FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_subr.c

     /*      $NetBSD: vfs_subr.c,v 1.218.2.5 2005/12/29 01:37:32 riz Exp $   */
     
     /*-
      * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * This code is derived from software contributed to The NetBSD Foundation
      * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
      * NASA Ames Research Center.
     *
     * 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. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the NetBSD
     *      Foundation, Inc. and its contributors.
     * 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
     */
    
    /*
     * 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  8.13 (Berkeley) 4/18/94
     */
    
    /*
     * External virtual filesystem routines
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: vfs_subr.c,v 1.218.2.5 2005/12/29 01:37:32 riz Exp $");
    
    #include "opt_inet.h"
    #include "opt_ddb.h"
    #include "opt_compat_netbsd.h"
    #include "opt_compat_43.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/proc.h>
    #include <sys/kernel.h>
    #include <sys/mount.h>
    #include <sys/time.h>
    #include <sys/event.h>
    #include <sys/fcntl.h>
    #include <sys/vnode.h>
    #include <sys/stat.h>
    #include <sys/namei.h>
    #include <sys/ucred.h>
   #include <sys/buf.h>
   #include <sys/errno.h>
   #include <sys/malloc.h>
   #include <sys/domain.h>
   #include <sys/mbuf.h>
   #include <sys/sa.h>
   #include <sys/syscallargs.h>
   #include <sys/device.h>
   #include <sys/dirent.h>
   #include <sys/filedesc.h>
   
   #include <miscfs/specfs/specdev.h>
   #include <miscfs/genfs/genfs.h>
   #include <miscfs/syncfs/syncfs.h>
   
   #include <netinet/in.h>
   
   #include <uvm/uvm.h>
   #include <uvm/uvm_ddb.h>
   
   #include <netinet/in.h>
   
   #include <sys/sysctl.h>
   
   const enum vtype iftovt_tab[16] = {
           VNON, VFIFO, VCHR, VNON, VDIR, VNON, VBLK, VNON,
           VREG, VNON, VLNK, VNON, VSOCK, VNON, VNON, VBAD,
   };
   const int       vttoif_tab[9] = {
           0, S_IFREG, S_IFDIR, S_IFBLK, S_IFCHR, S_IFLNK,
           S_IFSOCK, S_IFIFO, S_IFMT,
   };
   
   int doforce = 1;                /* 1 => permit forcible unmounting */
   int prtactive = 0;              /* 1 => print out reclaim of active vnodes */
   
   extern int dovfsusermount;      /* 1 => permit any user to mount filesystems */
   
   /*
    * Insq/Remq for the vnode usage lists.
    */
   #define bufinsvn(bp, dp)        LIST_INSERT_HEAD(dp, bp, b_vnbufs)
   #define bufremvn(bp) {                                                  \
           LIST_REMOVE(bp, b_vnbufs);                                      \
           (bp)->b_vnbufs.le_next = NOLIST;                                \
   }
   /* TAILQ_HEAD(freelst, vnode) vnode_free_list = vnode free list (in vnode.h) */
   struct freelst vnode_free_list = TAILQ_HEAD_INITIALIZER(vnode_free_list);
   struct freelst vnode_hold_list = TAILQ_HEAD_INITIALIZER(vnode_hold_list);
   
   struct mntlist mountlist =                      /* mounted filesystem list */
       CIRCLEQ_HEAD_INITIALIZER(mountlist);
   struct vfs_list_head vfs_list =                 /* vfs list */
       LIST_HEAD_INITIALIZER(vfs_list);
   
   struct nfs_public nfs_pub;                      /* publicly exported FS */
   
   struct simplelock mountlist_slock = SIMPLELOCK_INITIALIZER;
   static struct simplelock mntid_slock = SIMPLELOCK_INITIALIZER;
   struct simplelock mntvnode_slock = SIMPLELOCK_INITIALIZER;
   struct simplelock vnode_free_list_slock = SIMPLELOCK_INITIALIZER;
   struct simplelock spechash_slock = SIMPLELOCK_INITIALIZER;
   
   /* XXX - gross; single global lock to protect v_numoutput */
   struct simplelock global_v_numoutput_slock = SIMPLELOCK_INITIALIZER;
   
   /*
    * These define the root filesystem and device.
    */
   struct mount *rootfs;
   struct vnode *rootvnode;
   struct device *root_device;                     /* root device */
   
   struct pool vnode_pool;                         /* memory pool for vnodes */
   
   MALLOC_DEFINE(M_VNODE, "vnodes", "Dynamically allocated vnodes");
   
   /*
    * Local declarations.
    */
   void insmntque(struct vnode *, struct mount *);
   int getdevvp(dev_t, struct vnode **, enum vtype);
   void vgoneall(struct vnode *);
   
   void vclean(struct vnode *, int, struct proc *);
   
   static int vfs_hang_addrlist(struct mount *, struct netexport *,
                                struct export_args *);
   static int vfs_free_netcred(struct radix_node *, void *);
   static void vfs_free_addrlist(struct netexport *);
   static struct vnode *getcleanvnode(struct proc *);
   
   #ifdef DEBUG
   void printlockedvnodes(void);
   #endif
   
   /*
    * Initialize the vnode management data structures.
    */
   void
   vntblinit()
   {
   
           pool_init(&vnode_pool, sizeof(struct vnode), 0, 0, 0, "vnodepl",
               &pool_allocator_nointr);
   
           /*
            * Initialize the filesystem syncer.
            */
           vn_initialize_syncerd();
   }
   
   int
   vfs_drainvnodes(long target, struct proc *p)
   {
   
           simple_lock(&vnode_free_list_slock);
           while (numvnodes > target) {
                   struct vnode *vp;
   
                   vp = getcleanvnode(p);
                   if (vp == NULL)
                           return EBUSY; /* give up */
                   pool_put(&vnode_pool, vp);
                   simple_lock(&vnode_free_list_slock);
                   numvnodes--;
           }
           simple_unlock(&vnode_free_list_slock);
   
           return 0;
   }
   
   /*
    * grab a vnode from freelist and clean it.
    */
   struct vnode *
   getcleanvnode(p)
           struct proc *p;
   {
           struct vnode *vp;
           struct mount *mp;
           struct freelst *listhd;
   
           LOCK_ASSERT(simple_lock_held(&vnode_free_list_slock));
           if ((vp = TAILQ_FIRST(listhd = &vnode_free_list)) == NULL)
                   vp = TAILQ_FIRST(listhd = &vnode_hold_list);
           for (; vp != NULL; vp = TAILQ_NEXT(vp, v_freelist)) {
                   if (!simple_lock_try(&vp->v_interlock))
                           continue;
                   /*
                    * as our lwp might hold the underlying vnode locked,
                    * don't try to reclaim the VLAYER vnode if it's locked.
                    */
                   if ((vp->v_flag & VXLOCK) == 0 &&
                       ((vp->v_flag & VLAYER) == 0 || VOP_ISLOCKED(vp) == 0)) {
                           if (vn_start_write(vp, &mp, V_NOWAIT) == 0)
                                   break;
                   }
                   mp = NULL;
                   simple_unlock(&vp->v_interlock);
           }
   
           if (vp == NULLVP) {
                   simple_unlock(&vnode_free_list_slock);
                   return NULLVP;
           }
   
           if (vp->v_usecount)
                   panic("free vnode isn't, vp %p", vp);
           TAILQ_REMOVE(listhd, vp, v_freelist);
           /* see comment on why 0xdeadb is set at end of vgone (below) */
           vp->v_freelist.tqe_prev = (struct vnode **)0xdeadb;
           simple_unlock(&vnode_free_list_slock);
           vp->v_lease = NULL;
   
           if (vp->v_type != VBAD)
                   vgonel(vp, p);
           else
                   simple_unlock(&vp->v_interlock);
           vn_finished_write(mp, 0);
   #ifdef DIAGNOSTIC
           if (vp->v_data || vp->v_uobj.uo_npages ||
               TAILQ_FIRST(&vp->v_uobj.memq))
                   panic("cleaned vnode isn't, vp %p", vp);
           if (vp->v_numoutput)
                   panic("clean vnode has pending I/O's, vp %p", vp);
   #endif
           KASSERT((vp->v_flag & VONWORKLST) == 0);
   
           return vp;
   }
   
   /*
    * Mark a mount point as busy. Used to synchronize access and to delay
    * unmounting. Interlock is not released on failure.
    */
   int
   vfs_busy(mp, flags, interlkp)
           struct mount *mp;
           int flags;
           struct simplelock *interlkp;
   {
           int lkflags;
   
           while (mp->mnt_iflag & IMNT_UNMOUNT) {
                   int gone;
   
                   if (flags & LK_NOWAIT)
                           return (ENOENT);
                   if ((flags & LK_RECURSEFAIL) && mp->mnt_unmounter != NULL
                       && mp->mnt_unmounter == curproc)
                           return (EDEADLK);
                   if (interlkp)
                           simple_unlock(interlkp);
                   /*
                    * Since all busy locks are shared except the exclusive
                    * lock granted when unmounting, the only place that a
                    * wakeup needs to be done is at the release of the
                    * exclusive lock at the end of dounmount.
                    *
                    * XXX MP: add spinlock protecting mnt_wcnt here once you
                    * can atomically unlock-and-sleep.
                    */
                   mp->mnt_wcnt++;
                   tsleep((caddr_t)mp, PVFS, "vfs_busy", 0);
                   mp->mnt_wcnt--;
                   gone = mp->mnt_iflag & IMNT_GONE;
   
                   if (mp->mnt_wcnt == 0)
                           wakeup(&mp->mnt_wcnt);
                   if (interlkp)
                           simple_lock(interlkp);
                   if (gone)
                           return (ENOENT);
           }
           lkflags = LK_SHARED;
           if (interlkp)
                   lkflags |= LK_INTERLOCK;
           if (lockmgr(&mp->mnt_lock, lkflags, interlkp))
                   panic("vfs_busy: unexpected lock failure");
           return (0);
   }
   
   /*
    * Free a busy filesystem.
    */
   void
   vfs_unbusy(mp)
           struct mount *mp;
   {
   
           lockmgr(&mp->mnt_lock, LK_RELEASE, NULL);
   }
   
   /*
    * Lookup a filesystem type, and if found allocate and initialize
    * a mount structure for it.
    *
    * Devname is usually updated by mount(8) after booting.
    */
   int
   vfs_rootmountalloc(fstypename, devname, mpp)
           char *fstypename;
           char *devname;
           struct mount **mpp;
   {
           struct vfsops *vfsp = NULL;
           struct mount *mp;
   
           LIST_FOREACH(vfsp, &vfs_list, vfs_list)
                   if (!strncmp(vfsp->vfs_name, fstypename, MFSNAMELEN))
                           break;
   
           if (vfsp == NULL)
                   return (ENODEV);
           mp = malloc((u_long)sizeof(struct mount), M_MOUNT, M_WAITOK);
           memset((char *)mp, 0, (u_long)sizeof(struct mount));
           lockinit(&mp->mnt_lock, PVFS, "vfslock", 0, 0);
           (void)vfs_busy(mp, LK_NOWAIT, 0);
           LIST_INIT(&mp->mnt_vnodelist);
           mp->mnt_op = vfsp;
           mp->mnt_flag = MNT_RDONLY;
           mp->mnt_vnodecovered = NULLVP;
           vfsp->vfs_refcount++;
           strncpy(mp->mnt_stat.f_fstypename, vfsp->vfs_name, MFSNAMELEN);
           mp->mnt_stat.f_mntonname[0] = '/';
           (void) copystr(devname, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 0);
           *mpp = mp;
           return (0);
   }
   
   /*
    * Lookup a mount point by filesystem identifier.
    */
   struct mount *
   vfs_getvfs(fsid)
           fsid_t *fsid;
   {
           struct mount *mp;
   
           simple_lock(&mountlist_slock);
           CIRCLEQ_FOREACH(mp, &mountlist, mnt_list) {
                   if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
                       mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
                           simple_unlock(&mountlist_slock);
                           return (mp);
                   }
           }
           simple_unlock(&mountlist_slock);
           return ((struct mount *)0);
   }
   
   /*
    * Get a new unique fsid
    */
   void
   vfs_getnewfsid(mp)
           struct mount *mp;
   {
           static u_short xxxfs_mntid;
           fsid_t tfsid;
           int mtype;
   
           simple_lock(&mntid_slock);
           mtype = makefstype(mp->mnt_op->vfs_name);
           mp->mnt_stat.f_fsid.val[0] = makedev(mtype, 0);
           mp->mnt_stat.f_fsid.val[1] = mtype;
           if (xxxfs_mntid == 0)
                   ++xxxfs_mntid;
           tfsid.val[0] = makedev(mtype & 0xff, xxxfs_mntid);
           tfsid.val[1] = mtype;
           if (!CIRCLEQ_EMPTY(&mountlist)) {
                   while (vfs_getvfs(&tfsid)) {
                           tfsid.val[0]++;
                           xxxfs_mntid++;
                   }
           }
           mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
           simple_unlock(&mntid_slock);
   }
   
   /*
    * Make a 'unique' number from a mount type name.
    */
   long
   makefstype(type)
           const char *type;
   {
           long rv;
   
           for (rv = 0; *type; type++) {
                   rv <<= 2;
                   rv ^= *type;
           }
           return rv;
   }
   
   
   /*
    * Set vnode attributes to VNOVAL
    */
   void
   vattr_null(vap)
           struct vattr *vap;
   {
   
           vap->va_type = VNON;
   
           /*
            * Assign individually so that it is safe even if size and
            * sign of each member are varied.
            */
           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_size = VNOVAL;
           vap->va_blocksize = VNOVAL;
           vap->va_atime.tv_sec =
               vap->va_mtime.tv_sec =
               vap->va_ctime.tv_sec =
               vap->va_birthtime.tv_sec = VNOVAL;
           vap->va_atime.tv_nsec =
               vap->va_mtime.tv_nsec =
               vap->va_ctime.tv_nsec =
               vap->va_birthtime.tv_nsec = VNOVAL;
           vap->va_gen = VNOVAL;
           vap->va_flags = VNOVAL;
           vap->va_rdev = VNOVAL;
           vap->va_bytes = VNOVAL;
           vap->va_vaflags = 0;
   }
   
   /*
    * Routines having to do with the management of the vnode table.
    */
   extern int (**dead_vnodeop_p)(void *);
   long numvnodes;
   
   /*
    * Return the next vnode from the free list.
    */
   int
   getnewvnode(tag, mp, vops, vpp)
           enum vtagtype tag;
           struct mount *mp;
           int (**vops)(void *);
           struct vnode **vpp;
   {
           extern struct uvm_pagerops uvm_vnodeops;
           struct uvm_object *uobj;
           struct proc *p = curproc;       /* XXX */
           static int toggle;
           struct vnode *vp;
           int error = 0, tryalloc;
   
    try_again:
           if (mp) {
                   /*
                    * Mark filesystem busy while we're creating a vnode.
                    * If unmount is in progress, this will wait; if the
                    * unmount succeeds (only if umount -f), this will
                    * return an error.  If the unmount fails, we'll keep
                    * going afterwards.
                    * (This puts the per-mount vnode list logically under
                    * the protection of the vfs_busy lock).
                    */
                   error = vfs_busy(mp, LK_RECURSEFAIL, 0);
                   if (error && error != EDEADLK)
                           return error;
           }
   
           /*
            * We must choose whether to allocate a new vnode or recycle an
            * existing one. The criterion for allocating a new one is that
            * the total number of vnodes is less than the number desired or
            * there are no vnodes on either free list. Generally we only
            * want to recycle vnodes that have no buffers associated with
            * them, so we look first on the vnode_free_list. If it is empty,
            * we next consider vnodes with referencing buffers on the
            * vnode_hold_list. The toggle ensures that half the time we
            * will use a buffer from the vnode_hold_list, and half the time
            * we will allocate a new one unless the list has grown to twice
            * the desired size. We are reticent to recycle vnodes from the
            * vnode_hold_list because we will lose the identity of all its
            * referencing buffers.
            */
   
           vp = NULL;
   
           simple_lock(&vnode_free_list_slock);
   
           toggle ^= 1;
           if (numvnodes > 2 * desiredvnodes)
                   toggle = 0;
   
           tryalloc = numvnodes < desiredvnodes ||
               (TAILQ_FIRST(&vnode_free_list) == NULL &&
                (TAILQ_FIRST(&vnode_hold_list) == NULL || toggle));
   
           if (tryalloc &&
               (vp = pool_get(&vnode_pool, PR_NOWAIT)) != NULL) {
                   numvnodes++;
                   simple_unlock(&vnode_free_list_slock);
                   memset(vp, 0, sizeof(*vp));
                   simple_lock_init(&vp->v_interlock);
                   uobj = &vp->v_uobj;
                   uobj->pgops = &uvm_vnodeops;
                   uobj->uo_npages = 0;
                   TAILQ_INIT(&uobj->memq);
           } else {
                   vp = getcleanvnode(p);
                   /*
                    * Unless this is a bad time of the month, at most
                    * the first NCPUS items on the free list are
                    * locked, so this is close enough to being empty.
                    */
                   if (vp == NULLVP) {
                           if (mp && error != EDEADLK)
                                   vfs_unbusy(mp);
                           if (tryalloc) {
                                   printf("WARNING: unable to allocate new "
                                       "vnode, retrying...\n");
                                   (void) tsleep(&lbolt, PRIBIO, "newvn", hz);
                                   goto try_again;
                           }
                           tablefull("vnode", "increase kern.maxvnodes or NVNODE");
                           *vpp = 0;
                           return (ENFILE);
                   }
                   vp->v_flag = 0;
                   vp->v_socket = NULL;
   #ifdef VERIFIED_EXEC
                   vp->fp_status = FINGERPRINT_INVALID;
   #endif
           }
           vp->v_type = VNON;
           vp->v_vnlock = &vp->v_lock;
           lockinit(vp->v_vnlock, PVFS, "vnlock", 0, 0);
           cache_purge(vp);
           vp->v_tag = tag;
           vp->v_op = vops;
           insmntque(vp, mp);
           *vpp = vp;
           vp->v_usecount = 1;
           vp->v_data = 0;
           simple_lock_init(&vp->v_uobj.vmobjlock);
   
           /*
            * initialize uvm_object within vnode.
            */
   
           uobj = &vp->v_uobj;
           KASSERT(uobj->pgops == &uvm_vnodeops);
           KASSERT(uobj->uo_npages == 0);
           KASSERT(TAILQ_FIRST(&uobj->memq) == NULL);
           vp->v_size = VSIZENOTSET;
   
           if (mp && error != EDEADLK)
                   vfs_unbusy(mp);
           return (0);
   }
   
   /*
    * This is really just the reverse of getnewvnode(). Needed for
    * VFS_VGET functions who may need to push back a vnode in case
    * of a locking race.
    */
   void
   ungetnewvnode(vp)
           struct vnode *vp;
   {
   #ifdef DIAGNOSTIC
           if (vp->v_usecount != 1)
                   panic("ungetnewvnode: busy vnode");
   #endif
           vp->v_usecount--;
           insmntque(vp, NULL);
           vp->v_type = VBAD;
   
           simple_lock(&vp->v_interlock);
           /*
            * Insert at head of LRU list
            */
           simple_lock(&vnode_free_list_slock);
           if (vp->v_holdcnt > 0)
                   TAILQ_INSERT_HEAD(&vnode_hold_list, vp, v_freelist);
           else
                   TAILQ_INSERT_HEAD(&vnode_free_list, vp, v_freelist);
           simple_unlock(&vnode_free_list_slock);
           simple_unlock(&vp->v_interlock);
   }
   
   /*
    * Move a vnode from one mount queue to another.
    */
   void
   insmntque(vp, mp)
           struct vnode *vp;
           struct mount *mp;
   {
   
   #ifdef DIAGNOSTIC
           if ((mp != NULL) &&
               (mp->mnt_iflag & IMNT_UNMOUNT) &&
               !(mp->mnt_flag & MNT_SOFTDEP) &&
               vp->v_tag != VT_VFS) {
                   panic("insmntque into dying filesystem");
           }
   #endif
   
           simple_lock(&mntvnode_slock);
           /*
            * Delete from old mount point vnode list, if on one.
            */
           if (vp->v_mount != NULL)
                   LIST_REMOVE(vp, v_mntvnodes);
           /*
            * Insert into list of vnodes for the new mount point, if available.
            */
           if ((vp->v_mount = mp) != NULL)
                   LIST_INSERT_HEAD(&mp->mnt_vnodelist, vp, v_mntvnodes);
           simple_unlock(&mntvnode_slock);
   }
   
   /*
    * Update outstanding I/O count and do wakeup if requested.
    */
   void
   vwakeup(bp)
           struct buf *bp;
   {
           struct vnode *vp;
   
           if ((vp = bp->b_vp) != NULL) {
                   /* XXX global lock hack
                    * can't use v_interlock here since this is called
                    * in interrupt context from biodone().
                    */
                   simple_lock(&global_v_numoutput_slock);
                   if (--vp->v_numoutput < 0)
                           panic("vwakeup: neg numoutput, vp %p", vp);
                   if ((vp->v_flag & VBWAIT) && vp->v_numoutput <= 0) {
                           vp->v_flag &= ~VBWAIT;
                           wakeup((caddr_t)&vp->v_numoutput);
                   }
                   simple_unlock(&global_v_numoutput_slock);
           }
   }
   
   /*
    * Flush out and invalidate all buffers associated with a vnode.
    * Called with the underlying vnode locked, which should prevent new dirty
    * buffers from being queued.
    */
   int
   vinvalbuf(vp, flags, cred, p, slpflag, slptimeo)
           struct vnode *vp;
           int flags;
           struct ucred *cred;
           struct proc *p;
           int slpflag, slptimeo;
   {
           struct buf *bp, *nbp;
           int s, error;
           int flushflags = PGO_ALLPAGES | PGO_FREE | PGO_SYNCIO |
                   (flags & V_SAVE ? PGO_CLEANIT : 0);
   
           /* XXXUBC this doesn't look at flags or slp* */
           simple_lock(&vp->v_interlock);
           error = VOP_PUTPAGES(vp, 0, 0, flushflags);
           if (error) {
                   return error;
           }
   
           if (flags & V_SAVE) {
                   error = VOP_FSYNC(vp, cred, FSYNC_WAIT|FSYNC_RECLAIM, 0, 0, p);
                   if (error)
                           return (error);
   #ifdef DIAGNOSTIC
                   s = splbio();
                   if (vp->v_numoutput > 0 || !LIST_EMPTY(&vp->v_dirtyblkhd))
                           panic("vinvalbuf: dirty bufs, vp %p", vp);
                   splx(s);
   #endif
           }
   
           s = splbio();
   
   restart:
           for (bp = LIST_FIRST(&vp->v_cleanblkhd); bp; bp = nbp) {
                   nbp = LIST_NEXT(bp, b_vnbufs);
                   simple_lock(&bp->b_interlock);
                   if (bp->b_flags & B_BUSY) {
                           bp->b_flags |= B_WANTED;
                           error = ltsleep((caddr_t)bp,
                                       slpflag | (PRIBIO + 1) | PNORELOCK,
                                       "vinvalbuf", slptimeo, &bp->b_interlock);
                           if (error) {
                                   splx(s);
                                   return (error);
                           }
                           goto restart;
                   }
                   bp->b_flags |= B_BUSY | B_INVAL | B_VFLUSH;
                   simple_unlock(&bp->b_interlock);
                   brelse(bp);
           }
   
           for (bp = LIST_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
                   nbp = LIST_NEXT(bp, b_vnbufs);
                   simple_lock(&bp->b_interlock);
                   if (bp->b_flags & B_BUSY) {
                           bp->b_flags |= B_WANTED;
                           error = ltsleep((caddr_t)bp,
                                       slpflag | (PRIBIO + 1) | PNORELOCK,
                                       "vinvalbuf", slptimeo, &bp->b_interlock);
                           if (error) {
                                   splx(s);
                                   return (error);
                           }
                           goto restart;
                   }
                   /*
                    * XXX Since there are no node locks for NFS, I believe
                    * there is a slight chance that a delayed write will
                    * occur while sleeping just above, so check for it.
                    */
                   if ((bp->b_flags & B_DELWRI) && (flags & V_SAVE)) {
   #ifdef DEBUG
                           printf("buffer still DELWRI\n");
   #endif
                           bp->b_flags |= B_BUSY | B_VFLUSH;
                           simple_unlock(&bp->b_interlock);
                           VOP_BWRITE(bp);
                           goto restart;
                   }
                   bp->b_flags |= B_BUSY | B_INVAL | B_VFLUSH;
                   simple_unlock(&bp->b_interlock);
                   brelse(bp);
           }
   
   #ifdef DIAGNOSTIC
           if (!LIST_EMPTY(&vp->v_cleanblkhd) || !LIST_EMPTY(&vp->v_dirtyblkhd))
                   panic("vinvalbuf: flush failed, vp %p", vp);
   #endif
   
           splx(s);
   
           return (0);
   }
   
   /*
    * Destroy any in core blocks past the truncation length.
    * Called with the underlying vnode locked, which should prevent new dirty
    * buffers from being queued.
    */
   int
   vtruncbuf(vp, lbn, slpflag, slptimeo)
           struct vnode *vp;
           daddr_t lbn;
           int slpflag, slptimeo;
   {
           struct buf *bp, *nbp;
           int s, error;
           voff_t off;
   
           off = round_page((voff_t)lbn << vp->v_mount->mnt_fs_bshift);
           simple_lock(&vp->v_interlock);
           error = VOP_PUTPAGES(vp, off, 0, PGO_FREE | PGO_SYNCIO);
           if (error) {
                   return error;
           }
   
           s = splbio();
   
   restart:
           for (bp = LIST_FIRST(&vp->v_cleanblkhd); bp; bp = nbp) {
                   nbp = LIST_NEXT(bp, b_vnbufs);
                   if (bp->b_lblkno < lbn)
                           continue;
                   simple_lock(&bp->b_interlock);
                   if (bp->b_flags & B_BUSY) {
                           bp->b_flags |= B_WANTED;
                           error = ltsleep(bp, slpflag | (PRIBIO + 1) | PNORELOCK,
                               "vtruncbuf", slptimeo, &bp->b_interlock);
                           if (error) {
                                   splx(s);
                                   return (error);
                           }
                           goto restart;
                   }
                   bp->b_flags |= B_BUSY | B_INVAL | B_VFLUSH;
                   simple_unlock(&bp->b_interlock);
                   brelse(bp);
           }
   
           for (bp = LIST_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
                   nbp = LIST_NEXT(bp, b_vnbufs);
                   if (bp->b_lblkno < lbn)
                           continue;
                   simple_lock(&bp->b_interlock);
                   if (bp->b_flags & B_BUSY) {
                           bp->b_flags |= B_WANTED;
                           error = ltsleep(bp, slpflag | (PRIBIO + 1) | PNORELOCK,
                               "vtruncbuf", slptimeo, &bp->b_interlock);
                           if (error) {
                                   splx(s);
                                   return (error);
                           }
                           goto restart;
                   }
                   bp->b_flags |= B_BUSY | B_INVAL | B_VFLUSH;
                   simple_unlock(&bp->b_interlock);
                   brelse(bp);
           }
   
           splx(s);
   
           return (0);
   }
   
   void
   vflushbuf(vp, sync)
           struct vnode *vp;
           int sync;
   {
           struct buf *bp, *nbp;
           int flags = PGO_CLEANIT | PGO_ALLPAGES | (sync ? PGO_SYNCIO : 0);
           int s;
   
           simple_lock(&vp->v_interlock);
           (void) VOP_PUTPAGES(vp, 0, 0, flags);
   
   loop:
           s = splbio();
           for (bp = LIST_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
                   nbp = LIST_NEXT(bp, b_vnbufs);
                   simple_lock(&bp->b_interlock);
                   if ((bp->b_flags & B_BUSY)) {
                           simple_unlock(&bp->b_interlock);
                           continue;
                   }
                   if ((bp->b_flags & B_DELWRI) == 0)
                           panic("vflushbuf: not dirty, bp %p", bp);
                   bp->b_flags |= B_BUSY | B_VFLUSH;
                   simple_unlock(&bp->b_interlock);
                   splx(s);
                   /*
                    * Wait for I/O associated with indirect blocks to complete,
                    * since there is no way to quickly wait for them below.
                    */
                   if (bp->b_vp == vp || sync == 0)
                           (void) bawrite(bp);
                   else
                           (void) bwrite(bp);
                   goto loop;
           }
           if (sync == 0) {
                   splx(s);
                   return;
           }
           simple_lock(&global_v_numoutput_slock);
           while (vp->v_numoutput) {
                   vp->v_flag |= VBWAIT;
                   ltsleep((caddr_t)&vp->v_numoutput, PRIBIO + 1, "vflushbuf", 0,
                           &global_v_numoutput_slock);
           }
           simple_unlock(&global_v_numoutput_slock);
           splx(s);
           if (!LIST_EMPTY(&vp->v_dirtyblkhd)) {
                   vprint("vflushbuf: dirty", vp);
                   goto loop;
           }
   }
   
   /*
    * Associate a buffer with a vnode.
    */
   void
   bgetvp(vp, bp)
           struct vnode *vp;
           struct buf *bp;
   {
           int s;
   
           if (bp->b_vp)
                   panic("bgetvp: not free, bp %p", bp);
           VHOLD(vp);
           s = splbio();
           bp->b_vp = vp;
           if (vp->v_type == VBLK || vp->v_type == VCHR)
                   bp->b_dev = vp->v_rdev;
           else
                   bp->b_dev = NODEV;
           /*
            * Insert onto list for new vnode.
            */
           bufinsvn(bp, &vp->v_cleanblkhd);
           splx(s);
   }
   
   /*
    * Disassociate a buffer from a vnode.
    */
   void
   brelvp(bp)
           struct buf *bp;
   {
           struct vnode *vp;
           int s;
   
           if (bp->b_vp == NULL)
                   panic("brelvp: vp NULL, bp %p", bp);
   
           s = splbio();
           vp = bp->b_vp;
           /*
            * Delete from old vnode list, if on one.
            */
           if (LIST_NEXT(bp, b_vnbufs) != NOLIST)
                   bufremvn(bp);
   
           if (TAILQ_EMPTY(&vp->v_uobj.memq) && (vp->v_flag & VONWORKLST) &&
               LIST_FIRST(&vp->v_dirtyblkhd) == NULL) {
                   vp->v_flag &= ~VONWORKLST;
                   LIST_REMOVE(vp, v_synclist);
           }
   
           bp->b_vp = NULL;
           HOLDRELE(vp);
           splx(s);
   }
   
   /*
    * Reassign a buffer from one vnode to another.
    * Used to assign file specific control information
    * (indirect blocks) to the vnode to which they belong.
   *
   * This function must be called at splbio().
   */
  void
  reassignbuf(bp, newvp)
          struct buf *bp;
          struct vnode *newvp;
  {
          struct buflists *listheadp;
          int delay;
  
          /*
           * Delete from old vnode list, if on one.
           */
          if (LIST_NEXT(bp, b_vnbufs) != NOLIST)
                  bufremvn(bp);
          /*
           * If dirty, put on list of dirty buffers;
           * otherwise insert onto list of clean buffers.
           */
          if ((bp->b_flags & B_DELWRI) == 0) {
                  listheadp = &newvp->v_cleanblkhd;
                  if (TAILQ_EMPTY(&newvp->v_uobj.memq) &&
                      (newvp->v_flag & VONWORKLST) &&
                      LIST_FIRST(&newvp->v_dirtyblkhd) == NULL) {
                          newvp->v_flag &= ~VONWORKLST;
                          LIST_REMOVE(newvp, v_synclist);
                  }
          } else {
                  listheadp = &newvp->v_dirtyblkhd;
                  if ((newvp->v_flag & VONWORKLST) == 0) {
                          switch (newvp->v_type) {
                          case VDIR:
                                  delay = dirdelay;
                                  break;
                          case VBLK:
                                  if (newvp->v_specmountpoint != NULL) {
                                          delay = metadelay;
                                          break;
                                  }
                                  /* fall through */
                          default:
                                  delay = filedelay;
                                  break;
                          }
                          if (!newvp->v_mount ||
                              (newvp->v_mount->mnt_flag & MNT_ASYNC) == 0)
                                  vn_syncer_add_to_worklist(newvp, delay);
                  }
          }
          bufinsvn(bp, listheadp);
  }
  
  /*
   * Create a vnode for a block device.
   * Used for root filesystem and swap areas.
   * Also used for memory file system special devices.
   */
  int
  bdevvp(dev, vpp)
          dev_t dev;
          struct vnode **vpp;
  {
  
          return (getdevvp(dev, vpp, VBLK));
  }
  
  /*
   * Create a vnode for a character device.
   * Used for kernfs and some console handling.
   */
  int
  cdevvp(dev, vpp)
          dev_t dev;
          struct vnode **vpp;
  {
  
          return (getdevvp(dev, vpp, VCHR));
  }
  
  /*
   * Create a vnode for a device.
   * Used by bdevvp (block device) for root file system etc.,
   * and by cdevvp (character device) for console and kernfs.
   */
  int
  getdevvp(dev, vpp, type)
          dev_t dev;
          struct vnode **vpp;
          enum vtype type;
  {
          struct vnode *vp;
          struct vnode *nvp;
          int error;
  
          if (dev == NODEV) {
                  *vpp = NULLVP;
                  return (0);
          }
          error = getnewvnode(VT_NON, NULL, spec_vnodeop_p, &nvp);
          if (error) {
                  *vpp = NULLVP;
                  return (error);
          }
          vp = nvp;
          vp->v_type = type;
          if ((nvp = checkalias(vp, dev, NULL)) != 0) {
                  vput(vp);
                  vp = nvp;
          }
          *vpp = vp;
          return (0);
  }
  
  /*
   * Check to see if the new vnode represents a special device
   * for which we already have a vnode (either because of
   * bdevvp() or because of a different vnode representing
   * the same block device). If such an alias exists, deallocate
   * the existing contents and return the aliased vnode. The
   * caller is responsible for filling it with its new contents.
   */
  struct vnode *
  checkalias(nvp, nvp_rdev, mp)
          struct vnode *nvp;
          dev_t nvp_rdev;
          struct mount *mp;
  {
          struct proc *p = curproc;       /* XXX */
          struct vnode *vp;
          struct vnode **vpp;
  
          if (nvp->v_type != VBLK && nvp->v_type != VCHR)
                  return (NULLVP);
  
          vpp = &speclisth[SPECHASH(nvp_rdev)];
  loop:
          simple_lock(&spechash_slock);
          for (vp = *vpp; vp; vp = vp->v_specnext) {
                  if (nvp_rdev != vp->v_rdev || nvp->v_type != vp->v_type)
                          continue;
                  /*
                   * Alias, but not in use, so flush it out.
                   */
                  simple_lock(&vp->v_interlock);
                  simple_unlock(&spechash_slock);
                  if (vp->v_usecount == 0) {
                          vgonel(vp, p);
                          goto loop;
                  }
                  /*
                   * What we're interested to know here is if someone else has
                   * removed this vnode from the device hash list while we were
                   * waiting.  This can only happen if vclean() did it, and
                   * this requires the vnode to be locked.  Therefore, we use
                   * LK_SLEEPFAIL and retry.
                   */
                  if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK | LK_SLEEPFAIL))
                          goto loop;
                  simple_lock(&spechash_slock);
                  break;
          }
          if (vp == NULL || vp->v_tag != VT_NON || vp->v_type != VBLK) {
                  MALLOC(nvp->v_specinfo, struct specinfo *,
                          sizeof(struct specinfo), M_VNODE, M_NOWAIT);
                  /* XXX Erg. */
                  if (nvp->v_specinfo == NULL) {
                          simple_unlock(&spechash_slock);
                          uvm_wait("checkalias");
                          goto loop;
                  }
  
                  nvp->v_rdev = nvp_rdev;
                  nvp->v_hashchain = vpp;
                  nvp->v_specnext = *vpp;
                  nvp->v_specmountpoint = NULL;
                  simple_unlock(&spechash_slock);
                  nvp->v_speclockf = NULL;
                  simple_lock_init(&nvp->v_spec_cow_slock);
                  SLIST_INIT(&nvp->v_spec_cow_head);
                  nvp->v_spec_cow_req = 0;
                  nvp->v_spec_cow_count = 0;
  
                  *vpp = nvp;
                  if (vp != NULLVP) {
                          nvp->v_flag |= VALIASED;
                          vp->v_flag |= VALIASED;
                          vput(vp);
                  }
                  return (NULLVP);
          }
          simple_unlock(&spechash_slock);
          VOP_UNLOCK(vp, 0);
          simple_lock(&vp->v_interlock);
          vclean(vp, 0, p);
          vp->v_op = nvp->v_op;
          vp->v_tag = nvp->v_tag;
          vp->v_vnlock = &vp->v_lock;
          lockinit(vp->v_vnlock, PVFS, "vnlock", 0, 0);
          nvp->v_type = VNON;
          insmntque(vp, mp);
          return (vp);
  }
  
  /*
   * Grab a particular vnode from the free list, increment its
   * reference count and lock it. If the vnode lock bit is set the
   * vnode is being eliminated in vgone. In that case, we can not
   * grab the vnode, so the process is awakened when the transition is
   * completed, and an error returned to indicate that the vnode is no
   * longer usable (possibly having been changed to a new file system type).
   */
  int
  vget(vp, flags)
          struct vnode *vp;
          int flags;
  {
          int error;
  
          /*
           * If the vnode is in the process of being cleaned out for
           * another use, we wait for the cleaning to finish and then
           * return failure. Cleaning is determined by checking that
           * the VXLOCK flag is set.
           */
  
          if ((flags & LK_INTERLOCK) == 0)
                  simple_lock(&vp->v_interlock);
          if (vp->v_flag & VXLOCK) {
                  if (flags & LK_NOWAIT) {
                          simple_unlock(&vp->v_interlock);
                          return EBUSY;
                  }
                  vp->v_flag |= VXWANT;
                  ltsleep(vp, PINOD|PNORELOCK, "vget", 0, &vp->v_interlock);
                  return (ENOENT);
          }
          if (vp->v_usecount == 0) {
                  simple_lock(&vnode_free_list_slock);
                  if (vp->v_holdcnt > 0)
                          TAILQ_REMOVE(&vnode_hold_list, vp, v_freelist);
                  else
                          TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
                  simple_unlock(&vnode_free_list_slock);
          }
          vp->v_usecount++;
  #ifdef DIAGNOSTIC
          if (vp->v_usecount == 0) {
                  vprint("vget", vp);
                  panic("vget: usecount overflow, vp %p", vp);
          }
  #endif
          if (flags & LK_TYPE_MASK) {
                  if ((error = vn_lock(vp, flags | LK_INTERLOCK))) {
                          /*
                           * must expand vrele here because we do not want
                           * to call VOP_INACTIVE if the reference count
                           * drops back to zero since it was never really
                           * active. We must remove it from the free list
                           * before sleeping so that multiple processes do
                           * not try to recycle it.
                           */
                          simple_lock(&vp->v_interlock);
                          vp->v_usecount--;
                          if (vp->v_usecount > 0) {
                                  simple_unlock(&vp->v_interlock);
                                  return (error);
                          }
                          /*
                           * insert at tail of LRU list
                           */
                          simple_lock(&vnode_free_list_slock);
                          if (vp->v_holdcnt > 0)
                                  TAILQ_INSERT_TAIL(&vnode_hold_list, vp,
                                      v_freelist);
                          else
                                  TAILQ_INSERT_TAIL(&vnode_free_list, vp,
                                      v_freelist);
                          simple_unlock(&vnode_free_list_slock);
                          simple_unlock(&vp->v_interlock);
                  }
                  return (error);
          }
          simple_unlock(&vp->v_interlock);
          return (0);
  }
  
  /*
   * vput(), just unlock and vrele()
   */
  void
  vput(vp)
          struct vnode *vp;
  {
          struct proc *p = curproc;       /* XXX */
  
  #ifdef DIAGNOSTIC
          if (vp == NULL)
                  panic("vput: null vp");
  #endif
          simple_lock(&vp->v_interlock);
          vp->v_usecount--;
          if (vp->v_usecount > 0) {
                  simple_unlock(&vp->v_interlock);
                  VOP_UNLOCK(vp, 0);
                  return;
          }
  #ifdef DIAGNOSTIC
          if (vp->v_usecount < 0 || vp->v_writecount != 0) {
                  vprint("vput: bad ref count", vp);
                  panic("vput: ref cnt");
          }
  #endif
          /*
           * Insert at tail of LRU list.
           */
          simple_lock(&vnode_free_list_slock);
          if (vp->v_holdcnt > 0)
                  TAILQ_INSERT_TAIL(&vnode_hold_list, vp, v_freelist);
          else
                  TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
          simple_unlock(&vnode_free_list_slock);
          if (vp->v_flag & VEXECMAP) {
                  uvmexp.execpages -= vp->v_uobj.uo_npages;
                  uvmexp.filepages += vp->v_uobj.uo_npages;
          }
          vp->v_flag &= ~(VTEXT|VEXECMAP);
          simple_unlock(&vp->v_interlock);
          VOP_INACTIVE(vp, p);
  }
  
  /*
   * Vnode release.
   * If count drops to zero, call inactive routine and return to freelist.
   */
  void
  vrele(vp)
          struct vnode *vp;
  {
          struct proc *p = curproc;       /* XXX */
  
  #ifdef DIAGNOSTIC
          if (vp == NULL)
                  panic("vrele: null vp");
  #endif
          simple_lock(&vp->v_interlock);
          vp->v_usecount--;
          if (vp->v_usecount > 0) {
                  simple_unlock(&vp->v_interlock);
                  return;
          }
  #ifdef DIAGNOSTIC
          if (vp->v_usecount < 0 || vp->v_writecount != 0) {
                  vprint("vrele: bad ref count", vp);
                  panic("vrele: ref cnt vp %p", vp);
          }
  #endif
          /*
           * Insert at tail of LRU list.
           */
          simple_lock(&vnode_free_list_slock);
          if (vp->v_holdcnt > 0)
                  TAILQ_INSERT_TAIL(&vnode_hold_list, vp, v_freelist);
          else
                  TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
          simple_unlock(&vnode_free_list_slock);
          if (vp->v_flag & VEXECMAP) {
                  uvmexp.execpages -= vp->v_uobj.uo_npages;
                  uvmexp.filepages += vp->v_uobj.uo_npages;
          }
          vp->v_flag &= ~(VTEXT|VEXECMAP);
          if (vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK) == 0)
                  VOP_INACTIVE(vp, p);
  }
  
  #ifdef DIAGNOSTIC
  /*
   * Page or buffer structure gets a reference.
   */
  void
  vholdl(vp)
          struct vnode *vp;
  {
  
          /*
           * If it is on the freelist and the hold count is currently
           * zero, move it to the hold list. The test of the back
           * pointer and the use reference count of zero is because
           * it will be removed from a free list by getnewvnode,
           * but will not have its reference count incremented until
           * after calling vgone. If the reference count were
           * incremented first, vgone would (incorrectly) try to
           * close the previous instance of the underlying object.
           * So, the back pointer is explicitly set to `0xdeadb' in
           * getnewvnode after removing it from a freelist to ensure
           * that we do not try to move it here.
           */
          if ((vp->v_freelist.tqe_prev != (struct vnode **)0xdeadb) &&
              vp->v_holdcnt == 0 && vp->v_usecount == 0) {
                  simple_lock(&vnode_free_list_slock);
                  TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
                  TAILQ_INSERT_TAIL(&vnode_hold_list, vp, v_freelist);
                  simple_unlock(&vnode_free_list_slock);
          }
          vp->v_holdcnt++;
  }
  
  /*
   * Page or buffer structure frees a reference.
   */
  void
  holdrelel(vp)
          struct vnode *vp;
  {
  
          if (vp->v_holdcnt <= 0)
                  panic("holdrelel: holdcnt vp %p", vp);
          vp->v_holdcnt--;
  
          /*
           * If it is on the holdlist and the hold count drops to
           * zero, move it to the free list. The test of the back
           * pointer and the use reference count of zero is because
           * it will be removed from a free list by getnewvnode,
           * but will not have its reference count incremented until
           * after calling vgone. If the reference count were
           * incremented first, vgone would (incorrectly) try to
           * close the previous instance of the underlying object.
           * So, the back pointer is explicitly set to `0xdeadb' in
           * getnewvnode after removing it from a freelist to ensure
           * that we do not try to move it here.
           */
  
          if ((vp->v_freelist.tqe_prev != (struct vnode **)0xdeadb) &&
              vp->v_holdcnt == 0 && vp->v_usecount == 0) {
                  simple_lock(&vnode_free_list_slock);
                  TAILQ_REMOVE(&vnode_hold_list, vp, v_freelist);
                  TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
                  simple_unlock(&vnode_free_list_slock);
          }
  }
  
  /*
   * Vnode reference.
   */
  void
  vref(vp)
          struct vnode *vp;
  {
  
          simple_lock(&vp->v_interlock);
          if (vp->v_usecount <= 0)
                  panic("vref used where vget required, vp %p", vp);
          vp->v_usecount++;
  #ifdef DIAGNOSTIC
          if (vp->v_usecount == 0) {
                  vprint("vref", vp);
                  panic("vref: usecount overflow, vp %p", vp);
          }
  #endif
          simple_unlock(&vp->v_interlock);
  }
  #endif /* DIAGNOSTIC */
  
  /*
   * Remove any vnodes in the vnode table belonging to mount point mp.
   *
   * If FORCECLOSE is not specified, there should not be any active ones,
   * return error if any are found (nb: this is a user error, not a
   * system error). If FORCECLOSE is specified, detach any active vnodes
   * that are found.
   *
   * If WRITECLOSE is set, only flush out regular file vnodes open for
   * writing.
   *
   * SKIPSYSTEM causes any vnodes marked V_SYSTEM to be skipped.
   */
  #ifdef DEBUG
  int busyprt = 0;        /* print out busy vnodes */
  struct ctldebug debug1 = { "busyprt", &busyprt };
  #endif
  
  int
  vflush(mp, skipvp, flags)
          struct mount *mp;
          struct vnode *skipvp;
          int flags;
  {
          struct proc *p = curproc;       /* XXX */
          struct vnode *vp, *nvp;
          int busy = 0;
  
          simple_lock(&mntvnode_slock);
  loop:
          for (vp = LIST_FIRST(&mp->mnt_vnodelist); vp; vp = nvp) {
                  if (vp->v_mount != mp)
                          goto loop;
                  nvp = LIST_NEXT(vp, v_mntvnodes);
                  /*
                   * Skip over a selected vnode.
                   */
                  if (vp == skipvp)
                          continue;
                  simple_lock(&vp->v_interlock);
                  /*
                   * Skip over a vnodes marked VSYSTEM.
                   */
                  if ((flags & SKIPSYSTEM) && (vp->v_flag & VSYSTEM)) {
                          simple_unlock(&vp->v_interlock);
                          continue;
                  }
                  /*
                   * If WRITECLOSE is set, only flush out regular file
                   * vnodes open for writing.
                   */
                  if ((flags & WRITECLOSE) &&
                      (vp->v_writecount == 0 || vp->v_type != VREG)) {
                          simple_unlock(&vp->v_interlock);
                          continue;
                  }
                  /*
                   * With v_usecount == 0, all we need to do is clear
                   * out the vnode data structures and we are done.
                   */
                  if (vp->v_usecount == 0) {
                          simple_unlock(&mntvnode_slock);
                          vgonel(vp, p);
                          simple_lock(&mntvnode_slock);
                          continue;
                  }
                  /*
                   * If FORCECLOSE is set, forcibly close the vnode.
                   * For block or character devices, revert to an
                   * anonymous device. For all other files, just kill them.
                   */
                  if (flags & FORCECLOSE) {
                          simple_unlock(&mntvnode_slock);
                          if (vp->v_type != VBLK && vp->v_type != VCHR) {
                                  vgonel(vp, p);
                          } else {
                                  vclean(vp, 0, p);
                                  vp->v_op = spec_vnodeop_p;
                                  insmntque(vp, (struct mount *)0);
                          }
                          simple_lock(&mntvnode_slock);
                          continue;
                  }
  #ifdef DEBUG
                  if (busyprt)
                          vprint("vflush: busy vnode", vp);
  #endif
                  simple_unlock(&vp->v_interlock);
                  busy++;
          }
          simple_unlock(&mntvnode_slock);
          if (busy)
                  return (EBUSY);
          return (0);
  }
  
  /*
   * Disassociate the underlying file system from a vnode.
   */
  void
  vclean(vp, flags, p)
          struct vnode *vp;
          int flags;
          struct proc *p;
  {
          struct mount *mp;
          int active;
  
          LOCK_ASSERT(simple_lock_held(&vp->v_interlock));
  
          /*
           * 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.
           */
  
          if ((active = vp->v_usecount) != 0) {
                  vp->v_usecount++;
  #ifdef DIAGNOSTIC
                  if (vp->v_usecount == 0) {
                          vprint("vclean", vp);
                          panic("vclean: usecount overflow");
                  }
  #endif
          }
  
          /*
           * Prevent the vnode from being recycled or
           * brought into use while we clean it out.
           */
          if (vp->v_flag & VXLOCK)
                  panic("vclean: deadlock, vp %p", vp);
          vp->v_flag |= VXLOCK;
          if (vp->v_flag & VEXECMAP) {
                  uvmexp.execpages -= vp->v_uobj.uo_npages;
                  uvmexp.filepages += vp->v_uobj.uo_npages;
          }
          vp->v_flag &= ~(VTEXT|VEXECMAP);
  
          /*
           * Even if the count is zero, the VOP_INACTIVE routine may still
           * have the object locked while it cleans it out. The VOP_LOCK
           * ensures that the VOP_INACTIVE routine is done with its work.
           * For active vnodes, it ensures that no other activity can
           * occur while the underlying object is being cleaned out.
           */
          VOP_LOCK(vp, LK_DRAIN | LK_INTERLOCK);
  
          /*
           * Clean out any cached data associated with the vnode.
           * If special device, remove it from special device alias list.
           * if it is on one.
           */
          if (flags & DOCLOSE) {
                  int error;
                  struct vnode *vq, *vx;
  
                  vn_start_write(vp, &mp, V_WAIT | V_LOWER);
                  error = vinvalbuf(vp, V_SAVE, NOCRED, p, 0, 0);
                  vn_finished_write(mp, V_LOWER);
                  if (error)
                          error = vinvalbuf(vp, 0, NOCRED, p, 0, 0);
                  KASSERT(error == 0);
                  KASSERT((vp->v_flag & VONWORKLST) == 0);
  
                  if (active)
                          VOP_CLOSE(vp, FNONBLOCK, NOCRED, NULL);
  
                  if ((vp->v_type == VBLK || vp->v_type == VCHR) &&
                      vp->v_specinfo != 0) {
                          simple_lock(&spechash_slock);
                          if (vp->v_hashchain != NULL) {
                                  if (*vp->v_hashchain == vp) {
                                          *vp->v_hashchain = vp->v_specnext;
                                  } else {
                                          for (vq = *vp->v_hashchain; vq;
                                               vq = vq->v_specnext) {
                                                  if (vq->v_specnext != vp)
                                                          continue;
                                                  vq->v_specnext = vp->v_specnext;
                                                  break;
                                          }
                                          if (vq == NULL)
                                                  panic("missing bdev");
                                  }
                                  if (vp->v_flag & VALIASED) {
                                          vx = NULL;
                                                  for (vq = *vp->v_hashchain; vq;
                                                       vq = vq->v_specnext) {
                                                  if (vq->v_rdev != vp->v_rdev ||
                                                      vq->v_type != vp->v_type)
                                                          continue;
                                                  if (vx)
                                                          break;
                                                  vx = vq;
                                          }
                                          if (vx == NULL)
                                                  panic("missing alias");
                                          if (vq == NULL)
                                                  vx->v_flag &= ~VALIASED;
                                          vp->v_flag &= ~VALIASED;
                                  }
                          }
                          simple_unlock(&spechash_slock);
                          FREE(vp->v_specinfo, M_VNODE);
                          vp->v_specinfo = NULL;
                  }
          }
          LOCK_ASSERT(!simple_lock_held(&vp->v_interlock));
  
          /*
           * If purging an active vnode, it must be closed and
           * deactivated before being reclaimed. Note that the
           * VOP_INACTIVE will unlock the vnode.
           */
          if (active) {
                  VOP_INACTIVE(vp, p);
          } else {
                  /*
                   * Any other processes trying to obtain this lock must first
                   * wait for VXLOCK to clear, then call the new lock operation.
                   */
                  VOP_UNLOCK(vp, 0);
          }
          /*
           * Reclaim the vnode.
           */
          if (VOP_RECLAIM(vp, p))
                  panic("vclean: cannot reclaim, vp %p", vp);
          if (active) {
                  /*
                   * Inline copy of vrele() since VOP_INACTIVE
                   * has already been called.
                   */
                  simple_lock(&vp->v_interlock);
                  if (--vp->v_usecount <= 0) {
  #ifdef DIAGNOSTIC
                          if (vp->v_usecount < 0 || vp->v_writecount != 0) {
                                  vprint("vclean: bad ref count", vp);
                                  panic("vclean: ref cnt");
                          }
  #endif
                          /*
                           * Insert at tail of LRU list.
                           */
  
                          simple_unlock(&vp->v_interlock);
                          simple_lock(&vnode_free_list_slock);
  #ifdef DIAGNOSTIC
                          if (vp->v_holdcnt > 0)
                                  panic("vclean: not clean, vp %p", vp);
  #endif
                          TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
                          simple_unlock(&vnode_free_list_slock);
                  } else
                          simple_unlock(&vp->v_interlock);
          }
  
          KASSERT(vp->v_uobj.uo_npages == 0);
          cache_purge(vp);
  
          /*
           * Done with purge, notify sleepers of the grim news.
           */
          vp->v_op = dead_vnodeop_p;
          vp->v_tag = VT_NON;
          simple_lock(&vp->v_interlock);
          VN_KNOTE(vp, NOTE_REVOKE);      /* FreeBSD has this in vn_pollgone() */
          vp->v_flag &= ~VXLOCK;
          if (vp->v_flag & VXWANT) {
                  vp->v_flag &= ~VXWANT;
                  simple_unlock(&vp->v_interlock);
                  wakeup((caddr_t)vp);
          } else
                  simple_unlock(&vp->v_interlock);
  }
  
  /*
   * Recycle an unused vnode to the front of the free list.
   * Release the passed interlock if the vnode will be recycled.
   */
  int
  vrecycle(vp, inter_lkp, p)
          struct vnode *vp;
          struct simplelock *inter_lkp;
          struct proc *p;
  {
  
          simple_lock(&vp->v_interlock);
          if (vp->v_usecount == 0) {
                  if (inter_lkp)
                          simple_unlock(inter_lkp);
                  vgonel(vp, p);
                  return (1);
          }
          simple_unlock(&vp->v_interlock);
          return (0);
  }
  
  /*
   * Eliminate all activity associated with a vnode
   * in preparation for reuse.
   */
  void
  vgone(vp)
          struct vnode *vp;
  {
          struct proc *p = curproc;       /* XXX */
  
          simple_lock(&vp->v_interlock);
          vgonel(vp, p);
  }
  
  /*
   * vgone, with the vp interlock held.
   */
  void
  vgonel(vp, p)
          struct vnode *vp;
          struct proc *p;
  {
  
          LOCK_ASSERT(simple_lock_held(&vp->v_interlock));
  
          /*
           * If a vgone (or vclean) is already in progress,
           * wait until it is done and return.
           */
  
          if (vp->v_flag & VXLOCK) {
                  vp->v_flag |= VXWANT;
                  ltsleep(vp, PINOD | PNORELOCK, "vgone", 0, &vp->v_interlock);
                  return;
          }
  
          /*
           * Clean out the filesystem specific data.
           */
  
          vclean(vp, DOCLOSE, p);
          KASSERT((vp->v_flag & VONWORKLST) == 0);
  
          /*
           * Delete from old mount point vnode list, if on one.
           */
  
          if (vp->v_mount != NULL)
                  insmntque(vp, (struct mount *)0);
  
          /*
           * The test of the back pointer and the reference count of
           * zero is because it will be removed from the free list by
           * getcleanvnode, but will not have its reference count
           * incremented until after calling vgone. If the reference
           * count were incremented first, vgone would (incorrectly)
           * try to close the previous instance of the underlying object.
           * So, the back pointer is explicitly set to `0xdeadb' in
           * getnewvnode after removing it from the freelist to ensure
           * that we do not try to move it here.
           */
  
          vp->v_type = VBAD;
          if (vp->v_usecount == 0) {
                  boolean_t dofree;
  
                  simple_lock(&vnode_free_list_slock);
                  if (vp->v_holdcnt > 0)
                          panic("vgonel: not clean, vp %p", vp);
                  /*
                   * if it isn't on the freelist, we're called by getcleanvnode
                   * and vnode is being re-used.  otherwise, we'll free it.
                   */
                  dofree = vp->v_freelist.tqe_prev != (struct vnode **)0xdeadb;
                  if (dofree) {
                          TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
                          numvnodes--;
                  }
                  simple_unlock(&vnode_free_list_slock);
                  if (dofree)
                          pool_put(&vnode_pool, vp);
          }
  }
  
  /*
   * Lookup a vnode by device number.
   */
  int
  vfinddev(dev, type, vpp)
          dev_t dev;
          enum vtype type;
          struct vnode **vpp;
  {
          struct vnode *vp;
          int rc = 0;
  
          simple_lock(&spechash_slock);
          for (vp = speclisth[SPECHASH(dev)]; vp; vp = vp->v_specnext) {
                  if (dev != vp->v_rdev || type != vp->v_type)
                          continue;
                  *vpp = vp;
                  rc = 1;
                  break;
          }
          simple_unlock(&spechash_slock);
          return (rc);
  }
  
  /*
   * Revoke all the vnodes corresponding to the specified minor number
   * range (endpoints inclusive) of the specified major.
   */
  void
  vdevgone(maj, minl, minh, type)
          int maj, minl, minh;
          enum vtype type;
  {
          struct vnode *vp;
          int mn;
  
          for (mn = minl; mn <= minh; mn++)
                  if (vfinddev(makedev(maj, mn), type, &vp))
                          VOP_REVOKE(vp, REVOKEALL);
  }
  
  /*
   * Calculate the total number of references to a special device.
   */
  int
  vcount(vp)
          struct vnode *vp;
  {
          struct vnode *vq, *vnext;
          int count;
  
  loop:
          if ((vp->v_flag & VALIASED) == 0)
                  return (vp->v_usecount);
          simple_lock(&spechash_slock);
          for (count = 0, vq = *vp->v_hashchain; vq; vq = vnext) {
                  vnext = vq->v_specnext;
                  if (vq->v_rdev != vp->v_rdev || vq->v_type != vp->v_type)
                          continue;
                  /*
                   * Alias, but not in use, so flush it out.
                   */
                  if (vq->v_usecount == 0 && vq != vp &&
                      (vq->v_flag & VXLOCK) == 0) {
                          simple_unlock(&spechash_slock);
                          vgone(vq);
                          goto loop;
                  }
                  count += vq->v_usecount;
          }
          simple_unlock(&spechash_slock);
          return (count);
  }
  
  /*
   * Print out a description of a vnode.
   */
  const char * const vnode_types[] = {
          "VNON",
          "VREG",
          "VDIR",
          "VBLK",
          "VCHR",
          "VLNK",
          "VSOCK",
          "VFIFO",
          "VBAD"
  };
  
  void
  vprint(label, vp)
          char *label;
          struct vnode *vp;
  {
          char buf[96];
  
          if (label != NULL)
                  printf("%s: ", label);
          printf("tag %d type %s, usecount %d, writecount %ld, refcount %ld,",
              vp->v_tag, vnode_types[vp->v_type],
              vp->v_usecount, vp->v_writecount, vp->v_holdcnt);
          buf[0] = '\0';
          if (vp->v_flag & VROOT)
                  strlcat(buf, "|VROOT", sizeof(buf));
          if (vp->v_flag & VTEXT)
                  strlcat(buf, "|VTEXT", sizeof(buf));
          if (vp->v_flag & VEXECMAP)
                  strlcat(buf, "|VEXECMAP", sizeof(buf));
          if (vp->v_flag & VSYSTEM)
                  strlcat(buf, "|VSYSTEM", sizeof(buf));
          if (vp->v_flag & VXLOCK)
                  strlcat(buf, "|VXLOCK", sizeof(buf));
          if (vp->v_flag & VXWANT)
                  strlcat(buf, "|VXWANT", sizeof(buf));
          if (vp->v_flag & VBWAIT)
                  strlcat(buf, "|VBWAIT", sizeof(buf));
          if (vp->v_flag & VALIASED)
                  strlcat(buf, "|VALIASED", sizeof(buf));
          if (buf[0] != '\0')
                  printf(" flags (%s)", &buf[1]);
          if (vp->v_data == NULL) {
                  printf("\n");
          } else {
                  printf("\n\t");
                  VOP_PRINT(vp);
          }
  }
  
  #ifdef DEBUG
  /*
   * List all of the locked vnodes in the system.
   * Called when debugging the kernel.
   */
  void
  printlockedvnodes()
  {
          struct mount *mp, *nmp;
          struct vnode *vp;
  
          printf("Locked vnodes\n");
          simple_lock(&mountlist_slock);
          for (mp = CIRCLEQ_FIRST(&mountlist); mp != (void *)&mountlist;
               mp = nmp) {
                  if (vfs_busy(mp, LK_NOWAIT, &mountlist_slock)) {
                          nmp = CIRCLEQ_NEXT(mp, mnt_list);
                          continue;
                  }
                  LIST_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes) {
                          if (VOP_ISLOCKED(vp))
                                  vprint(NULL, vp);
                  }
                  simple_lock(&mountlist_slock);
                  nmp = CIRCLEQ_NEXT(mp, mnt_list);
                  vfs_unbusy(mp);
          }
          simple_unlock(&mountlist_slock);
  }
  #endif
  
  /*
   * sysctl helper routine for vfs.generic.conf lookups.
   */
  #if defined(COMPAT_09) || defined(COMPAT_43) || defined(COMPAT_44)
  static int
  sysctl_vfs_generic_conf(SYSCTLFN_ARGS)
  {
          struct vfsconf vfc;
          extern const char * const mountcompatnames[];
          extern int nmountcompatnames;
          struct sysctlnode node;
          struct vfsops *vfsp;
          u_int vfsnum;
  
          if (namelen != 1)
                  return (ENOTDIR);
          vfsnum = name[0];
          if (vfsnum >= nmountcompatnames ||
              mountcompatnames[vfsnum] == NULL)
                  return (EOPNOTSUPP);
          vfsp = vfs_getopsbyname(mountcompatnames[vfsnum]);
          if (vfsp == NULL)
                  return (EOPNOTSUPP);
  
          vfc.vfc_vfsops = vfsp;
          strncpy(vfc.vfc_name, vfsp->vfs_name, MFSNAMELEN);
          vfc.vfc_typenum = vfsnum;
          vfc.vfc_refcount = vfsp->vfs_refcount;
          vfc.vfc_flags = 0;
          vfc.vfc_mountroot = vfsp->vfs_mountroot;
          vfc.vfc_next = NULL;
  
          node = *rnode;
          node.sysctl_data = &vfc;
          return (sysctl_lookup(SYSCTLFN_CALL(&node)));
  }
  #endif
  
  /*
   * Top level filesystem related information gathering.
   */
  SYSCTL_SETUP(sysctl_vfs_setup, "sysctl vfs subtree setup")
  {
  #if defined(COMPAT_09) || defined(COMPAT_43) || defined(COMPAT_44)
          extern int nmountcompatnames;
  #endif
  
          sysctl_createv(clog, 0, NULL, NULL,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_NODE, "vfs", NULL,
                         NULL, 0, NULL, 0,
                         CTL_VFS, CTL_EOL);
          sysctl_createv(clog, 0, NULL, NULL,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_NODE, "generic",
                         SYSCTL_DESCR("Non-specific vfs related information"),
                         NULL, 0, NULL, 0,
                         CTL_VFS, VFS_GENERIC, CTL_EOL);
  
  #if defined(COMPAT_09) || defined(COMPAT_43) || defined(COMPAT_44)
          sysctl_createv(clog, 0, NULL, NULL,
                         CTLFLAG_PERMANENT|CTLFLAG_IMMEDIATE,
                         CTLTYPE_INT, "maxtypenum",
                         SYSCTL_DESCR("Highest valid filesystem type number"),
                         NULL, nmountcompatnames, NULL, 0,
                         CTL_VFS, VFS_GENERIC, VFS_MAXTYPENUM, CTL_EOL);
  #endif
          sysctl_createv(clog, 0, NULL, NULL,
                         CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                         CTLTYPE_INT, "usermount",
                         SYSCTL_DESCR("Whether unprivileged users may mount "
                                      "filesystems"),
                         NULL, 0, &dovfsusermount, 0,
                         CTL_VFS, VFS_GENERIC, VFS_USERMOUNT, CTL_EOL);
  #if defined(COMPAT_09) || defined(COMPAT_43) || defined(COMPAT_44)
          sysctl_createv(clog, 0, NULL, NULL,
                         CTLFLAG_PERMANENT,
                         CTLTYPE_STRUCT, "conf",
                         SYSCTL_DESCR("Filesystem configuration information"),
                         sysctl_vfs_generic_conf, 0, NULL,
                         sizeof(struct vfsconf),
                         CTL_VFS, VFS_GENERIC, VFS_CONF, CTL_EOL);
  #endif
  }
  
  
  int kinfo_vdebug = 1;
  int kinfo_vgetfailed;
  #define KINFO_VNODESLOP 10
  /*
   * Dump vnode list (via sysctl).
   * Copyout address of vnode followed by vnode.
   */
  /* ARGSUSED */
  int
  sysctl_kern_vnode(SYSCTLFN_ARGS)
  {
          char *where = oldp;
          size_t *sizep = oldlenp;
          struct mount *mp, *nmp;
          struct vnode *nvp, *vp;
          char *bp = where, *savebp;
          char *ewhere;
          int error;
  
          if (namelen != 0)
                  return (EOPNOTSUPP);
          if (newp != NULL)
                  return (EPERM);
  
  #define VPTRSZ  sizeof(struct vnode *)
  #define VNODESZ sizeof(struct vnode)
          if (where == NULL) {
                  *sizep = (numvnodes + KINFO_VNODESLOP) * (VPTRSZ + VNODESZ);
                  return (0);
          }
          ewhere = where + *sizep;
  
          simple_lock(&mountlist_slock);
          for (mp = CIRCLEQ_FIRST(&mountlist); mp != (void *)&mountlist;
               mp = nmp) {
                  if (vfs_busy(mp, LK_NOWAIT, &mountlist_slock)) {
                          nmp = CIRCLEQ_NEXT(mp, mnt_list);
                          continue;
                  }
                  savebp = bp;
  again:
                  simple_lock(&mntvnode_slock);
                  for (vp = LIST_FIRST(&mp->mnt_vnodelist);
                       vp != NULL;
                       vp = nvp) {
                          /*
                           * Check that the vp is still associated with
                           * this filesystem.  RACE: could have been
                           * recycled onto the same filesystem.
                           */
                          if (vp->v_mount != mp) {
                                  simple_unlock(&mntvnode_slock);
                                  if (kinfo_vdebug)
                                          printf("kinfo: vp changed\n");
                                  bp = savebp;
                                  goto again;
                          }
                          nvp = LIST_NEXT(vp, v_mntvnodes);
                          if (bp + VPTRSZ + VNODESZ > ewhere) {
                                  simple_unlock(&mntvnode_slock);
                                  *sizep = bp - where;
                                  return (ENOMEM);
                          }
                          simple_unlock(&mntvnode_slock);
                          if ((error = copyout((caddr_t)&vp, bp, VPTRSZ)) ||
                             (error = copyout((caddr_t)vp, bp + VPTRSZ, VNODESZ)))
                                  return (error);
                          bp += VPTRSZ + VNODESZ;
                          simple_lock(&mntvnode_slock);
                  }
                  simple_unlock(&mntvnode_slock);
                  simple_lock(&mountlist_slock);
                  nmp = CIRCLEQ_NEXT(mp, mnt_list);
                  vfs_unbusy(mp);
          }
          simple_unlock(&mountlist_slock);
  
          *sizep = bp - where;
          return (0);
  }
  
  /*
   * Check to see if a filesystem is mounted on a block device.
   */
  int
  vfs_mountedon(vp)
          struct vnode *vp;
  {
          struct vnode *vq;
          int error = 0;
  
          if (vp->v_specmountpoint != NULL)
                  return (EBUSY);
          if (vp->v_flag & VALIASED) {
                  simple_lock(&spechash_slock);
                  for (vq = *vp->v_hashchain; vq; vq = vq->v_specnext) {
                          if (vq->v_rdev != vp->v_rdev ||
                              vq->v_type != vp->v_type)
                                  continue;
                          if (vq->v_specmountpoint != NULL) {
                                  error = EBUSY;
                                  break;
                          }
                  }
                  simple_unlock(&spechash_slock);
          }
          return (error);
  }
  
  static int
  sacheck(struct sockaddr *sa)
  {
          switch (sa->sa_family) {
  #ifdef INET
          case AF_INET: {
                  struct sockaddr_in *sin = (struct sockaddr_in *)sa;
                  char *p = (char *)sin->sin_zero;
                  size_t i;
  
                  if (sin->sin_len != sizeof(*sin))
                          return -1;
                  if (sin->sin_port != 0)
                          return -1;
                  for (i = 0; i < sizeof(sin->sin_zero); i++)
                          if (*p++ != '\0')
                                  return -1;
                  return 0;
          }
  #endif
  #ifdef INET6
          case AF_INET6: {
                  struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sa;
  
                  if (sin6->sin6_len != sizeof(*sin6))
                          return -1;
                  if (sin6->sin6_port != 0)
                          return -1;
                  return 0;
          }
  #endif
          default:
                  return -1;
          }
  }
  
  /*
   * 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(mp, nep, argp)
          struct mount *mp;
          struct netexport *nep;
          struct export_args *argp;
  {
          struct netcred *np, *enp;
          struct radix_node_head *rnh;
          int i;
          struct sockaddr *saddr, *smask = 0;
          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;
                  crcvt(&np->netc_anon, &argp->ex_anon);
                  np->netc_anon.cr_ref = 1;
                  mp->mnt_flag |= MNT_DEFEXPORTED;
                  return (0);
          }
  
          if (argp->ex_addrlen > MLEN || argp->ex_masklen > MLEN)
                  return (EINVAL);
  
          i = sizeof(struct netcred) + argp->ex_addrlen + argp->ex_masklen;
          np = (struct netcred *)malloc(i, M_NETADDR, M_WAITOK);
          memset((caddr_t)np, 0, i);
          saddr = (struct sockaddr *)(np + 1);
          error = copyin(argp->ex_addr, (caddr_t)saddr, argp->ex_addrlen);
          if (error)
                  goto out;
          if (saddr->sa_len > argp->ex_addrlen)
                  saddr->sa_len = argp->ex_addrlen;
          if (sacheck(saddr) == -1)
                  return EINVAL;
          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;
                  if (smask->sa_family != saddr->sa_family)
                          return EINVAL;
                  if (sacheck(smask) == -1)
                          return EINVAL;
          }
          i = saddr->sa_family;
          if ((rnh = nep->ne_rtable[i]) == 0) {
                  /*
                   * Seems silly to initialize every AF when most are not
                   * used, do so on demand here
                   */
                  for (dom = domains; dom; dom = dom->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]) == 0) {
                          error = ENOBUFS;
                          goto out;
                  }
          }
  
          enp = (struct netcred *)(*rnh->rnh_addaddr)(saddr, smask, rnh,
              np->netc_rnodes);
          if (enp != np) {
                  if (enp == NULL) {
                          enp = (struct netcred *)(*rnh->rnh_lookup)(saddr,
                              smask, rnh);
                          if (enp == NULL) {
                                  error = EPERM;
                                  goto out;
                          }
                  } else
                          enp->netc_refcnt++;
  
                  goto check;
          } else
                  enp->netc_refcnt = 1;
  
          np->netc_exflags = argp->ex_flags;
          crcvt(&np->netc_anon, &argp->ex_anon);
          np->netc_anon.cr_ref = 1;
          return 0;
  check:
          if (enp->netc_exflags != argp->ex_flags ||
              crcmp(&enp->netc_anon, &argp->ex_anon) != 0)
                  error = EPERM;
          else
                  error = 0;
  out:
          free(np, M_NETADDR);
          return error;
  }
  
  /* ARGSUSED */
  static int
  vfs_free_netcred(rn, w)
          struct radix_node *rn;
          void *w;
  {
          struct radix_node_head *rnh = (struct radix_node_head *)w;
          struct netcred *np = (struct netcred *)(void *)rn;
  
          (*rnh->rnh_deladdr)(rn->rn_key, rn->rn_mask, rnh);
          if (--(np->netc_refcnt) <= 0)
                  free(np, M_NETADDR);
          return (0);
  }
  
  /*
   * Free the net address hash lists that are hanging off the mount points.
   */
  static void
  vfs_free_addrlist(nep)
          struct netexport *nep;
  {
          int i;
          struct radix_node_head *rnh;
  
          for (i = 0; i <= AF_MAX; i++)
                  if ((rnh = nep->ne_rtable[i]) != NULL) {
                          (*rnh->rnh_walktree)(rnh, vfs_free_netcred, rnh);
                          free((caddr_t)rnh, M_RTABLE);
                          nep->ne_rtable[i] = 0;
                  }
  }
  
  int
  vfs_export(mp, nep, argp)
          struct mount *mp;
          struct netexport *nep;
          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)) != 0)
                          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(mp, nep, argp)
          struct mount *mp;
          struct netexport *nep;
          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) {
                                  FREE(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.
           */
          memset((caddr_t)&nfs_pub.np_handle, 0, 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) {
                  MALLOC(nfs_pub.np_index, char *, MAXNAMLEN + 1, M_TEMP,
                      M_WAITOK);
                  error = copyinstr(argp->ex_indexfile, nfs_pub.np_index,
                      MAXNAMLEN, (size_t *)0);
                  if (!error) {
                          /*
                           * Check for illegal filenames.
                           */
                          for (cp = nfs_pub.np_index; *cp; cp++) {
                                  if (*cp == '/') {
                                          error = EINVAL;
                                          break;
                                  }
                          }
                  }
                  if (error) {
                          FREE(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(mp, nep, nam)
          struct mount *mp;
          struct netexport *nep;
          struct mbuf *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 = mtod(nam, struct sockaddr *);
                          rnh = nep->ne_rtable[saddr->sa_family];
                          if (rnh != NULL) {
                                  np = (struct netcred *)
                                          (*rnh->rnh_matchaddr)((caddr_t)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);
  }
  
  /*
   * 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(type, file_mode, uid, gid, acc_mode, cred)
          enum vtype type;
          mode_t file_mode;
          uid_t uid;
          gid_t gid;
          mode_t acc_mode;
          struct ucred *cred;
  {
          mode_t mask;
  
          /*
           * Super-user always gets read/write access, but execute access depends
           * on at least one execute bit being set.
           */
          if (cred->cr_uid == 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. */
          if (cred->cr_gid == gid || groupmember(gid, cred)) {
                  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);
  }
  
  /*
   * Unmount all file systems.
   * We traverse the list in reverse order under the assumption that doing so
   * will avoid needing to worry about dependencies.
   */
  void
  vfs_unmountall(p)
          struct proc *p;
  {
          struct mount *mp, *nmp;
          int allerror, error;
  
          for (allerror = 0,
               mp = mountlist.cqh_last; mp != (void *)&mountlist; mp = nmp) {
                  nmp = mp->mnt_list.cqe_prev;
  #ifdef DEBUG
                  printf("unmounting %s (%s)...\n",
                      mp->mnt_stat.f_mntonname, mp->mnt_stat.f_mntfromname);
  #endif
                  /*
                   * XXX Freeze syncer.  Must do this before locking the
                   * mount point.  See dounmount() for details.
                   */
                  lockmgr(&syncer_lock, LK_EXCLUSIVE, NULL);
                  if (vfs_busy(mp, 0, 0)) {
                          lockmgr(&syncer_lock, LK_RELEASE, NULL);
                          continue;
                  }
                  if ((error = dounmount(mp, MNT_FORCE, p)) != 0) {
                          printf("unmount of %s failed with error %d\n",
                              mp->mnt_stat.f_mntonname, error);
                          allerror = 1;
                  }
          }
          if (allerror)
                  printf("WARNING: some file systems would not unmount\n");
  }
  
  extern struct simplelock bqueue_slock; /* XXX */
  
  /*
   * Sync and unmount file systems before shutting down.
   */
  void
  vfs_shutdown()
  {
          struct lwp *l = curlwp;
          struct proc *p;
  
          /* XXX we're certainly not running in proc0's context! */
          if (l == NULL || (p = l->l_proc) == NULL)
                  p = &proc0;
  
          printf("syncing disks... ");
  
          /* remove user process from run queue */
          suspendsched();
          (void) spl0();
  
          /* avoid coming back this way again if we panic. */
          doing_shutdown = 1;
  
          sys_sync(l, NULL, NULL);
  
          /* Wait for sync to finish. */
          if (buf_syncwait() != 0) {
  #if defined(DDB) && defined(DEBUG_HALT_BUSY)
                  Debugger();
  #endif
                  printf("giving up\n");
                  return;
          } else
                  printf("done\n");
  
          /*
           * If we've panic'd, don't make the situation potentially
           * worse by unmounting the file systems.
           */
          if (panicstr != NULL)
                  return;
  
          /* Release inodes held by texts before update. */
  #ifdef notdef
          vnshutdown();
  #endif
          /* Unmount file systems. */
          vfs_unmountall(p);
  }
  
  /*
   * Mount the root file system.  If the operator didn't specify a
   * file system to use, try all possible file systems until one
   * succeeds.
   */
  int
  vfs_mountroot()
  {
          struct vfsops *v;
  
          if (root_device == NULL)
                  panic("vfs_mountroot: root device unknown");
  
          switch (root_device->dv_class) {
          case DV_IFNET:
                  if (rootdev != NODEV)
                          panic("vfs_mountroot: rootdev set for DV_IFNET "
                              "(0x%08x -> %d,%d)", rootdev,
                              major(rootdev), minor(rootdev));
                  break;
  
          case DV_DISK:
                  if (rootdev == NODEV)
                          panic("vfs_mountroot: rootdev not set for DV_DISK");
                  break;
  
          default:
                  printf("%s: inappropriate for root file system\n",
                      root_device->dv_xname);
                  return (ENODEV);
          }
  
          /*
           * If user specified a file system, use it.
           */
          if (mountroot != NULL)
                  return ((*mountroot)());
  
          /*
           * Try each file system currently configured into the kernel.
           */
          for (v = LIST_FIRST(&vfs_list); v != NULL; v = LIST_NEXT(v, vfs_list)) {
                  if (v->vfs_mountroot == NULL)
                          continue;
  #ifdef DEBUG
                  aprint_normal("mountroot: trying %s...\n", v->vfs_name);
  #endif
                  if ((*v->vfs_mountroot)() == 0) {
                          aprint_normal("root file system type: %s\n",
                              v->vfs_name);
                          break;
                  }
          }
  
          if (v == NULL) {
                  printf("no file system for %s", root_device->dv_xname);
                  if (root_device->dv_class == DV_DISK)
                          printf(" (dev 0x%x)", rootdev);
                  printf("\n");
                  return (EFTYPE);
          }
          return (0);
  }
  
  /*
   * Given a file system name, look up the vfsops for that
   * file system, or return NULL if file system isn't present
   * in the kernel.
   */
  struct vfsops *
  vfs_getopsbyname(name)
          const char *name;
  {
          struct vfsops *v;
  
          for (v = LIST_FIRST(&vfs_list); v != NULL; v = LIST_NEXT(v, vfs_list)) {
                  if (strcmp(v->vfs_name, name) == 0)
                          break;
          }
  
          return (v);
  }
  
  /*
   * Establish a file system and initialize it.
   */
  int
  vfs_attach(vfs)
          struct vfsops *vfs;
  {
          struct vfsops *v;
          int error = 0;
  
  
          /*
           * Make sure this file system doesn't already exist.
           */
          LIST_FOREACH(v, &vfs_list, vfs_list) {
                  if (strcmp(vfs->vfs_name, v->vfs_name) == 0) {
                          error = EEXIST;
                          goto out;
                  }
          }
  
          /*
           * Initialize the vnode operations for this file system.
           */
          vfs_opv_init(vfs->vfs_opv_descs);
  
          /*
           * Now initialize the file system itself.
           */
          (*vfs->vfs_init)();
  
          /*
           * ...and link it into the kernel's list.
           */
          LIST_INSERT_HEAD(&vfs_list, vfs, vfs_list);
  
          /*
           * Sanity: make sure the reference count is 0.
           */
          vfs->vfs_refcount = 0;
  
   out:
          return (error);
  }
  
  /*
   * Remove a file system from the kernel.
   */
  int
  vfs_detach(vfs)
          struct vfsops *vfs;
  {
          struct vfsops *v;
  
          /*
           * Make sure no one is using the filesystem.
           */
          if (vfs->vfs_refcount != 0)
                  return (EBUSY);
  
          /*
           * ...and remove it from the kernel's list.
           */
          LIST_FOREACH(v, &vfs_list, vfs_list) {
                  if (v == vfs) {
                          LIST_REMOVE(v, vfs_list);
                          break;
                  }
          }
  
          if (v == NULL)
                  return (ESRCH);
  
          /*
           * Now run the file system-specific cleanups.
           */
          (*vfs->vfs_done)();
  
          /*
           * Free the vnode operations vector.
           */
          vfs_opv_free(vfs->vfs_opv_descs);
          return (0);
  }
  
  void
  vfs_reinit(void)
  {
          struct vfsops *vfs;
  
          LIST_FOREACH(vfs, &vfs_list, vfs_list) {
                  if (vfs->vfs_reinit) {
                          (*vfs->vfs_reinit)();
                  }
          }
  }
  
  /*
   * Request a filesystem to suspend write operations.
   */
  int
  vfs_write_suspend(struct mount *mp, int slpflag, int slptimeo)
  {
          struct proc *p = curproc;       /* XXX */
          int error;
  
          while ((mp->mnt_iflag & IMNT_SUSPEND)) {
                  if (slptimeo < 0)
                          return EWOULDBLOCK;
                  error = tsleep(&mp->mnt_flag, slpflag, "suspwt1", slptimeo);
                  if (error)
                          return error;
          }
          mp->mnt_iflag |= IMNT_SUSPEND;
  
          if (mp->mnt_writeopcountupper > 0)
                  tsleep(&mp->mnt_writeopcountupper, PUSER - 1, "suspwt", 0);
  
          error = VFS_SYNC(mp, MNT_WAIT, p->p_ucred, p);
          if (error) {
                  vfs_write_resume(mp);
                  return error;
          }
          mp->mnt_iflag |= IMNT_SUSPENDLOW;
  
          if (mp->mnt_writeopcountlower > 0)
                  tsleep(&mp->mnt_writeopcountlower, PUSER - 1, "suspwt", 0);
          mp->mnt_iflag |= IMNT_SUSPENDED;
  
          return 0;
  }
  
  /*
   * Request a filesystem to resume write operations.
   */
  void
  vfs_write_resume(struct mount *mp)
  {
  
          if ((mp->mnt_iflag & IMNT_SUSPEND) == 0)
                  return;
          mp->mnt_iflag &= ~(IMNT_SUSPEND | IMNT_SUSPENDLOW | IMNT_SUSPENDED);
          wakeup(&mp->mnt_flag);
  }
  
  void
  copy_statfs_info(struct statfs *sbp, const struct mount *mp)
  {
          const struct statfs *mbp;
  
          if (sbp == (mbp = &mp->mnt_stat))
                  return;
  
          sbp->f_oflags = mbp->f_oflags;
          sbp->f_type = mbp->f_type;
          (void)memcpy(&sbp->f_fsid, &mbp->f_fsid, sizeof(sbp->f_fsid));
          sbp->f_owner = mbp->f_owner;
          sbp->f_flags = mbp->f_flags;
          sbp->f_syncwrites = mbp->f_syncwrites;
          sbp->f_asyncwrites = mbp->f_asyncwrites;
          sbp->f_spare[0] = mbp->f_spare[0];
          (void)memcpy(sbp->f_fstypename, mbp->f_fstypename,
              sizeof(sbp->f_fstypename));
          (void)memcpy(sbp->f_mntonname, mbp->f_mntonname,
              sizeof(sbp->f_mntonname));
          (void)memcpy(sbp->f_mntfromname, mp->mnt_stat.f_mntfromname,
              sizeof(sbp->f_mntfromname));
  }
  
  int
  set_statfs_info(const char *onp, int ukon, const char *fromp, int ukfrom,
      struct mount *mp, struct proc *p)
  {
          int error;
          size_t size;
          struct statfs *sfs = &mp->mnt_stat;
          int (*fun)(const void *, void *, size_t, size_t *);
  
          (void)strncpy(mp->mnt_stat.f_fstypename, mp->mnt_op->vfs_name,
              sizeof(mp->mnt_stat.f_fstypename));
  
          if (onp) {
                  struct cwdinfo *cwdi = p->p_cwdi;
                  fun = (ukon == UIO_SYSSPACE) ? copystr : copyinstr;
                  if (cwdi->cwdi_rdir != NULL) {
                          size_t len;
                          char *bp;
                          char *path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
  
                          if (!path) /* XXX can't happen with M_WAITOK */
                                  return ENOMEM;
  
                          bp = path + MAXPATHLEN;
                          *--bp = '\0';
                          error = getcwd_common(cwdi->cwdi_rdir, rootvnode, &bp,
                              path, MAXPATHLEN / 2, 0, p);
                          if (error) {
                                  free(path, M_TEMP);
                                  return error;
                          }
  
                          len = strlen(bp);
                          if (len > sizeof(sfs->f_mntonname) - 1)
                                  len = sizeof(sfs->f_mntonname) - 1;
                          (void)strncpy(sfs->f_mntonname, bp, len);
                          free(path, M_TEMP);
  
                          if (len < sizeof(sfs->f_mntonname) - 1) {
                                  error = (*fun)(onp, &sfs->f_mntonname[len],
                                      sizeof(sfs->f_mntonname) - len - 1, &size);
                                  if (error)
                                          return error;
                                  size += len;
                          } else {
                                  size = len;
                          }
                  } else {
                          error = (*fun)(onp, &sfs->f_mntonname,
                              sizeof(sfs->f_mntonname) - 1, &size);
                          if (error)
                                  return error;
                  }
                  (void)memset(sfs->f_mntonname + size, 0,
                      sizeof(sfs->f_mntonname) - size);
          }
  
          if (fromp) {
                  fun = (ukfrom == UIO_SYSSPACE) ? copystr : copyinstr;
                  error = (*fun)(fromp, sfs->f_mntfromname,
                      sizeof(sfs->f_mntfromname) - 1, &size);
                  if (error)
                          return error;
                  (void)memset(sfs->f_mntfromname + size, 0,
                      sizeof(sfs->f_mntfromname) - size);
          }
          return 0;
  }
  
  #ifdef DDB
  const char buf_flagbits[] =
          "\2\1AGE\2NEEDCOMMIT\3ASYNC\4BAD\5BUSY\6SCANNED\7CALL\10DELWRI"
          "\11DIRTY\12DONE\13EINTR\14ERROR\15GATHERED\16INVAL\17LOCKED\20NOCACHE"
          "\21ORDERED\22CACHE\23PHYS\24RAW\25READ\26TAPE\30WANTED"
          "\32XXX\33VFLUSH";
  
  void
  vfs_buf_print(bp, full, pr)
          struct buf *bp;
          int full;
          void (*pr)(const char *, ...);
  {
          char buf[1024];
  
          (*pr)("  vp %p lblkno 0x%"PRIx64" blkno 0x%"PRIx64" dev 0x%x\n",
                    bp->b_vp, bp->b_lblkno, bp->b_blkno, bp->b_dev);
  
          bitmask_snprintf(bp->b_flags, buf_flagbits, buf, sizeof(buf));
          (*pr)("  error %d flags 0x%s\n", bp->b_error, buf);
  
          (*pr)("  bufsize 0x%lx bcount 0x%lx resid 0x%lx\n",
                    bp->b_bufsize, bp->b_bcount, bp->b_resid);
          (*pr)("  data %p saveaddr %p dep %p\n",
                    bp->b_data, bp->b_saveaddr, LIST_FIRST(&bp->b_dep));
          (*pr)("  iodone %p\n", bp->b_iodone);
  }
  
  
  const char vnode_flagbits[] =
          "\2\1ROOT\2TEXT\3SYSTEM\4ISTTY\5EXECMAP"
          "\11XLOCK\12XWANT\13BWAIT\14ALIASED"
          "\15DIROP\16LAYER\17ONWORKLIST\20DIRTY";
  
  const char * const vnode_tags[] = {
          "VT_NON",
          "VT_UFS",
          "VT_NFS",
          "VT_MFS",
          "VT_MSDOSFS",
          "VT_LFS",
          "VT_LOFS",
          "VT_FDESC",
          "VT_PORTAL",
          "VT_NULL",
          "VT_UMAP",
          "VT_KERNFS",
          "VT_PROCFS",
          "VT_AFS",
          "VT_ISOFS",
          "VT_UNION",
          "VT_ADOSFS",
          "VT_EXT2FS",
          "VT_CODA",
          "VT_FILECORE",
          "VT_NTFS",
          "VT_VFS",
          "VT_OVERLAY",
          "VT_SMBFS"
  };
  
  void
  vfs_vnode_print(vp, full, pr)
          struct vnode *vp;
          int full;
          void (*pr)(const char *, ...);
  {
          char buf[256];
          const char *vtype, *vtag;
  
          uvm_object_printit(&vp->v_uobj, full, pr);
          bitmask_snprintf(vp->v_flag, vnode_flagbits, buf, sizeof(buf));
          (*pr)("\nVNODE flags %s\n", buf);
          (*pr)("mp %p numoutput %d size 0x%llx\n",
                vp->v_mount, vp->v_numoutput, vp->v_size);
  
          (*pr)("data %p usecount %d writecount %ld holdcnt %ld numoutput %d\n",
                vp->v_data, vp->v_usecount, vp->v_writecount,
                vp->v_holdcnt, vp->v_numoutput);
  
          vtype = (vp->v_type >= 0 &&
                   vp->v_type < sizeof(vnode_types) / sizeof(vnode_types[0])) ?
                  vnode_types[vp->v_type] : "UNKNOWN";
          vtag = (vp->v_tag >= 0 &&
                  vp->v_tag < sizeof(vnode_tags) / sizeof(vnode_tags[0])) ?
                  vnode_tags[vp->v_tag] : "UNKNOWN";
  
          (*pr)("type %s(%d) tag %s(%d) mount %p typedata %p\n",
                vtype, vp->v_type, vtag, vp->v_tag,
                vp->v_mount, vp->v_mountedhere);
  
          if (full) {
                  struct buf *bp;
  
                  (*pr)("clean bufs:\n");
                  LIST_FOREACH(bp, &vp->v_cleanblkhd, b_vnbufs) {
                          (*pr)(" bp %p\n", bp);
                          vfs_buf_print(bp, full, pr);
                  }
  
                  (*pr)("dirty bufs:\n");
                  LIST_FOREACH(bp, &vp->v_dirtyblkhd, b_vnbufs) {
                          (*pr)(" bp %p\n", bp);
                          vfs_buf_print(bp, full, pr);
                  }
          }
  }
  
  void
  vfs_mount_print(mp, full, pr)
          struct mount *mp;
          int full;
          void (*pr)(const char *, ...);
  {
          char sbuf[256];
  
          (*pr)("vnodecovered = %p syncer = %p data = %p\n",
                          mp->mnt_vnodecovered,mp->mnt_syncer,mp->mnt_data);
  
          (*pr)("fs_bshift %d dev_bshift = %d maxsymlinklen = %d\n",
                          mp->mnt_fs_bshift,mp->mnt_dev_bshift,mp->mnt_maxsymlinklen);
  
          bitmask_snprintf(mp->mnt_flag, __MNT_FLAG_BITS, sbuf, sizeof(sbuf));
          (*pr)("flag = %s\n", sbuf);
  
          bitmask_snprintf(mp->mnt_iflag, __IMNT_FLAG_BITS, sbuf, sizeof(sbuf));
          (*pr)("iflag = %s\n", sbuf);
  
          /* XXX use lockmgr_printinfo */
          if (mp->mnt_lock.lk_sharecount)
                  (*pr)(" lock type %s: SHARED (count %d)", mp->mnt_lock.lk_wmesg,
                      mp->mnt_lock.lk_sharecount);
          else if (mp->mnt_lock.lk_flags & LK_HAVE_EXCL) {
                  (*pr)(" lock type %s: EXCL (count %d) by ",
                      mp->mnt_lock.lk_wmesg, mp->mnt_lock.lk_exclusivecount);
                  if (mp->mnt_lock.lk_flags & LK_SPIN)
                          (*pr)("processor %lu", mp->mnt_lock.lk_cpu);
                  else
                          (*pr)("pid %d.%d", mp->mnt_lock.lk_lockholder,
                              mp->mnt_lock.lk_locklwp);
          } else
                  (*pr)(" not locked");
          if ((mp->mnt_lock.lk_flags & LK_SPIN) == 0 && mp->mnt_lock.lk_waitcount > 0)
                  (*pr)(" with %d pending", mp->mnt_lock.lk_waitcount);
  
          (*pr)("\n");
  
          if (mp->mnt_unmounter) {
                  (*pr)("unmounter pid = %d ",mp->mnt_unmounter->p_pid);
          }
          (*pr)("wcnt = %d, writeopcountupper = %d, writeopcountupper = %d\n",
                  mp->mnt_wcnt,mp->mnt_writeopcountupper,mp->mnt_writeopcountlower);
  
          (*pr)("statfs cache:\n");
          (*pr)("\ttype = %d\n",mp->mnt_stat.f_type);
          (*pr)("\toflags = 0x%04x\n",mp->mnt_stat.f_oflags);
          (*pr)("\tbsize = %d\n",mp->mnt_stat.f_bsize);
          (*pr)("\tiosize = %d\n",mp->mnt_stat.f_iosize);
          (*pr)("\tblocks = %d\n",mp->mnt_stat.f_blocks);
          (*pr)("\tbfree = %d\n",mp->mnt_stat.f_bfree);
          (*pr)("\tbavail = %d\n",mp->mnt_stat.f_bavail);
          (*pr)("\tfiles = %d\n",mp->mnt_stat.f_files);
          (*pr)("\tffree = %d\n",mp->mnt_stat.f_ffree);
          (*pr)("\tf_fsid = { 0x%"PRIx32", 0x%"PRIx32" }\n",
                          mp->mnt_stat.f_fsid.val[0],mp->mnt_stat.f_fsid.val[1]);
          (*pr)("\towner = %"PRIu32"\n",mp->mnt_stat.f_owner);
          bitmask_snprintf(mp->mnt_stat.f_flags, __MNT_FLAG_BITS, sbuf, sizeof(sbuf));
          (*pr)("\tflags = %s\n",sbuf);
          (*pr)("\tsyncwrites = %d\n",mp->mnt_stat.f_syncwrites);
          (*pr)("\tasyncwrites = %d\n",mp->mnt_stat.f_asyncwrites);
          (*pr)("\tfstypename = %s\n",mp->mnt_stat.f_fstypename);
          (*pr)("\tmntonname = %s\n",mp->mnt_stat.f_mntonname);
          (*pr)("\tmntfromname = %s\n",mp->mnt_stat.f_mntfromname);
  
          {
                  int cnt = 0;
                  struct vnode *vp;
                  (*pr)("locked vnodes =");
                  /* XXX would take mountlist lock, except ddb may not have context */
                  LIST_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes) {
                          if (VOP_ISLOCKED(vp)) {
                                  if ((++cnt % 6) == 0) {
                                          (*pr)(" %p,\n\t", vp);
                                  } else {
                                          (*pr)(" %p,", vp);
                                  }
                          }
                  }
                  (*pr)("\n");
          }
  
          if (full) {
                  int cnt = 0;
                  struct vnode *vp;
                  (*pr)("all vnodes =");
                  /* XXX would take mountlist lock, except ddb may not have context */
                  LIST_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes) {
                          if (!LIST_NEXT(vp, v_mntvnodes)) {
                                  (*pr)(" %p", vp);
                          } else if ((++cnt % 6) == 0) {
                                  (*pr)(" %p,\n\t", vp);
                          } else {
                                  (*pr)(" %p,", vp);
                          }
                  }
                  (*pr)("\n", vp);
          }
  }
  
  #endif