kernel - VM PAGER part 2/2 - Expand vinitvmio() and vnode_pager_alloc()

[dragonfly.git] / sys / vfs / msdosfs / msdosfs_denode.c

/* $FreeBSD: src/sys/msdosfs/msdosfs_denode.c,v 1.47.2.3 2002/08/22 16:20:15 trhodes Exp $ */
/* $DragonFly: src/sys/vfs/msdosfs/msdosfs_denode.c,v 1.35 2008/06/08 07:56:06 nth Exp $ */
/*      $NetBSD: msdosfs_denode.c,v 1.28 1998/02/10 14:10:00 mrg Exp $  */

/*-
 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
 * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
 * All rights reserved.
 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by TooLs GmbH.
 * 4. The name of TooLs GmbH may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``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 TOOLS GMBH 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.
 */
/*
 * Written by Paul Popelka (paulp@uts.amdahl.com)
 *
 * You can do anything you want with this software, just don't say you wrote
 * it, and don't remove this notice.
 *
 * This software is provided "as is".
 *
 * The author supplies this software to be publicly redistributed on the
 * understanding that the author is not responsible for the correct
 * functioning of this software in any circumstances and is not liable for
 * any damages caused by this software.
 *
 * October 1992
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/mount.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/vnode.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>

#include "bpb.h"
#include "msdosfsmount.h"
#include "direntry.h"
#include "denode.h"
#include "fat.h"

static int msdosfs_hashins (struct denode *dep);
static void msdosfs_hashrem (struct denode *dep);

static MALLOC_DEFINE(M_MSDOSFSNODE, "MSDOSFS node", "MSDOSFS vnode private part");

/*
 * Hash table caching denode instances.
 *
 * denodes are keyed by the disk location (cluster num, entry offset) of the
 * directory entry of the file they represent.
 *
 * denodes representing deleted but still opened files are left in this cache
 * until reclaimed.  Deleted directory entries can be reused when files are
 * renamed or new files created.  As a consequence, several denodes associated
 * with the same entry may coexist in this cache as long as a single one of
 * them map to an existing file (de_refcnt > 0).
 *
 * R/w access to this cache is protected by dehash_token.
 */
static struct denode **dehashtbl;
static u_long dehash;                   /* size of hash table - 1 */
#define DEHASH(dev, dcl, doff)  (dehashtbl[(minor(dev) + (dcl) + (doff) /       \
                                sizeof(struct direntry)) & dehash])
static struct lwkt_token dehash_token;

union _qcvt {
        quad_t qcvt;
        long val[2];
};
#define SETHIGH(q, h) { \
        union _qcvt tmp; \
        tmp.qcvt = (q); \
        tmp.val[_QUAD_HIGHWORD] = (h); \
        (q) = tmp.qcvt; \
}
#define SETLOW(q, l) { \
        union _qcvt tmp; \
        tmp.qcvt = (q); \
        tmp.val[_QUAD_LOWWORD] = (l); \
        (q) = tmp.qcvt; \
}

static struct denode *
                msdosfs_hashget (cdev_t dev, u_long dirclust, u_long diroff);

/*ARGSUSED*/
int 
msdosfs_init(struct vfsconf *vfsp)
{
        dehash = 16;
        while (dehash < desiredvnodes)
                dehash <<= 1;
        dehashtbl = kmalloc(sizeof(void *) * dehash, M_MSDOSFSMNT,
                           M_WAITOK|M_ZERO);
        --dehash;
        lwkt_token_init(&dehash_token);
        return (0);
}

int 
msdosfs_uninit(struct vfsconf *vfsp)
{

        if (dehashtbl)
                kfree(dehashtbl, M_MSDOSFSMNT);
        return (0);
}

static struct denode *
msdosfs_hashget(cdev_t dev, u_long dirclust, u_long diroff)
{
        struct denode *dep;
        lwkt_tokref ilock;
        struct vnode *vp;

        lwkt_gettoken(&ilock, &dehash_token);
loop:
        for (dep = DEHASH(dev, dirclust, diroff); dep; dep = dep->de_next) {
                if (dirclust != dep->de_dirclust
                    || diroff != dep->de_diroffset
                    || dev != dep->de_dev
                    || dep->de_refcnt <= 0) {
                        continue;
                }
                vp = DETOV(dep);
                if (vget(vp, LK_EXCLUSIVE))
                        goto loop;

                /*
                 * We must check to see if the inode has been ripped
                 * out from under us after blocking.
                 */
                for (dep = DEHASH(dev, dirclust, diroff); dep; dep = dep->de_next) {
                        if (dirclust == dep->de_dirclust
                            && diroff == dep->de_diroffset
                            && dev == dep->de_dev
                            && dep->de_refcnt > 0) {
                                break;
                        }
                }
                if (dep == NULL || DETOV(dep) != vp) {
                        vput(vp);
                        goto loop;
                }
                lwkt_reltoken(&ilock);
                return (dep);
        }
        lwkt_reltoken(&ilock);
        return (NULL);
}

/*
 * Try to insert specified denode into the hash table.  Return 0 on success
 * and EBUSY if there is already a denode with the same key.
 */
static
int
msdosfs_hashins(struct denode *dep)
{
        struct denode **depp, *deq;
        lwkt_tokref ilock;

        lwkt_gettoken(&ilock, &dehash_token);
        depp = &DEHASH(dep->de_dev, dep->de_dirclust, dep->de_diroffset);
        while ((deq = *depp) != NULL) {
                if (deq->de_dev == dep->de_dev &&
                    deq->de_dirclust == dep->de_dirclust &&
                    deq->de_diroffset == dep->de_diroffset &&
                    deq->de_refcnt > 0) {
                        lwkt_reltoken(&ilock);
                        return(EBUSY);
                }
                depp = &deq->de_next;
        }
        dep->de_next = NULL;
        *depp = dep;
        lwkt_reltoken(&ilock);
        return(0);
}

static
void
msdosfs_hashrem(struct denode *dep)
{
        struct denode **depp, *deq;
        lwkt_tokref ilock;

        lwkt_gettoken(&ilock, &dehash_token);
        depp = &DEHASH(dep->de_dev, dep->de_dirclust, dep->de_diroffset);
        while ((deq = *depp) != NULL) {
                if (dep == deq)
                        break;
                depp = &deq->de_next;
        }
        KKASSERT(dep == deq);
        *depp = dep->de_next;
        dep->de_next = NULL;
        lwkt_reltoken(&ilock);
}

void
msdosfs_reinsert(struct denode *ip, u_long new_dirclust, u_long new_diroffset)
{
        lwkt_tokref ilock;
        int error;

        lwkt_gettoken(&ilock, &dehash_token);
        msdosfs_hashrem(ip);
        ip->de_dirclust = new_dirclust;
        ip->de_diroffset = new_diroffset;
        error = msdosfs_hashins(ip);
        KASSERT(!error, ("msdosfs_reinsert: insertion failed %d", error));
        lwkt_reltoken(&ilock);
}

/*
 * If deget() succeeds it returns with the gotten denode locked().
 *
 * pmp       - address of msdosfsmount structure of the filesystem containing
 *             the denode of interest.  The pm_dev field and the address of
 *             the msdosfsmount structure are used.
 * dirclust  - which cluster bp contains, if dirclust is 0 (root directory)
 *             diroffset is relative to the beginning of the root directory,
 *             otherwise it is cluster relative.
 * diroffset - offset past begin of cluster of denode we want
 * depp      - returns the address of the gotten denode.
 */
int
deget(struct msdosfsmount *pmp, /* so we know the maj/min number */
      u_long dirclust,          /* cluster this dir entry came from */
      u_long diroffset,         /* index of entry within the cluster */
      struct denode **depp)     /* returns the addr of the gotten denode */
{
        int error;
        cdev_t dev = pmp->pm_dev;
        struct mount *mntp = pmp->pm_mountp;
        struct direntry *direntptr;
        struct denode *ldep;
        struct vnode *nvp;
        struct buf *bp;
        struct timeval tv;

#ifdef MSDOSFS_DEBUG
        kprintf("deget(pmp %p, dirclust %lu, diroffset %lx, depp %p)\n",
            pmp, dirclust, diroffset, depp);
#endif

        /*
         * On FAT32 filesystems, root is a (more or less) normal
         * directory
         */
        if (FAT32(pmp) && dirclust == MSDOSFSROOT)
                dirclust = pmp->pm_rootdirblk;

again:
        /*
         * See if the denode is in the denode cache. Use the location of
         * the directory entry to compute the hash value. For subdir use
         * address of "." entry. For root dir (if not FAT32) use cluster
         * MSDOSFSROOT, offset MSDOSFSROOT_OFS
         *
         * NOTE: The check for de_refcnt > 0 below insures the denode being
         * examined does not represent an unlinked but still open file.
         * These files are not to be accessible even when the directory
         * entry that represented the file happens to be reused while the
         * deleted file is still open.
         */
        ldep = msdosfs_hashget(dev, dirclust, diroffset);
        if (ldep) {
                *depp = ldep;
                return (0);
        }

        /*
         * Do the MALLOC before the getnewvnode since doing so afterward
         * might cause a bogus v_data pointer to get dereferenced
         * elsewhere if MALLOC should block.
         */
        MALLOC(ldep, struct denode *, sizeof(struct denode), M_MSDOSFSNODE,
            M_WAITOK | M_ZERO);

        /*
         * Directory entry was not in cache, have to create a vnode and
         * copy it from the passed disk buffer.
         */

        /* getnewvnode() does a vref() on the vnode */
        error = getnewvnode(VT_MSDOSFS, mntp, &nvp, VLKTIMEOUT, 0);
        if (error) {
                *depp = NULL;
                FREE(ldep, M_MSDOSFSNODE);
                return error;
        }

        ldep->de_vnode = nvp;
        ldep->de_flag = 0;
        ldep->de_devvp = 0;
        ldep->de_dev = dev;
        ldep->de_dirclust = dirclust;
        ldep->de_diroffset = diroffset;
        fc_purge(ldep, 0);      /* init the fat cache for this denode */

        /*
         * Insert the denode into the hash queue.  If a collision occurs
         * throw away the vnode and try again.
         */
        error = msdosfs_hashins(ldep);
        if (error == EBUSY) {
                nvp->v_type = VBAD;
                vx_put(nvp);
                kfree(ldep, M_MSDOSFSNODE);
                goto again;
        } else if (error) {
                nvp->v_type = VBAD;
                vx_put(nvp);
                kfree(ldep, M_MSDOSFSNODE);
                *depp = NULL;
                return (EINVAL);
        }
        nvp->v_data = ldep;
        ldep->de_pmp = pmp;
        ldep->de_refcnt = 1;
        /*
         * Copy the directory entry into the denode area of the vnode.
         */
        if ((dirclust == MSDOSFSROOT
             || (FAT32(pmp) && dirclust == pmp->pm_rootdirblk))
            && diroffset == MSDOSFSROOT_OFS) {
                /*
                 * Directory entry for the root directory. There isn't one,
                 * so we manufacture one. We should probably rummage
                 * through the root directory and find a label entry (if it
                 * exists), and then use the time and date from that entry
                 * as the time and date for the root denode.
                 */
                vsetflags(nvp, VROOT); /* should be further down XXX */

                ldep->de_Attributes = ATTR_DIRECTORY;
                ldep->de_LowerCase = 0;
                if (FAT32(pmp))
                        ldep->de_StartCluster = pmp->pm_rootdirblk;
                        /* de_FileSize will be filled in further down */
                else {
                        ldep->de_StartCluster = MSDOSFSROOT;
                        ldep->de_FileSize = pmp->pm_rootdirsize * DEV_BSIZE;
                }
                /*
                 * fill in time and date so that dos2unixtime() doesn't
                 * spit up when called from msdosfs_getattr() with root
                 * denode
                 */
                ldep->de_CHun = 0;
                ldep->de_CTime = 0x0000;        /* 00:00:00      */
                ldep->de_CDate = (0 << DD_YEAR_SHIFT) | (1 << DD_MONTH_SHIFT)
                    | (1 << DD_DAY_SHIFT);
                /* Jan 1, 1980   */
                ldep->de_ADate = ldep->de_CDate;
                ldep->de_MTime = ldep->de_CTime;
                ldep->de_MDate = ldep->de_CDate;
                /* leave the other fields as garbage */
        } else {
                error = readep(pmp, dirclust, diroffset, &bp, &direntptr);
                if (error) {
                        /*
                         * The denode does not contain anything useful, so
                         * it would be wrong to leave it on its hash chain.
                         * Arrange for vput() to just forget about it.
                         */
                        ldep->de_Name[0] = SLOT_DELETED;
                        nvp->v_type = VBAD;

                        vx_put(nvp);
                        *depp = NULL;
                        return (error);
                }
                DE_INTERNALIZE(ldep, direntptr);
                brelse(bp);
        }

        /*
         * Fill in a few fields of the vnode and finish filling in the
         * denode.  Then return the address of the found denode.
         */
        if (ldep->de_Attributes & ATTR_DIRECTORY) {
                /*
                 * Since DOS directory entries that describe directories
                 * have 0 in the filesize field, we take this opportunity
                 * to find out the length of the directory and plug it into
                 * the denode structure.
                 */
                u_long size;

                /*
                 * XXX Sometimes, these arrives that . entry have cluster
                 * number 0, when it shouldn't.  Use real cluster number
                 * instead of what is written in directory entry.
                 */
                if ((diroffset == 0) && (ldep->de_StartCluster != dirclust)) {
                        kprintf("deget(): . entry at clust %ld != %ld\n",
                                        dirclust, ldep->de_StartCluster);
                        ldep->de_StartCluster = dirclust;
                }

                nvp->v_type = VDIR;
                if (ldep->de_StartCluster != MSDOSFSROOT) {
                        error = pcbmap(ldep, 0xffff, NULL, &size, NULL);
                        if (error == E2BIG) {
                                ldep->de_FileSize = de_cn2off(pmp, size);
                                error = 0;
                        } else
                                kprintf("deget(): pcbmap returned %d\n", error);
                }
        } else {
                nvp->v_type = VREG;
        }
        getmicrouptime(&tv);
        SETHIGH(ldep->de_modrev, tv.tv_sec);
        SETLOW(ldep->de_modrev, tv.tv_usec * 4294);
        ldep->de_devvp = pmp->pm_devvp;
        vref(ldep->de_devvp);
        vinitvmio(nvp, ldep->de_FileSize, PAGE_SIZE, -1);
        /*
         * Leave nvp locked and refd so the returned inode is effectively
         * locked and refd.
         */
        *depp = ldep;
        return (0);
}

int
deupdat(struct denode *dep, int waitfor)
{
        int error;
        struct buf *bp;
        struct direntry *dirp;
        struct timespec ts;

        if (DETOV(dep)->v_mount->mnt_flag & MNT_RDONLY)
                return (0);
        getnanotime(&ts);
        DETIMES(dep, &ts, &ts, &ts);
        if ((dep->de_flag & DE_MODIFIED) == 0)
                return (0);
        dep->de_flag &= ~DE_MODIFIED;
        if (dep->de_Attributes & ATTR_DIRECTORY)
                return (0);
        if (dep->de_refcnt <= 0)
                return (0);
        error = readde(dep, &bp, &dirp);
        if (error)
                return (error);
        DE_EXTERNALIZE(dirp, dep);
        if (waitfor)
                return (bwrite(bp));
        else {
                bdwrite(bp);
                return (0);
        }
}

/*
 * Truncate the file described by dep to the length specified by length.
 */
int
detrunc(struct denode *dep, u_long length, int flags)
{
        int error;
        int allerror;
        u_long eofentry;
        u_long chaintofree;
        daddr_t bn, cn;
        int boff;
        int isadir = dep->de_Attributes & ATTR_DIRECTORY;
        struct buf *bp;
        struct msdosfsmount *pmp = dep->de_pmp;

#ifdef MSDOSFS_DEBUG
        kprintf("detrunc(): file %s, length %lu, flags %x\n", dep->de_Name, length, flags);
#endif

        /*
         * Disallow attempts to truncate the root directory since it is of
         * fixed size.  That's just the way dos filesystems are.  We use
         * the VROOT bit in the vnode because checking for the directory
         * bit and a startcluster of 0 in the denode is not adequate to
         * recognize the root directory at this point in a file or
         * directory's life.
         */
        if ((DETOV(dep)->v_flag & VROOT) && !FAT32(pmp)) {
                kprintf("detrunc(): can't truncate root directory, clust %ld, offset %ld\n",
                    dep->de_dirclust, dep->de_diroffset);
                return (EINVAL);
        }


        if (dep->de_FileSize < length) {
                vnode_pager_setsize(DETOV(dep), length);
                return deextend(dep, length);
        }

        /*
         * If the desired length is 0 then remember the starting cluster of
         * the file and set the StartCluster field in the directory entry
         * to 0.  If the desired length is not zero, then get the number of
         * the last cluster in the shortened file.  Then get the number of
         * the first cluster in the part of the file that is to be freed.
         * Then set the next cluster pointer in the last cluster of the
         * file to CLUST_EOFE.
         */
        if (length == 0) {
                chaintofree = dep->de_StartCluster;
                dep->de_StartCluster = 0;
                eofentry = ~0;
        } else {
                error = pcbmap(dep, de_clcount(pmp, length) - 1,
                               NULL, &eofentry, NULL);
                if (error) {
#ifdef MSDOSFS_DEBUG
                        kprintf("detrunc(): pcbmap fails %d\n", error);
#endif
                        return (error);
                }
        }

        fc_purge(dep, de_clcount(pmp, length));

        /*
         * If the new length is not a multiple of the cluster size then we
         * must zero the tail end of the new last cluster in case it
         * becomes part of the file again because of a seek.
         */
        if ((boff = length & pmp->pm_crbomask) != 0) {
                if (isadir) {
                        bn = xcntobn(pmp, eofentry);
                        error = bread(pmp->pm_devvp, de_bntodoff(pmp, bn), pmp->pm_bpcluster, &bp);
                } else {
                        cn = de_cluster(pmp, length);
                        error = bread(DETOV(dep), de_cn2doff(pmp, cn), pmp->pm_bpcluster, &bp);
                }
                if (error) {
                        brelse(bp);
#ifdef MSDOSFS_DEBUG
                        kprintf("detrunc(): bread fails %d\n", error);
#endif
                        return (error);
                }
                /*
                 * is this the right place for it?
                 */
                bzero(bp->b_data + boff, pmp->pm_bpcluster - boff);
                if (flags & IO_SYNC)
                        bwrite(bp);
                else
                        bdwrite(bp);
        }

        /*
         * Write out the updated directory entry.  Even if the update fails
         * we free the trailing clusters.
         */
        dep->de_FileSize = length;
        if (!isadir)
                dep->de_flag |= DE_UPDATE|DE_MODIFIED;
        allerror = vtruncbuf(DETOV(dep), length, pmp->pm_bpcluster);
#ifdef MSDOSFS_DEBUG
        if (allerror)
                kprintf("detrunc(): vtruncbuf error %d\n", allerror);
#endif
        error = deupdat(dep, 1);
        if (error && (allerror == 0))
                allerror = error;
#ifdef MSDOSFS_DEBUG
        kprintf("detrunc(): allerror %d, eofentry %lu\n",
               allerror, eofentry);
#endif

        /*
         * If we need to break the cluster chain for the file then do it
         * now.
         */
        if (eofentry != ~0) {
                error = fatentry(FAT_GET_AND_SET, pmp, eofentry,
                                 &chaintofree, CLUST_EOFE);
                if (error) {
#ifdef MSDOSFS_DEBUG
                        kprintf("detrunc(): fatentry errors %d\n", error);
#endif
                        return (error);
                }
                fc_setcache(dep, FC_LASTFC, de_cluster(pmp, length - 1),
                            eofentry);
        }

        /*
         * Now free the clusters removed from the file because of the
         * truncation.
         */
        if (chaintofree != 0 && !MSDOSFSEOF(pmp, chaintofree))
                freeclusterchain(pmp, chaintofree);

        return (allerror);
}

/*
 * Extend the file described by dep to length specified by length.
 */
int
deextend(struct denode *dep, u_long length)
{
        struct msdosfsmount *pmp = dep->de_pmp;
        u_long count;
        int error;

        /*
         * The root of a DOS filesystem cannot be extended.
         */
        if ((DETOV(dep)->v_flag & VROOT) && !FAT32(pmp))
                return (EINVAL);

        /*
         * Directories cannot be extended.
         */
        if (dep->de_Attributes & ATTR_DIRECTORY)
                return (EISDIR);

        if (length <= dep->de_FileSize)
                panic("deextend: file too large");

        /*
         * Compute the number of clusters to allocate.
         */
        count = de_clcount(pmp, length) - de_clcount(pmp, dep->de_FileSize);
        if (count > 0) {
                if (count > pmp->pm_freeclustercount)
                        return (ENOSPC);
                error = extendfile(dep, count, NULL, NULL, DE_CLEAR);
                if (error) {
                        /* truncate the added clusters away again */
                        detrunc(dep, dep->de_FileSize, 0);
                        return (error);
                }
        }
        dep->de_FileSize = length;
        dep->de_flag |= DE_UPDATE|DE_MODIFIED;
        return (deupdat(dep, 1));
}

/*
 * msdosfs_reclaim(struct vnode *a_vp)
 */
int
msdosfs_reclaim(struct vop_reclaim_args *ap)
{
        struct vnode *vp = ap->a_vp;
        struct denode *dep = VTODE(vp);

#ifdef MSDOSFS_DEBUG
        kprintf("msdosfs_reclaim(): dep %p, file %s, refcnt %ld\n",
            dep, dep ? (char *)dep->de_Name : "?", dep ? dep->de_refcnt : -1);
#endif

        if (prtactive && vp->v_sysref.refcnt > 1)
                vprint("msdosfs_reclaim(): pushing active", vp);
        /*
         * Remove the denode from its hash chain.
         */
        vp->v_data = NULL;
        if (dep) {
                msdosfs_hashrem(dep);
                if (dep->de_devvp) {
                        vrele(dep->de_devvp);
                        dep->de_devvp = 0;
                }
                kfree(dep, M_MSDOSFSNODE);
        }
        return (0);
}

/*
 * msdosfs_inactive(struct vnode *a_vp)
 */
int
msdosfs_inactive(struct vop_inactive_args *ap)
{
        struct vnode *vp = ap->a_vp;
        struct denode *dep = VTODE(vp);
        int error = 0;

#ifdef MSDOSFS_DEBUG
        kprintf("msdosfs_inactive(): dep %p, de_Name[0] %x\n",
                dep, (dep ? dep->de_Name[0] : 0));
#endif

        if (prtactive && vp->v_sysref.refcnt > 1)
                vprint("msdosfs_inactive(): pushing active", vp);

        /*
         * Ignore denodes related to stale file handles.
         */
        if (dep == NULL || dep->de_Name[0] == SLOT_DELETED)
                goto out;

        /*
         * If the file has been deleted and it is on a read/write
         * filesystem, then truncate the file, and mark the directory slot
         * as empty.  (This may not be necessary for the dos filesystem.)
         */
#ifdef MSDOSFS_DEBUG
        kprintf("msdosfs_inactive(): dep %p, refcnt %ld, mntflag %x, MNT_RDONLY %x\n",
               dep, dep->de_refcnt, vp->v_mount->mnt_flag, MNT_RDONLY);
#endif
        if (dep->de_refcnt <= 0 && (vp->v_mount->mnt_flag & MNT_RDONLY) == 0) {
                error = detrunc(dep, (u_long) 0, 0);
                dep->de_flag |= DE_UPDATE;
                dep->de_Name[0] = SLOT_DELETED;
        }
        deupdat(dep, 0);

out:
        /*
         * If we are done with the denode, reclaim it
         * so that it can be reused immediately.
         */
#ifdef MSDOSFS_DEBUG
        kprintf("msdosfs_inactive(): v_sysrefs %d, de_Name[0] %x\n",
                vp->v_sysref.refcnt, (dep ? dep->de_Name[0] : 0));
#endif
        if (dep == NULL || dep->de_Name[0] == SLOT_DELETED)
                vrecycle(vp);
        return (error);
}