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

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

#include <linux/file.h>
#include <linux/smp_lock.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/swap.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/clnt.h>
#include "xdr4.h"
#include "vfs.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;
static u32 current_ownerid = 1;
static u32 current_fileid = 1;
static u32 current_delegid = 1;
static stateid_t zerostateid;             /* bits all 0 */
static stateid_t onestateid;              /* bits all 1 */
static u64 current_sessionid = 1;

#define ZERO_STATEID(stateid) (!memcmp((stateid), &zerostateid, sizeof(stateid_t)))
#define ONE_STATEID(stateid)  (!memcmp((stateid), &onestateid, sizeof(stateid_t)))

/* forward declarations */
static struct nfs4_stateid * find_stateid(stateid_t *stid, int flags);
static struct nfs4_delegation * find_delegation_stateid(struct inode *ino, stateid_t *stid);
static char user_recovery_dirname[PATH_MAX] = "/var/lib/nfs/v4recovery";
static void nfs4_set_recdir(char *recdir);

/* 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 *stateowner_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);
}

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 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);
                kmem_cache_free(file_slab, 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 nfs4_stateowner */
#define OWNER_HASH_BITS              8
#define OWNER_HASH_SIZE             (1 << OWNER_HASH_BITS)
#define OWNER_HASH_MASK             (OWNER_HASH_SIZE - 1)

#define ownerid_hashval(id) \
        ((id) & OWNER_HASH_MASK)
#define ownerstr_hashval(clientid, ownername) \
        (((clientid) + opaque_hashval((ownername.data), (ownername.len))) & OWNER_HASH_MASK)

static struct list_head ownerid_hashtbl[OWNER_HASH_SIZE];
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)
#define FILE_HASH_MASK                  (FILE_HASH_SIZE - 1)
/* hash table for (open)nfs4_stateid */
#define STATEID_HASH_BITS              10
#define STATEID_HASH_SIZE              (1 << STATEID_HASH_BITS)
#define STATEID_HASH_MASK              (STATEID_HASH_SIZE - 1)

#define file_hashval(x) \
        hash_ptr(x, FILE_HASH_BITS)
#define stateid_hashval(owner_id, file_id)  \
        (((owner_id) + (file_id)) & STATEID_HASH_MASK)

static struct list_head file_hashtbl[FILE_HASH_SIZE];
static struct list_head stateid_hashtbl[STATEID_HASH_SIZE];

static struct nfs4_delegation *
alloc_init_deleg(struct nfs4_client *clp, struct nfs4_stateid *stp, struct svc_fh *current_fh, u32 type)
{
        struct nfs4_delegation *dp;
        struct nfs4_file *fp = stp->st_file;
        struct nfs4_cb_conn *cb = &stp->st_stateowner->so_client->cl_cb_conn;

        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 = kmem_cache_alloc(deleg_slab, GFP_KERNEL);
        if (dp == NULL)
                return dp;
        num_delegations++;
        INIT_LIST_HEAD(&dp->dl_perfile);
        INIT_LIST_HEAD(&dp->dl_perclnt);
        INIT_LIST_HEAD(&dp->dl_recall_lru);
        dp->dl_client = clp;
        get_nfs4_file(fp);
        dp->dl_file = fp;
        dp->dl_flock = NULL;
        get_file(stp->st_vfs_file);
        dp->dl_vfs_file = stp->st_vfs_file;
        dp->dl_type = type;
        dp->dl_ident = cb->cb_ident;
        dp->dl_stateid.si_boot = boot_time;
        dp->dl_stateid.si_stateownerid = current_delegid++;
        dp->dl_stateid.si_fileid = 0;
        dp->dl_stateid.si_generation = 0;
        fh_copy_shallow(&dp->dl_fh, &current_fh->fh_handle);
        dp->dl_time = 0;
        atomic_set(&dp->dl_count, 1);
        list_add(&dp->dl_perfile, &fp->fi_delegations);
        list_add(&dp->dl_perclnt, &clp->cl_delegations);
        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--;
        }
}

/* Remove the associated file_lock first, then remove the delegation.
 * lease_modify() is called to remove the FS_LEASE file_lock from
 * the i_flock list, eventually calling nfsd's lock_manager
 * fl_release_callback.
 */
static void
nfs4_close_delegation(struct nfs4_delegation *dp)
{
        struct file *filp = dp->dl_vfs_file;

        dprintk("NFSD: close_delegation dp %p\n",dp);
        dp->dl_vfs_file = NULL;
        /* The following nfsd_close may not actually close the file,
         * but we want to remove the lease in any case. */
        if (dp->dl_flock)
                vfs_setlease(filp, F_UNLCK, &dp->dl_flock);
        nfsd_close(filp);
}

/* Called under the state lock. */
static void
unhash_delegation(struct nfs4_delegation *dp)
{
        list_del_init(&dp->dl_perfile);
        list_del_init(&dp->dl_perclnt);
        spin_lock(&recall_lock);
        list_del_init(&dp->dl_recall_lru);
        spin_unlock(&recall_lock);
        nfs4_close_delegation(dp);
        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)

#define clientid_hashval(id) \
        ((id) & CLIENT_HASH_MASK)
#define clientstr_hashval(name) \
        (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;

static void unhash_generic_stateid(struct nfs4_stateid *stp)
{
        list_del(&stp->st_hash);
        list_del(&stp->st_perfile);
        list_del(&stp->st_perstateowner);
}

static void free_generic_stateid(struct nfs4_stateid *stp)
{
        put_nfs4_file(stp->st_file);
        kmem_cache_free(stateid_slab, stp);
}

static void release_lock_stateid(struct nfs4_stateid *stp)
{
        unhash_generic_stateid(stp);
        locks_remove_posix(stp->st_vfs_file, (fl_owner_t)stp->st_stateowner);
        free_generic_stateid(stp);
}

static void unhash_lockowner(struct nfs4_stateowner *sop)
{
        struct nfs4_stateid *stp;

        list_del(&sop->so_idhash);
        list_del(&sop->so_strhash);
        list_del(&sop->so_perstateid);
        while (!list_empty(&sop->so_stateids)) {
                stp = list_first_entry(&sop->so_stateids,
                                struct nfs4_stateid, st_perstateowner);
                release_lock_stateid(stp);
        }
}

static void release_lockowner(struct nfs4_stateowner *sop)
{
        unhash_lockowner(sop);
        nfs4_put_stateowner(sop);
}

static void
release_stateid_lockowners(struct nfs4_stateid *open_stp)
{
        struct nfs4_stateowner *lock_sop;

        while (!list_empty(&open_stp->st_lockowners)) {
                lock_sop = list_entry(open_stp->st_lockowners.next,
                                struct nfs4_stateowner, so_perstateid);
                /* list_del(&open_stp->st_lockowners);  */
                BUG_ON(lock_sop->so_is_open_owner);
                release_lockowner(lock_sop);
        }
}

static void release_open_stateid(struct nfs4_stateid *stp)
{
        unhash_generic_stateid(stp);
        release_stateid_lockowners(stp);
        nfsd_close(stp->st_vfs_file);
        free_generic_stateid(stp);
}

static void unhash_openowner(struct nfs4_stateowner *sop)
{
        struct nfs4_stateid *stp;

        list_del(&sop->so_idhash);
        list_del(&sop->so_strhash);
        list_del(&sop->so_perclient);
        list_del(&sop->so_perstateid); /* XXX: necessary? */
        while (!list_empty(&sop->so_stateids)) {
                stp = list_first_entry(&sop->so_stateids,
                                struct nfs4_stateid, st_perstateowner);
                release_open_stateid(stp);
        }
}

static void release_openowner(struct nfs4_stateowner *sop)
{
        unhash_openowner(sop);
        list_del(&sop->so_close_lru);
        nfs4_put_stateowner(sop);
}

#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;
}

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]);
}

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)

/*
 * Give the client the number of ca_maxresponsesize_cached slots it
 * requests, of size bounded by NFSD_SLOT_CACHE_SIZE,
 * NFSD_MAX_MEM_PER_SESSION, and nfsd_drc_max_mem. Do not allow more
 * than NFSD_MAX_SLOTS_PER_SESSION.
 *
 * If we run out of reserved DRC memory we should (up to a point)
 * re-negotiate active sessions and reduce their slot usage to make
 * rooom for new connections. For now we just fail the create session.
 */
static int set_forechannel_drc_size(struct nfsd4_channel_attrs *fchan)
{
        int mem, size = fchan->maxresp_cached;

        if (fchan->maxreqs < 1)
                return nfserr_inval;

        if (size < NFSD_MIN_HDR_SEQ_SZ)
                size = NFSD_MIN_HDR_SEQ_SZ;
        size -= NFSD_MIN_HDR_SEQ_SZ;
        if (size > NFSD_SLOT_CACHE_SIZE)
                size = NFSD_SLOT_CACHE_SIZE;

        /* bound the maxreqs by NFSD_MAX_MEM_PER_SESSION */
        mem = fchan->maxreqs * size;
        if (mem > NFSD_MAX_MEM_PER_SESSION) {
                fchan->maxreqs = NFSD_MAX_MEM_PER_SESSION / size;
                if (fchan->maxreqs > NFSD_MAX_SLOTS_PER_SESSION)
                        fchan->maxreqs = NFSD_MAX_SLOTS_PER_SESSION;
                mem = fchan->maxreqs * size;
        }

        spin_lock(&nfsd_drc_lock);
        /* bound the total session drc memory ussage */
        if (mem + nfsd_drc_mem_used > nfsd_drc_max_mem) {
                fchan->maxreqs = (nfsd_drc_max_mem - nfsd_drc_mem_used) / size;
                mem = fchan->maxreqs * size;
        }
        nfsd_drc_mem_used += mem;
        spin_unlock(&nfsd_drc_lock);

        if (fchan->maxreqs == 0)
                return nfserr_jukebox;

        fchan->maxresp_cached = size + NFSD_MIN_HDR_SEQ_SZ;
        return 0;
}

/*
 * fchan holds the client values on input, and the server values on output
 * sv_max_mesg is the maximum payload plus one page for overhead.
 */
static int init_forechannel_attrs(struct svc_rqst *rqstp,
                                  struct nfsd4_channel_attrs *session_fchan,
                                  struct nfsd4_channel_attrs *fchan)
{
        int status = 0;
        __u32   maxcount = nfsd_serv->sv_max_mesg;

        /* headerpadsz set to zero in encode routine */

        /* Use the client's max request and max response size if possible */
        if (fchan->maxreq_sz > maxcount)
                fchan->maxreq_sz = maxcount;
        session_fchan->maxreq_sz = fchan->maxreq_sz;

        if (fchan->maxresp_sz > maxcount)
                fchan->maxresp_sz = maxcount;
        session_fchan->maxresp_sz = fchan->maxresp_sz;

        /* Use the client's maxops if possible */
        if (fchan->maxops > NFSD_MAX_OPS_PER_COMPOUND)
                fchan->maxops = NFSD_MAX_OPS_PER_COMPOUND;
        session_fchan->maxops = fchan->maxops;

        /* FIXME: Error means no more DRC pages so the server should
         * recover pages from existing sessions. For now fail session
         * creation.
         */
        status = set_forechannel_drc_size(fchan);

        session_fchan->maxresp_cached = fchan->maxresp_cached;
        session_fchan->maxreqs = fchan->maxreqs;

        dprintk("%s status %d\n", __func__, status);
        return status;
}

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
alloc_init_session(struct svc_rqst *rqstp, struct nfs4_client *clp,
                   struct nfsd4_create_session *cses)
{
        struct nfsd4_session *new, tmp;
        struct nfsd4_slot *sp;
        int idx, slotsize, cachesize, i;
        int status;

        memset(&tmp, 0, sizeof(tmp));

        /* FIXME: For now, we just accept the client back channel attributes. */
        tmp.se_bchannel = cses->back_channel;
        status = init_forechannel_attrs(rqstp, &tmp.se_fchannel,
                                        &cses->fore_channel);
        if (status)
                goto out;

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

        status = nfserr_jukebox;
        /* allocate struct nfsd4_session and slot table pointers in one piece */
        slotsize = tmp.se_fchannel.maxreqs * sizeof(struct nfsd4_slot *);
        new = kzalloc(sizeof(*new) + slotsize, GFP_KERNEL);
        if (!new)
                goto out;

        memcpy(new, &tmp, sizeof(*new));

        /* allocate each struct nfsd4_slot and data cache in one piece */
        cachesize = slot_bytes(&new->se_fchannel);
        for (i = 0; i < new->se_fchannel.maxreqs; i++) {
                sp = kzalloc(sizeof(*sp) + cachesize, GFP_KERNEL);
                if (!sp)
                        goto out_free;
                new->se_slots[i] = sp;
        }

        new->se_client = clp;
        gen_sessionid(new);
        idx = hash_sessionid(&new->se_sessionid);
        memcpy(clp->cl_sessionid.data, new->se_sessionid.data,
               NFS4_MAX_SESSIONID_LEN);

        new->se_flags = cses->flags;
        kref_init(&new->se_ref);
        spin_lock(&client_lock);
        list_add(&new->se_hash, &sessionid_hashtbl[idx]);
        list_add(&new->se_perclnt, &clp->cl_sessions);
        spin_unlock(&client_lock);

        status = nfs_ok;
out:
        return status;
out_free:
        free_session_slots(new);
        kfree(new);
        goto out;
}

/* 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);
        list_del(&ses->se_perclnt);
}

void
free_session(struct kref *kref)
{
        struct nfsd4_session *ses;
        int mem;

        ses = container_of(kref, struct nfsd4_session, se_ref);
        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);
}

/* 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;
        }

        /*
        * Move client to the end to the LRU list.
        */
        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 = kmalloc(name.len, GFP_KERNEL);
        if (clp->cl_name.data == NULL) {
                kfree(clp);
                return NULL;
        }
        memcpy(clp->cl_name.data, name.data, name.len);
        clp->cl_name.len = name.len;
        return clp;
}

static inline void
free_client(struct nfs4_client *clp)
{
        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)
{
        mark_client_expired(clp);
        list_del(&clp->cl_lru);
        while (!list_empty(&clp->cl_sessions)) {
                struct nfsd4_session  *ses;
                ses = list_entry(clp->cl_sessions.next, struct nfsd4_session,
                                 se_perclnt);
                unhash_session(ses);
                nfsd4_put_session(ses);
        }
}

static void
expire_client(struct nfs4_client *clp)
{
        struct nfs4_stateowner *sop;
        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);
                dprintk("NFSD: expire client. dp %p, fp %p\n", dp,
                                dp->dl_flock);
                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);
                list_del_init(&dp->dl_recall_lru);
                unhash_delegation(dp);
        }
        while (!list_empty(&clp->cl_openowners)) {
                sop = list_entry(clp->cl_openowners.next, struct nfs4_stateowner, so_perclient);
                release_openowner(sop);
        }
        nfsd4_set_callback_client(clp, NULL);
        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)
{
        static u32 i;
        u32 *p;

        p = (u32 *)clp->cl_confirm.data;
        *p++ = get_seconds();
        *p++ = i++;
}

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;

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

        memcpy(clp->cl_recdir, recdir, HEXDIR_LEN);
        atomic_set(&clp->cl_refcount, 0);
        atomic_set(&clp->cl_cb_set, 0);
        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_sessions);
        INIT_LIST_HEAD(&clp->cl_lru);
        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);

        return clp;
}

static int check_name(struct xdr_netobj name)
{
        if (name.len == 0) 
                return 0;
        if (name.len > NFS4_OPAQUE_LIMIT) {
                dprintk("NFSD: check_name: name too long(%d)!\n", name.len);
                return 0;
        }
        return 1;
}

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))
                        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;
}

/*
 * Return 1 iff clp's clientid establishment method matches the use_exchange_id
 * parameter. Matching is based on the fact the at least one of the
 * EXCHGID4_FLAG_USE_{NON_PNFS,PNFS_MDS,PNFS_DS} flags must be set for v4.1
 *
 * FIXME: we need to unify the clientid namespaces for nfsv4.x
 * and correctly deal with client upgrade/downgrade in EXCHANGE_ID
 * and SET_CLIENTID{,_CONFIRM}
 */
static inline int
match_clientid_establishment(struct nfs4_client *clp, bool use_exchange_id)
{
        bool has_exchange_flags = (clp->cl_exchange_flags != 0);
        return use_exchange_id == has_exchange_flags;
}

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

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

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

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

static void
gen_callback(struct nfs4_client *clp, struct nfsd4_setclientid *se, u32 scopeid)
{
        struct nfs4_cb_conn *cb = &clp->cl_cb_conn;
        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;

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

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

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

        cb->cb_minorversion = 0;
        cb->cb_prog = se->se_callback_prog;
        cb->cb_ident = se->se_callback_ident;
        return;
out_err:
        cb->cb_addr.ss_family = AF_UNSPEC;
        cb->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;

        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;

        dprintk("--> %s resp->opcnt %d cachethis %u \n", __func__,
                resp->opcnt, resp->cstate.slot->sl_cachethis);

        /* 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_cachethis == 0) {
                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;
        int 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 (!check_name(exid->clname) || (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_encr_alg_unsupp;
        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)
                goto error;

        strhashval = clientstr_hashval(dname);

        nfs4_lock_state();
        status = nfs_ok;

        conf = find_confirmed_client_by_str(dname, strhashval, true);
        if (conf) {
                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 (!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;
                                goto out;
                        }
                        expire_client(conf);
                        goto out_new;
                }
                /*
                 * 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.
                 */
                copy_verf(conf, &verf);
                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, true);
        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();
error:
        dprintk("nfsd4_exchange_id returns %d\n", ntohl(status));
        return status;
}

static int
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;
        }
        /* Normal */
        if (likely(seqid == slot_seqid + 1))
                return nfs_ok;
        /* Replay */
        if (seqid == slot_seqid)
                return nfserr_replay_cache;
        /* Wraparound */
        if (seqid == 1 && (slot_seqid + 1) == 0)
                return nfs_ok;
        /* Misordered replay or misordered new request */
        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, int 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;
}

__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_clid_slot *cs_slot = NULL;
        int status = 0;

        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;
                }
                cs_slot->sl_seqid++;
        } 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_cache;
                }

                cs_slot->sl_seqid++; /* from 0 to 1 */
                move_to_confirmed(unconf);

                if (cr_ses->flags & SESSION4_BACK_CHAN) {
                        unconf->cl_cb_conn.cb_xprt = rqstp->rq_xprt;
                        svc_xprt_get(rqstp->rq_xprt);
                        rpc_copy_addr(
                                (struct sockaddr *)&unconf->cl_cb_conn.cb_addr,
                                sa);
                        unconf->cl_cb_conn.cb_addrlen = svc_addr_len(sa);
                        unconf->cl_cb_conn.cb_minorversion =
                                cstate->minorversion;
                        unconf->cl_cb_conn.cb_prog = cr_ses->callback_prog;
                        unconf->cl_cb_seq_nr = 1;
                        nfsd4_probe_callback(unconf, &unconf->cl_cb_conn);
                }
                conf = unconf;
        } else {
                status = nfserr_stale_clientid;
                goto out;
        }

        /*
         * We do not support RDMA or persistent sessions
         */
        cr_ses->flags &= ~SESSION4_PERSIST;
        cr_ses->flags &= ~SESSION4_RDMA;

        status = alloc_init_session(rqstp, conf, cr_ses);
        if (status)
                goto out;

        memcpy(cr_ses->sessionid.data, conf->cl_sessionid.data,
               NFS4_MAX_SESSIONID_LEN);
        cr_ses->seqid = cs_slot->sl_seqid;

out_cache:
        /* cache solo and embedded create sessions under the state lock */
        nfsd4_cache_create_session(cr_ses, cs_slot, status);
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 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;
        u32 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();
        /* wait for callbacks */
        nfsd4_set_callback_client(ses->se_client, NULL);
        nfs4_unlock_state();
        nfsd4_put_session(ses);
        status = nfs_ok;
out:
        dprintk("%s returns %d\n", __func__, ntohl(status));
        return status;
}

__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;
        int status;

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

        spin_lock(&client_lock);
        status = nfserr_badsession;
        session = find_in_sessionid_hashtbl(&seq->sessionid);
        if (!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_inuse);
        if (status == nfserr_replay_cache) {
                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;

        /* Success! bump slot seqid */
        slot->sl_inuse = true;
        slot->sl_seqid = seq->seqid;
        slot->sl_cachethis = seq->cachethis;

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

out:
        /* Hold a session reference until done processing the compound. */
        if (cstate->session) {
                nfsd4_get_session(cstate->session);
                atomic_inc(&session->se_client->cl_refcount);
        }
        spin_unlock(&client_lock);
        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)
{
        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();
        if (is_client_expired(cstate->session->se_client)) {
                nfs4_unlock_state();
                /*
                 * 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.
                 */
                return nfserr_stale_clientid;
        }
        nfsd4_create_clid_dir(cstate->session->se_client);
        nfs4_unlock_state();
        return nfs_ok;
}

__be32
nfsd4_setclientid(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                  struct nfsd4_setclientid *setclid)
{
        struct sockaddr         *sa = svc_addr(rqstp);
        struct xdr_netobj       clname = { 
                .len = setclid->se_namelen,
                .data = setclid->se_name,
        };
        nfs4_verifier           clverifier = setclid->se_verf;
        unsigned int            strhashval;
        struct nfs4_client      *conf, *unconf, *new;
        __be32                  status;
        char                    dname[HEXDIR_LEN];
        
        if (!check_name(clname))
                return nfserr_inval;

        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, false);
        if (conf) {
                /* RFC 3530 14.2.33 CASE 0: */
                status = nfserr_clid_inuse;
                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, false);
        status = nfserr_resource;
        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);
        }
        gen_callback(new, setclid, rpc_get_scope_id(sa));
        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 sockaddr *sa = svc_addr(rqstp);
        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);

        status = nfserr_clid_inuse;
        if (conf && !rpc_cmp_addr((struct sockaddr *) &conf->cl_addr, sa))
                goto out;
        if (unconf && !rpc_cmp_addr((struct sockaddr *) &unconf->cl_addr, sa))
                goto out;

        /*
         * 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.
         */
        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 {
                        atomic_set(&conf->cl_cb_set, 0);
                        nfsd4_probe_callback(conf, &unconf->cl_cb_conn);
                        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, false);
                        if (conf) {
                                nfsd4_remove_clid_dir(conf);
                                expire_client(conf);
                        }
                        move_to_confirmed(unconf);
                        conf = unconf;
                        nfsd4_probe_callback(conf, &conf->cl_cb_conn);
                        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;
        } else {
                /* check that we have hit one of the cases...*/
                status = nfserr_clid_inuse;
        }
out:
        nfs4_unlock_state();
        return status;
}

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

        fp = kmem_cache_alloc(file_slab, GFP_KERNEL);
        if (fp) {
                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_id = current_fileid++;
                fp->fi_had_conflict = false;
                spin_lock(&recall_lock);
                list_add(&fp->fi_hash, &file_hashtbl[hashval]);
                spin_unlock(&recall_lock);
                return fp;
        }
        return NULL;
}

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(&stateowner_slab);
        nfsd4_free_slab(&file_slab);
        nfsd4_free_slab(&stateid_slab);
        nfsd4_free_slab(&deleg_slab);
}

static int
nfsd4_init_slabs(void)
{
        stateowner_slab = kmem_cache_create("nfsd4_stateowners",
                        sizeof(struct nfs4_stateowner), 0, 0, NULL);
        if (stateowner_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_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_stateowner(struct kref *kref)
{
        struct nfs4_stateowner *sop =
                container_of(kref, struct nfs4_stateowner, so_ref);
        kfree(sop->so_owner.data);
        kmem_cache_free(stateowner_slab, sop);
}

static inline struct nfs4_stateowner *
alloc_stateowner(struct xdr_netobj *owner)
{
        struct nfs4_stateowner *sop;

        if ((sop = kmem_cache_alloc(stateowner_slab, GFP_KERNEL))) {
                if ((sop->so_owner.data = kmalloc(owner->len, GFP_KERNEL))) {
                        memcpy(sop->so_owner.data, owner->data, owner->len);
                        sop->so_owner.len = owner->len;
                        kref_init(&sop->so_ref);
                        return sop;
                } 
                kmem_cache_free(stateowner_slab, sop);
        }
        return NULL;
}

static struct nfs4_stateowner *
alloc_init_open_stateowner(unsigned int strhashval, struct nfs4_client *clp, struct nfsd4_open *open) {
        struct nfs4_stateowner *sop;
        struct nfs4_replay *rp;
        unsigned int idhashval;

        if (!(sop = alloc_stateowner(&open->op_owner)))
                return NULL;
        idhashval = ownerid_hashval(current_ownerid);
        INIT_LIST_HEAD(&sop->so_idhash);
        INIT_LIST_HEAD(&sop->so_strhash);
        INIT_LIST_HEAD(&sop->so_perclient);
        INIT_LIST_HEAD(&sop->so_stateids);
        INIT_LIST_HEAD(&sop->so_perstateid);  /* not used */
        INIT_LIST_HEAD(&sop->so_close_lru);
        sop->so_time = 0;
        list_add(&sop->so_idhash, &ownerid_hashtbl[idhashval]);
        list_add(&sop->so_strhash, &ownerstr_hashtbl[strhashval]);
        list_add(&sop->so_perclient, &clp->cl_openowners);
        sop->so_is_open_owner = 1;
        sop->so_id = current_ownerid++;
        sop->so_client = clp;
        sop->so_seqid = open->op_seqid;
        sop->so_confirmed = 0;
        rp = &sop->so_replay;
        rp->rp_status = nfserr_serverfault;
        rp->rp_buflen = 0;
        rp->rp_buf = rp->rp_ibuf;
        return sop;
}

static inline void
init_stateid(struct nfs4_stateid *stp, struct nfs4_file *fp, struct nfsd4_open *open) {
        struct nfs4_stateowner *sop = open->op_stateowner;
        unsigned int hashval = stateid_hashval(sop->so_id, fp->fi_id);

        INIT_LIST_HEAD(&stp->st_hash);
        INIT_LIST_HEAD(&stp->st_perstateowner);
        INIT_LIST_HEAD(&stp->st_lockowners);
        INIT_LIST_HEAD(&stp->st_perfile);
        list_add(&stp->st_hash, &stateid_hashtbl[hashval]);
        list_add(&stp->st_perstateowner, &sop->so_stateids);
        list_add(&stp->st_perfile, &fp->fi_stateids);
        stp->st_stateowner = sop;
        get_nfs4_file(fp);
        stp->st_file = fp;
        stp->st_stateid.si_boot = boot_time;
        stp->st_stateid.si_stateownerid = sop->so_id;
        stp->st_stateid.si_fileid = fp->fi_id;
        stp->st_stateid.si_generation = 0;
        stp->st_access_bmap = 0;
        stp->st_deny_bmap = 0;
        __set_bit(open->op_share_access & ~NFS4_SHARE_WANT_MASK,
                  &stp->st_access_bmap);
        __set_bit(open->op_share_deny, &stp->st_deny_bmap);
        stp->st_openstp = NULL;
}

static void
move_to_close_lru(struct nfs4_stateowner *sop)
{
        dprintk("NFSD: move_to_close_lru nfs4_stateowner %p\n", sop);

        list_move_tail(&sop->so_close_lru, &close_lru);
        sop->so_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_stateowner *
find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open)
{
        struct nfs4_stateowner *so = NULL;

        list_for_each_entry(so, &ownerstr_hashtbl[hashval], so_strhash) {
                if (same_owner_str(so, &open->op_owner, &open->op_clientid))
                        return so;
        }
        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;
}

static inline int access_valid(u32 x, u32 minorversion)
{
        if ((x & NFS4_SHARE_ACCESS_MASK) < NFS4_SHARE_ACCESS_READ)
                return 0;
        if ((x & NFS4_SHARE_ACCESS_MASK) > NFS4_SHARE_ACCESS_BOTH)
                return 0;
        x &= ~NFS4_SHARE_ACCESS_MASK;
        if (minorversion && x) {
                if ((x & NFS4_SHARE_WANT_MASK) > NFS4_SHARE_WANT_CANCEL)
                        return 0;
                if ((x & NFS4_SHARE_WHEN_MASK) > NFS4_SHARE_PUSH_DELEG_WHEN_UNCONTENDED)
                        return 0;
                x &= ~(NFS4_SHARE_WANT_MASK | NFS4_SHARE_WHEN_MASK);
        }
        if (x)
                return 0;
        return 1;
}

static inline int deny_valid(u32 x)
{
        /* Note: unlike access bits, deny bits may be zero. */
        return x <= NFS4_SHARE_DENY_BOTH;
}

/*
 * 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 void
set_access(unsigned int *access, unsigned long bmap) {
        int i;

        *access = 0;
        for (i = 1; i < 4; i++) {
                if (test_bit(i, &bmap))
                        *access |= i;
        }
}

static void
set_deny(unsigned int *deny, unsigned long bmap) {
        int i;

        *deny = 0;
        for (i = 0; i < 4; i++) {
                if (test_bit(i, &bmap))
                        *deny |= i ;
        }
}

static int
test_share(struct nfs4_stateid *stp, struct nfsd4_open *open) {
        unsigned int access, deny;

        set_access(&access, stp->st_access_bmap);
        set_deny(&deny, stp->st_deny_bmap);
        if ((access & open->op_share_deny) || (deny & open->op_share_access))
                return 0;
        return 1;
}

/*
 * 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_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_bit(deny_type, &stp->st_deny_bmap) ||
                    test_bit(NFS4_SHARE_DENY_BOTH, &stp->st_deny_bmap))
                        goto out;
        }
        ret = nfs_ok;
out:
        put_nfs4_file(fp);
        return ret;
}

static inline void
nfs4_file_downgrade(struct file *filp, unsigned int share_access)
{
        if (share_access & NFS4_SHARE_ACCESS_WRITE) {
                drop_file_write_access(filp);
                spin_lock(&filp->f_lock);
                filp->f_mode = (filp->f_mode | FMODE_READ) & ~FMODE_WRITE;
                spin_unlock(&filp->f_lock);
        }
}

/*
 * Spawn a thread to perform a recall on the delegation represented
 * by the lease (file_lock)
 *
 * Called from break_lease() with lock_kernel() held.
 * Note: we assume break_lease will only call this *once* for any given
 * lease.
 */
static
void nfsd_break_deleg_cb(struct file_lock *fl)
{
        struct nfs4_delegation *dp = (struct nfs4_delegation *)fl->fl_owner;

        dprintk("NFSD nfsd_break_deleg_cb: dp %p fl %p\n",dp,fl);
        if (!dp)
                return;

        /* 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);

        spin_lock(&recall_lock);
        list_add_tail(&dp->dl_recall_lru, &del_recall_lru);
        spin_unlock(&recall_lock);

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

        /*
         * We don't want the locks code to timeout the lease for us;
         * we'll remove it ourself if the delegation isn't returned
         * in time.
         */
        fl->fl_break_time = 0;

        dp->dl_file->fi_had_conflict = true;
        nfsd4_cb_recall(dp);
}

/*
 * The file_lock is being reapd.
 *
 * Called by locks_free_lock() with lock_kernel() held.
 */
static
void nfsd_release_deleg_cb(struct file_lock *fl)
{
        struct nfs4_delegation *dp = (struct nfs4_delegation *)fl->fl_owner;

        dprintk("NFSD nfsd_release_deleg_cb: fl %p dp %p dl_count %d\n", fl,dp, atomic_read(&dp->dl_count));

        if (!(fl->fl_flags & FL_LEASE) || !dp)
                return;
        dp->dl_flock = NULL;
}

/*
 * Set the delegation file_lock back pointer.
 *
 * Called from setlease() with lock_kernel() held.
 */
static
void nfsd_copy_lock_deleg_cb(struct file_lock *new, struct file_lock *fl)
{
        struct nfs4_delegation *dp = (struct nfs4_delegation *)new->fl_owner;

        dprintk("NFSD: nfsd_copy_lock_deleg_cb: new fl %p dp %p\n", new, dp);
        if (!dp)
                return;
        dp->dl_flock = new;
}

/*
 * Called from setlease() with lock_kernel() held
 */
static
int nfsd_same_client_deleg_cb(struct file_lock *onlist, struct file_lock *try)
{
        struct nfs4_delegation *onlistd =
                (struct nfs4_delegation *)onlist->fl_owner;
        struct nfs4_delegation *tryd =
                (struct nfs4_delegation *)try->fl_owner;

        if (onlist->fl_lmops != try->fl_lmops)
                return 0;

        return onlistd->dl_client == tryd->dl_client;
}


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 = {
        .fl_break = nfsd_break_deleg_cb,
        .fl_release_private = nfsd_release_deleg_cb,
        .fl_copy_lock = nfsd_copy_lock_deleg_cb,
        .fl_mylease = nfsd_same_client_deleg_cb,
        .fl_change = nfsd_change_deleg_cb,
};


__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_stateowner *sop = NULL;

        if (!check_name(open->op_owner))
                return nfserr_inval;

        if (STALE_CLIENTID(&open->op_clientid))
                return nfserr_stale_clientid;

        strhashval = ownerstr_hashval(clientid->cl_id, open->op_owner);
        sop = find_openstateowner_str(strhashval, open);
        open->op_stateowner = sop;
        if (!sop) {
                /* Make sure the client's lease hasn't expired. */
                clp = find_confirmed_client(clientid);
                if (clp == NULL)
                        return nfserr_expired;
                goto renew;
        }
        /* When sessions are used, skip open sequenceid processing */
        if (nfsd4_has_session(cstate))
                goto renew;
        if (!sop->so_confirmed) {
                /* Replace unconfirmed owners without checking for replay. */
                clp = sop->so_client;
                release_openowner(sop);
                open->op_stateowner = NULL;
                goto renew;
        }
        if (open->op_seqid == sop->so_seqid - 1) {
                if (sop->so_replay.rp_buflen)
                        return nfserr_replay_me;
                /* The original OPEN failed so spectacularly
                 * that we don't even have replay data saved!
                 * Therefore, we have no choice but to continue
                 * processing this OPEN; presumably, we'll
                 * fail again for the same reason.
                 */
                dprintk("nfsd4_process_open1: replay with no replay cache\n");
                goto renew;
        }
        if (open->op_seqid != sop->so_seqid)
                return nfserr_bad_seqid;
renew:
        if (open->op_stateowner == NULL) {
                sop = alloc_init_open_stateowner(strhashval, clp, open);
                if (sop == NULL)
                        return nfserr_resource;
                open->op_stateowner = sop;
        }
        list_del_init(&sop->so_close_lru);
        renew_client(sop->so_client);
        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 struct nfs4_delegation *
find_delegation_file(struct nfs4_file *fp, stateid_t *stid)
{
        struct nfs4_delegation *dp;

        list_for_each_entry(dp, &fp->fi_delegations, dl_perfile) {
                if (dp->dl_stateid.si_stateownerid == stid->si_stateownerid)
                        return dp;
        }
        return NULL;
}

int share_access_to_flags(u32 share_access)
{
        share_access &= ~NFS4_SHARE_WANT_MASK;

        return share_access == NFS4_SHARE_ACCESS_READ ? RD_STATE : WR_STATE;
}

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

        *dp = find_delegation_file(fp, &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 (open->op_claim_type != NFS4_OPEN_CLAIM_DELEGATE_CUR)
                return nfs_ok;
        if (status)
                return status;
        open->op_stateowner->so_confirmed = 1;
        return nfs_ok;
}

static __be32
nfs4_check_open(struct nfs4_file *fp, struct nfsd4_open *open, struct nfs4_stateid **stpp)
{
        struct nfs4_stateid *local;
        __be32 status = nfserr_share_denied;
        struct nfs4_stateowner *sop = open->op_stateowner;

        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 == sop)
                        *stpp = local;
                /* check for conflicting share reservations */
                if (!test_share(local, open))
                        goto out;
        }
        status = 0;
out:
        return status;
}

static inline struct nfs4_stateid *
nfs4_alloc_stateid(void)
{
        return kmem_cache_alloc(stateid_slab, GFP_KERNEL);
}

static __be32
nfs4_new_open(struct svc_rqst *rqstp, struct nfs4_stateid **stpp,
                struct nfs4_delegation *dp,
                struct svc_fh *cur_fh, int flags)
{
        struct nfs4_stateid *stp;

        stp = nfs4_alloc_stateid();
        if (stp == NULL)
                return nfserr_resource;

        if (dp) {
                get_file(dp->dl_vfs_file);
                stp->st_vfs_file = dp->dl_vfs_file;
        } else {
                __be32 status;
                status = nfsd_open(rqstp, cur_fh, S_IFREG, flags,
                                &stp->st_vfs_file);
                if (status) {
                        if (status == nfserr_dropit)
                                status = nfserr_jukebox;
                        kmem_cache_free(stateid_slab, stp);
                        return status;
                }
        }
        *stpp = stp;
        return 0;
}

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 svc_fh *cur_fh, struct nfs4_stateid *stp, struct nfsd4_open *open)
{
        struct file *filp = stp->st_vfs_file;
        struct inode *inode = filp->f_path.dentry->d_inode;
        unsigned int share_access, new_writer;
        u32 op_share_access;
        __be32 status;

        set_access(&share_access, stp->st_access_bmap);
        new_writer = (~share_access) & open->op_share_access
                        & NFS4_SHARE_ACCESS_WRITE;

        if (new_writer) {
                int err = get_write_access(inode);
                if (err)
                        return nfserrno(err);
                err = mnt_want_write(cur_fh->fh_export->ex_path.mnt);
                if (err)
                        return nfserrno(err);
                file_take_write(filp);
        }
        status = nfsd4_truncate(rqstp, cur_fh, open);
        if (status) {
                if (new_writer)
                        put_write_access(inode);
                return status;
        }
        /* remember the open */
        op_share_access = open->op_share_access & ~NFS4_SHARE_WANT_MASK;
        filp->f_mode |= op_share_access;
        __set_bit(op_share_access, &stp->st_access_bmap);
        __set_bit(open->op_share_deny, &stp->st_deny_bmap);

        return nfs_ok;
}


static void
nfs4_set_claim_prev(struct nfsd4_open *open)
{
        open->op_stateowner->so_confirmed = 1;
        open->op_stateowner->so_client->cl_firststate = 1;
}

/*
 * Attempt to hand out a delegation.
 */
static void
nfs4_open_delegation(struct svc_fh *fh, struct nfsd4_open *open, struct nfs4_stateid *stp)
{
        struct nfs4_delegation *dp;
        struct nfs4_stateowner *sop = stp->st_stateowner;
        int cb_up = atomic_read(&sop->so_client->cl_cb_set);
        struct file_lock fl, *flp = &fl;
        int status, flag = 0;

        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 || !sop->so_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(sop->so_client, stp, fh, flag);
        if (dp == NULL) {
                flag = NFS4_OPEN_DELEGATE_NONE;
                goto out;
        }
        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;
        fl.fl_file = stp->st_vfs_file;
        fl.fl_pid = current->tgid;

        /* vfs_setlease checks to see if delegation should be handed out.
         * the lock_manager callbacks fl_mylease and fl_change are used
         */
        if ((status = vfs_setlease(stp->st_vfs_file, fl.fl_type, &flp))) {
                dprintk("NFSD: setlease failed [%d], no delegation\n", status);
                unhash_delegation(dp);
                flag = NFS4_OPEN_DELEGATE_NONE;
                goto out;
        }

        memcpy(&open->op_delegate_stateid, &dp->dl_stateid, sizeof(dp->dl_stateid));

        dprintk("NFSD: delegation stateid=" STATEID_FMT "\n",
                STATEID_VAL(&dp->dl_stateid));
out:
        if (open->op_claim_type == NFS4_OPEN_CLAIM_PREVIOUS
                        && flag == NFS4_OPEN_DELEGATE_NONE
                        && open->op_delegate_type != NFS4_OPEN_DELEGATE_NONE)
                dprintk("NFSD: WARNING: refusing delegation reclaim\n");
        open->op_delegate_type = flag;
}

/*
 * 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_file *fp = NULL;
        struct inode *ino = current_fh->fh_dentry->d_inode;
        struct nfs4_stateid *stp = NULL;
        struct nfs4_delegation *dp = NULL;
        __be32 status;

        status = nfserr_inval;
        if (!access_valid(open->op_share_access, resp->cstate.minorversion)
                        || !deny_valid(open->op_share_deny))
                goto out;
        /*
         * 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(fp, open, &dp);
                if (status)
                        goto out;
        } else {
                status = nfserr_bad_stateid;
                if (open->op_claim_type == NFS4_OPEN_CLAIM_DELEGATE_CUR)
                        goto out;
                status = nfserr_resource;
                fp = alloc_init_file(ino);
                if (fp == NULL)
                        goto out;
        }

        /*
         * 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, current_fh, stp, open);
                if (status)
                        goto out;
                update_stateid(&stp->st_stateid);
        } else {
                /* Stateid was not found, this is a new OPEN */
                int flags = 0;
                if (open->op_share_access & NFS4_SHARE_ACCESS_READ)
                        flags |= NFSD_MAY_READ;
                if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE)
                        flags |= NFSD_MAY_WRITE;
                status = nfs4_new_open(rqstp, &stp, dp, current_fh, flags);
                if (status)
                        goto out;
                init_stateid(stp, fp, open);
                status = nfsd4_truncate(rqstp, current_fh, open);
                if (status) {
                        release_open_stateid(stp);
                        goto out;
                }
                if (nfsd4_has_session(&resp->cstate))
                        update_stateid(&stp->st_stateid);
        }
        memcpy(&open->op_stateid, &stp->st_stateid, sizeof(stateid_t));

        if (nfsd4_has_session(&resp->cstate))
                open->op_stateowner->so_confirmed = 1;

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

        status = nfs_ok;

        dprintk("%s: stateid=" STATEID_FMT "\n", __func__,
                STATEID_VAL(&stp->st_stateid));
out:
        if (fp)
                put_nfs4_file(fp);
        if (status == 0 && open->op_claim_type == NFS4_OPEN_CLAIM_PREVIOUS)
                nfs4_set_claim_prev(open);
        /*
        * To finish the open response, we just need to set the rflags.
        */
        open->op_rflags = NFS4_OPEN_RESULT_LOCKTYPE_POSIX;
        if (!open->op_stateowner->so_confirmed &&
            !nfsd4_has_session(&resp->cstate))
                open->op_rflags |= NFS4_OPEN_RESULT_CONFIRM;

        return status;
}

__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;
        }
        renew_client(clp);
        status = nfserr_cb_path_down;
        if (!list_empty(&clp->cl_delegations)
                        && !atomic_read(&clp->cl_cb_set))
                goto out;
        status = nfs_ok;
out:
        nfs4_unlock_state();
        return status;
}

struct lock_manager nfsd4_manager = {
};

static void
nfsd4_end_grace(void)
{
        dprintk("NFSD: end of grace period\n");
        nfsd4_recdir_purge_old();
        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_stateowner *sop;
        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");
        if (locks_in_grace())
                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_remove_clid_dir(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;
                }
                dprintk("NFSD: purging unused delegation dp %p, fp %p\n",
                                    dp, dp->dl_flock);
                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);
                list_del_init(&dp->dl_recall_lru);
                unhash_delegation(dp);
        }
        test_val = nfsd4_lease;
        list_for_each_safe(pos, next, &close_lru) {
                sop = list_entry(pos, struct nfs4_stateowner, so_close_lru);
                if (time_after((unsigned long)sop->so_time, (unsigned long)cutoff)) {
                        u = sop->so_time - cutoff;
                        if (test_val > u)
                                test_val = u;
                        break;
                }
                dprintk("NFSD: purging unused open stateowner (so_id %d)\n",
                        sop->so_id);
                release_openowner(sop);
        }
        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 struct nfs4_stateowner *
search_close_lru(u32 st_id, int flags)
{
        struct nfs4_stateowner *local = NULL;

        if (flags & CLOSE_STATE) {
                list_for_each_entry(local, &close_lru, so_close_lru) {
                        if (local->so_id == st_id)
                                return local;
                }
        }
        return NULL;
}

static inline int
nfs4_check_fh(struct svc_fh *fhp, struct nfs4_stateid *stp)
{
        return fhp->fh_dentry->d_inode != stp->st_vfs_file->f_path.dentry->d_inode;
}

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

static inline int
access_permit_read(unsigned long access_bmap)
{
        return test_bit(NFS4_SHARE_ACCESS_READ, &access_bmap) ||
                test_bit(NFS4_SHARE_ACCESS_BOTH, &access_bmap) ||
                test_bit(NFS4_SHARE_ACCESS_WRITE, &access_bmap);
}

static inline int
access_permit_write(unsigned long access_bmap)
{
        return test_bit(NFS4_SHARE_ACCESS_WRITE, &access_bmap) ||
                test_bit(NFS4_SHARE_ACCESS_BOTH, &access_bmap);
}

static
__be32 nfs4_check_openmode(struct nfs4_stateid *stp, int flags)
{
        __be32 status = nfserr_openmode;

        if ((flags & WR_STATE) && (!access_permit_write(stp->st_access_bmap)))
                goto out;
        if ((flags & RD_STATE) && (!access_permit_read(stp->st_access_bmap)))
                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 existance 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);
}

static int check_stateid_generation(stateid_t *in, stateid_t *ref, int flags)
{
        /*
         * When sessions are used the stateid generation number is ignored
         * when it is zero.
         */
        if ((flags & HAS_SESSION) && in->si_generation == 0)
                goto out;

        /* If the client sends us a stateid from the future, it's buggy: */
        if (in->si_generation > ref->si_generation)
                return nfserr_bad_stateid;
        /*
         * The following, however, can happen.  For example, if the
         * client sends an open and some IO at the same time, the open
         * may bump si_generation while the IO is still in flight.
         * Thanks to hard links and renames, the client never knows what
         * file an open will affect.  So it could avoid that situation
         * only by serializing all opens and IO from the same open
         * owner.  To recover from the old_stateid error, the client
         * will just have to retry the IO:
         */
        if (in->si_generation < ref->si_generation)
                return nfserr_old_stateid;
out:
        return nfs_ok;
}

static int is_delegation_stateid(stateid_t *stateid)
{
        return stateid->si_fileid == 0;
}

/*
* Checks for stateid operations
*/
__be32
nfs4_preprocess_stateid_op(struct nfsd4_compound_state *cstate,
                           stateid_t *stateid, int flags, struct file **filpp)
{
        struct nfs4_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 (nfsd4_has_session(cstate))
                flags |= HAS_SESSION;

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

        status = nfserr_stale_stateid;
        if (STALE_STATEID(stateid)) 
                goto out;

        status = nfserr_bad_stateid;
        if (is_delegation_stateid(stateid)) {
                dp = find_delegation_stateid(ino, stateid);
                if (!dp)
                        goto out;
                status = check_stateid_generation(stateid, &dp->dl_stateid,
                                                  flags);
                if (status)
                        goto out;
                status = nfs4_check_delegmode(dp, flags);
                if (status)
                        goto out;
                renew_client(dp->dl_client);
                if (filpp)
                        *filpp = dp->dl_vfs_file;
        } else { /* open or lock stateid */
                stp = find_stateid(stateid, flags);
                if (!stp)
                        goto out;
                if (nfs4_check_fh(current_fh, stp))
                        goto out;
                if (!stp->st_stateowner->so_confirmed)
                        goto out;
                status = check_stateid_generation(stateid, &stp->st_stateid,
                                                  flags);
                if (status)
                        goto out;
                status = nfs4_check_openmode(stp, flags);
                if (status)
                        goto out;
                renew_client(stp->st_stateowner->so_client);
                if (filpp)
                        *filpp = stp->st_vfs_file;
        }
        status = nfs_ok;
out:
        return status;
}

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

/* 
 * Checks for sequence id mutating operations. 
 */
static __be32
nfs4_preprocess_seqid_op(struct nfsd4_compound_state *cstate, u32 seqid,
                         stateid_t *stateid, int flags,
                         struct nfs4_stateowner **sopp,
                         struct nfs4_stateid **stpp, struct nfsd4_lock *lock)
{
        struct nfs4_stateid *stp;
        struct nfs4_stateowner *sop;
        struct svc_fh *current_fh = &cstate->current_fh;
        __be32 status;

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

        *stpp = NULL;
        *sopp = NULL;

        if (ZERO_STATEID(stateid) || ONE_STATEID(stateid)) {
                dprintk("NFSD: preprocess_seqid_op: magic stateid!\n");
                return nfserr_bad_stateid;
        }

        if (STALE_STATEID(stateid))
                return nfserr_stale_stateid;

        if (nfsd4_has_session(cstate))
                flags |= HAS_SESSION;

        /*
        * We return BAD_STATEID if filehandle doesn't match stateid, 
        * the confirmed flag is incorrecly set, or the generation 
        * number is incorrect.  
        */
        stp = find_stateid(stateid, flags);
        if (stp == NULL) {
                /*
                 * Also, we should make sure this isn't just the result of
                 * a replayed close:
                 */
                sop = search_close_lru(stateid->si_stateownerid, flags);
                if (sop == NULL)
                        return nfserr_bad_stateid;
                *sopp = sop;
                goto check_replay;
        }

        *stpp = stp;
        *sopp = sop = stp->st_stateowner;

        if (lock) {
                clientid_t *lockclid = &lock->v.new.clientid;
                struct nfs4_client *clp = sop->so_client;
                int lkflg = 0;
                __be32 status;

                lkflg = setlkflg(lock->lk_type);

                if (lock->lk_is_new) {
                        if (!sop->so_is_open_owner)
                                return nfserr_bad_stateid;
                        if (!(flags & HAS_SESSION) &&
                            !same_clid(&clp->cl_clientid, lockclid))
                                return nfserr_bad_stateid;
                        /* stp is the open stateid */
                        status = nfs4_check_openmode(stp, lkflg);
                        if (status)
                                return status;
                } else {
                        /* stp is the lock stateid */
                        status = nfs4_check_openmode(stp->st_openstp, lkflg);
                        if (status)
                                return status;
               }
        }

        if (nfs4_check_fh(current_fh, stp)) {
                dprintk("NFSD: preprocess_seqid_op: fh-stateid mismatch!\n");
                return nfserr_bad_stateid;
        }

        /*
        *  We now validate the seqid and stateid generation numbers.
        *  For the moment, we ignore the possibility of 
        *  generation number wraparound.
        */
        if (!(flags & HAS_SESSION) && seqid != sop->so_seqid)
                goto check_replay;

        if (sop->so_confirmed && flags & CONFIRM) {
                dprintk("NFSD: preprocess_seqid_op: expected"
                                " unconfirmed stateowner!\n");
                return nfserr_bad_stateid;
        }
        if (!sop->so_confirmed && !(flags & CONFIRM)) {
                dprintk("NFSD: preprocess_seqid_op: stateowner not"
                                " confirmed yet!\n");
                return nfserr_bad_stateid;
        }
        status = check_stateid_generation(stateid, &stp->st_stateid, flags);
        if (status)
                return status;
        renew_client(sop->so_client);
        return nfs_ok;

check_replay:
        if (seqid == sop->so_seqid - 1) {
                dprintk("NFSD: preprocess_seqid_op: retransmission?\n");
                /* indicate replay to calling function */
                return nfserr_replay_me;
        }
        dprintk("NFSD: preprocess_seqid_op: bad seqid (expected %d, got %d)\n",
                        sop->so_seqid, seqid);
        *sopp = NULL;
        return nfserr_bad_seqid;
}

__be32
nfsd4_open_confirm(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                   struct nfsd4_open_confirm *oc)
{
        __be32 status;
        struct nfs4_stateowner *sop;
        struct nfs4_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();

        if ((status = nfs4_preprocess_seqid_op(cstate,
                                        oc->oc_seqid, &oc->oc_req_stateid,
                                        CONFIRM | OPEN_STATE,
                                        &oc->oc_stateowner, &stp, NULL)))
                goto out; 

        sop = oc->oc_stateowner;
        sop->so_confirmed = 1;
        update_stateid(&stp->st_stateid);
        memcpy(&oc->oc_resp_stateid, &stp->st_stateid, sizeof(stateid_t));
        dprintk("NFSD: %s: success, seqid=%d stateid=" STATEID_FMT "\n",
                __func__, oc->oc_seqid, STATEID_VAL(&stp->st_stateid));

        nfsd4_create_clid_dir(sop->so_client);
out:
        if (oc->oc_stateowner) {
                nfs4_get_stateowner(oc->oc_stateowner);
                cstate->replay_owner = oc->oc_stateowner;
        }
        nfs4_unlock_state();
        return status;
}


/*
 * unset all bits in union bitmap (bmap) that
 * do not exist in share (from successful OPEN_DOWNGRADE)
 */
static void
reset_union_bmap_access(unsigned long access, unsigned long *bmap)
{
        int i;
        for (i = 1; i < 4; i++) {
                if ((i & access) != i)
                        __clear_bit(i, bmap);
        }
}

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

__be32
nfsd4_open_downgrade(struct svc_rqst *rqstp,
                     struct nfsd4_compound_state *cstate,
                     struct nfsd4_open_downgrade *od)
{
        __be32 status;
        struct nfs4_stateid *stp;
        unsigned int share_access;

        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);

        if (!access_valid(od->od_share_access, cstate->minorversion)
                        || !deny_valid(od->od_share_deny))
                return nfserr_inval;

        nfs4_lock_state();
        if ((status = nfs4_preprocess_seqid_op(cstate,
                                        od->od_seqid,
                                        &od->od_stateid, 
                                        OPEN_STATE,
                                        &od->od_stateowner, &stp, NULL)))
                goto out; 

        status = nfserr_inval;
        if (!test_bit(od->od_share_access, &stp->st_access_bmap)) {
                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_bit(od->od_share_deny, &stp->st_deny_bmap)) {
                dprintk("NFSD:deny not a subset current bitmap: 0x%lx, input deny=%08x\n",
                        stp->st_deny_bmap, od->od_share_deny);
                goto out;
        }
        set_access(&share_access, stp->st_access_bmap);
        nfs4_file_downgrade(stp->st_vfs_file,
                            share_access & ~od->od_share_access);

        reset_union_bmap_access(od->od_share_access, &stp->st_access_bmap);
        reset_union_bmap_deny(od->od_share_deny, &stp->st_deny_bmap);

        update_stateid(&stp->st_stateid);
        memcpy(&od->od_stateid, &stp->st_stateid, sizeof(stateid_t));
        status = nfs_ok;
out:
        if (od->od_stateowner) {
                nfs4_get_stateowner(od->od_stateowner);
                cstate->replay_owner = od->od_stateowner;
        }
        nfs4_unlock_state();
        return status;
}

/*
 * 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_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();
        /* check close_lru for replay */
        if ((status = nfs4_preprocess_seqid_op(cstate,
                                        close->cl_seqid,
                                        &close->cl_stateid, 
                                        OPEN_STATE | CLOSE_STATE,
                                        &close->cl_stateowner, &stp, NULL)))
                goto out; 
        status = nfs_ok;
        update_stateid(&stp->st_stateid);
        memcpy(&close->cl_stateid, &stp->st_stateid, sizeof(stateid_t));

        /* release_stateid() calls nfsd_close() if needed */
        release_open_stateid(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(&close->cl_stateowner->so_stateids))
                move_to_close_lru(close->cl_stateowner);
out:
        if (close->cl_stateowner) {
                nfs4_get_stateowner(close->cl_stateowner);
                cstate->replay_owner = close->cl_stateowner;
        }
        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 inode *inode;
        __be32 status;
        int flags = 0;

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

        if (nfsd4_has_session(cstate))
                flags |= HAS_SESSION;
        nfs4_lock_state();
        status = nfserr_bad_stateid;
        if (ZERO_STATEID(stateid) || ONE_STATEID(stateid))
                goto out;
        status = nfserr_stale_stateid;
        if (STALE_STATEID(stateid))
                goto out;
        status = nfserr_bad_stateid;
        if (!is_delegation_stateid(stateid))
                goto out;
        dp = find_delegation_stateid(inode, stateid);
        if (!dp)
                goto out;
        status = check_stateid_generation(stateid, &dp->dl_stateid, flags);
        if (status)
                goto out;
        renew_client(dp->dl_client);

        unhash_delegation(dp);
out:
        nfs4_unlock_state();

        return status;
}


/* 
 * Lock owner state (byte-range locks)
 */
#define LOFF_OVERFLOW(start, len)      ((u64)(len) > ~(u64)(start))
#define LOCK_HASH_BITS              8
#define LOCK_HASH_SIZE             (1 << LOCK_HASH_BITS)
#define LOCK_HASH_MASK             (LOCK_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;
}

#define lockownerid_hashval(id) \
        ((id) & LOCK_HASH_MASK)

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

static struct list_head lock_ownerid_hashtbl[LOCK_HASH_SIZE];
static struct list_head lock_ownerstr_hashtbl[LOCK_HASH_SIZE];
static struct list_head lockstateid_hashtbl[STATEID_HASH_SIZE];

static struct nfs4_stateid *
find_stateid(stateid_t *stid, int flags)
{
        struct nfs4_stateid *local;
        u32 st_id = stid->si_stateownerid;
        u32 f_id = stid->si_fileid;
        unsigned int hashval;

        dprintk("NFSD: find_stateid flags 0x%x\n",flags);
        if (flags & (LOCK_STATE | RD_STATE | WR_STATE)) {
                hashval = stateid_hashval(st_id, f_id);
                list_for_each_entry(local, &lockstateid_hashtbl[hashval], st_hash) {
                        if ((local->st_stateid.si_stateownerid == st_id) &&
                            (local->st_stateid.si_fileid == f_id))
                                return local;
                }
        } 

        if (flags & (OPEN_STATE | RD_STATE | WR_STATE)) {
                hashval = stateid_hashval(st_id, f_id);
                list_for_each_entry(local, &stateid_hashtbl[hashval], st_hash) {
                        if ((local->st_stateid.si_stateownerid == st_id) &&
                            (local->st_stateid.si_fileid == f_id))
                                return local;
                }
        }
        return NULL;
}

static struct nfs4_delegation *
find_delegation_stateid(struct inode *ino, stateid_t *stid)
{
        struct nfs4_file *fp;
        struct nfs4_delegation *dl;

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

        fp = find_file(ino);
        if (!fp)
                return NULL;
        dl = find_delegation_file(fp, stid);
        put_nfs4_file(fp);
        return dl;
}

/*
 * 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_stateowner *sop;
        unsigned int hval;

        if (fl->fl_lmops == &nfsd_posix_mng_ops) {
                sop = (struct nfs4_stateowner *) fl->fl_owner;
                hval = lockownerid_hashval(sop->so_id);
                kref_get(&sop->so_ref);
                deny->ld_sop = sop;
                deny->ld_clientid = sop->so_client->cl_clientid;
        } else {
                deny->ld_sop = NULL;
                deny->ld_clientid.cl_boot = 0;
                deny->ld_clientid.cl_id = 0;
        }
        deny->ld_start = fl->fl_start;
        deny->ld_length = NFS4_MAX_UINT64;
        if (fl->fl_end != NFS4_MAX_UINT64)
                deny->ld_length = fl->fl_end - fl->fl_start + 1;        
        deny->ld_type = NFS4_READ_LT;
        if (fl->fl_type != F_RDLCK)
                deny->ld_type = NFS4_WRITE_LT;
}

static struct nfs4_stateowner *
find_lockstateowner_str(struct inode *inode, clientid_t *clid,
                struct xdr_netobj *owner)
{
        unsigned int hashval = lock_ownerstr_hashval(inode, clid->cl_id, owner);
        struct nfs4_stateowner *op;

        list_for_each_entry(op, &lock_ownerstr_hashtbl[hashval], so_strhash) {
                if (same_owner_str(op, owner, clid))
                        return op;
        }
        return NULL;
}

/*
 * Alloc a lock owner structure.
 * Called in nfsd4_lock - therefore, OPEN and OPEN_CONFIRM (if needed) has 
 * occured. 
 *
 * strhashval = lock_ownerstr_hashval 
 */

static struct nfs4_stateowner *
alloc_init_lock_stateowner(unsigned int strhashval, struct nfs4_client *clp, struct nfs4_stateid *open_stp, struct nfsd4_lock *lock) {
        struct nfs4_stateowner *sop;
        struct nfs4_replay *rp;
        unsigned int idhashval;

        if (!(sop = alloc_stateowner(&lock->lk_new_owner)))
                return NULL;
        idhashval = lockownerid_hashval(current_ownerid);
        INIT_LIST_HEAD(&sop->so_idhash);
        INIT_LIST_HEAD(&sop->so_strhash);
        INIT_LIST_HEAD(&sop->so_perclient);
        INIT_LIST_HEAD(&sop->so_stateids);
        INIT_LIST_HEAD(&sop->so_perstateid);
        INIT_LIST_HEAD(&sop->so_close_lru); /* not used */
        sop->so_time = 0;
        list_add(&sop->so_idhash, &lock_ownerid_hashtbl[idhashval]);
        list_add(&sop->so_strhash, &lock_ownerstr_hashtbl[strhashval]);
        list_add(&sop->so_perstateid, &open_stp->st_lockowners);
        sop->so_is_open_owner = 0;
        sop->so_id = current_ownerid++;
        sop->so_client = clp;
        /* It is the openowner seqid that will be incremented in encode in the
         * case of new lockowners; so increment the lock seqid manually: */
        sop->so_seqid = lock->lk_new_lock_seqid + 1;
        sop->so_confirmed = 1;
        rp = &sop->so_replay;
        rp->rp_status = nfserr_serverfault;
        rp->rp_buflen = 0;
        rp->rp_buf = rp->rp_ibuf;
        return sop;
}

static struct nfs4_stateid *
alloc_init_lock_stateid(struct nfs4_stateowner *sop, struct nfs4_file *fp, struct nfs4_stateid *open_stp)
{
        struct nfs4_stateid *stp;
        unsigned int hashval = stateid_hashval(sop->so_id, fp->fi_id);

        stp = nfs4_alloc_stateid();
        if (stp == NULL)
                goto out;
        INIT_LIST_HEAD(&stp->st_hash);
        INIT_LIST_HEAD(&stp->st_perfile);
        INIT_LIST_HEAD(&stp->st_perstateowner);
        INIT_LIST_HEAD(&stp->st_lockowners); /* not used */
        list_add(&stp->st_hash, &lockstateid_hashtbl[hashval]);
        list_add(&stp->st_perfile, &fp->fi_stateids);
        list_add(&stp->st_perstateowner, &sop->so_stateids);
        stp->st_stateowner = sop;
        get_nfs4_file(fp);
        stp->st_file = fp;
        stp->st_stateid.si_boot = boot_time;
        stp->st_stateid.si_stateownerid = sop->so_id;
        stp->st_stateid.si_fileid = fp->fi_id;
        stp->st_stateid.si_generation = 0;
        stp->st_vfs_file = open_stp->st_vfs_file; /* FIXME refcount?? */
        stp->st_access_bmap = open_stp->st_access_bmap;
        stp->st_deny_bmap = open_stp->st_deny_bmap;
        stp->st_openstp = open_stp;

out:
        return stp;
}

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

/*
 *  LOCK operation 
 */
__be32
nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
           struct nfsd4_lock *lock)
{
        struct nfs4_stateowner *open_sop = NULL;
        struct nfs4_stateowner *lock_sop = NULL;
        struct nfs4_stateid *lock_stp;
        struct file *filp;
        struct file_lock file_lock;
        struct file_lock conflock;
        __be32 status = 0;
        unsigned int strhashval;
        unsigned int cmd;
        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_stateid *open_stp = NULL;
                struct nfs4_file *fp;
                
                status = nfserr_stale_clientid;
                if (!nfsd4_has_session(cstate) &&
                    STALE_CLIENTID(&lock->lk_new_clientid))
                        goto out;

                /* validate and update open stateid and open seqid */
                status = nfs4_preprocess_seqid_op(cstate,
                                        lock->lk_new_open_seqid,
                                        &lock->lk_new_open_stateid,
                                        OPEN_STATE,
                                        &lock->lk_replay_owner, &open_stp,
                                        lock);
                if (status)
                        goto out;
                open_sop = lock->lk_replay_owner;
                /* create lockowner and lock stateid */
                fp = open_stp->st_file;
                strhashval = lock_ownerstr_hashval(fp->fi_inode, 
                                open_sop->so_client->cl_clientid.cl_id, 
                                &lock->v.new.owner);
                /* XXX: Do we need to check for duplicate stateowners on
                 * the same file, or should they just be allowed (and
                 * create new stateids)? */
                status = nfserr_resource;
                lock_sop = alloc_init_lock_stateowner(strhashval,
                                open_sop->so_client, open_stp, lock);
                if (lock_sop == NULL)
                        goto out;
                lock_stp = alloc_init_lock_stateid(lock_sop, fp, open_stp);
                if (lock_stp == NULL)
                        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, 
                                       LOCK_STATE,
                                       &lock->lk_replay_owner, &lock_stp, lock);
                if (status)
                        goto out;
                lock_sop = lock->lk_replay_owner;
        }
        /* lock->lk_replay_owner and lock_stp have been created or found */
        filp = lock_stp->st_vfs_file;

        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:
                        file_lock.fl_type = F_RDLCK;
                        cmd = F_SETLK;
                break;
                case NFS4_WRITE_LT:
                case NFS4_WRITEW_LT:
                        file_lock.fl_type = F_WRLCK;
                        cmd = F_SETLK;
                break;
                default:
                        status = nfserr_inval;
                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, cmd, &file_lock, &conflock);
        switch (-err) {
        case 0: /* success! */
                update_stateid(&lock_stp->st_stateid);
                memcpy(&lock->lk_resp_stateid, &lock_stp->st_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 = nfserr_resource;
                break;
        }
out:
        if (status && lock->lk_is_new && lock_sop)
                release_lockowner(lock_sop);
        if (lock->lk_replay_owner) {
                nfs4_get_stateowner(lock->lk_replay_owner);
                cstate->replay_owner = lock->lk_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;
        int error;
        __be32 status;

        if (locks_in_grace())
                return nfserr_grace;

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

        lockt->lt_stateowner = NULL;
        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))) {
                dprintk("NFSD: nfsd4_lockt: fh_verify() failed!\n");
                if (status == nfserr_symlink)
                        status = nfserr_inval;
                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;
        }

        lockt->lt_stateowner = find_lockstateowner_str(inode,
                        &lockt->lt_clientid, &lockt->lt_owner);
        if (lockt->lt_stateowner)
                file_lock.fl_owner = (fl_owner_t)lockt->lt_stateowner;
        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_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();
                                                                                
        if ((status = nfs4_preprocess_seqid_op(cstate,
                                        locku->lu_seqid, 
                                        &locku->lu_stateid, 
                                        LOCK_STATE,
                                        &locku->lu_stateowner, &stp, NULL)))
                goto out;

        filp = stp->st_vfs_file;
        BUG_ON(!filp);
        locks_init_lock(&file_lock);
        file_lock.fl_type = F_UNLCK;
        file_lock.fl_owner = (fl_owner_t) locku->lu_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_stateid);
        memcpy(&locku->lu_stateid, &stp->st_stateid, sizeof(stateid_t));

out:
        if (locku->lu_stateowner) {
                nfs4_get_stateowner(locku->lu_stateowner);
                cstate->replay_owner = locku->lu_stateowner;
        }
        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 file *filp, struct nfs4_stateowner *lowner)
{
        struct file_lock **flpp;
        struct inode *inode = filp->f_path.dentry->d_inode;
        int status = 0;

        lock_kernel();
        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_kernel();
        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_stateid *stp;
        struct xdr_netobj *owner = &rlockowner->rl_owner;
        struct list_head matches;
        int i;
        __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;
        /* XXX: we're doing a linear search through all the lockowners.
         * Yipes!  For now we'll just hope clients aren't really using
         * release_lockowner much, but eventually we have to fix these
         * data structures. */
        INIT_LIST_HEAD(&matches);
        for (i = 0; i < LOCK_HASH_SIZE; i++) {
                list_for_each_entry(sop, &lock_ownerid_hashtbl[i], so_idhash) {
                        if (!same_owner_str(sop, owner, clid))
                                continue;
                        list_for_each_entry(stp, &sop->so_stateids,
                                        st_perstateowner) {
                                if (check_for_locks(stp->st_vfs_file, sop))
                                        goto out;
                                /* Note: so_perclient unused for lockowners,
                                 * so it's OK to fool with here. */
                                list_add(&sop->so_perclient, &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)) {
                sop = list_entry(matches.next, struct nfs4_stateowner,
                                                                so_perclient);
                /* unhash_stateowner deletes so_perclient only
                 * for openowners. */
                list_del(&sop->so_perclient);
                release_lockowner(sop);
        }
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, use_exchange_id);
        return clp ? 1 : 0;
}

/*
 * 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;
}

static 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. */
static struct nfs4_client_reclaim *
nfs4_find_reclaim_client(clientid_t *clid)
{
        unsigned int strhashval;
        struct nfs4_client *clp;
        struct nfs4_client_reclaim *crp = NULL;


        /* find clientid in conf_id_hashtbl */
        clp = find_confirmed_client(clid);
        if (clp == NULL)
                return 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)
{
        return nfs4_find_reclaim_client(clid) ? nfs_ok : nfserr_reclaim_bad;
}

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

int
nfs4_state_init(void)
{
        int i, status;

        status = nfsd4_init_slabs();
        if (status)
                return status;
        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]);
                INIT_LIST_HEAD(&ownerid_hashtbl[i]);
        }
        for (i = 0; i < STATEID_HASH_SIZE; i++) {
                INIT_LIST_HEAD(&stateid_hashtbl[i]);
                INIT_LIST_HEAD(&lockstateid_hashtbl[i]);
        }
        for (i = 0; i < LOCK_HASH_SIZE; i++) {
                INIT_LIST_HEAD(&lock_ownerid_hashtbl[i]);
                INIT_LIST_HEAD(&lock_ownerstr_hashtbl[i]);
        }
        memset(&onestateid, ~0, sizeof(stateid_t));
        INIT_LIST_HEAD(&close_lru);
        INIT_LIST_HEAD(&client_lru);
        INIT_LIST_HEAD(&del_recall_lru);
        reclaim_str_hashtbl_size = 0;
        return 0;
}

static void
nfsd4_load_reboot_recovery_data(void)
{
        int status;

        nfs4_lock_state();
        nfsd4_init_recdir(user_recovery_dirname);
        status = nfsd4_recdir_load();
        nfs4_unlock_state();
        if (status)
                printk("NFSD: Failure reading reboot recovery data\n");
}

/*
 * 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: */

static int
__nfs4_state_start(void)
{
        int ret;

        boot_time = get_seconds();
        locks_start_grace(&nfsd4_manager);
        printk(KERN_INFO "NFSD: starting %ld-second grace period\n",
               nfsd4_grace);
        ret = set_callback_cred();
        if (ret)
                return -ENOMEM;
        laundry_wq = create_singlethread_workqueue("nfsd4");
        if (laundry_wq == NULL)
                return -ENOMEM;
        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);
        return ret;
}

int
nfs4_state_start(void)
{
        nfsd4_load_reboot_recovery_data();
        return __nfs4_state_start();
}

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);
                list_del_init(&dp->dl_recall_lru);
                unhash_delegation(dp);
        }

        nfsd4_shutdown_recdir();
}

void
nfs4_state_shutdown(void)
{
        cancel_rearming_delayed_workqueue(laundry_wq, &laundromat_work);
        destroy_workqueue(laundry_wq);
        locks_end_grace(&nfsd4_manager);
        nfs4_lock_state();
        nfs4_release_reclaim();
        __nfs4_state_shutdown();
        nfsd4_destroy_callback_queue();
        nfs4_unlock_state();
}

/*
 * user_recovery_dirname is protected by the nfsd_mutex since it's only
 * accessed when nfsd is starting.
 */
static void
nfs4_set_recdir(char *recdir)
{
        strcpy(user_recovery_dirname, recdir);
}

/*
 * Change the NFSv4 recovery directory to recdir.
 */
int
nfs4_reset_recoverydir(char *recdir)
{
        int status;
        struct path path;

        status = kern_path(recdir, LOOKUP_FOLLOW, &path);
        if (status)
                return status;
        status = -ENOTDIR;
        if (S_ISDIR(path.dentry->d_inode->i_mode)) {
                nfs4_set_recdir(recdir);
                status = 0;
        }
        path_put(&path);
        return status;
}

char *
nfs4_recoverydir(void)
{
        return user_recovery_dirname;
}