xref: /freebsd/sys/fs/msdosfs/msdosfs_vfsops.c (revision aa64588d28258aef88cc33b8043112e8856948d0)
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 static const char msdosfs_lock_msg[] = "fatlk";
79 
80 /* Mount options that we support. */
81 static const char *msdosfs_opts[] = {
82 	"async", "noatime", "noclusterr", "noclusterw",
83 	"export", "force", "from", "sync",
84 	"cs_dos", "cs_local", "cs_win", "dirmask",
85 	"gid", "kiconv", "large", "longname",
86 	"longnames", "mask", "shortname", "shortnames",
87 	"uid", "win95", "nowin95",
88 	NULL
89 };
90 
91 #if 1 /*def PC98*/
92 /*
93  * XXX - The boot signature formatted by NEC PC-98 DOS looks like a
94  *       garbage or a random value :-{
95  *       If you want to use that broken-signatured media, define the
96  *       following symbol even though PC/AT.
97  *       (ex. mount PC-98 DOS formatted FD on PC/AT)
98  */
99 #define	MSDOSFS_NOCHECKSIG
100 #endif
101 
102 MALLOC_DEFINE(M_MSDOSFSMNT, "msdosfs_mount", "MSDOSFS mount structure");
103 static MALLOC_DEFINE(M_MSDOSFSFAT, "msdosfs_fat", "MSDOSFS file allocation table");
104 
105 struct iconv_functions *msdosfs_iconv;
106 
107 static int	update_mp(struct mount *mp, struct thread *td);
108 static int	mountmsdosfs(struct vnode *devvp, struct mount *mp);
109 static vfs_fhtovp_t	msdosfs_fhtovp;
110 static vfs_mount_t	msdosfs_mount;
111 static vfs_root_t	msdosfs_root;
112 static vfs_statfs_t	msdosfs_statfs;
113 static vfs_sync_t	msdosfs_sync;
114 static vfs_unmount_t	msdosfs_unmount;
115 
116 /* Maximum length of a character set name (arbitrary). */
117 #define	MAXCSLEN	64
118 
119 static int
120 update_mp(struct mount *mp, struct thread *td)
121 {
122 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
123 	void *dos, *win, *local;
124 	int error, v;
125 
126 	if (!vfs_getopt(mp->mnt_optnew, "kiconv", NULL, NULL)) {
127 		if (msdosfs_iconv != NULL) {
128 			error = vfs_getopt(mp->mnt_optnew,
129 			    "cs_win", &win, NULL);
130 			if (!error)
131 				error = vfs_getopt(mp->mnt_optnew,
132 				    "cs_local", &local, NULL);
133 			if (!error)
134 				error = vfs_getopt(mp->mnt_optnew,
135 				    "cs_dos", &dos, NULL);
136 			if (!error) {
137 				msdosfs_iconv->open(win, local, &pmp->pm_u2w);
138 				msdosfs_iconv->open(local, win, &pmp->pm_w2u);
139 				msdosfs_iconv->open(dos, local, &pmp->pm_u2d);
140 				msdosfs_iconv->open(local, dos, &pmp->pm_d2u);
141 			}
142 			if (error != 0)
143 				return (error);
144 		} else {
145 			pmp->pm_w2u = NULL;
146 			pmp->pm_u2w = NULL;
147 			pmp->pm_d2u = NULL;
148 			pmp->pm_u2d = NULL;
149 		}
150 	}
151 
152 	if (1 == vfs_scanopt(mp->mnt_optnew, "gid", "%d", &v))
153 		pmp->pm_gid = v;
154 	if (1 == vfs_scanopt(mp->mnt_optnew, "uid", "%d", &v))
155 		pmp->pm_uid = v;
156 	if (1 == vfs_scanopt(mp->mnt_optnew, "mask", "%d", &v))
157 		pmp->pm_mask = v & ALLPERMS;
158 	if (1 == vfs_scanopt(mp->mnt_optnew, "dirmask", "%d", &v))
159 		pmp->pm_dirmask = v & ALLPERMS;
160 	vfs_flagopt(mp->mnt_optnew, "shortname",
161 	    &pmp->pm_flags, MSDOSFSMNT_SHORTNAME);
162 	vfs_flagopt(mp->mnt_optnew, "shortnames",
163 	    &pmp->pm_flags, MSDOSFSMNT_SHORTNAME);
164 	vfs_flagopt(mp->mnt_optnew, "longname",
165 	    &pmp->pm_flags, MSDOSFSMNT_LONGNAME);
166 	vfs_flagopt(mp->mnt_optnew, "longnames",
167 	    &pmp->pm_flags, MSDOSFSMNT_LONGNAME);
168 	vfs_flagopt(mp->mnt_optnew, "kiconv",
169 	    &pmp->pm_flags, MSDOSFSMNT_KICONV);
170 
171 	if (vfs_getopt(mp->mnt_optnew, "nowin95", NULL, NULL) == 0)
172 		pmp->pm_flags |= MSDOSFSMNT_NOWIN95;
173 	else
174 		pmp->pm_flags &= ~MSDOSFSMNT_NOWIN95;
175 
176 	if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
177 		pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
178 	else if (!(pmp->pm_flags &
179 	    (MSDOSFSMNT_SHORTNAME | MSDOSFSMNT_LONGNAME))) {
180 		struct vnode *rootvp;
181 
182 		/*
183 		 * Try to divine whether to support Win'95 long filenames
184 		 */
185 		if (FAT32(pmp))
186 			pmp->pm_flags |= MSDOSFSMNT_LONGNAME;
187 		else {
188 			if ((error =
189 			    msdosfs_root(mp, LK_EXCLUSIVE, &rootvp)) != 0)
190 				return error;
191 			pmp->pm_flags |= findwin95(VTODE(rootvp)) ?
192 			    MSDOSFSMNT_LONGNAME : MSDOSFSMNT_SHORTNAME;
193 			vput(rootvp);
194 		}
195 	}
196 	return 0;
197 }
198 
199 static int
200 msdosfs_cmount(struct mntarg *ma, void *data, int flags)
201 {
202 	struct msdosfs_args args;
203 	int error;
204 
205 	if (data == NULL)
206 		return (EINVAL);
207 	error = copyin(data, &args, sizeof args);
208 	if (error)
209 		return (error);
210 
211 	ma = mount_argsu(ma, "from", args.fspec, MAXPATHLEN);
212 	ma = mount_arg(ma, "export", &args.export, sizeof args.export);
213 	ma = mount_argf(ma, "uid", "%d", args.uid);
214 	ma = mount_argf(ma, "gid", "%d", args.gid);
215 	ma = mount_argf(ma, "mask", "%d", args.mask);
216 	ma = mount_argf(ma, "dirmask", "%d", args.dirmask);
217 
218 	ma = mount_argb(ma, args.flags & MSDOSFSMNT_SHORTNAME, "noshortname");
219 	ma = mount_argb(ma, args.flags & MSDOSFSMNT_LONGNAME, "nolongname");
220 	ma = mount_argb(ma, !(args.flags & MSDOSFSMNT_NOWIN95), "nowin95");
221 	ma = mount_argb(ma, args.flags & MSDOSFSMNT_KICONV, "nokiconv");
222 
223 	ma = mount_argsu(ma, "cs_win", args.cs_win, MAXCSLEN);
224 	ma = mount_argsu(ma, "cs_dos", args.cs_dos, MAXCSLEN);
225 	ma = mount_argsu(ma, "cs_local", args.cs_local, MAXCSLEN);
226 
227 	error = kernel_mount(ma, flags);
228 
229 	return (error);
230 }
231 
232 /*
233  * mp - path - addr in user space of mount point (ie /usr or whatever)
234  * data - addr in user space of mount params including the name of the block
235  * special file to treat as a filesystem.
236  */
237 static int
238 msdosfs_mount(struct mount *mp)
239 {
240 	struct vnode *devvp;	  /* vnode for blk device to mount */
241 	struct thread *td;
242 	/* msdosfs specific mount control block */
243 	struct msdosfsmount *pmp = NULL;
244 	struct nameidata ndp;
245 	int error, flags;
246 	accmode_t accmode;
247 	char *from;
248 
249 	td = curthread;
250 	if (vfs_filteropt(mp->mnt_optnew, msdosfs_opts))
251 		return (EINVAL);
252 
253 	/*
254 	 * If updating, check whether changing from read-only to
255 	 * read/write; if there is no device name, that's all we do.
256 	 */
257 	if (mp->mnt_flag & MNT_UPDATE) {
258 		pmp = VFSTOMSDOSFS(mp);
259 		if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) {
260 			/*
261 			 * Forbid export requests if filesystem has
262 			 * MSDOSFS_LARGEFS flag set.
263 			 */
264 			if ((pmp->pm_flags & MSDOSFS_LARGEFS) != 0) {
265 				vfs_mount_error(mp,
266 				    "MSDOSFS_LARGEFS flag set, cannot export");
267 				return (EOPNOTSUPP);
268 			}
269 		}
270 		if (!(pmp->pm_flags & MSDOSFSMNT_RONLY) &&
271 		    vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0)) {
272 			error = VFS_SYNC(mp, MNT_WAIT);
273 			if (error)
274 				return (error);
275 			flags = WRITECLOSE;
276 			if (mp->mnt_flag & MNT_FORCE)
277 				flags |= FORCECLOSE;
278 			error = vflush(mp, 0, flags, td);
279 			if (error)
280 				return (error);
281 
282 			/*
283 			 * Now the volume is clean.  Mark it so while the
284 			 * device is still rw.
285 			 */
286 			error = markvoldirty(pmp, 0);
287 			if (error) {
288 				(void)markvoldirty(pmp, 1);
289 				return (error);
290 			}
291 
292 			/* Downgrade the device from rw to ro. */
293 			DROP_GIANT();
294 			g_topology_lock();
295 			error = g_access(pmp->pm_cp, 0, -1, 0);
296 			g_topology_unlock();
297 			PICKUP_GIANT();
298 			if (error) {
299 				(void)markvoldirty(pmp, 1);
300 				return (error);
301 			}
302 
303 			/*
304 			 * Backing out after an error was painful in the
305 			 * above.  Now we are committed to succeeding.
306 			 */
307 			pmp->pm_fmod = 0;
308 			pmp->pm_flags |= MSDOSFSMNT_RONLY;
309 			MNT_ILOCK(mp);
310 			mp->mnt_flag |= MNT_RDONLY;
311 			MNT_IUNLOCK(mp);
312 		} else if ((pmp->pm_flags & MSDOSFSMNT_RONLY) &&
313 		    !vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0)) {
314 			/*
315 			 * If upgrade to read-write by non-root, then verify
316 			 * that user has necessary permissions on the device.
317 			 */
318 			devvp = pmp->pm_devvp;
319 			vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
320 			error = VOP_ACCESS(devvp, VREAD | VWRITE,
321 			    td->td_ucred, td);
322 			if (error)
323 				error = priv_check(td, PRIV_VFS_MOUNT_PERM);
324 			if (error) {
325 				VOP_UNLOCK(devvp, 0);
326 				return (error);
327 			}
328 			VOP_UNLOCK(devvp, 0);
329 			DROP_GIANT();
330 			g_topology_lock();
331 			error = g_access(pmp->pm_cp, 0, 1, 0);
332 			g_topology_unlock();
333 			PICKUP_GIANT();
334 			if (error)
335 				return (error);
336 
337 			pmp->pm_fmod = 1;
338 			pmp->pm_flags &= ~MSDOSFSMNT_RONLY;
339 			MNT_ILOCK(mp);
340 			mp->mnt_flag &= ~MNT_RDONLY;
341 			MNT_IUNLOCK(mp);
342 
343 			/* Now that the volume is modifiable, mark it dirty. */
344 			error = markvoldirty(pmp, 1);
345 			if (error)
346 				return (error);
347 		}
348 	}
349 	/*
350 	 * Not an update, or updating the name: look up the name
351 	 * and verify that it refers to a sensible disk device.
352 	 */
353 	if (vfs_getopt(mp->mnt_optnew, "from", (void **)&from, NULL))
354 		return (EINVAL);
355 	NDINIT(&ndp, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, from, td);
356 	error = namei(&ndp);
357 	if (error)
358 		return (error);
359 	devvp = ndp.ni_vp;
360 	NDFREE(&ndp, NDF_ONLY_PNBUF);
361 
362 	if (!vn_isdisk(devvp, &error)) {
363 		vput(devvp);
364 		return (error);
365 	}
366 	/*
367 	 * If mount by non-root, then verify that user has necessary
368 	 * permissions on the device.
369 	 */
370 	accmode = VREAD;
371 	if ((mp->mnt_flag & MNT_RDONLY) == 0)
372 		accmode |= VWRITE;
373 	error = VOP_ACCESS(devvp, accmode, td->td_ucred, td);
374 	if (error)
375 		error = priv_check(td, PRIV_VFS_MOUNT_PERM);
376 	if (error) {
377 		vput(devvp);
378 		return (error);
379 	}
380 	if ((mp->mnt_flag & MNT_UPDATE) == 0) {
381 		error = mountmsdosfs(devvp, mp);
382 #ifdef MSDOSFS_DEBUG		/* only needed for the printf below */
383 		pmp = VFSTOMSDOSFS(mp);
384 #endif
385 	} else {
386 		vput(devvp);
387 		if (devvp != pmp->pm_devvp)
388 			return (EINVAL);	/* XXX needs translation */
389 	}
390 	if (error) {
391 		vrele(devvp);
392 		return (error);
393 	}
394 
395 	error = update_mp(mp, td);
396 	if (error) {
397 		if ((mp->mnt_flag & MNT_UPDATE) == 0)
398 			msdosfs_unmount(mp, MNT_FORCE);
399 		return error;
400 	}
401 
402 	vfs_mountedfrom(mp, from);
403 #ifdef MSDOSFS_DEBUG
404 	printf("msdosfs_mount(): mp %p, pmp %p, inusemap %p\n", mp, pmp, pmp->pm_inusemap);
405 #endif
406 	return (0);
407 }
408 
409 static int
410 mountmsdosfs(struct vnode *devvp, struct mount *mp)
411 {
412 	struct msdosfsmount *pmp;
413 	struct buf *bp;
414 	struct cdev *dev;
415 	union bootsector *bsp;
416 	struct byte_bpb33 *b33;
417 	struct byte_bpb50 *b50;
418 	struct byte_bpb710 *b710;
419 	u_int8_t SecPerClust;
420 	u_long clusters;
421 	int ronly, error;
422 	struct g_consumer *cp;
423 	struct bufobj *bo;
424 
425 	bp = NULL;		/* This and pmp both used in error_exit. */
426 	pmp = NULL;
427 	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
428 
429 	dev = devvp->v_rdev;
430 	dev_ref(dev);
431 	DROP_GIANT();
432 	g_topology_lock();
433 	error = g_vfs_open(devvp, &cp, "msdosfs", ronly ? 0 : 1);
434 	g_topology_unlock();
435 	PICKUP_GIANT();
436 	VOP_UNLOCK(devvp, 0);
437 	if (error)
438 		goto error_exit;
439 
440 	bo = &devvp->v_bufobj;
441 
442 	/*
443 	 * Read the boot sector of the filesystem, and then check the
444 	 * boot signature.  If not a dos boot sector then error out.
445 	 *
446 	 * NOTE: 8192 is a magic size that works for ffs.
447 	 */
448 	error = bread(devvp, 0, 8192, NOCRED, &bp);
449 	if (error)
450 		goto error_exit;
451 	bp->b_flags |= B_AGE;
452 	bsp = (union bootsector *)bp->b_data;
453 	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
454 	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
455 	b710 = (struct byte_bpb710 *)bsp->bs710.bsBPB;
456 
457 #ifndef MSDOSFS_NOCHECKSIG
458 	if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
459 	    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
460 		error = EINVAL;
461 		goto error_exit;
462 	}
463 #endif
464 
465 	pmp = malloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK | M_ZERO);
466 	pmp->pm_mountp = mp;
467 	pmp->pm_cp = cp;
468 	pmp->pm_bo = bo;
469 
470 	lockinit(&pmp->pm_fatlock, 0, msdosfs_lock_msg, 0, 0);
471 
472 	/*
473 	 * Initialize ownerships and permissions, since nothing else will
474 	 * initialize them iff we are mounting root.
475 	 */
476 	pmp->pm_uid = UID_ROOT;
477 	pmp->pm_gid = GID_WHEEL;
478 	pmp->pm_mask = pmp->pm_dirmask = S_IXUSR | S_IXGRP | S_IXOTH |
479 	    S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR;
480 
481 	/*
482 	 * Experimental support for large MS-DOS filesystems.
483 	 * WARNING: This uses at least 32 bytes of kernel memory (which is not
484 	 * reclaimed until the FS is unmounted) for each file on disk to map
485 	 * between the 32-bit inode numbers used by VFS and the 64-bit
486 	 * pseudo-inode numbers used internally by msdosfs. This is only
487 	 * safe to use in certain controlled situations (e.g. read-only FS
488 	 * with less than 1 million files).
489 	 * Since the mappings do not persist across unmounts (or reboots), these
490 	 * filesystems are not suitable for exporting through NFS, or any other
491 	 * application that requires fixed inode numbers.
492 	 */
493 	vfs_flagopt(mp->mnt_optnew, "large", &pmp->pm_flags, MSDOSFS_LARGEFS);
494 
495 	/*
496 	 * Compute several useful quantities from the bpb in the
497 	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
498 	 * the fields that are different between dos 5 and dos 3.3.
499 	 */
500 	SecPerClust = b50->bpbSecPerClust;
501 	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
502 	if (pmp->pm_BytesPerSec < DEV_BSIZE) {
503 		error = EINVAL;
504 		goto error_exit;
505 	}
506 	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
507 	pmp->pm_FATs = b50->bpbFATs;
508 	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
509 	pmp->pm_Sectors = getushort(b50->bpbSectors);
510 	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
511 	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
512 	pmp->pm_Heads = getushort(b50->bpbHeads);
513 	pmp->pm_Media = b50->bpbMedia;
514 
515 	/* calculate the ratio of sector size to DEV_BSIZE */
516 	pmp->pm_BlkPerSec = pmp->pm_BytesPerSec / DEV_BSIZE;
517 
518 	/*
519 	 * We don't check pm_Heads nor pm_SecPerTrack, because
520 	 * these may not be set for EFI file systems. We don't
521 	 * use these anyway, so we're unaffected if they are
522 	 * invalid.
523 	 */
524 	if (!pmp->pm_BytesPerSec || !SecPerClust) {
525 		error = EINVAL;
526 		goto error_exit;
527 	}
528 
529 	if (pmp->pm_Sectors == 0) {
530 		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
531 		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
532 	} else {
533 		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
534 		pmp->pm_HugeSectors = pmp->pm_Sectors;
535 	}
536 	if (!(pmp->pm_flags & MSDOSFS_LARGEFS)) {
537 		if (pmp->pm_HugeSectors > 0xffffffff /
538 		    (pmp->pm_BytesPerSec / sizeof(struct direntry)) + 1) {
539 			/*
540 			 * We cannot deal currently with this size of disk
541 			 * due to fileid limitations (see msdosfs_getattr and
542 			 * msdosfs_readdir)
543 			 */
544 			error = EINVAL;
545 			vfs_mount_error(mp,
546 			    "Disk too big, try '-o large' mount option");
547 			goto error_exit;
548 		}
549 	}
550 
551 	if (pmp->pm_RootDirEnts == 0) {
552 		if (pmp->pm_Sectors
553 		    || pmp->pm_FATsecs
554 		    || getushort(b710->bpbFSVers)) {
555 			error = EINVAL;
556 			printf("mountmsdosfs(): bad FAT32 filesystem\n");
557 			goto error_exit;
558 		}
559 		pmp->pm_fatmask = FAT32_MASK;
560 		pmp->pm_fatmult = 4;
561 		pmp->pm_fatdiv = 1;
562 		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);
563 		if (getushort(b710->bpbExtFlags) & FATMIRROR)
564 			pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
565 		else
566 			pmp->pm_flags |= MSDOSFS_FATMIRROR;
567 	} else
568 		pmp->pm_flags |= MSDOSFS_FATMIRROR;
569 
570 	/*
571 	 * Check a few values (could do some more):
572 	 * - logical sector size: power of 2, >= block size
573 	 * - sectors per cluster: power of 2, >= 1
574 	 * - number of sectors:   >= 1, <= size of partition
575 	 * - number of FAT sectors: >= 1
576 	 */
577 	if ( (SecPerClust == 0)
578 	  || (SecPerClust & (SecPerClust - 1))
579 	  || (pmp->pm_BytesPerSec < DEV_BSIZE)
580 	  || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
581 	  || (pmp->pm_HugeSectors == 0)
582 	  || (pmp->pm_FATsecs == 0)
583 	  || (SecPerClust * pmp->pm_BlkPerSec > MAXBSIZE / DEV_BSIZE)
584 	) {
585 		error = EINVAL;
586 		goto error_exit;
587 	}
588 
589 	pmp->pm_HugeSectors *= pmp->pm_BlkPerSec;
590 	pmp->pm_HiddenSects *= pmp->pm_BlkPerSec;	/* XXX not used? */
591 	pmp->pm_FATsecs     *= pmp->pm_BlkPerSec;
592 	SecPerClust         *= pmp->pm_BlkPerSec;
593 
594 	pmp->pm_fatblk = pmp->pm_ResSectors * pmp->pm_BlkPerSec;
595 
596 	if (FAT32(pmp)) {
597 		pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
598 		pmp->pm_firstcluster = pmp->pm_fatblk
599 			+ (pmp->pm_FATs * pmp->pm_FATsecs);
600 		pmp->pm_fsinfo = getushort(b710->bpbFSInfo) * pmp->pm_BlkPerSec;
601 	} else {
602 		pmp->pm_rootdirblk = pmp->pm_fatblk +
603 			(pmp->pm_FATs * pmp->pm_FATsecs);
604 		pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
605 				       + DEV_BSIZE - 1)
606 			/ DEV_BSIZE; /* in blocks */
607 		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
608 	}
609 
610 	pmp->pm_maxcluster = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
611 	    SecPerClust + 1;
612 	pmp->pm_fatsize = pmp->pm_FATsecs * DEV_BSIZE;	/* XXX not used? */
613 
614 	if (pmp->pm_fatmask == 0) {
615 		if (pmp->pm_maxcluster
616 		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
617 			/*
618 			 * This will usually be a floppy disk. This size makes
619 			 * sure that one fat entry will not be split across
620 			 * multiple blocks.
621 			 */
622 			pmp->pm_fatmask = FAT12_MASK;
623 			pmp->pm_fatmult = 3;
624 			pmp->pm_fatdiv = 2;
625 		} else {
626 			pmp->pm_fatmask = FAT16_MASK;
627 			pmp->pm_fatmult = 2;
628 			pmp->pm_fatdiv = 1;
629 		}
630 	}
631 
632 	clusters = (pmp->pm_fatsize / pmp->pm_fatmult) * pmp->pm_fatdiv;
633 	if (pmp->pm_maxcluster >= clusters) {
634 		printf("Warning: number of clusters (%ld) exceeds FAT "
635 		    "capacity (%ld)\n", pmp->pm_maxcluster + 1, clusters);
636 		pmp->pm_maxcluster = clusters - 1;
637 	}
638 
639 	if (FAT12(pmp))
640 		pmp->pm_fatblocksize = 3 * 512;
641 	else
642 		pmp->pm_fatblocksize = PAGE_SIZE;
643 	pmp->pm_fatblocksize = roundup(pmp->pm_fatblocksize,
644 	    pmp->pm_BytesPerSec);
645 	pmp->pm_fatblocksec = pmp->pm_fatblocksize / DEV_BSIZE;
646 	pmp->pm_bnshift = ffs(DEV_BSIZE) - 1;
647 
648 	/*
649 	 * Compute mask and shift value for isolating cluster relative byte
650 	 * offsets and cluster numbers from a file offset.
651 	 */
652 	pmp->pm_bpcluster = SecPerClust * DEV_BSIZE;
653 	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
654 	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;
655 
656 	/*
657 	 * Check for valid cluster size
658 	 * must be a power of 2
659 	 */
660 	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
661 		error = EINVAL;
662 		goto error_exit;
663 	}
664 
665 	/*
666 	 * Release the bootsector buffer.
667 	 */
668 	brelse(bp);
669 	bp = NULL;
670 
671 	/*
672 	 * Check the fsinfo sector if we have one.  Silently fix up our
673 	 * in-core copy of fp->fsinxtfree if it is unknown (0xffffffff)
674 	 * or too large.  Ignore fp->fsinfree for now, since we need to
675 	 * read the entire FAT anyway to fill the inuse map.
676 	 */
677 	if (pmp->pm_fsinfo) {
678 		struct fsinfo *fp;
679 
680 		if ((error = bread(devvp, pmp->pm_fsinfo, pmp->pm_BytesPerSec,
681 		    NOCRED, &bp)) != 0)
682 			goto error_exit;
683 		fp = (struct fsinfo *)bp->b_data;
684 		if (!bcmp(fp->fsisig1, "RRaA", 4)
685 		    && !bcmp(fp->fsisig2, "rrAa", 4)
686 		    && !bcmp(fp->fsisig3, "\0\0\125\252", 4)) {
687 			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
688 			if (pmp->pm_nxtfree > pmp->pm_maxcluster)
689 				pmp->pm_nxtfree = CLUST_FIRST;
690 		} else
691 			pmp->pm_fsinfo = 0;
692 		brelse(bp);
693 		bp = NULL;
694 	}
695 
696 	/*
697 	 * Finish initializing pmp->pm_nxtfree (just in case the first few
698 	 * sectors aren't properly reserved in the FAT).  This completes
699 	 * the fixup for fp->fsinxtfree, and fixes up the zero-initialized
700 	 * value if there is no fsinfo.  We will use pmp->pm_nxtfree
701 	 * internally even if there is no fsinfo.
702 	 */
703 	if (pmp->pm_nxtfree < CLUST_FIRST)
704 		pmp->pm_nxtfree = CLUST_FIRST;
705 
706 	/*
707 	 * Allocate memory for the bitmap of allocated clusters, and then
708 	 * fill it in.
709 	 */
710 	pmp->pm_inusemap = malloc(howmany(pmp->pm_maxcluster + 1, N_INUSEBITS)
711 				  * sizeof(*pmp->pm_inusemap),
712 				  M_MSDOSFSFAT, M_WAITOK);
713 
714 	/*
715 	 * fillinusemap() needs pm_devvp.
716 	 */
717 	pmp->pm_devvp = devvp;
718 	pmp->pm_dev = dev;
719 
720 	/*
721 	 * Have the inuse map filled in.
722 	 */
723 	MSDOSFS_LOCK_MP(pmp);
724 	error = fillinusemap(pmp);
725 	MSDOSFS_UNLOCK_MP(pmp);
726 	if (error != 0)
727 		goto error_exit;
728 
729 	/*
730 	 * If they want fat updates to be synchronous then let them suffer
731 	 * the performance degradation in exchange for the on disk copy of
732 	 * the fat being correct just about all the time.  I suppose this
733 	 * would be a good thing to turn on if the kernel is still flakey.
734 	 */
735 	if (mp->mnt_flag & MNT_SYNCHRONOUS)
736 		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;
737 
738 	/*
739 	 * Finish up.
740 	 */
741 	if (ronly)
742 		pmp->pm_flags |= MSDOSFSMNT_RONLY;
743 	else {
744 		if ((error = markvoldirty(pmp, 1)) != 0) {
745 			(void)markvoldirty(pmp, 0);
746 			goto error_exit;
747 		}
748 		pmp->pm_fmod = 1;
749 	}
750 	mp->mnt_data =  pmp;
751 	mp->mnt_stat.f_fsid.val[0] = dev2udev(dev);
752 	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
753 	MNT_ILOCK(mp);
754 	mp->mnt_flag |= MNT_LOCAL;
755 	mp->mnt_kern_flag |= MNTK_MPSAFE;
756 	MNT_IUNLOCK(mp);
757 
758 	if (pmp->pm_flags & MSDOSFS_LARGEFS)
759 		msdosfs_fileno_init(mp);
760 
761 	return 0;
762 
763 error_exit:
764 	if (bp)
765 		brelse(bp);
766 	if (cp != NULL) {
767 		DROP_GIANT();
768 		g_topology_lock();
769 		g_vfs_close(cp);
770 		g_topology_unlock();
771 		PICKUP_GIANT();
772 	}
773 	if (pmp) {
774 		lockdestroy(&pmp->pm_fatlock);
775 		if (pmp->pm_inusemap)
776 			free(pmp->pm_inusemap, M_MSDOSFSFAT);
777 		free(pmp, M_MSDOSFSMNT);
778 		mp->mnt_data = NULL;
779 	}
780 	dev_rel(dev);
781 	return (error);
782 }
783 
784 /*
785  * Unmount the filesystem described by mp.
786  */
787 static int
788 msdosfs_unmount(struct mount *mp, int mntflags)
789 {
790 	struct msdosfsmount *pmp;
791 	int error, flags;
792 
793 	flags = 0;
794 	if (mntflags & MNT_FORCE)
795 		flags |= FORCECLOSE;
796 	error = vflush(mp, 0, flags, curthread);
797 	if (error && error != ENXIO)
798 		return error;
799 	pmp = VFSTOMSDOSFS(mp);
800 	if ((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0) {
801 		error = markvoldirty(pmp, 0);
802 		if (error && error != ENXIO) {
803 			(void)markvoldirty(pmp, 1);
804 			return (error);
805 		}
806 	}
807 	if (pmp->pm_flags & MSDOSFSMNT_KICONV && msdosfs_iconv) {
808 		if (pmp->pm_w2u)
809 			msdosfs_iconv->close(pmp->pm_w2u);
810 		if (pmp->pm_u2w)
811 			msdosfs_iconv->close(pmp->pm_u2w);
812 		if (pmp->pm_d2u)
813 			msdosfs_iconv->close(pmp->pm_d2u);
814 		if (pmp->pm_u2d)
815 			msdosfs_iconv->close(pmp->pm_u2d);
816 	}
817 
818 #ifdef MSDOSFS_DEBUG
819 	{
820 		struct vnode *vp = pmp->pm_devvp;
821 		struct bufobj *bo;
822 
823 		bo = &vp->v_bufobj;
824 		BO_LOCK(bo);
825 		VI_LOCK(vp);
826 		vn_printf(vp,
827 		    "msdosfs_umount(): just before calling VOP_CLOSE()\n");
828 		printf("freef %p, freeb %p, mount %p\n",
829 		    TAILQ_NEXT(vp, v_freelist), vp->v_freelist.tqe_prev,
830 		    vp->v_mount);
831 		printf("cleanblkhd %p, dirtyblkhd %p, numoutput %ld, type %d\n",
832 		    TAILQ_FIRST(&vp->v_bufobj.bo_clean.bv_hd),
833 		    TAILQ_FIRST(&vp->v_bufobj.bo_dirty.bv_hd),
834 		    vp->v_bufobj.bo_numoutput, vp->v_type);
835 		VI_UNLOCK(vp);
836 		BO_UNLOCK(bo);
837 	}
838 #endif
839 	DROP_GIANT();
840 	g_topology_lock();
841 	g_vfs_close(pmp->pm_cp);
842 	g_topology_unlock();
843 	PICKUP_GIANT();
844 	vrele(pmp->pm_devvp);
845 	dev_rel(pmp->pm_dev);
846 	free(pmp->pm_inusemap, M_MSDOSFSFAT);
847 	if (pmp->pm_flags & MSDOSFS_LARGEFS)
848 		msdosfs_fileno_free(mp);
849 	lockdestroy(&pmp->pm_fatlock);
850 	free(pmp, M_MSDOSFSMNT);
851 	mp->mnt_data = NULL;
852 	MNT_ILOCK(mp);
853 	mp->mnt_flag &= ~MNT_LOCAL;
854 	MNT_IUNLOCK(mp);
855 	return (error);
856 }
857 
858 static int
859 msdosfs_root(struct mount *mp, int flags, struct vnode **vpp)
860 {
861 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
862 	struct denode *ndep;
863 	int error;
864 
865 #ifdef MSDOSFS_DEBUG
866 	printf("msdosfs_root(); mp %p, pmp %p\n", mp, pmp);
867 #endif
868 	error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, &ndep);
869 	if (error)
870 		return (error);
871 	*vpp = DETOV(ndep);
872 	return (0);
873 }
874 
875 static int
876 msdosfs_statfs(struct mount *mp, struct statfs *sbp)
877 {
878 	struct msdosfsmount *pmp;
879 
880 	pmp = VFSTOMSDOSFS(mp);
881 	sbp->f_bsize = pmp->pm_bpcluster;
882 	sbp->f_iosize = pmp->pm_bpcluster;
883 	sbp->f_blocks = pmp->pm_maxcluster + 1;
884 	sbp->f_bfree = pmp->pm_freeclustercount;
885 	sbp->f_bavail = pmp->pm_freeclustercount;
886 	sbp->f_files = pmp->pm_RootDirEnts;	/* XXX */
887 	sbp->f_ffree = 0;	/* what to put in here? */
888 	return (0);
889 }
890 
891 static int
892 msdosfs_sync(struct mount *mp, int waitfor)
893 {
894 	struct vnode *vp, *nvp;
895 	struct thread *td;
896 	struct denode *dep;
897 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
898 	int error, allerror = 0;
899 
900 	td = curthread;
901 
902 	/*
903 	 * If we ever switch to not updating all of the fats all the time,
904 	 * this would be the place to update them from the first one.
905 	 */
906 	if (pmp->pm_fmod != 0) {
907 		if (pmp->pm_flags & MSDOSFSMNT_RONLY)
908 			panic("msdosfs_sync: rofs mod");
909 		else {
910 			/* update fats here */
911 		}
912 	}
913 	/*
914 	 * Write back each (modified) denode.
915 	 */
916 	MNT_ILOCK(mp);
917 loop:
918 	MNT_VNODE_FOREACH(vp, mp, nvp) {
919 		VI_LOCK(vp);
920 		if (vp->v_type == VNON || (vp->v_iflag & VI_DOOMED)) {
921 			VI_UNLOCK(vp);
922 			continue;
923 		}
924 		MNT_IUNLOCK(mp);
925 		dep = VTODE(vp);
926 		if ((dep->de_flag &
927 		    (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0 &&
928 		    (vp->v_bufobj.bo_dirty.bv_cnt == 0 ||
929 		    waitfor == MNT_LAZY)) {
930 			VI_UNLOCK(vp);
931 			MNT_ILOCK(mp);
932 			continue;
933 		}
934 		error = vget(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, td);
935 		if (error) {
936 			MNT_ILOCK(mp);
937 			if (error == ENOENT)
938 				goto loop;
939 			continue;
940 		}
941 		error = VOP_FSYNC(vp, waitfor, td);
942 		if (error)
943 			allerror = error;
944 		VOP_UNLOCK(vp, 0);
945 		vrele(vp);
946 		MNT_ILOCK(mp);
947 	}
948 	MNT_IUNLOCK(mp);
949 
950 	/*
951 	 * Flush filesystem control info.
952 	 */
953 	if (waitfor != MNT_LAZY) {
954 		vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY);
955 		error = VOP_FSYNC(pmp->pm_devvp, waitfor, td);
956 		if (error)
957 			allerror = error;
958 		VOP_UNLOCK(pmp->pm_devvp, 0);
959 	}
960 	return (allerror);
961 }
962 
963 static int
964 msdosfs_fhtovp(struct mount *mp, struct fid *fhp, struct vnode **vpp)
965 {
966 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
967 	struct defid *defhp = (struct defid *) fhp;
968 	struct denode *dep;
969 	int error;
970 
971 	error = deget(pmp, defhp->defid_dirclust, defhp->defid_dirofs, &dep);
972 	if (error) {
973 		*vpp = NULLVP;
974 		return (error);
975 	}
976 	*vpp = DETOV(dep);
977 	vnode_create_vobject(*vpp, dep->de_FileSize, curthread);
978 	return (0);
979 }
980 
981 static struct vfsops msdosfs_vfsops = {
982 	.vfs_fhtovp =		msdosfs_fhtovp,
983 	.vfs_mount =		msdosfs_mount,
984 	.vfs_cmount =		msdosfs_cmount,
985 	.vfs_root =		msdosfs_root,
986 	.vfs_statfs =		msdosfs_statfs,
987 	.vfs_sync =		msdosfs_sync,
988 	.vfs_unmount =		msdosfs_unmount,
989 };
990 
991 VFS_SET(msdosfs_vfsops, msdosfs, 0);
992 MODULE_VERSION(msdosfs, 1);
993