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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 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/* Portions Copyright 2007 Jeremy Teo */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/systm.h>
#include <sys/sysmacros.h>
#include <sys/resource.h>
#include <sys/vfs.h>
#include <sys/vfs_opreg.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/vmsystm.h>
#include <sys/atomic.h>
#include <sys/vm.h>
#include <vm/seg_vn.h>
#include <vm/pvn.h>
#include <vm/as.h>
#include <vm/kpm.h>
#include <vm/seg_kpm.h>
#include <sys/mman.h>
#include <sys/pathname.h>
#include <sys/cmn_err.h>
#include <sys/errno.h>
#include <sys/unistd.h>
#include <sys/zfs_dir.h>
#include <sys/zfs_acl.h>
#include <sys/zfs_ioctl.h>
#include <sys/fs/zfs.h>
#include <sys/dmu.h>
#include <sys/spa.h>
#include <sys/txg.h>
#include <sys/dbuf.h>
#include <sys/zap.h>
#include <sys/dirent.h>
#include <sys/policy.h>
#include <sys/sunddi.h>
#include <sys/filio.h>
#include <sys/sid.h>
#include "fs/fs_subr.h"
#include <sys/zfs_ctldir.h>
#include <sys/zfs_fuid.h>
#include <sys/dnlc.h>
#include <sys/zfs_rlock.h>
#include <sys/extdirent.h>
#include <sys/kidmap.h>
#include <sys/cred_impl.h>
#include <sys/attr.h>
#include "zfsfuse_socket.h"

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

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

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zp);

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

      /* ZFS-FUSE: virus scan not implemented.. */
#if 0
      if (!zfs_has_ctldir(zp) && zp->z_zfsvfs->z_vscan &&
          ZTOV(zp)->v_type == VREG &&
          !(zp->z_phys->zp_flags & ZFS_AV_QUARANTINED) &&
          zp->z_phys->zp_size > 0) {
            if (fs_vscan(*vpp, cr, 0) != 0) {
                  ZFS_EXIT(zfsvfs);
                  return (EACCES);
            }
      }
#endif

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

      ZFS_EXIT(zfsvfs);
      return (0);
}

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

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zp);

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

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

      /* ZFS-FUSE: virus scan not implemented.. */
#if 0
      if (!zfs_has_ctldir(zp) && zp->z_zfsvfs->z_vscan &&
          ZTOV(zp)->v_type == VREG &&
          !(zp->z_phys->zp_flags & ZFS_AV_QUARANTINED) &&
          zp->z_phys->zp_size > 0)
            VERIFY(fs_vscan(vp, cr, 1) == 0);
#endif

      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.
 */
/* ZFSFUSE: not implemented */
#if 0
static int
zfs_holey(vnode_t *vp, int cmd, offset_t *off)
{
      znode_t     *zp = VTOZ(vp);
      uint64_t noff = (uint64_t)*off; /* new offset */
      uint64_t file_sz;
      int error;
      boolean_t hole;

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

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

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

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

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

/* ARGSUSED */
static int
zfs_ioctl(vnode_t *vp, int com, intptr_t data, int flag, cred_t *cred,
    int *rvalp, caller_context_t *ct)
{
      /* ZFSFUSE: not implemented */
      abort();
#if 0
      offset_t off;
      int error;
      zfsvfs_t *zfsvfs;
      znode_t *zp;

      switch (com) {
      case _FIOFFS:
            return (zfs_sync(vp->v_vfsp, 0, cred));

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

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

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

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

/*
 * Utility functions to map and unmap a single physical page.  These
 * are used to manage the mappable copies of ZFS file data, and therefore
 * do not update ref/mod bits.
 */
/* ZFSFUSE: not needed */
#if 0
caddr_t
zfs_map_page(page_t *pp, enum seg_rw rw)
{
      if (kpm_enable)
            return (hat_kpm_mapin(pp, 0));
      ASSERT(rw == S_READ || rw == S_WRITE);
      return (ppmapin(pp, PROT_READ | ((rw == S_WRITE) ? PROT_WRITE : 0),
          (caddr_t)-1));
}

void
zfs_unmap_page(page_t *pp, caddr_t addr)
{
      if (kpm_enable) {
            hat_kpm_mapout(pp, 0, addr);
      } else {
            ppmapout(addr);
      }
}
#endif

/*
 * 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)
{
       /* ZFSFUSE: not implemented */
       abort();
#if 0

      int64_t     off;

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

            if (pp = page_lookup(vp, start, SE_SHARED)) {
                  caddr_t va;

                  va = zfs_map_page(pp, S_WRITE);
                  (void) dmu_read(os, oid, start+off, nbytes, va+off,
                      DMU_READ_PREFETCH);
                  zfs_unmap_page(pp, va);
                  page_unlock(pp);
            }
            len -= nbytes;
            off = 0;
      }
#endif
}

/*
 * 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)
{
      /* ZFSFUSE: not implemented */
      abort();
#if 0
      znode_t *zp = VTOZ(vp);
      objset_t *os = zp->z_zfsvfs->z_os;
      int64_t     start, off;
      int len = nbytes;
      int error = 0;

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

            if (pp = page_lookup(vp, start, SE_SHARED)) {
                  caddr_t va;

                  va = zfs_map_page(pp, S_READ);
                  error = uiomove(va + off, bytes, UIO_READ, uio);
                  zfs_unmap_page(pp, va);
                  page_unlock(pp);
            } else {
                  error = dmu_read_uio(os, zp->z_id, uio, bytes);
            }
            len -= bytes;
            off = 0;
            if (error)
                  break;
      }
      return (error);
#endif
}

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

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

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

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

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

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

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

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

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

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

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

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

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

            n -= nbytes;
      }

out:
      zfs_range_unlock(rl);

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

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

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

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

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zp);

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

      zilog = zfsvfs->z_log;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

      zfs_range_unlock(rl);

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

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

      ZFS_EXIT(zfsvfs);
      return (0);
}

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

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

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

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

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

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

            /*
             * Have to lock the whole block to ensure when it's
             * written out and it's checksum is being calculated
             * that no one can change the data. We need to re-check
             * blocksize after we get the lock in case it's changed!
             */
            for (;;) {
                  if (ISP2(zp->z_blksz)) {
                        boff = P2ALIGN_TYPED(off, zp->z_blksz,
                            uint64_t);
                  } else {
                        boff = 0;
                  }
                  dlen = zp->z_blksz;
                  rl = zfs_range_lock(zp, boff, dlen, RL_READER);
                  if (zp->z_blksz == dlen)
                        break;
                  zfs_range_unlock(rl);
            }
            /* test for truncation needs to be done while range locked */
            if (off >= zp->z_phys->zp_size) {
                  error = ENOENT;
                  goto out;
            }
            zgd = (zgd_t *)kmem_alloc(sizeof (zgd_t), KM_SLEEP);
            zgd->zgd_rl = rl;
            zgd->zgd_zilog = zfsvfs->z_log;
            zgd->zgd_bp = &lr->lr_blkptr;
            VERIFY(0 == dmu_buf_hold(os, lr->lr_foid, boff, zgd, &db));
            ASSERT(boff == db->db_offset);
            lr->lr_blkoff = off - boff;
            error = dmu_sync(zio, db, &lr->lr_blkptr,
                lr->lr_common.lrc_txg, zfs_get_done, zgd);
            ASSERT((error && error != EINPROGRESS) ||
                lr->lr_length <= zp->z_blksz);
            if (error == 0)
                  zil_add_block(zfsvfs->z_log, &lr->lr_blkptr);
            /*
             * If we get EINPROGRESS, then we need to wait for a
             * write IO initiated by dmu_sync() to complete before
             * we can release this dbuf.  We will finish everything
             * up in the zfs_get_done() callback.
             */
            if (error == EINPROGRESS)
                  return (0);
            dmu_buf_rele(db, zgd);
            kmem_free(zgd, sizeof (zgd_t));
      }
out:
      zfs_range_unlock(rl);
      /*
       * Release the vnode asynchronously as we currently have the
       * txg stopped from syncing.
       */
      VN_RELE_ASYNC(ZTOV(zp), dsl_pool_vnrele_taskq(dmu_objset_pool(os)));
      return (error);
}

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

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zp);

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

      ZFS_EXIT(zfsvfs);
      return (error);
}

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

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zdp);

      *vpp = NULL;

      if (flags & LOOKUP_XATTR) {
            /* ZFSFUSE: not implemented */
            ZFS_EXIT(zfsvfs);
            return (EINVAL);
            /*
             * If the xattr property is off, refuse the lookup request.
             */
            if (!(zfsvfs->z_vfs->vfs_flag & VFS_XATTR)) {
                  ZFS_EXIT(zfsvfs);
                  return (EINVAL);
            }

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

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

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

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

            ZFS_EXIT(zfsvfs);
            return (error);
      }

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

      /*
       * Check accessibility of directory.
       */

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

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

      error = zfs_dirlook(zdp, nm, vpp, flags, direntflags, realpnp);
      if (error == 0) {
            /*
             * Convert device special files
             */
/* ZFSFUSE: unneeded? */
#if 0
            if (IS_DEVVP(*vpp)) {
                  vnode_t     *svp;

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

      ZFS_EXIT(zfsvfs);
      return (error);
}

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

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

      /*
       * 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 (EINVAL);

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

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

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

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

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

            if (flag & FIGNORECASE)
                  zflg |= ZCILOOK;

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

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

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

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

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

            if (fuid_dirtied)
                  zfs_fuid_sync(zfsvfs, tx);

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

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

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

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

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

      if (dl)
            zfs_dirent_unlock(dl);

      if (error) {
            if (zp)
                  VN_RELE(ZTOV(zp));
      } else {
            *vpp = ZTOV(zp);
            /*
             * If vnode is for a device return a specfs vnode instead.
             */
/* ZFSFUSE: unneeded? */
#if 0
            if (IS_DEVVP(*vpp)) {
                  struct vnode *svp;

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

      ZFS_EXIT(zfsvfs);
      return (error);
}

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

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

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

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

      vp = ZTOV(zp);

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

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

      vnevent_remove(vp, dvp, name, ct);

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

      mutex_enter(&vp->v_lock);
      may_delete_now = vp->v_count == 1 && !vn_has_cached_data(vp);
      mutex_exit(&vp->v_lock);

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

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

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

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

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

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

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

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

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

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

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

      zfs_dirent_unlock(dl);

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

      ZFS_EXIT(zfsvfs);
      return (error);
}

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

      ASSERT(vap->va_type == VDIR);

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

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

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

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

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

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

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

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

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

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

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

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

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

      *vpp = ZTOV(zp);

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

      zfs_acl_ids_free(&acl_ids);
      dmu_tx_commit(tx);

      zfs_dirent_unlock(dl);

      ZFS_EXIT(zfsvfs);
      return (0);
}

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

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

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

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

      vp = ZTOV(zp);

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

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

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

      vnevent_rmdir(vp, dvp, name, ct);

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

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

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

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

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

      dmu_tx_commit(tx);

      rw_exit(&zp->z_parent_lock);
      rw_exit(&zp->z_name_lock);
out:
      zfs_dirent_unlock(dl);

      VN_RELE(vp);

      ZFS_EXIT(zfsvfs);
      return (error);
}

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

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zp);

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

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

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

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

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

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

      /*
       * If 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.
       */
      /* ZFSFUSE: we don't care */
      check_sysattrs = B_FALSE;

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

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

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

                  objnum = ZFS_DIRENT_OBJ(zap.za_first_integer);
                  /*
                   * MacOS X can extract the object type here such as:
                   * uint8_t type = ZFS_DIRENT_TYPE(zap.za_first_integer);
                   */
                  /* ZFSFUSE: don't care */
#if 0
                  if (check_sysattrs && !zap.za_normalization_conflict) {
                        zap.za_normalization_conflict =
                            xattr_sysattr_casechk(zap.za_name);
                  }
 #endif
            }

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

            /*
             * Will this entry fit in the buffer?
             */
            if (outcount + reclen > bufsize) {
                  /*
                   * Did we manage to fit anything in the buffer?
                   */
                  if (!outcount) {
                        error = EINVAL;
                        goto update;
                  }
                  break;
            }
            if (flags & V_RDDIR_ENTFLAGS) {
                  /*
                   * Add extended flag entry:
                   */
                  eodp->ed_ino = objnum;
                  eodp->ed_reclen = reclen;
                  /* NOTE: ed_off is the offset for the *next* entry */
                  next = &(eodp->ed_off);
                  eodp->ed_eflags = zap.za_normalization_conflict ?
                      ED_CASE_CONFLICT : 0;
                  (void) strncpy(eodp->ed_name, zap.za_name,
                      EDIRENT_NAMELEN(reclen));
                  eodp = (edirent_t *)((intptr_t)eodp + reclen);
            } else {
                  /*
                   * Add normal entry:
                   */
                  odp->d_ino = objnum;
                  odp->d_reclen = reclen;
                  /* NOTE: d_off is the offset for the *next* entry */
                  next = &(odp->d_off);
                  (void) strncpy(odp->d_name, zap.za_name,
                      DIRENT64_NAMELEN(reclen));
                  odp = (dirent64_t *)((intptr_t)odp + reclen);
            }
            outcount += reclen;

            ASSERT(outcount <= bufsize);

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

            /*
             * 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;
            }
            *next = offset;
      }
      zp->z_zn_prefetch = B_FALSE; /* a lookup will re-enable pre-fetching */

      if (uio->uio_segflg == UIO_SYSSPACE && uio->uio_iovcnt == 1) {
            iovp->iov_base = ((char *) 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);
      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;

      /*
       * Regardless of whether this is required for standards conformance,
       * this is the logical behavior when fsync() is called on a file with
       * dirty pages.  We use B_ASYNC since the ZIL transactions are already
       * going to be pushed out as part of the zil_commit().
       */
      if (vn_has_cached_data(vp) && !(syncflag & FNODSYNC) &&
          (vp->v_type == VREG) && !(IS_SWAPVP(vp)))
            (void) VOP_PUTPAGE(vp, (offset_t)0, (size_t)0, B_ASYNC, cr, ct);

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

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


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

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

      mutex_enter(&zp->z_lock);

      /*
       * If ACL is trivial don't bother looking for ACE_READ_ATTRIBUTES.
       * Also, if we are the owner don't bother, since owner should
       * always be allowed to read basic attributes of file.
       */
      if (!(pzp->zp_flags & ZFS_ACL_TRIVIAL) &&
          (pzp->zp_uid != crgetuid(cr))) {
            if (error = zfs_zaccess(zp, ACE_READ_ATTRIBUTES, 0,
                skipaclchk, cr)) {
                  mutex_exit(&zp->z_lock);
                  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 = vp->v_type;
      vap->va_mode = pzp->zp_mode & MODEMASK;
      zfs_fuid_map_ids(zp, cr, &vap->va_uid, &vap->va_gid);
      vap->va_fsid = zp->z_zfsvfs->z_vfs->vfs_dev;
      vap->va_nodeid = zp->z_id;
      if ((vp->v_flag & VROOT) && zfs_show_ctldir(zp))
            links = pzp->zp_links + 1;
      else
            links = pzp->zp_links;
      vap->va_nlink = MIN(links, UINT32_MAX);   /* nlink_t limit! */
      vap->va_size = pzp->zp_size;
      vap->va_rdev = vp->v_rdev;
      vap->va_seq = 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 =
                      ((pzp->zp_flags & ZFS_ARCHIVE) != 0);
                  XVA_SET_RTN(xvap, XAT_ARCHIVE);
            }

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

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

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

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

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

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

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

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

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

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

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

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

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

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

      mutex_exit(&zp->z_lock);

      dmu_object_size_from_db(zp->z_dbuf, &vap->va_blksize, &vap->va_nblocks);

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

      ZFS_EXIT(zfsvfs);
      return (0);
}

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

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

      if (mask & AT_NOSET)
            return (EINVAL);

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zp);

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

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

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

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

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

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

      xva_init(&tmpxvattr);

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

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

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

top:
      attrzp = NULL;

      if (zfsvfs->z_vfs->vfs_flag & VFS_RDONLY) {
            ZFS_EXIT(zfsvfs);
            return (EROFS);
      }

      /*
       * First validate permissions
       */

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

      mutex_exit(&zp->z_lock);

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

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

            if (trim_mask) {
                  saved_mask = vap->va_mask;
                  vap->va_mask &= ~trim_mask;
            }
            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;
      }

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

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

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

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

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

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

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

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

      dmu_buf_will_dirty(zp->z_dbuf, tx);

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

      mutex_enter(&zp->z_lock);

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

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

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

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

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

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

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

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

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

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

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

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

                  ASSERT(vp->v_type == VREG);

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

      if (fuid_dirtied)
            zfs_fuid_sync(zfsvfs, tx);

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

      mutex_exit(&zp->z_lock);

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

      if (aclp) {
            zfs_acl_free(aclp);
            aclp = NULL;
      }

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

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

      if (err == ERESTART)
            goto top;

      ZFS_EXIT(zfsvfs);
      return (err);
}

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

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

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

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

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

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

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

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

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

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

      return (0);
}

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

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

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

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

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

      if (flags & FIGNORECASE)
            zflg |= ZCILOOK;

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

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

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

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

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

      if (serr) {
            /*
             * Source entry invalid or not there.
             */
            if (!terr) {
                  zfs_dirent_unlock(tdl);
                  if (tzp)
                        VN_RELE(ZTOV(tzp));
            }
            if (strcmp(snm, "..") == 0)
                  serr = EINVAL;
            ZFS_EXIT(zfsvfs);
            return (serr);
      }
      if (terr) {
            zfs_dirent_unlock(sdl);
            VN_RELE(ZTOV(szp));
            if (strcmp(tnm, "..") == 0)
                  terr = EINVAL;
            ZFS_EXIT(zfsvfs);
            return (terr);
      }

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

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

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

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

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

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

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

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

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

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

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

                  /* Update path information for the target vnode */
                  vn_renamepath(tdvp, ZTOV(szp), tnm, strlen(tnm));
            }
      }

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

      zfs_dirent_unlock(sdl);
      zfs_dirent_unlock(tdl);

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

      ZFS_EXIT(zfsvfs);
      return (error);
}

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

      ASSERT(vap->va_type == VLNK);

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

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

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

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

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

      dmu_buf_will_dirty(dzp->z_dbuf, tx);

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

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

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

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

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

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

      zfs_acl_ids_free(&acl_ids);

      dmu_tx_commit(tx);

      zfs_dirent_unlock(dl);

      VN_RELE(ZTOV(zp));

      ZFS_EXIT(zfsvfs);
      return (error);
}

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

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zp);

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

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

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

      ASSERT(tdvp->v_type == VDIR);

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

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

      if (svp->v_vfsp != tdvp->v_vfsp) {
            ZFS_EXIT(zfsvfs);
            return (EXDEV);
      }
      szp = VTOZ(svp);
      ZFS_VERIFY_ZP(szp);

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

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

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

      owner = zfs_fuid_map_id(zfsvfs, szp->z_phys->zp_uid, cr, ZFS_OWNER);
      if (owner != crgetuid(cr) &&
          secpolicy_basic_link(cr) != 0) {
            ZFS_EXIT(zfsvfs);
            return (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_lock(&dl, dzp, name, &tzp, zf, NULL, NULL);
      if (error) {
            ZFS_EXIT(zfsvfs);
            return (error);
      }

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

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

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

      dmu_tx_commit(tx);

      zfs_dirent_unlock(dl);

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

      ZFS_EXIT(zfsvfs);
      return (error);
}

/*
 * zfs_null_putapage() is used when the file system has been force
 * unmounted. It just drops the pages.
 */
/* ARGSUSED */
/* ZFSFUSE: not used */
#if 0
static int
zfs_null_putapage(vnode_t *vp, page_t *pp, u_offset_t *offp,
            size_t *lenp, int flags, cred_t *cr)
{
      pvn_write_done(pp, B_INVAL|B_FORCE|B_ERROR);
      return (0);
}
#endif

/*
 * Push a page out to disk, klustering if possible.
 *
 *    IN:   vp    - file to push page to.
 *          pp    - page to push.
 *          flags - additional flags.
 *          cr    - credentials of caller.
 *
 *    OUT:  offp  - start of range pushed.
 *          lenp  - len of range pushed.
 *
 *    RETURN:     0 if success
 *          error code if failure
 *
 * NOTE: callers must have locked the page to be pushed.  On
 * exit, the page (and all other pages in the kluster) must be
 * unlocked.
 */
/* ARGSUSED */
/* ZFSFUSE: not used */
#if 0
static int
zfs_putapage(vnode_t *vp, page_t *pp, u_offset_t *offp,
            size_t *lenp, int flags, cred_t *cr)
{
      znode_t           *zp = VTOZ(vp);
      zfsvfs_t    *zfsvfs = zp->z_zfsvfs;
      dmu_tx_t    *tx;
      u_offset_t  off, koff;
      size_t            len, klen;
      uint64_t    filesz;
      int         err;

      filesz = zp->z_phys->zp_size;
      off = pp->p_offset;
      len = PAGESIZE;
      /*
       * If our blocksize is bigger than the page size, try to kluster
       * multiple pages so that we write a full block (thus avoiding
       * a read-modify-write).
       */
      if (off < filesz && zp->z_blksz > PAGESIZE) {
            klen = P2ROUNDUP((ulong_t)zp->z_blksz, PAGESIZE);
            koff = ISP2(klen) ? P2ALIGN(off, (u_offset_t)klen) : 0;
            ASSERT(koff <= filesz);
            if (koff + klen > filesz)
                  klen = P2ROUNDUP(filesz - koff, (uint64_t)PAGESIZE);
            pp = pvn_write_kluster(vp, pp, &off, &len, koff, klen, flags);
      }
      ASSERT3U(btop(len), ==, btopr(len));

      /*
       * Can't push pages past end-of-file.
       */
      if (off >= filesz) {
            /* ignore all pages */
            err = 0;
            goto out;
      } else if (off + len > filesz) {
            int npages = btopr(filesz - off);
            page_t *trunc;

            page_list_break(&pp, &trunc, npages);
            /* ignore pages past end of file */
            if (trunc)
                  pvn_write_done(trunc, flags);
            len = filesz - off;
      }

      if (zfs_usergroup_overquota(zfsvfs, B_FALSE, zp->z_phys->zp_uid) ||
          zfs_usergroup_overquota(zfsvfs, B_TRUE, zp->z_phys->zp_gid)) {
            err = EDQUOT;
            goto out;
      }
top:
      tx = dmu_tx_create(zfsvfs->z_os);
      dmu_tx_hold_write(tx, zp->z_id, off, len);
      dmu_tx_hold_bonus(tx, zp->z_id);
      err = dmu_tx_assign(tx, TXG_NOWAIT);
      if (err != 0) {
            if (err == ERESTART) {
                  dmu_tx_wait(tx);
                  dmu_tx_abort(tx);
                  goto top;
            }
            dmu_tx_abort(tx);
            goto out;
      }

      if (zp->z_blksz <= PAGESIZE) {
            caddr_t va = zfs_map_page(pp, S_READ);
            ASSERT3U(len, <=, PAGESIZE);
            dmu_write(zfsvfs->z_os, zp->z_id, off, len, va, tx);
            zfs_unmap_page(pp, va);
      } else {
            err = dmu_write_pages(zfsvfs->z_os, zp->z_id, off, len, pp, tx);
      }

      if (err == 0) {
            zfs_time_stamper(zp, CONTENT_MODIFIED, tx);
            zfs_log_write(zfsvfs->z_log, tx, TX_WRITE, zp, off, len, 0);
            dmu_tx_commit(tx);
      }

out:
      pvn_write_done(pp, (err ? B_ERROR : 0) | flags);
      if (offp)
            *offp = off;
      if (lenp)
            *lenp = len;

      return (err);
}
#endif

/*
 * Copy the portion of the file indicated from pages into the file.
 * The pages are stored in a page list attached to the files vnode.
 *
 *    IN:   vp    - vnode of file to push page data to.
 *          off   - position in file to put data.
 *          len   - amount of data to write.
 *          flags - flags to control the operation.
 *          cr    - credentials of caller.
 *          ct    - caller context.
 *
 *    RETURN:     0 if success
 *          error code if failure
 *
 * Timestamps:
 *    vp - ctime|mtime updated
 */
/*ARGSUSED*/
static int
zfs_putpage(vnode_t *vp, offset_t off, size_t len, int flags, cred_t *cr,
    caller_context_t *ct)
{
      /* ZFSFUSE: not used */
      abort();
#if 0
      znode_t           *zp = VTOZ(vp);
      zfsvfs_t    *zfsvfs = zp->z_zfsvfs;
      page_t            *pp;
      size_t            io_len;
      u_offset_t  io_off;
      uint_t            blksz;
      rl_t        *rl;
      int         error = 0;

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zp);

      /*
       * Align this request to the file block size in case we kluster.
       * XXX - this can result in pretty aggresive locking, which can
       * impact simultanious read/write access.  One option might be
       * to break up long requests (len == 0) into block-by-block
       * operations to get narrower locking.
       */
      blksz = zp->z_blksz;
      if (ISP2(blksz))
            io_off = P2ALIGN_TYPED(off, blksz, u_offset_t);
      else
            io_off = 0;
      if (len > 0 && ISP2(blksz))
            io_len = P2ROUNDUP_TYPED(len + (off - io_off), blksz, size_t);
      else
            io_len = 0;

      if (io_len == 0) {
            /*
             * Search the entire vp list for pages >= io_off.
             */
            rl = zfs_range_lock(zp, io_off, UINT64_MAX, RL_WRITER);
            error = pvn_vplist_dirty(vp, io_off, zfs_putapage, flags, cr);
            goto out;
      }
      rl = zfs_range_lock(zp, io_off, io_len, RL_WRITER);

      if (off > zp->z_phys->zp_size) {
            /* past end of file */
            zfs_range_unlock(rl);
            ZFS_EXIT(zfsvfs);
            return (0);
      }

      len = MIN(io_len, P2ROUNDUP(zp->z_phys->zp_size, PAGESIZE) - io_off);

      for (off = io_off; io_off < off + len; io_off += io_len) {
            if ((flags & B_INVAL) || ((flags & B_ASYNC) == 0)) {
                  pp = page_lookup(vp, io_off,
                      (flags & (B_INVAL | B_FREE)) ? SE_EXCL : SE_SHARED);
            } else {
                  pp = page_lookup_nowait(vp, io_off,
                      (flags & B_FREE) ? SE_EXCL : SE_SHARED);
            }

            if (pp != NULL && pvn_getdirty(pp, flags)) {
                  int err;

                  /*
                   * Found a dirty page to push
                   */
                  err = zfs_putapage(vp, pp, &io_off, &io_len, flags, cr);
                  if (err)
                        error = err;
            } else {
                  io_len = PAGESIZE;
            }
      }
out:
      zfs_range_unlock(rl);
      if ((flags & B_ASYNC) == 0)
            zil_commit(zfsvfs->z_log, UINT64_MAX, zp->z_id);
      ZFS_EXIT(zfsvfs);
      return (error);
#endif
}

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

      rw_enter(&zfsvfs->z_teardown_inactive_lock, RW_READER);
      if (zp->z_dbuf == NULL) {
            /*
             * The fs has been unmounted, or we did a
             * suspend/resume and this file no longer exists.
             */
            if (vn_has_cached_data(vp)) {
                  (void) pvn_vplist_dirty(vp, 0, zfs_null_putapage,
                      B_INVAL, cr);
            }

            mutex_enter(&zp->z_lock);
            vp->v_count = 0; /* count arrives as 1 */
            mutex_exit(&zp->z_lock);
            rw_exit(&zfsvfs->z_teardown_inactive_lock);
            zfs_znode_free(zp);
            return;
      }

      /*
       * Attempt to push any data in the page cache.  If this fails
       * we will get kicked out later in zfs_zinactive().
       */
      if (vn_has_cached_data(vp)) {
            (void) pvn_vplist_dirty(vp, 0, zfs_putapage, B_INVAL|B_ASYNC,
                cr);
      }

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

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

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

/*
 * Bounds-check the seek operation.
 *
 *    IN:   vp    - vnode seeking within
 *          ooff  - old file offset
 *          noffp - pointer to new file offset
 *          ct    - caller context
 *
 *    RETURN:     0 if success
 *          EINVAL if new offset invalid
 */
/* ARGSUSED */
static int
zfs_seek(vnode_t *vp, offset_t ooff, offset_t *noffp,
    caller_context_t *ct)
{
      if (vp->v_type == VDIR)
            return (0);
      return ((*noffp < 0 || *noffp > MAXOFFSET_T) ? EINVAL : 0);
}

/*
 * Pre-filter the generic locking function to trap attempts to place
 * a mandatory lock on a memory mapped file.
 */
static int
zfs_frlock(vnode_t *vp, int cmd, flock64_t *bfp, int flag, offset_t offset,
    flk_callback_t *flk_cbp, cred_t *cr, caller_context_t *ct)
{
      /* ZFSFUSE: not used */
      abort();
#if 0
      znode_t *zp = VTOZ(vp);
      zfsvfs_t *zfsvfs = zp->z_zfsvfs;
      int error;

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zp);

      /*
       * We are following the UFS semantics with respect to mapcnt
       * here: If we see that the file is mapped already, then we will
       * return an error, but we don't worry about races between this
       * function and zfs_map().
       */
      if (zp->z_mapcnt > 0 && MANDMODE((mode_t)zp->z_phys->zp_mode)) {
            ZFS_EXIT(zfsvfs);
            return (EAGAIN);
      }
      error = fs_frlock(vp, cmd, bfp, flag, offset, flk_cbp, cr, ct);
      ZFS_EXIT(zfsvfs);
      return (error);
#endif
}

/*
 * If we can't find a page in the cache, we will create a new page
 * and fill it with file data.  For efficiency, we may try to fill
 * multiple pages at once (klustering) to fill up the supplied page
 * list.  Note that the pages to be filled are held with an exclusive
 * lock to prevent access by other threads while they are being filled.
 */
/* ZFSFUSE: not implemented */
#if 0
static int
zfs_fillpage(vnode_t *vp, u_offset_t off, struct seg *seg,
    caddr_t addr, page_t *pl[], size_t plsz, enum seg_rw rw)
{
      znode_t *zp = VTOZ(vp);
      page_t *pp, *cur_pp;
      objset_t *os = zp->z_zfsvfs->z_os;
      u_offset_t io_off, total;
      size_t io_len;
      int err;

      if (plsz == PAGESIZE || zp->z_blksz <= PAGESIZE) {
            /*
             * We only have a single page, don't bother klustering
             */
            io_off = off;
            io_len = PAGESIZE;
            pp = page_create_va(vp, io_off, io_len,
                PG_EXCL | PG_WAIT, seg, addr);
      } else {
            /*
             * Try to find enough pages to fill the page list
             */
            pp = pvn_read_kluster(vp, off, seg, addr, &io_off,
                &io_len, off, plsz, 0);
      }
      if (pp == NULL) {
            /*
             * The page already exists, nothing to do here.
             */
            *pl = NULL;
            return (0);
      }

      /*
       * Fill the pages in the kluster.
       */
      cur_pp = pp;
      for (total = io_off + io_len; io_off < total; io_off += PAGESIZE) {
            caddr_t va;

            ASSERT3U(io_off, ==, cur_pp->p_offset);
            va = zfs_map_page(cur_pp, S_WRITE);
            err = dmu_read(os, zp->z_id, io_off, PAGESIZE, va,
                DMU_READ_PREFETCH);
            zfs_unmap_page(cur_pp, va);
            if (err) {
                  /* On error, toss the entire kluster */
                  pvn_read_done(pp, B_ERROR);
                  /* convert checksum errors into IO errors */
                  if (err == ECKSUM)
                        err = EIO;
                  return (err);
            }
            cur_pp = cur_pp->p_next;
      }

      /*
       * Fill in the page list array from the kluster starting
       * from the desired offset `off'.
       * NOTE: the page list will always be null terminated.
       */
      pvn_plist_init(pp, pl, plsz, off, io_len, rw);
      ASSERT(pl == NULL || (*pl)->p_offset == off);

      return (0);
}
#endif

/*
 * Return pointers to the pages for the file region [off, off + len]
 * in the pl array.  If plsz is greater than len, this function may
 * also return page pointers from after the specified region
 * (i.e. the region [off, off + plsz]).  These additional pages are
 * only returned if they are already in the cache, or were created as
 * part of a klustered read.
 *
 *    IN:   vp    - vnode of file to get data from.
 *          off   - position in file to get data from.
 *          len   - amount of data to retrieve.
 *          plsz  - length of provided page list.
 *          seg   - segment to obtain pages for.
 *          addr  - virtual address of fault.
 *          rw    - mode of created pages.
 *          cr    - credentials of caller.
 *          ct    - caller context.
 *
 *    OUT:  protp - protection mode of created pages.
 *          pl    - list of pages created.
 *
 *    RETURN:     0 if success
 *          error code if failure
 *
 * Timestamps:
 *    vp - atime updated
 */
/* ARGSUSED */
static int
zfs_getpage(vnode_t *vp, offset_t off, size_t len, uint_t *protp,
      page_t *pl[], size_t plsz, struct seg *seg, caddr_t addr,
      enum seg_rw rw, cred_t *cr, caller_context_t *ct)
{
      /* ZFSFUSE: not implemented */
      abort();
#if 0
      znode_t           *zp = VTOZ(vp);
      zfsvfs_t    *zfsvfs = zp->z_zfsvfs;
      page_t            **pl0 = pl;
      int         err = 0;

      /* we do our own caching, faultahead is unnecessary */
      if (pl == NULL)
            return (0);
      else if (len > plsz)
            len = plsz;
      else
            len = P2ROUNDUP(len, PAGESIZE);
      ASSERT(plsz >= len);

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zp);

      if (protp)
            *protp = PROT_ALL;

      /*
       * Loop through the requested range [off, off + len) looking
       * for pages.  If we don't find a page, we will need to create
       * a new page and fill it with data from the file.
       */
      while (len > 0) {
            if (*pl = page_lookup(vp, off, SE_SHARED))
                  *(pl+1) = NULL;
            else if (err = zfs_fillpage(vp, off, seg, addr, pl, plsz, rw))
                  goto out;
            while (*pl) {
                  ASSERT3U((*pl)->p_offset, ==, off);
                  off += PAGESIZE;
                  addr += PAGESIZE;
                  if (len > 0) {
                        ASSERT3U(len, >=, PAGESIZE);
                        len -= PAGESIZE;
                  }
                  ASSERT3U(plsz, >=, PAGESIZE);
                  plsz -= PAGESIZE;
                  pl++;
            }
      }

      /*
       * Fill out the page array with any pages already in the cache.
       */
      while (plsz > 0 &&
          (*pl++ = page_lookup_nowait(vp, off, SE_SHARED))) {
                  off += PAGESIZE;
                  plsz -= PAGESIZE;
      }
out:
      if (err) {
            /*
             * Release any pages we have previously locked.
             */
            while (pl > pl0)
                  page_unlock(*--pl);
      } else {
            ZFS_ACCESSTIME_STAMP(zfsvfs, zp);
      }

      *pl = NULL;

      ZFS_EXIT(zfsvfs);
      return (err);
#endif
}

/*
 * Request a memory map for a section of a file.  This code interacts
 * with common code and the VM system as follows:
 *
 *    common code calls mmap(), which ends up in smmap_common()
 *
 *    this calls VOP_MAP(), which takes you into (say) zfs
 *
 *    zfs_map() calls as_map(), passing segvn_create() as the callback
 *
 *    segvn_create() creates the new segment and calls VOP_ADDMAP()
 *
 *    zfs_addmap() updates z_mapcnt
 */
/*ARGSUSED*/
static int
zfs_map(vnode_t *vp, offset_t off, struct as *as, caddr_t *addrp,
    size_t len, uchar_t prot, uchar_t maxprot, uint_t flags, cred_t *cr,
    caller_context_t *ct)
{
      /* ZFSFUSE: not implemented */
      abort();
#if 0
      znode_t *zp = VTOZ(vp);
      zfsvfs_t *zfsvfs = zp->z_zfsvfs;
      segvn_crargs_t    vn_a;
      int         error;

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zp);

      if ((prot & PROT_WRITE) &&
          (zp->z_phys->zp_flags & (ZFS_IMMUTABLE | ZFS_READONLY |
          ZFS_APPENDONLY))) {
            ZFS_EXIT(zfsvfs);
            return (EPERM);
      }

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

      if (vp->v_flag & VNOMAP) {
            ZFS_EXIT(zfsvfs);
            return (ENOSYS);
      }

      if (off < 0 || len > MAXOFFSET_T - off) {
            ZFS_EXIT(zfsvfs);
            return (ENXIO);
      }

      if (vp->v_type != VREG) {
            ZFS_EXIT(zfsvfs);
            return (ENODEV);
      }

      /*
       * If file is locked, disallow mapping.
       */
      if (MANDMODE((mode_t)zp->z_phys->zp_mode) && vn_has_flocks(vp)) {
            ZFS_EXIT(zfsvfs);
            return (EAGAIN);
      }

      as_rangelock(as);
      error = choose_addr(as, addrp, len, off, ADDR_VACALIGN, flags);
      if (error != 0) {
            as_rangeunlock(as);
            ZFS_EXIT(zfsvfs);
            return (error);
      }

      vn_a.vp = vp;
      vn_a.offset = (u_offset_t)off;
      vn_a.type = flags & MAP_TYPE;
      vn_a.prot = prot;
      vn_a.maxprot = maxprot;
      vn_a.cred = cr;
      vn_a.amp = NULL;
      vn_a.flags = flags & ~MAP_TYPE;
      vn_a.szc = 0;
      vn_a.lgrp_mem_policy_flags = 0;

      error = as_map(as, *addrp, len, segvn_create, &vn_a);

      as_rangeunlock(as);
      ZFS_EXIT(zfsvfs);
      return (error);
#endif
}

/* ARGSUSED */
static int
zfs_addmap(vnode_t *vp, offset_t off, struct as *as, caddr_t addr,
    size_t len, uchar_t prot, uchar_t maxprot, uint_t flags, cred_t *cr,
    caller_context_t *ct)
{
      /* ZFSFUSE: not used */
      abort();
#if 0
      uint64_t pages = btopr(len);

      atomic_add_64(&VTOZ(vp)->z_mapcnt, pages);
      return (0);
#endif
}

/*
 * The reason we push dirty pages as part of zfs_delmap() is so that we get a
 * more accurate mtime for the associated file.  Since we don't have a way of
 * detecting when the data was actually modified, we have to resort to
 * heuristics.  If an explicit msync() is done, then we mark the mtime when the
 * last page is pushed.  The problem occurs when the msync() call is omitted,
 * which by far the most common case:
 *
 *    open()
 *    mmap()
 *    <modify memory>
 *    munmap()
 *    close()
 *    <time lapse>
 *    putpage() via fsflush
 *
 * If we wait until fsflush to come along, we can have a modification time that
 * is some arbitrary point in the future.  In order to prevent this in the
 * common case, we flush pages whenever a (MAP_SHARED, PROT_WRITE) mapping is
 * torn down.
 */
/* ARGSUSED */
static int
zfs_delmap(vnode_t *vp, offset_t off, struct as *as, caddr_t addr,
    size_t len, uint_t prot, uint_t maxprot, uint_t flags, cred_t *cr,
    caller_context_t *ct)
{
      /* ZFSFUSE: not used */
      abort();
#if 0
      uint64_t pages = btopr(len);

      ASSERT3U(VTOZ(vp)->z_mapcnt, >=, pages);
      atomic_add_64(&VTOZ(vp)->z_mapcnt, -pages);

      if ((flags & MAP_SHARED) && (prot & PROT_WRITE) &&
          vn_has_cached_data(vp))
            (void) VOP_PUTPAGE(vp, off, len, B_ASYNC, cr, ct);

      return (0);
#endif
}

/*
 * Free or allocate space in a file.  Currently, this function only
 * supports the `F_FREESP' command.  However, this command is somewhat
 * misnamed, as its functionality includes the ability to allocate as
 * well as free space.
 *
 *    IN:   vp    - vnode of file to free data in.
 *          cmd   - action to take (only F_FREESP supported).
 *          bfp   - section of file to free/alloc.
 *          flag  - current file open mode flags.
 *          offset      - current file offset.
 *          cr    - credentials of caller [UNUSED].
 *          ct    - caller context.
 *
 *    RETURN:     0 if success
 *          error code if failure
 *
 * Timestamps:
 *    vp - ctime|mtime updated
 */
/* ARGSUSED */
static int
zfs_space(vnode_t *vp, int cmd, flock64_t *bfp, int flag,
    offset_t offset, cred_t *cr, caller_context_t *ct)
{
      znode_t           *zp = VTOZ(vp);
      zfsvfs_t    *zfsvfs = zp->z_zfsvfs;
      uint64_t    off, len;
      int         error;

      ZFS_ENTER(zfsvfs);
      ZFS_VERIFY_ZP(zp);

      if (cmd != F_FREESP) {
            ZFS_EXIT(zfsvfs);
            return (EINVAL);
      }

      if (error = convoff(vp, bfp, 0, offset)) {
            ZFS_EXIT(zfsvfs);
            return (error);
      }

      if (bfp->l_len < 0) {
            ZFS_EXIT(zfsvfs);
            return (EINVAL);
      }

      off = bfp->l_start;
      len = bfp->l_len; /* 0 means from off to end of file */

      error = zfs_freesp(zp, off, len, flag, TRUE);

      ZFS_EXIT(zfsvfs);
      return (error);
}

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

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

      size = (zfsvfs->z_parent != zfsvfs) ? LONG_FID_LEN : SHORT_FID_LEN;
      if (fidp->fid_len < size) {
            fidp->fid_len = size;
            ZFS_EXIT(zfsvfs);
            return (ENOSPC);
      }

      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)
{
/* ZFSFUSE: not needed */
      abort();
#if 0
      znode_t           *zp, *xzp;
      zfsvfs_t    *zfsvfs;
      zfs_dirlock_t     *dl;
      int         error;

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

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

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

      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_ACL_ENABLED:
            *valp = _ACL_ACE_ENABLED;
            return (0);

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

      default:
            return (fs_pathconf(vp, cmd, valp, cr, ct));
      }
#endif
}

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

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

      return (error);
}

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

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

/*
 * Predeclare these here so that the compiler assumes that
 * this is an "old style" function declaration that does
 * not include arguments => we won't get type mismatch errors
 * in the initializations that follow.
 */
static int zfs_inval();
static int zfs_isdir();

static int
zfs_inval()
{
      return (EINVAL);
}

static int
zfs_isdir()
{
      return (EISDIR);
}


static int
zfs_getattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *cr,
    caller_context_t *ct);

static int
zfs_setattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *cr,
        caller_context_t *ct);

static int
zfs_rename(vnode_t *sdvp, char *snm, vnode_t *tdvp, char *tnm, cred_t *cr,
    caller_context_t *ct, int flags);

/*
 * Directory vnode operations template
 */
vnodeops_t *zfs_dvnodeops;
const fs_operation_def_t zfs_dvnodeops_template[] = {
      VOPNAME_OPEN,           { .vop_open = zfs_open },
      VOPNAME_CLOSE,          { .vop_close = zfs_close },
      VOPNAME_READ,           { .error = zfs_isdir },
      VOPNAME_WRITE,          { .error = zfs_isdir },
      VOPNAME_IOCTL,          { .vop_ioctl = zfs_ioctl },
      VOPNAME_GETATTR,  { .vop_getattr = zfs_getattr },
      VOPNAME_SETATTR,  { .vop_setattr = zfs_setattr },
      VOPNAME_ACCESS,         { .vop_access = zfs_access },
      VOPNAME_LOOKUP,         { .vop_lookup = zfs_lookup },
      VOPNAME_CREATE,         { .vop_create = zfs_create },
      VOPNAME_REMOVE,         { .vop_remove = zfs_remove },
      VOPNAME_LINK,           { .vop_link = zfs_link },
      VOPNAME_RENAME,         { .vop_rename = zfs_rename },
      VOPNAME_MKDIR,          { .vop_mkdir = zfs_mkdir },
      VOPNAME_RMDIR,          { .vop_rmdir = zfs_rmdir },
      VOPNAME_READDIR,  { .vop_readdir = zfs_readdir },
      VOPNAME_SYMLINK,  { .vop_symlink = zfs_symlink },
      VOPNAME_FSYNC,          { .vop_fsync = zfs_fsync },
      VOPNAME_INACTIVE, { .vop_inactive = zfs_inactive },
      VOPNAME_FID,            { .vop_fid = zfs_fid },
      VOPNAME_SEEK,           { .vop_seek = zfs_seek },
      VOPNAME_PATHCONF, { .vop_pathconf = zfs_pathconf },
      VOPNAME_GETSECATTR,     { .vop_getsecattr = zfs_getsecattr },
      VOPNAME_SETSECATTR,     { .vop_setsecattr = zfs_setsecattr },
      VOPNAME_VNEVENT,  { .vop_vnevent = fs_vnevent_support },
      NULL,             NULL
};

/*
 * Regular file vnode operations template
 */
vnodeops_t *zfs_fvnodeops;
const fs_operation_def_t zfs_fvnodeops_template[] = {
      VOPNAME_OPEN,           { .vop_open = zfs_open },
      VOPNAME_CLOSE,          { .vop_close = zfs_close },
      VOPNAME_READ,           { .vop_read = zfs_read },
      VOPNAME_WRITE,          { .vop_write = zfs_write },
      VOPNAME_IOCTL,          { .vop_ioctl = zfs_ioctl },
      VOPNAME_GETATTR,  { .vop_getattr = zfs_getattr },
      VOPNAME_SETATTR,  { .vop_setattr = zfs_setattr },
      VOPNAME_ACCESS,         { .vop_access = zfs_access },
      VOPNAME_LOOKUP,         { .vop_lookup = zfs_lookup },
      VOPNAME_RENAME,         { .vop_rename = zfs_rename },
      VOPNAME_FSYNC,          { .vop_fsync = zfs_fsync },
      VOPNAME_INACTIVE, { .vop_inactive = zfs_inactive },
      VOPNAME_FID,            { .vop_fid = zfs_fid },
      VOPNAME_SEEK,           { .vop_seek = zfs_seek },
      VOPNAME_FRLOCK,         { .vop_frlock = zfs_frlock },
      VOPNAME_SPACE,          { .vop_space = zfs_space },
      VOPNAME_GETPAGE,  { .vop_getpage = zfs_getpage },
      VOPNAME_PUTPAGE,  { .vop_putpage = zfs_putpage },
      VOPNAME_MAP,            { .vop_map = zfs_map },
      VOPNAME_ADDMAP,         { .vop_addmap = zfs_addmap },
      VOPNAME_DELMAP,         { .vop_delmap = zfs_delmap },
      VOPNAME_PATHCONF, { .vop_pathconf = zfs_pathconf },
      VOPNAME_GETSECATTR,     { .vop_getsecattr = zfs_getsecattr },
      VOPNAME_SETSECATTR,     { .vop_setsecattr = zfs_setsecattr },
      VOPNAME_VNEVENT,  { .vop_vnevent = fs_vnevent_support },
      NULL,             NULL
};

/*
 * Symbolic link vnode operations template
 */
vnodeops_t *zfs_symvnodeops;
const fs_operation_def_t zfs_symvnodeops_template[] = {
      VOPNAME_GETATTR,  { .vop_getattr = zfs_getattr },
      VOPNAME_SETATTR,  { .vop_setattr = zfs_setattr },
      VOPNAME_ACCESS,         { .vop_access = zfs_access },
      VOPNAME_RENAME,         { .vop_rename = zfs_rename },
      VOPNAME_READLINK, { .vop_readlink = zfs_readlink },
      VOPNAME_INACTIVE, { .vop_inactive = zfs_inactive },
      VOPNAME_FID,            { .vop_fid = zfs_fid },
      VOPNAME_PATHCONF, { .vop_pathconf = zfs_pathconf },
      VOPNAME_VNEVENT,  { .vop_vnevent = fs_vnevent_support },
      NULL,             NULL
};

/*
 * special share hidden files vnode operations template
 */
vnodeops_t *zfs_sharevnodeops;
const fs_operation_def_t zfs_sharevnodeops_template[] = {
      VOPNAME_GETATTR,  { .vop_getattr = zfs_getattr },
      VOPNAME_ACCESS,         { .vop_access = zfs_access },
      VOPNAME_INACTIVE, { .vop_inactive = zfs_inactive },
      VOPNAME_FID,            { .vop_fid = zfs_fid },
      VOPNAME_PATHCONF, { .vop_pathconf = zfs_pathconf },
      VOPNAME_GETSECATTR,     { .vop_getsecattr = zfs_getsecattr },
      VOPNAME_SETSECATTR,     { .vop_setsecattr = zfs_setsecattr },
      VOPNAME_VNEVENT,  { .vop_vnevent = fs_vnevent_support },
      NULL,             NULL
};

/*
 * Extended attribute directory vnode operations template
 *    This template is identical to the directory vnodes
 *    operation template except for restricted operations:
 *          VOP_MKDIR()
 *          VOP_SYMLINK()
 * Note that there are other restrictions embedded in:
 *    zfs_create()      - restrict type to VREG
 *    zfs_link()  - no links into/out of attribute space
 *    zfs_rename()      - no moves into/out of attribute space
 */
vnodeops_t *zfs_xdvnodeops;
const fs_operation_def_t zfs_xdvnodeops_template[] = {
      VOPNAME_OPEN,           { .vop_open = zfs_open },
      VOPNAME_CLOSE,          { .vop_close = zfs_close },
      VOPNAME_IOCTL,          { .vop_ioctl = zfs_ioctl },
      VOPNAME_GETATTR,  { .vop_getattr = zfs_getattr },
      VOPNAME_SETATTR,  { .vop_setattr = zfs_setattr },
      VOPNAME_ACCESS,         { .vop_access = zfs_access },
      VOPNAME_LOOKUP,         { .vop_lookup = zfs_lookup },
      VOPNAME_CREATE,         { .vop_create = zfs_create },
      VOPNAME_REMOVE,         { .vop_remove = zfs_remove },
      VOPNAME_LINK,           { .vop_link = zfs_link },
      VOPNAME_RENAME,         { .vop_rename = zfs_rename },
      VOPNAME_MKDIR,          { .error = zfs_inval },
      VOPNAME_RMDIR,          { .vop_rmdir = zfs_rmdir },
      VOPNAME_READDIR,  { .vop_readdir = zfs_readdir },
      VOPNAME_SYMLINK,  { .error = zfs_inval },
      VOPNAME_FSYNC,          { .vop_fsync = zfs_fsync },
      VOPNAME_INACTIVE, { .vop_inactive = zfs_inactive },
      VOPNAME_FID,            { .vop_fid = zfs_fid },
      VOPNAME_SEEK,           { .vop_seek = zfs_seek },
      VOPNAME_PATHCONF, { .vop_pathconf = zfs_pathconf },
      VOPNAME_GETSECATTR,     { .vop_getsecattr = zfs_getsecattr },
      VOPNAME_SETSECATTR,     { .vop_setsecattr = zfs_setsecattr },
      VOPNAME_VNEVENT,  { .vop_vnevent = fs_vnevent_support },
      NULL,             NULL
};

/*
 * Error vnode operations template
 */
vnodeops_t *zfs_evnodeops;
const fs_operation_def_t zfs_evnodeops_template[] = {
      VOPNAME_INACTIVE, { .vop_inactive = zfs_inactive },
      VOPNAME_PATHCONF, { .vop_pathconf = zfs_pathconf },
      NULL,             NULL
};

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