2 /* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 ws Exp $ */
5 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
6 * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
8 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
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.
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.
36 * Written by Paul Popelka (paulp@uts.amdahl.com)
38 * You can do anything you want with this software, just don't say you wrote
39 * it, and don't remove this notice.
41 * This software is provided "as is".
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.
51 #include <sys/param.h>
52 #include <sys/systm.h>
54 #include <sys/mount.h>
55 #include <sys/vnode.h>
57 #include <fs/msdosfs/bpb.h>
58 #include <fs/msdosfs/direntry.h>
59 #include <fs/msdosfs/denode.h>
60 #include <fs/msdosfs/fat.h>
61 #include <fs/msdosfs/msdosfsmount.h>
63 static int chainalloc(struct msdosfsmount *pmp, u_long start,
64 u_long count, u_long fillwith, u_long *retcluster,
66 static int chainlength(struct msdosfsmount *pmp, u_long start,
68 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp,
69 u_long *sizep, u_long *bop);
70 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count,
72 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp,
74 static void updatefats(struct msdosfsmount *pmp, struct buf *bp,
77 usemap_alloc(struct msdosfsmount *pmp, u_long cn);
79 usemap_free(struct msdosfsmount *pmp, u_long cn);
80 static int clusteralloc1(struct msdosfsmount *pmp, u_long start,
81 u_long count, u_long fillwith, u_long *retcluster,
85 fatblock(pmp, ofs, bnp, sizep, bop)
86 struct msdosfsmount *pmp;
94 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec;
95 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn)
97 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs;
104 *bop = ofs % pmp->pm_fatblocksize;
108 * Map the logical cluster number of a file into a physical disk sector
109 * that is filesystem relative.
111 * dep - address of denode representing the file of interest
112 * findcn - file relative cluster whose filesystem relative cluster number
113 * and/or block number are/is to be found
114 * bnp - address of where to place the filesystem relative block number.
115 * If this pointer is null then don't return this quantity.
116 * cnp - address of where to place the filesystem relative cluster number.
117 * If this pointer is null then don't return this quantity.
119 * NOTE: Either bnp or cnp must be non-null.
120 * This function has one side effect. If the requested file relative cluster
121 * is beyond the end of file, then the actual number of clusters in the file
122 * is returned in *cnp. This is useful for determining how long a directory is.
123 * If cnp is null, nothing is returned.
126 pcbmap(dep, findcn, bnp, cnp, sp)
128 u_long findcn; /* file relative cluster to get */
129 daddr_t *bnp; /* returned filesys relative blk number */
130 u_long *cnp; /* returned cluster number */
131 int *sp; /* returned block size */
136 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */
140 struct buf *bp = NULL;
142 struct msdosfsmount *pmp = dep->de_pmp;
145 KASSERT(bnp != NULL || cnp != NULL || sp != NULL,
146 ("pcbmap: extra call"));
147 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap");
149 cn = dep->de_StartCluster;
151 * The "file" that makes up the root directory is contiguous,
152 * permanently allocated, of fixed size, and is not made up of
153 * clusters. If the cluster number is beyond the end of the root
154 * directory, then return the number of clusters in the file.
156 if (cn == MSDOSFSROOT) {
157 if (dep->de_Attributes & ATTR_DIRECTORY) {
158 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) {
160 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize);
164 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn);
168 *sp = min(pmp->pm_bpcluster,
169 dep->de_FileSize - de_cn2off(pmp, findcn));
171 } else { /* just an empty file */
179 * All other files do I/O in cluster sized blocks
182 *sp = pmp->pm_bpcluster;
185 * Rummage around in the fat cache, maybe we can avoid tromping
186 * thru every fat entry for the file. And, keep track of how far
187 * off the cache was from where we wanted to be.
190 fc_lookup(dep, findcn, &i, &cn);
193 * Handle all other files or directories the normal way.
195 for (; i < findcn; i++) {
197 * Stop with all reserved clusters, not just with EOF.
199 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
201 byteoffset = FATOFS(pmp, cn);
202 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
206 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
220 cn = getulong(&bp->b_data[bo]);
222 cn = getushort(&bp->b_data[bo]);
223 if (FAT12(pmp) && (prevcn & 1))
225 cn &= pmp->pm_fatmask;
228 * Force the special cluster numbers
229 * to be the same for all cluster sizes
230 * to let the rest of msdosfs handle
231 * all cases the same.
233 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
234 cn |= ~pmp->pm_fatmask;
237 if (!MSDOSFSEOF(pmp, cn)) {
241 *bnp = cntobn(pmp, cn);
244 fc_setcache(dep, FC_LASTMAP, i, cn);
253 /* update last file cluster entry in the fat cache */
254 fc_setcache(dep, FC_LASTFC, i - 1, prevcn);
259 * Find the closest entry in the fat cache to the cluster we are looking
263 fc_lookup(dep, findcn, frcnp, fsrcnp)
271 struct fatcache *closest = 0;
273 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup");
275 for (i = 0; i < FC_SIZE; i++) {
276 cn = dep->de_fc[i].fc_frcn;
277 if (cn != FCE_EMPTY && cn <= findcn) {
278 if (closest == 0 || cn > closest->fc_frcn)
279 closest = &dep->de_fc[i];
283 *frcnp = closest->fc_frcn;
284 *fsrcnp = closest->fc_fsrcn;
289 * Purge the fat cache in denode dep of all entries relating to file
290 * relative cluster frcn and beyond.
298 struct fatcache *fcp;
300 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge");
303 for (i = 0; i < FC_SIZE; i++, fcp++) {
304 if (fcp->fc_frcn >= frcn)
305 fcp->fc_frcn = FCE_EMPTY;
311 * If mirroring the fat, update all copies, with the first copy as last.
312 * Else update only the current fat (ignoring the others).
314 * pmp - msdosfsmount structure for filesystem to update
315 * bp - addr of modified fat block
316 * fatbn - block number relative to begin of filesystem of the modified fat block.
319 updatefats(pmp, bp, fatbn)
320 struct msdosfsmount *pmp;
328 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn);
331 if (pmp->pm_flags & MSDOSFS_FATMIRROR) {
333 * Now copy the block(s) of the modified fat to the other copies of
334 * the fat and write them out. This is faster than reading in the
335 * other fats and then writing them back out. This could tie up
336 * the fat for quite a while. Preventing others from accessing it.
337 * To prevent us from going after the fat quite so much we use
338 * delayed writes, unless they specfied "synchronous" when the
339 * filesystem was mounted. If synch is asked for then use
340 * bwrite()'s and really slow things down.
342 if (fatbn != pmp->pm_fatblk || FAT12(pmp))
348 for (i = 1; i < pmp->pm_FATs; i++) {
349 fatbn += pmp->pm_FATsecs;
350 /* getblk() never fails */
351 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount,
353 bcopy(bp->b_data, bpn->b_data, bp->b_bcount);
354 /* Force the clean bit on in the other copies. */
356 ((u_int8_t *)bpn->b_data)[3] |= 0x80;
357 else if (cleanfat == 32)
358 ((u_int8_t *)bpn->b_data)[7] |= 0x08;
359 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS)
367 * Write out the first (or current) fat last.
369 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS)
376 * Updating entries in 12 bit fats is a pain in the butt.
378 * The following picture shows where nibbles go when moving from a 12 bit
379 * cluster number into the appropriate bytes in the FAT.
381 * byte m byte m+1 byte m+2
382 * +----+----+ +----+----+ +----+----+
383 * | 0 1 | | 2 3 | | 4 5 | FAT bytes
384 * +----+----+ +----+----+ +----+----+
386 * +----+----+----+ +----+----+----+
387 * | 3 0 1 | | 4 5 2 |
388 * +----+----+----+ +----+----+----+
389 * cluster n cluster n+1
391 * Where n is even. m = n + (n >> 2)
395 usemap_alloc(pmp, cn)
396 struct msdosfsmount *pmp;
400 MSDOSFS_ASSERT_MP_LOCKED(pmp);
402 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0,
403 ("usemap_alloc on ro msdosfs mount"));
404 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS)))
405 == 0, ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS,
406 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS]));
407 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS);
408 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little"));
409 pmp->pm_freeclustercount--;
410 pmp->pm_flags |= MSDOSFS_FSIMOD;
415 struct msdosfsmount *pmp;
419 MSDOSFS_ASSERT_MP_LOCKED(pmp);
420 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0,
421 ("usemap_free on ro msdosfs mount"));
422 pmp->pm_freeclustercount++;
423 pmp->pm_flags |= MSDOSFS_FSIMOD;
424 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS)))
425 != 0, ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS,
426 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS]));
427 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS));
431 clusterfree(pmp, cluster, oldcnp)
432 struct msdosfsmount *pmp;
439 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE);
443 * If the cluster was successfully marked free, then update
444 * the count of free clusters, and turn off the "allocated"
445 * bit in the "in use" cluster bit map.
447 MSDOSFS_LOCK_MP(pmp);
448 usemap_free(pmp, cluster);
449 MSDOSFS_UNLOCK_MP(pmp);
456 * Get or Set or 'Get and Set' the cluster'th entry in the fat.
458 * function - whether to get or set a fat entry
459 * pmp - address of the msdosfsmount structure for the filesystem
460 * whose fat is to be manipulated.
461 * cn - which cluster is of interest
462 * oldcontents - address of a word that is to receive the contents of the
463 * cluster'th entry if this is a get function
464 * newcontents - the new value to be written into the cluster'th element of
465 * the fat if this is a set function.
467 * This function can also be used to free a cluster by setting the fat entry
468 * for a cluster to 0.
470 * All copies of the fat are updated if this is a set function. NOTE: If
471 * fatentry() marks a cluster as free it does not update the inusemap in
472 * the msdosfsmount structure. This is left to the caller.
475 fatentry(function, pmp, cn, oldcontents, newcontents)
477 struct msdosfsmount *pmp;
484 u_long bn, bo, bsize, byteoffset;
488 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n",
489 function, pmp, cn, oldcontents, newcontents);
494 * Be sure they asked us to do something.
496 if ((function & (FAT_SET | FAT_GET)) == 0) {
498 printf("fatentry(): function code doesn't specify get or set\n");
504 * If they asked us to return a cluster number but didn't tell us
505 * where to put it, give them an error.
507 if ((function & FAT_GET) && oldcontents == NULL) {
509 printf("fatentry(): get function with no place to put result\n");
516 * Be sure the requested cluster is in the filesystem.
518 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster)
521 byteoffset = FATOFS(pmp, cn);
522 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
523 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
529 if (function & FAT_GET) {
531 readcn = getulong(&bp->b_data[bo]);
533 readcn = getushort(&bp->b_data[bo]);
534 if (FAT12(pmp) & (cn & 1))
536 readcn &= pmp->pm_fatmask;
537 /* map reserved fat entries to same values for all fats */
538 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
539 readcn |= ~pmp->pm_fatmask;
540 *oldcontents = readcn;
542 if (function & FAT_SET) {
543 switch (pmp->pm_fatmask) {
545 readcn = getushort(&bp->b_data[bo]);
548 readcn |= newcontents << 4;
551 readcn |= newcontents & 0xfff;
553 putushort(&bp->b_data[bo], readcn);
556 putushort(&bp->b_data[bo], newcontents);
560 * According to spec we have to retain the
561 * high order bits of the fat entry.
563 readcn = getulong(&bp->b_data[bo]);
564 readcn &= ~FAT32_MASK;
565 readcn |= newcontents & FAT32_MASK;
566 putulong(&bp->b_data[bo], readcn);
569 updatefats(pmp, bp, bn);
579 * Update a contiguous cluster chain
582 * start - first cluster of chain
583 * count - number of clusters in chain
584 * fillwith - what to write into fat entry of last cluster
587 fatchain(pmp, start, count, fillwith)
588 struct msdosfsmount *pmp;
594 u_long bn, bo, bsize, byteoffset, readcn, newc;
598 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n",
599 pmp, start, count, fillwith);
602 * Be sure the clusters are in the filesystem.
604 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster)
608 byteoffset = FATOFS(pmp, start);
609 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
610 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
617 newc = --count > 0 ? start : fillwith;
618 switch (pmp->pm_fatmask) {
620 readcn = getushort(&bp->b_data[bo]);
623 readcn |= newc & 0xfff;
628 putushort(&bp->b_data[bo], readcn);
634 putushort(&bp->b_data[bo], newc);
638 readcn = getulong(&bp->b_data[bo]);
639 readcn &= ~pmp->pm_fatmask;
640 readcn |= newc & pmp->pm_fatmask;
641 putulong(&bp->b_data[bo], readcn);
648 updatefats(pmp, bp, bn);
655 * Check the length of a free cluster chain starting at start.
658 * start - start of chain
659 * count - maximum interesting length
662 chainlength(pmp, start, count)
663 struct msdosfsmount *pmp;
671 MSDOSFS_ASSERT_MP_LOCKED(pmp);
673 max_idx = pmp->pm_maxcluster / N_INUSEBITS;
674 idx = start / N_INUSEBITS;
675 start %= N_INUSEBITS;
676 map = pmp->pm_inusemap[idx];
677 map &= ~((1 << start) - 1);
679 len = ffs(map) - 1 - start;
680 return (len > count ? count : len);
682 len = N_INUSEBITS - start;
685 while (++idx <= max_idx) {
688 map = pmp->pm_inusemap[idx];
695 return (len > count ? count : len);
699 * Allocate contigous free clusters.
702 * start - start of cluster chain.
703 * count - number of clusters to allocate.
704 * fillwith - put this value into the fat entry for the
705 * last allocated cluster.
706 * retcluster - put the first allocated cluster's number here.
707 * got - how many clusters were actually allocated.
710 chainalloc(pmp, start, count, fillwith, retcluster, got)
711 struct msdosfsmount *pmp;
721 MSDOSFS_ASSERT_MP_LOCKED(pmp);
722 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0,
723 ("chainalloc on ro msdosfs mount"));
725 for (cl = start, n = count; n-- > 0;)
726 usemap_alloc(pmp, cl++);
727 pmp->pm_nxtfree = start + count;
728 if (pmp->pm_nxtfree > pmp->pm_maxcluster)
729 pmp->pm_nxtfree = CLUST_FIRST;
730 pmp->pm_flags |= MSDOSFS_FSIMOD;
731 error = fatchain(pmp, start, count, fillwith);
735 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n",
746 * Allocate contiguous free clusters.
749 * start - preferred start of cluster chain.
750 * count - number of clusters requested.
751 * fillwith - put this value into the fat entry for the
752 * last allocated cluster.
753 * retcluster - put the first allocated cluster's number here.
754 * got - how many clusters were actually allocated.
757 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count,
758 u_long fillwith, u_long *retcluster, u_long *got)
762 MSDOSFS_LOCK_MP(pmp);
763 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got);
764 MSDOSFS_UNLOCK_MP(pmp);
769 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count,
770 u_long fillwith, u_long *retcluster, u_long *got)
773 u_long len, newst, foundl, cn, l;
774 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */
777 MSDOSFS_ASSERT_MP_LOCKED(pmp);
780 printf("clusteralloc(): find %lu clusters\n", count);
783 if ((len = chainlength(pmp, start, count)) >= count)
784 return (chainalloc(pmp, start, count, fillwith, retcluster, got));
788 newst = pmp->pm_nxtfree;
791 for (cn = newst; cn <= pmp->pm_maxcluster;) {
792 idx = cn / N_INUSEBITS;
793 map = pmp->pm_inusemap[idx];
794 map |= (1 << (cn % N_INUSEBITS)) - 1;
795 if (map != (u_int)-1) {
796 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
797 if ((l = chainlength(pmp, cn, count)) >= count)
798 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
806 cn += N_INUSEBITS - cn % N_INUSEBITS;
808 for (cn = 0; cn < newst;) {
809 idx = cn / N_INUSEBITS;
810 map = pmp->pm_inusemap[idx];
811 map |= (1 << (cn % N_INUSEBITS)) - 1;
812 if (map != (u_int)-1) {
813 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
814 if ((l = chainlength(pmp, cn, count)) >= count)
815 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
823 cn += N_INUSEBITS - cn % N_INUSEBITS;
830 return (chainalloc(pmp, start, len, fillwith, retcluster, got));
832 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got));
837 * Free a chain of clusters.
839 * pmp - address of the msdosfs mount structure for the filesystem
840 * containing the cluster chain to be freed.
841 * startcluster - number of the 1st cluster in the chain of clusters to be
845 freeclusterchain(pmp, cluster)
846 struct msdosfsmount *pmp;
850 struct buf *bp = NULL;
851 u_long bn, bo, bsize, byteoffset;
852 u_long readcn, lbn = -1;
854 MSDOSFS_LOCK_MP(pmp);
855 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) {
856 byteoffset = FATOFS(pmp, cluster);
857 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
860 updatefats(pmp, bp, lbn);
861 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
864 MSDOSFS_UNLOCK_MP(pmp);
869 usemap_free(pmp, cluster);
870 switch (pmp->pm_fatmask) {
872 readcn = getushort(&bp->b_data[bo]);
874 cluster = readcn >> 4;
876 readcn |= MSDOSFSFREE << 4;
880 readcn |= MSDOSFSFREE & 0xfff;
882 putushort(&bp->b_data[bo], readcn);
885 cluster = getushort(&bp->b_data[bo]);
886 putushort(&bp->b_data[bo], MSDOSFSFREE);
889 cluster = getulong(&bp->b_data[bo]);
890 putulong(&bp->b_data[bo],
891 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK));
894 cluster &= pmp->pm_fatmask;
895 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD)
896 cluster |= pmp->pm_fatmask;
899 updatefats(pmp, bp, bn);
900 MSDOSFS_UNLOCK_MP(pmp);
905 * Read in fat blocks looking for free clusters. For every free cluster
906 * found turn off its corresponding bit in the pm_inusemap.
910 struct msdosfsmount *pmp;
912 struct buf *bp = NULL;
915 u_long bn, bo, bsize, byteoffset;
917 MSDOSFS_ASSERT_MP_LOCKED(pmp);
920 * Mark all clusters in use, we mark the free ones in the fat scan
923 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++)
924 pmp->pm_inusemap[cn] = (u_int)-1;
927 * Figure how many free clusters are in the filesystem by ripping
928 * through the fat counting the number of entries whose content is
929 * zero. These represent free clusters.
931 pmp->pm_freeclustercount = 0;
932 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) {
933 byteoffset = FATOFS(pmp, cn);
934 bo = byteoffset % pmp->pm_fatblocksize;
936 /* Read new FAT block */
939 fatblock(pmp, byteoffset, &bn, &bsize, NULL);
940 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
947 readcn = getulong(&bp->b_data[bo]);
949 readcn = getushort(&bp->b_data[bo]);
950 if (FAT12(pmp) && (cn & 1))
952 readcn &= pmp->pm_fatmask;
955 usemap_free(pmp, cn);
963 * Allocate a new cluster and chain it onto the end of the file.
965 * dep - the file to extend
966 * count - number of clusters to allocate
967 * bpp - where to return the address of the buf header for the first new
969 * ncp - where to put cluster number of the first newly allocated cluster
970 * If this pointer is 0, do not return the cluster number.
973 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of
974 * the de_flag field of the denode and it does not change the de_FileSize
975 * field. This is left for the caller to do.
978 extendfile(dep, count, bpp, ncp, flags)
988 struct msdosfsmount *pmp = dep->de_pmp;
993 * Don't try to extend the root directory
995 if (dep->de_StartCluster == MSDOSFSROOT
996 && (dep->de_Attributes & ATTR_DIRECTORY)) {
998 printf("extendfile(): attempt to extend root directory\n");
1004 * If the "file's last cluster" cache entry is empty, and the file
1005 * is not empty, then fill the cache entry by calling pcbmap().
1007 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY &&
1008 dep->de_StartCluster != 0) {
1009 error = pcbmap(dep, 0xffff, 0, &cn, 0);
1010 /* we expect it to return E2BIG */
1015 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn =
1016 dep->de_fc[FC_LASTFC].fc_frcn;
1017 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn =
1018 dep->de_fc[FC_LASTFC].fc_fsrcn;
1021 * Allocate a new cluster chain and cat onto the end of the
1022 * file. * If the file is empty we make de_StartCluster point
1023 * to the new block. Note that de_StartCluster being 0 is
1024 * sufficient to be sure the file is empty since we exclude
1025 * attempts to extend the root directory above, and the root
1026 * dir is the only file with a startcluster of 0 that has
1027 * blocks allocated (sort of).
1029 if (dep->de_StartCluster == 0)
1032 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1;
1033 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got);
1040 * Give them the filesystem relative cluster number if they want
1048 if (dep->de_StartCluster == 0) {
1049 dep->de_StartCluster = cn;
1052 error = fatentry(FAT_SET, pmp,
1053 dep->de_fc[FC_LASTFC].fc_fsrcn,
1056 clusterfree(pmp, cn, NULL);
1059 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1;
1063 * Update the "last cluster of the file" entry in the denode's fat
1066 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1);
1068 if (flags & DE_CLEAR) {
1071 * Get the buf header for the new block of the file.
1073 if (dep->de_Attributes & ATTR_DIRECTORY)
1074 bp = getblk(pmp->pm_devvp,
1076 pmp->pm_bpcluster, 0, 0, 0);
1078 bp = getblk(DETOV(dep),
1080 pmp->pm_bpcluster, 0, 0, 0);
1082 * Do the bmap now, as in msdosfs_write
1088 if (bp->b_blkno == -1)
1089 panic("extendfile: pcbmap");
1091 bp->b_blkno = blkno;
1107 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by
1108 * manipulating the upper bit of the FAT entry for cluster 1. Note that
1109 * this bit is not defined for FAT12 volumes, which are always assumed to
1112 * The fatentry() routine only works on cluster numbers that a file could
1113 * occupy, so it won't manipulate the entry for cluster 1. So we have to do
1114 * it here. The code was stolen from fatentry() and tailored for cluster 1.
1117 * pmp The MS-DOS volume to mark
1118 * dirty Non-zero if the volume should be marked dirty; zero if it
1119 * should be marked clean
1123 * EROFS Volume is read-only
1124 * ? (other errors from called routines)
1127 markvoldirty(struct msdosfsmount *pmp, int dirty)
1130 u_long bn, bo, bsize, byteoffset, fatval;
1134 * FAT12 does not support a "clean" bit, so don't do anything for
1140 /* Can't change the bit on a read-only filesystem. */
1141 if (pmp->pm_flags & MSDOSFSMNT_RONLY)
1145 * Fetch the block containing the FAT entry. It is given by the
1148 byteoffset = FATOFS(pmp, 1);
1149 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
1150 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
1157 * Get the current value of the FAT entry and set/clear the relevant
1158 * bit. Dirty means clear the "clean" bit; clean means set the
1162 /* FAT32 uses bit 27. */
1163 fatval = getulong(&bp->b_data[bo]);
1165 fatval &= 0xF7FFFFFF;
1167 fatval |= 0x08000000;
1168 putulong(&bp->b_data[bo], fatval);
1170 /* Must be FAT16; use bit 15. */
1171 fatval = getushort(&bp->b_data[bo]);
1176 putushort(&bp->b_data[bo], fatval);
1179 /* Write out the modified FAT block synchronously. */
1180 return (bwrite(bp));