/*
*  Copyright (c) 2001 The Regents of the University of Michigan.
*  All rights reserved.
*
*  Kendrick Smith <kmsmith@umich.edu>
*  Andy Adamson <kandros@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.
*
*/

#include <linux/file.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include <linux/ratelimit.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/addr.h>
#include <linux/jhash.h>
#include <linux/string_helpers.h>
#include "xdr4.h"
#include "xdr4cb.h"
#include "vfs.h"
#include "current_stateid.h"

#include "netns.h"
#include "pnfs.h"
#include "filecache.h"
#include "trace.h"

#define NFSDDBG_FACILITY                NFSDDBG_PROC

#define all_ones {{~0,~0},~0}
static const stateid_t one_stateid = {
        .si_generation = ~0,
        .si_opaque = all_ones,
};
static const stateid_t zero_stateid = {
        /* all fields zero */
};
static const stateid_t currentstateid = {
        .si_generation = 1,
};
static const stateid_t close_stateid = {
        .si_generation = 0xffffffffU,
};

static u64 current_sessionid = 1;

#define ZERO_STATEID(stateid) (!memcmp((stateid), &zero_stateid, sizeof(stateid_t)))
#define ONE_STATEID(stateid)  (!memcmp((stateid), &one_stateid, sizeof(stateid_t)))
#define CURRENT_STATEID(stateid) (!memcmp((stateid), &currentstateid, sizeof(stateid_t)))
#define CLOSE_STATEID(stateid)  (!memcmp((stateid), &close_stateid, sizeof(stateid_t)))

/* forward declarations */
static bool check_for_locks(struct nfs4_file *fp, struct nfs4_lockowner *lowner);
static void nfs4_free_ol_stateid(struct nfs4_stid *stid);
void nfsd4_end_grace(struct nfsd_net *nn);
static void _free_cpntf_state_locked(struct nfsd_net *nn, struct nfs4_cpntf_state *cps);

/* Locking: */

/*
 * Currently used for the del_recall_lru and file hash table.  In an
 * effort to decrease the scope of the client_mutex, this spinlock may
 * eventually cover more:
 */
static DEFINE_SPINLOCK(state_lock);

enum nfsd4_st_mutex_lock_subclass {
        OPEN_STATEID_MUTEX = 0,
        LOCK_STATEID_MUTEX = 1,
};

/*
 * A waitqueue for all in-progress 4.0 CLOSE operations that are waiting for
 * the refcount on the open stateid to drop.
 */
static DECLARE_WAIT_QUEUE_HEAD(close_wq);

/*
 * A waitqueue where a writer to clients/#/ctl destroying a client can
 * wait for cl_rpc_users to drop to 0 and then for the client to be
 * unhashed.
 */
static DECLARE_WAIT_QUEUE_HEAD(expiry_wq);

static struct kmem_cache *client_slab;
static struct kmem_cache *openowner_slab;
static struct kmem_cache *lockowner_slab;
static struct kmem_cache *file_slab;
static struct kmem_cache *stateid_slab;
static struct kmem_cache *deleg_slab;
static struct kmem_cache *odstate_slab;

static void free_session(struct nfsd4_session *);

static const struct nfsd4_callback_ops nfsd4_cb_recall_ops;
static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops;

static bool is_session_dead(struct nfsd4_session *ses)
{
        return ses->se_flags & NFS4_SESSION_DEAD;
}

static __be32 mark_session_dead_locked(struct nfsd4_session *ses, int ref_held_by_me)
{
        if (atomic_read(&ses->se_ref) > ref_held_by_me)
                return nfserr_jukebox;
        ses->se_flags |= NFS4_SESSION_DEAD;
        return nfs_ok;
}

static bool is_client_expired(struct nfs4_client *clp)
{
        return clp->cl_time == 0;
}

static __be32 get_client_locked(struct nfs4_client *clp)
{
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

        lockdep_assert_held(&nn->client_lock);

        if (is_client_expired(clp))
                return nfserr_expired;
        atomic_inc(&clp->cl_rpc_users);
        return nfs_ok;
}

/* must be called under the client_lock */
static inline void
renew_client_locked(struct nfs4_client *clp)
{
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

        if (is_client_expired(clp)) {
                WARN_ON(1);
                printk("%s: client (clientid %08x/%08x) already expired\n",
                        __func__,
                        clp->cl_clientid.cl_boot,
                        clp->cl_clientid.cl_id);
                return;
        }

        list_move_tail(&clp->cl_lru, &nn->client_lru);
        clp->cl_time = ktime_get_boottime_seconds();
}

static void put_client_renew_locked(struct nfs4_client *clp)
{
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

        lockdep_assert_held(&nn->client_lock);

        if (!atomic_dec_and_test(&clp->cl_rpc_users))
                return;
        if (!is_client_expired(clp))
                renew_client_locked(clp);
        else
                wake_up_all(&expiry_wq);
}

static void put_client_renew(struct nfs4_client *clp)
{
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

        if (!atomic_dec_and_lock(&clp->cl_rpc_users, &nn->client_lock))
                return;
        if (!is_client_expired(clp))
                renew_client_locked(clp);
        else
                wake_up_all(&expiry_wq);
        spin_unlock(&nn->client_lock);
}

static __be32 nfsd4_get_session_locked(struct nfsd4_session *ses)
{
        __be32 status;

        if (is_session_dead(ses))
                return nfserr_badsession;
        status = get_client_locked(ses->se_client);
        if (status)
                return status;
        atomic_inc(&ses->se_ref);
        return nfs_ok;
}

static void nfsd4_put_session_locked(struct nfsd4_session *ses)
{
        struct nfs4_client *clp = ses->se_client;
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

        lockdep_assert_held(&nn->client_lock);

        if (atomic_dec_and_test(&ses->se_ref) && is_session_dead(ses))
                free_session(ses);
        put_client_renew_locked(clp);
}

static void nfsd4_put_session(struct nfsd4_session *ses)
{
        struct nfs4_client *clp = ses->se_client;
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

        spin_lock(&nn->client_lock);
        nfsd4_put_session_locked(ses);
        spin_unlock(&nn->client_lock);
}

static struct nfsd4_blocked_lock *
find_blocked_lock(struct nfs4_lockowner *lo, struct knfsd_fh *fh,
                        struct nfsd_net *nn)
{
        struct nfsd4_blocked_lock *cur, *found = NULL;

        spin_lock(&nn->blocked_locks_lock);
        list_for_each_entry(cur, &lo->lo_blocked, nbl_list) {
                if (fh_match(fh, &cur->nbl_fh)) {
                        list_del_init(&cur->nbl_list);
                        list_del_init(&cur->nbl_lru);
                        found = cur;
                        break;
                }
        }
        spin_unlock(&nn->blocked_locks_lock);
        if (found)
                locks_delete_block(&found->nbl_lock);
        return found;
}

static struct nfsd4_blocked_lock *
find_or_allocate_block(struct nfs4_lockowner *lo, struct knfsd_fh *fh,
                        struct nfsd_net *nn)
{
        struct nfsd4_blocked_lock *nbl;

        nbl = find_blocked_lock(lo, fh, nn);
        if (!nbl) {
                nbl= kmalloc(sizeof(*nbl), GFP_KERNEL);
                if (nbl) {
                        INIT_LIST_HEAD(&nbl->nbl_list);
                        INIT_LIST_HEAD(&nbl->nbl_lru);
                        fh_copy_shallow(&nbl->nbl_fh, fh);
                        locks_init_lock(&nbl->nbl_lock);
                        nfsd4_init_cb(&nbl->nbl_cb, lo->lo_owner.so_client,
                                        &nfsd4_cb_notify_lock_ops,
                                        NFSPROC4_CLNT_CB_NOTIFY_LOCK);
                }
        }
        return nbl;
}

static void
free_blocked_lock(struct nfsd4_blocked_lock *nbl)
{
        locks_delete_block(&nbl->nbl_lock);
        locks_release_private(&nbl->nbl_lock);
        kfree(nbl);
}

static void
remove_blocked_locks(struct nfs4_lockowner *lo)
{
        struct nfs4_client *clp = lo->lo_owner.so_client;
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
        struct nfsd4_blocked_lock *nbl;
        LIST_HEAD(reaplist);

        /* Dequeue all blocked locks */
        spin_lock(&nn->blocked_locks_lock);
        while (!list_empty(&lo->lo_blocked)) {
                nbl = list_first_entry(&lo->lo_blocked,
                                        struct nfsd4_blocked_lock,
                                        nbl_list);
                list_del_init(&nbl->nbl_list);
                list_move(&nbl->nbl_lru, &reaplist);
        }
        spin_unlock(&nn->blocked_locks_lock);

        /* Now free them */
        while (!list_empty(&reaplist)) {
                nbl = list_first_entry(&reaplist, struct nfsd4_blocked_lock,
                                        nbl_lru);
                list_del_init(&nbl->nbl_lru);
                free_blocked_lock(nbl);
        }
}

static void
nfsd4_cb_notify_lock_prepare(struct nfsd4_callback *cb)
{
        struct nfsd4_blocked_lock       *nbl = container_of(cb,
                                                struct nfsd4_blocked_lock, nbl_cb);
        locks_delete_block(&nbl->nbl_lock);
}

static int
nfsd4_cb_notify_lock_done(struct nfsd4_callback *cb, struct rpc_task *task)
{
        /*
         * Since this is just an optimization, we don't try very hard if it
         * turns out not to succeed. We'll requeue it on NFS4ERR_DELAY, and
         * just quit trying on anything else.
         */
        switch (task->tk_status) {
        case -NFS4ERR_DELAY:
                rpc_delay(task, 1 * HZ);
                return 0;
        default:
                return 1;
        }
}

static void
nfsd4_cb_notify_lock_release(struct nfsd4_callback *cb)
{
        struct nfsd4_blocked_lock       *nbl = container_of(cb,
                                                struct nfsd4_blocked_lock, nbl_cb);

        free_blocked_lock(nbl);
}

static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops = {
        .prepare        = nfsd4_cb_notify_lock_prepare,
        .done           = nfsd4_cb_notify_lock_done,
        .release        = nfsd4_cb_notify_lock_release,
};

static inline struct nfs4_stateowner *
nfs4_get_stateowner(struct nfs4_stateowner *sop)
{
        atomic_inc(&sop->so_count);
        return sop;
}

static int
same_owner_str(struct nfs4_stateowner *sop, struct xdr_netobj *owner)
{
        return (sop->so_owner.len == owner->len) &&
                0 == memcmp(sop->so_owner.data, owner->data, owner->len);
}

static struct nfs4_openowner *
find_openstateowner_str_locked(unsigned int hashval, struct nfsd4_open *open,
                        struct nfs4_client *clp)
{
        struct nfs4_stateowner *so;

        lockdep_assert_held(&clp->cl_lock);

        list_for_each_entry(so, &clp->cl_ownerstr_hashtbl[hashval],
                            so_strhash) {
                if (!so->so_is_open_owner)
                        continue;
                if (same_owner_str(so, &open->op_owner))
                        return openowner(nfs4_get_stateowner(so));
        }
        return NULL;
}

static struct nfs4_openowner *
find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open,
                        struct nfs4_client *clp)
{
        struct nfs4_openowner *oo;

        spin_lock(&clp->cl_lock);
        oo = find_openstateowner_str_locked(hashval, open, clp);
        spin_unlock(&clp->cl_lock);
        return oo;
}

static inline u32
opaque_hashval(const void *ptr, int nbytes)
{
        unsigned char *cptr = (unsigned char *) ptr;

        u32 x = 0;
        while (nbytes--) {
                x *= 37;
                x += *cptr++;
        }
        return x;
}

static void nfsd4_free_file_rcu(struct rcu_head *rcu)
{
        struct nfs4_file *fp = container_of(rcu, struct nfs4_file, fi_rcu);

        kmem_cache_free(file_slab, fp);
}

void
put_nfs4_file(struct nfs4_file *fi)
{
        might_lock(&state_lock);

        if (refcount_dec_and_lock(&fi->fi_ref, &state_lock)) {
                hlist_del_rcu(&fi->fi_hash);
                spin_unlock(&state_lock);
                WARN_ON_ONCE(!list_empty(&fi->fi_clnt_odstate));
                WARN_ON_ONCE(!list_empty(&fi->fi_delegations));
                call_rcu(&fi->fi_rcu, nfsd4_free_file_rcu);
        }
}

static struct nfsd_file *
__nfs4_get_fd(struct nfs4_file *f, int oflag)
{
        if (f->fi_fds[oflag])
                return nfsd_file_get(f->fi_fds[oflag]);
        return NULL;
}

static struct nfsd_file *
find_writeable_file_locked(struct nfs4_file *f)
{
        struct nfsd_file *ret;

        lockdep_assert_held(&f->fi_lock);

        ret = __nfs4_get_fd(f, O_WRONLY);
        if (!ret)
                ret = __nfs4_get_fd(f, O_RDWR);
        return ret;
}

static struct nfsd_file *
find_writeable_file(struct nfs4_file *f)
{
        struct nfsd_file *ret;

        spin_lock(&f->fi_lock);
        ret = find_writeable_file_locked(f);
        spin_unlock(&f->fi_lock);

        return ret;
}

static struct nfsd_file *
find_readable_file_locked(struct nfs4_file *f)
{
        struct nfsd_file *ret;

        lockdep_assert_held(&f->fi_lock);

        ret = __nfs4_get_fd(f, O_RDONLY);
        if (!ret)
                ret = __nfs4_get_fd(f, O_RDWR);
        return ret;
}

static struct nfsd_file *
find_readable_file(struct nfs4_file *f)
{
        struct nfsd_file *ret;

        spin_lock(&f->fi_lock);
        ret = find_readable_file_locked(f);
        spin_unlock(&f->fi_lock);

        return ret;
}

struct nfsd_file *
find_any_file(struct nfs4_file *f)
{
        struct nfsd_file *ret;

        if (!f)
                return NULL;
        spin_lock(&f->fi_lock);
        ret = __nfs4_get_fd(f, O_RDWR);
        if (!ret) {
                ret = __nfs4_get_fd(f, O_WRONLY);
                if (!ret)
                        ret = __nfs4_get_fd(f, O_RDONLY);
        }
        spin_unlock(&f->fi_lock);
        return ret;
}

static struct nfsd_file *find_deleg_file(struct nfs4_file *f)
{
        struct nfsd_file *ret = NULL;

        spin_lock(&f->fi_lock);
        if (f->fi_deleg_file)
                ret = nfsd_file_get(f->fi_deleg_file);
        spin_unlock(&f->fi_lock);
        return ret;
}

static atomic_long_t num_delegations;
unsigned long max_delegations;

/*
 * Open owner state (share locks)
 */

/* hash tables for lock and open owners */
#define OWNER_HASH_BITS              8
#define OWNER_HASH_SIZE             (1 << OWNER_HASH_BITS)
#define OWNER_HASH_MASK             (OWNER_HASH_SIZE - 1)

static unsigned int ownerstr_hashval(struct xdr_netobj *ownername)
{
        unsigned int ret;

        ret = opaque_hashval(ownername->data, ownername->len);
        return ret & OWNER_HASH_MASK;
}

/* hash table for nfs4_file */
#define FILE_HASH_BITS                   8
#define FILE_HASH_SIZE                  (1 << FILE_HASH_BITS)

static unsigned int nfsd_fh_hashval(struct knfsd_fh *fh)
{
        return jhash2(fh->fh_base.fh_pad, XDR_QUADLEN(fh->fh_size), 0);
}

static unsigned int file_hashval(struct knfsd_fh *fh)
{
        return nfsd_fh_hashval(fh) & (FILE_HASH_SIZE - 1);
}

static struct hlist_head file_hashtbl[FILE_HASH_SIZE];

static void
__nfs4_file_get_access(struct nfs4_file *fp, u32 access)
{
        lockdep_assert_held(&fp->fi_lock);

        if (access & NFS4_SHARE_ACCESS_WRITE)
                atomic_inc(&fp->fi_access[O_WRONLY]);
        if (access & NFS4_SHARE_ACCESS_READ)
                atomic_inc(&fp->fi_access[O_RDONLY]);
}

static __be32
nfs4_file_get_access(struct nfs4_file *fp, u32 access)
{
        lockdep_assert_held(&fp->fi_lock);

        /* Does this access mode make sense? */
        if (access & ~NFS4_SHARE_ACCESS_BOTH)
                return nfserr_inval;

        /* Does it conflict with a deny mode already set? */
        if ((access & fp->fi_share_deny) != 0)
                return nfserr_share_denied;

        __nfs4_file_get_access(fp, access);
        return nfs_ok;
}

static __be32 nfs4_file_check_deny(struct nfs4_file *fp, u32 deny)
{
        /* Common case is that there is no deny mode. */
        if (deny) {
                /* Does this deny mode make sense? */
                if (deny & ~NFS4_SHARE_DENY_BOTH)
                        return nfserr_inval;

                if ((deny & NFS4_SHARE_DENY_READ) &&
                    atomic_read(&fp->fi_access[O_RDONLY]))
                        return nfserr_share_denied;

                if ((deny & NFS4_SHARE_DENY_WRITE) &&
                    atomic_read(&fp->fi_access[O_WRONLY]))
                        return nfserr_share_denied;
        }
        return nfs_ok;
}

static void __nfs4_file_put_access(struct nfs4_file *fp, int oflag)
{
        might_lock(&fp->fi_lock);

        if (atomic_dec_and_lock(&fp->fi_access[oflag], &fp->fi_lock)) {
                struct nfsd_file *f1 = NULL;
                struct nfsd_file *f2 = NULL;

                swap(f1, fp->fi_fds[oflag]);
                if (atomic_read(&fp->fi_access[1 - oflag]) == 0)
                        swap(f2, fp->fi_fds[O_RDWR]);
                spin_unlock(&fp->fi_lock);
                if (f1)
                        nfsd_file_put(f1);
                if (f2)
                        nfsd_file_put(f2);
        }
}

static void nfs4_file_put_access(struct nfs4_file *fp, u32 access)
{
        WARN_ON_ONCE(access & ~NFS4_SHARE_ACCESS_BOTH);

        if (access & NFS4_SHARE_ACCESS_WRITE)
                __nfs4_file_put_access(fp, O_WRONLY);
        if (access & NFS4_SHARE_ACCESS_READ)
                __nfs4_file_put_access(fp, O_RDONLY);
}

/*
 * Allocate a new open/delegation state counter. This is needed for
 * pNFS for proper return on close semantics.
 *
 * Note that we only allocate it for pNFS-enabled exports, otherwise
 * all pointers to struct nfs4_clnt_odstate are always NULL.
 */
static struct nfs4_clnt_odstate *
alloc_clnt_odstate(struct nfs4_client *clp)
{
        struct nfs4_clnt_odstate *co;

        co = kmem_cache_zalloc(odstate_slab, GFP_KERNEL);
        if (co) {
                co->co_client = clp;
                refcount_set(&co->co_odcount, 1);
        }
        return co;
}

static void
hash_clnt_odstate_locked(struct nfs4_clnt_odstate *co)
{
        struct nfs4_file *fp = co->co_file;

        lockdep_assert_held(&fp->fi_lock);
        list_add(&co->co_perfile, &fp->fi_clnt_odstate);
}

static inline void
get_clnt_odstate(struct nfs4_clnt_odstate *co)
{
        if (co)
                refcount_inc(&co->co_odcount);
}

static void
put_clnt_odstate(struct nfs4_clnt_odstate *co)
{
        struct nfs4_file *fp;

        if (!co)
                return;

        fp = co->co_file;
        if (refcount_dec_and_lock(&co->co_odcount, &fp->fi_lock)) {
                list_del(&co->co_perfile);
                spin_unlock(&fp->fi_lock);

                nfsd4_return_all_file_layouts(co->co_client, fp);
                kmem_cache_free(odstate_slab, co);
        }
}

static struct nfs4_clnt_odstate *
find_or_hash_clnt_odstate(struct nfs4_file *fp, struct nfs4_clnt_odstate *new)
{
        struct nfs4_clnt_odstate *co;
        struct nfs4_client *cl;

        if (!new)
                return NULL;

        cl = new->co_client;

        spin_lock(&fp->fi_lock);
        list_for_each_entry(co, &fp->fi_clnt_odstate, co_perfile) {
                if (co->co_client == cl) {
                        get_clnt_odstate(co);
                        goto out;
                }
        }
        co = new;
        co->co_file = fp;
        hash_clnt_odstate_locked(new);
out:
        spin_unlock(&fp->fi_lock);
        return co;
}

struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl, struct kmem_cache *slab,
                                  void (*sc_free)(struct nfs4_stid *))
{
        struct nfs4_stid *stid;
        int new_id;

        stid = kmem_cache_zalloc(slab, GFP_KERNEL);
        if (!stid)
                return NULL;

        idr_preload(GFP_KERNEL);
        spin_lock(&cl->cl_lock);
        /* Reserving 0 for start of file in nfsdfs "states" file: */
        new_id = idr_alloc_cyclic(&cl->cl_stateids, stid, 1, 0, GFP_NOWAIT);
        spin_unlock(&cl->cl_lock);
        idr_preload_end();
        if (new_id < 0)
                goto out_free;

        stid->sc_free = sc_free;
        stid->sc_client = cl;
        stid->sc_stateid.si_opaque.so_id = new_id;
        stid->sc_stateid.si_opaque.so_clid = cl->cl_clientid;
        /* Will be incremented before return to client: */
        refcount_set(&stid->sc_count, 1);
        spin_lock_init(&stid->sc_lock);
        INIT_LIST_HEAD(&stid->sc_cp_list);

        /*
         * It shouldn't be a problem to reuse an opaque stateid value.
         * I don't think it is for 4.1.  But with 4.0 I worry that, for
         * example, a stray write retransmission could be accepted by
         * the server when it should have been rejected.  Therefore,
         * adopt a trick from the sctp code to attempt to maximize the
         * amount of time until an id is reused, by ensuring they always
         * "increase" (mod INT_MAX):
         */
        return stid;
out_free:
        kmem_cache_free(slab, stid);
        return NULL;
}

/*
 * Create a unique stateid_t to represent each COPY.
 */
static int nfs4_init_cp_state(struct nfsd_net *nn, copy_stateid_t *stid,
                              unsigned char sc_type)
{
        int new_id;

        stid->stid.si_opaque.so_clid.cl_boot = (u32)nn->boot_time;
        stid->stid.si_opaque.so_clid.cl_id = nn->s2s_cp_cl_id;
        stid->sc_type = sc_type;

        idr_preload(GFP_KERNEL);
        spin_lock(&nn->s2s_cp_lock);
        new_id = idr_alloc_cyclic(&nn->s2s_cp_stateids, stid, 0, 0, GFP_NOWAIT);
        stid->stid.si_opaque.so_id = new_id;
        spin_unlock(&nn->s2s_cp_lock);
        idr_preload_end();
        if (new_id < 0)
                return 0;
        return 1;
}

int nfs4_init_copy_state(struct nfsd_net *nn, struct nfsd4_copy *copy)
{
        return nfs4_init_cp_state(nn, &copy->cp_stateid, NFS4_COPY_STID);
}

struct nfs4_cpntf_state *nfs4_alloc_init_cpntf_state(struct nfsd_net *nn,
                                                     struct nfs4_stid *p_stid)
{
        struct nfs4_cpntf_state *cps;

        cps = kzalloc(sizeof(struct nfs4_cpntf_state), GFP_KERNEL);
        if (!cps)
                return NULL;
        cps->cpntf_time = ktime_get_boottime_seconds();
        refcount_set(&cps->cp_stateid.sc_count, 1);
        if (!nfs4_init_cp_state(nn, &cps->cp_stateid, NFS4_COPYNOTIFY_STID))
                goto out_free;
        spin_lock(&nn->s2s_cp_lock);
        list_add(&cps->cp_list, &p_stid->sc_cp_list);
        spin_unlock(&nn->s2s_cp_lock);
        return cps;
out_free:
        kfree(cps);
        return NULL;
}

void nfs4_free_copy_state(struct nfsd4_copy *copy)
{
        struct nfsd_net *nn;

        WARN_ON_ONCE(copy->cp_stateid.sc_type != NFS4_COPY_STID);
        nn = net_generic(copy->cp_clp->net, nfsd_net_id);
        spin_lock(&nn->s2s_cp_lock);
        idr_remove(&nn->s2s_cp_stateids,
                   copy->cp_stateid.stid.si_opaque.so_id);
        spin_unlock(&nn->s2s_cp_lock);
}

static void nfs4_free_cpntf_statelist(struct net *net, struct nfs4_stid *stid)
{
        struct nfs4_cpntf_state *cps;
        struct nfsd_net *nn;

        nn = net_generic(net, nfsd_net_id);
        spin_lock(&nn->s2s_cp_lock);
        while (!list_empty(&stid->sc_cp_list)) {
                cps = list_first_entry(&stid->sc_cp_list,
                                       struct nfs4_cpntf_state, cp_list);
                _free_cpntf_state_locked(nn, cps);
        }
        spin_unlock(&nn->s2s_cp_lock);
}

static struct nfs4_ol_stateid * nfs4_alloc_open_stateid(struct nfs4_client *clp)
{
        struct nfs4_stid *stid;

        stid = nfs4_alloc_stid(clp, stateid_slab, nfs4_free_ol_stateid);
        if (!stid)
                return NULL;

        return openlockstateid(stid);
}

static void nfs4_free_deleg(struct nfs4_stid *stid)
{
        kmem_cache_free(deleg_slab, stid);
        atomic_long_dec(&num_delegations);
}

/*
 * When we recall a delegation, we should be careful not to hand it
 * out again straight away.
 * To ensure this we keep a pair of bloom filters ('new' and 'old')
 * in which the filehandles of recalled delegations are "stored".
 * If a filehandle appear in either filter, a delegation is blocked.
 * When a delegation is recalled, the filehandle is stored in the "new"
 * filter.
 * Every 30 seconds we swap the filters and clear the "new" one,
 * unless both are empty of course.
 *
 * Each filter is 256 bits.  We hash the filehandle to 32bit and use the
 * low 3 bytes as hash-table indices.
 *
 * 'blocked_delegations_lock', which is always taken in block_delegations(),
 * is used to manage concurrent access.  Testing does not need the lock
 * except when swapping the two filters.
 */
static DEFINE_SPINLOCK(blocked_delegations_lock);
static struct bloom_pair {
        int     entries, old_entries;
        time64_t swap_time;
        int     new; /* index into 'set' */
        DECLARE_BITMAP(set[2], 256);
} blocked_delegations;

static int delegation_blocked(struct knfsd_fh *fh)
{
        u32 hash;
        struct bloom_pair *bd = &blocked_delegations;

        if (bd->entries == 0)
                return 0;
        if (ktime_get_seconds() - bd->swap_time > 30) {
                spin_lock(&blocked_delegations_lock);
                if (ktime_get_seconds() - bd->swap_time > 30) {
                        bd->entries -= bd->old_entries;
                        bd->old_entries = bd->entries;
                        memset(bd->set[bd->new], 0,
                               sizeof(bd->set[0]));
                        bd->new = 1-bd->new;
                        bd->swap_time = ktime_get_seconds();
                }
                spin_unlock(&blocked_delegations_lock);
        }
        hash = jhash(&fh->fh_base, fh->fh_size, 0);
        if (test_bit(hash&255, bd->set[0]) &&
            test_bit((hash>>8)&255, bd->set[0]) &&
            test_bit((hash>>16)&255, bd->set[0]))
                return 1;

        if (test_bit(hash&255, bd->set[1]) &&
            test_bit((hash>>8)&255, bd->set[1]) &&
            test_bit((hash>>16)&255, bd->set[1]))
                return 1;

        return 0;
}

static void block_delegations(struct knfsd_fh *fh)
{
        u32 hash;
        struct bloom_pair *bd = &blocked_delegations;

        hash = jhash(&fh->fh_base, fh->fh_size, 0);

        spin_lock(&blocked_delegations_lock);
        __set_bit(hash&255, bd->set[bd->new]);
        __set_bit((hash>>8)&255, bd->set[bd->new]);
        __set_bit((hash>>16)&255, bd->set[bd->new]);
        if (bd->entries == 0)
                bd->swap_time = ktime_get_seconds();
        bd->entries += 1;
        spin_unlock(&blocked_delegations_lock);
}

static struct nfs4_delegation *
alloc_init_deleg(struct nfs4_client *clp, struct nfs4_file *fp,
                 struct svc_fh *current_fh,
                 struct nfs4_clnt_odstate *odstate)
{
        struct nfs4_delegation *dp;
        long n;

        dprintk("NFSD alloc_init_deleg\n");
        n = atomic_long_inc_return(&num_delegations);
        if (n < 0 || n > max_delegations)
                goto out_dec;
        if (delegation_blocked(&current_fh->fh_handle))
                goto out_dec;
        dp = delegstateid(nfs4_alloc_stid(clp, deleg_slab, nfs4_free_deleg));
        if (dp == NULL)
                goto out_dec;

        /*
         * delegation seqid's are never incremented.  The 4.1 special
         * meaning of seqid 0 isn't meaningful, really, but let's avoid
         * 0 anyway just for consistency and use 1:
         */
        dp->dl_stid.sc_stateid.si_generation = 1;
        INIT_LIST_HEAD(&dp->dl_perfile);
        INIT_LIST_HEAD(&dp->dl_perclnt);
        INIT_LIST_HEAD(&dp->dl_recall_lru);
        dp->dl_clnt_odstate = odstate;
        get_clnt_odstate(odstate);
        dp->dl_type = NFS4_OPEN_DELEGATE_READ;
        dp->dl_retries = 1;
        nfsd4_init_cb(&dp->dl_recall, dp->dl_stid.sc_client,
                      &nfsd4_cb_recall_ops, NFSPROC4_CLNT_CB_RECALL);
        get_nfs4_file(fp);
        dp->dl_stid.sc_file = fp;
        return dp;
out_dec:
        atomic_long_dec(&num_delegations);
        return NULL;
}

void
nfs4_put_stid(struct nfs4_stid *s)
{
        struct nfs4_file *fp = s->sc_file;
        struct nfs4_client *clp = s->sc_client;

        might_lock(&clp->cl_lock);

        if (!refcount_dec_and_lock(&s->sc_count, &clp->cl_lock)) {
                wake_up_all(&close_wq);
                return;
        }
        idr_remove(&clp->cl_stateids, s->sc_stateid.si_opaque.so_id);
        nfs4_free_cpntf_statelist(clp->net, s);
        spin_unlock(&clp->cl_lock);
        s->sc_free(s);
        if (fp)
                put_nfs4_file(fp);
}

void
nfs4_inc_and_copy_stateid(stateid_t *dst, struct nfs4_stid *stid)
{
        stateid_t *src = &stid->sc_stateid;

        spin_lock(&stid->sc_lock);
        if (unlikely(++src->si_generation == 0))
                src->si_generation = 1;
        memcpy(dst, src, sizeof(*dst));
        spin_unlock(&stid->sc_lock);
}

static void put_deleg_file(struct nfs4_file *fp)
{
        struct nfsd_file *nf = NULL;

        spin_lock(&fp->fi_lock);
        if (--fp->fi_delegees == 0)
                swap(nf, fp->fi_deleg_file);
        spin_unlock(&fp->fi_lock);

        if (nf)
                nfsd_file_put(nf);
}

static void nfs4_unlock_deleg_lease(struct nfs4_delegation *dp)
{
        struct nfs4_file *fp = dp->dl_stid.sc_file;
        struct nfsd_file *nf = fp->fi_deleg_file;

        WARN_ON_ONCE(!fp->fi_delegees);

        vfs_setlease(nf->nf_file, F_UNLCK, NULL, (void **)&dp);
        put_deleg_file(fp);
}

static void destroy_unhashed_deleg(struct nfs4_delegation *dp)
{
        put_clnt_odstate(dp->dl_clnt_odstate);
        nfs4_unlock_deleg_lease(dp);
        nfs4_put_stid(&dp->dl_stid);
}

void nfs4_unhash_stid(struct nfs4_stid *s)
{
        s->sc_type = 0;
}

/**
 * nfs4_delegation_exists - Discover if this delegation already exists
 * @clp:     a pointer to the nfs4_client we're granting a delegation to
 * @fp:      a pointer to the nfs4_file we're granting a delegation on
 *
 * Return:
 *      On success: true iff an existing delegation is found
 */

static bool
nfs4_delegation_exists(struct nfs4_client *clp, struct nfs4_file *fp)
{
        struct nfs4_delegation *searchdp = NULL;
        struct nfs4_client *searchclp = NULL;

        lockdep_assert_held(&state_lock);
        lockdep_assert_held(&fp->fi_lock);

        list_for_each_entry(searchdp, &fp->fi_delegations, dl_perfile) {
                searchclp = searchdp->dl_stid.sc_client;
                if (clp == searchclp) {
                        return true;
                }
        }
        return false;
}

/**
 * hash_delegation_locked - Add a delegation to the appropriate lists
 * @dp:     a pointer to the nfs4_delegation we are adding.
 * @fp:     a pointer to the nfs4_file we're granting a delegation on
 *
 * Return:
 *      On success: NULL if the delegation was successfully hashed.
 *
 *      On error: -EAGAIN if one was previously granted to this
 *                 nfs4_client for this nfs4_file. Delegation is not hashed.
 *
 */

static int
hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp)
{
        struct nfs4_client *clp = dp->dl_stid.sc_client;

        lockdep_assert_held(&state_lock);
        lockdep_assert_held(&fp->fi_lock);

        if (nfs4_delegation_exists(clp, fp))
                return -EAGAIN;
        refcount_inc(&dp->dl_stid.sc_count);
        dp->dl_stid.sc_type = NFS4_DELEG_STID;
        list_add(&dp->dl_perfile, &fp->fi_delegations);
        list_add(&dp->dl_perclnt, &clp->cl_delegations);
        return 0;
}

static bool
unhash_delegation_locked(struct nfs4_delegation *dp)
{
        struct nfs4_file *fp = dp->dl_stid.sc_file;

        lockdep_assert_held(&state_lock);

        if (list_empty(&dp->dl_perfile))
                return false;

        dp->dl_stid.sc_type = NFS4_CLOSED_DELEG_STID;
        /* Ensure that deleg break won't try to requeue it */
        ++dp->dl_time;
        spin_lock(&fp->fi_lock);
        list_del_init(&dp->dl_perclnt);
        list_del_init(&dp->dl_recall_lru);
        list_del_init(&dp->dl_perfile);
        spin_unlock(&fp->fi_lock);
        return true;
}

static void destroy_delegation(struct nfs4_delegation *dp)
{
        bool unhashed;

        spin_lock(&state_lock);
        unhashed = unhash_delegation_locked(dp);
        spin_unlock(&state_lock);
        if (unhashed)
                destroy_unhashed_deleg(dp);
}

static void revoke_delegation(struct nfs4_delegation *dp)
{
        struct nfs4_client *clp = dp->dl_stid.sc_client;

        WARN_ON(!list_empty(&dp->dl_recall_lru));

        if (clp->cl_minorversion) {
                dp->dl_stid.sc_type = NFS4_REVOKED_DELEG_STID;
                refcount_inc(&dp->dl_stid.sc_count);
                spin_lock(&clp->cl_lock);
                list_add(&dp->dl_recall_lru, &clp->cl_revoked);
                spin_unlock(&clp->cl_lock);
        }
        destroy_unhashed_deleg(dp);
}

/* 
 * SETCLIENTID state 
 */

static unsigned int clientid_hashval(u32 id)
{
        return id & CLIENT_HASH_MASK;
}

static unsigned int clientstr_hashval(struct xdr_netobj name)
{
        return opaque_hashval(name.data, 8) & CLIENT_HASH_MASK;
}

/*
 * We store the NONE, READ, WRITE, and BOTH bits separately in the
 * st_{access,deny}_bmap field of the stateid, in order to track not
 * only what share bits are currently in force, but also what
 * combinations of share bits previous opens have used.  This allows us
 * to enforce the recommendation of rfc 3530 14.2.19 that the server
 * return an error if the client attempt to downgrade to a combination
 * of share bits not explicable by closing some of its previous opens.
 *
 * XXX: This enforcement is actually incomplete, since we don't keep
 * track of access/deny bit combinations; so, e.g., we allow:
 *
 *      OPEN allow read, deny write
 *      OPEN allow both, deny none
 *      DOWNGRADE allow read, deny none
 *
 * which we should reject.
 */
static unsigned int
bmap_to_share_mode(unsigned long bmap) {
        int i;
        unsigned int access = 0;

        for (i = 1; i < 4; i++) {
                if (test_bit(i, &bmap))
                        access |= i;
        }
        return access;
}

/* set share access for a given stateid */
static inline void
set_access(u32 access, struct nfs4_ol_stateid *stp)
{
        unsigned char mask = 1 << access;

        WARN_ON_ONCE(access > NFS4_SHARE_ACCESS_BOTH);
        stp->st_access_bmap |= mask;
}

/* clear share access for a given stateid */
static inline void
clear_access(u32 access, struct nfs4_ol_stateid *stp)
{
        unsigned char mask = 1 << access;

        WARN_ON_ONCE(access > NFS4_SHARE_ACCESS_BOTH);
        stp->st_access_bmap &= ~mask;
}

/* test whether a given stateid has access */
static inline bool
test_access(u32 access, struct nfs4_ol_stateid *stp)
{
        unsigned char mask = 1 << access;

        return (bool)(stp->st_access_bmap & mask);
}

/* set share deny for a given stateid */
static inline void
set_deny(u32 deny, struct nfs4_ol_stateid *stp)
{
        unsigned char mask = 1 << deny;

        WARN_ON_ONCE(deny > NFS4_SHARE_DENY_BOTH);
        stp->st_deny_bmap |= mask;
}

/* clear share deny for a given stateid */
static inline void
clear_deny(u32 deny, struct nfs4_ol_stateid *stp)
{
        unsigned char mask = 1 << deny;

        WARN_ON_ONCE(deny > NFS4_SHARE_DENY_BOTH);
        stp->st_deny_bmap &= ~mask;
}

/* test whether a given stateid is denying specific access */
static inline bool
test_deny(u32 deny, struct nfs4_ol_stateid *stp)
{
        unsigned char mask = 1 << deny;

        return (bool)(stp->st_deny_bmap & mask);
}

static int nfs4_access_to_omode(u32 access)
{
        switch (access & NFS4_SHARE_ACCESS_BOTH) {
        case NFS4_SHARE_ACCESS_READ:
                return O_RDONLY;
        case NFS4_SHARE_ACCESS_WRITE:
                return O_WRONLY;
        case NFS4_SHARE_ACCESS_BOTH:
                return O_RDWR;
        }
        WARN_ON_ONCE(1);
        return O_RDONLY;
}

/*
 * A stateid that had a deny mode associated with it is being released
 * or downgraded. Recalculate the deny mode on the file.
 */
static void
recalculate_deny_mode(struct nfs4_file *fp)
{
        struct nfs4_ol_stateid *stp;

        spin_lock(&fp->fi_lock);
        fp->fi_share_deny = 0;
        list_for_each_entry(stp, &fp->fi_stateids, st_perfile)
                fp->fi_share_deny |= bmap_to_share_mode(stp->st_deny_bmap);
        spin_unlock(&fp->fi_lock);
}

static void
reset_union_bmap_deny(u32 deny, struct nfs4_ol_stateid *stp)
{
        int i;
        bool change = false;

        for (i = 1; i < 4; i++) {
                if ((i & deny) != i) {
                        change = true;
                        clear_deny(i, stp);
                }
        }

        /* Recalculate per-file deny mode if there was a change */
        if (change)
                recalculate_deny_mode(stp->st_stid.sc_file);
}

/* release all access and file references for a given stateid */
static void
release_all_access(struct nfs4_ol_stateid *stp)
{
        int i;
        struct nfs4_file *fp = stp->st_stid.sc_file;

        if (fp && stp->st_deny_bmap != 0)
                recalculate_deny_mode(fp);

        for (i = 1; i < 4; i++) {
                if (test_access(i, stp))
                        nfs4_file_put_access(stp->st_stid.sc_file, i);
                clear_access(i, stp);
        }
}

static inline void nfs4_free_stateowner(struct nfs4_stateowner *sop)
{
        kfree(sop->so_owner.data);
        sop->so_ops->so_free(sop);
}

static void nfs4_put_stateowner(struct nfs4_stateowner *sop)
{
        struct nfs4_client *clp = sop->so_client;

        might_lock(&clp->cl_lock);

        if (!atomic_dec_and_lock(&sop->so_count, &clp->cl_lock))
                return;
        sop->so_ops->so_unhash(sop);
        spin_unlock(&clp->cl_lock);
        nfs4_free_stateowner(sop);
}

static bool
nfs4_ol_stateid_unhashed(const struct nfs4_ol_stateid *stp)
{
        return list_empty(&stp->st_perfile);
}

static bool unhash_ol_stateid(struct nfs4_ol_stateid *stp)
{
        struct nfs4_file *fp = stp->st_stid.sc_file;

        lockdep_assert_held(&stp->st_stateowner->so_client->cl_lock);

        if (list_empty(&stp->st_perfile))
                return false;

        spin_lock(&fp->fi_lock);
        list_del_init(&stp->st_perfile);
        spin_unlock(&fp->fi_lock);
        list_del(&stp->st_perstateowner);
        return true;
}

static void nfs4_free_ol_stateid(struct nfs4_stid *stid)
{
        struct nfs4_ol_stateid *stp = openlockstateid(stid);

        put_clnt_odstate(stp->st_clnt_odstate);
        release_all_access(stp);
        if (stp->st_stateowner)
                nfs4_put_stateowner(stp->st_stateowner);
        kmem_cache_free(stateid_slab, stid);
}

static void nfs4_free_lock_stateid(struct nfs4_stid *stid)
{
        struct nfs4_ol_stateid *stp = openlockstateid(stid);
        struct nfs4_lockowner *lo = lockowner(stp->st_stateowner);
        struct nfsd_file *nf;

        nf = find_any_file(stp->st_stid.sc_file);
        if (nf) {
                get_file(nf->nf_file);
                filp_close(nf->nf_file, (fl_owner_t)lo);
                nfsd_file_put(nf);
        }
        nfs4_free_ol_stateid(stid);
}

/*
 * Put the persistent reference to an already unhashed generic stateid, while
 * holding the cl_lock. If it's the last reference, then put it onto the
 * reaplist for later destruction.
 */
static void put_ol_stateid_locked(struct nfs4_ol_stateid *stp,
                                       struct list_head *reaplist)
{
        struct nfs4_stid *s = &stp->st_stid;
        struct nfs4_client *clp = s->sc_client;

        lockdep_assert_held(&clp->cl_lock);

        WARN_ON_ONCE(!list_empty(&stp->st_locks));

        if (!refcount_dec_and_test(&s->sc_count)) {
                wake_up_all(&close_wq);
                return;
        }

        idr_remove(&clp->cl_stateids, s->sc_stateid.si_opaque.so_id);
        list_add(&stp->st_locks, reaplist);
}

static bool unhash_lock_stateid(struct nfs4_ol_stateid *stp)
{
        lockdep_assert_held(&stp->st_stid.sc_client->cl_lock);

        if (!unhash_ol_stateid(stp))
                return false;
        list_del_init(&stp->st_locks);
        nfs4_unhash_stid(&stp->st_stid);
        return true;
}

static void release_lock_stateid(struct nfs4_ol_stateid *stp)
{
        struct nfs4_client *clp = stp->st_stid.sc_client;
        bool unhashed;

        spin_lock(&clp->cl_lock);
        unhashed = unhash_lock_stateid(stp);
        spin_unlock(&clp->cl_lock);
        if (unhashed)
                nfs4_put_stid(&stp->st_stid);
}

static void unhash_lockowner_locked(struct nfs4_lockowner *lo)
{
        struct nfs4_client *clp = lo->lo_owner.so_client;

        lockdep_assert_held(&clp->cl_lock);

        list_del_init(&lo->lo_owner.so_strhash);
}

/*
 * Free a list of generic stateids that were collected earlier after being
 * fully unhashed.
 */
static void
free_ol_stateid_reaplist(struct list_head *reaplist)
{
        struct nfs4_ol_stateid *stp;
        struct nfs4_file *fp;

        might_sleep();

        while (!list_empty(reaplist)) {
                stp = list_first_entry(reaplist, struct nfs4_ol_stateid,
                                       st_locks);
                list_del(&stp->st_locks);
                fp = stp->st_stid.sc_file;
                stp->st_stid.sc_free(&stp->st_stid);
                if (fp)
                        put_nfs4_file(fp);
        }
}

static void release_open_stateid_locks(struct nfs4_ol_stateid *open_stp,
                                       struct list_head *reaplist)
{
        struct nfs4_ol_stateid *stp;

        lockdep_assert_held(&open_stp->st_stid.sc_client->cl_lock);

        while (!list_empty(&open_stp->st_locks)) {
                stp = list_entry(open_stp->st_locks.next,
                                struct nfs4_ol_stateid, st_locks);
                WARN_ON(!unhash_lock_stateid(stp));
                put_ol_stateid_locked(stp, reaplist);
        }
}

static bool unhash_open_stateid(struct nfs4_ol_stateid *stp,
                                struct list_head *reaplist)
{
        lockdep_assert_held(&stp->st_stid.sc_client->cl_lock);

        if (!unhash_ol_stateid(stp))
                return false;
        release_open_stateid_locks(stp, reaplist);
        return true;
}

static void release_open_stateid(struct nfs4_ol_stateid *stp)
{
        LIST_HEAD(reaplist);

        spin_lock(&stp->st_stid.sc_client->cl_lock);
        if (unhash_open_stateid(stp, &reaplist))
                put_ol_stateid_locked(stp, &reaplist);
        spin_unlock(&stp->st_stid.sc_client->cl_lock);
        free_ol_stateid_reaplist(&reaplist);
}

static void unhash_openowner_locked(struct nfs4_openowner *oo)
{
        struct nfs4_client *clp = oo->oo_owner.so_client;

        lockdep_assert_held(&clp->cl_lock);

        list_del_init(&oo->oo_owner.so_strhash);
        list_del_init(&oo->oo_perclient);
}

static void release_last_closed_stateid(struct nfs4_openowner *oo)
{
        struct nfsd_net *nn = net_generic(oo->oo_owner.so_client->net,
                                          nfsd_net_id);
        struct nfs4_ol_stateid *s;

        spin_lock(&nn->client_lock);
        s = oo->oo_last_closed_stid;
        if (s) {
                list_del_init(&oo->oo_close_lru);
                oo->oo_last_closed_stid = NULL;
        }
        spin_unlock(&nn->client_lock);
        if (s)
                nfs4_put_stid(&s->st_stid);
}

static void release_openowner(struct nfs4_openowner *oo)
{
        struct nfs4_ol_stateid *stp;
        struct nfs4_client *clp = oo->oo_owner.so_client;
        struct list_head reaplist;

        INIT_LIST_HEAD(&reaplist);

        spin_lock(&clp->cl_lock);
        unhash_openowner_locked(oo);
        while (!list_empty(&oo->oo_owner.so_stateids)) {
                stp = list_first_entry(&oo->oo_owner.so_stateids,
                                struct nfs4_ol_stateid, st_perstateowner);
                if (unhash_open_stateid(stp, &reaplist))
                        put_ol_stateid_locked(stp, &reaplist);
        }
        spin_unlock(&clp->cl_lock);
        free_ol_stateid_reaplist(&reaplist);
        release_last_closed_stateid(oo);
        nfs4_put_stateowner(&oo->oo_owner);
}

static inline int
hash_sessionid(struct nfs4_sessionid *sessionid)
{
        struct nfsd4_sessionid *sid = (struct nfsd4_sessionid *)sessionid;

        return sid->sequence % SESSION_HASH_SIZE;
}

#ifdef CONFIG_SUNRPC_DEBUG
static inline void
dump_sessionid(const char *fn, struct nfs4_sessionid *sessionid)
{
        u32 *ptr = (u32 *)(&sessionid->data[0]);
        dprintk("%s: %u:%u:%u:%u\n", fn, ptr[0], ptr[1], ptr[2], ptr[3]);
}
#else
static inline void
dump_sessionid(const char *fn, struct nfs4_sessionid *sessionid)
{
}
#endif

/*
 * Bump the seqid on cstate->replay_owner, and clear replay_owner if it
 * won't be used for replay.
 */
void nfsd4_bump_seqid(struct nfsd4_compound_state *cstate, __be32 nfserr)
{
        struct nfs4_stateowner *so = cstate->replay_owner;

        if (nfserr == nfserr_replay_me)
                return;

        if (!seqid_mutating_err(ntohl(nfserr))) {
                nfsd4_cstate_clear_replay(cstate);
                return;
        }
        if (!so)
                return;
        if (so->so_is_open_owner)
                release_last_closed_stateid(openowner(so));
        so->so_seqid++;
        return;
}

static void
gen_sessionid(struct nfsd4_session *ses)
{
        struct nfs4_client *clp = ses->se_client;
        struct nfsd4_sessionid *sid;

        sid = (struct nfsd4_sessionid *)ses->se_sessionid.data;
        sid->clientid = clp->cl_clientid;
        sid->sequence = current_sessionid++;
        sid->reserved = 0;
}

/*
 * The protocol defines ca_maxresponssize_cached to include the size of
 * the rpc header, but all we need to cache is the data starting after
 * the end of the initial SEQUENCE operation--the rest we regenerate
 * each time.  Therefore we can advertise a ca_maxresponssize_cached
 * value that is the number of bytes in our cache plus a few additional
 * bytes.  In order to stay on the safe side, and not promise more than
 * we can cache, those additional bytes must be the minimum possible: 24
 * bytes of rpc header (xid through accept state, with AUTH_NULL
 * verifier), 12 for the compound header (with zero-length tag), and 44
 * for the SEQUENCE op response:
 */
#define NFSD_MIN_HDR_SEQ_SZ  (24 + 12 + 44)

static void
free_session_slots(struct nfsd4_session *ses)
{
        int i;

        for (i = 0; i < ses->se_fchannel.maxreqs; i++) {
                free_svc_cred(&ses->se_slots[i]->sl_cred);
                kfree(ses->se_slots[i]);
        }
}

/*
 * We don't actually need to cache the rpc and session headers, so we
 * can allocate a little less for each slot:
 */
static inline u32 slot_bytes(struct nfsd4_channel_attrs *ca)
{
        u32 size;

        if (ca->maxresp_cached < NFSD_MIN_HDR_SEQ_SZ)
                size = 0;
        else
                size = ca->maxresp_cached - NFSD_MIN_HDR_SEQ_SZ;
        return size + sizeof(struct nfsd4_slot);
}

/*
 * XXX: If we run out of reserved DRC memory we could (up to a point)
 * re-negotiate active sessions and reduce their slot usage to make
 * room for new connections. For now we just fail the create session.
 */
static u32 nfsd4_get_drc_mem(struct nfsd4_channel_attrs *ca, struct nfsd_net *nn)
{
        u32 slotsize = slot_bytes(ca);
        u32 num = ca->maxreqs;
        unsigned long avail, total_avail;
        unsigned int scale_factor;

        spin_lock(&nfsd_drc_lock);
        if (nfsd_drc_max_mem > nfsd_drc_mem_used)
                total_avail = nfsd_drc_max_mem - nfsd_drc_mem_used;
        else
                /* We have handed out more space than we chose in
                 * set_max_drc() to allow.  That isn't really a
                 * problem as long as that doesn't make us think we
                 * have lots more due to integer overflow.
                 */
                total_avail = 0;
        avail = min((unsigned long)NFSD_MAX_MEM_PER_SESSION, total_avail);
        /*
         * Never use more than a fraction of the remaining memory,
         * unless it's the only way to give this client a slot.
         * The chosen fraction is either 1/8 or 1/number of threads,
         * whichever is smaller.  This ensures there are adequate
         * slots to support multiple clients per thread.
         * Give the client one slot even if that would require
         * over-allocation--it is better than failure.
         */
        scale_factor = max_t(unsigned int, 8, nn->nfsd_serv->sv_nrthreads);

        avail = clamp_t(unsigned long, avail, slotsize,
                        total_avail/scale_factor);
        num = min_t(int, num, avail / slotsize);
        num = max_t(int, num, 1);
        nfsd_drc_mem_used += num * slotsize;
        spin_unlock(&nfsd_drc_lock);

        return num;
}

static void nfsd4_put_drc_mem(struct nfsd4_channel_attrs *ca)
{
        int slotsize = slot_bytes(ca);

        spin_lock(&nfsd_drc_lock);
        nfsd_drc_mem_used -= slotsize * ca->maxreqs;
        spin_unlock(&nfsd_drc_lock);
}

static struct nfsd4_session *alloc_session(struct nfsd4_channel_attrs *fattrs,
                                           struct nfsd4_channel_attrs *battrs)
{
        int numslots = fattrs->maxreqs;
        int slotsize = slot_bytes(fattrs);
        struct nfsd4_session *new;
        int mem, i;

        BUILD_BUG_ON(NFSD_MAX_SLOTS_PER_SESSION * sizeof(struct nfsd4_slot *)
                        + sizeof(struct nfsd4_session) > PAGE_SIZE);
        mem = numslots * sizeof(struct nfsd4_slot *);

        new = kzalloc(sizeof(*new) + mem, GFP_KERNEL);
        if (!new)
                return NULL;
        /* allocate each struct nfsd4_slot and data cache in one piece */
        for (i = 0; i < numslots; i++) {
                new->se_slots[i] = kzalloc(slotsize, GFP_KERNEL);
                if (!new->se_slots[i])
                        goto out_free;
        }

        memcpy(&new->se_fchannel, fattrs, sizeof(struct nfsd4_channel_attrs));
        memcpy(&new->se_bchannel, battrs, sizeof(struct nfsd4_channel_attrs));

        return new;
out_free:
        while (i--)
                kfree(new->se_slots[i]);
        kfree(new);
        return NULL;
}

static void free_conn(struct nfsd4_conn *c)
{
        svc_xprt_put(c->cn_xprt);
        kfree(c);
}

static void nfsd4_conn_lost(struct svc_xpt_user *u)
{
        struct nfsd4_conn *c = container_of(u, struct nfsd4_conn, cn_xpt_user);
        struct nfs4_client *clp = c->cn_session->se_client;

        spin_lock(&clp->cl_lock);
        if (!list_empty(&c->cn_persession)) {
                list_del(&c->cn_persession);
                free_conn(c);
        }
        nfsd4_probe_callback(clp);
        spin_unlock(&clp->cl_lock);
}

static struct nfsd4_conn *alloc_conn(struct svc_rqst *rqstp, u32 flags)
{
        struct nfsd4_conn *conn;

        conn = kmalloc(sizeof(struct nfsd4_conn), GFP_KERNEL);
        if (!conn)
                return NULL;
        svc_xprt_get(rqstp->rq_xprt);
        conn->cn_xprt = rqstp->rq_xprt;
        conn->cn_flags = flags;
        INIT_LIST_HEAD(&conn->cn_xpt_user.list);
        return conn;
}

static void __nfsd4_hash_conn(struct nfsd4_conn *conn, struct nfsd4_session *ses)
{
        conn->cn_session = ses;
        list_add(&conn->cn_persession, &ses->se_conns);
}

static void nfsd4_hash_conn(struct nfsd4_conn *conn, struct nfsd4_session *ses)
{
        struct nfs4_client *clp = ses->se_client;

        spin_lock(&clp->cl_lock);
        __nfsd4_hash_conn(conn, ses);
        spin_unlock(&clp->cl_lock);
}

static int nfsd4_register_conn(struct nfsd4_conn *conn)
{
        conn->cn_xpt_user.callback = nfsd4_conn_lost;
        return register_xpt_user(conn->cn_xprt, &conn->cn_xpt_user);
}

static void nfsd4_init_conn(struct svc_rqst *rqstp, struct nfsd4_conn *conn, struct nfsd4_session *ses)
{
        int ret;

        nfsd4_hash_conn(conn, ses);
        ret = nfsd4_register_conn(conn);
        if (ret)
                /* oops; xprt is already down: */
                nfsd4_conn_lost(&conn->cn_xpt_user);
        /* We may have gained or lost a callback channel: */
        nfsd4_probe_callback_sync(ses->se_client);
}

static struct nfsd4_conn *alloc_conn_from_crses(struct svc_rqst *rqstp, struct nfsd4_create_session *cses)
{
        u32 dir = NFS4_CDFC4_FORE;

        if (cses->flags & SESSION4_BACK_CHAN)
                dir |= NFS4_CDFC4_BACK;
        return alloc_conn(rqstp, dir);
}

/* must be called under client_lock */
static void nfsd4_del_conns(struct nfsd4_session *s)
{
        struct nfs4_client *clp = s->se_client;
        struct nfsd4_conn *c;

        spin_lock(&clp->cl_lock);
        while (!list_empty(&s->se_conns)) {
                c = list_first_entry(&s->se_conns, struct nfsd4_conn, cn_persession);
                list_del_init(&c->cn_persession);
                spin_unlock(&clp->cl_lock);

                unregister_xpt_user(c->cn_xprt, &c->cn_xpt_user);
                free_conn(c);

                spin_lock(&clp->cl_lock);
        }
        spin_unlock(&clp->cl_lock);
}

static void __free_session(struct nfsd4_session *ses)
{
        free_session_slots(ses);
        kfree(ses);
}

static void free_session(struct nfsd4_session *ses)
{
        nfsd4_del_conns(ses);
        nfsd4_put_drc_mem(&ses->se_fchannel);
        __free_session(ses);
}

static void init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, struct nfs4_client *clp, struct nfsd4_create_session *cses)
{
        int idx;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        new->se_client = clp;
        gen_sessionid(new);

        INIT_LIST_HEAD(&new->se_conns);

        new->se_cb_seq_nr = 1;
        new->se_flags = cses->flags;
        new->se_cb_prog = cses->callback_prog;
        new->se_cb_sec = cses->cb_sec;
        atomic_set(&new->se_ref, 0);
        idx = hash_sessionid(&new->se_sessionid);
        list_add(&new->se_hash, &nn->sessionid_hashtbl[idx]);
        spin_lock(&clp->cl_lock);
        list_add(&new->se_perclnt, &clp->cl_sessions);
        spin_unlock(&clp->cl_lock);

        {
                struct sockaddr *sa = svc_addr(rqstp);
                /*
                 * This is a little silly; with sessions there's no real
                 * use for the callback address.  Use the peer address
                 * as a reasonable default for now, but consider fixing
                 * the rpc client not to require an address in the
                 * future:
                 */
                rpc_copy_addr((struct sockaddr *)&clp->cl_cb_conn.cb_addr, sa);
                clp->cl_cb_conn.cb_addrlen = svc_addr_len(sa);
        }
}

/* caller must hold client_lock */
static struct nfsd4_session *
__find_in_sessionid_hashtbl(struct nfs4_sessionid *sessionid, struct net *net)
{
        struct nfsd4_session *elem;
        int idx;
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        lockdep_assert_held(&nn->client_lock);

        dump_sessionid(__func__, sessionid);
        idx = hash_sessionid(sessionid);
        /* Search in the appropriate list */
        list_for_each_entry(elem, &nn->sessionid_hashtbl[idx], se_hash) {
                if (!memcmp(elem->se_sessionid.data, sessionid->data,
                            NFS4_MAX_SESSIONID_LEN)) {
                        return elem;
                }
        }

        dprintk("%s: session not found\n", __func__);
        return NULL;
}

static struct nfsd4_session *
find_in_sessionid_hashtbl(struct nfs4_sessionid *sessionid, struct net *net,
                __be32 *ret)
{
        struct nfsd4_session *session;
        __be32 status = nfserr_badsession;

        session = __find_in_sessionid_hashtbl(sessionid, net);
        if (!session)
                goto out;
        status = nfsd4_get_session_locked(session);
        if (status)
                session = NULL;
out:
        *ret = status;
        return session;
}

/* caller must hold client_lock */
static void
unhash_session(struct nfsd4_session *ses)
{
        struct nfs4_client *clp = ses->se_client;
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

        lockdep_assert_held(&nn->client_lock);

        list_del(&ses->se_hash);
        spin_lock(&ses->se_client->cl_lock);
        list_del(&ses->se_perclnt);
        spin_unlock(&ses->se_client->cl_lock);
}

/* SETCLIENTID and SETCLIENTID_CONFIRM Helper functions */
static int
STALE_CLIENTID(clientid_t *clid, struct nfsd_net *nn)
{
        /*
         * We're assuming the clid was not given out from a boot
         * precisely 2^32 (about 136 years) before this one.  That seems
         * a safe assumption:
         */
        if (clid->cl_boot == (u32)nn->boot_time)
                return 0;
        trace_nfsd_clid_stale(clid);
        return 1;
}

/* 
 * XXX Should we use a slab cache ?
 * This type of memory management is somewhat inefficient, but we use it
 * anyway since SETCLIENTID is not a common operation.
 */
static struct nfs4_client *alloc_client(struct xdr_netobj name)
{
        struct nfs4_client *clp;
        int i;

        clp = kmem_cache_zalloc(client_slab, GFP_KERNEL);
        if (clp == NULL)
                return NULL;
        xdr_netobj_dup(&clp->cl_name, &name, GFP_KERNEL);
        if (clp->cl_name.data == NULL)
                goto err_no_name;
        clp->cl_ownerstr_hashtbl = kmalloc_array(OWNER_HASH_SIZE,
                                                 sizeof(struct list_head),
                                                 GFP_KERNEL);
        if (!clp->cl_ownerstr_hashtbl)
                goto err_no_hashtbl;
        for (i = 0; i < OWNER_HASH_SIZE; i++)
                INIT_LIST_HEAD(&clp->cl_ownerstr_hashtbl[i]);
        INIT_LIST_HEAD(&clp->cl_sessions);
        idr_init(&clp->cl_stateids);
        atomic_set(&clp->cl_rpc_users, 0);
        clp->cl_cb_state = NFSD4_CB_UNKNOWN;
        INIT_LIST_HEAD(&clp->cl_idhash);
        INIT_LIST_HEAD(&clp->cl_openowners);
        INIT_LIST_HEAD(&clp->cl_delegations);
        INIT_LIST_HEAD(&clp->cl_lru);
        INIT_LIST_HEAD(&clp->cl_revoked);
#ifdef CONFIG_NFSD_PNFS
        INIT_LIST_HEAD(&clp->cl_lo_states);
#endif
        INIT_LIST_HEAD(&clp->async_copies);
        spin_lock_init(&clp->async_lock);
        spin_lock_init(&clp->cl_lock);
        rpc_init_wait_queue(&clp->cl_cb_waitq, "Backchannel slot table");
        return clp;
err_no_hashtbl:
        kfree(clp->cl_name.data);
err_no_name:
        kmem_cache_free(client_slab, clp);
        return NULL;
}

static void __free_client(struct kref *k)
{
        struct nfsdfs_client *c = container_of(k, struct nfsdfs_client, cl_ref);
        struct nfs4_client *clp = container_of(c, struct nfs4_client, cl_nfsdfs);

        free_svc_cred(&clp->cl_cred);
        kfree(clp->cl_ownerstr_hashtbl);
        kfree(clp->cl_name.data);
        kfree(clp->cl_nii_domain.data);
        kfree(clp->cl_nii_name.data);
        idr_destroy(&clp->cl_stateids);
        kmem_cache_free(client_slab, clp);
}

static void drop_client(struct nfs4_client *clp)
{

        kref_put(&clp->cl_nfsdfs.cl_ref, __free_client);
}

static void
free_client(struct nfs4_client *clp)
{
        while (!list_empty(&clp->cl_sessions)) {
                struct nfsd4_session *ses;
                ses = list_entry(clp->cl_sessions.next, struct nfsd4_session,
                                se_perclnt);
                list_del(&ses->se_perclnt);
                WARN_ON_ONCE(atomic_read(&ses->se_ref));
                free_session(ses);
        }
        rpc_destroy_wait_queue(&clp->cl_cb_waitq);
        if (clp->cl_nfsd_dentry) {
                nfsd_client_rmdir(clp->cl_nfsd_dentry);
                clp->cl_nfsd_dentry = NULL;
                wake_up_all(&expiry_wq);
        }
        drop_client(clp);
}

/* must be called under the client_lock */
static void
unhash_client_locked(struct nfs4_client *clp)
{
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
        struct nfsd4_session *ses;

        lockdep_assert_held(&nn->client_lock);

        /* Mark the client as expired! */
        clp->cl_time = 0;
        /* Make it invisible */
        if (!list_empty(&clp->cl_idhash)) {
                list_del_init(&clp->cl_idhash);
                if (test_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags))
                        rb_erase(&clp->cl_namenode, &nn->conf_name_tree);
                else
                        rb_erase(&clp->cl_namenode, &nn->unconf_name_tree);
        }
        list_del_init(&clp->cl_lru);
        spin_lock(&clp->cl_lock);
        list_for_each_entry(ses, &clp->cl_sessions, se_perclnt)
                list_del_init(&ses->se_hash);
        spin_unlock(&clp->cl_lock);
}

static void
unhash_client(struct nfs4_client *clp)
{
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

        spin_lock(&nn->client_lock);
        unhash_client_locked(clp);
        spin_unlock(&nn->client_lock);
}

static __be32 mark_client_expired_locked(struct nfs4_client *clp)
{
        if (atomic_read(&clp->cl_rpc_users))
                return nfserr_jukebox;
        unhash_client_locked(clp);
        return nfs_ok;
}

static void
__destroy_client(struct nfs4_client *clp)
{
        int i;
        struct nfs4_openowner *oo;
        struct nfs4_delegation *dp;
        struct list_head reaplist;

        INIT_LIST_HEAD(&reaplist);
        spin_lock(&state_lock);
        while (!list_empty(&clp->cl_delegations)) {
                dp = list_entry(clp->cl_delegations.next, struct nfs4_delegation, dl_perclnt);
                WARN_ON(!unhash_delegation_locked(dp));
                list_add(&dp->dl_recall_lru, &reaplist);
        }
        spin_unlock(&state_lock);
        while (!list_empty(&reaplist)) {
                dp = list_entry(reaplist.next, struct nfs4_delegation, dl_recall_lru);
                list_del_init(&dp->dl_recall_lru);
                destroy_unhashed_deleg(dp);
        }
        while (!list_empty(&clp->cl_revoked)) {
                dp = list_entry(clp->cl_revoked.next, struct nfs4_delegation, dl_recall_lru);
                list_del_init(&dp->dl_recall_lru);
                nfs4_put_stid(&dp->dl_stid);
        }
        while (!list_empty(&clp->cl_openowners)) {
                oo = list_entry(clp->cl_openowners.next, struct nfs4_openowner, oo_perclient);
                nfs4_get_stateowner(&oo->oo_owner);
                release_openowner(oo);
        }
        for (i = 0; i < OWNER_HASH_SIZE; i++) {
                struct nfs4_stateowner *so, *tmp;

                list_for_each_entry_safe(so, tmp, &clp->cl_ownerstr_hashtbl[i],
                                         so_strhash) {
                        /* Should be no openowners at this point */
                        WARN_ON_ONCE(so->so_is_open_owner);
                        remove_blocked_locks(lockowner(so));
                }
        }
        nfsd4_return_all_client_layouts(clp);
        nfsd4_shutdown_copy(clp);
        nfsd4_shutdown_callback(clp);
        if (clp->cl_cb_conn.cb_xprt)
                svc_xprt_put(clp->cl_cb_conn.cb_xprt);
        free_client(clp);
        wake_up_all(&expiry_wq);
}

static void
destroy_client(struct nfs4_client *clp)
{
        unhash_client(clp);
        __destroy_client(clp);
}

static void inc_reclaim_complete(struct nfs4_client *clp)
{
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

        if (!nn->track_reclaim_completes)
                return;
        if (!nfsd4_find_reclaim_client(clp->cl_name, nn))
                return;
        if (atomic_inc_return(&nn->nr_reclaim_complete) ==
                        nn->reclaim_str_hashtbl_size) {
                printk(KERN_INFO "NFSD: all clients done reclaiming, ending NFSv4 grace period (net %x)\n",
                                clp->net->ns.inum);
                nfsd4_end_grace(nn);
        }
}

static void expire_client(struct nfs4_client *clp)
{
        unhash_client(clp);
        nfsd4_client_record_remove(clp);
        __destroy_client(clp);
}

static void copy_verf(struct nfs4_client *target, nfs4_verifier *source)
{
        memcpy(target->cl_verifier.data, source->data,
                        sizeof(target->cl_verifier.data));
}

static void copy_clid(struct nfs4_client *target, struct nfs4_client *source)
{
        target->cl_clientid.cl_boot = source->cl_clientid.cl_boot; 
        target->cl_clientid.cl_id = source->cl_clientid.cl_id; 
}

static int copy_cred(struct svc_cred *target, struct svc_cred *source)
{
        target->cr_principal = kstrdup(source->cr_principal, GFP_KERNEL);
        target->cr_raw_principal = kstrdup(source->cr_raw_principal,
                                                                GFP_KERNEL);
        target->cr_targ_princ = kstrdup(source->cr_targ_princ, GFP_KERNEL);
        if ((source->cr_principal && !target->cr_principal) ||
            (source->cr_raw_principal && !target->cr_raw_principal) ||
            (source->cr_targ_princ && !target->cr_targ_princ))
                return -ENOMEM;

        target->cr_flavor = source->cr_flavor;
        target->cr_uid = source->cr_uid;
        target->cr_gid = source->cr_gid;
        target->cr_group_info = source->cr_group_info;
        get_group_info(target->cr_group_info);
        target->cr_gss_mech = source->cr_gss_mech;
        if (source->cr_gss_mech)
                gss_mech_get(source->cr_gss_mech);
        return 0;
}

static int
compare_blob(const struct xdr_netobj *o1, const struct xdr_netobj *o2)
{
        if (o1->len < o2->len)
                return -1;
        if (o1->len > o2->len)
                return 1;
        return memcmp(o1->data, o2->data, o1->len);
}

static int
same_verf(nfs4_verifier *v1, nfs4_verifier *v2)
{
        return 0 == memcmp(v1->data, v2->data, sizeof(v1->data));
}

static int
same_clid(clientid_t *cl1, clientid_t *cl2)
{
        return (cl1->cl_boot == cl2->cl_boot) && (cl1->cl_id == cl2->cl_id);
}

static bool groups_equal(struct group_info *g1, struct group_info *g2)
{
        int i;

        if (g1->ngroups != g2->ngroups)
                return false;
        for (i=0; i<g1->ngroups; i++)
                if (!gid_eq(g1->gid[i], g2->gid[i]))
                        return false;
        return true;
}

/*
 * RFC 3530 language requires clid_inuse be returned when the
 * "principal" associated with a requests differs from that previously
 * used.  We use uid, gid's, and gss principal string as our best
 * approximation.  We also don't want to allow non-gss use of a client
 * established using gss: in theory cr_principal should catch that
 * change, but in practice cr_principal can be null even in the gss case
 * since gssd doesn't always pass down a principal string.
 */
static bool is_gss_cred(struct svc_cred *cr)
{
        /* Is cr_flavor one of the gss "pseudoflavors"?: */
        return (cr->cr_flavor > RPC_AUTH_MAXFLAVOR);
}


static bool
same_creds(struct svc_cred *cr1, struct svc_cred *cr2)
{
        if ((is_gss_cred(cr1) != is_gss_cred(cr2))
                || (!uid_eq(cr1->cr_uid, cr2->cr_uid))
                || (!gid_eq(cr1->cr_gid, cr2->cr_gid))
                || !groups_equal(cr1->cr_group_info, cr2->cr_group_info))
                return false;
        /* XXX: check that cr_targ_princ fields match ? */
        if (cr1->cr_principal == cr2->cr_principal)
                return true;
        if (!cr1->cr_principal || !cr2->cr_principal)
                return false;
        return 0 == strcmp(cr1->cr_principal, cr2->cr_principal);
}

static bool svc_rqst_integrity_protected(struct svc_rqst *rqstp)
{
        struct svc_cred *cr = &rqstp->rq_cred;
        u32 service;

        if (!cr->cr_gss_mech)
                return false;
        service = gss_pseudoflavor_to_service(cr->cr_gss_mech, cr->cr_flavor);
        return service == RPC_GSS_SVC_INTEGRITY ||
               service == RPC_GSS_SVC_PRIVACY;
}

bool nfsd4_mach_creds_match(struct nfs4_client *cl, struct svc_rqst *rqstp)
{
        struct svc_cred *cr = &rqstp->rq_cred;

        if (!cl->cl_mach_cred)
                return true;
        if (cl->cl_cred.cr_gss_mech != cr->cr_gss_mech)
                return false;
        if (!svc_rqst_integrity_protected(rqstp))
                return false;
        if (cl->cl_cred.cr_raw_principal)
                return 0 == strcmp(cl->cl_cred.cr_raw_principal,
                                                cr->cr_raw_principal);
        if (!cr->cr_principal)
                return false;
        return 0 == strcmp(cl->cl_cred.cr_principal, cr->cr_principal);
}

static void gen_confirm(struct nfs4_client *clp, struct nfsd_net *nn)
{
        __be32 verf[2];

        /*
         * This is opaque to client, so no need to byte-swap. Use
         * __force to keep sparse happy
         */
        verf[0] = (__force __be32)(u32)ktime_get_real_seconds();
        verf[1] = (__force __be32)nn->clverifier_counter++;
        memcpy(clp->cl_confirm.data, verf, sizeof(clp->cl_confirm.data));
}

static void gen_clid(struct nfs4_client *clp, struct nfsd_net *nn)
{
        clp->cl_clientid.cl_boot = (u32)nn->boot_time;
        clp->cl_clientid.cl_id = nn->clientid_counter++;
        gen_confirm(clp, nn);
}

static struct nfs4_stid *
find_stateid_locked(struct nfs4_client *cl, stateid_t *t)
{
        struct nfs4_stid *ret;

        ret = idr_find(&cl->cl_stateids, t->si_opaque.so_id);
        if (!ret || !ret->sc_type)
                return NULL;
        return ret;
}

static struct nfs4_stid *
find_stateid_by_type(struct nfs4_client *cl, stateid_t *t, char typemask)
{
        struct nfs4_stid *s;

        spin_lock(&cl->cl_lock);
        s = find_stateid_locked(cl, t);
        if (s != NULL) {
                if (typemask & s->sc_type)
                        refcount_inc(&s->sc_count);
                else
                        s = NULL;
        }
        spin_unlock(&cl->cl_lock);
        return s;
}

static struct nfs4_client *get_nfsdfs_clp(struct inode *inode)
{
        struct nfsdfs_client *nc;
        nc = get_nfsdfs_client(inode);
        if (!nc)
                return NULL;
        return container_of(nc, struct nfs4_client, cl_nfsdfs);
}

static void seq_quote_mem(struct seq_file *m, char *data, int len)
{
        seq_printf(m, "\"");
        seq_escape_mem_ascii(m, data, len);
        seq_printf(m, "\"");
}

static int client_info_show(struct seq_file *m, void *v)
{
        struct inode *inode = m->private;
        struct nfs4_client *clp;
        u64 clid;

        clp = get_nfsdfs_clp(inode);
        if (!clp)
                return -ENXIO;
        memcpy(&clid, &clp->cl_clientid, sizeof(clid));
        seq_printf(m, "clientid: 0x%llx\n", clid);
        seq_printf(m, "address: \"%pISpc\"\n", (struct sockaddr *)&clp->cl_addr);
        seq_printf(m, "name: ");
        seq_quote_mem(m, clp->cl_name.data, clp->cl_name.len);
        seq_printf(m, "\nminor version: %d\n", clp->cl_minorversion);
        if (clp->cl_nii_domain.data) {
                seq_printf(m, "Implementation domain: ");
                seq_quote_mem(m, clp->cl_nii_domain.data,
                                        clp->cl_nii_domain.len);
                seq_printf(m, "\nImplementation name: ");
                seq_quote_mem(m, clp->cl_nii_name.data, clp->cl_nii_name.len);
                seq_printf(m, "\nImplementation time: [%lld, %ld]\n",
                        clp->cl_nii_time.tv_sec, clp->cl_nii_time.tv_nsec);
        }
        drop_client(clp);

        return 0;
}

static int client_info_open(struct inode *inode, struct file *file)
{
        return single_open(file, client_info_show, inode);
}

static const struct file_operations client_info_fops = {
        .open           = client_info_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

static void *states_start(struct seq_file *s, loff_t *pos)
        __acquires(&clp->cl_lock)
{
        struct nfs4_client *clp = s->private;
        unsigned long id = *pos;
        void *ret;

        spin_lock(&clp->cl_lock);
        ret = idr_get_next_ul(&clp->cl_stateids, &id);
        *pos = id;
        return ret;
}

static void *states_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct nfs4_client *clp = s->private;
        unsigned long id = *pos;
        void *ret;

        id = *pos;
        id++;
        ret = idr_get_next_ul(&clp->cl_stateids, &id);
        *pos = id;
        return ret;
}

static void states_stop(struct seq_file *s, void *v)
        __releases(&clp->cl_lock)
{
        struct nfs4_client *clp = s->private;

        spin_unlock(&clp->cl_lock);
}

static void nfs4_show_fname(struct seq_file *s, struct nfsd_file *f)
{
         seq_printf(s, "filename: \"%pD2\"", f->nf_file);
}

static void nfs4_show_superblock(struct seq_file *s, struct nfsd_file *f)
{
        struct inode *inode = f->nf_inode;

        seq_printf(s, "superblock: \"%02x:%02x:%ld\"",
                                        MAJOR(inode->i_sb->s_dev),
                                         MINOR(inode->i_sb->s_dev),
                                         inode->i_ino);
}

static void nfs4_show_owner(struct seq_file *s, struct nfs4_stateowner *oo)
{
        seq_printf(s, "owner: ");
        seq_quote_mem(s, oo->so_owner.data, oo->so_owner.len);
}

static void nfs4_show_stateid(struct seq_file *s, stateid_t *stid)
{
        seq_printf(s, "0x%.8x", stid->si_generation);
        seq_printf(s, "%12phN", &stid->si_opaque);
}

static int nfs4_show_open(struct seq_file *s, struct nfs4_stid *st)
{
        struct nfs4_ol_stateid *ols;
        struct nfs4_file *nf;
        struct nfsd_file *file;
        struct nfs4_stateowner *oo;
        unsigned int access, deny;

        if (st->sc_type != NFS4_OPEN_STID && st->sc_type != NFS4_LOCK_STID)
                return 0; /* XXX: or SEQ_SKIP? */
        ols = openlockstateid(st);
        oo = ols->st_stateowner;
        nf = st->sc_file;
        file = find_any_file(nf);
        if (!file)
                return 0;

        seq_printf(s, "- ");
        nfs4_show_stateid(s, &st->sc_stateid);
        seq_printf(s, ": { type: open, ");

        access = bmap_to_share_mode(ols->st_access_bmap);
        deny   = bmap_to_share_mode(ols->st_deny_bmap);

        seq_printf(s, "access: %s%s, ",
                access & NFS4_SHARE_ACCESS_READ ? "r" : "-",
                access & NFS4_SHARE_ACCESS_WRITE ? "w" : "-");
        seq_printf(s, "deny: %s%s, ",
                deny & NFS4_SHARE_ACCESS_READ ? "r" : "-",
                deny & NFS4_SHARE_ACCESS_WRITE ? "w" : "-");

        nfs4_show_superblock(s, file);
        seq_printf(s, ", ");
        nfs4_show_fname(s, file);
        seq_printf(s, ", ");
        nfs4_show_owner(s, oo);
        seq_printf(s, " }\n");
        nfsd_file_put(file);

        return 0;
}

static int nfs4_show_lock(struct seq_file *s, struct nfs4_stid *st)
{
        struct nfs4_ol_stateid *ols;
        struct nfs4_file *nf;
        struct nfsd_file *file;
        struct nfs4_stateowner *oo;

        ols = openlockstateid(st);
        oo = ols->st_stateowner;
        nf = st->sc_file;
        file = find_any_file(nf);
        if (!file)
                return 0;

        seq_printf(s, "- ");
        nfs4_show_stateid(s, &st->sc_stateid);
        seq_printf(s, ": { type: lock, ");

        /*
         * Note: a lock stateid isn't really the same thing as a lock,
         * it's the locking state held by one owner on a file, and there
         * may be multiple (or no) lock ranges associated with it.
         * (Same for the matter is true of open stateids.)
         */

        nfs4_show_superblock(s, file);
        /* XXX: open stateid? */
        seq_printf(s, ", ");
        nfs4_show_fname(s, file);
        seq_printf(s, ", ");
        nfs4_show_owner(s, oo);
        seq_printf(s, " }\n");
        nfsd_file_put(file);

        return 0;
}

static int nfs4_show_deleg(struct seq_file *s, struct nfs4_stid *st)
{
        struct nfs4_delegation *ds;
        struct nfs4_file *nf;
        struct nfsd_file *file;

        ds = delegstateid(st);
        nf = st->sc_file;
        file = find_deleg_file(nf);
        if (!file)
                return 0;

        seq_printf(s, "- ");
        nfs4_show_stateid(s, &st->sc_stateid);
        seq_printf(s, ": { type: deleg, ");

        /* Kinda dead code as long as we only support read delegs: */
        seq_printf(s, "access: %s, ",
                ds->dl_type == NFS4_OPEN_DELEGATE_READ ? "r" : "w");

        /* XXX: lease time, whether it's being recalled. */

        nfs4_show_superblock(s, file);
        seq_printf(s, ", ");
        nfs4_show_fname(s, file);
        seq_printf(s, " }\n");
        nfsd_file_put(file);

        return 0;
}

static int nfs4_show_layout(struct seq_file *s, struct nfs4_stid *st)
{
        struct nfs4_layout_stateid *ls;
        struct nfsd_file *file;

        ls = container_of(st, struct nfs4_layout_stateid, ls_stid);
        file = ls->ls_file;

        seq_printf(s, "- ");
        nfs4_show_stateid(s, &st->sc_stateid);
        seq_printf(s, ": { type: layout, ");

        /* XXX: What else would be useful? */

        nfs4_show_superblock(s, file);
        seq_printf(s, ", ");
        nfs4_show_fname(s, file);
        seq_printf(s, " }\n");

        return 0;
}

static int states_show(struct seq_file *s, void *v)
{
        struct nfs4_stid *st = v;

        switch (st->sc_type) {
        case NFS4_OPEN_STID:
                return nfs4_show_open(s, st);
        case NFS4_LOCK_STID:
                return nfs4_show_lock(s, st);
        case NFS4_DELEG_STID:
                return nfs4_show_deleg(s, st);
        case NFS4_LAYOUT_STID:
                return nfs4_show_layout(s, st);
        default:
                return 0; /* XXX: or SEQ_SKIP? */
        }
        /* XXX: copy stateids? */
}

static struct seq_operations states_seq_ops = {
        .start = states_start,
        .next = states_next,
        .stop = states_stop,
        .show = states_show
};

static int client_states_open(struct inode *inode, struct file *file)
{
        struct seq_file *s;
        struct nfs4_client *clp;
        int ret;

        clp = get_nfsdfs_clp(inode);
        if (!clp)
                return -ENXIO;

        ret = seq_open(file, &states_seq_ops);
        if (ret)
                return ret;
        s = file->private_data;
        s->private = clp;
        return 0;
}

static int client_opens_release(struct inode *inode, struct file *file)
{
        struct seq_file *m = file->private_data;
        struct nfs4_client *clp = m->private;

        /* XXX: alternatively, we could get/drop in seq start/stop */
        drop_client(clp);
        return 0;
}

static const struct file_operations client_states_fops = {
        .open           = client_states_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = client_opens_release,
};

/*
 * Normally we refuse to destroy clients that are in use, but here the
 * administrator is telling us to just do it.  We also want to wait
 * so the caller has a guarantee that the client's locks are gone by
 * the time the write returns:
 */
static void force_expire_client(struct nfs4_client *clp)
{
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
        bool already_expired;

        spin_lock(&clp->cl_lock);
        clp->cl_time = 0;
        spin_unlock(&clp->cl_lock);

        wait_event(expiry_wq, atomic_read(&clp->cl_rpc_users) == 0);
        spin_lock(&nn->client_lock);
        already_expired = list_empty(&clp->cl_lru);
        if (!already_expired)
                unhash_client_locked(clp);
        spin_unlock(&nn->client_lock);

        if (!already_expired)
                expire_client(clp);
        else
                wait_event(expiry_wq, clp->cl_nfsd_dentry == NULL);
}

static ssize_t client_ctl_write(struct file *file, const char __user *buf,
                                   size_t size, loff_t *pos)
{
        char *data;
        struct nfs4_client *clp;

        data = simple_transaction_get(file, buf, size);
        if (IS_ERR(data))
                return PTR_ERR(data);
        if (size != 7 || 0 != memcmp(data, "expire\n", 7))
                return -EINVAL;
        clp = get_nfsdfs_clp(file_inode(file));
        if (!clp)
                return -ENXIO;
        force_expire_client(clp);
        drop_client(clp);
        return 7;
}

static const struct file_operations client_ctl_fops = {
        .write          = client_ctl_write,
        .release        = simple_transaction_release,
};

static const struct tree_descr client_files[] = {
        [0] = {"info", &client_info_fops, S_IRUSR},
        [1] = {"states", &client_states_fops, S_IRUSR},
        [2] = {"ctl", &client_ctl_fops, S_IWUSR},
        [3] = {""},
};

static struct nfs4_client *create_client(struct xdr_netobj name,
                struct svc_rqst *rqstp, nfs4_verifier *verf)
{
        struct nfs4_client *clp;
        struct sockaddr *sa = svc_addr(rqstp);
        int ret;
        struct net *net = SVC_NET(rqstp);
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        clp = alloc_client(name);
        if (clp == NULL)
                return NULL;

        ret = copy_cred(&clp->cl_cred, &rqstp->rq_cred);
        if (ret) {
                free_client(clp);
                return NULL;
        }
        gen_clid(clp, nn);
        kref_init(&clp->cl_nfsdfs.cl_ref);
        nfsd4_init_cb(&clp->cl_cb_null, clp, NULL, NFSPROC4_CLNT_CB_NULL);
        clp->cl_time = ktime_get_boottime_seconds();
        clear_bit(0, &clp->cl_cb_slot_busy);
        copy_verf(clp, verf);
        memcpy(&clp->cl_addr, sa, sizeof(struct sockaddr_storage));
        clp->cl_cb_session = NULL;
        clp->net = net;
        clp->cl_nfsd_dentry = nfsd_client_mkdir(nn, &clp->cl_nfsdfs,
                        clp->cl_clientid.cl_id - nn->clientid_base,
                        client_files);
        if (!clp->cl_nfsd_dentry) {
                free_client(clp);
                return NULL;
        }
        return clp;
}

static void
add_clp_to_name_tree(struct nfs4_client *new_clp, struct rb_root *root)
{
        struct rb_node **new = &(root->rb_node), *parent = NULL;
        struct nfs4_client *clp;

        while (*new) {
                clp = rb_entry(*new, struct nfs4_client, cl_namenode);
                parent = *new;

                if (compare_blob(&clp->cl_name, &new_clp->cl_name) > 0)
                        new = &((*new)->rb_left);
                else
                        new = &((*new)->rb_right);
        }

        rb_link_node(&new_clp->cl_namenode, parent, new);
        rb_insert_color(&new_clp->cl_namenode, root);
}

static struct nfs4_client *
find_clp_in_name_tree(struct xdr_netobj *name, struct rb_root *root)
{
        int cmp;
        struct rb_node *node = root->rb_node;
        struct nfs4_client *clp;

        while (node) {
                clp = rb_entry(node, struct nfs4_client, cl_namenode);
                cmp = compare_blob(&clp->cl_name, name);
                if (cmp > 0)
                        node = node->rb_left;
                else if (cmp < 0)
                        node = node->rb_right;
                else
                        return clp;
        }
        return NULL;
}

static void
add_to_unconfirmed(struct nfs4_client *clp)
{
        unsigned int idhashval;
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

        lockdep_assert_held(&nn->client_lock);

        clear_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags);
        add_clp_to_name_tree(clp, &nn->unconf_name_tree);
        idhashval = clientid_hashval(clp->cl_clientid.cl_id);
        list_add(&clp->cl_idhash, &nn->unconf_id_hashtbl[idhashval]);
        renew_client_locked(clp);
}

static void
move_to_confirmed(struct nfs4_client *clp)
{
        unsigned int idhashval = clientid_hashval(clp->cl_clientid.cl_id);
        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

        lockdep_assert_held(&nn->client_lock);

        dprintk("NFSD: move_to_confirm nfs4_client %p\n", clp);
        list_move(&clp->cl_idhash, &nn->conf_id_hashtbl[idhashval]);
        rb_erase(&clp->cl_namenode, &nn->unconf_name_tree);
        add_clp_to_name_tree(clp, &nn->conf_name_tree);
        set_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags);
        renew_client_locked(clp);
}

static struct nfs4_client *
find_client_in_id_table(struct list_head *tbl, clientid_t *clid, bool sessions)
{
        struct nfs4_client *clp;
        unsigned int idhashval = clientid_hashval(clid->cl_id);

        list_for_each_entry(clp, &tbl[idhashval], cl_idhash) {
                if (same_clid(&clp->cl_clientid, clid)) {
                        if ((bool)clp->cl_minorversion != sessions)
                                return NULL;
                        renew_client_locked(clp);
                        return clp;
                }
        }
        return NULL;
}

static struct nfs4_client *
find_confirmed_client(clientid_t *clid, bool sessions, struct nfsd_net *nn)
{
        struct list_head *tbl = nn->conf_id_hashtbl;

        lockdep_assert_held(&nn->client_lock);
        return find_client_in_id_table(tbl, clid, sessions);
}

static struct nfs4_client *
find_unconfirmed_client(clientid_t *clid, bool sessions, struct nfsd_net *nn)
{
        struct list_head *tbl = nn->unconf_id_hashtbl;

        lockdep_assert_held(&nn->client_lock);
        return find_client_in_id_table(tbl, clid, sessions);
}

static bool clp_used_exchangeid(struct nfs4_client *clp)
{
        return clp->cl_exchange_flags != 0;
} 

static struct nfs4_client *
find_confirmed_client_by_name(struct xdr_netobj *name, struct nfsd_net *nn)
{
        lockdep_assert_held(&nn->client_lock);
        return find_clp_in_name_tree(name, &nn->conf_name_tree);
}

static struct nfs4_client *
find_unconfirmed_client_by_name(struct xdr_netobj *name, struct nfsd_net *nn)
{
        lockdep_assert_held(&nn->client_lock);
        return find_clp_in_name_tree(name, &nn->unconf_name_tree);
}

static void
gen_callback(struct nfs4_client *clp, struct nfsd4_setclientid *se, struct svc_rqst *rqstp)
{
        struct nfs4_cb_conn *conn = &clp->cl_cb_conn;
        struct sockaddr *sa = svc_addr(rqstp);
        u32 scopeid = rpc_get_scope_id(sa);
        unsigned short expected_family;

        /* Currently, we only support tcp and tcp6 for the callback channel */
        if (se->se_callback_netid_len == 3 &&
            !memcmp(se->se_callback_netid_val, "tcp", 3))
                expected_family = AF_INET;
        else if (se->se_callback_netid_len == 4 &&
                 !memcmp(se->se_callback_netid_val, "tcp6", 4))
                expected_family = AF_INET6;
        else
                goto out_err;

        conn->cb_addrlen = rpc_uaddr2sockaddr(clp->net, se->se_callback_addr_val,
                                            se->se_callback_addr_len,
                                            (struct sockaddr *)&conn->cb_addr,
                                            sizeof(conn->cb_addr));

        if (!conn->cb_addrlen || conn->cb_addr.ss_family != expected_family)
                goto out_err;

        if (conn->cb_addr.ss_family == AF_INET6)
                ((struct sockaddr_in6 *)&conn->cb_addr)->sin6_scope_id = scopeid;

        conn->cb_prog = se->se_callback_prog;
        conn->cb_ident = se->se_callback_ident;
        memcpy(&conn->cb_saddr, &rqstp->rq_daddr, rqstp->rq_daddrlen);
        trace_nfsd_cb_args(clp, conn);
        return;
out_err:
        conn->cb_addr.ss_family = AF_UNSPEC;
        conn->cb_addrlen = 0;
        trace_nfsd_cb_nodelegs(clp);
        return;
}

/*
 * Cache a reply. nfsd4_check_resp_size() has bounded the cache size.
 */
static void
nfsd4_store_cache_entry(struct nfsd4_compoundres *resp)
{
        struct xdr_buf *buf = resp->xdr.buf;
        struct nfsd4_slot *slot = resp->cstate.slot;
        unsigned int base;

        dprintk("--> %s slot %p\n", __func__, slot);

        slot->sl_flags |= NFSD4_SLOT_INITIALIZED;
        slot->sl_opcnt = resp->opcnt;
        slot->sl_status = resp->cstate.status;
        free_svc_cred(&slot->sl_cred);
        copy_cred(&slot->sl_cred, &resp->rqstp->rq_cred);

        if (!nfsd4_cache_this(resp)) {
                slot->sl_flags &= ~NFSD4_SLOT_CACHED;
                return;
        }
        slot->sl_flags |= NFSD4_SLOT_CACHED;

        base = resp->cstate.data_offset;
        slot->sl_datalen = buf->len - base;
        if (read_bytes_from_xdr_buf(buf, base, slot->sl_data, slot->sl_datalen))
                WARN(1, "%s: sessions DRC could not cache compound\n",
                     __func__);
        return;
}

/*
 * Encode the replay sequence operation from the slot values.
 * If cachethis is FALSE encode the uncached rep error on the next
 * operation which sets resp->p and increments resp->opcnt for
 * nfs4svc_encode_compoundres.
 *
 */
static __be32
nfsd4_enc_sequence_replay(struct nfsd4_compoundargs *args,
                          struct nfsd4_compoundres *resp)
{
        struct nfsd4_op *op;
        struct nfsd4_slot *slot = resp->cstate.slot;

        /* Encode the replayed sequence operation */
        op = &args->ops[resp->opcnt - 1];
        nfsd4_encode_operation(resp, op);

        if (slot->sl_flags & NFSD4_SLOT_CACHED)
                return op->status;
        if (args->opcnt == 1) {
                /*
                 * The original operation wasn't a solo sequence--we
                 * always cache those--so this retry must not match the
                 * original:
                 */
                op->status = nfserr_seq_false_retry;
        } else {
                op = &args->ops[resp->opcnt++];
                op->status = nfserr_retry_uncached_rep;
                nfsd4_encode_operation(resp, op);
        }
        return op->status;
}

/*
 * The sequence operation is not cached because we can use the slot and
 * session values.
 */
static __be32
nfsd4_replay_cache_entry(struct nfsd4_compoundres *resp,
                         struct nfsd4_sequence *seq)
{
        struct nfsd4_slot *slot = resp->cstate.slot;
        struct xdr_stream *xdr = &resp->xdr;
        __be32 *p;
        __be32 status;

        dprintk("--> %s slot %p\n", __func__, slot);

        status = nfsd4_enc_sequence_replay(resp->rqstp->rq_argp, resp);
        if (status)
                return status;

        p = xdr_reserve_space(xdr, slot->sl_datalen);
        if (!p) {
                WARN_ON_ONCE(1);
                return nfserr_serverfault;
        }
        xdr_encode_opaque_fixed(p, slot->sl_data, slot->sl_datalen);
        xdr_commit_encode(xdr);

        resp->opcnt = slot->sl_opcnt;
        return slot->sl_status;
}

/*
 * Set the exchange_id flags returned by the server.
 */
static void