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[unix-history] / usr / src / sys / kern / vfs_subr.c

/*
* Copyright (c) 1989 The Regents of the University of California.
* All rights reserved.
*
* %sccs.include.redist.c%
*
*      @(#)vfs_subr.c  7.65 (Berkeley) %G%
*/

/*
* External virtual filesystem routines
*/

#include <sys/param.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/time.h>
#include <sys/vnode.h>
#include <sys/specdev.h>
#include <sys/namei.h>
#include <sys/ucred.h>
#include <sys/buf.h>
#include <sys/errno.h>
#include <sys/malloc.h>

/*
* Remove a mount point from the list of mounted filesystems.
* Unmount of the root is illegal.
*/
void
vfs_remove(mp)
       register struct mount *mp;
{

       if (mp == rootfs)
               panic("vfs_remove: unmounting root");
       mp->mnt_prev->mnt_next = mp->mnt_next;
       mp->mnt_next->mnt_prev = mp->mnt_prev;
       mp->mnt_vnodecovered->v_mountedhere = (struct mount *)0;
       vfs_unlock(mp);
}

/*
* Lock a filesystem.
* Used to prevent access to it while mounting and unmounting.
*/
vfs_lock(mp)
       register struct mount *mp;
{

       while(mp->mnt_flag & MNT_MLOCK) {
               mp->mnt_flag |= MNT_MWAIT;
               sleep((caddr_t)mp, PVFS);
       }
       mp->mnt_flag |= MNT_MLOCK;
       return (0);
}

/*
* Unlock a locked filesystem.
* Panic if filesystem is not locked.
*/
void
vfs_unlock(mp)
       register struct mount *mp;
{

       if ((mp->mnt_flag & MNT_MLOCK) == 0)
               panic("vfs_unlock: not locked");
       mp->mnt_flag &= ~MNT_MLOCK;
       if (mp->mnt_flag & MNT_MWAIT) {
               mp->mnt_flag &= ~MNT_MWAIT;
               wakeup((caddr_t)mp);
       }
}

/*
* Mark a mount point as busy.
* Used to synchronize access and to delay unmounting.
*/
vfs_busy(mp)
       register struct mount *mp;
{

       while(mp->mnt_flag & MNT_MPBUSY) {
               mp->mnt_flag |= MNT_MPWANT;
               sleep((caddr_t)&mp->mnt_flag, PVFS);
       }
       if (mp->mnt_flag & MNT_UNMOUNT)
               return (1);
       mp->mnt_flag |= MNT_MPBUSY;
       return (0);
}

/*
* Free a busy filesystem.
* Panic if filesystem is not busy.
*/
vfs_unbusy(mp)
       register struct mount *mp;
{

       if ((mp->mnt_flag & MNT_MPBUSY) == 0)
               panic("vfs_unbusy: not busy");
       mp->mnt_flag &= ~MNT_MPBUSY;
       if (mp->mnt_flag & MNT_MPWANT) {
               mp->mnt_flag &= ~MNT_MPWANT;
               wakeup((caddr_t)&mp->mnt_flag);
       }
}

/*
* Lookup a mount point by filesystem identifier.
*/
struct mount *
getvfs(fsid)
       fsid_t *fsid;
{
       register struct mount *mp;

       mp = rootfs;
       do {
               if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
                   mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
                       return (mp);
               }
               mp = mp->mnt_next;
       } while (mp != rootfs);
       return ((struct mount *)0);
}

/*
* Set vnode attributes to VNOVAL
*/
void vattr_null(vap)
       register struct vattr *vap;
{

       vap->va_type = VNON;
       vap->va_size = vap->va_bytes = VNOVAL;
#ifdef _NOQUAD
       vap->va_size_rsv = vap->va_bytes_rsv = VNOVAL;
#endif
       vap->va_mode = vap->va_nlink = vap->va_uid = vap->va_gid =
               vap->va_fsid = vap->va_fileid =
               vap->va_blocksize = vap->va_rdev =
               vap->va_atime.tv_sec = vap->va_atime.tv_usec =
               vap->va_mtime.tv_sec = vap->va_mtime.tv_usec =
               vap->va_ctime.tv_sec = vap->va_ctime.tv_usec =
               vap->va_flags = vap->va_gen = VNOVAL;
}

/*
* Routines having to do with the management of the vnode table.
*/
struct vnode *vfreeh, **vfreet;
extern struct vnodeops dead_vnodeops, spec_vnodeops;
extern void vclean();
long numvnodes;
struct vattr va_null;

/*
* Initialize the vnode structures and initialize each file system type.
*/
vfsinit()
{
       struct vfsops **vfsp;

       /*
        * Initialize the vnode name cache
        */
       nchinit();
       /*
        * Initialize each file system type.
        */
       vattr_null(&va_null);
       for (vfsp = &vfssw[0]; vfsp <= &vfssw[MOUNT_MAXTYPE]; vfsp++) {
               if (*vfsp == NULL)
                       continue;
               (*(*vfsp)->vfs_init)();
       }
}

/*
* Return the next vnode from the free list.
*/
getnewvnode(tag, mp, vops, vpp)
       enum vtagtype tag;
       struct mount *mp;
       struct vnodeops *vops;
       struct vnode **vpp;
{
       register struct vnode *vp, *vq;

       if (numvnodes < desiredvnodes) {
               vp = (struct vnode *)malloc((u_long)sizeof *vp,
                   M_VNODE, M_WAITOK);
               bzero((char *)vp, sizeof *vp);
               numvnodes++;
       } else {
               if ((vp = vfreeh) == NULL) {
                       tablefull("vnode");
                       *vpp = 0;
                       return (ENFILE);
               }
               if (vp->v_usecount)
                       panic("free vnode isn't");
               if (vq = vp->v_freef)
                       vq->v_freeb = &vfreeh;
               else
                       vfreet = &vfreeh;
               vfreeh = vq;
               vp->v_freef = NULL;
               vp->v_freeb = NULL;
               vp->v_lease = NULL;
               if (vp->v_type != VBAD)
                       vgone(vp);
               if (vp->v_data)
                       panic("cleaned vnode isn't");
               vp->v_flag = 0;
               vp->v_lastr = 0;
               vp->v_socket = 0;
       }
       vp->v_type = VNON;
       cache_purge(vp);
       vp->v_tag = tag;
       vp->v_op = vops;
       insmntque(vp, mp);
       VREF(vp);
       *vpp = vp;
       return (0);
}

/*
* Move a vnode from one mount queue to another.
*/
insmntque(vp, mp)
       register struct vnode *vp;
       register struct mount *mp;
{
       register struct vnode *vq;

       /*
        * Delete from old mount point vnode list, if on one.
        */
       if (vp->v_mountb) {
               if (vq = vp->v_mountf)
                       vq->v_mountb = vp->v_mountb;
               *vp->v_mountb = vq;
       }
       /*
        * Insert into list of vnodes for the new mount point, if available.
        */
       vp->v_mount = mp;
       if (mp == NULL) {
               vp->v_mountf = NULL;
               vp->v_mountb = NULL;
               return;
       }
       if (vq = mp->mnt_mounth)
               vq->v_mountb = &vp->v_mountf;
       vp->v_mountf = vq;
       vp->v_mountb = &mp->mnt_mounth;
       mp->mnt_mounth = vp;
}

/*
* Make sure all write-behind blocks associated
* with mount point are flushed out (from sync).
*/
mntflushbuf(mountp, flags)
       struct mount *mountp;
       int flags;
{
       register struct vnode *vp;

       if ((mountp->mnt_flag & MNT_MPBUSY) == 0)
               panic("mntflushbuf: not busy");
loop:
       for (vp = mountp->mnt_mounth; vp; vp = vp->v_mountf) {
               if (VOP_ISLOCKED(vp))
                       continue;
               if (vget(vp))
                       goto loop;
               vflushbuf(vp, flags);
               vput(vp);
               if (vp->v_mount != mountp)
                       goto loop;
       }
}

/*
* Flush all dirty buffers associated with a vnode.
*/
vflushbuf(vp, flags)
       register struct vnode *vp;
       int flags;
{
       register struct buf *bp;
       struct buf *nbp;
       int s;

loop:
       s = splbio();
       for (bp = vp->v_dirtyblkhd; bp; bp = nbp) {
               nbp = bp->b_blockf;
               if ((bp->b_flags & B_BUSY))
                       continue;
               if ((bp->b_flags & B_DELWRI) == 0)
                       panic("vflushbuf: not dirty");
               bremfree(bp);
               bp->b_flags |= B_BUSY;
               splx(s);
               /*
                * Wait for I/O associated with indirect blocks to complete,
                * since there is no way to quickly wait for them below.
                * NB: This is really specific to ufs, but is done here
                * as it is easier and quicker.
                */
               if (bp->b_vp == vp || (flags & B_SYNC) == 0)
                       (void) bawrite(bp);
               else
                       (void) bwrite(bp);
               goto loop;
       }
       splx(s);
       if ((flags & B_SYNC) == 0)
               return;
       s = splbio();
       while (vp->v_numoutput) {
               vp->v_flag |= VBWAIT;
               sleep((caddr_t)&vp->v_numoutput, PRIBIO + 1);
       }
       splx(s);
       if (vp->v_dirtyblkhd) {
               vprint("vflushbuf: dirty", vp);
               goto loop;
       }
}

/*
* Update outstanding I/O count and do wakeup if requested.
*/
vwakeup(bp)
       register struct buf *bp;
{
       register struct vnode *vp;

       bp->b_dirtyoff = bp->b_dirtyend = 0;
       if (vp = bp->b_vp) {
               vp->v_numoutput--;
               if ((vp->v_flag & VBWAIT) && vp->v_numoutput <= 0) {
                       if (vp->v_numoutput < 0)
                               panic("vwakeup: neg numoutput");
                       vp->v_flag &= ~VBWAIT;
                       wakeup((caddr_t)&vp->v_numoutput);
               }
       }
}

/*
* Invalidate in core blocks belonging to closed or umounted filesystem
*
* Go through the list of vnodes associated with the file system;
* for each vnode invalidate any buffers that it holds. Normally
* this routine is preceeded by a bflush call, so that on a quiescent
* filesystem there will be no dirty buffers when we are done. Binval
* returns the count of dirty buffers when it is finished.
*/
mntinvalbuf(mountp)
       struct mount *mountp;
{
       register struct vnode *vp;
       int dirty = 0;

       if ((mountp->mnt_flag & MNT_MPBUSY) == 0)
               panic("mntinvalbuf: not busy");
loop:
       for (vp = mountp->mnt_mounth; vp; vp = vp->v_mountf) {
               if (vget(vp))
                       goto loop;
               dirty += vinvalbuf(vp, 1);
               vput(vp);
               if (vp->v_mount != mountp)
                       goto loop;
       }
       return (dirty);
}

/*
* Flush out and invalidate all buffers associated with a vnode.
* Called with the underlying object locked.
*/
vinvalbuf(vp, save)
       register struct vnode *vp;
       int save;
{
       register struct buf *bp;
       struct buf *nbp, *blist;
       int s, dirty = 0;

       for (;;) {
               if (blist = vp->v_dirtyblkhd)
                       /* void */;
               else if (blist = vp->v_cleanblkhd)
                       /* void */;
               else
                       break;
               for (bp = blist; bp; bp = nbp) {
                       nbp = bp->b_blockf;
                       s = splbio();
                       if (bp->b_flags & B_BUSY) {
                               bp->b_flags |= B_WANTED;
                               sleep((caddr_t)bp, PRIBIO + 1);
                               splx(s);
                               break;
                       }
                       bremfree(bp);
                       bp->b_flags |= B_BUSY;
                       splx(s);
                       if (save && (bp->b_flags & B_DELWRI)) {
                               dirty++;
                               (void) VOP_BWRITE(bp);
                               break;
                       }
                       if (bp->b_vp != vp)
                               reassignbuf(bp, bp->b_vp);
                       else
                               bp->b_flags |= B_INVAL;
                       brelse(bp);
               }
       }
       if (vp->v_dirtyblkhd || vp->v_cleanblkhd)
               panic("vinvalbuf: flush failed");
       return (dirty);
}

/*
* Associate a buffer with a vnode.
*/
bgetvp(vp, bp)
       register struct vnode *vp;
       register struct buf *bp;
{
       register struct vnode *vq;
       register struct buf *bq;

       if (bp->b_vp)
               panic("bgetvp: not free");
       VHOLD(vp);
       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.
        */
       if (bq = vp->v_cleanblkhd)
               bq->b_blockb = &bp->b_blockf;
       bp->b_blockf = bq;
       bp->b_blockb = &vp->v_cleanblkhd;
       vp->v_cleanblkhd = bp;
}

/*
* Disassociate a buffer from a vnode.
*/
brelvp(bp)
       register struct buf *bp;
{
       struct buf *bq;
       struct vnode *vp;

       if (bp->b_vp == (struct vnode *) 0)
               panic("brelvp: NULL");
       /*
        * Delete from old vnode list, if on one.
        */
       if (bp->b_blockb) {
               if (bq = bp->b_blockf)
                       bq->b_blockb = bp->b_blockb;
               *bp->b_blockb = bq;
               bp->b_blockf = NULL;
               bp->b_blockb = NULL;
       }
       vp = bp->b_vp;
       bp->b_vp = (struct vnode *) 0;
       HOLDRELE(vp);
}

/*
* Reassign a buffer from one vnode to another.
* Used to assign file specific control information
* (indirect blocks) to the vnode to which they belong.
*/
reassignbuf(bp, newvp)
       register struct buf *bp;
       register struct vnode *newvp;
{
       register struct buf *bq, **listheadp;

       if (newvp == NULL)
               panic("reassignbuf: NULL");
       /*
        * Delete from old vnode list, if on one.
        */
       if (bp->b_blockb) {
               if (bq = bp->b_blockf)
                       bq->b_blockb = bp->b_blockb;
               *bp->b_blockb = bq;
       }
       /*
        * If dirty, put on list of dirty buffers;
        * otherwise insert onto list of clean buffers.
        */
       if (bp->b_flags & B_DELWRI)
               listheadp = &newvp->v_dirtyblkhd;
       else
               listheadp = &newvp->v_cleanblkhd;
       if (bq = *listheadp)
               bq->b_blockb = &bp->b_blockf;
       bp->b_blockf = bq;
       bp->b_blockb = listheadp;
       *listheadp = bp;
}

/*
* Create a vnode for a block device.
* Used for root filesystem, argdev, and swap areas.
* Also used for memory file system special devices.
*/
bdevvp(dev, vpp)
       dev_t dev;
       struct vnode **vpp;
{
       register struct vnode *vp;
       struct vnode *nvp;
       int error;

       if (dev == NODEV)
               return (0);
       error = getnewvnode(VT_NON, (struct mount *)0, &spec_vnodeops, &nvp);
       if (error) {
               *vpp = 0;
               return (error);
       }
       vp = nvp;
       vp->v_type = VBLK;
       if (nvp = checkalias(vp, dev, (struct mount *)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)
       register struct vnode *nvp;
       dev_t nvp_rdev;
       struct mount *mp;
{
       register struct vnode *vp;
       struct vnode **vpp;

       if (nvp->v_type != VBLK && nvp->v_type != VCHR)
               return (NULLVP);

       vpp = &speclisth[SPECHASH(nvp_rdev)];
loop:
       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.
                */
               if (vp->v_usecount == 0) {
                       vgone(vp);
                       goto loop;
               }
               if (vget(vp))
                       goto loop;
               break;
       }
       if (vp == NULL || vp->v_tag != VT_NON) {
               MALLOC(nvp->v_specinfo, struct specinfo *,
                       sizeof(struct specinfo), M_VNODE, M_WAITOK);
               nvp->v_rdev = nvp_rdev;
               nvp->v_hashchain = vpp;
               nvp->v_specnext = *vpp;
               nvp->v_specflags = 0;
               *vpp = nvp;
               if (vp != NULL) {
                       nvp->v_flag |= VALIASED;
                       vp->v_flag |= VALIASED;
                       vput(vp);
               }
               return (NULLVP);
       }
       VOP_UNLOCK(vp);
       vclean(vp, 0);
       vp->v_op = nvp->v_op;
       vp->v_tag = nvp->v_tag;
       nvp->v_type = VNON;
       insmntque(vp, mp);
       return (vp);
}

/*
* Grab a particular vnode from the free list, increment its
* reference count and lock it. The vnode lock bit is set the
* vnode is being eliminated in vgone. 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).
*/
vget(vp)
       register struct vnode *vp;
{
       register struct vnode *vq;

       if (vp->v_flag & VXLOCK) {
               vp->v_flag |= VXWANT;
               sleep((caddr_t)vp, PINOD);
               return (1);
       }
       if (vp->v_usecount == 0) {
               if (vq = vp->v_freef)
                       vq->v_freeb = vp->v_freeb;
               else
                       vfreet = vp->v_freeb;
               *vp->v_freeb = vq;
               vp->v_freef = NULL;
               vp->v_freeb = NULL;
       }
       VREF(vp);
       VOP_LOCK(vp);
       return (0);
}

/*
* Vnode reference, just increment the count
*/
void vref(vp)
       struct vnode *vp;
{

       vp->v_usecount++;
}

/*
* vput(), just unlock and vrele()
*/
void vput(vp)
       register struct vnode *vp;
{
       VOP_UNLOCK(vp);
       vrele(vp);
}

/*
* Vnode release.
* If count drops to zero, call inactive routine and return to freelist.
*/
void vrele(vp)
       register struct vnode *vp;
{
       struct proc *p = curproc;               /* XXX */

#ifdef DIAGNOSTIC
       if (vp == NULL)
               panic("vrele: null vp");
#endif
       vp->v_usecount--;
       if (vp->v_usecount > 0)
               return;
#ifdef DIAGNOSTIC
       if (vp->v_usecount != 0 || vp->v_writecount != 0) {
               vprint("vrele: bad ref count", vp);
               panic("vrele: ref cnt");
       }
#endif
       if (vfreeh == NULLVP) {
               /*
                * insert into empty list
                */
               vfreeh = vp;
               vp->v_freeb = &vfreeh;
       } else {
               /*
                * insert at tail of list
                */
               *vfreet = vp;
               vp->v_freeb = vfreet;
       }
       vp->v_freef = NULL;
       vfreet = &vp->v_freef;
       VOP_INACTIVE(vp, p);
}

/*
* Page or buffer structure gets a reference.
*/
vhold(vp)
       register struct vnode *vp;
{

       vp->v_holdcnt++;
}

/*
* Page or buffer structure frees a reference.
*/
holdrele(vp)
       register struct vnode *vp;
{

       if (vp->v_holdcnt <= 0)
               panic("holdrele: holdcnt");
       vp->v_holdcnt--;
}

/*
* Remove any vnodes in the vnode table belonging to mount point mp.
*
* If MNT_NOFORCE is 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 MNT_FORCE is specified, detach any active vnodes
* that are found.
*/
int busyprt = 0;        /* patch to print out busy vnodes */

vflush(mp, skipvp, flags)
       struct mount *mp;
       struct vnode *skipvp;
       int flags;
{
       register struct vnode *vp, *nvp;
       int busy = 0;

       if ((mp->mnt_flag & MNT_MPBUSY) == 0)
               panic("vflush: not busy");
loop:
       for (vp = mp->mnt_mounth; vp; vp = nvp) {
               if (vp->v_mount != mp)
                       goto loop;
               nvp = vp->v_mountf;
               /*
                * Skip over a selected vnode.
                */
               if (vp == skipvp)
                       continue;
               /*
                * Skip over a vnodes marked VSYSTEM.
                */
               if ((flags & SKIPSYSTEM) && (vp->v_flag & VSYSTEM))
                       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) {
                       vgone(vp);
                       continue;
               }
               /*
                * For block or character devices, revert to an
                * anonymous device. For all other files, just kill them.
                */
               if (flags & FORCECLOSE) {
                       if (vp->v_type != VBLK && vp->v_type != VCHR) {
                               vgone(vp);
                       } else {
                               vclean(vp, 0);
                               vp->v_op = &spec_vnodeops;
                               insmntque(vp, (struct mount *)0);
                       }
                       continue;
               }
               if (busyprt)
                       vprint("vflush: busy vnode", vp);
               busy++;
       }
       if (busy)
               return (EBUSY);
       return (0);
}

/*
* Disassociate the underlying file system from a vnode.
*/
void vclean(vp, flags)
       register struct vnode *vp;
       int flags;
{
       struct vnodeops *origops;
       int active;
       struct proc *p = curproc;       /* XXX */

       /*
        * 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)
               VREF(vp);
       /*
        * Prevent the vnode from being recycled or
        * brought into use while we clean it out.
        */
       if (vp->v_flag & VXLOCK)
               panic("vclean: deadlock");
       vp->v_flag |= VXLOCK;
       /*
        * 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 buffer list is being cleaned out.
        */
       VOP_LOCK(vp);
       if (flags & DOCLOSE)
               vinvalbuf(vp, 1);
       /*
        * Prevent any further operations on the vnode from
        * being passed through to the old file system.
        */
       origops = vp->v_op;
       vp->v_op = &dead_vnodeops;
       vp->v_tag = VT_NON;
       /*
        * If purging an active vnode, it must be unlocked, closed,
        * and deactivated before being reclaimed.
        */
       (*(origops->vop_unlock))(vp);
       if (active) {
               if (flags & DOCLOSE)
                       (*(origops->vop_close))(vp, IO_NDELAY, NOCRED, p);
               (*(origops->vop_inactive))(vp, p);
       }
       /*
        * Reclaim the vnode.
        */
       if ((*(origops->vop_reclaim))(vp))
               panic("vclean: cannot reclaim");
       if (active)
               vrele(vp);
       /*
        * Done with purge, notify sleepers in vget of the grim news.
        */
       vp->v_flag &= ~VXLOCK;
       if (vp->v_flag & VXWANT) {
               vp->v_flag &= ~VXWANT;
               wakeup((caddr_t)vp);
       }
}

/*
* Eliminate all activity associated with  the requested vnode
* and with all vnodes aliased to the requested vnode.
*/
void vgoneall(vp)
       register struct vnode *vp;
{
       register struct vnode *vq;

       if (vp->v_flag & VALIASED) {
               /*
                * 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;
                       sleep((caddr_t)vp, PINOD);
                       return;
               }
               /*
                * Ensure that vp will not be vgone'd while we
                * are eliminating its aliases.
                */
               vp->v_flag |= VXLOCK;
               while (vp->v_flag & VALIASED) {
                       for (vq = *vp->v_hashchain; vq; vq = vq->v_specnext) {
                               if (vq->v_rdev != vp->v_rdev ||
                                   vq->v_type != vp->v_type || vp == vq)
                                       continue;
                               vgone(vq);
                               break;
                       }
               }
               /*
                * Remove the lock so that vgone below will
                * really eliminate the vnode after which time
                * vgone will awaken any sleepers.
                */
               vp->v_flag &= ~VXLOCK;
       }
       vgone(vp);
}

/*
* Eliminate all activity associated with a vnode
* in preparation for reuse.
*/
void vgone(vp)
       register struct vnode *vp;
{
       register struct vnode *vq;
       struct vnode *vx;
       long count;

       /*
        * 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;
               sleep((caddr_t)vp, PINOD);
               return;
       }
       /*
        * Clean out the filesystem specific data.
        */
       vclean(vp, DOCLOSE);
       /*
        * Delete from old mount point vnode list, if on one.
        */
       if (vp->v_mountb) {
               if (vq = vp->v_mountf)
                       vq->v_mountb = vp->v_mountb;
               *vp->v_mountb = vq;
               vp->v_mountf = NULL;
               vp->v_mountb = NULL;
       }
       /*
        * If special device, remove it from special device alias list.
        */
       if (vp->v_type == VBLK || vp->v_type == VCHR) {
               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) {
                       count = 0;
                       for (vq = *vp->v_hashchain; vq; vq = vq->v_specnext) {
                               if (vq->v_rdev != vp->v_rdev ||
                                   vq->v_type != vp->v_type)
                                       continue;
                               count++;
                               vx = vq;
                       }
                       if (count == 0)
                               panic("missing alias");
                       if (count == 1)
                               vx->v_flag &= ~VALIASED;
                       vp->v_flag &= ~VALIASED;
               }
               FREE(vp->v_specinfo, M_VNODE);
               vp->v_specinfo = NULL;
       }
       /*
        * If it is on the freelist, move it to the head of the list.
        */
       if (vp->v_freeb) {
               if (vq = vp->v_freef)
                       vq->v_freeb = vp->v_freeb;
               else
                       vfreet = vp->v_freeb;
               *vp->v_freeb = vq;
               vp->v_freef = vfreeh;
               vp->v_freeb = &vfreeh;
               vfreeh->v_freeb = &vp->v_freef;
               vfreeh = vp;
       }
       vp->v_type = VBAD;
}

/*
* Lookup a vnode by device number.
*/
vfinddev(dev, type, vpp)
       dev_t dev;
       enum vtype type;
       struct vnode **vpp;
{
       register struct vnode *vp;

       for (vp = speclisth[SPECHASH(dev)]; vp; vp = vp->v_specnext) {
               if (dev != vp->v_rdev || type != vp->v_type)
                       continue;
               *vpp = vp;
               return (0);
       }
       return (1);
}

/*
* Calculate the total number of references to a special device.
*/
vcount(vp)
       register struct vnode *vp;
{
       register struct vnode *vq;
       int count;

       if ((vp->v_flag & VALIASED) == 0)
               return (vp->v_usecount);
loop:
       for (count = 0, vq = *vp->v_hashchain; vq; vq = 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) {
                       vgone(vq);
                       goto loop;
               }
               count += vq->v_usecount;
       }
       return (count);
}

/*
* Print out a description of a vnode.
*/
static char *typename[] =
  { "VNON", "VREG", "VDIR", "VBLK", "VCHR", "VLNK", "VSOCK", "VFIFO", "VBAD" };

vprint(label, vp)
       char *label;
       register struct vnode *vp;
{
       char buf[64];

       if (label != NULL)
               printf("%s: ", label);
       printf("type %s, usecount %d, writecount %d, refcount %d,",
               typename[vp->v_type], vp->v_usecount, vp->v_writecount,
               vp->v_holdcnt);
       buf[0] = '\0';
       if (vp->v_flag & VROOT)
               strcat(buf, "|VROOT");
       if (vp->v_flag & VTEXT)
               strcat(buf, "|VTEXT");
       if (vp->v_flag & VSYSTEM)
               strcat(buf, "|VSYSTEM");
       if (vp->v_flag & VXLOCK)
               strcat(buf, "|VXLOCK");
       if (vp->v_flag & VXWANT)
               strcat(buf, "|VXWANT");
       if (vp->v_flag & VBWAIT)
               strcat(buf, "|VBWAIT");
       if (vp->v_flag & VALIASED)
               strcat(buf, "|VALIASED");
       if (buf[0] != '\0')
               printf(" flags (%s)", &buf[1]);
       printf("\n\t");
       VOP_PRINT(vp);
}

#ifdef DEBUG
/*
* List all of the locked vnodes in the system.
* Called when debugging the kernel.
*/
printlockedvnodes()
{
       register struct mount *mp;
       register struct vnode *vp;

       printf("Locked vnodes\n");
       mp = rootfs;
       do {
               for (vp = mp->mnt_mounth; vp; vp = vp->v_mountf)
                       if (VOP_ISLOCKED(vp))
                               vprint((char *)0, vp);
               mp = mp->mnt_next;
       } while (mp != rootfs);
}
#endif

int kinfo_vdebug = 1;
int kinfo_vgetfailed;
#define KINFO_VNODESLOP 10
/*
* Dump vnode list (via kinfo).
* Copyout address of vnode followed by vnode.
*/
/* ARGSUSED */
kinfo_vnode(op, where, acopysize, arg, aneeded)
       int op;
       char *where;
       int *acopysize, arg, *aneeded;
{
       register struct mount *mp = rootfs;
       struct mount *omp;
       struct vnode *vp;
       register char *bp = where, *savebp;
       char *ewhere = where + *acopysize;
       int error;

#define VPTRSZ  sizeof (struct vnode *)
#define VNODESZ sizeof (struct vnode)
       if (where == NULL) {
               *aneeded = (numvnodes + KINFO_VNODESLOP) * (VPTRSZ + VNODESZ);
               return (0);
       }
               
       do {
               if (vfs_busy(mp)) {
                       mp = mp->mnt_next;
                       continue;
               }
               savebp = bp;
again:
               for (vp = mp->mnt_mounth; vp; vp = vp->v_mountf) {
                       /*
                        * Check that the vp is still associated with
                        * this filesystem.  RACE: could have been
                        * recycled onto the same filesystem.
                        */
                       if (vp->v_mount != mp) {
                               if (kinfo_vdebug)
                                       printf("kinfo: vp changed\n");
                               bp = savebp;
                               goto again;
                       }
                       if ((bp + VPTRSZ + VNODESZ <= ewhere) && 
                           ((error = copyout((caddr_t)&vp, bp, VPTRSZ)) ||
                            (error = copyout((caddr_t)vp, bp + VPTRSZ, 
                             VNODESZ))))
                               return (error);
                       bp += VPTRSZ + VNODESZ;
               }
               omp = mp;
               mp = mp->mnt_next;
               vfs_unbusy(omp);
       } while (mp != rootfs);

       *aneeded = bp - where;
       if (bp > ewhere)
               *acopysize = ewhere - where;
       else
               *acopysize = bp - where;
       return (0);
}