xref: /freebsd/sys/fs/msdosfs/msdosfs_vfsops.c (revision daf1cffce2e07931f27c6c6998652e90df6ba87e)
1 /* $FreeBSD$ */
2 /*	$NetBSD: msdosfs_vfsops.c,v 1.51 1997/11/17 15:36:58 ws 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/conf.h>
54 #include <sys/namei.h>
55 #include <sys/proc.h>
56 #include <sys/kernel.h>
57 #include <sys/vnode.h>
58 #include <sys/mount.h>
59 #include <sys/buf.h>
60 #include <sys/fcntl.h>
61 #include <sys/malloc.h>
62 #include <sys/stat.h> 				/* defines ALLPERMS */
63 #include <vm/vm_zone.h>
64 
65 #include <msdosfs/bpb.h>
66 #include <msdosfs/bootsect.h>
67 #include <msdosfs/direntry.h>
68 #include <msdosfs/denode.h>
69 #include <msdosfs/msdosfsmount.h>
70 #include <msdosfs/fat.h>
71 
72 #if 1 /*def PC98*/
73 /*
74  * XXX - The boot signature formatted by NEC PC-98 DOS looks like a
75  *       garbage or a random value :-{
76  *       If you want to use that broken-signatured media, define the
77  *       following symbol even though PC/AT.
78  *       (ex. mount PC-98 DOS formatted FD on PC/AT)
79  */
80 #define	MSDOSFS_NOCHECKSIG
81 #endif
82 
83 MALLOC_DEFINE(M_MSDOSFSMNT, "MSDOSFS mount", "MSDOSFS mount structure");
84 static MALLOC_DEFINE(M_MSDOSFSFAT, "MSDOSFS FAT", "MSDOSFS file allocation table");
85 
86 static int	update_mp __P((struct mount *mp, struct msdosfs_args *argp));
87 static int	mountmsdosfs __P((struct vnode *devvp, struct mount *mp,
88 				  struct proc *p, struct msdosfs_args *argp));
89 static int	msdosfs_fhtovp __P((struct mount *, struct fid *,
90 				    struct vnode **));
91 static int	msdosfs_checkexp __P((struct mount *, struct sockaddr *,
92 				    int *, struct ucred **));
93 static int	msdosfs_mount __P((struct mount *, char *, caddr_t,
94 				   struct nameidata *, struct proc *));
95 static int	msdosfs_root __P((struct mount *, struct vnode **));
96 static int	msdosfs_statfs __P((struct mount *, struct statfs *,
97 				    struct proc *));
98 static int	msdosfs_sync __P((struct mount *, int, struct ucred *,
99 				  struct proc *));
100 static int	msdosfs_unmount __P((struct mount *, int, struct proc *));
101 static int	msdosfs_vptofh __P((struct vnode *, struct fid *));
102 
103 static int
104 update_mp(mp, argp)
105 	struct mount *mp;
106 	struct msdosfs_args *argp;
107 {
108 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
109 	int error;
110 
111 	pmp->pm_gid = argp->gid;
112 	pmp->pm_uid = argp->uid;
113 	pmp->pm_mask = argp->mask & ALLPERMS;
114 	pmp->pm_flags |= argp->flags & MSDOSFSMNT_MNTOPT;
115 	if (pmp->pm_flags & MSDOSFSMNT_U2WTABLE) {
116 		bcopy(argp->u2w, pmp->pm_u2w, sizeof(pmp->pm_u2w));
117 		bcopy(argp->d2u, pmp->pm_d2u, sizeof(pmp->pm_d2u));
118 		bcopy(argp->u2d, pmp->pm_u2d, sizeof(pmp->pm_u2d));
119 	}
120 	if (pmp->pm_flags & MSDOSFSMNT_ULTABLE) {
121 		bcopy(argp->ul, pmp->pm_ul, sizeof(pmp->pm_ul));
122 		bcopy(argp->lu, pmp->pm_lu, sizeof(pmp->pm_lu));
123 	}
124 
125 #ifndef __FreeBSD__
126 	/*
127 	 * GEMDOS knows nothing (yet) about win95
128 	 */
129 	if (pmp->pm_flags & MSDOSFSMNT_GEMDOSFS)
130 		pmp->pm_flags |= MSDOSFSMNT_NOWIN95;
131 #endif
132 
133 	if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
134 		pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
135 	else if (!(pmp->pm_flags &
136 	    (MSDOSFSMNT_SHORTNAME | MSDOSFSMNT_LONGNAME))) {
137 		struct vnode *rootvp;
138 
139 		/*
140 		 * Try to divine whether to support Win'95 long filenames
141 		 */
142 		if (FAT32(pmp))
143 			pmp->pm_flags |= MSDOSFSMNT_LONGNAME;
144 		else {
145 			if ((error = msdosfs_root(mp, &rootvp)) != 0)
146 				return error;
147 			pmp->pm_flags |= findwin95(VTODE(rootvp))
148 				? MSDOSFSMNT_LONGNAME
149 					: MSDOSFSMNT_SHORTNAME;
150 			vput(rootvp);
151 		}
152 	}
153 	return 0;
154 }
155 
156 #ifndef __FreeBSD__
157 int
158 msdosfs_mountroot()
159 {
160 	register struct mount *mp;
161 	struct proc *p = curproc;	/* XXX */
162 	size_t size;
163 	int error;
164 	struct msdosfs_args args;
165 
166 	if (root_device->dv_class != DV_DISK)
167 		return (ENODEV);
168 
169 	/*
170 	 * Get vnodes for swapdev and rootdev.
171 	 */
172 	if (bdevvp(rootdev, &rootvp))
173 		panic("msdosfs_mountroot: can't setup rootvp");
174 
175 	mp = malloc((u_long)sizeof(struct mount), M_MOUNT, M_WAITOK);
176 	bzero((char *)mp, (u_long)sizeof(struct mount));
177 	mp->mnt_op = &msdosfs_vfsops;
178 	mp->mnt_flag = 0;
179 	LIST_INIT(&mp->mnt_vnodelist);
180 
181 	args.flags = 0;
182 	args.uid = 0;
183 	args.gid = 0;
184 	args.mask = 0777;
185 
186 	if ((error = mountmsdosfs(rootvp, mp, p, &args)) != 0) {
187 		free(mp, M_MOUNT);
188 		return (error);
189 	}
190 
191 	if ((error = update_mp(mp, &args)) != 0) {
192 		(void)msdosfs_unmount(mp, 0, p);
193 		free(mp, M_MOUNT);
194 		return (error);
195 	}
196 
197 	if ((error = vfs_lock(mp)) != 0) {
198 		(void)msdosfs_unmount(mp, 0, p);
199 		free(mp, M_MOUNT);
200 		return (error);
201 	}
202 
203 	TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
204 	mp->mnt_vnodecovered = NULLVP;
205 	(void) copystr("/", mp->mnt_stat.f_mntonname, MNAMELEN - 1,
206 	    &size);
207 	bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size);
208 	(void) copystr(ROOTNAME, mp->mnt_stat.f_mntfromname, MNAMELEN - 1,
209 	    &size);
210 	bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
211 	(void)msdosfs_statfs(mp, &mp->mnt_stat, p);
212 	vfs_unlock(mp);
213 	return (0);
214 }
215 #endif
216 
217 /*
218  * mp - path - addr in user space of mount point (ie /usr or whatever)
219  * data - addr in user space of mount params including the name of the block
220  * special file to treat as a filesystem.
221  */
222 static int
223 msdosfs_mount(mp, path, data, ndp, p)
224 	struct mount *mp;
225 	char *path;
226 	caddr_t data;
227 	struct nameidata *ndp;
228 	struct proc *p;
229 {
230 	struct vnode *devvp;	  /* vnode for blk device to mount */
231 	struct msdosfs_args args; /* will hold data from mount request */
232 	/* msdosfs specific mount control block */
233 	struct msdosfsmount *pmp = NULL;
234 	size_t size;
235 	int error, flags;
236 	mode_t accessmode;
237 
238 	error = copyin(data, (caddr_t)&args, sizeof(struct msdosfs_args));
239 	if (error)
240 		return (error);
241 	if (args.magic != MSDOSFS_ARGSMAGIC)
242 		args.flags = 0;
243 	/*
244 	 * If updating, check whether changing from read-only to
245 	 * read/write; if there is no device name, that's all we do.
246 	 */
247 	if (mp->mnt_flag & MNT_UPDATE) {
248 		pmp = VFSTOMSDOSFS(mp);
249 		error = 0;
250 		if (!(pmp->pm_flags & MSDOSFSMNT_RONLY) && (mp->mnt_flag & MNT_RDONLY)) {
251 			flags = WRITECLOSE;
252 			if (mp->mnt_flag & MNT_FORCE)
253 				flags |= FORCECLOSE;
254 			error = vflush(mp, NULLVP, flags);
255 		}
256 		if (!error && (mp->mnt_flag & MNT_RELOAD))
257 			/* not yet implemented */
258 			error = EOPNOTSUPP;
259 		if (error)
260 			return (error);
261 		if ((pmp->pm_flags & MSDOSFSMNT_RONLY) && (mp->mnt_kern_flag & MNTK_WANTRDWR)) {
262 			/*
263 			 * If upgrade to read-write by non-root, then verify
264 			 * that user has necessary permissions on the device.
265 			 */
266 			if (p->p_ucred->cr_uid != 0) {
267 				devvp = pmp->pm_devvp;
268 				vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY, p);
269 				error = VOP_ACCESS(devvp, VREAD | VWRITE,
270 						   p->p_ucred, p);
271 				if (error) {
272 					VOP_UNLOCK(devvp, 0, p);
273 					return (error);
274 				}
275 				VOP_UNLOCK(devvp, 0, p);
276 			}
277 			pmp->pm_flags &= ~MSDOSFSMNT_RONLY;
278 		}
279 		if (args.fspec == 0) {
280 #ifdef	__notyet__		/* doesn't work correctly with current mountd	XXX */
281 			if (args.flags & MSDOSFSMNT_MNTOPT) {
282 				pmp->pm_flags &= ~MSDOSFSMNT_MNTOPT;
283 				pmp->pm_flags |= args.flags & MSDOSFSMNT_MNTOPT;
284 				if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
285 					pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
286 			}
287 #endif
288 			/*
289 			 * Process export requests.
290 			 */
291 			return (vfs_export(mp, &pmp->pm_export, &args.export));
292 		}
293 	}
294 	/*
295 	 * Not an update, or updating the name: look up the name
296 	 * and verify that it refers to a sensible block device.
297 	 */
298 	NDINIT(ndp, LOOKUP, FOLLOW, UIO_USERSPACE, args.fspec, p);
299 	error = namei(ndp);
300 	if (error)
301 		return (error);
302 	devvp = ndp->ni_vp;
303 	NDFREE(ndp, NDF_ONLY_PNBUF);
304 
305 	if (!vn_isdisk(devvp, &error)) {
306 		vrele(devvp);
307 		return (error);
308 	}
309 	/*
310 	 * If mount by non-root, then verify that user has necessary
311 	 * permissions on the device.
312 	 */
313 	if (p->p_ucred->cr_uid != 0) {
314 		accessmode = VREAD;
315 		if ((mp->mnt_flag & MNT_RDONLY) == 0)
316 			accessmode |= VWRITE;
317 		vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY, p);
318 		error = VOP_ACCESS(devvp, accessmode, p->p_ucred, p);
319 		if (error) {
320 			vput(devvp);
321 			return (error);
322 		}
323 		VOP_UNLOCK(devvp, 0, p);
324 	}
325 	if ((mp->mnt_flag & MNT_UPDATE) == 0) {
326 		error = mountmsdosfs(devvp, mp, p, &args);
327 #ifdef MSDOSFS_DEBUG		/* only needed for the printf below */
328 		pmp = VFSTOMSDOSFS(mp);
329 #endif
330 	} else {
331 		if (devvp != pmp->pm_devvp)
332 			error = EINVAL;	/* XXX needs translation */
333 		else
334 			vrele(devvp);
335 	}
336 	if (error) {
337 		vrele(devvp);
338 		return (error);
339 	}
340 
341 	error = update_mp(mp, &args);
342 	if (error) {
343 		msdosfs_unmount(mp, MNT_FORCE, p);
344 		return error;
345 	}
346 
347 	(void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size);
348 	bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size);
349 	(void) copyinstr(args.fspec, mp->mnt_stat.f_mntfromname, MNAMELEN - 1,
350 	    &size);
351 	bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
352 	(void) msdosfs_statfs(mp, &mp->mnt_stat, p);
353 #ifdef MSDOSFS_DEBUG
354 	printf("msdosfs_mount(): mp %p, pmp %p, inusemap %p\n", mp, pmp, pmp->pm_inusemap);
355 #endif
356 	return (0);
357 }
358 
359 static int
360 mountmsdosfs(devvp, mp, p, argp)
361 	struct vnode *devvp;
362 	struct mount *mp;
363 	struct proc *p;
364 	struct msdosfs_args *argp;
365 {
366 	struct msdosfsmount *pmp;
367 	struct buf *bp;
368 	dev_t dev = devvp->v_rdev;
369 #ifndef __FreeBSD__
370 	struct partinfo dpart;
371 	int bsize = 0, dtype = 0, tmp;
372 #endif
373 	union bootsector *bsp;
374 	struct byte_bpb33 *b33;
375 	struct byte_bpb50 *b50;
376 	struct byte_bpb710 *b710;
377 	u_int8_t SecPerClust;
378 	u_long clusters;
379 	int	ronly, error;
380 
381 	/*
382 	 * Disallow multiple mounts of the same device.
383 	 * Disallow mounting of a device that is currently in use
384 	 * (except for root, which might share swap device for miniroot).
385 	 * Flush out any old buffers remaining from a previous use.
386 	 */
387 	error = vfs_mountedon(devvp);
388 	if (error)
389 		return (error);
390 	if (vcount(devvp) > 1 && devvp != rootvp)
391 		return (EBUSY);
392 	vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY, p);
393 	error = vinvalbuf(devvp, V_SAVE, p->p_ucred, p, 0, 0);
394 	VOP_UNLOCK(devvp, 0, p);
395 	if (error)
396 		return (error);
397 
398 	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
399 	vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY, p);
400 	error = VOP_OPEN(devvp, ronly ? FREAD : FREAD|FWRITE, FSCRED, p);
401 	VOP_UNLOCK(devvp, 0, p);
402 	if (error)
403 		return (error);
404 
405 	bp  = NULL; /* both used in error_exit */
406 	pmp = NULL;
407 
408 #ifndef __FreeBSD__
409 	if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
410 		/*
411 	 	 * We need the disklabel to calculate the size of a FAT entry
412 		 * later on. Also make sure the partition contains a filesystem
413 		 * of type FS_MSDOS. This doesn't work for floppies, so we have
414 		 * to check for them too.
415 	 	 *
416 	 	 * At least some parts of the msdos fs driver seem to assume
417 		 * that the size of a disk block will always be 512 bytes.
418 		 * Let's check it...
419 		 */
420 		error = VOP_IOCTL(devvp, DIOCGPART, (caddr_t)&dpart,
421 				  FREAD, NOCRED, p);
422 		if (error)
423 			goto error_exit;
424 		tmp   = dpart.part->p_fstype;
425 		dtype = dpart.disklab->d_type;
426 		bsize = dpart.disklab->d_secsize;
427 		if (bsize != 512 || (dtype!=DTYPE_FLOPPY && tmp!=FS_MSDOS)) {
428 			error = EINVAL;
429 			goto error_exit;
430 		}
431 	}
432 #endif
433 
434 	/*
435 	 * Read the boot sector of the filesystem, and then check the
436 	 * boot signature.  If not a dos boot sector then error out.
437 	 *
438 	 * NOTE: 2048 is a maximum sector size in current...
439 	 */
440 	error = bread(devvp, 0, 2048, NOCRED, &bp);
441 	if (error)
442 		goto error_exit;
443 	bp->b_flags |= B_AGE;
444 	bsp = (union bootsector *)bp->b_data;
445 	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
446 	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
447 	b710 = (struct byte_bpb710 *)bsp->bs710.bsPBP;
448 
449 #ifndef __FreeBSD__
450 	if (!(argp->flags & MSDOSFSMNT_GEMDOSFS)) {
451 #endif
452 #ifndef MSDOSFS_NOCHECKSIG
453 		if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
454 		    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
455 			error = EINVAL;
456 			goto error_exit;
457 		}
458 #endif
459 #ifndef __FreeBSD__
460 	}
461 #endif
462 
463 	pmp = malloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK);
464 	bzero((caddr_t)pmp, sizeof *pmp);
465 	pmp->pm_mountp = mp;
466 
467 	/*
468 	 * Compute several useful quantities from the bpb in the
469 	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
470 	 * the fields that are different between dos 5 and dos 3.3.
471 	 */
472 	SecPerClust = b50->bpbSecPerClust;
473 	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
474 	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
475 	pmp->pm_FATs = b50->bpbFATs;
476 	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
477 	pmp->pm_Sectors = getushort(b50->bpbSectors);
478 	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
479 	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
480 	pmp->pm_Heads = getushort(b50->bpbHeads);
481 	pmp->pm_Media = b50->bpbMedia;
482 
483 	/* calculate the ratio of sector size to DEV_BSIZE */
484 	pmp->pm_BlkPerSec = pmp->pm_BytesPerSec / DEV_BSIZE;
485 
486 #ifndef __FreeBSD__
487 	if (!(argp->flags & MSDOSFSMNT_GEMDOSFS)) {
488 #endif
489 		/* XXX - We should probably check more values here */
490 		if (!pmp->pm_BytesPerSec || !SecPerClust
491 			|| !pmp->pm_Heads || pmp->pm_Heads > 255
492 #ifdef PC98
493 	    		|| !pmp->pm_SecPerTrack || pmp->pm_SecPerTrack > 255) {
494 #else
495 			|| !pmp->pm_SecPerTrack || pmp->pm_SecPerTrack > 63) {
496 #endif
497 			error = EINVAL;
498 			goto error_exit;
499 		}
500 #ifndef __FreeBSD__
501 	}
502 #endif
503 
504 	if (pmp->pm_Sectors == 0) {
505 		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
506 		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
507 	} else {
508 		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
509 		pmp->pm_HugeSectors = pmp->pm_Sectors;
510 	}
511 	if (pmp->pm_HugeSectors > 0xffffffff /
512 	    (pmp->pm_BytesPerSec / sizeof(struct direntry)) + 1) {
513 		/*
514 		 * We cannot deal currently with this size of disk
515 		 * due to fileid limitations (see msdosfs_getattr and
516 		 * msdosfs_readdir)
517 		 */
518 		error = EINVAL;
519 		printf("mountmsdosfs(): disk too big, sorry\n");
520 		goto error_exit;
521 	}
522 
523 	if (pmp->pm_RootDirEnts == 0) {
524 		if (bsp->bs710.bsBootSectSig2 != BOOTSIG2
525 		    || bsp->bs710.bsBootSectSig3 != BOOTSIG3
526 		    || pmp->pm_Sectors
527 		    || pmp->pm_FATsecs
528 		    || getushort(b710->bpbFSVers)) {
529 			error = EINVAL;
530 			printf("mountmsdosfs(): bad FAT32 filesystem\n");
531 			goto error_exit;
532 		}
533 		pmp->pm_fatmask = FAT32_MASK;
534 		pmp->pm_fatmult = 4;
535 		pmp->pm_fatdiv = 1;
536 		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);
537 		if (getushort(b710->bpbExtFlags) & FATMIRROR)
538 			pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
539 		else
540 			pmp->pm_flags |= MSDOSFS_FATMIRROR;
541 	} else
542 		pmp->pm_flags |= MSDOSFS_FATMIRROR;
543 
544 	/*
545 	 * Check a few values (could do some more):
546 	 * - logical sector size: power of 2, >= block size
547 	 * - sectors per cluster: power of 2, >= 1
548 	 * - number of sectors:   >= 1, <= size of partition
549 	 */
550 	if ( (SecPerClust == 0)
551 	  || (SecPerClust & (SecPerClust - 1))
552 	  || (pmp->pm_BytesPerSec < DEV_BSIZE)
553 	  || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
554 	  || (pmp->pm_HugeSectors == 0)
555 	) {
556 		error = EINVAL;
557 		goto error_exit;
558 	}
559 
560 	pmp->pm_HugeSectors *= pmp->pm_BlkPerSec;
561 	pmp->pm_HiddenSects *= pmp->pm_BlkPerSec; /* XXX not used? */
562 	pmp->pm_FATsecs     *= pmp->pm_BlkPerSec;
563 	SecPerClust         *= pmp->pm_BlkPerSec;
564 
565 	pmp->pm_fatblk = pmp->pm_ResSectors * pmp->pm_BlkPerSec;
566 
567 	if (FAT32(pmp)) {
568 		pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
569 		pmp->pm_firstcluster = pmp->pm_fatblk
570 			+ (pmp->pm_FATs * pmp->pm_FATsecs);
571 		pmp->pm_fsinfo = getushort(b710->bpbFSInfo) * pmp->pm_BlkPerSec;
572 	} else {
573 		pmp->pm_rootdirblk = pmp->pm_fatblk +
574 			(pmp->pm_FATs * pmp->pm_FATsecs);
575 		pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
576 				       + DEV_BSIZE - 1)
577 			/ DEV_BSIZE; /* in blocks */
578 		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
579 	}
580 
581 	pmp->pm_maxcluster = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
582 	    SecPerClust + 1;
583 	pmp->pm_fatsize = pmp->pm_FATsecs * DEV_BSIZE; /* XXX not used? */
584 
585 #ifndef __FreeBSD__
586 	if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
587 		if ((pmp->pm_maxcluster <= (0xff0 - 2))
588 		      && ((dtype == DTYPE_FLOPPY) || ((dtype == DTYPE_VNODE)
589 		      && ((pmp->pm_Heads == 1) || (pmp->pm_Heads == 2))))
590 		    ) {
591 			pmp->pm_fatmask = FAT12_MASK;
592 			pmp->pm_fatmult = 3;
593 			pmp->pm_fatdiv = 2;
594 		} else {
595 			pmp->pm_fatmask = FAT16_MASK;
596 			pmp->pm_fatmult = 2;
597 			pmp->pm_fatdiv = 1;
598 		}
599 	} else
600 #endif
601 	if (pmp->pm_fatmask == 0) {
602 		if (pmp->pm_maxcluster
603 		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
604 			/*
605 			 * This will usually be a floppy disk. This size makes
606 			 * sure that one fat entry will not be split across
607 			 * multiple blocks.
608 			 */
609 			pmp->pm_fatmask = FAT12_MASK;
610 			pmp->pm_fatmult = 3;
611 			pmp->pm_fatdiv = 2;
612 		} else {
613 			pmp->pm_fatmask = FAT16_MASK;
614 			pmp->pm_fatmult = 2;
615 			pmp->pm_fatdiv = 1;
616 		}
617 	}
618 
619 	clusters = (pmp->pm_fatsize / pmp->pm_fatmult) * pmp->pm_fatdiv;
620 	if (pmp->pm_maxcluster >= clusters) {
621 		printf("Warning: number of clusters (%ld) exceeds FAT "
622 		    "capacity (%ld)\n", pmp->pm_maxcluster + 1, clusters);
623 		pmp->pm_maxcluster = clusters - 1;
624 	}
625 
626 
627 	if (FAT12(pmp))
628 		pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
629 	else
630 		pmp->pm_fatblocksize = DFLTBSIZE;
631 
632 	pmp->pm_fatblocksec = pmp->pm_fatblocksize / DEV_BSIZE;
633 	pmp->pm_bnshift = ffs(DEV_BSIZE) - 1;
634 
635 	/*
636 	 * Compute mask and shift value for isolating cluster relative byte
637 	 * offsets and cluster numbers from a file offset.
638 	 */
639 	pmp->pm_bpcluster = SecPerClust * DEV_BSIZE;
640 	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
641 	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;
642 
643 	/*
644 	 * Check for valid cluster size
645 	 * must be a power of 2
646 	 */
647 	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
648 		error = EINVAL;
649 		goto error_exit;
650 	}
651 
652 	/*
653 	 * Release the bootsector buffer.
654 	 */
655 	brelse(bp);
656 	bp = NULL;
657 
658 	/*
659 	 * Check FSInfo.
660 	 */
661 	if (pmp->pm_fsinfo) {
662 		struct fsinfo *fp;
663 
664 		if ((error = bread(devvp, pmp->pm_fsinfo, fsi_size(pmp),
665 		    NOCRED, &bp)) != 0)
666 			goto error_exit;
667 		fp = (struct fsinfo *)bp->b_data;
668 		if (!bcmp(fp->fsisig1, "RRaA", 4)
669 		    && !bcmp(fp->fsisig2, "rrAa", 4)
670 		    && !bcmp(fp->fsisig3, "\0\0\125\252", 4)
671 		    && !bcmp(fp->fsisig4, "\0\0\125\252", 4))
672 			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
673 		else
674 			pmp->pm_fsinfo = 0;
675 		brelse(bp);
676 		bp = NULL;
677 	}
678 
679 	/*
680 	 * Check and validate (or perhaps invalidate?) the fsinfo structure?		XXX
681 	 */
682 
683 	/*
684 	 * Allocate memory for the bitmap of allocated clusters, and then
685 	 * fill it in.
686 	 */
687 	pmp->pm_inusemap = malloc(((pmp->pm_maxcluster + N_INUSEBITS - 1)
688 				   / N_INUSEBITS)
689 				  * sizeof(*pmp->pm_inusemap),
690 				  M_MSDOSFSFAT, M_WAITOK);
691 
692 	/*
693 	 * fillinusemap() needs pm_devvp.
694 	 */
695 	pmp->pm_dev = dev;
696 	pmp->pm_devvp = devvp;
697 
698 	/*
699 	 * Have the inuse map filled in.
700 	 */
701 	if ((error = fillinusemap(pmp)) != 0)
702 		goto error_exit;
703 
704 	/*
705 	 * If they want fat updates to be synchronous then let them suffer
706 	 * the performance degradation in exchange for the on disk copy of
707 	 * the fat being correct just about all the time.  I suppose this
708 	 * would be a good thing to turn on if the kernel is still flakey.
709 	 */
710 	if (mp->mnt_flag & MNT_SYNCHRONOUS)
711 		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;
712 
713 	/*
714 	 * Finish up.
715 	 */
716 	if (ronly)
717 		pmp->pm_flags |= MSDOSFSMNT_RONLY;
718 	else
719 		pmp->pm_fmod = 1;
720 	mp->mnt_data = (qaddr_t) pmp;
721 	mp->mnt_stat.f_fsid.val[0] = dev2udev(dev);
722 	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
723 	mp->mnt_flag |= MNT_LOCAL;
724 	devvp->v_specmountpoint = mp;
725 
726 	return 0;
727 
728 error_exit:
729 	if (bp)
730 		brelse(bp);
731 	(void) VOP_CLOSE(devvp, ronly ? FREAD : FREAD | FWRITE, NOCRED, p);
732 	if (pmp) {
733 		if (pmp->pm_inusemap)
734 			free(pmp->pm_inusemap, M_MSDOSFSFAT);
735 		free(pmp, M_MSDOSFSMNT);
736 		mp->mnt_data = (qaddr_t)0;
737 	}
738 	return (error);
739 }
740 
741 /*
742  * Unmount the filesystem described by mp.
743  */
744 static int
745 msdosfs_unmount(mp, mntflags, p)
746 	struct mount *mp;
747 	int mntflags;
748 	struct proc *p;
749 {
750 	struct msdosfsmount *pmp;
751 	int error, flags;
752 
753 	flags = 0;
754 	if (mntflags & MNT_FORCE)
755 		flags |= FORCECLOSE;
756 	error = vflush(mp, NULLVP, flags);
757 	if (error)
758 		return error;
759 	pmp = VFSTOMSDOSFS(mp);
760 	pmp->pm_devvp->v_specmountpoint = NULL;
761 #ifdef MSDOSFS_DEBUG
762 	{
763 		struct vnode *vp = pmp->pm_devvp;
764 
765 		printf("msdosfs_umount(): just before calling VOP_CLOSE()\n");
766 		printf("flag %08lx, usecount %d, writecount %d, holdcnt %ld\n",
767 		    vp->v_flag, vp->v_usecount, vp->v_writecount, vp->v_holdcnt);
768 		printf("id %lu, mount %p, op %p\n",
769 		    vp->v_id, vp->v_mount, vp->v_op);
770 		printf("freef %p, freeb %p, mount %p\n",
771 		    vp->v_freelist.tqe_next, vp->v_freelist.tqe_prev,
772 		    vp->v_mount);
773 		printf("cleanblkhd %p, dirtyblkhd %p, numoutput %ld, type %d\n",
774 		    TAILQ_FIRST(&vp->v_cleanblkhd),
775 		    TAILQ_FIRST(&vp->v_dirtyblkhd),
776 		    vp->v_numoutput, vp->v_type);
777 		printf("union %p, tag %d, data[0] %08x, data[1] %08x\n",
778 		    vp->v_socket, vp->v_tag,
779 		    ((u_int *)vp->v_data)[0],
780 		    ((u_int *)vp->v_data)[1]);
781 	}
782 #endif
783 	error = VOP_CLOSE(pmp->pm_devvp,
784 		    (pmp->pm_flags&MSDOSFSMNT_RONLY) ? FREAD : FREAD | FWRITE,
785 		    NOCRED, p);
786 	vrele(pmp->pm_devvp);
787 	free(pmp->pm_inusemap, M_MSDOSFSFAT);
788 	free(pmp, M_MSDOSFSMNT);
789 	mp->mnt_data = (qaddr_t)0;
790 	mp->mnt_flag &= ~MNT_LOCAL;
791 	return (error);
792 }
793 
794 static int
795 msdosfs_root(mp, vpp)
796 	struct mount *mp;
797 	struct vnode **vpp;
798 {
799 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
800 	struct denode *ndep;
801 	int error;
802 
803 #ifdef MSDOSFS_DEBUG
804 	printf("msdosfs_root(); mp %p, pmp %p\n", mp, pmp);
805 #endif
806 	error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, &ndep);
807 	if (error)
808 		return (error);
809 	*vpp = DETOV(ndep);
810 	return (0);
811 }
812 
813 static int
814 msdosfs_statfs(mp, sbp, p)
815 	struct mount *mp;
816 	struct statfs *sbp;
817 	struct proc *p;
818 {
819 	struct msdosfsmount *pmp;
820 
821 	pmp = VFSTOMSDOSFS(mp);
822 	sbp->f_bsize = pmp->pm_bpcluster;
823 	sbp->f_iosize = pmp->pm_bpcluster;
824 	sbp->f_blocks = pmp->pm_maxcluster + 1;
825 	sbp->f_bfree = pmp->pm_freeclustercount;
826 	sbp->f_bavail = pmp->pm_freeclustercount;
827 	sbp->f_files = pmp->pm_RootDirEnts;			/* XXX */
828 	sbp->f_ffree = 0;	/* what to put in here? */
829 	if (sbp != &mp->mnt_stat) {
830 		sbp->f_type = mp->mnt_vfc->vfc_typenum;
831 		bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
832 		bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
833 	}
834 	strncpy(sbp->f_fstypename, mp->mnt_vfc->vfc_name, MFSNAMELEN);
835 	return (0);
836 }
837 
838 static int
839 msdosfs_sync(mp, waitfor, cred, p)
840 	struct mount *mp;
841 	int waitfor;
842 	struct ucred *cred;
843 	struct proc *p;
844 {
845 	struct vnode *vp, *nvp;
846 	struct denode *dep;
847 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
848 	int error, allerror = 0;
849 
850 	/*
851 	 * If we ever switch to not updating all of the fats all the time,
852 	 * this would be the place to update them from the first one.
853 	 */
854 	if (pmp->pm_fmod != 0) {
855 		if (pmp->pm_flags & MSDOSFSMNT_RONLY)
856 			panic("msdosfs_sync: rofs mod");
857 		else {
858 			/* update fats here */
859 		}
860 	}
861 	/*
862 	 * Write back each (modified) denode.
863 	 */
864 	simple_lock(&mntvnode_slock);
865 loop:
866 	for (vp = mp->mnt_vnodelist.lh_first; vp != NULL; vp = nvp) {
867 		/*
868 		 * If the vnode that we are about to sync is no longer
869 		 * associated with this mount point, start over.
870 		 */
871 		if (vp->v_mount != mp)
872 			goto loop;
873 
874 		simple_lock(&vp->v_interlock);
875 		nvp = vp->v_mntvnodes.le_next;
876 		dep = VTODE(vp);
877 		if (vp->v_type == VNON ||
878 		    ((dep->de_flag &
879 		    (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0 &&
880 		    (TAILQ_EMPTY(&vp->v_dirtyblkhd) || waitfor == MNT_LAZY))) {
881 			simple_unlock(&vp->v_interlock);
882 			continue;
883 		}
884 		simple_unlock(&mntvnode_slock);
885 		error = vget(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, p);
886 		if (error) {
887 			simple_lock(&mntvnode_slock);
888 			if (error == ENOENT)
889 				goto loop;
890 			continue;
891 		}
892 		error = VOP_FSYNC(vp, cred, waitfor, p);
893 		if (error)
894 			allerror = error;
895 		VOP_UNLOCK(vp, 0, p);
896 		vrele(vp);
897 		simple_lock(&mntvnode_slock);
898 	}
899 	simple_unlock(&mntvnode_slock);
900 
901 	/*
902 	 * Flush filesystem control info.
903 	 */
904 	if (waitfor != MNT_LAZY) {
905 		vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY, p);
906 		error = VOP_FSYNC(pmp->pm_devvp, cred, waitfor, p);
907 		if (error)
908 			allerror = error;
909 		VOP_UNLOCK(pmp->pm_devvp, 0, p);
910 	}
911 	return (allerror);
912 }
913 
914 static int
915 msdosfs_fhtovp(mp, fhp, vpp)
916 	struct mount *mp;
917 	struct fid *fhp;
918 	struct vnode **vpp;
919 {
920 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
921 	struct defid *defhp = (struct defid *) fhp;
922 	struct denode *dep;
923 	int error;
924 
925 	error = deget(pmp, defhp->defid_dirclust, defhp->defid_dirofs, &dep);
926 	if (error) {
927 		*vpp = NULLVP;
928 		return (error);
929 	}
930 	*vpp = DETOV(dep);
931 	return (0);
932 }
933 
934 static int
935 msdosfs_checkexp(mp, nam,  exflagsp, credanonp)
936 	struct mount *mp;
937 	struct sockaddr *nam;
938 	int *exflagsp;
939 	struct ucred **credanonp;
940 {
941 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
942 	struct netcred *np;
943 
944 	np = vfs_export_lookup(mp, &pmp->pm_export, nam);
945 	if (np == NULL)
946 		return (EACCES);
947 	*exflagsp = np->netc_exflags;
948 	*credanonp = &np->netc_anon;
949 	return (0);
950 }
951 
952 static int
953 msdosfs_vptofh(vp, fhp)
954 	struct vnode *vp;
955 	struct fid *fhp;
956 {
957 	struct denode *dep;
958 	struct defid *defhp;
959 
960 	dep = VTODE(vp);
961 	defhp = (struct defid *)fhp;
962 	defhp->defid_len = sizeof(struct defid);
963 	defhp->defid_dirclust = dep->de_dirclust;
964 	defhp->defid_dirofs = dep->de_diroffset;
965 	/* defhp->defid_gen = dep->de_gen; */
966 	return (0);
967 }
968 
969 static struct vfsops msdosfs_vfsops = {
970 	msdosfs_mount,
971 	vfs_stdstart,
972 	msdosfs_unmount,
973 	msdosfs_root,
974 	vfs_stdquotactl,
975 	msdosfs_statfs,
976 	msdosfs_sync,
977 	vfs_stdvget,
978 	msdosfs_fhtovp,
979 	msdosfs_checkexp,
980 	msdosfs_vptofh,
981 	msdosfs_init,
982 	vfs_stduninit,
983 	vfs_stdextattrctl,
984 };
985 
986 VFS_SET(msdosfs_vfsops, msdos, 0);
987