Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
FreeBSD/Linux Kernel Cross Reference
sys/fs/msdosfs/msdosfs_fat.c
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
SearchContext: - none - 3 - 10
1 /* $FreeBSD$ */ 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 static int fc_wherefrom, fc_whereto, fc_lastclust; 76 static int pm_fatblocksize; 77 78 static int chainalloc(struct msdosfsmount *pmp, u_long start, 79 u_long count, u_long fillwith, u_long *retcluster, 80 u_long *got); 81 static int chainlength(struct msdosfsmount *pmp, u_long start, 82 u_long count); 83 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 84 u_long *sizep, u_long *bop); 85 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 86 u_long fillwith); 87 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 88 u_long *fsrcnp); 89 static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 90 u_long fatbn); 91 static __inline void 92 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 93 static __inline void 94 usemap_free(struct msdosfsmount *pmp, u_long cn); 95 96 static void 97 fatblock(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 */ 138 int 139 pcbmap(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 } 272 273 hiteof:; 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 */ 287 static void 288 fc_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 */ 315 void 316 fc_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 */ 339 static void 340 updatefats(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 if (bread(pmp->pm_devvp, pmp->pm_fsinfo, pmp->pm_BytesPerSec, 357 NOCRED, &bpn) != 0) { 358 /* 359 * Ignore the error, but turn off FSInfo update for the future. 360 */ 361 pmp->pm_fsinfo = 0; 362 brelse(bpn); 363 } else { 364 struct fsinfo *fp = (struct fsinfo *)bpn->b_data; 365 366 putulong(fp->fsinfree, pmp->pm_freeclustercount); 367 putulong(fp->fsinxtfree, pmp->pm_nxtfree); 368 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 369 bwrite(bpn); 370 else 371 bdwrite(bpn); 372 } 373 } 374 375 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 376 /* 377 * Now copy the block(s) of the modified fat to the other copies of 378 * the fat and write them out. This is faster than reading in the 379 * other fats and then writing them back out. This could tie up 380 * the fat for quite a while. Preventing others from accessing it. 381 * To prevent us from going after the fat quite so much we use 382 * delayed writes, unless they specfied "synchronous" when the 383 * filesystem was mounted. If synch is asked for then use 384 * bwrite()'s and really slow things down. 385 */ 386 for (i = 1; i < pmp->pm_FATs; i++) { 387 fatbn += pmp->pm_FATsecs; 388 /* getblk() never fails */ 389 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 390 0, 0, 0); 391 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 392 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 393 bwrite(bpn); 394 else 395 bdwrite(bpn); 396 } 397 } 398 399 /* 400 * Write out the first (or current) fat last. 401 */ 402 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 403 bwrite(bp); 404 else 405 bdwrite(bp); 406 /* 407 * Maybe update fsinfo sector here? 408 */ 409 } 410 411 /* 412 * Updating entries in 12 bit fats is a pain in the butt. 413 * 414 * The following picture shows where nibbles go when moving from a 12 bit 415 * cluster number into the appropriate bytes in the FAT. 416 * 417 * byte m byte m+1 byte m+2 418 * +----+----+ +----+----+ +----+----+ 419 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 420 * +----+----+ +----+----+ +----+----+ 421 * 422 * +----+----+----+ +----+----+----+ 423 * | 3 0 1 | | 4 5 2 | 424 * +----+----+----+ +----+----+----+ 425 * cluster n cluster n+1 426 * 427 * Where n is even. m = n + (n >> 2) 428 * 429 */ 430 static __inline void 431 usemap_alloc(pmp, cn) 432 struct msdosfsmount *pmp; 433 u_long cn; 434 { 435 436 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 437 pmp->pm_freeclustercount--; 438 } 439 440 static __inline void 441 usemap_free(pmp, cn) 442 struct msdosfsmount *pmp; 443 u_long cn; 444 { 445 446 pmp->pm_freeclustercount++; 447 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 448 } 449 450 int 451 clusterfree(pmp, cluster, oldcnp) 452 struct msdosfsmount *pmp; 453 u_long cluster; 454 u_long *oldcnp; 455 { 456 int error; 457 u_long oldcn; 458 459 usemap_free(pmp, cluster); 460 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 461 if (error) { 462 usemap_alloc(pmp, cluster); 463 return (error); 464 } 465 /* 466 * If the cluster was successfully marked free, then update 467 * the count of free clusters, and turn off the "allocated" 468 * bit in the "in use" cluster bit map. 469 */ 470 if (oldcnp) 471 *oldcnp = oldcn; 472 return (0); 473 } 474 475 /* 476 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 477 * 478 * function - whether to get or set a fat entry 479 * pmp - address of the msdosfsmount structure for the filesystem 480 * whose fat is to be manipulated. 481 * cn - which cluster is of interest 482 * oldcontents - address of a word that is to receive the contents of the 483 * cluster'th entry if this is a get function 484 * newcontents - the new value to be written into the cluster'th element of 485 * the fat if this is a set function. 486 * 487 * This function can also be used to free a cluster by setting the fat entry 488 * for a cluster to 0. 489 * 490 * All copies of the fat are updated if this is a set function. NOTE: If 491 * fatentry() marks a cluster as free it does not update the inusemap in 492 * the msdosfsmount structure. This is left to the caller. 493 */ 494 int 495 fatentry(function, pmp, cn, oldcontents, newcontents) 496 int function; 497 struct msdosfsmount *pmp; 498 u_long cn; 499 u_long *oldcontents; 500 u_long newcontents; 501 { 502 int error; 503 u_long readcn; 504 u_long bn, bo, bsize, byteoffset; 505 struct buf *bp; 506 507 #ifdef MSDOSFS_DEBUG 508 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 509 function, pmp, cn, oldcontents, newcontents); 510 #endif 511 512 #ifdef DIAGNOSTIC 513 /* 514 * Be sure they asked us to do something. 515 */ 516 if ((function & (FAT_SET | FAT_GET)) == 0) { 517 printf("fatentry(): function code doesn't specify get or set\n"); 518 return (EINVAL); 519 } 520 521 /* 522 * If they asked us to return a cluster number but didn't tell us 523 * where to put it, give them an error. 524 */ 525 if ((function & FAT_GET) && oldcontents == NULL) { 526 printf("fatentry(): get function with no place to put result\n"); 527 return (EINVAL); 528 } 529 #endif 530 531 /* 532 * Be sure the requested cluster is in the filesystem. 533 */ 534 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 535 return (EINVAL); 536 537 byteoffset = FATOFS(pmp, cn); 538 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 539 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 540 if (error) { 541 brelse(bp); 542 return (error); 543 } 544 545 if (function & FAT_GET) { 546 if (FAT32(pmp)) 547 readcn = getulong(&bp->b_data[bo]); 548 else 549 readcn = getushort(&bp->b_data[bo]); 550 if (FAT12(pmp) & (cn & 1)) 551 readcn >>= 4; 552 readcn &= pmp->pm_fatmask; 553 /* map reserved fat entries to same values for all fats */ 554 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 555 readcn |= ~pmp->pm_fatmask; 556 *oldcontents = readcn; 557 } 558 if (function & FAT_SET) { 559 switch (pmp->pm_fatmask) { 560 case FAT12_MASK: 561 readcn = getushort(&bp->b_data[bo]); 562 if (cn & 1) { 563 readcn &= 0x000f; 564 readcn |= newcontents << 4; 565 } else { 566 readcn &= 0xf000; 567 readcn |= newcontents & 0xfff; 568 } 569 putushort(&bp->b_data[bo], readcn); 570 break; 571 case FAT16_MASK: 572 putushort(&bp->b_data[bo], newcontents); 573 break; 574 case FAT32_MASK: 575 /* 576 * According to spec we have to retain the 577 * high order bits of the fat entry. 578 */ 579 readcn = getulong(&bp->b_data[bo]); 580 readcn &= ~FAT32_MASK; 581 readcn |= newcontents & FAT32_MASK; 582 putulong(&bp->b_data[bo], readcn); 583 break; 584 } 585 updatefats(pmp, bp, bn); 586 bp = NULL; 587 pmp->pm_fmod = 1; 588 } 589 if (bp) 590 brelse(bp); 591 return (0); 592 } 593 594 /* 595 * Update a contiguous cluster chain 596 * 597 * pmp - mount point 598 * start - first cluster of chain 599 * count - number of clusters in chain 600 * fillwith - what to write into fat entry of last cluster 601 */ 602 static int 603 fatchain(pmp, start, count, fillwith) 604 struct msdosfsmount *pmp; 605 u_long start; 606 u_long count; 607 u_long fillwith; 608 { 609 int error; 610 u_long bn, bo, bsize, byteoffset, readcn, newc; 611 struct buf *bp; 612 613 #ifdef MSDOSFS_DEBUG 614 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 615 pmp, start, count, fillwith); 616 #endif 617 /* 618 * Be sure the clusters are in the filesystem. 619 */ 620 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 621 return (EINVAL); 622 623 while (count > 0) { 624 byteoffset = FATOFS(pmp, start); 625 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 626 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 627 if (error) { 628 brelse(bp); 629 return (error); 630 } 631 while (count > 0) { 632 start++; 633 newc = --count > 0 ? start : fillwith; 634 switch (pmp->pm_fatmask) { 635 case FAT12_MASK: 636 readcn = getushort(&bp->b_data[bo]); 637 if (start & 1) { 638 readcn &= 0xf000; 639 readcn |= newc & 0xfff; 640 } else { 641 readcn &= 0x000f; 642 readcn |= newc << 4; 643 } 644 putushort(&bp->b_data[bo], readcn); 645 bo++; 646 if (!(start & 1)) 647 bo++; 648 break; 649 case FAT16_MASK: 650 putushort(&bp->b_data[bo], newc); 651 bo += 2; 652 break; 653 case FAT32_MASK: 654 readcn = getulong(&bp->b_data[bo]); 655 readcn &= ~pmp->pm_fatmask; 656 readcn |= newc & pmp->pm_fatmask; 657 putulong(&bp->b_data[bo], readcn); 658 bo += 4; 659 break; 660 } 661 if (bo >= bsize) 662 break; 663 } 664 updatefats(pmp, bp, bn); 665 } 666 pmp->pm_fmod = 1; 667 return (0); 668 } 669 670 /* 671 * Check the length of a free cluster chain starting at start. 672 * 673 * pmp - mount point 674 * start - start of chain 675 * count - maximum interesting length 676 */ 677 static int 678 chainlength(pmp, start, count) 679 struct msdosfsmount *pmp; 680 u_long start; 681 u_long count; 682 { 683 u_long idx, max_idx; 684 u_int map; 685 u_long len; 686 687 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 688 idx = start / N_INUSEBITS; 689 start %= N_INUSEBITS; 690 map = pmp->pm_inusemap[idx]; 691 map &= ~((1 << start) - 1); 692 if (map) { 693 len = ffs(map) - 1 - start; 694 return (len > count ? count : len); 695 } 696 len = N_INUSEBITS - start; 697 if (len >= count) 698 return (count); 699 while (++idx <= max_idx) { 700 if (len >= count) 701 break; 702 map = pmp->pm_inusemap[idx]; 703 if (map) { 704 len += ffs(map) - 1; 705 break; 706 } 707 len += N_INUSEBITS; 708 } 709 return (len > count ? count : len); 710 } 711 712 /* 713 * Allocate contigous free clusters. 714 * 715 * pmp - mount point. 716 * start - start of cluster chain. 717 * count - number of clusters to allocate. 718 * fillwith - put this value into the fat entry for the 719 * last allocated cluster. 720 * retcluster - put the first allocated cluster's number here. 721 * got - how many clusters were actually allocated. 722 */ 723 static int 724 chainalloc(pmp, start, count, fillwith, retcluster, got) 725 struct msdosfsmount *pmp; 726 u_long start; 727 u_long count; 728 u_long fillwith; 729 u_long *retcluster; 730 u_long *got; 731 { 732 int error; 733 u_long cl, n; 734 735 for (cl = start, n = count; n-- > 0;) 736 usemap_alloc(pmp, cl++); 737 738 error = fatchain(pmp, start, count, fillwith); 739 if (error != 0) 740 return (error); 741 #ifdef MSDOSFS_DEBUG 742 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 743 start, count); 744 #endif 745 if (retcluster) 746 *retcluster = start; 747 if (got) 748 *got = count; 749 pmp->pm_nxtfree = start + count; 750 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 751 pmp->pm_nxtfree = CLUST_FIRST; 752 return (0); 753 } 754 755 /* 756 * Allocate contiguous free clusters. 757 * 758 * pmp - mount point. 759 * start - preferred start of cluster chain. 760 * count - number of clusters requested. 761 * fillwith - put this value into the fat entry for the 762 * last allocated cluster. 763 * retcluster - put the first allocated cluster's number here. 764 * got - how many clusters were actually allocated. 765 */ 766 int 767 clusteralloc(pmp, start, count, fillwith, retcluster, got) 768 struct msdosfsmount *pmp; 769 u_long start; 770 u_long count; 771 u_long fillwith; 772 u_long *retcluster; 773 u_long *got; 774 { 775 u_long idx; 776 u_long len, newst, foundl, cn, l; 777 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 778 u_int map; 779 780 #ifdef MSDOSFS_DEBUG 781 printf("clusteralloc(): find %lu clusters\n", count); 782 #endif 783 if (start) { 784 if ((len = chainlength(pmp, start, count)) >= count) 785 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 786 } else 787 len = 0; 788 789 newst = pmp->pm_nxtfree; 790 foundl = 0; 791 792 for (cn = newst; cn <= pmp->pm_maxcluster;) { 793 idx = cn / N_INUSEBITS; 794 map = pmp->pm_inusemap[idx]; 795 map |= (1 << (cn % N_INUSEBITS)) - 1; 796 if (map != (u_int)-1) { 797 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 798 if ((l = chainlength(pmp, cn, count)) >= count) 799 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 800 if (l > foundl) { 801 foundcn = cn; 802 foundl = l; 803 } 804 cn += l + 1; 805 continue; 806 } 807 cn += N_INUSEBITS - cn % N_INUSEBITS; 808 } 809 for (cn = 0; cn < newst;) { 810 idx = cn / N_INUSEBITS; 811 map = pmp->pm_inusemap[idx]; 812 map |= (1 << (cn % N_INUSEBITS)) - 1; 813 if (map != (u_int)-1) { 814 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 815 if ((l = chainlength(pmp, cn, count)) >= count) 816 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 817 if (l > foundl) { 818 foundcn = cn; 819 foundl = l; 820 } 821 cn += l + 1; 822 continue; 823 } 824 cn += N_INUSEBITS - cn % N_INUSEBITS; 825 } 826 827 if (!foundl) 828 return (ENOSPC); 829 830 if (len) 831 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 832 else 833 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 834 } 835 836 837 /* 838 * Free a chain of clusters. 839 * 840 * pmp - address of the msdosfs mount structure for the filesystem 841 * containing the cluster chain to be freed. 842 * startcluster - number of the 1st cluster in the chain of clusters to be 843 * freed. 844 */ 845 int 846 freeclusterchain(pmp, cluster) 847 struct msdosfsmount *pmp; 848 u_long cluster; 849 { 850 int error; 851 struct buf *bp = NULL; 852 u_long bn, bo, bsize, byteoffset; 853 u_long readcn, lbn = -1; 854 855 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 856 byteoffset = FATOFS(pmp, cluster); 857 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 858 if (lbn != bn) { 859 if (bp) 860 updatefats(pmp, bp, lbn); 861 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 862 if (error) { 863 brelse(bp); 864 return (error); 865 } 866 lbn = bn; 867 } 868 usemap_free(pmp, cluster); 869 switch (pmp->pm_fatmask) { 870 case FAT12_MASK: 871 readcn = getushort(&bp->b_data[bo]); 872 if (cluster & 1) { 873 cluster = readcn >> 4; 874 readcn &= 0x000f; 875 readcn |= MSDOSFSFREE << 4; 876 } else { 877 cluster = readcn; 878 readcn &= 0xf000; 879 readcn |= MSDOSFSFREE & 0xfff; 880 } 881 putushort(&bp->b_data[bo], readcn); 882 break; 883 case FAT16_MASK: 884 cluster = getushort(&bp->b_data[bo]); 885 putushort(&bp->b_data[bo], MSDOSFSFREE); 886 break; 887 case FAT32_MASK: 888 cluster = getulong(&bp->b_data[bo]); 889 putulong(&bp->b_data[bo], 890 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 891 break; 892 } 893 cluster &= pmp->pm_fatmask; 894 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 895 cluster |= pmp->pm_fatmask; 896 } 897 if (bp) 898 updatefats(pmp, bp, bn); 899 return (0); 900 } 901 902 /* 903 * Read in fat blocks looking for free clusters. For every free cluster 904 * found turn off its corresponding bit in the pm_inusemap. 905 */ 906 int 907 fillinusemap(pmp) 908 struct msdosfsmount *pmp; 909 { 910 struct buf *bp = NULL; 911 u_long cn, readcn; 912 int error; 913 u_long bn, bo, bsize, byteoffset; 914 915 /* 916 * Mark all clusters in use, we mark the free ones in the fat scan 917 * loop further down. 918 */ 919 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 920 pmp->pm_inusemap[cn] = (u_int)-1; 921 922 /* 923 * Figure how many free clusters are in the filesystem by ripping 924 * through the fat counting the number of entries whose content is 925 * zero. These represent free clusters. 926 */ 927 pmp->pm_freeclustercount = 0; 928 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 929 byteoffset = FATOFS(pmp, cn); 930 bo = byteoffset % pmp->pm_fatblocksize; 931 if (!bo || !bp) { 932 /* Read new FAT block */ 933 if (bp) 934 brelse(bp); 935 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 936 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 937 if (error) { 938 brelse(bp); 939 return (error); 940 } 941 } 942 if (FAT32(pmp)) 943 readcn = getulong(&bp->b_data[bo]); 944 else 945 readcn = getushort(&bp->b_data[bo]); 946 if (FAT12(pmp) && (cn & 1)) 947 readcn >>= 4; 948 readcn &= pmp->pm_fatmask; 949 950 if (readcn == 0) 951 usemap_free(pmp, cn); 952 } 953 brelse(bp); 954 return (0); 955 } 956 957 /* 958 * Allocate a new cluster and chain it onto the end of the file. 959 * 960 * dep - the file to extend 961 * count - number of clusters to allocate 962 * bpp - where to return the address of the buf header for the first new 963 * file block 964 * ncp - where to put cluster number of the first newly allocated cluster 965 * If this pointer is 0, do not return the cluster number. 966 * flags - see fat.h 967 * 968 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 969 * the de_flag field of the denode and it does not change the de_FileSize 970 * field. This is left for the caller to do. 971 */ 972 int 973 extendfile(dep, count, bpp, ncp, flags) 974 struct denode *dep; 975 u_long count; 976 struct buf **bpp; 977 u_long *ncp; 978 int flags; 979 { 980 int error; 981 u_long frcn; 982 u_long cn, got; 983 struct msdosfsmount *pmp = dep->de_pmp; 984 struct buf *bp; 985 daddr_t blkno; 986 987 /* 988 * Don't try to extend the root directory 989 */ 990 if (dep->de_StartCluster == MSDOSFSROOT 991 && (dep->de_Attributes & ATTR_DIRECTORY)) { 992 printf("extendfile(): attempt to extend root directory\n"); 993 return (ENOSPC); 994 } 995 996 /* 997 * If the "file's last cluster" cache entry is empty, and the file 998 * is not empty, then fill the cache entry by calling pcbmap(). 999 */ 1000 fc_fileextends++; 1001 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 1002 dep->de_StartCluster != 0) { 1003 fc_lfcempty++; 1004 error = pcbmap(dep, 0xffff, 0, &cn, 0); 1005 /* we expect it to return E2BIG */ 1006 if (error != E2BIG) 1007 return (error); 1008 } 1009 1010 fc_last_to_nexttolast(dep); 1011 while (count > 0) { 1012 /* 1013 * Allocate a new cluster chain and cat onto the end of the 1014 * file. * If the file is empty we make de_StartCluster point 1015 * to the new block. Note that de_StartCluster being 0 is 1016 * sufficient to be sure the file is empty since we exclude 1017 * attempts to extend the root directory above, and the root 1018 * dir is the only file with a startcluster of 0 that has 1019 * blocks allocated (sort of). 1020 */ 1021 if (dep->de_StartCluster == 0) 1022 cn = 0; 1023 else 1024 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1025 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1026 if (error) 1027 return (error); 1028 1029 count -= got; 1030 1031 /* 1032 * Give them the filesystem relative cluster number if they want 1033 * it. 1034 */ 1035 if (ncp) { 1036 *ncp = cn; 1037 ncp = NULL; 1038 } 1039 1040 if (dep->de_StartCluster == 0) { 1041 dep->de_StartCluster = cn; 1042 frcn = 0; 1043 } else { 1044 error = fatentry(FAT_SET, pmp, 1045 dep->de_fc[FC_LASTFC].fc_fsrcn, 1046 0, cn); 1047 if (error) { 1048 clusterfree(pmp, cn, NULL); 1049 return (error); 1050 } 1051 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1052 } 1053 1054 /* 1055 * Update the "last cluster of the file" entry in the denode's fat 1056 * cache. 1057 */ 1058 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1059 1060 if (flags & DE_CLEAR) { 1061 while (got-- > 0) { 1062 /* 1063 * Get the buf header for the new block of the file. 1064 */ 1065 if (dep->de_Attributes & ATTR_DIRECTORY) 1066 bp = getblk(pmp->pm_devvp, 1067 cntobn(pmp, cn++), 1068 pmp->pm_bpcluster, 0, 0, 0); 1069 else { 1070 bp = getblk(DETOV(dep), 1071 frcn++, 1072 pmp->pm_bpcluster, 0, 0, 0); 1073 /* 1074 * Do the bmap now, as in msdosfs_write 1075 */ 1076 if (pcbmap(dep, 1077 bp->b_lblkno, 1078 &blkno, 0, 0)) 1079 bp->b_blkno = -1; 1080 if (bp->b_blkno == -1) 1081 panic("extendfile: pcbmap"); 1082 else 1083 bp->b_blkno = blkno; 1084 } 1085 vfs_bio_clrbuf(bp); 1086 if (bpp) { 1087 *bpp = bp; 1088 bpp = NULL; 1089 } else 1090 bdwrite(bp); 1091 } 1092 } 1093 } 1094 1095 return (0); 1096 } 1097 1098 /*- 1099 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1100 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1101 * this bit is not defined for FAT12 volumes, which are always assumed to 1102 * be dirty. 1103 * 1104 * The fatentry() routine only works on cluster numbers that a file could 1105 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1106 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1107 * 1108 * Inputs: 1109 * pmp The MS-DOS volume to mark 1110 * dirty Non-zero if the volume should be marked dirty; zero if it 1111 * should be marked clean 1112 * 1113 * Result: 1114 * 0 Success 1115 * EROFS Volume is read-only 1116 * ? (other errors from called routines) 1117 */ 1118 int 1119 markvoldirty(struct msdosfsmount *pmp, int dirty) 1120 { 1121 struct buf *bp; 1122 u_long bn, bo, bsize, byteoffset, fatval; 1123 int error; 1124 1125 /* 1126 * FAT12 does not support a "clean" bit, so don't do anything for 1127 * FAT12. 1128 */ 1129 if (FAT12(pmp)) 1130 return (0); 1131 1132 /* Can't change the bit on a read-only filesystem. */ 1133 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1134 return (EROFS); 1135 1136 /* 1137 * Fetch the block containing the FAT entry. It is given by the 1138 * pseudo-cluster 1. 1139 */ 1140 byteoffset = FATOFS(pmp, 1); 1141 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1142 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1143 if (error) { 1144 brelse(bp); 1145 return (error); 1146 } 1147 1148 /* 1149 * Get the current value of the FAT entry and set/clear the relevant 1150 * bit. Dirty means clear the "clean" bit; clean means set the 1151 * "clean" bit. 1152 */ 1153 if (FAT32(pmp)) { 1154 /* FAT32 uses bit 27. */ 1155 fatval = getulong(&bp->b_data[bo]); 1156 if (dirty) 1157 fatval &= 0xF7FFFFFF; 1158 else 1159 fatval |= 0x08000000; 1160 putulong(&bp->b_data[bo], fatval); 1161 } else { 1162 /* Must be FAT16; use bit 15. */ 1163 fatval = getushort(&bp->b_data[bo]); 1164 if (dirty) 1165 fatval &= 0x7FFF; 1166 else 1167 fatval |= 0x8000; 1168 putushort(&bp->b_data[bo], fatval); 1169 } 1170 1171 /* Write out the modified FAT block synchronously. */ 1172 return (bwrite(bp)); 1173 }
Cache object: c96d5e6f2f984a481c7bf09853bf2137
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]