path: root/sys/msdosfs/msdosfs_vfsops.c

/*	$NetBSD: msdosfs_vfsops.c,v 1.32 1995/09/09 19:38:08 ws Exp $	*/

/*-
 * Copyright (C) 1994 Wolfgang Solfrank.
 * Copyright (C) 1994 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/namei.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <miscfs/specfs/specdev.h> /* XXX */	/* defines v_rdev */
#include <sys/mount.h>
#include <sys/buf.h>
#include <sys/file.h>
#include <sys/disklabel.h>
#include <sys/ioctl.h>
#include <sys/malloc.h>

#include <msdosfs/bpb.h>
#include <msdosfs/bootsect.h>
#include <msdosfs/direntry.h>
#include <msdosfs/denode.h>
#include <msdosfs/msdosfsmount.h>
#include <msdosfs/fat.h>

/*
 * 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. 
 */
int
msdosfs_mount(mp, path, data, ndp, p)
	struct mount *mp;
	char *path;
	caddr_t data;
	struct nameidata *ndp;
	struct proc *p;
{
	struct vnode *devvp;	  /* vnode for blk device to mount */
	struct msdosfs_args args; /* will hold data from mount request */
	struct msdosfsmount *pmp; /* msdosfs specific mount control block */
	size_t size;
	int error, flags;
	mode_t accessmode;

	if (error = copyin(data, (caddr_t)&args, sizeof(struct msdosfs_args)))
		return (error);
	/*
	 * 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_ronly == 0 && (mp->mnt_flag & MNT_RDONLY)) {
			flags = WRITECLOSE;
			if (mp->mnt_flag & MNT_FORCE)
				flags |= FORCECLOSE;
			if (vfs_busy(mp))
				return (EBUSY);
			error = vflush(mp, NULLVP, flags);
			vfs_unbusy(mp);
		}
		if (!error && (mp->mnt_flag & MNT_RELOAD))
			/* not yet implemented */
			error = EOPNOTSUPP;
		if (error)
			return (error);
		if (pmp->pm_ronly && (mp->mnt_flag & MNT_WANTRDWR)) {
			/*
			 * If upgrade to read-write by non-root, then verify
			 * that user has necessary permissions on the device.
			 */
			if (p->p_ucred->cr_uid != 0) {
				devvp = pmp->pm_devvp;
				VOP_LOCK(devvp);
				if (error = VOP_ACCESS(devvp, VREAD | VWRITE,
				    p->p_ucred, p)) {
					VOP_UNLOCK(devvp);
					return (error);
				}
				VOP_UNLOCK(devvp);
			}
			pmp->pm_ronly = 0;
		}
		if (args.fspec == 0) {
			/*
			 * 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.
	 */
	NDINIT(ndp, LOOKUP, FOLLOW, UIO_USERSPACE, args.fspec, p);
	if (error = namei(ndp))
		return (error);
	devvp = ndp->ni_vp;

	if (devvp->v_type != VBLK) {
		vrele(devvp);
		return (ENOTBLK);
	}
	if (major(devvp->v_rdev) >= nblkdev) {
		vrele(devvp);
		return (ENXIO);
	}
	/*
	 * If mount by non-root, then verify that user has necessary
	 * permissions on the device.
	 */
	if (p->p_ucred->cr_uid != 0) {
		accessmode = VREAD;
		if ((mp->mnt_flag & MNT_RDONLY) == 0)
			accessmode |= VWRITE;
		VOP_LOCK(devvp);
		if (error = VOP_ACCESS(devvp, accessmode, p->p_ucred, p)) {
			vput(devvp);
			return (error);
		}
		VOP_UNLOCK(devvp);
	}
	if ((mp->mnt_flag & MNT_UPDATE) == 0)
		error = msdosfs_mountfs(devvp, mp, p);
	else {
		if (devvp != pmp->pm_devvp)
			error = EINVAL;	/* needs translation */
		else
			vrele(devvp);
	}
	if (error) {
		vrele(devvp);
		return (error);
	}
	pmp = VFSTOMSDOSFS(mp);
	pmp->pm_gid = args.gid;
	pmp->pm_uid = args.uid;
	pmp->pm_mask = args.mask;
	(void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size);
	bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size);
	(void) copyinstr(args.fspec, mp->mnt_stat.f_mntfromname, MNAMELEN - 1,
	    &size);
	bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
#ifdef MSDOSFS_DEBUG
	printf("msdosfs_mount(): mp %x, pmp %x, inusemap %x\n", mp, pmp, pmp->pm_inusemap);
#endif
	return (0);
}

int
msdosfs_mountfs(devvp, mp, p)
	struct vnode *devvp;
	struct mount *mp;
	struct proc *p;
{
	struct msdosfsmount *pmp;
	struct buf *bp;
	dev_t dev = devvp->v_rdev;
	struct partinfo dpart;
	union bootsector *bsp;
	struct byte_bpb33 *b33;
	struct byte_bpb50 *b50;
	extern struct vnode *rootvp;
	int	ronly, error;
#ifdef	atari
	int	bsize, dtype, tmp;
#endif	/* !atari */

	/*
	 * Disallow multiple mounts of the same device.
	 * Disallow mounting of a device that is currently in use
	 * (except for root, which might share swap device for miniroot).
	 * Flush out any old buffers remaining from a previous use.
	 */
	if (error = vfs_mountedon(devvp))
		return (error);
	if (vcount(devvp) > 1 && devvp != rootvp)
		return (EBUSY);
	if (error = vinvalbuf(devvp, V_SAVE, p->p_ucred, p, 0, 0))
		return (error);

	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
	if (error = VOP_OPEN(devvp, ronly ? FREAD : FREAD|FWRITE, FSCRED, p))
		return (error);
#ifdef	atari
	bp  = NULL; /* both used in error_exit */
	pmp = NULL;
	/*
	 * We need the disklabel to calculate the size of a FAT entry later on.
	 * Also make sure the partition contains a filesystem of type FS_MSDOS.
	 * This doesn't work for floppies, so we have to check for them too.
	 *
	 * At least some parts of the msdos fs driver seem to assume that the
	 * size of a disk block will always be 512 bytes. Let's check it...
	 */
	if (error = VOP_IOCTL(devvp, DIOCGPART, (caddr_t)&dpart, FREAD, NOCRED, p))
		goto error_exit;
	tmp   = dpart.part->p_fstype;
	dtype = dpart.disklab->d_type;
	bsize = dpart.disklab->d_secsize;
	if (bsize != 512 || (dtype != DTYPE_FLOPPY && tmp != FS_MSDOS)) {
		error = EINVAL;
		goto error_exit;
	}
#else	/* !atari */

	/*
	 * Read the boot sector of the filesystem, and then check the boot
	 * signature.  If not a dos boot sector then error out.
	 */
	bp = NULL;
	pmp = NULL;
#endif	/* !atari */
	if (error = bread(devvp, 0, 512, NOCRED, &bp))
		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;
#ifdef MSDOSFS_CHECKSIG
	if (bsp->bs50.bsBootSectSig != BOOTSIG) {
		error = EINVAL;
		goto error_exit;
	}
#endif

	pmp = malloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK);
	bzero((caddr_t)pmp, sizeof *pmp);
	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.
	 */
	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
	pmp->pm_SectPerClust = b50->bpbSecPerClust;
	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);
#ifdef	atari
	/*
	 * Meaningless on  a gemdos fs. This kind of information
	 * should be extracted from the disklabel structure.
	 */
	pmp->pm_SecPerTrack = 1;	/* anything between 1 and  63 */
	pmp->pm_Heads = 1;		/* anything between 1 and 255 */
	pmp->pm_Media = 0;		/* unused, any value will do  */
#else	/* !atari */
	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
	pmp->pm_Heads = getushort(b50->bpbHeads);
	pmp->pm_Media = b50->bpbMedia;

	/* XXX - We should probably check more values here */
    	if (!pmp->pm_BytesPerSec || !pmp->pm_SectPerClust ||
	    pmp->pm_Heads > 255 || pmp->pm_SecPerTrack > 63) {
		error = EINVAL;
		goto error_exit;
	}
#endif	/* !atari */

	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;
	}
#ifdef	atari
	/*
	 * 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 ( pmp->pm_BytesPerSec < bsize
	  || pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1)
	  || !pmp->pm_SectPerClust
	  || pmp->pm_SectPerClust & (pmp->pm_SectPerClust - 1)
	  || !pmp->pm_HugeSectors
	  || pmp->pm_HugeSectors * pmp->pm_BytesPerSec
				> dpart.part->p_size * bsize) {
		error = EINVAL;
		goto error_exit;
	}
	/*
	 * XXX - Many parts of the msdos fs driver seem to assume that
	 * the number of bytes per logical sector (BytesPerSec) will
	 * always be the same as the number of bytes per disk block
	 * Let's pretend it is.
	 */
	tmp = pmp->pm_BytesPerSec / bsize;
	pmp->pm_BytesPerSec = bsize;
	pmp->pm_SectPerClust *= tmp;
	pmp->pm_HugeSectors *= tmp;
	pmp->pm_HiddenSects *= tmp;
	pmp->pm_ResSectors *= tmp;
	pmp->pm_Sectors *= tmp;
	pmp->pm_FATsecs *= tmp;
#endif	/* atari */
	pmp->pm_fatblk = pmp->pm_ResSectors;
	pmp->pm_rootdirblk = pmp->pm_fatblk +
	    (pmp->pm_FATs * pmp->pm_FATsecs);
#ifdef	atari
	tmp = pmp->pm_RootDirEnts * sizeof(struct direntry);
	tmp += pmp->pm_BytesPerSec - 1;
	tmp /= pmp->pm_BytesPerSec;
	pmp->pm_rootdirsize = tmp;	/* in sectors */
#else	/* !atari */
	pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry))
	    /
	    pmp->pm_BytesPerSec;/* in sectors */
#endif	/* !atari */
	pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
	pmp->pm_nmbrofclusters = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
	    pmp->pm_SectPerClust;
	pmp->pm_maxcluster = pmp->pm_nmbrofclusters + 1;
	pmp->pm_fatsize = pmp->pm_FATsecs * pmp->pm_BytesPerSec;
#ifdef	atari
	if (dtype == DTYPE_FLOPPY) {
		pmp->pm_fatentrysize = 12;
		pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
	} else {
		pmp->pm_fatentrysize = 16;
		pmp->pm_fatblocksize = MAXBSIZE;
	}
#else	/* !atari */
	if (FAT12(pmp))
		/*
		 * This will usually be a floppy disk. This size makes sure
		 * that one fat entry will not be split across multiple
		 * blocks.
		 */
		pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
	else
		/*
		 * This will usually be a hard disk. Reading or writing one
		 * block should be quite fast.
		 */
		pmp->pm_fatblocksize = MAXBSIZE;
#endif	/* !atari */
	pmp->pm_fatblocksec = pmp->pm_fatblocksize / pmp->pm_BytesPerSec;

#ifdef	atari
	/*
	 * Be prepared for block size != 512
	 */
	pmp->pm_brbomask = bsize - 1;
	for (tmp = 0; bsize >>= 1; ++tmp)
		;
	pmp->pm_bnshift = tmp;
	/*
	 * Compute mask and shift value for isolating cluster relative
	 * byte offsets and cluster numbers from a file offset. We
	 * already know that the number of sectors per cluster is
	 * > 0 and a power of 2.
	 */
	bsize = pmp->pm_SectPerClust * pmp->pm_BytesPerSec;
	pmp->pm_crbomask  = bsize - 1;
	pmp->pm_bpcluster = bsize;
	for (tmp = 0; bsize >>= 1; ++tmp)
		;
	pmp->pm_cnshift = tmp;

#else	/* !atari */
	/*
	 * Compute mask and shift value for isolating cluster relative byte
	 * offsets and cluster numbers from a file offset.
	 */
	pmp->pm_bpcluster = pmp->pm_SectPerClust * pmp->pm_BytesPerSec;
	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;
	if (pmp->pm_cnshift < 0
	    || pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
		error = EINVAL;
		goto error_exit;
	}

	pmp->pm_brbomask = 0x01ff;	/* 512 byte blocks only (so far) */
	pmp->pm_bnshift = 9;	/* shift right 9 bits to get bn */
#endif	/* !atari */

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

	/*
	 * Allocate memory for the bitmap of allocated clusters, and then
	 * fill it in.
	 */
	pmp->pm_inusemap = malloc(((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))
		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.
	 */
	pmp->pm_waitonfat = mp->mnt_flag & MNT_SYNCHRONOUS;

	/*
	 * Finish up.
	 */
	pmp->pm_ronly = ronly;
	if (ronly == 0)
		pmp->pm_fmod = 1;
	mp->mnt_data = (qaddr_t)pmp;
        mp->mnt_stat.f_fsid.val[0] = (long)dev;
        mp->mnt_stat.f_fsid.val[1] = makefstype(MOUNT_MSDOS);
	mp->mnt_flag |= MNT_LOCAL;
#ifdef QUOTA
	/*
	 * If we ever do quotas for DOS filesystems this would be a place
	 * to fill in the info in the msdosfsmount structure. You dolt,
	 * quotas on dos filesystems make no sense because files have no
	 * owners on dos filesystems. of course there is some empty space
	 * in the directory entry where we could put uid's and gid's.
	 */
#endif
	devvp->v_specflags |= SI_MOUNTEDON;

	return (0);

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

int
msdosfs_start(mp, flags, p)
	struct mount *mp;
	int flags;
	struct proc *p;
{

	return (0);
}

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

	flags = 0;
	if (mntflags & MNT_FORCE)
		flags |= FORCECLOSE;
#ifdef QUOTA
#endif
	if (error = vflush(mp, NULLVP, flags))
		return (error);
	pmp = VFSTOMSDOSFS(mp);
	pmp->pm_devvp->v_specflags &= ~SI_MOUNTEDON;
#ifdef MSDOSFS_DEBUG
	printf("msdosfs_umount(): just before calling VOP_CLOSE()\n");
	printf("flag %08x, usecount %d, writecount %d, holdcnt %d\n",
	    vp->v_flag, vp->v_usecount, vp->v_writecount, vp->v_holdcnt);
	printf("lastr %d, id %d, mount %08x, op %08x\n",
	    vp->v_lastr, vp->v_id, vp->v_mount, vp->v_op);
	printf("freef %08x, freeb %08x, mountf %08x, mountb %08x\n",
	    vp->v_freef, vp->v_freeb, vp->v_mountf, vp->v_mountb);
	printf("cleanblkhd %08x, dirtyblkhd %08x, numoutput %d, type %d\n",
	    vp->v_cleanblkhd, vp->v_dirtyblkhd, vp->v_numoutput, vp->v_type);
	printf("union %08x, tag %d, data[0] %08x, data[1] %08x\n",
	    vp->v_socket, vp->v_tag, vp->v_data[0], vp->v_data[1]);
#endif
	error = VOP_CLOSE(pmp->pm_devvp, pmp->pm_ronly ? FREAD : FREAD|FWRITE,
	    NOCRED, p);
	vrele(pmp->pm_devvp);
	free(pmp->pm_inusemap, M_MSDOSFSFAT);
	free(pmp, M_MSDOSFSMNT);
	mp->mnt_data = (qaddr_t)0;
	mp->mnt_flag &= ~MNT_LOCAL;
	return (error);
}

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

#ifdef MSDOSFS_DEBUG
	printf("msdosfs_root(); mp %08x, pmp %08x, ndep %08x, vp %08x\n",
	    mp, pmp, ndep, DETOV(ndep));
#endif
	if (error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, NULL, &ndep))
		return (error);
	*vpp = DETOV(ndep);
	return (0);
}

int
msdosfs_quotactl(mp, cmds, uid, arg, p)
	struct mount *mp;
	int cmds;
	uid_t uid;
	caddr_t arg;
	struct proc *p;
{

#ifdef QUOTA
	return (EOPNOTSUPP);
#else
	return (EOPNOTSUPP);
#endif
}

int
msdosfs_statfs(mp, sbp, p)
	struct mount *mp;
	struct statfs *sbp;
	struct proc *p;
{
	struct msdosfsmount *pmp;

	pmp = VFSTOMSDOSFS(mp);
#ifdef COMPAT_09
	sbp->f_type = 4;
#else
	sbp->f_type = 0;
#endif
	sbp->f_bsize = pmp->pm_bpcluster;
	sbp->f_iosize = pmp->pm_bpcluster;
	sbp->f_blocks = pmp->pm_nmbrofclusters;
	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) {
		bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
		bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
	}
	strncpy(sbp->f_fstypename, mp->mnt_op->vfs_name, MFSNAMELEN);
	return (0);
}

int
msdosfs_sync(mp, waitfor, cred, p)
	struct mount *mp;
	int waitfor;
	struct ucred *cred;
	struct proc *p;
{
	struct vnode *vp;
	struct denode *dep;
	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
	int error, allerror = 0;

	/*
	 * 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_ronly != 0)
			panic("msdosfs_sync: rofs mod");
		else {
			/* update fats here */
		}
	/*
	 * Write back each (modified) denode.
	 */
loop:
	for (vp = mp->mnt_vnodelist.lh_first;
	     vp != NULL;
	     vp = vp->v_mntvnodes.le_next) {
		/*
		 * If the vnode that we are about to sync is no longer
		 * assoicated with this mount point, start over.
		 */
		if (vp->v_mount != mp)
			goto loop;
		if (VOP_ISLOCKED(vp))
			continue;
		dep = VTODE(vp);
		if ((dep->de_flag & DE_UPDATE) == 0 &&
		    vp->v_dirtyblkhd.lh_first == NULL)
			continue;
		if (vget(vp, 1))
			goto loop;
		if (error = VOP_FSYNC(vp, cred, waitfor, p))
			allerror = error;
		vput(vp);
	}
	/*
	 * Force stale file system control information to be flushed.
	 */
	if (error = VOP_FSYNC(pmp->pm_devvp, cred, waitfor, p))
		allerror = error;
#ifdef QUOTA
#endif
	return (allerror);
}

int
msdosfs_fhtovp(mp, fhp, nam, vpp, exflagsp, credanonp)
	struct mount *mp;
	struct fid *fhp;
	struct mbuf *nam;
	struct vnode **vpp;
	int *exflagsp;
	struct ucred **credanonp;
{
	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
	struct defid *defhp = (struct defid *) fhp;
	struct denode *dep;
	struct netcred *np;
	int error;

	np = vfs_export_lookup(mp, &pmp->pm_export, nam);
	if (np == NULL)
		return (EACCES);
	error = deget(pmp, defhp->defid_dirclust, defhp->defid_dirofs,
	    NULL, &dep);
	if (error) {
		*vpp = NULLVP;
		return (error);
	}
	*vpp = DETOV(dep);
	*exflagsp = np->netc_exflags;
	*credanonp = &np->netc_anon;
	return (0);
}

int
msdosfs_vptofh(vp, fhp)
	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);
}

int
msdosfs_vget(mp, ino, vpp)
	struct mount *mp;
	ino_t ino;
	struct vnode **vpp;
{

	return (EOPNOTSUPP);
}

struct vfsops msdosfs_vfsops = {
	MOUNT_MSDOS,
	msdosfs_mount,
	msdosfs_start,
	msdosfs_unmount,
	msdosfs_root,
	msdosfs_quotactl,
	msdosfs_statfs,
	msdosfs_sync,
	msdosfs_vget,
	msdosfs_fhtovp,
	msdosfs_vptofh,
	msdosfs_init
};