xref: /netbsd-src/sys/fs/msdosfs/msdosfs_vfsops.c (revision 7f21db1c0118155e0dd40b75182e30c589d9f63e)
1 /*	$NetBSD: msdosfs_vfsops.c,v 1.79 2010/01/31 10:30:40 mlelstv 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 1.79 2010/01/31 10:30:40 mlelstv Exp $");
52 
53 #if defined(_KERNEL_OPT)
54 #include "opt_compat_netbsd.h"
55 #endif
56 
57 #include <sys/param.h>
58 #include <sys/systm.h>
59 #include <sys/sysctl.h>
60 #include <sys/namei.h>
61 #include <sys/proc.h>
62 #include <sys/kernel.h>
63 #include <sys/vnode.h>
64 #include <miscfs/genfs/genfs.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/disk.h>
72 #include <sys/ioctl.h>
73 #include <sys/malloc.h>
74 #include <sys/dirent.h>
75 #include <sys/stat.h>
76 #include <sys/conf.h>
77 #include <sys/kauth.h>
78 #include <sys/module.h>
79 
80 #include <fs/msdosfs/bpb.h>
81 #include <fs/msdosfs/bootsect.h>
82 #include <fs/msdosfs/direntry.h>
83 #include <fs/msdosfs/denode.h>
84 #include <fs/msdosfs/msdosfsmount.h>
85 #include <fs/msdosfs/fat.h>
86 
87 MODULE(MODULE_CLASS_VFS, msdosfs, NULL);
88 
89 #ifdef MSDOSFS_DEBUG
90 #define DPRINTF(a) uprintf a
91 #else
92 #define DPRINTF(a)
93 #endif
94 
95 #define MSDOSFS_NAMEMAX(pmp) \
96 	(pmp)->pm_flags & MSDOSFSMNT_LONGNAME ? WIN_MAXLEN : 12
97 
98 VFS_PROTOS(msdosfs);
99 
100 int msdosfs_mountfs(struct vnode *, struct mount *, struct lwp *,
101     struct msdosfs_args *);
102 
103 static int update_mp(struct mount *, struct msdosfs_args *);
104 
105 MALLOC_JUSTDEFINE(M_MSDOSFSMNT, "MSDOSFS mount", "MSDOS FS mount structure");
106 MALLOC_JUSTDEFINE(M_MSDOSFSFAT, "MSDOSFS fat", "MSDOS FS fat table");
107 MALLOC_JUSTDEFINE(M_MSDOSFSTMP, "MSDOSFS temp", "MSDOS FS temp. structures");
108 
109 #define ROOTNAME "root_device"
110 
111 static struct sysctllog *msdosfs_sysctl_log;
112 
113 extern const struct vnodeopv_desc msdosfs_vnodeop_opv_desc;
114 
115 const struct vnodeopv_desc * const msdosfs_vnodeopv_descs[] = {
116 	&msdosfs_vnodeop_opv_desc,
117 	NULL,
118 };
119 
120 struct vfsops msdosfs_vfsops = {
121 	MOUNT_MSDOS,
122 	sizeof (struct msdosfs_args),
123 	msdosfs_mount,
124 	msdosfs_start,
125 	msdosfs_unmount,
126 	msdosfs_root,
127 	(void *)eopnotsupp,		/* vfs_quotactl */
128 	msdosfs_statvfs,
129 	msdosfs_sync,
130 	msdosfs_vget,
131 	msdosfs_fhtovp,
132 	msdosfs_vptofh,
133 	msdosfs_init,
134 	msdosfs_reinit,
135 	msdosfs_done,
136 	msdosfs_mountroot,
137 	(int (*)(struct mount *, struct vnode *, struct timespec *)) eopnotsupp,
138 	vfs_stdextattrctl,
139 	(void *)eopnotsupp,		/* vfs_suspendctl */
140 	genfs_renamelock_enter,
141 	genfs_renamelock_exit,
142 	(void *)eopnotsupp,
143 	msdosfs_vnodeopv_descs,
144 	0,
145 	{ NULL, NULL },
146 };
147 
148 static int
149 msdosfs_modcmd(modcmd_t cmd, void *arg)
150 {
151 	int error;
152 
153 	switch (cmd) {
154 	case MODULE_CMD_INIT:
155 		error = vfs_attach(&msdosfs_vfsops);
156 		if (error != 0)
157 			break;
158 		sysctl_createv(&msdosfs_sysctl_log, 0, NULL, NULL,
159 			       CTLFLAG_PERMANENT,
160 			       CTLTYPE_NODE, "vfs", NULL,
161 			       NULL, 0, NULL, 0,
162 			       CTL_VFS, CTL_EOL);
163 		sysctl_createv(&msdosfs_sysctl_log, 0, NULL, NULL,
164 			       CTLFLAG_PERMANENT,
165 			       CTLTYPE_NODE, "msdosfs",
166 			       SYSCTL_DESCR("MS-DOS file system"),
167 			       NULL, 0, NULL, 0,
168 			       CTL_VFS, 4, CTL_EOL);
169 		/*
170 		 * XXX the "4" above could be dynamic, thereby eliminating one
171 		 * more instance of the "number to vfs" mapping problem, but
172 		 * "4" is the order as taken from sys/mount.h
173 		 */
174 		break;
175 	case MODULE_CMD_FINI:
176 		error = vfs_detach(&msdosfs_vfsops);
177 		if (error != 0)
178 			break;
179 		sysctl_teardown(&msdosfs_sysctl_log);
180 		break;
181 	default:
182 		error = ENOTTY;
183 		break;
184 	}
185 
186 	return (error);
187 }
188 
189 static int
190 update_mp(struct mount *mp, struct msdosfs_args *argp)
191 {
192 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
193 	int error;
194 
195 	pmp->pm_gid = argp->gid;
196 	pmp->pm_uid = argp->uid;
197 	pmp->pm_mask = argp->mask & ALLPERMS;
198 	pmp->pm_dirmask = argp->dirmask & ALLPERMS;
199 	pmp->pm_gmtoff = argp->gmtoff;
200 	pmp->pm_flags |= argp->flags & MSDOSFSMNT_MNTOPT;
201 
202 	/*
203 	 * GEMDOS knows nothing about win95 long filenames
204 	 */
205 	if (pmp->pm_flags & MSDOSFSMNT_GEMDOSFS)
206 		pmp->pm_flags |= MSDOSFSMNT_NOWIN95;
207 
208 	if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
209 		pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
210 	else if (!(pmp->pm_flags &
211 	    (MSDOSFSMNT_SHORTNAME | MSDOSFSMNT_LONGNAME))) {
212 		struct vnode *rtvp;
213 
214 		/*
215 		 * Try to divine whether to support Win'95 long filenames
216 		 */
217 		if (FAT32(pmp))
218 			pmp->pm_flags |= MSDOSFSMNT_LONGNAME;
219 		else {
220 			if ((error = msdosfs_root(mp, &rtvp)) != 0)
221 				return error;
222 			pmp->pm_flags |= findwin95(VTODE(rtvp))
223 				? MSDOSFSMNT_LONGNAME
224 					: MSDOSFSMNT_SHORTNAME;
225 			vput(rtvp);
226 		}
227 	}
228 
229 	mp->mnt_stat.f_namemax = MSDOSFS_NAMEMAX(pmp);
230 
231 	return 0;
232 }
233 
234 int
235 msdosfs_mountroot(void)
236 {
237 	struct mount *mp;
238 	struct lwp *l = curlwp;	/* XXX */
239 	int error;
240 	struct msdosfs_args args;
241 
242 	if (device_class(root_device) != DV_DISK)
243 		return (ENODEV);
244 
245 	if ((error = vfs_rootmountalloc(MOUNT_MSDOS, "root_device", &mp))) {
246 		vrele(rootvp);
247 		return (error);
248 	}
249 
250 	args.flags = MSDOSFSMNT_VERSIONED;
251 	args.uid = 0;
252 	args.gid = 0;
253 	args.mask = 0777;
254 	args.version = MSDOSFSMNT_VERSION;
255 	args.dirmask = 0777;
256 
257 	if ((error = msdosfs_mountfs(rootvp, mp, l, &args)) != 0) {
258 		vfs_unbusy(mp, false, NULL);
259 		vfs_destroy(mp);
260 		return (error);
261 	}
262 
263 	if ((error = update_mp(mp, &args)) != 0) {
264 		(void)msdosfs_unmount(mp, 0);
265 		vfs_unbusy(mp, false, NULL);
266 		vfs_destroy(mp);
267 		vrele(rootvp);
268 		return (error);
269 	}
270 
271 	mutex_enter(&mountlist_lock);
272 	CIRCLEQ_INSERT_TAIL(&mountlist, mp, mnt_list);
273 	mutex_exit(&mountlist_lock);
274 	(void)msdosfs_statvfs(mp, &mp->mnt_stat);
275 	vfs_unbusy(mp, false, NULL);
276 	return (0);
277 }
278 
279 /*
280  * mp - path - addr in user space of mount point (ie /usr or whatever)
281  * data - addr in user space of mount params including the name of the block
282  * special file to treat as a filesystem.
283  */
284 int
285 msdosfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
286 {
287 	struct lwp *l = curlwp;
288 	struct vnode *devvp;	  /* vnode for blk device to mount */
289 	struct msdosfs_args *args = data; /* holds data from mount request */
290 	/* msdosfs specific mount control block */
291 	struct msdosfsmount *pmp = NULL;
292 	int error, flags;
293 	mode_t accessmode;
294 
295 	if (*data_len < sizeof *args)
296 		return EINVAL;
297 
298 	if (mp->mnt_flag & MNT_GETARGS) {
299 		pmp = VFSTOMSDOSFS(mp);
300 		if (pmp == NULL)
301 			return EIO;
302 		args->fspec = NULL;
303 		args->uid = pmp->pm_uid;
304 		args->gid = pmp->pm_gid;
305 		args->mask = pmp->pm_mask;
306 		args->flags = pmp->pm_flags;
307 		args->version = MSDOSFSMNT_VERSION;
308 		args->dirmask = pmp->pm_dirmask;
309 		args->gmtoff = pmp->pm_gmtoff;
310 		*data_len = sizeof *args;
311 		return 0;
312 	}
313 
314 	/*
315 	 * If not versioned (i.e. using old mount_msdos(8)), fill in
316 	 * the additional structure items with suitable defaults.
317 	 */
318 	if ((args->flags & MSDOSFSMNT_VERSIONED) == 0) {
319 		args->version = 1;
320 		args->dirmask = args->mask;
321 	}
322 
323 	/*
324 	 * Reset GMT offset for pre-v3 mount structure args.
325 	 */
326 	if (args->version < 3)
327 		args->gmtoff = 0;
328 
329 	/*
330 	 * If updating, check whether changing from read-only to
331 	 * read/write; if there is no device name, that's all we do.
332 	 */
333 	if (mp->mnt_flag & MNT_UPDATE) {
334 		pmp = VFSTOMSDOSFS(mp);
335 		error = 0;
336 		if (!(pmp->pm_flags & MSDOSFSMNT_RONLY) &&
337 		    (mp->mnt_flag & MNT_RDONLY)) {
338 			flags = WRITECLOSE;
339 			if (mp->mnt_flag & MNT_FORCE)
340 				flags |= FORCECLOSE;
341 			error = vflush(mp, NULLVP, flags);
342 		}
343 		if (!error && (mp->mnt_flag & MNT_RELOAD))
344 			/* not yet implemented */
345 			error = EOPNOTSUPP;
346 		if (error) {
347 			DPRINTF(("vflush %d\n", error));
348 			return (error);
349 		}
350 		if ((pmp->pm_flags & MSDOSFSMNT_RONLY) &&
351 		    (mp->mnt_iflag & IMNT_WANTRDWR)) {
352 			/*
353 			 * If upgrade to read-write by non-root, then verify
354 			 * that user has necessary permissions on the device.
355 			 *
356 			 * Permission to update a mount is checked higher, so
357 			 * here we presume updating the mount is okay (for
358 			 * example, as far as securelevel goes) which leaves us
359 			 * with the normal check.
360 			 */
361 			devvp = pmp->pm_devvp;
362 			vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
363 			error = genfs_can_mount(devvp, VREAD | VWRITE,
364 			    l->l_cred);
365 			VOP_UNLOCK(devvp, 0);
366 			DPRINTF(("genfs_can_mount %d\n", error));
367 			if (error)
368 				return (error);
369 
370 			pmp->pm_flags &= ~MSDOSFSMNT_RONLY;
371 		}
372 		if (args->fspec == NULL) {
373 			DPRINTF(("missing fspec\n"));
374 			return EINVAL;
375 		}
376 	}
377 	/*
378 	 * Not an update, or updating the name: look up the name
379 	 * and verify that it refers to a sensible block device.
380 	 */
381 	error = namei_simple_user(args->fspec,
382 				NSM_FOLLOW_NOEMULROOT, &devvp);
383 	if (error != 0) {
384 		DPRINTF(("namei %d\n", error));
385 		return (error);
386 	}
387 
388 	if (devvp->v_type != VBLK) {
389 		DPRINTF(("not block\n"));
390 		vrele(devvp);
391 		return (ENOTBLK);
392 	}
393 	if (bdevsw_lookup(devvp->v_rdev) == NULL) {
394 		DPRINTF(("no block switch\n"));
395 		vrele(devvp);
396 		return (ENXIO);
397 	}
398 	/*
399 	 * If mount by non-root, then verify that user has necessary
400 	 * permissions on the device.
401 	 */
402 	accessmode = VREAD;
403 	if ((mp->mnt_flag & MNT_RDONLY) == 0)
404 		accessmode |= VWRITE;
405 	vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
406 	error = genfs_can_mount(devvp, accessmode, l->l_cred);
407 	VOP_UNLOCK(devvp, 0);
408 	if (error) {
409 		DPRINTF(("genfs_can_mount %d\n", error));
410 		vrele(devvp);
411 		return (error);
412 	}
413 	if ((mp->mnt_flag & MNT_UPDATE) == 0) {
414 		int xflags;
415 
416 		if (mp->mnt_flag & MNT_RDONLY)
417 			xflags = FREAD;
418 		else
419 			xflags = FREAD|FWRITE;
420 		error = VOP_OPEN(devvp, xflags, FSCRED);
421 		if (error) {
422 			DPRINTF(("VOP_OPEN %d\n", error));
423 			goto fail;
424 		}
425 		error = msdosfs_mountfs(devvp, mp, l, args);
426 		if (error) {
427 			DPRINTF(("msdosfs_mountfs %d\n", error));
428 			vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
429 			(void) VOP_CLOSE(devvp, xflags, NOCRED);
430 			VOP_UNLOCK(devvp, 0);
431 			goto fail;
432 		}
433 #ifdef MSDOSFS_DEBUG		/* only needed for the printf below */
434 		pmp = VFSTOMSDOSFS(mp);
435 #endif
436 	} else {
437 		vrele(devvp);
438 		if (devvp != pmp->pm_devvp) {
439 			DPRINTF(("devvp %p pmp %p\n",
440 			    devvp, pmp->pm_devvp));
441 			return (EINVAL);	/* needs translation */
442 		}
443 	}
444 	if ((error = update_mp(mp, args)) != 0) {
445 		msdosfs_unmount(mp, MNT_FORCE);
446 		DPRINTF(("update_mp %d\n", error));
447 		return error;
448 	}
449 
450 #ifdef MSDOSFS_DEBUG
451 	printf("msdosfs_mount(): mp %p, pmp %p, inusemap %p\n", mp, pmp, pmp->pm_inusemap);
452 #endif
453 	return set_statvfs_info(path, UIO_USERSPACE, args->fspec, UIO_USERSPACE,
454 	    mp->mnt_op->vfs_name, mp, l);
455 
456 fail:
457 	vrele(devvp);
458 	return (error);
459 }
460 
461 int
462 msdosfs_mountfs(struct vnode *devvp, struct mount *mp, struct lwp *l, struct msdosfs_args *argp)
463 {
464 	struct msdosfsmount *pmp;
465 	struct buf *bp;
466 	dev_t dev = devvp->v_rdev;
467 	union bootsector *bsp;
468 	struct byte_bpb33 *b33;
469 	struct byte_bpb50 *b50;
470 	struct byte_bpb710 *b710;
471 	uint8_t SecPerClust;
472 	int	ronly, error, tmp;
473 	int	bsize;
474 	uint64_t psize;
475 	unsigned secsize;
476 
477 	/* Flush out any old buffers remaining from a previous use. */
478 	if ((error = vinvalbuf(devvp, V_SAVE, l->l_cred, l, 0, 0)) != 0)
479 		return (error);
480 
481 	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
482 
483 	bp  = NULL; /* both used in error_exit */
484 	pmp = NULL;
485 
486 	error = getdisksize(devvp, &psize, &secsize);
487 	if (error)
488 		goto error_exit;
489 
490 	if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
491 		bsize = secsize;
492 		if (bsize != 512) {
493 			DPRINTF(("Invalid block bsize %d for gemdos\n", bsize));
494 			error = EINVAL;
495 			goto error_exit;
496 		}
497 	} else
498 		bsize = 0;
499 
500 	/*
501 	 * Read the boot sector of the filesystem, and then check the
502 	 * boot signature.  If not a dos boot sector then error out.
503 	 */
504 	if ((error = bread(devvp, 0, secsize, NOCRED, 0, &bp)) != 0)
505 		goto error_exit;
506 	bsp = (union bootsector *)bp->b_data;
507 	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
508 	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
509 	b710 = (struct byte_bpb710 *)bsp->bs710.bsBPB;
510 
511 	if (!(argp->flags & MSDOSFSMNT_GEMDOSFS)) {
512 		if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
513 		    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
514 			DPRINTF(("bootsig0 %d bootsig1 %d\n",
515 			    bsp->bs50.bsBootSectSig0,
516 			    bsp->bs50.bsBootSectSig1));
517 			error = EINVAL;
518 			goto error_exit;
519 		}
520 	}
521 
522 	pmp = malloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK);
523 	memset(pmp, 0, sizeof *pmp);
524 	pmp->pm_mountp = mp;
525 
526 	/*
527 	 * Compute several useful quantities from the bpb in the
528 	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
529 	 * the fields that are different between dos 5 and dos 3.3.
530 	 */
531 	SecPerClust = b50->bpbSecPerClust;
532 	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
533 	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
534 	pmp->pm_FATs = b50->bpbFATs;
535 	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
536 	pmp->pm_Sectors = getushort(b50->bpbSectors);
537 	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
538 	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
539 	pmp->pm_Heads = getushort(b50->bpbHeads);
540 	pmp->pm_Media = b50->bpbMedia;
541 
542 	if (!(argp->flags & MSDOSFSMNT_GEMDOSFS)) {
543 		/* XXX - We should probably check more values here */
544     		if (!pmp->pm_BytesPerSec || !SecPerClust
545 	    		|| pmp->pm_SecPerTrack > 63) {
546 			DPRINTF(("bytespersec %d secperclust %d "
547 			    "secpertrack %d\n",
548 			    pmp->pm_BytesPerSec, SecPerClust,
549 			    pmp->pm_SecPerTrack));
550 			error = EINVAL;
551 			goto error_exit;
552 		}
553 	}
554 
555 	if (pmp->pm_Sectors == 0) {
556 		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
557 		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
558 	} else {
559 		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
560 		pmp->pm_HugeSectors = pmp->pm_Sectors;
561 	}
562 
563 	if (pmp->pm_RootDirEnts == 0) {
564 		unsigned short vers = getushort(b710->bpbFSVers);
565 		/*
566 		 * Some say that bsBootSectSig[23] must be zero, but
567 		 * Windows does not require this and some digital cameras
568 		 * do not set these to zero.  Therefore, do not insist.
569 		 */
570 		if (pmp->pm_Sectors || pmp->pm_FATsecs || vers) {
571 			DPRINTF(("sectors %d fatsecs %lu vers %d\n",
572 			    pmp->pm_Sectors, pmp->pm_FATsecs, vers));
573 			error = EINVAL;
574 			goto error_exit;
575 		}
576 		pmp->pm_fatmask = FAT32_MASK;
577 		pmp->pm_fatmult = 4;
578 		pmp->pm_fatdiv = 1;
579 		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);
580 
581 		/* mirrorring is enabled if the FATMIRROR bit is not set */
582 		if ((getushort(b710->bpbExtFlags) & FATMIRROR) == 0)
583 			pmp->pm_flags |= MSDOSFS_FATMIRROR;
584 		else
585 			pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
586 	} else
587 		pmp->pm_flags |= MSDOSFS_FATMIRROR;
588 
589 	if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
590 		if (FAT32(pmp)) {
591 			DPRINTF(("fat32 for gemdos\n"));
592 			/*
593 			 * GEMDOS doesn't know fat32.
594 			 */
595 			error = EINVAL;
596 			goto error_exit;
597 		}
598 
599 		/*
600 		 * Check a few values (could do some more):
601 		 * - logical sector size: power of 2, >= block size
602 		 * - sectors per cluster: power of 2, >= 1
603 		 * - number of sectors:   >= 1, <= size of partition
604 		 */
605 		if ( (SecPerClust == 0)
606 		  || (SecPerClust & (SecPerClust - 1))
607 		  || (pmp->pm_BytesPerSec < bsize)
608 		  || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
609 		  || (pmp->pm_HugeSectors == 0)
610 		  || (pmp->pm_HugeSectors * (pmp->pm_BytesPerSec / bsize)
611 		      > psize)) {
612 			DPRINTF(("consistency checks for gemdos\n"));
613 			error = EINVAL;
614 			goto error_exit;
615 		}
616 		/*
617 		 * XXX - Many parts of the msdos fs driver seem to assume that
618 		 * the number of bytes per logical sector (BytesPerSec) will
619 		 * always be the same as the number of bytes per disk block
620 		 * Let's pretend it is.
621 		 */
622 		tmp = pmp->pm_BytesPerSec / bsize;
623 		pmp->pm_BytesPerSec  = bsize;
624 		pmp->pm_HugeSectors *= tmp;
625 		pmp->pm_HiddenSects *= tmp;
626 		pmp->pm_ResSectors  *= tmp;
627 		pmp->pm_Sectors     *= tmp;
628 		pmp->pm_FATsecs     *= tmp;
629 		SecPerClust         *= tmp;
630 	}
631 
632 	/* Check that fs has nonzero FAT size */
633 	if (pmp->pm_FATsecs == 0) {
634 		DPRINTF(("FATsecs is 0\n"));
635 		error = EINVAL;
636 		goto error_exit;
637 	}
638 
639 	pmp->pm_fatblk = pmp->pm_ResSectors;
640 	if (FAT32(pmp)) {
641 		pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
642 		pmp->pm_firstcluster = pmp->pm_fatblk
643 			+ (pmp->pm_FATs * pmp->pm_FATsecs);
644 		pmp->pm_fsinfo = getushort(b710->bpbFSInfo);
645 	} else {
646 		pmp->pm_rootdirblk = pmp->pm_fatblk +
647 			(pmp->pm_FATs * pmp->pm_FATsecs);
648 		pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
649 				       + pmp->pm_BytesPerSec - 1)
650 			/ pmp->pm_BytesPerSec;/* in sectors */
651 		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
652 	}
653 
654 	pmp->pm_nmbrofclusters = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
655 	    SecPerClust;
656 	pmp->pm_maxcluster = pmp->pm_nmbrofclusters + 1;
657 	pmp->pm_fatsize = pmp->pm_FATsecs * pmp->pm_BytesPerSec;
658 
659 	if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
660 		if (pmp->pm_nmbrofclusters <= (0xff0 - 2)) {
661 			pmp->pm_fatmask = FAT12_MASK;
662 			pmp->pm_fatmult = 3;
663 			pmp->pm_fatdiv = 2;
664 		} else {
665 			pmp->pm_fatmask = FAT16_MASK;
666 			pmp->pm_fatmult = 2;
667 			pmp->pm_fatdiv = 1;
668 		}
669 	} else if (pmp->pm_fatmask == 0) {
670 		if (pmp->pm_maxcluster
671 		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
672 			/*
673 			 * This will usually be a floppy disk. This size makes
674 			 * sure that one fat entry will not be split across
675 			 * multiple blocks.
676 			 */
677 			pmp->pm_fatmask = FAT12_MASK;
678 			pmp->pm_fatmult = 3;
679 			pmp->pm_fatdiv = 2;
680 		} else {
681 			pmp->pm_fatmask = FAT16_MASK;
682 			pmp->pm_fatmult = 2;
683 			pmp->pm_fatdiv = 1;
684 		}
685 	}
686 	if (FAT12(pmp))
687 		pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
688 	else
689 		pmp->pm_fatblocksize = MAXBSIZE;
690 
691 	pmp->pm_fatblocksec = pmp->pm_fatblocksize / pmp->pm_BytesPerSec;
692 	pmp->pm_bnshift = ffs(pmp->pm_BytesPerSec) - 1;
693 
694 	/*
695 	 * Compute mask and shift value for isolating cluster relative byte
696 	 * offsets and cluster numbers from a file offset.
697 	 */
698 	pmp->pm_bpcluster = SecPerClust * pmp->pm_BytesPerSec;
699 	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
700 	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;
701 
702 	/*
703 	 * Check for valid cluster size
704 	 * must be a power of 2
705 	 */
706 	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
707 		DPRINTF(("bpcluster %lu cnshift %lu\n",
708 		    pmp->pm_bpcluster, pmp->pm_cnshift));
709 		error = EINVAL;
710 		goto error_exit;
711 	}
712 
713 	/*
714 	 * Release the bootsector buffer.
715 	 */
716 	brelse(bp, BC_AGE);
717 	bp = NULL;
718 
719 	/*
720 	 * Check FSInfo.
721 	 */
722 	if (pmp->pm_fsinfo) {
723 		struct fsinfo *fp;
724 
725 		/*
726 		 * XXX	If the fsinfo block is stored on media with
727 		 *	2KB or larger sectors, is the fsinfo structure
728 		 *	padded at the end or in the middle?
729 		 */
730 		if ((error = bread(devvp, de_bn2kb(pmp, pmp->pm_fsinfo),
731 		    pmp->pm_BytesPerSec, NOCRED, 0, &bp)) != 0)
732 			goto error_exit;
733 		fp = (struct fsinfo *)bp->b_data;
734 		if (!memcmp(fp->fsisig1, "RRaA", 4)
735 		    && !memcmp(fp->fsisig2, "rrAa", 4)
736 		    && !memcmp(fp->fsisig3, "\0\0\125\252", 4)
737 		    && !memcmp(fp->fsisig4, "\0\0\125\252", 4))
738 			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
739 		else
740 			pmp->pm_fsinfo = 0;
741 		brelse(bp, 0);
742 		bp = NULL;
743 	}
744 
745 	/*
746 	 * Check and validate (or perhaps invalidate?) the fsinfo structure?
747 	 * XXX
748 	 */
749 	if (pmp->pm_fsinfo) {
750 		if (pmp->pm_nxtfree == (u_long)-1)
751 			pmp->pm_fsinfo = 0;
752 	}
753 
754 	/*
755 	 * Allocate memory for the bitmap of allocated clusters, and then
756 	 * fill it in.
757 	 */
758 	pmp->pm_inusemap = malloc(((pmp->pm_maxcluster + N_INUSEBITS - 1)
759 				   / N_INUSEBITS)
760 				  * sizeof(*pmp->pm_inusemap),
761 				  M_MSDOSFSFAT, M_WAITOK);
762 
763 	/*
764 	 * fillinusemap() needs pm_devvp.
765 	 */
766 	pmp->pm_dev = dev;
767 	pmp->pm_devvp = devvp;
768 
769 	/*
770 	 * Have the inuse map filled in.
771 	 */
772 	if ((error = fillinusemap(pmp)) != 0) {
773 		DPRINTF(("fillinusemap %d\n", error));
774 		goto error_exit;
775 	}
776 
777 	/*
778 	 * If they want fat updates to be synchronous then let them suffer
779 	 * the performance degradation in exchange for the on disk copy of
780 	 * the fat being correct just about all the time.  I suppose this
781 	 * would be a good thing to turn on if the kernel is still flakey.
782 	 */
783 	if (mp->mnt_flag & MNT_SYNCHRONOUS)
784 		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;
785 
786 	/*
787 	 * Finish up.
788 	 */
789 	if (ronly)
790 		pmp->pm_flags |= MSDOSFSMNT_RONLY;
791 	else
792 		pmp->pm_fmod = 1;
793 	mp->mnt_data = pmp;
794 	mp->mnt_stat.f_fsidx.__fsid_val[0] = (long)dev;
795 	mp->mnt_stat.f_fsidx.__fsid_val[1] = makefstype(MOUNT_MSDOS);
796 	mp->mnt_stat.f_fsid = mp->mnt_stat.f_fsidx.__fsid_val[0];
797 	mp->mnt_stat.f_namemax = MSDOSFS_NAMEMAX(pmp);
798 	mp->mnt_flag |= MNT_LOCAL;
799 	mp->mnt_dev_bshift = pmp->pm_bnshift;
800 	mp->mnt_fs_bshift = pmp->pm_cnshift;
801 
802 	/*
803 	 * If we ever do quotas for DOS filesystems this would be a place
804 	 * to fill in the info in the msdosfsmount structure. You dolt,
805 	 * quotas on dos filesystems make no sense because files have no
806 	 * owners on dos filesystems. of course there is some empty space
807 	 * in the directory entry where we could put uid's and gid's.
808 	 */
809 
810 	devvp->v_specmountpoint = mp;
811 
812 	return (0);
813 
814 error_exit:;
815 	if (bp)
816 		brelse(bp, BC_AGE);
817 	if (pmp) {
818 		if (pmp->pm_inusemap)
819 			free(pmp->pm_inusemap, M_MSDOSFSFAT);
820 		free(pmp, M_MSDOSFSMNT);
821 		mp->mnt_data = NULL;
822 	}
823 	return (error);
824 }
825 
826 int
827 msdosfs_start(struct mount *mp, int flags)
828 {
829 
830 	return (0);
831 }
832 
833 /*
834  * Unmount the filesystem described by mp.
835  */
836 int
837 msdosfs_unmount(struct mount *mp, int mntflags)
838 {
839 	struct msdosfsmount *pmp;
840 	int error, flags;
841 
842 	flags = 0;
843 	if (mntflags & MNT_FORCE)
844 		flags |= FORCECLOSE;
845 	if ((error = vflush(mp, NULLVP, flags)) != 0)
846 		return (error);
847 	pmp = VFSTOMSDOSFS(mp);
848 	if (pmp->pm_devvp->v_type != VBAD)
849 		pmp->pm_devvp->v_specmountpoint = NULL;
850 #ifdef MSDOSFS_DEBUG
851 	{
852 		struct vnode *vp = pmp->pm_devvp;
853 
854 		printf("msdosfs_umount(): just before calling VOP_CLOSE()\n");
855 		printf("flag %08x, usecount %d, writecount %d, holdcnt %d\n",
856 		    vp->v_vflag | vp->v_iflag | vp->v_uflag, vp->v_usecount,
857 		    vp->v_writecount, vp->v_holdcnt);
858 		printf("mount %p, op %p\n",
859 		    vp->v_mount, vp->v_op);
860 		printf("freef %p, freeb %p, mount %p\n",
861 		    vp->v_freelist.tqe_next, vp->v_freelist.tqe_prev,
862 		    vp->v_mount);
863 		printf("cleanblkhd %p, dirtyblkhd %p, numoutput %d, type %d\n",
864 		    vp->v_cleanblkhd.lh_first,
865 		    vp->v_dirtyblkhd.lh_first,
866 		    vp->v_numoutput, vp->v_type);
867 		printf("union %p, tag %d, data[0] %08x, data[1] %08x\n",
868 		    vp->v_socket, vp->v_tag,
869 		    ((u_int *)vp->v_data)[0],
870 		    ((u_int *)vp->v_data)[1]);
871 	}
872 #endif
873 	vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY);
874 	error = VOP_CLOSE(pmp->pm_devvp,
875 	    pmp->pm_flags & MSDOSFSMNT_RONLY ? FREAD : FREAD|FWRITE, NOCRED);
876 	vput(pmp->pm_devvp);
877 	free(pmp->pm_inusemap, M_MSDOSFSFAT);
878 	free(pmp, M_MSDOSFSMNT);
879 	mp->mnt_data = NULL;
880 	mp->mnt_flag &= ~MNT_LOCAL;
881 	return (error);
882 }
883 
884 int
885 msdosfs_root(struct mount *mp, struct vnode **vpp)
886 {
887 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
888 	struct denode *ndep;
889 	int error;
890 
891 #ifdef MSDOSFS_DEBUG
892 	printf("msdosfs_root(); mp %p, pmp %p\n", mp, pmp);
893 #endif
894 	if ((error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, &ndep)) != 0)
895 		return (error);
896 	*vpp = DETOV(ndep);
897 	return (0);
898 }
899 
900 int
901 msdosfs_statvfs(struct mount *mp, struct statvfs *sbp)
902 {
903 	struct msdosfsmount *pmp;
904 
905 	pmp = VFSTOMSDOSFS(mp);
906 	sbp->f_bsize = pmp->pm_bpcluster;
907 	sbp->f_frsize = sbp->f_bsize;
908 	sbp->f_iosize = pmp->pm_bpcluster;
909 	sbp->f_blocks = pmp->pm_nmbrofclusters;
910 	sbp->f_bfree = pmp->pm_freeclustercount;
911 	sbp->f_bavail = pmp->pm_freeclustercount;
912 	sbp->f_bresvd = 0;
913 	sbp->f_files = pmp->pm_RootDirEnts;			/* XXX */
914 	sbp->f_ffree = 0;	/* what to put in here? */
915 	sbp->f_favail = 0;	/* what to put in here? */
916 	sbp->f_fresvd = 0;
917 	copy_statvfs_info(sbp, mp);
918 	return (0);
919 }
920 
921 int
922 msdosfs_sync(struct mount *mp, int waitfor, kauth_cred_t cred)
923 {
924 	struct vnode *vp, *mvp;
925 	struct denode *dep;
926 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
927 	int error, allerror = 0;
928 
929 	/*
930 	 * If we ever switch to not updating all of the fats all the time,
931 	 * this would be the place to update them from the first one.
932 	 */
933 	if (pmp->pm_fmod != 0) {
934 		if (pmp->pm_flags & MSDOSFSMNT_RONLY)
935 			panic("msdosfs_sync: rofs mod");
936 		else {
937 			/* update fats here */
938 		}
939 	}
940 	/* Allocate a marker vnode. */
941 	if ((mvp = vnalloc(mp)) == NULL)
942 		return ENOMEM;
943 	/*
944 	 * Write back each (modified) denode.
945 	 */
946 	mutex_enter(&mntvnode_lock);
947 loop:
948 	for (vp = TAILQ_FIRST(&mp->mnt_vnodelist); vp; vp = vunmark(mvp)) {
949 		vmark(mvp, vp);
950 		if (vp->v_mount != mp || vismarker(vp))
951 			continue;
952 		mutex_enter(&vp->v_interlock);
953 		dep = VTODE(vp);
954 		if (waitfor == MNT_LAZY || vp->v_type == VNON ||
955 		    (((dep->de_flag &
956 		    (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0) &&
957 		     (LIST_EMPTY(&vp->v_dirtyblkhd) &&
958 		      UVM_OBJ_IS_CLEAN(&vp->v_uobj)))) {
959 			mutex_exit(&vp->v_interlock);
960 			continue;
961 		}
962 		mutex_exit(&mntvnode_lock);
963 		error = vget(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK);
964 		if (error) {
965 			mutex_enter(&mntvnode_lock);
966 			if (error == ENOENT) {
967 				(void)vunmark(mvp);
968 				goto loop;
969 			}
970 			continue;
971 		}
972 		if ((error = VOP_FSYNC(vp, cred,
973 		    waitfor == MNT_WAIT ? FSYNC_WAIT : 0, 0, 0)) != 0)
974 			allerror = error;
975 		vput(vp);
976 		mutex_enter(&mntvnode_lock);
977 	}
978 	mutex_exit(&mntvnode_lock);
979 	vnfree(mvp);
980 
981 	/*
982 	 * Force stale file system control information to be flushed.
983 	 */
984 	if ((error = VOP_FSYNC(pmp->pm_devvp, cred,
985 	    waitfor == MNT_WAIT ? FSYNC_WAIT : 0, 0, 0)) != 0)
986 		allerror = error;
987 	return (allerror);
988 }
989 
990 int
991 msdosfs_fhtovp(struct mount *mp, struct fid *fhp, struct vnode **vpp)
992 {
993 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
994 	struct defid defh;
995 	struct denode *dep;
996 	int error;
997 
998 	if (fhp->fid_len != sizeof(struct defid)) {
999 		DPRINTF(("fid_len %d %zd\n", fhp->fid_len,
1000 		    sizeof(struct defid)));
1001 		return EINVAL;
1002 	}
1003 
1004 	memcpy(&defh, fhp, sizeof(defh));
1005 	error = deget(pmp, defh.defid_dirclust, defh.defid_dirofs, &dep);
1006 	if (error) {
1007 		DPRINTF(("deget %d\n", error));
1008 		*vpp = NULLVP;
1009 		return (error);
1010 	}
1011 	*vpp = DETOV(dep);
1012 	return (0);
1013 }
1014 
1015 int
1016 msdosfs_vptofh(struct vnode *vp, struct fid *fhp, size_t *fh_size)
1017 {
1018 	struct denode *dep;
1019 	struct defid defh;
1020 
1021 	if (*fh_size < sizeof(struct defid)) {
1022 		*fh_size = sizeof(struct defid);
1023 		return E2BIG;
1024 	}
1025 	*fh_size = sizeof(struct defid);
1026 	dep = VTODE(vp);
1027 	memset(&defh, 0, sizeof(defh));
1028 	defh.defid_len = sizeof(struct defid);
1029 	defh.defid_dirclust = dep->de_dirclust;
1030 	defh.defid_dirofs = dep->de_diroffset;
1031 	/* defh.defid_gen = dep->de_gen; */
1032 	memcpy(fhp, &defh, sizeof(defh));
1033 	return (0);
1034 }
1035 
1036 int
1037 msdosfs_vget(struct mount *mp, ino_t ino,
1038     struct vnode **vpp)
1039 {
1040 
1041 	return (EOPNOTSUPP);
1042 }
1043