2 /* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 ws Exp $ */
5 * SPDX-License-Identifier: BSD-4-Clause
7 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
8 * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
10 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by TooLs GmbH.
23 * 4. The name of TooLs GmbH may not be used to endorse or promote products
24 * derived from this software without specific prior written permission.
26 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
31 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
32 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
33 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
34 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
35 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38 * Written by Paul Popelka (paulp@uts.amdahl.com)
40 * You can do anything you want with this software, just don't say you wrote
41 * it, and don't remove this notice.
43 * This software is provided "as is".
45 * The author supplies this software to be publicly redistributed on the
46 * understanding that the author is not responsible for the correct
47 * functioning of this software in any circumstances and is not liable for
48 * any damages caused by this software.
53 #include <sys/param.h>
54 #include <sys/systm.h>
56 #include <sys/mount.h>
57 #include <sys/vnode.h>
59 #include <fs/msdosfs/bpb.h>
60 #include <fs/msdosfs/direntry.h>
61 #include <fs/msdosfs/denode.h>
62 #include <fs/msdosfs/fat.h>
63 #include <fs/msdosfs/msdosfsmount.h>
65 #define FULL_RUN ((u_int)0xffffffff)
67 static int chainalloc(struct msdosfsmount *pmp, u_long start,
68 u_long count, u_long fillwith, u_long *retcluster,
70 static int chainlength(struct msdosfsmount *pmp, u_long start,
72 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp,
73 u_long *sizep, u_long *bop);
74 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count,
76 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp,
78 static void updatefats(struct msdosfsmount *pmp, struct buf *bp,
81 usemap_alloc(struct msdosfsmount *pmp, u_long cn);
83 usemap_free(struct msdosfsmount *pmp, u_long cn);
84 static int clusteralloc1(struct msdosfsmount *pmp, u_long start,
85 u_long count, u_long fillwith, u_long *retcluster,
89 fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep,
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.
118 * sp - pointer to returned block size
120 * NOTE: Either bnp or cnp must be non-null.
121 * This function has one side effect. If the requested file relative cluster
122 * is beyond the end of file, then the actual number of clusters in the file
123 * is returned in *cnp. This is useful for determining how long a directory is.
124 * If cnp is null, nothing is returned.
127 pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp)
132 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */
136 struct buf *bp = NULL;
138 struct msdosfsmount *pmp = dep->de_pmp;
141 KASSERT(bnp != NULL || cnp != NULL || sp != NULL,
142 ("pcbmap: extra call"));
143 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap");
145 cn = dep->de_StartCluster;
147 * The "file" that makes up the root directory is contiguous,
148 * permanently allocated, of fixed size, and is not made up of
149 * clusters. If the cluster number is beyond the end of the root
150 * directory, then return the number of clusters in the file.
152 if (cn == MSDOSFSROOT) {
153 if (dep->de_Attributes & ATTR_DIRECTORY) {
154 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) {
156 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize);
160 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn);
164 *sp = min(pmp->pm_bpcluster,
165 dep->de_FileSize - de_cn2off(pmp, findcn));
167 } else { /* just an empty file */
175 * All other files do I/O in cluster sized blocks
178 *sp = pmp->pm_bpcluster;
181 * Rummage around in the FAT cache, maybe we can avoid tromping
182 * through every FAT entry for the file. And, keep track of how far
183 * off the cache was from where we wanted to be.
186 fc_lookup(dep, findcn, &i, &cn);
189 * Handle all other files or directories the normal way.
191 for (; i < findcn; i++) {
193 * Stop with all reserved clusters, not just with EOF.
195 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
197 byteoffset = FATOFS(pmp, cn);
198 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
202 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
216 cn = getulong(&bp->b_data[bo]);
218 cn = getushort(&bp->b_data[bo]);
219 if (FAT12(pmp) && (prevcn & 1))
221 cn &= pmp->pm_fatmask;
224 * Force the special cluster numbers
225 * to be the same for all cluster sizes
226 * to let the rest of msdosfs handle
227 * all cases the same.
229 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
230 cn |= ~pmp->pm_fatmask;
233 if (!MSDOSFSEOF(pmp, cn)) {
237 *bnp = cntobn(pmp, cn);
240 fc_setcache(dep, FC_LASTMAP, i, cn);
249 /* update last file cluster entry in the FAT cache */
250 fc_setcache(dep, FC_LASTFC, i - 1, prevcn);
255 * Find the closest entry in the FAT cache to the cluster we are looking
259 fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp)
263 struct fatcache *closest = NULL;
265 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup");
267 for (i = 0; i < FC_SIZE; i++) {
268 cn = dep->de_fc[i].fc_frcn;
269 if (cn != FCE_EMPTY && cn <= findcn) {
270 if (closest == NULL || cn > closest->fc_frcn)
271 closest = &dep->de_fc[i];
275 *frcnp = closest->fc_frcn;
276 *fsrcnp = closest->fc_fsrcn;
281 * Purge the FAT cache in denode dep of all entries relating to file
282 * relative cluster frcn and beyond.
285 fc_purge(struct denode *dep, u_int frcn)
288 struct fatcache *fcp;
290 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge");
293 for (i = 0; i < FC_SIZE; i++, fcp++) {
294 if (fcp->fc_frcn >= frcn)
295 fcp->fc_frcn = FCE_EMPTY;
301 * If mirroring the FAT, update all copies, with the first copy as last.
302 * Else update only the current FAT (ignoring the others).
304 * pmp - msdosfsmount structure for filesystem to update
305 * bp - addr of modified FAT block
306 * fatbn - block number relative to begin of filesystem of the modified FAT block.
309 updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn)
315 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn);
318 if (pmp->pm_flags & MSDOSFS_FATMIRROR) {
320 * Now copy the block(s) of the modified FAT to the other copies of
321 * the FAT and write them out. This is faster than reading in the
322 * other FATs and then writing them back out. This could tie up
323 * the FAT for quite a while. Preventing others from accessing it.
324 * To prevent us from going after the FAT quite so much we use
325 * delayed writes, unless they specified "synchronous" when the
326 * filesystem was mounted. If synch is asked for then use
327 * bwrite()'s and really slow things down.
329 if (fatbn != pmp->pm_fatblk || FAT12(pmp))
335 for (i = 1; i < pmp->pm_FATs; i++) {
336 fatbn += pmp->pm_FATsecs;
337 /* getblk() never fails */
338 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount,
340 memcpy(bpn->b_data, bp->b_data, bp->b_bcount);
341 /* Force the clean bit on in the other copies. */
343 ((uint8_t *)bpn->b_data)[3] |= 0x80;
344 else if (cleanfat == 32)
345 ((uint8_t *)bpn->b_data)[7] |= 0x08;
346 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS)
354 * Write out the first (or current) FAT last.
356 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS)
363 * Updating entries in 12 bit FATs is a pain in the butt.
365 * The following picture shows where nibbles go when moving from a 12 bit
366 * cluster number into the appropriate bytes in the FAT.
368 * byte m byte m+1 byte m+2
369 * +----+----+ +----+----+ +----+----+
370 * | 0 1 | | 2 3 | | 4 5 | FAT bytes
371 * +----+----+ +----+----+ +----+----+
373 * +----+----+----+ +----+----+----+
374 * | 3 0 1 | | 4 5 2 |
375 * +----+----+----+ +----+----+----+
376 * cluster n cluster n+1
378 * Where n is even. m = n + (n >> 2)
382 usemap_alloc(struct msdosfsmount *pmp, u_long cn)
385 MSDOSFS_ASSERT_MP_LOCKED(pmp);
387 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn,
388 pmp->pm_maxcluster));
389 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0,
390 ("usemap_alloc on ro msdosfs mount"));
391 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS)))
392 == 0, ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS,
393 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS]));
394 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS);
395 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little"));
396 pmp->pm_freeclustercount--;
397 pmp->pm_flags |= MSDOSFS_FSIMOD;
401 usemap_free(struct msdosfsmount *pmp, u_long cn)
404 MSDOSFS_ASSERT_MP_LOCKED(pmp);
406 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn,
407 pmp->pm_maxcluster));
408 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0,
409 ("usemap_free on ro msdosfs mount"));
410 pmp->pm_freeclustercount++;
411 pmp->pm_flags |= MSDOSFS_FSIMOD;
412 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS)))
413 != 0, ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS,
414 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS]));
415 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1U << (cn % N_INUSEBITS));
419 clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp)
424 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE);
428 * If the cluster was successfully marked free, then update
429 * the count of free clusters, and turn off the "allocated"
430 * bit in the "in use" cluster bit map.
432 MSDOSFS_LOCK_MP(pmp);
433 usemap_free(pmp, cluster);
434 MSDOSFS_UNLOCK_MP(pmp);
441 * Get or Set or 'Get and Set' the cluster'th entry in the FAT.
443 * function - whether to get or set a FAT entry
444 * pmp - address of the msdosfsmount structure for the filesystem
445 * whose FAT is to be manipulated.
446 * cn - which cluster is of interest
447 * oldcontents - address of a word that is to receive the contents of the
448 * cluster'th entry if this is a get function
449 * newcontents - the new value to be written into the cluster'th element of
450 * the FAT if this is a set function.
452 * This function can also be used to free a cluster by setting the FAT entry
453 * for a cluster to 0.
455 * All copies of the FAT are updated if this is a set function. NOTE: If
456 * fatentry() marks a cluster as free it does not update the inusemap in
457 * the msdosfsmount structure. This is left to the caller.
460 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents,
465 u_long bn, bo, bsize, byteoffset;
469 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n",
470 function, pmp, cn, oldcontents, newcontents);
475 * Be sure they asked us to do something.
477 if ((function & (FAT_SET | FAT_GET)) == 0) {
479 printf("fatentry(): function code doesn't specify get or set\n");
485 * If they asked us to return a cluster number but didn't tell us
486 * where to put it, give them an error.
488 if ((function & FAT_GET) && oldcontents == NULL) {
490 printf("fatentry(): get function with no place to put result\n");
497 * Be sure the requested cluster is in the filesystem.
499 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster)
502 byteoffset = FATOFS(pmp, cn);
503 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
504 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
510 if (function & FAT_GET) {
512 readcn = getulong(&bp->b_data[bo]);
514 readcn = getushort(&bp->b_data[bo]);
515 if (FAT12(pmp) & (cn & 1))
517 readcn &= pmp->pm_fatmask;
518 /* map reserved FAT entries to same values for all FATs */
519 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
520 readcn |= ~pmp->pm_fatmask;
521 *oldcontents = readcn;
523 if (function & FAT_SET) {
524 switch (pmp->pm_fatmask) {
526 readcn = getushort(&bp->b_data[bo]);
529 readcn |= newcontents << 4;
532 readcn |= newcontents & 0xfff;
534 putushort(&bp->b_data[bo], readcn);
537 putushort(&bp->b_data[bo], newcontents);
541 * According to spec we have to retain the
542 * high order bits of the FAT entry.
544 readcn = getulong(&bp->b_data[bo]);
545 readcn &= ~FAT32_MASK;
546 readcn |= newcontents & FAT32_MASK;
547 putulong(&bp->b_data[bo], readcn);
550 updatefats(pmp, bp, bn);
560 * Update a contiguous cluster chain
563 * start - first cluster of chain
564 * count - number of clusters in chain
565 * fillwith - what to write into FAT entry of last cluster
568 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith)
571 u_long bn, bo, bsize, byteoffset, readcn, newc;
575 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n",
576 pmp, start, count, fillwith);
579 * Be sure the clusters are in the filesystem.
581 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster)
585 byteoffset = FATOFS(pmp, start);
586 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
587 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
594 newc = --count > 0 ? start : fillwith;
595 switch (pmp->pm_fatmask) {
597 readcn = getushort(&bp->b_data[bo]);
600 readcn |= newc & 0xfff;
605 putushort(&bp->b_data[bo], readcn);
611 putushort(&bp->b_data[bo], newc);
615 readcn = getulong(&bp->b_data[bo]);
616 readcn &= ~pmp->pm_fatmask;
617 readcn |= newc & pmp->pm_fatmask;
618 putulong(&bp->b_data[bo], readcn);
625 updatefats(pmp, bp, bn);
632 * Check the length of a free cluster chain starting at start.
635 * start - start of chain
636 * count - maximum interesting length
639 chainlength(struct msdosfsmount *pmp, u_long start, u_long count)
645 MSDOSFS_ASSERT_MP_LOCKED(pmp);
647 if (start > pmp->pm_maxcluster)
649 max_idx = pmp->pm_maxcluster / N_INUSEBITS;
650 idx = start / N_INUSEBITS;
651 start %= N_INUSEBITS;
652 map = pmp->pm_inusemap[idx];
653 map &= ~((1 << start) - 1);
655 len = ffs(map) - 1 - start;
656 len = MIN(len, count);
657 if (start + len > pmp->pm_maxcluster)
658 len = pmp->pm_maxcluster - start + 1;
661 len = N_INUSEBITS - start;
664 if (start + len > pmp->pm_maxcluster)
665 len = pmp->pm_maxcluster - start + 1;
668 while (++idx <= max_idx) {
671 map = pmp->pm_inusemap[idx];
678 len = MIN(len, count);
679 if (start + len > pmp->pm_maxcluster)
680 len = pmp->pm_maxcluster - start + 1;
685 * Allocate contigous free clusters.
688 * start - start of cluster chain.
689 * count - number of clusters to allocate.
690 * fillwith - put this value into the FAT entry for the
691 * last allocated cluster.
692 * retcluster - put the first allocated cluster's number here.
693 * got - how many clusters were actually allocated.
696 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count,
697 u_long fillwith, u_long *retcluster, u_long *got)
702 MSDOSFS_ASSERT_MP_LOCKED(pmp);
703 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0,
704 ("chainalloc on ro msdosfs mount"));
706 for (cl = start, n = count; n-- > 0;)
707 usemap_alloc(pmp, cl++);
708 pmp->pm_nxtfree = start + count;
709 if (pmp->pm_nxtfree > pmp->pm_maxcluster)
710 pmp->pm_nxtfree = CLUST_FIRST;
711 pmp->pm_flags |= MSDOSFS_FSIMOD;
712 error = fatchain(pmp, start, count, fillwith);
714 for (cl = start, n = count; n-- > 0;)
715 usemap_free(pmp, cl++);
719 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n",
730 * Allocate contiguous free clusters.
733 * start - preferred start of cluster chain.
734 * count - number of clusters requested.
735 * fillwith - put this value into the FAT entry for the
736 * last allocated cluster.
737 * retcluster - put the first allocated cluster's number here.
738 * got - how many clusters were actually allocated.
741 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count,
742 u_long fillwith, u_long *retcluster, u_long *got)
746 MSDOSFS_LOCK_MP(pmp);
747 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got);
748 MSDOSFS_UNLOCK_MP(pmp);
753 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count,
754 u_long fillwith, u_long *retcluster, u_long *got)
757 u_long len, newst, foundl, cn, l;
758 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */
761 MSDOSFS_ASSERT_MP_LOCKED(pmp);
764 printf("clusteralloc(): find %lu clusters\n", count);
767 if ((len = chainlength(pmp, start, count)) >= count)
768 return (chainalloc(pmp, start, count, fillwith, retcluster, got));
772 newst = pmp->pm_nxtfree;
775 for (cn = newst; cn <= pmp->pm_maxcluster;) {
776 idx = cn / N_INUSEBITS;
777 map = pmp->pm_inusemap[idx];
778 map |= (1U << (cn % N_INUSEBITS)) - 1;
779 if (map != FULL_RUN) {
780 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1;
781 if ((l = chainlength(pmp, cn, count)) >= count)
782 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
790 cn += N_INUSEBITS - cn % N_INUSEBITS;
792 for (cn = 0; cn < newst;) {
793 idx = cn / N_INUSEBITS;
794 map = pmp->pm_inusemap[idx];
795 map |= (1U << (cn % N_INUSEBITS)) - 1;
796 if (map != FULL_RUN) {
797 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1;
798 if ((l = chainlength(pmp, cn, count)) >= count)
799 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
807 cn += N_INUSEBITS - cn % N_INUSEBITS;
814 return (chainalloc(pmp, start, len, fillwith, retcluster, got));
816 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got));
821 * Free a chain of clusters.
823 * pmp - address of the msdosfs mount structure for the filesystem
824 * containing the cluster chain to be freed.
825 * startcluster - number of the 1st cluster in the chain of clusters to be
829 freeclusterchain(struct msdosfsmount *pmp, u_long cluster)
832 struct buf *bp = NULL;
833 u_long bn, bo, bsize, byteoffset;
834 u_long readcn, lbn = -1;
836 MSDOSFS_LOCK_MP(pmp);
837 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) {
838 byteoffset = FATOFS(pmp, cluster);
839 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
842 updatefats(pmp, bp, lbn);
843 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
846 MSDOSFS_UNLOCK_MP(pmp);
851 usemap_free(pmp, cluster);
852 switch (pmp->pm_fatmask) {
854 readcn = getushort(&bp->b_data[bo]);
856 cluster = readcn >> 4;
858 readcn |= MSDOSFSFREE << 4;
862 readcn |= MSDOSFSFREE & 0xfff;
864 putushort(&bp->b_data[bo], readcn);
867 cluster = getushort(&bp->b_data[bo]);
868 putushort(&bp->b_data[bo], MSDOSFSFREE);
871 cluster = getulong(&bp->b_data[bo]);
872 putulong(&bp->b_data[bo],
873 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK));
876 cluster &= pmp->pm_fatmask;
877 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD)
878 cluster |= pmp->pm_fatmask;
881 updatefats(pmp, bp, bn);
882 MSDOSFS_UNLOCK_MP(pmp);
887 * Read in FAT blocks looking for free clusters. For every free cluster
888 * found turn off its corresponding bit in the pm_inusemap.
891 fillinusemap(struct msdosfsmount *pmp)
894 u_long bn, bo, bsize, byteoffset, cn, readcn;
897 MSDOSFS_ASSERT_MP_LOCKED(pmp);
901 * Mark all clusters in use, we mark the free ones in the FAT scan
904 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++)
905 pmp->pm_inusemap[cn] = FULL_RUN;
908 * Figure how many free clusters are in the filesystem by ripping
909 * through the FAT counting the number of entries whose content is
910 * zero. These represent free clusters.
912 pmp->pm_freeclustercount = 0;
913 for (cn = 0; cn <= pmp->pm_maxcluster; cn++) {
914 byteoffset = FATOFS(pmp, cn);
915 bo = byteoffset % pmp->pm_fatblocksize;
917 /* Read new FAT block */
920 fatblock(pmp, byteoffset, &bn, &bsize, NULL);
921 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
926 readcn = getulong(&bp->b_data[bo]);
928 readcn = getushort(&bp->b_data[bo]);
929 if (FAT12(pmp) && (cn & 1))
931 readcn &= pmp->pm_fatmask;
934 * Check if the FAT ID matches the BPB's media descriptor and
935 * all other bits are set to 1.
937 if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) |
938 pmp->pm_bpb.bpbMedia)) {
940 printf("mountmsdosfs(): Media descriptor in BPB"
941 "does not match FAT ID\n");
945 } else if (readcn == CLUST_FREE)
946 usemap_free(pmp, cn);
951 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster +
952 N_INUSEBITS) / N_INUSEBITS; cn++)
953 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS);
959 * Allocate a new cluster and chain it onto the end of the file.
961 * dep - the file to extend
962 * count - number of clusters to allocate
963 * bpp - where to return the address of the buf header for the first new
965 * ncp - where to put cluster number of the first newly allocated cluster
966 * If this pointer is 0, do not return the cluster number.
969 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of
970 * the de_flag field of the denode and it does not change the de_FileSize
971 * field. This is left for the caller to do.
974 extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp,
980 struct msdosfsmount *pmp = dep->de_pmp;
985 * Don't try to extend the root directory
987 if (dep->de_StartCluster == MSDOSFSROOT
988 && (dep->de_Attributes & ATTR_DIRECTORY)) {
990 printf("extendfile(): attempt to extend root directory\n");
996 * If the "file's last cluster" cache entry is empty, and the file
997 * is not empty, then fill the cache entry by calling pcbmap().
999 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY &&
1000 dep->de_StartCluster != 0) {
1001 error = pcbmap(dep, 0xffff, 0, &cn, 0);
1002 /* we expect it to return E2BIG */
1007 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn =
1008 dep->de_fc[FC_LASTFC].fc_frcn;
1009 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn =
1010 dep->de_fc[FC_LASTFC].fc_fsrcn;
1013 * Allocate a new cluster chain and cat onto the end of the
1014 * file. If the file is empty we make de_StartCluster point
1015 * to the new block. Note that de_StartCluster being 0 is
1016 * sufficient to be sure the file is empty since we exclude
1017 * attempts to extend the root directory above, and the root
1018 * dir is the only file with a startcluster of 0 that has
1019 * blocks allocated (sort of).
1021 if (dep->de_StartCluster == 0)
1024 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1;
1025 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got);
1032 * Give them the filesystem relative cluster number if they want
1040 if (dep->de_StartCluster == 0) {
1041 dep->de_StartCluster = cn;
1044 error = fatentry(FAT_SET, pmp,
1045 dep->de_fc[FC_LASTFC].fc_fsrcn,
1048 clusterfree(pmp, cn, NULL);
1051 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1;
1055 * Update the "last cluster of the file" entry in the
1056 * denode's FAT cache.
1058 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1);
1060 if (flags & DE_CLEAR) {
1063 * Get the buf header for the new block of the file.
1065 if (dep->de_Attributes & ATTR_DIRECTORY)
1066 bp = getblk(pmp->pm_devvp,
1068 pmp->pm_bpcluster, 0, 0, 0);
1070 bp = getblk(DETOV(dep),
1072 pmp->pm_bpcluster, 0, 0, 0);
1074 * Do the bmap now, as in msdosfs_write
1080 if (bp->b_blkno == -1)
1081 panic("extendfile: pcbmap");
1083 bp->b_blkno = blkno;
1099 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by
1100 * manipulating the upper bit of the FAT entry for cluster 1. Note that
1101 * this bit is not defined for FAT12 volumes, which are always assumed to
1104 * The fatentry() routine only works on cluster numbers that a file could
1105 * occupy, so it won't manipulate the entry for cluster 1. So we have to do
1106 * it here. The code was stolen from fatentry() and tailored for cluster 1.
1109 * pmp The MS-DOS volume to mark
1110 * dirty Non-zero if the volume should be marked dirty; zero if it
1111 * should be marked clean
1115 * EROFS Volume is read-only
1116 * ? (other errors from called routines)
1119 markvoldirty(struct msdosfsmount *pmp, int dirty)
1122 u_long bn, bo, bsize, byteoffset, fatval;
1126 * FAT12 does not support a "clean" bit, so don't do anything for
1132 /* Can't change the bit on a read-only filesystem. */
1133 if (pmp->pm_flags & MSDOSFSMNT_RONLY)
1137 * Fetch the block containing the FAT entry. It is given by the
1140 byteoffset = FATOFS(pmp, 1);
1141 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
1142 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
1149 * Get the current value of the FAT entry and set/clear the relevant
1150 * bit. Dirty means clear the "clean" bit; clean means set the
1154 /* FAT32 uses bit 27. */
1155 fatval = getulong(&bp->b_data[bo]);
1157 fatval &= 0xF7FFFFFF;
1159 fatval |= 0x08000000;
1160 putulong(&bp->b_data[bo], fatval);
1162 /* Must be FAT16; use bit 15. */
1163 fatval = getushort(&bp->b_data[bo]);
1168 putushort(&bp->b_data[bo], fatval);
1171 /* Write out the modified FAT block synchronously. */
1172 return (bwrite(bp));