nfsd4: allow an EXCHANGE_ID to kill a 4.0 client

[mirror_ubuntu-artful-kernel.git] / fs / nfsd / nfs4state.c

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

#include <linux/file.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/clnt.h>
#include "xdr4.h"
#include "vfs.h"
#include "current_stateid.h"

#define NFSDDBG_FACILITY                NFSDDBG_PROC

/* Globals */
time_t nfsd4_lease = 90;     /* default lease time */
time_t nfsd4_grace = 90;
static time_t boot_time;

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

static u64 current_sessionid = 1;

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

/* forward declarations */
static int check_for_locks(struct nfs4_file *filp, struct nfs4_lockowner *lowner);

/* Locking: */

/* Currently used for almost all code touching nfsv4 state: */
static DEFINE_MUTEX(client_mutex);

/*
 * 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(recall_lock);

static struct kmem_cache *openowner_slab = NULL;
static struct kmem_cache *lockowner_slab = NULL;
static struct kmem_cache *file_slab = NULL;
static struct kmem_cache *stateid_slab = NULL;
static struct kmem_cache *deleg_slab = NULL;

void
nfs4_lock_state(void)
{
        mutex_lock(&client_mutex);
}

static void free_session(struct kref *);

/* Must be called under the client_lock */
static void nfsd4_put_session_locked(struct nfsd4_session *ses)
{
        kref_put(&ses->se_ref, free_session);
}

static void nfsd4_get_session(struct nfsd4_session *ses)
{
        kref_get(&ses->se_ref);
}

void
nfs4_unlock_state(void)
{
        mutex_unlock(&client_mutex);
}

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 struct list_head del_recall_lru;

static void nfsd4_free_file(struct nfs4_file *f)
{
        kmem_cache_free(file_slab, f);
}

static inline void
put_nfs4_file(struct nfs4_file *fi)
{
        if (atomic_dec_and_lock(&fi->fi_ref, &recall_lock)) {
                list_del(&fi->fi_hash);
                spin_unlock(&recall_lock);
                iput(fi->fi_inode);
                nfsd4_free_file(fi);
        }
}

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

static int num_delegations;
unsigned int 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(u32 clientid, struct xdr_netobj *ownername)
{
        unsigned int ret;

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

static struct list_head ownerstr_hashtbl[OWNER_HASH_SIZE];

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

static unsigned int file_hashval(struct inode *ino)
{
        /* XXX: why are we hashing on inode pointer, anyway? */
        return hash_ptr(ino, FILE_HASH_BITS);
}

static struct list_head file_hashtbl[FILE_HASH_SIZE];

static void __nfs4_file_get_access(struct nfs4_file *fp, int oflag)
{
        BUG_ON(!(fp->fi_fds[oflag] || fp->fi_fds[O_RDWR]));
        atomic_inc(&fp->fi_access[oflag]);
}

static void nfs4_file_get_access(struct nfs4_file *fp, int oflag)
{
        if (oflag == O_RDWR) {
                __nfs4_file_get_access(fp, O_RDONLY);
                __nfs4_file_get_access(fp, O_WRONLY);
        } else
                __nfs4_file_get_access(fp, oflag);
}

static void nfs4_file_put_fd(struct nfs4_file *fp, int oflag)
{
        if (fp->fi_fds[oflag]) {
                fput(fp->fi_fds[oflag]);
                fp->fi_fds[oflag] = NULL;
        }
}

static void __nfs4_file_put_access(struct nfs4_file *fp, int oflag)
{
        if (atomic_dec_and_test(&fp->fi_access[oflag])) {
                nfs4_file_put_fd(fp, oflag);
                /*
                 * It's also safe to get rid of the RDWR open *if*
                 * we no longer have need of the other kind of access
                 * or if we already have the other kind of open:
                 */
                if (fp->fi_fds[1-oflag]
                        || atomic_read(&fp->fi_access[1 - oflag]) == 0)
                        nfs4_file_put_fd(fp, O_RDWR);
        }
}

static void nfs4_file_put_access(struct nfs4_file *fp, int oflag)
{
        if (oflag == O_RDWR) {
                __nfs4_file_put_access(fp, O_RDONLY);
                __nfs4_file_put_access(fp, O_WRONLY);
        } else
                __nfs4_file_put_access(fp, oflag);
}

static inline int get_new_stid(struct nfs4_stid *stid)
{
        static int min_stateid = 0;
        struct idr *stateids = &stid->sc_client->cl_stateids;
        int new_stid;
        int error;

        error = idr_get_new_above(stateids, stid, min_stateid, &new_stid);
        /*
         * Note: the necessary preallocation was done in
         * nfs4_alloc_stateid().  The idr code caps the number of
         * preallocations that can exist at a time, but the state lock
         * prevents anyone from using ours before we get here:
         */
        BUG_ON(error);
        /*
         * 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):
         */

        min_stateid = new_stid+1;
        if (min_stateid == INT_MAX)
                min_stateid = 0;
        return new_stid;
}

static void init_stid(struct nfs4_stid *stid, struct nfs4_client *cl, unsigned char type)
{
        stateid_t *s = &stid->sc_stateid;
        int new_id;

        stid->sc_type = type;
        stid->sc_client = cl;
        s->si_opaque.so_clid = cl->cl_clientid;
        new_id = get_new_stid(stid);
        s->si_opaque.so_id = (u32)new_id;
        /* Will be incremented before return to client: */
        s->si_generation = 0;
}

static struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl, struct kmem_cache *slab)
{
        struct idr *stateids = &cl->cl_stateids;

        if (!idr_pre_get(stateids, GFP_KERNEL))
                return NULL;
        /*
         * Note: if we fail here (or any time between now and the time
         * we actually get the new idr), we won't need to undo the idr
         * preallocation, since the idr code caps the number of
         * preallocated entries.
         */
        return kmem_cache_alloc(slab, GFP_KERNEL);
}

static struct nfs4_ol_stateid * nfs4_alloc_stateid(struct nfs4_client *clp)
{
        return openlockstateid(nfs4_alloc_stid(clp, stateid_slab));
}

static struct nfs4_delegation *
alloc_init_deleg(struct nfs4_client *clp, struct nfs4_ol_stateid *stp, struct svc_fh *current_fh, u32 type)
{
        struct nfs4_delegation *dp;
        struct nfs4_file *fp = stp->st_file;

        dprintk("NFSD alloc_init_deleg\n");
        /*
         * Major work on the lease subsystem (for example, to support
         * calbacks on stat) will be required before we can support
         * write delegations properly.
         */
        if (type != NFS4_OPEN_DELEGATE_READ)
                return NULL;
        if (fp->fi_had_conflict)
                return NULL;
        if (num_delegations > max_delegations)
                return NULL;
        dp = delegstateid(nfs4_alloc_stid(clp, deleg_slab));
        if (dp == NULL)
                return dp;
        init_stid(&dp->dl_stid, clp, NFS4_DELEG_STID);
        /*
         * 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;
        num_delegations++;
        INIT_LIST_HEAD(&dp->dl_perfile);
        INIT_LIST_HEAD(&dp->dl_perclnt);
        INIT_LIST_HEAD(&dp->dl_recall_lru);
        get_nfs4_file(fp);
        dp->dl_file = fp;
        dp->dl_type = type;
        fh_copy_shallow(&dp->dl_fh, &current_fh->fh_handle);
        dp->dl_time = 0;
        atomic_set(&dp->dl_count, 1);
        INIT_WORK(&dp->dl_recall.cb_work, nfsd4_do_callback_rpc);
        return dp;
}

void
nfs4_put_delegation(struct nfs4_delegation *dp)
{
        if (atomic_dec_and_test(&dp->dl_count)) {
                dprintk("NFSD: freeing dp %p\n",dp);
                put_nfs4_file(dp->dl_file);
                kmem_cache_free(deleg_slab, dp);
                num_delegations--;
        }
}

static void nfs4_put_deleg_lease(struct nfs4_file *fp)
{
        if (atomic_dec_and_test(&fp->fi_delegees)) {
                vfs_setlease(fp->fi_deleg_file, F_UNLCK, &fp->fi_lease);
                fp->fi_lease = NULL;
                fput(fp->fi_deleg_file);
                fp->fi_deleg_file = NULL;
        }
}

static void unhash_stid(struct nfs4_stid *s)
{
        struct idr *stateids = &s->sc_client->cl_stateids;

        idr_remove(stateids, s->sc_stateid.si_opaque.so_id);
}

/* Called under the state lock. */
static void
unhash_delegation(struct nfs4_delegation *dp)
{
        unhash_stid(&dp->dl_stid);
        list_del_init(&dp->dl_perclnt);
        spin_lock(&recall_lock);
        list_del_init(&dp->dl_perfile);
        list_del_init(&dp->dl_recall_lru);
        spin_unlock(&recall_lock);
        nfs4_put_deleg_lease(dp->dl_file);
        nfs4_put_delegation(dp);
}

/* 
 * SETCLIENTID state 
 */

/* client_lock protects the client lru list and session hash table */
static DEFINE_SPINLOCK(client_lock);

/* Hash tables for nfs4_clientid state */
#define CLIENT_HASH_BITS                 4
#define CLIENT_HASH_SIZE                (1 << CLIENT_HASH_BITS)
#define CLIENT_HASH_MASK                (CLIENT_HASH_SIZE - 1)

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

static unsigned int clientstr_hashval(const char *name)
{
        return opaque_hashval(name, 8) & CLIENT_HASH_MASK;
}

/*
 * reclaim_str_hashtbl[] holds known client info from previous reset/reboot
 * used in reboot/reset lease grace period processing
 *
 * conf_id_hashtbl[], and conf_str_hashtbl[] hold confirmed
 * setclientid_confirmed info. 
 *
 * unconf_str_hastbl[] and unconf_id_hashtbl[] hold unconfirmed 
 * setclientid info.
 *
 * client_lru holds client queue ordered by nfs4_client.cl_time
 * for lease renewal.
 *
 * close_lru holds (open) stateowner queue ordered by nfs4_stateowner.so_time
 * for last close replay.
 */
static struct list_head reclaim_str_hashtbl[CLIENT_HASH_SIZE];
static int reclaim_str_hashtbl_size = 0;
static struct list_head conf_id_hashtbl[CLIENT_HASH_SIZE];
static struct list_head conf_str_hashtbl[CLIENT_HASH_SIZE];
static struct list_head unconf_str_hashtbl[CLIENT_HASH_SIZE];
static struct list_head unconf_id_hashtbl[CLIENT_HASH_SIZE];
static struct list_head client_lru;
static struct list_head close_lru;

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

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

static bool
test_share(struct nfs4_ol_stateid *stp, struct nfsd4_open *open) {
        unsigned int access, deny;

        access = bmap_to_share_mode(stp->st_access_bmap);
        deny = bmap_to_share_mode(stp->st_deny_bmap);
        if ((access & open->op_share_deny) || (deny & open->op_share_access))
                return false;
        return true;
}

/* set share access for a given stateid */
static inline void
set_access(u32 access, struct nfs4_ol_stateid *stp)
{
        __set_bit(access, &stp->st_access_bmap);
}

/* clear share access for a given stateid */
static inline void
clear_access(u32 access, struct nfs4_ol_stateid *stp)
{
        __clear_bit(access, &stp->st_access_bmap);
}

/* test whether a given stateid has access */
static inline bool
test_access(u32 access, struct nfs4_ol_stateid *stp)
{
        return test_bit(access, &stp->st_access_bmap);
}

/* set share deny for a given stateid */
static inline void
set_deny(u32 access, struct nfs4_ol_stateid *stp)
{
        __set_bit(access, &stp->st_deny_bmap);
}

/* clear share deny for a given stateid */
static inline void
clear_deny(u32 access, struct nfs4_ol_stateid *stp)
{
        __clear_bit(access, &stp->st_deny_bmap);
}

/* test whether a given stateid is denying specific access */
static inline bool
test_deny(u32 access, struct nfs4_ol_stateid *stp)
{
        return test_bit(access, &stp->st_deny_bmap);
}

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;
        }
        BUG();
}

/* release all access and file references for a given stateid */
static void
release_all_access(struct nfs4_ol_stateid *stp)
{
        int i;

        for (i = 1; i < 4; i++) {
                if (test_access(i, stp))
                        nfs4_file_put_access(stp->st_file,
                                             nfs4_access_to_omode(i));
                clear_access(i, stp);
        }
}

static void unhash_generic_stateid(struct nfs4_ol_stateid *stp)
{
        list_del(&stp->st_perfile);
        list_del(&stp->st_perstateowner);
}

static void close_generic_stateid(struct nfs4_ol_stateid *stp)
{
        release_all_access(stp);
        put_nfs4_file(stp->st_file);
        stp->st_file = NULL;
}

static void free_generic_stateid(struct nfs4_ol_stateid *stp)
{
        kmem_cache_free(stateid_slab, stp);
}

static void release_lock_stateid(struct nfs4_ol_stateid *stp)
{
        struct file *file;

        unhash_generic_stateid(stp);
        unhash_stid(&stp->st_stid);
        file = find_any_file(stp->st_file);
        if (file)
                locks_remove_posix(file, (fl_owner_t)lockowner(stp->st_stateowner));
        close_generic_stateid(stp);
        free_generic_stateid(stp);
}

static void unhash_lockowner(struct nfs4_lockowner *lo)
{
        struct nfs4_ol_stateid *stp;

        list_del(&lo->lo_owner.so_strhash);
        list_del(&lo->lo_perstateid);
        list_del(&lo->lo_owner_ino_hash);
        while (!list_empty(&lo->lo_owner.so_stateids)) {
                stp = list_first_entry(&lo->lo_owner.so_stateids,
                                struct nfs4_ol_stateid, st_perstateowner);
                release_lock_stateid(stp);
        }
}

static void release_lockowner(struct nfs4_lockowner *lo)
{
        unhash_lockowner(lo);
        nfs4_free_lockowner(lo);
}

static void
release_stateid_lockowners(struct nfs4_ol_stateid *open_stp)
{
        struct nfs4_lockowner *lo;

        while (!list_empty(&open_stp->st_lockowners)) {
                lo = list_entry(open_stp->st_lockowners.next,
                                struct nfs4_lockowner, lo_perstateid);
                release_lockowner(lo);
        }
}

static void unhash_open_stateid(struct nfs4_ol_stateid *stp)
{
        unhash_generic_stateid(stp);
        release_stateid_lockowners(stp);
        close_generic_stateid(stp);
}

static void release_open_stateid(struct nfs4_ol_stateid *stp)
{
        unhash_open_stateid(stp);
        unhash_stid(&stp->st_stid);
        free_generic_stateid(stp);
}

static void unhash_openowner(struct nfs4_openowner *oo)
{
        struct nfs4_ol_stateid *stp;

        list_del(&oo->oo_owner.so_strhash);
        list_del(&oo->oo_perclient);
        while (!list_empty(&oo->oo_owner.so_stateids)) {
                stp = list_first_entry(&oo->oo_owner.so_stateids,
                                struct nfs4_ol_stateid, st_perstateowner);
                release_open_stateid(stp);
        }
}

static void release_last_closed_stateid(struct nfs4_openowner *oo)
{
        struct nfs4_ol_stateid *s = oo->oo_last_closed_stid;

        if (s) {
                unhash_stid(&s->st_stid);
                free_generic_stateid(s);
                oo->oo_last_closed_stid = NULL;
        }
}

static void release_openowner(struct nfs4_openowner *oo)
{
        unhash_openowner(oo);
        list_del(&oo->oo_close_lru);
        release_last_closed_stateid(oo);
        nfs4_free_openowner(oo);
}

#define SESSION_HASH_SIZE       512
static struct list_head sessionid_hashtbl[SESSION_HASH_SIZE];

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

        return sid->sequence % SESSION_HASH_SIZE;
}

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


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

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

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

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

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

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

static int nfsd4_sanitize_slot_size(u32 size)
{
        size -= NFSD_MIN_HDR_SEQ_SZ; /* We don't cache the rpc header */
        size = min_t(u32, size, NFSD_SLOT_CACHE_SIZE);

        return size;
}

/*
 * 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 int nfsd4_get_drc_mem(int slotsize, u32 num)
{
        int avail;

        num = min_t(u32, num, NFSD_MAX_SLOTS_PER_SESSION);

        spin_lock(&nfsd_drc_lock);
        avail = min_t(int, NFSD_MAX_MEM_PER_SESSION,
                        nfsd_drc_max_mem - nfsd_drc_mem_used);
        num = min_t(int, num, avail / slotsize);
        nfsd_drc_mem_used += num * slotsize;
        spin_unlock(&nfsd_drc_lock);

        return num;
}

static void nfsd4_put_drc_mem(int slotsize, int num)
{
        spin_lock(&nfsd_drc_lock);
        nfsd_drc_mem_used -= slotsize * num;
        spin_unlock(&nfsd_drc_lock);
}

static struct nfsd4_session *alloc_session(int slotsize, int numslots)
{
        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++) {
                mem = sizeof(struct nfsd4_slot) + slotsize;
                new->se_slots[i] = kzalloc(mem, GFP_KERNEL);
                if (!new->se_slots[i])
                        goto out_free;
        }
        return new;
out_free:
        while (i--)
                kfree(new->se_slots[i]);
        kfree(new);
        return NULL;
}

static void init_forechannel_attrs(struct nfsd4_channel_attrs *new, struct nfsd4_channel_attrs *req, int numslots, int slotsize)
{
        u32 maxrpc = nfsd_serv->sv_max_mesg;

        new->maxreqs = numslots;
        new->maxresp_cached = min_t(u32, req->maxresp_cached,
                                        slotsize + NFSD_MIN_HDR_SEQ_SZ);
        new->maxreq_sz = min_t(u32, req->maxreq_sz, maxrpc);
        new->maxresp_sz = min_t(u32, req->maxresp_sz, maxrpc);
        new->maxops = min_t(u32, req->maxops, NFSD_MAX_OPS_PER_COMPOUND);
}

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

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

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

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 __be32 nfsd4_new_conn(struct svc_rqst *rqstp, struct nfsd4_session *ses, u32 dir)
{
        struct nfsd4_conn *conn;
        int ret;

        conn = alloc_conn(rqstp, dir);
        if (!conn)
                return nfserr_jukebox;
        nfsd4_hash_conn(conn, ses);
        ret = nfsd4_register_conn(conn);
        if (ret)
                /* oops; xprt is already down: */
                nfsd4_conn_lost(&conn->cn_xpt_user);
        return nfs_ok;
}

static __be32 nfsd4_new_conn_from_crses(struct svc_rqst *rqstp, struct nfsd4_session *ses)
{
        u32 dir = NFS4_CDFC4_FORE;

        if (ses->se_flags & SESSION4_BACK_CHAN)
                dir |= NFS4_CDFC4_BACK;

        return nfsd4_new_conn(rqstp, ses, 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 kref *kref)
{
        struct nfsd4_session *ses;
        int mem;

        BUG_ON(!spin_is_locked(&client_lock));
        ses = container_of(kref, struct nfsd4_session, se_ref);
        nfsd4_del_conns(ses);
        spin_lock(&nfsd_drc_lock);
        mem = ses->se_fchannel.maxreqs * slot_bytes(&ses->se_fchannel);
        nfsd_drc_mem_used -= mem;
        spin_unlock(&nfsd_drc_lock);
        free_session_slots(ses);
        kfree(ses);
}

void nfsd4_put_session(struct nfsd4_session *ses)
{
        spin_lock(&client_lock);
        nfsd4_put_session_locked(ses);
        spin_unlock(&client_lock);
}

static struct nfsd4_session *alloc_init_session(struct svc_rqst *rqstp, struct nfs4_client *clp, struct nfsd4_create_session *cses)
{
        struct nfsd4_session *new;
        struct nfsd4_channel_attrs *fchan = &cses->fore_channel;
        int numslots, slotsize;
        __be32 status;
        int idx;

        /*
         * 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.
         */
        slotsize = nfsd4_sanitize_slot_size(fchan->maxresp_cached);
        numslots = nfsd4_get_drc_mem(slotsize, fchan->maxreqs);
        if (numslots < 1)
                return NULL;

        new = alloc_session(slotsize, numslots);
        if (!new) {
                nfsd4_put_drc_mem(slotsize, fchan->maxreqs);
                return NULL;
        }
        init_forechannel_attrs(&new->se_fchannel, fchan, numslots, slotsize);

        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;
        kref_init(&new->se_ref);
        idx = hash_sessionid(&new->se_sessionid);
        spin_lock(&client_lock);
        list_add(&new->se_hash, &sessionid_hashtbl[idx]);
        spin_lock(&clp->cl_lock);
        list_add(&new->se_perclnt, &clp->cl_sessions);
        spin_unlock(&clp->cl_lock);
        spin_unlock(&client_lock);

        status = nfsd4_new_conn_from_crses(rqstp, new);
        /* whoops: benny points out, status is ignored! (err, or bogus) */
        if (status) {
                spin_lock(&client_lock);
                free_session(&new->se_ref);
                spin_unlock(&client_lock);
                return NULL;
        }
        if (cses->flags & SESSION4_BACK_CHAN) {
                struct sockaddr *sa = svc_addr(rqstp);
                /*
                 * This is a little silly; with sessions there's no real
                 * use for the callback address.  Use the peer address
                 * as a reasonable default for now, but consider fixing
                 * the rpc client not to require an address in the
                 * future:
                 */
                rpc_copy_addr((struct sockaddr *)&clp->cl_cb_conn.cb_addr, sa);
                clp->cl_cb_conn.cb_addrlen = svc_addr_len(sa);
        }
        nfsd4_probe_callback(clp);
        return new;
}

/* caller must hold client_lock */
static struct nfsd4_session *
find_in_sessionid_hashtbl(struct nfs4_sessionid *sessionid)
{
        struct nfsd4_session *elem;
        int idx;

        dump_sessionid(__func__, sessionid);
        idx = hash_sessionid(sessionid);
        /* Search in the appropriate list */
        list_for_each_entry(elem, &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;
}

/* caller must hold client_lock */
static void
unhash_session(struct nfsd4_session *ses)
{
        list_del(&ses->se_hash);
        spin_lock(&ses->se_client->cl_lock);
        list_del(&ses->se_perclnt);
        spin_unlock(&ses->se_client->cl_lock);
}

/* must be called under the client_lock */
static inline void
renew_client_locked(struct nfs4_client *clp)
{
        if (is_client_expired(clp)) {
                dprintk("%s: client (clientid %08x/%08x) already expired\n",
                        __func__,
                        clp->cl_clientid.cl_boot,
                        clp->cl_clientid.cl_id);
                return;
        }

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

static inline void
renew_client(struct nfs4_client *clp)
{
        spin_lock(&client_lock);
        renew_client_locked(clp);
        spin_unlock(&client_lock);
}

/* SETCLIENTID and SETCLIENTID_CONFIRM Helper functions */
static int
STALE_CLIENTID(clientid_t *clid)
{
        if (clid->cl_boot == boot_time)
                return 0;
        dprintk("NFSD stale clientid (%08x/%08x) boot_time %08lx\n",
                clid->cl_boot, clid->cl_id, boot_time);
        return 1;
}

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

        clp = kzalloc(sizeof(struct nfs4_client), GFP_KERNEL);
        if (clp == NULL)
                return NULL;
        clp->cl_name.data = kmemdup(name.data, name.len, GFP_KERNEL);
        if (clp->cl_name.data == NULL) {
                kfree(clp);
                return NULL;
        }
        clp->cl_name.len = name.len;
        return clp;
}

static inline void
free_client(struct nfs4_client *clp)
{
        BUG_ON(!spin_is_locked(&client_lock));
        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);
                nfsd4_put_session_locked(ses);
        }
        if (clp->cl_cred.cr_group_info)
                put_group_info(clp->cl_cred.cr_group_info);
        kfree(clp->cl_principal);
        kfree(clp->cl_name.data);
        kfree(clp);
}

void
release_session_client(struct nfsd4_session *session)
{
        struct nfs4_client *clp = session->se_client;

        if (!atomic_dec_and_lock(&clp->cl_refcount, &client_lock))
                return;
        if (is_client_expired(clp)) {
                free_client(clp);
                session->se_client = NULL;
        } else
                renew_client_locked(clp);
        spin_unlock(&client_lock);
}

/* must be called under the client_lock */
static inline void
unhash_client_locked(struct nfs4_client *clp)
{
        struct nfsd4_session *ses;

        mark_client_expired(clp);
        list_del(&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
expire_client(struct nfs4_client *clp)
{
        struct nfs4_openowner *oo;
        struct nfs4_delegation *dp;
        struct list_head reaplist;

        INIT_LIST_HEAD(&reaplist);
        spin_lock(&recall_lock);
        while (!list_empty(&clp->cl_delegations)) {
                dp = list_entry(clp->cl_delegations.next, struct nfs4_delegation, dl_perclnt);
                list_del_init(&dp->dl_perclnt);
                list_move(&dp->dl_recall_lru, &reaplist);
        }
        spin_unlock(&recall_lock);
        while (!list_empty(&reaplist)) {
                dp = list_entry(reaplist.next, struct nfs4_delegation, dl_recall_lru);
                unhash_delegation(dp);
        }
        while (!list_empty(&clp->cl_openowners)) {
                oo = list_entry(clp->cl_openowners.next, struct nfs4_openowner, oo_perclient);
                release_openowner(oo);
        }
        nfsd4_shutdown_callback(clp);
        if (clp->cl_cb_conn.cb_xprt)
                svc_xprt_put(clp->cl_cb_conn.cb_xprt);
        list_del(&clp->cl_idhash);
        list_del(&clp->cl_strhash);
        spin_lock(&client_lock);
        unhash_client_locked(clp);
        if (atomic_read(&clp->cl_refcount) == 0)
                free_client(clp);
        spin_unlock(&client_lock);
}

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 void copy_cred(struct svc_cred *target, struct svc_cred *source)
{
        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);
}

static int same_name(const char *n1, const char *n2)
{
        return 0 == memcmp(n1, n2, HEXDIR_LEN);
}

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

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

/* XXX what about NGROUP */
static int
same_creds(struct svc_cred *cr1, struct svc_cred *cr2)
{
        return cr1->cr_uid == cr2->cr_uid;
}

static void gen_clid(struct nfs4_client *clp)
{
        static u32 current_clientid = 1;

        clp->cl_clientid.cl_boot = boot_time;
        clp->cl_clientid.cl_id = current_clientid++; 
}

static void gen_confirm(struct nfs4_client *clp)
{
        __be32 verf[2];
        static u32 i;

        verf[0] = (__be32)get_seconds();
        verf[1] = (__be32)i++;
        memcpy(clp->cl_confirm.data, verf, sizeof(clp->cl_confirm.data));
}

static struct nfs4_stid *find_stateid(struct nfs4_client *cl, stateid_t *t)
{
        return idr_find(&cl->cl_stateids, t->si_opaque.so_id);
}

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

        s = find_stateid(cl, t);
        if (!s)
                return NULL;
        if (typemask & s->sc_type)
                return s;
        return NULL;
}

static struct nfs4_client *create_client(struct xdr_netobj name, char *recdir,
                struct svc_rqst *rqstp, nfs4_verifier *verf)
{
        struct nfs4_client *clp;
        struct sockaddr *sa = svc_addr(rqstp);
        char *princ;

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

        INIT_LIST_HEAD(&clp->cl_sessions);

        princ = svc_gss_principal(rqstp);
        if (princ) {
                clp->cl_principal = kstrdup(princ, GFP_KERNEL);
                if (clp->cl_principal == NULL) {
                        spin_lock(&client_lock);
                        free_client(clp);
                        spin_unlock(&client_lock);
                        return NULL;
                }
        }

        idr_init(&clp->cl_stateids);
        memcpy(clp->cl_recdir, recdir, HEXDIR_LEN);
        atomic_set(&clp->cl_refcount, 0);
        clp->cl_cb_state = NFSD4_CB_UNKNOWN;
        INIT_LIST_HEAD(&clp->cl_idhash);
        INIT_LIST_HEAD(&clp->cl_strhash);
        INIT_LIST_HEAD(&clp->cl_openowners);
        INIT_LIST_HEAD(&clp->cl_delegations);
        INIT_LIST_HEAD(&clp->cl_lru);
        INIT_LIST_HEAD(&clp->cl_callbacks);
        spin_lock_init(&clp->cl_lock);
        INIT_WORK(&clp->cl_cb_null.cb_work, nfsd4_do_callback_rpc);
        clp->cl_time = get_seconds();
        clear_bit(0, &clp->cl_cb_slot_busy);
        rpc_init_wait_queue(&clp->cl_cb_waitq, "Backchannel slot table");
        copy_verf(clp, verf);
        rpc_copy_addr((struct sockaddr *) &clp->cl_addr, sa);
        clp->cl_flavor = rqstp->rq_flavor;
        copy_cred(&clp->cl_cred, &rqstp->rq_cred);
        gen_confirm(clp);
        clp->cl_cb_session = NULL;
        return clp;
}

static void
add_to_unconfirmed(struct nfs4_client *clp, unsigned int strhashval)
{
        unsigned int idhashval;

        list_add(&clp->cl_strhash, &unconf_str_hashtbl[strhashval]);
        idhashval = clientid_hashval(clp->cl_clientid.cl_id);
        list_add(&clp->cl_idhash, &unconf_id_hashtbl[idhashval]);
        renew_client(clp);
}

static void
move_to_confirmed(struct nfs4_client *clp)
{
        unsigned int idhashval = clientid_hashval(clp->cl_clientid.cl_id);
        unsigned int strhashval;

        dprintk("NFSD: move_to_confirm nfs4_client %p\n", clp);
        list_move(&clp->cl_idhash, &conf_id_hashtbl[idhashval]);
        strhashval = clientstr_hashval(clp->cl_recdir);
        list_move(&clp->cl_strhash, &conf_str_hashtbl[strhashval]);
        renew_client(clp);
}

static struct nfs4_client *
find_confirmed_client(clientid_t *clid)
{
        struct nfs4_client *clp;
        unsigned int idhashval = clientid_hashval(clid->cl_id);

        list_for_each_entry(clp, &conf_id_hashtbl[idhashval], cl_idhash) {
                if (same_clid(&clp->cl_clientid, clid)) {
                        renew_client(clp);
                        return clp;
                }
        }
        return NULL;
}

static struct nfs4_client *
find_unconfirmed_client(clientid_t *clid)
{
        struct nfs4_client *clp;
        unsigned int idhashval = clientid_hashval(clid->cl_id);

        list_for_each_entry(clp, &unconf_id_hashtbl[idhashval], cl_idhash) {
                if (same_clid(&clp->cl_clientid, clid))
                        return clp;
        }
        return NULL;
}

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

static struct nfs4_client *
find_confirmed_client_by_str(const char *dname, unsigned int hashval)
{
        struct nfs4_client *clp;

        list_for_each_entry(clp, &conf_str_hashtbl[hashval], cl_strhash) {
                if (same_name(clp->cl_recdir, dname))
                        return clp;
        }
        return NULL;
}

static struct nfs4_client *
find_unconfirmed_client_by_str(const char *dname, unsigned int hashval)
{
        struct nfs4_client *clp;

        list_for_each_entry(clp, &unconf_str_hashtbl[hashval], cl_strhash) {
                if (same_name(clp->cl_recdir, dname))
                        return clp;
        }
        return NULL;
}

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(&init_net, se->se_callback_addr_val,
                                            se->se_callback_addr_len,
                                            (struct sockaddr *)&conn->cb_addr,
                                            sizeof(conn->cb_addr));

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

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

        conn->cb_prog = se->se_callback_prog;
        conn->cb_ident = se->se_callback_ident;
        memcpy(&conn->cb_saddr, &rqstp->rq_daddr, rqstp->rq_daddrlen);
        return;
out_err:
        conn->cb_addr.ss_family = AF_UNSPEC;
        conn->cb_addrlen = 0;
        dprintk(KERN_INFO "NFSD: this client (clientid %08x/%08x) "
                "will not receive delegations\n",
                clp->cl_clientid.cl_boot, clp->cl_clientid.cl_id);

        return;
}

/*
 * Cache a reply. nfsd4_check_drc_limit() has bounded the cache size.
 */
void
nfsd4_store_cache_entry(struct nfsd4_compoundres *resp)
{
        struct nfsd4_slot *slot = resp->cstate.slot;
        unsigned int base;

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

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

        slot->sl_flags |= NFSD4_SLOT_INITIALIZED;
        if (nfsd4_not_cached(resp)) {
                slot->sl_datalen = 0;
                return;
        }
        slot->sl_datalen = (char *)resp->p - (char *)resp->cstate.datap;
        base = (char *)resp->cstate.datap -
                                        (char *)resp->xbuf->head[0].iov_base;
        if (read_bytes_from_xdr_buf(resp->xbuf, base, slot->sl_data,
                                    slot->sl_datalen))
                WARN("%s: sessions DRC could not cache compound\n", __func__);
        return;
}

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

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

        /* Return nfserr_retry_uncached_rep in next operation. */
        if (args->opcnt > 1 && !(slot->sl_flags & NFSD4_SLOT_CACHETHIS)) {
                op = &args->ops[resp->opcnt++];
                op->status = nfserr_retry_uncached_rep;
                nfsd4_encode_operation(resp, op);
        }
        return op->status;
}

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

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

        /* Either returns 0 or nfserr_retry_uncached */
        status = nfsd4_enc_sequence_replay(resp->rqstp->rq_argp, resp);
        if (status == nfserr_retry_uncached_rep)
                return status;

        /* The sequence operation has been encoded, cstate->datap set. */
        memcpy(resp->cstate.datap, slot->sl_data, slot->sl_datalen);

        resp->opcnt = slot->sl_opcnt;
        resp->p = resp->cstate.datap + XDR_QUADLEN(slot->sl_datalen);
        status = slot->sl_status;

        return status;
}

/*
 * Set the exchange_id flags returned by the server.
 */
static void
nfsd4_set_ex_flags(struct nfs4_client *new, struct nfsd4_exchange_id *clid)
{
        /* pNFS is not supported */
        new->cl_exchange_flags |= EXCHGID4_FLAG_USE_NON_PNFS;

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

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

__be32
nfsd4_exchange_id(struct svc_rqst *rqstp,
                  struct nfsd4_compound_state *cstate,
                  struct nfsd4_exchange_id *exid)
{
        struct nfs4_client *unconf, *conf, *new;
        __be32 status;
        unsigned int            strhashval;
        char                    dname[HEXDIR_LEN];
        char                    addr_str[INET6_ADDRSTRLEN];
        nfs4_verifier           verf = exid->verifier;
        struct sockaddr         *sa = svc_addr(rqstp);

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

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

        /* Currently only support SP4_NONE */
        switch (exid->spa_how) {
        case SP4_NONE:
                break;
        case SP4_SSV:
                return nfserr_serverfault;
        default:
                BUG();                          /* checked by xdr code */
        case SP4_MACH_CRED:
                return nfserr_serverfault;      /* no excuse :-/ */
        }

        status = nfs4_make_rec_clidname(dname, &exid->clname);

        if (status)
                return status;

        strhashval = clientstr_hashval(dname);

        nfs4_lock_state();
        conf = find_confirmed_client_by_str(dname, strhashval);
        if (conf) {
                if (!clp_used_exchangeid(conf)) {
                        if (exid->flags & EXCHGID4_FLAG_UPD_CONFIRMED_REC_A) {
                                status = nfserr_inval; /* buggy client */
                                goto out;
                        }
                }
                if (!same_creds(&conf->cl_cred, &rqstp->rq_cred)) {
                        /* 18.35.4 case 9 */
                        if (exid->flags & EXCHGID4_FLAG_UPD_CONFIRMED_REC_A)
                                status = nfserr_perm;
                        else /* case 3 */
                                status = nfserr_clid_inuse;
                        goto out;
                }
                if (!same_verf(&verf, &conf->cl_verifier)) {
                        /* 18.35.4 case 8 */
                        if (exid->flags & EXCHGID4_FLAG_UPD_CONFIRMED_REC_A) {
                                status = nfserr_not_same;
                                goto out;
                        }
                        /* Client reboot: destroy old state */
                        expire_client(conf);
                        goto out_new;
                }
                if (!clp_used_exchangeid(conf)) {
                        status = nfserr_inval;
                        goto out;
                }
                /*
                 * Set bit when the owner id and verifier map to an already
                 * confirmed client id (18.35.3).
                 */
                exid->flags |= EXCHGID4_FLAG_CONFIRMED_R;

                /*
                 * Falling into 18.35.4 case 2, possible router replay.
                 * Leave confirmed record intact and return same result.
                 */
                new = conf;
                goto out_copy;
        }

        /* 18.35.4 case 7 */
        if (exid->flags & EXCHGID4_FLAG_UPD_CONFIRMED_REC_A) {
                status = nfserr_noent;
                goto out;
        }

        unconf  = find_unconfirmed_client_by_str(dname, strhashval);
        if (unconf) {
                /*
                 * Possible retry or client restart.  Per 18.35.4 case 4,
                 * a new unconfirmed record should be generated regardless
                 * of whether any properties have changed.
                 */
                expire_client(unconf);
        }

out_new:
        /* Normal case */
        new = create_client(exid->clname, dname, rqstp, &verf);
        if (new == NULL) {
                status = nfserr_jukebox;
                goto out;
        }

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

        exid->seqid = 1;
        nfsd4_set_ex_flags(new, exid);

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

out:
        nfs4_unlock_state();
        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 bool check_forechannel_attrs(struct nfsd4_channel_attrs fchannel)
{
        return fchannel.maxreq_sz < NFSD_MIN_REQ_HDR_SEQ_SZ
                || fchannel.maxresp_sz < NFSD_MIN_RESP_HDR_SEQ_SZ;
}

__be32
nfsd4_create_session(struct svc_rqst *rqstp,
                     struct nfsd4_compound_state *cstate,
                     struct nfsd4_create_session *cr_ses)
{
        struct sockaddr *sa = svc_addr(rqstp);
        struct nfs4_client *conf, *unconf;
        struct nfsd4_session *new;
        struct nfsd4_clid_slot *cs_slot = NULL;
        bool confirm_me = false;
        __be32 status = 0;

        if (cr_ses->flags & ~SESSION4_FLAG_MASK_A)
                return nfserr_inval;

        nfs4_lock_state();
        unconf = find_unconfirmed_client(&cr_ses->clientid);
        conf = find_confirmed_client(&cr_ses->clientid);

        if (conf) {
                cs_slot = &conf->cl_cs_slot;
                status = check_slot_seqid(cr_ses->seqid, cs_slot->sl_seqid, 0);
                if (status == nfserr_replay_cache) {
                        dprintk("Got a create_session replay! seqid= %d\n",
                                cs_slot->sl_seqid);
                        /* Return the cached reply status */
                        status = nfsd4_replay_create_session(cr_ses, cs_slot);
                        goto out;
                } else if (cr_ses->seqid != cs_slot->sl_seqid + 1) {
                        status = nfserr_seq_misordered;
                        dprintk("Sequence misordered!\n");
                        dprintk("Expected seqid= %d but got seqid= %d\n",
                                cs_slot->sl_seqid, cr_ses->seqid);
                        goto out;
                }
        } else if (unconf) {
                if (!same_creds(&unconf->cl_cred, &rqstp->rq_cred) ||
                    !rpc_cmp_addr(sa, (struct sockaddr *) &unconf->cl_addr)) {
                        status = nfserr_clid_inuse;
                        goto out;
                }

                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;
                }

                confirm_me = true;
                conf = unconf;
        } else {
                status = nfserr_stale_clientid;
                goto out;
        }

        /*
         * XXX: we should probably set this at creation time, and check
         * for consistent minorversion use throughout:
         */
        conf->cl_minorversion = 1;
        /*
         * We do not support RDMA or persistent sessions
         */
        cr_ses->flags &= ~SESSION4_PERSIST;
        cr_ses->flags &= ~SESSION4_RDMA;

        status = nfserr_toosmall;
        if (check_forechannel_attrs(cr_ses->fore_channel))
                goto out;

        status = nfserr_jukebox;
        new = alloc_init_session(rqstp, conf, cr_ses);
        if (!new)
                goto out;
        status = nfs_ok;
        memcpy(cr_ses->sessionid.data, new->se_sessionid.data,
               NFS4_MAX_SESSIONID_LEN);
        memcpy(&cr_ses->fore_channel, &new->se_fchannel,
                sizeof(struct nfsd4_channel_attrs));
        cs_slot->sl_seqid++;
        cr_ses->seqid = cs_slot->sl_seqid;

        /* cache solo and embedded create sessions under the state lock */
        nfsd4_cache_create_session(cr_ses, cs_slot, status);
        if (confirm_me)
                move_to_confirmed(conf);
out:
        nfs4_unlock_state();
        dprintk("%s returns %d\n", __func__, ntohl(status));
        return status;
}

static bool nfsd4_last_compound_op(struct svc_rqst *rqstp)
{
        struct nfsd4_compoundres *resp = rqstp->rq_resp;
        struct nfsd4_compoundargs *argp = rqstp->rq_argp;

        return argp->opcnt == resp->opcnt;
}

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_bind_conn_to_session(struct svc_rqst *rqstp,
                     struct nfsd4_compound_state *cstate,
                     struct nfsd4_bind_conn_to_session *bcts)
{
        __be32 status;

        if (!nfsd4_last_compound_op(rqstp))
                return nfserr_not_only_op;
        spin_lock(&client_lock);
        cstate->session = find_in_sessionid_hashtbl(&bcts->sessionid);
        /* Sorta weird: we only need the refcnt'ing because new_conn acquires
         * client_lock iself: */
        if (cstate->session) {
                nfsd4_get_session(cstate->session);
                atomic_inc(&cstate->session->se_client->cl_refcount);
        }
        spin_unlock(&client_lock);
        if (!cstate->session)
                return nfserr_badsession;

        status = nfsd4_map_bcts_dir(&bcts->dir);
        if (!status)
                nfsd4_new_conn(rqstp, cstate->session, bcts->dir);
        return status;
}

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

__be32
nfsd4_destroy_session(struct svc_rqst *r,
                      struct nfsd4_compound_state *cstate,
                      struct nfsd4_destroy_session *sessionid)
{
        struct nfsd4_session *ses;
        __be32 status = nfserr_badsession;

        /* Notes:
         * - The confirmed nfs4_client->cl_sessionid holds destroyed sessinid
         * - Should we return nfserr_back_chan_busy if waiting for
         *   callbacks on to-be-destroyed session?
         * - Do we need to clear any callback info from previous session?
         */

        if (nfsd4_compound_in_session(cstate->session, &sessionid->sessionid)) {
                if (!nfsd4_last_compound_op(r))
                        return nfserr_not_only_op;
        }
        dump_sessionid(__func__, &sessionid->sessionid);
        spin_lock(&client_lock);
        ses = find_in_sessionid_hashtbl(&sessionid->sessionid);
        if (!ses) {
                spin_unlock(&client_lock);
                goto out;
        }

        unhash_session(ses);
        spin_unlock(&client_lock);

        nfs4_lock_state();
        nfsd4_probe_callback_sync(ses->se_client);
        nfs4_unlock_state();

        spin_lock(&client_lock);
        nfsd4_del_conns(ses);
        nfsd4_put_session_locked(ses);
        spin_unlock(&client_lock);
        status = nfs_ok;
out:
        dprintk("%s returns %d\n", __func__, ntohl(status));
        return status;
}

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

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

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

        spin_lock(&clp->cl_lock);
        c = __nfsd4_find_conn(new->cn_xprt, ses);
        if (c) {
                spin_unlock(&clp->cl_lock);
                free_conn(new);
                return;
        }
        __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;
}

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

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

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

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

__be32
nfsd4_sequence(struct svc_rqst *rqstp,
               struct nfsd4_compound_state *cstate,
               struct nfsd4_sequence *seq)
{
        struct nfsd4_compoundres *resp = rqstp->rq_resp;
        struct nfsd4_session *session;
        struct nfsd4_slot *slot;
        struct nfsd4_conn *conn;
        __be32 status;

        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(&client_lock);
        status = nfserr_badsession;
        session = find_in_sessionid_hashtbl(&seq->sessionid);
        if (!session)
                goto out;

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

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

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

        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;
                cstate->slot = slot;
                cstate->session = session;
                /* 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;

        nfsd4_sequence_check_conn(conn, session);
        conn = NULL;

        /* 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;

out:
        /* Hold a session reference until done processing the compound. */
        if (cstate->session) {
                struct nfs4_client *clp = session->se_client;

                nfsd4_get_session(cstate->session);
                atomic_inc(&clp->cl_refcount);
                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;
                }
        }
        kfree(conn);
        spin_unlock(&client_lock);
        dprintk("%s: return %d\n", __func__, ntohl(status));
        return status;
}

static inline bool has_resources(struct nfs4_client *clp)
{
        return !list_empty(&clp->cl_openowners)
                || !list_empty(&clp->cl_delegations)
                || !list_empty(&clp->cl_sessions);
}

__be32
nfsd4_destroy_clientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, struct nfsd4_destroy_clientid *dc)
{
        struct nfs4_client *conf, *unconf, *clp;
        __be32 status = 0;

        nfs4_lock_state();
        unconf = find_unconfirmed_client(&dc->clientid);
        conf = find_confirmed_client(&dc->clientid);

        if (conf) {
                clp = conf;

                if (!is_client_expired(conf) && has_resources(conf)) {
                        status = nfserr_clientid_busy;
                        goto out;
                }

                /* rfc5661 18.50.3 */
                if (cstate->session && conf == cstate->session->se_client) {
                        status = nfserr_clientid_busy;
                        goto out;
                }
        } else if (unconf)
                clp = unconf;
        else {
                status = nfserr_stale_clientid;
                goto out;
        }

        expire_client(clp);
out:
        nfs4_unlock_state();
        dprintk("%s return %d\n", __func__, ntohl(status));
        return status;
}

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

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

        nfs4_lock_state();
        status = nfserr_complete_already;
        if (test_and_set_bit(NFSD4_CLIENT_RECLAIM_COMPLETE,
                             &cstate->session->se_client->cl_flags))
                goto out;

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

        status = nfs_ok;
        nfsd4_client_record_create(cstate->session->se_client);
out:
        nfs4_unlock_state();
        return status;
}

__be32
nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                  struct nfsd4_setclientid *setclid)
{
        struct xdr_netobj       clname = setclid->se_name;
        nfs4_verifier           clverifier = setclid->se_verf;
        unsigned int            strhashval;
        struct nfs4_client      *conf, *unconf, *new;
        __be32                  status;
        char                    dname[HEXDIR_LEN];
        
        status = nfs4_make_rec_clidname(dname, &clname);
        if (status)
                return status;

        /* 
         * XXX The Duplicate Request Cache (DRC) has been checked (??)
         * We get here on a DRC miss.
         */

        strhashval = clientstr_hashval(dname);

        nfs4_lock_state();
        conf = find_confirmed_client_by_str(dname, strhashval);
        if (conf) {
                /* RFC 3530 14.2.33 CASE 0: */
                status = nfserr_clid_inuse;
                if (clp_used_exchangeid(conf))
                        goto out;
                if (!same_creds(&conf->cl_cred, &rqstp->rq_cred)) {
                        char addr_str[INET6_ADDRSTRLEN];
                        rpc_ntop((struct sockaddr *) &conf->cl_addr, addr_str,
                                 sizeof(addr_str));
                        dprintk("NFSD: setclientid: string in use by client "
                                "at %s\n", addr_str);
                        goto out;
                }
        }
        /*
         * section 14.2.33 of RFC 3530 (under the heading "IMPLEMENTATION")
         * has a description of SETCLIENTID request processing consisting
         * of 5 bullet points, labeled as CASE0 - CASE4 below.
         */
        unconf = find_unconfirmed_client_by_str(dname, strhashval);
        status = nfserr_jukebox;
        if (!conf) {
                /*
                 * RFC 3530 14.2.33 CASE 4:
                 * placed first, because it is the normal case
                 */
                if (unconf)
                        expire_client(unconf);
                new = create_client(clname, dname, rqstp, &clverifier);
                if (new == NULL)
                        goto out;
                gen_clid(new);
        } else if (same_verf(&conf->cl_verifier, &clverifier)) {
                /*
                 * RFC 3530 14.2.33 CASE 1:
                 * probable callback update
                 */
                if (unconf) {
                        /* Note this is removing unconfirmed {*x***},
                         * which is stronger than RFC recommended {vxc**}.
                         * This has the advantage that there is at most
                         * one {*x***} in either list at any time.
                         */
                        expire_client(unconf);
                }
                new = create_client(clname, dname, rqstp, &clverifier);
                if (new == NULL)
                        goto out;
                copy_clid(new, conf);
        } else if (!unconf) {
                /*
                 * RFC 3530 14.2.33 CASE 2:
                 * probable client reboot; state will be removed if
                 * confirmed.
                 */
                new = create_client(clname, dname, rqstp, &clverifier);
                if (new == NULL)
                        goto out;
                gen_clid(new);
        } else {
                /*
                 * RFC 3530 14.2.33 CASE 3:
                 * probable client reboot; state will be removed if
                 * confirmed.
                 */
                expire_client(unconf);
                new = create_client(clname, dname, rqstp, &clverifier);
                if (new == NULL)
                        goto out;
                gen_clid(new);
        }
        /*
         * XXX: we should probably set this at creation time, and check
         * for consistent minorversion use throughout:
         */
        new->cl_minorversion = 0;
        gen_callback(new, setclid, rqstp);
        add_to_unconfirmed(new, strhashval);
        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));
        status = nfs_ok;
out:
        nfs4_unlock_state();
        return status;
}


/*
 * Section 14.2.34 of RFC 3530 (under the heading "IMPLEMENTATION") has
 * a description of SETCLIENTID_CONFIRM request processing consisting of 4
 * bullets, labeled as CASE1 - CASE4 below.
 */
__be32
nfsd4_setclientid_confirm(struct svc_rqst *rqstp,
                         struct nfsd4_compound_state *cstate,
                         struct nfsd4_setclientid_confirm *setclientid_confirm)
{
        struct nfs4_client *conf, *unconf;
        nfs4_verifier confirm = setclientid_confirm->sc_confirm; 
        clientid_t * clid = &setclientid_confirm->sc_clientid;
        __be32 status;

        if (STALE_CLIENTID(clid))
                return nfserr_stale_clientid;
        /* 
         * XXX The Duplicate Request Cache (DRC) has been checked (??)
         * We get here on a DRC miss.
         */

        nfs4_lock_state();

        conf = find_confirmed_client(clid);
        unconf = find_unconfirmed_client(clid);

        /*
         * section 14.2.34 of RFC 3530 has a description of
         * SETCLIENTID_CONFIRM request processing consisting
         * of 4 bullet points, labeled as CASE1 - CASE4 below.
         */
        status = nfserr_clid_inuse;
        if (conf && unconf && same_verf(&confirm, &unconf->cl_confirm)) {
                /*
                 * RFC 3530 14.2.34 CASE 1:
                 * callback update
                 */
                if (!same_creds(&conf->cl_cred, &unconf->cl_cred))
                        status = nfserr_clid_inuse;
                else {
                        nfsd4_change_callback(conf, &unconf->cl_cb_conn);
                        nfsd4_probe_callback(conf);
                        expire_client(unconf);
                        status = nfs_ok;
                }
        } else if (conf && !unconf) {
                /*
                 * RFC 3530 14.2.34 CASE 2:
                 * probable retransmitted request; play it safe and
                 * do nothing.
                 */
                if (!same_creds(&conf->cl_cred, &rqstp->rq_cred))
                        status = nfserr_clid_inuse;
                else
                        status = nfs_ok;
        } else if (!conf && unconf
                        && same_verf(&unconf->cl_confirm, &confirm)) {
                /*
                 * RFC 3530 14.2.34 CASE 3:
                 * Normal case; new or rebooted client:
                 */
                if (!same_creds(&unconf->cl_cred, &rqstp->rq_cred)) {
                        status = nfserr_clid_inuse;
                } else {
                        unsigned int hash =
                                clientstr_hashval(unconf->cl_recdir);
                        conf = find_confirmed_client_by_str(unconf->cl_recdir,
                                                            hash);
                        if (conf) {
                                nfsd4_client_record_remove(conf);
                                expire_client(conf);
                        }
                        move_to_confirmed(unconf);
                        conf = unconf;
                        nfsd4_probe_callback(conf);
                        status = nfs_ok;
                }
        } else if ((!conf || (conf && !same_verf(&conf->cl_confirm, &confirm)))
            && (!unconf || (unconf && !same_verf(&unconf->cl_confirm,
                                                                &confirm)))) {
                /*
                 * RFC 3530 14.2.34 CASE 4:
                 * Client probably hasn't noticed that we rebooted yet.
                 */
                status = nfserr_stale_clientid;
        }

        nfs4_unlock_state();
        return status;
}

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

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

        atomic_set(&fp->fi_ref, 1);
        INIT_LIST_HEAD(&fp->fi_hash);
        INIT_LIST_HEAD(&fp->fi_stateids);
        INIT_LIST_HEAD(&fp->fi_delegations);
        fp->fi_inode = igrab(ino);
        fp->fi_had_conflict = false;
        fp->fi_lease = NULL;
        memset(fp->fi_fds, 0, sizeof(fp->fi_fds));
        memset(fp->fi_access, 0, sizeof(fp->fi_access));
        spin_lock(&recall_lock);
        list_add(&fp->fi_hash, &file_hashtbl[hashval]);
        spin_unlock(&recall_lock);
}

static void
nfsd4_free_slab(struct kmem_cache **slab)
{
        if (*slab == NULL)
                return;
        kmem_cache_destroy(*slab);
        *slab = NULL;
}

void
nfsd4_free_slabs(void)
{
        nfsd4_free_slab(&openowner_slab);
        nfsd4_free_slab(&lockowner_slab);
        nfsd4_free_slab(&file_slab);
        nfsd4_free_slab(&stateid_slab);
        nfsd4_free_slab(&deleg_slab);
}

int
nfsd4_init_slabs(void)
{
        openowner_slab = kmem_cache_create("nfsd4_openowners",
                        sizeof(struct nfs4_openowner), 0, 0, NULL);
        if (openowner_slab == NULL)
                goto out_nomem;
        lockowner_slab = kmem_cache_create("nfsd4_lockowners",
                        sizeof(struct nfs4_openowner), 0, 0, NULL);
        if (lockowner_slab == NULL)
                goto out_nomem;
        file_slab = kmem_cache_create("nfsd4_files",
                        sizeof(struct nfs4_file), 0, 0, NULL);
        if (file_slab == NULL)
                goto out_nomem;
        stateid_slab = kmem_cache_create("nfsd4_stateids",
                        sizeof(struct nfs4_ol_stateid), 0, 0, NULL);
        if (stateid_slab == NULL)
                goto out_nomem;
        deleg_slab = kmem_cache_create("nfsd4_delegations",
                        sizeof(struct nfs4_delegation), 0, 0, NULL);
        if (deleg_slab == NULL)
                goto out_nomem;
        return 0;
out_nomem:
        nfsd4_free_slabs();
        dprintk("nfsd4: out of memory while initializing nfsv4\n");
        return -ENOMEM;
}

void nfs4_free_openowner(struct nfs4_openowner *oo)
{
        kfree(oo->oo_owner.so_owner.data);
        kmem_cache_free(openowner_slab, oo);
}

void nfs4_free_lockowner(struct nfs4_lockowner *lo)
{
        kfree(lo->lo_owner.so_owner.data);
        kmem_cache_free(lockowner_slab, lo);
}

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

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

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

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

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

static void hash_openowner(struct nfs4_openowner *oo, struct nfs4_client *clp, unsigned int strhashval)
{
        list_add(&oo->oo_owner.so_strhash, &ownerstr_hashtbl[strhashval]);
        list_add(&oo->oo_perclient, &clp->cl_openowners);
}

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

        oo = alloc_stateowner(openowner_slab, &open->op_owner, clp);
        if (!oo)
                return NULL;
        oo->oo_owner.so_is_open_owner = 1;
        oo->oo_owner.so_seqid = open->op_seqid;
        oo->oo_flags = NFS4_OO_NEW;
        oo->oo_time = 0;
        oo->oo_last_closed_stid = NULL;
        INIT_LIST_HEAD(&oo->oo_close_lru);
        hash_openowner(oo, clp, strhashval);
        return oo;
}

static void init_open_stateid(struct nfs4_ol_stateid *stp, struct nfs4_file *fp, struct nfsd4_open *open) {
        struct nfs4_openowner *oo = open->op_openowner;
        struct nfs4_client *clp = oo->oo_owner.so_client;

        init_stid(&stp->st_stid, clp, NFS4_OPEN_STID);
        INIT_LIST_HEAD(&stp->st_lockowners);
        list_add(&stp->st_perstateowner, &oo->oo_owner.so_stateids);
        list_add(&stp->st_perfile, &fp->fi_stateids);
        stp->st_stateowner = &oo->oo_owner;
        get_nfs4_file(fp);
        stp->st_file = fp;
        stp->st_access_bmap = 0;
        stp->st_deny_bmap = 0;
        set_access(open->op_share_access, stp);
        set_deny(open->op_share_deny, stp);
        stp->st_openstp = NULL;
}

static void
move_to_close_lru(struct nfs4_openowner *oo)
{
        dprintk("NFSD: move_to_close_lru nfs4_openowner %p\n", oo);

        list_move_tail(&oo->oo_close_lru, &close_lru);
        oo->oo_time = get_seconds();
}

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

static struct nfs4_openowner *
find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open)
{
        struct nfs4_stateowner *so;
        struct nfs4_openowner *oo;

        list_for_each_entry(so, &ownerstr_hashtbl[hashval], so_strhash) {
                if (!so->so_is_open_owner)
                        continue;
                if (same_owner_str(so, &open->op_owner, &open->op_clientid)) {
                        oo = openowner(so);
                        renew_client(oo->oo_owner.so_client);
                        return oo;
                }
        }
        return NULL;
}

/* search file_hashtbl[] for file */
static struct nfs4_file *
find_file(struct inode *ino)
{
        unsigned int hashval = file_hashval(ino);
        struct nfs4_file *fp;

        spin_lock(&recall_lock);
        list_for_each_entry(fp, &file_hashtbl[hashval], fi_hash) {
                if (fp->fi_inode == ino) {
                        get_nfs4_file(fp);
                        spin_unlock(&recall_lock);
                        return fp;
                }
        }
        spin_unlock(&recall_lock);
        return NULL;
}

/*
 * 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 inode *ino = current_fh->fh_dentry->d_inode;
        struct nfs4_file *fp;
        struct nfs4_ol_stateid *stp;
        __be32 ret;

        dprintk("NFSD: nfs4_share_conflict\n");

        fp = find_file(ino);
        if (!fp)
                return nfs_ok;
        ret = nfserr_locked;
        /* Search for conflicting share reservations */
        list_for_each_entry(stp, &fp->fi_stateids, st_perfile) {
                if (test_deny(deny_type, stp) ||
                    test_deny(NFS4_SHARE_DENY_BOTH, stp))
                        goto out;
        }
        ret = nfs_ok;
out:
        put_nfs4_file(fp);
        return ret;
}

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

        list_add_tail(&dp->dl_recall_lru, &del_recall_lru);

        /* only place dl_time is set. protected by lock_flocks*/
        dp->dl_time = get_seconds();

        nfsd4_cb_recall(dp);
}

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

        BUG_ON(!fp);
        /* We assume break_lease is only called once per lease: */
        BUG_ON(fp->fi_had_conflict);
        /*
         * 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(&recall_lock);
        fp->fi_had_conflict = true;
        list_for_each_entry(dp, &fp->fi_delegations, dl_perfile)
                nfsd_break_one_deleg(dp);
        spin_unlock(&recall_lock);
}

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

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

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

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

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

        strhashval = ownerstr_hashval(clientid->cl_id, &open->op_owner);
        oo = find_openstateowner_str(strhashval, open);
        open->op_openowner = oo;
        if (!oo) {
                clp = find_confirmed_client(clientid);
                if (clp == NULL)
                        return nfserr_expired;
                goto new_owner;
        }
        if (!(oo->oo_flags & NFS4_OO_CONFIRMED)) {
                /* Replace unconfirmed owners without checking for replay. */
                clp = oo->oo_owner.so_client;
                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;
        clp = oo->oo_owner.so_client;
        goto alloc_stateid;
new_owner:
        oo = alloc_init_open_stateowner(strhashval, clp, open);
        if (oo == NULL)
                return nfserr_jukebox;
        open->op_openowner = oo;
alloc_stateid:
        open->op_stp = nfs4_alloc_stateid(clp);
        if (!open->op_stp)
                return nfserr_jukebox;
        return nfs_ok;
}

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

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

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

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

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

static __be32
nfs4_check_deleg(struct nfs4_client *cl, struct nfs4_file *fp, struct nfsd4_open *open,
                struct nfs4_delegation **dp)
{
        int flags;
        __be32 status = nfserr_bad_stateid;

        *dp = find_deleg_stateid(cl, &open->op_delegate_stateid);
        if (*dp == NULL)
                goto out;
        flags = share_access_to_flags(open->op_share_access);
        status = nfs4_check_delegmode(*dp, flags);
        if (status)
                *dp = NULL;
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 __be32
nfs4_check_open(struct nfs4_file *fp, struct nfsd4_open *open, struct nfs4_ol_stateid **stpp)
{
        struct nfs4_ol_stateid *local;
        struct nfs4_openowner *oo = open->op_openowner;

        list_for_each_entry(local, &fp->fi_stateids, st_perfile) {
                /* ignore lock owners */
                if (local->st_stateowner->so_is_open_owner == 0)
                        continue;
                /* remember if we have seen this open owner */
                if (local->st_stateowner == &oo->oo_owner)
                        *stpp = local;
                /* check for conflicting share reservations */
                if (!test_share(local, open))
                        return nfserr_share_denied;
        }
        return nfs_ok;
}

static void nfs4_free_stateid(struct nfs4_ol_stateid *s)
{
        kmem_cache_free(stateid_slab, s);
}

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 __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
                struct svc_fh *cur_fh, struct nfsd4_open *open)
{
        __be32 status;
        int oflag = nfs4_access_to_omode(open->op_share_access);
        int access = nfs4_access_to_access(open->op_share_access);

        if (!fp->fi_fds[oflag]) {
                status = nfsd_open(rqstp, cur_fh, S_IFREG, access,
                        &fp->fi_fds[oflag]);
                if (status)
                        return status;
        }
        nfs4_file_get_access(fp, oflag);

        return nfs_ok;
}

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

static __be32
nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp, struct nfsd4_open *open)
{
        u32 op_share_access = open->op_share_access;
        bool new_access;
        __be32 status;

        new_access = !test_access(op_share_access, stp);
        if (new_access) {
                status = nfs4_get_vfs_file(rqstp, fp, cur_fh, open);
                if (status)
                        return status;
        }
        status = nfsd4_truncate(rqstp, cur_fh, open);
        if (status) {
                if (new_access) {
                        int oflag = nfs4_access_to_omode(op_share_access);
                        nfs4_file_put_access(fp, oflag);
                }
                return status;
        }
        /* remember the open */
        set_access(op_share_access, stp);
        set_deny(open->op_share_deny, stp);

        return nfs_ok;
}


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

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

static struct file_lock *nfs4_alloc_init_lease(struct nfs4_delegation *dp, int flag)
{
        struct file_lock *fl;

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

static int nfs4_setlease(struct nfs4_delegation *dp, int flag)
{
        struct nfs4_file *fp = dp->dl_file;
        struct file_lock *fl;
        int status;

        fl = nfs4_alloc_init_lease(dp, flag);
        if (!fl)
                return -ENOMEM;
        fl->fl_file = find_readable_file(fp);
        list_add(&dp->dl_perclnt, &dp->dl_stid.sc_client->cl_delegations);
        status = vfs_setlease(fl->fl_file, fl->fl_type, &fl);
        if (status) {
                list_del_init(&dp->dl_perclnt);
                locks_free_lock(fl);
                return -ENOMEM;
        }
        fp->fi_lease = fl;
        fp->fi_deleg_file = fl->fl_file;
        get_file(fp->fi_deleg_file);
        atomic_set(&fp->fi_delegees, 1);
        list_add(&dp->dl_perfile, &fp->fi_delegations);
        return 0;
}

static int nfs4_set_delegation(struct nfs4_delegation *dp, int flag)
{
        struct nfs4_file *fp = dp->dl_file;

        if (!fp->fi_lease)
                return nfs4_setlease(dp, flag);
        spin_lock(&recall_lock);
        if (fp->fi_had_conflict) {
                spin_unlock(&recall_lock);
                return -EAGAIN;
        }
        atomic_inc(&fp->fi_delegees);
        list_add(&dp->dl_perfile, &fp->fi_delegations);
        spin_unlock(&recall_lock);
        list_add(&dp->dl_perclnt, &dp->dl_stid.sc_client->cl_delegations);
        return 0;
}

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:
                        BUG();  /* not supposed to get here */
                }
        }
}

/*
 * Attempt to hand out a delegation.
 */
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 = container_of(stp->st_stateowner, struct nfs4_openowner, oo_owner);
        int cb_up;
        int status = 0, flag = 0;

        cb_up = nfsd4_cb_channel_good(oo->oo_owner.so_client);
        flag = NFS4_OPEN_DELEGATE_NONE;
        open->op_recall = 0;
        switch (open->op_claim_type) {
                case NFS4_OPEN_CLAIM_PREVIOUS:
                        if (!cb_up)
                                open->op_recall = 1;
                        flag = open->op_delegate_type;
                        if (flag == NFS4_OPEN_DELEGATE_NONE)
                                goto out;
                        break;
                case NFS4_OPEN_CLAIM_NULL:
                        /* Let's not give out any delegations till everyone's
                         * had the chance to reclaim theirs.... */
                        if (locks_in_grace())
                                goto out;
                        if (!cb_up || !(oo->oo_flags & NFS4_OO_CONFIRMED))
                                goto out;
                        if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE)
                                flag = NFS4_OPEN_DELEGATE_WRITE;
                        else
                                flag = NFS4_OPEN_DELEGATE_READ;
                        break;
                default:
                        goto out;
        }

        dp = alloc_init_deleg(oo->oo_owner.so_client, stp, fh, flag);
        if (dp == NULL)
                goto out_no_deleg;
        status = nfs4_set_delegation(dp, flag);
        if (status)
                goto out_free;

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

        dprintk("NFSD: delegation stateid=" STATEID_FMT "\n",
                STATEID_VAL(&dp->dl_stid.sc_stateid));
out:
        open->op_delegate_type = flag;
        if (flag == 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");

                /* 4.1 client asking for a delegation? */
                if (open->op_deleg_want)
                        nfsd4_open_deleg_none_ext(open, status);
        }
        return;
out_free:
        nfs4_put_delegation(dp);
out_no_deleg:
        flag = NFS4_OPEN_DELEGATE_NONE;
        goto out;
}

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.
         */
}

/*
 * called with nfs4_lock_state() held.
 */
__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 inode *ino = current_fh->fh_dentry->d_inode;
        struct nfs4_ol_stateid *stp = NULL;
        struct nfs4_delegation *dp = NULL;
        __be32 status;

        /*
         * Lookup file; if found, lookup stateid and check open request,
         * and check for delegations in the process of being recalled.
         * If not found, create the nfs4_file struct
         */
        fp = find_file(ino);
        if (fp) {
                if ((status = nfs4_check_open(fp, open, &stp)))
                        goto out;
                status = nfs4_check_deleg(cl, fp, open, &dp);
                if (status)
                        goto out;
        } else {
                status = nfserr_bad_stateid;
                if (nfsd4_is_deleg_cur(open))
                        goto out;
                status = nfserr_jukebox;
                fp = open->op_file;
                open->op_file = NULL;
                nfsd4_init_file(fp, ino);
        }

        /*
         * OPEN the file, or upgrade an existing OPEN.
         * If truncate fails, the OPEN fails.
         */
        if (stp) {
                /* Stateid was found, this is an OPEN upgrade */
                status = nfs4_upgrade_open(rqstp, fp, current_fh, stp, open);
                if (status)
                        goto out;
        } else {
                status = nfs4_get_vfs_file(rqstp, fp, current_fh, open);
                if (status)
                        goto out;
                stp = open->op_stp;
                open->op_stp = NULL;
                init_open_stateid(stp, fp, open);
                status = nfsd4_truncate(rqstp, current_fh, open);
                if (status) {
                        release_open_stateid(stp);
                        goto out;
                }
        }
        update_stateid(&stp->st_stid.sc_stateid);
        memcpy(&open->op_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));

        if (nfsd4_has_session(&resp->cstate)) {
                open->op_openowner->oo_flags |= NFS4_OO_CONFIRMED;

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

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

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

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

        return status;
}

void nfsd4_cleanup_open_state(struct nfsd4_open *open, __be32 status)
{
        if (open->op_openowner) {
                struct nfs4_openowner *oo = open->op_openowner;

                if (!list_empty(&oo->oo_owner.so_stateids))
                        list_del_init(&oo->oo_close_lru);
                if (oo->oo_flags & NFS4_OO_NEW) {
                        if (status) {
                                release_openowner(oo);
                                open->op_openowner = NULL;
                        } else
                                oo->oo_flags &= ~NFS4_OO_NEW;
                }
        }
        if (open->op_file)
                nfsd4_free_file(open->op_file);
        if (open->op_stp)
                nfs4_free_stateid(open->op_stp);
}

__be32
nfsd4_renew(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
            clientid_t *clid)
{
        struct nfs4_client *clp;
        __be32 status;

        nfs4_lock_state();
        dprintk("process_renew(%08x/%08x): starting\n", 
                        clid->cl_boot, clid->cl_id);
        status = nfserr_stale_clientid;
        if (STALE_CLIENTID(clid))
                goto out;
        clp = find_confirmed_client(clid);
        status = nfserr_expired;
        if (clp == NULL) {
                /* We assume the client took too long to RENEW. */
                dprintk("nfsd4_renew: clientid not found!\n");
                goto out;
        }
        status = nfserr_cb_path_down;
        if (!list_empty(&clp->cl_delegations)
                        && clp->cl_cb_state != NFSD4_CB_UP)
                goto out;
        status = nfs_ok;
out:
        nfs4_unlock_state();
        return status;
}

static struct lock_manager nfsd4_manager = {
};

static bool grace_ended;

static void
nfsd4_end_grace(void)
{
        /* do nothing if grace period already ended */
        if (grace_ended)
                return;

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

static time_t
nfs4_laundromat(void)
{
        struct nfs4_client *clp;
        struct nfs4_openowner *oo;
        struct nfs4_delegation *dp;
        struct list_head *pos, *next, reaplist;
        time_t cutoff = get_seconds() - nfsd4_lease;
        time_t t, clientid_val = nfsd4_lease;
        time_t u, test_val = nfsd4_lease;

        nfs4_lock_state();

        dprintk("NFSD: laundromat service - starting\n");
        nfsd4_end_grace();
        INIT_LIST_HEAD(&reaplist);
        spin_lock(&client_lock);
        list_for_each_safe(pos, next, &client_lru) {
                clp = list_entry(pos, struct nfs4_client, cl_lru);
                if (time_after((unsigned long)clp->cl_time, (unsigned long)cutoff)) {
                        t = clp->cl_time - cutoff;
                        if (clientid_val > t)
                                clientid_val = t;
                        break;
                }
                if (atomic_read(&clp->cl_refcount)) {
                        dprintk("NFSD: client in use (clientid %08x)\n",
                                clp->cl_clientid.cl_id);
                        continue;
                }
                unhash_client_locked(clp);
                list_add(&clp->cl_lru, &reaplist);
        }
        spin_unlock(&client_lock);
        list_for_each_safe(pos, next, &reaplist) {
                clp = list_entry(pos, struct nfs4_client, cl_lru);
                dprintk("NFSD: purging unused client (clientid %08x)\n",
                        clp->cl_clientid.cl_id);
                nfsd4_client_record_remove(clp);
                expire_client(clp);
        }
        spin_lock(&recall_lock);
        list_for_each_safe(pos, next, &del_recall_lru) {
                dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
                if (time_after((unsigned long)dp->dl_time, (unsigned long)cutoff)) {
                        u = dp->dl_time - cutoff;
                        if (test_val > u)
                                test_val = u;
                        break;
                }
                list_move(&dp->dl_recall_lru, &reaplist);
        }
        spin_unlock(&recall_lock);
        list_for_each_safe(pos, next, &reaplist) {
                dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
                unhash_delegation(dp);
        }
        test_val = nfsd4_lease;
        list_for_each_safe(pos, next, &close_lru) {
                oo = container_of(pos, struct nfs4_openowner, oo_close_lru);
                if (time_after((unsigned long)oo->oo_time, (unsigned long)cutoff)) {
                        u = oo->oo_time - cutoff;
                        if (test_val > u)
                                test_val = u;
                        break;
                }
                release_openowner(oo);
        }
        if (clientid_val < NFSD_LAUNDROMAT_MINTIMEOUT)
                clientid_val = NFSD_LAUNDROMAT_MINTIMEOUT;
        nfs4_unlock_state();
        return clientid_val;
}

static struct workqueue_struct *laundry_wq;
static void laundromat_main(struct work_struct *);
static DECLARE_DELAYED_WORK(laundromat_work, laundromat_main);

static void
laundromat_main(struct work_struct *not_used)
{
        time_t t;

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

static inline __be32 nfs4_check_fh(struct svc_fh *fhp, struct nfs4_ol_stateid *stp)
{
        if (fhp->fh_dentry->d_inode != stp->st_file->fi_inode)
                return nfserr_bad_stateid;
        return nfs_ok;
}

static int
STALE_STATEID(stateid_t *stateid)
{
        if (stateid->si_opaque.so_clid.cl_boot == boot_time)
                return 0;
        dprintk("NFSD: stale stateid " STATEID_FMT "!\n",
                STATEID_VAL(stateid));
        return 1;
}

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

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

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

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

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

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

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

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

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

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

__be32 nfs4_validate_stateid(struct nfs4_client *cl, stateid_t *stateid)
{
        struct nfs4_stid *s;
        struct nfs4_ol_stateid *ols;
        __be32 status;

        if (STALE_STATEID(stateid))
                return nfserr_stale_stateid;

        s = find_stateid(cl, stateid);
        if (!s)
                 return nfserr_stale_stateid;
        status = check_stateid_generation(stateid, &s->sc_stateid, 1);
        if (status)
                return status;
        if (!(s->sc_type & (NFS4_OPEN_STID | NFS4_LOCK_STID)))
                return nfs_ok;
        ols = openlockstateid(s);
        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_lookup_stateid(stateid_t *stateid, unsigned char typemask, struct nfs4_stid **s)
{
        struct nfs4_client *cl;

        if (ZERO_STATEID(stateid) || ONE_STATEID(stateid))
                return nfserr_bad_stateid;
        if (STALE_STATEID(stateid))
                return nfserr_stale_stateid;
        cl = find_confirmed_client(&stateid->si_opaque.so_clid);
        if (!cl)
                return nfserr_expired;
        *s = find_stateid_by_type(cl, stateid, typemask);
        if (!*s)
                return nfserr_bad_stateid;
        return nfs_ok;

}

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

        if (filpp)
                *filpp = NULL;

        if (grace_disallows_io(ino))
                return nfserr_grace;

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

        status = nfsd4_lookup_stateid(stateid, NFS4_DELEG_STID|NFS4_OPEN_STID|NFS4_LOCK_STID, &s);
        if (status)
                return status;
        status = check_stateid_generation(stateid, &s->sc_stateid, nfsd4_has_session(cstate));
        if (status)
                goto out;
        switch (s->sc_type) {
        case NFS4_DELEG_STID:
                dp = delegstateid(s);
                status = nfs4_check_delegmode(dp, flags);
                if (status)
                        goto out;
                if (filpp) {
                        *filpp = dp->dl_file->fi_deleg_file;
                        BUG_ON(!*filpp);
                }
                break;
        case NFS4_OPEN_STID:
        case NFS4_LOCK_STID:
                stp = openlockstateid(s);
                status = nfs4_check_fh(current_fh, stp);
                if (status)
                        goto out;
                if (stp->st_stateowner->so_is_open_owner
                    && !(openowner(stp->st_stateowner)->oo_flags & NFS4_OO_CONFIRMED))
                        goto out;
                status = nfs4_check_openmode(stp, flags);
                if (status)
                        goto out;
                if (filpp) {
                        if (flags & RD_STATE)
                                *filpp = find_readable_file(stp->st_file);
                        else
                                *filpp = find_writeable_file(stp->st_file);
                }
                break;
        default:
                return nfserr_bad_stateid;
        }
        status = nfs_ok;
out:
        return status;
}

static __be32
nfsd4_free_lock_stateid(struct nfs4_ol_stateid *stp)
{
        if (check_for_locks(stp->st_file, lockowner(stp->st_stateowner)))
                return nfserr_locks_held;
        release_lock_stateid(stp);
        return nfs_ok;
}

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

        nfs4_lock_state();
        list_for_each_entry(stateid, &test_stateid->ts_stateid_list, ts_id_list)
                stateid->ts_id_status = nfs4_validate_stateid(cl, &stateid->ts_id_stateid);
        nfs4_unlock_state();

        return nfs_ok;
}

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

        nfs4_lock_state();
        s = find_stateid(cl, stateid);
        if (!s)
                goto out;
        switch (s->sc_type) {
        case NFS4_DELEG_STID:
                ret = nfserr_locks_held;
                goto out;
        case NFS4_OPEN_STID:
        case NFS4_LOCK_STID:
                ret = check_stateid_generation(stateid, &s->sc_stateid, 1);
                if (ret)
                        goto out;
                if (s->sc_type == NFS4_LOCK_STID)
                        ret = nfsd4_free_lock_stateid(openlockstateid(s));
                else
                        ret = nfserr_locks_held;
                break;
        default:
                ret = nfserr_bad_stateid;
        }
out:
        nfs4_unlock_state();
        return ret;
}

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

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

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

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

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

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

        return nfs4_seqid_op_checks(cstate, stateid, seqid, *stpp);
}

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

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

__be32
nfsd4_open_confirm(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                   struct nfsd4_open_confirm *oc)
{
        __be32 status;
        struct nfs4_openowner *oo;
        struct nfs4_ol_stateid *stp;

        dprintk("NFSD: nfsd4_open_confirm on file %.*s\n",
                        (int)cstate->current_fh.fh_dentry->d_name.len,
                        cstate->current_fh.fh_dentry->d_name.name);

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

        nfs4_lock_state();

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

        nfsd4_client_record_create(oo->oo_owner.so_client);
        status = nfs_ok;
out:
        if (!cstate->replay_owner)
                nfs4_unlock_state();
        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_file, nfs4_access_to_omode(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:
                BUG();
        }
}

static void
reset_union_bmap_deny(unsigned long deny, struct nfs4_ol_stateid *stp)
{
        int i;
        for (i = 0; i < 4; i++) {
                if ((i & deny) != i)
                        clear_deny(i, stp);
        }
}

__be32
nfsd4_open_downgrade(struct svc_rqst *rqstp,
                     struct nfsd4_compound_state *cstate,
                     struct nfsd4_open_downgrade *od)
{
        __be32 status;
        struct nfs4_ol_stateid *stp;

        dprintk("NFSD: nfsd4_open_downgrade on file %.*s\n", 
                        (int)cstate->current_fh.fh_dentry->d_name.len,
                        cstate->current_fh.fh_dentry->d_name.name);

        /* 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);

        nfs4_lock_state();
        status = nfs4_preprocess_confirmed_seqid_op(cstate, od->od_seqid,
                                        &od->od_stateid, &stp);
        if (status)
                goto out; 
        status = nfserr_inval;
        if (!test_access(od->od_share_access, stp)) {
                dprintk("NFSD: access not a subset current bitmap: 0x%lx, input access=%08x\n",
                        stp->st_access_bmap, od->od_share_access);
                goto out;
        }
        if (!test_deny(od->od_share_deny, stp)) {
                dprintk("NFSD:deny not a subset current bitmap: 0x%lx, input deny=%08x\n",
                        stp->st_deny_bmap, od->od_share_deny);
                goto out;
        }
        nfs4_stateid_downgrade(stp, od->od_share_access);

        reset_union_bmap_deny(od->od_share_deny, stp);

        update_stateid(&stp->st_stid.sc_stateid);
        memcpy(&od->od_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));
        status = nfs_ok;
out:
        if (!cstate->replay_owner)
                nfs4_unlock_state();
        return status;
}

void nfsd4_purge_closed_stateid(struct nfs4_stateowner *so)
{
        struct nfs4_openowner *oo;
        struct nfs4_ol_stateid *s;

        if (!so->so_is_open_owner)
                return;
        oo = openowner(so);
        s = oo->oo_last_closed_stid;
        if (!s)
                return;
        if (!(oo->oo_flags & NFS4_OO_PURGE_CLOSE)) {
                /* Release the last_closed_stid on the next seqid bump: */
                oo->oo_flags |= NFS4_OO_PURGE_CLOSE;
                return;
        }
        oo->oo_flags &= ~NFS4_OO_PURGE_CLOSE;
        release_last_closed_stateid(oo);
}

static void nfsd4_close_open_stateid(struct nfs4_ol_stateid *s)
{
        unhash_open_stateid(s);
        s->st_stid.sc_type = NFS4_CLOSED_STID;
}

/*
 * nfs4_unlock_state() called after encode
 */
__be32
nfsd4_close(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
            struct nfsd4_close *close)
{
        __be32 status;
        struct nfs4_openowner *oo;
        struct nfs4_ol_stateid *stp;

        dprintk("NFSD: nfsd4_close on file %.*s\n", 
                        (int)cstate->current_fh.fh_dentry->d_name.len,
                        cstate->current_fh.fh_dentry->d_name.name);

        nfs4_lock_state();
        status = nfs4_preprocess_seqid_op(cstate, close->cl_seqid,
                                        &close->cl_stateid,
                                        NFS4_OPEN_STID|NFS4_CLOSED_STID,
                                        &stp);
        if (status)
                goto out; 
        oo = openowner(stp->st_stateowner);
        status = nfs_ok;
        update_stateid(&stp->st_stid.sc_stateid);
        memcpy(&close->cl_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));

        nfsd4_close_open_stateid(stp);
        oo->oo_last_closed_stid = stp;

        /* place unused nfs4_stateowners on so_close_lru list to be
         * released by the laundromat service after the lease period
         * to enable us to handle CLOSE replay
         */
        if (list_empty(&oo->oo_owner.so_stateids))
                move_to_close_lru(oo);
out:
        if (!cstate->replay_owner)
                nfs4_unlock_state();
        return status;
}

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

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

        nfs4_lock_state();
        status = nfsd4_lookup_stateid(stateid, NFS4_DELEG_STID, &s);
        if (status)
                goto out;
        dp = delegstateid(s);
        status = check_stateid_generation(stateid, &dp->dl_stid.sc_stateid, nfsd4_has_session(cstate));
        if (status)
                goto out;

        unhash_delegation(dp);
out:
        nfs4_unlock_state();

        return status;
}


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

#define LOCKOWNER_INO_HASH_BITS 8
#define LOCKOWNER_INO_HASH_SIZE (1 << LOCKOWNER_INO_HASH_BITS)
#define LOCKOWNER_INO_HASH_MASK (LOCKOWNER_INO_HASH_SIZE - 1)

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

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

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

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

static unsigned int lockowner_ino_hashval(struct inode *inode, u32 cl_id, struct xdr_netobj *ownername)
{
        return (file_hashval(inode) + cl_id
                        + opaque_hashval(ownername->data, ownername->len))
                & LOCKOWNER_INO_HASH_MASK;
}

static struct list_head lockowner_ino_hashtbl[LOCKOWNER_INO_HASH_SIZE];

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

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

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

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

static bool same_lockowner_ino(struct nfs4_lockowner *lo, struct inode *inode, clientid_t *clid, struct xdr_netobj *owner)
{
        struct nfs4_ol_stateid *lst;

        if (!same_owner_str(&lo->lo_owner, owner, clid))
                return false;
        lst = list_first_entry(&lo->lo_owner.so_stateids,
                               struct nfs4_ol_stateid, st_perstateowner);
        return lst->st_file->fi_inode == inode;
}

static struct nfs4_lockowner *
find_lockowner_str(struct inode *inode, clientid_t *clid,
                struct xdr_netobj *owner)
{
        unsigned int hashval = lockowner_ino_hashval(inode, clid->cl_id, owner);
        struct nfs4_lockowner *lo;

        list_for_each_entry(lo, &lockowner_ino_hashtbl[hashval], lo_owner_ino_hash) {
                if (same_lockowner_ino(lo, inode, clid, owner))
                        return lo;
        }
        return NULL;
}

static void hash_lockowner(struct nfs4_lockowner *lo, unsigned int strhashval, struct nfs4_client *clp, struct nfs4_ol_stateid *open_stp)
{
        struct inode *inode = open_stp->st_file->fi_inode;
        unsigned int inohash = lockowner_ino_hashval(inode,
                        clp->cl_clientid.cl_id, &lo->lo_owner.so_owner);

        list_add(&lo->lo_owner.so_strhash, &ownerstr_hashtbl[strhashval]);
        list_add(&lo->lo_owner_ino_hash, &lockowner_ino_hashtbl[inohash]);
        list_add(&lo->lo_perstateid, &open_stp->st_lockowners);
}

/*
 * 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;

        lo = alloc_stateowner(lockowner_slab, &lock->lk_new_owner, clp);
        if (!lo)
                return NULL;
        INIT_LIST_HEAD(&lo->lo_owner.so_stateids);
        lo->lo_owner.so_is_open_owner = 0;
        /* It is the openowner seqid that will be incremented in encode in the
         * case of new lockowners; so increment the lock seqid manually: */
        lo->lo_owner.so_seqid = lock->lk_new_lock_seqid + 1;
        hash_lockowner(lo, strhashval, clp, open_stp);
        return lo;
}

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

        stp = nfs4_alloc_stateid(clp);
        if (stp == NULL)
                return NULL;
        init_stid(&stp->st_stid, clp, NFS4_LOCK_STID);
        list_add(&stp->st_perfile, &fp->fi_stateids);
        list_add(&stp->st_perstateowner, &lo->lo_owner.so_stateids);
        stp->st_stateowner = &lo->lo_owner;
        get_nfs4_file(fp);
        stp->st_file = fp;
        stp->st_access_bmap = 0;
        stp->st_deny_bmap = open_stp->st_deny_bmap;
        stp->st_openstp = open_stp;
        return stp;
}

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

static void get_lock_access(struct nfs4_ol_stateid *lock_stp, u32 access)
{
        struct nfs4_file *fp = lock_stp->st_file;
        int oflag = nfs4_access_to_omode(access);

        if (test_access(access, lock_stp))
                return;
        nfs4_file_get_access(fp, oflag);
        set_access(access, lock_stp);
}

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

        lo = find_lockowner_str(fi->fi_inode, &cl->cl_clientid, &lock->v.new.owner);
        if (lo) {
                if (!cstate->minorversion)
                        return nfserr_bad_seqid;
                /* XXX: a lockowner always has exactly one stateid: */
                *lst = list_first_entry(&lo->lo_owner.so_stateids,
                                struct nfs4_ol_stateid, st_perstateowner);
                return nfs_ok;
        }
        strhashval = ownerstr_hashval(cl->cl_clientid.cl_id,
                        &lock->v.new.owner);
        lo = alloc_init_lock_stateowner(strhashval, cl, ost, lock);
        if (lo == NULL)
                return nfserr_jukebox;
        *lst = alloc_init_lock_stateid(lo, fi, ost);
        if (*lst == NULL) {
                release_lockowner(lo);
                return nfserr_jukebox;
        }
        *new = true;
        return nfs_ok;
}

/*
 *  LOCK operation 
 */
__be32
nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
           struct nfsd4_lock *lock)
{
        struct nfs4_openowner *open_sop = NULL;
        struct nfs4_lockowner *lock_sop = NULL;
        struct nfs4_ol_stateid *lock_stp;
        struct file *filp = NULL;
        struct file_lock file_lock;
        struct file_lock conflock;
        __be32 status = 0;
        bool new_state = false;
        int lkflg;
        int err;

        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;
        }

        nfs4_lock_state();

        if (lock->lk_is_new) {
                /*
                 * Client indicates that this is a new lockowner.
                 * Use open owner and open stateid to create lock owner and
                 * lock stateid.
                 */
                struct nfs4_ol_stateid *open_stp = NULL;

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

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

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

        locks_init_lock(&file_lock);
        switch (lock->lk_type) {
                case NFS4_READ_LT:
                case NFS4_READW_LT:
                        filp = find_readable_file(lock_stp->st_file);
                        if (filp)
                                get_lock_access(lock_stp, NFS4_SHARE_ACCESS_READ);
                        file_lock.fl_type = F_RDLCK;
                        break;
                case NFS4_WRITE_LT:
                case NFS4_WRITEW_LT:
                        filp = find_writeable_file(lock_stp->st_file);
                        if (filp)
                                get_lock_access(lock_stp, NFS4_SHARE_ACCESS_WRITE);
                        file_lock.fl_type = F_WRLCK;
                        break;
                default:
                        status = nfserr_inval;
                goto out;
        }
        if (!filp) {
                status = nfserr_openmode;
                goto out;
        }
        file_lock.fl_owner = (fl_owner_t)lock_sop;
        file_lock.fl_pid = current->tgid;
        file_lock.fl_file = filp;
        file_lock.fl_flags = FL_POSIX;
        file_lock.fl_lmops = &nfsd_posix_mng_ops;

        file_lock.fl_start = lock->lk_offset;
        file_lock.fl_end = last_byte_offset(lock->lk_offset, lock->lk_length);
        nfs4_transform_lock_offset(&file_lock);

        /*
        * Try to lock the file in the VFS.
        * Note: locks.c uses the BKL to protect the inode's lock list.
        */

        err = vfs_lock_file(filp, F_SETLK, &file_lock, &conflock);
        switch (-err) {
        case 0: /* success! */
                update_stateid(&lock_stp->st_stid.sc_stateid);
                memcpy(&lock->lk_resp_stateid, &lock_stp->st_stid.sc_stateid, 
                                sizeof(stateid_t));
                status = 0;
                break;
        case (EAGAIN):          /* conflock holds conflicting lock */
                status = nfserr_denied;
                dprintk("NFSD: nfsd4_lock: conflicting lock found!\n");
                nfs4_set_lock_denied(&conflock, &lock->lk_denied);
                break;
        case (EDEADLK):
                status = nfserr_deadlock;
                break;
        default:
                dprintk("NFSD: nfsd4_lock: vfs_lock_file() failed! status %d\n",err);
                status = nfserrno(err);
                break;
        }
out:
        if (status && new_state)
                release_lockowner(lock_sop);
        if (!cstate->replay_owner)
                nfs4_unlock_state();
        return status;
}

/*
 * The NFSv4 spec allows a client to do a LOCKT without holding an OPEN,
 * so we do a temporary open here just to get an open file to pass to
 * vfs_test_lock.  (Arguably perhaps test_lock should be done with an
 * inode operation.)
 */
static int nfsd_test_lock(struct svc_rqst *rqstp, struct svc_fh *fhp, struct file_lock *lock)
{
        struct file *file;
        int err;

        err = nfsd_open(rqstp, fhp, S_IFREG, NFSD_MAY_READ, &file);
        if (err)
                return err;
        err = vfs_test_lock(file, lock);
        nfsd_close(file);
        return err;
}

/*
 * LOCKT operation
 */
__be32
nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
            struct nfsd4_lockt *lockt)
{
        struct inode *inode;
        struct file_lock file_lock;
        struct nfs4_lockowner *lo;
        int error;
        __be32 status;

        if (locks_in_grace())
                return nfserr_grace;

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

        nfs4_lock_state();

        status = nfserr_stale_clientid;
        if (!nfsd4_has_session(cstate) && STALE_CLIENTID(&lockt->lt_clientid))
                goto out;

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

        inode = cstate->current_fh.fh_dentry->d_inode;
        locks_init_lock(&file_lock);
        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(inode, &lockt->lt_clientid, &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 = nfs_ok;
        error = nfsd_test_lock(rqstp, &cstate->current_fh, &file_lock);
        if (error) {
                status = nfserrno(error);
                goto out;
        }
        if (file_lock.fl_type != F_UNLCK) {
                status = nfserr_denied;
                nfs4_set_lock_denied(&file_lock, &lockt->lt_denied);
        }
out:
        nfs4_unlock_state();
        return status;
}

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

        nfs4_lock_state();
                                                                                
        status = nfs4_preprocess_seqid_op(cstate, locku->lu_seqid,
                                        &locku->lu_stateid, NFS4_LOCK_STID, &stp);
        if (status)
                goto out;
        filp = find_any_file(stp->st_file);
        if (!filp) {
                status = nfserr_lock_range;
                goto out;
        }
        BUG_ON(!filp);
        locks_init_lock(&file_lock);
        file_lock.fl_type = F_UNLCK;
        file_lock.fl_owner = (fl_owner_t)lockowner(stp->st_stateowner);
        file_lock.fl_pid = current->tgid;
        file_lock.fl_file = filp;
        file_lock.fl_flags = FL_POSIX; 
        file_lock.fl_lmops = &nfsd_posix_mng_ops;
        file_lock.fl_start = locku->lu_offset;

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

        /*
        *  Try to unlock the file in the VFS.
        */
        err = vfs_lock_file(filp, F_SETLK, &file_lock, NULL);
        if (err) {
                dprintk("NFSD: nfs4_locku: vfs_lock_file failed!\n");
                goto out_nfserr;
        }
        /*
        * OK, unlock succeeded; the only thing left to do is update the stateid.
        */
        update_stateid(&stp->st_stid.sc_stateid);
        memcpy(&locku->lu_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));

out:
        if (!cstate->replay_owner)
                nfs4_unlock_state();
        return status;

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

/*
 * returns
 *      1: locks held by lockowner
 *      0: no locks held by lockowner
 */
static int
check_for_locks(struct nfs4_file *filp, struct nfs4_lockowner *lowner)
{
        struct file_lock **flpp;
        struct inode *inode = filp->fi_inode;
        int status = 0;

        lock_flocks();
        for (flpp = &inode->i_flock; *flpp != NULL; flpp = &(*flpp)->fl_next) {
                if ((*flpp)->fl_owner == (fl_owner_t)lowner) {
                        status = 1;
                        goto out;
                }
        }
out:
        unlock_flocks();
        return status;
}

__be32
nfsd4_release_lockowner(struct svc_rqst *rqstp,
                        struct nfsd4_compound_state *cstate,
                        struct nfsd4_release_lockowner *rlockowner)
{
        clientid_t *clid = &rlockowner->rl_clientid;
        struct nfs4_stateowner *sop;
        struct nfs4_lockowner *lo;
        struct nfs4_ol_stateid *stp;
        struct xdr_netobj *owner = &rlockowner->rl_owner;
        struct list_head matches;
        unsigned int hashval = ownerstr_hashval(clid->cl_id, owner);
        __be32 status;

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

        /* XXX check for lease expiration */

        status = nfserr_stale_clientid;
        if (STALE_CLIENTID(clid))
                return status;

        nfs4_lock_state();

        status = nfserr_locks_held;
        INIT_LIST_HEAD(&matches);

        list_for_each_entry(sop, &ownerstr_hashtbl[hashval], so_strhash) {
                if (sop->so_is_open_owner)
                        continue;
                if (!same_owner_str(sop, owner, clid))
                        continue;
                list_for_each_entry(stp, &sop->so_stateids,
                                st_perstateowner) {
                        lo = lockowner(sop);
                        if (check_for_locks(stp->st_file, lo))
                                goto out;
                        list_add(&lo->lo_list, &matches);
                }
        }
        /* Clients probably won't expect us to return with some (but not all)
         * of the lockowner state released; so don't release any until all
         * have been checked. */
        status = nfs_ok;
        while (!list_empty(&matches)) {
                lo = list_entry(matches.next, struct nfs4_lockowner,
                                                                lo_list);
                /* unhash_stateowner deletes so_perclient only
                 * for openowners. */
                list_del(&lo->lo_list);
                release_lockowner(lo);
        }
out:
        nfs4_unlock_state();
        return status;
}

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

int
nfs4_has_reclaimed_state(const char *name, bool use_exchange_id)
{
        unsigned int strhashval = clientstr_hashval(name);
        struct nfs4_client *clp;

        clp = find_confirmed_client_by_str(name, strhashval);
        if (!clp)
                return 0;
        return test_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags);
}

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

        dprintk("NFSD nfs4_client_to_reclaim NAME: %.*s\n", HEXDIR_LEN, name);
        crp = alloc_reclaim();
        if (!crp)
                return 0;
        strhashval = clientstr_hashval(name);
        INIT_LIST_HEAD(&crp->cr_strhash);
        list_add(&crp->cr_strhash, &reclaim_str_hashtbl[strhashval]);
        memcpy(crp->cr_recdir, name, HEXDIR_LEN);
        reclaim_str_hashtbl_size++;
        return 1;
}

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

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

/*
 * called from OPEN, CLAIM_PREVIOUS with a new clientid. */
struct nfs4_client_reclaim *
nfsd4_find_reclaim_client(struct nfs4_client *clp)
{
        unsigned int strhashval;
        struct nfs4_client_reclaim *crp = NULL;

        dprintk("NFSD: nfs4_find_reclaim_client for %.*s with recdir %s\n",
                            clp->cl_name.len, clp->cl_name.data,
                            clp->cl_recdir);

        /* find clp->cl_name in reclaim_str_hashtbl */
        strhashval = clientstr_hashval(clp->cl_recdir);
        list_for_each_entry(crp, &reclaim_str_hashtbl[strhashval], cr_strhash) {
                if (same_name(crp->cr_recdir, clp->cl_recdir)) {
                        return crp;
                }
        }
        return NULL;
}

/*
* Called from OPEN. Look for clientid in reclaim list.
*/
__be32
nfs4_check_open_reclaim(clientid_t *clid)
{
        struct nfs4_client *clp;

        /* find clientid in conf_id_hashtbl */
        clp = find_confirmed_client(clid);
        if (clp == NULL)
                return nfserr_reclaim_bad;

        return nfsd4_client_record_check(clp) ? nfserr_reclaim_bad : nfs_ok;
}

#ifdef CONFIG_NFSD_FAULT_INJECTION

void nfsd_forget_clients(u64 num)
{
        struct nfs4_client *clp, *next;
        int count = 0;

        nfs4_lock_state();
        list_for_each_entry_safe(clp, next, &client_lru, cl_lru) {
                nfsd4_client_record_remove(clp);
                expire_client(clp);
                if (++count == num)
                        break;
        }
        nfs4_unlock_state();

        printk(KERN_INFO "NFSD: Forgot %d clients", count);
}

static void release_lockowner_sop(struct nfs4_stateowner *sop)
{
        release_lockowner(lockowner(sop));
}

static void release_openowner_sop(struct nfs4_stateowner *sop)
{
        release_openowner(openowner(sop));
}

static int nfsd_release_n_owners(u64 num, bool is_open_owner,
                                void (*release_sop)(struct nfs4_stateowner *))
{
        int i, count = 0;
        struct nfs4_stateowner *sop, *next;

        for (i = 0; i < OWNER_HASH_SIZE; i++) {
                list_for_each_entry_safe(sop, next, &ownerstr_hashtbl[i], so_strhash) {
                        if (sop->so_is_open_owner != is_open_owner)
                                continue;
                        release_sop(sop);
                        if (++count == num)
                                return count;
                }
        }
        return count;
}

void nfsd_forget_locks(u64 num)
{
        int count;

        nfs4_lock_state();
        count = nfsd_release_n_owners(num, false, release_lockowner_sop);
        nfs4_unlock_state();

        printk(KERN_INFO "NFSD: Forgot %d locks", count);
}

void nfsd_forget_openowners(u64 num)
{
        int count;

        nfs4_lock_state();
        count = nfsd_release_n_owners(num, true, release_openowner_sop);
        nfs4_unlock_state();

        printk(KERN_INFO "NFSD: Forgot %d open owners", count);
}

int nfsd_process_n_delegations(u64 num, void (*deleg_func)(struct nfs4_delegation *))
{
        int i, count = 0;
        struct nfs4_file *fp, *fnext;
        struct nfs4_delegation *dp, *dnext;

        for (i = 0; i < FILE_HASH_SIZE; i++) {
                list_for_each_entry_safe(fp, fnext, &file_hashtbl[i], fi_hash) {
                        list_for_each_entry_safe(dp, dnext, &fp->fi_delegations, dl_perfile) {
                                deleg_func(dp);
                                if (++count == num)
                                        return count;
                        }
                }
        }

        return count;
}

void nfsd_forget_delegations(u64 num)
{
        unsigned int count;

        nfs4_lock_state();
        count = nfsd_process_n_delegations(num, unhash_delegation);
        nfs4_unlock_state();

        printk(KERN_INFO "NFSD: Forgot %d delegations", count);
}

void nfsd_recall_delegations(u64 num)
{
        unsigned int count;

        nfs4_lock_state();
        spin_lock(&recall_lock);
        count = nfsd_process_n_delegations(num, nfsd_break_one_deleg);
        spin_unlock(&recall_lock);
        nfs4_unlock_state();

        printk(KERN_INFO "NFSD: Recalled %d delegations", count);
}

#endif /* CONFIG_NFSD_FAULT_INJECTION */

/* initialization to perform at module load time: */

void
nfs4_state_init(void)
{
        int i;

        for (i = 0; i < CLIENT_HASH_SIZE; i++) {
                INIT_LIST_HEAD(&conf_id_hashtbl[i]);
                INIT_LIST_HEAD(&conf_str_hashtbl[i]);
                INIT_LIST_HEAD(&unconf_str_hashtbl[i]);
                INIT_LIST_HEAD(&unconf_id_hashtbl[i]);
                INIT_LIST_HEAD(&reclaim_str_hashtbl[i]);
        }
        for (i = 0; i < SESSION_HASH_SIZE; i++)
                INIT_LIST_HEAD(&sessionid_hashtbl[i]);
        for (i = 0; i < FILE_HASH_SIZE; i++) {
                INIT_LIST_HEAD(&file_hashtbl[i]);
        }
        for (i = 0; i < OWNER_HASH_SIZE; i++) {
                INIT_LIST_HEAD(&ownerstr_hashtbl[i]);
        }
        for (i = 0; i < LOCKOWNER_INO_HASH_SIZE; i++)
                INIT_LIST_HEAD(&lockowner_ino_hashtbl[i]);
        INIT_LIST_HEAD(&close_lru);
        INIT_LIST_HEAD(&client_lru);
        INIT_LIST_HEAD(&del_recall_lru);
        reclaim_str_hashtbl_size = 0;
}

/*
 * 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);
}

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

int
nfs4_state_start(void)
{
        int ret;

        /*
         * FIXME: For now, we hang most of the pernet global stuff off of
         * init_net until nfsd is fully containerized. Eventually, we'll
         * need to pass a net pointer into this function, take a reference
         * to that instead and then do most of the rest of this on a per-net
         * basis.
         */
        get_net(&init_net);
        nfsd4_client_tracking_init(&init_net);
        boot_time = get_seconds();
        locks_start_grace(&nfsd4_manager);
        grace_ended = false;
        printk(KERN_INFO "NFSD: starting %ld-second grace period\n",
               nfsd4_grace);
        ret = set_callback_cred();
        if (ret) {
                ret = -ENOMEM;
                goto out_recovery;
        }
        laundry_wq = create_singlethread_workqueue("nfsd4");
        if (laundry_wq == NULL) {
                ret = -ENOMEM;
                goto out_recovery;
        }
        ret = nfsd4_create_callback_queue();
        if (ret)
                goto out_free_laundry;
        queue_delayed_work(laundry_wq, &laundromat_work, nfsd4_grace * HZ);
        set_max_delegations();
        return 0;
out_free_laundry:
        destroy_workqueue(laundry_wq);
out_recovery:
        nfsd4_client_tracking_exit(&init_net);
        put_net(&init_net);
        return ret;
}

static void
__nfs4_state_shutdown(void)
{
        int i;
        struct nfs4_client *clp = NULL;
        struct nfs4_delegation *dp = NULL;
        struct list_head *pos, *next, reaplist;

        for (i = 0; i < CLIENT_HASH_SIZE; i++) {
                while (!list_empty(&conf_id_hashtbl[i])) {
                        clp = list_entry(conf_id_hashtbl[i].next, struct nfs4_client, cl_idhash);
                        expire_client(clp);
                }
                while (!list_empty(&unconf_str_hashtbl[i])) {
                        clp = list_entry(unconf_str_hashtbl[i].next, struct nfs4_client, cl_strhash);
                        expire_client(clp);
                }
        }
        INIT_LIST_HEAD(&reaplist);
        spin_lock(&recall_lock);
        list_for_each_safe(pos, next, &del_recall_lru) {
                dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
                list_move(&dp->dl_recall_lru, &reaplist);
        }
        spin_unlock(&recall_lock);
        list_for_each_safe(pos, next, &reaplist) {
                dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
                unhash_delegation(dp);
        }

        nfsd4_client_tracking_exit(&init_net);
        put_net(&init_net);
}

void
nfs4_state_shutdown(void)
{
        cancel_delayed_work_sync(&laundromat_work);
        destroy_workqueue(laundry_wq);
        locks_end_grace(&nfsd4_manager);
        nfs4_lock_state();
        __nfs4_state_shutdown();
        nfs4_unlock_state();
        nfsd4_destroy_callback_queue();
}

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

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

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

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

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

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

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

/*
 * functions to consume current state id
 */

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

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

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

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

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

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

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

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