nfs4state.c

Go to the documentation of this file.

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

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

#include "netns.h"

#define NFSDDBG_FACILITY                NFSDDBG_PROC

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

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

static u64 current_sessionid = 1;

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

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

/* Locking: */

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

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

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

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

static void free_session(struct kref *);

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

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

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

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

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

static struct list_head del_recall_lru;

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

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

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

static int num_delegations;
unsigned int max_delegations;

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

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

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

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

static struct list_head ownerstr_hashtbl[OWNER_HASH_SIZE];

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

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

static struct list_head file_hashtbl[FILE_HASH_SIZE];

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

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

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

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

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

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

    error = idr_get_new_above(stateids, stid, min_stateid, &new_stid);
    /*
     * Note: the necessary preallocation was done in
     * nfs4_alloc_stateid().  The idr code caps the number of
     * preallocations that can exist at a time, but the state lock
     * prevents anyone from using ours before we get here:
     */
    BUG_ON(error);
    /*
     * It shouldn't be a problem to reuse an opaque stateid value.
     * I don't think it is for 4.1.  But with 4.0 I worry that, for
     * example, a stray write retransmission could be accepted by
     * the server when it should have been rejected.  Therefore,
     * adopt a trick from the sctp code to attempt to maximize the
     * amount of time until an id is reused, by ensuring they always
     * "increase" (mod INT_MAX):
     */

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

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

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

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

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

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

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

    dprintk("NFSD alloc_init_deleg\n");
    /*
     * Major work on the lease subsystem (for example, to support
     * calbacks on stat) will be required before we can support
     * write delegations properly.
     */
    if (type != NFS4_OPEN_DELEGATE_READ)
        return NULL;
    if (fp->fi_had_conflict)
        return NULL;
    if (num_delegations > max_delegations)
        return NULL;
    dp = delegstateid(nfs4_alloc_stid(clp, deleg_slab));
    if (dp == NULL)
        return dp;
    init_stid(&dp->dl_stid, clp, NFS4_DELEG_STID);
    /*
     * delegation seqid's are never incremented.  The 4.1 special
     * meaning of seqid 0 isn't meaningful, really, but let's avoid
     * 0 anyway just for consistency and use 1:
     */
    dp->dl_stid.sc_stateid.si_generation = 1;
    num_delegations++;
    INIT_LIST_HEAD(&dp->dl_perfile);
    INIT_LIST_HEAD(&dp->dl_perclnt);
    INIT_LIST_HEAD(&dp->dl_recall_lru);
    get_nfs4_file(fp);
    dp->dl_file = fp;
    dp->dl_type = type;
    fh_copy_shallow(&dp->dl_fh, &current_fh->fh_handle);
    dp->dl_time = 0;
    atomic_set(&dp->dl_count, 1);
    INIT_WORK(&dp->dl_recall.cb_work, nfsd4_do_callback_rpc);
    return dp;
}

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

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

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

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

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

/* 
 * SETCLIENTID state 
 */

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    return sid->sequence % SESSION_HASH_SIZE;
}

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


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

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

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

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

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

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

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

    return size;
}

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

    num = min_t(u32, num, NFSD_MAX_SLOTS_PER_SESSION);

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

    return num;
}

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

static struct nfsd4_session *__alloc_session(int slotsize, int numslots)
{
    struct nfsd4_session *new;
    int mem, i;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    nfsd4_hash_conn(conn, ses);
    ret = nfsd4_register_conn(conn);
    if (ret)
        /* oops; xprt is already down: */
        nfsd4_conn_lost(&conn->cn_xpt_user);
    if (conn->cn_flags & NFS4_CDFC4_BACK) {
        /* callback channel may be back up */
        nfsd4_probe_callback(ses->se_client);
    }
}

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

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

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

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

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

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

static void __free_session(struct nfsd4_session *ses)
{
    nfsd4_put_drc_mem(slot_bytes(&ses->se_fchannel), ses->se_fchannel.maxreqs);
    free_session_slots(ses);
    kfree(ses);
}

static void free_session(struct kref *kref)
{
    struct nfsd4_session *ses;

    lockdep_assert_held(&client_lock);
    ses = container_of(kref, struct nfsd4_session, se_ref);
    nfsd4_del_conns(ses);
    __free_session(ses);
}

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

static struct nfsd4_session *alloc_session(struct nfsd4_channel_attrs *fchan)
{
    struct nfsd4_session *new;
    int numslots, slotsize;
    /*
     * Note decreasing slot size below client's request may
     * make it difficult for client to function correctly, whereas
     * decreasing the number of slots will (just?) affect
     * performance.  When short on memory we therefore prefer to
     * decrease number of slots instead of their size.
     */
    slotsize = nfsd4_sanitize_slot_size(fchan->maxresp_cached);
    numslots = nfsd4_get_drc_mem(slotsize, fchan->maxreqs);
    if (numslots < 1)
        return NULL;

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

static struct nfsd4_session *init_session(struct svc_rqst *rqstp, struct nfsd4_session *new, struct nfs4_client *clp, struct nfsd4_create_session *cses)
{
    int idx;

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

    INIT_LIST_HEAD(&new->se_conns);

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

    if (cses->flags & SESSION4_BACK_CHAN) {
        struct sockaddr *sa = svc_addr(rqstp);
        /*
         * This is a little silly; with sessions there's no real
         * use for the callback address.  Use the peer address
         * as a reasonable default for now, but consider fixing
         * the rpc client not to require an address in the
         * future:
         */
        rpc_copy_addr((struct sockaddr *)&clp->cl_cb_conn.cb_addr, sa);
        clp->cl_cb_conn.cb_addrlen = svc_addr_len(sa);
    }
    return new;
}

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

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

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

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

/* must be called under the client_lock */
static inline void
renew_client_locked(struct nfs4_client *clp)
{
    if (is_client_expired(clp)) {
        WARN_ON(1);
        printk("%s: client (clientid %08x/%08x) already expired\n",
            __func__,
            clp->cl_clientid.cl_boot,
            clp->cl_clientid.cl_id);
        return;
    }

    dprintk("renewing client (clientid %08x/%08x)\n", 
            clp->cl_clientid.cl_boot, 
            clp->cl_clientid.cl_id);
    list_move_tail(&clp->cl_lru, &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, struct nfsd_net *nn)
{
    if (clid->cl_boot == nn->boot_time)
        return 0;
    dprintk("NFSD stale clientid (%08x/%08x) boot_time %08lx\n",
        clid->cl_boot, clid->cl_id, nn->boot_time);
    return 1;
}

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

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

static inline void
free_client(struct nfs4_client *clp)
{
    lockdep_assert_held(&client_lock);
    while (!list_empty(&clp->cl_sessions)) {
        struct nfsd4_session *ses;
        ses = list_entry(clp->cl_sessions.next, struct nfsd4_session,
                se_perclnt);
        list_del(&ses->se_perclnt);
        nfsd4_put_session_locked(ses);
    }
    free_svc_cred(&clp->cl_cred);
    kfree(clp->cl_name.data);
    kfree(clp);
}

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

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

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

    mark_client_expired(clp);
    list_del(&clp->cl_lru);
    spin_lock(&clp->cl_lock);
    list_for_each_entry(ses, &clp->cl_sessions, se_perclnt)
        list_del_init(&ses->se_hash);
    spin_unlock(&clp->cl_lock);
}

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

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

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

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

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

static int copy_cred(struct svc_cred *target, struct svc_cred *source)
{
    if (source->cr_principal) {
        target->cr_principal =
                kstrdup(source->cr_principal, GFP_KERNEL);
        if (target->cr_principal == NULL)
            return -ENOMEM;
    } else
        target->cr_principal = NULL;
    target->cr_flavor = source->cr_flavor;
    target->cr_uid = source->cr_uid;
    target->cr_gid = source->cr_gid;
    target->cr_group_info = source->cr_group_info;
    get_group_info(target->cr_group_info);
    return 0;
}

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

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

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

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

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

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


static bool
same_creds(struct svc_cred *cr1, struct svc_cred *cr2)
{
    if ((is_gss_cred(cr1) != is_gss_cred(cr2))
        || (cr1->cr_uid != cr2->cr_uid)
        || (cr1->cr_gid != cr2->cr_gid)
        || !groups_equal(cr1->cr_group_info, cr2->cr_group_info))
        return false;
    if (cr1->cr_principal == cr2->cr_principal)
        return true;
    if (!cr1->cr_principal || !cr2->cr_principal)
        return false;
    return 0 == strcmp(cr1->cr_principal, cr2->cr_principal);
}

static void gen_clid(struct nfs4_client *clp)
{
    static u32 current_clientid = 1;
    struct nfsd_net *nn = net_generic(&init_net, nfsd_net_id);

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

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

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

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

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

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

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

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

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

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

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

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

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

static struct nfs4_client *
find_confirmed_client(clientid_t *clid, bool sessions)
{
    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)) {
            if ((bool)clp->cl_minorversion != sessions)
                return NULL;
            renew_client(clp);
            return clp;
        }
    }
    return NULL;
}

static struct nfs4_client *
find_unconfirmed_client(clientid_t *clid, bool sessions)
{
    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)) {
            if ((bool)clp->cl_minorversion != sessions)
                return NULL;
            return clp;
        }
    }
    return NULL;
}

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

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

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

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

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

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

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

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

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

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

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

    return;
}

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

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

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

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

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

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

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

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

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

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

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

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

    return status;
}

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

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

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

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

__be32
nfsd4_exchange_id(struct svc_rqst *rqstp,
          struct nfsd4_compound_state *cstate,
          struct nfsd4_exchange_id *exid)
{
    struct nfs4_client *unconf, *conf, *new;
    __be32 status;
    unsigned int        strhashval;
    char            dname[HEXDIR_LEN];
    char            addr_str[INET6_ADDRSTRLEN];
    nfs4_verifier       verf = exid->verifier;
    struct sockaddr     *sa = svc_addr(rqstp);
    bool    update = exid->flags & EXCHGID4_FLAG_UPD_CONFIRMED_REC_A;

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

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

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

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

    if (status)
        return status;

    strhashval = clientstr_hashval(dname);

    /* Cases below refer to rfc 5661 section 18.35.4: */
    nfs4_lock_state();
    conf = find_confirmed_client_by_str(dname, strhashval);
    if (conf) {
        bool creds_match = same_creds(&conf->cl_cred, &rqstp->rq_cred);
        bool verfs_match = same_verf(&verf, &conf->cl_verifier);

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

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

    unconf  = find_unconfirmed_client_by_str(dname, strhashval);
    if (unconf) /* case 4, possible retry or client restart */
        expire_client(unconf);

    /* case 1 (normal case) */
out_new:
    new = create_client(exid->clname, dname, rqstp, &verf);
    if (new == NULL) {
        status = nfserr_jukebox;
        goto out;
    }
    new->cl_minorversion = 1;

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

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

out:
    nfs4_unlock_state();
    return status;
}

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

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

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

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

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

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

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

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

    if (cr_ses->flags & ~SESSION4_FLAG_MASK_A)
        return nfserr_inval;
    if (check_forechannel_attrs(cr_ses->fore_channel))
        return nfserr_toosmall;
    new = alloc_session(&cr_ses->fore_channel);
    if (!new)
        return nfserr_jukebox;
    status = nfserr_jukebox;
    conn = alloc_conn_from_crses(rqstp, cr_ses);
    if (!conn)
        goto out_free_session;

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

    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) {
            status = nfsd4_replay_create_session(cr_ses, cs_slot);
            goto out_free_conn;
        } else if (cr_ses->seqid != cs_slot->sl_seqid + 1) {
            status = nfserr_seq_misordered;
            goto out_free_conn;
        }
    } else if (unconf) {
        unsigned int hash;
        struct nfs4_client *old;
        if (!same_creds(&unconf->cl_cred, &rqstp->rq_cred) ||
            !rpc_cmp_addr(sa, (struct sockaddr *) &unconf->cl_addr)) {
            status = nfserr_clid_inuse;
            goto out_free_conn;
        }
        cs_slot = &unconf->cl_cs_slot;
        status = check_slot_seqid(cr_ses->seqid, cs_slot->sl_seqid, 0);
        if (status) {
            /* an unconfirmed replay returns misordered */
            status = nfserr_seq_misordered;
            goto out_free_conn;
        }
        hash = clientstr_hashval(unconf->cl_recdir);
        old = find_confirmed_client_by_str(unconf->cl_recdir, hash);
        if (old)
            expire_client(old);
        move_to_confirmed(unconf);
        conf = unconf;
    } else {
        status = nfserr_stale_clientid;
        goto out_free_conn;
    }
    status = nfs_ok;
    /*
     * We do not support RDMA or persistent sessions
     */
    cr_ses->flags &= ~SESSION4_PERSIST;
    cr_ses->flags &= ~SESSION4_RDMA;

    init_session(rqstp, new, conf, cr_ses);
    nfsd4_init_conn(rqstp, conn, new);

    memcpy(cr_ses->sessionid.data, new->se_sessionid.data,
           NFS4_MAX_SESSIONID_LEN);
    memcpy(&cr_ses->fore_channel, &new->se_fchannel,
        sizeof(struct nfsd4_channel_attrs));
    cs_slot->sl_seqid++;
    cr_ses->seqid = cs_slot->sl_seqid;

    /* cache solo and embedded create sessions under the state lock */
    nfsd4_cache_create_session(cr_ses, cs_slot, status);
out:
    nfs4_unlock_state();
    dprintk("%s returns %d\n", __func__, ntohl(status));
    return status;
out_free_conn:
    free_conn(conn);
out_free_session:
    __free_session(new);
    goto out;
}

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

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

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

__be32 nfsd4_bind_conn_to_session(struct svc_rqst *rqstp,
             struct nfsd4_compound_state *cstate,
             struct nfsd4_bind_conn_to_session *bcts)
{
    __be32 status;
    struct nfsd4_conn *conn;

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

    status = nfsd4_map_bcts_dir(&bcts->dir);
    if (status)
        return status;
    conn = alloc_conn(rqstp, bcts->dir);
    if (!conn)
        return nfserr_jukebox;
    nfsd4_init_conn(rqstp, conn, cstate->session);
    return nfs_ok;
}

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

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

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

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

    unhash_session(ses);
    spin_unlock(&client_lock);

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    nfsd4_sequence_check_conn(conn, session);
    conn = NULL;

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

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

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

        nfsd4_get_session(cstate->session);
        atomic_inc(&clp->cl_refcount);
        switch (clp->cl_cb_state) {
        case NFSD4_CB_DOWN:
            seq->status_flags = SEQ4_STATUS_CB_PATH_DOWN;
            break;
        case NFSD4_CB_FAULT:
            seq->status_flags = SEQ4_STATUS_BACKCHANNEL_FAULT;
            break;
        default:
            seq->status_flags = 0;
        }
    }
    kfree(conn);
    spin_unlock(&client_lock);
    dprintk("%s: return %d\n", __func__, ntohl(status));
    return status;
}

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

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

    if (conf) {
        clp = conf;

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

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

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

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

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

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

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

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

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

    strhashval = clientstr_hashval(dname);

    /* Cases below refer to rfc 3530 section 14.2.33: */
    nfs4_lock_state();
    conf = find_confirmed_client_by_str(dname, strhashval);
    if (conf) {
        /* case 0: */
        status = nfserr_clid_inuse;
        if (clp_used_exchangeid(conf))
            goto out;
        if (!same_creds(&conf->cl_cred, &rqstp->rq_cred)) {
            char addr_str[INET6_ADDRSTRLEN];
            rpc_ntop((struct sockaddr *) &conf->cl_addr, addr_str,
                 sizeof(addr_str));
            dprintk("NFSD: setclientid: string in use by client "
                "at %s\n", addr_str);
            goto out;
        }
    }
    unconf = find_unconfirmed_client_by_str(dname, strhashval);
    if (unconf)
        expire_client(unconf);
    status = nfserr_jukebox;
    new = create_client(clname, dname, rqstp, &clverifier);
    if (new == NULL)
        goto out;
    if (conf && same_verf(&conf->cl_verifier, &clverifier))
        /* case 1: probable callback update */
        copy_clid(new, conf);
    else /* case 4 (new client) or cases 2, 3 (client reboot): */
        gen_clid(new);
    new->cl_minorversion = 0;
    gen_callback(new, setclid, rqstp);
    add_to_unconfirmed(new, strhashval);
    setclid->se_clientid.cl_boot = new->cl_clientid.cl_boot;
    setclid->se_clientid.cl_id = new->cl_clientid.cl_id;
    memcpy(setclid->se_confirm.data, new->cl_confirm.data, sizeof(setclid->se_confirm.data));
    status = nfs_ok;
out:
    nfs4_unlock_state();
    return status;
}


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

    if (STALE_CLIENTID(clid, nn))
        return nfserr_stale_clientid;
    nfs4_lock_state();

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

        conf = find_confirmed_client_by_str(unconf->cl_recdir, hash);
        if (conf)
            expire_client(conf);
        move_to_confirmed(unconf);
        nfsd4_probe_callback(unconf);
    }
out:
    nfs4_unlock_state();
    return status;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

static struct nfs4_openowner *
find_openstateowner_str(unsigned int hashval, struct nfsd4_open *open, bool sessions)
{
    struct nfs4_stateowner *so;
    struct nfs4_openowner *oo;
    struct nfs4_client *clp;

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

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

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

/*
 * Called to check deny when READ with all zero stateid or
 * WRITE with all zero or all one stateid
 */
static __be32
nfs4_share_conflict(struct svc_fh *current_fh, unsigned int deny_type)
{
    struct inode *ino = current_fh->fh_dentry->d_inode;
    struct nfs4_file *fp;
    struct nfs4_ol_stateid *stp;
    __be32 ret;

    dprintk("NFSD: nfs4_share_conflict\n");

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

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

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

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

    nfsd4_cb_recall(dp);
}

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

    BUG_ON(!fp);
    /* We assume break_lease is only called once per lease: */
    BUG_ON(fp->fi_had_conflict);
    /*
     * We don't want the locks code to timeout the lease for us;
     * we'll remove it ourself if a delegation isn't returned
     * in time:
     */
    fl->fl_break_time = 0;

    spin_lock(&recall_lock);
    fp->fi_had_conflict = true;
    list_for_each_entry(dp, &fp->fi_delegations, dl_perfile)
        nfsd_break_one_deleg(dp);
    spin_unlock(&recall_lock);
}

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

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

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

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

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

    strhashval = ownerstr_hashval(clientid->cl_id, &open->op_owner);
    oo = find_openstateowner_str(strhashval, open, cstate->minorversion);
    open->op_openowner = oo;
    if (!oo) {
        clp = find_confirmed_client(clientid, cstate->minorversion);
        if (clp == NULL)
            return nfserr_expired;
        goto new_owner;
    }
    if (!(oo->oo_flags & NFS4_OO_CONFIRMED)) {
        /* Replace unconfirmed owners without checking for replay. */
        clp = oo->oo_owner.so_client;
        release_openowner(oo);
        open->op_openowner = NULL;
        goto new_owner;
    }
    status = nfsd4_check_seqid(cstate, &oo->oo_owner, open->op_seqid);
    if (status)
        return status;
    clp = oo->oo_owner.so_client;
    goto alloc_stateid;
new_owner:
    oo = alloc_init_open_stateowner(strhashval, clp, open);
    if (oo == NULL)
        return nfserr_jukebox;
    open->op_openowner = oo;
alloc_stateid:
    open->op_stp = nfs4_alloc_stateid(clp);
    if (!open->op_stp)
        return nfserr_jukebox;
    return nfs_ok;
}

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

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

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

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

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

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

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

static __be32
nfs4_check_open(struct nfs4_file *fp, struct nfsd4_open *open, struct nfs4_ol_stateid **stpp)
{
    struct nfs4_ol_stateid *local;
    struct nfs4_openowner *oo = open->op_openowner;

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

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

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

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

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

    return nfs_ok;
}

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

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

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

    return nfs_ok;
}


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

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

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

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

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

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

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

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

static void nfsd4_open_deleg_none_ext(struct nfsd4_open *open, int status)
{
    open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE_EXT;
    if (status == -EAGAIN)
        open->op_why_no_deleg = WND4_CONTENTION;
    else {
        open->op_why_no_deleg = WND4_RESOURCE;
        switch (open->op_deleg_want) {
        case NFS4_SHARE_WANT_READ_DELEG:
        case NFS4_SHARE_WANT_WRITE_DELEG:
        case NFS4_SHARE_WANT_ANY_DELEG:
            break;
        case NFS4_SHARE_WANT_CANCEL:
            open->op_why_no_deleg = WND4_CANCELLED;
            break;
        case NFS4_SHARE_WANT_NO_DELEG:
            BUG();  /* not supposed to get here */
        }
    }
}

/*
 * Attempt to hand out a delegation.
 */
static void
nfs4_open_delegation(struct net *net, struct svc_fh *fh,
             struct nfsd4_open *open, struct nfs4_ol_stateid *stp)
{
    struct nfs4_delegation *dp;
    struct nfs4_openowner *oo = container_of(stp->st_stateowner, struct nfs4_openowner, oo_owner);
    int cb_up;
    int status = 0, flag = 0;

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

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

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

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

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

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

/*
 * called with nfs4_lock_state() held.
 */
__be32
nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_open *open)
{
    struct nfsd4_compoundres *resp = rqstp->rq_resp;
    struct nfs4_client *cl = open->op_openowner->oo_owner.so_client;
    struct nfs4_file *fp = NULL;
    struct inode *ino = current_fh->fh_dentry->d_inode;
    struct nfs4_ol_stateid *stp = NULL;
    struct nfs4_delegation *dp = NULL;
    __be32 status;

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

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

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

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

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

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

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

    return status;
}

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

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

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

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

static void
nfsd4_end_grace(struct net *net)
{
    struct nfsd_net *nn = net_generic(net, nfsd_net_id);

    /* do nothing if grace period already ended */
    if (nn->grace_ended)
        return;

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

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

    nfs4_lock_state();

    dprintk("NFSD: laundromat service - starting\n");
    nfsd4_end_grace(&init_net);
    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);
        expire_client(clp);
    }
    spin_lock(&recall_lock);
    list_for_each_safe(pos, next, &del_recall_lru) {
        dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
        if (time_after((unsigned long)dp->dl_time, (unsigned long)cutoff)) {
            u = dp->dl_time - cutoff;
            if (test_val > u)
                test_val = u;
            break;
        }
        list_move(&dp->dl_recall_lru, &reaplist);
    }
    spin_unlock(&recall_lock);
    list_for_each_safe(pos, next, &reaplist) {
        dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
        unhash_delegation(dp);
    }
    test_val = nfsd4_lease;
    list_for_each_safe(pos, next, &close_lru) {
        oo = container_of(pos, struct nfs4_openowner, oo_close_lru);
        if (time_after((unsigned long)oo->oo_time, (unsigned long)cutoff)) {
            u = oo->oo_time - cutoff;
            if (test_val > u)
                test_val = u;
            break;
        }
        release_openowner(oo);
    }
    if (clientid_val < NFSD_LAUNDROMAT_MINTIMEOUT)
        clientid_val = NFSD_LAUNDROMAT_MINTIMEOUT;
    nfs4_unlock_state();
    return clientid_val;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    if (ZERO_STATEID(stateid) || ONE_STATEID(stateid))
        return nfserr_bad_stateid;
    /* Client debugging aid. */
    if (!same_clid(&stateid->si_opaque.so_clid, &cl->cl_clientid)) {
        char addr_str[INET6_ADDRSTRLEN];
        rpc_ntop((struct sockaddr *)&cl->cl_addr, addr_str,
                 sizeof(addr_str));
        pr_warn_ratelimited("NFSD: client %s testing state ID "
                    "with incorrect client ID\n", addr_str);
        return nfserr_bad_stateid;
    }
    s = find_stateid(cl, stateid);
    if (!s)
        return nfserr_bad_stateid;
    status = check_stateid_generation(stateid, &s->sc_stateid, 1);
    if (status)
        return status;
    if (!(s->sc_type & (NFS4_OPEN_STID | NFS4_LOCK_STID)))
        return nfs_ok;
    ols = openlockstateid(s);
    if (ols->st_stateowner->so_is_open_owner
        && !(openowner(ols->st_stateowner)->oo_flags & NFS4_OO_CONFIRMED))
        return nfserr_bad_stateid;
    return nfs_ok;
}

static __be32 nfsd4_lookup_stateid(stateid_t *stateid, unsigned char typemask, struct nfs4_stid **s, bool sessions)
{
    struct nfs4_client *cl;
    struct nfsd_net *nn = net_generic(&init_net, nfsd_net_id);

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

}

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

    if (filpp)
        *filpp = NULL;

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

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

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

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

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

    nfs4_lock_state();
    list_for_each_entry(stateid, &test_stateid->ts_stateid_list, ts_id_list)
        stateid->ts_id_status =
            nfsd4_validate_stateid(cl, &stateid->ts_id_stateid);
    nfs4_unlock_state();

    return nfs_ok;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    nfs4_lock_state();

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

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

static inline void nfs4_stateid_downgrade_bit(struct nfs4_ol_stateid *stp, u32 access)
{
    if (!test_access(access, stp))
        return;
    nfs4_file_put_access(stp->st_file, nfs4_access_to_omode(access));
    clear_access(access, stp);
}

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

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

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

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

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

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

    reset_union_bmap_deny(od->od_share_deny, stp);

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

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

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

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

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

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

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

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

    if (list_empty(&oo->oo_owner.so_stateids)) {
        if (cstate->minorversion) {
            release_openowner(oo);
            cstate->replay_owner = NULL;
        } else {
            /*
             * In the 4.0 case we need to keep the owners around a
             * little while to handle CLOSE replay.
             */
            if (list_empty(&oo->oo_owner.so_stateids))
                move_to_close_lru(oo);
        }
    }
out:
    if (!cstate->replay_owner)
        nfs4_unlock_state();
    return status;
}

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

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

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

    unhash_delegation(dp);
out:
    nfs4_unlock_state();

    return status;
}


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

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

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

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

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

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

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

static struct list_head lockowner_ino_hashtbl[LOCKOWNER_INO_HASH_SIZE];

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

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

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

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

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

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

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

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

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

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

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

static struct nfs4_lockowner *
alloc_init_lock_stateowner(unsigned int strhashval, struct nfs4_client *clp, struct nfs4_ol_stateid *open_stp, struct nfsd4_lock *lock) {
    struct nfs4_lockowner *lo;

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

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

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

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

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

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

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

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

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

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

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

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

    nfs4_lock_state();

    if (lock->lk_is_new) {
        struct nfs4_ol_stateid *open_stp = NULL;

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

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

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

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

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

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

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

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

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

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

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

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

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

    nfs4_lock_state();

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

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

    inode = cstate->current_fh.fh_dentry->d_inode;
    file_lock = locks_alloc_lock();
    if (!file_lock) {
        dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
        status = nfserr_jukebox;
        goto out;
    }
    locks_init_lock(file_lock);
    switch (lockt->lt_type) {
        case NFS4_READ_LT:
        case NFS4_READW_LT:
            file_lock->fl_type = F_RDLCK;
        break;
        case NFS4_WRITE_LT:
        case NFS4_WRITEW_LT:
            file_lock->fl_type = F_WRLCK;
        break;
        default:
            dprintk("NFSD: nfs4_lockt: bad lock type!\n");
            status = nfserr_inval;
        goto out;
    }

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

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

    nfs4_transform_lock_offset(file_lock);

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

    if (file_lock->fl_type != F_UNLCK) {
        status = nfserr_denied;
        nfs4_set_lock_denied(file_lock, &lockt->lt_denied);
    }
out:
    nfs4_unlock_state();
    if (file_lock)
        locks_free_lock(file_lock);
    return status;
}

__be32
nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
        struct nfsd4_locku *locku)
{
    struct nfs4_ol_stateid *stp;
    struct file *filp = NULL;
    struct file_lock *file_lock = NULL;
    __be32 status;
    int err;
                                
    dprintk("NFSD: nfsd4_locku: start=%Ld length=%Ld\n",
        (long long) locku->lu_offset,
        (long long) locku->lu_length);

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

    nfs4_lock_state();
                                            
    status = nfs4_preprocess_seqid_op(cstate, locku->lu_seqid,
                    &locku->lu_stateid, NFS4_LOCK_STID, &stp);
    if (status)
        goto out;
    filp = find_any_file(stp->st_file);
    if (!filp) {
        status = nfserr_lock_range;
        goto out;
    }
    file_lock = locks_alloc_lock();
    if (!file_lock) {
        dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
        status = nfserr_jukebox;
        goto out;
    }
    locks_init_lock(file_lock);
    file_lock->fl_type = F_UNLCK;
    file_lock->fl_owner = (fl_owner_t)lockowner(stp->st_stateowner);
    file_lock->fl_pid = current->tgid;
    file_lock->fl_file = filp;
    file_lock->fl_flags = FL_POSIX;
    file_lock->fl_lmops = &nfsd_posix_mng_ops;
    file_lock->fl_start = locku->lu_offset;

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

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

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

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

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

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

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

    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, nn))
        return status;

    nfs4_lock_state();

    status = nfserr_locks_held;
    INIT_LIST_HEAD(&matches);

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

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

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

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

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

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

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

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

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

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

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

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

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

    return nfsd4_client_record_check(clp) ? nfserr_reclaim_bad : nfs_ok;
}

#ifdef CONFIG_NFSD_FAULT_INJECTION

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

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

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

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

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

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

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

void nfsd_forget_locks(u64 num)
{
    int count;

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

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

void nfsd_forget_openowners(u64 num)
{
    int count;

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

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

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

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

    return count;
}

void nfsd_forget_delegations(u64 num)
{
    unsigned int count;
    LIST_HEAD(victims);
    struct nfs4_delegation *dp, *dnext;

    spin_lock(&recall_lock);
    count = nfsd_process_n_delegations(num, &victims);
    spin_unlock(&recall_lock);

    nfs4_lock_state();
    list_for_each_entry_safe(dp, dnext, &victims, dl_recall_lru)
        unhash_delegation(dp);
    nfs4_unlock_state();

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

void nfsd_recall_delegations(u64 num)
{
    unsigned int count;
    LIST_HEAD(victims);
    struct nfs4_delegation *dp, *dnext;

    spin_lock(&recall_lock);
    count = nfsd_process_n_delegations(num, &victims);
    list_for_each_entry_safe(dp, dnext, &victims, dl_recall_lru) {
        list_del(&dp->dl_recall_lru);
        nfsd_break_one_deleg(dp);
    }
    spin_unlock(&recall_lock);

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

#endif /* CONFIG_NFSD_FAULT_INJECTION */

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

void
nfs4_state_init(void)
{
    int i;

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

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

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

int
nfs4_state_start(void)
{
    struct net *net = &init_net;
    struct nfsd_net *nn = net_generic(net, nfsd_net_id);
    int ret;

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

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

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

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

void
nfs4_state_shutdown(void)
{
    struct net *net = &init_net;
    struct nfsd_net *nn = net_generic(net, nfsd_net_id);

    cancel_delayed_work_sync(&laundromat_work);
    destroy_workqueue(laundry_wq);
    locks_end_grace(&nn->nfsd4_manager);
    nfs4_lock_state();
    __nfs4_state_shutdown();
    nfs4_unlock_state();
    nfsd4_destroy_callback_queue();
}

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

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

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

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

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

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

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

/*
 * functions to consume current state id
 */

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

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

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

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

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

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

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

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