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sys/fs/msdosfs/msdosfs_fat.c
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1 /* $FreeBSD: releng/9.0/sys/fs/msdosfs/msdosfs_fat.c 204472 2010-02-28 17:15:45Z kib $ */ 2 /* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 ws Exp $ */ 3 4 /*- 5 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank. 6 * Copyright (C) 1994, 1995, 1997 TooLs GmbH. 7 * All rights reserved. 8 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below). 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by TooLs GmbH. 21 * 4. The name of TooLs GmbH may not be used to endorse or promote products 22 * derived from this software without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 29 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 30 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 31 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 32 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 33 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 /*- 36 * Written by Paul Popelka (paulp@uts.amdahl.com) 37 * 38 * You can do anything you want with this software, just don't say you wrote 39 * it, and don't remove this notice. 40 * 41 * This software is provided "as is". 42 * 43 * The author supplies this software to be publicly redistributed on the 44 * understanding that the author is not responsible for the correct 45 * functioning of this software in any circumstances and is not liable for 46 * any damages caused by this software. 47 * 48 * October 1992 49 */ 50 51 #include <sys/param.h> 52 #include <sys/systm.h> 53 #include <sys/buf.h> 54 #include <sys/mount.h> 55 #include <sys/vnode.h> 56 57 #include <fs/msdosfs/bpb.h> 58 #include <fs/msdosfs/direntry.h> 59 #include <fs/msdosfs/denode.h> 60 #include <fs/msdosfs/fat.h> 61 #include <fs/msdosfs/msdosfsmount.h> 62 63 static int chainalloc(struct msdosfsmount *pmp, u_long start, 64 u_long count, u_long fillwith, u_long *retcluster, 65 u_long *got); 66 static int chainlength(struct msdosfsmount *pmp, u_long start, 67 u_long count); 68 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 69 u_long *sizep, u_long *bop); 70 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 71 u_long fillwith); 72 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 73 u_long *fsrcnp); 74 static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 75 u_long fatbn); 76 static __inline void 77 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 78 static __inline void 79 usemap_free(struct msdosfsmount *pmp, u_long cn); 80 static int clusteralloc1(struct msdosfsmount *pmp, u_long start, 81 u_long count, u_long fillwith, u_long *retcluster, 82 u_long *got); 83 84 static void 85 fatblock(pmp, ofs, bnp, sizep, bop) 86 struct msdosfsmount *pmp; 87 u_long ofs; 88 u_long *bnp; 89 u_long *sizep; 90 u_long *bop; 91 { 92 u_long bn, size; 93 94 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 95 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 96 * DEV_BSIZE; 97 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 98 99 if (bnp) 100 *bnp = bn; 101 if (sizep) 102 *sizep = size; 103 if (bop) 104 *bop = ofs % pmp->pm_fatblocksize; 105 } 106 107 /* 108 * Map the logical cluster number of a file into a physical disk sector 109 * that is filesystem relative. 110 * 111 * dep - address of denode representing the file of interest 112 * findcn - file relative cluster whose filesystem relative cluster number 113 * and/or block number are/is to be found 114 * bnp - address of where to place the filesystem relative block number. 115 * If this pointer is null then don't return this quantity. 116 * cnp - address of where to place the filesystem relative cluster number. 117 * If this pointer is null then don't return this quantity. 118 * 119 * NOTE: Either bnp or cnp must be non-null. 120 * This function has one side effect. If the requested file relative cluster 121 * is beyond the end of file, then the actual number of clusters in the file 122 * is returned in *cnp. This is useful for determining how long a directory is. 123 * If cnp is null, nothing is returned. 124 */ 125 int 126 pcbmap(dep, findcn, bnp, cnp, sp) 127 struct denode *dep; 128 u_long findcn; /* file relative cluster to get */ 129 daddr_t *bnp; /* returned filesys relative blk number */ 130 u_long *cnp; /* returned cluster number */ 131 int *sp; /* returned block size */ 132 { 133 int error; 134 u_long i; 135 u_long cn; 136 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 137 u_long byteoffset; 138 u_long bn; 139 u_long bo; 140 struct buf *bp = NULL; 141 u_long bp_bn = -1; 142 struct msdosfsmount *pmp = dep->de_pmp; 143 u_long bsize; 144 145 KASSERT(bnp != NULL || cnp != NULL || sp != NULL, 146 ("pcbmap: extra call")); 147 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap"); 148 149 cn = dep->de_StartCluster; 150 /* 151 * The "file" that makes up the root directory is contiguous, 152 * permanently allocated, of fixed size, and is not made up of 153 * clusters. If the cluster number is beyond the end of the root 154 * directory, then return the number of clusters in the file. 155 */ 156 if (cn == MSDOSFSROOT) { 157 if (dep->de_Attributes & ATTR_DIRECTORY) { 158 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 159 if (cnp) 160 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 161 return (E2BIG); 162 } 163 if (bnp) 164 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 165 if (cnp) 166 *cnp = MSDOSFSROOT; 167 if (sp) 168 *sp = min(pmp->pm_bpcluster, 169 dep->de_FileSize - de_cn2off(pmp, findcn)); 170 return (0); 171 } else { /* just an empty file */ 172 if (cnp) 173 *cnp = 0; 174 return (E2BIG); 175 } 176 } 177 178 /* 179 * All other files do I/O in cluster sized blocks 180 */ 181 if (sp) 182 *sp = pmp->pm_bpcluster; 183 184 /* 185 * Rummage around in the fat cache, maybe we can avoid tromping 186 * thru every fat entry for the file. And, keep track of how far 187 * off the cache was from where we wanted to be. 188 */ 189 i = 0; 190 fc_lookup(dep, findcn, &i, &cn); 191 192 /* 193 * Handle all other files or directories the normal way. 194 */ 195 for (; i < findcn; i++) { 196 /* 197 * Stop with all reserved clusters, not just with EOF. 198 */ 199 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 200 goto hiteof; 201 byteoffset = FATOFS(pmp, cn); 202 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 203 if (bn != bp_bn) { 204 if (bp) 205 brelse(bp); 206 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 207 if (error) { 208 brelse(bp); 209 return (error); 210 } 211 bp_bn = bn; 212 } 213 prevcn = cn; 214 if (bo >= bsize) { 215 if (bp) 216 brelse(bp); 217 return (EIO); 218 } 219 if (FAT32(pmp)) 220 cn = getulong(&bp->b_data[bo]); 221 else 222 cn = getushort(&bp->b_data[bo]); 223 if (FAT12(pmp) && (prevcn & 1)) 224 cn >>= 4; 225 cn &= pmp->pm_fatmask; 226 227 /* 228 * Force the special cluster numbers 229 * to be the same for all cluster sizes 230 * to let the rest of msdosfs handle 231 * all cases the same. 232 */ 233 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 234 cn |= ~pmp->pm_fatmask; 235 } 236 237 if (!MSDOSFSEOF(pmp, cn)) { 238 if (bp) 239 brelse(bp); 240 if (bnp) 241 *bnp = cntobn(pmp, cn); 242 if (cnp) 243 *cnp = cn; 244 fc_setcache(dep, FC_LASTMAP, i, cn); 245 return (0); 246 } 247 248 hiteof:; 249 if (cnp) 250 *cnp = i; 251 if (bp) 252 brelse(bp); 253 /* update last file cluster entry in the fat cache */ 254 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 255 return (E2BIG); 256 } 257 258 /* 259 * Find the closest entry in the fat cache to the cluster we are looking 260 * for. 261 */ 262 static void 263 fc_lookup(dep, findcn, frcnp, fsrcnp) 264 struct denode *dep; 265 u_long findcn; 266 u_long *frcnp; 267 u_long *fsrcnp; 268 { 269 int i; 270 u_long cn; 271 struct fatcache *closest = 0; 272 273 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup"); 274 275 for (i = 0; i < FC_SIZE; i++) { 276 cn = dep->de_fc[i].fc_frcn; 277 if (cn != FCE_EMPTY && cn <= findcn) { 278 if (closest == 0 || cn > closest->fc_frcn) 279 closest = &dep->de_fc[i]; 280 } 281 } 282 if (closest) { 283 *frcnp = closest->fc_frcn; 284 *fsrcnp = closest->fc_fsrcn; 285 } 286 } 287 288 /* 289 * Purge the fat cache in denode dep of all entries relating to file 290 * relative cluster frcn and beyond. 291 */ 292 void 293 fc_purge(dep, frcn) 294 struct denode *dep; 295 u_int frcn; 296 { 297 int i; 298 struct fatcache *fcp; 299 300 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge"); 301 302 fcp = dep->de_fc; 303 for (i = 0; i < FC_SIZE; i++, fcp++) { 304 if (fcp->fc_frcn >= frcn) 305 fcp->fc_frcn = FCE_EMPTY; 306 } 307 } 308 309 /* 310 * Update the fat. 311 * If mirroring the fat, update all copies, with the first copy as last. 312 * Else update only the current fat (ignoring the others). 313 * 314 * pmp - msdosfsmount structure for filesystem to update 315 * bp - addr of modified fat block 316 * fatbn - block number relative to begin of filesystem of the modified fat block. 317 */ 318 static void 319 updatefats(pmp, bp, fatbn) 320 struct msdosfsmount *pmp; 321 struct buf *bp; 322 u_long fatbn; 323 { 324 int i; 325 struct buf *bpn; 326 327 #ifdef MSDOSFS_DEBUG 328 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 329 #endif 330 331 /* 332 * If we have an FSInfo block, update it. 333 */ 334 if (pmp->pm_fsinfo) { 335 if (bread(pmp->pm_devvp, pmp->pm_fsinfo, pmp->pm_BytesPerSec, 336 NOCRED, &bpn) != 0) { 337 /* 338 * Ignore the error, but turn off FSInfo update for the future. 339 */ 340 pmp->pm_fsinfo = 0; 341 brelse(bpn); 342 } else { 343 struct fsinfo *fp = (struct fsinfo *)bpn->b_data; 344 345 putulong(fp->fsinfree, pmp->pm_freeclustercount); 346 putulong(fp->fsinxtfree, pmp->pm_nxtfree); 347 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 348 bwrite(bpn); 349 else 350 bdwrite(bpn); 351 } 352 } 353 354 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 355 /* 356 * Now copy the block(s) of the modified fat to the other copies of 357 * the fat and write them out. This is faster than reading in the 358 * other fats and then writing them back out. This could tie up 359 * the fat for quite a while. Preventing others from accessing it. 360 * To prevent us from going after the fat quite so much we use 361 * delayed writes, unless they specfied "synchronous" when the 362 * filesystem was mounted. If synch is asked for then use 363 * bwrite()'s and really slow things down. 364 */ 365 for (i = 1; i < pmp->pm_FATs; i++) { 366 fatbn += pmp->pm_FATsecs; 367 /* getblk() never fails */ 368 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 369 0, 0, 0); 370 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 371 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 372 bwrite(bpn); 373 else 374 bdwrite(bpn); 375 } 376 } 377 378 /* 379 * Write out the first (or current) fat last. 380 */ 381 if (pmp->pm_flags & MSDOSFSMNT_WAITONFAT) 382 bwrite(bp); 383 else 384 bdwrite(bp); 385 /* 386 * Maybe update fsinfo sector here? 387 */ 388 } 389 390 /* 391 * Updating entries in 12 bit fats is a pain in the butt. 392 * 393 * The following picture shows where nibbles go when moving from a 12 bit 394 * cluster number into the appropriate bytes in the FAT. 395 * 396 * byte m byte m+1 byte m+2 397 * +----+----+ +----+----+ +----+----+ 398 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 399 * +----+----+ +----+----+ +----+----+ 400 * 401 * +----+----+----+ +----+----+----+ 402 * | 3 0 1 | | 4 5 2 | 403 * +----+----+----+ +----+----+----+ 404 * cluster n cluster n+1 405 * 406 * Where n is even. m = n + (n >> 2) 407 * 408 */ 409 static __inline void 410 usemap_alloc(pmp, cn) 411 struct msdosfsmount *pmp; 412 u_long cn; 413 { 414 415 MSDOSFS_ASSERT_MP_LOCKED(pmp); 416 417 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 418 == 0, ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS, 419 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 420 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 421 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little")); 422 pmp->pm_freeclustercount--; 423 } 424 425 static __inline void 426 usemap_free(pmp, cn) 427 struct msdosfsmount *pmp; 428 u_long cn; 429 { 430 431 MSDOSFS_ASSERT_MP_LOCKED(pmp); 432 pmp->pm_freeclustercount++; 433 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 434 != 0, ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS, 435 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 436 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 437 } 438 439 int 440 clusterfree(pmp, cluster, oldcnp) 441 struct msdosfsmount *pmp; 442 u_long cluster; 443 u_long *oldcnp; 444 { 445 int error; 446 u_long oldcn; 447 448 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 449 if (error) 450 return (error); 451 /* 452 * If the cluster was successfully marked free, then update 453 * the count of free clusters, and turn off the "allocated" 454 * bit in the "in use" cluster bit map. 455 */ 456 MSDOSFS_LOCK_MP(pmp); 457 usemap_free(pmp, cluster); 458 MSDOSFS_UNLOCK_MP(pmp); 459 if (oldcnp) 460 *oldcnp = oldcn; 461 return (0); 462 } 463 464 /* 465 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 466 * 467 * function - whether to get or set a fat entry 468 * pmp - address of the msdosfsmount structure for the filesystem 469 * whose fat is to be manipulated. 470 * cn - which cluster is of interest 471 * oldcontents - address of a word that is to receive the contents of the 472 * cluster'th entry if this is a get function 473 * newcontents - the new value to be written into the cluster'th element of 474 * the fat if this is a set function. 475 * 476 * This function can also be used to free a cluster by setting the fat entry 477 * for a cluster to 0. 478 * 479 * All copies of the fat are updated if this is a set function. NOTE: If 480 * fatentry() marks a cluster as free it does not update the inusemap in 481 * the msdosfsmount structure. This is left to the caller. 482 */ 483 int 484 fatentry(function, pmp, cn, oldcontents, newcontents) 485 int function; 486 struct msdosfsmount *pmp; 487 u_long cn; 488 u_long *oldcontents; 489 u_long newcontents; 490 { 491 int error; 492 u_long readcn; 493 u_long bn, bo, bsize, byteoffset; 494 struct buf *bp; 495 496 #ifdef MSDOSFS_DEBUG 497 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 498 function, pmp, cn, oldcontents, newcontents); 499 #endif 500 501 #ifdef DIAGNOSTIC 502 /* 503 * Be sure they asked us to do something. 504 */ 505 if ((function & (FAT_SET | FAT_GET)) == 0) { 506 printf("fatentry(): function code doesn't specify get or set\n"); 507 return (EINVAL); 508 } 509 510 /* 511 * If they asked us to return a cluster number but didn't tell us 512 * where to put it, give them an error. 513 */ 514 if ((function & FAT_GET) && oldcontents == NULL) { 515 printf("fatentry(): get function with no place to put result\n"); 516 return (EINVAL); 517 } 518 #endif 519 520 /* 521 * Be sure the requested cluster is in the filesystem. 522 */ 523 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 524 return (EINVAL); 525 526 byteoffset = FATOFS(pmp, cn); 527 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 528 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 529 if (error) { 530 brelse(bp); 531 return (error); 532 } 533 534 if (function & FAT_GET) { 535 if (FAT32(pmp)) 536 readcn = getulong(&bp->b_data[bo]); 537 else 538 readcn = getushort(&bp->b_data[bo]); 539 if (FAT12(pmp) & (cn & 1)) 540 readcn >>= 4; 541 readcn &= pmp->pm_fatmask; 542 /* map reserved fat entries to same values for all fats */ 543 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 544 readcn |= ~pmp->pm_fatmask; 545 *oldcontents = readcn; 546 } 547 if (function & FAT_SET) { 548 switch (pmp->pm_fatmask) { 549 case FAT12_MASK: 550 readcn = getushort(&bp->b_data[bo]); 551 if (cn & 1) { 552 readcn &= 0x000f; 553 readcn |= newcontents << 4; 554 } else { 555 readcn &= 0xf000; 556 readcn |= newcontents & 0xfff; 557 } 558 putushort(&bp->b_data[bo], readcn); 559 break; 560 case FAT16_MASK: 561 putushort(&bp->b_data[bo], newcontents); 562 break; 563 case FAT32_MASK: 564 /* 565 * According to spec we have to retain the 566 * high order bits of the fat entry. 567 */ 568 readcn = getulong(&bp->b_data[bo]); 569 readcn &= ~FAT32_MASK; 570 readcn |= newcontents & FAT32_MASK; 571 putulong(&bp->b_data[bo], readcn); 572 break; 573 } 574 updatefats(pmp, bp, bn); 575 bp = NULL; 576 pmp->pm_fmod = 1; 577 } 578 if (bp) 579 brelse(bp); 580 return (0); 581 } 582 583 /* 584 * Update a contiguous cluster chain 585 * 586 * pmp - mount point 587 * start - first cluster of chain 588 * count - number of clusters in chain 589 * fillwith - what to write into fat entry of last cluster 590 */ 591 static int 592 fatchain(pmp, start, count, fillwith) 593 struct msdosfsmount *pmp; 594 u_long start; 595 u_long count; 596 u_long fillwith; 597 { 598 int error; 599 u_long bn, bo, bsize, byteoffset, readcn, newc; 600 struct buf *bp; 601 602 #ifdef MSDOSFS_DEBUG 603 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 604 pmp, start, count, fillwith); 605 #endif 606 /* 607 * Be sure the clusters are in the filesystem. 608 */ 609 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 610 return (EINVAL); 611 612 while (count > 0) { 613 byteoffset = FATOFS(pmp, start); 614 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 615 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 616 if (error) { 617 brelse(bp); 618 return (error); 619 } 620 while (count > 0) { 621 start++; 622 newc = --count > 0 ? start : fillwith; 623 switch (pmp->pm_fatmask) { 624 case FAT12_MASK: 625 readcn = getushort(&bp->b_data[bo]); 626 if (start & 1) { 627 readcn &= 0xf000; 628 readcn |= newc & 0xfff; 629 } else { 630 readcn &= 0x000f; 631 readcn |= newc << 4; 632 } 633 putushort(&bp->b_data[bo], readcn); 634 bo++; 635 if (!(start & 1)) 636 bo++; 637 break; 638 case FAT16_MASK: 639 putushort(&bp->b_data[bo], newc); 640 bo += 2; 641 break; 642 case FAT32_MASK: 643 readcn = getulong(&bp->b_data[bo]); 644 readcn &= ~pmp->pm_fatmask; 645 readcn |= newc & pmp->pm_fatmask; 646 putulong(&bp->b_data[bo], readcn); 647 bo += 4; 648 break; 649 } 650 if (bo >= bsize) 651 break; 652 } 653 updatefats(pmp, bp, bn); 654 } 655 pmp->pm_fmod = 1; 656 return (0); 657 } 658 659 /* 660 * Check the length of a free cluster chain starting at start. 661 * 662 * pmp - mount point 663 * start - start of chain 664 * count - maximum interesting length 665 */ 666 static int 667 chainlength(pmp, start, count) 668 struct msdosfsmount *pmp; 669 u_long start; 670 u_long count; 671 { 672 u_long idx, max_idx; 673 u_int map; 674 u_long len; 675 676 MSDOSFS_ASSERT_MP_LOCKED(pmp); 677 678 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 679 idx = start / N_INUSEBITS; 680 start %= N_INUSEBITS; 681 map = pmp->pm_inusemap[idx]; 682 map &= ~((1 << start) - 1); 683 if (map) { 684 len = ffs(map) - 1 - start; 685 return (len > count ? count : len); 686 } 687 len = N_INUSEBITS - start; 688 if (len >= count) 689 return (count); 690 while (++idx <= max_idx) { 691 if (len >= count) 692 break; 693 map = pmp->pm_inusemap[idx]; 694 if (map) { 695 len += ffs(map) - 1; 696 break; 697 } 698 len += N_INUSEBITS; 699 } 700 return (len > count ? count : len); 701 } 702 703 /* 704 * Allocate contigous free clusters. 705 * 706 * pmp - mount point. 707 * start - start of cluster chain. 708 * count - number of clusters to allocate. 709 * fillwith - put this value into the fat entry for the 710 * last allocated cluster. 711 * retcluster - put the first allocated cluster's number here. 712 * got - how many clusters were actually allocated. 713 */ 714 static int 715 chainalloc(pmp, start, count, fillwith, retcluster, got) 716 struct msdosfsmount *pmp; 717 u_long start; 718 u_long count; 719 u_long fillwith; 720 u_long *retcluster; 721 u_long *got; 722 { 723 int error; 724 u_long cl, n; 725 726 MSDOSFS_ASSERT_MP_LOCKED(pmp); 727 728 for (cl = start, n = count; n-- > 0;) 729 usemap_alloc(pmp, cl++); 730 731 error = fatchain(pmp, start, count, fillwith); 732 if (error != 0) 733 return (error); 734 #ifdef MSDOSFS_DEBUG 735 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 736 start, count); 737 #endif 738 if (retcluster) 739 *retcluster = start; 740 if (got) 741 *got = count; 742 pmp->pm_nxtfree = start + count; 743 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 744 pmp->pm_nxtfree = CLUST_FIRST; 745 return (0); 746 } 747 748 /* 749 * Allocate contiguous free clusters. 750 * 751 * pmp - mount point. 752 * start - preferred start of cluster chain. 753 * count - number of clusters requested. 754 * fillwith - put this value into the fat entry for the 755 * last allocated cluster. 756 * retcluster - put the first allocated cluster's number here. 757 * got - how many clusters were actually allocated. 758 */ 759 int 760 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 761 u_long fillwith, u_long *retcluster, u_long *got) 762 { 763 int error; 764 765 MSDOSFS_LOCK_MP(pmp); 766 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 767 MSDOSFS_UNLOCK_MP(pmp); 768 return (error); 769 } 770 771 static int 772 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 773 u_long fillwith, u_long *retcluster, u_long *got) 774 { 775 u_long idx; 776 u_long len, newst, foundl, cn, l; 777 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 778 u_int map; 779 780 MSDOSFS_ASSERT_MP_LOCKED(pmp); 781 782 #ifdef MSDOSFS_DEBUG 783 printf("clusteralloc(): find %lu clusters\n", count); 784 #endif 785 if (start) { 786 if ((len = chainlength(pmp, start, count)) >= count) 787 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 788 } else 789 len = 0; 790 791 newst = pmp->pm_nxtfree; 792 foundl = 0; 793 794 for (cn = newst; cn <= pmp->pm_maxcluster;) { 795 idx = cn / N_INUSEBITS; 796 map = pmp->pm_inusemap[idx]; 797 map |= (1 << (cn % N_INUSEBITS)) - 1; 798 if (map != (u_int)-1) { 799 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 800 if ((l = chainlength(pmp, cn, count)) >= count) 801 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 802 if (l > foundl) { 803 foundcn = cn; 804 foundl = l; 805 } 806 cn += l + 1; 807 continue; 808 } 809 cn += N_INUSEBITS - cn % N_INUSEBITS; 810 } 811 for (cn = 0; cn < newst;) { 812 idx = cn / N_INUSEBITS; 813 map = pmp->pm_inusemap[idx]; 814 map |= (1 << (cn % N_INUSEBITS)) - 1; 815 if (map != (u_int)-1) { 816 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 817 if ((l = chainlength(pmp, cn, count)) >= count) 818 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 819 if (l > foundl) { 820 foundcn = cn; 821 foundl = l; 822 } 823 cn += l + 1; 824 continue; 825 } 826 cn += N_INUSEBITS - cn % N_INUSEBITS; 827 } 828 829 if (!foundl) 830 return (ENOSPC); 831 832 if (len) 833 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 834 else 835 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 836 } 837 838 839 /* 840 * Free a chain of clusters. 841 * 842 * pmp - address of the msdosfs mount structure for the filesystem 843 * containing the cluster chain to be freed. 844 * startcluster - number of the 1st cluster in the chain of clusters to be 845 * freed. 846 */ 847 int 848 freeclusterchain(pmp, cluster) 849 struct msdosfsmount *pmp; 850 u_long cluster; 851 { 852 int error; 853 struct buf *bp = NULL; 854 u_long bn, bo, bsize, byteoffset; 855 u_long readcn, lbn = -1; 856 857 MSDOSFS_LOCK_MP(pmp); 858 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 859 byteoffset = FATOFS(pmp, cluster); 860 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 861 if (lbn != bn) { 862 if (bp) 863 updatefats(pmp, bp, lbn); 864 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 865 if (error) { 866 brelse(bp); 867 MSDOSFS_UNLOCK_MP(pmp); 868 return (error); 869 } 870 lbn = bn; 871 } 872 usemap_free(pmp, cluster); 873 switch (pmp->pm_fatmask) { 874 case FAT12_MASK: 875 readcn = getushort(&bp->b_data[bo]); 876 if (cluster & 1) { 877 cluster = readcn >> 4; 878 readcn &= 0x000f; 879 readcn |= MSDOSFSFREE << 4; 880 } else { 881 cluster = readcn; 882 readcn &= 0xf000; 883 readcn |= MSDOSFSFREE & 0xfff; 884 } 885 putushort(&bp->b_data[bo], readcn); 886 break; 887 case FAT16_MASK: 888 cluster = getushort(&bp->b_data[bo]); 889 putushort(&bp->b_data[bo], MSDOSFSFREE); 890 break; 891 case FAT32_MASK: 892 cluster = getulong(&bp->b_data[bo]); 893 putulong(&bp->b_data[bo], 894 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 895 break; 896 } 897 cluster &= pmp->pm_fatmask; 898 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 899 cluster |= pmp->pm_fatmask; 900 } 901 if (bp) 902 updatefats(pmp, bp, bn); 903 MSDOSFS_UNLOCK_MP(pmp); 904 return (0); 905 } 906 907 /* 908 * Read in fat blocks looking for free clusters. For every free cluster 909 * found turn off its corresponding bit in the pm_inusemap. 910 */ 911 int 912 fillinusemap(pmp) 913 struct msdosfsmount *pmp; 914 { 915 struct buf *bp = NULL; 916 u_long cn, readcn; 917 int error; 918 u_long bn, bo, bsize, byteoffset; 919 920 MSDOSFS_ASSERT_MP_LOCKED(pmp); 921 922 /* 923 * Mark all clusters in use, we mark the free ones in the fat scan 924 * loop further down. 925 */ 926 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 927 pmp->pm_inusemap[cn] = (u_int)-1; 928 929 /* 930 * Figure how many free clusters are in the filesystem by ripping 931 * through the fat counting the number of entries whose content is 932 * zero. These represent free clusters. 933 */ 934 pmp->pm_freeclustercount = 0; 935 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 936 byteoffset = FATOFS(pmp, cn); 937 bo = byteoffset % pmp->pm_fatblocksize; 938 if (!bo || !bp) { 939 /* Read new FAT block */ 940 if (bp) 941 brelse(bp); 942 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 943 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 944 if (error) { 945 brelse(bp); 946 return (error); 947 } 948 } 949 if (FAT32(pmp)) 950 readcn = getulong(&bp->b_data[bo]); 951 else 952 readcn = getushort(&bp->b_data[bo]); 953 if (FAT12(pmp) && (cn & 1)) 954 readcn >>= 4; 955 readcn &= pmp->pm_fatmask; 956 957 if (readcn == 0) 958 usemap_free(pmp, cn); 959 } 960 if (bp != NULL) 961 brelse(bp); 962 return (0); 963 } 964 965 /* 966 * Allocate a new cluster and chain it onto the end of the file. 967 * 968 * dep - the file to extend 969 * count - number of clusters to allocate 970 * bpp - where to return the address of the buf header for the first new 971 * file block 972 * ncp - where to put cluster number of the first newly allocated cluster 973 * If this pointer is 0, do not return the cluster number. 974 * flags - see fat.h 975 * 976 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 977 * the de_flag field of the denode and it does not change the de_FileSize 978 * field. This is left for the caller to do. 979 */ 980 int 981 extendfile(dep, count, bpp, ncp, flags) 982 struct denode *dep; 983 u_long count; 984 struct buf **bpp; 985 u_long *ncp; 986 int flags; 987 { 988 int error; 989 u_long frcn; 990 u_long cn, got; 991 struct msdosfsmount *pmp = dep->de_pmp; 992 struct buf *bp; 993 daddr_t blkno; 994 995 /* 996 * Don't try to extend the root directory 997 */ 998 if (dep->de_StartCluster == MSDOSFSROOT 999 && (dep->de_Attributes & ATTR_DIRECTORY)) { 1000 printf("extendfile(): attempt to extend root directory\n"); 1001 return (ENOSPC); 1002 } 1003 1004 /* 1005 * If the "file's last cluster" cache entry is empty, and the file 1006 * is not empty, then fill the cache entry by calling pcbmap(). 1007 */ 1008 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 1009 dep->de_StartCluster != 0) { 1010 error = pcbmap(dep, 0xffff, 0, &cn, 0); 1011 /* we expect it to return E2BIG */ 1012 if (error != E2BIG) 1013 return (error); 1014 } 1015 1016 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 1017 dep->de_fc[FC_LASTFC].fc_frcn; 1018 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 1019 dep->de_fc[FC_LASTFC].fc_fsrcn; 1020 while (count > 0) { 1021 /* 1022 * Allocate a new cluster chain and cat onto the end of the 1023 * file. * If the file is empty we make de_StartCluster point 1024 * to the new block. Note that de_StartCluster being 0 is 1025 * sufficient to be sure the file is empty since we exclude 1026 * attempts to extend the root directory above, and the root 1027 * dir is the only file with a startcluster of 0 that has 1028 * blocks allocated (sort of). 1029 */ 1030 if (dep->de_StartCluster == 0) 1031 cn = 0; 1032 else 1033 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1034 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1035 if (error) 1036 return (error); 1037 1038 count -= got; 1039 1040 /* 1041 * Give them the filesystem relative cluster number if they want 1042 * it. 1043 */ 1044 if (ncp) { 1045 *ncp = cn; 1046 ncp = NULL; 1047 } 1048 1049 if (dep->de_StartCluster == 0) { 1050 dep->de_StartCluster = cn; 1051 frcn = 0; 1052 } else { 1053 error = fatentry(FAT_SET, pmp, 1054 dep->de_fc[FC_LASTFC].fc_fsrcn, 1055 0, cn); 1056 if (error) { 1057 clusterfree(pmp, cn, NULL); 1058 return (error); 1059 } 1060 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1061 } 1062 1063 /* 1064 * Update the "last cluster of the file" entry in the denode's fat 1065 * cache. 1066 */ 1067 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1068 1069 if (flags & DE_CLEAR) { 1070 while (got-- > 0) { 1071 /* 1072 * Get the buf header for the new block of the file. 1073 */ 1074 if (dep->de_Attributes & ATTR_DIRECTORY) 1075 bp = getblk(pmp->pm_devvp, 1076 cntobn(pmp, cn++), 1077 pmp->pm_bpcluster, 0, 0, 0); 1078 else { 1079 bp = getblk(DETOV(dep), 1080 frcn++, 1081 pmp->pm_bpcluster, 0, 0, 0); 1082 /* 1083 * Do the bmap now, as in msdosfs_write 1084 */ 1085 if (pcbmap(dep, 1086 bp->b_lblkno, 1087 &blkno, 0, 0)) 1088 bp->b_blkno = -1; 1089 if (bp->b_blkno == -1) 1090 panic("extendfile: pcbmap"); 1091 else 1092 bp->b_blkno = blkno; 1093 } 1094 vfs_bio_clrbuf(bp); 1095 if (bpp) { 1096 *bpp = bp; 1097 bpp = NULL; 1098 } else 1099 bdwrite(bp); 1100 } 1101 } 1102 } 1103 1104 return (0); 1105 } 1106 1107 /*- 1108 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1109 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1110 * this bit is not defined for FAT12 volumes, which are always assumed to 1111 * be dirty. 1112 * 1113 * The fatentry() routine only works on cluster numbers that a file could 1114 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1115 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1116 * 1117 * Inputs: 1118 * pmp The MS-DOS volume to mark 1119 * dirty Non-zero if the volume should be marked dirty; zero if it 1120 * should be marked clean 1121 * 1122 * Result: 1123 * 0 Success 1124 * EROFS Volume is read-only 1125 * ? (other errors from called routines) 1126 */ 1127 int 1128 markvoldirty(struct msdosfsmount *pmp, int dirty) 1129 { 1130 struct buf *bp; 1131 u_long bn, bo, bsize, byteoffset, fatval; 1132 int error; 1133 1134 /* 1135 * FAT12 does not support a "clean" bit, so don't do anything for 1136 * FAT12. 1137 */ 1138 if (FAT12(pmp)) 1139 return (0); 1140 1141 /* Can't change the bit on a read-only filesystem. */ 1142 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1143 return (EROFS); 1144 1145 /* 1146 * Fetch the block containing the FAT entry. It is given by the 1147 * pseudo-cluster 1. 1148 */ 1149 byteoffset = FATOFS(pmp, 1); 1150 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1151 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1152 if (error) { 1153 brelse(bp); 1154 return (error); 1155 } 1156 1157 /* 1158 * Get the current value of the FAT entry and set/clear the relevant 1159 * bit. Dirty means clear the "clean" bit; clean means set the 1160 * "clean" bit. 1161 */ 1162 if (FAT32(pmp)) { 1163 /* FAT32 uses bit 27. */ 1164 fatval = getulong(&bp->b_data[bo]); 1165 if (dirty) 1166 fatval &= 0xF7FFFFFF; 1167 else 1168 fatval |= 0x08000000; 1169 putulong(&bp->b_data[bo], fatval); 1170 } else { 1171 /* Must be FAT16; use bit 15. */ 1172 fatval = getushort(&bp->b_data[bo]); 1173 if (dirty) 1174 fatval &= 0x7FFF; 1175 else 1176 fatval |= 0x8000; 1177 putushort(&bp->b_data[bo], fatval); 1178 } 1179 1180 /* Write out the modified FAT block synchronously. */ 1181 return (bwrite(bp)); 1182 }
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