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