mm/page_alloc: free pages in a single pass during bulk free

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

/*
*  Copyright (c) 2001 The Regents of the University of Michigan.
*  All rights reserved.
*
*  Kendrick Smith <[email protected]>
*  Andy Adamson <[email protected]>
*
*  Redistribution and use in source and binary forms, with or without
*  modification, are permitted provided that the following conditions
*  are met:
*
*  1. Redistributions of source code must retain the above copyright
*     notice, this list of conditions and the following disclaimer.
*  2. Redistributions in binary form must reproduce the above copyright
*     notice, this list of conditions and the following disclaimer in the
*     documentation and/or other materials provided with the distribution.
*  3. Neither the name of the University nor the names of its
*     contributors may be used to endorse or promote products derived
*     from this software without specific prior written permission.
*
*  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
*  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
*  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
*  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
*  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
*  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
*  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
*  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
*  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
*  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
*  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/

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

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

#define NFSDDBG_FACILITY                NFSDDBG_PROC

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

static u64 current_sessionid = 1;

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

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

/* Locking: */

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

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

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

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

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

static void free_session(struct nfsd4_session *);

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

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

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

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

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

        lockdep_assert_held(&nn->client_lock);

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

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

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

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

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

        lockdep_assert_held(&nn->client_lock);

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

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

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

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

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

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

        lockdep_assert_held(&nn->client_lock);

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

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

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

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

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

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

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

static void
free_nbl(struct kref *kref)
{
        struct nfsd4_blocked_lock *nbl;

        nbl = container_of(kref, struct nfsd4_blocked_lock, nbl_kref);
        kfree(nbl);
}

static void
free_blocked_lock(struct nfsd4_blocked_lock *nbl)
{
        locks_delete_block(&nbl->nbl_lock);
        locks_release_private(&nbl->nbl_lock);
        kref_put(&nbl->nbl_kref, free_nbl);
}

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

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

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

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

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

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

        free_blocked_lock(nbl);
}

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

/*
 * 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 in
 * https://datatracker.ietf.org/doc/html/rfc7530#section-16.19.4 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.
 *
 * This enforcement is arguably 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.
 *
 * But you could also argue that our current code is already overkill,
 * since it only exists to return NFS4ERR_INVAL on incorrect client
 * behavior.
 */
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;
}

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

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

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

        lockdep_assert_held(&clp->cl_lock);

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

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

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

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

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

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

        kmem_cache_free(file_slab, fp);
}

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

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

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

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

        lockdep_assert_held(&f->fi_lock);

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

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

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

        return ret;
}

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

        lockdep_assert_held(&f->fi_lock);

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

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

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

        return ret;
}

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

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

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

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

static atomic_long_t num_delegations;
unsigned long max_delegations;

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

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

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

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

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

static unsigned int file_hashval(struct svc_fh *fh)
{
        struct inode *inode = d_inode(fh->fh_dentry);

        /* XXX: why not (here & in file cache) use inode? */
        return (unsigned int)hash_long(inode->i_ino, FILE_HASH_BITS);
}

static struct hlist_head file_hashtbl[FILE_HASH_SIZE];

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

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

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

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

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

        __nfs4_file_get_access(fp, access);
        return nfs_ok;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        if (!co)
                return;

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

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

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

        if (!new)
                return NULL;

        cl = new->co_client;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        return openlockstateid(stid);
}

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

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

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

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

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

        return 0;
}

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

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

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

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

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

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

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

        might_lock(&clp->cl_lock);

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

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

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

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

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

        if (nf)
                nfsd_file_put(nf);
}

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

        WARN_ON_ONCE(!fp->fi_delegees);

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

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

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

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

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

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

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

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

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

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

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

static bool delegation_hashed(struct nfs4_delegation *dp)
{
        return !(list_empty(&dp->dl_perfile));
}

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

        lockdep_assert_held(&state_lock);

        if (!delegation_hashed(dp))
                return false;

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

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

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

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

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

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

/* 
 * SETCLIENTID state 
 */

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

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

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

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

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

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

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

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

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

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

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

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

        might_lock(&clp->cl_lock);

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

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

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

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

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

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

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

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

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

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

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

        lockdep_assert_held(&clp->cl_lock);

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

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

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

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

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

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

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

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

        lockdep_assert_held(&clp->cl_lock);

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

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

        might_sleep();

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

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

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

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

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

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

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

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

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

        lockdep_assert_held(&clp->cl_lock);

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

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

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

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

        INIT_LIST_HEAD(&reaplist);

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

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

        return sid->sequence % SESSION_HASH_SIZE;
}

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

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

        if (nfserr == nfserr_replay_me)
                return;

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

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

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

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

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

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

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

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

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

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

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

        return num;
}

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

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

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

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

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

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

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

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

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

        trace_nfsd_cb_lost(clp);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        INIT_LIST_HEAD(&new->se_conns);

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

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

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

        lockdep_assert_held(&nn->client_lock);

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

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

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

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

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

        lockdep_assert_held(&nn->client_lock);

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

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

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

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

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

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

static void drop_client(struct nfs4_client *clp)
{
        kref_put(&clp->cl_nfsdfs.cl_ref, __free_client);
}

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

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

        lockdep_assert_held(&nn->client_lock);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


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

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

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

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

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

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

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

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

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

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

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

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

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

static void seq_quote_mem(struct seq_file *m, char *data, int len)
{
        seq_printf(m, "\"");
        seq_escape_mem(m, data, len, ESCAPE_HEX | ESCAPE_NAP | ESCAPE_APPEND, "\"\\");
        seq_printf(m, "\"");
}

static const char *cb_state2str(int state)
{
        switch (state) {
        case NFSD4_CB_UP:
                return "UP";
        case NFSD4_CB_UNKNOWN:
                return "UNKNOWN";
        case NFSD4_CB_DOWN:
                return "DOWN";
        case NFSD4_CB_FAULT:
                return "FAULT";
        }
        return "UNDEFINED";
}

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

        clp = get_nfsdfs_clp(inode);
        if (!clp)
                return -ENXIO;
        memcpy(&clid, &clp->cl_clientid, sizeof(clid));
        seq_printf(m, "clientid: 0x%llx\n", clid);
        seq_printf(m, "address: \"%pISpc\"\n", (struct sockaddr *)&clp->cl_addr);
        if (test_bit(NFSD4_CLIENT_CONFIRMED, &clp->cl_flags))
                seq_puts(m, "status: confirmed\n");
        else
                seq_puts(m, "status: unconfirmed\n");
        seq_printf(m, "name: ");
        seq_quote_mem(m, clp->cl_name.data, clp->cl_name.len);
        seq_printf(m, "\nminor version: %d\n", clp->cl_minorversion);
        if (clp->cl_nii_domain.data) {
                seq_printf(m, "Implementation domain: ");
                seq_quote_mem(m, clp->cl_nii_domain.data,
                                        clp->cl_nii_domain.len);
                seq_printf(m, "\nImplementation name: ");
                seq_quote_mem(m, clp->cl_nii_name.data, clp->cl_nii_name.len);
                seq_printf(m, "\nImplementation time: [%lld, %ld]\n",
                        clp->cl_nii_time.tv_sec, clp->cl_nii_time.tv_nsec);
        }
        seq_printf(m, "callback state: %s\n", cb_state2str(clp->cl_cb_state));
        seq_printf(m, "callback address: %pISpc\n", &clp->cl_cb_conn.cb_addr);
        drop_client(clp);

        return 0;
}

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

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

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

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

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

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

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

        spin_unlock(&clp->cl_lock);
}

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

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

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

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

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

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

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

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

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

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

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

        return 0;
}

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

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

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

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

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

        return 0;
}

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

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

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

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

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

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

        return 0;
}

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

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

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

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

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

        return 0;
}

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

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

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

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

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

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

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

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

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

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

        trace_nfsd_clid_admin_expired(&clp->cl_clientid);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        lockdep_assert_held(&nn->client_lock);

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

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

        lockdep_assert_held(&nn->client_lock);

        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);
        trace_nfsd_clid_confirmed(&clp->cl_clientid);
        renew_client_locked(clp);
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

/*
 * Set the exchange_id flags returned by the server.
 */
static void
nfsd4_set_ex_flags(struct nfs4_client *new, struct nfsd4_exchange_id *clid)
{
#ifdef CONFIG_NFSD_PNFS
        new->cl_exchange_flags |= EXCHGID4_FLAG_USE_PNFS_MDS;
#else
        new->cl_exchange_flags |= EXCHGID4_FLAG_USE_NON_PNFS;
#endif

        /* 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_openowners(struct nfs4_client *clp)
{
        struct nfs4_openowner *oo;

        list_for_each_entry(oo, &clp->cl_openowners, oo_perclient) {
                if (!list_empty(&oo->oo_owner.so_stateids))
                        return true;
        }
        return false;
}

static bool client_has_state(struct nfs4_client *clp)
{
        return client_has_openowners(clp)
#ifdef CONFIG_NFSD_PNFS
                || !list_empty(&clp->cl_lo_states)
#endif
                || !list_empty(&clp->cl_delegations)
                || !list_empty(&clp->cl_sessions)
                || !list_empty(&clp->async_copies);
}

static __be32 copy_impl_id(struct nfs4_client *clp,
                                struct nfsd4_exchange_id *exid)
{
        if (!exid->nii_domain.data)
                return 0;
        xdr_netobj_dup(&clp->cl_nii_domain, &exid->nii_domain, GFP_KERNEL);
        if (!clp->cl_nii_domain.data)
                return nfserr_jukebox;
        xdr_netobj_dup(&clp->cl_nii_name, &exid->nii_name, GFP_KERNEL);
        if (!clp->cl_nii_name.data)
                return nfserr_jukebox;
        clp->cl_nii_time = exid->nii_time;
        return 0;
}

__be32
nfsd4_exchange_id(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        struct nfsd4_exchange_id *exid = &u->exchange_id;
        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 %u\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;

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

        switch (exid->spa_how) {
        case SP4_MACH_CRED:
                exid->spo_must_enforce[0] = 0;
                exid->spo_must_enforce[1] = (
                        1 << (OP_BIND_CONN_TO_SESSION - 32) |
                        1 << (OP_EXCHANGE_ID - 32) |
                        1 << (OP_CREATE_SESSION - 32) |
                        1 << (OP_DESTROY_SESSION - 32) |
                        1 << (OP_DESTROY_CLIENTID - 32));

                exid->spo_must_allow[0] &= (1 << (OP_CLOSE) |
                                        1 << (OP_OPEN_DOWNGRADE) |
                                        1 << (OP_LOCKU) |
                                        1 << (OP_DELEGRETURN));

                exid->spo_must_allow[1] &= (
                                        1 << (OP_TEST_STATEID - 32) |
                                        1 << (OP_FREE_STATEID - 32));
                if (!svc_rqst_integrity_protected(rqstp)) {
                        status = nfserr_inval;
                        goto out_nolock;
                }
                /*
                 * Sometimes userspace doesn't give us a principal.
                 * Which is a bug, really.  Anyway, we can't enforce
                 * MACH_CRED in that case, better to give up now:
                 */
                if (!new->cl_cred.cr_principal &&
                                        !new->cl_cred.cr_raw_principal) {
                        status = nfserr_serverfault;
                        goto out_nolock;
                }
                new->cl_mach_cred = true;
                break;
        case SP4_NONE:
                break;
        default:                                /* checked by xdr code */
                WARN_ON_ONCE(1);
                fallthrough;
        case SP4_SSV:
                status = nfserr_encr_alg_unsupp;
                goto out_nolock;
        }

        /* 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 (!nfsd4_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;
                        trace_nfsd_clid_confirmed_r(conf);
                        goto out_copy;
                }
                if (!creds_match) { /* case 3 */
                        if (client_has_state(conf)) {
                                status = nfserr_clid_inuse;
                                trace_nfsd_clid_cred_mismatch(conf, rqstp);
                                goto out;
                        }
                        goto out_new;
                }
                if (verfs_match) { /* case 2 */
                        conf->cl_exchange_flags |= EXCHGID4_FLAG_CONFIRMED_R;
                        trace_nfsd_clid_confirmed_r(conf);
                        goto out_copy;
                }
                /* case 5, client reboot */
                trace_nfsd_clid_verf_mismatch(conf, rqstp, &verf);
                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, new owner ID */
        trace_nfsd_clid_fresh(new);

out_new:
        if (conf) {
                status = mark_client_expired_locked(conf);
                if (status)
                        goto out;
                trace_nfsd_clid_replaced(&conf->cl_clientid);
        }
        new->cl_minorversion = cstate->minorversion;
        new->cl_spo_must_allow.u.words[0] = exid->spo_must_allow[0];
        new->cl_spo_must_allow.u.words[1] = exid->spo_must_allow[1];

        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);
out_nolock:
        if (new)
                expire_client(new);
        if (unconf) {
                trace_nfsd_clid_expire_unconf(&unconf->cl_clientid);
                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:
         * Note that we always allow at least one slot, because our
         * accounting is soft and provides no guarantees either way.
         */
        ca->maxreqs = nfsd4_get_drc_mem(ca, nn);

        return nfs_ok;
}

/*
 * Server's NFSv4.1 backchannel support is AUTH_SYS-only for now.
 * These are based on similar macros in linux/sunrpc/msg_prot.h .
 */
#define RPC_MAX_HEADER_WITH_AUTH_SYS \
        (RPC_CALLHDRSIZE + 2 * (2 + UNX_CALLSLACK))

#define RPC_MAX_REPHEADER_WITH_AUTH_SYS \
        (RPC_REPHDRSIZE + (2 + NUL_REPLYSLACK))

#define NFSD_CB_MAX_REQ_SZ      ((NFS4_enc_cb_recall_sz + \
                                 RPC_MAX_HEADER_WITH_AUTH_SYS) * sizeof(__be32))
#define NFSD_CB_MAX_RESP_SZ     ((NFS4_dec_cb_recall_sz + \
                                 RPC_MAX_REPHEADER_WITH_AUTH_SYS) * \
                                 sizeof(__be32))

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

        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, union nfsd4_op_u *u)
{
        struct nfsd4_create_session *cr_ses = &u->create_session;
        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 (!nfsd4_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) {
                        if (status == nfserr_replay_cache)
                                status = nfsd4_replay_create_session(cr_ses, cs_slot);
                        goto out_free_conn;
                }
        } else if (unconf) {
                status = nfserr_clid_inuse;
                if (!same_creds(&unconf->cl_cred, &rqstp->rq_cred) ||
                    !rpc_cmp_addr(sa, (struct sockaddr *) &unconf->cl_addr)) {
                        trace_nfsd_clid_cred_mismatch(unconf, rqstp);
                        goto out_free_conn;
                }
                status = nfserr_wrong_cred;
                if (!nfsd4_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;
                        }
                        trace_nfsd_clid_replaced(&old->cl_clientid);
                }
                move_to_confirmed(unconf);
                conf = unconf;
        } else {
                status = nfserr_stale_clientid;
                goto out_free_conn;
        }
        status = nfs_ok;
        /* Persistent sessions are not supported */
        cr_ses->flags &= ~SESSION4_PERSIST;
        /* Upshifting from TCP to RDMA is not supported */
        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);
        if (conf == unconf)
                fsnotify_dentry(conf->cl_nfsd_info_dentry, FS_MODIFY);
        /* 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,
                union nfsd4_op_u *u)
{
        struct nfsd4_backchannel_ctl *bc = &u->backchannel_ctl;
        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;
}

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_match_existing_connection(struct svc_rqst *rqst,
                struct nfsd4_session *session, u32 req, struct nfsd4_conn **conn)
{
        struct nfs4_client *clp = session->se_client;
        struct svc_xprt *xpt = rqst->rq_xprt;
        struct nfsd4_conn *c;
        __be32 status;

        /* Following the last paragraph of RFC 5661 Section 18.34.3: */
        spin_lock(&clp->cl_lock);
        c = __nfsd4_find_conn(xpt, session);
        if (!c)
                status = nfserr_noent;
        else if (req == c->cn_flags)
                status = nfs_ok;
        else if (req == NFS4_CDFC4_FORE_OR_BOTH &&
                                c->cn_flags != NFS4_CDFC4_BACK)
                status = nfs_ok;
        else if (req == NFS4_CDFC4_BACK_OR_BOTH &&
                                c->cn_flags != NFS4_CDFC4_FORE)
                status = nfs_ok;
        else
                status = nfserr_inval;
        spin_unlock(&clp->cl_lock);
        if (status == nfs_ok && conn)
                *conn = c;
        return status;
}

__be32 nfsd4_bind_conn_to_session(struct svc_rqst *rqstp,
                     struct nfsd4_compound_state *cstate,
                     union nfsd4_op_u *u)
{
        struct nfsd4_bind_conn_to_session *bcts = &u->bind_conn_to_session;
        __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 (!nfsd4_mach_creds_match(session->se_client, rqstp))
                goto out;
        status = nfsd4_match_existing_connection(rqstp, session,
                        bcts->dir, &conn);
        if (status == nfs_ok) {
                if (bcts->dir == NFS4_CDFC4_FORE_OR_BOTH ||
                                bcts->dir == NFS4_CDFC4_BACK)
                        conn->cn_flags |= NFS4_CDFC4_BACK;
                nfsd4_probe_callback(session->se_client);
                goto out;
        }
        if (status == nfserr_inval)
                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_compound_state *cstate, struct nfs4_sessionid *sid)
{
        if (!cstate->session)
                return false;
        return !memcmp(sid, &cstate->session->se_sessionid, sizeof(*sid));
}

__be32
nfsd4_destroy_session(struct svc_rqst *r, struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        struct nfs4_sessionid *sessionid = &u->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, sessionid)) {
                if (!nfsd4_last_compound_op(r))
                        goto out;
                ref_held_by_me++;
        }
        dump_sessionid(__func__, sessionid);
        spin_lock(&nn->client_lock);
        ses = find_in_sessionid_hashtbl(sessionid, net, &status);
        if (!ses)
                goto out_client_lock;
        status = nfserr_wrong_cred;
        if (!nfsd4_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 __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;
}

static bool replay_matches_cache(struct svc_rqst *rqstp,
                 struct nfsd4_sequence *seq, struct nfsd4_slot *slot)
{
        struct nfsd4_compoundargs *argp = rqstp->rq_argp;

        if ((bool)(slot->sl_flags & NFSD4_SLOT_CACHETHIS) !=
            (bool)seq->cachethis)
                return false;
        /*
         * If there's an error then the reply can have fewer ops than
         * the call.
         */
        if (slot->sl_opcnt < argp->opcnt && !slot->sl_status)
                return false;
        /*
         * But if we cached a reply with *more* ops than the call you're
         * sending us now, then this new call is clearly not really a
         * replay of the old one:
         */
        if (slot->sl_opcnt > argp->opcnt)
                return false;
        /* This is the only check explicitly called by spec: */
        if (!same_creds(&rqstp->rq_cred, &slot->sl_cred))
                return false;
        /*
         * There may be more comparisons we could actually do, but the
         * spec doesn't require us to catch every case where the calls
         * don't match (that would require caching the call as well as
         * the reply), so we don't bother.
         */
        return true;
}

__be32
nfsd4_sequence(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        struct nfsd4_sequence *seq = &u->sequence;
        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;
                status = nfserr_seq_false_retry;
                if (!replay_matches_cache(rqstp, seq, slot))
                        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,
                union nfsd4_op_u *u)
{
        struct nfsd4_destroy_clientid *dc = &u->destroy_clientid;
        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 (!nfsd4_mach_creds_match(clp, rqstp)) {
                clp = NULL;
                status = nfserr_wrong_cred;
                goto out;
        }
        trace_nfsd_clid_destroyed(&clp->cl_clientid);
        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, union nfsd4_op_u *u)
{
        struct nfsd4_reclaim_complete *rc = &u->reclaim_complete;
        struct nfs4_client *clp = cstate->clp;
        __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, &clp->cl_flags))
                goto out;

        status = nfserr_stale_clientid;
        if (is_client_expired(clp))
                /*
                 * 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;
        trace_nfsd_clid_reclaim_complete(&clp->cl_clientid);
        nfsd4_client_record_create(clp);
        inc_reclaim_complete(clp);
out:
        return status;
}

__be32
nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                  union nfsd4_op_u *u)
{
        struct nfsd4_setclientid *setclid = &u->setclientid;
        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;
        spin_lock(&nn->client_lock);
        conf = find_confirmed_client_by_name(&clname, nn);
        if (conf && client_has_state(conf)) {
                status = nfserr_clid_inuse;
                if (clp_used_exchangeid(conf))
                        goto out;
                if (!same_creds(&conf->cl_cred, &rqstp->rq_cred)) {
                        trace_nfsd_clid_cred_mismatch(conf, rqstp);
                        goto out;
                }
        }
        unconf = find_unconfirmed_client_by_name(&clname, nn);
        if (unconf)
                unhash_client_locked(unconf);
        if (conf) {
                if (same_verf(&conf->cl_verifier, &clverifier)) {
                        copy_clid(new, conf);
                        gen_confirm(new, nn);
                } else
                        trace_nfsd_clid_verf_mismatch(conf, rqstp,
                                                      &clverifier);
        } else
                trace_nfsd_clid_fresh(new);
        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) {
                trace_nfsd_clid_expire_unconf(&unconf->cl_clientid);
                expire_client(unconf);
        }
        return status;
}

__be32
nfsd4_setclientid_confirm(struct svc_rqst *rqstp,
                        struct nfsd4_compound_state *cstate,
                        union nfsd4_op_u *u)
{
        struct nfsd4_setclientid_confirm *setclientid_confirm =
                        &u->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,
         * the client may be buggy; this should never happen.
         *
         * Nevertheless, RFC 7530 recommends INUSE for this case:
         */
        status = nfserr_clid_inuse;
        if (unconf && !same_creds(&unconf->cl_cred, &rqstp->rq_cred)) {
                trace_nfsd_clid_cred_mismatch(unconf, rqstp);
                goto out;
        }
        if (conf && !same_creds(&conf->cl_cred, &rqstp->rq_cred)) {
                trace_nfsd_clid_cred_mismatch(conf, rqstp);
                goto out;
        }
        if (!unconf || !same_verf(&confirm, &unconf->cl_confirm)) {
                if (conf && same_verf(&confirm, &conf->cl_confirm)) {
                        status = nfs_ok;
                } else
                        status = nfserr_stale_clientid;
                goto out;
        }
        status = nfs_ok;
        if (conf) {
                old = unconf;
                unhash_client_locked(old);
                nfsd4_change_callback(conf, &unconf->cl_cb_conn);
        } else {
                old = find_confirmed_client_by_name(&unconf->cl_name, nn);
                if (old) {
                        status = nfserr_clid_inuse;
                        if (client_has_state(old)
                                        && !same_creds(&unconf->cl_cred,
                                                        &old->cl_cred)) {
                                old = NULL;
                                goto out;
                        }
                        status = mark_client_expired_locked(old);
                        if (status) {
                                old = NULL;
                                goto out;
                        }
                        trace_nfsd_clid_replaced(&old->cl_clientid);
                }
                move_to_confirmed(unconf);
                conf = unconf;
        }
        get_client_locked(conf);
        spin_unlock(&nn->client_lock);
        if (conf == unconf)
                fsnotify_dentry(conf->cl_nfsd_info_dentry, FS_MODIFY);
        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 svc_fh *fh, unsigned int hashval,
                                struct nfs4_file *fp)
{
        lockdep_assert_held(&state_lock);

        refcount_set(&fp->fi_ref, 1);
        spin_lock_init(&fp->fi_lock);
        INIT_LIST_HEAD(&fp->fi_stateids);
        INIT_LIST_HEAD(&fp->fi_delegations);
        INIT_LIST_HEAD(&fp->fi_clnt_odstate);
        fh_copy_shallow(&fp->fi_fhandle, &fh->fh_handle);
        fp->fi_deleg_file = NULL;
        fp->fi_had_conflict = false;
        fp->fi_share_deny = 0;
        memset(fp->fi_fds, 0, sizeof(fp->fi_fds));
        memset(fp->fi_access, 0, sizeof(fp->fi_access));
        fp->fi_aliased = false;
        fp->fi_inode = d_inode(fh->fh_dentry);
#ifdef CONFIG_NFSD_PNFS
        INIT_LIST_HEAD(&fp->fi_lo_states);
        atomic_set(&fp->fi_lo_recalls, 0);
#endif
        hlist_add_head_rcu(&fp->fi_hash, &file_hashtbl[hashval]);
}

void
nfsd4_free_slabs(void)
{
        kmem_cache_destroy(client_slab);
        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);
        kmem_cache_destroy(odstate_slab);
}

int
nfsd4_init_slabs(void)
{
        client_slab = kmem_cache_create("nfsd4_clients",
                        sizeof(struct nfs4_client), 0, 0, NULL);
        if (client_slab == NULL)
                goto out;
        openowner_slab = kmem_cache_create("nfsd4_openowners",
                        sizeof(struct nfs4_openowner), 0, 0, NULL);
        if (openowner_slab == NULL)
                goto out_free_client_slab;
        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;
        odstate_slab = kmem_cache_create("nfsd4_odstate",
                        sizeof(struct nfs4_clnt_odstate), 0, 0, NULL);
        if (odstate_slab == NULL)
                goto out_free_deleg_slab;
        return 0;

out_free_deleg_slab:
        kmem_cache_destroy(deleg_slab);
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_free_client_slab:
        kmem_cache_destroy(client_slab);
out:
        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 = nfs4_get_stateowner(so);
        }
}

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;

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

        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_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;

        lockdep_assert_held(&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)
                        continue;
                if (local->st_stid.sc_type == NFS4_OPEN_STID) {
                        ret = local;
                        refcount_inc(&ret->st_stid.sc_count);
                        break;
                }
        }
        return ret;
}

static __be32
nfsd4_verify_open_stid(struct nfs4_stid *s)
{
        __be32 ret = nfs_ok;

        switch (s->sc_type) {
        default:
                break;
        case 0:
        case NFS4_CLOSED_STID:
        case NFS4_CLOSED_DELEG_STID:
                ret = nfserr_bad_stateid;
                break;
        case NFS4_REVOKED_DELEG_STID:
                ret = nfserr_deleg_revoked;
        }
        return ret;
}

/* Lock the stateid st_mutex, and deal with races with CLOSE */
static __be32
nfsd4_lock_ol_stateid(struct nfs4_ol_stateid *stp)
{
        __be32 ret;

        mutex_lock_nested(&stp->st_mutex, LOCK_STATEID_MUTEX);
        ret = nfsd4_verify_open_stid(&stp->st_stid);
        if (ret != nfs_ok)
                mutex_unlock(&stp->st_mutex);
        return ret;
}

static struct nfs4_ol_stateid *
nfsd4_find_and_lock_existing_open(struct nfs4_file *fp, struct nfsd4_open *open)
{
        struct nfs4_ol_stateid *stp;
        for (;;) {
                spin_lock(&fp->fi_lock);
                stp = nfsd4_find_existing_open(fp, open);
                spin_unlock(&fp->fi_lock);
                if (!stp || nfsd4_lock_ol_stateid(stp) == nfs_ok)
                        break;
                nfs4_put_stid(&stp->st_stid);
        }
        return stp;
}

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_stateowner(&oo->oo_owner);

        spin_unlock(&clp->cl_lock);
        return ret;
}

static struct nfs4_ol_stateid *
init_open_stateid(struct nfs4_file *fp, struct nfsd4_open *open)
{

        struct nfs4_openowner *oo = open->op_openowner;
        struct nfs4_ol_stateid *retstp = NULL;
        struct nfs4_ol_stateid *stp;

        stp = open->op_stp;
        /* We are moving these outside of the spinlocks to avoid the warnings */
        mutex_init(&stp->st_mutex);
        mutex_lock_nested(&stp->st_mutex, OPEN_STATEID_MUTEX);

retry:
        spin_lock(&oo->oo_owner.so_client->cl_lock);
        spin_lock(&fp->fi_lock);

        retstp = nfsd4_find_existing_open(fp, open);
        if (retstp)
                goto out_unlock;

        open->op_stp = NULL;
        refcount_inc(&stp->st_stid.sc_count);
        stp->st_stid.sc_type = NFS4_OPEN_STID;
        INIT_LIST_HEAD(&stp->st_locks);
        stp->st_stateowner = nfs4_get_stateowner(&oo->oo_owner);
        get_nfs4_file(fp);
        stp->st_stid.sc_file = fp;
        stp->st_access_bmap = 0;
        stp->st_deny_bmap = 0;
        stp->st_openstp = NULL;
        list_add(&stp->st_perstateowner, &oo->oo_owner.so_stateids);
        list_add(&stp->st_perfile, &fp->fi_stateids);

out_unlock:
        spin_unlock(&fp->fi_lock);
        spin_unlock(&oo->oo_owner.so_client->cl_lock);
        if (retstp) {
                /* Handle races with CLOSE */
                if (nfsd4_lock_ol_stateid(retstp) != nfs_ok) {
                        nfs4_put_stid(&retstp->st_stid);
                        goto retry;
                }
                /* To keep mutex tracking happy */
                mutex_unlock(&stp->st_mutex);
                stp = retstp;
        }
        return stp;
}

/*
 * 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, refcount_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 = ktime_get_boottime_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 svc_fh *fh, unsigned int hashval)
{
        struct nfs4_file *fp;

        hlist_for_each_entry_rcu(fp, &file_hashtbl[hashval], fi_hash,
                                lockdep_is_held(&state_lock)) {
                if (fh_match(&fp->fi_fhandle, &fh->fh_handle)) {
                        if (refcount_inc_not_zero(&fp->fi_ref))
                                return fp;
                }
        }
        return NULL;
}

static struct nfs4_file *insert_file(struct nfs4_file *new, struct svc_fh *fh,
                                     unsigned int hashval)
{
        struct nfs4_file *fp;
        struct nfs4_file *ret = NULL;
        bool alias_found = false;

        spin_lock(&state_lock);
        hlist_for_each_entry_rcu(fp, &file_hashtbl[hashval], fi_hash,
                                 lockdep_is_held(&state_lock)) {
                if (fh_match(&fp->fi_fhandle, &fh->fh_handle)) {
                        if (refcount_inc_not_zero(&fp->fi_ref))
                                ret = fp;
                } else if (d_inode(fh->fh_dentry) == fp->fi_inode)
                        fp->fi_aliased = alias_found = true;
        }
        if (likely(ret == NULL)) {
                nfsd4_init_file(fh, hashval, new);
                new->fi_aliased = alias_found;
                ret = new;
        }
        spin_unlock(&state_lock);
        return ret;
}

static struct nfs4_file * find_file(struct svc_fh *fh)
{
        struct nfs4_file *fp;
        unsigned int hashval = file_hashval(fh);

        rcu_read_lock();
        fp = find_file_locked(fh, hashval);
        rcu_read_unlock();
        return fp;
}

static struct nfs4_file *
find_or_add_file(struct nfs4_file *new, struct svc_fh *fh)
{
        struct nfs4_file *fp;
        unsigned int hashval = file_hashval(fh);

        rcu_read_lock();
        fp = find_file_locked(fh, hashval);
        rcu_read_unlock();
        if (fp)
                return fp;

        return insert_file(new, fh, hashval);
}

/*
 * 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);
        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;
}

static void nfsd4_cb_recall_prepare(struct nfsd4_callback *cb)
{
        struct nfs4_delegation *dp = cb_to_delegation(cb);
        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 (delegation_hashed(dp) && dp->dl_time == 0) {
                dp->dl_time = ktime_get_boottime_seconds();
                list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);
        }
        spin_unlock(&state_lock);
}

static int nfsd4_cb_recall_done(struct nfsd4_callback *cb,
                struct rpc_task *task)
{
        struct nfs4_delegation *dp = cb_to_delegation(cb);

        if (dp->dl_stid.sc_type == NFS4_CLOSED_DELEG_STID ||
            dp->dl_stid.sc_type == NFS4_REVOKED_DELEG_STID)
                return 1;

        switch (task->tk_status) {
        case 0:
                return 1;
        case -NFS4ERR_DELAY:
                rpc_delay(task, 2 * HZ);
                return 0;
        case -EBADHANDLE:
        case -NFS4ERR_BAD_STATEID:
                /*
                 * Race: client probably got cb_recall before open reply
                 * granting delegation.
                 */
                if (dp->dl_retries--) {
                        rpc_delay(task, 2 * HZ);
                        return 0;
                }
                fallthrough;
        default:
                return 1;
        }
}

static void nfsd4_cb_recall_release(struct nfsd4_callback *cb)
{
        struct nfs4_delegation *dp = cb_to_delegation(cb);

        nfs4_put_stid(&dp->dl_stid);
}

static const struct nfsd4_callback_ops nfsd4_cb_recall_ops = {
        .prepare        = nfsd4_cb_recall_prepare,
        .done           = nfsd4_cb_recall_done,
        .release        = nfsd4_cb_recall_release,
};

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
         * i_lock) we know the server hasn't removed the lease yet, and
         * we know it's safe to take a reference.
         */
        refcount_inc(&dp->dl_stid.sc_count);
        nfsd4_run_cb(&dp->dl_recall);
}

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

        trace_nfsd_cb_recall(&dp->dl_stid);

        /*
         * 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;
        nfsd_break_one_deleg(dp);
        spin_unlock(&fp->fi_lock);
        return ret;
}

static bool nfsd_breaker_owns_lease(struct file_lock *fl)
{
        struct nfs4_delegation *dl = fl->fl_owner;
        struct svc_rqst *rqst;
        struct nfs4_client *clp;

        if (!i_am_nfsd())
                return NULL;
        rqst = kthread_data(current);
        /* Note rq_prog == NFS_ACL_PROGRAM is also possible: */
        if (rqst->rq_prog != NFS_PROGRAM || rqst->rq_vers < 4)
                return NULL;
        clp = *(rqst->rq_lease_breaker);
        return dl->dl_stid.sc_client == clp;
}

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

static const struct lock_manager_operations nfsd_lease_mng_ops = {
        .lm_breaker_owns_lease = nfsd_breaker_owns_lease,
        .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 struct nfs4_client *lookup_clientid(clientid_t *clid, bool sessions,
                                                struct nfsd_net *nn)
{
        struct nfs4_client *found;

        spin_lock(&nn->client_lock);
        found = find_confirmed_client(clid, sessions, nn);
        if (found)
                atomic_inc(&found->cl_rpc_users);
        spin_unlock(&nn->client_lock);
        return found;
}

static __be32 set_client(clientid_t *clid,
                struct nfsd4_compound_state *cstate,
                struct nfsd_net *nn)
{
        if (cstate->clp) {
                if (!same_clid(&cstate->clp->cl_clientid, clid))
                        return nfserr_stale_clientid;
                return nfs_ok;
        }
        if (STALE_CLIENTID(clid, nn))
                return nfserr_stale_clientid;
        /*
         * We're in the 4.0 case (otherwise the SEQUENCE op would have
         * set cstate->clp), so session = false:
         */
        cstate->clp = lookup_clientid(clid, false, nn);
        if (!cstate->clp)
                return nfserr_expired;
        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;

        /*
         * 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 = set_client(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;

        if (nfsd4_has_session(cstate) &&
            (cstate->current_fh.fh_export->ex_flags & NFSEXP_PNFS)) {
                open->op_odstate = alloc_clnt_odstate(clp);
                if (!open->op_odstate)
                        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|NFS4_REVOKED_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;
        if (deleg->dl_stid.sc_type == NFS4_REVOKED_DELEG_STID) {
                nfs4_put_stid(&deleg->dl_stid);
                if (cl->cl_minorversion)
                        status = nfserr_deleg_revoked;
                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 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, (time64_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 nfsd_file *nf = 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_file_acquire(rqstp, cur_fh, access, &nf);
                if (status)
                        goto out_put_access;
                spin_lock(&fp->fi_lock);
                if (!fp->fi_fds[oflag]) {
                        fp->fi_fds[oflag] = nf;
                        nf = NULL;
                }
        }
        spin_unlock(&fp->fi_lock);
        if (nf)
                nfsd_file_put(nf);

        status = nfserrno(nfsd_open_break_lease(cur_fh->fh_dentry->d_inode,
                                                                access));
        if (status)
                goto out_put_access;

        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 = stp->st_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) {
                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;
}

/* 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_delegation *dp,
                                                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)dp;
        fl->fl_pid = current->tgid;
        fl->fl_file = dp->dl_stid.sc_file->fi_deleg_file->nf_file;
        return fl;
}

static int nfsd4_check_conflicting_opens(struct nfs4_client *clp,
                                         struct nfs4_file *fp)
{
        struct nfs4_ol_stateid *st;
        struct file *f = fp->fi_deleg_file->nf_file;
        struct inode *ino = locks_inode(f);
        int writes;

        writes = atomic_read(&ino->i_writecount);
        if (!writes)
                return 0;
        /*
         * There could be multiple filehandles (hence multiple
         * nfs4_files) referencing this file, but that's not too
         * common; let's just give up in that case rather than
         * trying to go look up all the clients using that other
         * nfs4_file as well:
         */
        if (fp->fi_aliased)
                return -EAGAIN;
        /*
         * If there's a close in progress, make sure that we see it
         * clear any fi_fds[] entries before we see it decrement
         * i_writecount:
         */
        smp_mb__after_atomic();

        if (fp->fi_fds[O_WRONLY])
                writes--;
        if (fp->fi_fds[O_RDWR])
                writes--;
        if (writes > 0)
                return -EAGAIN; /* There may be non-NFSv4 writers */
        /*
         * It's possible there are non-NFSv4 write opens in progress,
         * but if they haven't incremented i_writecount yet then they
         * also haven't called break lease yet; so, they'll break this
         * lease soon enough.  So, all that's left to check for is NFSv4
         * opens:
         */
        spin_lock(&fp->fi_lock);
        list_for_each_entry(st, &fp->fi_stateids, st_perfile) {
                if (st->st_openstp == NULL /* it's an open */ &&
                    access_permit_write(st) &&
                    st->st_stid.sc_client != clp) {
                        spin_unlock(&fp->fi_lock);
                        return -EAGAIN;
                }
        }
        spin_unlock(&fp->fi_lock);
        /*
         * There's a small chance that we could be racing with another
         * NFSv4 open.  However, any open that hasn't added itself to
         * the fi_stateids list also hasn't called break_lease yet; so,
         * they'll break this lease soon enough.
         */
        return 0;
}

static struct nfs4_delegation *
nfs4_set_delegation(struct nfs4_client *clp, struct svc_fh *fh,
                    struct nfs4_file *fp, struct nfs4_clnt_odstate *odstate)
{
        int status = 0;
        struct nfs4_delegation *dp;
        struct nfsd_file *nf;
        struct file_lock *fl;

        /*
         * The fi_had_conflict and nfs_get_existing_delegation checks
         * here are just optimizations; we'll need to recheck them at
         * the end:
         */
        if (fp->fi_had_conflict)
                return ERR_PTR(-EAGAIN);

        nf = find_readable_file(fp);
        if (!nf) {
                /*
                 * We probably could attempt another open and get a read
                 * delegation, but for now, don't bother until the
                 * client actually sends us one.
                 */
                return ERR_PTR(-EAGAIN);
        }
        spin_lock(&state_lock);
        spin_lock(&fp->fi_lock);
        if (nfs4_delegation_exists(clp, fp))
                status = -EAGAIN;
        else if (!fp->fi_deleg_file) {
                fp->fi_deleg_file = nf;
                /* increment early to prevent fi_deleg_file from being
                 * cleared */
                fp->fi_delegees = 1;
                nf = NULL;
        } else
                fp->fi_delegees++;
        spin_unlock(&fp->fi_lock);
        spin_unlock(&state_lock);
        if (nf)
                nfsd_file_put(nf);
        if (status)
                return ERR_PTR(status);

        status = -ENOMEM;
        dp = alloc_init_deleg(clp, fp, fh, odstate);
        if (!dp)
                goto out_delegees;

        fl = nfs4_alloc_init_lease(dp, NFS4_OPEN_DELEGATE_READ);
        if (!fl)
                goto out_clnt_odstate;

        status = vfs_setlease(fp->fi_deleg_file->nf_file, fl->fl_type, &fl, NULL);
        if (fl)
                locks_free_lock(fl);
        if (status)
                goto out_clnt_odstate;
        status = nfsd4_check_conflicting_opens(clp, fp);
        if (status)
                goto out_unlock;

        spin_lock(&state_lock);
        spin_lock(&fp->fi_lock);
        if (fp->fi_had_conflict)
                status = -EAGAIN;
        else
                status = hash_delegation_locked(dp, fp);
        spin_unlock(&fp->fi_lock);
        spin_unlock(&state_lock);

        if (status)
                goto out_unlock;

        return dp;
out_unlock:
        vfs_setlease(fp->fi_deleg_file->nf_file, F_UNLCK, NULL, (void **)&dp);
out_clnt_odstate:
        put_clnt_odstate(dp->dl_clnt_odstate);
        nfs4_put_stid(&dp->dl_stid);
out_delegees:
        put_deleg_file(fp);
        return ERR_PTR(status);
}

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, *and* until
                         * NLM locks have all been reclaimed:
                         */
                        if (locks_in_grace(clp->net))
                                goto out_no_deleg;
                        if (!cb_up || !(oo->oo_flags & NFS4_OO_CONFIRMED))
                                goto out_no_deleg;
                        break;
                default:
                        goto out_no_deleg;
        }
        dp = nfs4_set_delegation(clp, fh, stp->st_stid.sc_file, stp->st_clnt_odstate);
        if (IS_ERR(dp))
                goto out_no_deleg;

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

        trace_nfsd_deleg_read(&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;
        bool new_stp = false;

        /*
         * 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);
        if (fp != open->op_file) {
                status = nfs4_check_deleg(cl, open, &dp);
                if (status)
                        goto out;
                stp = nfsd4_find_and_lock_existing_open(fp, open);
        } else {
                open->op_file = NULL;
                status = nfserr_bad_stateid;
                if (nfsd4_is_deleg_cur(open))
                        goto out;
        }

        if (!stp) {
                stp = init_open_stateid(fp, open);
                if (!open->op_stp)
                        new_stp = true;
        }

        /*
         * OPEN the file, or upgrade an existing OPEN.
         * If truncate fails, the OPEN fails.
         *
         * stp is already locked.
         */
        if (!new_stp) {
                /* Stateid was found, this is an OPEN upgrade */
                status = nfs4_upgrade_open(rqstp, fp, current_fh, stp, open);
                if (status) {
                        mutex_unlock(&stp->st_mutex);
                        goto out;
                }
        } else {
                status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open);
                if (status) {
                        stp->st_stid.sc_type = NFS4_CLOSED_STID;
                        release_open_stateid(stp);
                        mutex_unlock(&stp->st_mutex);
                        goto out;
                }

                stp->st_clnt_odstate = find_or_hash_clnt_odstate(fp,
                                                        open->op_odstate);
                if (stp->st_clnt_odstate == open->op_odstate)
                        open->op_odstate = NULL;
        }

        nfs4_inc_and_copy_stateid(&open->op_stateid, &stp->st_stid);
        mutex_unlock(&stp->st_mutex);

        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;
        trace_nfsd_open(&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)
                open->op_openowner->oo_flags |= NFS4_OO_CONFIRMED;
        /*
        * To finish the open response, we just need to set the rflags.
        */
        open->op_rflags = NFS4_OPEN_RESULT_LOCKTYPE_POSIX;
        if (nfsd4_has_session(&resp->cstate))
                open->op_rflags |= NFS4_OPEN_RESULT_MAY_NOTIFY_LOCK;
        else if (!(open->op_openowner->oo_flags & NFS4_OO_CONFIRMED))
                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)
{
        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)
                kmem_cache_free(file_slab, open->op_file);
        if (open->op_stp)
                nfs4_put_stid(&open->op_stp->st_stid);
        if (open->op_odstate)
                kmem_cache_free(odstate_slab, open->op_odstate);
}

__be32
nfsd4_renew(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
            union nfsd4_op_u *u)
{
        clientid_t *clid = &u->renew;
        struct nfs4_client *clp;
        __be32 status;
        struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);

        trace_nfsd_clid_renew(clid);
        status = set_client(clid, cstate, nn);
        if (status)
                return status;
        clp = cstate->clp;
        if (!list_empty(&clp->cl_delegations)
                        && clp->cl_cb_state != NFSD4_CB_UP)
                return nfserr_cb_path_down;
        return nfs_ok;
}

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

        trace_nfsd_grace_complete(nn);
        nn->grace_ended = true;
        /*
         * If the server goes down again right now, an NFSv4
         * client will still be allowed to reclaim after it comes back up,
         * even if it hasn't yet had a chance to reclaim state this time.
         *
         */
        nfsd4_record_grace_done(nn);
        /*
         * At this point, NFSv4 clients can still reclaim.  But if the
         * server crashes, any that have not yet reclaimed will be out
         * of luck on the next boot.
         *
         * (NFSv4.1+ clients are considered to have reclaimed once they
         * call RECLAIM_COMPLETE.  NFSv4.0 clients are considered to
         * have reclaimed after their first OPEN.)
         */
        locks_end_grace(&nn->nfsd4_manager);
        /*
         * At this point, and once lockd and/or any other containers
         * exit their grace period, further reclaims will fail and
         * regular locking can resume.
         */
}

/*
 * If we've waited a lease period but there are still clients trying to
 * reclaim, wait a little longer to give them a chance to finish.
 */
static bool clients_still_reclaiming(struct nfsd_net *nn)
{
        time64_t double_grace_period_end = nn->boot_time +
                                           2 * nn->nfsd4_lease;

        if (nn->track_reclaim_completes &&
                        atomic_read(&nn->nr_reclaim_complete) ==
                        nn->reclaim_str_hashtbl_size)
                return false;
        if (!nn->somebody_reclaimed)
                return false;
        nn->somebody_reclaimed = false;
        /*
         * If we've given them *two* lease times to reclaim, and they're
         * still not done, give up:
         */
        if (ktime_get_boottime_seconds() > double_grace_period_end)
                return false;
        return true;
}

struct laundry_time {
        time64_t cutoff;
        time64_t new_timeo;
};

static bool state_expired(struct laundry_time *lt, time64_t last_refresh)
{
        time64_t time_remaining;

        if (last_refresh < lt->cutoff)
                return true;
        time_remaining = last_refresh - lt->cutoff;
        lt->new_timeo = min(lt->new_timeo, time_remaining);
        return false;
}

#ifdef CONFIG_NFSD_V4_2_INTER_SSC
void nfsd4_ssc_init_umount_work(struct nfsd_net *nn)
{
        spin_lock_init(&nn->nfsd_ssc_lock);
        INIT_LIST_HEAD(&nn->nfsd_ssc_mount_list);
        init_waitqueue_head(&nn->nfsd_ssc_waitq);
}
EXPORT_SYMBOL_GPL(nfsd4_ssc_init_umount_work);

/*
 * This is called when nfsd is being shutdown, after all inter_ssc
 * cleanup were done, to destroy the ssc delayed unmount list.
 */
static void nfsd4_ssc_shutdown_umount(struct nfsd_net *nn)
{
        struct nfsd4_ssc_umount_item *ni = NULL;
        struct nfsd4_ssc_umount_item *tmp;

        spin_lock(&nn->nfsd_ssc_lock);
        list_for_each_entry_safe(ni, tmp, &nn->nfsd_ssc_mount_list, nsui_list) {
                list_del(&ni->nsui_list);
                spin_unlock(&nn->nfsd_ssc_lock);
                mntput(ni->nsui_vfsmount);
                kfree(ni);
                spin_lock(&nn->nfsd_ssc_lock);
        }
        spin_unlock(&nn->nfsd_ssc_lock);
}

static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
{
        bool do_wakeup = false;
        struct nfsd4_ssc_umount_item *ni = NULL;
        struct nfsd4_ssc_umount_item *tmp;

        spin_lock(&nn->nfsd_ssc_lock);
        list_for_each_entry_safe(ni, tmp, &nn->nfsd_ssc_mount_list, nsui_list) {
                if (time_after(jiffies, ni->nsui_expire)) {
                        if (refcount_read(&ni->nsui_refcnt) > 1)
                                continue;

                        /* mark being unmount */
                        ni->nsui_busy = true;
                        spin_unlock(&nn->nfsd_ssc_lock);
                        mntput(ni->nsui_vfsmount);
                        spin_lock(&nn->nfsd_ssc_lock);

                        /* waiters need to start from begin of list */
                        list_del(&ni->nsui_list);
                        kfree(ni);

                        /* wakeup ssc_connect waiters */
                        do_wakeup = true;
                        continue;
                }
                break;
        }
        if (do_wakeup)
                wake_up_all(&nn->nfsd_ssc_waitq);
        spin_unlock(&nn->nfsd_ssc_lock);
}
#endif

static time64_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 nfsd4_blocked_lock *nbl;
        struct list_head *pos, *next, reaplist;
        struct laundry_time lt = {
                .cutoff = ktime_get_boottime_seconds() - nn->nfsd4_lease,
                .new_timeo = nn->nfsd4_lease
        };
        struct nfs4_cpntf_state *cps;
        copy_stateid_t *cps_t;
        int i;

        if (clients_still_reclaiming(nn)) {
                lt.new_timeo = 0;
                goto out;
        }
        nfsd4_end_grace(nn);
        INIT_LIST_HEAD(&reaplist);

        spin_lock(&nn->s2s_cp_lock);
        idr_for_each_entry(&nn->s2s_cp_stateids, cps_t, i) {
                cps = container_of(cps_t, struct nfs4_cpntf_state, cp_stateid);
                if (cps->cp_stateid.sc_type == NFS4_COPYNOTIFY_STID &&
                                state_expired(&lt, cps->cpntf_time))
                        _free_cpntf_state_locked(nn, cps);
        }
        spin_unlock(&nn->s2s_cp_lock);

        spin_lock(&nn->client_lock);
        list_for_each_safe(pos, next, &nn->client_lru) {
                clp = list_entry(pos, struct nfs4_client, cl_lru);
                if (!state_expired(&lt, clp->cl_time))
                        break;
                if (mark_client_expired_locked(clp))
                        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);
                trace_nfsd_clid_purged(&clp->cl_clientid);
                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 (!state_expired(&lt, dp->dl_time))
                        break;
                WARN_ON(!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 (!state_expired(&lt, oo->oo_time))
                        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);

        /*
         * It's possible for a client to try and acquire an already held lock
         * that is being held for a long time, and then lose interest in it.
         * So, we clean out any un-revisited request after a lease period
         * under the assumption that the client is no longer interested.
         *
         * RFC5661, sec. 9.6 states that the client must not rely on getting
         * notifications and must continue to poll for locks, even when the
         * server supports them. Thus this shouldn't lead to clients blocking
         * indefinitely once the lock does become free.
         */
        BUG_ON(!list_empty(&reaplist));
        spin_lock(&nn->blocked_locks_lock);
        while (!list_empty(&nn->blocked_locks_lru)) {
                nbl = list_first_entry(&nn->blocked_locks_lru,
                                        struct nfsd4_blocked_lock, nbl_lru);
                if (!state_expired(&lt, nbl->nbl_time))
                        break;
                list_move(&nbl->nbl_lru, &reaplist);
                list_del_init(&nbl->nbl_list);
        }
        spin_unlock(&nn->blocked_locks_lock);

        while (!list_empty(&reaplist)) {
                nbl = list_first_entry(&reaplist,
                                        struct nfsd4_blocked_lock, nbl_lru);
                list_del_init(&nbl->nbl_lru);
                free_blocked_lock(nbl);
        }
#ifdef CONFIG_NFSD_V4_2_INTER_SSC
        /* service the server-to-server copy delayed unmount list */
        nfsd4_ssc_expire_umount(nn);
#endif
out:
        return max_t(time64_t, lt.new_timeo, NFSD_LAUNDROMAT_MINTIMEOUT);
}

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

static void
laundromat_main(struct work_struct *laundry)
{
        time64_t t;
        struct delayed_work *dwork = to_delayed_work(laundry);
        struct nfsd_net *nn = container_of(dwork, struct nfsd_net,
                                           laundromat_work);

        t = nfs4_laundromat(nn);
        queue_delayed_work(laundry_wq, &nn->laundromat_work, t*HZ);
}

static inline __be32 nfs4_check_fh(struct svc_fh *fhp, struct nfs4_stid *stp)
{
        if (!fh_match(&fhp->fh_handle, &stp->sc_file->fi_fhandle))
                return nfserr_bad_stateid;
        return nfs_ok;
}

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 (opens_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);
}

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 (nfsd4_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_stid_check_stateid_generation(stateid_t *in, struct nfs4_stid *s, bool has_session)
{
        __be32 ret;

        spin_lock(&s->sc_lock);
        ret = nfsd4_verify_open_stid(s);
        if (ret == nfs_ok)
                ret = check_stateid_generation(in, &s->sc_stateid, has_session);
        spin_unlock(&s->sc_lock);
        return ret;
}

static __be32 nfsd4_check_openowner_confirmed(struct nfs4_ol_stateid *ols)
{
        if (ols->st_stateowner->so_is_open_owner &&
            !(openowner(ols->st_stateowner)->oo_flags & NFS4_OO_CONFIRMED))
                return nfserr_bad_stateid;
        return nfs_ok;
}

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

        if (ZERO_STATEID(stateid) || ONE_STATEID(stateid) ||
                CLOSE_STATEID(stateid))
                return status;
        if (!same_clid(&stateid->si_opaque.so_clid, &cl->cl_clientid))
                return status;
        spin_lock(&cl->cl_lock);
        s = find_stateid_locked(cl, stateid);
        if (!s)
                goto out_unlock;
        status = nfsd4_stid_check_stateid_generation(stateid, s, 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:
                status = nfsd4_check_openowner_confirmed(openlockstateid(s));
                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;
}

__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;
        bool return_revoked = false;

        /*
         *  only return revoked delegations if explicitly asked.
         *  otherwise we report revoked or bad_stateid status.
         */
        if (typemask & NFS4_REVOKED_DELEG_STID)
                return_revoked = true;
        else if (typemask & NFS4_DELEG_STID)
                typemask |= NFS4_REVOKED_DELEG_STID;

        if (ZERO_STATEID(stateid) || ONE_STATEID(stateid) ||
                CLOSE_STATEID(stateid))
                return nfserr_bad_stateid;
        status = set_client(&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;
        if (((*s)->sc_type == NFS4_REVOKED_DELEG_STID) && !return_revoked) {
                nfs4_put_stid(*s);
                if (cstate->minorversion)
                        return nfserr_deleg_revoked;
                return nfserr_bad_stateid;
        }
        return nfs_ok;
}

static struct nfsd_file *
nfs4_find_file(struct nfs4_stid *s, int flags)
{
        if (!s)
                return NULL;

        switch (s->sc_type) {
        case NFS4_DELEG_STID:
                if (WARN_ON_ONCE(!s->sc_file->fi_deleg_file))
                        return NULL;
                return nfsd_file_get(s->sc_file->fi_deleg_file);
        case NFS4_OPEN_STID:
        case NFS4_LOCK_STID:
                if (flags & RD_STATE)
                        return find_readable_file(s->sc_file);
                else
                        return find_writeable_file(s->sc_file);
        }

        return NULL;
}

static __be32
nfs4_check_olstateid(struct nfs4_ol_stateid *ols, int flags)
{
        __be32 status;

        status = nfsd4_check_openowner_confirmed(ols);
        if (status)
                return status;
        return nfs4_check_openmode(ols, flags);
}

static __be32
nfs4_check_file(struct svc_rqst *rqstp, struct svc_fh *fhp, struct nfs4_stid *s,
                struct nfsd_file **nfp, int flags)
{
        int acc = (flags & RD_STATE) ? NFSD_MAY_READ : NFSD_MAY_WRITE;
        struct nfsd_file *nf;
        __be32 status;

        nf = nfs4_find_file(s, flags);
        if (nf) {
                status = nfsd_permission(rqstp, fhp->fh_export, fhp->fh_dentry,
                                acc | NFSD_MAY_OWNER_OVERRIDE);
                if (status) {
                        nfsd_file_put(nf);
                        goto out;
                }
        } else {
                status = nfsd_file_acquire(rqstp, fhp, acc, &nf);
                if (status)
                        return status;
        }
        *nfp = nf;
out:
        return status;
}
static void
_free_cpntf_state_locked(struct nfsd_net *nn, struct nfs4_cpntf_state *cps)
{
        WARN_ON_ONCE(cps->cp_stateid.sc_type != NFS4_COPYNOTIFY_STID);
        if (!refcount_dec_and_test(&cps->cp_stateid.sc_count))
                return;
        list_del(&cps->cp_list);
        idr_remove(&nn->s2s_cp_stateids,
                   cps->cp_stateid.stid.si_opaque.so_id);
        kfree(cps);
}
/*
 * A READ from an inter server to server COPY will have a
 * copy stateid. Look up the copy notify stateid from the
 * idr structure and take a reference on it.
 */
__be32 manage_cpntf_state(struct nfsd_net *nn, stateid_t *st,
                          struct nfs4_client *clp,
                          struct nfs4_cpntf_state **cps)
{
        copy_stateid_t *cps_t;
        struct nfs4_cpntf_state *state = NULL;

        if (st->si_opaque.so_clid.cl_id != nn->s2s_cp_cl_id)
                return nfserr_bad_stateid;
        spin_lock(&nn->s2s_cp_lock);
        cps_t = idr_find(&nn->s2s_cp_stateids, st->si_opaque.so_id);
        if (cps_t) {
                state = container_of(cps_t, struct nfs4_cpntf_state,
                                     cp_stateid);
                if (state->cp_stateid.sc_type != NFS4_COPYNOTIFY_STID) {
                        state = NULL;
                        goto unlock;
                }
                if (!clp)
                        refcount_inc(&state->cp_stateid.sc_count);
                else
                        _free_cpntf_state_locked(nn, state);
        }
unlock:
        spin_unlock(&nn->s2s_cp_lock);
        if (!state)
                return nfserr_bad_stateid;
        if (!clp && state)
                *cps = state;
        return 0;
}

static __be32 find_cpntf_state(struct nfsd_net *nn, stateid_t *st,
                               struct nfs4_stid **stid)
{
        __be32 status;
        struct nfs4_cpntf_state *cps = NULL;
        struct nfs4_client *found;

        status = manage_cpntf_state(nn, st, NULL, &cps);
        if (status)
                return status;

        cps->cpntf_time = ktime_get_boottime_seconds();

        status = nfserr_expired;
        found = lookup_clientid(&cps->cp_p_clid, true, nn);
        if (!found)
                goto out;

        *stid = find_stateid_by_type(found, &cps->cp_p_stateid,
                        NFS4_DELEG_STID|NFS4_OPEN_STID|NFS4_LOCK_STID);
        if (*stid)
                status = nfs_ok;
        else
                status = nfserr_bad_stateid;

        put_client_renew(found);
out:
        nfs4_put_cpntf_state(nn, cps);
        return status;
}

void nfs4_put_cpntf_state(struct nfsd_net *nn, struct nfs4_cpntf_state *cps)
{
        spin_lock(&nn->s2s_cp_lock);
        _free_cpntf_state_locked(nn, cps);
        spin_unlock(&nn->s2s_cp_lock);
}

/*
 * Checks for stateid operations
 */
__be32
nfs4_preprocess_stateid_op(struct svc_rqst *rqstp,
                struct nfsd4_compound_state *cstate, struct svc_fh *fhp,
                stateid_t *stateid, int flags, struct nfsd_file **nfp,
                struct nfs4_stid **cstid)
{
        struct net *net = SVC_NET(rqstp);
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);
        struct nfs4_stid *s = NULL;
        __be32 status;

        if (nfp)
                *nfp = NULL;

        if (ZERO_STATEID(stateid) || ONE_STATEID(stateid)) {
                if (cstid)
                        status = nfserr_bad_stateid;
                else
                        status = check_special_stateids(net, fhp, stateid,
                                                                        flags);
                goto done;
        }

        status = nfsd4_lookup_stateid(cstate, stateid,
                                NFS4_DELEG_STID|NFS4_OPEN_STID|NFS4_LOCK_STID,
                                &s, nn);
        if (status == nfserr_bad_stateid)
                status = find_cpntf_state(nn, stateid, &s);
        if (status)
                return status;
        status = nfsd4_stid_check_stateid_generation(stateid, s,
                        nfsd4_has_session(cstate));
        if (status)
                goto out;

        switch (s->sc_type) {
        case NFS4_DELEG_STID:
                status = nfs4_check_delegmode(delegstateid(s), flags);
                break;
        case NFS4_OPEN_STID:
        case NFS4_LOCK_STID:
                status = nfs4_check_olstateid(openlockstateid(s), flags);
                break;
        default:
                status = nfserr_bad_stateid;
                break;
        }
        if (status)
                goto out;
        status = nfs4_check_fh(fhp, s);

done:
        if (status == nfs_ok && nfp)
                status = nfs4_check_file(rqstp, fhp, s, nfp, flags);
out:
        if (s) {
                if (!status && cstid)
                        *cstid = s;
                else
                        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,
                   union nfsd4_op_u *u)
{
        struct nfsd4_test_stateid *test_stateid = &u->test_stateid;
        struct nfsd4_test_stateid_id *stateid;
        struct nfs4_client *cl = cstate->clp;

        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;
}

static __be32
nfsd4_free_lock_stateid(stateid_t *stateid, struct nfs4_stid *s)
{
        struct nfs4_ol_stateid *stp = openlockstateid(s);
        __be32 ret;

        ret = nfsd4_lock_ol_stateid(stp);
        if (ret)
                goto out_put_stid;

        ret = check_stateid_generation(stateid, &s->sc_stateid, 1);
        if (ret)
                goto out;

        ret = nfserr_locks_held;
        if (check_for_locks(stp->st_stid.sc_file,
                            lockowner(stp->st_stateowner)))
                goto out;

        release_lock_stateid(stp);
        ret = nfs_ok;

out:
        mutex_unlock(&stp->st_mutex);
out_put_stid:
        nfs4_put_stid(s);
        return ret;
}

__be32
nfsd4_free_stateid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                   union nfsd4_op_u *u)
{
        struct nfsd4_free_stateid *free_stateid = &u->free_stateid;
        stateid_t *stateid = &free_stateid->fr_stateid;
        struct nfs4_stid *s;
        struct nfs4_delegation *dp;
        struct nfs4_client *cl = cstate->clp;
        __be32 ret = nfserr_bad_stateid;

        spin_lock(&cl->cl_lock);
        s = find_stateid_locked(cl, stateid);
        if (!s)
                goto out_unlock;
        spin_lock(&s->sc_lock);
        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:
                spin_unlock(&s->sc_lock);
                refcount_inc(&s->sc_count);
                spin_unlock(&cl->cl_lock);
                ret = nfsd4_free_lock_stateid(stateid, s);
                goto out;
        case NFS4_REVOKED_DELEG_STID:
                spin_unlock(&s->sc_lock);
                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 */
        }
        spin_unlock(&s->sc_lock);
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;
        status = nfsd4_lock_ol_stateid(stp);
        if (status != nfs_ok)
                return status;
        status = check_stateid_generation(stateid, &stp->st_stid.sc_stateid, nfsd4_has_session(cstate));
        if (status == nfs_ok)
                status = nfs4_check_fh(current_fh, &stp->st_stid);
        if (status != nfs_ok)
                mutex_unlock(&stp->st_mutex);
        return status;
}

/* 
 * 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;

        trace_nfsd_preprocess(seqid, 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)) {
                mutex_unlock(&stp->st_mutex);
                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,
                   union nfsd4_op_u *u)
{
        struct nfsd4_open_confirm *oc = &u->open_confirm;
        __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) {
                mutex_unlock(&stp->st_mutex);
                goto put_stateid;
        }
        oo->oo_flags |= NFS4_OO_CONFIRMED;
        nfs4_inc_and_copy_stateid(&oc->oc_resp_stateid, &stp->st_stid);
        mutex_unlock(&stp->st_mutex);
        trace_nfsd_open_confirm(oc->oc_seqid, &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, union nfsd4_op_u *u)
{
        struct nfsd4_open_downgrade *od = &u->open_downgrade;
        __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);
        nfs4_inc_and_copy_stateid(&od->od_stateid, &stp->st_stid);
        status = nfs_ok;
put_stateid:
        mutex_unlock(&stp->st_mutex);
        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;
        bool unhashed;
        LIST_HEAD(reaplist);

        spin_lock(&clp->cl_lock);
        unhashed = unhash_open_stateid(s, &reaplist);

        if (clp->cl_minorversion) {
                if (unhashed)
                        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);
                if (unhashed)
                        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,
                union nfsd4_op_u *u)
{
        struct nfsd4_close *close = &u->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; 

        stp->st_stid.sc_type = NFS4_CLOSED_STID;

        /*
         * Technically we don't _really_ have to increment or copy it, since
         * it should just be gone after this operation and we clobber the
         * copied value below, but we continue to do so here just to ensure
         * that racing ops see that there was a state change.
         */
        nfs4_inc_and_copy_stateid(&close->cl_stateid, &stp->st_stid);

        nfsd4_close_open_stateid(stp);
        mutex_unlock(&stp->st_mutex);

        /* v4.1+ suggests that we send a special stateid in here, since the
         * clients should just ignore this anyway. Since this is not useful
         * for v4.0 clients either, we set it to the special close_stateid
         * universally.
         *
         * See RFC5661 section 18.2.4, and RFC7530 section 16.2.5
         */
        memcpy(&close->cl_stateid, &close_stateid, sizeof(close->cl_stateid));

        /* 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,
                  union nfsd4_op_u *u)
{
        struct nfsd4_delegreturn *dr = &u->delegreturn;
        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 = nfsd4_stid_check_stateid_generation(stateid, &dp->dl_stid, nfsd4_has_session(cstate));
        if (status)
                goto put_stateid;

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

/* 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;
}

static fl_owner_t
nfsd4_fl_get_owner(fl_owner_t owner)
{
        struct nfs4_lockowner *lo = (struct nfs4_lockowner *)owner;

        nfs4_get_stateowner(&lo->lo_owner);
        return owner;
}

static void
nfsd4_fl_put_owner(fl_owner_t owner)
{
        struct nfs4_lockowner *lo = (struct nfs4_lockowner *)owner;

        if (lo)
                nfs4_put_stateowner(&lo->lo_owner);
}

static void
nfsd4_lm_notify(struct file_lock *fl)
{
        struct nfs4_lockowner           *lo = (struct nfs4_lockowner *)fl->fl_owner;
        struct net                      *net = lo->lo_owner.so_client->net;
        struct nfsd_net                 *nn = net_generic(net, nfsd_net_id);
        struct nfsd4_blocked_lock       *nbl = container_of(fl,
                                                struct nfsd4_blocked_lock, nbl_lock);
        bool queue = false;

        /* An empty list means that something else is going to be using it */
        spin_lock(&nn->blocked_locks_lock);
        if (!list_empty(&nbl->nbl_list)) {
                list_del_init(&nbl->nbl_list);
                list_del_init(&nbl->nbl_lru);
                queue = true;
        }
        spin_unlock(&nn->blocked_locks_lock);

        if (queue) {
                trace_nfsd_cb_notify_lock(lo, nbl);
                nfsd4_run_cb(&nbl->nbl_cb);
        }
}

static const struct lock_manager_operations nfsd_posix_mng_ops  = {
        .lm_notify = nfsd4_lm_notify,
        .lm_get_owner = nfsd4_fl_get_owner,
        .lm_put_owner = nfsd4_fl_put_owner,
};

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;
                xdr_netobj_dup(&deny->ld_owner, &lo->lo_owner.so_owner,
                                                GFP_KERNEL);
                if (!deny->ld_owner.data)
                        /* We just don't care that much */
                        goto nevermind;
                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(struct nfs4_client *clp, struct xdr_netobj *owner)
{
        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))
                        return lockowner(nfs4_get_stateowner(so));
        }
        return NULL;
}

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

        spin_lock(&clp->cl_lock);
        lo = find_lockowner_str_locked(clp, owner);
        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_blocked);
        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, &lock->lk_new_owner);
        if (ret == NULL) {
                list_add(&lo->lo_owner.so_strhash,
                         &clp->cl_ownerstr_hashtbl[strhashval]);
                ret = lo;
        } else
                nfs4_free_stateowner(&lo->lo_owner);

        spin_unlock(&clp->cl_lock);
        return ret;
}

static struct nfs4_ol_stateid *
find_lock_stateid(const struct nfs4_lockowner *lo,
                  const struct nfs4_ol_stateid *ost)
{
        struct nfs4_ol_stateid *lst;

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

        /* If ost is not hashed, ost->st_locks will not be valid */
        if (!nfs4_ol_stateid_unhashed(ost))
                list_for_each_entry(lst, &ost->st_locks, st_locks) {
                        if (lst->st_stateowner == &lo->lo_owner) {
                                refcount_inc(&lst->st_stid.sc_count);
                                return lst;
                        }
                }
        return NULL;
}

static struct nfs4_ol_stateid *
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;
        struct nfs4_ol_stateid *retstp;

        mutex_init(&stp->st_mutex);
        mutex_lock_nested(&stp->st_mutex, OPEN_STATEID_MUTEX);
retry:
        spin_lock(&clp->cl_lock);
        if (nfs4_ol_stateid_unhashed(open_stp))
                goto out_close;
        retstp = find_lock_stateid(lo, open_stp);
        if (retstp)
                goto out_found;
        refcount_inc(&stp->st_stid.sc_count);
        stp->st_stid.sc_type = NFS4_LOCK_STID;
        stp->st_stateowner = nfs4_get_stateowner(&lo->lo_owner);
        get_nfs4_file(fp);
        stp->st_stid.sc_file = fp;
        stp->st_access_bmap = 0;
        stp->st_deny_bmap = open_stp->st_deny_bmap;
        stp->st_openstp = open_stp;
        spin_lock(&fp->fi_lock);
        list_add(&stp->st_locks, &open_stp->st_locks);
        list_add(&stp->st_perstateowner, &lo->lo_owner.so_stateids);
        list_add(&stp->st_perfile, &fp->fi_stateids);
        spin_unlock(&fp->fi_lock);
        spin_unlock(&clp->cl_lock);
        return stp;
out_found:
        spin_unlock(&clp->cl_lock);
        if (nfsd4_lock_ol_stateid(retstp) != nfs_ok) {
                nfs4_put_stid(&retstp->st_stid);
                goto retry;
        }
        /* To keep mutex tracking happy */
        mutex_unlock(&stp->st_mutex);
        return retstp;
out_close:
        spin_unlock(&clp->cl_lock);
        mutex_unlock(&stp->st_mutex);
        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;

        *new = false;
        spin_lock(&clp->cl_lock);
        lst = find_lock_stateid(lo, ost);
        spin_unlock(&clp->cl_lock);
        if (lst != NULL) {
                if (nfsd4_lock_ol_stateid(lst) == nfs_ok)
                        goto out;
                nfs4_put_stid(&lst->st_stid);
        }
        ns = nfs4_alloc_stid(clp, stateid_slab, nfs4_free_lock_stateid);
        if (ns == NULL)
                return NULL;

        lst = init_lock_stateid(openlockstateid(ns), lo, fi, inode, ost);
        if (lst == openlockstateid(ns))
                *new = true;
        else
                nfs4_put_stid(ns);
out:
        return lst;
}

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

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 **plst, 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 = d_inode(cstate->current_fh.fh_dentry);
        struct nfs4_lockowner *lo;
        struct nfs4_ol_stateid *lst;
        unsigned int strhashval;

        lo = find_lockowner_str(cl, &lock->lk_new_owner);
        if (!lo) {
                strhashval = ownerstr_hashval(&lock->lk_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;
        *plst = lst;
out:
        nfs4_put_stateowner(&lo->lo_owner);
        return status;
}

/*
 *  LOCK operation 
 */
__be32
nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
           union nfsd4_op_u *u)
{
        struct nfsd4_lock *lock = &u->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 nfsd_file *nf = NULL;
        struct nfsd4_blocked_lock *nbl = NULL;
        struct file_lock *file_lock = NULL;
        struct file_lock *conflock = NULL;
        __be32 status = 0;
        int lkflg;
        int err;
        bool new = false;
        unsigned char fl_type;
        unsigned int fl_flags = FL_POSIX;
        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->lk_new_clientid,
                                &cstate->clp->cl_clientid,
                                sizeof(clientid_t));

                /* 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;
                mutex_unlock(&open_stp->st_mutex);
                open_sop = openowner(open_stp->st_stateowner);
                status = nfserr_bad_stateid;
                if (!same_clid(&open_sop->oo_owner.so_client->cl_clientid,
                                                &lock->lk_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;

        if (lock->lk_reclaim)
                fl_flags |= FL_RECLAIM;

        fp = lock_stp->st_stid.sc_file;
        switch (lock->lk_type) {
                case NFS4_READW_LT:
                        if (nfsd4_has_session(cstate))
                                fl_flags |= FL_SLEEP;
                        fallthrough;
                case NFS4_READ_LT:
                        spin_lock(&fp->fi_lock);
                        nf = find_readable_file_locked(fp);
                        if (nf)
                                get_lock_access(lock_stp, NFS4_SHARE_ACCESS_READ);
                        spin_unlock(&fp->fi_lock);
                        fl_type = F_RDLCK;
                        break;
                case NFS4_WRITEW_LT:
                        if (nfsd4_has_session(cstate))
                                fl_flags |= FL_SLEEP;
                        fallthrough;
                case NFS4_WRITE_LT:
                        spin_lock(&fp->fi_lock);
                        nf = find_writeable_file_locked(fp);
                        if (nf)
                                get_lock_access(lock_stp, NFS4_SHARE_ACCESS_WRITE);
                        spin_unlock(&fp->fi_lock);
                        fl_type = F_WRLCK;
                        break;
                default:
                        status = nfserr_inval;
                goto out;
        }

        if (!nf) {
                status = nfserr_openmode;
                goto out;
        }

        /*
         * Most filesystems with their own ->lock operations will block
         * the nfsd thread waiting to acquire the lock.  That leads to
         * deadlocks (we don't want every nfsd thread tied up waiting
         * for file locks), so don't attempt blocking lock notifications
         * on those filesystems:
         */
        if (nf->nf_file->f_op->lock)
                fl_flags &= ~FL_SLEEP;

        nbl = find_or_allocate_block(lock_sop, &fp->fi_fhandle, nn);
        if (!nbl) {
                dprintk("NFSD: %s: unable to allocate block!\n", __func__);
                status = nfserr_jukebox;
                goto out;
        }

        file_lock = &nbl->nbl_lock;
        file_lock->fl_type = fl_type;
        file_lock->fl_owner = (fl_owner_t)lockowner(nfs4_get_stateowner(&lock_sop->lo_owner));
        file_lock->fl_pid = current->tgid;
        file_lock->fl_file = nf->nf_file;
        file_lock->fl_flags = fl_flags;
        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;
        }

        if (fl_flags & FL_SLEEP) {
                nbl->nbl_time = ktime_get_boottime_seconds();
                spin_lock(&nn->blocked_locks_lock);
                list_add_tail(&nbl->nbl_list, &lock_sop->lo_blocked);
                list_add_tail(&nbl->nbl_lru, &nn->blocked_locks_lru);
                kref_get(&nbl->nbl_kref);
                spin_unlock(&nn->blocked_locks_lock);
        }

        err = vfs_lock_file(nf->nf_file, F_SETLK, file_lock, conflock);
        switch (err) {
        case 0: /* success! */
                nfs4_inc_and_copy_stateid(&lock->lk_resp_stateid, &lock_stp->st_stid);
                status = 0;
                if (lock->lk_reclaim)
                        nn->somebody_reclaimed = true;
                break;
        case FILE_LOCK_DEFERRED:
                kref_put(&nbl->nbl_kref, free_nbl);
                nbl = NULL;
                fallthrough;
        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 (nbl) {
                /* dequeue it if we queued it before */
                if (fl_flags & FL_SLEEP) {
                        spin_lock(&nn->blocked_locks_lock);
                        if (!list_empty(&nbl->nbl_list) &&
                            !list_empty(&nbl->nbl_lru)) {
                                list_del_init(&nbl->nbl_list);
                                list_del_init(&nbl->nbl_lru);
                                kref_put(&nbl->nbl_kref, free_nbl);
                        }
                        /* nbl can use one of lists to be linked to reaplist */
                        spin_unlock(&nn->blocked_locks_lock);
                }
                free_blocked_lock(nbl);
        }
        if (nf)
                nfsd_file_put(nf);
        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);

                mutex_unlock(&lock_stp->st_mutex);

                nfs4_put_stid(&lock_stp->st_stid);
        }
        if (open_stp)
                nfs4_put_stid(&open_stp->st_stid);
        nfsd4_bump_seqid(cstate, status);
        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.
 */
static __be32 nfsd_test_lock(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file_lock *lock)
{
        struct nfsd_file *nf;
        __be32 err;

        err = nfsd_file_acquire(rqstp, fhp, NFSD_MAY_READ, &nf);
        if (err)
                return err;
        fh_lock(fhp); /* to block new leases till after test_lock: */
        err = nfserrno(nfsd_open_break_lease(fhp->fh_dentry->d_inode,
                                                        NFSD_MAY_READ));
        if (err)
                goto out;
        lock->fl_file = nf->nf_file;
        err = nfserrno(vfs_test_lock(nf->nf_file, lock));
        lock->fl_file = NULL;
out:
        fh_unlock(fhp);
        nfsd_file_put(nf);
        return err;
}

/*
 * LOCKT operation
 */
__be32
nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
            union nfsd4_op_u *u)
{
        struct nfsd4_lockt *lockt = &u->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 = set_client(&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(cstate->clp, &lockt->lt_owner);
        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,
            union nfsd4_op_u *u)
{
        struct nfsd4_locku *locku = &u->locku;
        struct nfs4_ol_stateid *stp;
        struct nfsd_file *nf = 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;
        nf = find_any_file(stp->st_stid.sc_file);
        if (!nf) {
                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 put_file;
        }

        file_lock->fl_type = F_UNLCK;
        file_lock->fl_owner = (fl_owner_t)lockowner(nfs4_get_stateowner(stp->st_stateowner));
        file_lock->fl_pid = current->tgid;
        file_lock->fl_file = nf->nf_file;
        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(nf->nf_file, F_SETLK, file_lock, NULL);
        if (err) {
                dprintk("NFSD: nfs4_locku: vfs_lock_file failed!\n");
                goto out_nfserr;
        }
        nfs4_inc_and_copy_stateid(&locku->lu_stateid, &stp->st_stid);
put_file:
        nfsd_file_put(nf);
put_stateid:
        mutex_unlock(&stp->st_mutex);
        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 put_file;
}

/*
 * 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 *fl;
        int status = false;
        struct nfsd_file *nf = find_any_file(fp);
        struct inode *inode;
        struct file_lock_context *flctx;

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

        inode = locks_inode(nf->nf_file);
        flctx = inode->i_flctx;

        if (flctx && !list_empty_careful(&flctx->flc_posix)) {
                spin_lock(&flctx->flc_lock);
                list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
                        if (fl->fl_owner == (fl_owner_t)lowner) {
                                status = true;
                                break;
                        }
                }
                spin_unlock(&flctx->flc_lock);
        }
        nfsd_file_put(nf);
        return status;
}

__be32
nfsd4_release_lockowner(struct svc_rqst *rqstp,
                        struct nfsd4_compound_state *cstate,
                        union nfsd4_op_u *u)
{
        struct nfsd4_release_lockowner *rlockowner = &u->release_lockowner;
        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;
        LIST_HEAD (reaplist);

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

        status = set_client(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;
                        }
                }

                nfs4_get_stateowner(sop);
                break;
        }
        if (!lo) {
                spin_unlock(&clp->cl_lock);
                return status;
        }

        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);
                WARN_ON(!unhash_lock_stateid(stp));
                put_ol_stateid_locked(stp, &reaplist);
        }
        spin_unlock(&clp->cl_lock);
        free_ol_stateid_reaplist(&reaplist);
        remove_blocked_locks(lo);
        nfs4_put_stateowner(&lo->lo_owner);

        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(struct xdr_netobj 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...
 *
 * The caller is responsible for freeing name.data if NULL is returned (it
 * will be freed in nfs4_remove_reclaim_record in the normal case).
 */
struct nfs4_client_reclaim *
nfs4_client_to_reclaim(struct xdr_netobj name, struct xdr_netobj princhash,
                struct nfsd_net *nn)
{
        unsigned int strhashval;
        struct nfs4_client_reclaim *crp;

        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]);
                crp->cr_name.data = name.data;
                crp->cr_name.len = name.len;
                crp->cr_princhash.data = princhash.data;
                crp->cr_princhash.len = princhash.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->cr_name.data);
        kfree(crp->cr_princhash.data);
        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(struct xdr_netobj name, struct nfsd_net *nn)
{
        unsigned int strhashval;
        struct nfs4_client_reclaim *crp = NULL;

        strhashval = clientstr_hashval(name);
        list_for_each_entry(crp, &nn->reclaim_str_hashtbl[strhashval], cr_strhash) {
                if (compare_blob(&crp->cr_name, &name) == 0) {
                        return crp;
                }
        }
        return NULL;
}

__be32
nfs4_check_open_reclaim(struct nfs4_client *clp)
{
        if (test_bit(NFSD4_CLIENT_RECLAIM_COMPLETE, &clp->cl_flags))
                return nfserr_no_grace;

        if (nfsd4_client_record_check(clp))
                return nfserr_reclaim_bad;

        return nfs_ok;
}

/*
 * 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_array(CLIENT_HASH_SIZE,
                                            sizeof(struct list_head),
                                            GFP_KERNEL);
        if (!nn->conf_id_hashtbl)
                goto err;
        nn->unconf_id_hashtbl = kmalloc_array(CLIENT_HASH_SIZE,
                                              sizeof(struct list_head),
                                              GFP_KERNEL);
        if (!nn->unconf_id_hashtbl)
                goto err_unconf_id;
        nn->sessionid_hashtbl = kmalloc_array(SESSION_HASH_SIZE,
                                              sizeof(struct list_head),
                                              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;
        nn->boot_time = ktime_get_real_seconds();
        nn->grace_ended = false;
        nn->nfsd4_manager.block_opens = true;
        INIT_LIST_HEAD(&nn->nfsd4_manager.list);
        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);
        spin_lock_init(&nn->s2s_cp_lock);
        idr_init(&nn->s2s_cp_stateids);

        spin_lock_init(&nn->blocked_locks_lock);
        INIT_LIST_HEAD(&nn->blocked_locks_lru);

        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);
                }
        }

        WARN_ON(!list_empty(&nn->blocked_locks_lru));

        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;
        locks_start_grace(net, &nn->nfsd4_manager);
        nfsd4_client_tracking_init(net);
        if (nn->track_reclaim_completes && nn->reclaim_str_hashtbl_size == 0)
                goto skip_grace;
        printk(KERN_INFO "NFSD: starting %lld-second grace period (net %x)\n",
               nn->nfsd4_grace, net->ns.inum);
        trace_nfsd_grace_start(nn);
        queue_delayed_work(laundry_wq, &nn->laundromat_work, nn->nfsd4_grace * HZ);
        return 0;

skip_grace:
        printk(KERN_INFO "NFSD: no clients to reclaim, skipping NFSv4 grace period (net %x)\n",
                        net->ns.inum);
        queue_delayed_work(laundry_wq, &nn->laundromat_work, nn->nfsd4_lease * HZ);
        nfsd4_end_grace(nn);
        return 0;
}

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

int
nfs4_state_start(void)
{
        int ret;

        laundry_wq = alloc_workqueue("%s", WQ_UNBOUND, 0, "nfsd4");
        if (laundry_wq == NULL) {
                ret = -ENOMEM;
                goto out;
        }
        ret = nfsd4_create_callback_queue();
        if (ret)
                goto out_free_laundry;

        set_max_delegations();
        return 0;

out_free_laundry:
        destroy_workqueue(laundry_wq);
out:
        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);
                WARN_ON(!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);
                destroy_unhashed_deleg(dp);
        }

        nfsd4_client_tracking_exit(net);
        nfs4_state_destroy_net(net);
#ifdef CONFIG_NFSD_V4_2_INTER_SSC
        nfsd4_ssc_shutdown_umount(nn);
#endif
}

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_CSTATE_FLAG(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_CSTATE_FLAG(cstate, CURRENT_STATE_ID_FLAG);
        }
}

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

/*
 * functions to set current state id
 */
void
nfsd4_set_opendowngradestateid(struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        put_stateid(cstate, &u->open_downgrade.od_stateid);
}

void
nfsd4_set_openstateid(struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        put_stateid(cstate, &u->open.op_stateid);
}

void
nfsd4_set_closestateid(struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        put_stateid(cstate, &u->close.cl_stateid);
}

void
nfsd4_set_lockstateid(struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        put_stateid(cstate, &u->lock.lk_resp_stateid);
}

/*
 * functions to consume current state id
 */

void
nfsd4_get_opendowngradestateid(struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        get_stateid(cstate, &u->open_downgrade.od_stateid);
}

void
nfsd4_get_delegreturnstateid(struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        get_stateid(cstate, &u->delegreturn.dr_stateid);
}

void
nfsd4_get_freestateid(struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        get_stateid(cstate, &u->free_stateid.fr_stateid);
}

void
nfsd4_get_setattrstateid(struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        get_stateid(cstate, &u->setattr.sa_stateid);
}

void
nfsd4_get_closestateid(struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        get_stateid(cstate, &u->close.cl_stateid);
}

void
nfsd4_get_lockustateid(struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        get_stateid(cstate, &u->locku.lu_stateid);
}

void
nfsd4_get_readstateid(struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        get_stateid(cstate, &u->read.rd_stateid);
}

void
nfsd4_get_writestateid(struct nfsd4_compound_state *cstate,
                union nfsd4_op_u *u)
{
        get_stateid(cstate, &u->write.wr_stateid);
}