xref: /openbsd/sys/msdosfs/msdosfs_denode.c (revision 5b133f3f)
1 /*	$OpenBSD: msdosfs_denode.c,v 1.68 2023/03/08 04:43:08 guenther Exp $	*/
2 /*	$NetBSD: msdosfs_denode.c,v 1.23 1997/10/17 11:23:58 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/mount.h>
54 #include <sys/malloc.h>
55 #include <sys/buf.h>
56 #include <sys/vnode.h>
57 #include <sys/lock.h>
58 #include <sys/kernel.h>		/* defines "time" */
59 #include <sys/dirent.h>
60 #include <sys/namei.h>
61 
62 #include <crypto/siphash.h>
63 
64 #include <msdosfs/bpb.h>
65 #include <msdosfs/msdosfsmount.h>
66 #include <msdosfs/direntry.h>
67 #include <msdosfs/denode.h>
68 #include <msdosfs/fat.h>
69 
70 u_int msdosfs_dehash(dev_t, uint32_t, uint32_t);
71 
72 struct denode **dehashtbl;
73 SIPHASH_KEY dehashkey;
74 u_long dehash;			/* size of hash table - 1 */
75 #define	DEHASH(dev, dcl, doff) msdosfs_dehash((dev), (dcl), (doff))
76 
77 static struct denode *msdosfs_hashget(dev_t, uint32_t, uint32_t);
78 static int msdosfs_hashins(struct denode *);
79 static void msdosfs_hashrem(struct denode *);
80 
81 int
msdosfs_init(struct vfsconf * vfsp)82 msdosfs_init(struct vfsconf *vfsp)
83 {
84 	dehashtbl = hashinit(initialvnodes / 2, M_MSDOSFSMNT, M_WAITOK, &dehash);
85 	arc4random_buf(&dehashkey, sizeof(dehashkey));
86 	return (0);
87 }
88 
89 u_int
msdosfs_dehash(dev_t dev,uint32_t dirclust,uint32_t diroff)90 msdosfs_dehash(dev_t dev, uint32_t dirclust, uint32_t diroff)
91 {
92 	SIPHASH_CTX ctx;
93 
94 	SipHash24_Init(&ctx, &dehashkey);
95 	SipHash24_Update(&ctx, &dev, sizeof(dev));
96 	SipHash24_Update(&ctx, &dirclust, sizeof(dirclust));
97 	SipHash24_Update(&ctx, &diroff, sizeof(diroff));
98 
99 	return (SipHash24_End(&ctx) & dehash);
100 }
101 
102 static struct denode *
msdosfs_hashget(dev_t dev,uint32_t dirclust,uint32_t diroff)103 msdosfs_hashget(dev_t dev, uint32_t dirclust, uint32_t diroff)
104 {
105 	struct denode *dep;
106 
107 	for (;;)
108 		for (dep = dehashtbl[DEHASH(dev, dirclust, diroff)]; ;
109 		     dep = dep->de_next) {
110 			if (dep == NULL)
111 				return (NULL);
112 			if (dirclust == dep->de_dirclust &&
113 			    diroff == dep->de_diroffset &&
114 			    dev == dep->de_dev &&
115 			    dep->de_refcnt != 0) {
116 				struct vnode *vp = DETOV(dep);
117 
118 				if (!vget(vp, LK_EXCLUSIVE))
119 					return (dep);
120 				break;
121 			}
122 		}
123 	/* NOTREACHED */
124 }
125 
126 static int
msdosfs_hashins(struct denode * dep)127 msdosfs_hashins(struct denode *dep)
128 {
129 	struct denode **depp, *deq;
130 
131 	depp = &dehashtbl[DEHASH(dep->de_dev, dep->de_dirclust,
132 				 dep->de_diroffset)];
133 
134 	for (deq = *depp; deq; deq = deq->de_next) {
135 		if (dep->de_dirclust == deq->de_dirclust &&
136 		    dep->de_diroffset == deq->de_diroffset &&
137 		    dep->de_dev == deq->de_dev &&
138 		    deq->de_refcnt != 0) {
139 			return (EEXIST);
140 		}
141 	}
142 
143 	if ((deq = *depp) != NULL)
144 		deq->de_prev = &dep->de_next;
145 	dep->de_next = deq;
146 	dep->de_prev = depp;
147 	*depp = dep;
148 	return (0);
149 }
150 
151 static void
msdosfs_hashrem(struct denode * dep)152 msdosfs_hashrem(struct denode *dep)
153 {
154 	struct denode *deq;
155 
156 	if (dep->de_prev == NULL)
157 		return;
158 
159 	if ((deq = dep->de_next) != NULL)
160 		deq->de_prev = dep->de_prev;
161 	*dep->de_prev = deq;
162 #ifdef DIAGNOSTIC
163 	dep->de_next = NULL;
164 	dep->de_prev = NULL;
165 #endif
166 }
167 
168 /*
169  * If deget() succeeds it returns with the gotten denode locked().
170  *
171  * pmp	     - address of msdosfsmount structure of the filesystem containing
172  *	       the denode of interest.  The pm_dev field and the address of
173  *	       the msdosfsmount structure are used.
174  * dirclust  - which cluster bp contains, if dirclust is 0 (root directory)
175  *	       diroffset is relative to the beginning of the root directory,
176  *	       otherwise it is cluster relative.
177  * diroffset - offset past begin of cluster of denode we want
178  * depp	     - returns the address of the gotten denode.
179  */
180 int
deget(struct msdosfsmount * pmp,uint32_t dirclust,uint32_t diroffset,struct denode ** depp)181 deget(struct msdosfsmount *pmp, uint32_t dirclust, uint32_t diroffset,
182     struct denode **depp)
183 {
184 	int error;
185 	extern const struct vops msdosfs_vops;
186 	struct direntry *direntptr;
187 	struct denode *ldep;
188 	struct vnode *nvp;
189 	struct buf *bp;
190 
191 #ifdef MSDOSFS_DEBUG
192 	printf("deget(pmp %p, dirclust %d, diroffset %x, depp %p)\n",
193 	    pmp, dirclust, diroffset, depp);
194 #endif
195 
196 	/*
197 	 * On FAT32 filesystems, root is a (more or less) normal
198 	 * directory
199 	 */
200 	if (FAT32(pmp) && dirclust == MSDOSFSROOT)
201 		dirclust = pmp->pm_rootdirblk;
202 
203 	/*
204 	 * See if the denode is in the denode cache. Use the location of
205 	 * the directory entry to compute the hash value. For subdir use
206 	 * address of "." entry. For root dir (if not FAT32) use cluster
207 	 * MSDOSFSROOT, offset MSDOSFSROOT_OFS
208 	 *
209 	 * NOTE: The check for de_refcnt > 0 below insures the denode being
210 	 * examined does not represent an unlinked but still open file.
211 	 * These files are not to be accessible even when the directory
212 	 * entry that represented the file happens to be reused while the
213 	 * deleted file is still open.
214 	 */
215 retry:
216 	ldep = msdosfs_hashget(pmp->pm_dev, dirclust, diroffset);
217 	if (ldep) {
218 		*depp = ldep;
219 		return (0);
220 	}
221 
222 	/*
223 	 * Directory entry was not in cache, have to create a vnode and
224 	 * copy it from the passed disk buffer.
225 	 */
226 	/* getnewvnode() does a vref() on the vnode */
227 	error = getnewvnode(VT_MSDOSFS, pmp->pm_mountp, &msdosfs_vops, &nvp);
228 	if (error) {
229 		*depp = 0;
230 		return (error);
231 	}
232 	ldep = malloc(sizeof(*ldep), M_MSDOSFSNODE, M_WAITOK | M_ZERO);
233 	rrw_init_flags(&ldep->de_lock, "denode", RWL_DUPOK | RWL_IS_VNODE);
234 	nvp->v_data = ldep;
235 	ldep->de_vnode = nvp;
236 	ldep->de_flag = 0;
237 	ldep->de_devvp = 0;
238 	ldep->de_lockf = 0;
239 	ldep->de_dev = pmp->pm_dev;
240 	ldep->de_dirclust = dirclust;
241 	ldep->de_diroffset = diroffset;
242 	fc_purge(ldep, 0);	/* init the fat cache for this denode */
243 
244 	/*
245 	 * Insert the denode into the hash queue and lock the denode so it
246 	 * can't be accessed until we've read it in and have done what we
247 	 * need to it.
248 	 */
249 	vn_lock(nvp, LK_EXCLUSIVE | LK_RETRY);
250 	error = msdosfs_hashins(ldep);
251 
252 	if (error) {
253 		vput (nvp);
254 
255 		if (error == EEXIST)
256 			goto retry;
257 
258 		return (error);
259 	}
260 
261 	ldep->de_pmp = pmp;
262 	ldep->de_devvp = pmp->pm_devvp;
263 	ldep->de_refcnt = 1;
264 	/*
265 	 * Copy the directory entry into the denode area of the vnode.
266 	 */
267 	if ((dirclust == MSDOSFSROOT
268 	     || (FAT32(pmp) && dirclust == pmp->pm_rootdirblk))
269 	    && diroffset == MSDOSFSROOT_OFS) {
270 		/*
271 		 * Directory entry for the root directory. There isn't one,
272 		 * so we manufacture one. We should probably rummage
273 		 * through the root directory and find a label entry (if it
274 		 * exists), and then use the time and date from that entry
275 		 * as the time and date for the root denode.
276 		 */
277 	        nvp->v_flag |= VROOT; /* should be further down         XXX */
278 
279 		ldep->de_Attributes = ATTR_DIRECTORY;
280 		if (FAT32(pmp))
281 		        ldep->de_StartCluster = pmp->pm_rootdirblk;
282 		        /* de_FileSize will be filled in further down */
283 		else {
284 		        ldep->de_StartCluster = MSDOSFSROOT;
285 		        ldep->de_FileSize = pmp->pm_rootdirsize * pmp->pm_BytesPerSec;
286 		}
287 		/*
288 		 * fill in time and date so that dos2unixtime() doesn't
289 		 * spit up when called from msdosfs_getattr() with root
290 		 * denode
291 		 */
292 		ldep->de_CTime = 0x0000;	/* 00:00:00	 */
293 		ldep->de_CTimeHundredth = 0;
294 		ldep->de_CDate = (0 << DD_YEAR_SHIFT) | (1 << DD_MONTH_SHIFT)
295 		    | (1 << DD_DAY_SHIFT);
296 		/* Jan 1, 1980	 */
297 		ldep->de_ADate = ldep->de_CDate;
298 		ldep->de_MTime = ldep->de_CTime;
299 		ldep->de_MDate = ldep->de_CDate;
300 		/* leave the other fields as garbage */
301 	} else {
302 		error = readep(pmp, dirclust, diroffset, &bp, &direntptr);
303 		if (error)
304 			return (error);
305 		DE_INTERNALIZE(ldep, direntptr);
306 		brelse(bp);
307 	}
308 
309 	/*
310 	 * Fill in a few fields of the vnode and finish filling in the
311 	 * denode.  Then return the address of the found denode.
312 	 */
313 	if (ldep->de_Attributes & ATTR_DIRECTORY) {
314 		/*
315 		 * Since DOS directory entries that describe directories
316 		 * have 0 in the filesize field, we take this opportunity
317 		 * to find out the length of the directory and plug it into
318 		 * the denode structure.
319 		 */
320 		uint32_t size;
321 
322 		nvp->v_type = VDIR;
323 		if (ldep->de_StartCluster != MSDOSFSROOT) {
324 			error = pcbmap(ldep, CLUST_END, 0, &size, 0);
325 			if (error == E2BIG) {
326 				ldep->de_FileSize = de_cn2off(pmp, size);
327 				error = 0;
328 			} else if (error) {
329 				printf("deget(): pcbmap returned %d\n", error);
330 				return (error);
331 			}
332 		}
333 	} else
334 		nvp->v_type = VREG;
335 	vref(ldep->de_devvp);
336 	*depp = ldep;
337 	return (0);
338 }
339 
340 int
deupdat(struct denode * dep,int waitfor)341 deupdat(struct denode *dep, int waitfor)
342 {
343 	struct buf *bp;
344 	struct direntry *dirp;
345 	int error;
346 	struct timespec ts;
347 
348 	if (DETOV(dep)->v_mount->mnt_flag & MNT_RDONLY)
349 		return (0);
350 	getnanotime(&ts);
351 	DETIMES(dep, &ts, &ts, &ts);
352 	if ((dep->de_flag & DE_MODIFIED) == 0)
353 		return (0);
354 	dep->de_flag &= ~DE_MODIFIED;
355 	if (dep->de_Attributes & ATTR_DIRECTORY)
356 		return (0);
357 	if (dep->de_refcnt <= 0)
358 		return (0);
359 	error = readde(dep, &bp, &dirp);
360 	if (error)
361 		return (error);
362 	DE_EXTERNALIZE(dirp, dep);
363 	if (waitfor)
364 		return (bwrite(bp));
365 	else {
366 		bdwrite(bp);
367 		return (0);
368 	}
369 }
370 
371 /*
372  * Truncate the file described by dep to the length specified by length.
373  */
374 int
detrunc(struct denode * dep,uint32_t length,int flags,struct ucred * cred,struct proc * p)375 detrunc(struct denode *dep, uint32_t length, int flags, struct ucred *cred,
376     struct proc *p)
377 {
378 	int error;
379 	int allerror;
380 	int vflags;
381 	uint32_t eofentry;
382 	uint32_t chaintofree = 0;
383 	daddr_t bn;
384 	int boff;
385 	int isadir = dep->de_Attributes & ATTR_DIRECTORY;
386 	struct buf *bp;
387 	struct msdosfsmount *pmp = dep->de_pmp;
388 
389 #ifdef MSDOSFS_DEBUG
390 	printf("detrunc(): file %.11s, length %u, flags %d\n",
391 	    dep->de_Name, length, flags);
392 #endif
393 
394 	/*
395 	 * Disallow attempts to truncate the root directory since it is of
396 	 * fixed size.  That's just the way dos filesystems are.  We use
397 	 * the VROOT bit in the vnode because checking for the directory
398 	 * bit and a startcluster of 0 in the denode is not adequate to
399 	 * recognize the root directory at this point in a file or
400 	 * directory's life.
401 	 */
402 	if ((DETOV(dep)->v_flag & VROOT) && !FAT32(pmp)) {
403 		printf("detrunc(): can't truncate root directory, clust %u, offset %u\n",
404 		    dep->de_dirclust, dep->de_diroffset);
405 		return (EINVAL);
406 	}
407 
408 	uvm_vnp_setsize(DETOV(dep), length);
409 
410 	if (dep->de_FileSize < length)
411 		return (deextend(dep, length, cred));
412 
413 	/*
414 	 * If the desired length is 0 then remember the starting cluster of
415 	 * the file and set the StartCluster field in the directory entry
416 	 * to 0.  If the desired length is not zero, then get the number of
417 	 * the last cluster in the shortened file.  Then get the number of
418 	 * the first cluster in the part of the file that is to be freed.
419 	 * Then set the next cluster pointer in the last cluster of the
420 	 * file to CLUST_EOFE.
421 	 */
422 	if (length == 0) {
423 		chaintofree = dep->de_StartCluster;
424 		dep->de_StartCluster = 0;
425 		eofentry = ~0;
426 	} else {
427 		error = pcbmap(dep, de_clcount(pmp, length) - 1, 0,
428 			       &eofentry, 0);
429 		if (error) {
430 #ifdef MSDOSFS_DEBUG
431 			printf("detrunc(): pcbmap fails %d\n", error);
432 #endif
433 			return (error);
434 		}
435 	}
436 
437 	fc_purge(dep, de_clcount(pmp, length));
438 
439 	/*
440 	 * If the new length is not a multiple of the cluster size then we
441 	 * must zero the tail end of the new last cluster in case it
442 	 * becomes part of the file again because of a seek.
443 	 */
444 	if ((boff = length & pmp->pm_crbomask) != 0) {
445 		if (isadir) {
446 			bn = cntobn(pmp, eofentry);
447 			error = bread(pmp->pm_devvp, bn, pmp->pm_bpcluster, &bp);
448 		} else {
449 			bn = de_blk(pmp, length);
450 			error = bread(DETOV(dep), bn, pmp->pm_bpcluster, &bp);
451 		}
452 		if (error) {
453 			brelse(bp);
454 #ifdef MSDOSFS_DEBUG
455 			printf("detrunc(): bread fails %d\n", error);
456 #endif
457 			return (error);
458 		}
459 		uvm_vnp_uncache(DETOV(dep));
460 		/*
461 		 * is this the right place for it?
462 		 */
463 		bzero(bp->b_data + boff, pmp->pm_bpcluster - boff);
464 		if (flags & IO_SYNC)
465 			bwrite(bp);
466 		else
467 			bdwrite(bp);
468 	}
469 
470 	/*
471 	 * Write out the updated directory entry.  Even if the update fails
472 	 * we free the trailing clusters.
473 	 */
474 	dep->de_FileSize = length;
475 	if (!isadir)
476 		dep->de_flag |= DE_UPDATE|DE_MODIFIED;
477 	vflags = (length > 0 ? V_SAVE : 0) | V_SAVEMETA;
478 	vinvalbuf(DETOV(dep), vflags, cred, p, 0, INFSLP);
479 	allerror = deupdat(dep, 1);
480 #ifdef MSDOSFS_DEBUG
481 	printf("detrunc(): allerror %d, eofentry %d\n",
482 	       allerror, eofentry);
483 #endif
484 
485 	/*
486 	 * If we need to break the cluster chain for the file then do it
487 	 * now.
488 	 */
489 	if (eofentry != ~0) {
490 		error = fatentry(FAT_GET_AND_SET, pmp, eofentry,
491 				 &chaintofree, CLUST_EOFE);
492 		if (error) {
493 #ifdef MSDOSFS_DEBUG
494 			printf("detrunc(): fatentry errors %d\n", error);
495 #endif
496 			return (error);
497 		}
498 		fc_setcache(dep, FC_LASTFC, de_cluster(pmp, length - 1),
499 			    eofentry);
500 	}
501 
502 	/*
503 	 * Now free the clusters removed from the file because of the
504 	 * truncation.
505 	 */
506 	if (chaintofree != 0 && !MSDOSFSEOF(pmp, chaintofree))
507 		freeclusterchain(pmp, chaintofree);
508 
509 	return (allerror);
510 }
511 
512 /*
513  * Extend the file described by dep to length specified by length.
514  */
515 int
deextend(struct denode * dep,uint32_t length,struct ucred * cred)516 deextend(struct denode *dep, uint32_t length, struct ucred *cred)
517 {
518 	struct msdosfsmount *pmp = dep->de_pmp;
519 	uint32_t count;
520 	int error;
521 
522 	/*
523 	 * The root of a DOS filesystem cannot be extended.
524 	 */
525 	if ((DETOV(dep)->v_flag & VROOT) && !FAT32(pmp))
526 		return (EINVAL);
527 
528 	/*
529 	 * Directories cannot be extended.
530 	 */
531 	if (dep->de_Attributes & ATTR_DIRECTORY)
532 		return (EISDIR);
533 
534 	if (length <= dep->de_FileSize)
535 		panic("deextend: file too large");
536 
537 	/*
538 	 * Compute the number of clusters to allocate.
539 	 */
540 	count = de_clcount(pmp, length) - de_clcount(pmp, dep->de_FileSize);
541 	if (count > 0) {
542 		if (count > pmp->pm_freeclustercount)
543 			return (ENOSPC);
544 		error = extendfile(dep, count, NULL, NULL, DE_CLEAR);
545 		if (error) {
546 			/* truncate the added clusters away again */
547 			(void) detrunc(dep, dep->de_FileSize, 0, cred, curproc);
548 			return (error);
549 		}
550 	}
551 
552 	dep->de_FileSize = length;
553 	dep->de_flag |= DE_UPDATE|DE_MODIFIED;
554 	return (deupdat(dep, 1));
555 }
556 
557 /*
558  * Move a denode to its correct hash queue after the file it represents has
559  * been moved to a new directory.
560  */
561 void
reinsert(struct denode * dep)562 reinsert(struct denode *dep)
563 {
564 	/*
565 	 * Fix up the denode cache.  If the denode is for a directory,
566 	 * there is nothing to do since the hash is based on the starting
567 	 * cluster of the directory file and that hasn't changed.  If for a
568 	 * file the hash is based on the location of the directory entry,
569 	 * so we must remove it from the cache and re-enter it with the
570 	 * hash based on the new location of the directory entry.
571 	 */
572 	if (dep->de_Attributes & ATTR_DIRECTORY)
573 		return;
574 	msdosfs_hashrem(dep);
575 	msdosfs_hashins(dep);
576 }
577 
578 int
msdosfs_reclaim(void * v)579 msdosfs_reclaim(void *v)
580 {
581 	struct vop_reclaim_args *ap = v;
582 	struct vnode *vp = ap->a_vp;
583 	struct denode *dep = VTODE(vp);
584 #ifdef DIAGNOSTIC
585 	extern int prtactive;
586 
587 	if (prtactive && vp->v_usecount != 0)
588 		vprint("msdosfs_reclaim(): pushing active", vp);
589 #endif
590 
591 #ifdef MSDOSFS_DEBUG
592 	printf("msdosfs_reclaim(): dep %p, file %.11s, refcnt %ld\n",
593 	    dep, dep->de_Name, dep->de_refcnt);
594 #endif
595 
596 	/*
597 	 * Remove the denode from its hash chain.
598 	 */
599 	msdosfs_hashrem(dep);
600 	/*
601 	 * Purge old data structures associated with the denode.
602 	 */
603 	cache_purge(vp);
604 	if (dep->de_devvp) {
605 		vrele(dep->de_devvp);
606 		dep->de_devvp = 0;
607 	}
608 #if 0 /* XXX */
609 	dep->de_flag = 0;
610 #endif
611 	free(dep, M_MSDOSFSNODE, 0);
612 	vp->v_data = NULL;
613 	return (0);
614 }
615 
616 int
msdosfs_inactive(void * v)617 msdosfs_inactive(void *v)
618 {
619 	struct vop_inactive_args *ap = v;
620 	struct vnode *vp = ap->a_vp;
621 	struct denode *dep = VTODE(vp);
622 	int error;
623 #ifdef DIAGNOSTIC
624 	extern int prtactive;
625 
626 	if (prtactive && vp->v_usecount != 0)
627 		vprint("msdosfs_inactive(): pushing active", vp);
628 #endif
629 
630 #ifdef MSDOSFS_DEBUG
631 	printf("msdosfs_inactive(): dep %p, de_Name[0] %x\n", dep,
632 	    dep->de_Name[0]);
633 #endif
634 
635 	error = 0;
636 
637 	/*
638 	 * Get rid of denodes related to stale file handles.
639 	 */
640 	if (dep->de_Name[0] == SLOT_DELETED)
641 		goto out;
642 
643 	/*
644 	 * If the file has been deleted and it is on a read/write
645 	 * filesystem, then truncate the file, and mark the directory slot
646 	 * as empty.  (This may not be necessary for the dos filesystem.)
647 	 */
648 #ifdef MSDOSFS_DEBUG
649 	printf("msdosfs_inactive(): dep %p, refcnt %ld, mntflag %x, "
650 	    "MNT_RDONLY %x\n", dep, dep->de_refcnt, vp->v_mount->mnt_flag,
651 	    MNT_RDONLY);
652 #endif
653 	if (dep->de_refcnt <= 0 && (vp->v_mount->mnt_flag & MNT_RDONLY) == 0) {
654 		error = detrunc(dep, (uint32_t)0, 0, NOCRED, ap->a_p);
655 		dep->de_Name[0] = SLOT_DELETED;
656 	}
657 	deupdat(dep, 0);
658 
659 out:
660 	VOP_UNLOCK(vp);
661 	/*
662 	 * If we are done with the denode, reclaim it
663 	 * so that it can be reused immediately.
664 	 */
665 #ifdef MSDOSFS_DEBUG
666 	printf("msdosfs_inactive(): v_usecount %d, de_Name[0] %x\n",
667 	    vp->v_usecount, dep->de_Name[0]);
668 #endif
669 	if (dep->de_Name[0] == SLOT_DELETED)
670 		vrecycle(vp, ap->a_p);
671 	return (error);
672 }
673