Add LLVM openmp trunk r351319 (just before the release_80 branch point)

[FreeBSD/FreeBSD.git] / sys / fs / nfsclient / nfs_clstate.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2009 Rick Macklem, University of Guelph
 * All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 AUTHOR 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*
 * These functions implement the client side state handling for NFSv4.
 * NFSv4 state handling:
 * - A lockowner is used to determine lock contention, so it
 *   corresponds directly to a Posix pid. (1 to 1 mapping)
 * - The correct granularity of an OpenOwner is not nearly so
 *   obvious. An OpenOwner does the following:
 *   - provides a serial sequencing of Open/Close/Lock-with-new-lockowner
 *   - is used to check for Open/Share contention (not applicable to
 *     this client, since all Opens are Deny_None)
 *   As such, I considered both extreme.
 *   1 OpenOwner per ClientID - Simple to manage, but fully serializes
 *   all Open, Close and Lock (with a new lockowner) Ops.
 *   1 OpenOwner for each Open - This one results in an OpenConfirm for
 *   every Open, for most servers.
 *   So, I chose to use the same mapping as I did for LockOwnwers.
 *   The main concern here is that you can end up with multiple Opens
 *   for the same File Handle, but on different OpenOwners (opens
 *   inherited from parents, grandparents...) and you do not know
 *   which of these the vnodeop close applies to. This is handled by
 *   delaying the Close Op(s) until all of the Opens have been closed.
 *   (It is not yet obvious if this is the correct granularity.)
 * - How the code handles serialization:
 *   - For the ClientId, it uses an exclusive lock while getting its
 *     SetClientId and during recovery. Otherwise, it uses a shared
 *     lock via a reference count.
 *   - For the rest of the data structures, it uses an SMP mutex
 *     (once the nfs client is SMP safe) and doesn't sleep while
 *     manipulating the linked lists.
 *   - The serialization of Open/Close/Lock/LockU falls out in the
 *     "wash", since OpenOwners and LockOwners are both mapped from
 *     Posix pid. In other words, there is only one Posix pid using
 *     any given owner, so that owner is serialized. (If you change
 *     the granularity of the OpenOwner, then code must be added to
 *     serialize Ops on the OpenOwner.)
 * - When to get rid of OpenOwners and LockOwners.
 *   - The function nfscl_cleanup_common() is executed after a process exits.
 *     It goes through the client list looking for all Open and Lock Owners.
 *     When one is found, it is marked "defunct" or in the case of
 *     an OpenOwner without any Opens, freed.
 *     The renew thread scans for defunct Owners and gets rid of them,
 *     if it can. The LockOwners will also be deleted when the
 *     associated Open is closed.
 *   - If the LockU or Close Op(s) fail during close in a way
 *     that could be recovered upon retry, they are relinked to the
 *     ClientId's defunct open list and retried by the renew thread
 *     until they succeed or an unmount/recovery occurs.
 *     (Since we are done with them, they do not need to be recovered.)
 */

#ifndef APPLEKEXT
#include <fs/nfs/nfsport.h>

/*
 * Global variables
 */
extern struct nfsstatsv1 nfsstatsv1;
extern struct nfsreqhead nfsd_reqq;
extern u_int32_t newnfs_false, newnfs_true;
extern int nfscl_debuglevel;
extern int nfscl_enablecallb;
extern int nfs_numnfscbd;
NFSREQSPINLOCK;
NFSCLSTATEMUTEX;
int nfscl_inited = 0;
struct nfsclhead nfsclhead;     /* Head of clientid list */
int nfscl_deleghighwater = NFSCLDELEGHIGHWATER;
int nfscl_layouthighwater = NFSCLLAYOUTHIGHWATER;
#endif  /* !APPLEKEXT */

static int nfscl_delegcnt = 0;
static int nfscl_layoutcnt = 0;
static int nfscl_getopen(struct nfsclownerhead *, u_int8_t *, int, u_int8_t *,
    u_int8_t *, u_int32_t, struct nfscllockowner **, struct nfsclopen **);
static void nfscl_clrelease(struct nfsclclient *);
static void nfscl_cleanclient(struct nfsclclient *);
static void nfscl_expireclient(struct nfsclclient *, struct nfsmount *,
    struct ucred *, NFSPROC_T *);
static int nfscl_expireopen(struct nfsclclient *, struct nfsclopen *,
    struct nfsmount *, struct ucred *, NFSPROC_T *);
static void nfscl_recover(struct nfsclclient *, struct ucred *, NFSPROC_T *);
static void nfscl_insertlock(struct nfscllockowner *, struct nfscllock *,
    struct nfscllock *, int);
static int nfscl_updatelock(struct nfscllockowner *, struct nfscllock **,
    struct nfscllock **, int);
static void nfscl_delegreturnall(struct nfsclclient *, NFSPROC_T *);
static u_int32_t nfscl_nextcbident(void);
static mount_t nfscl_getmnt(int, uint8_t *, u_int32_t, struct nfsclclient **);
static struct nfsclclient *nfscl_getclnt(u_int32_t);
static struct nfsclclient *nfscl_getclntsess(uint8_t *);
static struct nfscldeleg *nfscl_finddeleg(struct nfsclclient *, u_int8_t *,
    int);
static void nfscl_retoncloselayout(vnode_t, struct nfsclclient *, uint8_t *,
    int, struct nfsclrecalllayout **);
static void nfscl_reldevinfo_locked(struct nfscldevinfo *);
static struct nfscllayout *nfscl_findlayout(struct nfsclclient *, u_int8_t *,
    int);
static struct nfscldevinfo *nfscl_finddevinfo(struct nfsclclient *, uint8_t *);
static int nfscl_checkconflict(struct nfscllockownerhead *, struct nfscllock *,
    u_int8_t *, struct nfscllock **);
static void nfscl_freealllocks(struct nfscllockownerhead *, int);
static int nfscl_localconflict(struct nfsclclient *, u_int8_t *, int,
    struct nfscllock *, u_int8_t *, struct nfscldeleg *, struct nfscllock **);
static void nfscl_newopen(struct nfsclclient *, struct nfscldeleg *,
    struct nfsclowner **, struct nfsclowner **, struct nfsclopen **,
    struct nfsclopen **, u_int8_t *, u_int8_t *, int, struct ucred *, int *);
static int nfscl_moveopen(vnode_t , struct nfsclclient *,
    struct nfsmount *, struct nfsclopen *, struct nfsclowner *,
    struct nfscldeleg *, struct ucred *, NFSPROC_T *);
static void nfscl_totalrecall(struct nfsclclient *);
static int nfscl_relock(vnode_t , struct nfsclclient *, struct nfsmount *,
    struct nfscllockowner *, struct nfscllock *, struct ucred *, NFSPROC_T *);
static int nfscl_tryopen(struct nfsmount *, vnode_t , u_int8_t *, int,
    u_int8_t *, int, u_int32_t, struct nfsclopen *, u_int8_t *, int,
    struct nfscldeleg **, int, u_int32_t, struct ucred *, NFSPROC_T *);
static int nfscl_trylock(struct nfsmount *, vnode_t , u_int8_t *,
    int, struct nfscllockowner *, int, int, u_int64_t, u_int64_t, short,
    struct ucred *, NFSPROC_T *);
static int nfsrpc_reopen(struct nfsmount *, u_int8_t *, int, u_int32_t,
    struct nfsclopen *, struct nfscldeleg **, struct ucred *, NFSPROC_T *);
static void nfscl_freedeleg(struct nfscldeleghead *, struct nfscldeleg *);
static int nfscl_errmap(struct nfsrv_descript *, u_int32_t);
static void nfscl_cleanup_common(struct nfsclclient *, u_int8_t *);
static int nfscl_recalldeleg(struct nfsclclient *, struct nfsmount *,
    struct nfscldeleg *, vnode_t, struct ucred *, NFSPROC_T *, int);
static void nfscl_freeopenowner(struct nfsclowner *, int);
static void nfscl_cleandeleg(struct nfscldeleg *);
static int nfscl_trydelegreturn(struct nfscldeleg *, struct ucred *,
    struct nfsmount *, NFSPROC_T *);
static void nfscl_emptylockowner(struct nfscllockowner *,
    struct nfscllockownerfhhead *);
static void nfscl_mergeflayouts(struct nfsclflayouthead *,
    struct nfsclflayouthead *);
static int nfscl_layoutrecall(int, struct nfscllayout *, uint32_t, uint64_t,
    uint64_t, uint32_t, uint32_t, uint32_t, char *, struct nfsclrecalllayout *);
static int nfscl_seq(uint32_t, uint32_t);
static void nfscl_layoutreturn(struct nfsmount *, struct nfscllayout *,
    struct ucred *, NFSPROC_T *);
static void nfscl_dolayoutcommit(struct nfsmount *, struct nfscllayout *,
    struct ucred *, NFSPROC_T *);

static short nfscberr_null[] = {
        0,
        0,
};

static short nfscberr_getattr[] = {
        NFSERR_RESOURCE,
        NFSERR_BADHANDLE,
        NFSERR_BADXDR,
        NFSERR_RESOURCE,
        NFSERR_SERVERFAULT,
        0,
};

static short nfscberr_recall[] = {
        NFSERR_RESOURCE,
        NFSERR_BADHANDLE,
        NFSERR_BADSTATEID,
        NFSERR_BADXDR,
        NFSERR_RESOURCE,
        NFSERR_SERVERFAULT,
        0,
};

static short *nfscl_cberrmap[] = {
        nfscberr_null,
        nfscberr_null,
        nfscberr_null,
        nfscberr_getattr,
        nfscberr_recall
};

#define NETFAMILY(clp) \
                (((clp)->nfsc_flags & NFSCLFLAGS_AFINET6) ? AF_INET6 : AF_INET)

/*
 * Called for an open operation.
 * If the nfhp argument is NULL, just get an openowner.
 */
APPLESTATIC int
nfscl_open(vnode_t vp, u_int8_t *nfhp, int fhlen, u_int32_t amode, int usedeleg,
    struct ucred *cred, NFSPROC_T *p, struct nfsclowner **owpp,
    struct nfsclopen **opp, int *newonep, int *retp, int lockit)
{
        struct nfsclclient *clp;
        struct nfsclowner *owp, *nowp;
        struct nfsclopen *op = NULL, *nop = NULL;
        struct nfscldeleg *dp;
        struct nfsclownerhead *ohp;
        u_int8_t own[NFSV4CL_LOCKNAMELEN];
        int ret;

        if (newonep != NULL)
                *newonep = 0;
        if (opp != NULL)
                *opp = NULL;
        if (owpp != NULL)
                *owpp = NULL;

        /*
         * Might need one or both of these, so MALLOC them now, to
         * avoid a tsleep() in MALLOC later.
         */
        nowp = malloc(sizeof (struct nfsclowner),
            M_NFSCLOWNER, M_WAITOK);
        if (nfhp != NULL)
            nop = malloc(sizeof (struct nfsclopen) +
                fhlen - 1, M_NFSCLOPEN, M_WAITOK);
        ret = nfscl_getcl(vnode_mount(vp), cred, p, 1, &clp);
        if (ret != 0) {
                free(nowp, M_NFSCLOWNER);
                if (nop != NULL)
                        free(nop, M_NFSCLOPEN);
                return (ret);
        }

        /*
         * Get the Open iff it already exists.
         * If none found, add the new one or return error, depending upon
         * "create".
         */
        NFSLOCKCLSTATE();
        dp = NULL;
        /* First check the delegation list */
        if (nfhp != NULL && usedeleg) {
                LIST_FOREACH(dp, NFSCLDELEGHASH(clp, nfhp, fhlen), nfsdl_hash) {
                        if (dp->nfsdl_fhlen == fhlen &&
                            !NFSBCMP(nfhp, dp->nfsdl_fh, fhlen)) {
                                if (!(amode & NFSV4OPEN_ACCESSWRITE) ||
                                    (dp->nfsdl_flags & NFSCLDL_WRITE))
                                        break;
                                dp = NULL;
                                break;
                        }
                }
        }

        if (dp != NULL) {
                nfscl_filllockowner(p->td_proc, own, F_POSIX);
                ohp = &dp->nfsdl_owner;
        } else {
                /* For NFSv4.1 and this option, use a single open_owner. */
                if (NFSHASONEOPENOWN(VFSTONFS(vnode_mount(vp))))
                        nfscl_filllockowner(NULL, own, F_POSIX);
                else
                        nfscl_filllockowner(p->td_proc, own, F_POSIX);
                ohp = &clp->nfsc_owner;
        }
        /* Now, search for an openowner */
        LIST_FOREACH(owp, ohp, nfsow_list) {
                if (!NFSBCMP(owp->nfsow_owner, own, NFSV4CL_LOCKNAMELEN))
                        break;
        }

        /*
         * Create a new open, as required.
         */
        nfscl_newopen(clp, dp, &owp, &nowp, &op, &nop, own, nfhp, fhlen,
            cred, newonep);

        /*
         * Now, check the mode on the open and return the appropriate
         * value.
         */
        if (retp != NULL) {
                if (nfhp != NULL && dp != NULL && nop == NULL)
                        /* new local open on delegation */
                        *retp = NFSCLOPEN_SETCRED;
                else
                        *retp = NFSCLOPEN_OK;
        }
        if (op != NULL && (amode & ~(op->nfso_mode))) {
                op->nfso_mode |= amode;
                if (retp != NULL && dp == NULL)
                        *retp = NFSCLOPEN_DOOPEN;
        }

        /*
         * Serialize modifications to the open owner for multiple threads
         * within the same process using a read/write sleep lock.
         * For NFSv4.1 and a single OpenOwner, allow concurrent open operations
         * by acquiring a shared lock.  The close operations still use an
         * exclusive lock for this case.
         */
        if (lockit != 0) {
                if (NFSHASONEOPENOWN(VFSTONFS(vnode_mount(vp)))) {
                        /*
                         * Get a shared lock on the OpenOwner, but first
                         * wait for any pending exclusive lock, so that the
                         * exclusive locker gets priority.
                         */
                        nfsv4_lock(&owp->nfsow_rwlock, 0, NULL,
                            NFSCLSTATEMUTEXPTR, NULL);
                        nfsv4_getref(&owp->nfsow_rwlock, NULL,
                            NFSCLSTATEMUTEXPTR, NULL);
                } else
                        nfscl_lockexcl(&owp->nfsow_rwlock, NFSCLSTATEMUTEXPTR);
        }
        NFSUNLOCKCLSTATE();
        if (nowp != NULL)
                free(nowp, M_NFSCLOWNER);
        if (nop != NULL)
                free(nop, M_NFSCLOPEN);
        if (owpp != NULL)
                *owpp = owp;
        if (opp != NULL)
                *opp = op;
        return (0);
}

/*
 * Create a new open, as required.
 */
static void
nfscl_newopen(struct nfsclclient *clp, struct nfscldeleg *dp,
    struct nfsclowner **owpp, struct nfsclowner **nowpp, struct nfsclopen **opp,
    struct nfsclopen **nopp, u_int8_t *own, u_int8_t *fhp, int fhlen,
    struct ucred *cred, int *newonep)
{
        struct nfsclowner *owp = *owpp, *nowp;
        struct nfsclopen *op, *nop;

        if (nowpp != NULL)
                nowp = *nowpp;
        else
                nowp = NULL;
        if (nopp != NULL)
                nop = *nopp;
        else
                nop = NULL;
        if (owp == NULL && nowp != NULL) {
                NFSBCOPY(own, nowp->nfsow_owner, NFSV4CL_LOCKNAMELEN);
                LIST_INIT(&nowp->nfsow_open);
                nowp->nfsow_clp = clp;
                nowp->nfsow_seqid = 0;
                nowp->nfsow_defunct = 0;
                nfscl_lockinit(&nowp->nfsow_rwlock);
                if (dp != NULL) {
                        nfsstatsv1.cllocalopenowners++;
                        LIST_INSERT_HEAD(&dp->nfsdl_owner, nowp, nfsow_list);
                } else {
                        nfsstatsv1.clopenowners++;
                        LIST_INSERT_HEAD(&clp->nfsc_owner, nowp, nfsow_list);
                }
                owp = *owpp = nowp;
                *nowpp = NULL;
                if (newonep != NULL)
                        *newonep = 1;
        }

         /* If an fhp has been specified, create an Open as well. */
        if (fhp != NULL) {
                /* and look for the correct open, based upon FH */
                LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                        if (op->nfso_fhlen == fhlen &&
                            !NFSBCMP(op->nfso_fh, fhp, fhlen))
                                break;
                }
                if (op == NULL && nop != NULL) {
                        nop->nfso_own = owp;
                        nop->nfso_mode = 0;
                        nop->nfso_opencnt = 0;
                        nop->nfso_posixlock = 1;
                        nop->nfso_fhlen = fhlen;
                        NFSBCOPY(fhp, nop->nfso_fh, fhlen);
                        LIST_INIT(&nop->nfso_lock);
                        nop->nfso_stateid.seqid = 0;
                        nop->nfso_stateid.other[0] = 0;
                        nop->nfso_stateid.other[1] = 0;
                        nop->nfso_stateid.other[2] = 0;
                        KASSERT(cred != NULL, ("%s: cred NULL\n", __func__));
                        newnfs_copyincred(cred, &nop->nfso_cred);
                        if (dp != NULL) {
                                TAILQ_REMOVE(&clp->nfsc_deleg, dp, nfsdl_list);
                                TAILQ_INSERT_HEAD(&clp->nfsc_deleg, dp,
                                    nfsdl_list);
                                dp->nfsdl_timestamp = NFSD_MONOSEC + 120;
                                nfsstatsv1.cllocalopens++;
                        } else {
                                nfsstatsv1.clopens++;
                        }
                        LIST_INSERT_HEAD(&owp->nfsow_open, nop, nfso_list);
                        *opp = nop;
                        *nopp = NULL;
                        if (newonep != NULL)
                                *newonep = 1;
                } else {
                        *opp = op;
                }
        }
}

/*
 * Called to find/add a delegation to a client.
 */
APPLESTATIC int
nfscl_deleg(mount_t mp, struct nfsclclient *clp, u_int8_t *nfhp,
    int fhlen, struct ucred *cred, NFSPROC_T *p, struct nfscldeleg **dpp)
{
        struct nfscldeleg *dp = *dpp, *tdp;

        /*
         * First, if we have received a Read delegation for a file on a
         * read/write file system, just return it, because they aren't
         * useful, imho.
         */
        if (mp != NULL && dp != NULL && !NFSMNT_RDONLY(mp) &&
            (dp->nfsdl_flags & NFSCLDL_READ)) {
                (void) nfscl_trydelegreturn(dp, cred, VFSTONFS(mp), p);
                free(dp, M_NFSCLDELEG);
                *dpp = NULL;
                return (0);
        }

        /* Look for the correct deleg, based upon FH */
        NFSLOCKCLSTATE();
        tdp = nfscl_finddeleg(clp, nfhp, fhlen);
        if (tdp == NULL) {
                if (dp == NULL) {
                        NFSUNLOCKCLSTATE();
                        return (NFSERR_BADSTATEID);
                }
                *dpp = NULL;
                TAILQ_INSERT_HEAD(&clp->nfsc_deleg, dp, nfsdl_list);
                LIST_INSERT_HEAD(NFSCLDELEGHASH(clp, nfhp, fhlen), dp,
                    nfsdl_hash);
                dp->nfsdl_timestamp = NFSD_MONOSEC + 120;
                nfsstatsv1.cldelegates++;
                nfscl_delegcnt++;
        } else {
                /*
                 * Delegation already exists, what do we do if a new one??
                 */
                if (dp != NULL) {
                        printf("Deleg already exists!\n");
                        free(dp, M_NFSCLDELEG);
                        *dpp = NULL;
                } else {
                        *dpp = tdp;
                }
        }
        NFSUNLOCKCLSTATE();
        return (0);
}

/*
 * Find a delegation for this file handle. Return NULL upon failure.
 */
static struct nfscldeleg *
nfscl_finddeleg(struct nfsclclient *clp, u_int8_t *fhp, int fhlen)
{
        struct nfscldeleg *dp;

        LIST_FOREACH(dp, NFSCLDELEGHASH(clp, fhp, fhlen), nfsdl_hash) {
            if (dp->nfsdl_fhlen == fhlen &&
                !NFSBCMP(dp->nfsdl_fh, fhp, fhlen))
                break;
        }
        return (dp);
}

/*
 * Get a stateid for an I/O operation. First, look for an open and iff
 * found, return either a lockowner stateid or the open stateid.
 * If no Open is found, just return error and the special stateid of all zeros.
 */
APPLESTATIC int
nfscl_getstateid(vnode_t vp, u_int8_t *nfhp, int fhlen, u_int32_t mode,
    int fords, struct ucred *cred, NFSPROC_T *p, nfsv4stateid_t *stateidp,
    void **lckpp)
{
        struct nfsclclient *clp;
        struct nfsclowner *owp;
        struct nfsclopen *op = NULL, *top;
        struct nfscllockowner *lp;
        struct nfscldeleg *dp;
        struct nfsnode *np;
        struct nfsmount *nmp;
        u_int8_t own[NFSV4CL_LOCKNAMELEN];
        int error, done;

        *lckpp = NULL;
        /*
         * Initially, just set the special stateid of all zeros.
         * (Don't do this for a DS, since the special stateid can't be used.)
         */
        if (fords == 0) {
                stateidp->seqid = 0;
                stateidp->other[0] = 0;
                stateidp->other[1] = 0;
                stateidp->other[2] = 0;
        }
        if (vnode_vtype(vp) != VREG)
                return (EISDIR);
        np = VTONFS(vp);
        nmp = VFSTONFS(vnode_mount(vp));
        NFSLOCKCLSTATE();
        clp = nfscl_findcl(nmp);
        if (clp == NULL) {
                NFSUNLOCKCLSTATE();
                return (EACCES);
        }

        /*
         * Wait for recovery to complete.
         */
        while ((clp->nfsc_flags & NFSCLFLAGS_RECVRINPROG))
                (void) nfsmsleep(&clp->nfsc_flags, NFSCLSTATEMUTEXPTR,
                    PZERO, "nfsrecvr", NULL);

        /*
         * First, look for a delegation.
         */
        LIST_FOREACH(dp, NFSCLDELEGHASH(clp, nfhp, fhlen), nfsdl_hash) {
                if (dp->nfsdl_fhlen == fhlen &&
                    !NFSBCMP(nfhp, dp->nfsdl_fh, fhlen)) {
                        if (!(mode & NFSV4OPEN_ACCESSWRITE) ||
                            (dp->nfsdl_flags & NFSCLDL_WRITE)) {
                                stateidp->seqid = dp->nfsdl_stateid.seqid;
                                stateidp->other[0] = dp->nfsdl_stateid.other[0];
                                stateidp->other[1] = dp->nfsdl_stateid.other[1];
                                stateidp->other[2] = dp->nfsdl_stateid.other[2];
                                if (!(np->n_flag & NDELEGRECALL)) {
                                        TAILQ_REMOVE(&clp->nfsc_deleg, dp,
                                            nfsdl_list);
                                        TAILQ_INSERT_HEAD(&clp->nfsc_deleg, dp,
                                            nfsdl_list);
                                        dp->nfsdl_timestamp = NFSD_MONOSEC +
                                            120;
                                        dp->nfsdl_rwlock.nfslock_usecnt++;
                                        *lckpp = (void *)&dp->nfsdl_rwlock;
                                }
                                NFSUNLOCKCLSTATE();
                                return (0);
                        }
                        break;
                }
        }

        if (p != NULL) {
                /*
                 * If p != NULL, we want to search the parentage tree
                 * for a matching OpenOwner and use that.
                 */
                if (NFSHASONEOPENOWN(VFSTONFS(vnode_mount(vp))))
                        nfscl_filllockowner(NULL, own, F_POSIX);
                else
                        nfscl_filllockowner(p->td_proc, own, F_POSIX);
                lp = NULL;
                error = nfscl_getopen(&clp->nfsc_owner, nfhp, fhlen, own, own,
                    mode, &lp, &op);
                if (error == 0 && lp != NULL && fords == 0) {
                        /* Don't return a lock stateid for a DS. */
                        stateidp->seqid =
                            lp->nfsl_stateid.seqid;
                        stateidp->other[0] =
                            lp->nfsl_stateid.other[0];
                        stateidp->other[1] =
                            lp->nfsl_stateid.other[1];
                        stateidp->other[2] =
                            lp->nfsl_stateid.other[2];
                        NFSUNLOCKCLSTATE();
                        return (0);
                }
        }
        if (op == NULL) {
                /* If not found, just look for any OpenOwner that will work. */
                top = NULL;
                done = 0;
                owp = LIST_FIRST(&clp->nfsc_owner);
                while (!done && owp != NULL) {
                        LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                                if (op->nfso_fhlen == fhlen &&
                                    !NFSBCMP(op->nfso_fh, nfhp, fhlen)) {
                                        if (top == NULL && (op->nfso_mode &
                                            NFSV4OPEN_ACCESSWRITE) != 0 &&
                                            (mode & NFSV4OPEN_ACCESSREAD) != 0)
                                                top = op;
                                        if ((mode & op->nfso_mode) == mode) {
                                                done = 1;
                                                break;
                                        }
                                }
                        }
                        if (!done)
                                owp = LIST_NEXT(owp, nfsow_list);
                }
                if (!done) {
                        NFSCL_DEBUG(2, "openmode top=%p\n", top);
                        if (top == NULL || NFSHASOPENMODE(nmp)) {
                                NFSUNLOCKCLSTATE();
                                return (ENOENT);
                        } else
                                op = top;
                }
                /*
                 * For read aheads or write behinds, use the open cred.
                 * A read ahead or write behind is indicated by p == NULL.
                 */
                if (p == NULL)
                        newnfs_copycred(&op->nfso_cred, cred);
        }

        /*
         * No lock stateid, so return the open stateid.
         */
        stateidp->seqid = op->nfso_stateid.seqid;
        stateidp->other[0] = op->nfso_stateid.other[0];
        stateidp->other[1] = op->nfso_stateid.other[1];
        stateidp->other[2] = op->nfso_stateid.other[2];
        NFSUNLOCKCLSTATE();
        return (0);
}

/*
 * Search for a matching file, mode and, optionally, lockowner.
 */
static int
nfscl_getopen(struct nfsclownerhead *ohp, u_int8_t *nfhp, int fhlen,
    u_int8_t *openown, u_int8_t *lockown, u_int32_t mode,
    struct nfscllockowner **lpp, struct nfsclopen **opp)
{
        struct nfsclowner *owp;
        struct nfsclopen *op, *rop, *rop2;
        struct nfscllockowner *lp;
        int keep_looping;

        if (lpp != NULL)
                *lpp = NULL;
        /*
         * rop will be set to the open to be returned. There are three
         * variants of this, all for an open of the correct file:
         * 1 - A match of lockown.
         * 2 - A match of the openown, when no lockown match exists.
         * 3 - A match for any open, if no openown or lockown match exists.
         * Looking for #2 over #3 probably isn't necessary, but since
         * RFC3530 is vague w.r.t. the relationship between openowners and
         * lockowners, I think this is the safer way to go.
         */
        rop = NULL;
        rop2 = NULL;
        keep_looping = 1;
        /* Search the client list */
        owp = LIST_FIRST(ohp);
        while (owp != NULL && keep_looping != 0) {
                /* and look for the correct open */
                op = LIST_FIRST(&owp->nfsow_open);
                while (op != NULL && keep_looping != 0) {
                        if (op->nfso_fhlen == fhlen &&
                            !NFSBCMP(op->nfso_fh, nfhp, fhlen)
                            && (op->nfso_mode & mode) == mode) {
                                if (lpp != NULL) {
                                        /* Now look for a matching lockowner. */
                                        LIST_FOREACH(lp, &op->nfso_lock,
                                            nfsl_list) {
                                                if (!NFSBCMP(lp->nfsl_owner,
                                                    lockown,
                                                    NFSV4CL_LOCKNAMELEN)) {
                                                        *lpp = lp;
                                                        rop = op;
                                                        keep_looping = 0;
                                                        break;
                                                }
                                        }
                                }
                                if (rop == NULL && !NFSBCMP(owp->nfsow_owner,
                                    openown, NFSV4CL_LOCKNAMELEN)) {
                                        rop = op;
                                        if (lpp == NULL)
                                                keep_looping = 0;
                                }
                                if (rop2 == NULL)
                                        rop2 = op;
                        }
                        op = LIST_NEXT(op, nfso_list);
                }
                owp = LIST_NEXT(owp, nfsow_list);
        }
        if (rop == NULL)
                rop = rop2;
        if (rop == NULL)
                return (EBADF);
        *opp = rop;
        return (0);
}

/*
 * Release use of an open owner. Called when open operations are done
 * with the open owner.
 */
APPLESTATIC void
nfscl_ownerrelease(struct nfsmount *nmp, struct nfsclowner *owp,
    __unused int error, __unused int candelete, int unlocked)
{

        if (owp == NULL)
                return;
        NFSLOCKCLSTATE();
        if (unlocked == 0) {
                if (NFSHASONEOPENOWN(nmp))
                        nfsv4_relref(&owp->nfsow_rwlock);
                else
                        nfscl_lockunlock(&owp->nfsow_rwlock);
        }
        nfscl_clrelease(owp->nfsow_clp);
        NFSUNLOCKCLSTATE();
}

/*
 * Release use of an open structure under an open owner.
 */
APPLESTATIC void
nfscl_openrelease(struct nfsmount *nmp, struct nfsclopen *op, int error,
    int candelete)
{
        struct nfsclclient *clp;
        struct nfsclowner *owp;

        if (op == NULL)
                return;
        NFSLOCKCLSTATE();
        owp = op->nfso_own;
        if (NFSHASONEOPENOWN(nmp))
                nfsv4_relref(&owp->nfsow_rwlock);
        else
                nfscl_lockunlock(&owp->nfsow_rwlock);
        clp = owp->nfsow_clp;
        if (error && candelete && op->nfso_opencnt == 0)
                nfscl_freeopen(op, 0);
        nfscl_clrelease(clp);
        NFSUNLOCKCLSTATE();
}

/*
 * Called to get a clientid structure. It will optionally lock the
 * client data structures to do the SetClientId/SetClientId_confirm,
 * but will release that lock and return the clientid with a reference
 * count on it.
 * If the "cred" argument is NULL, a new clientid should not be created.
 * If the "p" argument is NULL, a SetClientID/SetClientIDConfirm cannot
 * be done.
 * The start_renewthread argument tells nfscl_getcl() to start a renew
 * thread if this creates a new clp.
 * It always clpp with a reference count on it, unless returning an error.
 */
APPLESTATIC int
nfscl_getcl(struct mount *mp, struct ucred *cred, NFSPROC_T *p,
    int start_renewthread, struct nfsclclient **clpp)
{
        struct nfsclclient *clp;
        struct nfsclclient *newclp = NULL;
        struct nfsmount *nmp;
        char uuid[HOSTUUIDLEN];
        int igotlock = 0, error, trystalecnt, clidinusedelay, i;
        u_int16_t idlen = 0;

        nmp = VFSTONFS(mp);
        if (cred != NULL) {
                getcredhostuuid(cred, uuid, sizeof uuid);
                idlen = strlen(uuid);
                if (idlen > 0)
                        idlen += sizeof (u_int64_t);
                else
                        idlen += sizeof (u_int64_t) + 16; /* 16 random bytes */
                newclp = malloc(
                    sizeof (struct nfsclclient) + idlen - 1, M_NFSCLCLIENT,
                    M_WAITOK | M_ZERO);
        }
        NFSLOCKCLSTATE();
        /*
         * If a forced dismount is already in progress, don't
         * allocate a new clientid and get out now. For the case where
         * clp != NULL, this is a harmless optimization.
         */
        if (NFSCL_FORCEDISM(mp)) {
                NFSUNLOCKCLSTATE();
                if (newclp != NULL)
                        free(newclp, M_NFSCLCLIENT);
                return (EBADF);
        }
        clp = nmp->nm_clp;
        if (clp == NULL) {
                if (newclp == NULL) {
                        NFSUNLOCKCLSTATE();
                        return (EACCES);
                }
                clp = newclp;
                clp->nfsc_idlen = idlen;
                LIST_INIT(&clp->nfsc_owner);
                TAILQ_INIT(&clp->nfsc_deleg);
                TAILQ_INIT(&clp->nfsc_layout);
                LIST_INIT(&clp->nfsc_devinfo);
                for (i = 0; i < NFSCLDELEGHASHSIZE; i++)
                        LIST_INIT(&clp->nfsc_deleghash[i]);
                for (i = 0; i < NFSCLLAYOUTHASHSIZE; i++)
                        LIST_INIT(&clp->nfsc_layouthash[i]);
                clp->nfsc_flags = NFSCLFLAGS_INITED;
                clp->nfsc_clientidrev = 1;
                clp->nfsc_cbident = nfscl_nextcbident();
                nfscl_fillclid(nmp->nm_clval, uuid, clp->nfsc_id,
                    clp->nfsc_idlen);
                LIST_INSERT_HEAD(&nfsclhead, clp, nfsc_list);
                nmp->nm_clp = clp;
                clp->nfsc_nmp = nmp;
                NFSUNLOCKCLSTATE();
                if (start_renewthread != 0)
                        nfscl_start_renewthread(clp);
        } else {
                NFSUNLOCKCLSTATE();
                if (newclp != NULL)
                        free(newclp, M_NFSCLCLIENT);
        }
        NFSLOCKCLSTATE();
        while ((clp->nfsc_flags & NFSCLFLAGS_HASCLIENTID) == 0 && !igotlock &&
            !NFSCL_FORCEDISM(mp))
                igotlock = nfsv4_lock(&clp->nfsc_lock, 1, NULL,
                    NFSCLSTATEMUTEXPTR, mp);
        if (igotlock == 0) {
                /*
                 * Call nfsv4_lock() with "iwantlock == 0" so that it will
                 * wait for a pending exclusive lock request.  This gives the
                 * exclusive lock request priority over this shared lock
                 * request.
                 * An exclusive lock on nfsc_lock is used mainly for server
                 * crash recoveries.
                 */
                nfsv4_lock(&clp->nfsc_lock, 0, NULL, NFSCLSTATEMUTEXPTR, mp);
                nfsv4_getref(&clp->nfsc_lock, NULL, NFSCLSTATEMUTEXPTR, mp);
        }
        if (igotlock == 0 && NFSCL_FORCEDISM(mp)) {
                /*
                 * Both nfsv4_lock() and nfsv4_getref() know to check
                 * for NFSCL_FORCEDISM() and return without sleeping to
                 * wait for the exclusive lock to be released, since it
                 * might be held by nfscl_umount() and we need to get out
                 * now for that case and not wait until nfscl_umount()
                 * releases it.
                 */
                NFSUNLOCKCLSTATE();
                return (EBADF);
        }
        NFSUNLOCKCLSTATE();

        /*
         * If it needs a clientid, do the setclientid now.
         */
        if ((clp->nfsc_flags & NFSCLFLAGS_HASCLIENTID) == 0) {
                if (!igotlock)
                        panic("nfscl_clget");
                if (p == NULL || cred == NULL) {
                        NFSLOCKCLSTATE();
                        nfsv4_unlock(&clp->nfsc_lock, 0);
                        NFSUNLOCKCLSTATE();
                        return (EACCES);
                }
                /*
                 * If RFC3530 Sec. 14.2.33 is taken literally,
                 * NFSERR_CLIDINUSE will be returned persistently for the
                 * case where a new mount of the same file system is using
                 * a different principal. In practice, NFSERR_CLIDINUSE is
                 * only returned when there is outstanding unexpired state
                 * on the clientid. As such, try for twice the lease
                 * interval, if we know what that is. Otherwise, make a
                 * wild ass guess.
                 * The case of returning NFSERR_STALECLIENTID is far less
                 * likely, but might occur if there is a significant delay
                 * between doing the SetClientID and SetClientIDConfirm Ops,
                 * such that the server throws away the clientid before
                 * receiving the SetClientIDConfirm.
                 */
                if (clp->nfsc_renew > 0)
                        clidinusedelay = NFSCL_LEASE(clp->nfsc_renew) * 2;
                else
                        clidinusedelay = 120;
                trystalecnt = 3;
                do {
                        error = nfsrpc_setclient(nmp, clp, 0, cred, p);
                        if (error == NFSERR_STALECLIENTID ||
                            error == NFSERR_STALEDONTRECOVER ||
                            error == NFSERR_BADSESSION ||
                            error == NFSERR_CLIDINUSE) {
                                (void) nfs_catnap(PZERO, error, "nfs_setcl");
                        }
                } while (((error == NFSERR_STALECLIENTID ||
                     error == NFSERR_BADSESSION ||
                     error == NFSERR_STALEDONTRECOVER) && --trystalecnt > 0) ||
                    (error == NFSERR_CLIDINUSE && --clidinusedelay > 0));
                if (error) {
                        NFSLOCKCLSTATE();
                        nfsv4_unlock(&clp->nfsc_lock, 0);
                        NFSUNLOCKCLSTATE();
                        return (error);
                }
                clp->nfsc_flags |= NFSCLFLAGS_HASCLIENTID;
        }
        if (igotlock) {
                NFSLOCKCLSTATE();
                nfsv4_unlock(&clp->nfsc_lock, 1);
                NFSUNLOCKCLSTATE();
        }

        *clpp = clp;
        return (0);
}

/*
 * Get a reference to a clientid and return it, if valid.
 */
APPLESTATIC struct nfsclclient *
nfscl_findcl(struct nfsmount *nmp)
{
        struct nfsclclient *clp;

        clp = nmp->nm_clp;
        if (clp == NULL || !(clp->nfsc_flags & NFSCLFLAGS_HASCLIENTID))
                return (NULL);
        return (clp);
}

/*
 * Release the clientid structure. It may be locked or reference counted.
 */
static void
nfscl_clrelease(struct nfsclclient *clp)
{

        if (clp->nfsc_lock.nfslock_lock & NFSV4LOCK_LOCK)
                nfsv4_unlock(&clp->nfsc_lock, 0);
        else
                nfsv4_relref(&clp->nfsc_lock);
}

/*
 * External call for nfscl_clrelease.
 */
APPLESTATIC void
nfscl_clientrelease(struct nfsclclient *clp)
{

        NFSLOCKCLSTATE();
        if (clp->nfsc_lock.nfslock_lock & NFSV4LOCK_LOCK)
                nfsv4_unlock(&clp->nfsc_lock, 0);
        else
                nfsv4_relref(&clp->nfsc_lock);
        NFSUNLOCKCLSTATE();
}

/*
 * Called when wanting to lock a byte region.
 */
APPLESTATIC int
nfscl_getbytelock(vnode_t vp, u_int64_t off, u_int64_t len,
    short type, struct ucred *cred, NFSPROC_T *p, struct nfsclclient *rclp,
    int recovery, void *id, int flags, u_int8_t *rownp, u_int8_t *ropenownp,
    struct nfscllockowner **lpp, int *newonep, int *donelocallyp)
{
        struct nfscllockowner *lp;
        struct nfsclopen *op;
        struct nfsclclient *clp;
        struct nfscllockowner *nlp;
        struct nfscllock *nlop, *otherlop;
        struct nfscldeleg *dp = NULL, *ldp = NULL;
        struct nfscllockownerhead *lhp = NULL;
        struct nfsnode *np;
        u_int8_t own[NFSV4CL_LOCKNAMELEN], *ownp, openown[NFSV4CL_LOCKNAMELEN];
        u_int8_t *openownp;
        int error = 0, ret, donelocally = 0;
        u_int32_t mode;

        /* For Lock Ops, the open mode doesn't matter, so use 0 to match any. */
        mode = 0;
        np = VTONFS(vp);
        *lpp = NULL;
        lp = NULL;
        *newonep = 0;
        *donelocallyp = 0;

        /*
         * Might need these, so MALLOC them now, to
         * avoid a tsleep() in MALLOC later.
         */
        nlp = malloc(
            sizeof (struct nfscllockowner), M_NFSCLLOCKOWNER, M_WAITOK);
        otherlop = malloc(
            sizeof (struct nfscllock), M_NFSCLLOCK, M_WAITOK);
        nlop = malloc(
            sizeof (struct nfscllock), M_NFSCLLOCK, M_WAITOK);
        nlop->nfslo_type = type;
        nlop->nfslo_first = off;
        if (len == NFS64BITSSET) {
                nlop->nfslo_end = NFS64BITSSET;
        } else {
                nlop->nfslo_end = off + len;
                if (nlop->nfslo_end <= nlop->nfslo_first)
                        error = NFSERR_INVAL;
        }

        if (!error) {
                if (recovery)
                        clp = rclp;
                else
                        error = nfscl_getcl(vnode_mount(vp), cred, p, 1, &clp);
        }
        if (error) {
                free(nlp, M_NFSCLLOCKOWNER);
                free(otherlop, M_NFSCLLOCK);
                free(nlop, M_NFSCLLOCK);
                return (error);
        }

        op = NULL;
        if (recovery) {
                ownp = rownp;
                openownp = ropenownp;
        } else {
                nfscl_filllockowner(id, own, flags);
                ownp = own;
                if (NFSHASONEOPENOWN(VFSTONFS(vnode_mount(vp))))
                        nfscl_filllockowner(NULL, openown, F_POSIX);
                else
                        nfscl_filllockowner(p->td_proc, openown, F_POSIX);
                openownp = openown;
        }
        if (!recovery) {
                NFSLOCKCLSTATE();
                /*
                 * First, search for a delegation. If one exists for this file,
                 * the lock can be done locally against it, so long as there
                 * isn't a local lock conflict.
                 */
                ldp = dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh,
                    np->n_fhp->nfh_len);
                /* Just sanity check for correct type of delegation */
                if (dp != NULL && ((dp->nfsdl_flags &
                    (NFSCLDL_RECALL | NFSCLDL_DELEGRET)) != 0 ||
                     (type == F_WRLCK &&
                      (dp->nfsdl_flags & NFSCLDL_WRITE) == 0)))
                        dp = NULL;
        }
        if (dp != NULL) {
                /* Now, find an open and maybe a lockowner. */
                ret = nfscl_getopen(&dp->nfsdl_owner, np->n_fhp->nfh_fh,
                    np->n_fhp->nfh_len, openownp, ownp, mode, NULL, &op);
                if (ret)
                        ret = nfscl_getopen(&clp->nfsc_owner,
                            np->n_fhp->nfh_fh, np->n_fhp->nfh_len, openownp,
                            ownp, mode, NULL, &op);
                if (!ret) {
                        lhp = &dp->nfsdl_lock;
                        TAILQ_REMOVE(&clp->nfsc_deleg, dp, nfsdl_list);
                        TAILQ_INSERT_HEAD(&clp->nfsc_deleg, dp, nfsdl_list);
                        dp->nfsdl_timestamp = NFSD_MONOSEC + 120;
                        donelocally = 1;
                } else {
                        dp = NULL;
                }
        }
        if (!donelocally) {
                /*
                 * Get the related Open and maybe lockowner.
                 */
                error = nfscl_getopen(&clp->nfsc_owner,
                    np->n_fhp->nfh_fh, np->n_fhp->nfh_len, openownp,
                    ownp, mode, &lp, &op);
                if (!error)
                        lhp = &op->nfso_lock;
        }
        if (!error && !recovery)
                error = nfscl_localconflict(clp, np->n_fhp->nfh_fh,
                    np->n_fhp->nfh_len, nlop, ownp, ldp, NULL);
        if (error) {
                if (!recovery) {
                        nfscl_clrelease(clp);
                        NFSUNLOCKCLSTATE();
                }
                free(nlp, M_NFSCLLOCKOWNER);
                free(otherlop, M_NFSCLLOCK);
                free(nlop, M_NFSCLLOCK);
                return (error);
        }

        /*
         * Ok, see if a lockowner exists and create one, as required.
         */
        if (lp == NULL)
                LIST_FOREACH(lp, lhp, nfsl_list) {
                        if (!NFSBCMP(lp->nfsl_owner, ownp, NFSV4CL_LOCKNAMELEN))
                                break;
                }
        if (lp == NULL) {
                NFSBCOPY(ownp, nlp->nfsl_owner, NFSV4CL_LOCKNAMELEN);
                if (recovery)
                        NFSBCOPY(ropenownp, nlp->nfsl_openowner,
                            NFSV4CL_LOCKNAMELEN);
                else
                        NFSBCOPY(op->nfso_own->nfsow_owner, nlp->nfsl_openowner,
                            NFSV4CL_LOCKNAMELEN);
                nlp->nfsl_seqid = 0;
                nlp->nfsl_lockflags = flags;
                nlp->nfsl_inprog = NULL;
                nfscl_lockinit(&nlp->nfsl_rwlock);
                LIST_INIT(&nlp->nfsl_lock);
                if (donelocally) {
                        nlp->nfsl_open = NULL;
                        nfsstatsv1.cllocallockowners++;
                } else {
                        nlp->nfsl_open = op;
                        nfsstatsv1.cllockowners++;
                }
                LIST_INSERT_HEAD(lhp, nlp, nfsl_list);
                lp = nlp;
                nlp = NULL;
                *newonep = 1;
        }

        /*
         * Now, update the byte ranges for locks.
         */
        ret = nfscl_updatelock(lp, &nlop, &otherlop, donelocally);
        if (!ret)
                donelocally = 1;
        if (donelocally) {
                *donelocallyp = 1;
                if (!recovery)
                        nfscl_clrelease(clp);
        } else {
                /*
                 * Serial modifications on the lock owner for multiple threads
                 * for the same process using a read/write lock.
                 */
                if (!recovery)
                        nfscl_lockexcl(&lp->nfsl_rwlock, NFSCLSTATEMUTEXPTR);
        }
        if (!recovery)
                NFSUNLOCKCLSTATE();

        if (nlp)
                free(nlp, M_NFSCLLOCKOWNER);
        if (nlop)
                free(nlop, M_NFSCLLOCK);
        if (otherlop)
                free(otherlop, M_NFSCLLOCK);

        *lpp = lp;
        return (0);
}

/*
 * Called to unlock a byte range, for LockU.
 */
APPLESTATIC int
nfscl_relbytelock(vnode_t vp, u_int64_t off, u_int64_t len,
    __unused struct ucred *cred, NFSPROC_T *p, int callcnt,
    struct nfsclclient *clp, void *id, int flags,
    struct nfscllockowner **lpp, int *dorpcp)
{
        struct nfscllockowner *lp;
        struct nfsclowner *owp;
        struct nfsclopen *op;
        struct nfscllock *nlop, *other_lop = NULL;
        struct nfscldeleg *dp;
        struct nfsnode *np;
        u_int8_t own[NFSV4CL_LOCKNAMELEN];
        int ret = 0, fnd;

        np = VTONFS(vp);
        *lpp = NULL;
        *dorpcp = 0;

        /*
         * Might need these, so MALLOC them now, to
         * avoid a tsleep() in MALLOC later.
         */
        nlop = malloc(
            sizeof (struct nfscllock), M_NFSCLLOCK, M_WAITOK);
        nlop->nfslo_type = F_UNLCK;
        nlop->nfslo_first = off;
        if (len == NFS64BITSSET) {
                nlop->nfslo_end = NFS64BITSSET;
        } else {
                nlop->nfslo_end = off + len;
                if (nlop->nfslo_end <= nlop->nfslo_first) {
                        free(nlop, M_NFSCLLOCK);
                        return (NFSERR_INVAL);
                }
        }
        if (callcnt == 0) {
                other_lop = malloc(
                    sizeof (struct nfscllock), M_NFSCLLOCK, M_WAITOK);
                *other_lop = *nlop;
        }
        nfscl_filllockowner(id, own, flags);
        dp = NULL;
        NFSLOCKCLSTATE();
        if (callcnt == 0)
                dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh,
                    np->n_fhp->nfh_len);

        /*
         * First, unlock any local regions on a delegation.
         */
        if (dp != NULL) {
                /* Look for this lockowner. */
                LIST_FOREACH(lp, &dp->nfsdl_lock, nfsl_list) {
                        if (!NFSBCMP(lp->nfsl_owner, own,
                            NFSV4CL_LOCKNAMELEN))
                                break;
                }
                if (lp != NULL)
                        /* Use other_lop, so nlop is still available */
                        (void)nfscl_updatelock(lp, &other_lop, NULL, 1);
        }

        /*
         * Now, find a matching open/lockowner that hasn't already been done,
         * as marked by nfsl_inprog.
         */
        lp = NULL;
        fnd = 0;
        LIST_FOREACH(owp, &clp->nfsc_owner, nfsow_list) {
            LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                if (op->nfso_fhlen == np->n_fhp->nfh_len &&
                    !NFSBCMP(op->nfso_fh, np->n_fhp->nfh_fh, op->nfso_fhlen)) {
                    LIST_FOREACH(lp, &op->nfso_lock, nfsl_list) {
                        if (lp->nfsl_inprog == NULL &&
                            !NFSBCMP(lp->nfsl_owner, own,
                             NFSV4CL_LOCKNAMELEN)) {
                                fnd = 1;
                                break;
                        }
                    }
                    if (fnd)
                        break;
                }
            }
            if (fnd)
                break;
        }

        if (lp != NULL) {
                ret = nfscl_updatelock(lp, &nlop, NULL, 0);
                if (ret)
                        *dorpcp = 1;
                /*
                 * Serial modifications on the lock owner for multiple
                 * threads for the same process using a read/write lock.
                 */
                lp->nfsl_inprog = p;
                nfscl_lockexcl(&lp->nfsl_rwlock, NFSCLSTATEMUTEXPTR);
                *lpp = lp;
        }
        NFSUNLOCKCLSTATE();
        if (nlop)
                free(nlop, M_NFSCLLOCK);
        if (other_lop)
                free(other_lop, M_NFSCLLOCK);
        return (0);
}

/*
 * Release all lockowners marked in progess for this process and file.
 */
APPLESTATIC void
nfscl_releasealllocks(struct nfsclclient *clp, vnode_t vp, NFSPROC_T *p,
    void *id, int flags)
{
        struct nfsclowner *owp;
        struct nfsclopen *op;
        struct nfscllockowner *lp;
        struct nfsnode *np;
        u_int8_t own[NFSV4CL_LOCKNAMELEN];

        np = VTONFS(vp);
        nfscl_filllockowner(id, own, flags);
        NFSLOCKCLSTATE();
        LIST_FOREACH(owp, &clp->nfsc_owner, nfsow_list) {
            LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                if (op->nfso_fhlen == np->n_fhp->nfh_len &&
                    !NFSBCMP(op->nfso_fh, np->n_fhp->nfh_fh, op->nfso_fhlen)) {
                    LIST_FOREACH(lp, &op->nfso_lock, nfsl_list) {
                        if (lp->nfsl_inprog == p &&
                            !NFSBCMP(lp->nfsl_owner, own,
                            NFSV4CL_LOCKNAMELEN)) {
                            lp->nfsl_inprog = NULL;
                            nfscl_lockunlock(&lp->nfsl_rwlock);
                        }
                    }
                }
            }
        }
        nfscl_clrelease(clp);
        NFSUNLOCKCLSTATE();
}

/*
 * Called to find out if any bytes within the byte range specified are
 * write locked by the calling process. Used to determine if flushing
 * is required before a LockU.
 * If in doubt, return 1, so the flush will occur.
 */
APPLESTATIC int
nfscl_checkwritelocked(vnode_t vp, struct flock *fl,
    struct ucred *cred, NFSPROC_T *p, void *id, int flags)
{
        struct nfsclowner *owp;
        struct nfscllockowner *lp;
        struct nfsclopen *op;
        struct nfsclclient *clp;
        struct nfscllock *lop;
        struct nfscldeleg *dp;
        struct nfsnode *np;
        u_int64_t off, end;
        u_int8_t own[NFSV4CL_LOCKNAMELEN];
        int error = 0;

        np = VTONFS(vp);
        switch (fl->l_whence) {
        case SEEK_SET:
        case SEEK_CUR:
                /*
                 * Caller is responsible for adding any necessary offset
                 * when SEEK_CUR is used.
                 */
                off = fl->l_start;
                break;
        case SEEK_END:
                off = np->n_size + fl->l_start;
                break;
        default:
                return (1);
        }
        if (fl->l_len != 0) {
                end = off + fl->l_len;
                if (end < off)
                        return (1);
        } else {
                end = NFS64BITSSET;
        }

        error = nfscl_getcl(vnode_mount(vp), cred, p, 1, &clp);
        if (error)
                return (1);
        nfscl_filllockowner(id, own, flags);
        NFSLOCKCLSTATE();

        /*
         * First check the delegation locks.
         */
        dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh, np->n_fhp->nfh_len);
        if (dp != NULL) {
                LIST_FOREACH(lp, &dp->nfsdl_lock, nfsl_list) {
                        if (!NFSBCMP(lp->nfsl_owner, own,
                            NFSV4CL_LOCKNAMELEN))
                                break;
                }
                if (lp != NULL) {
                        LIST_FOREACH(lop, &lp->nfsl_lock, nfslo_list) {
                                if (lop->nfslo_first >= end)
                                        break;
                                if (lop->nfslo_end <= off)
                                        continue;
                                if (lop->nfslo_type == F_WRLCK) {
                                        nfscl_clrelease(clp);
                                        NFSUNLOCKCLSTATE();
                                        return (1);
                                }
                        }
                }
        }

        /*
         * Now, check state against the server.
         */
        LIST_FOREACH(owp, &clp->nfsc_owner, nfsow_list) {
            LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                if (op->nfso_fhlen == np->n_fhp->nfh_len &&
                    !NFSBCMP(op->nfso_fh, np->n_fhp->nfh_fh, op->nfso_fhlen)) {
                    LIST_FOREACH(lp, &op->nfso_lock, nfsl_list) {
                        if (!NFSBCMP(lp->nfsl_owner, own,
                            NFSV4CL_LOCKNAMELEN))
                            break;
                    }
                    if (lp != NULL) {
                        LIST_FOREACH(lop, &lp->nfsl_lock, nfslo_list) {
                            if (lop->nfslo_first >= end)
                                break;
                            if (lop->nfslo_end <= off)
                                continue;
                            if (lop->nfslo_type == F_WRLCK) {
                                nfscl_clrelease(clp);
                                NFSUNLOCKCLSTATE();
                                return (1);
                            }
                        }
                    }
                }
            }
        }
        nfscl_clrelease(clp);
        NFSUNLOCKCLSTATE();
        return (0);
}

/*
 * Release a byte range lock owner structure.
 */
APPLESTATIC void
nfscl_lockrelease(struct nfscllockowner *lp, int error, int candelete)
{
        struct nfsclclient *clp;

        if (lp == NULL)
                return;
        NFSLOCKCLSTATE();
        clp = lp->nfsl_open->nfso_own->nfsow_clp;
        if (error != 0 && candelete &&
            (lp->nfsl_rwlock.nfslock_lock & NFSV4LOCK_WANTED) == 0)
                nfscl_freelockowner(lp, 0);
        else
                nfscl_lockunlock(&lp->nfsl_rwlock);
        nfscl_clrelease(clp);
        NFSUNLOCKCLSTATE();
}

/*
 * Free up an open structure and any associated byte range lock structures.
 */
APPLESTATIC void
nfscl_freeopen(struct nfsclopen *op, int local)
{

        LIST_REMOVE(op, nfso_list);
        nfscl_freealllocks(&op->nfso_lock, local);
        free(op, M_NFSCLOPEN);
        if (local)
                nfsstatsv1.cllocalopens--;
        else
                nfsstatsv1.clopens--;
}

/*
 * Free up all lock owners and associated locks.
 */
static void
nfscl_freealllocks(struct nfscllockownerhead *lhp, int local)
{
        struct nfscllockowner *lp, *nlp;

        LIST_FOREACH_SAFE(lp, lhp, nfsl_list, nlp) {
                if ((lp->nfsl_rwlock.nfslock_lock & NFSV4LOCK_WANTED))
                        panic("nfscllckw");
                nfscl_freelockowner(lp, local);
        }
}

/*
 * Called for an Open when NFSERR_EXPIRED is received from the server.
 * If there are no byte range locks nor a Share Deny lost, try to do a
 * fresh Open. Otherwise, free the open.
 */
static int
nfscl_expireopen(struct nfsclclient *clp, struct nfsclopen *op,
    struct nfsmount *nmp, struct ucred *cred, NFSPROC_T *p)
{
        struct nfscllockowner *lp;
        struct nfscldeleg *dp;
        int mustdelete = 0, error;

        /*
         * Look for any byte range lock(s).
         */
        LIST_FOREACH(lp, &op->nfso_lock, nfsl_list) {
                if (!LIST_EMPTY(&lp->nfsl_lock)) {
                        mustdelete = 1;
                        break;
                }
        }

        /*
         * If no byte range lock(s) nor a Share deny, try to re-open.
         */
        if (!mustdelete && (op->nfso_mode & NFSLCK_DENYBITS) == 0) {
                newnfs_copycred(&op->nfso_cred, cred);
                dp = NULL;
                error = nfsrpc_reopen(nmp, op->nfso_fh,
                    op->nfso_fhlen, op->nfso_mode, op, &dp, cred, p);
                if (error) {
                        mustdelete = 1;
                        if (dp != NULL) {
                                free(dp, M_NFSCLDELEG);
                                dp = NULL;
                        }
                }
                if (dp != NULL)
                        nfscl_deleg(nmp->nm_mountp, clp, op->nfso_fh,
                            op->nfso_fhlen, cred, p, &dp);
        }

        /*
         * If a byte range lock or Share deny or couldn't re-open, free it.
         */
        if (mustdelete)
                nfscl_freeopen(op, 0);
        return (mustdelete);
}

/*
 * Free up an open owner structure.
 */
static void
nfscl_freeopenowner(struct nfsclowner *owp, int local)
{

        LIST_REMOVE(owp, nfsow_list);
        free(owp, M_NFSCLOWNER);
        if (local)
                nfsstatsv1.cllocalopenowners--;
        else
                nfsstatsv1.clopenowners--;
}

/*
 * Free up a byte range lock owner structure.
 */
APPLESTATIC void
nfscl_freelockowner(struct nfscllockowner *lp, int local)
{
        struct nfscllock *lop, *nlop;

        LIST_REMOVE(lp, nfsl_list);
        LIST_FOREACH_SAFE(lop, &lp->nfsl_lock, nfslo_list, nlop) {
                nfscl_freelock(lop, local);
        }
        free(lp, M_NFSCLLOCKOWNER);
        if (local)
                nfsstatsv1.cllocallockowners--;
        else
                nfsstatsv1.cllockowners--;
}

/*
 * Free up a byte range lock structure.
 */
APPLESTATIC void
nfscl_freelock(struct nfscllock *lop, int local)
{

        LIST_REMOVE(lop, nfslo_list);
        free(lop, M_NFSCLLOCK);
        if (local)
                nfsstatsv1.cllocallocks--;
        else
                nfsstatsv1.cllocks--;
}

/*
 * Clean out the state related to a delegation.
 */
static void
nfscl_cleandeleg(struct nfscldeleg *dp)
{
        struct nfsclowner *owp, *nowp;
        struct nfsclopen *op;

        LIST_FOREACH_SAFE(owp, &dp->nfsdl_owner, nfsow_list, nowp) {
                op = LIST_FIRST(&owp->nfsow_open);
                if (op != NULL) {
                        if (LIST_NEXT(op, nfso_list) != NULL)
                                panic("nfscleandel");
                        nfscl_freeopen(op, 1);
                }
                nfscl_freeopenowner(owp, 1);
        }
        nfscl_freealllocks(&dp->nfsdl_lock, 1);
}

/*
 * Free a delegation.
 */
static void
nfscl_freedeleg(struct nfscldeleghead *hdp, struct nfscldeleg *dp)
{

        TAILQ_REMOVE(hdp, dp, nfsdl_list);
        LIST_REMOVE(dp, nfsdl_hash);
        free(dp, M_NFSCLDELEG);
        nfsstatsv1.cldelegates--;
        nfscl_delegcnt--;
}

/*
 * Free up all state related to this client structure.
 */
static void
nfscl_cleanclient(struct nfsclclient *clp)
{
        struct nfsclowner *owp, *nowp;
        struct nfsclopen *op, *nop;
        struct nfscllayout *lyp, *nlyp;
        struct nfscldevinfo *dip, *ndip;

        TAILQ_FOREACH_SAFE(lyp, &clp->nfsc_layout, nfsly_list, nlyp)
                nfscl_freelayout(lyp);

        LIST_FOREACH_SAFE(dip, &clp->nfsc_devinfo, nfsdi_list, ndip)
                nfscl_freedevinfo(dip);

        /* Now, all the OpenOwners, etc. */
        LIST_FOREACH_SAFE(owp, &clp->nfsc_owner, nfsow_list, nowp) {
                LIST_FOREACH_SAFE(op, &owp->nfsow_open, nfso_list, nop) {
                        nfscl_freeopen(op, 0);
                }
                nfscl_freeopenowner(owp, 0);
        }
}

/*
 * Called when an NFSERR_EXPIRED is received from the server.
 */
static void
nfscl_expireclient(struct nfsclclient *clp, struct nfsmount *nmp,
    struct ucred *cred, NFSPROC_T *p)
{
        struct nfsclowner *owp, *nowp, *towp;
        struct nfsclopen *op, *nop, *top;
        struct nfscldeleg *dp, *ndp;
        int ret, printed = 0;

        /*
         * First, merge locally issued Opens into the list for the server.
         */
        dp = TAILQ_FIRST(&clp->nfsc_deleg);
        while (dp != NULL) {
            ndp = TAILQ_NEXT(dp, nfsdl_list);
            owp = LIST_FIRST(&dp->nfsdl_owner);
            while (owp != NULL) {
                nowp = LIST_NEXT(owp, nfsow_list);
                op = LIST_FIRST(&owp->nfsow_open);
                if (op != NULL) {
                    if (LIST_NEXT(op, nfso_list) != NULL)
                        panic("nfsclexp");
                    LIST_FOREACH(towp, &clp->nfsc_owner, nfsow_list) {
                        if (!NFSBCMP(towp->nfsow_owner, owp->nfsow_owner,
                            NFSV4CL_LOCKNAMELEN))
                            break;
                    }
                    if (towp != NULL) {
                        /* Merge opens in */
                        LIST_FOREACH(top, &towp->nfsow_open, nfso_list) {
                            if (top->nfso_fhlen == op->nfso_fhlen &&
                                !NFSBCMP(top->nfso_fh, op->nfso_fh,
                                 op->nfso_fhlen)) {
                                top->nfso_mode |= op->nfso_mode;
                                top->nfso_opencnt += op->nfso_opencnt;
                                break;
                            }
                        }
                        if (top == NULL) {
                            /* Just add the open to the owner list */
                            LIST_REMOVE(op, nfso_list);
                            op->nfso_own = towp;
                            LIST_INSERT_HEAD(&towp->nfsow_open, op, nfso_list);
                            nfsstatsv1.cllocalopens--;
                            nfsstatsv1.clopens++;
                        }
                    } else {
                        /* Just add the openowner to the client list */
                        LIST_REMOVE(owp, nfsow_list);
                        owp->nfsow_clp = clp;
                        LIST_INSERT_HEAD(&clp->nfsc_owner, owp, nfsow_list);
                        nfsstatsv1.cllocalopenowners--;
                        nfsstatsv1.clopenowners++;
                        nfsstatsv1.cllocalopens--;
                        nfsstatsv1.clopens++;
                    }
                }
                owp = nowp;
            }
            if (!printed && !LIST_EMPTY(&dp->nfsdl_lock)) {
                printed = 1;
                printf("nfsv4 expired locks lost\n");
            }
            nfscl_cleandeleg(dp);
            nfscl_freedeleg(&clp->nfsc_deleg, dp);
            dp = ndp;
        }
        if (!TAILQ_EMPTY(&clp->nfsc_deleg))
            panic("nfsclexp");

        /*
         * Now, try and reopen against the server.
         */
        LIST_FOREACH_SAFE(owp, &clp->nfsc_owner, nfsow_list, nowp) {
                owp->nfsow_seqid = 0;
                LIST_FOREACH_SAFE(op, &owp->nfsow_open, nfso_list, nop) {
                        ret = nfscl_expireopen(clp, op, nmp, cred, p);
                        if (ret && !printed) {
                                printed = 1;
                                printf("nfsv4 expired locks lost\n");
                        }
                }
                if (LIST_EMPTY(&owp->nfsow_open))
                        nfscl_freeopenowner(owp, 0);
        }
}

/*
 * This function must be called after the process represented by "own" has
 * exited. Must be called with CLSTATE lock held.
 */
static void
nfscl_cleanup_common(struct nfsclclient *clp, u_int8_t *own)
{
        struct nfsclowner *owp, *nowp;
        struct nfscllockowner *lp, *nlp;
        struct nfscldeleg *dp;

        /* First, get rid of local locks on delegations. */
        TAILQ_FOREACH(dp, &clp->nfsc_deleg, nfsdl_list) {
                LIST_FOREACH_SAFE(lp, &dp->nfsdl_lock, nfsl_list, nlp) {
                    if (!NFSBCMP(lp->nfsl_owner, own, NFSV4CL_LOCKNAMELEN)) {
                        if ((lp->nfsl_rwlock.nfslock_lock & NFSV4LOCK_WANTED))
                            panic("nfscllckw");
                        nfscl_freelockowner(lp, 1);
                    }
                }
        }
        owp = LIST_FIRST(&clp->nfsc_owner);
        while (owp != NULL) {
                nowp = LIST_NEXT(owp, nfsow_list);
                if (!NFSBCMP(owp->nfsow_owner, own,
                    NFSV4CL_LOCKNAMELEN)) {
                        /*
                         * If there are children that haven't closed the
                         * file descriptors yet, the opens will still be
                         * here. For that case, let the renew thread clear
                         * out the OpenOwner later.
                         */
                        if (LIST_EMPTY(&owp->nfsow_open))
                                nfscl_freeopenowner(owp, 0);
                        else
                                owp->nfsow_defunct = 1;
                }
                owp = nowp;
        }
}

/*
 * Find open/lock owners for processes that have exited.
 */
static void
nfscl_cleanupkext(struct nfsclclient *clp, struct nfscllockownerfhhead *lhp)
{
        struct nfsclowner *owp, *nowp;
        struct nfsclopen *op;
        struct nfscllockowner *lp, *nlp;
        struct nfscldeleg *dp;

        NFSPROCLISTLOCK();
        NFSLOCKCLSTATE();
        LIST_FOREACH_SAFE(owp, &clp->nfsc_owner, nfsow_list, nowp) {
                LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                        LIST_FOREACH_SAFE(lp, &op->nfso_lock, nfsl_list, nlp) {
                                if (LIST_EMPTY(&lp->nfsl_lock))
                                        nfscl_emptylockowner(lp, lhp);
                        }
                }
                if (nfscl_procdoesntexist(owp->nfsow_owner))
                        nfscl_cleanup_common(clp, owp->nfsow_owner);
        }

        /*
         * For the single open_owner case, these lock owners need to be
         * checked to see if they still exist separately.
         * This is because nfscl_procdoesntexist() never returns true for
         * the single open_owner so that the above doesn't ever call
         * nfscl_cleanup_common().
         */
        TAILQ_FOREACH(dp, &clp->nfsc_deleg, nfsdl_list) {
                LIST_FOREACH_SAFE(lp, &dp->nfsdl_lock, nfsl_list, nlp) {
                        if (nfscl_procdoesntexist(lp->nfsl_owner))
                                nfscl_cleanup_common(clp, lp->nfsl_owner);
                }
        }
        NFSUNLOCKCLSTATE();
        NFSPROCLISTUNLOCK();
}

/*
 * Take the empty lock owner and move it to the local lhp list if the
 * associated process no longer exists.
 */
static void
nfscl_emptylockowner(struct nfscllockowner *lp,
    struct nfscllockownerfhhead *lhp)
{
        struct nfscllockownerfh *lfhp, *mylfhp;
        struct nfscllockowner *nlp;
        int fnd_it;

        /* If not a Posix lock owner, just return. */
        if ((lp->nfsl_lockflags & F_POSIX) == 0)
                return;

        fnd_it = 0;
        mylfhp = NULL;
        /*
         * First, search to see if this lock owner is already in the list.
         * If it is, then the associated process no longer exists.
         */
        SLIST_FOREACH(lfhp, lhp, nfslfh_list) {
                if (lfhp->nfslfh_len == lp->nfsl_open->nfso_fhlen &&
                    !NFSBCMP(lfhp->nfslfh_fh, lp->nfsl_open->nfso_fh,
                    lfhp->nfslfh_len))
                        mylfhp = lfhp;
                LIST_FOREACH(nlp, &lfhp->nfslfh_lock, nfsl_list)
                        if (!NFSBCMP(nlp->nfsl_owner, lp->nfsl_owner,
                            NFSV4CL_LOCKNAMELEN))
                                fnd_it = 1;
        }
        /* If not found, check if process still exists. */
        if (fnd_it == 0 && nfscl_procdoesntexist(lp->nfsl_owner) == 0)
                return;

        /* Move the lock owner over to the local list. */
        if (mylfhp == NULL) {
                mylfhp = malloc(sizeof(struct nfscllockownerfh), M_TEMP,
                    M_NOWAIT);
                if (mylfhp == NULL)
                        return;
                mylfhp->nfslfh_len = lp->nfsl_open->nfso_fhlen;
                NFSBCOPY(lp->nfsl_open->nfso_fh, mylfhp->nfslfh_fh,
                    mylfhp->nfslfh_len);
                LIST_INIT(&mylfhp->nfslfh_lock);
                SLIST_INSERT_HEAD(lhp, mylfhp, nfslfh_list);
        }
        LIST_REMOVE(lp, nfsl_list);
        LIST_INSERT_HEAD(&mylfhp->nfslfh_lock, lp, nfsl_list);
}

static int      fake_global;    /* Used to force visibility of MNTK_UNMOUNTF */
/*
 * Called from nfs umount to free up the clientid.
 */
APPLESTATIC void
nfscl_umount(struct nfsmount *nmp, NFSPROC_T *p)
{
        struct nfsclclient *clp;
        struct ucred *cred;
        int igotlock;

        /*
         * For the case that matters, this is the thread that set
         * MNTK_UNMOUNTF, so it will see it set. The code that follows is
         * done to ensure that any thread executing nfscl_getcl() after
         * this time, will see MNTK_UNMOUNTF set. nfscl_getcl() uses the
         * mutex for NFSLOCKCLSTATE(), so it is "m" for the following
         * explanation, courtesy of Alan Cox.
         * What follows is a snippet from Alan Cox's email at:
         * https://docs.FreeBSD.org/cgi/mid.cgi?BANLkTikR3d65zPHo9==08ZfJ2vmqZucEvw
         * 
         * 1. Set MNTK_UNMOUNTF
         * 2. Acquire a standard FreeBSD mutex "m".
         * 3. Update some data structures.
         * 4. Release mutex "m".
         * 
         * Then, other threads that acquire "m" after step 4 has occurred will
         * see MNTK_UNMOUNTF as set.  But, other threads that beat thread X to
         * step 2 may or may not see MNTK_UNMOUNTF as set.
         */
        NFSLOCKCLSTATE();
        if ((nmp->nm_mountp->mnt_kern_flag & MNTK_UNMOUNTF) != 0) {
                fake_global++;
                NFSUNLOCKCLSTATE();
                NFSLOCKCLSTATE();
        }

        clp = nmp->nm_clp;
        if (clp != NULL) {
                if ((clp->nfsc_flags & NFSCLFLAGS_INITED) == 0)
                        panic("nfscl umount");
        
                /*
                 * First, handshake with the nfscl renew thread, to terminate
                 * it.
                 */
                clp->nfsc_flags |= NFSCLFLAGS_UMOUNT;
                while (clp->nfsc_flags & NFSCLFLAGS_HASTHREAD)
                        (void)mtx_sleep(clp, NFSCLSTATEMUTEXPTR, PWAIT,
                            "nfsclumnt", hz);
        
                /*
                 * Now, get the exclusive lock on the client state, so
                 * that no uses of the state are still in progress.
                 */
                do {
                        igotlock = nfsv4_lock(&clp->nfsc_lock, 1, NULL,
                            NFSCLSTATEMUTEXPTR, NULL);
                } while (!igotlock);
                NFSUNLOCKCLSTATE();
        
                /*
                 * Free up all the state. It will expire on the server, but
                 * maybe we should do a SetClientId/SetClientIdConfirm so
                 * the server throws it away?
                 */
                LIST_REMOVE(clp, nfsc_list);
                nfscl_delegreturnall(clp, p);
                cred = newnfs_getcred();
                if (NFSHASNFSV4N(nmp)) {
                        (void)nfsrpc_destroysession(nmp, clp, cred, p);
                        (void)nfsrpc_destroyclient(nmp, clp, cred, p);
                } else
                        (void)nfsrpc_setclient(nmp, clp, 0, cred, p);
                nfscl_cleanclient(clp);
                nmp->nm_clp = NULL;
                NFSFREECRED(cred);
                free(clp, M_NFSCLCLIENT);
        } else
                NFSUNLOCKCLSTATE();
}

/*
 * This function is called when a server replies with NFSERR_STALECLIENTID
 * NFSERR_STALESTATEID or NFSERR_BADSESSION. It traverses the clientid lists,
 * doing Opens and Locks with reclaim. If these fail, it deletes the
 * corresponding state.
 */
static void
nfscl_recover(struct nfsclclient *clp, struct ucred *cred, NFSPROC_T *p)
{
        struct nfsclowner *owp, *nowp;
        struct nfsclopen *op, *nop;
        struct nfscllockowner *lp, *nlp;
        struct nfscllock *lop, *nlop;
        struct nfscldeleg *dp, *ndp, *tdp;
        struct nfsmount *nmp;
        struct ucred *tcred;
        struct nfsclopenhead extra_open;
        struct nfscldeleghead extra_deleg;
        struct nfsreq *rep;
        u_int64_t len;
        u_int32_t delegtype = NFSV4OPEN_DELEGATEWRITE, mode;
        int i, igotlock = 0, error, trycnt, firstlock;
        struct nfscllayout *lyp, *nlyp;

        /*
         * First, lock the client structure, so everyone else will
         * block when trying to use state.
         */
        NFSLOCKCLSTATE();
        clp->nfsc_flags |= NFSCLFLAGS_RECVRINPROG;
        do {
                igotlock = nfsv4_lock(&clp->nfsc_lock, 1, NULL,
                    NFSCLSTATEMUTEXPTR, NULL);
        } while (!igotlock);
        NFSUNLOCKCLSTATE();

        nmp = clp->nfsc_nmp;
        if (nmp == NULL)
                panic("nfscl recover");

        /*
         * For now, just get rid of all layouts. There may be a need
         * to do LayoutCommit Ops with reclaim == true later.
         */
        TAILQ_FOREACH_SAFE(lyp, &clp->nfsc_layout, nfsly_list, nlyp)
                nfscl_freelayout(lyp);
        TAILQ_INIT(&clp->nfsc_layout);
        for (i = 0; i < NFSCLLAYOUTHASHSIZE; i++)
                LIST_INIT(&clp->nfsc_layouthash[i]);

        trycnt = 5;
        do {
                error = nfsrpc_setclient(nmp, clp, 1, cred, p);
        } while ((error == NFSERR_STALECLIENTID ||
             error == NFSERR_BADSESSION ||
             error == NFSERR_STALEDONTRECOVER) && --trycnt > 0);
        if (error) {
                NFSLOCKCLSTATE();
                clp->nfsc_flags &= ~(NFSCLFLAGS_RECOVER |
                    NFSCLFLAGS_RECVRINPROG);
                wakeup(&clp->nfsc_flags);
                nfsv4_unlock(&clp->nfsc_lock, 0);
                NFSUNLOCKCLSTATE();
                return;
        }
        clp->nfsc_flags |= NFSCLFLAGS_HASCLIENTID;
        clp->nfsc_flags &= ~NFSCLFLAGS_RECOVER;

        /*
         * Mark requests already queued on the server, so that they don't
         * initiate another recovery cycle. Any requests already in the
         * queue that handle state information will have the old stale
         * clientid/stateid and will get a NFSERR_STALESTATEID,
         * NFSERR_STALECLIENTID or NFSERR_BADSESSION reply from the server.
         * This will be translated to NFSERR_STALEDONTRECOVER when
         * R_DONTRECOVER is set.
         */
        NFSLOCKREQ();
        TAILQ_FOREACH(rep, &nfsd_reqq, r_chain) {
                if (rep->r_nmp == nmp)
                        rep->r_flags |= R_DONTRECOVER;
        }
        NFSUNLOCKREQ();

        /*
         * Now, mark all delegations "need reclaim".
         */
        TAILQ_FOREACH(dp, &clp->nfsc_deleg, nfsdl_list)
                dp->nfsdl_flags |= NFSCLDL_NEEDRECLAIM;

        TAILQ_INIT(&extra_deleg);
        LIST_INIT(&extra_open);
        /*
         * Now traverse the state lists, doing Open and Lock Reclaims.
         */
        tcred = newnfs_getcred();
        owp = LIST_FIRST(&clp->nfsc_owner);
        while (owp != NULL) {
            nowp = LIST_NEXT(owp, nfsow_list);
            owp->nfsow_seqid = 0;
            op = LIST_FIRST(&owp->nfsow_open);
            while (op != NULL) {
                nop = LIST_NEXT(op, nfso_list);
                if (error != NFSERR_NOGRACE && error != NFSERR_BADSESSION) {
                    /* Search for a delegation to reclaim with the open */
                    TAILQ_FOREACH(dp, &clp->nfsc_deleg, nfsdl_list) {
                        if (!(dp->nfsdl_flags & NFSCLDL_NEEDRECLAIM))
                            continue;
                        if ((dp->nfsdl_flags & NFSCLDL_WRITE)) {
                            mode = NFSV4OPEN_ACCESSWRITE;
                            delegtype = NFSV4OPEN_DELEGATEWRITE;
                        } else {
                            mode = NFSV4OPEN_ACCESSREAD;
                            delegtype = NFSV4OPEN_DELEGATEREAD;
                        }
                        if ((op->nfso_mode & mode) == mode &&
                            op->nfso_fhlen == dp->nfsdl_fhlen &&
                            !NFSBCMP(op->nfso_fh, dp->nfsdl_fh, op->nfso_fhlen))
                            break;
                    }
                    ndp = dp;
                    if (dp == NULL)
                        delegtype = NFSV4OPEN_DELEGATENONE;
                    newnfs_copycred(&op->nfso_cred, tcred);
                    error = nfscl_tryopen(nmp, NULL, op->nfso_fh,
                        op->nfso_fhlen, op->nfso_fh, op->nfso_fhlen,
                        op->nfso_mode, op, NULL, 0, &ndp, 1, delegtype,
                        tcred, p);
                    if (!error) {
                        /* Handle any replied delegation */
                        if (ndp != NULL && ((ndp->nfsdl_flags & NFSCLDL_WRITE)
                            || NFSMNT_RDONLY(nmp->nm_mountp))) {
                            if ((ndp->nfsdl_flags & NFSCLDL_WRITE))
                                mode = NFSV4OPEN_ACCESSWRITE;
                            else
                                mode = NFSV4OPEN_ACCESSREAD;
                            TAILQ_FOREACH(dp, &clp->nfsc_deleg, nfsdl_list) {
                                if (!(dp->nfsdl_flags & NFSCLDL_NEEDRECLAIM))
                                    continue;
                                if ((op->nfso_mode & mode) == mode &&
                                    op->nfso_fhlen == dp->nfsdl_fhlen &&
                                    !NFSBCMP(op->nfso_fh, dp->nfsdl_fh,
                                    op->nfso_fhlen)) {
                                    dp->nfsdl_stateid = ndp->nfsdl_stateid;
                                    dp->nfsdl_sizelimit = ndp->nfsdl_sizelimit;
                                    dp->nfsdl_ace = ndp->nfsdl_ace;
                                    dp->nfsdl_change = ndp->nfsdl_change;
                                    dp->nfsdl_flags &= ~NFSCLDL_NEEDRECLAIM;
                                    if ((ndp->nfsdl_flags & NFSCLDL_RECALL))
                                        dp->nfsdl_flags |= NFSCLDL_RECALL;
                                    free(ndp, M_NFSCLDELEG);
                                    ndp = NULL;
                                    break;
                                }
                            }
                        }
                        if (ndp != NULL)
                            TAILQ_INSERT_HEAD(&extra_deleg, ndp, nfsdl_list);

                        /* and reclaim all byte range locks */
                        lp = LIST_FIRST(&op->nfso_lock);
                        while (lp != NULL) {
                            nlp = LIST_NEXT(lp, nfsl_list);
                            lp->nfsl_seqid = 0;
                            firstlock = 1;
                            lop = LIST_FIRST(&lp->nfsl_lock);
                            while (lop != NULL) {
                                nlop = LIST_NEXT(lop, nfslo_list);
                                if (lop->nfslo_end == NFS64BITSSET)
                                    len = NFS64BITSSET;
                                else
                                    len = lop->nfslo_end - lop->nfslo_first;
                                error = nfscl_trylock(nmp, NULL,
                                    op->nfso_fh, op->nfso_fhlen, lp,
                                    firstlock, 1, lop->nfslo_first, len,
                                    lop->nfslo_type, tcred, p);
                                if (error != 0)
                                    nfscl_freelock(lop, 0);
                                else
                                    firstlock = 0;
                                lop = nlop;
                            }
                            /* If no locks, but a lockowner, just delete it. */
                            if (LIST_EMPTY(&lp->nfsl_lock))
                                nfscl_freelockowner(lp, 0);
                            lp = nlp;
                        }
                    }
                }
                if (error != 0 && error != NFSERR_BADSESSION)
                    nfscl_freeopen(op, 0);
                op = nop;
            }
            owp = nowp;
        }

        /*
         * Now, try and get any delegations not yet reclaimed by cobbling
         * to-gether an appropriate open.
         */
        nowp = NULL;
        dp = TAILQ_FIRST(&clp->nfsc_deleg);
        while (dp != NULL) {
            ndp = TAILQ_NEXT(dp, nfsdl_list);
            if ((dp->nfsdl_flags & NFSCLDL_NEEDRECLAIM)) {
                if (nowp == NULL) {
                    nowp = malloc(
                        sizeof (struct nfsclowner), M_NFSCLOWNER, M_WAITOK);
                    /*
                     * Name must be as long an largest possible
                     * NFSV4CL_LOCKNAMELEN. 12 for now.
                     */
                    NFSBCOPY("RECLAIMDELEG", nowp->nfsow_owner,
                        NFSV4CL_LOCKNAMELEN);
                    LIST_INIT(&nowp->nfsow_open);
                    nowp->nfsow_clp = clp;
                    nowp->nfsow_seqid = 0;
                    nowp->nfsow_defunct = 0;
                    nfscl_lockinit(&nowp->nfsow_rwlock);
                }
                nop = NULL;
                if (error != NFSERR_NOGRACE && error != NFSERR_BADSESSION) {
                    nop = malloc(sizeof (struct nfsclopen) +
                        dp->nfsdl_fhlen - 1, M_NFSCLOPEN, M_WAITOK);
                    nop->nfso_own = nowp;
                    if ((dp->nfsdl_flags & NFSCLDL_WRITE)) {
                        nop->nfso_mode = NFSV4OPEN_ACCESSWRITE;
                        delegtype = NFSV4OPEN_DELEGATEWRITE;
                    } else {
                        nop->nfso_mode = NFSV4OPEN_ACCESSREAD;
                        delegtype = NFSV4OPEN_DELEGATEREAD;
                    }
                    nop->nfso_opencnt = 0;
                    nop->nfso_posixlock = 1;
                    nop->nfso_fhlen = dp->nfsdl_fhlen;
                    NFSBCOPY(dp->nfsdl_fh, nop->nfso_fh, dp->nfsdl_fhlen);
                    LIST_INIT(&nop->nfso_lock);
                    nop->nfso_stateid.seqid = 0;
                    nop->nfso_stateid.other[0] = 0;
                    nop->nfso_stateid.other[1] = 0;
                    nop->nfso_stateid.other[2] = 0;
                    newnfs_copycred(&dp->nfsdl_cred, tcred);
                    newnfs_copyincred(tcred, &nop->nfso_cred);
                    tdp = NULL;
                    error = nfscl_tryopen(nmp, NULL, nop->nfso_fh,
                        nop->nfso_fhlen, nop->nfso_fh, nop->nfso_fhlen,
                        nop->nfso_mode, nop, NULL, 0, &tdp, 1,
                        delegtype, tcred, p);
                    if (tdp != NULL) {
                        if ((tdp->nfsdl_flags & NFSCLDL_WRITE))
                            mode = NFSV4OPEN_ACCESSWRITE;
                        else
                            mode = NFSV4OPEN_ACCESSREAD;
                        if ((nop->nfso_mode & mode) == mode &&
                            nop->nfso_fhlen == tdp->nfsdl_fhlen &&
                            !NFSBCMP(nop->nfso_fh, tdp->nfsdl_fh,
                            nop->nfso_fhlen)) {
                            dp->nfsdl_stateid = tdp->nfsdl_stateid;
                            dp->nfsdl_sizelimit = tdp->nfsdl_sizelimit;
                            dp->nfsdl_ace = tdp->nfsdl_ace;
                            dp->nfsdl_change = tdp->nfsdl_change;
                            dp->nfsdl_flags &= ~NFSCLDL_NEEDRECLAIM;
                            if ((tdp->nfsdl_flags & NFSCLDL_RECALL))
                                dp->nfsdl_flags |= NFSCLDL_RECALL;
                            free(tdp, M_NFSCLDELEG);
                        } else {
                            TAILQ_INSERT_HEAD(&extra_deleg, tdp, nfsdl_list);
                        }
                    }
                }
                if (error) {
                    if (nop != NULL)
                        free(nop, M_NFSCLOPEN);
                    /*
                     * Couldn't reclaim it, so throw the state
                     * away. Ouch!!
                     */
                    nfscl_cleandeleg(dp);
                    nfscl_freedeleg(&clp->nfsc_deleg, dp);
                } else {
                    LIST_INSERT_HEAD(&extra_open, nop, nfso_list);
                }
            }
            dp = ndp;
        }

        /*
         * Now, get rid of extra Opens and Delegations.
         */
        LIST_FOREACH_SAFE(op, &extra_open, nfso_list, nop) {
                do {
                        newnfs_copycred(&op->nfso_cred, tcred);
                        error = nfscl_tryclose(op, tcred, nmp, p);
                        if (error == NFSERR_GRACE)
                                (void) nfs_catnap(PZERO, error, "nfsexcls");
                } while (error == NFSERR_GRACE);
                LIST_REMOVE(op, nfso_list);
                free(op, M_NFSCLOPEN);
        }
        if (nowp != NULL)
                free(nowp, M_NFSCLOWNER);

        TAILQ_FOREACH_SAFE(dp, &extra_deleg, nfsdl_list, ndp) {
                do {
                        newnfs_copycred(&dp->nfsdl_cred, tcred);
                        error = nfscl_trydelegreturn(dp, tcred, nmp, p);
                        if (error == NFSERR_GRACE)
                                (void) nfs_catnap(PZERO, error, "nfsexdlg");
                } while (error == NFSERR_GRACE);
                TAILQ_REMOVE(&extra_deleg, dp, nfsdl_list);
                free(dp, M_NFSCLDELEG);
        }

        /* For NFSv4.1 or later, do a RECLAIM_COMPLETE. */
        if (NFSHASNFSV4N(nmp))
                (void)nfsrpc_reclaimcomplete(nmp, cred, p);

        NFSLOCKCLSTATE();
        clp->nfsc_flags &= ~NFSCLFLAGS_RECVRINPROG;
        wakeup(&clp->nfsc_flags);
        nfsv4_unlock(&clp->nfsc_lock, 0);
        NFSUNLOCKCLSTATE();
        NFSFREECRED(tcred);
}

/*
 * This function is called when a server replies with NFSERR_EXPIRED.
 * It deletes all state for the client and does a fresh SetClientId/confirm.
 * XXX Someday it should post a signal to the process(es) that hold the
 * state, so they know that lock state has been lost.
 */
APPLESTATIC int
nfscl_hasexpired(struct nfsclclient *clp, u_int32_t clidrev, NFSPROC_T *p)
{
        struct nfsmount *nmp;
        struct ucred *cred;
        int igotlock = 0, error, trycnt;

        /*
         * If the clientid has gone away or a new SetClientid has already
         * been done, just return ok.
         */
        if (clp == NULL || clidrev != clp->nfsc_clientidrev)
                return (0);

        /*
         * First, lock the client structure, so everyone else will
         * block when trying to use state. Also, use NFSCLFLAGS_EXPIREIT so
         * that only one thread does the work.
         */
        NFSLOCKCLSTATE();
        clp->nfsc_flags |= NFSCLFLAGS_EXPIREIT;
        do {
                igotlock = nfsv4_lock(&clp->nfsc_lock, 1, NULL,
                    NFSCLSTATEMUTEXPTR, NULL);
        } while (!igotlock && (clp->nfsc_flags & NFSCLFLAGS_EXPIREIT));
        if ((clp->nfsc_flags & NFSCLFLAGS_EXPIREIT) == 0) {
                if (igotlock)
                        nfsv4_unlock(&clp->nfsc_lock, 0);
                NFSUNLOCKCLSTATE();
                return (0);
        }
        clp->nfsc_flags |= NFSCLFLAGS_RECVRINPROG;
        NFSUNLOCKCLSTATE();

        nmp = clp->nfsc_nmp;
        if (nmp == NULL)
                panic("nfscl expired");
        cred = newnfs_getcred();
        trycnt = 5;
        do {
                error = nfsrpc_setclient(nmp, clp, 0, cred, p);
        } while ((error == NFSERR_STALECLIENTID ||
             error == NFSERR_BADSESSION ||
             error == NFSERR_STALEDONTRECOVER) && --trycnt > 0);
        if (error) {
                NFSLOCKCLSTATE();
                clp->nfsc_flags &= ~NFSCLFLAGS_RECOVER;
        } else {
                /*
                 * Expire the state for the client.
                 */
                nfscl_expireclient(clp, nmp, cred, p);
                NFSLOCKCLSTATE();
                clp->nfsc_flags |= NFSCLFLAGS_HASCLIENTID;
                clp->nfsc_flags &= ~NFSCLFLAGS_RECOVER;
        }
        clp->nfsc_flags &= ~(NFSCLFLAGS_EXPIREIT | NFSCLFLAGS_RECVRINPROG);
        wakeup(&clp->nfsc_flags);
        nfsv4_unlock(&clp->nfsc_lock, 0);
        NFSUNLOCKCLSTATE();
        NFSFREECRED(cred);
        return (error);
}

/*
 * This function inserts a lock in the list after insert_lop.
 */
static void
nfscl_insertlock(struct nfscllockowner *lp, struct nfscllock *new_lop,
    struct nfscllock *insert_lop, int local)
{

        if ((struct nfscllockowner *)insert_lop == lp)
                LIST_INSERT_HEAD(&lp->nfsl_lock, new_lop, nfslo_list);
        else
                LIST_INSERT_AFTER(insert_lop, new_lop, nfslo_list);
        if (local)
                nfsstatsv1.cllocallocks++;
        else
                nfsstatsv1.cllocks++;
}

/*
 * This function updates the locking for a lock owner and given file. It
 * maintains a list of lock ranges ordered on increasing file offset that
 * are NFSCLLOCK_READ or NFSCLLOCK_WRITE and non-overlapping (aka POSIX style).
 * It always adds new_lop to the list and sometimes uses the one pointed
 * at by other_lopp.
 * Returns 1 if the locks were modified, 0 otherwise.
 */
static int
nfscl_updatelock(struct nfscllockowner *lp, struct nfscllock **new_lopp,
    struct nfscllock **other_lopp, int local)
{
        struct nfscllock *new_lop = *new_lopp;
        struct nfscllock *lop, *tlop, *ilop;
        struct nfscllock *other_lop;
        int unlock = 0, modified = 0;
        u_int64_t tmp;

        /*
         * Work down the list until the lock is merged.
         */
        if (new_lop->nfslo_type == F_UNLCK)
                unlock = 1;
        ilop = (struct nfscllock *)lp;
        lop = LIST_FIRST(&lp->nfsl_lock);
        while (lop != NULL) {
            /*
             * Only check locks for this file that aren't before the start of
             * new lock's range.
             */
            if (lop->nfslo_end >= new_lop->nfslo_first) {
                if (new_lop->nfslo_end < lop->nfslo_first) {
                    /*
                     * If the new lock ends before the start of the
                     * current lock's range, no merge, just insert
                     * the new lock.
                     */
                    break;
                }
                if (new_lop->nfslo_type == lop->nfslo_type ||
                    (new_lop->nfslo_first <= lop->nfslo_first &&
                     new_lop->nfslo_end >= lop->nfslo_end)) {
                    /*
                     * This lock can be absorbed by the new lock/unlock.
                     * This happens when it covers the entire range
                     * of the old lock or is contiguous
                     * with the old lock and is of the same type or an
                     * unlock.
                     */
                    if (new_lop->nfslo_type != lop->nfslo_type ||
                        new_lop->nfslo_first != lop->nfslo_first ||
                        new_lop->nfslo_end != lop->nfslo_end)
                        modified = 1;
                    if (lop->nfslo_first < new_lop->nfslo_first)
                        new_lop->nfslo_first = lop->nfslo_first;
                    if (lop->nfslo_end > new_lop->nfslo_end)
                        new_lop->nfslo_end = lop->nfslo_end;
                    tlop = lop;
                    lop = LIST_NEXT(lop, nfslo_list);
                    nfscl_freelock(tlop, local);
                    continue;
                }

                /*
                 * All these cases are for contiguous locks that are not the
                 * same type, so they can't be merged.
                 */
                if (new_lop->nfslo_first <= lop->nfslo_first) {
                    /*
                     * This case is where the new lock overlaps with the
                     * first part of the old lock. Move the start of the
                     * old lock to just past the end of the new lock. The
                     * new lock will be inserted in front of the old, since
                     * ilop hasn't been updated. (We are done now.)
                     */
                    if (lop->nfslo_first != new_lop->nfslo_end) {
                        lop->nfslo_first = new_lop->nfslo_end;
                        modified = 1;
                    }
                    break;
                }
                if (new_lop->nfslo_end >= lop->nfslo_end) {
                    /*
                     * This case is where the new lock overlaps with the
                     * end of the old lock's range. Move the old lock's
                     * end to just before the new lock's first and insert
                     * the new lock after the old lock.
                     * Might not be done yet, since the new lock could
                     * overlap further locks with higher ranges.
                     */
                    if (lop->nfslo_end != new_lop->nfslo_first) {
                        lop->nfslo_end = new_lop->nfslo_first;
                        modified = 1;
                    }
                    ilop = lop;
                    lop = LIST_NEXT(lop, nfslo_list);
                    continue;
                }
                /*
                 * The final case is where the new lock's range is in the
                 * middle of the current lock's and splits the current lock
                 * up. Use *other_lopp to handle the second part of the
                 * split old lock range. (We are done now.)
                 * For unlock, we use new_lop as other_lop and tmp, since
                 * other_lop and new_lop are the same for this case.
                 * We noted the unlock case above, so we don't need
                 * new_lop->nfslo_type any longer.
                 */
                tmp = new_lop->nfslo_first;
                if (unlock) {
                    other_lop = new_lop;
                    *new_lopp = NULL;
                } else {
                    other_lop = *other_lopp;
                    *other_lopp = NULL;
                }
                other_lop->nfslo_first = new_lop->nfslo_end;
                other_lop->nfslo_end = lop->nfslo_end;
                other_lop->nfslo_type = lop->nfslo_type;
                lop->nfslo_end = tmp;
                nfscl_insertlock(lp, other_lop, lop, local);
                ilop = lop;
                modified = 1;
                break;
            }
            ilop = lop;
            lop = LIST_NEXT(lop, nfslo_list);
            if (lop == NULL)
                break;
        }

        /*
         * Insert the new lock in the list at the appropriate place.
         */
        if (!unlock) {
                nfscl_insertlock(lp, new_lop, ilop, local);
                *new_lopp = NULL;
                modified = 1;
        }
        return (modified);
}

/*
 * This function must be run as a kernel thread.
 * It does Renew Ops and recovery, when required.
 */
APPLESTATIC void
nfscl_renewthread(struct nfsclclient *clp, NFSPROC_T *p)
{
        struct nfsclowner *owp, *nowp;
        struct nfsclopen *op;
        struct nfscllockowner *lp, *nlp;
        struct nfscldeleghead dh;
        struct nfscldeleg *dp, *ndp;
        struct ucred *cred;
        u_int32_t clidrev;
        int error, cbpathdown, islept, igotlock, ret, clearok;
        uint32_t recover_done_time = 0;
        time_t mytime;
        static time_t prevsec = 0;
        struct nfscllockownerfh *lfhp, *nlfhp;
        struct nfscllockownerfhhead lfh;
        struct nfscllayout *lyp, *nlyp;
        struct nfscldevinfo *dip, *ndip;
        struct nfscllayouthead rlh;
        struct nfsclrecalllayout *recallp;
        struct nfsclds *dsp;

        cred = newnfs_getcred();
        NFSLOCKCLSTATE();
        clp->nfsc_flags |= NFSCLFLAGS_HASTHREAD;
        NFSUNLOCKCLSTATE();
        for(;;) {
                newnfs_setroot(cred);
                cbpathdown = 0;
                if (clp->nfsc_flags & NFSCLFLAGS_RECOVER) {
                        /*
                         * Only allow one recover within 1/2 of the lease
                         * duration (nfsc_renew).
                         */
                        if (recover_done_time < NFSD_MONOSEC) {
                                recover_done_time = NFSD_MONOSEC +
                                    clp->nfsc_renew;
                                NFSCL_DEBUG(1, "Doing recovery..\n");
                                nfscl_recover(clp, cred, p);
                        } else {
                                NFSCL_DEBUG(1, "Clear Recovery dt=%u ms=%jd\n",
                                    recover_done_time, (intmax_t)NFSD_MONOSEC);
                                NFSLOCKCLSTATE();
                                clp->nfsc_flags &= ~NFSCLFLAGS_RECOVER;
                                NFSUNLOCKCLSTATE();
                        }
                }
                if (clp->nfsc_expire <= NFSD_MONOSEC &&
                    (clp->nfsc_flags & NFSCLFLAGS_HASCLIENTID)) {
                        clp->nfsc_expire = NFSD_MONOSEC + clp->nfsc_renew;
                        clidrev = clp->nfsc_clientidrev;
                        error = nfsrpc_renew(clp, NULL, cred, p);
                        if (error == NFSERR_CBPATHDOWN)
                            cbpathdown = 1;
                        else if (error == NFSERR_STALECLIENTID ||
                            error == NFSERR_BADSESSION) {
                            NFSLOCKCLSTATE();
                            clp->nfsc_flags |= NFSCLFLAGS_RECOVER;
                            NFSUNLOCKCLSTATE();
                        } else if (error == NFSERR_EXPIRED)
                            (void) nfscl_hasexpired(clp, clidrev, p);
                }

checkdsrenew:
                if (NFSHASNFSV4N(clp->nfsc_nmp)) {
                        /* Do renews for any DS sessions. */
                        NFSLOCKMNT(clp->nfsc_nmp);
                        /* Skip first entry, since the MDS is handled above. */
                        dsp = TAILQ_FIRST(&clp->nfsc_nmp->nm_sess);
                        if (dsp != NULL)
                                dsp = TAILQ_NEXT(dsp, nfsclds_list);
                        while (dsp != NULL) {
                                if (dsp->nfsclds_expire <= NFSD_MONOSEC &&
                                    dsp->nfsclds_sess.nfsess_defunct == 0) {
                                        dsp->nfsclds_expire = NFSD_MONOSEC +
                                            clp->nfsc_renew;
                                        NFSUNLOCKMNT(clp->nfsc_nmp);
                                        (void)nfsrpc_renew(clp, dsp, cred, p);
                                        goto checkdsrenew;
                                }
                                dsp = TAILQ_NEXT(dsp, nfsclds_list);
                        }
                        NFSUNLOCKMNT(clp->nfsc_nmp);
                }

                TAILQ_INIT(&dh);
                NFSLOCKCLSTATE();
                if (cbpathdown)
                        /* It's a Total Recall! */
                        nfscl_totalrecall(clp);

                /*
                 * Now, handle defunct owners.
                 */
                LIST_FOREACH_SAFE(owp, &clp->nfsc_owner, nfsow_list, nowp) {
                        if (LIST_EMPTY(&owp->nfsow_open)) {
                                if (owp->nfsow_defunct != 0)
                                        nfscl_freeopenowner(owp, 0);
                        }
                }

                /*
                 * Do the recall on any delegations. To avoid trouble, always
                 * come back up here after having slept.
                 */
                igotlock = 0;
tryagain:
                dp = TAILQ_FIRST(&clp->nfsc_deleg);
                while (dp != NULL) {
                        ndp = TAILQ_NEXT(dp, nfsdl_list);
                        if ((dp->nfsdl_flags & NFSCLDL_RECALL)) {
                                /*
                                 * Wait for outstanding I/O ops to be done.
                                 */
                                if (dp->nfsdl_rwlock.nfslock_usecnt > 0) {
                                    if (igotlock) {
                                        nfsv4_unlock(&clp->nfsc_lock, 0);
                                        igotlock = 0;
                                    }
                                    dp->nfsdl_rwlock.nfslock_lock |=
                                        NFSV4LOCK_WANTED;
                                    (void) nfsmsleep(&dp->nfsdl_rwlock,
                                        NFSCLSTATEMUTEXPTR, PZERO, "nfscld",
                                        NULL);
                                    goto tryagain;
                                }
                                while (!igotlock) {
                                    igotlock = nfsv4_lock(&clp->nfsc_lock, 1,
                                        &islept, NFSCLSTATEMUTEXPTR, NULL);
                                    if (islept)
                                        goto tryagain;
                                }
                                NFSUNLOCKCLSTATE();
                                newnfs_copycred(&dp->nfsdl_cred, cred);
                                ret = nfscl_recalldeleg(clp, clp->nfsc_nmp, dp,
                                    NULL, cred, p, 1);
                                if (!ret) {
                                    nfscl_cleandeleg(dp);
                                    TAILQ_REMOVE(&clp->nfsc_deleg, dp,
                                        nfsdl_list);
                                    LIST_REMOVE(dp, nfsdl_hash);
                                    TAILQ_INSERT_HEAD(&dh, dp, nfsdl_list);
                                    nfscl_delegcnt--;
                                    nfsstatsv1.cldelegates--;
                                }
                                NFSLOCKCLSTATE();
                        }
                        dp = ndp;
                }

                /*
                 * Clear out old delegations, if we are above the high water
                 * mark. Only clear out ones with no state related to them.
                 * The tailq list is in LRU order.
                 */
                dp = TAILQ_LAST(&clp->nfsc_deleg, nfscldeleghead);
                while (nfscl_delegcnt > nfscl_deleghighwater && dp != NULL) {
                    ndp = TAILQ_PREV(dp, nfscldeleghead, nfsdl_list);
                    if (dp->nfsdl_rwlock.nfslock_usecnt == 0 &&
                        dp->nfsdl_rwlock.nfslock_lock == 0 &&
                        dp->nfsdl_timestamp < NFSD_MONOSEC &&
                        (dp->nfsdl_flags & (NFSCLDL_RECALL | NFSCLDL_ZAPPED |
                          NFSCLDL_NEEDRECLAIM | NFSCLDL_DELEGRET)) == 0) {
                        clearok = 1;
                        LIST_FOREACH(owp, &dp->nfsdl_owner, nfsow_list) {
                            op = LIST_FIRST(&owp->nfsow_open);
                            if (op != NULL) {
                                clearok = 0;
                                break;
                            }
                        }
                        if (clearok) {
                            LIST_FOREACH(lp, &dp->nfsdl_lock, nfsl_list) {
                                if (!LIST_EMPTY(&lp->nfsl_lock)) {
                                    clearok = 0;
                                    break;
                                }
                            }
                        }
                        if (clearok) {
                            TAILQ_REMOVE(&clp->nfsc_deleg, dp, nfsdl_list);
                            LIST_REMOVE(dp, nfsdl_hash);
                            TAILQ_INSERT_HEAD(&dh, dp, nfsdl_list);
                            nfscl_delegcnt--;
                            nfsstatsv1.cldelegates--;
                        }
                    }
                    dp = ndp;
                }
                if (igotlock)
                        nfsv4_unlock(&clp->nfsc_lock, 0);

                /*
                 * Do the recall on any layouts. To avoid trouble, always
                 * come back up here after having slept.
                 */
                TAILQ_INIT(&rlh);
tryagain2:
                TAILQ_FOREACH_SAFE(lyp, &clp->nfsc_layout, nfsly_list, nlyp) {
                        if ((lyp->nfsly_flags & NFSLY_RECALL) != 0) {
                                /*
                                 * Wait for outstanding I/O ops to be done.
                                 */
                                if (lyp->nfsly_lock.nfslock_usecnt > 0 ||
                                    (lyp->nfsly_lock.nfslock_lock &
                                     NFSV4LOCK_LOCK) != 0) {
                                        lyp->nfsly_lock.nfslock_lock |=
                                            NFSV4LOCK_WANTED;
                                        nfsmsleep(&lyp->nfsly_lock.nfslock_lock,
                                            NFSCLSTATEMUTEXPTR, PZERO, "nfslyp",
                                            NULL);
                                        goto tryagain2;
                                }
                                /* Move the layout to the recall list. */
                                TAILQ_REMOVE(&clp->nfsc_layout, lyp,
                                    nfsly_list);
                                LIST_REMOVE(lyp, nfsly_hash);
                                TAILQ_INSERT_HEAD(&rlh, lyp, nfsly_list);

                                /* Handle any layout commits. */
                                if (!NFSHASNOLAYOUTCOMMIT(clp->nfsc_nmp) &&
                                    (lyp->nfsly_flags & NFSLY_WRITTEN) != 0) {
                                        lyp->nfsly_flags &= ~NFSLY_WRITTEN;
                                        NFSUNLOCKCLSTATE();
                                        NFSCL_DEBUG(3, "do layoutcommit\n");
                                        nfscl_dolayoutcommit(clp->nfsc_nmp, lyp,
                                            cred, p);
                                        NFSLOCKCLSTATE();
                                        goto tryagain2;
                                }
                        }
                }

                /* Now, look for stale layouts. */
                lyp = TAILQ_LAST(&clp->nfsc_layout, nfscllayouthead);
                while (lyp != NULL) {
                        nlyp = TAILQ_PREV(lyp, nfscllayouthead, nfsly_list);
                        if (lyp->nfsly_timestamp < NFSD_MONOSEC &&
                            (lyp->nfsly_flags & NFSLY_RECALL) == 0 &&
                            lyp->nfsly_lock.nfslock_usecnt == 0 &&
                            lyp->nfsly_lock.nfslock_lock == 0) {
                                NFSCL_DEBUG(4, "ret stale lay=%d\n",
                                    nfscl_layoutcnt);
                                recallp = malloc(sizeof(*recallp),
                                    M_NFSLAYRECALL, M_NOWAIT);
                                if (recallp == NULL)
                                        break;
                                (void)nfscl_layoutrecall(NFSLAYOUTRETURN_FILE,
                                    lyp, NFSLAYOUTIOMODE_ANY, 0, UINT64_MAX,
                                    lyp->nfsly_stateid.seqid, 0, 0, NULL,
                                    recallp);
                        }
                        lyp = nlyp;
                }

                /*
                 * Free up any unreferenced device info structures.
                 */
                LIST_FOREACH_SAFE(dip, &clp->nfsc_devinfo, nfsdi_list, ndip) {
                        if (dip->nfsdi_layoutrefs == 0 &&
                            dip->nfsdi_refcnt == 0) {
                                NFSCL_DEBUG(4, "freeing devinfo\n");
                                LIST_REMOVE(dip, nfsdi_list);
                                nfscl_freedevinfo(dip);
                        }
                }
                NFSUNLOCKCLSTATE();

                /* Do layout return(s), as required. */
                TAILQ_FOREACH_SAFE(lyp, &rlh, nfsly_list, nlyp) {
                        TAILQ_REMOVE(&rlh, lyp, nfsly_list);
                        NFSCL_DEBUG(4, "ret layout\n");
                        nfscl_layoutreturn(clp->nfsc_nmp, lyp, cred, p);
                        nfscl_freelayout(lyp);
                }

                /*
                 * Delegreturn any delegations cleaned out or recalled.
                 */
                TAILQ_FOREACH_SAFE(dp, &dh, nfsdl_list, ndp) {
                        newnfs_copycred(&dp->nfsdl_cred, cred);
                        (void) nfscl_trydelegreturn(dp, cred, clp->nfsc_nmp, p);
                        TAILQ_REMOVE(&dh, dp, nfsdl_list);
                        free(dp, M_NFSCLDELEG);
                }

                SLIST_INIT(&lfh);
                /*
                 * Call nfscl_cleanupkext() once per second to check for
                 * open/lock owners where the process has exited.
                 */
                mytime = NFSD_MONOSEC;
                if (prevsec != mytime) {
                        prevsec = mytime;
                        nfscl_cleanupkext(clp, &lfh);
                }

                /*
                 * Do a ReleaseLockOwner for all lock owners where the
                 * associated process no longer exists, as found by
                 * nfscl_cleanupkext().
                 */
                newnfs_setroot(cred);
                SLIST_FOREACH_SAFE(lfhp, &lfh, nfslfh_list, nlfhp) {
                        LIST_FOREACH_SAFE(lp, &lfhp->nfslfh_lock, nfsl_list,
                            nlp) {
                                (void)nfsrpc_rellockown(clp->nfsc_nmp, lp,
                                    lfhp->nfslfh_fh, lfhp->nfslfh_len, cred,
                                    p);
                                nfscl_freelockowner(lp, 0);
                        }
                        free(lfhp, M_TEMP);
                }
                SLIST_INIT(&lfh);

                NFSLOCKCLSTATE();
                if ((clp->nfsc_flags & NFSCLFLAGS_RECOVER) == 0)
                        (void)mtx_sleep(clp, NFSCLSTATEMUTEXPTR, PWAIT, "nfscl",
                            hz);
                if (clp->nfsc_flags & NFSCLFLAGS_UMOUNT) {
                        clp->nfsc_flags &= ~NFSCLFLAGS_HASTHREAD;
                        NFSUNLOCKCLSTATE();
                        NFSFREECRED(cred);
                        wakeup((caddr_t)clp);
                        return;
                }
                NFSUNLOCKCLSTATE();
        }
}

/*
 * Initiate state recovery. Called when NFSERR_STALECLIENTID,
 * NFSERR_STALESTATEID or NFSERR_BADSESSION is received.
 */
APPLESTATIC void
nfscl_initiate_recovery(struct nfsclclient *clp)
{

        if (clp == NULL)
                return;
        NFSLOCKCLSTATE();
        clp->nfsc_flags |= NFSCLFLAGS_RECOVER;
        NFSUNLOCKCLSTATE();
        wakeup((caddr_t)clp);
}

/*
 * Dump out the state stuff for debugging.
 */
APPLESTATIC void
nfscl_dumpstate(struct nfsmount *nmp, int openowner, int opens,
    int lockowner, int locks)
{
        struct nfsclclient *clp;
        struct nfsclowner *owp;
        struct nfsclopen *op;
        struct nfscllockowner *lp;
        struct nfscllock *lop;
        struct nfscldeleg *dp;

        clp = nmp->nm_clp;
        if (clp == NULL) {
                printf("nfscl dumpstate NULL clp\n");
                return;
        }
        NFSLOCKCLSTATE();
        TAILQ_FOREACH(dp, &clp->nfsc_deleg, nfsdl_list) {
          LIST_FOREACH(owp, &dp->nfsdl_owner, nfsow_list) {
            if (openowner && !LIST_EMPTY(&owp->nfsow_open))
                printf("owner=0x%x 0x%x 0x%x 0x%x seqid=%d\n",
                    owp->nfsow_owner[0], owp->nfsow_owner[1],
                    owp->nfsow_owner[2], owp->nfsow_owner[3],
                    owp->nfsow_seqid);
            LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                if (opens)
                    printf("open st=0x%x 0x%x 0x%x cnt=%d fh12=0x%x\n",
                        op->nfso_stateid.other[0], op->nfso_stateid.other[1],
                        op->nfso_stateid.other[2], op->nfso_opencnt,
                        op->nfso_fh[12]);
                LIST_FOREACH(lp, &op->nfso_lock, nfsl_list) {
                    if (lockowner)
                        printf("lckown=0x%x 0x%x 0x%x 0x%x seqid=%d st=0x%x 0x%x 0x%x\n",
                            lp->nfsl_owner[0], lp->nfsl_owner[1],
                            lp->nfsl_owner[2], lp->nfsl_owner[3],
                            lp->nfsl_seqid,
                            lp->nfsl_stateid.other[0], lp->nfsl_stateid.other[1],
                            lp->nfsl_stateid.other[2]);
                    LIST_FOREACH(lop, &lp->nfsl_lock, nfslo_list) {
                        if (locks)
#ifdef __FreeBSD__
                            printf("lck typ=%d fst=%ju end=%ju\n",
                                lop->nfslo_type, (intmax_t)lop->nfslo_first,
                                (intmax_t)lop->nfslo_end);
#else
                            printf("lck typ=%d fst=%qd end=%qd\n",
                                lop->nfslo_type, lop->nfslo_first,
                                lop->nfslo_end);
#endif
                    }
                }
            }
          }
        }
        LIST_FOREACH(owp, &clp->nfsc_owner, nfsow_list) {
            if (openowner && !LIST_EMPTY(&owp->nfsow_open))
                printf("owner=0x%x 0x%x 0x%x 0x%x seqid=%d\n",
                    owp->nfsow_owner[0], owp->nfsow_owner[1],
                    owp->nfsow_owner[2], owp->nfsow_owner[3],
                    owp->nfsow_seqid);
            LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                if (opens)
                    printf("open st=0x%x 0x%x 0x%x cnt=%d fh12=0x%x\n",
                        op->nfso_stateid.other[0], op->nfso_stateid.other[1],
                        op->nfso_stateid.other[2], op->nfso_opencnt,
                        op->nfso_fh[12]);
                LIST_FOREACH(lp, &op->nfso_lock, nfsl_list) {
                    if (lockowner)
                        printf("lckown=0x%x 0x%x 0x%x 0x%x seqid=%d st=0x%x 0x%x 0x%x\n",
                            lp->nfsl_owner[0], lp->nfsl_owner[1],
                            lp->nfsl_owner[2], lp->nfsl_owner[3],
                            lp->nfsl_seqid,
                            lp->nfsl_stateid.other[0], lp->nfsl_stateid.other[1],
                            lp->nfsl_stateid.other[2]);
                    LIST_FOREACH(lop, &lp->nfsl_lock, nfslo_list) {
                        if (locks)
#ifdef __FreeBSD__
                            printf("lck typ=%d fst=%ju end=%ju\n",
                                lop->nfslo_type, (intmax_t)lop->nfslo_first,
                                (intmax_t)lop->nfslo_end);
#else
                            printf("lck typ=%d fst=%qd end=%qd\n",
                                lop->nfslo_type, lop->nfslo_first,
                                lop->nfslo_end);
#endif
                    }
                }
            }
        }
        NFSUNLOCKCLSTATE();
}

/*
 * Check for duplicate open owners and opens.
 * (Only used as a diagnostic aid.)
 */
APPLESTATIC void
nfscl_dupopen(vnode_t vp, int dupopens)
{
        struct nfsclclient *clp;
        struct nfsclowner *owp, *owp2;
        struct nfsclopen *op, *op2;
        struct nfsfh *nfhp;

        clp = VFSTONFS(vnode_mount(vp))->nm_clp;
        if (clp == NULL) {
                printf("nfscl dupopen NULL clp\n");
                return;
        }
        nfhp = VTONFS(vp)->n_fhp;
        NFSLOCKCLSTATE();

        /*
         * First, search for duplicate owners.
         * These should never happen!
         */
        LIST_FOREACH(owp2, &clp->nfsc_owner, nfsow_list) {
            LIST_FOREACH(owp, &clp->nfsc_owner, nfsow_list) {
                if (owp != owp2 &&
                    !NFSBCMP(owp->nfsow_owner, owp2->nfsow_owner,
                    NFSV4CL_LOCKNAMELEN)) {
                        NFSUNLOCKCLSTATE();
                        printf("DUP OWNER\n");
                        nfscl_dumpstate(VFSTONFS(vnode_mount(vp)), 1, 1, 0, 0);
                        return;
                }
            }
        }

        /*
         * Now, search for duplicate stateids.
         * These shouldn't happen, either.
         */
        LIST_FOREACH(owp2, &clp->nfsc_owner, nfsow_list) {
            LIST_FOREACH(op2, &owp2->nfsow_open, nfso_list) {
                LIST_FOREACH(owp, &clp->nfsc_owner, nfsow_list) {
                    LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                        if (op != op2 &&
                            (op->nfso_stateid.other[0] != 0 ||
                             op->nfso_stateid.other[1] != 0 ||
                             op->nfso_stateid.other[2] != 0) &&
                            op->nfso_stateid.other[0] == op2->nfso_stateid.other[0] &&
                            op->nfso_stateid.other[1] == op2->nfso_stateid.other[1] &&
                            op->nfso_stateid.other[2] == op2->nfso_stateid.other[2]) {
                            NFSUNLOCKCLSTATE();
                            printf("DUP STATEID\n");
                            nfscl_dumpstate(VFSTONFS(vnode_mount(vp)), 1, 1, 0,
                                0);
                            return;
                        }
                    }
                }
            }
        }

        /*
         * Now search for duplicate opens.
         * Duplicate opens for the same owner
         * should never occur. Other duplicates are
         * possible and are checked for if "dupopens"
         * is true.
         */
        LIST_FOREACH(owp2, &clp->nfsc_owner, nfsow_list) {
            LIST_FOREACH(op2, &owp2->nfsow_open, nfso_list) {
                if (nfhp->nfh_len == op2->nfso_fhlen &&
                    !NFSBCMP(nfhp->nfh_fh, op2->nfso_fh, nfhp->nfh_len)) {
                    LIST_FOREACH(owp, &clp->nfsc_owner, nfsow_list) {
                        LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                            if (op != op2 && nfhp->nfh_len == op->nfso_fhlen &&
                                !NFSBCMP(nfhp->nfh_fh, op->nfso_fh, nfhp->nfh_len) &&
                                (!NFSBCMP(op->nfso_own->nfsow_owner,
                                 op2->nfso_own->nfsow_owner, NFSV4CL_LOCKNAMELEN) ||
                                 dupopens)) {
                                if (!NFSBCMP(op->nfso_own->nfsow_owner,
                                    op2->nfso_own->nfsow_owner, NFSV4CL_LOCKNAMELEN)) {
                                    NFSUNLOCKCLSTATE();
                                    printf("BADDUP OPEN\n");
                                } else {
                                    NFSUNLOCKCLSTATE();
                                    printf("DUP OPEN\n");
                                }
                                nfscl_dumpstate(VFSTONFS(vnode_mount(vp)), 1, 1,
                                    0, 0);
                                return;
                            }
                        }
                    }
                }
            }
        }
        NFSUNLOCKCLSTATE();
}

/*
 * During close, find an open that needs to be dereferenced and
 * dereference it. If there are no more opens for this file,
 * log a message to that effect.
 * Opens aren't actually Close'd until VOP_INACTIVE() is performed
 * on the file's vnode.
 * This is the safe way, since it is difficult to identify
 * which open the close is for and I/O can be performed after the
 * close(2) system call when a file is mmap'd.
 * If it returns 0 for success, there will be a referenced
 * clp returned via clpp.
 */
APPLESTATIC int
nfscl_getclose(vnode_t vp, struct nfsclclient **clpp)
{
        struct nfsclclient *clp;
        struct nfsclowner *owp;
        struct nfsclopen *op;
        struct nfscldeleg *dp;
        struct nfsfh *nfhp;
        int error, notdecr;

        error = nfscl_getcl(vnode_mount(vp), NULL, NULL, 1, &clp);
        if (error)
                return (error);
        *clpp = clp;

        nfhp = VTONFS(vp)->n_fhp;
        notdecr = 1;
        NFSLOCKCLSTATE();
        /*
         * First, look for one under a delegation that was locally issued
         * and just decrement the opencnt for it. Since all my Opens against
         * the server are DENY_NONE, I don't see a problem with hanging
         * onto them. (It is much easier to use one of the extant Opens
         * that I already have on the server when a Delegation is recalled
         * than to do fresh Opens.) Someday, I might need to rethink this, but.
         */
        dp = nfscl_finddeleg(clp, nfhp->nfh_fh, nfhp->nfh_len);
        if (dp != NULL) {
                LIST_FOREACH(owp, &dp->nfsdl_owner, nfsow_list) {
                        op = LIST_FIRST(&owp->nfsow_open);
                        if (op != NULL) {
                                /*
                                 * Since a delegation is for a file, there
                                 * should never be more than one open for
                                 * each openowner.
                                 */
                                if (LIST_NEXT(op, nfso_list) != NULL)
                                        panic("nfscdeleg opens");
                                if (notdecr && op->nfso_opencnt > 0) {
                                        notdecr = 0;
                                        op->nfso_opencnt--;
                                        break;
                                }
                        }
                }
        }

        /* Now process the opens against the server. */
        LIST_FOREACH(owp, &clp->nfsc_owner, nfsow_list) {
                LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                        if (op->nfso_fhlen == nfhp->nfh_len &&
                            !NFSBCMP(op->nfso_fh, nfhp->nfh_fh,
                            nfhp->nfh_len)) {
                                /* Found an open, decrement cnt if possible */
                                if (notdecr && op->nfso_opencnt > 0) {
                                        notdecr = 0;
                                        op->nfso_opencnt--;
                                }
                                /*
                                 * There are more opens, so just return.
                                 */
                                if (op->nfso_opencnt > 0) {
                                        NFSUNLOCKCLSTATE();
                                        return (0);
                                }
                        }
                }
        }
        NFSUNLOCKCLSTATE();
        if (notdecr)
                printf("nfscl: never fnd open\n");
        return (0);
}

APPLESTATIC int
nfscl_doclose(vnode_t vp, struct nfsclclient **clpp, NFSPROC_T *p)
{
        struct nfsclclient *clp;
        struct nfsclowner *owp, *nowp;
        struct nfsclopen *op;
        struct nfscldeleg *dp;
        struct nfsfh *nfhp;
        struct nfsclrecalllayout *recallp;
        int error;

        error = nfscl_getcl(vnode_mount(vp), NULL, NULL, 1, &clp);
        if (error)
                return (error);
        *clpp = clp;

        nfhp = VTONFS(vp)->n_fhp;
        recallp = malloc(sizeof(*recallp), M_NFSLAYRECALL, M_WAITOK);
        NFSLOCKCLSTATE();
        /*
         * First get rid of the local Open structures, which should be no
         * longer in use.
         */
        dp = nfscl_finddeleg(clp, nfhp->nfh_fh, nfhp->nfh_len);
        if (dp != NULL) {
                LIST_FOREACH_SAFE(owp, &dp->nfsdl_owner, nfsow_list, nowp) {
                        op = LIST_FIRST(&owp->nfsow_open);
                        if (op != NULL) {
                                KASSERT((op->nfso_opencnt == 0),
                                    ("nfscl: bad open cnt on deleg"));
                                nfscl_freeopen(op, 1);
                        }
                        nfscl_freeopenowner(owp, 1);
                }
        }

        /* Return any layouts marked return on close. */
        nfscl_retoncloselayout(vp, clp, nfhp->nfh_fh, nfhp->nfh_len, &recallp);

        /* Now process the opens against the server. */
lookformore:
        LIST_FOREACH(owp, &clp->nfsc_owner, nfsow_list) {
                op = LIST_FIRST(&owp->nfsow_open);
                while (op != NULL) {
                        if (op->nfso_fhlen == nfhp->nfh_len &&
                            !NFSBCMP(op->nfso_fh, nfhp->nfh_fh,
                            nfhp->nfh_len)) {
                                /* Found an open, close it. */
#ifdef DIAGNOSTIC
                                KASSERT((op->nfso_opencnt == 0),
                                    ("nfscl: bad open cnt on server (%d)",
                                     op->nfso_opencnt));
#endif
                                NFSUNLOCKCLSTATE();
                                nfsrpc_doclose(VFSTONFS(vnode_mount(vp)), op,
                                    p);
                                NFSLOCKCLSTATE();
                                goto lookformore;
                        }
                        op = LIST_NEXT(op, nfso_list);
                }
        }
        NFSUNLOCKCLSTATE();
        /*
         * recallp has been set NULL by nfscl_retoncloselayout() if it was
         * used by the function, but calling free() with a NULL pointer is ok.
         */
        free(recallp, M_NFSLAYRECALL);
        return (0);
}

/*
 * Return all delegations on this client.
 * (Must be called with client sleep lock.)
 */
static void
nfscl_delegreturnall(struct nfsclclient *clp, NFSPROC_T *p)
{
        struct nfscldeleg *dp, *ndp;
        struct ucred *cred;

        cred = newnfs_getcred();
        TAILQ_FOREACH_SAFE(dp, &clp->nfsc_deleg, nfsdl_list, ndp) {
                nfscl_cleandeleg(dp);
                (void) nfscl_trydelegreturn(dp, cred, clp->nfsc_nmp, p);
                nfscl_freedeleg(&clp->nfsc_deleg, dp);
        }
        NFSFREECRED(cred);
}

/*
 * Do a callback RPC.
 */
APPLESTATIC void
nfscl_docb(struct nfsrv_descript *nd, NFSPROC_T *p)
{
        int clist, gotseq_ok, i, j, k, op, rcalls;
        u_int32_t *tl;
        struct nfsclclient *clp;
        struct nfscldeleg *dp = NULL;
        int numops, taglen = -1, error = 0, trunc __unused;
        u_int32_t minorvers = 0, retops = 0, *retopsp = NULL, *repp, cbident;
        u_char tag[NFSV4_SMALLSTR + 1], *tagstr;
        vnode_t vp = NULL;
        struct nfsnode *np;
        struct vattr va;
        struct nfsfh *nfhp;
        mount_t mp;
        nfsattrbit_t attrbits, rattrbits;
        nfsv4stateid_t stateid;
        uint32_t seqid, slotid = 0, highslot, cachethis __unused;
        uint8_t sessionid[NFSX_V4SESSIONID];
        struct mbuf *rep;
        struct nfscllayout *lyp;
        uint64_t filesid[2], len, off;
        int changed, gotone, laytype, recalltype;
        uint32_t iomode;
        struct nfsclrecalllayout *recallp = NULL;
        struct nfsclsession *tsep;

        gotseq_ok = 0;
        nfsrvd_rephead(nd);
        NFSM_DISSECT(tl, u_int32_t *, NFSX_UNSIGNED);
        taglen = fxdr_unsigned(int, *tl);
        if (taglen < 0) {
                error = EBADRPC;
                goto nfsmout;
        }
        if (taglen <= NFSV4_SMALLSTR)
                tagstr = tag;
        else
                tagstr = malloc(taglen + 1, M_TEMP, M_WAITOK);
        error = nfsrv_mtostr(nd, tagstr, taglen);
        if (error) {
                if (taglen > NFSV4_SMALLSTR)
                        free(tagstr, M_TEMP);
                taglen = -1;
                goto nfsmout;
        }
        (void) nfsm_strtom(nd, tag, taglen);
        if (taglen > NFSV4_SMALLSTR) {
                free(tagstr, M_TEMP);
        }
        NFSM_BUILD(retopsp, u_int32_t *, NFSX_UNSIGNED);
        NFSM_DISSECT(tl, u_int32_t *, 3 * NFSX_UNSIGNED);
        minorvers = fxdr_unsigned(u_int32_t, *tl++);
        if (minorvers != NFSV4_MINORVERSION && minorvers != NFSV41_MINORVERSION)
                nd->nd_repstat = NFSERR_MINORVERMISMATCH;
        cbident = fxdr_unsigned(u_int32_t, *tl++);
        if (nd->nd_repstat)
                numops = 0;
        else
                numops = fxdr_unsigned(int, *tl);
        /*
         * Loop around doing the sub ops.
         */
        for (i = 0; i < numops; i++) {
                NFSM_DISSECT(tl, u_int32_t *, NFSX_UNSIGNED);
                NFSM_BUILD(repp, u_int32_t *, 2 * NFSX_UNSIGNED);
                *repp++ = *tl;
                op = fxdr_unsigned(int, *tl);
                if (op < NFSV4OP_CBGETATTR ||
                   (op > NFSV4OP_CBRECALL && minorvers == NFSV4_MINORVERSION) ||
                   (op > NFSV4OP_CBNOTIFYDEVID &&
                    minorvers == NFSV41_MINORVERSION)) {
                    nd->nd_repstat = NFSERR_OPILLEGAL;
                    *repp = nfscl_errmap(nd, minorvers);
                    retops++;
                    break;
                }
                nd->nd_procnum = op;
                if (op < NFSV41_CBNOPS)
                        nfsstatsv1.cbrpccnt[nd->nd_procnum]++;
                switch (op) {
                case NFSV4OP_CBGETATTR:
                        NFSCL_DEBUG(4, "cbgetattr\n");
                        mp = NULL;
                        vp = NULL;
                        error = nfsm_getfh(nd, &nfhp);
                        if (!error)
                                error = nfsrv_getattrbits(nd, &attrbits,
                                    NULL, NULL);
                        if (error == 0 && i == 0 &&
                            minorvers != NFSV4_MINORVERSION)
                                error = NFSERR_OPNOTINSESS;
                        if (!error) {
                                mp = nfscl_getmnt(minorvers, sessionid, cbident,
                                    &clp);
                                if (mp == NULL)
                                        error = NFSERR_SERVERFAULT;
                        }
                        if (!error) {
                                error = nfscl_ngetreopen(mp, nfhp->nfh_fh,
                                    nfhp->nfh_len, p, &np);
                                if (!error)
                                        vp = NFSTOV(np);
                        }
                        if (!error) {
                                NFSZERO_ATTRBIT(&rattrbits);
                                NFSLOCKCLSTATE();
                                dp = nfscl_finddeleg(clp, nfhp->nfh_fh,
                                    nfhp->nfh_len);
                                if (dp != NULL) {
                                        if (NFSISSET_ATTRBIT(&attrbits,
                                            NFSATTRBIT_SIZE)) {
                                                if (vp != NULL)
                                                        va.va_size = np->n_size;
                                                else
                                                        va.va_size =
                                                            dp->nfsdl_size;
                                                NFSSETBIT_ATTRBIT(&rattrbits,
                                                    NFSATTRBIT_SIZE);
                                        }
                                        if (NFSISSET_ATTRBIT(&attrbits,
                                            NFSATTRBIT_CHANGE)) {
                                                va.va_filerev =
                                                    dp->nfsdl_change;
                                                if (vp == NULL ||
                                                    (np->n_flag & NDELEGMOD))
                                                        va.va_filerev++;
                                                NFSSETBIT_ATTRBIT(&rattrbits,
                                                    NFSATTRBIT_CHANGE);
                                        }
                                } else
                                        error = NFSERR_SERVERFAULT;
                                NFSUNLOCKCLSTATE();
                        }
                        if (vp != NULL)
                                vrele(vp);
                        if (mp != NULL)
                                vfs_unbusy(mp);
                        if (nfhp != NULL)
                                free(nfhp, M_NFSFH);
                        if (!error)
                                (void) nfsv4_fillattr(nd, NULL, NULL, NULL, &va,
                                    NULL, 0, &rattrbits, NULL, p, 0, 0, 0, 0,
                                    (uint64_t)0, NULL);
                        break;
                case NFSV4OP_CBRECALL:
                        NFSCL_DEBUG(4, "cbrecall\n");
                        NFSM_DISSECT(tl, u_int32_t *, NFSX_STATEID +
                            NFSX_UNSIGNED);
                        stateid.seqid = *tl++;
                        NFSBCOPY((caddr_t)tl, (caddr_t)stateid.other,
                            NFSX_STATEIDOTHER);
                        tl += (NFSX_STATEIDOTHER / NFSX_UNSIGNED);
                        trunc = fxdr_unsigned(int, *tl);
                        error = nfsm_getfh(nd, &nfhp);
                        if (error == 0 && i == 0 &&
                            minorvers != NFSV4_MINORVERSION)
                                error = NFSERR_OPNOTINSESS;
                        if (!error) {
                                NFSLOCKCLSTATE();
                                if (minorvers == NFSV4_MINORVERSION)
                                        clp = nfscl_getclnt(cbident);
                                else
                                        clp = nfscl_getclntsess(sessionid);
                                if (clp != NULL) {
                                        dp = nfscl_finddeleg(clp, nfhp->nfh_fh,
                                            nfhp->nfh_len);
                                        if (dp != NULL && (dp->nfsdl_flags &
                                            NFSCLDL_DELEGRET) == 0) {
                                                dp->nfsdl_flags |=
                                                    NFSCLDL_RECALL;
                                                wakeup((caddr_t)clp);
                                        }
                                } else {
                                        error = NFSERR_SERVERFAULT;
                                }
                                NFSUNLOCKCLSTATE();
                        }
                        if (nfhp != NULL)
                                free(nfhp, M_NFSFH);
                        break;
                case NFSV4OP_CBLAYOUTRECALL:
                        NFSCL_DEBUG(4, "cblayrec\n");
                        nfhp = NULL;
                        NFSM_DISSECT(tl, uint32_t *, 4 * NFSX_UNSIGNED);
                        laytype = fxdr_unsigned(int, *tl++);
                        iomode = fxdr_unsigned(uint32_t, *tl++);
                        if (newnfs_true == *tl++)
                                changed = 1;
                        else
                                changed = 0;
                        recalltype = fxdr_unsigned(int, *tl);
                        NFSCL_DEBUG(4, "layt=%d iom=%d ch=%d rectyp=%d\n",
                            laytype, iomode, changed, recalltype);
                        recallp = malloc(sizeof(*recallp), M_NFSLAYRECALL,
                            M_WAITOK);
                        if (laytype != NFSLAYOUT_NFSV4_1_FILES &&
                            laytype != NFSLAYOUT_FLEXFILE)
                                error = NFSERR_NOMATCHLAYOUT;
                        else if (recalltype == NFSLAYOUTRETURN_FILE) {
                                error = nfsm_getfh(nd, &nfhp);
                                NFSCL_DEBUG(4, "retfile getfh=%d\n", error);
                                if (error != 0)
                                        goto nfsmout;
                                NFSM_DISSECT(tl, u_int32_t *, 2 * NFSX_HYPER +
                                    NFSX_STATEID);
                                off = fxdr_hyper(tl); tl += 2;
                                len = fxdr_hyper(tl); tl += 2;
                                stateid.seqid = fxdr_unsigned(uint32_t, *tl++);
                                NFSBCOPY(tl, stateid.other, NFSX_STATEIDOTHER);
                                if (minorvers == NFSV4_MINORVERSION)
                                        error = NFSERR_NOTSUPP;
                                else if (i == 0)
                                        error = NFSERR_OPNOTINSESS;
                                NFSCL_DEBUG(4, "off=%ju len=%ju sq=%u err=%d\n",
                                    (uintmax_t)off, (uintmax_t)len,
                                    stateid.seqid, error);
                                if (error == 0) {
                                        NFSLOCKCLSTATE();
                                        clp = nfscl_getclntsess(sessionid);
                                        NFSCL_DEBUG(4, "cbly clp=%p\n", clp);
                                        if (clp != NULL) {
                                                lyp = nfscl_findlayout(clp,
                                                    nfhp->nfh_fh,
                                                    nfhp->nfh_len);
                                                NFSCL_DEBUG(4, "cblyp=%p\n",
                                                    lyp);
                                                if (lyp != NULL &&
                                                    (lyp->nfsly_flags &
                                                     (NFSLY_FILES |
                                                      NFSLY_FLEXFILE)) != 0 &&
                                                    !NFSBCMP(stateid.other,
                                                    lyp->nfsly_stateid.other,
                                                    NFSX_STATEIDOTHER)) {
                                                        error =
                                                            nfscl_layoutrecall(
                                                            recalltype,
                                                            lyp, iomode, off,
                                                            len, stateid.seqid,
                                                            0, 0, NULL,
                                                            recallp);
                                                        recallp = NULL;
                                                        wakeup(clp);
                                                        NFSCL_DEBUG(4,
                                                            "aft layrcal=%d\n",
                                                            error);
                                                } else
                                                        error =
                                                          NFSERR_NOMATCHLAYOUT;
                                        } else
                                                error = NFSERR_NOMATCHLAYOUT;
                                        NFSUNLOCKCLSTATE();
                                }
                                free(nfhp, M_NFSFH);
                        } else if (recalltype == NFSLAYOUTRETURN_FSID) {
                                NFSM_DISSECT(tl, uint32_t *, 2 * NFSX_HYPER);
                                filesid[0] = fxdr_hyper(tl); tl += 2;
                                filesid[1] = fxdr_hyper(tl); tl += 2;
                                gotone = 0;
                                NFSLOCKCLSTATE();
                                clp = nfscl_getclntsess(sessionid);
                                if (clp != NULL) {
                                        TAILQ_FOREACH(lyp, &clp->nfsc_layout,
                                            nfsly_list) {
                                                if (lyp->nfsly_filesid[0] ==
                                                    filesid[0] &&
                                                    lyp->nfsly_filesid[1] ==
                                                    filesid[1]) {
                                                        error =
                                                            nfscl_layoutrecall(
                                                            recalltype,
                                                            lyp, iomode, 0,
                                                            UINT64_MAX,
                                                            lyp->nfsly_stateid.seqid,
                                                            0, 0, NULL,
                                                            recallp);
                                                        recallp = NULL;
                                                        gotone = 1;
                                                }
                                        }
                                        if (gotone != 0)
                                                wakeup(clp);
                                        else
                                                error = NFSERR_NOMATCHLAYOUT;
                                } else
                                        error = NFSERR_NOMATCHLAYOUT;
                                NFSUNLOCKCLSTATE();
                        } else if (recalltype == NFSLAYOUTRETURN_ALL) {
                                gotone = 0;
                                NFSLOCKCLSTATE();
                                clp = nfscl_getclntsess(sessionid);
                                if (clp != NULL) {
                                        TAILQ_FOREACH(lyp, &clp->nfsc_layout,
                                            nfsly_list) {
                                                error = nfscl_layoutrecall(
                                                    recalltype, lyp, iomode, 0,
                                                    UINT64_MAX,
                                                    lyp->nfsly_stateid.seqid,
                                                    0, 0, NULL, recallp);
                                                recallp = NULL;
                                                gotone = 1;
                                        }
                                        if (gotone != 0)
                                                wakeup(clp);
                                        else
                                                error = NFSERR_NOMATCHLAYOUT;
                                } else
                                        error = NFSERR_NOMATCHLAYOUT;
                                NFSUNLOCKCLSTATE();
                        } else
                                error = NFSERR_NOMATCHLAYOUT;
                        if (recallp != NULL) {
                                free(recallp, M_NFSLAYRECALL);
                                recallp = NULL;
                        }
                        break;
                case NFSV4OP_CBSEQUENCE:
                        NFSM_DISSECT(tl, uint32_t *, NFSX_V4SESSIONID +
                            5 * NFSX_UNSIGNED);
                        bcopy(tl, sessionid, NFSX_V4SESSIONID);
                        tl += NFSX_V4SESSIONID / NFSX_UNSIGNED;
                        seqid = fxdr_unsigned(uint32_t, *tl++);
                        slotid = fxdr_unsigned(uint32_t, *tl++);
                        highslot = fxdr_unsigned(uint32_t, *tl++);
                        cachethis = *tl++;
                        /* Throw away the referring call stuff. */
                        clist = fxdr_unsigned(int, *tl);
                        for (j = 0; j < clist; j++) {
                                NFSM_DISSECT(tl, uint32_t *, NFSX_V4SESSIONID +
                                    NFSX_UNSIGNED);
                                tl += NFSX_V4SESSIONID / NFSX_UNSIGNED;
                                rcalls = fxdr_unsigned(int, *tl);
                                for (k = 0; k < rcalls; k++) {
                                        NFSM_DISSECT(tl, uint32_t *,
                                            2 * NFSX_UNSIGNED);
                                }
                        }
                        NFSLOCKCLSTATE();
                        if (i == 0) {
                                clp = nfscl_getclntsess(sessionid);
                                if (clp == NULL)
                                        error = NFSERR_SERVERFAULT;
                        } else
                                error = NFSERR_SEQUENCEPOS;
                        if (error == 0) {
                                tsep = nfsmnt_mdssession(clp->nfsc_nmp);
                                error = nfsv4_seqsession(seqid, slotid,
                                    highslot, tsep->nfsess_cbslots, &rep,
                                    tsep->nfsess_backslots);
                        }
                        NFSUNLOCKCLSTATE();
                        if (error == 0 || error == NFSERR_REPLYFROMCACHE) {
                                gotseq_ok = 1;
                                if (rep != NULL) {
                                        /*
                                         * Handle a reply for a retried
                                         * callback.  The reply will be
                                         * re-inserted in the session cache
                                         * by the nfsv4_seqsess_cacherep() call
                                         * after out:
                                         */
                                        KASSERT(error == NFSERR_REPLYFROMCACHE,
                                            ("cbsequence: non-NULL rep"));
                                        NFSCL_DEBUG(4, "Got cbretry\n");
                                        m_freem(nd->nd_mreq);
                                        nd->nd_mreq = rep;
                                        rep = NULL;
                                        goto out;
                                }
                                NFSM_BUILD(tl, uint32_t *,
                                    NFSX_V4SESSIONID + 4 * NFSX_UNSIGNED);
                                bcopy(sessionid, tl, NFSX_V4SESSIONID);
                                tl += NFSX_V4SESSIONID / NFSX_UNSIGNED;
                                *tl++ = txdr_unsigned(seqid);
                                *tl++ = txdr_unsigned(slotid);
                                *tl++ = txdr_unsigned(NFSV4_CBSLOTS - 1);
                                *tl = txdr_unsigned(NFSV4_CBSLOTS - 1);
                        }
                        break;
                default:
                        if (i == 0 && minorvers == NFSV41_MINORVERSION)
                                error = NFSERR_OPNOTINSESS;
                        else {
                                NFSCL_DEBUG(1, "unsupp callback %d\n", op);
                                error = NFSERR_NOTSUPP;
                        }
                        break;
                }
                if (error) {
                        if (error == EBADRPC || error == NFSERR_BADXDR) {
                                nd->nd_repstat = NFSERR_BADXDR;
                        } else {
                                nd->nd_repstat = error;
                        }
                        error = 0;
                }
                retops++;
                if (nd->nd_repstat) {
                        *repp = nfscl_errmap(nd, minorvers);
                        break;
                } else
                        *repp = 0;      /* NFS4_OK */
        }
nfsmout:
        if (recallp != NULL)
                free(recallp, M_NFSLAYRECALL);
        if (error) {
                if (error == EBADRPC || error == NFSERR_BADXDR)
                        nd->nd_repstat = NFSERR_BADXDR;
                else
                        printf("nfsv4 comperr1=%d\n", error);
        }
        if (taglen == -1) {
                NFSM_BUILD(tl, u_int32_t *, 2 * NFSX_UNSIGNED);
                *tl++ = 0;
                *tl = 0;
        } else {
                *retopsp = txdr_unsigned(retops);
        }
        *nd->nd_errp = nfscl_errmap(nd, minorvers);
out:
        if (gotseq_ok != 0) {
                rep = m_copym(nd->nd_mreq, 0, M_COPYALL, M_WAITOK);
                NFSLOCKCLSTATE();
                clp = nfscl_getclntsess(sessionid);
                if (clp != NULL) {
                        tsep = nfsmnt_mdssession(clp->nfsc_nmp);
                        nfsv4_seqsess_cacherep(slotid, tsep->nfsess_cbslots,
                            NFSERR_OK, &rep);
                        NFSUNLOCKCLSTATE();
                } else {
                        NFSUNLOCKCLSTATE();
                        m_freem(rep);
                }
        }
}

/*
 * Generate the next cbident value. Basically just increment a static value
 * and then check that it isn't already in the list, if it has wrapped around.
 */
static u_int32_t
nfscl_nextcbident(void)
{
        struct nfsclclient *clp;
        int matched;
        static u_int32_t nextcbident = 0;
        static int haswrapped = 0;

        nextcbident++;
        if (nextcbident == 0)
                haswrapped = 1;
        if (haswrapped) {
                /*
                 * Search the clientid list for one already using this cbident.
                 */
                do {
                        matched = 0;
                        NFSLOCKCLSTATE();
                        LIST_FOREACH(clp, &nfsclhead, nfsc_list) {
                                if (clp->nfsc_cbident == nextcbident) {
                                        matched = 1;
                                        break;
                                }
                        }
                        NFSUNLOCKCLSTATE();
                        if (matched == 1)
                                nextcbident++;
                } while (matched);
        }
        return (nextcbident);
}

/*
 * Get the mount point related to a given cbident or session and busy it.
 */
static mount_t
nfscl_getmnt(int minorvers, uint8_t *sessionid, u_int32_t cbident,
    struct nfsclclient **clpp)
{
        struct nfsclclient *clp;
        mount_t mp;
        int error;
        struct nfsclsession *tsep;

        *clpp = NULL;
        NFSLOCKCLSTATE();
        LIST_FOREACH(clp, &nfsclhead, nfsc_list) {
                tsep = nfsmnt_mdssession(clp->nfsc_nmp);
                if (minorvers == NFSV4_MINORVERSION) {
                        if (clp->nfsc_cbident == cbident)
                                break;
                } else if (!NFSBCMP(tsep->nfsess_sessionid, sessionid,
                    NFSX_V4SESSIONID))
                        break;
        }
        if (clp == NULL) {
                NFSUNLOCKCLSTATE();
                return (NULL);
        }
        mp = clp->nfsc_nmp->nm_mountp;
        vfs_ref(mp);
        NFSUNLOCKCLSTATE();
        error = vfs_busy(mp, 0);
        vfs_rel(mp);
        if (error != 0)
                return (NULL);
        *clpp = clp;
        return (mp);
}

/*
 * Get the clientid pointer related to a given cbident.
 */
static struct nfsclclient *
nfscl_getclnt(u_int32_t cbident)
{
        struct nfsclclient *clp;

        LIST_FOREACH(clp, &nfsclhead, nfsc_list)
                if (clp->nfsc_cbident == cbident)
                        break;
        return (clp);
}

/*
 * Get the clientid pointer related to a given sessionid.
 */
static struct nfsclclient *
nfscl_getclntsess(uint8_t *sessionid)
{
        struct nfsclclient *clp;
        struct nfsclsession *tsep;

        LIST_FOREACH(clp, &nfsclhead, nfsc_list) {
                tsep = nfsmnt_mdssession(clp->nfsc_nmp);
                if (!NFSBCMP(tsep->nfsess_sessionid, sessionid,
                    NFSX_V4SESSIONID))
                        break;
        }
        return (clp);
}

/*
 * Search for a lock conflict locally on the client. A conflict occurs if
 * - not same owner and overlapping byte range and at least one of them is
 *   a write lock or this is an unlock.
 */
static int
nfscl_localconflict(struct nfsclclient *clp, u_int8_t *fhp, int fhlen,
    struct nfscllock *nlop, u_int8_t *own, struct nfscldeleg *dp,
    struct nfscllock **lopp)
{
        struct nfsclowner *owp;
        struct nfsclopen *op;
        int ret;

        if (dp != NULL) {
                ret = nfscl_checkconflict(&dp->nfsdl_lock, nlop, own, lopp);
                if (ret)
                        return (ret);
        }
        LIST_FOREACH(owp, &clp->nfsc_owner, nfsow_list) {
                LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                        if (op->nfso_fhlen == fhlen &&
                            !NFSBCMP(op->nfso_fh, fhp, fhlen)) {
                                ret = nfscl_checkconflict(&op->nfso_lock, nlop,
                                    own, lopp);
                                if (ret)
                                        return (ret);
                        }
                }
        }
        return (0);
}

static int
nfscl_checkconflict(struct nfscllockownerhead *lhp, struct nfscllock *nlop,
    u_int8_t *own, struct nfscllock **lopp)
{
        struct nfscllockowner *lp;
        struct nfscllock *lop;

        LIST_FOREACH(lp, lhp, nfsl_list) {
                if (NFSBCMP(lp->nfsl_owner, own, NFSV4CL_LOCKNAMELEN)) {
                        LIST_FOREACH(lop, &lp->nfsl_lock, nfslo_list) {
                                if (lop->nfslo_first >= nlop->nfslo_end)
                                        break;
                                if (lop->nfslo_end <= nlop->nfslo_first)
                                        continue;
                                if (lop->nfslo_type == F_WRLCK ||
                                    nlop->nfslo_type == F_WRLCK ||
                                    nlop->nfslo_type == F_UNLCK) {
                                        if (lopp != NULL)
                                                *lopp = lop;
                                        return (NFSERR_DENIED);
                                }
                        }
                }
        }
        return (0);
}

/*
 * Check for a local conflicting lock.
 */
APPLESTATIC int
nfscl_lockt(vnode_t vp, struct nfsclclient *clp, u_int64_t off,
    u_int64_t len, struct flock *fl, NFSPROC_T *p, void *id, int flags)
{
        struct nfscllock *lop, nlck;
        struct nfscldeleg *dp;
        struct nfsnode *np;
        u_int8_t own[NFSV4CL_LOCKNAMELEN];
        int error;

        nlck.nfslo_type = fl->l_type;
        nlck.nfslo_first = off;
        if (len == NFS64BITSSET) {
                nlck.nfslo_end = NFS64BITSSET;
        } else {
                nlck.nfslo_end = off + len;
                if (nlck.nfslo_end <= nlck.nfslo_first)
                        return (NFSERR_INVAL);
        }
        np = VTONFS(vp);
        nfscl_filllockowner(id, own, flags);
        NFSLOCKCLSTATE();
        dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh, np->n_fhp->nfh_len);
        error = nfscl_localconflict(clp, np->n_fhp->nfh_fh, np->n_fhp->nfh_len,
            &nlck, own, dp, &lop);
        if (error != 0) {
                fl->l_whence = SEEK_SET;
                fl->l_start = lop->nfslo_first;
                if (lop->nfslo_end == NFS64BITSSET)
                        fl->l_len = 0;
                else
                        fl->l_len = lop->nfslo_end - lop->nfslo_first;
                fl->l_pid = (pid_t)0;
                fl->l_type = lop->nfslo_type;
                error = -1;                     /* no RPC required */
        } else if (dp != NULL && ((dp->nfsdl_flags & NFSCLDL_WRITE) ||
            fl->l_type == F_RDLCK)) {
                /*
                 * The delegation ensures that there isn't a conflicting
                 * lock on the server, so return -1 to indicate an RPC
                 * isn't required.
                 */
                fl->l_type = F_UNLCK;
                error = -1;
        }
        NFSUNLOCKCLSTATE();
        return (error);
}

/*
 * Handle Recall of a delegation.
 * The clp must be exclusive locked when this is called.
 */
static int
nfscl_recalldeleg(struct nfsclclient *clp, struct nfsmount *nmp,
    struct nfscldeleg *dp, vnode_t vp, struct ucred *cred, NFSPROC_T *p,
    int called_from_renewthread)
{
        struct nfsclowner *owp, *lowp, *nowp;
        struct nfsclopen *op, *lop;
        struct nfscllockowner *lp;
        struct nfscllock *lckp;
        struct nfsnode *np;
        int error = 0, ret, gotvp = 0;

        if (vp == NULL) {
                /*
                 * First, get a vnode for the file. This is needed to do RPCs.
                 */
                ret = nfscl_ngetreopen(nmp->nm_mountp, dp->nfsdl_fh,
                    dp->nfsdl_fhlen, p, &np);
                if (ret) {
                        /*
                         * File isn't open, so nothing to move over to the
                         * server.
                         */
                        return (0);
                }
                vp = NFSTOV(np);
                gotvp = 1;
        } else {
                np = VTONFS(vp);
        }
        dp->nfsdl_flags &= ~NFSCLDL_MODTIMESET;

        /*
         * Ok, if it's a write delegation, flush data to the server, so
         * that close/open consistency is retained.
         */
        ret = 0;
        NFSLOCKNODE(np);
        if ((dp->nfsdl_flags & NFSCLDL_WRITE) && (np->n_flag & NMODIFIED)) {
                np->n_flag |= NDELEGRECALL;
                NFSUNLOCKNODE(np);
                ret = ncl_flush(vp, MNT_WAIT, p, 1, called_from_renewthread);
                NFSLOCKNODE(np);
                np->n_flag &= ~NDELEGRECALL;
        }
        NFSINVALATTRCACHE(np);
        NFSUNLOCKNODE(np);
        if (ret == EIO && called_from_renewthread != 0) {
                /*
                 * If the flush failed with EIO for the renew thread,
                 * return now, so that the dirty buffer will be flushed
                 * later.
                 */
                if (gotvp != 0)
                        vrele(vp);
                return (ret);
        }

        /*
         * Now, for each openowner with opens issued locally, move them
         * over to state against the server.
         */
        LIST_FOREACH(lowp, &dp->nfsdl_owner, nfsow_list) {
                lop = LIST_FIRST(&lowp->nfsow_open);
                if (lop != NULL) {
                        if (LIST_NEXT(lop, nfso_list) != NULL)
                                panic("nfsdlg mult opens");
                        /*
                         * Look for the same openowner against the server.
                         */
                        LIST_FOREACH(owp, &clp->nfsc_owner, nfsow_list) {
                                if (!NFSBCMP(lowp->nfsow_owner,
                                    owp->nfsow_owner, NFSV4CL_LOCKNAMELEN)) {
                                        newnfs_copycred(&dp->nfsdl_cred, cred);
                                        ret = nfscl_moveopen(vp, clp, nmp, lop,
                                            owp, dp, cred, p);
                                        if (ret == NFSERR_STALECLIENTID ||
                                            ret == NFSERR_STALEDONTRECOVER ||
                                            ret == NFSERR_BADSESSION) {
                                                if (gotvp)
                                                        vrele(vp);
                                                return (ret);
                                        }
                                        if (ret) {
                                                nfscl_freeopen(lop, 1);
                                                if (!error)
                                                        error = ret;
                                        }
                                        break;
                                }
                        }

                        /*
                         * If no openowner found, create one and get an open
                         * for it.
                         */
                        if (owp == NULL) {
                                nowp = malloc(
                                    sizeof (struct nfsclowner), M_NFSCLOWNER,
                                    M_WAITOK);
                                nfscl_newopen(clp, NULL, &owp, &nowp, &op, 
                                    NULL, lowp->nfsow_owner, dp->nfsdl_fh,
                                    dp->nfsdl_fhlen, NULL, NULL);
                                newnfs_copycred(&dp->nfsdl_cred, cred);
                                ret = nfscl_moveopen(vp, clp, nmp, lop,
                                    owp, dp, cred, p);
                                if (ret) {
                                        nfscl_freeopenowner(owp, 0);
                                        if (ret == NFSERR_STALECLIENTID ||
                                            ret == NFSERR_STALEDONTRECOVER ||
                                            ret == NFSERR_BADSESSION) {
                                                if (gotvp)
                                                        vrele(vp);
                                                return (ret);
                                        }
                                        if (ret) {
                                                nfscl_freeopen(lop, 1);
                                                if (!error)
                                                        error = ret;
                                        }
                                }
                        }
                }
        }

        /*
         * Now, get byte range locks for any locks done locally.
         */
        LIST_FOREACH(lp, &dp->nfsdl_lock, nfsl_list) {
                LIST_FOREACH(lckp, &lp->nfsl_lock, nfslo_list) {
                        newnfs_copycred(&dp->nfsdl_cred, cred);
                        ret = nfscl_relock(vp, clp, nmp, lp, lckp, cred, p);
                        if (ret == NFSERR_STALESTATEID ||
                            ret == NFSERR_STALEDONTRECOVER ||
                            ret == NFSERR_STALECLIENTID ||
                            ret == NFSERR_BADSESSION) {
                                if (gotvp)
                                        vrele(vp);
                                return (ret);
                        }
                        if (ret && !error)
                                error = ret;
                }
        }
        if (gotvp)
                vrele(vp);
        return (error);
}

/*
 * Move a locally issued open over to an owner on the state list.
 * SIDE EFFECT: If it needs to sleep (do an rpc), it unlocks clstate and
 * returns with it unlocked.
 */
static int
nfscl_moveopen(vnode_t vp, struct nfsclclient *clp, struct nfsmount *nmp,
    struct nfsclopen *lop, struct nfsclowner *owp, struct nfscldeleg *dp,
    struct ucred *cred, NFSPROC_T *p)
{
        struct nfsclopen *op, *nop;
        struct nfscldeleg *ndp;
        struct nfsnode *np;
        int error = 0, newone;

        /*
         * First, look for an appropriate open, If found, just increment the
         * opencnt in it.
         */
        LIST_FOREACH(op, &owp->nfsow_open, nfso_list) {
                if ((op->nfso_mode & lop->nfso_mode) == lop->nfso_mode &&
                    op->nfso_fhlen == lop->nfso_fhlen &&
                    !NFSBCMP(op->nfso_fh, lop->nfso_fh, op->nfso_fhlen)) {
                        op->nfso_opencnt += lop->nfso_opencnt;
                        nfscl_freeopen(lop, 1);
                        return (0);
                }
        }

        /* No appropriate open, so we have to do one against the server. */
        np = VTONFS(vp);
        nop = malloc(sizeof (struct nfsclopen) +
            lop->nfso_fhlen - 1, M_NFSCLOPEN, M_WAITOK);
        newone = 0;
        nfscl_newopen(clp, NULL, &owp, NULL, &op, &nop, owp->nfsow_owner,
            lop->nfso_fh, lop->nfso_fhlen, cred, &newone);
        ndp = dp;
        error = nfscl_tryopen(nmp, vp, np->n_v4->n4_data, np->n_v4->n4_fhlen,
            lop->nfso_fh, lop->nfso_fhlen, lop->nfso_mode, op,
            NFS4NODENAME(np->n_v4), np->n_v4->n4_namelen, &ndp, 0, 0, cred, p);
        if (error) {
                if (newone)
                        nfscl_freeopen(op, 0);
        } else {
                op->nfso_mode |= lop->nfso_mode;
                op->nfso_opencnt += lop->nfso_opencnt;
                nfscl_freeopen(lop, 1);
        }
        if (nop != NULL)
                free(nop, M_NFSCLOPEN);
        if (ndp != NULL) {
                /*
                 * What should I do with the returned delegation, since the
                 * delegation is being recalled? For now, just printf and
                 * through it away.
                 */
                printf("Moveopen returned deleg\n");
                free(ndp, M_NFSCLDELEG);
        }
        return (error);
}

/*
 * Recall all delegations on this client.
 */
static void
nfscl_totalrecall(struct nfsclclient *clp)
{
        struct nfscldeleg *dp;

        TAILQ_FOREACH(dp, &clp->nfsc_deleg, nfsdl_list) {
                if ((dp->nfsdl_flags & NFSCLDL_DELEGRET) == 0)
                        dp->nfsdl_flags |= NFSCLDL_RECALL;
        }
}

/*
 * Relock byte ranges. Called for delegation recall and state expiry.
 */
static int
nfscl_relock(vnode_t vp, struct nfsclclient *clp, struct nfsmount *nmp,
    struct nfscllockowner *lp, struct nfscllock *lop, struct ucred *cred,
    NFSPROC_T *p)
{
        struct nfscllockowner *nlp;
        struct nfsfh *nfhp;
        u_int64_t off, len;
        int error, newone, donelocally;

        off = lop->nfslo_first;
        len = lop->nfslo_end - lop->nfslo_first;
        error = nfscl_getbytelock(vp, off, len, lop->nfslo_type, cred, p,
            clp, 1, NULL, lp->nfsl_lockflags, lp->nfsl_owner,
            lp->nfsl_openowner, &nlp, &newone, &donelocally);
        if (error || donelocally)
                return (error);
        nfhp = VTONFS(vp)->n_fhp;
        error = nfscl_trylock(nmp, vp, nfhp->nfh_fh,
            nfhp->nfh_len, nlp, newone, 0, off,
            len, lop->nfslo_type, cred, p);
        if (error)
                nfscl_freelockowner(nlp, 0);
        return (error);
}

/*
 * Called to re-open a file. Basically get a vnode for the file handle
 * and then call nfsrpc_openrpc() to do the rest.
 */
static int
nfsrpc_reopen(struct nfsmount *nmp, u_int8_t *fhp, int fhlen,
    u_int32_t mode, struct nfsclopen *op, struct nfscldeleg **dpp,
    struct ucred *cred, NFSPROC_T *p)
{
        struct nfsnode *np;
        vnode_t vp;
        int error;

        error = nfscl_ngetreopen(nmp->nm_mountp, fhp, fhlen, p, &np);
        if (error)
                return (error);
        vp = NFSTOV(np);
        if (np->n_v4 != NULL) {
                error = nfscl_tryopen(nmp, vp, np->n_v4->n4_data,
                    np->n_v4->n4_fhlen, fhp, fhlen, mode, op,
                    NFS4NODENAME(np->n_v4), np->n_v4->n4_namelen, dpp, 0, 0,
                    cred, p);
        } else {
                error = EINVAL;
        }
        vrele(vp);
        return (error);
}

/*
 * Try an open against the server. Just call nfsrpc_openrpc(), retrying while
 * NFSERR_DELAY. Also, try system credentials, if the passed in credentials
 * fail.
 */
static int
nfscl_tryopen(struct nfsmount *nmp, vnode_t vp, u_int8_t *fhp, int fhlen,
    u_int8_t *newfhp, int newfhlen, u_int32_t mode, struct nfsclopen *op,
    u_int8_t *name, int namelen, struct nfscldeleg **ndpp,
    int reclaim, u_int32_t delegtype, struct ucred *cred, NFSPROC_T *p)
{
        int error;

        do {
                error = nfsrpc_openrpc(nmp, vp, fhp, fhlen, newfhp, newfhlen,
                    mode, op, name, namelen, ndpp, reclaim, delegtype, cred, p,
                    0, 0);
                if (error == NFSERR_DELAY)
                        (void) nfs_catnap(PZERO, error, "nfstryop");
        } while (error == NFSERR_DELAY);
        if (error == EAUTH || error == EACCES) {
                /* Try again using system credentials */
                newnfs_setroot(cred);
                do {
                    error = nfsrpc_openrpc(nmp, vp, fhp, fhlen, newfhp,
                        newfhlen, mode, op, name, namelen, ndpp, reclaim,
                        delegtype, cred, p, 1, 0);
                    if (error == NFSERR_DELAY)
                        (void) nfs_catnap(PZERO, error, "nfstryop");
                } while (error == NFSERR_DELAY);
        }
        return (error);
}

/*
 * Try a byte range lock. Just loop on nfsrpc_lock() while it returns
 * NFSERR_DELAY. Also, retry with system credentials, if the provided
 * cred don't work.
 */
static int
nfscl_trylock(struct nfsmount *nmp, vnode_t vp, u_int8_t *fhp,
    int fhlen, struct nfscllockowner *nlp, int newone, int reclaim,
    u_int64_t off, u_int64_t len, short type, struct ucred *cred, NFSPROC_T *p)
{
        struct nfsrv_descript nfsd, *nd = &nfsd;
        int error;

        do {
                error = nfsrpc_lock(nd, nmp, vp, fhp, fhlen, nlp, newone,
                    reclaim, off, len, type, cred, p, 0);
                if (!error && nd->nd_repstat == NFSERR_DELAY)
                        (void) nfs_catnap(PZERO, (int)nd->nd_repstat,
                            "nfstrylck");
        } while (!error && nd->nd_repstat == NFSERR_DELAY);
        if (!error)
                error = nd->nd_repstat;
        if (error == EAUTH || error == EACCES) {
                /* Try again using root credentials */
                newnfs_setroot(cred);
                do {
                        error = nfsrpc_lock(nd, nmp, vp, fhp, fhlen, nlp,
                            newone, reclaim, off, len, type, cred, p, 1);
                        if (!error && nd->nd_repstat == NFSERR_DELAY)
                                (void) nfs_catnap(PZERO, (int)nd->nd_repstat,
                                    "nfstrylck");
                } while (!error && nd->nd_repstat == NFSERR_DELAY);
                if (!error)
                        error = nd->nd_repstat;
        }
        return (error);
}

/*
 * Try a delegreturn against the server. Just call nfsrpc_delegreturn(),
 * retrying while NFSERR_DELAY. Also, try system credentials, if the passed in
 * credentials fail.
 */
static int
nfscl_trydelegreturn(struct nfscldeleg *dp, struct ucred *cred,
    struct nfsmount *nmp, NFSPROC_T *p)
{
        int error;

        do {
                error = nfsrpc_delegreturn(dp, cred, nmp, p, 0);
                if (error == NFSERR_DELAY)
                        (void) nfs_catnap(PZERO, error, "nfstrydp");
        } while (error == NFSERR_DELAY);
        if (error == EAUTH || error == EACCES) {
                /* Try again using system credentials */
                newnfs_setroot(cred);
                do {
                        error = nfsrpc_delegreturn(dp, cred, nmp, p, 1);
                        if (error == NFSERR_DELAY)
                                (void) nfs_catnap(PZERO, error, "nfstrydp");
                } while (error == NFSERR_DELAY);
        }
        return (error);
}

/*
 * Try a close against the server. Just call nfsrpc_closerpc(),
 * retrying while NFSERR_DELAY. Also, try system credentials, if the passed in
 * credentials fail.
 */
APPLESTATIC int
nfscl_tryclose(struct nfsclopen *op, struct ucred *cred,
    struct nfsmount *nmp, NFSPROC_T *p)
{
        struct nfsrv_descript nfsd, *nd = &nfsd;
        int error;

        do {
                error = nfsrpc_closerpc(nd, nmp, op, cred, p, 0);
                if (error == NFSERR_DELAY)
                        (void) nfs_catnap(PZERO, error, "nfstrycl");
        } while (error == NFSERR_DELAY);
        if (error == EAUTH || error == EACCES) {
                /* Try again using system credentials */
                newnfs_setroot(cred);
                do {
                        error = nfsrpc_closerpc(nd, nmp, op, cred, p, 1);
                        if (error == NFSERR_DELAY)
                                (void) nfs_catnap(PZERO, error, "nfstrycl");
                } while (error == NFSERR_DELAY);
        }
        return (error);
}

/*
 * Decide if a delegation on a file permits close without flushing writes
 * to the server. This might be a big performance win in some environments.
 * (Not useful until the client does caching on local stable storage.)
 */
APPLESTATIC int
nfscl_mustflush(vnode_t vp)
{
        struct nfsclclient *clp;
        struct nfscldeleg *dp;
        struct nfsnode *np;
        struct nfsmount *nmp;

        np = VTONFS(vp);
        nmp = VFSTONFS(vnode_mount(vp));
        if (!NFSHASNFSV4(nmp))
                return (1);
        NFSLOCKCLSTATE();
        clp = nfscl_findcl(nmp);
        if (clp == NULL) {
                NFSUNLOCKCLSTATE();
                return (1);
        }
        dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh, np->n_fhp->nfh_len);
        if (dp != NULL && (dp->nfsdl_flags &
            (NFSCLDL_WRITE | NFSCLDL_RECALL | NFSCLDL_DELEGRET)) ==
             NFSCLDL_WRITE &&
            (dp->nfsdl_sizelimit >= np->n_size ||
             !NFSHASSTRICT3530(nmp))) {
                NFSUNLOCKCLSTATE();
                return (0);
        }
        NFSUNLOCKCLSTATE();
        return (1);
}

/*
 * See if a (write) delegation exists for this file.
 */
APPLESTATIC int
nfscl_nodeleg(vnode_t vp, int writedeleg)
{
        struct nfsclclient *clp;
        struct nfscldeleg *dp;
        struct nfsnode *np;
        struct nfsmount *nmp;

        np = VTONFS(vp);
        nmp = VFSTONFS(vnode_mount(vp));
        if (!NFSHASNFSV4(nmp))
                return (1);
        NFSLOCKCLSTATE();
        clp = nfscl_findcl(nmp);
        if (clp == NULL) {
                NFSUNLOCKCLSTATE();
                return (1);
        }
        dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh, np->n_fhp->nfh_len);
        if (dp != NULL &&
            (dp->nfsdl_flags & (NFSCLDL_RECALL | NFSCLDL_DELEGRET)) == 0 &&
            (writedeleg == 0 || (dp->nfsdl_flags & NFSCLDL_WRITE) ==
             NFSCLDL_WRITE)) {
                NFSUNLOCKCLSTATE();
                return (0);
        }
        NFSUNLOCKCLSTATE();
        return (1);
}

/*
 * Look for an associated delegation that should be DelegReturned.
 */
APPLESTATIC int
nfscl_removedeleg(vnode_t vp, NFSPROC_T *p, nfsv4stateid_t *stp)
{
        struct nfsclclient *clp;
        struct nfscldeleg *dp;
        struct nfsclowner *owp;
        struct nfscllockowner *lp;
        struct nfsmount *nmp;
        struct ucred *cred;
        struct nfsnode *np;
        int igotlock = 0, triedrecall = 0, needsrecall, retcnt = 0, islept;

        nmp = VFSTONFS(vnode_mount(vp));
        np = VTONFS(vp);
        NFSLOCKCLSTATE();
        /*
         * Loop around waiting for:
         * - outstanding I/O operations on delegations to complete
         * - for a delegation on vp that has state, lock the client and
         *   do a recall
         * - return delegation with no state
         */
        while (1) {
                clp = nfscl_findcl(nmp);
                if (clp == NULL) {
                        NFSUNLOCKCLSTATE();
                        return (retcnt);
                }
                dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh,
                    np->n_fhp->nfh_len);
                if (dp != NULL) {
                    /*
                     * Wait for outstanding I/O ops to be done.
                     */
                    if (dp->nfsdl_rwlock.nfslock_usecnt > 0) {
                        if (igotlock) {
                            nfsv4_unlock(&clp->nfsc_lock, 0);
                            igotlock = 0;
                        }
                        dp->nfsdl_rwlock.nfslock_lock |= NFSV4LOCK_WANTED;
                        (void) nfsmsleep(&dp->nfsdl_rwlock,
                            NFSCLSTATEMUTEXPTR, PZERO, "nfscld", NULL);
                        continue;
                    }
                    needsrecall = 0;
                    LIST_FOREACH(owp, &dp->nfsdl_owner, nfsow_list) {
                        if (!LIST_EMPTY(&owp->nfsow_open)) {
                            needsrecall = 1;
                            break;
                        }
                    }
                    if (!needsrecall) {
                        LIST_FOREACH(lp, &dp->nfsdl_lock, nfsl_list) {
                            if (!LIST_EMPTY(&lp->nfsl_lock)) {
                                needsrecall = 1;
                                break;
                            }
                        }
                    }
                    if (needsrecall && !triedrecall) {
                        dp->nfsdl_flags |= NFSCLDL_DELEGRET;
                        islept = 0;
                        while (!igotlock) {
                            igotlock = nfsv4_lock(&clp->nfsc_lock, 1,
                                &islept, NFSCLSTATEMUTEXPTR, NULL);
                            if (islept)
                                break;
                        }
                        if (islept)
                            continue;
                        NFSUNLOCKCLSTATE();
                        cred = newnfs_getcred();
                        newnfs_copycred(&dp->nfsdl_cred, cred);
                        (void) nfscl_recalldeleg(clp, nmp, dp, vp, cred, p, 0);
                        NFSFREECRED(cred);
                        triedrecall = 1;
                        NFSLOCKCLSTATE();
                        nfsv4_unlock(&clp->nfsc_lock, 0);
                        igotlock = 0;
                        continue;
                    }
                    *stp = dp->nfsdl_stateid;
                    retcnt = 1;
                    nfscl_cleandeleg(dp);
                    nfscl_freedeleg(&clp->nfsc_deleg, dp);
                }
                if (igotlock)
                    nfsv4_unlock(&clp->nfsc_lock, 0);
                NFSUNLOCKCLSTATE();
                return (retcnt);
        }
}

/*
 * Look for associated delegation(s) that should be DelegReturned.
 */
APPLESTATIC int
nfscl_renamedeleg(vnode_t fvp, nfsv4stateid_t *fstp, int *gotfdp, vnode_t tvp,
    nfsv4stateid_t *tstp, int *gottdp, NFSPROC_T *p)
{
        struct nfsclclient *clp;
        struct nfscldeleg *dp;
        struct nfsclowner *owp;
        struct nfscllockowner *lp;
        struct nfsmount *nmp;
        struct ucred *cred;
        struct nfsnode *np;
        int igotlock = 0, triedrecall = 0, needsrecall, retcnt = 0, islept;

        nmp = VFSTONFS(vnode_mount(fvp));
        *gotfdp = 0;
        *gottdp = 0;
        NFSLOCKCLSTATE();
        /*
         * Loop around waiting for:
         * - outstanding I/O operations on delegations to complete
         * - for a delegation on fvp that has state, lock the client and
         *   do a recall
         * - return delegation(s) with no state.
         */
        while (1) {
                clp = nfscl_findcl(nmp);
                if (clp == NULL) {
                        NFSUNLOCKCLSTATE();
                        return (retcnt);
                }
                np = VTONFS(fvp);
                dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh,
                    np->n_fhp->nfh_len);
                if (dp != NULL && *gotfdp == 0) {
                    /*
                     * Wait for outstanding I/O ops to be done.
                     */
                    if (dp->nfsdl_rwlock.nfslock_usecnt > 0) {
                        if (igotlock) {
                            nfsv4_unlock(&clp->nfsc_lock, 0);
                            igotlock = 0;
                        }
                        dp->nfsdl_rwlock.nfslock_lock |= NFSV4LOCK_WANTED;
                        (void) nfsmsleep(&dp->nfsdl_rwlock,
                            NFSCLSTATEMUTEXPTR, PZERO, "nfscld", NULL);
                        continue;
                    }
                    needsrecall = 0;
                    LIST_FOREACH(owp, &dp->nfsdl_owner, nfsow_list) {
                        if (!LIST_EMPTY(&owp->nfsow_open)) {
                            needsrecall = 1;
                            break;
                        }
                    }
                    if (!needsrecall) {
                        LIST_FOREACH(lp, &dp->nfsdl_lock, nfsl_list) {
                            if (!LIST_EMPTY(&lp->nfsl_lock)) {
                                needsrecall = 1;
                                break;
                            }
                        }
                    }
                    if (needsrecall && !triedrecall) {
                        dp->nfsdl_flags |= NFSCLDL_DELEGRET;
                        islept = 0;
                        while (!igotlock) {
                            igotlock = nfsv4_lock(&clp->nfsc_lock, 1,
                                &islept, NFSCLSTATEMUTEXPTR, NULL);
                            if (islept)
                                break;
                        }
                        if (islept)
                            continue;
                        NFSUNLOCKCLSTATE();
                        cred = newnfs_getcred();
                        newnfs_copycred(&dp->nfsdl_cred, cred);
                        (void) nfscl_recalldeleg(clp, nmp, dp, fvp, cred, p, 0);
                        NFSFREECRED(cred);
                        triedrecall = 1;
                        NFSLOCKCLSTATE();
                        nfsv4_unlock(&clp->nfsc_lock, 0);
                        igotlock = 0;
                        continue;
                    }
                    *fstp = dp->nfsdl_stateid;
                    retcnt++;
                    *gotfdp = 1;
                    nfscl_cleandeleg(dp);
                    nfscl_freedeleg(&clp->nfsc_deleg, dp);
                }
                if (igotlock) {
                    nfsv4_unlock(&clp->nfsc_lock, 0);
                    igotlock = 0;
                }
                if (tvp != NULL) {
                    np = VTONFS(tvp);
                    dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh,
                        np->n_fhp->nfh_len);
                    if (dp != NULL && *gottdp == 0) {
                        /*
                         * Wait for outstanding I/O ops to be done.
                         */
                        if (dp->nfsdl_rwlock.nfslock_usecnt > 0) {
                            dp->nfsdl_rwlock.nfslock_lock |= NFSV4LOCK_WANTED;
                            (void) nfsmsleep(&dp->nfsdl_rwlock,
                                NFSCLSTATEMUTEXPTR, PZERO, "nfscld", NULL);
                            continue;
                        }
                        LIST_FOREACH(owp, &dp->nfsdl_owner, nfsow_list) {
                            if (!LIST_EMPTY(&owp->nfsow_open)) {
                                NFSUNLOCKCLSTATE();
                                return (retcnt);
                            }
                        }
                        LIST_FOREACH(lp, &dp->nfsdl_lock, nfsl_list) {
                            if (!LIST_EMPTY(&lp->nfsl_lock)) {
                                NFSUNLOCKCLSTATE();
                                return (retcnt);
                            }
                        }
                        *tstp = dp->nfsdl_stateid;
                        retcnt++;
                        *gottdp = 1;
                        nfscl_cleandeleg(dp);
                        nfscl_freedeleg(&clp->nfsc_deleg, dp);
                    }
                }
                NFSUNLOCKCLSTATE();
                return (retcnt);
        }
}

/*
 * Get a reference on the clientid associated with the mount point.
 * Return 1 if success, 0 otherwise.
 */
APPLESTATIC int
nfscl_getref(struct nfsmount *nmp)
{
        struct nfsclclient *clp;

        NFSLOCKCLSTATE();
        clp = nfscl_findcl(nmp);
        if (clp == NULL) {
                NFSUNLOCKCLSTATE();
                return (0);
        }
        nfsv4_getref(&clp->nfsc_lock, NULL, NFSCLSTATEMUTEXPTR, NULL);
        NFSUNLOCKCLSTATE();
        return (1);
}

/*
 * Release a reference on a clientid acquired with the above call.
 */
APPLESTATIC void
nfscl_relref(struct nfsmount *nmp)
{
        struct nfsclclient *clp;

        NFSLOCKCLSTATE();
        clp = nfscl_findcl(nmp);
        if (clp == NULL) {
                NFSUNLOCKCLSTATE();
                return;
        }
        nfsv4_relref(&clp->nfsc_lock);
        NFSUNLOCKCLSTATE();
}

/*
 * Save the size attribute in the delegation, since the nfsnode
 * is going away.
 */
APPLESTATIC void
nfscl_reclaimnode(vnode_t vp)
{
        struct nfsclclient *clp;
        struct nfscldeleg *dp;
        struct nfsnode *np = VTONFS(vp);
        struct nfsmount *nmp;

        nmp = VFSTONFS(vnode_mount(vp));
        if (!NFSHASNFSV4(nmp))
                return;
        NFSLOCKCLSTATE();
        clp = nfscl_findcl(nmp);
        if (clp == NULL) {
                NFSUNLOCKCLSTATE();
                return;
        }
        dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh, np->n_fhp->nfh_len);
        if (dp != NULL && (dp->nfsdl_flags & NFSCLDL_WRITE))
                dp->nfsdl_size = np->n_size;
        NFSUNLOCKCLSTATE();
}

/*
 * Get the saved size attribute in the delegation, since it is a
 * newly allocated nfsnode.
 */
APPLESTATIC void
nfscl_newnode(vnode_t vp)
{
        struct nfsclclient *clp;
        struct nfscldeleg *dp;
        struct nfsnode *np = VTONFS(vp);
        struct nfsmount *nmp;

        nmp = VFSTONFS(vnode_mount(vp));
        if (!NFSHASNFSV4(nmp))
                return;
        NFSLOCKCLSTATE();
        clp = nfscl_findcl(nmp);
        if (clp == NULL) {
                NFSUNLOCKCLSTATE();
                return;
        }
        dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh, np->n_fhp->nfh_len);
        if (dp != NULL && (dp->nfsdl_flags & NFSCLDL_WRITE))
                np->n_size = dp->nfsdl_size;
        NFSUNLOCKCLSTATE();
}

/*
 * If there is a valid write delegation for this file, set the modtime
 * to the local clock time.
 */
APPLESTATIC void
nfscl_delegmodtime(vnode_t vp)
{
        struct nfsclclient *clp;
        struct nfscldeleg *dp;
        struct nfsnode *np = VTONFS(vp);
        struct nfsmount *nmp;

        nmp = VFSTONFS(vnode_mount(vp));
        if (!NFSHASNFSV4(nmp))
                return;
        NFSLOCKCLSTATE();
        clp = nfscl_findcl(nmp);
        if (clp == NULL) {
                NFSUNLOCKCLSTATE();
                return;
        }
        dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh, np->n_fhp->nfh_len);
        if (dp != NULL && (dp->nfsdl_flags & NFSCLDL_WRITE)) {
                nanotime(&dp->nfsdl_modtime);
                dp->nfsdl_flags |= NFSCLDL_MODTIMESET;
        }
        NFSUNLOCKCLSTATE();
}

/*
 * If there is a valid write delegation for this file with a modtime set,
 * put that modtime in mtime.
 */
APPLESTATIC void
nfscl_deleggetmodtime(vnode_t vp, struct timespec *mtime)
{
        struct nfsclclient *clp;
        struct nfscldeleg *dp;
        struct nfsnode *np = VTONFS(vp);
        struct nfsmount *nmp;

        nmp = VFSTONFS(vnode_mount(vp));
        if (!NFSHASNFSV4(nmp))
                return;
        NFSLOCKCLSTATE();
        clp = nfscl_findcl(nmp);
        if (clp == NULL) {
                NFSUNLOCKCLSTATE();
                return;
        }
        dp = nfscl_finddeleg(clp, np->n_fhp->nfh_fh, np->n_fhp->nfh_len);
        if (dp != NULL &&
            (dp->nfsdl_flags & (NFSCLDL_WRITE | NFSCLDL_MODTIMESET)) ==
            (NFSCLDL_WRITE | NFSCLDL_MODTIMESET))
                *mtime = dp->nfsdl_modtime;
        NFSUNLOCKCLSTATE();
}

static int
nfscl_errmap(struct nfsrv_descript *nd, u_int32_t minorvers)
{
        short *defaulterrp, *errp;

        if (!nd->nd_repstat)
                return (0);
        if (nd->nd_procnum == NFSPROC_NOOP)
                return (txdr_unsigned(nd->nd_repstat & 0xffff));
        if (nd->nd_repstat == EBADRPC)
                return (txdr_unsigned(NFSERR_BADXDR));
        if (nd->nd_repstat == NFSERR_MINORVERMISMATCH ||
            nd->nd_repstat == NFSERR_OPILLEGAL)
                return (txdr_unsigned(nd->nd_repstat));
        if (nd->nd_repstat >= NFSERR_BADIOMODE && nd->nd_repstat < 20000 &&
            minorvers > NFSV4_MINORVERSION) {
                /* NFSv4.n error. */
                return (txdr_unsigned(nd->nd_repstat));
        }
        if (nd->nd_procnum < NFSV4OP_CBNOPS)
                errp = defaulterrp = nfscl_cberrmap[nd->nd_procnum];
        else
                return (txdr_unsigned(nd->nd_repstat));
        while (*++errp)
                if (*errp == (short)nd->nd_repstat)
                        return (txdr_unsigned(nd->nd_repstat));
        return (txdr_unsigned(*defaulterrp));
}

/*
 * Called to find/add a layout to a client.
 * This function returns the layout with a refcnt (shared lock) upon
 * success (returns 0) or with no lock/refcnt on the layout when an
 * error is returned.
 * If a layout is passed in via lypp, it is locked (exclusively locked).
 */
APPLESTATIC int
nfscl_layout(struct nfsmount *nmp, vnode_t vp, u_int8_t *fhp, int fhlen,
    nfsv4stateid_t *stateidp, int layouttype, int retonclose,
    struct nfsclflayouthead *fhlp, struct nfscllayout **lypp,
    struct ucred *cred, NFSPROC_T *p)
{
        struct nfsclclient *clp;
        struct nfscllayout *lyp, *tlyp;
        struct nfsclflayout *flp;
        struct nfsnode *np = VTONFS(vp);
        mount_t mp;
        int layout_passed_in;

        mp = nmp->nm_mountp;
        layout_passed_in = 1;
        tlyp = NULL;
        lyp = *lypp;
        if (lyp == NULL) {
                layout_passed_in = 0;
                tlyp = malloc(sizeof(*tlyp) + fhlen - 1, M_NFSLAYOUT,
                    M_WAITOK | M_ZERO);
        }

        NFSLOCKCLSTATE();
        clp = nmp->nm_clp;
        if (clp == NULL) {
                if (layout_passed_in != 0)
                        nfsv4_unlock(&lyp->nfsly_lock, 0);
                NFSUNLOCKCLSTATE();
                if (tlyp != NULL)
                        free(tlyp, M_NFSLAYOUT);
                return (EPERM);
        }
        if (lyp == NULL) {
                /*
                 * Although no lyp was passed in, another thread might have
                 * allocated one. If one is found, just increment it's ref
                 * count and return it.
                 */
                lyp = nfscl_findlayout(clp, fhp, fhlen);
                if (lyp == NULL) {
                        lyp = tlyp;
                        tlyp = NULL;
                        lyp->nfsly_stateid.seqid = stateidp->seqid;
                        lyp->nfsly_stateid.other[0] = stateidp->other[0];
                        lyp->nfsly_stateid.other[1] = stateidp->other[1];
                        lyp->nfsly_stateid.other[2] = stateidp->other[2];
                        lyp->nfsly_lastbyte = 0;
                        LIST_INIT(&lyp->nfsly_flayread);
                        LIST_INIT(&lyp->nfsly_flayrw);
                        LIST_INIT(&lyp->nfsly_recall);
                        lyp->nfsly_filesid[0] = np->n_vattr.na_filesid[0];
                        lyp->nfsly_filesid[1] = np->n_vattr.na_filesid[1];
                        lyp->nfsly_clp = clp;
                        if (layouttype == NFSLAYOUT_FLEXFILE)
                                lyp->nfsly_flags = NFSLY_FLEXFILE;
                        else
                                lyp->nfsly_flags = NFSLY_FILES;
                        if (retonclose != 0)
                                lyp->nfsly_flags |= NFSLY_RETONCLOSE;
                        lyp->nfsly_fhlen = fhlen;
                        NFSBCOPY(fhp, lyp->nfsly_fh, fhlen);
                        TAILQ_INSERT_HEAD(&clp->nfsc_layout, lyp, nfsly_list);
                        LIST_INSERT_HEAD(NFSCLLAYOUTHASH(clp, fhp, fhlen), lyp,
                            nfsly_hash);
                        lyp->nfsly_timestamp = NFSD_MONOSEC + 120;
                        nfscl_layoutcnt++;
                } else {
                        if (retonclose != 0)
                                lyp->nfsly_flags |= NFSLY_RETONCLOSE;
                        TAILQ_REMOVE(&clp->nfsc_layout, lyp, nfsly_list);
                        TAILQ_INSERT_HEAD(&clp->nfsc_layout, lyp, nfsly_list);
                        lyp->nfsly_timestamp = NFSD_MONOSEC + 120;
                }
                nfsv4_getref(&lyp->nfsly_lock, NULL, NFSCLSTATEMUTEXPTR, mp);
                if (NFSCL_FORCEDISM(mp)) {
                        NFSUNLOCKCLSTATE();
                        if (tlyp != NULL)
                                free(tlyp, M_NFSLAYOUT);
                        return (EPERM);
                }
                *lypp = lyp;
        } else
                lyp->nfsly_stateid.seqid = stateidp->seqid;

        /* Merge the new list of File Layouts into the list. */
        flp = LIST_FIRST(fhlp);
        if (flp != NULL) {
                if (flp->nfsfl_iomode == NFSLAYOUTIOMODE_READ)
                        nfscl_mergeflayouts(&lyp->nfsly_flayread, fhlp);
                else
                        nfscl_mergeflayouts(&lyp->nfsly_flayrw, fhlp);
        }
        if (layout_passed_in != 0)
                nfsv4_unlock(&lyp->nfsly_lock, 1);
        NFSUNLOCKCLSTATE();
        if (tlyp != NULL)
                free(tlyp, M_NFSLAYOUT);
        return (0);
}

/*
 * Search for a layout by MDS file handle.
 * If one is found, it is returned with a refcnt (shared lock) iff
 * retflpp returned non-NULL and locked (exclusive locked) iff retflpp is
 * returned NULL.
 */
struct nfscllayout *
nfscl_getlayout(struct nfsclclient *clp, uint8_t *fhp, int fhlen,
    uint64_t off, struct nfsclflayout **retflpp, int *recalledp)
{
        struct nfscllayout *lyp;
        mount_t mp;
        int error, igotlock;

        mp = clp->nfsc_nmp->nm_mountp;
        *recalledp = 0;
        *retflpp = NULL;
        NFSLOCKCLSTATE();
        lyp = nfscl_findlayout(clp, fhp, fhlen);
        if (lyp != NULL) {
                if ((lyp->nfsly_flags & NFSLY_RECALL) == 0) {
                        TAILQ_REMOVE(&clp->nfsc_layout, lyp, nfsly_list);
                        TAILQ_INSERT_HEAD(&clp->nfsc_layout, lyp, nfsly_list);
                        lyp->nfsly_timestamp = NFSD_MONOSEC + 120;
                        error = nfscl_findlayoutforio(lyp, off,
                            NFSV4OPEN_ACCESSREAD, retflpp);
                        if (error == 0)
                                nfsv4_getref(&lyp->nfsly_lock, NULL,
                                    NFSCLSTATEMUTEXPTR, mp);
                        else {
                                do {
                                        igotlock = nfsv4_lock(&lyp->nfsly_lock,
                                            1, NULL, NFSCLSTATEMUTEXPTR, mp);
                                } while (igotlock == 0 && !NFSCL_FORCEDISM(mp));
                                *retflpp = NULL;
                        }
                        if (NFSCL_FORCEDISM(mp)) {
                                lyp = NULL;
                                *recalledp = 1;
                        }
                } else {
                        lyp = NULL;
                        *recalledp = 1;
                }
        }
        NFSUNLOCKCLSTATE();
        return (lyp);
}

/*
 * Search for a layout by MDS file handle. If one is found, mark in to be
 * recalled, if it already marked "return on close".
 */
static void
nfscl_retoncloselayout(vnode_t vp, struct nfsclclient *clp, uint8_t *fhp,
    int fhlen, struct nfsclrecalllayout **recallpp)
{
        struct nfscllayout *lyp;
        uint32_t iomode;

        if (vp->v_type != VREG || !NFSHASPNFS(VFSTONFS(vnode_mount(vp))) ||
            nfscl_enablecallb == 0 || nfs_numnfscbd == 0 ||
            (VTONFS(vp)->n_flag & NNOLAYOUT) != 0)
                return;
        lyp = nfscl_findlayout(clp, fhp, fhlen);
        if (lyp != NULL && (lyp->nfsly_flags & (NFSLY_RETONCLOSE |
            NFSLY_RECALL)) == NFSLY_RETONCLOSE) {
                iomode = 0;
                if (!LIST_EMPTY(&lyp->nfsly_flayread))
                        iomode |= NFSLAYOUTIOMODE_READ;
                if (!LIST_EMPTY(&lyp->nfsly_flayrw))
                        iomode |= NFSLAYOUTIOMODE_RW;
                (void)nfscl_layoutrecall(NFSLAYOUTRETURN_FILE, lyp, iomode,
                    0, UINT64_MAX, lyp->nfsly_stateid.seqid, 0, 0, NULL,
                    *recallpp);
                NFSCL_DEBUG(4, "retoncls recall iomode=%d\n", iomode);
                *recallpp = NULL;
        }
}

/*
 * Mark the layout to be recalled and with an error.
 * Also, disable the dsp from further use.
 */
void
nfscl_dserr(uint32_t op, uint32_t stat, struct nfscldevinfo *dp,
    struct nfscllayout *lyp, struct nfsclds *dsp)
{
        struct nfsclrecalllayout *recallp;
        uint32_t iomode;

        printf("DS being disabled, error=%d\n", stat);
        /* Set up the return of the layout. */
        recallp = malloc(sizeof(*recallp), M_NFSLAYRECALL, M_WAITOK);
        iomode = 0;
        NFSLOCKCLSTATE();
        if ((lyp->nfsly_flags & NFSLY_RECALL) == 0) {
                if (!LIST_EMPTY(&lyp->nfsly_flayread))
                        iomode |= NFSLAYOUTIOMODE_READ;
                if (!LIST_EMPTY(&lyp->nfsly_flayrw))
                        iomode |= NFSLAYOUTIOMODE_RW;
                (void)nfscl_layoutrecall(NFSLAYOUTRETURN_FILE, lyp, iomode,
                    0, UINT64_MAX, lyp->nfsly_stateid.seqid, stat, op,
                    dp->nfsdi_deviceid, recallp);
                NFSUNLOCKCLSTATE();
                NFSCL_DEBUG(4, "nfscl_dserr recall iomode=%d\n", iomode);
        } else {
                NFSUNLOCKCLSTATE();
                free(recallp, M_NFSLAYRECALL);
        }

        /* And shut the TCP connection down. */
        nfscl_cancelreqs(dsp);
}

/*
 * Cancel all RPCs for this "dsp" by closing the connection.
 * Also, mark the session as defunct.
 * If NFSCLDS_SAMECONN is set, the connection is shared with other DSs and
 * cannot be shut down.
 */
APPLESTATIC void
nfscl_cancelreqs(struct nfsclds *dsp)
{
        struct __rpc_client *cl;
        static int non_event;

        NFSLOCKDS(dsp);
        if ((dsp->nfsclds_flags & (NFSCLDS_CLOSED | NFSCLDS_SAMECONN)) == 0 &&
            dsp->nfsclds_sockp != NULL &&
            dsp->nfsclds_sockp->nr_client != NULL) {
                dsp->nfsclds_flags |= NFSCLDS_CLOSED;
                cl = dsp->nfsclds_sockp->nr_client;
                dsp->nfsclds_sess.nfsess_defunct = 1;
                NFSUNLOCKDS(dsp);
                CLNT_CLOSE(cl);
                /*
                 * This 1sec sleep is done to reduce the number of reconnect
                 * attempts made on the DS while it has failed.
                 */
                tsleep(&non_event, PVFS, "ndscls", hz);
                return;
        }
        NFSUNLOCKDS(dsp);
}

/*
 * Dereference a layout.
 */
void
nfscl_rellayout(struct nfscllayout *lyp, int exclocked)
{

        NFSLOCKCLSTATE();
        if (exclocked != 0)
                nfsv4_unlock(&lyp->nfsly_lock, 0);
        else
                nfsv4_relref(&lyp->nfsly_lock);
        NFSUNLOCKCLSTATE();
}

/*
 * Search for a devinfo by deviceid. If one is found, return it after
 * acquiring a reference count on it.
 */
struct nfscldevinfo *
nfscl_getdevinfo(struct nfsclclient *clp, uint8_t *deviceid,
    struct nfscldevinfo *dip)
{

        NFSLOCKCLSTATE();
        if (dip == NULL)
                dip = nfscl_finddevinfo(clp, deviceid);
        if (dip != NULL)
                dip->nfsdi_refcnt++;
        NFSUNLOCKCLSTATE();
        return (dip);
}

/*
 * Dereference a devinfo structure.
 */
static void
nfscl_reldevinfo_locked(struct nfscldevinfo *dip)
{

        dip->nfsdi_refcnt--;
        if (dip->nfsdi_refcnt == 0)
                wakeup(&dip->nfsdi_refcnt);
}

/*
 * Dereference a devinfo structure.
 */
void
nfscl_reldevinfo(struct nfscldevinfo *dip)
{

        NFSLOCKCLSTATE();
        nfscl_reldevinfo_locked(dip);
        NFSUNLOCKCLSTATE();
}

/*
 * Find a layout for this file handle. Return NULL upon failure.
 */
static struct nfscllayout *
nfscl_findlayout(struct nfsclclient *clp, u_int8_t *fhp, int fhlen)
{
        struct nfscllayout *lyp;

        LIST_FOREACH(lyp, NFSCLLAYOUTHASH(clp, fhp, fhlen), nfsly_hash)
                if (lyp->nfsly_fhlen == fhlen &&
                    !NFSBCMP(lyp->nfsly_fh, fhp, fhlen))
                        break;
        return (lyp);
}

/*
 * Find a devinfo for this deviceid. Return NULL upon failure.
 */
static struct nfscldevinfo *
nfscl_finddevinfo(struct nfsclclient *clp, uint8_t *deviceid)
{
        struct nfscldevinfo *dip;

        LIST_FOREACH(dip, &clp->nfsc_devinfo, nfsdi_list)
                if (NFSBCMP(dip->nfsdi_deviceid, deviceid, NFSX_V4DEVICEID)
                    == 0)
                        break;
        return (dip);
}

/*
 * Merge the new file layout list into the main one, maintaining it in
 * increasing offset order.
 */
static void
nfscl_mergeflayouts(struct nfsclflayouthead *fhlp,
    struct nfsclflayouthead *newfhlp)
{
        struct nfsclflayout *flp, *nflp, *prevflp, *tflp;

        flp = LIST_FIRST(fhlp);
        prevflp = NULL;
        LIST_FOREACH_SAFE(nflp, newfhlp, nfsfl_list, tflp) {
                while (flp != NULL && flp->nfsfl_off < nflp->nfsfl_off) {
                        prevflp = flp;
                        flp = LIST_NEXT(flp, nfsfl_list);
                }
                if (prevflp == NULL)
                        LIST_INSERT_HEAD(fhlp, nflp, nfsfl_list);
                else
                        LIST_INSERT_AFTER(prevflp, nflp, nfsfl_list);
                prevflp = nflp;
        }
}

/*
 * Add this nfscldevinfo to the client, if it doesn't already exist.
 * This function consumes the structure pointed at by dip, if not NULL.
 */
APPLESTATIC int
nfscl_adddevinfo(struct nfsmount *nmp, struct nfscldevinfo *dip, int ind,
    struct nfsclflayout *flp)
{
        struct nfsclclient *clp;
        struct nfscldevinfo *tdip;
        uint8_t *dev;

        NFSLOCKCLSTATE();
        clp = nmp->nm_clp;
        if (clp == NULL) {
                NFSUNLOCKCLSTATE();
                if (dip != NULL)
                        free(dip, M_NFSDEVINFO);
                return (ENODEV);
        }
        if ((flp->nfsfl_flags & NFSFL_FILE) != 0)
                dev = flp->nfsfl_dev;
        else
                dev = flp->nfsfl_ffm[ind].dev;
        tdip = nfscl_finddevinfo(clp, dev);
        if (tdip != NULL) {
                tdip->nfsdi_layoutrefs++;
                if ((flp->nfsfl_flags & NFSFL_FILE) != 0)
                        flp->nfsfl_devp = tdip;
                else
                        flp->nfsfl_ffm[ind].devp = tdip;
                nfscl_reldevinfo_locked(tdip);
                NFSUNLOCKCLSTATE();
                if (dip != NULL)
                        free(dip, M_NFSDEVINFO);
                return (0);
        }
        if (dip != NULL) {
                LIST_INSERT_HEAD(&clp->nfsc_devinfo, dip, nfsdi_list);
                dip->nfsdi_layoutrefs = 1;
                if ((flp->nfsfl_flags & NFSFL_FILE) != 0)
                        flp->nfsfl_devp = dip;
                else
                        flp->nfsfl_ffm[ind].devp = dip;
        }
        NFSUNLOCKCLSTATE();
        if (dip == NULL)
                return (ENODEV);
        return (0);
}

/*
 * Free up a layout structure and associated file layout structure(s).
 */
APPLESTATIC void
nfscl_freelayout(struct nfscllayout *layp)
{
        struct nfsclflayout *flp, *nflp;
        struct nfsclrecalllayout *rp, *nrp;

        LIST_FOREACH_SAFE(flp, &layp->nfsly_flayread, nfsfl_list, nflp) {
                LIST_REMOVE(flp, nfsfl_list);
                nfscl_freeflayout(flp);
        }
        LIST_FOREACH_SAFE(flp, &layp->nfsly_flayrw, nfsfl_list, nflp) {
                LIST_REMOVE(flp, nfsfl_list);
                nfscl_freeflayout(flp);
        }
        LIST_FOREACH_SAFE(rp, &layp->nfsly_recall, nfsrecly_list, nrp) {
                LIST_REMOVE(rp, nfsrecly_list);
                free(rp, M_NFSLAYRECALL);
        }
        nfscl_layoutcnt--;
        free(layp, M_NFSLAYOUT);
}

/*
 * Free up a file layout structure.
 */
APPLESTATIC void
nfscl_freeflayout(struct nfsclflayout *flp)
{
        int i, j;

        if ((flp->nfsfl_flags & NFSFL_FILE) != 0) {
                for (i = 0; i < flp->nfsfl_fhcnt; i++)
                        free(flp->nfsfl_fh[i], M_NFSFH);
                if (flp->nfsfl_devp != NULL)
                        flp->nfsfl_devp->nfsdi_layoutrefs--;
        }
        if ((flp->nfsfl_flags & NFSFL_FLEXFILE) != 0)
                for (i = 0; i < flp->nfsfl_mirrorcnt; i++) {
                        for (j = 0; j < flp->nfsfl_ffm[i].fhcnt; j++)
                                free(flp->nfsfl_ffm[i].fh[j], M_NFSFH);
                        if (flp->nfsfl_ffm[i].devp != NULL)     
                                flp->nfsfl_ffm[i].devp->nfsdi_layoutrefs--;     
                }
        free(flp, M_NFSFLAYOUT);
}

/*
 * Free up a file layout devinfo structure.
 */
APPLESTATIC void
nfscl_freedevinfo(struct nfscldevinfo *dip)
{

        free(dip, M_NFSDEVINFO);
}

/*
 * Mark any layouts that match as recalled.
 */
static int
nfscl_layoutrecall(int recalltype, struct nfscllayout *lyp, uint32_t iomode,
    uint64_t off, uint64_t len, uint32_t stateseqid, uint32_t stat, uint32_t op,
    char *devid, struct nfsclrecalllayout *recallp)
{
        struct nfsclrecalllayout *rp, *orp;

        recallp->nfsrecly_recalltype = recalltype;
        recallp->nfsrecly_iomode = iomode;
        recallp->nfsrecly_stateseqid = stateseqid;
        recallp->nfsrecly_off = off;
        recallp->nfsrecly_len = len;
        recallp->nfsrecly_stat = stat;
        recallp->nfsrecly_op = op;
        if (devid != NULL)
                NFSBCOPY(devid, recallp->nfsrecly_devid, NFSX_V4DEVICEID);
        /*
         * Order the list as file returns first, followed by fsid and any
         * returns, both in increasing stateseqid order.
         * Note that the seqids wrap around, so 1 is after 0xffffffff.
         * (I'm not sure this is correct because I find RFC5661 confusing
         *  on this, but hopefully it will work ok.)
         */
        orp = NULL;
        LIST_FOREACH(rp, &lyp->nfsly_recall, nfsrecly_list) {
                orp = rp;
                if ((recalltype == NFSLAYOUTRETURN_FILE &&
                     (rp->nfsrecly_recalltype != NFSLAYOUTRETURN_FILE ||
                      nfscl_seq(stateseqid, rp->nfsrecly_stateseqid) != 0)) ||
                    (recalltype != NFSLAYOUTRETURN_FILE &&
                     rp->nfsrecly_recalltype != NFSLAYOUTRETURN_FILE &&
                     nfscl_seq(stateseqid, rp->nfsrecly_stateseqid) != 0)) {
                        LIST_INSERT_BEFORE(rp, recallp, nfsrecly_list);
                        break;
                }

                /*
                 * Put any error return on all the file returns that will
                 * preceed this one.
                 */
                if (rp->nfsrecly_recalltype == NFSLAYOUTRETURN_FILE &&
                   stat != 0 && rp->nfsrecly_stat == 0) {
                        rp->nfsrecly_stat = stat;
                        rp->nfsrecly_op = op;
                        if (devid != NULL)
                                NFSBCOPY(devid, rp->nfsrecly_devid,
                                    NFSX_V4DEVICEID);
                }
        }
        if (rp == NULL) {
                if (orp == NULL)
                        LIST_INSERT_HEAD(&lyp->nfsly_recall, recallp,
                            nfsrecly_list);
                else
                        LIST_INSERT_AFTER(orp, recallp, nfsrecly_list);
        }
        lyp->nfsly_flags |= NFSLY_RECALL;
        wakeup(lyp->nfsly_clp);
        return (0);
}

/*
 * Compare the two seqids for ordering. The trick is that the seqids can
 * wrap around from 0xffffffff->0, so check for the cases where one
 * has wrapped around.
 * Return 1 if seqid1 comes before seqid2, 0 otherwise.
 */
static int
nfscl_seq(uint32_t seqid1, uint32_t seqid2)
{

        if (seqid2 > seqid1 && (seqid2 - seqid1) >= 0x7fffffff)
                /* seqid2 has wrapped around. */
                return (0);
        if (seqid1 > seqid2 && (seqid1 - seqid2) >= 0x7fffffff)
                /* seqid1 has wrapped around. */
                return (1);
        if (seqid1 <= seqid2)
                return (1);
        return (0);
}

/*
 * Do a layout return for each of the recalls.
 */
static void
nfscl_layoutreturn(struct nfsmount *nmp, struct nfscllayout *lyp,
    struct ucred *cred, NFSPROC_T *p)
{
        struct nfsclrecalllayout *rp;
        nfsv4stateid_t stateid;
        int layouttype;

        NFSBCOPY(lyp->nfsly_stateid.other, stateid.other, NFSX_STATEIDOTHER);
        stateid.seqid = lyp->nfsly_stateid.seqid;
        if ((lyp->nfsly_flags & NFSLY_FILES) != 0)
                layouttype = NFSLAYOUT_NFSV4_1_FILES;
        else
                layouttype = NFSLAYOUT_FLEXFILE;
        LIST_FOREACH(rp, &lyp->nfsly_recall, nfsrecly_list) {
                (void)nfsrpc_layoutreturn(nmp, lyp->nfsly_fh,
                    lyp->nfsly_fhlen, 0, layouttype,
                    rp->nfsrecly_iomode, rp->nfsrecly_recalltype,
                    rp->nfsrecly_off, rp->nfsrecly_len,
                    &stateid, cred, p, rp->nfsrecly_stat, rp->nfsrecly_op,
                    rp->nfsrecly_devid);
        }
}

/*
 * Do the layout commit for a file layout.
 */
static void
nfscl_dolayoutcommit(struct nfsmount *nmp, struct nfscllayout *lyp,
    struct ucred *cred, NFSPROC_T *p)
{
        struct nfsclflayout *flp;
        uint64_t len;
        int error, layouttype;

        if ((lyp->nfsly_flags & NFSLY_FILES) != 0)
                layouttype = NFSLAYOUT_NFSV4_1_FILES;
        else
                layouttype = NFSLAYOUT_FLEXFILE;
        LIST_FOREACH(flp, &lyp->nfsly_flayrw, nfsfl_list) {
                if (layouttype == NFSLAYOUT_FLEXFILE &&
                    (flp->nfsfl_fflags & NFSFLEXFLAG_NO_LAYOUTCOMMIT) != 0) {
                        NFSCL_DEBUG(4, "Flex file: no layoutcommit\n");
                        /* If not supported, don't bother doing it. */
                        NFSLOCKMNT(nmp);
                        nmp->nm_state |= NFSSTA_NOLAYOUTCOMMIT;
                        NFSUNLOCKMNT(nmp);
                        break;
                } else if (flp->nfsfl_off <= lyp->nfsly_lastbyte) {
                        len = flp->nfsfl_end - flp->nfsfl_off;
                        error = nfsrpc_layoutcommit(nmp, lyp->nfsly_fh,
                            lyp->nfsly_fhlen, 0, flp->nfsfl_off, len,
                            lyp->nfsly_lastbyte, &lyp->nfsly_stateid,
                            layouttype, cred, p, NULL);
                        NFSCL_DEBUG(4, "layoutcommit err=%d\n", error);
                        if (error == NFSERR_NOTSUPP) {
                                /* If not supported, don't bother doing it. */
                                NFSLOCKMNT(nmp);
                                nmp->nm_state |= NFSSTA_NOLAYOUTCOMMIT;
                                NFSUNLOCKMNT(nmp);
                                break;
                        }
                }
        }
}

/*
 * Commit all layouts for a file (vnode).
 */
int
nfscl_layoutcommit(vnode_t vp, NFSPROC_T *p)
{
        struct nfsclclient *clp;
        struct nfscllayout *lyp;
        struct nfsnode *np = VTONFS(vp);
        mount_t mp;
        struct nfsmount *nmp;

        mp = vnode_mount(vp);
        nmp = VFSTONFS(mp);
        if (NFSHASNOLAYOUTCOMMIT(nmp))
                return (0);
        NFSLOCKCLSTATE();
        clp = nmp->nm_clp;
        if (clp == NULL) {
                NFSUNLOCKCLSTATE();
                return (EPERM);
        }
        lyp = nfscl_findlayout(clp, np->n_fhp->nfh_fh, np->n_fhp->nfh_len);
        if (lyp == NULL) {
                NFSUNLOCKCLSTATE();
                return (EPERM);
        }
        nfsv4_getref(&lyp->nfsly_lock, NULL, NFSCLSTATEMUTEXPTR, mp);
        if (NFSCL_FORCEDISM(mp)) {
                NFSUNLOCKCLSTATE();
                return (EPERM);
        }
tryagain:
        if ((lyp->nfsly_flags & NFSLY_WRITTEN) != 0) {
                lyp->nfsly_flags &= ~NFSLY_WRITTEN;
                NFSUNLOCKCLSTATE();
                NFSCL_DEBUG(4, "do layoutcommit2\n");
                nfscl_dolayoutcommit(clp->nfsc_nmp, lyp, NFSPROCCRED(p), p);
                NFSLOCKCLSTATE();
                goto tryagain;
        }
        nfsv4_relref(&lyp->nfsly_lock);
        NFSUNLOCKCLSTATE();
        return (0);
}