnect and retransmit.
+		 */
+		WARN_ON_ONCE(task->tk_status == -EAGAIN);
+		printk(KERN_NOTICE "RPC: Could not send backchannel reply "
+			"error: %d\n", task->tk_status);
+		break;
+	}
+	rpc_wake_up_queued_task(&req->rq_xprt->pending, task);
+out_done:
+	task->tk_action = rpc_exit_task;
+	return;
+out_nospace:
+	req->rq_connect_cookie = req->rq_xprt->connect_cookie;
+out_retry:
+	task->tk_status = 0;
+}
+#endif /* CONFIG_SUNRPC_BACKCHANNEL */
+
+/*
+ * 6.	Sort out the RPC call status
+ */
+static void
+call_status(struct rpc_task *task)
+{
+	struct rpc_clnt	*clnt = task->tk_client;
+	struct rpc_rqst	*req = task->tk_rqstp;
+	int		status;
+
+	if (!task->tk_msg.rpc_proc->p_proc)
+		trace_xprt_ping(task->tk_xprt, task->tk_status);
+
+	if (req->rq_reply_bytes_recvd > 0 && !req->rq_bytes_sent)
+		task->tk_status = req->rq_reply_bytes_recvd;
+
+	dprint_status(task);
+
+	status = task->tk_status;
+	if (status >= 0) {
+		task->tk_action = call_decode;
+		return;
+	}
+
+	trace_rpc_call_status(task);
+	task->tk_status = 0;
+	switch(status) {
+	case -EHOSTDOWN:
+	case -ENETDOWN:
+	case -EHOSTUNREACH:
+	case -ENETUNREACH:
+	case -EPERM:
+		if (RPC_IS_SOFTCONN(task)) {
+			rpc_exit(task, status);
+			break;
+		}
+		/*
+		 * Delay any retries for 3 seconds, then handle as if it
+		 * were a timeout.
+		 */
+		rpc_delay(task, 3*HZ);
+		/* fall through */
+	case -ETIMEDOUT:
+		task->tk_action = call_timeout;
+		break;
+	case -ECONNREFUSED:
+	case -ECONNRESET:
+	case -ECONNABORTED:
+		rpc_force_rebind(clnt);
+		/* fall through */
+	case -EADDRINUSE:
+		rpc_delay(task, 3*HZ);
+		/* fall through */
+	case -EPIPE:
+	case -ENOTCONN:
+		task->tk_action = call_bind;
+		break;
+	case -ENOBUFS:
+		rpc_delay(task, HZ>>2);
+		/* fall through */
+	case -EAGAIN:
+		task->tk_action = call_transmit;
+		break;
+	case -EIO:
+		/* shutdown or soft timeout */
+		rpc_exit(task, status);
+		break;
+	default:
+		if (clnt->cl_chatty)
+			printk("%s: RPC call returned error %d\n",
+			       clnt->cl_program->name, -status);
+		rpc_exit(task, status);
+	}
+}
+
+/*
+ * 6a.	Handle RPC timeout
+ * 	We do not release the request slot, so we keep using the
+ *	same XID for all retransmits.
+ */
+static void
+call_timeout(struct rpc_task *task)
+{
+	struct rpc_clnt	*clnt = task->tk_client;
+
+	if (xprt_adjust_timeout(task->tk_rqstp) == 0) {
+		dprintk("RPC: %5u call_timeout (minor)\n", task->tk_pid);
+		goto retry;
+	}
+
+	dprintk("RPC: %5u call_timeout (major)\n", task->tk_pid);
+	task->tk_timeouts++;
+
+	if (RPC_IS_SOFTCONN(task)) {
+		rpc_exit(task, -ETIMEDOUT);
+		return;
+	}
+	if (RPC_IS_SOFT(task)) {
+		if (clnt->cl_chatty) {
+			printk(KERN_NOTICE "%s: server %s not responding, timed out\n",
+				clnt->cl_program->name,
+				task->tk_xprt->servername);
+		}
+		if (task->tk_flags & RPC_TASK_TIMEOUT)
+			rpc_exit(task, -ETIMEDOUT);
+		else
+			rpc_exit(task, -EIO);
+		return;
+	}
+
+	if (!(task->tk_flags & RPC_CALL_MAJORSEEN)) {
+		task->tk_flags |= RPC_CALL_MAJORSEEN;
+		if (clnt->cl_chatty) {
+			printk(KERN_NOTICE "%s: server %s not responding, still trying\n",
+			clnt->cl_program->name,
+			task->tk_xprt->servername);
+		}
+	}
+	rpc_force_rebind(clnt);
+	/*
+	 * Did our request time out due to an RPCSEC_GSS out-of-sequence
+	 * event? RFC2203 requires the server to drop all such requests.
+	 */
+	rpcauth_invalcred(task);
+
+retry:
+	task->tk_action = call_bind;
+	task->tk_status = 0;
+}
+
+/*
+ * 7.	Decode the RPC reply
+ */
+static void
+call_decode(struct rpc_task *task)
+{
+	struct rpc_clnt	*clnt = task->tk_client;
+	struct rpc_rqst	*req = task->tk_rqstp;
+	kxdrdproc_t	decode = task->tk_msg.rpc_proc->p_decode;
+	__be32		*p;
+
+	dprint_status(task);
+
+	if (task->tk_flags & RPC_CALL_MAJORSEEN) {
+		if (clnt->cl_chatty) {
+			printk(KERN_NOTICE "%s: server %s OK\n",
+				clnt->cl_program->name,
+				task->tk_xprt->servername);
+		}
+		task->tk_flags &= ~RPC_CALL_MAJORSEEN;
+	}
+
+	/*
+	 * Ensure that we see all writes made by xprt_complete_rqst()
+	 * before it changed req->rq_reply_bytes_recvd.
+	 */
+	smp_rmb();
+	req->rq_rcv_buf.len = req->rq_private_buf.len;
+
+	/* Check that the softirq receive buffer is valid */
+	WARN_ON(memcmp(&req->rq_rcv_buf, &req->rq_private_buf,
+				sizeof(req->rq_rcv_buf)) != 0);
+
+	if (req->rq_rcv_buf.len < 12) {
+		if (!RPC_IS_SOFT(task)) {
+			task->tk_action = call_bind;
+			goto out_retry;
+		}
+		dprintk("RPC:       %s: too small RPC reply size (%d bytes)\n",
+				clnt->cl_program->name, task->tk_status);
+		task->tk_action = call_timeout;
+		goto out_retry;
+	}
+
+	p = rpc_verify_header(task);
+	if (IS_ERR(p)) {
+		if (p == ERR_PTR(-EAGAIN))
+			goto out_retry;
+		return;
+	}
+
+	task->tk_action = rpc_exit_task;
+
+	if (decode) {
+		task->tk_status = rpcauth_unwrap_resp(task, decode, req, p,
+						      task->tk_msg.rpc_resp);
+	}
+	dprintk("RPC: %5u call_decode result %d\n", task->tk_pid,
+			task->tk_status);
+	return;
+out_retry:
+	task->tk_status = 0;
+	/* Note: rpc_verify_header() may have freed the RPC slot */
+	if (task->tk_rqstp == req) {
+		req->rq_reply_bytes_recvd = req->rq_rcv_buf.len = 0;
+		if (task->tk_client->cl_discrtry)
+			xprt_conditional_disconnect(req->rq_xprt,
+					req->rq_connect_cookie);
+	}
+}
+
+static __be32 *
+rpc_encode_header(struct rpc_task *task)
+{
+	struct rpc_clnt *clnt = task->tk_client;
+	struct rpc_rqst	*req = task->tk_rqstp;
+	__be32		*p = req->rq_svec[0].iov_base;
+
+	/* FIXME: check buffer size? */
+
+	p = xprt_skip_transport_header(req->rq_xprt, p);
+	*p++ = req->rq_xid;		/* XID */
+	*p++ = htonl(RPC_CALL);		/* CALL */
+	*p++ = htonl(RPC_VERSION);	/* RPC version */
+	*p++ = htonl(clnt->cl_prog);	/* program number */
+	*p++ = htonl(clnt->cl_vers);	/* program version */
+	*p++ = htonl(task->tk_msg.rpc_proc->p_proc);	/* procedure */
+	p = rpcauth_marshcred(task, p);
+	req->rq_slen = xdr_adjust_iovec(&req->rq_svec[0], p);
+	return p;
+}
+
+static __be32 *
+rpc_verify_header(struct rpc_task *task)
+{
+	struct rpc_clnt *clnt = task->tk_client;
+	struct kvec *iov = &task->tk_rqstp->rq_rcv_buf.head[0];
+	int len = task->tk_rqstp->rq_rcv_buf.len >> 2;
+	__be32	*p = iov->iov_base;
+	u32 n;
+	int error = -EACCES;
+
+	if ((task->tk_rqstp->rq_rcv_buf.len & 3) != 0) {
+		/* RFC-1014 says that the representation of XDR data must be a
+		 * multiple of four bytes
+		 * - if it isn't pointer subtraction in the NFS client may give
+		 *   undefined results
+		 */
+		dprintk("RPC: %5u %s: XDR representation not a multiple of"
+		       " 4 bytes: 0x%x\n", task->tk_pid, __func__,
+		       task->tk_rqstp->rq_rcv_buf.len);
+		error = -EIO;
+		goto out_err;
+	}
+	if ((len -= 3) < 0)
+		goto out_overflow;
+
+	p += 1; /* skip XID */
+	if ((n = ntohl(*p++)) != RPC_REPLY) {
+		dprintk("RPC: %5u %s: not an RPC reply: %x\n",
+			task->tk_pid, __func__, n);
+		error = -EIO;
+		goto out_garbage;
+	}
+
+	if ((n = ntohl(*p++)) != RPC_MSG_ACCEPTED) {
+		if (--len < 0)
+			goto out_overflow;
+		switch ((n = ntohl(*p++))) {
+		case RPC_AUTH_ERROR:
+			break;
+		case RPC_MISMATCH:
+			dprintk("RPC: %5u %s: RPC call version mismatch!\n",
+				task->tk_pid, __func__);
+			error = -EPROTONOSUPPORT;
+			goto out_err;
+		default:
+			dprintk("RPC: %5u %s: RPC call rejected, "
+				"unknown error: %x\n",
+				task->tk_pid, __func__, n);
+			error = -EIO;
+			goto out_err;
+		}
+		if (--len < 0)
+			goto out_overflow;
+		switch ((n = ntohl(*p++))) {
+		case RPC_AUTH_REJECTEDCRED:
+		case RPC_AUTH_REJECTEDVERF:
+		case RPCSEC_GSS_CREDPROBLEM:
+		case RPCSEC_GSS_CTXPROBLEM:
+			if (!task->tk_cred_retry)
+				break;
+			task->tk_cred_retry--;
+			dprintk("RPC: %5u %s: retry stale creds\n",
+					task->tk_pid, __func__);
+			rpcauth_invalcred(task);
+			/* Ensure we obtain a new XID! */
+			xprt_release(task);
+			task->tk_action = call_reserve;
+			goto out_retry;
+		case RPC_AUTH_BADCRED:
+		case RPC_AUTH_BADVERF:
+			/* possibly garbled cred/verf? */
+			if (!task->tk_garb_retry)
+				break;
+			task->tk_garb_retry--;
+			dprintk("RPC: %5u %s: retry garbled creds\n",
+					task->tk_pid, __func__);
+			task->tk_action = call_bind;
+			goto out_retry;
+		case RPC_AUTH_TOOWEAK:
+			printk(KERN_NOTICE "RPC: server %s requires stronger "
+			       "authentication.\n",
+			       task->tk_xprt->servername);
+			break;
+		default:
+			dprintk("RPC: %5u %s: unknown auth error: %x\n",
+					task->tk_pid, __func__, n);
+			error = -EIO;
+		}
+		dprintk("RPC: %5u %s: call rejected %d\n",
+				task->tk_pid, __func__, n);
+		goto out_err;
+	}
+	p = rpcauth_checkverf(task, p);
+	if (IS_ERR(p)) {
+		error = PTR_ERR(p);
+		dprintk("RPC: %5u %s: auth check failed with %d\n",
+				task->tk_pid, __func__, error);
+		goto out_garbage;		/* bad verifier, retry */
+	}
+	len = p - (__be32 *)iov->iov_base - 1;
+	if (len < 0)
+		goto out_overflow;
+	switch ((n = ntohl(*p++))) {
+	case RPC_SUCCESS:
+		return p;
+	case RPC_PROG_UNAVAIL:
+		dprintk("RPC: %5u %s: program %u is unsupported "
+				"by server %s\n", task->tk_pid, __func__,
+				(unsigned int)clnt->cl_prog,
+				task->tk_xprt->servername);
+		error = -EPFNOSUPPORT;
+		goto out_err;
+	case RPC_PROG_MISMATCH:
+		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,
+				task->tk_xprt->servername);
+		error = -EPROTONOSUPPORT;
+		goto out_err;
+	case RPC_PROC_UNAVAIL:
+		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,
+				task->tk_xprt->servername);
+		error = -EOPNOTSUPP;
+		goto out_err;
+	case RPC_GARBAGE_ARGS:
+		dprintk("RPC: %5u %s: server saw garbage\n",
+				task->tk_pid, __func__);
+		break;			/* retry */
+	default:
+		dprintk("RPC: %5u %s: server accept status: %x\n",
+				task->tk_pid, __func__, n);
+		/* Also retry */
+	}
+
+out_garbage:
+	clnt->cl_stats->rpcgarbage++;
+	if (task->tk_garb_retry) {
+		task->tk_garb_retry--;
+		dprintk("RPC: %5u %s: retrying\n",
+				task->tk_pid, __func__);
+		task->tk_action = call_bind;
+out_retry:
+		return ERR_PTR(-EAGAIN);
+	}
+out_err:
+	rpc_exit(task, error);
+	dprintk("RPC: %5u %s: call failed with error %d\n", task->tk_pid,
+			__func__, error);
+	return ERR_PTR(error);
+out_overflow:
+	dprintk("RPC: %5u %s: server reply was truncated.\n", task->tk_pid,
+			__func__);
+	goto out_garbage;
+}
+
+static void rpcproc_encode_null(struct rpc_rqst *rqstp, struct xdr_stream *xdr,
+		const void *obj)
+{
+}
+
+static int rpcproc_decode_null(struct rpc_rqst *rqstp, struct xdr_stream *xdr,
+		void *obj)
+{
+	return 0;
+}
+
+static const struct rpc_procinfo rpcproc_null = {
+	.p_encode = rpcproc_encode_null,
+	.p_decode = rpcproc_decode_null,
+};
+
+static int rpc_ping(struct rpc_clnt *clnt)
+{
+	struct rpc_message msg = {
+		.rpc_proc = &rpcproc_null,
+	};
+	int err;
+	msg.rpc_cred = authnull_ops.lookup_cred(NULL, NULL, 0);
+	err = rpc_call_sync(clnt, &msg, RPC_TASK_SOFT | RPC_TASK_SOFTCONN);
+	put_rpccred(msg.rpc_cred);
+	return err;
+}
+
+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,
+		.rpc_cred = cred,
+	};
+	struct rpc_task_setup task_setup_data = {
+		.rpc_client = clnt,
+		.rpc_xprt = xprt,
+		.rpc_message = &msg,
+		.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);
+}
+
+static const 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_setup_test_and_add_xprt()
+ *
+ * This is an rpc_clnt_add_xprt setup() function which returns 1 so:
+ *   1) caller of the test function must dereference the rpc_xprt_switch
+ *   and the rpc_xprt.
+ *   2) test function must call rpc_xprt_switch_add_xprt, usually in
+ *   the rpc_call_done routine.
+ *
+ * Upon success (return of 1), the test function adds the new
+ * transport to the rpc_clnt xprt switch
+ *
+ * @clnt: struct rpc_clnt to get the new transport
+ * @xps:  the rpc_xprt_switch to hold the new transport
+ * @xprt: the rpc_xprt to test
+ * @data: a struct rpc_add_xprt_test pointer that holds the test function
+ *        and test function call data
+ */
+int rpc_clnt_setup_test_and_add_xprt(struct rpc_clnt *clnt,
+				     struct rpc_xprt_switch *xps,
+				     struct rpc_xprt *xprt,
+				     void *data)
+{
+	struct rpc_cred *cred;
+	struct rpc_task *task;
+	struct rpc_add_xprt_test *xtest = (struct rpc_add_xprt_test *)data;
+	int status = -EADDRINUSE;
+
+	xprt = xprt_get(xprt);
+	xprt_switch_get(xps);
+
+	if (rpc_xprt_switch_has_addr(xps, (struct sockaddr *)&xprt->addr))
+		goto out_err;
+
+	/* Test the connection */
+	cred = authnull_ops.lookup_cred(NULL, NULL, 0);
+	task = rpc_call_null_helper(clnt, xprt, cred,
+				    RPC_TASK_SOFT | RPC_TASK_SOFTCONN,
+				    NULL, NULL);
+	put_rpccred(cred);
+	if (IS_ERR(task)) {
+		status = PTR_ERR(task);
+		goto out_err;
+	}
+	status = task->tk_status;
+	rpc_put_task(task);
+
+	if (status < 0)
+		goto out_err;
+
+	/* rpc_xprt_switch and rpc_xprt are deferrenced by add_xprt_test() */
+	xtest->add_xprt_test(clnt, xprt, xtest->data);
+
+	/* so that rpc_clnt_add_xprt does not call rpc_xprt_switch_add_xprt */
+	return 1;
+out_err:
+	xprt_put(xprt);
+	xprt_switch_put(xps);
+	pr_info("RPC:   rpc_clnt_test_xprt failed: %d addr %s not added\n",
+		status, xprt->address_strings[RPC_DISPLAY_ADDR]);
+	return status;
+}
+EXPORT_SYMBOL_GPL(rpc_clnt_setup_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 long connect_timeout;
+	unsigned long reconnect_timeout;
+	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();
+		xprt_switch_put(xps);
+		return -EAGAIN;
+	}
+	resvport = xprt->resvport;
+	connect_timeout = xprt->connect_timeout;
+	reconnect_timeout = xprt->max_reconnect_timeout;
+	rcu_read_unlock();
+
+	xprt = xprt_create_transport(xprtargs);
+	if (IS_ERR(xprt)) {
+		ret = PTR_ERR(xprt);
+		goto out_put_switch;
+	}
+	xprt->resvport = resvport;
+	if (xprt->ops->set_connect_timeout != NULL)
+		xprt->ops->set_connect_timeout(xprt,
+				connect_timeout,
+				reconnect_timeout);
+
+	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);
+
+struct connect_timeout_data {
+	unsigned long connect_timeout;
+	unsigned long reconnect_timeout;
+};
+
+static int
+rpc_xprt_set_connect_timeout(struct rpc_clnt *clnt,
+		struct rpc_xprt *xprt,
+		void *data)
+{
+	struct connect_timeout_data *timeo = data;
+
+	if (xprt->ops->set_connect_timeout)
+		xprt->ops->set_connect_timeout(xprt,
+				timeo->connect_timeout,
+				timeo->reconnect_timeout);
+	return 0;
+}
+
+void
+rpc_set_connect_timeout(struct rpc_clnt *clnt,
+		unsigned long connect_timeout,
+		unsigned long reconnect_timeout)
+{
+	struct connect_timeout_data timeout = {
+		.connect_timeout = connect_timeout,
+		.reconnect_timeout = reconnect_timeout,
+	};
+	rpc_clnt_iterate_for_each_xprt(clnt,
+			rpc_xprt_set_connect_timeout,
+			&timeout);
+}
+EXPORT_SYMBOL_GPL(rpc_set_connect_timeout);
+
+void rpc_clnt_xprt_switch_put(struct rpc_clnt *clnt)
+{
+	rcu_read_lock();
+	xprt_switch_put(rcu_dereference(clnt->cl_xpi.xpi_xpswitch));
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(rpc_clnt_xprt_switch_put);
+
+void rpc_clnt_xprt_switch_add_xprt(struct rpc_clnt *clnt, struct rpc_xprt *xprt)
+{
+	rcu_read_lock();
+	rpc_xprt_switch_add_xprt(rcu_dereference(clnt->cl_xpi.xpi_xpswitch),
+				 xprt);
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(rpc_clnt_xprt_switch_add_xprt);
+
+bool rpc_clnt_xprt_switch_has_addr(struct rpc_clnt *clnt,
+				   const struct sockaddr *sap)
+{
+	struct rpc_xprt_switch *xps;
+	bool ret;
+
+	rcu_read_lock();
+	xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch);
+	ret = rpc_xprt_switch_has_addr(xps, sap);
+	rcu_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rpc_clnt_xprt_switch_has_addr);
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+static void rpc_show_header(void)
+{
+	printk(KERN_INFO "-pid- flgs status -client- --rqstp- "
+		"-timeout ---ops--\n");
+}
+
+static void rpc_show_task(const struct rpc_clnt *clnt,
+			  const struct rpc_task *task)
+{
+	const char *rpc_waitq = "none";
+
+	if (RPC_IS_QUEUED(task))
+		rpc_waitq = rpc_qname(task->tk_waitqueue);
+
+	printk(KERN_INFO "%5u %04x %6d %8p %8p %8ld %8p %sv%u %s a:%ps q:%s\n",
+		task->tk_pid, task->tk_flags, task->tk_status,
+		clnt, task->tk_rqstp, task->tk_timeout, task->tk_ops,
+		clnt->cl_program->name, clnt->cl_vers, rpc_proc_name(task),
+		task->tk_action, rpc_waitq);
+}
+
+void rpc_show_tasks(struct net *net)
+{
+	struct rpc_clnt *clnt;
+	struct rpc_task *task;
+	int header = 0;
+	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+	spin_lock(&sn->rpc_client_lock);
+	list_for_each_entry(clnt, &sn->all_clients, cl_clients) {
+		spin_lock(&clnt->cl_lock);
+		list_for_each_entry(task, &clnt->cl_tasks, tk_task) {
+			if (!header) {
+				rpc_show_header();
+				header++;
+			}
+			rpc_show_task(clnt, task);
+		}
+		spin_unlock(&clnt->cl_lock);
+	}
+	spin_unlock(&sn->rpc_client_lock);
+}
+#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)
+{
+	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)
+{
+	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 */