dmake: do not set MAKEFLAGS=k

[unleashed/tickless.git] / kernel / fs / nfs / nfs4_client.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1986, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2017 by Delphix. All rights reserved.
 */

/*
 *      Copyright (c) 1983,1984,1985,1986,1987,1988,1989  AT&T.
 *      All Rights Reserved
 */

#include <sys/param.h>
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/thread.h>
#include <sys/t_lock.h>
#include <sys/time.h>
#include <sys/vnode.h>
#include <sys/vfs.h>
#include <sys/errno.h>
#include <sys/buf.h>
#include <sys/stat.h>
#include <sys/cred.h>
#include <sys/kmem.h>
#include <sys/debug.h>
#include <sys/dnlc.h>
#include <sys/vmsystm.h>
#include <sys/flock.h>
#include <sys/share.h>
#include <sys/cmn_err.h>
#include <sys/tiuser.h>
#include <sys/sysmacros.h>
#include <sys/callb.h>
#include <sys/acl.h>
#include <sys/kstat.h>
#include <sys/signal.h>
#include <sys/disp.h>
#include <sys/atomic.h>
#include <sys/list.h>
#include <sys/sdt.h>

#include <rpc/types.h>
#include <rpc/xdr.h>
#include <rpc/auth.h>
#include <rpc/clnt.h>

#include <nfs/nfs.h>
#include <nfs/nfs_clnt.h>
#include <nfs/nfs_acl.h>

#include <nfs/nfs4.h>
#include <nfs/rnode4.h>
#include <nfs/nfs4_clnt.h>

#include <vm/hat.h>
#include <vm/as.h>
#include <vm/page.h>
#include <vm/pvn.h>
#include <vm/seg.h>
#include <vm/seg_map.h>
#include <vm/seg_vn.h>

#include <sys/ddi.h>

/*
 * Arguments to page-flush thread.
 */
typedef struct {
        vnode_t *vp;
        cred_t *cr;
} pgflush_t;

#ifdef DEBUG
int nfs4_client_lease_debug;
int nfs4_sharedfh_debug;
int nfs4_fname_debug;

/* temporary: panic if v_type is inconsistent with r_attr va_type */
int nfs4_vtype_debug;

uint_t nfs4_tsd_key;
#endif

static time_t   nfs4_client_resumed = 0;
static  callb_id_t cid = 0;

static int      nfs4renew(nfs4_server_t *);
static void     nfs4_attrcache_va(vnode_t *, nfs4_ga_res_t *, int);
static void     nfs4_pgflush_thread(pgflush_t *);

static boolean_t nfs4_client_cpr_callb(void *, int);

struct mi4_globals {
        kmutex_t        mig_lock;  /* lock protecting mig_list */
        list_t          mig_list;  /* list of NFS v4 mounts in zone */
        boolean_t       mig_destructor_called;
};

static zone_key_t mi4_list_key;

/*
 * Attributes caching:
 *
 * Attributes are cached in the rnode in struct vattr form.
 * There is a time associated with the cached attributes (r_time_attr_inval)
 * which tells whether the attributes are valid. The time is initialized
 * to the difference between current time and the modify time of the vnode
 * when new attributes are cached. This allows the attributes for
 * files that have changed recently to be timed out sooner than for files
 * that have not changed for a long time. There are minimum and maximum
 * timeout values that can be set per mount point.
 */

/*
 * If a cache purge is in progress, wait for it to finish.
 *
 * The current thread must not be in the middle of an
 * nfs4_start_op/nfs4_end_op region.  Otherwise, there could be a deadlock
 * between this thread, a recovery thread, and the page flush thread.
 */
int
nfs4_waitfor_purge_complete(vnode_t *vp)
{
        rnode4_t *rp;
        k_sigset_t smask;

        rp = VTOR4(vp);
        if ((rp->r_serial != NULL && rp->r_serial != curthread) ||
            ((rp->r_flags & R4PGFLUSH) && rp->r_pgflush != curthread)) {
                mutex_enter(&rp->r_statelock);
                sigintr(&smask, VTOMI4(vp)->mi_flags & MI4_INT);
                while ((rp->r_serial != NULL && rp->r_serial != curthread) ||
                    ((rp->r_flags & R4PGFLUSH) &&
                    rp->r_pgflush != curthread)) {
                        if (!cv_wait_sig(&rp->r_cv, &rp->r_statelock)) {
                                sigunintr(&smask);
                                mutex_exit(&rp->r_statelock);
                                return (EINTR);
                        }
                }
                sigunintr(&smask);
                mutex_exit(&rp->r_statelock);
        }
        return (0);
}

/*
 * Validate caches by checking cached attributes. If they have timed out,
 * then get new attributes from the server.  As a side effect, cache
 * invalidation is done if the attributes have changed.
 *
 * If the attributes have not timed out and if there is a cache
 * invalidation being done by some other thread, then wait until that
 * thread has completed the cache invalidation.
 */
int
nfs4_validate_caches(vnode_t *vp, cred_t *cr)
{
        int error;
        nfs4_ga_res_t gar;

        if (ATTRCACHE4_VALID(vp)) {
                error = nfs4_waitfor_purge_complete(vp);
                if (error)
                        return (error);
                return (0);
        }

        return (nfs4_getattr_otw(vp, &gar, cr, 0));
}

/*
 * Fill in attribute from the cache.
 * If valid, then return 0 to indicate that no error occurred,
 * otherwise return 1 to indicate that an error occurred.
 */
static int
nfs4_getattr_cache(vnode_t *vp, struct vattr *vap)
{
        rnode4_t *rp;

        rp = VTOR4(vp);
        mutex_enter(&rp->r_statelock);
        mutex_enter(&rp->r_statev4_lock);
        if (ATTRCACHE4_VALID(vp)) {
                mutex_exit(&rp->r_statev4_lock);
                /*
                 * Cached attributes are valid
                 */
                *vap = rp->r_attr;
                mutex_exit(&rp->r_statelock);
                return (0);
        }
        mutex_exit(&rp->r_statev4_lock);
        mutex_exit(&rp->r_statelock);
        return (1);
}


/*
 * If returned error is ESTALE flush all caches.  The nfs4_purge_caches()
 * call is synchronous because all the pages were invalidated by the
 * nfs4_invalidate_pages() call.
 */
void
nfs4_purge_stale_fh(int errno, vnode_t *vp, cred_t *cr)
{
        struct rnode4 *rp = VTOR4(vp);

        /* Ensure that the ..._end_op() call has been done */
        ASSERT(tsd_get(nfs4_tsd_key) == NULL);

        if (errno != ESTALE)
                return;

        mutex_enter(&rp->r_statelock);
        rp->r_flags |= R4STALE;
        if (!rp->r_error)
                rp->r_error = errno;
        mutex_exit(&rp->r_statelock);
        if (nfs4_has_pages(vp))
                nfs4_invalidate_pages(vp, 0, cr);
        nfs4_purge_caches(vp, NFS4_PURGE_DNLC, cr, FALSE);
}

/*
 * Purge all of the various NFS `data' caches.  If "asyncpg" is TRUE, the
 * page purge is done asynchronously.
 */
void
nfs4_purge_caches(vnode_t *vp, int purge_dnlc, cred_t *cr, int asyncpg)
{
        rnode4_t *rp;
        char *contents;
        vnode_t *xattr;
        int size;
        int pgflush;                    /* are we the page flush thread? */

        /*
         * Purge the DNLC for any entries which refer to this file.
         */
        if (vp->v_count > 1 &&
            (vp->v_type == VDIR || purge_dnlc == NFS4_PURGE_DNLC))
                dnlc_purge_vp(vp);

        /*
         * Clear any readdir state bits and purge the readlink response cache.
         */
        rp = VTOR4(vp);
        mutex_enter(&rp->r_statelock);
        rp->r_flags &= ~R4LOOKUP;
        contents = rp->r_symlink.contents;
        size = rp->r_symlink.size;
        rp->r_symlink.contents = NULL;

        xattr = rp->r_xattr_dir;
        rp->r_xattr_dir = NULL;

        /*
         * Purge pathconf cache too.
         */
        rp->r_pathconf.pc4_xattr_valid = 0;
        rp->r_pathconf.pc4_cache_valid = 0;

        pgflush = (curthread == rp->r_pgflush);
        mutex_exit(&rp->r_statelock);

        if (contents != NULL) {

                kmem_free((void *)contents, size);
        }

        if (xattr != NULL)
                VN_RELE(xattr);

        /*
         * Flush the page cache.  If the current thread is the page flush
         * thread, don't initiate a new page flush.  There's no need for
         * it, and doing it correctly is hard.
         */
        if (nfs4_has_pages(vp) && !pgflush) {
                if (!asyncpg) {
                        (void) nfs4_waitfor_purge_complete(vp);
                        nfs4_flush_pages(vp, cr);
                } else {
                        pgflush_t *args;

                        /*
                         * We don't hold r_statelock while creating the
                         * thread, in case the call blocks.  So we use a
                         * flag to indicate that a page flush thread is
                         * active.
                         */
                        mutex_enter(&rp->r_statelock);
                        if (rp->r_flags & R4PGFLUSH) {
                                mutex_exit(&rp->r_statelock);
                        } else {
                                rp->r_flags |= R4PGFLUSH;
                                mutex_exit(&rp->r_statelock);

                                args = kmem_alloc(sizeof (pgflush_t),
                                    KM_SLEEP);
                                args->vp = vp;
                                VN_HOLD(args->vp);
                                args->cr = cr;
                                crhold(args->cr);
                                (void) zthread_create(NULL, 0,
                                    nfs4_pgflush_thread, args, 0,
                                    minclsyspri);
                        }
                }
        }

        /*
         * Flush the readdir response cache.
         */
        nfs4_purge_rddir_cache(vp);
}

/*
 * Invalidate all pages for the given file, after writing back the dirty
 * ones.
 */

void
nfs4_flush_pages(vnode_t *vp, cred_t *cr)
{
        int error;
        rnode4_t *rp = VTOR4(vp);

        error = fop_putpage(vp, 0, 0, B_INVAL, cr, NULL);
        if (error == ENOSPC || error == EDQUOT) {
                mutex_enter(&rp->r_statelock);
                if (!rp->r_error)
                        rp->r_error = error;
                mutex_exit(&rp->r_statelock);
        }
}

/*
 * Page flush thread.
 */

static void
nfs4_pgflush_thread(pgflush_t *args)
{
        rnode4_t *rp = VTOR4(args->vp);

        /* remember which thread we are, so we don't deadlock ourselves */
        mutex_enter(&rp->r_statelock);
        ASSERT(rp->r_pgflush == NULL);
        rp->r_pgflush = curthread;
        mutex_exit(&rp->r_statelock);

        nfs4_flush_pages(args->vp, args->cr);

        mutex_enter(&rp->r_statelock);
        rp->r_pgflush = NULL;
        rp->r_flags &= ~R4PGFLUSH;
        cv_broadcast(&rp->r_cv);
        mutex_exit(&rp->r_statelock);

        VN_RELE(args->vp);
        crfree(args->cr);
        kmem_free(args, sizeof (pgflush_t));
        zthread_exit();
}

/*
 * Purge the readdir cache of all entries which are not currently
 * being filled.
 */
void
nfs4_purge_rddir_cache(vnode_t *vp)
{
        rnode4_t *rp;

        rp = VTOR4(vp);

        mutex_enter(&rp->r_statelock);
        rp->r_direof = NULL;
        rp->r_flags &= ~R4LOOKUP;
        rp->r_flags |= R4READDIRWATTR;
        rddir4_cache_purge(rp);
        mutex_exit(&rp->r_statelock);
}

/*
 * Set attributes cache for given vnode using virtual attributes.  There is
 * no cache validation, but if the attributes are deemed to be stale, they
 * are ignored.  This corresponds to nfs3_attrcache().
 *
 * Set the timeout value on the attribute cache and fill it
 * with the passed in attributes.
 */
void
nfs4_attrcache_noinval(vnode_t *vp, nfs4_ga_res_t *garp, hrtime_t t)
{
        rnode4_t *rp = VTOR4(vp);

        mutex_enter(&rp->r_statelock);
        if (rp->r_time_attr_saved <= t)
                nfs4_attrcache_va(vp, garp, FALSE);
        mutex_exit(&rp->r_statelock);
}

/*
 * Use the passed in virtual attributes to check to see whether the
 * data and metadata caches are valid, cache the new attributes, and
 * then do the cache invalidation if required.
 *
 * The cache validation and caching of the new attributes is done
 * atomically via the use of the mutex, r_statelock.  If required,
 * the cache invalidation is done atomically w.r.t. the cache
 * validation and caching of the attributes via the pseudo lock,
 * r_serial.
 *
 * This routine is used to do cache validation and attributes caching
 * for operations with a single set of post operation attributes.
 */

void
nfs4_attr_cache(vnode_t *vp, nfs4_ga_res_t *garp,
    hrtime_t t, cred_t *cr, int async,
    change_info4 *cinfo)
{
        rnode4_t *rp;
        int mtime_changed = 0;
        int ctime_changed = 0;
        vsecattr_t *vsp;
        int was_serial, set_time_cache_inval, recov;
        vattr_t *vap = &garp->n4g_va;
        mntinfo4_t *mi = VTOMI4(vp);
        len_t preattr_rsize;
        boolean_t writemodify_set = B_FALSE;
        boolean_t cachepurge_set = B_FALSE;

        ASSERT(mi->mi_vfsp->vfs_dev == garp->n4g_va.va_fsid);

        /* Is curthread the recovery thread? */
        mutex_enter(&mi->mi_lock);
        recov = (VTOMI4(vp)->mi_recovthread == curthread);
        mutex_exit(&mi->mi_lock);

        rp = VTOR4(vp);
        mutex_enter(&rp->r_statelock);
        was_serial = (rp->r_serial == curthread);
        if (rp->r_serial && !was_serial) {
                klwp_t *lwp = ttolwp(curthread);

                /*
                 * If we're the recovery thread, then purge current attrs
                 * and bail out to avoid potential deadlock between another
                 * thread caching attrs (r_serial thread), recov thread,
                 * and an async writer thread.
                 */
                if (recov) {
                        PURGE_ATTRCACHE4_LOCKED(rp);
                        mutex_exit(&rp->r_statelock);
                        return;
                }

                if (lwp != NULL)
                        lwp->lwp_nostop++;
                while (rp->r_serial != NULL) {
                        if (!cv_wait_sig(&rp->r_cv, &rp->r_statelock)) {
                                mutex_exit(&rp->r_statelock);
                                if (lwp != NULL)
                                        lwp->lwp_nostop--;
                                return;
                        }
                }
                if (lwp != NULL)
                        lwp->lwp_nostop--;
        }

        /*
         * If there is a page flush thread, the current thread needs to
         * bail out, to prevent a possible deadlock between the current
         * thread (which might be in a start_op/end_op region), the
         * recovery thread, and the page flush thread.  Expire the
         * attribute cache, so that any attributes the current thread was
         * going to set are not lost.
         */
        if ((rp->r_flags & R4PGFLUSH) && rp->r_pgflush != curthread) {
                PURGE_ATTRCACHE4_LOCKED(rp);
                mutex_exit(&rp->r_statelock);
                return;
        }

        if (rp->r_time_attr_saved > t) {
                /*
                 * Attributes have been cached since these attributes were
                 * probably made. If there is an inconsistency in what is
                 * cached, mark them invalid. If not, don't act on them.
                 */
                if (!CACHE4_VALID(rp, vap->va_mtime, vap->va_size))
                        PURGE_ATTRCACHE4_LOCKED(rp);
                mutex_exit(&rp->r_statelock);
                return;
        }
        set_time_cache_inval = 0;
        if (cinfo) {
                /*
                 * Only directory modifying callers pass non-NULL cinfo.
                 */
                ASSERT(vp->v_type == VDIR);
                /*
                 * If the cache timeout either doesn't exist or hasn't expired,
                 * and dir didn't changed on server before dirmod op
                 * and dir didn't change after dirmod op but before getattr
                 * then there's a chance that the client's cached data for
                 * this object is current (not stale).  No immediate cache
                 * flush is required.
                 *
                 */
                if ((! rp->r_time_cache_inval || t < rp->r_time_cache_inval) &&
                    cinfo->before == rp->r_change &&
                    (garp->n4g_change_valid &&
                    cinfo->after == garp->n4g_change)) {

                        /*
                         * If atomic isn't set, then the before/after info
                         * cannot be blindly trusted.  For this case, we tell
                         * nfs4_attrcache_va to cache the attrs but also
                         * establish an absolute maximum cache timeout.  When
                         * the timeout is reached, caches will be flushed.
                         */
                        if (! cinfo->atomic)
                                set_time_cache_inval = 1;
                } else {

                        /*
                         * We're not sure exactly what changed, but we know
                         * what to do.  flush all caches for dir.  remove the
                         * attr timeout.
                         *
                         * a) timeout expired.  flush all caches.
                         * b) r_change != cinfo.before.  flush all caches.
                         * c) r_change == cinfo.before, but cinfo.after !=
                         *    post-op getattr(change).  flush all caches.
                         * d) post-op getattr(change) not provided by server.
                         *    flush all caches.
                         */
                        mtime_changed = 1;
                        ctime_changed = 1;
                        rp->r_time_cache_inval = 0;
                }
        } else {
                /*
                 * Write thread after writing data to file on remote server,
                 * will always set R4WRITEMODIFIED to indicate that file on
                 * remote server was modified with a WRITE operation and would
                 * have marked attribute cache as timed out. If R4WRITEMODIFIED
                 * is set, then do not check for mtime and ctime change.
                 */
                if (!(rp->r_flags & R4WRITEMODIFIED)) {
                        if (!CACHE4_VALID(rp, vap->va_mtime, vap->va_size))
                                mtime_changed = 1;

                        if (rp->r_attr.va_ctime.tv_sec !=
                            vap->va_ctime.tv_sec ||
                            rp->r_attr.va_ctime.tv_nsec !=
                            vap->va_ctime.tv_nsec)
                                ctime_changed = 1;

                        /*
                         * If the change attribute was not provided by server
                         * or it differs, then flush all caches.
                         */
                        if (!garp->n4g_change_valid ||
                            rp->r_change != garp->n4g_change) {
                                mtime_changed = 1;
                                ctime_changed = 1;
                        }
                } else {
                        writemodify_set = B_TRUE;
                }
        }

        preattr_rsize = rp->r_size;

        nfs4_attrcache_va(vp, garp, set_time_cache_inval);

        /*
         * If we have updated filesize in nfs4_attrcache_va, as soon as we
         * drop statelock we will be in transition of purging all
         * our caches and updating them. It is possible for another
         * thread to pick this new file size and read in zeroed data.
         * stall other threads till cache purge is complete.
         */
        if ((!cinfo) && (rp->r_size != preattr_rsize)) {
                /*
                 * If R4WRITEMODIFIED was set and we have updated the file
                 * size, Server's returned file size need not necessarily
                 * be because of this Client's WRITE. We need to purge
                 * all caches.
                 */
                if (writemodify_set)
                        mtime_changed = 1;

                if (mtime_changed && !(rp->r_flags & R4INCACHEPURGE)) {
                        rp->r_flags |= R4INCACHEPURGE;
                        cachepurge_set = B_TRUE;
                }
        }

        if (!mtime_changed && !ctime_changed) {
                mutex_exit(&rp->r_statelock);
                return;
        }

        rp->r_serial = curthread;

        mutex_exit(&rp->r_statelock);

        /*
         * If we're the recov thread, then force async nfs4_purge_caches
         * to avoid potential deadlock.
         */
        if (mtime_changed)
                nfs4_purge_caches(vp, NFS4_NOPURGE_DNLC, cr, recov ? 1 : async);

        if ((rp->r_flags & R4INCACHEPURGE) && cachepurge_set) {
                mutex_enter(&rp->r_statelock);
                rp->r_flags &= ~R4INCACHEPURGE;
                cv_broadcast(&rp->r_cv);
                mutex_exit(&rp->r_statelock);
                cachepurge_set = B_FALSE;
        }

        if (ctime_changed) {
                (void) nfs4_access_purge_rp(rp);
                if (rp->r_secattr != NULL) {
                        mutex_enter(&rp->r_statelock);
                        vsp = rp->r_secattr;
                        rp->r_secattr = NULL;
                        mutex_exit(&rp->r_statelock);
                        if (vsp != NULL)
                                nfs4_acl_free_cache(vsp);
                }
        }

        if (!was_serial) {
                mutex_enter(&rp->r_statelock);
                rp->r_serial = NULL;
                cv_broadcast(&rp->r_cv);
                mutex_exit(&rp->r_statelock);
        }
}

/*
 * Set attributes cache for given vnode using virtual attributes.
 *
 * Set the timeout value on the attribute cache and fill it
 * with the passed in attributes.
 *
 * The caller must be holding r_statelock.
 */
static void
nfs4_attrcache_va(vnode_t *vp, nfs4_ga_res_t *garp, int set_cache_timeout)
{
        rnode4_t *rp;
        mntinfo4_t *mi;
        hrtime_t delta;
        hrtime_t now;
        vattr_t *vap = &garp->n4g_va;

        rp = VTOR4(vp);

        ASSERT(MUTEX_HELD(&rp->r_statelock));
        ASSERT(vap->va_mask == AT_ALL);

        /* Switch to master before checking v_flag */
        if (IS_SHADOW(vp, rp))
                vp = RTOV4(rp);

        now = gethrtime();

        mi = VTOMI4(vp);

        /*
         * Only establish a new cache timeout (if requested).  Never
         * extend a timeout.  Never clear a timeout.  Clearing a timeout
         * is done by nfs4_update_dircaches (ancestor in our call chain)
         */
        if (set_cache_timeout && ! rp->r_time_cache_inval)
                rp->r_time_cache_inval = now + mi->mi_acdirmax;

        /*
         * Delta is the number of nanoseconds that we will
         * cache the attributes of the file.  It is based on
         * the number of nanoseconds since the last time that
         * we detected a change.  The assumption is that files
         * that changed recently are likely to change again.
         * There is a minimum and a maximum for regular files
         * and for directories which is enforced though.
         *
         * Using the time since last change was detected
         * eliminates direct comparison or calculation
         * using mixed client and server times.  NFS does
         * not make any assumptions regarding the client
         * and server clocks being synchronized.
         */
        if (vap->va_mtime.tv_sec != rp->r_attr.va_mtime.tv_sec ||
            vap->va_mtime.tv_nsec != rp->r_attr.va_mtime.tv_nsec ||
            vap->va_size != rp->r_attr.va_size) {
                rp->r_time_attr_saved = now;
        }

        if ((mi->mi_flags & MI4_NOAC) || (vp->v_flag & VNOCACHE))
                delta = 0;
        else {
                delta = now - rp->r_time_attr_saved;
                if (vp->v_type == VDIR) {
                        if (delta < mi->mi_acdirmin)
                                delta = mi->mi_acdirmin;
                        else if (delta > mi->mi_acdirmax)
                                delta = mi->mi_acdirmax;
                } else {
                        if (delta < mi->mi_acregmin)
                                delta = mi->mi_acregmin;
                        else if (delta > mi->mi_acregmax)
                                delta = mi->mi_acregmax;
                }
        }
        rp->r_time_attr_inval = now + delta;

        rp->r_attr = *vap;
        if (garp->n4g_change_valid)
                rp->r_change = garp->n4g_change;

        /*
         * The attributes that were returned may be valid and can
         * be used, but they may not be allowed to be cached.
         * Reset the timers to cause immediate invalidation and
         * clear r_change so no VERIFY operations will suceed
         */
        if (garp->n4g_attrwhy == NFS4_GETATTR_NOCACHE_OK) {
                rp->r_time_attr_inval = now;
                rp->r_time_attr_saved = now;
                rp->r_change = 0;
        }

        /*
         * If mounted_on_fileid returned AND the object is a stub,
         * then set object's va_nodeid to the mounted over fid
         * returned by server.
         *
         * If mounted_on_fileid not provided/supported, then
         * just set it to 0 for now.  Eventually it would be
         * better to set it to a hashed version of FH.  This
         * would probably be good enough to provide a unique
         * fid/d_ino within a dir.
         *
         * We don't need to carry mounted_on_fileid in the
         * rnode as long as the client never requests fileid
         * without also requesting mounted_on_fileid.  For
         * now, it stays.
         */
        if (garp->n4g_mon_fid_valid) {
                rp->r_mntd_fid = garp->n4g_mon_fid;

                if (RP_ISSTUB(rp))
                        rp->r_attr.va_nodeid = rp->r_mntd_fid;
        }

        /*
         * Check to see if there are valid pathconf bits to
         * cache in the rnode.
         */
        if (garp->n4g_ext_res) {
                if (garp->n4g_ext_res->n4g_pc4.pc4_cache_valid) {
                        rp->r_pathconf = garp->n4g_ext_res->n4g_pc4;
                } else {
                        if (garp->n4g_ext_res->n4g_pc4.pc4_xattr_valid) {
                                rp->r_pathconf.pc4_xattr_valid = TRUE;
                                rp->r_pathconf.pc4_xattr_exists =
                                    garp->n4g_ext_res->n4g_pc4.pc4_xattr_exists;
                        }
                }
        }
        /*
         * Update the size of the file if there is no cached data or if
         * the cached data is clean and there is no data being written
         * out.
         */
        if (rp->r_size != vap->va_size &&
            (!vn_has_cached_data(vp) ||
            (!(rp->r_flags & R4DIRTY) && rp->r_count == 0))) {
                rp->r_size = vap->va_size;
        }
        nfs_setswaplike(vp, vap);
        rp->r_flags &= ~R4WRITEMODIFIED;
}

/*
 * Get attributes over-the-wire and update attributes cache
 * if no error occurred in the over-the-wire operation.
 * Return 0 if successful, otherwise error.
 */
int
nfs4_getattr_otw(vnode_t *vp, nfs4_ga_res_t *garp, cred_t *cr, int get_acl)
{
        mntinfo4_t *mi = VTOMI4(vp);
        hrtime_t t;
        nfs4_recov_state_t recov_state;
        nfs4_error_t e = { 0, NFS4_OK, RPC_SUCCESS };

        recov_state.rs_flags = 0;
        recov_state.rs_num_retry_despite_err = 0;

        /* Save the original mount point security flavor */
        (void) save_mnt_secinfo(mi->mi_curr_serv);

recov_retry:

        if ((e.error = nfs4_start_fop(mi, vp, NULL, OH_GETATTR,
            &recov_state, NULL))) {
                (void) check_mnt_secinfo(mi->mi_curr_serv, vp);
                return (e.error);
        }

        t = gethrtime();

        nfs4_getattr_otw_norecovery(vp, garp, &e, cr, get_acl);

        if (nfs4_needs_recovery(&e, FALSE, vp->v_vfsp)) {
                if (nfs4_start_recovery(&e, VTOMI4(vp), vp, NULL, NULL,
                    NULL, OP_GETATTR, NULL, NULL, NULL) == FALSE)  {
                        nfs4_end_fop(VTOMI4(vp), vp, NULL, OH_GETATTR,
                            &recov_state, 1);
                        goto recov_retry;
                }
        }

        nfs4_end_fop(VTOMI4(vp), vp, NULL, OH_GETATTR, &recov_state, 0);

        if (!e.error) {
                if (e.stat == NFS4_OK) {
                        nfs4_attr_cache(vp, garp, t, cr, FALSE, NULL);
                } else {
                        e.error = geterrno4(e.stat);

                        nfs4_purge_stale_fh(e.error, vp, cr);
                }
        }

        /*
         * If getattr a node that is a stub for a crossed
         * mount point, keep the original secinfo flavor for
         * the current file system, not the crossed one.
         */
        (void) check_mnt_secinfo(mi->mi_curr_serv, vp);

        return (e.error);
}

/*
 * Generate a compound to get attributes over-the-wire.
 */
void
nfs4_getattr_otw_norecovery(vnode_t *vp, nfs4_ga_res_t *garp,
    nfs4_error_t *ep, cred_t *cr, int get_acl)
{
        COMPOUND4args_clnt args;
        COMPOUND4res_clnt res;
        int doqueue;
        rnode4_t *rp = VTOR4(vp);
        nfs_argop4 argop[2];

        args.ctag = TAG_GETATTR;

        args.array_len = 2;
        args.array = argop;

        /* putfh */
        argop[0].argop = OP_CPUTFH;
        argop[0].nfs_argop4_u.opcputfh.sfh = rp->r_fh;

        /* getattr */
        /*
         * Unlike nfs version 2 and 3, where getattr returns all the
         * attributes, nfs version 4 returns only the ones explicitly
         * asked for. This creates problems, as some system functions
         * (e.g. cache check) require certain attributes and if the
         * cached node lacks some attributes such as uid/gid, it can
         * affect system utilities (e.g. "ls") that rely on the information
         * to be there. This can lead to anything from system crashes to
         * corrupted information processed by user apps.
         * So to ensure that all bases are covered, request at least
         * the AT_ALL attribute mask.
         */
        argop[1].argop = OP_GETATTR;
        argop[1].nfs_argop4_u.opgetattr.attr_request = NFS4_VATTR_MASK;
        if (get_acl)
                argop[1].nfs_argop4_u.opgetattr.attr_request |= FATTR4_ACL_MASK;
        argop[1].nfs_argop4_u.opgetattr.mi = VTOMI4(vp);

        doqueue = 1;

        rfs4call(VTOMI4(vp), &args, &res, cr, &doqueue, 0, ep);

        if (ep->error)
                return;

        if (res.status != NFS4_OK) {
                xdr_free(xdr_COMPOUND4res_clnt, (caddr_t)&res);
                return;
        }

        *garp = res.array[1].nfs_resop4_u.opgetattr.ga_res;

        xdr_free(xdr_COMPOUND4res_clnt, (caddr_t)&res);
}

/*
 * Return either cached or remote attributes. If get remote attr
 * use them to check and invalidate caches, then cache the new attributes.
 */
int
nfs4getattr(vnode_t *vp, vattr_t *vap, cred_t *cr)
{
        int error;
        rnode4_t *rp;
        nfs4_ga_res_t gar;

        ASSERT(nfs4_consistent_type(vp));

        /*
         * If we've got cached attributes, we're done, otherwise go
         * to the server to get attributes, which will update the cache
         * in the process. Either way, use the cached attributes for
         * the caller's vattr_t.
         *
         * Note that we ignore the gar set by the OTW call: the attr caching
         * code may make adjustments when storing to the rnode, and we want
         * to see those changes here.
         */
        rp = VTOR4(vp);
        error = 0;
        mutex_enter(&rp->r_statelock);
        if (!ATTRCACHE4_VALID(vp)) {
                mutex_exit(&rp->r_statelock);
                error = nfs4_getattr_otw(vp, &gar, cr, 0);
                mutex_enter(&rp->r_statelock);
        }

        if (!error)
                *vap = rp->r_attr;

        /* Return the client's view of file size */
        vap->va_size = rp->r_size;

        mutex_exit(&rp->r_statelock);

        ASSERT(nfs4_consistent_type(vp));

        return (error);
}

int
nfs4_attr_otw(vnode_t *vp, nfs4_tag_type_t tag_type,
    nfs4_ga_res_t *garp, bitmap4 reqbitmap, cred_t *cr)
{
        COMPOUND4args_clnt args;
        COMPOUND4res_clnt res;
        int doqueue;
        nfs_argop4 argop[2];
        mntinfo4_t *mi = VTOMI4(vp);
        bool_t needrecov = FALSE;
        nfs4_recov_state_t recov_state;
        nfs4_error_t e = { 0, NFS4_OK, RPC_SUCCESS };
        nfs4_ga_ext_res_t *gerp;

        recov_state.rs_flags = 0;
        recov_state.rs_num_retry_despite_err = 0;

recov_retry:
        args.ctag = tag_type;

        args.array_len = 2;
        args.array = argop;

        e.error = nfs4_start_fop(mi, vp, NULL, OH_GETATTR, &recov_state, NULL);
        if (e.error)
                return (e.error);

        /* putfh */
        argop[0].argop = OP_CPUTFH;
        argop[0].nfs_argop4_u.opcputfh.sfh = VTOR4(vp)->r_fh;

        /* getattr */
        argop[1].argop = OP_GETATTR;
        argop[1].nfs_argop4_u.opgetattr.attr_request = reqbitmap;
        argop[1].nfs_argop4_u.opgetattr.mi = mi;

        doqueue = 1;

        NFS4_DEBUG(nfs4_client_call_debug, (CE_NOTE,
            "nfs4_attr_otw: %s call, rp %s", needrecov ? "recov" : "first",
            rnode4info(VTOR4(vp))));

        rfs4call(mi, &args, &res, cr, &doqueue, 0, &e);

        needrecov = nfs4_needs_recovery(&e, FALSE, vp->v_vfsp);
        if (!needrecov && e.error) {
                nfs4_end_fop(VTOMI4(vp), vp, NULL, OH_GETATTR, &recov_state,
                    needrecov);
                return (e.error);
        }

        if (needrecov) {
                bool_t abort;

                NFS4_DEBUG(nfs4_client_recov_debug, (CE_NOTE,
                    "nfs4_attr_otw: initiating recovery\n"));

                abort = nfs4_start_recovery(&e, VTOMI4(vp), vp, NULL, NULL,
                    NULL, OP_GETATTR, NULL, NULL, NULL);
                nfs4_end_fop(VTOMI4(vp), vp, NULL, OH_GETATTR, &recov_state,
                    needrecov);
                if (!e.error) {
                        xdr_free(xdr_COMPOUND4res_clnt, (caddr_t)&res);
                        e.error = geterrno4(res.status);
                }
                if (abort == FALSE)
                        goto recov_retry;
                return (e.error);
        }

        if (res.status) {
                e.error = geterrno4(res.status);
        } else {
                gerp = garp->n4g_ext_res;
                bcopy(&res.array[1].nfs_resop4_u.opgetattr.ga_res,
                    garp, sizeof (nfs4_ga_res_t));
                garp->n4g_ext_res = gerp;
                if (garp->n4g_ext_res &&
                    res.array[1].nfs_resop4_u.opgetattr.ga_res.n4g_ext_res)
                        bcopy(res.array[1].nfs_resop4_u.opgetattr.
                            ga_res.n4g_ext_res,
                            garp->n4g_ext_res, sizeof (nfs4_ga_ext_res_t));
        }
        xdr_free(xdr_COMPOUND4res_clnt, (caddr_t)&res);
        nfs4_end_fop(VTOMI4(vp), vp, NULL, OH_GETATTR, &recov_state,
            needrecov);
        return (e.error);
}

/*
 * Asynchronous I/O parameters.  nfs_async_threads is the high-water mark
 * for the demand-based allocation of async threads per-mount.  The
 * nfs_async_timeout is the amount of time a thread will live after it
 * becomes idle, unless new I/O requests are received before the thread
 * dies.  See nfs4_async_putpage and nfs4_async_start.
 */

static void     nfs4_async_start(struct vfs *);
static void     nfs4_async_pgops_start(struct vfs *);
static void     nfs4_async_common_start(struct vfs *, int);

static void
free_async_args4(struct nfs4_async_reqs *args)
{
        rnode4_t *rp;

        if (args->a_io != NFS4_INACTIVE) {
                rp = VTOR4(args->a_vp);
                mutex_enter(&rp->r_statelock);
                rp->r_count--;
                if (args->a_io == NFS4_PUTAPAGE ||
                    args->a_io == NFS4_PAGEIO)
                        rp->r_awcount--;
                cv_broadcast(&rp->r_cv);
                mutex_exit(&rp->r_statelock);
                VN_RELE(args->a_vp);
        }
        crfree(args->a_cred);
        kmem_free(args, sizeof (*args));
}

/*
 * Cross-zone thread creation and NFS access is disallowed, yet fsflush() and
 * pageout(), running in the global zone, have legitimate reasons to do
 * fop_putpage(B_ASYNC) on other zones' NFS mounts.  We avoid the problem by
 * use of a a per-mount "asynchronous requests manager thread" which is
 * signaled by the various asynchronous work routines when there is
 * asynchronous work to be done.  It is responsible for creating new
 * worker threads if necessary, and notifying existing worker threads
 * that there is work to be done.
 *
 * In other words, it will "take the specifications from the customers and
 * give them to the engineers."
 *
 * Worker threads die off of their own accord if they are no longer
 * needed.
 *
 * This thread is killed when the zone is going away or the filesystem
 * is being unmounted.
 */
void
nfs4_async_manager(vfs_t *vfsp)
{
        callb_cpr_t cprinfo;
        mntinfo4_t *mi;
        uint_t max_threads;

        mi = VFTOMI4(vfsp);

        CALLB_CPR_INIT(&cprinfo, &mi->mi_async_lock, callb_generic_cpr,
            "nfs4_async_manager");

        mutex_enter(&mi->mi_async_lock);
        /*
         * We want to stash the max number of threads that this mount was
         * allowed so we can use it later when the variable is set to zero as
         * part of the zone/mount going away.
         *
         * We want to be able to create at least one thread to handle
         * asynchronous inactive calls.
         */
        max_threads = MAX(mi->mi_max_threads, 1);
        /*
         * We don't want to wait for mi_max_threads to go to zero, since that
         * happens as part of a failed unmount, but this thread should only
         * exit when the mount is really going away.
         *
         * Once MI4_ASYNC_MGR_STOP is set, no more async operations will be
         * attempted: the various _async_*() functions know to do things
         * inline if mi_max_threads == 0.  Henceforth we just drain out the
         * outstanding requests.
         *
         * Note that we still create zthreads even if we notice the zone is
         * shutting down (MI4_ASYNC_MGR_STOP is set); this may cause the zone
         * shutdown sequence to take slightly longer in some cases, but
         * doesn't violate the protocol, as all threads will exit as soon as
         * they're done processing the remaining requests.
         */
        for (;;) {
                while (mi->mi_async_req_count > 0) {
                        /*
                         * Paranoia: If the mount started out having
                         * (mi->mi_max_threads == 0), and the value was
                         * later changed (via a debugger or somesuch),
                         * we could be confused since we will think we
                         * can't create any threads, and the calling
                         * code (which looks at the current value of
                         * mi->mi_max_threads, now non-zero) thinks we
                         * can.
                         *
                         * So, because we're paranoid, we create threads
                         * up to the maximum of the original and the
                         * current value. This means that future
                         * (debugger-induced) alterations of
                         * mi->mi_max_threads are ignored for our
                         * purposes, but who told them they could change
                         * random values on a live kernel anyhow?
                         */
                        if (mi->mi_threads[NFS4_ASYNC_QUEUE] <
                            MAX(mi->mi_max_threads, max_threads)) {
                                mi->mi_threads[NFS4_ASYNC_QUEUE]++;
                                mutex_exit(&mi->mi_async_lock);
                                MI4_HOLD(mi);
                                VFS_HOLD(vfsp); /* hold for new thread */
                                (void) zthread_create(NULL, 0, nfs4_async_start,
                                    vfsp, 0, minclsyspri);
                                mutex_enter(&mi->mi_async_lock);
                        } else if (mi->mi_threads[NFS4_ASYNC_PGOPS_QUEUE] <
                            NUM_ASYNC_PGOPS_THREADS) {
                                mi->mi_threads[NFS4_ASYNC_PGOPS_QUEUE]++;
                                mutex_exit(&mi->mi_async_lock);
                                MI4_HOLD(mi);
                                VFS_HOLD(vfsp); /* hold for new thread */
                                (void) zthread_create(NULL, 0,
                                    nfs4_async_pgops_start, vfsp, 0,
                                    minclsyspri);
                                mutex_enter(&mi->mi_async_lock);
                        }
                        NFS4_WAKE_ASYNC_WORKER(mi->mi_async_work_cv);
                        ASSERT(mi->mi_async_req_count != 0);
                        mi->mi_async_req_count--;
                }

                mutex_enter(&mi->mi_lock);
                if (mi->mi_flags & MI4_ASYNC_MGR_STOP) {
                        mutex_exit(&mi->mi_lock);
                        break;
                }
                mutex_exit(&mi->mi_lock);

                CALLB_CPR_SAFE_BEGIN(&cprinfo);
                cv_wait(&mi->mi_async_reqs_cv, &mi->mi_async_lock);
                CALLB_CPR_SAFE_END(&cprinfo, &mi->mi_async_lock);
        }

        NFS4_DEBUG(nfs4_client_zone_debug, (CE_NOTE,
            "nfs4_async_manager exiting for vfs %p\n", (void *)mi->mi_vfsp));
        /*
         * Let everyone know we're done.
         */
        mi->mi_manager_thread = NULL;
        /*
         * Wake up the inactive thread.
         */
        cv_broadcast(&mi->mi_inact_req_cv);
        /*
         * Wake up anyone sitting in nfs4_async_manager_stop()
         */
        cv_broadcast(&mi->mi_async_cv);
        /*
         * There is no explicit call to mutex_exit(&mi->mi_async_lock)
         * since CALLB_CPR_EXIT is actually responsible for releasing
         * 'mi_async_lock'.
         */
        CALLB_CPR_EXIT(&cprinfo);
        VFS_RELE(vfsp); /* release thread's hold */
        MI4_RELE(mi);
        zthread_exit();
}

/*
 * Signal (and wait for) the async manager thread to clean up and go away.
 */
void
nfs4_async_manager_stop(vfs_t *vfsp)
{
        mntinfo4_t *mi = VFTOMI4(vfsp);

        mutex_enter(&mi->mi_async_lock);
        mutex_enter(&mi->mi_lock);
        mi->mi_flags |= MI4_ASYNC_MGR_STOP;
        mutex_exit(&mi->mi_lock);
        cv_broadcast(&mi->mi_async_reqs_cv);
        /*
         * Wait for the async manager thread to die.
         */
        while (mi->mi_manager_thread != NULL)
                cv_wait(&mi->mi_async_cv, &mi->mi_async_lock);
        mutex_exit(&mi->mi_async_lock);
}

int
nfs4_async_readahead(vnode_t *vp, uoff_t blkoff, caddr_t addr,
    struct seg *seg, cred_t *cr, void (*readahead)(vnode_t *,
    uoff_t, caddr_t, struct seg *, cred_t *))
{
        rnode4_t *rp;
        mntinfo4_t *mi;
        struct nfs4_async_reqs *args;

        rp = VTOR4(vp);
        ASSERT(rp->r_freef == NULL);

        mi = VTOMI4(vp);

        /*
         * If addr falls in a different segment, don't bother doing readahead.
         */
        if (addr >= seg->s_base + seg->s_size)
                return (-1);

        /*
         * If we can't allocate a request structure, punt on the readahead.
         */
        if ((args = kmem_alloc(sizeof (*args), KM_NOSLEEP)) == NULL)
                return (-1);

        /*
         * If a lock operation is pending, don't initiate any new
         * readaheads.  Otherwise, bump r_count to indicate the new
         * asynchronous I/O.
         */
        if (!nfs_rw_tryenter(&rp->r_lkserlock, RW_READER)) {
                kmem_free(args, sizeof (*args));
                return (-1);
        }
        mutex_enter(&rp->r_statelock);
        rp->r_count++;
        mutex_exit(&rp->r_statelock);
        nfs_rw_exit(&rp->r_lkserlock);

        args->a_next = NULL;
#ifdef DEBUG
        args->a_queuer = curthread;
#endif
        VN_HOLD(vp);
        args->a_vp = vp;
        ASSERT(cr != NULL);
        crhold(cr);
        args->a_cred = cr;
        args->a_io = NFS4_READ_AHEAD;
        args->a_nfs4_readahead = readahead;
        args->a_nfs4_blkoff = blkoff;
        args->a_nfs4_seg = seg;
        args->a_nfs4_addr = addr;

        mutex_enter(&mi->mi_async_lock);

        /*
         * If asyncio has been disabled, don't bother readahead.
         */
        if (mi->mi_max_threads == 0) {
                mutex_exit(&mi->mi_async_lock);
                goto noasync;
        }

        /*
         * Link request structure into the async list and
         * wakeup async thread to do the i/o.
         */
        if (mi->mi_async_reqs[NFS4_READ_AHEAD] == NULL) {
                mi->mi_async_reqs[NFS4_READ_AHEAD] = args;
                mi->mi_async_tail[NFS4_READ_AHEAD] = args;
        } else {
                mi->mi_async_tail[NFS4_READ_AHEAD]->a_next = args;
                mi->mi_async_tail[NFS4_READ_AHEAD] = args;
        }

        if (mi->mi_io_kstats) {
                mutex_enter(&mi->mi_lock);
                kstat_waitq_enter(KSTAT_IO_PTR(mi->mi_io_kstats));
                mutex_exit(&mi->mi_lock);
        }

        mi->mi_async_req_count++;
        ASSERT(mi->mi_async_req_count != 0);
        cv_signal(&mi->mi_async_reqs_cv);
        mutex_exit(&mi->mi_async_lock);
        return (0);

noasync:
        mutex_enter(&rp->r_statelock);
        rp->r_count--;
        cv_broadcast(&rp->r_cv);
        mutex_exit(&rp->r_statelock);
        VN_RELE(vp);
        crfree(cr);
        kmem_free(args, sizeof (*args));
        return (-1);
}

static void
nfs4_async_start(struct vfs *vfsp)
{
        nfs4_async_common_start(vfsp, NFS4_ASYNC_QUEUE);
}

static void
nfs4_async_pgops_start(struct vfs *vfsp)
{
        nfs4_async_common_start(vfsp, NFS4_ASYNC_PGOPS_QUEUE);
}

/*
 * The async queues for each mounted file system are arranged as a
 * set of queues, one for each async i/o type.  Requests are taken
 * from the queues in a round-robin fashion.  A number of consecutive
 * requests are taken from each queue before moving on to the next
 * queue.  This functionality may allow the NFS Version 2 server to do
 * write clustering, even if the client is mixing writes and reads
 * because it will take multiple write requests from the queue
 * before processing any of the other async i/o types.
 *
 * XXX The nfs4_async_common_start thread is unsafe in the light of the present
 * model defined by cpr to suspend the system. Specifically over the
 * wire calls are cpr-unsafe. The thread should be reevaluated in
 * case of future updates to the cpr model.
 */
static void
nfs4_async_common_start(struct vfs *vfsp, int async_queue)
{
        struct nfs4_async_reqs *args;
        mntinfo4_t *mi = VFTOMI4(vfsp);
        clock_t time_left = 1;
        callb_cpr_t cprinfo;
        int i;
        extern int nfs_async_timeout;
        int async_types;
        kcondvar_t *async_work_cv;

        if (async_queue == NFS4_ASYNC_QUEUE) {
                async_types = NFS4_ASYNC_TYPES;
                async_work_cv = &mi->mi_async_work_cv[NFS4_ASYNC_QUEUE];
        } else {
                async_types = NFS4_ASYNC_PGOPS_TYPES;
                async_work_cv = &mi->mi_async_work_cv[NFS4_ASYNC_PGOPS_QUEUE];
        }

        /*
         * Dynamic initialization of nfs_async_timeout to allow nfs to be
         * built in an implementation independent manner.
         */
        if (nfs_async_timeout == -1)
                nfs_async_timeout = NFS_ASYNC_TIMEOUT;

        CALLB_CPR_INIT(&cprinfo, &mi->mi_async_lock, callb_generic_cpr, "nas");

        mutex_enter(&mi->mi_async_lock);
        for (;;) {
                /*
                 * Find the next queue containing an entry.  We start
                 * at the current queue pointer and then round robin
                 * through all of them until we either find a non-empty
                 * queue or have looked through all of them.
                 */
                for (i = 0; i < async_types; i++) {
                        args = *mi->mi_async_curr[async_queue];
                        if (args != NULL)
                                break;
                        mi->mi_async_curr[async_queue]++;
                        if (mi->mi_async_curr[async_queue] ==
                            &mi->mi_async_reqs[async_types]) {
                                mi->mi_async_curr[async_queue] =
                                    &mi->mi_async_reqs[0];
                        }
                }
                /*
                 * If we didn't find a entry, then block until woken up
                 * again and then look through the queues again.
                 */
                if (args == NULL) {
                        /*
                         * Exiting is considered to be safe for CPR as well
                         */
                        CALLB_CPR_SAFE_BEGIN(&cprinfo);

                        /*
                         * Wakeup thread waiting to unmount the file
                         * system only if all async threads are inactive.
                         *
                         * If we've timed-out and there's nothing to do,
                         * then get rid of this thread.
                         */
                        if (mi->mi_max_threads == 0 || time_left <= 0) {
                                --mi->mi_threads[async_queue];

                                if (mi->mi_threads[NFS4_ASYNC_QUEUE] == 0 &&
                                    mi->mi_threads[NFS4_ASYNC_PGOPS_QUEUE] == 0)
                                        cv_signal(&mi->mi_async_cv);
                                CALLB_CPR_EXIT(&cprinfo);
                                VFS_RELE(vfsp); /* release thread's hold */
                                MI4_RELE(mi);
                                zthread_exit();
                                /* NOTREACHED */
                        }
                        time_left = cv_reltimedwait(async_work_cv,
                            &mi->mi_async_lock, nfs_async_timeout,
                            TR_CLOCK_TICK);

                        CALLB_CPR_SAFE_END(&cprinfo, &mi->mi_async_lock);

                        continue;
                } else {
                        time_left = 1;
                }

                /*
                 * Remove the request from the async queue and then
                 * update the current async request queue pointer.  If
                 * the current queue is empty or we have removed enough
                 * consecutive entries from it, then reset the counter
                 * for this queue and then move the current pointer to
                 * the next queue.
                 */
                *mi->mi_async_curr[async_queue] = args->a_next;
                if (*mi->mi_async_curr[async_queue] == NULL ||
                    --mi->mi_async_clusters[args->a_io] == 0) {
                        mi->mi_async_clusters[args->a_io] =
                            mi->mi_async_init_clusters;
                        mi->mi_async_curr[async_queue]++;
                        if (mi->mi_async_curr[async_queue] ==
                            &mi->mi_async_reqs[async_types]) {
                                mi->mi_async_curr[async_queue] =
                                    &mi->mi_async_reqs[0];
                        }
                }

                if (args->a_io != NFS4_INACTIVE && mi->mi_io_kstats) {
                        mutex_enter(&mi->mi_lock);
                        kstat_waitq_exit(KSTAT_IO_PTR(mi->mi_io_kstats));
                        mutex_exit(&mi->mi_lock);
                }

                mutex_exit(&mi->mi_async_lock);

                /*
                 * Obtain arguments from the async request structure.
                 */
                if (args->a_io == NFS4_READ_AHEAD && mi->mi_max_threads > 0) {
                        (*args->a_nfs4_readahead)(args->a_vp,
                            args->a_nfs4_blkoff, args->a_nfs4_addr,
                            args->a_nfs4_seg, args->a_cred);
                } else if (args->a_io == NFS4_PUTAPAGE) {
                        (void) (*args->a_nfs4_putapage)(args->a_vp,
                            args->a_nfs4_pp, args->a_nfs4_off,
                            args->a_nfs4_len, args->a_nfs4_flags,
                            args->a_cred);
                } else if (args->a_io == NFS4_PAGEIO) {
                        (void) (*args->a_nfs4_pageio)(args->a_vp,
                            args->a_nfs4_pp, args->a_nfs4_off,
                            args->a_nfs4_len, args->a_nfs4_flags,
                            args->a_cred);
                } else if (args->a_io == NFS4_READDIR) {
                        (void) ((*args->a_nfs4_readdir)(args->a_vp,
                            args->a_nfs4_rdc, args->a_cred));
                } else if (args->a_io == NFS4_COMMIT) {
                        (*args->a_nfs4_commit)(args->a_vp, args->a_nfs4_plist,
                            args->a_nfs4_offset, args->a_nfs4_count,
                            args->a_cred);
                } else if (args->a_io == NFS4_INACTIVE) {
                        nfs4_inactive_otw(args->a_vp, args->a_cred);
                }

                /*
                 * Now, release the vnode and free the credentials
                 * structure.
                 */
                free_async_args4(args);
                /*
                 * Reacquire the mutex because it will be needed above.
                 */
                mutex_enter(&mi->mi_async_lock);
        }
}

/*
 * nfs4_inactive_thread - look for vnodes that need over-the-wire calls as
 * part of fop_inactive.
 */

void
nfs4_inactive_thread(mntinfo4_t *mi)
{
        struct nfs4_async_reqs *args;
        callb_cpr_t cprinfo;
        vfs_t *vfsp = mi->mi_vfsp;

        CALLB_CPR_INIT(&cprinfo, &mi->mi_async_lock, callb_generic_cpr,
            "nfs4_inactive_thread");

        for (;;) {
                mutex_enter(&mi->mi_async_lock);
                args = mi->mi_async_reqs[NFS4_INACTIVE];
                if (args == NULL) {
                        mutex_enter(&mi->mi_lock);
                        /*
                         * We don't want to exit until the async manager is done
                         * with its work; hence the check for mi_manager_thread
                         * being NULL.
                         *
                         * The async manager thread will cv_broadcast() on
                         * mi_inact_req_cv when it's done, at which point we'll
                         * wake up and exit.
                         */
                        if (mi->mi_manager_thread == NULL)
                                goto die;
                        mi->mi_flags |= MI4_INACTIVE_IDLE;
                        mutex_exit(&mi->mi_lock);
                        cv_signal(&mi->mi_async_cv);
                        CALLB_CPR_SAFE_BEGIN(&cprinfo);
                        cv_wait(&mi->mi_inact_req_cv, &mi->mi_async_lock);
                        CALLB_CPR_SAFE_END(&cprinfo, &mi->mi_async_lock);
                        mutex_exit(&mi->mi_async_lock);
                } else {
                        mutex_enter(&mi->mi_lock);
                        mi->mi_flags &= ~MI4_INACTIVE_IDLE;
                        mutex_exit(&mi->mi_lock);
                        mi->mi_async_reqs[NFS4_INACTIVE] = args->a_next;
                        mutex_exit(&mi->mi_async_lock);
                        nfs4_inactive_otw(args->a_vp, args->a_cred);
                        crfree(args->a_cred);
                        kmem_free(args, sizeof (*args));
                }
        }
die:
        mutex_exit(&mi->mi_lock);
        mi->mi_inactive_thread = NULL;
        cv_signal(&mi->mi_async_cv);

        /*
         * There is no explicit call to mutex_exit(&mi->mi_async_lock) since
         * CALLB_CPR_EXIT is actually responsible for releasing 'mi_async_lock'.
         */
        CALLB_CPR_EXIT(&cprinfo);

        NFS4_DEBUG(nfs4_client_zone_debug, (CE_NOTE,
            "nfs4_inactive_thread exiting for vfs %p\n", (void *)vfsp));

        MI4_RELE(mi);
        zthread_exit();
        /* NOTREACHED */
}

/*
 * nfs_async_stop:
 * Wait for all outstanding putpage operations and the inactive thread to
 * complete; nfs4_async_stop_sig() without interruptibility.
 */
void
nfs4_async_stop(struct vfs *vfsp)
{
        mntinfo4_t *mi = VFTOMI4(vfsp);

        /*
         * Wait for all outstanding async operations to complete and for
         * worker threads to exit.
         */
        mutex_enter(&mi->mi_async_lock);
        mi->mi_max_threads = 0;
        NFS4_WAKEALL_ASYNC_WORKERS(mi->mi_async_work_cv);
        while (mi->mi_threads[NFS4_ASYNC_QUEUE] != 0 ||
            mi->mi_threads[NFS4_ASYNC_PGOPS_QUEUE] != 0)
                cv_wait(&mi->mi_async_cv, &mi->mi_async_lock);

        /*
         * Wait for the inactive thread to finish doing what it's doing.  It
         * won't exit until the last reference to the vfs_t goes away.
         */
        if (mi->mi_inactive_thread != NULL) {
                mutex_enter(&mi->mi_lock);
                while (!(mi->mi_flags & MI4_INACTIVE_IDLE) ||
                    (mi->mi_async_reqs[NFS4_INACTIVE] != NULL)) {
                        mutex_exit(&mi->mi_lock);
                        cv_wait(&mi->mi_async_cv, &mi->mi_async_lock);
                        mutex_enter(&mi->mi_lock);
                }
                mutex_exit(&mi->mi_lock);
        }
        mutex_exit(&mi->mi_async_lock);
}

/*
 * nfs_async_stop_sig:
 * Wait for all outstanding putpage operations and the inactive thread to
 * complete. If a signal is delivered we will abort and return non-zero;
 * otherwise return 0. Since this routine is called from nfs4_unmount, we
 * need to make it interruptible.
 */
int
nfs4_async_stop_sig(struct vfs *vfsp)
{
        mntinfo4_t *mi = VFTOMI4(vfsp);
        ushort_t omax;
        bool_t intr = FALSE;

        /*
         * Wait for all outstanding putpage operations to complete and for
         * worker threads to exit.
         */
        mutex_enter(&mi->mi_async_lock);
        omax = mi->mi_max_threads;
        mi->mi_max_threads = 0;
        NFS4_WAKEALL_ASYNC_WORKERS(mi->mi_async_work_cv);
        while (mi->mi_threads[NFS4_ASYNC_QUEUE] != 0 ||
            mi->mi_threads[NFS4_ASYNC_PGOPS_QUEUE] != 0) {
                if (!cv_wait_sig(&mi->mi_async_cv, &mi->mi_async_lock)) {
                        intr = TRUE;
                        goto interrupted;
                }
        }

        /*
         * Wait for the inactive thread to finish doing what it's doing.  It
         * won't exit until the a last reference to the vfs_t goes away.
         */
        if (mi->mi_inactive_thread != NULL) {
                mutex_enter(&mi->mi_lock);
                while (!(mi->mi_flags & MI4_INACTIVE_IDLE) ||
                    (mi->mi_async_reqs[NFS4_INACTIVE] != NULL)) {
                        mutex_exit(&mi->mi_lock);
                        if (!cv_wait_sig(&mi->mi_async_cv,
                            &mi->mi_async_lock)) {
                                intr = TRUE;
                                goto interrupted;
                        }
                        mutex_enter(&mi->mi_lock);
                }
                mutex_exit(&mi->mi_lock);
        }
interrupted:
        if (intr)
                mi->mi_max_threads = omax;
        mutex_exit(&mi->mi_async_lock);

        return (intr);
}

int
nfs4_async_putapage(vnode_t *vp, page_t *pp, uoff_t off, size_t len,
    int flags, cred_t *cr, int (*putapage)(vnode_t *, page_t *,
    uoff_t, size_t, int, cred_t *))
{
        rnode4_t *rp;
        mntinfo4_t *mi;
        struct nfs4_async_reqs *args;

        ASSERT(flags & B_ASYNC);
        ASSERT(vp->v_vfsp != NULL);

        rp = VTOR4(vp);
        ASSERT(rp->r_count > 0);

        mi = VTOMI4(vp);

        /*
         * If we can't allocate a request structure, do the putpage
         * operation synchronously in this thread's context.
         */
        if ((args = kmem_alloc(sizeof (*args), KM_NOSLEEP)) == NULL)
                goto noasync;

        args->a_next = NULL;
#ifdef DEBUG
        args->a_queuer = curthread;
#endif
        VN_HOLD(vp);
        args->a_vp = vp;
        ASSERT(cr != NULL);
        crhold(cr);
        args->a_cred = cr;
        args->a_io = NFS4_PUTAPAGE;
        args->a_nfs4_putapage = putapage;
        args->a_nfs4_pp = pp;
        args->a_nfs4_off = off;
        args->a_nfs4_len = (uint_t)len;
        args->a_nfs4_flags = flags;

        mutex_enter(&mi->mi_async_lock);

        /*
         * If asyncio has been disabled, then make a synchronous request.
         * This check is done a second time in case async io was diabled
         * while this thread was blocked waiting for memory pressure to
         * reduce or for the queue to drain.
         */
        if (mi->mi_max_threads == 0) {
                mutex_exit(&mi->mi_async_lock);

                VN_RELE(vp);
                crfree(cr);
                kmem_free(args, sizeof (*args));
                goto noasync;
        }

        /*
         * Link request structure into the async list and
         * wakeup async thread to do the i/o.
         */
        if (mi->mi_async_reqs[NFS4_PUTAPAGE] == NULL) {
                mi->mi_async_reqs[NFS4_PUTAPAGE] = args;
                mi->mi_async_tail[NFS4_PUTAPAGE] = args;
        } else {
                mi->mi_async_tail[NFS4_PUTAPAGE]->a_next = args;
                mi->mi_async_tail[NFS4_PUTAPAGE] = args;
        }

        mutex_enter(&rp->r_statelock);
        rp->r_count++;
        rp->r_awcount++;
        mutex_exit(&rp->r_statelock);

        if (mi->mi_io_kstats) {
                mutex_enter(&mi->mi_lock);
                kstat_waitq_enter(KSTAT_IO_PTR(mi->mi_io_kstats));
                mutex_exit(&mi->mi_lock);
        }

        mi->mi_async_req_count++;
        ASSERT(mi->mi_async_req_count != 0);
        cv_signal(&mi->mi_async_reqs_cv);
        mutex_exit(&mi->mi_async_lock);
        return (0);

noasync:

        if (curproc == proc_pageout || curproc == proc_fsflush) {
                /*
                 * If we get here in the context of the pageout/fsflush,
                 * or we have run out of memory or we're attempting to
                 * unmount we refuse to do a sync write, because this may
                 * hang pageout/fsflush and the machine. In this case,
                 * we just re-mark the page as dirty and punt on the page.
                 *
                 * Make sure B_FORCE isn't set.  We can re-mark the
                 * pages as dirty and unlock the pages in one swoop by
                 * passing in B_ERROR to pvn_write_done().  However,
                 * we should make sure B_FORCE isn't set - we don't
                 * want the page tossed before it gets written out.
                 */
                if (flags & B_FORCE)
                        flags &= ~(B_INVAL | B_FORCE);
                pvn_write_done(pp, flags | B_ERROR);
                return (0);
        }

        if (nfs_zone() != mi->mi_zone) {
                /*
                 * So this was a cross-zone sync putpage.
                 *
                 * We pass in B_ERROR to pvn_write_done() to re-mark the pages
                 * as dirty and unlock them.
                 *
                 * We don't want to clear B_FORCE here as the caller presumably
                 * knows what they're doing if they set it.
                 */
                pvn_write_done(pp, flags | B_ERROR);
                return (EPERM);
        }
        return ((*putapage)(vp, pp, off, len, flags, cr));
}

int
nfs4_async_pageio(vnode_t *vp, page_t *pp, uoff_t io_off, size_t io_len,
    int flags, cred_t *cr, int (*pageio)(vnode_t *, page_t *, uoff_t,
    size_t, int, cred_t *))
{
        rnode4_t *rp;
        mntinfo4_t *mi;
        struct nfs4_async_reqs *args;

        ASSERT(flags & B_ASYNC);
        ASSERT(vp->v_vfsp != NULL);

        rp = VTOR4(vp);
        ASSERT(rp->r_count > 0);

        mi = VTOMI4(vp);

        /*
         * If we can't allocate a request structure, do the pageio
         * request synchronously in this thread's context.
         */
        if ((args = kmem_alloc(sizeof (*args), KM_NOSLEEP)) == NULL)
                goto noasync;

        args->a_next = NULL;
#ifdef DEBUG
        args->a_queuer = curthread;
#endif
        VN_HOLD(vp);
        args->a_vp = vp;
        ASSERT(cr != NULL);
        crhold(cr);
        args->a_cred = cr;
        args->a_io = NFS4_PAGEIO;
        args->a_nfs4_pageio = pageio;
        args->a_nfs4_pp = pp;
        args->a_nfs4_off = io_off;
        args->a_nfs4_len = (uint_t)io_len;
        args->a_nfs4_flags = flags;

        mutex_enter(&mi->mi_async_lock);

        /*
         * If asyncio has been disabled, then make a synchronous request.
         * This check is done a second time in case async io was diabled
         * while this thread was blocked waiting for memory pressure to
         * reduce or for the queue to drain.
         */
        if (mi->mi_max_threads == 0) {
                mutex_exit(&mi->mi_async_lock);

                VN_RELE(vp);
                crfree(cr);
                kmem_free(args, sizeof (*args));
                goto noasync;
        }

        /*
         * Link request structure into the async list and
         * wakeup async thread to do the i/o.
         */
        if (mi->mi_async_reqs[NFS4_PAGEIO] == NULL) {
                mi->mi_async_reqs[NFS4_PAGEIO] = args;
                mi->mi_async_tail[NFS4_PAGEIO] = args;
        } else {
                mi->mi_async_tail[NFS4_PAGEIO]->a_next = args;
                mi->mi_async_tail[NFS4_PAGEIO] = args;
        }

        mutex_enter(&rp->r_statelock);
        rp->r_count++;
        rp->r_awcount++;
        mutex_exit(&rp->r_statelock);

        if (mi->mi_io_kstats) {
                mutex_enter(&mi->mi_lock);
                kstat_waitq_enter(KSTAT_IO_PTR(mi->mi_io_kstats));
                mutex_exit(&mi->mi_lock);
        }

        mi->mi_async_req_count++;
        ASSERT(mi->mi_async_req_count != 0);
        cv_signal(&mi->mi_async_reqs_cv);
        mutex_exit(&mi->mi_async_lock);
        return (0);

noasync:
        /*
         * If we can't do it ASYNC, for reads we do nothing (but cleanup
         * the page list), for writes we do it synchronously, except for
         * proc_pageout/proc_fsflush as described below.
         */
        if (flags & B_READ) {
                pvn_read_done(pp, flags | B_ERROR);
                return (0);
        }

        if (curproc == proc_pageout || curproc == proc_fsflush) {
                /*
                 * If we get here in the context of the pageout/fsflush,
                 * we refuse to do a sync write, because this may hang
                 * pageout/fsflush (and the machine). In this case, we just
                 * re-mark the page as dirty and punt on the page.
                 *
                 * Make sure B_FORCE isn't set.  We can re-mark the
                 * pages as dirty and unlock the pages in one swoop by
                 * passing in B_ERROR to pvn_write_done().  However,
                 * we should make sure B_FORCE isn't set - we don't
                 * want the page tossed before it gets written out.
                 */
                if (flags & B_FORCE)
                        flags &= ~(B_INVAL | B_FORCE);
                pvn_write_done(pp, flags | B_ERROR);
                return (0);
        }

        if (nfs_zone() != mi->mi_zone) {
                /*
                 * So this was a cross-zone sync pageio.  We pass in B_ERROR
                 * to pvn_write_done() to re-mark the pages as dirty and unlock
                 * them.
                 *
                 * We don't want to clear B_FORCE here as the caller presumably
                 * knows what they're doing if they set it.
                 */
                pvn_write_done(pp, flags | B_ERROR);
                return (EPERM);
        }
        return ((*pageio)(vp, pp, io_off, io_len, flags, cr));
}

void
nfs4_async_readdir(vnode_t *vp, rddir4_cache *rdc, cred_t *cr,
    int (*readdir)(vnode_t *, rddir4_cache *, cred_t *))
{
        rnode4_t *rp;
        mntinfo4_t *mi;
        struct nfs4_async_reqs *args;

        rp = VTOR4(vp);
        ASSERT(rp->r_freef == NULL);

        mi = VTOMI4(vp);

        /*
         * If we can't allocate a request structure, skip the readdir.
         */
        if ((args = kmem_alloc(sizeof (*args), KM_NOSLEEP)) == NULL)
                goto noasync;

        args->a_next = NULL;
#ifdef DEBUG
        args->a_queuer = curthread;
#endif
        VN_HOLD(vp);
        args->a_vp = vp;
        ASSERT(cr != NULL);
        crhold(cr);
        args->a_cred = cr;
        args->a_io = NFS4_READDIR;
        args->a_nfs4_readdir = readdir;
        args->a_nfs4_rdc = rdc;

        mutex_enter(&mi->mi_async_lock);

        /*
         * If asyncio has been disabled, then skip this request
         */
        if (mi->mi_max_threads == 0) {
                mutex_exit(&mi->mi_async_lock);

                VN_RELE(vp);
                crfree(cr);
                kmem_free(args, sizeof (*args));
                goto noasync;
        }

        /*
         * Link request structure into the async list and
         * wakeup async thread to do the i/o.
         */
        if (mi->mi_async_reqs[NFS4_READDIR] == NULL) {
                mi->mi_async_reqs[NFS4_READDIR] = args;
                mi->mi_async_tail[NFS4_READDIR] = args;
        } else {
                mi->mi_async_tail[NFS4_READDIR]->a_next = args;
                mi->mi_async_tail[NFS4_READDIR] = args;
        }

        mutex_enter(&rp->r_statelock);
        rp->r_count++;
        mutex_exit(&rp->r_statelock);

        if (mi->mi_io_kstats) {
                mutex_enter(&mi->mi_lock);
                kstat_waitq_enter(KSTAT_IO_PTR(mi->mi_io_kstats));
                mutex_exit(&mi->mi_lock);
        }

        mi->mi_async_req_count++;
        ASSERT(mi->mi_async_req_count != 0);
        cv_signal(&mi->mi_async_reqs_cv);
        mutex_exit(&mi->mi_async_lock);
        return;

noasync:
        mutex_enter(&rp->r_statelock);
        rdc->entries = NULL;
        /*
         * Indicate that no one is trying to fill this entry and
         * it still needs to be filled.
         */
        rdc->flags &= ~RDDIR;
        rdc->flags |= RDDIRREQ;
        rddir4_cache_rele(rp, rdc);
        mutex_exit(&rp->r_statelock);
}

void
nfs4_async_commit(vnode_t *vp, page_t *plist, offset3 offset, count3 count,
    cred_t *cr, void (*commit)(vnode_t *, page_t *, offset3, count3,
    cred_t *))
{
        rnode4_t *rp;
        mntinfo4_t *mi;
        struct nfs4_async_reqs *args;
        page_t *pp;

        rp = VTOR4(vp);
        mi = VTOMI4(vp);

        /*
         * If we can't allocate a request structure, do the commit
         * operation synchronously in this thread's context.
         */
        if ((args = kmem_alloc(sizeof (*args), KM_NOSLEEP)) == NULL)
                goto noasync;

        args->a_next = NULL;
#ifdef DEBUG
        args->a_queuer = curthread;
#endif
        VN_HOLD(vp);
        args->a_vp = vp;
        ASSERT(cr != NULL);
        crhold(cr);
        args->a_cred = cr;
        args->a_io = NFS4_COMMIT;
        args->a_nfs4_commit = commit;
        args->a_nfs4_plist = plist;
        args->a_nfs4_offset = offset;
        args->a_nfs4_count = count;

        mutex_enter(&mi->mi_async_lock);

        /*
         * If asyncio has been disabled, then make a synchronous request.
         * This check is done a second time in case async io was diabled
         * while this thread was blocked waiting for memory pressure to
         * reduce or for the queue to drain.
         */
        if (mi->mi_max_threads == 0) {
                mutex_exit(&mi->mi_async_lock);

                VN_RELE(vp);
                crfree(cr);
                kmem_free(args, sizeof (*args));
                goto noasync;
        }

        /*
         * Link request structure into the async list and
         * wakeup async thread to do the i/o.
         */
        if (mi->mi_async_reqs[NFS4_COMMIT] == NULL) {
                mi->mi_async_reqs[NFS4_COMMIT] = args;
                mi->mi_async_tail[NFS4_COMMIT] = args;
        } else {
                mi->mi_async_tail[NFS4_COMMIT]->a_next = args;
                mi->mi_async_tail[NFS4_COMMIT] = args;
        }

        mutex_enter(&rp->r_statelock);
        rp->r_count++;
        mutex_exit(&rp->r_statelock);

        if (mi->mi_io_kstats) {
                mutex_enter(&mi->mi_lock);
                kstat_waitq_enter(KSTAT_IO_PTR(mi->mi_io_kstats));
                mutex_exit(&mi->mi_lock);
        }

        mi->mi_async_req_count++;
        ASSERT(mi->mi_async_req_count != 0);
        cv_signal(&mi->mi_async_reqs_cv);
        mutex_exit(&mi->mi_async_lock);
        return;

noasync:
        if (curproc == proc_pageout || curproc == proc_fsflush ||
            nfs_zone() != mi->mi_zone) {
                while (plist != NULL) {
                        pp = plist;
                        page_sub(&plist, pp);
                        pp->p_fsdata = C_COMMIT;
                        page_unlock(pp);
                }
                return;
        }
        (*commit)(vp, plist, offset, count, cr);
}

/*
 * nfs4_async_inactive - hand off a fop_inactive call to a thread.  The
 * reference to the vnode is handed over to the thread; the caller should
 * no longer refer to the vnode.
 *
 * Unlike most of the async routines, this handoff is needed for
 * correctness reasons, not just performance.  So doing operations in the
 * context of the current thread is not an option.
 */
void
nfs4_async_inactive(vnode_t *vp, cred_t *cr)
{
        mntinfo4_t *mi;
        struct nfs4_async_reqs *args;
        boolean_t signal_inactive_thread = B_FALSE;

        mi = VTOMI4(vp);

        args = kmem_alloc(sizeof (*args), KM_SLEEP);
        args->a_next = NULL;
#ifdef DEBUG
        args->a_queuer = curthread;
#endif
        args->a_vp = vp;
        ASSERT(cr != NULL);
        crhold(cr);
        args->a_cred = cr;
        args->a_io = NFS4_INACTIVE;

        /*
         * Note that we don't check mi->mi_max_threads here, since we
         * *need* to get rid of this vnode regardless of whether someone
         * set nfs4_max_threads to zero in /etc/system.
         *
         * The manager thread knows about this and is willing to create
         * at least one thread to accommodate us.
         */
        mutex_enter(&mi->mi_async_lock);
        if (mi->mi_inactive_thread == NULL) {
                rnode4_t *rp;
                vnode_t *unldvp = NULL;
                char *unlname;
                cred_t *unlcred;

                mutex_exit(&mi->mi_async_lock);
                /*
                 * We just need to free up the memory associated with the
                 * vnode, which can be safely done from within the current
                 * context.
                 */
                crfree(cr);     /* drop our reference */
                kmem_free(args, sizeof (*args));
                rp = VTOR4(vp);
                mutex_enter(&rp->r_statelock);
                if (rp->r_unldvp != NULL) {
                        unldvp = rp->r_unldvp;
                        rp->r_unldvp = NULL;
                        unlname = rp->r_unlname;
                        rp->r_unlname = NULL;
                        unlcred = rp->r_unlcred;
                        rp->r_unlcred = NULL;
                }
                mutex_exit(&rp->r_statelock);
                /*
                 * No need to explicitly throw away any cached pages.  The
                 * eventual r4inactive() will attempt a synchronous
                 * fop_putpage() which will immediately fail since the request
                 * is coming from the wrong zone, and then will proceed to call
                 * nfs4_invalidate_pages() which will clean things up for us.
                 *
                 * Throw away the delegation here so rp4_addfree()'s attempt to
                 * return any existing delegations becomes a no-op.
                 */
                if (rp->r_deleg_type != OPEN_DELEGATE_NONE) {
                        (void) nfs_rw_enter_sig(&mi->mi_recovlock, RW_READER,
                            FALSE);
                        (void) nfs4delegreturn(rp, NFS4_DR_DISCARD);
                        nfs_rw_exit(&mi->mi_recovlock);
                }
                nfs4_clear_open_streams(rp);

                rp4_addfree(rp, cr);
                if (unldvp != NULL) {
                        kmem_free(unlname, MAXNAMELEN);
                        VN_RELE(unldvp);
                        crfree(unlcred);
                }
                return;
        }

        if (mi->mi_manager_thread == NULL) {
                /*
                 * We want to talk to the inactive thread.
                 */
                signal_inactive_thread = B_TRUE;
        }

        /*
         * Enqueue the vnode and wake up either the special thread (empty
         * list) or an async thread.
         */
        if (mi->mi_async_reqs[NFS4_INACTIVE] == NULL) {
                mi->mi_async_reqs[NFS4_INACTIVE] = args;
                mi->mi_async_tail[NFS4_INACTIVE] = args;
                signal_inactive_thread = B_TRUE;
        } else {
                mi->mi_async_tail[NFS4_INACTIVE]->a_next = args;
                mi->mi_async_tail[NFS4_INACTIVE] = args;
        }
        if (signal_inactive_thread) {
                cv_signal(&mi->mi_inact_req_cv);
        } else  {
                mi->mi_async_req_count++;
                ASSERT(mi->mi_async_req_count != 0);
                cv_signal(&mi->mi_async_reqs_cv);
        }

        mutex_exit(&mi->mi_async_lock);
}

int
writerp4(rnode4_t *rp, caddr_t base, int tcount, struct uio *uio, int pgcreated)
{
        int pagecreate;
        int n;
        int saved_n;
        caddr_t saved_base;
        uoff_t offset;
        int error;
        int sm_error;
        vnode_t *vp = RTOV(rp);

        ASSERT(tcount <= MAXBSIZE && tcount <= uio->uio_resid);
        ASSERT(nfs_rw_lock_held(&rp->r_rwlock, RW_WRITER));
        if (!vpm_enable) {
                ASSERT(((uintptr_t)base & MAXBOFFSET) + tcount <= MAXBSIZE);
        }

        /*
         * Move bytes in at most PAGESIZE chunks. We must avoid
         * spanning pages in uiomove() because page faults may cause
         * the cache to be invalidated out from under us. The r_size is not
         * updated until after the uiomove. If we push the last page of a
         * file before r_size is correct, we will lose the data written past
         * the current (and invalid) r_size.
         */
        do {
                offset = uio->uio_loffset;
                pagecreate = 0;

                /*
                 * n is the number of bytes required to satisfy the request
                 *   or the number of bytes to fill out the page.
                 */
                n = (int)MIN((PAGESIZE - (offset & PAGEOFFSET)), tcount);

                /*
                 * Check to see if we can skip reading in the page
                 * and just allocate the memory.  We can do this
                 * if we are going to rewrite the entire mapping
                 * or if we are going to write to or beyond the current
                 * end of file from the beginning of the mapping.
                 *
                 * The read of r_size is now protected by r_statelock.
                 */
                mutex_enter(&rp->r_statelock);
                /*
                 * When pgcreated is nonzero the caller has already done
                 * a segmap_getmapflt with forcefault 0 and S_WRITE. With
                 * segkpm this means we already have at least one page
                 * created and mapped at base.
                 */
                pagecreate = pgcreated ||
                    ((offset & PAGEOFFSET) == 0 &&
                    (n == PAGESIZE || ((offset + n) >= rp->r_size)));

                mutex_exit(&rp->r_statelock);

                if (!vpm_enable && pagecreate) {
                        /*
                         * The last argument tells segmap_pagecreate() to
                         * always lock the page, as opposed to sometimes
                         * returning with the page locked. This way we avoid a
                         * fault on the ensuing uiomove(), but also
                         * more importantly (to fix bug 1094402) we can
                         * call segmap_fault() to unlock the page in all
                         * cases. An alternative would be to modify
                         * segmap_pagecreate() to tell us when it is
                         * locking a page, but that's a fairly major
                         * interface change.
                         */
                        if (pgcreated == 0)
                                (void) segmap_pagecreate(segkmap, base,
                                    (uint_t)n, 1);
                        saved_base = base;
                        saved_n = n;
                }

                /*
                 * The number of bytes of data in the last page can not
                 * be accurately be determined while page is being
                 * uiomove'd to and the size of the file being updated.
                 * Thus, inform threads which need to know accurately
                 * how much data is in the last page of the file.  They
                 * will not do the i/o immediately, but will arrange for
                 * the i/o to happen later when this modify operation
                 * will have finished.
                 */
                ASSERT(!(rp->r_flags & R4MODINPROGRESS));
                mutex_enter(&rp->r_statelock);
                rp->r_flags |= R4MODINPROGRESS;
                rp->r_modaddr = (offset & MAXBMASK);
                mutex_exit(&rp->r_statelock);

                if (vpm_enable) {
                        /*
                         * Copy data. If new pages are created, part of
                         * the page that is not written will be initizliazed
                         * with zeros.
                         */
                        error = vpm_data_copy(vp, offset, n, uio,
                            !pagecreate, NULL, 0, S_WRITE);
                } else {
                        error = uiomove(base, n, UIO_WRITE, uio);
                }

                /*
                 * r_size is the maximum number of
                 * bytes known to be in the file.
                 * Make sure it is at least as high as the
                 * first unwritten byte pointed to by uio_loffset.
                 */
                mutex_enter(&rp->r_statelock);
                if (rp->r_size < uio->uio_loffset)
                        rp->r_size = uio->uio_loffset;
                rp->r_flags &= ~R4MODINPROGRESS;
                rp->r_flags |= R4DIRTY;
                mutex_exit(&rp->r_statelock);

                /* n = # of bytes written */
                n = (int)(uio->uio_loffset - offset);

                if (!vpm_enable) {
                        base += n;
                }

                tcount -= n;
                /*
                 * If we created pages w/o initializing them completely,
                 * we need to zero the part that wasn't set up.
                 * This happens on a most EOF write cases and if
                 * we had some sort of error during the uiomove.
                 */
                if (!vpm_enable && pagecreate) {
                        if ((uio->uio_loffset & PAGEOFFSET) || n == 0)
                                (void) kzero(base, PAGESIZE - n);

                        if (pgcreated) {
                                /*
                                 * Caller is responsible for this page,
                                 * it was not created in this loop.
                                 */
                                pgcreated = 0;
                        } else {
                                /*
                                 * For bug 1094402: segmap_pagecreate locks
                                 * page. Unlock it. This also unlocks the
                                 * pages allocated by page_create_va() in
                                 * segmap_pagecreate().
                                 */
                                sm_error = segmap_fault(kas.a_hat, segkmap,
                                    saved_base, saved_n,
                                    F_SOFTUNLOCK, S_WRITE);
                                if (error == 0)
                                        error = sm_error;
                        }
                }
        } while (tcount > 0 && error == 0);

        return (error);
}

int
nfs4_putpages(vnode_t *vp, uoff_t off, size_t len, int flags, cred_t *cr)
{
        rnode4_t *rp;
        page_t *pp;
        uoff_t eoff;
        uoff_t io_off;
        size_t io_len;
        int error;
        int rdirty;
        int err;

        rp = VTOR4(vp);
        ASSERT(rp->r_count > 0);

        if (!nfs4_has_pages(vp))
                return (0);

        ASSERT(vp->v_type != VCHR);

        /*
         * If R4OUTOFSPACE is set, then all writes turn into B_INVAL
         * writes.  B_FORCE is set to force the VM system to actually
         * invalidate the pages, even if the i/o failed.  The pages
         * need to get invalidated because they can't be written out
         * because there isn't any space left on either the server's
         * file system or in the user's disk quota.  The B_FREE bit
         * is cleared to avoid confusion as to whether this is a
         * request to place the page on the freelist or to destroy
         * it.
         */
        if ((rp->r_flags & R4OUTOFSPACE) ||
            (vp->v_vfsp->vfs_flag & VFS_UNMOUNTED))
                flags = (flags & ~B_FREE) | B_INVAL | B_FORCE;

        if (len == 0) {
                /*
                 * If doing a full file synchronous operation, then clear
                 * the R4DIRTY bit.  If a page gets dirtied while the flush
                 * is happening, then R4DIRTY will get set again.  The
                 * R4DIRTY bit must get cleared before the flush so that
                 * we don't lose this information.
                 *
                 * If there are no full file async write operations
                 * pending and RDIRTY bit is set, clear it.
                 */
                if (off == 0 &&
                    !(flags & B_ASYNC) &&
                    (rp->r_flags & R4DIRTY)) {
                        mutex_enter(&rp->r_statelock);
                        rdirty = (rp->r_flags & R4DIRTY);
                        rp->r_flags &= ~R4DIRTY;
                        mutex_exit(&rp->r_statelock);
                } else if (flags & B_ASYNC && off == 0) {
                        mutex_enter(&rp->r_statelock);
                        if (rp->r_flags & R4DIRTY && rp->r_awcount == 0) {
                                rdirty = (rp->r_flags & R4DIRTY);
                                rp->r_flags &= ~R4DIRTY;
                        }
                        mutex_exit(&rp->r_statelock);
                } else
                        rdirty = 0;

                /*
                 * Search the entire vp list for pages >= off, and flush
                 * the dirty pages.
                 */
                error = pvn_vplist_dirty(vp, off, rp->r_putapage,
                    flags, cr);

                /*
                 * If an error occurred and the file was marked as dirty
                 * before and we aren't forcibly invalidating pages, then
                 * reset the R4DIRTY flag.
                 */
                if (error && rdirty &&
                    (flags & (B_INVAL | B_FORCE)) != (B_INVAL | B_FORCE)) {
                        mutex_enter(&rp->r_statelock);
                        rp->r_flags |= R4DIRTY;
                        mutex_exit(&rp->r_statelock);
                }
        } else {
                /*
                 * Do a range from [off...off + len) looking for pages
                 * to deal with.
                 */
                error = 0;
                io_len = 0;
                eoff = off + len;
                mutex_enter(&rp->r_statelock);
                for (io_off = off; io_off < eoff && io_off < rp->r_size;
                    io_off += io_len) {
                        mutex_exit(&rp->r_statelock);
                        /*
                         * If we are not invalidating, synchronously
                         * freeing or writing pages use the routine
                         * page_lookup_nowait() to prevent reclaiming
                         * them from the free list.
                         */
                        if ((flags & B_INVAL) || !(flags & B_ASYNC)) {
                                pp = page_lookup(&vp->v_object, io_off,
                                                 (flags & (B_INVAL | B_FREE)) ? SE_EXCL : SE_SHARED);
                        } else {
                                pp = page_lookup_nowait(&vp->v_object,
                                                        io_off,
                                                        (flags & B_FREE) ? SE_EXCL : SE_SHARED);
                        }

                        if (pp == NULL || !pvn_getdirty(pp, flags))
                                io_len = PAGESIZE;
                        else {
                                err = (*rp->r_putapage)(vp, pp, &io_off,
                                    &io_len, flags, cr);
                                if (!error)
                                        error = err;
                                /*
                                 * "io_off" and "io_len" are returned as
                                 * the range of pages we actually wrote.
                                 * This allows us to skip ahead more quickly
                                 * since several pages may've been dealt
                                 * with by this iteration of the loop.
                                 */
                        }
                        mutex_enter(&rp->r_statelock);
                }
                mutex_exit(&rp->r_statelock);
        }

        return (error);
}

void
nfs4_invalidate_pages(vnode_t *vp, uoff_t off, cred_t *cr)
{
        rnode4_t *rp;

        rp = VTOR4(vp);
        if (IS_SHADOW(vp, rp))
                vp = RTOV4(rp);
        mutex_enter(&rp->r_statelock);
        while (rp->r_flags & R4TRUNCATE)
                cv_wait(&rp->r_cv, &rp->r_statelock);
        rp->r_flags |= R4TRUNCATE;
        if (off == 0) {
                rp->r_flags &= ~R4DIRTY;
                if (!(rp->r_flags & R4STALE))
                        rp->r_error = 0;
        }
        rp->r_truncaddr = off;
        mutex_exit(&rp->r_statelock);
        (void) pvn_vplist_dirty(vp, off, rp->r_putapage,
            B_INVAL | B_TRUNC, cr);
        mutex_enter(&rp->r_statelock);
        rp->r_flags &= ~R4TRUNCATE;
        cv_broadcast(&rp->r_cv);
        mutex_exit(&rp->r_statelock);
}

static int
nfs4_mnt_kstat_update(kstat_t *ksp, int rw)
{
        mntinfo4_t *mi;
        struct mntinfo_kstat *mik;
        vfs_t *vfsp;

        /* this is a read-only kstat. Bail out on a write */
        if (rw == KSTAT_WRITE)
                return (EACCES);


        /*
         * We don't want to wait here as kstat_chain_lock could be held by
         * dounmount(). dounmount() takes vfs_reflock before the chain lock
         * and thus could lead to a deadlock.
         */
        vfsp = (struct vfs *)ksp->ks_private;

        mi = VFTOMI4(vfsp);
        mik = (struct mntinfo_kstat *)ksp->ks_data;

        (void) strcpy(mik->mik_proto, mi->mi_curr_serv->sv_knconf->knc_proto);

        mik->mik_vers = (uint32_t)mi->mi_vers;
        mik->mik_flags = mi->mi_flags;
        /*
         * The sv_secdata holds the flavor the client specifies.
         * If the client uses default and a security negotiation
         * occurs, sv_currsec will point to the current flavor
         * selected from the server flavor list.
         * sv_currsec is NULL if no security negotiation takes place.
         */
        mik->mik_secmod = mi->mi_curr_serv->sv_currsec ?
            mi->mi_curr_serv->sv_currsec->secmod :
            mi->mi_curr_serv->sv_secdata->secmod;
        mik->mik_curread = (uint32_t)mi->mi_curread;
        mik->mik_curwrite = (uint32_t)mi->mi_curwrite;
        mik->mik_retrans = mi->mi_retrans;
        mik->mik_timeo = mi->mi_timeo;
        mik->mik_acregmin = HR2SEC(mi->mi_acregmin);
        mik->mik_acregmax = HR2SEC(mi->mi_acregmax);
        mik->mik_acdirmin = HR2SEC(mi->mi_acdirmin);
        mik->mik_acdirmax = HR2SEC(mi->mi_acdirmax);
        mik->mik_noresponse = (uint32_t)mi->mi_noresponse;
        mik->mik_failover = (uint32_t)mi->mi_failover;
        mik->mik_remap = (uint32_t)mi->mi_remap;

        (void) strcpy(mik->mik_curserver, mi->mi_curr_serv->sv_hostname);

        return (0);
}

void
nfs4_mnt_kstat_init(struct vfs *vfsp)
{
        mntinfo4_t *mi = VFTOMI4(vfsp);

        /*
         * PSARC 2001/697 Contract Private Interface
         * All nfs kstats are under SunMC contract
         * Please refer to the PSARC listed above and contact
         * SunMC before making any changes!
         *
         * Changes must be reviewed by Solaris File Sharing
         * Changes must be communicated to contract-2001-697@sun.com
         *
         */

        mi->mi_io_kstats = kstat_create_zone("nfs", getminor(vfsp->vfs_dev),
            NULL, "nfs", KSTAT_TYPE_IO, 1, 0, mi->mi_zone->zone_id);
        if (mi->mi_io_kstats) {
                if (mi->mi_zone->zone_id != GLOBAL_ZONEID)
                        kstat_zone_add(mi->mi_io_kstats, GLOBAL_ZONEID);
                mi->mi_io_kstats->ks_lock = &mi->mi_lock;
                kstat_install(mi->mi_io_kstats);
        }

        if ((mi->mi_ro_kstats = kstat_create_zone("nfs",
            getminor(vfsp->vfs_dev), "mntinfo", "misc", KSTAT_TYPE_RAW,
            sizeof (struct mntinfo_kstat), 0, mi->mi_zone->zone_id)) != NULL) {
                if (mi->mi_zone->zone_id != GLOBAL_ZONEID)
                        kstat_zone_add(mi->mi_ro_kstats, GLOBAL_ZONEID);
                mi->mi_ro_kstats->ks_update = nfs4_mnt_kstat_update;
                mi->mi_ro_kstats->ks_private = (void *)vfsp;
                kstat_install(mi->mi_ro_kstats);
        }

        nfs4_mnt_recov_kstat_init(vfsp);
}

void
nfs4_write_error(vnode_t *vp, int error, cred_t *cr)
{
        mntinfo4_t *mi;
        clock_t now = ddi_get_lbolt();

        mi = VTOMI4(vp);
        /*
         * In case of forced unmount, do not print any messages
         * since it can flood the console with error messages.
         */
        if (mi->mi_vfsp->vfs_flag & VFS_UNMOUNTED)
                return;

        /*
         * If the mount point is dead, not recoverable, do not
         * print error messages that can flood the console.
         */
        if (mi->mi_flags & MI4_RECOV_FAIL)
                return;

        /*
         * No use in flooding the console with ENOSPC
         * messages from the same file system.
         */
        if ((error != ENOSPC && error != EDQUOT) ||
            now - mi->mi_printftime > 0) {
                zoneid_t zoneid = mi->mi_zone->zone_id;

#ifdef DEBUG
                nfs_perror(error, "NFS%ld write error on host %s: %m.\n",
                    mi->mi_vers, VTOR4(vp)->r_server->sv_hostname, NULL);
#else
                nfs_perror(error, "NFS write error on host %s: %m.\n",
                    VTOR4(vp)->r_server->sv_hostname, NULL);
#endif
                if (error == ENOSPC || error == EDQUOT) {
                        zcmn_err(zoneid, CE_CONT,
                            "^File: userid=%d, groupid=%d\n",
                            crgetuid(cr), crgetgid(cr));
                        if (crgetuid(curthread->t_cred) != crgetuid(cr) ||
                            crgetgid(curthread->t_cred) != crgetgid(cr)) {
                                zcmn_err(zoneid, CE_CONT,
                                    "^User: userid=%d, groupid=%d\n",
                                    crgetuid(curthread->t_cred),
                                    crgetgid(curthread->t_cred));
                        }
                        mi->mi_printftime = now +
                            nfs_write_error_interval * hz;
                }
                sfh4_printfhandle(VTOR4(vp)->r_fh);
#ifdef DEBUG
                if (error == EACCES) {
                        zcmn_err(zoneid, CE_CONT,
                            "nfs_bio: cred is%s kcred\n",
                            cr == kcred ? "" : " not");
                }
#endif
        }
}

/*
 * Return non-zero if the given file can be safely memory mapped.  Locks
 * are safe if whole-file (length and offset are both zero).
 */

#define SAFE_LOCK(flk)  ((flk).l_start == 0 && (flk).l_len == 0)

static int
nfs4_safemap(const vnode_t *vp)
{
        locklist_t      *llp, *next_llp;
        int             safe = 1;
        rnode4_t        *rp = VTOR4(vp);

        ASSERT(nfs_rw_lock_held(&rp->r_lkserlock, RW_WRITER));

        NFS4_DEBUG(nfs4_client_map_debug, (CE_NOTE, "nfs4_safemap: "
            "vp = %p", (void *)vp));

        /*
         * Review all the locks for the vnode, both ones that have been
         * acquired and ones that are pending.  We assume that
         * flk_active_locks_for_vp() has merged any locks that can be
         * merged (so that if a process has the entire file locked, it is
         * represented as a single lock).
         *
         * Note that we can't bail out of the loop if we find a non-safe
         * lock, because we have to free all the elements in the llp list.
         * We might be able to speed up this code slightly by not looking
         * at each lock's l_start and l_len fields once we've found a
         * non-safe lock.
         */

        llp = flk_active_locks_for_vp(vp);
        while (llp) {
                NFS4_DEBUG(nfs4_client_map_debug, (CE_NOTE,
                    "nfs4_safemap: active lock (%" PRId64 ", %" PRId64 ")",
                    llp->ll_flock.l_start, llp->ll_flock.l_len));
                if (!SAFE_LOCK(llp->ll_flock)) {
                        safe = 0;
                        NFS4_DEBUG(nfs4_client_map_debug, (CE_NOTE,
                            "nfs4_safemap: unsafe active lock (%" PRId64
                            ", %" PRId64 ")", llp->ll_flock.l_start,
                            llp->ll_flock.l_len));
                }
                next_llp = llp->ll_next;
                VN_RELE(llp->ll_vp);
                kmem_free(llp, sizeof (*llp));
                llp = next_llp;
        }

        NFS4_DEBUG(nfs4_client_map_debug, (CE_NOTE, "nfs4_safemap: %s",
            safe ? "safe" : "unsafe"));
        return (safe);
}

/*
 * Return whether there is a lost LOCK or LOCKU queued up for the given
 * file that would make an mmap request unsafe.  cf. nfs4_safemap().
 */

bool_t
nfs4_map_lost_lock_conflict(vnode_t *vp)
{
        bool_t conflict = FALSE;
        nfs4_lost_rqst_t *lrp;
        mntinfo4_t *mi = VTOMI4(vp);

        mutex_enter(&mi->mi_lock);
        for (lrp = list_head(&mi->mi_lost_state); lrp != NULL;
            lrp = list_next(&mi->mi_lost_state, lrp)) {
                if (lrp->lr_op != OP_LOCK && lrp->lr_op != OP_LOCKU)
                        continue;
                ASSERT(lrp->lr_vp != NULL);
                if (!fop_cmp(lrp->lr_vp, vp, NULL))
                        continue;       /* different file */
                if (!SAFE_LOCK(*lrp->lr_flk)) {
                        conflict = TRUE;
                        break;
                }
        }

        mutex_exit(&mi->mi_lock);
        return (conflict);
}

/*
 * nfs_lockcompletion:
 *
 * If the vnode has a lock that makes it unsafe to cache the file, mark it
 * as non cachable (set VNOCACHE bit).
 */

void
nfs4_lockcompletion(vnode_t *vp, int cmd)
{
        rnode4_t *rp = VTOR4(vp);

        ASSERT(nfs_rw_lock_held(&rp->r_lkserlock, RW_WRITER));
        ASSERT(!IS_SHADOW(vp, rp));

        if (cmd == F_SETLK || cmd == F_SETLKW) {

                if (!nfs4_safemap(vp)) {
                        mutex_enter(&vp->v_lock);
                        vp->v_flag |= VNOCACHE;
                        mutex_exit(&vp->v_lock);
                } else {
                        mutex_enter(&vp->v_lock);
                        vp->v_flag &= ~VNOCACHE;
                        mutex_exit(&vp->v_lock);
                }
        }
        /*
         * The cached attributes of the file are stale after acquiring
         * the lock on the file. They were updated when the file was
         * opened, but not updated when the lock was acquired. Therefore the
         * cached attributes are invalidated after the lock is obtained.
         */
        PURGE_ATTRCACHE4(vp);
}

/* ARGSUSED */
static void *
nfs4_mi_init(zoneid_t zoneid)
{
        struct mi4_globals *mig;

        mig = kmem_alloc(sizeof (*mig), KM_SLEEP);
        mutex_init(&mig->mig_lock, NULL, MUTEX_DEFAULT, NULL);
        list_create(&mig->mig_list, sizeof (mntinfo4_t),
            offsetof(mntinfo4_t, mi_zone_node));
        mig->mig_destructor_called = B_FALSE;
        return (mig);
}

/*
 * Callback routine to tell all NFSv4 mounts in the zone to start tearing down
 * state and killing off threads.
 */
/* ARGSUSED */
static void
nfs4_mi_shutdown(zoneid_t zoneid, void *data)
{
        struct mi4_globals *mig = data;
        mntinfo4_t *mi;
        nfs4_server_t *np;

        NFS4_DEBUG(nfs4_client_zone_debug, (CE_NOTE,
            "nfs4_mi_shutdown zone %d\n", zoneid));
        ASSERT(mig != NULL);
        for (;;) {
                mutex_enter(&mig->mig_lock);
                mi = list_head(&mig->mig_list);
                if (mi == NULL) {
                        mutex_exit(&mig->mig_lock);
                        break;
                }

                NFS4_DEBUG(nfs4_client_zone_debug, (CE_NOTE,
                    "nfs4_mi_shutdown stopping vfs %p\n", (void *)mi->mi_vfsp));
                /*
                 * purge the DNLC for this filesystem
                 */
                (void) dnlc_purge_vfsp(mi->mi_vfsp, 0);
                /*
                 * Tell existing async worker threads to exit.
                 */
                mutex_enter(&mi->mi_async_lock);
                mi->mi_max_threads = 0;
                NFS4_WAKEALL_ASYNC_WORKERS(mi->mi_async_work_cv);
                /*
                 * Set the appropriate flags, signal and wait for both the
                 * async manager and the inactive thread to exit when they're
                 * done with their current work.
                 */
                mutex_enter(&mi->mi_lock);
                mi->mi_flags |= (MI4_ASYNC_MGR_STOP|MI4_DEAD);
                mutex_exit(&mi->mi_lock);
                mutex_exit(&mi->mi_async_lock);
                if (mi->mi_manager_thread) {
                        nfs4_async_manager_stop(mi->mi_vfsp);
                }
                if (mi->mi_inactive_thread) {
                        mutex_enter(&mi->mi_async_lock);
                        cv_signal(&mi->mi_inact_req_cv);
                        /*
                         * Wait for the inactive thread to exit.
                         */
                        while (mi->mi_inactive_thread != NULL) {
                                cv_wait(&mi->mi_async_cv, &mi->mi_async_lock);
                        }
                        mutex_exit(&mi->mi_async_lock);
                }
                /*
                 * Wait for the recovery thread to complete, that is, it will
                 * signal when it is done using the "mi" structure and about
                 * to exit
                 */
                mutex_enter(&mi->mi_lock);
                while (mi->mi_in_recovery > 0)
                        cv_wait(&mi->mi_cv_in_recov, &mi->mi_lock);
                mutex_exit(&mi->mi_lock);
                /*
                 * We're done when every mi has been done or the list is empty.
                 * This one is done, remove it from the list.
                 */
                list_remove(&mig->mig_list, mi);
                mutex_exit(&mig->mig_lock);
                zone_rele_ref(&mi->mi_zone_ref, ZONE_REF_NFSV4);

                /*
                 * Release hold on vfs and mi done to prevent race with zone
                 * shutdown. This releases the hold in nfs4_mi_zonelist_add.
                 */
                VFS_RELE(mi->mi_vfsp);
                MI4_RELE(mi);
        }
        /*
         * Tell each renew thread in the zone to exit
         */
        mutex_enter(&nfs4_server_lst_lock);
        for (np = nfs4_server_lst.forw; np != &nfs4_server_lst; np = np->forw) {
                mutex_enter(&np->s_lock);
                if (np->zoneid == zoneid) {
                        /*
                         * We add another hold onto the nfs4_server_t
                         * because this will make sure tha the nfs4_server_t
                         * stays around until nfs4_callback_fini_zone destroys
                         * the zone. This way, the renew thread can
                         * unconditionally release its holds on the
                         * nfs4_server_t.
                         */
                        np->s_refcnt++;
                        nfs4_mark_srv_dead(np);
                }
                mutex_exit(&np->s_lock);
        }
        mutex_exit(&nfs4_server_lst_lock);
}

static void
nfs4_mi_free_globals(struct mi4_globals *mig)
{
        list_destroy(&mig->mig_list);   /* makes sure the list is empty */
        mutex_destroy(&mig->mig_lock);
        kmem_free(mig, sizeof (*mig));
}

/* ARGSUSED */
static void
nfs4_mi_destroy(zoneid_t zoneid, void *data)
{
        struct mi4_globals *mig = data;

        NFS4_DEBUG(nfs4_client_zone_debug, (CE_NOTE,
            "nfs4_mi_destroy zone %d\n", zoneid));
        ASSERT(mig != NULL);
        mutex_enter(&mig->mig_lock);
        if (list_head(&mig->mig_list) != NULL) {
                /* Still waiting for VFS_FREEVFS() */
                mig->mig_destructor_called = B_TRUE;
                mutex_exit(&mig->mig_lock);
                return;
        }
        nfs4_mi_free_globals(mig);
}

/*
 * Add an NFS mount to the per-zone list of NFS mounts.
 */
void
nfs4_mi_zonelist_add(mntinfo4_t *mi)
{
        struct mi4_globals *mig;

        mig = zone_getspecific(mi4_list_key, mi->mi_zone);
        mutex_enter(&mig->mig_lock);
        list_insert_head(&mig->mig_list, mi);
        /*
         * hold added to eliminate race with zone shutdown -this will be
         * released in mi_shutdown
         */
        MI4_HOLD(mi);
        VFS_HOLD(mi->mi_vfsp);
        mutex_exit(&mig->mig_lock);
}

/*
 * Remove an NFS mount from the per-zone list of NFS mounts.
 */
int
nfs4_mi_zonelist_remove(mntinfo4_t *mi)
{
        struct mi4_globals *mig;
        int ret = 0;

        mig = zone_getspecific(mi4_list_key, mi->mi_zone);
        mutex_enter(&mig->mig_lock);
        mutex_enter(&mi->mi_lock);
        /* if this mi is marked dead, then the zone already released it */
        if (!(mi->mi_flags & MI4_DEAD)) {
                list_remove(&mig->mig_list, mi);
                mutex_exit(&mi->mi_lock);

                /* release the holds put on in zonelist_add(). */
                VFS_RELE(mi->mi_vfsp);
                MI4_RELE(mi);
                ret = 1;
        } else {
                mutex_exit(&mi->mi_lock);
        }

        /*
         * We can be called asynchronously by VFS_FREEVFS() after the zone
         * shutdown/destroy callbacks have executed; if so, clean up the zone's
         * mi globals.
         */
        if (list_head(&mig->mig_list) == NULL &&
            mig->mig_destructor_called == B_TRUE) {
                nfs4_mi_free_globals(mig);
                return (ret);
        }
        mutex_exit(&mig->mig_lock);
        return (ret);
}

void
nfs_free_mi4(mntinfo4_t *mi)
{
        nfs4_open_owner_t       *foop;
        nfs4_oo_hash_bucket_t   *bucketp;
        nfs4_debug_msg_t        *msgp;
        int i;
        servinfo4_t             *svp;

        /*
         * Code introduced here should be carefully evaluated to make
         * sure none of the freed resources are accessed either directly
         * or indirectly after freeing them. For eg: Introducing calls to
         * NFS4_DEBUG that use mntinfo4_t structure member after freeing
         * the structure members or other routines calling back into NFS
         * accessing freed mntinfo4_t structure member.
         */
        mutex_enter(&mi->mi_lock);
        ASSERT(mi->mi_recovthread == NULL);
        ASSERT(mi->mi_flags & MI4_ASYNC_MGR_STOP);
        mutex_exit(&mi->mi_lock);
        mutex_enter(&mi->mi_async_lock);
        ASSERT(mi->mi_threads[NFS4_ASYNC_QUEUE] == 0 &&
            mi->mi_threads[NFS4_ASYNC_PGOPS_QUEUE] == 0);
        ASSERT(mi->mi_manager_thread == NULL);
        mutex_exit(&mi->mi_async_lock);
        if (mi->mi_io_kstats) {
                kstat_delete(mi->mi_io_kstats);
                mi->mi_io_kstats = NULL;
        }
        if (mi->mi_ro_kstats) {
                kstat_delete(mi->mi_ro_kstats);
                mi->mi_ro_kstats = NULL;
        }
        if (mi->mi_recov_ksp) {
                kstat_delete(mi->mi_recov_ksp);
                mi->mi_recov_ksp = NULL;
        }
        mutex_enter(&mi->mi_msg_list_lock);
        while (msgp = list_head(&mi->mi_msg_list)) {
                list_remove(&mi->mi_msg_list, msgp);
                nfs4_free_msg(msgp);
        }
        mutex_exit(&mi->mi_msg_list_lock);
        list_destroy(&mi->mi_msg_list);
        if (mi->mi_fname != NULL)
                fn_rele(&mi->mi_fname);
        if (mi->mi_rootfh != NULL)
                sfh4_rele(&mi->mi_rootfh);
        if (mi->mi_srvparentfh != NULL)
                sfh4_rele(&mi->mi_srvparentfh);
        svp = mi->mi_servers;
        sv4_free(svp);
        mutex_destroy(&mi->mi_lock);
        mutex_destroy(&mi->mi_async_lock);
        mutex_destroy(&mi->mi_msg_list_lock);
        nfs_rw_destroy(&mi->mi_recovlock);
        nfs_rw_destroy(&mi->mi_rename_lock);
        nfs_rw_destroy(&mi->mi_fh_lock);
        cv_destroy(&mi->mi_failover_cv);
        cv_destroy(&mi->mi_async_reqs_cv);
        cv_destroy(&mi->mi_async_work_cv[NFS4_ASYNC_QUEUE]);
        cv_destroy(&mi->mi_async_work_cv[NFS4_ASYNC_PGOPS_QUEUE]);
        cv_destroy(&mi->mi_async_cv);
        cv_destroy(&mi->mi_inact_req_cv);
        /*
         * Destroy the oo hash lists and mutexes for the cred hash table.
         */
        for (i = 0; i < NFS4_NUM_OO_BUCKETS; i++) {
                bucketp = &(mi->mi_oo_list[i]);
                /* Destroy any remaining open owners on the list */
                foop = list_head(&bucketp->b_oo_hash_list);
                while (foop != NULL) {
                        list_remove(&bucketp->b_oo_hash_list, foop);
                        nfs4_destroy_open_owner(foop);
                        foop = list_head(&bucketp->b_oo_hash_list);
                }
                list_destroy(&bucketp->b_oo_hash_list);
                mutex_destroy(&bucketp->b_lock);
        }
        /*
         * Empty and destroy the freed open owner list.
         */
        foop = list_head(&mi->mi_foo_list);
        while (foop != NULL) {
                list_remove(&mi->mi_foo_list, foop);
                nfs4_destroy_open_owner(foop);
                foop = list_head(&mi->mi_foo_list);
        }
        list_destroy(&mi->mi_foo_list);
        list_destroy(&mi->mi_bseqid_list);
        list_destroy(&mi->mi_lost_state);
        avl_destroy(&mi->mi_filehandles);
        kmem_free(mi, sizeof (*mi));
}
void
mi_hold(mntinfo4_t *mi)
{
        atomic_inc_32(&mi->mi_count);
        ASSERT(mi->mi_count != 0);
}

void
mi_rele(mntinfo4_t *mi)
{
        ASSERT(mi->mi_count != 0);
        if (atomic_dec_32_nv(&mi->mi_count) == 0) {
                nfs_free_mi4(mi);
        }
}

vnode_t    nfs4_xattr_notsupp_vnode;

void
nfs4_clnt_init(void)
{
        nfs4_vnops_init();
        (void) nfs4_rnode_init();
        (void) nfs4_shadow_init();
        (void) nfs4_acache_init();
        (void) nfs4_subr_init();
        nfs4_acl_init();
        nfs_idmap_init();
        nfs4_callback_init();
        nfs4_secinfo_init();
#ifdef  DEBUG
        tsd_create(&nfs4_tsd_key, NULL);
#endif

        /*
         * Add a CPR callback so that we can update client
         * lease after a suspend and resume.
         */
        cid = callb_add(nfs4_client_cpr_callb, 0, CB_CL_CPR_RPC, "nfs4");

        zone_key_create(&mi4_list_key, nfs4_mi_init, nfs4_mi_shutdown,
            nfs4_mi_destroy);

        /*
         * Initialize the reference count of the notsupp xattr cache vnode to 1
         * so that it never goes away (fop_inactive isn't called on it).
         */
        vmobject_init(&nfs4_xattr_notsupp_vnode.v_object, &nfs4_xattr_notsupp_vnode);
        vn_reinit(&nfs4_xattr_notsupp_vnode);
}

void
nfs4_clnt_fini(void)
{
        (void) zone_key_delete(mi4_list_key);
        nfs4_vnops_fini();
        (void) nfs4_rnode_fini();
        (void) nfs4_shadow_fini();
        (void) nfs4_acache_fini();
        (void) nfs4_subr_fini();
        nfs_idmap_fini();
        nfs4_callback_fini();
        nfs4_secinfo_fini();
#ifdef  DEBUG
        tsd_destroy(&nfs4_tsd_key);
#endif
        if (cid)
                (void) callb_delete(cid);
}

/*ARGSUSED*/
static boolean_t
nfs4_client_cpr_callb(void *arg, int code)
{
        /*
         * We get called for Suspend and Resume events.
         * For the suspend case we simply don't care!
         */
        if (code == CB_CODE_CPR_CHKPT) {
                return (B_TRUE);
        }

        /*
         * When we get to here we are in the process of
         * resuming the system from a previous suspend.
         */
        nfs4_client_resumed = gethrestime_sec();
        return (B_TRUE);
}

void
nfs4_renew_lease_thread(nfs4_server_t *sp)
{
        int     error = 0;
        time_t  tmp_last_renewal_time, tmp_time, tmp_now_time, kip_secs;
        clock_t tick_delay = 0;
        clock_t time_left = 0;
        callb_cpr_t cpr_info;
        kmutex_t cpr_lock;

        NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
            "nfs4_renew_lease_thread: acting on sp 0x%p", (void*)sp));
        mutex_init(&cpr_lock, NULL, MUTEX_DEFAULT, NULL);
        CALLB_CPR_INIT(&cpr_info, &cpr_lock, callb_generic_cpr, "nfsv4Lease");

        mutex_enter(&sp->s_lock);
        /* sp->s_lease_time is set via a GETATTR */
        sp->last_renewal_time = gethrestime_sec();
        sp->lease_valid = NFS4_LEASE_UNINITIALIZED;
        ASSERT(sp->s_refcnt >= 1);

        for (;;) {
                if (!sp->state_ref_count ||
                    sp->lease_valid != NFS4_LEASE_VALID) {

                        kip_secs = MAX((sp->s_lease_time >> 1) -
                            (3 * sp->propagation_delay.tv_sec), 1);

                        tick_delay = SEC_TO_TICK(kip_secs);

                        NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
                            "nfs4_renew_lease_thread: no renew : thread "
                            "wait %ld secs", kip_secs));

                        NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
                            "nfs4_renew_lease_thread: no renew : "
                            "state_ref_count %d, lease_valid %d",
                            sp->state_ref_count, sp->lease_valid));

                        mutex_enter(&cpr_lock);
                        CALLB_CPR_SAFE_BEGIN(&cpr_info);
                        mutex_exit(&cpr_lock);
                        time_left = cv_reltimedwait(&sp->cv_thread_exit,
                            &sp->s_lock, tick_delay, TR_CLOCK_TICK);
                        mutex_enter(&cpr_lock);
                        CALLB_CPR_SAFE_END(&cpr_info, &cpr_lock);
                        mutex_exit(&cpr_lock);

                        NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
                            "nfs4_renew_lease_thread: no renew: "
                            "time left %ld", time_left));

                        if (sp->s_thread_exit == NFS4_THREAD_EXIT)
                                goto die;
                        continue;
                }

                tmp_last_renewal_time = sp->last_renewal_time;

                tmp_time = gethrestime_sec() - sp->last_renewal_time +
                    (3 * sp->propagation_delay.tv_sec);

                NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
                    "nfs4_renew_lease_thread: tmp_time %ld, "
                    "sp->last_renewal_time %ld", tmp_time,
                    sp->last_renewal_time));

                kip_secs = MAX((sp->s_lease_time >> 1) - tmp_time, 1);

                tick_delay = SEC_TO_TICK(kip_secs);

                NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
                    "nfs4_renew_lease_thread: valid lease: sleep for %ld "
                    "secs", kip_secs));

                mutex_enter(&cpr_lock);
                CALLB_CPR_SAFE_BEGIN(&cpr_info);
                mutex_exit(&cpr_lock);
                time_left = cv_reltimedwait(&sp->cv_thread_exit, &sp->s_lock,
                    tick_delay, TR_CLOCK_TICK);
                mutex_enter(&cpr_lock);
                CALLB_CPR_SAFE_END(&cpr_info, &cpr_lock);
                mutex_exit(&cpr_lock);

                NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
                    "nfs4_renew_lease_thread: valid lease: time left %ld :"
                    "sp last_renewal_time %ld, nfs4_client_resumed %ld, "
                    "tmp_last_renewal_time %ld", time_left,
                    sp->last_renewal_time, nfs4_client_resumed,
                    tmp_last_renewal_time));

                if (sp->s_thread_exit == NFS4_THREAD_EXIT)
                        goto die;

                if (tmp_last_renewal_time == sp->last_renewal_time ||
                    (nfs4_client_resumed != 0 &&
                    nfs4_client_resumed > sp->last_renewal_time)) {
                        /*
                         * Issue RENEW op since we haven't renewed the lease
                         * since we slept.
                         */
                        tmp_now_time = gethrestime_sec();
                        error = nfs4renew(sp);
                        /*
                         * Need to re-acquire sp's lock, nfs4renew()
                         * relinqueshes it.
                         */
                        mutex_enter(&sp->s_lock);

                        /*
                         * See if someone changed s_thread_exit while we gave
                         * up s_lock.
                         */
                        if (sp->s_thread_exit == NFS4_THREAD_EXIT)
                                goto die;

                        if (!error) {
                                /*
                                 * check to see if we implicitly renewed while
                                 * we waited for a reply for our RENEW call.
                                 */
                                if (tmp_last_renewal_time ==
                                    sp->last_renewal_time) {
                                        /* no implicit renew came */
                                        sp->last_renewal_time = tmp_now_time;
                                } else {
                                        NFS4_DEBUG(nfs4_client_lease_debug,
                                            (CE_NOTE, "renew_thread: did "
                                            "implicit renewal before reply "
                                            "from server for RENEW"));
                                }
                        } else {
                                /* figure out error */
                                NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
                                    "renew_thread: nfs4renew returned error"
                                    " %d", error));
                        }

                }
        }

die:
        NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
            "nfs4_renew_lease_thread: thread exiting"));

        while (sp->s_otw_call_count != 0) {
                NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
                    "nfs4_renew_lease_thread: waiting for outstanding "
                    "otw calls to finish for sp 0x%p, current "
                    "s_otw_call_count %d", (void *)sp,
                    sp->s_otw_call_count));
                mutex_enter(&cpr_lock);
                CALLB_CPR_SAFE_BEGIN(&cpr_info);
                mutex_exit(&cpr_lock);
                cv_wait(&sp->s_cv_otw_count, &sp->s_lock);
                mutex_enter(&cpr_lock);
                CALLB_CPR_SAFE_END(&cpr_info, &cpr_lock);
                mutex_exit(&cpr_lock);
        }
        mutex_exit(&sp->s_lock);

        nfs4_server_rele(sp);           /* free the thread's reference */
        nfs4_server_rele(sp);           /* free the list's reference */
        sp = NULL;

done:
        mutex_enter(&cpr_lock);
        CALLB_CPR_EXIT(&cpr_info);      /* drops cpr_lock */
        mutex_destroy(&cpr_lock);

        NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
            "nfs4_renew_lease_thread: renew thread exit officially"));

        zthread_exit();
        /* NOT REACHED */
}

/*
 * Send out a RENEW op to the server.
 * Assumes sp is locked down.
 */
static int
nfs4renew(nfs4_server_t *sp)
{
        COMPOUND4args_clnt args;
        COMPOUND4res_clnt res;
        nfs_argop4 argop[1];
        int doqueue = 1;
        int rpc_error;
        cred_t *cr;
        mntinfo4_t *mi;
        timespec_t prop_time, after_time;
        int needrecov = FALSE;
        nfs4_recov_state_t recov_state;
        nfs4_error_t e = { 0, NFS4_OK, RPC_SUCCESS };

        NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE, "nfs4renew"));

        recov_state.rs_flags = 0;
        recov_state.rs_num_retry_despite_err = 0;

recov_retry:
        mi = sp->mntinfo4_list;
        VFS_HOLD(mi->mi_vfsp);
        mutex_exit(&sp->s_lock);
        ASSERT(mi != NULL);

        e.error = nfs4_start_op(mi, NULL, NULL, &recov_state);
        if (e.error) {
                VFS_RELE(mi->mi_vfsp);
                return (e.error);
        }

        /* Check to see if we're dealing with a marked-dead sp */
        mutex_enter(&sp->s_lock);
        if (sp->s_thread_exit == NFS4_THREAD_EXIT) {
                mutex_exit(&sp->s_lock);
                nfs4_end_op(mi, NULL, NULL, &recov_state, needrecov);
                VFS_RELE(mi->mi_vfsp);
                return (0);
        }

        /* Make sure mi hasn't changed on us */
        if (mi != sp->mntinfo4_list) {
                /* Must drop sp's lock to avoid a recursive mutex enter */
                mutex_exit(&sp->s_lock);
                nfs4_end_op(mi, NULL, NULL, &recov_state, needrecov);
                VFS_RELE(mi->mi_vfsp);
                mutex_enter(&sp->s_lock);
                goto recov_retry;
        }
        mutex_exit(&sp->s_lock);

        args.ctag = TAG_RENEW;

        args.array_len = 1;
        args.array = argop;

        argop[0].argop = OP_RENEW;

        mutex_enter(&sp->s_lock);
        argop[0].nfs_argop4_u.oprenew.clientid = sp->clientid;
        cr = sp->s_cred;
        crhold(cr);
        mutex_exit(&sp->s_lock);

        ASSERT(cr != NULL);

        /* used to figure out RTT for sp */
        gethrestime(&prop_time);

        NFS4_DEBUG(nfs4_client_call_debug, (CE_NOTE,
            "nfs4renew: %s call, sp 0x%p", needrecov ? "recov" : "first",
            (void*)sp));
        NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE, "before: %ld s %ld ns ",
            prop_time.tv_sec, prop_time.tv_nsec));

        DTRACE_PROBE2(nfs4__renew__start, nfs4_server_t *, sp,
            mntinfo4_t *, mi);

        rfs4call(mi, &args, &res, cr, &doqueue, 0, &e);
        crfree(cr);

        DTRACE_PROBE2(nfs4__renew__end, nfs4_server_t *, sp,
            mntinfo4_t *, mi);

        gethrestime(&after_time);

        mutex_enter(&sp->s_lock);
        sp->propagation_delay.tv_sec =
            MAX(1, after_time.tv_sec - prop_time.tv_sec);
        mutex_exit(&sp->s_lock);

        NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE, "after : %ld s %ld ns ",
            after_time.tv_sec, after_time.tv_nsec));

        if (e.error == 0 && res.status == NFS4ERR_CB_PATH_DOWN) {
                xdr_free(xdr_COMPOUND4res_clnt, (caddr_t)&res);
                nfs4_delegreturn_all(sp);
                nfs4_end_op(mi, NULL, NULL, &recov_state, needrecov);
                VFS_RELE(mi->mi_vfsp);
                /*
                 * If the server returns CB_PATH_DOWN, it has renewed
                 * the lease and informed us that the callback path is
                 * down.  Since the lease is renewed, just return 0 and
                 * let the renew thread proceed as normal.
                 */
                return (0);
        }

        needrecov = nfs4_needs_recovery(&e, FALSE, mi->mi_vfsp);
        if (!needrecov && e.error) {
                nfs4_end_op(mi, NULL, NULL, &recov_state, needrecov);
                VFS_RELE(mi->mi_vfsp);
                return (e.error);
        }

        rpc_error = e.error;

        if (needrecov) {
                NFS4_DEBUG(nfs4_client_recov_debug, (CE_NOTE,
                    "nfs4renew: initiating recovery\n"));

                if (nfs4_start_recovery(&e, mi, NULL, NULL, NULL, NULL,
                    OP_RENEW, NULL, NULL, NULL) == FALSE) {
                        nfs4_end_op(mi, NULL, NULL, &recov_state, needrecov);
                        VFS_RELE(mi->mi_vfsp);
                        if (!e.error)
                                xdr_free(xdr_COMPOUND4res_clnt, (caddr_t)&res);
                        mutex_enter(&sp->s_lock);
                        goto recov_retry;
                }
                /* fall through for res.status case */
        }

        if (res.status) {
                if (res.status == NFS4ERR_LEASE_MOVED) {
                        /*EMPTY*/
                        /*
                         * XXX need to try every mntinfo4 in sp->mntinfo4_list
                         * to renew the lease on that server
                         */
                }
                e.error = geterrno4(res.status);
        }

        if (!rpc_error)
                xdr_free(xdr_COMPOUND4res_clnt, (caddr_t)&res);

        nfs4_end_op(mi, NULL, NULL, &recov_state, needrecov);

        VFS_RELE(mi->mi_vfsp);

        return (e.error);
}

void
nfs4_inc_state_ref_count(mntinfo4_t *mi)
{
        nfs4_server_t   *sp;

        /* this locks down sp if it is found */
        sp = find_nfs4_server(mi);

        if (sp != NULL) {
                nfs4_inc_state_ref_count_nolock(sp, mi);
                mutex_exit(&sp->s_lock);
                nfs4_server_rele(sp);
        }
}

/*
 * Bump the number of OPEN files (ie: those with state) so we know if this
 * nfs4_server has any state to maintain a lease for or not.
 *
 * Also, marks the nfs4_server's lease valid if it hasn't been done so already.
 */
void
nfs4_inc_state_ref_count_nolock(nfs4_server_t *sp, mntinfo4_t *mi)
{
        ASSERT(mutex_owned(&sp->s_lock));

        sp->state_ref_count++;
        NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
            "nfs4_inc_state_ref_count: state_ref_count now %d",
            sp->state_ref_count));

        if (sp->lease_valid == NFS4_LEASE_UNINITIALIZED)
                sp->lease_valid = NFS4_LEASE_VALID;

        /*
         * If this call caused the lease to be marked valid and/or
         * took the state_ref_count from 0 to 1, then start the time
         * on lease renewal.
         */
        if (sp->lease_valid == NFS4_LEASE_VALID && sp->state_ref_count == 1)
                sp->last_renewal_time = gethrestime_sec();

        /* update the number of open files for mi */
        mi->mi_open_files++;
}

void
nfs4_dec_state_ref_count(mntinfo4_t *mi)
{
        nfs4_server_t   *sp;

        /* this locks down sp if it is found */
        sp = find_nfs4_server_all(mi, 1);

        if (sp != NULL) {
                nfs4_dec_state_ref_count_nolock(sp, mi);
                mutex_exit(&sp->s_lock);
                nfs4_server_rele(sp);
        }
}

/*
 * Decrement the number of OPEN files (ie: those with state) so we know if
 * this nfs4_server has any state to maintain a lease for or not.
 */
void
nfs4_dec_state_ref_count_nolock(nfs4_server_t *sp, mntinfo4_t *mi)
{
        ASSERT(mutex_owned(&sp->s_lock));
        ASSERT(sp->state_ref_count != 0);
        sp->state_ref_count--;

        NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
            "nfs4_dec_state_ref_count: state ref count now %d",
            sp->state_ref_count));

        mi->mi_open_files--;
        NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
            "nfs4_dec_state_ref_count: mi open files %d, v4 flags 0x%x",
            mi->mi_open_files, mi->mi_flags));

        /* We don't have to hold the mi_lock to test mi_flags */
        if (mi->mi_open_files == 0 &&
            (mi->mi_flags & MI4_REMOVE_ON_LAST_CLOSE)) {
                NFS4_DEBUG(nfs4_client_lease_debug, (CE_NOTE,
                    "nfs4_dec_state_ref_count: remove mntinfo4 %p since "
                    "we have closed the last open file", (void*)mi));
                nfs4_remove_mi_from_server(mi, sp);
        }
}

bool_t
inlease(nfs4_server_t *sp)
{
        bool_t result;

        ASSERT(mutex_owned(&sp->s_lock));

        if (sp->lease_valid == NFS4_LEASE_VALID &&
            gethrestime_sec() < sp->last_renewal_time + sp->s_lease_time)
                result = TRUE;
        else
                result = FALSE;

        return (result);
}


/*
 * Return non-zero if the given nfs4_server_t is going through recovery.
 */

int
nfs4_server_in_recovery(nfs4_server_t *sp)
{
        return (nfs_rw_lock_held(&sp->s_recovlock, RW_WRITER));
}

/*
 * Compare two shared filehandle objects.  Returns -1, 0, or +1, if the
 * first is less than, equal to, or greater than the second.
 */

int
sfh4cmp(const void *p1, const void *p2)
{
        const nfs4_sharedfh_t *sfh1 = (const nfs4_sharedfh_t *)p1;
        const nfs4_sharedfh_t *sfh2 = (const nfs4_sharedfh_t *)p2;

        return (nfs4cmpfh(&sfh1->sfh_fh, &sfh2->sfh_fh));
}

/*
 * Create a table for shared filehandle objects.
 */

void
sfh4_createtab(avl_tree_t *tab)
{
        avl_create(tab, sfh4cmp, sizeof (nfs4_sharedfh_t),
            offsetof(nfs4_sharedfh_t, sfh_tree));
}

/*
 * Return a shared filehandle object for the given filehandle.  The caller
 * is responsible for eventually calling sfh4_rele().
 */

nfs4_sharedfh_t *
sfh4_put(const nfs_fh4 *fh, mntinfo4_t *mi, nfs4_sharedfh_t *key)
{
        nfs4_sharedfh_t *sfh, *nsfh;
        avl_index_t where;
        nfs4_sharedfh_t skey;

        if (!key) {
                skey.sfh_fh = *fh;
                key = &skey;
        }

        nsfh = kmem_alloc(sizeof (nfs4_sharedfh_t), KM_SLEEP);
        nsfh->sfh_fh.nfs_fh4_len = fh->nfs_fh4_len;
        /*
         * We allocate the largest possible filehandle size because it's
         * not that big, and it saves us from possibly having to resize the
         * buffer later.
         */
        nsfh->sfh_fh.nfs_fh4_val = kmem_alloc(NFS4_FHSIZE, KM_SLEEP);
        bcopy(fh->nfs_fh4_val, nsfh->sfh_fh.nfs_fh4_val, fh->nfs_fh4_len);
        mutex_init(&nsfh->sfh_lock, NULL, MUTEX_DEFAULT, NULL);
        nsfh->sfh_refcnt = 1;
        nsfh->sfh_flags = SFH4_IN_TREE;
        nsfh->sfh_mi = mi;
        NFS4_DEBUG(nfs4_sharedfh_debug, (CE_NOTE, "sfh4_get: new object (%p)",
            (void *)nsfh));

        (void) nfs_rw_enter_sig(&mi->mi_fh_lock, RW_WRITER, 0);
        sfh = avl_find(&mi->mi_filehandles, key, &where);
        if (sfh != NULL) {
                mutex_enter(&sfh->sfh_lock);
                sfh->sfh_refcnt++;
                mutex_exit(&sfh->sfh_lock);
                nfs_rw_exit(&mi->mi_fh_lock);
                /* free our speculative allocs */
                kmem_free(nsfh->sfh_fh.nfs_fh4_val, NFS4_FHSIZE);
                kmem_free(nsfh, sizeof (nfs4_sharedfh_t));
                return (sfh);
        }

        avl_insert(&mi->mi_filehandles, nsfh, where);
        nfs_rw_exit(&mi->mi_fh_lock);

        return (nsfh);
}

/*
 * Return a shared filehandle object for the given filehandle.  The caller
 * is responsible for eventually calling sfh4_rele().
 */

nfs4_sharedfh_t *
sfh4_get(const nfs_fh4 *fh, mntinfo4_t *mi)
{
        nfs4_sharedfh_t *sfh;
        nfs4_sharedfh_t key;

        ASSERT(fh->nfs_fh4_len <= NFS4_FHSIZE);

#ifdef DEBUG
        if (nfs4_sharedfh_debug) {
                nfs4_fhandle_t fhandle;

                fhandle.fh_len = fh->nfs_fh4_len;
                bcopy(fh->nfs_fh4_val, fhandle.fh_buf, fhandle.fh_len);
                zcmn_err(mi->mi_zone->zone_id, CE_NOTE, "sfh4_get:");
                nfs4_printfhandle(&fhandle);
        }
#endif

        /*
         * If there's already an object for the given filehandle, bump the
         * reference count and return it.  Otherwise, create a new object
         * and add it to the AVL tree.
         */

        key.sfh_fh = *fh;

        (void) nfs_rw_enter_sig(&mi->mi_fh_lock, RW_READER, 0);
        sfh = avl_find(&mi->mi_filehandles, &key, NULL);
        if (sfh != NULL) {
                mutex_enter(&sfh->sfh_lock);
                sfh->sfh_refcnt++;
                NFS4_DEBUG(nfs4_sharedfh_debug, (CE_NOTE,
                    "sfh4_get: found existing %p, new refcnt=%d",
                    (void *)sfh, sfh->sfh_refcnt));
                mutex_exit(&sfh->sfh_lock);
                nfs_rw_exit(&mi->mi_fh_lock);
                return (sfh);
        }
        nfs_rw_exit(&mi->mi_fh_lock);

        return (sfh4_put(fh, mi, &key));
}

/*
 * Get a reference to the given shared filehandle object.
 */

void
sfh4_hold(nfs4_sharedfh_t *sfh)
{
        ASSERT(sfh->sfh_refcnt > 0);

        mutex_enter(&sfh->sfh_lock);
        sfh->sfh_refcnt++;
        NFS4_DEBUG(nfs4_sharedfh_debug,
            (CE_NOTE, "sfh4_hold %p, new refcnt=%d",
            (void *)sfh, sfh->sfh_refcnt));
        mutex_exit(&sfh->sfh_lock);
}

/*
 * Release a reference to the given shared filehandle object and null out
 * the given pointer.
 */

void
sfh4_rele(nfs4_sharedfh_t **sfhpp)
{
        mntinfo4_t *mi;
        nfs4_sharedfh_t *sfh = *sfhpp;

        ASSERT(sfh->sfh_refcnt > 0);

        mutex_enter(&sfh->sfh_lock);
        if (sfh->sfh_refcnt > 1) {
                sfh->sfh_refcnt--;
                NFS4_DEBUG(nfs4_sharedfh_debug, (CE_NOTE,
                    "sfh4_rele %p, new refcnt=%d",
                    (void *)sfh, sfh->sfh_refcnt));
                mutex_exit(&sfh->sfh_lock);
                goto finish;
        }
        mutex_exit(&sfh->sfh_lock);

        /*
         * Possibly the last reference, so get the lock for the table in
         * case it's time to remove the object from the table.
         */
        mi = sfh->sfh_mi;
        (void) nfs_rw_enter_sig(&mi->mi_fh_lock, RW_WRITER, 0);
        mutex_enter(&sfh->sfh_lock);
        sfh->sfh_refcnt--;
        if (sfh->sfh_refcnt > 0) {
                NFS4_DEBUG(nfs4_sharedfh_debug, (CE_NOTE,
                    "sfh4_rele %p, new refcnt=%d",
                    (void *)sfh, sfh->sfh_refcnt));
                mutex_exit(&sfh->sfh_lock);
                nfs_rw_exit(&mi->mi_fh_lock);
                goto finish;
        }

        NFS4_DEBUG(nfs4_sharedfh_debug, (CE_NOTE,
            "sfh4_rele %p, last ref", (void *)sfh));
        if (sfh->sfh_flags & SFH4_IN_TREE) {
                avl_remove(&mi->mi_filehandles, sfh);
                sfh->sfh_flags &= ~SFH4_IN_TREE;
        }
        mutex_exit(&sfh->sfh_lock);
        nfs_rw_exit(&mi->mi_fh_lock);
        mutex_destroy(&sfh->sfh_lock);
        kmem_free(sfh->sfh_fh.nfs_fh4_val, NFS4_FHSIZE);
        kmem_free(sfh, sizeof (nfs4_sharedfh_t));

finish:
        *sfhpp = NULL;
}

/*
 * Update the filehandle for the given shared filehandle object.
 */

int nfs4_warn_dupfh = 0;        /* if set, always warn about dup fhs below */

void
sfh4_update(nfs4_sharedfh_t *sfh, const nfs_fh4 *newfh)
{
        mntinfo4_t *mi = sfh->sfh_mi;
        nfs4_sharedfh_t *dupsfh;
        avl_index_t where;
        nfs4_sharedfh_t key;

#ifdef DEBUG
        mutex_enter(&sfh->sfh_lock);
        ASSERT(sfh->sfh_refcnt > 0);
        mutex_exit(&sfh->sfh_lock);
#endif
        ASSERT(newfh->nfs_fh4_len <= NFS4_FHSIZE);

        /*
         * The basic plan is to remove the shared filehandle object from
         * the table, update it to have the new filehandle, then reinsert
         * it.
         */

        (void) nfs_rw_enter_sig(&mi->mi_fh_lock, RW_WRITER, 0);
        mutex_enter(&sfh->sfh_lock);
        if (sfh->sfh_flags & SFH4_IN_TREE) {
                avl_remove(&mi->mi_filehandles, sfh);
                sfh->sfh_flags &= ~SFH4_IN_TREE;
        }
        mutex_exit(&sfh->sfh_lock);
        sfh->sfh_fh.nfs_fh4_len = newfh->nfs_fh4_len;
        bcopy(newfh->nfs_fh4_val, sfh->sfh_fh.nfs_fh4_val,
            sfh->sfh_fh.nfs_fh4_len);

        /*
         * XXX If there is already a shared filehandle object with the new
         * filehandle, we're in trouble, because the rnode code assumes
         * that there is only one shared filehandle object for a given
         * filehandle.  So issue a warning (for read-write mounts only)
         * and don't try to re-insert the given object into the table.
         * Hopefully the given object will quickly go away and everyone
         * will use the new object.
         */
        key.sfh_fh = *newfh;
        dupsfh = avl_find(&mi->mi_filehandles, &key, &where);
        if (dupsfh != NULL) {
                if (!(mi->mi_vfsp->vfs_flag & VFS_RDONLY) || nfs4_warn_dupfh) {
                        zcmn_err(mi->mi_zone->zone_id, CE_WARN, "sfh4_update: "
                            "duplicate filehandle detected");
                        sfh4_printfhandle(dupsfh);
                }
        } else {
                avl_insert(&mi->mi_filehandles, sfh, where);
                mutex_enter(&sfh->sfh_lock);
                sfh->sfh_flags |= SFH4_IN_TREE;
                mutex_exit(&sfh->sfh_lock);
        }
        nfs_rw_exit(&mi->mi_fh_lock);
}

/*
 * Copy out the current filehandle for the given shared filehandle object.
 */

void
sfh4_copyval(const nfs4_sharedfh_t *sfh, nfs4_fhandle_t *fhp)
{
        mntinfo4_t *mi = sfh->sfh_mi;

        ASSERT(sfh->sfh_refcnt > 0);

        (void) nfs_rw_enter_sig(&mi->mi_fh_lock, RW_READER, 0);
        fhp->fh_len = sfh->sfh_fh.nfs_fh4_len;
        ASSERT(fhp->fh_len <= NFS4_FHSIZE);
        bcopy(sfh->sfh_fh.nfs_fh4_val, fhp->fh_buf, fhp->fh_len);
        nfs_rw_exit(&mi->mi_fh_lock);
}

/*
 * Print out the filehandle for the given shared filehandle object.
 */

void
sfh4_printfhandle(const nfs4_sharedfh_t *sfh)
{
        nfs4_fhandle_t fhandle;

        sfh4_copyval(sfh, &fhandle);
        nfs4_printfhandle(&fhandle);
}

/*
 * Compare 2 fnames.  Returns -1 if the first is "less" than the second, 0
 * if they're the same, +1 if the first is "greater" than the second.  The
 * caller (or whoever's calling the AVL package) is responsible for
 * handling locking issues.
 */

static int
fncmp(const void *p1, const void *p2)
{
        const nfs4_fname_t *f1 = p1;
        const nfs4_fname_t *f2 = p2;
        int res;

        res = strcmp(f1->fn_name, f2->fn_name);
        /*
         * The AVL package wants +/-1, not arbitrary positive or negative
         * integers.
         */
        if (res > 0)
                res = 1;
        else if (res < 0)
                res = -1;
        return (res);
}

/*
 * Get or create an fname with the given name, as a child of the given
 * fname.  The caller is responsible for eventually releasing the reference
 * (fn_rele()).  parent may be NULL.
 */

nfs4_fname_t *
fn_get(nfs4_fname_t *parent, char *name, nfs4_sharedfh_t *sfh)
{
        nfs4_fname_t key;
        nfs4_fname_t *fnp;
        avl_index_t where;

        key.fn_name = name;

        /*
         * If there's already an fname registered with the given name, bump
         * its reference count and return it.  Otherwise, create a new one
         * and add it to the parent's AVL tree.
         *
         * fname entries we are looking for should match both name
         * and sfh stored in the fname.
         */
again:
        if (parent != NULL) {
                mutex_enter(&parent->fn_lock);
                fnp = avl_find(&parent->fn_children, &key, &where);
                if (fnp != NULL) {
                        /*
                         * This hold on fnp is released below later,
                         * in case this is not the fnp we want.
                         */
                        fn_hold(fnp);

                        if (fnp->fn_sfh == sfh) {
                                /*
                                 * We have found our entry.
                                 * put an hold and return it.
                                 */
                                mutex_exit(&parent->fn_lock);
                                return (fnp);
                        }

                        /*
                         * We have found an entry that has a mismatching
                         * fn_sfh. This could be a stale entry due to
                         * server side rename. We will remove this entry
                         * and make sure no such entries exist.
                         */
                        mutex_exit(&parent->fn_lock);
                        mutex_enter(&fnp->fn_lock);
                        if (fnp->fn_parent == parent) {
                                /*
                                 * Remove ourselves from parent's
                                 * fn_children tree.
                                 */
                                mutex_enter(&parent->fn_lock);
                                avl_remove(&parent->fn_children, fnp);
                                mutex_exit(&parent->fn_lock);
                                fn_rele(&fnp->fn_parent);
                        }
                        mutex_exit(&fnp->fn_lock);
                        fn_rele(&fnp);
                        goto again;
                }
        }

        fnp = kmem_alloc(sizeof (nfs4_fname_t), KM_SLEEP);
        mutex_init(&fnp->fn_lock, NULL, MUTEX_DEFAULT, NULL);
        fnp->fn_parent = parent;
        if (parent != NULL)
                fn_hold(parent);
        fnp->fn_len = strlen(name);
        ASSERT(fnp->fn_len < MAXNAMELEN);
        fnp->fn_name = kmem_alloc(fnp->fn_len + 1, KM_SLEEP);
        (void) strcpy(fnp->fn_name, name);
        fnp->fn_refcnt = 1;

        /*
         * This hold on sfh is later released
         * when we do the final fn_rele() on this fname.
         */
        sfh4_hold(sfh);
        fnp->fn_sfh = sfh;

        avl_create(&fnp->fn_children, fncmp, sizeof (nfs4_fname_t),
            offsetof(nfs4_fname_t, fn_tree));
        NFS4_DEBUG(nfs4_fname_debug, (CE_NOTE,
            "fn_get %p:%s, a new nfs4_fname_t!",
            (void *)fnp, fnp->fn_name));
        if (parent != NULL) {
                avl_insert(&parent->fn_children, fnp, where);
                mutex_exit(&parent->fn_lock);
        }

        return (fnp);
}

void
fn_hold(nfs4_fname_t *fnp)
{
        atomic_inc_32(&fnp->fn_refcnt);
        NFS4_DEBUG(nfs4_fname_debug, (CE_NOTE,
            "fn_hold %p:%s, new refcnt=%d",
            (void *)fnp, fnp->fn_name, fnp->fn_refcnt));
}

/*
 * Decrement the reference count of the given fname, and destroy it if its
 * reference count goes to zero.  Nulls out the given pointer.
 */

void
fn_rele(nfs4_fname_t **fnpp)
{
        nfs4_fname_t *parent;
        uint32_t newref;
        nfs4_fname_t *fnp;

recur:
        fnp = *fnpp;
        *fnpp = NULL;

        mutex_enter(&fnp->fn_lock);
        parent = fnp->fn_parent;
        if (parent != NULL)
                mutex_enter(&parent->fn_lock);  /* prevent new references */
        newref = atomic_dec_32_nv(&fnp->fn_refcnt);
        if (newref > 0) {
                NFS4_DEBUG(nfs4_fname_debug, (CE_NOTE,
                    "fn_rele %p:%s, new refcnt=%d",
                    (void *)fnp, fnp->fn_name, fnp->fn_refcnt));
                if (parent != NULL)
                        mutex_exit(&parent->fn_lock);
                mutex_exit(&fnp->fn_lock);
                return;
        }

        NFS4_DEBUG(nfs4_fname_debug, (CE_NOTE,
            "fn_rele %p:%s, last reference, deleting...",
            (void *)fnp, fnp->fn_name));
        if (parent != NULL) {
                avl_remove(&parent->fn_children, fnp);
                mutex_exit(&parent->fn_lock);
        }
        kmem_free(fnp->fn_name, fnp->fn_len + 1);
        sfh4_rele(&fnp->fn_sfh);
        mutex_destroy(&fnp->fn_lock);
        avl_destroy(&fnp->fn_children);
        kmem_free(fnp, sizeof (nfs4_fname_t));
        /*
         * Recursivly fn_rele the parent.
         * Use goto instead of a recursive call to avoid stack overflow.
         */
        if (parent != NULL) {
                fnpp = &parent;
                goto recur;
        }
}

/*
 * Returns the single component name of the given fname, in a MAXNAMELEN
 * string buffer, which the caller is responsible for freeing.  Note that
 * the name may become invalid as a result of fn_move().
 */

char *
fn_name(nfs4_fname_t *fnp)
{
        char *name;

        ASSERT(fnp->fn_len < MAXNAMELEN);
        name = kmem_alloc(MAXNAMELEN, KM_SLEEP);
        mutex_enter(&fnp->fn_lock);
        (void) strcpy(name, fnp->fn_name);
        mutex_exit(&fnp->fn_lock);

        return (name);
}


/*
 * fn_path_realloc
 *
 * This function, used only by fn_path, constructs
 * a new string which looks like "prepend" + "/" + "current".
 * by allocating a new string and freeing the old one.
 */
static void
fn_path_realloc(char **curses, char *prepend)
{
        int len, curlen = 0;
        char *news;

        if (*curses == NULL) {
                /*
                 * Prime the pump, allocate just the
                 * space for prepend and return that.
                 */
                len = strlen(prepend) + 1;
                news = kmem_alloc(len, KM_SLEEP);
                (void) strncpy(news, prepend, len);
        } else {
                /*
                 * Allocate the space  for a new string
                 * +1 +1 is for the "/" and the NULL
                 * byte at the end of it all.
                 */
                curlen = strlen(*curses);
                len = curlen + strlen(prepend) + 1 + 1;
                news = kmem_alloc(len, KM_SLEEP);
                (void) strncpy(news, prepend, len);
                (void) strcat(news, "/");
                (void) strcat(news, *curses);
                kmem_free(*curses, curlen + 1);
        }
        *curses = news;
}

/*
 * Returns the path name (starting from the fs root) for the given fname.
 * The caller is responsible for freeing.  Note that the path may be or
 * become invalid as a result of fn_move().
 */

char *
fn_path(nfs4_fname_t *fnp)
{
        char *path;
        nfs4_fname_t *nextfnp;

        if (fnp == NULL)
                return (NULL);

        path = NULL;

        /* walk up the tree constructing the pathname.  */

        fn_hold(fnp);                   /* adjust for later rele */
        do {
                mutex_enter(&fnp->fn_lock);
                /*
                 * Add fn_name in front of the current path
                 */
                fn_path_realloc(&path, fnp->fn_name);
                nextfnp = fnp->fn_parent;
                if (nextfnp != NULL)
                        fn_hold(nextfnp);
                mutex_exit(&fnp->fn_lock);
                fn_rele(&fnp);
                fnp = nextfnp;
        } while (fnp != NULL);

        return (path);
}

/*
 * Return a reference to the parent of the given fname, which the caller is
 * responsible for eventually releasing.
 */

nfs4_fname_t *
fn_parent(nfs4_fname_t *fnp)
{
        nfs4_fname_t *parent;

        mutex_enter(&fnp->fn_lock);
        parent = fnp->fn_parent;
        if (parent != NULL)
                fn_hold(parent);
        mutex_exit(&fnp->fn_lock);

        return (parent);
}

/*
 * Update fnp so that its parent is newparent and its name is newname.
 */

void
fn_move(nfs4_fname_t *fnp, nfs4_fname_t *newparent, char *newname)
{
        nfs4_fname_t *parent, *tmpfnp;
        ssize_t newlen;
        nfs4_fname_t key;
        avl_index_t where;

        /*
         * This assert exists to catch the client trying to rename
         * a dir to be a child of itself.  This happened at a recent
         * bakeoff against a 3rd party (broken) server which allowed
         * the rename to succeed.  If it trips it means that:
         *      a) the code in nfs4rename that detects this case is broken
         *      b) the server is broken (since it allowed the bogus rename)
         *
         * For non-DEBUG kernels, prepare for a recursive mutex_enter
         * panic below from:  mutex_enter(&newparent->fn_lock);
         */
        ASSERT(fnp != newparent);

        /*
         * Remove fnp from its current parent, change its name, then add it
         * to newparent. It might happen that fnp was replaced by another
         * nfs4_fname_t with the same fn_name in parent->fn_children.
         * In such case, fnp->fn_parent is NULL and we skip the removal
         * of fnp from its current parent.
         */
        mutex_enter(&fnp->fn_lock);
        parent = fnp->fn_parent;
        if (parent != NULL) {
                mutex_enter(&parent->fn_lock);
                avl_remove(&parent->fn_children, fnp);
                mutex_exit(&parent->fn_lock);
                fn_rele(&fnp->fn_parent);
        }

        newlen = strlen(newname);
        if (newlen != fnp->fn_len) {
                ASSERT(newlen < MAXNAMELEN);
                kmem_free(fnp->fn_name, fnp->fn_len + 1);
                fnp->fn_name = kmem_alloc(newlen + 1, KM_SLEEP);
                fnp->fn_len = newlen;
        }
        (void) strcpy(fnp->fn_name, newname);

again:
        mutex_enter(&newparent->fn_lock);
        key.fn_name = fnp->fn_name;
        tmpfnp = avl_find(&newparent->fn_children, &key, &where);
        if (tmpfnp != NULL) {
                /*
                 * This could be due to a file that was unlinked while
                 * open, or perhaps the rnode is in the free list.  Remove
                 * it from newparent and let it go away on its own.  The
                 * contorted code is to deal with lock order issues and
                 * race conditions.
                 */
                fn_hold(tmpfnp);
                mutex_exit(&newparent->fn_lock);
                mutex_enter(&tmpfnp->fn_lock);
                if (tmpfnp->fn_parent == newparent) {
                        mutex_enter(&newparent->fn_lock);
                        avl_remove(&newparent->fn_children, tmpfnp);
                        mutex_exit(&newparent->fn_lock);
                        fn_rele(&tmpfnp->fn_parent);
                }
                mutex_exit(&tmpfnp->fn_lock);
                fn_rele(&tmpfnp);
                goto again;
        }
        fnp->fn_parent = newparent;
        fn_hold(newparent);
        avl_insert(&newparent->fn_children, fnp, where);
        mutex_exit(&newparent->fn_lock);
        mutex_exit(&fnp->fn_lock);
}

#ifdef DEBUG
/*
 * Return non-zero if the type information makes sense for the given vnode.
 * Otherwise panic.
 */
int
nfs4_consistent_type(vnode_t *vp)
{
        rnode4_t *rp = VTOR4(vp);

        if (nfs4_vtype_debug && vp->v_type != VNON &&
            rp->r_attr.va_type != VNON && vp->v_type != rp->r_attr.va_type) {
                cmn_err(CE_PANIC, "vnode %p type mismatch; v_type=%d, "
                    "rnode attr type=%d", (void *)vp, vp->v_type,
                    rp->r_attr.va_type);
        }

        return (1);
}
#endif /* DEBUG */