1 /* $OpenBSD: msdosfs_fat.c,v 1.8 1999/01/10 21:50:32 art Exp $ */ 2 /* $NetBSD: msdosfs_fat.c,v 1.26 1997/10/17 11:24:02 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/buf.h> 57 #include <sys/file.h> 58 #include <sys/namei.h> 59 #include <sys/mount.h> /* to define statfs structure */ 60 #include <sys/vnode.h> /* to define vattr structure */ 61 #include <sys/errno.h> 62 #include <sys/dirent.h> 63 64 /* 65 * msdosfs include files. 66 */ 67 #include <msdosfs/bpb.h> 68 #include <msdosfs/msdosfsmount.h> 69 #include <msdosfs/direntry.h> 70 #include <msdosfs/denode.h> 71 #include <msdosfs/fat.h> 72 73 /* 74 * Fat cache stats. 75 */ 76 int fc_fileextends; /* # of file extends */ 77 int fc_lfcempty; /* # of time last file cluster cache entry 78 * was empty */ 79 int fc_bmapcalls; /* # of times pcbmap was called */ 80 81 #define LMMAX 20 82 int fc_lmdistance[LMMAX]; /* counters for how far off the last 83 * cluster mapped entry was. */ 84 int fc_largedistance; /* off by more than LMMAX */ 85 86 static void fatblock __P((struct msdosfsmount *, u_long, u_long *, u_long *, 87 u_long *)); 88 void updatefats __P((struct msdosfsmount *, struct buf *, u_long)); 89 static __inline void usemap_free __P((struct msdosfsmount *, u_long)); 90 static __inline void usemap_alloc __P((struct msdosfsmount *, u_long)); 91 static int fatchain __P((struct msdosfsmount *, u_long, u_long, u_long)); 92 int chainlength __P((struct msdosfsmount *, u_long, u_long)); 93 int chainalloc __P((struct msdosfsmount *, u_long, u_long, u_long, u_long *, 94 u_long *)); 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 * pmp->pm_BytesPerSec; 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 } 118 119 /* 120 * Map the logical cluster number of a file into a physical disk sector 121 * that is filesystem relative. 122 * 123 * dep - address of denode representing the file of interest 124 * findcn - file relative cluster whose filesystem relative cluster number 125 * and/or block number are/is to be found 126 * bnp - address of where to place the file system relative block number. 127 * If this pointer is null then don't return this quantity. 128 * cnp - address of where to place the file system relative cluster number. 129 * If this pointer is null then don't return this quantity. 130 * 131 * NOTE: Either bnp or cnp must be non-null. 132 * This function has one side effect. If the requested file relative cluster 133 * is beyond the end of file, then the actual number of clusters in the file 134 * is returned in *cnp. This is useful for determining how long a directory is. 135 * If cnp is null, nothing is returned. 136 */ 137 int 138 pcbmap(dep, findcn, bnp, cnp, sp) 139 struct denode *dep; 140 u_long findcn; /* file relative cluster to get */ 141 daddr_t *bnp; /* returned filesys relative blk number */ 142 u_long *cnp; /* returned cluster number */ 143 int *sp; /* returned block size */ 144 { 145 int error; 146 u_long i; 147 u_long cn; 148 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 149 u_long byteoffset; 150 u_long bn; 151 u_long bo; 152 struct buf *bp = NULL; 153 u_long bp_bn = -1; 154 struct msdosfsmount *pmp = dep->de_pmp; 155 u_long bsize; 156 157 fc_bmapcalls++; 158 159 /* 160 * If they don't give us someplace to return a value then don't 161 * bother doing anything. 162 */ 163 if (bnp == NULL && cnp == NULL && sp == NULL) 164 return (0); 165 166 cn = dep->de_StartCluster; 167 /* 168 * The "file" that makes up the root directory is contiguous, 169 * permanently allocated, of fixed size, and is not made up of 170 * clusters. If the cluster number is beyond the end of the root 171 * directory, then return the number of clusters in the file. 172 */ 173 if (cn == MSDOSFSROOT) { 174 if (dep->de_Attributes & ATTR_DIRECTORY) { 175 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 176 if (cnp) 177 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 178 return (E2BIG); 179 } 180 if (bnp) 181 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 182 if (cnp) 183 *cnp = MSDOSFSROOT; 184 if (sp) 185 *sp = min(pmp->pm_bpcluster, 186 dep->de_FileSize - de_cn2off(pmp, findcn)); 187 return (0); 188 } else { /* just an empty file */ 189 if (cnp) 190 *cnp = 0; 191 return (E2BIG); 192 } 193 } 194 195 /* 196 * All other files do I/O in cluster sized blocks 197 */ 198 if (sp) 199 *sp = pmp->pm_bpcluster; 200 201 /* 202 * Rummage around in the fat cache, maybe we can avoid tromping 203 * thru every fat entry for the file. And, keep track of how far 204 * off the cache was from where we wanted to be. 205 */ 206 i = 0; 207 fc_lookup(dep, findcn, &i, &cn); 208 if ((bn = findcn - i) >= LMMAX) 209 fc_largedistance++; 210 else 211 fc_lmdistance[bn]++; 212 213 /* 214 * Handle all other files or directories the normal way. 215 */ 216 for (; i < findcn; i++) { 217 /* 218 * Stop with all reserved clusters, not just with EOF. 219 */ 220 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 221 goto hiteof; 222 byteoffset = FATOFS(pmp, cn); 223 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 224 if (bn != bp_bn) { 225 if (bp) 226 brelse(bp); 227 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 228 if (error) { 229 brelse(bp); 230 return (error); 231 } 232 bp_bn = bn; 233 } 234 prevcn = cn; 235 if (FAT32(pmp)) 236 cn = getulong(&bp->b_data[bo]); 237 else 238 cn = getushort(&bp->b_data[bo]); 239 if (FAT12(pmp) && (prevcn & 1)) 240 cn >>= 4; 241 cn &= pmp->pm_fatmask; 242 243 /* 244 * Force the special cluster numbers 245 * to be the same for all cluster sizes 246 * to let the rest of msdosfs handle 247 * all cases the same. 248 */ 249 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 250 cn |= ~pmp->pm_fatmask; 251 } 252 253 if (!MSDOSFSEOF(pmp, cn)) { 254 if (bp) 255 brelse(bp); 256 if (bnp) 257 *bnp = cntobn(pmp, cn); 258 if (cnp) 259 *cnp = cn; 260 fc_setcache(dep, FC_LASTMAP, i, cn); 261 return (0); 262 } 263 264 hiteof:; 265 if (cnp) 266 *cnp = i; 267 if (bp) 268 brelse(bp); 269 /* update last file cluster entry in the fat cache */ 270 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 271 return (E2BIG); 272 } 273 274 /* 275 * Find the closest entry in the fat cache to the cluster we are looking 276 * for. 277 */ 278 void 279 fc_lookup(dep, findcn, frcnp, fsrcnp) 280 struct denode *dep; 281 u_long findcn; 282 u_long *frcnp; 283 u_long *fsrcnp; 284 { 285 int i; 286 u_long cn; 287 struct fatcache *closest = 0; 288 289 for (i = 0; i < FC_SIZE; i++) { 290 cn = dep->de_fc[i].fc_frcn; 291 if (cn != FCE_EMPTY && cn <= findcn) { 292 if (closest == 0 || cn > closest->fc_frcn) 293 closest = &dep->de_fc[i]; 294 } 295 } 296 if (closest) { 297 *frcnp = closest->fc_frcn; 298 *fsrcnp = closest->fc_fsrcn; 299 } 300 } 301 302 /* 303 * Purge the fat cache in denode dep of all entries relating to file 304 * relative cluster frcn and beyond. 305 */ 306 void 307 fc_purge(dep, frcn) 308 struct denode *dep; 309 u_int frcn; 310 { 311 int i; 312 struct fatcache *fcp; 313 314 fcp = dep->de_fc; 315 for (i = 0; i < FC_SIZE; i++, fcp++) { 316 if (fcp->fc_frcn >= frcn) 317 fcp->fc_frcn = FCE_EMPTY; 318 } 319 } 320 321 /* 322 * Update the fat. 323 * If mirroring the fat, update all copies, with the first copy as last. 324 * Else update only the current fat (ignoring the others). 325 * 326 * pmp - msdosfsmount structure for filesystem to update 327 * bp - addr of modified fat block 328 * fatbn - block number relative to begin of filesystem of the modified fat block. 329 */ 330 void 331 updatefats(pmp, bp, fatbn) 332 struct msdosfsmount *pmp; 333 struct buf *bp; 334 u_long fatbn; 335 { 336 int i; 337 struct buf *bpn; 338 339 #ifdef MSDOSFS_DEBUG 340 printf("updatefats(pmp %08, buf %x, fatbn %ld)\n", pmp, bp, fatbn); 341 #endif 342 343 /* 344 * If we have an FSInfo block, update it. 345 */ 346 if (pmp->pm_fsinfo) { 347 u_long cn = pmp->pm_nxtfree; 348 349 if (pmp->pm_freeclustercount 350 && (pmp->pm_inusemap[cn / N_INUSEBITS] 351 & (1 << (cn % N_INUSEBITS)))) { 352 /* 353 * The cluster indicated in FSInfo isn't free 354 * any longer. Got get a new free one. 355 */ 356 for (cn = 0; cn < pmp->pm_maxcluster; cn++) 357 if (pmp->pm_inusemap[cn / N_INUSEBITS] != (u_int)-1) 358 break; 359 pmp->pm_nxtfree = cn 360 + ffs(pmp->pm_inusemap[cn / N_INUSEBITS] 361 ^ (u_int)-1) - 1; 362 } 363 if (bread(pmp->pm_devvp, pmp->pm_fsinfo, 1024, NOCRED, &bpn) != 0) { 364 /* 365 * Ignore the error, but turn off FSInfo update for the future. 366 */ 367 pmp->pm_fsinfo = 0; 368 brelse(bpn); 369 } else { 370 struct fsinfo *fp = (struct fsinfo *)bpn->b_data; 371 372 putulong(fp->fsinfree, pmp->pm_freeclustercount); 373 putulong(fp->fsinxtfree, pmp->pm_nxtfree); 374 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 375 bwrite(bpn); 376 else 377 bdwrite(bpn); 378 } 379 } 380 381 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 382 /* 383 * Now copy the block(s) of the modified fat to the other copies of 384 * the fat and write them out. This is faster than reading in the 385 * other fats and then writing them back out. This could tie up 386 * the fat for quite a while. Preventing others from accessing it. 387 * To prevent us from going after the fat quite so much we use 388 * delayed writes, unless they specfied "synchronous" when the 389 * filesystem was mounted. If synch is asked for then use 390 * bwrite()'s and really slow things down. 391 */ 392 for (i = 1; i < pmp->pm_FATs; i++) { 393 fatbn += pmp->pm_FATsecs; 394 /* getblk() never fails */ 395 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 0, 0); 396 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 397 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 398 bwrite(bpn); 399 else 400 bdwrite(bpn); 401 } 402 } 403 404 /* 405 * Write out the first (or current) fat last. 406 */ 407 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 408 bwrite(bp); 409 else 410 bdwrite(bp); 411 /* 412 * Maybe update fsinfo sector here? 413 */ 414 } 415 416 /* 417 * Updating entries in 12 bit fats is a pain in the butt. 418 * 419 * The following picture shows where nibbles go when moving from a 12 bit 420 * cluster number into the appropriate bytes in the FAT. 421 * 422 * byte m byte m+1 byte m+2 423 * +----+----+ +----+----+ +----+----+ 424 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 425 * +----+----+ +----+----+ +----+----+ 426 * 427 * +----+----+----+ +----+----+----+ 428 * | 3 0 1 | | 4 5 2 | 429 * +----+----+----+ +----+----+----+ 430 * cluster n cluster n+1 431 * 432 * Where n is even. m = n + (n >> 2) 433 * 434 */ 435 static __inline void 436 usemap_alloc(pmp, cn) 437 struct msdosfsmount *pmp; 438 u_long cn; 439 { 440 441 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 442 pmp->pm_freeclustercount--; 443 } 444 445 static __inline void 446 usemap_free(pmp, cn) 447 struct msdosfsmount *pmp; 448 u_long cn; 449 { 450 451 pmp->pm_freeclustercount++; 452 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 453 } 454 455 int 456 clusterfree(pmp, cluster, oldcnp) 457 struct msdosfsmount *pmp; 458 u_long cluster; 459 u_long *oldcnp; 460 { 461 int error; 462 u_long oldcn; 463 464 usemap_free(pmp, cluster); 465 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 466 if (error) { 467 usemap_alloc(pmp, cluster); 468 return (error); 469 } 470 /* 471 * If the cluster was successfully marked free, then update 472 * the count of free clusters, and turn off the "allocated" 473 * bit in the "in use" cluster bit map. 474 */ 475 if (oldcnp) 476 *oldcnp = oldcn; 477 return (0); 478 } 479 480 /* 481 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 482 * 483 * function - whether to get or set a fat entry 484 * pmp - address of the msdosfsmount structure for the filesystem 485 * whose fat is to be manipulated. 486 * cn - which cluster is of interest 487 * oldcontents - address of a word that is to receive the contents of the 488 * cluster'th entry if this is a get function 489 * newcontents - the new value to be written into the cluster'th element of 490 * the fat if this is a set function. 491 * 492 * This function can also be used to free a cluster by setting the fat entry 493 * for a cluster to 0. 494 * 495 * All copies of the fat are updated if this is a set function. NOTE: If 496 * fatentry() marks a cluster as free it does not update the inusemap in 497 * the msdosfsmount structure. This is left to the caller. 498 */ 499 int 500 fatentry(function, pmp, cn, oldcontents, newcontents) 501 int function; 502 struct msdosfsmount *pmp; 503 u_long cn; 504 u_long *oldcontents; 505 u_long newcontents; 506 { 507 int error; 508 u_long readcn; 509 u_long bn, bo, bsize, byteoffset; 510 struct buf *bp; 511 512 #ifdef MSDOSFS_DEBUG 513 printf("fatentry(func %d, pmp %08x, clust %d, oldcon %08x, newcon %d)\n", 514 function, pmp, cn, oldcontents, newcontents); 515 #endif 516 517 #ifdef DIAGNOSTIC 518 /* 519 * Be sure they asked us to do something. 520 */ 521 if ((function & (FAT_SET | FAT_GET)) == 0) { 522 printf("fatentry(): function code doesn't specify get or set\n"); 523 return (EINVAL); 524 } 525 526 /* 527 * If they asked us to return a cluster number but didn't tell us 528 * where to put it, give them an error. 529 */ 530 if ((function & FAT_GET) && oldcontents == NULL) { 531 printf("fatentry(): get function with no place to put result\n"); 532 return (EINVAL); 533 } 534 #endif 535 536 /* 537 * Be sure the requested cluster is in the filesystem. 538 */ 539 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 540 return (EINVAL); 541 542 byteoffset = FATOFS(pmp, cn); 543 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 544 if ((error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp)) != 0) { 545 brelse(bp); 546 return (error); 547 } 548 549 if (function & FAT_GET) { 550 if (FAT32(pmp)) 551 readcn = getulong(&bp->b_data[bo]); 552 else 553 readcn = getushort(&bp->b_data[bo]); 554 if (FAT12(pmp) && (cn & 1)) 555 readcn >>= 4; 556 readcn &= pmp->pm_fatmask; 557 /* map reserved fat entries to same values for all fats */ 558 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 559 readcn |= ~pmp->pm_fatmask; 560 *oldcontents = readcn; 561 } 562 if (function & FAT_SET) { 563 switch (pmp->pm_fatmask) { 564 case FAT12_MASK: 565 readcn = getushort(&bp->b_data[bo]); 566 if (cn & 1) { 567 readcn &= 0x000f; 568 readcn |= newcontents << 4; 569 } else { 570 readcn &= 0xf000; 571 readcn |= newcontents & 0xfff; 572 } 573 putushort(&bp->b_data[bo], readcn); 574 break; 575 case FAT16_MASK: 576 putushort(&bp->b_data[bo], newcontents); 577 break; 578 case FAT32_MASK: 579 /* 580 * According to spec we have to retain the 581 * high order bits of the fat entry. 582 */ 583 readcn = getulong(&bp->b_data[bo]); 584 readcn &= ~FAT32_MASK; 585 readcn |= newcontents & FAT32_MASK; 586 putulong(&bp->b_data[bo], readcn); 587 break; 588 } 589 updatefats(pmp, bp, bn); 590 bp = NULL; 591 pmp->pm_fmod = 1; 592 } 593 if (bp) 594 brelse(bp); 595 return (0); 596 } 597 598 /* 599 * Update a contiguous cluster chain 600 * 601 * pmp - mount point 602 * start - first cluster of chain 603 * count - number of clusters in chain 604 * fillwith - what to write into fat entry of last cluster 605 */ 606 static int 607 fatchain(pmp, start, count, fillwith) 608 struct msdosfsmount *pmp; 609 u_long start; 610 u_long count; 611 u_long fillwith; 612 { 613 int error; 614 u_long bn, bo, bsize, byteoffset, readcn, newc; 615 struct buf *bp; 616 617 #ifdef MSDOSFS_DEBUG 618 printf("fatchain(pmp %08x, start %d, count %d, fillwith %d)\n", 619 pmp, start, count, fillwith); 620 #endif 621 /* 622 * Be sure the clusters are in the filesystem. 623 */ 624 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 625 return (EINVAL); 626 627 while (count > 0) { 628 byteoffset = FATOFS(pmp, start); 629 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 630 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 631 if (error) { 632 brelse(bp); 633 return (error); 634 } 635 while (count > 0) { 636 start++; 637 newc = --count > 0 ? start : fillwith; 638 switch (pmp->pm_fatmask) { 639 case FAT12_MASK: 640 readcn = getushort(&bp->b_data[bo]); 641 if (start & 1) { 642 readcn &= 0xf000; 643 readcn |= newc & 0xfff; 644 } else { 645 readcn &= 0x000f; 646 readcn |= newc << 4; 647 } 648 putushort(&bp->b_data[bo], readcn); 649 bo++; 650 if (!(start & 1)) 651 bo++; 652 break; 653 case FAT16_MASK: 654 putushort(&bp->b_data[bo], newc); 655 bo += 2; 656 break; 657 case FAT32_MASK: 658 readcn = getulong(&bp->b_data[bo]); 659 readcn &= ~pmp->pm_fatmask; 660 readcn |= newc & pmp->pm_fatmask; 661 putulong(&bp->b_data[bo], readcn); 662 bo += 4; 663 break; 664 } 665 if (bo >= bsize) 666 break; 667 } 668 updatefats(pmp, bp, bn); 669 } 670 pmp->pm_fmod = 1; 671 return (0); 672 } 673 674 /* 675 * Check the length of a free cluster chain starting at start. 676 * 677 * pmp - mount point 678 * start - start of chain 679 * count - maximum interesting length 680 */ 681 int 682 chainlength(pmp, start, count) 683 struct msdosfsmount *pmp; 684 u_long start; 685 u_long count; 686 { 687 u_long idx, max_idx; 688 u_int map; 689 u_long len; 690 691 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 692 idx = start / N_INUSEBITS; 693 start %= N_INUSEBITS; 694 map = pmp->pm_inusemap[idx]; 695 map &= ~((1 << start) - 1); 696 if (map) { 697 len = ffs(map) - 1 - start; 698 return (len > count ? count : len); 699 } 700 len = N_INUSEBITS - start; 701 if (len >= count) 702 return (count); 703 while (++idx <= max_idx) { 704 if (len >= count) 705 break; 706 if ((map = pmp->pm_inusemap[idx]) != NULL) { 707 len += ffs(map) - 1; 708 break; 709 } 710 len += N_INUSEBITS; 711 } 712 return (len > count ? count : len); 713 } 714 715 /* 716 * Allocate contigous free clusters. 717 * 718 * pmp - mount point. 719 * start - start of cluster chain. 720 * count - number of clusters to allocate. 721 * fillwith - put this value into the fat entry for the 722 * last allocated cluster. 723 * retcluster - put the first allocated cluster's number here. 724 * got - how many clusters were actually allocated. 725 */ 726 int 727 chainalloc(pmp, start, count, fillwith, retcluster, got) 728 struct msdosfsmount *pmp; 729 u_long start; 730 u_long count; 731 u_long fillwith; 732 u_long *retcluster; 733 u_long *got; 734 { 735 int error; 736 u_long cl, n; 737 738 for (cl = start, n = count; n-- > 0;) 739 usemap_alloc(pmp, cl++); 740 if ((error = fatchain(pmp, start, count, fillwith)) != 0) 741 return (error); 742 #ifdef MSDOSFS_DEBUG 743 printf("clusteralloc(): allocated cluster chain at %d (%d clusters)\n", 744 start, count); 745 #endif 746 if (retcluster) 747 *retcluster = start; 748 if (got) 749 *got = count; 750 return (0); 751 } 752 753 /* 754 * Allocate contiguous free clusters. 755 * 756 * pmp - mount point. 757 * start - preferred start of cluster chain. 758 * count - number of clusters requested. 759 * fillwith - put this value into the fat entry for the 760 * last allocated cluster. 761 * retcluster - put the first allocated cluster's number here. 762 * got - how many clusters were actually allocated. 763 */ 764 int 765 clusteralloc(pmp, start, count, fillwith, retcluster, got) 766 struct msdosfsmount *pmp; 767 u_long start; 768 u_long count; 769 u_long fillwith; 770 u_long *retcluster; 771 u_long *got; 772 { 773 u_long idx; 774 u_long len, newst, foundl, cn, l; 775 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 776 u_int map; 777 778 #ifdef MSDOSFS_DEBUG 779 printf("clusteralloc(): find %d clusters\n",count); 780 #endif 781 if (start) { 782 if ((len = chainlength(pmp, start, count)) >= count) 783 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 784 } else { 785 /* 786 * This is a new file, initialize start 787 */ 788 struct timeval tv; 789 790 microtime(&tv); 791 start = (tv.tv_usec >> 10) | tv.tv_usec; 792 len = 0; 793 } 794 795 /* 796 * Start at a (pseudo) random place to maximize cluster runs 797 * under multiple writers. 798 */ 799 newst = (start * 1103515245 + 12345) % (pmp->pm_maxcluster + 1); 800 foundl = 0; 801 802 for (cn = newst; cn <= pmp->pm_maxcluster;) { 803 idx = cn / N_INUSEBITS; 804 map = pmp->pm_inusemap[idx]; 805 map |= (1 << (cn % N_INUSEBITS)) - 1; 806 if (map != (u_int)-1) { 807 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 808 if ((l = chainlength(pmp, cn, count)) >= count) 809 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 810 if (l > foundl) { 811 foundcn = cn; 812 foundl = l; 813 } 814 cn += l + 1; 815 continue; 816 } 817 cn += N_INUSEBITS - cn % N_INUSEBITS; 818 } 819 for (cn = 0; cn < newst;) { 820 idx = cn / N_INUSEBITS; 821 map = pmp->pm_inusemap[idx]; 822 map |= (1 << (cn % N_INUSEBITS)) - 1; 823 if (map != (u_int)-1) { 824 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 825 if ((l = chainlength(pmp, cn, count)) >= count) 826 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 827 if (l > foundl) { 828 foundcn = cn; 829 foundl = l; 830 } 831 cn += l + 1; 832 continue; 833 } 834 cn += N_INUSEBITS - cn % N_INUSEBITS; 835 } 836 837 if (!foundl) 838 return (ENOSPC); 839 840 if (len) 841 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 842 else 843 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 844 } 845 846 847 /* 848 * Free a chain of clusters. 849 * 850 * pmp - address of the msdosfs mount structure for the filesystem 851 * containing the cluster chain to be freed. 852 * startcluster - number of the 1st cluster in the chain of clusters to be 853 * freed. 854 */ 855 int 856 freeclusterchain(pmp, cluster) 857 struct msdosfsmount *pmp; 858 u_long cluster; 859 { 860 int error; 861 struct buf *bp = NULL; 862 u_long bn, bo, bsize, byteoffset; 863 u_long readcn, lbn = -1; 864 865 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 866 byteoffset = FATOFS(pmp, cluster); 867 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 868 if (lbn != bn) { 869 if (bp) 870 updatefats(pmp, bp, lbn); 871 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 872 if (error) { 873 brelse(bp); 874 return (error); 875 } 876 lbn = bn; 877 } 878 usemap_free(pmp, cluster); 879 switch (pmp->pm_fatmask) { 880 case FAT12_MASK: 881 readcn = getushort(&bp->b_data[bo]); 882 if (cluster & 1) { 883 cluster = readcn >> 4; 884 readcn &= 0x000f; 885 readcn |= MSDOSFSFREE << 4; 886 } else { 887 cluster = readcn; 888 readcn &= 0xf000; 889 readcn |= MSDOSFSFREE & 0xfff; 890 } 891 putushort(&bp->b_data[bo], readcn); 892 break; 893 case FAT16_MASK: 894 cluster = getushort(&bp->b_data[bo]); 895 putushort(&bp->b_data[bo], MSDOSFSFREE); 896 break; 897 case FAT32_MASK: 898 cluster = getulong(&bp->b_data[bo]); 899 putulong(&bp->b_data[bo], 900 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 901 break; 902 } 903 cluster &= pmp->pm_fatmask; 904 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 905 cluster |= pmp->pm_fatmask; 906 } 907 if (bp) 908 updatefats(pmp, bp, bn); 909 return (0); 910 } 911 912 /* 913 * Read in fat blocks looking for free clusters. For every free cluster 914 * found turn off its corresponding bit in the pm_inusemap. 915 */ 916 int 917 fillinusemap(pmp) 918 struct msdosfsmount *pmp; 919 { 920 struct buf *bp = NULL; 921 u_long cn, readcn; 922 int error; 923 u_long bn, bo, bsize, byteoffset; 924 925 /* 926 * Mark all clusters in use, we mark the free ones in the fat scan 927 * loop further down. 928 */ 929 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 930 pmp->pm_inusemap[cn] = (u_int)-1; 931 932 /* 933 * Figure how many free clusters are in the filesystem by ripping 934 * through the fat counting the number of entries whose content is 935 * zero. These represent free clusters. 936 */ 937 pmp->pm_freeclustercount = 0; 938 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 939 byteoffset = FATOFS(pmp, cn); 940 bo = byteoffset % pmp->pm_fatblocksize; 941 if (!bo || !bp) { 942 /* Read new FAT block */ 943 if (bp) 944 brelse(bp); 945 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 946 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 947 if (error) { 948 brelse(bp); 949 return (error); 950 } 951 } 952 if (FAT32(pmp)) 953 readcn = getulong(&bp->b_data[bo]); 954 else 955 readcn = getushort(&bp->b_data[bo]); 956 if (FAT12(pmp) && (cn & 1)) 957 readcn >>= 4; 958 readcn &= pmp->pm_fatmask; 959 960 if (readcn == 0) 961 usemap_free(pmp, cn); 962 } 963 brelse(bp); 964 return (0); 965 } 966 967 /* 968 * Allocate a new cluster and chain it onto the end of the file. 969 * 970 * dep - the file to extend 971 * count - number of clusters to allocate 972 * bpp - where to return the address of the buf header for the first new 973 * file block 974 * ncp - where to put cluster number of the first newly allocated cluster 975 * If this pointer is 0, do not return the cluster number. 976 * flags - see fat.h 977 * 978 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 979 * the de_flag field of the denode and it does not change the de_FileSize 980 * field. This is left for the caller to do. 981 */ 982 int 983 extendfile(dep, count, bpp, ncp, flags) 984 struct denode *dep; 985 u_long count; 986 struct buf **bpp; 987 u_long *ncp; 988 int flags; 989 { 990 int error; 991 u_long frcn; 992 u_long cn, got; 993 struct msdosfsmount *pmp = dep->de_pmp; 994 struct buf *bp; 995 996 /* 997 * Don't try to extend the root directory 998 */ 999 if (dep->de_StartCluster == MSDOSFSROOT 1000 && (dep->de_Attributes & ATTR_DIRECTORY)) { 1001 printf("extendfile(): attempt to extend root directory\n"); 1002 return (ENOSPC); 1003 } 1004 1005 /* 1006 * If the "file's last cluster" cache entry is empty, and the file 1007 * is not empty, then fill the cache entry by calling pcbmap(). 1008 */ 1009 fc_fileextends++; 1010 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 1011 dep->de_StartCluster != 0) { 1012 fc_lfcempty++; 1013 error = pcbmap(dep, 0xffff, 0, &cn, 0); 1014 /* we expect it to return E2BIG */ 1015 if (error != E2BIG) 1016 return (error); 1017 } 1018 1019 while (count > 0) { 1020 /* 1021 * Allocate a new cluster chain and cat onto the end of the 1022 * file. * If the file is empty we make de_StartCluster point 1023 * to the new block. Note that de_StartCluster being 0 is 1024 * sufficient to be sure the file is empty since we exclude 1025 * attempts to extend the root directory above, and the root 1026 * dir is the only file with a startcluster of 0 that has 1027 * blocks allocated (sort of). 1028 */ 1029 if (dep->de_StartCluster == 0) 1030 cn = 0; 1031 else 1032 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1033 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1034 if (error) 1035 return (error); 1036 1037 count -= got; 1038 1039 /* 1040 * Give them the filesystem relative cluster number if they want 1041 * it. 1042 */ 1043 if (ncp) { 1044 *ncp = cn; 1045 ncp = NULL; 1046 } 1047 1048 if (dep->de_StartCluster == 0) { 1049 dep->de_StartCluster = cn; 1050 frcn = 0; 1051 } else { 1052 error = fatentry(FAT_SET, pmp, 1053 dep->de_fc[FC_LASTFC].fc_fsrcn, 1054 0, cn); 1055 if (error) { 1056 clusterfree(pmp, cn, NULL); 1057 return (error); 1058 } 1059 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1060 } 1061 1062 /* 1063 * Update the "last cluster of the file" entry in the denode's fat 1064 * cache. 1065 */ 1066 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1067 1068 if (flags & DE_CLEAR) { 1069 while (got-- > 0) { 1070 /* 1071 * Get the buf header for the new block of the file. 1072 */ 1073 if (dep->de_Attributes & ATTR_DIRECTORY) 1074 bp = getblk(pmp->pm_devvp, cntobn(pmp, cn++), 1075 pmp->pm_bpcluster, 0, 0); 1076 else { 1077 bp = getblk(DETOV(dep), de_cn2bn(pmp, frcn++), 1078 pmp->pm_bpcluster, 0, 0); 1079 /* 1080 * Do the bmap now, as in msdosfs_write 1081 */ 1082 if (pcbmap(dep, 1083 de_bn2cn(pmp, bp->b_lblkno), 1084 &bp->b_blkno, 0, 0)) 1085 bp->b_blkno = -1; 1086 if (bp->b_blkno == -1) 1087 panic("extendfile: pcbmap"); 1088 } 1089 clrbuf(bp); 1090 if (bpp) { 1091 *bpp = bp; 1092 bpp = NULL; 1093 } else 1094 bdwrite(bp); 1095 } 1096 } 1097 } 1098 1099 return (0); 1100 } 1101