1 /* $FreeBSD: src/sys/msdosfs/msdosfs_fat.c,v 1.23 2000/01/27 14:43:06 nyan Exp $ */
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.
52 * kernel include files.
54 #include <sys/param.h>
55 #include <sys/systm.h>
57 #include <sys/mount.h> /* to define statfs structure */
58 #include <sys/vnode.h> /* to define vattr structure */
63 * msdosfs include files.
66 #include "msdosfsmount.h"
74 static int fc_fileextends
; /* # of file extends */
75 static int fc_lfcempty
; /* # of time last file cluster cache entry
77 static int fc_bmapcalls
; /* # of times pcbmap was called */
80 static int fc_lmdistance
[LMMAX
];/* counters for how far off the last
81 * cluster mapped entry was. */
82 static int fc_largedistance
; /* off by more than LMMAX */
84 static int chainalloc (struct msdosfsmount
*pmp
, u_long start
,
85 u_long count
, u_long fillwith
,
86 u_long
*retcluster
, u_long
*got
);
87 static int chainlength (struct msdosfsmount
*pmp
, u_long start
,
89 static void fatblock (struct msdosfsmount
*pmp
, u_long ofs
,
90 u_long
*bnp
, u_long
*sizep
, u_long
*bop
);
91 static int fatchain (struct msdosfsmount
*pmp
, u_long start
,
92 u_long count
, u_long fillwith
);
93 static void fc_lookup (struct denode
*dep
, u_long findcn
,
94 u_long
*frcnp
, u_long
*fsrcnp
);
95 static void updatefats (struct msdosfsmount
*pmp
, struct buf
*bp
,
98 usemap_alloc (struct msdosfsmount
*pmp
, u_long cn
);
100 usemap_free (struct msdosfsmount
*pmp
, u_long cn
);
103 fatblock(struct msdosfsmount
*pmp
, u_long ofs
, u_long
*bnp
, u_long
*sizep
,
108 bn
= ofs
/ pmp
->pm_fatblocksize
* pmp
->pm_fatblocksec
;
109 size
= min(pmp
->pm_fatblocksec
, pmp
->pm_FATsecs
- bn
)
111 bn
+= pmp
->pm_fatblk
+ pmp
->pm_curfat
* pmp
->pm_FATsecs
;
118 *bop
= ofs
% pmp
->pm_fatblocksize
;
122 * Map the logical cluster number of a file into a physical disk sector
123 * that is filesystem relative.
125 * dep - address of denode representing the file of interest
126 * findcn - file relative cluster whose filesystem relative cluster number
127 * and/or block number are/is to be found
128 * bnp - address of where to place the file system relative block number.
129 * If this pointer is null then don't return this quantity.
130 * cnp - address of where to place the file system relative cluster number.
131 * If this pointer is null then don't return this quantity.
133 * NOTE: Either bnp or cnp must be non-null.
134 * This function has one side effect. If the requested file relative cluster
135 * is beyond the end of file, then the actual number of clusters in the file
136 * is returned in *cnp. This is useful for determining how long a directory is.
137 * If cnp is null, nothing is returned.
140 pcbmap(struct denode
*dep
,
141 u_long findcn
, /* file relative cluster to get */
142 daddr_t
*bnp
, /* returned filesys relative blk number */
143 u_long
*cnp
, /* returned cluster number */
144 int *sp
) /* returned block size */
149 u_long prevcn
= 0; /* XXX: prevcn could be used unititialized */
153 struct buf
*bp
= NULL
;
155 struct msdosfsmount
*pmp
= dep
->de_pmp
;
161 * If they don't give us someplace to return a value then don't
162 * bother doing anything.
164 if (bnp
== NULL
&& cnp
== NULL
&& sp
== NULL
)
167 cn
= dep
->de_StartCluster
;
169 * The "file" that makes up the root directory is contiguous,
170 * permanently allocated, of fixed size, and is not made up of
171 * clusters. If the cluster number is beyond the end of the root
172 * directory, then return the number of clusters in the file.
174 if (cn
== MSDOSFSROOT
) {
175 if (dep
->de_Attributes
& ATTR_DIRECTORY
) {
176 if (de_cn2off(pmp
, findcn
) >= dep
->de_FileSize
) {
178 *cnp
= de_bn2cn(pmp
, pmp
->pm_rootdirsize
);
182 *bnp
= pmp
->pm_rootdirblk
+ de_cn2bn(pmp
, findcn
);
186 *sp
= min(pmp
->pm_bpcluster
,
187 dep
->de_FileSize
- de_cn2off(pmp
, findcn
));
189 } else { /* just an empty file */
197 * All other files do I/O in cluster sized blocks
200 *sp
= pmp
->pm_bpcluster
;
203 * Rummage around in the fat cache, maybe we can avoid tromping
204 * thru every fat entry for the file. And, keep track of how far
205 * off the cache was from where we wanted to be.
208 fc_lookup(dep
, findcn
, &i
, &cn
);
209 if ((bn
= findcn
- i
) >= LMMAX
)
215 * Handle all other files or directories the normal way.
217 for (; i
< findcn
; i
++) {
219 * Stop with all reserved clusters, not just with EOF.
221 if ((cn
| ~pmp
->pm_fatmask
) >= CLUST_RSRVD
)
223 byteoffset
= FATOFS(pmp
, cn
);
224 fatblock(pmp
, byteoffset
, &bn
, &bsize
, &bo
);
228 error
= bread(pmp
->pm_devvp
, de_bntodoff(pmp
, bn
), bsize
, &bp
);
237 cn
= getulong(&bp
->b_data
[bo
]);
239 cn
= getushort(&bp
->b_data
[bo
]);
240 if (FAT12(pmp
) && (prevcn
& 1))
242 cn
&= pmp
->pm_fatmask
;
245 * Force the special cluster numbers
246 * to be the same for all cluster sizes
247 * to let the rest of msdosfs handle
248 * all cases the same.
250 if ((cn
| ~pmp
->pm_fatmask
) >= CLUST_RSRVD
)
251 cn
|= ~pmp
->pm_fatmask
;
254 if (!MSDOSFSEOF(pmp
, cn
)) {
258 *bnp
= xcntobn(pmp
, cn
);
261 fc_setcache(dep
, FC_LASTMAP
, i
, cn
);
270 /* update last file cluster entry in the fat cache */
271 fc_setcache(dep
, FC_LASTFC
, i
- 1, prevcn
);
276 * Find the closest entry in the fat cache to the cluster we are looking
280 fc_lookup(struct denode
*dep
, u_long findcn
, u_long
*frcnp
, u_long
*fsrcnp
)
284 struct fatcache
*closest
= NULL
;
286 for (i
= 0; i
< FC_SIZE
; i
++) {
287 cn
= dep
->de_fc
[i
].fc_frcn
;
288 if (cn
!= FCE_EMPTY
&& cn
<= findcn
) {
289 if (closest
== NULL
|| cn
> closest
->fc_frcn
)
290 closest
= &dep
->de_fc
[i
];
294 *frcnp
= closest
->fc_frcn
;
295 *fsrcnp
= closest
->fc_fsrcn
;
300 * Purge the fat cache in denode dep of all entries relating to file
301 * relative cluster frcn and beyond.
304 fc_purge(struct denode
*dep
, u_int frcn
)
307 struct fatcache
*fcp
;
310 for (i
= 0; i
< FC_SIZE
; i
++, fcp
++) {
311 if (fcp
->fc_frcn
>= frcn
)
312 fcp
->fc_frcn
= FCE_EMPTY
;
318 * If mirroring the fat, update all copies, with the first copy as last.
319 * Else update only the current fat (ignoring the others).
321 * pmp - msdosfsmount structure for filesystem to update
322 * bp - addr of modified fat block
323 * fatbn - block number relative to begin of filesystem of the modified fat block.
326 updatefats(struct msdosfsmount
*pmp
, struct buf
*bp
, u_long fatbn
)
332 kprintf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp
, bp
, fatbn
);
336 * If we have an FSInfo block, update it.
338 if (pmp
->pm_fsinfo
) {
339 u_long cn
= pmp
->pm_nxtfree
;
341 if (pmp
->pm_freeclustercount
342 && (pmp
->pm_inusemap
[cn
/ N_INUSEBITS
]
343 & (1 << (cn
% N_INUSEBITS
)))) {
345 * The cluster indicated in FSInfo isn't free
346 * any longer. Got get a new free one.
348 for (cn
= 0; cn
< pmp
->pm_maxcluster
; cn
+= N_INUSEBITS
)
349 if (pmp
->pm_inusemap
[cn
/ N_INUSEBITS
] != (u_int
)-1)
352 + ffs(pmp
->pm_inusemap
[cn
/ N_INUSEBITS
]
355 if (bread(pmp
->pm_devvp
, de_bntodoff(pmp
, pmp
->pm_fsinfo
), fsi_size(pmp
), &bpn
) != 0) {
357 * Ignore the error, but turn off FSInfo update for the future.
362 struct fsinfo
*fp
= (struct fsinfo
*)bpn
->b_data
;
364 putulong(fp
->fsinfree
, pmp
->pm_freeclustercount
);
365 putulong(fp
->fsinxtfree
, pmp
->pm_nxtfree
);
366 if (pmp
->pm_flags
& MSDOSFSMNT_WAITONFAT
)
373 if (pmp
->pm_flags
& MSDOSFS_FATMIRROR
) {
375 * Now copy the block(s) of the modified fat to the other copies of
376 * the fat and write them out. This is faster than reading in the
377 * other fats and then writing them back out. This could tie up
378 * the fat for quite a while. Preventing others from accessing it.
379 * To prevent us from going after the fat quite so much we use
380 * delayed writes, unless they specfied "synchronous" when the
381 * filesystem was mounted. If synch is asked for then use
382 * bwrite()'s and really slow things down.
384 for (i
= 1; i
< pmp
->pm_FATs
; i
++) {
385 fatbn
+= pmp
->pm_FATsecs
;
386 /* getblk() never fails */
387 bpn
= getblk(pmp
->pm_devvp
, de_bntodoff(pmp
, fatbn
),
389 bcopy(bp
->b_data
, bpn
->b_data
, bp
->b_bcount
);
390 if (pmp
->pm_flags
& MSDOSFSMNT_WAITONFAT
)
398 * Write out the first (or current) fat last.
400 if (pmp
->pm_flags
& MSDOSFSMNT_WAITONFAT
)
405 * Maybe update fsinfo sector here?
410 * Updating entries in 12 bit fats is a pain in the butt.
412 * The following picture shows where nibbles go when moving from a 12 bit
413 * cluster number into the appropriate bytes in the FAT.
415 * byte m byte m+1 byte m+2
416 * +----+----+ +----+----+ +----+----+
417 * | 0 1 | | 2 3 | | 4 5 | FAT bytes
418 * +----+----+ +----+----+ +----+----+
420 * +----+----+----+ +----+----+----+
421 * | 3 0 1 | | 4 5 2 |
422 * +----+----+----+ +----+----+----+
423 * cluster n cluster n+1
425 * Where n is even. m = n + (n >> 2)
429 usemap_alloc(struct msdosfsmount
*pmp
, u_long cn
)
432 pmp
->pm_inusemap
[cn
/ N_INUSEBITS
] |= 1 << (cn
% N_INUSEBITS
);
433 pmp
->pm_freeclustercount
--;
437 usemap_free(struct msdosfsmount
*pmp
, u_long cn
)
440 pmp
->pm_freeclustercount
++;
441 pmp
->pm_inusemap
[cn
/ N_INUSEBITS
] &= ~(1 << (cn
% N_INUSEBITS
));
445 clusterfree(struct msdosfsmount
*pmp
, u_long cluster
, u_long
*oldcnp
)
450 usemap_free(pmp
, cluster
);
451 error
= fatentry(FAT_GET_AND_SET
, pmp
, cluster
, &oldcn
, MSDOSFSFREE
);
453 usemap_alloc(pmp
, cluster
);
457 * If the cluster was successfully marked free, then update
458 * the count of free clusters, and turn off the "allocated"
459 * bit in the "in use" cluster bit map.
467 * Get or Set or 'Get and Set' the cluster'th entry in the fat.
469 * function - whether to get or set a fat entry
470 * pmp - address of the msdosfsmount structure for the filesystem
471 * whose fat is to be manipulated.
472 * cn - which cluster is of interest
473 * oldcontents - address of a word that is to receive the contents of the
474 * cluster'th entry if this is a get function
475 * newcontents - the new value to be written into the cluster'th element of
476 * the fat if this is a set function.
478 * This function can also be used to free a cluster by setting the fat entry
479 * for a cluster to 0.
481 * All copies of the fat are updated if this is a set function. NOTE: If
482 * fatentry() marks a cluster as free it does not update the inusemap in
483 * the msdosfsmount structure. This is left to the caller.
486 fatentry(int function
, struct msdosfsmount
*pmp
, u_long cn
, u_long
*oldcontents
,
491 u_long bn
, bo
, bsize
, byteoffset
;
495 kprintf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n",
496 function
, pmp
, cn
, oldcontents
, newcontents
);
501 * Be sure they asked us to do something.
503 if ((function
& (FAT_SET
| FAT_GET
)) == 0) {
504 kprintf("fatentry(): function code doesn't specify get or set\n");
509 * If they asked us to return a cluster number but didn't tell us
510 * where to put it, give them an error.
512 if ((function
& FAT_GET
) && oldcontents
== NULL
) {
513 kprintf("fatentry(): get function with no place to put result\n");
519 * Be sure the requested cluster is in the filesystem.
521 if (cn
< CLUST_FIRST
|| cn
> pmp
->pm_maxcluster
)
524 byteoffset
= FATOFS(pmp
, cn
);
525 fatblock(pmp
, byteoffset
, &bn
, &bsize
, &bo
);
526 error
= bread(pmp
->pm_devvp
, de_bntodoff(pmp
, bn
), bsize
, &bp
);
532 if (function
& FAT_GET
) {
534 readcn
= getulong(&bp
->b_data
[bo
]);
536 readcn
= getushort(&bp
->b_data
[bo
]);
537 if (FAT12(pmp
) & (cn
& 1))
539 readcn
&= pmp
->pm_fatmask
;
540 /* map reserved fat entries to same values for all fats */
541 if ((readcn
| ~pmp
->pm_fatmask
) >= CLUST_RSRVD
)
542 readcn
|= ~pmp
->pm_fatmask
;
543 *oldcontents
= readcn
;
545 if (function
& FAT_SET
) {
546 switch (pmp
->pm_fatmask
) {
548 readcn
= getushort(&bp
->b_data
[bo
]);
551 readcn
|= newcontents
<< 4;
554 readcn
|= newcontents
& 0xfff;
556 putushort(&bp
->b_data
[bo
], readcn
);
559 putushort(&bp
->b_data
[bo
], newcontents
);
563 * According to spec we have to retain the
564 * high order bits of the fat entry.
566 readcn
= getulong(&bp
->b_data
[bo
]);
567 readcn
&= ~FAT32_MASK
;
568 readcn
|= newcontents
& FAT32_MASK
;
569 putulong(&bp
->b_data
[bo
], readcn
);
572 updatefats(pmp
, bp
, bn
);
582 * Update a contiguous cluster chain
585 * start - first cluster of chain
586 * count - number of clusters in chain
587 * fillwith - what to write into fat entry of last cluster
590 fatchain(struct msdosfsmount
*pmp
, u_long start
, u_long count
, u_long fillwith
)
593 u_long bn
, bo
, bsize
, byteoffset
, readcn
, newc
;
597 kprintf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n",
598 pmp
, start
, count
, fillwith
);
601 * Be sure the clusters are in the filesystem.
603 if (start
< CLUST_FIRST
|| start
+ count
- 1 > pmp
->pm_maxcluster
)
607 byteoffset
= FATOFS(pmp
, start
);
608 fatblock(pmp
, byteoffset
, &bn
, &bsize
, &bo
);
609 error
= bread(pmp
->pm_devvp
, de_bntodoff(pmp
, bn
), bsize
, &bp
);
616 newc
= --count
> 0 ? start
: fillwith
;
617 switch (pmp
->pm_fatmask
) {
619 readcn
= getushort(&bp
->b_data
[bo
]);
622 readcn
|= newc
& 0xfff;
627 putushort(&bp
->b_data
[bo
], readcn
);
633 putushort(&bp
->b_data
[bo
], newc
);
637 readcn
= getulong(&bp
->b_data
[bo
]);
638 readcn
&= ~pmp
->pm_fatmask
;
639 readcn
|= newc
& pmp
->pm_fatmask
;
640 putulong(&bp
->b_data
[bo
], readcn
);
647 updatefats(pmp
, bp
, bn
);
654 * Check the length of a free cluster chain starting at start.
657 * start - start of chain
658 * count - maximum interesting length
661 chainlength(struct msdosfsmount
*pmp
, u_long start
, u_long count
)
667 max_idx
= pmp
->pm_maxcluster
/ N_INUSEBITS
;
668 idx
= start
/ N_INUSEBITS
;
669 start
%= N_INUSEBITS
;
670 map
= pmp
->pm_inusemap
[idx
];
671 map
&= ~((1 << start
) - 1);
673 len
= ffs(map
) - 1 - start
;
674 return (len
> count
? count
: len
);
676 len
= N_INUSEBITS
- start
;
679 while (++idx
<= max_idx
) {
682 map
= pmp
->pm_inusemap
[idx
];
689 return (len
> count
? count
: len
);
693 * Allocate contigous free clusters.
696 * start - start of cluster chain.
697 * count - number of clusters to allocate.
698 * fillwith - put this value into the fat entry for the
699 * last allocated cluster.
700 * retcluster - put the first allocated cluster's number here.
701 * got - how many clusters were actually allocated.
704 chainalloc(struct msdosfsmount
*pmp
, u_long start
, u_long count
,
705 u_long fillwith
, u_long
*retcluster
, u_long
*got
)
710 for (cl
= start
, n
= count
; n
-- > 0;)
711 usemap_alloc(pmp
, cl
++);
713 error
= fatchain(pmp
, start
, count
, fillwith
);
717 kprintf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n",
728 * Allocate contiguous free clusters.
731 * start - preferred start of cluster chain.
732 * count - number of clusters requested.
733 * fillwith - put this value into the fat entry for the
734 * last allocated cluster.
735 * retcluster - put the first allocated cluster's number here.
736 * got - how many clusters were actually allocated.
739 clusteralloc(struct msdosfsmount
*pmp
, u_long start
, u_long count
,
740 u_long fillwith
, u_long
*retcluster
, u_long
*got
)
743 u_long len
, newst
, foundl
, cn
, l
;
744 u_long foundcn
= 0; /* XXX: foundcn could be used unititialized */
748 kprintf("clusteralloc(): find %lu clusters\n",count
);
751 if ((len
= chainlength(pmp
, start
, count
)) >= count
)
752 return (chainalloc(pmp
, start
, count
, fillwith
, retcluster
, got
));
757 * Start at a (pseudo) random place to maximize cluster runs
758 * under multiple writers.
760 newst
= krandom() % (pmp
->pm_maxcluster
+ 1);
763 for (cn
= newst
; cn
<= pmp
->pm_maxcluster
;) {
764 idx
= cn
/ N_INUSEBITS
;
765 map
= pmp
->pm_inusemap
[idx
];
766 map
|= (1 << (cn
% N_INUSEBITS
)) - 1;
767 if (map
!= (u_int
)-1) {
768 cn
= idx
* N_INUSEBITS
+ ffs(map
^(u_int
)-1) - 1;
769 if ((l
= chainlength(pmp
, cn
, count
)) >= count
)
770 return (chainalloc(pmp
, cn
, count
, fillwith
, retcluster
, got
));
778 cn
+= N_INUSEBITS
- cn
% N_INUSEBITS
;
780 for (cn
= 0; cn
< newst
;) {
781 idx
= cn
/ N_INUSEBITS
;
782 map
= pmp
->pm_inusemap
[idx
];
783 map
|= (1 << (cn
% N_INUSEBITS
)) - 1;
784 if (map
!= (u_int
)-1) {
785 cn
= idx
* N_INUSEBITS
+ ffs(map
^(u_int
)-1) - 1;
786 if ((l
= chainlength(pmp
, cn
, count
)) >= count
)
787 return (chainalloc(pmp
, cn
, count
, fillwith
, retcluster
, got
));
795 cn
+= N_INUSEBITS
- cn
% N_INUSEBITS
;
802 return (chainalloc(pmp
, start
, len
, fillwith
, retcluster
, got
));
804 return (chainalloc(pmp
, foundcn
, foundl
, fillwith
, retcluster
, got
));
809 * Free a chain of clusters.
811 * pmp - address of the msdosfs mount structure for the filesystem
812 * containing the cluster chain to be freed.
813 * startcluster - number of the 1st cluster in the chain of clusters to be
817 freeclusterchain(struct msdosfsmount
*pmp
, u_long cluster
)
820 struct buf
*bp
= NULL
;
821 u_long bn
, bo
, bsize
, byteoffset
;
822 u_long readcn
, lbn
= -1;
824 while (cluster
>= CLUST_FIRST
&& cluster
<= pmp
->pm_maxcluster
) {
825 byteoffset
= FATOFS(pmp
, cluster
);
826 fatblock(pmp
, byteoffset
, &bn
, &bsize
, &bo
);
829 updatefats(pmp
, bp
, lbn
);
830 error
= bread(pmp
->pm_devvp
, de_bntodoff(pmp
, bn
), bsize
, &bp
);
837 usemap_free(pmp
, cluster
);
838 switch (pmp
->pm_fatmask
) {
840 readcn
= getushort(&bp
->b_data
[bo
]);
842 cluster
= readcn
>> 4;
844 readcn
|= MSDOSFSFREE
<< 4;
848 readcn
|= MSDOSFSFREE
& 0xfff;
850 putushort(&bp
->b_data
[bo
], readcn
);
853 cluster
= getushort(&bp
->b_data
[bo
]);
854 putushort(&bp
->b_data
[bo
], MSDOSFSFREE
);
857 cluster
= getulong(&bp
->b_data
[bo
]);
858 putulong(&bp
->b_data
[bo
],
859 (MSDOSFSFREE
& FAT32_MASK
) | (cluster
& ~FAT32_MASK
));
862 cluster
&= pmp
->pm_fatmask
;
863 if ((cluster
| ~pmp
->pm_fatmask
) >= CLUST_RSRVD
)
864 cluster
|= pmp
->pm_fatmask
;
867 updatefats(pmp
, bp
, bn
);
872 * Read in fat blocks looking for free clusters. For every free cluster
873 * found turn off its corresponding bit in the pm_inusemap.
876 fillinusemap(struct msdosfsmount
*pmp
)
878 struct buf
*bp
= NULL
;
881 u_long bn
, bo
, bsize
, byteoffset
;
884 * Mark all clusters in use, we mark the free ones in the fat scan
887 for (cn
= 0; cn
< (pmp
->pm_maxcluster
+ N_INUSEBITS
) / N_INUSEBITS
; cn
++)
888 pmp
->pm_inusemap
[cn
] = (u_int
)-1;
891 * Figure how many free clusters are in the filesystem by ripping
892 * through the fat counting the number of entries whose content is
893 * zero. These represent free clusters.
895 pmp
->pm_freeclustercount
= 0;
896 for (cn
= CLUST_FIRST
; cn
<= pmp
->pm_maxcluster
; cn
++) {
897 byteoffset
= FATOFS(pmp
, cn
);
898 bo
= byteoffset
% pmp
->pm_fatblocksize
;
900 /* Read new FAT block */
903 fatblock(pmp
, byteoffset
, &bn
, &bsize
, NULL
);
904 error
= bread(pmp
->pm_devvp
, de_bntodoff(pmp
, bn
), bsize
, &bp
);
911 readcn
= getulong(&bp
->b_data
[bo
]);
913 readcn
= getushort(&bp
->b_data
[bo
]);
914 if (FAT12(pmp
) && (cn
& 1))
916 readcn
&= pmp
->pm_fatmask
;
919 usemap_free(pmp
, cn
);
926 * Allocate a new cluster and chain it onto the end of the file.
928 * dep - the file to extend
929 * count - number of clusters to allocate
930 * bpp - where to return the address of the buf header for the first new
932 * ncp - where to put cluster number of the first newly allocated cluster
933 * If this pointer is 0, do not return the cluster number.
936 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of
937 * the de_flag field of the denode and it does not change the de_FileSize
938 * field. This is left for the caller to do.
941 extendfile(struct denode
*dep
, u_long count
, struct buf
**bpp
, u_long
*ncp
,
947 struct msdosfsmount
*pmp
= dep
->de_pmp
;
951 * Don't try to extend the root directory
953 if (dep
->de_StartCluster
== MSDOSFSROOT
954 && (dep
->de_Attributes
& ATTR_DIRECTORY
)) {
955 kprintf("extendfile(): attempt to extend root directory\n");
960 * If the "file's last cluster" cache entry is empty, and the file
961 * is not empty, then fill the cache entry by calling pcbmap().
964 if (dep
->de_fc
[FC_LASTFC
].fc_frcn
== FCE_EMPTY
&&
965 dep
->de_StartCluster
!= 0) {
967 error
= pcbmap(dep
, 0xffff, NULL
, &cn
, NULL
);
968 /* we expect it to return E2BIG */
975 * Allocate a new cluster chain and cat onto the end of the
976 * file. * If the file is empty we make de_StartCluster point
977 * to the new block. Note that de_StartCluster being 0 is
978 * sufficient to be sure the file is empty since we exclude
979 * attempts to extend the root directory above, and the root
980 * dir is the only file with a startcluster of 0 that has
981 * blocks allocated (sort of).
983 if (dep
->de_StartCluster
== 0)
986 cn
= dep
->de_fc
[FC_LASTFC
].fc_fsrcn
+ 1;
987 error
= clusteralloc(pmp
, cn
, count
, CLUST_EOFE
, &cn
, &got
);
994 * Give them the filesystem relative cluster number if they want
1002 if (dep
->de_StartCluster
== 0) {
1003 dep
->de_StartCluster
= cn
;
1006 error
= fatentry(FAT_SET
, pmp
,
1007 dep
->de_fc
[FC_LASTFC
].fc_fsrcn
,
1010 clusterfree(pmp
, cn
, NULL
);
1013 frcn
= dep
->de_fc
[FC_LASTFC
].fc_frcn
+ 1;
1017 * Update the "last cluster of the file" entry in the
1018 * denode's fat cache.
1020 fc_setcache(dep
, FC_LASTFC
, frcn
+ got
- 1, cn
+ got
- 1);
1022 if (flags
& DE_CLEAR
) {
1025 * Get the buf header for the new block of the file.
1027 if (dep
->de_Attributes
& ATTR_DIRECTORY
) {
1028 bp
= getblk(pmp
->pm_devvp
,
1030 pmp
->pm_bpcluster
, 0, 0);
1035 bp
= getblk(DETOV(dep
),
1036 de_cn2doff(pmp
, frcn
),
1037 pmp
->pm_bpcluster
, 0, 0);
1040 * Do the bmap now, as in msdosfs_write
1043 de_bn2cn(pmp
, de_off2bn(pmp
, bp
->b_bio1
.bio_offset
)),
1044 &dblkno
, NULL
, NULL
)) {
1045 bp
->b_bio2
.bio_offset
= NOOFFSET
;
1047 bp
->b_bio2
.bio_offset
= de_bntodoff(pmp
, dblkno
);
1049 if (bp
->b_bio2
.bio_offset
== NOOFFSET
)
1050 panic("extendfile: pcbmap");