1 | /* $NetBSD: msdosfs_fat.c,v 1.31 2016/05/07 16:43:02 mlelstv Exp $ */ |
2 | |
3 | /*- |
4 | * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank. |
5 | * Copyright (C) 1994, 1995, 1997 TooLs GmbH. |
6 | * All rights reserved. |
7 | * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below). |
8 | * |
9 | * Redistribution and use in source and binary forms, with or without |
10 | * modification, are permitted provided that the following conditions |
11 | * are met: |
12 | * 1. Redistributions of source code must retain the above copyright |
13 | * notice, this list of conditions and the following disclaimer. |
14 | * 2. Redistributions in binary form must reproduce the above copyright |
15 | * notice, this list of conditions and the following disclaimer in the |
16 | * documentation and/or other materials provided with the distribution. |
17 | * 3. All advertising materials mentioning features or use of this software |
18 | * must display the following acknowledgement: |
19 | * This product includes software developed by TooLs GmbH. |
20 | * 4. The name of TooLs GmbH may not be used to endorse or promote products |
21 | * derived from this software without specific prior written permission. |
22 | * |
23 | * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR |
24 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
25 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
26 | * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
27 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
28 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; |
29 | * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
30 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR |
31 | * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
32 | * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
33 | */ |
34 | /* |
35 | * Written by Paul Popelka (paulp@uts.amdahl.com) |
36 | * |
37 | * You can do anything you want with this software, just don't say you wrote |
38 | * it, and don't remove this notice. |
39 | * |
40 | * This software is provided "as is". |
41 | * |
42 | * The author supplies this software to be publicly redistributed on the |
43 | * understanding that the author is not responsible for the correct |
44 | * functioning of this software in any circumstances and is not liable for |
45 | * any damages caused by this software. |
46 | * |
47 | * October 1992 |
48 | */ |
49 | |
50 | #if HAVE_NBTOOL_CONFIG_H |
51 | #include "nbtool_config.h" |
52 | #endif |
53 | |
54 | #include <sys/cdefs.h> |
55 | __KERNEL_RCSID(0, "$NetBSD: msdosfs_fat.c,v 1.31 2016/05/07 16:43:02 mlelstv Exp $" ); |
56 | |
57 | /* |
58 | * kernel include files. |
59 | */ |
60 | #include <sys/param.h> |
61 | #include <sys/file.h> |
62 | #ifdef _KERNEL |
63 | #include <sys/mount.h> /* to define statvfs structure */ |
64 | #include <sys/errno.h> |
65 | #include <sys/systm.h> |
66 | #include <sys/kauth.h> |
67 | #include <sys/dirent.h> |
68 | #include <sys/namei.h> |
69 | #include <sys/buf.h> |
70 | #include <sys/vnode.h> /* to define vattr structure */ |
71 | #else |
72 | #include <ffs/buf.h> |
73 | #endif |
74 | |
75 | /* |
76 | * msdosfs include files. |
77 | */ |
78 | #include <fs/msdosfs/bpb.h> |
79 | #include <fs/msdosfs/msdosfsmount.h> |
80 | #include <fs/msdosfs/direntry.h> |
81 | #include <fs/msdosfs/denode.h> |
82 | #include <fs/msdosfs/fat.h> |
83 | |
84 | /* |
85 | * Fat cache stats. |
86 | */ |
87 | int fc_fileextends; /* # of file extends */ |
88 | int fc_lfcempty; /* # of time last file cluster cache entry |
89 | * was empty */ |
90 | int fc_bmapcalls; /* # of times pcbmap was called */ |
91 | |
92 | #define LMMAX 20 |
93 | int fc_lmdistance[LMMAX]; /* counters for how far off the last |
94 | * cluster mapped entry was. */ |
95 | int fc_largedistance; /* off by more than LMMAX */ |
96 | int fc_wherefrom, fc_whereto, fc_lastclust; |
97 | int pm_fatblocksize; |
98 | |
99 | #ifdef MSDOSFS_DEBUG |
100 | #define DPRINTF(a) printf a |
101 | #else |
102 | #define DPRINTF(a) |
103 | #endif |
104 | #ifdef MSDOSFS_DEBUG |
105 | void print_fat_stats(void); |
106 | |
107 | void |
108 | print_fat_stats(void) |
109 | { |
110 | int i; |
111 | |
112 | printf("fc_fileextends=%d fc_lfcempty=%d fc_bmapcalls=%d " |
113 | "fc_largedistance=%d [%d->%d=%d] fc_lastclust=%d pm_fatblocksize=%d\n" , |
114 | fc_fileextends, fc_lfcempty, fc_bmapcalls, fc_largedistance, |
115 | fc_wherefrom, fc_whereto, fc_whereto-fc_wherefrom, |
116 | fc_lastclust, pm_fatblocksize); |
117 | |
118 | fc_fileextends = fc_lfcempty = fc_bmapcalls = 0; |
119 | fc_wherefrom = fc_whereto = fc_lastclust = 0; |
120 | |
121 | for (i = 0; i < LMMAX; i++) { |
122 | printf("%d:%d " , i, fc_lmdistance[i]); |
123 | fc_lmdistance[i] = 0; |
124 | } |
125 | |
126 | printf("\n" ); |
127 | } |
128 | #endif |
129 | |
130 | static void fatblock(struct msdosfsmount *, u_long, u_long *, u_long *, |
131 | u_long *); |
132 | void updatefats(struct msdosfsmount *, struct buf *, u_long); |
133 | static inline void usemap_free(struct msdosfsmount *, u_long); |
134 | static inline void usemap_alloc(struct msdosfsmount *, u_long); |
135 | static int fatchain(struct msdosfsmount *, u_long, u_long, u_long); |
136 | int chainlength(struct msdosfsmount *, u_long, u_long); |
137 | int chainalloc(struct msdosfsmount *, u_long, u_long, u_long, u_long *, |
138 | u_long *); |
139 | |
140 | static void |
141 | fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep, u_long *bop) |
142 | { |
143 | u_long bn, size; |
144 | |
145 | bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; |
146 | size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) |
147 | * pmp->pm_BytesPerSec; |
148 | bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; |
149 | |
150 | DPRINTF(("%s(ofs=%lu bn=%lu, size=%lu, bo=%lu)\n" , __func__, ofs, bn, |
151 | size, ofs % pmp->pm_fatblocksize)); |
152 | if (bnp) |
153 | *bnp = bn; |
154 | if (sizep) |
155 | *sizep = size; |
156 | if (bop) |
157 | *bop = ofs % pmp->pm_fatblocksize; |
158 | |
159 | pm_fatblocksize = pmp->pm_fatblocksize; |
160 | } |
161 | |
162 | /* |
163 | * Map the logical cluster number of a file into a physical disk sector |
164 | * that is filesystem relative. |
165 | * |
166 | * dep - address of denode representing the file of interest |
167 | * findcn - file relative cluster whose filesystem relative cluster number |
168 | * and/or block number are/is to be found |
169 | * bnp - address of where to place the file system relative block number. |
170 | * If this pointer is null then don't return this quantity. |
171 | * cnp - address of where to place the file system relative cluster number. |
172 | * If this pointer is null then don't return this quantity. |
173 | * |
174 | * NOTE: Either bnp or cnp must be non-null. |
175 | * This function has one side effect. If the requested file relative cluster |
176 | * is beyond the end of file, then the actual number of clusters in the file |
177 | * is returned in *cnp. This is useful for determining how long a directory is. |
178 | * If cnp is null, nothing is returned. |
179 | */ |
180 | int |
181 | pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp) |
182 | /* findcn: file relative cluster to get */ |
183 | /* bnp: returned filesys rel sector number */ |
184 | /* cnp: returned cluster number */ |
185 | /* sp: returned block size */ |
186 | { |
187 | int error; |
188 | u_long i; |
189 | u_long cn; |
190 | u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ |
191 | u_long byteoffset; |
192 | u_long bn; |
193 | u_long bo; |
194 | struct buf *bp = NULL; |
195 | u_long bp_bn = -1; |
196 | struct msdosfsmount *pmp = dep->de_pmp; |
197 | u_long bsize; |
198 | |
199 | fc_bmapcalls++; |
200 | |
201 | /* |
202 | * If they don't give us someplace to return a value then don't |
203 | * bother doing anything. |
204 | */ |
205 | if (bnp == NULL && cnp == NULL && sp == NULL) |
206 | return (0); |
207 | |
208 | cn = dep->de_StartCluster; |
209 | DPRINTF(("%s(start cluster=%lu)\n" , __func__, cn)); |
210 | /* |
211 | * The "file" that makes up the root directory is contiguous, |
212 | * permanently allocated, of fixed size, and is not made up of |
213 | * clusters. If the cluster number is beyond the end of the root |
214 | * directory, then return the number of clusters in the file. |
215 | */ |
216 | if (cn == MSDOSFSROOT) { |
217 | if (dep->de_Attributes & ATTR_DIRECTORY) { |
218 | if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { |
219 | if (cnp) |
220 | *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); |
221 | DPRINTF(("%s(root, %lu ETOOBIG)\n" , __func__, |
222 | de_cn2off(pmp, findcn))); |
223 | return (E2BIG); |
224 | } |
225 | if (bnp) |
226 | *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); |
227 | if (cnp) |
228 | *cnp = MSDOSFSROOT; |
229 | if (sp) |
230 | *sp = min(pmp->pm_bpcluster, |
231 | dep->de_FileSize - de_cn2off(pmp, findcn)); |
232 | DPRINTF(("%s(root, bn=%lu, cn=%u)\n" , __func__, |
233 | pmp->pm_rootdirblk + de_cn2bn(pmp, findcn), |
234 | MSDOSFSROOT)); |
235 | return (0); |
236 | } else { /* just an empty file */ |
237 | if (cnp) |
238 | *cnp = 0; |
239 | DPRINTF(("%s(root, empty ETOOBIG)\n" , __func__)); |
240 | return (E2BIG); |
241 | } |
242 | } |
243 | |
244 | /* |
245 | * All other files do I/O in cluster sized blocks |
246 | */ |
247 | if (sp) |
248 | *sp = pmp->pm_bpcluster; |
249 | |
250 | /* |
251 | * Rummage around in the FAT cache, maybe we can avoid tromping |
252 | * thru every FAT entry for the file. And, keep track of how far |
253 | * off the cache was from where we wanted to be. |
254 | */ |
255 | i = 0; |
256 | fc_lookup(dep, findcn, &i, &cn); |
257 | DPRINTF(("%s(bpcluster=%lu i=%lu cn=%lu\n" , __func__, pmp->pm_bpcluster, |
258 | i, cn)); |
259 | if ((bn = findcn - i) >= LMMAX) { |
260 | fc_largedistance++; |
261 | fc_wherefrom = i; |
262 | fc_whereto = findcn; |
263 | fc_lastclust = dep->de_fc[FC_LASTFC].fc_frcn; |
264 | } else |
265 | fc_lmdistance[bn]++; |
266 | |
267 | /* |
268 | * Handle all other files or directories the normal way. |
269 | */ |
270 | for (; i < findcn; i++) { |
271 | /* |
272 | * Stop with all reserved clusters, not just with EOF. |
273 | */ |
274 | if (cn >= (CLUST_RSRVD & pmp->pm_fatmask)) |
275 | goto hiteof; |
276 | |
277 | /* |
278 | * Also stop when cluster is not in the filesystem |
279 | */ |
280 | if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) { |
281 | DPRINTF(("%s(cn, %lu not in %lu..%lu)\n" , __func__, |
282 | cn, (u_long)CLUST_FIRST, pmp->pm_maxcluster)); |
283 | if (bp) |
284 | brelse(bp, 0); |
285 | return (EINVAL); |
286 | } |
287 | |
288 | byteoffset = FATOFS(pmp, cn); |
289 | fatblock(pmp, byteoffset, &bn, &bsize, &bo); |
290 | if (bn != bp_bn) { |
291 | if (bp) |
292 | brelse(bp, 0); |
293 | error = bread(pmp->pm_devvp, de_bn2kb(pmp, bn), bsize, |
294 | 0, &bp); |
295 | if (error) { |
296 | DPRINTF(("%s(bread, %d)\n" , __func__, error)); |
297 | return (error); |
298 | } |
299 | bp_bn = bn; |
300 | } |
301 | prevcn = cn; |
302 | if (bo >= bsize) { |
303 | if (bp) |
304 | brelse(bp, 0); |
305 | DPRINTF(("%s(block, %lu >= %lu)\n" , __func__, bo, |
306 | bsize)); |
307 | return (EIO); |
308 | } |
309 | KASSERT(bp != NULL); |
310 | if (FAT32(pmp)) |
311 | cn = getulong((char *)bp->b_data + bo); |
312 | else |
313 | cn = getushort((char *)bp->b_data + bo); |
314 | if (FAT12(pmp) && (prevcn & 1)) |
315 | cn >>= 4; |
316 | DPRINTF(("%s(cn=%lu masked=%lu)\n" , __func__, cn, |
317 | cn & pmp->pm_fatmask)); |
318 | cn &= pmp->pm_fatmask; |
319 | } |
320 | |
321 | if (!MSDOSFSEOF(cn, pmp->pm_fatmask)) { |
322 | if (bp) |
323 | brelse(bp, 0); |
324 | if (bnp) |
325 | *bnp = cntobn(pmp, cn); |
326 | if (cnp) |
327 | *cnp = cn; |
328 | DPRINTF(("%s(bn=%lu, cn=%lu)\n" , __func__, cntobn(pmp, cn), |
329 | cn)); |
330 | fc_setcache(dep, FC_LASTMAP, i, cn); |
331 | return (0); |
332 | } |
333 | |
334 | hiteof:; |
335 | if (cnp) |
336 | *cnp = i; |
337 | if (bp) |
338 | brelse(bp, 0); |
339 | /* update last file cluster entry in the FAT cache */ |
340 | fc_setcache(dep, FC_LASTFC, i - 1, prevcn); |
341 | DPRINTF(("%s(eof, %lu)\n" , __func__, i)); |
342 | return (E2BIG); |
343 | } |
344 | |
345 | /* |
346 | * Find the closest entry in the FAT cache to the cluster we are looking |
347 | * for. |
348 | */ |
349 | void |
350 | fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp) |
351 | { |
352 | int i; |
353 | u_long cn; |
354 | struct fatcache *closest = 0; |
355 | |
356 | for (i = 0; i < FC_SIZE; i++) { |
357 | cn = dep->de_fc[i].fc_frcn; |
358 | if (cn != FCE_EMPTY && cn <= findcn) { |
359 | if (closest == 0 || cn > closest->fc_frcn) |
360 | closest = &dep->de_fc[i]; |
361 | } |
362 | } |
363 | if (closest) { |
364 | *frcnp = closest->fc_frcn; |
365 | *fsrcnp = closest->fc_fsrcn; |
366 | } |
367 | } |
368 | |
369 | /* |
370 | * Purge the FAT cache in denode dep of all entries relating to file |
371 | * relative cluster frcn and beyond. |
372 | */ |
373 | void |
374 | fc_purge(struct denode *dep, u_int frcn) |
375 | { |
376 | int i; |
377 | struct fatcache *fcp; |
378 | |
379 | fcp = dep->de_fc; |
380 | for (i = 0; i < FC_SIZE; i++, fcp++) { |
381 | if (fcp->fc_frcn >= frcn) |
382 | fcp->fc_frcn = FCE_EMPTY; |
383 | } |
384 | } |
385 | |
386 | /* |
387 | * Update the FAT. |
388 | * If mirroring the FAT, update all copies, with the first copy as last. |
389 | * Else update only the current FAT (ignoring the others). |
390 | * |
391 | * pmp - msdosfsmount structure for filesystem to update |
392 | * bp - addr of modified FAT block |
393 | * fatbn - block number relative to begin of filesystem of the modified FAT block. |
394 | */ |
395 | void |
396 | updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn) |
397 | { |
398 | int i, error; |
399 | struct buf *bpn; |
400 | |
401 | DPRINTF(("%s(pmp %p, bp %p, fatbn %lu)\n" , __func__, pmp, bp, fatbn)); |
402 | |
403 | /* |
404 | * If we have an FSInfo block, update it. |
405 | */ |
406 | if (pmp->pm_fsinfo) { |
407 | u_long cn = pmp->pm_nxtfree; |
408 | |
409 | if (pmp->pm_freeclustercount |
410 | && (pmp->pm_inusemap[cn / N_INUSEBITS] |
411 | & (1 << (cn % N_INUSEBITS)))) { |
412 | /* |
413 | * The cluster indicated in FSInfo isn't free |
414 | * any longer. Got get a new free one. |
415 | */ |
416 | for (cn = 0; cn < pmp->pm_maxcluster; cn++) |
417 | if (pmp->pm_inusemap[cn / N_INUSEBITS] != (u_int)-1) |
418 | break; |
419 | pmp->pm_nxtfree = cn |
420 | + ffs(pmp->pm_inusemap[cn / N_INUSEBITS] |
421 | ^ (u_int)-1) - 1; |
422 | } |
423 | /* |
424 | * XXX If the fsinfo block is stored on media with |
425 | * 2KB or larger sectors, is the fsinfo structure |
426 | * padded at the end or in the middle? |
427 | */ |
428 | if (bread(pmp->pm_devvp, de_bn2kb(pmp, pmp->pm_fsinfo), |
429 | pmp->pm_BytesPerSec, B_MODIFY, &bpn) != 0) { |
430 | /* |
431 | * Ignore the error, but turn off FSInfo update for the future. |
432 | */ |
433 | pmp->pm_fsinfo = 0; |
434 | } else { |
435 | struct fsinfo *fp = (struct fsinfo *)bpn->b_data; |
436 | |
437 | putulong(fp->fsinfree, pmp->pm_freeclustercount); |
438 | putulong(fp->fsinxtfree, pmp->pm_nxtfree); |
439 | if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) |
440 | bwrite(bpn); |
441 | else |
442 | bdwrite(bpn); |
443 | } |
444 | } |
445 | |
446 | if (pmp->pm_flags & MSDOSFS_FATMIRROR) { |
447 | /* |
448 | * Now copy the block(s) of the modified FAT to the other copies of |
449 | * the FAT and write them out. This is faster than reading in the |
450 | * other FATs and then writing them back out. This could tie up |
451 | * the FAT for quite a while. Preventing others from accessing it. |
452 | * To prevent us from going after the FAT quite so much we use |
453 | * delayed writes, unless they specified "synchronous" when the |
454 | * filesystem was mounted. If synch is asked for then use |
455 | * bwrite()'s and really slow things down. |
456 | */ |
457 | for (i = 1; i < pmp->pm_FATs; i++) { |
458 | fatbn += pmp->pm_FATsecs; |
459 | /* getblk() never fails */ |
460 | bpn = getblk(pmp->pm_devvp, de_bn2kb(pmp, fatbn), |
461 | bp->b_bcount, 0, 0); |
462 | memcpy(bpn->b_data, bp->b_data, bp->b_bcount); |
463 | if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) { |
464 | error = bwrite(bpn); |
465 | if (error) |
466 | printf("%s: copy FAT %d (error=%d)\n" , |
467 | __func__, i, error); |
468 | } else |
469 | bdwrite(bpn); |
470 | } |
471 | } |
472 | |
473 | /* |
474 | * Write out the first (or current) FAT last. |
475 | */ |
476 | if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) { |
477 | error = bwrite(bp); |
478 | if (error) |
479 | printf("%s: write FAT (error=%d)\n" , |
480 | __func__, error); |
481 | } else |
482 | bdwrite(bp); |
483 | /* |
484 | * Maybe update fsinfo sector here? |
485 | */ |
486 | } |
487 | |
488 | /* |
489 | * Updating entries in 12 bit FATs is a pain in the butt. |
490 | * |
491 | * The following picture shows where nibbles go when moving from a 12 bit |
492 | * cluster number into the appropriate bytes in the FAT. |
493 | * |
494 | * byte m byte m+1 byte m+2 |
495 | * +----+----+ +----+----+ +----+----+ |
496 | * | 0 1 | | 2 3 | | 4 5 | FAT bytes |
497 | * +----+----+ +----+----+ +----+----+ |
498 | * |
499 | * +----+----+----+ +----+----+----+ |
500 | * | 3 0 1 | | 4 5 2 | |
501 | * +----+----+----+ +----+----+----+ |
502 | * cluster n cluster n+1 |
503 | * |
504 | * Where n is even. m = n + (n >> 2) |
505 | * |
506 | */ |
507 | static inline void |
508 | usemap_alloc(struct msdosfsmount *pmp, u_long cn) |
509 | { |
510 | |
511 | pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); |
512 | pmp->pm_freeclustercount--; |
513 | } |
514 | |
515 | static inline void |
516 | usemap_free(struct msdosfsmount *pmp, u_long cn) |
517 | { |
518 | |
519 | pmp->pm_freeclustercount++; |
520 | pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); |
521 | } |
522 | |
523 | int |
524 | clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp) |
525 | { |
526 | int error; |
527 | u_long oldcn; |
528 | |
529 | usemap_free(pmp, cluster); |
530 | error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); |
531 | if (error) { |
532 | usemap_alloc(pmp, cluster); |
533 | return (error); |
534 | } |
535 | /* |
536 | * If the cluster was successfully marked free, then update |
537 | * the count of free clusters, and turn off the "allocated" |
538 | * bit in the "in use" cluster bit map. |
539 | */ |
540 | if (oldcnp) |
541 | *oldcnp = oldcn; |
542 | return (0); |
543 | } |
544 | |
545 | /* |
546 | * Get or Set or 'Get and Set' the cluster'th entry in the FAT. |
547 | * |
548 | * function - whether to get or set a fat entry |
549 | * pmp - address of the msdosfsmount structure for the filesystem |
550 | * whose FAT is to be manipulated. |
551 | * cn - which cluster is of interest |
552 | * oldcontents - address of a word that is to receive the contents of the |
553 | * cluster'th entry if this is a get function |
554 | * newcontents - the new value to be written into the cluster'th element of |
555 | * the FAT if this is a set function. |
556 | * |
557 | * This function can also be used to free a cluster by setting the FAT entry |
558 | * for a cluster to 0. |
559 | * |
560 | * All copies of the FAT are updated if this is a set function. NOTE: If |
561 | * fatentry() marks a cluster as free it does not update the inusemap in |
562 | * the msdosfsmount structure. This is left to the caller. |
563 | */ |
564 | int |
565 | fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, u_long newcontents) |
566 | { |
567 | int error; |
568 | u_long readcn; |
569 | u_long bn, bo, bsize, byteoffset; |
570 | struct buf *bp; |
571 | |
572 | DPRINTF(("%s(func %d, pmp %p, clust %lu, oldcon %p, newcon " "%lx)\n" , |
573 | __func__, function, pmp, cn, oldcontents, newcontents)); |
574 | |
575 | #ifdef DIAGNOSTIC |
576 | /* |
577 | * Be sure they asked us to do something. |
578 | */ |
579 | if ((function & (FAT_SET | FAT_GET)) == 0) { |
580 | DPRINTF(("%s(): function code doesn't specify get or set\n" , |
581 | __func__)); |
582 | return (EINVAL); |
583 | } |
584 | |
585 | /* |
586 | * If they asked us to return a cluster number but didn't tell us |
587 | * where to put it, give them an error. |
588 | */ |
589 | if ((function & FAT_GET) && oldcontents == NULL) { |
590 | DPRINTF(("%s(): get function with no place to put result\n" , |
591 | __func__)); |
592 | return (EINVAL); |
593 | } |
594 | #endif |
595 | |
596 | /* |
597 | * Be sure the requested cluster is in the filesystem. |
598 | */ |
599 | if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) |
600 | return (EINVAL); |
601 | |
602 | byteoffset = FATOFS(pmp, cn); |
603 | fatblock(pmp, byteoffset, &bn, &bsize, &bo); |
604 | if ((error = bread(pmp->pm_devvp, de_bn2kb(pmp, bn), bsize, |
605 | 0, &bp)) != 0) { |
606 | return (error); |
607 | } |
608 | |
609 | if (function & FAT_GET) { |
610 | if (FAT32(pmp)) |
611 | readcn = getulong((char *)bp->b_data + bo); |
612 | else |
613 | readcn = getushort((char *)bp->b_data + bo); |
614 | if (FAT12(pmp) & (cn & 1)) |
615 | readcn >>= 4; |
616 | readcn &= pmp->pm_fatmask; |
617 | *oldcontents = readcn; |
618 | } |
619 | if (function & FAT_SET) { |
620 | switch (pmp->pm_fatmask) { |
621 | case FAT12_MASK: |
622 | readcn = getushort((char *)bp->b_data + bo); |
623 | if (cn & 1) { |
624 | readcn &= 0x000f; |
625 | readcn |= newcontents << 4; |
626 | } else { |
627 | readcn &= 0xf000; |
628 | readcn |= newcontents & 0xfff; |
629 | } |
630 | putushort((char *)bp->b_data + bo, readcn); |
631 | break; |
632 | case FAT16_MASK: |
633 | putushort((char *)bp->b_data + bo, newcontents); |
634 | break; |
635 | case FAT32_MASK: |
636 | /* |
637 | * According to spec we have to retain the |
638 | * high order bits of the FAT entry. |
639 | */ |
640 | readcn = getulong((char *)bp->b_data + bo); |
641 | readcn &= ~FAT32_MASK; |
642 | readcn |= newcontents & FAT32_MASK; |
643 | putulong((char *)bp->b_data + bo, readcn); |
644 | break; |
645 | } |
646 | updatefats(pmp, bp, bn); |
647 | bp = NULL; |
648 | pmp->pm_fmod = 1; |
649 | } |
650 | if (bp) |
651 | brelse(bp, 0); |
652 | return (0); |
653 | } |
654 | |
655 | /* |
656 | * Update a contiguous cluster chain |
657 | * |
658 | * pmp - mount point |
659 | * start - first cluster of chain |
660 | * count - number of clusters in chain |
661 | * fillwith - what to write into FAT entry of last cluster |
662 | */ |
663 | static int |
664 | fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) |
665 | { |
666 | int error; |
667 | u_long bn, bo, bsize, byteoffset, readcn, newc; |
668 | struct buf *bp; |
669 | |
670 | DPRINTF(("%s(pmp %p, start %lu, count %lu, fillwith %lx)\n" , __func__, |
671 | pmp, start, count, fillwith)); |
672 | /* |
673 | * Be sure the clusters are in the filesystem. |
674 | */ |
675 | if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) |
676 | return (EINVAL); |
677 | |
678 | while (count > 0) { |
679 | byteoffset = FATOFS(pmp, start); |
680 | fatblock(pmp, byteoffset, &bn, &bsize, &bo); |
681 | error = bread(pmp->pm_devvp, de_bn2kb(pmp, bn), bsize, |
682 | B_MODIFY, &bp); |
683 | if (error) { |
684 | return (error); |
685 | } |
686 | while (count > 0) { |
687 | start++; |
688 | newc = --count > 0 ? start : fillwith; |
689 | switch (pmp->pm_fatmask) { |
690 | case FAT12_MASK: |
691 | readcn = getushort((char *)bp->b_data + bo); |
692 | if (start & 1) { |
693 | readcn &= 0xf000; |
694 | readcn |= newc & 0xfff; |
695 | } else { |
696 | readcn &= 0x000f; |
697 | readcn |= newc << 4; |
698 | } |
699 | putushort((char *)bp->b_data + bo, readcn); |
700 | bo++; |
701 | if (!(start & 1)) |
702 | bo++; |
703 | break; |
704 | case FAT16_MASK: |
705 | putushort((char *)bp->b_data + bo, newc); |
706 | bo += 2; |
707 | break; |
708 | case FAT32_MASK: |
709 | readcn = getulong((char *)bp->b_data + bo); |
710 | readcn &= ~pmp->pm_fatmask; |
711 | readcn |= newc & pmp->pm_fatmask; |
712 | putulong((char *)bp->b_data + bo, readcn); |
713 | bo += 4; |
714 | break; |
715 | } |
716 | if (bo >= bsize) |
717 | break; |
718 | } |
719 | updatefats(pmp, bp, bn); |
720 | } |
721 | pmp->pm_fmod = 1; |
722 | return (0); |
723 | } |
724 | |
725 | /* |
726 | * Check the length of a free cluster chain starting at start. |
727 | * |
728 | * pmp - mount point |
729 | * start - start of chain |
730 | * count - maximum interesting length |
731 | */ |
732 | int |
733 | chainlength(struct msdosfsmount *pmp, u_long start, u_long count) |
734 | { |
735 | u_long idx, max_idx; |
736 | u_int map; |
737 | u_long len; |
738 | |
739 | max_idx = pmp->pm_maxcluster / N_INUSEBITS; |
740 | idx = start / N_INUSEBITS; |
741 | start %= N_INUSEBITS; |
742 | map = pmp->pm_inusemap[idx]; |
743 | map &= ~((1 << start) - 1); |
744 | if (map) { |
745 | len = ffs(map) - 1 - start; |
746 | return (len > count ? count : len); |
747 | } |
748 | len = N_INUSEBITS - start; |
749 | if (len >= count) |
750 | return (count); |
751 | while (++idx <= max_idx) { |
752 | if (len >= count) |
753 | break; |
754 | if ((map = pmp->pm_inusemap[idx]) != 0) { |
755 | len += ffs(map) - 1; |
756 | break; |
757 | } |
758 | len += N_INUSEBITS; |
759 | } |
760 | return (len > count ? count : len); |
761 | } |
762 | |
763 | /* |
764 | * Allocate contigous free clusters. |
765 | * |
766 | * pmp - mount point. |
767 | * start - start of cluster chain. |
768 | * count - number of clusters to allocate. |
769 | * fillwith - put this value into the FAT entry for the |
770 | * last allocated cluster. |
771 | * retcluster - put the first allocated cluster's number here. |
772 | * got - how many clusters were actually allocated. |
773 | */ |
774 | int |
775 | chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith, u_long *retcluster, u_long *got) |
776 | { |
777 | int error; |
778 | u_long cl, n; |
779 | |
780 | for (cl = start, n = count; n-- > 0;) |
781 | usemap_alloc(pmp, cl++); |
782 | if ((error = fatchain(pmp, start, count, fillwith)) != 0) |
783 | return (error); |
784 | |
785 | DPRINTF(("%s(): allocated cluster chain at %lu (%lu clusters)\n" , |
786 | __func__, start, count)); |
787 | if (retcluster) |
788 | *retcluster = start; |
789 | if (got) |
790 | *got = count; |
791 | return (0); |
792 | } |
793 | |
794 | /* |
795 | * Allocate contiguous free clusters. |
796 | * |
797 | * pmp - mount point. |
798 | * start - preferred start of cluster chain. |
799 | * count - number of clusters requested. |
800 | * fillwith - put this value into the FAT entry for the |
801 | * last allocated cluster. |
802 | * retcluster - put the first allocated cluster's number here. |
803 | * got - how many clusters were actually allocated. |
804 | */ |
805 | int |
806 | clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, u_long *retcluster, u_long *got) |
807 | { |
808 | u_long idx; |
809 | u_long len, newst, foundl, cn, l; |
810 | u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ |
811 | u_long fillwith = CLUST_EOFE; |
812 | u_int map; |
813 | |
814 | DPRINTF(("%s(): find %lu clusters\n" , __func__, count)); |
815 | if (start) { |
816 | if ((len = chainlength(pmp, start, count)) >= count) |
817 | return (chainalloc(pmp, start, count, fillwith, retcluster, got)); |
818 | } else { |
819 | /* |
820 | * This is a new file, initialize start |
821 | */ |
822 | struct timeval tv; |
823 | |
824 | microtime(&tv); |
825 | start = (tv.tv_usec >> 10) | tv.tv_usec; |
826 | len = 0; |
827 | } |
828 | |
829 | /* |
830 | * Start at a (pseudo) random place to maximize cluster runs |
831 | * under multiple writers. |
832 | */ |
833 | newst = (start * 1103515245 + 12345) % (pmp->pm_maxcluster + 1); |
834 | foundl = 0; |
835 | |
836 | for (cn = newst; cn <= pmp->pm_maxcluster;) { |
837 | idx = cn / N_INUSEBITS; |
838 | map = pmp->pm_inusemap[idx]; |
839 | map |= (1 << (cn % N_INUSEBITS)) - 1; |
840 | if (map != (u_int)-1) { |
841 | cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; |
842 | if ((l = chainlength(pmp, cn, count)) >= count) |
843 | return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); |
844 | if (l > foundl) { |
845 | foundcn = cn; |
846 | foundl = l; |
847 | } |
848 | cn += l + 1; |
849 | continue; |
850 | } |
851 | cn += N_INUSEBITS - cn % N_INUSEBITS; |
852 | } |
853 | for (cn = 0; cn < newst;) { |
854 | idx = cn / N_INUSEBITS; |
855 | map = pmp->pm_inusemap[idx]; |
856 | map |= (1 << (cn % N_INUSEBITS)) - 1; |
857 | if (map != (u_int)-1) { |
858 | cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; |
859 | if ((l = chainlength(pmp, cn, count)) >= count) |
860 | return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); |
861 | if (l > foundl) { |
862 | foundcn = cn; |
863 | foundl = l; |
864 | } |
865 | cn += l + 1; |
866 | continue; |
867 | } |
868 | cn += N_INUSEBITS - cn % N_INUSEBITS; |
869 | } |
870 | |
871 | if (!foundl) |
872 | return (ENOSPC); |
873 | |
874 | if (len) |
875 | return (chainalloc(pmp, start, len, fillwith, retcluster, got)); |
876 | else |
877 | return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); |
878 | } |
879 | |
880 | |
881 | /* |
882 | * Free a chain of clusters. |
883 | * |
884 | * pmp - address of the msdosfs mount structure for the filesystem |
885 | * containing the cluster chain to be freed. |
886 | * startcluster - number of the 1st cluster in the chain of clusters to be |
887 | * freed. |
888 | */ |
889 | int |
890 | freeclusterchain(struct msdosfsmount *pmp, u_long cluster) |
891 | { |
892 | int error; |
893 | struct buf *bp = NULL; |
894 | u_long bn, bo, bsize, byteoffset; |
895 | u_long readcn, lbn = -1; |
896 | |
897 | while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { |
898 | byteoffset = FATOFS(pmp, cluster); |
899 | fatblock(pmp, byteoffset, &bn, &bsize, &bo); |
900 | if (lbn != bn) { |
901 | if (bp) |
902 | updatefats(pmp, bp, lbn); |
903 | error = bread(pmp->pm_devvp, de_bn2kb(pmp, bn), bsize, |
904 | B_MODIFY, &bp); |
905 | if (error) { |
906 | return (error); |
907 | } |
908 | lbn = bn; |
909 | } |
910 | usemap_free(pmp, cluster); |
911 | KASSERT(bp != NULL); |
912 | switch (pmp->pm_fatmask) { |
913 | case FAT12_MASK: |
914 | readcn = getushort((char *)bp->b_data + bo); |
915 | if (cluster & 1) { |
916 | cluster = readcn >> 4; |
917 | readcn &= 0x000f; |
918 | readcn |= MSDOSFSFREE << 4; |
919 | } else { |
920 | cluster = readcn; |
921 | readcn &= 0xf000; |
922 | readcn |= MSDOSFSFREE & 0xfff; |
923 | } |
924 | putushort((char *)bp->b_data + bo, readcn); |
925 | break; |
926 | case FAT16_MASK: |
927 | cluster = getushort((char *)bp->b_data + bo); |
928 | putushort((char *)bp->b_data + bo, MSDOSFSFREE); |
929 | break; |
930 | case FAT32_MASK: |
931 | cluster = getulong((char *)bp->b_data + bo); |
932 | putulong((char *)bp->b_data + bo, |
933 | (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); |
934 | break; |
935 | } |
936 | cluster &= pmp->pm_fatmask; |
937 | } |
938 | if (bp) |
939 | updatefats(pmp, bp, bn); |
940 | return (0); |
941 | } |
942 | |
943 | /* |
944 | * Read in FAT blocks looking for free clusters. For every free cluster |
945 | * found turn off its corresponding bit in the pm_inusemap. |
946 | */ |
947 | int |
948 | fillinusemap(struct msdosfsmount *pmp) |
949 | { |
950 | struct buf *bp = NULL; |
951 | u_long cn, readcn; |
952 | int error; |
953 | u_long bn, bo, bsize, byteoffset; |
954 | |
955 | /* |
956 | * Mark all clusters in use, we mark the free ones in the FAT scan |
957 | * loop further down. |
958 | */ |
959 | for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) |
960 | pmp->pm_inusemap[cn] = (u_int)-1; |
961 | |
962 | /* |
963 | * Figure how many free clusters are in the filesystem by ripping |
964 | * through the FAT counting the number of entries whose content is |
965 | * zero. These represent free clusters. |
966 | */ |
967 | pmp->pm_freeclustercount = 0; |
968 | for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { |
969 | byteoffset = FATOFS(pmp, cn); |
970 | bo = byteoffset % pmp->pm_fatblocksize; |
971 | if (!bo || !bp) { |
972 | /* Read new FAT block */ |
973 | if (bp) |
974 | brelse(bp, 0); |
975 | fatblock(pmp, byteoffset, &bn, &bsize, NULL); |
976 | error = bread(pmp->pm_devvp, de_bn2kb(pmp, bn), bsize, |
977 | 0, &bp); |
978 | if (error) { |
979 | return (error); |
980 | } |
981 | } |
982 | if (FAT32(pmp)) |
983 | readcn = getulong((char *)bp->b_data + bo); |
984 | else |
985 | readcn = getushort((char *)bp->b_data + bo); |
986 | if (FAT12(pmp) && (cn & 1)) |
987 | readcn >>= 4; |
988 | readcn &= pmp->pm_fatmask; |
989 | |
990 | if (readcn == 0) |
991 | usemap_free(pmp, cn); |
992 | } |
993 | if (bp) |
994 | brelse(bp, 0); |
995 | return (0); |
996 | } |
997 | |
998 | /* |
999 | * Allocate a new cluster and chain it onto the end of the file. |
1000 | * |
1001 | * dep - the file to extend |
1002 | * count - number of clusters to allocate |
1003 | * bpp - where to return the address of the buf header for the first new |
1004 | * file block |
1005 | * ncp - where to put cluster number of the first newly allocated cluster |
1006 | * If this pointer is 0, do not return the cluster number. |
1007 | * flags - see fat.h |
1008 | * |
1009 | * NOTE: This function is not responsible for turning on the DE_UPDATE bit of |
1010 | * the de_flag field of the denode and it does not change the de_FileSize |
1011 | * field. This is left for the caller to do. |
1012 | */ |
1013 | |
1014 | int |
1015 | extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp, int flags) |
1016 | { |
1017 | int error; |
1018 | u_long frcn = 0, cn, got; |
1019 | struct msdosfsmount *pmp = dep->de_pmp; |
1020 | struct buf *bp; |
1021 | |
1022 | /* |
1023 | * Don't try to extend the root directory |
1024 | */ |
1025 | if (dep->de_StartCluster == MSDOSFSROOT |
1026 | && (dep->de_Attributes & ATTR_DIRECTORY)) { |
1027 | DPRINTF(("%s(): attempt to extend root directory\n" , __func__)); |
1028 | return (ENOSPC); |
1029 | } |
1030 | |
1031 | /* |
1032 | * If the "file's last cluster" cache entry is empty, and the file |
1033 | * is not empty, then fill the cache entry by calling pcbmap(). |
1034 | */ |
1035 | fc_fileextends++; |
1036 | if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && |
1037 | dep->de_StartCluster != 0) { |
1038 | fc_lfcempty++; |
1039 | error = pcbmap(dep, CLUST_END, 0, &cn, 0); |
1040 | /* we expect it to return E2BIG */ |
1041 | if (error != E2BIG) |
1042 | return (error); |
1043 | } |
1044 | |
1045 | fc_last_to_nexttolast(dep); |
1046 | |
1047 | while (count > 0) { |
1048 | |
1049 | /* |
1050 | * Allocate a new cluster chain and cat onto the end of the |
1051 | * file. If the file is empty we make de_StartCluster point |
1052 | * to the new block. Note that de_StartCluster being 0 is |
1053 | * sufficient to be sure the file is empty since we exclude |
1054 | * attempts to extend the root directory above, and the root |
1055 | * dir is the only file with a startcluster of 0 that has |
1056 | * blocks allocated (sort of). |
1057 | */ |
1058 | |
1059 | if (dep->de_StartCluster == 0) |
1060 | cn = 0; |
1061 | else |
1062 | cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; |
1063 | error = clusteralloc(pmp, cn, count, &cn, &got); |
1064 | if (error) |
1065 | return (error); |
1066 | |
1067 | count -= got; |
1068 | |
1069 | /* |
1070 | * Give them the filesystem relative cluster number if they want |
1071 | * it. |
1072 | */ |
1073 | if (ncp) { |
1074 | *ncp = cn; |
1075 | ncp = NULL; |
1076 | } |
1077 | |
1078 | if (dep->de_StartCluster == 0) { |
1079 | dep->de_StartCluster = cn; |
1080 | frcn = 0; |
1081 | } else { |
1082 | error = fatentry(FAT_SET, pmp, |
1083 | dep->de_fc[FC_LASTFC].fc_fsrcn, |
1084 | 0, cn); |
1085 | if (error) { |
1086 | clusterfree(pmp, cn, NULL); |
1087 | return (error); |
1088 | } |
1089 | frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; |
1090 | } |
1091 | |
1092 | /* |
1093 | * Update the "last cluster of the file" entry in the |
1094 | * denode's FAT cache. |
1095 | */ |
1096 | |
1097 | fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); |
1098 | if ((flags & DE_CLEAR) && |
1099 | (dep->de_Attributes & ATTR_DIRECTORY)) { |
1100 | while (got-- > 0) { |
1101 | bp = getblk(pmp->pm_devvp, |
1102 | de_bn2kb(pmp, cntobn(pmp, cn++)), |
1103 | pmp->pm_bpcluster, 0, 0); |
1104 | clrbuf(bp); |
1105 | if (bpp) { |
1106 | *bpp = bp; |
1107 | bpp = NULL; |
1108 | } else { |
1109 | bdwrite(bp); |
1110 | } |
1111 | } |
1112 | } |
1113 | } |
1114 | |
1115 | return (0); |
1116 | } |
1117 | |