1 /* $NetBSD: msdosfs_fat.c,v 1.11 2006/09/22 17:45:21 xtraeme Exp $ */ 2 3 /*- 4 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank. 5 * Copyright (C) 1994, 1995, 1997 TooLs GmbH. 6 * All rights reserved. 7 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below). 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by TooLs GmbH. 20 * 4. The name of TooLs GmbH may not be used to endorse or promote products 21 * derived from this software without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 27 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 28 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 29 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 30 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 31 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 32 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 */ 34 /* 35 * Written by Paul Popelka (paulp@uts.amdahl.com) 36 * 37 * You can do anything you want with this software, just don't say you wrote 38 * it, and don't remove this notice. 39 * 40 * This software is provided "as is". 41 * 42 * The author supplies this software to be publicly redistributed on the 43 * understanding that the author is not responsible for the correct 44 * functioning of this software in any circumstances and is not liable for 45 * any damages caused by this software. 46 * 47 * October 1992 48 */ 49 50 #include <sys/cdefs.h> 51 __KERNEL_RCSID(0, "$NetBSD: msdosfs_fat.c,v 1.11 2006/09/22 17:45:21 xtraeme Exp $"); 52 53 /* 54 * kernel include files. 55 */ 56 #include <sys/param.h> 57 #include <sys/systm.h> 58 #include <sys/buf.h> 59 #include <sys/file.h> 60 #include <sys/namei.h> 61 #include <sys/mount.h> /* to define statvfs structure */ 62 #include <sys/vnode.h> /* to define vattr structure */ 63 #include <sys/errno.h> 64 #include <sys/dirent.h> 65 #include <sys/kauth.h> 66 67 /* 68 * msdosfs include files. 69 */ 70 #include <fs/msdosfs/bpb.h> 71 #include <fs/msdosfs/msdosfsmount.h> 72 #include <fs/msdosfs/direntry.h> 73 #include <fs/msdosfs/denode.h> 74 #include <fs/msdosfs/fat.h> 75 76 /* 77 * Fat cache stats. 78 */ 79 int fc_fileextends; /* # of file extends */ 80 int fc_lfcempty; /* # of time last file cluster cache entry 81 * was empty */ 82 int fc_bmapcalls; /* # of times pcbmap was called */ 83 84 #define LMMAX 20 85 int fc_lmdistance[LMMAX]; /* counters for how far off the last 86 * cluster mapped entry was. */ 87 int fc_largedistance; /* off by more than LMMAX */ 88 int fc_wherefrom, fc_whereto, fc_lastclust; 89 int pm_fatblocksize; 90 91 #ifdef MSDOSFS_DEBUG 92 void print_fat_stats(void); 93 94 void 95 print_fat_stats(void) 96 { 97 int i; 98 99 printf("fc_fileextends=%d fc_lfcempty=%d fc_bmapcalls=%d " 100 "fc_largedistance=%d [%d->%d=%d] fc_lastclust=%d pm_fatblocksize=%d\n", 101 fc_fileextends, fc_lfcempty, fc_bmapcalls, fc_largedistance, 102 fc_wherefrom, fc_whereto, fc_whereto-fc_wherefrom, 103 fc_lastclust, pm_fatblocksize); 104 105 fc_fileextends = fc_lfcempty = fc_bmapcalls = 0; 106 fc_wherefrom = fc_whereto = fc_lastclust = 0; 107 108 for (i = 0; i < LMMAX; i++) { 109 printf("%d:%d ", i, fc_lmdistance[i]); 110 fc_lmdistance[i] = 0; 111 } 112 113 printf("\n"); 114 } 115 #endif 116 117 static void fatblock(struct msdosfsmount *, u_long, u_long *, u_long *, 118 u_long *); 119 void updatefats(struct msdosfsmount *, struct buf *, u_long); 120 static inline void usemap_free(struct msdosfsmount *, u_long); 121 static inline void usemap_alloc(struct msdosfsmount *, u_long); 122 static int fatchain(struct msdosfsmount *, u_long, u_long, u_long); 123 int chainlength(struct msdosfsmount *, u_long, u_long); 124 int chainalloc(struct msdosfsmount *, u_long, u_long, u_long, u_long *, 125 u_long *); 126 127 static void 128 fatblock(pmp, ofs, bnp, sizep, bop) 129 struct msdosfsmount *pmp; 130 u_long ofs; 131 u_long *bnp; 132 u_long *sizep; 133 u_long *bop; 134 { 135 u_long bn, size; 136 137 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 138 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 139 * pmp->pm_BytesPerSec; 140 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 141 142 if (bnp) 143 *bnp = bn; 144 if (sizep) 145 *sizep = size; 146 if (bop) 147 *bop = ofs % pmp->pm_fatblocksize; 148 149 pm_fatblocksize = pmp->pm_fatblocksize; 150 } 151 152 /* 153 * Map the logical cluster number of a file into a physical disk sector 154 * that is filesystem relative. 155 * 156 * dep - address of denode representing the file of interest 157 * findcn - file relative cluster whose filesystem relative cluster number 158 * and/or block number are/is to be found 159 * bnp - address of where to place the file system relative block number. 160 * If this pointer is null then don't return this quantity. 161 * cnp - address of where to place the file system relative cluster number. 162 * If this pointer is null then don't return this quantity. 163 * 164 * NOTE: Either bnp or cnp must be non-null. 165 * This function has one side effect. If the requested file relative cluster 166 * is beyond the end of file, then the actual number of clusters in the file 167 * is returned in *cnp. This is useful for determining how long a directory is. 168 * If cnp is null, nothing is returned. 169 */ 170 int 171 pcbmap(dep, findcn, bnp, cnp, sp) 172 struct denode *dep; 173 u_long findcn; /* file relative cluster to get */ 174 daddr_t *bnp; /* returned filesys relative blk number */ 175 u_long *cnp; /* returned cluster number */ 176 int *sp; /* returned block size */ 177 { 178 int error; 179 u_long i; 180 u_long cn; 181 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 182 u_long byteoffset; 183 u_long bn; 184 u_long bo; 185 struct buf *bp = NULL; 186 u_long bp_bn = -1; 187 struct msdosfsmount *pmp = dep->de_pmp; 188 u_long bsize; 189 190 fc_bmapcalls++; 191 192 /* 193 * If they don't give us someplace to return a value then don't 194 * bother doing anything. 195 */ 196 if (bnp == NULL && cnp == NULL && sp == NULL) 197 return (0); 198 199 cn = dep->de_StartCluster; 200 /* 201 * The "file" that makes up the root directory is contiguous, 202 * permanently allocated, of fixed size, and is not made up of 203 * clusters. If the cluster number is beyond the end of the root 204 * directory, then return the number of clusters in the file. 205 */ 206 if (cn == MSDOSFSROOT) { 207 if (dep->de_Attributes & ATTR_DIRECTORY) { 208 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 209 if (cnp) 210 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 211 return (E2BIG); 212 } 213 if (bnp) 214 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 215 if (cnp) 216 *cnp = MSDOSFSROOT; 217 if (sp) 218 *sp = min(pmp->pm_bpcluster, 219 dep->de_FileSize - de_cn2off(pmp, findcn)); 220 return (0); 221 } else { /* just an empty file */ 222 if (cnp) 223 *cnp = 0; 224 return (E2BIG); 225 } 226 } 227 228 /* 229 * All other files do I/O in cluster sized blocks 230 */ 231 if (sp) 232 *sp = pmp->pm_bpcluster; 233 234 /* 235 * Rummage around in the fat cache, maybe we can avoid tromping 236 * thru every fat entry for the file. And, keep track of how far 237 * off the cache was from where we wanted to be. 238 */ 239 i = 0; 240 fc_lookup(dep, findcn, &i, &cn); 241 if ((bn = findcn - i) >= LMMAX) { 242 fc_largedistance++; 243 fc_wherefrom = i; 244 fc_whereto = findcn; 245 fc_lastclust = dep->de_fc[FC_LASTFC].fc_frcn; 246 } else 247 fc_lmdistance[bn]++; 248 249 /* 250 * Handle all other files or directories the normal way. 251 */ 252 for (; i < findcn; i++) { 253 /* 254 * Stop with all reserved clusters, not just with EOF. 255 */ 256 if (cn >= (CLUST_RSRVD & pmp->pm_fatmask)) 257 goto hiteof; 258 byteoffset = FATOFS(pmp, cn); 259 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 260 if (bn != bp_bn) { 261 if (bp) 262 brelse(bp); 263 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 264 if (error) { 265 brelse(bp); 266 return (error); 267 } 268 bp_bn = bn; 269 } 270 prevcn = cn; 271 if (bo >= bsize) { 272 if (bp) 273 brelse(bp); 274 return (EIO); 275 } 276 KASSERT(bp != NULL); 277 if (FAT32(pmp)) 278 cn = getulong(&bp->b_data[bo]); 279 else 280 cn = getushort(&bp->b_data[bo]); 281 if (FAT12(pmp) && (prevcn & 1)) 282 cn >>= 4; 283 cn &= pmp->pm_fatmask; 284 } 285 286 if (!MSDOSFSEOF(cn, pmp->pm_fatmask)) { 287 if (bp) 288 brelse(bp); 289 if (bnp) 290 *bnp = cntobn(pmp, cn); 291 if (cnp) 292 *cnp = cn; 293 fc_setcache(dep, FC_LASTMAP, i, cn); 294 return (0); 295 } 296 297 hiteof:; 298 if (cnp) 299 *cnp = i; 300 if (bp) 301 brelse(bp); 302 /* update last file cluster entry in the fat cache */ 303 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 304 return (E2BIG); 305 } 306 307 /* 308 * Find the closest entry in the fat cache to the cluster we are looking 309 * for. 310 */ 311 void 312 fc_lookup(dep, findcn, frcnp, fsrcnp) 313 struct denode *dep; 314 u_long findcn; 315 u_long *frcnp; 316 u_long *fsrcnp; 317 { 318 int i; 319 u_long cn; 320 struct fatcache *closest = 0; 321 322 for (i = 0; i < FC_SIZE; i++) { 323 cn = dep->de_fc[i].fc_frcn; 324 if (cn != FCE_EMPTY && cn <= findcn) { 325 if (closest == 0 || cn > closest->fc_frcn) 326 closest = &dep->de_fc[i]; 327 } 328 } 329 if (closest) { 330 *frcnp = closest->fc_frcn; 331 *fsrcnp = closest->fc_fsrcn; 332 } 333 } 334 335 /* 336 * Purge the fat cache in denode dep of all entries relating to file 337 * relative cluster frcn and beyond. 338 */ 339 void 340 fc_purge(dep, frcn) 341 struct denode *dep; 342 u_int frcn; 343 { 344 int i; 345 struct fatcache *fcp; 346 347 fcp = dep->de_fc; 348 for (i = 0; i < FC_SIZE; i++, fcp++) { 349 if (fcp->fc_frcn >= frcn) 350 fcp->fc_frcn = FCE_EMPTY; 351 } 352 } 353 354 /* 355 * Update the fat. 356 * If mirroring the fat, update all copies, with the first copy as last. 357 * Else update only the current fat (ignoring the others). 358 * 359 * pmp - msdosfsmount structure for filesystem to update 360 * bp - addr of modified fat block 361 * fatbn - block number relative to begin of filesystem of the modified fat block. 362 */ 363 void 364 updatefats(pmp, bp, fatbn) 365 struct msdosfsmount *pmp; 366 struct buf *bp; 367 u_long fatbn; 368 { 369 int i; 370 struct buf *bpn; 371 372 #ifdef MSDOSFS_DEBUG 373 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", 374 pmp, bp, fatbn); 375 #endif 376 377 /* 378 * If we have an FSInfo block, update it. 379 */ 380 if (pmp->pm_fsinfo) { 381 u_long cn = pmp->pm_nxtfree; 382 383 if (pmp->pm_freeclustercount 384 && (pmp->pm_inusemap[cn / N_INUSEBITS] 385 & (1 << (cn % N_INUSEBITS)))) { 386 /* 387 * The cluster indicated in FSInfo isn't free 388 * any longer. Got get a new free one. 389 */ 390 for (cn = 0; cn < pmp->pm_maxcluster; cn++) 391 if (pmp->pm_inusemap[cn / N_INUSEBITS] != (u_int)-1) 392 break; 393 pmp->pm_nxtfree = cn 394 + ffs(pmp->pm_inusemap[cn / N_INUSEBITS] 395 ^ (u_int)-1) - 1; 396 } 397 if (bread(pmp->pm_devvp, pmp->pm_fsinfo, 1024, NOCRED, &bpn) != 0) { 398 /* 399 * Ignore the error, but turn off FSInfo update for the future. 400 */ 401 pmp->pm_fsinfo = 0; 402 brelse(bpn); 403 } else { 404 struct fsinfo *fp = (struct fsinfo *)bpn->b_data; 405 406 putulong(fp->fsinfree, pmp->pm_freeclustercount); 407 putulong(fp->fsinxtfree, pmp->pm_nxtfree); 408 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 409 bwrite(bpn); 410 else 411 bdwrite(bpn); 412 } 413 } 414 415 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 416 /* 417 * Now copy the block(s) of the modified fat to the other copies of 418 * the fat and write them out. This is faster than reading in the 419 * other fats and then writing them back out. This could tie up 420 * the fat for quite a while. Preventing others from accessing it. 421 * To prevent us from going after the fat quite so much we use 422 * delayed writes, unless they specfied "synchronous" when the 423 * filesystem was mounted. If synch is asked for then use 424 * bwrite()'s and really slow things down. 425 */ 426 for (i = 1; i < pmp->pm_FATs; i++) { 427 fatbn += pmp->pm_FATsecs; 428 /* getblk() never fails */ 429 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 0, 0); 430 memcpy(bpn->b_data, bp->b_data, bp->b_bcount); 431 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 432 bwrite(bpn); 433 else 434 bdwrite(bpn); 435 } 436 } 437 438 /* 439 * Write out the first (or current) fat last. 440 */ 441 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 442 bwrite(bp); 443 else 444 bdwrite(bp); 445 /* 446 * Maybe update fsinfo sector here? 447 */ 448 } 449 450 /* 451 * Updating entries in 12 bit fats is a pain in the butt. 452 * 453 * The following picture shows where nibbles go when moving from a 12 bit 454 * cluster number into the appropriate bytes in the FAT. 455 * 456 * byte m byte m+1 byte m+2 457 * +----+----+ +----+----+ +----+----+ 458 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 459 * +----+----+ +----+----+ +----+----+ 460 * 461 * +----+----+----+ +----+----+----+ 462 * | 3 0 1 | | 4 5 2 | 463 * +----+----+----+ +----+----+----+ 464 * cluster n cluster n+1 465 * 466 * Where n is even. m = n + (n >> 2) 467 * 468 */ 469 static inline void 470 usemap_alloc(pmp, cn) 471 struct msdosfsmount *pmp; 472 u_long cn; 473 { 474 475 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 476 pmp->pm_freeclustercount--; 477 } 478 479 static inline void 480 usemap_free(pmp, cn) 481 struct msdosfsmount *pmp; 482 u_long cn; 483 { 484 485 pmp->pm_freeclustercount++; 486 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 487 } 488 489 int 490 clusterfree(pmp, cluster, oldcnp) 491 struct msdosfsmount *pmp; 492 u_long cluster; 493 u_long *oldcnp; 494 { 495 int error; 496 u_long oldcn; 497 498 usemap_free(pmp, cluster); 499 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 500 if (error) { 501 usemap_alloc(pmp, cluster); 502 return (error); 503 } 504 /* 505 * If the cluster was successfully marked free, then update 506 * the count of free clusters, and turn off the "allocated" 507 * bit in the "in use" cluster bit map. 508 */ 509 if (oldcnp) 510 *oldcnp = oldcn; 511 return (0); 512 } 513 514 /* 515 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 516 * 517 * function - whether to get or set a fat entry 518 * pmp - address of the msdosfsmount structure for the filesystem 519 * whose fat is to be manipulated. 520 * cn - which cluster is of interest 521 * oldcontents - address of a word that is to receive the contents of the 522 * cluster'th entry if this is a get function 523 * newcontents - the new value to be written into the cluster'th element of 524 * the fat if this is a set function. 525 * 526 * This function can also be used to free a cluster by setting the fat entry 527 * for a cluster to 0. 528 * 529 * All copies of the fat are updated if this is a set function. NOTE: If 530 * fatentry() marks a cluster as free it does not update the inusemap in 531 * the msdosfsmount structure. This is left to the caller. 532 */ 533 int 534 fatentry(function, pmp, cn, oldcontents, newcontents) 535 int function; 536 struct msdosfsmount *pmp; 537 u_long cn; 538 u_long *oldcontents; 539 u_long newcontents; 540 { 541 int error; 542 u_long readcn; 543 u_long bn, bo, bsize, byteoffset; 544 struct buf *bp; 545 546 #ifdef MSDOSFS_DEBUG 547 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 548 function, pmp, cn, oldcontents, newcontents); 549 #endif 550 551 #ifdef DIAGNOSTIC 552 /* 553 * Be sure they asked us to do something. 554 */ 555 if ((function & (FAT_SET | FAT_GET)) == 0) { 556 printf("fatentry(): function code doesn't specify get or set\n"); 557 return (EINVAL); 558 } 559 560 /* 561 * If they asked us to return a cluster number but didn't tell us 562 * where to put it, give them an error. 563 */ 564 if ((function & FAT_GET) && oldcontents == NULL) { 565 printf("fatentry(): get function with no place to put result\n"); 566 return (EINVAL); 567 } 568 #endif 569 570 /* 571 * Be sure the requested cluster is in the filesystem. 572 */ 573 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 574 return (EINVAL); 575 576 byteoffset = FATOFS(pmp, cn); 577 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 578 if ((error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp)) != 0) { 579 brelse(bp); 580 return (error); 581 } 582 583 if (function & FAT_GET) { 584 if (FAT32(pmp)) 585 readcn = getulong(&bp->b_data[bo]); 586 else 587 readcn = getushort(&bp->b_data[bo]); 588 if (FAT12(pmp) & (cn & 1)) 589 readcn >>= 4; 590 readcn &= pmp->pm_fatmask; 591 *oldcontents = readcn; 592 } 593 if (function & FAT_SET) { 594 switch (pmp->pm_fatmask) { 595 case FAT12_MASK: 596 readcn = getushort(&bp->b_data[bo]); 597 if (cn & 1) { 598 readcn &= 0x000f; 599 readcn |= newcontents << 4; 600 } else { 601 readcn &= 0xf000; 602 readcn |= newcontents & 0xfff; 603 } 604 putushort(&bp->b_data[bo], readcn); 605 break; 606 case FAT16_MASK: 607 putushort(&bp->b_data[bo], newcontents); 608 break; 609 case FAT32_MASK: 610 /* 611 * According to spec we have to retain the 612 * high order bits of the fat entry. 613 */ 614 readcn = getulong(&bp->b_data[bo]); 615 readcn &= ~FAT32_MASK; 616 readcn |= newcontents & FAT32_MASK; 617 putulong(&bp->b_data[bo], readcn); 618 break; 619 } 620 updatefats(pmp, bp, bn); 621 bp = NULL; 622 pmp->pm_fmod = 1; 623 } 624 if (bp) 625 brelse(bp); 626 return (0); 627 } 628 629 /* 630 * Update a contiguous cluster chain 631 * 632 * pmp - mount point 633 * start - first cluster of chain 634 * count - number of clusters in chain 635 * fillwith - what to write into fat entry of last cluster 636 */ 637 static int 638 fatchain(pmp, start, count, fillwith) 639 struct msdosfsmount *pmp; 640 u_long start; 641 u_long count; 642 u_long fillwith; 643 { 644 int error; 645 u_long bn, bo, bsize, byteoffset, readcn, newc; 646 struct buf *bp; 647 648 #ifdef MSDOSFS_DEBUG 649 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 650 pmp, start, count, fillwith); 651 #endif 652 /* 653 * Be sure the clusters are in the filesystem. 654 */ 655 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 656 return (EINVAL); 657 658 while (count > 0) { 659 byteoffset = FATOFS(pmp, start); 660 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 661 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 662 if (error) { 663 brelse(bp); 664 return (error); 665 } 666 while (count > 0) { 667 start++; 668 newc = --count > 0 ? start : fillwith; 669 switch (pmp->pm_fatmask) { 670 case FAT12_MASK: 671 readcn = getushort(&bp->b_data[bo]); 672 if (start & 1) { 673 readcn &= 0xf000; 674 readcn |= newc & 0xfff; 675 } else { 676 readcn &= 0x000f; 677 readcn |= newc << 4; 678 } 679 putushort(&bp->b_data[bo], readcn); 680 bo++; 681 if (!(start & 1)) 682 bo++; 683 break; 684 case FAT16_MASK: 685 putushort(&bp->b_data[bo], newc); 686 bo += 2; 687 break; 688 case FAT32_MASK: 689 readcn = getulong(&bp->b_data[bo]); 690 readcn &= ~pmp->pm_fatmask; 691 readcn |= newc & pmp->pm_fatmask; 692 putulong(&bp->b_data[bo], readcn); 693 bo += 4; 694 break; 695 } 696 if (bo >= bsize) 697 break; 698 } 699 updatefats(pmp, bp, bn); 700 } 701 pmp->pm_fmod = 1; 702 return (0); 703 } 704 705 /* 706 * Check the length of a free cluster chain starting at start. 707 * 708 * pmp - mount point 709 * start - start of chain 710 * count - maximum interesting length 711 */ 712 int 713 chainlength(pmp, start, count) 714 struct msdosfsmount *pmp; 715 u_long start; 716 u_long count; 717 { 718 u_long idx, max_idx; 719 u_int map; 720 u_long len; 721 722 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 723 idx = start / N_INUSEBITS; 724 start %= N_INUSEBITS; 725 map = pmp->pm_inusemap[idx]; 726 map &= ~((1 << start) - 1); 727 if (map) { 728 len = ffs(map) - 1 - start; 729 return (len > count ? count : len); 730 } 731 len = N_INUSEBITS - start; 732 if (len >= count) 733 return (count); 734 while (++idx <= max_idx) { 735 if (len >= count) 736 break; 737 if ((map = pmp->pm_inusemap[idx]) != 0) { 738 len += ffs(map) - 1; 739 break; 740 } 741 len += N_INUSEBITS; 742 } 743 return (len > count ? count : len); 744 } 745 746 /* 747 * Allocate contigous free clusters. 748 * 749 * pmp - mount point. 750 * start - start of cluster chain. 751 * count - number of clusters to allocate. 752 * fillwith - put this value into the fat entry for the 753 * last allocated cluster. 754 * retcluster - put the first allocated cluster's number here. 755 * got - how many clusters were actually allocated. 756 */ 757 int 758 chainalloc(pmp, start, count, fillwith, retcluster, got) 759 struct msdosfsmount *pmp; 760 u_long start; 761 u_long count; 762 u_long fillwith; 763 u_long *retcluster; 764 u_long *got; 765 { 766 int error; 767 u_long cl, n; 768 769 for (cl = start, n = count; n-- > 0;) 770 usemap_alloc(pmp, cl++); 771 if ((error = fatchain(pmp, start, count, fillwith)) != 0) 772 return (error); 773 #ifdef MSDOSFS_DEBUG 774 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 775 start, count); 776 #endif 777 if (retcluster) 778 *retcluster = start; 779 if (got) 780 *got = count; 781 return (0); 782 } 783 784 /* 785 * Allocate contiguous free clusters. 786 * 787 * pmp - mount point. 788 * start - preferred start of cluster chain. 789 * count - number of clusters requested. 790 * fillwith - put this value into the fat entry for the 791 * last allocated cluster. 792 * retcluster - put the first allocated cluster's number here. 793 * got - how many clusters were actually allocated. 794 */ 795 int 796 clusteralloc(pmp, start, count, retcluster, got) 797 struct msdosfsmount *pmp; 798 u_long start; 799 u_long count; 800 u_long *retcluster; 801 u_long *got; 802 { 803 u_long idx; 804 u_long len, newst, foundl, cn, l; 805 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 806 u_long fillwith = CLUST_EOFE; 807 u_int map; 808 809 #ifdef MSDOSFS_DEBUG 810 printf("clusteralloc(): find %lu clusters\n",count); 811 #endif 812 if (start) { 813 if ((len = chainlength(pmp, start, count)) >= count) 814 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 815 } else { 816 /* 817 * This is a new file, initialize start 818 */ 819 struct timeval tv; 820 821 microtime(&tv); 822 start = (tv.tv_usec >> 10) | tv.tv_usec; 823 len = 0; 824 } 825 826 /* 827 * Start at a (pseudo) random place to maximize cluster runs 828 * under multiple writers. 829 */ 830 newst = (start * 1103515245 + 12345) % (pmp->pm_maxcluster + 1); 831 foundl = 0; 832 833 for (cn = newst; cn <= pmp->pm_maxcluster;) { 834 idx = cn / N_INUSEBITS; 835 map = pmp->pm_inusemap[idx]; 836 map |= (1 << (cn % N_INUSEBITS)) - 1; 837 if (map != (u_int)-1) { 838 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 839 if ((l = chainlength(pmp, cn, count)) >= count) 840 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 841 if (l > foundl) { 842 foundcn = cn; 843 foundl = l; 844 } 845 cn += l + 1; 846 continue; 847 } 848 cn += N_INUSEBITS - cn % N_INUSEBITS; 849 } 850 for (cn = 0; cn < newst;) { 851 idx = cn / N_INUSEBITS; 852 map = pmp->pm_inusemap[idx]; 853 map |= (1 << (cn % N_INUSEBITS)) - 1; 854 if (map != (u_int)-1) { 855 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 856 if ((l = chainlength(pmp, cn, count)) >= count) 857 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 858 if (l > foundl) { 859 foundcn = cn; 860 foundl = l; 861 } 862 cn += l + 1; 863 continue; 864 } 865 cn += N_INUSEBITS - cn % N_INUSEBITS; 866 } 867 868 if (!foundl) 869 return (ENOSPC); 870 871 if (len) 872 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 873 else 874 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 875 } 876 877 878 /* 879 * Free a chain of clusters. 880 * 881 * pmp - address of the msdosfs mount structure for the filesystem 882 * containing the cluster chain to be freed. 883 * startcluster - number of the 1st cluster in the chain of clusters to be 884 * freed. 885 */ 886 int 887 freeclusterchain(pmp, cluster) 888 struct msdosfsmount *pmp; 889 u_long cluster; 890 { 891 int error; 892 struct buf *bp = NULL; 893 u_long bn, bo, bsize, byteoffset; 894 u_long readcn, lbn = -1; 895 896 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 897 byteoffset = FATOFS(pmp, cluster); 898 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 899 if (lbn != bn) { 900 if (bp) 901 updatefats(pmp, bp, lbn); 902 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 903 if (error) { 904 brelse(bp); 905 return (error); 906 } 907 lbn = bn; 908 } 909 usemap_free(pmp, cluster); 910 KASSERT(bp != NULL); 911 switch (pmp->pm_fatmask) { 912 case FAT12_MASK: 913 readcn = getushort(&bp->b_data[bo]); 914 if (cluster & 1) { 915 cluster = readcn >> 4; 916 readcn &= 0x000f; 917 readcn |= MSDOSFSFREE << 4; 918 } else { 919 cluster = readcn; 920 readcn &= 0xf000; 921 readcn |= MSDOSFSFREE & 0xfff; 922 } 923 putushort(&bp->b_data[bo], readcn); 924 break; 925 case FAT16_MASK: 926 cluster = getushort(&bp->b_data[bo]); 927 putushort(&bp->b_data[bo], MSDOSFSFREE); 928 break; 929 case FAT32_MASK: 930 cluster = getulong(&bp->b_data[bo]); 931 putulong(&bp->b_data[bo], 932 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 933 break; 934 } 935 cluster &= pmp->pm_fatmask; 936 } 937 if (bp) 938 updatefats(pmp, bp, bn); 939 return (0); 940 } 941 942 /* 943 * Read in fat blocks looking for free clusters. For every free cluster 944 * found turn off its corresponding bit in the pm_inusemap. 945 */ 946 int 947 fillinusemap(pmp) 948 struct msdosfsmount *pmp; 949 { 950 struct buf *bp = NULL; 951 u_long cn, readcn; 952 int error; 953 u_long bn, bo, bsize, byteoffset; 954 955 /* 956 * Mark all clusters in use, we mark the free ones in the fat scan 957 * loop further down. 958 */ 959 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 960 pmp->pm_inusemap[cn] = (u_int)-1; 961 962 /* 963 * Figure how many free clusters are in the filesystem by ripping 964 * through the fat counting the number of entries whose content is 965 * zero. These represent free clusters. 966 */ 967 pmp->pm_freeclustercount = 0; 968 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 969 byteoffset = FATOFS(pmp, cn); 970 bo = byteoffset % pmp->pm_fatblocksize; 971 if (!bo || !bp) { 972 /* Read new FAT block */ 973 if (bp) 974 brelse(bp); 975 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 976 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 977 if (error) { 978 brelse(bp); 979 return (error); 980 } 981 } 982 if (FAT32(pmp)) 983 readcn = getulong(&bp->b_data[bo]); 984 else 985 readcn = getushort(&bp->b_data[bo]); 986 if (FAT12(pmp) && (cn & 1)) 987 readcn >>= 4; 988 readcn &= pmp->pm_fatmask; 989 990 if (readcn == 0) 991 usemap_free(pmp, cn); 992 } 993 brelse(bp); 994 return (0); 995 } 996 997 /* 998 * Allocate a new cluster and chain it onto the end of the file. 999 * 1000 * dep - the file to extend 1001 * count - number of clusters to allocate 1002 * bpp - where to return the address of the buf header for the first new 1003 * file block 1004 * ncp - where to put cluster number of the first newly allocated cluster 1005 * If this pointer is 0, do not return the cluster number. 1006 * flags - see fat.h 1007 * 1008 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 1009 * the de_flag field of the denode and it does not change the de_FileSize 1010 * field. This is left for the caller to do. 1011 */ 1012 1013 int 1014 extendfile(dep, count, bpp, ncp, flags) 1015 struct denode *dep; 1016 u_long count; 1017 struct buf **bpp; 1018 u_long *ncp; 1019 int flags; 1020 { 1021 int error; 1022 u_long frcn = 0, cn, got; 1023 struct msdosfsmount *pmp = dep->de_pmp; 1024 struct buf *bp; 1025 1026 /* 1027 * Don't try to extend the root directory 1028 */ 1029 if (dep->de_StartCluster == MSDOSFSROOT 1030 && (dep->de_Attributes & ATTR_DIRECTORY)) { 1031 printf("extendfile(): attempt to extend root directory\n"); 1032 return (ENOSPC); 1033 } 1034 1035 /* 1036 * If the "file's last cluster" cache entry is empty, and the file 1037 * is not empty, then fill the cache entry by calling pcbmap(). 1038 */ 1039 fc_fileextends++; 1040 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 1041 dep->de_StartCluster != 0) { 1042 fc_lfcempty++; 1043 error = pcbmap(dep, CLUST_END, 0, &cn, 0); 1044 /* we expect it to return E2BIG */ 1045 if (error != E2BIG) 1046 return (error); 1047 } 1048 1049 fc_last_to_nexttolast(dep); 1050 1051 while (count > 0) { 1052 1053 /* 1054 * Allocate a new cluster chain and cat onto the end of the 1055 * file. If the file is empty we make de_StartCluster point 1056 * to the new block. Note that de_StartCluster being 0 is 1057 * sufficient to be sure the file is empty since we exclude 1058 * attempts to extend the root directory above, and the root 1059 * dir is the only file with a startcluster of 0 that has 1060 * blocks allocated (sort of). 1061 */ 1062 1063 if (dep->de_StartCluster == 0) 1064 cn = 0; 1065 else 1066 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1067 error = clusteralloc(pmp, cn, count, &cn, &got); 1068 if (error) 1069 return (error); 1070 1071 count -= got; 1072 1073 /* 1074 * Give them the filesystem relative cluster number if they want 1075 * it. 1076 */ 1077 if (ncp) { 1078 *ncp = cn; 1079 ncp = NULL; 1080 } 1081 1082 if (dep->de_StartCluster == 0) { 1083 dep->de_StartCluster = cn; 1084 frcn = 0; 1085 } else { 1086 error = fatentry(FAT_SET, pmp, 1087 dep->de_fc[FC_LASTFC].fc_fsrcn, 1088 0, cn); 1089 if (error) { 1090 clusterfree(pmp, cn, NULL); 1091 return (error); 1092 } 1093 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1094 } 1095 1096 /* 1097 * Update the "last cluster of the file" entry in the 1098 * denode's fat cache. 1099 */ 1100 1101 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1102 if ((flags & DE_CLEAR) && 1103 (dep->de_Attributes & ATTR_DIRECTORY)) { 1104 while (got-- > 0) { 1105 bp = getblk(pmp->pm_devvp, cntobn(pmp, cn++), 1106 pmp->pm_bpcluster, 0, 0); 1107 clrbuf(bp); 1108 if (bpp) { 1109 *bpp = bp; 1110 bpp = NULL; 1111 } else { 1112 bdwrite(bp); 1113 } 1114 } 1115 } 1116 } 1117 1118 return (0); 1119 } 1120