[deliverable/linux.git] / fs / nfsd / nfs4state.c

/*
*  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/hash.h>
#include "xdr4.h"
#include "xdr4cb.h"
#include "vfs.h"
#include "current_stateid.h"

#include "netns.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 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)))

/* 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);

/* 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);

/*
 * 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);

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 void free_session(struct nfsd4_session *);

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_refcount);
        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;
        }

        dprintk("renewing client (clientid %08x/%08x)\n",
                        clp->cl_clientid.cl_boot,
                        clp->cl_clientid.cl_id);
        list_move_tail(&clp->cl_lru, &nn->client_lru);
        clp->cl_time = get_seconds();
}

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

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

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_refcount))
                return;
        if (!is_client_expired(clp))
                renew_client_locked(clp);
}

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_refcount, &nn->client_lock))
                return;
        if (!is_client_expired(clp))
                renew_client_locked(clp);
        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 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)) {
                        atomic_inc(&so->so_count);
                        return openowner(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(struct nfs4_file *f)
{
        kmem_cache_free(file_slab, f);
}

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

        if (atomic_dec_and_lock(&fi->fi_ref, &state_lock)) {
                hlist_del(&fi->fi_hash);
                spin_unlock(&state_lock);
                nfsd4_free_file(fi);
        }
}

static inline void
get_nfs4_file(struct nfs4_file *fi)
{
        atomic_inc(&fi->fi_ref);
}

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

static struct file *
find_writeable_file_locked(struct nfs4_file *f)
{
        struct 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 file *
find_writeable_file(struct nfs4_file *f)
{
        struct file *ret;

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

        return ret;
}

static struct file *find_readable_file_locked(struct nfs4_file *f)
{
        struct 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 file *
find_readable_file(struct nfs4_file *f)
{
        struct file *ret;

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

        return ret;
}

static struct file *
find_any_file(struct nfs4_file *f)
{
        struct file *ret;

        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 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 bool nfsd_fh_match(struct knfsd_fh *fh1, struct knfsd_fh *fh2)
{
        return fh1->fh_size == fh2->fh_size &&
                !memcmp(fh1->fh_base.fh_pad,
                                fh2->fh_base.fh_pad,
                                fh1->fh_size);
}

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 file *f1 = NULL;
                struct 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)
                        fput(f1);
                if (f2)
                        fput(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);
}

static struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl,
                                         struct kmem_cache *slab)
{
        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);
        new_id = idr_alloc_cyclic(&cl->cl_stateids, stid, 0, 0, GFP_NOWAIT);
        spin_unlock(&cl->cl_lock);
        idr_preload_end();
        if (new_id < 0)
                goto out_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: */
        atomic_set(&stid->sc_count, 1);

        /*
         * 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;
}

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

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

        stp = openlockstateid(stid);
        stp->st_stid.sc_free = nfs4_free_ol_stateid;
        return stp;
}

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;
        time_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 (seconds_since_boot() - bd->swap_time > 30) {
                spin_lock(&blocked_delegations_lock);
                if (seconds_since_boot() - 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 = seconds_since_boot();
                }
                spin_unlock(&blocked_delegations_lock);
        }
        hash = arch_fast_hash(&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 = arch_fast_hash(&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 = seconds_since_boot();
        bd->entries += 1;
        spin_unlock(&blocked_delegations_lock);
}

static struct nfs4_delegation *
alloc_init_deleg(struct nfs4_client *clp, struct svc_fh *current_fh)
{
        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));
        if (dp == NULL)
                goto out_dec;

        dp->dl_stid.sc_free = nfs4_free_deleg;
        /*
         * 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_type = NFS4_OPEN_DELEGATE_READ;
        INIT_WORK(&dp->dl_recall.cb_work, nfsd4_run_cb_recall);
        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 (!atomic_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);
        spin_unlock(&clp->cl_lock);
        s->sc_free(s);
        if (fp)
                put_nfs4_file(fp);
}

static void nfs4_put_deleg_lease(struct nfs4_file *fp)
{
        struct file *filp = NULL;
        struct file_lock *fl;

        spin_lock(&fp->fi_lock);
        if (fp->fi_lease && atomic_dec_and_test(&fp->fi_delegees)) {
                swap(filp, fp->fi_deleg_file);
                fl = fp->fi_lease;
                fp->fi_lease = NULL;
        }
        spin_unlock(&fp->fi_lock);

        if (filp) {
                vfs_setlease(filp, F_UNLCK, &fl);
                fput(filp);
        }
}

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

static void
hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp)
{
        lockdep_assert_held(&state_lock);
        lockdep_assert_held(&fp->fi_lock);

        atomic_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, &dp->dl_stid.sc_client->cl_delegations);
}

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

        lockdep_assert_held(&state_lock);

        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);
}

static void destroy_delegation(struct nfs4_delegation *dp)
{
        spin_lock(&state_lock);
        unhash_delegation_locked(dp);
        spin_unlock(&state_lock);
        nfs4_put_deleg_lease(dp->dl_stid.sc_file);
        nfs4_put_stid(&dp->dl_stid);
}

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));

        nfs4_put_deleg_lease(dp->dl_stid.sc_file);

        if (clp->cl_minorversion == 0)
                nfs4_put_stid(&dp->dl_stid);
        else {
                dp->dl_stid.sc_type = NFS4_REVOKED_DELEG_STID;
                spin_lock(&clp->cl_lock);
                list_add(&dp->dl_recall_lru, &clp->cl_revoked);
                spin_unlock(&clp->cl_lock);
        }
}

/* 
 * SETCLIENTID state 
 */

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

static unsigned int clientstr_hashval(const char *name)
{
        return opaque_hashval(name, 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 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);
        kfree(sop->so_owner.data);
        sop->so_ops->so_free(sop);
}

static void 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);

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

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

        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 file *file;

        file = find_any_file(stp->st_stid.sc_file);
        if (file)
                filp_close(file, (fl_owner_t)lo);
        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 (!atomic_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 void unhash_lock_stateid(struct nfs4_ol_stateid *stp)
{
        struct nfs4_openowner *oo = openowner(stp->st_openstp->st_stateowner);

        lockdep_assert_held(&oo->oo_owner.so_client->cl_lock);

        list_del_init(&stp->st_locks);
        unhash_ol_stateid(stp);
        unhash_stid(&stp->st_stid);
}

static void release_lock_stateid(struct nfs4_ol_stateid *stp)
{
        struct nfs4_openowner *oo = openowner(stp->st_openstp->st_stateowner);

        spin_lock(&oo->oo_owner.so_client->cl_lock);
        unhash_lock_stateid(stp);
        spin_unlock(&oo->oo_owner.so_client->cl_lock);
        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_lockowner(struct nfs4_lockowner *lo)
{
        struct nfs4_client *clp = lo->lo_owner.so_client;
        struct nfs4_ol_stateid *stp;
        struct list_head reaplist;

        INIT_LIST_HEAD(&reaplist);

        spin_lock(&clp->cl_lock);
        unhash_lockowner_locked(lo);
        while (!list_empty(&lo->lo_owner.so_stateids)) {
                stp = list_first_entry(&lo->lo_owner.so_stateids,
                                struct nfs4_ol_stateid, st_perstateowner);
                unhash_lock_stateid(stp);
                put_ol_stateid_locked(stp, &reaplist);
        }
        spin_unlock(&clp->cl_lock);
        free_ol_stateid_reaplist(&reaplist);
        nfs4_put_stateowner(&lo->lo_owner);
}

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

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

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

        unhash_ol_stateid(stp);
        release_open_stateid_locks(stp, reaplist);
}

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

        spin_lock(&stp->st_stid.sc_client->cl_lock);
        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);
                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 NFSD_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++)
                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)
{
        u32 slotsize = slot_bytes(ca);
        u32 num = ca->maxreqs;
        int avail;

        spin_lock(&nfsd_drc_lock);
        avail = min((unsigned long)NFSD_MAX_MEM_PER_SESSION,
                    nfsd_drc_max_mem - nfsd_drc_mem_used);
        num = min_t(int, num, avail / slotsize);
        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);

        if (cses->flags & SESSION4_BACK_CHAN) {
                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)
{
        if (clid->cl_boot == nn->boot_time)
                return 0;
        dprintk("NFSD stale clientid (%08x/%08x) boot_time %08lx\n",
                clid->cl_boot, clid->cl_id, nn->boot_time);
        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 = kzalloc(sizeof(struct nfs4_client), GFP_KERNEL);
        if (clp == NULL)
                return NULL;
        clp->cl_name.data = kmemdup(name.data, name.len, GFP_KERNEL);
        if (clp->cl_name.data == NULL)
                goto err_no_name;
        clp->cl_ownerstr_hashtbl = kmalloc(sizeof(struct list_head) *
                        OWNER_HASH_SIZE, 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]);
        clp->cl_name.len = name.len;
        INIT_LIST_HEAD(&clp->cl_sessions);
        idr_init(&clp->cl_stateids);
        atomic_set(&clp->cl_refcount, 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_callbacks);
        INIT_LIST_HEAD(&clp->cl_revoked);
        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:
        kfree(clp);
        return NULL;
}

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);
        free_svc_cred(&clp->cl_cred);
        kfree(clp->cl_ownerstr_hashtbl);
        kfree(clp->cl_name.data);
        idr_destroy(&clp->cl_stateids);
        kfree(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_refcount))
                return nfserr_jukebox;
        unhash_client_locked(clp);
        return nfs_ok;
}

static void
__destroy_client(struct nfs4_client *clp)
{
        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);
                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);
                nfs4_put_deleg_lease(dp->dl_stid.sc_file);
                nfs4_put_stid(&dp->dl_stid);
        }
        while (!list_empty(&clp->cl_revoked)) {
                dp = list_entry(reaplist.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);
                atomic_inc(&oo->oo_owner.so_count);
                release_openowner(oo);
        }
        nfsd4_shutdown_callback(clp);
        if (clp->cl_cb_conn.cb_xprt)
                svc_xprt_put(clp->cl_cb_conn.cb_xprt);
        free_client(clp);
}

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

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)
{
        if (source->cr_principal) {
                target->cr_principal =
                                kstrdup(source->cr_principal, GFP_KERNEL);
                if (target->cr_principal == NULL)
                        return -ENOMEM;
        } else
                target->cr_principal = NULL;
        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 long long
compare_blob(const struct xdr_netobj *o1, const struct xdr_netobj *o2)
{
        long long res;

        res = o1->len - o2->len;
        if (res)
                return res;
        return (long long)memcmp(o1->data, o2->data, o1->len);
}

static int same_name(const char *n1, const char *n2)
{
        return 0 == memcmp(n1, n2, HEXDIR_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(GROUP_AT(g1, i), GROUP_AT(g2, 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;
        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;
}

static bool 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 (!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)get_seconds();
        verf[1] = (__force __be32)nn->clientid_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 = 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)
                        atomic_inc(&s->sc_count);
                else
                        s = NULL;
        }
        spin_unlock(&cl->cl_lock);
        return s;
}

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);

        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;
        }
        INIT_WORK(&clp->cl_cb_null.cb_work, nfsd4_run_cb_null);
        clp->cl_time = get_seconds();
        clear_bit(0, &clp->cl_cb_slot_busy);
        copy_verf(clp, verf);
        rpc_copy_addr((struct sockaddr *) &clp->cl_addr, sa);
        clp->cl_cb_session = NULL;
        clp->net = net;
        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)
{
        long long 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);
        return;
out_err:
        conn->cb_addr.ss_family = AF_UNSPEC;
        conn->cb_addrlen = 0;
        dprintk(KERN_INFO "NFSD: this client (clientid %08x/%08x) "
                "will not receive delegations\n",
                clp->cl_clientid.cl_boot, clp->cl_clientid.cl_id);

        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_opcnt = resp->opcnt;
        slot->sl_status = resp->cstate.status;

        slot->sl_flags |= NFSD4_SLOT_INITIALIZED;
        if (nfsd4_not_cached(resp)) {
                slot->sl_datalen = 0;
                return;
        }
        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("%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);

        /* Return nfserr_retry_uncached_rep in next operation. */
        if (args->opcnt > 1 && !(slot->sl_flags & NFSD4_SLOT_CACHETHIS)) {
                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
nfsd4_set_ex_flags(struct nfs4_client *new, struct nfsd4_exchange_id *clid)
{
        /* pNFS is not supported */
        new->cl_exchange_flags |= EXCHGID4_FLAG_USE_NON_PNFS;

        /* Referrals are supported, Migration is not. */
        new->cl_exchange_flags |= EXCHGID4_FLAG_SUPP_MOVED_REFER;

        /* set the wire flags to return to client. */
        clid->flags = new->cl_exchange_flags;
}

static bool client_has_state(struct nfs4_client *clp)
{
        /*
         * Note clp->cl_openowners check isn't quite right: there's no
         * need to count owners without stateid's.
         *
         * Also note we should probably be using this in 4.0 case too.
         */
        return !list_empty(&clp->cl_openowners)
                || !list_empty(&clp->cl_delegations)
                || !list_empty(&clp->cl_sessions);
}

__be32
nfsd4_exchange_id(struct svc_rqst *rqstp,
                  struct nfsd4_compound_state *cstate,
                  struct nfsd4_exchange_id *exid)
{
        struct nfs4_client *conf, *new;
        struct nfs4_client *unconf = NULL;
        __be32 status;
        char                    addr_str[INET6_ADDRSTRLEN];
        nfs4_verifier           verf = exid->verifier;
        struct sockaddr         *sa = svc_addr(rqstp);
        bool    update = exid->flags & EXCHGID4_FLAG_UPD_CONFIRMED_REC_A;
        struct nfsd_net         *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        rpc_ntop(sa, addr_str, sizeof(addr_str));
        dprintk("%s rqstp=%p exid=%p clname.len=%u clname.data=%p "
                "ip_addr=%s flags %x, spa_how %d\n",
                __func__, rqstp, exid, exid->clname.len, exid->clname.data,
                addr_str, exid->flags, exid->spa_how);

        if (exid->flags & ~EXCHGID4_FLAG_MASK_A)
                return nfserr_inval;

        switch (exid->spa_how) {
        case SP4_MACH_CRED:
                if (!svc_rqst_integrity_protected(rqstp))
                        return nfserr_inval;
        case SP4_NONE:
                break;
        default:                                /* checked by xdr code */
                WARN_ON_ONCE(1);
        case SP4_SSV:
                return nfserr_encr_alg_unsupp;
        }

        new = create_client(exid->clname, rqstp, &verf);
        if (new == NULL)
                return nfserr_jukebox;

        /* Cases below refer to rfc 5661 section 18.35.4: */
        spin_lock(&nn->client_lock);
        conf = find_confirmed_client_by_name(&exid->clname, nn);
        if (conf) {
                bool creds_match = same_creds(&conf->cl_cred, &rqstp->rq_cred);
                bool verfs_match = same_verf(&verf, &conf->cl_verifier);

                if (update) {
                        if (!clp_used_exchangeid(conf)) { /* buggy client */
                                status = nfserr_inval;
                                goto out;
                        }
                        if (!mach_creds_match(conf, rqstp)) {
                                status = nfserr_wrong_cred;
                                goto out;
                        }
                        if (!creds_match) { /* case 9 */
                                status = nfserr_perm;
                                goto out;
                        }
                        if (!verfs_match) { /* case 8 */
                                status = nfserr_not_same;
                                goto out;
                        }
                        /* case 6 */
                        exid->flags |= EXCHGID4_FLAG_CONFIRMED_R;
                        goto out_copy;
                }
                if (!creds_match) { /* case 3 */
                        if (client_has_state(conf)) {
                                status = nfserr_clid_inuse;
                                goto out;
                        }
                        goto out_new;
                }
                if (verfs_match) { /* case 2 */
                        conf->cl_exchange_flags |= EXCHGID4_FLAG_CONFIRMED_R;
                        goto out_copy;
                }
                /* case 5, client reboot */
                conf = NULL;
                goto out_new;
        }

        if (update) { /* case 7 */
                status = nfserr_noent;
                goto out;
        }

        unconf  = find_unconfirmed_client_by_name(&exid->clname, nn);
        if (unconf) /* case 4, possible retry or client restart */
                unhash_client_locked(unconf);

        /* case 1 (normal case) */
out_new:
        if (conf) {
                status = mark_client_expired_locked(conf);
                if (status)
                        goto out;
        }
        new->cl_minorversion = cstate->minorversion;
        new->cl_mach_cred = (exid->spa_how == SP4_MACH_CRED);

        gen_clid(new, nn);
        add_to_unconfirmed(new);
        swap(new, conf);
out_copy:
        exid->clientid.cl_boot = conf->cl_clientid.cl_boot;
        exid->clientid.cl_id = conf->cl_clientid.cl_id;

        exid->seqid = conf->cl_cs_slot.sl_seqid + 1;
        nfsd4_set_ex_flags(conf, exid);

        dprintk("nfsd4_exchange_id seqid %d flags %x\n",
                conf->cl_cs_slot.sl_seqid, conf->cl_exchange_flags);
        status = nfs_ok;

out:
        spin_unlock(&nn->client_lock);
        if (new)
                expire_client(new);
        if (unconf)
                expire_client(unconf);
        return status;
}

static __be32
check_slot_seqid(u32 seqid, u32 slot_seqid, int slot_inuse)
{
        dprintk("%s enter. seqid %d slot_seqid %d\n", __func__, seqid,
                slot_seqid);

        /* The slot is in use, and no response has been sent. */
        if (slot_inuse) {
                if (seqid == slot_seqid)
                        return nfserr_jukebox;
                else
                        return nfserr_seq_misordered;
        }
        /* Note unsigned 32-bit arithmetic handles wraparound: */
        if (likely(seqid == slot_seqid + 1))
                return nfs_ok;
        if (seqid == slot_seqid)
                return nfserr_replay_cache;
        return nfserr_seq_misordered;
}

/*
 * Cache the create session result into the create session single DRC
 * slot cache by saving the xdr structure. sl_seqid has been set.
 * Do this for solo or embedded create session operations.
 */
static void
nfsd4_cache_create_session(struct nfsd4_create_session *cr_ses,
                           struct nfsd4_clid_slot *slot, __be32 nfserr)
{
        slot->sl_status = nfserr;
        memcpy(&slot->sl_cr_ses, cr_ses, sizeof(*cr_ses));
}

static __be32
nfsd4_replay_create_session(struct nfsd4_create_session *cr_ses,
                            struct nfsd4_clid_slot *slot)
{
        memcpy(cr_ses, &slot->sl_cr_ses, sizeof(*cr_ses));
        return slot->sl_status;
}

#define NFSD_MIN_REQ_HDR_SEQ_SZ ((\
                        2 * 2 + /* credential,verifier: AUTH_NULL, length 0 */ \
                        1 +     /* MIN tag is length with zero, only length */ \
                        3 +     /* version, opcount, opcode */ \
                        XDR_QUADLEN(NFS4_MAX_SESSIONID_LEN) + \
                                /* seqid, slotID, slotID, cache */ \
                        4 ) * sizeof(__be32))

#define NFSD_MIN_RESP_HDR_SEQ_SZ ((\
                        2 +     /* verifier: AUTH_NULL, length 0 */\
                        1 +     /* status */ \
                        1 +     /* MIN tag is length with zero, only length */ \
                        3 +     /* opcount, opcode, opstatus*/ \
                        XDR_QUADLEN(NFS4_MAX_SESSIONID_LEN) + \
                                /* seqid, slotID, slotID, slotID, status */ \
                        5 ) * sizeof(__be32))

static __be32 check_forechannel_attrs(struct nfsd4_channel_attrs *ca, struct nfsd_net *nn)
{
        u32 maxrpc = nn->nfsd_serv->sv_max_mesg;

        if (ca->maxreq_sz < NFSD_MIN_REQ_HDR_SEQ_SZ)
                return nfserr_toosmall;
        if (ca->maxresp_sz < NFSD_MIN_RESP_HDR_SEQ_SZ)
                return nfserr_toosmall;
        ca->headerpadsz = 0;
        ca->maxreq_sz = min_t(u32, ca->maxreq_sz, maxrpc);
        ca->maxresp_sz = min_t(u32, ca->maxresp_sz, maxrpc);
        ca->maxops = min_t(u32, ca->maxops, NFSD_MAX_OPS_PER_COMPOUND);
        ca->maxresp_cached = min_t(u32, ca->maxresp_cached,
                        NFSD_SLOT_CACHE_SIZE + NFSD_MIN_HDR_SEQ_SZ);
        ca->maxreqs = min_t(u32, ca->maxreqs, NFSD_MAX_SLOTS_PER_SESSION);
        /*
         * Note decreasing slot size below client's request may make it
         * difficult for client to function correctly, whereas
         * decreasing the number of slots will (just?) affect
         * performance.  When short on memory we therefore prefer to
         * decrease number of slots instead of their size.  Clients that
         * request larger slots than they need will get poor results:
         */
        ca->maxreqs = nfsd4_get_drc_mem(ca);
        if (!ca->maxreqs)
                return nfserr_jukebox;

        return nfs_ok;
}

#define NFSD_CB_MAX_REQ_SZ      ((NFS4_enc_cb_recall_sz + \
                                 RPC_MAX_HEADER_WITH_AUTH) * sizeof(__be32))
#define NFSD_CB_MAX_RESP_SZ     ((NFS4_dec_cb_recall_sz + \
                                 RPC_MAX_REPHEADER_WITH_AUTH) * sizeof(__be32))

static __be32 check_backchannel_attrs(struct nfsd4_channel_attrs *ca)
{
        ca->headerpadsz = 0;

        /*
         * These RPC_MAX_HEADER macros are overkill, especially since we
         * don't even do gss on the backchannel yet.  But this is still
         * less than 1k.  Tighten up this estimate in the unlikely event
         * it turns out to be a problem for some client:
         */
        if (ca->maxreq_sz < NFSD_CB_MAX_REQ_SZ)
                return nfserr_toosmall;
        if (ca->maxresp_sz < NFSD_CB_MAX_RESP_SZ)
                return nfserr_toosmall;
        ca->maxresp_cached = 0;
        if (ca->maxops < 2)
                return nfserr_toosmall;

        return nfs_ok;
}

static __be32 nfsd4_check_cb_sec(struct nfsd4_cb_sec *cbs)
{
        switch (cbs->flavor) {
        case RPC_AUTH_NULL:
        case RPC_AUTH_UNIX:
                return nfs_ok;
        default:
                /*
                 * GSS case: the spec doesn't allow us to return this
                 * error.  But it also doesn't allow us not to support
                 * GSS.
                 * I'd rather this fail hard than return some error the
                 * client might think it can already handle:
                 */
                return nfserr_encr_alg_unsupp;
        }
}

__be32
nfsd4_create_session(struct svc_rqst *rqstp,
                     struct nfsd4_compound_state *cstate,
                     struct nfsd4_create_session *cr_ses)
{
        struct sockaddr *sa = svc_addr(rqstp);
        struct nfs4_client *conf, *unconf;
        struct nfs4_client *old = NULL;
        struct nfsd4_session *new;
        struct nfsd4_conn *conn;
        struct nfsd4_clid_slot *cs_slot = NULL;
        __be32 status = 0;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        if (cr_ses->flags & ~SESSION4_FLAG_MASK_A)
                return nfserr_inval;
        status = nfsd4_check_cb_sec(&cr_ses->cb_sec);
        if (status)
                return status;
        status = check_forechannel_attrs(&cr_ses->fore_channel, nn);
        if (status)
                return status;
        status = check_backchannel_attrs(&cr_ses->back_channel);
        if (status)
                goto out_release_drc_mem;
        status = nfserr_jukebox;
        new = alloc_session(&cr_ses->fore_channel, &cr_ses->back_channel);
        if (!new)
                goto out_release_drc_mem;
        conn = alloc_conn_from_crses(rqstp, cr_ses);
        if (!conn)
                goto out_free_session;

        spin_lock(&nn->client_lock);
        unconf = find_unconfirmed_client(&cr_ses->clientid, true, nn);
        conf = find_confirmed_client(&cr_ses->clientid, true, nn);
        WARN_ON_ONCE(conf && unconf);

        if (conf) {
                status = nfserr_wrong_cred;
                if (!mach_creds_match(conf, rqstp))
                        goto out_free_conn;
                cs_slot = &conf->cl_cs_slot;
                status = check_slot_seqid(cr_ses->seqid, cs_slot->sl_seqid, 0);
                if (status == nfserr_replay_cache) {
                        status = nfsd4_replay_create_session(cr_ses, cs_slot);
                        goto out_free_conn;
                } else if (cr_ses->seqid != cs_slot->sl_seqid + 1) {
                        status = nfserr_seq_misordered;
                        goto out_free_conn;
                }
        } else if (unconf) {
                if (!same_creds(&unconf->cl_cred, &rqstp->rq_cred) ||
                    !rpc_cmp_addr(sa, (struct sockaddr *) &unconf->cl_addr)) {
                        status = nfserr_clid_inuse;
                        goto out_free_conn;
                }
                status = nfserr_wrong_cred;
                if (!mach_creds_match(unconf, rqstp))
                        goto out_free_conn;
                cs_slot = &unconf->cl_cs_slot;
                status = check_slot_seqid(cr_ses->seqid, cs_slot->sl_seqid, 0);
                if (status) {
                        /* an unconfirmed replay returns misordered */
                        status = nfserr_seq_misordered;
                        goto out_free_conn;
                }
                old = find_confirmed_client_by_name(&unconf->cl_name, nn);
                if (old) {
                        status = mark_client_expired_locked(old);
                        if (status) {
                                old = NULL;
                                goto out_free_conn;
                        }
                }
                move_to_confirmed(unconf);
                conf = unconf;
        } else {
                status = nfserr_stale_clientid;
                goto out_free_conn;
        }
        status = nfs_ok;
        /*
         * We do not support RDMA or persistent sessions
         */
        cr_ses->flags &= ~SESSION4_PERSIST;
        cr_ses->flags &= ~SESSION4_RDMA;

        init_session(rqstp, new, conf, cr_ses);
        nfsd4_get_session_locked(new);

        memcpy(cr_ses->sessionid.data, new->se_sessionid.data,
               NFS4_MAX_SESSIONID_LEN);
        cs_slot->sl_seqid++;
        cr_ses->seqid = cs_slot->sl_seqid;

        /* cache solo and embedded create sessions under the client_lock */
        nfsd4_cache_create_session(cr_ses, cs_slot, status);
        spin_unlock(&nn->client_lock);
        /* init connection and backchannel */
        nfsd4_init_conn(rqstp, conn, new);
        nfsd4_put_session(new);
        if (old)
                expire_client(old);
        return status;
out_free_conn:
        spin_unlock(&nn->client_lock);
        free_conn(conn);
        if (old)
                expire_client(old);
out_free_session:
        __free_session(new);
out_release_drc_mem:
        nfsd4_put_drc_mem(&cr_ses->fore_channel);
        return status;
}

static __be32 nfsd4_map_bcts_dir(u32 *dir)
{
        switch (*dir) {
        case NFS4_CDFC4_FORE:
        case NFS4_CDFC4_BACK:
                return nfs_ok;
        case NFS4_CDFC4_FORE_OR_BOTH:
        case NFS4_CDFC4_BACK_OR_BOTH:
                *dir = NFS4_CDFC4_BOTH;
                return nfs_ok;
        };
        return nfserr_inval;
}

__be32 nfsd4_backchannel_ctl(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, struct nfsd4_backchannel_ctl *bc)
{
        struct nfsd4_session *session = cstate->session;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
        __be32 status;

        status = nfsd4_check_cb_sec(&bc->bc_cb_sec);
        if (status)
                return status;
        spin_lock(&nn->client_lock);
        session->se_cb_prog = bc->bc_cb_program;
        session->se_cb_sec = bc->bc_cb_sec;
        spin_unlock(&nn->client_lock);

        nfsd4_probe_callback(session->se_client);

        return nfs_ok;
}

__be32 nfsd4_bind_conn_to_session(struct svc_rqst *rqstp,
                     struct nfsd4_compound_state *cstate,
                     struct nfsd4_bind_conn_to_session *bcts)
{
        __be32 status;
        struct nfsd4_conn *conn;
        struct nfsd4_session *session;
        struct net *net = SVC_NET(rqstp);
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        if (!nfsd4_last_compound_op(rqstp))
                return nfserr_not_only_op;
        spin_lock(&nn->client_lock);
        session = find_in_sessionid_hashtbl(&bcts->sessionid, net, &status);
        spin_unlock(&nn->client_lock);
        if (!session)
                goto out_no_session;
        status = nfserr_wrong_cred;
        if (!mach_creds_match(session->se_client, rqstp))
                goto out;
        status = nfsd4_map_bcts_dir(&bcts->dir);
        if (status)
                goto out;
        conn = alloc_conn(rqstp, bcts->dir);
        status = nfserr_jukebox;
        if (!conn)
                goto out;
        nfsd4_init_conn(rqstp, conn, session);
        status = nfs_ok;
out:
        nfsd4_put_session(session);
out_no_session:
        return status;
}

static bool nfsd4_compound_in_session(struct nfsd4_session *session, struct nfs4_sessionid *sid)
{
        if (!session)
                return 0;
        return !memcmp(sid, &session->se_sessionid, sizeof(*sid));
}

__be32
nfsd4_destroy_session(struct svc_rqst *r,
                      struct nfsd4_compound_state *cstate,
                      struct nfsd4_destroy_session *sessionid)
{
        struct nfsd4_session *ses;
        __be32 status;
        int ref_held_by_me = 0;
        struct net *net = SVC_NET(r);
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        status = nfserr_not_only_op;
        if (nfsd4_compound_in_session(cstate->session, &sessionid->sessionid)) {
                if (!nfsd4_last_compound_op(r))
                        goto out;
                ref_held_by_me++;
        }
        dump_sessionid(__func__, &sessionid->sessionid);
        spin_lock(&nn->client_lock);
        ses = find_in_sessionid_hashtbl(&sessionid->sessionid, net, &status);
        if (!ses)
                goto out_client_lock;
        status = nfserr_wrong_cred;
        if (!mach_creds_match(ses->se_client, r))
                goto out_put_session;
        status = mark_session_dead_locked(ses, 1 + ref_held_by_me);
        if (status)
                goto out_put_session;
        unhash_session(ses);
        spin_unlock(&nn->client_lock);

        nfsd4_probe_callback_sync(ses->se_client);

        spin_lock(&nn->client_lock);
        status = nfs_ok;
out_put_session:
        nfsd4_put_session_locked(ses);
out_client_lock:
        spin_unlock(&nn->client_lock);
out:
        return status;
}

static struct nfsd4_conn *__nfsd4_find_conn(struct svc_xprt *xpt, struct nfsd4_session *s)
{
        struct nfsd4_conn *c;

        list_for_each_entry(c, &s->se_conns, cn_persession) {
                if (c->cn_xprt == xpt) {
                        return c;
                }
        }
        return NULL;
}

static __be32 nfsd4_sequence_check_conn(struct nfsd4_conn *new, struct nfsd4_session *ses)
{
        struct nfs4_client *clp = ses->se_client;
        struct nfsd4_conn *c;
        __be32 status = nfs_ok;
        int ret;

        spin_lock(&clp->cl_lock);
        c = __nfsd4_find_conn(new->cn_xprt, ses);
        if (c)
                goto out_free;
        status = nfserr_conn_not_bound_to_session;
        if (clp->cl_mach_cred)
                goto out_free;
        __nfsd4_hash_conn(new, ses);
        spin_unlock(&clp->cl_lock);
        ret = nfsd4_register_conn(new);
        if (ret)
                /* oops; xprt is already down: */
                nfsd4_conn_lost(&new->cn_xpt_user);
        return nfs_ok;
out_free:
        spin_unlock(&clp->cl_lock);
        free_conn(new);
        return status;
}

static bool nfsd4_session_too_many_ops(struct svc_rqst *rqstp, struct nfsd4_session *session)
{
        struct nfsd4_compoundargs *args = rqstp->rq_argp;

        return args->opcnt > session->se_fchannel.maxops;
}

static bool nfsd4_request_too_big(struct svc_rqst *rqstp,
                                  struct nfsd4_session *session)
{
        struct xdr_buf *xb = &rqstp->rq_arg;

        return xb->len > session->se_fchannel.maxreq_sz;
}

__be32
nfsd4_sequence(struct svc_rqst *rqstp,
               struct nfsd4_compound_state *cstate,
               struct nfsd4_sequence *seq)
{
        struct nfsd4_compoundres *resp = rqstp->rq_resp;
        struct xdr_stream *xdr = &resp->xdr;
        struct nfsd4_session *session;
        struct nfs4_client *clp;
        struct nfsd4_slot *slot;
        struct nfsd4_conn *conn;
        __be32 status;
        int buflen;
        struct net *net = SVC_NET(rqstp);
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        if (resp->opcnt != 1)
                return nfserr_sequence_pos;

        /*
         * Will be either used or freed by nfsd4_sequence_check_conn
         * below.
         */
        conn = alloc_conn(rqstp, NFS4_CDFC4_FORE);
        if (!conn)
                return nfserr_jukebox;

        spin_lock(&nn->client_lock);
        session = find_in_sessionid_hashtbl(&seq->sessionid, net, &status);
        if (!session)
                goto out_no_session;
        clp = session->se_client;

        status = nfserr_too_many_ops;
        if (nfsd4_session_too_many_ops(rqstp, session))
                goto out_put_session;

        status = nfserr_req_too_big;
        if (nfsd4_request_too_big(rqstp, session))
                goto out_put_session;

        status = nfserr_badslot;
        if (seq->slotid >= session->se_fchannel.maxreqs)
                goto out_put_session;

        slot = session->se_slots[seq->slotid];
        dprintk("%s: slotid %d\n", __func__, seq->slotid);

        /* We do not negotiate the number of slots yet, so set the
         * maxslots to the session maxreqs which is used to encode
         * sr_highest_slotid and the sr_target_slot id to maxslots */
        seq->maxslots = session->se_fchannel.maxreqs;

        status = check_slot_seqid(seq->seqid, slot->sl_seqid,
                                        slot->sl_flags & NFSD4_SLOT_INUSE);
        if (status == nfserr_replay_cache) {
                status = nfserr_seq_misordered;
                if (!(slot->sl_flags & NFSD4_SLOT_INITIALIZED))
                        goto out_put_session;
                cstate->slot = slot;
                cstate->session = session;
                cstate->clp = clp;
                /* Return the cached reply status and set cstate->status
                 * for nfsd4_proc_compound processing */
                status = nfsd4_replay_cache_entry(resp, seq);
                cstate->status = nfserr_replay_cache;
                goto out;
        }
        if (status)
                goto out_put_session;

        status = nfsd4_sequence_check_conn(conn, session);
        conn = NULL;
        if (status)
                goto out_put_session;

        buflen = (seq->cachethis) ?
                        session->se_fchannel.maxresp_cached :
                        session->se_fchannel.maxresp_sz;
        status = (seq->cachethis) ? nfserr_rep_too_big_to_cache :
                                    nfserr_rep_too_big;
        if (xdr_restrict_buflen(xdr, buflen - rqstp->rq_auth_slack))
                goto out_put_session;
        svc_reserve(rqstp, buflen);

        status = nfs_ok;
        /* Success! bump slot seqid */
        slot->sl_seqid = seq->seqid;
        slot->sl_flags |= NFSD4_SLOT_INUSE;
        if (seq->cachethis)
                slot->sl_flags |= NFSD4_SLOT_CACHETHIS;
        else
                slot->sl_flags &= ~NFSD4_SLOT_CACHETHIS;

        cstate->slot = slot;
        cstate->session = session;
        cstate->clp = clp;

out:
        switch (clp->cl_cb_state) {
        case NFSD4_CB_DOWN:
                seq->status_flags = SEQ4_STATUS_CB_PATH_DOWN;
                break;
        case NFSD4_CB_FAULT:
                seq->status_flags = SEQ4_STATUS_BACKCHANNEL_FAULT;
                break;
        default:
                seq->status_flags = 0;
        }
        if (!list_empty(&clp->cl_revoked))
                seq->status_flags |= SEQ4_STATUS_RECALLABLE_STATE_REVOKED;
out_no_session:
        if (conn)
                free_conn(conn);
        spin_unlock(&nn->client_lock);
        return status;
out_put_session:
        nfsd4_put_session_locked(session);
        goto out_no_session;
}

void
nfsd4_sequence_done(struct nfsd4_compoundres *resp)
{
        struct nfsd4_compound_state *cs = &resp->cstate;

        if (nfsd4_has_session(cs)) {
                if (cs->status != nfserr_replay_cache) {
                        nfsd4_store_cache_entry(resp);
                        cs->slot->sl_flags &= ~NFSD4_SLOT_INUSE;
                }
                /* Drop session reference that was taken in nfsd4_sequence() */
                nfsd4_put_session(cs->session);
        } else if (cs->clp)
                put_client_renew(cs->clp);
}

__be32
nfsd4_destroy_clientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, struct nfsd4_destroy_clientid *dc)
{
        struct nfs4_client *conf, *unconf;
        struct nfs4_client *clp = NULL;
        __be32 status = 0;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        spin_lock(&nn->client_lock);
        unconf = find_unconfirmed_client(&dc->clientid, true, nn);
        conf = find_confirmed_client(&dc->clientid, true, nn);
        WARN_ON_ONCE(conf && unconf);

        if (conf) {
                if (client_has_state(conf)) {
                        status = nfserr_clientid_busy;
                        goto out;
                }
                status = mark_client_expired_locked(conf);
                if (status)
                        goto out;
                clp = conf;
        } else if (unconf)
                clp = unconf;
        else {
                status = nfserr_stale_clientid;
                goto out;
        }
        if (!mach_creds_match(clp, rqstp)) {
                clp = NULL;
                status = nfserr_wrong_cred;
                goto out;
        }
        unhash_client_locked(clp);
out:
        spin_unlock(&nn->client_lock);
        if (clp)
                expire_client(clp);
        return status;
}

__be32
nfsd4_reclaim_complete(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, struct nfsd4_reclaim_complete *rc)
{
        __be32 status = 0;

        if (rc->rca_one_fs) {
                if (!cstate->current_fh.fh_dentry)
                        return nfserr_nofilehandle;
                /*
                 * We don't take advantage of the rca_one_fs case.
                 * That's OK, it's optional, we can safely ignore it.
                 */
                 return nfs_ok;
        }

        status = nfserr_complete_already;
        if (test_and_set_bit(NFSD4_CLIENT_RECLAIM_COMPLETE,
                             &cstate->session->se_client->cl_flags))
                goto out;

        status = nfserr_stale_clientid;
        if (is_client_expired(cstate->session->se_client))
                /*
                 * The following error isn't really legal.
                 * But we only get here if the client just explicitly
                 * destroyed the client.  Surely it no longer cares what
                 * error it gets back on an operation for the dead
                 * client.
                 */
                goto out;

        status = nfs_ok;
        nfsd4_client_record_create(cstate->session->se_client);
out:
        return status;
}

__be32
nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                  struct nfsd4_setclientid *setclid)
{
        struct xdr_netobj       clname = setclid->se_name;
        nfs4_verifier           clverifier = setclid->se_verf;
        struct nfs4_client      *conf, *new;
        struct nfs4_client      *unconf = NULL;
        __be32                  status;
        struct nfsd_net         *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        new = create_client(clname, rqstp, &clverifier);
        if (new == NULL)
                return nfserr_jukebox;
        /* Cases below refer to rfc 3530 section 14.2.33: */
        spin_lock(&nn->client_lock);
        conf = find_confirmed_client_by_name(&clname, nn);
        if (conf) {
                /* case 0: */
                status = nfserr_clid_inuse;
                if (clp_used_exchangeid(conf))
                        goto out;
                if (!same_creds(&conf->cl_cred, &rqstp->rq_cred)) {
                        char addr_str[INET6_ADDRSTRLEN];
                        rpc_ntop((struct sockaddr *) &conf->cl_addr, addr_str,
                                 sizeof(addr_str));
                        dprintk("NFSD: setclientid: string in use by client "
                                "at %s\n", addr_str);
                        goto out;
                }
        }
        unconf = find_unconfirmed_client_by_name(&clname, nn);
        if (unconf)
                unhash_client_locked(unconf);
        if (conf && same_verf(&conf->cl_verifier, &clverifier))
                /* case 1: probable callback update */
                copy_clid(new, conf);
        else /* case 4 (new client) or cases 2, 3 (client reboot): */
                gen_clid(new, nn);
        new->cl_minorversion = 0;
        gen_callback(new, setclid, rqstp);
        add_to_unconfirmed(new);
        setclid->se_clientid.cl_boot = new->cl_clientid.cl_boot;
        setclid->se_clientid.cl_id = new->cl_clientid.cl_id;
        memcpy(setclid->se_confirm.data, new->cl_confirm.data, sizeof(setclid->se_confirm.data));
        new = NULL;
        status = nfs_ok;
out:
        spin_unlock(&nn->client_lock);
        if (new)
                free_client(new);
        if (unconf)
                expire_client(unconf);
        return status;
}


__be32
nfsd4_setclientid_confirm(struct svc_rqst *rqstp,
                         struct nfsd4_compound_state *cstate,
                         struct nfsd4_setclientid_confirm *setclientid_confirm)
{
        struct nfs4_client *conf, *unconf;
        struct nfs4_client *old = NULL;
        nfs4_verifier confirm = setclientid_confirm->sc_confirm; 
        clientid_t * clid = &setclientid_confirm->sc_clientid;
        __be32 status;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        if (STALE_CLIENTID(clid, nn))
                return nfserr_stale_clientid;

        spin_lock(&nn->client_lock);
        conf = find_confirmed_client(clid, false, nn);
        unconf = find_unconfirmed_client(clid, false, nn);
        /*
         * We try hard to give out unique clientid's, so if we get an
         * attempt to confirm the same clientid with a different cred,
         * there's a bug somewhere.  Let's charitably assume it's our
         * bug.
         */
        status = nfserr_serverfault;
        if (unconf && !same_creds(&unconf->cl_cred, &rqstp->rq_cred))
                goto out;
        if (conf && !same_creds(&conf->cl_cred, &rqstp->rq_cred))
                goto out;
        /* cases below refer to rfc 3530 section 14.2.34: */
        if (!unconf || !same_verf(&confirm, &unconf->cl_confirm)) {
                if (conf && !unconf) /* case 2: probable retransmit */
                        status = nfs_ok;
                else /* case 4: client hasn't noticed we rebooted yet? */
                        status = nfserr_stale_clientid;
                goto out;
        }
        status = nfs_ok;
        if (conf) { /* case 1: callback update */
                old = unconf;
                unhash_client_locked(old);
                nfsd4_change_callback(conf, &unconf->cl_cb_conn);
        } else { /* case 3: normal case; new or rebooted client */
                old = find_confirmed_client_by_name(&unconf->cl_name, nn);
                if (old) {
                        status = mark_client_expired_locked(old);
                        if (status) {
                                old = NULL;
                                goto out;
                        }
                }
                move_to_confirmed(unconf);
                conf = unconf;
        }
        get_client_locked(conf);
        spin_unlock(&nn->client_lock);
        nfsd4_probe_callback(conf);
        spin_lock(&nn->client_lock);
        put_client_renew_locked(conf);
out:
        spin_unlock(&nn->client_lock);
        if (old)
                expire_client(old);
        return status;
}

static struct nfs4_file *nfsd4_alloc_file(void)
{
        return kmem_cache_alloc(file_slab, GFP_KERNEL);
}

/* OPEN Share state helper functions */
static void nfsd4_init_file(struct nfs4_file *fp, struct knfsd_fh *fh)
{
        unsigned int hashval = file_hashval(fh);

        lockdep_assert_held(&state_lock);

        atomic_set(&fp->fi_ref, 1);
        spin_lock_init(&fp->fi_lock);
        INIT_LIST_HEAD(&fp->fi_stateids);
        INIT_LIST_HEAD(&fp->fi_delegations);
        fh_copy_shallow(&fp->fi_fhandle, fh);
        fp->fi_had_conflict = false;
        fp->fi_lease = NULL;
        fp->fi_share_deny = 0;
        memset(fp->fi_fds, 0, sizeof(fp->fi_fds));
        memset(fp->fi_access, 0, sizeof(fp->fi_access));
        hlist_add_head(&fp->fi_hash, &file_hashtbl[hashval]);
}

void
nfsd4_free_slabs(void)
{
        kmem_cache_destroy(openowner_slab);
        kmem_cache_destroy(lockowner_slab);
        kmem_cache_destroy(file_slab);
        kmem_cache_destroy(stateid_slab);
        kmem_cache_destroy(deleg_slab);
}

int
nfsd4_init_slabs(void)
{
        openowner_slab = kmem_cache_create("nfsd4_openowners",
                        sizeof(struct nfs4_openowner), 0, 0, NULL);
        if (openowner_slab == NULL)
                goto out;
        lockowner_slab = kmem_cache_create("nfsd4_lockowners",
                        sizeof(struct nfs4_lockowner), 0, 0, NULL);
        if (lockowner_slab == NULL)
                goto out_free_openowner_slab;
        file_slab = kmem_cache_create("nfsd4_files",
                        sizeof(struct nfs4_file), 0, 0, NULL);
        if (file_slab == NULL)
                goto out_free_lockowner_slab;
        stateid_slab = kmem_cache_create("nfsd4_stateids",
                        sizeof(struct nfs4_ol_stateid), 0, 0, NULL);
        if (stateid_slab == NULL)
                goto out_free_file_slab;
        deleg_slab = kmem_cache_create("nfsd4_delegations",
                        sizeof(struct nfs4_delegation), 0, 0, NULL);
        if (deleg_slab == NULL)
                goto out_free_stateid_slab;
        return 0;

out_free_stateid_slab:
        kmem_cache_destroy(stateid_slab);
out_free_file_slab:
        kmem_cache_destroy(file_slab);
out_free_lockowner_slab:
        kmem_cache_destroy(lockowner_slab);
out_free_openowner_slab:
        kmem_cache_destroy(openowner_slab);
out:
        dprintk("nfsd4: out of memory while initializing nfsv4\n");
        return -ENOMEM;
}

static void init_nfs4_replay(struct nfs4_replay *rp)
{
        rp->rp_status = nfserr_serverfault;
        rp->rp_buflen = 0;
        rp->rp_buf = rp->rp_ibuf;
        mutex_init(&rp->rp_mutex);
}

static void nfsd4_cstate_assign_replay(struct nfsd4_compound_state *cstate,
                struct nfs4_stateowner *so)
{
        if (!nfsd4_has_session(cstate)) {
                mutex_lock(&so->so_replay.rp_mutex);
                cstate->replay_owner = so;
                atomic_inc(&so->so_count);
        }
}

void nfsd4_cstate_clear_replay(struct nfsd4_compound_state *cstate)
{
        struct nfs4_stateowner *so = cstate->replay_owner;

        if (so != NULL) {
                cstate->replay_owner = NULL;
                mutex_unlock(&so->so_replay.rp_mutex);
                nfs4_put_stateowner(so);
        }
}

static inline void *alloc_stateowner(struct kmem_cache *slab, struct xdr_netobj *owner, struct nfs4_client *clp)
{
        struct nfs4_stateowner *sop;

        sop = kmem_cache_alloc(slab, GFP_KERNEL);
        if (!sop)
                return NULL;

        sop->so_owner.data = kmemdup(owner->data, owner->len, GFP_KERNEL);
        if (!sop->so_owner.data) {
                kmem_cache_free(slab, sop);
                return NULL;
        }
        sop->so_owner.len = owner->len;

        INIT_LIST_HEAD(&sop->so_stateids);
        sop->so_client = clp;
        init_nfs4_replay(&sop->so_replay);
        atomic_set(&sop->so_count, 1);
        return sop;
}

static void hash_openowner(struct nfs4_openowner *oo, struct nfs4_client *clp, unsigned int strhashval)
{
        lockdep_assert_held(&clp->cl_lock);

        list_add(&oo->oo_owner.so_strhash,
                 &clp->cl_ownerstr_hashtbl[strhashval]);
        list_add(&oo->oo_perclient, &clp->cl_openowners);
}

static void nfs4_unhash_openowner(struct nfs4_stateowner *so)
{
        unhash_openowner_locked(openowner(so));
}

static void nfs4_free_openowner(struct nfs4_stateowner *so)
{
        struct nfs4_openowner *oo = openowner(so);

        kmem_cache_free(openowner_slab, oo);
}

static const struct nfs4_stateowner_operations openowner_ops = {
        .so_unhash =    nfs4_unhash_openowner,
        .so_free =      nfs4_free_openowner,
};

static struct nfs4_openowner *
alloc_init_open_stateowner(unsigned int strhashval, struct nfsd4_open *open,
                           struct nfsd4_compound_state *cstate)
{
        struct nfs4_client *clp = cstate->clp;
        struct nfs4_openowner *oo, *ret;

        oo = alloc_stateowner(openowner_slab, &open->op_owner, clp);
        if (!oo)
                return NULL;
        oo->oo_owner.so_ops = &openowner_ops;
        oo->oo_owner.so_is_open_owner = 1;
        oo->oo_owner.so_seqid = open->op_seqid;
        oo->oo_flags = 0;
        if (nfsd4_has_session(cstate))
                oo->oo_flags |= NFS4_OO_CONFIRMED;
        oo->oo_time = 0;
        oo->oo_last_closed_stid = NULL;
        INIT_LIST_HEAD(&oo->oo_close_lru);
        spin_lock(&clp->cl_lock);
        ret = find_openstateowner_str_locked(strhashval, open, clp);
        if (ret == NULL) {
                hash_openowner(oo, clp, strhashval);
                ret = oo;
        } else
                nfs4_free_openowner(&oo->oo_owner);
        spin_unlock(&clp->cl_lock);
        return oo;
}

static void init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp, struct nfsd4_open *open) {
        struct nfs4_openowner *oo = open->op_openowner;

        atomic_inc(&stp->st_stid.sc_count);
        stp->st_stid.sc_type = NFS4_OPEN_STID;
        INIT_LIST_HEAD(&stp->st_locks);
        stp->st_stateowner = &oo->oo_owner;
        atomic_inc(&stp->st_stateowner->so_count);
        get_nfs4_file(fp);
        stp->st_stid.sc_file = fp;
        stp->st_access_bmap = 0;
        stp->st_deny_bmap = 0;
        stp->st_openstp = NULL;
        spin_lock(&oo->oo_owner.so_client->cl_lock);
        list_add(&stp->st_perstateowner, &oo->oo_owner.so_stateids);
        spin_lock(&fp->fi_lock);
        list_add(&stp->st_perfile, &fp->fi_stateids);
        spin_unlock(&fp->fi_lock);
        spin_unlock(&oo->oo_owner.so_client->cl_lock);
}

/*
 * In the 4.0 case we need to keep the owners around a little while to handle
 * CLOSE replay. We still do need to release any file access that is held by
 * them before returning however.
 */
static void
move_to_close_lru(struct nfs4_ol_stateid *s, struct net *net)
{
        struct nfs4_ol_stateid *last;
        struct nfs4_openowner *oo = openowner(s->st_stateowner);
        struct nfsd_net *nn = net_generic(s->st_stid.sc_client->net,
                                                nfsd_net_id);

        dprintk("NFSD: move_to_close_lru nfs4_openowner %p\n", oo);

        /*
         * We know that we hold one reference via nfsd4_close, and another
         * "persistent" reference for the client. If the refcount is higher
         * than 2, then there are still calls in progress that are using this
         * stateid. We can't put the sc_file reference until they are finished.
         * Wait for the refcount to drop to 2. Since it has been unhashed,
         * there should be no danger of the refcount going back up again at
         * this point.
         */
        wait_event(close_wq, atomic_read(&s->st_stid.sc_count) == 2);

        release_all_access(s);
        if (s->st_stid.sc_file) {
                put_nfs4_file(s->st_stid.sc_file);
                s->st_stid.sc_file = NULL;
        }

        spin_lock(&nn->client_lock);
        last = oo->oo_last_closed_stid;
        oo->oo_last_closed_stid = s;
        list_move_tail(&oo->oo_close_lru, &nn->close_lru);
        oo->oo_time = get_seconds();
        spin_unlock(&nn->client_lock);
        if (last)
                nfs4_put_stid(&last->st_stid);
}

/* search file_hashtbl[] for file */
static struct nfs4_file *
find_file_locked(struct knfsd_fh *fh)
{
        unsigned int hashval = file_hashval(fh);
        struct nfs4_file *fp;

        lockdep_assert_held(&state_lock);

        hlist_for_each_entry(fp, &file_hashtbl[hashval], fi_hash) {
                if (nfsd_fh_match(&fp->fi_fhandle, fh)) {
                        get_nfs4_file(fp);
                        return fp;
                }
        }
        return NULL;
}

static struct nfs4_file *
find_file(struct knfsd_fh *fh)
{
        struct nfs4_file *fp;

        spin_lock(&state_lock);
        fp = find_file_locked(fh);
        spin_unlock(&state_lock);
        return fp;
}

static struct nfs4_file *
find_or_add_file(struct nfs4_file *new, struct knfsd_fh *fh)
{
        struct nfs4_file *fp;

        spin_lock(&state_lock);
        fp = find_file_locked(fh);
        if (fp == NULL) {
                nfsd4_init_file(new, fh);
                fp = new;
        }
        spin_unlock(&state_lock);

        return fp;
}

/*
 * Called to check deny when READ with all zero stateid or
 * WRITE with all zero or all one stateid
 */
static __be32
nfs4_share_conflict(struct svc_fh *current_fh, unsigned int deny_type)
{
        struct nfs4_file *fp;
        __be32 ret = nfs_ok;

        fp = find_file(&current_fh->fh_handle);
        if (!fp)
                return ret;
        /* Check for conflicting share reservations */
        spin_lock(&fp->fi_lock);
        if (fp->fi_share_deny & deny_type)
                ret = nfserr_locked;
        spin_unlock(&fp->fi_lock);
        put_nfs4_file(fp);
        return ret;
}

void nfsd4_prepare_cb_recall(struct nfs4_delegation *dp)
{
        struct nfsd_net *nn = net_generic(dp->dl_stid.sc_client->net,
                                          nfsd_net_id);

        block_delegations(&dp->dl_stid.sc_file->fi_fhandle);

        /*
         * We can't do this in nfsd_break_deleg_cb because it is
         * already holding inode->i_lock.
         *
         * If the dl_time != 0, then we know that it has already been
         * queued for a lease break. Don't queue it again.
         */
        spin_lock(&state_lock);
        if (dp->dl_time == 0) {
                dp->dl_time = get_seconds();
                list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);
        }
        spin_unlock(&state_lock);
}

static void nfsd_break_one_deleg(struct nfs4_delegation *dp)
{
        /*
         * We're assuming the state code never drops its reference
         * without first removing the lease.  Since we're in this lease
         * callback (and since the lease code is serialized by the kernel
         * lock) we know the server hasn't removed the lease yet, we know
         * it's safe to take a reference.
         */
        atomic_inc(&dp->dl_stid.sc_count);
        nfsd4_cb_recall(dp);
}

/* Called from break_lease() with i_lock held. */
static void nfsd_break_deleg_cb(struct file_lock *fl)
{
        struct nfs4_file *fp = (struct nfs4_file *)fl->fl_owner;
        struct nfs4_delegation *dp;

        if (!fp) {
                WARN(1, "(%p)->fl_owner NULL\n", fl);
                return;
        }
        if (fp->fi_had_conflict) {
                WARN(1, "duplicate break on %p\n", fp);
                return;
        }
        /*
         * We don't want the locks code to timeout the lease for us;
         * we'll remove it ourself if a delegation isn't returned
         * in time:
         */
        fl->fl_break_time = 0;

        spin_lock(&fp->fi_lock);
        fp->fi_had_conflict = true;
        /*
         * If there are no delegations on the list, then we can't count on this
         * lease ever being cleaned up. Set the fl_break_time to jiffies so that
         * time_out_leases will do it ASAP. The fact that fi_had_conflict is now
         * true should keep any new delegations from being hashed.
         */
        if (list_empty(&fp->fi_delegations))
                fl->fl_break_time = jiffies;
        else
                list_for_each_entry(dp, &fp->fi_delegations, dl_perfile)
                        nfsd_break_one_deleg(dp);
        spin_unlock(&fp->fi_lock);
}

static
int nfsd_change_deleg_cb(struct file_lock **onlist, int arg)
{
        if (arg & F_UNLCK)
                return lease_modify(onlist, arg);
        else
                return -EAGAIN;
}

static const struct lock_manager_operations nfsd_lease_mng_ops = {
        .lm_break = nfsd_break_deleg_cb,
        .lm_change = nfsd_change_deleg_cb,
};

static __be32 nfsd4_check_seqid(struct nfsd4_compound_state *cstate, struct nfs4_stateowner *so, u32 seqid)
{
        if (nfsd4_has_session(cstate))
                return nfs_ok;
        if (seqid == so->so_seqid - 1)
                return nfserr_replay_me;
        if (seqid == so->so_seqid)
                return nfs_ok;
        return nfserr_bad_seqid;
}

static __be32 lookup_clientid(clientid_t *clid,
                struct nfsd4_compound_state *cstate,
                struct nfsd_net *nn)
{
        struct nfs4_client *found;

        if (cstate->clp) {
                found = cstate->clp;
                if (!same_clid(&found->cl_clientid, clid))
                        return nfserr_stale_clientid;
                return nfs_ok;
        }

        if (STALE_CLIENTID(clid, nn))
                return nfserr_stale_clientid;

        /*
         * For v4.1+ we get the client in the SEQUENCE op. If we don't have one
         * cached already then we know this is for is for v4.0 and "sessions"
         * will be false.
         */
        WARN_ON_ONCE(cstate->session);
        spin_lock(&nn->client_lock);
        found = find_confirmed_client(clid, false, nn);
        if (!found) {
                spin_unlock(&nn->client_lock);
                return nfserr_expired;
        }
        atomic_inc(&found->cl_refcount);
        spin_unlock(&nn->client_lock);

        /* Cache the nfs4_client in cstate! */
        cstate->clp = found;
        return nfs_ok;
}

__be32
nfsd4_process_open1(struct nfsd4_compound_state *cstate,
                    struct nfsd4_open *open, struct nfsd_net *nn)
{
        clientid_t *clientid = &open->op_clientid;
        struct nfs4_client *clp = NULL;
        unsigned int strhashval;
        struct nfs4_openowner *oo = NULL;
        __be32 status;

        if (STALE_CLIENTID(&open->op_clientid, nn))
                return nfserr_stale_clientid;
        /*
         * In case we need it later, after we've already created the
         * file and don't want to risk a further failure:
         */
        open->op_file = nfsd4_alloc_file();
        if (open->op_file == NULL)
                return nfserr_jukebox;

        status = lookup_clientid(clientid, cstate, nn);
        if (status)
                return status;
        clp = cstate->clp;

        strhashval = ownerstr_hashval(&open->op_owner);
        oo = find_openstateowner_str(strhashval, open, clp);
        open->op_openowner = oo;
        if (!oo) {
                goto new_owner;
        }
        if (!(oo->oo_flags & NFS4_OO_CONFIRMED)) {
                /* Replace unconfirmed owners without checking for replay. */
                release_openowner(oo);
                open->op_openowner = NULL;
                goto new_owner;
        }
        status = nfsd4_check_seqid(cstate, &oo->oo_owner, open->op_seqid);
        if (status)
                return status;
        goto alloc_stateid;
new_owner:
        oo = alloc_init_open_stateowner(strhashval, open, cstate);
        if (oo == NULL)
                return nfserr_jukebox;
        open->op_openowner = oo;
alloc_stateid:
        open->op_stp = nfs4_alloc_open_stateid(clp);
        if (!open->op_stp)
                return nfserr_jukebox;
        return nfs_ok;
}

static inline __be32
nfs4_check_delegmode(struct nfs4_delegation *dp, int flags)
{
        if ((flags & WR_STATE) && (dp->dl_type == NFS4_OPEN_DELEGATE_READ))
                return nfserr_openmode;
        else
                return nfs_ok;
}

static int share_access_to_flags(u32 share_access)
{
        return share_access == NFS4_SHARE_ACCESS_READ ? RD_STATE : WR_STATE;
}

static struct nfs4_delegation *find_deleg_stateid(struct nfs4_client *cl, stateid_t *s)
{
        struct nfs4_stid *ret;

        ret = find_stateid_by_type(cl, s, NFS4_DELEG_STID);
        if (!ret)
                return NULL;
        return delegstateid(ret);
}

static bool nfsd4_is_deleg_cur(struct nfsd4_open *open)
{
        return open->op_claim_type == NFS4_OPEN_CLAIM_DELEGATE_CUR ||
               open->op_claim_type == NFS4_OPEN_CLAIM_DELEG_CUR_FH;
}

static __be32
nfs4_check_deleg(struct nfs4_client *cl, struct nfsd4_open *open,
                struct nfs4_delegation **dp)
{
        int flags;
        __be32 status = nfserr_bad_stateid;
        struct nfs4_delegation *deleg;

        deleg = find_deleg_stateid(cl, &open->op_delegate_stateid);
        if (deleg == NULL)
                goto out;
        flags = share_access_to_flags(open->op_share_access);
        status = nfs4_check_delegmode(deleg, flags);
        if (status) {
                nfs4_put_stid(&deleg->dl_stid);
                goto out;
        }
        *dp = deleg;
out:
        if (!nfsd4_is_deleg_cur(open))
                return nfs_ok;
        if (status)
                return status;
        open->op_openowner->oo_flags |= NFS4_OO_CONFIRMED;
        return nfs_ok;
}

static struct nfs4_ol_stateid *
nfsd4_find_existing_open(struct nfs4_file *fp, struct nfsd4_open *open)
{
        struct nfs4_ol_stateid *local, *ret = NULL;
        struct nfs4_openowner *oo = open->op_openowner;

        spin_lock(&fp->fi_lock);
        list_for_each_entry(local, &fp->fi_stateids, st_perfile) {
                /* ignore lock owners */
                if (local->st_stateowner->so_is_open_owner == 0)
                        continue;
                if (local->st_stateowner == &oo->oo_owner) {
                        ret = local;
                        atomic_inc(&ret->st_stid.sc_count);
                        break;
                }
        }
        spin_unlock(&fp->fi_lock);
        return ret;
}

static inline int nfs4_access_to_access(u32 nfs4_access)
{
        int flags = 0;

        if (nfs4_access & NFS4_SHARE_ACCESS_READ)
                flags |= NFSD_MAY_READ;
        if (nfs4_access & NFS4_SHARE_ACCESS_WRITE)
                flags |= NFSD_MAY_WRITE;
        return flags;
}

static inline __be32
nfsd4_truncate(struct svc_rqst *rqstp, struct svc_fh *fh,
                struct nfsd4_open *open)
{
        struct iattr iattr = {
                .ia_valid = ATTR_SIZE,
                .ia_size = 0,
        };
        if (!open->op_truncate)
                return 0;
        if (!(open->op_share_access & NFS4_SHARE_ACCESS_WRITE))
                return nfserr_inval;
        return nfsd_setattr(rqstp, fh, &iattr, 0, (time_t)0);
}

static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
                struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp,
                struct nfsd4_open *open)
{
        struct file *filp = NULL;
        __be32 status;
        int oflag = nfs4_access_to_omode(open->op_share_access);
        int access = nfs4_access_to_access(open->op_share_access);
        unsigned char old_access_bmap, old_deny_bmap;

        spin_lock(&fp->fi_lock);

        /*
         * Are we trying to set a deny mode that would conflict with
         * current access?
         */
        status = nfs4_file_check_deny(fp, open->op_share_deny);
        if (status != nfs_ok) {
                spin_unlock(&fp->fi_lock);
                goto out;
        }

        /* set access to the file */
        status = nfs4_file_get_access(fp, open->op_share_access);
        if (status != nfs_ok) {
                spin_unlock(&fp->fi_lock);
                goto out;
        }

        /* Set access bits in stateid */
        old_access_bmap = stp->st_access_bmap;
        set_access(open->op_share_access, stp);

        /* Set new deny mask */
        old_deny_bmap = stp->st_deny_bmap;
        set_deny(open->op_share_deny, stp);
        fp->fi_share_deny |= (open->op_share_deny & NFS4_SHARE_DENY_BOTH);

        if (!fp->fi_fds[oflag]) {
                spin_unlock(&fp->fi_lock);
                status = nfsd_open(rqstp, cur_fh, S_IFREG, access, &filp);
                if (status)
                        goto out_put_access;
                spin_lock(&fp->fi_lock);
                if (!fp->fi_fds[oflag]) {
                        fp->fi_fds[oflag] = filp;
                        filp = NULL;
                }
        }
        spin_unlock(&fp->fi_lock);
        if (filp)
                fput(filp);

        status = nfsd4_truncate(rqstp, cur_fh, open);
        if (status)
                goto out_put_access;
out:
        return status;
out_put_access:
        stp->st_access_bmap = old_access_bmap;
        nfs4_file_put_access(fp, open->op_share_access);
        reset_union_bmap_deny(bmap_to_share_mode(old_deny_bmap), stp);
        goto out;
}

static __be32
nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp, struct nfsd4_open *open)
{
        __be32 status;
        unsigned char old_deny_bmap;

        if (!test_access(open->op_share_access, stp))
                return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open);

        /* test and set deny mode */
        spin_lock(&fp->fi_lock);
        status = nfs4_file_check_deny(fp, open->op_share_deny);
        if (status == nfs_ok) {
                old_deny_bmap = stp->st_deny_bmap;
                set_deny(open->op_share_deny, stp);
                fp->fi_share_deny |=
                                (open->op_share_deny & NFS4_SHARE_DENY_BOTH);
        }
        spin_unlock(&fp->fi_lock);

        if (status != nfs_ok)
                return status;

        status = nfsd4_truncate(rqstp, cur_fh, open);
        if (status != nfs_ok)
                reset_union_bmap_deny(old_deny_bmap, stp);
        return status;
}

static void
nfs4_set_claim_prev(struct nfsd4_open *open, bool has_session)
{
        open->op_openowner->oo_flags |= NFS4_OO_CONFIRMED;
}

/* Should we give out recallable state?: */
static bool nfsd4_cb_channel_good(struct nfs4_client *clp)
{
        if (clp->cl_cb_state == NFSD4_CB_UP)
                return true;
        /*
         * In the sessions case, since we don't have to establish a
         * separate connection for callbacks, we assume it's OK
         * until we hear otherwise:
         */
        return clp->cl_minorversion && clp->cl_cb_state == NFSD4_CB_UNKNOWN;
}

static struct file_lock *nfs4_alloc_init_lease(struct nfs4_file *fp, int flag)
{
        struct file_lock *fl;

        fl = locks_alloc_lock();
        if (!fl)
                return NULL;
        fl->fl_lmops = &nfsd_lease_mng_ops;
        fl->fl_flags = FL_DELEG;
        fl->fl_type = flag == NFS4_OPEN_DELEGATE_READ? F_RDLCK: F_WRLCK;
        fl->fl_end = OFFSET_MAX;
        fl->fl_owner = (fl_owner_t)fp;
        fl->fl_pid = current->tgid;
        return fl;
}

static int nfs4_setlease(struct nfs4_delegation *dp)
{
        struct nfs4_file *fp = dp->dl_stid.sc_file;
        struct file_lock *fl;
        struct file *filp;
        int status = 0;

        fl = nfs4_alloc_init_lease(fp, NFS4_OPEN_DELEGATE_READ);
        if (!fl)
                return -ENOMEM;
        filp = find_readable_file(fp);
        if (!filp) {
                /* We should always have a readable file here */
                WARN_ON_ONCE(1);
                return -EBADF;
        }
        fl->fl_file = filp;
        status = vfs_setlease(filp, fl->fl_type, &fl);
        if (status) {
                locks_free_lock(fl);
                goto out_fput;
        }
        spin_lock(&state_lock);
        spin_lock(&fp->fi_lock);
        /* Did the lease get broken before we took the lock? */
        status = -EAGAIN;
        if (fp->fi_had_conflict)
                goto out_unlock;
        /* Race breaker */
        if (fp->fi_lease) {
                status = 0;
                atomic_inc(&fp->fi_delegees);
                hash_delegation_locked(dp, fp);
                goto out_unlock;
        }
        fp->fi_lease = fl;
        fp->fi_deleg_file = filp;
        atomic_set(&fp->fi_delegees, 1);
        hash_delegation_locked(dp, fp);
        spin_unlock(&fp->fi_lock);
        spin_unlock(&state_lock);
        return 0;
out_unlock:
        spin_unlock(&fp->fi_lock);
        spin_unlock(&state_lock);
out_fput:
        fput(filp);
        return status;
}

static struct nfs4_delegation *
nfs4_set_delegation(struct nfs4_client *clp, struct svc_fh *fh,
                    struct nfs4_file *fp)
{
        int status;
        struct nfs4_delegation *dp;

        if (fp->fi_had_conflict)
                return ERR_PTR(-EAGAIN);

        dp = alloc_init_deleg(clp, fh);
        if (!dp)
                return ERR_PTR(-ENOMEM);

        get_nfs4_file(fp);
        spin_lock(&state_lock);
        spin_lock(&fp->fi_lock);
        dp->dl_stid.sc_file = fp;
        if (!fp->fi_lease) {
                spin_unlock(&fp->fi_lock);
                spin_unlock(&state_lock);
                status = nfs4_setlease(dp);
                goto out;
        }
        atomic_inc(&fp->fi_delegees);
        if (fp->fi_had_conflict) {
                status = -EAGAIN;
                goto out_unlock;
        }
        hash_delegation_locked(dp, fp);
        status = 0;
out_unlock:
        spin_unlock(&fp->fi_lock);
        spin_unlock(&state_lock);
out:
        if (status) {
                nfs4_put_stid(&dp->dl_stid);
                return ERR_PTR(status);
        }
        return dp;
}

static void nfsd4_open_deleg_none_ext(struct nfsd4_open *open, int status)
{
        open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE_EXT;
        if (status == -EAGAIN)
                open->op_why_no_deleg = WND4_CONTENTION;
        else {
                open->op_why_no_deleg = WND4_RESOURCE;
                switch (open->op_deleg_want) {
                case NFS4_SHARE_WANT_READ_DELEG:
                case NFS4_SHARE_WANT_WRITE_DELEG:
                case NFS4_SHARE_WANT_ANY_DELEG:
                        break;
                case NFS4_SHARE_WANT_CANCEL:
                        open->op_why_no_deleg = WND4_CANCELLED;
                        break;
                case NFS4_SHARE_WANT_NO_DELEG:
                        WARN_ON_ONCE(1);
                }
        }
}

/*
 * Attempt to hand out a delegation.
 *
 * Note we don't support write delegations, and won't until the vfs has
 * proper support for them.
 */
static void
nfs4_open_delegation(struct svc_fh *fh, struct nfsd4_open *open,
                        struct nfs4_ol_stateid *stp)
{
        struct nfs4_delegation *dp;
        struct nfs4_openowner *oo = openowner(stp->st_stateowner);
        struct nfs4_client *clp = stp->st_stid.sc_client;
        int cb_up;
        int status = 0;

        cb_up = nfsd4_cb_channel_good(oo->oo_owner.so_client);
        open->op_recall = 0;
        switch (open->op_claim_type) {
                case NFS4_OPEN_CLAIM_PREVIOUS:
                        if (!cb_up)
                                open->op_recall = 1;
                        if (open->op_delegate_type != NFS4_OPEN_DELEGATE_READ)
                                goto out_no_deleg;
                        break;
                case NFS4_OPEN_CLAIM_NULL:
                case NFS4_OPEN_CLAIM_FH:
                        /*
                         * Let's not give out any delegations till everyone's
                         * had the chance to reclaim theirs....
                         */
                        if (locks_in_grace(clp->net))
                                goto out_no_deleg;
                        if (!cb_up || !(oo->oo_flags & NFS4_OO_CONFIRMED))
                                goto out_no_deleg;
                        /*
                         * Also, if the file was opened for write or
                         * create, there's a good chance the client's
                         * about to write to it, resulting in an
                         * immediate recall (since we don't support
                         * write delegations):
                         */
                        if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE)
                                goto out_no_deleg;
                        if (open->op_create == NFS4_OPEN_CREATE)
                                goto out_no_deleg;
                        break;
                default:
                        goto out_no_deleg;
        }
        dp = nfs4_set_delegation(clp, fh, stp->st_stid.sc_file);
        if (IS_ERR(dp))
                goto out_no_deleg;

        memcpy(&open->op_delegate_stateid, &dp->dl_stid.sc_stateid, sizeof(dp->dl_stid.sc_stateid));

        dprintk("NFSD: delegation stateid=" STATEID_FMT "\n",
                STATEID_VAL(&dp->dl_stid.sc_stateid));
        open->op_delegate_type = NFS4_OPEN_DELEGATE_READ;
        nfs4_put_stid(&dp->dl_stid);
        return;
out_no_deleg:
        open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE;
        if (open->op_claim_type == NFS4_OPEN_CLAIM_PREVIOUS &&
            open->op_delegate_type != NFS4_OPEN_DELEGATE_NONE) {
                dprintk("NFSD: WARNING: refusing delegation reclaim\n");
                open->op_recall = 1;
        }

        /* 4.1 client asking for a delegation? */
        if (open->op_deleg_want)
                nfsd4_open_deleg_none_ext(open, status);
        return;
}

static void nfsd4_deleg_xgrade_none_ext(struct nfsd4_open *open,
                                        struct nfs4_delegation *dp)
{
        if (open->op_deleg_want == NFS4_SHARE_WANT_READ_DELEG &&
            dp->dl_type == NFS4_OPEN_DELEGATE_WRITE) {
                open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE_EXT;
                open->op_why_no_deleg = WND4_NOT_SUPP_DOWNGRADE;
        } else if (open->op_deleg_want == NFS4_SHARE_WANT_WRITE_DELEG &&
                   dp->dl_type == NFS4_OPEN_DELEGATE_WRITE) {
                open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE_EXT;
                open->op_why_no_deleg = WND4_NOT_SUPP_UPGRADE;
        }
        /* Otherwise the client must be confused wanting a delegation
         * it already has, therefore we don't return
         * NFS4_OPEN_DELEGATE_NONE_EXT and reason.
         */
}

__be32
nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_open *open)
{
        struct nfsd4_compoundres *resp = rqstp->rq_resp;
        struct nfs4_client *cl = open->op_openowner->oo_owner.so_client;
        struct nfs4_file *fp = NULL;
        struct nfs4_ol_stateid *stp = NULL;
        struct nfs4_delegation *dp = NULL;
        __be32 status;

        /*
         * Lookup file; if found, lookup stateid and check open request,
         * and check for delegations in the process of being recalled.
         * If not found, create the nfs4_file struct
         */
        fp = find_or_add_file(open->op_file, &current_fh->fh_handle);
        if (fp != open->op_file) {
                status = nfs4_check_deleg(cl, open, &dp);
                if (status)
                        goto out;
                stp = nfsd4_find_existing_open(fp, open);
        } else {
                open->op_file = NULL;
                status = nfserr_bad_stateid;
                if (nfsd4_is_deleg_cur(open))
                        goto out;
                status = nfserr_jukebox;
        }

        /*
         * OPEN the file, or upgrade an existing OPEN.
         * If truncate fails, the OPEN fails.
         */
        if (stp) {
                /* Stateid was found, this is an OPEN upgrade */
                status = nfs4_upgrade_open(rqstp, fp, current_fh, stp, open);
                if (status)
                        goto out;
        } else {
                stp = open->op_stp;
                open->op_stp = NULL;
                init_open_stateid(stp, fp, open);
                status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open);
                if (status) {
                        release_open_stateid(stp);
                        goto out;
                }
        }
        update_stateid(&stp->st_stid.sc_stateid);
        memcpy(&open->op_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));

        if (nfsd4_has_session(&resp->cstate)) {
                if (open->op_deleg_want & NFS4_SHARE_WANT_NO_DELEG) {
                        open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE_EXT;
                        open->op_why_no_deleg = WND4_NOT_WANTED;
                        goto nodeleg;
                }
        }

        /*
        * Attempt to hand out a delegation. No error return, because the
        * OPEN succeeds even if we fail.
        */
        nfs4_open_delegation(current_fh, open, stp);
nodeleg:
        status = nfs_ok;

        dprintk("%s: stateid=" STATEID_FMT "\n", __func__,
                STATEID_VAL(&stp->st_stid.sc_stateid));
out:
        /* 4.1 client trying to upgrade/downgrade delegation? */
        if (open->op_delegate_type == NFS4_OPEN_DELEGATE_NONE && dp &&
            open->op_deleg_want)
                nfsd4_deleg_xgrade_none_ext(open, dp);

        if (fp)
                put_nfs4_file(fp);
        if (status == 0 && open->op_claim_type == NFS4_OPEN_CLAIM_PREVIOUS)
                nfs4_set_claim_prev(open, nfsd4_has_session(&resp->cstate));
        /*
        * To finish the open response, we just need to set the rflags.
        */
        open->op_rflags = NFS4_OPEN_RESULT_LOCKTYPE_POSIX;
        if (!(open->op_openowner->oo_flags & NFS4_OO_CONFIRMED) &&
            !nfsd4_has_session(&resp->cstate))
                open->op_rflags |= NFS4_OPEN_RESULT_CONFIRM;
        if (dp)
                nfs4_put_stid(&dp->dl_stid);
        if (stp)
                nfs4_put_stid(&stp->st_stid);

        return status;
}

void nfsd4_cleanup_open_state(struct nfsd4_compound_state *cstate,
                              struct nfsd4_open *open, __be32 status)
{
        if (open->op_openowner) {
                struct nfs4_stateowner *so = &open->op_openowner->oo_owner;

                nfsd4_cstate_assign_replay(cstate, so);
                nfs4_put_stateowner(so);
        }
        if (open->op_file)
                nfsd4_free_file(open->op_file);
        if (open->op_stp)
                nfs4_put_stid(&open->op_stp->st_stid);
}

__be32
nfsd4_renew(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
            clientid_t *clid)
{
        struct nfs4_client *clp;
        __be32 status;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        dprintk("process_renew(%08x/%08x): starting\n", 
                        clid->cl_boot, clid->cl_id);
        status = lookup_clientid(clid, cstate, nn);
        if (status)
                goto out;
        clp = cstate->clp;
        status = nfserr_cb_path_down;
        if (!list_empty(&clp->cl_delegations)
                        && clp->cl_cb_state != NFSD4_CB_UP)
                goto out;
        status = nfs_ok;
out:
        return status;
}

static void
nfsd4_end_grace(struct nfsd_net *nn)
{
        /* do nothing if grace period already ended */
        if (nn->grace_ended)
                return;

        dprintk("NFSD: end of grace period\n");
        nn->grace_ended = true;
        nfsd4_record_grace_done(nn, nn->boot_time);
        locks_end_grace(&nn->nfsd4_manager);
        /*
         * Now that every NFSv4 client has had the chance to recover and
         * to see the (possibly new, possibly shorter) lease time, we
         * can safely set the next grace time to the current lease time:
         */
        nn->nfsd4_grace = nn->nfsd4_lease;
}

static time_t
nfs4_laundromat(struct nfsd_net *nn)
{
        struct nfs4_client *clp;
        struct nfs4_openowner *oo;
        struct nfs4_delegation *dp;
        struct nfs4_ol_stateid *stp;
        struct list_head *pos, *next, reaplist;
        time_t cutoff = get_seconds() - nn->nfsd4_lease;
        time_t t, new_timeo = nn->nfsd4_lease;

        dprintk("NFSD: laundromat service - starting\n");
        nfsd4_end_grace(nn);
        INIT_LIST_HEAD(&reaplist);
        spin_lock(&nn->client_lock);
        list_for_each_safe(pos, next, &nn->client_lru) {
                clp = list_entry(pos, struct nfs4_client, cl_lru);
                if (time_after((unsigned long)clp->cl_time, (unsigned long)cutoff)) {
                        t = clp->cl_time - cutoff;
                        new_timeo = min(new_timeo, t);
                        break;
                }
                if (mark_client_expired_locked(clp)) {
                        dprintk("NFSD: client in use (clientid %08x)\n",
                                clp->cl_clientid.cl_id);
                        continue;
                }
                list_add(&clp->cl_lru, &reaplist);
        }
        spin_unlock(&nn->client_lock);
        list_for_each_safe(pos, next, &reaplist) {
                clp = list_entry(pos, struct nfs4_client, cl_lru);
                dprintk("NFSD: purging unused client (clientid %08x)\n",
                        clp->cl_clientid.cl_id);
                list_del_init(&clp->cl_lru);
                expire_client(clp);
        }
        spin_lock(&state_lock);
        list_for_each_safe(pos, next, &nn->del_recall_lru) {
                dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
                if (net_generic(dp->dl_stid.sc_client->net, nfsd_net_id) != nn)
                        continue;
                if (time_after((unsigned long)dp->dl_time, (unsigned long)cutoff)) {
                        t = dp->dl_time - cutoff;
                        new_timeo = min(new_timeo, t);
                        break;
                }
                unhash_delegation_locked(dp);
                list_add(&dp->dl_recall_lru, &reaplist);
        }
        spin_unlock(&state_lock);
        while (!list_empty(&reaplist)) {
                dp = list_first_entry(&reaplist, struct nfs4_delegation,
                                        dl_recall_lru);
                list_del_init(&dp->dl_recall_lru);
                revoke_delegation(dp);
        }

        spin_lock(&nn->client_lock);
        while (!list_empty(&nn->close_lru)) {
                oo = list_first_entry(&nn->close_lru, struct nfs4_openowner,
                                        oo_close_lru);
                if (time_after((unsigned long)oo->oo_time,
                               (unsigned long)cutoff)) {
                        t = oo->oo_time - cutoff;
                        new_timeo = min(new_timeo, t);
                        break;
                }
                list_del_init(&oo->oo_close_lru);
                stp = oo->oo_last_closed_stid;
                oo->oo_last_closed_stid = NULL;
                spin_unlock(&nn->client_lock);
                nfs4_put_stid(&stp->st_stid);
                spin_lock(&nn->client_lock);
        }
        spin_unlock(&nn->client_lock);

        new_timeo = max_t(time_t, new_timeo, NFSD_LAUNDROMAT_MINTIMEOUT);
        return new_timeo;
}

static struct workqueue_struct *laundry_wq;
static void laundromat_main(struct work_struct *);

static void
laundromat_main(struct work_struct *laundry)
{
        time_t t;
        struct delayed_work *dwork = container_of(laundry, struct delayed_work,
                                                  work);
        struct nfsd_net *nn = container_of(dwork, struct nfsd_net,
                                           laundromat_work);

        t = nfs4_laundromat(nn);
        dprintk("NFSD: laundromat_main - sleeping for %ld seconds\n", t);
        queue_delayed_work(laundry_wq, &nn->laundromat_work, t*HZ);
}

static inline __be32 nfs4_check_fh(struct svc_fh *fhp, struct nfs4_ol_stateid *stp)
{
        if (!nfsd_fh_match(&fhp->fh_handle, &stp->st_stid.sc_file->fi_fhandle))
                return nfserr_bad_stateid;
        return nfs_ok;
}

static inline int
access_permit_read(struct nfs4_ol_stateid *stp)
{
        return test_access(NFS4_SHARE_ACCESS_READ, stp) ||
                test_access(NFS4_SHARE_ACCESS_BOTH, stp) ||
                test_access(NFS4_SHARE_ACCESS_WRITE, stp);
}

static inline int
access_permit_write(struct nfs4_ol_stateid *stp)
{
        return test_access(NFS4_SHARE_ACCESS_WRITE, stp) ||
                test_access(NFS4_SHARE_ACCESS_BOTH, stp);
}

static
__be32 nfs4_check_openmode(struct nfs4_ol_stateid *stp, int flags)
{
        __be32 status = nfserr_openmode;

        /* For lock stateid's, we test the parent open, not the lock: */
        if (stp->st_openstp)
                stp = stp->st_openstp;
        if ((flags & WR_STATE) && !access_permit_write(stp))
                goto out;
        if ((flags & RD_STATE) && !access_permit_read(stp))
                goto out;
        status = nfs_ok;
out:
        return status;
}

static inline __be32
check_special_stateids(struct net *net, svc_fh *current_fh, stateid_t *stateid, int flags)
{
        if (ONE_STATEID(stateid) && (flags & RD_STATE))
                return nfs_ok;
        else if (locks_in_grace(net)) {
                /* Answer in remaining cases depends on existence of
                 * conflicting state; so we must wait out the grace period. */
                return nfserr_grace;
        } else if (flags & WR_STATE)
                return nfs4_share_conflict(current_fh,
                                NFS4_SHARE_DENY_WRITE);
        else /* (flags & RD_STATE) && ZERO_STATEID(stateid) */
                return nfs4_share_conflict(current_fh,
                                NFS4_SHARE_DENY_READ);
}

/*
 * Allow READ/WRITE during grace period on recovered state only for files
 * that are not able to provide mandatory locking.
 */
static inline int
grace_disallows_io(struct net *net, struct inode *inode)
{
        return locks_in_grace(net) && mandatory_lock(inode);
}

/* Returns true iff a is later than b: */
static bool stateid_generation_after(stateid_t *a, stateid_t *b)
{
        return (s32)(a->si_generation - b->si_generation) > 0;
}

static __be32 check_stateid_generation(stateid_t *in, stateid_t *ref, bool has_session)
{
        /*
         * When sessions are used the stateid generation number is ignored
         * when it is zero.
         */
        if (has_session && in->si_generation == 0)
                return nfs_ok;

        if (in->si_generation == ref->si_generation)
                return nfs_ok;

        /* If the client sends us a stateid from the future, it's buggy: */
        if (stateid_generation_after(in, ref))
                return nfserr_bad_stateid;
        /*
         * However, we could see a stateid from the past, even from a
         * non-buggy client.  For example, if the client sends a lock
         * while some IO is outstanding, the lock may bump si_generation
         * while the IO is still in flight.  The client could avoid that
         * situation by waiting for responses on all the IO requests,
         * but better performance may result in retrying IO that
         * receives an old_stateid error if requests are rarely
         * reordered in flight:
         */
        return nfserr_old_stateid;
}

static __be32 nfsd4_validate_stateid(struct nfs4_client *cl, stateid_t *stateid)
{
        struct nfs4_stid *s;
        struct nfs4_ol_stateid *ols;
        __be32 status = nfserr_bad_stateid;

        if (ZERO_STATEID(stateid) || ONE_STATEID(stateid))
                return status;
        /* Client debugging aid. */
        if (!same_clid(&stateid->si_opaque.so_clid, &cl->cl_clientid)) {
                char addr_str[INET6_ADDRSTRLEN];
                rpc_ntop((struct sockaddr *)&cl->cl_addr, addr_str,
                                 sizeof(addr_str));
                pr_warn_ratelimited("NFSD: client %s testing state ID "
                                        "with incorrect client ID\n", addr_str);
                return status;
        }
        spin_lock(&cl->cl_lock);
        s = find_stateid_locked(cl, stateid);
        if (!s)
                goto out_unlock;
        status = check_stateid_generation(stateid, &s->sc_stateid, 1);
        if (status)
                goto out_unlock;
        switch (s->sc_type) {
        case NFS4_DELEG_STID:
                status = nfs_ok;
                break;
        case NFS4_REVOKED_DELEG_STID:
                status = nfserr_deleg_revoked;
                break;
        case NFS4_OPEN_STID:
        case NFS4_LOCK_STID:
                ols = openlockstateid(s);
                if (ols->st_stateowner->so_is_open_owner
                                && !(openowner(ols->st_stateowner)->oo_flags
                                                & NFS4_OO_CONFIRMED))
                        status = nfserr_bad_stateid;
                else
                        status = nfs_ok;
                break;
        default:
                printk("unknown stateid type %x\n", s->sc_type);
                /* Fallthrough */
        case NFS4_CLOSED_STID:
        case NFS4_CLOSED_DELEG_STID:
                status = nfserr_bad_stateid;
        }
out_unlock:
        spin_unlock(&cl->cl_lock);
        return status;
}

static __be32
nfsd4_lookup_stateid(struct nfsd4_compound_state *cstate,
                     stateid_t *stateid, unsigned char typemask,
                     struct nfs4_stid **s, struct nfsd_net *nn)
{
        __be32 status;

        if (ZERO_STATEID(stateid) || ONE_STATEID(stateid))
                return nfserr_bad_stateid;
        status = lookup_clientid(&stateid->si_opaque.so_clid, cstate, nn);
        if (status == nfserr_stale_clientid) {
                if (cstate->session)
                        return nfserr_bad_stateid;
                return nfserr_stale_stateid;
        }
        if (status)
                return status;
        *s = find_stateid_by_type(cstate->clp, stateid, typemask);
        if (!*s)
                return nfserr_bad_stateid;
        return nfs_ok;
}

/*
* Checks for stateid operations
*/
__be32
nfs4_preprocess_stateid_op(struct net *net, struct nfsd4_compound_state *cstate,
                           stateid_t *stateid, int flags, struct file **filpp)
{
        struct nfs4_stid *s;
        struct nfs4_ol_stateid *stp = NULL;
        struct nfs4_delegation *dp = NULL;
        struct svc_fh *current_fh = &cstate->current_fh;
        struct inode *ino = current_fh->fh_dentry->d_inode;
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);
        struct file *file = NULL;
        __be32 status;

        if (filpp)
                *filpp = NULL;

        if (grace_disallows_io(net, ino))
                return nfserr_grace;

        if (ZERO_STATEID(stateid) || ONE_STATEID(stateid))
                return check_special_stateids(net, current_fh, stateid, flags);

        status = nfsd4_lookup_stateid(cstate, stateid,
                                NFS4_DELEG_STID|NFS4_OPEN_STID|NFS4_LOCK_STID,
                                &s, nn);
        if (status)
                return status;
        status = check_stateid_generation(stateid, &s->sc_stateid, nfsd4_has_session(cstate));
        if (status)
                goto out;
        switch (s->sc_type) {
        case NFS4_DELEG_STID:
                dp = delegstateid(s);
                status = nfs4_check_delegmode(dp, flags);
                if (status)
                        goto out;
                if (filpp) {
                        file = dp->dl_stid.sc_file->fi_deleg_file;
                        if (!file) {
                                WARN_ON_ONCE(1);
                                status = nfserr_serverfault;
                                goto out;
                        }
                        get_file(file);
                }
                break;
        case NFS4_OPEN_STID:
        case NFS4_LOCK_STID:
                stp = openlockstateid(s);
                status = nfs4_check_fh(current_fh, stp);
                if (status)
                        goto out;
                if (stp->st_stateowner->so_is_open_owner
                    && !(openowner(stp->st_stateowner)->oo_flags & NFS4_OO_CONFIRMED))
                        goto out;
                status = nfs4_check_openmode(stp, flags);
                if (status)
                        goto out;
                if (filpp) {
                        struct nfs4_file *fp = stp->st_stid.sc_file;

                        if (flags & RD_STATE)
                                file = find_readable_file(fp);
                        else
                                file = find_writeable_file(fp);
                }
                break;
        default:
                status = nfserr_bad_stateid;
                goto out;
        }
        status = nfs_ok;
        if (file)
                *filpp = file;
out:
        nfs4_put_stid(s);
        return status;
}

/*
 * Test if the stateid is valid
 */
__be32
nfsd4_test_stateid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                   struct nfsd4_test_stateid *test_stateid)
{
        struct nfsd4_test_stateid_id *stateid;
        struct nfs4_client *cl = cstate->session->se_client;

        list_for_each_entry(stateid, &test_stateid->ts_stateid_list, ts_id_list)
                stateid->ts_id_status =
                        nfsd4_validate_stateid(cl, &stateid->ts_id_stateid);

        return nfs_ok;
}

__be32
nfsd4_free_stateid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                   struct nfsd4_free_stateid *free_stateid)
{
        stateid_t *stateid = &free_stateid->fr_stateid;
        struct nfs4_stid *s;
        struct nfs4_delegation *dp;
        struct nfs4_ol_stateid *stp;
        struct nfs4_client *cl = cstate->session->se_client;
        __be32 ret = nfserr_bad_stateid;

        spin_lock(&cl->cl_lock);
        s = find_stateid_locked(cl, stateid);
        if (!s)
                goto out_unlock;
        switch (s->sc_type) {
        case NFS4_DELEG_STID:
                ret = nfserr_locks_held;
                break;
        case NFS4_OPEN_STID:
                ret = check_stateid_generation(stateid, &s->sc_stateid, 1);
                if (ret)
                        break;
                ret = nfserr_locks_held;
                break;
        case NFS4_LOCK_STID:
                ret = check_stateid_generation(stateid, &s->sc_stateid, 1);
                if (ret)
                        break;
                stp = openlockstateid(s);
                ret = nfserr_locks_held;
                if (check_for_locks(stp->st_stid.sc_file,
                                    lockowner(stp->st_stateowner)))
                        break;
                unhash_lock_stateid(stp);
                spin_unlock(&cl->cl_lock);
                nfs4_put_stid(s);
                ret = nfs_ok;
                goto out;
        case NFS4_REVOKED_DELEG_STID:
                dp = delegstateid(s);
                list_del_init(&dp->dl_recall_lru);
                spin_unlock(&cl->cl_lock);
                nfs4_put_stid(s);
                ret = nfs_ok;
                goto out;
        /* Default falls through and returns nfserr_bad_stateid */
        }
out_unlock:
        spin_unlock(&cl->cl_lock);
out:
        return ret;
}

static inline int
setlkflg (int type)
{
        return (type == NFS4_READW_LT || type == NFS4_READ_LT) ?
                RD_STATE : WR_STATE;
}

static __be32 nfs4_seqid_op_checks(struct nfsd4_compound_state *cstate, stateid_t *stateid, u32 seqid, struct nfs4_ol_stateid *stp)
{
        struct svc_fh *current_fh = &cstate->current_fh;
        struct nfs4_stateowner *sop = stp->st_stateowner;
        __be32 status;

        status = nfsd4_check_seqid(cstate, sop, seqid);
        if (status)
                return status;
        if (stp->st_stid.sc_type == NFS4_CLOSED_STID
                || stp->st_stid.sc_type == NFS4_REVOKED_DELEG_STID)
                /*
                 * "Closed" stateid's exist *only* to return
                 * nfserr_replay_me from the previous step, and
                 * revoked delegations are kept only for free_stateid.
                 */
                return nfserr_bad_stateid;
        status = check_stateid_generation(stateid, &stp->st_stid.sc_stateid, nfsd4_has_session(cstate));
        if (status)
                return status;
        return nfs4_check_fh(current_fh, stp);
}

/* 
 * Checks for sequence id mutating operations. 
 */
static __be32
nfs4_preprocess_seqid_op(struct nfsd4_compound_state *cstate, u32 seqid,
                         stateid_t *stateid, char typemask,
                         struct nfs4_ol_stateid **stpp,
                         struct nfsd_net *nn)
{
        __be32 status;
        struct nfs4_stid *s;
        struct nfs4_ol_stateid *stp = NULL;

        dprintk("NFSD: %s: seqid=%d stateid = " STATEID_FMT "\n", __func__,
                seqid, STATEID_VAL(stateid));

        *stpp = NULL;
        status = nfsd4_lookup_stateid(cstate, stateid, typemask, &s, nn);
        if (status)
                return status;
        stp = openlockstateid(s);
        nfsd4_cstate_assign_replay(cstate, stp->st_stateowner);

        status = nfs4_seqid_op_checks(cstate, stateid, seqid, stp);
        if (!status)
                *stpp = stp;
        else
                nfs4_put_stid(&stp->st_stid);
        return status;
}

static __be32 nfs4_preprocess_confirmed_seqid_op(struct nfsd4_compound_state *cstate, u32 seqid,
                                                 stateid_t *stateid, struct nfs4_ol_stateid **stpp, struct nfsd_net *nn)
{
        __be32 status;
        struct nfs4_openowner *oo;
        struct nfs4_ol_stateid *stp;

        status = nfs4_preprocess_seqid_op(cstate, seqid, stateid,
                                                NFS4_OPEN_STID, &stp, nn);
        if (status)
                return status;
        oo = openowner(stp->st_stateowner);
        if (!(oo->oo_flags & NFS4_OO_CONFIRMED)) {
                nfs4_put_stid(&stp->st_stid);
                return nfserr_bad_stateid;
        }
        *stpp = stp;
        return nfs_ok;
}

__be32
nfsd4_open_confirm(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                   struct nfsd4_open_confirm *oc)
{
        __be32 status;
        struct nfs4_openowner *oo;
        struct nfs4_ol_stateid *stp;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        dprintk("NFSD: nfsd4_open_confirm on file %pd\n",
                        cstate->current_fh.fh_dentry);

        status = fh_verify(rqstp, &cstate->current_fh, S_IFREG, 0);
        if (status)
                return status;

        status = nfs4_preprocess_seqid_op(cstate,
                                        oc->oc_seqid, &oc->oc_req_stateid,
                                        NFS4_OPEN_STID, &stp, nn);
        if (status)
                goto out;
        oo = openowner(stp->st_stateowner);
        status = nfserr_bad_stateid;
        if (oo->oo_flags & NFS4_OO_CONFIRMED)
                goto put_stateid;
        oo->oo_flags |= NFS4_OO_CONFIRMED;
        update_stateid(&stp->st_stid.sc_stateid);
        memcpy(&oc->oc_resp_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));
        dprintk("NFSD: %s: success, seqid=%d stateid=" STATEID_FMT "\n",
                __func__, oc->oc_seqid, STATEID_VAL(&stp->st_stid.sc_stateid));

        nfsd4_client_record_create(oo->oo_owner.so_client);
        status = nfs_ok;
put_stateid:
        nfs4_put_stid(&stp->st_stid);
out:
        nfsd4_bump_seqid(cstate, status);
        return status;
}

static inline void nfs4_stateid_downgrade_bit(struct nfs4_ol_stateid *stp, u32 access)
{
        if (!test_access(access, stp))
                return;
        nfs4_file_put_access(stp->st_stid.sc_file, access);
        clear_access(access, stp);
}

static inline void nfs4_stateid_downgrade(struct nfs4_ol_stateid *stp, u32 to_access)
{
        switch (to_access) {
        case NFS4_SHARE_ACCESS_READ:
                nfs4_stateid_downgrade_bit(stp, NFS4_SHARE_ACCESS_WRITE);
                nfs4_stateid_downgrade_bit(stp, NFS4_SHARE_ACCESS_BOTH);
                break;
        case NFS4_SHARE_ACCESS_WRITE:
                nfs4_stateid_downgrade_bit(stp, NFS4_SHARE_ACCESS_READ);
                nfs4_stateid_downgrade_bit(stp, NFS4_SHARE_ACCESS_BOTH);
                break;
        case NFS4_SHARE_ACCESS_BOTH:
                break;
        default:
                WARN_ON_ONCE(1);
        }
}

__be32
nfsd4_open_downgrade(struct svc_rqst *rqstp,
                     struct nfsd4_compound_state *cstate,
                     struct nfsd4_open_downgrade *od)
{
        __be32 status;
        struct nfs4_ol_stateid *stp;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        dprintk("NFSD: nfsd4_open_downgrade on file %pd\n", 
                        cstate->current_fh.fh_dentry);

        /* We don't yet support WANT bits: */
        if (od->od_deleg_want)
                dprintk("NFSD: %s: od_deleg_want=0x%x ignored\n", __func__,
                        od->od_deleg_want);

        status = nfs4_preprocess_confirmed_seqid_op(cstate, od->od_seqid,
                                        &od->od_stateid, &stp, nn);
        if (status)
                goto out; 
        status = nfserr_inval;
        if (!test_access(od->od_share_access, stp)) {
                dprintk("NFSD: access not a subset of current bitmap: 0x%hhx, input access=%08x\n",
                        stp->st_access_bmap, od->od_share_access);
                goto put_stateid;
        }
        if (!test_deny(od->od_share_deny, stp)) {
                dprintk("NFSD: deny not a subset of current bitmap: 0x%hhx, input deny=%08x\n",
                        stp->st_deny_bmap, od->od_share_deny);
                goto put_stateid;
        }
        nfs4_stateid_downgrade(stp, od->od_share_access);

        reset_union_bmap_deny(od->od_share_deny, stp);

        update_stateid(&stp->st_stid.sc_stateid);
        memcpy(&od->od_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));
        status = nfs_ok;
put_stateid:
        nfs4_put_stid(&stp->st_stid);
out:
        nfsd4_bump_seqid(cstate, status);
        return status;
}

static void nfsd4_close_open_stateid(struct nfs4_ol_stateid *s)
{
        struct nfs4_client *clp = s->st_stid.sc_client;
        LIST_HEAD(reaplist);

        s->st_stid.sc_type = NFS4_CLOSED_STID;
        spin_lock(&clp->cl_lock);
        unhash_open_stateid(s, &reaplist);

        if (clp->cl_minorversion) {
                put_ol_stateid_locked(s, &reaplist);
                spin_unlock(&clp->cl_lock);
                free_ol_stateid_reaplist(&reaplist);
        } else {
                spin_unlock(&clp->cl_lock);
                free_ol_stateid_reaplist(&reaplist);
                move_to_close_lru(s, clp->net);
        }
}

/*
 * nfs4_unlock_state() called after encode
 */
__be32
nfsd4_close(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
            struct nfsd4_close *close)
{
        __be32 status;
        struct nfs4_ol_stateid *stp;
        struct net *net = SVC_NET(rqstp);
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        dprintk("NFSD: nfsd4_close on file %pd\n", 
                        cstate->current_fh.fh_dentry);

        status = nfs4_preprocess_seqid_op(cstate, close->cl_seqid,
                                        &close->cl_stateid,
                                        NFS4_OPEN_STID|NFS4_CLOSED_STID,
                                        &stp, nn);
        nfsd4_bump_seqid(cstate, status);
        if (status)
                goto out; 
        update_stateid(&stp->st_stid.sc_stateid);
        memcpy(&close->cl_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));

        nfsd4_close_open_stateid(stp);

        /* put reference from nfs4_preprocess_seqid_op */
        nfs4_put_stid(&stp->st_stid);
out:
        return status;
}

__be32
nfsd4_delegreturn(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                  struct nfsd4_delegreturn *dr)
{
        struct nfs4_delegation *dp;
        stateid_t *stateid = &dr->dr_stateid;
        struct nfs4_stid *s;
        __be32 status;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        if ((status = fh_verify(rqstp, &cstate->current_fh, S_IFREG, 0)))
                return status;

        status = nfsd4_lookup_stateid(cstate, stateid, NFS4_DELEG_STID, &s, nn);
        if (status)
                goto out;
        dp = delegstateid(s);
        status = check_stateid_generation(stateid, &dp->dl_stid.sc_stateid, nfsd4_has_session(cstate));
        if (status)
                goto put_stateid;

        destroy_delegation(dp);
put_stateid:
        nfs4_put_stid(&dp->dl_stid);
out:
        return status;
}


#define LOFF_OVERFLOW(start, len)      ((u64)(len) > ~(u64)(start))

static inline u64
end_offset(u64 start, u64 len)
{
        u64 end;

        end = start + len;
        return end >= start ? end: NFS4_MAX_UINT64;
}

/* last octet in a range */
static inline u64
last_byte_offset(u64 start, u64 len)
{
        u64 end;

        WARN_ON_ONCE(!len);
        end = start + len;
        return end > start ? end - 1: NFS4_MAX_UINT64;
}

/*
 * TODO: Linux file offsets are _signed_ 64-bit quantities, which means that
 * we can't properly handle lock requests that go beyond the (2^63 - 1)-th
 * byte, because of sign extension problems.  Since NFSv4 calls for 64-bit
 * locking, this prevents us from being completely protocol-compliant.  The
 * real solution to this problem is to start using unsigned file offsets in
 * the VFS, but this is a very deep change!
 */
static inline void
nfs4_transform_lock_offset(struct file_lock *lock)
{
        if (lock->fl_start < 0)
                lock->fl_start = OFFSET_MAX;
        if (lock->fl_end < 0)
                lock->fl_end = OFFSET_MAX;
}

/* Hack!: For now, we're defining this just so we can use a pointer to it
 * as a unique cookie to identify our (NFSv4's) posix locks. */
static const struct lock_manager_operations nfsd_posix_mng_ops  = {
};

static inline void
nfs4_set_lock_denied(struct file_lock *fl, struct nfsd4_lock_denied *deny)
{
        struct nfs4_lockowner *lo;

        if (fl->fl_lmops == &nfsd_posix_mng_ops) {
                lo = (struct nfs4_lockowner *) fl->fl_owner;
                deny->ld_owner.data = kmemdup(lo->lo_owner.so_owner.data,
                                        lo->lo_owner.so_owner.len, GFP_KERNEL);
                if (!deny->ld_owner.data)
                        /* We just don't care that much */
                        goto nevermind;
                deny->ld_owner.len = lo->lo_owner.so_owner.len;
                deny->ld_clientid = lo->lo_owner.so_client->cl_clientid;
        } else {
nevermind:
                deny->ld_owner.len = 0;
                deny->ld_owner.data = NULL;
                deny->ld_clientid.cl_boot = 0;
                deny->ld_clientid.cl_id = 0;
        }
        deny->ld_start = fl->fl_start;
        deny->ld_length = NFS4_MAX_UINT64;
        if (fl->fl_end != NFS4_MAX_UINT64)
                deny->ld_length = fl->fl_end - fl->fl_start + 1;        
        deny->ld_type = NFS4_READ_LT;
        if (fl->fl_type != F_RDLCK)
                deny->ld_type = NFS4_WRITE_LT;
}

static struct nfs4_lockowner *
find_lockowner_str_locked(clientid_t *clid, struct xdr_netobj *owner,
                struct nfs4_client *clp)
{
        unsigned int strhashval = ownerstr_hashval(owner);
        struct nfs4_stateowner *so;

        lockdep_assert_held(&clp->cl_lock);

        list_for_each_entry(so, &clp->cl_ownerstr_hashtbl[strhashval],
                            so_strhash) {
                if (so->so_is_open_owner)
                        continue;
                if (!same_owner_str(so, owner))
                        continue;
                atomic_inc(&so->so_count);
                return lockowner(so);
        }
        return NULL;
}

static struct nfs4_lockowner *
find_lockowner_str(clientid_t *clid, struct xdr_netobj *owner,
                struct nfs4_client *clp)
{
        struct nfs4_lockowner *lo;

        spin_lock(&clp->cl_lock);
        lo = find_lockowner_str_locked(clid, owner, clp);
        spin_unlock(&clp->cl_lock);
        return lo;
}

static void nfs4_unhash_lockowner(struct nfs4_stateowner *sop)
{
        unhash_lockowner_locked(lockowner(sop));
}

static void nfs4_free_lockowner(struct nfs4_stateowner *sop)
{
        struct nfs4_lockowner *lo = lockowner(sop);

        kmem_cache_free(lockowner_slab, lo);
}

static const struct nfs4_stateowner_operations lockowner_ops = {
        .so_unhash =    nfs4_unhash_lockowner,
        .so_free =      nfs4_free_lockowner,
};

/*
 * Alloc a lock owner structure.
 * Called in nfsd4_lock - therefore, OPEN and OPEN_CONFIRM (if needed) has 
 * occurred. 
 *
 * strhashval = ownerstr_hashval
 */
static struct nfs4_lockowner *
alloc_init_lock_stateowner(unsigned int strhashval, struct nfs4_client *clp,
                           struct nfs4_ol_stateid *open_stp,
                           struct nfsd4_lock *lock)
{
        struct nfs4_lockowner *lo, *ret;

        lo = alloc_stateowner(lockowner_slab, &lock->lk_new_owner, clp);
        if (!lo)
                return NULL;
        INIT_LIST_HEAD(&lo->lo_owner.so_stateids);
        lo->lo_owner.so_is_open_owner = 0;
        lo->lo_owner.so_seqid = lock->lk_new_lock_seqid;
        lo->lo_owner.so_ops = &lockowner_ops;
        spin_lock(&clp->cl_lock);
        ret = find_lockowner_str_locked(&clp->cl_clientid,
                        &lock->lk_new_owner, clp);
        if (ret == NULL) {
                list_add(&lo->lo_owner.so_strhash,
                         &clp->cl_ownerstr_hashtbl[strhashval]);
                ret = lo;
        } else
                nfs4_free_lockowner(&lo->lo_owner);
        spin_unlock(&clp->cl_lock);
        return lo;
}

static void
init_lock_stateid(struct nfs4_ol_stateid *stp, struct nfs4_lockowner *lo,
                  struct nfs4_file *fp, struct inode *inode,
                  struct nfs4_ol_stateid *open_stp)
{
        struct nfs4_client *clp = lo->lo_owner.so_client;

        lockdep_assert_held(&clp->cl_lock);

        atomic_inc(&stp->st_stid.sc_count);
        stp->st_stid.sc_type = NFS4_LOCK_STID;
        stp->st_stateowner = &lo->lo_owner;
        atomic_inc(&lo->lo_owner.so_count);
        get_nfs4_file(fp);
        stp->st_stid.sc_file = fp;
        stp->st_stid.sc_free = nfs4_free_lock_stateid;
        stp->st_access_bmap = 0;
        stp->st_deny_bmap = open_stp->st_deny_bmap;
        stp->st_openstp = open_stp;
        list_add(&stp->st_locks, &open_stp->st_locks);
        list_add(&stp->st_perstateowner, &lo->lo_owner.so_stateids);
        spin_lock(&fp->fi_lock);
        list_add(&stp->st_perfile, &fp->fi_stateids);
        spin_unlock(&fp->fi_lock);
}

static struct nfs4_ol_stateid *
find_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fp)
{
        struct nfs4_ol_stateid *lst;
        struct nfs4_client *clp = lo->lo_owner.so_client;

        lockdep_assert_held(&clp->cl_lock);

        list_for_each_entry(lst, &lo->lo_owner.so_stateids, st_perstateowner) {
                if (lst->st_stid.sc_file == fp) {
                        atomic_inc(&lst->st_stid.sc_count);
                        return lst;
                }
        }
        return NULL;
}

static struct nfs4_ol_stateid *
find_or_create_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fi,
                            struct inode *inode, struct nfs4_ol_stateid *ost,
                            bool *new)
{
        struct nfs4_stid *ns = NULL;
        struct nfs4_ol_stateid *lst;
        struct nfs4_openowner *oo = openowner(ost->st_stateowner);
        struct nfs4_client *clp = oo->oo_owner.so_client;

        spin_lock(&clp->cl_lock);
        lst = find_lock_stateid(lo, fi);
        if (lst == NULL) {
                spin_unlock(&clp->cl_lock);
                ns = nfs4_alloc_stid(clp, stateid_slab);
                if (ns == NULL)
                        return NULL;

                spin_lock(&clp->cl_lock);
                lst = find_lock_stateid(lo, fi);
                if (likely(!lst)) {
                        lst = openlockstateid(ns);
                        init_lock_stateid(lst, lo, fi, inode, ost);
                        ns = NULL;
                        *new = true;
                }
        }
        spin_unlock(&clp->cl_lock);
        if (ns)
                nfs4_put_stid(ns);
        return lst;
}

static int
check_lock_length(u64 offset, u64 length)
{
        return ((length == 0)  || ((length != NFS4_MAX_UINT64) &&
             LOFF_OVERFLOW(offset, length)));
}

static void get_lock_access(struct nfs4_ol_stateid *lock_stp, u32 access)
{
        struct nfs4_file *fp = lock_stp->st_stid.sc_file;

        lockdep_assert_held(&fp->fi_lock);

        if (test_access(access, lock_stp))
                return;
        __nfs4_file_get_access(fp, access);
        set_access(access, lock_stp);
}

static __be32
lookup_or_create_lock_state(struct nfsd4_compound_state *cstate,
                            struct nfs4_ol_stateid *ost,
                            struct nfsd4_lock *lock,
                            struct nfs4_ol_stateid **lst, bool *new)
{
        __be32 status;
        struct nfs4_file *fi = ost->st_stid.sc_file;
        struct nfs4_openowner *oo = openowner(ost->st_stateowner);
        struct nfs4_client *cl = oo->oo_owner.so_client;
        struct inode *inode = cstate->current_fh.fh_dentry->d_inode;
        struct nfs4_lockowner *lo;
        unsigned int strhashval;

        lo = find_lockowner_str(&cl->cl_clientid, &lock->v.new.owner, cl);
        if (!lo) {
                strhashval = ownerstr_hashval(&lock->v.new.owner);
                lo = alloc_init_lock_stateowner(strhashval, cl, ost, lock);
                if (lo == NULL)
                        return nfserr_jukebox;
        } else {
                /* with an existing lockowner, seqids must be the same */
                status = nfserr_bad_seqid;
                if (!cstate->minorversion &&
                    lock->lk_new_lock_seqid != lo->lo_owner.so_seqid)
                        goto out;
        }

        *lst = find_or_create_lock_stateid(lo, fi, inode, ost, new);
        if (*lst == NULL) {
                status = nfserr_jukebox;
                goto out;
        }
        status = nfs_ok;
out:
        nfs4_put_stateowner(&lo->lo_owner);
        return status;
}

/*
 *  LOCK operation 
 */
__be32
nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
           struct nfsd4_lock *lock)
{
        struct nfs4_openowner *open_sop = NULL;
        struct nfs4_lockowner *lock_sop = NULL;
        struct nfs4_ol_stateid *lock_stp = NULL;
        struct nfs4_ol_stateid *open_stp = NULL;
        struct nfs4_file *fp;
        struct file *filp = NULL;
        struct file_lock *file_lock = NULL;
        struct file_lock *conflock = NULL;
        __be32 status = 0;
        int lkflg;
        int err;
        bool new = false;
        struct net *net = SVC_NET(rqstp);
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        dprintk("NFSD: nfsd4_lock: start=%Ld length=%Ld\n",
                (long long) lock->lk_offset,
                (long long) lock->lk_length);

        if (check_lock_length(lock->lk_offset, lock->lk_length))
                 return nfserr_inval;

        if ((status = fh_verify(rqstp, &cstate->current_fh,
                                S_IFREG, NFSD_MAY_LOCK))) {
                dprintk("NFSD: nfsd4_lock: permission denied!\n");
                return status;
        }

        if (lock->lk_is_new) {
                if (nfsd4_has_session(cstate))
                        /* See rfc 5661 18.10.3: given clientid is ignored: */
                        memcpy(&lock->v.new.clientid,
                                &cstate->session->se_client->cl_clientid,
                                sizeof(clientid_t));

                status = nfserr_stale_clientid;
                if (STALE_CLIENTID(&lock->lk_new_clientid, nn))
                        goto out;

                /* validate and update open stateid and open seqid */
                status = nfs4_preprocess_confirmed_seqid_op(cstate,
                                        lock->lk_new_open_seqid,
                                        &lock->lk_new_open_stateid,
                                        &open_stp, nn);
                if (status)
                        goto out;
                open_sop = openowner(open_stp->st_stateowner);
                status = nfserr_bad_stateid;
                if (!same_clid(&open_sop->oo_owner.so_client->cl_clientid,
                                                &lock->v.new.clientid))
                        goto out;
                status = lookup_or_create_lock_state(cstate, open_stp, lock,
                                                        &lock_stp, &new);
        } else {
                status = nfs4_preprocess_seqid_op(cstate,
                                       lock->lk_old_lock_seqid,
                                       &lock->lk_old_lock_stateid,
                                       NFS4_LOCK_STID, &lock_stp, nn);
        }
        if (status)
                goto out;
        lock_sop = lockowner(lock_stp->st_stateowner);

        lkflg = setlkflg(lock->lk_type);
        status = nfs4_check_openmode(lock_stp, lkflg);
        if (status)
                goto out;

        status = nfserr_grace;
        if (locks_in_grace(net) && !lock->lk_reclaim)
                goto out;
        status = nfserr_no_grace;
        if (!locks_in_grace(net) && lock->lk_reclaim)
                goto out;

        file_lock = locks_alloc_lock();
        if (!file_lock) {
                dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
                status = nfserr_jukebox;
                goto out;
        }

        fp = lock_stp->st_stid.sc_file;
        switch (lock->lk_type) {
                case NFS4_READ_LT:
                case NFS4_READW_LT:
                        spin_lock(&fp->fi_lock);
                        filp = find_readable_file_locked(fp);
                        if (filp)
                                get_lock_access(lock_stp, NFS4_SHARE_ACCESS_READ);
                        spin_unlock(&fp->fi_lock);
                        file_lock->fl_type = F_RDLCK;
                        break;
                case NFS4_WRITE_LT:
                case NFS4_WRITEW_LT:
                        spin_lock(&fp->fi_lock);
                        filp = find_writeable_file_locked(fp);
                        if (filp)
                                get_lock_access(lock_stp, NFS4_SHARE_ACCESS_WRITE);
                        spin_unlock(&fp->fi_lock);
                        file_lock->fl_type = F_WRLCK;
                        break;
                default:
                        status = nfserr_inval;
                goto out;
        }
        if (!filp) {
                status = nfserr_openmode;
                goto out;
        }
        file_lock->fl_owner = (fl_owner_t)lock_sop;
        file_lock->fl_pid = current->tgid;
        file_lock->fl_file = filp;
        file_lock->fl_flags = FL_POSIX;
        file_lock->fl_lmops = &nfsd_posix_mng_ops;
        file_lock->fl_start = lock->lk_offset;
        file_lock->fl_end = last_byte_offset(lock->lk_offset, lock->lk_length);
        nfs4_transform_lock_offset(file_lock);

        conflock = locks_alloc_lock();
        if (!conflock) {
                dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
                status = nfserr_jukebox;
                goto out;
        }

        err = vfs_lock_file(filp, F_SETLK, file_lock, conflock);
        switch (-err) {
        case 0: /* success! */
                update_stateid(&lock_stp->st_stid.sc_stateid);
                memcpy(&lock->lk_resp_stateid, &lock_stp->st_stid.sc_stateid, 
                                sizeof(stateid_t));
                status = 0;
                break;
        case (EAGAIN):          /* conflock holds conflicting lock */
                status = nfserr_denied;
                dprintk("NFSD: nfsd4_lock: conflicting lock found!\n");
                nfs4_set_lock_denied(conflock, &lock->lk_denied);
                break;
        case (EDEADLK):
                status = nfserr_deadlock;
                break;
        default:
                dprintk("NFSD: nfsd4_lock: vfs_lock_file() failed! status %d\n",err);
                status = nfserrno(err);
                break;
        }
out:
        if (filp)
                fput(filp);
        if (lock_stp) {
                /* Bump seqid manually if the 4.0 replay owner is openowner */
                if (cstate->replay_owner &&
                    cstate->replay_owner != &lock_sop->lo_owner &&
                    seqid_mutating_err(ntohl(status)))
                        lock_sop->lo_owner.so_seqid++;

                /*
                 * If this is a new, never-before-used stateid, and we are
                 * returning an error, then just go ahead and release it.
                 */
                if (status && new)
                        release_lock_stateid(lock_stp);

                nfs4_put_stid(&lock_stp->st_stid);
        }
        if (open_stp)
                nfs4_put_stid(&open_stp->st_stid);
        nfsd4_bump_seqid(cstate, status);
        if (file_lock)
                locks_free_lock(file_lock);
        if (conflock)
                locks_free_lock(conflock);
        return status;
}

/*
 * The NFSv4 spec allows a client to do a LOCKT without holding an OPEN,
 * so we do a temporary open here just to get an open file to pass to
 * vfs_test_lock.  (Arguably perhaps test_lock should be done with an
 * inode operation.)
 */
static __be32 nfsd_test_lock(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file_lock *lock)
{
        struct file *file;
        __be32 err = nfsd_open(rqstp, fhp, S_IFREG, NFSD_MAY_READ, &file);
        if (!err) {
                err = nfserrno(vfs_test_lock(file, lock));
                nfsd_close(file);
        }
        return err;
}

/*
 * LOCKT operation
 */
__be32
nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
            struct nfsd4_lockt *lockt)
{
        struct file_lock *file_lock = NULL;
        struct nfs4_lockowner *lo = NULL;
        __be32 status;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        if (locks_in_grace(SVC_NET(rqstp)))
                return nfserr_grace;

        if (check_lock_length(lockt->lt_offset, lockt->lt_length))
                 return nfserr_inval;

        if (!nfsd4_has_session(cstate)) {
                status = lookup_clientid(&lockt->lt_clientid, cstate, nn);
                if (status)
                        goto out;
        }

        if ((status = fh_verify(rqstp, &cstate->current_fh, S_IFREG, 0)))
                goto out;

        file_lock = locks_alloc_lock();
        if (!file_lock) {
                dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
                status = nfserr_jukebox;
                goto out;
        }

        switch (lockt->lt_type) {
                case NFS4_READ_LT:
                case NFS4_READW_LT:
                        file_lock->fl_type = F_RDLCK;
                break;
                case NFS4_WRITE_LT:
                case NFS4_WRITEW_LT:
                        file_lock->fl_type = F_WRLCK;
                break;
                default:
                        dprintk("NFSD: nfs4_lockt: bad lock type!\n");
                        status = nfserr_inval;
                goto out;
        }

        lo = find_lockowner_str(&lockt->lt_clientid, &lockt->lt_owner,
                                cstate->clp);
        if (lo)
                file_lock->fl_owner = (fl_owner_t)lo;
        file_lock->fl_pid = current->tgid;
        file_lock->fl_flags = FL_POSIX;

        file_lock->fl_start = lockt->lt_offset;
        file_lock->fl_end = last_byte_offset(lockt->lt_offset, lockt->lt_length);

        nfs4_transform_lock_offset(file_lock);

        status = nfsd_test_lock(rqstp, &cstate->current_fh, file_lock);
        if (status)
                goto out;

        if (file_lock->fl_type != F_UNLCK) {
                status = nfserr_denied;
                nfs4_set_lock_denied(file_lock, &lockt->lt_denied);
        }
out:
        if (lo)
                nfs4_put_stateowner(&lo->lo_owner);
        if (file_lock)
                locks_free_lock(file_lock);
        return status;
}

__be32
nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
            struct nfsd4_locku *locku)
{
        struct nfs4_ol_stateid *stp;
        struct file *filp = NULL;
        struct file_lock *file_lock = NULL;
        __be32 status;
        int err;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        dprintk("NFSD: nfsd4_locku: start=%Ld length=%Ld\n",
                (long long) locku->lu_offset,
                (long long) locku->lu_length);

        if (check_lock_length(locku->lu_offset, locku->lu_length))
                 return nfserr_inval;

        status = nfs4_preprocess_seqid_op(cstate, locku->lu_seqid,
                                        &locku->lu_stateid, NFS4_LOCK_STID,
                                        &stp, nn);
        if (status)
                goto out;
        filp = find_any_file(stp->st_stid.sc_file);
        if (!filp) {
                status = nfserr_lock_range;
                goto put_stateid;
        }
        file_lock = locks_alloc_lock();
        if (!file_lock) {
                dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
                status = nfserr_jukebox;
                goto fput;
        }

        file_lock->fl_type = F_UNLCK;
        file_lock->fl_owner = (fl_owner_t)lockowner(stp->st_stateowner);
        file_lock->fl_pid = current->tgid;
        file_lock->fl_file = filp;
        file_lock->fl_flags = FL_POSIX;
        file_lock->fl_lmops = &nfsd_posix_mng_ops;
        file_lock->fl_start = locku->lu_offset;

        file_lock->fl_end = last_byte_offset(locku->lu_offset,
                                                locku->lu_length);
        nfs4_transform_lock_offset(file_lock);

        err = vfs_lock_file(filp, F_SETLK, file_lock, NULL);
        if (err) {
                dprintk("NFSD: nfs4_locku: vfs_lock_file failed!\n");
                goto out_nfserr;
        }
        update_stateid(&stp->st_stid.sc_stateid);
        memcpy(&locku->lu_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));
fput:
        fput(filp);
put_stateid:
        nfs4_put_stid(&stp->st_stid);
out:
        nfsd4_bump_seqid(cstate, status);
        if (file_lock)
                locks_free_lock(file_lock);
        return status;

out_nfserr:
        status = nfserrno(err);
        goto fput;
}

/*
 * returns
 *      true:  locks held by lockowner
 *      false: no locks held by lockowner
 */
static bool
check_for_locks(struct nfs4_file *fp, struct nfs4_lockowner *lowner)
{
        struct file_lock **flpp;
        int status = false;
        struct file *filp = find_any_file(fp);
        struct inode *inode;

        if (!filp) {
                /* Any valid lock stateid should have some sort of access */
                WARN_ON_ONCE(1);
                return status;
        }

        inode = file_inode(filp);

        spin_lock(&inode->i_lock);
        for (flpp = &inode->i_flock; *flpp != NULL; flpp = &(*flpp)->fl_next) {
                if ((*flpp)->fl_owner == (fl_owner_t)lowner) {
                        status = true;
                        break;
                }
        }
        spin_unlock(&inode->i_lock);
        fput(filp);
        return status;
}

__be32
nfsd4_release_lockowner(struct svc_rqst *rqstp,
                        struct nfsd4_compound_state *cstate,
                        struct nfsd4_release_lockowner *rlockowner)
{
        clientid_t *clid = &rlockowner->rl_clientid;
        struct nfs4_stateowner *sop;
        struct nfs4_lockowner *lo = NULL;
        struct nfs4_ol_stateid *stp;
        struct xdr_netobj *owner = &rlockowner->rl_owner;
        unsigned int hashval = ownerstr_hashval(owner);
        __be32 status;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
        struct nfs4_client *clp;

        dprintk("nfsd4_release_lockowner clientid: (%08x/%08x):\n",
                clid->cl_boot, clid->cl_id);

        status = lookup_clientid(clid, cstate, nn);
        if (status)
                return status;

        clp = cstate->clp;
        /* Find the matching lock stateowner */
        spin_lock(&clp->cl_lock);
        list_for_each_entry(sop, &clp->cl_ownerstr_hashtbl[hashval],
                            so_strhash) {

                if (sop->so_is_open_owner || !same_owner_str(sop, owner))
                        continue;

                /* see if there are still any locks associated with it */
                lo = lockowner(sop);
                list_for_each_entry(stp, &sop->so_stateids, st_perstateowner) {
                        if (check_for_locks(stp->st_stid.sc_file, lo)) {
                                status = nfserr_locks_held;
                                spin_unlock(&clp->cl_lock);
                                return status;
                        }
                }

                atomic_inc(&sop->so_count);
                break;
        }
        spin_unlock(&clp->cl_lock);
        if (lo)
                release_lockowner(lo);
        return status;
}

static inline struct nfs4_client_reclaim *
alloc_reclaim(void)
{
        return kmalloc(sizeof(struct nfs4_client_reclaim), GFP_KERNEL);
}

bool
nfs4_has_reclaimed_state(const char *name, struct nfsd_net *nn)
{
        struct nfs4_client_reclaim *crp;

        crp = nfsd4_find_reclaim_client(name, nn);
        return (crp && crp->cr_clp);
}

/*
 * failure => all reset bets are off, nfserr_no_grace...
 */
struct nfs4_client_reclaim *
nfs4_client_to_reclaim(const char *name, struct nfsd_net *nn)
{
        unsigned int strhashval;
        struct nfs4_client_reclaim *crp;

        dprintk("NFSD nfs4_client_to_reclaim NAME: %.*s\n", HEXDIR_LEN, name);
        crp = alloc_reclaim();
        if (crp) {
                strhashval = clientstr_hashval(name);
                INIT_LIST_HEAD(&crp->cr_strhash);
                list_add(&crp->cr_strhash, &nn->reclaim_str_hashtbl[strhashval]);
                memcpy(crp->cr_recdir, name, HEXDIR_LEN);
                crp->cr_clp = NULL;
                nn->reclaim_str_hashtbl_size++;
        }
        return crp;
}

void
nfs4_remove_reclaim_record(struct nfs4_client_reclaim *crp, struct nfsd_net *nn)
{
        list_del(&crp->cr_strhash);
        kfree(crp);
        nn->reclaim_str_hashtbl_size--;
}

void
nfs4_release_reclaim(struct nfsd_net *nn)
{
        struct nfs4_client_reclaim *crp = NULL;
        int i;

        for (i = 0; i < CLIENT_HASH_SIZE; i++) {
                while (!list_empty(&nn->reclaim_str_hashtbl[i])) {
                        crp = list_entry(nn->reclaim_str_hashtbl[i].next,
                                        struct nfs4_client_reclaim, cr_strhash);
                        nfs4_remove_reclaim_record(crp, nn);
                }
        }
        WARN_ON_ONCE(nn->reclaim_str_hashtbl_size);
}

/*
 * called from OPEN, CLAIM_PREVIOUS with a new clientid. */
struct nfs4_client_reclaim *
nfsd4_find_reclaim_client(const char *recdir, struct nfsd_net *nn)
{
        unsigned int strhashval;
        struct nfs4_client_reclaim *crp = NULL;

        dprintk("NFSD: nfs4_find_reclaim_client for recdir %s\n", recdir);

        strhashval = clientstr_hashval(recdir);
        list_for_each_entry(crp, &nn->reclaim_str_hashtbl[strhashval], cr_strhash) {
                if (same_name(crp->cr_recdir, recdir)) {
                        return crp;
                }
        }
        return NULL;
}

/*
* Called from OPEN. Look for clientid in reclaim list.
*/
__be32
nfs4_check_open_reclaim(clientid_t *clid,
                struct nfsd4_compound_state *cstate,
                struct nfsd_net *nn)
{
        __be32 status;

        /* find clientid in conf_id_hashtbl */
        status = lookup_clientid(clid, cstate, nn);
        if (status)
                return nfserr_reclaim_bad;

        if (nfsd4_client_record_check(cstate->clp))
                return nfserr_reclaim_bad;

        return nfs_ok;
}

#ifdef CONFIG_NFSD_FAULT_INJECTION
static inline void
put_client(struct nfs4_client *clp)
{
        atomic_dec(&clp->cl_refcount);
}

static struct nfs4_client *
nfsd_find_client(struct sockaddr_storage *addr, size_t addr_size)
{
        struct nfs4_client *clp;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                          nfsd_net_id);

        if (!nfsd_netns_ready(nn))
                return NULL;

        list_for_each_entry(clp, &nn->client_lru, cl_lru) {
                if (memcmp(&clp->cl_addr, addr, addr_size) == 0)
                        return clp;
        }
        return NULL;
}

u64
nfsd_inject_print_clients(void)
{
        struct nfs4_client *clp;
        u64 count = 0;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                          nfsd_net_id);
        char buf[INET6_ADDRSTRLEN];

        if (!nfsd_netns_ready(nn))
                return 0;

        spin_lock(&nn->client_lock);
        list_for_each_entry(clp, &nn->client_lru, cl_lru) {
                rpc_ntop((struct sockaddr *)&clp->cl_addr, buf, sizeof(buf));
                pr_info("NFS Client: %s\n", buf);
                ++count;
        }
        spin_unlock(&nn->client_lock);

        return count;
}

u64
nfsd_inject_forget_client(struct sockaddr_storage *addr, size_t addr_size)
{
        u64 count = 0;
        struct nfs4_client *clp;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                          nfsd_net_id);

        if (!nfsd_netns_ready(nn))
                return count;

        spin_lock(&nn->client_lock);
        clp = nfsd_find_client(addr, addr_size);
        if (clp) {
                if (mark_client_expired_locked(clp) == nfs_ok)
                        ++count;
                else
                        clp = NULL;
        }
        spin_unlock(&nn->client_lock);

        if (clp)
                expire_client(clp);

        return count;
}

u64
nfsd_inject_forget_clients(u64 max)
{
        u64 count = 0;
        struct nfs4_client *clp, *next;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);
        LIST_HEAD(reaplist);

        if (!nfsd_netns_ready(nn))
                return count;

        spin_lock(&nn->client_lock);
        list_for_each_entry_safe(clp, next, &nn->client_lru, cl_lru) {
                if (mark_client_expired_locked(clp) == nfs_ok) {
                        list_add(&clp->cl_lru, &reaplist);
                        if (max != 0 && ++count >= max)
                                break;
                }
        }
        spin_unlock(&nn->client_lock);

        list_for_each_entry_safe(clp, next, &reaplist, cl_lru)
                expire_client(clp);

        return count;
}

static void nfsd_print_count(struct nfs4_client *clp, unsigned int count,
                             const char *type)
{
        char buf[INET6_ADDRSTRLEN];
        rpc_ntop((struct sockaddr *)&clp->cl_addr, buf, sizeof(buf));
        printk(KERN_INFO "NFS Client: %s has %u %s\n", buf, count, type);
}

static void
nfsd_inject_add_lock_to_list(struct nfs4_ol_stateid *lst,
                             struct list_head *collect)
{
        struct nfs4_client *clp = lst->st_stid.sc_client;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                          nfsd_net_id);

        if (!collect)
                return;

        lockdep_assert_held(&nn->client_lock);
        atomic_inc(&clp->cl_refcount);
        list_add(&lst->st_locks, collect);
}

static u64 nfsd_foreach_client_lock(struct nfs4_client *clp, u64 max,
                                    struct list_head *collect,
                                    void (*func)(struct nfs4_ol_stateid *))
{
        struct nfs4_openowner *oop;
        struct nfs4_ol_stateid *stp, *st_next;
        struct nfs4_ol_stateid *lst, *lst_next;
        u64 count = 0;

        spin_lock(&clp->cl_lock);
        list_for_each_entry(oop, &clp->cl_openowners, oo_perclient) {
                list_for_each_entry_safe(stp, st_next,
                                &oop->oo_owner.so_stateids, st_perstateowner) {
                        list_for_each_entry_safe(lst, lst_next,
                                        &stp->st_locks, st_locks) {
                                if (func) {
                                        func(lst);
                                        nfsd_inject_add_lock_to_list(lst,
                                                                collect);
                                }
                                ++count;
                                /*
                                 * Despite the fact that these functions deal
                                 * with 64-bit integers for "count", we must
                                 * ensure that it doesn't blow up the
                                 * clp->cl_refcount. Throw a warning if we
                                 * start to approach INT_MAX here.
                                 */
                                WARN_ON_ONCE(count == (INT_MAX / 2));
                                if (count == max)
                                        goto out;
                        }
                }
        }
out:
        spin_unlock(&clp->cl_lock);

        return count;
}

static u64
nfsd_collect_client_locks(struct nfs4_client *clp, struct list_head *collect,
                          u64 max)
{
        return nfsd_foreach_client_lock(clp, max, collect, unhash_lock_stateid);
}

static u64
nfsd_print_client_locks(struct nfs4_client *clp)
{
        u64 count = nfsd_foreach_client_lock(clp, 0, NULL, NULL);
        nfsd_print_count(clp, count, "locked files");
        return count;
}

u64
nfsd_inject_print_locks(void)
{
        struct nfs4_client *clp;
        u64 count = 0;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);

        if (!nfsd_netns_ready(nn))
                return 0;

        spin_lock(&nn->client_lock);
        list_for_each_entry(clp, &nn->client_lru, cl_lru)
                count += nfsd_print_client_locks(clp);
        spin_unlock(&nn->client_lock);

        return count;
}

static void
nfsd_reap_locks(struct list_head *reaplist)
{
        struct nfs4_client *clp;
        struct nfs4_ol_stateid *stp, *next;

        list_for_each_entry_safe(stp, next, reaplist, st_locks) {
                list_del_init(&stp->st_locks);
                clp = stp->st_stid.sc_client;
                nfs4_put_stid(&stp->st_stid);
                put_client(clp);
        }
}

u64
nfsd_inject_forget_client_locks(struct sockaddr_storage *addr, size_t addr_size)
{
        unsigned int count = 0;
        struct nfs4_client *clp;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);
        LIST_HEAD(reaplist);

        if (!nfsd_netns_ready(nn))
                return count;

        spin_lock(&nn->client_lock);
        clp = nfsd_find_client(addr, addr_size);
        if (clp)
                count = nfsd_collect_client_locks(clp, &reaplist, 0);
        spin_unlock(&nn->client_lock);
        nfsd_reap_locks(&reaplist);
        return count;
}

u64
nfsd_inject_forget_locks(u64 max)
{
        u64 count = 0;
        struct nfs4_client *clp;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);
        LIST_HEAD(reaplist);

        if (!nfsd_netns_ready(nn))
                return count;

        spin_lock(&nn->client_lock);
        list_for_each_entry(clp, &nn->client_lru, cl_lru) {
                count += nfsd_collect_client_locks(clp, &reaplist, max - count);
                if (max != 0 && count >= max)
                        break;
        }
        spin_unlock(&nn->client_lock);
        nfsd_reap_locks(&reaplist);
        return count;
}

static u64
nfsd_foreach_client_openowner(struct nfs4_client *clp, u64 max,
                              struct list_head *collect,
                              void (*func)(struct nfs4_openowner *))
{
        struct nfs4_openowner *oop, *next;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);
        u64 count = 0;

        lockdep_assert_held(&nn->client_lock);

        spin_lock(&clp->cl_lock);
        list_for_each_entry_safe(oop, next, &clp->cl_openowners, oo_perclient) {
                if (func) {
                        func(oop);
                        if (collect) {
                                atomic_inc(&clp->cl_refcount);
                                list_add(&oop->oo_perclient, collect);
                        }
                }
                ++count;
                /*
                 * Despite the fact that these functions deal with
                 * 64-bit integers for "count", we must ensure that
                 * it doesn't blow up the clp->cl_refcount. Throw a
                 * warning if we start to approach INT_MAX here.
                 */
                WARN_ON_ONCE(count == (INT_MAX / 2));
                if (count == max)
                        break;
        }
        spin_unlock(&clp->cl_lock);

        return count;
}

static u64
nfsd_print_client_openowners(struct nfs4_client *clp)
{
        u64 count = nfsd_foreach_client_openowner(clp, 0, NULL, NULL);

        nfsd_print_count(clp, count, "openowners");
        return count;
}

static u64
nfsd_collect_client_openowners(struct nfs4_client *clp,
                               struct list_head *collect, u64 max)
{
        return nfsd_foreach_client_openowner(clp, max, collect,
                                                unhash_openowner_locked);
}

u64
nfsd_inject_print_openowners(void)
{
        struct nfs4_client *clp;
        u64 count = 0;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);

        if (!nfsd_netns_ready(nn))
                return 0;

        spin_lock(&nn->client_lock);
        list_for_each_entry(clp, &nn->client_lru, cl_lru)
                count += nfsd_print_client_openowners(clp);
        spin_unlock(&nn->client_lock);

        return count;
}

static void
nfsd_reap_openowners(struct list_head *reaplist)
{
        struct nfs4_client *clp;
        struct nfs4_openowner *oop, *next;

        list_for_each_entry_safe(oop, next, reaplist, oo_perclient) {
                list_del_init(&oop->oo_perclient);
                clp = oop->oo_owner.so_client;
                release_openowner(oop);
                put_client(clp);
        }
}

u64
nfsd_inject_forget_client_openowners(struct sockaddr_storage *addr,
                                     size_t addr_size)
{
        unsigned int count = 0;
        struct nfs4_client *clp;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);
        LIST_HEAD(reaplist);

        if (!nfsd_netns_ready(nn))
                return count;

        spin_lock(&nn->client_lock);
        clp = nfsd_find_client(addr, addr_size);
        if (clp)
                count = nfsd_collect_client_openowners(clp, &reaplist, 0);
        spin_unlock(&nn->client_lock);
        nfsd_reap_openowners(&reaplist);
        return count;
}

u64
nfsd_inject_forget_openowners(u64 max)
{
        u64 count = 0;
        struct nfs4_client *clp;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);
        LIST_HEAD(reaplist);

        if (!nfsd_netns_ready(nn))
                return count;

        spin_lock(&nn->client_lock);
        list_for_each_entry(clp, &nn->client_lru, cl_lru) {
                count += nfsd_collect_client_openowners(clp, &reaplist,
                                                        max - count);
                if (max != 0 && count >= max)
                        break;
        }
        spin_unlock(&nn->client_lock);
        nfsd_reap_openowners(&reaplist);
        return count;
}

static u64 nfsd_find_all_delegations(struct nfs4_client *clp, u64 max,
                                     struct list_head *victims)
{
        struct nfs4_delegation *dp, *next;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);
        u64 count = 0;

        lockdep_assert_held(&nn->client_lock);

        spin_lock(&state_lock);
        list_for_each_entry_safe(dp, next, &clp->cl_delegations, dl_perclnt) {
                if (victims) {
                        /*
                         * It's not safe to mess with delegations that have a
                         * non-zero dl_time. They might have already been broken
                         * and could be processed by the laundromat outside of
                         * the state_lock. Just leave them be.
                         */
                        if (dp->dl_time != 0)
                                continue;

                        atomic_inc(&clp->cl_refcount);
                        unhash_delegation_locked(dp);
                        list_add(&dp->dl_recall_lru, victims);
                }
                ++count;
                /*
                 * Despite the fact that these functions deal with
                 * 64-bit integers for "count", we must ensure that
                 * it doesn't blow up the clp->cl_refcount. Throw a
                 * warning if we start to approach INT_MAX here.
                 */
                WARN_ON_ONCE(count == (INT_MAX / 2));
                if (count == max)
                        break;
        }
        spin_unlock(&state_lock);
        return count;
}

static u64
nfsd_print_client_delegations(struct nfs4_client *clp)
{
        u64 count = nfsd_find_all_delegations(clp, 0, NULL);

        nfsd_print_count(clp, count, "delegations");
        return count;
}

u64
nfsd_inject_print_delegations(void)
{
        struct nfs4_client *clp;
        u64 count = 0;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);

        if (!nfsd_netns_ready(nn))
                return 0;

        spin_lock(&nn->client_lock);
        list_for_each_entry(clp, &nn->client_lru, cl_lru)
                count += nfsd_print_client_delegations(clp);
        spin_unlock(&nn->client_lock);

        return count;
}

static void
nfsd_forget_delegations(struct list_head *reaplist)
{
        struct nfs4_client *clp;
        struct nfs4_delegation *dp, *next;

        list_for_each_entry_safe(dp, next, reaplist, dl_recall_lru) {
                list_del_init(&dp->dl_recall_lru);
                clp = dp->dl_stid.sc_client;
                revoke_delegation(dp);
                put_client(clp);
        }
}

u64
nfsd_inject_forget_client_delegations(struct sockaddr_storage *addr,
                                      size_t addr_size)
{
        u64 count = 0;
        struct nfs4_client *clp;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);
        LIST_HEAD(reaplist);

        if (!nfsd_netns_ready(nn))
                return count;

        spin_lock(&nn->client_lock);
        clp = nfsd_find_client(addr, addr_size);
        if (clp)
                count = nfsd_find_all_delegations(clp, 0, &reaplist);
        spin_unlock(&nn->client_lock);

        nfsd_forget_delegations(&reaplist);
        return count;
}

u64
nfsd_inject_forget_delegations(u64 max)
{
        u64 count = 0;
        struct nfs4_client *clp;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);
        LIST_HEAD(reaplist);

        if (!nfsd_netns_ready(nn))
                return count;

        spin_lock(&nn->client_lock);
        list_for_each_entry(clp, &nn->client_lru, cl_lru) {
                count += nfsd_find_all_delegations(clp, max - count, &reaplist);
                if (max != 0 && count >= max)
                        break;
        }
        spin_unlock(&nn->client_lock);
        nfsd_forget_delegations(&reaplist);
        return count;
}

static void
nfsd_recall_delegations(struct list_head *reaplist)
{
        struct nfs4_client *clp;
        struct nfs4_delegation *dp, *next;

        list_for_each_entry_safe(dp, next, reaplist, dl_recall_lru) {
                list_del_init(&dp->dl_recall_lru);
                clp = dp->dl_stid.sc_client;
                /*
                 * We skipped all entries that had a zero dl_time before,
                 * so we can now reset the dl_time back to 0. If a delegation
                 * break comes in now, then it won't make any difference since
                 * we're recalling it either way.
                 */
                spin_lock(&state_lock);
                dp->dl_time = 0;
                spin_unlock(&state_lock);
                nfsd_break_one_deleg(dp);
                put_client(clp);
        }
}

u64
nfsd_inject_recall_client_delegations(struct sockaddr_storage *addr,
                                      size_t addr_size)
{
        u64 count = 0;
        struct nfs4_client *clp;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);
        LIST_HEAD(reaplist);

        if (!nfsd_netns_ready(nn))
                return count;

        spin_lock(&nn->client_lock);
        clp = nfsd_find_client(addr, addr_size);
        if (clp)
                count = nfsd_find_all_delegations(clp, 0, &reaplist);
        spin_unlock(&nn->client_lock);

        nfsd_recall_delegations(&reaplist);
        return count;
}

u64
nfsd_inject_recall_delegations(u64 max)
{
        u64 count = 0;
        struct nfs4_client *clp, *next;
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                nfsd_net_id);
        LIST_HEAD(reaplist);

        if (!nfsd_netns_ready(nn))
                return count;

        spin_lock(&nn->client_lock);
        list_for_each_entry_safe(clp, next, &nn->client_lru, cl_lru) {
                count += nfsd_find_all_delegations(clp, max - count, &reaplist);
                if (max != 0 && ++count >= max)
                        break;
        }
        spin_unlock(&nn->client_lock);
        nfsd_recall_delegations(&reaplist);
        return count;
}
#endif /* CONFIG_NFSD_FAULT_INJECTION */

/*
 * Since the lifetime of a delegation isn't limited to that of an open, a
 * client may quite reasonably hang on to a delegation as long as it has
 * the inode cached.  This becomes an obvious problem the first time a
 * client's inode cache approaches the size of the server's total memory.
 *
 * For now we avoid this problem by imposing a hard limit on the number
 * of delegations, which varies according to the server's memory size.
 */
static void
set_max_delegations(void)
{
        /*
         * Allow at most 4 delegations per megabyte of RAM.  Quick
         * estimates suggest that in the worst case (where every delegation
         * is for a different inode), a delegation could take about 1.5K,
         * giving a worst case usage of about 6% of memory.
         */
        max_delegations = nr_free_buffer_pages() >> (20 - 2 - PAGE_SHIFT);
}

static int nfs4_state_create_net(struct net *net)
{
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);
        int i;

        nn->conf_id_hashtbl = kmalloc(sizeof(struct list_head) *
                        CLIENT_HASH_SIZE, GFP_KERNEL);
        if (!nn->conf_id_hashtbl)
                goto err;
        nn->unconf_id_hashtbl = kmalloc(sizeof(struct list_head) *
                        CLIENT_HASH_SIZE, GFP_KERNEL);
        if (!nn->unconf_id_hashtbl)
                goto err_unconf_id;
        nn->sessionid_hashtbl = kmalloc(sizeof(struct list_head) *
                        SESSION_HASH_SIZE, GFP_KERNEL);
        if (!nn->sessionid_hashtbl)
                goto err_sessionid;

        for (i = 0; i < CLIENT_HASH_SIZE; i++) {
                INIT_LIST_HEAD(&nn->conf_id_hashtbl[i]);
                INIT_LIST_HEAD(&nn->unconf_id_hashtbl[i]);
        }
        for (i = 0; i < SESSION_HASH_SIZE; i++)
                INIT_LIST_HEAD(&nn->sessionid_hashtbl[i]);
        nn->conf_name_tree = RB_ROOT;
        nn->unconf_name_tree = RB_ROOT;
        INIT_LIST_HEAD(&nn->client_lru);
        INIT_LIST_HEAD(&nn->close_lru);
        INIT_LIST_HEAD(&nn->del_recall_lru);
        spin_lock_init(&nn->client_lock);

        INIT_DELAYED_WORK(&nn->laundromat_work, laundromat_main);
        get_net(net);

        return 0;

err_sessionid:
        kfree(nn->unconf_id_hashtbl);
err_unconf_id:
        kfree(nn->conf_id_hashtbl);
err:
        return -ENOMEM;
}

static void
nfs4_state_destroy_net(struct net *net)
{
        int i;
        struct nfs4_client *clp = NULL;
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        for (i = 0; i < CLIENT_HASH_SIZE; i++) {
                while (!list_empty(&nn->conf_id_hashtbl[i])) {
                        clp = list_entry(nn->conf_id_hashtbl[i].next, struct nfs4_client, cl_idhash);
                        destroy_client(clp);
                }
        }

        for (i = 0; i < CLIENT_HASH_SIZE; i++) {
                while (!list_empty(&nn->unconf_id_hashtbl[i])) {
                        clp = list_entry(nn->unconf_id_hashtbl[i].next, struct nfs4_client, cl_idhash);
                        destroy_client(clp);
                }
        }

        kfree(nn->sessionid_hashtbl);
        kfree(nn->unconf_id_hashtbl);
        kfree(nn->conf_id_hashtbl);
        put_net(net);
}

int
nfs4_state_start_net(struct net *net)
{
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);
        int ret;

        ret = nfs4_state_create_net(net);
        if (ret)
                return ret;
        nfsd4_client_tracking_init(net);
        nn->boot_time = get_seconds();
        locks_start_grace(net, &nn->nfsd4_manager);
        nn->grace_ended = false;
        printk(KERN_INFO "NFSD: starting %ld-second grace period (net %p)\n",
               nn->nfsd4_grace, net);
        queue_delayed_work(laundry_wq, &nn->laundromat_work, nn->nfsd4_grace * HZ);
        return 0;
}

/* initialization to perform when the nfsd service is started: */

int
nfs4_state_start(void)
{
        int ret;

        ret = set_callback_cred();
        if (ret)
                return -ENOMEM;
        laundry_wq = create_singlethread_workqueue("nfsd4");
        if (laundry_wq == NULL) {
                ret = -ENOMEM;
                goto out_recovery;
        }
        ret = nfsd4_create_callback_queue();
        if (ret)
                goto out_free_laundry;

        set_max_delegations();

        return 0;

out_free_laundry:
        destroy_workqueue(laundry_wq);
out_recovery:
        return ret;
}

void
nfs4_state_shutdown_net(struct net *net)
{
        struct nfs4_delegation *dp = NULL;
        struct list_head *pos, *next, reaplist;
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        cancel_delayed_work_sync(&nn->laundromat_work);
        locks_end_grace(&nn->nfsd4_manager);

        INIT_LIST_HEAD(&reaplist);
        spin_lock(&state_lock);
        list_for_each_safe(pos, next, &nn->del_recall_lru) {
                dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
                unhash_delegation_locked(dp);
                list_add(&dp->dl_recall_lru, &reaplist);
        }
        spin_unlock(&state_lock);
        list_for_each_safe(pos, next, &reaplist) {
                dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
                list_del_init(&dp->dl_recall_lru);
                nfs4_put_deleg_lease(dp->dl_stid.sc_file);
                nfs4_put_stid(&dp->dl_stid);
        }

        nfsd4_client_tracking_exit(net);
        nfs4_state_destroy_net(net);
}

void
nfs4_state_shutdown(void)
{
        destroy_workqueue(laundry_wq);
        nfsd4_destroy_callback_queue();
}

static void
get_stateid(struct nfsd4_compound_state *cstate, stateid_t *stateid)
{
        if (HAS_STATE_ID(cstate, CURRENT_STATE_ID_FLAG) && CURRENT_STATEID(stateid))
                memcpy(stateid, &cstate->current_stateid, sizeof(stateid_t));
}

static void
put_stateid(struct nfsd4_compound_state *cstate, stateid_t *stateid)
{
        if (cstate->minorversion) {
                memcpy(&cstate->current_stateid, stateid, sizeof(stateid_t));
                SET_STATE_ID(cstate, CURRENT_STATE_ID_FLAG);
        }
}

void
clear_current_stateid(struct nfsd4_compound_state *cstate)
{
        CLEAR_STATE_ID(cstate, CURRENT_STATE_ID_FLAG);
}

/*
 * functions to set current state id
 */
void
nfsd4_set_opendowngradestateid(struct nfsd4_compound_state *cstate, struct nfsd4_open_downgrade *odp)
{
        put_stateid(cstate, &odp->od_stateid);
}

void
nfsd4_set_openstateid(struct nfsd4_compound_state *cstate, struct nfsd4_open *open)
{
        put_stateid(cstate, &open->op_stateid);
}

void
nfsd4_set_closestateid(struct nfsd4_compound_state *cstate, struct nfsd4_close *close)
{
        put_stateid(cstate, &close->cl_stateid);
}

void
nfsd4_set_lockstateid(struct nfsd4_compound_state *cstate, struct nfsd4_lock *lock)
{
        put_stateid(cstate, &lock->lk_resp_stateid);
}

/*
 * functions to consume current state id
 */

void
nfsd4_get_opendowngradestateid(struct nfsd4_compound_state *cstate, struct nfsd4_open_downgrade *odp)
{
        get_stateid(cstate, &odp->od_stateid);
}

void
nfsd4_get_delegreturnstateid(struct nfsd4_compound_state *cstate, struct nfsd4_delegreturn *drp)
{
        get_stateid(cstate, &drp->dr_stateid);
}

void
nfsd4_get_freestateid(struct nfsd4_compound_state *cstate, struct nfsd4_free_stateid *fsp)
{
        get_stateid(cstate, &fsp->fr_stateid);
}

void
nfsd4_get_setattrstateid(struct nfsd4_compound_state *cstate, struct nfsd4_setattr *setattr)
{
        get_stateid(cstate, &setattr->sa_stateid);
}

void
nfsd4_get_closestateid(struct nfsd4_compound_state *cstate, struct nfsd4_close *close)
{
        get_stateid(cstate, &close->cl_stateid);
}

void
nfsd4_get_lockustateid(struct nfsd4_compound_state *cstate, struct nfsd4_locku *locku)
{
        get_stateid(cstate, &locku->lu_stateid);
}

void
nfsd4_get_readstateid(struct nfsd4_compound_state *cstate, struct nfsd4_read *read)
{
        get_stateid(cstate, &read->rd_stateid);
}

void
nfsd4_get_writestateid(struct nfsd4_compound_state *cstate, struct nfsd4_write *write)
{
        get_stateid(cstate, &write->wr_stateid);
}