msdosfs_fat.c revision 171753
1/* $FreeBSD: head/sys/fs/msdosfs/msdosfs_fat.c 171752 2007-08-07 02:20:37Z bde $ */ 2/* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 ws Exp $ */ 3 4/*- 5 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank. 6 * Copyright (C) 1994, 1995, 1997 TooLs GmbH. 7 * All rights reserved. 8 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below). 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 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. 23 * 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. 34 */ 35/*- 36 * Written by Paul Popelka (paulp@uts.amdahl.com) 37 * 38 * You can do anything you want with this software, just don't say you wrote 39 * it, and don't remove this notice. 40 * 41 * This software is provided "as is". 42 * 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. 47 * 48 * October 1992 49 */ 50 51#include <sys/param.h> 52#include <sys/systm.h> 53#include <sys/buf.h> 54#include <sys/mount.h> 55#include <sys/vnode.h> 56 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> 62 63/* 64 * Fat cache stats. 65 */ 66static int fc_fileextends; /* # of file extends */ 67static int fc_lfcempty; /* # of time last file cluster cache entry 68 * was empty */ 69static int fc_bmapcalls; /* # of times pcbmap was called */ 70 71#define LMMAX 20 72static int fc_lmdistance[LMMAX];/* counters for how far off the last 73 * cluster mapped entry was. */ 74static int fc_largedistance; /* off by more than LMMAX */ 75static int fc_wherefrom, fc_whereto, fc_lastclust; 76static int pm_fatblocksize; 77 78static int chainalloc(struct msdosfsmount *pmp, u_long start, 79 u_long count, u_long fillwith, u_long *retcluster, 80 u_long *got); 81static int chainlength(struct msdosfsmount *pmp, u_long start, 82 u_long count); 83static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 84 u_long *sizep, u_long *bop); 85static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 86 u_long fillwith); 87static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 88 u_long *fsrcnp); 89static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 90 u_long fatbn); 91static __inline void 92 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 93static __inline void 94 usemap_free(struct msdosfsmount *pmp, u_long cn); 95 96static void 97fatblock(pmp, ofs, bnp, sizep, bop) 98 struct msdosfsmount *pmp; 99 u_long ofs; 100 u_long *bnp; 101 u_long *sizep; 102 u_long *bop; 103{ 104 u_long bn, size; 105 106 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 107 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 108 * DEV_BSIZE; 109 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 110 111 if (bnp) 112 *bnp = bn; 113 if (sizep) 114 *sizep = size; 115 if (bop) 116 *bop = ofs % pmp->pm_fatblocksize; 117 pm_fatblocksize = pmp->pm_fatblocksize; 118} 119 120/* 121 * Map the logical cluster number of a file into a physical disk sector 122 * that is filesystem relative. 123 * 124 * dep - address of denode representing the file of interest 125 * findcn - file relative cluster whose filesystem relative cluster number 126 * and/or block number are/is to be found 127 * bnp - address of where to place the filesystem relative block number. 128 * If this pointer is null then don't return this quantity. 129 * cnp - address of where to place the filesystem relative cluster number. 130 * If this pointer is null then don't return this quantity. 131 * 132 * NOTE: Either bnp or cnp must be non-null. 133 * This function has one side effect. If the requested file relative cluster 134 * is beyond the end of file, then the actual number of clusters in the file 135 * is returned in *cnp. This is useful for determining how long a directory is. 136 * If cnp is null, nothing is returned. 137 */ 138int 139pcbmap(dep, findcn, bnp, cnp, sp) 140 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 */ 145{ 146 int error; 147 u_long i; 148 u_long cn; 149 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 150 u_long byteoffset; 151 u_long bn; 152 u_long bo; 153 struct buf *bp = NULL; 154 u_long bp_bn = -1; 155 struct msdosfsmount *pmp = dep->de_pmp; 156 u_long bsize; 157 158 fc_bmapcalls++; 159 160 /* 161 * If they don't give us someplace to return a value then don't 162 * bother doing anything. 163 */ 164 if (bnp == NULL && cnp == NULL && sp == NULL) 165 return (0); 166 167 cn = dep->de_StartCluster; 168 /* 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. 173 */ 174 if (cn == MSDOSFSROOT) { 175 if (dep->de_Attributes & ATTR_DIRECTORY) { 176 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 177 if (cnp) 178 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 179 return (E2BIG); 180 } 181 if (bnp) 182 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 183 if (cnp) 184 *cnp = MSDOSFSROOT; 185 if (sp) 186 *sp = min(pmp->pm_bpcluster, 187 dep->de_FileSize - de_cn2off(pmp, findcn)); 188 return (0); 189 } else { /* just an empty file */ 190 if (cnp) 191 *cnp = 0; 192 return (E2BIG); 193 } 194 } 195 196 /* 197 * All other files do I/O in cluster sized blocks 198 */ 199 if (sp) 200 *sp = pmp->pm_bpcluster; 201 202 /* 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. 206 */ 207 i = 0; 208 fc_lookup(dep, findcn, &i, &cn); 209 if ((bn = findcn - i) >= LMMAX) { 210 fc_largedistance++; 211 fc_wherefrom = i; 212 fc_whereto = findcn; 213 fc_lastclust = dep->de_fc[FC_LASTFC].fc_frcn; 214 } else 215 fc_lmdistance[bn]++; 216 217 /* 218 * Handle all other files or directories the normal way. 219 */ 220 for (; i < findcn; i++) { 221 /* 222 * Stop with all reserved clusters, not just with EOF. 223 */ 224 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 225 goto hiteof; 226 byteoffset = FATOFS(pmp, cn); 227 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 228 if (bn != bp_bn) { 229 if (bp) 230 brelse(bp); 231 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 232 if (error) { 233 brelse(bp); 234 return (error); 235 } 236 bp_bn = bn; 237 } 238 prevcn = cn; 239 if (bo >= bsize) { 240 if (bp) 241 brelse(bp); 242 return (EIO); 243 } 244 if (FAT32(pmp)) 245 cn = getulong(&bp->b_data[bo]); 246 else 247 cn = getushort(&bp->b_data[bo]); 248 if (FAT12(pmp) && (prevcn & 1)) 249 cn >>= 4; 250 cn &= pmp->pm_fatmask; 251 252 /* 253 * Force the special cluster numbers 254 * to be the same for all cluster sizes 255 * to let the rest of msdosfs handle 256 * all cases the same. 257 */ 258 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 259 cn |= ~pmp->pm_fatmask; 260 } 261 262 if (!MSDOSFSEOF(pmp, cn)) { 263 if (bp) 264 brelse(bp); 265 if (bnp) 266 *bnp = cntobn(pmp, cn); 267 if (cnp) 268 *cnp = cn; 269 fc_setcache(dep, FC_LASTMAP, i, cn); 270 return (0); 271 } 272 273hiteof:; 274 if (cnp) 275 *cnp = i; 276 if (bp) 277 brelse(bp); 278 /* update last file cluster entry in the fat cache */ 279 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 280 return (E2BIG); 281} 282 283/* 284 * Find the closest entry in the fat cache to the cluster we are looking 285 * for. 286 */ 287static void 288fc_lookup(dep, findcn, frcnp, fsrcnp) 289 struct denode *dep; 290 u_long findcn; 291 u_long *frcnp; 292 u_long *fsrcnp; 293{ 294 int i; 295 u_long cn; 296 struct fatcache *closest = 0; 297 298 for (i = 0; i < FC_SIZE; i++) { 299 cn = dep->de_fc[i].fc_frcn; 300 if (cn != FCE_EMPTY && cn <= findcn) { 301 if (closest == 0 || cn > closest->fc_frcn) 302 closest = &dep->de_fc[i]; 303 } 304 } 305 if (closest) { 306 *frcnp = closest->fc_frcn; 307 *fsrcnp = closest->fc_fsrcn; 308 } 309} 310 311/* 312 * Purge the fat cache in denode dep of all entries relating to file 313 * relative cluster frcn and beyond. 314 */ 315void 316fc_purge(dep, frcn) 317 struct denode *dep; 318 u_int frcn; 319{ 320 int i; 321 struct fatcache *fcp; 322 323 fcp = dep->de_fc; 324 for (i = 0; i < FC_SIZE; i++, fcp++) { 325 if (fcp->fc_frcn >= frcn) 326 fcp->fc_frcn = FCE_EMPTY; 327 } 328} 329 330/* 331 * Update the fat. 332 * If mirroring the fat, update all copies, with the first copy as last. 333 * Else update only the current fat (ignoring the others). 334 * 335 * pmp - msdosfsmount structure for filesystem to update 336 * bp - addr of modified fat block 337 * fatbn - block number relative to begin of filesystem of the modified fat block. 338 */ 339static void 340updatefats(pmp, bp, fatbn) 341 struct msdosfsmount *pmp; 342 struct buf *bp; 343 u_long fatbn; 344{ 345 int i; 346 struct buf *bpn; 347 348#ifdef MSDOSFS_DEBUG 349 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 350#endif 351 352 /* 353 * If we have an FSInfo block, update it. 354 */ 355 if (pmp->pm_fsinfo) { 356 u_long cn = pmp->pm_nxtfree; 357 358 if (pmp->pm_freeclustercount 359 && (pmp->pm_inusemap[cn / N_INUSEBITS] 360 & (1 << (cn % N_INUSEBITS)))) { 361 /* 362 * The cluster indicated in FSInfo isn't free 363 * any longer. Got get a new free one. 364 */ 365 for (cn = 0; cn < pmp->pm_maxcluster; cn += N_INUSEBITS) 366 if (pmp->pm_inusemap[cn / N_INUSEBITS] != (u_int)-1) 367 break; 368 pmp->pm_nxtfree = cn 369 + ffs(pmp->pm_inusemap[cn / N_INUSEBITS] 370 ^ (u_int)-1) - 1; 371 } 372 if (bread(pmp->pm_devvp, pmp->pm_fsinfo, pmp->pm_BytesPerSec, 373 NOCRED, &bpn) != 0) { 374 /* 375 * Ignore the error, but turn off FSInfo update for the future. 376 */ 377 pmp->pm_fsinfo = 0; 378 brelse(bpn); 379 } else { 380 struct fsinfo *fp = (struct fsinfo *)bpn->b_data; 381 382 putulong(fp->fsinfree, pmp->pm_freeclustercount); 383 putulong(fp->fsinxtfree, pmp->pm_nxtfree); 384 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 385 bwrite(bpn); 386 else 387 bdwrite(bpn); 388 } 389 } 390 391 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 392 /* 393 * Now copy the block(s) of the modified fat to the other copies of 394 * the fat and write them out. This is faster than reading in the 395 * other fats and then writing them back out. This could tie up 396 * the fat for quite a while. Preventing others from accessing it. 397 * To prevent us from going after the fat quite so much we use 398 * delayed writes, unless they specfied "synchronous" when the 399 * filesystem was mounted. If synch is asked for then use 400 * bwrite()'s and really slow things down. 401 */ 402 for (i = 1; i < pmp->pm_FATs; i++) { 403 fatbn += pmp->pm_FATsecs; 404 /* getblk() never fails */ 405 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 406 0, 0, 0); 407 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 408 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 409 bwrite(bpn); 410 else 411 bdwrite(bpn); 412 } 413 } 414 415 /* 416 * Write out the first (or current) fat last. 417 */ 418 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 419 bwrite(bp); 420 else 421 bdwrite(bp); 422 /* 423 * Maybe update fsinfo sector here? 424 */ 425} 426 427/* 428 * Updating entries in 12 bit fats is a pain in the butt. 429 * 430 * The following picture shows where nibbles go when moving from a 12 bit 431 * cluster number into the appropriate bytes in the FAT. 432 * 433 * byte m byte m+1 byte m+2 434 * +----+----+ +----+----+ +----+----+ 435 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 436 * +----+----+ +----+----+ +----+----+ 437 * 438 * +----+----+----+ +----+----+----+ 439 * | 3 0 1 | | 4 5 2 | 440 * +----+----+----+ +----+----+----+ 441 * cluster n cluster n+1 442 * 443 * Where n is even. m = n + (n >> 2) 444 * 445 */ 446static __inline void 447usemap_alloc(pmp, cn) 448 struct msdosfsmount *pmp; 449 u_long cn; 450{ 451 452 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 453 pmp->pm_freeclustercount--; 454} 455 456static __inline void 457usemap_free(pmp, cn) 458 struct msdosfsmount *pmp; 459 u_long cn; 460{ 461 462 pmp->pm_freeclustercount++; 463 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 464} 465 466int 467clusterfree(pmp, cluster, oldcnp) 468 struct msdosfsmount *pmp; 469 u_long cluster; 470 u_long *oldcnp; 471{ 472 int error; 473 u_long oldcn; 474 475 usemap_free(pmp, cluster); 476 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 477 if (error) { 478 usemap_alloc(pmp, cluster); 479 return (error); 480 } 481 /* 482 * If the cluster was successfully marked free, then update 483 * the count of free clusters, and turn off the "allocated" 484 * bit in the "in use" cluster bit map. 485 */ 486 if (oldcnp) 487 *oldcnp = oldcn; 488 return (0); 489} 490 491/* 492 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 493 * 494 * function - whether to get or set a fat entry 495 * pmp - address of the msdosfsmount structure for the filesystem 496 * whose fat is to be manipulated. 497 * cn - which cluster is of interest 498 * oldcontents - address of a word that is to receive the contents of the 499 * cluster'th entry if this is a get function 500 * newcontents - the new value to be written into the cluster'th element of 501 * the fat if this is a set function. 502 * 503 * This function can also be used to free a cluster by setting the fat entry 504 * for a cluster to 0. 505 * 506 * All copies of the fat are updated if this is a set function. NOTE: If 507 * fatentry() marks a cluster as free it does not update the inusemap in 508 * the msdosfsmount structure. This is left to the caller. 509 */ 510int 511fatentry(function, pmp, cn, oldcontents, newcontents) 512 int function; 513 struct msdosfsmount *pmp; 514 u_long cn; 515 u_long *oldcontents; 516 u_long newcontents; 517{ 518 int error; 519 u_long readcn; 520 u_long bn, bo, bsize, byteoffset; 521 struct buf *bp; 522 523#ifdef MSDOSFS_DEBUG 524 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 525 function, pmp, cn, oldcontents, newcontents); 526#endif 527 528#ifdef DIAGNOSTIC 529 /* 530 * Be sure they asked us to do something. 531 */ 532 if ((function & (FAT_SET | FAT_GET)) == 0) { 533 printf("fatentry(): function code doesn't specify get or set\n"); 534 return (EINVAL); 535 } 536 537 /* 538 * If they asked us to return a cluster number but didn't tell us 539 * where to put it, give them an error. 540 */ 541 if ((function & FAT_GET) && oldcontents == NULL) { 542 printf("fatentry(): get function with no place to put result\n"); 543 return (EINVAL); 544 } 545#endif 546 547 /* 548 * Be sure the requested cluster is in the filesystem. 549 */ 550 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 551 return (EINVAL); 552 553 byteoffset = FATOFS(pmp, cn); 554 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 555 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 556 if (error) { 557 brelse(bp); 558 return (error); 559 } 560 561 if (function & FAT_GET) { 562 if (FAT32(pmp)) 563 readcn = getulong(&bp->b_data[bo]); 564 else 565 readcn = getushort(&bp->b_data[bo]); 566 if (FAT12(pmp) & (cn & 1)) 567 readcn >>= 4; 568 readcn &= pmp->pm_fatmask; 569 /* map reserved fat entries to same values for all fats */ 570 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 571 readcn |= ~pmp->pm_fatmask; 572 *oldcontents = readcn; 573 } 574 if (function & FAT_SET) { 575 switch (pmp->pm_fatmask) { 576 case FAT12_MASK: 577 readcn = getushort(&bp->b_data[bo]); 578 if (cn & 1) { 579 readcn &= 0x000f; 580 readcn |= newcontents << 4; 581 } else { 582 readcn &= 0xf000; 583 readcn |= newcontents & 0xfff; 584 } 585 putushort(&bp->b_data[bo], readcn); 586 break; 587 case FAT16_MASK: 588 putushort(&bp->b_data[bo], newcontents); 589 break; 590 case FAT32_MASK: 591 /* 592 * According to spec we have to retain the 593 * high order bits of the fat entry. 594 */ 595 readcn = getulong(&bp->b_data[bo]); 596 readcn &= ~FAT32_MASK; 597 readcn |= newcontents & FAT32_MASK; 598 putulong(&bp->b_data[bo], readcn); 599 break; 600 } 601 updatefats(pmp, bp, bn); 602 bp = NULL; 603 pmp->pm_fmod = 1; 604 } 605 if (bp) 606 brelse(bp); 607 return (0); 608} 609 610/* 611 * Update a contiguous cluster chain 612 * 613 * pmp - mount point 614 * start - first cluster of chain 615 * count - number of clusters in chain 616 * fillwith - what to write into fat entry of last cluster 617 */ 618static int 619fatchain(pmp, start, count, fillwith) 620 struct msdosfsmount *pmp; 621 u_long start; 622 u_long count; 623 u_long fillwith; 624{ 625 int error; 626 u_long bn, bo, bsize, byteoffset, readcn, newc; 627 struct buf *bp; 628 629#ifdef MSDOSFS_DEBUG 630 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 631 pmp, start, count, fillwith); 632#endif 633 /* 634 * Be sure the clusters are in the filesystem. 635 */ 636 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 637 return (EINVAL); 638 639 while (count > 0) { 640 byteoffset = FATOFS(pmp, start); 641 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 642 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 643 if (error) { 644 brelse(bp); 645 return (error); 646 } 647 while (count > 0) { 648 start++; 649 newc = --count > 0 ? start : fillwith; 650 switch (pmp->pm_fatmask) { 651 case FAT12_MASK: 652 readcn = getushort(&bp->b_data[bo]); 653 if (start & 1) { 654 readcn &= 0xf000; 655 readcn |= newc & 0xfff; 656 } else { 657 readcn &= 0x000f; 658 readcn |= newc << 4; 659 } 660 putushort(&bp->b_data[bo], readcn); 661 bo++; 662 if (!(start & 1)) 663 bo++; 664 break; 665 case FAT16_MASK: 666 putushort(&bp->b_data[bo], newc); 667 bo += 2; 668 break; 669 case FAT32_MASK: 670 readcn = getulong(&bp->b_data[bo]); 671 readcn &= ~pmp->pm_fatmask; 672 readcn |= newc & pmp->pm_fatmask; 673 putulong(&bp->b_data[bo], readcn); 674 bo += 4; 675 break; 676 } 677 if (bo >= bsize) 678 break; 679 } 680 updatefats(pmp, bp, bn); 681 } 682 pmp->pm_fmod = 1; 683 return (0); 684} 685 686/* 687 * Check the length of a free cluster chain starting at start. 688 * 689 * pmp - mount point 690 * start - start of chain 691 * count - maximum interesting length 692 */ 693static int 694chainlength(pmp, start, count) 695 struct msdosfsmount *pmp; 696 u_long start; 697 u_long count; 698{ 699 u_long idx, max_idx; 700 u_int map; 701 u_long len; 702 703 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 704 idx = start / N_INUSEBITS; 705 start %= N_INUSEBITS; 706 map = pmp->pm_inusemap[idx]; 707 map &= ~((1 << start) - 1); 708 if (map) { 709 len = ffs(map) - 1 - start; 710 return (len > count ? count : len); 711 } 712 len = N_INUSEBITS - start; 713 if (len >= count) 714 return (count); 715 while (++idx <= max_idx) { 716 if (len >= count) 717 break; 718 map = pmp->pm_inusemap[idx]; 719 if (map) { 720 len += ffs(map) - 1; 721 break; 722 } 723 len += N_INUSEBITS; 724 } 725 return (len > count ? count : len); 726} 727 728/* 729 * Allocate contigous free clusters. 730 * 731 * pmp - mount point. 732 * start - start of cluster chain. 733 * count - number of clusters to allocate. 734 * fillwith - put this value into the fat entry for the 735 * last allocated cluster. 736 * retcluster - put the first allocated cluster's number here. 737 * got - how many clusters were actually allocated. 738 */ 739static int 740chainalloc(pmp, start, count, fillwith, retcluster, got) 741 struct msdosfsmount *pmp; 742 u_long start; 743 u_long count; 744 u_long fillwith; 745 u_long *retcluster; 746 u_long *got; 747{ 748 int error; 749 u_long cl, n; 750 751 for (cl = start, n = count; n-- > 0;) 752 usemap_alloc(pmp, cl++); 753 754 error = fatchain(pmp, start, count, fillwith); 755 if (error != 0) 756 return (error); 757#ifdef MSDOSFS_DEBUG 758 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 759 start, count); 760#endif 761 if (retcluster) 762 *retcluster = start; 763 if (got) 764 *got = count; 765 pmp->pm_nxtfree = start + count; 766 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 767 pmp->pm_nxtfree = CLUST_FIRST; 768 return (0); 769} 770 771/* 772 * Allocate contiguous free clusters. 773 * 774 * pmp - mount point. 775 * start - preferred start of cluster chain. 776 * count - number of clusters requested. 777 * fillwith - put this value into the fat entry for the 778 * last allocated cluster. 779 * retcluster - put the first allocated cluster's number here. 780 * got - how many clusters were actually allocated. 781 */ 782int 783clusteralloc(pmp, start, count, fillwith, retcluster, got) 784 struct msdosfsmount *pmp; 785 u_long start; 786 u_long count; 787 u_long fillwith; 788 u_long *retcluster; 789 u_long *got; 790{ 791 u_long idx; 792 u_long len, newst, foundl, cn, l; 793 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 794 u_int map; 795 796#ifdef MSDOSFS_DEBUG 797 printf("clusteralloc(): find %lu clusters\n",count); 798#endif 799 if (start) { 800 if ((len = chainlength(pmp, start, count)) >= count) 801 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 802 } else 803 len = 0; 804 805 newst = pmp->pm_nxtfree; 806 foundl = 0; 807 808 for (cn = newst; cn <= pmp->pm_maxcluster;) { 809 idx = cn / N_INUSEBITS; 810 map = pmp->pm_inusemap[idx]; 811 map |= (1 << (cn % N_INUSEBITS)) - 1; 812 if (map != (u_int)-1) { 813 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 814 if ((l = chainlength(pmp, cn, count)) >= count) 815 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 816 if (l > foundl) { 817 foundcn = cn; 818 foundl = l; 819 } 820 cn += l + 1; 821 continue; 822 } 823 cn += N_INUSEBITS - cn % N_INUSEBITS; 824 } 825 for (cn = 0; cn < newst;) { 826 idx = cn / N_INUSEBITS; 827 map = pmp->pm_inusemap[idx]; 828 map |= (1 << (cn % N_INUSEBITS)) - 1; 829 if (map != (u_int)-1) { 830 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 831 if ((l = chainlength(pmp, cn, count)) >= count) 832 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 833 if (l > foundl) { 834 foundcn = cn; 835 foundl = l; 836 } 837 cn += l + 1; 838 continue; 839 } 840 cn += N_INUSEBITS - cn % N_INUSEBITS; 841 } 842 843 if (!foundl) 844 return (ENOSPC); 845 846 if (len) 847 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 848 else 849 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 850} 851 852 853/* 854 * Free a chain of clusters. 855 * 856 * pmp - address of the msdosfs mount structure for the filesystem 857 * containing the cluster chain to be freed. 858 * startcluster - number of the 1st cluster in the chain of clusters to be 859 * freed. 860 */ 861int 862freeclusterchain(pmp, cluster) 863 struct msdosfsmount *pmp; 864 u_long cluster; 865{ 866 int error; 867 struct buf *bp = NULL; 868 u_long bn, bo, bsize, byteoffset; 869 u_long readcn, lbn = -1; 870 871 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 872 byteoffset = FATOFS(pmp, cluster); 873 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 874 if (lbn != bn) { 875 if (bp) 876 updatefats(pmp, bp, lbn); 877 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 878 if (error) { 879 brelse(bp); 880 return (error); 881 } 882 lbn = bn; 883 } 884 usemap_free(pmp, cluster); 885 switch (pmp->pm_fatmask) { 886 case FAT12_MASK: 887 readcn = getushort(&bp->b_data[bo]); 888 if (cluster & 1) { 889 cluster = readcn >> 4; 890 readcn &= 0x000f; 891 readcn |= MSDOSFSFREE << 4; 892 } else { 893 cluster = readcn; 894 readcn &= 0xf000; 895 readcn |= MSDOSFSFREE & 0xfff; 896 } 897 putushort(&bp->b_data[bo], readcn); 898 break; 899 case FAT16_MASK: 900 cluster = getushort(&bp->b_data[bo]); 901 putushort(&bp->b_data[bo], MSDOSFSFREE); 902 break; 903 case FAT32_MASK: 904 cluster = getulong(&bp->b_data[bo]); 905 putulong(&bp->b_data[bo], 906 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 907 break; 908 } 909 cluster &= pmp->pm_fatmask; 910 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 911 cluster |= pmp->pm_fatmask; 912 } 913 if (bp) 914 updatefats(pmp, bp, bn); 915 return (0); 916} 917 918/* 919 * Read in fat blocks looking for free clusters. For every free cluster 920 * found turn off its corresponding bit in the pm_inusemap. 921 */ 922int 923fillinusemap(pmp) 924 struct msdosfsmount *pmp; 925{ 926 struct buf *bp = NULL; 927 u_long cn, readcn; 928 int error; 929 u_long bn, bo, bsize, byteoffset; 930 931 /* 932 * Mark all clusters in use, we mark the free ones in the fat scan 933 * loop further down. 934 */ 935 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 936 pmp->pm_inusemap[cn] = (u_int)-1; 937 938 /* 939 * Figure how many free clusters are in the filesystem by ripping 940 * through the fat counting the number of entries whose content is 941 * zero. These represent free clusters. 942 */ 943 pmp->pm_freeclustercount = 0; 944 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 945 byteoffset = FATOFS(pmp, cn); 946 bo = byteoffset % pmp->pm_fatblocksize; 947 if (!bo || !bp) { 948 /* Read new FAT block */ 949 if (bp) 950 brelse(bp); 951 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 952 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 953 if (error) { 954 brelse(bp); 955 return (error); 956 } 957 } 958 if (FAT32(pmp)) 959 readcn = getulong(&bp->b_data[bo]); 960 else 961 readcn = getushort(&bp->b_data[bo]); 962 if (FAT12(pmp) && (cn & 1)) 963 readcn >>= 4; 964 readcn &= pmp->pm_fatmask; 965 966 if (readcn == 0) 967 usemap_free(pmp, cn); 968 } 969 brelse(bp); 970 return (0); 971} 972 973/* 974 * Allocate a new cluster and chain it onto the end of the file. 975 * 976 * dep - the file to extend 977 * count - number of clusters to allocate 978 * bpp - where to return the address of the buf header for the first new 979 * file block 980 * ncp - where to put cluster number of the first newly allocated cluster 981 * If this pointer is 0, do not return the cluster number. 982 * flags - see fat.h 983 * 984 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 985 * the de_flag field of the denode and it does not change the de_FileSize 986 * field. This is left for the caller to do. 987 */ 988int 989extendfile(dep, count, bpp, ncp, flags) 990 struct denode *dep; 991 u_long count; 992 struct buf **bpp; 993 u_long *ncp; 994 int flags; 995{ 996 int error; 997 u_long frcn; 998 u_long cn, got; 999 struct msdosfsmount *pmp = dep->de_pmp; 1000 struct buf *bp; 1001 daddr_t blkno; 1002 1003 /* 1004 * Don't try to extend the root directory 1005 */ 1006 if (dep->de_StartCluster == MSDOSFSROOT 1007 && (dep->de_Attributes & ATTR_DIRECTORY)) { 1008 printf("extendfile(): attempt to extend root directory\n"); 1009 return (ENOSPC); 1010 } 1011 1012 /* 1013 * If the "file's last cluster" cache entry is empty, and the file 1014 * is not empty, then fill the cache entry by calling pcbmap(). 1015 */ 1016 fc_fileextends++; 1017 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 1018 dep->de_StartCluster != 0) { 1019 fc_lfcempty++; 1020 error = pcbmap(dep, 0xffff, 0, &cn, 0); 1021 /* we expect it to return E2BIG */ 1022 if (error != E2BIG) 1023 return (error); 1024 } 1025 1026 fc_last_to_nexttolast(dep); 1027 while (count > 0) { 1028 /* 1029 * Allocate a new cluster chain and cat onto the end of the 1030 * file. * If the file is empty we make de_StartCluster point 1031 * to the new block. Note that de_StartCluster being 0 is 1032 * sufficient to be sure the file is empty since we exclude 1033 * attempts to extend the root directory above, and the root 1034 * dir is the only file with a startcluster of 0 that has 1035 * blocks allocated (sort of). 1036 */ 1037 if (dep->de_StartCluster == 0) 1038 cn = 0; 1039 else 1040 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1041 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1042 if (error) 1043 return (error); 1044 1045 count -= got; 1046 1047 /* 1048 * Give them the filesystem relative cluster number if they want 1049 * it. 1050 */ 1051 if (ncp) { 1052 *ncp = cn; 1053 ncp = NULL; 1054 } 1055 1056 if (dep->de_StartCluster == 0) { 1057 dep->de_StartCluster = cn; 1058 frcn = 0; 1059 } else { 1060 error = fatentry(FAT_SET, pmp, 1061 dep->de_fc[FC_LASTFC].fc_fsrcn, 1062 0, cn); 1063 if (error) { 1064 clusterfree(pmp, cn, NULL); 1065 return (error); 1066 } 1067 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1068 } 1069 1070 /* 1071 * Update the "last cluster of the file" entry in the denode's fat 1072 * cache. 1073 */ 1074 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1075 1076 if (flags & DE_CLEAR) { 1077 while (got-- > 0) { 1078 /* 1079 * Get the buf header for the new block of the file. 1080 */ 1081 if (dep->de_Attributes & ATTR_DIRECTORY) 1082 bp = getblk(pmp->pm_devvp, 1083 cntobn(pmp, cn++), 1084 pmp->pm_bpcluster, 0, 0, 0); 1085 else { 1086 bp = getblk(DETOV(dep), 1087 de_cn2bn(pmp, frcn++), 1088 pmp->pm_bpcluster, 0, 0, 0); 1089 /* 1090 * Do the bmap now, as in msdosfs_write 1091 */ 1092 if (pcbmap(dep, 1093 de_bn2cn(pmp, bp->b_lblkno), 1094 &blkno, 0, 0)) 1095 bp->b_blkno = -1; 1096 if (bp->b_blkno == -1) 1097 panic("extendfile: pcbmap"); 1098 else 1099 bp->b_blkno = blkno; 1100 } 1101 vfs_bio_clrbuf(bp); 1102 if (bpp) { 1103 *bpp = bp; 1104 bpp = NULL; 1105 } else 1106 bdwrite(bp); 1107 } 1108 } 1109 } 1110 1111 return (0); 1112} 1113 1114/*- 1115 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1116 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1117 * this bit is not defined for FAT12 volumes, which are always assumed to 1118 * be dirty. 1119 * 1120 * The fatentry() routine only works on cluster numbers that a file could 1121 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1122 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1123 * 1124 * Inputs: 1125 * pmp The MS-DOS volume to mark 1126 * dirty Non-zero if the volume should be marked dirty; zero if it 1127 * should be marked clean 1128 * 1129 * Result: 1130 * 0 Success 1131 * EROFS Volume is read-only 1132 * ? (other errors from called routines) 1133 */ 1134int 1135markvoldirty(struct msdosfsmount *pmp, int dirty) 1136{ 1137 struct buf *bp; 1138 u_long bn, bo, bsize, byteoffset, fatval; 1139 int error; 1140 1141 /* 1142 * FAT12 does not support a "clean" bit, so don't do anything for 1143 * FAT12. 1144 */ 1145 if (FAT12(pmp)) 1146 return (0); 1147 1148 /* Can't change the bit on a read-only filesystem. */ 1149 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1150 return (EROFS); 1151 1152 /* 1153 * Fetch the block containing the FAT entry. It is given by the 1154 * pseudo-cluster 1. 1155 */ 1156 byteoffset = FATOFS(pmp, 1); 1157 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1158 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1159 if (error) { 1160 brelse(bp); 1161 return (error); 1162 } 1163 1164 /* 1165 * Get the current value of the FAT entry and set/clear the relevant 1166 * bit. Dirty means clear the "clean" bit; clean means set the 1167 * "clean" bit. 1168 */ 1169 if (FAT32(pmp)) { 1170 /* FAT32 uses bit 27. */ 1171 fatval = getulong(&bp->b_data[bo]); 1172 if (dirty) 1173 fatval &= 0xF7FFFFFF; 1174 else 1175 fatval |= 0x08000000; 1176 putulong(&bp->b_data[bo], fatval); 1177 } else { 1178 /* Must be FAT16; use bit 15. */ 1179 fatval = getushort(&bp->b_data[bo]); 1180 if (dirty) 1181 fatval &= 0x7FFF; 1182 else 1183 fatval |= 0x8000; 1184 putushort(&bp->b_data[bo], fatval); 1185 } 1186 1187 /* Write out the modified FAT block synchronously. */ 1188 return (bwrite(bp)); 1189} 1190