xref: /dragonfly/sys/vfs/msdosfs/msdosfs_vfsops.c (revision b7367ef6)
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 1.48 2007/08/07 20:05:30 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 fid *,
95 				    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 #ifndef __DragonFly__
128 	/*
129 	 * GEMDOS knows nothing (yet) about win95
130 	 */
131 	if (pmp->pm_flags & MSDOSFSMNT_GEMDOSFS)
132 		pmp->pm_flags |= MSDOSFSMNT_NOWIN95;
133 #endif
134 
135 	if (pmp->pm_flags & MSDOSFSMNT_NOWIN95)
136 		pmp->pm_flags |= MSDOSFSMNT_SHORTNAME;
137 	else if (!(pmp->pm_flags &
138 	    (MSDOSFSMNT_SHORTNAME | MSDOSFSMNT_LONGNAME))) {
139 		struct vnode *rootvp;
140 
141 		/*
142 		 * Try to divine whether to support Win'95 long filenames
143 		 */
144 		if (FAT32(pmp))
145 			pmp->pm_flags |= MSDOSFSMNT_LONGNAME;
146 		else {
147 			if ((error = msdosfs_root(mp, &rootvp)) != 0)
148 				return error;
149 			pmp->pm_flags |= findwin95(VTODE(rootvp))
150 				? MSDOSFSMNT_LONGNAME
151 					: MSDOSFSMNT_SHORTNAME;
152 			vput(rootvp);
153 		}
154 	}
155 	return 0;
156 }
157 
158 /*
159  * mp - path - addr in user space of mount point (ie /usr or whatever)
160  * data - addr in user space of mount params including the name of the block
161  * special file to treat as a filesystem.
162  */
163 static int
164 msdosfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred)
165 {
166 	struct vnode *devvp;	  /* vnode for blk device to mount */
167 	struct msdosfs_args args; /* will hold data from mount request */
168 	/* msdosfs specific mount control block */
169 	struct msdosfsmount *pmp = NULL;
170 	size_t size;
171 	int error, flags;
172 	mode_t accessmode;
173 	struct nlookupdata nd;
174 
175 	error = copyin(data, (caddr_t)&args, sizeof(struct msdosfs_args));
176 	if (error)
177 		return (error);
178 	if (args.magic != MSDOSFS_ARGSMAGIC)
179 		args.flags = 0;
180 	/*
181 	 * If updating, check whether changing from read-only to
182 	 * read/write; if there is no device name, that's all we do.
183 	 */
184 	if (mp->mnt_flag & MNT_UPDATE) {
185 		pmp = VFSTOMSDOSFS(mp);
186 		error = 0;
187 		if (!(pmp->pm_flags & MSDOSFSMNT_RONLY) && (mp->mnt_flag & MNT_RDONLY)) {
188 			flags = WRITECLOSE;
189 			if (mp->mnt_flag & MNT_FORCE)
190 				flags |= FORCECLOSE;
191 			error = vflush(mp, 0, flags);
192 		}
193 		if (!error && (mp->mnt_flag & MNT_RELOAD))
194 			/* not yet implemented */
195 			error = EOPNOTSUPP;
196 		if (error)
197 			return (error);
198 		if ((pmp->pm_flags & MSDOSFSMNT_RONLY) && (mp->mnt_kern_flag & MNTK_WANTRDWR)) {
199 			/*
200 			 * If upgrade to read-write by non-root, then verify
201 			 * that user has necessary permissions on the device.
202 			 */
203 			if (cred->cr_uid != 0) {
204 				devvp = pmp->pm_devvp;
205 				vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
206 				error = VOP_ACCESS(devvp, VREAD | VWRITE, cred);
207 				if (error) {
208 					vn_unlock(devvp);
209 					return (error);
210 				}
211 				vn_unlock(devvp);
212 			}
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 __DragonFly__
351 	if (!(argp->flags & MSDOSFSMNT_GEMDOSFS)) {
352 #endif
353 #ifndef MSDOSFS_NOCHECKSIG
354 		if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
355 		    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
356 			error = EINVAL;
357 			goto error_exit;
358 		}
359 #endif
360 #ifndef __DragonFly__
361 	}
362 #endif
363 
364 	pmp = kmalloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK);
365 	bzero((caddr_t)pmp, sizeof *pmp);
366 	pmp->pm_mountp = mp;
367 
368 	/*
369 	 * Compute several useful quantities from the bpb in the
370 	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
371 	 * the fields that are different between dos 5 and dos 3.3.
372 	 */
373 	SecPerClust = b50->bpbSecPerClust;
374 	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
375 	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
376 	pmp->pm_FATs = b50->bpbFATs;
377 	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
378 	pmp->pm_Sectors = getushort(b50->bpbSectors);
379 	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
380 	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
381 	pmp->pm_Heads = getushort(b50->bpbHeads);
382 	pmp->pm_Media = b50->bpbMedia;
383 
384 	/* calculate the ratio of sector size to DEV_BSIZE */
385 	pmp->pm_BlkPerSec = pmp->pm_BytesPerSec / DEV_BSIZE;
386 
387 #ifndef __DragonFly__
388 	if (!(argp->flags & MSDOSFSMNT_GEMDOSFS)) {
389 #endif
390 		/* XXX - We should probably check more values here */
391 		if (!pmp->pm_BytesPerSec || !SecPerClust
392 			|| !pmp->pm_Heads
393 			|| !pmp->pm_SecPerTrack || pmp->pm_SecPerTrack > 63) {
394 			error = EINVAL;
395 			goto error_exit;
396 		}
397 #ifndef __DragonFly__
398 	}
399 #endif
400 
401 	if (pmp->pm_Sectors == 0) {
402 		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
403 		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
404 	} else {
405 		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
406 		pmp->pm_HugeSectors = pmp->pm_Sectors;
407 	}
408 
409 	if (pmp->pm_RootDirEnts == 0) {
410 		if (bsp->bs710.bsBootSectSig2 != BOOTSIG2
411 		    || bsp->bs710.bsBootSectSig3 != BOOTSIG3
412 		    || pmp->pm_Sectors
413 		    || pmp->pm_FATsecs
414 		    || getushort(b710->bpbFSVers)) {
415 			error = EINVAL;
416 			kprintf("mountmsdosfs(): bad FAT32 filesystem\n");
417 			goto error_exit;
418 		}
419 		pmp->pm_fatmask = FAT32_MASK;
420 		pmp->pm_fatmult = 4;
421 		pmp->pm_fatdiv = 1;
422 		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);
423 		if (getushort(b710->bpbExtFlags) & FATMIRROR)
424 			pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
425 		else
426 			pmp->pm_flags |= MSDOSFS_FATMIRROR;
427 	} else
428 		pmp->pm_flags |= MSDOSFS_FATMIRROR;
429 
430 	/*
431 	 * Check a few values (could do some more):
432 	 * - logical sector size: power of 2, >= block size
433 	 * - sectors per cluster: power of 2, >= 1
434 	 * - number of sectors:   >= 1, <= size of partition
435 	 */
436 	if ( (SecPerClust == 0)
437 	  || (SecPerClust & (SecPerClust - 1))
438 	  || (pmp->pm_BytesPerSec < DEV_BSIZE)
439 	  || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
440 	  || (pmp->pm_HugeSectors == 0)
441 	) {
442 		error = EINVAL;
443 		goto error_exit;
444 	}
445 
446 	pmp->pm_HugeSectors *= pmp->pm_BlkPerSec;
447 	pmp->pm_HiddenSects *= pmp->pm_BlkPerSec; /* XXX not used? */
448 	pmp->pm_FATsecs     *= pmp->pm_BlkPerSec;
449 	SecPerClust         *= pmp->pm_BlkPerSec;
450 
451 	pmp->pm_fatblk = pmp->pm_ResSectors * pmp->pm_BlkPerSec;
452 
453 	if (FAT32(pmp)) {
454 		pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
455 		pmp->pm_firstcluster = pmp->pm_fatblk
456 			+ (pmp->pm_FATs * pmp->pm_FATsecs);
457 		pmp->pm_fsinfo = getushort(b710->bpbFSInfo) * pmp->pm_BlkPerSec;
458 	} else {
459 		pmp->pm_rootdirblk = pmp->pm_fatblk +
460 			(pmp->pm_FATs * pmp->pm_FATsecs);
461 		pmp->pm_rootdirsize = (pmp->pm_RootDirEnts * sizeof(struct direntry)
462 				       + DEV_BSIZE - 1)
463 			/ DEV_BSIZE; /* in blocks */
464 		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
465 	}
466 
467 	pmp->pm_maxcluster = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
468 	    SecPerClust + 1;
469 	pmp->pm_fatsize = pmp->pm_FATsecs * DEV_BSIZE; /* XXX not used? */
470 
471 #ifndef __DragonFly__
472 	if (argp->flags & MSDOSFSMNT_GEMDOSFS) {
473 		if ((pmp->pm_maxcluster <= (0xff0 - 2))
474 		      && ((dtype == DTYPE_FLOPPY) || ((dtype == DTYPE_VNODE)
475 		      && ((pmp->pm_Heads == 1) || (pmp->pm_Heads == 2))))
476 		    ) {
477 			pmp->pm_fatmask = FAT12_MASK;
478 			pmp->pm_fatmult = 3;
479 			pmp->pm_fatdiv = 2;
480 		} else {
481 			pmp->pm_fatmask = FAT16_MASK;
482 			pmp->pm_fatmult = 2;
483 			pmp->pm_fatdiv = 1;
484 		}
485 	} else
486 #endif
487 	if (pmp->pm_fatmask == 0) {
488 		if (pmp->pm_maxcluster
489 		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
490 			/*
491 			 * This will usually be a floppy disk. This size makes
492 			 * sure that one fat entry will not be split across
493 			 * multiple blocks.
494 			 */
495 			pmp->pm_fatmask = FAT12_MASK;
496 			pmp->pm_fatmult = 3;
497 			pmp->pm_fatdiv = 2;
498 		} else {
499 			pmp->pm_fatmask = FAT16_MASK;
500 			pmp->pm_fatmult = 2;
501 			pmp->pm_fatdiv = 1;
502 		}
503 	}
504 
505 	clusters = (pmp->pm_fatsize / pmp->pm_fatmult) * pmp->pm_fatdiv;
506 	if (pmp->pm_maxcluster >= clusters) {
507 		kprintf("Warning: number of clusters (%ld) exceeds FAT "
508 		    "capacity (%ld)\n", pmp->pm_maxcluster + 1, clusters);
509 		pmp->pm_maxcluster = clusters - 1;
510 	}
511 
512 
513 	if (FAT12(pmp))
514 		pmp->pm_fatblocksize = 3 * pmp->pm_BytesPerSec;
515 	else
516 		pmp->pm_fatblocksize = MSDOSFS_DFLTBSIZE;
517 
518 	pmp->pm_fatblocksec = pmp->pm_fatblocksize / DEV_BSIZE;
519 	pmp->pm_bnshift = DEV_BSHIFT;
520 
521 	/*
522 	 * Compute mask and shift value for isolating cluster relative byte
523 	 * offsets and cluster numbers from a file offset.
524 	 */
525 	pmp->pm_bpcluster = SecPerClust * DEV_BSIZE;
526 	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
527 	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;
528 
529 	/*
530 	 * Check for valid cluster size
531 	 * must be a power of 2
532 	 */
533 	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
534 		error = EINVAL;
535 		goto error_exit;
536 	}
537 
538 	/*
539 	 * Release the bootsector buffer.
540 	 */
541 	brelse(bp);
542 	bp = NULL;
543 
544 	/*
545 	 * Check FSInfo.
546 	 */
547 	if (pmp->pm_fsinfo) {
548 		struct fsinfo *fp;
549 
550 		if ((error = bread(devvp, de_bntodoff(pmp, pmp->pm_fsinfo), fsi_size(pmp), &bp)) != 0)
551 			goto error_exit;
552 		fp = (struct fsinfo *)bp->b_data;
553 		if (!bcmp(fp->fsisig1, "RRaA", 4)
554 		    && !bcmp(fp->fsisig2, "rrAa", 4)
555 		    && !bcmp(fp->fsisig3, "\0\0\125\252", 4)
556 		    && !bcmp(fp->fsisig4, "\0\0\125\252", 4)) {
557 			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
558 			if (pmp->pm_nxtfree == 0xffffffff)
559 				pmp->pm_nxtfree = CLUST_FIRST;
560 		} else
561 			pmp->pm_fsinfo = 0;
562 		brelse(bp);
563 		bp = NULL;
564 	}
565 
566 	/*
567 	 * Check and validate (or perhaps invalidate?) the fsinfo structure?
568 	 */
569 	if (pmp->pm_fsinfo && pmp->pm_nxtfree > pmp->pm_maxcluster) {
570 		kprintf(
571 		"Next free cluster in FSInfo (%lu) exceeds maxcluster (%lu)\n",
572 		    pmp->pm_nxtfree, pmp->pm_maxcluster);
573 		error = EINVAL;
574 		goto error_exit;
575 	}
576 
577 	/*
578 	 * Allocate memory for the bitmap of allocated clusters, and then
579 	 * fill it in.
580 	 */
581 	pmp->pm_inusemap = kmalloc(((pmp->pm_maxcluster + N_INUSEBITS - 1)
582 				   / N_INUSEBITS)
583 				  * sizeof(*pmp->pm_inusemap),
584 				  M_MSDOSFSFAT, M_WAITOK);
585 
586 	/*
587 	 * fillinusemap() needs pm_devvp.
588 	 */
589 	pmp->pm_dev = dev;
590 	pmp->pm_devvp = devvp;
591 
592 	/*
593 	 * Have the inuse map filled in.
594 	 */
595 	if ((error = fillinusemap(pmp)) != 0)
596 		goto error_exit;
597 
598 	/*
599 	 * If they want fat updates to be synchronous then let them suffer
600 	 * the performance degradation in exchange for the on disk copy of
601 	 * the fat being correct just about all the time.  I suppose this
602 	 * would be a good thing to turn on if the kernel is still flakey.
603 	 */
604 	if (mp->mnt_flag & MNT_SYNCHRONOUS)
605 		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;
606 
607 	/*
608 	 * Finish up.
609 	 */
610 	if (ronly)
611 		pmp->pm_flags |= MSDOSFSMNT_RONLY;
612 	else
613 		pmp->pm_fmod = 1;
614 	mp->mnt_data = (qaddr_t) pmp;
615 	mp->mnt_stat.f_fsid.val[0] = dev2udev(dev);
616 	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
617 	mp->mnt_flag |= MNT_LOCAL;
618 	vfs_add_vnodeops(mp, &msdosfs_vnode_vops, &mp->mnt_vn_norm_ops);
619 	dev->si_mountpoint = mp;
620 
621 	return 0;
622 
623 error_exit:
624 	if (bp)
625 		brelse(bp);
626 	VOP_CLOSE(devvp, ronly ? FREAD : FREAD | FWRITE);
627 	if (pmp) {
628 		if (pmp->pm_inusemap)
629 			kfree(pmp->pm_inusemap, M_MSDOSFSFAT);
630 		kfree(pmp, M_MSDOSFSMNT);
631 		mp->mnt_data = (qaddr_t)0;
632 	}
633 	return (error);
634 }
635 
636 /*
637  * Unmount the filesystem described by mp.
638  */
639 static int
640 msdosfs_unmount(struct mount *mp, int mntflags)
641 {
642 	struct msdosfsmount *pmp;
643 	int error, flags;
644 
645 	flags = 0;
646 	if (mntflags & MNT_FORCE)
647 		flags |= FORCECLOSE;
648 	error = vflush(mp, 0, flags);
649 	if (error)
650 		return error;
651 	pmp = VFSTOMSDOSFS(mp);
652 	pmp->pm_devvp->v_rdev->si_mountpoint = NULL;
653 #ifdef MSDOSFS_DEBUG
654 	{
655 		struct vnode *vp = pmp->pm_devvp;
656 
657 		kprintf("msdosfs_umount(): just before calling VOP_CLOSE()\n");
658 		kprintf("flag %08x, sysrefs %d, writecount %d, auxrefs %d\n",
659 		    vp->v_flag, vp->v_sysref.refcnt,
660 		    vp->v_writecount, vp->v_auxrefs);
661 		kprintf("mount %p, op %p\n", vp->v_mount, vp->v_ops);
662 		kprintf("freef %p, freeb %p, mount %p\n",
663 		    TAILQ_NEXT(vp, v_freelist),
664 		    *vp->v_freelist.tqe_prev,
665 		    vp->v_mount);
666 		kprintf("cleanblkhd %p, dirtyblkhd %p, numoutput %d, type %d\n",
667 		    RB_ROOT(&vp->v_rbclean_tree),
668 		    RB_ROOT(&vp->v_rbdirty_tree),
669 		    vp->v_track_write.bk_active, vp->v_type);
670 		kprintf("union %p, tag %d, data[0] %08x, data[1] %08x\n",
671 		    vp->v_socket, vp->v_tag,
672 		    ((u_int *)vp->v_data)[0],
673 		    ((u_int *)vp->v_data)[1]);
674 	}
675 #endif
676 	error = VOP_CLOSE(pmp->pm_devvp,
677 		    (pmp->pm_flags&MSDOSFSMNT_RONLY) ? FREAD : FREAD | FWRITE);
678 	vrele(pmp->pm_devvp);
679 	kfree(pmp->pm_inusemap, M_MSDOSFSFAT);
680 	kfree(pmp, M_MSDOSFSMNT);
681 	mp->mnt_data = (qaddr_t)0;
682 	mp->mnt_flag &= ~MNT_LOCAL;
683 	return (error);
684 }
685 
686 static int
687 msdosfs_root(struct mount *mp, struct vnode **vpp)
688 {
689 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
690 	struct denode *ndep;
691 	int error;
692 
693 #ifdef MSDOSFS_DEBUG
694 	kprintf("msdosfs_root(); mp %p, pmp %p\n", mp, pmp);
695 #endif
696 	error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, &ndep);
697 	if (error)
698 		return (error);
699 	*vpp = DETOV(ndep);
700 	return (0);
701 }
702 
703 static int
704 msdosfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
705 {
706 	struct msdosfsmount *pmp;
707 
708 	pmp = VFSTOMSDOSFS(mp);
709 	sbp->f_bsize = pmp->pm_bpcluster;
710 	sbp->f_iosize = pmp->pm_bpcluster;
711 	sbp->f_blocks = pmp->pm_maxcluster + 1;
712 	sbp->f_bfree = pmp->pm_freeclustercount;
713 	sbp->f_bavail = pmp->pm_freeclustercount;
714 	sbp->f_files = pmp->pm_RootDirEnts;			/* XXX */
715 	sbp->f_ffree = 0;	/* what to put in here? */
716 	if (sbp != &mp->mnt_stat) {
717 		sbp->f_type = mp->mnt_vfc->vfc_typenum;
718 		bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
719 	}
720 	strncpy(sbp->f_fstypename, mp->mnt_vfc->vfc_name, MFSNAMELEN);
721 	return (0);
722 }
723 
724 struct scaninfo {
725 	int rescan;
726 	int allerror;
727 	int waitfor;
728 };
729 
730 static int msdosfs_sync_scan(struct mount *mp, struct vnode *vp, void *data);
731 
732 static int
733 msdosfs_sync(struct mount *mp, int waitfor)
734 {
735 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
736 	struct scaninfo scaninfo;
737 	int error;
738 
739 	/*
740 	 * If we ever switch to not updating all of the fats all the time,
741 	 * this would be the place to update them from the first one.
742 	 */
743 	if (pmp->pm_fmod != 0) {
744 		if (pmp->pm_flags & MSDOSFSMNT_RONLY)
745 			panic("msdosfs_sync: rofs mod");
746 		else {
747 			/* update fats here */
748 		}
749 	}
750 	/*
751 	 * Write back each (modified) denode.
752 	 */
753 	scaninfo.allerror = 0;
754 	scaninfo.rescan = 1;
755 	while (scaninfo.rescan) {
756 		scaninfo.rescan = 0;
757 		vmntvnodescan(mp, VMSC_GETVP|VMSC_NOWAIT, NULL, msdosfs_sync_scan, &scaninfo);
758 	}
759 
760 	/*
761 	 * Flush filesystem control info.
762 	 */
763 	if (waitfor != MNT_LAZY) {
764 		vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY);
765 		if ((error = VOP_FSYNC(pmp->pm_devvp, waitfor)) != 0)
766 			scaninfo.allerror = error;
767 		vn_unlock(pmp->pm_devvp);
768 	}
769 	return (scaninfo.allerror);
770 }
771 
772 static int
773 msdosfs_sync_scan(struct mount *mp, struct vnode *vp, void *data)
774 {
775 	struct scaninfo *info = data;
776 	struct denode *dep;
777 	int error;
778 
779 	dep = VTODE(vp);
780 	if (vp->v_type == VNON || vp->v_type == VBAD ||
781 	    ((dep->de_flag &
782 	    (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0 &&
783 	    (RB_EMPTY(&vp->v_rbdirty_tree) || info->waitfor == MNT_LAZY))) {
784 		return(0);
785 	}
786 	if ((error = VOP_FSYNC(vp, info->waitfor)) != 0)
787 		info->allerror = error;
788 	return(0);
789 }
790 
791 static int
792 msdosfs_fhtovp(struct mount *mp, struct fid *fhp, struct vnode **vpp)
793 {
794 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
795 	struct defid *defhp = (struct defid *) fhp;
796 	struct denode *dep;
797 	int error;
798 
799 	error = deget(pmp, defhp->defid_dirclust, defhp->defid_dirofs, &dep);
800 	if (error) {
801 		*vpp = NULLVP;
802 		return (error);
803 	}
804 	*vpp = DETOV(dep);
805 	return (0);
806 }
807 
808 static int
809 msdosfs_checkexp(struct mount *mp, struct sockaddr *nam, int *exflagsp,
810 		 struct ucred **credanonp)
811 {
812 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
813 	struct netcred *np;
814 
815 	np = vfs_export_lookup(mp, &pmp->pm_export, nam);
816 	if (np == NULL)
817 		return (EACCES);
818 	*exflagsp = np->netc_exflags;
819 	*credanonp = &np->netc_anon;
820 	return (0);
821 }
822 
823 static int
824 msdosfs_vptofh(struct vnode *vp, struct fid *fhp)
825 {
826 	struct denode *dep;
827 	struct defid *defhp;
828 
829 	dep = VTODE(vp);
830 	defhp = (struct defid *)fhp;
831 	defhp->defid_len = sizeof(struct defid);
832 	defhp->defid_dirclust = dep->de_dirclust;
833 	defhp->defid_dirofs = dep->de_diroffset;
834 	/* defhp->defid_gen = dep->de_gen; */
835 	return (0);
836 }
837 
838 static struct vfsops msdosfs_vfsops = {
839 	.vfs_mount =     	msdosfs_mount,
840 	.vfs_unmount =   	msdosfs_unmount,
841 	.vfs_root =     	msdosfs_root,
842 	.vfs_statfs =   	msdosfs_statfs,
843 	.vfs_sync =     	msdosfs_sync,
844 	.vfs_fhtovp =   	msdosfs_fhtovp,
845 	.vfs_checkexp =  	msdosfs_checkexp,
846 	.vfs_vptofh =   	msdosfs_vptofh,
847 	.vfs_init =     	msdosfs_init,
848 	.vfs_uninit =   	msdosfs_uninit
849 };
850 
851 VFS_SET(msdosfs_vfsops, msdos, 0);
852