xref: /freebsd/sys/fs/msdosfs/msdosfs_vfsops.c (revision 3416500aef140042c64bc149cb1ec6620483bc44)
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", "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 (vfs_scanopt(mp->mnt_optnew, "gid", "%d", &v) == 1)
153 		pmp->pm_gid = v;
154 	if (vfs_scanopt(mp->mnt_optnew, "uid", "%d", &v) == 1)
155 		pmp->pm_uid = v;
156 	if (vfs_scanopt(mp->mnt_optnew, "mask", "%d", &v) == 1)
157 		pmp->pm_mask = v & ALLPERMS;
158 	if (vfs_scanopt(mp->mnt_optnew, "dirmask", "%d", &v) == 1)
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
179 		pmp->pm_flags |= MSDOSFSMNT_LONGNAME;
180 	return 0;
181 }
182 
183 static int
184 msdosfs_cmount(struct mntarg *ma, void *data, uint64_t flags)
185 {
186 	struct msdosfs_args args;
187 	struct export_args exp;
188 	int error;
189 
190 	if (data == NULL)
191 		return (EINVAL);
192 	error = copyin(data, &args, sizeof args);
193 	if (error)
194 		return (error);
195 	vfs_oexport_conv(&args.export, &exp);
196 
197 	ma = mount_argsu(ma, "from", args.fspec, MAXPATHLEN);
198 	ma = mount_arg(ma, "export", &exp, sizeof(exp));
199 	ma = mount_argf(ma, "uid", "%d", args.uid);
200 	ma = mount_argf(ma, "gid", "%d", args.gid);
201 	ma = mount_argf(ma, "mask", "%d", args.mask);
202 	ma = mount_argf(ma, "dirmask", "%d", args.dirmask);
203 
204 	ma = mount_argb(ma, args.flags & MSDOSFSMNT_SHORTNAME, "noshortname");
205 	ma = mount_argb(ma, args.flags & MSDOSFSMNT_LONGNAME, "nolongname");
206 	ma = mount_argb(ma, !(args.flags & MSDOSFSMNT_NOWIN95), "nowin95");
207 	ma = mount_argb(ma, args.flags & MSDOSFSMNT_KICONV, "nokiconv");
208 
209 	ma = mount_argsu(ma, "cs_win", args.cs_win, MAXCSLEN);
210 	ma = mount_argsu(ma, "cs_dos", args.cs_dos, MAXCSLEN);
211 	ma = mount_argsu(ma, "cs_local", args.cs_local, MAXCSLEN);
212 
213 	error = kernel_mount(ma, flags);
214 
215 	return (error);
216 }
217 
218 /*
219  * mp - path - addr in user space of mount point (ie /usr or whatever)
220  * data - addr in user space of mount params including the name of the block
221  * special file to treat as a filesystem.
222  */
223 static int
224 msdosfs_mount(struct mount *mp)
225 {
226 	struct vnode *devvp;	  /* vnode for blk device to mount */
227 	struct thread *td;
228 	/* msdosfs specific mount control block */
229 	struct msdosfsmount *pmp = NULL;
230 	struct nameidata ndp;
231 	int error, flags;
232 	accmode_t accmode;
233 	char *from;
234 
235 	td = curthread;
236 	if (vfs_filteropt(mp->mnt_optnew, msdosfs_opts))
237 		return (EINVAL);
238 
239 	/*
240 	 * If updating, check whether changing from read-only to
241 	 * read/write; if there is no device name, that's all we do.
242 	 */
243 	if (mp->mnt_flag & MNT_UPDATE) {
244 		pmp = VFSTOMSDOSFS(mp);
245 		if (!(pmp->pm_flags & MSDOSFSMNT_RONLY) &&
246 		    vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0)) {
247 			error = VFS_SYNC(mp, MNT_WAIT);
248 			if (error)
249 				return (error);
250 			flags = WRITECLOSE;
251 			if (mp->mnt_flag & MNT_FORCE)
252 				flags |= FORCECLOSE;
253 			error = vflush(mp, 0, flags, td);
254 			if (error)
255 				return (error);
256 
257 			/*
258 			 * Now the volume is clean.  Mark it so while the
259 			 * device is still rw.
260 			 */
261 			error = markvoldirty(pmp, 0);
262 			if (error) {
263 				(void)markvoldirty(pmp, 1);
264 				return (error);
265 			}
266 
267 			/* Downgrade the device from rw to ro. */
268 			g_topology_lock();
269 			error = g_access(pmp->pm_cp, 0, -1, 0);
270 			g_topology_unlock();
271 			if (error) {
272 				(void)markvoldirty(pmp, 1);
273 				return (error);
274 			}
275 
276 			/*
277 			 * Backing out after an error was painful in the
278 			 * above.  Now we are committed to succeeding.
279 			 */
280 			pmp->pm_fmod = 0;
281 			pmp->pm_flags |= MSDOSFSMNT_RONLY;
282 			MNT_ILOCK(mp);
283 			mp->mnt_flag |= MNT_RDONLY;
284 			MNT_IUNLOCK(mp);
285 		} else if ((pmp->pm_flags & MSDOSFSMNT_RONLY) &&
286 		    !vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0)) {
287 			/*
288 			 * If upgrade to read-write by non-root, then verify
289 			 * that user has necessary permissions on the device.
290 			 */
291 			devvp = pmp->pm_devvp;
292 			vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
293 			error = VOP_ACCESS(devvp, VREAD | VWRITE,
294 			    td->td_ucred, td);
295 			if (error)
296 				error = priv_check(td, PRIV_VFS_MOUNT_PERM);
297 			if (error) {
298 				VOP_UNLOCK(devvp, 0);
299 				return (error);
300 			}
301 			VOP_UNLOCK(devvp, 0);
302 			g_topology_lock();
303 			error = g_access(pmp->pm_cp, 0, 1, 0);
304 			g_topology_unlock();
305 			if (error)
306 				return (error);
307 
308 			pmp->pm_fmod = 1;
309 			pmp->pm_flags &= ~MSDOSFSMNT_RONLY;
310 			MNT_ILOCK(mp);
311 			mp->mnt_flag &= ~MNT_RDONLY;
312 			MNT_IUNLOCK(mp);
313 
314 			/* Now that the volume is modifiable, mark it dirty. */
315 			error = markvoldirty(pmp, 1);
316 			if (error)
317 				return (error);
318 		}
319 	}
320 	/*
321 	 * Not an update, or updating the name: look up the name
322 	 * and verify that it refers to a sensible disk device.
323 	 */
324 	if (vfs_getopt(mp->mnt_optnew, "from", (void **)&from, NULL))
325 		return (EINVAL);
326 	NDINIT(&ndp, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, from, td);
327 	error = namei(&ndp);
328 	if (error)
329 		return (error);
330 	devvp = ndp.ni_vp;
331 	NDFREE(&ndp, NDF_ONLY_PNBUF);
332 
333 	if (!vn_isdisk(devvp, &error)) {
334 		vput(devvp);
335 		return (error);
336 	}
337 	/*
338 	 * If mount by non-root, then verify that user has necessary
339 	 * permissions on the device.
340 	 */
341 	accmode = VREAD;
342 	if ((mp->mnt_flag & MNT_RDONLY) == 0)
343 		accmode |= VWRITE;
344 	error = VOP_ACCESS(devvp, accmode, td->td_ucred, td);
345 	if (error)
346 		error = priv_check(td, PRIV_VFS_MOUNT_PERM);
347 	if (error) {
348 		vput(devvp);
349 		return (error);
350 	}
351 	if ((mp->mnt_flag & MNT_UPDATE) == 0) {
352 		error = mountmsdosfs(devvp, mp);
353 #ifdef MSDOSFS_DEBUG		/* only needed for the printf below */
354 		pmp = VFSTOMSDOSFS(mp);
355 #endif
356 	} else {
357 		vput(devvp);
358 		if (devvp != pmp->pm_devvp)
359 			return (EINVAL);	/* XXX needs translation */
360 	}
361 	if (error) {
362 		vrele(devvp);
363 		return (error);
364 	}
365 
366 	error = update_mp(mp, td);
367 	if (error) {
368 		if ((mp->mnt_flag & MNT_UPDATE) == 0)
369 			msdosfs_unmount(mp, MNT_FORCE);
370 		return error;
371 	}
372 
373 	vfs_mountedfrom(mp, from);
374 #ifdef MSDOSFS_DEBUG
375 	printf("msdosfs_mount(): mp %p, pmp %p, inusemap %p\n", mp, pmp, pmp->pm_inusemap);
376 #endif
377 	return (0);
378 }
379 
380 static int
381 mountmsdosfs(struct vnode *devvp, struct mount *mp)
382 {
383 	struct msdosfsmount *pmp;
384 	struct buf *bp;
385 	struct cdev *dev;
386 	union bootsector *bsp;
387 	struct byte_bpb33 *b33;
388 	struct byte_bpb50 *b50;
389 	struct byte_bpb710 *b710;
390 	uint8_t SecPerClust;
391 	u_long clusters;
392 	int ronly, error;
393 	struct g_consumer *cp;
394 	struct bufobj *bo;
395 
396 	bp = NULL;		/* This and pmp both used in error_exit. */
397 	pmp = NULL;
398 	ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
399 
400 	dev = devvp->v_rdev;
401 	if (atomic_cmpset_acq_ptr((uintptr_t *)&dev->si_mountpt, 0,
402 	    (uintptr_t)mp) == 0) {
403 		VOP_UNLOCK(devvp, 0);
404 		return (EBUSY);
405 	}
406 	g_topology_lock();
407 	error = g_vfs_open(devvp, &cp, "msdosfs", ronly ? 0 : 1);
408 	g_topology_unlock();
409 	if (error != 0) {
410 		atomic_store_rel_ptr((uintptr_t *)&dev->si_mountpt, 0);
411 		VOP_UNLOCK(devvp, 0);
412 		return (error);
413 	}
414 	dev_ref(dev);
415 	VOP_UNLOCK(devvp, 0);
416 
417 	bo = &devvp->v_bufobj;
418 
419 	/*
420 	 * Read the boot sector of the filesystem, and then check the
421 	 * boot signature.  If not a dos boot sector then error out.
422 	 *
423 	 * NOTE: 8192 is a magic size that works for ffs.
424 	 */
425 	error = bread(devvp, 0, 8192, NOCRED, &bp);
426 	if (error)
427 		goto error_exit;
428 	bp->b_flags |= B_AGE;
429 	bsp = (union bootsector *)bp->b_data;
430 	b33 = (struct byte_bpb33 *)bsp->bs33.bsBPB;
431 	b50 = (struct byte_bpb50 *)bsp->bs50.bsBPB;
432 	b710 = (struct byte_bpb710 *)bsp->bs710.bsBPB;
433 
434 #ifndef MSDOSFS_NOCHECKSIG
435 	if (bsp->bs50.bsBootSectSig0 != BOOTSIG0
436 	    || bsp->bs50.bsBootSectSig1 != BOOTSIG1) {
437 		error = EINVAL;
438 		goto error_exit;
439 	}
440 #endif
441 
442 	pmp = malloc(sizeof *pmp, M_MSDOSFSMNT, M_WAITOK | M_ZERO);
443 	pmp->pm_mountp = mp;
444 	pmp->pm_cp = cp;
445 	pmp->pm_bo = bo;
446 
447 	lockinit(&pmp->pm_fatlock, 0, msdosfs_lock_msg, 0, 0);
448 
449 	/*
450 	 * Initialize ownerships and permissions, since nothing else will
451 	 * initialize them iff we are mounting root.
452 	 */
453 	pmp->pm_uid = UID_ROOT;
454 	pmp->pm_gid = GID_WHEEL;
455 	pmp->pm_mask = pmp->pm_dirmask = S_IXUSR | S_IXGRP | S_IXOTH |
456 	    S_IRUSR | S_IRGRP | S_IROTH | S_IWUSR;
457 
458 	/*
459 	 * Compute several useful quantities from the bpb in the
460 	 * bootsector.  Copy in the dos 5 variant of the bpb then fix up
461 	 * the fields that are different between dos 5 and dos 3.3.
462 	 */
463 	SecPerClust = b50->bpbSecPerClust;
464 	pmp->pm_BytesPerSec = getushort(b50->bpbBytesPerSec);
465 	if (pmp->pm_BytesPerSec < DEV_BSIZE) {
466 		error = EINVAL;
467 		goto error_exit;
468 	}
469 	pmp->pm_ResSectors = getushort(b50->bpbResSectors);
470 	pmp->pm_FATs = b50->bpbFATs;
471 	pmp->pm_RootDirEnts = getushort(b50->bpbRootDirEnts);
472 	pmp->pm_Sectors = getushort(b50->bpbSectors);
473 	pmp->pm_FATsecs = getushort(b50->bpbFATsecs);
474 	pmp->pm_SecPerTrack = getushort(b50->bpbSecPerTrack);
475 	pmp->pm_Heads = getushort(b50->bpbHeads);
476 	pmp->pm_Media = b50->bpbMedia;
477 
478 	/* calculate the ratio of sector size to DEV_BSIZE */
479 	pmp->pm_BlkPerSec = pmp->pm_BytesPerSec / DEV_BSIZE;
480 
481 	/*
482 	 * We don't check pm_Heads nor pm_SecPerTrack, because
483 	 * these may not be set for EFI file systems. We don't
484 	 * use these anyway, so we're unaffected if they are
485 	 * invalid.
486 	 */
487 	if (!pmp->pm_BytesPerSec || !SecPerClust) {
488 		error = EINVAL;
489 		goto error_exit;
490 	}
491 
492 	if (pmp->pm_Sectors == 0) {
493 		pmp->pm_HiddenSects = getulong(b50->bpbHiddenSecs);
494 		pmp->pm_HugeSectors = getulong(b50->bpbHugeSectors);
495 	} else {
496 		pmp->pm_HiddenSects = getushort(b33->bpbHiddenSecs);
497 		pmp->pm_HugeSectors = pmp->pm_Sectors;
498 	}
499 
500 	if (pmp->pm_RootDirEnts == 0) {
501 		if (pmp->pm_FATsecs
502 		    || getushort(b710->bpbFSVers)) {
503 			error = EINVAL;
504 #ifdef MSDOSFS_DEBUG
505 			printf("mountmsdosfs(): bad FAT32 filesystem\n");
506 #endif
507 			goto error_exit;
508 		}
509 		pmp->pm_fatmask = FAT32_MASK;
510 		pmp->pm_fatmult = 4;
511 		pmp->pm_fatdiv = 1;
512 		pmp->pm_FATsecs = getulong(b710->bpbBigFATsecs);
513 		if (getushort(b710->bpbExtFlags) & FATMIRROR)
514 			pmp->pm_curfat = getushort(b710->bpbExtFlags) & FATNUM;
515 		else
516 			pmp->pm_flags |= MSDOSFS_FATMIRROR;
517 	} else
518 		pmp->pm_flags |= MSDOSFS_FATMIRROR;
519 
520 	/*
521 	 * Check a few values (could do some more):
522 	 * - logical sector size: power of 2, >= block size
523 	 * - sectors per cluster: power of 2, >= 1
524 	 * - number of sectors:   >= 1, <= size of partition
525 	 * - number of FAT sectors: >= 1
526 	 */
527 	if ( (SecPerClust == 0)
528 	  || (SecPerClust & (SecPerClust - 1))
529 	  || (pmp->pm_BytesPerSec < DEV_BSIZE)
530 	  || (pmp->pm_BytesPerSec & (pmp->pm_BytesPerSec - 1))
531 	  || (pmp->pm_HugeSectors == 0)
532 	  || (pmp->pm_FATsecs == 0)
533 	  || (SecPerClust * pmp->pm_BlkPerSec > MAXBSIZE / DEV_BSIZE)
534 	) {
535 		error = EINVAL;
536 		goto error_exit;
537 	}
538 
539 	pmp->pm_HugeSectors *= pmp->pm_BlkPerSec;
540 	pmp->pm_HiddenSects *= pmp->pm_BlkPerSec;	/* XXX not used? */
541 	pmp->pm_FATsecs     *= pmp->pm_BlkPerSec;
542 	SecPerClust         *= pmp->pm_BlkPerSec;
543 
544 	pmp->pm_fatblk = pmp->pm_ResSectors * pmp->pm_BlkPerSec;
545 
546 	if (FAT32(pmp)) {
547 		pmp->pm_rootdirblk = getulong(b710->bpbRootClust);
548 		pmp->pm_firstcluster = pmp->pm_fatblk
549 			+ (pmp->pm_FATs * pmp->pm_FATsecs);
550 		pmp->pm_fsinfo = getushort(b710->bpbFSInfo) * pmp->pm_BlkPerSec;
551 	} else {
552 		pmp->pm_rootdirblk = pmp->pm_fatblk +
553 			(pmp->pm_FATs * pmp->pm_FATsecs);
554 		pmp->pm_rootdirsize = howmany(pmp->pm_RootDirEnts *
555 			sizeof(struct direntry), DEV_BSIZE); /* in blocks */
556 		pmp->pm_firstcluster = pmp->pm_rootdirblk + pmp->pm_rootdirsize;
557 	}
558 
559 	pmp->pm_maxcluster = (pmp->pm_HugeSectors - pmp->pm_firstcluster) /
560 	    SecPerClust + 1;
561 	pmp->pm_fatsize = pmp->pm_FATsecs * DEV_BSIZE;	/* XXX not used? */
562 
563 	if (pmp->pm_fatmask == 0) {
564 		if (pmp->pm_maxcluster
565 		    <= ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK)) {
566 			/*
567 			 * This will usually be a floppy disk. This size makes
568 			 * sure that one FAT entry will not be split across
569 			 * multiple blocks.
570 			 */
571 			pmp->pm_fatmask = FAT12_MASK;
572 			pmp->pm_fatmult = 3;
573 			pmp->pm_fatdiv = 2;
574 		} else {
575 			pmp->pm_fatmask = FAT16_MASK;
576 			pmp->pm_fatmult = 2;
577 			pmp->pm_fatdiv = 1;
578 		}
579 	}
580 
581 	clusters = (pmp->pm_fatsize / pmp->pm_fatmult) * pmp->pm_fatdiv;
582 	if (pmp->pm_maxcluster >= clusters) {
583 #ifdef MSDOSFS_DEBUG
584 		printf("Warning: number of clusters (%ld) exceeds FAT "
585 		    "capacity (%ld)\n", pmp->pm_maxcluster + 1, clusters);
586 #endif
587 		pmp->pm_maxcluster = clusters - 1;
588 	}
589 
590 	if (FAT12(pmp))
591 		pmp->pm_fatblocksize = 3 * 512;
592 	else
593 		pmp->pm_fatblocksize = PAGE_SIZE;
594 	pmp->pm_fatblocksize = roundup(pmp->pm_fatblocksize,
595 	    pmp->pm_BytesPerSec);
596 	pmp->pm_fatblocksec = pmp->pm_fatblocksize / DEV_BSIZE;
597 	pmp->pm_bnshift = ffs(DEV_BSIZE) - 1;
598 
599 	/*
600 	 * Compute mask and shift value for isolating cluster relative byte
601 	 * offsets and cluster numbers from a file offset.
602 	 */
603 	pmp->pm_bpcluster = SecPerClust * DEV_BSIZE;
604 	pmp->pm_crbomask = pmp->pm_bpcluster - 1;
605 	pmp->pm_cnshift = ffs(pmp->pm_bpcluster) - 1;
606 
607 	/*
608 	 * Check for valid cluster size
609 	 * must be a power of 2
610 	 */
611 	if (pmp->pm_bpcluster ^ (1 << pmp->pm_cnshift)) {
612 		error = EINVAL;
613 		goto error_exit;
614 	}
615 
616 	/*
617 	 * Release the bootsector buffer.
618 	 */
619 	brelse(bp);
620 	bp = NULL;
621 
622 	/*
623 	 * Check the fsinfo sector if we have one.  Silently fix up our
624 	 * in-core copy of fp->fsinxtfree if it is unknown (0xffffffff)
625 	 * or too large.  Ignore fp->fsinfree for now, since we need to
626 	 * read the entire FAT anyway to fill the inuse map.
627 	 */
628 	if (pmp->pm_fsinfo) {
629 		struct fsinfo *fp;
630 
631 		if ((error = bread(devvp, pmp->pm_fsinfo, pmp->pm_BytesPerSec,
632 		    NOCRED, &bp)) != 0)
633 			goto error_exit;
634 		fp = (struct fsinfo *)bp->b_data;
635 		if (!bcmp(fp->fsisig1, "RRaA", 4)
636 		    && !bcmp(fp->fsisig2, "rrAa", 4)
637 		    && !bcmp(fp->fsisig3, "\0\0\125\252", 4)) {
638 			pmp->pm_nxtfree = getulong(fp->fsinxtfree);
639 			if (pmp->pm_nxtfree > pmp->pm_maxcluster)
640 				pmp->pm_nxtfree = CLUST_FIRST;
641 		} else
642 			pmp->pm_fsinfo = 0;
643 		brelse(bp);
644 		bp = NULL;
645 	}
646 
647 	/*
648 	 * Finish initializing pmp->pm_nxtfree (just in case the first few
649 	 * sectors aren't properly reserved in the FAT).  This completes
650 	 * the fixup for fp->fsinxtfree, and fixes up the zero-initialized
651 	 * value if there is no fsinfo.  We will use pmp->pm_nxtfree
652 	 * internally even if there is no fsinfo.
653 	 */
654 	if (pmp->pm_nxtfree < CLUST_FIRST)
655 		pmp->pm_nxtfree = CLUST_FIRST;
656 
657 	/*
658 	 * Allocate memory for the bitmap of allocated clusters, and then
659 	 * fill it in.
660 	 */
661 	pmp->pm_inusemap = malloc(howmany(pmp->pm_maxcluster + 1, N_INUSEBITS)
662 				  * sizeof(*pmp->pm_inusemap),
663 				  M_MSDOSFSFAT, M_WAITOK);
664 
665 	/*
666 	 * fillinusemap() needs pm_devvp.
667 	 */
668 	pmp->pm_devvp = devvp;
669 	pmp->pm_dev = dev;
670 
671 	/*
672 	 * Have the inuse map filled in.
673 	 */
674 	MSDOSFS_LOCK_MP(pmp);
675 	error = fillinusemap(pmp);
676 	MSDOSFS_UNLOCK_MP(pmp);
677 	if (error != 0)
678 		goto error_exit;
679 
680 	/*
681 	 * If they want FAT updates to be synchronous then let them suffer
682 	 * the performance degradation in exchange for the on disk copy of
683 	 * the FAT being correct just about all the time.  I suppose this
684 	 * would be a good thing to turn on if the kernel is still flakey.
685 	 */
686 	if (mp->mnt_flag & MNT_SYNCHRONOUS)
687 		pmp->pm_flags |= MSDOSFSMNT_WAITONFAT;
688 
689 	/*
690 	 * Finish up.
691 	 */
692 	if (ronly)
693 		pmp->pm_flags |= MSDOSFSMNT_RONLY;
694 	else {
695 		if ((error = markvoldirty(pmp, 1)) != 0) {
696 			(void)markvoldirty(pmp, 0);
697 			goto error_exit;
698 		}
699 		pmp->pm_fmod = 1;
700 	}
701 	mp->mnt_data =  pmp;
702 	mp->mnt_stat.f_fsid.val[0] = dev2udev(dev);
703 	mp->mnt_stat.f_fsid.val[1] = mp->mnt_vfc->vfc_typenum;
704 	MNT_ILOCK(mp);
705 	mp->mnt_flag |= MNT_LOCAL;
706 	mp->mnt_kern_flag |= MNTK_USES_BCACHE | MNTK_NO_IOPF;
707 	MNT_IUNLOCK(mp);
708 
709 	return (0);
710 
711 error_exit:
712 	if (bp)
713 		brelse(bp);
714 	if (cp != NULL) {
715 		g_topology_lock();
716 		g_vfs_close(cp);
717 		g_topology_unlock();
718 	}
719 	if (pmp) {
720 		lockdestroy(&pmp->pm_fatlock);
721 		free(pmp->pm_inusemap, M_MSDOSFSFAT);
722 		free(pmp, M_MSDOSFSMNT);
723 		mp->mnt_data = NULL;
724 	}
725 	atomic_store_rel_ptr((uintptr_t *)&dev->si_mountpt, 0);
726 	dev_rel(dev);
727 	return (error);
728 }
729 
730 /*
731  * Unmount the filesystem described by mp.
732  */
733 static int
734 msdosfs_unmount(struct mount *mp, int mntflags)
735 {
736 	struct msdosfsmount *pmp;
737 	int error, flags;
738 
739 	error = flags = 0;
740 	pmp = VFSTOMSDOSFS(mp);
741 	if ((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0)
742 		error = msdosfs_sync(mp, MNT_WAIT);
743 	if ((mntflags & MNT_FORCE) != 0)
744 		flags |= FORCECLOSE;
745 	else if (error != 0)
746 		return (error);
747 	error = vflush(mp, 0, flags, curthread);
748 	if (error != 0 && error != ENXIO)
749 		return (error);
750 	if ((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0) {
751 		error = markvoldirty(pmp, 0);
752 		if (error && error != ENXIO) {
753 			(void)markvoldirty(pmp, 1);
754 			return (error);
755 		}
756 	}
757 	if (pmp->pm_flags & MSDOSFSMNT_KICONV && msdosfs_iconv) {
758 		if (pmp->pm_w2u)
759 			msdosfs_iconv->close(pmp->pm_w2u);
760 		if (pmp->pm_u2w)
761 			msdosfs_iconv->close(pmp->pm_u2w);
762 		if (pmp->pm_d2u)
763 			msdosfs_iconv->close(pmp->pm_d2u);
764 		if (pmp->pm_u2d)
765 			msdosfs_iconv->close(pmp->pm_u2d);
766 	}
767 
768 #ifdef MSDOSFS_DEBUG
769 	{
770 		struct vnode *vp = pmp->pm_devvp;
771 		struct bufobj *bo;
772 
773 		bo = &vp->v_bufobj;
774 		BO_LOCK(bo);
775 		VI_LOCK(vp);
776 		vn_printf(vp,
777 		    "msdosfs_umount(): just before calling VOP_CLOSE()\n");
778 		printf("freef %p, freeb %p, mount %p\n",
779 		    TAILQ_NEXT(vp, v_actfreelist), vp->v_actfreelist.tqe_prev,
780 		    vp->v_mount);
781 		printf("cleanblkhd %p, dirtyblkhd %p, numoutput %ld, type %d\n",
782 		    TAILQ_FIRST(&vp->v_bufobj.bo_clean.bv_hd),
783 		    TAILQ_FIRST(&vp->v_bufobj.bo_dirty.bv_hd),
784 		    vp->v_bufobj.bo_numoutput, vp->v_type);
785 		VI_UNLOCK(vp);
786 		BO_UNLOCK(bo);
787 	}
788 #endif
789 	g_topology_lock();
790 	g_vfs_close(pmp->pm_cp);
791 	g_topology_unlock();
792 	atomic_store_rel_ptr((uintptr_t *)&pmp->pm_dev->si_mountpt, 0);
793 	vrele(pmp->pm_devvp);
794 	dev_rel(pmp->pm_dev);
795 	free(pmp->pm_inusemap, M_MSDOSFSFAT);
796 	lockdestroy(&pmp->pm_fatlock);
797 	free(pmp, M_MSDOSFSMNT);
798 	mp->mnt_data = NULL;
799 	MNT_ILOCK(mp);
800 	mp->mnt_flag &= ~MNT_LOCAL;
801 	MNT_IUNLOCK(mp);
802 	return (error);
803 }
804 
805 static int
806 msdosfs_root(struct mount *mp, int flags, struct vnode **vpp)
807 {
808 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
809 	struct denode *ndep;
810 	int error;
811 
812 #ifdef MSDOSFS_DEBUG
813 	printf("msdosfs_root(); mp %p, pmp %p\n", mp, pmp);
814 #endif
815 	error = deget(pmp, MSDOSFSROOT, MSDOSFSROOT_OFS, &ndep);
816 	if (error)
817 		return (error);
818 	*vpp = DETOV(ndep);
819 	return (0);
820 }
821 
822 static int
823 msdosfs_statfs(struct mount *mp, struct statfs *sbp)
824 {
825 	struct msdosfsmount *pmp;
826 
827 	pmp = VFSTOMSDOSFS(mp);
828 	sbp->f_bsize = pmp->pm_bpcluster;
829 	sbp->f_iosize = pmp->pm_bpcluster;
830 	sbp->f_blocks = pmp->pm_maxcluster + 1;
831 	sbp->f_bfree = pmp->pm_freeclustercount;
832 	sbp->f_bavail = pmp->pm_freeclustercount;
833 	sbp->f_files = pmp->pm_RootDirEnts;	/* XXX */
834 	sbp->f_ffree = 0;	/* what to put in here? */
835 	return (0);
836 }
837 
838 /*
839  * If we have an FSInfo block, update it.
840  */
841 static int
842 msdosfs_fsiflush(struct msdosfsmount *pmp, int waitfor)
843 {
844 	struct fsinfo *fp;
845 	struct buf *bp;
846 	int error;
847 
848 	MSDOSFS_LOCK_MP(pmp);
849 	if (pmp->pm_fsinfo == 0 || (pmp->pm_flags & MSDOSFS_FSIMOD) == 0) {
850 		error = 0;
851 		goto unlock;
852 	}
853 	error = bread(pmp->pm_devvp, pmp->pm_fsinfo, pmp->pm_BytesPerSec,
854 	    NOCRED, &bp);
855 	if (error != 0) {
856 		brelse(bp);
857 		goto unlock;
858 	}
859 	fp = (struct fsinfo *)bp->b_data;
860 	putulong(fp->fsinfree, pmp->pm_freeclustercount);
861 	putulong(fp->fsinxtfree, pmp->pm_nxtfree);
862 	pmp->pm_flags &= ~MSDOSFS_FSIMOD;
863 	if (waitfor == MNT_WAIT)
864 		error = bwrite(bp);
865 	else
866 		bawrite(bp);
867 unlock:
868 	MSDOSFS_UNLOCK_MP(pmp);
869 	return (error);
870 }
871 
872 static int
873 msdosfs_sync(struct mount *mp, int waitfor)
874 {
875 	struct vnode *vp, *nvp;
876 	struct thread *td;
877 	struct denode *dep;
878 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
879 	int error, allerror = 0;
880 
881 	td = curthread;
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 loop:
898 	MNT_VNODE_FOREACH_ALL(vp, mp, nvp) {
899 		if (vp->v_type == VNON) {
900 			VI_UNLOCK(vp);
901 			continue;
902 		}
903 		dep = VTODE(vp);
904 		if ((dep->de_flag &
905 		    (DE_ACCESS | DE_CREATE | DE_UPDATE | DE_MODIFIED)) == 0 &&
906 		    (vp->v_bufobj.bo_dirty.bv_cnt == 0 ||
907 		    waitfor == MNT_LAZY)) {
908 			VI_UNLOCK(vp);
909 			continue;
910 		}
911 		error = vget(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_INTERLOCK, td);
912 		if (error) {
913 			if (error == ENOENT)
914 				goto loop;
915 			continue;
916 		}
917 		error = VOP_FSYNC(vp, waitfor, td);
918 		if (error)
919 			allerror = error;
920 		VOP_UNLOCK(vp, 0);
921 		vrele(vp);
922 	}
923 
924 	/*
925 	 * Flush filesystem control info.
926 	 */
927 	if (waitfor != MNT_LAZY) {
928 		vn_lock(pmp->pm_devvp, LK_EXCLUSIVE | LK_RETRY);
929 		error = VOP_FSYNC(pmp->pm_devvp, waitfor, td);
930 		if (error)
931 			allerror = error;
932 		VOP_UNLOCK(pmp->pm_devvp, 0);
933 	}
934 
935 	error = msdosfs_fsiflush(pmp, waitfor);
936 	if (error != 0)
937 		allerror = error;
938 	return (allerror);
939 }
940 
941 static int
942 msdosfs_fhtovp(struct mount *mp, struct fid *fhp, int flags, struct vnode **vpp)
943 {
944 	struct msdosfsmount *pmp = VFSTOMSDOSFS(mp);
945 	struct defid *defhp = (struct defid *) fhp;
946 	struct denode *dep;
947 	int error;
948 
949 	error = deget(pmp, defhp->defid_dirclust, defhp->defid_dirofs, &dep);
950 	if (error) {
951 		*vpp = NULLVP;
952 		return (error);
953 	}
954 	*vpp = DETOV(dep);
955 	vnode_create_vobject(*vpp, dep->de_FileSize, curthread);
956 	return (0);
957 }
958 
959 static struct vfsops msdosfs_vfsops = {
960 	.vfs_fhtovp =		msdosfs_fhtovp,
961 	.vfs_mount =		msdosfs_mount,
962 	.vfs_cmount =		msdosfs_cmount,
963 	.vfs_root =		msdosfs_root,
964 	.vfs_statfs =		msdosfs_statfs,
965 	.vfs_sync =		msdosfs_sync,
966 	.vfs_unmount =		msdosfs_unmount,
967 };
968 
969 VFS_SET(msdosfs_vfsops, msdosfs, 0);
970 MODULE_VERSION(msdosfs, 1);
971