/*      $OpenBSD: vfs_subr.c,v 1.333 2025/11/08 17:23:22 mpi Exp $      */
/*      $NetBSD: vfs_subr.c,v 1.53 1996/04/22 01:39:13 christos Exp $   */

/*
 * 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/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/sysctl.h>
#include <sys/mount.h>
#include <sys/fcntl.h>
#include <sys/conf.h>
#include <sys/vnode.h>
#include <sys/lock.h>
#include <sys/lockf.h>
#include <sys/stat.h>
#include <sys/acct.h>
#include <sys/namei.h>
#include <sys/ucred.h>
#include <sys/buf.h>
#include <sys/errno.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/syscallargs.h>
#include <sys/pool.h>
#include <sys/tree.h>
#include <sys/specdev.h>
#include <sys/atomic.h>

#include <netinet/in.h>

#include <uvm/uvm_vnode.h>

#include "softraid.h"

/*
 * Locks used to protect data:
 *      a       atomic
 */

void sr_quiesce(void);

enum vtype iftovt_tab[16] = {
        VNON, VFIFO, VCHR, VNON, VDIR, VNON, VBLK, VNON,
        VREG, VNON, VLNK, VNON, VSOCK, VNON, VNON, VBAD,
};

int     vttoif_tab[9] = {
        0, S_IFREG, S_IFDIR, S_IFBLK, S_IFCHR, S_IFLNK,
        S_IFSOCK, S_IFIFO, S_IFMT,
};

int prtactive = 0;      /* 1 => print out reclaim of active vnodes */

/*
 * 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);                                      \
        LIST_NEXT(bp, b_vnbufs) = NOLIST;                               \
}

TAILQ_HEAD(freelst, vnode);
struct freelst vnode_hold_list; /* list of vnodes referencing buffers */
struct freelst vnode_free_list; /* vnode free list */

struct mntlist mountlist;       /* mounted filesystem list */

void    vclean(struct vnode *, int, struct proc *);

void insmntque(struct vnode *, struct mount *);
int getdevvp(dev_t, struct vnode **, enum vtype);

int vfs_hang_addrlist(struct mount *, struct netexport *,
                                  struct export_args *);
int vfs_free_netcred(struct radix_node *, void *, u_int);
void vfs_free_addrlist(struct netexport *);
void vputonfreelist(struct vnode *);

int vflush_vnode(struct vnode *, void *);
int maxvnodes;

struct mutex vnode_mtx = MUTEX_INITIALIZER(IPL_BIO);

void vfs_unmountall(void);

#ifdef DEBUG
void printlockedvnodes(void);
#endif

struct pool vnode_pool;

static inline int rb_buf_compare(const struct buf *b1, const struct buf *b2);
RBT_GENERATE(buf_rb_bufs, buf, b_rbbufs, rb_buf_compare);

static inline int
rb_buf_compare(const struct buf *b1, const struct buf *b2)
{
        if (b1->b_lblkno < b2->b_lblkno)
                return(-1);
        if (b1->b_lblkno > b2->b_lblkno)
                return(1);
        return(0);
}

/*
 * Initialize the vnode management data structures.
 */
void
vntblinit(void)
{
        /* buffer cache may need a vnode for each buffer */
        maxvnodes = 2 * initialvnodes;
        pool_init(&vnode_pool, sizeof(struct vnode), 0, IPL_NONE,
            PR_WAITOK, "vnodes", NULL);
        TAILQ_INIT(&vnode_hold_list);
        TAILQ_INIT(&vnode_free_list);
        TAILQ_INIT(&mountlist);
        /*
         * Initialize the filesystem syncer.
         */
        vn_initialize_syncerd();

#ifdef NFSSERVER
        rn_init(sizeof(struct sockaddr_in));
#endif /* NFSSERVER */
}

/*
 * Allocate a mount point.
 *
 * The returned mount point is marked as busy.
 */
struct mount *
vfs_mount_alloc(struct vnode *vp, struct vfsconf *vfsp)
{
        struct mount *mp;

        mp = malloc(sizeof(*mp), M_MOUNT, M_WAITOK|M_ZERO);
        refcnt_init(&mp->mnt_refs);
        rw_init_flags(&mp->mnt_lock, "vfslock", RWL_IS_VNODE);
        (void)vfs_busy(mp, VB_READ|VB_NOWAIT);

        TAILQ_INIT(&mp->mnt_vnodelist);
        mp->mnt_vnodecovered = vp;

        atomic_inc_int(&vfsp->vfc_refcount);
        mp->mnt_vfc = vfsp;
        mp->mnt_op = vfsp->vfc_vfsops;
        mp->mnt_flag = vfsp->vfc_flags;
        strncpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN);

        return (mp);
}

struct mount *
vfs_mount_take(struct mount *mp)
{
        refcnt_take(&mp->mnt_refs);
        return (mp);
}

static void
vfs_mount_rele(struct mount *mp)
{
        if (refcnt_rele(&mp->mnt_refs))
                free(mp, M_MOUNT, sizeof(*mp));
}

/*
 * Release a mount point.
 */
void
vfs_mount_free(struct mount *mp)
{
        SET(mp->mnt_flag, MNT_UNMOUNT);
        atomic_dec_int(&mp->mnt_vfc->vfc_refcount);
        vfs_mount_rele(mp);
}

/*
 * Mark a mount point as busy. Used to synchronize access and to delay
 * unmounting.
 *
 * Default behaviour is to attempt getting a READ lock and in case of an
 * ongoing unmount, to wait for it to finish and then return failure.
 */
int
vfs_busy(struct mount *mp, int flags)
{
        int rwflags = ISSET(flags, VB_WRITE) ? RW_WRITE : RW_READ;
        int error = 0;

        if (!ISSET(flags, VB_WAIT))
                rwflags |= RW_NOSLEEP;

#ifdef WITNESS
        if (ISSET(flags, VB_DUPOK))
                rwflags |= RW_DUPOK;
#endif

        vfs_mount_take(mp);
        if (rw_enter(&mp->mnt_lock, rwflags) != 0)
                error = EBUSY;
        else if (ISSET(mp->mnt_flag, MNT_UNMOUNT)) {
                rw_exit(&mp->mnt_lock);
                error = EBUSY;
        }
        vfs_mount_rele(mp);

        return (error);
}

/*
 * Free a busy file system
 */
void
vfs_unbusy(struct mount *mp)
{
        rw_exit(&mp->mnt_lock);
}

int
vfs_isbusy(struct mount *mp)
{
        return (rw_status(&mp->mnt_lock) != 0);
}

/*
 * 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(char *fstypename, char *devname, struct mount **mpp)
{
        struct vfsconf *vfsp;
        struct mount *mp;

        vfsp = vfs_byname(fstypename);
        if (vfsp == NULL)
                return (ENODEV);
        mp = vfs_mount_alloc(NULL, vfsp);
        mp->mnt_flag |= MNT_RDONLY;
        mp->mnt_stat.f_mntonname[0] = '/';
        strlcpy(mp->mnt_stat.f_mntfromname, devname, MNAMELEN);
        strlcpy(mp->mnt_stat.f_mntfromspec, devname, MNAMELEN);
        *mpp = mp;
        return (0);
 }

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

        TAILQ_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]) {
                        return (mp);
                }
        }

        return (NULL);
}


/*
 * Get a new unique fsid
 */
void
vfs_getnewfsid(struct mount *mp)
{
        static u_short xxxfs_mntid;

        fsid_t tfsid;
        int mtype;

        mtype = mp->mnt_vfc->vfc_typenum;
        mp->mnt_stat.f_fsid.val[0] = makedev(nblkdev + mtype, 0);
        mp->mnt_stat.f_fsid.val[1] = mtype;
        if (xxxfs_mntid == 0)
                ++xxxfs_mntid;
        tfsid.val[0] = makedev(nblkdev + mtype, xxxfs_mntid);
        tfsid.val[1] = mtype;
        if (!TAILQ_EMPTY(&mountlist)) {
                while (vfs_getvfs(&tfsid)) {
                        tfsid.val[0]++;
                        xxxfs_mntid++;
                }
        }
        mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
}

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

        vap->va_type = VNON;
        /*
         * Don't get fancy: u_quad_t = u_int = VNOVAL leaves the u_quad_t
         * with 2^31-1 instead of 2^64-1.  Just write'm out and let
         * the compiler do its job.
         */
        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 = VNOVAL;
        vap->va_atime.tv_nsec = VNOVAL;
        vap->va_mtime.tv_sec = VNOVAL;
        vap->va_mtime.tv_nsec = VNOVAL;
        vap->va_ctime.tv_sec = VNOVAL;
        vap->va_ctime.tv_nsec = VNOVAL;
        vap->va_gen = VNOVAL;
        vap->va_flags = VNOVAL;
        vap->va_rdev = VNOVAL;
        vap->va_bytes = VNOVAL;
        vap->va_filerev = VNOVAL;
        vap->va_vaflags = 0;
}

/*
 * Routines having to do with the management of the vnode table.
 */
long numvnodes;

/*
 * Return the next vnode from the free list.
 */
int
getnewvnode(enum vtagtype tag, struct mount *mp, const struct vops *vops,
    struct vnode **vpp)
{
        struct proc *p = curproc;
        struct freelst *listhd;
        static int toggle;
        struct vnode *vp;
        int s;

        /*
         * allow maxvnodes to increase if the buffer cache itself
         * is big enough to justify it. (we don't shrink it ever)
         */
        maxvnodes = maxvnodes < bcstats.numbufs ? bcstats.numbufs
            : maxvnodes;

        /*
         * 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.
         */
        toggle ^= 1;
        if (numvnodes / 2 > maxvnodes)
                toggle = 0;

        s = splbio();
        if ((numvnodes < maxvnodes) ||
            ((TAILQ_FIRST(listhd = &vnode_free_list) == NULL) &&
            ((TAILQ_FIRST(listhd = &vnode_hold_list) == NULL) || toggle))) {
                splx(s);
                vp = pool_get(&vnode_pool, PR_WAITOK | PR_ZERO);
                RBT_INIT(buf_rb_bufs, &vp->v_bufs_tree);
                cache_tree_init(&vp->v_nc_tree);
                TAILQ_INIT(&vp->v_cache_dst);
                numvnodes++;
        } else {
                TAILQ_FOREACH(vp, listhd, v_freelist) {
                        if (VOP_ISLOCKED(vp) == 0)
                                break;
                }
                /*
                 * 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 == NULL) {
                        splx(s);
                        tablefull("vnode");
                        *vpp = NULL;
                        return (ENFILE);
                }

#ifdef DIAGNOSTIC
                if (vp->v_usecount) {
                        vprint("free vnode", vp);
                        panic("free vnode isn't");
                }
#endif

                TAILQ_REMOVE(listhd, vp, v_freelist);
                vp->v_bioflag &= ~VBIOONFREELIST;
                splx(s);

                if (vp->v_type != VBAD)
                        vgonel(vp, p);
#ifdef DIAGNOSTIC
                if (vp->v_data) {
                        vprint("cleaned vnode", vp);
                        panic("cleaned vnode isn't");
                }
                s = splbio();
                if (vp->v_numoutput)
                        panic("Clean vnode has pending I/O's");
                splx(s);
#endif
                vp->v_flag = 0;
                vp->v_socket = NULL;
        }
        cache_purge(vp);
        vp->v_type = VNON;
        vp->v_tag = tag;
        vp->v_op = vops;
        insmntque(vp, mp);
        *vpp = vp;
        vp->v_usecount = 1;
        vp->v_data = NULL;
        return (0);
}

/*
 * Move a vnode from one mount queue to another.
 */
void
insmntque(struct vnode *vp, struct mount *mp)
{
        /*
         * Delete from old mount point vnode list, if on one.
         */
        if (vp->v_mount != NULL)
                TAILQ_REMOVE(&vp->v_mount->mnt_vnodelist, vp, v_mntvnodes);
        /*
         * Insert into list of vnodes for the new mount point, if available.
         */
        if ((vp->v_mount = mp) != NULL)
                TAILQ_INSERT_TAIL(&mp->mnt_vnodelist, vp, v_mntvnodes);
}

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

/*
 * Create a vnode for a character device.
 * Used for console handling.
 */
int
cdevvp(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.
 */
int
getdevvp(dev_t dev, struct vnode **vpp, enum vtype type)
{
        struct vnode *vp;
        struct vnode *nvp;
        int error;

        if (dev == NODEV) {
                *vpp = NULL;
                return (0);
        }
        error = getnewvnode(VT_NON, NULL, &spec_vops, &nvp);
        if (error) {
                *vpp = NULL;
                return (error);
        }
        vp = nvp;
        vp->v_type = type;
        if ((nvp = checkalias(vp, dev, NULL)) != NULL) {
                vput(vp);
                vp = nvp;
        }
        if (vp->v_type == VCHR && cdevsw[major(vp->v_rdev)].d_type == D_TTY)
                vp->v_flag |= VISTTY;
        *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(struct vnode *nvp, dev_t nvp_rdev, struct mount *mp)
{
        struct proc *p = curproc;
        struct vnode *vp;
        struct vnodechain *vchain;

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

        vchain = &speclisth[SPECHASH(nvp_rdev)];
loop:
        SLIST_FOREACH(vp, vchain, 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) {
                        vgonel(vp, p);
                        goto loop;
                }
                if (vget(vp, LK_EXCLUSIVE)) {
                        goto loop;
                }
                break;
        }

        /*
         * Common case is actually in the if statement
         */
        if (vp == NULL || !(vp->v_tag == VT_NON && vp->v_type == VBLK)) {
                nvp->v_specinfo = malloc(sizeof(struct specinfo), M_VNODE,
                        M_WAITOK);
                nvp->v_rdev = nvp_rdev;
                nvp->v_hashchain = vchain;
                nvp->v_specmountpoint = NULL;
                nvp->v_speclockf = NULL;
                nvp->v_specbitmap = NULL;
                if (nvp->v_type == VCHR &&
                    (cdevsw[major(nvp_rdev)].d_flags & D_CLONE) &&
                    (minor(nvp_rdev) >> CLONE_SHIFT == 0)) {
                        if (vp != NULL)
                                nvp->v_specbitmap = vp->v_specbitmap;
                        else
                                nvp->v_specbitmap = malloc(CLONE_MAPSZ,
                                    M_VNODE, M_WAITOK | M_ZERO);
                }
                SLIST_INSERT_HEAD(vchain, nvp, v_specnext);
                if (vp != NULL) {
                        nvp->v_flag |= VALIASED;
                        vp->v_flag |= VALIASED;
                        vput(vp);
                }
                return (NULL);
        }

        /*
         * This code is the uncommon case. It is called in case
         * we found an alias that was VT_NON && vtype of VBLK
         * This means we found a block device that was created
         * using bdevvp.
         * An example of such a vnode is the root partition device vnode
         * created in ffs_mountroot.
         *
         * The vnodes created by bdevvp should not be aliased (why?).
         */

        VOP_UNLOCK(vp);
        vclean(vp, 0, p);
        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. If the vnode lock bit is set,
 * the vnode is being eliminated in vgone. In that case, we
 * cannot grab it, so the process is awakened when the
 * transition is completed, and an error code is returned to
 * indicate that the vnode is no longer usable, possibly
 * having been changed to a new file system type.
 */
int
vget(struct vnode *vp, int flags)
{
        int error, s, onfreelist;

        /*
         * 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.
         */
        mtx_enter(&vnode_mtx);
        if (vp->v_lflag & VXLOCK) {
                if (flags & LK_NOWAIT) {
                        mtx_leave(&vnode_mtx);
                        return (EBUSY);
                }

                vp->v_lflag |= VXWANT;
                msleep_nsec(vp, &vnode_mtx, PINOD, "vget", INFSLP);
                mtx_leave(&vnode_mtx);
                return (ENOENT);
        }
        mtx_leave(&vnode_mtx);

        s = splbio();
        onfreelist = vp->v_bioflag & VBIOONFREELIST;
        if (vp->v_usecount == 0 && onfreelist) {
                if (vp->v_holdcnt > 0)
                        TAILQ_REMOVE(&vnode_hold_list, vp, v_freelist);
                else
                        TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
                vp->v_bioflag &= ~VBIOONFREELIST;
        }
        splx(s);

        vp->v_usecount++;
        if (flags & LK_TYPE_MASK) {
                if ((error = vn_lock(vp, flags)) != 0) {
                        vp->v_usecount--;
                        if (vp->v_usecount == 0 && onfreelist)
                                vputonfreelist(vp);
                }
                return (error);
        }

        return (0);
}


/* Vnode reference. */
void
vref(struct vnode *vp)
{
        KERNEL_ASSERT_LOCKED();

#ifdef DIAGNOSTIC
        if (vp->v_usecount == 0)
                panic("vref used where vget required");
        if (vp->v_type == VNON)
                panic("vref on a VNON vnode");
#endif
        vp->v_usecount++;
}

void
vputonfreelist(struct vnode *vp)
{
        int s;
        struct freelst *lst;

        s = splbio();
#ifdef DIAGNOSTIC
        if (vp->v_usecount != 0)
                panic("Use count is not zero!");

        /*
         * If the hold count is still positive, one or many threads could still
         * be waiting on the vnode lock inside uvn_io().
         */
        if (vp->v_holdcnt == 0 && vp->v_lockcount != 0)
                panic("%s: lock count is not zero", __func__);

        if (vp->v_bioflag & VBIOONFREELIST) {
                vprint("vnode already on free list: ", vp);
                panic("vnode already on free list");
        }
#endif

        vp->v_bioflag |= VBIOONFREELIST;
        vp->v_bioflag &= ~VBIOERROR;

        if (vp->v_holdcnt > 0)
                lst = &vnode_hold_list;
        else
                lst = &vnode_free_list;

        if (vp->v_type == VBAD)
                TAILQ_INSERT_HEAD(lst, vp, v_freelist);
        else
                TAILQ_INSERT_TAIL(lst, vp, v_freelist);

        splx(s);
}

/*
 * vput(), just unlock and vrele()
 */
void
vput(struct vnode *vp)
{
        struct proc *p = curproc;
        int s;

#ifdef DIAGNOSTIC
        if (vp == NULL)
                panic("vput: null vp");
#endif

#ifdef DIAGNOSTIC
        if (vp->v_usecount == 0) {
                vprint("vput: bad ref count", vp);
                panic("vput: ref cnt");
        }
#endif
        vp->v_usecount--;
        KASSERT(vp->v_usecount > 0 || vp->v_uvcount == 0);
        if (vp->v_usecount > 0) {
                VOP_UNLOCK(vp);
                return;
        }

#ifdef DIAGNOSTIC
        if (vp->v_writecount != 0) {
                vprint("vput: bad writecount", vp);
                panic("vput: v_writecount != 0");
        }
#endif

        VOP_INACTIVE(vp, p);

        s = splbio();
        if (vp->v_usecount == 0 && !(vp->v_bioflag & VBIOONFREELIST))
                vputonfreelist(vp);
        splx(s);
}

/*
 * Vnode release - use for active VNODES.
 * If count drops to zero, call inactive routine and return to freelist.
 * Returns 0 if it did not sleep.
 */
int
vrele(struct vnode *vp)
{
        struct proc *p = curproc;
        int s;

#ifdef DIAGNOSTIC
        if (vp == NULL)
                panic("vrele: null vp");
#endif
#ifdef DIAGNOSTIC
        if (vp->v_usecount == 0) {
                vprint("vrele: bad ref count", vp);
                panic("vrele: ref cnt");
        }
#endif
        vp->v_usecount--;
        if (vp->v_usecount > 0) {
                return (0);
        }

#ifdef DIAGNOSTIC
        if (vp->v_writecount != 0) {
                vprint("vrele: bad writecount", vp);
                panic("vrele: v_writecount != 0");
        }
#endif

        if (vn_lock(vp, LK_EXCLUSIVE)) {
#ifdef DIAGNOSTIC
                vprint("vrele: cannot lock", vp);
#endif
                return (1);
        }

        VOP_INACTIVE(vp, p);

        s = splbio();
        if (vp->v_usecount == 0 && !(vp->v_bioflag & VBIOONFREELIST))
                vputonfreelist(vp);
        splx(s);
        return (1);
}

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

        s = splbio();

        /*
         * If it is on the freelist and the hold count is currently
         * zero, move it to the hold list.
         */
        if ((vp->v_bioflag & VBIOONFREELIST) &&
            vp->v_holdcnt == 0 && vp->v_usecount == 0) {
                TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
                TAILQ_INSERT_TAIL(&vnode_hold_list, vp, v_freelist);
        }
        vp->v_holdcnt++;

        splx(s);
}

/* Lose interest in a vnode. */
void
vdrop(struct vnode *vp)
{
        int s;

        s = splbio();

#ifdef DIAGNOSTIC
        if (vp->v_holdcnt == 0)
                panic("vdrop: zero holdcnt");
#endif

        vp->v_holdcnt--;

        /*
         * If it is on the holdlist and the hold count drops to
         * zero, move it to the free list.
         */
        if ((vp->v_bioflag & VBIOONFREELIST) &&
            vp->v_holdcnt == 0 && vp->v_usecount == 0) {
                TAILQ_REMOVE(&vnode_hold_list, vp, v_freelist);
                TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
        }

        splx(s);
}

/*
 * 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.
 */
#ifdef DEBUG_SYSCTL
int busyprt = 0;        /* print out busy vnodes */
struct ctldebug debug_vfs_busyprt = { "vfs_busyprt", &busyprt };
#endif

int
vfs_mount_foreach_vnode(struct mount *mp,
    int (*func)(struct vnode *, void *), void *arg) {
        struct vnode *vp, *nvp;
        int error = 0;

loop:
        TAILQ_FOREACH_SAFE(vp , &mp->mnt_vnodelist, v_mntvnodes, nvp) {
                if (vp->v_mount != mp)
                        goto loop;

                error = func(vp, arg);

                if (error != 0)
                        break;
        }

        return (error);
}

struct vflush_args {
        struct vnode *skipvp;
        int busy;
        int flags;
};

int
vflush_vnode(struct vnode *vp, void *arg)
{
        struct vflush_args *va = arg;
        struct proc *p = curproc;
        int empty, s;

        if (vp == va->skipvp) {
                return (0);
        }

        if ((va->flags & SKIPSYSTEM) && (vp->v_flag & VSYSTEM)) {
                return (0);
        }

        /*
         * If WRITECLOSE is set, only flush out regular file
         * vnodes open for writing.
         */
        if ((va->flags & WRITECLOSE) &&
            (vp->v_writecount == 0 || vp->v_type != VREG)) {
                return (0);
        }

        /*
         * 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) {
                vgonel(vp, p);
                return (0);
        }

        /*
         * 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 (va->flags & FORCECLOSE) {
                if (vp->v_type != VBLK && vp->v_type != VCHR) {
                        vgonel(vp, p);
                } else {
                        vclean(vp, 0, p);
                        vp->v_op = &spec_vops;
                        insmntque(vp, NULL);
                }
                return (0);
        }

        /*
         * If set, this is allowed to ignore vnodes which don't
         * have changes pending to disk.
         * XXX Might be nice to check per-fs "inode" flags, but
         * generally the filesystem is sync'd already, right?
         */
        s = splbio();
        empty = (va->flags & IGNORECLEAN) && LIST_EMPTY(&vp->v_dirtyblkhd);
        splx(s);

        if (empty)
                return (0);

#if defined(DEBUG_SYSCTL) && (defined(DEBUG) || defined(DIAGNOSTIC))
        if (busyprt)
                vprint("vflush: busy vnode", vp);
#endif
        va->busy++;
        return (0);
}

int
vflush(struct mount *mp, struct vnode *skipvp, int flags)
{
        struct vflush_args va;
        va.skipvp = skipvp;
        va.busy = 0;
        va.flags = flags;

        vfs_mount_foreach_vnode(mp, vflush_vnode, &va);

        if (va.busy)
                return (EBUSY);
        return (0);
}

/*
 * Disassociate the underlying file system from a vnode.
 */
void
vclean(struct vnode *vp, int flags, struct proc *p)
{
        int active, do_wakeup = 0;
        int s;

        /*
         * 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++;

        /*
         * Prevent the vnode from being recycled or
         * brought into use while we clean it out.
         */
        mtx_enter(&vnode_mtx);
        if (vp->v_lflag & VXLOCK)
                panic("vclean: deadlock");
        vp->v_lflag |= VXLOCK;

        if (vp->v_lockcount > 0) {
                /*
                 * Ensure that any thread currently waiting on the same lock has
                 * observed that the vnode is about to be exclusively locked
                 * before continuing.
                 */
                msleep_nsec(&vp->v_lockcount, &vnode_mtx, PINOD, "vop_lock",
                    INFSLP);
                KASSERT(vp->v_lockcount == 0);
        }
        mtx_leave(&vnode_mtx);

        /*
         * 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_EXCLUSIVE | LK_DRAIN);

        /*
         * Clean out any VM data associated with the vnode.
         */
        uvm_vnp_terminate(vp);
        /*
         * Clean out any buffers associated with the vnode.
         */
        if (flags & DOCLOSE)
                vinvalbuf(vp, V_SAVE, NOCRED, p, 0, INFSLP);
        /*
         * 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) {
                if (flags & DOCLOSE)
                        VOP_CLOSE(vp, FNONBLOCK, NOCRED, p);
                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);
        }

        /*
         * Reclaim the vnode.
         */
        if (VOP_RECLAIM(vp, p))
                panic("vclean: cannot reclaim");
        if (active) {
                vp->v_usecount--;
                if (vp->v_usecount == 0) {
                        s = splbio();
                        if (vp->v_holdcnt > 0)
                                panic("vclean: not clean");
                        vputonfreelist(vp);
                        splx(s);
                }
        }
        cache_purge(vp);

        /*
         * Done with purge, notify sleepers of the grim news.
         */
        vp->v_op = &dead_vops;
        VN_KNOTE(vp, NOTE_REVOKE);
        vp->v_tag = VT_NON;
#ifdef VFSLCKDEBUG
        vp->v_flag &= ~VLOCKSWORK;
#endif
        mtx_enter(&vnode_mtx);
        vp->v_lflag &= ~VXLOCK;
        if (vp->v_lflag & VXWANT) {
                vp->v_lflag &= ~VXWANT;
                do_wakeup = 1;
        }
        mtx_leave(&vnode_mtx);
        if (do_wakeup)
                wakeup(vp);
}

/*
 * Recycle an unused vnode to the front of the free list.
 */
int
vrecycle(struct vnode *vp, struct proc *p)
{
        if (vp->v_usecount == 0) {
                vgonel(vp, p);
                return (1);
        }
        return (0);
}

/*
 * Eliminate all activity associated with a vnode
 * in preparation for reuse.
 */
void
vgone(struct vnode *vp)
{
        struct proc *p = curproc;
        vgonel(vp, p);
}

/*
 * vgone, with struct proc.
 */
void
vgonel(struct vnode *vp, struct proc *p)
{
        struct vnode *vq;
        struct vnode *vx;
        int s;

        KASSERT(vp->v_uvcount == 0);

        /*
         * If a vgone (or vclean) is already in progress,
         * wait until it is done and return.
         */
        mtx_enter(&vnode_mtx);
        if (vp->v_lflag & VXLOCK) {
                vp->v_lflag |= VXWANT;
                msleep_nsec(vp, &vnode_mtx, PINOD, "vgone", INFSLP);
                mtx_leave(&vnode_mtx);
                return;
        }
        mtx_leave(&vnode_mtx);

        /*
         * Clean out the filesystem specific data.
         */
        vclean(vp, DOCLOSE, p);
        /*
         * Delete from old mount point vnode list, if on one.
         */
        if (vp->v_mount != NULL)
                insmntque(vp, NULL);
        /*
         * If special device, remove it from special device alias list
         * if it is on one.
         */
        if ((vp->v_type == VBLK || vp->v_type == VCHR) &&
            vp->v_specinfo != NULL) {
                if ((vp->v_flag & VALIASED) == 0 && vp->v_type == VCHR &&
                    (cdevsw[major(vp->v_rdev)].d_flags & D_CLONE) &&
                    (minor(vp->v_rdev) >> CLONE_SHIFT == 0)) {
                        free(vp->v_specbitmap, M_VNODE, CLONE_MAPSZ);
                }
                SLIST_REMOVE(vp->v_hashchain, vp, vnode, v_specnext);
                if (vp->v_flag & VALIASED) {
                        vx = NULL;
                        SLIST_FOREACH(vq, vp->v_hashchain, 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;
                }
                lf_purgelocks(&vp->v_speclockf);
                free(vp->v_specinfo, M_VNODE, sizeof(struct specinfo));
                vp->v_specinfo = NULL;
        }
        /*
         * If it is on the freelist and not already at the head,
         * move it to the head of the list.
         */
        vp->v_type = VBAD;

        /*
         * Move onto the free list, unless we were called from
         * getnewvnode and we're not on any free list
         */
        s = splbio();
        if (vp->v_usecount == 0 &&
            (vp->v_bioflag & VBIOONFREELIST)) {
                if (vp->v_holdcnt > 0)
                        panic("vgonel: not clean");

                if (TAILQ_FIRST(&vnode_free_list) != vp) {
                        TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
                        TAILQ_INSERT_HEAD(&vnode_free_list, vp, v_freelist);
                }
        }
        splx(s);
}

/*
 * Lookup a vnode by device number.
 */
int
vfinddev(dev_t dev, enum vtype type, struct vnode **vpp)
{
        struct vnode *vp;
        int rc =0;

        SLIST_FOREACH(vp, &speclisth[SPECHASH(dev)], v_specnext) {
                if (dev != vp->v_rdev || type != vp->v_type)
                        continue;
                *vpp = vp;
                rc = 1;
                break;
        }
        return (rc);
}

/*
 * Revoke all the vnodes corresponding to the specified minor number
 * range (endpoints inclusive) of the specified major.
 */
void
vdevgone(int maj, int minl, int 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(struct vnode *vp)
{
        struct vnode *vq;
        int count;

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

#if defined(DEBUG) || defined(DIAGNOSTIC)
/*
 * Print out a description of a vnode.
 */
static char *typename[] =
   { "VNON", "VREG", "VDIR", "VBLK", "VCHR", "VLNK", "VSOCK", "VFIFO", "VBAD" };

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

        if (label != NULL)
                printf("%s: ", label);
        printf("%p, type %s, use %u, write %u, hold %u,",
                vp, typename[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 & VSYSTEM)
                strlcat(buf, "|VSYSTEM", sizeof buf);
        if (vp->v_lflag & VXLOCK)
                strlcat(buf, "|VXLOCK", sizeof buf);
        if (vp->v_lflag & VXWANT)
                strlcat(buf, "|VXWANT", sizeof buf);
        if (vp->v_bioflag & VBIOWAIT)
                strlcat(buf, "|VBIOWAIT", sizeof buf);
        if (vp->v_bioflag & VBIOONFREELIST)
                strlcat(buf, "|VBIOONFREELIST", sizeof buf);
        if (vp->v_bioflag & VBIOONSYNCLIST)
                strlcat(buf, "|VBIOONSYNCLIST", 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);
        }
}
#endif /* DEBUG || DIAGNOSTIC */

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

        printf("Locked vnodes\n");

        TAILQ_FOREACH(mp, &mountlist, mnt_list) {
                if (vfs_busy(mp, VB_READ|VB_NOWAIT))
                        continue;
                TAILQ_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes) {
                        if (VOP_ISLOCKED(vp))
                                vprint(NULL, vp);
                }
                vfs_unbusy(mp);
        }

}
#endif

#ifndef SMALL_KERNEL
/*
 * Top level filesystem related information gathering.
 */
int
vfs_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
    size_t newlen, struct proc *p)
{
        struct vfsconf *vfsp, *tmpvfsp;
        int ret;

        /* all sysctl names at this level are at least name and field */
        if (namelen < 2)
                return (ENOTDIR);               /* overloaded */

        if (name[0] != VFS_GENERIC) {
                vfsp = vfs_bytypenum(name[0]);
                if (vfsp == NULL || vfsp->vfc_vfsops->vfs_sysctl == NULL)
                        return (EOPNOTSUPP);

                return ((*vfsp->vfc_vfsops->vfs_sysctl)(&name[1], namelen - 1,
                    oldp, oldlenp, newp, newlen, p));
        }

        switch (name[1]) {
        case VFS_MAXTYPENUM:
                return (sysctl_rdint(oldp, oldlenp, newp, maxvfsconf));

        case VFS_CONF:
                if (namelen < 3)
                        return (ENOTDIR);       /* overloaded */

                vfsp = vfs_bytypenum(name[2]);
                if (vfsp == NULL)
                        return (EOPNOTSUPP);

                /* Make a copy, clear out kernel pointers */
                tmpvfsp = malloc(sizeof(*tmpvfsp), M_TEMP, M_WAITOK|M_ZERO);
                memcpy(tmpvfsp, vfsp, sizeof(*tmpvfsp));
                tmpvfsp->vfc_vfsops = NULL;

                ret = sysctl_rdstruct(oldp, oldlenp, newp, tmpvfsp,
                    sizeof(struct vfsconf));

                free(tmpvfsp, M_TEMP, sizeof(*tmpvfsp));
                return (ret);
        case VFS_BCACHESTAT:    /* buffer cache statistics */
                ret = sysctl_rdstruct(oldp, oldlenp, newp, &bcstats,
                    sizeof(struct bcachestats));
                return(ret);
        }
        return (EOPNOTSUPP);
}
#endif /* SMALL_KERNEL */

/*
 * Check to see if a filesystem is mounted on a block device.
 */
int
vfs_mountedon(struct vnode *vp)
{
        struct vnode *vq;
        int error = 0;

        if (vp->v_specmountpoint != NULL)
                return (EBUSY);
        if (vp->v_flag & VALIASED) {
                SLIST_FOREACH(vq, vp->v_hashchain, v_specnext) {
                        if (vq->v_rdev != vp->v_rdev ||
                            vq->v_type != vp->v_type)
                                continue;
                        if (vq->v_specmountpoint != NULL) {
                                error = EBUSY;
                                break;
                        }
                }
        }
        return (error);
}

#ifdef NFSSERVER
/*
 * Build hash lists of net addresses and hang them off the mount point.
 * Called by vfs_export() to set up the lists of export addresses.
 */
int
vfs_hang_addrlist(struct mount *mp, struct netexport *nep,
    struct export_args *argp)
{
        struct netcred *np;
        struct radix_node_head *rnh;
        int nplen, i;
        struct radix_node *rn;
        struct sockaddr *saddr, *smask = NULL;
        int error;

        if (argp->ex_addrlen == 0) {
                if (mp->mnt_flag & MNT_DEFEXPORTED)
                        return (EPERM);
                np = &nep->ne_defexported;
                /* fill in the kernel's ucred from userspace's xucred */
                if ((error = crfromxucred(&np->netc_anon, &argp->ex_anon)))
                        return (error);
                mp->mnt_flag |= MNT_DEFEXPORTED;
                goto finish;
        }
        if (argp->ex_addrlen > MLEN || argp->ex_masklen > MLEN ||
            argp->ex_addrlen < 0 || argp->ex_masklen < 0)
                return (EINVAL);
        nplen = sizeof(struct netcred) + argp->ex_addrlen + argp->ex_masklen;
        np = (struct netcred *)malloc(nplen, M_NETADDR, M_WAITOK|M_ZERO);
        np->netc_len = nplen;
        saddr = (struct sockaddr *)(np + 1);
        error = copyin(argp->ex_addr, saddr, argp->ex_addrlen);
        if (error)
                goto out;
        if (saddr->sa_len > argp->ex_addrlen)
                saddr->sa_len = argp->ex_addrlen;
        if (argp->ex_masklen) {
                smask = (struct sockaddr *)((caddr_t)saddr + argp->ex_addrlen);
                error = copyin(argp->ex_mask, smask, argp->ex_masklen);
                if (error)
                        goto out;
                if (smask->sa_len > argp->ex_masklen)
                        smask->sa_len = argp->ex_masklen;
        }
        /* fill in the kernel's ucred from userspace's xucred */
        if ((error = crfromxucred(&np->netc_anon, &argp->ex_anon)))
                goto out;
        i = saddr->sa_family;
        switch (i) {
        case AF_INET:
                if ((rnh = nep->ne_rtable_inet) == NULL) {
                        if (!rn_inithead((void **)&nep->ne_rtable_inet,
                            offsetof(struct sockaddr_in, sin_addr))) {
                                error = ENOBUFS;
                                goto out;
                        }
                        rnh = nep->ne_rtable_inet;
                }
                break;
        default:
                error = EINVAL;
                goto out;
        }
        rn = rn_addroute(saddr, smask, rnh, np->netc_rnodes, 0);
        if (rn == NULL || np != (struct netcred *)rn) { /* already exists */
                error = EPERM;
                goto out;
        }
finish:
        np->netc_exflags = argp->ex_flags;
        return (0);
out:
        free(np, M_NETADDR, np->netc_len);
        return (error);
}

int
vfs_free_netcred(struct radix_node *rn, void *w, u_int id)
{
        struct radix_node_head *rnh = (struct radix_node_head *)w;
        struct netcred * np = (struct netcred *)rn;

        rn_delete(rn->rn_key, rn->rn_mask, rnh, NULL);
        free(np, M_NETADDR, np->netc_len);
        return (0);
}

/*
 * Free the net address hash lists that are hanging off the mount points.
 */
void
vfs_free_addrlist(struct netexport *nep)
{
        struct radix_node_head *rnh;

        if ((rnh = nep->ne_rtable_inet) != NULL) {
                rn_walktree(rnh, vfs_free_netcred, rnh);
                free(rnh, M_RTABLE, sizeof(*rnh));
                nep->ne_rtable_inet = NULL;
        }
}
#endif /* NFSSERVER */

int
vfs_export(struct mount *mp, struct netexport *nep, struct export_args *argp)
{
#ifdef NFSSERVER
        int error;

        if (argp->ex_flags & MNT_DELEXPORT) {
                vfs_free_addrlist(nep);
                mp->mnt_flag &= ~(MNT_EXPORTED | MNT_DEFEXPORTED);
        }
        if (argp->ex_flags & MNT_EXPORTED) {
                if ((error = vfs_hang_addrlist(mp, nep, argp)) != 0)
                        return (error);
                mp->mnt_flag |= MNT_EXPORTED;
        }
        return (0);
#else
        return (ENOTSUP);
#endif /* NFSSERVER */
}

struct netcred *
vfs_export_lookup(struct mount *mp, struct netexport *nep, struct mbuf *nam)
{
#ifdef NFSSERVER
        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 *);
                        switch(saddr->sa_family) {
                        case AF_INET:
                                rnh = nep->ne_rtable_inet;
                                break;
                        default:
                                rnh = NULL;
                                break;
                        }
                        if (rnh != NULL)
                                np = (struct netcred *)rn_match(saddr, rnh);
                }
                /*
                 * If no address match, use the default if it exists.
                 */
                if (np == NULL && mp->mnt_flag & MNT_DEFEXPORTED)
                        np = &nep->ne_defexported;
        }
        return (np);
#else
        return (NULL);
#endif /* NFSSERVER */
}

/*
 * Do the usual access checking.
 * file_mode, uid and gid are from the vnode in question,
 * while acc_mode and cred are from the VOP_ACCESS parameter list
 */
int
vaccess(enum vtype type, mode_t file_mode, uid_t uid, gid_t gid,
    mode_t acc_mode, struct ucred *cred)
{
        mode_t mask;

        /* User id 0 always gets read/write access. */
        if (cred->cr_uid == 0) {
                /* For VEXEC, at least one of the execute bits must be set. */
                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 (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;
}

int
vnoperm(struct vnode *vp)
{
        if (vp->v_flag & VROOT || vp->v_mount == NULL)
                return 0;

        return (vp->v_mount->mnt_flag & MNT_NOPERM);
}

struct rwlock vfs_stall_lock = RWLOCK_INITIALIZER("vfs_stall");
unsigned int vfs_stalling = 0;

int
vfs_stall(struct proc *p, int stall)
{
        struct mount *mp;
        int allerror = 0, error;

        if (stall) {
                atomic_inc_int(&vfs_stalling);
                rw_enter_write(&vfs_stall_lock);
        }

        /*
         * The loop variable mp is protected by vfs_busy() so that it cannot
         * be unmounted while VFS_SYNC() sleeps.  Traverse forward to keep the
         * lock order consistent with dounmount().
         */
        TAILQ_FOREACH(mp, &mountlist, mnt_list) {
                if (stall) {
                        error = vfs_busy(mp, VB_WRITE|VB_WAIT|VB_DUPOK);
                        if (error) {
                                printf("%s: busy\n", mp->mnt_stat.f_mntonname);
                                allerror = error;
                                continue;
                        }
                        uvm_vnp_sync(mp);
                        error = VFS_SYNC(mp, MNT_WAIT, stall, p->p_ucred, p);
                        if (error) {
                                printf("%s: failed to sync\n",
                                    mp->mnt_stat.f_mntonname);
                                vfs_unbusy(mp);
                                allerror = error;
                                continue;
                        }
                        mp->mnt_flag |= MNT_STALLED;
                } else {
                        if (mp->mnt_flag & MNT_STALLED) {
                                vfs_unbusy(mp);
                                mp->mnt_flag &= ~MNT_STALLED;
                        }
                }
        }

        if (!stall) {
                rw_exit_write(&vfs_stall_lock);
                atomic_dec_int(&vfs_stalling);
        }

        return (allerror);
}

void
vfs_stall_barrier(void)
{
        if (__predict_false(vfs_stalling)) {
                rw_enter_read(&vfs_stall_lock);
                rw_exit_read(&vfs_stall_lock);
        }
}

/*
 * 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(void)
{
        struct mount *mp, *nmp;
        int allerror, error, again = 1;

 retry:
        allerror = 0;
        TAILQ_FOREACH_REVERSE_SAFE(mp, &mountlist, mntlist, mnt_list, nmp) {
                if (vfs_busy(mp, VB_WRITE|VB_NOWAIT))
                        continue;
                /* XXX Here is a race, the next pointer is not locked. */
                if ((error = dounmount(mp, MNT_FORCE, curproc)) != 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");
                if (again) {
                        printf("retrying\n");
                        again = 0;
                        goto retry;
                }
        }
}

/*
 * Sync and unmount file systems before shutting down.
 */
void
vfs_shutdown(struct proc *p)
{
#ifdef ACCOUNTING
        acct_shutdown();
#endif

        printf("syncing disks...");

        if (panicstr == NULL) {
                /* Sync before unmount, in case we hang on something. */
                sys_sync(p, NULL, NULL);
                vfs_unmountall();
        }

#if NSOFTRAID > 0
        sr_quiesce();
#endif

        if (vfs_syncwait(p, 1))
                printf(" giving up\n");
        else
                printf(" done\n");
}

/*
 * perform sync() operation and wait for buffers to flush.
 */
int
vfs_syncwait(struct proc *p, int verbose)
{
        struct buf *bp;
        int iter, nbusy, dcount, s;
#ifdef MULTIPROCESSOR
        int hold_count;
#endif

        sys_sync(p, NULL, NULL);

        /* Wait for sync to finish. */
        dcount = 10000;
        for (iter = 0; iter < 20; iter++) {
                nbusy = 0;
                LIST_FOREACH(bp, &bufhead, b_list) {
                        if ((bp->b_flags & (B_BUSY|B_INVAL|B_READ)) == B_BUSY)
                                nbusy++;
                        /*
                         * With soft updates, some buffers that are
                         * written will be remarked as dirty until other
                         * buffers are written.
                         *
                         * XXX here be dragons. this should really go away
                         * but should be carefully made to go away on it's
                         * own with testing.. XXX
                         */
                        if (bp->b_flags & B_DELWRI) {
                                s = splbio();
                                bufcache_take(bp);
                                buf_acquire(bp);
                                splx(s);
                                nbusy++;
                                bawrite(bp);
                                if (dcount-- <= 0) {
                                        if (verbose)
                                                printf("softdep ");
                                        return 1;
                                }
                        }
                }
                if (nbusy == 0)
                        break;
                if (verbose)
                        printf("%d ", nbusy);
#ifdef MULTIPROCESSOR
                if (_kernel_lock_held())
                        hold_count = __mp_release_all(&kernel_lock);
                else
                        hold_count = 0;
#endif
                DELAY(40000 * iter);
#ifdef MULTIPROCESSOR
                if (hold_count)
                        __mp_acquire_count(&kernel_lock, hold_count);
#endif
        }

        return nbusy;
}


/*
 * Routines dealing with vnodes and buffers
 */

/*
 * Wait for all outstanding I/Os to complete
 *
 * Manipulates v_numoutput. Must be called at splbio()
 */
int
vwaitforio(struct vnode *vp, int slpflag, char *wmesg, uint64_t timeo)
{
        int error = 0;

        splassert(IPL_BIO);

        while (vp->v_numoutput) {
                vp->v_bioflag |= VBIOWAIT;
                error = tsleep_nsec(&vp->v_numoutput,
                    slpflag | (PRIBIO + 1), wmesg, timeo);
                if (error)
                        break;
        }

        return (error);
}

/*
 * Update outstanding I/O count and do wakeup if requested.
 *
 * Manipulates v_numoutput. Must be called at splbio()
 */
void
vwakeup(struct vnode *vp)
{
        splassert(IPL_BIO);

        if (vp != NULL) {
                if (vp->v_numoutput-- == 0)
                        panic("vwakeup: neg numoutput");
                if ((vp->v_bioflag & VBIOWAIT) && vp->v_numoutput == 0) {
                        vp->v_bioflag &= ~VBIOWAIT;
                        wakeup(&vp->v_numoutput);
                }
        }
}

/*
 * Flush out and invalidate all buffers associated with a vnode.
 * Called with the underlying object locked.
 */
int
vinvalbuf(struct vnode *vp, int flags, struct ucred *cred, struct proc *p,
    int slpflag, uint64_t slptimeo)
{
        struct buf *bp;
        struct buf *nbp, *blist;
        int s, error;

#ifdef VFSLCKDEBUG
        if ((vp->v_flag & VLOCKSWORK) && !VOP_ISLOCKED(vp))
                panic("%s: vp isn't locked, vp %p", __func__, vp);
#endif

        if (flags & V_SAVE) {
                s = splbio();
                vwaitforio(vp, 0, "vinvalbuf", INFSLP);
                if (!LIST_EMPTY(&vp->v_dirtyblkhd)) {
                        splx(s);
                        if ((error = VOP_FSYNC(vp, cred, MNT_WAIT, p)) != 0)
                                return (error);
                        s = splbio();
                        if (vp->v_numoutput > 0 ||
                            !LIST_EMPTY(&vp->v_dirtyblkhd))
                                panic("%s: dirty bufs, vp %p", __func__, vp);
                }
                splx(s);
        }
loop:
        s = splbio();
        for (;;) {
                int count = 0;
                if ((blist = LIST_FIRST(&vp->v_cleanblkhd)) &&
                    (flags & V_SAVEMETA))
                        while (blist && blist->b_lblkno < 0)
                                blist = LIST_NEXT(blist, b_vnbufs);
                if (blist == NULL &&
                    (blist = LIST_FIRST(&vp->v_dirtyblkhd)) &&
                    (flags & V_SAVEMETA))
                        while (blist && blist->b_lblkno < 0)
                                blist = LIST_NEXT(blist, b_vnbufs);
                if (!blist)
                        break;

                for (bp = blist; bp; bp = nbp) {
                        nbp = LIST_NEXT(bp, b_vnbufs);
                        if (flags & V_SAVEMETA && bp->b_lblkno < 0)
                                continue;
                        if (bp->b_flags & B_BUSY) {
                                bp->b_flags |= B_WANTED;
                                error = tsleep_nsec(bp, slpflag | (PRIBIO + 1),
                                    "vinvalbuf", slptimeo);
                                if (error) {
                                        splx(s);
                                        return (error);
                                }
                                break;
                        }
                        bufcache_take(bp);
                        /*
                         * 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)) {
                                buf_acquire(bp);
                                splx(s);
                                (void) VOP_BWRITE(bp);
                                goto loop;
                        }
                        buf_acquire_nomap(bp);
                        bp->b_flags |= B_INVAL;
                        brelse(bp);
                        count++;
                        /*
                         * XXX Temporary workaround XXX
                         *
                         * If this is a gigantisch vnode and we are
                         * trashing a ton of buffers, drop the lock
                         * and yield every so often. The longer term
                         * fix is to add a separate list for these
                         * invalid buffers so we don't have to do the
                         * work to free these here.
                         */
                        if (count > 100) {
                                splx(s);
                                sched_pause(yield);
                                goto loop;
                        }
                }
        }
        if (!(flags & V_SAVEMETA) &&
            (!LIST_EMPTY(&vp->v_dirtyblkhd) || !LIST_EMPTY(&vp->v_cleanblkhd)))
                panic("%s: flush failed, vp %p", __func__, vp);
        splx(s);
        return (0);
}

void
vflushbuf(struct vnode *vp, int sync)
{
        struct buf *bp, *nbp;
        int s;

loop:
        s = splbio();
        LIST_FOREACH_SAFE(bp, &vp->v_dirtyblkhd, b_vnbufs, nbp) {
                if ((bp->b_flags & B_BUSY))
                        continue;
                if ((bp->b_flags & B_DELWRI) == 0)
                        panic("vflushbuf: not dirty");
                bufcache_take(bp);
                buf_acquire(bp);
                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;
        }
        vwaitforio(vp, 0, "vflushbuf", INFSLP);
        if (!LIST_EMPTY(&vp->v_dirtyblkhd)) {
                splx(s);
#ifdef DIAGNOSTIC
                vprint("vflushbuf: dirty", vp);
#endif
                goto loop;
        }
        splx(s);
}

/*
 * Associate a buffer with a vnode.
 *
 * Manipulates buffer vnode queues. Must be called at splbio().
 */
void
bgetvp(struct vnode *vp, struct buf *bp)
{
        splassert(IPL_BIO);


        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.
         */
        bufinsvn(bp, &vp->v_cleanblkhd);
}

/*
 * Disassociate a buffer from a vnode.
 *
 * Manipulates vnode buffer queues. Must be called at splbio().
 */
void
brelvp(struct buf *bp)
{
        struct vnode *vp;

        splassert(IPL_BIO);

        if ((vp = bp->b_vp) == (struct vnode *) 0)
                panic("brelvp: NULL");
        /*
         * Delete from old vnode list, if on one.
         */
        if (LIST_NEXT(bp, b_vnbufs) != NOLIST)
                bufremvn(bp);
        if ((vp->v_bioflag & VBIOONSYNCLIST) &&
            LIST_EMPTY(&vp->v_dirtyblkhd)) {
                vp->v_bioflag &= ~VBIOONSYNCLIST;
                LIST_REMOVE(vp, v_synclist);
        }
        bp->b_vp = NULL;

        vdrop(vp);
}

/*
 * Replaces the current vnode associated with the buffer, if any,
 * with a new vnode.
 *
 * If an output I/O is pending on the buffer, the old vnode
 * I/O count is adjusted.
 *
 * Ignores vnode buffer queues. Must be called at splbio().
 */
void
buf_replacevnode(struct buf *bp, struct vnode *newvp)
{
        struct vnode *oldvp = bp->b_vp;

        splassert(IPL_BIO);

        if (oldvp)
                brelvp(bp);

        if ((bp->b_flags & (B_READ | B_DONE)) == 0) {
                newvp->v_numoutput++;   /* put it on swapdev */
                vwakeup(oldvp);
        }

        bgetvp(newvp, bp);
        bufremvn(bp);
}

/*
 * Used to assign buffers to the appropriate clean or dirty list on
 * the vnode and to add newly dirty vnodes to the appropriate
 * filesystem syncer list.
 *
 * Manipulates vnode buffer queues. Must be called at splbio().
 */
void
reassignbuf(struct buf *bp)
{
        struct buflists *listheadp;
        int delay;
        struct vnode *vp = bp->b_vp;

        splassert(IPL_BIO);

        /*
         * 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 = &vp->v_cleanblkhd;
                if ((vp->v_bioflag & VBIOONSYNCLIST) &&
                    LIST_EMPTY(&vp->v_dirtyblkhd)) {
                        vp->v_bioflag &= ~VBIOONSYNCLIST;
                        LIST_REMOVE(vp, v_synclist);
                }
        } else {
                listheadp = &vp->v_dirtyblkhd;
                if ((vp->v_bioflag & VBIOONSYNCLIST) == 0) {
                        switch (vp->v_type) {
                        case VDIR:
                                delay = syncdelay / 2;
                                break;
                        case VBLK:
                                if (vp->v_specmountpoint != NULL) {
                                        delay = syncdelay / 3;
                                        break;
                                }
                                /* FALLTHROUGH */
                        default:
                                delay = syncdelay;
                        }
                        vn_syncer_add_to_worklist(vp, delay);
                }
        }
        bufinsvn(bp, listheadp);
}

#ifdef DDB
#include <machine/db_machdep.h>
#include <ddb/db_interface.h>

void
vfs_buf_print(void *b, int full,
    int (*pr)(const char *, ...) __attribute__((__format__(__kprintf__,1,2))))
{
        struct buf *bp = b;

        (*pr)("  vp %p lblkno 0x%llx blkno 0x%llx dev 0x%x\n"
              "  proc %p error %d flags %lb\n",
            bp->b_vp, (int64_t)bp->b_lblkno, (int64_t)bp->b_blkno, bp->b_dev,
            bp->b_proc, bp->b_error, bp->b_flags, B_BITS);

        (*pr)("  bufsize 0x%lx bcount 0x%lx resid 0x%lx\n"
              "  data %p saveaddr %p iodone %p\n",
            bp->b_bufsize, bp->b_bcount, (long)bp->b_resid,
            bp->b_data, bp->b_saveaddr,
            bp->b_iodone);

        (*pr)("  dirty {off 0x%x end 0x%x} valid {off 0x%x end 0x%x}\n",
            bp->b_dirtyoff, bp->b_dirtyend, bp->b_validoff, bp->b_validend);

}

const char *vtypes[] = { VTYPE_NAMES };
const char *vtags[] = { VTAG_NAMES };

void
vfs_vnode_print(void *v, int full,
    int (*pr)(const char *, ...) __attribute__((__format__(__kprintf__,1,2))))
{
        struct vnode *vp = v;

        (*pr)("tag %s(%d) type %s(%d) mount %p typedata %p\n",
              (u_int)vp->v_tag >= nitems(vtags)? "<unk>":vtags[vp->v_tag],
              vp->v_tag,
              (u_int)vp->v_type >= nitems(vtypes)? "<unk>":vtypes[vp->v_type],
              vp->v_type, vp->v_mount, vp->v_mountedhere);

        (*pr)("data %p usecount %d writecount %d holdcnt %d numoutput %d\n",
              vp->v_data, vp->v_usecount, vp->v_writecount,
              vp->v_holdcnt, vp->v_numoutput);

        /* uvm_object_printit(&vp->v_uobj, full, pr); */

        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(struct mount *mp, int full,
    int (*pr)(const char *, ...) __attribute__((__format__(__kprintf__,1,2))))
{
        struct vfsconf *vfc = mp->mnt_vfc;
        struct vnode *vp;
        int cnt;

        (*pr)("flags %b\nvnodecovered %p syncer %p data %p\n",
            mp->mnt_flag, MNT_BITS,
            mp->mnt_vnodecovered, mp->mnt_syncer, mp->mnt_data);

        (*pr)("vfsconf: ops %p name \"%s\" num %d ref %u flags 0x%x\n",
            vfc->vfc_vfsops, vfc->vfc_name, vfc->vfc_typenum,
            vfc->vfc_refcount, vfc->vfc_flags);

        (*pr)("statvfs cache: bsize %x iosize %x\n"
            "blocks %llu free %llu avail %lld\n",
            mp->mnt_stat.f_bsize, mp->mnt_stat.f_iosize, mp->mnt_stat.f_blocks,
            mp->mnt_stat.f_bfree, mp->mnt_stat.f_bavail);

        (*pr)("  files %llu ffiles %llu favail %lld\n", mp->mnt_stat.f_files,
            mp->mnt_stat.f_ffree, mp->mnt_stat.f_favail);

        (*pr)("  f_fsidx {0x%x, 0x%x} owner %u ctime 0x%llx\n",
            mp->mnt_stat.f_fsid.val[0], mp->mnt_stat.f_fsid.val[1],
            mp->mnt_stat.f_owner, mp->mnt_stat.f_ctime);

        (*pr)("  syncwrites %llu asyncwrites = %llu\n",
            mp->mnt_stat.f_syncwrites, mp->mnt_stat.f_asyncwrites);

        (*pr)("  syncreads %llu asyncreads = %llu\n",
            mp->mnt_stat.f_syncreads, mp->mnt_stat.f_asyncreads);

        (*pr)("  fstype \"%s\" mnton \"%s\" mntfrom \"%s\" mntspec \"%s\"\n",
            mp->mnt_stat.f_fstypename, mp->mnt_stat.f_mntonname,
            mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntfromspec);

        (*pr)("locked vnodes:");
        /* XXX would take mountlist lock, except ddb has no context */
        cnt = 0;
        TAILQ_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes) {
                if (VOP_ISLOCKED(vp)) {
                        if (cnt == 0)
                                (*pr)("\n  %p", vp);
                        else if ((cnt % (72 / (sizeof(void *) * 2 + 4))) == 0)
                                (*pr)(",\n  %p", vp);
                        else
                                (*pr)(", %p", vp);
                        cnt++;
                }
        }
        (*pr)("\n");

        if (full) {
                (*pr)("all vnodes:");
                /* XXX would take mountlist lock, except ddb has no context */
                cnt = 0;
                TAILQ_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes) {
                        if (cnt == 0)
                                (*pr)("\n  %p", vp);
                        else if ((cnt % (72 / (sizeof(void *) * 2 + 4))) == 0)
                                (*pr)(",\n  %p", vp);
                        else
                                (*pr)(", %p", vp);
                        cnt++;
                }
                (*pr)("\n");
        }
}
#endif /* DDB */

void
copy_statfs_info(struct statfs *sbp, const struct mount *mp)
{
        const struct statfs *mbp;

        strncpy(sbp->f_fstypename, mp->mnt_vfc->vfc_name, MFSNAMELEN);

        if (sbp == (mbp = &mp->mnt_stat))
                return;

        sbp->f_fsid = mbp->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_syncreads = mbp->f_syncreads;
        sbp->f_asyncreads = mbp->f_asyncreads;
        sbp->f_namemax = mbp->f_namemax;
        memcpy(sbp->f_mntonname, mp->mnt_stat.f_mntonname, MNAMELEN);
        memcpy(sbp->f_mntfromname, mp->mnt_stat.f_mntfromname, MNAMELEN);
        memcpy(sbp->f_mntfromspec, mp->mnt_stat.f_mntfromspec, MNAMELEN);
        memcpy(&sbp->mount_info, &mp->mnt_stat.mount_info,
            sizeof(union mount_info));
}