text: /*
   * Copyright (c) 1989, 1993
   *	The Regents of the University of California.  All rights reserved.
   * (c) UNIX System Laboratories, Inc.
   * All or some portions of this file are derived from material licensed
   * to the University of California by American Telephone and Telegraph
   * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   * the permission of UNIX System Laboratories, Inc.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   *	@(#)vfs_subr.c	8.31 (Berkeley) 5/26/95
   * $FreeBSD: src/sys/kern/vfs_subr.c,v 1.249.2.30 2003/04/04 20:35:57 tegge Exp $
   */
  
  /*
   * External virtual filesystem routines
   */
  #include "opt_ddb.h"
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/buf.h>
  #include <sys/conf.h>
  #include <sys/dirent.h>
  #include <sys/domain.h>
  #include <sys/eventhandler.h>
  #include <sys/fcntl.h>
  #include <sys/file.h>
  #include <sys/kernel.h>
  #include <sys/kthread.h>
  #include <sys/malloc.h>
  #include <sys/mbuf.h>
  #include <sys/mount.h>
  #include <sys/priv.h>
  #include <sys/proc.h>
  #include <sys/reboot.h>
  #include <sys/socket.h>
  #include <sys/stat.h>
  #include <sys/sysctl.h>
  #include <sys/syslog.h>
  #include <sys/unistd.h>
  #include <sys/vmmeter.h>
  #include <sys/vnode.h>
  
  #include <machine/limits.h>
  
  #include <vm/vm.h>
  #include <vm/vm_object.h>
  #include <vm/vm_extern.h>
  #include <vm/vm_kern.h>
  #include <vm/pmap.h>
  #include <vm/vm_map.h>
  #include <vm/vm_page.h>
  #include <vm/vm_pager.h>
  #include <vm/vnode_pager.h>
  #include <vm/vm_zone.h>
  
  #include <sys/buf2.h>
  #include <sys/thread2.h>
  #include <sys/sysref2.h>
  #include <sys/mplock2.h>
  
  static MALLOC_DEFINE(M_NETADDR, "Export Host", "Export host address structure");
  
  int numvnodes;
  SYSCTL_INT(_debug, OID_AUTO, numvnodes, CTLFLAG_RD, &numvnodes, 0,
      "Number of vnodes allocated");
  int verbose_reclaims;
  SYSCTL_INT(_debug, OID_AUTO, verbose_reclaims, CTLFLAG_RD, &verbose_reclaims, 0,
      "Output filename of reclaimed vnode(s)");
  
  enum vtype iftovt_tab[16] = {
  	VNON, VFIFO, VCHR, VNON, VDIR, VNON, VBLK, VNON,
  	VREG, VNON, VLNK, VNON, VSOCK, VNON, VNON, VBAD,
  };
  int vttoif_tab[9] = {
  	0, S_IFREG, S_IFDIR, S_IFBLK, S_IFCHR, S_IFLNK,
  	S_IFSOCK, S_IFIFO, S_IFMT,
  };
  
  static int reassignbufcalls;
  SYSCTL_INT(_vfs, OID_AUTO, reassignbufcalls, CTLFLAG_RW, &reassignbufcalls,
      0, "Number of times buffers have been reassigned to the proper list");
  
  static int check_buf_overlap = 2;	/* invasive check */
  SYSCTL_INT(_vfs, OID_AUTO, check_buf_overlap, CTLFLAG_RW, &check_buf_overlap,
      0, "Enable overlapping buffer checks");
  
  int	nfs_mount_type = -1;
  static struct lwkt_token spechash_token;
  struct nfs_public nfs_pub;	/* publicly exported FS */
  
  int desiredvnodes;
  SYSCTL_INT(_kern, KERN_MAXVNODES, maxvnodes, CTLFLAG_RW, 
  		&desiredvnodes, 0, "Maximum number of vnodes");
  
  static void	vfs_free_addrlist (struct netexport *nep);
  static int	vfs_free_netcred (struct radix_node *rn, void *w);
  static int	vfs_hang_addrlist (struct mount *mp, struct netexport *nep,
  				       const struct export_args *argp);
  
  /*
   * Red black tree functions
   */
  static int rb_buf_compare(struct buf *b1, struct buf *b2);
  RB_GENERATE2(buf_rb_tree, buf, b_rbnode, rb_buf_compare, off_t, b_loffset);
  RB_GENERATE2(buf_rb_hash, buf, b_rbhash, rb_buf_compare, off_t, b_loffset);
  
  static int
  rb_buf_compare(struct buf *b1, struct buf *b2)
  {
  	if (b1->b_loffset < b2->b_loffset)
  		return(-1);
  	if (b1->b_loffset > b2->b_loffset)
  		return(1);
  	return(0);
  }
  
  /*
   * Returns non-zero if the vnode is a candidate for lazy msyncing.
   *
   * NOTE: v_object is not stable (this scan can race), however the
   *	 mntvnodescan code holds vmobj_token so any VM object we
   *	 do find will remain stable storage.
   */
  static __inline int
  vshouldmsync(struct vnode *vp)
  {
  	vm_object_t object;
  
  	if (vp->v_auxrefs != 0 || vp->v_sysref.refcnt > 0)
  		return (0);		/* other holders */
  	object = vp->v_object;
  	cpu_ccfence();
  	if (object && (object->ref_count || object->resident_page_count))
  		return(0);
  	return (1);
  }
  
  /*
   * Initialize the vnode management data structures. 
   *
   * Called from vfsinit()
   */
  void
  vfs_subr_init(void)
  {
  	int factor1;
  	int factor2;
  
  	/*
  	 * Desiredvnodes is kern.maxvnodes.  We want to scale it 
  	 * according to available system memory but we may also have
  	 * to limit it based on available KVM, which is capped on 32 bit
  	 * systems, to ~80K vnodes or so.
  	 *
  	 * WARNING!  For machines with 64-256M of ram we have to be sure
  	 *	     that the default limit scales down well due to HAMMER
  	 *	     taking up significantly more memory per-vnode vs UFS.
  	 *	     We want around ~5800 on a 128M machine.
  	 */
  	factor1 = 20 * (sizeof(struct vm_object) + sizeof(struct vnode));
  	factor2 = 25 * (sizeof(struct vm_object) + sizeof(struct vnode));
  	desiredvnodes =
  		imin((int64_t)vmstats.v_page_count * PAGE_SIZE / factor1,
  		     KvaSize / factor2);
  	desiredvnodes = imax(desiredvnodes, maxproc * 8);
  
  	lwkt_token_init(&spechash_token, "spechash");
  }
  
  /*
   * Knob to control the precision of file timestamps:
   *
   *   0 = seconds only; nanoseconds zeroed.
   *   1 = seconds and nanoseconds, accurate within 1/HZ.
   *   2 = seconds and nanoseconds, truncated to microseconds.
   * >=3 = seconds and nanoseconds, maximum precision.
   */
  enum { TSP_SEC, TSP_HZ, TSP_USEC, TSP_NSEC };
  
  static int timestamp_precision = TSP_SEC;
  SYSCTL_INT(_vfs, OID_AUTO, timestamp_precision, CTLFLAG_RW,
  		&timestamp_precision, 0, "Precision of file timestamps");
  
  /*
   * Get a current timestamp.
   *
   * MPSAFE
   */
  void
  vfs_timestamp(struct timespec *tsp)
  {
  	struct timeval tv;
  
  	switch (timestamp_precision) {
  	case TSP_SEC:
  		tsp->tv_sec = time_second;
  		tsp->tv_nsec = 0;
  		break;
  	case TSP_HZ:
  		getnanotime(tsp);
  		break;
  	case TSP_USEC:
  		microtime(&tv);
  		TIMEVAL_TO_TIMESPEC(&tv, tsp);
  		break;
  	case TSP_NSEC:
  	default:
  		nanotime(tsp);
  		break;
  	}
  }
  
  /*
   * Set vnode attributes to VNOVAL
   */
  void
  vattr_null(struct vattr *vap)
  {
  	vap->va_type = VNON;
  	vap->va_size = VNOVAL;
  	vap->va_bytes = VNOVAL;
  	vap->va_mode = VNOVAL;
  	vap->va_nlink = VNOVAL;
  	vap->va_uid = VNOVAL;
  	vap->va_gid = VNOVAL;
  	vap->va_fsid = VNOVAL;
  	vap->va_fileid = VNOVAL;
  	vap->va_blocksize = VNOVAL;
  	vap->va_rmajor = VNOVAL;
  	vap->va_rminor = VNOVAL;
  	vap->va_atime.tv_sec = VNOVAL;
  	vap->va_atime.tv_nsec = VNOVAL;
  	vap->va_mtime.tv_sec = VNOVAL;
  	vap->va_mtime.tv_nsec = VNOVAL;
  	vap->va_ctime.tv_sec = VNOVAL;
  	vap->va_ctime.tv_nsec = VNOVAL;
  	vap->va_flags = VNOVAL;
  	vap->va_gen = VNOVAL;
  	vap->va_vaflags = 0;
  	/* va_*_uuid fields are only valid if related flags are set */
  }
  
  /*
   * Flush out and invalidate all buffers associated with a vnode.
   *
   * vp must be locked.
   */
  static int vinvalbuf_bp(struct buf *bp, void *data);
  
  struct vinvalbuf_bp_info {
  	struct vnode *vp;
  	int slptimeo;
  	int lkflags;
  	int flags;
  	int clean;
  };
  
  int
  vinvalbuf(struct vnode *vp, int flags, int slpflag, int slptimeo)
  {
  	struct vinvalbuf_bp_info info;
  	vm_object_t object;
  	int error;
  
  	lwkt_gettoken(&vp->v_token);
  
  	/*
  	 * If we are being asked to save, call fsync to ensure that the inode
  	 * is updated.
  	 */
  	if (flags & V_SAVE) {
  		error = bio_track_wait(&vp->v_track_write, slpflag, slptimeo);
  		if (error)
  			goto done;
  		if (!RB_EMPTY(&vp->v_rbdirty_tree)) {
  			if ((error = VOP_FSYNC(vp, MNT_WAIT, 0)) != 0)
  				goto done;
  #if 0
  			/*
  			 * Dirty bufs may be left or generated via races
  			 * in circumstances where vinvalbuf() is called on
  			 * a vnode not undergoing reclamation.   Only
  			 * panic if we are trying to reclaim the vnode.
  			 */
  			if ((vp->v_flag & VRECLAIMED) &&
  			    (bio_track_active(&vp->v_track_write) ||
  			    !RB_EMPTY(&vp->v_rbdirty_tree))) {
  				panic("vinvalbuf: dirty bufs");
  			}
  #endif
  		}
    	}
  	info.slptimeo = slptimeo;
  	info.lkflags = LK_EXCLUSIVE | LK_SLEEPFAIL;
  	if (slpflag & PCATCH)
  		info.lkflags |= LK_PCATCH;
  	info.flags = flags;
  	info.vp = vp;
  
  	/*
  	 * Flush the buffer cache until nothing is left, wait for all I/O
  	 * to complete.  At least one pass is required.  We might block
  	 * in the pip code so we have to re-check.  Order is important.
  	 */
  	do {
  		/*
  		 * Flush buffer cache
  		 */
  		if (!RB_EMPTY(&vp->v_rbclean_tree)) {
  			info.clean = 1;
  			error = RB_SCAN(buf_rb_tree, &vp->v_rbclean_tree,
  					NULL, vinvalbuf_bp, &info);
  		}
  		if (!RB_EMPTY(&vp->v_rbdirty_tree)) {
  			info.clean = 0;
  			error = RB_SCAN(buf_rb_tree, &vp->v_rbdirty_tree,
  					NULL, vinvalbuf_bp, &info);
  		}
  
  		/*
  		 * Wait for I/O completion.
  		 */
  		bio_track_wait(&vp->v_track_write, 0, 0);
  		if ((object = vp->v_object) != NULL)
  			refcount_wait(&object->paging_in_progress, "vnvlbx");
  	} while (bio_track_active(&vp->v_track_write) ||
  		 !RB_EMPTY(&vp->v_rbclean_tree) ||
  		 !RB_EMPTY(&vp->v_rbdirty_tree));
  
  	/*
  	 * Destroy the copy in the VM cache, too.
  	 */
  	if ((object = vp->v_object) != NULL) {
  		vm_object_page_remove(object, 0, 0,
  			(flags & V_SAVE) ? TRUE : FALSE);
  	}
  
  	if (!RB_EMPTY(&vp->v_rbdirty_tree) || !RB_EMPTY(&vp->v_rbclean_tree))
  		panic("vinvalbuf: flush failed");
  	if (!RB_EMPTY(&vp->v_rbhash_tree))
  		panic("vinvalbuf: flush failed, buffers still present");
  	error = 0;
  done:
  	lwkt_reltoken(&vp->v_token);
  	return (error);
  }
  
  static int
  vinvalbuf_bp(struct buf *bp, void *data)
  {
  	struct vinvalbuf_bp_info *info = data;
  	int error;
  
  	if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
  		atomic_add_int(&bp->b_refs, 1);
  		error = BUF_TIMELOCK(bp, info->lkflags,
  				     "vinvalbuf", info->slptimeo);
  		atomic_subtract_int(&bp->b_refs, 1);
  		if (error == 0) {
  			BUF_UNLOCK(bp);
  			error = ENOLCK;
  		}
  		if (error == ENOLCK)
  			return(0);
  		return (-error);
  	}
  	KKASSERT(bp->b_vp == info->vp);
  
  	/*
  	 * Must check clean/dirty status after successfully locking as
  	 * it may race.
  	 */
  	if ((info->clean && (bp->b_flags & B_DELWRI)) ||
  	    (info->clean == 0 && (bp->b_flags & B_DELWRI) == 0)) {
  		BUF_UNLOCK(bp);
  		return(0);
  	}
  
  	/*
  	 * NOTE:  NO B_LOCKED CHECK.  Also no buf_checkwrite()
  	 * check.  This code will write out the buffer, period.
  	 */
  	bremfree(bp);
  	if (((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI) &&
  	    (info->flags & V_SAVE)) {
  		cluster_awrite(bp);
  	} else if (info->flags & V_SAVE) {
  		/*
  		 * Cannot set B_NOCACHE on a clean buffer as this will
  		 * destroy the VM backing store which might actually
  		 * be dirty (and unsynchronized).
  		 */
  		bp->b_flags |= (B_INVAL | B_RELBUF);
  		brelse(bp);
  	} else {
  		bp->b_flags |= (B_INVAL | B_NOCACHE | B_RELBUF);
  		brelse(bp);
  	}
  	return(0);
  }
  
  /*
   * Truncate a file's buffer and pages to a specified length.  This
   * is in lieu of the old vinvalbuf mechanism, which performed unneeded
   * sync activity.
   *
   * The vnode must be locked.
   */
  static int vtruncbuf_bp_trunc_cmp(struct buf *bp, void *data);
  static int vtruncbuf_bp_trunc(struct buf *bp, void *data);
  static int vtruncbuf_bp_metasync_cmp(struct buf *bp, void *data);
  static int vtruncbuf_bp_metasync(struct buf *bp, void *data);
  
  struct vtruncbuf_info {
  	struct vnode *vp;
  	off_t	truncloffset;
  	int	clean;
  };
  
  int
  vtruncbuf(struct vnode *vp, off_t length, int blksize)
  {
  	struct vtruncbuf_info info;
  	const char *filename;
  	int count;
  
  	/*
  	 * Round up to the *next* block, then destroy the buffers in question.  
  	 * Since we are only removing some of the buffers we must rely on the
  	 * scan count to determine whether a loop is necessary.
  	 */
  	if ((count = (int)(length % blksize)) != 0)
  		info.truncloffset = length + (blksize - count);
  	else
  		info.truncloffset = length;
  	info.vp = vp;
  
  	lwkt_gettoken(&vp->v_token);
  	do {
  		info.clean = 1;
  		count = RB_SCAN(buf_rb_tree, &vp->v_rbclean_tree, 
  				vtruncbuf_bp_trunc_cmp,
  				vtruncbuf_bp_trunc, &info);
  		info.clean = 0;
  		count += RB_SCAN(buf_rb_tree, &vp->v_rbdirty_tree,
  				vtruncbuf_bp_trunc_cmp,
  				vtruncbuf_bp_trunc, &info);
  	} while(count);
  
  	/*
  	 * For safety, fsync any remaining metadata if the file is not being
  	 * truncated to 0.  Since the metadata does not represent the entire
  	 * dirty list we have to rely on the hit count to ensure that we get
  	 * all of it.
  	 */
  	if (length > 0) {
  		do {
  			count = RB_SCAN(buf_rb_tree, &vp->v_rbdirty_tree,
  					vtruncbuf_bp_metasync_cmp,
  					vtruncbuf_bp_metasync, &info);
  		} while (count);
  	}
  
  	/*
  	 * Clean out any left over VM backing store.
  	 *
  	 * It is possible to have in-progress I/O from buffers that were
  	 * not part of the truncation.  This should not happen if we
  	 * are truncating to 0-length.
  	 */
  	vnode_pager_setsize(vp, length);
  	bio_track_wait(&vp->v_track_write, 0, 0);
  
  	/*
  	 * Debugging only
  	 */
  	spin_lock(&vp->v_spin);
  	filename = TAILQ_FIRST(&vp->v_namecache) ?
  		   TAILQ_FIRST(&vp->v_namecache)->nc_name : "?";
  	spin_unlock(&vp->v_spin);
  
  	/*
  	 * Make sure no buffers were instantiated while we were trying
  	 * to clean out the remaining VM pages.  This could occur due
  	 * to busy dirty VM pages being flushed out to disk.
  	 */
  	do {
  		info.clean = 1;
  		count = RB_SCAN(buf_rb_tree, &vp->v_rbclean_tree, 
  				vtruncbuf_bp_trunc_cmp,
  				vtruncbuf_bp_trunc, &info);
  		info.clean = 0;
  		count += RB_SCAN(buf_rb_tree, &vp->v_rbdirty_tree,
  				vtruncbuf_bp_trunc_cmp,
  				vtruncbuf_bp_trunc, &info);
  		if (count) {
  			kprintf("Warning: vtruncbuf():  Had to re-clean %d "
  			       "left over buffers in %s\n", count, filename);
  		}
  	} while(count);
  
  	lwkt_reltoken(&vp->v_token);
  
  	return (0);
  }
  
  /*
   * The callback buffer is beyond the new file EOF and must be destroyed.
   * Note that the compare function must conform to the RB_SCAN's requirements.
   */
  static
  int
  vtruncbuf_bp_trunc_cmp(struct buf *bp, void *data)
  {
  	struct vtruncbuf_info *info = data;
  
  	if (bp->b_loffset >= info->truncloffset)
  		return(0);
  	return(-1);
  }
  
  static 
  int 
  vtruncbuf_bp_trunc(struct buf *bp, void *data)
  {
  	struct vtruncbuf_info *info = data;
  
  	/*
  	 * Do not try to use a buffer we cannot immediately lock, but sleep
  	 * anyway to prevent a livelock.  The code will loop until all buffers
  	 * can be acted upon.
  	 *
  	 * We must always revalidate the buffer after locking it to deal
  	 * with MP races.
  	 */
  	if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
  		atomic_add_int(&bp->b_refs, 1);
  		if (BUF_LOCK(bp, LK_EXCLUSIVE|LK_SLEEPFAIL) == 0)
  			BUF_UNLOCK(bp);
  		atomic_subtract_int(&bp->b_refs, 1);
  	} else if ((info->clean && (bp->b_flags & B_DELWRI)) ||
  		   (info->clean == 0 && (bp->b_flags & B_DELWRI) == 0) ||
  		   bp->b_vp != info->vp ||
  		   vtruncbuf_bp_trunc_cmp(bp, data)) {
  		BUF_UNLOCK(bp);
  	} else {
  		bremfree(bp);
  		bp->b_flags |= (B_INVAL | B_RELBUF | B_NOCACHE);
  		brelse(bp);
  	}
  	return(1);
  }
  
  /*
   * Fsync all meta-data after truncating a file to be non-zero.  Only metadata
   * blocks (with a negative loffset) are scanned.
   * Note that the compare function must conform to the RB_SCAN's requirements.
   */
  static int
  vtruncbuf_bp_metasync_cmp(struct buf *bp, void *data __unused)
  {
  	if (bp->b_loffset < 0)
  		return(0);
  	return(1);
  }
  
  static int
  vtruncbuf_bp_metasync(struct buf *bp, void *data)
  {
  	struct vtruncbuf_info *info = data;
  
  	if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
  		atomic_add_int(&bp->b_refs, 1);
  		if (BUF_LOCK(bp, LK_EXCLUSIVE|LK_SLEEPFAIL) == 0)
  			BUF_UNLOCK(bp);
  		atomic_subtract_int(&bp->b_refs, 1);
  	} else if ((bp->b_flags & B_DELWRI) == 0 ||
  		   bp->b_vp != info->vp ||
  		   vtruncbuf_bp_metasync_cmp(bp, data)) {
  		BUF_UNLOCK(bp);
  	} else {
  		bremfree(bp);
  		if (bp->b_vp == info->vp)
  			bawrite(bp);
  		else
  			bwrite(bp);
  	}
  	return(1);
  }
  
  /*
   * vfsync - implements a multipass fsync on a file which understands
   * dependancies and meta-data.  The passed vnode must be locked.  The 
   * waitfor argument may be MNT_WAIT or MNT_NOWAIT, or MNT_LAZY.
   *
   * When fsyncing data asynchronously just do one consolidated pass starting
   * with the most negative block number.  This may not get all the data due
   * to dependancies.
   *
   * When fsyncing data synchronously do a data pass, then a metadata pass,
   * then do additional data+metadata passes to try to get all the data out.
   */
  static int vfsync_wait_output(struct vnode *vp, 
  			    int (*waitoutput)(struct vnode *, struct thread *));
  static int vfsync_dummy_cmp(struct buf *bp __unused, void *data __unused);
  static int vfsync_data_only_cmp(struct buf *bp, void *data);
  static int vfsync_meta_only_cmp(struct buf *bp, void *data);
  static int vfsync_lazy_range_cmp(struct buf *bp, void *data);
  static int vfsync_bp(struct buf *bp, void *data);
  
  struct vfsync_info {
  	struct vnode *vp;
  	int synchronous;
  	int syncdeps;
  	int lazycount;
  	int lazylimit;
  	int skippedbufs;
  	int (*checkdef)(struct buf *);
  	int (*cmpfunc)(struct buf *, void *);
  };
  
  int
  vfsync(struct vnode *vp, int waitfor, int passes,
  	int (*checkdef)(struct buf *),
  	int (*waitoutput)(struct vnode *, struct thread *))
  {
  	struct vfsync_info info;
  	int error;
  
  	bzero(&info, sizeof(info));
  	info.vp = vp;
  	if ((info.checkdef = checkdef) == NULL)
  		info.syncdeps = 1;
  
  	lwkt_gettoken(&vp->v_token);
  
  	switch(waitfor) {
  	case MNT_LAZY | MNT_NOWAIT:
  	case MNT_LAZY:
  		/*
  		 * Lazy (filesystem syncer typ) Asynchronous plus limit the
  		 * number of data (not meta) pages we try to flush to 1MB.
  		 * A non-zero return means that lazy limit was reached.
  		 */
  		info.lazylimit = 1024 * 1024;
  		info.syncdeps = 1;
  		info.cmpfunc = vfsync_lazy_range_cmp;
  		error = RB_SCAN(buf_rb_tree, &vp->v_rbdirty_tree, 
  				vfsync_lazy_range_cmp, vfsync_bp, &info);
  		info.cmpfunc = vfsync_meta_only_cmp;
  		RB_SCAN(buf_rb_tree, &vp->v_rbdirty_tree, 
  			vfsync_meta_only_cmp, vfsync_bp, &info);
  		if (error == 0)
  			vp->v_lazyw = 0;
  		else if (!RB_EMPTY(&vp->v_rbdirty_tree))
  			vn_syncer_add(vp, 1);
  		error = 0;
  		break;
  	case MNT_NOWAIT:
  		/*
  		 * Asynchronous.  Do a data-only pass and a meta-only pass.
  		 */
  		info.syncdeps = 1;
  		info.cmpfunc = vfsync_data_only_cmp;
  		RB_SCAN(buf_rb_tree, &vp->v_rbdirty_tree, vfsync_data_only_cmp, 
  			vfsync_bp, &info);
  		info.cmpfunc = vfsync_meta_only_cmp;
  		RB_SCAN(buf_rb_tree, &vp->v_rbdirty_tree, vfsync_meta_only_cmp, 
  			vfsync_bp, &info);
  		error = 0;
  		break;
  	default:
  		/*
  		 * Synchronous.  Do a data-only pass, then a meta-data+data
  		 * pass, then additional integrated passes to try to get
  		 * all the dependancies flushed.
  		 */
  		info.cmpfunc = vfsync_data_only_cmp;
  		RB_SCAN(buf_rb_tree, &vp->v_rbdirty_tree, vfsync_data_only_cmp,
  			vfsync_bp, &info);
  		error = vfsync_wait_output(vp, waitoutput);
  		if (error == 0) {
  			info.skippedbufs = 0;
  			info.cmpfunc = vfsync_dummy_cmp;
  			RB_SCAN(buf_rb_tree, &vp->v_rbdirty_tree, NULL,
  				vfsync_bp, &info);
  			error = vfsync_wait_output(vp, waitoutput);
  			if (info.skippedbufs) {
  				kprintf("Warning: vfsync skipped %d dirty "
  					"bufs in pass2!\n", info.skippedbufs);
  			}
  		}
  		while (error == 0 && passes > 0 &&
  		       !RB_EMPTY(&vp->v_rbdirty_tree)
  		) {
  			if (--passes == 0) {
  				info.synchronous = 1;
  				info.syncdeps = 1;
  			}
  			info.cmpfunc = vfsync_dummy_cmp;
  			error = RB_SCAN(buf_rb_tree, &vp->v_rbdirty_tree, NULL,
  					vfsync_bp, &info);
  			if (error < 0)
  				error = -error;
  			info.syncdeps = 1;
  			if (error == 0)
  				error = vfsync_wait_output(vp, waitoutput);
  		}
  		break;
  	}
  	lwkt_reltoken(&vp->v_token);
  	return(error);
  }
  
  static int
  vfsync_wait_output(struct vnode *vp,
  		   int (*waitoutput)(struct vnode *, struct thread *))
  {
  	int error;
  
  	error = bio_track_wait(&vp->v_track_write, 0, 0);
  	if (waitoutput)
  		error = waitoutput(vp, curthread);
  	return(error);
  }
  
  static int
  vfsync_dummy_cmp(struct buf *bp __unused, void *data __unused)
  {
  	return(0);
  }
  
  static int
  vfsync_data_only_cmp(struct buf *bp, void *data)
  {
  	if (bp->b_loffset < 0)
  		return(-1);
  	return(0);
  }
  
  static int
  vfsync_meta_only_cmp(struct buf *bp, void *data)
  {
  	if (bp->b_loffset < 0)
  		return(0);
  	return(1);
  }
  
  static int
  vfsync_lazy_range_cmp(struct buf *bp, void *data)
  {
  	struct vfsync_info *info = data;
  
  	if (bp->b_loffset < info->vp->v_lazyw)
  		return(-1);
  	return(0);
  }
  
  static int
  vfsync_bp(struct buf *bp, void *data)
  {
  	struct vfsync_info *info = data;
  	struct vnode *vp = info->vp;
  	int error;
  
  	/*
  	 * Ignore buffers that we cannot immediately lock.
  	 */
  	if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
  		++info->skippedbufs;
  		return(0);
  	}
  
  	/*
  	 * We must revalidate the buffer after locking.
  	 */
  	if ((bp->b_flags & B_DELWRI) == 0 ||
  	    bp->b_vp != info->vp ||
  	    info->cmpfunc(bp, data)) {
  		BUF_UNLOCK(bp);
  		return(0);
  	}
  
  	/*
  	 * If syncdeps is not set we do not try to write buffers which have
  	 * dependancies.
  	 */
  	if (!info->synchronous && info->syncdeps == 0 && info->checkdef(bp)) {
  		BUF_UNLOCK(bp);
  		return(0);
  	}
  
  	/*
  	 * B_NEEDCOMMIT (primarily used by NFS) is a state where the buffer
  	 * has been written but an additional handshake with the device
  	 * is required before we can dispose of the buffer.  We have no idea
  	 * how to do this so we have to skip these buffers.
  	 */
  	if (bp->b_flags & B_NEEDCOMMIT) {
  		BUF_UNLOCK(bp);
  		return(0);
  	}
  
  	/*
  	 * Ask bioops if it is ok to sync.  If not the VFS may have
  	 * set B_LOCKED so we have to cycle the buffer.
  	 */
  	if (LIST_FIRST(&bp->b_dep) != NULL && buf_checkwrite(bp)) {
  		bremfree(bp);
  		brelse(bp);
  		return(0);
  	}
  
  	if (info->synchronous) {
  		/*
  		 * Synchronous flushing.  An error may be returned.
  		 */
  		bremfree(bp);
  		error = bwrite(bp);
  	} else { 
  		/*
  		 * Asynchronous flushing.  A negative return value simply
  		 * stops the scan and is not considered an error.  We use
  		 * this to support limited MNT_LAZY flushes.
  		 */
  		vp->v_lazyw = bp->b_loffset;
  		bremfree(bp);
  		info->lazycount += cluster_awrite(bp);
  		waitrunningbufspace();
  		vm_wait_nominal();
  		if (info->lazylimit && info->lazycount >= info->lazylimit)
  			error = 1;
  		else
  			error = 0;
  	}
  	return(-error);
  }
  
  /*
   * Associate a buffer with a vnode.
   *
   * MPSAFE
   */
  int
  bgetvp(struct vnode *vp, struct buf *bp, int testsize)
  {
  	KASSERT(bp->b_vp == NULL, ("bgetvp: not free"));
  	KKASSERT((bp->b_flags & (B_HASHED|B_DELWRI|B_VNCLEAN|B_VNDIRTY)) == 0);
  
  	/*
  	 * Insert onto list for new vnode.
  	 */
  	lwkt_gettoken(&vp->v_token);
  
  	if (buf_rb_hash_RB_INSERT(&vp->v_rbhash_tree, bp)) {
  		lwkt_reltoken(&vp->v_token);
  		return (EEXIST);
  	}
  
  	/*
  	 * Diagnostics (mainly for HAMMER debugging).  Check for
  	 * overlapping buffers.
  	 */
  	if (check_buf_overlap) {
  		struct buf *bx;
  		bx = buf_rb_hash_RB_PREV(bp);
  		if (bx) {
  			if (bx->b_loffset + bx->b_bufsize > bp->b_loffset) {
  				kprintf("bgetvp: overlapl %016jx/%d %016jx "
  					"bx %p bp %p\n",
  					(intmax_t)bx->b_loffset,
  					bx->b_bufsize,
  					(intmax_t)bp->b_loffset,
  					bx, bp);
  				if (check_buf_overlap > 1)
  					panic("bgetvp - overlapping buffer");
  			}
  		}
  		bx = buf_rb_hash_RB_NEXT(bp);
  		if (bx) {
  			if (bp->b_loffset + testsize > bx->b_loffset) {
  				kprintf("bgetvp: overlapr %016jx/%d %016jx "
  					"bp %p bx %p\n",
  					(intmax_t)bp->b_loffset,
  					testsize,
  					(intmax_t)bx->b_loffset,
  					bp, bx);
  				if (check_buf_overlap > 1)
  					panic("bgetvp - overlapping buffer");
  			}
  		}
  	}
  	bp->b_vp = vp;
  	bp->b_flags |= B_HASHED;
  	bp->b_flags |= B_VNCLEAN;
  	if (buf_rb_tree_RB_INSERT(&vp->v_rbclean_tree, bp))
  		panic("reassignbuf: dup lblk/clean vp %p bp %p", vp, bp);
  	/*vhold(vp);*/
  	lwkt_reltoken(&vp->v_token);
  	return(0);
  }
  
  /*
   * Disassociate a buffer from a vnode.
   *
   * MPSAFE
   */
  void
  brelvp(struct buf *bp)
  {
  	struct vnode *vp;
  
  	KASSERT(bp->b_vp != NULL, ("brelvp: NULL"));
  
  	/*
  	 * Delete from old vnode list, if on one.
  	 */
  	vp = bp->b_vp;
  	lwkt_gettoken(&vp->v_token);
  	if (bp->b_flags & (B_VNDIRTY | B_VNCLEAN)) {
  		if (bp->b_flags & B_VNDIRTY)
  			buf_rb_tree_RB_REMOVE(&vp->v_rbdirty_tree, bp);
  		else
  			buf_rb_tree_RB_REMOVE(&vp->v_rbclean_tree, bp);
  		bp->b_flags &= ~(B_VNDIRTY | B_VNCLEAN);
  	}
  	if (bp->b_flags & B_HASHED) {
  		buf_rb_hash_RB_REMOVE(&vp->v_rbhash_tree, bp);
  		bp->b_flags &= ~B_HASHED;
  	}
  	if ((vp->v_flag & VONWORKLST) && RB_EMPTY(&vp->v_rbdirty_tree))
  		vn_syncer_remove(vp);
  	bp->b_vp = NULL;
  
  	lwkt_reltoken(&vp->v_token);
  
  	/*vdrop(vp);*/
  }
  
  /*
   * Reassign the buffer to the proper clean/dirty list based on B_DELWRI.
   * This routine is called when the state of the B_DELWRI bit is changed.
   *
   * Must be called with vp->v_token held.
   * MPSAFE
   */
  void
  reassignbuf(struct buf *bp)
  {
  	struct vnode *vp = bp->b_vp;
  	int delay;
  
  	ASSERT_LWKT_TOKEN_HELD(&vp->v_token);
  	++reassignbufcalls;
  
  	/*
  	 * B_PAGING flagged buffers cannot be reassigned because their vp
  	 * is not fully linked in.
  	 */
  	if (bp->b_flags & B_PAGING)
  		panic("cannot reassign paging buffer");
  
  	if (bp->b_flags & B_DELWRI) {
  		/*
  		 * Move to the dirty list, add the vnode to the worklist
  		 */
  		if (bp->b_flags & B_VNCLEAN) {
  			buf_rb_tree_RB_REMOVE(&vp->v_rbclean_tree, bp);
  			bp->b_flags &= ~B_VNCLEAN;
  		}
  		if ((bp->b_flags & B_VNDIRTY) == 0) {
  			if (buf_rb_tree_RB_INSERT(&vp->v_rbdirty_tree, bp)) {
  				panic("reassignbuf: dup lblk vp %p bp %p",
  				      vp, bp);
  			}
  			bp->b_flags |= B_VNDIRTY;
  		}
  		if ((vp->v_flag & VONWORKLST) == 0) {
  			switch (vp->v_type) {
  			case VDIR:
  				delay = dirdelay;
  				break;
  			case VCHR:
  			case VBLK:
  				if (vp->v_rdev && 
  				    vp->v_rdev->si_mountpoint != NULL) {
  					delay = metadelay;
  					break;
  				}
  				/* fall through */
  			default:
  				delay = filedelay;
  			}
  			vn_syncer_add(vp, delay);
  		}
  	} else {
  		/*
  		 * Move to the clean list, remove the vnode from the worklist
  		 * if no dirty blocks remain.
  		 */
  		if (bp->b_flags & B_VNDIRTY) {
  			buf_rb_tree_RB_REMOVE(&vp->v_rbdirty_tree, bp);
  			bp->b_flags &= ~B_VNDIRTY;
  		}
  		if ((bp->b_flags & B_VNCLEAN) == 0) {
  			if (buf_rb_tree_RB_INSERT(&vp->v_rbclean_tree, bp)) {
  				panic("reassignbuf: dup lblk vp %p bp %p",
  				      vp, bp);
  			}
  			bp->b_flags |= B_VNCLEAN;
  		}
  		if ((vp->v_flag & VONWORKLST) &&
  		    RB_EMPTY(&vp->v_rbdirty_tree)) {
  			vn_syncer_remove(vp);
  		}
  	}
  }
  
  /*
   * Create a vnode for a block device.  Used for mounting the root file
   * system.
   *
   * A vref()'d vnode is returned.
   */
  extern struct vop_ops *devfs_vnode_dev_vops_p;
  int
  bdevvp(cdev_t dev, struct vnode **vpp)
  {
  	struct vnode *vp;
  	struct vnode *nvp;
  	int error;
  
  	if (dev == NULL) {
  		*vpp = NULLVP;
  		return (ENXIO);
  	}
  	error = getspecialvnode(VT_NON, NULL, &devfs_vnode_dev_vops_p,
  				&nvp, 0, 0);
  	if (error) {
  		*vpp = NULLVP;
  		return (error);
  	}
  	vp = nvp;
  	vp->v_type = VCHR;
  #if 0
  	vp->v_rdev = dev;
  #endif
  	v_associate_rdev(vp, dev);
  	vp->v_umajor = dev->si_umajor;
  	vp->v_uminor = dev->si_uminor;
  	vx_unlock(vp);
  	*vpp = vp;
  	return (0);
  }
  
  int
  v_associate_rdev(struct vnode *vp, cdev_t dev)
  {
  	if (dev == NULL)
  		return(ENXIO);
  	if (dev_is_good(dev) == 0)
  		return(ENXIO);
  	KKASSERT(vp->v_rdev == NULL);
  	vp->v_rdev = reference_dev(dev);
  	lwkt_gettoken(&spechash_token);
  	SLIST_INSERT_HEAD(&dev->si_hlist, vp, v_cdevnext);
  	lwkt_reltoken(&spechash_token);
  	return(0);
  }
  
  void
  v_release_rdev(struct vnode *vp)
  {
  	cdev_t dev;
  
  	if ((dev = vp->v_rdev) != NULL) {
  		lwkt_gettoken(&spechash_token);
  		SLIST_REMOVE(&dev->si_hlist, vp, vnode, v_cdevnext);
  		vp->v_rdev = NULL;
  		release_dev(dev);
  		lwkt_reltoken(&spechash_token);
  	}
  }
  
  /*
   * Add a vnode to the alias list hung off the cdev_t.  We only associate
   * the device number with the vnode.  The actual device is not associated
   * until the vnode is opened (usually in spec_open()), and will be 
   * disassociated on last close.
   */
  void
  addaliasu(struct vnode *nvp, int x, int y)
  {
  	if (nvp->v_type != VBLK && nvp->v_type != VCHR)
  		panic("addaliasu on non-special vnode");
  	nvp->v_umajor = x;
  	nvp->v_uminor = y;
  }
  
  /*
   * Simple call that a filesystem can make to try to get rid of a
   * vnode.  It will fail if anyone is referencing the vnode (including
   * the caller).
   *
   * The filesystem can check whether its in-memory inode structure still
   * references the vp on return.
   */
  void
  vclean_unlocked(struct vnode *vp)
  {
  	vx_get(vp);
  	if (sysref_isactive(&vp->v_sysref) == 0)
  		vgone_vxlocked(vp);
  	vx_put(vp);
  }
  
  /*
   * Disassociate a vnode from its underlying filesystem. 
   *
   * The vnode must be VX locked and referenced.  In all normal situations
   * there are no active references.  If vclean_vxlocked() is called while
   * there are active references, the vnode is being ripped out and we have
   * to call VOP_CLOSE() as appropriate before we can reclaim it.
   */
  void
  vclean_vxlocked(struct vnode *vp, int flags)
  {
  	int active;
  	int n;
  	vm_object_t object;
  	struct namecache *ncp;
  
  	/*
  	 * If the vnode has already been reclaimed we have nothing to do.
  	 */
  	if (vp->v_flag & VRECLAIMED)
  		return;
  	vsetflags(vp, VRECLAIMED);
  
  	if (verbose_reclaims) {
  		if ((ncp = TAILQ_FIRST(&vp->v_namecache)) != NULL)
  			kprintf("Debug: reclaim %p %s\n", vp, ncp->nc_name);
  	}
  
  	/*
  	 * Scrap the vfs cache
  	 */
  	while (cache_inval_vp(vp, 0) != 0) {
  		kprintf("Warning: vnode %p clean/cache_resolution "
  			"race detected\n", vp);
  		tsleep(vp, 0, "vclninv", 2);
  	}
  
  	/*
  	 * Check to see if the vnode is in use. If so we have to reference it
  	 * before we clean it out so that its count cannot fall to zero and
  	 * generate a race against ourselves to recycle it.
  	 */
  	active = sysref_isactive(&vp->v_sysref);
  
  	/*
  	 * Clean out any buffers associated with the vnode and destroy its
  	 * object, if it has one. 
  	 */
  	vinvalbuf(vp, V_SAVE, 0, 0);
  
  	/*
  	 * If purging an active vnode (typically during a forced unmount
  	 * or reboot), it must be closed and deactivated before being
  	 * reclaimed.  This isn't really all that safe, but what can
  	 * we do? XXX.
  	 *
  	 * Note that neither of these routines unlocks the vnode.
  	 */
  	if (active && (flags & DOCLOSE)) {
  		while ((n = vp->v_opencount) != 0) {
  			if (vp->v_writecount)
  				VOP_CLOSE(vp, FWRITE|FNONBLOCK);
  			else
  				VOP_CLOSE(vp, FNONBLOCK);
  			if (vp->v_opencount == n) {
  				kprintf("Warning: unable to force-close"
  				       " vnode %p\n", vp);
  				break;
  			}
  		}
  	}
  
  	/*
  	 * If the vnode has not been deactivated, deactivated it.  Deactivation
  	 * can create new buffers and VM pages so we have to call vinvalbuf()
  	 * again to make sure they all get flushed.
  	 *
  	 * This can occur if a file with a link count of 0 needs to be
  	 * truncated.
  	 *
  	 * If the vnode is already dead don't try to deactivate it.
  	 */
  	if ((vp->v_flag & VINACTIVE) == 0) {
  		vsetflags(vp, VINACTIVE);
  		if (vp->v_mount)
  			VOP_INACTIVE(vp);
  		vinvalbuf(vp, V_SAVE, 0, 0);
  	}
  
  	/*
  	 * If the vnode has an object, destroy it.
  	 */
  	while ((object = vp->v_object) != NULL) {
  		vm_object_hold(object);
  		if (object == vp->v_object)
  			break;
  		vm_object_drop(object);
  	}
  
  	if (object != NULL) {
  		if (object->ref_count == 0) {
  			if ((object->flags & OBJ_DEAD) == 0)
  				vm_object_terminate(object);
  			vm_object_drop(object);
  			vclrflags(vp, VOBJBUF);
  		} else {
  			vm_pager_deallocate(object);
  			vclrflags(vp, VOBJBUF);
  			vm_object_drop(object);
  		}
  	}
  	KKASSERT((vp->v_flag & VOBJBUF) == 0);
  
  	/*
  	 * Reclaim the vnode if not already dead.
  	 */
  	if (vp->v_mount && VOP_RECLAIM(vp))
  		panic("vclean: cannot reclaim");
  
  	/*
  	 * Done with purge, notify sleepers of the grim news.
  	 */
  	vp->v_ops = &dead_vnode_vops_p;
  	vn_gone(vp);
  	vp->v_tag = VT_NON;
  
  	/*
  	 * If we are destroying an active vnode, reactivate it now that
  	 * we have reassociated it with deadfs.  This prevents the system
  	 * from crashing on the vnode due to it being unexpectedly marked
  	 * as inactive or reclaimed.
  	 */
  	if (active && (flags & DOCLOSE)) {
  		vclrflags(vp, VINACTIVE | VRECLAIMED);
  	}
  }
  
  /*
   * Eliminate all activity associated with the requested vnode
   * and with all vnodes aliased to the requested vnode.
   *
   * The vnode must be referenced but should not be locked.
   */
  int
  vrevoke(struct vnode *vp, struct ucred *cred)
  {
  	struct vnode *vq;
  	struct vnode *vqn;
  	cdev_t dev;
  	int error;
  
  	/*
  	 * If the vnode has a device association, scrap all vnodes associated
  	 * with the device.  Don't let the device disappear on us while we
  	 * are scrapping the vnodes.
  	 *
  	 * The passed vp will probably show up in the list, do not VX lock
  	 * it twice!
  	 *
  	 * Releasing the vnode's rdev here can mess up specfs's call to
  	 * device close, so don't do it.  The vnode has been disassociated
  	 * and the device will be closed after the last ref on the related
  	 * fp goes away (if not still open by e.g. the kernel).
  	 */
  	if (vp->v_type != VCHR) {
  		error = fdrevoke(vp, DTYPE_VNODE, cred);
  		return (error);
  	}
  	if ((dev = vp->v_rdev) == NULL) {
  		return(0);
  	}
  	reference_dev(dev);
  	lwkt_gettoken(&spechash_token);
  
  restart:
  	vqn = SLIST_FIRST(&dev->si_hlist);
  	if (vqn)
  		vhold(vqn);
  	while ((vq = vqn) != NULL) {
  		if (sysref_isactive(&vq->v_sysref)) {
  			vref(vq);
  			fdrevoke(vq, DTYPE_VNODE, cred);
  			/*v_release_rdev(vq);*/
  			vrele(vq);
  			if (vq->v_rdev != dev) {
  				vdrop(vq);
  				goto restart;
  			}
  		}
  		vqn = SLIST_NEXT(vq, v_cdevnext);
  		if (vqn)
  			vhold(vqn);
  		vdrop(vq);
  	}
  	lwkt_reltoken(&spechash_token);
  	dev_drevoke(dev);
  	release_dev(dev);
  	return (0);
  }
  
  /*
   * This is called when the object underlying a vnode is being destroyed,
   * such as in a remove().  Try to recycle the vnode immediately if the
   * only active reference is our reference.
   *
   * Directory vnodes in the namecache with children cannot be immediately
   * recycled because numerous VOP_N*() ops require them to be stable.
   *
   * To avoid recursive recycling from VOP_INACTIVE implemenetations this
   * function is a NOP if VRECLAIMED is already set.
   */
  int
  vrecycle(struct vnode *vp)
  {
  	if (vp->v_sysref.refcnt <= 1 && (vp->v_flag & VRECLAIMED) == 0) {
  		if (cache_inval_vp_nonblock(vp))
  			return(0);
  		vgone_vxlocked(vp);
  		return (1);
  	}
  	return (0);
  }
  
  /*
   * Return the maximum I/O size allowed for strategy calls on VP.
   *
   * If vp is VCHR or VBLK we dive the device, otherwise we use
   * the vp's mount info.
   *
   * The returned value is clamped at MAXPHYS as most callers cannot use
   * buffers larger than that size.
   */
  int
  vmaxiosize(struct vnode *vp)
  {
  	int maxiosize;
  
  	if (vp->v_type == VBLK || vp->v_type == VCHR)
  		maxiosize = vp->v_rdev->si_iosize_max;
  	else
  		maxiosize = vp->v_mount->mnt_iosize_max;
  
  	if (maxiosize > MAXPHYS)
  		maxiosize = MAXPHYS;
  	return (maxiosize);
  }
  
  /*
   * Eliminate all activity associated with a vnode in preparation for reuse.
   *
   * The vnode must be VX locked and refd and will remain VX locked and refd
   * on return.  This routine may be called with the vnode in any state, as
   * long as it is VX locked.  The vnode will be cleaned out and marked
   * VRECLAIMED but will not actually be reused until all existing refs and
   * holds go away.
   *
   * NOTE: This routine may be called on a vnode which has not yet been
   * already been deactivated (VOP_INACTIVE), or on a vnode which has
   * already been reclaimed.
   *
   * This routine is not responsible for placing us back on the freelist. 
   * Instead, it happens automatically when the caller releases the VX lock
   * (assuming there aren't any other references).
   */
  void
  vgone_vxlocked(struct vnode *vp)
  {
  	/*
  	 * assert that the VX lock is held.  This is an absolute requirement
  	 * now for vgone_vxlocked() to be called.
  	 */
  	KKASSERT(vp->v_lock.lk_exclusivecount == 1);
  
  	/*
  	 * Clean out the filesystem specific data and set the VRECLAIMED
  	 * bit.  Also deactivate the vnode if necessary. 
  	 */
  	vclean_vxlocked(vp, DOCLOSE);
  
  	/*
  	 * Delete from old mount point vnode list, if on one.
  	 */
  	if (vp->v_mount != NULL) {
  		KKASSERT(vp->v_data == NULL);
  		insmntque(vp, NULL);
  	}
  
  	/*
  	 * If special device, remove it from special device alias list
  	 * if it is on one.  This should normally only occur if a vnode is
  	 * being revoked as the device should otherwise have been released
  	 * naturally.
  	 */
  	if ((vp->v_type == VBLK || vp->v_type == VCHR) && vp->v_rdev != NULL) {
  		v_release_rdev(vp);
  	}
  
  	/*
  	 * Set us to VBAD
  	 */
  	vp->v_type = VBAD;
  }
  
  /*
   * Lookup a vnode by device number.
   *
   * Returns non-zero and *vpp set to a vref'd vnode on success.
   * Returns zero on failure.
   */
  int
  vfinddev(cdev_t dev, enum vtype type, struct vnode **vpp)
  {
  	struct vnode *vp;
  
  	lwkt_gettoken(&spechash_token);
  	SLIST_FOREACH(vp, &dev->si_hlist, v_cdevnext) {
  		if (type == vp->v_type) {
  			*vpp = vp;
  			vref(vp);
  			lwkt_reltoken(&spechash_token);
  			return (1);
  		}
  	}
  	lwkt_reltoken(&spechash_token);
  	return (0);
  }
  
  /*
   * Calculate the total number of references to a special device.  This
   * routine may only be called for VBLK and VCHR vnodes since v_rdev is
   * an overloaded field.  Since udev2dev can now return NULL, we have
   * to check for a NULL v_rdev.
   */
  int
  count_dev(cdev_t dev)
  {
  	struct vnode *vp;
  	int count = 0;
  
  	if (SLIST_FIRST(&dev->si_hlist)) {
  		lwkt_gettoken(&spechash_token);
  		SLIST_FOREACH(vp, &dev->si_hlist, v_cdevnext) {
  			count += vp->v_opencount;
  		}
  		lwkt_reltoken(&spechash_token);
  	}
  	return(count);
  }
  
  int
  vcount(struct vnode *vp)
  {
  	if (vp->v_rdev == NULL)
  		return(0);
  	return(count_dev(vp->v_rdev));
  }
  
  /*
   * Initialize VMIO for a vnode.  This routine MUST be called before a
   * VFS can issue buffer cache ops on a vnode.  It is typically called
   * when a vnode is initialized from its inode.
   */
  int
  vinitvmio(struct vnode *vp, off_t filesize, int blksize, int boff)
  {
  	vm_object_t object;
  	int error = 0;
  
  retry:
  	while ((object = vp->v_object) != NULL) {
  		vm_object_hold(object);
  		if (object == vp->v_object)
  			break;
  		vm_object_drop(object);
  	}
  
  	if (object == NULL) {
  		object = vnode_pager_alloc(vp, filesize, 0, 0, blksize, boff);
  
  		/*
  		 * Dereference the reference we just created.  This assumes
  		 * that the object is associated with the vp.
  		 */
  		vm_object_hold(object);
  		object->ref_count--;
  		vrele(vp);
  	} else {
  		if (object->flags & OBJ_DEAD) {
  			vn_unlock(vp);
  			if (vp->v_object == object)
  				vm_object_dead_sleep(object, "vodead");
  			vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
  			vm_object_drop(object);
  			goto retry;
  		}
  	}
  	KASSERT(vp->v_object != NULL, ("vinitvmio: NULL object"));
  	vsetflags(vp, VOBJBUF);
  	vm_object_drop(object);
  
  	return (error);
  }
  
  
  /*
   * Print out a description of a vnode.
   */
  static char *typename[] =
  {"VNON", "VREG", "VDIR", "VBLK", "VCHR", "VLNK", "VSOCK", "VFIFO", "VBAD"};
  
  void
  vprint(char *label, struct vnode *vp)
  {
  	char buf[96];
  
  	if (label != NULL)
  		kprintf("%s: %p: ", label, (void *)vp);
  	else
  		kprintf("%p: ", (void *)vp);
  	kprintf("type %s, sysrefs %d, writecount %d, holdcnt %d,",
  		typename[vp->v_type],
  		vp->v_sysref.refcnt, vp->v_writecount, vp->v_auxrefs);
  	buf[0] = '\0';
  	if (vp->v_flag & VROOT)
  		strcat(buf, "|VROOT");
  	if (vp->v_flag & VPFSROOT)
  		strcat(buf, "|VPFSROOT");
  	if (vp->v_flag & VTEXT)
  		strcat(buf, "|VTEXT");
  	if (vp->v_flag & VSYSTEM)
  		strcat(buf, "|VSYSTEM");
  	if (vp->v_flag & VFREE)
  		strcat(buf, "|VFREE");
  	if (vp->v_flag & VOBJBUF)
  		strcat(buf, "|VOBJBUF");
  	if (buf[0] != '\0')
  		kprintf(" flags (%s)", &buf[1]);
  	if (vp->v_data == NULL) {
  		kprintf("\n");
  	} else {
  		kprintf("\n\t");
  		VOP_PRINT(vp);
  	}
  }
  
  /*
   * Do the usual access checking.
   * file_mode, uid and gid are from the vnode in question,
   * while acc_mode and cred are from the VOP_ACCESS parameter list
   */
  int
  vaccess(enum vtype type, mode_t file_mode, uid_t uid, gid_t gid,
      mode_t acc_mode, struct ucred *cred)
  {
  	mode_t mask;
  	int ismember;
  
  	/*
  	 * Super-user always gets read/write access, but execute access depends
  	 * on at least one execute bit being set.
  	 */
  	if (priv_check_cred(cred, PRIV_ROOT, 0) == 0) {
  		if ((acc_mode & VEXEC) && type != VDIR &&
  		    (file_mode & (S_IXUSR|S_IXGRP|S_IXOTH)) == 0)
  			return (EACCES);
  		return (0);
  	}
  
  	mask = 0;
  
  	/* Otherwise, check the owner. */
  	if (cred->cr_uid == uid) {
  		if (acc_mode & VEXEC)
  			mask |= S_IXUSR;
  		if (acc_mode & VREAD)
  			mask |= S_IRUSR;
  		if (acc_mode & VWRITE)
  			mask |= S_IWUSR;
  		return ((file_mode & mask) == mask ? 0 : EACCES);
  	}
  
  	/* Otherwise, check the groups. */
  	ismember = groupmember(gid, cred);
  	if (cred->cr_svgid == gid || ismember) {
  		if (acc_mode & VEXEC)
  			mask |= S_IXGRP;
  		if (acc_mode & VREAD)
  			mask |= S_IRGRP;
  		if (acc_mode & VWRITE)
  			mask |= S_IWGRP;
  		return ((file_mode & mask) == mask ? 0 : EACCES);
  	}
  
  	/* Otherwise, check everyone else. */
  	if (acc_mode & VEXEC)
  		mask |= S_IXOTH;
  	if (acc_mode & VREAD)
  		mask |= S_IROTH;
  	if (acc_mode & VWRITE)
  		mask |= S_IWOTH;
  	return ((file_mode & mask) == mask ? 0 : EACCES);
  }
  
  #ifdef DDB
  #include <ddb/ddb.h>
  
  static int db_show_locked_vnodes(struct mount *mp, void *data);
  
  /*
   * List all of the locked vnodes in the system.
   * Called when debugging the kernel.
   */
  DB_SHOW_COMMAND(lockedvnodes, lockedvnodes)
  {
  	kprintf("Locked vnodes\n");
  	mountlist_scan(db_show_locked_vnodes, NULL, 
  			MNTSCAN_FORWARD|MNTSCAN_NOBUSY);
  }
  
  static int
  db_show_locked_vnodes(struct mount *mp, void *data __unused)
  {
  	struct vnode *vp;
  
  	TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes) {
  		if (vn_islocked(vp))
  			vprint(NULL, vp);
  	}
  	return(0);
  }
  #endif
  
  /*
   * Top level filesystem related information gathering.
   */
  static int	sysctl_ovfs_conf (SYSCTL_HANDLER_ARGS);
  
  static int
  vfs_sysctl(SYSCTL_HANDLER_ARGS)
  {
  	int *name = (int *)arg1 - 1;	/* XXX */
  	u_int namelen = arg2 + 1;	/* XXX */
  	struct vfsconf *vfsp;
  	int maxtypenum;
  
  #if 1 || defined(COMPAT_PRELITE2)
  	/* Resolve ambiguity between VFS_VFSCONF and VFS_GENERIC. */
  	if (namelen == 1)
  		return (sysctl_ovfs_conf(oidp, arg1, arg2, req));
  #endif
  
  #ifdef notyet
  	/* all sysctl names at this level are at least name and field */
  	if (namelen < 2)
  		return (ENOTDIR);		/* overloaded */
  	if (name[0] != VFS_GENERIC) {
  		vfsp = vfsconf_find_by_typenum(name[0]);
  		if (vfsp == NULL)
  			return (EOPNOTSUPP);
  		return ((*vfsp->vfc_vfsops->vfs_sysctl)(&name[1], namelen - 1,
  		    oldp, oldlenp, newp, newlen, p));
  	}
  #endif
  	switch (name[1]) {
  	case VFS_MAXTYPENUM:
  		if (namelen != 2)
  			return (ENOTDIR);
  		maxtypenum = vfsconf_get_maxtypenum();
  		return (SYSCTL_OUT(req, &maxtypenum, sizeof(maxtypenum)));
  	case VFS_CONF:
  		if (namelen != 3)
  			return (ENOTDIR);	/* overloaded */
  		vfsp = vfsconf_find_by_typenum(name[2]);
  		if (vfsp == NULL)
  			return (EOPNOTSUPP);
  		return (SYSCTL_OUT(req, vfsp, sizeof *vfsp));
  	}
  	return (EOPNOTSUPP);
  }
  
  SYSCTL_NODE(_vfs, VFS_GENERIC, generic, CTLFLAG_RD, vfs_sysctl,
  	"Generic filesystem");
  
  #if 1 || defined(COMPAT_PRELITE2)
  
  static int
  sysctl_ovfs_conf_iter(struct vfsconf *vfsp, void *data)
  {
  	int error;
  	struct ovfsconf ovfs;
  	struct sysctl_req *req = (struct sysctl_req*) data;
  
  	bzero(&ovfs, sizeof(ovfs));
  	ovfs.vfc_vfsops = vfsp->vfc_vfsops;	/* XXX used as flag */
  	strcpy(ovfs.vfc_name, vfsp->vfc_name);
  	ovfs.vfc_index = vfsp->vfc_typenum;
  	ovfs.vfc_refcount = vfsp->vfc_refcount;
  	ovfs.vfc_flags = vfsp->vfc_flags;
  	error = SYSCTL_OUT(req, &ovfs, sizeof ovfs);
  	if (error)
  		return error; /* abort iteration with error code */
  	else
  		return 0; /* continue iterating with next element */
  }
  
  static int
  sysctl_ovfs_conf(SYSCTL_HANDLER_ARGS)
  {
  	return vfsconf_each(sysctl_ovfs_conf_iter, (void*)req);
  }
  
  #endif /* 1 || COMPAT_PRELITE2 */
  
  /*
   * Check to see if a filesystem is mounted on a block device.
   */
  int
  vfs_mountedon(struct vnode *vp)
  {
  	cdev_t dev;
  
  	if ((dev = vp->v_rdev) == NULL) {
  /*		if (vp->v_type != VBLK)
  			dev = get_dev(vp->v_uminor, vp->v_umajor); */
  	}
  	if (dev != NULL && dev->si_mountpoint)
  		return (EBUSY);
  	return (0);
  }
  
  /*
   * Unmount all filesystems. The list is traversed in reverse order
   * of mounting to avoid dependencies.
   */
  
  static int vfs_umountall_callback(struct mount *mp, void *data);
  
  void
  vfs_unmountall(void)
  {
  	int count;
  
  	do {
  		count = mountlist_scan(vfs_umountall_callback, 
  					NULL, MNTSCAN_REVERSE|MNTSCAN_NOBUSY);
  	} while (count);
  }
  
  static
  int
  vfs_umountall_callback(struct mount *mp, void *data)
  {
  	int error;
  
  	error = dounmount(mp, MNT_FORCE);
  	if (error) {
  		mountlist_remove(mp);
  		kprintf("unmount of filesystem mounted from %s failed (", 
  			mp->mnt_stat.f_mntfromname);
  		if (error == EBUSY)
  			kprintf("BUSY)\n");
  		else
  			kprintf("%d)\n", error);
  	}
  	return(1);
  }
  
  /*
   * Checks the mount flags for parameter mp and put the names comma-separated
   * into a string buffer buf with a size limit specified by len.
   *
   * It returns the number of bytes written into buf, and (*errorp) will be
   * set to 0, EINVAL (if passed length is 0), or ENOSPC (supplied buffer was
   * not large enough).  The buffer will be 0-terminated if len was not 0.
   */
  size_t
  vfs_flagstostr(int flags, const struct mountctl_opt *optp,
  	       char *buf, size_t len, int *errorp)
  {
  	static const struct mountctl_opt optnames[] = {
  		{ MNT_ASYNC,            "asynchronous" },
  		{ MNT_EXPORTED,         "NFS exported" },
  		{ MNT_LOCAL,            "local" },
  		{ MNT_NOATIME,          "noatime" },
  		{ MNT_NODEV,            "nodev" },
  		{ MNT_NOEXEC,           "noexec" },
  		{ MNT_NOSUID,           "nosuid" },
  		{ MNT_NOSYMFOLLOW,      "nosymfollow" },
  		{ MNT_QUOTA,            "with-quotas" },
  		{ MNT_RDONLY,           "read-only" },
  		{ MNT_SYNCHRONOUS,      "synchronous" },
  		{ MNT_UNION,            "union" },
  		{ MNT_NOCLUSTERR,       "noclusterr" },
  		{ MNT_NOCLUSTERW,       "noclusterw" },
  		{ MNT_SUIDDIR,          "suiddir" },
  		{ MNT_SOFTDEP,          "soft-updates" },
  		{ MNT_IGNORE,           "ignore" },
  		{ 0,			NULL}
  	};
  	int bwritten;
  	int bleft;
  	int optlen;
  	int actsize;
  
  	*errorp = 0;
  	bwritten = 0;
  	bleft = len - 1;	/* leave room for trailing \0 */
  
  	/*
  	 * Checks the size of the string. If it contains
  	 * any data, then we will append the new flags to
  	 * it.
  	 */
  	actsize = strlen(buf);
  	if (actsize > 0)
  		buf += actsize;
  
  	/* Default flags if no flags passed */
  	if (optp == NULL)
  		optp = optnames;
  
  	if (bleft < 0) {	/* degenerate case, 0-length buffer */
  		*errorp = EINVAL;
  		return(0);
  	}
  
  	for (; flags && optp->o_opt; ++optp) {
  		if ((flags & optp->o_opt) == 0)
  			continue;
  		optlen = strlen(optp->o_name);
  		if (bwritten || actsize > 0) {
  			if (bleft < 2) {
  				*errorp = ENOSPC;
  				break;
  			}
  			buf[bwritten++] = ',';
  			buf[bwritten++] = ' ';
  			bleft -= 2;
  		}
  		if (bleft < optlen) {
  			*errorp = ENOSPC;
  			break;
  		}
  		bcopy(optp->o_name, buf + bwritten, optlen);
  		bwritten += optlen;
  		bleft -= optlen;
  		flags &= ~optp->o_opt;
  	}
  
  	/*
  	 * Space already reserved for trailing \0
  	 */
  	buf[bwritten] = 0;
  	return (bwritten);
  }
  
  /*
   * Build hash lists of net addresses and hang them off the mount point.
   * Called by ufs_mount() to set up the lists of export addresses.
   */
  static int
  vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
  		const struct export_args *argp)
  {
  	struct netcred *np;
  	struct radix_node_head *rnh;
  	int i;
  	struct radix_node *rn;
  	struct sockaddr *saddr, *smask = NULL;
  	struct domain *dom;
  	int error;
  
  	if (argp->ex_addrlen == 0) {
  		if (mp->mnt_flag & MNT_DEFEXPORTED)
  			return (EPERM);
  		np = &nep->ne_defexported;
  		np->netc_exflags = argp->ex_flags;
  		np->netc_anon = argp->ex_anon;
  		np->netc_anon.cr_ref = 1;
  		mp->mnt_flag |= MNT_DEFEXPORTED;
  		return (0);
  	}
  
  	if (argp->ex_addrlen < 0 || argp->ex_addrlen > MLEN)
  		return (EINVAL);
  	if (argp->ex_masklen < 0 || argp->ex_masklen > MLEN)
  		return (EINVAL);
  
  	i = sizeof(struct netcred) + argp->ex_addrlen + argp->ex_masklen;
  	np = (struct netcred *) kmalloc(i, M_NETADDR, M_WAITOK | M_ZERO);
  	saddr = (struct sockaddr *) (np + 1);
  	if ((error = copyin(argp->ex_addr, (caddr_t) saddr, argp->ex_addrlen)))
  		goto out;
  	if (saddr->sa_len > argp->ex_addrlen)
  		saddr->sa_len = argp->ex_addrlen;
  	if (argp->ex_masklen) {
  		smask = (struct sockaddr *)((caddr_t)saddr + argp->ex_addrlen);
  		error = copyin(argp->ex_mask, (caddr_t)smask, argp->ex_masklen);
  		if (error)
  			goto out;
  		if (smask->sa_len > argp->ex_masklen)
  			smask->sa_len = argp->ex_masklen;
  	}
  	i = saddr->sa_family;
  	if ((rnh = nep->ne_rtable[i]) == NULL) {
  		/*
  		 * Seems silly to initialize every AF when most are not used,
  		 * do so on demand here
  		 */
  		SLIST_FOREACH(dom, &domains, dom_next)
  			if (dom->dom_family == i && dom->dom_rtattach) {
  				dom->dom_rtattach((void **) &nep->ne_rtable[i],
  				    dom->dom_rtoffset);
  				break;
  			}
  		if ((rnh = nep->ne_rtable[i]) == NULL) {
  			error = ENOBUFS;
  			goto out;
  		}
  	}
  	rn = (*rnh->rnh_addaddr) ((char *) saddr, (char *) smask, rnh,
  	    np->netc_rnodes);
  	if (rn == NULL || np != (struct netcred *) rn) {	/* already exists */
  		error = EPERM;
  		goto out;
  	}
  	np->netc_exflags = argp->ex_flags;
  	np->netc_anon = argp->ex_anon;
  	np->netc_anon.cr_ref = 1;
  	return (0);
  out:
  	kfree(np, M_NETADDR);
  	return (error);
  }
  
  /* ARGSUSED */
  static int
  vfs_free_netcred(struct radix_node *rn, void *w)
  {
  	struct radix_node_head *rnh = (struct radix_node_head *) w;
  
  	(*rnh->rnh_deladdr) (rn->rn_key, rn->rn_mask, rnh);
  	kfree((caddr_t) rn, M_NETADDR);
  	return (0);
  }
  
  /*
   * Free the net address hash lists that are hanging off the mount points.
   */
  static void
  vfs_free_addrlist(struct netexport *nep)
  {
  	int i;
  	struct radix_node_head *rnh;
  
  	for (i = 0; i <= AF_MAX; i++)
  		if ((rnh = nep->ne_rtable[i])) {
  			(*rnh->rnh_walktree) (rnh, vfs_free_netcred,
  			    (caddr_t) rnh);
  			kfree((caddr_t) rnh, M_RTABLE);
  			nep->ne_rtable[i] = 0;
  		}
  }
  
  int
  vfs_export(struct mount *mp, struct netexport *nep,
  	   const struct export_args *argp)
  {
  	int error;
  
  	if (argp->ex_flags & MNT_DELEXPORT) {
  		if (mp->mnt_flag & MNT_EXPUBLIC) {
  			vfs_setpublicfs(NULL, NULL, NULL);
  			mp->mnt_flag &= ~MNT_EXPUBLIC;
  		}
  		vfs_free_addrlist(nep);
  		mp->mnt_flag &= ~(MNT_EXPORTED | MNT_DEFEXPORTED);
  	}
  	if (argp->ex_flags & MNT_EXPORTED) {
  		if (argp->ex_flags & MNT_EXPUBLIC) {
  			if ((error = vfs_setpublicfs(mp, nep, argp)) != 0)
  				return (error);
  			mp->mnt_flag |= MNT_EXPUBLIC;
  		}
  		if ((error = vfs_hang_addrlist(mp, nep, argp)))
  			return (error);
  		mp->mnt_flag |= MNT_EXPORTED;
  	}
  	return (0);
  }
  
  
  /*
   * Set the publicly exported filesystem (WebNFS). Currently, only
   * one public filesystem is possible in the spec (RFC 2054 and 2055)
   */
  int
  vfs_setpublicfs(struct mount *mp, struct netexport *nep,
  		const struct export_args *argp)
  {
  	int error;
  	struct vnode *rvp;
  	char *cp;
  
  	/*
  	 * mp == NULL -> invalidate the current info, the FS is
  	 * no longer exported. May be called from either vfs_export
  	 * or unmount, so check if it hasn't already been done.
  	 */
  	if (mp == NULL) {
  		if (nfs_pub.np_valid) {
  			nfs_pub.np_valid = 0;
  			if (nfs_pub.np_index != NULL) {
  				kfree(nfs_pub.np_index, M_TEMP);
  				nfs_pub.np_index = NULL;
  			}
  		}
  		return (0);
  	}
  
  	/*
  	 * Only one allowed at a time.
  	 */
  	if (nfs_pub.np_valid != 0 && mp != nfs_pub.np_mount)
  		return (EBUSY);
  
  	/*
  	 * Get real filehandle for root of exported FS.
  	 */
  	bzero((caddr_t)&nfs_pub.np_handle, sizeof(nfs_pub.np_handle));
  	nfs_pub.np_handle.fh_fsid = mp->mnt_stat.f_fsid;
  
  	if ((error = VFS_ROOT(mp, &rvp)))
  		return (error);
  
  	if ((error = VFS_VPTOFH(rvp, &nfs_pub.np_handle.fh_fid)))
  		return (error);
  
  	vput(rvp);
  
  	/*
  	 * If an indexfile was specified, pull it in.
  	 */
  	if (argp->ex_indexfile != NULL) {
  		int namelen;
  
  		error = vn_get_namelen(rvp, &namelen);
  		if (error)
  			return (error);
  		nfs_pub.np_index = kmalloc(namelen, M_TEMP, M_WAITOK);
  		error = copyinstr(argp->ex_indexfile, nfs_pub.np_index,
  		    namelen, NULL);
  		if (!error) {
  			/*
  			 * Check for illegal filenames.
  			 */
  			for (cp = nfs_pub.np_index; *cp; cp++) {
  				if (*cp == '/') {
  					error = EINVAL;
  					break;
  				}
  			}
  		}
  		if (error) {
  			kfree(nfs_pub.np_index, M_TEMP);
  			return (error);
  		}
  	}
  
  	nfs_pub.np_mount = mp;
  	nfs_pub.np_valid = 1;
  	return (0);
  }
  
  struct netcred *
  vfs_export_lookup(struct mount *mp, struct netexport *nep,
  		struct sockaddr *nam)
  {
  	struct netcred *np;
  	struct radix_node_head *rnh;
  	struct sockaddr *saddr;
  
  	np = NULL;
  	if (mp->mnt_flag & MNT_EXPORTED) {
  		/*
  		 * Lookup in the export list first.
  		 */
  		if (nam != NULL) {
  			saddr = nam;
  			rnh = nep->ne_rtable[saddr->sa_family];
  			if (rnh != NULL) {
  				np = (struct netcred *)
  					(*rnh->rnh_matchaddr)((char *)saddr,
  							      rnh);
  				if (np && np->netc_rnodes->rn_flags & RNF_ROOT)
  					np = NULL;
  			}
  		}
  		/*
  		 * If no address match, use the default if it exists.
  		 */
  		if (np == NULL && mp->mnt_flag & MNT_DEFEXPORTED)
  			np = &nep->ne_defexported;
  	}
  	return (np);
  }
  
  /*
   * perform msync on all vnodes under a mount point.  The mount point must
   * be locked.  This code is also responsible for lazy-freeing unreferenced
   * vnodes whos VM objects no longer contain pages.
   *
   * NOTE: MNT_WAIT still skips vnodes in the VXLOCK state.
   *
   * NOTE: XXX VOP_PUTPAGES and friends requires that the vnode be locked,
   * but vnode_pager_putpages() doesn't lock the vnode.  We have to do it
   * way up in this high level function.
   */
  static int vfs_msync_scan1(struct mount *mp, struct vnode *vp, void *data);
  static int vfs_msync_scan2(struct mount *mp, struct vnode *vp, void *data);
  
  void
  vfs_msync(struct mount *mp, int flags) 
  {
  	int vmsc_flags;
  
  	/*
  	 * tmpfs sets this flag to prevent msync(), sync, and the
  	 * filesystem periodic syncer from trying to flush VM pages
  	 * to swap.  Only pure memory pressure flushes tmpfs VM pages
  	 * to swap.
  	 */
  	if (mp->mnt_kern_flag & MNTK_NOMSYNC)
  		return;
  
  	/*
  	 * Ok, scan the vnodes for work.
  	 */
  	vmsc_flags = VMSC_GETVP;
  	if (flags != MNT_WAIT)
  		vmsc_flags |= VMSC_NOWAIT;
  	vmntvnodescan(mp, vmsc_flags,
  		      vfs_msync_scan1, vfs_msync_scan2,
  		      (void *)(intptr_t)flags);
  }
  
  /*
   * scan1 is a fast pre-check.  There could be hundreds of thousands of
   * vnodes, we cannot afford to do anything heavy weight until we have a
   * fairly good indication that there is work to do.
   */
  static
  int
  vfs_msync_scan1(struct mount *mp, struct vnode *vp, void *data)
  {
  	int flags = (int)(intptr_t)data;
  
  	if ((vp->v_flag & VRECLAIMED) == 0) {
  		if (vshouldmsync(vp))
  			return(0);	/* call scan2 */
  		if ((mp->mnt_flag & MNT_RDONLY) == 0 &&
  		    (vp->v_flag & VOBJDIRTY) &&
  		    (flags == MNT_WAIT || vn_islocked(vp) == 0)) {
  			return(0);	/* call scan2 */
  		}
  	}
  
  	/*
  	 * do not call scan2, continue the loop
  	 */
  	return(-1);
  }
  
  /*
   * This callback is handed a locked vnode.
   */
  static
  int
  vfs_msync_scan2(struct mount *mp, struct vnode *vp, void *data)
  {
  	vm_object_t obj;
  	int flags = (int)(intptr_t)data;
  
  	if (vp->v_flag & VRECLAIMED)
  		return(0);
  
  	if ((mp->mnt_flag & MNT_RDONLY) == 0 && (vp->v_flag & VOBJDIRTY)) {
  		if ((obj = vp->v_object) != NULL) {
  			vm_object_page_clean(obj, 0, 0, 
  			 flags == MNT_WAIT ? OBJPC_SYNC : OBJPC_NOSYNC);
  		}
  	}
  	return(0);
  }
  
  /*
   * Wake up anyone interested in vp because it is being revoked.
   */
  void
  vn_gone(struct vnode *vp)
  {
  	lwkt_gettoken(&vp->v_token);
  	KNOTE(&vp->v_pollinfo.vpi_kqinfo.ki_note, NOTE_REVOKE);
  	lwkt_reltoken(&vp->v_token);
  }
  
  /*
   * extract the cdev_t from a VBLK or VCHR.  The vnode must have been opened
   * (or v_rdev might be NULL).
   */
  cdev_t
  vn_todev(struct vnode *vp)
  {
  	if (vp->v_type != VBLK && vp->v_type != VCHR)
  		return (NULL);
  	KKASSERT(vp->v_rdev != NULL);
  	return (vp->v_rdev);
  }
  
  /*
   * Check if vnode represents a disk device.  The vnode does not need to be
   * opened.
   *
   * MPALMOSTSAFE
   */
  int
  vn_isdisk(struct vnode *vp, int *errp)
  {
  	cdev_t dev;
  
  	if (vp->v_type != VCHR) {
  		if (errp != NULL)
  			*errp = ENOTBLK;
  		return (0);
  	}
  
  	dev = vp->v_rdev;
  
  	if (dev == NULL) {
  		if (errp != NULL)
  			*errp = ENXIO;
  		return (0);
  	}
  	if (dev_is_good(dev) == 0) {
  		if (errp != NULL)
  			*errp = ENXIO;
  		return (0);
  	}
  	if ((dev_dflags(dev) & D_DISK) == 0) {
  		if (errp != NULL)
  			*errp = ENOTBLK;
  		return (0);
  	}
  	if (errp != NULL)
  		*errp = 0;
  	return (1);
  }
  
  int
  vn_get_namelen(struct vnode *vp, int *namelen)
  {
  	int error;
  	register_t retval[2];
  
  	error = VOP_PATHCONF(vp, _PC_NAME_MAX, retval);
  	if (error)
  		return (error);
  	*namelen = (int)retval[0];
  	return (0);
  }
  
  int
  vop_write_dirent(int *error, struct uio *uio, ino_t d_ino, uint8_t d_type, 
  		uint16_t d_namlen, const char *d_name)
  {
  	struct dirent *dp;
  	size_t len;
  
  	len = _DIRENT_RECLEN(d_namlen);
  	if (len > uio->uio_resid)
  		return(1);
  
  	dp = kmalloc(len, M_TEMP, M_WAITOK | M_ZERO);
  
  	dp->d_ino = d_ino;
  	dp->d_namlen = d_namlen;
  	dp->d_type = d_type;
  	bcopy(d_name, dp->d_name, d_namlen);
  
  	*error = uiomove((caddr_t)dp, len, uio);
  
  	kfree(dp, M_TEMP);
  
  	return(0);
  }
  
  void
  vn_mark_atime(struct vnode *vp, struct thread *td)
  {
  	struct proc *p = td->td_proc;
  	struct ucred *cred = p ? p->p_ucred : proc0.p_ucred;
  
  	if ((vp->v_mount->mnt_flag & (MNT_NOATIME | MNT_RDONLY)) == 0) {
  		VOP_MARKATIME(vp, cred);
  	}
  }
  