1 /* $OpenBSD: msdosfs_fat.c,v 1.21 2009/08/13 22:34:29 jasper 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(struct msdosfsmount *, uint32_t, uint32_t *, uint32_t *, 87 uint32_t *); 88 void updatefats(struct msdosfsmount *, struct buf *, uint32_t); 89 static __inline void usemap_free(struct msdosfsmount *, uint32_t); 90 static __inline void usemap_alloc(struct msdosfsmount *, uint32_t); 91 static int fatchain(struct msdosfsmount *, uint32_t, uint32_t, uint32_t); 92 int chainlength(struct msdosfsmount *, uint32_t, uint32_t); 93 int chainalloc(struct msdosfsmount *, uint32_t, uint32_t, uint32_t, uint32_t *, 94 uint32_t *); 95 96 static void 97 fatblock(struct msdosfsmount *pmp, uint32_t ofs, uint32_t *bnp, uint32_t *sizep, 98 uint32_t *bop) 99 { 100 uint32_t bn, size; 101 102 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 103 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) * DEV_BSIZE; 104 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 105 106 if (bnp) 107 *bnp = bn; 108 if (sizep) 109 *sizep = size; 110 if (bop) 111 *bop = ofs % pmp->pm_fatblocksize; 112 } 113 114 /* 115 * Map the logical cluster number of a file into a physical disk sector 116 * that is filesystem relative. 117 * 118 * dep - address of denode representing the file of interest 119 * findcn - file relative cluster whose filesystem relative cluster number 120 * and/or block number are/is to be found 121 * bnp - address of where to place the file system relative block number. 122 * If this pointer is null then don't return this quantity. 123 * cnp - address of where to place the file system relative cluster number. 124 * If this pointer is null then don't return this quantity. 125 * 126 * NOTE: Either bnp or cnp must be non-null. 127 * This function has one side effect. If the requested file relative cluster 128 * is beyond the end of file, then the actual number of clusters in the file 129 * is returned in *cnp. This is useful for determining how long a directory is. 130 * If cnp is null, nothing is returned. 131 */ 132 int 133 pcbmap(struct denode *dep, uint32_t findcn, daddr64_t *bnp, uint32_t *cnp, 134 int *sp) 135 { 136 int error; 137 uint32_t i; 138 uint32_t cn; 139 uint32_t prevcn = 0; /* XXX: prevcn could be used uninitialized */ 140 uint32_t byteoffset; 141 uint32_t bn; 142 uint32_t bo; 143 struct buf *bp = NULL; 144 uint32_t bp_bn = -1; 145 struct msdosfsmount *pmp = dep->de_pmp; 146 uint32_t bsize; 147 148 fc_bmapcalls++; 149 150 /* 151 * If they don't give us someplace to return a value then don't 152 * bother doing anything. 153 */ 154 if (bnp == NULL && cnp == NULL && sp == NULL) 155 return (0); 156 157 cn = dep->de_StartCluster; 158 /* 159 * The "file" that makes up the root directory is contiguous, 160 * permanently allocated, of fixed size, and is not made up of 161 * clusters. If the cluster number is beyond the end of the root 162 * directory, then return the number of clusters in the file. 163 */ 164 if (cn == MSDOSFSROOT) { 165 if (dep->de_Attributes & ATTR_DIRECTORY) { 166 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 167 if (cnp) 168 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 169 return (E2BIG); 170 } 171 if (bnp) 172 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 173 if (cnp) 174 *cnp = MSDOSFSROOT; 175 if (sp) 176 *sp = min(pmp->pm_bpcluster, 177 dep->de_FileSize - de_cn2off(pmp, findcn)); 178 return (0); 179 } else { /* just an empty file */ 180 if (cnp) 181 *cnp = 0; 182 return (E2BIG); 183 } 184 } 185 186 /* 187 * All other files do I/O in cluster sized blocks 188 */ 189 if (sp) 190 *sp = pmp->pm_bpcluster; 191 192 /* 193 * Rummage around in the fat cache, maybe we can avoid tromping 194 * thru every fat entry for the file. And, keep track of how far 195 * off the cache was from where we wanted to be. 196 */ 197 i = 0; 198 fc_lookup(dep, findcn, &i, &cn); 199 if ((bn = findcn - i) >= LMMAX) 200 fc_largedistance++; 201 else 202 fc_lmdistance[bn]++; 203 204 /* 205 * Handle all other files or directories the normal way. 206 */ 207 for (; i < findcn; i++) { 208 /* 209 * Stop with all reserved clusters, not just with EOF. 210 */ 211 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 212 goto hiteof; 213 byteoffset = FATOFS(pmp, cn); 214 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 215 if (bn != bp_bn) { 216 if (bp) 217 brelse(bp); 218 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 219 if (error) { 220 brelse(bp); 221 return (error); 222 } 223 bp_bn = bn; 224 } 225 prevcn = cn; 226 if (bo >= bsize) { 227 if (bp) 228 brelse(bp); 229 return (EIO); 230 } 231 if (FAT32(pmp)) 232 cn = getulong(&bp->b_data[bo]); 233 else 234 cn = getushort(&bp->b_data[bo]); 235 if (FAT12(pmp) && (prevcn & 1)) 236 cn >>= 4; 237 cn &= pmp->pm_fatmask; 238 239 /* 240 * Force the special cluster numbers 241 * to be the same for all cluster sizes 242 * to let the rest of msdosfs handle 243 * all cases the same. 244 */ 245 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 246 cn |= ~pmp->pm_fatmask; 247 } 248 249 if (!MSDOSFSEOF(pmp, cn)) { 250 if (bp) 251 brelse(bp); 252 if (bnp) 253 *bnp = cntobn(pmp, cn); 254 if (cnp) 255 *cnp = cn; 256 fc_setcache(dep, FC_LASTMAP, i, cn); 257 return (0); 258 } 259 260 hiteof:; 261 if (cnp) 262 *cnp = i; 263 if (bp) 264 brelse(bp); 265 /* update last file cluster entry in the fat cache */ 266 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 267 return (E2BIG); 268 } 269 270 /* 271 * Find the closest entry in the fat cache to the cluster we are looking 272 * for. 273 */ 274 void 275 fc_lookup(struct denode *dep, uint32_t findcn, uint32_t *frcnp, uint32_t *fsrcnp) 276 { 277 int i; 278 uint32_t cn; 279 struct fatcache *closest = 0; 280 281 for (i = 0; i < FC_SIZE; i++) { 282 cn = dep->de_fc[i].fc_frcn; 283 if (cn != FCE_EMPTY && cn <= findcn) { 284 if (closest == 0 || cn > closest->fc_frcn) 285 closest = &dep->de_fc[i]; 286 } 287 } 288 if (closest) { 289 *frcnp = closest->fc_frcn; 290 *fsrcnp = closest->fc_fsrcn; 291 } 292 } 293 294 /* 295 * Purge the fat cache in denode dep of all entries relating to file 296 * relative cluster frcn and beyond. 297 */ 298 void 299 fc_purge(struct denode *dep, u_int frcn) 300 { 301 int i; 302 struct fatcache *fcp; 303 304 fcp = dep->de_fc; 305 for (i = 0; i < FC_SIZE; i++, fcp++) { 306 if (fcp->fc_frcn >= frcn) 307 fcp->fc_frcn = FCE_EMPTY; 308 } 309 } 310 311 /* 312 * Update the fat. 313 * If mirroring the fat, update all copies, with the first copy as last. 314 * Else update only the current fat (ignoring the others). 315 * 316 * pmp - msdosfsmount structure for filesystem to update 317 * bp - addr of modified fat block 318 * fatbn - block number relative to begin of filesystem of the modified fat block. 319 */ 320 void 321 updatefats(struct msdosfsmount *pmp, struct buf *bp, uint32_t fatbn) 322 { 323 int i; 324 struct buf *bpn; 325 326 #ifdef MSDOSFS_DEBUG 327 printf("updatefats(pmp %08, buf %x, fatbn %ld)\n", pmp, bp, fatbn); 328 #endif 329 330 /* 331 * If we have an FSInfo block, update it. 332 */ 333 if (pmp->pm_fsinfo) { 334 if (bread(pmp->pm_devvp, pmp->pm_fsinfo, fsi_size(pmp), NOCRED, 335 &bpn) != 0) { 336 /* 337 * Ignore the error, but turn off FSInfo update for the future. 338 */ 339 pmp->pm_fsinfo = 0; 340 brelse(bpn); 341 } else { 342 struct fsinfo *fp = (struct fsinfo *)bpn->b_data; 343 344 putulong(fp->fsinfree, pmp->pm_freeclustercount); 345 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 346 bwrite(bpn); 347 else 348 bdwrite(bpn); 349 } 350 } 351 352 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 353 /* 354 * Now copy the block(s) of the modified fat to the other copies of 355 * the fat and write them out. This is faster than reading in the 356 * other fats and then writing them back out. This could tie up 357 * the fat for quite a while. Preventing others from accessing it. 358 * To prevent us from going after the fat quite so much we use 359 * delayed writes, unless they specfied "synchronous" when the 360 * filesystem was mounted. If synch is asked for then use 361 * bwrite()'s and really slow things down. 362 */ 363 for (i = 1; i < pmp->pm_FATs; i++) { 364 fatbn += pmp->pm_FATsecs; 365 /* getblk() never fails */ 366 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 0, 0); 367 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 368 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 369 bwrite(bpn); 370 else 371 bdwrite(bpn); 372 } 373 } 374 375 /* 376 * Write out the first (or current) fat last. 377 */ 378 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 379 bwrite(bp); 380 else 381 bdwrite(bp); 382 /* 383 * Maybe update fsinfo sector here? 384 */ 385 } 386 387 /* 388 * Updating entries in 12 bit fats is a pain in the butt. 389 * 390 * The following picture shows where nibbles go when moving from a 12 bit 391 * cluster number into the appropriate bytes in the FAT. 392 * 393 * byte m byte m+1 byte m+2 394 * +----+----+ +----+----+ +----+----+ 395 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 396 * +----+----+ +----+----+ +----+----+ 397 * 398 * +----+----+----+ +----+----+----+ 399 * | 3 0 1 | | 4 5 2 | 400 * +----+----+----+ +----+----+----+ 401 * cluster n cluster n+1 402 * 403 * Where n is even. m = n + (n >> 2) 404 * 405 */ 406 static __inline void 407 usemap_alloc(struct msdosfsmount *pmp, uint32_t cn) 408 { 409 410 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 411 pmp->pm_freeclustercount--; 412 } 413 414 static __inline void 415 usemap_free(struct msdosfsmount *pmp, uint32_t cn) 416 { 417 418 pmp->pm_freeclustercount++; 419 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 420 } 421 422 int 423 clusterfree(struct msdosfsmount *pmp, uint32_t cluster, uint32_t *oldcnp) 424 { 425 int error; 426 uint32_t oldcn; 427 428 usemap_free(pmp, cluster); 429 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 430 if (error) { 431 usemap_alloc(pmp, cluster); 432 return (error); 433 } 434 /* 435 * If the cluster was successfully marked free, then update 436 * the count of free clusters, and turn off the "allocated" 437 * bit in the "in use" cluster bit map. 438 */ 439 if (oldcnp) 440 *oldcnp = oldcn; 441 return (0); 442 } 443 444 /* 445 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 446 * 447 * function - whether to get or set a fat entry 448 * pmp - address of the msdosfsmount structure for the filesystem 449 * whose fat is to be manipulated. 450 * cn - which cluster is of interest 451 * oldcontents - address of a word that is to receive the contents of the 452 * cluster'th entry if this is a get function 453 * newcontents - the new value to be written into the cluster'th element of 454 * the fat if this is a set function. 455 * 456 * This function can also be used to free a cluster by setting the fat entry 457 * for a cluster to 0. 458 * 459 * All copies of the fat are updated if this is a set function. NOTE: If 460 * fatentry() marks a cluster as free it does not update the inusemap in 461 * the msdosfsmount structure. This is left to the caller. 462 */ 463 int 464 fatentry(int function, struct msdosfsmount *pmp, uint32_t cn, uint32_t *oldcontents, 465 uint32_t newcontents) 466 { 467 int error; 468 uint32_t readcn; 469 uint32_t bn, bo, bsize, byteoffset; 470 struct buf *bp; 471 472 #ifdef MSDOSFS_DEBUG 473 printf("fatentry(func %d, pmp %08x, clust %d, oldcon %08x, newcon %d)\n", 474 function, pmp, cn, oldcontents, newcontents); 475 #endif 476 477 #ifdef DIAGNOSTIC 478 /* 479 * Be sure they asked us to do something. 480 */ 481 if ((function & (FAT_SET | FAT_GET)) == 0) { 482 printf("fatentry(): function code doesn't specify get or set\n"); 483 return (EINVAL); 484 } 485 486 /* 487 * If they asked us to return a cluster number but didn't tell us 488 * where to put it, give them an error. 489 */ 490 if ((function & FAT_GET) && oldcontents == NULL) { 491 printf("fatentry(): get function with no place to put result\n"); 492 return (EINVAL); 493 } 494 #endif 495 496 /* 497 * Be sure the requested cluster is in the filesystem. 498 */ 499 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 500 return (EINVAL); 501 502 byteoffset = FATOFS(pmp, cn); 503 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 504 if ((error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp)) != 0) { 505 brelse(bp); 506 return (error); 507 } 508 509 if (function & FAT_GET) { 510 if (FAT32(pmp)) 511 readcn = getulong(&bp->b_data[bo]); 512 else 513 readcn = getushort(&bp->b_data[bo]); 514 if (FAT12(pmp) && (cn & 1)) 515 readcn >>= 4; 516 readcn &= pmp->pm_fatmask; 517 /* map reserved fat entries to same values for all fats */ 518 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 519 readcn |= ~pmp->pm_fatmask; 520 *oldcontents = readcn; 521 } 522 if (function & FAT_SET) { 523 switch (pmp->pm_fatmask) { 524 case FAT12_MASK: 525 readcn = getushort(&bp->b_data[bo]); 526 if (cn & 1) { 527 readcn &= 0x000f; 528 readcn |= newcontents << 4; 529 } else { 530 readcn &= 0xf000; 531 readcn |= newcontents & 0xfff; 532 } 533 putushort(&bp->b_data[bo], readcn); 534 break; 535 case FAT16_MASK: 536 putushort(&bp->b_data[bo], newcontents); 537 break; 538 case FAT32_MASK: 539 /* 540 * According to spec we have to retain the 541 * high order bits of the fat entry. 542 */ 543 readcn = getulong(&bp->b_data[bo]); 544 readcn &= ~FAT32_MASK; 545 readcn |= newcontents & FAT32_MASK; 546 putulong(&bp->b_data[bo], readcn); 547 break; 548 } 549 updatefats(pmp, bp, bn); 550 bp = NULL; 551 pmp->pm_fmod = 1; 552 } 553 if (bp) 554 brelse(bp); 555 return (0); 556 } 557 558 /* 559 * Update a contiguous cluster chain 560 * 561 * pmp - mount point 562 * start - first cluster of chain 563 * count - number of clusters in chain 564 * fillwith - what to write into fat entry of last cluster 565 */ 566 static int 567 fatchain(struct msdosfsmount *pmp, uint32_t start, uint32_t count, uint32_t fillwith) 568 { 569 int error; 570 uint32_t bn, bo, bsize, byteoffset, readcn, newc; 571 struct buf *bp; 572 573 #ifdef MSDOSFS_DEBUG 574 printf("fatchain(pmp %08x, start %d, count %d, fillwith %d)\n", 575 pmp, start, count, fillwith); 576 #endif 577 /* 578 * Be sure the clusters are in the filesystem. 579 */ 580 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 581 return (EINVAL); 582 583 while (count > 0) { 584 byteoffset = FATOFS(pmp, start); 585 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 586 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 587 if (error) { 588 brelse(bp); 589 return (error); 590 } 591 while (count > 0) { 592 start++; 593 newc = --count > 0 ? start : fillwith; 594 switch (pmp->pm_fatmask) { 595 case FAT12_MASK: 596 readcn = getushort(&bp->b_data[bo]); 597 if (start & 1) { 598 readcn &= 0xf000; 599 readcn |= newc & 0xfff; 600 } else { 601 readcn &= 0x000f; 602 readcn |= newc << 4; 603 } 604 putushort(&bp->b_data[bo], readcn); 605 bo++; 606 if (!(start & 1)) 607 bo++; 608 break; 609 case FAT16_MASK: 610 putushort(&bp->b_data[bo], newc); 611 bo += 2; 612 break; 613 case FAT32_MASK: 614 readcn = getulong(&bp->b_data[bo]); 615 readcn &= ~pmp->pm_fatmask; 616 readcn |= newc & pmp->pm_fatmask; 617 putulong(&bp->b_data[bo], readcn); 618 bo += 4; 619 break; 620 } 621 if (bo >= bsize) 622 break; 623 } 624 updatefats(pmp, bp, bn); 625 } 626 pmp->pm_fmod = 1; 627 return (0); 628 } 629 630 /* 631 * Check the length of a free cluster chain starting at start. 632 * 633 * pmp - mount point 634 * start - start of chain 635 * count - maximum interesting length 636 */ 637 int 638 chainlength(struct msdosfsmount *pmp, uint32_t start, uint32_t count) 639 { 640 uint32_t idx, max_idx; 641 u_int map; 642 uint32_t len; 643 644 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 645 idx = start / N_INUSEBITS; 646 start %= N_INUSEBITS; 647 map = pmp->pm_inusemap[idx]; 648 map &= ~((1 << start) - 1); 649 if (map) { 650 len = ffs(map) - 1 - start; 651 return (len > count ? count : len); 652 } 653 len = N_INUSEBITS - start; 654 if (len >= count) 655 return (count); 656 while (++idx <= max_idx) { 657 if (len >= count) 658 break; 659 if ((map = pmp->pm_inusemap[idx]) != 0) { 660 len += ffs(map) - 1; 661 break; 662 } 663 len += N_INUSEBITS; 664 } 665 return (len > count ? count : len); 666 } 667 668 /* 669 * Allocate contigous free clusters. 670 * 671 * pmp - mount point. 672 * start - start of cluster chain. 673 * count - number of clusters to allocate. 674 * fillwith - put this value into the fat entry for the 675 * last allocated cluster. 676 * retcluster - put the first allocated cluster's number here. 677 * got - how many clusters were actually allocated. 678 */ 679 int 680 chainalloc(struct msdosfsmount *pmp, uint32_t start, uint32_t count, 681 uint32_t fillwith, uint32_t *retcluster, uint32_t *got) 682 { 683 int error; 684 uint32_t cl, n; 685 686 for (cl = start, n = count; n-- > 0;) 687 usemap_alloc(pmp, cl++); 688 if ((error = fatchain(pmp, start, count, fillwith)) != 0) 689 return (error); 690 #ifdef MSDOSFS_DEBUG 691 printf("clusteralloc(): allocated cluster chain at %d (%d clusters)\n", 692 start, count); 693 #endif 694 if (retcluster) 695 *retcluster = start; 696 if (got) 697 *got = count; 698 return (0); 699 } 700 701 /* 702 * Allocate contiguous free clusters. 703 * 704 * pmp - mount point. 705 * start - preferred start of cluster chain. 706 * count - number of clusters requested. 707 * fillwith - put this value into the fat entry for the 708 * last allocated cluster. 709 * retcluster - put the first allocated cluster's number here. 710 * got - how many clusters were actually allocated. 711 */ 712 int 713 clusteralloc(struct msdosfsmount *pmp, uint32_t start, uint32_t count, 714 uint32_t fillwith, uint32_t *retcluster, uint32_t *got) 715 { 716 uint32_t idx; 717 uint32_t len, newst, foundl, cn, l; 718 uint32_t foundcn = 0; /* XXX: foundcn could be used uninitialized */ 719 u_int map; 720 721 #ifdef MSDOSFS_DEBUG 722 printf("clusteralloc(): find %d clusters\n",count); 723 #endif 724 if (start) { 725 if ((len = chainlength(pmp, start, count)) >= count) 726 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 727 } else { 728 /* 729 * This is a new file, initialize start 730 */ 731 struct timeval tv; 732 733 microtime(&tv); 734 start = (tv.tv_usec >> 10) | tv.tv_usec; 735 len = 0; 736 } 737 738 /* 739 * Start at a (pseudo) random place to maximize cluster runs 740 * under multiple writers. 741 */ 742 newst = (start * 1103515245 + 12345) % (pmp->pm_maxcluster + 1); 743 foundl = 0; 744 745 for (cn = newst; cn <= pmp->pm_maxcluster;) { 746 idx = cn / N_INUSEBITS; 747 map = pmp->pm_inusemap[idx]; 748 map |= (1 << (cn % N_INUSEBITS)) - 1; 749 if (map != (u_int)-1) { 750 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 751 if ((l = chainlength(pmp, cn, count)) >= count) 752 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 753 if (l > foundl) { 754 foundcn = cn; 755 foundl = l; 756 } 757 cn += l + 1; 758 continue; 759 } 760 cn += N_INUSEBITS - cn % N_INUSEBITS; 761 } 762 for (cn = 0; cn < newst;) { 763 idx = cn / N_INUSEBITS; 764 map = pmp->pm_inusemap[idx]; 765 map |= (1 << (cn % N_INUSEBITS)) - 1; 766 if (map != (u_int)-1) { 767 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 768 if ((l = chainlength(pmp, cn, count)) >= count) 769 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 770 if (l > foundl) { 771 foundcn = cn; 772 foundl = l; 773 } 774 cn += l + 1; 775 continue; 776 } 777 cn += N_INUSEBITS - cn % N_INUSEBITS; 778 } 779 780 if (!foundl) 781 return (ENOSPC); 782 783 if (len) 784 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 785 else 786 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 787 } 788 789 790 /* 791 * Free a chain of clusters. 792 * 793 * pmp - address of the msdosfs mount structure for the filesystem 794 * containing the cluster chain to be freed. 795 * startcluster - number of the 1st cluster in the chain of clusters to be 796 * freed. 797 */ 798 int 799 freeclusterchain(struct msdosfsmount *pmp, uint32_t cluster) 800 { 801 int error; 802 struct buf *bp = NULL; 803 uint32_t bn, bo, bsize, byteoffset; 804 uint32_t readcn, lbn = -1; 805 806 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 807 byteoffset = FATOFS(pmp, cluster); 808 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 809 if (lbn != bn) { 810 if (bp) 811 updatefats(pmp, bp, lbn); 812 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 813 if (error) { 814 brelse(bp); 815 return (error); 816 } 817 lbn = bn; 818 } 819 usemap_free(pmp, cluster); 820 switch (pmp->pm_fatmask) { 821 case FAT12_MASK: 822 readcn = getushort(&bp->b_data[bo]); 823 if (cluster & 1) { 824 cluster = readcn >> 4; 825 readcn &= 0x000f; 826 readcn |= MSDOSFSFREE << 4; 827 } else { 828 cluster = readcn; 829 readcn &= 0xf000; 830 readcn |= MSDOSFSFREE & 0xfff; 831 } 832 putushort(&bp->b_data[bo], readcn); 833 break; 834 case FAT16_MASK: 835 cluster = getushort(&bp->b_data[bo]); 836 putushort(&bp->b_data[bo], MSDOSFSFREE); 837 break; 838 case FAT32_MASK: 839 cluster = getulong(&bp->b_data[bo]); 840 putulong(&bp->b_data[bo], 841 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 842 break; 843 } 844 cluster &= pmp->pm_fatmask; 845 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 846 cluster |= pmp->pm_fatmask; 847 } 848 if (bp) 849 updatefats(pmp, bp, bn); 850 return (0); 851 } 852 853 /* 854 * Read in fat blocks looking for free clusters. For every free cluster 855 * found turn off its corresponding bit in the pm_inusemap. 856 */ 857 int 858 fillinusemap(struct msdosfsmount *pmp) 859 { 860 struct buf *bp = NULL; 861 uint32_t cn, readcn; 862 int error; 863 uint32_t bn, bo, bsize, byteoffset; 864 865 /* 866 * Mark all clusters in use, we mark the free ones in the fat scan 867 * loop further down. 868 */ 869 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 870 pmp->pm_inusemap[cn] = (u_int)-1; 871 872 /* 873 * Figure how many free clusters are in the filesystem by ripping 874 * through the fat counting the number of entries whose content is 875 * zero. These represent free clusters. 876 */ 877 pmp->pm_freeclustercount = 0; 878 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 879 byteoffset = FATOFS(pmp, cn); 880 bo = byteoffset % pmp->pm_fatblocksize; 881 if (!bo || !bp) { 882 /* Read new FAT block */ 883 if (bp) 884 brelse(bp); 885 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 886 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 887 if (error) { 888 brelse(bp); 889 return (error); 890 } 891 } 892 if (FAT32(pmp)) 893 readcn = getulong(&bp->b_data[bo]); 894 else 895 readcn = getushort(&bp->b_data[bo]); 896 if (FAT12(pmp) && (cn & 1)) 897 readcn >>= 4; 898 readcn &= pmp->pm_fatmask; 899 900 if (readcn == 0) 901 usemap_free(pmp, cn); 902 } 903 brelse(bp); 904 return (0); 905 } 906 907 /* 908 * Allocate a new cluster and chain it onto the end of the file. 909 * 910 * dep - the file to extend 911 * count - number of clusters to allocate 912 * bpp - where to return the address of the buf header for the first new 913 * file block 914 * ncp - where to put cluster number of the first newly allocated cluster 915 * If this pointer is 0, do not return the cluster number. 916 * flags - see fat.h 917 * 918 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 919 * the de_flag field of the denode and it does not change the de_FileSize 920 * field. This is left for the caller to do. 921 */ 922 int 923 extendfile(struct denode *dep, uint32_t count, struct buf **bpp, uint32_t *ncp, 924 int flags) 925 { 926 int error; 927 uint32_t frcn; 928 uint32_t cn, got; 929 struct msdosfsmount *pmp = dep->de_pmp; 930 struct buf *bp; 931 932 /* 933 * Don't try to extend the root directory 934 */ 935 if (dep->de_StartCluster == MSDOSFSROOT 936 && (dep->de_Attributes & ATTR_DIRECTORY)) { 937 printf("extendfile(): attempt to extend root directory\n"); 938 return (ENOSPC); 939 } 940 941 /* 942 * If the "file's last cluster" cache entry is empty, and the file 943 * is not empty, then fill the cache entry by calling pcbmap(). 944 */ 945 fc_fileextends++; 946 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 947 dep->de_StartCluster != 0) { 948 fc_lfcempty++; 949 error = pcbmap(dep, 0xffff, 0, &cn, 0); 950 /* we expect it to return E2BIG */ 951 if (error != E2BIG) 952 return (error); 953 } 954 955 while (count > 0) { 956 /* 957 * Allocate a new cluster chain and cat onto the end of the 958 * file. * If the file is empty we make de_StartCluster point 959 * to the new block. Note that de_StartCluster being 0 is 960 * sufficient to be sure the file is empty since we exclude 961 * attempts to extend the root directory above, and the root 962 * dir is the only file with a startcluster of 0 that has 963 * blocks allocated (sort of). 964 */ 965 if (dep->de_StartCluster == 0) 966 cn = 0; 967 else 968 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 969 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 970 if (error) 971 return (error); 972 973 count -= got; 974 975 /* 976 * Give them the filesystem relative cluster number if they want 977 * it. 978 */ 979 if (ncp) { 980 *ncp = cn; 981 ncp = NULL; 982 } 983 984 if (dep->de_StartCluster == 0) { 985 dep->de_StartCluster = cn; 986 frcn = 0; 987 } else { 988 error = fatentry(FAT_SET, pmp, 989 dep->de_fc[FC_LASTFC].fc_fsrcn, 990 0, cn); 991 if (error) { 992 clusterfree(pmp, cn, NULL); 993 return (error); 994 } 995 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 996 } 997 998 /* 999 * Update the "last cluster of the file" entry in the denode's fat 1000 * cache. 1001 */ 1002 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1003 1004 if (flags & DE_CLEAR) { 1005 while (got-- > 0) { 1006 /* 1007 * Get the buf header for the new block of the file. 1008 */ 1009 if (dep->de_Attributes & ATTR_DIRECTORY) 1010 bp = getblk(pmp->pm_devvp, cntobn(pmp, cn++), 1011 pmp->pm_bpcluster, 0, 0); 1012 else { 1013 bp = getblk(DETOV(dep), de_cn2bn(pmp, frcn++), 1014 pmp->pm_bpcluster, 0, 0); 1015 /* 1016 * Do the bmap now, as in msdosfs_write 1017 */ 1018 if (pcbmap(dep, 1019 de_bn2cn(pmp, bp->b_lblkno), 1020 &bp->b_blkno, 0, 0)) 1021 bp->b_blkno = -1; 1022 if (bp->b_blkno == -1) 1023 panic("extendfile: pcbmap"); 1024 } 1025 clrbuf(bp); 1026 if (bpp) { 1027 *bpp = bp; 1028 bpp = NULL; 1029 } else 1030 bdwrite(bp); 1031 } 1032 } 1033 } 1034 1035 return (0); 1036 } 1037