1 /* $FreeBSD$ */
2 /* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 ws Exp $ */
3
4 /*-
5 * SPDX-License-Identifier: BSD-4-Clause
6 *
7 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
8 * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
9 * All rights reserved.
10 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by TooLs GmbH.
23 * 4. The name of TooLs GmbH may not be used to endorse or promote products
24 * derived from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
31 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
32 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
33 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
34 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
35 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 */
37 /*-
38 * Written by Paul Popelka (paulp@uts.amdahl.com)
39 *
40 * You can do anything you want with this software, just don't say you wrote
41 * it, and don't remove this notice.
42 *
43 * This software is provided "as is".
44 *
45 * The author supplies this software to be publicly redistributed on the
46 * understanding that the author is not responsible for the correct
47 * functioning of this software in any circumstances and is not liable for
48 * any damages caused by this software.
49 *
50 * October 1992
51 */
52
53 #include <sys/param.h>
54 #include <sys/systm.h>
55 #include <sys/buf.h>
56 #include <sys/mount.h>
57 #include <sys/vmmeter.h>
58 #include <sys/vnode.h>
59
60 #include <fs/msdosfs/bpb.h>
61 #include <fs/msdosfs/direntry.h>
62 #include <fs/msdosfs/denode.h>
63 #include <fs/msdosfs/fat.h>
64 #include <fs/msdosfs/msdosfsmount.h>
65
66 #define FULL_RUN ((u_int)0xffffffff)
67
68 static int chainalloc(struct msdosfsmount *pmp, u_long start,
69 u_long count, u_long fillwith, u_long *retcluster,
70 u_long *got);
71 static int chainlength(struct msdosfsmount *pmp, u_long start,
72 u_long count);
73 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp,
74 u_long *sizep, u_long *bop);
75 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count,
76 u_long fillwith);
77 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp,
78 u_long *fsrcnp);
79 static void updatefats(struct msdosfsmount *pmp, struct buf *bp,
80 u_long fatbn);
81 static __inline void
82 usemap_alloc(struct msdosfsmount *pmp, u_long cn);
83 static int usemap_free(struct msdosfsmount *pmp, u_long cn);
84 static int clusteralloc1(struct msdosfsmount *pmp, u_long start,
85 u_long count, u_long fillwith, u_long *retcluster,
86 u_long *got);
87
88 static void
89 fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep,
90 u_long *bop)
91 {
92 u_long bn, size;
93
94 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec;
95 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn)
96 * DEV_BSIZE;
97 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs;
98
99 if (bnp)
100 *bnp = bn;
101 if (sizep)
102 *sizep = size;
103 if (bop)
104 *bop = ofs % pmp->pm_fatblocksize;
105 }
106
107 /*
108 * Map the logical cluster number of a file into a physical disk sector
109 * that is filesystem relative.
110 *
111 * dep - address of denode representing the file of interest
112 * findcn - file relative cluster whose filesystem relative cluster number
113 * and/or block number are/is to be found
114 * bnp - address of where to place the filesystem relative block number.
115 * If this pointer is null then don't return this quantity.
116 * cnp - address of where to place the filesystem relative cluster number.
117 * If this pointer is null then don't return this quantity.
118 * sp - pointer to returned block size
119 *
120 * NOTE: Either bnp or cnp must be non-null.
121 * This function has one side effect. If the requested file relative cluster
122 * is beyond the end of file, then the actual number of clusters in the file
123 * is returned in *cnp. This is useful for determining how long a directory is.
124 * If cnp is null, nothing is returned.
125 */
126 int
127 pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp)
128 {
129 int error;
130 u_long i;
131 u_long cn;
132 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */
133 u_long byteoffset;
134 u_long bn;
135 u_long bo;
136 struct buf *bp = NULL;
137 u_long bp_bn = -1;
138 struct msdosfsmount *pmp = dep->de_pmp;
139 u_long bsize;
140
141 KASSERT(bnp != NULL || cnp != NULL || sp != NULL,
142 ("pcbmap: extra call"));
143 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap");
144
145 cn = dep->de_StartCluster;
146 /*
147 * The "file" that makes up the root directory is contiguous,
148 * permanently allocated, of fixed size, and is not made up of
149 * clusters. If the cluster number is beyond the end of the root
150 * directory, then return the number of clusters in the file.
151 */
152 if (cn == MSDOSFSROOT) {
153 if (dep->de_Attributes & ATTR_DIRECTORY) {
154 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) {
155 if (cnp)
156 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize);
157 return (E2BIG);
158 }
159 if (bnp)
160 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn);
161 if (cnp)
162 *cnp = MSDOSFSROOT;
163 if (sp)
164 *sp = min(pmp->pm_bpcluster,
165 dep->de_FileSize - de_cn2off(pmp, findcn));
166 return (0);
167 } else { /* just an empty file */
168 if (cnp)
169 *cnp = 0;
170 return (E2BIG);
171 }
172 }
173
174 /*
175 * All other files do I/O in cluster sized blocks
176 */
177 if (sp)
178 *sp = pmp->pm_bpcluster;
179
180 /*
181 * Rummage around in the FAT cache, maybe we can avoid tromping
182 * through every FAT entry for the file. And, keep track of how far
183 * off the cache was from where we wanted to be.
184 */
185 i = 0;
186 fc_lookup(dep, findcn, &i, &cn);
187
188 /*
189 * Handle all other files or directories the normal way.
190 */
191 for (; i < findcn; i++) {
192 /*
193 * Stop with all reserved clusters, not just with EOF.
194 */
195 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
196 goto hiteof;
197 byteoffset = FATOFS(pmp, cn);
198 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
199 if (bn != bp_bn) {
200 if (bp)
201 brelse(bp);
202 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
203 if (error) {
204 return (error);
205 }
206 bp_bn = bn;
207 }
208 prevcn = cn;
209 if (bo >= bsize) {
210 if (bp)
211 brelse(bp);
212 return (EIO);
213 }
214 if (FAT32(pmp))
215 cn = getulong(bp->b_data + bo);
216 else
217 cn = getushort(bp->b_data + bo);
218 if (FAT12(pmp) && (prevcn & 1))
219 cn >>= 4;
220 cn &= pmp->pm_fatmask;
221
222 /*
223 * Force the special cluster numbers
224 * to be the same for all cluster sizes
225 * to let the rest of msdosfs handle
226 * all cases the same.
227 */
228 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
229 cn |= ~pmp->pm_fatmask;
230 }
231
232 if (!MSDOSFSEOF(pmp, cn)) {
233 if (bp)
234 brelse(bp);
235 if (bnp)
236 *bnp = cntobn(pmp, cn);
237 if (cnp)
238 *cnp = cn;
239 fc_setcache(dep, FC_LASTMAP, i, cn);
240 return (0);
241 }
242
243 hiteof:;
244 if (cnp)
245 *cnp = i;
246 if (bp)
247 brelse(bp);
248 /* update last file cluster entry in the FAT cache */
249 fc_setcache(dep, FC_LASTFC, i - 1, prevcn);
250 return (E2BIG);
251 }
252
253 /*
254 * Find the closest entry in the FAT cache to the cluster we are looking
255 * for.
256 */
257 static void
258 fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp)
259 {
260 int i;
261 u_long cn;
262 struct fatcache *closest = NULL;
263
264 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup");
265
266 for (i = 0; i < FC_SIZE; i++) {
267 cn = dep->de_fc[i].fc_frcn;
268 if (cn != FCE_EMPTY && cn <= findcn) {
269 if (closest == NULL || cn > closest->fc_frcn)
270 closest = &dep->de_fc[i];
271 }
272 }
273 if (closest) {
274 *frcnp = closest->fc_frcn;
275 *fsrcnp = closest->fc_fsrcn;
276 }
277 }
278
279 /*
280 * Purge the FAT cache in denode dep of all entries relating to file
281 * relative cluster frcn and beyond.
282 */
283 void
284 fc_purge(struct denode *dep, u_int frcn)
285 {
286 int i;
287 struct fatcache *fcp;
288
289 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge");
290
291 fcp = dep->de_fc;
292 for (i = 0; i < FC_SIZE; i++, fcp++) {
293 if (fcp->fc_frcn >= frcn)
294 fcp->fc_frcn = FCE_EMPTY;
295 }
296 }
297
298 /*
299 * Update the FAT.
300 * If mirroring the FAT, update all copies, with the first copy as last.
301 * Else update only the current FAT (ignoring the others).
302 *
303 * pmp - msdosfsmount structure for filesystem to update
304 * bp - addr of modified FAT block
305 * fatbn - block number relative to begin of filesystem of the modified FAT block.
306 */
307 static void
308 updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn)
309 {
310 struct buf *bpn;
311 int cleanfat, i;
312
313 #ifdef MSDOSFS_DEBUG
314 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn);
315 #endif
316
317 if (pmp->pm_flags & MSDOSFS_FATMIRROR) {
318 /*
319 * Now copy the block(s) of the modified FAT to the other copies of
320 * the FAT and write them out. This is faster than reading in the
321 * other FATs and then writing them back out. This could tie up
322 * the FAT for quite a while. Preventing others from accessing it.
323 * To prevent us from going after the FAT quite so much we use
324 * delayed writes, unless they specified "synchronous" when the
325 * filesystem was mounted. If synch is asked for then use
326 * bwrite()'s and really slow things down.
327 */
328 if (fatbn != pmp->pm_fatblk || FAT12(pmp))
329 cleanfat = 0;
330 else if (FAT16(pmp))
331 cleanfat = 16;
332 else
333 cleanfat = 32;
334 for (i = 1; i < pmp->pm_FATs; i++) {
335 fatbn += pmp->pm_FATsecs;
336 /* getblk() never fails */
337 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount,
338 0, 0, 0);
339 memcpy(bpn->b_data, bp->b_data, bp->b_bcount);
340 /* Force the clean bit on in the other copies. */
341 if (cleanfat == 16)
342 ((uint8_t *)bpn->b_data)[3] |= 0x80;
343 else if (cleanfat == 32)
344 ((uint8_t *)bpn->b_data)[7] |= 0x08;
345 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS)
346 bwrite(bpn);
347 else
348 bdwrite(bpn);
349 }
350 }
351
352 /*
353 * Write out the first (or current) FAT last.
354 */
355 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS)
356 bwrite(bp);
357 else
358 bdwrite(bp);
359 }
360
361 /*
362 * Updating entries in 12 bit FATs is a pain in the butt.
363 *
364 * The following picture shows where nibbles go when moving from a 12 bit
365 * cluster number into the appropriate bytes in the FAT.
366 *
367 * byte m byte m+1 byte m+2
368 * +----+----+ +----+----+ +----+----+
369 * | 0 1 | | 2 3 | | 4 5 | FAT bytes
370 * +----+----+ +----+----+ +----+----+
371 *
372 * +----+----+----+ +----+----+----+
373 * | 3 0 1 | | 4 5 2 |
374 * +----+----+----+ +----+----+----+
375 * cluster n cluster n+1
376 *
377 * Where n is even. m = n + (n >> 2)
378 *
379 */
380 static __inline void
381 usemap_alloc(struct msdosfsmount *pmp, u_long cn)
382 {
383
384 MSDOSFS_ASSERT_MP_LOCKED(pmp);
385
386 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn,
387 pmp->pm_maxcluster));
388 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0,
389 ("usemap_alloc on ro msdosfs mount"));
390 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] &
391 (1U << (cn % N_INUSEBITS))) == 0,
392 ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS,
393 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS]));
394 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS);
395 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little"));
396 pmp->pm_freeclustercount--;
397 pmp->pm_flags |= MSDOSFS_FSIMOD;
398 }
399
400 static int
401 usemap_free(struct msdosfsmount *pmp, u_long cn)
402 {
403
404 MSDOSFS_ASSERT_MP_LOCKED(pmp);
405
406 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn,
407 pmp->pm_maxcluster));
408 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0,
409 ("usemap_free on ro msdosfs mount"));
410 if ((pmp->pm_inusemap[cn / N_INUSEBITS] &
411 (1U << (cn % N_INUSEBITS))) == 0) {
412 printf("%s: Freeing unused sector %ld %ld %x\n",
413 pmp->pm_mountp->mnt_stat.f_mntonname, cn, cn % N_INUSEBITS,
414 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS]);
415 msdosfs_integrity_error(pmp);
416 return (EINTEGRITY);
417 }
418 pmp->pm_freeclustercount++;
419 pmp->pm_flags |= MSDOSFS_FSIMOD;
420 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1U << (cn % N_INUSEBITS));
421 return (0);
422 }
423
424 void
425 clusterfree(struct msdosfsmount *pmp, u_long cluster)
426 {
427 int error;
428 u_long oldcn;
429
430 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE);
431 if (error != 0)
432 return;
433 /*
434 * If the cluster was successfully marked free, then update
435 * the count of free clusters, and turn off the "allocated"
436 * bit in the "in use" cluster bit map.
437 */
438 MSDOSFS_LOCK_MP(pmp);
439 error = usemap_free(pmp, cluster);
440 MSDOSFS_UNLOCK_MP(pmp);
441 }
442
443 /*
444 * Get or Set or 'Get and Set' the cluster'th entry in the FAT.
445 *
446 * function - whether to get or set a FAT entry
447 * pmp - address of the msdosfsmount structure for the filesystem
448 * whose FAT is to be manipulated.
449 * cn - which cluster is of interest
450 * oldcontents - address of a word that is to receive the contents of the
451 * cluster'th entry if this is a get function
452 * newcontents - the new value to be written into the cluster'th element of
453 * the FAT if this is a set function.
454 *
455 * This function can also be used to free a cluster by setting the FAT entry
456 * for a cluster to 0.
457 *
458 * All copies of the FAT are updated if this is a set function. NOTE: If
459 * fatentry() marks a cluster as free it does not update the inusemap in
460 * the msdosfsmount structure. This is left to the caller.
461 */
462 int
463 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents,
464 u_long newcontents)
465 {
466 int error;
467 u_long readcn;
468 u_long bn, bo, bsize, byteoffset;
469 struct buf *bp;
470
471 #ifdef MSDOSFS_DEBUG
472 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n",
473 function, pmp, cn, oldcontents, newcontents);
474 #endif
475
476 #ifdef DIAGNOSTIC
477 /*
478 * Be sure they asked us to do something.
479 */
480 if ((function & (FAT_SET | FAT_GET)) == 0) {
481 #ifdef MSDOSFS_DEBUG
482 printf("fatentry(): function code doesn't specify get or set\n");
483 #endif
484 return (EINVAL);
485 }
486
487 /*
488 * If they asked us to return a cluster number but didn't tell us
489 * where to put it, give them an error.
490 */
491 if ((function & FAT_GET) && oldcontents == NULL) {
492 #ifdef MSDOSFS_DEBUG
493 printf("fatentry(): get function with no place to put result\n");
494 #endif
495 return (EINVAL);
496 }
497 #endif
498
499 /*
500 * Be sure the requested cluster is in the filesystem.
501 */
502 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster)
503 return (EINVAL);
504
505 byteoffset = FATOFS(pmp, cn);
506 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
507 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
508 if (error) {
509 return (error);
510 }
511
512 if (function & FAT_GET) {
513 if (FAT32(pmp))
514 readcn = getulong(bp->b_data + bo);
515 else
516 readcn = getushort(bp->b_data + bo);
517 if (FAT12(pmp) & (cn & 1))
518 readcn >>= 4;
519 readcn &= pmp->pm_fatmask;
520 /* map reserved FAT entries to same values for all FATs */
521 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
522 readcn |= ~pmp->pm_fatmask;
523 *oldcontents = readcn;
524 }
525 if (function & FAT_SET) {
526 switch (pmp->pm_fatmask) {
527 case FAT12_MASK:
528 readcn = getushort(bp->b_data + bo);
529 if (cn & 1) {
530 readcn &= 0x000f;
531 readcn |= newcontents << 4;
532 } else {
533 readcn &= 0xf000;
534 readcn |= newcontents & 0xfff;
535 }
536 putushort(bp->b_data + bo, readcn);
537 break;
538 case FAT16_MASK:
539 putushort(bp->b_data + bo, newcontents);
540 break;
541 case FAT32_MASK:
542 /*
543 * According to spec we have to retain the
544 * high order bits of the FAT entry.
545 */
546 readcn = getulong(bp->b_data + bo);
547 readcn &= ~FAT32_MASK;
548 readcn |= newcontents & FAT32_MASK;
549 putulong(bp->b_data + bo, readcn);
550 break;
551 }
552 updatefats(pmp, bp, bn);
553 bp = NULL;
554 pmp->pm_fmod = 1;
555 }
556 if (bp)
557 brelse(bp);
558 return (0);
559 }
560
561 /*
562 * Update a contiguous cluster chain
563 *
564 * pmp - mount point
565 * start - first cluster of chain
566 * count - number of clusters in chain
567 * fillwith - what to write into FAT entry of last cluster
568 */
569 static int
570 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith)
571 {
572 int error;
573 u_long bn, bo, bsize, byteoffset, readcn, newc;
574 struct buf *bp;
575
576 #ifdef MSDOSFS_DEBUG
577 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n",
578 pmp, start, count, fillwith);
579 #endif
580 /*
581 * Be sure the clusters are in the filesystem.
582 */
583 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster)
584 return (EINVAL);
585
586 while (count > 0) {
587 byteoffset = FATOFS(pmp, start);
588 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
589 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
590 if (error) {
591 return (error);
592 }
593 while (count > 0) {
594 start++;
595 newc = --count > 0 ? start : fillwith;
596 switch (pmp->pm_fatmask) {
597 case FAT12_MASK:
598 readcn = getushort(bp->b_data + bo);
599 if (start & 1) {
600 readcn &= 0xf000;
601 readcn |= newc & 0xfff;
602 } else {
603 readcn &= 0x000f;
604 readcn |= newc << 4;
605 }
606 putushort(bp->b_data + bo, readcn);
607 bo++;
608 if (!(start & 1))
609 bo++;
610 break;
611 case FAT16_MASK:
612 putushort(bp->b_data + bo, newc);
613 bo += 2;
614 break;
615 case FAT32_MASK:
616 readcn = getulong(bp->b_data + bo);
617 readcn &= ~pmp->pm_fatmask;
618 readcn |= newc & pmp->pm_fatmask;
619 putulong(bp->b_data + bo, readcn);
620 bo += 4;
621 break;
622 }
623 if (bo >= bsize)
624 break;
625 }
626 updatefats(pmp, bp, bn);
627 }
628 pmp->pm_fmod = 1;
629 return (0);
630 }
631
632 /*
633 * Check the length of a free cluster chain starting at start.
634 *
635 * pmp - mount point
636 * start - start of chain
637 * count - maximum interesting length
638 */
639 static int
640 chainlength(struct msdosfsmount *pmp, u_long start, u_long count)
641 {
642 u_long idx, max_idx;
643 u_int map;
644 u_long len;
645
646 MSDOSFS_ASSERT_MP_LOCKED(pmp);
647
648 if (start > pmp->pm_maxcluster)
649 return (0);
650 max_idx = pmp->pm_maxcluster / N_INUSEBITS;
651 idx = start / N_INUSEBITS;
652 start %= N_INUSEBITS;
653 map = pmp->pm_inusemap[idx];
654 map &= ~((1U << start) - 1);
655 if (map) {
656 len = ffs(map) - 1 - start;
657 len = MIN(len, count);
658 if (start + len > pmp->pm_maxcluster)
659 len = pmp->pm_maxcluster - start + 1;
660 return (len);
661 }
662 len = N_INUSEBITS - start;
663 if (len >= count) {
664 len = count;
665 if (start + len > pmp->pm_maxcluster)
666 len = pmp->pm_maxcluster - start + 1;
667 return (len);
668 }
669 while (++idx <= max_idx) {
670 if (len >= count)
671 break;
672 map = pmp->pm_inusemap[idx];
673 if (map) {
674 len += ffs(map) - 1;
675 break;
676 }
677 len += N_INUSEBITS;
678 }
679 len = MIN(len, count);
680 if (start + len > pmp->pm_maxcluster)
681 len = pmp->pm_maxcluster - start + 1;
682 return (len);
683 }
684
685 /*
686 * Allocate contigous free clusters.
687 *
688 * pmp - mount point.
689 * start - start of cluster chain.
690 * count - number of clusters to allocate.
691 * fillwith - put this value into the FAT entry for the
692 * last allocated cluster.
693 * retcluster - put the first allocated cluster's number here.
694 * got - how many clusters were actually allocated.
695 */
696 static int
697 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count,
698 u_long fillwith, u_long *retcluster, u_long *got)
699 {
700 int error;
701 u_long cl, n;
702
703 MSDOSFS_ASSERT_MP_LOCKED(pmp);
704 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0,
705 ("chainalloc on ro msdosfs mount"));
706
707 for (cl = start, n = count; n-- > 0;)
708 usemap_alloc(pmp, cl++);
709 pmp->pm_nxtfree = start + count;
710 if (pmp->pm_nxtfree > pmp->pm_maxcluster)
711 pmp->pm_nxtfree = CLUST_FIRST;
712 pmp->pm_flags |= MSDOSFS_FSIMOD;
713 error = fatchain(pmp, start, count, fillwith);
714 if (error != 0) {
715 for (cl = start, n = count; n-- > 0;)
716 (void)usemap_free(pmp, cl++);
717 return (error);
718 }
719 #ifdef MSDOSFS_DEBUG
720 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n",
721 start, count);
722 #endif
723 if (retcluster)
724 *retcluster = start;
725 if (got)
726 *got = count;
727 return (0);
728 }
729
730 /*
731 * Allocate contiguous free clusters.
732 *
733 * pmp - mount point.
734 * start - preferred start of cluster chain.
735 * count - number of clusters requested.
736 * fillwith - put this value into the FAT entry for the
737 * last allocated cluster.
738 * retcluster - put the first allocated cluster's number here.
739 * got - how many clusters were actually allocated.
740 */
741 int
742 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count,
743 u_long fillwith, u_long *retcluster, u_long *got)
744 {
745 int error;
746
747 MSDOSFS_LOCK_MP(pmp);
748 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got);
749 MSDOSFS_UNLOCK_MP(pmp);
750 return (error);
751 }
752
753 static int
754 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count,
755 u_long fillwith, u_long *retcluster, u_long *got)
756 {
757 u_long idx;
758 u_long len, newst, foundl, cn, l;
759 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */
760 u_int map;
761
762 MSDOSFS_ASSERT_MP_LOCKED(pmp);
763
764 #ifdef MSDOSFS_DEBUG
765 printf("clusteralloc(): find %lu clusters\n", count);
766 #endif
767 if (start) {
768 if ((len = chainlength(pmp, start, count)) >= count)
769 return (chainalloc(pmp, start, count, fillwith, retcluster, got));
770 } else
771 len = 0;
772
773 newst = pmp->pm_nxtfree;
774 foundl = 0;
775
776 for (cn = newst; cn <= pmp->pm_maxcluster;) {
777 idx = cn / N_INUSEBITS;
778 map = pmp->pm_inusemap[idx];
779 map |= (1U << (cn % N_INUSEBITS)) - 1;
780 if (map != FULL_RUN) {
781 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1;
782 if ((l = chainlength(pmp, cn, count)) >= count)
783 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
784 if (l > foundl) {
785 foundcn = cn;
786 foundl = l;
787 }
788 cn += l + 1;
789 continue;
790 }
791 cn += N_INUSEBITS - cn % N_INUSEBITS;
792 }
793 for (cn = 0; cn < newst;) {
794 idx = cn / N_INUSEBITS;
795 map = pmp->pm_inusemap[idx];
796 map |= (1U << (cn % N_INUSEBITS)) - 1;
797 if (map != FULL_RUN) {
798 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1;
799 if ((l = chainlength(pmp, cn, count)) >= count)
800 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
801 if (l > foundl) {
802 foundcn = cn;
803 foundl = l;
804 }
805 cn += l + 1;
806 continue;
807 }
808 cn += N_INUSEBITS - cn % N_INUSEBITS;
809 }
810
811 if (!foundl)
812 return (ENOSPC);
813
814 if (len)
815 return (chainalloc(pmp, start, len, fillwith, retcluster, got));
816 else
817 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got));
818 }
819
820 /*
821 * Free a chain of clusters.
822 *
823 * pmp - address of the msdosfs mount structure for the filesystem
824 * containing the cluster chain to be freed.
825 * startcluster - number of the 1st cluster in the chain of clusters to be
826 * freed.
827 */
828 int
829 freeclusterchain(struct msdosfsmount *pmp, u_long cluster)
830 {
831 int error;
832 struct buf *bp = NULL;
833 u_long bn, bo, bsize, byteoffset;
834 u_long readcn, lbn = -1;
835
836 MSDOSFS_LOCK_MP(pmp);
837 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) {
838 byteoffset = FATOFS(pmp, cluster);
839 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
840 if (lbn != bn) {
841 if (bp)
842 updatefats(pmp, bp, lbn);
843 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
844 if (error) {
845 MSDOSFS_UNLOCK_MP(pmp);
846 return (error);
847 }
848 lbn = bn;
849 }
850 error = usemap_free(pmp, cluster);
851 if (error != 0) {
852 updatefats(pmp, bp, lbn);
853 MSDOSFS_UNLOCK_MP(pmp);
854 return (error);
855 }
856 switch (pmp->pm_fatmask) {
857 case FAT12_MASK:
858 readcn = getushort(bp->b_data + bo);
859 if (cluster & 1) {
860 cluster = readcn >> 4;
861 readcn &= 0x000f;
862 readcn |= MSDOSFSFREE << 4;
863 } else {
864 cluster = readcn;
865 readcn &= 0xf000;
866 readcn |= MSDOSFSFREE & 0xfff;
867 }
868 putushort(bp->b_data + bo, readcn);
869 break;
870 case FAT16_MASK:
871 cluster = getushort(bp->b_data + bo);
872 putushort(bp->b_data + bo, MSDOSFSFREE);
873 break;
874 case FAT32_MASK:
875 cluster = getulong(bp->b_data + bo);
876 putulong(bp->b_data + bo,
877 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK));
878 break;
879 }
880 cluster &= pmp->pm_fatmask;
881 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD)
882 cluster |= pmp->pm_fatmask;
883 }
884 if (bp)
885 updatefats(pmp, bp, bn);
886 MSDOSFS_UNLOCK_MP(pmp);
887 return (0);
888 }
889
890 /*
891 * Read in FAT blocks looking for free clusters. For every free cluster
892 * found turn off its corresponding bit in the pm_inusemap.
893 */
894 int
895 fillinusemap(struct msdosfsmount *pmp)
896 {
897 struct buf *bp;
898 u_long bn, bo, bsize, byteoffset, cn, readcn;
899 int error;
900
901 MSDOSFS_ASSERT_MP_LOCKED(pmp);
902 bp = NULL;
903
904 /*
905 * Mark all clusters in use, we mark the free ones in the FAT scan
906 * loop further down.
907 */
908 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++)
909 pmp->pm_inusemap[cn] = FULL_RUN;
910
911 /*
912 * Figure how many free clusters are in the filesystem by ripping
913 * through the FAT counting the number of entries whose content is
914 * zero. These represent free clusters.
915 */
916 pmp->pm_freeclustercount = 0;
917 for (cn = 0; cn <= pmp->pm_maxcluster; cn++) {
918 byteoffset = FATOFS(pmp, cn);
919 bo = byteoffset % pmp->pm_fatblocksize;
920 if (bo == 0) {
921 /* Read new FAT block */
922 if (bp != NULL)
923 brelse(bp);
924 fatblock(pmp, byteoffset, &bn, &bsize, NULL);
925 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
926 if (error != 0)
927 return (error);
928 }
929 if (FAT32(pmp))
930 readcn = getulong(bp->b_data + bo);
931 else
932 readcn = getushort(bp->b_data + bo);
933 if (FAT12(pmp) && (cn & 1))
934 readcn >>= 4;
935 readcn &= pmp->pm_fatmask;
936
937 /*
938 * Check if the FAT ID matches the BPB's media descriptor and
939 * all other bits are set to 1.
940 */
941 if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) |
942 pmp->pm_bpb.bpbMedia)) {
943 #ifdef MSDOSFS_DEBUG
944 printf("mountmsdosfs(): Media descriptor in BPB"
945 "does not match FAT ID\n");
946 #endif
947 brelse(bp);
948 return (EINVAL);
949 } else if (readcn == CLUST_FREE) {
950 error = usemap_free(pmp, cn);
951 if (error != 0) {
952 brelse(bp);
953 return (error);
954 }
955 }
956 }
957 if (bp != NULL)
958 brelse(bp);
959
960 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster +
961 N_INUSEBITS) / N_INUSEBITS; cn++)
962 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS);
963
964 return (0);
965 }
966
967 /*
968 * Allocate a new cluster and chain it onto the end of the file.
969 *
970 * dep - the file to extend
971 * count - number of clusters to allocate
972 * bpp - where to return the address of the buf header for the first new
973 * file block
974 * ncp - where to put cluster number of the first newly allocated cluster
975 * If this pointer is 0, do not return the cluster number.
976 * flags - see fat.h
977 *
978 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of
979 * the de_flag field of the denode and it does not change the de_FileSize
980 * field. This is left for the caller to do.
981 */
982 int
983 extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp,
984 int flags)
985 {
986 int error;
987 u_long frcn;
988 u_long cn, got;
989 struct msdosfsmount *pmp = dep->de_pmp;
990 struct buf *bp;
991 daddr_t blkno;
992
993 /*
994 * Don't try to extend the root directory
995 */
996 if (dep->de_StartCluster == MSDOSFSROOT
997 && (dep->de_Attributes & ATTR_DIRECTORY)) {
998 #ifdef MSDOSFS_DEBUG
999 printf("extendfile(): attempt to extend root directory\n");
1000 #endif
1001 return (ENOSPC);
1002 }
1003
1004 /*
1005 * If the "file's last cluster" cache entry is empty, and the file
1006 * is not empty, then fill the cache entry by calling pcbmap().
1007 */
1008 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY &&
1009 dep->de_StartCluster != 0) {
1010 error = pcbmap(dep, 0xffff, 0, &cn, 0);
1011 /* we expect it to return E2BIG */
1012 if (error != E2BIG)
1013 return (error);
1014 }
1015
1016 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn =
1017 dep->de_fc[FC_LASTFC].fc_frcn;
1018 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn =
1019 dep->de_fc[FC_LASTFC].fc_fsrcn;
1020 while (count > 0) {
1021 /*
1022 * Allocate a new cluster chain and cat onto the end of the
1023 * file. If the file is empty we make de_StartCluster point
1024 * to the new block. Note that de_StartCluster being 0 is
1025 * sufficient to be sure the file is empty since we exclude
1026 * attempts to extend the root directory above, and the root
1027 * dir is the only file with a startcluster of 0 that has
1028 * blocks allocated (sort of).
1029 */
1030 if (dep->de_StartCluster == 0)
1031 cn = 0;
1032 else
1033 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1;
1034 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got);
1035 if (error)
1036 return (error);
1037
1038 count -= got;
1039
1040 /*
1041 * Give them the filesystem relative cluster number if they want
1042 * it.
1043 */
1044 if (ncp) {
1045 *ncp = cn;
1046 ncp = NULL;
1047 }
1048
1049 if (dep->de_StartCluster == 0) {
1050 dep->de_StartCluster = cn;
1051 frcn = 0;
1052 } else {
1053 error = fatentry(FAT_SET, pmp,
1054 dep->de_fc[FC_LASTFC].fc_fsrcn,
1055 0, cn);
1056 if (error) {
1057 clusterfree(pmp, cn);
1058 return (error);
1059 }
1060 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1;
1061 }
1062
1063 /*
1064 * Update the "last cluster of the file" entry in the
1065 * denode's FAT cache.
1066 */
1067 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1);
1068
1069 if (flags & DE_CLEAR) {
1070 while (got-- > 0) {
1071 /*
1072 * Get the buf header for the new block of the file.
1073 */
1074 if (dep->de_Attributes & ATTR_DIRECTORY)
1075 bp = getblk(pmp->pm_devvp,
1076 cntobn(pmp, cn++),
1077 pmp->pm_bpcluster, 0, 0, 0);
1078 else {
1079 bp = getblk(DETOV(dep),
1080 frcn++,
1081 pmp->pm_bpcluster, 0, 0, 0);
1082 /*
1083 * Do the bmap now, as in msdosfs_write
1084 */
1085 if (pcbmap(dep,
1086 bp->b_lblkno,
1087 &blkno, 0, 0))
1088 bp->b_blkno = -1;
1089 if (bp->b_blkno == -1)
1090 panic("extendfile: pcbmap");
1091 else
1092 bp->b_blkno = blkno;
1093 }
1094 clrbuf(bp);
1095 if (bpp) {
1096 *bpp = bp;
1097 bpp = NULL;
1098 } else {
1099 bdwrite(bp);
1100 }
1101 if (vm_page_count_severe() ||
1102 buf_dirty_count_severe())
1103 vn_fsync_buf(DETOV(dep), MNT_WAIT);
1104 }
1105 }
1106 }
1107
1108 return (0);
1109 }
1110
1111 /*-
1112 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by
1113 * manipulating the upper bit of the FAT entry for cluster 1. Note that
1114 * this bit is not defined for FAT12 volumes, which are always assumed to
1115 * be clean.
1116 *
1117 * The fatentry() routine only works on cluster numbers that a file could
1118 * occupy, so it won't manipulate the entry for cluster 1. So we have to do
1119 * it here. The code was stolen from fatentry() and tailored for cluster 1.
1120 *
1121 * Inputs:
1122 * pmp The MS-DOS volume to mark
1123 * dirty Non-zero if the volume should be marked dirty; zero if it
1124 * should be marked clean
1125 *
1126 * Result:
1127 * 0 Success
1128 * EROFS Volume is read-only
1129 * ? (other errors from called routines)
1130 */
1131 int
1132 markvoldirty_upgrade(struct msdosfsmount *pmp, bool dirty, bool rw_upgrade)
1133 {
1134 struct buf *bp;
1135 u_long bn, bo, bsize, byteoffset, fatval;
1136 int error;
1137
1138 /*
1139 * FAT12 does not support a "clean" bit, so don't do anything for
1140 * FAT12.
1141 */
1142 if (FAT12(pmp))
1143 return (0);
1144
1145 /*
1146 * Can't change the bit on a read-only filesystem, except as part of
1147 * ro->rw upgrade.
1148 */
1149 if ((pmp->pm_flags & MSDOSFSMNT_RONLY) != 0 && !rw_upgrade)
1150 return (EROFS);
1151
1152 /*
1153 * Fetch the block containing the FAT entry. It is given by the
1154 * pseudo-cluster 1.
1155 */
1156 byteoffset = FATOFS(pmp, 1);
1157 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
1158 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
1159 if (error)
1160 return (error);
1161
1162 /*
1163 * Get the current value of the FAT entry and set/clear the relevant
1164 * bit. Dirty means clear the "clean" bit; clean means set the
1165 * "clean" bit.
1166 */
1167 if (FAT32(pmp)) {
1168 /* FAT32 uses bit 27. */
1169 fatval = getulong(&bp->b_data[bo]);
1170 if (dirty)
1171 fatval &= 0xF7FFFFFF;
1172 else
1173 fatval |= 0x08000000;
1174 putulong(&bp->b_data[bo], fatval);
1175 } else {
1176 /* Must be FAT16; use bit 15. */
1177 fatval = getushort(&bp->b_data[bo]);
1178 if (dirty)
1179 fatval &= 0x7FFF;
1180 else
1181 fatval |= 0x8000;
1182 putushort(&bp->b_data[bo], fatval);
1183 }
1184
1185 /*
1186 * The concern here is that a devvp may be readonly, without reporting
1187 * itself as such through the usual channels. In that case, we'd like
1188 * it if attempting to mount msdosfs rw didn't panic the system.
1189 *
1190 * markvoldirty is invoked as the first write on backing devvps when
1191 * either msdosfs is mounted for the first time, or a ro mount is
1192 * upgraded to rw.
1193 *
1194 * In either event, if a write error occurs dirtying the volume:
1195 * - No user data has been permitted to be written to cache yet.
1196 * - We can abort the high-level operation (mount, or ro->rw) safely.
1197 * - We don't derive any benefit from leaving a zombie dirty buf in
1198 * the cache that can not be cleaned or evicted.
1199 *
1200 * So, mark B_INVALONERR to have bwrite() -> brelse() detect that
1201 * condition and force-invalidate our write to the block if it occurs.
1202 *
1203 * PR 210316 provides more context on the discovery and diagnosis of
1204 * the problem, as well as earlier attempts to solve it.
1205 */
1206 bp->b_flags |= B_INVALONERR;
1207
1208 /* Write out the modified FAT block synchronously. */
1209 return (bwrite(bp));
1210 }
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