MFZoL: Retire send space estimation via ZFS_IOC_SEND

[FreeBSD/FreeBSD.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.
 * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
 * Copyright (c) 2014 Integros [integros.com]
 * Copyright 2017 Nexenta Systems, Inc.
 */

/* Portions Copyright 2007 Jeremy Teo */
/* Portions Copyright 2010 Robert Milkowski */

#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/vm.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/dmu_objset.h>
#include <sys/spa.h>
#include <sys/txg.h>
#include <sys/dbuf.h>
#include <sys/zap.h>
#include <sys/sa.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/zfs_sa.h>
#include <sys/zfs_rlock.h>
#include <sys/extdirent.h>
#include <sys/kidmap.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/sched.h>
#include <sys/acl.h>
#include <sys/vmmeter.h>
#include <vm/vm_param.h>
#include <sys/zil.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) If ZPL locks are held, pass TXG_NOWAIT as the second argument to
 *      dmu_tx_assign().  This is critical because we don't want to block
 *      while holding locks.
 *
 *      If no ZPL locks are held (aside from ZFS_ENTER()), use TXG_WAIT.  This
 *      reduces lock contention and CPU usage when we must wait (note that if
 *      throughput is constrained by the storage, nearly every transaction
 *      must wait).
 *
 *      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.  On subsequent
 *      calls to dmu_tx_assign(), pass TXG_NOTHROTTLE in addition to TXG_NOWAIT,
 *      to indicate that this operation has already called dmu_tx_wait().
 *      This will ensure that we don't retry forever, waiting a short bit
 *      each time.
 *
 *  (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, 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_lookup(&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, (waited ? TXG_NOTHROTTLE : 0) | TXG_NOWAIT);
 *      if (error) {
 *              rw_exit(...);           // drop locks
 *              zfs_dirent_unlock(dl);  // unlock directory entry
 *              VN_RELE(...);           // release held vnodes
 *              if (error == ERESTART) {
 *                      waited = B_TRUE;
 *                      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, 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_pflags & ZFS_APPENDONLY) &&
            ((flag & FAPPEND) == 0)) {
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EPERM));
        }

        if (!zfs_has_ctldir(zp) && zp->z_zfsvfs->z_vscan &&
            ZTOV(zp)->v_type == VREG &&
            !(zp->z_pflags & ZFS_AV_QUARANTINED) && zp->z_size > 0) {
                if (fs_vscan(*vpp, cr, 0) != 0) {
                        ZFS_EXIT(zfsvfs);
                        return (SET_ERROR(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;

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

        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);

        if (!zfs_has_ctldir(zp) && zp->z_zfsvfs->z_vscan &&
            ZTOV(zp)->v_type == VREG &&
            !(zp->z_pflags & ZFS_AV_QUARANTINED) && zp->z_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_size;
        if (noff >= file_sz)  {
                return (SET_ERROR(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);

        if (error == ESRCH)
                return (SET_ERROR(ENXIO));

        /*
         * We could find a hole that begins after the logical end-of-file,
         * because dmu_offset_next() only works on whole blocks.  If the
         * EOF falls mid-block, then indicate that the "virtual hole"
         * at the end of the file begins at the logical EOF, rather than
         * at the end of the last block.
         */
        if (noff > file_sz) {
                ASSERT(hole);
                noff = file_sz;
        }

        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;
        offset_t ndata;
        dmu_object_info_t doi;
        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:
        {
#ifdef illumos
                if (ddi_copyin((void *)data, &off, sizeof (off), flag))
                        return (SET_ERROR(EFAULT));
#else
                off = *(offset_t *)data;
#endif
                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);
#ifdef illumos
                if (ddi_copyout(&off, (void *)data, sizeof (off), flag))
                        return (SET_ERROR(EFAULT));
#else
                *(offset_t *)data = off;
#endif
                return (0);
        }
#ifdef illumos
        case _FIO_COUNT_FILLED:
        {
                /*
                 * _FIO_COUNT_FILLED adds a new ioctl command which
                 * exposes the number of filled blocks in a
                 * ZFS object.
                 */
                zp = VTOZ(vp);
                zfsvfs = zp->z_zfsvfs;
                ZFS_ENTER(zfsvfs);
                ZFS_VERIFY_ZP(zp);

                /*
                 * Wait for all dirty blocks for this object
                 * to get synced out to disk, and the DMU info
                 * updated.
                 */
                error = dmu_object_wait_synced(zfsvfs->z_os, zp->z_id);
                if (error) {
                        ZFS_EXIT(zfsvfs);
                        return (error);
                }

                /*
                 * Retrieve fill count from DMU object.
                 */
                error = dmu_object_info(zfsvfs->z_os, zp->z_id, &doi);
                if (error) {
                        ZFS_EXIT(zfsvfs);
                        return (error);
                }

                ndata = doi.doi_fill_count;

                ZFS_EXIT(zfsvfs);
                if (ddi_copyout(&ndata, (void *)data, sizeof (ndata), flag))
                        return (SET_ERROR(EFAULT));
                return (0);
        }
#endif
        }
        return (SET_ERROR(ENOTTY));
}

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

        /*
         * At present vm_page_clear_dirty extends the cleared range to DEV_BSIZE
         * aligned boundaries, if the range is not aligned.  As a result a
         * DEV_BSIZE subrange with partially dirty data may get marked as clean.
         * It may happen that all DEV_BSIZE subranges are marked clean and thus
         * the whole page would be considred clean despite have some dirty data.
         * For this reason we should shrink the range to DEV_BSIZE aligned
         * boundaries before calling vm_page_clear_dirty.
         */
        end = rounddown2(off + nbytes, DEV_BSIZE);
        off = roundup2(off, DEV_BSIZE);
        nbytes = end - off;

        obj = vp->v_object;
        zfs_vmobject_assert_wlocked(obj);

        vm_page_grab_valid(&pp, obj, OFF_TO_IDX(start), VM_ALLOC_NOCREAT |
            VM_ALLOC_SBUSY | VM_ALLOC_NORMAL | VM_ALLOC_IGN_SBUSY);
        if (pp != NULL) {
                ASSERT3U(pp->valid, ==, VM_PAGE_BITS_ALL);
                vm_object_pip_add(obj, 1);
                pmap_remove_write(pp);
                if (nbytes != 0)
                        vm_page_clear_dirty(pp, off, nbytes);
        }
        return (pp);
}

static void
page_unbusy(vm_page_t pp)
{

        vm_page_sunbusy(pp);
        vm_object_pip_wakeup(pp->object);
}

static vm_page_t
page_wire(vnode_t *vp, int64_t start)
{
        vm_object_t obj;
        vm_page_t m;

        obj = vp->v_object;
        zfs_vmobject_assert_wlocked(obj);

        vm_page_grab_valid(&m, obj, OFF_TO_IDX(start), VM_ALLOC_NOCREAT |
            VM_ALLOC_WIRED | VM_ALLOC_IGN_SBUSY | VM_ALLOC_NOBUSY);
        return (m);
}

static void
page_unwire(vm_page_t pp)
{

        vm_page_unwire(pp, PQ_ACTIVE);
}

/*
 * 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;
        caddr_t va;
        int off;

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

        off = start & PAGEOFFSET;
        zfs_vmobject_wlock(obj);
        vm_object_pip_add(obj, 1);
        for (start &= PAGEMASK; len > 0; start += PAGESIZE) {
                vm_page_t pp;
                int nbytes = imin(PAGESIZE - off, len);

                if ((pp = page_busy(vp, start, off, nbytes)) != NULL) {
                        zfs_vmobject_wunlock(obj);

                        va = zfs_map_page(pp, &sf);
                        (void) dmu_read(os, oid, start+off, nbytes,
                            va+off, DMU_READ_PREFETCH);;
                        zfs_unmap_page(sf);

                        zfs_vmobject_wlock(obj);
                        page_unbusy(pp);
                }
                len -= nbytes;
                off = 0;
        }
        vm_object_pip_wakeup(obj);
        zfs_vmobject_wunlock(obj);
}

/*
 * Read with UIO_NOCOPY flag means that sendfile(2) requests
 * ZFS to populate a range of page cache pages with data.
 *
 * NOTE: this function could be optimized to pre-allocate
 * all pages in advance, drain exclusive busy on all of them,
 * map them into contiguous KVA region and populate them
 * in one single dmu_read() call.
 */
static int
mappedread_sf(vnode_t *vp, int nbytes, uio_t *uio)
{
        znode_t *zp = VTOZ(vp);
        objset_t *os = zp->z_zfsvfs->z_os;
        struct sf_buf *sf;
        vm_object_t obj;
        vm_page_t pp;
        int64_t start;
        caddr_t va;
        int len = nbytes;
        int off;
        int error = 0;

        ASSERT(uio->uio_segflg == UIO_NOCOPY);
        ASSERT(vp->v_mount != NULL);
        obj = vp->v_object;
        ASSERT(obj != NULL);
        ASSERT((uio->uio_loffset & PAGEOFFSET) == 0);

        zfs_vmobject_wlock(obj);
        for (start = uio->uio_loffset; len > 0; start += PAGESIZE) {
                int bytes = MIN(PAGESIZE, len);

                pp = vm_page_grab(obj, OFF_TO_IDX(start), VM_ALLOC_SBUSY |
                    VM_ALLOC_NORMAL | VM_ALLOC_IGN_SBUSY);
                if (pp->valid == 0) {
                        zfs_vmobject_wunlock(obj);
                        va = zfs_map_page(pp, &sf);
                        error = dmu_read(os, zp->z_id, start, bytes, va,
                            DMU_READ_PREFETCH);
                        if (bytes != PAGESIZE && error == 0)
                                bzero(va + bytes, PAGESIZE - bytes);
                        zfs_unmap_page(sf);
                        zfs_vmobject_wlock(obj);
                        vm_page_sunbusy(pp);
                        if (error) {
                                if (!vm_page_busied(pp) && !vm_page_wired(pp) &&
                                    pp->valid == 0)
                                        vm_page_free(pp);
                        } else {
                                pp->valid = VM_PAGE_BITS_ALL;
                                vm_page_lock(pp);
                                vm_page_activate(pp);
                                vm_page_unlock(pp);
                        }
                } else {
                        ASSERT3U(pp->valid, ==, VM_PAGE_BITS_ALL);
                        vm_page_sunbusy(pp);
                }
                if (error)
                        break;
                uio->uio_resid -= bytes;
                uio->uio_offset += bytes;
                len -= bytes;
        }
        zfs_vmobject_wunlock(obj);
        return (error);
}

/*
 * 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);
        vm_object_t obj;
        int64_t start;
        caddr_t va;
        int len = nbytes;
        int off;
        int error = 0;

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

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

                if (pp = page_wire(vp, start)) {
                        struct sf_buf *sf;
                        caddr_t va;

                        zfs_vmobject_wunlock(obj);
                        va = zfs_map_page(pp, &sf);
#ifdef illumos
                        error = uiomove(va + off, bytes, UIO_READ, uio);
#else
                        error = vn_io_fault_uiomove(va + off, bytes, uio);
#endif
                        zfs_unmap_page(sf);
                        zfs_vmobject_wlock(obj);
                        page_unwire(pp);
                } else {
                        zfs_vmobject_wunlock(obj);
                        error = dmu_read_uio_dbuf(sa_get_db(zp->z_sa_hdl),
                            uio, bytes);
                        zfs_vmobject_wlock(obj);
                }
                len -= bytes;
                off = 0;
                if (error)
                        break;
        }
        zfs_vmobject_wunlock(obj);
        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 on success, error code on 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;
        ssize_t         n, nbytes;
        int             error = 0;
        rl_t            *rl;
        xuio_t          *xuio = NULL;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        if (zp->z_pflags & ZFS_AV_QUARANTINED) {
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EACCES));
        }

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

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

        /*
         * Check for mandatory locks
         */
        if (MANDMODE(zp->z_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 (zfsvfs->z_log &&
            (ioflag & FRSYNC || zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS))
                zil_commit(zfsvfs->z_log, 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_size) {
                error = 0;
                goto out;
        }

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

#ifdef illumos
        if ((uio->uio_extflg == UIO_XUIO) &&
            (((xuio_t *)uio)->xu_type == UIOTYPE_ZEROCOPY)) {
                int nblk;
                int blksz = zp->z_blksz;
                uint64_t offset = uio->uio_loffset;

                xuio = (xuio_t *)uio;
                if ((ISP2(blksz))) {
                        nblk = (P2ROUNDUP(offset + n, blksz) - P2ALIGN(offset,
                            blksz)) / blksz;
                } else {
                        ASSERT(offset + n <= blksz);
                        nblk = 1;
                }
                (void) dmu_xuio_init(xuio, nblk);

                if (vn_has_cached_data(vp)) {
                        /*
                         * For simplicity, we always allocate a full buffer
                         * even if we only expect to read a portion of a block.
                         */
                        while (--nblk >= 0) {
                                (void) dmu_xuio_add(xuio,
                                    dmu_request_arcbuf(sa_get_db(zp->z_sa_hdl),
                                    blksz), 0, blksz);
                        }
                }
        }
#endif  /* illumos */

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

#ifdef __FreeBSD__
                if (uio->uio_segflg == UIO_NOCOPY)
                        error = mappedread_sf(vp, nbytes, uio);
                else
#endif /* __FreeBSD__ */
                if (vn_has_cached_data(vp)) {
                        error = mappedread(vp, nbytes, uio);
                } else {
                        error = dmu_read_uio_dbuf(sa_get_db(zp->z_sa_hdl),
                            uio, nbytes);
                }
                if (error) {
                        /* convert checksum errors into IO errors */
                        if (error == ECKSUM)
                                error = SET_ERROR(EIO);
                        break;
                }

                n -= nbytes;
        }
out:
        zfs_range_unlock(rl);

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

/*
 * 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  - FAPPEND, FSYNC, and/or FDSYNC.  FAPPEND is
 *                        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 on success, error code on 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;
        int             error = 0;
        arc_buf_t       *abuf;
        iovec_t         *aiov = NULL;
        xuio_t          *xuio = NULL;
        int             i_iov = 0;
        int             iovcnt = uio->uio_iovcnt;
        iovec_t         *iovp = uio->uio_iov;
        int             write_eof;
        int             count = 0;
        sa_bulk_attr_t  bulk[4];
        uint64_t        mtime[2], ctime[2];

        /*
         * 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);

        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs), NULL, &mtime, 16);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL, &ctime, 16);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_SIZE(zfsvfs), NULL,
            &zp->z_size, 8);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs), NULL,
            &zp->z_pflags, 8);

        /*
         * In a case vp->v_vfsp != zp->z_zfsvfs->z_vfs (e.g. snapshots) our
         * callers might not be able to detect properly that we are read-only,
         * so check it explicitly here.
         */
        if (zfsvfs->z_vfs->vfs_flag & VFS_RDONLY) {
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EROFS));
        }

        /*
         * If immutable or not appending then return EPERM.
         * Intentionally allow ZFS_READONLY through here.
         * See zfs_zaccess_common()
         */
        if ((zp->z_pflags & ZFS_IMMUTABLE) ||
            ((zp->z_pflags & ZFS_APPENDONLY) && !(ioflag & FAPPEND) &&
            (uio->uio_loffset < zp->z_size))) {
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EPERM));
        }

        zilog = zfsvfs->z_log;

        /*
         * Validate file offset
         */
        woff = ioflag & FAPPEND ? zp->z_size : uio->uio_loffset;
        if (woff < 0) {
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EINVAL));
        }

        /*
         * Check for mandatory locks before calling zfs_range_lock()
         * in order to prevent a deadlock with locks set via fcntl().
         */
        if (MANDMODE((mode_t)zp->z_mode) &&
            (error = chklock(vp, FWRITE, woff, n, uio->uio_fmode, ct)) != 0) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

#ifdef illumos
        /*
         * Pre-fault the pages to ensure slow (eg NFS) pages
         * don't hold up txg.
         * Skip this if uio contains loaned arc_buf.
         */
        if ((uio->uio_extflg == UIO_XUIO) &&
            (((xuio_t *)uio)->xu_type == UIOTYPE_ZEROCOPY))
                xuio = (xuio_t *)uio;
        else
                uio_prefaultpages(MIN(n, max_blksz), uio);
#endif

        /*
         * If in append mode, set the io offset pointer to eof.
         */
        if (ioflag & FAPPEND) {
                /*
                 * Obtain an appending range lock to guarantee file append
                 * semantics.  We reset the write offset once we have the lock.
                 */
                rl = zfs_range_lock(zp, 0, n, RL_APPEND);
                woff = rl->r_off;
                if (rl->r_len == UINT64_MAX) {
                        /*
                         * We overlocked the file because this write will cause
                         * the file block size to increase.
                         * Note that zp_size cannot change with this lock held.
                         */
                        woff = zp->z_size;
                }
                uio->uio_loffset = woff;
        } else {
                /*
                 * Note that if the file block size will change as a result of
                 * this write, then this range lock will lock the entire file
                 * so that we can re-write the block safely.
                 */
                rl = zfs_range_lock(zp, woff, n, RL_WRITER);
        }

        if (vn_rlimit_fsize(vp, uio, uio->uio_td)) {
                zfs_range_unlock(rl);
                ZFS_EXIT(zfsvfs);
                return (EFBIG);
        }

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

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

        /* Will this write extend the file length? */
        write_eof = (woff + n > zp->z_size);

        end_size = MAX(zp->z_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;
                if (zfs_owner_overquota(zfsvfs, zp, B_FALSE) ||
                    zfs_owner_overquota(zfsvfs, zp, B_TRUE)) {
                        if (abuf != NULL)
                                dmu_return_arcbuf(abuf);
                        error = SET_ERROR(EDQUOT);
                        break;
                }

                if (xuio && abuf == NULL) {
                        ASSERT(i_iov < iovcnt);
                        aiov = &iovp[i_iov];
                        abuf = dmu_xuio_arcbuf(xuio, i_iov);
                        dmu_xuio_clear(xuio, i_iov);
                        DTRACE_PROBE3(zfs_cp_write, int, i_iov,
                            iovec_t *, aiov, arc_buf_t *, abuf);
                        ASSERT((aiov->iov_base == abuf->b_data) ||
                            ((char *)aiov->iov_base - (char *)abuf->b_data +
                            aiov->iov_len == arc_buf_size(abuf)));
                        i_iov++;
                } else if (abuf == NULL && n >= max_blksz &&
                    woff >= zp->z_size &&
                    P2PHASE(woff, max_blksz) == 0 &&
                    zp->z_blksz == max_blksz) {
                        /*
                         * This write covers a full block.  "Borrow" a buffer
                         * from the dmu so that we can fill it before we enter
                         * a transaction.  This avoids the possibility of
                         * holding up the transaction if the data copy hangs
                         * up on a pagefault (e.g., from an NFS server mapping).
                         */
                        size_t cbytes;

                        abuf = dmu_request_arcbuf(sa_get_db(zp->z_sa_hdl),
                            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_sa(tx, zp->z_sa_hdl, B_FALSE);
                dmu_tx_hold_write(tx, zp->z_id, woff, MIN(n, max_blksz));
                zfs_sa_upgrade_txholds(tx, zp);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        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) {
                                /*
                                 * File's blocksize is already larger than the
                                 * "recordsize" property.  Only let it grow to
                                 * the next power of 2.
                                 */
                                ASSERT(!ISP2(zp->z_blksz));
                                new_blksz = MIN(end_size,
                                    1 << highbit64(zp->z_blksz));
                        } 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_size)
                        vnode_pager_setsize(vp, woff + nbytes);

                if (abuf == NULL) {
                        tx_bytes = uio->uio_resid;
                        error = dmu_write_uio_dbuf(sa_get_db(zp->z_sa_hdl),
                            uio, nbytes, tx);
                        tx_bytes -= uio->uio_resid;
                } else {
                        tx_bytes = nbytes;
                        ASSERT(xuio == NULL || tx_bytes == aiov->iov_len);
                        /*
                         * If this is not a full block write, but we are
                         * extending the file past EOF and this data starts
                         * block-aligned, use assign_arcbuf().  Otherwise,
                         * write via dmu_write().
                         */
                        if (tx_bytes < max_blksz && (!write_eof ||
                            aiov->iov_base != abuf->b_data)) {
                                ASSERT(xuio);
                                dmu_write(zfsvfs->z_os, zp->z_id, woff,
                                    aiov->iov_len, aiov->iov_base, tx);
                                dmu_return_arcbuf(abuf);
                                xuio_stat_wbuf_copied();
                        } else {
                                ASSERT(xuio || tx_bytes == max_blksz);
                                dmu_assign_arcbuf(sa_get_db(zp->z_sa_hdl),
                                    woff, abuf, tx);
                        }
                        ASSERT(tx_bytes <= uio->uio_resid);
                        uioskip(uio, tx_bytes);
                }
                if (tx_bytes && vn_has_cached_data(vp)) {
                        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) {
                        (void) sa_update(zp->z_sa_hdl, SA_ZPL_SIZE(zfsvfs),
                            (void *)&zp->z_size, sizeof (uint64_t), tx);
                        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_mode & (S_IXUSR | (S_IXUSR >> 3) |
                    (S_IXUSR >> 6))) != 0 &&
                    (zp->z_mode & (S_ISUID | S_ISGID)) != 0 &&
                    secpolicy_vnode_setid_retain(vp, cr,
                    (zp->z_mode & S_ISUID) != 0 && zp->z_uid == 0) != 0) {
                        uint64_t newmode;
                        zp->z_mode &= ~(S_ISUID | S_ISGID);
                        newmode = zp->z_mode;
                        (void) sa_update(zp->z_sa_hdl, SA_ZPL_MODE(zfsvfs),
                            (void *)&newmode, sizeof (uint64_t), tx);
                }
                mutex_exit(&zp->z_acl_lock);

                zfs_tstamp_update_setup(zp, CONTENT_MODIFIED, mtime, ctime,
                    B_TRUE);

                /*
                 * Update the file size (zp_size) if it has changed;
                 * account for possible concurrent updates.
                 */
                while ((end_size = zp->z_size) < uio->uio_loffset) {
                        (void) atomic_cas_64(&zp->z_size, end_size,
                            uio->uio_loffset);
#ifdef illumos
                        ASSERT(error == 0);
#else
                        ASSERT(error == 0 || error == EFAULT);
#endif
                }
                /*
                 * If we are replaying and eof is non zero then force
                 * the file size to the specified eof. Note, there's no
                 * concurrency during replay.
                 */
                if (zfsvfs->z_replay && zfsvfs->z_replay_eof != 0)
                        zp->z_size = zfsvfs->z_replay_eof;

                if (error == 0)
                        error = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
                else
                        (void) sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);

                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;

#ifdef illumos
                if (!xuio && n > 0)
                        uio_prefaultpages(MIN(n, max_blksz), uio);
#endif
        }

        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);
        }

#ifdef __FreeBSD__
        /*
         * EFAULT means that at least one page of the source buffer was not
         * available.  VFS will re-try remaining I/O upon this error.
         */
        if (error == EFAULT) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }
#endif

        if (ioflag & (FSYNC | FDSYNC) ||
            zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, zp->z_id);

        ZFS_EXIT(zfsvfs);
        return (0);
}

/* ARGSUSED */
void
zfs_get_done(zgd_t *zgd, int error)
{
        znode_t *zp = zgd->zgd_private;
        objset_t *os = zp->z_zfsvfs->z_os;

        if (zgd->zgd_db)
                dmu_buf_rele(zgd->zgd_db, zgd);

        zfs_range_unlock(zgd->zgd_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)));

        kmem_free(zgd, sizeof (zgd_t));
}

#ifdef DEBUG
static int zil_fault_io = 0;
#endif

/*
 * Get data to generate a TX_WRITE intent log record.
 */
int
zfs_get_data(void *arg, lr_write_t *lr, char *buf, struct lwb *lwb, zio_t *zio)
{
        zfsvfs_t *zfsvfs = arg;
        objset_t *os = zfsvfs->z_os;
        znode_t *zp;
        uint64_t object = lr->lr_foid;
        uint64_t offset = lr->lr_offset;
        uint64_t size = lr->lr_length;
        dmu_buf_t *db;
        zgd_t *zgd;
        int error = 0;

        ASSERT3P(lwb, !=, NULL);
        ASSERT3P(zio, !=, NULL);
        ASSERT3U(size, !=, 0);

        /*
         * Nothing to do if the file has been removed
         */
        if (zfs_zget(zfsvfs, object, &zp) != 0)
                return (SET_ERROR(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 (SET_ERROR(ENOENT));
        }

        zgd = (zgd_t *)kmem_zalloc(sizeof (zgd_t), KM_SLEEP);
        zgd->zgd_lwb = lwb;
        zgd->zgd_private = zp;

        /*
         * 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 */
                zgd->zgd_rl = zfs_range_lock(zp, offset, size, RL_READER);
                /* test for truncation needs to be done while range locked */
                if (offset >= zp->z_size) {
                        error = SET_ERROR(ENOENT);
                } else {
                        error = dmu_read(os, object, offset, size, buf,
                            DMU_READ_NO_PREFETCH);
                }
                ASSERT(error == 0 || error == ENOENT);
        } else { /* indirect write */
                /*
                 * Have to lock the whole block to ensure when it's
                 * written out and its 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 (;;) {
                        uint64_t blkoff;
                        size = zp->z_blksz;
                        blkoff = ISP2(size) ? P2PHASE(offset, size) : offset;
                        offset -= blkoff;
                        zgd->zgd_rl = zfs_range_lock(zp, offset, size,
                            RL_READER);
                        if (zp->z_blksz == size)
                                break;
                        offset += blkoff;
                        zfs_range_unlock(zgd->zgd_rl);
                }
                /* test for truncation needs to be done while range locked */
                if (lr->lr_offset >= zp->z_size)
                        error = SET_ERROR(ENOENT);
#ifdef DEBUG
                if (zil_fault_io) {
                        error = SET_ERROR(EIO);
                        zil_fault_io = 0;
                }
#endif
                if (error == 0)
                        error = dmu_buf_hold(os, object, offset, zgd, &db,
                            DMU_READ_NO_PREFETCH);

                if (error == 0) {
                        blkptr_t *bp = &lr->lr_blkptr;

                        zgd->zgd_db = db;
                        zgd->zgd_bp = bp;

                        ASSERT(db->db_offset == offset);
                        ASSERT(db->db_size == size);

                        error = dmu_sync(zio, lr->lr_common.lrc_txg,
                            zfs_get_done, zgd);
                        ASSERT(error || lr->lr_length <= size);

                        /*
                         * On success, we need to wait for the write I/O
                         * 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 == 0)
                                return (0);

                        if (error == EALREADY) {
                                lr->lr_common.lrc_txtype = TX_WRITE2;
                                /*
                                 * TX_WRITE2 relies on the data previously
                                 * written by the TX_WRITE that caused
                                 * EALREADY.  We zero out the BP because
                                 * it is the old, currently-on-disk BP.
                                 */
                                zgd->zgd_bp = NULL;
                                BP_ZERO(bp);
                                error = 0;
                        }
                }
        }

        zfs_get_done(zgd, error);

        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);
}

static int
zfs_dd_callback(struct mount *mp, void *arg, int lkflags, struct vnode **vpp)
{
        int error;

        *vpp = arg;
        error = vn_lock(*vpp, lkflags);
        if (error != 0)
                vrele(*vpp);
        return (error);
}

static int
zfs_lookup_lock(vnode_t *dvp, vnode_t *vp, const char *name, int lkflags)
{
        znode_t *zdp = VTOZ(dvp);
        zfsvfs_t *zfsvfs = zdp->z_zfsvfs;
        int error;
        int ltype;

        ASSERT_VOP_LOCKED(dvp, __func__);
#ifdef DIAGNOSTIC
        if ((zdp->z_pflags & ZFS_XATTR) == 0)
                VERIFY(!RRM_LOCK_HELD(&zfsvfs->z_teardown_lock));
#endif

        if (name[0] == 0 || (name[0] == '.' && name[1] == 0)) {
                ASSERT3P(dvp, ==, vp);
                vref(dvp);
                ltype = lkflags & LK_TYPE_MASK;
                if (ltype != VOP_ISLOCKED(dvp)) {
                        if (ltype == LK_EXCLUSIVE)
                                vn_lock(dvp, LK_UPGRADE | LK_RETRY);
                        else /* if (ltype == LK_SHARED) */
                                vn_lock(dvp, LK_DOWNGRADE | LK_RETRY);

                        /*
                         * Relock for the "." case could leave us with
                         * reclaimed vnode.
                         */
                        if (dvp->v_iflag & VI_DOOMED) {
                                vrele(dvp);
                                return (SET_ERROR(ENOENT));
                        }
                }
                return (0);
        } else if (name[0] == '.' && name[1] == '.' && name[2] == 0) {
                /*
                 * Note that in this case, dvp is the child vnode, and we
                 * are looking up the parent vnode - exactly reverse from
                 * normal operation.  Unlocking dvp requires some rather
                 * tricky unlock/relock dance to prevent mp from being freed;
                 * use vn_vget_ino_gen() which takes care of all that.
                 *
                 * XXX Note that there is a time window when both vnodes are
                 * unlocked.  It is possible, although highly unlikely, that
                 * during that window the parent-child relationship between
                 * the vnodes may change, for example, get reversed.
                 * In that case we would have a wrong lock order for the vnodes.
                 * All other filesystems seem to ignore this problem, so we
                 * do the same here.
                 * A potential solution could be implemented as follows:
                 * - using LK_NOWAIT when locking the second vnode and retrying
                 *   if necessary
                 * - checking that the parent-child relationship still holds
                 *   after locking both vnodes and retrying if it doesn't
                 */
                error = vn_vget_ino_gen(dvp, zfs_dd_callback, vp, lkflags, &vp);
                return (error);
        } else {
                error = vn_lock(vp, lkflags);
                if (error != 0)
                        vrele(vp);
                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
 *
 *      OUT:    vpp     - vnode of located entry, NULL if not found.
 *
 *      RETURN: 0 on success, error code on 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);
        znode_t *zp;
        zfsvfs_t *zfsvfs = zdp->z_zfsvfs;
        int     error = 0;

        /*
         * Fast path lookup, however we must skip DNLC lookup
         * for case folding or normalizing lookups because the
         * DNLC code only stores the passed in name.  This means
         * creating 'a' and removing 'A' on a case insensitive
         * file system would work, but DNLC still thinks 'a'
         * exists and won't let you create it again on the next
         * pass through fast path.
         */
        if (!(flags & LOOKUP_XATTR)) {
                if (dvp->v_type != VDIR) {
                        return (SET_ERROR(ENOTDIR));
                } else if (zdp->z_sa_hdl == NULL) {
                        return (SET_ERROR(EIO));
                }
        }

        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 (SET_ERROR(EINVAL));
                }
#endif

                /*
                 * We don't allow recursive attributes..
                 * Maybe someday we will.
                 */
                if (zdp->z_pflags & ZFS_XATTR) {
                        ZFS_EXIT(zfsvfs);
                        return (SET_ERROR(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)) {
                        vrele(*vpp);
                        *vpp = NULL;
                }

                ZFS_EXIT(zfsvfs);
                return (error);
        }

        /*
         * 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 (SET_ERROR(EILSEQ));
        }


        /*
         * First handle the special cases.
         */
        if ((cnp->cn_flags & ISDOTDOT) != 0) {
                /*
                 * If we are a snapshot mounted under .zfs, return
                 * the vp for the snapshot directory.
                 */
                if (zdp->z_id == zfsvfs->z_root && zfsvfs->z_parent != zfsvfs) {
                        struct componentname cn;
                        vnode_t *zfsctl_vp;
                        int ltype;

                        ZFS_EXIT(zfsvfs);
                        ltype = VOP_ISLOCKED(dvp);
                        VOP_UNLOCK(dvp, 0);
                        error = zfsctl_root(zfsvfs->z_parent, LK_SHARED,
                            &zfsctl_vp);
                        if (error == 0) {
                                cn.cn_nameptr = "snapshot";
                                cn.cn_namelen = strlen(cn.cn_nameptr);
                                cn.cn_nameiop = cnp->cn_nameiop;
                                cn.cn_flags = cnp->cn_flags & ~ISDOTDOT;
                                cn.cn_lkflags = cnp->cn_lkflags;
                                error = VOP_LOOKUP(zfsctl_vp, vpp, &cn);
                                vput(zfsctl_vp);
                        }
                        vn_lock(dvp, ltype | LK_RETRY);
                        return (error);
                }
        }
        if (zfs_has_ctldir(zdp) && strcmp(nm, ZFS_CTLDIR_NAME) == 0) {
                ZFS_EXIT(zfsvfs);
                if ((cnp->cn_flags & ISLASTCN) != 0 && nameiop != LOOKUP)
                        return (SET_ERROR(ENOTSUP));
                error = zfsctl_root(zfsvfs, cnp->cn_lkflags, vpp);
                return (error);
        }

        /*
         * The loop is retry the lookup if the parent-child relationship
         * changes during the dot-dot locking complexities.
         */
        for (;;) {
                uint64_t parent;

                error = zfs_dirlook(zdp, nm, &zp);
                if (error == 0)
                        *vpp = ZTOV(zp);

                ZFS_EXIT(zfsvfs);
                if (error != 0)
                        break;

                error = zfs_lookup_lock(dvp, *vpp, nm, cnp->cn_lkflags);
                if (error != 0) {
                        /*
                         * If we've got a locking error, then the vnode
                         * got reclaimed because of a force unmount.
                         * We never enter doomed vnodes into the name cache.
                         */
                        *vpp = NULL;
                        return (error);
                }

                if ((cnp->cn_flags & ISDOTDOT) == 0)
                        break;

                ZFS_ENTER(zfsvfs);
                if (zdp->z_sa_hdl == NULL) {
                        error = SET_ERROR(EIO);
                } else {
                        error = sa_lookup(zdp->z_sa_hdl, SA_ZPL_PARENT(zfsvfs),
                            &parent, sizeof (parent));
                }
                if (error != 0) {
                        ZFS_EXIT(zfsvfs);
                        vput(ZTOV(zp));
                        break;
                }
                if (zp->z_id == parent) {
                        ZFS_EXIT(zfsvfs);
                        break;
                }
                vput(ZTOV(zp));
        }

out:
        if (error != 0)
                *vpp = NULL;

        /* 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;
                }
        }

        /* Insert name into cache (as non-existent) if appropriate. */
        if (zfsvfs->z_use_namecache &&
            error == ENOENT && (cnp->cn_flags & MAKEENTRY) != 0)
                cache_enter(dvp, NULL, cnp);

        /* Insert name into cache if appropriate. */
        if (zfsvfs->z_use_namecache &&
            error == 0 && (cnp->cn_flags & MAKEENTRY)) {
                if (!(cnp->cn_flags & ISLASTCN) ||
                    (nameiop != DELETE && nameiop != RENAME)) {
                        cache_enter(dvp, *vpp, cnp);
                }
        }

        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 on success, error code on 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;
        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;
        uint64_t        txtype;

        /*
         * 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(uid) || IS_EPHEMERAL(gid)))
                return (SET_ERROR(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 (SET_ERROR(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);
                }
        }

        *vpp = NULL;

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

        error = zfs_dirent_lookup(dzp, name, &zp, ZNEW);
        if (error) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }
        ASSERT3P(zp, ==, NULL);

        /*
         * 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_pflags & ZFS_XATTR) &&
            (vap->va_type != VREG)) {
                error = SET_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 = SET_ERROR(EDQUOT);
                goto out;
        }

        getnewvnode_reserve(1);

        tx = dmu_tx_create(os);

        dmu_tx_hold_sa_create(tx, acl_ids.z_aclp->z_acl_bytes +
            ZFS_SA_BASE_ATTR_SIZE);

        fuid_dirtied = zfsvfs->z_fuid_dirty;
        if (fuid_dirtied)
                zfs_fuid_txhold(zfsvfs, tx);
        dmu_tx_hold_zap(tx, dzp->z_id, TRUE, name);
        dmu_tx_hold_sa(tx, dzp->z_sa_hdl, B_FALSE);
        if (!zfsvfs->z_use_sa &&
            acl_ids.z_aclp->z_acl_bytes > ZFS_ACE_SPACE) {
                dmu_tx_hold_write(tx, DMU_NEW_OBJECT,
                    0, acl_ids.z_aclp->z_acl_bytes);
        }
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                zfs_acl_ids_free(&acl_ids);
                dmu_tx_abort(tx);
                getnewvnode_drop_reserve();
                ZFS_EXIT(zfsvfs);
                return (error);
        }
        zfs_mknode(dzp, vap, tx, cr, 0, &zp, &acl_ids);

        if (fuid_dirtied)
                zfs_fuid_sync(zfsvfs, tx);

        (void) zfs_link_create(dzp, name, zp, tx, ZNEW);
        txtype = zfs_log_create_txtype(Z_FILE, vsecp, vap);
        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);

        getnewvnode_drop_reserve();

out:
        if (error == 0) {
                *vpp = ZTOV(zp);
        }

        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        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 on success, error code on failure.
 *
 * Timestamps:
 *      dvp - ctime|mtime
 *       vp - ctime (if nlink > 0)
 */

/*ARGSUSED*/
static int
zfs_remove(vnode_t *dvp, vnode_t *vp, char *name, cred_t *cr)
{
        znode_t         *dzp = VTOZ(dvp);
        znode_t         *zp = VTOZ(vp);
        znode_t         *xzp;
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        zilog_t         *zilog;
        uint64_t        acl_obj, xattr_obj;
        uint64_t        obj = 0;
        dmu_tx_t        *tx;
        boolean_t       unlinked, toobig = FALSE;
        uint64_t        txtype;
        int             error;

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

        xattr_obj = 0;
        xzp = NULL;

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

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

        vnevent_remove(vp, dvp, name, ct);

        obj = zp->z_id;

        /* are there any extended attributes? */
        error = sa_lookup(zp->z_sa_hdl, SA_ZPL_XATTR(zfsvfs),
            &xattr_obj, sizeof (xattr_obj));
        if (error == 0 && xattr_obj) {
                error = zfs_zget(zfsvfs, xattr_obj, &xzp);
                ASSERT0(error);
        }

        /*
         * 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_sa(tx, zp->z_sa_hdl, B_FALSE);
        zfs_sa_upgrade_txholds(tx, zp);
        zfs_sa_upgrade_txholds(tx, dzp);

        if (xzp) {
                dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_TRUE);
                dmu_tx_hold_sa(tx, xzp->z_sa_hdl, B_FALSE);
        }

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

        /*
         * Mark this transaction as typically resulting in a net free of space
         */
        dmu_tx_mark_netfree(tx);

        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        /*
         * Remove the directory entry.
         */
        error = zfs_link_destroy(dzp, name, zp, tx, ZEXISTS, &unlinked);

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

        if (unlinked) {
                zfs_unlinked_add(zp, tx);
                vp->v_vflag |= VV_NOSYNC;
        }

        txtype = TX_REMOVE;
        zfs_log_remove(zilog, tx, txtype, dzp, name, obj);

        dmu_tx_commit(tx);
out:

        if (xzp)
                vrele(ZTOV(xzp));

        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        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
 *              flags   - case flags
 *              vsecp   - ACL to be set
 *
 *      OUT:    vpp     - vnode of created directory.
 *
 *      RETURN: 0 on success, error code on 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)
{
        znode_t         *zp, *dzp = VTOZ(dvp);
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        zilog_t         *zilog;
        uint64_t        txtype;
        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;

        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 &&
            ((vap->va_mask & AT_XVATTR) ||
            IS_EPHEMERAL(uid) || IS_EPHEMERAL(gid)))
                return (SET_ERROR(EINVAL));

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

        if (dzp->z_pflags & ZFS_XATTR) {
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EINVAL));
        }

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

        if ((error = zfs_acl_ids_create(dzp, 0, vap, cr,
            NULL, &acl_ids)) != 0) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        /*
         * First make sure the new directory doesn't exist.
         *
         * Existence is checked first to make sure we don't return
         * EACCES instead of EEXIST which can cause some applications
         * to fail.
         */
        *vpp = NULL;

        if (error = zfs_dirent_lookup(dzp, dirname, &zp, ZNEW)) {
                zfs_acl_ids_free(&acl_ids);
                ZFS_EXIT(zfsvfs);
                return (error);
        }
        ASSERT3P(zp, ==, NULL);

        if (error = zfs_zaccess(dzp, ACE_ADD_SUBDIRECTORY, 0, B_FALSE, cr)) {
                zfs_acl_ids_free(&acl_ids);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        if (zfs_acl_ids_overquota(zfsvfs, &acl_ids)) {
                zfs_acl_ids_free(&acl_ids);
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EDQUOT));
        }

        /*
         * Add a new entry to the directory.
         */
        getnewvnode_reserve(1);
        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 (!zfsvfs->z_use_sa && acl_ids.z_aclp->z_acl_bytes > ZFS_ACE_SPACE) {
                dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0,
                    acl_ids.z_aclp->z_acl_bytes);
        }

        dmu_tx_hold_sa_create(tx, acl_ids.z_aclp->z_acl_bytes +
            ZFS_SA_BASE_ATTR_SIZE);

        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                zfs_acl_ids_free(&acl_ids);
                dmu_tx_abort(tx);
                getnewvnode_drop_reserve();
                ZFS_EXIT(zfsvfs);
                return (error);
        }

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

        if (fuid_dirtied)
                zfs_fuid_sync(zfsvfs, tx);

        /*
         * Now put new name in parent dir.
         */
        (void) zfs_link_create(dzp, dirname, zp, tx, ZNEW);

        *vpp = ZTOV(zp);

        txtype = zfs_log_create_txtype(Z_DIR, NULL, vap);
        zfs_log_create(zilog, tx, txtype, dzp, zp, dirname, NULL,
            acl_ids.z_fuidp, vap);

        zfs_acl_ids_free(&acl_ids);

        dmu_tx_commit(tx);

        getnewvnode_drop_reserve();

        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        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 on success, error code on failure.
 *
 * Timestamps:
 *      dvp - ctime|mtime updated
 */
/*ARGSUSED*/
static int
zfs_rmdir(vnode_t *dvp, vnode_t *vp, char *name, cred_t *cr)
{
        znode_t         *dzp = VTOZ(dvp);
        znode_t         *zp = VTOZ(vp);
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        zilog_t         *zilog;
        dmu_tx_t        *tx;
        int             error;

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


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

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

        vnevent_rmdir(vp, dvp, name, ct);

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_zap(tx, dzp->z_id, FALSE, name);
        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
        dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
        zfs_sa_upgrade_txholds(tx, zp);
        zfs_sa_upgrade_txholds(tx, dzp);
        dmu_tx_mark_netfree(tx);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        cache_purge(dvp);

        error = zfs_link_destroy(dzp, name, zp, tx, ZEXISTS, NULL);

        if (error == 0) {
                uint64_t txtype = TX_RMDIR;
                zfs_log_remove(zilog, tx, txtype, dzp, name, ZFS_NO_OBJECT);
        }

        dmu_tx_commit(tx);

        cache_purge(vp);
out:
        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        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 on success, error code on 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 */
        uint64_t        parent;
        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 ((error = sa_lookup(zp->z_sa_hdl, SA_ZPL_PARENT(zfsvfs),
            &parent, sizeof (parent))) != 0) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        /*
         * 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 (SET_ERROR(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;
                outbuf = NULL;
                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 = NULL;

                /*
                 * 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 = 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 = SET_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)) {
                                vrele(ZTOV(ezp));
                                goto skip_entry;
                        }
                        vrele(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 = SET_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);
                        /* NOTE: d_off is the offset for the *next* entry. */
                        next = &odp->d_off;
                        (void) strlcpy(odp->d_name, zap.za_name, odp->d_namlen + 1);
                        odp->d_type = type;
                        dirent_terminate(odp);
                        odp = (dirent64_t *)((intptr_t)odp + reclen);
                }
                outcount += reclen;

                ASSERT(outcount <= bufsize);

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

        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;
                }

                /* Fill the offset right after advancing the cursor. */
                if (next != NULL)
                        *next = offset;
                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);

        if (zfsvfs->z_os->os_sync != ZFS_SYNC_DISABLED) {
                ZFS_ENTER(zfsvfs);
                ZFS_VERIFY_ZP(zp);
                zil_commit(zfsvfs->z_log, 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;
        int     error = 0;
        uint32_t blksize;
        u_longlong_t nblocks;
        uint64_t mtime[2], ctime[2], crtime[2], rdev;
        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;
        sa_bulk_attr_t bulk[4];
        int count = 0;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        zfs_fuid_map_ids(zp, cr, &vap->va_uid, &vap->va_gid);

        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs), NULL, &mtime, 16);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL, &ctime, 16);
        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CRTIME(zfsvfs), NULL, &crtime, 16);
        if (vp->v_type == VBLK || vp->v_type == VCHR)
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_RDEV(zfsvfs), NULL,
                    &rdev, 8);

        if ((error = sa_bulk_lookup(zp->z_sa_hdl, bulk, count)) != 0) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        /*
         * 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 (!(zp->z_pflags & ZFS_ACL_TRIVIAL) &&
            (vap->va_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.
         */

        vap->va_type = IFTOVT(zp->z_mode);
        vap->va_mode = zp->z_mode & ~S_IFMT;
#ifdef illumos
        vap->va_fsid = zp->z_zfsvfs->z_vfs->vfs_dev;
#else
        vn_fsid(vp, vap);
#endif
        vap->va_nodeid = zp->z_id;
        vap->va_nlink = zp->z_links;
        if ((vp->v_flag & VROOT) && zfs_show_ctldir(zp) &&
            zp->z_links < ZFS_LINK_MAX)
                vap->va_nlink++;
        vap->va_size = zp->z_size;
#ifdef illumos
        vap->va_rdev = vp->v_rdev;
#else
        if (vp->v_type == VBLK || vp->v_type == VCHR)
                vap->va_rdev = zfs_cmpldev(rdev);
#endif
        vap->va_seq = zp->z_seq;
        vap->va_flags = 0;      /* FreeBSD: Reset chflags(2) flags. */
        vap->va_filerev = zp->z_seq;

        /*
         * 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 =
                            ((zp->z_pflags & ZFS_ARCHIVE) != 0);
                        XVA_SET_RTN(xvap, XAT_ARCHIVE);
                }

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

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

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

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

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

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

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

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

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

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

                if (XVA_ISSET_REQ(xvap, XAT_AV_SCANSTAMP) &&
                    vp->v_type == VREG) {
                        zfs_sa_get_scanstamp(zp, xvap);
                }

                if (XVA_ISSET_REQ(xvap, XAT_REPARSE)) {
                        xoap->xoa_reparse = ((zp->z_pflags & ZFS_REPARSE) != 0);
                        XVA_SET_RTN(xvap, XAT_REPARSE);
                }
                if (XVA_ISSET_REQ(xvap, XAT_GEN)) {
                        xoap->xoa_generation = zp->z_gen;
                        XVA_SET_RTN(xvap, XAT_GEN);
                }

                if (XVA_ISSET_REQ(xvap, XAT_OFFLINE)) {
                        xoap->xoa_offline =
                            ((zp->z_pflags & ZFS_OFFLINE) != 0);
                        XVA_SET_RTN(xvap, XAT_OFFLINE);
                }

                if (XVA_ISSET_REQ(xvap, XAT_SPARSE)) {
                        xoap->xoa_sparse =
                            ((zp->z_pflags & ZFS_SPARSE) != 0);
                        XVA_SET_RTN(xvap, XAT_SPARSE);
                }
        }

        ZFS_TIME_DECODE(&vap->va_atime, zp->z_atime);
        ZFS_TIME_DECODE(&vap->va_mtime, mtime);
        ZFS_TIME_DECODE(&vap->va_ctime, ctime);
        ZFS_TIME_DECODE(&vap->va_birthtime, crtime);


        sa_object_size(zp->z_sa_hdl, &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 on success, error code on 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);
        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 = 0;
        uint64_t        saved_mode;
        int             trim_mask = 0;
        uint64_t        new_mode;
        uint64_t        new_uid, new_gid;
        uint64_t        xattr_obj;
        uint64_t        mtime[2], ctime[2];
        znode_t         *attrzp;
        int             need_policy = FALSE;
        int             err, err2;
        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;
        boolean_t skipaclchk = (flags & ATTR_NOACLCHECK) ? B_TRUE : B_FALSE;
        boolean_t       fuid_dirtied = B_FALSE;
        sa_bulk_attr_t  bulk[7], xattr_bulk[7];
        int             count = 0, xattr_count = 0;

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

        if (mask & AT_NOSET)
                return (SET_ERROR(EINVAL));

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        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 (SET_ERROR(EINVAL));
        }

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

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

        /*
         * Note: ZFS_READONLY is handled in zfs_zaccess_common.
         */

        /*
         * 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 (SET_ERROR(EOVERFLOW));
                }
        }
        if (xoap && (mask & AT_XVATTR) && XVA_ISSET_REQ(xvap, XAT_CREATETIME) &&
            TIMESPEC_OVERFLOW(&vap->va_birthtime)) {
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EOVERFLOW));
        }

        attrzp = NULL;
        aclp = NULL;

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

        /*
         * First validate permissions
         */

        if (mask & AT_SIZE) {
                /*
                 * 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_OFFLINE) ||
            XVA_ISSET_REQ(xvap, XAT_SPARSE) ||
            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 = zp->z_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;
                }
        }

        oldva.va_mode = zp->z_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 !=
                            ((zp->z_pflags & 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 !=
                            ((zp->z_pflags & 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 !=
                            ((zp->z_pflags & 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 !=
                            ((zp->z_pflags & 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 !=
                            ((zp->z_pflags & 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 !=
                            ((zp->z_pflags & ZFS_AV_QUARANTINED) != 0)) {
                                need_policy = TRUE;
                        } else {
                                XVA_CLR_REQ(xvap, XAT_AV_QUARANTINED);
                                XVA_SET_REQ(&tmpxvattr, XAT_AV_QUARANTINED);
                        }
                }

                if (XVA_ISSET_REQ(xvap, XAT_REPARSE)) {
                        ZFS_EXIT(zfsvfs);
                        return (SET_ERROR(EPERM));
                }

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

        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;

        if ((mask & (AT_UID | AT_GID))) {
                err = sa_lookup(zp->z_sa_hdl, SA_ZPL_XATTR(zfsvfs),
                    &xattr_obj, sizeof (xattr_obj));

                if (err == 0 && xattr_obj) {
                        err = zfs_zget(zp->z_zfsvfs, xattr_obj, &attrzp);
                        if (err == 0) {
                                err = vn_lock(ZTOV(attrzp), LK_EXCLUSIVE);
                                if (err != 0)
                                        vrele(ZTOV(attrzp));
                        }
                        if (err)
                                goto out2;
                }
                if (mask & AT_UID) {
                        new_uid = zfs_fuid_create(zfsvfs,
                            (uint64_t)vap->va_uid, cr, ZFS_OWNER, &fuidp);
                        if (new_uid != zp->z_uid &&
                            zfs_fuid_overquota(zfsvfs, B_FALSE, new_uid)) {
                                if (attrzp)
                                        vput(ZTOV(attrzp));
                                err = SET_ERROR(EDQUOT);
                                goto out2;
                        }
                }

                if (mask & AT_GID) {
                        new_gid = zfs_fuid_create(zfsvfs, (uint64_t)vap->va_gid,
                            cr, ZFS_GROUP, &fuidp);
                        if (new_gid != zp->z_gid &&
                            zfs_fuid_overquota(zfsvfs, B_TRUE, new_gid)) {
                                if (attrzp)
                                        vput(ZTOV(attrzp));
                                err = SET_ERROR(EDQUOT);
                                goto out2;
                        }
                }
        }
        tx = dmu_tx_create(zfsvfs->z_os);

        if (mask & AT_MODE) {
                uint64_t pmode = zp->z_mode;
                uint64_t acl_obj;
                new_mode = (pmode & S_IFMT) | (vap->va_mode & ~S_IFMT);

                if (zp->z_zfsvfs->z_acl_mode == ZFS_ACL_RESTRICTED &&
                    !(zp->z_pflags & ZFS_ACL_TRIVIAL)) {
                        err = SET_ERROR(EPERM);
                        goto out;
                }

                if (err = zfs_acl_chmod_setattr(zp, &aclp, new_mode))
                        goto out;

                if (!zp->z_is_sa && ((acl_obj = zfs_external_acl(zp)) != 0)) {
                        /*
                         * Are we upgrading ACL from old V0 format
                         * to V1 format?
                         */
                        if (zfsvfs->z_version >= ZPL_VERSION_FUID &&
                            zfs_znode_acl_version(zp) ==
                            ZFS_ACL_VERSION_INITIAL) {
                                dmu_tx_hold_free(tx, acl_obj, 0,
                                    DMU_OBJECT_END);
                                dmu_tx_hold_write(tx, DMU_NEW_OBJECT,
                                    0, aclp->z_acl_bytes);
                        } else {
                                dmu_tx_hold_write(tx, acl_obj, 0,
                                    aclp->z_acl_bytes);
                        }
                } else if (!zp->z_is_sa && aclp->z_acl_bytes > ZFS_ACE_SPACE) {
                        dmu_tx_hold_write(tx, DMU_NEW_OBJECT,
                            0, aclp->z_acl_bytes);
                }
                dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_TRUE);
        } else {
                if ((mask & AT_XVATTR) &&
                    XVA_ISSET_REQ(xvap, XAT_AV_SCANSTAMP))
                        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_TRUE);
                else
                        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
        }

        if (attrzp) {
                dmu_tx_hold_sa(tx, attrzp->z_sa_hdl, B_FALSE);
        }

        fuid_dirtied = zfsvfs->z_fuid_dirty;
        if (fuid_dirtied)
                zfs_fuid_txhold(zfsvfs, tx);

        zfs_sa_upgrade_txholds(tx, zp);

        err = dmu_tx_assign(tx, TXG_WAIT);
        if (err)
                goto out;

        count = 0;
        /*
         * 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.
         */

        if (mask & (AT_UID|AT_GID|AT_MODE))
                mutex_enter(&zp->z_acl_lock);

        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs), NULL,
            &zp->z_pflags, sizeof (zp->z_pflags));

        if (attrzp) {
                if (mask & (AT_UID|AT_GID|AT_MODE))
                        mutex_enter(&attrzp->z_acl_lock);
                SA_ADD_BULK_ATTR(xattr_bulk, xattr_count,
                    SA_ZPL_FLAGS(zfsvfs), NULL, &attrzp->z_pflags,
                    sizeof (attrzp->z_pflags));
        }

        if (mask & (AT_UID|AT_GID)) {

                if (mask & AT_UID) {
                        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_UID(zfsvfs), NULL,
                            &new_uid, sizeof (new_uid));
                        zp->z_uid = new_uid;
                        if (attrzp) {
                                SA_ADD_BULK_ATTR(xattr_bulk, xattr_count,
                                    SA_ZPL_UID(zfsvfs), NULL, &new_uid,
                                    sizeof (new_uid));
                                attrzp->z_uid = new_uid;
                        }
                }

                if (mask & AT_GID) {
                        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_GID(zfsvfs),
                            NULL, &new_gid, sizeof (new_gid));
                        zp->z_gid = new_gid;
                        if (attrzp) {
                                SA_ADD_BULK_ATTR(xattr_bulk, xattr_count,
                                    SA_ZPL_GID(zfsvfs), NULL, &new_gid,
                                    sizeof (new_gid));
                                attrzp->z_gid = new_gid;
                        }
                }
                if (!(mask & AT_MODE)) {
                        SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MODE(zfsvfs),
                            NULL, &new_mode, sizeof (new_mode));
                        new_mode = zp->z_mode;
                }
                err = zfs_acl_chown_setattr(zp);
                ASSERT(err == 0);
                if (attrzp) {
                        err = zfs_acl_chown_setattr(attrzp);
                        ASSERT(err == 0);
                }
        }

        if (mask & AT_MODE) {
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MODE(zfsvfs), NULL,
                    &new_mode, sizeof (new_mode));
                zp->z_mode = new_mode;
                ASSERT3U((uintptr_t)aclp, !=, 0);
                err = zfs_aclset_common(zp, aclp, cr, tx);
                ASSERT0(err);
                if (zp->z_acl_cached)
                        zfs_acl_free(zp->z_acl_cached);
                zp->z_acl_cached = aclp;
                aclp = NULL;
        }


        if (mask & AT_ATIME) {
                ZFS_TIME_ENCODE(&vap->va_atime, zp->z_atime);
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_ATIME(zfsvfs), NULL,
                    &zp->z_atime, sizeof (zp->z_atime));
        }

        if (mask & AT_MTIME) {
                ZFS_TIME_ENCODE(&vap->va_mtime, mtime);
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs), NULL,
                    mtime, sizeof (mtime));
        }

        /* XXX - shouldn't this be done *before* the ATIME/MTIME checks? */
        if (mask & AT_SIZE && !(mask & AT_MTIME)) {
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs),
                    NULL, mtime, sizeof (mtime));
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL,
                    &ctime, sizeof (ctime));
                zfs_tstamp_update_setup(zp, CONTENT_MODIFIED, mtime, ctime,
                    B_TRUE);
        } else if (mask != 0) {
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL,
                    &ctime, sizeof (ctime));
                zfs_tstamp_update_setup(zp, STATE_CHANGED, mtime, ctime,
                    B_TRUE);
                if (attrzp) {
                        SA_ADD_BULK_ATTR(xattr_bulk, xattr_count,
                            SA_ZPL_CTIME(zfsvfs), NULL,
                            &ctime, sizeof (ctime));
                        zfs_tstamp_update_setup(attrzp, STATE_CHANGED,
                            mtime, ctime, B_TRUE);
                }
        }
        /*
         * Do this after setting timestamps to prevent timestamp
         * update from toggling bit
         */

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

                if (XVA_ISSET_REQ(xvap, XAT_CREATETIME))
                        xoap->xoa_createtime = vap->va_birthtime;
                /*
                 * 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))
                        ASSERT(vp->v_type == VREG);

                zfs_xvattr_set(zp, xvap, tx);
        }

        if (fuid_dirtied)
                zfs_fuid_sync(zfsvfs, tx);

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

        if (mask & (AT_UID|AT_GID|AT_MODE))
                mutex_exit(&zp->z_acl_lock);

        if (attrzp) {
                if (mask & (AT_UID|AT_GID|AT_MODE))
                        mutex_exit(&attrzp->z_acl_lock);
        }
out:
        if (err == 0 && attrzp) {
                err2 = sa_bulk_update(attrzp->z_sa_hdl, xattr_bulk,
                    xattr_count, tx);
                ASSERT(err2 == 0);
        }

        if (attrzp)
                vput(ZTOV(attrzp));

        if (aclp)
                zfs_acl_free(aclp);

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

        if (err) {
                dmu_tx_abort(tx);
        } else {
                err2 = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
                dmu_tx_commit(tx);
        }

out2:
        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        ZFS_EXIT(zfsvfs);
        return (err);
}

/*
 * We acquire all but fdvp locks using non-blocking acquisitions.  If we
 * fail to acquire any lock in the path we will drop all held locks,
 * acquire the new lock in a blocking fashion, and then release it and
 * restart the rename.  This acquire/release step ensures that we do not
 * spin on a lock waiting for release.  On error release all vnode locks
 * and decrement references the way tmpfs_rename() would do.
 */
static int
zfs_rename_relock(struct vnode *sdvp, struct vnode **svpp,
    struct vnode *tdvp, struct vnode **tvpp,
    const struct componentname *scnp, const struct componentname *tcnp)
{
        zfsvfs_t        *zfsvfs;
        struct vnode    *nvp, *svp, *tvp;
        znode_t         *sdzp, *tdzp, *szp, *tzp;
        const char      *snm = scnp->cn_nameptr;
        const char      *tnm = tcnp->cn_nameptr;
        int error;

        VOP_UNLOCK(tdvp, 0);
        if (*tvpp != NULL && *tvpp != tdvp)
                VOP_UNLOCK(*tvpp, 0);

relock:
        error = vn_lock(sdvp, LK_EXCLUSIVE);
        if (error)
                goto out;
        sdzp = VTOZ(sdvp);

        error = vn_lock(tdvp, LK_EXCLUSIVE | LK_NOWAIT);
        if (error != 0) {
                VOP_UNLOCK(sdvp, 0);
                if (error != EBUSY)
                        goto out;
                error = vn_lock(tdvp, LK_EXCLUSIVE);
                if (error)
                        goto out;
                VOP_UNLOCK(tdvp, 0);
                goto relock;
        }
        tdzp = VTOZ(tdvp);

        /*
         * Before using sdzp and tdzp we must ensure that they are live.
         * As a porting legacy from illumos we have two things to worry
         * about.  One is typical for FreeBSD and it is that the vnode is
         * not reclaimed (doomed).  The other is that the znode is live.
         * The current code can invalidate the znode without acquiring the
         * corresponding vnode lock if the object represented by the znode
         * and vnode is no longer valid after a rollback or receive operation.
         * z_teardown_lock hidden behind ZFS_ENTER and ZFS_EXIT is the lock
         * that protects the znodes from the invalidation.
         */
        zfsvfs = sdzp->z_zfsvfs;
        ASSERT3P(zfsvfs, ==, tdzp->z_zfsvfs);
        ZFS_ENTER(zfsvfs);

        /*
         * We can not use ZFS_VERIFY_ZP() here because it could directly return
         * bypassing the cleanup code in the case of an error.
         */
        if (tdzp->z_sa_hdl == NULL || sdzp->z_sa_hdl == NULL) {
                ZFS_EXIT(zfsvfs);
                VOP_UNLOCK(sdvp, 0);
                VOP_UNLOCK(tdvp, 0);
                error = SET_ERROR(EIO);
                goto out;
        }

        /*
         * Re-resolve svp to be certain it still exists and fetch the
         * correct vnode.
         */
        error = zfs_dirent_lookup(sdzp, snm, &szp, ZEXISTS);
        if (error != 0) {
                /* Source entry invalid or not there. */
                ZFS_EXIT(zfsvfs);
                VOP_UNLOCK(sdvp, 0);
                VOP_UNLOCK(tdvp, 0);
                if ((scnp->cn_flags & ISDOTDOT) != 0 ||
                    (scnp->cn_namelen == 1 && scnp->cn_nameptr[0] == '.'))
                        error = SET_ERROR(EINVAL);
                goto out;
        }
        svp = ZTOV(szp);

        /*
         * Re-resolve tvp, if it disappeared we just carry on.
         */
        error = zfs_dirent_lookup(tdzp, tnm, &tzp, 0);
        if (error != 0) {
                ZFS_EXIT(zfsvfs);
                VOP_UNLOCK(sdvp, 0);
                VOP_UNLOCK(tdvp, 0);
                vrele(svp);
                if ((tcnp->cn_flags & ISDOTDOT) != 0)
                        error = SET_ERROR(EINVAL);
                goto out;
        }
        if (tzp != NULL)
                tvp = ZTOV(tzp);
        else
                tvp = NULL;

        /*
         * At present the vnode locks must be acquired before z_teardown_lock,
         * although it would be more logical to use the opposite order.
         */
        ZFS_EXIT(zfsvfs);

        /*
         * Now try acquire locks on svp and tvp.
         */
        nvp = svp;
        error = vn_lock(nvp, LK_EXCLUSIVE | LK_NOWAIT);
        if (error != 0) {
                VOP_UNLOCK(sdvp, 0);
                VOP_UNLOCK(tdvp, 0);
                if (tvp != NULL)
                        vrele(tvp);
                if (error != EBUSY) {
                        vrele(nvp);
                        goto out;
                }
                error = vn_lock(nvp, LK_EXCLUSIVE);
                if (error != 0) {
                        vrele(nvp);
                        goto out;
                }
                VOP_UNLOCK(nvp, 0);
                /*
                 * Concurrent rename race.
                 * XXX ?
                 */
                if (nvp == tdvp) {
                        vrele(nvp);
                        error = SET_ERROR(EINVAL);
                        goto out;
                }
                vrele(*svpp);
                *svpp = nvp;
                goto relock;
        }
        vrele(*svpp);
        *svpp = nvp;

        if (*tvpp != NULL)
                vrele(*tvpp);
        *tvpp = NULL;
        if (tvp != NULL) {
                nvp = tvp;
                error = vn_lock(nvp, LK_EXCLUSIVE | LK_NOWAIT);
                if (error != 0) {
                        VOP_UNLOCK(sdvp, 0);
                        VOP_UNLOCK(tdvp, 0);
                        VOP_UNLOCK(*svpp, 0);
                        if (error != EBUSY) {
                                vrele(nvp);
                                goto out;
                        }
                        error = vn_lock(nvp, LK_EXCLUSIVE);
                        if (error != 0) {
                                vrele(nvp);
                                goto out;
                        }
                        vput(nvp);
                        goto relock;
                }
                *tvpp = nvp;
        }

        return (0);

out:
        return (error);
}

/*
 * Note that we must use VRELE_ASYNC in this function as it walks
 * up the directory tree and vrele may need to acquire an exclusive
 * lock if a last reference to a vnode is dropped.
 */
static int
zfs_rename_check(znode_t *szp, znode_t *sdzp, znode_t *tdzp)
{
        zfsvfs_t        *zfsvfs;
        znode_t         *zp, *zp1;
        uint64_t        parent;
        int             error;

        zfsvfs = tdzp->z_zfsvfs;
        if (tdzp == szp)
                return (SET_ERROR(EINVAL));
        if (tdzp == sdzp)
                return (0);
        if (tdzp->z_id == zfsvfs->z_root)
                return (0);
        zp = tdzp;
        for (;;) {
                ASSERT(!zp->z_unlinked);
                if ((error = sa_lookup(zp->z_sa_hdl,
                    SA_ZPL_PARENT(zfsvfs), &parent, sizeof (parent))) != 0)
                        break;

                if (parent == szp->z_id) {
                        error = SET_ERROR(EINVAL);
                        break;
                }
                if (parent == zfsvfs->z_root)
                        break;
                if (parent == sdzp->z_id)
                        break;

                error = zfs_zget(zfsvfs, parent, &zp1);
                if (error != 0)
                        break;

                if (zp != tdzp)
                        VN_RELE_ASYNC(ZTOV(zp),
                            dsl_pool_vnrele_taskq(dmu_objset_pool(zfsvfs->z_os)));
                zp = zp1;
        }

        if (error == ENOTDIR)
                panic("checkpath: .. not a directory\n");
        if (zp != tdzp)
                VN_RELE_ASYNC(ZTOV(zp),
                    dsl_pool_vnrele_taskq(dmu_objset_pool(zfsvfs->z_os)));
        return (error);
}

/*
 * 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 on success, error code on failure.
 *
 * Timestamps:
 *      sdvp,tdvp - ctime|mtime updated
 */
/*ARGSUSED*/
static int
zfs_rename(vnode_t *sdvp, vnode_t **svpp, struct componentname *scnp,
    vnode_t *tdvp, vnode_t **tvpp, struct componentname *tcnp,
    cred_t *cr)
{
        zfsvfs_t        *zfsvfs;
        znode_t         *sdzp, *tdzp, *szp, *tzp;
        zilog_t         *zilog = NULL;
        dmu_tx_t        *tx;
        char            *snm = scnp->cn_nameptr;
        char            *tnm = tcnp->cn_nameptr;
        int             error = 0;

        /* Reject renames across filesystems. */
        if ((*svpp)->v_mount != tdvp->v_mount ||
            ((*tvpp) != NULL && (*svpp)->v_mount != (*tvpp)->v_mount)) {
                error = SET_ERROR(EXDEV);
                goto out;
        }

        if (zfsctl_is_node(tdvp)) {
                error = SET_ERROR(EXDEV);
                goto out;
        }

        /*
         * Lock all four vnodes to ensure safety and semantics of renaming.
         */
        error = zfs_rename_relock(sdvp, svpp, tdvp, tvpp, scnp, tcnp);
        if (error != 0) {
                /* no vnodes are locked in the case of error here */
                return (error);
        }

        tdzp = VTOZ(tdvp);
        sdzp = VTOZ(sdvp);
        zfsvfs = tdzp->z_zfsvfs;
        zilog = zfsvfs->z_log;

        /*
         * After we re-enter ZFS_ENTER() we will have to revalidate all
         * znodes involved.
         */
        ZFS_ENTER(zfsvfs);

        if (zfsvfs->z_utf8 && u8_validate(tnm,
            strlen(tnm), NULL, U8_VALIDATE_ENTIRE, &error) < 0) {
                error = SET_ERROR(EILSEQ);
                goto unlockout;
        }

        /* If source and target are the same file, there is nothing to do. */
        if ((*svpp) == (*tvpp)) {
                error = 0;
                goto unlockout;
        }

        if (((*svpp)->v_type == VDIR && (*svpp)->v_mountedhere != NULL) ||
            ((*tvpp) != NULL && (*tvpp)->v_type == VDIR &&
            (*tvpp)->v_mountedhere != NULL)) {
                error = SET_ERROR(EXDEV);
                goto unlockout;
        }

        /*
         * We can not use ZFS_VERIFY_ZP() here because it could directly return
         * bypassing the cleanup code in the case of an error.
         */
        if (tdzp->z_sa_hdl == NULL || sdzp->z_sa_hdl == NULL) {
                error = SET_ERROR(EIO);
                goto unlockout;
        }

        szp = VTOZ(*svpp);
        tzp = *tvpp == NULL ? NULL : VTOZ(*tvpp);
        if (szp->z_sa_hdl == NULL || (tzp != NULL && tzp->z_sa_hdl == NULL)) {
                error = SET_ERROR(EIO);
                goto unlockout;
        }

        /*
         * 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_pflags & ZFS_XATTR) != (sdzp->z_pflags & ZFS_XATTR)) {
                error = SET_ERROR(EINVAL);
                goto unlockout;
        }

        /*
         * 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 unlockout;

        if ((*svpp)->v_type == VDIR) {
                /*
                 * Avoid ".", "..", and aliases of "." for obvious reasons.
                 */
                if ((scnp->cn_namelen == 1 && scnp->cn_nameptr[0] == '.') ||
                    sdzp == szp ||
                    (scnp->cn_flags | tcnp->cn_flags) & ISDOTDOT) {
                        error = EINVAL;
                        goto unlockout;
                }

                /*
                 * 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_check(szp, sdzp, tdzp))
                        goto unlockout;
        }

        /*
         * Does target exist?
         */
        if (tzp) {
                /*
                 * Source and target must be the same type.
                 */
                if ((*svpp)->v_type == VDIR) {
                        if ((*tvpp)->v_type != VDIR) {
                                error = SET_ERROR(ENOTDIR);
                                goto unlockout;
                        } else {
                                cache_purge(tdvp);
                                if (sdvp != tdvp)
                                        cache_purge(sdvp);
                        }
                } else {
                        if ((*tvpp)->v_type == VDIR) {
                                error = SET_ERROR(EISDIR);
                                goto unlockout;
                        }
                }
        }

        vnevent_rename_src(*svpp, sdvp, scnp->cn_nameptr, ct);
        if (tzp)
                vnevent_rename_dest(*tvpp, 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_sa(tx, szp->z_sa_hdl, B_FALSE);
        dmu_tx_hold_sa(tx, sdzp->z_sa_hdl, B_FALSE);
        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_sa(tx, tdzp->z_sa_hdl, B_FALSE);
                zfs_sa_upgrade_txholds(tx, tdzp);
        }
        if (tzp) {
                dmu_tx_hold_sa(tx, tzp->z_sa_hdl, B_FALSE);
                zfs_sa_upgrade_txholds(tx, tzp);
        }

        zfs_sa_upgrade_txholds(tx, szp);
        dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                goto unlockout;
        }


        if (tzp)        /* Attempt to remove the existing target */
                error = zfs_link_destroy(tdzp, tnm, tzp, tx, 0, NULL);

        if (error == 0) {
                error = zfs_link_create(tdzp, tnm, szp, tx, ZRENAMING);
                if (error == 0) {
                        szp->z_pflags |= ZFS_AV_MODIFIED;

                        error = sa_update(szp->z_sa_hdl, SA_ZPL_FLAGS(zfsvfs),
                            (void *)&szp->z_pflags, sizeof (uint64_t), tx);
                        ASSERT0(error);

                        error = zfs_link_destroy(sdzp, snm, szp, tx, ZRENAMING,
                            NULL);
                        if (error == 0) {
                                zfs_log_rename(zilog, tx, TX_RENAME, sdzp,
                                    snm, tdzp, tnm, szp);

                                /*
                                 * Update path information for the target vnode
                                 */
                                vn_renamepath(tdvp, *svpp, tnm, strlen(tnm));
                        } else {
                                /*
                                 * At this point, we have successfully created
                                 * the target name, but have failed to remove
                                 * the source name.  Since the create was done
                                 * with the ZRENAMING flag, there are
                                 * complications; for one, the link count is
                                 * wrong.  The easiest way to deal with this
                                 * is to remove the newly created target, and
                                 * return the original error.  This must
                                 * succeed; fortunately, it is very unlikely to
                                 * fail, since we just created it.
                                 */
                                VERIFY3U(zfs_link_destroy(tdzp, tnm, szp, tx,
                                    ZRENAMING, NULL), ==, 0);
                        }
                }
                if (error == 0) {
                        cache_purge(*svpp);
                        if (*tvpp != NULL)
                                cache_purge(*tvpp);
                        cache_purge_negative(tdvp);
                }
        }

        dmu_tx_commit(tx);

unlockout:                      /* all 4 vnodes are locked, ZFS_ENTER called */
        ZFS_EXIT(zfsvfs);
        VOP_UNLOCK(*svpp, 0);
        VOP_UNLOCK(sdvp, 0);

out:                            /* original two vnodes are locked */
        if (error == 0 && zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        if (*tvpp != NULL)
                VOP_UNLOCK(*tvpp, 0);
        if (tdvp != *tvpp)
                VOP_UNLOCK(tdvp, 0);
        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.
 *              cr      - credentials of caller.
 *              ct      - caller context
 *              flags   - case flags
 *
 *      RETURN: 0 on success, error code on 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);
        dmu_tx_t        *tx;
        zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
        zilog_t         *zilog;
        uint64_t        len = strlen(link);
        int             error;
        zfs_acl_ids_t   acl_ids;
        boolean_t       fuid_dirtied;
        uint64_t        txtype = TX_SYMLINK;
        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 (SET_ERROR(EILSEQ));
        }

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

        if ((error = zfs_acl_ids_create(dzp, 0,
            vap, cr, NULL, &acl_ids)) != 0) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        /*
         * Attempt to lock directory; fail if entry already exists.
         */
        error = zfs_dirent_lookup(dzp, name, &zp, ZNEW);
        if (error) {
                zfs_acl_ids_free(&acl_ids);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

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

        if (zfs_acl_ids_overquota(zfsvfs, &acl_ids)) {
                zfs_acl_ids_free(&acl_ids);
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EDQUOT));
        }

        getnewvnode_reserve(1);
        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_zap(tx, dzp->z_id, TRUE, name);
        dmu_tx_hold_sa_create(tx, acl_ids.z_aclp->z_acl_bytes +
            ZFS_SA_BASE_ATTR_SIZE + len);
        dmu_tx_hold_sa(tx, dzp->z_sa_hdl, B_FALSE);
        if (!zfsvfs->z_use_sa && acl_ids.z_aclp->z_acl_bytes > ZFS_ACE_SPACE) {
                dmu_tx_hold_write(tx, DMU_NEW_OBJECT, 0,
                    acl_ids.z_aclp->z_acl_bytes);
        }
        if (fuid_dirtied)
                zfs_fuid_txhold(zfsvfs, tx);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                zfs_acl_ids_free(&acl_ids);
                dmu_tx_abort(tx);
                getnewvnode_drop_reserve();
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        /*
         * Create a new object for the symlink.
         * for version 4 ZPL datsets the symlink will be an SA attribute
         */
        zfs_mknode(dzp, vap, tx, cr, 0, &zp, &acl_ids);

        if (fuid_dirtied)
                zfs_fuid_sync(zfsvfs, tx);

        if (zp->z_is_sa)
                error = sa_update(zp->z_sa_hdl, SA_ZPL_SYMLINK(zfsvfs),
                    link, len, tx);
        else
                zfs_sa_symlink(zp, link, len, tx);

        zp->z_size = len;
        (void) sa_update(zp->z_sa_hdl, SA_ZPL_SIZE(zfsvfs),
            &zp->z_size, sizeof (zp->z_size), tx);
        /*
         * Insert the new object into the directory.
         */
        (void) zfs_link_create(dzp, name, zp, tx, ZNEW);

        zfs_log_symlink(zilog, tx, txtype, dzp, zp, name, link);
        *vpp = ZTOV(zp);

        zfs_acl_ids_free(&acl_ids);

        dmu_tx_commit(tx);

        getnewvnode_drop_reserve();

        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        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.
 *              uio     - structure to contain the link path.
 *              cr      - credentials of caller.
 *              ct      - caller context
 *
 *      OUT:    uio     - structure containing the link path.
 *
 *      RETURN: 0 on success, error code on 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;
        int             error;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        if (zp->z_is_sa)
                error = sa_lookup_uio(zp->z_sa_hdl,
                    SA_ZPL_SYMLINK(zfsvfs), uio);
        else
                error = zfs_sa_readlink(zp, uio);

        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 on success, error code on 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;
        dmu_tx_t        *tx;
        int             error;
        uint64_t        parent;
        uid_t           owner;

        ASSERT(tdvp->v_type == VDIR);

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

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

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

        if (szp->z_pflags & (ZFS_APPENDONLY | ZFS_IMMUTABLE | ZFS_READONLY)) {
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EPERM));
        }

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

        if ((error = sa_lookup(szp->z_sa_hdl, SA_ZPL_PARENT(zfsvfs),
            &parent, sizeof (uint64_t))) != 0) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }
        if (parent == zfsvfs->z_shares_dir) {
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EPERM));
        }

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

        /*
         * 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_pflags & ZFS_XATTR) != (dzp->z_pflags & ZFS_XATTR)) {
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(EINVAL));
        }


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

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

        /*
         * Attempt to lock directory; fail if entry already exists.
         */
        error = zfs_dirent_lookup(dzp, name, &tzp, ZNEW);
        if (error) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_sa(tx, szp->z_sa_hdl, B_FALSE);
        dmu_tx_hold_zap(tx, dzp->z_id, TRUE, name);
        zfs_sa_upgrade_txholds(tx, szp);
        zfs_sa_upgrade_txholds(tx, dzp);
        error = dmu_tx_assign(tx, TXG_WAIT);
        if (error) {
                dmu_tx_abort(tx);
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        error = zfs_link_create(dzp, name, szp, tx, 0);

        if (error == 0) {
                uint64_t txtype = TX_LINK;
                zfs_log_link(zilog, tx, txtype, dzp, szp, name);
        }

        dmu_tx_commit(tx);

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

        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        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_sa_hdl == NULL) {
                /*
                 * The fs has been unmounted, or we did a
                 * suspend/resume and this file no longer exists.
                 */
                rw_exit(&zfsvfs->z_teardown_inactive_lock);
                vrecycle(vp);
                return;
        }

        if (zp->z_unlinked) {
                /*
                 * Fast path to recycle a vnode of a removed file.
                 */
                rw_exit(&zfsvfs->z_teardown_inactive_lock);
                vrecycle(vp);
                return;
        }

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

                dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
                zfs_sa_upgrade_txholds(tx, zp);
                error = dmu_tx_assign(tx, TXG_WAIT);
                if (error) {
                        dmu_tx_abort(tx);
                } else {
                        (void) sa_update(zp->z_sa_hdl, SA_ZPL_ATIME(zfsvfs),
                            (void *)&zp->z_atime, sizeof (zp->z_atime), tx);
                        zp->z_atime_dirty = 0;
                        dmu_tx_commit(tx);
                }
        }
        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        gen64;
        uint64_t        object = zp->z_id;
        zfid_short_t    *zfid;
        int             size, i, error;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        if ((error = sa_lookup(zp->z_sa_hdl, SA_ZPL_GEN(zfsvfs),
            &gen64, sizeof (uint64_t))) != 0) {
                ZFS_EXIT(zfsvfs);
                return (error);
        }

        gen = (uint32_t)gen64;

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

#ifdef illumos
        if (fidp->fid_len < size) {
                fidp->fid_len = size;
                ZFS_EXIT(zfsvfs);
                return (SET_ERROR(ENOSPC));
        }
#else
        fidp->fid_len = size;
#endif

        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;
        int             error;

        switch (cmd) {
        case _PC_LINK_MAX:
                *valp = MIN(LONG_MAX, ZFS_LINK_MAX);
                return (0);

        case _PC_FILESIZEBITS:
                *valp = 64;
                return (0);
#ifdef illumos
        case _PC_XATTR_EXISTS:
                zp = VTOZ(vp);
                zfsvfs = zp->z_zfsvfs;
                ZFS_ENTER(zfsvfs);
                ZFS_VERIFY_ZP(zp);
                *valp = 0;
                error = zfs_dirent_lookup(zp, "", &xzp,
                    ZXATTR | ZEXISTS | ZSHARED);
                if (error == 0) {
                        if (!zfs_dirempty(xzp))
                                *valp = 1;
                        vrele(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);

        case _PC_SATTR_ENABLED:
        case _PC_SATTR_EXISTS:
                *valp = vfs_has_feature(vp->v_vfsp, VFSFT_SYSATTR_VIEWS) &&
                    (vp->v_type == VREG || vp->v_type == VDIR);
                return (0);

        case _PC_ACCESS_FILTERING:
                *valp = vfs_has_feature(vp->v_vfsp, VFSFT_ACCESS_FILTER) &&
                    vp->v_type == VDIR;
                return (0);

        case _PC_ACL_ENABLED:
                *valp = _ACL_ACE_ENABLED;
                return (0);
#endif  /* illumos */
        case _PC_MIN_HOLE_SIZE:
                *valp = (int)SPA_MINBLOCKSIZE;
                return (0);
#ifdef illumos
        case _PC_TIMESTAMP_RESOLUTION:
                /* nanosecond timestamp resolution */
                *valp = 1L;
                return (0);
#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);

        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*/
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;
        zilog_t *zilog = zfsvfs->z_log;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        error = zfs_setacl(zp, vsecp, skipaclchk, cr);

        if (zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zilog, 0);

        ZFS_EXIT(zfsvfs);
        return (error);
}

static int
zfs_getpages(struct vnode *vp, vm_page_t *ma, int count, int *rbehind,
    int *rahead)
{
        znode_t *zp = VTOZ(vp);
        zfsvfs_t *zfsvfs = zp->z_zfsvfs;
        objset_t *os = zp->z_zfsvfs->z_os;
        rl_t *rl;
        vm_object_t object;
        off_t start, end, obj_size;
        uint_t blksz;
        int pgsin_b, pgsin_a;
        int error;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        start = IDX_TO_OFF(ma[0]->pindex);
        end = IDX_TO_OFF(ma[count - 1]->pindex + 1);

        /*
         * Lock a range covering all required and optional pages.
         * Note that we need to handle the case of the block size growing.
         */
        for (;;) {
                blksz = zp->z_blksz;
                rl = zfs_range_lock(zp, rounddown(start, blksz),
                    roundup(end, blksz) - rounddown(start, blksz), RL_READER);
                if (blksz == zp->z_blksz)
                        break;
                zfs_range_unlock(rl);
        }

        object = ma[0]->object;
        zfs_vmobject_wlock(object);
        obj_size = object->un_pager.vnp.vnp_size;
        zfs_vmobject_wunlock(object);
        if (IDX_TO_OFF(ma[count - 1]->pindex) >= obj_size) {
                zfs_range_unlock(rl);
                ZFS_EXIT(zfsvfs);
                return (zfs_vm_pagerret_bad);
        }

        pgsin_b = 0;
        if (rbehind != NULL) {
                pgsin_b = OFF_TO_IDX(start - rounddown(start, blksz));
                pgsin_b = MIN(*rbehind, pgsin_b);
        }

        pgsin_a = 0;
        if (rahead != NULL) {
                pgsin_a = OFF_TO_IDX(roundup(end, blksz) - end);
                if (end + IDX_TO_OFF(pgsin_a) >= obj_size)
                        pgsin_a = OFF_TO_IDX(round_page(obj_size) - end);
                pgsin_a = MIN(*rahead, pgsin_a);
        }

        /*
         * NB: we need to pass the exact byte size of the data that we expect
         * to read after accounting for the file size.  This is required because
         * ZFS will panic if we request DMU to read beyond the end of the last
         * allocated block.
         */
        error = dmu_read_pages(os, zp->z_id, ma, count, &pgsin_b, &pgsin_a,
            MIN(end, obj_size) - (end - PAGE_SIZE));

        zfs_range_unlock(rl);
        ZFS_ACCESSTIME_STAMP(zfsvfs, zp);
        ZFS_EXIT(zfsvfs);

        if (error != 0)
                return (zfs_vm_pagerret_error);

        VM_CNT_INC(v_vnodein);
        VM_CNT_ADD(v_vnodepgsin, count + pgsin_b + pgsin_a);
        if (rbehind != NULL)
                *rbehind = pgsin_b;
        if (rahead != NULL)
                *rahead = pgsin_a;
        return (zfs_vm_pagerret_ok);
}

static int
zfs_freebsd_getpages(ap)
        struct vop_getpages_args /* {
                struct vnode *a_vp;
                vm_page_t *a_m;
                int a_count;
                int *a_rbehind;
                int *a_rahead;
        } */ *ap;
{

        return (zfs_getpages(ap->a_vp, ap->a_m, ap->a_count, ap->a_rbehind,
            ap->a_rahead));
}

static int
zfs_putpages(struct vnode *vp, vm_page_t *ma, size_t len, int flags,
    int *rtvals)
{
        znode_t         *zp = VTOZ(vp);
        zfsvfs_t        *zfsvfs = zp->z_zfsvfs;
        rl_t            *rl;
        dmu_tx_t        *tx;
        struct sf_buf   *sf;
        vm_object_t     object;
        vm_page_t       m;
        caddr_t         va;
        size_t          tocopy;
        size_t          lo_len;
        vm_ooffset_t    lo_off;
        vm_ooffset_t    off;
        uint_t          blksz;
        int             ncount;
        int             pcount;
        int             err;
        int             i;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        object = vp->v_object;
        pcount = btoc(len);
        ncount = pcount;

        KASSERT(ma[0]->object == object, ("mismatching object"));
        KASSERT(len > 0 && (len & PAGE_MASK) == 0, ("unexpected length"));

        for (i = 0; i < pcount; i++)
                rtvals[i] = zfs_vm_pagerret_error;

        off = IDX_TO_OFF(ma[0]->pindex);
        blksz = zp->z_blksz;
        lo_off = rounddown(off, blksz);
        lo_len = roundup(len + (off - lo_off), blksz);
        rl = zfs_range_lock(zp, lo_off, lo_len, RL_WRITER);

        zfs_vmobject_wlock(object);
        if (len + off > object->un_pager.vnp.vnp_size) {
                if (object->un_pager.vnp.vnp_size > off) {
                        int pgoff;

                        len = object->un_pager.vnp.vnp_size - off;
                        ncount = btoc(len);
                        if ((pgoff = (int)len & PAGE_MASK) != 0) {
                                /*
                                 * If the object is locked and the following
                                 * conditions hold, then the page's dirty
                                 * field cannot be concurrently changed by a
                                 * pmap operation.
                                 */
                                m = ma[ncount - 1];
                                vm_page_assert_sbusied(m);
                                KASSERT(!pmap_page_is_write_mapped(m),
                                    ("zfs_putpages: page %p is not read-only", m));
                                vm_page_clear_dirty(m, pgoff, PAGE_SIZE -
                                    pgoff);
                        }
                } else {
                        len = 0;
                        ncount = 0;
                }
                if (ncount < pcount) {
                        for (i = ncount; i < pcount; i++) {
                                rtvals[i] = zfs_vm_pagerret_bad;
                        }
                }
        }
        zfs_vmobject_wunlock(object);

        if (ncount == 0)
                goto out;

        if (zfs_owner_overquota(zfsvfs, zp, B_FALSE) ||
            zfs_owner_overquota(zfsvfs, zp, B_TRUE)) {
                goto out;
        }

        tx = dmu_tx_create(zfsvfs->z_os);
        dmu_tx_hold_write(tx, zp->z_id, off, len);

        dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
        zfs_sa_upgrade_txholds(tx, zp);
        err = dmu_tx_assign(tx, TXG_WAIT);
        if (err != 0) {
                dmu_tx_abort(tx);
                goto out;
        }

        if (zp->z_blksz < PAGE_SIZE) {
                for (i = 0; len > 0; off += tocopy, len -= tocopy, i++) {
                        tocopy = len > PAGE_SIZE ? PAGE_SIZE : len;
                        va = zfs_map_page(ma[i], &sf);
                        dmu_write(zfsvfs->z_os, zp->z_id, off, tocopy, va, tx);
                        zfs_unmap_page(sf);
                }
        } else {
                err = dmu_write_pages(zfsvfs->z_os, zp->z_id, off, len, ma, tx);
        }

        if (err == 0) {
                uint64_t mtime[2], ctime[2];
                sa_bulk_attr_t bulk[3];
                int count = 0;

                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs), NULL,
                    &mtime, 16);
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL,
                    &ctime, 16);
                SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs), NULL,
                    &zp->z_pflags, 8);
                zfs_tstamp_update_setup(zp, CONTENT_MODIFIED, mtime, ctime,
                    B_TRUE);
                err = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
                ASSERT0(err);
                zfs_log_write(zfsvfs->z_log, tx, TX_WRITE, zp, off, len, 0);

                zfs_vmobject_wlock(object);
                for (i = 0; i < ncount; i++) {
                        rtvals[i] = zfs_vm_pagerret_ok;
                        vm_page_undirty(ma[i]);
                }
                zfs_vmobject_wunlock(object);
                VM_CNT_INC(v_vnodeout);
                VM_CNT_ADD(v_vnodepgsout, ncount);
        }
        dmu_tx_commit(tx);

out:
        zfs_range_unlock(rl);
        if ((flags & (zfs_vm_pagerput_sync | zfs_vm_pagerput_inval)) != 0 ||
            zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
                zil_commit(zfsvfs->z_log, zp->z_id);
        ZFS_EXIT(zfsvfs);
        return (rtvals[0]);
}

int
zfs_freebsd_putpages(ap)
        struct vop_putpages_args /* {
                struct vnode *a_vp;
                vm_page_t *a_m;
                int a_count;
                int a_sync;
                int *a_rtvals;
        } */ *ap;
{

        return (zfs_putpages(ap->a_vp, ap->a_m, ap->a_count, ap->a_sync,
            ap->a_rtvals));
}

static int
zfs_freebsd_bmap(ap)
        struct vop_bmap_args /* {
                struct vnode *a_vp;
                daddr_t  a_bn;
                struct bufobj **a_bop;
                daddr_t *a_bnp;
                int *a_runp;
                int *a_runb;
        } */ *ap;
{

        if (ap->a_bop != NULL)
                *ap->a_bop = &ap->a_vp->v_bufobj;
        if (ap->a_bnp != NULL)
                *ap->a_bnp = ap->a_bn;
        if (ap->a_runp != NULL)
                *ap->a_runp = 0;
        if (ap->a_runb != NULL)
                *ap->a_runb = 0;

        return (0);
}

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_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, 1, 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
ioflags(int ioflags)
{
        int flags = 0;

        if (ioflags & IO_APPEND)
                flags |= FAPPEND;
        if (ioflags & IO_NDELAY)
                flags |= FNONBLOCK;
        if (ioflags & IO_SYNC)
                flags |= (FSYNC | FDSYNC | FRSYNC);

        return (flags);
}

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, ioflags(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, ioflags(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;
{
        vnode_t *vp = ap->a_vp;
        znode_t *zp = VTOZ(vp);
        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) {
                        error = vaccess(vp->v_type, zp->z_mode, zp->z_uid,
                            zp->z_gid, accmode, ap->a_cred, NULL);
                }
        }

        /*
         * For VEXEC, ensure that at least one execute bit is set for
         * non-directories.
         */
        if (error == 0 && (ap->a_accmode & VEXEC) != 0 && vp->v_type != VDIR &&
            (zp->z_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0) {
                error = EACCES;
        }

        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_cache_lookup(ap)
        struct vop_lookup_args /* {
                struct vnode *a_dvp;
                struct vnode **a_vpp;
                struct componentname *a_cnp;
        } */ *ap;
{
        zfsvfs_t *zfsvfs;

        zfsvfs = ap->a_dvp->v_mount->mnt_data;
        if (zfsvfs->z_use_namecache)
                return (vfs_cache_lookup(ap));
        else
                return (zfs_freebsd_lookup(ap));
}

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;
{
        zfsvfs_t *zfsvfs;
        struct componentname *cnp = ap->a_cnp;
        vattr_t *vap = ap->a_vap;
        int error, mode;

        ASSERT(cnp->cn_flags & SAVENAME);

        vattr_init_mask(vap);
        mode = vap->va_mode & ALLPERMS;
        zfsvfs = ap->a_dvp->v_mount->mnt_data;

        error = zfs_create(ap->a_dvp, cnp->cn_nameptr, vap, !EXCL, mode,
            ap->a_vpp, cnp->cn_cred, cnp->cn_thread);
        if (zfsvfs->z_use_namecache &&
            error == 0 && (cnp->cn_flags & MAKEENTRY) != 0)
                cache_enter(ap->a_dvp, *ap->a_vpp, cnp);
        return (error);
}

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_vp, ap->a_cnp->cn_nameptr,
            ap->a_cnp->cn_cred));
}

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));
}

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, ap->a_vp, cnp->cn_nameptr, cnp->cn_cred));
}

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;
        } */ *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);
        XVA_SET_REQ(&xvap, XAT_READONLY);
        XVA_SET_REQ(&xvap, XAT_ARCHIVE);
        XVA_SET_REQ(&xvap, XAT_SYSTEM);
        XVA_SET_REQ(&xvap, XAT_HIDDEN);
        XVA_SET_REQ(&xvap, XAT_REPARSE);
        XVA_SET_REQ(&xvap, XAT_OFFLINE);
        XVA_SET_REQ(&xvap, XAT_SPARSE);

        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_ARCHIVE, XAT_ARCHIVE,
            xvap.xva_xoptattrs.xoa_archive);
        FLAG_CHECK(UF_NODUMP, XAT_NODUMP,
            xvap.xva_xoptattrs.xoa_nodump);
        FLAG_CHECK(UF_READONLY, XAT_READONLY,
            xvap.xva_xoptattrs.xoa_readonly);
        FLAG_CHECK(UF_SYSTEM, XAT_SYSTEM,
            xvap.xva_xoptattrs.xoa_system);
        FLAG_CHECK(UF_HIDDEN, XAT_HIDDEN,
            xvap.xva_xoptattrs.xoa_hidden);
        FLAG_CHECK(UF_REPARSE, XAT_REPARSE,
            xvap.xva_xoptattrs.xoa_reparse);
        FLAG_CHECK(UF_OFFLINE, XAT_OFFLINE,
            xvap.xva_xoptattrs.xoa_offline);
        FLAG_CHECK(UF_SPARSE, XAT_SPARSE,
            xvap.xva_xoptattrs.xoa_sparse);

#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;
        } */ *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_pflags;

        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;
                /*
                 * XXX KDM 
                 * We need to figure out whether it makes sense to allow
                 * UF_REPARSE through, since we don't really have other
                 * facilities to handle reparse points and zfs_setattr()
                 * doesn't currently allow setting that attribute anyway.
                 */
                if ((fflags & ~(SF_IMMUTABLE|SF_APPEND|SF_NOUNLINK|UF_ARCHIVE|
                     UF_NODUMP|UF_SYSTEM|UF_HIDDEN|UF_READONLY|UF_REPARSE|
                     UF_OFFLINE|UF_SPARSE)) != 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 PR_ALLOW_CHFLAGS permission bit is set;
                 * otherwise, they behave like unprivileged processes.
                 */
                if (secpolicy_fs_owner(vp->v_mount, cred) == 0 ||
                    priv_check_cred(cred, PRIV_VFS_SYSFLAGS) == 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_ARCHIVE, ZFS_ARCHIVE, XAT_ARCHIVE,
                    xvap.xva_xoptattrs.xoa_archive);
                FLAG_CHANGE(UF_NODUMP, ZFS_NODUMP, XAT_NODUMP,
                    xvap.xva_xoptattrs.xoa_nodump);
                FLAG_CHANGE(UF_READONLY, ZFS_READONLY, XAT_READONLY,
                    xvap.xva_xoptattrs.xoa_readonly);
                FLAG_CHANGE(UF_SYSTEM, ZFS_SYSTEM, XAT_SYSTEM,
                    xvap.xva_xoptattrs.xoa_system);
                FLAG_CHANGE(UF_HIDDEN, ZFS_HIDDEN, XAT_HIDDEN,
                    xvap.xva_xoptattrs.xoa_hidden);
                FLAG_CHANGE(UF_REPARSE, ZFS_REPARSE, XAT_REPARSE,
                    xvap.xva_xoptattrs.xoa_reparse);
                FLAG_CHANGE(UF_OFFLINE, ZFS_OFFLINE, XAT_OFFLINE,
                    xvap.xva_xoptattrs.xoa_offline);
                FLAG_CHANGE(UF_SPARSE, ZFS_SPARSE, XAT_SPARSE,
                    xvap.xva_xoptattrs.xoa_sparse);
#undef  FLAG_CHANGE
        }
        if (vap->va_birthtime.tv_sec != VNOVAL) {
                xvap.xva_vattr.va_mask |= AT_XVATTR;
                XVA_SET_REQ(&xvap, XAT_CREATETIME);
        }
        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, &fvp, ap->a_fcnp, tdvp, &tvp,
            ap->a_tcnp, ap->a_fcnp->cn_cred);

        vrele(fdvp);
        vrele(fvp);
        vrele(tdvp);
        if (tvp != NULL)
                vrele(tvp);

        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,
            __DECONST(char *, 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;
        vnode_t *vp = ap->a_vp;
        vnode_t *tdvp = ap->a_tdvp;

        if (tdvp->v_mount != vp->v_mount)
                return (EXDEV);

        ASSERT(cnp->cn_flags & SAVENAME);

        return (zfs_link(tdvp, 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 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;

        ASSERT(zp != NULL);

        /*
         * z_teardown_inactive_lock protects from a race with
         * zfs_znode_dmu_fini in zfsvfs_teardown during
         * force unmount.
         */
        rw_enter(&zfsvfs->z_teardown_inactive_lock, RW_READER);
        if (zp->z_sa_hdl == NULL)
                zfs_znode_free(zp);
        else
                zfs_zinactive(zp);
        rw_exit(&zfsvfs->z_teardown_inactive_lock);

        vp->v_data = NULL;
        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;
                return (error);
        }
        if (error != EOPNOTSUPP)
                return (error);

        switch (ap->a_name) {
        case _PC_NAME_MAX:
                *ap->a_retval = NAME_MAX;
                return (0);
        case _PC_PIPE_BUF:
                if (ap->a_vp->v_type == VDIR || ap->a_vp->v_type == VFIFO) {
                        *ap->a_retval = PIPE_BUF;
                        return (0);
                }
                return (EINVAL);
        default:
                return (vop_stdpathconf(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, 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, 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,
            UIO_SYSSPACE, attrname, xvp, td);
        error = namei(&nd);
        vp = nd.ni_vp;
        if (error != 0) {
                ZFS_EXIT(zfsvfs);
                NDFREE(&nd, NDF_ONLY_PNBUF);
                if (error == ENOENT)
                        error = ENOATTR;
                return (error);
        }

        error = VOP_REMOVE(nd.ni_dvp, vp, &nd.ni_cnd);
        NDFREE(&nd, NDF_ONLY_PNBUF);

        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, 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, 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,
            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 == NULL)
                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);
}

static int
zfs_vptocnp(struct vop_vptocnp_args *ap)
{
        vnode_t *covered_vp;
        vnode_t *vp = ap->a_vp;;
        zfsvfs_t *zfsvfs = vp->v_vfsp->vfs_data;
        znode_t *zp = VTOZ(vp);
        enum vgetstate vs;
        int ltype;
        int error;

        ZFS_ENTER(zfsvfs);
        ZFS_VERIFY_ZP(zp);

        /*
         * If we are a snapshot mounted under .zfs, run the operation
         * on the covered vnode.
         */
        if (zp->z_id != zfsvfs->z_root || zfsvfs->z_parent == zfsvfs) {
                char name[MAXNAMLEN + 1];
                znode_t *dzp;
                size_t len;

                error = zfs_znode_parent_and_name(zp, &dzp, name);
                if (error == 0) {
                        len = strlen(name);
                        if (*ap->a_buflen < len)
                                error = SET_ERROR(ENOMEM);
                }
                if (error == 0) {
                        *ap->a_buflen -= len;
                        bcopy(name, ap->a_buf + *ap->a_buflen, len);
                        *ap->a_vpp = ZTOV(dzp);
                }
                ZFS_EXIT(zfsvfs);
                return (error);
        }
        ZFS_EXIT(zfsvfs);

        covered_vp = vp->v_mount->mnt_vnodecovered;
        vs = vget_prep(covered_vp);
        ltype = VOP_ISLOCKED(vp);
        VOP_UNLOCK(vp, 0);
        error = vget_finish(covered_vp, LK_SHARED, vs);
        if (error == 0) {
                error = VOP_VPTOCNP(covered_vp, ap->a_vpp, ap->a_cred,
                    ap->a_buf, ap->a_buflen);
                vput(covered_vp);
        }
        vn_lock(vp, ltype | LK_RETRY);
        if ((vp->v_iflag & VI_DOOMED) != 0)
                error = SET_ERROR(ENOENT);
        return (error);
}

#ifdef DIAGNOSTIC
static int
zfs_lock(ap)
        struct vop_lock1_args /* {
                struct vnode *a_vp;
                int a_flags;
                char *file;
                int line;
        } */ *ap;
{
        vnode_t *vp;
        znode_t *zp;
        int err;

        err = vop_stdlock(ap);
        if (err == 0 && (ap->a_flags & LK_NOWAIT) == 0) {
                vp = ap->a_vp;
                zp = vp->v_data;
                if (vp->v_mount != NULL && (vp->v_iflag & VI_DOOMED) == 0 &&
                    zp != NULL && (zp->z_pflags & ZFS_XATTR) == 0)
                        VERIFY(!RRM_LOCK_HELD(&zp->z_zfsvfs->z_teardown_lock));
        }
        return (err);
}
#endif

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,
        .vop_allocate =         VOP_EINVAL,
        .vop_lookup =           zfs_cache_lookup,
        .vop_cachedlookup =     zfs_freebsd_lookup,
        .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 =             zfs_freebsd_bmap,
        .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,
        .vop_getpages =         zfs_freebsd_getpages,
        .vop_putpages =         zfs_freebsd_putpages,
        .vop_vptocnp =          zfs_vptocnp,
#ifdef DIAGNOSTIC
        .vop_lock1 =            zfs_lock,
#endif
};

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_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,
};