xref: /openbsd/sys/msdosfs/msdosfs_vfsops.c (revision 097a140d)
1 /*	$OpenBSD: msdosfs_vfsops.c,v 1.94 2020/08/10 05:18:46 jsg Exp $	*/
2 /*	$NetBSD: msdosfs_vfsops.c,v 1.48 1997/10/18 02:54:57 briggs Exp $	*/
3 
4 /*-
5  * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
6  * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
7  * All rights reserved.
8  * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by TooLs GmbH.
21  * 4. The name of TooLs GmbH may not be used to endorse or promote products
22  *    derived from this software without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
25  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
29  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
30  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
31  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
32  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
33  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34  */
35 /*
36  * Written by Paul Popelka (paulp@uts.amdahl.com)
37  *
38  * You can do anything you want with this software, just don't say you wrote
39  * it, and don't remove this notice.
40  *
41  * This software is provided "as is".
42  *
43  * The author supplies this software to be publicly redistributed on the
44  * understanding that the author is not responsible for the correct
45  * functioning of this software in any circumstances and is not liable for
46  * any damages caused by this software.
47  *
48  * October 1992
49  */
50 
51 #include <sys/param.h>
52 #include <sys/systm.h>
53 #include <sys/namei.h>
54 #include <sys/proc.h>
55 #include <sys/kernel.h>
56 #include <sys/vnode.h>
57 #include <sys/lock.h>
58 #include <sys/specdev.h> /* XXX */	/* defines v_rdev */
59 #include <sys/mount.h>
60 #include <sys/buf.h>
61 #include <sys/fcntl.h>
62 #include <sys/disklabel.h>
63 #include <sys/ioctl.h>
64 #include <sys/malloc.h>
65 #include <sys/dirent.h>
66 #include <sys/disk.h>
67 #include <sys/dkio.h>
68 #include <sys/stdint.h>
69 
70 #include <msdosfs/bpb.h>
71 #include <msdosfs/bootsect.h>
72 #include <msdosfs/direntry.h>
73 #include <msdosfs/denode.h>
74 #include <msdosfs/msdosfsmount.h>
75 #include <msdosfs/fat.h>
76 
77 int msdosfs_mount(struct mount *, const char *, void *, struct nameidata *,
78 		       struct proc *);
79 int msdosfs_start(struct mount *, int, struct proc *);
80 int msdosfs_unmount(struct mount *, int, struct proc *);
81 int msdosfs_root(struct mount *, struct vnode **);
82 int msdosfs_statfs(struct mount *, struct statfs *, struct proc *);
83 int msdosfs_sync(struct mount *, int, int, struct ucred *, struct proc *);
84 int msdosfs_fhtovp(struct mount *, struct fid *, struct vnode **);
85 int msdosfs_vptofh(struct vnode *, struct fid *);
86 int msdosfs_check_export(struct mount *mp, struct mbuf *nam,
87 			      int *extflagsp, struct ucred **credanonp);
88 
89 int msdosfs_mountfs(struct vnode *, struct mount *, struct proc *,
90 			 struct msdosfs_args *);
91 
92 int msdosfs_sync_vnode(struct vnode *, void *);
93 
94 /*
95  * mp - path - addr in user space of mount point (ie /usr or whatever)
96  * data - addr in user space of mount params including the name of the block
97  * special file to treat as a filesystem.
98  */
99 int
100 msdosfs_mount(struct mount *mp, const char *path, void *data,
101     struct nameidata *ndp, struct proc *p)
102 {
103 	struct vnode *devvp;	  /* vnode for blk device to mount */
104 	struct msdosfs_args *args = data; /* will hold data from mount request */
105 	/* msdosfs specific mount control block */
106 	struct msdosfsmount *pmp = NULL;
107 	char fname[MNAMELEN];
108 	char fspec[MNAMELEN];
109 	int error, flags;
110 
111 	/*
112 	 * If updating, check whether changing from read-only to
113 	 * read/write; if there is no device name, that's all we do.
114 	 */
115 	if (mp->mnt_flag & MNT_UPDATE) {
116 		pmp = VFSTOMSDOSFS(mp);
117 		error = 0;
118 		if (!(pmp->pm_flags & MSDOSFSMNT_RONLY) &&
119 		    (mp->mnt_flag & MNT_RDONLY)) {
120 			mp->mnt_flag &= ~MNT_RDONLY;
121 			VFS_SYNC(mp, MNT_WAIT, 0, p->p_ucred, p);
122 			mp->mnt_flag |= MNT_RDONLY;
123 
124 			flags = WRITECLOSE;
125 			if (mp->mnt_flag & MNT_FORCE)
126 				flags |= FORCECLOSE;
127 			error = vflush(mp, NULLVP, flags);
128 			if (!error) {
129 				int force = 0;
130 
131 				pmp->pm_flags |= MSDOSFSMNT_RONLY;
132 				/* may be not supported, ignore error */
133 				VOP_IOCTL(pmp->pm_devvp, DIOCCACHESYNC,
134 				    &force, FWRITE, FSCRED, p);
135 			}
136 		}
137 		if (!error && (mp->mnt_flag & MNT_RELOAD))
138 			/* not yet implemented */
139 			error = EOPNOTSUPP;
140 		if (error)
141 			return (error);
142 		if ((pmp->pm_flags & MSDOSFSMNT_RONLY) &&
143 		    (mp->mnt_flag & MNT_WANTRDWR))
144 			pmp->pm_flags &= ~MSDOSFSMNT_RONLY;
145 
146 		if (args && args->fspec == NULL) {
147 			/*
148 			 * Process export requests.
149 			 */
150 			return (vfs_export(mp, &pmp->pm_export,
151 			    &args->export_info));
152 		}
153 		if (args == NULL)
154 			return (0);
155 	}
156 
157 	/*
158 	 * Not an update, or updating the name: look up the name
159 	 * and verify that it refers to a sensible block device.
160 	 */
161 	error = copyinstr(args->fspec, fspec, sizeof(fspec), NULL);
162 	if (error)
163 		goto error;
164 
165 	if (disk_map(fspec, fname, sizeof(fname), DM_OPENBLCK) == -1)
166 		bcopy(fspec, fname, sizeof(fname));
167 
168 	NDINIT(ndp, LOOKUP, FOLLOW, UIO_SYSSPACE, fname, p);
169 	if ((error = namei(ndp)) != 0)
170 		goto error;
171 
172 	devvp = ndp->ni_vp;
173 
174 	if (devvp->v_type != VBLK) {
175 		error = ENOTBLK;
176 		goto error_devvp;
177 	}
178 	if (major(devvp->v_rdev) >= nblkdev) {
179 		error = ENXIO;
180 		goto error_devvp;
181 	}
182 
183 	if ((mp->mnt_flag & MNT_UPDATE) == 0)
184 		error = msdosfs_mountfs(devvp, mp, p, args);
185 	else {
186 		if (devvp != pmp->pm_devvp)
187 			error = EINVAL;	/* XXX needs translation */
188 		else
189 			vrele(devvp);
190 	}
191 	if (error)
192 		goto error_devvp;
193 
194 	pmp = VFSTOMSDOSFS(mp);
195 	pmp->pm_gid = args->gid;
196 	pmp->pm_uid = args->uid;
197 	pmp->pm_mask = args->mask;
198 	pmp->pm_flags |= args->flags & MSDOSFSMNT_MNTOPT;
199 
200 	if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
201 		pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
202 	else if (!(pmp->pm_flags &
203 	    (MSDOSFSMNT_SHORTNAME | MSDOSFSMNT_LONGNAME))) {
204 		struct vnode *rvp;
205 
206 		/*
207 		 * Try to divine whether to support Win'95 long filenames
208 		 */
209 		if (FAT32(pmp))
210 		        pmp->pm_flags |= MSDOSFSMNT_LONGNAME;
211 		else {
212 		        if ((error = msdosfs_root(mp, &rvp)) != 0) {
213 			        msdosfs_unmount(mp, MNT_FORCE, p);
214 			        goto error;
215 			}
216 			pmp->pm_flags |= findwin95(VTODE(rvp))
217 			     ? MSDOSFSMNT_LONGNAME
218 			     : MSDOSFSMNT_SHORTNAME;
219 			vput(rvp);
220 		}
221 	}
222 
223 	if (pmp->pm_flags & MSDOSFSMNT_LONGNAME)
224 		mp->mnt_stat.f_namemax = WIN_MAXLEN;
225 	else
226 		mp->mnt_stat.f_namemax = 12;
227 
228 	bzero(mp->mnt_stat.f_mntonname, MNAMELEN);
229 	strlcpy(mp->mnt_stat.f_mntonname, path, MNAMELEN);
230 	bzero(mp->mnt_stat.f_mntfromname, MNAMELEN);
231 	strlcpy(mp->mnt_stat.f_mntfromname, fname, MNAMELEN);
232 	bzero(mp->mnt_stat.f_mntfromspec, MNAMELEN);
233 	strlcpy(mp->mnt_stat.f_mntfromspec, fspec, MNAMELEN);
234 	bcopy(args, &mp->mnt_stat.mount_info.msdosfs_args, sizeof(*args));
235 
236 #ifdef MSDOSFS_DEBUG
237 	printf("msdosfs_mount(): mp %p, pmp %p, inusemap %p\n", mp,
238 	    pmp, pmp->pm_inusemap);
239 #endif
240 
241 	return (0);
242 
243 error_devvp:
244 	vrele(devvp);
245 
246 error:
247 	return (error);
248 }
249 
250 int
251 msdosfs_mountfs(struct vnode *devvp, struct mount *mp, struct proc *p,
252     struct msdosfs_args *argp)
253 {
254 	struct msdosfsmount *pmp;
255 	struct buf *bp;
256 	dev_t dev = devvp->v_rdev;
257 	union bootsector *bsp;
258 	struct byte_bpb33 *b33;
259 	struct byte_bpb50 *b50;
260 	struct byte_bpb710 *b710;
261 	extern struct vnode *rootvp;
262 	u_int8_t SecPerClust;
263 	int	ronly, error, bmapsiz;
264 	uint32_t fat_max_clusters;
265 
266 	/*
267 	 * Disallow multiple mounts of the same device.
268 	 * Disallow mounting of a device that is currently in use
269 	 * (except for root, which might share swap device for miniroot).
270 	 * Flush out any old buffers remaining from a previous use.
271 	 */
272 	if ((error = vfs_mountedon(devvp)) != 0)
273 		return (error);
274 	if (vcount(devvp) > 1 && devvp != rootvp)
275 		return (EBUSY);
276 	vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
277 	error = vinvalbuf(devvp, V_SAVE, p->p_ucred, p, 0, INFSLP);
278 	VOP_UNLOCK(devvp);
279 	if (error)
280 		return (error);
281 
282 	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
283 	error = VOP_OPEN(devvp, ronly ? FREAD : FREAD|FWRITE, FSCRED, p);
284 	if (error)
285 		return (error);
286 
287 	bp  = NULL; /* both used in error_exit */
288 	pmp = NULL;
289 
290 	/*
291 	 * Read the boot sector of the filesystem, and then check the
292 	 * boot signature.  If not a dos boot sector then error out.
293 	 */
294 	if ((error = bread(devvp, 0, 4096, &bp)) != 0)
295 		goto error_exit;
296 	bsp = (union bootsector *)bp->b_data;
297 	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
298 	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
299 	b710 = (struct byte_bpb710 *)bsp->bs710.bsBPB;
300 
301 	pmp = malloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK | M_ZERO);
302 	pmp->pm_mountp = mp;
303 
304 	/*
305 	 * Compute several useful quantities from the bpb in the
306 	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
307 	 * the fields that are different between dos 5 and dos 3.3.
308 	 */
309 	SecPerClust = b50->bpbSecPerClust;
310 	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
311 	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
312 	pmp->pm_FATs = b50->bpbFATs;
313 	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
314 	pmp->pm_Sectors = getushort(b50->bpbSectors);
315 	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
316 	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
317 	pmp->pm_Heads = getushort(b50->bpbHeads);
318 	pmp->pm_Media = b50->bpbMedia;
319 
320 	/* Determine the number of DEV_BSIZE blocks in a MSDOSFS sector */
321 	pmp->pm_BlkPerSec = pmp->pm_BytesPerSec / DEV_BSIZE;
322 
323 	if (!pmp->pm_BytesPerSec || !SecPerClust) {
324 		error = EINVAL;
325 		goto error_exit;
326 	}
327 
328 	if (pmp->pm_Sectors == 0) {
329 		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
330 		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
331 	} else {
332 		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
333 		pmp->pm_HugeSectors = pmp->pm_Sectors;
334 	}
335 
336 	if (pmp->pm_RootDirEnts == 0) {
337 		if (pmp->pm_Sectors || pmp->pm_FATsecs ||
338 		    getushort(b710->bpbFSVers)) {
339 		        error = EINVAL;
340 			goto error_exit;
341 		}
342 		pmp->pm_fatmask = FAT32_MASK;
343 		pmp->pm_fatmult = 4;
344 		pmp->pm_fatdiv = 1;
345 		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);
346 		if (getushort(b710->bpbExtFlags) & FATMIRROR)
347 		        pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
348 		else
349 		        pmp->pm_flags |= MSDOSFS_FATMIRROR;
350 	} else
351 	        pmp->pm_flags |= MSDOSFS_FATMIRROR;
352 
353 	/*
354 	 * More sanity checks:
355 	 *	MSDOSFS sectors per cluster: >0 && power of 2
356 	 *	MSDOSFS sector size: >= DEV_BSIZE && power of 2
357 	 *	HUGE sector count: >0
358 	 *	FAT sectors: >0
359 	 */
360 	if ((SecPerClust == 0) || (SecPerClust & (SecPerClust - 1)) ||
361 	    (pmp->pm_BytesPerSec < DEV_BSIZE) ||
362 	    (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1)) ||
363 	    (pmp->pm_HugeSectors == 0) || (pmp->pm_FATsecs == 0) ||
364 	    (SecPerClust * pmp->pm_BlkPerSec > MAXBSIZE / DEV_BSIZE)) {
365 		error = EINVAL;
366 		goto error_exit;
367 	}
368 
369 	pmp->pm_HugeSectors *= pmp->pm_BlkPerSec;
370 	pmp->pm_HiddenSects *= pmp->pm_BlkPerSec;
371 	pmp->pm_FATsecs *= pmp->pm_BlkPerSec;
372 	pmp->pm_fatblk = pmp->pm_ResSectors * pmp->pm_BlkPerSec;
373 	SecPerClust *= pmp->pm_BlkPerSec;
374 
375 	if (FAT32(pmp)) {
376 	        pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
377 		pmp->pm_firstcluster = pmp->pm_fatblk
378 		        + (pmp->pm_FATs * pmp->pm_FATsecs);
379 		pmp->pm_fsinfo = getushort(b710->bpbFSInfo) * pmp->pm_BlkPerSec;
380 	} else {
381 	        pmp->pm_rootdirblk = pmp->pm_fatblk +
382 		        (pmp->pm_FATs * pmp->pm_FATsecs);
383 		pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
384 				       + DEV_BSIZE - 1) / DEV_BSIZE;
385 		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
386 	}
387 
388 	pmp->pm_nmbrofclusters = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
389 	    SecPerClust;
390 	pmp->pm_maxcluster = pmp->pm_nmbrofclusters + 1;
391 	pmp->pm_fatsize = pmp->pm_FATsecs * DEV_BSIZE;
392 
393 	if (pmp->pm_fatmask == 0) {
394 		if (pmp->pm_maxcluster
395 		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
396 			/*
397 			 * This will usually be a floppy disk. This size makes
398 			 * sure that one fat entry will not be split across
399 			 * multiple blocks.
400 			 */
401 			pmp->pm_fatmask = FAT12_MASK;
402 			pmp->pm_fatmult = 3;
403 			pmp->pm_fatdiv = 2;
404 		} else {
405 			pmp->pm_fatmask = FAT16_MASK;
406 			pmp->pm_fatmult = 2;
407 			pmp->pm_fatdiv = 1;
408 		}
409 	}
410 	if (FAT12(pmp))
411 		pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
412 	else
413 		pmp->pm_fatblocksize = MAXBSIZE;
414 
415 	/*
416 	 * We now have the number of sectors in each FAT, so can work
417 	 * out how many clusters can be represented in a FAT.  Let's
418 	 * make sure the file system doesn't claim to have more clusters
419 	 * than this.
420 	 *
421 	 * We perform the calculation like we do to avoid integer overflow.
422 	 *
423 	 * This will give us a count of clusters.  They are numbered
424 	 * from 0, so the max cluster value is one less than the value
425 	 * we end up with.
426 	 */
427 	fat_max_clusters = pmp->pm_fatsize / pmp->pm_fatmult;
428 	fat_max_clusters *= pmp->pm_fatdiv;
429 	if (pmp->pm_maxcluster >= fat_max_clusters) {
430 #ifndef SMALL_KERNEL
431 		printf("msdosfs: reducing max cluster to %d from %d "
432 		    "due to FAT size\n", fat_max_clusters - 1,
433 		    pmp->pm_maxcluster);
434 #endif
435 		pmp->pm_maxcluster = fat_max_clusters - 1;
436 	}
437 
438 	pmp->pm_fatblocksec = pmp->pm_fatblocksize / DEV_BSIZE;
439 	pmp->pm_bnshift = ffs(DEV_BSIZE) - 1;
440 
441 	/*
442 	 * Compute mask and shift value for isolating cluster relative byte
443 	 * offsets and cluster numbers from a file offset.
444 	 */
445 	pmp->pm_bpcluster = SecPerClust * DEV_BSIZE;
446 	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
447 	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;
448 
449 	/*
450 	 * Check for valid cluster size
451 	 * must be a power of 2
452 	 */
453 	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
454 		error = EINVAL;
455 		goto error_exit;
456 	}
457 
458 	/*
459 	 * Release the bootsector buffer.
460 	 */
461 	brelse(bp);
462 	bp = NULL;
463 
464 	/*
465 	 * Check FSInfo
466 	 */
467 	if (pmp->pm_fsinfo) {
468 	        struct fsinfo *fp;
469 
470 		if ((error = bread(devvp, pmp->pm_fsinfo, fsi_size(pmp),
471 		    &bp)) != 0)
472 		        goto error_exit;
473 		fp = (struct fsinfo *)bp->b_data;
474 		if (!bcmp(fp->fsisig1, "RRaA", 4)
475 		    && !bcmp(fp->fsisig2, "rrAa", 4)
476 		    && !bcmp(fp->fsisig3, "\0\0\125\252", 4)
477 		    && !bcmp(fp->fsisig4, "\0\0\125\252", 4))
478 		        /* Valid FSInfo. */
479 			;
480 		else
481 		        pmp->pm_fsinfo = 0;
482 		/* XXX make sure this tiny buf doesn't come back in fillinusemap! */
483 		SET(bp->b_flags, B_INVAL);
484 		brelse(bp);
485 		bp = NULL;
486 	}
487 
488 	/*
489 	 * Check and validate (or perhaps invalidate?) the fsinfo structure? XXX
490 	 */
491 
492 	/*
493 	 * Allocate memory for the bitmap of allocated clusters, and then
494 	 * fill it in.
495 	 */
496 	bmapsiz = howmany(pmp->pm_maxcluster + 1, N_INUSEBITS);
497 	if (bmapsiz == 0 || SIZE_MAX / bmapsiz < sizeof(*pmp->pm_inusemap)) {
498 		/* detect multiplicative integer overflow */
499 		error = EINVAL;
500 		goto error_exit;
501 	}
502 	pmp->pm_inusemap = mallocarray(bmapsiz, sizeof(*pmp->pm_inusemap),
503 	    M_MSDOSFSFAT, M_WAITOK | M_CANFAIL);
504 	if (pmp->pm_inusemap == NULL) {
505 		error = EINVAL;
506 		goto error_exit;
507 	}
508 
509 	/*
510 	 * fillinusemap() needs pm_devvp.
511 	 */
512 	pmp->pm_dev = dev;
513 	pmp->pm_devvp = devvp;
514 
515 	/*
516 	 * Have the inuse map filled in.
517 	 */
518 	if ((error = fillinusemap(pmp)) != 0)
519 		goto error_exit;
520 
521 	/*
522 	 * If they want fat updates to be synchronous then let them suffer
523 	 * the performance degradation in exchange for the on disk copy of
524 	 * the fat being correct just about all the time.  I suppose this
525 	 * would be a good thing to turn on if the kernel is still flakey.
526 	 */
527 	if (mp->mnt_flag & MNT_SYNCHRONOUS)
528 		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;
529 
530 	/*
531 	 * Finish up.
532 	 */
533 	if (ronly)
534 		pmp->pm_flags |= MSDOSFSMNT_RONLY;
535 	else
536 		pmp->pm_fmod = 1;
537 	mp->mnt_data = pmp;
538         mp->mnt_stat.f_fsid.val[0] = (long)dev;
539         mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
540 #ifdef QUOTA
541 	/*
542 	 * If we ever do quotas for DOS filesystems this would be a place
543 	 * to fill in the info in the msdosfsmount structure. You dolt,
544 	 * quotas on dos filesystems make no sense because files have no
545 	 * owners on dos filesystems. of course there is some empty space
546 	 * in the directory entry where we could put uid's and gid's.
547 	 */
548 #endif
549 	devvp->v_specmountpoint = mp;
550 
551 	return (0);
552 
553 error_exit:
554 	if (devvp->v_specinfo)
555 		devvp->v_specmountpoint = NULL;
556 	if (bp)
557 		brelse(bp);
558 
559 	vn_lock(devvp, LK_EXCLUSIVE|LK_RETRY);
560 	(void) VOP_CLOSE(devvp, ronly ? FREAD : FREAD|FWRITE, NOCRED, p);
561 	VOP_UNLOCK(devvp);
562 
563 	if (pmp) {
564 		if (pmp->pm_inusemap)
565 			free(pmp->pm_inusemap, M_MSDOSFSFAT, 0);
566 		free(pmp, M_MSDOSFSMNT, 0);
567 		mp->mnt_data = NULL;
568 	}
569 	return (error);
570 }
571 
572 int
573 msdosfs_start(struct mount *mp, int flags, struct proc *p)
574 {
575 
576 	return (0);
577 }
578 
579 /*
580  * Unmount the filesystem described by mp.
581  */
582 int
583 msdosfs_unmount(struct mount *mp, int mntflags,struct proc *p)
584 {
585 	struct msdosfsmount *pmp;
586 	int error, flags;
587 	struct vnode *vp;
588 
589 	flags = 0;
590 	if (mntflags & MNT_FORCE)
591 		flags |= FORCECLOSE;
592 	if ((error = vflush(mp, NULLVP, flags)) != 0)
593 		return (error);
594 	pmp = VFSTOMSDOSFS(mp);
595 	pmp->pm_devvp->v_specmountpoint = NULL;
596 	vp = pmp->pm_devvp;
597 #ifdef MSDOSFS_DEBUG
598 	vprint("msdosfs_umount(): just before calling VOP_CLOSE()\n", vp);
599 #endif
600 	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
601 	(void)VOP_CLOSE(vp,
602 	    pmp->pm_flags & MSDOSFSMNT_RONLY ? FREAD : FREAD|FWRITE, NOCRED, p);
603 	vput(vp);
604 	free(pmp->pm_inusemap, M_MSDOSFSFAT, 0);
605 	free(pmp, M_MSDOSFSMNT, 0);
606 	mp->mnt_data = NULL;
607 	mp->mnt_flag &= ~MNT_LOCAL;
608 	return (0);
609 }
610 
611 int
612 msdosfs_root(struct mount *mp, struct vnode **vpp)
613 {
614 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
615 	struct denode *ndep;
616 	int error;
617 
618 	if ((error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, &ndep)) != 0)
619 		return (error);
620 
621 #ifdef MSDOSFS_DEBUG
622 	printf("msdosfs_root(); mp %p, pmp %p, ndep %p, vp %p\n",
623 	    mp, pmp, ndep, DETOV(ndep));
624 #endif
625 
626 	*vpp = DETOV(ndep);
627 	return (0);
628 }
629 
630 int
631 msdosfs_statfs(struct mount *mp, struct statfs *sbp, struct proc *p)
632 {
633 	struct msdosfsmount *pmp;
634 
635 	pmp = VFSTOMSDOSFS(mp);
636 	sbp->f_bsize = pmp->pm_bpcluster;
637 	sbp->f_iosize = pmp->pm_bpcluster;
638 	sbp->f_blocks = pmp->pm_nmbrofclusters;
639 	sbp->f_bfree = pmp->pm_freeclustercount;
640 	sbp->f_bavail = pmp->pm_freeclustercount;
641 	sbp->f_files = pmp->pm_RootDirEnts;			/* XXX */
642 	sbp->f_ffree = sbp->f_favail = 0;	/* what to put in here? */
643 	copy_statfs_info(sbp, mp);
644 
645 	return (0);
646 }
647 
648 
649 struct msdosfs_sync_arg {
650 	struct proc *p;
651 	struct ucred *cred;
652 	int allerror;
653 	int waitfor;
654 };
655 
656 int
657 msdosfs_sync_vnode(struct vnode *vp, void *arg)
658 {
659 	struct msdosfs_sync_arg *msa = arg;
660 	int error;
661 	struct denode *dep;
662 
663 	dep = VTODE(vp);
664 	if (vp->v_type == VNON ||
665 	    ((dep->de_flag & (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0
666 	      && LIST_EMPTY(&vp->v_dirtyblkhd)) ||
667 	    msa->waitfor == MNT_LAZY) {
668 		return (0);
669 	}
670 
671 	if (vget(vp, LK_EXCLUSIVE | LK_NOWAIT))
672 		return (0);
673 
674 	if ((error = VOP_FSYNC(vp, msa->cred, msa->waitfor, msa->p)) != 0)
675 		msa->allerror = error;
676 	VOP_UNLOCK(vp);
677 	vrele(vp);
678 
679 	return (0);
680 }
681 
682 
683 int
684 msdosfs_sync(struct mount *mp, int waitfor, int stall, struct ucred *cred,
685     struct proc *p)
686 {
687 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
688 	struct msdosfs_sync_arg msa;
689 	int error;
690 
691 	msa.allerror = 0;
692 	msa.p = p;
693 	msa.cred = cred;
694 	msa.waitfor = waitfor;
695 
696 	/*
697 	 * If we ever switch to not updating all of the fats all the time,
698 	 * this would be the place to update them from the first one.
699 	 */
700 	if (pmp->pm_fmod != 0) {
701 		if (pmp->pm_flags & MSDOSFSMNT_RONLY)
702 			panic("msdosfs_sync: rofs mod");
703 		else {
704 			/* update fats here */
705 		}
706 	}
707 	/*
708 	 * Write back each (modified) denode.
709 	 */
710 	vfs_mount_foreach_vnode(mp, msdosfs_sync_vnode, &msa);
711 
712 	/*
713 	 * Force stale file system control information to be flushed.
714 	 */
715 	if (waitfor != MNT_LAZY) {
716 		vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY);
717 		if ((error = VOP_FSYNC(pmp->pm_devvp, cred, waitfor, p)) != 0)
718 			msa.allerror = error;
719 		VOP_UNLOCK(pmp->pm_devvp);
720 	}
721 
722 	return (msa.allerror);
723 }
724 
725 int
726 msdosfs_fhtovp(struct mount *mp, struct fid *fhp, struct vnode **vpp)
727 {
728 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
729 	struct defid *defhp = (struct defid *) fhp;
730 	struct denode *dep;
731 	int error;
732 
733 	error = deget(pmp, defhp->defid_dirclust, defhp->defid_dirofs, &dep);
734 	if (error) {
735 		*vpp = NULLVP;
736 		return (error);
737 	}
738 	*vpp = DETOV(dep);
739 	return (0);
740 }
741 
742 int
743 msdosfs_vptofh(struct vnode *vp, struct fid *fhp)
744 {
745 	struct denode *dep;
746 	struct defid *defhp;
747 
748 	dep = VTODE(vp);
749 	defhp = (struct defid *)fhp;
750 	defhp->defid_len = sizeof(struct defid);
751 	defhp->defid_dirclust = dep->de_dirclust;
752 	defhp->defid_dirofs = dep->de_diroffset;
753 	/* defhp->defid_gen = dep->de_gen; */
754 	return (0);
755 }
756 
757 int
758 msdosfs_check_export(struct mount *mp, struct mbuf *nam, int *exflagsp,
759     struct ucred **credanonp)
760 {
761 	struct netcred *np;
762 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
763 
764 	/*
765 	 * Get the export permission structure for this <mp, client> tuple.
766 	 */
767 	np = vfs_export_lookup(mp, &pmp->pm_export, nam);
768 	if (np == NULL)
769 		return (EACCES);
770 
771 	*exflagsp = np->netc_exflags;
772 	*credanonp = &np->netc_anon;
773 	return (0);
774 }
775 
776 #define msdosfs_vget ((int (*)(struct mount *, ino_t, struct vnode **)) \
777 		      eopnotsupp)
778 
779 #define msdosfs_quotactl ((int (*)(struct mount *, int, uid_t, caddr_t, \
780 					struct proc *))eopnotsupp)
781 
782 #define msdosfs_sysctl ((int (*)(int *, u_int, void *, size_t *, void *, \
783                                     size_t, struct proc *))eopnotsupp)
784 
785 const struct vfsops msdosfs_vfsops = {
786 	.vfs_mount	= msdosfs_mount,
787 	.vfs_start	= msdosfs_start,
788 	.vfs_unmount	= msdosfs_unmount,
789 	.vfs_root	= msdosfs_root,
790 	.vfs_quotactl	= msdosfs_quotactl,
791 	.vfs_statfs	= msdosfs_statfs,
792 	.vfs_sync	= msdosfs_sync,
793 	.vfs_vget	= msdosfs_vget,
794 	.vfs_fhtovp	= msdosfs_fhtovp,
795 	.vfs_vptofh	= msdosfs_vptofh,
796 	.vfs_init	= msdosfs_init,
797 	.vfs_sysctl	= msdosfs_sysctl,
798 	.vfs_checkexp	= msdosfs_check_export,
799 };
800