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 #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(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep, 86 u_long *bop) 87 { 88 u_long bn, size; 89 90 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 91 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 92 * DEV_BSIZE; 93 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 94 95 if (bnp) 96 *bnp = bn; 97 if (sizep) 98 *sizep = size; 99 if (bop) 100 *bop = ofs % pmp->pm_fatblocksize; 101 } 102 103 /* 104 * Map the logical cluster number of a file into a physical disk sector 105 * that is filesystem relative. 106 * 107 * dep - address of denode representing the file of interest 108 * findcn - file relative cluster whose filesystem relative cluster number 109 * and/or block number are/is to be found 110 * bnp - address of where to place the filesystem relative block number. 111 * If this pointer is null then don't return this quantity. 112 * cnp - address of where to place the filesystem relative cluster number. 113 * If this pointer is null then don't return this quantity. 114 * sp - pointer to returned block size 115 * 116 * NOTE: Either bnp or cnp must be non-null. 117 * This function has one side effect. If the requested file relative cluster 118 * is beyond the end of file, then the actual number of clusters in the file 119 * is returned in *cnp. This is useful for determining how long a directory is. 120 * If cnp is null, nothing is returned. 121 */ 122 int 123 pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp) 124 { 125 int error; 126 u_long i; 127 u_long cn; 128 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 129 u_long byteoffset; 130 u_long bn; 131 u_long bo; 132 struct buf *bp = NULL; 133 u_long bp_bn = -1; 134 struct msdosfsmount *pmp = dep->de_pmp; 135 u_long bsize; 136 137 KASSERT(bnp != NULL || cnp != NULL || sp != NULL, 138 ("pcbmap: extra call")); 139 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap"); 140 141 cn = dep->de_StartCluster; 142 /* 143 * The "file" that makes up the root directory is contiguous, 144 * permanently allocated, of fixed size, and is not made up of 145 * clusters. If the cluster number is beyond the end of the root 146 * directory, then return the number of clusters in the file. 147 */ 148 if (cn == MSDOSFSROOT) { 149 if (dep->de_Attributes & ATTR_DIRECTORY) { 150 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 151 if (cnp) 152 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 153 return (E2BIG); 154 } 155 if (bnp) 156 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 157 if (cnp) 158 *cnp = MSDOSFSROOT; 159 if (sp) 160 *sp = min(pmp->pm_bpcluster, 161 dep->de_FileSize - de_cn2off(pmp, findcn)); 162 return (0); 163 } else { /* just an empty file */ 164 if (cnp) 165 *cnp = 0; 166 return (E2BIG); 167 } 168 } 169 170 /* 171 * All other files do I/O in cluster sized blocks 172 */ 173 if (sp) 174 *sp = pmp->pm_bpcluster; 175 176 /* 177 * Rummage around in the fat cache, maybe we can avoid tromping 178 * thru every fat entry for the file. And, keep track of how far 179 * off the cache was from where we wanted to be. 180 */ 181 i = 0; 182 fc_lookup(dep, findcn, &i, &cn); 183 184 /* 185 * Handle all other files or directories the normal way. 186 */ 187 for (; i < findcn; i++) { 188 /* 189 * Stop with all reserved clusters, not just with EOF. 190 */ 191 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 192 goto hiteof; 193 byteoffset = FATOFS(pmp, cn); 194 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 195 if (bn != bp_bn) { 196 if (bp) 197 brelse(bp); 198 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 199 if (error) { 200 brelse(bp); 201 return (error); 202 } 203 bp_bn = bn; 204 } 205 prevcn = cn; 206 if (bo >= bsize) { 207 if (bp) 208 brelse(bp); 209 return (EIO); 210 } 211 if (FAT32(pmp)) 212 cn = getulong(&bp->b_data[bo]); 213 else 214 cn = getushort(&bp->b_data[bo]); 215 if (FAT12(pmp) && (prevcn & 1)) 216 cn >>= 4; 217 cn &= pmp->pm_fatmask; 218 219 /* 220 * Force the special cluster numbers 221 * to be the same for all cluster sizes 222 * to let the rest of msdosfs handle 223 * all cases the same. 224 */ 225 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 226 cn |= ~pmp->pm_fatmask; 227 } 228 229 if (!MSDOSFSEOF(pmp, cn)) { 230 if (bp) 231 brelse(bp); 232 if (bnp) 233 *bnp = cntobn(pmp, cn); 234 if (cnp) 235 *cnp = cn; 236 fc_setcache(dep, FC_LASTMAP, i, cn); 237 return (0); 238 } 239 240 hiteof:; 241 if (cnp) 242 *cnp = i; 243 if (bp) 244 brelse(bp); 245 /* update last file cluster entry in the fat cache */ 246 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 247 return (E2BIG); 248 } 249 250 /* 251 * Find the closest entry in the fat cache to the cluster we are looking 252 * for. 253 */ 254 static void 255 fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp) 256 { 257 int i; 258 u_long cn; 259 struct fatcache *closest = 0; 260 261 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup"); 262 263 for (i = 0; i < FC_SIZE; i++) { 264 cn = dep->de_fc[i].fc_frcn; 265 if (cn != FCE_EMPTY && cn <= findcn) { 266 if (closest == 0 || cn > closest->fc_frcn) 267 closest = &dep->de_fc[i]; 268 } 269 } 270 if (closest) { 271 *frcnp = closest->fc_frcn; 272 *fsrcnp = closest->fc_fsrcn; 273 } 274 } 275 276 /* 277 * Purge the fat cache in denode dep of all entries relating to file 278 * relative cluster frcn and beyond. 279 */ 280 void 281 fc_purge(struct denode *dep, u_int frcn) 282 { 283 int i; 284 struct fatcache *fcp; 285 286 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge"); 287 288 fcp = dep->de_fc; 289 for (i = 0; i < FC_SIZE; i++, fcp++) { 290 if (fcp->fc_frcn >= frcn) 291 fcp->fc_frcn = FCE_EMPTY; 292 } 293 } 294 295 /* 296 * Update the fat. 297 * If mirroring the fat, update all copies, with the first copy as last. 298 * Else update only the current fat (ignoring the others). 299 * 300 * pmp - msdosfsmount structure for filesystem to update 301 * bp - addr of modified fat block 302 * fatbn - block number relative to begin of filesystem of the modified fat block. 303 */ 304 static void 305 updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn) 306 { 307 struct buf *bpn; 308 int cleanfat, i; 309 310 #ifdef MSDOSFS_DEBUG 311 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 312 #endif 313 314 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 315 /* 316 * Now copy the block(s) of the modified fat to the other copies of 317 * the fat and write them out. This is faster than reading in the 318 * other fats and then writing them back out. This could tie up 319 * the fat for quite a while. Preventing others from accessing it. 320 * To prevent us from going after the fat quite so much we use 321 * delayed writes, unless they specfied "synchronous" when the 322 * filesystem was mounted. If synch is asked for then use 323 * bwrite()'s and really slow things down. 324 */ 325 if (fatbn != pmp->pm_fatblk || FAT12(pmp)) 326 cleanfat = 0; 327 else if (FAT16(pmp)) 328 cleanfat = 16; 329 else 330 cleanfat = 32; 331 for (i = 1; i < pmp->pm_FATs; i++) { 332 fatbn += pmp->pm_FATsecs; 333 /* getblk() never fails */ 334 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 335 0, 0, 0); 336 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 337 /* Force the clean bit on in the other copies. */ 338 if (cleanfat == 16) 339 ((u_int8_t *)bpn->b_data)[3] |= 0x80; 340 else if (cleanfat == 32) 341 ((u_int8_t *)bpn->b_data)[7] |= 0x08; 342 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 343 bwrite(bpn); 344 else 345 bdwrite(bpn); 346 } 347 } 348 349 /* 350 * Write out the first (or current) fat last. 351 */ 352 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 353 bwrite(bp); 354 else 355 bdwrite(bp); 356 } 357 358 /* 359 * Updating entries in 12 bit fats is a pain in the butt. 360 * 361 * The following picture shows where nibbles go when moving from a 12 bit 362 * cluster number into the appropriate bytes in the FAT. 363 * 364 * byte m byte m+1 byte m+2 365 * +----+----+ +----+----+ +----+----+ 366 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 367 * +----+----+ +----+----+ +----+----+ 368 * 369 * +----+----+----+ +----+----+----+ 370 * | 3 0 1 | | 4 5 2 | 371 * +----+----+----+ +----+----+----+ 372 * cluster n cluster n+1 373 * 374 * Where n is even. m = n + (n >> 2) 375 * 376 */ 377 static __inline void 378 usemap_alloc(struct msdosfsmount *pmp, u_long cn) 379 { 380 381 MSDOSFS_ASSERT_MP_LOCKED(pmp); 382 383 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 384 == 0, ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS, 385 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 386 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 387 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little")); 388 pmp->pm_freeclustercount--; 389 pmp->pm_flags |= MSDOSFS_FSIMOD; 390 } 391 392 static __inline void 393 usemap_free(struct msdosfsmount *pmp, u_long cn) 394 { 395 396 MSDOSFS_ASSERT_MP_LOCKED(pmp); 397 pmp->pm_freeclustercount++; 398 pmp->pm_flags |= MSDOSFS_FSIMOD; 399 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 400 != 0, ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS, 401 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 402 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 403 } 404 405 int 406 clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp) 407 { 408 int error; 409 u_long oldcn; 410 411 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 412 if (error) 413 return (error); 414 /* 415 * If the cluster was successfully marked free, then update 416 * the count of free clusters, and turn off the "allocated" 417 * bit in the "in use" cluster bit map. 418 */ 419 MSDOSFS_LOCK_MP(pmp); 420 usemap_free(pmp, cluster); 421 MSDOSFS_UNLOCK_MP(pmp); 422 if (oldcnp) 423 *oldcnp = oldcn; 424 return (0); 425 } 426 427 /* 428 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 429 * 430 * function - whether to get or set a fat entry 431 * pmp - address of the msdosfsmount structure for the filesystem 432 * whose fat is to be manipulated. 433 * cn - which cluster is of interest 434 * oldcontents - address of a word that is to receive the contents of the 435 * cluster'th entry if this is a get function 436 * newcontents - the new value to be written into the cluster'th element of 437 * the fat if this is a set function. 438 * 439 * This function can also be used to free a cluster by setting the fat entry 440 * for a cluster to 0. 441 * 442 * All copies of the fat are updated if this is a set function. NOTE: If 443 * fatentry() marks a cluster as free it does not update the inusemap in 444 * the msdosfsmount structure. This is left to the caller. 445 */ 446 int 447 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, 448 u_long newcontents) 449 { 450 int error; 451 u_long readcn; 452 u_long bn, bo, bsize, byteoffset; 453 struct buf *bp; 454 455 #ifdef MSDOSFS_DEBUG 456 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 457 function, pmp, cn, oldcontents, newcontents); 458 #endif 459 460 #ifdef DIAGNOSTIC 461 /* 462 * Be sure they asked us to do something. 463 */ 464 if ((function & (FAT_SET | FAT_GET)) == 0) { 465 #ifdef MSDOSFS_DEBUG 466 printf("fatentry(): function code doesn't specify get or set\n"); 467 #endif 468 return (EINVAL); 469 } 470 471 /* 472 * If they asked us to return a cluster number but didn't tell us 473 * where to put it, give them an error. 474 */ 475 if ((function & FAT_GET) && oldcontents == NULL) { 476 #ifdef MSDOSFS_DEBUG 477 printf("fatentry(): get function with no place to put result\n"); 478 #endif 479 return (EINVAL); 480 } 481 #endif 482 483 /* 484 * Be sure the requested cluster is in the filesystem. 485 */ 486 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 487 return (EINVAL); 488 489 byteoffset = FATOFS(pmp, cn); 490 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 491 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 492 if (error) { 493 brelse(bp); 494 return (error); 495 } 496 497 if (function & FAT_GET) { 498 if (FAT32(pmp)) 499 readcn = getulong(&bp->b_data[bo]); 500 else 501 readcn = getushort(&bp->b_data[bo]); 502 if (FAT12(pmp) & (cn & 1)) 503 readcn >>= 4; 504 readcn &= pmp->pm_fatmask; 505 /* map reserved fat entries to same values for all fats */ 506 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 507 readcn |= ~pmp->pm_fatmask; 508 *oldcontents = readcn; 509 } 510 if (function & FAT_SET) { 511 switch (pmp->pm_fatmask) { 512 case FAT12_MASK: 513 readcn = getushort(&bp->b_data[bo]); 514 if (cn & 1) { 515 readcn &= 0x000f; 516 readcn |= newcontents << 4; 517 } else { 518 readcn &= 0xf000; 519 readcn |= newcontents & 0xfff; 520 } 521 putushort(&bp->b_data[bo], readcn); 522 break; 523 case FAT16_MASK: 524 putushort(&bp->b_data[bo], newcontents); 525 break; 526 case FAT32_MASK: 527 /* 528 * According to spec we have to retain the 529 * high order bits of the fat entry. 530 */ 531 readcn = getulong(&bp->b_data[bo]); 532 readcn &= ~FAT32_MASK; 533 readcn |= newcontents & FAT32_MASK; 534 putulong(&bp->b_data[bo], readcn); 535 break; 536 } 537 updatefats(pmp, bp, bn); 538 bp = NULL; 539 pmp->pm_fmod = 1; 540 } 541 if (bp) 542 brelse(bp); 543 return (0); 544 } 545 546 /* 547 * Update a contiguous cluster chain 548 * 549 * pmp - mount point 550 * start - first cluster of chain 551 * count - number of clusters in chain 552 * fillwith - what to write into fat entry of last cluster 553 */ 554 static int 555 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) 556 { 557 int error; 558 u_long bn, bo, bsize, byteoffset, readcn, newc; 559 struct buf *bp; 560 561 #ifdef MSDOSFS_DEBUG 562 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 563 pmp, start, count, fillwith); 564 #endif 565 /* 566 * Be sure the clusters are in the filesystem. 567 */ 568 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 569 return (EINVAL); 570 571 while (count > 0) { 572 byteoffset = FATOFS(pmp, start); 573 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 574 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 575 if (error) { 576 brelse(bp); 577 return (error); 578 } 579 while (count > 0) { 580 start++; 581 newc = --count > 0 ? start : fillwith; 582 switch (pmp->pm_fatmask) { 583 case FAT12_MASK: 584 readcn = getushort(&bp->b_data[bo]); 585 if (start & 1) { 586 readcn &= 0xf000; 587 readcn |= newc & 0xfff; 588 } else { 589 readcn &= 0x000f; 590 readcn |= newc << 4; 591 } 592 putushort(&bp->b_data[bo], readcn); 593 bo++; 594 if (!(start & 1)) 595 bo++; 596 break; 597 case FAT16_MASK: 598 putushort(&bp->b_data[bo], newc); 599 bo += 2; 600 break; 601 case FAT32_MASK: 602 readcn = getulong(&bp->b_data[bo]); 603 readcn &= ~pmp->pm_fatmask; 604 readcn |= newc & pmp->pm_fatmask; 605 putulong(&bp->b_data[bo], readcn); 606 bo += 4; 607 break; 608 } 609 if (bo >= bsize) 610 break; 611 } 612 updatefats(pmp, bp, bn); 613 } 614 pmp->pm_fmod = 1; 615 return (0); 616 } 617 618 /* 619 * Check the length of a free cluster chain starting at start. 620 * 621 * pmp - mount point 622 * start - start of chain 623 * count - maximum interesting length 624 */ 625 static int 626 chainlength(struct msdosfsmount *pmp, u_long start, u_long count) 627 { 628 u_long idx, max_idx; 629 u_int map; 630 u_long len; 631 632 MSDOSFS_ASSERT_MP_LOCKED(pmp); 633 634 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 635 idx = start / N_INUSEBITS; 636 start %= N_INUSEBITS; 637 map = pmp->pm_inusemap[idx]; 638 map &= ~((1 << start) - 1); 639 if (map) { 640 len = ffs(map) - 1 - start; 641 return (len > count ? count : len); 642 } 643 len = N_INUSEBITS - start; 644 if (len >= count) 645 return (count); 646 while (++idx <= max_idx) { 647 if (len >= count) 648 break; 649 map = pmp->pm_inusemap[idx]; 650 if (map) { 651 len += ffs(map) - 1; 652 break; 653 } 654 len += N_INUSEBITS; 655 } 656 return (len > count ? count : len); 657 } 658 659 /* 660 * Allocate contigous free clusters. 661 * 662 * pmp - mount point. 663 * start - start of cluster chain. 664 * count - number of clusters to allocate. 665 * fillwith - put this value into the fat entry for the 666 * last allocated cluster. 667 * retcluster - put the first allocated cluster's number here. 668 * got - how many clusters were actually allocated. 669 */ 670 static int 671 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, 672 u_long fillwith, u_long *retcluster, u_long *got) 673 { 674 int error; 675 u_long cl, n; 676 677 MSDOSFS_ASSERT_MP_LOCKED(pmp); 678 679 for (cl = start, n = count; n-- > 0;) 680 usemap_alloc(pmp, cl++); 681 pmp->pm_nxtfree = start + count; 682 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 683 pmp->pm_nxtfree = CLUST_FIRST; 684 pmp->pm_flags |= MSDOSFS_FSIMOD; 685 error = fatchain(pmp, start, count, fillwith); 686 if (error != 0) 687 return (error); 688 #ifdef MSDOSFS_DEBUG 689 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 690 start, count); 691 #endif 692 if (retcluster) 693 *retcluster = start; 694 if (got) 695 *got = count; 696 return (0); 697 } 698 699 /* 700 * Allocate contiguous free clusters. 701 * 702 * pmp - mount point. 703 * start - preferred start of cluster chain. 704 * count - number of clusters requested. 705 * fillwith - put this value into the fat entry for the 706 * last allocated cluster. 707 * retcluster - put the first allocated cluster's number here. 708 * got - how many clusters were actually allocated. 709 */ 710 int 711 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 712 u_long fillwith, u_long *retcluster, u_long *got) 713 { 714 int error; 715 716 MSDOSFS_LOCK_MP(pmp); 717 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 718 MSDOSFS_UNLOCK_MP(pmp); 719 return (error); 720 } 721 722 static int 723 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 724 u_long fillwith, u_long *retcluster, u_long *got) 725 { 726 u_long idx; 727 u_long len, newst, foundl, cn, l; 728 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 729 u_int map; 730 731 MSDOSFS_ASSERT_MP_LOCKED(pmp); 732 733 #ifdef MSDOSFS_DEBUG 734 printf("clusteralloc(): find %lu clusters\n", count); 735 #endif 736 if (start) { 737 if ((len = chainlength(pmp, start, count)) >= count) 738 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 739 } else 740 len = 0; 741 742 newst = pmp->pm_nxtfree; 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, u_long cluster) 800 { 801 int error; 802 struct buf *bp = NULL; 803 u_long bn, bo, bsize, byteoffset; 804 u_long readcn, lbn = -1; 805 806 MSDOSFS_LOCK_MP(pmp); 807 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 808 byteoffset = FATOFS(pmp, cluster); 809 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 810 if (lbn != bn) { 811 if (bp) 812 updatefats(pmp, bp, lbn); 813 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 814 if (error) { 815 brelse(bp); 816 MSDOSFS_UNLOCK_MP(pmp); 817 return (error); 818 } 819 lbn = bn; 820 } 821 usemap_free(pmp, cluster); 822 switch (pmp->pm_fatmask) { 823 case FAT12_MASK: 824 readcn = getushort(&bp->b_data[bo]); 825 if (cluster & 1) { 826 cluster = readcn >> 4; 827 readcn &= 0x000f; 828 readcn |= MSDOSFSFREE << 4; 829 } else { 830 cluster = readcn; 831 readcn &= 0xf000; 832 readcn |= MSDOSFSFREE & 0xfff; 833 } 834 putushort(&bp->b_data[bo], readcn); 835 break; 836 case FAT16_MASK: 837 cluster = getushort(&bp->b_data[bo]); 838 putushort(&bp->b_data[bo], MSDOSFSFREE); 839 break; 840 case FAT32_MASK: 841 cluster = getulong(&bp->b_data[bo]); 842 putulong(&bp->b_data[bo], 843 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 844 break; 845 } 846 cluster &= pmp->pm_fatmask; 847 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 848 cluster |= pmp->pm_fatmask; 849 } 850 if (bp) 851 updatefats(pmp, bp, bn); 852 MSDOSFS_UNLOCK_MP(pmp); 853 return (0); 854 } 855 856 /* 857 * Read in fat blocks looking for free clusters. For every free cluster 858 * found turn off its corresponding bit in the pm_inusemap. 859 */ 860 int 861 fillinusemap(struct msdosfsmount *pmp) 862 { 863 struct buf *bp = NULL; 864 u_long cn, readcn; 865 int error; 866 u_long bn, bo, bsize, byteoffset; 867 868 MSDOSFS_ASSERT_MP_LOCKED(pmp); 869 870 /* 871 * Mark all clusters in use, we mark the free ones in the fat scan 872 * loop further down. 873 */ 874 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 875 pmp->pm_inusemap[cn] = (u_int)-1; 876 877 /* 878 * Figure how many free clusters are in the filesystem by ripping 879 * through the fat counting the number of entries whose content is 880 * zero. These represent free clusters. 881 */ 882 pmp->pm_freeclustercount = 0; 883 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 884 byteoffset = FATOFS(pmp, cn); 885 bo = byteoffset % pmp->pm_fatblocksize; 886 if (!bo || !bp) { 887 /* Read new FAT block */ 888 if (bp) 889 brelse(bp); 890 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 891 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 892 if (error) { 893 brelse(bp); 894 return (error); 895 } 896 } 897 if (FAT32(pmp)) 898 readcn = getulong(&bp->b_data[bo]); 899 else 900 readcn = getushort(&bp->b_data[bo]); 901 if (FAT12(pmp) && (cn & 1)) 902 readcn >>= 4; 903 readcn &= pmp->pm_fatmask; 904 905 if (readcn == 0) 906 usemap_free(pmp, cn); 907 } 908 if (bp != NULL) 909 brelse(bp); 910 return (0); 911 } 912 913 /* 914 * Allocate a new cluster and chain it onto the end of the file. 915 * 916 * dep - the file to extend 917 * count - number of clusters to allocate 918 * bpp - where to return the address of the buf header for the first new 919 * file block 920 * ncp - where to put cluster number of the first newly allocated cluster 921 * If this pointer is 0, do not return the cluster number. 922 * flags - see fat.h 923 * 924 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 925 * the de_flag field of the denode and it does not change the de_FileSize 926 * field. This is left for the caller to do. 927 */ 928 int 929 extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp, 930 int flags) 931 { 932 int error; 933 u_long frcn; 934 u_long cn, got; 935 struct msdosfsmount *pmp = dep->de_pmp; 936 struct buf *bp; 937 daddr_t blkno; 938 939 /* 940 * Don't try to extend the root directory 941 */ 942 if (dep->de_StartCluster == MSDOSFSROOT 943 && (dep->de_Attributes & ATTR_DIRECTORY)) { 944 #ifdef MSDOSFS_DEBUG 945 printf("extendfile(): attempt to extend root directory\n"); 946 #endif 947 return (ENOSPC); 948 } 949 950 /* 951 * If the "file's last cluster" cache entry is empty, and the file 952 * is not empty, then fill the cache entry by calling pcbmap(). 953 */ 954 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 955 dep->de_StartCluster != 0) { 956 error = pcbmap(dep, 0xffff, 0, &cn, 0); 957 /* we expect it to return E2BIG */ 958 if (error != E2BIG) 959 return (error); 960 } 961 962 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 963 dep->de_fc[FC_LASTFC].fc_frcn; 964 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 965 dep->de_fc[FC_LASTFC].fc_fsrcn; 966 while (count > 0) { 967 /* 968 * Allocate a new cluster chain and cat onto the end of the 969 * file. * If the file is empty we make de_StartCluster point 970 * to the new block. Note that de_StartCluster being 0 is 971 * sufficient to be sure the file is empty since we exclude 972 * attempts to extend the root directory above, and the root 973 * dir is the only file with a startcluster of 0 that has 974 * blocks allocated (sort of). 975 */ 976 if (dep->de_StartCluster == 0) 977 cn = 0; 978 else 979 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 980 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 981 if (error) 982 return (error); 983 984 count -= got; 985 986 /* 987 * Give them the filesystem relative cluster number if they want 988 * it. 989 */ 990 if (ncp) { 991 *ncp = cn; 992 ncp = NULL; 993 } 994 995 if (dep->de_StartCluster == 0) { 996 dep->de_StartCluster = cn; 997 frcn = 0; 998 } else { 999 error = fatentry(FAT_SET, pmp, 1000 dep->de_fc[FC_LASTFC].fc_fsrcn, 1001 0, cn); 1002 if (error) { 1003 clusterfree(pmp, cn, NULL); 1004 return (error); 1005 } 1006 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1007 } 1008 1009 /* 1010 * Update the "last cluster of the file" entry in the denode's fat 1011 * cache. 1012 */ 1013 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1014 1015 if (flags & DE_CLEAR) { 1016 while (got-- > 0) { 1017 /* 1018 * Get the buf header for the new block of the file. 1019 */ 1020 if (dep->de_Attributes & ATTR_DIRECTORY) 1021 bp = getblk(pmp->pm_devvp, 1022 cntobn(pmp, cn++), 1023 pmp->pm_bpcluster, 0, 0, 0); 1024 else { 1025 bp = getblk(DETOV(dep), 1026 frcn++, 1027 pmp->pm_bpcluster, 0, 0, 0); 1028 /* 1029 * Do the bmap now, as in msdosfs_write 1030 */ 1031 if (pcbmap(dep, 1032 bp->b_lblkno, 1033 &blkno, 0, 0)) 1034 bp->b_blkno = -1; 1035 if (bp->b_blkno == -1) 1036 panic("extendfile: pcbmap"); 1037 else 1038 bp->b_blkno = blkno; 1039 } 1040 vfs_bio_clrbuf(bp); 1041 if (bpp) { 1042 *bpp = bp; 1043 bpp = NULL; 1044 } else 1045 bdwrite(bp); 1046 } 1047 } 1048 } 1049 1050 return (0); 1051 } 1052 1053 /*- 1054 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1055 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1056 * this bit is not defined for FAT12 volumes, which are always assumed to 1057 * be clean. 1058 * 1059 * The fatentry() routine only works on cluster numbers that a file could 1060 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1061 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1062 * 1063 * Inputs: 1064 * pmp The MS-DOS volume to mark 1065 * dirty Non-zero if the volume should be marked dirty; zero if it 1066 * should be marked clean 1067 * 1068 * Result: 1069 * 0 Success 1070 * EROFS Volume is read-only 1071 * ? (other errors from called routines) 1072 */ 1073 int 1074 markvoldirty(struct msdosfsmount *pmp, int dirty) 1075 { 1076 struct buf *bp; 1077 u_long bn, bo, bsize, byteoffset, fatval; 1078 int error; 1079 1080 /* 1081 * FAT12 does not support a "clean" bit, so don't do anything for 1082 * FAT12. 1083 */ 1084 if (FAT12(pmp)) 1085 return (0); 1086 1087 /* Can't change the bit on a read-only filesystem. */ 1088 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1089 return (EROFS); 1090 1091 /* 1092 * Fetch the block containing the FAT entry. It is given by the 1093 * pseudo-cluster 1. 1094 */ 1095 byteoffset = FATOFS(pmp, 1); 1096 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1097 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1098 if (error) { 1099 brelse(bp); 1100 return (error); 1101 } 1102 1103 /* 1104 * Get the current value of the FAT entry and set/clear the relevant 1105 * bit. Dirty means clear the "clean" bit; clean means set the 1106 * "clean" bit. 1107 */ 1108 if (FAT32(pmp)) { 1109 /* FAT32 uses bit 27. */ 1110 fatval = getulong(&bp->b_data[bo]); 1111 if (dirty) 1112 fatval &= 0xF7FFFFFF; 1113 else 1114 fatval |= 0x08000000; 1115 putulong(&bp->b_data[bo], fatval); 1116 } else { 1117 /* Must be FAT16; use bit 15. */ 1118 fatval = getushort(&bp->b_data[bo]); 1119 if (dirty) 1120 fatval &= 0x7FFF; 1121 else 1122 fatval |= 0x8000; 1123 putushort(&bp->b_data[bo], fatval); 1124 } 1125 1126 /* Write out the modified FAT block synchronously. */ 1127 return (bwrite(bp)); 1128 } 1129