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>
61 #include <vfs/msdosfs/bpb.h>
62 #include <vfs/msdosfs/direntry.h>
63 #include <vfs/msdosfs/denode.h>
64 #include <vfs/msdosfs/fat.h>
65 #include <vfs/msdosfs/msdosfsmount.h>
67 #define FULL_RUN ((u_int)0xffffffff)
69 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp,
71 static int clusteralloc1(struct msdosfsmount *pmp, u_long start,
72 u_long count, u_long fillwith, u_long *retcluster,
76 * Given a byte offset `ofs` within FAT, return block number in backing device,
77 * block size, and byte offset within a block in FAT.
80 fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep,
85 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec;
86 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) * DEV_BSIZE;
87 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs;
94 *bop = ofs % pmp->pm_fatblocksize;
98 * Map the logical cluster number of a file into a physical disk sector
99 * that is filesystem relative.
101 * dep - address of denode representing the file of interest
102 * findcn - file relative cluster whose filesystem relative cluster number
103 * and/or block number are/is to be found
104 * bnp - address of where to place the filesystem relative block number.
105 * If this pointer is null then don't return this quantity.
106 * cnp - address of where to place the filesystem relative cluster number.
107 * If this pointer is null then don't return this quantity.
108 * sp - pointer to returned block size
110 * NOTE: Either bnp or cnp must be non-null.
111 * This function has one side effect. If the requested file relative cluster
112 * is beyond the end of file, then the actual number of clusters in the file
113 * is returned in *cnp. This is useful for determining how long a directory is.
114 * If cnp is null, nothing is returned.
117 pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp)
122 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */
126 struct buf *bp = NULL;
128 struct msdosfsmount *pmp = dep->de_pmp;
131 KASSERT(bnp != NULL || cnp != NULL || sp != NULL,
132 ("pcbmap: extra call"));
133 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap");
135 cn = dep->de_StartCluster;
137 * The "file" that makes up the root directory is contiguous,
138 * permanently allocated, of fixed size, and is not made up of
139 * clusters. If the cluster number is beyond the end of the root
140 * directory, then return the number of clusters in the file.
142 if (cn == MSDOSFSROOT) {
143 if (dep->de_Attributes & ATTR_DIRECTORY) {
144 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) {
147 pmp->pm_rootdirsize);
151 *bnp = pmp->pm_rootdirblk +
152 de_cn2bn(pmp, findcn);
156 *sp = min(pmp->pm_bpcluster,
157 dep->de_FileSize - de_cn2off(pmp, findcn));
159 } else { /* just an empty file */
167 * All other files do I/O in cluster sized blocks
170 *sp = pmp->pm_bpcluster;
173 * Rummage around in the FAT cache, maybe we can avoid tromping
174 * through every FAT entry for the file. And, keep track of how far
175 * off the cache was from where we wanted to be.
178 fc_lookup(dep, findcn, &i, &cn);
181 * Handle all other files or directories the normal way.
183 for (; i < findcn; i++) {
185 * Stop with all reserved clusters, not just with EOF.
187 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
189 byteoffset = FATOFS(pmp, cn);
190 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
194 error = bread(pmp->pm_devvp, de_bn2doff(pmp, bn),
209 cn = getulong(bp->b_data + bo);
211 cn = getushort(bp->b_data + bo);
212 if (FAT12(pmp) && (prevcn & 1))
214 cn &= pmp->pm_fatmask;
217 * Force the special cluster numbers
218 * to be the same for all cluster sizes
219 * to let the rest of msdosfs handle
220 * all cases the same.
222 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
223 cn |= ~pmp->pm_fatmask;
226 if (!MSDOSFSEOF(pmp, cn)) {
230 *bnp = cntobn(pmp, cn);
233 fc_setcache(dep, FC_LASTMAP, i, cn);
242 /* update last file cluster entry in the FAT cache */
243 fc_setcache(dep, FC_LASTFC, i - 1, prevcn);
248 * Find the closest entry in the FAT cache to the cluster we are looking
252 fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp)
256 struct fatcache *closest = NULL;
258 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup");
260 for (i = 0; i < FC_SIZE; i++) {
261 cn = dep->de_fc[i].fc_frcn;
262 if (cn != FCE_EMPTY && cn <= findcn) {
263 if (closest == NULL || cn > closest->fc_frcn)
264 closest = &dep->de_fc[i];
268 *frcnp = closest->fc_frcn;
269 *fsrcnp = closest->fc_fsrcn;
274 * Purge the FAT cache in denode dep of all entries relating to file
275 * relative cluster frcn and beyond.
278 fc_purge(struct denode *dep, u_int frcn)
281 struct fatcache *fcp;
283 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge");
286 for (i = 0; i < FC_SIZE; i++, fcp++) {
287 if (fcp->fc_frcn >= frcn)
288 fcp->fc_frcn = FCE_EMPTY;
294 * If mirroring the FAT, update all copies, with the first copy as last.
295 * Else update only the current FAT (ignoring the others).
297 * pmp - msdosfsmount structure for filesystem to update
298 * bp - addr of modified FAT block
299 * fatbn - block number relative to begin of filesystem of the modified FAT block.
302 updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn)
307 mprintf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn);
309 if (pmp->pm_flags & MSDOSFS_FATMIRROR) {
311 * Now copy the block(s) of the modified FAT to the other copies of
312 * the FAT and write them out. This is faster than reading in the
313 * other FATs and then writing them back out. This could tie up
314 * the FAT for quite a while. Preventing others from accessing it.
315 * To prevent us from going after the FAT quite so much we use
316 * delayed writes, unless they specified "synchronous" when the
317 * filesystem was mounted. If synch is asked for then use
318 * bwrite()'s and really slow things down.
320 if (fatbn != pmp->pm_fatblk || FAT12(pmp))
326 for (i = 1; i < pmp->pm_FATs; i++) {
327 fatbn += pmp->pm_FATsecs;
328 /* getblk() never fails */
329 bpn = getblk(pmp->pm_devvp, de_bn2doff(pmp, fatbn),
331 memcpy(bpn->b_data, bp->b_data, bp->b_bcount);
332 /* Force the clean bit on in the other copies. */
334 ((uint8_t *)bpn->b_data)[3] |= 0x80;
335 else if (cleanfat == 32)
336 ((uint8_t *)bpn->b_data)[7] |= 0x08;
337 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS)
345 * Write out the first (or current) FAT last.
347 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS)
354 * Updating entries in 12 bit FATs is a pain in the butt.
356 * The following picture shows where nibbles go when moving from a 12 bit
357 * cluster number into the appropriate bytes in the FAT.
359 * byte m byte m+1 byte m+2
360 * +----+----+ +----+----+ +----+----+
361 * | 0 1 | | 2 3 | | 4 5 | FAT bytes
362 * +----+----+ +----+----+ +----+----+
364 * +----+----+----+ +----+----+----+
365 * | 3 0 1 | | 4 5 2 |
366 * +----+----+----+ +----+----+----+
367 * cluster n cluster n+1
369 * Where n is even. m = n + (n >> 2)
373 usemap_alloc(struct msdosfsmount *pmp, u_long cn)
375 MSDOSFS_ASSERT_MP_LOCKED(pmp);
377 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn,
378 pmp->pm_maxcluster));
379 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0,
380 ("usemap_alloc on ro msdosfs mount"));
381 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] &
382 (1U << (cn % N_INUSEBITS))) == 0,
383 ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS,
384 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS]));
385 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS);
386 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little"));
387 pmp->pm_freeclustercount--;
388 pmp->pm_flags |= MSDOSFS_FSIMOD;
392 usemap_free(struct msdosfsmount *pmp, u_long cn)
394 MSDOSFS_ASSERT_MP_LOCKED(pmp);
396 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn,
397 pmp->pm_maxcluster));
398 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0,
399 ("usemap_free on ro msdosfs mount"));
400 if ((pmp->pm_inusemap[cn / N_INUSEBITS] &
401 (1U << (cn % N_INUSEBITS))) == 0) {
402 kprintf("%s: Freeing unused sector %ld %ld %x\n",
403 pmp->pm_mountp->mnt_stat.f_mntonname, cn, cn % N_INUSEBITS,
404 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS]);
407 pmp->pm_freeclustercount++;
408 pmp->pm_flags |= MSDOSFS_FSIMOD;
409 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1U << (cn % N_INUSEBITS));
414 clusterfree(struct msdosfsmount *pmp, u_long cluster)
419 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE);
423 * If the cluster was successfully marked free, then update
424 * the count of free clusters, and turn off the "allocated"
425 * bit in the "in use" cluster bit map.
427 MSDOSFS_LOCK_MP(pmp);
428 error = usemap_free(pmp, cluster);
429 MSDOSFS_UNLOCK_MP(pmp);
433 * Get or Set or 'Get and Set' the cluster'th entry in the FAT.
435 * function - whether to get or set a FAT entry
436 * pmp - address of the msdosfsmount structure for the filesystem
437 * whose FAT is to be manipulated.
438 * cn - which cluster is of interest
439 * oldcontents - address of a word that is to receive the contents of the
440 * cluster'th entry if this is a get function
441 * newcontents - the new value to be written into the cluster'th element of
442 * the FAT if this is a set function.
444 * This function can also be used to free a cluster by setting the FAT entry
445 * for a cluster to 0.
447 * All copies of the FAT are updated if this is a set function. NOTE: If
448 * fatentry() marks a cluster as free it does not update the inusemap in
449 * the msdosfsmount structure. This is left to the caller.
452 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents,
457 u_long bn, bo, bsize, byteoffset;
460 mprintf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n",
461 function, pmp, cn, oldcontents, newcontents);
465 * Be sure they asked us to do something.
467 if ((function & (FAT_SET | FAT_GET)) == 0) {
468 kprintf("fatentry(): function code doesn't specify get or set\n");
473 * If they asked us to return a cluster number but didn't tell us
474 * where to put it, give them an error.
476 if ((function & FAT_GET) && oldcontents == NULL) {
477 kprintf("fatentry(): get function with no place to put result\n");
483 * Be sure the requested cluster is in the filesystem.
485 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster)
488 byteoffset = FATOFS(pmp, cn);
489 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
490 error = bread(pmp->pm_devvp, de_bn2doff(pmp, bn), bsize, &bp);
496 if (function & FAT_GET) {
498 readcn = getulong(bp->b_data + bo);
500 readcn = getushort(bp->b_data + bo);
501 if (FAT12(pmp) & (cn & 1))
503 readcn &= pmp->pm_fatmask;
504 /* map reserved FAT entries to same values for all FATs */
505 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD)
506 readcn |= ~pmp->pm_fatmask;
507 *oldcontents = readcn;
509 if (function & FAT_SET) {
510 switch (pmp->pm_fatmask) {
512 readcn = getushort(bp->b_data + bo);
515 readcn |= newcontents << 4;
518 readcn |= newcontents & 0xfff;
520 putushort(bp->b_data + bo, readcn);
523 putushort(bp->b_data + bo, newcontents);
527 * According to spec we have to retain the
528 * high order bits of the FAT entry.
530 readcn = getulong(bp->b_data + bo);
531 readcn &= ~FAT32_MASK;
532 readcn |= newcontents & FAT32_MASK;
533 putulong(bp->b_data + bo, readcn);
536 updatefats(pmp, bp, bn);
546 * Update a contiguous cluster chain
549 * start - first cluster of chain
550 * count - number of clusters in chain
551 * fillwith - what to write into FAT entry of last cluster
554 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith)
557 u_long bn, bo, bsize, byteoffset, readcn, newc;
560 mprintf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n",
561 pmp, start, count, fillwith);
563 * Be sure the clusters are in the filesystem.
565 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster)
569 byteoffset = FATOFS(pmp, start);
570 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
571 error = bread(pmp->pm_devvp, de_bn2doff(pmp, bn), bsize, &bp);
577 start++; /* Callers must guarantee contiguous free
579 newc = --count > 0 ? start : fillwith;
580 switch (pmp->pm_fatmask) {
582 readcn = getushort(bp->b_data + bo);
585 readcn |= newc & 0xfff;
590 putushort(bp->b_data + bo, readcn);
596 putushort(bp->b_data + bo, newc);
600 readcn = getulong(bp->b_data + bo);
601 readcn &= ~pmp->pm_fatmask;
602 readcn |= newc & pmp->pm_fatmask;
603 putulong(bp->b_data + bo, readcn);
610 updatefats(pmp, bp, bn);
617 * Check the length of a free cluster chain starting at start.
620 * start - start of chain
621 * count - maximum interesting length
624 chainlength(struct msdosfsmount *pmp, u_long start, u_long count)
630 MSDOSFS_ASSERT_MP_LOCKED(pmp);
632 if (start > pmp->pm_maxcluster)
634 max_idx = pmp->pm_maxcluster / N_INUSEBITS;
635 idx = start / N_INUSEBITS;
636 start %= N_INUSEBITS;
637 map = pmp->pm_inusemap[idx];
638 map &= ~((1U << start) - 1);
640 len = ffs(map) - 1 - start;
641 len = MIN(len, count);
642 if (start + len > pmp->pm_maxcluster)
643 len = pmp->pm_maxcluster - start + 1;
646 len = N_INUSEBITS - start;
649 if (start + len > pmp->pm_maxcluster)
650 len = pmp->pm_maxcluster - start + 1;
653 while (++idx <= max_idx) {
656 map = pmp->pm_inusemap[idx];
663 len = MIN(len, count);
664 if (start + len > pmp->pm_maxcluster)
665 len = pmp->pm_maxcluster - start + 1;
670 * Allocate contigous free clusters.
673 * start - start of cluster chain.
674 * count - number of clusters to allocate.
675 * fillwith - put this value into the FAT entry for the
676 * last allocated cluster.
677 * retcluster - put the first allocated cluster's number here.
678 * got - how many clusters were actually allocated.
681 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count,
682 u_long fillwith, u_long *retcluster, u_long *got)
687 MSDOSFS_ASSERT_MP_LOCKED(pmp);
688 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0,
689 ("chainalloc on ro msdosfs mount"));
691 for (cl = start, n = count; n-- > 0;)
692 usemap_alloc(pmp, cl++);
694 pmp->pm_nxtfree = start + count;
695 if (pmp->pm_nxtfree > pmp->pm_maxcluster)
696 pmp->pm_nxtfree = CLUST_FIRST;
697 pmp->pm_flags |= MSDOSFS_FSIMOD;
699 error = fatchain(pmp, start, count, fillwith);
701 for (cl = start, n = count; n-- > 0;)
702 (void)usemap_free(pmp, cl++);
705 mprintf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n",
715 * Allocate contiguous free clusters.
718 * start - preferred start of cluster chain.
719 * count - number of clusters requested.
720 * fillwith - put this value into the FAT entry for the
721 * last allocated cluster.
722 * retcluster - put the first allocated cluster's number here.
723 * got - how many clusters were actually allocated.
726 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count,
727 u_long fillwith, u_long *retcluster, u_long *got)
731 MSDOSFS_LOCK_MP(pmp);
732 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got);
733 MSDOSFS_UNLOCK_MP(pmp);
738 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count,
739 u_long fillwith, u_long *retcluster, u_long *got)
742 u_long len, newst, foundl, cn, l;
743 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */
746 MSDOSFS_ASSERT_MP_LOCKED(pmp);
748 mprintf("clusteralloc(): find %lu clusters\n",count);
750 if ((len = chainlength(pmp, start, count)) >= count)
751 return (chainalloc(pmp, start, count, fillwith,
756 newst = pmp->pm_nxtfree;
759 for (cn = newst; cn <= pmp->pm_maxcluster;) {
760 idx = cn / N_INUSEBITS;
761 map = pmp->pm_inusemap[idx];
762 map |= (1U << (cn % N_INUSEBITS)) - 1;
763 if (map != FULL_RUN) {
764 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1;
765 if ((l = chainlength(pmp, cn, count)) >= count)
766 return (chainalloc(pmp, cn, count, fillwith,
775 cn += N_INUSEBITS - cn % N_INUSEBITS;
777 for (cn = 0; cn < newst;) {
778 idx = cn / N_INUSEBITS;
779 map = pmp->pm_inusemap[idx];
780 map |= (1U << (cn % N_INUSEBITS)) - 1;
781 if (map != FULL_RUN) {
782 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1;
783 if ((l = chainlength(pmp, cn, count)) >= count)
784 return (chainalloc(pmp, cn, count, fillwith,
793 cn += N_INUSEBITS - cn % N_INUSEBITS;
800 return (chainalloc(pmp, start, len, fillwith, retcluster, got));
802 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster,
807 * Free a chain of clusters.
809 * pmp - address of the msdosfs mount structure for the filesystem
810 * containing the cluster chain to be freed.
811 * startcluster - number of the 1st cluster in the chain of clusters to be
815 freeclusterchain(struct msdosfsmount *pmp, u_long cluster)
818 struct buf *bp = NULL;
819 u_long bn, bo, bsize, byteoffset;
820 u_long readcn, lbn = -1;
822 MSDOSFS_LOCK_MP(pmp);
823 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) {
824 byteoffset = FATOFS(pmp, cluster);
825 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
828 updatefats(pmp, bp, lbn);
829 error = bread(pmp->pm_devvp, de_bn2doff(pmp, bn),
833 MSDOSFS_UNLOCK_MP(pmp);
838 error = usemap_free(pmp, cluster);
840 updatefats(pmp, bp, lbn);
841 MSDOSFS_UNLOCK_MP(pmp);
844 switch (pmp->pm_fatmask) {
846 readcn = getushort(bp->b_data + bo);
848 cluster = readcn >> 4;
850 readcn |= MSDOSFSFREE << 4;
854 readcn |= MSDOSFSFREE & 0xfff;
856 putushort(bp->b_data + bo, readcn);
859 cluster = getushort(bp->b_data + bo);
860 putushort(bp->b_data + bo, MSDOSFSFREE);
863 cluster = getulong(bp->b_data + bo);
864 putulong(bp->b_data + bo,
865 (MSDOSFSFREE & FAT32_MASK) |
866 (cluster & ~FAT32_MASK));
869 cluster &= pmp->pm_fatmask;
870 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD)
871 cluster |= pmp->pm_fatmask;
874 updatefats(pmp, bp, bn);
875 MSDOSFS_UNLOCK_MP(pmp);
880 * Read in FAT blocks looking for free clusters. For every free cluster
881 * found turn off its corresponding bit in the pm_inusemap.
884 fillinusemap(struct msdosfsmount *pmp)
887 u_long bn, bo, bsize, byteoffset, cn, readcn;
890 MSDOSFS_ASSERT_MP_LOCKED(pmp);
894 * Mark all clusters in use, we mark the free ones in the FAT scan
897 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++)
898 pmp->pm_inusemap[cn] = FULL_RUN;
901 * Figure how many free clusters are in the filesystem by ripping
902 * through the FAT counting the number of entries whose content is
903 * zero. These represent free clusters.
905 pmp->pm_freeclustercount = 0;
906 for (cn = 0; cn <= pmp->pm_maxcluster; cn++) {
907 byteoffset = FATOFS(pmp, cn);
908 bo = byteoffset % pmp->pm_fatblocksize;
910 /* Read new FAT block */
913 fatblock(pmp, byteoffset, &bn, &bsize, NULL);
914 error = bread(pmp->pm_devvp, de_bn2doff(pmp, bn),
922 readcn = getulong(bp->b_data + bo);
924 readcn = getushort(bp->b_data + bo);
925 if (FAT12(pmp) && (cn & 1))
927 readcn &= pmp->pm_fatmask;
930 * Check if the FAT ID matches the BPB's media descriptor and
931 * all other bits are set to 1.
933 if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) |
934 pmp->pm_bpb.bpbMedia)) {
935 mprintf("fillinusemap(): Media descriptor in BPB "
936 "does not match FAT ID\n");
939 } else if (readcn == CLUST_FREE) {
940 error = usemap_free(pmp, cn);
950 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster +
951 N_INUSEBITS) / N_INUSEBITS; cn++)
952 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS);
958 * Allocate a new cluster and chain it onto the end of the file.
960 * dep - the file to extend
961 * count - number of clusters to allocate
962 * bpp - where to return the address of the buf header for the first new
964 * ncp - where to put cluster number of the first newly allocated cluster
965 * If this pointer is 0, do not return the cluster number.
968 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of
969 * the de_flag field of the denode and it does not change the de_FileSize
970 * field. This is left for the caller to do.
973 extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp,
979 struct msdosfsmount *pmp = dep->de_pmp;
983 * Don't try to extend the root directory
985 if (dep->de_StartCluster == MSDOSFSROOT
986 && (dep->de_Attributes & ATTR_DIRECTORY)) {
987 kprintf("extendfile(): attempt to extend root directory\n");
992 * If the "file's last cluster" cache entry is empty, and the file
993 * is not empty, then fill the cache entry by calling pcbmap().
995 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY &&
996 dep->de_StartCluster != 0) {
997 error = pcbmap(dep, 0xffff, NULL, &cn, NULL);
998 /* we expect it to return E2BIG */
1003 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn =
1004 dep->de_fc[FC_LASTFC].fc_frcn;
1005 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn =
1006 dep->de_fc[FC_LASTFC].fc_fsrcn;
1009 * Allocate a new cluster chain and cat onto the end of the
1010 * file. If the file is empty we make de_StartCluster point
1011 * to the new block. Note that de_StartCluster being 0 is
1012 * sufficient to be sure the file is empty since we exclude
1013 * attempts to extend the root directory above, and the root
1014 * dir is the only file with a startcluster of 0 that has
1015 * blocks allocated (sort of).
1017 if (dep->de_StartCluster == 0)
1020 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1;
1021 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got);
1028 * Give them the filesystem relative cluster number if they want
1036 if (dep->de_StartCluster == 0) {
1037 dep->de_StartCluster = cn;
1040 error = fatentry(FAT_SET, pmp,
1041 dep->de_fc[FC_LASTFC].fc_fsrcn,
1044 clusterfree(pmp, cn);
1047 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1;
1051 * Update the "last cluster of the file" entry in the
1052 * denode's FAT cache.
1054 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1);
1056 if (flags & DE_CLEAR) {
1059 * Get the buf header for the new block of the file.
1061 if (dep->de_Attributes & ATTR_DIRECTORY) {
1062 bp = getblk(pmp->pm_devvp,
1063 de_bn2doff(pmp, cntobn(pmp, cn)),
1064 pmp->pm_bpcluster, 0, 0);
1070 bp = getblk(DETOV(dep),
1071 de_cn2doff(pmp, frcn),
1072 pmp->pm_bpcluster, 0, 0);
1075 * Convert bio1 offset to file relative
1078 findcn = de_bn2cn(pmp,
1079 (daddr_t)(bp->b_bio1.bio_offset >>
1082 * Do the bmap now, as in msdosfs_write
1084 if (pcbmap(dep, findcn, &dblkno, NULL,
1086 bp->b_bio2.bio_offset = NOOFFSET;
1088 bp->b_bio2.bio_offset = de_bn2doff(pmp, dblkno);
1090 if (bp->b_bio2.bio_offset == NOOFFSET)
1091 panic("extendfile: pcbmap");
1108 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by
1109 * manipulating the upper bit of the FAT entry for cluster 1. Note that
1110 * this bit is not defined for FAT12 volumes, which are always assumed to
1113 * The fatentry() routine only works on cluster numbers that a file could
1114 * occupy, so it won't manipulate the entry for cluster 1. So we have to do
1115 * it here. The code was stolen from fatentry() and tailored for cluster 1.
1118 * pmp The MS-DOS volume to mark
1119 * dirty Non-zero if the volume should be marked dirty; zero if it
1120 * should be marked clean
1124 * EROFS Volume is read-only
1125 * ? (other errors from called routines)
1128 markvoldirty_upgrade(struct msdosfsmount *pmp, bool dirty, bool rw_upgrade)
1131 u_long bn, bo, bsize, byteoffset, fatval;
1135 * FAT12 does not support a "clean" bit, so don't do anything for
1142 * Can't change the bit on a read-only filesystem, except as part of
1145 if ((pmp->pm_flags & MSDOSFSMNT_RONLY) != 0 && !rw_upgrade)
1149 * Fetch the block containing the FAT entry. It is given by the
1152 byteoffset = FATOFS(pmp, 1);
1153 fatblock(pmp, byteoffset, &bn, &bsize, &bo);
1154 error = bread(pmp->pm_devvp, de_bn2doff(pmp, bn), bsize, &bp);
1159 * Get the current value of the FAT entry and set/clear the relevant
1160 * bit. Dirty means clear the "clean" bit; clean means set the
1164 /* FAT32 uses bit 27. */
1165 fatval = getulong(&bp->b_data[bo]);
1167 fatval &= 0xF7FFFFFF;
1169 fatval |= 0x08000000;
1170 putulong(&bp->b_data[bo], fatval);
1172 /* Must be FAT16; use bit 15. */
1173 fatval = getushort(&bp->b_data[bo]);
1178 putushort(&bp->b_data[bo], fatval);
1182 * The concern here is that a devvp may be readonly, without reporting
1183 * itself as such through the usual channels. In that case, we'd like
1184 * it if attempting to mount msdosfs rw didn't panic the system.
1186 * markvoldirty is invoked as the first write on backing devvps when
1187 * either msdosfs is mounted for the first time, or a ro mount is
1190 * In either event, if a write error occurs dirtying the volume:
1191 * - No user data has been permitted to be written to cache yet.
1192 * - We can abort the high-level operation (mount, or ro->rw) safely.
1193 * - We don't derive any benefit from leaving a zombie dirty buf in
1194 * the cache that can not be cleaned or evicted.
1196 * So, mark B_INVALONERR to have bwrite() -> brelse() detect that
1197 * condition and force-invalidate our write to the block if it occurs.
1199 * PR 210316 provides more context on the discovery and diagnosis of
1200 * the problem, as well as earlier attempts to solve it.
1202 bp->b_flags |= B_INVALONERR;
1204 /* Write out the modified FAT block synchronously. */
1205 return (bwrite(bp));