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sys/fs/msdosfs/msdosfs_fat.c
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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 /* 52 * kernel include files. 53 */ 54 #include <sys/param.h> 55 #include <sys/systm.h> 56 #include <sys/bio.h> 57 #include <sys/buf.h> 58 #include <sys/mount.h> /* to define statfs structure */ 59 #include <sys/vnode.h> /* to define vattr structure */ 60 61 /* 62 * msdosfs include files. 63 */ 64 #include <fs/msdosfs/bpb.h> 65 #include <fs/msdosfs/msdosfsmount.h> 66 #include <fs/msdosfs/direntry.h> 67 #include <fs/msdosfs/denode.h> 68 #include <fs/msdosfs/fat.h> 69 70 /* 71 * Fat cache stats. 72 */ 73 static int fc_fileextends; /* # of file extends */ 74 static int fc_lfcempty; /* # of time last file cluster cache entry 75 * was empty */ 76 static int fc_bmapcalls; /* # of times pcbmap was called */ 77 78 #define LMMAX 20 79 static int fc_lmdistance[LMMAX];/* counters for how far off the last 80 * cluster mapped entry was. */ 81 static int fc_largedistance; /* off by more than LMMAX */ 82 83 static int chainalloc(struct msdosfsmount *pmp, u_long start, 84 u_long count, u_long fillwith, u_long *retcluster, 85 u_long *got); 86 static int chainlength(struct msdosfsmount *pmp, u_long start, 87 u_long count); 88 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 89 u_long *sizep, u_long *bop); 90 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 91 u_long fillwith); 92 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 93 u_long *fsrcnp); 94 static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 95 u_long fatbn); 96 static __inline void 97 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 98 static __inline void 99 usemap_free(struct msdosfsmount *pmp, u_long cn); 100 101 static void 102 fatblock(pmp, ofs, bnp, sizep, bop) 103 struct msdosfsmount *pmp; 104 u_long ofs; 105 u_long *bnp; 106 u_long *sizep; 107 u_long *bop; 108 { 109 u_long bn, size; 110 111 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 112 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 113 * DEV_BSIZE; 114 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 115 116 if (bnp) 117 *bnp = bn; 118 if (sizep) 119 *sizep = size; 120 if (bop) 121 *bop = ofs % pmp->pm_fatblocksize; 122 } 123 124 /* 125 * Map the logical cluster number of a file into a physical disk sector 126 * that is filesystem relative. 127 * 128 * dep - address of denode representing the file of interest 129 * findcn - file relative cluster whose filesystem relative cluster number 130 * and/or block number are/is to be found 131 * bnp - address of where to place the filesystem relative block number. 132 * If this pointer is null then don't return this quantity. 133 * cnp - address of where to place the filesystem relative cluster number. 134 * If this pointer is null then don't return this quantity. 135 * 136 * NOTE: Either bnp or cnp must be non-null. 137 * This function has one side effect. If the requested file relative cluster 138 * is beyond the end of file, then the actual number of clusters in the file 139 * is returned in *cnp. This is useful for determining how long a directory is. 140 * If cnp is null, nothing is returned. 141 */ 142 int 143 pcbmap(dep, findcn, bnp, cnp, sp) 144 struct denode *dep; 145 u_long findcn; /* file relative cluster to get */ 146 daddr_t *bnp; /* returned filesys relative blk number */ 147 u_long *cnp; /* returned cluster number */ 148 int *sp; /* returned block size */ 149 { 150 int error; 151 u_long i; 152 u_long cn; 153 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 154 u_long byteoffset; 155 u_long bn; 156 u_long bo; 157 struct buf *bp = NULL; 158 u_long bp_bn = -1; 159 struct msdosfsmount *pmp = dep->de_pmp; 160 u_long bsize; 161 162 fc_bmapcalls++; 163 164 /* 165 * If they don't give us someplace to return a value then don't 166 * bother doing anything. 167 */ 168 if (bnp == NULL && cnp == NULL && sp == NULL) 169 return (0); 170 171 cn = dep->de_StartCluster; 172 /* 173 * The "file" that makes up the root directory is contiguous, 174 * permanently allocated, of fixed size, and is not made up of 175 * clusters. If the cluster number is beyond the end of the root 176 * directory, then return the number of clusters in the file. 177 */ 178 if (cn == MSDOSFSROOT) { 179 if (dep->de_Attributes & ATTR_DIRECTORY) { 180 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 181 if (cnp) 182 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 183 return (E2BIG); 184 } 185 if (bnp) 186 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 187 if (cnp) 188 *cnp = MSDOSFSROOT; 189 if (sp) 190 *sp = min(pmp->pm_bpcluster, 191 dep->de_FileSize - de_cn2off(pmp, findcn)); 192 return (0); 193 } else { /* just an empty file */ 194 if (cnp) 195 *cnp = 0; 196 return (E2BIG); 197 } 198 } 199 200 /* 201 * All other files do I/O in cluster sized blocks 202 */ 203 if (sp) 204 *sp = pmp->pm_bpcluster; 205 206 /* 207 * Rummage around in the fat cache, maybe we can avoid tromping 208 * thru every fat entry for the file. And, keep track of how far 209 * off the cache was from where we wanted to be. 210 */ 211 i = 0; 212 fc_lookup(dep, findcn, &i, &cn); 213 if ((bn = findcn - i) >= LMMAX) 214 fc_largedistance++; 215 else 216 fc_lmdistance[bn]++; 217 218 /* 219 * Handle all other files or directories the normal way. 220 */ 221 for (; i < findcn; i++) { 222 /* 223 * Stop with all reserved clusters, not just with EOF. 224 */ 225 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 226 goto hiteof; 227 byteoffset = FATOFS(pmp, cn); 228 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 229 if (bn != bp_bn) { 230 if (bp) 231 brelse(bp); 232 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 233 if (error) { 234 brelse(bp); 235 return (error); 236 } 237 bp_bn = bn; 238 } 239 prevcn = cn; 240 if (bo >= bsize) { 241 if (bp) 242 brelse(bp); 243 return (EIO); 244 } 245 if (FAT32(pmp)) 246 cn = getulong(&bp->b_data[bo]); 247 else 248 cn = getushort(&bp->b_data[bo]); 249 if (FAT12(pmp) && (prevcn & 1)) 250 cn >>= 4; 251 cn &= pmp->pm_fatmask; 252 253 /* 254 * Force the special cluster numbers 255 * to be the same for all cluster sizes 256 * to let the rest of msdosfs handle 257 * all cases the same. 258 */ 259 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 260 cn |= ~pmp->pm_fatmask; 261 } 262 263 if (!MSDOSFSEOF(pmp, cn)) { 264 if (bp) 265 brelse(bp); 266 if (bnp) 267 *bnp = cntobn(pmp, cn); 268 if (cnp) 269 *cnp = cn; 270 fc_setcache(dep, FC_LASTMAP, i, cn); 271 return (0); 272 } 273 274 hiteof:; 275 if (cnp) 276 *cnp = i; 277 if (bp) 278 brelse(bp); 279 /* update last file cluster entry in the fat cache */ 280 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 281 return (E2BIG); 282 } 283 284 /* 285 * Find the closest entry in the fat cache to the cluster we are looking 286 * for. 287 */ 288 static void 289 fc_lookup(dep, findcn, frcnp, fsrcnp) 290 struct denode *dep; 291 u_long findcn; 292 u_long *frcnp; 293 u_long *fsrcnp; 294 { 295 int i; 296 u_long cn; 297 struct fatcache *closest = 0; 298 299 for (i = 0; i < FC_SIZE; i++) { 300 cn = dep->de_fc[i].fc_frcn; 301 if (cn != FCE_EMPTY && cn <= findcn) { 302 if (closest == 0 || cn > closest->fc_frcn) 303 closest = &dep->de_fc[i]; 304 } 305 } 306 if (closest) { 307 *frcnp = closest->fc_frcn; 308 *fsrcnp = closest->fc_fsrcn; 309 } 310 } 311 312 /* 313 * Purge the fat cache in denode dep of all entries relating to file 314 * relative cluster frcn and beyond. 315 */ 316 void 317 fc_purge(dep, frcn) 318 struct denode *dep; 319 u_int frcn; 320 { 321 int i; 322 struct fatcache *fcp; 323 324 fcp = dep->de_fc; 325 for (i = 0; i < FC_SIZE; i++, fcp++) { 326 if (fcp->fc_frcn >= frcn) 327 fcp->fc_frcn = FCE_EMPTY; 328 } 329 } 330 331 /* 332 * Update the fat. 333 * If mirroring the fat, update all copies, with the first copy as last. 334 * Else update only the current fat (ignoring the others). 335 * 336 * pmp - msdosfsmount structure for filesystem to update 337 * bp - addr of modified fat block 338 * fatbn - block number relative to begin of filesystem of the modified fat block. 339 */ 340 static void 341 updatefats(pmp, bp, fatbn) 342 struct msdosfsmount *pmp; 343 struct buf *bp; 344 u_long fatbn; 345 { 346 int i; 347 struct buf *bpn; 348 349 #ifdef MSDOSFS_DEBUG 350 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 351 #endif 352 353 /* 354 * If we have an FSInfo block, update it. 355 */ 356 if (pmp->pm_fsinfo) { 357 u_long cn = pmp->pm_nxtfree; 358 359 if (pmp->pm_freeclustercount 360 && (pmp->pm_inusemap[cn / N_INUSEBITS] 361 & (1 << (cn % N_INUSEBITS)))) { 362 /* 363 * The cluster indicated in FSInfo isn't free 364 * any longer. Got get a new free one. 365 */ 366 for (cn = 0; cn < pmp->pm_maxcluster; cn += N_INUSEBITS) 367 if (pmp->pm_inusemap[cn / N_INUSEBITS] != (u_int)-1) 368 break; 369 pmp->pm_nxtfree = cn 370 + ffs(pmp->pm_inusemap[cn / N_INUSEBITS] 371 ^ (u_int)-1) - 1; 372 } 373 if (bread(pmp->pm_devvp, pmp->pm_fsinfo, fsi_size(pmp), 374 NOCRED, &bpn) != 0) { 375 /* 376 * Ignore the error, but turn off FSInfo update for the future. 377 */ 378 pmp->pm_fsinfo = 0; 379 brelse(bpn); 380 } else { 381 struct fsinfo *fp = (struct fsinfo *)bpn->b_data; 382 383 putulong(fp->fsinfree, pmp->pm_freeclustercount); 384 putulong(fp->fsinxtfree, pmp->pm_nxtfree); 385 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 386 bwrite(bpn); 387 else 388 bdwrite(bpn); 389 } 390 } 391 392 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 393 /* 394 * Now copy the block(s) of the modified fat to the other copies of 395 * the fat and write them out. This is faster than reading in the 396 * other fats and then writing them back out. This could tie up 397 * the fat for quite a while. Preventing others from accessing it. 398 * To prevent us from going after the fat quite so much we use 399 * delayed writes, unless they specfied "synchronous" when the 400 * filesystem was mounted. If synch is asked for then use 401 * bwrite()'s and really slow things down. 402 */ 403 for (i = 1; i < pmp->pm_FATs; i++) { 404 fatbn += pmp->pm_FATsecs; 405 /* getblk() never fails */ 406 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 407 0, 0, 0); 408 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 409 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 410 bwrite(bpn); 411 else 412 bdwrite(bpn); 413 } 414 } 415 416 /* 417 * Write out the first (or current) fat last. 418 */ 419 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 420 bwrite(bp); 421 else 422 bdwrite(bp); 423 /* 424 * Maybe update fsinfo sector here? 425 */ 426 } 427 428 /* 429 * Updating entries in 12 bit fats is a pain in the butt. 430 * 431 * The following picture shows where nibbles go when moving from a 12 bit 432 * cluster number into the appropriate bytes in the FAT. 433 * 434 * byte m byte m+1 byte m+2 435 * +----+----+ +----+----+ +----+----+ 436 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 437 * +----+----+ +----+----+ +----+----+ 438 * 439 * +----+----+----+ +----+----+----+ 440 * | 3 0 1 | | 4 5 2 | 441 * +----+----+----+ +----+----+----+ 442 * cluster n cluster n+1 443 * 444 * Where n is even. m = n + (n >> 2) 445 * 446 */ 447 static __inline void 448 usemap_alloc(pmp, cn) 449 struct msdosfsmount *pmp; 450 u_long cn; 451 { 452 453 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 454 pmp->pm_freeclustercount--; 455 } 456 457 static __inline void 458 usemap_free(pmp, cn) 459 struct msdosfsmount *pmp; 460 u_long cn; 461 { 462 463 pmp->pm_freeclustercount++; 464 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 465 } 466 467 int 468 clusterfree(pmp, cluster, oldcnp) 469 struct msdosfsmount *pmp; 470 u_long cluster; 471 u_long *oldcnp; 472 { 473 int error; 474 u_long oldcn; 475 476 usemap_free(pmp, cluster); 477 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 478 if (error) { 479 usemap_alloc(pmp, cluster); 480 return (error); 481 } 482 /* 483 * If the cluster was successfully marked free, then update 484 * the count of free clusters, and turn off the "allocated" 485 * bit in the "in use" cluster bit map. 486 */ 487 if (oldcnp) 488 *oldcnp = oldcn; 489 return (0); 490 } 491 492 /* 493 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 494 * 495 * function - whether to get or set a fat entry 496 * pmp - address of the msdosfsmount structure for the filesystem 497 * whose fat is to be manipulated. 498 * cn - which cluster is of interest 499 * oldcontents - address of a word that is to receive the contents of the 500 * cluster'th entry if this is a get function 501 * newcontents - the new value to be written into the cluster'th element of 502 * the fat if this is a set function. 503 * 504 * This function can also be used to free a cluster by setting the fat entry 505 * for a cluster to 0. 506 * 507 * All copies of the fat are updated if this is a set function. NOTE: If 508 * fatentry() marks a cluster as free it does not update the inusemap in 509 * the msdosfsmount structure. This is left to the caller. 510 */ 511 int 512 fatentry(function, pmp, cn, oldcontents, newcontents) 513 int function; 514 struct msdosfsmount *pmp; 515 u_long cn; 516 u_long *oldcontents; 517 u_long newcontents; 518 { 519 int error; 520 u_long readcn; 521 u_long bn, bo, bsize, byteoffset; 522 struct buf *bp; 523 524 #ifdef MSDOSFS_DEBUG 525 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 526 function, pmp, cn, oldcontents, newcontents); 527 #endif 528 529 #ifdef DIAGNOSTIC 530 /* 531 * Be sure they asked us to do something. 532 */ 533 if ((function & (FAT_SET | FAT_GET)) == 0) { 534 printf("fatentry(): function code doesn't specify get or set\n"); 535 return (EINVAL); 536 } 537 538 /* 539 * If they asked us to return a cluster number but didn't tell us 540 * where to put it, give them an error. 541 */ 542 if ((function & FAT_GET) && oldcontents == NULL) { 543 printf("fatentry(): get function with no place to put result\n"); 544 return (EINVAL); 545 } 546 #endif 547 548 /* 549 * Be sure the requested cluster is in the filesystem. 550 */ 551 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 552 return (EINVAL); 553 554 byteoffset = FATOFS(pmp, cn); 555 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 556 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 557 if (error) { 558 brelse(bp); 559 return (error); 560 } 561 562 if (function & FAT_GET) { 563 if (FAT32(pmp)) 564 readcn = getulong(&bp->b_data[bo]); 565 else 566 readcn = getushort(&bp->b_data[bo]); 567 if (FAT12(pmp) & (cn & 1)) 568 readcn >>= 4; 569 readcn &= pmp->pm_fatmask; 570 /* map reserved fat entries to same values for all fats */ 571 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 572 readcn |= ~pmp->pm_fatmask; 573 *oldcontents = readcn; 574 } 575 if (function & FAT_SET) { 576 switch (pmp->pm_fatmask) { 577 case FAT12_MASK: 578 readcn = getushort(&bp->b_data[bo]); 579 if (cn & 1) { 580 readcn &= 0x000f; 581 readcn |= newcontents << 4; 582 } else { 583 readcn &= 0xf000; 584 readcn |= newcontents & 0xfff; 585 } 586 putushort(&bp->b_data[bo], readcn); 587 break; 588 case FAT16_MASK: 589 putushort(&bp->b_data[bo], newcontents); 590 break; 591 case FAT32_MASK: 592 /* 593 * According to spec we have to retain the 594 * high order bits of the fat entry. 595 */ 596 readcn = getulong(&bp->b_data[bo]); 597 readcn &= ~FAT32_MASK; 598 readcn |= newcontents & FAT32_MASK; 599 putulong(&bp->b_data[bo], readcn); 600 break; 601 } 602 updatefats(pmp, bp, bn); 603 bp = NULL; 604 pmp->pm_fmod = 1; 605 } 606 if (bp) 607 brelse(bp); 608 return (0); 609 } 610 611 /* 612 * Update a contiguous cluster chain 613 * 614 * pmp - mount point 615 * start - first cluster of chain 616 * count - number of clusters in chain 617 * fillwith - what to write into fat entry of last cluster 618 */ 619 static int 620 fatchain(pmp, start, count, fillwith) 621 struct msdosfsmount *pmp; 622 u_long start; 623 u_long count; 624 u_long fillwith; 625 { 626 int error; 627 u_long bn, bo, bsize, byteoffset, readcn, newc; 628 struct buf *bp; 629 630 #ifdef MSDOSFS_DEBUG 631 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 632 pmp, start, count, fillwith); 633 #endif 634 /* 635 * Be sure the clusters are in the filesystem. 636 */ 637 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 638 return (EINVAL); 639 640 while (count > 0) { 641 byteoffset = FATOFS(pmp, start); 642 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 643 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 644 if (error) { 645 brelse(bp); 646 return (error); 647 } 648 while (count > 0) { 649 start++; 650 newc = --count > 0 ? start : fillwith; 651 switch (pmp->pm_fatmask) { 652 case FAT12_MASK: 653 readcn = getushort(&bp->b_data[bo]); 654 if (start & 1) { 655 readcn &= 0xf000; 656 readcn |= newc & 0xfff; 657 } else { 658 readcn &= 0x000f; 659 readcn |= newc << 4; 660 } 661 putushort(&bp->b_data[bo], readcn); 662 bo++; 663 if (!(start & 1)) 664 bo++; 665 break; 666 case FAT16_MASK: 667 putushort(&bp->b_data[bo], newc); 668 bo += 2; 669 break; 670 case FAT32_MASK: 671 readcn = getulong(&bp->b_data[bo]); 672 readcn &= ~pmp->pm_fatmask; 673 readcn |= newc & pmp->pm_fatmask; 674 putulong(&bp->b_data[bo], readcn); 675 bo += 4; 676 break; 677 } 678 if (bo >= bsize) 679 break; 680 } 681 updatefats(pmp, bp, bn); 682 } 683 pmp->pm_fmod = 1; 684 return (0); 685 } 686 687 /* 688 * Check the length of a free cluster chain starting at start. 689 * 690 * pmp - mount point 691 * start - start of chain 692 * count - maximum interesting length 693 */ 694 static int 695 chainlength(pmp, start, count) 696 struct msdosfsmount *pmp; 697 u_long start; 698 u_long count; 699 { 700 u_long idx, max_idx; 701 u_int map; 702 u_long len; 703 704 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 705 idx = start / N_INUSEBITS; 706 start %= N_INUSEBITS; 707 map = pmp->pm_inusemap[idx]; 708 map &= ~((1 << start) - 1); 709 if (map) { 710 len = ffs(map) - 1 - start; 711 return (len > count ? count : len); 712 } 713 len = N_INUSEBITS - start; 714 if (len >= count) 715 return (count); 716 while (++idx <= max_idx) { 717 if (len >= count) 718 break; 719 map = pmp->pm_inusemap[idx]; 720 if (map) { 721 len += ffs(map) - 1; 722 break; 723 } 724 len += N_INUSEBITS; 725 } 726 return (len > count ? count : len); 727 } 728 729 /* 730 * Allocate contigous free clusters. 731 * 732 * pmp - mount point. 733 * start - start of cluster chain. 734 * count - number of clusters to allocate. 735 * fillwith - put this value into the fat entry for the 736 * last allocated cluster. 737 * retcluster - put the first allocated cluster's number here. 738 * got - how many clusters were actually allocated. 739 */ 740 static int 741 chainalloc(pmp, start, count, fillwith, retcluster, got) 742 struct msdosfsmount *pmp; 743 u_long start; 744 u_long count; 745 u_long fillwith; 746 u_long *retcluster; 747 u_long *got; 748 { 749 int error; 750 u_long cl, n; 751 752 for (cl = start, n = count; n-- > 0;) 753 usemap_alloc(pmp, cl++); 754 755 error = fatchain(pmp, start, count, fillwith); 756 if (error != 0) 757 return (error); 758 #ifdef MSDOSFS_DEBUG 759 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 760 start, count); 761 #endif 762 if (retcluster) 763 *retcluster = start; 764 if (got) 765 *got = count; 766 return (0); 767 } 768 769 /* 770 * Allocate contiguous free clusters. 771 * 772 * pmp - mount point. 773 * start - preferred start of cluster chain. 774 * count - number of clusters requested. 775 * fillwith - put this value into the fat entry for the 776 * last allocated cluster. 777 * retcluster - put the first allocated cluster's number here. 778 * got - how many clusters were actually allocated. 779 */ 780 int 781 clusteralloc(pmp, start, count, fillwith, retcluster, got) 782 struct msdosfsmount *pmp; 783 u_long start; 784 u_long count; 785 u_long fillwith; 786 u_long *retcluster; 787 u_long *got; 788 { 789 u_long idx; 790 u_long len, newst, foundl, cn, l; 791 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 792 u_int map; 793 794 #ifdef MSDOSFS_DEBUG 795 printf("clusteralloc(): find %lu clusters\n",count); 796 #endif 797 if (start) { 798 if ((len = chainlength(pmp, start, count)) >= count) 799 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 800 } else 801 len = 0; 802 803 /* 804 * Start at a (pseudo) random place to maximize cluster runs 805 * under multiple writers. 806 */ 807 newst = random() % (pmp->pm_maxcluster + 1); 808 foundl = 0; 809 810 for (cn = newst; cn <= pmp->pm_maxcluster;) { 811 idx = cn / N_INUSEBITS; 812 map = pmp->pm_inusemap[idx]; 813 map |= (1 << (cn % N_INUSEBITS)) - 1; 814 if (map != (u_int)-1) { 815 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 816 if ((l = chainlength(pmp, cn, count)) >= count) 817 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 818 if (l > foundl) { 819 foundcn = cn; 820 foundl = l; 821 } 822 cn += l + 1; 823 continue; 824 } 825 cn += N_INUSEBITS - cn % N_INUSEBITS; 826 } 827 for (cn = 0; cn < newst;) { 828 idx = cn / N_INUSEBITS; 829 map = pmp->pm_inusemap[idx]; 830 map |= (1 << (cn % N_INUSEBITS)) - 1; 831 if (map != (u_int)-1) { 832 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 833 if ((l = chainlength(pmp, cn, count)) >= count) 834 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 835 if (l > foundl) { 836 foundcn = cn; 837 foundl = l; 838 } 839 cn += l + 1; 840 continue; 841 } 842 cn += N_INUSEBITS - cn % N_INUSEBITS; 843 } 844 845 if (!foundl) 846 return (ENOSPC); 847 848 if (len) 849 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 850 else 851 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 852 } 853 854 855 /* 856 * Free a chain of clusters. 857 * 858 * pmp - address of the msdosfs mount structure for the filesystem 859 * containing the cluster chain to be freed. 860 * startcluster - number of the 1st cluster in the chain of clusters to be 861 * freed. 862 */ 863 int 864 freeclusterchain(pmp, cluster) 865 struct msdosfsmount *pmp; 866 u_long cluster; 867 { 868 int error; 869 struct buf *bp = NULL; 870 u_long bn, bo, bsize, byteoffset; 871 u_long readcn, lbn = -1; 872 873 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 874 byteoffset = FATOFS(pmp, cluster); 875 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 876 if (lbn != bn) { 877 if (bp) 878 updatefats(pmp, bp, lbn); 879 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 880 if (error) { 881 brelse(bp); 882 return (error); 883 } 884 lbn = bn; 885 } 886 usemap_free(pmp, cluster); 887 switch (pmp->pm_fatmask) { 888 case FAT12_MASK: 889 readcn = getushort(&bp->b_data[bo]); 890 if (cluster & 1) { 891 cluster = readcn >> 4; 892 readcn &= 0x000f; 893 readcn |= MSDOSFSFREE << 4; 894 } else { 895 cluster = readcn; 896 readcn &= 0xf000; 897 readcn |= MSDOSFSFREE & 0xfff; 898 } 899 putushort(&bp->b_data[bo], readcn); 900 break; 901 case FAT16_MASK: 902 cluster = getushort(&bp->b_data[bo]); 903 putushort(&bp->b_data[bo], MSDOSFSFREE); 904 break; 905 case FAT32_MASK: 906 cluster = getulong(&bp->b_data[bo]); 907 putulong(&bp->b_data[bo], 908 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 909 break; 910 } 911 cluster &= pmp->pm_fatmask; 912 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 913 cluster |= pmp->pm_fatmask; 914 } 915 if (bp) 916 updatefats(pmp, bp, bn); 917 return (0); 918 } 919 920 /* 921 * Read in fat blocks looking for free clusters. For every free cluster 922 * found turn off its corresponding bit in the pm_inusemap. 923 */ 924 int 925 fillinusemap(pmp) 926 struct msdosfsmount *pmp; 927 { 928 struct buf *bp = NULL; 929 u_long cn, readcn; 930 int error; 931 u_long bn, bo, bsize, byteoffset; 932 933 /* 934 * Mark all clusters in use, we mark the free ones in the fat scan 935 * loop further down. 936 */ 937 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 938 pmp->pm_inusemap[cn] = (u_int)-1; 939 940 /* 941 * Figure how many free clusters are in the filesystem by ripping 942 * through the fat counting the number of entries whose content is 943 * zero. These represent free clusters. 944 */ 945 pmp->pm_freeclustercount = 0; 946 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 947 byteoffset = FATOFS(pmp, cn); 948 bo = byteoffset % pmp->pm_fatblocksize; 949 if (!bo || !bp) { 950 /* Read new FAT block */ 951 if (bp) 952 brelse(bp); 953 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 954 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 955 if (error) { 956 brelse(bp); 957 return (error); 958 } 959 } 960 if (FAT32(pmp)) 961 readcn = getulong(&bp->b_data[bo]); 962 else 963 readcn = getushort(&bp->b_data[bo]); 964 if (FAT12(pmp) && (cn & 1)) 965 readcn >>= 4; 966 readcn &= pmp->pm_fatmask; 967 968 if (readcn == 0) 969 usemap_free(pmp, cn); 970 } 971 brelse(bp); 972 return (0); 973 } 974 975 /* 976 * Allocate a new cluster and chain it onto the end of the file. 977 * 978 * dep - the file to extend 979 * count - number of clusters to allocate 980 * bpp - where to return the address of the buf header for the first new 981 * file block 982 * ncp - where to put cluster number of the first newly allocated cluster 983 * If this pointer is 0, do not return the cluster number. 984 * flags - see fat.h 985 * 986 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 987 * the de_flag field of the denode and it does not change the de_FileSize 988 * field. This is left for the caller to do. 989 */ 990 int 991 extendfile(dep, count, bpp, ncp, flags) 992 struct denode *dep; 993 u_long count; 994 struct buf **bpp; 995 u_long *ncp; 996 int flags; 997 { 998 int error; 999 u_long frcn; 1000 u_long cn, got; 1001 struct msdosfsmount *pmp = dep->de_pmp; 1002 struct buf *bp; 1003 daddr_t blkno; 1004 1005 /* 1006 * Don't try to extend the root directory 1007 */ 1008 if (dep->de_StartCluster == MSDOSFSROOT 1009 && (dep->de_Attributes & ATTR_DIRECTORY)) { 1010 printf("extendfile(): attempt to extend root directory\n"); 1011 return (ENOSPC); 1012 } 1013 1014 /* 1015 * If the "file's last cluster" cache entry is empty, and the file 1016 * is not empty, then fill the cache entry by calling pcbmap(). 1017 */ 1018 fc_fileextends++; 1019 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 1020 dep->de_StartCluster != 0) { 1021 fc_lfcempty++; 1022 error = pcbmap(dep, 0xffff, 0, &cn, 0); 1023 /* we expect it to return E2BIG */ 1024 if (error != E2BIG) 1025 return (error); 1026 } 1027 1028 while (count > 0) { 1029 /* 1030 * Allocate a new cluster chain and cat onto the end of the 1031 * file. * If the file is empty we make de_StartCluster point 1032 * to the new block. Note that de_StartCluster being 0 is 1033 * sufficient to be sure the file is empty since we exclude 1034 * attempts to extend the root directory above, and the root 1035 * dir is the only file with a startcluster of 0 that has 1036 * blocks allocated (sort of). 1037 */ 1038 if (dep->de_StartCluster == 0) 1039 cn = 0; 1040 else 1041 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1042 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1043 if (error) 1044 return (error); 1045 1046 count -= got; 1047 1048 /* 1049 * Give them the filesystem relative cluster number if they want 1050 * it. 1051 */ 1052 if (ncp) { 1053 *ncp = cn; 1054 ncp = NULL; 1055 } 1056 1057 if (dep->de_StartCluster == 0) { 1058 dep->de_StartCluster = cn; 1059 frcn = 0; 1060 } else { 1061 error = fatentry(FAT_SET, pmp, 1062 dep->de_fc[FC_LASTFC].fc_fsrcn, 1063 0, cn); 1064 if (error) { 1065 clusterfree(pmp, cn, NULL); 1066 return (error); 1067 } 1068 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1069 } 1070 1071 /* 1072 * Update the "last cluster of the file" entry in the denode's fat 1073 * cache. 1074 */ 1075 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1076 1077 if (flags & DE_CLEAR) { 1078 while (got-- > 0) { 1079 /* 1080 * Get the buf header for the new block of the file. 1081 */ 1082 if (dep->de_Attributes & ATTR_DIRECTORY) 1083 bp = getblk(pmp->pm_devvp, 1084 cntobn(pmp, cn++), 1085 pmp->pm_bpcluster, 0, 0, 0); 1086 else { 1087 bp = getblk(DETOV(dep), 1088 de_cn2bn(pmp, frcn++), 1089 pmp->pm_bpcluster, 0, 0, 0); 1090 /* 1091 * Do the bmap now, as in msdosfs_write 1092 */ 1093 if (pcbmap(dep, 1094 de_bn2cn(pmp, bp->b_lblkno), 1095 &blkno, 0, 0)) 1096 bp->b_blkno = -1; 1097 if (bp->b_blkno == -1) 1098 panic("extendfile: pcbmap"); 1099 else 1100 bp->b_blkno = blkno; 1101 } 1102 clrbuf(bp); 1103 if (bpp) { 1104 *bpp = bp; 1105 bpp = NULL; 1106 } else 1107 bdwrite(bp); 1108 } 1109 } 1110 } 1111 1112 return (0); 1113 } 1114 1115 /*- 1116 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1117 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1118 * this bit is not defined for FAT12 volumes, which are always assumed to 1119 * be dirty. 1120 * 1121 * The fatentry() routine only works on cluster numbers that a file could 1122 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1123 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1124 * 1125 * Inputs: 1126 * pmp The MS-DOS volume to mark 1127 * dirty Non-zero if the volume should be marked dirty; zero if it 1128 * should be marked clean 1129 * 1130 * Result: 1131 * 0 Success 1132 * EROFS Volume is read-only 1133 * ? (other errors from called routines) 1134 */ 1135 int 1136 markvoldirty(struct msdosfsmount *pmp, int dirty) 1137 { 1138 struct buf *bp; 1139 u_long bn, bo, bsize, byteoffset, fatval; 1140 int error; 1141 1142 /* 1143 * FAT12 does not support a "clean" bit, so don't do anything for 1144 * FAT12. 1145 */ 1146 if (FAT12(pmp)) 1147 return (0); 1148 1149 /* Can't change the bit on a read-only filesystem. */ 1150 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1151 return (EROFS); 1152 1153 /* 1154 * Fetch the block containing the FAT entry. It is given by the 1155 * pseudo-cluster 1. 1156 */ 1157 byteoffset = FATOFS(pmp, 1); 1158 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1159 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1160 if (error) { 1161 brelse(bp); 1162 return (error); 1163 } 1164 1165 /* 1166 * Get the current value of the FAT entry and set/clear the relevant 1167 * bit. Dirty means clear the "clean" bit; clean means set the 1168 * "clean" bit. 1169 */ 1170 if (FAT32(pmp)) { 1171 /* FAT32 uses bit 27. */ 1172 fatval = getulong(&bp->b_data[bo]); 1173 if (dirty) 1174 fatval &= 0xF7FFFFFF; 1175 else 1176 fatval |= 0x08000000; 1177 putulong(&bp->b_data[bo], fatval); 1178 } else { 1179 /* Must be FAT16; use bit 15. */ 1180 fatval = getushort(&bp->b_data[bo]); 1181 if (dirty) 1182 fatval &= 0x7FFF; 1183 else 1184 fatval |= 0x8000; 1185 putushort(&bp->b_data[bo], fatval); 1186 } 1187 1188 /* Write out the modified FAT block synchronously. */ 1189 return (bwrite(bp)); 1190 }
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