Rename printf -> kprintf in sys/ and add some defines where necessary
[dragonfly.git] / sys / vfs / msdosfs / msdosfs_fat.c
CommitLineData
984263bc 1/* $FreeBSD: src/sys/msdosfs/msdosfs_fat.c,v 1.23 2000/01/27 14:43:06 nyan Exp $ */
086c1d7e 2/* $DragonFly: src/sys/vfs/msdosfs/msdosfs_fat.c,v 1.11 2006/12/23 00:41:29 swildner Exp $ */
984263bc
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3/* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 ws Exp $ */
4
5/*-
6 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
7 * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
8 * All rights reserved.
9 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 * must display the following acknowledgement:
21 * This product includes software developed by TooLs GmbH.
22 * 4. The name of TooLs GmbH may not be used to endorse or promote products
23 * derived from this software without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
28 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
29 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
30 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
31 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
32 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
33 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
34 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35 */
36/*
37 * Written by Paul Popelka (paulp@uts.amdahl.com)
38 *
39 * You can do anything you want with this software, just don't say you wrote
40 * it, and don't remove this notice.
41 *
42 * This software is provided "as is".
43 *
44 * The author supplies this software to be publicly redistributed on the
45 * understanding that the author is not responsible for the correct
46 * functioning of this software in any circumstances and is not liable for
47 * any damages caused by this software.
48 *
49 * October 1992
50 */
51
52/*
53 * kernel include files.
54 */
55#include <sys/param.h>
56#include <sys/systm.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 */
1f2de5d4
MD
64#include "bpb.h"
65#include "msdosfsmount.h"
66#include "direntry.h"
67#include "denode.h"
68#include "fat.h"
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69
70/*
71 * Fat cache stats.
72 */
73static int fc_fileextends; /* # of file extends */
74static int fc_lfcempty; /* # of time last file cluster cache entry
75 * was empty */
76static int fc_bmapcalls; /* # of times pcbmap was called */
77
78#define LMMAX 20
79static int fc_lmdistance[LMMAX];/* counters for how far off the last
80 * cluster mapped entry was. */
81static int fc_largedistance; /* off by more than LMMAX */
82
a6ee311a 83static int chainalloc (struct msdosfsmount *pmp, u_long start,
984263bc 84 u_long count, u_long fillwith,
a6ee311a
RG
85 u_long *retcluster, u_long *got);
86static int chainlength (struct msdosfsmount *pmp, u_long start,
87 u_long count);
88static void fatblock (struct msdosfsmount *pmp, u_long ofs,
89 u_long *bnp, u_long *sizep, u_long *bop);
90static int fatchain (struct msdosfsmount *pmp, u_long start,
91 u_long count, u_long fillwith);
92static void fc_lookup (struct denode *dep, u_long findcn,
93 u_long *frcnp, u_long *fsrcnp);
94static void updatefats (struct msdosfsmount *pmp, struct buf *bp,
95 u_long fatbn);
984263bc 96static __inline void
a6ee311a 97 usemap_alloc (struct msdosfsmount *pmp, u_long cn);
984263bc 98static __inline void
a6ee311a 99 usemap_free (struct msdosfsmount *pmp, u_long cn);
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100
101static void
4625f023
CP
102fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep,
103 u_long *bop)
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MD
104{
105 u_long bn, size;
106
107 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec;
108 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn)
109 * DEV_BSIZE;
110 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs;
111
112 if (bnp)
113 *bnp = bn;
114 if (sizep)
115 *sizep = size;
116 if (bop)
117 *bop = ofs % pmp->pm_fatblocksize;
118}
119
120/*
121 * Map the logical cluster number of a file into a physical disk sector
122 * that is filesystem relative.
123 *
124 * dep - address of denode representing the file of interest
125 * findcn - file relative cluster whose filesystem relative cluster number
126 * and/or block number are/is to be found
127 * bnp - address of where to place the file system relative block number.
128 * If this pointer is null then don't return this quantity.
129 * cnp - address of where to place the file system relative cluster number.
130 * If this pointer is null then don't return this quantity.
131 *
132 * NOTE: Either bnp or cnp must be non-null.
133 * This function has one side effect. If the requested file relative cluster
134 * is beyond the end of file, then the actual number of clusters in the file
135 * is returned in *cnp. This is useful for determining how long a directory is.
136 * If cnp is null, nothing is returned.
137 */
138int
4625f023
CP
139pcbmap(struct denode *dep,
140 u_long findcn, /* file relative cluster to get */
141 daddr_t *bnp, /* returned filesys relative blk number */
142 u_long *cnp, /* returned cluster number */
143 int *sp) /* returned block size */
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144{
145 int error;
146 u_long i;
147 u_long cn;
148 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */
149 u_long byteoffset;
150 u_long bn;
151 u_long bo;
152 struct buf *bp = NULL;
153 u_long bp_bn = -1;
154 struct msdosfsmount *pmp = dep->de_pmp;
155 u_long bsize;
156
157 fc_bmapcalls++;
158
159 /*
160 * If they don't give us someplace to return a value then don't
161 * bother doing anything.
162 */
163 if (bnp == NULL && cnp == NULL && sp == NULL)
164 return (0);
165
166 cn = dep->de_StartCluster;
167 /*
168 * The "file" that makes up the root directory is contiguous,
169 * permanently allocated, of fixed size, and is not made up of
170 * clusters. If the cluster number is beyond the end of the root
171 * directory, then return the number of clusters in the file.
172 */
173 if (cn == MSDOSFSROOT) {
174 if (dep->de_Attributes & ATTR_DIRECTORY) {
175 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) {
176 if (cnp)
177 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize);
178 return (E2BIG);
179 }
180 if (bnp)
181 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn);
182 if (cnp)
183 *cnp = MSDOSFSROOT;
184 if (sp)
185 *sp = min(pmp->pm_bpcluster,
186 dep->de_FileSize - de_cn2off(pmp, findcn));
187 return (0);
188 } else { /* just an empty file */
189 if (cnp)
190 *cnp = 0;
191 return (E2BIG);
192 }
193 }
194
195 /*
196 * All other files do I/O in cluster sized blocks
197 */
198 if (sp)
199 *sp = pmp->pm_bpcluster;
200
201 /*
202 * Rummage around in the fat cache, maybe we can avoid tromping
203 * thru every fat entry for the file. And, keep track of how far
204 * off the cache was from where we wanted to be.
205 */
206 i = 0;
207 fc_lookup(dep, findcn, &i, &cn);
208 if ((bn = findcn - i) >= LMMAX)
209 fc_largedistance++;
210 else
211 fc_lmdistance[bn]++;
212
213 /*
214 * Handle all other files or directories the normal way.
215 */
216 for (; i < findcn; i++) {
217 /*
218 * Stop with all reserved clusters, not just with EOF.
219 */
220 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
221 goto hiteof;
222 byteoffset = FATOFS(pmp, cn);
223 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
224 if (bn != bp_bn) {
225 if (bp)
226 brelse(bp);
54078292 227 error = bread(pmp->pm_devvp, de_bntodoff(pmp, bn), bsize, &bp);
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MD
228 if (error) {
229 brelse(bp);
230 return (error);
231 }
232 bp_bn = bn;
233 }
234 prevcn = cn;
235 if (FAT32(pmp))
236 cn = getulong(&bp->b_data[bo]);
237 else
238 cn = getushort(&bp->b_data[bo]);
239 if (FAT12(pmp) && (prevcn & 1))
240 cn >>= 4;
241 cn &= pmp->pm_fatmask;
242
243 /*
244 * Force the special cluster numbers
245 * to be the same for all cluster sizes
246 * to let the rest of msdosfs handle
247 * all cases the same.
248 */
249 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
250 cn |= ~pmp->pm_fatmask;
251 }
252
253 if (!MSDOSFSEOF(pmp, cn)) {
254 if (bp)
255 brelse(bp);
256 if (bnp)
4afd80f1 257 *bnp = xcntobn(pmp, cn);
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258 if (cnp)
259 *cnp = cn;
260 fc_setcache(dep, FC_LASTMAP, i, cn);
261 return (0);
262 }
263
264hiteof:;
265 if (cnp)
266 *cnp = i;
267 if (bp)
268 brelse(bp);
269 /* update last file cluster entry in the fat cache */
270 fc_setcache(dep, FC_LASTFC, i - 1, prevcn);
271 return (E2BIG);
272}
273
274/*
275 * Find the closest entry in the fat cache to the cluster we are looking
276 * for.
277 */
278static void
4625f023 279fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp)
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MD
280{
281 int i;
282 u_long cn;
283 struct fatcache *closest = 0;
284
285 for (i = 0; i < FC_SIZE; i++) {
286 cn = dep->de_fc[i].fc_frcn;
287 if (cn != FCE_EMPTY && cn <= findcn) {
288 if (closest == 0 || cn > closest->fc_frcn)
289 closest = &dep->de_fc[i];
290 }
291 }
292 if (closest) {
293 *frcnp = closest->fc_frcn;
294 *fsrcnp = closest->fc_fsrcn;
295 }
296}
297
298/*
299 * Purge the fat cache in denode dep of all entries relating to file
300 * relative cluster frcn and beyond.
301 */
302void
4625f023 303fc_purge(struct denode *dep, u_int frcn)
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MD
304{
305 int i;
306 struct fatcache *fcp;
307
308 fcp = dep->de_fc;
309 for (i = 0; i < FC_SIZE; i++, fcp++) {
310 if (fcp->fc_frcn >= frcn)
311 fcp->fc_frcn = FCE_EMPTY;
312 }
313}
314
315/*
316 * Update the fat.
317 * If mirroring the fat, update all copies, with the first copy as last.
318 * Else update only the current fat (ignoring the others).
319 *
320 * pmp - msdosfsmount structure for filesystem to update
321 * bp - addr of modified fat block
322 * fatbn - block number relative to begin of filesystem of the modified fat block.
323 */
324static void
4625f023 325updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn)
984263bc
MD
326{
327 int i;
328 struct buf *bpn;
329
330#ifdef MSDOSFS_DEBUG
086c1d7e 331 kprintf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn);
984263bc
MD
332#endif
333
334 /*
335 * If we have an FSInfo block, update it.
336 */
337 if (pmp->pm_fsinfo) {
338 u_long cn = pmp->pm_nxtfree;
339
340 if (pmp->pm_freeclustercount
341 && (pmp->pm_inusemap[cn / N_INUSEBITS]
342 & (1 << (cn % N_INUSEBITS)))) {
343 /*
344 * The cluster indicated in FSInfo isn't free
345 * any longer. Got get a new free one.
346 */
347 for (cn = 0; cn < pmp->pm_maxcluster; cn += N_INUSEBITS)
348 if (pmp->pm_inusemap[cn / N_INUSEBITS] != (u_int)-1)
349 break;
350 pmp->pm_nxtfree = cn
351 + ffs(pmp->pm_inusemap[cn / N_INUSEBITS]
352 ^ (u_int)-1) - 1;
353 }
54078292 354 if (bread(pmp->pm_devvp, de_bntodoff(pmp, pmp->pm_fsinfo), fsi_size(pmp), &bpn) != 0) {
984263bc
MD
355 /*
356 * Ignore the error, but turn off FSInfo update for the future.
357 */
358 pmp->pm_fsinfo = 0;
359 brelse(bpn);
360 } else {
361 struct fsinfo *fp = (struct fsinfo *)bpn->b_data;
362
363 putulong(fp->fsinfree, pmp->pm_freeclustercount);
364 putulong(fp->fsinxtfree, pmp->pm_nxtfree);
365 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT)
366 bwrite(bpn);
367 else
368 bdwrite(bpn);
369 }
370 }
371
372 if (pmp->pm_flags & MSDOSFS_FATMIRROR) {
373 /*
374 * Now copy the block(s) of the modified fat to the other copies of
375 * the fat and write them out. This is faster than reading in the
376 * other fats and then writing them back out. This could tie up
377 * the fat for quite a while. Preventing others from accessing it.
378 * To prevent us from going after the fat quite so much we use
379 * delayed writes, unless they specfied "synchronous" when the
380 * filesystem was mounted. If synch is asked for then use
381 * bwrite()'s and really slow things down.
382 */
383 for (i = 1; i < pmp->pm_FATs; i++) {
384 fatbn += pmp->pm_FATsecs;
385 /* getblk() never fails */
54078292
MD
386 bpn = getblk(pmp->pm_devvp, de_bntodoff(pmp, fatbn),
387 bp->b_bcount, 0, 0);
984263bc
MD
388 bcopy(bp->b_data, bpn->b_data, bp->b_bcount);
389 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT)
390 bwrite(bpn);
391 else
392 bdwrite(bpn);
393 }
394 }
395
396 /*
397 * Write out the first (or current) fat last.
398 */
399 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT)
400 bwrite(bp);
401 else
402 bdwrite(bp);
403 /*
404 * Maybe update fsinfo sector here?
405 */
406}
407
408/*
409 * Updating entries in 12 bit fats is a pain in the butt.
410 *
411 * The following picture shows where nibbles go when moving from a 12 bit
412 * cluster number into the appropriate bytes in the FAT.
413 *
414 * byte m byte m+1 byte m+2
415 * +----+----+ +----+----+ +----+----+
416 * | 0 1 | | 2 3 | | 4 5 | FAT bytes
417 * +----+----+ +----+----+ +----+----+
418 *
419 * +----+----+----+ +----+----+----+
420 * | 3 0 1 | | 4 5 2 |
421 * +----+----+----+ +----+----+----+
422 * cluster n cluster n+1
423 *
424 * Where n is even. m = n + (n >> 2)
425 *
426 */
427static __inline void
4625f023 428usemap_alloc(struct msdosfsmount *pmp, u_long cn)
984263bc
MD
429{
430
431 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS);
432 pmp->pm_freeclustercount--;
433}
434
435static __inline void
4625f023 436usemap_free(struct msdosfsmount *pmp, u_long cn)
984263bc
MD
437{
438
439 pmp->pm_freeclustercount++;
440 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS));
441}
442
443int
4625f023 444clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp)
984263bc
MD
445{
446 int error;
447 u_long oldcn;
448
449 usemap_free(pmp, cluster);
450 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE);
451 if (error) {
452 usemap_alloc(pmp, cluster);
453 return (error);
454 }
455 /*
456 * If the cluster was successfully marked free, then update
457 * the count of free clusters, and turn off the "allocated"
458 * bit in the "in use" cluster bit map.
459 */
460 if (oldcnp)
461 *oldcnp = oldcn;
462 return (0);
463}
464
465/*
466 * Get or Set or 'Get and Set' the cluster'th entry in the fat.
467 *
468 * function - whether to get or set a fat entry
469 * pmp - address of the msdosfsmount structure for the filesystem
470 * whose fat is to be manipulated.
471 * cn - which cluster is of interest
472 * oldcontents - address of a word that is to receive the contents of the
473 * cluster'th entry if this is a get function
474 * newcontents - the new value to be written into the cluster'th element of
475 * the fat if this is a set function.
476 *
477 * This function can also be used to free a cluster by setting the fat entry
478 * for a cluster to 0.
479 *
480 * All copies of the fat are updated if this is a set function. NOTE: If
481 * fatentry() marks a cluster as free it does not update the inusemap in
482 * the msdosfsmount structure. This is left to the caller.
483 */
484int
4625f023
CP
485fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents,
486 u_long newcontents)
984263bc
MD
487{
488 int error;
489 u_long readcn;
490 u_long bn, bo, bsize, byteoffset;
491 struct buf *bp;
492
493#ifdef MSDOSFS_DEBUG
086c1d7e 494 kprintf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n",
984263bc
MD
495 function, pmp, cn, oldcontents, newcontents);
496#endif
497
498#ifdef DIAGNOSTIC
499 /*
500 * Be sure they asked us to do something.
501 */
502 if ((function & (FAT_SET | FAT_GET)) == 0) {
086c1d7e 503 kprintf("fatentry(): function code doesn't specify get or set\n");
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MD
504 return (EINVAL);
505 }
506
507 /*
508 * If they asked us to return a cluster number but didn't tell us
509 * where to put it, give them an error.
510 */
511 if ((function & FAT_GET) && oldcontents == NULL) {
086c1d7e 512 kprintf("fatentry(): get function with no place to put result\n");
984263bc
MD
513 return (EINVAL);
514 }
515#endif
516
517 /*
518 * Be sure the requested cluster is in the filesystem.
519 */
520 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster)
521 return (EINVAL);
522
523 byteoffset = FATOFS(pmp, cn);
524 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
54078292 525 error = bread(pmp->pm_devvp, de_bntodoff(pmp, bn), bsize, &bp);
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MD
526 if (error) {
527 brelse(bp);
528 return (error);
529 }
530
531 if (function & FAT_GET) {
532 if (FAT32(pmp))
533 readcn = getulong(&bp->b_data[bo]);
534 else
535 readcn = getushort(&bp->b_data[bo]);
536 if (FAT12(pmp) & (cn & 1))
537 readcn >>= 4;
538 readcn &= pmp->pm_fatmask;
539 /* map reserved fat entries to same values for all fats */
540 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
541 readcn |= ~pmp->pm_fatmask;
542 *oldcontents = readcn;
543 }
544 if (function & FAT_SET) {
545 switch (pmp->pm_fatmask) {
546 case FAT12_MASK:
547 readcn = getushort(&bp->b_data[bo]);
548 if (cn & 1) {
549 readcn &= 0x000f;
550 readcn |= newcontents << 4;
551 } else {
552 readcn &= 0xf000;
553 readcn |= newcontents & 0xfff;
554 }
555 putushort(&bp->b_data[bo], readcn);
556 break;
557 case FAT16_MASK:
558 putushort(&bp->b_data[bo], newcontents);
559 break;
560 case FAT32_MASK:
561 /*
562 * According to spec we have to retain the
563 * high order bits of the fat entry.
564 */
565 readcn = getulong(&bp->b_data[bo]);
566 readcn &= ~FAT32_MASK;
567 readcn |= newcontents & FAT32_MASK;
568 putulong(&bp->b_data[bo], readcn);
569 break;
570 }
571 updatefats(pmp, bp, bn);
572 bp = NULL;
573 pmp->pm_fmod = 1;
574 }
575 if (bp)
576 brelse(bp);
577 return (0);
578}
579
580/*
581 * Update a contiguous cluster chain
582 *
583 * pmp - mount point
584 * start - first cluster of chain
585 * count - number of clusters in chain
586 * fillwith - what to write into fat entry of last cluster
587 */
588static int
4625f023 589fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith)
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MD
590{
591 int error;
592 u_long bn, bo, bsize, byteoffset, readcn, newc;
593 struct buf *bp;
594
595#ifdef MSDOSFS_DEBUG
086c1d7e 596 kprintf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n",
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MD
597 pmp, start, count, fillwith);
598#endif
599 /*
600 * Be sure the clusters are in the filesystem.
601 */
602 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster)
603 return (EINVAL);
604
605 while (count > 0) {
606 byteoffset = FATOFS(pmp, start);
607 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
54078292 608 error = bread(pmp->pm_devvp, de_bntodoff(pmp, bn), bsize, &bp);
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MD
609 if (error) {
610 brelse(bp);
611 return (error);
612 }
613 while (count > 0) {
614 start++;
615 newc = --count > 0 ? start : fillwith;
616 switch (pmp->pm_fatmask) {
617 case FAT12_MASK:
618 readcn = getushort(&bp->b_data[bo]);
619 if (start & 1) {
620 readcn &= 0xf000;
621 readcn |= newc & 0xfff;
622 } else {
623 readcn &= 0x000f;
624 readcn |= newc << 4;
625 }
626 putushort(&bp->b_data[bo], readcn);
627 bo++;
628 if (!(start & 1))
629 bo++;
630 break;
631 case FAT16_MASK:
632 putushort(&bp->b_data[bo], newc);
633 bo += 2;
634 break;
635 case FAT32_MASK:
636 readcn = getulong(&bp->b_data[bo]);
637 readcn &= ~pmp->pm_fatmask;
638 readcn |= newc & pmp->pm_fatmask;
639 putulong(&bp->b_data[bo], readcn);
640 bo += 4;
641 break;
642 }
643 if (bo >= bsize)
644 break;
645 }
646 updatefats(pmp, bp, bn);
647 }
648 pmp->pm_fmod = 1;
649 return (0);
650}
651
652/*
653 * Check the length of a free cluster chain starting at start.
654 *
655 * pmp - mount point
656 * start - start of chain
657 * count - maximum interesting length
658 */
659static int
4625f023 660chainlength(struct msdosfsmount *pmp, u_long start, u_long count)
984263bc
MD
661{
662 u_long idx, max_idx;
663 u_int map;
664 u_long len;
665
666 max_idx = pmp->pm_maxcluster / N_INUSEBITS;
667 idx = start / N_INUSEBITS;
668 start %= N_INUSEBITS;
669 map = pmp->pm_inusemap[idx];
670 map &= ~((1 << start) - 1);
671 if (map) {
672 len = ffs(map) - 1 - start;
673 return (len > count ? count : len);
674 }
675 len = N_INUSEBITS - start;
676 if (len >= count)
677 return (count);
678 while (++idx <= max_idx) {
679 if (len >= count)
680 break;
681 map = pmp->pm_inusemap[idx];
682 if (map) {
683 len += ffs(map) - 1;
684 break;
685 }
686 len += N_INUSEBITS;
687 }
688 return (len > count ? count : len);
689}
690
691/*
692 * Allocate contigous free clusters.
693 *
694 * pmp - mount point.
695 * start - start of cluster chain.
696 * count - number of clusters to allocate.
697 * fillwith - put this value into the fat entry for the
698 * last allocated cluster.
699 * retcluster - put the first allocated cluster's number here.
700 * got - how many clusters were actually allocated.
701 */
702static int
4625f023
CP
703chainalloc(struct msdosfsmount *pmp, u_long start, u_long count,
704 u_long fillwith, u_long *retcluster, u_long *got)
984263bc
MD
705{
706 int error;
707 u_long cl, n;
708
709 for (cl = start, n = count; n-- > 0;)
710 usemap_alloc(pmp, cl++);
711
712 error = fatchain(pmp, start, count, fillwith);
713 if (error != 0)
714 return (error);
715#ifdef MSDOSFS_DEBUG
086c1d7e 716 kprintf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n",
984263bc
MD
717 start, count);
718#endif
719 if (retcluster)
720 *retcluster = start;
721 if (got)
722 *got = count;
723 return (0);
724}
725
726/*
727 * Allocate contiguous free clusters.
728 *
729 * pmp - mount point.
730 * start - preferred start of cluster chain.
731 * count - number of clusters requested.
732 * fillwith - put this value into the fat entry for the
733 * last allocated cluster.
734 * retcluster - put the first allocated cluster's number here.
735 * got - how many clusters were actually allocated.
736 */
737int
4625f023
CP
738clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count,
739 u_long fillwith, u_long *retcluster, u_long *got)
984263bc
MD
740{
741 u_long idx;
742 u_long len, newst, foundl, cn, l;
743 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */
744 u_int map;
745
746#ifdef MSDOSFS_DEBUG
086c1d7e 747 kprintf("clusteralloc(): find %lu clusters\n",count);
984263bc
MD
748#endif
749 if (start) {
750 if ((len = chainlength(pmp, start, count)) >= count)
751 return (chainalloc(pmp, start, count, fillwith, retcluster, got));
752 } else
753 len = 0;
754
755 /*
756 * Start at a (pseudo) random place to maximize cluster runs
757 * under multiple writers.
758 */
cddfb7bb 759 newst = krandom() % (pmp->pm_maxcluster + 1);
984263bc
MD
760 foundl = 0;
761
762 for (cn = newst; cn <= pmp->pm_maxcluster;) {
763 idx = cn / N_INUSEBITS;
764 map = pmp->pm_inusemap[idx];
765 map |= (1 << (cn % N_INUSEBITS)) - 1;
766 if (map != (u_int)-1) {
767 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
768 if ((l = chainlength(pmp, cn, count)) >= count)
769 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
770 if (l > foundl) {
771 foundcn = cn;
772 foundl = l;
773 }
774 cn += l + 1;
775 continue;
776 }
777 cn += N_INUSEBITS - cn % N_INUSEBITS;
778 }
779 for (cn = 0; cn < newst;) {
780 idx = cn / N_INUSEBITS;
781 map = pmp->pm_inusemap[idx];
782 map |= (1 << (cn % N_INUSEBITS)) - 1;
783 if (map != (u_int)-1) {
784 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
785 if ((l = chainlength(pmp, cn, count)) >= count)
786 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
787 if (l > foundl) {
788 foundcn = cn;
789 foundl = l;
790 }
791 cn += l + 1;
792 continue;
793 }
794 cn += N_INUSEBITS - cn % N_INUSEBITS;
795 }
796
797 if (!foundl)
798 return (ENOSPC);
799
800 if (len)
801 return (chainalloc(pmp, start, len, fillwith, retcluster, got));
802 else
803 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got));
804}
805
806
807/*
808 * Free a chain of clusters.
809 *
810 * pmp - address of the msdosfs mount structure for the filesystem
811 * containing the cluster chain to be freed.
812 * startcluster - number of the 1st cluster in the chain of clusters to be
813 * freed.
814 */
815int
4625f023 816freeclusterchain(struct msdosfsmount *pmp, u_long cluster)
984263bc
MD
817{
818 int error;
819 struct buf *bp = NULL;
820 u_long bn, bo, bsize, byteoffset;
821 u_long readcn, lbn = -1;
822
823 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) {
824 byteoffset = FATOFS(pmp, cluster);
825 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
826 if (lbn != bn) {
827 if (bp)
828 updatefats(pmp, bp, lbn);
54078292 829 error = bread(pmp->pm_devvp, de_bntodoff(pmp, bn), bsize, &bp);
984263bc
MD
830 if (error) {
831 brelse(bp);
832 return (error);
833 }
834 lbn = bn;
835 }
836 usemap_free(pmp, cluster);
837 switch (pmp->pm_fatmask) {
838 case FAT12_MASK:
839 readcn = getushort(&bp->b_data[bo]);
840 if (cluster & 1) {
841 cluster = readcn >> 4;
842 readcn &= 0x000f;
843 readcn |= MSDOSFSFREE << 4;
844 } else {
845 cluster = readcn;
846 readcn &= 0xf000;
847 readcn |= MSDOSFSFREE & 0xfff;
848 }
849 putushort(&bp->b_data[bo], readcn);
850 break;
851 case FAT16_MASK:
852 cluster = getushort(&bp->b_data[bo]);
853 putushort(&bp->b_data[bo], MSDOSFSFREE);
854 break;
855 case FAT32_MASK:
856 cluster = getulong(&bp->b_data[bo]);
857 putulong(&bp->b_data[bo],
858 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK));
859 break;
860 }
861 cluster &= pmp->pm_fatmask;
862 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD)
863 cluster |= pmp->pm_fatmask;
864 }
865 if (bp)
866 updatefats(pmp, bp, bn);
867 return (0);
868}
869
870/*
871 * Read in fat blocks looking for free clusters. For every free cluster
872 * found turn off its corresponding bit in the pm_inusemap.
873 */
874int
4625f023 875fillinusemap(struct msdosfsmount *pmp)
984263bc
MD
876{
877 struct buf *bp = NULL;
878 u_long cn, readcn;
879 int error;
880 u_long bn, bo, bsize, byteoffset;
881
882 /*
883 * Mark all clusters in use, we mark the free ones in the fat scan
884 * loop further down.
885 */
886 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++)
887 pmp->pm_inusemap[cn] = (u_int)-1;
888
889 /*
890 * Figure how many free clusters are in the filesystem by ripping
891 * through the fat counting the number of entries whose content is
892 * zero. These represent free clusters.
893 */
894 pmp->pm_freeclustercount = 0;
895 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) {
896 byteoffset = FATOFS(pmp, cn);
897 bo = byteoffset % pmp->pm_fatblocksize;
898 if (!bo || !bp) {
899 /* Read new FAT block */
900 if (bp)
901 brelse(bp);
902 fatblock(pmp, byteoffset, &bn, &bsize, NULL);
54078292 903 error = bread(pmp->pm_devvp, de_bntodoff(pmp, bn), bsize, &bp);
984263bc
MD
904 if (error) {
905 brelse(bp);
906 return (error);
907 }
908 }
909 if (FAT32(pmp))
910 readcn = getulong(&bp->b_data[bo]);
911 else
912 readcn = getushort(&bp->b_data[bo]);
913 if (FAT12(pmp) && (cn & 1))
914 readcn >>= 4;
915 readcn &= pmp->pm_fatmask;
916
917 if (readcn == 0)
918 usemap_free(pmp, cn);
919 }
920 brelse(bp);
921 return (0);
922}
923
924/*
925 * Allocate a new cluster and chain it onto the end of the file.
926 *
927 * dep - the file to extend
928 * count - number of clusters to allocate
929 * bpp - where to return the address of the buf header for the first new
930 * file block
931 * ncp - where to put cluster number of the first newly allocated cluster
932 * If this pointer is 0, do not return the cluster number.
933 * flags - see fat.h
934 *
935 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of
936 * the de_flag field of the denode and it does not change the de_FileSize
937 * field. This is left for the caller to do.
938 */
939int
4625f023
CP
940extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp,
941 int flags)
984263bc
MD
942{
943 int error;
944 u_long frcn;
945 u_long cn, got;
946 struct msdosfsmount *pmp = dep->de_pmp;
947 struct buf *bp;
948
949 /*
950 * Don't try to extend the root directory
951 */
952 if (dep->de_StartCluster == MSDOSFSROOT
953 && (dep->de_Attributes & ATTR_DIRECTORY)) {
086c1d7e 954 kprintf("extendfile(): attempt to extend root directory\n");
984263bc
MD
955 return (ENOSPC);
956 }
957
958 /*
959 * If the "file's last cluster" cache entry is empty, and the file
960 * is not empty, then fill the cache entry by calling pcbmap().
961 */
962 fc_fileextends++;
963 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY &&
964 dep->de_StartCluster != 0) {
965 fc_lfcempty++;
4afd80f1 966 error = pcbmap(dep, 0xffff, NULL, &cn, NULL);
984263bc
MD
967 /* we expect it to return E2BIG */
968 if (error != E2BIG)
969 return (error);
970 }
971
972 while (count > 0) {
973 /*
974 * Allocate a new cluster chain and cat onto the end of the
975 * file. * If the file is empty we make de_StartCluster point
976 * to the new block. Note that de_StartCluster being 0 is
977 * sufficient to be sure the file is empty since we exclude
978 * attempts to extend the root directory above, and the root
979 * dir is the only file with a startcluster of 0 that has
980 * blocks allocated (sort of).
981 */
982 if (dep->de_StartCluster == 0)
983 cn = 0;
984 else
985 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1;
986 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got);
987 if (error)
988 return (error);
989
990 count -= got;
991
992 /*
993 * Give them the filesystem relative cluster number if they want
994 * it.
995 */
996 if (ncp) {
997 *ncp = cn;
998 ncp = NULL;
999 }
1000
1001 if (dep->de_StartCluster == 0) {
1002 dep->de_StartCluster = cn;
1003 frcn = 0;
1004 } else {
1005 error = fatentry(FAT_SET, pmp,
1006 dep->de_fc[FC_LASTFC].fc_fsrcn,
1007 0, cn);
1008 if (error) {
1009 clusterfree(pmp, cn, NULL);
1010 return (error);
1011 }
1012 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1;
1013 }
1014
1015 /*
4afd80f1
MD
1016 * Update the "last cluster of the file" entry in the
1017 * denode's fat cache.
984263bc
MD
1018 */
1019 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1);
1020
1021 if (flags & DE_CLEAR) {
1022 while (got-- > 0) {
1023 /*
1024 * Get the buf header for the new block of the file.
1025 */
54078292
MD
1026 if (dep->de_Attributes & ATTR_DIRECTORY) {
1027 bp = getblk(pmp->pm_devvp,
4afd80f1 1028 xcntodoff(pmp, cn),
54078292 1029 pmp->pm_bpcluster, 0, 0);
4afd80f1 1030 ++cn;
54078292
MD
1031 } else {
1032 daddr_t dblkno;
1033
1034 bp = getblk(DETOV(dep),
4afd80f1 1035 de_cn2doff(pmp, frcn),
984263bc 1036 pmp->pm_bpcluster, 0, 0);
4afd80f1 1037 ++frcn;
984263bc
MD
1038 /*
1039 * Do the bmap now, as in msdosfs_write
1040 */
1041 if (pcbmap(dep,
54078292 1042 de_bn2cn(pmp, de_off2bn(pmp, bp->b_bio1.bio_offset)),
4afd80f1 1043 &dblkno, NULL, NULL)) {
54078292
MD
1044 bp->b_bio2.bio_offset = NOOFFSET;
1045 } else {
4afd80f1 1046 bp->b_bio2.bio_offset = de_bntodoff(pmp, dblkno);
81b5c339 1047 }
54078292 1048 if (bp->b_bio2.bio_offset == NOOFFSET)
984263bc
MD
1049 panic("extendfile: pcbmap");
1050 }
1051 clrbuf(bp);
1052 if (bpp) {
1053 *bpp = bp;
1054 bpp = NULL;
1055 } else
1056 bdwrite(bp);
1057 }
1058 }
1059 }
1060
1061 return (0);
1062}