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1.1 nbrk 1: /* $OpenBSD: msdosfs_fat.c,v 1.19 2006/12/16 12:44:05 krw Exp $ */
2: /* $NetBSD: msdosfs_fat.c,v 1.26 1997/10/17 11:24:02 ws Exp $ */
3:
4: /*-
5: * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
6: * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
7: * All rights reserved.
8: * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
9: *
10: * Redistribution and use in source and binary forms, with or without
11: * modification, are permitted provided that the following conditions
12: * are met:
13: * 1. Redistributions of source code must retain the above copyright
14: * notice, this list of conditions and the following disclaimer.
15: * 2. Redistributions in binary form must reproduce the above copyright
16: * notice, this list of conditions and the following disclaimer in the
17: * documentation and/or other materials provided with the distribution.
18: * 3. All advertising materials mentioning features or use of this software
19: * must display the following acknowledgement:
20: * This product includes software developed by TooLs GmbH.
21: * 4. The name of TooLs GmbH may not be used to endorse or promote products
22: * derived from this software without specific prior written permission.
23: *
24: * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
25: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
26: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
27: * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
29: * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
30: * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
31: * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
32: * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
33: * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34: */
35: /*
36: * Written by Paul Popelka (paulp@uts.amdahl.com)
37: *
38: * You can do anything you want with this software, just don't say you wrote
39: * it, and don't remove this notice.
40: *
41: * This software is provided "as is".
42: *
43: * The author supplies this software to be publicly redistributed on the
44: * understanding that the author is not responsible for the correct
45: * functioning of this software in any circumstances and is not liable for
46: * any damages caused by this software.
47: *
48: * October 1992
49: */
50:
51: /*
52: * kernel include files.
53: */
54: #include <sys/param.h>
55: #include <sys/systm.h>
56: #include <sys/buf.h>
57: #include <sys/file.h>
58: #include <sys/namei.h>
59: #include <sys/mount.h> /* to define statfs structure */
60: #include <sys/vnode.h> /* to define vattr structure */
61: #include <sys/errno.h>
62: #include <sys/dirent.h>
63:
64: /*
65: * msdosfs include files.
66: */
67: #include <msdosfs/bpb.h>
68: #include <msdosfs/msdosfsmount.h>
69: #include <msdosfs/direntry.h>
70: #include <msdosfs/denode.h>
71: #include <msdosfs/fat.h>
72:
73: /*
74: * Fat cache stats.
75: */
76: int fc_fileextends; /* # of file extends */
77: int fc_lfcempty; /* # of time last file cluster cache entry
78: * was empty */
79: int fc_bmapcalls; /* # of times pcbmap was called */
80:
81: #define LMMAX 20
82: int fc_lmdistance[LMMAX]; /* counters for how far off the last
83: * cluster mapped entry was. */
84: int fc_largedistance; /* off by more than LMMAX */
85:
86: static void fatblock(struct msdosfsmount *, uint32_t, uint32_t *, uint32_t *,
87: uint32_t *);
88: void updatefats(struct msdosfsmount *, struct buf *, uint32_t);
89: static __inline void usemap_free(struct msdosfsmount *, uint32_t);
90: static __inline void usemap_alloc(struct msdosfsmount *, uint32_t);
91: static int fatchain(struct msdosfsmount *, uint32_t, uint32_t, uint32_t);
92: int chainlength(struct msdosfsmount *, uint32_t, uint32_t);
93: int chainalloc(struct msdosfsmount *, uint32_t, uint32_t, uint32_t, uint32_t *,
94: uint32_t *);
95:
96: static void
97: fatblock(pmp, ofs, bnp, sizep, bop)
98: struct msdosfsmount *pmp;
99: uint32_t ofs;
100: uint32_t *bnp;
101: uint32_t *sizep;
102: uint32_t *bop;
103: {
104: uint32_t bn, size;
105:
106: bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec;
107: size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) * DEV_BSIZE;
108: bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs;
109:
110: if (bnp)
111: *bnp = bn;
112: if (sizep)
113: *sizep = size;
114: if (bop)
115: *bop = ofs % pmp->pm_fatblocksize;
116: }
117:
118: /*
119: * Map the logical cluster number of a file into a physical disk sector
120: * that is filesystem relative.
121: *
122: * dep - address of denode representing the file of interest
123: * findcn - file relative cluster whose filesystem relative cluster number
124: * and/or block number are/is to be found
125: * bnp - address of where to place the file system relative block number.
126: * If this pointer is null then don't return this quantity.
127: * cnp - address of where to place the file system relative cluster number.
128: * If this pointer is null then don't return this quantity.
129: *
130: * NOTE: Either bnp or cnp must be non-null.
131: * This function has one side effect. If the requested file relative cluster
132: * is beyond the end of file, then the actual number of clusters in the file
133: * is returned in *cnp. This is useful for determining how long a directory is.
134: * If cnp is null, nothing is returned.
135: */
136: int
137: pcbmap(dep, findcn, bnp, cnp, sp)
138: struct denode *dep;
139: uint32_t findcn; /* file relative cluster to get */
140: daddr64_t *bnp; /* returned filesys relative blk number */
141: uint32_t *cnp; /* returned cluster number */
142: int *sp; /* returned block size */
143: {
144: int error;
145: uint32_t i;
146: uint32_t cn;
147: uint32_t prevcn = 0; /* XXX: prevcn could be used uninitialized */
148: uint32_t byteoffset;
149: uint32_t bn;
150: uint32_t bo;
151: struct buf *bp = NULL;
152: uint32_t bp_bn = -1;
153: struct msdosfsmount *pmp = dep->de_pmp;
154: uint32_t bsize;
155:
156: fc_bmapcalls++;
157:
158: /*
159: * If they don't give us someplace to return a value then don't
160: * bother doing anything.
161: */
162: if (bnp == NULL && cnp == NULL && sp == NULL)
163: return (0);
164:
165: cn = dep->de_StartCluster;
166: /*
167: * The "file" that makes up the root directory is contiguous,
168: * permanently allocated, of fixed size, and is not made up of
169: * clusters. If the cluster number is beyond the end of the root
170: * directory, then return the number of clusters in the file.
171: */
172: if (cn == MSDOSFSROOT) {
173: if (dep->de_Attributes & ATTR_DIRECTORY) {
174: if (de_cn2off(pmp, findcn) >= dep->de_FileSize) {
175: if (cnp)
176: *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize);
177: return (E2BIG);
178: }
179: if (bnp)
180: *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn);
181: if (cnp)
182: *cnp = MSDOSFSROOT;
183: if (sp)
184: *sp = min(pmp->pm_bpcluster,
185: dep->de_FileSize - de_cn2off(pmp, findcn));
186: return (0);
187: } else { /* just an empty file */
188: if (cnp)
189: *cnp = 0;
190: return (E2BIG);
191: }
192: }
193:
194: /*
195: * All other files do I/O in cluster sized blocks
196: */
197: if (sp)
198: *sp = pmp->pm_bpcluster;
199:
200: /*
201: * Rummage around in the fat cache, maybe we can avoid tromping
202: * thru every fat entry for the file. And, keep track of how far
203: * off the cache was from where we wanted to be.
204: */
205: i = 0;
206: fc_lookup(dep, findcn, &i, &cn);
207: if ((bn = findcn - i) >= LMMAX)
208: fc_largedistance++;
209: else
210: fc_lmdistance[bn]++;
211:
212: /*
213: * Handle all other files or directories the normal way.
214: */
215: for (; i < findcn; i++) {
216: /*
217: * Stop with all reserved clusters, not just with EOF.
218: */
219: if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
220: goto hiteof;
221: byteoffset = FATOFS(pmp, cn);
222: fatblock(pmp, byteoffset, &bn, &bsize, &bo);
223: if (bn != bp_bn) {
224: if (bp)
225: brelse(bp);
226: error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
227: if (error) {
228: brelse(bp);
229: return (error);
230: }
231: bp_bn = bn;
232: }
233: prevcn = cn;
234: if (bo >= bsize) {
235: if (bp)
236: brelse(bp);
237: return (EIO);
238: }
239: if (FAT32(pmp))
240: cn = getulong(&bp->b_data[bo]);
241: else
242: cn = getushort(&bp->b_data[bo]);
243: if (FAT12(pmp) && (prevcn & 1))
244: cn >>= 4;
245: cn &= pmp->pm_fatmask;
246:
247: /*
248: * Force the special cluster numbers
249: * to be the same for all cluster sizes
250: * to let the rest of msdosfs handle
251: * all cases the same.
252: */
253: if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
254: cn |= ~pmp->pm_fatmask;
255: }
256:
257: if (!MSDOSFSEOF(pmp, cn)) {
258: if (bp)
259: brelse(bp);
260: if (bnp)
261: *bnp = cntobn(pmp, cn);
262: if (cnp)
263: *cnp = cn;
264: fc_setcache(dep, FC_LASTMAP, i, cn);
265: return (0);
266: }
267:
268: hiteof:;
269: if (cnp)
270: *cnp = i;
271: if (bp)
272: brelse(bp);
273: /* update last file cluster entry in the fat cache */
274: fc_setcache(dep, FC_LASTFC, i - 1, prevcn);
275: return (E2BIG);
276: }
277:
278: /*
279: * Find the closest entry in the fat cache to the cluster we are looking
280: * for.
281: */
282: void
283: fc_lookup(dep, findcn, frcnp, fsrcnp)
284: struct denode *dep;
285: uint32_t findcn;
286: uint32_t *frcnp;
287: uint32_t *fsrcnp;
288: {
289: int i;
290: uint32_t cn;
291: struct fatcache *closest = 0;
292:
293: for (i = 0; i < FC_SIZE; i++) {
294: cn = dep->de_fc[i].fc_frcn;
295: if (cn != FCE_EMPTY && cn <= findcn) {
296: if (closest == 0 || cn > closest->fc_frcn)
297: closest = &dep->de_fc[i];
298: }
299: }
300: if (closest) {
301: *frcnp = closest->fc_frcn;
302: *fsrcnp = closest->fc_fsrcn;
303: }
304: }
305:
306: /*
307: * Purge the fat cache in denode dep of all entries relating to file
308: * relative cluster frcn and beyond.
309: */
310: void
311: fc_purge(dep, frcn)
312: struct denode *dep;
313: u_int frcn;
314: {
315: int i;
316: struct fatcache *fcp;
317:
318: fcp = dep->de_fc;
319: for (i = 0; i < FC_SIZE; i++, fcp++) {
320: if (fcp->fc_frcn >= frcn)
321: fcp->fc_frcn = FCE_EMPTY;
322: }
323: }
324:
325: /*
326: * Update the fat.
327: * If mirroring the fat, update all copies, with the first copy as last.
328: * Else update only the current fat (ignoring the others).
329: *
330: * pmp - msdosfsmount structure for filesystem to update
331: * bp - addr of modified fat block
332: * fatbn - block number relative to begin of filesystem of the modified fat block.
333: */
334: void
335: updatefats(pmp, bp, fatbn)
336: struct msdosfsmount *pmp;
337: struct buf *bp;
338: uint32_t fatbn;
339: {
340: int i;
341: struct buf *bpn;
342:
343: #ifdef MSDOSFS_DEBUG
344: printf("updatefats(pmp %08, buf %x, fatbn %ld)\n", pmp, bp, fatbn);
345: #endif
346:
347: /*
348: * If we have an FSInfo block, update it.
349: */
350: if (pmp->pm_fsinfo) {
351: uint32_t cn = pmp->pm_nxtfree;
352:
353: if (pmp->pm_freeclustercount
354: && (pmp->pm_inusemap[cn / N_INUSEBITS]
355: & (1 << (cn % N_INUSEBITS)))) {
356: /*
357: * The cluster indicated in FSInfo isn't free
358: * any longer. Got get a new free one.
359: */
360: for (cn = 0; cn < pmp->pm_maxcluster; cn++)
361: if (pmp->pm_inusemap[cn / N_INUSEBITS] != (u_int)-1)
362: break;
363: pmp->pm_nxtfree = cn
364: + ffs(pmp->pm_inusemap[cn / N_INUSEBITS]
365: ^ (u_int)-1) - 1;
366: }
367: if (bread(pmp->pm_devvp, pmp->pm_fsinfo, fsi_size(pmp), NOCRED,
368: &bpn) != 0) {
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: */
440: static __inline void
441: usemap_alloc(pmp, cn)
442: struct msdosfsmount *pmp;
443: uint32_t cn;
444: {
445:
446: pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS);
447: pmp->pm_freeclustercount--;
448: }
449:
450: static __inline void
451: usemap_free(pmp, cn)
452: struct msdosfsmount *pmp;
453: uint32_t cn;
454: {
455:
456: pmp->pm_freeclustercount++;
457: pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS));
458: }
459:
460: int
461: clusterfree(pmp, cluster, oldcnp)
462: struct msdosfsmount *pmp;
463: uint32_t cluster;
464: uint32_t *oldcnp;
465: {
466: int error;
467: uint32_t 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: */
504: int
505: fatentry(function, pmp, cn, oldcontents, newcontents)
506: int function;
507: struct msdosfsmount *pmp;
508: uint32_t cn;
509: uint32_t *oldcontents;
510: uint32_t newcontents;
511: {
512: int error;
513: uint32_t readcn;
514: uint32_t bn, bo, bsize, byteoffset;
515: struct buf *bp;
516:
517: #ifdef MSDOSFS_DEBUG
518: printf("fatentry(func %d, pmp %08x, clust %d, oldcon %08x, newcon %d)\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);
549: if ((error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp)) != 0) {
550: brelse(bp);
551: return (error);
552: }
553:
554: if (function & FAT_GET) {
555: if (FAT32(pmp))
556: readcn = getulong(&bp->b_data[bo]);
557: else
558: readcn = getushort(&bp->b_data[bo]);
559: if (FAT12(pmp) && (cn & 1))
560: readcn >>= 4;
561: readcn &= pmp->pm_fatmask;
562: /* map reserved fat entries to same values for all fats */
563: if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
564: readcn |= ~pmp->pm_fatmask;
565: *oldcontents = readcn;
566: }
567: if (function & FAT_SET) {
568: switch (pmp->pm_fatmask) {
569: case FAT12_MASK:
570: readcn = getushort(&bp->b_data[bo]);
571: if (cn & 1) {
572: readcn &= 0x000f;
573: readcn |= newcontents << 4;
574: } else {
575: readcn &= 0xf000;
576: readcn |= newcontents & 0xfff;
577: }
578: putushort(&bp->b_data[bo], readcn);
579: break;
580: case FAT16_MASK:
581: putushort(&bp->b_data[bo], newcontents);
582: break;
583: case FAT32_MASK:
584: /*
585: * According to spec we have to retain the
586: * high order bits of the fat entry.
587: */
588: readcn = getulong(&bp->b_data[bo]);
589: readcn &= ~FAT32_MASK;
590: readcn |= newcontents & FAT32_MASK;
591: putulong(&bp->b_data[bo], readcn);
592: break;
593: }
594: updatefats(pmp, bp, bn);
595: bp = NULL;
596: pmp->pm_fmod = 1;
597: }
598: if (bp)
599: brelse(bp);
600: return (0);
601: }
602:
603: /*
604: * Update a contiguous cluster chain
605: *
606: * pmp - mount point
607: * start - first cluster of chain
608: * count - number of clusters in chain
609: * fillwith - what to write into fat entry of last cluster
610: */
611: static int
612: fatchain(pmp, start, count, fillwith)
613: struct msdosfsmount *pmp;
614: uint32_t start;
615: uint32_t count;
616: uint32_t fillwith;
617: {
618: int error;
619: uint32_t bn, bo, bsize, byteoffset, readcn, newc;
620: struct buf *bp;
621:
622: #ifdef MSDOSFS_DEBUG
623: printf("fatchain(pmp %08x, start %d, count %d, fillwith %d)\n",
624: pmp, start, count, fillwith);
625: #endif
626: /*
627: * Be sure the clusters are in the filesystem.
628: */
629: if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster)
630: return (EINVAL);
631:
632: while (count > 0) {
633: byteoffset = FATOFS(pmp, start);
634: fatblock(pmp, byteoffset, &bn, &bsize, &bo);
635: error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
636: if (error) {
637: brelse(bp);
638: return (error);
639: }
640: while (count > 0) {
641: start++;
642: newc = --count > 0 ? start : fillwith;
643: switch (pmp->pm_fatmask) {
644: case FAT12_MASK:
645: readcn = getushort(&bp->b_data[bo]);
646: if (start & 1) {
647: readcn &= 0xf000;
648: readcn |= newc & 0xfff;
649: } else {
650: readcn &= 0x000f;
651: readcn |= newc << 4;
652: }
653: putushort(&bp->b_data[bo], readcn);
654: bo++;
655: if (!(start & 1))
656: bo++;
657: break;
658: case FAT16_MASK:
659: putushort(&bp->b_data[bo], newc);
660: bo += 2;
661: break;
662: case FAT32_MASK:
663: readcn = getulong(&bp->b_data[bo]);
664: readcn &= ~pmp->pm_fatmask;
665: readcn |= newc & pmp->pm_fatmask;
666: putulong(&bp->b_data[bo], readcn);
667: bo += 4;
668: break;
669: }
670: if (bo >= bsize)
671: break;
672: }
673: updatefats(pmp, bp, bn);
674: }
675: pmp->pm_fmod = 1;
676: return (0);
677: }
678:
679: /*
680: * Check the length of a free cluster chain starting at start.
681: *
682: * pmp - mount point
683: * start - start of chain
684: * count - maximum interesting length
685: */
686: int
687: chainlength(pmp, start, count)
688: struct msdosfsmount *pmp;
689: uint32_t start;
690: uint32_t count;
691: {
692: uint32_t idx, max_idx;
693: u_int map;
694: uint32_t len;
695:
696: max_idx = pmp->pm_maxcluster / N_INUSEBITS;
697: idx = start / N_INUSEBITS;
698: start %= N_INUSEBITS;
699: map = pmp->pm_inusemap[idx];
700: map &= ~((1 << start) - 1);
701: if (map) {
702: len = ffs(map) - 1 - start;
703: return (len > count ? count : len);
704: }
705: len = N_INUSEBITS - start;
706: if (len >= count)
707: return (count);
708: while (++idx <= max_idx) {
709: if (len >= count)
710: break;
711: if ((map = pmp->pm_inusemap[idx]) != 0) {
712: len += ffs(map) - 1;
713: break;
714: }
715: len += N_INUSEBITS;
716: }
717: return (len > count ? count : len);
718: }
719:
720: /*
721: * Allocate contigous free clusters.
722: *
723: * pmp - mount point.
724: * start - start of cluster chain.
725: * count - number of clusters to allocate.
726: * fillwith - put this value into the fat entry for the
727: * last allocated cluster.
728: * retcluster - put the first allocated cluster's number here.
729: * got - how many clusters were actually allocated.
730: */
731: int
732: chainalloc(pmp, start, count, fillwith, retcluster, got)
733: struct msdosfsmount *pmp;
734: uint32_t start;
735: uint32_t count;
736: uint32_t fillwith;
737: uint32_t *retcluster;
738: uint32_t *got;
739: {
740: int error;
741: uint32_t cl, n;
742:
743: for (cl = start, n = count; n-- > 0;)
744: usemap_alloc(pmp, cl++);
745: if ((error = fatchain(pmp, start, count, fillwith)) != 0)
746: return (error);
747: #ifdef MSDOSFS_DEBUG
748: printf("clusteralloc(): allocated cluster chain at %d (%d clusters)\n",
749: start, count);
750: #endif
751: if (retcluster)
752: *retcluster = start;
753: if (got)
754: *got = count;
755: return (0);
756: }
757:
758: /*
759: * Allocate contiguous free clusters.
760: *
761: * pmp - mount point.
762: * start - preferred start of cluster chain.
763: * count - number of clusters requested.
764: * fillwith - put this value into the fat entry for the
765: * last allocated cluster.
766: * retcluster - put the first allocated cluster's number here.
767: * got - how many clusters were actually allocated.
768: */
769: int
770: clusteralloc(pmp, start, count, fillwith, retcluster, got)
771: struct msdosfsmount *pmp;
772: uint32_t start;
773: uint32_t count;
774: uint32_t fillwith;
775: uint32_t *retcluster;
776: uint32_t *got;
777: {
778: uint32_t idx;
779: uint32_t len, newst, foundl, cn, l;
780: uint32_t foundcn = 0; /* XXX: foundcn could be used uninitialized */
781: u_int map;
782:
783: #ifdef MSDOSFS_DEBUG
784: printf("clusteralloc(): find %d clusters\n",count);
785: #endif
786: if (start) {
787: if ((len = chainlength(pmp, start, count)) >= count)
788: return (chainalloc(pmp, start, count, fillwith, retcluster, got));
789: } else {
790: /*
791: * This is a new file, initialize start
792: */
793: struct timeval tv;
794:
795: microtime(&tv);
796: start = (tv.tv_usec >> 10) | tv.tv_usec;
797: len = 0;
798: }
799:
800: /*
801: * Start at a (pseudo) random place to maximize cluster runs
802: * under multiple writers.
803: */
804: newst = (start * 1103515245 + 12345) % (pmp->pm_maxcluster + 1);
805: foundl = 0;
806:
807: for (cn = newst; cn <= pmp->pm_maxcluster;) {
808: idx = cn / N_INUSEBITS;
809: map = pmp->pm_inusemap[idx];
810: map |= (1 << (cn % N_INUSEBITS)) - 1;
811: if (map != (u_int)-1) {
812: cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
813: if ((l = chainlength(pmp, cn, count)) >= count)
814: return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
815: if (l > foundl) {
816: foundcn = cn;
817: foundl = l;
818: }
819: cn += l + 1;
820: continue;
821: }
822: cn += N_INUSEBITS - cn % N_INUSEBITS;
823: }
824: for (cn = 0; cn < newst;) {
825: idx = cn / N_INUSEBITS;
826: map = pmp->pm_inusemap[idx];
827: map |= (1 << (cn % N_INUSEBITS)) - 1;
828: if (map != (u_int)-1) {
829: cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
830: if ((l = chainlength(pmp, cn, count)) >= count)
831: return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
832: if (l > foundl) {
833: foundcn = cn;
834: foundl = l;
835: }
836: cn += l + 1;
837: continue;
838: }
839: cn += N_INUSEBITS - cn % N_INUSEBITS;
840: }
841:
842: if (!foundl)
843: return (ENOSPC);
844:
845: if (len)
846: return (chainalloc(pmp, start, len, fillwith, retcluster, got));
847: else
848: return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got));
849: }
850:
851:
852: /*
853: * Free a chain of clusters.
854: *
855: * pmp - address of the msdosfs mount structure for the filesystem
856: * containing the cluster chain to be freed.
857: * startcluster - number of the 1st cluster in the chain of clusters to be
858: * freed.
859: */
860: int
861: freeclusterchain(pmp, cluster)
862: struct msdosfsmount *pmp;
863: uint32_t cluster;
864: {
865: int error;
866: struct buf *bp = NULL;
867: uint32_t bn, bo, bsize, byteoffset;
868: uint32_t readcn, lbn = -1;
869:
870: while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) {
871: byteoffset = FATOFS(pmp, cluster);
872: fatblock(pmp, byteoffset, &bn, &bsize, &bo);
873: if (lbn != bn) {
874: if (bp)
875: updatefats(pmp, bp, lbn);
876: error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
877: if (error) {
878: brelse(bp);
879: return (error);
880: }
881: lbn = bn;
882: }
883: usemap_free(pmp, cluster);
884: switch (pmp->pm_fatmask) {
885: case FAT12_MASK:
886: readcn = getushort(&bp->b_data[bo]);
887: if (cluster & 1) {
888: cluster = readcn >> 4;
889: readcn &= 0x000f;
890: readcn |= MSDOSFSFREE << 4;
891: } else {
892: cluster = readcn;
893: readcn &= 0xf000;
894: readcn |= MSDOSFSFREE & 0xfff;
895: }
896: putushort(&bp->b_data[bo], readcn);
897: break;
898: case FAT16_MASK:
899: cluster = getushort(&bp->b_data[bo]);
900: putushort(&bp->b_data[bo], MSDOSFSFREE);
901: break;
902: case FAT32_MASK:
903: cluster = getulong(&bp->b_data[bo]);
904: putulong(&bp->b_data[bo],
905: (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK));
906: break;
907: }
908: cluster &= pmp->pm_fatmask;
909: if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD)
910: cluster |= pmp->pm_fatmask;
911: }
912: if (bp)
913: updatefats(pmp, bp, bn);
914: return (0);
915: }
916:
917: /*
918: * Read in fat blocks looking for free clusters. For every free cluster
919: * found turn off its corresponding bit in the pm_inusemap.
920: */
921: int
922: fillinusemap(pmp)
923: struct msdosfsmount *pmp;
924: {
925: struct buf *bp = NULL;
926: uint32_t cn, readcn;
927: int error;
928: uint32_t bn, bo, bsize, byteoffset;
929:
930: /*
931: * Mark all clusters in use, we mark the free ones in the fat scan
932: * loop further down.
933: */
934: for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++)
935: pmp->pm_inusemap[cn] = (u_int)-1;
936:
937: /*
938: * Figure how many free clusters are in the filesystem by ripping
939: * through the fat counting the number of entries whose content is
940: * zero. These represent free clusters.
941: */
942: pmp->pm_freeclustercount = 0;
943: for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) {
944: byteoffset = FATOFS(pmp, cn);
945: bo = byteoffset % pmp->pm_fatblocksize;
946: if (!bo || !bp) {
947: /* Read new FAT block */
948: if (bp)
949: brelse(bp);
950: fatblock(pmp, byteoffset, &bn, &bsize, NULL);
951: error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
952: if (error) {
953: brelse(bp);
954: return (error);
955: }
956: }
957: if (FAT32(pmp))
958: readcn = getulong(&bp->b_data[bo]);
959: else
960: readcn = getushort(&bp->b_data[bo]);
961: if (FAT12(pmp) && (cn & 1))
962: readcn >>= 4;
963: readcn &= pmp->pm_fatmask;
964:
965: if (readcn == 0)
966: usemap_free(pmp, cn);
967: }
968: brelse(bp);
969: return (0);
970: }
971:
972: /*
973: * Allocate a new cluster and chain it onto the end of the file.
974: *
975: * dep - the file to extend
976: * count - number of clusters to allocate
977: * bpp - where to return the address of the buf header for the first new
978: * file block
979: * ncp - where to put cluster number of the first newly allocated cluster
980: * If this pointer is 0, do not return the cluster number.
981: * flags - see fat.h
982: *
983: * NOTE: This function is not responsible for turning on the DE_UPDATE bit of
984: * the de_flag field of the denode and it does not change the de_FileSize
985: * field. This is left for the caller to do.
986: */
987: int
988: extendfile(dep, count, bpp, ncp, flags)
989: struct denode *dep;
990: uint32_t count;
991: struct buf **bpp;
992: uint32_t *ncp;
993: int flags;
994: {
995: int error;
996: uint32_t frcn;
997: uint32_t cn, got;
998: struct msdosfsmount *pmp = dep->de_pmp;
999: struct buf *bp;
1000:
1001: /*
1002: * Don't try to extend the root directory
1003: */
1004: if (dep->de_StartCluster == MSDOSFSROOT
1005: && (dep->de_Attributes & ATTR_DIRECTORY)) {
1006: printf("extendfile(): attempt to extend root directory\n");
1007: return (ENOSPC);
1008: }
1009:
1010: /*
1011: * If the "file's last cluster" cache entry is empty, and the file
1012: * is not empty, then fill the cache entry by calling pcbmap().
1013: */
1014: fc_fileextends++;
1015: if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY &&
1016: dep->de_StartCluster != 0) {
1017: fc_lfcempty++;
1018: error = pcbmap(dep, 0xffff, 0, &cn, 0);
1019: /* we expect it to return E2BIG */
1020: if (error != E2BIG)
1021: return (error);
1022: }
1023:
1024: while (count > 0) {
1025: /*
1026: * Allocate a new cluster chain and cat onto the end of the
1027: * file. * If the file is empty we make de_StartCluster point
1028: * to the new block. Note that de_StartCluster being 0 is
1029: * sufficient to be sure the file is empty since we exclude
1030: * attempts to extend the root directory above, and the root
1031: * dir is the only file with a startcluster of 0 that has
1032: * blocks allocated (sort of).
1033: */
1034: if (dep->de_StartCluster == 0)
1035: cn = 0;
1036: else
1037: cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1;
1038: error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got);
1039: if (error)
1040: return (error);
1041:
1042: count -= got;
1043:
1044: /*
1045: * Give them the filesystem relative cluster number if they want
1046: * it.
1047: */
1048: if (ncp) {
1049: *ncp = cn;
1050: ncp = NULL;
1051: }
1052:
1053: if (dep->de_StartCluster == 0) {
1054: dep->de_StartCluster = cn;
1055: frcn = 0;
1056: } else {
1057: error = fatentry(FAT_SET, pmp,
1058: dep->de_fc[FC_LASTFC].fc_fsrcn,
1059: 0, cn);
1060: if (error) {
1061: clusterfree(pmp, cn, NULL);
1062: return (error);
1063: }
1064: frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1;
1065: }
1066:
1067: /*
1068: * Update the "last cluster of the file" entry in the denode's fat
1069: * cache.
1070: */
1071: fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1);
1072:
1073: if (flags & DE_CLEAR) {
1074: while (got-- > 0) {
1075: /*
1076: * Get the buf header for the new block of the file.
1077: */
1078: if (dep->de_Attributes & ATTR_DIRECTORY)
1079: bp = getblk(pmp->pm_devvp, cntobn(pmp, cn++),
1080: pmp->pm_bpcluster, 0, 0);
1081: else {
1082: bp = getblk(DETOV(dep), de_cn2bn(pmp, frcn++),
1083: pmp->pm_bpcluster, 0, 0);
1084: /*
1085: * Do the bmap now, as in msdosfs_write
1086: */
1087: if (pcbmap(dep,
1088: de_bn2cn(pmp, bp->b_lblkno),
1089: &bp->b_blkno, 0, 0))
1090: bp->b_blkno = -1;
1091: if (bp->b_blkno == -1)
1092: panic("extendfile: pcbmap");
1093: }
1094: clrbuf(bp);
1095: if (bpp) {
1096: *bpp = bp;
1097: bpp = NULL;
1098: } else
1099: bdwrite(bp);
1100: }
1101: }
1102: }
1103:
1104: return (0);
1105: }