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 #define FULL_RUN ((u_int)0xffffffff) 64 65 static int chainalloc(struct msdosfsmount *pmp, u_long start, 66 u_long count, u_long fillwith, u_long *retcluster, 67 u_long *got); 68 static int chainlength(struct msdosfsmount *pmp, u_long start, 69 u_long count); 70 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 71 u_long *sizep, u_long *bop); 72 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 73 u_long fillwith); 74 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 75 u_long *fsrcnp); 76 static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 77 u_long fatbn); 78 static __inline void 79 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 80 static __inline void 81 usemap_free(struct msdosfsmount *pmp, u_long cn); 82 static int clusteralloc1(struct msdosfsmount *pmp, u_long start, 83 u_long count, u_long fillwith, u_long *retcluster, 84 u_long *got); 85 86 static void 87 fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep, 88 u_long *bop) 89 { 90 u_long bn, size; 91 92 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 93 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 94 * DEV_BSIZE; 95 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 96 97 if (bnp) 98 *bnp = bn; 99 if (sizep) 100 *sizep = size; 101 if (bop) 102 *bop = ofs % pmp->pm_fatblocksize; 103 } 104 105 /* 106 * Map the logical cluster number of a file into a physical disk sector 107 * that is filesystem relative. 108 * 109 * dep - address of denode representing the file of interest 110 * findcn - file relative cluster whose filesystem relative cluster number 111 * and/or block number are/is to be found 112 * bnp - address of where to place the filesystem relative block number. 113 * If this pointer is null then don't return this quantity. 114 * cnp - address of where to place the filesystem relative cluster number. 115 * If this pointer is null then don't return this quantity. 116 * sp - pointer to returned block size 117 * 118 * NOTE: Either bnp or cnp must be non-null. 119 * This function has one side effect. If the requested file relative cluster 120 * is beyond the end of file, then the actual number of clusters in the file 121 * is returned in *cnp. This is useful for determining how long a directory is. 122 * If cnp is null, nothing is returned. 123 */ 124 int 125 pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp) 126 { 127 int error; 128 u_long i; 129 u_long cn; 130 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 131 u_long byteoffset; 132 u_long bn; 133 u_long bo; 134 struct buf *bp = NULL; 135 u_long bp_bn = -1; 136 struct msdosfsmount *pmp = dep->de_pmp; 137 u_long bsize; 138 139 KASSERT(bnp != NULL || cnp != NULL || sp != NULL, 140 ("pcbmap: extra call")); 141 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap"); 142 143 cn = dep->de_StartCluster; 144 /* 145 * The "file" that makes up the root directory is contiguous, 146 * permanently allocated, of fixed size, and is not made up of 147 * clusters. If the cluster number is beyond the end of the root 148 * directory, then return the number of clusters in the file. 149 */ 150 if (cn == MSDOSFSROOT) { 151 if (dep->de_Attributes & ATTR_DIRECTORY) { 152 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 153 if (cnp) 154 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 155 return (E2BIG); 156 } 157 if (bnp) 158 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 159 if (cnp) 160 *cnp = MSDOSFSROOT; 161 if (sp) 162 *sp = min(pmp->pm_bpcluster, 163 dep->de_FileSize - de_cn2off(pmp, findcn)); 164 return (0); 165 } else { /* just an empty file */ 166 if (cnp) 167 *cnp = 0; 168 return (E2BIG); 169 } 170 } 171 172 /* 173 * All other files do I/O in cluster sized blocks 174 */ 175 if (sp) 176 *sp = pmp->pm_bpcluster; 177 178 /* 179 * Rummage around in the fat cache, maybe we can avoid tromping 180 * through every fat entry for the file. And, keep track of how far 181 * off the cache was from where we wanted to be. 182 */ 183 i = 0; 184 fc_lookup(dep, findcn, &i, &cn); 185 186 /* 187 * Handle all other files or directories the normal way. 188 */ 189 for (; i < findcn; i++) { 190 /* 191 * Stop with all reserved clusters, not just with EOF. 192 */ 193 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 194 goto hiteof; 195 byteoffset = FATOFS(pmp, cn); 196 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 197 if (bn != bp_bn) { 198 if (bp) 199 brelse(bp); 200 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 201 if (error) { 202 brelse(bp); 203 return (error); 204 } 205 bp_bn = bn; 206 } 207 prevcn = cn; 208 if (bo >= bsize) { 209 if (bp) 210 brelse(bp); 211 return (EIO); 212 } 213 if (FAT32(pmp)) 214 cn = getulong(&bp->b_data[bo]); 215 else 216 cn = getushort(&bp->b_data[bo]); 217 if (FAT12(pmp) && (prevcn & 1)) 218 cn >>= 4; 219 cn &= pmp->pm_fatmask; 220 221 /* 222 * Force the special cluster numbers 223 * to be the same for all cluster sizes 224 * to let the rest of msdosfs handle 225 * all cases the same. 226 */ 227 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 228 cn |= ~pmp->pm_fatmask; 229 } 230 231 if (!MSDOSFSEOF(pmp, cn)) { 232 if (bp) 233 brelse(bp); 234 if (bnp) 235 *bnp = cntobn(pmp, cn); 236 if (cnp) 237 *cnp = cn; 238 fc_setcache(dep, FC_LASTMAP, i, cn); 239 return (0); 240 } 241 242 hiteof:; 243 if (cnp) 244 *cnp = i; 245 if (bp) 246 brelse(bp); 247 /* update last file cluster entry in the fat cache */ 248 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 249 return (E2BIG); 250 } 251 252 /* 253 * Find the closest entry in the fat cache to the cluster we are looking 254 * for. 255 */ 256 static void 257 fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp) 258 { 259 int i; 260 u_long cn; 261 struct fatcache *closest = NULL; 262 263 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup"); 264 265 for (i = 0; i < FC_SIZE; i++) { 266 cn = dep->de_fc[i].fc_frcn; 267 if (cn != FCE_EMPTY && cn <= findcn) { 268 if (closest == NULL || cn > closest->fc_frcn) 269 closest = &dep->de_fc[i]; 270 } 271 } 272 if (closest) { 273 *frcnp = closest->fc_frcn; 274 *fsrcnp = closest->fc_fsrcn; 275 } 276 } 277 278 /* 279 * Purge the fat cache in denode dep of all entries relating to file 280 * relative cluster frcn and beyond. 281 */ 282 void 283 fc_purge(struct denode *dep, u_int frcn) 284 { 285 int i; 286 struct fatcache *fcp; 287 288 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge"); 289 290 fcp = dep->de_fc; 291 for (i = 0; i < FC_SIZE; i++, fcp++) { 292 if (fcp->fc_frcn >= frcn) 293 fcp->fc_frcn = FCE_EMPTY; 294 } 295 } 296 297 /* 298 * Update the fat. 299 * If mirroring the fat, update all copies, with the first copy as last. 300 * Else update only the current fat (ignoring the others). 301 * 302 * pmp - msdosfsmount structure for filesystem to update 303 * bp - addr of modified fat block 304 * fatbn - block number relative to begin of filesystem of the modified fat block. 305 */ 306 static void 307 updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn) 308 { 309 struct buf *bpn; 310 int cleanfat, i; 311 312 #ifdef MSDOSFS_DEBUG 313 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 314 #endif 315 316 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 317 /* 318 * Now copy the block(s) of the modified fat to the other copies of 319 * the fat and write them out. This is faster than reading in the 320 * other fats and then writing them back out. This could tie up 321 * the fat for quite a while. Preventing others from accessing it. 322 * To prevent us from going after the fat quite so much we use 323 * delayed writes, unless they specfied "synchronous" when the 324 * filesystem was mounted. If synch is asked for then use 325 * bwrite()'s and really slow things down. 326 */ 327 if (fatbn != pmp->pm_fatblk || FAT12(pmp)) 328 cleanfat = 0; 329 else if (FAT16(pmp)) 330 cleanfat = 16; 331 else 332 cleanfat = 32; 333 for (i = 1; i < pmp->pm_FATs; i++) { 334 fatbn += pmp->pm_FATsecs; 335 /* getblk() never fails */ 336 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 337 0, 0, 0); 338 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 339 /* Force the clean bit on in the other copies. */ 340 if (cleanfat == 16) 341 ((u_int8_t *)bpn->b_data)[3] |= 0x80; 342 else if (cleanfat == 32) 343 ((u_int8_t *)bpn->b_data)[7] |= 0x08; 344 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 345 bwrite(bpn); 346 else 347 bdwrite(bpn); 348 } 349 } 350 351 /* 352 * Write out the first (or current) fat last. 353 */ 354 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 355 bwrite(bp); 356 else 357 bdwrite(bp); 358 } 359 360 /* 361 * Updating entries in 12 bit fats is a pain in the butt. 362 * 363 * The following picture shows where nibbles go when moving from a 12 bit 364 * cluster number into the appropriate bytes in the FAT. 365 * 366 * byte m byte m+1 byte m+2 367 * +----+----+ +----+----+ +----+----+ 368 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 369 * +----+----+ +----+----+ +----+----+ 370 * 371 * +----+----+----+ +----+----+----+ 372 * | 3 0 1 | | 4 5 2 | 373 * +----+----+----+ +----+----+----+ 374 * cluster n cluster n+1 375 * 376 * Where n is even. m = n + (n >> 2) 377 * 378 */ 379 static __inline void 380 usemap_alloc(struct msdosfsmount *pmp, u_long cn) 381 { 382 383 MSDOSFS_ASSERT_MP_LOCKED(pmp); 384 385 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 386 pmp->pm_maxcluster)); 387 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 388 ("usemap_alloc on ro msdosfs mount")); 389 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 390 == 0, ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS, 391 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 392 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 393 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little")); 394 pmp->pm_freeclustercount--; 395 pmp->pm_flags |= MSDOSFS_FSIMOD; 396 } 397 398 static __inline void 399 usemap_free(struct msdosfsmount *pmp, u_long cn) 400 { 401 402 MSDOSFS_ASSERT_MP_LOCKED(pmp); 403 404 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 405 pmp->pm_maxcluster)); 406 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 407 ("usemap_free on ro msdosfs mount")); 408 pmp->pm_freeclustercount++; 409 pmp->pm_flags |= MSDOSFS_FSIMOD; 410 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 411 != 0, ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS, 412 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 413 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 414 } 415 416 int 417 clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp) 418 { 419 int error; 420 u_long oldcn; 421 422 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 423 if (error) 424 return (error); 425 /* 426 * If the cluster was successfully marked free, then update 427 * the count of free clusters, and turn off the "allocated" 428 * bit in the "in use" cluster bit map. 429 */ 430 MSDOSFS_LOCK_MP(pmp); 431 usemap_free(pmp, cluster); 432 MSDOSFS_UNLOCK_MP(pmp); 433 if (oldcnp) 434 *oldcnp = oldcn; 435 return (0); 436 } 437 438 /* 439 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 440 * 441 * function - whether to get or set a fat entry 442 * pmp - address of the msdosfsmount structure for the filesystem 443 * whose fat is to be manipulated. 444 * cn - which cluster is of interest 445 * oldcontents - address of a word that is to receive the contents of the 446 * cluster'th entry if this is a get function 447 * newcontents - the new value to be written into the cluster'th element of 448 * the fat if this is a set function. 449 * 450 * This function can also be used to free a cluster by setting the fat entry 451 * for a cluster to 0. 452 * 453 * All copies of the fat are updated if this is a set function. NOTE: If 454 * fatentry() marks a cluster as free it does not update the inusemap in 455 * the msdosfsmount structure. This is left to the caller. 456 */ 457 int 458 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, 459 u_long newcontents) 460 { 461 int error; 462 u_long readcn; 463 u_long bn, bo, bsize, byteoffset; 464 struct buf *bp; 465 466 #ifdef MSDOSFS_DEBUG 467 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 468 function, pmp, cn, oldcontents, newcontents); 469 #endif 470 471 #ifdef DIAGNOSTIC 472 /* 473 * Be sure they asked us to do something. 474 */ 475 if ((function & (FAT_SET | FAT_GET)) == 0) { 476 #ifdef MSDOSFS_DEBUG 477 printf("fatentry(): function code doesn't specify get or set\n"); 478 #endif 479 return (EINVAL); 480 } 481 482 /* 483 * If they asked us to return a cluster number but didn't tell us 484 * where to put it, give them an error. 485 */ 486 if ((function & FAT_GET) && oldcontents == NULL) { 487 #ifdef MSDOSFS_DEBUG 488 printf("fatentry(): get function with no place to put result\n"); 489 #endif 490 return (EINVAL); 491 } 492 #endif 493 494 /* 495 * Be sure the requested cluster is in the filesystem. 496 */ 497 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 498 return (EINVAL); 499 500 byteoffset = FATOFS(pmp, cn); 501 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 502 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 503 if (error) { 504 brelse(bp); 505 return (error); 506 } 507 508 if (function & FAT_GET) { 509 if (FAT32(pmp)) 510 readcn = getulong(&bp->b_data[bo]); 511 else 512 readcn = getushort(&bp->b_data[bo]); 513 if (FAT12(pmp) & (cn & 1)) 514 readcn >>= 4; 515 readcn &= pmp->pm_fatmask; 516 /* map reserved fat entries to same values for all fats */ 517 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 518 readcn |= ~pmp->pm_fatmask; 519 *oldcontents = readcn; 520 } 521 if (function & FAT_SET) { 522 switch (pmp->pm_fatmask) { 523 case FAT12_MASK: 524 readcn = getushort(&bp->b_data[bo]); 525 if (cn & 1) { 526 readcn &= 0x000f; 527 readcn |= newcontents << 4; 528 } else { 529 readcn &= 0xf000; 530 readcn |= newcontents & 0xfff; 531 } 532 putushort(&bp->b_data[bo], readcn); 533 break; 534 case FAT16_MASK: 535 putushort(&bp->b_data[bo], newcontents); 536 break; 537 case FAT32_MASK: 538 /* 539 * According to spec we have to retain the 540 * high order bits of the fat entry. 541 */ 542 readcn = getulong(&bp->b_data[bo]); 543 readcn &= ~FAT32_MASK; 544 readcn |= newcontents & FAT32_MASK; 545 putulong(&bp->b_data[bo], readcn); 546 break; 547 } 548 updatefats(pmp, bp, bn); 549 bp = NULL; 550 pmp->pm_fmod = 1; 551 } 552 if (bp) 553 brelse(bp); 554 return (0); 555 } 556 557 /* 558 * Update a contiguous cluster chain 559 * 560 * pmp - mount point 561 * start - first cluster of chain 562 * count - number of clusters in chain 563 * fillwith - what to write into fat entry of last cluster 564 */ 565 static int 566 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) 567 { 568 int error; 569 u_long bn, bo, bsize, byteoffset, readcn, newc; 570 struct buf *bp; 571 572 #ifdef MSDOSFS_DEBUG 573 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 574 pmp, start, count, fillwith); 575 #endif 576 /* 577 * Be sure the clusters are in the filesystem. 578 */ 579 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 580 return (EINVAL); 581 582 while (count > 0) { 583 byteoffset = FATOFS(pmp, start); 584 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 585 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 586 if (error) { 587 brelse(bp); 588 return (error); 589 } 590 while (count > 0) { 591 start++; 592 newc = --count > 0 ? start : fillwith; 593 switch (pmp->pm_fatmask) { 594 case FAT12_MASK: 595 readcn = getushort(&bp->b_data[bo]); 596 if (start & 1) { 597 readcn &= 0xf000; 598 readcn |= newc & 0xfff; 599 } else { 600 readcn &= 0x000f; 601 readcn |= newc << 4; 602 } 603 putushort(&bp->b_data[bo], readcn); 604 bo++; 605 if (!(start & 1)) 606 bo++; 607 break; 608 case FAT16_MASK: 609 putushort(&bp->b_data[bo], newc); 610 bo += 2; 611 break; 612 case FAT32_MASK: 613 readcn = getulong(&bp->b_data[bo]); 614 readcn &= ~pmp->pm_fatmask; 615 readcn |= newc & pmp->pm_fatmask; 616 putulong(&bp->b_data[bo], readcn); 617 bo += 4; 618 break; 619 } 620 if (bo >= bsize) 621 break; 622 } 623 updatefats(pmp, bp, bn); 624 } 625 pmp->pm_fmod = 1; 626 return (0); 627 } 628 629 /* 630 * Check the length of a free cluster chain starting at start. 631 * 632 * pmp - mount point 633 * start - start of chain 634 * count - maximum interesting length 635 */ 636 static int 637 chainlength(struct msdosfsmount *pmp, u_long start, u_long count) 638 { 639 u_long idx, max_idx; 640 u_int map; 641 u_long len; 642 643 MSDOSFS_ASSERT_MP_LOCKED(pmp); 644 645 if (start > pmp->pm_maxcluster) 646 return (0); 647 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 648 idx = start / N_INUSEBITS; 649 start %= N_INUSEBITS; 650 map = pmp->pm_inusemap[idx]; 651 map &= ~((1 << start) - 1); 652 if (map) { 653 len = ffs(map) - 1 - start; 654 len = MIN(len, count); 655 if (start + len > pmp->pm_maxcluster) 656 len = pmp->pm_maxcluster - start + 1; 657 return (len); 658 } 659 len = N_INUSEBITS - start; 660 if (len >= count) { 661 len = count; 662 if (start + len > pmp->pm_maxcluster) 663 len = pmp->pm_maxcluster - start + 1; 664 return (len); 665 } 666 while (++idx <= max_idx) { 667 if (len >= count) 668 break; 669 map = pmp->pm_inusemap[idx]; 670 if (map) { 671 len += ffs(map) - 1; 672 break; 673 } 674 len += N_INUSEBITS; 675 } 676 len = MIN(len, count); 677 if (start + len > pmp->pm_maxcluster) 678 len = pmp->pm_maxcluster - start + 1; 679 return (len); 680 } 681 682 /* 683 * Allocate contigous free clusters. 684 * 685 * pmp - mount point. 686 * start - start of cluster chain. 687 * count - number of clusters to allocate. 688 * fillwith - put this value into the fat entry for the 689 * last allocated cluster. 690 * retcluster - put the first allocated cluster's number here. 691 * got - how many clusters were actually allocated. 692 */ 693 static int 694 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, 695 u_long fillwith, u_long *retcluster, u_long *got) 696 { 697 int error; 698 u_long cl, n; 699 700 MSDOSFS_ASSERT_MP_LOCKED(pmp); 701 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 702 ("chainalloc on ro msdosfs mount")); 703 704 for (cl = start, n = count; n-- > 0;) 705 usemap_alloc(pmp, cl++); 706 pmp->pm_nxtfree = start + count; 707 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 708 pmp->pm_nxtfree = CLUST_FIRST; 709 pmp->pm_flags |= MSDOSFS_FSIMOD; 710 error = fatchain(pmp, start, count, fillwith); 711 if (error != 0) { 712 for (cl = start, n = count; n-- > 0;) 713 usemap_free(pmp, cl++); 714 return (error); 715 } 716 #ifdef MSDOSFS_DEBUG 717 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 718 start, count); 719 #endif 720 if (retcluster) 721 *retcluster = start; 722 if (got) 723 *got = count; 724 return (0); 725 } 726 727 /* 728 * Allocate contiguous free clusters. 729 * 730 * pmp - mount point. 731 * start - preferred start of cluster chain. 732 * count - number of clusters requested. 733 * fillwith - put this value into the fat entry for the 734 * last allocated cluster. 735 * retcluster - put the first allocated cluster's number here. 736 * got - how many clusters were actually allocated. 737 */ 738 int 739 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 740 u_long fillwith, u_long *retcluster, u_long *got) 741 { 742 int error; 743 744 MSDOSFS_LOCK_MP(pmp); 745 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 746 MSDOSFS_UNLOCK_MP(pmp); 747 return (error); 748 } 749 750 static int 751 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 752 u_long fillwith, u_long *retcluster, u_long *got) 753 { 754 u_long idx; 755 u_long len, newst, foundl, cn, l; 756 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 757 u_int map; 758 759 MSDOSFS_ASSERT_MP_LOCKED(pmp); 760 761 #ifdef MSDOSFS_DEBUG 762 printf("clusteralloc(): find %lu clusters\n", count); 763 #endif 764 if (start) { 765 if ((len = chainlength(pmp, start, count)) >= count) 766 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 767 } else 768 len = 0; 769 770 newst = pmp->pm_nxtfree; 771 foundl = 0; 772 773 for (cn = newst; cn <= pmp->pm_maxcluster;) { 774 idx = cn / N_INUSEBITS; 775 map = pmp->pm_inusemap[idx]; 776 map |= (1 << (cn % N_INUSEBITS)) - 1; 777 if (map != FULL_RUN) { 778 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 779 if ((l = chainlength(pmp, cn, count)) >= count) 780 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 781 if (l > foundl) { 782 foundcn = cn; 783 foundl = l; 784 } 785 cn += l + 1; 786 continue; 787 } 788 cn += N_INUSEBITS - cn % N_INUSEBITS; 789 } 790 for (cn = 0; cn < newst;) { 791 idx = cn / N_INUSEBITS; 792 map = pmp->pm_inusemap[idx]; 793 map |= (1 << (cn % N_INUSEBITS)) - 1; 794 if (map != FULL_RUN) { 795 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 796 if ((l = chainlength(pmp, cn, count)) >= count) 797 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 798 if (l > foundl) { 799 foundcn = cn; 800 foundl = l; 801 } 802 cn += l + 1; 803 continue; 804 } 805 cn += N_INUSEBITS - cn % N_INUSEBITS; 806 } 807 808 if (!foundl) 809 return (ENOSPC); 810 811 if (len) 812 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 813 else 814 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 815 } 816 817 818 /* 819 * Free a chain of clusters. 820 * 821 * pmp - address of the msdosfs mount structure for the filesystem 822 * containing the cluster chain to be freed. 823 * startcluster - number of the 1st cluster in the chain of clusters to be 824 * freed. 825 */ 826 int 827 freeclusterchain(struct msdosfsmount *pmp, u_long cluster) 828 { 829 int error; 830 struct buf *bp = NULL; 831 u_long bn, bo, bsize, byteoffset; 832 u_long readcn, lbn = -1; 833 834 MSDOSFS_LOCK_MP(pmp); 835 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 836 byteoffset = FATOFS(pmp, cluster); 837 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 838 if (lbn != bn) { 839 if (bp) 840 updatefats(pmp, bp, lbn); 841 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 842 if (error) { 843 brelse(bp); 844 MSDOSFS_UNLOCK_MP(pmp); 845 return (error); 846 } 847 lbn = bn; 848 } 849 usemap_free(pmp, cluster); 850 switch (pmp->pm_fatmask) { 851 case FAT12_MASK: 852 readcn = getushort(&bp->b_data[bo]); 853 if (cluster & 1) { 854 cluster = readcn >> 4; 855 readcn &= 0x000f; 856 readcn |= MSDOSFSFREE << 4; 857 } else { 858 cluster = readcn; 859 readcn &= 0xf000; 860 readcn |= MSDOSFSFREE & 0xfff; 861 } 862 putushort(&bp->b_data[bo], readcn); 863 break; 864 case FAT16_MASK: 865 cluster = getushort(&bp->b_data[bo]); 866 putushort(&bp->b_data[bo], MSDOSFSFREE); 867 break; 868 case FAT32_MASK: 869 cluster = getulong(&bp->b_data[bo]); 870 putulong(&bp->b_data[bo], 871 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 872 break; 873 } 874 cluster &= pmp->pm_fatmask; 875 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 876 cluster |= pmp->pm_fatmask; 877 } 878 if (bp) 879 updatefats(pmp, bp, bn); 880 MSDOSFS_UNLOCK_MP(pmp); 881 return (0); 882 } 883 884 /* 885 * Read in fat blocks looking for free clusters. For every free cluster 886 * found turn off its corresponding bit in the pm_inusemap. 887 */ 888 int 889 fillinusemap(struct msdosfsmount *pmp) 890 { 891 struct buf *bp = NULL; 892 u_long cn, readcn; 893 int error; 894 u_long bn, bo, bsize, byteoffset; 895 896 MSDOSFS_ASSERT_MP_LOCKED(pmp); 897 898 /* 899 * Mark all clusters in use, we mark the free ones in the fat scan 900 * loop further down. 901 */ 902 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 903 pmp->pm_inusemap[cn] = FULL_RUN; 904 905 /* 906 * Figure how many free clusters are in the filesystem by ripping 907 * through the fat counting the number of entries whose content is 908 * zero. These represent free clusters. 909 */ 910 pmp->pm_freeclustercount = 0; 911 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 912 byteoffset = FATOFS(pmp, cn); 913 bo = byteoffset % pmp->pm_fatblocksize; 914 if (!bo || !bp) { 915 /* Read new FAT block */ 916 if (bp) 917 brelse(bp); 918 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 919 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 920 if (error) { 921 brelse(bp); 922 return (error); 923 } 924 } 925 if (FAT32(pmp)) 926 readcn = getulong(&bp->b_data[bo]); 927 else 928 readcn = getushort(&bp->b_data[bo]); 929 if (FAT12(pmp) && (cn & 1)) 930 readcn >>= 4; 931 readcn &= pmp->pm_fatmask; 932 933 if (readcn == CLUST_FREE) 934 usemap_free(pmp, cn); 935 } 936 if (bp != NULL) 937 brelse(bp); 938 939 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster + 940 N_INUSEBITS) / N_INUSEBITS; cn++) 941 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 942 943 return (0); 944 } 945 946 /* 947 * Allocate a new cluster and chain it onto the end of the file. 948 * 949 * dep - the file to extend 950 * count - number of clusters to allocate 951 * bpp - where to return the address of the buf header for the first new 952 * file block 953 * ncp - where to put cluster number of the first newly allocated cluster 954 * If this pointer is 0, do not return the cluster number. 955 * flags - see fat.h 956 * 957 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 958 * the de_flag field of the denode and it does not change the de_FileSize 959 * field. This is left for the caller to do. 960 */ 961 int 962 extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp, 963 int flags) 964 { 965 int error; 966 u_long frcn; 967 u_long cn, got; 968 struct msdosfsmount *pmp = dep->de_pmp; 969 struct buf *bp; 970 daddr_t blkno; 971 972 /* 973 * Don't try to extend the root directory 974 */ 975 if (dep->de_StartCluster == MSDOSFSROOT 976 && (dep->de_Attributes & ATTR_DIRECTORY)) { 977 #ifdef MSDOSFS_DEBUG 978 printf("extendfile(): attempt to extend root directory\n"); 979 #endif 980 return (ENOSPC); 981 } 982 983 /* 984 * If the "file's last cluster" cache entry is empty, and the file 985 * is not empty, then fill the cache entry by calling pcbmap(). 986 */ 987 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 988 dep->de_StartCluster != 0) { 989 error = pcbmap(dep, 0xffff, 0, &cn, 0); 990 /* we expect it to return E2BIG */ 991 if (error != E2BIG) 992 return (error); 993 } 994 995 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 996 dep->de_fc[FC_LASTFC].fc_frcn; 997 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 998 dep->de_fc[FC_LASTFC].fc_fsrcn; 999 while (count > 0) { 1000 /* 1001 * Allocate a new cluster chain and cat onto the end of the 1002 * file. 1003 * If the file is empty we make de_StartCluster point 1004 * to the new block. Note that de_StartCluster being 1005 * 0 is sufficient to be sure the file is empty since 1006 * we exclude attempts to extend the root directory 1007 * above, and the root dir is the only file with a 1008 * startcluster of 0 that has blocks allocated (sort 1009 * of). 1010 */ 1011 if (dep->de_StartCluster == 0) 1012 cn = 0; 1013 else 1014 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1015 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1016 if (error) 1017 return (error); 1018 1019 count -= got; 1020 1021 /* 1022 * Give them the filesystem relative cluster number if they want 1023 * it. 1024 */ 1025 if (ncp) { 1026 *ncp = cn; 1027 ncp = NULL; 1028 } 1029 1030 if (dep->de_StartCluster == 0) { 1031 dep->de_StartCluster = cn; 1032 frcn = 0; 1033 } else { 1034 error = fatentry(FAT_SET, pmp, 1035 dep->de_fc[FC_LASTFC].fc_fsrcn, 1036 0, cn); 1037 if (error) { 1038 clusterfree(pmp, cn, NULL); 1039 return (error); 1040 } 1041 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1042 } 1043 1044 /* 1045 * Update the "last cluster of the file" entry in the denode's fat 1046 * cache. 1047 */ 1048 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1049 1050 if (flags & DE_CLEAR) { 1051 while (got-- > 0) { 1052 /* 1053 * Get the buf header for the new block of the file. 1054 */ 1055 if (dep->de_Attributes & ATTR_DIRECTORY) 1056 bp = getblk(pmp->pm_devvp, 1057 cntobn(pmp, cn++), 1058 pmp->pm_bpcluster, 0, 0, 0); 1059 else { 1060 bp = getblk(DETOV(dep), 1061 frcn++, 1062 pmp->pm_bpcluster, 0, 0, 0); 1063 /* 1064 * Do the bmap now, as in msdosfs_write 1065 */ 1066 if (pcbmap(dep, 1067 bp->b_lblkno, 1068 &blkno, 0, 0)) 1069 bp->b_blkno = -1; 1070 if (bp->b_blkno == -1) 1071 panic("extendfile: pcbmap"); 1072 else 1073 bp->b_blkno = blkno; 1074 } 1075 vfs_bio_clrbuf(bp); 1076 if (bpp) { 1077 *bpp = bp; 1078 bpp = NULL; 1079 } else 1080 bdwrite(bp); 1081 } 1082 } 1083 } 1084 1085 return (0); 1086 } 1087 1088 /*- 1089 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1090 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1091 * this bit is not defined for FAT12 volumes, which are always assumed to 1092 * be clean. 1093 * 1094 * The fatentry() routine only works on cluster numbers that a file could 1095 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1096 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1097 * 1098 * Inputs: 1099 * pmp The MS-DOS volume to mark 1100 * dirty Non-zero if the volume should be marked dirty; zero if it 1101 * should be marked clean 1102 * 1103 * Result: 1104 * 0 Success 1105 * EROFS Volume is read-only 1106 * ? (other errors from called routines) 1107 */ 1108 int 1109 markvoldirty(struct msdosfsmount *pmp, int dirty) 1110 { 1111 struct buf *bp; 1112 u_long bn, bo, bsize, byteoffset, fatval; 1113 int error; 1114 1115 /* 1116 * FAT12 does not support a "clean" bit, so don't do anything for 1117 * FAT12. 1118 */ 1119 if (FAT12(pmp)) 1120 return (0); 1121 1122 /* Can't change the bit on a read-only filesystem. */ 1123 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1124 return (EROFS); 1125 1126 /* 1127 * Fetch the block containing the FAT entry. It is given by the 1128 * pseudo-cluster 1. 1129 */ 1130 byteoffset = FATOFS(pmp, 1); 1131 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1132 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1133 if (error) { 1134 brelse(bp); 1135 return (error); 1136 } 1137 1138 /* 1139 * Get the current value of the FAT entry and set/clear the relevant 1140 * bit. Dirty means clear the "clean" bit; clean means set the 1141 * "clean" bit. 1142 */ 1143 if (FAT32(pmp)) { 1144 /* FAT32 uses bit 27. */ 1145 fatval = getulong(&bp->b_data[bo]); 1146 if (dirty) 1147 fatval &= 0xF7FFFFFF; 1148 else 1149 fatval |= 0x08000000; 1150 putulong(&bp->b_data[bo], fatval); 1151 } else { 1152 /* Must be FAT16; use bit 15. */ 1153 fatval = getushort(&bp->b_data[bo]); 1154 if (dirty) 1155 fatval &= 0x7FFF; 1156 else 1157 fatval |= 0x8000; 1158 putushort(&bp->b_data[bo], fatval); 1159 } 1160 1161 /* Write out the modified FAT block synchronously. */ 1162 return (bwrite(bp)); 1163 } 1164