/* $FreeBSD$ */
/*      $NetBSD: msdosfs_vfsops.c,v 1.51 1997/11/17 15:36:58 ws Exp $   */

/*-
 * SPDX-License-Identifier: BSD-4-Clause
 *
 * 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/iconv.h>
#include <sys/mount.h>
#include <sys/buf.h>
#include <sys/fcntl.h>
#include <sys/malloc.h>
#include <sys/stat.h>
#include <vm/vm_zone.h>

#include <sys/buf2.h>

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

extern struct vop_ops msdosfs_vnode_vops;
struct iconv_functions *msdosfs_iconv;

#define ENCODING_UNICODE        "UTF-16BE"
#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 mountmsdosfs(struct vnode *devvp, struct mount *mp,
    struct msdosfs_args *argp);
static int msdosfs_root(struct mount *, struct vnode **);
static int msdosfs_statfs(struct mount *, struct statfs *, struct ucred *);
static int msdosfs_unmount(struct mount *, int);

static int
update_mp(struct mount *mp, struct msdosfs_args *argp)
{
        struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
        int error;
        char cs_local[ICONV_CSNMAXLEN];
        char cs_dos[ICONV_CSNMAXLEN];

        pmp->pm_gid = argp->gid;
        pmp->pm_uid = argp->uid;
        pmp->pm_mask = argp->mask & ALLPERMS;
        pmp->pm_dirmask = argp->dirmask & ALLPERMS;
        pmp->pm_flags |= argp->flags & MSDOSFSMNT_MNTOPT;

        if (pmp->pm_flags & MSDOSFSMNT_KICONV && msdosfs_iconv) {
                memcpy(cs_local, argp->cs_local, sizeof(cs_local));
                memcpy(cs_dos, argp->cs_dos, sizeof(cs_dos));
                kprintf("local: %s dos: %s\n",argp->cs_local, argp->cs_dos);
                error = msdosfs_iconv->open(cs_local, ENCODING_UNICODE,
                                            &pmp->pm_w2u);
                if(error)
                        return error;
                error = msdosfs_iconv->open(ENCODING_UNICODE, cs_local,
                                            &pmp->pm_u2w);
                if(error)
                        return error;
                error = msdosfs_iconv->open(cs_dos, cs_local, &pmp->pm_u2d);
                if(error)
                        return error;
                error = msdosfs_iconv->open(cs_local, cs_dos, &pmp->pm_d2u);
                if(error)
                        return error;
        }

        if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
                pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
        else
                pmp->pm_flags |= MSDOSFSMNT_LONGNAME;
        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 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;
                                vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
                                VOP_OPEN(devvp, FREAD, FSCRED, NULL);
                                VOP_CLOSE(devvp, FREAD|FWRITE, NULL);
                                vn_unlock(devvp);
                                pmp->pm_flags |= MSDOSFSMNT_RONLY;
                        }
                }
                if (!error && (mp->mnt_flag & MNT_RELOAD))
                        error = EOPNOTSUPP; /* not yet implemented */
                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_EACCESS(devvp, VREAD | VWRITE,
                                                    cred);
                                if (error) {
                                        vn_unlock(devvp);
                                        return (error);
                                }
                        }
                        VOP_OPEN(devvp, FREAD|FWRITE, FSCRED, NULL);
                        VOP_CLOSE(devvp, FREAD, NULL);
                        vn_unlock(devvp);
                        pmp->pm_flags &= ~MSDOSFSMNT_RONLY;
                }
                if (args.fspec == NULL) {
#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 disk 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_EACCESS(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) {
                if ((mp->mnt_flag & MNT_UPDATE) == 0)
                        msdosfs_unmount(mp, MNT_FORCE);
                return error;
        }

        copyinstr(args.fspec, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, &size);
        memset(mp->mnt_stat.f_mntfromname + size, 0, 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;
        uint8_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 (vcount(devvp) > 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: 8192 is a magic size that works for ffs.
         */
        error = bread(devvp, 0, 8192, &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.bsBPB;

#ifndef MSDOSFS_NOCHECKSIG
        if (bsp->bs50.bsBootSectSig0 != BOOTSIG0 ||
            bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
                error = EINVAL;
                goto error_exit;
        }
#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);
        if (pmp->pm_BytesPerSec < DEV_BSIZE) {
                error = EINVAL;
                goto error_exit;
        }
        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;

        /*
         * 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 == 0 || SecPerClust == 0) {
                error = EINVAL;
                goto error_exit;
        }

        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_FATsecs != 0 || getushort(b710->bpbFSVers) != 0) {
                        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) != 0)
                        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
         * - number of FAT sectors: >= 1
         */
        if (SecPerClust == 0 || (SecPerClust & (SecPerClust - 1)) != 0 ||
            pmp->pm_BytesPerSec < DEV_BSIZE ||
            (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1)) != 0 ||
            pmp->pm_HugeSectors == 0 || pmp->pm_FATsecs == 0 ||
            SecPerClust * pmp->pm_BlkPerSec > MAXBSIZE / DEV_BSIZE) {
                error = EINVAL;
                goto error_exit;
        }

        if ((off_t)pmp->pm_HugeSectors * pmp->pm_BytesPerSec <
            pmp->pm_HugeSectors /* overflow */) {
                /* XXX FreeBSD also checks media size in above */
                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 = howmany(pmp->pm_RootDirEnts *
                    sizeof(struct direntry), DEV_BSIZE); /* in blocks */
                pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
        }

        if (pmp->pm_HugeSectors <= pmp->pm_firstcluster) {
                error = EINVAL;
                goto error_exit;
        }
        pmp->pm_maxcluster = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
            SecPerClust + 1;

        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_FATsecs * DEV_BSIZE) / 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 * 512;
        else
                pmp->pm_fatblocksize = PAGE_SIZE;
        pmp->pm_fatblocksize = roundup(pmp->pm_fatblocksize,
            pmp->pm_BytesPerSec);
        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)) != 0) {
                error = EINVAL;
                goto error_exit;
        }

        /*
         * Release the bootsector buffer.
         */
        bp->b_flags |= B_RELBUF;
        brelse(bp);
        bp = NULL;

        /*
         * Check the fsinfo sector if we have one.  Silently fix up our
         * in-core copy of fp->fsinxtfree if it is unknown (0xffffffff)
         * or too large.  Ignore fp->fsinfree for now, since we need to
         * read the entire FAT anyway to fill the inuse map.
         */
        if (pmp->pm_fsinfo) {
                struct fsinfo *fp;

                if ((error = bread(devvp, de_bn2doff(pmp, pmp->pm_fsinfo),
                    pmp->pm_BytesPerSec, &bp)) != 0)
                        goto error_exit;
                fp = (struct fsinfo *)bp->b_data;
                if (!memcmp(fp->fsisig1, "RRaA", 4) &&
                    !memcmp(fp->fsisig2, "rrAa", 4) &&
                    !memcmp(fp->fsisig3, "\0\0\125\252", 4)) {
                        pmp->pm_nxtfree = getulong(fp->fsinxtfree);
                        if (pmp->pm_nxtfree > pmp->pm_maxcluster)
                                pmp->pm_nxtfree = CLUST_FIRST;
                } else
                        pmp->pm_fsinfo = 0;
                bp->b_flags |= B_RELBUF;
                brelse(bp);
                bp = NULL;
        }

        /*
         * Finish initializing pmp->pm_nxtfree (just in case the first few
         * sectors aren't properly reserved in the FAT).  This completes
         * the fixup for fp->fsinxtfree, and fixes up the zero-initialized
         * value if there is no fsinfo.  We will use pmp->pm_nxtfree
         * internally even if there is no fsinfo.
         */
        if (pmp->pm_nxtfree < CLUST_FIRST)
                pmp->pm_nxtfree = CLUST_FIRST;

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

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

        /*
         * Have the inuse map filled in.
         */
        MSDOSFS_LOCK_MP(pmp);
        error = fillinusemap(pmp);
        MSDOSFS_UNLOCK_MP(pmp);
        if (error != 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] = devid_from_dev(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 != NULL) {
                bp->b_flags |= B_RELBUF;
                brelse(bp);
        }
        vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
        VOP_CLOSE(devvp, ronly ? FREAD : FREAD | FWRITE, NULL);
        vn_unlock(devvp);
        if (pmp != NULL) {
                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;
#ifdef MSDOSFS_DEBUG
        struct vnode *vp;
#endif
        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;

        if (pmp->pm_flags & MSDOSFSMNT_KICONV && msdosfs_iconv) {
                if (pmp->pm_w2u)
                        msdosfs_iconv->close(pmp->pm_w2u);
                if (pmp->pm_u2w)
                        msdosfs_iconv->close(pmp->pm_u2w);
                if (pmp->pm_d2u)
                        msdosfs_iconv->close(pmp->pm_d2u);
                if (pmp->pm_u2d)
                        msdosfs_iconv->close(pmp->pm_u2d);
        }

#ifdef MSDOSFS_DEBUG
        vp = pmp->pm_devvp;
        kprintf("msdosfs_umount(): just before calling VOP_CLOSE()\n");
        kprintf("flag %08x, refcnt 0x%08x, writecount %d, auxrefs 0x%08x\n",
                vp->v_flag, vp->v_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),
                bio_track_active(&vp->v_track_write), 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

        vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY);
        error = VOP_CLOSE(pmp->pm_devvp,
                    pmp->pm_flags & MSDOSFSMNT_RONLY ? FREAD : FREAD | FWRITE,
                    NULL);
        vn_unlock(pmp->pm_devvp);
        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;

        mprintf("msdosfs_root(); mp %p, pmp %p\n", mp, pmp);
        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;
                memcpy(sbp->f_mntfromname, mp->mnt_stat.f_mntfromname, MNAMELEN);
        }
        strncpy(sbp->f_fstypename, mp->mnt_vfc->vfc_name, MFSNAMELEN);
        return (0);
}

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

        pmp = VFSTOMSDOSFS(mp);
        sbp->f_bsize = pmp->pm_bpcluster;
        sbp->f_frsize = 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_vstat) {
                sbp->f_type = mp->mnt_vfc->vfc_typenum;
        }
        return (0);
}

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

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

/*
 * If we have an FSInfo block, update it.
 */
static int
msdosfs_fsiflush(struct msdosfsmount *pmp, int waitfor)
{
        struct fsinfo *fp;
        struct buf *bp;
        int error;

        MSDOSFS_LOCK_MP(pmp);
        if (pmp->pm_fsinfo == 0 || (pmp->pm_flags & MSDOSFS_FSIMOD) == 0) {
                error = 0;
                goto unlock;
        }
        error = bread(pmp->pm_devvp, de_bn2doff(pmp, pmp->pm_fsinfo),
            pmp->pm_BytesPerSec, &bp);
        if (error != 0) {
                brelse(bp);
                goto unlock;
        }

        fp = (struct fsinfo *)bp->b_data;
        putulong(fp->fsinfree, pmp->pm_freeclustercount);
        putulong(fp->fsinxtfree, pmp->pm_nxtfree);
        pmp->pm_flags &= ~MSDOSFS_FSIMOD;
        if (waitfor == MNT_WAIT)
                error = bwrite(bp);
        else
                bawrite(bp);
unlock:
        MSDOSFS_UNLOCK_MP(pmp);
        return (error);
}

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) == 0) {
                vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY);
                if ((error = VOP_FSYNC(pmp->pm_devvp, waitfor, 0)) != 0)
                        scaninfo.allerror = error;
                vn_unlock(pmp->pm_devvp);
        }

        error = msdosfs_fsiflush(pmp, waitfor);
        if (error != 0)
                scaninfo.allerror = error;
        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)) != 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_flags =            0,
        .vfs_mount =            msdosfs_mount,
        .vfs_root =             msdosfs_root,
        .vfs_statfs =           msdosfs_statfs,
        .vfs_statvfs =          msdosfs_statvfs,
        .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_unmount =          msdosfs_unmount,
};

VFS_SET(msdosfs_vfsops, msdos, 0);
MODULE_VERSION(msdos, 1);