xref: /freebsd/sys/fs/msdosfs/msdosfs_vfsops.c (revision db612abe8df3355d1eb23bb3b50fdd97bc21e979)
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 		    struct thread *td);
108 static vfs_fhtovp_t	msdosfs_fhtovp;
109 static vfs_mount_t	msdosfs_mount;
110 static vfs_root_t	msdosfs_root;
111 static vfs_statfs_t	msdosfs_statfs;
112 static vfs_sync_t	msdosfs_sync;
113 static vfs_unmount_t	msdosfs_unmount;
114 
115 /* Maximum length of a character set name (arbitrary). */
116 #define	MAXCSLEN	64
117 
118 static int
119 update_mp(struct mount *mp, struct thread *td)
120 {
121 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
122 	void *dos, *win, *local;
123 	int error, v;
124 
125 	if (!vfs_getopt(mp->mnt_optnew, "kiconv", NULL, NULL)) {
126 		if (msdosfs_iconv != NULL) {
127 			error = vfs_getopt(mp->mnt_optnew,
128 			    "cs_win", &win, NULL);
129 			if (!error)
130 				error = vfs_getopt(mp->mnt_optnew,
131 				    "cs_local", &local, NULL);
132 			if (!error)
133 				error = vfs_getopt(mp->mnt_optnew,
134 				    "cs_dos", &dos, NULL);
135 			if (!error) {
136 				msdosfs_iconv->open(win, local, &pmp->pm_u2w);
137 				msdosfs_iconv->open(local, win, &pmp->pm_w2u);
138 				msdosfs_iconv->open(dos, local, &pmp->pm_u2d);
139 				msdosfs_iconv->open(local, dos, &pmp->pm_d2u);
140 			}
141 			if (error != 0)
142 				return (error);
143 		} else {
144 			pmp->pm_w2u = NULL;
145 			pmp->pm_u2w = NULL;
146 			pmp->pm_d2u = NULL;
147 			pmp->pm_u2d = NULL;
148 		}
149 	}
150 
151 	if (1 == vfs_scanopt(mp->mnt_optnew, "gid", "%d", &v))
152 		pmp->pm_gid = v;
153 	if (1 == vfs_scanopt(mp->mnt_optnew, "uid", "%d", &v))
154 		pmp->pm_uid = v;
155 	if (1 == vfs_scanopt(mp->mnt_optnew, "mask", "%d", &v))
156 		pmp->pm_mask = v & ALLPERMS;
157 	if (1 == vfs_scanopt(mp->mnt_optnew, "dirmask", "%d", &v))
158 		pmp->pm_dirmask = v & ALLPERMS;
159 	vfs_flagopt(mp->mnt_optnew, "shortname",
160 	    &pmp->pm_flags, MSDOSFSMNT_SHORTNAME);
161 	vfs_flagopt(mp->mnt_optnew, "shortnames",
162 	    &pmp->pm_flags, MSDOSFSMNT_SHORTNAME);
163 	vfs_flagopt(mp->mnt_optnew, "longname",
164 	    &pmp->pm_flags, MSDOSFSMNT_LONGNAME);
165 	vfs_flagopt(mp->mnt_optnew, "longnames",
166 	    &pmp->pm_flags, MSDOSFSMNT_LONGNAME);
167 	vfs_flagopt(mp->mnt_optnew, "kiconv",
168 	    &pmp->pm_flags, MSDOSFSMNT_KICONV);
169 
170 	if (vfs_getopt(mp->mnt_optnew, "nowin95", NULL, NULL) == 0)
171 		pmp->pm_flags |= MSDOSFSMNT_NOWIN95;
172 	else
173 		pmp->pm_flags &= ~MSDOSFSMNT_NOWIN95;
174 
175 	if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
176 		pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
177 	else if (!(pmp->pm_flags &
178 	    (MSDOSFSMNT_SHORTNAME | MSDOSFSMNT_LONGNAME))) {
179 		struct vnode *rootvp;
180 
181 		/*
182 		 * Try to divine whether to support Win'95 long filenames
183 		 */
184 		if (FAT32(pmp))
185 			pmp->pm_flags |= MSDOSFSMNT_LONGNAME;
186 		else {
187 			if ((error =
188 			    msdosfs_root(mp, LK_EXCLUSIVE, &rootvp, td)) != 0)
189 				return error;
190 			pmp->pm_flags |= findwin95(VTODE(rootvp)) ?
191 			    MSDOSFSMNT_LONGNAME : MSDOSFSMNT_SHORTNAME;
192 			vput(rootvp);
193 		}
194 	}
195 	return 0;
196 }
197 
198 static int
199 msdosfs_cmount(struct mntarg *ma, void *data, int flags, struct thread *td)
200 {
201 	struct msdosfs_args args;
202 	int error;
203 
204 	if (data == NULL)
205 		return (EINVAL);
206 	error = copyin(data, &args, sizeof args);
207 	if (error)
208 		return (error);
209 
210 	ma = mount_argsu(ma, "from", args.fspec, MAXPATHLEN);
211 	ma = mount_arg(ma, "export", &args.export, sizeof args.export);
212 	ma = mount_argf(ma, "uid", "%d", args.uid);
213 	ma = mount_argf(ma, "gid", "%d", args.gid);
214 	ma = mount_argf(ma, "mask", "%d", args.mask);
215 	ma = mount_argf(ma, "dirmask", "%d", args.dirmask);
216 
217 	ma = mount_argb(ma, args.flags & MSDOSFSMNT_SHORTNAME, "noshortname");
218 	ma = mount_argb(ma, args.flags & MSDOSFSMNT_LONGNAME, "nolongname");
219 	ma = mount_argb(ma, !(args.flags & MSDOSFSMNT_NOWIN95), "nowin95");
220 	ma = mount_argb(ma, args.flags & MSDOSFSMNT_KICONV, "nokiconv");
221 
222 	ma = mount_argsu(ma, "cs_win", args.cs_win, MAXCSLEN);
223 	ma = mount_argsu(ma, "cs_dos", args.cs_dos, MAXCSLEN);
224 	ma = mount_argsu(ma, "cs_local", args.cs_local, MAXCSLEN);
225 
226 	error = kernel_mount(ma, flags);
227 
228 	return (error);
229 }
230 
231 /*
232  * mp - path - addr in user space of mount point (ie /usr or whatever)
233  * data - addr in user space of mount params including the name of the block
234  * special file to treat as a filesystem.
235  */
236 static int
237 msdosfs_mount(struct mount *mp, struct thread *td)
238 {
239 	struct vnode *devvp;	  /* vnode for blk device to mount */
240 	/* msdosfs specific mount control block */
241 	struct msdosfsmount *pmp = NULL;
242 	struct nameidata ndp;
243 	int error, flags;
244 	mode_t accessmode;
245 	char *from;
246 
247 	if (vfs_filteropt(mp->mnt_optnew, msdosfs_opts))
248 		return (EINVAL);
249 
250 	/*
251 	 * If updating, check whether changing from read-only to
252 	 * read/write; if there is no device name, that's all we do.
253 	 */
254 	if (mp->mnt_flag & MNT_UPDATE) {
255 		pmp = VFSTOMSDOSFS(mp);
256 		if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) {
257 			/*
258 			 * Forbid export requests if filesystem has
259 			 * MSDOSFS_LARGEFS flag set.
260 			 */
261 			if ((pmp->pm_flags & MSDOSFS_LARGEFS) != 0) {
262 				vfs_mount_error(mp,
263 				    "MSDOSFS_LARGEFS flag set, cannot export");
264 				return (EOPNOTSUPP);
265 			}
266 		}
267 		if (!(pmp->pm_flags & MSDOSFSMNT_RONLY) &&
268 		    vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0)) {
269 			error = VFS_SYNC(mp, MNT_WAIT, td);
270 			if (error)
271 				return (error);
272 			flags = WRITECLOSE;
273 			if (mp->mnt_flag & MNT_FORCE)
274 				flags |= FORCECLOSE;
275 			error = vflush(mp, 0, flags, td);
276 			if (error)
277 				return (error);
278 
279 			/*
280 			 * Now the volume is clean.  Mark it so while the
281 			 * device is still rw.
282 			 */
283 			error = markvoldirty(pmp, 0);
284 			if (error) {
285 				(void)markvoldirty(pmp, 1);
286 				return (error);
287 			}
288 
289 			/* Downgrade the device from rw to ro. */
290 			DROP_GIANT();
291 			g_topology_lock();
292 			error = g_access(pmp->pm_cp, 0, -1, 0);
293 			g_topology_unlock();
294 			PICKUP_GIANT();
295 			if (error) {
296 				(void)markvoldirty(pmp, 1);
297 				return (error);
298 			}
299 
300 			/*
301 			 * Backing out after an error was painful in the
302 			 * above.  Now we are committed to succeeding.
303 			 */
304 			pmp->pm_fmod = 0;
305 			pmp->pm_flags |= MSDOSFSMNT_RONLY;
306 			MNT_ILOCK(mp);
307 			mp->mnt_flag |= MNT_RDONLY;
308 			MNT_IUNLOCK(mp);
309 		} else if ((pmp->pm_flags & MSDOSFSMNT_RONLY) &&
310 		    !vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0)) {
311 			/*
312 			 * If upgrade to read-write by non-root, then verify
313 			 * that user has necessary permissions on the device.
314 			 */
315 			devvp = pmp->pm_devvp;
316 			vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
317 			error = VOP_ACCESS(devvp, VREAD | VWRITE,
318 			    td->td_ucred, td);
319 			if (error)
320 				error = priv_check(td, PRIV_VFS_MOUNT_PERM);
321 			if (error) {
322 				VOP_UNLOCK(devvp, 0);
323 				return (error);
324 			}
325 			VOP_UNLOCK(devvp, 0);
326 			DROP_GIANT();
327 			g_topology_lock();
328 			error = g_access(pmp->pm_cp, 0, 1, 0);
329 			g_topology_unlock();
330 			PICKUP_GIANT();
331 			if (error)
332 				return (error);
333 
334 			pmp->pm_fmod = 1;
335 			pmp->pm_flags &= ~MSDOSFSMNT_RONLY;
336 			MNT_ILOCK(mp);
337 			mp->mnt_flag &= ~MNT_RDONLY;
338 			MNT_IUNLOCK(mp);
339 
340 			/* Now that the volume is modifiable, mark it dirty. */
341 			error = markvoldirty(pmp, 1);
342 			if (error)
343 				return (error);
344 		}
345 	}
346 	/*
347 	 * Not an update, or updating the name: look up the name
348 	 * and verify that it refers to a sensible disk device.
349 	 */
350 	if (vfs_getopt(mp->mnt_optnew, "from", (void **)&from, NULL))
351 		return (EINVAL);
352 	NDINIT(&ndp, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, from, td);
353 	error = namei(&ndp);
354 	if (error)
355 		return (error);
356 	devvp = ndp.ni_vp;
357 	NDFREE(&ndp, NDF_ONLY_PNBUF);
358 
359 	if (!vn_isdisk(devvp, &error)) {
360 		vput(devvp);
361 		return (error);
362 	}
363 	/*
364 	 * If mount by non-root, then verify that user has necessary
365 	 * permissions on the device.
366 	 */
367 	accessmode = VREAD;
368 	if ((mp->mnt_flag & MNT_RDONLY) == 0)
369 		accessmode |= VWRITE;
370 	error = VOP_ACCESS(devvp, accessmode, td->td_ucred, td);
371 	if (error)
372 		error = priv_check(td, PRIV_VFS_MOUNT_PERM);
373 	if (error) {
374 		vput(devvp);
375 		return (error);
376 	}
377 	if ((mp->mnt_flag & MNT_UPDATE) == 0) {
378 		error = mountmsdosfs(devvp, mp, td);
379 #ifdef MSDOSFS_DEBUG		/* only needed for the printf below */
380 		pmp = VFSTOMSDOSFS(mp);
381 #endif
382 	} else {
383 		if (devvp != pmp->pm_devvp)
384 			error = EINVAL;	/* XXX needs translation */
385 		else
386 			vput(devvp);
387 	}
388 	if (error) {
389 		vrele(devvp);
390 		return (error);
391 	}
392 
393 	error = update_mp(mp, td);
394 	if (error) {
395 		if ((mp->mnt_flag & MNT_UPDATE) == 0)
396 			msdosfs_unmount(mp, MNT_FORCE, td);
397 		return error;
398 	}
399 
400 	vfs_mountedfrom(mp, from);
401 #ifdef MSDOSFS_DEBUG
402 	printf("msdosfs_mount(): mp %p, pmp %p, inusemap %p\n", mp, pmp, pmp->pm_inusemap);
403 #endif
404 	return (0);
405 }
406 
407 static int
408 mountmsdosfs(struct vnode *devvp, struct mount *mp, struct thread *td)
409 {
410 	struct msdosfsmount *pmp;
411 	struct buf *bp;
412 	struct cdev *dev = devvp->v_rdev;
413 	union bootsector *bsp;
414 	struct byte_bpb33 *b33;
415 	struct byte_bpb50 *b50;
416 	struct byte_bpb710 *b710;
417 	u_int8_t SecPerClust;
418 	u_long clusters;
419 	int ronly, error;
420 	struct g_consumer *cp;
421 	struct bufobj *bo;
422 
423 	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
424 	/* XXX: use VOP_ACCESS to check FS perms */
425 	DROP_GIANT();
426 	g_topology_lock();
427 	error = g_vfs_open(devvp, &cp, "msdosfs", ronly ? 0 : 1);
428 	g_topology_unlock();
429 	PICKUP_GIANT();
430 	VOP_UNLOCK(devvp, 0);
431 	if (error)
432 		return (error);
433 
434 	bo = &devvp->v_bufobj;
435 	bp = NULL;		/* This and pmp both used in error_exit. */
436 	pmp = NULL;
437 
438 	/*
439 	 * Read the boot sector of the filesystem, and then check the
440 	 * boot signature.  If not a dos boot sector then error out.
441 	 *
442 	 * NOTE: 8192 is a magic size that works for ffs.
443 	 */
444 	error = bread(devvp, 0, 8192, NOCRED, &bp);
445 	if (error)
446 		goto error_exit;
447 	bp->b_flags |= B_AGE;
448 	bsp = (union bootsector *)bp->b_data;
449 	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
450 	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
451 	b710 = (struct byte_bpb710 *)bsp->bs710.bsBPB;
452 
453 #ifndef MSDOSFS_NOCHECKSIG
454 	if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
455 	    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
456 		error = EINVAL;
457 		goto error_exit;
458 	}
459 #endif
460 
461 	pmp = malloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK | M_ZERO);
462 	pmp->pm_mountp = mp;
463 	pmp->pm_cp = cp;
464 	pmp->pm_bo = bo;
465 
466 	/*
467 	 * Initialize ownerships and permissions, since nothing else will
468 	 * initialize them iff we are mounting root.
469 	 */
470 	pmp->pm_uid = UID_ROOT;
471 	pmp->pm_gid = GID_WHEEL;
472 	pmp->pm_mask = pmp->pm_dirmask = S_IXUSR | S_IXGRP | S_IXOTH |
473 	    S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR;
474 
475 	/*
476 	 * Experimental support for large MS-DOS filesystems.
477 	 * WARNING: This uses at least 32 bytes of kernel memory (which is not
478 	 * reclaimed until the FS is unmounted) for each file on disk to map
479 	 * between the 32-bit inode numbers used by VFS and the 64-bit
480 	 * pseudo-inode numbers used internally by msdosfs. This is only
481 	 * safe to use in certain controlled situations (e.g. read-only FS
482 	 * with less than 1 million files).
483 	 * Since the mappings do not persist across unmounts (or reboots), these
484 	 * filesystems are not suitable for exporting through NFS, or any other
485 	 * application that requires fixed inode numbers.
486 	 */
487 	vfs_flagopt(mp->mnt_optnew, "large", &pmp->pm_flags, MSDOSFS_LARGEFS);
488 
489 	/*
490 	 * Compute several useful quantities from the bpb in the
491 	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
492 	 * the fields that are different between dos 5 and dos 3.3.
493 	 */
494 	SecPerClust = b50->bpbSecPerClust;
495 	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
496 	if (pmp->pm_BytesPerSec < DEV_BSIZE) {
497 		error = EINVAL;
498 		goto error_exit;
499 	}
500 	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
501 	pmp->pm_FATs = b50->bpbFATs;
502 	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
503 	pmp->pm_Sectors = getushort(b50->bpbSectors);
504 	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
505 	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
506 	pmp->pm_Heads = getushort(b50->bpbHeads);
507 	pmp->pm_Media = b50->bpbMedia;
508 
509 	/* calculate the ratio of sector size to DEV_BSIZE */
510 	pmp->pm_BlkPerSec = pmp->pm_BytesPerSec / DEV_BSIZE;
511 
512 	/*
513 	 * We don't check pm_Heads nor pm_SecPerTrack, because
514 	 * these may not be set for EFI file systems. We don't
515 	 * use these anyway, so we're unaffected if they are
516 	 * invalid.
517 	 */
518 	if (!pmp->pm_BytesPerSec || !SecPerClust) {
519 		error = EINVAL;
520 		goto error_exit;
521 	}
522 
523 	if (pmp->pm_Sectors == 0) {
524 		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
525 		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
526 	} else {
527 		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
528 		pmp->pm_HugeSectors = pmp->pm_Sectors;
529 	}
530 	if (!(pmp->pm_flags & MSDOSFS_LARGEFS)) {
531 		if (pmp->pm_HugeSectors > 0xffffffff /
532 		    (pmp->pm_BytesPerSec / sizeof(struct direntry)) + 1) {
533 			/*
534 			 * We cannot deal currently with this size of disk
535 			 * due to fileid limitations (see msdosfs_getattr and
536 			 * msdosfs_readdir)
537 			 */
538 			error = EINVAL;
539 			vfs_mount_error(mp,
540 			    "Disk too big, try '-o large' mount option");
541 			goto error_exit;
542 		}
543 	}
544 
545 	if (pmp->pm_RootDirEnts == 0) {
546 		if (pmp->pm_Sectors
547 		    || pmp->pm_FATsecs
548 		    || getushort(b710->bpbFSVers)) {
549 			error = EINVAL;
550 			printf("mountmsdosfs(): bad FAT32 filesystem\n");
551 			goto error_exit;
552 		}
553 		pmp->pm_fatmask = FAT32_MASK;
554 		pmp->pm_fatmult = 4;
555 		pmp->pm_fatdiv = 1;
556 		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);
557 		if (getushort(b710->bpbExtFlags) & FATMIRROR)
558 			pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
559 		else
560 			pmp->pm_flags |= MSDOSFS_FATMIRROR;
561 	} else
562 		pmp->pm_flags |= MSDOSFS_FATMIRROR;
563 
564 	/*
565 	 * Check a few values (could do some more):
566 	 * - logical sector size: power of 2, >= block size
567 	 * - sectors per cluster: power of 2, >= 1
568 	 * - number of sectors:   >= 1, <= size of partition
569 	 * - number of FAT sectors: >= 1
570 	 */
571 	if ( (SecPerClust == 0)
572 	  || (SecPerClust & (SecPerClust - 1))
573 	  || (pmp->pm_BytesPerSec < DEV_BSIZE)
574 	  || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
575 	  || (pmp->pm_HugeSectors == 0)
576 	  || (pmp->pm_FATsecs == 0)
577 	) {
578 		error = EINVAL;
579 		goto error_exit;
580 	}
581 
582 	pmp->pm_HugeSectors *= pmp->pm_BlkPerSec;
583 	pmp->pm_HiddenSects *= pmp->pm_BlkPerSec;	/* XXX not used? */
584 	pmp->pm_FATsecs     *= pmp->pm_BlkPerSec;
585 	SecPerClust         *= pmp->pm_BlkPerSec;
586 
587 	pmp->pm_fatblk = pmp->pm_ResSectors * pmp->pm_BlkPerSec;
588 
589 	if (FAT32(pmp)) {
590 		pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
591 		pmp->pm_firstcluster = pmp->pm_fatblk
592 			+ (pmp->pm_FATs * pmp->pm_FATsecs);
593 		pmp->pm_fsinfo = getushort(b710->bpbFSInfo) * pmp->pm_BlkPerSec;
594 	} else {
595 		pmp->pm_rootdirblk = pmp->pm_fatblk +
596 			(pmp->pm_FATs * pmp->pm_FATsecs);
597 		pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
598 				       + DEV_BSIZE - 1)
599 			/ DEV_BSIZE; /* in blocks */
600 		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
601 	}
602 
603 	pmp->pm_maxcluster = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
604 	    SecPerClust + 1;
605 	pmp->pm_fatsize = pmp->pm_FATsecs * DEV_BSIZE;	/* XXX not used? */
606 
607 	if (pmp->pm_fatmask == 0) {
608 		if (pmp->pm_maxcluster
609 		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
610 			/*
611 			 * This will usually be a floppy disk. This size makes
612 			 * sure that one fat entry will not be split across
613 			 * multiple blocks.
614 			 */
615 			pmp->pm_fatmask = FAT12_MASK;
616 			pmp->pm_fatmult = 3;
617 			pmp->pm_fatdiv = 2;
618 		} else {
619 			pmp->pm_fatmask = FAT16_MASK;
620 			pmp->pm_fatmult = 2;
621 			pmp->pm_fatdiv = 1;
622 		}
623 	}
624 
625 	clusters = (pmp->pm_fatsize / pmp->pm_fatmult) * pmp->pm_fatdiv;
626 	if (pmp->pm_maxcluster >= clusters) {
627 		printf("Warning: number of clusters (%ld) exceeds FAT "
628 		    "capacity (%ld)\n", pmp->pm_maxcluster + 1, clusters);
629 		pmp->pm_maxcluster = clusters - 1;
630 	}
631 
632 	if (FAT12(pmp))
633 		pmp->pm_fatblocksize = 3 * 512;
634 	else
635 		pmp->pm_fatblocksize = PAGE_SIZE;
636 	pmp->pm_fatblocksize = roundup(pmp->pm_fatblocksize,
637 	    pmp->pm_BytesPerSec);
638 	pmp->pm_fatblocksec = pmp->pm_fatblocksize / DEV_BSIZE;
639 	pmp->pm_bnshift = ffs(DEV_BSIZE) - 1;
640 
641 	/*
642 	 * Compute mask and shift value for isolating cluster relative byte
643 	 * offsets and cluster numbers from a file offset.
644 	 */
645 	pmp->pm_bpcluster = SecPerClust * DEV_BSIZE;
646 	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
647 	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;
648 
649 	/*
650 	 * Check for valid cluster size
651 	 * must be a power of 2
652 	 */
653 	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
654 		error = EINVAL;
655 		goto error_exit;
656 	}
657 
658 	/*
659 	 * Release the bootsector buffer.
660 	 */
661 	brelse(bp);
662 	bp = NULL;
663 
664 	/*
665 	 * Check the fsinfo sector if we have one.  Silently fix up our
666 	 * in-core copy of fp->fsinxtfree if it is unknown (0xffffffff)
667 	 * or too large.  Ignore fp->fsinfree for now, since we need to
668 	 * read the entire FAT anyway to fill the inuse map.
669 	 */
670 	if (pmp->pm_fsinfo) {
671 		struct fsinfo *fp;
672 
673 		if ((error = bread(devvp, pmp->pm_fsinfo, pmp->pm_BytesPerSec,
674 		    NOCRED, &bp)) != 0)
675 			goto error_exit;
676 		fp = (struct fsinfo *)bp->b_data;
677 		if (!bcmp(fp->fsisig1, "RRaA", 4)
678 		    && !bcmp(fp->fsisig2, "rrAa", 4)
679 		    && !bcmp(fp->fsisig3, "\0\0\125\252", 4)) {
680 			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
681 			if (pmp->pm_nxtfree > pmp->pm_maxcluster)
682 				pmp->pm_nxtfree = CLUST_FIRST;
683 		} else
684 			pmp->pm_fsinfo = 0;
685 		brelse(bp);
686 		bp = NULL;
687 	}
688 
689 	/*
690 	 * Finish initializing pmp->pm_nxtfree (just in case the first few
691 	 * sectors aren't properly reserved in the FAT).  This completes
692 	 * the fixup for fp->fsinxtfree, and fixes up the zero-initialized
693 	 * value if there is no fsinfo.  We will use pmp->pm_nxtfree
694 	 * internally even if there is no fsinfo.
695 	 */
696 	if (pmp->pm_nxtfree < CLUST_FIRST)
697 		pmp->pm_nxtfree = CLUST_FIRST;
698 
699 	/*
700 	 * Allocate memory for the bitmap of allocated clusters, and then
701 	 * fill it in.
702 	 */
703 	pmp->pm_inusemap = malloc(howmany(pmp->pm_maxcluster + 1, N_INUSEBITS)
704 				  * sizeof(*pmp->pm_inusemap),
705 				  M_MSDOSFSFAT, M_WAITOK);
706 
707 	/*
708 	 * fillinusemap() needs pm_devvp.
709 	 */
710 	pmp->pm_devvp = devvp;
711 
712 	/*
713 	 * Have the inuse map filled in.
714 	 */
715 	if ((error = fillinusemap(pmp)) != 0)
716 		goto error_exit;
717 
718 	/*
719 	 * If they want fat updates to be synchronous then let them suffer
720 	 * the performance degradation in exchange for the on disk copy of
721 	 * the fat being correct just about all the time.  I suppose this
722 	 * would be a good thing to turn on if the kernel is still flakey.
723 	 */
724 	if (mp->mnt_flag & MNT_SYNCHRONOUS)
725 		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;
726 
727 	/*
728 	 * Finish up.
729 	 */
730 	if (ronly)
731 		pmp->pm_flags |= MSDOSFSMNT_RONLY;
732 	else {
733 		if ((error = markvoldirty(pmp, 1)) != 0) {
734 			(void)markvoldirty(pmp, 0);
735 			goto error_exit;
736 		}
737 		pmp->pm_fmod = 1;
738 	}
739 	mp->mnt_data =  pmp;
740 	mp->mnt_stat.f_fsid.val[0] = dev2udev(dev);
741 	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
742 	MNT_ILOCK(mp);
743 	mp->mnt_flag |= MNT_LOCAL;
744 	MNT_IUNLOCK(mp);
745 
746 	if (pmp->pm_flags & MSDOSFS_LARGEFS)
747 		msdosfs_fileno_init(mp);
748 
749 	return 0;
750 
751 error_exit:
752 	if (bp)
753 		brelse(bp);
754 	if (cp != NULL) {
755 		DROP_GIANT();
756 		g_topology_lock();
757 		g_vfs_close(cp, td);
758 		g_topology_unlock();
759 		PICKUP_GIANT();
760 	}
761 	if (pmp) {
762 		if (pmp->pm_inusemap)
763 			free(pmp->pm_inusemap, M_MSDOSFSFAT);
764 		free(pmp, M_MSDOSFSMNT);
765 		mp->mnt_data = NULL;
766 	}
767 	return (error);
768 }
769 
770 /*
771  * Unmount the filesystem described by mp.
772  */
773 static int
774 msdosfs_unmount(struct mount *mp, int mntflags, struct thread *td)
775 {
776 	struct msdosfsmount *pmp;
777 	int error, flags;
778 
779 	flags = 0;
780 	if (mntflags & MNT_FORCE)
781 		flags |= FORCECLOSE;
782 	error = vflush(mp, 0, flags, td);
783 	if (error)
784 		return error;
785 	pmp = VFSTOMSDOSFS(mp);
786 	if ((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0) {
787 		error = markvoldirty(pmp, 0);
788 		if (error) {
789 			(void)markvoldirty(pmp, 1);
790 			return (error);
791 		}
792 	}
793 	if (pmp->pm_flags & MSDOSFSMNT_KICONV && msdosfs_iconv) {
794 		if (pmp->pm_w2u)
795 			msdosfs_iconv->close(pmp->pm_w2u);
796 		if (pmp->pm_u2w)
797 			msdosfs_iconv->close(pmp->pm_u2w);
798 		if (pmp->pm_d2u)
799 			msdosfs_iconv->close(pmp->pm_d2u);
800 		if (pmp->pm_u2d)
801 			msdosfs_iconv->close(pmp->pm_u2d);
802 	}
803 
804 #ifdef MSDOSFS_DEBUG
805 	{
806 		struct vnode *vp = pmp->pm_devvp;
807 		struct bufobj *bo;
808 
809 		bo = &vp->v_bufobj;
810 		BO_LOCK(bo);
811 		VI_LOCK(vp);
812 		vn_printf(vp,
813 		    "msdosfs_umount(): just before calling VOP_CLOSE()\n");
814 		printf("freef %p, freeb %p, mount %p\n",
815 		    TAILQ_NEXT(vp, v_freelist), vp->v_freelist.tqe_prev,
816 		    vp->v_mount);
817 		printf("cleanblkhd %p, dirtyblkhd %p, numoutput %ld, type %d\n",
818 		    TAILQ_FIRST(&vp->v_bufobj.bo_clean.bv_hd),
819 		    TAILQ_FIRST(&vp->v_bufobj.bo_dirty.bv_hd),
820 		    vp->v_bufobj.bo_numoutput, vp->v_type);
821 		VI_UNLOCK(vp);
822 		BO_UNLOCK(bo);
823 	}
824 #endif
825 	DROP_GIANT();
826 	g_topology_lock();
827 	g_vfs_close(pmp->pm_cp, td);
828 	g_topology_unlock();
829 	PICKUP_GIANT();
830 	vrele(pmp->pm_devvp);
831 	free(pmp->pm_inusemap, M_MSDOSFSFAT);
832 	if (pmp->pm_flags & MSDOSFS_LARGEFS)
833 		msdosfs_fileno_free(mp);
834 	free(pmp, M_MSDOSFSMNT);
835 	mp->mnt_data = NULL;
836 	MNT_ILOCK(mp);
837 	mp->mnt_flag &= ~MNT_LOCAL;
838 	MNT_IUNLOCK(mp);
839 	return (0);
840 }
841 
842 static int
843 msdosfs_root(struct mount *mp, int flags, struct vnode **vpp, struct thread *td)
844 {
845 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
846 	struct denode *ndep;
847 	int error;
848 
849 #ifdef MSDOSFS_DEBUG
850 	printf("msdosfs_root(); mp %p, pmp %p\n", mp, pmp);
851 #endif
852 	error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, &ndep);
853 	if (error)
854 		return (error);
855 	*vpp = DETOV(ndep);
856 	return (0);
857 }
858 
859 static int
860 msdosfs_statfs(struct mount *mp, struct statfs *sbp, struct thread *td)
861 {
862 	struct msdosfsmount *pmp;
863 
864 	pmp = VFSTOMSDOSFS(mp);
865 	sbp->f_bsize = pmp->pm_bpcluster;
866 	sbp->f_iosize = pmp->pm_bpcluster;
867 	sbp->f_blocks = pmp->pm_maxcluster + 1;
868 	sbp->f_bfree = pmp->pm_freeclustercount;
869 	sbp->f_bavail = pmp->pm_freeclustercount;
870 	sbp->f_files = pmp->pm_RootDirEnts;	/* XXX */
871 	sbp->f_ffree = 0;	/* what to put in here? */
872 	return (0);
873 }
874 
875 static int
876 msdosfs_sync(struct mount *mp, int waitfor, struct thread *td)
877 {
878 	struct vnode *vp, *nvp;
879 	struct denode *dep;
880 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
881 	int error, allerror = 0;
882 
883 	/*
884 	 * If we ever switch to not updating all of the fats all the time,
885 	 * this would be the place to update them from the first one.
886 	 */
887 	if (pmp->pm_fmod != 0) {
888 		if (pmp->pm_flags & MSDOSFSMNT_RONLY)
889 			panic("msdosfs_sync: rofs mod");
890 		else {
891 			/* update fats here */
892 		}
893 	}
894 	/*
895 	 * Write back each (modified) denode.
896 	 */
897 	MNT_ILOCK(mp);
898 loop:
899 	MNT_VNODE_FOREACH(vp, mp, nvp) {
900 		VI_LOCK(vp);
901 		if (vp->v_type == VNON || (vp->v_iflag & VI_DOOMED)) {
902 			VI_UNLOCK(vp);
903 			continue;
904 		}
905 		MNT_IUNLOCK(mp);
906 		dep = VTODE(vp);
907 		if ((dep->de_flag &
908 		    (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0 &&
909 		    (vp->v_bufobj.bo_dirty.bv_cnt == 0 ||
910 		    waitfor == MNT_LAZY)) {
911 			VI_UNLOCK(vp);
912 			MNT_ILOCK(mp);
913 			continue;
914 		}
915 		error = vget(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, td);
916 		if (error) {
917 			MNT_ILOCK(mp);
918 			if (error == ENOENT)
919 				goto loop;
920 			continue;
921 		}
922 		error = VOP_FSYNC(vp, waitfor, td);
923 		if (error)
924 			allerror = error;
925 		VOP_UNLOCK(vp, 0);
926 		vrele(vp);
927 		MNT_ILOCK(mp);
928 	}
929 	MNT_IUNLOCK(mp);
930 
931 	/*
932 	 * Flush filesystem control info.
933 	 */
934 	if (waitfor != MNT_LAZY) {
935 		vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY);
936 		error = VOP_FSYNC(pmp->pm_devvp, waitfor, td);
937 		if (error)
938 			allerror = error;
939 		VOP_UNLOCK(pmp->pm_devvp, 0);
940 	}
941 	return (allerror);
942 }
943 
944 static int
945 msdosfs_fhtovp(struct mount *mp, struct fid *fhp, struct vnode **vpp)
946 {
947 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
948 	struct defid *defhp = (struct defid *) fhp;
949 	struct denode *dep;
950 	int error;
951 
952 	error = deget(pmp, defhp->defid_dirclust, defhp->defid_dirofs, &dep);
953 	if (error) {
954 		*vpp = NULLVP;
955 		return (error);
956 	}
957 	*vpp = DETOV(dep);
958 	vnode_create_vobject(*vpp, dep->de_FileSize, curthread);
959 	return (0);
960 }
961 
962 static struct vfsops msdosfs_vfsops = {
963 	.vfs_fhtovp =		msdosfs_fhtovp,
964 	.vfs_mount =		msdosfs_mount,
965 	.vfs_cmount =		msdosfs_cmount,
966 	.vfs_root =		msdosfs_root,
967 	.vfs_statfs =		msdosfs_statfs,
968 	.vfs_sync =		msdosfs_sync,
969 	.vfs_unmount =		msdosfs_unmount,
970 };
971 
972 VFS_SET(msdosfs_vfsops, msdosfs, 0);
973 MODULE_VERSION(msdosfs, 1);
974