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_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS)))
403 == 0, ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS,
404 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS]));
405 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS);
406 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little"));
407 pmp->pm_freeclustercount--;
408 pmp->pm_flags |= MSDOSFS_FSIMOD;
413 struct msdosfsmount *pmp;
417 MSDOSFS_ASSERT_MP_LOCKED(pmp);
418 pmp->pm_freeclustercount++;
419 pmp->pm_flags |= MSDOSFS_FSIMOD;
420 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS)))
421 != 0, ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS,
422 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS]));
423 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS));
427 clusterfree(pmp, cluster, oldcnp)
428 struct msdosfsmount *pmp;
435 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE);
439 * If the cluster was successfully marked free, then update
440 * the count of free clusters, and turn off the "allocated"
441 * bit in the "in use" cluster bit map.
443 MSDOSFS_LOCK_MP(pmp);
444 usemap_free(pmp, cluster);
445 MSDOSFS_UNLOCK_MP(pmp);
452 * Get or Set or 'Get and Set' the cluster'th entry in the fat.
454 * function - whether to get or set a fat entry
455 * pmp - address of the msdosfsmount structure for the filesystem
456 * whose fat is to be manipulated.
457 * cn - which cluster is of interest
458 * oldcontents - address of a word that is to receive the contents of the
459 * cluster'th entry if this is a get function
460 * newcontents - the new value to be written into the cluster'th element of
461 * the fat if this is a set function.
463 * This function can also be used to free a cluster by setting the fat entry
464 * for a cluster to 0.
466 * All copies of the fat are updated if this is a set function. NOTE: If
467 * fatentry() marks a cluster as free it does not update the inusemap in
468 * the msdosfsmount structure. This is left to the caller.
471 fatentry(function, pmp, cn, oldcontents, newcontents)
473 struct msdosfsmount *pmp;
480 u_long bn, bo, bsize, byteoffset;
484 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n",
485 function, pmp, cn, oldcontents, newcontents);
490 * Be sure they asked us to do something.
492 if ((function & (FAT_SET | FAT_GET)) == 0) {
494 printf("fatentry(): function code doesn't specify get or set\n");
500 * If they asked us to return a cluster number but didn't tell us
501 * where to put it, give them an error.
503 if ((function & FAT_GET) && oldcontents == NULL) {
505 printf("fatentry(): get function with no place to put result\n");
512 * Be sure the requested cluster is in the filesystem.
514 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster)
517 byteoffset = FATOFS(pmp, cn);
518 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
519 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
525 if (function & FAT_GET) {
527 readcn = getulong(&bp->b_data[bo]);
529 readcn = getushort(&bp->b_data[bo]);
530 if (FAT12(pmp) & (cn & 1))
532 readcn &= pmp->pm_fatmask;
533 /* map reserved fat entries to same values for all fats */
534 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
535 readcn |= ~pmp->pm_fatmask;
536 *oldcontents = readcn;
538 if (function & FAT_SET) {
539 switch (pmp->pm_fatmask) {
541 readcn = getushort(&bp->b_data[bo]);
544 readcn |= newcontents << 4;
547 readcn |= newcontents & 0xfff;
549 putushort(&bp->b_data[bo], readcn);
552 putushort(&bp->b_data[bo], newcontents);
556 * According to spec we have to retain the
557 * high order bits of the fat entry.
559 readcn = getulong(&bp->b_data[bo]);
560 readcn &= ~FAT32_MASK;
561 readcn |= newcontents & FAT32_MASK;
562 putulong(&bp->b_data[bo], readcn);
565 updatefats(pmp, bp, bn);
575 * Update a contiguous cluster chain
578 * start - first cluster of chain
579 * count - number of clusters in chain
580 * fillwith - what to write into fat entry of last cluster
583 fatchain(pmp, start, count, fillwith)
584 struct msdosfsmount *pmp;
590 u_long bn, bo, bsize, byteoffset, readcn, newc;
594 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n",
595 pmp, start, count, fillwith);
598 * Be sure the clusters are in the filesystem.
600 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster)
604 byteoffset = FATOFS(pmp, start);
605 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
606 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
613 newc = --count > 0 ? start : fillwith;
614 switch (pmp->pm_fatmask) {
616 readcn = getushort(&bp->b_data[bo]);
619 readcn |= newc & 0xfff;
624 putushort(&bp->b_data[bo], readcn);
630 putushort(&bp->b_data[bo], newc);
634 readcn = getulong(&bp->b_data[bo]);
635 readcn &= ~pmp->pm_fatmask;
636 readcn |= newc & pmp->pm_fatmask;
637 putulong(&bp->b_data[bo], readcn);
644 updatefats(pmp, bp, bn);
651 * Check the length of a free cluster chain starting at start.
654 * start - start of chain
655 * count - maximum interesting length
658 chainlength(pmp, start, count)
659 struct msdosfsmount *pmp;
667 MSDOSFS_ASSERT_MP_LOCKED(pmp);
669 max_idx = pmp->pm_maxcluster / N_INUSEBITS;
670 idx = start / N_INUSEBITS;
671 start %= N_INUSEBITS;
672 map = pmp->pm_inusemap[idx];
673 map &= ~((1 << start) - 1);
675 len = ffs(map) - 1 - start;
676 return (len > count ? count : len);
678 len = N_INUSEBITS - start;
681 while (++idx <= max_idx) {
684 map = pmp->pm_inusemap[idx];
691 return (len > count ? count : len);
695 * Allocate contigous free clusters.
698 * start - start of cluster chain.
699 * count - number of clusters to allocate.
700 * fillwith - put this value into the fat entry for the
701 * last allocated cluster.
702 * retcluster - put the first allocated cluster's number here.
703 * got - how many clusters were actually allocated.
706 chainalloc(pmp, start, count, fillwith, retcluster, got)
707 struct msdosfsmount *pmp;
717 MSDOSFS_ASSERT_MP_LOCKED(pmp);
719 for (cl = start, n = count; n-- > 0;)
720 usemap_alloc(pmp, cl++);
721 pmp->pm_nxtfree = start + count;
722 if (pmp->pm_nxtfree > pmp->pm_maxcluster)
723 pmp->pm_nxtfree = CLUST_FIRST;
724 pmp->pm_flags |= MSDOSFS_FSIMOD;
725 error = fatchain(pmp, start, count, fillwith);
729 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n",
740 * Allocate contiguous free clusters.
743 * start - preferred start of cluster chain.
744 * count - number of clusters requested.
745 * fillwith - put this value into the fat entry for the
746 * last allocated cluster.
747 * retcluster - put the first allocated cluster's number here.
748 * got - how many clusters were actually allocated.
751 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count,
752 u_long fillwith, u_long *retcluster, u_long *got)
756 MSDOSFS_LOCK_MP(pmp);
757 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got);
758 MSDOSFS_UNLOCK_MP(pmp);
763 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count,
764 u_long fillwith, u_long *retcluster, u_long *got)
767 u_long len, newst, foundl, cn, l;
768 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */
771 MSDOSFS_ASSERT_MP_LOCKED(pmp);
774 printf("clusteralloc(): find %lu clusters\n", count);
777 if ((len = chainlength(pmp, start, count)) >= count)
778 return (chainalloc(pmp, start, count, fillwith, retcluster, got));
782 newst = pmp->pm_nxtfree;
785 for (cn = newst; cn <= pmp->pm_maxcluster;) {
786 idx = cn / N_INUSEBITS;
787 map = pmp->pm_inusemap[idx];
788 map |= (1 << (cn % N_INUSEBITS)) - 1;
789 if (map != (u_int)-1) {
790 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
791 if ((l = chainlength(pmp, cn, count)) >= count)
792 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
800 cn += N_INUSEBITS - cn % N_INUSEBITS;
802 for (cn = 0; cn < newst;) {
803 idx = cn / N_INUSEBITS;
804 map = pmp->pm_inusemap[idx];
805 map |= (1 << (cn % N_INUSEBITS)) - 1;
806 if (map != (u_int)-1) {
807 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1;
808 if ((l = chainlength(pmp, cn, count)) >= count)
809 return (chainalloc(pmp, cn, count, fillwith, retcluster, got));
817 cn += N_INUSEBITS - cn % N_INUSEBITS;
824 return (chainalloc(pmp, start, len, fillwith, retcluster, got));
826 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got));
831 * Free a chain of clusters.
833 * pmp - address of the msdosfs mount structure for the filesystem
834 * containing the cluster chain to be freed.
835 * startcluster - number of the 1st cluster in the chain of clusters to be
839 freeclusterchain(pmp, cluster)
840 struct msdosfsmount *pmp;
844 struct buf *bp = NULL;
845 u_long bn, bo, bsize, byteoffset;
846 u_long readcn, lbn = -1;
848 MSDOSFS_LOCK_MP(pmp);
849 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) {
850 byteoffset = FATOFS(pmp, cluster);
851 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
854 updatefats(pmp, bp, lbn);
855 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
858 MSDOSFS_UNLOCK_MP(pmp);
863 usemap_free(pmp, cluster);
864 switch (pmp->pm_fatmask) {
866 readcn = getushort(&bp->b_data[bo]);
868 cluster = readcn >> 4;
870 readcn |= MSDOSFSFREE << 4;
874 readcn |= MSDOSFSFREE & 0xfff;
876 putushort(&bp->b_data[bo], readcn);
879 cluster = getushort(&bp->b_data[bo]);
880 putushort(&bp->b_data[bo], MSDOSFSFREE);
883 cluster = getulong(&bp->b_data[bo]);
884 putulong(&bp->b_data[bo],
885 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK));
888 cluster &= pmp->pm_fatmask;
889 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD)
890 cluster |= pmp->pm_fatmask;
893 updatefats(pmp, bp, bn);
894 MSDOSFS_UNLOCK_MP(pmp);
899 * Read in fat blocks looking for free clusters. For every free cluster
900 * found turn off its corresponding bit in the pm_inusemap.
904 struct msdosfsmount *pmp;
906 struct buf *bp = NULL;
909 u_long bn, bo, bsize, byteoffset;
911 MSDOSFS_ASSERT_MP_LOCKED(pmp);
914 * Mark all clusters in use, we mark the free ones in the fat scan
917 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++)
918 pmp->pm_inusemap[cn] = (u_int)-1;
921 * Figure how many free clusters are in the filesystem by ripping
922 * through the fat counting the number of entries whose content is
923 * zero. These represent free clusters.
925 pmp->pm_freeclustercount = 0;
926 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) {
927 byteoffset = FATOFS(pmp, cn);
928 bo = byteoffset % pmp->pm_fatblocksize;
930 /* Read new FAT block */
933 fatblock(pmp, byteoffset, &bn, &bsize, NULL);
934 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
941 readcn = getulong(&bp->b_data[bo]);
943 readcn = getushort(&bp->b_data[bo]);
944 if (FAT12(pmp) && (cn & 1))
946 readcn &= pmp->pm_fatmask;
949 usemap_free(pmp, cn);
957 * Allocate a new cluster and chain it onto the end of the file.
959 * dep - the file to extend
960 * count - number of clusters to allocate
961 * bpp - where to return the address of the buf header for the first new
963 * ncp - where to put cluster number of the first newly allocated cluster
964 * If this pointer is 0, do not return the cluster number.
967 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of
968 * the de_flag field of the denode and it does not change the de_FileSize
969 * field. This is left for the caller to do.
972 extendfile(dep, count, bpp, ncp, flags)
982 struct msdosfsmount *pmp = dep->de_pmp;
987 * Don't try to extend the root directory
989 if (dep->de_StartCluster == MSDOSFSROOT
990 && (dep->de_Attributes & ATTR_DIRECTORY)) {
992 printf("extendfile(): attempt to extend root directory\n");
998 * If the "file's last cluster" cache entry is empty, and the file
999 * is not empty, then fill the cache entry by calling pcbmap().
1001 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY &&
1002 dep->de_StartCluster != 0) {
1003 error = pcbmap(dep, 0xffff, 0, &cn, 0);
1004 /* we expect it to return E2BIG */
1009 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn =
1010 dep->de_fc[FC_LASTFC].fc_frcn;
1011 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn =
1012 dep->de_fc[FC_LASTFC].fc_fsrcn;
1015 * Allocate a new cluster chain and cat onto the end of the
1016 * file. * If the file is empty we make de_StartCluster point
1017 * to the new block. Note that de_StartCluster being 0 is
1018 * sufficient to be sure the file is empty since we exclude
1019 * attempts to extend the root directory above, and the root
1020 * dir is the only file with a startcluster of 0 that has
1021 * blocks allocated (sort of).
1023 if (dep->de_StartCluster == 0)
1026 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1;
1027 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got);
1034 * Give them the filesystem relative cluster number if they want
1042 if (dep->de_StartCluster == 0) {
1043 dep->de_StartCluster = cn;
1046 error = fatentry(FAT_SET, pmp,
1047 dep->de_fc[FC_LASTFC].fc_fsrcn,
1050 clusterfree(pmp, cn, NULL);
1053 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1;
1057 * Update the "last cluster of the file" entry in the denode's fat
1060 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1);
1062 if (flags & DE_CLEAR) {
1065 * Get the buf header for the new block of the file.
1067 if (dep->de_Attributes & ATTR_DIRECTORY)
1068 bp = getblk(pmp->pm_devvp,
1070 pmp->pm_bpcluster, 0, 0, 0);
1072 bp = getblk(DETOV(dep),
1074 pmp->pm_bpcluster, 0, 0, 0);
1076 * Do the bmap now, as in msdosfs_write
1082 if (bp->b_blkno == -1)
1083 panic("extendfile: pcbmap");
1085 bp->b_blkno = blkno;
1101 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by
1102 * manipulating the upper bit of the FAT entry for cluster 1. Note that
1103 * this bit is not defined for FAT12 volumes, which are always assumed to
1106 * The fatentry() routine only works on cluster numbers that a file could
1107 * occupy, so it won't manipulate the entry for cluster 1. So we have to do
1108 * it here. The code was stolen from fatentry() and tailored for cluster 1.
1111 * pmp The MS-DOS volume to mark
1112 * dirty Non-zero if the volume should be marked dirty; zero if it
1113 * should be marked clean
1117 * EROFS Volume is read-only
1118 * ? (other errors from called routines)
1121 markvoldirty(struct msdosfsmount *pmp, int dirty)
1124 u_long bn, bo, bsize, byteoffset, fatval;
1128 * FAT12 does not support a "clean" bit, so don't do anything for
1134 /* Can't change the bit on a read-only filesystem. */
1135 if (pmp->pm_flags & MSDOSFSMNT_RONLY)
1139 * Fetch the block containing the FAT entry. It is given by the
1142 byteoffset = FATOFS(pmp, 1);
1143 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
1144 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp);
1151 * Get the current value of the FAT entry and set/clear the relevant
1152 * bit. Dirty means clear the "clean" bit; clean means set the
1156 /* FAT32 uses bit 27. */
1157 fatval = getulong(&bp->b_data[bo]);
1159 fatval &= 0xF7FFFFFF;
1161 fatval |= 0x08000000;
1162 putulong(&bp->b_data[bo], fatval);
1164 /* Must be FAT16; use bit 15. */
1165 fatval = getushort(&bp->b_data[bo]);
1170 putushort(&bp->b_data[bo], fatval);
1173 /* Write out the modified FAT block synchronously. */
1174 return (bwrite(bp));