MFC r212652: zfs: catch up with vm_page_sleep_if_busy changes

[FreeBSD/stable/8.git] / sys / cddl / contrib / opensolaris / uts / common / fs / zfs / zfs_vnops.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) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 */

/* Portions Copyright 2007 Jeremy Teo */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/systm.h>
#include <sys/sysmacros.h>
#include <sys/resource.h>
#include <sys/vfs.h>
#include <sys/vnode.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/kmem.h>
#include <sys/taskq.h>
#include <sys/uio.h>
#include <sys/atomic.h>
#include <sys/namei.h>
#include <sys/mman.h>
#include <sys/cmn_err.h>
#include <sys/errno.h>
#include <sys/unistd.h>
#include <sys/zfs_dir.h>
#include <sys/zfs_ioctl.h>
#include <sys/fs/zfs.h>
#include <sys/dmu.h>
#include <sys/spa.h>
#include <sys/txg.h>
#include <sys/dbuf.h>
#include <sys/zap.h>
#include <sys/dirent.h>
#include <sys/policy.h>
#include <sys/sunddi.h>
#include <sys/filio.h>
#include <sys/sid.h>
#include <sys/zfs_ctldir.h>
#include <sys/zfs_fuid.h>
#include <sys/dnlc.h>
#include <sys/zfs_rlock.h>
#include <sys/extdirent.h>
#include <sys/kidmap.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/sf_buf.h>
#include <sys/sched.h>
#include <sys/acl.h>

/*
 * Programming rules.
 *
 * Each vnode op performs some logical unit of work.  To do this, the ZPL must
 * properly lock its in-core state, create a DMU transaction, do the work,
 * record this work in the intent log (ZIL), commit the DMU transaction,
 * and wait for the intent log to commit if it is a synchronous operation.
 * Moreover, the vnode ops must work in both normal and log replay context.
 * The ordering of events is important to avoid deadlocks and references
 * to freed memory.  The example below illustrates the following Big Rules:
 *
 *  (1) A check must be made in each zfs thread for a mounted file system.
 *      This is done avoiding races using ZFS_ENTER(zfsvfs).
 *      A ZFS_EXIT(zfsvfs) is needed before all returns.  Any znodes
 *      must be checked with ZFS_VERIFY_ZP(zp).  Both of these macros
 *      can return EIO from the calling function.
 *
 *  (2) VN_RELE() should always be the last thing except for zil_commit()
 *      (if necessary) and ZFS_EXIT(). This is for 3 reasons:
 *      First, if it's the last reference, the vnode/znode
 *      can be freed, so the zp may point to freed memory.  Second, the last
 *      reference will call zfs_zinactive(), which may induce a lot of work --
 *      pushing cached pages (which acquires range locks) and syncing out
 *      cached atime changes.  Third, zfs_zinactive() may require a new tx,
 *      which could deadlock the system if you were already holding one.
 *      If you must call VN_RELE() within a tx then use VN_RELE_ASYNC().
 *
 *  (3) All range locks must be grabbed before calling dmu_tx_assign(),
 *      as they can span dmu_tx_assign() calls.
 *
 *  (4) Always pass TXG_NOWAIT as the second argument to dmu_tx_assign().
 *      This is critical because we don't want to block while holding locks.
 *      Note, in particular, that if a lock is sometimes acquired before
 *      the tx assigns, and sometimes after (e.g. z_lock), then failing to
 *      use a non-blocking assign can deadlock the system.  The scenario:
 *
 *      Thread A has grabbed a lock before calling dmu_tx_assign().
 *      Thread B is in an already-assigned tx, and blocks for this lock.
 *      Thread A calls dmu_tx_assign(TXG_WAIT) and blocks in txg_wait_open()
 *      forever, because the previous txg can't quiesce until B's tx commits.
 *
 *      If dmu_tx_assign() returns ERESTART and zfsvfs->z_assign is TXG_NOWAIT,
 *      then drop all locks, call dmu_tx_wait(), and try again.
 *
 *  (5) If the operation succeeded, generate the intent log entry for it
 *      before dropping locks.  This ensures that the ordering of events
 *      in the intent log matches the order in which they actually occurred.
 *      During ZIL replay the zfs_log_* functions will update the sequence
 *      number to indicate the zil transaction has replayed.
 *
 *  (6) At the end of each vnode op, the DMU tx must always commit,
 *      regardless of whether there were any errors.
 *
 *  (7) After dropping all locks, invoke zil_commit(zilog, seq, foid)
 *      to ensure that synchronous semantics are provided when necessary.
 *
 * In general, this is how things should be ordered in each vnode op:
 *
 *      ZFS_ENTER(zfsvfs);              // exit if unmounted
 * top:
 *      zfs_dirent_lock(&dl, ...)       // lock directory entry (may VN_HOLD())
 *      rw_enter(...);                  // grab any other locks you need
 *      tx = dmu_tx_create(...);        // get DMU tx
 *      dmu_tx_hold_*();                // hold each object you might modify
 *      error = dmu_tx_assign(tx, TXG_NOWAIT);  // try to assign
 *      if (error) {
 *              rw_exit(...);           // drop locks
 *              zfs_dirent_unlock(dl);  // unlock directory entry
 *              VN_RELE(...);           // release held vnodes
 *              if (error == ERESTART) {
 *                      dmu_tx_wait(tx);
 *                      dmu_tx_abort(tx);
 *                      goto top;
 *              }
 *              dmu_tx_abort(tx);       // abort DMU tx
 *              ZFS_EXIT(zfsvfs);       // finished in zfs
 *              return (error);         // really out of space
 *      }
 *      error = do_real_work();         // do whatever this VOP does
 *      if (error == 0)
 *              zfs_log_*(...);         // on success, make ZIL entry
 *      dmu_tx_commit(tx);              // commit DMU tx -- error or not
 *      rw_exit(...);                   // drop locks
 *      zfs_dirent_unlock(dl);          // unlock directory entry
 *      VN_RELE(...);                   // release held vnodes
 *      zil_commit(zilog, seq, foid);   // synchronous when necessary
 *      ZFS_EXIT(zfsvfs);               // finished in zfs
 *      return (error);                 // done, report error
 */

/* ARGSUSED */
static int
zfs_open(vnode_t **vpp, int flag, cred_t *cr, caller_context_t *ct)
{
        znode_t *zp = VTOZ(*vpp);
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        if ((flag & FWRITE) && (zp->z_phys->zp_flags & ZFS_APPENDONLY) &&
            ((flag & FAPPEND) == 0)) {
                ZFS_EXIT(zfsvfs);
                return (EPERM);
        }

        if (!zfs_has_ctldir(zp) && zp->z_zfsvfs->z_vscan &&
            ZTOV(zp)->v_type == VREG &&
            !(zp->z_phys->zp_flags & ZFS_AV_QUARANTINED) &&
            zp->z_phys->zp_size > 0) {
                if (fs_vscan(*vpp, cr, 0) != 0) {
                        ZFS_EXIT(zfsvfs);
                        return (EACCES);
                }
        }

        /* Keep a count of the synchronous opens in the znode */
        if (flag & (FSYNC | FDSYNC))
                atomic_inc_32(&zp->z_sync_cnt);

        ZFS_EXIT(zfsvfs);
        return (0);
}

/* ARGSUSED */
static int
zfs_close(vnode_t *vp, int flag, int count, offset_t offset, cred_t *cr,
    caller_context_t *ct)
{
        znode_t *zp = VTOZ(vp);
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        /* Decrement the synchronous opens in the znode */
        if ((flag & (FSYNC | FDSYNC)) && (count == 1))
                atomic_dec_32(&zp->z_sync_cnt);

        /*
         * Clean up any locks held by this process on the vp.
         */
        cleanlocks(vp, ddi_get_pid(), 0);
        cleanshares(vp, ddi_get_pid());

        if (!zfs_has_ctldir(zp) && zp->z_zfsvfs->z_vscan &&
            ZTOV(zp)->v_type == VREG &&
            !(zp->z_phys->zp_flags & ZFS_AV_QUARANTINED) &&
            zp->z_phys->zp_size > 0)
                VERIFY(fs_vscan(vp, cr, 1) == 0);

        ZFS_EXIT(zfsvfs);
        return (0);
}

/*
 * Lseek support for finding holes (cmd == _FIO_SEEK_HOLE) and
 * data (cmd == _FIO_SEEK_DATA). "off" is an in/out parameter.
 */
static int
zfs_holey(vnode_t *vp, u_long cmd, offset_t *off)
{
        znode_t *zp = VTOZ(vp);
        uint64_t noff = (uint64_t)*off; /* new offset */
        uint64_t file_sz;
        int error;
        boolean_t hole;

        file_sz = zp->z_phys->zp_size;
        if (noff >= file_sz)  {
                return (ENXIO);
        }

        if (cmd == _FIO_SEEK_HOLE)
                hole = B_TRUE;
        else
                hole = B_FALSE;

        error = dmu_offset_next(zp->z_zfsvfs->z_os, zp->z_id, hole, &noff);

        /* end of file? */
        if ((error == ESRCH) || (noff > file_sz)) {
                /*
                 * Handle the virtual hole at the end of file.
                 */
                if (hole) {
                        *off = file_sz;
                        return (0);
                }
                return (ENXIO);
        }

        if (noff < *off)
                return (error);
        *off = noff;
        return (error);
}

/* ARGSUSED */
static int
zfs_ioctl(vnode_t *vp, u_long com, intptr_t data, int flag, cred_t *cred,
    int *rvalp, caller_context_t *ct)
{
        offset_t off;
        int error;
        zfsvfs_t *zfsvfs;
        znode_t *zp;

        switch (com) {
        case _FIOFFS:
                return (0);

                /*
                 * The following two ioctls are used by bfu.  Faking out,
                 * necessary to avoid bfu errors.
                 */
        case _FIOGDIO:
        case _FIOSDIO:
                return (0);

        case _FIO_SEEK_DATA:
        case _FIO_SEEK_HOLE:
                if (ddi_copyin((void *)data, &off, sizeof (off), flag))
                        return (EFAULT);

                zp = VTOZ(vp);
                zfsvfs = zp->z_zfsvfs;
                ZFS_ENTER(zfsvfs);
                ZFS_VERIFY_ZP(zp);

                /* offset parameter is in/out */
                error = zfs_holey(vp, com, &off);
                ZFS_EXIT(zfsvfs);
                if (error)
                        return (error);
                if (ddi_copyout(&off, (void *)data, sizeof (off), flag))
                        return (EFAULT);
                return (0);
        }
        return (ENOTTY);
}

static vm_page_t
page_lookup(vnode_t *vp, int64_t start, int64_t off, int64_t nbytes)
{
        vm_object_t obj;
        vm_page_t pp;

        obj = vp->v_object;
        VM_OBJECT_LOCK_ASSERT(obj, MA_OWNED);

        for (;;) {
                if ((pp = vm_page_lookup(obj, OFF_TO_IDX(start))) != NULL &&
                    vm_page_is_valid(pp, (vm_offset_t)off, nbytes)) {
                        if ((pp->oflags & VPO_BUSY) != 0) {
                                /*
                                 * Reference the page before unlocking and
                                 * sleeping so that the page daemon is less
                                 * likely to reclaim it.
                                 */
                                vm_page_lock_queues();
                                vm_page_flag_set(pp, PG_REFERENCED);
                                vm_page_sleep(pp, "zfsmwb");
                                continue;
                        }
                        vm_page_busy(pp);
                        vm_page_lock_queues();
                        vm_page_undirty(pp);
                        vm_page_unlock_queues();
                } else {
                        if (__predict_false(obj->cache != NULL)) {
                                vm_page_cache_free(obj, OFF_TO_IDX(start),
                                    OFF_TO_IDX(start) + 1);
                        }
                        pp = NULL;
                }
                break;
        }
        return (pp);
}

static void
page_unlock(vm_page_t pp)
{

        vm_page_wakeup(pp);
}

static caddr_t
zfs_map_page(vm_page_t pp, struct sf_buf **sfp)
{

        sched_pin();
        *sfp = sf_buf_alloc(pp, SFB_CPUPRIVATE);
        return ((caddr_t)sf_buf_kva(*sfp));
}

static void
zfs_unmap_page(struct sf_buf *sf)
{

        sf_buf_free(sf);
        sched_unpin();
}


/*
 * When a file is memory mapped, we must keep the IO data synchronized
 * between the DMU cache and the memory mapped pages.  What this means:
 *
 * On Write:    If we find a memory mapped page, we write to *both*
 *              the page and the dmu buffer.
 */

static void
update_pages(vnode_t *vp, int64_t start, int len, objset_t *os, uint64_t oid,
    int segflg, dmu_tx_t *tx)
{
        vm_object_t obj;
        struct sf_buf *sf;
        int64_t off;

        ASSERT(vp->v_mount != NULL);
        obj = vp->v_object;
        ASSERT(obj != NULL);

        off = start & PAGEOFFSET;
        VM_OBJECT_LOCK(obj);
        for (start &= PAGEMASK; len > 0; start += PAGESIZE) {
                vm_page_t pp;
                uint64_t nbytes = MIN(PAGESIZE - off, len);

                if ((pp = page_lookup(vp, start, off, nbytes)) != NULL) {
                        caddr_t va;

                        VM_OBJECT_UNLOCK(obj);
                        va = zfs_map_page(pp, &sf);
                        if (segflg == UIO_NOCOPY) {
                                (void) dmu_write(os, oid, start+off, nbytes,
                                    va+off, tx);
                        } else {
                                (void) dmu_read(os, oid, start+off, nbytes,
                                    va+off, DMU_READ_PREFETCH);;
                        }
                        zfs_unmap_page(sf);
                        VM_OBJECT_LOCK(obj);
                        page_unlock(pp);

                }
                len -= nbytes;
                off = 0;
        }
        VM_OBJECT_UNLOCK(obj);
}

/*
 * When a file is memory mapped, we must keep the IO data synchronized
 * between the DMU cache and the memory mapped pages.  What this means:
 *
 * On Read:     We "read" preferentially from memory mapped pages,
 *              else we default from the dmu buffer.
 *
 * NOTE: We will always "break up" the IO into PAGESIZE uiomoves when
 *      the file is memory mapped.
 */
static int
mappedread(vnode_t *vp, int nbytes, uio_t *uio)
{
        znode_t *zp = VTOZ(vp);
        objset_t *os = zp->z_zfsvfs->z_os;
        vm_object_t obj;
        vm_page_t m;
        struct sf_buf *sf;
        int64_t start, off;
        caddr_t va;
        int len = nbytes;
        int error = 0;
        uint64_t dirbytes;

        ASSERT(vp->v_mount != NULL);
        obj = vp->v_object;
        ASSERT(obj != NULL);

        start = uio->uio_loffset;
        off = start & PAGEOFFSET;
        dirbytes = 0;
        VM_OBJECT_LOCK(obj);
        for (start &= PAGEMASK; len > 0; start += PAGESIZE) {
                uint64_t bytes = MIN(PAGESIZE - off, len);

again:
                if ((m = vm_page_lookup(obj, OFF_TO_IDX(start))) != NULL &&
                    vm_page_is_valid(m, (vm_offset_t)off, bytes)) {
                        if ((m->oflags & VPO_BUSY) != 0) {
                                /*
                                 * Reference the page before unlocking and
                                 * sleeping so that the page daemon is less
                                 * likely to reclaim it.
                                 */
                                vm_page_lock_queues();
                                vm_page_flag_set(m, PG_REFERENCED);
                                vm_page_sleep(m, "zfsmrb");
                                goto again;
                        }

                        vm_page_busy(m);
                        VM_OBJECT_UNLOCK(obj);
                        if (dirbytes > 0) {
                                error = dmu_read_uio(os, zp->z_id, uio,
                                    dirbytes);
                                dirbytes = 0;
                        }
                        if (error == 0) {
                                sched_pin();
                                sf = sf_buf_alloc(m, SFB_CPUPRIVATE);
                                va = (caddr_t)sf_buf_kva(sf);
                                error = uiomove(va + off, bytes, UIO_READ, uio);
                                sf_buf_free(sf);
                                sched_unpin();
                        }
                        VM_OBJECT_LOCK(obj);
                        vm_page_wakeup(m);
                } else if (m != NULL && uio->uio_segflg == UIO_NOCOPY) {
                        /*
                         * The code below is here to make sendfile(2) work
                         * correctly with ZFS. As pointed out by ups@
                         * sendfile(2) should be changed to use VOP_GETPAGES(),
                         * but it pessimize performance of sendfile/UFS, that's
                         * why I handle this special case in ZFS code.
                         */
                        if ((m->oflags & VPO_BUSY) != 0) {
                                /*
                                 * Reference the page before unlocking and
                                 * sleeping so that the page daemon is less
                                 * likely to reclaim it.
                                 */
                                vm_page_lock_queues();
                                vm_page_flag_set(m, PG_REFERENCED);
                                vm_page_sleep(m, "zfsmrb");
                                goto again;
                        }
                        vm_page_busy(m);
                        VM_OBJECT_UNLOCK(obj);
                        if (dirbytes > 0) {
                                error = dmu_read_uio(os, zp->z_id, uio,
                                    dirbytes);
                                dirbytes = 0;
                        }
                        if (error == 0) {
                                sched_pin();
                                sf = sf_buf_alloc(m, SFB_CPUPRIVATE);
                                va = (caddr_t)sf_buf_kva(sf);
                                error = dmu_read(os, zp->z_id, start + off,
                                    bytes, (void *)(va + off),
                                    DMU_READ_PREFETCH);
                                sf_buf_free(sf);
                                sched_unpin();
                        }
                        VM_OBJECT_LOCK(obj);
                        if (error == 0)
                                vm_page_set_valid(m, off, bytes);
                        vm_page_wakeup(m);
                        if (error == 0) {
                                uio->uio_resid -= bytes;
                                uio->uio_offset += bytes;
                        }
                } else {
                        dirbytes += bytes;
                }
                len -= bytes;
                off = 0;
                if (error)
                        break;
        }
        VM_OBJECT_UNLOCK(obj);
        if (error == 0 && dirbytes > 0)
                error = dmu_read_uio(os, zp->z_id, uio, dirbytes);
        return (error);
}

offset_t zfs_read_chunk_size = 1024 * 1024; /* Tunable */

/*
 * Read bytes from specified file into supplied buffer.
 *
 *      IN:     vp      - vnode of file to be read from.
 *              uio     - structure supplying read location, range info,
 *                        and return buffer.
 *              ioflag  - SYNC flags; used to provide FRSYNC semantics.
 *              cr      - credentials of caller.
 *              ct      - caller context
 *
 *      OUT:    uio     - updated offset and range, buffer filled.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Side Effects:
 *      vp - atime updated if byte count > 0
 */
/* ARGSUSED */
static int
zfs_read(vnode_t *vp, uio_t *uio, int ioflag, cred_t *cr, caller_context_t *ct)
{
        znode_t         *zp = VTOZ(vp);
        zfsvfs_t        *zfsvfs = zp->z_zfsvfs;
        objset_t        *os;
        ssize_t         n, nbytes;
        int             error;
        rl_t            *rl;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);
        os = zfsvfs->z_os;

        if (zp->z_phys->zp_flags & ZFS_AV_QUARANTINED) {
                ZFS_EXIT(zfsvfs);
                return (EACCES);
        }

        /*
         * Validate file offset
         */
        if (uio->uio_loffset < (offset_t)0) {
                ZFS_EXIT(zfsvfs);
                return (EINVAL);
        }

        /*
         * Fasttrack empty reads
         */
        if (uio->uio_resid == 0) {
                ZFS_EXIT(zfsvfs);
                return (0);
        }

        /*
         * Check for mandatory locks
         */
        if (MANDMODE((mode_t)zp->z_phys->zp_mode)) {
                if (error = chklock(vp, FREAD,
                    uio->uio_loffset, uio->uio_resid, uio->uio_fmode, ct)) {
                        ZFS_EXIT(zfsvfs);
                        return (error);
                }
        }

        /*
         * If we're in FRSYNC mode, sync out this znode before reading it.
         */
        if (ioflag & FRSYNC)
                zil_commit(zfsvfs->z_log, zp->z_last_itx, zp->z_id);

        /*
         * Lock the range against changes.
         */
        rl = zfs_range_lock(zp, uio->uio_loffset, uio->uio_resid, RL_READER);

        /*
         * If we are reading past end-of-file we can skip
         * to the end; but we might still need to set atime.
         */
        if (uio->uio_loffset >= zp->z_phys->zp_size) {
                error = 0;
                goto out;
        }

        ASSERT(uio->uio_loffset < zp->z_phys->zp_size);
        n = MIN(uio->uio_resid, zp->z_phys->zp_size - uio->uio_loffset);

        while (n > 0) {
                nbytes = MIN(n, zfs_read_chunk_size -
                    P2PHASE(uio->uio_loffset, zfs_read_chunk_size));

                if (vn_has_cached_data(vp))
                        error = mappedread(vp, nbytes, uio);
                else
                        error = dmu_read_uio(os, zp->z_id, uio, nbytes);
                if (error) {
                        /* convert checksum errors into IO errors */
                        if (error == ECKSUM)
                                error = EIO;
                        break;
                }

                n -= nbytes;
        }

out:
        zfs_range_unlock(rl);

        ZFS_ACCESSTIME_STAMP(zfsvfs, zp);
        ZFS_EXIT(zfsvfs);
        return (error);
}

/*
 * Fault in the pages of the first n bytes specified by the uio structure.
 * 1 byte in each page is touched and the uio struct is unmodified.
 * Any error will exit this routine as this is only a best
 * attempt to get the pages resident. This is a copy of ufs_trans_touch().
 */
static void
zfs_prefault_write(ssize_t n, struct uio *uio)
{
        struct iovec *iov;
        ulong_t cnt, incr;
        caddr_t p;

        if (uio->uio_segflg != UIO_USERSPACE)
                return;

        iov = uio->uio_iov;

        while (n) {
                cnt = MIN(iov->iov_len, n);
                if (cnt == 0) {
                        /* empty iov entry */
                        iov++;
                        continue;
                }
                n -= cnt;
                /*
                 * touch each page in this segment.
                 */
                p = iov->iov_base;
                while (cnt) {
                        if (fubyte(p) == -1)
                                return;
                        incr = MIN(cnt, PAGESIZE);
                        p += incr;
                        cnt -= incr;
                }
                /*
                 * touch the last byte in case it straddles a page.
                 */
                p--;
                if (fubyte(p) == -1)
                        return;
                iov++;
        }
}

/*
 * Write the bytes to a file.
 *
 *      IN:     vp      - vnode of file to be written to.
 *              uio     - structure supplying write location, range info,
 *                        and data buffer.
 *              ioflag  - IO_APPEND flag set if in append mode.
 *              cr      - credentials of caller.
 *              ct      - caller context (NFS/CIFS fem monitor only)
 *
 *      OUT:    uio     - updated offset and range.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      vp - ctime|mtime updated if byte count > 0
 */
/* ARGSUSED */
static int
zfs_write(vnode_t *vp, uio_t *uio, int ioflag, cred_t *cr, caller_context_t *ct)
{
        znode_t         *zp = VTOZ(vp);
        rlim64_t        limit = MAXOFFSET_T;
        ssize_t         start_resid = uio->uio_resid;
        ssize_t         tx_bytes;
        uint64_t        end_size;
        dmu_tx_t        *tx;
        zfsvfs_t        *zfsvfs = zp->z_zfsvfs;
        zilog_t         *zilog;
        offset_t        woff;
        ssize_t         n, nbytes;
        rl_t            *rl;
        int             max_blksz = zfsvfs->z_max_blksz;
        uint64_t        pflags;
        int             error;
        arc_buf_t       *abuf;

        /*
         * Fasttrack empty write
         */
        n = start_resid;
        if (n == 0)
                return (0);

        if (limit == RLIM64_INFINITY || limit > MAXOFFSET_T)
                limit = MAXOFFSET_T;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        /*
         * If immutable or not appending then return EPERM
         */
        pflags = zp->z_phys->zp_flags;
        if ((pflags & (ZFS_IMMUTABLE | ZFS_READONLY)) ||
            ((pflags & ZFS_APPENDONLY) && !(ioflag & FAPPEND) &&
            (uio->uio_loffset < zp->z_phys->zp_size))) {
                ZFS_EXIT(zfsvfs);
                return (EPERM);
        }

        zilog = zfsvfs->z_log;

        /*
         * Pre-fault the pages to ensure slow (eg NFS) pages
         * don't hold up txg.
         */
        zfs_prefault_write(n, uio);

        /*
         * If in append mode, set the io offset pointer to eof.
         */
        if (ioflag & IO_APPEND) {
                /*
                 * Range lock for a file append:
                 * The value for the start of range will be determined by
                 * zfs_range_lock() (to guarantee append semantics).
                 * If this write will cause the block size to increase,
                 * zfs_range_lock() will lock the entire file, so we must
                 * later reduce the range after we grow the block size.
                 */
                rl = zfs_range_lock(zp, 0, n, RL_APPEND);
                if (rl->r_len == UINT64_MAX) {
                        /* overlocked, zp_size can't change */
                        woff = uio->uio_loffset = zp->z_phys->zp_size;
                } else {
                        woff = uio->uio_loffset = rl->r_off;
                }
        } else {
                woff = uio->uio_loffset;
                /*
                 * Validate file offset
                 */
                if (woff < 0) {
                        ZFS_EXIT(zfsvfs);
                        return (EINVAL);
                }

                /*
                 * If we need to grow the block size then zfs_range_lock()
                 * will lock a wider range than we request here.
                 * Later after growing the block size we reduce the range.
                 */
                rl = zfs_range_lock(zp, woff, n, RL_WRITER);
        }

        if (woff >= limit) {
                zfs_range_unlock(rl);
                ZFS_EXIT(zfsvfs);
                return (EFBIG);
        }

        if ((woff + n) > limit || woff > (limit - n))
                n = limit - woff;

        /*
         * Check for mandatory locks
         */
        if (MANDMODE((mode_t)zp->z_phys->zp_mode) &&
            (error = chklock(vp, FWRITE, woff, n, uio->uio_fmode, ct)) != 0) {
                zfs_range_unlock(rl);
                ZFS_EXIT(zfsvfs);
                return (error);
        }
        end_size = MAX(zp->z_phys->zp_size, woff + n);

        /*
         * Write the file in reasonable size chunks.  Each chunk is written
         * in a separate transaction; this keeps the intent log records small
         * and allows us to do more fine-grained space accounting.
         */
        while (n > 0) {
                abuf = NULL;
                woff = uio->uio_loffset;

again:
                if (zfs_usergroup_overquota(zfsvfs,
                    B_FALSE, zp->z_phys->zp_uid) ||
                    zfs_usergroup_overquota(zfsvfs,
                    B_TRUE, zp->z_phys->zp_gid)) {
                        if (abuf != NULL)
                                dmu_return_arcbuf(abuf);
                        error = EDQUOT;
                        break;
                }

                /*
                 * If dmu_assign_arcbuf() is expected to execute with minimum
                 * overhead loan an arc buffer and copy user data to it before
                 * we enter a txg.  This avoids holding a txg forever while we
                 * pagefault on a hanging NFS server mapping.
                 */
                if (abuf == NULL && n >= max_blksz &&
                    woff >= zp->z_phys->zp_size &&
                    P2PHASE(woff, max_blksz) == 0 &&
                    zp->z_blksz == max_blksz) {
                        size_t cbytes;

                        abuf = dmu_request_arcbuf(zp->z_dbuf, max_blksz);
                        ASSERT(abuf != NULL);
                        ASSERT(arc_buf_size(abuf) == max_blksz);
                        if (error = uiocopy(abuf->b_data, max_blksz,
                            UIO_WRITE, uio, &cbytes)) {
                                dmu_return_arcbuf(abuf);
                                break;
                        }
                        ASSERT(cbytes == max_blksz);
                }

                /*
                 * Start a transaction.
                 */
                tx = dmu_tx_create(zfsvfs->z_os);
                dmu_tx_hold_bonus(tx, zp->z_id);
                dmu_tx_hold_write(tx, zp->z_id, woff, MIN(n, max_blksz));
                error = dmu_tx_assign(tx, TXG_NOWAIT);
                if (error) {
                        if (error == ERESTART) {
                                dmu_tx_wait(tx);
                                dmu_tx_abort(tx);
                                goto again;
                        }
                        dmu_tx_abort(tx);
                        if (abuf != NULL)
                                dmu_return_arcbuf(abuf);
                        break;
                }

                /*
                 * If zfs_range_lock() over-locked we grow the blocksize
                 * and then reduce the lock range.  This will only happen
                 * on the first iteration since zfs_range_reduce() will
                 * shrink down r_len to the appropriate size.
                 */
                if (rl->r_len == UINT64_MAX) {
                        uint64_t new_blksz;

                        if (zp->z_blksz > max_blksz) {
                                ASSERT(!ISP2(zp->z_blksz));
                                new_blksz = MIN(end_size, SPA_MAXBLOCKSIZE);
                        } else {
                                new_blksz = MIN(end_size, max_blksz);
                        }
                        zfs_grow_blocksize(zp, new_blksz, tx);
                        zfs_range_reduce(rl, woff, n);
                }

                /*
                 * XXX - should we really limit each write to z_max_blksz?
                 * Perhaps we should use SPA_MAXBLOCKSIZE chunks?
                 */
                nbytes = MIN(n, max_blksz - P2PHASE(woff, max_blksz));

                if (woff + nbytes > zp->z_phys->zp_size)
                        vnode_pager_setsize(vp, woff + nbytes);

                if (abuf == NULL) {
                        tx_bytes = uio->uio_resid;
                        error = dmu_write_uio(zfsvfs->z_os, zp->z_id, uio,
                            nbytes, tx);
                        tx_bytes -= uio->uio_resid;
                } else {
                        tx_bytes = nbytes;
                        ASSERT(tx_bytes == max_blksz);
                        dmu_assign_arcbuf(zp->z_dbuf, woff, abuf, tx);
                        ASSERT(tx_bytes <= uio->uio_resid);
                        uioskip(uio, tx_bytes);
                }

                /*
                 * XXXPJD: There are some cases (triggered by fsx) where
                 *         vn_has_cached_data(vp) returns false when it should
                 *         return true. This should be investigated.
                 */
#if 0
                if (tx_bytes && vn_has_cached_data(vp))
#else
                if (tx_bytes && vp->v_object != NULL)
#endif
                {
                        update_pages(vp, woff, tx_bytes, zfsvfs->z_os,
                            zp->z_id, uio->uio_segflg, tx);
                }

                /*
                 * If we made no progress, we're done.  If we made even
                 * partial progress, update the znode and ZIL accordingly.
                 */
                if (tx_bytes == 0) {
                        dmu_tx_commit(tx);
                        ASSERT(error != 0);
                        break;
                }

                /*
                 * Clear Set-UID/Set-GID bits on successful write if not
                 * privileged and at least one of the excute bits is set.
                 *
                 * It would be nice to to this after all writes have
                 * been done, but that would still expose the ISUID/ISGID
                 * to another app after the partial write is committed.
                 *
                 * Note: we don't call zfs_fuid_map_id() here because
                 * user 0 is not an ephemeral uid.
                 */
                mutex_enter(&zp->z_acl_lock);
                if ((zp->z_phys->zp_mode & (S_IXUSR | (S_IXUSR >> 3) |
                    (S_IXUSR >> 6))) != 0 &&
                    (zp->z_phys->zp_mode & (S_ISUID | S_ISGID)) != 0 &&
                    secpolicy_vnode_setid_retain(vp, cr,
                    (zp->z_phys->zp_mode & S_ISUID) != 0 &&
                    zp->z_phys->zp_uid == 0) != 0) {
                        zp->z_phys->zp_mode &= ~(S_ISUID | S_ISGID);
                }
                mutex_exit(&zp->z_acl_lock);

                /*
                 * Update time stamp.  NOTE: This marks the bonus buffer as
                 * dirty, so we don't have to do it again for zp_size.
                 */
                zfs_time_stamper(zp, CONTENT_MODIFIED, tx);

                /*
                 * Update the file size (zp_size) if it has changed;
                 * account for possible concurrent updates.
                 */
                while ((end_size = zp->z_phys->zp_size) < uio->uio_loffset)
                        (void) atomic_cas_64(&zp->z_phys->zp_size, end_size,
                            uio->uio_loffset);
                zfs_log_write(zilog, tx, TX_WRITE, zp, woff, tx_bytes, ioflag);
                dmu_tx_commit(tx);

                if (error != 0)
                        break;
                ASSERT(tx_bytes == nbytes);
                n -= nbytes;
        }

        zfs_range_unlock(rl);

        /*
         * If we're in replay mode, or we made no progress, return error.
         * Otherwise, it's at least a partial write, so it's successful.
         */
        if (zfsvfs->z_replay || uio->uio_resid == start_resid) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        if (ioflag & (FSYNC | FDSYNC))
                zil_commit(zilog, zp->z_last_itx, zp->z_id);

        ZFS_EXIT(zfsvfs);
        return (0);
}

void
zfs_get_done(dmu_buf_t *db, void *vzgd)
{
        zgd_t *zgd = (zgd_t *)vzgd;
        rl_t *rl = zgd->zgd_rl;
        vnode_t *vp = ZTOV(rl->r_zp);
        objset_t *os = rl->r_zp->z_zfsvfs->z_os;
        int vfslocked;

        vfslocked = VFS_LOCK_GIANT(vp->v_vfsp);
        dmu_buf_rele(db, vzgd);
        zfs_range_unlock(rl);
        /*
         * Release the vnode asynchronously as we currently have the
         * txg stopped from syncing.
         */
        VN_RELE_ASYNC(vp, dsl_pool_vnrele_taskq(dmu_objset_pool(os)));
        zil_add_block(zgd->zgd_zilog, zgd->zgd_bp);
        kmem_free(zgd, sizeof (zgd_t));
        VFS_UNLOCK_GIANT(vfslocked);
}

/*
 * Get data to generate a TX_WRITE intent log record.
 */
int
zfs_get_data(void *arg, lr_write_t *lr, char *buf, zio_t *zio)
{
        zfsvfs_t *zfsvfs = arg;
        objset_t *os = zfsvfs->z_os;
        znode_t *zp;
        uint64_t off = lr->lr_offset;
        dmu_buf_t *db;
        rl_t *rl;
        zgd_t *zgd;
        int dlen = lr->lr_length;               /* length of user data */
        int error = 0;

        ASSERT(zio);
        ASSERT(dlen != 0);

        /*
         * Nothing to do if the file has been removed
         */
        if (zfs_zget(zfsvfs, lr->lr_foid, &zp) != 0)
                return (ENOENT);
        if (zp->z_unlinked) {
                /*
                 * Release the vnode asynchronously as we currently have the
                 * txg stopped from syncing.
                 */
                VN_RELE_ASYNC(ZTOV(zp),
                    dsl_pool_vnrele_taskq(dmu_objset_pool(os)));
                return (ENOENT);
        }

        /*
         * Write records come in two flavors: immediate and indirect.
         * For small writes it's cheaper to store the data with the
         * log record (immediate); for large writes it's cheaper to
         * sync the data and get a pointer to it (indirect) so that
         * we don't have to write the data twice.
         */
        if (buf != NULL) { /* immediate write */
                rl = zfs_range_lock(zp, off, dlen, RL_READER);
                /* test for truncation needs to be done while range locked */
                if (off >= zp->z_phys->zp_size) {
                        error = ENOENT;
                        goto out;
                }
                VERIFY(0 == dmu_read(os, lr->lr_foid, off, dlen, buf,
                    DMU_READ_NO_PREFETCH));
        } else { /* indirect write */
                uint64_t boff; /* block starting offset */

                /*
                 * Have to lock the whole block to ensure when it's
                 * written out and it's checksum is being calculated
                 * that no one can change the data. We need to re-check
                 * blocksize after we get the lock in case it's changed!
                 */
                for (;;) {
                        if (ISP2(zp->z_blksz)) {
                                boff = P2ALIGN_TYPED(off, zp->z_blksz,
                                    uint64_t);
                        } else {
                                boff = 0;
                        }
                        dlen = zp->z_blksz;
                        rl = zfs_range_lock(zp, boff, dlen, RL_READER);
                        if (zp->z_blksz == dlen)
                                break;
                        zfs_range_unlock(rl);
                }
                /* test for truncation needs to be done while range locked */
                if (off >= zp->z_phys->zp_size) {
                        error = ENOENT;
                        goto out;
                }
                zgd = (zgd_t *)kmem_alloc(sizeof (zgd_t), KM_SLEEP);
                zgd->zgd_rl = rl;
                zgd->zgd_zilog = zfsvfs->z_log;
                zgd->zgd_bp = &lr->lr_blkptr;
                VERIFY(0 == dmu_buf_hold(os, lr->lr_foid, boff, zgd, &db));
                ASSERT(boff == db->db_offset);
                lr->lr_blkoff = off - boff;
                error = dmu_sync(zio, db, &lr->lr_blkptr,
                    lr->lr_common.lrc_txg, zfs_get_done, zgd);
                ASSERT((error && error != EINPROGRESS) ||
                    lr->lr_length <= zp->z_blksz);
                if (error == 0) {
                        /*
                         * dmu_sync() can compress a block of zeros to a null
                         * blkptr but the block size still needs to be passed
                         * through to replay.
                         */
                        BP_SET_LSIZE(&lr->lr_blkptr, db->db_size);
                        zil_add_block(zfsvfs->z_log, &lr->lr_blkptr);
                }

                /*
                 * If we get EINPROGRESS, then we need to wait for a
                 * write IO initiated by dmu_sync() to complete before
                 * we can release this dbuf.  We will finish everything
                 * up in the zfs_get_done() callback.
                 */
                if (error == EINPROGRESS) {
                        return (0);
                } else if (error == EALREADY) {
                        lr->lr_common.lrc_txtype = TX_WRITE2;
                        error = 0;
                }
                dmu_buf_rele(db, zgd);
                kmem_free(zgd, sizeof (zgd_t));
        }
out:
        zfs_range_unlock(rl);
        /*
         * Release the vnode asynchronously as we currently have the
         * txg stopped from syncing.
         */
        VN_RELE_ASYNC(ZTOV(zp), dsl_pool_vnrele_taskq(dmu_objset_pool(os)));
        return (error);
}

/*ARGSUSED*/
static int
zfs_access(vnode_t *vp, int mode, int flag, cred_t *cr,
    caller_context_t *ct)
{
        znode_t *zp = VTOZ(vp);
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        int error;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        if (flag & V_ACE_MASK)
                error = zfs_zaccess(zp, mode, flag, B_FALSE, cr);
        else
                error = zfs_zaccess_rwx(zp, mode, flag, cr);

        ZFS_EXIT(zfsvfs);
        return (error);
}

/*
 * If vnode is for a device return a specfs vnode instead.
 */
static int
specvp_check(vnode_t **vpp, cred_t *cr)
{
        int error = 0;

        if (IS_DEVVP(*vpp)) {
                struct vnode *svp;

                svp = specvp(*vpp, (*vpp)->v_rdev, (*vpp)->v_type, cr);
                VN_RELE(*vpp);
                if (svp == NULL)
                        error = ENOSYS;
                *vpp = svp;
        }
        return (error);
}


/*
 * Lookup an entry in a directory, or an extended attribute directory.
 * If it exists, return a held vnode reference for it.
 *
 *      IN:     dvp     - vnode of directory to search.
 *              nm      - name of entry to lookup.
 *              pnp     - full pathname to lookup [UNUSED].
 *              flags   - LOOKUP_XATTR set if looking for an attribute.
 *              rdir    - root directory vnode [UNUSED].
 *              cr      - credentials of caller.
 *              ct      - caller context
 *              direntflags - directory lookup flags
 *              realpnp - returned pathname.
 *
 *      OUT:    vpp     - vnode of located entry, NULL if not found.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      NA
 */
/* ARGSUSED */
static int
zfs_lookup(vnode_t *dvp, char *nm, vnode_t **vpp, struct componentname *cnp,
    int nameiop, cred_t *cr, kthread_t *td, int flags)
{
        znode_t *zdp = VTOZ(dvp);
        zfsvfs_t *zfsvfs = zdp->z_zfsvfs;
        int     error = 0;
        int *direntflags = NULL;
        void *realpnp = NULL;

        /* fast path */
        if (!(flags & (LOOKUP_XATTR | FIGNORECASE))) {

                if (dvp->v_type != VDIR) {
                        return (ENOTDIR);
                } else if (zdp->z_dbuf == NULL) {
                        return (EIO);
                }

                if (nm[0] == 0 || (nm[0] == '.' && nm[1] == '\0')) {
                        error = zfs_fastaccesschk_execute(zdp, cr);
                        if (!error) {
                                *vpp = dvp;
                                VN_HOLD(*vpp);
                                return (0);
                        }
                        return (error);
                } else {
                        vnode_t *tvp = dnlc_lookup(dvp, nm);

                        if (tvp) {
                                error = zfs_fastaccesschk_execute(zdp, cr);
                                if (error) {
                                        VN_RELE(tvp);
                                        return (error);
                                }
                                if (tvp == DNLC_NO_VNODE) {
                                        VN_RELE(tvp);
                                        return (ENOENT);
                                } else {
                                        *vpp = tvp;
                                        return (specvp_check(vpp, cr));
                                }
                        }
                }
        }

        DTRACE_PROBE2(zfs__fastpath__lookup__miss, vnode_t *, dvp, char *, nm);

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zdp);

        *vpp = NULL;

        if (flags & LOOKUP_XATTR) {
#ifdef TODO
                /*
                 * If the xattr property is off, refuse the lookup request.
                 */
                if (!(zfsvfs->z_vfs->vfs_flag & VFS_XATTR)) {
                        ZFS_EXIT(zfsvfs);
                        return (EINVAL);
                }
#endif

                /*
                 * We don't allow recursive attributes..
                 * Maybe someday we will.
                 */
                if (zdp->z_phys->zp_flags & ZFS_XATTR) {
                        ZFS_EXIT(zfsvfs);
                        return (EINVAL);
                }

                if (error = zfs_get_xattrdir(VTOZ(dvp), vpp, cr, flags)) {
                        ZFS_EXIT(zfsvfs);
                        return (error);
                }

                /*
                 * Do we have permission to get into attribute directory?
                 */

                if (error = zfs_zaccess(VTOZ(*vpp), ACE_EXECUTE, 0,
                    B_FALSE, cr)) {
                        VN_RELE(*vpp);
                        *vpp = NULL;
                }

                ZFS_EXIT(zfsvfs);
                return (error);
        }

        if (dvp->v_type != VDIR) {
                ZFS_EXIT(zfsvfs);
                return (ENOTDIR);
        }

        /*
         * Check accessibility of directory.
         */

        if (error = zfs_zaccess(zdp, ACE_EXECUTE, 0, B_FALSE, cr)) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        if (zfsvfs->z_utf8 && u8_validate(nm, strlen(nm),
            NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                ZFS_EXIT(zfsvfs);
                return (EILSEQ);
        }

        error = zfs_dirlook(zdp, nm, vpp, flags, direntflags, realpnp);
        if (error == 0)
                error = specvp_check(vpp, cr);

        /* Translate errors and add SAVENAME when needed. */
        if (cnp->cn_flags & ISLASTCN) {
                switch (nameiop) {
                case CREATE:
                case RENAME:
                        if (error == ENOENT) {
                                error = EJUSTRETURN;
                                cnp->cn_flags |= SAVENAME;
                                break;
                        }
                        /* FALLTHROUGH */
                case DELETE:
                        if (error == 0)
                                cnp->cn_flags |= SAVENAME;
                        break;
                }
        }
        if (error == 0 && (nm[0] != '.' || nm[1] != '\0')) {
                int ltype = 0;

                if (cnp->cn_flags & ISDOTDOT) {
                        ltype = VOP_ISLOCKED(dvp);
                        VOP_UNLOCK(dvp, 0);
                }
                ZFS_EXIT(zfsvfs);
                error = vn_lock(*vpp, cnp->cn_lkflags);
                if (cnp->cn_flags & ISDOTDOT)
                        vn_lock(dvp, ltype | LK_RETRY);
                if (error != 0) {
                        VN_RELE(*vpp);
                        *vpp = NULL;
                        return (error);
                }
        } else {
                ZFS_EXIT(zfsvfs);
        }

#ifdef FREEBSD_NAMECACHE
        /*
         * Insert name into cache (as non-existent) if appropriate.
         */
        if (error == ENOENT && (cnp->cn_flags & MAKEENTRY) && nameiop != CREATE)
                cache_enter(dvp, *vpp, cnp);
        /*
         * Insert name into cache if appropriate.
         */
        if (error == 0 && (cnp->cn_flags & MAKEENTRY)) {
                if (!(cnp->cn_flags & ISLASTCN) ||
                    (nameiop != DELETE && nameiop != RENAME)) {
                        cache_enter(dvp, *vpp, cnp);
                }
        }
#endif

        return (error);
}

/*
 * Attempt to create a new entry in a directory.  If the entry
 * already exists, truncate the file if permissible, else return
 * an error.  Return the vp of the created or trunc'd file.
 *
 *      IN:     dvp     - vnode of directory to put new file entry in.
 *              name    - name of new file entry.
 *              vap     - attributes of new file.
 *              excl    - flag indicating exclusive or non-exclusive mode.
 *              mode    - mode to open file with.
 *              cr      - credentials of caller.
 *              flag    - large file flag [UNUSED].
 *              ct      - caller context
 *              vsecp   - ACL to be set
 *
 *      OUT:    vpp     - vnode of created or trunc'd entry.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      dvp - ctime|mtime updated if new entry created
 *       vp - ctime|mtime always, atime if new
 */

/* ARGSUSED */
static int
zfs_create(vnode_t *dvp, char *name, vattr_t *vap, int excl, int mode,
    vnode_t **vpp, cred_t *cr, kthread_t *td)
{
        znode_t         *zp, *dzp = VTOZ(dvp);
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        zilog_t         *zilog;
        objset_t        *os;
        zfs_dirlock_t   *dl;
        dmu_tx_t        *tx;
        int             error;
        ksid_t          *ksid;
        uid_t           uid;
        gid_t           gid = crgetgid(cr);
        zfs_acl_ids_t   acl_ids;
        boolean_t       fuid_dirtied;
        void            *vsecp = NULL;
        int             flag = 0;

        /*
         * If we have an ephemeral id, ACL, or XVATTR then
         * make sure file system is at proper version
         */

        ksid = crgetsid(cr, KSID_OWNER);
        if (ksid)
                uid = ksid_getid(ksid);
        else
                uid = crgetuid(cr);
        if (zfsvfs->z_use_fuids == B_FALSE &&
            (vsecp || (vap->va_mask & AT_XVATTR) ||
            IS_EPHEMERAL(crgetuid(cr)) || IS_EPHEMERAL(crgetgid(cr))))
                return (EINVAL);

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(dzp);
        os = zfsvfs->z_os;
        zilog = zfsvfs->z_log;

        if (zfsvfs->z_utf8 && u8_validate(name, strlen(name),
            NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                ZFS_EXIT(zfsvfs);
                return (EILSEQ);
        }

        if (vap->va_mask & AT_XVATTR) {
                if ((error = secpolicy_xvattr(dvp, (xvattr_t *)vap,
                    crgetuid(cr), cr, vap->va_type)) != 0) {
                        ZFS_EXIT(zfsvfs);
                        return (error);
                }
        }
top:
        *vpp = NULL;

        if ((vap->va_mode & S_ISVTX) && secpolicy_vnode_stky_modify(cr))
                vap->va_mode &= ~S_ISVTX;

        if (*name == '\0') {
                /*
                 * Null component name refers to the directory itself.
                 */
                VN_HOLD(dvp);
                zp = dzp;
                dl = NULL;
                error = 0;
        } else {
                /* possible VN_HOLD(zp) */
                int zflg = 0;

                if (flag & FIGNORECASE)
                        zflg |= ZCILOOK;

                error = zfs_dirent_lock(&dl, dzp, name, &zp, zflg,
                    NULL, NULL);
                if (error) {
                        if (strcmp(name, "..") == 0)
                                error = EISDIR;
                        ZFS_EXIT(zfsvfs);
                        return (error);
                }
        }
        if (zp == NULL) {
                uint64_t txtype;

                /*
                 * Create a new file object and update the directory
                 * to reference it.
                 */
                if (error = zfs_zaccess(dzp, ACE_ADD_FILE, 0, B_FALSE, cr)) {
                        goto out;
                }

                /*
                 * We only support the creation of regular files in
                 * extended attribute directories.
                 */
                if ((dzp->z_phys->zp_flags & ZFS_XATTR) &&
                    (vap->va_type != VREG)) {
                        error = EINVAL;
                        goto out;
                }


                if ((error = zfs_acl_ids_create(dzp, 0, vap, cr, vsecp,
                    &acl_ids)) != 0)
                        goto out;
                if (zfs_acl_ids_overquota(zfsvfs, &acl_ids)) {
                        zfs_acl_ids_free(&acl_ids);
                        error = EDQUOT;
                        goto out;
                }

                tx = dmu_tx_create(os);
                dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
                fuid_dirtied = zfsvfs->z_fuid_dirty;
                if (fuid_dirtied)
                        zfs_fuid_txhold(zfsvfs, tx);
                dmu_tx_hold_bonus(tx, dzp->z_id);
                dmu_tx_hold_zap(tx, dzp->z_id, TRUE, name);
                if (acl_ids.z_aclp->z_acl_bytes > ZFS_ACE_SPACE) {
                        dmu_tx_hold_write(tx, DMU_NEW_OBJECT,
                            0, SPA_MAXBLOCKSIZE);
                }
                error = dmu_tx_assign(tx, TXG_NOWAIT);
                if (error) {
                        zfs_acl_ids_free(&acl_ids);
                        zfs_dirent_unlock(dl);
                        if (error == ERESTART) {
                                dmu_tx_wait(tx);
                                dmu_tx_abort(tx);
                                goto top;
                        }
                        dmu_tx_abort(tx);
                        ZFS_EXIT(zfsvfs);
                        return (error);
                }
                zfs_mknode(dzp, vap, tx, cr, 0, &zp, 0, &acl_ids);

                if (fuid_dirtied)
                        zfs_fuid_sync(zfsvfs, tx);

                (void) zfs_link_create(dl, zp, tx, ZNEW);

                txtype = zfs_log_create_txtype(Z_FILE, vsecp, vap);
                if (flag & FIGNORECASE)
                        txtype |= TX_CI;
                zfs_log_create(zilog, tx, txtype, dzp, zp, name,
                    vsecp, acl_ids.z_fuidp, vap);
                zfs_acl_ids_free(&acl_ids);
                dmu_tx_commit(tx);
        } else {
                int aflags = (flag & FAPPEND) ? V_APPEND : 0;

                /*
                 * A directory entry already exists for this name.
                 */
                /*
                 * Can't truncate an existing file if in exclusive mode.
                 */
                if (excl == EXCL) {
                        error = EEXIST;
                        goto out;
                }
                /*
                 * Can't open a directory for writing.
                 */
                if ((ZTOV(zp)->v_type == VDIR) && (mode & S_IWRITE)) {
                        error = EISDIR;
                        goto out;
                }
                /*
                 * Verify requested access to file.
                 */
                if (mode && (error = zfs_zaccess_rwx(zp, mode, aflags, cr))) {
                        goto out;
                }

                mutex_enter(&dzp->z_lock);
                dzp->z_seq++;
                mutex_exit(&dzp->z_lock);

                /*
                 * Truncate regular files if requested.
                 */
                if ((ZTOV(zp)->v_type == VREG) &&
                    (vap->va_mask & AT_SIZE) && (vap->va_size == 0)) {
                        /* we can't hold any locks when calling zfs_freesp() */
                        zfs_dirent_unlock(dl);
                        dl = NULL;
                        error = zfs_freesp(zp, 0, 0, mode, TRUE);
                        if (error == 0) {
                                vnevent_create(ZTOV(zp), ct);
                        }
                }
        }
out:
        if (dl)
                zfs_dirent_unlock(dl);

        if (error) {
                if (zp)
                        VN_RELE(ZTOV(zp));
        } else {
                *vpp = ZTOV(zp);
                error = specvp_check(vpp, cr);
        }

        ZFS_EXIT(zfsvfs);
        return (error);
}

/*
 * Remove an entry from a directory.
 *
 *      IN:     dvp     - vnode of directory to remove entry from.
 *              name    - name of entry to remove.
 *              cr      - credentials of caller.
 *              ct      - caller context
 *              flags   - case flags
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      dvp - ctime|mtime
 *       vp - ctime (if nlink > 0)
 */
/*ARGSUSED*/
static int
zfs_remove(vnode_t *dvp, char *name, cred_t *cr, caller_context_t *ct,
    int flags)
{
        znode_t         *zp, *dzp = VTOZ(dvp);
        znode_t         *xzp = NULL;
        vnode_t         *vp;
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        zilog_t         *zilog;
        uint64_t        acl_obj, xattr_obj;
        zfs_dirlock_t   *dl;
        dmu_tx_t        *tx;
        boolean_t       may_delete_now, delete_now = FALSE;
        boolean_t       unlinked, toobig = FALSE;
        uint64_t        txtype;
        pathname_t      *realnmp = NULL;
        pathname_t      realnm;
        int             error;
        int             zflg = ZEXISTS;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(dzp);
        zilog = zfsvfs->z_log;

        if (flags & FIGNORECASE) {
                zflg |= ZCILOOK;
                pn_alloc(&realnm);
                realnmp = &realnm;
        }

top:
        /*
         * Attempt to lock directory; fail if entry doesn't exist.
         */
        if (error = zfs_dirent_lock(&dl, dzp, name, &zp, zflg,
            NULL, realnmp)) {
                if (realnmp)
                        pn_free(realnmp);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        vp = ZTOV(zp);

        if (error = zfs_zaccess_delete(dzp, zp, cr)) {
                goto out;
        }

        /*
         * Need to use rmdir for removing directories.
         */
        if (vp->v_type == VDIR) {
                error = EPERM;
                goto out;
        }

        vnevent_remove(vp, dvp, name, ct);

        if (realnmp)
                dnlc_remove(dvp, realnmp->pn_buf);
        else
                dnlc_remove(dvp, name);

        may_delete_now = FALSE;

        /*
         * We may delete the znode now, or we may put it in the unlinked set;
         * it depends on whether we're the last link, and on whether there are
         * other holds on the vnode.  So we dmu_tx_hold() the right things to
         * allow for either case.
         */
        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_zap(tx, dzp->z_id, FALSE, name);
        dmu_tx_hold_bonus(tx, zp->z_id);
        if (may_delete_now) {
                toobig =
                    zp->z_phys->zp_size > zp->z_blksz * DMU_MAX_DELETEBLKCNT;
                /* if the file is too big, only hold_free a token amount */
                dmu_tx_hold_free(tx, zp->z_id, 0,
                    (toobig ? DMU_MAX_ACCESS : DMU_OBJECT_END));
        }

        /* are there any extended attributes? */
        if ((xattr_obj = zp->z_phys->zp_xattr) != 0) {
                /* XXX - do we need this if we are deleting? */
                dmu_tx_hold_bonus(tx, xattr_obj);
        }

        /* are there any additional acls */
        if ((acl_obj = zp->z_phys->zp_acl.z_acl_extern_obj) != 0 &&
            may_delete_now)
                dmu_tx_hold_free(tx, acl_obj, 0, DMU_OBJECT_END);

        /* charge as an update -- would be nice not to charge at all */
        dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);

        error = dmu_tx_assign(tx, TXG_NOWAIT);
        if (error) {
                zfs_dirent_unlock(dl);
                VN_RELE(vp);
                if (error == ERESTART) {
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto top;
                }
                if (realnmp)
                        pn_free(realnmp);
                dmu_tx_abort(tx);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        /*
         * Remove the directory entry.
         */
        error = zfs_link_destroy(dl, zp, tx, zflg, &unlinked);

        if (error) {
                dmu_tx_commit(tx);
                goto out;
        }

        if (0 && unlinked) {
                VI_LOCK(vp);
                delete_now = may_delete_now && !toobig &&
                    vp->v_count == 1 && !vn_has_cached_data(vp) &&
                    zp->z_phys->zp_xattr == xattr_obj &&
                    zp->z_phys->zp_acl.z_acl_extern_obj == acl_obj;
                VI_UNLOCK(vp);
        }

        if (delete_now) {
                if (zp->z_phys->zp_xattr) {
                        error = zfs_zget(zfsvfs, zp->z_phys->zp_xattr, &xzp);
                        ASSERT3U(error, ==, 0);
                        ASSERT3U(xzp->z_phys->zp_links, ==, 2);
                        dmu_buf_will_dirty(xzp->z_dbuf, tx);
                        mutex_enter(&xzp->z_lock);
                        xzp->z_unlinked = 1;
                        xzp->z_phys->zp_links = 0;
                        mutex_exit(&xzp->z_lock);
                        zfs_unlinked_add(xzp, tx);
                        zp->z_phys->zp_xattr = 0; /* probably unnecessary */
                }
                mutex_enter(&zp->z_lock);
                VI_LOCK(vp);
                vp->v_count--;
                ASSERT3U(vp->v_count, ==, 0);
                VI_UNLOCK(vp);
                mutex_exit(&zp->z_lock);
                zfs_znode_delete(zp, tx);
        } else if (unlinked) {
                zfs_unlinked_add(zp, tx);
        }

        txtype = TX_REMOVE;
        if (flags & FIGNORECASE)
                txtype |= TX_CI;
        zfs_log_remove(zilog, tx, txtype, dzp, name);

        dmu_tx_commit(tx);
out:
        if (realnmp)
                pn_free(realnmp);

        zfs_dirent_unlock(dl);

        if (!delete_now) {
                VN_RELE(vp);
        } else if (xzp) {
                /* this rele is delayed to prevent nesting transactions */
                VN_RELE(ZTOV(xzp));
        }

        ZFS_EXIT(zfsvfs);
        return (error);
}

/*
 * Create a new directory and insert it into dvp using the name
 * provided.  Return a pointer to the inserted directory.
 *
 *      IN:     dvp     - vnode of directory to add subdir to.
 *              dirname - name of new directory.
 *              vap     - attributes of new directory.
 *              cr      - credentials of caller.
 *              ct      - caller context
 *              vsecp   - ACL to be set
 *
 *      OUT:    vpp     - vnode of created directory.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      dvp - ctime|mtime updated
 *       vp - ctime|mtime|atime updated
 */
/*ARGSUSED*/
static int
zfs_mkdir(vnode_t *dvp, char *dirname, vattr_t *vap, vnode_t **vpp, cred_t *cr,
    caller_context_t *ct, int flags, vsecattr_t *vsecp)
{
        znode_t         *zp, *dzp = VTOZ(dvp);
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        zilog_t         *zilog;
        zfs_dirlock_t   *dl;
        uint64_t        txtype;
        dmu_tx_t        *tx;
        int             error;
        int             zf = ZNEW;
        ksid_t          *ksid;
        uid_t           uid;
        gid_t           gid = crgetgid(cr);
        zfs_acl_ids_t   acl_ids;
        boolean_t       fuid_dirtied;

        ASSERT(vap->va_type == VDIR);

        /*
         * If we have an ephemeral id, ACL, or XVATTR then
         * make sure file system is at proper version
         */

        ksid = crgetsid(cr, KSID_OWNER);
        if (ksid)
                uid = ksid_getid(ksid);
        else
                uid = crgetuid(cr);
        if (zfsvfs->z_use_fuids == B_FALSE &&
            (vsecp || (vap->va_mask & AT_XVATTR) || IS_EPHEMERAL(crgetuid(cr))||
            IS_EPHEMERAL(crgetgid(cr))))
                return (EINVAL);

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(dzp);
        zilog = zfsvfs->z_log;

        if (dzp->z_phys->zp_flags & ZFS_XATTR) {
                ZFS_EXIT(zfsvfs);
                return (EINVAL);
        }

        if (zfsvfs->z_utf8 && u8_validate(dirname,
            strlen(dirname), NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                ZFS_EXIT(zfsvfs);
                return (EILSEQ);
        }
        if (flags & FIGNORECASE)
                zf |= ZCILOOK;

        if (vap->va_mask & AT_XVATTR)
                if ((error = secpolicy_xvattr(dvp, (xvattr_t *)vap,
                    crgetuid(cr), cr, vap->va_type)) != 0) {
                        ZFS_EXIT(zfsvfs);
                        return (error);
                }

        /*
         * First make sure the new directory doesn't exist.
         */
top:
        *vpp = NULL;

        if (error = zfs_dirent_lock(&dl, dzp, dirname, &zp, zf,
            NULL, NULL)) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        if (error = zfs_zaccess(dzp, ACE_ADD_SUBDIRECTORY, 0, B_FALSE, cr)) {
                zfs_dirent_unlock(dl);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        if ((error = zfs_acl_ids_create(dzp, 0, vap, cr, vsecp,
            &acl_ids)) != 0) {
                zfs_dirent_unlock(dl);
                ZFS_EXIT(zfsvfs);
                return (error);
        }
        if (zfs_acl_ids_overquota(zfsvfs, &acl_ids)) {
                zfs_acl_ids_free(&acl_ids);
                zfs_dirent_unlock(dl);
                ZFS_EXIT(zfsvfs);
                return (EDQUOT);
        }

        /*
         * Add a new entry to the directory.
         */
        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_zap(tx, dzp->z_id, TRUE, dirname);
        dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
        fuid_dirtied = zfsvfs->z_fuid_dirty;
        if (fuid_dirtied)
                zfs_fuid_txhold(zfsvfs, tx);
        if (acl_ids.z_aclp->z_acl_bytes > ZFS_ACE_SPACE)
                dmu_tx_hold_write(tx, DMU_NEW_OBJECT,
                    0, SPA_MAXBLOCKSIZE);
        error = dmu_tx_assign(tx, TXG_NOWAIT);
        if (error) {
                zfs_acl_ids_free(&acl_ids);
                zfs_dirent_unlock(dl);
                if (error == ERESTART) {
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto top;
                }
                dmu_tx_abort(tx);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        /*
         * Create new node.
         */
        zfs_mknode(dzp, vap, tx, cr, 0, &zp, 0, &acl_ids);

        if (fuid_dirtied)
                zfs_fuid_sync(zfsvfs, tx);
        /*
         * Now put new name in parent dir.
         */
        (void) zfs_link_create(dl, zp, tx, ZNEW);

        *vpp = ZTOV(zp);

        txtype = zfs_log_create_txtype(Z_DIR, vsecp, vap);
        if (flags & FIGNORECASE)
                txtype |= TX_CI;
        zfs_log_create(zilog, tx, txtype, dzp, zp, dirname, vsecp,
            acl_ids.z_fuidp, vap);

        zfs_acl_ids_free(&acl_ids);
        dmu_tx_commit(tx);

        zfs_dirent_unlock(dl);

        ZFS_EXIT(zfsvfs);
        return (0);
}

/*
 * Remove a directory subdir entry.  If the current working
 * directory is the same as the subdir to be removed, the
 * remove will fail.
 *
 *      IN:     dvp     - vnode of directory to remove from.
 *              name    - name of directory to be removed.
 *              cwd     - vnode of current working directory.
 *              cr      - credentials of caller.
 *              ct      - caller context
 *              flags   - case flags
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      dvp - ctime|mtime updated
 */
/*ARGSUSED*/
static int
zfs_rmdir(vnode_t *dvp, char *name, vnode_t *cwd, cred_t *cr,
    caller_context_t *ct, int flags)
{
        znode_t         *dzp = VTOZ(dvp);
        znode_t         *zp;
        vnode_t         *vp;
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        zilog_t         *zilog;
        zfs_dirlock_t   *dl;
        dmu_tx_t        *tx;
        int             error;
        int             zflg = ZEXISTS;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(dzp);
        zilog = zfsvfs->z_log;

        if (flags & FIGNORECASE)
                zflg |= ZCILOOK;
top:
        zp = NULL;

        /*
         * Attempt to lock directory; fail if entry doesn't exist.
         */
        if (error = zfs_dirent_lock(&dl, dzp, name, &zp, zflg,
            NULL, NULL)) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        vp = ZTOV(zp);

        if (error = zfs_zaccess_delete(dzp, zp, cr)) {
                goto out;
        }

        if (vp->v_type != VDIR) {
                error = ENOTDIR;
                goto out;
        }

        if (vp == cwd) {
                error = EINVAL;
                goto out;
        }

        vnevent_rmdir(vp, dvp, name, ct);

        /*
         * Grab a lock on the directory to make sure that noone is
         * trying to add (or lookup) entries while we are removing it.
         */
        rw_enter(&zp->z_name_lock, RW_WRITER);

        /*
         * Grab a lock on the parent pointer to make sure we play well
         * with the treewalk and directory rename code.
         */
        rw_enter(&zp->z_parent_lock, RW_WRITER);

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_zap(tx, dzp->z_id, FALSE, name);
        dmu_tx_hold_bonus(tx, zp->z_id);
        dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
        error = dmu_tx_assign(tx, TXG_NOWAIT);
        if (error) {
                rw_exit(&zp->z_parent_lock);
                rw_exit(&zp->z_name_lock);
                zfs_dirent_unlock(dl);
                VN_RELE(vp);
                if (error == ERESTART) {
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto top;
                }
                dmu_tx_abort(tx);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

#ifdef FREEBSD_NAMECACHE
        cache_purge(dvp);
#endif

        error = zfs_link_destroy(dl, zp, tx, zflg, NULL);

        if (error == 0) {
                uint64_t txtype = TX_RMDIR;
                if (flags & FIGNORECASE)
                        txtype |= TX_CI;
                zfs_log_remove(zilog, tx, txtype, dzp, name);
        }

        dmu_tx_commit(tx);

        rw_exit(&zp->z_parent_lock);
        rw_exit(&zp->z_name_lock);
#ifdef FREEBSD_NAMECACHE
        cache_purge(vp);
#endif
out:
        zfs_dirent_unlock(dl);

        VN_RELE(vp);

        ZFS_EXIT(zfsvfs);
        return (error);
}

/*
 * Read as many directory entries as will fit into the provided
 * buffer from the given directory cursor position (specified in
 * the uio structure.
 *
 *      IN:     vp      - vnode of directory to read.
 *              uio     - structure supplying read location, range info,
 *                        and return buffer.
 *              cr      - credentials of caller.
 *              ct      - caller context
 *              flags   - case flags
 *
 *      OUT:    uio     - updated offset and range, buffer filled.
 *              eofp    - set to true if end-of-file detected.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      vp - atime updated
 *
 * Note that the low 4 bits of the cookie returned by zap is always zero.
 * This allows us to use the low range for "special" directory entries:
 * We use 0 for '.', and 1 for '..'.  If this is the root of the filesystem,
 * we use the offset 2 for the '.zfs' directory.
 */
/* ARGSUSED */
static int
zfs_readdir(vnode_t *vp, uio_t *uio, cred_t *cr, int *eofp, int *ncookies, u_long **cookies)
{
        znode_t         *zp = VTOZ(vp);
        iovec_t         *iovp;
        edirent_t       *eodp;
        dirent64_t      *odp;
        zfsvfs_t        *zfsvfs = zp->z_zfsvfs;
        objset_t        *os;
        caddr_t         outbuf;
        size_t          bufsize;
        zap_cursor_t    zc;
        zap_attribute_t zap;
        uint_t          bytes_wanted;
        uint64_t        offset; /* must be unsigned; checks for < 1 */
        int             local_eof;
        int             outcount;
        int             error;
        uint8_t         prefetch;
        boolean_t       check_sysattrs;
        uint8_t         type;
        int             ncooks;
        u_long          *cooks = NULL;
        int             flags = 0;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        /*
         * If we are not given an eof variable,
         * use a local one.
         */
        if (eofp == NULL)
                eofp = &local_eof;

        /*
         * Check for valid iov_len.
         */
        if (uio->uio_iov->iov_len <= 0) {
                ZFS_EXIT(zfsvfs);
                return (EINVAL);
        }

        /*
         * Quit if directory has been removed (posix)
         */
        if ((*eofp = zp->z_unlinked) != 0) {
                ZFS_EXIT(zfsvfs);
                return (0);
        }

        error = 0;
        os = zfsvfs->z_os;
        offset = uio->uio_loffset;
        prefetch = zp->z_zn_prefetch;

        /*
         * Initialize the iterator cursor.
         */
        if (offset <= 3) {
                /*
                 * Start iteration from the beginning of the directory.
                 */
                zap_cursor_init(&zc, os, zp->z_id);
        } else {
                /*
                 * The offset is a serialized cursor.
                 */
                zap_cursor_init_serialized(&zc, os, zp->z_id, offset);
        }

        /*
         * Get space to change directory entries into fs independent format.
         */
        iovp = uio->uio_iov;
        bytes_wanted = iovp->iov_len;
        if (uio->uio_segflg != UIO_SYSSPACE || uio->uio_iovcnt != 1) {
                bufsize = bytes_wanted;
                outbuf = kmem_alloc(bufsize, KM_SLEEP);
                odp = (struct dirent64 *)outbuf;
        } else {
                bufsize = bytes_wanted;
                odp = (struct dirent64 *)iovp->iov_base;
        }
        eodp = (struct edirent *)odp;

        if (ncookies != NULL) {
                /*
                 * Minimum entry size is dirent size and 1 byte for a file name.
                 */
                ncooks = uio->uio_resid / (sizeof(struct dirent) - sizeof(((struct dirent *)NULL)->d_name) + 1);
                cooks = malloc(ncooks * sizeof(u_long), M_TEMP, M_WAITOK);
                *cookies = cooks;
                *ncookies = ncooks;
        }
        /*
         * If this VFS supports the system attribute view interface; and
         * we're looking at an extended attribute directory; and we care
         * about normalization conflicts on this vfs; then we must check
         * for normalization conflicts with the sysattr name space.
         */
#ifdef TODO
        check_sysattrs = vfs_has_feature(vp->v_vfsp, VFSFT_SYSATTR_VIEWS) &&
            (vp->v_flag & V_XATTRDIR) && zfsvfs->z_norm &&
            (flags & V_RDDIR_ENTFLAGS);
#else
        check_sysattrs = 0;
#endif

        /*
         * Transform to file-system independent format
         */
        outcount = 0;
        while (outcount < bytes_wanted) {
                ino64_t objnum;
                ushort_t reclen;
                off64_t *next;

                /*
                 * Special case `.', `..', and `.zfs'.
                 */
                if (offset == 0) {
                        (void) strcpy(zap.za_name, ".");
                        zap.za_normalization_conflict = 0;
                        objnum = zp->z_id;
                        type = DT_DIR;
                } else if (offset == 1) {
                        (void) strcpy(zap.za_name, "..");
                        zap.za_normalization_conflict = 0;
                        objnum = zp->z_phys->zp_parent;
                        type = DT_DIR;
                } else if (offset == 2 && zfs_show_ctldir(zp)) {
                        (void) strcpy(zap.za_name, ZFS_CTLDIR_NAME);
                        zap.za_normalization_conflict = 0;
                        objnum = ZFSCTL_INO_ROOT;
                        type = DT_DIR;
                } else {
                        /*
                         * Grab next entry.
                         */
                        if (error = zap_cursor_retrieve(&zc, &zap)) {
                                if ((*eofp = (error == ENOENT)) != 0)
                                        break;
                                else
                                        goto update;
                        }

                        if (zap.za_integer_length != 8 ||
                            zap.za_num_integers != 1) {
                                cmn_err(CE_WARN, "zap_readdir: bad directory "
                                    "entry, obj = %lld, offset = %lld\n",
                                    (u_longlong_t)zp->z_id,
                                    (u_longlong_t)offset);
                                error = ENXIO;
                                goto update;
                        }

                        objnum = ZFS_DIRENT_OBJ(zap.za_first_integer);
                        /*
                         * MacOS X can extract the object type here such as:
                         * uint8_t type = ZFS_DIRENT_TYPE(zap.za_first_integer);
                         */
                        type = ZFS_DIRENT_TYPE(zap.za_first_integer);

                        if (check_sysattrs && !zap.za_normalization_conflict) {
#ifdef TODO
                                zap.za_normalization_conflict =
                                    xattr_sysattr_casechk(zap.za_name);
#else
                                panic("%s:%u: TODO", __func__, __LINE__);
#endif
                        }
                }

                if (flags & V_RDDIR_ACCFILTER) {
                        /*
                         * If we have no access at all, don't include
                         * this entry in the returned information
                         */
                        znode_t *ezp;
                        if (zfs_zget(zp->z_zfsvfs, objnum, &ezp) != 0)
                                goto skip_entry;
                        if (!zfs_has_access(ezp, cr)) {
                                VN_RELE(ZTOV(ezp));
                                goto skip_entry;
                        }
                        VN_RELE(ZTOV(ezp));
                }

                if (flags & V_RDDIR_ENTFLAGS)
                        reclen = EDIRENT_RECLEN(strlen(zap.za_name));
                else
                        reclen = DIRENT64_RECLEN(strlen(zap.za_name));

                /*
                 * Will this entry fit in the buffer?
                 */
                if (outcount + reclen > bufsize) {
                        /*
                         * Did we manage to fit anything in the buffer?
                         */
                        if (!outcount) {
                                error = EINVAL;
                                goto update;
                        }
                        break;
                }
                if (flags & V_RDDIR_ENTFLAGS) {
                        /*
                         * Add extended flag entry:
                         */
                        eodp->ed_ino = objnum;
                        eodp->ed_reclen = reclen;
                        /* NOTE: ed_off is the offset for the *next* entry */
                        next = &(eodp->ed_off);
                        eodp->ed_eflags = zap.za_normalization_conflict ?
                            ED_CASE_CONFLICT : 0;
                        (void) strncpy(eodp->ed_name, zap.za_name,
                            EDIRENT_NAMELEN(reclen));
                        eodp = (edirent_t *)((intptr_t)eodp + reclen);
                } else {
                        /*
                         * Add normal entry:
                         */
                        odp->d_ino = objnum;
                        odp->d_reclen = reclen;
                        odp->d_namlen = strlen(zap.za_name);
                        (void) strlcpy(odp->d_name, zap.za_name, odp->d_namlen + 1);
                        odp->d_type = type;
                        odp = (dirent64_t *)((intptr_t)odp + reclen);
                }
                outcount += reclen;

                ASSERT(outcount <= bufsize);

                /* Prefetch znode */
                if (prefetch)
                        dmu_prefetch(os, objnum, 0, 0);

        skip_entry:
                /*
                 * Move to the next entry, fill in the previous offset.
                 */
                if (offset > 2 || (offset == 2 && !zfs_show_ctldir(zp))) {
                        zap_cursor_advance(&zc);
                        offset = zap_cursor_serialize(&zc);
                } else {
                        offset += 1;
                }

                if (cooks != NULL) {
                        *cooks++ = offset;
                        ncooks--;
                        KASSERT(ncooks >= 0, ("ncookies=%d", ncooks));
                }
        }
        zp->z_zn_prefetch = B_FALSE; /* a lookup will re-enable pre-fetching */

        /* Subtract unused cookies */
        if (ncookies != NULL)
                *ncookies -= ncooks;

        if (uio->uio_segflg == UIO_SYSSPACE && uio->uio_iovcnt == 1) {
                iovp->iov_base += outcount;
                iovp->iov_len -= outcount;
                uio->uio_resid -= outcount;
        } else if (error = uiomove(outbuf, (long)outcount, UIO_READ, uio)) {
                /*
                 * Reset the pointer.
                 */
                offset = uio->uio_loffset;
        }

update:
        zap_cursor_fini(&zc);
        if (uio->uio_segflg != UIO_SYSSPACE || uio->uio_iovcnt != 1)
                kmem_free(outbuf, bufsize);

        if (error == ENOENT)
                error = 0;

        ZFS_ACCESSTIME_STAMP(zfsvfs, zp);

        uio->uio_loffset = offset;
        ZFS_EXIT(zfsvfs);
        if (error != 0 && cookies != NULL) {
                free(*cookies, M_TEMP);
                *cookies = NULL;
                *ncookies = 0;
        }
        return (error);
}

ulong_t zfs_fsync_sync_cnt = 4;

static int
zfs_fsync(vnode_t *vp, int syncflag, cred_t *cr, caller_context_t *ct)
{
        znode_t *zp = VTOZ(vp);
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;

        (void) tsd_set(zfs_fsyncer_key, (void *)zfs_fsync_sync_cnt);

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);
        zil_commit(zfsvfs->z_log, zp->z_last_itx, zp->z_id);
        ZFS_EXIT(zfsvfs);
        return (0);
}


/*
 * Get the requested file attributes and place them in the provided
 * vattr structure.
 *
 *      IN:     vp      - vnode of file.
 *              vap     - va_mask identifies requested attributes.
 *                        If AT_XVATTR set, then optional attrs are requested
 *              flags   - ATTR_NOACLCHECK (CIFS server context)
 *              cr      - credentials of caller.
 *              ct      - caller context
 *
 *      OUT:    vap     - attribute values.
 *
 *      RETURN: 0 (always succeeds)
 */
/* ARGSUSED */
static int
zfs_getattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *cr,
    caller_context_t *ct)
{
        znode_t *zp = VTOZ(vp);
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        znode_phys_t *pzp;
        int     error = 0;
        uint32_t blksize;
        u_longlong_t nblocks;
        uint64_t links;
        xvattr_t *xvap = (xvattr_t *)vap;       /* vap may be an xvattr_t * */
        xoptattr_t *xoap = NULL;
        boolean_t skipaclchk = (flags & ATTR_NOACLCHECK) ? B_TRUE : B_FALSE;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);
        pzp = zp->z_phys;

        /*
         * If ACL is trivial don't bother looking for ACE_READ_ATTRIBUTES.
         * Also, if we are the owner don't bother, since owner should
         * always be allowed to read basic attributes of file.
         */
        if (!(pzp->zp_flags & ZFS_ACL_TRIVIAL) &&
            (pzp->zp_uid != crgetuid(cr))) {
                if (error = zfs_zaccess(zp, ACE_READ_ATTRIBUTES, 0,
                    skipaclchk, cr)) {
                        ZFS_EXIT(zfsvfs);
                        return (error);
                }
        }

        /*
         * Return all attributes.  It's cheaper to provide the answer
         * than to determine whether we were asked the question.
         */

        mutex_enter(&zp->z_lock);
        vap->va_type = IFTOVT(pzp->zp_mode);
        vap->va_mode = pzp->zp_mode & ~S_IFMT;
        zfs_fuid_map_ids(zp, cr, &vap->va_uid, &vap->va_gid);
//      vap->va_fsid = zp->z_zfsvfs->z_vfs->vfs_dev;
        vap->va_nodeid = zp->z_id;
        if ((vp->v_flag & VROOT) && zfs_show_ctldir(zp))
                links = pzp->zp_links + 1;
        else
                links = pzp->zp_links;
        vap->va_nlink = MIN(links, UINT32_MAX); /* nlink_t limit! */
        vap->va_size = pzp->zp_size;
        vap->va_fsid = vp->v_mount->mnt_stat.f_fsid.val[0];
        vap->va_rdev = zfs_cmpldev(pzp->zp_rdev);
        vap->va_seq = zp->z_seq;
        vap->va_flags = 0;      /* FreeBSD: Reset chflags(2) flags. */

        /*
         * Add in any requested optional attributes and the create time.
         * Also set the corresponding bits in the returned attribute bitmap.
         */
        if ((xoap = xva_getxoptattr(xvap)) != NULL && zfsvfs->z_use_fuids) {
                if (XVA_ISSET_REQ(xvap, XAT_ARCHIVE)) {
                        xoap->xoa_archive =
                            ((pzp->zp_flags & ZFS_ARCHIVE) != 0);
                        XVA_SET_RTN(xvap, XAT_ARCHIVE);
                }

                if (XVA_ISSET_REQ(xvap, XAT_READONLY)) {
                        xoap->xoa_readonly =
                            ((pzp->zp_flags & ZFS_READONLY) != 0);
                        XVA_SET_RTN(xvap, XAT_READONLY);
                }

                if (XVA_ISSET_REQ(xvap, XAT_SYSTEM)) {
                        xoap->xoa_system =
                            ((pzp->zp_flags & ZFS_SYSTEM) != 0);
                        XVA_SET_RTN(xvap, XAT_SYSTEM);
                }

                if (XVA_ISSET_REQ(xvap, XAT_HIDDEN)) {
                        xoap->xoa_hidden =
                            ((pzp->zp_flags & ZFS_HIDDEN) != 0);
                        XVA_SET_RTN(xvap, XAT_HIDDEN);
                }

                if (XVA_ISSET_REQ(xvap, XAT_NOUNLINK)) {
                        xoap->xoa_nounlink =
                            ((pzp->zp_flags & ZFS_NOUNLINK) != 0);
                        XVA_SET_RTN(xvap, XAT_NOUNLINK);
                }

                if (XVA_ISSET_REQ(xvap, XAT_IMMUTABLE)) {
                        xoap->xoa_immutable =
                            ((pzp->zp_flags & ZFS_IMMUTABLE) != 0);
                        XVA_SET_RTN(xvap, XAT_IMMUTABLE);
                }

                if (XVA_ISSET_REQ(xvap, XAT_APPENDONLY)) {
                        xoap->xoa_appendonly =
                            ((pzp->zp_flags & ZFS_APPENDONLY) != 0);
                        XVA_SET_RTN(xvap, XAT_APPENDONLY);
                }

                if (XVA_ISSET_REQ(xvap, XAT_NODUMP)) {
                        xoap->xoa_nodump =
                            ((pzp->zp_flags & ZFS_NODUMP) != 0);
                        XVA_SET_RTN(xvap, XAT_NODUMP);
                }

                if (XVA_ISSET_REQ(xvap, XAT_OPAQUE)) {
                        xoap->xoa_opaque =
                            ((pzp->zp_flags & ZFS_OPAQUE) != 0);
                        XVA_SET_RTN(xvap, XAT_OPAQUE);
                }

                if (XVA_ISSET_REQ(xvap, XAT_AV_QUARANTINED)) {
                        xoap->xoa_av_quarantined =
                            ((pzp->zp_flags & ZFS_AV_QUARANTINED) != 0);
                        XVA_SET_RTN(xvap, XAT_AV_QUARANTINED);
                }

                if (XVA_ISSET_REQ(xvap, XAT_AV_MODIFIED)) {
                        xoap->xoa_av_modified =
                            ((pzp->zp_flags & ZFS_AV_MODIFIED) != 0);
                        XVA_SET_RTN(xvap, XAT_AV_MODIFIED);
                }

                if (XVA_ISSET_REQ(xvap, XAT_AV_SCANSTAMP) &&
                    vp->v_type == VREG &&
                    (pzp->zp_flags & ZFS_BONUS_SCANSTAMP)) {
                        size_t len;
                        dmu_object_info_t doi;

                        /*
                         * Only VREG files have anti-virus scanstamps, so we
                         * won't conflict with symlinks in the bonus buffer.
                         */
                        dmu_object_info_from_db(zp->z_dbuf, &doi);
                        len = sizeof (xoap->xoa_av_scanstamp) +
                            sizeof (znode_phys_t);
                        if (len <= doi.doi_bonus_size) {
                                /*
                                 * pzp points to the start of the
                                 * znode_phys_t. pzp + 1 points to the
                                 * first byte after the znode_phys_t.
                                 */
                                (void) memcpy(xoap->xoa_av_scanstamp,
                                    pzp + 1,
                                    sizeof (xoap->xoa_av_scanstamp));
                                XVA_SET_RTN(xvap, XAT_AV_SCANSTAMP);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_CREATETIME)) {
                        ZFS_TIME_DECODE(&xoap->xoa_createtime, pzp->zp_crtime);
                        XVA_SET_RTN(xvap, XAT_CREATETIME);
                }
        }

        ZFS_TIME_DECODE(&vap->va_atime, pzp->zp_atime);
        ZFS_TIME_DECODE(&vap->va_mtime, pzp->zp_mtime);
        ZFS_TIME_DECODE(&vap->va_ctime, pzp->zp_ctime);
        ZFS_TIME_DECODE(&vap->va_birthtime, pzp->zp_crtime);

        mutex_exit(&zp->z_lock);

        dmu_object_size_from_db(zp->z_dbuf, &blksize, &nblocks);
        vap->va_blksize = blksize;
        vap->va_bytes = nblocks << 9;   /* nblocks * 512 */

        if (zp->z_blksz == 0) {
                /*
                 * Block size hasn't been set; suggest maximal I/O transfers.
                 */
                vap->va_blksize = zfsvfs->z_max_blksz;
        }

        ZFS_EXIT(zfsvfs);
        return (0);
}

/*
 * Set the file attributes to the values contained in the
 * vattr structure.
 *
 *      IN:     vp      - vnode of file to be modified.
 *              vap     - new attribute values.
 *                        If AT_XVATTR set, then optional attrs are being set
 *              flags   - ATTR_UTIME set if non-default time values provided.
 *                      - ATTR_NOACLCHECK (CIFS context only).
 *              cr      - credentials of caller.
 *              ct      - caller context
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      vp - ctime updated, mtime updated if size changed.
 */
/* ARGSUSED */
static int
zfs_setattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *cr,
        caller_context_t *ct)
{
        znode_t         *zp = VTOZ(vp);
        znode_phys_t    *pzp;
        zfsvfs_t        *zfsvfs = zp->z_zfsvfs;
        zilog_t         *zilog;
        dmu_tx_t        *tx;
        vattr_t         oldva;
        xvattr_t        tmpxvattr;
        uint_t          mask = vap->va_mask;
        uint_t          saved_mask;
        uint64_t        saved_mode;
        int             trim_mask = 0;
        uint64_t        new_mode;
        uint64_t        new_uid, new_gid;
        znode_t         *attrzp;
        int             need_policy = FALSE;
        int             err;
        zfs_fuid_info_t *fuidp = NULL;
        xvattr_t *xvap = (xvattr_t *)vap;       /* vap may be an xvattr_t * */
        xoptattr_t      *xoap;
        zfs_acl_t       *aclp = NULL;
        boolean_t skipaclchk = (flags & ATTR_NOACLCHECK) ? B_TRUE : B_FALSE;
        boolean_t fuid_dirtied = B_FALSE;

        if (mask == 0)
                return (0);

        if (mask & AT_NOSET)
                return (EINVAL);

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        pzp = zp->z_phys;
        zilog = zfsvfs->z_log;

        /*
         * Make sure that if we have ephemeral uid/gid or xvattr specified
         * that file system is at proper version level
         */

        if (zfsvfs->z_use_fuids == B_FALSE &&
            (((mask & AT_UID) && IS_EPHEMERAL(vap->va_uid)) ||
            ((mask & AT_GID) && IS_EPHEMERAL(vap->va_gid)) ||
            (mask & AT_XVATTR))) {
                ZFS_EXIT(zfsvfs);
                return (EINVAL);
        }

        if (mask & AT_SIZE && vp->v_type == VDIR) {
                ZFS_EXIT(zfsvfs);
                return (EISDIR);
        }

        if (mask & AT_SIZE && vp->v_type != VREG && vp->v_type != VFIFO) {
                ZFS_EXIT(zfsvfs);
                return (EINVAL);
        }

        /*
         * If this is an xvattr_t, then get a pointer to the structure of
         * optional attributes.  If this is NULL, then we have a vattr_t.
         */
        xoap = xva_getxoptattr(xvap);

        xva_init(&tmpxvattr);

        /*
         * Immutable files can only alter immutable bit and atime
         */
        if ((pzp->zp_flags & ZFS_IMMUTABLE) &&
            ((mask & (AT_SIZE|AT_UID|AT_GID|AT_MTIME|AT_MODE)) ||
            ((mask & AT_XVATTR) && XVA_ISSET_REQ(xvap, XAT_CREATETIME)))) {
                ZFS_EXIT(zfsvfs);
                return (EPERM);
        }

        if ((mask & AT_SIZE) && (pzp->zp_flags & ZFS_READONLY)) {
                ZFS_EXIT(zfsvfs);
                return (EPERM);
        }

        /*
         * Verify timestamps doesn't overflow 32 bits.
         * ZFS can handle large timestamps, but 32bit syscalls can't
         * handle times greater than 2039.  This check should be removed
         * once large timestamps are fully supported.
         */
        if (mask & (AT_ATIME | AT_MTIME)) {
                if (((mask & AT_ATIME) && TIMESPEC_OVERFLOW(&vap->va_atime)) ||
                    ((mask & AT_MTIME) && TIMESPEC_OVERFLOW(&vap->va_mtime))) {
                        ZFS_EXIT(zfsvfs);
                        return (EOVERFLOW);
                }
        }

top:
        attrzp = NULL;

        /* Can this be moved to before the top label? */
        if (zfsvfs->z_vfs->vfs_flag & VFS_RDONLY) {
                ZFS_EXIT(zfsvfs);
                return (EROFS);
        }

        /*
         * First validate permissions
         */

        if (mask & AT_SIZE) {
                err = zfs_zaccess(zp, ACE_WRITE_DATA, 0, skipaclchk, cr);
                if (err) {
                        ZFS_EXIT(zfsvfs);
                        return (err);
                }
                /*
                 * XXX - Note, we are not providing any open
                 * mode flags here (like FNDELAY), so we may
                 * block if there are locks present... this
                 * should be addressed in openat().
                 */
                /* XXX - would it be OK to generate a log record here? */
                err = zfs_freesp(zp, vap->va_size, 0, 0, FALSE);
                if (err) {
                        ZFS_EXIT(zfsvfs);
                        return (err);
                }
        }

        if (mask & (AT_ATIME|AT_MTIME) ||
            ((mask & AT_XVATTR) && (XVA_ISSET_REQ(xvap, XAT_HIDDEN) ||
            XVA_ISSET_REQ(xvap, XAT_READONLY) ||
            XVA_ISSET_REQ(xvap, XAT_ARCHIVE) ||
            XVA_ISSET_REQ(xvap, XAT_CREATETIME) ||
            XVA_ISSET_REQ(xvap, XAT_SYSTEM))))
                need_policy = zfs_zaccess(zp, ACE_WRITE_ATTRIBUTES, 0,
                    skipaclchk, cr);

        if (mask & (AT_UID|AT_GID)) {
                int     idmask = (mask & (AT_UID|AT_GID));
                int     take_owner;
                int     take_group;

                /*
                 * NOTE: even if a new mode is being set,
                 * we may clear S_ISUID/S_ISGID bits.
                 */

                if (!(mask & AT_MODE))
                        vap->va_mode = pzp->zp_mode;

                /*
                 * Take ownership or chgrp to group we are a member of
                 */

                take_owner = (mask & AT_UID) && (vap->va_uid == crgetuid(cr));
                take_group = (mask & AT_GID) &&
                    zfs_groupmember(zfsvfs, vap->va_gid, cr);

                /*
                 * If both AT_UID and AT_GID are set then take_owner and
                 * take_group must both be set in order to allow taking
                 * ownership.
                 *
                 * Otherwise, send the check through secpolicy_vnode_setattr()
                 *
                 */

                if (((idmask == (AT_UID|AT_GID)) && take_owner && take_group) ||
                    ((idmask == AT_UID) && take_owner) ||
                    ((idmask == AT_GID) && take_group)) {
                        if (zfs_zaccess(zp, ACE_WRITE_OWNER, 0,
                            skipaclchk, cr) == 0) {
                                /*
                                 * Remove setuid/setgid for non-privileged users
                                 */
                                secpolicy_setid_clear(vap, vp, cr);
                                trim_mask = (mask & (AT_UID|AT_GID));
                        } else {
                                need_policy =  TRUE;
                        }
                } else {
                        need_policy =  TRUE;
                }
        }

        mutex_enter(&zp->z_lock);
        oldva.va_mode = pzp->zp_mode;
        zfs_fuid_map_ids(zp, cr, &oldva.va_uid, &oldva.va_gid);
        if (mask & AT_XVATTR) {
                /*
                 * Update xvattr mask to include only those attributes
                 * that are actually changing.
                 *
                 * the bits will be restored prior to actually setting
                 * the attributes so the caller thinks they were set.
                 */
                if (XVA_ISSET_REQ(xvap, XAT_APPENDONLY)) {
                        if (xoap->xoa_appendonly !=
                            ((pzp->zp_flags & ZFS_APPENDONLY) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_APPENDONLY);
                                XVA_SET_REQ(&tmpxvattr, XAT_APPENDONLY);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_NOUNLINK)) {
                        if (xoap->xoa_nounlink !=
                            ((pzp->zp_flags & ZFS_NOUNLINK) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_NOUNLINK);
                                XVA_SET_REQ(&tmpxvattr, XAT_NOUNLINK);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_IMMUTABLE)) {
                        if (xoap->xoa_immutable !=
                            ((pzp->zp_flags & ZFS_IMMUTABLE) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_IMMUTABLE);
                                XVA_SET_REQ(&tmpxvattr, XAT_IMMUTABLE);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_NODUMP)) {
                        if (xoap->xoa_nodump !=
                            ((pzp->zp_flags & ZFS_NODUMP) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_NODUMP);
                                XVA_SET_REQ(&tmpxvattr, XAT_NODUMP);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_AV_MODIFIED)) {
                        if (xoap->xoa_av_modified !=
                            ((pzp->zp_flags & ZFS_AV_MODIFIED) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_AV_MODIFIED);
                                XVA_SET_REQ(&tmpxvattr, XAT_AV_MODIFIED);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_AV_QUARANTINED)) {
                        if ((vp->v_type != VREG &&
                            xoap->xoa_av_quarantined) ||
                            xoap->xoa_av_quarantined !=
                            ((pzp->zp_flags & ZFS_AV_QUARANTINED) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_AV_QUARANTINED);
                                XVA_SET_REQ(&tmpxvattr, XAT_AV_QUARANTINED);
                        }
                }

                if (need_policy == FALSE &&
                    (XVA_ISSET_REQ(xvap, XAT_AV_SCANSTAMP) ||
                    XVA_ISSET_REQ(xvap, XAT_OPAQUE))) {
                        need_policy = TRUE;
                }
        }

        mutex_exit(&zp->z_lock);

        if (mask & AT_MODE) {
                if (zfs_zaccess(zp, ACE_WRITE_ACL, 0, skipaclchk, cr) == 0) {
                        err = secpolicy_setid_setsticky_clear(vp, vap,
                            &oldva, cr);
                        if (err) {
                                ZFS_EXIT(zfsvfs);
                                return (err);
                        }
                        trim_mask |= AT_MODE;
                } else {
                        need_policy = TRUE;
                }
        }

        if (need_policy) {
                /*
                 * If trim_mask is set then take ownership
                 * has been granted or write_acl is present and user
                 * has the ability to modify mode.  In that case remove
                 * UID|GID and or MODE from mask so that
                 * secpolicy_vnode_setattr() doesn't revoke it.
                 */

                if (trim_mask) {
                        saved_mask = vap->va_mask;
                        vap->va_mask &= ~trim_mask;
                        if (trim_mask & AT_MODE) {
                                /*
                                 * Save the mode, as secpolicy_vnode_setattr()
                                 * will overwrite it with ova.va_mode.
                                 */
                                saved_mode = vap->va_mode;
                        }
                }
                err = secpolicy_vnode_setattr(cr, vp, vap, &oldva, flags,
                    (int (*)(void *, int, cred_t *))zfs_zaccess_unix, zp);
                if (err) {
                        ZFS_EXIT(zfsvfs);
                        return (err);
                }

                if (trim_mask) {
                        vap->va_mask |= saved_mask;
                        if (trim_mask & AT_MODE) {
                                /*
                                 * Recover the mode after
                                 * secpolicy_vnode_setattr().
                                 */
                                vap->va_mode = saved_mode;
                        }
                }
        }

        /*
         * secpolicy_vnode_setattr, or take ownership may have
         * changed va_mask
         */
        mask = vap->va_mask;

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_bonus(tx, zp->z_id);

        if (mask & AT_MODE) {
                uint64_t pmode = pzp->zp_mode;

                new_mode = (pmode & S_IFMT) | (vap->va_mode & ~S_IFMT);

                if (err = zfs_acl_chmod_setattr(zp, &aclp, new_mode))
                        goto out;
                if (pzp->zp_acl.z_acl_extern_obj) {
                        /* Are we upgrading ACL from old V0 format to new V1 */
                        if (zfsvfs->z_version <= ZPL_VERSION_FUID &&
                            pzp->zp_acl.z_acl_version ==
                            ZFS_ACL_VERSION_INITIAL) {
                                dmu_tx_hold_free(tx,
                                    pzp->zp_acl.z_acl_extern_obj, 0,
                                    DMU_OBJECT_END);
                                dmu_tx_hold_write(tx, DMU_NEW_OBJECT,
                                    0, aclp->z_acl_bytes);
                        } else {
                                dmu_tx_hold_write(tx,
                                    pzp->zp_acl.z_acl_extern_obj, 0,
                                    aclp->z_acl_bytes);
                        }
                } else if (aclp->z_acl_bytes > ZFS_ACE_SPACE) {
                        dmu_tx_hold_write(tx, DMU_NEW_OBJECT,
                            0, aclp->z_acl_bytes);
                }
        }

        if (mask & (AT_UID | AT_GID)) {
                if (pzp->zp_xattr) {
                        err = zfs_zget(zp->z_zfsvfs, pzp->zp_xattr, &attrzp);
                        if (err)
                                goto out;
                        dmu_tx_hold_bonus(tx, attrzp->z_id);
                }
                if (mask & AT_UID) {
                        new_uid = zfs_fuid_create(zfsvfs,
                            (uint64_t)vap->va_uid, cr, ZFS_OWNER, &fuidp);
                        if (new_uid != pzp->zp_uid &&
                            zfs_usergroup_overquota(zfsvfs, B_FALSE, new_uid)) {
                                err = EDQUOT;
                                goto out;
                        }
                }

                if (mask & AT_GID) {
                        new_gid = zfs_fuid_create(zfsvfs, (uint64_t)vap->va_gid,
                            cr, ZFS_GROUP, &fuidp);
                        if (new_gid != pzp->zp_gid &&
                            zfs_usergroup_overquota(zfsvfs, B_TRUE, new_gid)) {
                                err = EDQUOT;
                                goto out;
                        }
                }
                fuid_dirtied = zfsvfs->z_fuid_dirty;
                if (fuid_dirtied) {
                        if (zfsvfs->z_fuid_obj == 0) {
                                dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT);
                                dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0,
                                    FUID_SIZE_ESTIMATE(zfsvfs));
                                dmu_tx_hold_zap(tx, MASTER_NODE_OBJ,
                                    FALSE, NULL);
                        } else {
                                dmu_tx_hold_bonus(tx, zfsvfs->z_fuid_obj);
                                dmu_tx_hold_write(tx, zfsvfs->z_fuid_obj, 0,
                                    FUID_SIZE_ESTIMATE(zfsvfs));
                        }
                }
        }

        err = dmu_tx_assign(tx, TXG_NOWAIT);
        if (err) {
                if (err == ERESTART)
                        dmu_tx_wait(tx);
                goto out;
        }

        dmu_buf_will_dirty(zp->z_dbuf, tx);

        /*
         * Set each attribute requested.
         * We group settings according to the locks they need to acquire.
         *
         * Note: you cannot set ctime directly, although it will be
         * updated as a side-effect of calling this function.
         */

        mutex_enter(&zp->z_lock);

        if (mask & AT_MODE) {
                mutex_enter(&zp->z_acl_lock);
                zp->z_phys->zp_mode = new_mode;
                err = zfs_aclset_common(zp, aclp, cr, tx);
                ASSERT3U(err, ==, 0);
                zp->z_acl_cached = aclp;
                aclp = NULL;
                mutex_exit(&zp->z_acl_lock);
        }

        if (attrzp)
                mutex_enter(&attrzp->z_lock);

        if (mask & AT_UID) {
                pzp->zp_uid = new_uid;
                if (attrzp)
                        attrzp->z_phys->zp_uid = new_uid;
        }

        if (mask & AT_GID) {
                pzp->zp_gid = new_gid;
                if (attrzp)
                        attrzp->z_phys->zp_gid = new_gid;
        }

        if (attrzp)
                mutex_exit(&attrzp->z_lock);

        if (mask & AT_ATIME)
                ZFS_TIME_ENCODE(&vap->va_atime, pzp->zp_atime);

        if (mask & AT_MTIME)
                ZFS_TIME_ENCODE(&vap->va_mtime, pzp->zp_mtime);

        /* XXX - shouldn't this be done *before* the ATIME/MTIME checks? */
        if (mask & AT_SIZE)
                zfs_time_stamper_locked(zp, CONTENT_MODIFIED, tx);
        else if (mask != 0)
                zfs_time_stamper_locked(zp, STATE_CHANGED, tx);
        /*
         * Do this after setting timestamps to prevent timestamp
         * update from toggling bit
         */

        if (xoap && (mask & AT_XVATTR)) {

                /*
                 * restore trimmed off masks
                 * so that return masks can be set for caller.
                 */

                if (XVA_ISSET_REQ(&tmpxvattr, XAT_APPENDONLY)) {
                        XVA_SET_REQ(xvap, XAT_APPENDONLY);
                }
                if (XVA_ISSET_REQ(&tmpxvattr, XAT_NOUNLINK)) {
                        XVA_SET_REQ(xvap, XAT_NOUNLINK);
                }
                if (XVA_ISSET_REQ(&tmpxvattr, XAT_IMMUTABLE)) {
                        XVA_SET_REQ(xvap, XAT_IMMUTABLE);
                }
                if (XVA_ISSET_REQ(&tmpxvattr, XAT_NODUMP)) {
                        XVA_SET_REQ(xvap, XAT_NODUMP);
                }
                if (XVA_ISSET_REQ(&tmpxvattr, XAT_AV_MODIFIED)) {
                        XVA_SET_REQ(xvap, XAT_AV_MODIFIED);
                }
                if (XVA_ISSET_REQ(&tmpxvattr, XAT_AV_QUARANTINED)) {
                        XVA_SET_REQ(xvap, XAT_AV_QUARANTINED);
                }

                if (XVA_ISSET_REQ(xvap, XAT_AV_SCANSTAMP)) {
                        size_t len;
                        dmu_object_info_t doi;

                        ASSERT(vp->v_type == VREG);

                        /* Grow the bonus buffer if necessary. */
                        dmu_object_info_from_db(zp->z_dbuf, &doi);
                        len = sizeof (xoap->xoa_av_scanstamp) +
                            sizeof (znode_phys_t);
                        if (len > doi.doi_bonus_size)
                                VERIFY(dmu_set_bonus(zp->z_dbuf, len, tx) == 0);
                }
                zfs_xvattr_set(zp, xvap);
        }

        if (fuid_dirtied)
                zfs_fuid_sync(zfsvfs, tx);

        if (mask != 0)
                zfs_log_setattr(zilog, tx, TX_SETATTR, zp, vap, mask, fuidp);

        mutex_exit(&zp->z_lock);

out:
        if (attrzp)
                VN_RELE(ZTOV(attrzp));

        if (aclp)
                zfs_acl_free(aclp);

        if (fuidp) {
                zfs_fuid_info_free(fuidp);
                fuidp = NULL;
        }

        if (err)
                dmu_tx_abort(tx);
        else
                dmu_tx_commit(tx);

        if (err == ERESTART)
                goto top;

        ZFS_EXIT(zfsvfs);
        return (err);
}

typedef struct zfs_zlock {
        krwlock_t       *zl_rwlock;     /* lock we acquired */
        znode_t         *zl_znode;      /* znode we held */
        struct zfs_zlock *zl_next;      /* next in list */
} zfs_zlock_t;

/*
 * Drop locks and release vnodes that were held by zfs_rename_lock().
 */
static void
zfs_rename_unlock(zfs_zlock_t **zlpp)
{
        zfs_zlock_t *zl;

        while ((zl = *zlpp) != NULL) {
                if (zl->zl_znode != NULL)
                        VN_RELE(ZTOV(zl->zl_znode));
                rw_exit(zl->zl_rwlock);
                *zlpp = zl->zl_next;
                kmem_free(zl, sizeof (*zl));
        }
}

/*
 * Search back through the directory tree, using the ".." entries.
 * Lock each directory in the chain to prevent concurrent renames.
 * Fail any attempt to move a directory into one of its own descendants.
 * XXX - z_parent_lock can overlap with map or grow locks
 */
static int
zfs_rename_lock(znode_t *szp, znode_t *tdzp, znode_t *sdzp, zfs_zlock_t **zlpp)
{
        zfs_zlock_t     *zl;
        znode_t         *zp = tdzp;
        uint64_t        rootid = zp->z_zfsvfs->z_root;
        uint64_t        *oidp = &zp->z_id;
        krwlock_t       *rwlp = &szp->z_parent_lock;
        krw_t           rw = RW_WRITER;

        /*
         * First pass write-locks szp and compares to zp->z_id.
         * Later passes read-lock zp and compare to zp->z_parent.
         */
        do {
                if (!rw_tryenter(rwlp, rw)) {
                        /*
                         * Another thread is renaming in this path.
                         * Note that if we are a WRITER, we don't have any
                         * parent_locks held yet.
                         */
                        if (rw == RW_READER && zp->z_id > szp->z_id) {
                                /*
                                 * Drop our locks and restart
                                 */
                                zfs_rename_unlock(&zl);
                                *zlpp = NULL;
                                zp = tdzp;
                                oidp = &zp->z_id;
                                rwlp = &szp->z_parent_lock;
                                rw = RW_WRITER;
                                continue;
                        } else {
                                /*
                                 * Wait for other thread to drop its locks
                                 */
                                rw_enter(rwlp, rw);
                        }
                }

                zl = kmem_alloc(sizeof (*zl), KM_SLEEP);
                zl->zl_rwlock = rwlp;
                zl->zl_znode = NULL;
                zl->zl_next = *zlpp;
                *zlpp = zl;

                if (*oidp == szp->z_id)         /* We're a descendant of szp */
                        return (EINVAL);

                if (*oidp == rootid)            /* We've hit the top */
                        return (0);

                if (rw == RW_READER) {          /* i.e. not the first pass */
                        int error = zfs_zget(zp->z_zfsvfs, *oidp, &zp);
                        if (error)
                                return (error);
                        zl->zl_znode = zp;
                }
                oidp = &zp->z_phys->zp_parent;
                rwlp = &zp->z_parent_lock;
                rw = RW_READER;

        } while (zp->z_id != sdzp->z_id);

        return (0);
}

/*
 * Move an entry from the provided source directory to the target
 * directory.  Change the entry name as indicated.
 *
 *      IN:     sdvp    - Source directory containing the "old entry".
 *              snm     - Old entry name.
 *              tdvp    - Target directory to contain the "new entry".
 *              tnm     - New entry name.
 *              cr      - credentials of caller.
 *              ct      - caller context
 *              flags   - case flags
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      sdvp,tdvp - ctime|mtime updated
 */
/*ARGSUSED*/
static int
zfs_rename(vnode_t *sdvp, char *snm, vnode_t *tdvp, char *tnm, cred_t *cr,
    caller_context_t *ct, int flags)
{
        znode_t         *tdzp, *szp, *tzp;
        znode_t         *sdzp = VTOZ(sdvp);
        zfsvfs_t        *zfsvfs = sdzp->z_zfsvfs;
        zilog_t         *zilog;
        vnode_t         *realvp;
        zfs_dirlock_t   *sdl, *tdl;
        dmu_tx_t        *tx;
        zfs_zlock_t     *zl;
        int             cmp, serr, terr;
        int             error = 0;
        int             zflg = 0;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(sdzp);
        zilog = zfsvfs->z_log;

        /*
         * Make sure we have the real vp for the target directory.
         */
        if (VOP_REALVP(tdvp, &realvp, ct) == 0)
                tdvp = realvp;

        if (tdvp->v_vfsp != sdvp->v_vfsp || zfsctl_is_node(tdvp)) {
                ZFS_EXIT(zfsvfs);
                return (EXDEV);
        }

        tdzp = VTOZ(tdvp);
        ZFS_VERIFY_ZP(tdzp);
        if (zfsvfs->z_utf8 && u8_validate(tnm,
            strlen(tnm), NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                ZFS_EXIT(zfsvfs);
                return (EILSEQ);
        }

        if (flags & FIGNORECASE)
                zflg |= ZCILOOK;

top:
        szp = NULL;
        tzp = NULL;
        zl = NULL;

        /*
         * This is to prevent the creation of links into attribute space
         * by renaming a linked file into/outof an attribute directory.
         * See the comment in zfs_link() for why this is considered bad.
         */
        if ((tdzp->z_phys->zp_flags & ZFS_XATTR) !=
            (sdzp->z_phys->zp_flags & ZFS_XATTR)) {
                ZFS_EXIT(zfsvfs);
                return (EINVAL);
        }

        /*
         * Lock source and target directory entries.  To prevent deadlock,
         * a lock ordering must be defined.  We lock the directory with
         * the smallest object id first, or if it's a tie, the one with
         * the lexically first name.
         */
        if (sdzp->z_id < tdzp->z_id) {
                cmp = -1;
        } else if (sdzp->z_id > tdzp->z_id) {
                cmp = 1;
        } else {
                /*
                 * First compare the two name arguments without
                 * considering any case folding.
                 */
                int nofold = (zfsvfs->z_norm & ~U8_TEXTPREP_TOUPPER);

                cmp = u8_strcmp(snm, tnm, 0, nofold, U8_UNICODE_LATEST, &error);
                ASSERT(error == 0 || !zfsvfs->z_utf8);
                if (cmp == 0) {
                        /*
                         * POSIX: "If the old argument and the new argument
                         * both refer to links to the same existing file,
                         * the rename() function shall return successfully
                         * and perform no other action."
                         */
                        ZFS_EXIT(zfsvfs);
                        return (0);
                }
                /*
                 * If the file system is case-folding, then we may
                 * have some more checking to do.  A case-folding file
                 * system is either supporting mixed case sensitivity
                 * access or is completely case-insensitive.  Note
                 * that the file system is always case preserving.
                 *
                 * In mixed sensitivity mode case sensitive behavior
                 * is the default.  FIGNORECASE must be used to
                 * explicitly request case insensitive behavior.
                 *
                 * If the source and target names provided differ only
                 * by case (e.g., a request to rename 'tim' to 'Tim'),
                 * we will treat this as a special case in the
                 * case-insensitive mode: as long as the source name
                 * is an exact match, we will allow this to proceed as
                 * a name-change request.
                 */
                if ((zfsvfs->z_case == ZFS_CASE_INSENSITIVE ||
                    (zfsvfs->z_case == ZFS_CASE_MIXED &&
                    flags & FIGNORECASE)) &&
                    u8_strcmp(snm, tnm, 0, zfsvfs->z_norm, U8_UNICODE_LATEST,
                    &error) == 0) {
                        /*
                         * case preserving rename request, require exact
                         * name matches
                         */
                        zflg |= ZCIEXACT;
                        zflg &= ~ZCILOOK;
                }
        }

        /*
         * If the source and destination directories are the same, we should
         * grab the z_name_lock of that directory only once.
         */
        if (sdzp == tdzp) {
                zflg |= ZHAVELOCK;
                rw_enter(&sdzp->z_name_lock, RW_READER);
        }

        if (cmp < 0) {
                serr = zfs_dirent_lock(&sdl, sdzp, snm, &szp,
                    ZEXISTS | zflg, NULL, NULL);
                terr = zfs_dirent_lock(&tdl,
                    tdzp, tnm, &tzp, ZRENAMING | zflg, NULL, NULL);
        } else {
                terr = zfs_dirent_lock(&tdl,
                    tdzp, tnm, &tzp, zflg, NULL, NULL);
                serr = zfs_dirent_lock(&sdl,
                    sdzp, snm, &szp, ZEXISTS | ZRENAMING | zflg,
                    NULL, NULL);
        }

        if (serr) {
                /*
                 * Source entry invalid or not there.
                 */
                if (!terr) {
                        zfs_dirent_unlock(tdl);
                        if (tzp)
                                VN_RELE(ZTOV(tzp));
                }

                if (sdzp == tdzp)
                        rw_exit(&sdzp->z_name_lock);

                if (strcmp(snm, ".") == 0 || strcmp(snm, "..") == 0)
                        serr = EINVAL;
                ZFS_EXIT(zfsvfs);
                return (serr);
        }
        if (terr) {
                zfs_dirent_unlock(sdl);
                VN_RELE(ZTOV(szp));

                if (sdzp == tdzp)
                        rw_exit(&sdzp->z_name_lock);

                if (strcmp(tnm, "..") == 0)
                        terr = EINVAL;
                ZFS_EXIT(zfsvfs);
                return (terr);
        }

        /*
         * Must have write access at the source to remove the old entry
         * and write access at the target to create the new entry.
         * Note that if target and source are the same, this can be
         * done in a single check.
         */

        if (error = zfs_zaccess_rename(sdzp, szp, tdzp, tzp, cr))
                goto out;

        if (ZTOV(szp)->v_type == VDIR) {
                /*
                 * Check to make sure rename is valid.
                 * Can't do a move like this: /usr/a/b to /usr/a/b/c/d
                 */
                if (error = zfs_rename_lock(szp, tdzp, sdzp, &zl))
                        goto out;
        }

        /*
         * Does target exist?
         */
        if (tzp) {
                /*
                 * Source and target must be the same type.
                 */
                if (ZTOV(szp)->v_type == VDIR) {
                        if (ZTOV(tzp)->v_type != VDIR) {
                                error = ENOTDIR;
                                goto out;
                        }
                } else {
                        if (ZTOV(tzp)->v_type == VDIR) {
                                error = EISDIR;
                                goto out;
                        }
                }
                /*
                 * POSIX dictates that when the source and target
                 * entries refer to the same file object, rename
                 * must do nothing and exit without error.
                 */
                if (szp->z_id == tzp->z_id) {
                        error = 0;
                        goto out;
                }
        }

        vnevent_rename_src(ZTOV(szp), sdvp, snm, ct);
        if (tzp)
                vnevent_rename_dest(ZTOV(tzp), tdvp, tnm, ct);

        /*
         * notify the target directory if it is not the same
         * as source directory.
         */
        if (tdvp != sdvp) {
                vnevent_rename_dest_dir(tdvp, ct);
        }

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_bonus(tx, szp->z_id);       /* nlink changes */
        dmu_tx_hold_bonus(tx, sdzp->z_id);      /* nlink changes */
        dmu_tx_hold_zap(tx, sdzp->z_id, FALSE, snm);
        dmu_tx_hold_zap(tx, tdzp->z_id, TRUE, tnm);
        if (sdzp != tdzp)
                dmu_tx_hold_bonus(tx, tdzp->z_id);      /* nlink changes */
        if (tzp)
                dmu_tx_hold_bonus(tx, tzp->z_id);       /* parent changes */
        dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
        error = dmu_tx_assign(tx, TXG_NOWAIT);
        if (error) {
                if (zl != NULL)
                        zfs_rename_unlock(&zl);
                zfs_dirent_unlock(sdl);
                zfs_dirent_unlock(tdl);

                if (sdzp == tdzp)
                        rw_exit(&sdzp->z_name_lock);

                VN_RELE(ZTOV(szp));
                if (tzp)
                        VN_RELE(ZTOV(tzp));
                if (error == ERESTART) {
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto top;
                }
                dmu_tx_abort(tx);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        if (tzp)        /* Attempt to remove the existing target */
                error = zfs_link_destroy(tdl, tzp, tx, zflg, NULL);

        if (error == 0) {
                error = zfs_link_create(tdl, szp, tx, ZRENAMING);
                if (error == 0) {
                        szp->z_phys->zp_flags |= ZFS_AV_MODIFIED;

                        error = zfs_link_destroy(sdl, szp, tx, ZRENAMING, NULL);
                        ASSERT(error == 0);

                        zfs_log_rename(zilog, tx,
                            TX_RENAME | (flags & FIGNORECASE ? TX_CI : 0),
                            sdzp, sdl->dl_name, tdzp, tdl->dl_name, szp);

                        /* Update path information for the target vnode */
                        vn_renamepath(tdvp, ZTOV(szp), tnm, strlen(tnm));
                }
#ifdef FREEBSD_NAMECACHE
                if (error == 0) {
                        cache_purge(sdvp);
                        cache_purge(tdvp);
                }
#endif
        }

        dmu_tx_commit(tx);
out:
        if (zl != NULL)
                zfs_rename_unlock(&zl);

        zfs_dirent_unlock(sdl);
        zfs_dirent_unlock(tdl);

        if (sdzp == tdzp)
                rw_exit(&sdzp->z_name_lock);

        VN_RELE(ZTOV(szp));
        if (tzp)
                VN_RELE(ZTOV(tzp));

        ZFS_EXIT(zfsvfs);

        return (error);
}

/*
 * Insert the indicated symbolic reference entry into the directory.
 *
 *      IN:     dvp     - Directory to contain new symbolic link.
 *              link    - Name for new symlink entry.
 *              vap     - Attributes of new entry.
 *              target  - Target path of new symlink.
 *              cr      - credentials of caller.
 *              ct      - caller context
 *              flags   - case flags
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      dvp - ctime|mtime updated
 */
/*ARGSUSED*/
static int
zfs_symlink(vnode_t *dvp, vnode_t **vpp, char *name, vattr_t *vap, char *link,
    cred_t *cr, kthread_t *td)
{
        znode_t         *zp, *dzp = VTOZ(dvp);
        zfs_dirlock_t   *dl;
        dmu_tx_t        *tx;
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        zilog_t         *zilog;
        int             len = strlen(link);
        int             error;
        int             zflg = ZNEW;
        zfs_acl_ids_t   acl_ids;
        boolean_t       fuid_dirtied;
        int             flags = 0;

        ASSERT(vap->va_type == VLNK);

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(dzp);
        zilog = zfsvfs->z_log;

        if (zfsvfs->z_utf8 && u8_validate(name, strlen(name),
            NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                ZFS_EXIT(zfsvfs);
                return (EILSEQ);
        }
        if (flags & FIGNORECASE)
                zflg |= ZCILOOK;
top:
        if (error = zfs_zaccess(dzp, ACE_ADD_FILE, 0, B_FALSE, cr)) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        if (len > MAXPATHLEN) {
                ZFS_EXIT(zfsvfs);
                return (ENAMETOOLONG);
        }

        /*
         * Attempt to lock directory; fail if entry already exists.
         */
        error = zfs_dirent_lock(&dl, dzp, name, &zp, zflg, NULL, NULL);
        if (error) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        VERIFY(0 == zfs_acl_ids_create(dzp, 0, vap, cr, NULL, &acl_ids));
        if (zfs_acl_ids_overquota(zfsvfs, &acl_ids)) {
                zfs_acl_ids_free(&acl_ids);
                zfs_dirent_unlock(dl);
                ZFS_EXIT(zfsvfs);
                return (EDQUOT);
        }
        tx = dmu_tx_create(zfsvfs->z_os);
        fuid_dirtied = zfsvfs->z_fuid_dirty;
        dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0, MAX(1, len));
        dmu_tx_hold_bonus(tx, dzp->z_id);
        dmu_tx_hold_zap(tx, dzp->z_id, TRUE, name);
        if (acl_ids.z_aclp->z_acl_bytes > ZFS_ACE_SPACE)
                dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0, SPA_MAXBLOCKSIZE);
        if (fuid_dirtied)
                zfs_fuid_txhold(zfsvfs, tx);
        error = dmu_tx_assign(tx, TXG_NOWAIT);
        if (error) {
                zfs_acl_ids_free(&acl_ids);
                zfs_dirent_unlock(dl);
                if (error == ERESTART) {
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto top;
                }
                dmu_tx_abort(tx);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        dmu_buf_will_dirty(dzp->z_dbuf, tx);

        /*
         * Create a new object for the symlink.
         * Put the link content into bonus buffer if it will fit;
         * otherwise, store it just like any other file data.
         */
        if (sizeof (znode_phys_t) + len <= dmu_bonus_max()) {
                zfs_mknode(dzp, vap, tx, cr, 0, &zp, len, &acl_ids);
                if (len != 0)
                        bcopy(link, zp->z_phys + 1, len);
        } else {
                dmu_buf_t *dbp;

                zfs_mknode(dzp, vap, tx, cr, 0, &zp, 0, &acl_ids);

                if (fuid_dirtied)
                        zfs_fuid_sync(zfsvfs, tx);
                /*
                 * Nothing can access the znode yet so no locking needed
                 * for growing the znode's blocksize.
                 */
                zfs_grow_blocksize(zp, len, tx);

                VERIFY(0 == dmu_buf_hold(zfsvfs->z_os,
                    zp->z_id, 0, FTAG, &dbp));
                dmu_buf_will_dirty(dbp, tx);

                ASSERT3U(len, <=, dbp->db_size);
                bcopy(link, dbp->db_data, len);
                dmu_buf_rele(dbp, FTAG);
        }
        zp->z_phys->zp_size = len;

        /*
         * Insert the new object into the directory.
         */
        (void) zfs_link_create(dl, zp, tx, ZNEW);
        if (error == 0) {
                uint64_t txtype = TX_SYMLINK;
                if (flags & FIGNORECASE)
                        txtype |= TX_CI;
                zfs_log_symlink(zilog, tx, txtype, dzp, zp, name, link);
                *vpp = ZTOV(zp);
        }

        zfs_acl_ids_free(&acl_ids);

        dmu_tx_commit(tx);

        zfs_dirent_unlock(dl);

        ZFS_EXIT(zfsvfs);
        return (error);
}

/*
 * Return, in the buffer contained in the provided uio structure,
 * the symbolic path referred to by vp.
 *
 *      IN:     vp      - vnode of symbolic link.
 *              uoip    - structure to contain the link path.
 *              cr      - credentials of caller.
 *              ct      - caller context
 *
 *      OUT:    uio     - structure to contain the link path.
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      vp - atime updated
 */
/* ARGSUSED */
static int
zfs_readlink(vnode_t *vp, uio_t *uio, cred_t *cr, caller_context_t *ct)
{
        znode_t         *zp = VTOZ(vp);
        zfsvfs_t        *zfsvfs = zp->z_zfsvfs;
        size_t          bufsz;
        int             error;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        bufsz = (size_t)zp->z_phys->zp_size;
        if (bufsz + sizeof (znode_phys_t) <= zp->z_dbuf->db_size) {
                error = uiomove(zp->z_phys + 1,
                    MIN((size_t)bufsz, uio->uio_resid), UIO_READ, uio);
        } else {
                dmu_buf_t *dbp;
                error = dmu_buf_hold(zfsvfs->z_os, zp->z_id, 0, FTAG, &dbp);
                if (error) {
                        ZFS_EXIT(zfsvfs);
                        return (error);
                }
                error = uiomove(dbp->db_data,
                    MIN((size_t)bufsz, uio->uio_resid), UIO_READ, uio);
                dmu_buf_rele(dbp, FTAG);
        }

        ZFS_ACCESSTIME_STAMP(zfsvfs, zp);
        ZFS_EXIT(zfsvfs);
        return (error);
}

/*
 * Insert a new entry into directory tdvp referencing svp.
 *
 *      IN:     tdvp    - Directory to contain new entry.
 *              svp     - vnode of new entry.
 *              name    - name of new entry.
 *              cr      - credentials of caller.
 *              ct      - caller context
 *
 *      RETURN: 0 if success
 *              error code if failure
 *
 * Timestamps:
 *      tdvp - ctime|mtime updated
 *       svp - ctime updated
 */
/* ARGSUSED */
static int
zfs_link(vnode_t *tdvp, vnode_t *svp, char *name, cred_t *cr,
    caller_context_t *ct, int flags)
{
        znode_t         *dzp = VTOZ(tdvp);
        znode_t         *tzp, *szp;
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        zilog_t         *zilog;
        zfs_dirlock_t   *dl;
        dmu_tx_t        *tx;
        vnode_t         *realvp;
        int             error;
        int             zf = ZNEW;
        uint64_t        parent;
        uid_t           owner;

        ASSERT(tdvp->v_type == VDIR);

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(dzp);
        zilog = zfsvfs->z_log;

        if (VOP_REALVP(svp, &realvp, ct) == 0)
                svp = realvp;

        /*
         * POSIX dictates that we return EPERM here.
         * Better choices include ENOTSUP or EISDIR.
         */
        if (svp->v_type == VDIR) {
                ZFS_EXIT(zfsvfs);
                return (EPERM);
        }

        if (svp->v_vfsp != tdvp->v_vfsp || zfsctl_is_node(svp)) {
                ZFS_EXIT(zfsvfs);
                return (EXDEV);
        }

        szp = VTOZ(svp);
        ZFS_VERIFY_ZP(szp);

        /* Prevent links to .zfs/shares files */

        if (szp->z_phys->zp_parent == zfsvfs->z_shares_dir) {
                ZFS_EXIT(zfsvfs);
                return (EPERM);
        }

        if (zfsvfs->z_utf8 && u8_validate(name,
            strlen(name), NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                ZFS_EXIT(zfsvfs);
                return (EILSEQ);
        }
        if (flags & FIGNORECASE)
                zf |= ZCILOOK;

        /*
         * We do not support links between attributes and non-attributes
         * because of the potential security risk of creating links
         * into "normal" file space in order to circumvent restrictions
         * imposed in attribute space.
         */
        if ((szp->z_phys->zp_flags & ZFS_XATTR) !=
            (dzp->z_phys->zp_flags & ZFS_XATTR)) {
                ZFS_EXIT(zfsvfs);
                return (EINVAL);
        }


        owner = zfs_fuid_map_id(zfsvfs, szp->z_phys->zp_uid, cr, ZFS_OWNER);
        if (owner != crgetuid(cr) &&
            secpolicy_basic_link(svp, cr) != 0) {
                ZFS_EXIT(zfsvfs);
                return (EPERM);
        }

        if (error = zfs_zaccess(dzp, ACE_ADD_FILE, 0, B_FALSE, cr)) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

top:
        /*
         * Attempt to lock directory; fail if entry already exists.
         */
        error = zfs_dirent_lock(&dl, dzp, name, &tzp, zf, NULL, NULL);
        if (error) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_bonus(tx, szp->z_id);
        dmu_tx_hold_zap(tx, dzp->z_id, TRUE, name);
        error = dmu_tx_assign(tx, TXG_NOWAIT);
        if (error) {
                zfs_dirent_unlock(dl);
                if (error == ERESTART) {
                        dmu_tx_wait(tx);
                        dmu_tx_abort(tx);
                        goto top;
                }
                dmu_tx_abort(tx);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        error = zfs_link_create(dl, szp, tx, 0);

        if (error == 0) {
                uint64_t txtype = TX_LINK;
                if (flags & FIGNORECASE)
                        txtype |= TX_CI;
                zfs_log_link(zilog, tx, txtype, dzp, szp, name);
        }

        dmu_tx_commit(tx);

        zfs_dirent_unlock(dl);

        if (error == 0) {
                vnevent_link(svp, ct);
        }

        ZFS_EXIT(zfsvfs);
        return (error);
}

/*ARGSUSED*/
void
zfs_inactive(vnode_t *vp, cred_t *cr, caller_context_t *ct)
{
        znode_t *zp = VTOZ(vp);
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        int error;

        rw_enter(&zfsvfs->z_teardown_inactive_lock, RW_READER);
        if (zp->z_dbuf == NULL) {
                /*
                 * The fs has been unmounted, or we did a
                 * suspend/resume and this file no longer exists.
                 */
                VI_LOCK(vp);
                vp->v_count = 0; /* count arrives as 1 */
                VI_UNLOCK(vp);
                vrecycle(vp, curthread);
                rw_exit(&zfsvfs->z_teardown_inactive_lock);
                return;
        }

        if (zp->z_atime_dirty && zp->z_unlinked == 0) {
                dmu_tx_t *tx = dmu_tx_create(zfsvfs->z_os);

                dmu_tx_hold_bonus(tx, zp->z_id);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        dmu_tx_abort(tx);
                } else {
                        dmu_buf_will_dirty(zp->z_dbuf, tx);
                        mutex_enter(&zp->z_lock);
                        zp->z_atime_dirty = 0;
                        mutex_exit(&zp->z_lock);
                        dmu_tx_commit(tx);
                }
        }

        zfs_zinactive(zp);
        rw_exit(&zfsvfs->z_teardown_inactive_lock);
}

CTASSERT(sizeof(struct zfid_short) <= sizeof(struct fid));
CTASSERT(sizeof(struct zfid_long) <= sizeof(struct fid));

/*ARGSUSED*/
static int
zfs_fid(vnode_t *vp, fid_t *fidp, caller_context_t *ct)
{
        znode_t         *zp = VTOZ(vp);
        zfsvfs_t        *zfsvfs = zp->z_zfsvfs;
        uint32_t        gen;
        uint64_t        object = zp->z_id;
        zfid_short_t    *zfid;
        int             size, i;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);
        gen = (uint32_t)zp->z_gen;

        size = (zfsvfs->z_parent != zfsvfs) ? LONG_FID_LEN : SHORT_FID_LEN;
        fidp->fid_len = size;

        zfid = (zfid_short_t *)fidp;

        zfid->zf_len = size;

        for (i = 0; i < sizeof (zfid->zf_object); i++)
                zfid->zf_object[i] = (uint8_t)(object >> (8 * i));

        /* Must have a non-zero generation number to distinguish from .zfs */
        if (gen == 0)
                gen = 1;
        for (i = 0; i < sizeof (zfid->zf_gen); i++)
                zfid->zf_gen[i] = (uint8_t)(gen >> (8 * i));

        if (size == LONG_FID_LEN) {
                uint64_t        objsetid = dmu_objset_id(zfsvfs->z_os);
                zfid_long_t     *zlfid;

                zlfid = (zfid_long_t *)fidp;

                for (i = 0; i < sizeof (zlfid->zf_setid); i++)
                        zlfid->zf_setid[i] = (uint8_t)(objsetid >> (8 * i));

                /* XXX - this should be the generation number for the objset */
                for (i = 0; i < sizeof (zlfid->zf_setgen); i++)
                        zlfid->zf_setgen[i] = 0;
        }

        ZFS_EXIT(zfsvfs);
        return (0);
}

static int
zfs_pathconf(vnode_t *vp, int cmd, ulong_t *valp, cred_t *cr,
    caller_context_t *ct)
{
        znode_t         *zp, *xzp;
        zfsvfs_t        *zfsvfs;
        zfs_dirlock_t   *dl;
        int             error;

        switch (cmd) {
        case _PC_LINK_MAX:
                *valp = INT_MAX;
                return (0);

        case _PC_FILESIZEBITS:
                *valp = 64;
                return (0);

#if 0
        case _PC_XATTR_EXISTS:
                zp = VTOZ(vp);
                zfsvfs = zp->z_zfsvfs;
                ZFS_ENTER(zfsvfs);
                ZFS_VERIFY_ZP(zp);
                *valp = 0;
                error = zfs_dirent_lock(&dl, zp, "", &xzp,
                    ZXATTR | ZEXISTS | ZSHARED, NULL, NULL);
                if (error == 0) {
                        zfs_dirent_unlock(dl);
                        if (!zfs_dirempty(xzp))
                                *valp = 1;
                        VN_RELE(ZTOV(xzp));
                } else if (error == ENOENT) {
                        /*
                         * If there aren't extended attributes, it's the
                         * same as having zero of them.
                         */
                        error = 0;
                }
                ZFS_EXIT(zfsvfs);
                return (error);
#endif

        case _PC_ACL_EXTENDED:
                *valp = 0;
                return (0);

        case _PC_ACL_NFS4:
                *valp = 1;
                return (0);

        case _PC_ACL_PATH_MAX:
                *valp = ACL_MAX_ENTRIES;
                return (0);

        case _PC_MIN_HOLE_SIZE:
                *valp = (int)SPA_MINBLOCKSIZE;
                return (0);

        default:
                return (EOPNOTSUPP);
        }
}

/*ARGSUSED*/
static int
zfs_getsecattr(vnode_t *vp, vsecattr_t *vsecp, int flag, cred_t *cr,
    caller_context_t *ct)
{
        znode_t *zp = VTOZ(vp);
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        int error;
        boolean_t skipaclchk = (flag & ATTR_NOACLCHECK) ? B_TRUE : B_FALSE;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);
        error = zfs_getacl(zp, vsecp, skipaclchk, cr);
        ZFS_EXIT(zfsvfs);

        return (error);
}

/*ARGSUSED*/
static int
zfs_setsecattr(vnode_t *vp, vsecattr_t *vsecp, int flag, cred_t *cr,
    caller_context_t *ct)
{
        znode_t *zp = VTOZ(vp);
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        int error;
        boolean_t skipaclchk = (flag & ATTR_NOACLCHECK) ? B_TRUE : B_FALSE;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);
        error = zfs_setacl(zp, vsecp, skipaclchk, cr);
        ZFS_EXIT(zfsvfs);
        return (error);
}

static int
zfs_freebsd_open(ap)
        struct vop_open_args /* {
                struct vnode *a_vp;
                int a_mode;
                struct ucred *a_cred;
                struct thread *a_td;
        } */ *ap;
{
        vnode_t *vp = ap->a_vp;
        znode_t *zp = VTOZ(vp);
        int error;

        error = zfs_open(&vp, ap->a_mode, ap->a_cred, NULL);
        if (error == 0)
                vnode_create_vobject(vp, zp->z_phys->zp_size, ap->a_td);
        return (error);
}

static int
zfs_freebsd_close(ap)
        struct vop_close_args /* {
                struct vnode *a_vp;
                int  a_fflag;
                struct ucred *a_cred;
                struct thread *a_td;
        } */ *ap;
{

        return (zfs_close(ap->a_vp, ap->a_fflag, 0, 0, ap->a_cred, NULL));
}

static int
zfs_freebsd_ioctl(ap)
        struct vop_ioctl_args /* {
                struct vnode *a_vp;
                u_long a_command;
                caddr_t a_data;
                int a_fflag;
                struct ucred *cred;
                struct thread *td;
        } */ *ap;
{

        return (zfs_ioctl(ap->a_vp, ap->a_command, (intptr_t)ap->a_data,
            ap->a_fflag, ap->a_cred, NULL, NULL));
}

static int
zfs_freebsd_read(ap)
        struct vop_read_args /* {
                struct vnode *a_vp;
                struct uio *a_uio;
                int a_ioflag;
                struct ucred *a_cred;
        } */ *ap;
{

        return (zfs_read(ap->a_vp, ap->a_uio, ap->a_ioflag, ap->a_cred, NULL));
}

static int
zfs_freebsd_write(ap)
        struct vop_write_args /* {
                struct vnode *a_vp;
                struct uio *a_uio;
                int a_ioflag;
                struct ucred *a_cred;
        } */ *ap;
{

        return (zfs_write(ap->a_vp, ap->a_uio, ap->a_ioflag, ap->a_cred, NULL));
}

static int
zfs_freebsd_access(ap)
        struct vop_access_args /* {
                struct vnode *a_vp;
                accmode_t a_accmode;
                struct ucred *a_cred;
                struct thread *a_td;
        } */ *ap;
{
        accmode_t accmode;
        int error = 0;

        /*
         * ZFS itself only knowns about VREAD, VWRITE, VEXEC and VAPPEND,
         */
        accmode = ap->a_accmode & (VREAD|VWRITE|VEXEC|VAPPEND);
        if (accmode != 0)
                error = zfs_access(ap->a_vp, accmode, 0, ap->a_cred, NULL);

        /*
         * VADMIN has to be handled by vaccess().
         */
        if (error == 0) {
                accmode = ap->a_accmode & ~(VREAD|VWRITE|VEXEC|VAPPEND);
                if (accmode != 0) {
                        vnode_t *vp = ap->a_vp;
                        znode_t *zp = VTOZ(vp);
                        znode_phys_t *zphys = zp->z_phys;

                        error = vaccess(vp->v_type, zphys->zp_mode,
                            zphys->zp_uid, zphys->zp_gid, accmode, ap->a_cred,
                            NULL);
                }
        }

        return (error);
}

static int
zfs_freebsd_lookup(ap)
        struct vop_lookup_args /* {
                struct vnode *a_dvp;
                struct vnode **a_vpp;
                struct componentname *a_cnp;
        } */ *ap;
{
        struct componentname *cnp = ap->a_cnp;
        char nm[NAME_MAX + 1];

        ASSERT(cnp->cn_namelen < sizeof(nm));
        strlcpy(nm, cnp->cn_nameptr, MIN(cnp->cn_namelen + 1, sizeof(nm)));

        return (zfs_lookup(ap->a_dvp, nm, ap->a_vpp, cnp, cnp->cn_nameiop,
            cnp->cn_cred, cnp->cn_thread, 0));
}

static int
zfs_freebsd_create(ap)
        struct vop_create_args /* {
                struct vnode *a_dvp;
                struct vnode **a_vpp;
                struct componentname *a_cnp;
                struct vattr *a_vap;
        } */ *ap;
{
        struct componentname *cnp = ap->a_cnp;
        vattr_t *vap = ap->a_vap;
        int mode;

        ASSERT(cnp->cn_flags & SAVENAME);

        vattr_init_mask(vap);
        mode = vap->va_mode & ALLPERMS;

        return (zfs_create(ap->a_dvp, cnp->cn_nameptr, vap, !EXCL, mode,
            ap->a_vpp, cnp->cn_cred, cnp->cn_thread));
}

static int
zfs_freebsd_remove(ap)
        struct vop_remove_args /* {
                struct vnode *a_dvp;
                struct vnode *a_vp;
                struct componentname *a_cnp;
        } */ *ap;
{

        ASSERT(ap->a_cnp->cn_flags & SAVENAME);

        return (zfs_remove(ap->a_dvp, ap->a_cnp->cn_nameptr,
            ap->a_cnp->cn_cred, NULL, 0));
}

static int
zfs_freebsd_mkdir(ap)
        struct vop_mkdir_args /* {
                struct vnode *a_dvp;
                struct vnode **a_vpp;
                struct componentname *a_cnp;
                struct vattr *a_vap;
        } */ *ap;
{
        vattr_t *vap = ap->a_vap;

        ASSERT(ap->a_cnp->cn_flags & SAVENAME);

        vattr_init_mask(vap);

        return (zfs_mkdir(ap->a_dvp, ap->a_cnp->cn_nameptr, vap, ap->a_vpp,
            ap->a_cnp->cn_cred, NULL, 0, NULL));
}

static int
zfs_freebsd_rmdir(ap)
        struct vop_rmdir_args /* {
                struct vnode *a_dvp;
                struct vnode *a_vp;
                struct componentname *a_cnp;
        } */ *ap;
{
        struct componentname *cnp = ap->a_cnp;

        ASSERT(cnp->cn_flags & SAVENAME);

        return (zfs_rmdir(ap->a_dvp, cnp->cn_nameptr, NULL, cnp->cn_cred, NULL, 0));
}

static int
zfs_freebsd_readdir(ap)
        struct vop_readdir_args /* {
                struct vnode *a_vp;
                struct uio *a_uio;
                struct ucred *a_cred;
                int *a_eofflag;
                int *a_ncookies;
                u_long **a_cookies;
        } */ *ap;
{

        return (zfs_readdir(ap->a_vp, ap->a_uio, ap->a_cred, ap->a_eofflag,
            ap->a_ncookies, ap->a_cookies));
}

static int
zfs_freebsd_fsync(ap)
        struct vop_fsync_args /* {
                struct vnode *a_vp;
                int a_waitfor;
                struct thread *a_td;
        } */ *ap;
{

        vop_stdfsync(ap);
        return (zfs_fsync(ap->a_vp, 0, ap->a_td->td_ucred, NULL));
}

static int
zfs_freebsd_getattr(ap)
        struct vop_getattr_args /* {
                struct vnode *a_vp;
                struct vattr *a_vap;
                struct ucred *a_cred;
                struct thread *a_td;
        } */ *ap;
{
        vattr_t *vap = ap->a_vap;
        xvattr_t xvap;
        u_long fflags = 0;
        int error;

        xva_init(&xvap);
        xvap.xva_vattr = *vap;
        xvap.xva_vattr.va_mask |= AT_XVATTR;

        /* Convert chflags into ZFS-type flags. */
        /* XXX: what about SF_SETTABLE?. */
        XVA_SET_REQ(&xvap, XAT_IMMUTABLE);
        XVA_SET_REQ(&xvap, XAT_APPENDONLY);
        XVA_SET_REQ(&xvap, XAT_NOUNLINK);
        XVA_SET_REQ(&xvap, XAT_NODUMP);
        error = zfs_getattr(ap->a_vp, (vattr_t *)&xvap, 0, ap->a_cred, NULL);
        if (error != 0)
                return (error);

        /* Convert ZFS xattr into chflags. */
#define FLAG_CHECK(fflag, xflag, xfield)        do {                    \
        if (XVA_ISSET_RTN(&xvap, (xflag)) && (xfield) != 0)             \
                fflags |= (fflag);                                      \
} while (0)
        FLAG_CHECK(SF_IMMUTABLE, XAT_IMMUTABLE,
            xvap.xva_xoptattrs.xoa_immutable);
        FLAG_CHECK(SF_APPEND, XAT_APPENDONLY,
            xvap.xva_xoptattrs.xoa_appendonly);
        FLAG_CHECK(SF_NOUNLINK, XAT_NOUNLINK,
            xvap.xva_xoptattrs.xoa_nounlink);
        FLAG_CHECK(UF_NODUMP, XAT_NODUMP,
            xvap.xva_xoptattrs.xoa_nodump);
#undef  FLAG_CHECK
        *vap = xvap.xva_vattr;
        vap->va_flags = fflags;
        return (0);
}

static int
zfs_freebsd_setattr(ap)
        struct vop_setattr_args /* {
                struct vnode *a_vp;
                struct vattr *a_vap;
                struct ucred *a_cred;
                struct thread *a_td;
        } */ *ap;
{
        vnode_t *vp = ap->a_vp;
        vattr_t *vap = ap->a_vap;
        cred_t *cred = ap->a_cred;
        xvattr_t xvap;
        u_long fflags;
        uint64_t zflags;

        vattr_init_mask(vap);
        vap->va_mask &= ~AT_NOSET;

        xva_init(&xvap);
        xvap.xva_vattr = *vap;

        zflags = VTOZ(vp)->z_phys->zp_flags;

        if (vap->va_flags != VNOVAL) {
                zfsvfs_t *zfsvfs = VTOZ(vp)->z_zfsvfs;
                int error;

                if (zfsvfs->z_use_fuids == B_FALSE)
                        return (EOPNOTSUPP);

                fflags = vap->va_flags;
                if ((fflags & ~(SF_IMMUTABLE|SF_APPEND|SF_NOUNLINK|UF_NODUMP)) != 0)
                        return (EOPNOTSUPP);
                /*
                 * Unprivileged processes are not permitted to unset system
                 * flags, or modify flags if any system flags are set.
                 * Privileged non-jail processes may not modify system flags
                 * if securelevel > 0 and any existing system flags are set.
                 * Privileged jail processes behave like privileged non-jail
                 * processes if the security.jail.chflags_allowed sysctl is
                 * is non-zero; otherwise, they behave like unprivileged
                 * processes.
                 */
                if (secpolicy_fs_owner(vp->v_mount, cred) == 0 ||
                    priv_check_cred(cred, PRIV_VFS_SYSFLAGS, 0) == 0) {
                        if (zflags &
                            (ZFS_IMMUTABLE | ZFS_APPENDONLY | ZFS_NOUNLINK)) {
                                error = securelevel_gt(cred, 0);
                                if (error != 0)
                                        return (error);
                        }
                } else {
                        /*
                         * Callers may only modify the file flags on objects they
                         * have VADMIN rights for.
                         */
                        if ((error = VOP_ACCESS(vp, VADMIN, cred, curthread)) != 0)
                                return (error);
                        if (zflags &
                            (ZFS_IMMUTABLE | ZFS_APPENDONLY | ZFS_NOUNLINK)) {
                                return (EPERM);
                        }
                        if (fflags &
                            (SF_IMMUTABLE | SF_APPEND | SF_NOUNLINK)) {
                                return (EPERM);
                        }
                }

#define FLAG_CHANGE(fflag, zflag, xflag, xfield)        do {            \
        if (((fflags & (fflag)) && !(zflags & (zflag))) ||              \
            ((zflags & (zflag)) && !(fflags & (fflag)))) {              \
                XVA_SET_REQ(&xvap, (xflag));                            \
                (xfield) = ((fflags & (fflag)) != 0);                   \
        }                                                               \
} while (0)
                /* Convert chflags into ZFS-type flags. */
                /* XXX: what about SF_SETTABLE?. */
                FLAG_CHANGE(SF_IMMUTABLE, ZFS_IMMUTABLE, XAT_IMMUTABLE,
                    xvap.xva_xoptattrs.xoa_immutable);
                FLAG_CHANGE(SF_APPEND, ZFS_APPENDONLY, XAT_APPENDONLY,
                    xvap.xva_xoptattrs.xoa_appendonly);
                FLAG_CHANGE(SF_NOUNLINK, ZFS_NOUNLINK, XAT_NOUNLINK,
                    xvap.xva_xoptattrs.xoa_nounlink);
                FLAG_CHANGE(UF_NODUMP, ZFS_NODUMP, XAT_NODUMP,
                    xvap.xva_xoptattrs.xoa_nodump);
#undef  FLAG_CHANGE
        }
        return (zfs_setattr(vp, (vattr_t *)&xvap, 0, cred, NULL));
}

static int
zfs_freebsd_rename(ap)
        struct vop_rename_args  /* {
                struct vnode *a_fdvp;
                struct vnode *a_fvp;
                struct componentname *a_fcnp;
                struct vnode *a_tdvp;
                struct vnode *a_tvp;
                struct componentname *a_tcnp;
        } */ *ap;
{
        vnode_t *fdvp = ap->a_fdvp;
        vnode_t *fvp = ap->a_fvp;
        vnode_t *tdvp = ap->a_tdvp;
        vnode_t *tvp = ap->a_tvp;
        int error;

        ASSERT(ap->a_fcnp->cn_flags & (SAVENAME|SAVESTART));
        ASSERT(ap->a_tcnp->cn_flags & (SAVENAME|SAVESTART));

        error = zfs_rename(fdvp, ap->a_fcnp->cn_nameptr, tdvp,
            ap->a_tcnp->cn_nameptr, ap->a_fcnp->cn_cred, NULL, 0);

        if (tdvp == tvp)
                VN_RELE(tdvp);
        else
                VN_URELE(tdvp);
        if (tvp)
                VN_URELE(tvp);
        VN_RELE(fdvp);
        VN_RELE(fvp);

        return (error);
}

static int
zfs_freebsd_symlink(ap)
        struct vop_symlink_args /* {
                struct vnode *a_dvp;
                struct vnode **a_vpp;
                struct componentname *a_cnp;
                struct vattr *a_vap;
                char *a_target;
        } */ *ap;
{
        struct componentname *cnp = ap->a_cnp;
        vattr_t *vap = ap->a_vap;

        ASSERT(cnp->cn_flags & SAVENAME);

        vap->va_type = VLNK;    /* FreeBSD: Syscall only sets va_mode. */
        vattr_init_mask(vap);

        return (zfs_symlink(ap->a_dvp, ap->a_vpp, cnp->cn_nameptr, vap,
            ap->a_target, cnp->cn_cred, cnp->cn_thread));
}

static int
zfs_freebsd_readlink(ap)
        struct vop_readlink_args /* {
                struct vnode *a_vp;
                struct uio *a_uio;
                struct ucred *a_cred;
        } */ *ap;
{

        return (zfs_readlink(ap->a_vp, ap->a_uio, ap->a_cred, NULL));
}

static int
zfs_freebsd_link(ap)
        struct vop_link_args /* {
                struct vnode *a_tdvp;
                struct vnode *a_vp;
                struct componentname *a_cnp;
        } */ *ap;
{
        struct componentname *cnp = ap->a_cnp;

        ASSERT(cnp->cn_flags & SAVENAME);

        return (zfs_link(ap->a_tdvp, ap->a_vp, cnp->cn_nameptr, cnp->cn_cred, NULL, 0));
}

static int
zfs_freebsd_inactive(ap)
        struct vop_inactive_args /* {
                struct vnode *a_vp;
                struct thread *a_td;
        } */ *ap;
{
        vnode_t *vp = ap->a_vp;

        zfs_inactive(vp, ap->a_td->td_ucred, NULL);
        return (0);
}

static void
zfs_reclaim_complete(void *arg, int pending)
{
        znode_t *zp = arg;
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;

        rw_enter(&zfsvfs->z_teardown_inactive_lock, RW_READER);
        if (zp->z_dbuf != NULL) {
                ZFS_OBJ_HOLD_ENTER(zfsvfs, zp->z_id);
                zfs_znode_dmu_fini(zp);
                ZFS_OBJ_HOLD_EXIT(zfsvfs, zp->z_id);
        }
        zfs_znode_free(zp);
        rw_exit(&zfsvfs->z_teardown_inactive_lock);
        /*
         * If the file system is being unmounted, there is a process waiting
         * for us, wake it up.
         */
        if (zfsvfs->z_unmounted)
                wakeup_one(zfsvfs);
}

static int
zfs_freebsd_reclaim(ap)
        struct vop_reclaim_args /* {
                struct vnode *a_vp;
                struct thread *a_td;
        } */ *ap;
{
        vnode_t *vp = ap->a_vp;
        znode_t *zp = VTOZ(vp);
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;

        rw_enter(&zfsvfs->z_teardown_inactive_lock, RW_READER);

        ASSERT(zp != NULL);

        /*
         * Destroy the vm object and flush associated pages.
         */
        vnode_destroy_vobject(vp);

        mutex_enter(&zp->z_lock);
        ASSERT(zp->z_phys != NULL);
        zp->z_vnode = NULL;
        mutex_exit(&zp->z_lock);

        if (zp->z_unlinked)
                ;       /* Do nothing. */
        else if (zp->z_dbuf == NULL)
                zfs_znode_free(zp);
        else /* if (!zp->z_unlinked && zp->z_dbuf != NULL) */ {
                int locked;

                locked = MUTEX_HELD(ZFS_OBJ_MUTEX(zfsvfs, zp->z_id)) ? 2 :
                    ZFS_OBJ_HOLD_TRYENTER(zfsvfs, zp->z_id);
                if (locked == 0) {
                        /*
                         * Lock can't be obtained due to deadlock possibility,
                         * so defer znode destruction.
                         */
                        TASK_INIT(&zp->z_task, 0, zfs_reclaim_complete, zp);
                        taskqueue_enqueue(taskqueue_thread, &zp->z_task);
                } else {
                        zfs_znode_dmu_fini(zp);
                        if (locked == 1)
                                ZFS_OBJ_HOLD_EXIT(zfsvfs, zp->z_id);
                        zfs_znode_free(zp);
                }
        }
        VI_LOCK(vp);
        vp->v_data = NULL;
        ASSERT(vp->v_holdcnt >= 1);
        VI_UNLOCK(vp);
        rw_exit(&zfsvfs->z_teardown_inactive_lock);
        return (0);
}

static int
zfs_freebsd_fid(ap)
        struct vop_fid_args /* {
                struct vnode *a_vp;
                struct fid *a_fid;
        } */ *ap;
{

        return (zfs_fid(ap->a_vp, (void *)ap->a_fid, NULL));
}

static int
zfs_freebsd_pathconf(ap)
        struct vop_pathconf_args /* {
                struct vnode *a_vp;
                int a_name;
                register_t *a_retval;
        } */ *ap;
{
        ulong_t val;
        int error;

        error = zfs_pathconf(ap->a_vp, ap->a_name, &val, curthread->td_ucred, NULL);
        if (error == 0)
                *ap->a_retval = val;
        else if (error == EOPNOTSUPP)
                error = vop_stdpathconf(ap);
        return (error);
}

static int
zfs_freebsd_fifo_pathconf(ap)
        struct vop_pathconf_args /* {
                struct vnode *a_vp;
                int a_name;
                register_t *a_retval;
        } */ *ap;
{

        switch (ap->a_name) {
        case _PC_ACL_EXTENDED:
        case _PC_ACL_NFS4:
        case _PC_ACL_PATH_MAX:
        case _PC_MAC_PRESENT:
                return (zfs_freebsd_pathconf(ap));
        default:
                return (fifo_specops.vop_pathconf(ap));
        }
}

/*
 * FreeBSD's extended attributes namespace defines file name prefix for ZFS'
 * extended attribute name:
 *
 *      NAMESPACE       PREFIX  
 *      system          freebsd:system:
 *      user            (none, can be used to access ZFS fsattr(5) attributes
 *                      created on Solaris)
 */
static int
zfs_create_attrname(int attrnamespace, const char *name, char *attrname,
    size_t size)
{
        const char *namespace, *prefix, *suffix;

        /* We don't allow '/' character in attribute name. */
        if (strchr(name, '/') != NULL)
                return (EINVAL);
        /* We don't allow attribute names that start with "freebsd:" string. */
        if (strncmp(name, "freebsd:", 8) == 0)
                return (EINVAL);

        bzero(attrname, size);

        switch (attrnamespace) {
        case EXTATTR_NAMESPACE_USER:
#if 0
                prefix = "freebsd:";
                namespace = EXTATTR_NAMESPACE_USER_STRING;
                suffix = ":";
#else
                /*
                 * This is the default namespace by which we can access all
                 * attributes created on Solaris.
                 */
                prefix = namespace = suffix = "";
#endif
                break;
        case EXTATTR_NAMESPACE_SYSTEM:
                prefix = "freebsd:";
                namespace = EXTATTR_NAMESPACE_SYSTEM_STRING;
                suffix = ":";
                break;
        case EXTATTR_NAMESPACE_EMPTY:
        default:
                return (EINVAL);
        }
        if (snprintf(attrname, size, "%s%s%s%s", prefix, namespace, suffix,
            name) >= size) {
                return (ENAMETOOLONG);
        }
        return (0);
}

/*
 * Vnode operating to retrieve a named extended attribute.
 */
static int
zfs_getextattr(struct vop_getextattr_args *ap)
/*
vop_getextattr {
        IN struct vnode *a_vp;
        IN int a_attrnamespace;
        IN const char *a_name;
        INOUT struct uio *a_uio;
        OUT size_t *a_size;
        IN struct ucred *a_cred;
        IN struct thread *a_td;
};
*/
{
        zfsvfs_t *zfsvfs = VTOZ(ap->a_vp)->z_zfsvfs;
        struct thread *td = ap->a_td;
        struct nameidata nd;
        char attrname[255];
        struct vattr va;
        vnode_t *xvp = NULL, *vp;
        int error, flags;

        error = extattr_check_cred(ap->a_vp, ap->a_attrnamespace,
            ap->a_cred, ap->a_td, VREAD);
        if (error != 0)
                return (error);

        error = zfs_create_attrname(ap->a_attrnamespace, ap->a_name, attrname,
            sizeof(attrname));
        if (error != 0)
                return (error);

        ZFS_ENTER(zfsvfs);

        error = zfs_lookup(ap->a_vp, NULL, &xvp, NULL, 0, ap->a_cred, td,
            LOOKUP_XATTR);
        if (error != 0) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        flags = FREAD;
        NDINIT_ATVP(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_SYSSPACE, attrname,
            xvp, td);
        error = vn_open_cred(&nd, &flags, 0, 0, ap->a_cred, NULL);
        vp = nd.ni_vp;
        NDFREE(&nd, NDF_ONLY_PNBUF);
        if (error != 0) {
                ZFS_EXIT(zfsvfs);
                if (error == ENOENT)
                        error = ENOATTR;
                return (error);
        }

        if (ap->a_size != NULL) {
                error = VOP_GETATTR(vp, &va, ap->a_cred);
                if (error == 0)
                        *ap->a_size = (size_t)va.va_size;
        } else if (ap->a_uio != NULL)
                error = VOP_READ(vp, ap->a_uio, IO_UNIT | IO_SYNC, ap->a_cred);

        VOP_UNLOCK(vp, 0);
        vn_close(vp, flags, ap->a_cred, td);
        ZFS_EXIT(zfsvfs);

        return (error);
}

/*
 * Vnode operation to remove a named attribute.
 */
int
zfs_deleteextattr(struct vop_deleteextattr_args *ap)
/*
vop_deleteextattr {
        IN struct vnode *a_vp;
        IN int a_attrnamespace;
        IN const char *a_name;
        IN struct ucred *a_cred;
        IN struct thread *a_td;
};
*/
{
        zfsvfs_t *zfsvfs = VTOZ(ap->a_vp)->z_zfsvfs;
        struct thread *td = ap->a_td;
        struct nameidata nd;
        char attrname[255];
        struct vattr va;
        vnode_t *xvp = NULL, *vp;
        int error, flags;

        error = extattr_check_cred(ap->a_vp, ap->a_attrnamespace,
            ap->a_cred, ap->a_td, VWRITE);
        if (error != 0)
                return (error);

        error = zfs_create_attrname(ap->a_attrnamespace, ap->a_name, attrname,
            sizeof(attrname));
        if (error != 0)
                return (error);

        ZFS_ENTER(zfsvfs);

        error = zfs_lookup(ap->a_vp, NULL, &xvp, NULL, 0, ap->a_cred, td,
            LOOKUP_XATTR);
        if (error != 0) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        NDINIT_ATVP(&nd, DELETE, NOFOLLOW | LOCKPARENT | LOCKLEAF | MPSAFE,
            UIO_SYSSPACE, attrname, xvp, td);
        error = namei(&nd);
        vp = nd.ni_vp;
        NDFREE(&nd, NDF_ONLY_PNBUF);
        if (error != 0) {
                ZFS_EXIT(zfsvfs);
                if (error == ENOENT)
                        error = ENOATTR;
                return (error);
        }
        error = VOP_REMOVE(nd.ni_dvp, vp, &nd.ni_cnd);

        vput(nd.ni_dvp);
        if (vp == nd.ni_dvp)
                vrele(vp);
        else
                vput(vp);
        ZFS_EXIT(zfsvfs);

        return (error);
}

/*
 * Vnode operation to set a named attribute.
 */
static int
zfs_setextattr(struct vop_setextattr_args *ap)
/*
vop_setextattr {
        IN struct vnode *a_vp;
        IN int a_attrnamespace;
        IN const char *a_name;
        INOUT struct uio *a_uio;
        IN struct ucred *a_cred;
        IN struct thread *a_td;
};
*/
{
        zfsvfs_t *zfsvfs = VTOZ(ap->a_vp)->z_zfsvfs;
        struct thread *td = ap->a_td;
        struct nameidata nd;
        char attrname[255];
        struct vattr va;
        vnode_t *xvp = NULL, *vp;
        int error, flags;

        error = extattr_check_cred(ap->a_vp, ap->a_attrnamespace,
            ap->a_cred, ap->a_td, VWRITE);
        if (error != 0)
                return (error);

        error = zfs_create_attrname(ap->a_attrnamespace, ap->a_name, attrname,
            sizeof(attrname));
        if (error != 0)
                return (error);

        ZFS_ENTER(zfsvfs);

        error = zfs_lookup(ap->a_vp, NULL, &xvp, NULL, 0, ap->a_cred, td,
            LOOKUP_XATTR | CREATE_XATTR_DIR);
        if (error != 0) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        flags = FFLAGS(O_WRONLY | O_CREAT);
        NDINIT_ATVP(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_SYSSPACE, attrname,
            xvp, td);
        error = vn_open_cred(&nd, &flags, 0600, 0, ap->a_cred, NULL);
        vp = nd.ni_vp;
        NDFREE(&nd, NDF_ONLY_PNBUF);
        if (error != 0) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        VATTR_NULL(&va);
        va.va_size = 0;
        error = VOP_SETATTR(vp, &va, ap->a_cred);
        if (error == 0)
                VOP_WRITE(vp, ap->a_uio, IO_UNIT | IO_SYNC, ap->a_cred);

        VOP_UNLOCK(vp, 0);
        vn_close(vp, flags, ap->a_cred, td);
        ZFS_EXIT(zfsvfs);

        return (error);
}

/*
 * Vnode operation to retrieve extended attributes on a vnode.
 */
static int
zfs_listextattr(struct vop_listextattr_args *ap)
/*
vop_listextattr {
        IN struct vnode *a_vp;
        IN int a_attrnamespace;
        INOUT struct uio *a_uio;
        OUT size_t *a_size;
        IN struct ucred *a_cred;
        IN struct thread *a_td;
};
*/
{
        zfsvfs_t *zfsvfs = VTOZ(ap->a_vp)->z_zfsvfs;
        struct thread *td = ap->a_td;
        struct nameidata nd;
        char attrprefix[16];
        u_char dirbuf[sizeof(struct dirent)];
        struct dirent *dp;
        struct iovec aiov;
        struct uio auio, *uio = ap->a_uio;
        size_t *sizep = ap->a_size;
        size_t plen;
        vnode_t *xvp = NULL, *vp;
        int done, error, eof, pos;

        error = extattr_check_cred(ap->a_vp, ap->a_attrnamespace,
            ap->a_cred, ap->a_td, VREAD);
        if (error != 0)
                return (error);

        error = zfs_create_attrname(ap->a_attrnamespace, "", attrprefix,
            sizeof(attrprefix));
        if (error != 0)
                return (error);
        plen = strlen(attrprefix);

        ZFS_ENTER(zfsvfs);

        if (sizep != NULL)
                *sizep = 0;

        error = zfs_lookup(ap->a_vp, NULL, &xvp, NULL, 0, ap->a_cred, td,
            LOOKUP_XATTR);
        if (error != 0) {
                ZFS_EXIT(zfsvfs);
                /*
                 * ENOATTR means that the EA directory does not yet exist,
                 * i.e. there are no extended attributes there.
                 */
                if (error == ENOATTR)
                        error = 0;
                return (error);
        }

        NDINIT_ATVP(&nd, LOOKUP, NOFOLLOW | LOCKLEAF | LOCKSHARED | MPSAFE,
            UIO_SYSSPACE, ".", xvp, td);
        error = namei(&nd);
        vp = nd.ni_vp;
        NDFREE(&nd, NDF_ONLY_PNBUF);
        if (error != 0) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        auio.uio_segflg = UIO_SYSSPACE;
        auio.uio_td = td;
        auio.uio_rw = UIO_READ;
        auio.uio_offset = 0;

        do {
                u_char nlen;

                aiov.iov_base = (void *)dirbuf;
                aiov.iov_len = sizeof(dirbuf);
                auio.uio_resid = sizeof(dirbuf);
                error = VOP_READDIR(vp, &auio, ap->a_cred, &eof, NULL, NULL);
                done = sizeof(dirbuf) - auio.uio_resid;
                if (error != 0)
                        break;
                for (pos = 0; pos < done;) {
                        dp = (struct dirent *)(dirbuf + pos);
                        pos += dp->d_reclen;
                        /*
                         * XXX: Temporarily we also accept DT_UNKNOWN, as this
                         * is what we get when attribute was created on Solaris.
                         */
                        if (dp->d_type != DT_REG && dp->d_type != DT_UNKNOWN)
                                continue;
                        if (plen == 0 && strncmp(dp->d_name, "freebsd:", 8) == 0)
                                continue;
                        else if (strncmp(dp->d_name, attrprefix, plen) != 0)
                                continue;
                        nlen = dp->d_namlen - plen;
                        if (sizep != NULL)
                                *sizep += 1 + nlen;
                        else if (uio != NULL) {
                                /*
                                 * Format of extattr name entry is one byte for
                                 * length and the rest for name.
                                 */
                                error = uiomove(&nlen, 1, uio->uio_rw, uio);
                                if (error == 0) {
                                        error = uiomove(dp->d_name + plen, nlen,
                                            uio->uio_rw, uio);
                                }
                                if (error != 0)
                                        break;
                        }
                }
        } while (!eof && error == 0);

        vput(vp);
        ZFS_EXIT(zfsvfs);

        return (error);
}

int
zfs_freebsd_getacl(ap)
        struct vop_getacl_args /* {
                struct vnode *vp;
                acl_type_t type;
                struct acl *aclp;
                struct ucred *cred;
                struct thread *td;
        } */ *ap;
{
        int             error;
        vsecattr_t      vsecattr;

        if (ap->a_type != ACL_TYPE_NFS4)
                return (EINVAL);

        vsecattr.vsa_mask = VSA_ACE | VSA_ACECNT;
        if (error = zfs_getsecattr(ap->a_vp, &vsecattr, 0, ap->a_cred, NULL))
                return (error);

        error = acl_from_aces(ap->a_aclp, vsecattr.vsa_aclentp, vsecattr.vsa_aclcnt);
        if (vsecattr.vsa_aclentp != NULL)
                kmem_free(vsecattr.vsa_aclentp, vsecattr.vsa_aclentsz);

        return (error);
}

int
zfs_freebsd_setacl(ap)
        struct vop_setacl_args /* {
                struct vnode *vp;
                acl_type_t type;
                struct acl *aclp;
                struct ucred *cred;
                struct thread *td;
        } */ *ap;
{
        int             error;
        vsecattr_t      vsecattr;
        int             aclbsize;       /* size of acl list in bytes */
        aclent_t        *aaclp;

        if (ap->a_type != ACL_TYPE_NFS4)
                return (EINVAL);

        if (ap->a_aclp->acl_cnt < 1 || ap->a_aclp->acl_cnt > MAX_ACL_ENTRIES)
                return (EINVAL);

        /*
         * With NFSv4 ACLs, chmod(2) may need to add additional entries,
         * splitting every entry into two and appending "canonical six"
         * entries at the end.  Don't allow for setting an ACL that would
         * cause chmod(2) to run out of ACL entries.
         */
        if (ap->a_aclp->acl_cnt * 2 + 6 > ACL_MAX_ENTRIES)
                return (ENOSPC);

        error = acl_nfs4_check(ap->a_aclp, ap->a_vp->v_type == VDIR);
        if (error != 0)
                return (error);

        vsecattr.vsa_mask = VSA_ACE;
        aclbsize = ap->a_aclp->acl_cnt * sizeof(ace_t);
        vsecattr.vsa_aclentp = kmem_alloc(aclbsize, KM_SLEEP);
        aaclp = vsecattr.vsa_aclentp;
        vsecattr.vsa_aclentsz = aclbsize;

        aces_from_acl(vsecattr.vsa_aclentp, &vsecattr.vsa_aclcnt, ap->a_aclp);
        error = zfs_setsecattr(ap->a_vp, &vsecattr, 0, ap->a_cred, NULL);
        kmem_free(aaclp, aclbsize);

        return (error);
}

int
zfs_freebsd_aclcheck(ap)
        struct vop_aclcheck_args /* {
                struct vnode *vp;
                acl_type_t type;
                struct acl *aclp;
                struct ucred *cred;
                struct thread *td;
        } */ *ap;
{

        return (EOPNOTSUPP);
}

struct vop_vector zfs_vnodeops;
struct vop_vector zfs_fifoops;
struct vop_vector zfs_shareops;

struct vop_vector zfs_vnodeops = {
        .vop_default =          &default_vnodeops,
        .vop_inactive =         zfs_freebsd_inactive,
        .vop_reclaim =          zfs_freebsd_reclaim,
        .vop_access =           zfs_freebsd_access,
#ifdef FREEBSD_NAMECACHE
        .vop_lookup =           vfs_cache_lookup,
        .vop_cachedlookup =     zfs_freebsd_lookup,
#else
        .vop_lookup =           zfs_freebsd_lookup,
#endif
        .vop_getattr =          zfs_freebsd_getattr,
        .vop_setattr =          zfs_freebsd_setattr,
        .vop_create =           zfs_freebsd_create,
        .vop_mknod =            zfs_freebsd_create,
        .vop_mkdir =            zfs_freebsd_mkdir,
        .vop_readdir =          zfs_freebsd_readdir,
        .vop_fsync =            zfs_freebsd_fsync,
        .vop_open =             zfs_freebsd_open,
        .vop_close =            zfs_freebsd_close,
        .vop_rmdir =            zfs_freebsd_rmdir,
        .vop_ioctl =            zfs_freebsd_ioctl,
        .vop_link =             zfs_freebsd_link,
        .vop_symlink =          zfs_freebsd_symlink,
        .vop_readlink =         zfs_freebsd_readlink,
        .vop_read =             zfs_freebsd_read,
        .vop_write =            zfs_freebsd_write,
        .vop_remove =           zfs_freebsd_remove,
        .vop_rename =           zfs_freebsd_rename,
        .vop_pathconf =         zfs_freebsd_pathconf,
        .vop_bmap =             VOP_EOPNOTSUPP,
        .vop_fid =              zfs_freebsd_fid,
        .vop_getextattr =       zfs_getextattr,
        .vop_deleteextattr =    zfs_deleteextattr,
        .vop_setextattr =       zfs_setextattr,
        .vop_listextattr =      zfs_listextattr,
        .vop_getacl =           zfs_freebsd_getacl,
        .vop_setacl =           zfs_freebsd_setacl,
        .vop_aclcheck =         zfs_freebsd_aclcheck,
};

struct vop_vector zfs_fifoops = {
        .vop_default =          &fifo_specops,
        .vop_fsync =            zfs_freebsd_fsync,
        .vop_access =           zfs_freebsd_access,
        .vop_getattr =          zfs_freebsd_getattr,
        .vop_inactive =         zfs_freebsd_inactive,
        .vop_read =             VOP_PANIC,
        .vop_reclaim =          zfs_freebsd_reclaim,
        .vop_setattr =          zfs_freebsd_setattr,
        .vop_write =            VOP_PANIC,
        .vop_pathconf =         zfs_freebsd_fifo_pathconf,
        .vop_fid =              zfs_freebsd_fid,
        .vop_getacl =           zfs_freebsd_getacl,
        .vop_setacl =           zfs_freebsd_setacl,
        .vop_aclcheck =         zfs_freebsd_aclcheck,
};

/*
 * special share hidden files vnode operations template
 */
struct vop_vector zfs_shareops = {
        .vop_default =          &default_vnodeops,
        .vop_access =           zfs_freebsd_access,
        .vop_inactive =         zfs_freebsd_inactive,
        .vop_reclaim =          zfs_freebsd_reclaim,
        .vop_fid =              zfs_freebsd_fid,
        .vop_pathconf =         zfs_freebsd_pathconf,
};