1 /* $FreeBSD: releng/6.1/sys/fs/msdosfs/msdosfs_fat.c 139776 2005-01-06 18:10:42Z imp $ */
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 /*
52 * kernel include files.
53 */
54 #include <sys/param.h>
55 #include <sys/systm.h>
56 #include <sys/bio.h>
57 #include <sys/buf.h>
58 #include <sys/mount.h> /* to define statfs structure */
59 #include <sys/vnode.h> /* to define vattr structure */
60
61 /*
62 * msdosfs include files.
63 */
64 #include <fs/msdosfs/bpb.h>
65 #include <fs/msdosfs/msdosfsmount.h>
66 #include <fs/msdosfs/direntry.h>
67 #include <fs/msdosfs/denode.h>
68 #include <fs/msdosfs/fat.h>
69
70 /*
71 * Fat cache stats.
72 */
73 static int fc_fileextends; /* # of file extends */
74 static int fc_lfcempty; /* # of time last file cluster cache entry
75 * was empty */
76 static int fc_bmapcalls; /* # of times pcbmap was called */
77
78 #define LMMAX 20
79 static int fc_lmdistance[LMMAX];/* counters for how far off the last
80 * cluster mapped entry was. */
81 static int fc_largedistance; /* off by more than LMMAX */
82
83 static int chainalloc(struct msdosfsmount *pmp, u_long start,
84 u_long count, u_long fillwith, u_long *retcluster,
85 u_long *got);
86 static int chainlength(struct msdosfsmount *pmp, u_long start,
87 u_long count);
88 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp,
89 u_long *sizep, u_long *bop);
90 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count,
91 u_long fillwith);
92 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp,
93 u_long *fsrcnp);
94 static void updatefats(struct msdosfsmount *pmp, struct buf *bp,
95 u_long fatbn);
96 static __inline void
97 usemap_alloc(struct msdosfsmount *pmp, u_long cn);
98 static __inline void
99 usemap_free(struct msdosfsmount *pmp, u_long cn);
100
101 static void
102 fatblock(pmp, ofs, bnp, sizep, bop)
103 struct msdosfsmount *pmp;
104 u_long ofs;
105 u_long *bnp;
106 u_long *sizep;
107 u_long *bop;
108 {
109 u_long bn, size;
110
111 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec;
112 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn)
113 * DEV_BSIZE;
114 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs;
115
116 if (bnp)
117 *bnp = bn;
118 if (sizep)
119 *sizep = size;
120 if (bop)
121 *bop = ofs % pmp->pm_fatblocksize;
122 }
123
124 /*
125 * Map the logical cluster number of a file into a physical disk sector
126 * that is filesystem relative.
127 *
128 * dep - address of denode representing the file of interest
129 * findcn - file relative cluster whose filesystem relative cluster number
130 * and/or block number are/is to be found
131 * bnp - address of where to place the filesystem relative block number.
132 * If this pointer is null then don't return this quantity.
133 * cnp - address of where to place the filesystem relative cluster number.
134 * If this pointer is null then don't return this quantity.
135 *
136 * NOTE: Either bnp or cnp must be non-null.
137 * This function has one side effect. If the requested file relative cluster
138 * is beyond the end of file, then the actual number of clusters in the file
139 * is returned in *cnp. This is useful for determining how long a directory is.
140 * If cnp is null, nothing is returned.
141 */
142 int
143 pcbmap(dep, findcn, bnp, cnp, sp)
144 struct denode *dep;
145 u_long findcn; /* file relative cluster to get */
146 daddr_t *bnp; /* returned filesys relative blk number */
147 u_long *cnp; /* returned cluster number */
148 int *sp; /* returned block size */
149 {
150 int error;
151 u_long i;
152 u_long cn;
153 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */
154 u_long byteoffset;
155 u_long bn;
156 u_long bo;
157 struct buf *bp = NULL;
158 u_long bp_bn = -1;
159 struct msdosfsmount *pmp = dep->de_pmp;
160 u_long bsize;
161
162 fc_bmapcalls++;
163
164 /*
165 * If they don't give us someplace to return a value then don't
166 * bother doing anything.
167 */
168 if (bnp == NULL && cnp == NULL && sp == NULL)
169 return (0);
170
171 cn = dep->de_StartCluster;
172 /*
173 * The "file" that makes up the root directory is contiguous,
174 * permanently allocated, of fixed size, and is not made up of
175 * clusters. If the cluster number is beyond the end of the root
176 * directory, then return the number of clusters in the file.
177 */
178 if (cn == MSDOSFSROOT) {
179 if (dep->de_Attributes & ATTR_DIRECTORY) {
180 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) {
181 if (cnp)
182 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize);
183 return (E2BIG);
184 }
185 if (bnp)
186 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn);
187 if (cnp)
188 *cnp = MSDOSFSROOT;
189 if (sp)
190 *sp = min(pmp->pm_bpcluster,
191 dep->de_FileSize - de_cn2off(pmp, findcn));
192 return (0);
193 } else { /* just an empty file */
194 if (cnp)
195 *cnp = 0;
196 return (E2BIG);
197 }
198 }
199
200 /*
201 * All other files do I/O in cluster sized blocks
202 */
203 if (sp)
204 *sp = pmp->pm_bpcluster;
205
206 /*
207 * Rummage around in the fat cache, maybe we can avoid tromping
208 * thru every fat entry for the file. And, keep track of how far
209 * off the cache was from where we wanted to be.
210 */
211 i = 0;
212 fc_lookup(dep, findcn, &i, &cn);
213 if ((bn = findcn - i) >= LMMAX)
214 fc_largedistance++;
215 else
216 fc_lmdistance[bn]++;
217
218 /*
219 * Handle all other files or directories the normal way.
220 */
221 for (; i < findcn; i++) {
222 /*
223 * Stop with all reserved clusters, not just with EOF.
224 */
225 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
226 goto hiteof;
227 byteoffset = FATOFS(pmp, cn);
228 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
229 if (bn != bp_bn) {
230 if (bp)
231 brelse(bp);
232 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
233 if (error) {
234 brelse(bp);
235 return (error);
236 }
237 bp_bn = bn;
238 }
239 prevcn = cn;
240 if (bo >= bsize) {
241 if (bp)
242 brelse(bp);
243 return (EIO);
244 }
245 if (FAT32(pmp))
246 cn = getulong(&bp->b_data[bo]);
247 else
248 cn = getushort(&bp->b_data[bo]);
249 if (FAT12(pmp) && (prevcn & 1))
250 cn >>= 4;
251 cn &= pmp->pm_fatmask;
252
253 /*
254 * Force the special cluster numbers
255 * to be the same for all cluster sizes
256 * to let the rest of msdosfs handle
257 * all cases the same.
258 */
259 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
260 cn |= ~pmp->pm_fatmask;
261 }
262
263 if (!MSDOSFSEOF(pmp, cn)) {
264 if (bp)
265 brelse(bp);
266 if (bnp)
267 *bnp = cntobn(pmp, cn);
268 if (cnp)
269 *cnp = cn;
270 fc_setcache(dep, FC_LASTMAP, i, cn);
271 return (0);
272 }
273
274 hiteof:;
275 if (cnp)
276 *cnp = i;
277 if (bp)
278 brelse(bp);
279 /* update last file cluster entry in the fat cache */
280 fc_setcache(dep, FC_LASTFC, i - 1, prevcn);
281 return (E2BIG);
282 }
283
284 /*
285 * Find the closest entry in the fat cache to the cluster we are looking
286 * for.
287 */
288 static void
289 fc_lookup(dep, findcn, frcnp, fsrcnp)
290 struct denode *dep;
291 u_long findcn;
292 u_long *frcnp;
293 u_long *fsrcnp;
294 {
295 int i;
296 u_long cn;
297 struct fatcache *closest = 0;
298
299 for (i = 0; i < FC_SIZE; i++) {
300 cn = dep->de_fc[i].fc_frcn;
301 if (cn != FCE_EMPTY && cn <= findcn) {
302 if (closest == 0 || cn > closest->fc_frcn)
303 closest = &dep->de_fc[i];
304 }
305 }
306 if (closest) {
307 *frcnp = closest->fc_frcn;
308 *fsrcnp = closest->fc_fsrcn;
309 }
310 }
311
312 /*
313 * Purge the fat cache in denode dep of all entries relating to file
314 * relative cluster frcn and beyond.
315 */
316 void
317 fc_purge(dep, frcn)
318 struct denode *dep;
319 u_int frcn;
320 {
321 int i;
322 struct fatcache *fcp;
323
324 fcp = dep->de_fc;
325 for (i = 0; i < FC_SIZE; i++, fcp++) {
326 if (fcp->fc_frcn >= frcn)
327 fcp->fc_frcn = FCE_EMPTY;
328 }
329 }
330
331 /*
332 * Update the fat.
333 * If mirroring the fat, update all copies, with the first copy as last.
334 * Else update only the current fat (ignoring the others).
335 *
336 * pmp - msdosfsmount structure for filesystem to update
337 * bp - addr of modified fat block
338 * fatbn - block number relative to begin of filesystem of the modified fat block.
339 */
340 static void
341 updatefats(pmp, bp, fatbn)
342 struct msdosfsmount *pmp;
343 struct buf *bp;
344 u_long fatbn;
345 {
346 int i;
347 struct buf *bpn;
348
349 #ifdef MSDOSFS_DEBUG
350 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn);
351 #endif
352
353 /*
354 * If we have an FSInfo block, update it.
355 */
356 if (pmp->pm_fsinfo) {
357 u_long cn = pmp->pm_nxtfree;
358
359 if (pmp->pm_freeclustercount
360 && (pmp->pm_inusemap[cn / N_INUSEBITS]
361 & (1 << (cn % N_INUSEBITS)))) {
362 /*
363 * The cluster indicated in FSInfo isn't free
364 * any longer. Got get a new free one.
365 */
366 for (cn = 0; cn < pmp->pm_maxcluster; cn += N_INUSEBITS)
367 if (pmp->pm_inusemap[cn / N_INUSEBITS] != (u_int)-1)
368 break;
369 pmp->pm_nxtfree = cn
370 + ffs(pmp->pm_inusemap[cn / N_INUSEBITS]
371 ^ (u_int)-1) - 1;
372 }
373 if (bread(pmp->pm_devvp, pmp->pm_fsinfo, fsi_size(pmp),
374 NOCRED, &bpn) != 0) {
375 /*
376 * Ignore the error, but turn off FSInfo update for the future.
377 */
378 pmp->pm_fsinfo = 0;
379 brelse(bpn);
380 } else {
381 struct fsinfo *fp = (struct fsinfo *)bpn->b_data;
382
383 putulong(fp->fsinfree, pmp->pm_freeclustercount);
384 putulong(fp->fsinxtfree, pmp->pm_nxtfree);
385 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT)
386 bwrite(bpn);
387 else
388 bdwrite(bpn);
389 }
390 }
391
392 if (pmp->pm_flags & MSDOSFS_FATMIRROR) {
393 /*
394 * Now copy the block(s) of the modified fat to the other copies of
395 * the fat and write them out. This is faster than reading in the
396 * other fats and then writing them back out. This could tie up
397 * the fat for quite a while. Preventing others from accessing it.
398 * To prevent us from going after the fat quite so much we use
399 * delayed writes, unless they specfied "synchronous" when the
400 * filesystem was mounted. If synch is asked for then use
401 * bwrite()'s and really slow things down.
402 */
403 for (i = 1; i < pmp->pm_FATs; i++) {
404 fatbn += pmp->pm_FATsecs;
405 /* getblk() never fails */
406 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount,
407 0, 0, 0);
408 bcopy(bp->b_data, bpn->b_data, bp->b_bcount);
409 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT)
410 bwrite(bpn);
411 else
412 bdwrite(bpn);
413 }
414 }
415
416 /*
417 * Write out the first (or current) fat last.
418 */
419 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT)
420 bwrite(bp);
421 else
422 bdwrite(bp);
423 /*
424 * Maybe update fsinfo sector here?
425 */
426 }
427
428 /*
429 * Updating entries in 12 bit fats is a pain in the butt.
430 *
431 * The following picture shows where nibbles go when moving from a 12 bit
432 * cluster number into the appropriate bytes in the FAT.
433 *
434 * byte m byte m+1 byte m+2
435 * +----+----+ +----+----+ +----+----+
436 * | 0 1 | | 2 3 | | 4 5 | FAT bytes
437 * +----+----+ +----+----+ +----+----+
438 *
439 * +----+----+----+ +----+----+----+
440 * | 3 0 1 | | 4 5 2 |
441 * +----+----+----+ +----+----+----+
442 * cluster n cluster n+1
443 *
444 * Where n is even. m = n + (n >> 2)
445 *
446 */
447 static __inline void
448 usemap_alloc(pmp, cn)
449 struct msdosfsmount *pmp;
450 u_long cn;
451 {
452
453 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS);
454 pmp->pm_freeclustercount--;
455 }
456
457 static __inline void
458 usemap_free(pmp, cn)
459 struct msdosfsmount *pmp;
460 u_long cn;
461 {
462
463 pmp->pm_freeclustercount++;
464 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS));
465 }
466
467 int
468 clusterfree(pmp, cluster, oldcnp)
469 struct msdosfsmount *pmp;
470 u_long cluster;
471 u_long *oldcnp;
472 {
473 int error;
474 u_long oldcn;
475
476 usemap_free(pmp, cluster);
477 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE);
478 if (error) {
479 usemap_alloc(pmp, cluster);
480 return (error);
481 }
482 /*
483 * If the cluster was successfully marked free, then update
484 * the count of free clusters, and turn off the "allocated"
485 * bit in the "in use" cluster bit map.
486 */
487 if (oldcnp)
488 *oldcnp = oldcn;
489 return (0);
490 }
491
492 /*
493 * Get or Set or 'Get and Set' the cluster'th entry in the fat.
494 *
495 * function - whether to get or set a fat entry
496 * pmp - address of the msdosfsmount structure for the filesystem
497 * whose fat is to be manipulated.
498 * cn - which cluster is of interest
499 * oldcontents - address of a word that is to receive the contents of the
500 * cluster'th entry if this is a get function
501 * newcontents - the new value to be written into the cluster'th element of
502 * the fat if this is a set function.
503 *
504 * This function can also be used to free a cluster by setting the fat entry
505 * for a cluster to 0.
506 *
507 * All copies of the fat are updated if this is a set function. NOTE: If
508 * fatentry() marks a cluster as free it does not update the inusemap in
509 * the msdosfsmount structure. This is left to the caller.
510 */
511 int
512 fatentry(function, pmp, cn, oldcontents, newcontents)
513 int function;
514 struct msdosfsmount *pmp;
515 u_long cn;
516 u_long *oldcontents;
517 u_long newcontents;
518 {
519 int error;
520 u_long readcn;
521 u_long bn, bo, bsize, byteoffset;
522 struct buf *bp;
523
524 #ifdef MSDOSFS_DEBUG
525 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n",
526 function, pmp, cn, oldcontents, newcontents);
527 #endif
528
529 #ifdef DIAGNOSTIC
530 /*
531 * Be sure they asked us to do something.
532 */
533 if ((function & (FAT_SET | FAT_GET)) == 0) {
534 printf("fatentry(): function code doesn't specify get or set\n");
535 return (EINVAL);
536 }
537
538 /*
539 * If they asked us to return a cluster number but didn't tell us
540 * where to put it, give them an error.
541 */
542 if ((function & FAT_GET) && oldcontents == NULL) {
543 printf("fatentry(): get function with no place to put result\n");
544 return (EINVAL);
545 }
546 #endif
547
548 /*
549 * Be sure the requested cluster is in the filesystem.
550 */
551 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster)
552 return (EINVAL);
553
554 byteoffset = FATOFS(pmp, cn);
555 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
556 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
557 if (error) {
558 brelse(bp);
559 return (error);
560 }
561
562 if (function & FAT_GET) {
563 if (FAT32(pmp))
564 readcn = getulong(&bp->b_data[bo]);
565 else
566 readcn = getushort(&bp->b_data[bo]);
567 if (FAT12(pmp) & (cn & 1))
568 readcn >>= 4;
569 readcn &= pmp->pm_fatmask;
570 /* map reserved fat entries to same values for all fats */
571 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
572 readcn |= ~pmp->pm_fatmask;
573 *oldcontents = readcn;
574 }
575 if (function & FAT_SET) {
576 switch (pmp->pm_fatmask) {
577 case FAT12_MASK:
578 readcn = getushort(&bp->b_data[bo]);
579 if (cn & 1) {
580 readcn &= 0x000f;
581 readcn |= newcontents << 4;
582 } else {
583 readcn &= 0xf000;
584 readcn |= newcontents & 0xfff;
585 }
586 putushort(&bp->b_data[bo], readcn);
587 break;
588 case FAT16_MASK:
589 putushort(&bp->b_data[bo], newcontents);
590 break;
591 case FAT32_MASK:
592 /*
593 * According to spec we have to retain the
594 * high order bits of the fat entry.
595 */
596 readcn = getulong(&bp->b_data[bo]);
597 readcn &= ~FAT32_MASK;
598 readcn |= newcontents & FAT32_MASK;
599 putulong(&bp->b_data[bo], readcn);
600 break;
601 }
602 updatefats(pmp, bp, bn);
603 bp = NULL;
604 pmp->pm_fmod = 1;
605 }
606 if (bp)
607 brelse(bp);
608 return (0);
609 }
610
611 /*
612 * Update a contiguous cluster chain
613 *
614 * pmp - mount point
615 * start - first cluster of chain
616 * count - number of clusters in chain
617 * fillwith - what to write into fat entry of last cluster
618 */
619 static int
620 fatchain(pmp, start, count, fillwith)
621 struct msdosfsmount *pmp;
622 u_long start;
623 u_long count;
624 u_long fillwith;
625 {
626 int error;
627 u_long bn, bo, bsize, byteoffset, readcn, newc;
628 struct buf *bp;
629
630 #ifdef MSDOSFS_DEBUG
631 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n",
632 pmp, start, count, fillwith);
633 #endif
634 /*
635 * Be sure the clusters are in the filesystem.
636 */
637 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster)
638 return (EINVAL);
639
640 while (count > 0) {
641 byteoffset = FATOFS(pmp, start);
642 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
643 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
644 if (error) {
645 brelse(bp);
646 return (error);
647 }
648 while (count > 0) {
649 start++;
650 newc = --count > 0 ? start : fillwith;
651 switch (pmp->pm_fatmask) {
652 case FAT12_MASK:
653 readcn = getushort(&bp->b_data[bo]);
654 if (start & 1) {
655 readcn &= 0xf000;
656 readcn |= newc & 0xfff;
657 } else {
658 readcn &= 0x000f;
659 readcn |= newc << 4;
660 }
661 putushort(&bp->b_data[bo], readcn);
662 bo++;
663 if (!(start & 1))
664 bo++;
665 break;
666 case FAT16_MASK:
667 putushort(&bp->b_data[bo], newc);
668 bo += 2;
669 break;
670 case FAT32_MASK:
671 readcn = getulong(&bp->b_data[bo]);
672 readcn &= ~pmp->pm_fatmask;
673 readcn |= newc & pmp->pm_fatmask;
674 putulong(&bp->b_data[bo], readcn);
675 bo += 4;
676 break;
677 }
678 if (bo >= bsize)
679 break;
680 }
681 updatefats(pmp, bp, bn);
682 }
683 pmp->pm_fmod = 1;
684 return (0);
685 }
686
687 /*
688 * Check the length of a free cluster chain starting at start.
689 *
690 * pmp - mount point
691 * start - start of chain
692 * count - maximum interesting length
693 */
694 static int
695 chainlength(pmp, start, count)
696 struct msdosfsmount *pmp;
697 u_long start;
698 u_long count;
699 {
700 u_long idx, max_idx;
701 u_int map;
702 u_long len;
703
704 max_idx = pmp->pm_maxcluster / N_INUSEBITS;
705 idx = start / N_INUSEBITS;
706 start %= N_INUSEBITS;
707 map = pmp->pm_inusemap[idx];
708 map &= ~((1 << start) - 1);
709 if (map) {
710 len = ffs(map) - 1 - start;
711 return (len > count ? count : len);
712 }
713 len = N_INUSEBITS - start;
714 if (len >= count)
715 return (count);
716 while (++idx <= max_idx) {
717 if (len >= count)
718 break;
719 map = pmp->pm_inusemap[idx];
720 if (map) {
721 len += ffs(map) - 1;
722 break;
723 }
724 len += N_INUSEBITS;
725 }
726 return (len > count ? count : len);
727 }
728
729 /*
730 * Allocate contigous free clusters.
731 *
732 * pmp - mount point.
733 * start - start of cluster chain.
734 * count - number of clusters to allocate.
735 * fillwith - put this value into the fat entry for the
736 * last allocated cluster.
737 * retcluster - put the first allocated cluster's number here.
738 * got - how many clusters were actually allocated.
739 */
740 static int
741 chainalloc(pmp, start, count, fillwith, retcluster, got)
742 struct msdosfsmount *pmp;
743 u_long start;
744 u_long count;
745 u_long fillwith;
746 u_long *retcluster;
747 u_long *got;
748 {
749 int error;
750 u_long cl, n;
751
752 for (cl = start, n = count; n-- > 0;)
753 usemap_alloc(pmp, cl++);
754
755 error = fatchain(pmp, start, count, fillwith);
756 if (error != 0)
757 return (error);
758 #ifdef MSDOSFS_DEBUG
759 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n",
760 start, count);
761 #endif
762 if (retcluster)
763 *retcluster = start;
764 if (got)
765 *got = count;
766 return (0);
767 }
768
769 /*
770 * Allocate contiguous free clusters.
771 *
772 * pmp - mount point.
773 * start - preferred start of cluster chain.
774 * count - number of clusters requested.
775 * fillwith - put this value into the fat entry for the
776 * last allocated cluster.
777 * retcluster - put the first allocated cluster's number here.
778 * got - how many clusters were actually allocated.
779 */
780 int
781 clusteralloc(pmp, start, count, fillwith, retcluster, got)
782 struct msdosfsmount *pmp;
783 u_long start;
784 u_long count;
785 u_long fillwith;
786 u_long *retcluster;
787 u_long *got;
788 {
789 u_long idx;
790 u_long len, newst, foundl, cn, l;
791 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */
792 u_int map;
793
794 #ifdef MSDOSFS_DEBUG
795 printf("clusteralloc(): find %lu clusters\n",count);
796 #endif
797 if (start) {
798 if ((len = chainlength(pmp, start, count)) >= count)
799 return (chainalloc(pmp, start, count, fillwith, retcluster, got));
800 } else
801 len = 0;
802
803 /*
804 * Start at a (pseudo) random place to maximize cluster runs
805 * under multiple writers.
806 */
807 newst = random() % (pmp->pm_maxcluster + 1);
808 foundl = 0;
809
810 for (cn = newst; cn <= pmp->pm_maxcluster;) {
811 idx = cn / N_INUSEBITS;
812 map = pmp->pm_inusemap[idx];
813 map |= (1 << (cn % N_INUSEBITS)) - 1;
814 if (map != (u_int)-1) {
815 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
816 if ((l = chainlength(pmp, cn, count)) >= count)
817 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
818 if (l > foundl) {
819 foundcn = cn;
820 foundl = l;
821 }
822 cn += l + 1;
823 continue;
824 }
825 cn += N_INUSEBITS - cn % N_INUSEBITS;
826 }
827 for (cn = 0; cn < newst;) {
828 idx = cn / N_INUSEBITS;
829 map = pmp->pm_inusemap[idx];
830 map |= (1 << (cn % N_INUSEBITS)) - 1;
831 if (map != (u_int)-1) {
832 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
833 if ((l = chainlength(pmp, cn, count)) >= count)
834 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
835 if (l > foundl) {
836 foundcn = cn;
837 foundl = l;
838 }
839 cn += l + 1;
840 continue;
841 }
842 cn += N_INUSEBITS - cn % N_INUSEBITS;
843 }
844
845 if (!foundl)
846 return (ENOSPC);
847
848 if (len)
849 return (chainalloc(pmp, start, len, fillwith, retcluster, got));
850 else
851 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got));
852 }
853
854
855 /*
856 * Free a chain of clusters.
857 *
858 * pmp - address of the msdosfs mount structure for the filesystem
859 * containing the cluster chain to be freed.
860 * startcluster - number of the 1st cluster in the chain of clusters to be
861 * freed.
862 */
863 int
864 freeclusterchain(pmp, cluster)
865 struct msdosfsmount *pmp;
866 u_long cluster;
867 {
868 int error;
869 struct buf *bp = NULL;
870 u_long bn, bo, bsize, byteoffset;
871 u_long readcn, lbn = -1;
872
873 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) {
874 byteoffset = FATOFS(pmp, cluster);
875 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
876 if (lbn != bn) {
877 if (bp)
878 updatefats(pmp, bp, lbn);
879 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
880 if (error) {
881 brelse(bp);
882 return (error);
883 }
884 lbn = bn;
885 }
886 usemap_free(pmp, cluster);
887 switch (pmp->pm_fatmask) {
888 case FAT12_MASK:
889 readcn = getushort(&bp->b_data[bo]);
890 if (cluster & 1) {
891 cluster = readcn >> 4;
892 readcn &= 0x000f;
893 readcn |= MSDOSFSFREE << 4;
894 } else {
895 cluster = readcn;
896 readcn &= 0xf000;
897 readcn |= MSDOSFSFREE & 0xfff;
898 }
899 putushort(&bp->b_data[bo], readcn);
900 break;
901 case FAT16_MASK:
902 cluster = getushort(&bp->b_data[bo]);
903 putushort(&bp->b_data[bo], MSDOSFSFREE);
904 break;
905 case FAT32_MASK:
906 cluster = getulong(&bp->b_data[bo]);
907 putulong(&bp->b_data[bo],
908 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK));
909 break;
910 }
911 cluster &= pmp->pm_fatmask;
912 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD)
913 cluster |= pmp->pm_fatmask;
914 }
915 if (bp)
916 updatefats(pmp, bp, bn);
917 return (0);
918 }
919
920 /*
921 * Read in fat blocks looking for free clusters. For every free cluster
922 * found turn off its corresponding bit in the pm_inusemap.
923 */
924 int
925 fillinusemap(pmp)
926 struct msdosfsmount *pmp;
927 {
928 struct buf *bp = NULL;
929 u_long cn, readcn;
930 int error;
931 u_long bn, bo, bsize, byteoffset;
932
933 /*
934 * Mark all clusters in use, we mark the free ones in the fat scan
935 * loop further down.
936 */
937 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++)
938 pmp->pm_inusemap[cn] = (u_int)-1;
939
940 /*
941 * Figure how many free clusters are in the filesystem by ripping
942 * through the fat counting the number of entries whose content is
943 * zero. These represent free clusters.
944 */
945 pmp->pm_freeclustercount = 0;
946 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) {
947 byteoffset = FATOFS(pmp, cn);
948 bo = byteoffset % pmp->pm_fatblocksize;
949 if (!bo || !bp) {
950 /* Read new FAT block */
951 if (bp)
952 brelse(bp);
953 fatblock(pmp, byteoffset, &bn, &bsize, NULL);
954 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
955 if (error) {
956 brelse(bp);
957 return (error);
958 }
959 }
960 if (FAT32(pmp))
961 readcn = getulong(&bp->b_data[bo]);
962 else
963 readcn = getushort(&bp->b_data[bo]);
964 if (FAT12(pmp) && (cn & 1))
965 readcn >>= 4;
966 readcn &= pmp->pm_fatmask;
967
968 if (readcn == 0)
969 usemap_free(pmp, cn);
970 }
971 brelse(bp);
972 return (0);
973 }
974
975 /*
976 * Allocate a new cluster and chain it onto the end of the file.
977 *
978 * dep - the file to extend
979 * count - number of clusters to allocate
980 * bpp - where to return the address of the buf header for the first new
981 * file block
982 * ncp - where to put cluster number of the first newly allocated cluster
983 * If this pointer is 0, do not return the cluster number.
984 * flags - see fat.h
985 *
986 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of
987 * the de_flag field of the denode and it does not change the de_FileSize
988 * field. This is left for the caller to do.
989 */
990 int
991 extendfile(dep, count, bpp, ncp, flags)
992 struct denode *dep;
993 u_long count;
994 struct buf **bpp;
995 u_long *ncp;
996 int flags;
997 {
998 int error;
999 u_long frcn;
1000 u_long cn, got;
1001 struct msdosfsmount *pmp = dep->de_pmp;
1002 struct buf *bp;
1003 daddr_t blkno;
1004
1005 /*
1006 * Don't try to extend the root directory
1007 */
1008 if (dep->de_StartCluster == MSDOSFSROOT
1009 && (dep->de_Attributes & ATTR_DIRECTORY)) {
1010 printf("extendfile(): attempt to extend root directory\n");
1011 return (ENOSPC);
1012 }
1013
1014 /*
1015 * If the "file's last cluster" cache entry is empty, and the file
1016 * is not empty, then fill the cache entry by calling pcbmap().
1017 */
1018 fc_fileextends++;
1019 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY &&
1020 dep->de_StartCluster != 0) {
1021 fc_lfcempty++;
1022 error = pcbmap(dep, 0xffff, 0, &cn, 0);
1023 /* we expect it to return E2BIG */
1024 if (error != E2BIG)
1025 return (error);
1026 }
1027
1028 while (count > 0) {
1029 /*
1030 * Allocate a new cluster chain and cat onto the end of the
1031 * file. * If the file is empty we make de_StartCluster point
1032 * to the new block. Note that de_StartCluster being 0 is
1033 * sufficient to be sure the file is empty since we exclude
1034 * attempts to extend the root directory above, and the root
1035 * dir is the only file with a startcluster of 0 that has
1036 * blocks allocated (sort of).
1037 */
1038 if (dep->de_StartCluster == 0)
1039 cn = 0;
1040 else
1041 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1;
1042 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got);
1043 if (error)
1044 return (error);
1045
1046 count -= got;
1047
1048 /*
1049 * Give them the filesystem relative cluster number if they want
1050 * it.
1051 */
1052 if (ncp) {
1053 *ncp = cn;
1054 ncp = NULL;
1055 }
1056
1057 if (dep->de_StartCluster == 0) {
1058 dep->de_StartCluster = cn;
1059 frcn = 0;
1060 } else {
1061 error = fatentry(FAT_SET, pmp,
1062 dep->de_fc[FC_LASTFC].fc_fsrcn,
1063 0, cn);
1064 if (error) {
1065 clusterfree(pmp, cn, NULL);
1066 return (error);
1067 }
1068 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1;
1069 }
1070
1071 /*
1072 * Update the "last cluster of the file" entry in the denode's fat
1073 * cache.
1074 */
1075 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1);
1076
1077 if (flags & DE_CLEAR) {
1078 while (got-- > 0) {
1079 /*
1080 * Get the buf header for the new block of the file.
1081 */
1082 if (dep->de_Attributes & ATTR_DIRECTORY)
1083 bp = getblk(pmp->pm_devvp,
1084 cntobn(pmp, cn++),
1085 pmp->pm_bpcluster, 0, 0, 0);
1086 else {
1087 bp = getblk(DETOV(dep),
1088 de_cn2bn(pmp, frcn++),
1089 pmp->pm_bpcluster, 0, 0, 0);
1090 /*
1091 * Do the bmap now, as in msdosfs_write
1092 */
1093 if (pcbmap(dep,
1094 de_bn2cn(pmp, bp->b_lblkno),
1095 &blkno, 0, 0))
1096 bp->b_blkno = -1;
1097 if (bp->b_blkno == -1)
1098 panic("extendfile: pcbmap");
1099 else
1100 bp->b_blkno = blkno;
1101 }
1102 clrbuf(bp);
1103 if (bpp) {
1104 *bpp = bp;
1105 bpp = NULL;
1106 } else
1107 bdwrite(bp);
1108 }
1109 }
1110 }
1111
1112 return (0);
1113 }
1114
1115 /*-
1116 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by
1117 * manipulating the upper bit of the FAT entry for cluster 1. Note that
1118 * this bit is not defined for FAT12 volumes, which are always assumed to
1119 * be dirty.
1120 *
1121 * The fatentry() routine only works on cluster numbers that a file could
1122 * occupy, so it won't manipulate the entry for cluster 1. So we have to do
1123 * it here. The code was stolen from fatentry() and tailored for cluster 1.
1124 *
1125 * Inputs:
1126 * pmp The MS-DOS volume to mark
1127 * dirty Non-zero if the volume should be marked dirty; zero if it
1128 * should be marked clean
1129 *
1130 * Result:
1131 * 0 Success
1132 * EROFS Volume is read-only
1133 * ? (other errors from called routines)
1134 */
1135 int
1136 markvoldirty(struct msdosfsmount *pmp, int dirty)
1137 {
1138 struct buf *bp;
1139 u_long bn, bo, bsize, byteoffset, fatval;
1140 int error;
1141
1142 /*
1143 * FAT12 does not support a "clean" bit, so don't do anything for
1144 * FAT12.
1145 */
1146 if (FAT12(pmp))
1147 return (0);
1148
1149 /* Can't change the bit on a read-only filesystem. */
1150 if (pmp->pm_flags & MSDOSFSMNT_RONLY)
1151 return (EROFS);
1152
1153 /*
1154 * Fetch the block containing the FAT entry. It is given by the
1155 * pseudo-cluster 1.
1156 */
1157 byteoffset = FATOFS(pmp, 1);
1158 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
1159 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
1160 if (error) {
1161 brelse(bp);
1162 return (error);
1163 }
1164
1165 /*
1166 * Get the current value of the FAT entry and set/clear the relevant
1167 * bit. Dirty means clear the "clean" bit; clean means set the
1168 * "clean" bit.
1169 */
1170 if (FAT32(pmp)) {
1171 /* FAT32 uses bit 27. */
1172 fatval = getulong(&bp->b_data[bo]);
1173 if (dirty)
1174 fatval &= 0xF7FFFFFF;
1175 else
1176 fatval |= 0x08000000;
1177 putulong(&bp->b_data[bo], fatval);
1178 } else {
1179 /* Must be FAT16; use bit 15. */
1180 fatval = getushort(&bp->b_data[bo]);
1181 if (dirty)
1182 fatval &= 0x7FFF;
1183 else
1184 fatval |= 0x8000;
1185 putushort(&bp->b_data[bo], fatval);
1186 }
1187
1188 /* Write out the modified FAT block synchronously. */
1189 return (bwrite(bp));
1190 }
Cache object: 22b91004028c54f9c178c89fb4902586
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