Expand PMF_FN_* macros.

[netbsd-mini2440.git] / sys / kern / vfs_subr.c

/*      $NetBSD: vfs_subr.c,v 1.394 2010/01/08 11:35:10 pooka Exp $     */

/*-
 * Copyright (c) 1997, 1998, 2004, 2005, 2007, 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
 * NASA Ames Research Center, by Charles M. Hannum, and by Andrew Doran.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)vfs_subr.c  8.13 (Berkeley) 4/18/94
 */

/*
 * Note on v_usecount and locking:
 *
 * At nearly all points it is known that v_usecount could be zero, the
 * vnode interlock will be held.
 *
 * To change v_usecount away from zero, the interlock must be held.  To
 * change from a non-zero value to zero, again the interlock must be
 * held.
 *
 * There's a flag bit, VC_XLOCK, embedded in v_usecount.
 * To raise v_usecount, if the VC_XLOCK bit is set in it, the interlock
 * must be held.
 * To modify the VC_XLOCK bit, the interlock must be held.
 * We always keep the usecount (v_usecount & VC_MASK) non-zero while the
 * VC_XLOCK bit is set.
 *
 * Unless the VC_XLOCK bit is set, changing the usecount from a non-zero
 * value to a non-zero value can safely be done using atomic operations,
 * without the interlock held.
 * Even if the VC_XLOCK bit is set, decreasing the usecount to a non-zero
 * value can be done using atomic operations, without the interlock held.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_subr.c,v 1.394 2010/01/08 11:35:10 pooka Exp $");

#include "opt_ddb.h"
#include "opt_compat_netbsd.h"
#include "opt_compat_43.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/mount.h>
#include <sys/fcntl.h>
#include <sys/vnode.h>
#include <sys/stat.h>
#include <sys/namei.h>
#include <sys/ucred.h>
#include <sys/buf.h>
#include <sys/errno.h>
#include <sys/kmem.h>
#include <sys/syscallargs.h>
#include <sys/device.h>
#include <sys/filedesc.h>
#include <sys/kauth.h>
#include <sys/atomic.h>
#include <sys/kthread.h>
#include <sys/wapbl.h>

#include <miscfs/genfs/genfs.h>
#include <miscfs/specfs/specdev.h>
#include <miscfs/syncfs/syncfs.h>

#include <uvm/uvm.h>
#include <uvm/uvm_readahead.h>
#include <uvm/uvm_ddb.h>

#include <sys/sysctl.h>

const enum vtype iftovt_tab[16] = {
        VNON, VFIFO, VCHR, VNON, VDIR, VNON, VBLK, VNON,
        VREG, VNON, VLNK, VNON, VSOCK, VNON, VNON, VBAD,
};
const int       vttoif_tab[9] = {
        0, S_IFREG, S_IFDIR, S_IFBLK, S_IFCHR, S_IFLNK,
        S_IFSOCK, S_IFIFO, S_IFMT,
};

/*
 * Insq/Remq for the vnode usage lists.
 */
#define bufinsvn(bp, dp)        LIST_INSERT_HEAD(dp, bp, b_vnbufs)
#define bufremvn(bp) {                                                  \
        LIST_REMOVE(bp, b_vnbufs);                                      \
        (bp)->b_vnbufs.le_next = NOLIST;                                \
}

int doforce = 1;                /* 1 => permit forcible unmounting */
int prtactive = 0;              /* 1 => print out reclaim of active vnodes */

static vnodelst_t vnode_free_list = TAILQ_HEAD_INITIALIZER(vnode_free_list);
static vnodelst_t vnode_hold_list = TAILQ_HEAD_INITIALIZER(vnode_hold_list);
static vnodelst_t vrele_list = TAILQ_HEAD_INITIALIZER(vrele_list);

struct mntlist mountlist =                      /* mounted filesystem list */
    CIRCLEQ_HEAD_INITIALIZER(mountlist);

u_int numvnodes;
static specificdata_domain_t mount_specificdata_domain;

static int vrele_pending;
static int vrele_gen;
static kmutex_t vrele_lock;
static kcondvar_t vrele_cv;
static lwp_t *vrele_lwp;

static uint64_t mountgen = 0;
static kmutex_t mountgen_lock;

kmutex_t mountlist_lock;
kmutex_t mntid_lock;
kmutex_t mntvnode_lock;
kmutex_t vnode_free_list_lock;
kmutex_t vfs_list_lock;

static pool_cache_t vnode_cache;

/*
 * These define the root filesystem and device.
 */
struct vnode *rootvnode;
struct device *root_device;                     /* root device */

/*
 * Local declarations.
 */

static void vrele_thread(void *);
static void insmntque(vnode_t *, struct mount *);
static int getdevvp(dev_t, vnode_t **, enum vtype);
static vnode_t *getcleanvnode(void);
void vpanic(vnode_t *, const char *);
static void vfs_shutdown1(struct lwp *);

#ifdef DEBUG 
void printlockedvnodes(void);
#endif

#ifdef DIAGNOSTIC
void
vpanic(vnode_t *vp, const char *msg)
{

        vprint(NULL, vp);
        panic("%s\n", msg);
}
#else
#define vpanic(vp, msg) /* nothing */
#endif

void
vn_init1(void)
{

        vnode_cache = pool_cache_init(sizeof(struct vnode), 0, 0, 0, "vnodepl",
            NULL, IPL_NONE, NULL, NULL, NULL);
        KASSERT(vnode_cache != NULL);

        /* Create deferred release thread. */
        mutex_init(&vrele_lock, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&vrele_cv, "vrele");
        if (kthread_create(PRI_VM, KTHREAD_MPSAFE, NULL, vrele_thread,
            NULL, &vrele_lwp, "vrele"))
                panic("fork vrele");
}

/*
 * Initialize the vnode management data structures.
 */
void
vntblinit(void)
{

        mutex_init(&mountgen_lock, MUTEX_DEFAULT, IPL_NONE);
        mutex_init(&mountlist_lock, MUTEX_DEFAULT, IPL_NONE);
        mutex_init(&mntid_lock, MUTEX_DEFAULT, IPL_NONE);
        mutex_init(&mntvnode_lock, MUTEX_DEFAULT, IPL_NONE);
        mutex_init(&vnode_free_list_lock, MUTEX_DEFAULT, IPL_NONE);
        mutex_init(&vfs_list_lock, MUTEX_DEFAULT, IPL_NONE);

        mount_specificdata_domain = specificdata_domain_create();

        /* Initialize the filesystem syncer. */
        vn_initialize_syncerd();
        vn_init1();
}

int
vfs_drainvnodes(long target, struct lwp *l)
{

        while (numvnodes > target) {
                vnode_t *vp;

                mutex_enter(&vnode_free_list_lock);
                vp = getcleanvnode();
                if (vp == NULL)
                        return EBUSY; /* give up */
                ungetnewvnode(vp);
        }

        return 0;
}

/*
 * Lookup a mount point by filesystem identifier.
 *
 * XXX Needs to add a reference to the mount point.
 */
struct mount *
vfs_getvfs(fsid_t *fsid)
{
        struct mount *mp;

        mutex_enter(&mountlist_lock);
        CIRCLEQ_FOREACH(mp, &mountlist, mnt_list) {
                if (mp->mnt_stat.f_fsidx.__fsid_val[0] == fsid->__fsid_val[0] &&
                    mp->mnt_stat.f_fsidx.__fsid_val[1] == fsid->__fsid_val[1]) {
                        mutex_exit(&mountlist_lock);
                        return (mp);
                }
        }
        mutex_exit(&mountlist_lock);
        return ((struct mount *)0);
}

/*
 * Drop a reference to a mount structure, freeing if the last reference.
 */
void
vfs_destroy(struct mount *mp)
{

        if (__predict_true((int)atomic_dec_uint_nv(&mp->mnt_refcnt) > 0)) {
                return;
        }

        /*
         * Nothing else has visibility of the mount: we can now
         * free the data structures.
         */
        KASSERT(mp->mnt_refcnt == 0);
        specificdata_fini(mount_specificdata_domain, &mp->mnt_specdataref);
        rw_destroy(&mp->mnt_unmounting);
        mutex_destroy(&mp->mnt_updating);
        mutex_destroy(&mp->mnt_renamelock);
        if (mp->mnt_op != NULL) {
                vfs_delref(mp->mnt_op);
        }
        kmem_free(mp, sizeof(*mp));
}

/*
 * grab a vnode from freelist and clean it.
 */
vnode_t *
getcleanvnode(void)
{
        vnode_t *vp;
        vnodelst_t *listhd;

        KASSERT(mutex_owned(&vnode_free_list_lock));

retry:
        listhd = &vnode_free_list;
try_nextlist:
        TAILQ_FOREACH(vp, listhd, v_freelist) {
                /*
                 * It's safe to test v_usecount and v_iflag
                 * without holding the interlock here, since
                 * these vnodes should never appear on the
                 * lists.
                 */
                if (vp->v_usecount != 0) {
                        vpanic(vp, "free vnode isn't");
                }
                if ((vp->v_iflag & VI_CLEAN) != 0) {
                        vpanic(vp, "clean vnode on freelist");
                }
                if (vp->v_freelisthd != listhd) {
                        printf("vnode sez %p, listhd %p\n", vp->v_freelisthd, listhd);
                        vpanic(vp, "list head mismatch");
                }
                if (!mutex_tryenter(&vp->v_interlock))
                        continue;
                /*
                 * Our lwp might hold the underlying vnode
                 * locked, so don't try to reclaim a VI_LAYER
                 * node if it's locked.
                 */
                if ((vp->v_iflag & VI_XLOCK) == 0 &&
                    ((vp->v_iflag & VI_LAYER) == 0 || VOP_ISLOCKED(vp) == 0)) {
                        break;
                }
                mutex_exit(&vp->v_interlock);
        }

        if (vp == NULL) {
                if (listhd == &vnode_free_list) {
                        listhd = &vnode_hold_list;
                        goto try_nextlist;
                }
                mutex_exit(&vnode_free_list_lock);
                return NULL;
        }

        /* Remove it from the freelist. */
        TAILQ_REMOVE(listhd, vp, v_freelist);
        vp->v_freelisthd = NULL;
        mutex_exit(&vnode_free_list_lock);

        if (vp->v_usecount != 0) {
                /*
                 * was referenced again before we got the interlock
                 * Don't return to freelist - the holder of the last
                 * reference will destroy it.
                 */
                mutex_exit(&vp->v_interlock);
                mutex_enter(&vnode_free_list_lock);
                goto retry;
        }

        /*
         * The vnode is still associated with a file system, so we must
         * clean it out before reusing it.  We need to add a reference
         * before doing this.  If the vnode gains another reference while
         * being cleaned out then we lose - retry.
         */
        atomic_add_int(&vp->v_usecount, 1 + VC_XLOCK);
        vclean(vp, DOCLOSE);
        KASSERT(vp->v_usecount >= 1 + VC_XLOCK);
        atomic_add_int(&vp->v_usecount, -VC_XLOCK);
        if (vp->v_usecount == 1) {
                /* We're about to dirty it. */
                vp->v_iflag &= ~VI_CLEAN;
                mutex_exit(&vp->v_interlock);
                if (vp->v_type == VBLK || vp->v_type == VCHR) {
                        spec_node_destroy(vp);
                }
                vp->v_type = VNON;
        } else {
                /*
                 * Don't return to freelist - the holder of the last
                 * reference will destroy it.
                 */
                vrelel(vp, 0); /* releases vp->v_interlock */
                mutex_enter(&vnode_free_list_lock);
                goto retry;
        }

        if (vp->v_data != NULL || vp->v_uobj.uo_npages != 0 ||
            !TAILQ_EMPTY(&vp->v_uobj.memq)) {
                vpanic(vp, "cleaned vnode isn't");
        }
        if (vp->v_numoutput != 0) {
                vpanic(vp, "clean vnode has pending I/O's");
        }
        if ((vp->v_iflag & VI_ONWORKLST) != 0) {
                vpanic(vp, "clean vnode on syncer list");
        }

        return vp;
}

/*
 * Mark a mount point as busy, and gain a new reference to it.  Used to
 * prevent the file system from being unmounted during critical sections.
 *
 * => The caller must hold a pre-existing reference to the mount.
 * => Will fail if the file system is being unmounted, or is unmounted.
 */
int
vfs_busy(struct mount *mp, struct mount **nextp)
{

        KASSERT(mp->mnt_refcnt > 0);

        if (__predict_false(!rw_tryenter(&mp->mnt_unmounting, RW_READER))) {
                if (nextp != NULL) {
                        KASSERT(mutex_owned(&mountlist_lock));
                        *nextp = CIRCLEQ_NEXT(mp, mnt_list);
                }
                return EBUSY;
        }
        if (__predict_false((mp->mnt_iflag & IMNT_GONE) != 0)) {
                rw_exit(&mp->mnt_unmounting);
                if (nextp != NULL) {
                        KASSERT(mutex_owned(&mountlist_lock));
                        *nextp = CIRCLEQ_NEXT(mp, mnt_list);
                }
                return ENOENT;
        }
        if (nextp != NULL) {
                mutex_exit(&mountlist_lock);
        }
        atomic_inc_uint(&mp->mnt_refcnt);
        return 0;
}

/*
 * Unbusy a busy filesystem.
 *
 * => If keepref is true, preserve reference added by vfs_busy().
 * => If nextp != NULL, acquire mountlist_lock.
 */
void
vfs_unbusy(struct mount *mp, bool keepref, struct mount **nextp)
{

        KASSERT(mp->mnt_refcnt > 0);

        if (nextp != NULL) {
                mutex_enter(&mountlist_lock);
        }
        rw_exit(&mp->mnt_unmounting);
        if (!keepref) {
                vfs_destroy(mp);
        }
        if (nextp != NULL) {
                KASSERT(mutex_owned(&mountlist_lock));
                *nextp = CIRCLEQ_NEXT(mp, mnt_list);
        }
}

struct mount *
vfs_mountalloc(struct vfsops *vfsops, struct vnode *vp)
{
        int error;
        struct mount *mp;

        mp = kmem_zalloc(sizeof(*mp), KM_SLEEP);
        if (mp == NULL)
                return NULL;

        mp->mnt_op = vfsops;
        mp->mnt_refcnt = 1;
        TAILQ_INIT(&mp->mnt_vnodelist);
        rw_init(&mp->mnt_unmounting);
        mutex_init(&mp->mnt_renamelock, MUTEX_DEFAULT, IPL_NONE);
        mutex_init(&mp->mnt_updating, MUTEX_DEFAULT, IPL_NONE);
        error = vfs_busy(mp, NULL);
        KASSERT(error == 0);
        mp->mnt_vnodecovered = vp;
        mount_initspecific(mp);

        mutex_enter(&mountgen_lock);
        mp->mnt_gen = mountgen++;
        mutex_exit(&mountgen_lock);

        return mp;
}

/*
 * 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(const char *fstypename, const char *devname,
    struct mount **mpp)
{
        struct vfsops *vfsp = NULL;
        struct mount *mp;

        mutex_enter(&vfs_list_lock);
        LIST_FOREACH(vfsp, &vfs_list, vfs_list)
                if (!strncmp(vfsp->vfs_name, fstypename, 
                    sizeof(mp->mnt_stat.f_fstypename)))
                        break;
        if (vfsp == NULL) {
                mutex_exit(&vfs_list_lock);
                return (ENODEV);
        }
        vfsp->vfs_refcount++;
        mutex_exit(&vfs_list_lock);

        if ((mp = vfs_mountalloc(vfsp, NULL)) == NULL)
                return ENOMEM;
        mp->mnt_flag = MNT_RDONLY;
        (void)strlcpy(mp->mnt_stat.f_fstypename, vfsp->vfs_name,
            sizeof(mp->mnt_stat.f_fstypename));
        mp->mnt_stat.f_mntonname[0] = '/';
        mp->mnt_stat.f_mntonname[1] = '\0';
        mp->mnt_stat.f_mntfromname[sizeof(mp->mnt_stat.f_mntfromname) - 1] =
            '\0';
        (void)copystr(devname, mp->mnt_stat.f_mntfromname,
            sizeof(mp->mnt_stat.f_mntfromname) - 1, 0);
        *mpp = mp;
        return (0);
}

/*
 * Routines having to do with the management of the vnode table.
 */
extern int (**dead_vnodeop_p)(void *);

/*
 * Return the next vnode from the free list.
 */
int
getnewvnode(enum vtagtype tag, struct mount *mp, int (**vops)(void *),
            vnode_t **vpp)
{
        struct uvm_object *uobj;
        static int toggle;
        vnode_t *vp;
        int error = 0, tryalloc;

 try_again:
        if (mp != NULL) {
                /*
                 * Mark filesystem busy while we're creating a
                 * vnode.  If unmount is in progress, this will
                 * fail.
                 */
                error = vfs_busy(mp, NULL);
                if (error)
                        return error;
        }

        /*
         * We must choose whether to allocate a new vnode or recycle an
         * existing one. The criterion for allocating a new one is that
         * the total number of vnodes is less than the number desired or
         * there are no vnodes on either free list. Generally we only
         * want to recycle vnodes that have no buffers associated with
         * them, so we look first on the vnode_free_list. If it is empty,
         * we next consider vnodes with referencing buffers on the
         * vnode_hold_list. The toggle ensures that half the time we
         * will use a buffer from the vnode_hold_list, and half the time
         * we will allocate a new one unless the list has grown to twice
         * the desired size. We are reticent to recycle vnodes from the
         * vnode_hold_list because we will lose the identity of all its
         * referencing buffers.
         */

        vp = NULL;

        mutex_enter(&vnode_free_list_lock);

        toggle ^= 1;
        if (numvnodes > 2 * desiredvnodes)
                toggle = 0;

        tryalloc = numvnodes < desiredvnodes ||
            (TAILQ_FIRST(&vnode_free_list) == NULL &&
             (TAILQ_FIRST(&vnode_hold_list) == NULL || toggle));

        if (tryalloc) {
                numvnodes++;
                mutex_exit(&vnode_free_list_lock);
                if ((vp = vnalloc(NULL)) == NULL) {
                        mutex_enter(&vnode_free_list_lock);
                        numvnodes--;
                } else
                        vp->v_usecount = 1;
        }

        if (vp == NULL) {
                vp = getcleanvnode();
                if (vp == NULL) {
                        if (mp != NULL) {
                                vfs_unbusy(mp, false, NULL);
                        }
                        if (tryalloc) {
                                printf("WARNING: unable to allocate new "
                                    "vnode, retrying...\n");
                                kpause("newvn", false, hz, NULL);
                                goto try_again;
                        }
                        tablefull("vnode", "increase kern.maxvnodes or NVNODE");
                        *vpp = 0;
                        return (ENFILE);
                }
                vp->v_iflag = 0;
                vp->v_vflag = 0;
                vp->v_uflag = 0;
                vp->v_socket = NULL;
        }

        KASSERT(vp->v_usecount == 1);
        KASSERT(vp->v_freelisthd == NULL);
        KASSERT(LIST_EMPTY(&vp->v_nclist));
        KASSERT(LIST_EMPTY(&vp->v_dnclist));

        vp->v_type = VNON;
        vp->v_vnlock = &vp->v_lock;
        vp->v_tag = tag;
        vp->v_op = vops;
        insmntque(vp, mp);
        *vpp = vp;
        vp->v_data = 0;

        /*
         * initialize uvm_object within vnode.
         */

        uobj = &vp->v_uobj;
        KASSERT(uobj->pgops == &uvm_vnodeops);
        KASSERT(uobj->uo_npages == 0);
        KASSERT(TAILQ_FIRST(&uobj->memq) == NULL);
        vp->v_size = vp->v_writesize = VSIZENOTSET;

        if (mp != NULL) {
                if ((mp->mnt_iflag & IMNT_MPSAFE) != 0)
                        vp->v_vflag |= VV_MPSAFE;
                vfs_unbusy(mp, true, NULL);
        }

        return (0);
}

/*
 * This is really just the reverse of getnewvnode(). Needed for
 * VFS_VGET functions who may need to push back a vnode in case
 * of a locking race.
 */
void
ungetnewvnode(vnode_t *vp)
{

        KASSERT(vp->v_usecount == 1);
        KASSERT(vp->v_data == NULL);
        KASSERT(vp->v_freelisthd == NULL);

        mutex_enter(&vp->v_interlock);
        vp->v_iflag |= VI_CLEAN;
        vrelel(vp, 0);
}

/*
 * Allocate a new, uninitialized vnode.  If 'mp' is non-NULL, this is a
 * marker vnode and we are prepared to wait for the allocation.
 */
vnode_t *
vnalloc(struct mount *mp)
{
        vnode_t *vp;

        vp = pool_cache_get(vnode_cache, (mp != NULL ? PR_WAITOK : PR_NOWAIT));
        if (vp == NULL) {
                return NULL;
        }

        memset(vp, 0, sizeof(*vp));
        UVM_OBJ_INIT(&vp->v_uobj, &uvm_vnodeops, 0);
        cv_init(&vp->v_cv, "vnode");
        /*
         * done by memset() above.
         *      LIST_INIT(&vp->v_nclist);
         *      LIST_INIT(&vp->v_dnclist);
         */

        if (mp != NULL) {
                vp->v_mount = mp;
                vp->v_type = VBAD;
                vp->v_iflag = VI_MARKER;
        } else {
                rw_init(&vp->v_lock.vl_lock);
        }

        return vp;
}

/*
 * Free an unused, unreferenced vnode.
 */
void
vnfree(vnode_t *vp)
{

        KASSERT(vp->v_usecount == 0);

        if ((vp->v_iflag & VI_MARKER) == 0) {
                rw_destroy(&vp->v_lock.vl_lock);
                mutex_enter(&vnode_free_list_lock);
                numvnodes--;
                mutex_exit(&vnode_free_list_lock);
        }

        UVM_OBJ_DESTROY(&vp->v_uobj);
        cv_destroy(&vp->v_cv);
        pool_cache_put(vnode_cache, vp);
}

/*
 * Remove a vnode from its freelist.
 */
static inline void
vremfree(vnode_t *vp)
{

        KASSERT(mutex_owned(&vp->v_interlock));
        KASSERT(vp->v_usecount == 0);

        /*
         * Note that the reference count must not change until
         * the vnode is removed.
         */
        mutex_enter(&vnode_free_list_lock);
        if (vp->v_holdcnt > 0) {
                KASSERT(vp->v_freelisthd == &vnode_hold_list);
        } else {
                KASSERT(vp->v_freelisthd == &vnode_free_list);
        }
        TAILQ_REMOVE(vp->v_freelisthd, vp, v_freelist);
        vp->v_freelisthd = NULL;
        mutex_exit(&vnode_free_list_lock);
}

/*
 * Move a vnode from one mount queue to another.
 */
static void
insmntque(vnode_t *vp, struct mount *mp)
{
        struct mount *omp;

#ifdef DIAGNOSTIC
        if ((mp != NULL) &&
            (mp->mnt_iflag & IMNT_UNMOUNT) &&
            vp->v_tag != VT_VFS) {
                panic("insmntque into dying filesystem");
        }
#endif

        mutex_enter(&mntvnode_lock);
        /*
         * Delete from old mount point vnode list, if on one.
         */
        if ((omp = 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.  The caller must take a reference on the mount
         * structure and donate to the vnode.
         */
        if ((vp->v_mount = mp) != NULL)
                TAILQ_INSERT_TAIL(&mp->mnt_vnodelist, vp, v_mntvnodes);
        mutex_exit(&mntvnode_lock);

        if (omp != NULL) {
                /* Release reference to old mount. */
                vfs_destroy(omp);
        }
}

/*
 * Wait for a vnode (typically with VI_XLOCK set) to be cleaned or
 * recycled.
 */
void
vwait(vnode_t *vp, int flags)
{

        KASSERT(mutex_owned(&vp->v_interlock));
        KASSERT(vp->v_usecount != 0);

        while ((vp->v_iflag & flags) != 0)
                cv_wait(&vp->v_cv, &vp->v_interlock);
}

/*
 * Insert a marker vnode into a mount's vnode list, after the
 * specified vnode.  mntvnode_lock must be held.
 */
void
vmark(vnode_t *mvp, vnode_t *vp)
{
        struct mount *mp;

        mp = mvp->v_mount;

        KASSERT(mutex_owned(&mntvnode_lock));
        KASSERT((mvp->v_iflag & VI_MARKER) != 0);
        KASSERT(vp->v_mount == mp);

        TAILQ_INSERT_AFTER(&mp->mnt_vnodelist, vp, mvp, v_mntvnodes);
}

/*
 * Remove a marker vnode from a mount's vnode list, and return
 * a pointer to the next vnode in the list.  mntvnode_lock must
 * be held.
 */
vnode_t *
vunmark(vnode_t *mvp)
{
        vnode_t *vp;
        struct mount *mp;

        mp = mvp->v_mount;

        KASSERT(mutex_owned(&mntvnode_lock));
        KASSERT((mvp->v_iflag & VI_MARKER) != 0);

        vp = TAILQ_NEXT(mvp, v_mntvnodes);
        TAILQ_REMOVE(&mp->mnt_vnodelist, mvp, v_mntvnodes); 

        KASSERT(vp == NULL || vp->v_mount == mp);

        return vp;
}

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

        if ((vp = bp->b_vp) == NULL)
                return;

        KASSERT(bp->b_objlock == &vp->v_interlock);
        KASSERT(mutex_owned(bp->b_objlock));

        if (--vp->v_numoutput < 0)
                panic("vwakeup: neg numoutput, vp %p", vp);
        if (vp->v_numoutput == 0)
                cv_broadcast(&vp->v_cv);
}

/*
 * Flush out and invalidate all buffers associated with a vnode.
 * Called with the underlying vnode locked, which should prevent new dirty
 * buffers from being queued.
 */
int
vinvalbuf(struct vnode *vp, int flags, kauth_cred_t cred, struct lwp *l,
          bool catch, int slptimeo)
{
        struct buf *bp, *nbp;
        int error;
        int flushflags = PGO_ALLPAGES | PGO_FREE | PGO_SYNCIO |
            (flags & V_SAVE ? PGO_CLEANIT | PGO_RECLAIM : 0);

        /* XXXUBC this doesn't look at flags or slp* */
        mutex_enter(&vp->v_interlock);
        error = VOP_PUTPAGES(vp, 0, 0, flushflags);
        if (error) {
                return error;
        }

        if (flags & V_SAVE) {
                error = VOP_FSYNC(vp, cred, FSYNC_WAIT|FSYNC_RECLAIM, 0, 0);
                if (error)
                        return (error);
                KASSERT(LIST_EMPTY(&vp->v_dirtyblkhd));
        }

        mutex_enter(&bufcache_lock);
restart:
        for (bp = LIST_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
                nbp = LIST_NEXT(bp, b_vnbufs);
                error = bbusy(bp, catch, slptimeo, NULL);
                if (error != 0) {
                        if (error == EPASSTHROUGH)
                                goto restart;
                        mutex_exit(&bufcache_lock);
                        return (error);
                }
                brelsel(bp, BC_INVAL | BC_VFLUSH);
        }

        for (bp = LIST_FIRST(&vp->v_cleanblkhd); bp; bp = nbp) {
                nbp = LIST_NEXT(bp, b_vnbufs);
                error = bbusy(bp, catch, slptimeo, NULL);
                if (error != 0) {
                        if (error == EPASSTHROUGH)
                                goto restart;
                        mutex_exit(&bufcache_lock);
                        return (error);
                }
                /*
                 * 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_oflags & BO_DELWRI) && (flags & V_SAVE)) {
#ifdef DEBUG
                        printf("buffer still DELWRI\n");
#endif
                        bp->b_cflags |= BC_BUSY | BC_VFLUSH;
                        mutex_exit(&bufcache_lock);
                        VOP_BWRITE(bp);
                        mutex_enter(&bufcache_lock);
                        goto restart;
                }
                brelsel(bp, BC_INVAL | BC_VFLUSH);
        }

#ifdef DIAGNOSTIC
        if (!LIST_EMPTY(&vp->v_cleanblkhd) || !LIST_EMPTY(&vp->v_dirtyblkhd))
                panic("vinvalbuf: flush failed, vp %p", vp);
#endif

        mutex_exit(&bufcache_lock);

        return (0);
}

/*
 * Destroy any in core blocks past the truncation length.
 * Called with the underlying vnode locked, which should prevent new dirty
 * buffers from being queued.
 */
int
vtruncbuf(struct vnode *vp, daddr_t lbn, bool catch, int slptimeo)
{
        struct buf *bp, *nbp;
        int error;
        voff_t off;

        off = round_page((voff_t)lbn << vp->v_mount->mnt_fs_bshift);
        mutex_enter(&vp->v_interlock);
        error = VOP_PUTPAGES(vp, off, 0, PGO_FREE | PGO_SYNCIO);
        if (error) {
                return error;
        }

        mutex_enter(&bufcache_lock);
restart:
        for (bp = LIST_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
                nbp = LIST_NEXT(bp, b_vnbufs);
                if (bp->b_lblkno < lbn)
                        continue;
                error = bbusy(bp, catch, slptimeo, NULL);
                if (error != 0) {
                        if (error == EPASSTHROUGH)
                                goto restart;
                        mutex_exit(&bufcache_lock);
                        return (error);
                }
                brelsel(bp, BC_INVAL | BC_VFLUSH);
        }

        for (bp = LIST_FIRST(&vp->v_cleanblkhd); bp; bp = nbp) {
                nbp = LIST_NEXT(bp, b_vnbufs);
                if (bp->b_lblkno < lbn)
                        continue;
                error = bbusy(bp, catch, slptimeo, NULL);
                if (error != 0) {
                        if (error == EPASSTHROUGH)
                                goto restart;
                        mutex_exit(&bufcache_lock);
                        return (error);
                }
                brelsel(bp, BC_INVAL | BC_VFLUSH);
        }
        mutex_exit(&bufcache_lock);

        return (0);
}

/*
 * Flush all dirty buffers from a vnode.
 * Called with the underlying vnode locked, which should prevent new dirty
 * buffers from being queued.
 */
void
vflushbuf(struct vnode *vp, int sync)
{
        struct buf *bp, *nbp;
        int flags = PGO_CLEANIT | PGO_ALLPAGES | (sync ? PGO_SYNCIO : 0);
        bool dirty;

        mutex_enter(&vp->v_interlock);
        (void) VOP_PUTPAGES(vp, 0, 0, flags);

loop:
        mutex_enter(&bufcache_lock);
        for (bp = LIST_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {
                nbp = LIST_NEXT(bp, b_vnbufs);
                if ((bp->b_cflags & BC_BUSY))
                        continue;
                if ((bp->b_oflags & BO_DELWRI) == 0)
                        panic("vflushbuf: not dirty, bp %p", bp);
                bp->b_cflags |= BC_BUSY | BC_VFLUSH;
                mutex_exit(&bufcache_lock);
                /*
                 * 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;
        }
        mutex_exit(&bufcache_lock);

        if (sync == 0)
                return;

        mutex_enter(&vp->v_interlock);
        while (vp->v_numoutput != 0)
                cv_wait(&vp->v_cv, &vp->v_interlock);
        dirty = !LIST_EMPTY(&vp->v_dirtyblkhd);
        mutex_exit(&vp->v_interlock);

        if (dirty) {
                vprint("vflushbuf: dirty", vp);
                goto loop;
        }
}

/*
 * Create a vnode for a block device.
 * Used for root filesystem and swap areas.
 * Also used for memory file system special devices.
 */
int
bdevvp(dev_t dev, vnode_t **vpp)
{

        return (getdevvp(dev, vpp, VBLK));
}

/*
 * Create a vnode for a character device.
 * Used for kernfs and some console handling.
 */
int
cdevvp(dev_t dev, vnode_t **vpp)
{

        return (getdevvp(dev, vpp, VCHR));
}

/*
 * Associate a buffer with a vnode.  There must already be a hold on
 * the vnode.
 */
void
bgetvp(struct vnode *vp, struct buf *bp)
{

        KASSERT(bp->b_vp == NULL);
        KASSERT(bp->b_objlock == &buffer_lock);
        KASSERT(mutex_owned(&vp->v_interlock));
        KASSERT(mutex_owned(&bufcache_lock));
        KASSERT((bp->b_cflags & BC_BUSY) != 0);
        KASSERT(!cv_has_waiters(&bp->b_done));

        vholdl(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);
        bp->b_objlock = &vp->v_interlock;
}

/*
 * Disassociate a buffer from a vnode.
 */
void
brelvp(struct buf *bp)
{
        struct vnode *vp = bp->b_vp;

        KASSERT(vp != NULL);
        KASSERT(bp->b_objlock == &vp->v_interlock);
        KASSERT(mutex_owned(&vp->v_interlock));
        KASSERT(mutex_owned(&bufcache_lock));
        KASSERT((bp->b_cflags & BC_BUSY) != 0);
        KASSERT(!cv_has_waiters(&bp->b_done));

        /*
         * Delete from old vnode list, if on one.
         */
        if (LIST_NEXT(bp, b_vnbufs) != NOLIST)
                bufremvn(bp);

        if (TAILQ_EMPTY(&vp->v_uobj.memq) && (vp->v_iflag & VI_ONWORKLST) &&
            LIST_FIRST(&vp->v_dirtyblkhd) == NULL) {
                vp->v_iflag &= ~VI_WRMAPDIRTY;
                vn_syncer_remove_from_worklist(vp);
        }

        bp->b_objlock = &buffer_lock;
        bp->b_vp = NULL;
        holdrelel(vp);
}

/*
 * Reassign a buffer from one vnode list to another.
 * The list reassignment must be within the same vnode.
 * Used to assign file specific control information
 * (indirect blocks) to the list to which they belong.
 */
void
reassignbuf(struct buf *bp, struct vnode *vp)
{
        struct buflists *listheadp;
        int delayx;

        KASSERT(mutex_owned(&bufcache_lock));
        KASSERT(bp->b_objlock == &vp->v_interlock);
        KASSERT(mutex_owned(&vp->v_interlock));
        KASSERT((bp->b_cflags & BC_BUSY) != 0);

        /*
         * 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_oflags & BO_DELWRI) == 0) {
                listheadp = &vp->v_cleanblkhd;
                if (TAILQ_EMPTY(&vp->v_uobj.memq) &&
                    (vp->v_iflag & VI_ONWORKLST) &&
                    LIST_FIRST(&vp->v_dirtyblkhd) == NULL) {
                        vp->v_iflag &= ~VI_WRMAPDIRTY;
                        vn_syncer_remove_from_worklist(vp);
                }
        } else {
                listheadp = &vp->v_dirtyblkhd;
                if ((vp->v_iflag & VI_ONWORKLST) == 0) {
                        switch (vp->v_type) {
                        case VDIR:
                                delayx = dirdelay;
                                break;
                        case VBLK:
                                if (vp->v_specmountpoint != NULL) {
                                        delayx = metadelay;
                                        break;
                                }
                                /* fall through */
                        default:
                                delayx = filedelay;
                                break;
                        }
                        if (!vp->v_mount ||
                            (vp->v_mount->mnt_flag & MNT_ASYNC) == 0)
                                vn_syncer_add_to_worklist(vp, delayx);
                }
        }
        bufinsvn(bp, listheadp);
}

/*
 * Create a vnode for a device.
 * Used by bdevvp (block device) for root file system etc.,
 * and by cdevvp (character device) for console and kernfs.
 */
static int
getdevvp(dev_t dev, vnode_t **vpp, enum vtype type)
{
        vnode_t *vp;
        vnode_t *nvp;
        int error;

        if (dev == NODEV) {
                *vpp = NULL;
                return (0);
        }
        error = getnewvnode(VT_NON, NULL, spec_vnodeop_p, &nvp);
        if (error) {
                *vpp = NULL;
                return (error);
        }
        vp = nvp;
        vp->v_type = type;
        vp->v_vflag |= VV_MPSAFE;
        uvm_vnp_setsize(vp, 0);
        spec_node_init(vp, dev);
        *vpp = vp;
        return (0);
}

/*
 * Try to gain a reference to a vnode, without acquiring its interlock.
 * The caller must hold a lock that will prevent the vnode from being
 * recycled or freed.
 */
bool
vtryget(vnode_t *vp)
{
        u_int use, next;

        /*
         * If the vnode is being freed, don't make life any harder
         * for vclean() by adding another reference without waiting.
         * This is not strictly necessary, but we'll do it anyway.
         */
        if (__predict_false((vp->v_iflag & (VI_XLOCK | VI_FREEING)) != 0)) {
                return false;
        }
        for (use = vp->v_usecount;; use = next) {
                if (use == 0 || __predict_false((use & VC_XLOCK) != 0)) {
                        /* Need interlock held if first reference. */
                        return false;
                }
                next = atomic_cas_uint(&vp->v_usecount, use, use + 1);
                if (__predict_true(next == use)) {
                        return true;
                }
        }
}

/*
 * Grab a particular vnode from the free list, increment its
 * reference count and lock it. If the vnode lock bit is set the
 * vnode is being eliminated in vgone. In that case, we can not
 * grab the vnode, so the process is awakened when the transition is
 * completed, and an error returned to indicate that the vnode is no
 * longer usable (possibly having been changed to a new file system type).
 */
int
vget(vnode_t *vp, int flags)
{
        int error;

        KASSERT((vp->v_iflag & VI_MARKER) == 0);

        if ((flags & LK_INTERLOCK) == 0)
                mutex_enter(&vp->v_interlock);

        /*
         * Before adding a reference, we must remove the vnode
         * from its freelist.
         */
        if (vp->v_usecount == 0) {
                vremfree(vp);
                vp->v_usecount = 1;
        } else {
                atomic_inc_uint(&vp->v_usecount);
        }

        /*
         * 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 if
         * the VI_XLOCK or VI_FREEING flags are set.
         */
        if ((vp->v_iflag & (VI_XLOCK | VI_FREEING)) != 0) {
                if ((flags & LK_NOWAIT) != 0) {
                        vrelel(vp, 0);
                        return EBUSY;
                }
                vwait(vp, VI_XLOCK | VI_FREEING);
                vrelel(vp, 0);
                return ENOENT;
        }

        if ((vp->v_iflag & VI_INACTNOW) != 0) {
                /*
                 * if it's being desactived, wait for it to complete.
                 * Make sure to not return a clean vnode.
                 */
                 if ((flags & LK_NOWAIT) != 0) {
                        vrelel(vp, 0);
                        return EBUSY;
                }
                vwait(vp, VI_INACTNOW);
                if ((vp->v_iflag & VI_CLEAN) != 0) {
                        vrelel(vp, 0);
                        return ENOENT;
                }
        }
        if (flags & LK_TYPE_MASK) {
                error = vn_lock(vp, flags | LK_INTERLOCK);
                if (error != 0) {
                        vrele(vp);
                }
                return error;
        }
        mutex_exit(&vp->v_interlock);
        return 0;
}

/*
 * vput(), just unlock and vrele()
 */
void
vput(vnode_t *vp)
{

        KASSERT((vp->v_iflag & VI_MARKER) == 0);

        VOP_UNLOCK(vp, 0);
        vrele(vp);
}

/*
 * Try to drop reference on a vnode.  Abort if we are releasing the
 * last reference.  Note: this _must_ succeed if not the last reference.
 */
static inline bool
vtryrele(vnode_t *vp)
{
        u_int use, next;

        for (use = vp->v_usecount;; use = next) {
                if (use == 1) {
                        return false;
                }
                KASSERT((use & VC_MASK) > 1);
                next = atomic_cas_uint(&vp->v_usecount, use, use - 1);
                if (__predict_true(next == use)) {
                        return true;
                }
        }
}

/*
 * Vnode release.  If reference count drops to zero, call inactive
 * routine and either return to freelist or free to the pool.
 */
void
vrelel(vnode_t *vp, int flags)
{
        bool recycle, defer;
        int error;

        KASSERT(mutex_owned(&vp->v_interlock));
        KASSERT((vp->v_iflag & VI_MARKER) == 0);
        KASSERT(vp->v_freelisthd == NULL);

        if (__predict_false(vp->v_op == dead_vnodeop_p &&
            (vp->v_iflag & (VI_CLEAN|VI_XLOCK)) == 0)) {
                vpanic(vp, "dead but not clean");
        }

        /*
         * If not the last reference, just drop the reference count
         * and unlock.
         */
        if (vtryrele(vp)) {
                vp->v_iflag |= VI_INACTREDO;
                mutex_exit(&vp->v_interlock);
                return;
        }
        if (vp->v_usecount <= 0 || vp->v_writecount != 0) {
                vpanic(vp, "vrelel: bad ref count");
        }

        KASSERT((vp->v_iflag & VI_XLOCK) == 0);

        /*
         * If not clean, deactivate the vnode, but preserve
         * our reference across the call to VOP_INACTIVE().
         */
 retry:
        if ((vp->v_iflag & VI_CLEAN) == 0) {
                recycle = false;
                vp->v_iflag |= VI_INACTNOW;

                /*
                 * XXX This ugly block can be largely eliminated if
                 * locking is pushed down into the file systems.
                 */
                if (curlwp == uvm.pagedaemon_lwp) {
                        /* The pagedaemon can't wait around; defer. */
                        defer = true;
                } else if (curlwp == vrele_lwp) {
                        /*
                         * We have to try harder. But we can't sleep
                         * with VI_INACTNOW as vget() may be waiting on it.
                         */
                        vp->v_iflag &= ~(VI_INACTREDO|VI_INACTNOW);
                        cv_broadcast(&vp->v_cv);
                        error = vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK |
                            LK_RETRY);
                        if (error != 0) {
                                /* XXX */
                                vpanic(vp, "vrele: unable to lock %p");
                        }
                        mutex_enter(&vp->v_interlock);
                        /*
                         * if we did get another reference while
                         * sleeping, don't try to inactivate it yet.
                         */
                        if (__predict_false(vtryrele(vp))) {
                                VOP_UNLOCK(vp, 0);
                                mutex_exit(&vp->v_interlock);
                                return;
                        }
                        vp->v_iflag |= VI_INACTNOW;
                        mutex_exit(&vp->v_interlock);
                        defer = false;
                } else if ((vp->v_iflag & VI_LAYER) != 0) {
                        /* 
                         * Acquiring the stack's lock in vclean() even
                         * for an honest vput/vrele is dangerous because
                         * our caller may hold other vnode locks; defer.
                         */
                        defer = true;
                } else {                
                        /* If we can't acquire the lock, then defer. */
                        vp->v_iflag &= ~VI_INACTREDO;
                        error = vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK |
                            LK_NOWAIT);
                        if (error != 0) {
                                defer = true;
                                mutex_enter(&vp->v_interlock);
                        } else {
                                defer = false;
                        }
                }

                if (defer) {
                        /*
                         * Defer reclaim to the kthread; it's not safe to
                         * clean it here.  We donate it our last reference.
                         */
                        KASSERT(mutex_owned(&vp->v_interlock));
                        KASSERT((vp->v_iflag & VI_INACTPEND) == 0);
                        vp->v_iflag &= ~VI_INACTNOW;
                        vp->v_iflag |= VI_INACTPEND;
                        mutex_enter(&vrele_lock);
                        TAILQ_INSERT_TAIL(&vrele_list, vp, v_freelist);
                        if (++vrele_pending > (desiredvnodes >> 8))
                                cv_signal(&vrele_cv); 
                        mutex_exit(&vrele_lock);
                        cv_broadcast(&vp->v_cv);
                        mutex_exit(&vp->v_interlock);
                        return;
                }

#ifdef DIAGNOSTIC
                if ((vp->v_type == VBLK || vp->v_type == VCHR) &&
                    vp->v_specnode != NULL && vp->v_specnode->sn_opencnt != 0) {
                        vprint("vrelel: missing VOP_CLOSE()", vp);
                }
#endif

                /*
                 * The vnode can gain another reference while being
                 * deactivated.  If VOP_INACTIVE() indicates that
                 * the described file has been deleted, then recycle
                 * the vnode irrespective of additional references.
                 * Another thread may be waiting to re-use the on-disk
                 * inode.
                 *
                 * Note that VOP_INACTIVE() will drop the vnode lock.
                 */
                VOP_INACTIVE(vp, &recycle);
                mutex_enter(&vp->v_interlock);
                vp->v_iflag &= ~VI_INACTNOW;
                cv_broadcast(&vp->v_cv);
                if (!recycle) {
                        if (vtryrele(vp)) {
                                mutex_exit(&vp->v_interlock);
                                return;
                        }

                        /*
                         * If we grew another reference while
                         * VOP_INACTIVE() was underway, retry.
                         */
                        if ((vp->v_iflag & VI_INACTREDO) != 0) {
                                goto retry;
                        }
                }

                /* Take care of space accounting. */
                if (vp->v_iflag & VI_EXECMAP) {
                        atomic_add_int(&uvmexp.execpages,
                            -vp->v_uobj.uo_npages);
                        atomic_add_int(&uvmexp.filepages,
                            vp->v_uobj.uo_npages);
                }
                vp->v_iflag &= ~(VI_TEXT|VI_EXECMAP|VI_WRMAP);
                vp->v_vflag &= ~VV_MAPPED;

                /*
                 * Recycle the vnode if the file is now unused (unlinked),
                 * otherwise just free it.
                 */
                if (recycle) {
                        vclean(vp, DOCLOSE);
                }
                KASSERT(vp->v_usecount > 0);
        }

        if (atomic_dec_uint_nv(&vp->v_usecount) != 0) {
                /* Gained another reference while being reclaimed. */
                mutex_exit(&vp->v_interlock);
                return;
        }

        if ((vp->v_iflag & VI_CLEAN) != 0) {
                /*
                 * It's clean so destroy it.  It isn't referenced
                 * anywhere since it has been reclaimed.
                 */
                KASSERT(vp->v_holdcnt == 0);
                KASSERT(vp->v_writecount == 0);
                mutex_exit(&vp->v_interlock);
                insmntque(vp, NULL);
                if (vp->v_type == VBLK || vp->v_type == VCHR) {
                        spec_node_destroy(vp);
                }
                vnfree(vp);
        } else {
                /*
                 * Otherwise, put it back onto the freelist.  It
                 * can't be destroyed while still associated with
                 * a file system.
                 */
                mutex_enter(&vnode_free_list_lock);
                if (vp->v_holdcnt > 0) {
                        vp->v_freelisthd = &vnode_hold_list;
                } else {
                        vp->v_freelisthd = &vnode_free_list;
                }
                TAILQ_INSERT_TAIL(vp->v_freelisthd, vp, v_freelist);
                mutex_exit(&vnode_free_list_lock);
                mutex_exit(&vp->v_interlock);
        }
}

void
vrele(vnode_t *vp)
{

        KASSERT((vp->v_iflag & VI_MARKER) == 0);

        if ((vp->v_iflag & VI_INACTNOW) == 0 && vtryrele(vp)) {
                return;
        }
        mutex_enter(&vp->v_interlock);
        vrelel(vp, 0);
}

static void
vrele_thread(void *cookie)
{
        vnode_t *vp;

        for (;;) {
                mutex_enter(&vrele_lock);
                while (TAILQ_EMPTY(&vrele_list)) {
                        vrele_gen++;
                        cv_broadcast(&vrele_cv);
                        cv_timedwait(&vrele_cv, &vrele_lock, hz);
                }
                vp = TAILQ_FIRST(&vrele_list);
                TAILQ_REMOVE(&vrele_list, vp, v_freelist);
                vrele_pending--;
                mutex_exit(&vrele_lock);

                /*
                 * If not the last reference, then ignore the vnode
                 * and look for more work.
                 */
                mutex_enter(&vp->v_interlock);
                KASSERT((vp->v_iflag & VI_INACTPEND) != 0);
                vp->v_iflag &= ~VI_INACTPEND;
                vrelel(vp, 0);
        }
}

/*
 * Page or buffer structure gets a reference.
 * Called with v_interlock held.
 */
void
vholdl(vnode_t *vp)
{

        KASSERT(mutex_owned(&vp->v_interlock));
        KASSERT((vp->v_iflag & VI_MARKER) == 0);

        if (vp->v_holdcnt++ == 0 && vp->v_usecount == 0) {
                mutex_enter(&vnode_free_list_lock);
                KASSERT(vp->v_freelisthd == &vnode_free_list);
                TAILQ_REMOVE(vp->v_freelisthd, vp, v_freelist);
                vp->v_freelisthd = &vnode_hold_list;
                TAILQ_INSERT_TAIL(vp->v_freelisthd, vp, v_freelist);
                mutex_exit(&vnode_free_list_lock);
        }
}

/*
 * Page or buffer structure frees a reference.
 * Called with v_interlock held.
 */
void
holdrelel(vnode_t *vp)
{

        KASSERT(mutex_owned(&vp->v_interlock));
        KASSERT((vp->v_iflag & VI_MARKER) == 0);

        if (vp->v_holdcnt <= 0) {
                vpanic(vp, "holdrelel: holdcnt vp %p");
        }

        vp->v_holdcnt--;
        if (vp->v_holdcnt == 0 && vp->v_usecount == 0) {
                mutex_enter(&vnode_free_list_lock);
                KASSERT(vp->v_freelisthd == &vnode_hold_list);
                TAILQ_REMOVE(vp->v_freelisthd, vp, v_freelist);
                vp->v_freelisthd = &vnode_free_list;
                TAILQ_INSERT_TAIL(vp->v_freelisthd, vp, v_freelist);
                mutex_exit(&vnode_free_list_lock);
        }
}

/*
 * Vnode reference, where a reference is already held by some other
 * object (for example, a file structure).
 */
void
vref(vnode_t *vp)
{

        KASSERT((vp->v_iflag & VI_MARKER) == 0);
        KASSERT(vp->v_usecount != 0);

        atomic_inc_uint(&vp->v_usecount);
}

/*
 * Remove any vnodes in the vnode table belonging to mount point mp.
 *
 * If FORCECLOSE is not specified, there should not be any active ones,
 * return error if any are found (nb: this is a user error, not a
 * system error). If FORCECLOSE is specified, detach any active vnodes
 * that are found.
 *
 * If WRITECLOSE is set, only flush out regular file vnodes open for
 * writing.
 *
 * SKIPSYSTEM causes any vnodes marked V_SYSTEM to be skipped.
 */
#ifdef DEBUG
int busyprt = 0;        /* print out busy vnodes */
struct ctldebug debug1 = { "busyprt", &busyprt };
#endif

static vnode_t *
vflushnext(vnode_t *mvp, int *when)
{

        if (hardclock_ticks > *when) {
                mutex_exit(&mntvnode_lock);
                yield();
                mutex_enter(&mntvnode_lock);
                *when = hardclock_ticks + hz / 10;
        }

        return vunmark(mvp);
}

int
vflush(struct mount *mp, vnode_t *skipvp, int flags)
{
        vnode_t *vp, *mvp;
        int busy = 0, when = 0, gen;

        /*
         * First, flush out any vnode references from vrele_list.
         */
        mutex_enter(&vrele_lock);
        gen = vrele_gen;
        while (vrele_pending && gen == vrele_gen) {
                cv_broadcast(&vrele_cv);
                cv_wait(&vrele_cv, &vrele_lock);
        }
        mutex_exit(&vrele_lock);

        /* Allocate a marker vnode. */
        if ((mvp = vnalloc(mp)) == NULL)
                return (ENOMEM);

        /*
         * NOTE: not using the TAILQ_FOREACH here since in this loop vgone()
         * and vclean() are called
         */
        mutex_enter(&mntvnode_lock);
        for (vp = TAILQ_FIRST(&mp->mnt_vnodelist); vp != NULL;
            vp = vflushnext(mvp, &when)) {
                vmark(mvp, vp);
                if (vp->v_mount != mp || vismarker(vp))
                        continue;
                /*
                 * Skip over a selected vnode.
                 */
                if (vp == skipvp)
                        continue;
                mutex_enter(&vp->v_interlock);
                /*
                 * Ignore clean but still referenced vnodes.
                 */
                if ((vp->v_iflag & VI_CLEAN) != 0) {
                        mutex_exit(&vp->v_interlock);
                        continue;
                }
                /*
                 * Skip over a vnodes marked VSYSTEM.
                 */
                if ((flags & SKIPSYSTEM) && (vp->v_vflag & VV_SYSTEM)) {
                        mutex_exit(&vp->v_interlock);
                        continue;
                }
                /*
                 * If WRITECLOSE is set, only flush out regular file
                 * vnodes open for writing.
                 */
                if ((flags & WRITECLOSE) &&
                    (vp->v_writecount == 0 || vp->v_type != VREG)) {
                        mutex_exit(&vp->v_interlock);
                        continue;
                }
                /*
                 * With v_usecount == 0, all we need to do is clear
                 * out the vnode data structures and we are done.
                 */
                if (vp->v_usecount == 0) {
                        mutex_exit(&mntvnode_lock);
                        vremfree(vp);
                        vp->v_usecount = 1;
                        vclean(vp, DOCLOSE);
                        vrelel(vp, 0);
                        mutex_enter(&mntvnode_lock);
                        continue;
                }
                /*
                 * If FORCECLOSE is set, forcibly close the vnode.
                 * For block or character devices, revert to an
                 * anonymous device.  For all other files, just
                 * kill them.
                 */
                if (flags & FORCECLOSE) {
                        mutex_exit(&mntvnode_lock);
                        atomic_inc_uint(&vp->v_usecount);
                        if (vp->v_type != VBLK && vp->v_type != VCHR) {
                                vclean(vp, DOCLOSE);
                                vrelel(vp, 0);
                        } else {
                                vclean(vp, 0);
                                vp->v_op = spec_vnodeop_p; /* XXXSMP */
                                mutex_exit(&vp->v_interlock);
                                /*
                                 * The vnode isn't clean, but still resides
                                 * on the mount list.  Remove it. XXX This
                                 * is a bit dodgy.
                                 */
                                insmntque(vp, NULL);
                                vrele(vp);
                        }
                        mutex_enter(&mntvnode_lock);
                        continue;
                }
#ifdef DEBUG
                if (busyprt)
                        vprint("vflush: busy vnode", vp);
#endif
                mutex_exit(&vp->v_interlock);
                busy++;
        }
        mutex_exit(&mntvnode_lock);
        vnfree(mvp);
        if (busy)
                return (EBUSY);
        return (0);
}

/*
 * Disassociate the underlying file system from a vnode.
 *
 * Must be called with the interlock held, and will return with it held.
 */
void
vclean(vnode_t *vp, int flags)
{
        lwp_t *l = curlwp;
        bool recycle, active;
        int error;

        KASSERT(mutex_owned(&vp->v_interlock));
        KASSERT((vp->v_iflag & VI_MARKER) == 0);
        KASSERT(vp->v_usecount != 0);

        /* If cleaning is already in progress wait until done and return. */
        if (vp->v_iflag & VI_XLOCK) {
                vwait(vp, VI_XLOCK);
                return;
        }

        /* If already clean, nothing to do. */
        if ((vp->v_iflag & VI_CLEAN) != 0) {
                return;
        }

        /*
         * Prevent the vnode from being recycled or brought into use
         * while we clean it out.
         */
        vp->v_iflag |= VI_XLOCK;
        if (vp->v_iflag & VI_EXECMAP) {
                atomic_add_int(&uvmexp.execpages, -vp->v_uobj.uo_npages);
                atomic_add_int(&uvmexp.filepages, vp->v_uobj.uo_npages);
        }
        vp->v_iflag &= ~(VI_TEXT|VI_EXECMAP);
        active = (vp->v_usecount > 1);

        /* XXXAD should not lock vnode under layer */
        VOP_LOCK(vp, LK_EXCLUSIVE | LK_INTERLOCK);

        /*
         * Clean out any cached data associated with the vnode.
         * If purging an active vnode, it must be closed and
         * deactivated before being reclaimed. Note that the
         * VOP_INACTIVE will unlock the vnode.
         */
        if (flags & DOCLOSE) {
                error = vinvalbuf(vp, V_SAVE, NOCRED, l, 0, 0);
                if (error != 0) {
                        /* XXX, fix vn_start_write's grab of mp and use that. */

                        if (wapbl_vphaswapbl(vp))
                                WAPBL_DISCARD(wapbl_vptomp(vp));
                        error = vinvalbuf(vp, 0, NOCRED, l, 0, 0);
                }
                KASSERT(error == 0);
                KASSERT((vp->v_iflag & VI_ONWORKLST) == 0);
                if (active && (vp->v_type == VBLK || vp->v_type == VCHR)) {
                         spec_node_revoke(vp);
                }
        }
        if (active) {
                VOP_INACTIVE(vp, &recycle);
        } else {
                /*
                 * Any other processes trying to obtain this lock must first
                 * wait for VI_XLOCK to clear, then call the new lock operation.
                 */
                VOP_UNLOCK(vp, 0);
        }

        /* Disassociate the underlying file system from the vnode. */
        if (VOP_RECLAIM(vp)) {
                vpanic(vp, "vclean: cannot reclaim");
        }

        KASSERT(vp->v_uobj.uo_npages == 0);
        if (vp->v_type == VREG && vp->v_ractx != NULL) {
                uvm_ra_freectx(vp->v_ractx);
                vp->v_ractx = NULL;
        }
        cache_purge(vp);

        /* Done with purge, notify sleepers of the grim news. */
        mutex_enter(&vp->v_interlock);
        vp->v_op = dead_vnodeop_p;
        vp->v_tag = VT_NON;
        vp->v_vnlock = &vp->v_lock;
        KNOTE(&vp->v_klist, NOTE_REVOKE);
        vp->v_iflag &= ~(VI_XLOCK | VI_FREEING);
        vp->v_vflag &= ~VV_LOCKSWORK;
        if ((flags & DOCLOSE) != 0) {
                vp->v_iflag |= VI_CLEAN;
        }
        cv_broadcast(&vp->v_cv);

        KASSERT((vp->v_iflag & VI_ONWORKLST) == 0);
}

/*
 * Recycle an unused vnode to the front of the free list.
 * Release the passed interlock if the vnode will be recycled.
 */
int
vrecycle(vnode_t *vp, kmutex_t *inter_lkp, struct lwp *l)
{

        KASSERT((vp->v_iflag & VI_MARKER) == 0);

        mutex_enter(&vp->v_interlock);
        if (vp->v_usecount != 0) {
                mutex_exit(&vp->v_interlock);
                return (0);
        }
        if (inter_lkp)
                mutex_exit(inter_lkp);
        vremfree(vp);
        vp->v_usecount = 1;
        vclean(vp, DOCLOSE);
        vrelel(vp, 0);
        return (1);
}

/*
 * Eliminate all activity associated with a vnode in preparation for
 * reuse.  Drops a reference from the vnode.
 */
void
vgone(vnode_t *vp)
{

        mutex_enter(&vp->v_interlock);
        vclean(vp, DOCLOSE);
        vrelel(vp, 0);
}

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

        mutex_enter(&device_lock);
        for (vp = specfs_hash[SPECHASH(dev)]; vp; vp = vp->v_specnext) {
                if (dev != vp->v_rdev || type != vp->v_type)
                        continue;
                *vpp = vp;
                rc = 1;
                break;
        }
        mutex_exit(&device_lock);
        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)
{
        vnode_t *vp, **vpp;
        dev_t dev;
        int mn;

        vp = NULL;      /* XXX gcc */

        mutex_enter(&device_lock);
        for (mn = minl; mn <= minh; mn++) {
                dev = makedev(maj, mn);
                vpp = &specfs_hash[SPECHASH(dev)];
                for (vp = *vpp; vp != NULL;) {
                        mutex_enter(&vp->v_interlock);
                        if ((vp->v_iflag & VI_CLEAN) != 0 ||
                            dev != vp->v_rdev || type != vp->v_type) {
                                mutex_exit(&vp->v_interlock);
                                vp = vp->v_specnext;
                                continue;
                        }
                        mutex_exit(&device_lock);
                        if (vget(vp, LK_INTERLOCK) == 0) {
                                VOP_REVOKE(vp, REVOKEALL);
                                vrele(vp);
                        }
                        mutex_enter(&device_lock);
                        vp = *vpp;
                }
        }
        mutex_exit(&device_lock);
}

/*
 * Eliminate all activity associated with the requested vnode
 * and with all vnodes aliased to the requested vnode.
 */
void
vrevoke(vnode_t *vp)
{
        vnode_t *vq, **vpp;
        enum vtype type;
        dev_t dev;

        KASSERT(vp->v_usecount > 0);

        mutex_enter(&vp->v_interlock);
        if ((vp->v_iflag & VI_CLEAN) != 0) {
                mutex_exit(&vp->v_interlock);
                return;
        } else if (vp->v_type != VBLK && vp->v_type != VCHR) {
                atomic_inc_uint(&vp->v_usecount);
                vclean(vp, DOCLOSE);
                vrelel(vp, 0);
                return;
        } else {
                dev = vp->v_rdev;
                type = vp->v_type;
                mutex_exit(&vp->v_interlock);
        }

        vpp = &specfs_hash[SPECHASH(dev)];
        mutex_enter(&device_lock);
        for (vq = *vpp; vq != NULL;) {
                /* If clean or being cleaned, then ignore it. */
                mutex_enter(&vq->v_interlock);
                if ((vq->v_iflag & (VI_CLEAN | VI_XLOCK)) != 0 ||
                    vq->v_rdev != dev || vq->v_type != type) {
                        mutex_exit(&vq->v_interlock);
                        vq = vq->v_specnext;
                        continue;
                }
                mutex_exit(&device_lock);
                if (vq->v_usecount == 0) {
                        vremfree(vq);
                        vq->v_usecount = 1;
                } else {
                        atomic_inc_uint(&vq->v_usecount);
                }
                vclean(vq, DOCLOSE);
                vrelel(vq, 0);
                mutex_enter(&device_lock);
                vq = *vpp;
        }
        mutex_exit(&device_lock);
}

/*
 * sysctl helper routine to return list of supported fstypes
 */
int
sysctl_vfs_generic_fstypes(SYSCTLFN_ARGS)
{
        char bf[sizeof(((struct statvfs *)NULL)->f_fstypename)];
        char *where = oldp;
        struct vfsops *v;
        size_t needed, left, slen;
        int error, first;

        if (newp != NULL)
                return (EPERM);
        if (namelen != 0)
                return (EINVAL);

        first = 1;
        error = 0;
        needed = 0;
        left = *oldlenp;

        sysctl_unlock();
        mutex_enter(&vfs_list_lock);
        LIST_FOREACH(v, &vfs_list, vfs_list) {
                if (where == NULL)
                        needed += strlen(v->vfs_name) + 1;
                else {
                        memset(bf, 0, sizeof(bf));
                        if (first) {
                                strncpy(bf, v->vfs_name, sizeof(bf));
                                first = 0;
                        } else {
                                bf[0] = ' ';
                                strncpy(bf + 1, v->vfs_name, sizeof(bf) - 1);
                        }
                        bf[sizeof(bf)-1] = '\0';
                        slen = strlen(bf);
                        if (left < slen + 1)
                                break;
                        v->vfs_refcount++;
                        mutex_exit(&vfs_list_lock);
                        /* +1 to copy out the trailing NUL byte */
                        error = copyout(bf, where, slen + 1);
                        mutex_enter(&vfs_list_lock);
                        v->vfs_refcount--;
                        if (error)
                                break;
                        where += slen;
                        needed += slen;
                        left -= slen;
                }
        }
        mutex_exit(&vfs_list_lock);
        sysctl_relock();
        *oldlenp = needed;
        return (error);
}


int kinfo_vdebug = 1;
int kinfo_vgetfailed;
#define KINFO_VNODESLOP 10
/*
 * Dump vnode list (via sysctl).
 * Copyout address of vnode followed by vnode.
 */
/* ARGSUSED */
int
sysctl_kern_vnode(SYSCTLFN_ARGS)
{
        char *where = oldp;
        size_t *sizep = oldlenp;
        struct mount *mp, *nmp;
        vnode_t *vp, *mvp, vbuf;
        char *bp = where;
        char *ewhere;
        int error;

        if (namelen != 0)
                return (EOPNOTSUPP);
        if (newp != NULL)
                return (EPERM);

#define VPTRSZ  sizeof(vnode_t *)
#define VNODESZ sizeof(vnode_t)
        if (where == NULL) {
                *sizep = (numvnodes + KINFO_VNODESLOP) * (VPTRSZ + VNODESZ);
                return (0);
        }
        ewhere = where + *sizep;

        sysctl_unlock();
        mutex_enter(&mountlist_lock);
        for (mp = CIRCLEQ_FIRST(&mountlist); mp != (void *)&mountlist;
            mp = nmp) {
                if (vfs_busy(mp, &nmp)) {
                        continue;
                }
                /* Allocate a marker vnode. */
                mvp = vnalloc(mp);
                /* Should never fail for mp != NULL */
                KASSERT(mvp != NULL);
                mutex_enter(&mntvnode_lock);
                for (vp = TAILQ_FIRST(&mp->mnt_vnodelist); vp;
                    vp = vunmark(mvp)) {
                        vmark(mvp, vp);
                        /*
                         * Check that the vp is still associated with
                         * this filesystem.  RACE: could have been
                         * recycled onto the same filesystem.
                         */
                        if (vp->v_mount != mp || vismarker(vp))
                                continue;
                        if (bp + VPTRSZ + VNODESZ > ewhere) {
                                (void)vunmark(mvp);
                                mutex_exit(&mntvnode_lock);
                                vnfree(mvp);
                                vfs_unbusy(mp, false, NULL);
                                sysctl_relock();
                                *sizep = bp - where;
                                return (ENOMEM);
                        }
                        memcpy(&vbuf, vp, VNODESZ);
                        mutex_exit(&mntvnode_lock);
                        if ((error = copyout(&vp, bp, VPTRSZ)) ||
                            (error = copyout(&vbuf, bp + VPTRSZ, VNODESZ))) {
                                mutex_enter(&mntvnode_lock);
                                (void)vunmark(mvp);
                                mutex_exit(&mntvnode_lock);
                                vnfree(mvp);
                                vfs_unbusy(mp, false, NULL);
                                sysctl_relock();
                                return (error);
                        }
                        bp += VPTRSZ + VNODESZ;
                        mutex_enter(&mntvnode_lock);
                }
                mutex_exit(&mntvnode_lock);
                vnfree(mvp);
                vfs_unbusy(mp, false, &nmp);
        }
        mutex_exit(&mountlist_lock);
        sysctl_relock();

        *sizep = bp - where;
        return (0);
}

/*
 * Remove clean vnodes from a mountpoint's vnode list.
 */
void
vfs_scrubvnlist(struct mount *mp)
{
        vnode_t *vp, *nvp;

 retry:
        mutex_enter(&mntvnode_lock);
        for (vp = TAILQ_FIRST(&mp->mnt_vnodelist); vp; vp = nvp) {
                nvp = TAILQ_NEXT(vp, v_mntvnodes);
                mutex_enter(&vp->v_interlock);
                if ((vp->v_iflag & VI_CLEAN) != 0) {
                        TAILQ_REMOVE(&mp->mnt_vnodelist, vp, v_mntvnodes);
                        vp->v_mount = NULL;
                        mutex_exit(&mntvnode_lock);
                        mutex_exit(&vp->v_interlock);
                        vfs_destroy(mp);
                        goto retry;
                }
                mutex_exit(&vp->v_interlock);
        }
        mutex_exit(&mntvnode_lock);
}

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

        if (vp->v_type != VBLK)
                return ENOTBLK;
        if (vp->v_specmountpoint != NULL)
                return (EBUSY);
        mutex_enter(&device_lock);
        for (vq = specfs_hash[SPECHASH(vp->v_rdev)]; vq != NULL;
            vq = vq->v_specnext) {
                if (vq->v_rdev != vp->v_rdev || vq->v_type != vp->v_type)
                        continue;
                if (vq->v_specmountpoint != NULL) {
                        error = EBUSY;
                        break;
                }
        }
        mutex_exit(&device_lock);
        return (error);
}

/*
 * Unmount all file systems.
 * We traverse the list in reverse order under the assumption that doing so
 * will avoid needing to worry about dependencies.
 */
bool
vfs_unmountall(struct lwp *l)
{
        printf("unmounting file systems...");
        return vfs_unmountall1(l, true, true);
}

static void
vfs_unmount_print(struct mount *mp, const char *pfx)
{
        printf("%sunmounted %s on %s type %s\n", pfx,
            mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname,
            mp->mnt_stat.f_fstypename);
}

bool
vfs_unmount_forceone(struct lwp *l)
{
        struct mount *mp, *nmp = NULL;
        int error;

        CIRCLEQ_FOREACH_REVERSE(mp, &mountlist, mnt_list) {
                if (nmp == NULL || mp->mnt_gen > nmp->mnt_gen)
                        nmp = mp;
        }

        if (nmp == NULL)
                return false;

#ifdef DEBUG
        printf("\nforcefully unmounting %s (%s)...",
            nmp->mnt_stat.f_mntonname, nmp->mnt_stat.f_mntfromname);
#endif
        atomic_inc_uint(&nmp->mnt_refcnt);
        if ((error = dounmount(nmp, MNT_FORCE, l)) == 0) {
                vfs_unmount_print(nmp, "forcefully ");
                return true;
        } else
                atomic_dec_uint(&nmp->mnt_refcnt);

#ifdef DEBUG
        printf("forceful unmount of %s failed with error %d\n",
            nmp->mnt_stat.f_mntonname, error);
#endif

        return false;
}

bool
vfs_unmountall1(struct lwp *l, bool force, bool verbose)
{
        struct mount *mp, *nmp;
        bool any_error = false, progress = false;
        int error;

        for (mp = CIRCLEQ_LAST(&mountlist);
             mp != (void *)&mountlist;
             mp = nmp) {
                nmp = CIRCLEQ_PREV(mp, mnt_list);
#ifdef DEBUG
                printf("\nunmounting %p %s (%s)...",
                    (void *)mp, mp->mnt_stat.f_mntonname,
                    mp->mnt_stat.f_mntfromname);
#endif
                atomic_inc_uint(&mp->mnt_refcnt);
                if ((error = dounmount(mp, force ? MNT_FORCE : 0, l)) == 0) {
                        vfs_unmount_print(mp, "");
                        progress = true;
                } else {
                        atomic_dec_uint(&mp->mnt_refcnt);
                        if (verbose) {
                                printf("unmount of %s failed with error %d\n",
                                    mp->mnt_stat.f_mntonname, error);
                        }
                        any_error = true;
                }
        }
        if (verbose)
                printf(" done\n");
        if (any_error && verbose)
                printf("WARNING: some file systems would not unmount\n");
        return progress;
}

/*
 * Sync and unmount file systems before shutting down.
 */
void
vfs_shutdown(void)
{
        struct lwp *l;

        /* XXX we're certainly not running in lwp0's context! */
        l = (curlwp == NULL) ? &lwp0 : curlwp;

        vfs_shutdown1(l);
}

void
vfs_sync_all(struct lwp *l)
{
        printf("syncing disks... ");

        /* remove user processes from run queue */
        suspendsched();
        (void) spl0();

        /* avoid coming back this way again if we panic. */
        doing_shutdown = 1;

        sys_sync(l, NULL, NULL);

        /* Wait for sync to finish. */
        if (buf_syncwait() != 0) {
#if defined(DDB) && defined(DEBUG_HALT_BUSY)
                Debugger();
#endif
                printf("giving up\n");
                return;
        } else
                printf("done\n");
}

static void
vfs_shutdown1(struct lwp *l)
{

        vfs_sync_all(l);

        /*
         * If we've panic'd, don't make the situation potentially
         * worse by unmounting the file systems.
         */
        if (panicstr != NULL)
                return;

        /* Release inodes held by texts before update. */
#ifdef notdef
        vnshutdown();
#endif
        /* Unmount file systems. */
        vfs_unmountall(l);
}

/*
 * Print a list of supported file system types (used by vfs_mountroot)
 */
static void
vfs_print_fstypes(void)
{
        struct vfsops *v;
        int cnt = 0;

        mutex_enter(&vfs_list_lock);
        LIST_FOREACH(v, &vfs_list, vfs_list)
                ++cnt;
        mutex_exit(&vfs_list_lock);

        if (cnt == 0) {
                printf("WARNING: No file system modules have been loaded.\n");
                return;
        }

        printf("Supported file systems:");
        mutex_enter(&vfs_list_lock);
        LIST_FOREACH(v, &vfs_list, vfs_list) {
                printf(" %s", v->vfs_name);
        }
        mutex_exit(&vfs_list_lock);
        printf("\n");
}

/*
 * Mount the root file system.  If the operator didn't specify a
 * file system to use, try all possible file systems until one
 * succeeds.
 */
int
vfs_mountroot(void)
{
        struct vfsops *v;
        int error = ENODEV;

        if (root_device == NULL)
                panic("vfs_mountroot: root device unknown");

        switch (device_class(root_device)) {
        case DV_IFNET:
                if (rootdev != NODEV)
                        panic("vfs_mountroot: rootdev set for DV_IFNET "
                            "(0x%llx -> %llu,%llu)",
                            (unsigned long long)rootdev,
                            (unsigned long long)major(rootdev),
                            (unsigned long long)minor(rootdev));
                break;

        case DV_DISK:
                if (rootdev == NODEV)
                        panic("vfs_mountroot: rootdev not set for DV_DISK");
                if (bdevvp(rootdev, &rootvp))
                        panic("vfs_mountroot: can't get vnode for rootdev");
                error = VOP_OPEN(rootvp, FREAD, FSCRED);
                if (error) {
                        printf("vfs_mountroot: can't open root device\n");
                        return (error);
                }
                break;

        case DV_VIRTUAL:
                break;

        default:
                printf("%s: inappropriate for root file system\n",
                    device_xname(root_device));
                return (ENODEV);
        }

        /*
         * If user specified a root fs type, use it.  Make sure the
         * specified type exists and has a mount_root()
         */
        if (strcmp(rootfstype, ROOT_FSTYPE_ANY) != 0) {
                v = vfs_getopsbyname(rootfstype);
                error = EFTYPE;
                if (v != NULL) {
                        if (v->vfs_mountroot != NULL) {
                                error = (v->vfs_mountroot)();
                        }
                        v->vfs_refcount--;
                }
                goto done;
        }

        /*
         * Try each file system currently configured into the kernel.
         */
        mutex_enter(&vfs_list_lock);
        LIST_FOREACH(v, &vfs_list, vfs_list) {
                if (v->vfs_mountroot == NULL)
                        continue;
#ifdef DEBUG
                aprint_normal("mountroot: trying %s...\n", v->vfs_name);
#endif
                v->vfs_refcount++;
                mutex_exit(&vfs_list_lock);
                error = (*v->vfs_mountroot)();
                mutex_enter(&vfs_list_lock);
                v->vfs_refcount--;
                if (!error) {
                        aprint_normal("root file system type: %s\n",
                            v->vfs_name);
                        break;
                }
        }
        mutex_exit(&vfs_list_lock);

        if (v == NULL) {
                vfs_print_fstypes();
                printf("no file system for %s", device_xname(root_device));
                if (device_class(root_device) == DV_DISK)
                        printf(" (dev 0x%llx)", (unsigned long long)rootdev);
                printf("\n");
                error = EFTYPE;
        }

done:
        if (error && device_class(root_device) == DV_DISK) {
                VOP_CLOSE(rootvp, FREAD, FSCRED);
                vrele(rootvp);
        }
        if (error == 0) {
                extern struct cwdinfo cwdi0;

                CIRCLEQ_FIRST(&mountlist)->mnt_flag |= MNT_ROOTFS;
                CIRCLEQ_FIRST(&mountlist)->mnt_op->vfs_refcount++;

                /*
                 * Get the vnode for '/'.  Set cwdi0.cwdi_cdir to
                 * reference it.
                 */
                error = VFS_ROOT(CIRCLEQ_FIRST(&mountlist), &rootvnode);
                if (error)
                        panic("cannot find root vnode, error=%d", error);
                cwdi0.cwdi_cdir = rootvnode;
                vref(cwdi0.cwdi_cdir);
                VOP_UNLOCK(rootvnode, 0);
                cwdi0.cwdi_rdir = NULL;

                /*
                 * Now that root is mounted, we can fixup initproc's CWD
                 * info.  All other processes are kthreads, which merely
                 * share proc0's CWD info.
                 */
                initproc->p_cwdi->cwdi_cdir = rootvnode;
                vref(initproc->p_cwdi->cwdi_cdir);
                initproc->p_cwdi->cwdi_rdir = NULL;
        }
        return (error);
}

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

        mutex_enter(&mntid_lock);
        mtype = makefstype(mp->mnt_op->vfs_name);
        mp->mnt_stat.f_fsidx.__fsid_val[0] = makedev(mtype, 0);
        mp->mnt_stat.f_fsidx.__fsid_val[1] = mtype;
        mp->mnt_stat.f_fsid = mp->mnt_stat.f_fsidx.__fsid_val[0];
        if (xxxfs_mntid == 0)
                ++xxxfs_mntid;
        tfsid.__fsid_val[0] = makedev(mtype & 0xff, xxxfs_mntid);
        tfsid.__fsid_val[1] = mtype;
        if (!CIRCLEQ_EMPTY(&mountlist)) {
                while (vfs_getvfs(&tfsid)) {
                        tfsid.__fsid_val[0]++;
                        xxxfs_mntid++;
                }
        }
        mp->mnt_stat.f_fsidx.__fsid_val[0] = tfsid.__fsid_val[0];
        mp->mnt_stat.f_fsid = mp->mnt_stat.f_fsidx.__fsid_val[0];
        mutex_exit(&mntid_lock);
}

/*
 * Make a 'unique' number from a mount type name.
 */
long
makefstype(const char *type)
{
        long rv;

        for (rv = 0; *type; type++) {
                rv <<= 2;
                rv ^= *type;
        }
        return rv;
}

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

        memset(vap, 0, sizeof(*vap));

        vap->va_type = VNON;

        /*
         * Assign individually so that it is safe even if size and
         * sign of each member are varied.
         */
        vap->va_mode = VNOVAL;
        vap->va_nlink = VNOVAL;
        vap->va_uid = VNOVAL;
        vap->va_gid = VNOVAL;
        vap->va_fsid = VNOVAL;
        vap->va_fileid = VNOVAL;
        vap->va_size = VNOVAL;
        vap->va_blocksize = VNOVAL;
        vap->va_atime.tv_sec =
            vap->va_mtime.tv_sec =
            vap->va_ctime.tv_sec =
            vap->va_birthtime.tv_sec = VNOVAL;
        vap->va_atime.tv_nsec =
            vap->va_mtime.tv_nsec =
            vap->va_ctime.tv_nsec =
            vap->va_birthtime.tv_nsec = VNOVAL;
        vap->va_gen = VNOVAL;
        vap->va_flags = VNOVAL;
        vap->va_rdev = VNOVAL;
        vap->va_bytes = VNOVAL;
}

#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
#define ARRAY_PRINT(idx, arr) \
    ((unsigned int)(idx) < ARRAY_SIZE(arr) ? (arr)[(idx)] : "UNKNOWN")

const char * const vnode_tags[] = { VNODE_TAGS };
const char * const vnode_types[] = { VNODE_TYPES };
const char vnode_flagbits[] = VNODE_FLAGBITS;

/*
 * Print out a description of a vnode.
 */
void
vprint(const char *label, struct vnode *vp)
{
        struct vnlock *vl;
        char bf[96];
        int flag;

        vl = (vp->v_vnlock != NULL ? vp->v_vnlock : &vp->v_lock);
        flag = vp->v_iflag | vp->v_vflag | vp->v_uflag;
        snprintb(bf, sizeof(bf), vnode_flagbits, flag);

        if (label != NULL)
                printf("%s: ", label);
        printf("vnode @ %p, flags (%s)\n\ttag %s(%d), type %s(%d), "
            "usecount %d, writecount %d, holdcount %d\n"
            "\tfreelisthd %p, mount %p, data %p lock %p recursecnt %d\n",
            vp, bf, ARRAY_PRINT(vp->v_tag, vnode_tags), vp->v_tag,
            ARRAY_PRINT(vp->v_type, vnode_types), vp->v_type,
            vp->v_usecount, vp->v_writecount, vp->v_holdcnt,
            vp->v_freelisthd, vp->v_mount, vp->v_data, vl, vl->vl_recursecnt);
        if (vp->v_data != NULL) {
                printf("\t");
                VOP_PRINT(vp);
        }
}

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

        printf("Locked vnodes\n");
        mutex_enter(&mountlist_lock);
        for (mp = CIRCLEQ_FIRST(&mountlist); mp != (void *)&mountlist;
             mp = nmp) {
                if (vfs_busy(mp, &nmp)) {
                        continue;
                }
                TAILQ_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes) {
                        if (VOP_ISLOCKED(vp))
                                vprint(NULL, vp);
                }
                mutex_enter(&mountlist_lock);
                vfs_unbusy(mp, false, &nmp);
        }
        mutex_exit(&mountlist_lock);
}
#endif

/* Deprecated. Kept for KPI compatibility. */
int
vaccess(enum vtype type, mode_t file_mode, uid_t uid, gid_t gid,
    mode_t acc_mode, kauth_cred_t cred)
{

#ifdef DIAGNOSTIC
        printf("vaccess: deprecated interface used.\n");
#endif /* DIAGNOSTIC */

        return genfs_can_access(type, file_mode, uid, gid, acc_mode, cred);
}

/*
 * Given a file system name, look up the vfsops for that
 * file system, or return NULL if file system isn't present
 * in the kernel.
 */
struct vfsops *
vfs_getopsbyname(const char *name)
{
        struct vfsops *v;

        mutex_enter(&vfs_list_lock);
        LIST_FOREACH(v, &vfs_list, vfs_list) {
                if (strcmp(v->vfs_name, name) == 0)
                        break;
        }
        if (v != NULL)
                v->vfs_refcount++;
        mutex_exit(&vfs_list_lock);

        return (v);
}

void
copy_statvfs_info(struct statvfs *sbp, const struct mount *mp)
{
        const struct statvfs *mbp;

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

        (void)memcpy(&sbp->f_fsidx, &mbp->f_fsidx, sizeof(sbp->f_fsidx));
        sbp->f_fsid = mbp->f_fsid;
        sbp->f_owner = mbp->f_owner;
        sbp->f_flag = mbp->f_flag;
        sbp->f_syncwrites = mbp->f_syncwrites;
        sbp->f_asyncwrites = mbp->f_asyncwrites;
        sbp->f_syncreads = mbp->f_syncreads;
        sbp->f_asyncreads = mbp->f_asyncreads;
        (void)memcpy(sbp->f_spare, mbp->f_spare, sizeof(mbp->f_spare));
        (void)memcpy(sbp->f_fstypename, mbp->f_fstypename,
            sizeof(sbp->f_fstypename));
        (void)memcpy(sbp->f_mntonname, mbp->f_mntonname,
            sizeof(sbp->f_mntonname));
        (void)memcpy(sbp->f_mntfromname, mp->mnt_stat.f_mntfromname,
            sizeof(sbp->f_mntfromname));
        sbp->f_namemax = mbp->f_namemax;
}

int
set_statvfs_info(const char *onp, int ukon, const char *fromp, int ukfrom,
    const char *vfsname, struct mount *mp, struct lwp *l)
{
        int error;
        size_t size;
        struct statvfs *sfs = &mp->mnt_stat;
        int (*fun)(const void *, void *, size_t, size_t *);

        (void)strlcpy(mp->mnt_stat.f_fstypename, vfsname,
            sizeof(mp->mnt_stat.f_fstypename));

        if (onp) {
                struct cwdinfo *cwdi = l->l_proc->p_cwdi;
                fun = (ukon == UIO_SYSSPACE) ? copystr : copyinstr;
                if (cwdi->cwdi_rdir != NULL) {
                        size_t len;
                        char *bp;
                        char *path = PNBUF_GET();

                        bp = path + MAXPATHLEN;
                        *--bp = '\0';
                        rw_enter(&cwdi->cwdi_lock, RW_READER);
                        error = getcwd_common(cwdi->cwdi_rdir, rootvnode, &bp,
                            path, MAXPATHLEN / 2, 0, l);
                        rw_exit(&cwdi->cwdi_lock);
                        if (error) {
                                PNBUF_PUT(path);
                                return error;
                        }

                        len = strlen(bp);
                        if (len > sizeof(sfs->f_mntonname) - 1)
                                len = sizeof(sfs->f_mntonname) - 1;
                        (void)strncpy(sfs->f_mntonname, bp, len);
                        PNBUF_PUT(path);

                        if (len < sizeof(sfs->f_mntonname) - 1) {
                                error = (*fun)(onp, &sfs->f_mntonname[len],
                                    sizeof(sfs->f_mntonname) - len - 1, &size);
                                if (error)
                                        return error;
                                size += len;
                        } else {
                                size = len;
                        }
                } else {
                        error = (*fun)(onp, &sfs->f_mntonname,
                            sizeof(sfs->f_mntonname) - 1, &size);
                        if (error)
                                return error;
                }
                (void)memset(sfs->f_mntonname + size, 0,
                    sizeof(sfs->f_mntonname) - size);
        }

        if (fromp) {
                fun = (ukfrom == UIO_SYSSPACE) ? copystr : copyinstr;
                error = (*fun)(fromp, sfs->f_mntfromname,
                    sizeof(sfs->f_mntfromname) - 1, &size);
                if (error)
                        return error;
                (void)memset(sfs->f_mntfromname + size, 0,
                    sizeof(sfs->f_mntfromname) - size);
        }
        return 0;
}

void
vfs_timestamp(struct timespec *ts)
{

        nanotime(ts);
}

time_t  rootfstime;                     /* recorded root fs time, if known */
void
setrootfstime(time_t t)
{
        rootfstime = t;
}

/*
 * Sham lock manager for vnodes.  This is a temporary measure.
 */
int
vlockmgr(struct vnlock *vl, int flags)
{

        KASSERT((flags & ~(LK_CANRECURSE | LK_NOWAIT | LK_TYPE_MASK)) == 0);

        switch (flags & LK_TYPE_MASK) {
        case LK_SHARED:
                if (rw_tryenter(&vl->vl_lock, RW_READER)) {
                        return 0;
                }
                if ((flags & LK_NOWAIT) != 0) {
                        return EBUSY;
                }
                rw_enter(&vl->vl_lock, RW_READER);
                return 0;

        case LK_EXCLUSIVE:
                if (rw_tryenter(&vl->vl_lock, RW_WRITER)) {
                        return 0;
                }
                if ((vl->vl_canrecurse || (flags & LK_CANRECURSE) != 0) &&
                    rw_write_held(&vl->vl_lock)) {
                        vl->vl_recursecnt++;
                        return 0;
                }
                if ((flags & LK_NOWAIT) != 0) {
                        return EBUSY;
                }
                rw_enter(&vl->vl_lock, RW_WRITER);
                return 0;

        case LK_RELEASE:
                if (vl->vl_recursecnt != 0) {
                        KASSERT(rw_write_held(&vl->vl_lock));
                        vl->vl_recursecnt--;
                        return 0;
                }
                rw_exit(&vl->vl_lock);
                return 0;

        default:
                panic("vlockmgr: flags %x", flags);
        }
}

int
vlockstatus(struct vnlock *vl)
{

        if (rw_write_held(&vl->vl_lock)) {
                return LK_EXCLUSIVE;
        }
        if (rw_read_held(&vl->vl_lock)) {
                return LK_SHARED;
        }
        return 0;
}

/*
 * mount_specific_key_create --
 *      Create a key for subsystem mount-specific data.
 */
int
mount_specific_key_create(specificdata_key_t *keyp, specificdata_dtor_t dtor)
{

        return (specificdata_key_create(mount_specificdata_domain, keyp, dtor));
}

/*
 * mount_specific_key_delete --
 *      Delete a key for subsystem mount-specific data.
 */
void
mount_specific_key_delete(specificdata_key_t key)
{

        specificdata_key_delete(mount_specificdata_domain, key);
}

/*
 * mount_initspecific --
 *      Initialize a mount's specificdata container.
 */
void
mount_initspecific(struct mount *mp)
{
        int error;

        error = specificdata_init(mount_specificdata_domain,
                                  &mp->mnt_specdataref);
        KASSERT(error == 0);
}

/*
 * mount_finispecific --
 *      Finalize a mount's specificdata container.
 */
void
mount_finispecific(struct mount *mp)
{

        specificdata_fini(mount_specificdata_domain, &mp->mnt_specdataref);
}

/*
 * mount_getspecific --
 *      Return mount-specific data corresponding to the specified key.
 */
void *
mount_getspecific(struct mount *mp, specificdata_key_t key)
{

        return (specificdata_getspecific(mount_specificdata_domain,
                                         &mp->mnt_specdataref, key));
}

/*
 * mount_setspecific --
 *      Set mount-specific data corresponding to the specified key.
 */
void
mount_setspecific(struct mount *mp, specificdata_key_t key, void *data)
{

        specificdata_setspecific(mount_specificdata_domain,
                                 &mp->mnt_specdataref, key, data);
}

int
VFS_MOUNT(struct mount *mp, const char *a, void *b, size_t *c)
{
        int error;

        KERNEL_LOCK(1, NULL);
        error = (*(mp->mnt_op->vfs_mount))(mp, a, b, c);
        KERNEL_UNLOCK_ONE(NULL);

        return error;
}
        
int
VFS_START(struct mount *mp, int a)
{
        int error;

        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_LOCK(1, NULL);
        }
        error = (*(mp->mnt_op->vfs_start))(mp, a);
        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_UNLOCK_ONE(NULL);
        }

        return error;
}
        
int
VFS_UNMOUNT(struct mount *mp, int a)
{
        int error;

        KERNEL_LOCK(1, NULL);
        error = (*(mp->mnt_op->vfs_unmount))(mp, a);
        KERNEL_UNLOCK_ONE(NULL);

        return error;
}

int
VFS_ROOT(struct mount *mp, struct vnode **a)
{
        int error;

        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_LOCK(1, NULL);
        }
        error = (*(mp->mnt_op->vfs_root))(mp, a);
        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_UNLOCK_ONE(NULL);
        }

        return error;
}

int
VFS_QUOTACTL(struct mount *mp, int a, uid_t b, void *c)
{
        int error;

        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_LOCK(1, NULL);
        }
        error = (*(mp->mnt_op->vfs_quotactl))(mp, a, b, c);
        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_UNLOCK_ONE(NULL);
        }

        return error;
}

int
VFS_STATVFS(struct mount *mp, struct statvfs *a)
{
        int error;

        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_LOCK(1, NULL);
        }
        error = (*(mp->mnt_op->vfs_statvfs))(mp, a);
        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_UNLOCK_ONE(NULL);
        }

        return error;
}

int
VFS_SYNC(struct mount *mp, int a, struct kauth_cred *b)
{
        int error;

        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_LOCK(1, NULL);
        }
        error = (*(mp->mnt_op->vfs_sync))(mp, a, b);
        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_UNLOCK_ONE(NULL);
        }

        return error;
}

int
VFS_FHTOVP(struct mount *mp, struct fid *a, struct vnode **b)
{
        int error;

        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_LOCK(1, NULL);
        }
        error = (*(mp->mnt_op->vfs_fhtovp))(mp, a, b);
        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_UNLOCK_ONE(NULL);
        }

        return error;
}

int
VFS_VPTOFH(struct vnode *vp, struct fid *a, size_t *b)
{
        int error;

        if ((vp->v_vflag & VV_MPSAFE) == 0) {
                KERNEL_LOCK(1, NULL);
        }
        error = (*(vp->v_mount->mnt_op->vfs_vptofh))(vp, a, b);
        if ((vp->v_vflag & VV_MPSAFE) == 0) {
                KERNEL_UNLOCK_ONE(NULL);
        }

        return error;
}

int
VFS_SNAPSHOT(struct mount *mp, struct vnode *a, struct timespec *b)
{
        int error;

        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_LOCK(1, NULL);
        }
        error = (*(mp->mnt_op->vfs_snapshot))(mp, a, b);
        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_UNLOCK_ONE(NULL);
        }

        return error;
}

int
VFS_EXTATTRCTL(struct mount *mp, int a, struct vnode *b, int c, const char *d)
{
        int error;

        KERNEL_LOCK(1, NULL);           /* XXXSMP check ffs */
        error = (*(mp->mnt_op->vfs_extattrctl))(mp, a, b, c, d);
        KERNEL_UNLOCK_ONE(NULL);        /* XXX */

        return error;
}

int
VFS_SUSPENDCTL(struct mount *mp, int a)
{
        int error;

        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_LOCK(1, NULL);
        }
        error = (*(mp->mnt_op->vfs_suspendctl))(mp, a);
        if ((mp->mnt_iflag & IMNT_MPSAFE) == 0) {
                KERNEL_UNLOCK_ONE(NULL);
        }

        return error;
}

#if defined(DDB) || defined(DEBUGPRINT)
static const char buf_flagbits[] = BUF_FLAGBITS;

void
vfs_buf_print(struct buf *bp, int full, void (*pr)(const char *, ...))
{
        char bf[1024];

        (*pr)("  vp %p lblkno 0x%"PRIx64" blkno 0x%"PRIx64" rawblkno 0x%"
            PRIx64 " dev 0x%x\n",
            bp->b_vp, bp->b_lblkno, bp->b_blkno, bp->b_rawblkno, bp->b_dev);

        snprintb(bf, sizeof(bf),
            buf_flagbits, bp->b_flags | bp->b_oflags | bp->b_cflags);
        (*pr)("  error %d flags 0x%s\n", bp->b_error, bf);

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


void
vfs_vnode_print(struct vnode *vp, int full, void (*pr)(const char *, ...))
{
        char bf[256];

        uvm_object_printit(&vp->v_uobj, full, pr);
        snprintb(bf, sizeof(bf),
            vnode_flagbits, vp->v_iflag | vp->v_vflag | vp->v_uflag);
        (*pr)("\nVNODE flags %s\n", bf);
        (*pr)("mp %p numoutput %d size 0x%llx writesize 0x%llx\n",
              vp->v_mount, vp->v_numoutput, vp->v_size, vp->v_writesize);

        (*pr)("data %p writecount %ld holdcnt %ld\n",
              vp->v_data, vp->v_writecount, vp->v_holdcnt);

        (*pr)("tag %s(%d) type %s(%d) mount %p typedata %p\n",
              ARRAY_PRINT(vp->v_tag, vnode_tags), vp->v_tag,
              ARRAY_PRINT(vp->v_type, vnode_types), vp->v_type,
              vp->v_mount, vp->v_mountedhere);

        (*pr)("v_lock %p v_vnlock %p\n", &vp->v_lock, vp->v_vnlock);

        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, void (*pr)(const char *, ...))
{
        char sbuf[256];

        (*pr)("vnodecovered = %p syncer = %p data = %p\n",
                        mp->mnt_vnodecovered,mp->mnt_syncer,mp->mnt_data);

        (*pr)("fs_bshift %d dev_bshift = %d\n",
                        mp->mnt_fs_bshift,mp->mnt_dev_bshift);

        snprintb(sbuf, sizeof(sbuf), __MNT_FLAG_BITS, mp->mnt_flag);
        (*pr)("flag = %s\n", sbuf);

        snprintb(sbuf, sizeof(sbuf), __IMNT_FLAG_BITS, mp->mnt_iflag);
        (*pr)("iflag = %s\n", sbuf);

        (*pr)("refcnt = %d unmounting @ %p updating @ %p\n", mp->mnt_refcnt,
            &mp->mnt_unmounting, &mp->mnt_updating);

        (*pr)("statvfs cache:\n");
        (*pr)("\tbsize = %lu\n",mp->mnt_stat.f_bsize);
        (*pr)("\tfrsize = %lu\n",mp->mnt_stat.f_frsize);
        (*pr)("\tiosize = %lu\n",mp->mnt_stat.f_iosize);

        (*pr)("\tblocks = %"PRIu64"\n",mp->mnt_stat.f_blocks);
        (*pr)("\tbfree = %"PRIu64"\n",mp->mnt_stat.f_bfree);
        (*pr)("\tbavail = %"PRIu64"\n",mp->mnt_stat.f_bavail);
        (*pr)("\tbresvd = %"PRIu64"\n",mp->mnt_stat.f_bresvd);

        (*pr)("\tfiles = %"PRIu64"\n",mp->mnt_stat.f_files);
        (*pr)("\tffree = %"PRIu64"\n",mp->mnt_stat.f_ffree);
        (*pr)("\tfavail = %"PRIu64"\n",mp->mnt_stat.f_favail);
        (*pr)("\tfresvd = %"PRIu64"\n",mp->mnt_stat.f_fresvd);

        (*pr)("\tf_fsidx = { 0x%"PRIx32", 0x%"PRIx32" }\n",
                        mp->mnt_stat.f_fsidx.__fsid_val[0],
                        mp->mnt_stat.f_fsidx.__fsid_val[1]);

        (*pr)("\towner = %"PRIu32"\n",mp->mnt_stat.f_owner);
        (*pr)("\tnamemax = %lu\n",mp->mnt_stat.f_namemax);

        snprintb(sbuf, sizeof(sbuf), __MNT_FLAG_BITS, mp->mnt_stat.f_flag);

        (*pr)("\tflag = %s\n",sbuf);
        (*pr)("\tsyncwrites = %" PRIu64 "\n",mp->mnt_stat.f_syncwrites);
        (*pr)("\tasyncwrites = %" PRIu64 "\n",mp->mnt_stat.f_asyncwrites);
        (*pr)("\tsyncreads = %" PRIu64 "\n",mp->mnt_stat.f_syncreads);
        (*pr)("\tasyncreads = %" PRIu64 "\n",mp->mnt_stat.f_asyncreads);
        (*pr)("\tfstypename = %s\n",mp->mnt_stat.f_fstypename);
        (*pr)("\tmntonname = %s\n",mp->mnt_stat.f_mntonname);
        (*pr)("\tmntfromname = %s\n",mp->mnt_stat.f_mntfromname);

        {
                int cnt = 0;
                struct vnode *vp;
                (*pr)("locked vnodes =");
                TAILQ_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes) {
                        if (VOP_ISLOCKED(vp)) {
                                if ((++cnt % 6) == 0) {
                                        (*pr)(" %p,\n\t", vp);
                                } else {
                                        (*pr)(" %p,", vp);
                                }
                        }
                }
                (*pr)("\n");
        }

        if (full) {
                int cnt = 0;
                struct vnode *vp;
                (*pr)("all vnodes =");
                TAILQ_FOREACH(vp, &mp->mnt_vnodelist, v_mntvnodes) {
                        if (!TAILQ_NEXT(vp, v_mntvnodes)) {
                                (*pr)(" %p", vp);
                        } else if ((++cnt % 6) == 0) {
                                (*pr)(" %p,\n\t", vp);
                        } else {
                                (*pr)(" %p,", vp);
                        }
                }
                (*pr)("\n", vp);
        }
}
#endif /* DDB || DEBUGPRINT */

/*
 * Check if a device pointed to by vp is mounted.
 *
 * Returns:
 *   EINVAL     if it's not a disk
 *   EBUSY      if it's a disk and mounted
 *   0          if it's a disk and not mounted
 */
int
rawdev_mounted(struct vnode *vp, struct vnode **bvpp)
{
        struct vnode *bvp;
        dev_t dev;
        int d_type;

        bvp = NULL;
        dev = vp->v_rdev;
        d_type = D_OTHER;

        if (iskmemvp(vp))
                return EINVAL;

        switch (vp->v_type) {
        case VCHR: {
                const struct cdevsw *cdev;

                cdev = cdevsw_lookup(dev);
                if (cdev != NULL) {
                        dev_t blkdev;

                        blkdev = devsw_chr2blk(dev);
                        if (blkdev != NODEV) {
                                vfinddev(blkdev, VBLK, &bvp);
                                if (bvp != NULL)
                                        d_type = (cdev->d_flag & D_TYPEMASK);
                        }
                }

                break;
                }

        case VBLK: {
                const struct bdevsw *bdev;

                bdev = bdevsw_lookup(dev);
                if (bdev != NULL)
                        d_type = (bdev->d_flag & D_TYPEMASK);

                bvp = vp;

                break;
                }

        default:
                break;
        }

        if (d_type != D_DISK)
                return EINVAL;

        if (bvpp != NULL)
                *bvpp = bvp;

        /*
         * XXX: This is bogus. We should be failing the request
         * XXX: not only if this specific slice is mounted, but
         * XXX: if it's on a disk with any other mounted slice.
         */
        if (vfs_mountedon(bvp))
                return EBUSY;

        return 0;
}