/*

   *  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)
  ", 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
  ", 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
  ",
  				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
  ", __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)
  ",

  				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)
  ",

  			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
  ", __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
  ",
  			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
  ", 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
  ", 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
  ", 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
  ",

  			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
  ",

  			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)
  ", 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_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 */
  		spin_lock(&clnt->cl_lock);
  		list_del(&task->tk_task);
  		spin_unlock(&clnt->cl_lock);
  		task->tk_client = NULL;
  
  		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) {

  		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)
  			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
  ", 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
  ", 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, int buflen)
  {
  	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)
  ", 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)
  ", err);
  		goto out_release;
  	}
  
  	err = kernel_connect(sock, sap, salen, 0);
  	if (err < 0) {
  		dprintk("RPC:       can't connect UDP socket (%d)
  ", err);
  		goto out_release;
  	}
  
  	err = kernel_getsockname(sock, buf, &buflen);
  	if (err < 0) {
  		dprintk("RPC:       getsockname failed (%d)
  ", 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
  ", __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
  ",
  			__func__);
  		return -EAFNOSUPPORT;
  	}
  	dprintk("RPC:       %s: succeeded
  ", __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, buflen);
  	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_protocol - Get transport protocol number for an RPC client
   * @clnt: RPC client to query
   *
   */
  int rpc_protocol(struct rpc_clnt *clnt)
  {
  	int protocol;
  
  	rcu_read_lock();
  	protocol = rcu_dereference(clnt->cl_xprt)->prot;
  	rcu_read_unlock();
  	return protocol;
  }
  EXPORT_SYMBOL_GPL(rpc_protocol);
  
  /**
   * 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)
  ", 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;
  }
  
  /*
   * 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
  ",

  				__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
  ",

  				__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
  ",

  				__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
  ",
  				task->tk_pid, __func__);
  		return;

  	}

  	dprintk("RPC: %5u %s: refresh creds failed with error %d
  ",
  				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
  ", 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
  ");

  		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);