/* client.c: NFS client sharing and management code
   *
   * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version
   * 2 of the License, or (at your option) any later version.
   */

  #include <linux/module.h>
  #include <linux/init.h>

  #include <linux/sched.h>

  #include <linux/time.h>
  #include <linux/kernel.h>
  #include <linux/mm.h>
  #include <linux/string.h>
  #include <linux/stat.h>
  #include <linux/errno.h>
  #include <linux/unistd.h>
  #include <linux/sunrpc/clnt.h>
  #include <linux/sunrpc/stats.h>
  #include <linux/sunrpc/metrics.h>

  #include <linux/sunrpc/xprtsock.h>

  #include <linux/sunrpc/xprtrdma.h>

  #include <linux/nfs_fs.h>
  #include <linux/nfs_mount.h>
  #include <linux/nfs4_mount.h>
  #include <linux/lockd/bind.h>

  #include <linux/seq_file.h>
  #include <linux/mount.h>
  #include <linux/nfs_idmap.h>
  #include <linux/vfs.h>
  #include <linux/inet.h>

  #include <linux/in6.h>

  #include <linux/slab.h>

  #include <net/ipv6.h>

  #include <linux/nfs_xdr.h>

  #include <linux/sunrpc/bc_xprt.h>

  
  #include <asm/system.h>
  
  #include "nfs4_fs.h"
  #include "callback.h"
  #include "delegation.h"
  #include "iostat.h"
  #include "internal.h"

  #include "fscache.h"

  #include "pnfs.h"

  
  #define NFSDBG_FACILITY		NFSDBG_CLIENT
  
  static DEFINE_SPINLOCK(nfs_client_lock);
  static LIST_HEAD(nfs_client_list);

  static LIST_HEAD(nfs_volume_list);

  static DECLARE_WAIT_QUEUE_HEAD(nfs_client_active_wq);

  #ifdef CONFIG_NFS_V4
  static DEFINE_IDR(cb_ident_idr); /* Protected by nfs_client_lock */
  
  /*
   * Get a unique NFSv4.0 callback identifier which will be used
   * by the V4.0 callback service to lookup the nfs_client struct
   */
  static int nfs_get_cb_ident_idr(struct nfs_client *clp, int minorversion)
  {
  	int ret = 0;
  
  	if (clp->rpc_ops->version != 4 || minorversion != 0)
  		return ret;
  retry:
  	if (!idr_pre_get(&cb_ident_idr, GFP_KERNEL))
  		return -ENOMEM;
  	spin_lock(&nfs_client_lock);
  	ret = idr_get_new(&cb_ident_idr, clp, &clp->cl_cb_ident);
  	spin_unlock(&nfs_client_lock);
  	if (ret == -EAGAIN)
  		goto retry;
  	return ret;
  }
  #endif /* CONFIG_NFS_V4 */

  
  /*

   * Turn off NFSv4 uid/gid mapping when using AUTH_SYS
   */

  static bool nfs4_disable_idmapping = true;

  
  /*

   * RPC cruft for NFS
   */
  static struct rpc_version *nfs_version[5] = {
  	[2]			= &nfs_version2,
  #ifdef CONFIG_NFS_V3
  	[3]			= &nfs_version3,
  #endif
  #ifdef CONFIG_NFS_V4
  	[4]			= &nfs_version4,
  #endif
  };
  
  struct rpc_program nfs_program = {
  	.name			= "nfs",
  	.number			= NFS_PROGRAM,
  	.nrvers			= ARRAY_SIZE(nfs_version),
  	.version		= nfs_version,
  	.stats			= &nfs_rpcstat,

  	.pipe_dir_name		= NFS_PIPE_DIRNAME,

  };
  
  struct rpc_stat nfs_rpcstat = {
  	.program		= &nfs_program
  };
  
  
  #ifdef CONFIG_NFS_V3_ACL
  static struct rpc_stat		nfsacl_rpcstat = { &nfsacl_program };
  static struct rpc_version *	nfsacl_version[] = {
  	[3]			= &nfsacl_version3,
  };
  
  struct rpc_program		nfsacl_program = {
  	.name			= "nfsacl",
  	.number			= NFS_ACL_PROGRAM,
  	.nrvers			= ARRAY_SIZE(nfsacl_version),
  	.version		= nfsacl_version,
  	.stats			= &nfsacl_rpcstat,
  };
  #endif  /* CONFIG_NFS_V3_ACL */

  struct nfs_client_initdata {
  	const char *hostname;

  	const struct sockaddr *addr;

  	size_t addrlen;

  	const struct nfs_rpc_ops *rpc_ops;

  	int proto;

  	u32 minorversion;

  };

  /*

   * Allocate a shared client record
   *
   * Since these are allocated/deallocated very rarely, we don't
   * bother putting them in a slab cache...
   */

  static struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_init)

  {
  	struct nfs_client *clp;

  	struct rpc_cred *cred;

  	int err = -ENOMEM;

  
  	if ((clp = kzalloc(sizeof(*clp), GFP_KERNEL)) == NULL)
  		goto error_0;

  	clp->rpc_ops = cl_init->rpc_ops;

  	atomic_set(&clp->cl_count, 1);
  	clp->cl_cons_state = NFS_CS_INITING;

  	memcpy(&clp->cl_addr, cl_init->addr, cl_init->addrlen);
  	clp->cl_addrlen = cl_init->addrlen;

  	if (cl_init->hostname) {

  		err = -ENOMEM;

  		clp->cl_hostname = kstrdup(cl_init->hostname, GFP_KERNEL);

  		if (!clp->cl_hostname)

  			goto error_cleanup;

  	}
  
  	INIT_LIST_HEAD(&clp->cl_superblocks);
  	clp->cl_rpcclient = ERR_PTR(-EINVAL);

  	clp->cl_proto = cl_init->proto;

  #ifdef CONFIG_NFS_V4

  	err = nfs_get_cb_ident_idr(clp, cl_init->minorversion);
  	if (err)
  		goto error_cleanup;

  	spin_lock_init(&clp->cl_lock);

  	INIT_DELAYED_WORK(&clp->cl_renewd, nfs4_renew_state);

  	rpc_init_wait_queue(&clp->cl_rpcwaitq, "NFS client");
  	clp->cl_boot_time = CURRENT_TIME;
  	clp->cl_state = 1 << NFS4CLNT_LEASE_EXPIRED;

  	clp->cl_minorversion = cl_init->minorversion;

  	clp->cl_mvops = nfs_v4_minor_ops[cl_init->minorversion];

  #endif

  	cred = rpc_lookup_machine_cred("*");

  	if (!IS_ERR(cred))
  		clp->cl_machine_cred = cred;

  	nfs_fscache_get_client_cookie(clp);

  	return clp;

  error_cleanup:

  	kfree(clp);
  error_0:

  	return ERR_PTR(err);

  }

  #ifdef CONFIG_NFS_V4

  #ifdef CONFIG_NFS_V4_1

  static void nfs4_shutdown_session(struct nfs_client *clp)
  {
  	if (nfs4_has_session(clp))

  		nfs4_destroy_session(clp->cl_session);

  }

  #else /* CONFIG_NFS_V4_1 */
  static void nfs4_shutdown_session(struct nfs_client *clp)
  {
  }
  #endif /* CONFIG_NFS_V4_1 */

  /*
   * Destroy the NFS4 callback service
   */
  static void nfs4_destroy_callback(struct nfs_client *clp)
  {
  	if (__test_and_clear_bit(NFS_CS_CALLBACK, &clp->cl_res_state))

  		nfs_callback_down(clp->cl_mvops->minor_version);

  }
  
  static void nfs4_shutdown_client(struct nfs_client *clp)
  {
  	if (__test_and_clear_bit(NFS_CS_RENEWD, &clp->cl_res_state))
  		nfs4_kill_renewd(clp);

  	nfs4_shutdown_session(clp);

  	nfs4_destroy_callback(clp);

  	if (__test_and_clear_bit(NFS_CS_IDMAP, &clp->cl_res_state))
  		nfs_idmap_delete(clp);
  
  	rpc_destroy_wait_queue(&clp->cl_rpcwaitq);

  }

  
  /* idr_remove_all is not needed as all id's are removed by nfs_put_client */
  void nfs_cleanup_cb_ident_idr(void)
  {
  	idr_destroy(&cb_ident_idr);
  }
  
  /* nfs_client_lock held */
  static void nfs_cb_idr_remove_locked(struct nfs_client *clp)
  {
  	if (clp->cl_cb_ident)
  		idr_remove(&cb_ident_idr, clp->cl_cb_ident);
  }

  static void pnfs_init_server(struct nfs_server *server)
  {
  	rpc_init_wait_queue(&server->roc_rpcwaitq, "pNFS ROC");
  }

  static void nfs4_destroy_server(struct nfs_server *server)
  {
  	nfs4_purge_state_owners(server);
  }

  #else
  static void nfs4_shutdown_client(struct nfs_client *clp)
  {
  }

  
  void nfs_cleanup_cb_ident_idr(void)
  {
  }
  
  static void nfs_cb_idr_remove_locked(struct nfs_client *clp)
  {
  }

  
  static void pnfs_init_server(struct nfs_server *server)
  {
  }

  #endif /* CONFIG_NFS_V4 */

  
  /*

   * Destroy a shared client record
   */
  static void nfs_free_client(struct nfs_client *clp)
  {

  	dprintk("--> nfs_free_client(%u)
  ", clp->rpc_ops->version);

  	nfs4_shutdown_client(clp);

  	nfs_fscache_release_client_cookie(clp);

  	/* -EIO all pending I/O */
  	if (!IS_ERR(clp->cl_rpcclient))
  		rpc_shutdown_client(clp->cl_rpcclient);

  	if (clp->cl_machine_cred != NULL)
  		put_rpccred(clp->cl_machine_cred);

  	nfs4_deviceid_purge_client(clp);

  	kfree(clp->cl_hostname);

  	kfree(clp->server_scope);

  	kfree(clp);
  
  	dprintk("<-- nfs_free_client()
  ");
  }
  
  /*
   * Release a reference to a shared client record
   */
  void nfs_put_client(struct nfs_client *clp)
  {

  	if (!clp)
  		return;

  	dprintk("--> nfs_put_client({%d})
  ", atomic_read(&clp->cl_count));
  
  	if (atomic_dec_and_lock(&clp->cl_count, &nfs_client_lock)) {
  		list_del(&clp->cl_share_link);

  		nfs_cb_idr_remove_locked(clp);

  		spin_unlock(&nfs_client_lock);
  
  		BUG_ON(!list_empty(&clp->cl_superblocks));
  
  		nfs_free_client(clp);
  	}
  }

  EXPORT_SYMBOL_GPL(nfs_put_client);

  #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)

  /*
   * Test if two ip6 socket addresses refer to the same socket by
   * comparing relevant fields. The padding bytes specifically, are not
   * compared. sin6_flowinfo is not compared because it only affects QoS
   * and sin6_scope_id is only compared if the address is "link local"
   * because "link local" addresses need only be unique to a specific
   * link. Conversely, ordinary unicast addresses might have different
   * sin6_scope_id.
   *
   * The caller should ensure both socket addresses are AF_INET6.
   */

  static int nfs_sockaddr_match_ipaddr6(const struct sockaddr *sa1,
  				      const struct sockaddr *sa2)

  {

  	const struct sockaddr_in6 *sin1 = (const struct sockaddr_in6 *)sa1;
  	const struct sockaddr_in6 *sin2 = (const struct sockaddr_in6 *)sa2;

  	if (!ipv6_addr_equal(&sin1->sin6_addr, &sin2->sin6_addr))

  		return 0;

  	else if (ipv6_addr_type(&sin1->sin6_addr) & IPV6_ADDR_LINKLOCAL)
  		return sin1->sin6_scope_id == sin2->sin6_scope_id;

  	return 1;

  }

  #else	/* !defined(CONFIG_IPV6) && !defined(CONFIG_IPV6_MODULE) */
  static int nfs_sockaddr_match_ipaddr6(const struct sockaddr *sa1,
  				      const struct sockaddr *sa2)

  {
  	return 0;
  }

  #endif

  /*

   * Test if two ip4 socket addresses refer to the same socket, by
   * comparing relevant fields. The padding bytes specifically, are
   * not compared.
   *
   * The caller should ensure both socket addresses are AF_INET.
   */

  static int nfs_sockaddr_match_ipaddr4(const struct sockaddr *sa1,
  				      const struct sockaddr *sa2)
  {
  	const struct sockaddr_in *sin1 = (const struct sockaddr_in *)sa1;
  	const struct sockaddr_in *sin2 = (const struct sockaddr_in *)sa2;
  
  	return sin1->sin_addr.s_addr == sin2->sin_addr.s_addr;
  }
  
  static int nfs_sockaddr_cmp_ip6(const struct sockaddr *sa1,
  				const struct sockaddr *sa2)
  {
  	const struct sockaddr_in6 *sin1 = (const struct sockaddr_in6 *)sa1;
  	const struct sockaddr_in6 *sin2 = (const struct sockaddr_in6 *)sa2;
  
  	return nfs_sockaddr_match_ipaddr6(sa1, sa2) &&
  		(sin1->sin6_port == sin2->sin6_port);
  }

  static int nfs_sockaddr_cmp_ip4(const struct sockaddr *sa1,
  				const struct sockaddr *sa2)

  {

  	const struct sockaddr_in *sin1 = (const struct sockaddr_in *)sa1;
  	const struct sockaddr_in *sin2 = (const struct sockaddr_in *)sa2;

  	return nfs_sockaddr_match_ipaddr4(sa1, sa2) &&
  		(sin1->sin_port == sin2->sin_port);
  }
  
  /*
   * Test if two socket addresses represent the same actual socket,
   * by comparing (only) relevant fields, excluding the port number.
   */
  static int nfs_sockaddr_match_ipaddr(const struct sockaddr *sa1,
  				     const struct sockaddr *sa2)
  {
  	if (sa1->sa_family != sa2->sa_family)

  		return 0;

  
  	switch (sa1->sa_family) {
  	case AF_INET:
  		return nfs_sockaddr_match_ipaddr4(sa1, sa2);
  	case AF_INET6:
  		return nfs_sockaddr_match_ipaddr6(sa1, sa2);
  	}
  	return 0;

  }
  
  /*

   * Test if two socket addresses represent the same actual socket,

   * by comparing (only) relevant fields, including the port number.

   */
  static int nfs_sockaddr_cmp(const struct sockaddr *sa1,
  			    const struct sockaddr *sa2)
  {
  	if (sa1->sa_family != sa2->sa_family)
  		return 0;
  
  	switch (sa1->sa_family) {
  	case AF_INET:

  		return nfs_sockaddr_cmp_ip4(sa1, sa2);

  	case AF_INET6:

  		return nfs_sockaddr_cmp_ip6(sa1, sa2);

  	}
  	return 0;
  }

  /* Common match routine for v4.0 and v4.1 callback services */
  bool
  nfs4_cb_match_client(const struct sockaddr *addr, struct nfs_client *clp,
  		     u32 minorversion)

  {

  	struct sockaddr *clap = (struct sockaddr *)&clp->cl_addr;

  	/* Don't match clients that failed to initialise */
  	if (!(clp->cl_cons_state == NFS_CS_READY ||
  	    clp->cl_cons_state == NFS_CS_SESSION_INITING))
  		return false;

  	/* Match the version and minorversion */
  	if (clp->rpc_ops->version != 4 ||
  	    clp->cl_minorversion != minorversion)
  		return false;

  	/* Match only the IP address, not the port number */
  	if (!nfs_sockaddr_match_ipaddr(addr, clap))
  		return false;

  	return true;

  }
  
  /*

   * Find an nfs_client on the list that matches the initialisation data
   * that is supplied.

   */

  static struct nfs_client *nfs_match_client(const struct nfs_client_initdata *data)

  {
  	struct nfs_client *clp;

  	const struct sockaddr *sap = data->addr;

  	list_for_each_entry(clp, &nfs_client_list, cl_share_link) {

  	        const struct sockaddr *clap = (struct sockaddr *)&clp->cl_addr;

  		/* Don't match clients that failed to initialise properly */
  		if (clp->cl_cons_state < 0)
  			continue;
  
  		/* Different NFS versions cannot share the same nfs_client */

  		if (clp->rpc_ops != data->rpc_ops)

  			continue;

  		if (clp->cl_proto != data->proto)
  			continue;

  		/* Match nfsv4 minorversion */
  		if (clp->cl_minorversion != data->minorversion)
  			continue;

  		/* Match the full socket address */

  		if (!nfs_sockaddr_cmp(sap, clap))

  			continue;
  
  		atomic_inc(&clp->cl_count);
  		return clp;

  	}

  	return NULL;

  }
  
  /*
   * Look up a client by IP address and protocol version
   * - creates a new record if one doesn't yet exist
   */

  static struct nfs_client *
  nfs_get_client(const struct nfs_client_initdata *cl_init,
  	       const struct rpc_timeout *timeparms,
  	       const char *ip_addr,
  	       rpc_authflavor_t authflavour,
  	       int noresvport)

  {
  	struct nfs_client *clp, *new = NULL;
  	int error;

  	dprintk("--> nfs_get_client(%s,v%u)
  ",
  		cl_init->hostname ?: "", cl_init->rpc_ops->version);

  
  	/* see if the client already exists */
  	do {
  		spin_lock(&nfs_client_lock);

  		clp = nfs_match_client(cl_init);

  		if (clp)
  			goto found_client;
  		if (new)
  			goto install_client;
  
  		spin_unlock(&nfs_client_lock);

  		new = nfs_alloc_client(cl_init);

  	} while (!IS_ERR(new));

  	dprintk("--> nfs_get_client() = %ld [failed]
  ", PTR_ERR(new));
  	return new;

  
  	/* install a new client and return with it unready */
  install_client:
  	clp = new;
  	list_add(&clp->cl_share_link, &nfs_client_list);
  	spin_unlock(&nfs_client_lock);

  
  	error = cl_init->rpc_ops->init_client(clp, timeparms, ip_addr,
  					      authflavour, noresvport);
  	if (error < 0) {
  		nfs_put_client(clp);
  		return ERR_PTR(error);
  	}

  	dprintk("--> nfs_get_client() = %p [new]
  ", clp);
  	return clp;
  
  	/* found an existing client
  	 * - make sure it's ready before returning
  	 */
  found_client:
  	spin_unlock(&nfs_client_lock);
  
  	if (new)
  		nfs_free_client(new);

  	error = wait_event_killable(nfs_client_active_wq,

  				clp->cl_cons_state < NFS_CS_INITING);

  	if (error < 0) {
  		nfs_put_client(clp);
  		return ERR_PTR(-ERESTARTSYS);

  	}
  
  	if (clp->cl_cons_state < NFS_CS_READY) {
  		error = clp->cl_cons_state;
  		nfs_put_client(clp);
  		return ERR_PTR(error);
  	}

  	BUG_ON(clp->cl_cons_state != NFS_CS_READY);

  	dprintk("--> nfs_get_client() = %p [share]
  ", clp);
  	return clp;
  }
  
  /*
   * Mark a server as ready or failed
   */

  void nfs_mark_client_ready(struct nfs_client *clp, int state)

  {
  	clp->cl_cons_state = state;
  	wake_up_all(&nfs_client_active_wq);
  }

  
  /*

   * With sessions, the client is not marked ready until after a
   * successful EXCHANGE_ID and CREATE_SESSION.
   *
   * Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
   * other versions of NFS can be tried.
   */
  int nfs4_check_client_ready(struct nfs_client *clp)
  {
  	if (!nfs4_has_session(clp))
  		return 0;
  	if (clp->cl_cons_state < NFS_CS_READY)
  		return -EPROTONOSUPPORT;
  	return 0;
  }
  
  /*

   * Initialise the timeout values for a connection
   */
  static void nfs_init_timeout_values(struct rpc_timeout *to, int proto,
  				    unsigned int timeo, unsigned int retrans)
  {
  	to->to_initval = timeo * HZ / 10;
  	to->to_retries = retrans;

  
  	switch (proto) {

  	case XPRT_TRANSPORT_TCP:

  	case XPRT_TRANSPORT_RDMA:

  		if (to->to_retries == 0)
  			to->to_retries = NFS_DEF_TCP_RETRANS;

  		if (to->to_initval == 0)

  			to->to_initval = NFS_DEF_TCP_TIMEO * HZ / 10;

  		if (to->to_initval > NFS_MAX_TCP_TIMEOUT)
  			to->to_initval = NFS_MAX_TCP_TIMEOUT;
  		to->to_increment = to->to_initval;
  		to->to_maxval = to->to_initval + (to->to_increment * to->to_retries);

  		if (to->to_maxval > NFS_MAX_TCP_TIMEOUT)
  			to->to_maxval = NFS_MAX_TCP_TIMEOUT;
  		if (to->to_maxval < to->to_initval)
  			to->to_maxval = to->to_initval;

  		to->to_exponential = 0;
  		break;

  	case XPRT_TRANSPORT_UDP:

  		if (to->to_retries == 0)
  			to->to_retries = NFS_DEF_UDP_RETRANS;

  		if (!to->to_initval)

  			to->to_initval = NFS_DEF_UDP_TIMEO * HZ / 10;

  		if (to->to_initval > NFS_MAX_UDP_TIMEOUT)
  			to->to_initval = NFS_MAX_UDP_TIMEOUT;
  		to->to_maxval = NFS_MAX_UDP_TIMEOUT;
  		to->to_exponential = 1;
  		break;

  	default:
  		BUG();

  	}
  }
  
  /*
   * Create an RPC client handle
   */

  static int nfs_create_rpc_client(struct nfs_client *clp,

  				 const struct rpc_timeout *timeparms,
  				 rpc_authflavor_t flavor,

  				 int discrtry, int noresvport)

  {

  	struct rpc_clnt		*clnt = NULL;

  	struct rpc_create_args args = {

  		.net		= &init_net,

  		.protocol	= clp->cl_proto,

  		.address	= (struct sockaddr *)&clp->cl_addr,

  		.addrsize	= clp->cl_addrlen,

  		.timeout	= timeparms,

  		.servername	= clp->cl_hostname,
  		.program	= &nfs_program,
  		.version	= clp->rpc_ops->version,
  		.authflavor	= flavor,
  	};

  	if (discrtry)
  		args.flags |= RPC_CLNT_CREATE_DISCRTRY;
  	if (noresvport)
  		args.flags |= RPC_CLNT_CREATE_NONPRIVPORT;

  	if (!IS_ERR(clp->cl_rpcclient))
  		return 0;

  	clnt = rpc_create(&args);

  	if (IS_ERR(clnt)) {
  		dprintk("%s: cannot create RPC client. Error = %ld
  ",

  				__func__, PTR_ERR(clnt));

  		return PTR_ERR(clnt);
  	}

  	clp->cl_rpcclient = clnt;
  	return 0;
  }

  
  /*
   * Version 2 or 3 client destruction
   */
  static void nfs_destroy_server(struct nfs_server *server)
  {

  	if (!(server->flags & NFS_MOUNT_LOCAL_FLOCK) ||
  			!(server->flags & NFS_MOUNT_LOCAL_FCNTL))

  		nlmclnt_done(server->nlm_host);

  }
  
  /*
   * Version 2 or 3 lockd setup
   */
  static int nfs_start_lockd(struct nfs_server *server)
  {

  	struct nlm_host *host;
  	struct nfs_client *clp = server->nfs_client;

  	struct nlmclnt_initdata nlm_init = {
  		.hostname	= clp->cl_hostname,
  		.address	= (struct sockaddr *)&clp->cl_addr,
  		.addrlen	= clp->cl_addrlen,

  		.nfs_version	= clp->rpc_ops->version,

  		.noresvport	= server->flags & NFS_MOUNT_NORESVPORT ?
  					1 : 0,

  	};

  	if (nlm_init.nfs_version > 3)

  		return 0;

  	if ((server->flags & NFS_MOUNT_LOCAL_FLOCK) &&
  			(server->flags & NFS_MOUNT_LOCAL_FCNTL))

  		return 0;

  	switch (clp->cl_proto) {
  		default:
  			nlm_init.protocol = IPPROTO_TCP;
  			break;
  		case XPRT_TRANSPORT_UDP:
  			nlm_init.protocol = IPPROTO_UDP;
  	}

  	host = nlmclnt_init(&nlm_init);

  	if (IS_ERR(host))
  		return PTR_ERR(host);
  
  	server->nlm_host = host;
  	server->destroy = nfs_destroy_server;
  	return 0;

  }
  
  /*
   * Initialise an NFSv3 ACL client connection
   */
  #ifdef CONFIG_NFS_V3_ACL
  static void nfs_init_server_aclclient(struct nfs_server *server)
  {

  	if (server->nfs_client->rpc_ops->version != 3)

  		goto out_noacl;
  	if (server->flags & NFS_MOUNT_NOACL)
  		goto out_noacl;
  
  	server->client_acl = rpc_bind_new_program(server->client, &nfsacl_program, 3);
  	if (IS_ERR(server->client_acl))
  		goto out_noacl;
  
  	/* No errors! Assume that Sun nfsacls are supported */
  	server->caps |= NFS_CAP_ACLS;
  	return;
  
  out_noacl:
  	server->caps &= ~NFS_CAP_ACLS;
  }
  #else
  static inline void nfs_init_server_aclclient(struct nfs_server *server)
  {
  	server->flags &= ~NFS_MOUNT_NOACL;
  	server->caps &= ~NFS_CAP_ACLS;
  }
  #endif
  
  /*
   * Create a general RPC client
   */

  static int nfs_init_server_rpcclient(struct nfs_server *server,
  		const struct rpc_timeout *timeo,
  		rpc_authflavor_t pseudoflavour)

  {
  	struct nfs_client *clp = server->nfs_client;
  
  	server->client = rpc_clone_client(clp->cl_rpcclient);
  	if (IS_ERR(server->client)) {

  		dprintk("%s: couldn't create rpc_client!
  ", __func__);

  		return PTR_ERR(server->client);
  	}

  	memcpy(&server->client->cl_timeout_default,
  			timeo,
  			sizeof(server->client->cl_timeout_default));
  	server->client->cl_timeout = &server->client->cl_timeout_default;

  	if (pseudoflavour != clp->cl_rpcclient->cl_auth->au_flavor) {
  		struct rpc_auth *auth;
  
  		auth = rpcauth_create(pseudoflavour, server->client);
  		if (IS_ERR(auth)) {

  			dprintk("%s: couldn't create credcache!
  ", __func__);

  			return PTR_ERR(auth);
  		}
  	}
  	server->client->cl_softrtry = 0;
  	if (server->flags & NFS_MOUNT_SOFT)
  		server->client->cl_softrtry = 1;

  	return 0;
  }
  
  /*
   * Initialise an NFS2 or NFS3 client
   */

  int nfs_init_client(struct nfs_client *clp, const struct rpc_timeout *timeparms,
  		    const char *ip_addr, rpc_authflavor_t authflavour,
  		    int noresvport)

  {

  	int error;
  
  	if (clp->cl_cons_state == NFS_CS_READY) {
  		/* the client is already initialised */
  		dprintk("<-- nfs_init_client() = 0 [already %p]
  ", clp);
  		return 0;
  	}

  	/*
  	 * Create a client RPC handle for doing FSSTAT with UNIX auth only
  	 * - RFC 2623, sec 2.3.2
  	 */

  	error = nfs_create_rpc_client(clp, timeparms, RPC_AUTH_UNIX,

  				      0, noresvport);

  	if (error < 0)
  		goto error;
  	nfs_mark_client_ready(clp, NFS_CS_READY);
  	return 0;
  
  error:
  	nfs_mark_client_ready(clp, error);
  	dprintk("<-- nfs_init_client() = xerror %d
  ", error);
  	return error;
  }
  
  /*
   * Create a version 2 or 3 client
   */

  static int nfs_init_server(struct nfs_server *server,
  			   const struct nfs_parsed_mount_data *data)

  {

  	struct nfs_client_initdata cl_init = {
  		.hostname = data->nfs_server.hostname,

  		.addr = (const struct sockaddr *)&data->nfs_server.address,

  		.addrlen = data->nfs_server.addrlen,

  		.rpc_ops = &nfs_v2_clientops,

  		.proto = data->nfs_server.protocol,

  	};

  	struct rpc_timeout timeparms;

  	struct nfs_client *clp;

  	int error;

  
  	dprintk("--> nfs_init_server()
  ");
  
  #ifdef CONFIG_NFS_V3

  	if (data->version == 3)

  		cl_init.rpc_ops = &nfs_v3_clientops;

  #endif

  	nfs_init_timeout_values(&timeparms, data->nfs_server.protocol,
  			data->timeo, data->retrans);

  	/* Allocate or find a client reference we can use */

  	clp = nfs_get_client(&cl_init, &timeparms, NULL, RPC_AUTH_UNIX,
  			     data->flags & NFS_MOUNT_NORESVPORT);

  	if (IS_ERR(clp)) {
  		dprintk("<-- nfs_init_server() = error %ld
  ", PTR_ERR(clp));
  		return PTR_ERR(clp);
  	}

  	server->nfs_client = clp;
  
  	/* Initialise the client representation from the mount data */

  	server->flags = data->flags;

  	server->options = data->options;

  	server->caps |= NFS_CAP_HARDLINKS|NFS_CAP_SYMLINKS|NFS_CAP_FILEID|
  		NFS_CAP_MODE|NFS_CAP_NLINK|NFS_CAP_OWNER|NFS_CAP_OWNER_GROUP|
  		NFS_CAP_ATIME|NFS_CAP_CTIME|NFS_CAP_MTIME;

  
  	if (data->rsize)
  		server->rsize = nfs_block_size(data->rsize, NULL);
  	if (data->wsize)
  		server->wsize = nfs_block_size(data->wsize, NULL);
  
  	server->acregmin = data->acregmin * HZ;
  	server->acregmax = data->acregmax * HZ;
  	server->acdirmin = data->acdirmin * HZ;
  	server->acdirmax = data->acdirmax * HZ;
  
  	/* Start lockd here, before we might error out */
  	error = nfs_start_lockd(server);
  	if (error < 0)
  		goto error;

  	server->port = data->nfs_server.port;

  	error = nfs_init_server_rpcclient(server, &timeparms, data->auth_flavors[0]);

  	if (error < 0)
  		goto error;

  	/* Preserve the values of mount_server-related mount options */
  	if (data->mount_server.addrlen) {
  		memcpy(&server->mountd_address, &data->mount_server.address,
  			data->mount_server.addrlen);
  		server->mountd_addrlen = data->mount_server.addrlen;
  	}
  	server->mountd_version = data->mount_server.version;
  	server->mountd_port = data->mount_server.port;
  	server->mountd_protocol = data->mount_server.protocol;

  	server->namelen  = data->namlen;
  	/* Create a client RPC handle for the NFSv3 ACL management interface */
  	nfs_init_server_aclclient(server);

  	dprintk("<-- nfs_init_server() = 0 [new %p]
  ", clp);
  	return 0;
  
  error:
  	server->nfs_client = NULL;
  	nfs_put_client(clp);
  	dprintk("<-- nfs_init_server() = xerror %d
  ", error);
  	return error;
  }
  
  /*
   * Load up the server record from information gained in an fsinfo record
   */

  static void nfs_server_set_fsinfo(struct nfs_server *server,
  				  struct nfs_fh *mntfh,
  				  struct nfs_fsinfo *fsinfo)

  {
  	unsigned long max_rpc_payload;
  
  	/* Work out a lot of parameters */
  	if (server->rsize == 0)
  		server->rsize = nfs_block_size(fsinfo->rtpref, NULL);
  	if (server->wsize == 0)
  		server->wsize = nfs_block_size(fsinfo->wtpref, NULL);
  
  	if (fsinfo->rtmax >= 512 && server->rsize > fsinfo->rtmax)
  		server->rsize = nfs_block_size(fsinfo->rtmax, NULL);
  	if (fsinfo->wtmax >= 512 && server->wsize > fsinfo->wtmax)
  		server->wsize = nfs_block_size(fsinfo->wtmax, NULL);
  
  	max_rpc_payload = nfs_block_size(rpc_max_payload(server->client), NULL);
  	if (server->rsize > max_rpc_payload)
  		server->rsize = max_rpc_payload;
  	if (server->rsize > NFS_MAX_FILE_IO_SIZE)
  		server->rsize = NFS_MAX_FILE_IO_SIZE;
  	server->rpages = (server->rsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;

  	server->backing_dev_info.name = "nfs";

  	server->backing_dev_info.ra_pages = server->rpages * NFS_MAX_READAHEAD;
  
  	if (server->wsize > max_rpc_payload)
  		server->wsize = max_rpc_payload;
  	if (server->wsize > NFS_MAX_FILE_IO_SIZE)
  		server->wsize = NFS_MAX_FILE_IO_SIZE;
  	server->wpages = (server->wsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;

  	server->pnfs_blksize = fsinfo->blksize;

  	set_pnfs_layoutdriver(server, mntfh, fsinfo->layouttype);

  	server->wtmult = nfs_block_bits(fsinfo->wtmult, NULL);
  
  	server->dtsize = nfs_block_size(fsinfo->dtpref, NULL);

  	if (server->dtsize > PAGE_CACHE_SIZE * NFS_MAX_READDIR_PAGES)
  		server->dtsize = PAGE_CACHE_SIZE * NFS_MAX_READDIR_PAGES;

  	if (server->dtsize > server->rsize)
  		server->dtsize = server->rsize;
  
  	if (server->flags & NFS_MOUNT_NOAC) {
  		server->acregmin = server->acregmax = 0;
  		server->acdirmin = server->acdirmax = 0;
  	}
  
  	server->maxfilesize = fsinfo->maxfilesize;

  	server->time_delta = fsinfo->time_delta;

  	/* We're airborne Set socket buffersize */
  	rpc_setbufsize(server->client, server->wsize + 100, server->rsize + 100);
  }
  
  /*
   * Probe filesystem information, including the FSID on v2/v3
   */
  static int nfs_probe_fsinfo(struct nfs_server *server, struct nfs_fh *mntfh, struct nfs_fattr *fattr)
  {
  	struct nfs_fsinfo fsinfo;
  	struct nfs_client *clp = server->nfs_client;
  	int error;
  
  	dprintk("--> nfs_probe_fsinfo()
  ");
  
  	if (clp->rpc_ops->set_capabilities != NULL) {
  		error = clp->rpc_ops->set_capabilities(server, mntfh);
  		if (error < 0)
  			goto out_error;
  	}
  
  	fsinfo.fattr = fattr;

  	fsinfo.layouttype = 0;

  	error = clp->rpc_ops->fsinfo(server, mntfh, &fsinfo);
  	if (error < 0)
  		goto out_error;

  	nfs_server_set_fsinfo(server, mntfh, &fsinfo);

  
  	/* Get some general file system info */
  	if (server->namelen == 0) {
  		struct nfs_pathconf pathinfo;
  
  		pathinfo.fattr = fattr;
  		nfs_fattr_init(fattr);
  
  		if (clp->rpc_ops->pathconf(server, mntfh, &pathinfo) >= 0)
  			server->namelen = pathinfo.max_namelen;
  	}
  
  	dprintk("<-- nfs_probe_fsinfo() = 0
  ");
  	return 0;
  
  out_error:
  	dprintk("nfs_probe_fsinfo: error = %d
  ", -error);
  	return error;
  }
  
  /*
   * Copy useful information when duplicating a server record
   */
  static void nfs_server_copy_userdata(struct nfs_server *target, struct nfs_server *source)
  {
  	target->flags = source->flags;

  	target->rsize = source->rsize;
  	target->wsize = source->wsize;

  	target->acregmin = source->acregmin;
  	target->acregmax = source->acregmax;
  	target->acdirmin = source->acdirmin;
  	target->acdirmax = source->acdirmax;
  	target->caps = source->caps;

  	target->options = source->options;

  }

  static void nfs_server_insert_lists(struct nfs_server *server)
  {
  	struct nfs_client *clp = server->nfs_client;
  
  	spin_lock(&nfs_client_lock);
  	list_add_tail_rcu(&server->client_link, &clp->cl_superblocks);
  	list_add_tail(&server->master_link, &nfs_volume_list);

  	clear_bit(NFS_CS_STOP_RENEW, &clp->cl_res_state);

  	spin_unlock(&nfs_client_lock);
  
  }
  
  static void nfs_server_remove_lists(struct nfs_server *server)
  {

  	struct nfs_client *clp = server->nfs_client;

  	spin_lock(&nfs_client_lock);
  	list_del_rcu(&server->client_link);

  	if (clp && list_empty(&clp->cl_superblocks))
  		set_bit(NFS_CS_STOP_RENEW, &clp->cl_res_state);

  	list_del(&server->master_link);
  	spin_unlock(&nfs_client_lock);
  
  	synchronize_rcu();
  }

  /*
   * Allocate and initialise a server record
   */
  static struct nfs_server *nfs_alloc_server(void)
  {
  	struct nfs_server *server;
  
  	server = kzalloc(sizeof(struct nfs_server), GFP_KERNEL);
  	if (!server)
  		return NULL;
  
  	server->client = server->client_acl = ERR_PTR(-EINVAL);
  
  	/* Zero out the NFS state stuff */
  	INIT_LIST_HEAD(&server->client_link);
  	INIT_LIST_HEAD(&server->master_link);

  	INIT_LIST_HEAD(&server->delegations);

  	INIT_LIST_HEAD(&server->layouts);

  	INIT_LIST_HEAD(&server->state_owners_lru);

  	atomic_set(&server->active, 0);

  	server->io_stats = nfs_alloc_iostats();
  	if (!server->io_stats) {
  		kfree(server);
  		return NULL;
  	}

  	if (bdi_init(&server->backing_dev_info)) {
  		nfs_free_iostats(server->io_stats);
  		kfree(server);
  		return NULL;
  	}

  	pnfs_init_server(server);

  	return server;
  }
  
  /*
   * Free up a server record
   */
  void nfs_free_server(struct nfs_server *server)
  {
  	dprintk("--> nfs_free_server()
  ");

  	nfs_server_remove_lists(server);

  	unset_pnfs_layoutdriver(server);

  
  	if (server->destroy != NULL)
  		server->destroy(server);

  
  	if (!IS_ERR(server->client_acl))
  		rpc_shutdown_client(server->client_acl);

  	if (!IS_ERR(server->client))
  		rpc_shutdown_client(server->client);
  
  	nfs_put_client(server->nfs_client);
  
  	nfs_free_iostats(server->io_stats);

  	bdi_destroy(&server->backing_dev_info);

  	kfree(server);
  	nfs_release_automount_timer();
  	dprintk("<-- nfs_free_server()
  ");
  }
  
  /*
   * Create a version 2 or 3 volume record
   * - keyed on server and FSID
   */

  struct nfs_server *nfs_create_server(const struct nfs_parsed_mount_data *data,

  				     struct nfs_fh *mntfh)
  {
  	struct nfs_server *server;

  	struct nfs_fattr *fattr;

  	int error;
  
  	server = nfs_alloc_server();
  	if (!server)
  		return ERR_PTR(-ENOMEM);

  	error = -ENOMEM;
  	fattr = nfs_alloc_fattr();
  	if (fattr == NULL)
  		goto error;

  	/* Get a client representation */
  	error = nfs_init_server(server, data);
  	if (error < 0)
  		goto error;
  
  	BUG_ON(!server->nfs_client);
  	BUG_ON(!server->nfs_client->rpc_ops);
  	BUG_ON(!server->nfs_client->rpc_ops->file_inode_ops);
  
  	/* Probe the root fh to retrieve its FSID */

  	error = nfs_probe_fsinfo(server, mntfh, fattr);

  	if (error < 0)
  		goto error;

  	if (server->nfs_client->rpc_ops->version == 3) {
  		if (server->namelen == 0 || server->namelen > NFS3_MAXNAMLEN)
  			server->namelen = NFS3_MAXNAMLEN;
  		if (!(data->flags & NFS_MOUNT_NORDIRPLUS))
  			server->caps |= NFS_CAP_READDIRPLUS;
  	} else {
  		if (server->namelen == 0 || server->namelen > NFS2_MAXNAMLEN)
  			server->namelen = NFS2_MAXNAMLEN;
  	}

  	if (!(fattr->valid & NFS_ATTR_FATTR)) {
  		error = server->nfs_client->rpc_ops->getattr(server, mntfh, fattr);

  		if (error < 0) {
  			dprintk("nfs_create_server: getattr error = %d
  ", -error);
  			goto error;
  		}
  	}

  	memcpy(&server->fsid, &fattr->fsid, sizeof(server->fsid));

  	dprintk("Server FSID: %llx:%llx
  ",
  		(unsigned long long) server->fsid.major,
  		(unsigned long long) server->fsid.minor);

  	nfs_server_insert_lists(server);

  	server->mount_time = jiffies;

  	nfs_free_fattr(fattr);

  	return server;
  
  error:

  	nfs_free_fattr(fattr);

  	nfs_free_server(server);
  	return ERR_PTR(error);
  }
  
  #ifdef CONFIG_NFS_V4
  /*

   * NFSv4.0 callback thread helper
   *
   * Find a client by IP address, protocol version, and minorversion
   *
   * Called from the pg_authenticate method. The callback identifier
   * is not used as it has not been decoded.
   *
   * Returns NULL if no such client
   */
  struct nfs_client *
  nfs4_find_client_no_ident(const struct sockaddr *addr)
  {
  	struct nfs_client *clp;
  
  	spin_lock(&nfs_client_lock);
  	list_for_each_entry(clp, &nfs_client_list, cl_share_link) {
  		if (nfs4_cb_match_client(addr, clp, 0) == false)
  			continue;
  		atomic_inc(&clp->cl_count);
  		spin_unlock(&nfs_client_lock);
  		return clp;
  	}
  	spin_unlock(&nfs_client_lock);
  	return NULL;
  }
  
  /*
   * NFSv4.0 callback thread helper
   *
   * Find a client by callback identifier
   */
  struct nfs_client *
  nfs4_find_client_ident(int cb_ident)
  {
  	struct nfs_client *clp;
  
  	spin_lock(&nfs_client_lock);
  	clp = idr_find(&cb_ident_idr, cb_ident);
  	if (clp)
  		atomic_inc(&clp->cl_count);
  	spin_unlock(&nfs_client_lock);
  	return clp;
  }
  
  #if defined(CONFIG_NFS_V4_1)
  /*
   * NFSv4.1 callback thread helper
   * For CB_COMPOUND calls, find a client by IP address, protocol version,
   * minorversion, and sessionID
   *

   * Returns NULL if no such client
   */
  struct nfs_client *
  nfs4_find_client_sessionid(const struct sockaddr *addr,

  			   struct nfs4_sessionid *sid)

  {
  	struct nfs_client *clp;
  
  	spin_lock(&nfs_client_lock);
  	list_for_each_entry(clp, &nfs_client_list, cl_share_link) {
  		if (nfs4_cb_match_client(addr, clp, 1) == false)
  			continue;
  
  		if (!nfs4_has_session(clp))
  			continue;

  		/* Match sessionid*/
  		if (memcmp(clp->cl_session->sess_id.data,
  		    sid->data, NFS4_MAX_SESSIONID_LEN) != 0)

  			continue;
  
  		atomic_inc(&clp->cl_count);
  		spin_unlock(&nfs_client_lock);
  		return clp;
  	}
  	spin_unlock(&nfs_client_lock);
  	return NULL;
  }
  
  #else /* CONFIG_NFS_V4_1 */
  
  struct nfs_client *
  nfs4_find_client_sessionid(const struct sockaddr *addr,

  			   struct nfs4_sessionid *sid)

  {
  	return NULL;
  }
  #endif /* CONFIG_NFS_V4_1 */
  
  /*

   * Initialize the NFS4 callback service
   */
  static int nfs4_init_callback(struct nfs_client *clp)
  {
  	int error;
  
  	if (clp->rpc_ops->version == 4) {

  		if (nfs4_has_session(clp)) {
  			error = xprt_setup_backchannel(
  						clp->cl_rpcclient->cl_xprt,
  						NFS41_BC_MIN_CALLBACKS);
  			if (error < 0)
  				return error;
  		}

  		error = nfs_callback_up(clp->cl_mvops->minor_version,

  					clp->cl_rpcclient->cl_xprt);

  		if (error < 0) {
  			dprintk("%s: failed to start callback. Error = %d
  ",
  				__func__, error);
  			return error;
  		}
  		__set_bit(NFS_CS_CALLBACK, &clp->cl_res_state);
  	}
  	return 0;
  }
  
  /*

   * Initialize the minor version specific parts of an NFS4 client record
   */
  static int nfs4_init_client_minor_version(struct nfs_client *clp)
  {
  #if defined(CONFIG_NFS_V4_1)

  	if (clp->cl_mvops->minor_version) {

  		struct nfs4_session *session = NULL;
  		/*
  		 * Create the session and mark it expired.
  		 * When a SEQUENCE operation encounters the expired session
  		 * it will do session recovery to initialize it.
  		 */
  		session = nfs4_alloc_session(clp);
  		if (!session)
  			return -ENOMEM;
  
  		clp->cl_session = session;

  		/*
  		 * The create session reply races with the server back
  		 * channel probe. Mark the client NFS_CS_SESSION_INITING
  		 * so that the client back channel can find the
  		 * nfs_client struct
  		 */
  		clp->cl_cons_state = NFS_CS_SESSION_INITING;

  	}
  #endif /* CONFIG_NFS_V4_1 */

  	return nfs4_init_callback(clp);

  }
  
  /*

   * Initialise an NFS4 client record
   */

  int nfs4_init_client(struct nfs_client *clp,
  		     const struct rpc_timeout *timeparms,
  		     const char *ip_addr,
  		     rpc_authflavor_t authflavour,
  		     int noresvport)

  {
  	int error;
  
  	if (clp->cl_cons_state == NFS_CS_READY) {
  		/* the client is initialised already */
  		dprintk("<-- nfs4_init_client() = 0 [already %p]
  ", clp);
  		return 0;
  	}
  
  	/* Check NFS protocol revision and initialize RPC op vector */
  	clp->rpc_ops = &nfs_v4_clientops;

  	error = nfs_create_rpc_client(clp, timeparms, authflavour,

  				      1, noresvport);

  	if (error < 0)
  		goto error;

  	strlcpy(clp->cl_ipaddr, ip_addr, sizeof(clp->cl_ipaddr));

  
  	error = nfs_idmap_new(clp);
  	if (error < 0) {
  		dprintk("%s: failed to create idmapper. Error = %d
  ",

  			__func__, error);

  		goto error;
  	}

  	__set_bit(NFS_CS_IDMAP, &clp->cl_res_state);

  	error = nfs4_init_client_minor_version(clp);
  	if (error < 0)
  		goto error;

  	if (!nfs4_has_session(clp))
  		nfs_mark_client_ready(clp, NFS_CS_READY);

  	return 0;
  
  error:
  	nfs_mark_client_ready(clp, error);
  	dprintk("<-- nfs4_init_client() = xerror %d
  ", error);
  	return error;
  }
  
  /*
   * Set up an NFS4 client
   */
  static int nfs4_set_client(struct nfs_server *server,

  		const char *hostname,
  		const struct sockaddr *addr,
  		const size_t addrlen,

  		const char *ip_addr,

  		rpc_authflavor_t authflavour,

  		int proto, const struct rpc_timeout *timeparms,
  		u32 minorversion)

  {

  	struct nfs_client_initdata cl_init = {
  		.hostname = hostname,

  		.addr = addr,
  		.addrlen = addrlen,

  		.rpc_ops = &nfs_v4_clientops,

  		.proto = proto,

  		.minorversion = minorversion,

  	};

  	struct nfs_client *clp;
  	int error;
  
  	dprintk("--> nfs4_set_client()
  ");
  
  	/* Allocate or find a client reference we can use */

  	clp = nfs_get_client(&cl_init, timeparms, ip_addr, authflavour,
  			     server->flags & NFS_MOUNT_NORESVPORT);

  	if (IS_ERR(clp)) {
  		error = PTR_ERR(clp);
  		goto error;
  	}

  	/*
  	 * Query for the lease time on clientid setup or renewal
  	 *
  	 * Note that this will be set on nfs_clients that were created
  	 * only for the DS role and did not set this bit, but now will
  	 * serve a dual role.
  	 */
  	set_bit(NFS_CS_CHECK_LEASE_TIME, &clp->cl_res_state);

  	server->nfs_client = clp;
  	dprintk("<-- nfs4_set_client() = 0 [new %p]
  ", clp);
  	return 0;

  error:
  	dprintk("<-- nfs4_set_client() = xerror %d
  ", error);
  	return error;
  }

  /*
   * Set up a pNFS Data Server client.
   *
   * Return any existing nfs_client that matches server address,port,version
   * and minorversion.
   *
   * For a new nfs_client, use a soft mount (default), a low retrans and a
   * low timeout interval so that if a connection is lost, we retry through
   * the MDS.
   */
  struct nfs_client *nfs4_set_ds_client(struct nfs_client* mds_clp,
  		const struct sockaddr *ds_addr,
  		int ds_addrlen, int ds_proto)
  {
  	struct nfs_client_initdata cl_init = {
  		.addr = ds_addr,
  		.addrlen = ds_addrlen,
  		.rpc_ops = &nfs_v4_clientops,
  		.proto = ds_proto,
  		.minorversion = mds_clp->cl_minorversion,
  	};
  	struct rpc_timeout ds_timeout = {
  		.to_initval = 15 * HZ,
  		.to_maxval = 15 * HZ,
  		.to_retries = 1,
  		.to_exponential = 1,
  	};
  	struct nfs_client *clp;
  
  	/*
  	 * Set an authflavor equual to the MDS value. Use the MDS nfs_client
  	 * cl_ipaddr so as to use the same EXCHANGE_ID co_ownerid as the MDS
  	 * (section 13.1 RFC 5661).
  	 */
  	clp = nfs_get_client(&cl_init, &ds_timeout, mds_clp->cl_ipaddr,
  			     mds_clp->cl_rpcclient->cl_auth->au_flavor, 0);
  
  	dprintk("<-- %s %p
  ", __func__, clp);
  	return clp;
  }

  EXPORT_SYMBOL_GPL(nfs4_set_ds_client);

  
  /*

   * Session has been established, and the client marked ready.
   * Set the mount rsize and wsize with negotiated fore channel
   * attributes which will be bound checked in nfs_server_set_fsinfo.
   */
  static void nfs4_session_set_rwsize(struct nfs_server *server)
  {
  #ifdef CONFIG_NFS_V4_1

  	struct nfs4_session *sess;
  	u32 server_resp_sz;
  	u32 server_rqst_sz;

  	if (!nfs4_has_session(server->nfs_client))
  		return;

  	sess = server->nfs_client->cl_session;
  	server_resp_sz = sess->fc_attrs.max_resp_sz - nfs41_maxread_overhead;
  	server_rqst_sz = sess->fc_attrs.max_rqst_sz - nfs41_maxwrite_overhead;
  
  	if (server->rsize > server_resp_sz)
  		server->rsize = server_resp_sz;
  	if (server->wsize > server_rqst_sz)
  		server->wsize = server_rqst_sz;

  #endif /* CONFIG_NFS_V4_1 */
  }

  static int nfs4_server_common_setup(struct nfs_server *server,
  		struct nfs_fh *mntfh)
  {
  	struct nfs_fattr *fattr;
  	int error;
  
  	BUG_ON(!server->nfs_client);
  	BUG_ON(!server->nfs_client->rpc_ops);
  	BUG_ON(!server->nfs_client->rpc_ops->file_inode_ops);

  	/* data servers support only a subset of NFSv4.1 */
  	if (is_ds_only_client(server->nfs_client))
  		return -EPROTONOSUPPORT;

  	fattr = nfs_alloc_fattr();
  	if (fattr == NULL)
  		return -ENOMEM;
  
  	/* We must ensure the session is initialised first */
  	error = nfs4_init_session(server);
  	if (error < 0)
  		goto out;
  
  	/* Probe the root fh to retrieve its FSID and filehandle */
  	error = nfs4_get_rootfh(server, mntfh);
  	if (error < 0)
  		goto out;
  
  	dprintk("Server FSID: %llx:%llx
  ",
  			(unsigned long long) server->fsid.major,
  			(unsigned long long) server->fsid.minor);
  	dprintk("Mount FH: %d
  ", mntfh->size);
  
  	nfs4_session_set_rwsize(server);
  
  	error = nfs_probe_fsinfo(server, mntfh, fattr);
  	if (error < 0)
  		goto out;
  
  	if (server->namelen == 0 || server->namelen > NFS4_MAXNAMLEN)
  		server->namelen = NFS4_MAXNAMLEN;

  	nfs_server_insert_lists(server);

  	server->mount_time = jiffies;

  	server->destroy = nfs4_destroy_server;

  out:
  	nfs_free_fattr(fattr);
  	return error;
  }

  /*

   * Create a version 4 volume record
   */
  static int nfs4_init_server(struct nfs_server *server,

  		const struct nfs_parsed_mount_data *data)

  {

  	struct rpc_timeout timeparms;

  	int error;
  
  	dprintk("--> nfs4_init_server()
  ");

  	nfs_init_timeout_values(&timeparms, data->nfs_server.protocol,
  			data->timeo, data->retrans);

  	/* Initialise the client representation from the mount data */
  	server->flags = data->flags;

  	server->caps |= NFS_CAP_ATOMIC_OPEN|NFS_CAP_CHANGE_ATTR|NFS_CAP_POSIX_LOCK;
  	if (!(data->flags & NFS_MOUNT_NORDIRPLUS))
  			server->caps |= NFS_CAP_READDIRPLUS;

  	server->options = data->options;

  	/* Get a client record */
  	error = nfs4_set_client(server,
  			data->nfs_server.hostname,
  			(const struct sockaddr *)&data->nfs_server.address,
  			data->nfs_server.addrlen,
  			data->client_address,
  			data->auth_flavors[0],
  			data->nfs_server.protocol,

  			&timeparms,
  			data->minorversion);

  	if (error < 0)
  		goto error;

  	/*
  	 * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
  	 * authentication.
  	 */
  	if (nfs4_disable_idmapping && data->auth_flavors[0] == RPC_AUTH_UNIX)
  		server->caps |= NFS_CAP_UIDGID_NOMAP;

  	if (data->rsize)
  		server->rsize = nfs_block_size(data->rsize, NULL);
  	if (data->wsize)
  		server->wsize = nfs_block_size(data->wsize, NULL);
  
  	server->acregmin = data->acregmin * HZ;
  	server->acregmax = data->acregmax * HZ;
  	server->acdirmin = data->acdirmin * HZ;
  	server->acdirmax = data->acdirmax * HZ;

  	server->port = data->nfs_server.port;

  	error = nfs_init_server_rpcclient(server, &timeparms, data->auth_flavors[0]);

  error:

  	/* Done */
  	dprintk("<-- nfs4_init_server() = %d
  ", error);
  	return error;
  }
  
  /*
   * Create a version 4 volume record
   * - keyed on server and FSID
   */

  struct nfs_server *nfs4_create_server(const struct nfs_parsed_mount_data *data,

  				      struct nfs_fh *mntfh)
  {

  	struct nfs_server *server;
  	int error;
  
  	dprintk("--> nfs4_create_server()
  ");
  
  	server = nfs_alloc_server();
  	if (!server)
  		return ERR_PTR(-ENOMEM);

  	/* set up the general RPC client */

  	error = nfs4_init_server(server, data);

  	if (error < 0)
  		goto error;

  	error = nfs4_server_common_setup(server, mntfh);

  	if (error < 0)
  		goto error;

  	dprintk("<-- nfs4_create_server() = %p
  ", server);
  	return server;
  
  error:
  	nfs_free_server(server);
  	dprintk("<-- nfs4_create_server() = error %d
  ", error);
  	return ERR_PTR(error);
  }
  
  /*
   * Create an NFS4 referral server record
   */
  struct nfs_server *nfs4_create_referral_server(struct nfs_clone_mount *data,

  					       struct nfs_fh *mntfh)

  {
  	struct nfs_client *parent_client;
  	struct nfs_server *server, *parent_server;

  	int error;
  
  	dprintk("--> nfs4_create_referral_server()
  ");
  
  	server = nfs_alloc_server();
  	if (!server)
  		return ERR_PTR(-ENOMEM);
  
  	parent_server = NFS_SB(data->sb);
  	parent_client = parent_server->nfs_client;

  	/* Initialise the client representation from the parent server */
  	nfs_server_copy_userdata(server, parent_server);

  	server->caps |= NFS_CAP_ATOMIC_OPEN|NFS_CAP_CHANGE_ATTR;

  	/* Get a client representation.
  	 * Note: NFSv4 always uses TCP, */

  	error = nfs4_set_client(server, data->hostname,

  				data->addr,
  				data->addrlen,

  				parent_client->cl_ipaddr,
  				data->authflavor,
  				parent_server->client->cl_xprt->prot,

  				parent_server->client->cl_timeout,

  				parent_client->cl_mvops->minor_version);

  	if (error < 0)
  		goto error;

  	error = nfs_init_server_rpcclient(server, parent_server->client->cl_timeout, data->authflavor);

  	if (error < 0)
  		goto error;

  	error = nfs4_server_common_setup(server, mntfh);

  	if (error < 0)
  		goto error;

  	dprintk("<-- nfs_create_referral_server() = %p
  ", server);
  	return server;
  
  error:
  	nfs_free_server(server);
  	dprintk("<-- nfs4_create_referral_server() = error %d
  ", error);
  	return ERR_PTR(error);
  }
  
  #endif /* CONFIG_NFS_V4 */
  
  /*
   * Clone an NFS2, NFS3 or NFS4 server record
   */
  struct nfs_server *nfs_clone_server(struct nfs_server *source,
  				    struct nfs_fh *fh,
  				    struct nfs_fattr *fattr)
  {
  	struct nfs_server *server;

  	struct nfs_fattr *fattr_fsinfo;

  	int error;
  
  	dprintk("--> nfs_clone_server(,%llx:%llx,)
  ",

  		(unsigned long long) fattr->fsid.major,
  		(unsigned long long) fattr->fsid.minor);

  
  	server = nfs_alloc_server();
  	if (!server)
  		return ERR_PTR(-ENOMEM);

  	error = -ENOMEM;
  	fattr_fsinfo = nfs_alloc_fattr();
  	if (fattr_fsinfo == NULL)
  		goto out_free_server;

  	/* Copy data from the source */
  	server->nfs_client = source->nfs_client;

  	server->destroy = source->destroy;

  	atomic_inc(&server->nfs_client->cl_count);
  	nfs_server_copy_userdata(server, source);
  
  	server->fsid = fattr->fsid;

  	error = nfs_init_server_rpcclient(server,
  			source->client->cl_timeout,
  			source->client->cl_auth->au_flavor);

  	if (error < 0)
  		goto out_free_server;
  	if (!IS_ERR(source->client_acl))
  		nfs_init_server_aclclient(server);
  
  	/* probe the filesystem info for this server filesystem */

  	error = nfs_probe_fsinfo(server, fh, fattr_fsinfo);

  	if (error < 0)
  		goto out_free_server;

  	if (server->namelen == 0 || server->namelen > NFS4_MAXNAMLEN)
  		server->namelen = NFS4_MAXNAMLEN;

  	dprintk("Cloned FSID: %llx:%llx
  ",

  		(unsigned long long) server->fsid.major,
  		(unsigned long long) server->fsid.minor);

  
  	error = nfs_start_lockd(server);
  	if (error < 0)
  		goto out_free_server;

  	nfs_server_insert_lists(server);

  	server->mount_time = jiffies;

  	nfs_free_fattr(fattr_fsinfo);

  	dprintk("<-- nfs_clone_server() = %p
  ", server);
  	return server;
  
  out_free_server:

  	nfs_free_fattr(fattr_fsinfo);

  	nfs_free_server(server);
  	dprintk("<-- nfs_clone_server() = error %d
  ", error);
  	return ERR_PTR(error);
  }

  
  #ifdef CONFIG_PROC_FS
  static struct proc_dir_entry *proc_fs_nfs;
  
  static int nfs_server_list_open(struct inode *inode, struct file *file);
  static void *nfs_server_list_start(struct seq_file *p, loff_t *pos);
  static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos);
  static void nfs_server_list_stop(struct seq_file *p, void *v);
  static int nfs_server_list_show(struct seq_file *m, void *v);

  static const struct seq_operations nfs_server_list_ops = {

  	.start	= nfs_server_list_start,
  	.next	= nfs_server_list_next,
  	.stop	= nfs_server_list_stop,
  	.show	= nfs_server_list_show,
  };

  static const struct file_operations nfs_server_list_fops = {

  	.open		= nfs_server_list_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= seq_release,

  	.owner		= THIS_MODULE,

  };
  
  static int nfs_volume_list_open(struct inode *inode, struct file *file);
  static void *nfs_volume_list_start(struct seq_file *p, loff_t *pos);
  static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos);
  static void nfs_volume_list_stop(struct seq_file *p, void *v);
  static int nfs_volume_list_show(struct seq_file *m, void *v);

  static const struct seq_operations nfs_volume_list_ops = {

  	.start	= nfs_volume_list_start,
  	.next	= nfs_volume_list_next,
  	.stop	= nfs_volume_list_stop,
  	.show	= nfs_volume_list_show,
  };

  static const struct file_operations nfs_volume_list_fops = {

  	.open		= nfs_volume_list_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= seq_release,

  	.owner		= THIS_MODULE,

  };
  
  /*
   * open "/proc/fs/nfsfs/servers" which provides a summary of servers with which
   * we're dealing
   */
  static int nfs_server_list_open(struct inode *inode, struct file *file)
  {
  	struct seq_file *m;
  	int ret;
  
  	ret = seq_open(file, &nfs_server_list_ops);
  	if (ret < 0)
  		return ret;
  
  	m = file->private_data;
  	m->private = PDE(inode)->data;
  
  	return 0;
  }
  
  /*
   * set up the iterator to start reading from the server list and return the first item
   */
  static void *nfs_server_list_start(struct seq_file *m, loff_t *_pos)
  {

  	/* lock the list against modification */
  	spin_lock(&nfs_client_lock);

  	return seq_list_start_head(&nfs_client_list, *_pos);

  }
  
  /*
   * move to next server
   */
  static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos)
  {

  	return seq_list_next(v, &nfs_client_list, pos);

  }
  
  /*
   * clean up after reading from the transports list
   */
  static void nfs_server_list_stop(struct seq_file *p, void *v)
  {
  	spin_unlock(&nfs_client_lock);
  }
  
  /*
   * display a header line followed by a load of call lines
   */
  static int nfs_server_list_show(struct seq_file *m, void *v)
  {
  	struct nfs_client *clp;
  
  	/* display header on line 1 */

  	if (v == &nfs_client_list) {

  		seq_puts(m, "NV SERVER   PORT USE HOSTNAME
  ");
  		return 0;
  	}
  
  	/* display one transport per line on subsequent lines */
  	clp = list_entry(v, struct nfs_client, cl_share_link);

  	/* Check if the client is initialized */
  	if (clp->cl_cons_state != NFS_CS_READY)
  		return 0;

  	seq_printf(m, "v%u %s %s %3d %s
  ",

  		   clp->rpc_ops->version,

  		   rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_ADDR),
  		   rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_PORT),

  		   atomic_read(&clp->cl_count),
  		   clp->cl_hostname);
  
  	return 0;
  }
  
  /*
   * open "/proc/fs/nfsfs/volumes" which provides a summary of extant volumes
   */
  static int nfs_volume_list_open(struct inode *inode, struct file *file)
  {
  	struct seq_file *m;
  	int ret;
  
  	ret = seq_open(file, &nfs_volume_list_ops);
  	if (ret < 0)
  		return ret;
  
  	m = file->private_data;
  	m->private = PDE(inode)->data;
  
  	return 0;
  }
  
  /*
   * set up the iterator to start reading from the volume list and return the first item
   */
  static void *nfs_volume_list_start(struct seq_file *m, loff_t *_pos)
  {

  	/* lock the list against modification */
  	spin_lock(&nfs_client_lock);

  	return seq_list_start_head(&nfs_volume_list, *_pos);

  }
  
  /*
   * move to next volume
   */
  static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos)
  {

  	return seq_list_next(v, &nfs_volume_list, pos);

  }
  
  /*
   * clean up after reading from the transports list
   */
  static void nfs_volume_list_stop(struct seq_file *p, void *v)
  {
  	spin_unlock(&nfs_client_lock);
  }
  
  /*
   * display a header line followed by a load of call lines
   */
  static int nfs_volume_list_show(struct seq_file *m, void *v)
  {
  	struct nfs_server *server;
  	struct nfs_client *clp;
  	char dev[8], fsid[17];
  
  	/* display header on line 1 */

  	if (v == &nfs_volume_list) {

  		seq_puts(m, "NV SERVER   PORT DEV     FSID              FSC
  ");

  		return 0;
  	}
  	/* display one transport per line on subsequent lines */
  	server = list_entry(v, struct nfs_server, master_link);
  	clp = server->nfs_client;
  
  	snprintf(dev, 8, "%u:%u",
  		 MAJOR(server->s_dev), MINOR(server->s_dev));
  
  	snprintf(fsid, 17, "%llx:%llx",

  		 (unsigned long long) server->fsid.major,
  		 (unsigned long long) server->fsid.minor);

  	seq_printf(m, "v%u %s %s %-7s %-17s %s
  ",

  		   clp->rpc_ops->version,

  		   rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_ADDR),
  		   rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_HEX_PORT),

  		   dev,

  		   fsid,
  		   nfs_server_fscache_state(server));

  
  	return 0;
  }
  
  /*
   * initialise the /proc/fs/nfsfs/ directory
   */
  int __init nfs_fs_proc_init(void)
  {
  	struct proc_dir_entry *p;

  	proc_fs_nfs = proc_mkdir("fs/nfsfs", NULL);

  	if (!proc_fs_nfs)
  		goto error_0;

  	/* a file of servers with which we're dealing */

  	p = proc_create("servers", S_IFREG|S_IRUGO,
  			proc_fs_nfs, &nfs_server_list_fops);

  	if (!p)
  		goto error_1;

  	/* a file of volumes that we have mounted */

  	p = proc_create("volumes", S_IFREG|S_IRUGO,
  			proc_fs_nfs, &nfs_volume_list_fops);

  	if (!p)
  		goto error_2;

  	return 0;
  
  error_2:
  	remove_proc_entry("servers", proc_fs_nfs);
  error_1:

  	remove_proc_entry("fs/nfsfs", NULL);

  error_0:
  	return -ENOMEM;
  }
  
  /*
   * clean up the /proc/fs/nfsfs/ directory
   */
  void nfs_fs_proc_exit(void)
  {
  	remove_proc_entry("volumes", proc_fs_nfs);
  	remove_proc_entry("servers", proc_fs_nfs);

  	remove_proc_entry("fs/nfsfs", NULL);

  }
  
  #endif /* CONFIG_PROC_FS */

  
  module_param(nfs4_disable_idmapping, bool, 0644);
  MODULE_PARM_DESC(nfs4_disable_idmapping,
  		"Turn off NFSv4 idmapping when using 'sec=sys'");