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sys/fs/msdosfs/msdosfs_fat.c
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1 /* $FreeBSD: releng/8.0/sys/fs/msdosfs/msdosfs_fat.c 182600 2008-09-01 13:18:16Z kib $ */ 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 */ 66 static int fc_fileextends; /* # of file extends */ 67 static int fc_lfcempty; /* # of time last file cluster cache entry 68 * was empty */ 69 static int fc_bmapcalls; /* # of times pcbmap was called */ 70 71 #define LMMAX 20 72 static int fc_lmdistance[LMMAX];/* counters for how far off the last 73 * cluster mapped entry was. */ 74 static int fc_largedistance; /* off by more than LMMAX */ 75 76 static int chainalloc(struct msdosfsmount *pmp, u_long start, 77 u_long count, u_long fillwith, u_long *retcluster, 78 u_long *got); 79 static int chainlength(struct msdosfsmount *pmp, u_long start, 80 u_long count); 81 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 82 u_long *sizep, u_long *bop); 83 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 84 u_long fillwith); 85 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 86 u_long *fsrcnp); 87 static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 88 u_long fatbn); 89 static __inline void 90 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 91 static __inline void 92 usemap_free(struct msdosfsmount *pmp, u_long cn); 93 94 static void 95 fatblock(pmp, ofs, bnp, sizep, bop) 96 struct msdosfsmount *pmp; 97 u_long ofs; 98 u_long *bnp; 99 u_long *sizep; 100 u_long *bop; 101 { 102 u_long bn, size; 103 104 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 105 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 106 * DEV_BSIZE; 107 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 108 109 if (bnp) 110 *bnp = bn; 111 if (sizep) 112 *sizep = size; 113 if (bop) 114 *bop = ofs % pmp->pm_fatblocksize; 115 } 116 117 /* 118 * Map the logical cluster number of a file into a physical disk sector 119 * that is filesystem relative. 120 * 121 * dep - address of denode representing the file of interest 122 * findcn - file relative cluster whose filesystem relative cluster number 123 * and/or block number are/is to be found 124 * bnp - address of where to place the filesystem relative block number. 125 * If this pointer is null then don't return this quantity. 126 * cnp - address of where to place the filesystem relative cluster number. 127 * If this pointer is null then don't return this quantity. 128 * 129 * NOTE: Either bnp or cnp must be non-null. 130 * This function has one side effect. If the requested file relative cluster 131 * is beyond the end of file, then the actual number of clusters in the file 132 * is returned in *cnp. This is useful for determining how long a directory is. 133 * If cnp is null, nothing is returned. 134 */ 135 int 136 pcbmap(dep, findcn, bnp, cnp, sp) 137 struct denode *dep; 138 u_long findcn; /* file relative cluster to get */ 139 daddr_t *bnp; /* returned filesys relative blk number */ 140 u_long *cnp; /* returned cluster number */ 141 int *sp; /* returned block size */ 142 { 143 int error; 144 u_long i; 145 u_long cn; 146 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 147 u_long byteoffset; 148 u_long bn; 149 u_long bo; 150 struct buf *bp = NULL; 151 u_long bp_bn = -1; 152 struct msdosfsmount *pmp = dep->de_pmp; 153 u_long bsize; 154 155 fc_bmapcalls++; 156 157 /* 158 * If they don't give us someplace to return a value then don't 159 * bother doing anything. 160 */ 161 if (bnp == NULL && cnp == NULL && sp == NULL) 162 return (0); 163 164 cn = dep->de_StartCluster; 165 /* 166 * The "file" that makes up the root directory is contiguous, 167 * permanently allocated, of fixed size, and is not made up of 168 * clusters. If the cluster number is beyond the end of the root 169 * directory, then return the number of clusters in the file. 170 */ 171 if (cn == MSDOSFSROOT) { 172 if (dep->de_Attributes & ATTR_DIRECTORY) { 173 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 174 if (cnp) 175 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 176 return (E2BIG); 177 } 178 if (bnp) 179 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 180 if (cnp) 181 *cnp = MSDOSFSROOT; 182 if (sp) 183 *sp = min(pmp->pm_bpcluster, 184 dep->de_FileSize - de_cn2off(pmp, findcn)); 185 return (0); 186 } else { /* just an empty file */ 187 if (cnp) 188 *cnp = 0; 189 return (E2BIG); 190 } 191 } 192 193 /* 194 * All other files do I/O in cluster sized blocks 195 */ 196 if (sp) 197 *sp = pmp->pm_bpcluster; 198 199 /* 200 * Rummage around in the fat cache, maybe we can avoid tromping 201 * thru every fat entry for the file. And, keep track of how far 202 * off the cache was from where we wanted to be. 203 */ 204 i = 0; 205 fc_lookup(dep, findcn, &i, &cn); 206 if ((bn = findcn - i) >= LMMAX) 207 fc_largedistance++; 208 else 209 fc_lmdistance[bn]++; 210 211 /* 212 * Handle all other files or directories the normal way. 213 */ 214 for (; i < findcn; i++) { 215 /* 216 * Stop with all reserved clusters, not just with EOF. 217 */ 218 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 219 goto hiteof; 220 byteoffset = FATOFS(pmp, cn); 221 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 222 if (bn != bp_bn) { 223 if (bp) 224 brelse(bp); 225 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 226 if (error) { 227 brelse(bp); 228 return (error); 229 } 230 bp_bn = bn; 231 } 232 prevcn = cn; 233 if (bo >= bsize) { 234 if (bp) 235 brelse(bp); 236 return (EIO); 237 } 238 if (FAT32(pmp)) 239 cn = getulong(&bp->b_data[bo]); 240 else 241 cn = getushort(&bp->b_data[bo]); 242 if (FAT12(pmp) && (prevcn & 1)) 243 cn >>= 4; 244 cn &= pmp->pm_fatmask; 245 246 /* 247 * Force the special cluster numbers 248 * to be the same for all cluster sizes 249 * to let the rest of msdosfs handle 250 * all cases the same. 251 */ 252 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 253 cn |= ~pmp->pm_fatmask; 254 } 255 256 if (!MSDOSFSEOF(pmp, cn)) { 257 if (bp) 258 brelse(bp); 259 if (bnp) 260 *bnp = cntobn(pmp, cn); 261 if (cnp) 262 *cnp = cn; 263 fc_setcache(dep, FC_LASTMAP, i, cn); 264 return (0); 265 } 266 267 hiteof:; 268 if (cnp) 269 *cnp = i; 270 if (bp) 271 brelse(bp); 272 /* update last file cluster entry in the fat cache */ 273 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 274 return (E2BIG); 275 } 276 277 /* 278 * Find the closest entry in the fat cache to the cluster we are looking 279 * for. 280 */ 281 static void 282 fc_lookup(dep, findcn, frcnp, fsrcnp) 283 struct denode *dep; 284 u_long findcn; 285 u_long *frcnp; 286 u_long *fsrcnp; 287 { 288 int i; 289 u_long cn; 290 struct fatcache *closest = 0; 291 292 for (i = 0; i < FC_SIZE; i++) { 293 cn = dep->de_fc[i].fc_frcn; 294 if (cn != FCE_EMPTY && cn <= findcn) { 295 if (closest == 0 || cn > closest->fc_frcn) 296 closest = &dep->de_fc[i]; 297 } 298 } 299 if (closest) { 300 *frcnp = closest->fc_frcn; 301 *fsrcnp = closest->fc_fsrcn; 302 } 303 } 304 305 /* 306 * Purge the fat cache in denode dep of all entries relating to file 307 * relative cluster frcn and beyond. 308 */ 309 void 310 fc_purge(dep, frcn) 311 struct denode *dep; 312 u_int frcn; 313 { 314 int i; 315 struct fatcache *fcp; 316 317 fcp = dep->de_fc; 318 for (i = 0; i < FC_SIZE; i++, fcp++) { 319 if (fcp->fc_frcn >= frcn) 320 fcp->fc_frcn = FCE_EMPTY; 321 } 322 } 323 324 /* 325 * Update the fat. 326 * If mirroring the fat, update all copies, with the first copy as last. 327 * Else update only the current fat (ignoring the others). 328 * 329 * pmp - msdosfsmount structure for filesystem to update 330 * bp - addr of modified fat block 331 * fatbn - block number relative to begin of filesystem of the modified fat block. 332 */ 333 static void 334 updatefats(pmp, bp, fatbn) 335 struct msdosfsmount *pmp; 336 struct buf *bp; 337 u_long fatbn; 338 { 339 int i; 340 struct buf *bpn; 341 342 #ifdef MSDOSFS_DEBUG 343 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 344 #endif 345 346 /* 347 * If we have an FSInfo block, update it. 348 */ 349 if (pmp->pm_fsinfo) { 350 if (bread(pmp->pm_devvp, pmp->pm_fsinfo, pmp->pm_BytesPerSec, 351 NOCRED, &bpn) != 0) { 352 /* 353 * Ignore the error, but turn off FSInfo update for the future. 354 */ 355 pmp->pm_fsinfo = 0; 356 brelse(bpn); 357 } else { 358 struct fsinfo *fp = (struct fsinfo *)bpn->b_data; 359 360 putulong(fp->fsinfree, pmp->pm_freeclustercount); 361 putulong(fp->fsinxtfree, pmp->pm_nxtfree); 362 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 363 bwrite(bpn); 364 else 365 bdwrite(bpn); 366 } 367 } 368 369 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 370 /* 371 * Now copy the block(s) of the modified fat to the other copies of 372 * the fat and write them out. This is faster than reading in the 373 * other fats and then writing them back out. This could tie up 374 * the fat for quite a while. Preventing others from accessing it. 375 * To prevent us from going after the fat quite so much we use 376 * delayed writes, unless they specfied "synchronous" when the 377 * filesystem was mounted. If synch is asked for then use 378 * bwrite()'s and really slow things down. 379 */ 380 for (i = 1; i < pmp->pm_FATs; i++) { 381 fatbn += pmp->pm_FATsecs; 382 /* getblk() never fails */ 383 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 384 0, 0, 0); 385 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 386 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 387 bwrite(bpn); 388 else 389 bdwrite(bpn); 390 } 391 } 392 393 /* 394 * Write out the first (or current) fat last. 395 */ 396 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 397 bwrite(bp); 398 else 399 bdwrite(bp); 400 /* 401 * Maybe update fsinfo sector here? 402 */ 403 } 404 405 /* 406 * Updating entries in 12 bit fats is a pain in the butt. 407 * 408 * The following picture shows where nibbles go when moving from a 12 bit 409 * cluster number into the appropriate bytes in the FAT. 410 * 411 * byte m byte m+1 byte m+2 412 * +----+----+ +----+----+ +----+----+ 413 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 414 * +----+----+ +----+----+ +----+----+ 415 * 416 * +----+----+----+ +----+----+----+ 417 * | 3 0 1 | | 4 5 2 | 418 * +----+----+----+ +----+----+----+ 419 * cluster n cluster n+1 420 * 421 * Where n is even. m = n + (n >> 2) 422 * 423 */ 424 static __inline void 425 usemap_alloc(pmp, cn) 426 struct msdosfsmount *pmp; 427 u_long cn; 428 { 429 430 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 431 pmp->pm_freeclustercount--; 432 } 433 434 static __inline void 435 usemap_free(pmp, cn) 436 struct msdosfsmount *pmp; 437 u_long cn; 438 { 439 440 pmp->pm_freeclustercount++; 441 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 442 } 443 444 int 445 clusterfree(pmp, cluster, oldcnp) 446 struct msdosfsmount *pmp; 447 u_long cluster; 448 u_long *oldcnp; 449 { 450 int error; 451 u_long oldcn; 452 453 usemap_free(pmp, cluster); 454 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 455 if (error) { 456 usemap_alloc(pmp, cluster); 457 return (error); 458 } 459 /* 460 * If the cluster was successfully marked free, then update 461 * the count of free clusters, and turn off the "allocated" 462 * bit in the "in use" cluster bit map. 463 */ 464 if (oldcnp) 465 *oldcnp = oldcn; 466 return (0); 467 } 468 469 /* 470 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 471 * 472 * function - whether to get or set a fat entry 473 * pmp - address of the msdosfsmount structure for the filesystem 474 * whose fat is to be manipulated. 475 * cn - which cluster is of interest 476 * oldcontents - address of a word that is to receive the contents of the 477 * cluster'th entry if this is a get function 478 * newcontents - the new value to be written into the cluster'th element of 479 * the fat if this is a set function. 480 * 481 * This function can also be used to free a cluster by setting the fat entry 482 * for a cluster to 0. 483 * 484 * All copies of the fat are updated if this is a set function. NOTE: If 485 * fatentry() marks a cluster as free it does not update the inusemap in 486 * the msdosfsmount structure. This is left to the caller. 487 */ 488 int 489 fatentry(function, pmp, cn, oldcontents, newcontents) 490 int function; 491 struct msdosfsmount *pmp; 492 u_long cn; 493 u_long *oldcontents; 494 u_long newcontents; 495 { 496 int error; 497 u_long readcn; 498 u_long bn, bo, bsize, byteoffset; 499 struct buf *bp; 500 501 #ifdef MSDOSFS_DEBUG 502 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 503 function, pmp, cn, oldcontents, newcontents); 504 #endif 505 506 #ifdef DIAGNOSTIC 507 /* 508 * Be sure they asked us to do something. 509 */ 510 if ((function & (FAT_SET | FAT_GET)) == 0) { 511 printf("fatentry(): function code doesn't specify get or set\n"); 512 return (EINVAL); 513 } 514 515 /* 516 * If they asked us to return a cluster number but didn't tell us 517 * where to put it, give them an error. 518 */ 519 if ((function & FAT_GET) && oldcontents == NULL) { 520 printf("fatentry(): get function with no place to put result\n"); 521 return (EINVAL); 522 } 523 #endif 524 525 /* 526 * Be sure the requested cluster is in the filesystem. 527 */ 528 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 529 return (EINVAL); 530 531 byteoffset = FATOFS(pmp, cn); 532 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 533 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 534 if (error) { 535 brelse(bp); 536 return (error); 537 } 538 539 if (function & FAT_GET) { 540 if (FAT32(pmp)) 541 readcn = getulong(&bp->b_data[bo]); 542 else 543 readcn = getushort(&bp->b_data[bo]); 544 if (FAT12(pmp) & (cn & 1)) 545 readcn >>= 4; 546 readcn &= pmp->pm_fatmask; 547 /* map reserved fat entries to same values for all fats */ 548 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 549 readcn |= ~pmp->pm_fatmask; 550 *oldcontents = readcn; 551 } 552 if (function & FAT_SET) { 553 switch (pmp->pm_fatmask) { 554 case FAT12_MASK: 555 readcn = getushort(&bp->b_data[bo]); 556 if (cn & 1) { 557 readcn &= 0x000f; 558 readcn |= newcontents << 4; 559 } else { 560 readcn &= 0xf000; 561 readcn |= newcontents & 0xfff; 562 } 563 putushort(&bp->b_data[bo], readcn); 564 break; 565 case FAT16_MASK: 566 putushort(&bp->b_data[bo], newcontents); 567 break; 568 case FAT32_MASK: 569 /* 570 * According to spec we have to retain the 571 * high order bits of the fat entry. 572 */ 573 readcn = getulong(&bp->b_data[bo]); 574 readcn &= ~FAT32_MASK; 575 readcn |= newcontents & FAT32_MASK; 576 putulong(&bp->b_data[bo], readcn); 577 break; 578 } 579 updatefats(pmp, bp, bn); 580 bp = NULL; 581 pmp->pm_fmod = 1; 582 } 583 if (bp) 584 brelse(bp); 585 return (0); 586 } 587 588 /* 589 * Update a contiguous cluster chain 590 * 591 * pmp - mount point 592 * start - first cluster of chain 593 * count - number of clusters in chain 594 * fillwith - what to write into fat entry of last cluster 595 */ 596 static int 597 fatchain(pmp, start, count, fillwith) 598 struct msdosfsmount *pmp; 599 u_long start; 600 u_long count; 601 u_long fillwith; 602 { 603 int error; 604 u_long bn, bo, bsize, byteoffset, readcn, newc; 605 struct buf *bp; 606 607 #ifdef MSDOSFS_DEBUG 608 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 609 pmp, start, count, fillwith); 610 #endif 611 /* 612 * Be sure the clusters are in the filesystem. 613 */ 614 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 615 return (EINVAL); 616 617 while (count > 0) { 618 byteoffset = FATOFS(pmp, start); 619 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 620 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 621 if (error) { 622 brelse(bp); 623 return (error); 624 } 625 while (count > 0) { 626 start++; 627 newc = --count > 0 ? start : fillwith; 628 switch (pmp->pm_fatmask) { 629 case FAT12_MASK: 630 readcn = getushort(&bp->b_data[bo]); 631 if (start & 1) { 632 readcn &= 0xf000; 633 readcn |= newc & 0xfff; 634 } else { 635 readcn &= 0x000f; 636 readcn |= newc << 4; 637 } 638 putushort(&bp->b_data[bo], readcn); 639 bo++; 640 if (!(start & 1)) 641 bo++; 642 break; 643 case FAT16_MASK: 644 putushort(&bp->b_data[bo], newc); 645 bo += 2; 646 break; 647 case FAT32_MASK: 648 readcn = getulong(&bp->b_data[bo]); 649 readcn &= ~pmp->pm_fatmask; 650 readcn |= newc & pmp->pm_fatmask; 651 putulong(&bp->b_data[bo], readcn); 652 bo += 4; 653 break; 654 } 655 if (bo >= bsize) 656 break; 657 } 658 updatefats(pmp, bp, bn); 659 } 660 pmp->pm_fmod = 1; 661 return (0); 662 } 663 664 /* 665 * Check the length of a free cluster chain starting at start. 666 * 667 * pmp - mount point 668 * start - start of chain 669 * count - maximum interesting length 670 */ 671 static int 672 chainlength(pmp, start, count) 673 struct msdosfsmount *pmp; 674 u_long start; 675 u_long count; 676 { 677 u_long idx, max_idx; 678 u_int map; 679 u_long len; 680 681 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 682 idx = start / N_INUSEBITS; 683 start %= N_INUSEBITS; 684 map = pmp->pm_inusemap[idx]; 685 map &= ~((1 << start) - 1); 686 if (map) { 687 len = ffs(map) - 1 - start; 688 return (len > count ? count : len); 689 } 690 len = N_INUSEBITS - start; 691 if (len >= count) 692 return (count); 693 while (++idx <= max_idx) { 694 if (len >= count) 695 break; 696 map = pmp->pm_inusemap[idx]; 697 if (map) { 698 len += ffs(map) - 1; 699 break; 700 } 701 len += N_INUSEBITS; 702 } 703 return (len > count ? count : len); 704 } 705 706 /* 707 * Allocate contigous free clusters. 708 * 709 * pmp - mount point. 710 * start - start of cluster chain. 711 * count - number of clusters to allocate. 712 * fillwith - put this value into the fat entry for the 713 * last allocated cluster. 714 * retcluster - put the first allocated cluster's number here. 715 * got - how many clusters were actually allocated. 716 */ 717 static int 718 chainalloc(pmp, start, count, fillwith, retcluster, got) 719 struct msdosfsmount *pmp; 720 u_long start; 721 u_long count; 722 u_long fillwith; 723 u_long *retcluster; 724 u_long *got; 725 { 726 int error; 727 u_long cl, n; 728 729 for (cl = start, n = count; n-- > 0;) 730 usemap_alloc(pmp, cl++); 731 732 error = fatchain(pmp, start, count, fillwith); 733 if (error != 0) 734 return (error); 735 #ifdef MSDOSFS_DEBUG 736 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 737 start, count); 738 #endif 739 if (retcluster) 740 *retcluster = start; 741 if (got) 742 *got = count; 743 pmp->pm_nxtfree = start + count; 744 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 745 pmp->pm_nxtfree = CLUST_FIRST; 746 return (0); 747 } 748 749 /* 750 * Allocate contiguous free clusters. 751 * 752 * pmp - mount point. 753 * start - preferred start of cluster chain. 754 * count - number of clusters requested. 755 * fillwith - put this value into the fat entry for the 756 * last allocated cluster. 757 * retcluster - put the first allocated cluster's number here. 758 * got - how many clusters were actually allocated. 759 */ 760 int 761 clusteralloc(pmp, start, count, fillwith, retcluster, got) 762 struct msdosfsmount *pmp; 763 u_long start; 764 u_long count; 765 u_long fillwith; 766 u_long *retcluster; 767 u_long *got; 768 { 769 u_long idx; 770 u_long len, newst, foundl, cn, l; 771 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 772 u_int map; 773 774 #ifdef MSDOSFS_DEBUG 775 printf("clusteralloc(): find %lu clusters\n", count); 776 #endif 777 if (start) { 778 if ((len = chainlength(pmp, start, count)) >= count) 779 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 780 } else 781 len = 0; 782 783 newst = pmp->pm_nxtfree; 784 foundl = 0; 785 786 for (cn = newst; cn <= pmp->pm_maxcluster;) { 787 idx = cn / N_INUSEBITS; 788 map = pmp->pm_inusemap[idx]; 789 map |= (1 << (cn % N_INUSEBITS)) - 1; 790 if (map != (u_int)-1) { 791 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 792 if ((l = chainlength(pmp, cn, count)) >= count) 793 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 794 if (l > foundl) { 795 foundcn = cn; 796 foundl = l; 797 } 798 cn += l + 1; 799 continue; 800 } 801 cn += N_INUSEBITS - cn % N_INUSEBITS; 802 } 803 for (cn = 0; cn < newst;) { 804 idx = cn / N_INUSEBITS; 805 map = pmp->pm_inusemap[idx]; 806 map |= (1 << (cn % N_INUSEBITS)) - 1; 807 if (map != (u_int)-1) { 808 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 809 if ((l = chainlength(pmp, cn, count)) >= count) 810 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 811 if (l > foundl) { 812 foundcn = cn; 813 foundl = l; 814 } 815 cn += l + 1; 816 continue; 817 } 818 cn += N_INUSEBITS - cn % N_INUSEBITS; 819 } 820 821 if (!foundl) 822 return (ENOSPC); 823 824 if (len) 825 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 826 else 827 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 828 } 829 830 831 /* 832 * Free a chain of clusters. 833 * 834 * pmp - address of the msdosfs mount structure for the filesystem 835 * containing the cluster chain to be freed. 836 * startcluster - number of the 1st cluster in the chain of clusters to be 837 * freed. 838 */ 839 int 840 freeclusterchain(pmp, cluster) 841 struct msdosfsmount *pmp; 842 u_long cluster; 843 { 844 int error; 845 struct buf *bp = NULL; 846 u_long bn, bo, bsize, byteoffset; 847 u_long readcn, lbn = -1; 848 849 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 850 byteoffset = FATOFS(pmp, cluster); 851 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 852 if (lbn != bn) { 853 if (bp) 854 updatefats(pmp, bp, lbn); 855 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 856 if (error) { 857 brelse(bp); 858 return (error); 859 } 860 lbn = bn; 861 } 862 usemap_free(pmp, cluster); 863 switch (pmp->pm_fatmask) { 864 case FAT12_MASK: 865 readcn = getushort(&bp->b_data[bo]); 866 if (cluster & 1) { 867 cluster = readcn >> 4; 868 readcn &= 0x000f; 869 readcn |= MSDOSFSFREE << 4; 870 } else { 871 cluster = readcn; 872 readcn &= 0xf000; 873 readcn |= MSDOSFSFREE & 0xfff; 874 } 875 putushort(&bp->b_data[bo], readcn); 876 break; 877 case FAT16_MASK: 878 cluster = getushort(&bp->b_data[bo]); 879 putushort(&bp->b_data[bo], MSDOSFSFREE); 880 break; 881 case FAT32_MASK: 882 cluster = getulong(&bp->b_data[bo]); 883 putulong(&bp->b_data[bo], 884 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 885 break; 886 } 887 cluster &= pmp->pm_fatmask; 888 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 889 cluster |= pmp->pm_fatmask; 890 } 891 if (bp) 892 updatefats(pmp, bp, bn); 893 return (0); 894 } 895 896 /* 897 * Read in fat blocks looking for free clusters. For every free cluster 898 * found turn off its corresponding bit in the pm_inusemap. 899 */ 900 int 901 fillinusemap(pmp) 902 struct msdosfsmount *pmp; 903 { 904 struct buf *bp = NULL; 905 u_long cn, readcn; 906 int error; 907 u_long bn, bo, bsize, byteoffset; 908 909 /* 910 * Mark all clusters in use, we mark the free ones in the fat scan 911 * loop further down. 912 */ 913 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 914 pmp->pm_inusemap[cn] = (u_int)-1; 915 916 /* 917 * Figure how many free clusters are in the filesystem by ripping 918 * through the fat counting the number of entries whose content is 919 * zero. These represent free clusters. 920 */ 921 pmp->pm_freeclustercount = 0; 922 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 923 byteoffset = FATOFS(pmp, cn); 924 bo = byteoffset % pmp->pm_fatblocksize; 925 if (!bo || !bp) { 926 /* Read new FAT block */ 927 if (bp) 928 brelse(bp); 929 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 930 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 931 if (error) { 932 brelse(bp); 933 return (error); 934 } 935 } 936 if (FAT32(pmp)) 937 readcn = getulong(&bp->b_data[bo]); 938 else 939 readcn = getushort(&bp->b_data[bo]); 940 if (FAT12(pmp) && (cn & 1)) 941 readcn >>= 4; 942 readcn &= pmp->pm_fatmask; 943 944 if (readcn == 0) 945 usemap_free(pmp, cn); 946 } 947 brelse(bp); 948 return (0); 949 } 950 951 /* 952 * Allocate a new cluster and chain it onto the end of the file. 953 * 954 * dep - the file to extend 955 * count - number of clusters to allocate 956 * bpp - where to return the address of the buf header for the first new 957 * file block 958 * ncp - where to put cluster number of the first newly allocated cluster 959 * If this pointer is 0, do not return the cluster number. 960 * flags - see fat.h 961 * 962 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 963 * the de_flag field of the denode and it does not change the de_FileSize 964 * field. This is left for the caller to do. 965 */ 966 int 967 extendfile(dep, count, bpp, ncp, flags) 968 struct denode *dep; 969 u_long count; 970 struct buf **bpp; 971 u_long *ncp; 972 int flags; 973 { 974 int error; 975 u_long frcn; 976 u_long cn, got; 977 struct msdosfsmount *pmp = dep->de_pmp; 978 struct buf *bp; 979 daddr_t blkno; 980 981 /* 982 * Don't try to extend the root directory 983 */ 984 if (dep->de_StartCluster == MSDOSFSROOT 985 && (dep->de_Attributes & ATTR_DIRECTORY)) { 986 printf("extendfile(): attempt to extend root directory\n"); 987 return (ENOSPC); 988 } 989 990 /* 991 * If the "file's last cluster" cache entry is empty, and the file 992 * is not empty, then fill the cache entry by calling pcbmap(). 993 */ 994 fc_fileextends++; 995 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 996 dep->de_StartCluster != 0) { 997 fc_lfcempty++; 998 error = pcbmap(dep, 0xffff, 0, &cn, 0); 999 /* we expect it to return E2BIG */ 1000 if (error != E2BIG) 1001 return (error); 1002 } 1003 1004 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 1005 dep->de_fc[FC_LASTFC].fc_frcn; 1006 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 1007 dep->de_fc[FC_LASTFC].fc_fsrcn; 1008 while (count > 0) { 1009 /* 1010 * Allocate a new cluster chain and cat onto the end of the 1011 * file. * If the file is empty we make de_StartCluster point 1012 * to the new block. Note that de_StartCluster being 0 is 1013 * sufficient to be sure the file is empty since we exclude 1014 * attempts to extend the root directory above, and the root 1015 * dir is the only file with a startcluster of 0 that has 1016 * blocks allocated (sort of). 1017 */ 1018 if (dep->de_StartCluster == 0) 1019 cn = 0; 1020 else 1021 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1022 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1023 if (error) 1024 return (error); 1025 1026 count -= got; 1027 1028 /* 1029 * Give them the filesystem relative cluster number if they want 1030 * it. 1031 */ 1032 if (ncp) { 1033 *ncp = cn; 1034 ncp = NULL; 1035 } 1036 1037 if (dep->de_StartCluster == 0) { 1038 dep->de_StartCluster = cn; 1039 frcn = 0; 1040 } else { 1041 error = fatentry(FAT_SET, pmp, 1042 dep->de_fc[FC_LASTFC].fc_fsrcn, 1043 0, cn); 1044 if (error) { 1045 clusterfree(pmp, cn, NULL); 1046 return (error); 1047 } 1048 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1049 } 1050 1051 /* 1052 * Update the "last cluster of the file" entry in the denode's fat 1053 * cache. 1054 */ 1055 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1056 1057 if (flags & DE_CLEAR) { 1058 while (got-- > 0) { 1059 /* 1060 * Get the buf header for the new block of the file. 1061 */ 1062 if (dep->de_Attributes & ATTR_DIRECTORY) 1063 bp = getblk(pmp->pm_devvp, 1064 cntobn(pmp, cn++), 1065 pmp->pm_bpcluster, 0, 0, 0); 1066 else { 1067 bp = getblk(DETOV(dep), 1068 frcn++, 1069 pmp->pm_bpcluster, 0, 0, 0); 1070 /* 1071 * Do the bmap now, as in msdosfs_write 1072 */ 1073 if (pcbmap(dep, 1074 bp->b_lblkno, 1075 &blkno, 0, 0)) 1076 bp->b_blkno = -1; 1077 if (bp->b_blkno == -1) 1078 panic("extendfile: pcbmap"); 1079 else 1080 bp->b_blkno = blkno; 1081 } 1082 vfs_bio_clrbuf(bp); 1083 if (bpp) { 1084 *bpp = bp; 1085 bpp = NULL; 1086 } else 1087 bdwrite(bp); 1088 } 1089 } 1090 } 1091 1092 return (0); 1093 } 1094 1095 /*- 1096 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1097 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1098 * this bit is not defined for FAT12 volumes, which are always assumed to 1099 * be dirty. 1100 * 1101 * The fatentry() routine only works on cluster numbers that a file could 1102 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1103 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1104 * 1105 * Inputs: 1106 * pmp The MS-DOS volume to mark 1107 * dirty Non-zero if the volume should be marked dirty; zero if it 1108 * should be marked clean 1109 * 1110 * Result: 1111 * 0 Success 1112 * EROFS Volume is read-only 1113 * ? (other errors from called routines) 1114 */ 1115 int 1116 markvoldirty(struct msdosfsmount *pmp, int dirty) 1117 { 1118 struct buf *bp; 1119 u_long bn, bo, bsize, byteoffset, fatval; 1120 int error; 1121 1122 /* 1123 * FAT12 does not support a "clean" bit, so don't do anything for 1124 * FAT12. 1125 */ 1126 if (FAT12(pmp)) 1127 return (0); 1128 1129 /* Can't change the bit on a read-only filesystem. */ 1130 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1131 return (EROFS); 1132 1133 /* 1134 * Fetch the block containing the FAT entry. It is given by the 1135 * pseudo-cluster 1. 1136 */ 1137 byteoffset = FATOFS(pmp, 1); 1138 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1139 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1140 if (error) { 1141 brelse(bp); 1142 return (error); 1143 } 1144 1145 /* 1146 * Get the current value of the FAT entry and set/clear the relevant 1147 * bit. Dirty means clear the "clean" bit; clean means set the 1148 * "clean" bit. 1149 */ 1150 if (FAT32(pmp)) { 1151 /* FAT32 uses bit 27. */ 1152 fatval = getulong(&bp->b_data[bo]); 1153 if (dirty) 1154 fatval &= 0xF7FFFFFF; 1155 else 1156 fatval |= 0x08000000; 1157 putulong(&bp->b_data[bo], fatval); 1158 } else { 1159 /* Must be FAT16; use bit 15. */ 1160 fatval = getushort(&bp->b_data[bo]); 1161 if (dirty) 1162 fatval &= 0x7FFF; 1163 else 1164 fatval |= 0x8000; 1165 putushort(&bp->b_data[bo], fatval); 1166 } 1167 1168 /* Write out the modified FAT block synchronously. */ 1169 return (bwrite(bp)); 1170 }
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