1 /* $FreeBSD: releng/8.0/sys/fs/msdosfs/msdosfs_fat.c 182600 2008-09-01 13:18:16Z kib $ */
2 /* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 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/mount.h>
55 #include <sys/vnode.h>
56
57 #include <fs/msdosfs/bpb.h>
58 #include <fs/msdosfs/direntry.h>
59 #include <fs/msdosfs/denode.h>
60 #include <fs/msdosfs/fat.h>
61 #include <fs/msdosfs/msdosfsmount.h>
62
63 /*
64 * Fat cache stats.
65 */
66 static int fc_fileextends; /* # of file extends */
67 static int fc_lfcempty; /* # of time last file cluster cache entry
68 * was empty */
69 static int fc_bmapcalls; /* # of times pcbmap was called */
70
71 #define LMMAX 20
72 static int fc_lmdistance[LMMAX];/* counters for how far off the last
73 * cluster mapped entry was. */
74 static int fc_largedistance; /* off by more than LMMAX */
75
76 static int chainalloc(struct msdosfsmount *pmp, u_long start,
77 u_long count, u_long fillwith, u_long *retcluster,
78 u_long *got);
79 static int chainlength(struct msdosfsmount *pmp, u_long start,
80 u_long count);
81 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp,
82 u_long *sizep, u_long *bop);
83 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count,
84 u_long fillwith);
85 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp,
86 u_long *fsrcnp);
87 static void updatefats(struct msdosfsmount *pmp, struct buf *bp,
88 u_long fatbn);
89 static __inline void
90 usemap_alloc(struct msdosfsmount *pmp, u_long cn);
91 static __inline void
92 usemap_free(struct msdosfsmount *pmp, u_long cn);
93
94 static void
95 fatblock(pmp, ofs, bnp, sizep, bop)
96 struct msdosfsmount *pmp;
97 u_long ofs;
98 u_long *bnp;
99 u_long *sizep;
100 u_long *bop;
101 {
102 u_long bn, size;
103
104 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec;
105 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn)
106 * DEV_BSIZE;
107 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs;
108
109 if (bnp)
110 *bnp = bn;
111 if (sizep)
112 *sizep = size;
113 if (bop)
114 *bop = ofs % pmp->pm_fatblocksize;
115 }
116
117 /*
118 * Map the logical cluster number of a file into a physical disk sector
119 * that is filesystem relative.
120 *
121 * dep - address of denode representing the file of interest
122 * findcn - file relative cluster whose filesystem relative cluster number
123 * and/or block number are/is to be found
124 * bnp - address of where to place the filesystem relative block number.
125 * If this pointer is null then don't return this quantity.
126 * cnp - address of where to place the filesystem relative cluster number.
127 * If this pointer is null then don't return this quantity.
128 *
129 * NOTE: Either bnp or cnp must be non-null.
130 * This function has one side effect. If the requested file relative cluster
131 * is beyond the end of file, then the actual number of clusters in the file
132 * is returned in *cnp. This is useful for determining how long a directory is.
133 * If cnp is null, nothing is returned.
134 */
135 int
136 pcbmap(dep, findcn, bnp, cnp, sp)
137 struct denode *dep;
138 u_long findcn; /* file relative cluster to get */
139 daddr_t *bnp; /* returned filesys relative blk number */
140 u_long *cnp; /* returned cluster number */
141 int *sp; /* returned block size */
142 {
143 int error;
144 u_long i;
145 u_long cn;
146 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */
147 u_long byteoffset;
148 u_long bn;
149 u_long bo;
150 struct buf *bp = NULL;
151 u_long bp_bn = -1;
152 struct msdosfsmount *pmp = dep->de_pmp;
153 u_long bsize;
154
155 fc_bmapcalls++;
156
157 /*
158 * If they don't give us someplace to return a value then don't
159 * bother doing anything.
160 */
161 if (bnp == NULL && cnp == NULL && sp == NULL)
162 return (0);
163
164 cn = dep->de_StartCluster;
165 /*
166 * The "file" that makes up the root directory is contiguous,
167 * permanently allocated, of fixed size, and is not made up of
168 * clusters. If the cluster number is beyond the end of the root
169 * directory, then return the number of clusters in the file.
170 */
171 if (cn == MSDOSFSROOT) {
172 if (dep->de_Attributes & ATTR_DIRECTORY) {
173 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) {
174 if (cnp)
175 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize);
176 return (E2BIG);
177 }
178 if (bnp)
179 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn);
180 if (cnp)
181 *cnp = MSDOSFSROOT;
182 if (sp)
183 *sp = min(pmp->pm_bpcluster,
184 dep->de_FileSize - de_cn2off(pmp, findcn));
185 return (0);
186 } else { /* just an empty file */
187 if (cnp)
188 *cnp = 0;
189 return (E2BIG);
190 }
191 }
192
193 /*
194 * All other files do I/O in cluster sized blocks
195 */
196 if (sp)
197 *sp = pmp->pm_bpcluster;
198
199 /*
200 * Rummage around in the fat cache, maybe we can avoid tromping
201 * thru every fat entry for the file. And, keep track of how far
202 * off the cache was from where we wanted to be.
203 */
204 i = 0;
205 fc_lookup(dep, findcn, &i, &cn);
206 if ((bn = findcn - i) >= LMMAX)
207 fc_largedistance++;
208 else
209 fc_lmdistance[bn]++;
210
211 /*
212 * Handle all other files or directories the normal way.
213 */
214 for (; i < findcn; i++) {
215 /*
216 * Stop with all reserved clusters, not just with EOF.
217 */
218 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
219 goto hiteof;
220 byteoffset = FATOFS(pmp, cn);
221 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
222 if (bn != bp_bn) {
223 if (bp)
224 brelse(bp);
225 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
226 if (error) {
227 brelse(bp);
228 return (error);
229 }
230 bp_bn = bn;
231 }
232 prevcn = cn;
233 if (bo >= bsize) {
234 if (bp)
235 brelse(bp);
236 return (EIO);
237 }
238 if (FAT32(pmp))
239 cn = getulong(&bp->b_data[bo]);
240 else
241 cn = getushort(&bp->b_data[bo]);
242 if (FAT12(pmp) && (prevcn & 1))
243 cn >>= 4;
244 cn &= pmp->pm_fatmask;
245
246 /*
247 * Force the special cluster numbers
248 * to be the same for all cluster sizes
249 * to let the rest of msdosfs handle
250 * all cases the same.
251 */
252 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
253 cn |= ~pmp->pm_fatmask;
254 }
255
256 if (!MSDOSFSEOF(pmp, cn)) {
257 if (bp)
258 brelse(bp);
259 if (bnp)
260 *bnp = cntobn(pmp, cn);
261 if (cnp)
262 *cnp = cn;
263 fc_setcache(dep, FC_LASTMAP, i, cn);
264 return (0);
265 }
266
267 hiteof:;
268 if (cnp)
269 *cnp = i;
270 if (bp)
271 brelse(bp);
272 /* update last file cluster entry in the fat cache */
273 fc_setcache(dep, FC_LASTFC, i - 1, prevcn);
274 return (E2BIG);
275 }
276
277 /*
278 * Find the closest entry in the fat cache to the cluster we are looking
279 * for.
280 */
281 static void
282 fc_lookup(dep, findcn, frcnp, fsrcnp)
283 struct denode *dep;
284 u_long findcn;
285 u_long *frcnp;
286 u_long *fsrcnp;
287 {
288 int i;
289 u_long cn;
290 struct fatcache *closest = 0;
291
292 for (i = 0; i < FC_SIZE; i++) {
293 cn = dep->de_fc[i].fc_frcn;
294 if (cn != FCE_EMPTY && cn <= findcn) {
295 if (closest == 0 || cn > closest->fc_frcn)
296 closest = &dep->de_fc[i];
297 }
298 }
299 if (closest) {
300 *frcnp = closest->fc_frcn;
301 *fsrcnp = closest->fc_fsrcn;
302 }
303 }
304
305 /*
306 * Purge the fat cache in denode dep of all entries relating to file
307 * relative cluster frcn and beyond.
308 */
309 void
310 fc_purge(dep, frcn)
311 struct denode *dep;
312 u_int frcn;
313 {
314 int i;
315 struct fatcache *fcp;
316
317 fcp = dep->de_fc;
318 for (i = 0; i < FC_SIZE; i++, fcp++) {
319 if (fcp->fc_frcn >= frcn)
320 fcp->fc_frcn = FCE_EMPTY;
321 }
322 }
323
324 /*
325 * Update the fat.
326 * If mirroring the fat, update all copies, with the first copy as last.
327 * Else update only the current fat (ignoring the others).
328 *
329 * pmp - msdosfsmount structure for filesystem to update
330 * bp - addr of modified fat block
331 * fatbn - block number relative to begin of filesystem of the modified fat block.
332 */
333 static void
334 updatefats(pmp, bp, fatbn)
335 struct msdosfsmount *pmp;
336 struct buf *bp;
337 u_long fatbn;
338 {
339 int i;
340 struct buf *bpn;
341
342 #ifdef MSDOSFS_DEBUG
343 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn);
344 #endif
345
346 /*
347 * If we have an FSInfo block, update it.
348 */
349 if (pmp->pm_fsinfo) {
350 if (bread(pmp->pm_devvp, pmp->pm_fsinfo, pmp->pm_BytesPerSec,
351 NOCRED, &bpn) != 0) {
352 /*
353 * Ignore the error, but turn off FSInfo update for the future.
354 */
355 pmp->pm_fsinfo = 0;
356 brelse(bpn);
357 } else {
358 struct fsinfo *fp = (struct fsinfo *)bpn->b_data;
359
360 putulong(fp->fsinfree, pmp->pm_freeclustercount);
361 putulong(fp->fsinxtfree, pmp->pm_nxtfree);
362 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT)
363 bwrite(bpn);
364 else
365 bdwrite(bpn);
366 }
367 }
368
369 if (pmp->pm_flags & MSDOSFS_FATMIRROR) {
370 /*
371 * Now copy the block(s) of the modified fat to the other copies of
372 * the fat and write them out. This is faster than reading in the
373 * other fats and then writing them back out. This could tie up
374 * the fat for quite a while. Preventing others from accessing it.
375 * To prevent us from going after the fat quite so much we use
376 * delayed writes, unless they specfied "synchronous" when the
377 * filesystem was mounted. If synch is asked for then use
378 * bwrite()'s and really slow things down.
379 */
380 for (i = 1; i < pmp->pm_FATs; i++) {
381 fatbn += pmp->pm_FATsecs;
382 /* getblk() never fails */
383 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount,
384 0, 0, 0);
385 bcopy(bp->b_data, bpn->b_data, bp->b_bcount);
386 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT)
387 bwrite(bpn);
388 else
389 bdwrite(bpn);
390 }
391 }
392
393 /*
394 * Write out the first (or current) fat last.
395 */
396 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT)
397 bwrite(bp);
398 else
399 bdwrite(bp);
400 /*
401 * Maybe update fsinfo sector here?
402 */
403 }
404
405 /*
406 * Updating entries in 12 bit fats is a pain in the butt.
407 *
408 * The following picture shows where nibbles go when moving from a 12 bit
409 * cluster number into the appropriate bytes in the FAT.
410 *
411 * byte m byte m+1 byte m+2
412 * +----+----+ +----+----+ +----+----+
413 * | 0 1 | | 2 3 | | 4 5 | FAT bytes
414 * +----+----+ +----+----+ +----+----+
415 *
416 * +----+----+----+ +----+----+----+
417 * | 3 0 1 | | 4 5 2 |
418 * +----+----+----+ +----+----+----+
419 * cluster n cluster n+1
420 *
421 * Where n is even. m = n + (n >> 2)
422 *
423 */
424 static __inline void
425 usemap_alloc(pmp, cn)
426 struct msdosfsmount *pmp;
427 u_long cn;
428 {
429
430 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS);
431 pmp->pm_freeclustercount--;
432 }
433
434 static __inline void
435 usemap_free(pmp, cn)
436 struct msdosfsmount *pmp;
437 u_long cn;
438 {
439
440 pmp->pm_freeclustercount++;
441 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS));
442 }
443
444 int
445 clusterfree(pmp, cluster, oldcnp)
446 struct msdosfsmount *pmp;
447 u_long cluster;
448 u_long *oldcnp;
449 {
450 int error;
451 u_long oldcn;
452
453 usemap_free(pmp, cluster);
454 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE);
455 if (error) {
456 usemap_alloc(pmp, cluster);
457 return (error);
458 }
459 /*
460 * If the cluster was successfully marked free, then update
461 * the count of free clusters, and turn off the "allocated"
462 * bit in the "in use" cluster bit map.
463 */
464 if (oldcnp)
465 *oldcnp = oldcn;
466 return (0);
467 }
468
469 /*
470 * Get or Set or 'Get and Set' the cluster'th entry in the fat.
471 *
472 * function - whether to get or set a fat entry
473 * pmp - address of the msdosfsmount structure for the filesystem
474 * whose fat is to be manipulated.
475 * cn - which cluster is of interest
476 * oldcontents - address of a word that is to receive the contents of the
477 * cluster'th entry if this is a get function
478 * newcontents - the new value to be written into the cluster'th element of
479 * the fat if this is a set function.
480 *
481 * This function can also be used to free a cluster by setting the fat entry
482 * for a cluster to 0.
483 *
484 * All copies of the fat are updated if this is a set function. NOTE: If
485 * fatentry() marks a cluster as free it does not update the inusemap in
486 * the msdosfsmount structure. This is left to the caller.
487 */
488 int
489 fatentry(function, pmp, cn, oldcontents, newcontents)
490 int function;
491 struct msdosfsmount *pmp;
492 u_long cn;
493 u_long *oldcontents;
494 u_long newcontents;
495 {
496 int error;
497 u_long readcn;
498 u_long bn, bo, bsize, byteoffset;
499 struct buf *bp;
500
501 #ifdef MSDOSFS_DEBUG
502 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n",
503 function, pmp, cn, oldcontents, newcontents);
504 #endif
505
506 #ifdef DIAGNOSTIC
507 /*
508 * Be sure they asked us to do something.
509 */
510 if ((function & (FAT_SET | FAT_GET)) == 0) {
511 printf("fatentry(): function code doesn't specify get or set\n");
512 return (EINVAL);
513 }
514
515 /*
516 * If they asked us to return a cluster number but didn't tell us
517 * where to put it, give them an error.
518 */
519 if ((function & FAT_GET) && oldcontents == NULL) {
520 printf("fatentry(): get function with no place to put result\n");
521 return (EINVAL);
522 }
523 #endif
524
525 /*
526 * Be sure the requested cluster is in the filesystem.
527 */
528 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster)
529 return (EINVAL);
530
531 byteoffset = FATOFS(pmp, cn);
532 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
533 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
534 if (error) {
535 brelse(bp);
536 return (error);
537 }
538
539 if (function & FAT_GET) {
540 if (FAT32(pmp))
541 readcn = getulong(&bp->b_data[bo]);
542 else
543 readcn = getushort(&bp->b_data[bo]);
544 if (FAT12(pmp) & (cn & 1))
545 readcn >>= 4;
546 readcn &= pmp->pm_fatmask;
547 /* map reserved fat entries to same values for all fats */
548 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
549 readcn |= ~pmp->pm_fatmask;
550 *oldcontents = readcn;
551 }
552 if (function & FAT_SET) {
553 switch (pmp->pm_fatmask) {
554 case FAT12_MASK:
555 readcn = getushort(&bp->b_data[bo]);
556 if (cn & 1) {
557 readcn &= 0x000f;
558 readcn |= newcontents << 4;
559 } else {
560 readcn &= 0xf000;
561 readcn |= newcontents & 0xfff;
562 }
563 putushort(&bp->b_data[bo], readcn);
564 break;
565 case FAT16_MASK:
566 putushort(&bp->b_data[bo], newcontents);
567 break;
568 case FAT32_MASK:
569 /*
570 * According to spec we have to retain the
571 * high order bits of the fat entry.
572 */
573 readcn = getulong(&bp->b_data[bo]);
574 readcn &= ~FAT32_MASK;
575 readcn |= newcontents & FAT32_MASK;
576 putulong(&bp->b_data[bo], readcn);
577 break;
578 }
579 updatefats(pmp, bp, bn);
580 bp = NULL;
581 pmp->pm_fmod = 1;
582 }
583 if (bp)
584 brelse(bp);
585 return (0);
586 }
587
588 /*
589 * Update a contiguous cluster chain
590 *
591 * pmp - mount point
592 * start - first cluster of chain
593 * count - number of clusters in chain
594 * fillwith - what to write into fat entry of last cluster
595 */
596 static int
597 fatchain(pmp, start, count, fillwith)
598 struct msdosfsmount *pmp;
599 u_long start;
600 u_long count;
601 u_long fillwith;
602 {
603 int error;
604 u_long bn, bo, bsize, byteoffset, readcn, newc;
605 struct buf *bp;
606
607 #ifdef MSDOSFS_DEBUG
608 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n",
609 pmp, start, count, fillwith);
610 #endif
611 /*
612 * Be sure the clusters are in the filesystem.
613 */
614 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster)
615 return (EINVAL);
616
617 while (count > 0) {
618 byteoffset = FATOFS(pmp, start);
619 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
620 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
621 if (error) {
622 brelse(bp);
623 return (error);
624 }
625 while (count > 0) {
626 start++;
627 newc = --count > 0 ? start : fillwith;
628 switch (pmp->pm_fatmask) {
629 case FAT12_MASK:
630 readcn = getushort(&bp->b_data[bo]);
631 if (start & 1) {
632 readcn &= 0xf000;
633 readcn |= newc & 0xfff;
634 } else {
635 readcn &= 0x000f;
636 readcn |= newc << 4;
637 }
638 putushort(&bp->b_data[bo], readcn);
639 bo++;
640 if (!(start & 1))
641 bo++;
642 break;
643 case FAT16_MASK:
644 putushort(&bp->b_data[bo], newc);
645 bo += 2;
646 break;
647 case FAT32_MASK:
648 readcn = getulong(&bp->b_data[bo]);
649 readcn &= ~pmp->pm_fatmask;
650 readcn |= newc & pmp->pm_fatmask;
651 putulong(&bp->b_data[bo], readcn);
652 bo += 4;
653 break;
654 }
655 if (bo >= bsize)
656 break;
657 }
658 updatefats(pmp, bp, bn);
659 }
660 pmp->pm_fmod = 1;
661 return (0);
662 }
663
664 /*
665 * Check the length of a free cluster chain starting at start.
666 *
667 * pmp - mount point
668 * start - start of chain
669 * count - maximum interesting length
670 */
671 static int
672 chainlength(pmp, start, count)
673 struct msdosfsmount *pmp;
674 u_long start;
675 u_long count;
676 {
677 u_long idx, max_idx;
678 u_int map;
679 u_long len;
680
681 max_idx = pmp->pm_maxcluster / N_INUSEBITS;
682 idx = start / N_INUSEBITS;
683 start %= N_INUSEBITS;
684 map = pmp->pm_inusemap[idx];
685 map &= ~((1 << start) - 1);
686 if (map) {
687 len = ffs(map) - 1 - start;
688 return (len > count ? count : len);
689 }
690 len = N_INUSEBITS - start;
691 if (len >= count)
692 return (count);
693 while (++idx <= max_idx) {
694 if (len >= count)
695 break;
696 map = pmp->pm_inusemap[idx];
697 if (map) {
698 len += ffs(map) - 1;
699 break;
700 }
701 len += N_INUSEBITS;
702 }
703 return (len > count ? count : len);
704 }
705
706 /*
707 * Allocate contigous free clusters.
708 *
709 * pmp - mount point.
710 * start - start of cluster chain.
711 * count - number of clusters to allocate.
712 * fillwith - put this value into the fat entry for the
713 * last allocated cluster.
714 * retcluster - put the first allocated cluster's number here.
715 * got - how many clusters were actually allocated.
716 */
717 static int
718 chainalloc(pmp, start, count, fillwith, retcluster, got)
719 struct msdosfsmount *pmp;
720 u_long start;
721 u_long count;
722 u_long fillwith;
723 u_long *retcluster;
724 u_long *got;
725 {
726 int error;
727 u_long cl, n;
728
729 for (cl = start, n = count; n-- > 0;)
730 usemap_alloc(pmp, cl++);
731
732 error = fatchain(pmp, start, count, fillwith);
733 if (error != 0)
734 return (error);
735 #ifdef MSDOSFS_DEBUG
736 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n",
737 start, count);
738 #endif
739 if (retcluster)
740 *retcluster = start;
741 if (got)
742 *got = count;
743 pmp->pm_nxtfree = start + count;
744 if (pmp->pm_nxtfree > pmp->pm_maxcluster)
745 pmp->pm_nxtfree = CLUST_FIRST;
746 return (0);
747 }
748
749 /*
750 * Allocate contiguous free clusters.
751 *
752 * pmp - mount point.
753 * start - preferred start of cluster chain.
754 * count - number of clusters requested.
755 * fillwith - put this value into the fat entry for the
756 * last allocated cluster.
757 * retcluster - put the first allocated cluster's number here.
758 * got - how many clusters were actually allocated.
759 */
760 int
761 clusteralloc(pmp, start, count, fillwith, retcluster, got)
762 struct msdosfsmount *pmp;
763 u_long start;
764 u_long count;
765 u_long fillwith;
766 u_long *retcluster;
767 u_long *got;
768 {
769 u_long idx;
770 u_long len, newst, foundl, cn, l;
771 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */
772 u_int map;
773
774 #ifdef MSDOSFS_DEBUG
775 printf("clusteralloc(): find %lu clusters\n", count);
776 #endif
777 if (start) {
778 if ((len = chainlength(pmp, start, count)) >= count)
779 return (chainalloc(pmp, start, count, fillwith, retcluster, got));
780 } else
781 len = 0;
782
783 newst = pmp->pm_nxtfree;
784 foundl = 0;
785
786 for (cn = newst; cn <= pmp->pm_maxcluster;) {
787 idx = cn / N_INUSEBITS;
788 map = pmp->pm_inusemap[idx];
789 map |= (1 << (cn % N_INUSEBITS)) - 1;
790 if (map != (u_int)-1) {
791 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
792 if ((l = chainlength(pmp, cn, count)) >= count)
793 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
794 if (l > foundl) {
795 foundcn = cn;
796 foundl = l;
797 }
798 cn += l + 1;
799 continue;
800 }
801 cn += N_INUSEBITS - cn % N_INUSEBITS;
802 }
803 for (cn = 0; cn < newst;) {
804 idx = cn / N_INUSEBITS;
805 map = pmp->pm_inusemap[idx];
806 map |= (1 << (cn % N_INUSEBITS)) - 1;
807 if (map != (u_int)-1) {
808 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
809 if ((l = chainlength(pmp, cn, count)) >= count)
810 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
811 if (l > foundl) {
812 foundcn = cn;
813 foundl = l;
814 }
815 cn += l + 1;
816 continue;
817 }
818 cn += N_INUSEBITS - cn % N_INUSEBITS;
819 }
820
821 if (!foundl)
822 return (ENOSPC);
823
824 if (len)
825 return (chainalloc(pmp, start, len, fillwith, retcluster, got));
826 else
827 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got));
828 }
829
830
831 /*
832 * Free a chain of clusters.
833 *
834 * pmp - address of the msdosfs mount structure for the filesystem
835 * containing the cluster chain to be freed.
836 * startcluster - number of the 1st cluster in the chain of clusters to be
837 * freed.
838 */
839 int
840 freeclusterchain(pmp, cluster)
841 struct msdosfsmount *pmp;
842 u_long cluster;
843 {
844 int error;
845 struct buf *bp = NULL;
846 u_long bn, bo, bsize, byteoffset;
847 u_long readcn, lbn = -1;
848
849 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) {
850 byteoffset = FATOFS(pmp, cluster);
851 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
852 if (lbn != bn) {
853 if (bp)
854 updatefats(pmp, bp, lbn);
855 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
856 if (error) {
857 brelse(bp);
858 return (error);
859 }
860 lbn = bn;
861 }
862 usemap_free(pmp, cluster);
863 switch (pmp->pm_fatmask) {
864 case FAT12_MASK:
865 readcn = getushort(&bp->b_data[bo]);
866 if (cluster & 1) {
867 cluster = readcn >> 4;
868 readcn &= 0x000f;
869 readcn |= MSDOSFSFREE << 4;
870 } else {
871 cluster = readcn;
872 readcn &= 0xf000;
873 readcn |= MSDOSFSFREE & 0xfff;
874 }
875 putushort(&bp->b_data[bo], readcn);
876 break;
877 case FAT16_MASK:
878 cluster = getushort(&bp->b_data[bo]);
879 putushort(&bp->b_data[bo], MSDOSFSFREE);
880 break;
881 case FAT32_MASK:
882 cluster = getulong(&bp->b_data[bo]);
883 putulong(&bp->b_data[bo],
884 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK));
885 break;
886 }
887 cluster &= pmp->pm_fatmask;
888 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD)
889 cluster |= pmp->pm_fatmask;
890 }
891 if (bp)
892 updatefats(pmp, bp, bn);
893 return (0);
894 }
895
896 /*
897 * Read in fat blocks looking for free clusters. For every free cluster
898 * found turn off its corresponding bit in the pm_inusemap.
899 */
900 int
901 fillinusemap(pmp)
902 struct msdosfsmount *pmp;
903 {
904 struct buf *bp = NULL;
905 u_long cn, readcn;
906 int error;
907 u_long bn, bo, bsize, byteoffset;
908
909 /*
910 * Mark all clusters in use, we mark the free ones in the fat scan
911 * loop further down.
912 */
913 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++)
914 pmp->pm_inusemap[cn] = (u_int)-1;
915
916 /*
917 * Figure how many free clusters are in the filesystem by ripping
918 * through the fat counting the number of entries whose content is
919 * zero. These represent free clusters.
920 */
921 pmp->pm_freeclustercount = 0;
922 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) {
923 byteoffset = FATOFS(pmp, cn);
924 bo = byteoffset % pmp->pm_fatblocksize;
925 if (!bo || !bp) {
926 /* Read new FAT block */
927 if (bp)
928 brelse(bp);
929 fatblock(pmp, byteoffset, &bn, &bsize, NULL);
930 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
931 if (error) {
932 brelse(bp);
933 return (error);
934 }
935 }
936 if (FAT32(pmp))
937 readcn = getulong(&bp->b_data[bo]);
938 else
939 readcn = getushort(&bp->b_data[bo]);
940 if (FAT12(pmp) && (cn & 1))
941 readcn >>= 4;
942 readcn &= pmp->pm_fatmask;
943
944 if (readcn == 0)
945 usemap_free(pmp, cn);
946 }
947 brelse(bp);
948 return (0);
949 }
950
951 /*
952 * Allocate a new cluster and chain it onto the end of the file.
953 *
954 * dep - the file to extend
955 * count - number of clusters to allocate
956 * bpp - where to return the address of the buf header for the first new
957 * file block
958 * ncp - where to put cluster number of the first newly allocated cluster
959 * If this pointer is 0, do not return the cluster number.
960 * flags - see fat.h
961 *
962 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of
963 * the de_flag field of the denode and it does not change the de_FileSize
964 * field. This is left for the caller to do.
965 */
966 int
967 extendfile(dep, count, bpp, ncp, flags)
968 struct denode *dep;
969 u_long count;
970 struct buf **bpp;
971 u_long *ncp;
972 int flags;
973 {
974 int error;
975 u_long frcn;
976 u_long cn, got;
977 struct msdosfsmount *pmp = dep->de_pmp;
978 struct buf *bp;
979 daddr_t blkno;
980
981 /*
982 * Don't try to extend the root directory
983 */
984 if (dep->de_StartCluster == MSDOSFSROOT
985 && (dep->de_Attributes & ATTR_DIRECTORY)) {
986 printf("extendfile(): attempt to extend root directory\n");
987 return (ENOSPC);
988 }
989
990 /*
991 * If the "file's last cluster" cache entry is empty, and the file
992 * is not empty, then fill the cache entry by calling pcbmap().
993 */
994 fc_fileextends++;
995 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY &&
996 dep->de_StartCluster != 0) {
997 fc_lfcempty++;
998 error = pcbmap(dep, 0xffff, 0, &cn, 0);
999 /* we expect it to return E2BIG */
1000 if (error != E2BIG)
1001 return (error);
1002 }
1003
1004 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn =
1005 dep->de_fc[FC_LASTFC].fc_frcn;
1006 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn =
1007 dep->de_fc[FC_LASTFC].fc_fsrcn;
1008 while (count > 0) {
1009 /*
1010 * Allocate a new cluster chain and cat onto the end of the
1011 * file. * If the file is empty we make de_StartCluster point
1012 * to the new block. Note that de_StartCluster being 0 is
1013 * sufficient to be sure the file is empty since we exclude
1014 * attempts to extend the root directory above, and the root
1015 * dir is the only file with a startcluster of 0 that has
1016 * blocks allocated (sort of).
1017 */
1018 if (dep->de_StartCluster == 0)
1019 cn = 0;
1020 else
1021 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1;
1022 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got);
1023 if (error)
1024 return (error);
1025
1026 count -= got;
1027
1028 /*
1029 * Give them the filesystem relative cluster number if they want
1030 * it.
1031 */
1032 if (ncp) {
1033 *ncp = cn;
1034 ncp = NULL;
1035 }
1036
1037 if (dep->de_StartCluster == 0) {
1038 dep->de_StartCluster = cn;
1039 frcn = 0;
1040 } else {
1041 error = fatentry(FAT_SET, pmp,
1042 dep->de_fc[FC_LASTFC].fc_fsrcn,
1043 0, cn);
1044 if (error) {
1045 clusterfree(pmp, cn, NULL);
1046 return (error);
1047 }
1048 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1;
1049 }
1050
1051 /*
1052 * Update the "last cluster of the file" entry in the denode's fat
1053 * cache.
1054 */
1055 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1);
1056
1057 if (flags & DE_CLEAR) {
1058 while (got-- > 0) {
1059 /*
1060 * Get the buf header for the new block of the file.
1061 */
1062 if (dep->de_Attributes & ATTR_DIRECTORY)
1063 bp = getblk(pmp->pm_devvp,
1064 cntobn(pmp, cn++),
1065 pmp->pm_bpcluster, 0, 0, 0);
1066 else {
1067 bp = getblk(DETOV(dep),
1068 frcn++,
1069 pmp->pm_bpcluster, 0, 0, 0);
1070 /*
1071 * Do the bmap now, as in msdosfs_write
1072 */
1073 if (pcbmap(dep,
1074 bp->b_lblkno,
1075 &blkno, 0, 0))
1076 bp->b_blkno = -1;
1077 if (bp->b_blkno == -1)
1078 panic("extendfile: pcbmap");
1079 else
1080 bp->b_blkno = blkno;
1081 }
1082 vfs_bio_clrbuf(bp);
1083 if (bpp) {
1084 *bpp = bp;
1085 bpp = NULL;
1086 } else
1087 bdwrite(bp);
1088 }
1089 }
1090 }
1091
1092 return (0);
1093 }
1094
1095 /*-
1096 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by
1097 * manipulating the upper bit of the FAT entry for cluster 1. Note that
1098 * this bit is not defined for FAT12 volumes, which are always assumed to
1099 * be dirty.
1100 *
1101 * The fatentry() routine only works on cluster numbers that a file could
1102 * occupy, so it won't manipulate the entry for cluster 1. So we have to do
1103 * it here. The code was stolen from fatentry() and tailored for cluster 1.
1104 *
1105 * Inputs:
1106 * pmp The MS-DOS volume to mark
1107 * dirty Non-zero if the volume should be marked dirty; zero if it
1108 * should be marked clean
1109 *
1110 * Result:
1111 * 0 Success
1112 * EROFS Volume is read-only
1113 * ? (other errors from called routines)
1114 */
1115 int
1116 markvoldirty(struct msdosfsmount *pmp, int dirty)
1117 {
1118 struct buf *bp;
1119 u_long bn, bo, bsize, byteoffset, fatval;
1120 int error;
1121
1122 /*
1123 * FAT12 does not support a "clean" bit, so don't do anything for
1124 * FAT12.
1125 */
1126 if (FAT12(pmp))
1127 return (0);
1128
1129 /* Can't change the bit on a read-only filesystem. */
1130 if (pmp->pm_flags & MSDOSFSMNT_RONLY)
1131 return (EROFS);
1132
1133 /*
1134 * Fetch the block containing the FAT entry. It is given by the
1135 * pseudo-cluster 1.
1136 */
1137 byteoffset = FATOFS(pmp, 1);
1138 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
1139 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
1140 if (error) {
1141 brelse(bp);
1142 return (error);
1143 }
1144
1145 /*
1146 * Get the current value of the FAT entry and set/clear the relevant
1147 * bit. Dirty means clear the "clean" bit; clean means set the
1148 * "clean" bit.
1149 */
1150 if (FAT32(pmp)) {
1151 /* FAT32 uses bit 27. */
1152 fatval = getulong(&bp->b_data[bo]);
1153 if (dirty)
1154 fatval &= 0xF7FFFFFF;
1155 else
1156 fatval |= 0x08000000;
1157 putulong(&bp->b_data[bo], fatval);
1158 } else {
1159 /* Must be FAT16; use bit 15. */
1160 fatval = getushort(&bp->b_data[bo]);
1161 if (dirty)
1162 fatval &= 0x7FFF;
1163 else
1164 fatval |= 0x8000;
1165 putushort(&bp->b_data[bo], fatval);
1166 }
1167
1168 /* Write out the modified FAT block synchronously. */
1169 return (bwrite(bp));
1170 }
Cache object: 31bbc128159c4fc19327390c33a18c5a
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