/*
   *  fs/nfs/nfs4state.c
   *
   *  Client-side XDR for NFSv4.
   *
   *  Copyright (c) 2002 The Regents of the University of Michigan.
   *  All rights reserved.
   *
   *  Kendrick Smith <kmsmith@umich.edu>
   *
   *  Redistribution and use in source and binary forms, with or without
   *  modification, are permitted provided that the following conditions
   *  are met:
   *
   *  1. Redistributions of source code must retain the above copyright
   *     notice, this list of conditions and the following disclaimer.
   *  2. Redistributions in binary form must reproduce the above copyright
   *     notice, this list of conditions and the following disclaimer in the
   *     documentation and/or other materials provided with the distribution.
   *  3. Neither the name of the University nor the names of its
   *     contributors may be used to endorse or promote products derived
   *     from this software without specific prior written permission.
   *
   *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
   *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
   *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * Implementation of the NFSv4 state model.  For the time being,
   * this is minimal, but will be made much more complex in a
   * subsequent patch.
   */

  #include <linux/kernel.h>

  #include <linux/slab.h>

  #include <linux/fs.h>

  #include <linux/nfs_fs.h>

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

  #include <linux/random.h>

  #include <linux/ratelimit.h>

  #include <linux/workqueue.h>
  #include <linux/bitops.h>

  #include <linux/jiffies.h>

  #include <linux/sunrpc/clnt.h>

  #include "nfs4_fs.h"

  #include "callback.h"
  #include "delegation.h"

  #include "internal.h"

  #include "nfs4idmap.h"

  #include "nfs4session.h"

  #include "pnfs.h"

  #include "netns.h"

  #include "nfs4trace.h"

  #define NFSDBG_FACILITY		NFSDBG_STATE

  #define OPENOWNER_POOL_SIZE	8

  const nfs4_stateid zero_stateid = {

  	{ .data = { 0 } },

  	.type = NFS4_SPECIAL_STATEID_TYPE,
  };

  const nfs4_stateid invalid_stateid = {
  	{

  		/* Funky initialiser keeps older gcc versions happy */
  		.data = { 0xff, 0xff, 0xff, 0xff, 0 },

  	},
  	.type = NFS4_INVALID_STATEID_TYPE,
  };

  const nfs4_stateid current_stateid = {
  	{
  		/* Funky initialiser keeps older gcc versions happy */
  		.data = { 0x0, 0x0, 0x0, 0x1, 0 },
  	},
  	.type = NFS4_SPECIAL_STATEID_TYPE,
  };

  static DEFINE_MUTEX(nfs_clid_init_mutex);

  static int nfs4_setup_state_renewal(struct nfs_client *clp)
  {
  	int status;
  	struct nfs_fsinfo fsinfo;

  
  	if (!test_bit(NFS_CS_CHECK_LEASE_TIME, &clp->cl_res_state)) {
  		nfs4_schedule_state_renewal(clp);
  		return 0;
  	}

  	status = nfs4_proc_get_lease_time(clp, &fsinfo);
  	if (status == 0) {

  		nfs4_set_lease_period(clp, fsinfo.lease_time * HZ);

  		nfs4_schedule_state_renewal(clp);
  	}
  
  	return status;
  }

  int nfs4_init_clientid(struct nfs_client *clp, const struct cred *cred)

  {

  	struct nfs4_setclientid_res clid = {
  		.clientid = clp->cl_clientid,
  		.confirm = clp->cl_confirm,
  	};

  	unsigned short port;
  	int status;

  	struct nfs_net *nn = net_generic(clp->cl_net, nfs_net_id);

  	if (test_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state))
  		goto do_confirm;

  	port = nn->nfs_callback_tcpport;

  	if (clp->cl_addr.ss_family == AF_INET6)

  		port = nn->nfs_callback_tcpport6;

  	status = nfs4_proc_setclientid(clp, NFS4_CALLBACK, port, cred, &clid);
  	if (status != 0)
  		goto out;

  	clp->cl_clientid = clid.clientid;
  	clp->cl_confirm = clid.confirm;
  	set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
  do_confirm:

  	status = nfs4_proc_setclientid_confirm(clp, &clid, cred);
  	if (status != 0)
  		goto out;

  	clear_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);

  	nfs4_setup_state_renewal(clp);

  out:

  	return status;
  }

  /**
   * nfs40_discover_server_trunking - Detect server IP address trunking (mv0)
   *
   * @clp: nfs_client under test
   * @result: OUT: found nfs_client, or clp
   * @cred: credential to use for trunking test
   *
   * Returns zero, a negative errno, or a negative NFS4ERR status.
   * If zero is returned, an nfs_client pointer is planted in
   * "result".
   *
   * Note: The returned client may not yet be marked ready.
   */
  int nfs40_discover_server_trunking(struct nfs_client *clp,
  				   struct nfs_client **result,

  				   const struct cred *cred)

  {
  	struct nfs4_setclientid_res clid = {
  		.clientid = clp->cl_clientid,
  		.confirm = clp->cl_confirm,
  	};

  	struct nfs_net *nn = net_generic(clp->cl_net, nfs_net_id);

  	unsigned short port;
  	int status;

  	port = nn->nfs_callback_tcpport;

  	if (clp->cl_addr.ss_family == AF_INET6)

  		port = nn->nfs_callback_tcpport6;

  
  	status = nfs4_proc_setclientid(clp, NFS4_CALLBACK, port, cred, &clid);
  	if (status != 0)
  		goto out;
  	clp->cl_clientid = clid.clientid;
  	clp->cl_confirm = clid.confirm;
  
  	status = nfs40_walk_client_list(clp, result, cred);

  	if (status == 0) {

  		/* Sustain the lease, even if it's empty.  If the clientid4
  		 * goes stale it's of no use for trunking discovery. */
  		nfs4_schedule_state_renewal(*result);

  
  		/* If the client state need to recover, do it. */
  		if (clp->cl_state)
  			nfs4_schedule_state_manager(clp);

  	}

  out:
  	return status;
  }

  const struct cred *nfs4_get_machine_cred(struct nfs_client *clp)

  {

  	return get_cred(rpc_machine_cred());

  }

  static void nfs4_root_machine_cred(struct nfs_client *clp)
  {

  	/* Force root creds instead of machine */
  	clp->cl_principal = NULL;
  	clp->cl_rpcclient->cl_principal = NULL;

  }

  static const struct cred *

  nfs4_get_renew_cred_server_locked(struct nfs_server *server)

  {

  	const struct cred *cred = NULL;

  	struct nfs4_state_owner *sp;

  	struct rb_node *pos;

  	for (pos = rb_first(&server->state_owners);
  	     pos != NULL;
  	     pos = rb_next(pos)) {
  		sp = rb_entry(pos, struct nfs4_state_owner, so_server_node);

  		if (list_empty(&sp->so_states))
  			continue;

  		cred = get_cred(sp->so_cred);

  		break;
  	}
  	return cred;
  }

  /**

   * nfs4_get_renew_cred - Acquire credential for a renew operation

   * @clp: client state handle
   *
   * Returns an rpc_cred with reference count bumped, or NULL.
   * Caller must hold clp->cl_lock.
   */

  const struct cred *nfs4_get_renew_cred(struct nfs_client *clp)

  {

  	const struct cred *cred = NULL;

  	struct nfs_server *server;

  	/* Use machine credentials if available */

  	cred = nfs4_get_machine_cred(clp);

  	if (cred != NULL)
  		goto out;

  	spin_lock(&clp->cl_lock);

  	rcu_read_lock();
  	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
  		cred = nfs4_get_renew_cred_server_locked(server);
  		if (cred != NULL)
  			break;
  	}
  	rcu_read_unlock();

  	spin_unlock(&clp->cl_lock);

  
  out:

  	return cred;
  }

  static void nfs4_end_drain_slot_table(struct nfs4_slot_table *tbl)

  {

  	if (test_and_clear_bit(NFS4_SLOT_TBL_DRAINING, &tbl->slot_tbl_state)) {

  		spin_lock(&tbl->slot_tbl_lock);

  		nfs41_wake_slot_table(tbl);

  		spin_unlock(&tbl->slot_tbl_lock);

  	}

  }

  static void nfs4_end_drain_session(struct nfs_client *clp)
  {
  	struct nfs4_session *ses = clp->cl_session;

  	if (clp->cl_slot_tbl) {
  		nfs4_end_drain_slot_table(clp->cl_slot_tbl);
  		return;
  	}

  	if (ses != NULL) {
  		nfs4_end_drain_slot_table(&ses->bc_slot_table);
  		nfs4_end_drain_slot_table(&ses->fc_slot_table);
  	}
  }

  static int nfs4_drain_slot_tbl(struct nfs4_slot_table *tbl)

  {

  	set_bit(NFS4_SLOT_TBL_DRAINING, &tbl->slot_tbl_state);

  	spin_lock(&tbl->slot_tbl_lock);

  	if (tbl->highest_used_slotid != NFS4_NO_SLOT) {

  		reinit_completion(&tbl->complete);

  		spin_unlock(&tbl->slot_tbl_lock);

  		return wait_for_completion_interruptible(&tbl->complete);

  	}
  	spin_unlock(&tbl->slot_tbl_lock);
  	return 0;
  }

  static int nfs4_begin_drain_session(struct nfs_client *clp)
  {
  	struct nfs4_session *ses = clp->cl_session;

  	int ret;

  	if (clp->cl_slot_tbl)
  		return nfs4_drain_slot_tbl(clp->cl_slot_tbl);

  	/* back channel */

  	ret = nfs4_drain_slot_tbl(&ses->bc_slot_table);

  	if (ret)
  		return ret;
  	/* fore channel */

  	return nfs4_drain_slot_tbl(&ses->fc_slot_table);

  }

  #if defined(CONFIG_NFS_V4_1)

  static void nfs41_finish_session_reset(struct nfs_client *clp)
  {
  	clear_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
  	clear_bit(NFS4CLNT_SESSION_RESET, &clp->cl_state);
  	/* create_session negotiated new slot table */

  	clear_bit(NFS4CLNT_BIND_CONN_TO_SESSION, &clp->cl_state);

  	nfs4_setup_state_renewal(clp);

  }

  int nfs41_init_clientid(struct nfs_client *clp, const struct cred *cred)

  {
  	int status;

  	if (test_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state))
  		goto do_confirm;

  	status = nfs4_proc_exchange_id(clp, cred);

  	if (status != 0)
  		goto out;

  	set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
  do_confirm:

  	status = nfs4_proc_create_session(clp, cred);

  	if (status != 0)
  		goto out;

  	nfs41_finish_session_reset(clp);

  	nfs_mark_client_ready(clp, NFS_CS_READY);
  out:

  	return status;
  }

  /**
   * nfs41_discover_server_trunking - Detect server IP address trunking (mv1)
   *
   * @clp: nfs_client under test
   * @result: OUT: found nfs_client, or clp
   * @cred: credential to use for trunking test
   *
   * Returns NFS4_OK, a negative errno, or a negative NFS4ERR status.
   * If NFS4_OK is returned, an nfs_client pointer is planted in
   * "result".
   *
   * Note: The returned client may not yet be marked ready.
   */
  int nfs41_discover_server_trunking(struct nfs_client *clp,
  				   struct nfs_client **result,

  				   const struct cred *cred)

  {
  	int status;
  
  	status = nfs4_proc_exchange_id(clp, cred);
  	if (status != NFS4_OK)
  		return status;

  	status = nfs41_walk_client_list(clp, result, cred);
  	if (status < 0)
  		return status;
  	if (clp != *result)
  		return 0;

  	/*
  	 * Purge state if the client id was established in a prior
  	 * instance and the client id could not have arrived on the
  	 * server via Transparent State Migration.
  	 */
  	if (clp->cl_exchange_flags & EXCHGID4_FLAG_CONFIRMED_R) {
  		if (!test_bit(NFS_CS_TSM_POSSIBLE, &clp->cl_flags))
  			set_bit(NFS4CLNT_PURGE_STATE, &clp->cl_state);
  		else
  			set_bit(NFS4CLNT_LEASE_CONFIRM, &clp->cl_state);
  	}

  	nfs4_schedule_state_manager(clp);
  	status = nfs_wait_client_init_complete(clp);
  	if (status < 0)
  		nfs_put_client(clp);
  	return status;

  }

  #endif /* CONFIG_NFS_V4_1 */

  /**

   * nfs4_get_clid_cred - Acquire credential for a setclientid operation

   * @clp: client state handle
   *

   * Returns a cred with reference count bumped, or NULL.

   */

  const struct cred *nfs4_get_clid_cred(struct nfs_client *clp)

  {

  	const struct cred *cred;

  	cred = nfs4_get_machine_cred(clp);

  	return cred;

  }

  static struct nfs4_state_owner *

  nfs4_find_state_owner_locked(struct nfs_server *server, const struct cred *cred)

  {

  	struct rb_node **p = &server->state_owners.rb_node,

  		       *parent = NULL;

  	struct nfs4_state_owner *sp;

  	int cmp;

  	while (*p != NULL) {
  		parent = *p;

  		sp = rb_entry(parent, struct nfs4_state_owner, so_server_node);

  		cmp = cred_fscmp(cred, sp->so_cred);

  		if (cmp < 0)

  			p = &parent->rb_left;

  		else if (cmp > 0)

  			p = &parent->rb_right;
  		else {

  			if (!list_empty(&sp->so_lru))
  				list_del_init(&sp->so_lru);

  			atomic_inc(&sp->so_count);

  			return sp;

  		}

  	}

  	return NULL;

  }

  static struct nfs4_state_owner *

  nfs4_insert_state_owner_locked(struct nfs4_state_owner *new)

  {

  	struct nfs_server *server = new->so_server;
  	struct rb_node **p = &server->state_owners.rb_node,

  		       *parent = NULL;
  	struct nfs4_state_owner *sp;

  	int cmp;

  
  	while (*p != NULL) {
  		parent = *p;

  		sp = rb_entry(parent, struct nfs4_state_owner, so_server_node);

  		cmp = cred_fscmp(new->so_cred, sp->so_cred);

  		if (cmp < 0)

  			p = &parent->rb_left;

  		else if (cmp > 0)

  			p = &parent->rb_right;
  		else {

  			if (!list_empty(&sp->so_lru))
  				list_del_init(&sp->so_lru);

  			atomic_inc(&sp->so_count);
  			return sp;
  		}
  	}

  	rb_link_node(&new->so_server_node, parent, p);
  	rb_insert_color(&new->so_server_node, &server->state_owners);

  	return new;
  }
  
  static void

  nfs4_remove_state_owner_locked(struct nfs4_state_owner *sp)

  {

  	struct nfs_server *server = sp->so_server;
  
  	if (!RB_EMPTY_NODE(&sp->so_server_node))
  		rb_erase(&sp->so_server_node, &server->state_owners);

  }

  static void
  nfs4_init_seqid_counter(struct nfs_seqid_counter *sc)
  {

  	sc->create_time = ktime_get();

  	sc->flags = 0;
  	sc->counter = 0;
  	spin_lock_init(&sc->lock);
  	INIT_LIST_HEAD(&sc->list);
  	rpc_init_wait_queue(&sc->wait, "Seqid_waitqueue");
  }
  
  static void
  nfs4_destroy_seqid_counter(struct nfs_seqid_counter *sc)
  {
  	rpc_destroy_wait_queue(&sc->wait);
  }

  /*
   * nfs4_alloc_state_owner(): this is called on the OPEN or CREATE path to
   * create a new state_owner.
   *
   */
  static struct nfs4_state_owner *

  nfs4_alloc_state_owner(struct nfs_server *server,

  		const struct cred *cred,

  		gfp_t gfp_flags)

  {
  	struct nfs4_state_owner *sp;

  	sp = kzalloc(sizeof(*sp), gfp_flags);

  	if (!sp)
  		return NULL;

  	sp->so_seqid.owner_id = ida_simple_get(&server->openowner_id, 0, 0,
  						gfp_flags);
  	if (sp->so_seqid.owner_id < 0) {
  		kfree(sp);
  		return NULL;
  	}

  	sp->so_server = server;

  	sp->so_cred = get_cred(cred);

  	spin_lock_init(&sp->so_lock);

  	INIT_LIST_HEAD(&sp->so_states);

  	nfs4_init_seqid_counter(&sp->so_seqid);

  	atomic_set(&sp->so_count, 1);

  	INIT_LIST_HEAD(&sp->so_lru);

  	seqcount_spinlock_init(&sp->so_reclaim_seqcount, &sp->so_lock);

  	mutex_init(&sp->so_delegreturn_mutex);

  	return sp;
  }

  static void

  nfs4_reset_state_owner(struct nfs4_state_owner *sp)

  {

  	/* This state_owner is no longer usable, but must
  	 * remain in place so that state recovery can find it
  	 * and the opens associated with it.
  	 * It may also be used for new 'open' request to
  	 * return a delegation to the server.
  	 * So update the 'create_time' so that it looks like
  	 * a new state_owner.  This will cause the server to
  	 * request an OPEN_CONFIRM to start a new sequence.
  	 */
  	sp->so_seqid.create_time = ktime_get();

  }

  static void nfs4_free_state_owner(struct nfs4_state_owner *sp)
  {

  	nfs4_destroy_seqid_counter(&sp->so_seqid);

  	put_cred(sp->so_cred);

  	ida_simple_remove(&sp->so_server->openowner_id, sp->so_seqid.owner_id);

  	kfree(sp);
  }
  
  static void nfs4_gc_state_owners(struct nfs_server *server)
  {
  	struct nfs_client *clp = server->nfs_client;
  	struct nfs4_state_owner *sp, *tmp;
  	unsigned long time_min, time_max;
  	LIST_HEAD(doomed);
  
  	spin_lock(&clp->cl_lock);
  	time_max = jiffies;
  	time_min = (long)time_max - (long)clp->cl_lease_time;
  	list_for_each_entry_safe(sp, tmp, &server->state_owners_lru, so_lru) {
  		/* NB: LRU is sorted so that oldest is at the head */
  		if (time_in_range(sp->so_expires, time_min, time_max))
  			break;
  		list_move(&sp->so_lru, &doomed);
  		nfs4_remove_state_owner_locked(sp);
  	}
  	spin_unlock(&clp->cl_lock);
  
  	list_for_each_entry_safe(sp, tmp, &doomed, so_lru) {
  		list_del(&sp->so_lru);
  		nfs4_free_state_owner(sp);
  	}
  }

  /**
   * nfs4_get_state_owner - Look up a state owner given a credential
   * @server: nfs_server to search
   * @cred: RPC credential to match

   * @gfp_flags: allocation mode

   *
   * Returns a pointer to an instantiated nfs4_state_owner struct, or NULL.
   */
  struct nfs4_state_owner *nfs4_get_state_owner(struct nfs_server *server,

  					      const struct cred *cred,

  					      gfp_t gfp_flags)

  {

  	struct nfs_client *clp = server->nfs_client;

  	struct nfs4_state_owner *sp, *new;

  	spin_lock(&clp->cl_lock);

  	sp = nfs4_find_state_owner_locked(server, cred);

  	spin_unlock(&clp->cl_lock);

  	if (sp != NULL)

  		goto out;

  	new = nfs4_alloc_state_owner(server, cred, gfp_flags);

  	if (new == NULL)

  		goto out;

  	spin_lock(&clp->cl_lock);
  	sp = nfs4_insert_state_owner_locked(new);
  	spin_unlock(&clp->cl_lock);

  	if (sp != new)
  		nfs4_free_state_owner(new);

  out:
  	nfs4_gc_state_owners(server);

  	return sp;

  }

  /**
   * nfs4_put_state_owner - Release a nfs4_state_owner
   * @sp: state owner data to release

   *
   * Note that we keep released state owners on an LRU
   * list.
   * This caches valid state owners so that they can be
   * reused, to avoid the OPEN_CONFIRM on minor version 0.
   * It also pins the uniquifier of dropped state owners for
   * a while, to ensure that those state owner names are
   * never reused.

   */

  void nfs4_put_state_owner(struct nfs4_state_owner *sp)
  {

  	struct nfs_server *server = sp->so_server;
  	struct nfs_client *clp = server->nfs_client;

  
  	if (!atomic_dec_and_lock(&sp->so_count, &clp->cl_lock))
  		return;

  	sp->so_expires = jiffies;
  	list_add_tail(&sp->so_lru, &server->state_owners_lru);
  	spin_unlock(&clp->cl_lock);

  }
  
  /**
   * nfs4_purge_state_owners - Release all cached state owners
   * @server: nfs_server with cached state owners to release

   * @head: resulting list of state owners

   *
   * Called at umount time.  Remaining state owners will be on
   * the LRU with ref count of zero.

   * Note that the state owners are not freed, but are added
   * to the list @head, which can later be used as an argument
   * to nfs4_free_state_owners.

   */

  void nfs4_purge_state_owners(struct nfs_server *server, struct list_head *head)

  {
  	struct nfs_client *clp = server->nfs_client;
  	struct nfs4_state_owner *sp, *tmp;

  
  	spin_lock(&clp->cl_lock);
  	list_for_each_entry_safe(sp, tmp, &server->state_owners_lru, so_lru) {

  		list_move(&sp->so_lru, head);

  		nfs4_remove_state_owner_locked(sp);
  	}

  	spin_unlock(&clp->cl_lock);

  }

  /**
   * nfs4_purge_state_owners - Release all cached state owners
   * @head: resulting list of state owners
   *
   * Frees a list of state owners that was generated by
   * nfs4_purge_state_owners
   */
  void nfs4_free_state_owners(struct list_head *head)
  {
  	struct nfs4_state_owner *sp, *tmp;
  
  	list_for_each_entry_safe(sp, tmp, head, so_lru) {

  		list_del(&sp->so_lru);
  		nfs4_free_state_owner(sp);
  	}

  }
  
  static struct nfs4_state *
  nfs4_alloc_open_state(void)
  {
  	struct nfs4_state *state;

  	state = kzalloc(sizeof(*state), GFP_NOFS);

  	if (!state)
  		return NULL;

  	refcount_set(&state->count, 1);

  	INIT_LIST_HEAD(&state->lock_states);

  	spin_lock_init(&state->state_lock);

  	seqlock_init(&state->seqlock);

  	init_waitqueue_head(&state->waitq);

  	return state;
  }

  void

  nfs4_state_set_mode_locked(struct nfs4_state *state, fmode_t fmode)

  {

  	if (state->state == fmode)

  		return;
  	/* NB! List reordering - see the reclaim code for why.  */

  	if ((fmode & FMODE_WRITE) != (state->state & FMODE_WRITE)) {
  		if (fmode & FMODE_WRITE)

  			list_move(&state->open_states, &state->owner->so_states);
  		else
  			list_move_tail(&state->open_states, &state->owner->so_states);
  	}

  	state->state = fmode;

  }

  static struct nfs4_state *

  __nfs4_find_state_byowner(struct inode *inode, struct nfs4_state_owner *owner)
  {
  	struct nfs_inode *nfsi = NFS_I(inode);
  	struct nfs4_state *state;

  	list_for_each_entry_rcu(state, &nfsi->open_states, inode_states) {

  		if (state->owner != owner)

  			continue;

  		if (!nfs4_valid_open_stateid(state))
  			continue;

  		if (refcount_inc_not_zero(&state->count))

  			return state;

  	}
  	return NULL;
  }

  static void
  nfs4_free_open_state(struct nfs4_state *state)
  {

  	kfree_rcu(state, rcu_head);

  }
  
  struct nfs4_state *
  nfs4_get_open_state(struct inode *inode, struct nfs4_state_owner *owner)
  {
  	struct nfs4_state *state, *new;
  	struct nfs_inode *nfsi = NFS_I(inode);

  	rcu_read_lock();

  	state = __nfs4_find_state_byowner(inode, owner);

  	rcu_read_unlock();

  	if (state)
  		goto out;
  	new = nfs4_alloc_open_state();

  	spin_lock(&owner->so_lock);

  	spin_lock(&inode->i_lock);
  	state = __nfs4_find_state_byowner(inode, owner);
  	if (state == NULL && new != NULL) {
  		state = new;

  		state->owner = owner;
  		atomic_inc(&owner->so_count);

  		ihold(inode);
  		state->inode = inode;

  		list_add_rcu(&state->inode_states, &nfsi->open_states);

  		spin_unlock(&inode->i_lock);

  		/* Note: The reclaim code dictates that we add stateless
  		 * and read-only stateids to the end of the list */
  		list_add_tail(&state->open_states, &owner->so_states);
  		spin_unlock(&owner->so_lock);

  	} else {
  		spin_unlock(&inode->i_lock);

  		spin_unlock(&owner->so_lock);

  		if (new)
  			nfs4_free_open_state(new);
  	}
  out:
  	return state;
  }

  void nfs4_put_open_state(struct nfs4_state *state)
  {
  	struct inode *inode = state->inode;
  	struct nfs4_state_owner *owner = state->owner;

  	if (!refcount_dec_and_lock(&state->count, &owner->so_lock))

  		return;

  	spin_lock(&inode->i_lock);

  	list_del_rcu(&state->inode_states);

  	list_del(&state->open_states);

  	spin_unlock(&inode->i_lock);
  	spin_unlock(&owner->so_lock);

  	nfs4_inode_return_delegation_on_close(inode);

  	iput(inode);

  	nfs4_free_open_state(state);
  	nfs4_put_state_owner(owner);
  }
  
  /*

   * Close the current file.

   */

  static void __nfs4_close(struct nfs4_state *state,

  		fmode_t fmode, gfp_t gfp_mask, int wait)

  {

  	struct nfs4_state_owner *owner = state->owner;

  	int call_close = 0;

  	fmode_t newstate;

  
  	atomic_inc(&owner->so_count);

  	/* Protect against nfs4_find_state() */

  	spin_lock(&owner->so_lock);

  	switch (fmode & (FMODE_READ | FMODE_WRITE)) {

  		case FMODE_READ:
  			state->n_rdonly--;
  			break;
  		case FMODE_WRITE:
  			state->n_wronly--;
  			break;
  		case FMODE_READ|FMODE_WRITE:
  			state->n_rdwr--;
  	}

  	newstate = FMODE_READ|FMODE_WRITE;

  	if (state->n_rdwr == 0) {

  		if (state->n_rdonly == 0) {

  			newstate &= ~FMODE_READ;

  			call_close |= test_bit(NFS_O_RDONLY_STATE, &state->flags);
  			call_close |= test_bit(NFS_O_RDWR_STATE, &state->flags);
  		}
  		if (state->n_wronly == 0) {

  			newstate &= ~FMODE_WRITE;

  			call_close |= test_bit(NFS_O_WRONLY_STATE, &state->flags);
  			call_close |= test_bit(NFS_O_RDWR_STATE, &state->flags);
  		}
  		if (newstate == 0)
  			clear_bit(NFS_DELEGATED_STATE, &state->flags);

  	}

  	nfs4_state_set_mode_locked(state, newstate);

  	spin_unlock(&owner->so_lock);

  	if (!call_close) {

  		nfs4_put_open_state(state);
  		nfs4_put_state_owner(owner);

  	} else
  		nfs4_do_close(state, gfp_mask, wait);

  }

  void nfs4_close_state(struct nfs4_state *state, fmode_t fmode)

  {

  	__nfs4_close(state, fmode, GFP_NOFS, 0);

  }

  void nfs4_close_sync(struct nfs4_state *state, fmode_t fmode)

  {

  	__nfs4_close(state, fmode, GFP_KERNEL, 1);

  }
  
  /*
   * Search the state->lock_states for an existing lock_owner

   * that is compatible with either of the given owners.
   * If the second is non-zero, then the first refers to a Posix-lock
   * owner (current->files) and the second refers to a flock/OFD
   * owner (struct file*).  In that case, prefer a match for the first
   * owner.
   * If both sorts of locks are held on the one file we cannot know
   * which stateid was intended to be used, so a "correct" choice cannot
   * be made.  Failing that, a "consistent" choice is preferable.  The
   * consistent choice we make is to prefer the first owner, that of a
   * Posix lock.

   */
  static struct nfs4_lock_state *

  __nfs4_find_lock_state(struct nfs4_state *state,
  		       fl_owner_t fl_owner, fl_owner_t fl_owner2)

  {

  	struct nfs4_lock_state *pos, *ret = NULL;

  	list_for_each_entry(pos, &state->lock_states, ls_locks) {

  		if (pos->ls_owner == fl_owner) {
  			ret = pos;
  			break;
  		}
  		if (pos->ls_owner == fl_owner2)
  			ret = pos;

  	}

  	if (ret)

  		refcount_inc(&ret->ls_count);

  	return ret;

  }

  /*
   * Return a compatible lock_state. If no initialized lock_state structure
   * exists, return an uninitialized one.
   *

   */

  static struct nfs4_lock_state *nfs4_alloc_lock_state(struct nfs4_state *state, fl_owner_t fl_owner)

  {
  	struct nfs4_lock_state *lsp;

  	struct nfs_server *server = state->owner->so_server;

  	lsp = kzalloc(sizeof(*lsp), GFP_NOFS);

  	if (lsp == NULL)
  		return NULL;

  	nfs4_init_seqid_counter(&lsp->ls_seqid);

  	refcount_set(&lsp->ls_count, 1);

  	lsp->ls_state = state;

  	lsp->ls_owner = fl_owner;

  	lsp->ls_seqid.owner_id = ida_simple_get(&server->lockowner_id, 0, 0, GFP_NOFS);
  	if (lsp->ls_seqid.owner_id < 0)

  		goto out_free;

  	INIT_LIST_HEAD(&lsp->ls_locks);

  	return lsp;

  out_free:
  	kfree(lsp);
  	return NULL;

  }

  void nfs4_free_lock_state(struct nfs_server *server, struct nfs4_lock_state *lsp)

  {

  	ida_simple_remove(&server->lockowner_id, lsp->ls_seqid.owner_id);

  	nfs4_destroy_seqid_counter(&lsp->ls_seqid);

  	kfree(lsp);
  }

  /*
   * Return a compatible lock_state. If no initialized lock_state structure
   * exists, return an uninitialized one.
   *

   */

  static struct nfs4_lock_state *nfs4_get_lock_state(struct nfs4_state *state, fl_owner_t owner)

  {

  	struct nfs4_lock_state *lsp, *new = NULL;

  	for(;;) {
  		spin_lock(&state->state_lock);

  		lsp = __nfs4_find_lock_state(state, owner, NULL);

  		if (lsp != NULL)
  			break;
  		if (new != NULL) {

  			list_add(&new->ls_locks, &state->lock_states);
  			set_bit(LK_STATE_IN_USE, &state->flags);
  			lsp = new;
  			new = NULL;
  			break;
  		}
  		spin_unlock(&state->state_lock);

  		new = nfs4_alloc_lock_state(state, owner);

  		if (new == NULL)
  			return NULL;
  	}
  	spin_unlock(&state->state_lock);

  	if (new != NULL)

  		nfs4_free_lock_state(state->owner->so_server, new);

  	return lsp;
  }
  
  /*

   * Release reference to lock_state, and free it if we see that
   * it is no longer in use

   */

  void nfs4_put_lock_state(struct nfs4_lock_state *lsp)

  {

  	struct nfs_server *server;

  	struct nfs4_state *state;

  	if (lsp == NULL)
  		return;
  	state = lsp->ls_state;

  	if (!refcount_dec_and_lock(&lsp->ls_count, &state->state_lock))

  		return;
  	list_del(&lsp->ls_locks);
  	if (list_empty(&state->lock_states))
  		clear_bit(LK_STATE_IN_USE, &state->flags);
  	spin_unlock(&state->state_lock);

  	server = state->owner->so_server;
  	if (test_bit(NFS_LOCK_INITIALIZED, &lsp->ls_flags)) {
  		struct nfs_client *clp = server->nfs_client;
  
  		clp->cl_mvops->free_lock_state(server, lsp);
  	} else

  		nfs4_free_lock_state(server, lsp);

  }

  static void nfs4_fl_copy_lock(struct file_lock *dst, struct file_lock *src)

  {

  	struct nfs4_lock_state *lsp = src->fl_u.nfs4_fl.owner;

  	dst->fl_u.nfs4_fl.owner = lsp;

  	refcount_inc(&lsp->ls_count);

  }

  static void nfs4_fl_release_lock(struct file_lock *fl)

  {

  	nfs4_put_lock_state(fl->fl_u.nfs4_fl.owner);

  }

  static const struct file_lock_operations nfs4_fl_lock_ops = {

  	.fl_copy_lock = nfs4_fl_copy_lock,
  	.fl_release_private = nfs4_fl_release_lock,
  };
  
  int nfs4_set_lock_state(struct nfs4_state *state, struct file_lock *fl)

  {

  	struct nfs4_lock_state *lsp;
  
  	if (fl->fl_ops != NULL)
  		return 0;

  	lsp = nfs4_get_lock_state(state, fl->fl_owner);

  	if (lsp == NULL)
  		return -ENOMEM;
  	fl->fl_u.nfs4_fl.owner = lsp;
  	fl->fl_ops = &nfs4_fl_lock_ops;
  	return 0;

  }

  static int nfs4_copy_lock_stateid(nfs4_stateid *dst,
  		struct nfs4_state *state,

  		const struct nfs_lock_context *l_ctx)

  {

  	struct nfs4_lock_state *lsp;

  	fl_owner_t fl_owner, fl_flock_owner;

  	int ret = -ENOENT;

  	if (l_ctx == NULL)

  		goto out;

  	if (test_bit(LK_STATE_IN_USE, &state->flags) == 0)

  		goto out;

  	fl_owner = l_ctx->lockowner;

  	fl_flock_owner = l_ctx->open_context->flock_owner;

  	spin_lock(&state->state_lock);

  	lsp = __nfs4_find_lock_state(state, fl_owner, fl_flock_owner);

  	if (lsp && test_bit(NFS_LOCK_LOST, &lsp->ls_flags))
  		ret = -EIO;
  	else if (lsp != NULL && test_bit(NFS_LOCK_INITIALIZED, &lsp->ls_flags) != 0) {

  		nfs4_stateid_copy(dst, &lsp->ls_stateid);

  		ret = 0;

  	}

  	spin_unlock(&state->state_lock);

  	nfs4_put_lock_state(lsp);

  out:
  	return ret;
  }

  bool nfs4_copy_open_stateid(nfs4_stateid *dst, struct nfs4_state *state)

  {

  	bool ret;

  	const nfs4_stateid *src;

  	int seq;
  
  	do {

  		ret = false;

  		src = &zero_stateid;

  		seq = read_seqbegin(&state->seqlock);

  		if (test_bit(NFS_OPEN_STATE, &state->flags)) {

  			src = &state->open_stateid;

  			ret = true;
  		}

  		nfs4_stateid_copy(dst, src);

  	} while (read_seqretry(&state->seqlock, seq));

  	return ret;

  }
  
  /*
   * Byte-range lock aware utility to initialize the stateid of read/write
   * requests.
   */

  int nfs4_select_rw_stateid(struct nfs4_state *state,

  		fmode_t fmode, const struct nfs_lock_context *l_ctx,

  		nfs4_stateid *dst, const struct cred **cred)

  {

  	int ret;

  	if (!nfs4_valid_open_stateid(state))
  		return -EIO;

  	if (cred != NULL)
  		*cred = NULL;

  	ret = nfs4_copy_lock_stateid(dst, state, l_ctx);

  	if (ret == -EIO)
  		/* A lost lock - don't even consider delegations */
  		goto out;

  	/* returns true if delegation stateid found and copied */

  	if (nfs4_copy_delegation_stateid(state->inode, fmode, dst, cred)) {

  		ret = 0;

  		goto out;

  	}

  	if (ret != -ENOENT)

  		/* nfs4_copy_delegation_stateid() didn't over-write
  		 * dst, so it still has the lock stateid which we now
  		 * choose to use.
  		 */

  		goto out;

  	ret = nfs4_copy_open_stateid(dst, state) ? 0 : -EAGAIN;

  out:

  	if (nfs_server_capable(state->inode, NFS_CAP_STATEID_NFSV41))
  		dst->seqid = 0;

  	return ret;

  }

  struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter, gfp_t gfp_mask)

  {

  	struct nfs_seqid *new;

  	new = kmalloc(sizeof(*new), gfp_mask);

  	if (new == NULL)
  		return ERR_PTR(-ENOMEM);
  	new->sequence = counter;
  	INIT_LIST_HEAD(&new->list);
  	new->task = NULL;

  	return new;
  }

  void nfs_release_seqid(struct nfs_seqid *seqid)

  {

  	struct nfs_seqid_counter *sequence;

  	if (seqid == NULL || list_empty(&seqid->list))

  		return;
  	sequence = seqid->sequence;
  	spin_lock(&sequence->lock);
  	list_del_init(&seqid->list);
  	if (!list_empty(&sequence->list)) {
  		struct nfs_seqid *next;
  
  		next = list_first_entry(&sequence->list,
  				struct nfs_seqid, list);
  		rpc_wake_up_queued_task(&sequence->wait, next->task);

  	}

  	spin_unlock(&sequence->lock);

  }
  
  void nfs_free_seqid(struct nfs_seqid *seqid)
  {
  	nfs_release_seqid(seqid);

  	kfree(seqid);

  }
  
  /*

   * Increment the seqid if the OPEN/OPEN_DOWNGRADE/CLOSE succeeded, or
   * failed with a seqid incrementing error -

   * see comments nfs4.h:seqid_mutating_error()

   */

  static void nfs_increment_seqid(int status, struct nfs_seqid *seqid)

  {
  	switch (status) {
  		case 0:
  			break;
  		case -NFS4ERR_BAD_SEQID:

  			if (seqid->sequence->flags & NFS_SEQID_CONFIRMED)
  				return;

  			pr_warn_ratelimited("NFS: v4 server returned a bad"

  					" sequence-id error on an"
  					" unconfirmed sequence %p!
  ",

  					seqid->sequence);

  		case -NFS4ERR_STALE_CLIENTID:
  		case -NFS4ERR_STALE_STATEID:
  		case -NFS4ERR_BAD_STATEID:
  		case -NFS4ERR_BADXDR:
  		case -NFS4ERR_RESOURCE:
  		case -NFS4ERR_NOFILEHANDLE:

  		case -NFS4ERR_MOVED:

  			/* Non-seqid mutating errors */
  			return;

  	}

  	/*
  	 * Note: no locking needed as we are guaranteed to be first
  	 * on the sequence list
  	 */
  	seqid->sequence->counter++;
  }
  
  void nfs_increment_open_seqid(int status, struct nfs_seqid *seqid)
  {

  	struct nfs4_state_owner *sp;
  
  	if (seqid == NULL)
  		return;

  	sp = container_of(seqid->sequence, struct nfs4_state_owner, so_seqid);

  	if (status == -NFS4ERR_BAD_SEQID)

  		nfs4_reset_state_owner(sp);

  	if (!nfs4_has_session(sp->so_server->nfs_client))

  		nfs_increment_seqid(status, seqid);

  }
  
  /*

   * Increment the seqid if the LOCK/LOCKU succeeded, or
   * failed with a seqid incrementing error -

   * see comments nfs4.h:seqid_mutating_error()

   */
  void nfs_increment_lock_seqid(int status, struct nfs_seqid *seqid)
  {

  	if (seqid != NULL)
  		nfs_increment_seqid(status, seqid);

  }
  
  int nfs_wait_on_sequence(struct nfs_seqid *seqid, struct rpc_task *task)
  {

  	struct nfs_seqid_counter *sequence;

  	int status = 0;

  	if (seqid == NULL)
  		goto out;
  	sequence = seqid->sequence;

  	spin_lock(&sequence->lock);

  	seqid->task = task;

  	if (list_empty(&seqid->list))
  		list_add_tail(&seqid->list, &sequence->list);
  	if (list_first_entry(&sequence->list, struct nfs_seqid, list) == seqid)
  		goto unlock;

  	rpc_sleep_on(&sequence->wait, task, NULL);

  	status = -EAGAIN;
  unlock:

  	spin_unlock(&sequence->lock);

  out:

  	return status;

  }

  static int nfs4_run_state_manager(void *);

  static void nfs4_clear_state_manager_bit(struct nfs_client *clp)

  {

  	smp_mb__before_atomic();

  	clear_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state);

  	smp_mb__after_atomic();

  	wake_up_bit(&clp->cl_state, NFS4CLNT_MANAGER_RUNNING);

  	rpc_wake_up(&clp->cl_rpcwaitq);
  }

  /*

   * Schedule the nfs_client asynchronous state management routine

   */

  void nfs4_schedule_state_manager(struct nfs_client *clp)

  {

  	struct task_struct *task;

  	char buf[INET6_ADDRSTRLEN + sizeof("-manager") + 1];

  	set_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state);

  	if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0)
  		return;

  	__module_get(THIS_MODULE);

  	refcount_inc(&clp->cl_count);

  
  	/* The rcu_read_lock() is not strictly necessary, as the state
  	 * manager is the only thread that ever changes the rpc_xprt
  	 * after it's initialized.  At this point, we're single threaded. */
  	rcu_read_lock();
  	snprintf(buf, sizeof(buf), "%s-manager",
  			rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR));
  	rcu_read_unlock();

  	task = kthread_run(nfs4_run_state_manager, clp, "%s", buf);

  	if (IS_ERR(task)) {
  		printk(KERN_ERR "%s: kthread_run: %ld
  ",
  			__func__, PTR_ERR(task));
  		nfs4_clear_state_manager_bit(clp);
  		nfs_put_client(clp);
  		module_put(THIS_MODULE);
  	}

  }
  
  /*

   * Schedule a lease recovery attempt

   */

  void nfs4_schedule_lease_recovery(struct nfs_client *clp)

  {
  	if (!clp)
  		return;

  	if (!test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state))
  		set_bit(NFS4CLNT_CHECK_LEASE, &clp->cl_state);

  	dprintk("%s: scheduling lease recovery for server %s
  ", __func__,
  			clp->cl_hostname);

  	nfs4_schedule_state_manager(clp);

  }

  EXPORT_SYMBOL_GPL(nfs4_schedule_lease_recovery);

  /**
   * nfs4_schedule_migration_recovery - trigger migration recovery
   *
   * @server: FSID that is migrating
   *
   * Returns zero if recovery has started, otherwise a negative NFS4ERR
   * value is returned.
   */
  int nfs4_schedule_migration_recovery(const struct nfs_server *server)
  {
  	struct nfs_client *clp = server->nfs_client;
  
  	if (server->fh_expire_type != NFS4_FH_PERSISTENT) {
  		pr_err("NFS: volatile file handles not supported (server %s)
  ",
  				clp->cl_hostname);
  		return -NFS4ERR_IO;
  	}
  
  	if (test_bit(NFS_MIG_FAILED, &server->mig_status))
  		return -NFS4ERR_IO;
  
  	dprintk("%s: scheduling migration recovery for (%llx:%llx) on %s
  ",
  			__func__,
  			(unsigned long long)server->fsid.major,
  			(unsigned long long)server->fsid.minor,
  			clp->cl_hostname);
  
  	set_bit(NFS_MIG_IN_TRANSITION,
  			&((struct nfs_server *)server)->mig_status);
  	set_bit(NFS4CLNT_MOVED, &clp->cl_state);
  
  	nfs4_schedule_state_manager(clp);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(nfs4_schedule_migration_recovery);

  /**
   * nfs4_schedule_lease_moved_recovery - start lease-moved recovery
   *
   * @clp: server to check for moved leases
   *
   */
  void nfs4_schedule_lease_moved_recovery(struct nfs_client *clp)
  {
  	dprintk("%s: scheduling lease-moved recovery for client ID %llx on %s
  ",
  		__func__, clp->cl_clientid, clp->cl_hostname);
  
  	set_bit(NFS4CLNT_LEASE_MOVED, &clp->cl_state);
  	nfs4_schedule_state_manager(clp);
  }
  EXPORT_SYMBOL_GPL(nfs4_schedule_lease_moved_recovery);

  int nfs4_wait_clnt_recover(struct nfs_client *clp)
  {
  	int res;
  
  	might_sleep();

  	refcount_inc(&clp->cl_count);

  	res = wait_on_bit_action(&clp->cl_state, NFS4CLNT_MANAGER_RUNNING,
  				 nfs_wait_bit_killable, TASK_KILLABLE);

  	if (res)

  		goto out;

  	if (clp->cl_cons_state < 0)

  		res = clp->cl_cons_state;
  out:
  	nfs_put_client(clp);
  	return res;

  }
  
  int nfs4_client_recover_expired_lease(struct nfs_client *clp)
  {
  	unsigned int loop;
  	int ret;
  
  	for (loop = NFS4_MAX_LOOP_ON_RECOVER; loop != 0; loop--) {
  		ret = nfs4_wait_clnt_recover(clp);
  		if (ret != 0)
  			break;
  		if (!test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state) &&
  		    !test_bit(NFS4CLNT_CHECK_LEASE,&clp->cl_state))
  			break;
  		nfs4_schedule_state_manager(clp);
  		ret = -EIO;
  	}
  	return ret;
  }

  /*
   * nfs40_handle_cb_pathdown - return all delegations after NFS4ERR_CB_PATH_DOWN
   * @clp: client to process
   *
   * Set the NFS4CLNT_LEASE_EXPIRED state in order to force a
   * resend of the SETCLIENTID and hence re-establish the
   * callback channel. Then return all existing delegations.
   */
  static void nfs40_handle_cb_pathdown(struct nfs_client *clp)
  {
  	set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
  	nfs_expire_all_delegations(clp);

  	dprintk("%s: handling CB_PATHDOWN recovery for server %s
  ", __func__,
  			clp->cl_hostname);

  }

  void nfs4_schedule_path_down_recovery(struct nfs_client *clp)
  {

  	nfs40_handle_cb_pathdown(clp);

  	nfs4_schedule_state_manager(clp);
  }

  static int nfs4_state_mark_reclaim_reboot(struct nfs_client *clp, struct nfs4_state *state)

  {

  	if (!nfs4_valid_open_stateid(state))
  		return 0;

  	set_bit(NFS_STATE_RECLAIM_REBOOT, &state->flags);
  	/* Don't recover state that expired before the reboot */
  	if (test_bit(NFS_STATE_RECLAIM_NOGRACE, &state->flags)) {
  		clear_bit(NFS_STATE_RECLAIM_REBOOT, &state->flags);
  		return 0;
  	}

  	set_bit(NFS_OWNER_RECLAIM_REBOOT, &state->owner->so_flags);

  	set_bit(NFS4CLNT_RECLAIM_REBOOT, &clp->cl_state);
  	return 1;
  }

  int nfs4_state_mark_reclaim_nograce(struct nfs_client *clp, struct nfs4_state *state)

  {

  	if (!nfs4_valid_open_stateid(state))
  		return 0;

  	set_bit(NFS_STATE_RECLAIM_NOGRACE, &state->flags);
  	clear_bit(NFS_STATE_RECLAIM_REBOOT, &state->flags);

  	set_bit(NFS_OWNER_RECLAIM_NOGRACE, &state->owner->so_flags);

  	set_bit(NFS4CLNT_RECLAIM_NOGRACE, &clp->cl_state);
  	return 1;
  }

  int nfs4_schedule_stateid_recovery(const struct nfs_server *server, struct nfs4_state *state)

  {
  	struct nfs_client *clp = server->nfs_client;

  	if (!nfs4_state_mark_reclaim_nograce(clp, state))

  		return -EBADF;

  	nfs_inode_find_delegation_state_and_recover(state->inode,
  			&state->stateid);

  	dprintk("%s: scheduling stateid recovery for server %s
  ", __func__,
  			clp->cl_hostname);

  	nfs4_schedule_state_manager(clp);

  	return 0;

  }

  EXPORT_SYMBOL_GPL(nfs4_schedule_stateid_recovery);

  static struct nfs4_lock_state *
  nfs_state_find_lock_state_by_stateid(struct nfs4_state *state,
  		const nfs4_stateid *stateid)
  {
  	struct nfs4_lock_state *pos;
  
  	list_for_each_entry(pos, &state->lock_states, ls_locks) {
  		if (!test_bit(NFS_LOCK_INITIALIZED, &pos->ls_flags))
  			continue;

  		if (nfs4_stateid_match_or_older(&pos->ls_stateid, stateid))

  			return pos;
  	}
  	return NULL;
  }
  
  static bool nfs_state_lock_state_matches_stateid(struct nfs4_state *state,
  		const nfs4_stateid *stateid)
  {
  	bool found = false;
  
  	if (test_bit(LK_STATE_IN_USE, &state->flags)) {
  		spin_lock(&state->state_lock);
  		if (nfs_state_find_lock_state_by_stateid(state, stateid))
  			found = true;
  		spin_unlock(&state->state_lock);
  	}
  	return found;
  }

  void nfs_inode_find_state_and_recover(struct inode *inode,
  		const nfs4_stateid *stateid)
  {
  	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
  	struct nfs_inode *nfsi = NFS_I(inode);
  	struct nfs_open_context *ctx;
  	struct nfs4_state *state;
  	bool found = false;

  	rcu_read_lock();
  	list_for_each_entry_rcu(ctx, &nfsi->open_files, list) {

  		state = ctx->state;
  		if (state == NULL)
  			continue;

  		if (nfs4_stateid_match_or_older(&state->stateid, stateid) &&

  		    nfs4_state_mark_reclaim_nograce(clp, state)) {

  			found = true;

  			continue;

  		}

  		if (test_bit(NFS_OPEN_STATE, &state->flags) &&
  		    nfs4_stateid_match_or_older(&state->open_stateid, stateid) &&

  		    nfs4_state_mark_reclaim_nograce(clp, state)) {
  			found = true;
  			continue;
  		}