Remove checks for BOOTSIG[23] from FAT32 bootblocks.

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

/* $FreeBSD: /usr/local/www/cvsroot/FreeBSD/src/sys/msdosfs/Attic/msdosfs_vfsops.c,v 1.60.2.8 2004/03/02 09:43:04 tjr Exp $ */
/* $DragonFly: src/sys/vfs/msdosfs/msdosfs_vfsops.c,v 1.52 2008/09/17 21:44:24 dillon Exp $ */
/*      $NetBSD: msdosfs_vfsops.c,v 1.51 1997/11/17 15:36:58 ws 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/conf.h>
#include <sys/proc.h>
#include <sys/nlookup.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/buf.h>
#include <sys/fcntl.h>
#include <sys/malloc.h>
#include <sys/stat.h>                           /* defines ALLPERMS */
#include <vm/vm_zone.h>

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

extern struct vop_ops msdosfs_vnode_vops;

#define MSDOSFS_DFLTBSIZE       4096

#if 1 /*def PC98*/
/*
 * XXX - The boot signature formatted by NEC PC-98 DOS looks like a
 *       garbage or a random value :-{
 *       If you want to use that broken-signatured media, define the
 *       following symbol even though PC/AT.
 *       (ex. mount PC-98 DOS formatted FD on PC/AT)
 */
#define MSDOSFS_NOCHECKSIG
#endif

MALLOC_DEFINE(M_MSDOSFSMNT, "MSDOSFS mount", "MSDOSFS mount structure");
static MALLOC_DEFINE(M_MSDOSFSFAT, "MSDOSFS FAT", "MSDOSFS file allocation table");

static int      update_mp (struct mount *mp, struct msdosfs_args *argp);
static int      mountmsdosfs (struct vnode *devvp, struct mount *mp,
                                  struct msdosfs_args *argp);
static int      msdosfs_fhtovp (struct mount *, struct vnode *,
                                struct fid *, struct vnode **);
static int      msdosfs_checkexp (struct mount *, struct sockaddr *, 
                                    int *, struct ucred **);
static int      msdosfs_mount (struct mount *, char *, caddr_t,
                                   struct ucred *);
static int      msdosfs_root (struct mount *, struct vnode **);
static int      msdosfs_statfs (struct mount *, struct statfs *,
                                struct ucred *);
static int      msdosfs_sync (struct mount *, int);
static int      msdosfs_unmount (struct mount *, int);
static int      msdosfs_vptofh (struct vnode *, struct fid *);

static int
update_mp(struct mount *mp, struct msdosfs_args *argp)
{
        struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
        int error;

        pmp->pm_gid = argp->gid;
        pmp->pm_uid = argp->uid;
        pmp->pm_mask = argp->mask & ALLPERMS;
        pmp->pm_flags |= argp->flags & MSDOSFSMNT_MNTOPT;
        if (pmp->pm_flags & MSDOSFSMNT_U2WTABLE) {
                bcopy(argp->u2w, pmp->pm_u2w, sizeof(pmp->pm_u2w));
                bcopy(argp->d2u, pmp->pm_d2u, sizeof(pmp->pm_d2u));
                bcopy(argp->u2d, pmp->pm_u2d, sizeof(pmp->pm_u2d));
        }
        if (pmp->pm_flags & MSDOSFSMNT_ULTABLE) {
                bcopy(argp->ul, pmp->pm_ul, sizeof(pmp->pm_ul));
                bcopy(argp->lu, pmp->pm_lu, sizeof(pmp->pm_lu));
        }

#ifndef __DragonFly__
        /*
         * GEMDOS knows nothing (yet) about win95
         */
        if (pmp->pm_flags & MSDOSFSMNT_GEMDOSFS)
                pmp->pm_flags |= MSDOSFSMNT_NOWIN95;
#endif

        if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
                pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
        else if (!(pmp->pm_flags &
            (MSDOSFSMNT_SHORTNAME | MSDOSFSMNT_LONGNAME))) {
                struct vnode *rootvp;

                /*
                 * Try to divine whether to support Win'95 long filenames
                 */
                if (FAT32(pmp))
                        pmp->pm_flags |= MSDOSFSMNT_LONGNAME;
                else {
                        if ((error = msdosfs_root(mp, &rootvp)) != 0)
                                return error;
                        pmp->pm_flags |= findwin95(VTODE(rootvp))
                                ? MSDOSFSMNT_LONGNAME
                                        : MSDOSFSMNT_SHORTNAME;
                        vput(rootvp);
                }
        }
        return 0;
}

/*
 * mp - path - addr in user space of mount point (ie /usr or whatever)
 * data - addr in user space of mount params including the name of the block
 * special file to treat as a filesystem.
 */
static int
msdosfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred)
{
        struct vnode *devvp;      /* vnode for blk device to mount */
        struct msdosfs_args args; /* will hold data from mount request */
        /* msdosfs specific mount control block */
        struct msdosfsmount *pmp = NULL;
        size_t size;
        int error, flags;
        mode_t accessmode;
        struct nlookupdata nd;

        error = copyin(data, (caddr_t)&args, sizeof(struct msdosfs_args));
        if (error)
                return (error);
        if (args.magic != MSDOSFS_ARGSMAGIC)
                args.flags = 0;
        /*
         * If updating, check whether changing from read-only to
         * read/write; if there is no device name, that's all we do.
         */
        if (mp->mnt_flag & MNT_UPDATE) {
                pmp = VFSTOMSDOSFS(mp);
                error = 0;
                if (!(pmp->pm_flags & MSDOSFSMNT_RONLY) && (mp->mnt_flag & MNT_RDONLY)) {
                        flags = WRITECLOSE;
                        if (mp->mnt_flag & MNT_FORCE)
                                flags |= FORCECLOSE;
                        error = vflush(mp, 0, flags);
                        if (error == 0) {
                                devvp = pmp->pm_devvp;
                                VOP_OPEN(devvp, FREAD, FSCRED, NULL);
                                VOP_CLOSE(devvp, FREAD|FWRITE);
                                pmp->pm_flags |= MSDOSFSMNT_RONLY;
                        }
                }
                if (!error && (mp->mnt_flag & MNT_RELOAD))
                        /* not yet implemented */
                        error = EOPNOTSUPP;
                if (error)
                        return (error);
                if ((pmp->pm_flags & MSDOSFSMNT_RONLY) && (mp->mnt_kern_flag & MNTK_WANTRDWR)) {
                        /*
                         * If upgrade to read-write by non-root, then verify
                         * that user has necessary permissions on the device.
                         */
                        devvp = pmp->pm_devvp;
                        vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
                        if (cred->cr_uid != 0) {
                                error = VOP_ACCESS(devvp, VREAD | VWRITE, cred);
                                if (error) {
                                        vn_unlock(devvp);
                                        return (error);
                                }
                        }
                        VOP_OPEN(devvp, FREAD|FWRITE, FSCRED, NULL);
                        VOP_CLOSE(devvp, FREAD);
                        vn_unlock(devvp);
                        pmp->pm_flags &= ~MSDOSFSMNT_RONLY;
                }
                if (args.fspec == 0) {
#ifdef  __notyet__              /* doesn't work correctly with current mountd   XXX */
                        if (args.flags & MSDOSFSMNT_MNTOPT) {
                                pmp->pm_flags &= ~MSDOSFSMNT_MNTOPT;
                                pmp->pm_flags |= args.flags & MSDOSFSMNT_MNTOPT;
                                if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
                                        pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
                        }
#endif
                        /*
                         * Process export requests.
                         */
                        return (vfs_export(mp, &pmp->pm_export, &args.export));
                }
        }
        /*
         * Not an update, or updating the name: look up the name
         * and verify that it refers to a sensible block device.
         */
        devvp = NULL;
        error = nlookup_init(&nd, args.fspec, UIO_USERSPACE, NLC_FOLLOW);
        if (error == 0)
                error = nlookup(&nd);
        if (error == 0)
                error = cache_vref(&nd.nl_nch, nd.nl_cred, &devvp);
        nlookup_done(&nd);
        if (error)
                return (error);

        if (!vn_isdisk(devvp, &error)) {
                vrele(devvp);
                return (error);
        }
        /*
         * If mount by non-root, then verify that user has necessary
         * permissions on the device.
         */
        if (cred->cr_uid != 0) {
                accessmode = VREAD;
                if ((mp->mnt_flag & MNT_RDONLY) == 0)
                        accessmode |= VWRITE;
                vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
                error = VOP_ACCESS(devvp, accessmode, cred);
                if (error) {
                        vput(devvp);
                        return (error);
                }
                vn_unlock(devvp);
        }
        if ((mp->mnt_flag & MNT_UPDATE) == 0) {
                error = mountmsdosfs(devvp, mp, &args);
#ifdef MSDOSFS_DEBUG            /* only needed for the kprintf below */
                pmp = VFSTOMSDOSFS(mp);
#endif
        } else {
                if (devvp != pmp->pm_devvp)
                        error = EINVAL; /* XXX needs translation */
                else
                        vrele(devvp);
        }
        if (error) {
                vrele(devvp);
                return (error);
        }

        error = update_mp(mp, &args);
        if (error) {
                msdosfs_unmount(mp, MNT_FORCE);
                return error;
        }

        copyinstr(args.fspec, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, &size);
        bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
        msdosfs_statfs(mp, &mp->mnt_stat, cred);
#ifdef MSDOSFS_DEBUG
        kprintf("msdosfs_mount(): mp %p, pmp %p, inusemap %p\n", mp, pmp, pmp->pm_inusemap);
#endif
        return (0);
}

static int
mountmsdosfs(struct vnode *devvp, struct mount *mp, struct msdosfs_args *argp)
{
        struct msdosfsmount *pmp;
        struct buf *bp;
        cdev_t dev;
        union bootsector *bsp;
        struct byte_bpb33 *b33;
        struct byte_bpb50 *b50;
        struct byte_bpb710 *b710;
        u_int8_t SecPerClust;
        u_long clusters;
        int     ronly, error;

        /*
         * Disallow multiple mounts of the same device.
         * Disallow mounting of a device that is currently in use
         * Flush out any old buffers remaining from a previous use.
         */
        error = vfs_mountedon(devvp);
        if (error)
                return (error);
        if (count_udev(devvp->v_umajor, devvp->v_uminor) > 0)
                return (EBUSY);
        vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
        error = vinvalbuf(devvp, V_SAVE, 0, 0);
        vn_unlock(devvp);
        if (error)
                return (error);

        ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
        vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
        error = VOP_OPEN(devvp, ronly ? FREAD : FREAD|FWRITE, FSCRED, NULL);
        vn_unlock(devvp);
        if (error)
                return (error);
        dev = devvp->v_rdev;
        bp  = NULL; /* both used in error_exit */
        pmp = NULL;

        /*
         * Read the boot sector of the filesystem, and then check the
         * boot signature.  If not a dos boot sector then error out.
         *
         * NOTE: 2048 is a maximum sector size in current...
         */
        error = bread(devvp, 0, 2048, &bp);
        if (error)
                goto error_exit;
        bp->b_flags |= B_AGE;
        bsp = (union bootsector *)bp->b_data;
        b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
        b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
        b710 = (struct byte_bpb710 *)bsp->bs710.bsPBP;

#ifndef __DragonFly__
        if (!(argp->flags & MSDOSFSMNT_GEMDOSFS)) {
#endif
#ifndef MSDOSFS_NOCHECKSIG
                if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
                    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
                        error = EINVAL;
                        goto error_exit;
                }
#endif
#ifndef __DragonFly__
        }
#endif

        pmp = kmalloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK | M_ZERO);
        pmp->pm_mountp = mp;

        /*
         * Compute several useful quantities from the bpb in the
         * bootsector.  Copy in the dos 5 variant of the bpb then fix up
         * the fields that are different between dos 5 and dos 3.3.
         */
        SecPerClust = b50->bpbSecPerClust;
        pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
        pmp->pm_ResSectors = getushort(b50->bpbResSectors);
        pmp->pm_FATs = b50->bpbFATs;
        pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
        pmp->pm_Sectors = getushort(b50->bpbSectors);
        pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
        pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
        pmp->pm_Heads = getushort(b50->bpbHeads);
        pmp->pm_Media = b50->bpbMedia;

        /* calculate the ratio of sector size to DEV_BSIZE */
        pmp->pm_BlkPerSec = pmp->pm_BytesPerSec / DEV_BSIZE;

#ifndef __DragonFly__
        if (!(argp->flags & MSDOSFSMNT_GEMDOSFS)) {
#endif
                /*
                 * We don't check pm_Heads nor pm_SecPerTrack, because
                 * these may not be set for EFI file systems. We don't
                 * use these anyway, so we're unaffected if they are
                 * invalid.
                 */
                if (!pmp->pm_BytesPerSec || !SecPerClust) {
                        error = EINVAL;
                        goto error_exit;
                }
#ifndef __DragonFly__
        }
#endif

        if (pmp->pm_Sectors == 0) {
                pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
                pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
        } else {
                pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
                pmp->pm_HugeSectors = pmp->pm_Sectors;
        }

        if (pmp->pm_RootDirEnts == 0) {
                if (pmp->pm_Sectors
                    || pmp->pm_FATsecs
                    || getushort(b710->bpbFSVers)) {
                        error = EINVAL;
                        kprintf("mountmsdosfs(): bad FAT32 filesystem\n");
                        goto error_exit;
                }
                pmp->pm_fatmask = FAT32_MASK;
                pmp->pm_fatmult = 4;
                pmp->pm_fatdiv = 1;
                pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);
                if (getushort(b710->bpbExtFlags) & FATMIRROR)
                        pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
                else
                        pmp->pm_flags |= MSDOSFS_FATMIRROR;
        } else
                pmp->pm_flags |= MSDOSFS_FATMIRROR;

        /*
         * Check a few values (could do some more):
         * - logical sector size: power of 2, >= block size
         * - sectors per cluster: power of 2, >= 1
         * - number of sectors:   >= 1, <= size of partition
         */
        if ( (SecPerClust == 0)
          || (SecPerClust & (SecPerClust - 1))
          || (pmp->pm_BytesPerSec < DEV_BSIZE)
          || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
          || (pmp->pm_HugeSectors == 0)
        ) {
                error = EINVAL;
                goto error_exit;
        }

        pmp->pm_HugeSectors *= pmp->pm_BlkPerSec;
        pmp->pm_HiddenSects *= pmp->pm_BlkPerSec; /* XXX not used? */
        pmp->pm_FATsecs     *= pmp->pm_BlkPerSec;
        SecPerClust         *= pmp->pm_BlkPerSec;

        pmp->pm_fatblk = pmp->pm_ResSectors * pmp->pm_BlkPerSec;

        if (FAT32(pmp)) {
                pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
                pmp->pm_firstcluster = pmp->pm_fatblk
                        + (pmp->pm_FATs * pmp->pm_FATsecs);
                pmp->pm_fsinfo = getushort(b710->bpbFSInfo) * pmp->pm_BlkPerSec;
        } else {
                pmp->pm_rootdirblk = pmp->pm_fatblk +
                        (pmp->pm_FATs * pmp->pm_FATsecs);
                pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
                                       + DEV_BSIZE - 1)
                        / DEV_BSIZE; /* in blocks */
                pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
        }

        pmp->pm_maxcluster = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
            SecPerClust + 1;
        pmp->pm_fatsize = pmp->pm_FATsecs * DEV_BSIZE; /* XXX not used? */

#ifndef __DragonFly__
        if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
                if ((pmp->pm_maxcluster <= (0xff0 - 2))
                      && ((dtype == DTYPE_FLOPPY) || ((dtype == DTYPE_VNODE)
                      && ((pmp->pm_Heads == 1) || (pmp->pm_Heads == 2))))
                    ) {
                        pmp->pm_fatmask = FAT12_MASK;
                        pmp->pm_fatmult = 3;
                        pmp->pm_fatdiv = 2;
                } else {
                        pmp->pm_fatmask = FAT16_MASK;
                        pmp->pm_fatmult = 2;
                        pmp->pm_fatdiv = 1;
                }
        } else 
#endif
        if (pmp->pm_fatmask == 0) {
                if (pmp->pm_maxcluster
                    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
                        /*
                         * This will usually be a floppy disk. This size makes
                         * sure that one fat entry will not be split across
                         * multiple blocks.
                         */
                        pmp->pm_fatmask = FAT12_MASK;
                        pmp->pm_fatmult = 3;
                        pmp->pm_fatdiv = 2;
                } else {
                        pmp->pm_fatmask = FAT16_MASK;
                        pmp->pm_fatmult = 2;
                        pmp->pm_fatdiv = 1;
                }
        }

        clusters = (pmp->pm_fatsize / pmp->pm_fatmult) * pmp->pm_fatdiv;
        if (pmp->pm_maxcluster >= clusters) {
                kprintf("Warning: number of clusters (%ld) exceeds FAT "
                    "capacity (%ld)\n", pmp->pm_maxcluster + 1, clusters);
                pmp->pm_maxcluster = clusters - 1;
        }


        if (FAT12(pmp))
                pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
        else
                pmp->pm_fatblocksize = MSDOSFS_DFLTBSIZE;

        pmp->pm_fatblocksec = pmp->pm_fatblocksize / DEV_BSIZE;
        pmp->pm_bnshift = DEV_BSHIFT;

        /*
         * Compute mask and shift value for isolating cluster relative byte
         * offsets and cluster numbers from a file offset.
         */
        pmp->pm_bpcluster = SecPerClust * DEV_BSIZE;
        pmp->pm_crbomask = pmp->pm_bpcluster - 1;
        pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;

        /*
         * Check for valid cluster size
         * must be a power of 2
         */
        if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
                error = EINVAL;
                goto error_exit;
        }

        /*
         * Release the bootsector buffer.
         */
        brelse(bp);
        bp = NULL;

        /*
         * Check FSInfo.
         */
        if (pmp->pm_fsinfo) {
                struct fsinfo *fp;

                if ((error = bread(devvp, de_bntodoff(pmp, pmp->pm_fsinfo), fsi_size(pmp), &bp)) != 0)
                        goto error_exit;
                fp = (struct fsinfo *)bp->b_data;
                if (!bcmp(fp->fsisig1, "RRaA", 4)
                    && !bcmp(fp->fsisig2, "rrAa", 4)
                    && !bcmp(fp->fsisig3, "\0\0\125\252", 4)
                    && !bcmp(fp->fsisig4, "\0\0\125\252", 4)) {
                        pmp->pm_nxtfree = getulong(fp->fsinxtfree);
                        if (pmp->pm_nxtfree == 0xffffffff)
                                pmp->pm_nxtfree = CLUST_FIRST;
                } else
                        pmp->pm_fsinfo = 0;
                brelse(bp);
                bp = NULL;
        }

        /*
         * Check and validate (or perhaps invalidate?) the fsinfo structure?
         */
        if (pmp->pm_fsinfo && pmp->pm_nxtfree > pmp->pm_maxcluster) {
                kprintf(
                "Next free cluster in FSInfo (%lu) exceeds maxcluster (%lu)\n",
                    pmp->pm_nxtfree, pmp->pm_maxcluster);
                error = EINVAL;
                goto error_exit;
        }

        /*
         * Allocate memory for the bitmap of allocated clusters, and then
         * fill it in.
         */
        pmp->pm_inusemap = kmalloc(((pmp->pm_maxcluster + N_INUSEBITS - 1)
                                   / N_INUSEBITS)
                                  * sizeof(*pmp->pm_inusemap),
                                  M_MSDOSFSFAT, M_WAITOK);

        /*
         * fillinusemap() needs pm_devvp.
         */
        pmp->pm_dev = dev;
        pmp->pm_devvp = devvp;

        /*
         * Have the inuse map filled in.
         */
        if ((error = fillinusemap(pmp)) != 0)
                goto error_exit;

        /*
         * If they want fat updates to be synchronous then let them suffer
         * the performance degradation in exchange for the on disk copy of
         * the fat being correct just about all the time.  I suppose this
         * would be a good thing to turn on if the kernel is still flakey.
         */
        if (mp->mnt_flag & MNT_SYNCHRONOUS)
                pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;

        /*
         * Finish up.
         */
        if (ronly)
                pmp->pm_flags |= MSDOSFSMNT_RONLY;
        else
                pmp->pm_fmod = 1;
        mp->mnt_data = (qaddr_t) pmp;
        mp->mnt_stat.f_fsid.val[0] = dev2udev(dev);
        mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
        mp->mnt_flag |= MNT_LOCAL;
        vfs_add_vnodeops(mp, &msdosfs_vnode_vops, &mp->mnt_vn_norm_ops);
        dev->si_mountpoint = mp;

        return 0;

error_exit:
        if (bp)
                brelse(bp);
        VOP_CLOSE(devvp, ronly ? FREAD : FREAD | FWRITE);
        if (pmp) {
                if (pmp->pm_inusemap)
                        kfree(pmp->pm_inusemap, M_MSDOSFSFAT);
                kfree(pmp, M_MSDOSFSMNT);
                mp->mnt_data = (qaddr_t)0;
        }
        return (error);
}

/*
 * Unmount the filesystem described by mp.
 */
static int
msdosfs_unmount(struct mount *mp, int mntflags)
{
        struct msdosfsmount *pmp;
        int error, flags;

        flags = 0;
        if (mntflags & MNT_FORCE)
                flags |= FORCECLOSE;
        error = vflush(mp, 0, flags);
        if (error)
                return error;
        pmp = VFSTOMSDOSFS(mp);
        pmp->pm_devvp->v_rdev->si_mountpoint = NULL;
#ifdef MSDOSFS_DEBUG
        {
                struct vnode *vp = pmp->pm_devvp;

                kprintf("msdosfs_umount(): just before calling VOP_CLOSE()\n");
                kprintf("flag %08x, sysrefs %d, writecount %d, auxrefs %d\n",
                    vp->v_flag, vp->v_sysref.refcnt,
                    vp->v_writecount, vp->v_auxrefs);
                kprintf("mount %p, op %p\n", vp->v_mount, vp->v_ops);
                kprintf("mount %p\n", vp->v_mount);
                kprintf("cleanblkhd %p, dirtyblkhd %p, numoutput %d, type %d\n",
                    RB_ROOT(&vp->v_rbclean_tree),
                    RB_ROOT(&vp->v_rbdirty_tree),
                    vp->v_track_write.bk_active, vp->v_type);
                kprintf("union %p, tag %d, data[0] %08x, data[1] %08x\n",
                    vp->v_socket, vp->v_tag,
                    ((u_int *)vp->v_data)[0],
                    ((u_int *)vp->v_data)[1]);
        }
#endif
        error = VOP_CLOSE(pmp->pm_devvp,
                    (pmp->pm_flags&MSDOSFSMNT_RONLY) ? FREAD : FREAD | FWRITE);
        vrele(pmp->pm_devvp);
        kfree(pmp->pm_inusemap, M_MSDOSFSFAT);
        kfree(pmp, M_MSDOSFSMNT);
        mp->mnt_data = (qaddr_t)0;
        mp->mnt_flag &= ~MNT_LOCAL;
        return (error);
}

static int
msdosfs_root(struct mount *mp, struct vnode **vpp)
{
        struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
        struct denode *ndep;
        int error;

#ifdef MSDOSFS_DEBUG
        kprintf("msdosfs_root(); mp %p, pmp %p\n", mp, pmp);
#endif
        error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, &ndep);
        if (error)
                return (error);
        *vpp = DETOV(ndep);
        return (0);
}

static int
msdosfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
{
        struct msdosfsmount *pmp;

        pmp = VFSTOMSDOSFS(mp);
        sbp->f_bsize = pmp->pm_bpcluster;
        sbp->f_iosize = pmp->pm_bpcluster;
        sbp->f_blocks = pmp->pm_maxcluster + 1;
        sbp->f_bfree = pmp->pm_freeclustercount;
        sbp->f_bavail = pmp->pm_freeclustercount;
        sbp->f_files = pmp->pm_RootDirEnts;                     /* XXX */
        sbp->f_ffree = 0;       /* what to put in here? */
        if (sbp != &mp->mnt_stat) {
                sbp->f_type = mp->mnt_vfc->vfc_typenum;
                bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
        }
        strncpy(sbp->f_fstypename, mp->mnt_vfc->vfc_name, MFSNAMELEN);
        return (0);
}

struct scaninfo {
        int rescan;
        int allerror;
        int waitfor;
};

static int msdosfs_sync_scan(struct mount *mp, struct vnode *vp, void *data);

static int
msdosfs_sync(struct mount *mp, int waitfor)
{
        struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
        struct scaninfo scaninfo;
        int error;

        /*
         * If we ever switch to not updating all of the fats all the time,
         * this would be the place to update them from the first one.
         */
        if (pmp->pm_fmod != 0) {
                if (pmp->pm_flags & MSDOSFSMNT_RONLY)
                        panic("msdosfs_sync: rofs mod");
                else {
                        /* update fats here */
                }
        }
        /*
         * Write back each (modified) denode.
         */
        scaninfo.allerror = 0;
        scaninfo.rescan = 1;
        while (scaninfo.rescan) {
                scaninfo.rescan = 0;
                vmntvnodescan(mp, VMSC_GETVP|VMSC_NOWAIT, NULL, msdosfs_sync_scan, &scaninfo);
        }

        /*
         * Flush filesystem control info.
         */
        if (waitfor != MNT_LAZY) {
                vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY);
                if ((error = VOP_FSYNC(pmp->pm_devvp, waitfor)) != 0)
                        scaninfo.allerror = error;
                vn_unlock(pmp->pm_devvp);
        }
        return (scaninfo.allerror);
}

static int
msdosfs_sync_scan(struct mount *mp, struct vnode *vp, void *data)
{
        struct scaninfo *info = data;
        struct denode *dep;
        int error;

        dep = VTODE(vp);
        if (vp->v_type == VNON || vp->v_type == VBAD ||
            ((dep->de_flag &
            (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0 &&
            (RB_EMPTY(&vp->v_rbdirty_tree) || info->waitfor == MNT_LAZY))) {
                return(0);
        }
        if ((error = VOP_FSYNC(vp, info->waitfor)) != 0)
                info->allerror = error;
        return(0);
}

static int
msdosfs_fhtovp(struct mount *mp, struct vnode *rootvp,
               struct fid *fhp, struct vnode **vpp)
{
        struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
        struct defid *defhp = (struct defid *) fhp;
        struct denode *dep;
        int error;

        error = deget(pmp, defhp->defid_dirclust, defhp->defid_dirofs, &dep);
        if (error) {
                *vpp = NULLVP;
                return (error);
        }
        *vpp = DETOV(dep);
        return (0);
}

static int
msdosfs_checkexp(struct mount *mp, struct sockaddr *nam, int *exflagsp,
                 struct ucred **credanonp)
{
        struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
        struct netcred *np;

        np = vfs_export_lookup(mp, &pmp->pm_export, nam);
        if (np == NULL)
                return (EACCES);
        *exflagsp = np->netc_exflags;
        *credanonp = &np->netc_anon;
        return (0);
}

static int
msdosfs_vptofh(struct vnode *vp, struct fid *fhp)
{
        struct denode *dep;
        struct defid *defhp;

        dep = VTODE(vp);
        defhp = (struct defid *)fhp;
        defhp->defid_len = sizeof(struct defid);
        defhp->defid_dirclust = dep->de_dirclust;
        defhp->defid_dirofs = dep->de_diroffset;
        /* defhp->defid_gen = dep->de_gen; */
        return (0);
}

static struct vfsops msdosfs_vfsops = {
        .vfs_mount =            msdosfs_mount,
        .vfs_unmount =          msdosfs_unmount,
        .vfs_root =             msdosfs_root,
        .vfs_statfs =           msdosfs_statfs,
        .vfs_sync =             msdosfs_sync,
        .vfs_fhtovp =           msdosfs_fhtovp,
        .vfs_checkexp =         msdosfs_checkexp,
        .vfs_vptofh =           msdosfs_vptofh,
        .vfs_init =             msdosfs_init,
        .vfs_uninit =           msdosfs_uninit
};

VFS_SET(msdosfs_vfsops, msdos, 0);