proc->thread stage 5: BUF/VFS clearance! Remove the ucred argument from
[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 $ */
3b568787 2/* $DragonFly: src/sys/vfs/msdosfs/msdosfs_fat.c,v 1.3 2003/06/26 05:55:17 dillon Exp $ */
984263bc
MD
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 */
64#include <msdosfs/bpb.h>
65#include <msdosfs/msdosfsmount.h>
66#include <msdosfs/direntry.h>
67#include <msdosfs/denode.h>
68#include <msdosfs/fat.h>
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
83static int chainalloc __P((struct msdosfsmount *pmp, u_long start,
84 u_long count, u_long fillwith,
85 u_long *retcluster, u_long *got));
86static int chainlength __P((struct msdosfsmount *pmp, u_long start,
87 u_long count));
88static void fatblock __P((struct msdosfsmount *pmp, u_long ofs,
89 u_long *bnp, u_long *sizep, u_long *bop));
90static int fatchain __P((struct msdosfsmount *pmp, u_long start,
91 u_long count, u_long fillwith));
92static void fc_lookup __P((struct denode *dep, u_long findcn,
93 u_long *frcnp, u_long *fsrcnp));
94static void updatefats __P((struct msdosfsmount *pmp, struct buf *bp,
95 u_long fatbn));
96static __inline void
97 usemap_alloc __P((struct msdosfsmount *pmp, u_long cn));
98static __inline void
99 usemap_free __P((struct msdosfsmount *pmp, u_long cn));
100
101static void
102fatblock(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 file system relative block number.
132 * If this pointer is null then don't return this quantity.
133 * cnp - address of where to place the file system 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 */
142int
143pcbmap(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);
3b568787 232 error = bread(pmp->pm_devvp, bn, bsize, &bp);
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233 if (error) {
234 brelse(bp);
235 return (error);
236 }
237 bp_bn = bn;
238 }
239 prevcn = cn;
240 if (FAT32(pmp))
241 cn = getulong(&bp->b_data[bo]);
242 else
243 cn = getushort(&bp->b_data[bo]);
244 if (FAT12(pmp) && (prevcn & 1))
245 cn >>= 4;
246 cn &= pmp->pm_fatmask;
247
248 /*
249 * Force the special cluster numbers
250 * to be the same for all cluster sizes
251 * to let the rest of msdosfs handle
252 * all cases the same.
253 */
254 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
255 cn |= ~pmp->pm_fatmask;
256 }
257
258 if (!MSDOSFSEOF(pmp, cn)) {
259 if (bp)
260 brelse(bp);
261 if (bnp)
262 *bnp = cntobn(pmp, cn);
263 if (cnp)
264 *cnp = cn;
265 fc_setcache(dep, FC_LASTMAP, i, cn);
266 return (0);
267 }
268
269hiteof:;
270 if (cnp)
271 *cnp = i;
272 if (bp)
273 brelse(bp);
274 /* update last file cluster entry in the fat cache */
275 fc_setcache(dep, FC_LASTFC, i - 1, prevcn);
276 return (E2BIG);
277}
278
279/*
280 * Find the closest entry in the fat cache to the cluster we are looking
281 * for.
282 */
283static void
284fc_lookup(dep, findcn, frcnp, fsrcnp)
285 struct denode *dep;
286 u_long findcn;
287 u_long *frcnp;
288 u_long *fsrcnp;
289{
290 int i;
291 u_long cn;
292 struct fatcache *closest = 0;
293
294 for (i = 0; i < FC_SIZE; i++) {
295 cn = dep->de_fc[i].fc_frcn;
296 if (cn != FCE_EMPTY && cn <= findcn) {
297 if (closest == 0 || cn > closest->fc_frcn)
298 closest = &dep->de_fc[i];
299 }
300 }
301 if (closest) {
302 *frcnp = closest->fc_frcn;
303 *fsrcnp = closest->fc_fsrcn;
304 }
305}
306
307/*
308 * Purge the fat cache in denode dep of all entries relating to file
309 * relative cluster frcn and beyond.
310 */
311void
312fc_purge(dep, frcn)
313 struct denode *dep;
314 u_int frcn;
315{
316 int i;
317 struct fatcache *fcp;
318
319 fcp = dep->de_fc;
320 for (i = 0; i < FC_SIZE; i++, fcp++) {
321 if (fcp->fc_frcn >= frcn)
322 fcp->fc_frcn = FCE_EMPTY;
323 }
324}
325
326/*
327 * Update the fat.
328 * If mirroring the fat, update all copies, with the first copy as last.
329 * Else update only the current fat (ignoring the others).
330 *
331 * pmp - msdosfsmount structure for filesystem to update
332 * bp - addr of modified fat block
333 * fatbn - block number relative to begin of filesystem of the modified fat block.
334 */
335static void
336updatefats(pmp, bp, fatbn)
337 struct msdosfsmount *pmp;
338 struct buf *bp;
339 u_long fatbn;
340{
341 int i;
342 struct buf *bpn;
343
344#ifdef MSDOSFS_DEBUG
345 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn);
346#endif
347
348 /*
349 * If we have an FSInfo block, update it.
350 */
351 if (pmp->pm_fsinfo) {
352 u_long cn = pmp->pm_nxtfree;
353
354 if (pmp->pm_freeclustercount
355 && (pmp->pm_inusemap[cn / N_INUSEBITS]
356 & (1 << (cn % N_INUSEBITS)))) {
357 /*
358 * The cluster indicated in FSInfo isn't free
359 * any longer. Got get a new free one.
360 */
361 for (cn = 0; cn < pmp->pm_maxcluster; cn += N_INUSEBITS)
362 if (pmp->pm_inusemap[cn / N_INUSEBITS] != (u_int)-1)
363 break;
364 pmp->pm_nxtfree = cn
365 + ffs(pmp->pm_inusemap[cn / N_INUSEBITS]
366 ^ (u_int)-1) - 1;
367 }
3b568787 368 if (bread(pmp->pm_devvp, pmp->pm_fsinfo, fsi_size(pmp), &bpn) != 0) {
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369 /*
370 * Ignore the error, but turn off FSInfo update for the future.
371 */
372 pmp->pm_fsinfo = 0;
373 brelse(bpn);
374 } else {
375 struct fsinfo *fp = (struct fsinfo *)bpn->b_data;
376
377 putulong(fp->fsinfree, pmp->pm_freeclustercount);
378 putulong(fp->fsinxtfree, pmp->pm_nxtfree);
379 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT)
380 bwrite(bpn);
381 else
382 bdwrite(bpn);
383 }
384 }
385
386 if (pmp->pm_flags & MSDOSFS_FATMIRROR) {
387 /*
388 * Now copy the block(s) of the modified fat to the other copies of
389 * the fat and write them out. This is faster than reading in the
390 * other fats and then writing them back out. This could tie up
391 * the fat for quite a while. Preventing others from accessing it.
392 * To prevent us from going after the fat quite so much we use
393 * delayed writes, unless they specfied "synchronous" when the
394 * filesystem was mounted. If synch is asked for then use
395 * bwrite()'s and really slow things down.
396 */
397 for (i = 1; i < pmp->pm_FATs; i++) {
398 fatbn += pmp->pm_FATsecs;
399 /* getblk() never fails */
400 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 0, 0);
401 bcopy(bp->b_data, bpn->b_data, bp->b_bcount);
402 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT)
403 bwrite(bpn);
404 else
405 bdwrite(bpn);
406 }
407 }
408
409 /*
410 * Write out the first (or current) fat last.
411 */
412 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT)
413 bwrite(bp);
414 else
415 bdwrite(bp);
416 /*
417 * Maybe update fsinfo sector here?
418 */
419}
420
421/*
422 * Updating entries in 12 bit fats is a pain in the butt.
423 *
424 * The following picture shows where nibbles go when moving from a 12 bit
425 * cluster number into the appropriate bytes in the FAT.
426 *
427 * byte m byte m+1 byte m+2
428 * +----+----+ +----+----+ +----+----+
429 * | 0 1 | | 2 3 | | 4 5 | FAT bytes
430 * +----+----+ +----+----+ +----+----+
431 *
432 * +----+----+----+ +----+----+----+
433 * | 3 0 1 | | 4 5 2 |
434 * +----+----+----+ +----+----+----+
435 * cluster n cluster n+1
436 *
437 * Where n is even. m = n + (n >> 2)
438 *
439 */
440static __inline void
441usemap_alloc(pmp, cn)
442 struct msdosfsmount *pmp;
443 u_long cn;
444{
445
446 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS);
447 pmp->pm_freeclustercount--;
448}
449
450static __inline void
451usemap_free(pmp, cn)
452 struct msdosfsmount *pmp;
453 u_long cn;
454{
455
456 pmp->pm_freeclustercount++;
457 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS));
458}
459
460int
461clusterfree(pmp, cluster, oldcnp)
462 struct msdosfsmount *pmp;
463 u_long cluster;
464 u_long *oldcnp;
465{
466 int error;
467 u_long oldcn;
468
469 usemap_free(pmp, cluster);
470 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE);
471 if (error) {
472 usemap_alloc(pmp, cluster);
473 return (error);
474 }
475 /*
476 * If the cluster was successfully marked free, then update
477 * the count of free clusters, and turn off the "allocated"
478 * bit in the "in use" cluster bit map.
479 */
480 if (oldcnp)
481 *oldcnp = oldcn;
482 return (0);
483}
484
485/*
486 * Get or Set or 'Get and Set' the cluster'th entry in the fat.
487 *
488 * function - whether to get or set a fat entry
489 * pmp - address of the msdosfsmount structure for the filesystem
490 * whose fat is to be manipulated.
491 * cn - which cluster is of interest
492 * oldcontents - address of a word that is to receive the contents of the
493 * cluster'th entry if this is a get function
494 * newcontents - the new value to be written into the cluster'th element of
495 * the fat if this is a set function.
496 *
497 * This function can also be used to free a cluster by setting the fat entry
498 * for a cluster to 0.
499 *
500 * All copies of the fat are updated if this is a set function. NOTE: If
501 * fatentry() marks a cluster as free it does not update the inusemap in
502 * the msdosfsmount structure. This is left to the caller.
503 */
504int
505fatentry(function, pmp, cn, oldcontents, newcontents)
506 int function;
507 struct msdosfsmount *pmp;
508 u_long cn;
509 u_long *oldcontents;
510 u_long newcontents;
511{
512 int error;
513 u_long readcn;
514 u_long bn, bo, bsize, byteoffset;
515 struct buf *bp;
516
517#ifdef MSDOSFS_DEBUG
518 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n",
519 function, pmp, cn, oldcontents, newcontents);
520#endif
521
522#ifdef DIAGNOSTIC
523 /*
524 * Be sure they asked us to do something.
525 */
526 if ((function & (FAT_SET | FAT_GET)) == 0) {
527 printf("fatentry(): function code doesn't specify get or set\n");
528 return (EINVAL);
529 }
530
531 /*
532 * If they asked us to return a cluster number but didn't tell us
533 * where to put it, give them an error.
534 */
535 if ((function & FAT_GET) && oldcontents == NULL) {
536 printf("fatentry(): get function with no place to put result\n");
537 return (EINVAL);
538 }
539#endif
540
541 /*
542 * Be sure the requested cluster is in the filesystem.
543 */
544 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster)
545 return (EINVAL);
546
547 byteoffset = FATOFS(pmp, cn);
548 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
3b568787 549 error = bread(pmp->pm_devvp, bn, bsize, &bp);
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MD
550 if (error) {
551 brelse(bp);
552 return (error);
553 }
554
555 if (function & FAT_GET) {
556 if (FAT32(pmp))
557 readcn = getulong(&bp->b_data[bo]);
558 else
559 readcn = getushort(&bp->b_data[bo]);
560 if (FAT12(pmp) & (cn & 1))
561 readcn >>= 4;
562 readcn &= pmp->pm_fatmask;
563 /* map reserved fat entries to same values for all fats */
564 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
565 readcn |= ~pmp->pm_fatmask;
566 *oldcontents = readcn;
567 }
568 if (function & FAT_SET) {
569 switch (pmp->pm_fatmask) {
570 case FAT12_MASK:
571 readcn = getushort(&bp->b_data[bo]);
572 if (cn & 1) {
573 readcn &= 0x000f;
574 readcn |= newcontents << 4;
575 } else {
576 readcn &= 0xf000;
577 readcn |= newcontents & 0xfff;
578 }
579 putushort(&bp->b_data[bo], readcn);
580 break;
581 case FAT16_MASK:
582 putushort(&bp->b_data[bo], newcontents);
583 break;
584 case FAT32_MASK:
585 /*
586 * According to spec we have to retain the
587 * high order bits of the fat entry.
588 */
589 readcn = getulong(&bp->b_data[bo]);
590 readcn &= ~FAT32_MASK;
591 readcn |= newcontents & FAT32_MASK;
592 putulong(&bp->b_data[bo], readcn);
593 break;
594 }
595 updatefats(pmp, bp, bn);
596 bp = NULL;
597 pmp->pm_fmod = 1;
598 }
599 if (bp)
600 brelse(bp);
601 return (0);
602}
603
604/*
605 * Update a contiguous cluster chain
606 *
607 * pmp - mount point
608 * start - first cluster of chain
609 * count - number of clusters in chain
610 * fillwith - what to write into fat entry of last cluster
611 */
612static int
613fatchain(pmp, start, count, fillwith)
614 struct msdosfsmount *pmp;
615 u_long start;
616 u_long count;
617 u_long fillwith;
618{
619 int error;
620 u_long bn, bo, bsize, byteoffset, readcn, newc;
621 struct buf *bp;
622
623#ifdef MSDOSFS_DEBUG
624 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n",
625 pmp, start, count, fillwith);
626#endif
627 /*
628 * Be sure the clusters are in the filesystem.
629 */
630 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster)
631 return (EINVAL);
632
633 while (count > 0) {
634 byteoffset = FATOFS(pmp, start);
635 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
3b568787 636 error = bread(pmp->pm_devvp, bn, bsize, &bp);
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637 if (error) {
638 brelse(bp);
639 return (error);
640 }
641 while (count > 0) {
642 start++;
643 newc = --count > 0 ? start : fillwith;
644 switch (pmp->pm_fatmask) {
645 case FAT12_MASK:
646 readcn = getushort(&bp->b_data[bo]);
647 if (start & 1) {
648 readcn &= 0xf000;
649 readcn |= newc & 0xfff;
650 } else {
651 readcn &= 0x000f;
652 readcn |= newc << 4;
653 }
654 putushort(&bp->b_data[bo], readcn);
655 bo++;
656 if (!(start & 1))
657 bo++;
658 break;
659 case FAT16_MASK:
660 putushort(&bp->b_data[bo], newc);
661 bo += 2;
662 break;
663 case FAT32_MASK:
664 readcn = getulong(&bp->b_data[bo]);
665 readcn &= ~pmp->pm_fatmask;
666 readcn |= newc & pmp->pm_fatmask;
667 putulong(&bp->b_data[bo], readcn);
668 bo += 4;
669 break;
670 }
671 if (bo >= bsize)
672 break;
673 }
674 updatefats(pmp, bp, bn);
675 }
676 pmp->pm_fmod = 1;
677 return (0);
678}
679
680/*
681 * Check the length of a free cluster chain starting at start.
682 *
683 * pmp - mount point
684 * start - start of chain
685 * count - maximum interesting length
686 */
687static int
688chainlength(pmp, start, count)
689 struct msdosfsmount *pmp;
690 u_long start;
691 u_long count;
692{
693 u_long idx, max_idx;
694 u_int map;
695 u_long len;
696
697 max_idx = pmp->pm_maxcluster / N_INUSEBITS;
698 idx = start / N_INUSEBITS;
699 start %= N_INUSEBITS;
700 map = pmp->pm_inusemap[idx];
701 map &= ~((1 << start) - 1);
702 if (map) {
703 len = ffs(map) - 1 - start;
704 return (len > count ? count : len);
705 }
706 len = N_INUSEBITS - start;
707 if (len >= count)
708 return (count);
709 while (++idx <= max_idx) {
710 if (len >= count)
711 break;
712 map = pmp->pm_inusemap[idx];
713 if (map) {
714 len += ffs(map) - 1;
715 break;
716 }
717 len += N_INUSEBITS;
718 }
719 return (len > count ? count : len);
720}
721
722/*
723 * Allocate contigous free clusters.
724 *
725 * pmp - mount point.
726 * start - start of cluster chain.
727 * count - number of clusters to allocate.
728 * fillwith - put this value into the fat entry for the
729 * last allocated cluster.
730 * retcluster - put the first allocated cluster's number here.
731 * got - how many clusters were actually allocated.
732 */
733static int
734chainalloc(pmp, start, count, fillwith, retcluster, got)
735 struct msdosfsmount *pmp;
736 u_long start;
737 u_long count;
738 u_long fillwith;
739 u_long *retcluster;
740 u_long *got;
741{
742 int error;
743 u_long cl, n;
744
745 for (cl = start, n = count; n-- > 0;)
746 usemap_alloc(pmp, cl++);
747
748 error = fatchain(pmp, start, count, fillwith);
749 if (error != 0)
750 return (error);
751#ifdef MSDOSFS_DEBUG
752 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n",
753 start, count);
754#endif
755 if (retcluster)
756 *retcluster = start;
757 if (got)
758 *got = count;
759 return (0);
760}
761
762/*
763 * Allocate contiguous free clusters.
764 *
765 * pmp - mount point.
766 * start - preferred start of cluster chain.
767 * count - number of clusters requested.
768 * fillwith - put this value into the fat entry for the
769 * last allocated cluster.
770 * retcluster - put the first allocated cluster's number here.
771 * got - how many clusters were actually allocated.
772 */
773int
774clusteralloc(pmp, start, count, fillwith, retcluster, got)
775 struct msdosfsmount *pmp;
776 u_long start;
777 u_long count;
778 u_long fillwith;
779 u_long *retcluster;
780 u_long *got;
781{
782 u_long idx;
783 u_long len, newst, foundl, cn, l;
784 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */
785 u_int map;
786
787#ifdef MSDOSFS_DEBUG
788 printf("clusteralloc(): find %lu clusters\n",count);
789#endif
790 if (start) {
791 if ((len = chainlength(pmp, start, count)) >= count)
792 return (chainalloc(pmp, start, count, fillwith, retcluster, got));
793 } else
794 len = 0;
795
796 /*
797 * Start at a (pseudo) random place to maximize cluster runs
798 * under multiple writers.
799 */
800 newst = random() % (pmp->pm_maxcluster + 1);
801 foundl = 0;
802
803 for (cn = newst; cn <= pmp->pm_maxcluster;) {
804 idx = cn / N_INUSEBITS;
805 map = pmp->pm_inusemap[idx];
806 map |= (1 << (cn % N_INUSEBITS)) - 1;
807 if (map != (u_int)-1) {
808 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
809 if ((l = chainlength(pmp, cn, count)) >= count)
810 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
811 if (l > foundl) {
812 foundcn = cn;
813 foundl = l;
814 }
815 cn += l + 1;
816 continue;
817 }
818 cn += N_INUSEBITS - cn % N_INUSEBITS;
819 }
820 for (cn = 0; cn < newst;) {
821 idx = cn / N_INUSEBITS;
822 map = pmp->pm_inusemap[idx];
823 map |= (1 << (cn % N_INUSEBITS)) - 1;
824 if (map != (u_int)-1) {
825 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
826 if ((l = chainlength(pmp, cn, count)) >= count)
827 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
828 if (l > foundl) {
829 foundcn = cn;
830 foundl = l;
831 }
832 cn += l + 1;
833 continue;
834 }
835 cn += N_INUSEBITS - cn % N_INUSEBITS;
836 }
837
838 if (!foundl)
839 return (ENOSPC);
840
841 if (len)
842 return (chainalloc(pmp, start, len, fillwith, retcluster, got));
843 else
844 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got));
845}
846
847
848/*
849 * Free a chain of clusters.
850 *
851 * pmp - address of the msdosfs mount structure for the filesystem
852 * containing the cluster chain to be freed.
853 * startcluster - number of the 1st cluster in the chain of clusters to be
854 * freed.
855 */
856int
857freeclusterchain(pmp, cluster)
858 struct msdosfsmount *pmp;
859 u_long cluster;
860{
861 int error;
862 struct buf *bp = NULL;
863 u_long bn, bo, bsize, byteoffset;
864 u_long readcn, lbn = -1;
865
866 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) {
867 byteoffset = FATOFS(pmp, cluster);
868 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
869 if (lbn != bn) {
870 if (bp)
871 updatefats(pmp, bp, lbn);
3b568787 872 error = bread(pmp->pm_devvp, bn, bsize, &bp);
984263bc
MD
873 if (error) {
874 brelse(bp);
875 return (error);
876 }
877 lbn = bn;
878 }
879 usemap_free(pmp, cluster);
880 switch (pmp->pm_fatmask) {
881 case FAT12_MASK:
882 readcn = getushort(&bp->b_data[bo]);
883 if (cluster & 1) {
884 cluster = readcn >> 4;
885 readcn &= 0x000f;
886 readcn |= MSDOSFSFREE << 4;
887 } else {
888 cluster = readcn;
889 readcn &= 0xf000;
890 readcn |= MSDOSFSFREE & 0xfff;
891 }
892 putushort(&bp->b_data[bo], readcn);
893 break;
894 case FAT16_MASK:
895 cluster = getushort(&bp->b_data[bo]);
896 putushort(&bp->b_data[bo], MSDOSFSFREE);
897 break;
898 case FAT32_MASK:
899 cluster = getulong(&bp->b_data[bo]);
900 putulong(&bp->b_data[bo],
901 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK));
902 break;
903 }
904 cluster &= pmp->pm_fatmask;
905 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD)
906 cluster |= pmp->pm_fatmask;
907 }
908 if (bp)
909 updatefats(pmp, bp, bn);
910 return (0);
911}
912
913/*
914 * Read in fat blocks looking for free clusters. For every free cluster
915 * found turn off its corresponding bit in the pm_inusemap.
916 */
917int
918fillinusemap(pmp)
919 struct msdosfsmount *pmp;
920{
921 struct buf *bp = NULL;
922 u_long cn, readcn;
923 int error;
924 u_long bn, bo, bsize, byteoffset;
925
926 /*
927 * Mark all clusters in use, we mark the free ones in the fat scan
928 * loop further down.
929 */
930 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++)
931 pmp->pm_inusemap[cn] = (u_int)-1;
932
933 /*
934 * Figure how many free clusters are in the filesystem by ripping
935 * through the fat counting the number of entries whose content is
936 * zero. These represent free clusters.
937 */
938 pmp->pm_freeclustercount = 0;
939 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) {
940 byteoffset = FATOFS(pmp, cn);
941 bo = byteoffset % pmp->pm_fatblocksize;
942 if (!bo || !bp) {
943 /* Read new FAT block */
944 if (bp)
945 brelse(bp);
946 fatblock(pmp, byteoffset, &bn, &bsize, NULL);
3b568787 947 error = bread(pmp->pm_devvp, bn, bsize, &bp);
984263bc
MD
948 if (error) {
949 brelse(bp);
950 return (error);
951 }
952 }
953 if (FAT32(pmp))
954 readcn = getulong(&bp->b_data[bo]);
955 else
956 readcn = getushort(&bp->b_data[bo]);
957 if (FAT12(pmp) && (cn & 1))
958 readcn >>= 4;
959 readcn &= pmp->pm_fatmask;
960
961 if (readcn == 0)
962 usemap_free(pmp, cn);
963 }
964 brelse(bp);
965 return (0);
966}
967
968/*
969 * Allocate a new cluster and chain it onto the end of the file.
970 *
971 * dep - the file to extend
972 * count - number of clusters to allocate
973 * bpp - where to return the address of the buf header for the first new
974 * file block
975 * ncp - where to put cluster number of the first newly allocated cluster
976 * If this pointer is 0, do not return the cluster number.
977 * flags - see fat.h
978 *
979 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of
980 * the de_flag field of the denode and it does not change the de_FileSize
981 * field. This is left for the caller to do.
982 */
983int
984extendfile(dep, count, bpp, ncp, flags)
985 struct denode *dep;
986 u_long count;
987 struct buf **bpp;
988 u_long *ncp;
989 int flags;
990{
991 int error;
992 u_long frcn;
993 u_long cn, got;
994 struct msdosfsmount *pmp = dep->de_pmp;
995 struct buf *bp;
996
997 /*
998 * Don't try to extend the root directory
999 */
1000 if (dep->de_StartCluster == MSDOSFSROOT
1001 && (dep->de_Attributes & ATTR_DIRECTORY)) {
1002 printf("extendfile(): attempt to extend root directory\n");
1003 return (ENOSPC);
1004 }
1005
1006 /*
1007 * If the "file's last cluster" cache entry is empty, and the file
1008 * is not empty, then fill the cache entry by calling pcbmap().
1009 */
1010 fc_fileextends++;
1011 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY &&
1012 dep->de_StartCluster != 0) {
1013 fc_lfcempty++;
1014 error = pcbmap(dep, 0xffff, 0, &cn, 0);
1015 /* we expect it to return E2BIG */
1016 if (error != E2BIG)
1017 return (error);
1018 }
1019
1020 while (count > 0) {
1021 /*
1022 * Allocate a new cluster chain and cat onto the end of the
1023 * file. * If the file is empty we make de_StartCluster point
1024 * to the new block. Note that de_StartCluster being 0 is
1025 * sufficient to be sure the file is empty since we exclude
1026 * attempts to extend the root directory above, and the root
1027 * dir is the only file with a startcluster of 0 that has
1028 * blocks allocated (sort of).
1029 */
1030 if (dep->de_StartCluster == 0)
1031 cn = 0;
1032 else
1033 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1;
1034 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got);
1035 if (error)
1036 return (error);
1037
1038 count -= got;
1039
1040 /*
1041 * Give them the filesystem relative cluster number if they want
1042 * it.
1043 */
1044 if (ncp) {
1045 *ncp = cn;
1046 ncp = NULL;
1047 }
1048
1049 if (dep->de_StartCluster == 0) {
1050 dep->de_StartCluster = cn;
1051 frcn = 0;
1052 } else {
1053 error = fatentry(FAT_SET, pmp,
1054 dep->de_fc[FC_LASTFC].fc_fsrcn,
1055 0, cn);
1056 if (error) {
1057 clusterfree(pmp, cn, NULL);
1058 return (error);
1059 }
1060 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1;
1061 }
1062
1063 /*
1064 * Update the "last cluster of the file" entry in the denode's fat
1065 * cache.
1066 */
1067 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1);
1068
1069 if (flags & DE_CLEAR) {
1070 while (got-- > 0) {
1071 /*
1072 * Get the buf header for the new block of the file.
1073 */
1074 if (dep->de_Attributes & ATTR_DIRECTORY)
1075 bp = getblk(pmp->pm_devvp, cntobn(pmp, cn++),
1076 pmp->pm_bpcluster, 0, 0);
1077 else {
1078 bp = getblk(DETOV(dep), de_cn2bn(pmp, frcn++),
1079 pmp->pm_bpcluster, 0, 0);
1080 /*
1081 * Do the bmap now, as in msdosfs_write
1082 */
1083 if (pcbmap(dep,
1084 de_bn2cn(pmp, bp->b_lblkno),
1085 &bp->b_blkno, 0, 0))
1086 bp->b_blkno = -1;
1087 if (bp->b_blkno == -1)
1088 panic("extendfile: pcbmap");
1089 }
1090 clrbuf(bp);
1091 if (bpp) {
1092 *bpp = bp;
1093 bpp = NULL;
1094 } else
1095 bdwrite(bp);
1096 }
1097 }
1098 }
1099
1100 return (0);
1101}