xref: /freebsd/sys/fs/msdosfs/msdosfs_vfsops.c (revision 830940567b49bb0c08dfaed40418999e76616909)
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/buf.h>
54 #include <sys/conf.h>
55 #include <sys/fcntl.h>
56 #include <sys/iconv.h>
57 #include <sys/kernel.h>
58 #include <sys/lock.h>
59 #include <sys/malloc.h>
60 #include <sys/mount.h>
61 #include <sys/mutex.h>
62 #include <sys/namei.h>
63 #include <sys/priv.h>
64 #include <sys/proc.h>
65 #include <sys/stat.h>
66 #include <sys/vnode.h>
67 
68 #include <geom/geom.h>
69 #include <geom/geom_vfs.h>
70 
71 #include <fs/msdosfs/bootsect.h>
72 #include <fs/msdosfs/bpb.h>
73 #include <fs/msdosfs/direntry.h>
74 #include <fs/msdosfs/denode.h>
75 #include <fs/msdosfs/fat.h>
76 #include <fs/msdosfs/msdosfsmount.h>
77 
78 /* Mount options that we support. */
79 static const char *msdosfs_opts[] = {
80 	"async", "noatime", "noclusterr", "noclusterw",
81 	"export", "force", "from", "sync",
82 	"cs_dos", "cs_local", "cs_win", "dirmask",
83 	"gid", "kiconv", "large", "longname",
84 	"longnames", "mask", "shortname", "shortnames",
85 	"uid", "win95", "nowin95",
86 	NULL
87 };
88 
89 #if 1 /*def PC98*/
90 /*
91  * XXX - The boot signature formatted by NEC PC-98 DOS looks like a
92  *       garbage or a random value :-{
93  *       If you want to use that broken-signatured media, define the
94  *       following symbol even though PC/AT.
95  *       (ex. mount PC-98 DOS formatted FD on PC/AT)
96  */
97 #define	MSDOSFS_NOCHECKSIG
98 #endif
99 
100 MALLOC_DEFINE(M_MSDOSFSMNT, "msdosfs_mount", "MSDOSFS mount structure");
101 static MALLOC_DEFINE(M_MSDOSFSFAT, "msdosfs_fat", "MSDOSFS file allocation table");
102 
103 struct iconv_functions *msdosfs_iconv;
104 
105 static int	update_mp(struct mount *mp, struct thread *td);
106 static int	mountmsdosfs(struct vnode *devvp, struct mount *mp);
107 static vfs_fhtovp_t	msdosfs_fhtovp;
108 static vfs_mount_t	msdosfs_mount;
109 static vfs_root_t	msdosfs_root;
110 static vfs_statfs_t	msdosfs_statfs;
111 static vfs_sync_t	msdosfs_sync;
112 static vfs_unmount_t	msdosfs_unmount;
113 
114 /* Maximum length of a character set name (arbitrary). */
115 #define	MAXCSLEN	64
116 
117 static int
118 update_mp(struct mount *mp, struct thread *td)
119 {
120 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
121 	void *dos, *win, *local;
122 	int error, v;
123 
124 	if (!vfs_getopt(mp->mnt_optnew, "kiconv", NULL, NULL)) {
125 		if (msdosfs_iconv != NULL) {
126 			error = vfs_getopt(mp->mnt_optnew,
127 			    "cs_win", &win, NULL);
128 			if (!error)
129 				error = vfs_getopt(mp->mnt_optnew,
130 				    "cs_local", &local, NULL);
131 			if (!error)
132 				error = vfs_getopt(mp->mnt_optnew,
133 				    "cs_dos", &dos, NULL);
134 			if (!error) {
135 				msdosfs_iconv->open(win, local, &pmp->pm_u2w);
136 				msdosfs_iconv->open(local, win, &pmp->pm_w2u);
137 				msdosfs_iconv->open(dos, local, &pmp->pm_u2d);
138 				msdosfs_iconv->open(local, dos, &pmp->pm_d2u);
139 			}
140 			if (error != 0)
141 				return (error);
142 		} else {
143 			pmp->pm_w2u = NULL;
144 			pmp->pm_u2w = NULL;
145 			pmp->pm_d2u = NULL;
146 			pmp->pm_u2d = NULL;
147 		}
148 	}
149 
150 	if (1 == vfs_scanopt(mp->mnt_optnew, "gid", "%d", &v))
151 		pmp->pm_gid = v;
152 	if (1 == vfs_scanopt(mp->mnt_optnew, "uid", "%d", &v))
153 		pmp->pm_uid = v;
154 	if (1 == vfs_scanopt(mp->mnt_optnew, "mask", "%d", &v))
155 		pmp->pm_mask = v & ALLPERMS;
156 	if (1 == vfs_scanopt(mp->mnt_optnew, "dirmask", "%d", &v))
157 		pmp->pm_dirmask = v & ALLPERMS;
158 	vfs_flagopt(mp->mnt_optnew, "shortname",
159 	    &pmp->pm_flags, MSDOSFSMNT_SHORTNAME);
160 	vfs_flagopt(mp->mnt_optnew, "shortnames",
161 	    &pmp->pm_flags, MSDOSFSMNT_SHORTNAME);
162 	vfs_flagopt(mp->mnt_optnew, "longname",
163 	    &pmp->pm_flags, MSDOSFSMNT_LONGNAME);
164 	vfs_flagopt(mp->mnt_optnew, "longnames",
165 	    &pmp->pm_flags, MSDOSFSMNT_LONGNAME);
166 	vfs_flagopt(mp->mnt_optnew, "kiconv",
167 	    &pmp->pm_flags, MSDOSFSMNT_KICONV);
168 
169 	if (vfs_getopt(mp->mnt_optnew, "nowin95", NULL, NULL) == 0)
170 		pmp->pm_flags |= MSDOSFSMNT_NOWIN95;
171 	else
172 		pmp->pm_flags &= ~MSDOSFSMNT_NOWIN95;
173 
174 	if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
175 		pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
176 	else if (!(pmp->pm_flags &
177 	    (MSDOSFSMNT_SHORTNAME | MSDOSFSMNT_LONGNAME))) {
178 		struct vnode *rootvp;
179 
180 		/*
181 		 * Try to divine whether to support Win'95 long filenames
182 		 */
183 		if (FAT32(pmp))
184 			pmp->pm_flags |= MSDOSFSMNT_LONGNAME;
185 		else {
186 			if ((error =
187 			    msdosfs_root(mp, LK_EXCLUSIVE, &rootvp)) != 0)
188 				return error;
189 			pmp->pm_flags |= findwin95(VTODE(rootvp)) ?
190 			    MSDOSFSMNT_LONGNAME : MSDOSFSMNT_SHORTNAME;
191 			vput(rootvp);
192 		}
193 	}
194 	return 0;
195 }
196 
197 static int
198 msdosfs_cmount(struct mntarg *ma, void *data, int flags)
199 {
200 	struct msdosfs_args args;
201 	int error;
202 
203 	if (data == NULL)
204 		return (EINVAL);
205 	error = copyin(data, &args, sizeof args);
206 	if (error)
207 		return (error);
208 
209 	ma = mount_argsu(ma, "from", args.fspec, MAXPATHLEN);
210 	ma = mount_arg(ma, "export", &args.export, sizeof args.export);
211 	ma = mount_argf(ma, "uid", "%d", args.uid);
212 	ma = mount_argf(ma, "gid", "%d", args.gid);
213 	ma = mount_argf(ma, "mask", "%d", args.mask);
214 	ma = mount_argf(ma, "dirmask", "%d", args.dirmask);
215 
216 	ma = mount_argb(ma, args.flags & MSDOSFSMNT_SHORTNAME, "noshortname");
217 	ma = mount_argb(ma, args.flags & MSDOSFSMNT_LONGNAME, "nolongname");
218 	ma = mount_argb(ma, !(args.flags & MSDOSFSMNT_NOWIN95), "nowin95");
219 	ma = mount_argb(ma, args.flags & MSDOSFSMNT_KICONV, "nokiconv");
220 
221 	ma = mount_argsu(ma, "cs_win", args.cs_win, MAXCSLEN);
222 	ma = mount_argsu(ma, "cs_dos", args.cs_dos, MAXCSLEN);
223 	ma = mount_argsu(ma, "cs_local", args.cs_local, MAXCSLEN);
224 
225 	error = kernel_mount(ma, flags);
226 
227 	return (error);
228 }
229 
230 /*
231  * mp - path - addr in user space of mount point (ie /usr or whatever)
232  * data - addr in user space of mount params including the name of the block
233  * special file to treat as a filesystem.
234  */
235 static int
236 msdosfs_mount(struct mount *mp)
237 {
238 	struct vnode *devvp;	  /* vnode for blk device to mount */
239 	struct thread *td;
240 	/* msdosfs specific mount control block */
241 	struct msdosfsmount *pmp = NULL;
242 	struct nameidata ndp;
243 	int error, flags;
244 	accmode_t accmode;
245 	char *from;
246 
247 	td = curthread;
248 	if (vfs_filteropt(mp->mnt_optnew, msdosfs_opts))
249 		return (EINVAL);
250 
251 	/*
252 	 * If updating, check whether changing from read-only to
253 	 * read/write; if there is no device name, that's all we do.
254 	 */
255 	if (mp->mnt_flag & MNT_UPDATE) {
256 		pmp = VFSTOMSDOSFS(mp);
257 		if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) {
258 			/*
259 			 * Forbid export requests if filesystem has
260 			 * MSDOSFS_LARGEFS flag set.
261 			 */
262 			if ((pmp->pm_flags & MSDOSFS_LARGEFS) != 0) {
263 				vfs_mount_error(mp,
264 				    "MSDOSFS_LARGEFS flag set, cannot export");
265 				return (EOPNOTSUPP);
266 			}
267 		}
268 		if (!(pmp->pm_flags & MSDOSFSMNT_RONLY) &&
269 		    vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0)) {
270 			error = VFS_SYNC(mp, MNT_WAIT);
271 			if (error)
272 				return (error);
273 			flags = WRITECLOSE;
274 			if (mp->mnt_flag & MNT_FORCE)
275 				flags |= FORCECLOSE;
276 			error = vflush(mp, 0, flags, td);
277 			if (error)
278 				return (error);
279 
280 			/*
281 			 * Now the volume is clean.  Mark it so while the
282 			 * device is still rw.
283 			 */
284 			error = markvoldirty(pmp, 0);
285 			if (error) {
286 				(void)markvoldirty(pmp, 1);
287 				return (error);
288 			}
289 
290 			/* Downgrade the device from rw to ro. */
291 			DROP_GIANT();
292 			g_topology_lock();
293 			error = g_access(pmp->pm_cp, 0, -1, 0);
294 			g_topology_unlock();
295 			PICKUP_GIANT();
296 			if (error) {
297 				(void)markvoldirty(pmp, 1);
298 				return (error);
299 			}
300 
301 			/*
302 			 * Backing out after an error was painful in the
303 			 * above.  Now we are committed to succeeding.
304 			 */
305 			pmp->pm_fmod = 0;
306 			pmp->pm_flags |= MSDOSFSMNT_RONLY;
307 			MNT_ILOCK(mp);
308 			mp->mnt_flag |= MNT_RDONLY;
309 			MNT_IUNLOCK(mp);
310 		} else if ((pmp->pm_flags & MSDOSFSMNT_RONLY) &&
311 		    !vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0)) {
312 			/*
313 			 * If upgrade to read-write by non-root, then verify
314 			 * that user has necessary permissions on the device.
315 			 */
316 			devvp = pmp->pm_devvp;
317 			vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
318 			error = VOP_ACCESS(devvp, VREAD | VWRITE,
319 			    td->td_ucred, td);
320 			if (error)
321 				error = priv_check(td, PRIV_VFS_MOUNT_PERM);
322 			if (error) {
323 				VOP_UNLOCK(devvp, 0);
324 				return (error);
325 			}
326 			VOP_UNLOCK(devvp, 0);
327 			DROP_GIANT();
328 			g_topology_lock();
329 			error = g_access(pmp->pm_cp, 0, 1, 0);
330 			g_topology_unlock();
331 			PICKUP_GIANT();
332 			if (error)
333 				return (error);
334 
335 			pmp->pm_fmod = 1;
336 			pmp->pm_flags &= ~MSDOSFSMNT_RONLY;
337 			MNT_ILOCK(mp);
338 			mp->mnt_flag &= ~MNT_RDONLY;
339 			MNT_IUNLOCK(mp);
340 
341 			/* Now that the volume is modifiable, mark it dirty. */
342 			error = markvoldirty(pmp, 1);
343 			if (error)
344 				return (error);
345 		}
346 	}
347 	/*
348 	 * Not an update, or updating the name: look up the name
349 	 * and verify that it refers to a sensible disk device.
350 	 */
351 	if (vfs_getopt(mp->mnt_optnew, "from", (void **)&from, NULL))
352 		return (EINVAL);
353 	NDINIT(&ndp, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, from, td);
354 	error = namei(&ndp);
355 	if (error)
356 		return (error);
357 	devvp = ndp.ni_vp;
358 	NDFREE(&ndp, NDF_ONLY_PNBUF);
359 
360 	if (!vn_isdisk(devvp, &error)) {
361 		vput(devvp);
362 		return (error);
363 	}
364 	/*
365 	 * If mount by non-root, then verify that user has necessary
366 	 * permissions on the device.
367 	 */
368 	accmode = VREAD;
369 	if ((mp->mnt_flag & MNT_RDONLY) == 0)
370 		accmode |= VWRITE;
371 	error = VOP_ACCESS(devvp, accmode, td->td_ucred, td);
372 	if (error)
373 		error = priv_check(td, PRIV_VFS_MOUNT_PERM);
374 	if (error) {
375 		vput(devvp);
376 		return (error);
377 	}
378 	if ((mp->mnt_flag & MNT_UPDATE) == 0) {
379 		error = mountmsdosfs(devvp, mp);
380 #ifdef MSDOSFS_DEBUG		/* only needed for the printf below */
381 		pmp = VFSTOMSDOSFS(mp);
382 #endif
383 	} else {
384 		if (devvp != pmp->pm_devvp)
385 			error = EINVAL;	/* XXX needs translation */
386 		else
387 			vput(devvp);
388 	}
389 	if (error) {
390 		vrele(devvp);
391 		return (error);
392 	}
393 
394 	error = update_mp(mp, td);
395 	if (error) {
396 		if ((mp->mnt_flag & MNT_UPDATE) == 0)
397 			msdosfs_unmount(mp, MNT_FORCE);
398 		return error;
399 	}
400 
401 	vfs_mountedfrom(mp, from);
402 #ifdef MSDOSFS_DEBUG
403 	printf("msdosfs_mount(): mp %p, pmp %p, inusemap %p\n", mp, pmp, pmp->pm_inusemap);
404 #endif
405 	return (0);
406 }
407 
408 static int
409 mountmsdosfs(struct vnode *devvp, struct mount *mp)
410 {
411 	struct msdosfsmount *pmp;
412 	struct buf *bp;
413 	struct cdev *dev;
414 	union bootsector *bsp;
415 	struct byte_bpb33 *b33;
416 	struct byte_bpb50 *b50;
417 	struct byte_bpb710 *b710;
418 	u_int8_t SecPerClust;
419 	u_long clusters;
420 	int ronly, error;
421 	struct g_consumer *cp;
422 	struct bufobj *bo;
423 
424 	bp = NULL;		/* This and pmp both used in error_exit. */
425 	pmp = NULL;
426 	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
427 
428 	dev = devvp->v_rdev;
429 	dev_ref(dev);
430 	DROP_GIANT();
431 	g_topology_lock();
432 	error = g_vfs_open(devvp, &cp, "msdosfs", ronly ? 0 : 1);
433 	g_topology_unlock();
434 	PICKUP_GIANT();
435 	VOP_UNLOCK(devvp, 0);
436 	if (error)
437 		goto error_exit;
438 
439 	bo = &devvp->v_bufobj;
440 
441 	/*
442 	 * Read the boot sector of the filesystem, and then check the
443 	 * boot signature.  If not a dos boot sector then error out.
444 	 *
445 	 * NOTE: 8192 is a magic size that works for ffs.
446 	 */
447 	error = bread(devvp, 0, 8192, NOCRED, &bp);
448 	if (error)
449 		goto error_exit;
450 	bp->b_flags |= B_AGE;
451 	bsp = (union bootsector *)bp->b_data;
452 	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
453 	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
454 	b710 = (struct byte_bpb710 *)bsp->bs710.bsBPB;
455 
456 #ifndef MSDOSFS_NOCHECKSIG
457 	if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
458 	    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
459 		error = EINVAL;
460 		goto error_exit;
461 	}
462 #endif
463 
464 	pmp = malloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK | M_ZERO);
465 	pmp->pm_mountp = mp;
466 	pmp->pm_cp = cp;
467 	pmp->pm_bo = bo;
468 
469 	/*
470 	 * Initialize ownerships and permissions, since nothing else will
471 	 * initialize them iff we are mounting root.
472 	 */
473 	pmp->pm_uid = UID_ROOT;
474 	pmp->pm_gid = GID_WHEEL;
475 	pmp->pm_mask = pmp->pm_dirmask = S_IXUSR | S_IXGRP | S_IXOTH |
476 	    S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR;
477 
478 	/*
479 	 * Experimental support for large MS-DOS filesystems.
480 	 * WARNING: This uses at least 32 bytes of kernel memory (which is not
481 	 * reclaimed until the FS is unmounted) for each file on disk to map
482 	 * between the 32-bit inode numbers used by VFS and the 64-bit
483 	 * pseudo-inode numbers used internally by msdosfs. This is only
484 	 * safe to use in certain controlled situations (e.g. read-only FS
485 	 * with less than 1 million files).
486 	 * Since the mappings do not persist across unmounts (or reboots), these
487 	 * filesystems are not suitable for exporting through NFS, or any other
488 	 * application that requires fixed inode numbers.
489 	 */
490 	vfs_flagopt(mp->mnt_optnew, "large", &pmp->pm_flags, MSDOSFS_LARGEFS);
491 
492 	/*
493 	 * Compute several useful quantities from the bpb in the
494 	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
495 	 * the fields that are different between dos 5 and dos 3.3.
496 	 */
497 	SecPerClust = b50->bpbSecPerClust;
498 	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
499 	if (pmp->pm_BytesPerSec < DEV_BSIZE) {
500 		error = EINVAL;
501 		goto error_exit;
502 	}
503 	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
504 	pmp->pm_FATs = b50->bpbFATs;
505 	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
506 	pmp->pm_Sectors = getushort(b50->bpbSectors);
507 	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
508 	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
509 	pmp->pm_Heads = getushort(b50->bpbHeads);
510 	pmp->pm_Media = b50->bpbMedia;
511 
512 	/* calculate the ratio of sector size to DEV_BSIZE */
513 	pmp->pm_BlkPerSec = pmp->pm_BytesPerSec / DEV_BSIZE;
514 
515 	/*
516 	 * We don't check pm_Heads nor pm_SecPerTrack, because
517 	 * these may not be set for EFI file systems. We don't
518 	 * use these anyway, so we're unaffected if they are
519 	 * invalid.
520 	 */
521 	if (!pmp->pm_BytesPerSec || !SecPerClust) {
522 		error = EINVAL;
523 		goto error_exit;
524 	}
525 
526 	if (pmp->pm_Sectors == 0) {
527 		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
528 		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
529 	} else {
530 		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
531 		pmp->pm_HugeSectors = pmp->pm_Sectors;
532 	}
533 	if (!(pmp->pm_flags & MSDOSFS_LARGEFS)) {
534 		if (pmp->pm_HugeSectors > 0xffffffff /
535 		    (pmp->pm_BytesPerSec / sizeof(struct direntry)) + 1) {
536 			/*
537 			 * We cannot deal currently with this size of disk
538 			 * due to fileid limitations (see msdosfs_getattr and
539 			 * msdosfs_readdir)
540 			 */
541 			error = EINVAL;
542 			vfs_mount_error(mp,
543 			    "Disk too big, try '-o large' mount option");
544 			goto error_exit;
545 		}
546 	}
547 
548 	if (pmp->pm_RootDirEnts == 0) {
549 		if (pmp->pm_Sectors
550 		    || pmp->pm_FATsecs
551 		    || getushort(b710->bpbFSVers)) {
552 			error = EINVAL;
553 			printf("mountmsdosfs(): bad FAT32 filesystem\n");
554 			goto error_exit;
555 		}
556 		pmp->pm_fatmask = FAT32_MASK;
557 		pmp->pm_fatmult = 4;
558 		pmp->pm_fatdiv = 1;
559 		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);
560 		if (getushort(b710->bpbExtFlags) & FATMIRROR)
561 			pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
562 		else
563 			pmp->pm_flags |= MSDOSFS_FATMIRROR;
564 	} else
565 		pmp->pm_flags |= MSDOSFS_FATMIRROR;
566 
567 	/*
568 	 * Check a few values (could do some more):
569 	 * - logical sector size: power of 2, >= block size
570 	 * - sectors per cluster: power of 2, >= 1
571 	 * - number of sectors:   >= 1, <= size of partition
572 	 * - number of FAT sectors: >= 1
573 	 */
574 	if ( (SecPerClust == 0)
575 	  || (SecPerClust & (SecPerClust - 1))
576 	  || (pmp->pm_BytesPerSec < DEV_BSIZE)
577 	  || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
578 	  || (pmp->pm_HugeSectors == 0)
579 	  || (pmp->pm_FATsecs == 0)
580 	) {
581 		error = EINVAL;
582 		goto error_exit;
583 	}
584 
585 	pmp->pm_HugeSectors *= pmp->pm_BlkPerSec;
586 	pmp->pm_HiddenSects *= pmp->pm_BlkPerSec;	/* XXX not used? */
587 	pmp->pm_FATsecs     *= pmp->pm_BlkPerSec;
588 	SecPerClust         *= pmp->pm_BlkPerSec;
589 
590 	pmp->pm_fatblk = pmp->pm_ResSectors * pmp->pm_BlkPerSec;
591 
592 	if (FAT32(pmp)) {
593 		pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
594 		pmp->pm_firstcluster = pmp->pm_fatblk
595 			+ (pmp->pm_FATs * pmp->pm_FATsecs);
596 		pmp->pm_fsinfo = getushort(b710->bpbFSInfo) * pmp->pm_BlkPerSec;
597 	} else {
598 		pmp->pm_rootdirblk = pmp->pm_fatblk +
599 			(pmp->pm_FATs * pmp->pm_FATsecs);
600 		pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
601 				       + DEV_BSIZE - 1)
602 			/ DEV_BSIZE; /* in blocks */
603 		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
604 	}
605 
606 	pmp->pm_maxcluster = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
607 	    SecPerClust + 1;
608 	pmp->pm_fatsize = pmp->pm_FATsecs * DEV_BSIZE;	/* XXX not used? */
609 
610 	if (pmp->pm_fatmask == 0) {
611 		if (pmp->pm_maxcluster
612 		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
613 			/*
614 			 * This will usually be a floppy disk. This size makes
615 			 * sure that one fat entry will not be split across
616 			 * multiple blocks.
617 			 */
618 			pmp->pm_fatmask = FAT12_MASK;
619 			pmp->pm_fatmult = 3;
620 			pmp->pm_fatdiv = 2;
621 		} else {
622 			pmp->pm_fatmask = FAT16_MASK;
623 			pmp->pm_fatmult = 2;
624 			pmp->pm_fatdiv = 1;
625 		}
626 	}
627 
628 	clusters = (pmp->pm_fatsize / pmp->pm_fatmult) * pmp->pm_fatdiv;
629 	if (pmp->pm_maxcluster >= clusters) {
630 		printf("Warning: number of clusters (%ld) exceeds FAT "
631 		    "capacity (%ld)\n", pmp->pm_maxcluster + 1, clusters);
632 		pmp->pm_maxcluster = clusters - 1;
633 	}
634 
635 	if (FAT12(pmp))
636 		pmp->pm_fatblocksize = 3 * 512;
637 	else
638 		pmp->pm_fatblocksize = PAGE_SIZE;
639 	pmp->pm_fatblocksize = roundup(pmp->pm_fatblocksize,
640 	    pmp->pm_BytesPerSec);
641 	pmp->pm_fatblocksec = pmp->pm_fatblocksize / DEV_BSIZE;
642 	pmp->pm_bnshift = ffs(DEV_BSIZE) - 1;
643 
644 	/*
645 	 * Compute mask and shift value for isolating cluster relative byte
646 	 * offsets and cluster numbers from a file offset.
647 	 */
648 	pmp->pm_bpcluster = SecPerClust * DEV_BSIZE;
649 	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
650 	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;
651 
652 	/*
653 	 * Check for valid cluster size
654 	 * must be a power of 2
655 	 */
656 	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
657 		error = EINVAL;
658 		goto error_exit;
659 	}
660 
661 	/*
662 	 * Release the bootsector buffer.
663 	 */
664 	brelse(bp);
665 	bp = NULL;
666 
667 	/*
668 	 * Check the fsinfo sector if we have one.  Silently fix up our
669 	 * in-core copy of fp->fsinxtfree if it is unknown (0xffffffff)
670 	 * or too large.  Ignore fp->fsinfree for now, since we need to
671 	 * read the entire FAT anyway to fill the inuse map.
672 	 */
673 	if (pmp->pm_fsinfo) {
674 		struct fsinfo *fp;
675 
676 		if ((error = bread(devvp, pmp->pm_fsinfo, pmp->pm_BytesPerSec,
677 		    NOCRED, &bp)) != 0)
678 			goto error_exit;
679 		fp = (struct fsinfo *)bp->b_data;
680 		if (!bcmp(fp->fsisig1, "RRaA", 4)
681 		    && !bcmp(fp->fsisig2, "rrAa", 4)
682 		    && !bcmp(fp->fsisig3, "\0\0\125\252", 4)) {
683 			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
684 			if (pmp->pm_nxtfree > pmp->pm_maxcluster)
685 				pmp->pm_nxtfree = CLUST_FIRST;
686 		} else
687 			pmp->pm_fsinfo = 0;
688 		brelse(bp);
689 		bp = NULL;
690 	}
691 
692 	/*
693 	 * Finish initializing pmp->pm_nxtfree (just in case the first few
694 	 * sectors aren't properly reserved in the FAT).  This completes
695 	 * the fixup for fp->fsinxtfree, and fixes up the zero-initialized
696 	 * value if there is no fsinfo.  We will use pmp->pm_nxtfree
697 	 * internally even if there is no fsinfo.
698 	 */
699 	if (pmp->pm_nxtfree < CLUST_FIRST)
700 		pmp->pm_nxtfree = CLUST_FIRST;
701 
702 	/*
703 	 * Allocate memory for the bitmap of allocated clusters, and then
704 	 * fill it in.
705 	 */
706 	pmp->pm_inusemap = malloc(howmany(pmp->pm_maxcluster + 1, N_INUSEBITS)
707 				  * sizeof(*pmp->pm_inusemap),
708 				  M_MSDOSFSFAT, M_WAITOK);
709 
710 	/*
711 	 * fillinusemap() needs pm_devvp.
712 	 */
713 	pmp->pm_devvp = devvp;
714 	pmp->pm_dev = dev;
715 
716 	/*
717 	 * Have the inuse map filled in.
718 	 */
719 	if ((error = fillinusemap(pmp)) != 0)
720 		goto error_exit;
721 
722 	/*
723 	 * If they want fat updates to be synchronous then let them suffer
724 	 * the performance degradation in exchange for the on disk copy of
725 	 * the fat being correct just about all the time.  I suppose this
726 	 * would be a good thing to turn on if the kernel is still flakey.
727 	 */
728 	if (mp->mnt_flag & MNT_SYNCHRONOUS)
729 		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;
730 
731 	/*
732 	 * Finish up.
733 	 */
734 	if (ronly)
735 		pmp->pm_flags |= MSDOSFSMNT_RONLY;
736 	else {
737 		if ((error = markvoldirty(pmp, 1)) != 0) {
738 			(void)markvoldirty(pmp, 0);
739 			goto error_exit;
740 		}
741 		pmp->pm_fmod = 1;
742 	}
743 	mp->mnt_data =  pmp;
744 	mp->mnt_stat.f_fsid.val[0] = dev2udev(dev);
745 	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
746 	MNT_ILOCK(mp);
747 	mp->mnt_flag |= MNT_LOCAL;
748 	MNT_IUNLOCK(mp);
749 
750 	if (pmp->pm_flags & MSDOSFS_LARGEFS)
751 		msdosfs_fileno_init(mp);
752 
753 	return 0;
754 
755 error_exit:
756 	if (bp)
757 		brelse(bp);
758 	if (cp != NULL) {
759 		DROP_GIANT();
760 		g_topology_lock();
761 		g_vfs_close(cp);
762 		g_topology_unlock();
763 		PICKUP_GIANT();
764 	}
765 	if (pmp) {
766 		if (pmp->pm_inusemap)
767 			free(pmp->pm_inusemap, M_MSDOSFSFAT);
768 		free(pmp, M_MSDOSFSMNT);
769 		mp->mnt_data = NULL;
770 	}
771 	dev_rel(dev);
772 	return (error);
773 }
774 
775 /*
776  * Unmount the filesystem described by mp.
777  */
778 static int
779 msdosfs_unmount(struct mount *mp, int mntflags)
780 {
781 	struct msdosfsmount *pmp;
782 	int error, flags;
783 
784 	flags = 0;
785 	if (mntflags & MNT_FORCE)
786 		flags |= FORCECLOSE;
787 	error = vflush(mp, 0, flags, curthread);
788 	if (error && error != ENXIO)
789 		return error;
790 	pmp = VFSTOMSDOSFS(mp);
791 	if ((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0) {
792 		error = markvoldirty(pmp, 0);
793 		if (error && error != ENXIO) {
794 			(void)markvoldirty(pmp, 1);
795 			return (error);
796 		}
797 	}
798 	if (pmp->pm_flags & MSDOSFSMNT_KICONV && msdosfs_iconv) {
799 		if (pmp->pm_w2u)
800 			msdosfs_iconv->close(pmp->pm_w2u);
801 		if (pmp->pm_u2w)
802 			msdosfs_iconv->close(pmp->pm_u2w);
803 		if (pmp->pm_d2u)
804 			msdosfs_iconv->close(pmp->pm_d2u);
805 		if (pmp->pm_u2d)
806 			msdosfs_iconv->close(pmp->pm_u2d);
807 	}
808 
809 #ifdef MSDOSFS_DEBUG
810 	{
811 		struct vnode *vp = pmp->pm_devvp;
812 		struct bufobj *bo;
813 
814 		bo = &vp->v_bufobj;
815 		BO_LOCK(bo);
816 		VI_LOCK(vp);
817 		vn_printf(vp,
818 		    "msdosfs_umount(): just before calling VOP_CLOSE()\n");
819 		printf("freef %p, freeb %p, mount %p\n",
820 		    TAILQ_NEXT(vp, v_freelist), vp->v_freelist.tqe_prev,
821 		    vp->v_mount);
822 		printf("cleanblkhd %p, dirtyblkhd %p, numoutput %ld, type %d\n",
823 		    TAILQ_FIRST(&vp->v_bufobj.bo_clean.bv_hd),
824 		    TAILQ_FIRST(&vp->v_bufobj.bo_dirty.bv_hd),
825 		    vp->v_bufobj.bo_numoutput, vp->v_type);
826 		VI_UNLOCK(vp);
827 		BO_UNLOCK(bo);
828 	}
829 #endif
830 	DROP_GIANT();
831 	g_topology_lock();
832 	g_vfs_close(pmp->pm_cp);
833 	g_topology_unlock();
834 	PICKUP_GIANT();
835 	vrele(pmp->pm_devvp);
836 	dev_rel(pmp->pm_dev);
837 	free(pmp->pm_inusemap, M_MSDOSFSFAT);
838 	if (pmp->pm_flags & MSDOSFS_LARGEFS)
839 		msdosfs_fileno_free(mp);
840 	free(pmp, M_MSDOSFSMNT);
841 	mp->mnt_data = NULL;
842 	MNT_ILOCK(mp);
843 	mp->mnt_flag &= ~MNT_LOCAL;
844 	MNT_IUNLOCK(mp);
845 	return (error);
846 }
847 
848 static int
849 msdosfs_root(struct mount *mp, int flags, struct vnode **vpp)
850 {
851 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
852 	struct denode *ndep;
853 	int error;
854 
855 #ifdef MSDOSFS_DEBUG
856 	printf("msdosfs_root(); mp %p, pmp %p\n", mp, pmp);
857 #endif
858 	error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, &ndep);
859 	if (error)
860 		return (error);
861 	*vpp = DETOV(ndep);
862 	return (0);
863 }
864 
865 static int
866 msdosfs_statfs(struct mount *mp, struct statfs *sbp)
867 {
868 	struct msdosfsmount *pmp;
869 
870 	pmp = VFSTOMSDOSFS(mp);
871 	sbp->f_bsize = pmp->pm_bpcluster;
872 	sbp->f_iosize = pmp->pm_bpcluster;
873 	sbp->f_blocks = pmp->pm_maxcluster + 1;
874 	sbp->f_bfree = pmp->pm_freeclustercount;
875 	sbp->f_bavail = pmp->pm_freeclustercount;
876 	sbp->f_files = pmp->pm_RootDirEnts;	/* XXX */
877 	sbp->f_ffree = 0;	/* what to put in here? */
878 	return (0);
879 }
880 
881 static int
882 msdosfs_sync(struct mount *mp, int waitfor)
883 {
884 	struct vnode *vp, *nvp;
885 	struct thread *td;
886 	struct denode *dep;
887 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
888 	int error, allerror = 0;
889 
890 	td = curthread;
891 
892 	/*
893 	 * If we ever switch to not updating all of the fats all the time,
894 	 * this would be the place to update them from the first one.
895 	 */
896 	if (pmp->pm_fmod != 0) {
897 		if (pmp->pm_flags & MSDOSFSMNT_RONLY)
898 			panic("msdosfs_sync: rofs mod");
899 		else {
900 			/* update fats here */
901 		}
902 	}
903 	/*
904 	 * Write back each (modified) denode.
905 	 */
906 	MNT_ILOCK(mp);
907 loop:
908 	MNT_VNODE_FOREACH(vp, mp, nvp) {
909 		VI_LOCK(vp);
910 		if (vp->v_type == VNON || (vp->v_iflag & VI_DOOMED)) {
911 			VI_UNLOCK(vp);
912 			continue;
913 		}
914 		MNT_IUNLOCK(mp);
915 		dep = VTODE(vp);
916 		if ((dep->de_flag &
917 		    (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0 &&
918 		    (vp->v_bufobj.bo_dirty.bv_cnt == 0 ||
919 		    waitfor == MNT_LAZY)) {
920 			VI_UNLOCK(vp);
921 			MNT_ILOCK(mp);
922 			continue;
923 		}
924 		error = vget(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, td);
925 		if (error) {
926 			MNT_ILOCK(mp);
927 			if (error == ENOENT)
928 				goto loop;
929 			continue;
930 		}
931 		error = VOP_FSYNC(vp, waitfor, td);
932 		if (error)
933 			allerror = error;
934 		VOP_UNLOCK(vp, 0);
935 		vrele(vp);
936 		MNT_ILOCK(mp);
937 	}
938 	MNT_IUNLOCK(mp);
939 
940 	/*
941 	 * Flush filesystem control info.
942 	 */
943 	if (waitfor != MNT_LAZY) {
944 		vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY);
945 		error = VOP_FSYNC(pmp->pm_devvp, waitfor, td);
946 		if (error)
947 			allerror = error;
948 		VOP_UNLOCK(pmp->pm_devvp, 0);
949 	}
950 	return (allerror);
951 }
952 
953 static int
954 msdosfs_fhtovp(struct mount *mp, struct fid *fhp, struct vnode **vpp)
955 {
956 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
957 	struct defid *defhp = (struct defid *) fhp;
958 	struct denode *dep;
959 	int error;
960 
961 	error = deget(pmp, defhp->defid_dirclust, defhp->defid_dirofs, &dep);
962 	if (error) {
963 		*vpp = NULLVP;
964 		return (error);
965 	}
966 	*vpp = DETOV(dep);
967 	vnode_create_vobject(*vpp, dep->de_FileSize, curthread);
968 	return (0);
969 }
970 
971 static struct vfsops msdosfs_vfsops = {
972 	.vfs_fhtovp =		msdosfs_fhtovp,
973 	.vfs_mount =		msdosfs_mount,
974 	.vfs_cmount =		msdosfs_cmount,
975 	.vfs_root =		msdosfs_root,
976 	.vfs_statfs =		msdosfs_statfs,
977 	.vfs_sync =		msdosfs_sync,
978 	.vfs_unmount =		msdosfs_unmount,
979 };
980 
981 VFS_SET(msdosfs_vfsops, msdosfs, 0);
982 MODULE_VERSION(msdosfs, 1);
983