xref: /netbsd-src/sys/fs/msdosfs/msdosfs_vfsops.c (revision ce2c90c7c172d95d2402a5b3d96d8f8e6d138a21)
1 /*	$NetBSD: msdosfs_vfsops.c,v 1.36 2006/10/12 01:32:11 christos Exp $	*/
2 
3 /*-
4  * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
5  * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
6  * All rights reserved.
7  * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. All advertising materials mentioning features or use of this software
18  *    must display the following acknowledgement:
19  *	This product includes software developed by TooLs GmbH.
20  * 4. The name of TooLs GmbH may not be used to endorse or promote products
21  *    derived from this software without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
26  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
27  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
28  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
29  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
30  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
31  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
32  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33  */
34 /*
35  * Written by Paul Popelka (paulp@uts.amdahl.com)
36  *
37  * You can do anything you want with this software, just don't say you wrote
38  * it, and don't remove this notice.
39  *
40  * This software is provided "as is".
41  *
42  * The author supplies this software to be publicly redistributed on the
43  * understanding that the author is not responsible for the correct
44  * functioning of this software in any circumstances and is not liable for
45  * any damages caused by this software.
46  *
47  * October 1992
48  */
49 
50 #include <sys/cdefs.h>
51 __KERNEL_RCSID(0, "$NetBSD: msdosfs_vfsops.c,v 1.36 2006/10/12 01:32:11 christos Exp $");
52 
53 #if defined(_KERNEL_OPT)
54 #include "opt_quota.h"
55 #include "opt_compat_netbsd.h"
56 #endif
57 
58 #include <sys/param.h>
59 #include <sys/systm.h>
60 #include <sys/sysctl.h>
61 #include <sys/namei.h>
62 #include <sys/proc.h>
63 #include <sys/kernel.h>
64 #include <sys/vnode.h>
65 #include <miscfs/specfs/specdev.h> /* XXX */	/* defines v_rdev */
66 #include <sys/mount.h>
67 #include <sys/buf.h>
68 #include <sys/file.h>
69 #include <sys/device.h>
70 #include <sys/disklabel.h>
71 #include <sys/ioctl.h>
72 #include <sys/malloc.h>
73 #include <sys/dirent.h>
74 #include <sys/stat.h>
75 #include <sys/conf.h>
76 #include <sys/kauth.h>
77 
78 #include <fs/msdosfs/bpb.h>
79 #include <fs/msdosfs/bootsect.h>
80 #include <fs/msdosfs/direntry.h>
81 #include <fs/msdosfs/denode.h>
82 #include <fs/msdosfs/msdosfsmount.h>
83 #include <fs/msdosfs/fat.h>
84 
85 #define MSDOSFS_NAMEMAX(pmp) \
86 	(pmp)->pm_flags & MSDOSFSMNT_LONGNAME ? WIN_MAXLEN : 12
87 
88 int msdosfs_mountroot(void);
89 int msdosfs_mount(struct mount *, const char *, void *,
90     struct nameidata *, struct lwp *);
91 int msdosfs_start(struct mount *, int, struct lwp *);
92 int msdosfs_unmount(struct mount *, int, struct lwp *);
93 int msdosfs_root(struct mount *, struct vnode **);
94 int msdosfs_quotactl(struct mount *, int, uid_t, void *, struct lwp *);
95 int msdosfs_statvfs(struct mount *, struct statvfs *, struct lwp *);
96 int msdosfs_sync(struct mount *, int, kauth_cred_t, struct lwp *);
97 int msdosfs_vget(struct mount *, ino_t, struct vnode **);
98 int msdosfs_fhtovp(struct mount *, struct fid *, struct vnode **);
99 int msdosfs_vptofh(struct vnode *, struct fid *, size_t *fh_size);
100 
101 int msdosfs_mountfs(struct vnode *, struct mount *, struct lwp *,
102     struct msdosfs_args *);
103 
104 static int update_mp(struct mount *, struct msdosfs_args *);
105 
106 MALLOC_DEFINE(M_MSDOSFSMNT, "MSDOSFS mount", "MSDOS FS mount structure");
107 MALLOC_DEFINE(M_MSDOSFSFAT, "MSDOSFS fat", "MSDOS FS fat table");
108 
109 #define ROOTNAME "root_device"
110 
111 extern const struct vnodeopv_desc msdosfs_vnodeop_opv_desc;
112 
113 const struct vnodeopv_desc * const msdosfs_vnodeopv_descs[] = {
114 	&msdosfs_vnodeop_opv_desc,
115 	NULL,
116 };
117 
118 struct vfsops msdosfs_vfsops = {
119 	MOUNT_MSDOS,
120 	msdosfs_mount,
121 	msdosfs_start,
122 	msdosfs_unmount,
123 	msdosfs_root,
124 	msdosfs_quotactl,
125 	msdosfs_statvfs,
126 	msdosfs_sync,
127 	msdosfs_vget,
128 	msdosfs_fhtovp,
129 	msdosfs_vptofh,
130 	msdosfs_init,
131 	msdosfs_reinit,
132 	msdosfs_done,
133 	msdosfs_mountroot,
134 	(int (*)(struct mount *, struct vnode *, struct timespec *)) eopnotsupp,
135 	vfs_stdextattrctl,
136 	msdosfs_vnodeopv_descs,
137 	0,
138 	{ NULL, NULL },
139 };
140 VFS_ATTACH(msdosfs_vfsops);
141 
142 static int
143 update_mp(mp, argp)
144 	struct mount *mp;
145 	struct msdosfs_args *argp;
146 {
147 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
148 	int error;
149 
150 	pmp->pm_gid = argp->gid;
151 	pmp->pm_uid = argp->uid;
152 	pmp->pm_mask = argp->mask & ALLPERMS;
153 	pmp->pm_dirmask = argp->dirmask & ALLPERMS;
154 	pmp->pm_gmtoff = argp->gmtoff;
155 	pmp->pm_flags |= argp->flags & MSDOSFSMNT_MNTOPT;
156 
157 	/*
158 	 * GEMDOS knows nothing (yet) about win95
159 	 */
160 	if (pmp->pm_flags & MSDOSFSMNT_GEMDOSFS)
161 		pmp->pm_flags |= MSDOSFSMNT_NOWIN95;
162 
163 	if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
164 		pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
165 	else if (!(pmp->pm_flags &
166 	    (MSDOSFSMNT_SHORTNAME | MSDOSFSMNT_LONGNAME))) {
167 		struct vnode *rtvp;
168 
169 		/*
170 		 * Try to divine whether to support Win'95 long filenames
171 		 */
172 		if (FAT32(pmp))
173 			pmp->pm_flags |= MSDOSFSMNT_LONGNAME;
174 		else {
175 			if ((error = msdosfs_root(mp, &rtvp)) != 0)
176 				return error;
177 			pmp->pm_flags |= findwin95(VTODE(rtvp))
178 				? MSDOSFSMNT_LONGNAME
179 					: MSDOSFSMNT_SHORTNAME;
180 			vput(rtvp);
181 		}
182 	}
183 
184 	mp->mnt_stat.f_namemax = MSDOSFS_NAMEMAX(pmp);
185 
186 	return 0;
187 }
188 
189 int
190 msdosfs_mountroot()
191 {
192 	struct mount *mp;
193 	struct lwp *l = curlwp;	/* XXX */
194 	int error;
195 	struct msdosfs_args args;
196 
197 	if (device_class(root_device) != DV_DISK)
198 		return (ENODEV);
199 
200 	if ((error = vfs_rootmountalloc(MOUNT_MSDOS, "root_device", &mp))) {
201 		vrele(rootvp);
202 		return (error);
203 	}
204 
205 	args.flags = MSDOSFSMNT_VERSIONED;
206 	args.uid = 0;
207 	args.gid = 0;
208 	args.mask = 0777;
209 	args.version = MSDOSFSMNT_VERSION;
210 	args.dirmask = 0777;
211 
212 	if ((error = msdosfs_mountfs(rootvp, mp, l, &args)) != 0) {
213 		mp->mnt_op->vfs_refcount--;
214 		vfs_unbusy(mp);
215 		free(mp, M_MOUNT);
216 		return (error);
217 	}
218 
219 	if ((error = update_mp(mp, &args)) != 0) {
220 		(void)msdosfs_unmount(mp, 0, l);
221 		vfs_unbusy(mp);
222 		free(mp, M_MOUNT);
223 		vrele(rootvp);
224 		return (error);
225 	}
226 
227 	simple_lock(&mountlist_slock);
228 	CIRCLEQ_INSERT_TAIL(&mountlist, mp, mnt_list);
229 	simple_unlock(&mountlist_slock);
230 	(void)msdosfs_statvfs(mp, &mp->mnt_stat, l);
231 	vfs_unbusy(mp);
232 	return (0);
233 }
234 
235 /*
236  * mp - path - addr in user space of mount point (ie /usr or whatever)
237  * data - addr in user space of mount params including the name of the block
238  * special file to treat as a filesystem.
239  */
240 int
241 msdosfs_mount(mp, path, data, ndp, l)
242 	struct mount *mp;
243 	const char *path;
244 	void *data;
245 	struct nameidata *ndp;
246 	struct lwp *l;
247 {
248 	struct vnode *devvp;	  /* vnode for blk device to mount */
249 	struct msdosfs_args args; /* will hold data from mount request */
250 	/* msdosfs specific mount control block */
251 	struct msdosfsmount *pmp = NULL;
252 	int error, flags;
253 	mode_t accessmode;
254 
255 	if (mp->mnt_flag & MNT_GETARGS) {
256 		pmp = VFSTOMSDOSFS(mp);
257 		if (pmp == NULL)
258 			return EIO;
259 		args.fspec = NULL;
260 		args.uid = pmp->pm_uid;
261 		args.gid = pmp->pm_gid;
262 		args.mask = pmp->pm_mask;
263 		args.flags = pmp->pm_flags;
264 		args.version = MSDOSFSMNT_VERSION;
265 		args.dirmask = pmp->pm_dirmask;
266 		args.gmtoff = pmp->pm_gmtoff;
267 		return copyout(&args, data, sizeof(args));
268 	}
269 	error = copyin(data, &args, sizeof(struct msdosfs_args));
270 	if (error)
271 		return (error);
272 
273 	/*
274 	 * If not versioned (i.e. using old mount_msdos(8)), fill in
275 	 * the additional structure items with suitable defaults.
276 	 */
277 	if ((args.flags & MSDOSFSMNT_VERSIONED) == 0) {
278 		args.version = 1;
279 		args.dirmask = args.mask;
280 	}
281 
282 	/*
283 	 * Reset GMT offset for pre-v3 mount structure args.
284 	 */
285 	if (args.version < 3)
286 		args.gmtoff = 0;
287 
288 	/*
289 	 * If updating, check whether changing from read-only to
290 	 * read/write; if there is no device name, that's all we do.
291 	 */
292 	if (mp->mnt_flag & MNT_UPDATE) {
293 		pmp = VFSTOMSDOSFS(mp);
294 		error = 0;
295 		if (!(pmp->pm_flags & MSDOSFSMNT_RONLY) && (mp->mnt_flag & MNT_RDONLY)) {
296 			flags = WRITECLOSE;
297 			if (mp->mnt_flag & MNT_FORCE)
298 				flags |= FORCECLOSE;
299 			error = vflush(mp, NULLVP, flags);
300 		}
301 		if (!error && (mp->mnt_flag & MNT_RELOAD))
302 			/* not yet implemented */
303 			error = EOPNOTSUPP;
304 		if (error)
305 			return (error);
306 		if ((pmp->pm_flags & MSDOSFSMNT_RONLY) && (mp->mnt_iflag & IMNT_WANTRDWR)) {
307 			/*
308 			 * If upgrade to read-write by non-root, then verify
309 			 * that user has necessary permissions on the device.
310 			 */
311 			if (kauth_authorize_generic(l->l_cred,
312 			    KAUTH_GENERIC_ISSUSER, NULL) != 0) {
313 				devvp = pmp->pm_devvp;
314 				vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
315 				error = VOP_ACCESS(devvp, VREAD | VWRITE,
316 						   l->l_cred, l);
317 				VOP_UNLOCK(devvp, 0);
318 				if (error)
319 					return (error);
320 			}
321 			pmp->pm_flags &= ~MSDOSFSMNT_RONLY;
322 		}
323 		if (args.fspec == NULL)
324 			return EINVAL;
325 	}
326 	/*
327 	 * Not an update, or updating the name: look up the name
328 	 * and verify that it refers to a sensible block device.
329 	 */
330 	NDINIT(ndp, LOOKUP, FOLLOW, UIO_USERSPACE, args.fspec, l);
331 	if ((error = namei(ndp)) != 0)
332 		return (error);
333 	devvp = ndp->ni_vp;
334 
335 	if (devvp->v_type != VBLK) {
336 		vrele(devvp);
337 		return (ENOTBLK);
338 	}
339 	if (bdevsw_lookup(devvp->v_rdev) == NULL) {
340 		vrele(devvp);
341 		return (ENXIO);
342 	}
343 	/*
344 	 * If mount by non-root, then verify that user has necessary
345 	 * permissions on the device.
346 	 */
347 	if (kauth_authorize_generic(l->l_cred, KAUTH_GENERIC_ISSUSER, NULL) != 0) {
348 		accessmode = VREAD;
349 		if ((mp->mnt_flag & MNT_RDONLY) == 0)
350 			accessmode |= VWRITE;
351 		vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
352 		error = VOP_ACCESS(devvp, accessmode, l->l_cred, l);
353 		VOP_UNLOCK(devvp, 0);
354 		if (error) {
355 			vrele(devvp);
356 			return (error);
357 		}
358 	}
359 	if ((mp->mnt_flag & MNT_UPDATE) == 0) {
360 		int xflags;
361 
362 		/*
363 		 * Disallow multiple mounts of the same device.
364 		 * Disallow mounting of a device that is currently in use
365 		 * (except for root, which might share swap device for
366 		 * miniroot).
367 		 */
368 		error = vfs_mountedon(devvp);
369 		if (error)
370 			goto fail;
371 		if (vcount(devvp) > 1 && devvp != rootvp) {
372 			error = EBUSY;
373 			goto fail;
374 		}
375 		if (mp->mnt_flag & MNT_RDONLY)
376 			xflags = FREAD;
377 		else
378 			xflags = FREAD|FWRITE;
379 		error = VOP_OPEN(devvp, xflags, FSCRED, l);
380 		if (error)
381 			goto fail;
382 		error = msdosfs_mountfs(devvp, mp, l, &args);
383 		if (error) {
384 			vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
385 			(void) VOP_CLOSE(devvp, xflags, NOCRED, l);
386 			VOP_UNLOCK(devvp, 0);
387 			goto fail;
388 		}
389 #ifdef MSDOSFS_DEBUG		/* only needed for the printf below */
390 		pmp = VFSTOMSDOSFS(mp);
391 #endif
392 	} else {
393 		vrele(devvp);
394 		if (devvp != pmp->pm_devvp)
395 			return (EINVAL);	/* needs translation */
396 	}
397 	if ((error = update_mp(mp, &args)) != 0) {
398 		msdosfs_unmount(mp, MNT_FORCE, l);
399 		return error;
400 	}
401 
402 #ifdef MSDOSFS_DEBUG
403 	printf("msdosfs_mount(): mp %p, pmp %p, inusemap %p\n", mp, pmp, pmp->pm_inusemap);
404 #endif
405 	return set_statvfs_info(path, UIO_USERSPACE, args.fspec, UIO_USERSPACE,
406 	    mp, l);
407 
408 fail:
409 	vrele(devvp);
410 	return (error);
411 }
412 
413 int
414 msdosfs_mountfs(devvp, mp, l, argp)
415 	struct vnode *devvp;
416 	struct mount *mp;
417 	struct lwp *l;
418 	struct msdosfs_args *argp;
419 {
420 	struct msdosfsmount *pmp;
421 	struct buf *bp;
422 	dev_t dev = devvp->v_rdev;
423 	struct partinfo dpart;
424 	union bootsector *bsp;
425 	struct byte_bpb33 *b33;
426 	struct byte_bpb50 *b50;
427 	struct byte_bpb710 *b710;
428 	u_int8_t SecPerClust;
429 	int	ronly, error;
430 	int	bsize = 0, dtype = 0, tmp;
431 
432 	/* Flush out any old buffers remaining from a previous use. */
433 	if ((error = vinvalbuf(devvp, V_SAVE, l->l_cred, l, 0, 0)) != 0)
434 		return (error);
435 
436 	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
437 
438 	bp  = NULL; /* both used in error_exit */
439 	pmp = NULL;
440 
441 	if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
442 		/*
443 	 	 * We need the disklabel to calculate the size of a FAT entry
444 		 * later on. Also make sure the partition contains a filesystem
445 		 * of type FS_MSDOS. This doesn't work for floppies, so we have
446 		 * to check for them too.
447 	 	 *
448 	 	 * At least some parts of the msdos fs driver seem to assume
449 		 * that the size of a disk block will always be 512 bytes.
450 		 * Let's check it...
451 		 */
452 		error = VOP_IOCTL(devvp, DIOCGPART, &dpart, FREAD, NOCRED, l);
453 		if (error)
454 			goto error_exit;
455 		tmp   = dpart.part->p_fstype;
456 		dtype = dpart.disklab->d_type;
457 		bsize = dpart.disklab->d_secsize;
458 		if (bsize != 512 || (dtype!=DTYPE_FLOPPY && tmp!=FS_MSDOS)) {
459 			error = EINVAL;
460 			goto error_exit;
461 		}
462 	}
463 
464 	/*
465 	 * Read the boot sector of the filesystem, and then check the
466 	 * boot signature.  If not a dos boot sector then error out.
467 	 */
468 	if ((error = bread(devvp, 0, 512, NOCRED, &bp)) != 0)
469 		goto error_exit;
470 	bp->b_flags |= B_AGE;
471 	bsp = (union bootsector *)bp->b_data;
472 	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
473 	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
474 	b710 = (struct byte_bpb710 *)bsp->bs710.bsBPB;
475 
476 	if (!(argp->flags & MSDOSFSMNT_GEMDOSFS)) {
477 		if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
478 		    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
479 			error = EINVAL;
480 			goto error_exit;
481 		}
482 	}
483 
484 	pmp = malloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK);
485 	memset(pmp, 0, sizeof *pmp);
486 	pmp->pm_mountp = mp;
487 
488 	/*
489 	 * Compute several useful quantities from the bpb in the
490 	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
491 	 * the fields that are different between dos 5 and dos 3.3.
492 	 */
493 	SecPerClust = b50->bpbSecPerClust;
494 	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
495 	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
496 	pmp->pm_FATs = b50->bpbFATs;
497 	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
498 	pmp->pm_Sectors = getushort(b50->bpbSectors);
499 	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
500 	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
501 	pmp->pm_Heads = getushort(b50->bpbHeads);
502 	pmp->pm_Media = b50->bpbMedia;
503 
504 	if (!(argp->flags & MSDOSFSMNT_GEMDOSFS)) {
505 		/* XXX - We should probably check more values here */
506     		if (!pmp->pm_BytesPerSec || !SecPerClust
507 	    		|| pmp->pm_Heads > 255 || pmp->pm_SecPerTrack > 63) {
508 			error = EINVAL;
509 			goto error_exit;
510 		}
511 	}
512 
513 	if (pmp->pm_Sectors == 0) {
514 		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
515 		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
516 	} else {
517 		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
518 		pmp->pm_HugeSectors = pmp->pm_Sectors;
519 	}
520 
521 	if (pmp->pm_RootDirEnts == 0) {
522 		/*
523 		 * Some say that bsBootSectSig[23] must be zero, but
524 		 * Windows does not require this and some digital cameras
525 		 * do not set these to zero.  Therefore, do not insist.
526 		 */
527 		if (pmp->pm_Sectors
528 		    || pmp->pm_FATsecs
529 		    || getushort(b710->bpbFSVers)) {
530 			error = EINVAL;
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 
538 		/* mirrorring is enabled if the FATMIRROR bit is not set */
539 		if ((getushort(b710->bpbExtFlags) & FATMIRROR) == 0)
540 			pmp->pm_flags |= MSDOSFS_FATMIRROR;
541 		else
542 			pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
543 	} else
544 		pmp->pm_flags |= MSDOSFS_FATMIRROR;
545 
546 	if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
547 		if (FAT32(pmp)) {
548 			/*
549 			 * GEMDOS doesn't know fat32.
550 			 */
551 			error = EINVAL;
552 			goto error_exit;
553 		}
554 
555 		/*
556 		 * Check a few values (could do some more):
557 		 * - logical sector size: power of 2, >= block size
558 		 * - sectors per cluster: power of 2, >= 1
559 		 * - number of sectors:   >= 1, <= size of partition
560 		 */
561 		if ( (SecPerClust == 0)
562 		  || (SecPerClust & (SecPerClust - 1))
563 		  || (pmp->pm_BytesPerSec < bsize)
564 		  || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
565 		  || (pmp->pm_HugeSectors == 0)
566 		  || (pmp->pm_HugeSectors * (pmp->pm_BytesPerSec / bsize)
567 							> dpart.part->p_size)
568 		   ) {
569 			error = EINVAL;
570 			goto error_exit;
571 		}
572 		/*
573 		 * XXX - Many parts of the msdos fs driver seem to assume that
574 		 * the number of bytes per logical sector (BytesPerSec) will
575 		 * always be the same as the number of bytes per disk block
576 		 * Let's pretend it is.
577 		 */
578 		tmp = pmp->pm_BytesPerSec / bsize;
579 		pmp->pm_BytesPerSec  = bsize;
580 		pmp->pm_HugeSectors *= tmp;
581 		pmp->pm_HiddenSects *= tmp;
582 		pmp->pm_ResSectors  *= tmp;
583 		pmp->pm_Sectors     *= tmp;
584 		pmp->pm_FATsecs     *= tmp;
585 		SecPerClust         *= tmp;
586 	}
587 	pmp->pm_fatblk = pmp->pm_ResSectors;
588 	if (FAT32(pmp)) {
589 		pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
590 		pmp->pm_firstcluster = pmp->pm_fatblk
591 			+ (pmp->pm_FATs * pmp->pm_FATsecs);
592 		pmp->pm_fsinfo = getushort(b710->bpbFSInfo);
593 	} else {
594 		pmp->pm_rootdirblk = pmp->pm_fatblk +
595 			(pmp->pm_FATs * pmp->pm_FATsecs);
596 		pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
597 				       + pmp->pm_BytesPerSec - 1)
598 			/ pmp->pm_BytesPerSec;/* in sectors */
599 		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
600 	}
601 
602 	pmp->pm_nmbrofclusters = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
603 	    SecPerClust;
604 	pmp->pm_maxcluster = pmp->pm_nmbrofclusters + 1;
605 	pmp->pm_fatsize = pmp->pm_FATsecs * pmp->pm_BytesPerSec;
606 
607 	if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
608 		if (pmp->pm_nmbrofclusters <= (0xff0 - 2)
609 		      && (dtype == DTYPE_FLOPPY
610 			  || (dtype == DTYPE_VND
611 				&& (pmp->pm_Heads == 1 || pmp->pm_Heads == 2)))
612 		    ) {
613 			pmp->pm_fatmask = FAT12_MASK;
614 			pmp->pm_fatmult = 3;
615 			pmp->pm_fatdiv = 2;
616 		} else {
617 			pmp->pm_fatmask = FAT16_MASK;
618 			pmp->pm_fatmult = 2;
619 			pmp->pm_fatdiv = 1;
620 		}
621 	} else if (pmp->pm_fatmask == 0) {
622 		if (pmp->pm_maxcluster
623 		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
624 			/*
625 			 * This will usually be a floppy disk. This size makes
626 			 * sure that one fat entry will not be split across
627 			 * multiple blocks.
628 			 */
629 			pmp->pm_fatmask = FAT12_MASK;
630 			pmp->pm_fatmult = 3;
631 			pmp->pm_fatdiv = 2;
632 		} else {
633 			pmp->pm_fatmask = FAT16_MASK;
634 			pmp->pm_fatmult = 2;
635 			pmp->pm_fatdiv = 1;
636 		}
637 	}
638 	if (FAT12(pmp))
639 		pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
640 	else
641 		pmp->pm_fatblocksize = MAXBSIZE;
642 
643 	pmp->pm_fatblocksec = pmp->pm_fatblocksize / pmp->pm_BytesPerSec;
644 	pmp->pm_bnshift = ffs(pmp->pm_BytesPerSec) - 1;
645 
646 	/*
647 	 * Compute mask and shift value for isolating cluster relative byte
648 	 * offsets and cluster numbers from a file offset.
649 	 */
650 	pmp->pm_bpcluster = SecPerClust * pmp->pm_BytesPerSec;
651 	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
652 	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;
653 
654 	/*
655 	 * Check for valid cluster size
656 	 * must be a power of 2
657 	 */
658 	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
659 		error = EINVAL;
660 		goto error_exit;
661 	}
662 
663 	/*
664 	 * Release the bootsector buffer.
665 	 */
666 	brelse(bp);
667 	bp = NULL;
668 
669 	/*
670 	 * Check FSInfo.
671 	 */
672 	if (pmp->pm_fsinfo) {
673 		struct fsinfo *fp;
674 
675 		if ((error = bread(devvp, pmp->pm_fsinfo, 1024, NOCRED, &bp)) != 0)
676 			goto error_exit;
677 		fp = (struct fsinfo *)bp->b_data;
678 		if (!memcmp(fp->fsisig1, "RRaA", 4)
679 		    && !memcmp(fp->fsisig2, "rrAa", 4)
680 		    && !memcmp(fp->fsisig3, "\0\0\125\252", 4)
681 		    && !memcmp(fp->fsisig4, "\0\0\125\252", 4))
682 			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
683 		else
684 			pmp->pm_fsinfo = 0;
685 		brelse(bp);
686 		bp = NULL;
687 	}
688 
689 	/*
690 	 * Check and validate (or perhaps invalidate?) the fsinfo structure?
691 	 * XXX
692 	 */
693 	if (pmp->pm_fsinfo) {
694 		if (pmp->pm_nxtfree == (u_long)-1)
695 			pmp->pm_fsinfo = 0;
696 	}
697 
698 	/*
699 	 * Allocate memory for the bitmap of allocated clusters, and then
700 	 * fill it in.
701 	 */
702 	pmp->pm_inusemap = malloc(((pmp->pm_maxcluster + N_INUSEBITS - 1)
703 				   / N_INUSEBITS)
704 				  * sizeof(*pmp->pm_inusemap),
705 				  M_MSDOSFSFAT, M_WAITOK);
706 
707 	/*
708 	 * fillinusemap() needs pm_devvp.
709 	 */
710 	pmp->pm_dev = dev;
711 	pmp->pm_devvp = devvp;
712 
713 	/*
714 	 * Have the inuse map filled in.
715 	 */
716 	if ((error = fillinusemap(pmp)) != 0)
717 		goto error_exit;
718 
719 	/*
720 	 * If they want fat updates to be synchronous then let them suffer
721 	 * the performance degradation in exchange for the on disk copy of
722 	 * the fat being correct just about all the time.  I suppose this
723 	 * would be a good thing to turn on if the kernel is still flakey.
724 	 */
725 	if (mp->mnt_flag & MNT_SYNCHRONOUS)
726 		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;
727 
728 	/*
729 	 * Finish up.
730 	 */
731 	if (ronly)
732 		pmp->pm_flags |= MSDOSFSMNT_RONLY;
733 	else
734 		pmp->pm_fmod = 1;
735 	mp->mnt_data = pmp;
736 	mp->mnt_stat.f_fsidx.__fsid_val[0] = (long)dev;
737 	mp->mnt_stat.f_fsidx.__fsid_val[1] = makefstype(MOUNT_MSDOS);
738 	mp->mnt_stat.f_fsid = mp->mnt_stat.f_fsidx.__fsid_val[0];
739 	mp->mnt_stat.f_namemax = MSDOSFS_NAMEMAX(pmp);
740 	mp->mnt_flag |= MNT_LOCAL;
741 	mp->mnt_dev_bshift = pmp->pm_bnshift;
742 	mp->mnt_fs_bshift = pmp->pm_cnshift;
743 
744 #ifdef QUOTA
745 	/*
746 	 * If we ever do quotas for DOS filesystems this would be a place
747 	 * to fill in the info in the msdosfsmount structure. You dolt,
748 	 * quotas on dos filesystems make no sense because files have no
749 	 * owners on dos filesystems. of course there is some empty space
750 	 * in the directory entry where we could put uid's and gid's.
751 	 */
752 #endif
753 	devvp->v_specmountpoint = mp;
754 
755 	return (0);
756 
757 error_exit:;
758 	if (bp)
759 		brelse(bp);
760 	if (pmp) {
761 		if (pmp->pm_inusemap)
762 			free(pmp->pm_inusemap, M_MSDOSFSFAT);
763 		free(pmp, M_MSDOSFSMNT);
764 		mp->mnt_data = NULL;
765 	}
766 	return (error);
767 }
768 
769 int
770 msdosfs_start(struct mount *mp __unused, int flags __unused,
771     struct lwp *l __unused)
772 {
773 
774 	return (0);
775 }
776 
777 /*
778  * Unmount the filesystem described by mp.
779  */
780 int
781 msdosfs_unmount(mp, mntflags, l)
782 	struct mount *mp;
783 	int mntflags;
784 	struct lwp *l;
785 {
786 	struct msdosfsmount *pmp;
787 	int error, flags;
788 
789 	flags = 0;
790 	if (mntflags & MNT_FORCE)
791 		flags |= FORCECLOSE;
792 #ifdef QUOTA
793 #endif
794 	if ((error = vflush(mp, NULLVP, flags)) != 0)
795 		return (error);
796 	pmp = VFSTOMSDOSFS(mp);
797 	if (pmp->pm_devvp->v_type != VBAD)
798 		pmp->pm_devvp->v_specmountpoint = NULL;
799 #ifdef MSDOSFS_DEBUG
800 	{
801 		struct vnode *vp = pmp->pm_devvp;
802 
803 		printf("msdosfs_umount(): just before calling VOP_CLOSE()\n");
804 		printf("flag %08x, usecount %d, writecount %ld, holdcnt %ld\n",
805 		    vp->v_flag, vp->v_usecount, vp->v_writecount, vp->v_holdcnt);
806 		printf("mount %p, op %p\n",
807 		    vp->v_mount, vp->v_op);
808 		printf("freef %p, freeb %p, mount %p\n",
809 		    vp->v_freelist.tqe_next, vp->v_freelist.tqe_prev,
810 		    vp->v_mount);
811 		printf("cleanblkhd %p, dirtyblkhd %p, numoutput %d, type %d\n",
812 		    vp->v_cleanblkhd.lh_first,
813 		    vp->v_dirtyblkhd.lh_first,
814 		    vp->v_numoutput, vp->v_type);
815 		printf("union %p, tag %d, data[0] %08x, data[1] %08x\n",
816 		    vp->v_socket, vp->v_tag,
817 		    ((u_int *)vp->v_data)[0],
818 		    ((u_int *)vp->v_data)[1]);
819 	}
820 #endif
821 	vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY);
822 	error = VOP_CLOSE(pmp->pm_devvp,
823 	    pmp->pm_flags & MSDOSFSMNT_RONLY ? FREAD : FREAD|FWRITE, NOCRED, l);
824 	vput(pmp->pm_devvp);
825 	free(pmp->pm_inusemap, M_MSDOSFSFAT);
826 	free(pmp, M_MSDOSFSMNT);
827 	mp->mnt_data = NULL;
828 	mp->mnt_flag &= ~MNT_LOCAL;
829 	return (error);
830 }
831 
832 int
833 msdosfs_root(mp, vpp)
834 	struct mount *mp;
835 	struct vnode **vpp;
836 {
837 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
838 	struct denode *ndep;
839 	int error;
840 
841 #ifdef MSDOSFS_DEBUG
842 	printf("msdosfs_root(); mp %p, pmp %p\n", mp, pmp);
843 #endif
844 	if ((error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, &ndep)) != 0)
845 		return (error);
846 	*vpp = DETOV(ndep);
847 	return (0);
848 }
849 
850 int
851 msdosfs_quotactl(struct mount *mp __unused, int cmds __unused,
852     uid_t uid __unused, void *arg __unused, struct lwp *l __unused)
853 {
854 
855 	return (EOPNOTSUPP);
856 }
857 
858 int
859 msdosfs_statvfs(struct mount *mp, struct statvfs *sbp, struct lwp *l __unused)
860 {
861 	struct msdosfsmount *pmp;
862 
863 	pmp = VFSTOMSDOSFS(mp);
864 	sbp->f_bsize = pmp->pm_bpcluster;
865 	sbp->f_frsize = sbp->f_bsize;
866 	sbp->f_iosize = pmp->pm_bpcluster;
867 	sbp->f_blocks = pmp->pm_nmbrofclusters;
868 	sbp->f_bfree = pmp->pm_freeclustercount;
869 	sbp->f_bavail = pmp->pm_freeclustercount;
870 	sbp->f_bresvd = 0;
871 	sbp->f_files = pmp->pm_RootDirEnts;			/* XXX */
872 	sbp->f_ffree = 0;	/* what to put in here? */
873 	sbp->f_favail = 0;	/* what to put in here? */
874 	sbp->f_fresvd = 0;
875 	copy_statvfs_info(sbp, mp);
876 	return (0);
877 }
878 
879 int
880 msdosfs_sync(mp, waitfor, cred, l)
881 	struct mount *mp;
882 	int waitfor;
883 	kauth_cred_t cred;
884 	struct lwp *l;
885 {
886 	struct vnode *vp, *nvp;
887 	struct denode *dep;
888 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
889 	int error, allerror = 0;
890 
891 	/*
892 	 * If we ever switch to not updating all of the fats all the time,
893 	 * this would be the place to update them from the first one.
894 	 */
895 	if (pmp->pm_fmod != 0) {
896 		if (pmp->pm_flags & MSDOSFSMNT_RONLY)
897 			panic("msdosfs_sync: rofs mod");
898 		else {
899 			/* update fats here */
900 		}
901 	}
902 	/*
903 	 * Write back each (modified) denode.
904 	 */
905 	simple_lock(&mntvnode_slock);
906 loop:
907 	for (vp = mp->mnt_vnodelist.lh_first; vp != NULL; vp = nvp) {
908 		/*
909 		 * If the vnode that we are about to sync is no longer
910 		 * assoicated with this mount point, start over.
911 		 */
912 		if (vp->v_mount != mp)
913 			goto loop;
914 		simple_lock(&vp->v_interlock);
915 		nvp = vp->v_mntvnodes.le_next;
916 		dep = VTODE(vp);
917 		if (waitfor == MNT_LAZY || vp->v_type == VNON ||
918 		    (((dep->de_flag &
919 		    (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0) &&
920 		     (LIST_EMPTY(&vp->v_dirtyblkhd) &&
921 		      vp->v_uobj.uo_npages == 0))) {
922 			simple_unlock(&vp->v_interlock);
923 			continue;
924 		}
925 		simple_unlock(&mntvnode_slock);
926 		error = vget(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK);
927 		if (error) {
928 			simple_lock(&mntvnode_slock);
929 			if (error == ENOENT)
930 				goto loop;
931 			continue;
932 		}
933 		if ((error = VOP_FSYNC(vp, cred,
934 		    waitfor == MNT_WAIT ? FSYNC_WAIT : 0, 0, 0, l)) != 0)
935 			allerror = error;
936 		vput(vp);
937 		simple_lock(&mntvnode_slock);
938 	}
939 	simple_unlock(&mntvnode_slock);
940 	/*
941 	 * Force stale file system control information to be flushed.
942 	 */
943 	if ((error = VOP_FSYNC(pmp->pm_devvp, cred,
944 	    waitfor == MNT_WAIT ? FSYNC_WAIT : 0, 0, 0, l)) != 0)
945 		allerror = error;
946 #ifdef QUOTA
947 	/* qsync(mp); */
948 #endif
949 	return (allerror);
950 }
951 
952 int
953 msdosfs_fhtovp(mp, fhp, vpp)
954 	struct mount *mp;
955 	struct fid *fhp;
956 	struct vnode **vpp;
957 {
958 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
959 	struct defid defh;
960 	struct denode *dep;
961 	int error;
962 
963 	if (fhp->fid_len != sizeof(struct defid))
964 		return EINVAL;
965 
966 	memcpy(&defh, fhp, sizeof(defh));
967 	error = deget(pmp, defh.defid_dirclust, defh.defid_dirofs, &dep);
968 	if (error) {
969 		*vpp = NULLVP;
970 		return (error);
971 	}
972 	*vpp = DETOV(dep);
973 	return (0);
974 }
975 
976 int
977 msdosfs_vptofh(vp, fhp, fh_size)
978 	struct vnode *vp;
979 	struct fid *fhp;
980 	size_t *fh_size;
981 {
982 	struct denode *dep;
983 	struct defid defh;
984 
985 	if (*fh_size < sizeof(struct defid)) {
986 		*fh_size = sizeof(struct defid);
987 		return E2BIG;
988 	}
989 	*fh_size = sizeof(struct defid);
990 	dep = VTODE(vp);
991 	memset(&defh, 0, sizeof(defh));
992 	defh.defid_len = sizeof(struct defid);
993 	defh.defid_dirclust = dep->de_dirclust;
994 	defh.defid_dirofs = dep->de_diroffset;
995 	/* defh.defid_gen = dep->de_gen; */
996 	memcpy(fhp, &defh, sizeof(defh));
997 	return (0);
998 }
999 
1000 int
1001 msdosfs_vget(struct mount *mp __unused, ino_t ino __unused,
1002     struct vnode **vpp __unused)
1003 {
1004 
1005 	return (EOPNOTSUPP);
1006 }
1007 
1008 SYSCTL_SETUP(sysctl_vfs_msdosfs_setup, "sysctl vfs.msdosfs subtree setup")
1009 {
1010 
1011 	sysctl_createv(clog, 0, NULL, NULL,
1012 		       CTLFLAG_PERMANENT,
1013 		       CTLTYPE_NODE, "vfs", NULL,
1014 		       NULL, 0, NULL, 0,
1015 		       CTL_VFS, CTL_EOL);
1016 	sysctl_createv(clog, 0, NULL, NULL,
1017 		       CTLFLAG_PERMANENT,
1018 		       CTLTYPE_NODE, "msdosfs",
1019 		       SYSCTL_DESCR("MS-DOS file system"),
1020 		       NULL, 0, NULL, 0,
1021 		       CTL_VFS, 4, CTL_EOL);
1022 	/*
1023 	 * XXX the "4" above could be dynamic, thereby eliminating one
1024 	 * more instance of the "number to vfs" mapping problem, but
1025 	 * "4" is the order as taken from sys/mount.h
1026 	 */
1027 }
1028