xref: /dragonfly/sys/vfs/msdosfs/msdosfs_vfsops.c (revision e293de53)
1 /* $FreeBSD: /usr/local/www/cvsroot/FreeBSD/src/sys/msdosfs/Attic/msdosfs_vfsops.c,v 1.60.2.8 2004/03/02 09:43:04 tjr Exp $ */
2 /* $DragonFly: src/sys/vfs/msdosfs/msdosfs_vfsops.c,v 1.52 2008/09/17 21:44:24 dillon Exp $ */
3 /*	$NetBSD: msdosfs_vfsops.c,v 1.51 1997/11/17 15:36:58 ws Exp $	*/
4 
5 /*-
6  * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
7  * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
8  * All rights reserved.
9  * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. All advertising materials mentioning features or use of this software
20  *    must display the following acknowledgement:
21  *	This product includes software developed by TooLs GmbH.
22  * 4. The name of TooLs GmbH may not be used to endorse or promote products
23  *    derived from this software without specific prior written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
26  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
27  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
28  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
29  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
30  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
31  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
32  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
33  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
34  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35  */
36 /*
37  * Written by Paul Popelka (paulp@uts.amdahl.com)
38  *
39  * You can do anything you want with this software, just don't say you wrote
40  * it, and don't remove this notice.
41  *
42  * This software is provided "as is".
43  *
44  * The author supplies this software to be publicly redistributed on the
45  * understanding that the author is not responsible for the correct
46  * functioning of this software in any circumstances and is not liable for
47  * any damages caused by this software.
48  *
49  * October 1992
50  */
51 
52 #include <sys/param.h>
53 #include <sys/systm.h>
54 #include <sys/conf.h>
55 #include <sys/proc.h>
56 #include <sys/nlookup.h>
57 #include <sys/kernel.h>
58 #include <sys/vnode.h>
59 #include <sys/mount.h>
60 #include <sys/buf.h>
61 #include <sys/fcntl.h>
62 #include <sys/malloc.h>
63 #include <sys/stat.h> 				/* defines ALLPERMS */
64 #include <vm/vm_zone.h>
65 
66 #include "bpb.h"
67 #include "bootsect.h"
68 #include "direntry.h"
69 #include "denode.h"
70 #include "msdosfsmount.h"
71 #include "fat.h"
72 
73 extern struct vop_ops msdosfs_vnode_vops;
74 
75 #define MSDOSFS_DFLTBSIZE       4096
76 
77 #if 1 /*def PC98*/
78 /*
79  * XXX - The boot signature formatted by NEC PC-98 DOS looks like a
80  *       garbage or a random value :-{
81  *       If you want to use that broken-signatured media, define the
82  *       following symbol even though PC/AT.
83  *       (ex. mount PC-98 DOS formatted FD on PC/AT)
84  */
85 #define	MSDOSFS_NOCHECKSIG
86 #endif
87 
88 MALLOC_DEFINE(M_MSDOSFSMNT, "MSDOSFS mount", "MSDOSFS mount structure");
89 static MALLOC_DEFINE(M_MSDOSFSFAT, "MSDOSFS FAT", "MSDOSFS file allocation table");
90 
91 static int	update_mp (struct mount *mp, struct msdosfs_args *argp);
92 static int	mountmsdosfs (struct vnode *devvp, struct mount *mp,
93 				  struct msdosfs_args *argp);
94 static int	msdosfs_fhtovp (struct mount *, struct vnode *,
95 				struct fid *, struct vnode **);
96 static int	msdosfs_checkexp (struct mount *, struct sockaddr *,
97 				    int *, struct ucred **);
98 static int	msdosfs_mount (struct mount *, char *, caddr_t,
99 				   struct ucred *);
100 static int	msdosfs_root (struct mount *, struct vnode **);
101 static int	msdosfs_statfs (struct mount *, struct statfs *,
102 				struct ucred *);
103 static int	msdosfs_sync (struct mount *, int);
104 static int	msdosfs_unmount (struct mount *, int);
105 static int	msdosfs_vptofh (struct vnode *, struct fid *);
106 
107 static int
108 update_mp(struct mount *mp, struct msdosfs_args *argp)
109 {
110 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
111 	int error;
112 
113 	pmp->pm_gid = argp->gid;
114 	pmp->pm_uid = argp->uid;
115 	pmp->pm_mask = argp->mask & ALLPERMS;
116 	pmp->pm_flags |= argp->flags & MSDOSFSMNT_MNTOPT;
117 	if (pmp->pm_flags & MSDOSFSMNT_U2WTABLE) {
118 		bcopy(argp->u2w, pmp->pm_u2w, sizeof(pmp->pm_u2w));
119 		bcopy(argp->d2u, pmp->pm_d2u, sizeof(pmp->pm_d2u));
120 		bcopy(argp->u2d, pmp->pm_u2d, sizeof(pmp->pm_u2d));
121 	}
122 	if (pmp->pm_flags & MSDOSFSMNT_ULTABLE) {
123 		bcopy(argp->ul, pmp->pm_ul, sizeof(pmp->pm_ul));
124 		bcopy(argp->lu, pmp->pm_lu, sizeof(pmp->pm_lu));
125 	}
126 
127 	if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
128 		pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
129 	else if (!(pmp->pm_flags &
130 	    (MSDOSFSMNT_SHORTNAME | MSDOSFSMNT_LONGNAME))) {
131 		struct vnode *rootvp;
132 
133 		/*
134 		 * Try to divine whether to support Win'95 long filenames
135 		 */
136 		if (FAT32(pmp))
137 			pmp->pm_flags |= MSDOSFSMNT_LONGNAME;
138 		else {
139 			if ((error = msdosfs_root(mp, &rootvp)) != 0)
140 				return error;
141 			pmp->pm_flags |= findwin95(VTODE(rootvp))
142 				? MSDOSFSMNT_LONGNAME
143 					: MSDOSFSMNT_SHORTNAME;
144 			vput(rootvp);
145 		}
146 	}
147 	return 0;
148 }
149 
150 /*
151  * mp - path - addr in user space of mount point (ie /usr or whatever)
152  * data - addr in user space of mount params including the name of the block
153  * special file to treat as a filesystem.
154  */
155 static int
156 msdosfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred)
157 {
158 	struct vnode *devvp;	  /* vnode for blk device to mount */
159 	struct msdosfs_args args; /* will hold data from mount request */
160 	/* msdosfs specific mount control block */
161 	struct msdosfsmount *pmp = NULL;
162 	size_t size;
163 	int error, flags;
164 	mode_t accessmode;
165 	struct nlookupdata nd;
166 
167 	error = copyin(data, (caddr_t)&args, sizeof(struct msdosfs_args));
168 	if (error)
169 		return (error);
170 	if (args.magic != MSDOSFS_ARGSMAGIC)
171 		args.flags = 0;
172 	/*
173 	 * If updating, check whether changing from read-only to
174 	 * read/write; if there is no device name, that's all we do.
175 	 */
176 	if (mp->mnt_flag & MNT_UPDATE) {
177 		pmp = VFSTOMSDOSFS(mp);
178 		error = 0;
179 		if (!(pmp->pm_flags & MSDOSFSMNT_RONLY) && (mp->mnt_flag & MNT_RDONLY)) {
180 			flags = WRITECLOSE;
181 			if (mp->mnt_flag & MNT_FORCE)
182 				flags |= FORCECLOSE;
183 			error = vflush(mp, 0, flags);
184 			if (error == 0) {
185 				devvp = pmp->pm_devvp;
186 				VOP_OPEN(devvp, FREAD, FSCRED, NULL);
187 				VOP_CLOSE(devvp, FREAD|FWRITE);
188 				pmp->pm_flags |= MSDOSFSMNT_RONLY;
189 			}
190 		}
191 		if (!error && (mp->mnt_flag & MNT_RELOAD))
192 			/* not yet implemented */
193 			error = EOPNOTSUPP;
194 		if (error)
195 			return (error);
196 		if ((pmp->pm_flags & MSDOSFSMNT_RONLY) && (mp->mnt_kern_flag & MNTK_WANTRDWR)) {
197 			/*
198 			 * If upgrade to read-write by non-root, then verify
199 			 * that user has necessary permissions on the device.
200 			 */
201 			devvp = pmp->pm_devvp;
202 			vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
203 			if (cred->cr_uid != 0) {
204 				error = VOP_ACCESS(devvp, VREAD | VWRITE, cred);
205 				if (error) {
206 					vn_unlock(devvp);
207 					return (error);
208 				}
209 			}
210 			VOP_OPEN(devvp, FREAD|FWRITE, FSCRED, NULL);
211 			VOP_CLOSE(devvp, FREAD);
212 			vn_unlock(devvp);
213 			pmp->pm_flags &= ~MSDOSFSMNT_RONLY;
214 		}
215 		if (args.fspec == 0) {
216 #ifdef	__notyet__		/* doesn't work correctly with current mountd	XXX */
217 			if (args.flags & MSDOSFSMNT_MNTOPT) {
218 				pmp->pm_flags &= ~MSDOSFSMNT_MNTOPT;
219 				pmp->pm_flags |= args.flags & MSDOSFSMNT_MNTOPT;
220 				if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
221 					pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
222 			}
223 #endif
224 			/*
225 			 * Process export requests.
226 			 */
227 			return (vfs_export(mp, &pmp->pm_export, &args.export));
228 		}
229 	}
230 	/*
231 	 * Not an update, or updating the name: look up the name
232 	 * and verify that it refers to a sensible block device.
233 	 */
234 	devvp = NULL;
235 	error = nlookup_init(&nd, args.fspec, UIO_USERSPACE, NLC_FOLLOW);
236 	if (error == 0)
237 		error = nlookup(&nd);
238 	if (error == 0)
239 		error = cache_vref(&nd.nl_nch, nd.nl_cred, &devvp);
240 	nlookup_done(&nd);
241 	if (error)
242 		return (error);
243 
244 	if (!vn_isdisk(devvp, &error)) {
245 		vrele(devvp);
246 		return (error);
247 	}
248 	/*
249 	 * If mount by non-root, then verify that user has necessary
250 	 * permissions on the device.
251 	 */
252 	if (cred->cr_uid != 0) {
253 		accessmode = VREAD;
254 		if ((mp->mnt_flag & MNT_RDONLY) == 0)
255 			accessmode |= VWRITE;
256 		vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
257 		error = VOP_ACCESS(devvp, accessmode, cred);
258 		if (error) {
259 			vput(devvp);
260 			return (error);
261 		}
262 		vn_unlock(devvp);
263 	}
264 	if ((mp->mnt_flag & MNT_UPDATE) == 0) {
265 		error = mountmsdosfs(devvp, mp, &args);
266 #ifdef MSDOSFS_DEBUG		/* only needed for the kprintf below */
267 		pmp = VFSTOMSDOSFS(mp);
268 #endif
269 	} else {
270 		if (devvp != pmp->pm_devvp)
271 			error = EINVAL;	/* XXX needs translation */
272 		else
273 			vrele(devvp);
274 	}
275 	if (error) {
276 		vrele(devvp);
277 		return (error);
278 	}
279 
280 	error = update_mp(mp, &args);
281 	if (error) {
282 		msdosfs_unmount(mp, MNT_FORCE);
283 		return error;
284 	}
285 
286 	copyinstr(args.fspec, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, &size);
287 	bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size);
288 	msdosfs_statfs(mp, &mp->mnt_stat, cred);
289 #ifdef MSDOSFS_DEBUG
290 	kprintf("msdosfs_mount(): mp %p, pmp %p, inusemap %p\n", mp, pmp, pmp->pm_inusemap);
291 #endif
292 	return (0);
293 }
294 
295 static int
296 mountmsdosfs(struct vnode *devvp, struct mount *mp, struct msdosfs_args *argp)
297 {
298 	struct msdosfsmount *pmp;
299 	struct buf *bp;
300 	cdev_t dev;
301 	union bootsector *bsp;
302 	struct byte_bpb33 *b33;
303 	struct byte_bpb50 *b50;
304 	struct byte_bpb710 *b710;
305 	u_int8_t SecPerClust;
306 	u_long clusters;
307 	int	ronly, error;
308 
309 	/*
310 	 * Disallow multiple mounts of the same device.
311 	 * Disallow mounting of a device that is currently in use
312 	 * Flush out any old buffers remaining from a previous use.
313 	 */
314 	error = vfs_mountedon(devvp);
315 	if (error)
316 		return (error);
317 	if (count_udev(devvp->v_umajor, devvp->v_uminor) > 0)
318 		return (EBUSY);
319 	vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
320 	error = vinvalbuf(devvp, V_SAVE, 0, 0);
321 	vn_unlock(devvp);
322 	if (error)
323 		return (error);
324 
325 	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
326 	vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
327 	error = VOP_OPEN(devvp, ronly ? FREAD : FREAD|FWRITE, FSCRED, NULL);
328 	vn_unlock(devvp);
329 	if (error)
330 		return (error);
331 	dev = devvp->v_rdev;
332 	bp  = NULL; /* both used in error_exit */
333 	pmp = NULL;
334 
335 	/*
336 	 * Read the boot sector of the filesystem, and then check the
337 	 * boot signature.  If not a dos boot sector then error out.
338 	 *
339 	 * NOTE: 2048 is a maximum sector size in current...
340 	 */
341 	error = bread(devvp, 0, 2048, &bp);
342 	if (error)
343 		goto error_exit;
344 	bp->b_flags |= B_AGE;
345 	bsp = (union bootsector *)bp->b_data;
346 	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
347 	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
348 	b710 = (struct byte_bpb710 *)bsp->bs710.bsPBP;
349 
350 #ifndef MSDOSFS_NOCHECKSIG
351 	if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
352 	    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
353 		error = EINVAL;
354 		goto error_exit;
355 	}
356 #endif
357 
358 	pmp = kmalloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK | M_ZERO);
359 	pmp->pm_mountp = mp;
360 
361 	/*
362 	 * Compute several useful quantities from the bpb in the
363 	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
364 	 * the fields that are different between dos 5 and dos 3.3.
365 	 */
366 	SecPerClust = b50->bpbSecPerClust;
367 	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
368 	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
369 	pmp->pm_FATs = b50->bpbFATs;
370 	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
371 	pmp->pm_Sectors = getushort(b50->bpbSectors);
372 	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
373 	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
374 	pmp->pm_Heads = getushort(b50->bpbHeads);
375 	pmp->pm_Media = b50->bpbMedia;
376 
377 	/* calculate the ratio of sector size to DEV_BSIZE */
378 	pmp->pm_BlkPerSec = pmp->pm_BytesPerSec / DEV_BSIZE;
379 
380 	/*
381 	 * We don't check pm_Heads nor pm_SecPerTrack, because
382 	 * these may not be set for EFI file systems. We don't
383 	 * use these anyway, so we're unaffected if they are
384 	 * invalid.
385 	 */
386 	if (!pmp->pm_BytesPerSec || !SecPerClust) {
387 		error = EINVAL;
388 		goto error_exit;
389 	}
390 
391 	if (pmp->pm_Sectors == 0) {
392 		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
393 		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
394 	} else {
395 		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
396 		pmp->pm_HugeSectors = pmp->pm_Sectors;
397 	}
398 
399 	if (pmp->pm_RootDirEnts == 0) {
400 		if (pmp->pm_Sectors
401 		    || pmp->pm_FATsecs
402 		    || getushort(b710->bpbFSVers)) {
403 			error = EINVAL;
404 			kprintf("mountmsdosfs(): bad FAT32 filesystem\n");
405 			goto error_exit;
406 		}
407 		pmp->pm_fatmask = FAT32_MASK;
408 		pmp->pm_fatmult = 4;
409 		pmp->pm_fatdiv = 1;
410 		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);
411 		if (getushort(b710->bpbExtFlags) & FATMIRROR)
412 			pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
413 		else
414 			pmp->pm_flags |= MSDOSFS_FATMIRROR;
415 	} else
416 		pmp->pm_flags |= MSDOSFS_FATMIRROR;
417 
418 	/*
419 	 * Check a few values (could do some more):
420 	 * - logical sector size: power of 2, >= block size
421 	 * - sectors per cluster: power of 2, >= 1
422 	 * - number of sectors:   >= 1, <= size of partition
423 	 */
424 	if ( (SecPerClust == 0)
425 	  || (SecPerClust & (SecPerClust - 1))
426 	  || (pmp->pm_BytesPerSec < DEV_BSIZE)
427 	  || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
428 	  || (pmp->pm_HugeSectors == 0)
429 	) {
430 		error = EINVAL;
431 		goto error_exit;
432 	}
433 
434 	pmp->pm_HugeSectors *= pmp->pm_BlkPerSec;
435 	pmp->pm_HiddenSects *= pmp->pm_BlkPerSec; /* XXX not used? */
436 	pmp->pm_FATsecs     *= pmp->pm_BlkPerSec;
437 	SecPerClust         *= pmp->pm_BlkPerSec;
438 
439 	pmp->pm_fatblk = pmp->pm_ResSectors * pmp->pm_BlkPerSec;
440 
441 	if (FAT32(pmp)) {
442 		pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
443 		pmp->pm_firstcluster = pmp->pm_fatblk
444 			+ (pmp->pm_FATs * pmp->pm_FATsecs);
445 		pmp->pm_fsinfo = getushort(b710->bpbFSInfo) * pmp->pm_BlkPerSec;
446 	} else {
447 		pmp->pm_rootdirblk = pmp->pm_fatblk +
448 			(pmp->pm_FATs * pmp->pm_FATsecs);
449 		pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
450 				       + DEV_BSIZE - 1)
451 			/ DEV_BSIZE; /* in blocks */
452 		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
453 	}
454 
455 	pmp->pm_maxcluster = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
456 	    SecPerClust + 1;
457 	pmp->pm_fatsize = pmp->pm_FATsecs * DEV_BSIZE; /* XXX not used? */
458 
459 	if (pmp->pm_fatmask == 0) {
460 		if (pmp->pm_maxcluster
461 		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
462 			/*
463 			 * This will usually be a floppy disk. This size makes
464 			 * sure that one fat entry will not be split across
465 			 * multiple blocks.
466 			 */
467 			pmp->pm_fatmask = FAT12_MASK;
468 			pmp->pm_fatmult = 3;
469 			pmp->pm_fatdiv = 2;
470 		} else {
471 			pmp->pm_fatmask = FAT16_MASK;
472 			pmp->pm_fatmult = 2;
473 			pmp->pm_fatdiv = 1;
474 		}
475 	}
476 
477 	clusters = (pmp->pm_fatsize / pmp->pm_fatmult) * pmp->pm_fatdiv;
478 	if (pmp->pm_maxcluster >= clusters) {
479 		kprintf("Warning: number of clusters (%ld) exceeds FAT "
480 		    "capacity (%ld)\n", pmp->pm_maxcluster + 1, clusters);
481 		pmp->pm_maxcluster = clusters - 1;
482 	}
483 
484 
485 	if (FAT12(pmp))
486 		pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
487 	else
488 		pmp->pm_fatblocksize = MSDOSFS_DFLTBSIZE;
489 
490 	pmp->pm_fatblocksec = pmp->pm_fatblocksize / DEV_BSIZE;
491 	pmp->pm_bnshift = DEV_BSHIFT;
492 
493 	/*
494 	 * Compute mask and shift value for isolating cluster relative byte
495 	 * offsets and cluster numbers from a file offset.
496 	 */
497 	pmp->pm_bpcluster = SecPerClust * DEV_BSIZE;
498 	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
499 	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;
500 
501 	/*
502 	 * Check for valid cluster size
503 	 * must be a power of 2
504 	 */
505 	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
506 		error = EINVAL;
507 		goto error_exit;
508 	}
509 
510 	/*
511 	 * Release the bootsector buffer.
512 	 */
513 	brelse(bp);
514 	bp = NULL;
515 
516 	/*
517 	 * Check FSInfo.
518 	 */
519 	if (pmp->pm_fsinfo) {
520 		struct fsinfo *fp;
521 
522 		if ((error = bread(devvp, de_bntodoff(pmp, pmp->pm_fsinfo), fsi_size(pmp), &bp)) != 0)
523 			goto error_exit;
524 		fp = (struct fsinfo *)bp->b_data;
525 		if (!bcmp(fp->fsisig1, "RRaA", 4)
526 		    && !bcmp(fp->fsisig2, "rrAa", 4)
527 		    && !bcmp(fp->fsisig3, "\0\0\125\252", 4)
528 		    && !bcmp(fp->fsisig4, "\0\0\125\252", 4)) {
529 			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
530 			if (pmp->pm_nxtfree == 0xffffffff)
531 				pmp->pm_nxtfree = CLUST_FIRST;
532 		} else
533 			pmp->pm_fsinfo = 0;
534 		brelse(bp);
535 		bp = NULL;
536 	}
537 
538 	/*
539 	 * Check and validate (or perhaps invalidate?) the fsinfo structure?
540 	 */
541 	if (pmp->pm_fsinfo && pmp->pm_nxtfree > pmp->pm_maxcluster) {
542 		kprintf(
543 		"Next free cluster in FSInfo (%lu) exceeds maxcluster (%lu)\n",
544 		    pmp->pm_nxtfree, pmp->pm_maxcluster);
545 		error = EINVAL;
546 		goto error_exit;
547 	}
548 
549 	/*
550 	 * Allocate memory for the bitmap of allocated clusters, and then
551 	 * fill it in.
552 	 */
553 	pmp->pm_inusemap = kmalloc(((pmp->pm_maxcluster + N_INUSEBITS - 1)
554 				   / N_INUSEBITS)
555 				  * sizeof(*pmp->pm_inusemap),
556 				  M_MSDOSFSFAT, M_WAITOK);
557 
558 	/*
559 	 * fillinusemap() needs pm_devvp.
560 	 */
561 	pmp->pm_dev = dev;
562 	pmp->pm_devvp = devvp;
563 
564 	/*
565 	 * Have the inuse map filled in.
566 	 */
567 	if ((error = fillinusemap(pmp)) != 0)
568 		goto error_exit;
569 
570 	/*
571 	 * If they want fat updates to be synchronous then let them suffer
572 	 * the performance degradation in exchange for the on disk copy of
573 	 * the fat being correct just about all the time.  I suppose this
574 	 * would be a good thing to turn on if the kernel is still flakey.
575 	 */
576 	if (mp->mnt_flag & MNT_SYNCHRONOUS)
577 		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;
578 
579 	/*
580 	 * Finish up.
581 	 */
582 	if (ronly)
583 		pmp->pm_flags |= MSDOSFSMNT_RONLY;
584 	else
585 		pmp->pm_fmod = 1;
586 	mp->mnt_data = (qaddr_t) pmp;
587 	mp->mnt_stat.f_fsid.val[0] = dev2udev(dev);
588 	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
589 	mp->mnt_flag |= MNT_LOCAL;
590 	vfs_add_vnodeops(mp, &msdosfs_vnode_vops, &mp->mnt_vn_norm_ops);
591 	dev->si_mountpoint = mp;
592 
593 	return 0;
594 
595 error_exit:
596 	if (bp)
597 		brelse(bp);
598 	VOP_CLOSE(devvp, ronly ? FREAD : FREAD | FWRITE);
599 	if (pmp) {
600 		if (pmp->pm_inusemap)
601 			kfree(pmp->pm_inusemap, M_MSDOSFSFAT);
602 		kfree(pmp, M_MSDOSFSMNT);
603 		mp->mnt_data = (qaddr_t)0;
604 	}
605 	return (error);
606 }
607 
608 /*
609  * Unmount the filesystem described by mp.
610  */
611 static int
612 msdosfs_unmount(struct mount *mp, int mntflags)
613 {
614 	struct msdosfsmount *pmp;
615 	int error, flags;
616 
617 	flags = 0;
618 	if (mntflags & MNT_FORCE)
619 		flags |= FORCECLOSE;
620 	error = vflush(mp, 0, flags);
621 	if (error)
622 		return error;
623 	pmp = VFSTOMSDOSFS(mp);
624 	pmp->pm_devvp->v_rdev->si_mountpoint = NULL;
625 #ifdef MSDOSFS_DEBUG
626 	{
627 		struct vnode *vp = pmp->pm_devvp;
628 
629 		kprintf("msdosfs_umount(): just before calling VOP_CLOSE()\n");
630 		kprintf("flag %08x, sysrefs %d, writecount %d, auxrefs %d\n",
631 		    vp->v_flag, vp->v_sysref.refcnt,
632 		    vp->v_writecount, vp->v_auxrefs);
633 		kprintf("mount %p, op %p\n", vp->v_mount, vp->v_ops);
634 		kprintf("mount %p\n", vp->v_mount);
635 		kprintf("cleanblkhd %p, dirtyblkhd %p, numoutput %d, type %d\n",
636 		    RB_ROOT(&vp->v_rbclean_tree),
637 		    RB_ROOT(&vp->v_rbdirty_tree),
638 		    vp->v_track_write.bk_active, vp->v_type);
639 		kprintf("union %p, tag %d, data[0] %08x, data[1] %08x\n",
640 		    vp->v_socket, vp->v_tag,
641 		    ((u_int *)vp->v_data)[0],
642 		    ((u_int *)vp->v_data)[1]);
643 	}
644 #endif
645 	error = VOP_CLOSE(pmp->pm_devvp,
646 		    (pmp->pm_flags&MSDOSFSMNT_RONLY) ? FREAD : FREAD | FWRITE);
647 	vrele(pmp->pm_devvp);
648 	kfree(pmp->pm_inusemap, M_MSDOSFSFAT);
649 	kfree(pmp, M_MSDOSFSMNT);
650 	mp->mnt_data = (qaddr_t)0;
651 	mp->mnt_flag &= ~MNT_LOCAL;
652 	return (error);
653 }
654 
655 static int
656 msdosfs_root(struct mount *mp, struct vnode **vpp)
657 {
658 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
659 	struct denode *ndep;
660 	int error;
661 
662 #ifdef MSDOSFS_DEBUG
663 	kprintf("msdosfs_root(); mp %p, pmp %p\n", mp, pmp);
664 #endif
665 	error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, &ndep);
666 	if (error)
667 		return (error);
668 	*vpp = DETOV(ndep);
669 	return (0);
670 }
671 
672 static int
673 msdosfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
674 {
675 	struct msdosfsmount *pmp;
676 
677 	pmp = VFSTOMSDOSFS(mp);
678 	sbp->f_bsize = pmp->pm_bpcluster;
679 	sbp->f_iosize = pmp->pm_bpcluster;
680 	sbp->f_blocks = pmp->pm_maxcluster + 1;
681 	sbp->f_bfree = pmp->pm_freeclustercount;
682 	sbp->f_bavail = pmp->pm_freeclustercount;
683 	sbp->f_files = pmp->pm_RootDirEnts;			/* XXX */
684 	sbp->f_ffree = 0;	/* what to put in here? */
685 	if (sbp != &mp->mnt_stat) {
686 		sbp->f_type = mp->mnt_vfc->vfc_typenum;
687 		bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
688 	}
689 	strncpy(sbp->f_fstypename, mp->mnt_vfc->vfc_name, MFSNAMELEN);
690 	return (0);
691 }
692 
693 struct scaninfo {
694 	int rescan;
695 	int allerror;
696 	int waitfor;
697 };
698 
699 static int msdosfs_sync_scan(struct mount *mp, struct vnode *vp, void *data);
700 
701 static int
702 msdosfs_sync(struct mount *mp, int waitfor)
703 {
704 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
705 	struct scaninfo scaninfo;
706 	int error;
707 
708 	/*
709 	 * If we ever switch to not updating all of the fats all the time,
710 	 * this would be the place to update them from the first one.
711 	 */
712 	if (pmp->pm_fmod != 0) {
713 		if (pmp->pm_flags & MSDOSFSMNT_RONLY)
714 			panic("msdosfs_sync: rofs mod");
715 		else {
716 			/* update fats here */
717 		}
718 	}
719 	/*
720 	 * Write back each (modified) denode.
721 	 */
722 	scaninfo.allerror = 0;
723 	scaninfo.rescan = 1;
724 	while (scaninfo.rescan) {
725 		scaninfo.rescan = 0;
726 		vmntvnodescan(mp, VMSC_GETVP|VMSC_NOWAIT, NULL, msdosfs_sync_scan, &scaninfo);
727 	}
728 
729 	/*
730 	 * Flush filesystem control info.
731 	 */
732 	if (waitfor != MNT_LAZY) {
733 		vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY);
734 		if ((error = VOP_FSYNC(pmp->pm_devvp, waitfor)) != 0)
735 			scaninfo.allerror = error;
736 		vn_unlock(pmp->pm_devvp);
737 	}
738 	return (scaninfo.allerror);
739 }
740 
741 static int
742 msdosfs_sync_scan(struct mount *mp, struct vnode *vp, void *data)
743 {
744 	struct scaninfo *info = data;
745 	struct denode *dep;
746 	int error;
747 
748 	dep = VTODE(vp);
749 	if (vp->v_type == VNON || vp->v_type == VBAD ||
750 	    ((dep->de_flag &
751 	    (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0 &&
752 	    (RB_EMPTY(&vp->v_rbdirty_tree) || info->waitfor == MNT_LAZY))) {
753 		return(0);
754 	}
755 	if ((error = VOP_FSYNC(vp, info->waitfor)) != 0)
756 		info->allerror = error;
757 	return(0);
758 }
759 
760 static int
761 msdosfs_fhtovp(struct mount *mp, struct vnode *rootvp,
762 	       struct fid *fhp, struct vnode **vpp)
763 {
764 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
765 	struct defid *defhp = (struct defid *) fhp;
766 	struct denode *dep;
767 	int error;
768 
769 	error = deget(pmp, defhp->defid_dirclust, defhp->defid_dirofs, &dep);
770 	if (error) {
771 		*vpp = NULLVP;
772 		return (error);
773 	}
774 	*vpp = DETOV(dep);
775 	return (0);
776 }
777 
778 static int
779 msdosfs_checkexp(struct mount *mp, struct sockaddr *nam, int *exflagsp,
780 		 struct ucred **credanonp)
781 {
782 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
783 	struct netcred *np;
784 
785 	np = vfs_export_lookup(mp, &pmp->pm_export, nam);
786 	if (np == NULL)
787 		return (EACCES);
788 	*exflagsp = np->netc_exflags;
789 	*credanonp = &np->netc_anon;
790 	return (0);
791 }
792 
793 static int
794 msdosfs_vptofh(struct vnode *vp, struct fid *fhp)
795 {
796 	struct denode *dep;
797 	struct defid *defhp;
798 
799 	dep = VTODE(vp);
800 	defhp = (struct defid *)fhp;
801 	defhp->defid_len = sizeof(struct defid);
802 	defhp->defid_dirclust = dep->de_dirclust;
803 	defhp->defid_dirofs = dep->de_diroffset;
804 	/* defhp->defid_gen = dep->de_gen; */
805 	return (0);
806 }
807 
808 static struct vfsops msdosfs_vfsops = {
809 	.vfs_mount =     	msdosfs_mount,
810 	.vfs_unmount =   	msdosfs_unmount,
811 	.vfs_root =     	msdosfs_root,
812 	.vfs_statfs =   	msdosfs_statfs,
813 	.vfs_sync =     	msdosfs_sync,
814 	.vfs_fhtovp =   	msdosfs_fhtovp,
815 	.vfs_checkexp =  	msdosfs_checkexp,
816 	.vfs_vptofh =   	msdosfs_vptofh,
817 	.vfs_init =     	msdosfs_init,
818 	.vfs_uninit =   	msdosfs_uninit
819 };
820 
821 VFS_SET(msdosfs_vfsops, msdos, 0);
822