/*
 *  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/smp_lock.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_idmap.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/workqueue.h>
#include <linux/bitops.h>

#include "nfs4_fs.h"
#include "callback.h"
#include "delegation.h"
#include "internal.h"

#define OPENOWNER_POOL_SIZE     8

const nfs4_stateid zero_stateid;

static LIST_HEAD(nfs4_clientid_list);

int nfs4_init_clientid(struct nfs_client *clp, struct rpc_cred *cred)
{
        unsigned short port;
        int status;

        port = nfs_callback_tcpport;
        if (clp->cl_addr.ss_family == AF_INET6)
                port = nfs_callback_tcpport6;

        status = nfs4_proc_setclientid(clp, NFS4_CALLBACK, port, cred);
        if (status == 0)
                status = nfs4_proc_setclientid_confirm(clp, cred);
        if (status == 0)
                nfs4_schedule_state_renewal(clp);
        return status;
}

struct rpc_cred *nfs4_get_machine_cred_locked(struct nfs_client *clp)
{
        struct rpc_cred *cred = NULL;

        if (clp->cl_machine_cred != NULL)
                cred = get_rpccred(clp->cl_machine_cred);
        return cred;
}

static void nfs4_clear_machine_cred(struct nfs_client *clp)
{
        struct rpc_cred *cred;

        spin_lock(&clp->cl_lock);
        cred = clp->cl_machine_cred;
        clp->cl_machine_cred = NULL;
        spin_unlock(&clp->cl_lock);
        if (cred != NULL)
                put_rpccred(cred);
}

struct rpc_cred *nfs4_get_renew_cred_locked(struct nfs_client *clp)
{
        struct nfs4_state_owner *sp;
        struct rb_node *pos;
        struct rpc_cred *cred = NULL;

        for (pos = rb_first(&clp->cl_state_owners); pos != NULL; pos = rb_next(pos)) {
                sp = rb_entry(pos, struct nfs4_state_owner, so_client_node);
                if (list_empty(&sp->so_states))
                        continue;
                cred = get_rpccred(sp->so_cred);
                break;
        }
        return cred;
}

#if defined(CONFIG_NFS_V4_1)

struct rpc_cred *nfs4_get_exchange_id_cred(struct nfs_client *clp)
{
        struct rpc_cred *cred;

        spin_lock(&clp->cl_lock);
        cred = nfs4_get_machine_cred_locked(clp);
        spin_unlock(&clp->cl_lock);
        return cred;
}

#endif /* CONFIG_NFS_V4_1 */

struct rpc_cred *nfs4_get_setclientid_cred(struct nfs_client *clp)
{
        struct nfs4_state_owner *sp;
        struct rb_node *pos;
        struct rpc_cred *cred;

        spin_lock(&clp->cl_lock);
        cred = nfs4_get_machine_cred_locked(clp);
        if (cred != NULL)
                goto out;
        pos = rb_first(&clp->cl_state_owners);
        if (pos != NULL) {
                sp = rb_entry(pos, struct nfs4_state_owner, so_client_node);
                cred = get_rpccred(sp->so_cred);
        }
out:
        spin_unlock(&clp->cl_lock);
        return cred;
}

static void nfs_alloc_unique_id(struct rb_root *root, struct nfs_unique_id *new,
                __u64 minval, int maxbits)
{
        struct rb_node **p, *parent;
        struct nfs_unique_id *pos;
        __u64 mask = ~0ULL;

        if (maxbits < 64)
                mask = (1ULL << maxbits) - 1ULL;

        /* Ensure distribution is more or less flat */
        get_random_bytes(&new->id, sizeof(new->id));
        new->id &= mask;
        if (new->id < minval)
                new->id += minval;
retry:
        p = &root->rb_node;
        parent = NULL;

        while (*p != NULL) {
                parent = *p;
                pos = rb_entry(parent, struct nfs_unique_id, rb_node);

                if (new->id < pos->id)
                        p = &(*p)->rb_left;
                else if (new->id > pos->id)
                        p = &(*p)->rb_right;
                else
                        goto id_exists;
        }
        rb_link_node(&new->rb_node, parent, p);
        rb_insert_color(&new->rb_node, root);
        return;
id_exists:
        for (;;) {
                new->id++;
                if (new->id < minval || (new->id & mask) != new->id) {
                        new->id = minval;
                        break;
                }
                parent = rb_next(parent);
                if (parent == NULL)
                        break;
                pos = rb_entry(parent, struct nfs_unique_id, rb_node);
                if (new->id < pos->id)
                        break;
        }
        goto retry;
}

static void nfs_free_unique_id(struct rb_root *root, struct nfs_unique_id *id)
{
        rb_erase(&id->rb_node, root);
}

static struct nfs4_state_owner *
nfs4_find_state_owner(struct nfs_server *server, struct rpc_cred *cred)
{
        struct nfs_client *clp = server->nfs_client;
        struct rb_node **p = &clp->cl_state_owners.rb_node,
                       *parent = NULL;
        struct nfs4_state_owner *sp, *res = NULL;

        while (*p != NULL) {
                parent = *p;
                sp = rb_entry(parent, struct nfs4_state_owner, so_client_node);

                if (server < sp->so_server) {
                        p = &parent->rb_left;
                        continue;
                }
                if (server > sp->so_server) {
                        p = &parent->rb_right;
                        continue;
                }
                if (cred < sp->so_cred)
                        p = &parent->rb_left;
                else if (cred > sp->so_cred)
                        p = &parent->rb_right;
                else {
                        atomic_inc(&sp->so_count);
                        res = sp;
                        break;
                }
        }
        return res;
}

static struct nfs4_state_owner *
nfs4_insert_state_owner(struct nfs_client *clp, struct nfs4_state_owner *new)
{
        struct rb_node **p = &clp->cl_state_owners.rb_node,
                       *parent = NULL;
        struct nfs4_state_owner *sp;

        while (*p != NULL) {
                parent = *p;
                sp = rb_entry(parent, struct nfs4_state_owner, so_client_node);

                if (new->so_server < sp->so_server) {
                        p = &parent->rb_left;
                        continue;
                }
                if (new->so_server > sp->so_server) {
                        p = &parent->rb_right;
                        continue;
                }
                if (new->so_cred < sp->so_cred)
                        p = &parent->rb_left;
                else if (new->so_cred > sp->so_cred)
                        p = &parent->rb_right;
                else {
                        atomic_inc(&sp->so_count);
                        return sp;
                }
        }
        nfs_alloc_unique_id(&clp->cl_openowner_id, &new->so_owner_id, 1, 64);
        rb_link_node(&new->so_client_node, parent, p);
        rb_insert_color(&new->so_client_node, &clp->cl_state_owners);
        return new;
}

static void
nfs4_remove_state_owner(struct nfs_client *clp, struct nfs4_state_owner *sp)
{
        if (!RB_EMPTY_NODE(&sp->so_client_node))
                rb_erase(&sp->so_client_node, &clp->cl_state_owners);
        nfs_free_unique_id(&clp->cl_openowner_id, &sp->so_owner_id);
}

/*
 * 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(void)
{
        struct nfs4_state_owner *sp;

        sp = kzalloc(sizeof(*sp),GFP_KERNEL);
        if (!sp)
                return NULL;
        spin_lock_init(&sp->so_lock);
        INIT_LIST_HEAD(&sp->so_states);
        INIT_LIST_HEAD(&sp->so_delegations);
        rpc_init_wait_queue(&sp->so_sequence.wait, "Seqid_waitqueue");
        sp->so_seqid.sequence = &sp->so_sequence;
        spin_lock_init(&sp->so_sequence.lock);
        INIT_LIST_HEAD(&sp->so_sequence.list);
        atomic_set(&sp->so_count, 1);
        return sp;
}

static void
nfs4_drop_state_owner(struct nfs4_state_owner *sp)
{
        if (!RB_EMPTY_NODE(&sp->so_client_node)) {
                struct nfs_client *clp = sp->so_client;

                spin_lock(&clp->cl_lock);
                rb_erase(&sp->so_client_node, &clp->cl_state_owners);
                RB_CLEAR_NODE(&sp->so_client_node);
                spin_unlock(&clp->cl_lock);
        }
}

struct nfs4_state_owner *nfs4_get_state_owner(struct nfs_server *server, struct rpc_cred *cred)
{
        struct nfs_client *clp = server->nfs_client;
        struct nfs4_state_owner *sp, *new;

        spin_lock(&clp->cl_lock);
        sp = nfs4_find_state_owner(server, cred);
        spin_unlock(&clp->cl_lock);
        if (sp != NULL)
                return sp;
        new = nfs4_alloc_state_owner();
        if (new == NULL)
                return NULL;
        new->so_client = clp;
        new->so_server = server;
        new->so_cred = cred;
        spin_lock(&clp->cl_lock);
        sp = nfs4_insert_state_owner(clp, new);
        spin_unlock(&clp->cl_lock);
        if (sp == new)
                get_rpccred(cred);
        else {
                rpc_destroy_wait_queue(&new->so_sequence.wait);
                kfree(new);
        }
        return sp;
}

void nfs4_put_state_owner(struct nfs4_state_owner *sp)
{
        struct nfs_client *clp = sp->so_client;
        struct rpc_cred *cred = sp->so_cred;

        if (!atomic_dec_and_lock(&sp->so_count, &clp->cl_lock))
                return;
        nfs4_remove_state_owner(clp, sp);
        spin_unlock(&clp->cl_lock);
        rpc_destroy_wait_queue(&sp->so_sequence.wait);
        put_rpccred(cred);
        kfree(sp);
}

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

        state = kzalloc(sizeof(*state), GFP_KERNEL);
        if (!state)
                return NULL;
        atomic_set(&state->count, 1);
        INIT_LIST_HEAD(&state->lock_states);
        spin_lock_init(&state->state_lock);
        seqlock_init(&state->seqlock);
        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(state, &nfsi->open_states, inode_states) {
                if (state->owner != owner)
                        continue;
                if (atomic_inc_not_zero(&state->count))
                        return state;
        }
        return NULL;
}

static void
nfs4_free_open_state(struct nfs4_state *state)
{
        kfree(state);
}

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);

        spin_lock(&inode->i_lock);
        state = __nfs4_find_state_byowner(inode, owner);
        spin_unlock(&inode->i_lock);
        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);
                list_add(&state->inode_states, &nfsi->open_states);
                state->inode = igrab(inode);
                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 (!atomic_dec_and_lock(&state->count, &owner->so_lock))
                return;
        spin_lock(&inode->i_lock);
        list_del(&state->inode_states);
        list_del(&state->open_states);
        spin_unlock(&inode->i_lock);
        spin_unlock(&owner->so_lock);
        iput(inode);
        nfs4_free_open_state(state);
        nfs4_put_state_owner(owner);
}

/*
 * Close the current file.
 */
static void __nfs4_close(struct path *path, struct nfs4_state *state, fmode_t fmode, 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(path, state, wait);
}

void nfs4_close_state(struct path *path, struct nfs4_state *state, fmode_t fmode)
{
        __nfs4_close(path, state, fmode, 0);
}

void nfs4_close_sync(struct path *path, struct nfs4_state *state, fmode_t fmode)
{
        __nfs4_close(path, state, fmode, 1);
}

/*
 * Search the state->lock_states for an existing lock_owner
 * that is compatible with current->files
 */
static struct nfs4_lock_state *
__nfs4_find_lock_state(struct nfs4_state *state, fl_owner_t fl_owner)
{
        struct nfs4_lock_state *pos;
        list_for_each_entry(pos, &state->lock_states, ls_locks) {
                if (pos->ls_owner != fl_owner)
                        continue;
                atomic_inc(&pos->ls_count);
                return pos;
        }
        return NULL;
}

/*
 * 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_client *clp = state->owner->so_client;

        lsp = kzalloc(sizeof(*lsp), GFP_KERNEL);
        if (lsp == NULL)
                return NULL;
        rpc_init_wait_queue(&lsp->ls_sequence.wait, "lock_seqid_waitqueue");
        spin_lock_init(&lsp->ls_sequence.lock);
        INIT_LIST_HEAD(&lsp->ls_sequence.list);
        lsp->ls_seqid.sequence = &lsp->ls_sequence;
        atomic_set(&lsp->ls_count, 1);
        lsp->ls_state = state;
        lsp->ls_owner = fl_owner;
        spin_lock(&clp->cl_lock);
        nfs_alloc_unique_id(&clp->cl_lockowner_id, &lsp->ls_id, 1, 64);
        spin_unlock(&clp->cl_lock);
        INIT_LIST_HEAD(&lsp->ls_locks);
        return lsp;
}

static void nfs4_free_lock_state(struct nfs4_lock_state *lsp)
{
        struct nfs_client *clp = lsp->ls_state->owner->so_client;

        spin_lock(&clp->cl_lock);
        nfs_free_unique_id(&clp->cl_lockowner_id, &lsp->ls_id);
        spin_unlock(&clp->cl_lock);
        rpc_destroy_wait_queue(&lsp->ls_sequence.wait);
        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);
                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(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 nfs4_state *state;

        if (lsp == NULL)
                return;
        state = lsp->ls_state;
        if (!atomic_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);
        nfs4_free_lock_state(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;
        atomic_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;
}

/*
 * Byte-range lock aware utility to initialize the stateid of read/write
 * requests.
 */
void nfs4_copy_stateid(nfs4_stateid *dst, struct nfs4_state *state, fl_owner_t fl_owner)
{
        struct nfs4_lock_state *lsp;
        int seq;

        do {
                seq = read_seqbegin(&state->seqlock);
                memcpy(dst, &state->stateid, sizeof(*dst));
        } while (read_seqretry(&state->seqlock, seq));
        if (test_bit(LK_STATE_IN_USE, &state->flags) == 0)
                return;

        spin_lock(&state->state_lock);
        lsp = __nfs4_find_lock_state(state, fl_owner);
        if (lsp != NULL && (lsp->ls_flags & NFS_LOCK_INITIALIZED) != 0)
                memcpy(dst, &lsp->ls_stateid, sizeof(*dst));
        spin_unlock(&state->state_lock);
        nfs4_put_lock_state(lsp);
}

struct nfs_seqid *nfs_alloc_seqid(struct nfs_seqid_counter *counter)
{
        struct nfs_seqid *new;

        new = kmalloc(sizeof(*new), GFP_KERNEL);
        if (new != NULL) {
                new->sequence = counter;
                INIT_LIST_HEAD(&new->list);
        }
        return new;
}

void nfs_free_seqid(struct nfs_seqid *seqid)
{
        if (!list_empty(&seqid->list)) {
                struct rpc_sequence *sequence = seqid->sequence->sequence;

                spin_lock(&sequence->lock);
                list_del(&seqid->list);
                spin_unlock(&sequence->lock);
                rpc_wake_up(&sequence->wait);
        }
        kfree(seqid);
}

/*
 * Increment the seqid if the OPEN/OPEN_DOWNGRADE/CLOSE succeeded, or
 * failed with a seqid incrementing error -
 * see comments nfs_fs.h:seqid_mutating_error()
 */
static void nfs_increment_seqid(int status, struct nfs_seqid *seqid)
{
        BUG_ON(list_first_entry(&seqid->sequence->sequence->list, struct nfs_seqid, list) != seqid);
        switch (status) {
                case 0:
                        break;
                case -NFS4ERR_BAD_SEQID:
                        if (seqid->sequence->flags & NFS_SEQID_CONFIRMED)
                                return;
                        printk(KERN_WARNING "NFS: v4 server returned a bad"
                                        " sequence-id error on an"
                                        " unconfirmed sequence %p!\n",
                                        seqid->sequence);
                case -NFS4ERR_STALE_CLIENTID:
                case -NFS4ERR_STALE_STATEID:
                case -NFS4ERR_BAD_STATEID:
                case -NFS4ERR_BADXDR:
                case -NFS4ERR_RESOURCE:
                case -NFS4ERR_NOFILEHANDLE:
                        /* 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 = container_of(seqid->sequence,
                                        struct nfs4_state_owner, so_seqid);
        struct nfs_server *server = sp->so_server;

        if (status == -NFS4ERR_BAD_SEQID)
                nfs4_drop_state_owner(sp);
        if (!nfs4_has_session(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 nfs_fs.h:seqid_mutating_error()
 */
void nfs_increment_lock_seqid(int status, struct nfs_seqid *seqid)
{
        nfs_increment_seqid(status, seqid);
}

int nfs_wait_on_sequence(struct nfs_seqid *seqid, struct rpc_task *task)
{
        struct rpc_sequence *sequence = seqid->sequence->sequence;
        int status = 0;

        spin_lock(&sequence->lock);
        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);
        return status;
}

static int nfs4_run_state_manager(void *);

static void nfs4_clear_state_manager_bit(struct nfs_client *clp)
{
        smp_mb__before_clear_bit();
        clear_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state);
        smp_mb__after_clear_bit();
        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;

        if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0)
                return;
        __module_get(THIS_MODULE);
        atomic_inc(&clp->cl_count);
        task = kthread_run(nfs4_run_state_manager, clp, "%s-manager",
                                rpc_peeraddr2str(clp->cl_rpcclient,
                                                        RPC_DISPLAY_ADDR));
        if (!IS_ERR(task))
                return;
        nfs4_clear_state_manager_bit(clp);
        nfs_put_client(clp);
        module_put(THIS_MODULE);
}

/*
 * Schedule a state recovery attempt
 */
void nfs4_schedule_state_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);
        nfs4_schedule_state_manager(clp);
}

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

        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)
{
        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;
}

static int nfs4_reclaim_locks(struct nfs4_state *state, const struct nfs4_state_recovery_ops *ops)
{
        struct inode *inode = state->inode;
        struct nfs_inode *nfsi = NFS_I(inode);
        struct file_lock *fl;
        int status = 0;

        if (inode->i_flock == NULL)
                return 0;

        /* Guard against delegation returns and new lock/unlock calls */
        down_write(&nfsi->rwsem);
        /* Protect inode->i_flock using the BKL */
        lock_kernel();
        for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
                if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
                        continue;
                if (nfs_file_open_context(fl->fl_file)->state != state)
                        continue;
                unlock_kernel();
                status = ops->recover_lock(state, fl);
                switch (status) {
                        case 0:
                                break;
                        case -ESTALE:
                        case -NFS4ERR_ADMIN_REVOKED:
                        case -NFS4ERR_STALE_STATEID:
                        case -NFS4ERR_BAD_STATEID:
                        case -NFS4ERR_EXPIRED:
                        case -NFS4ERR_NO_GRACE:
                        case -NFS4ERR_STALE_CLIENTID:
                                goto out;
                        default:
                                printk(KERN_ERR "%s: unhandled error %d. Zeroing state\n",
                                                __func__, status);
                        case -ENOMEM:
                        case -NFS4ERR_DENIED:
                        case -NFS4ERR_RECLAIM_BAD:
                        case -NFS4ERR_RECLAIM_CONFLICT:
                                /* kill_proc(fl->fl_pid, SIGLOST, 1); */
                                status = 0;
                }
                lock_kernel();
        }
        unlock_kernel();
out:
        up_write(&nfsi->rwsem);
        return status;
}

static int nfs4_reclaim_open_state(struct nfs4_state_owner *sp, const struct nfs4_state_recovery_ops *ops)
{
        struct nfs4_state *state;
        struct nfs4_lock_state *lock;
        int status = 0;

        /* Note: we rely on the sp->so_states list being ordered 
         * so that we always reclaim open(O_RDWR) and/or open(O_WRITE)
         * states first.
         * This is needed to ensure that the server won't give us any
         * read delegations that we have to return if, say, we are
         * recovering after a network partition or a reboot from a
         * server that doesn't support a grace period.
         */
restart:
        spin_lock(&sp->so_lock);
        list_for_each_entry(state, &sp->so_states, open_states) {
                if (!test_and_clear_bit(ops->state_flag_bit, &state->flags))
                        continue;
                if (state->state == 0)
                        continue;
                atomic_inc(&state->count);
                spin_unlock(&sp->so_lock);
                status = ops->recover_open(sp, state);
                if (status >= 0) {
                        status = nfs4_reclaim_locks(state, ops);
                        if (status >= 0) {
                                list_for_each_entry(lock, &state->lock_states, ls_locks) {
                                        if (!(lock->ls_flags & NFS_LOCK_INITIALIZED))
                                                printk("%s: Lock reclaim failed!\n",
                                                        __func__);
                                }
                                nfs4_put_open_state(state);
                                goto restart;
                        }
                }
                switch (status) {
                        default:
                                printk(KERN_ERR "%s: unhandled error %d. Zeroing state\n",
                                                __func__, status);
                        case -ENOENT:
                        case -ENOMEM:
                        case -ESTALE:
                                /*
                                 * Open state on this file cannot be recovered
                                 * All we can do is revert to using the zero stateid.
                                 */
                                memset(state->stateid.data, 0,
                                        sizeof(state->stateid.data));
                                /* Mark the file as being 'closed' */
                                state->state = 0;
                                break;
                        case -NFS4ERR_ADMIN_REVOKED:
                        case -NFS4ERR_STALE_STATEID:
                        case -NFS4ERR_BAD_STATEID:
                        case -NFS4ERR_RECLAIM_BAD:
                        case -NFS4ERR_RECLAIM_CONFLICT:
                                nfs4_state_mark_reclaim_nograce(sp->so_client, state);
                                break;
                        case -NFS4ERR_EXPIRED:
                        case -NFS4ERR_NO_GRACE:
                                nfs4_state_mark_reclaim_nograce(sp->so_client, state);
                        case -NFS4ERR_STALE_CLIENTID:
                                goto out_err;
                }
                nfs4_put_open_state(state);
                goto restart;
        }
        spin_unlock(&sp->so_lock);
        return 0;
out_err:
        nfs4_put_open_state(state);
        return status;
}

static void nfs4_clear_open_state(struct nfs4_state *state)
{
        struct nfs4_lock_state *lock;

        clear_bit(NFS_DELEGATED_STATE, &state->flags);
        clear_bit(NFS_O_RDONLY_STATE, &state->flags);
        clear_bit(NFS_O_WRONLY_STATE, &state->flags);
        clear_bit(NFS_O_RDWR_STATE, &state->flags);
        list_for_each_entry(lock, &state->lock_states, ls_locks) {
                lock->ls_seqid.flags = 0;
                lock->ls_flags &= ~NFS_LOCK_INITIALIZED;
        }
}

static void nfs4_state_mark_reclaim_helper(struct nfs_client *clp, int (*mark_reclaim)(struct nfs_client *clp, struct nfs4_state *state))
{
        struct nfs4_state_owner *sp;
        struct rb_node *pos;
        struct nfs4_state *state;

        /* Reset all sequence ids to zero */
        for (pos = rb_first(&clp->cl_state_owners); pos != NULL; pos = rb_next(pos)) {
                sp = rb_entry(pos, struct nfs4_state_owner, so_client_node);
                sp->so_seqid.flags = 0;
                spin_lock(&sp->so_lock);
                list_for_each_entry(state, &sp->so_states, open_states) {
                        if (mark_reclaim(clp, state))

                                nfs4_clear_open_state(state);
                }
                spin_unlock(&sp->so_lock);
        }
}

static void nfs4_state_start_reclaim_reboot(struct nfs_client *clp)
{
        /* Mark all delegations for reclaim */
        nfs_delegation_mark_reclaim(clp);
        nfs4_state_mark_reclaim_helper(clp, nfs4_state_mark_reclaim_reboot);
}

static void nfs4_state_end_reclaim_reboot(struct nfs_client *clp)
{
        struct nfs4_state_owner *sp;
        struct rb_node *pos;
        struct nfs4_state *state;

        if (!test_and_clear_bit(NFS4CLNT_RECLAIM_REBOOT, &clp->cl_state))
                return;

        for (pos = rb_first(&clp->cl_state_owners); pos != NULL; pos = rb_next(pos)) {
                sp = rb_entry(pos, struct nfs4_state_owner, so_client_node);
                spin_lock(&sp->so_lock);
                list_for_each_entry(state, &sp->so_states, open_states) {
                        if (!test_and_clear_bit(NFS_STATE_RECLAIM_REBOOT, &state->flags))
                                continue;
                        nfs4_state_mark_reclaim_nograce(clp, state);
                }
                spin_unlock(&sp->so_lock);
        }

        nfs_delegation_reap_unclaimed(clp);
}

static void nfs_delegation_clear_all(struct nfs_client *clp)
{
        nfs_delegation_mark_reclaim(clp);
        nfs_delegation_reap_unclaimed(clp);
}

static void nfs4_state_start_reclaim_nograce(struct nfs_client *clp)
{
        nfs_delegation_clear_all(clp);
        nfs4_state_mark_reclaim_helper(clp, nfs4_state_mark_reclaim_nograce);
}

static void nfs4_state_end_reclaim_nograce(struct nfs_client *clp)
{
        clear_bit(NFS4CLNT_RECLAIM_NOGRACE, &clp->cl_state);
}

static void nfs4_recovery_handle_error(struct nfs_client *clp, int error)
{
        switch (error) {
                case -NFS4ERR_CB_PATH_DOWN:
                        nfs_handle_cb_pathdown(clp);
                        break;
                case -NFS4ERR_STALE_CLIENTID:
                case -NFS4ERR_LEASE_MOVED:
                        set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
                        nfs4_state_start_reclaim_reboot(clp);
                        break;
                case -NFS4ERR_EXPIRED:
                        set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
                        nfs4_state_start_reclaim_nograce(clp);
                case -NFS4ERR_BADSESSION:
                case -NFS4ERR_BADSLOT:
                case -NFS4ERR_BAD_HIGH_SLOT:
                case -NFS4ERR_DEADSESSION:
                case -NFS4ERR_CONN_NOT_BOUND_TO_SESSION:
                case -NFS4ERR_SEQ_FALSE_RETRY:
                case -NFS4ERR_SEQ_MISORDERED:
                        set_bit(NFS4CLNT_SESSION_SETUP, &clp->cl_state);
        }
}

static int nfs4_do_reclaim(struct nfs_client *clp, const struct nfs4_state_recovery_ops *ops)
{
        struct rb_node *pos;
        int status = 0;

restart:
        spin_lock(&clp->cl_lock);
        for (pos = rb_first(&clp->cl_state_owners); pos != NULL; pos = rb_next(pos)) {
                struct nfs4_state_owner *sp = rb_entry(pos, struct nfs4_state_owner, so_client_node);
                if (!test_and_clear_bit(ops->owner_flag_bit, &sp->so_flags))
                        continue;
                atomic_inc(&sp->so_count);
                spin_unlock(&clp->cl_lock);
                status = nfs4_reclaim_open_state(sp, ops);
                if (status < 0) {
                        set_bit(ops->owner_flag_bit, &sp->so_flags);
                        nfs4_put_state_owner(sp);
                        nfs4_recovery_handle_error(clp, status);
                        return status;
                }
                nfs4_put_state_owner(sp);
                goto restart;
        }
        spin_unlock(&clp->cl_lock);
        return status;
}

static int nfs4_check_lease(struct nfs_client *clp)
{
        struct rpc_cred *cred;
        struct nfs4_state_maintenance_ops *ops =
                nfs4_state_renewal_ops[clp->cl_minorversion];
        int status = -NFS4ERR_EXPIRED;

        /* Is the client already known to have an expired lease? */
        if (test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state))
                return 0;
        spin_lock(&clp->cl_lock);
        cred = ops->get_state_renewal_cred_locked(clp);
        spin_unlock(&clp->cl_lock);
        if (cred == NULL) {
                cred = nfs4_get_setclientid_cred(clp);
                if (cred == NULL)
                        goto out;
        }
        status = ops->renew_lease(clp, cred);
        put_rpccred(cred);
out:
        nfs4_recovery_handle_error(clp, status);
        return status;
}

static int nfs4_reclaim_lease(struct nfs_client *clp)
{
        struct rpc_cred *cred;
        struct nfs4_state_recovery_ops *ops =
                nfs4_reboot_recovery_ops[clp->cl_minorversion];
        int status = -ENOENT;

        cred = ops->get_clid_cred(clp);
        if (cred != NULL) {
                status = ops->establish_clid(clp, cred);
                put_rpccred(cred);
                /* Handle case where the user hasn't set up machine creds */
                if (status == -EACCES && cred == clp->cl_machine_cred) {
                        nfs4_clear_machine_cred(clp);
                        status = -EAGAIN;
                }
                if (status == -NFS4ERR_MINOR_VERS_MISMATCH)
                        status = -EPROTONOSUPPORT;
        }
        return status;
}

#ifdef CONFIG_NFS_V4_1
static void nfs4_session_recovery_handle_error(struct nfs_client *clp, int err)
{
        switch (err) {
        case -NFS4ERR_STALE_CLIENTID:
                set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
                set_bit(NFS4CLNT_SESSION_SETUP, &clp->cl_state);
        }
}

static int nfs4_reset_session(struct nfs_client *clp)
{
        int status;

        status = nfs4_proc_destroy_session(clp->cl_session);
        if (status && status != -NFS4ERR_BADSESSION &&
            status != -NFS4ERR_DEADSESSION) {
                nfs4_session_recovery_handle_error(clp, status);
                goto out;
        }

        memset(clp->cl_session->sess_id.data, 0, NFS4_MAX_SESSIONID_LEN);
        status = nfs4_proc_create_session(clp, 1);
        if (status)
                nfs4_session_recovery_handle_error(clp, status);
                /* fall through*/
out:
        /* Wake up the next rpc task even on error */
        rpc_wake_up_next(&clp->cl_session->fc_slot_table.slot_tbl_waitq);
        return status;
}

static int nfs4_initialize_session(struct nfs_client *clp)
{
        int status;

        status = nfs4_proc_create_session(clp, 0);
        if (!status) {
                nfs_mark_client_ready(clp, NFS_CS_READY);
        } else if (status == -NFS4ERR_STALE_CLIENTID) {
                set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
                set_bit(NFS4CLNT_SESSION_SETUP, &clp->cl_state);
        } else {
                nfs_mark_client_ready(clp, status);
        }
        return status;
}
#else /* CONFIG_NFS_V4_1 */
static int nfs4_reset_session(struct nfs_client *clp) { return 0; }
static int nfs4_initialize_session(struct nfs_client *clp) { return 0; }
#endif /* CONFIG_NFS_V4_1 */

/* Set NFS4CLNT_LEASE_EXPIRED for all v4.0 errors and for recoverable errors
 * on EXCHANGE_ID for v4.1
 */
static void nfs4_set_lease_expired(struct nfs_client *clp, int status)
{
        if (nfs4_has_session(clp)) {
                switch (status) {
                case -NFS4ERR_DELAY:
                case -NFS4ERR_CLID_INUSE:
                case -EAGAIN:
                        break;

                case -NFS4ERR_NOT_SAME: /* FixMe: implement recovery
                                         * in nfs4_exchange_id */
                default:
                        return;
                }
        }
        set_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state);
}

static void nfs4_state_manager(struct nfs_client *clp)
{
        int status = 0;

        /* Ensure exclusive access to NFSv4 state */
        for(;;) {
                if (test_and_clear_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state)) {
                        /* We're going to have to re-establish a clientid */
                        status = nfs4_reclaim_lease(clp);
                        if (status) {
                                nfs4_set_lease_expired(clp, status);
                                if (status == -EAGAIN)
                                        continue;
                                if (clp->cl_cons_state ==
                                                        NFS_CS_SESSION_INITING)
                                        nfs_mark_client_ready(clp, status);
                                goto out_error;
                        }
                        clear_bit(NFS4CLNT_CHECK_LEASE, &clp->cl_state);
                }

                if (test_and_clear_bit(NFS4CLNT_CHECK_LEASE, &clp->cl_state)) {
                        status = nfs4_check_lease(clp);
                        if (status != 0)
                                continue;
                }
                /* Initialize or reset the session */
                if (test_and_clear_bit(NFS4CLNT_SESSION_SETUP, &clp->cl_state)
                   && nfs4_has_session(clp)) {
                        if (clp->cl_cons_state == NFS_CS_SESSION_INITING)
                                status = nfs4_initialize_session(clp);
                        else
                                status = nfs4_reset_session(clp);
                        if (status) {
                                if (status == -NFS4ERR_STALE_CLIENTID)
                                        continue;
                                goto out_error;
                        }
                }
                /* First recover reboot state... */
                if (test_and_clear_bit(NFS4CLNT_RECLAIM_REBOOT, &clp->cl_state)) {
                        status = nfs4_do_reclaim(clp,
                                nfs4_reboot_recovery_ops[clp->cl_minorversion]);
                        if (status == -NFS4ERR_STALE_CLIENTID)
                                continue;
                        if (test_bit(NFS4CLNT_SESSION_SETUP, &clp->cl_state))
                                continue;
                        nfs4_state_end_reclaim_reboot(clp);
                        continue;
                }

                /* Now recover expired state... */
                if (test_and_clear_bit(NFS4CLNT_RECLAIM_NOGRACE, &clp->cl_state)) {
                        status = nfs4_do_reclaim(clp,
                                nfs4_nograce_recovery_ops[clp->cl_minorversion]);
                        if (status < 0) {
                                set_bit(NFS4CLNT_RECLAIM_NOGRACE, &clp->cl_state);
                                if (status == -NFS4ERR_STALE_CLIENTID)
                                        continue;
                                if (status == -NFS4ERR_EXPIRED)
                                        continue;
                                if (test_bit(NFS4CLNT_SESSION_SETUP,
                                                                &clp->cl_state))
                                        continue;
                                goto out_error;
                        } else
                                nfs4_state_end_reclaim_nograce(clp);
                        continue;
                }

                if (test_and_clear_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state)) {
                        nfs_client_return_marked_delegations(clp);
                        continue;
                }

                nfs4_clear_state_manager_bit(clp);
                /* Did we race with an attempt to give us more work? */
                if (clp->cl_state == 0)
                        break;
                if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0)
                        break;
        }
        return;
out_error:
        printk(KERN_WARNING "Error: state manager failed on NFSv4 server %s"
                        " with error %d\n", clp->cl_hostname, -status);
        if (test_bit(NFS4CLNT_RECLAIM_REBOOT, &clp->cl_state))
                nfs4_state_end_reclaim_reboot(clp);
        nfs4_clear_state_manager_bit(clp);
}

static int nfs4_run_state_manager(void *ptr)
{
        struct nfs_client *clp = ptr;

        allow_signal(SIGKILL);
        nfs4_state_manager(clp);
        nfs_put_client(clp);
        module_put_and_exit(0);
        return 0;
}

/*
 * Local variables:
 *  c-basic-offset: 8
 * End:
 */