Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
FreeBSD/Linux Kernel Cross Reference
sys/fs/msdosfs/msdosfs_fat.c
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
SearchContext: - none - 3 - 10
1 /* $FreeBSD: releng/12.0/sys/fs/msdosfs/msdosfs_fat.c 337456 2018-08-08 15:08:22Z pfg $ */ 2 /* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 ws Exp $ */ 3 4 /*- 5 * SPDX-License-Identifier: BSD-4-Clause 6 * 7 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank. 8 * Copyright (C) 1994, 1995, 1997 TooLs GmbH. 9 * All rights reserved. 10 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below). 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by TooLs GmbH. 23 * 4. The name of TooLs GmbH may not be used to endorse or promote products 24 * derived from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 31 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 32 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 33 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 34 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 35 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 /*- 38 * Written by Paul Popelka (paulp@uts.amdahl.com) 39 * 40 * You can do anything you want with this software, just don't say you wrote 41 * it, and don't remove this notice. 42 * 43 * This software is provided "as is". 44 * 45 * The author supplies this software to be publicly redistributed on the 46 * understanding that the author is not responsible for the correct 47 * functioning of this software in any circumstances and is not liable for 48 * any damages caused by this software. 49 * 50 * October 1992 51 */ 52 53 #include <sys/param.h> 54 #include <sys/systm.h> 55 #include <sys/buf.h> 56 #include <sys/mount.h> 57 #include <sys/vnode.h> 58 59 #include <fs/msdosfs/bpb.h> 60 #include <fs/msdosfs/direntry.h> 61 #include <fs/msdosfs/denode.h> 62 #include <fs/msdosfs/fat.h> 63 #include <fs/msdosfs/msdosfsmount.h> 64 65 #define FULL_RUN ((u_int)0xffffffff) 66 67 static int chainalloc(struct msdosfsmount *pmp, u_long start, 68 u_long count, u_long fillwith, u_long *retcluster, 69 u_long *got); 70 static int chainlength(struct msdosfsmount *pmp, u_long start, 71 u_long count); 72 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 73 u_long *sizep, u_long *bop); 74 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 75 u_long fillwith); 76 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 77 u_long *fsrcnp); 78 static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 79 u_long fatbn); 80 static __inline void 81 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 82 static __inline void 83 usemap_free(struct msdosfsmount *pmp, u_long cn); 84 static int clusteralloc1(struct msdosfsmount *pmp, u_long start, 85 u_long count, u_long fillwith, u_long *retcluster, 86 u_long *got); 87 88 static void 89 fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 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 * sp - pointer to returned block size 119 * 120 * NOTE: Either bnp or cnp must be non-null. 121 * This function has one side effect. If the requested file relative cluster 122 * is beyond the end of file, then the actual number of clusters in the file 123 * is returned in *cnp. This is useful for determining how long a directory is. 124 * If cnp is null, nothing is returned. 125 */ 126 int 127 pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp) 128 { 129 int error; 130 u_long i; 131 u_long cn; 132 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 133 u_long byteoffset; 134 u_long bn; 135 u_long bo; 136 struct buf *bp = NULL; 137 u_long bp_bn = -1; 138 struct msdosfsmount *pmp = dep->de_pmp; 139 u_long bsize; 140 141 KASSERT(bnp != NULL || cnp != NULL || sp != NULL, 142 ("pcbmap: extra call")); 143 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap"); 144 145 cn = dep->de_StartCluster; 146 /* 147 * The "file" that makes up the root directory is contiguous, 148 * permanently allocated, of fixed size, and is not made up of 149 * clusters. If the cluster number is beyond the end of the root 150 * directory, then return the number of clusters in the file. 151 */ 152 if (cn == MSDOSFSROOT) { 153 if (dep->de_Attributes & ATTR_DIRECTORY) { 154 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 155 if (cnp) 156 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 157 return (E2BIG); 158 } 159 if (bnp) 160 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 161 if (cnp) 162 *cnp = MSDOSFSROOT; 163 if (sp) 164 *sp = min(pmp->pm_bpcluster, 165 dep->de_FileSize - de_cn2off(pmp, findcn)); 166 return (0); 167 } else { /* just an empty file */ 168 if (cnp) 169 *cnp = 0; 170 return (E2BIG); 171 } 172 } 173 174 /* 175 * All other files do I/O in cluster sized blocks 176 */ 177 if (sp) 178 *sp = pmp->pm_bpcluster; 179 180 /* 181 * Rummage around in the FAT cache, maybe we can avoid tromping 182 * through every FAT entry for the file. And, keep track of how far 183 * off the cache was from where we wanted to be. 184 */ 185 i = 0; 186 fc_lookup(dep, findcn, &i, &cn); 187 188 /* 189 * Handle all other files or directories the normal way. 190 */ 191 for (; i < findcn; i++) { 192 /* 193 * Stop with all reserved clusters, not just with EOF. 194 */ 195 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 196 goto hiteof; 197 byteoffset = FATOFS(pmp, cn); 198 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 199 if (bn != bp_bn) { 200 if (bp) 201 brelse(bp); 202 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 203 if (error) { 204 brelse(bp); 205 return (error); 206 } 207 bp_bn = bn; 208 } 209 prevcn = cn; 210 if (bo >= bsize) { 211 if (bp) 212 brelse(bp); 213 return (EIO); 214 } 215 if (FAT32(pmp)) 216 cn = getulong(&bp->b_data[bo]); 217 else 218 cn = getushort(&bp->b_data[bo]); 219 if (FAT12(pmp) && (prevcn & 1)) 220 cn >>= 4; 221 cn &= pmp->pm_fatmask; 222 223 /* 224 * Force the special cluster numbers 225 * to be the same for all cluster sizes 226 * to let the rest of msdosfs handle 227 * all cases the same. 228 */ 229 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 230 cn |= ~pmp->pm_fatmask; 231 } 232 233 if (!MSDOSFSEOF(pmp, cn)) { 234 if (bp) 235 brelse(bp); 236 if (bnp) 237 *bnp = cntobn(pmp, cn); 238 if (cnp) 239 *cnp = cn; 240 fc_setcache(dep, FC_LASTMAP, i, cn); 241 return (0); 242 } 243 244 hiteof:; 245 if (cnp) 246 *cnp = i; 247 if (bp) 248 brelse(bp); 249 /* update last file cluster entry in the FAT cache */ 250 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 251 return (E2BIG); 252 } 253 254 /* 255 * Find the closest entry in the FAT cache to the cluster we are looking 256 * for. 257 */ 258 static void 259 fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp) 260 { 261 int i; 262 u_long cn; 263 struct fatcache *closest = NULL; 264 265 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup"); 266 267 for (i = 0; i < FC_SIZE; i++) { 268 cn = dep->de_fc[i].fc_frcn; 269 if (cn != FCE_EMPTY && cn <= findcn) { 270 if (closest == NULL || cn > closest->fc_frcn) 271 closest = &dep->de_fc[i]; 272 } 273 } 274 if (closest) { 275 *frcnp = closest->fc_frcn; 276 *fsrcnp = closest->fc_fsrcn; 277 } 278 } 279 280 /* 281 * Purge the FAT cache in denode dep of all entries relating to file 282 * relative cluster frcn and beyond. 283 */ 284 void 285 fc_purge(struct denode *dep, u_int frcn) 286 { 287 int i; 288 struct fatcache *fcp; 289 290 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge"); 291 292 fcp = dep->de_fc; 293 for (i = 0; i < FC_SIZE; i++, fcp++) { 294 if (fcp->fc_frcn >= frcn) 295 fcp->fc_frcn = FCE_EMPTY; 296 } 297 } 298 299 /* 300 * Update the FAT. 301 * If mirroring the FAT, update all copies, with the first copy as last. 302 * Else update only the current FAT (ignoring the others). 303 * 304 * pmp - msdosfsmount structure for filesystem to update 305 * bp - addr of modified FAT block 306 * fatbn - block number relative to begin of filesystem of the modified FAT block. 307 */ 308 static void 309 updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn) 310 { 311 struct buf *bpn; 312 int cleanfat, i; 313 314 #ifdef MSDOSFS_DEBUG 315 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 316 #endif 317 318 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 319 /* 320 * Now copy the block(s) of the modified FAT to the other copies of 321 * the FAT and write them out. This is faster than reading in the 322 * other FATs and then writing them back out. This could tie up 323 * the FAT for quite a while. Preventing others from accessing it. 324 * To prevent us from going after the FAT quite so much we use 325 * delayed writes, unless they specified "synchronous" when the 326 * filesystem was mounted. If synch is asked for then use 327 * bwrite()'s and really slow things down. 328 */ 329 if (fatbn != pmp->pm_fatblk || FAT12(pmp)) 330 cleanfat = 0; 331 else if (FAT16(pmp)) 332 cleanfat = 16; 333 else 334 cleanfat = 32; 335 for (i = 1; i < pmp->pm_FATs; i++) { 336 fatbn += pmp->pm_FATsecs; 337 /* getblk() never fails */ 338 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 339 0, 0, 0); 340 memcpy(bpn->b_data, bp->b_data, bp->b_bcount); 341 /* Force the clean bit on in the other copies. */ 342 if (cleanfat == 16) 343 ((uint8_t *)bpn->b_data)[3] |= 0x80; 344 else if (cleanfat == 32) 345 ((uint8_t *)bpn->b_data)[7] |= 0x08; 346 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 347 bwrite(bpn); 348 else 349 bdwrite(bpn); 350 } 351 } 352 353 /* 354 * Write out the first (or current) FAT last. 355 */ 356 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 357 bwrite(bp); 358 else 359 bdwrite(bp); 360 } 361 362 /* 363 * Updating entries in 12 bit FATs is a pain in the butt. 364 * 365 * The following picture shows where nibbles go when moving from a 12 bit 366 * cluster number into the appropriate bytes in the FAT. 367 * 368 * byte m byte m+1 byte m+2 369 * +----+----+ +----+----+ +----+----+ 370 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 371 * +----+----+ +----+----+ +----+----+ 372 * 373 * +----+----+----+ +----+----+----+ 374 * | 3 0 1 | | 4 5 2 | 375 * +----+----+----+ +----+----+----+ 376 * cluster n cluster n+1 377 * 378 * Where n is even. m = n + (n >> 2) 379 * 380 */ 381 static __inline void 382 usemap_alloc(struct msdosfsmount *pmp, u_long cn) 383 { 384 385 MSDOSFS_ASSERT_MP_LOCKED(pmp); 386 387 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 388 pmp->pm_maxcluster)); 389 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 390 ("usemap_alloc on ro msdosfs mount")); 391 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 392 == 0, ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS, 393 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 394 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 395 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little")); 396 pmp->pm_freeclustercount--; 397 pmp->pm_flags |= MSDOSFS_FSIMOD; 398 } 399 400 static __inline void 401 usemap_free(struct msdosfsmount *pmp, u_long cn) 402 { 403 404 MSDOSFS_ASSERT_MP_LOCKED(pmp); 405 406 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 407 pmp->pm_maxcluster)); 408 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 409 ("usemap_free on ro msdosfs mount")); 410 pmp->pm_freeclustercount++; 411 pmp->pm_flags |= MSDOSFS_FSIMOD; 412 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 413 != 0, ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS, 414 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 415 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1U << (cn % N_INUSEBITS)); 416 } 417 418 int 419 clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp) 420 { 421 int error; 422 u_long oldcn; 423 424 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 425 if (error) 426 return (error); 427 /* 428 * If the cluster was successfully marked free, then update 429 * the count of free clusters, and turn off the "allocated" 430 * bit in the "in use" cluster bit map. 431 */ 432 MSDOSFS_LOCK_MP(pmp); 433 usemap_free(pmp, cluster); 434 MSDOSFS_UNLOCK_MP(pmp); 435 if (oldcnp) 436 *oldcnp = oldcn; 437 return (0); 438 } 439 440 /* 441 * Get or Set or 'Get and Set' the cluster'th entry in the FAT. 442 * 443 * function - whether to get or set a FAT entry 444 * pmp - address of the msdosfsmount structure for the filesystem 445 * whose FAT is to be manipulated. 446 * cn - which cluster is of interest 447 * oldcontents - address of a word that is to receive the contents of the 448 * cluster'th entry if this is a get function 449 * newcontents - the new value to be written into the cluster'th element of 450 * the FAT if this is a set function. 451 * 452 * This function can also be used to free a cluster by setting the FAT entry 453 * for a cluster to 0. 454 * 455 * All copies of the FAT are updated if this is a set function. NOTE: If 456 * fatentry() marks a cluster as free it does not update the inusemap in 457 * the msdosfsmount structure. This is left to the caller. 458 */ 459 int 460 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, 461 u_long newcontents) 462 { 463 int error; 464 u_long readcn; 465 u_long bn, bo, bsize, byteoffset; 466 struct buf *bp; 467 468 #ifdef MSDOSFS_DEBUG 469 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 470 function, pmp, cn, oldcontents, newcontents); 471 #endif 472 473 #ifdef DIAGNOSTIC 474 /* 475 * Be sure they asked us to do something. 476 */ 477 if ((function & (FAT_SET | FAT_GET)) == 0) { 478 #ifdef MSDOSFS_DEBUG 479 printf("fatentry(): function code doesn't specify get or set\n"); 480 #endif 481 return (EINVAL); 482 } 483 484 /* 485 * If they asked us to return a cluster number but didn't tell us 486 * where to put it, give them an error. 487 */ 488 if ((function & FAT_GET) && oldcontents == NULL) { 489 #ifdef MSDOSFS_DEBUG 490 printf("fatentry(): get function with no place to put result\n"); 491 #endif 492 return (EINVAL); 493 } 494 #endif 495 496 /* 497 * Be sure the requested cluster is in the filesystem. 498 */ 499 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 500 return (EINVAL); 501 502 byteoffset = FATOFS(pmp, cn); 503 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 504 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 505 if (error) { 506 brelse(bp); 507 return (error); 508 } 509 510 if (function & FAT_GET) { 511 if (FAT32(pmp)) 512 readcn = getulong(&bp->b_data[bo]); 513 else 514 readcn = getushort(&bp->b_data[bo]); 515 if (FAT12(pmp) & (cn & 1)) 516 readcn >>= 4; 517 readcn &= pmp->pm_fatmask; 518 /* map reserved FAT entries to same values for all FATs */ 519 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 520 readcn |= ~pmp->pm_fatmask; 521 *oldcontents = readcn; 522 } 523 if (function & FAT_SET) { 524 switch (pmp->pm_fatmask) { 525 case FAT12_MASK: 526 readcn = getushort(&bp->b_data[bo]); 527 if (cn & 1) { 528 readcn &= 0x000f; 529 readcn |= newcontents << 4; 530 } else { 531 readcn &= 0xf000; 532 readcn |= newcontents & 0xfff; 533 } 534 putushort(&bp->b_data[bo], readcn); 535 break; 536 case FAT16_MASK: 537 putushort(&bp->b_data[bo], newcontents); 538 break; 539 case FAT32_MASK: 540 /* 541 * According to spec we have to retain the 542 * high order bits of the FAT entry. 543 */ 544 readcn = getulong(&bp->b_data[bo]); 545 readcn &= ~FAT32_MASK; 546 readcn |= newcontents & FAT32_MASK; 547 putulong(&bp->b_data[bo], readcn); 548 break; 549 } 550 updatefats(pmp, bp, bn); 551 bp = NULL; 552 pmp->pm_fmod = 1; 553 } 554 if (bp) 555 brelse(bp); 556 return (0); 557 } 558 559 /* 560 * Update a contiguous cluster chain 561 * 562 * pmp - mount point 563 * start - first cluster of chain 564 * count - number of clusters in chain 565 * fillwith - what to write into FAT entry of last cluster 566 */ 567 static int 568 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) 569 { 570 int error; 571 u_long bn, bo, bsize, byteoffset, readcn, newc; 572 struct buf *bp; 573 574 #ifdef MSDOSFS_DEBUG 575 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 576 pmp, start, count, fillwith); 577 #endif 578 /* 579 * Be sure the clusters are in the filesystem. 580 */ 581 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 582 return (EINVAL); 583 584 while (count > 0) { 585 byteoffset = FATOFS(pmp, start); 586 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 587 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 588 if (error) { 589 brelse(bp); 590 return (error); 591 } 592 while (count > 0) { 593 start++; 594 newc = --count > 0 ? start : fillwith; 595 switch (pmp->pm_fatmask) { 596 case FAT12_MASK: 597 readcn = getushort(&bp->b_data[bo]); 598 if (start & 1) { 599 readcn &= 0xf000; 600 readcn |= newc & 0xfff; 601 } else { 602 readcn &= 0x000f; 603 readcn |= newc << 4; 604 } 605 putushort(&bp->b_data[bo], readcn); 606 bo++; 607 if (!(start & 1)) 608 bo++; 609 break; 610 case FAT16_MASK: 611 putushort(&bp->b_data[bo], newc); 612 bo += 2; 613 break; 614 case FAT32_MASK: 615 readcn = getulong(&bp->b_data[bo]); 616 readcn &= ~pmp->pm_fatmask; 617 readcn |= newc & pmp->pm_fatmask; 618 putulong(&bp->b_data[bo], readcn); 619 bo += 4; 620 break; 621 } 622 if (bo >= bsize) 623 break; 624 } 625 updatefats(pmp, bp, bn); 626 } 627 pmp->pm_fmod = 1; 628 return (0); 629 } 630 631 /* 632 * Check the length of a free cluster chain starting at start. 633 * 634 * pmp - mount point 635 * start - start of chain 636 * count - maximum interesting length 637 */ 638 static int 639 chainlength(struct msdosfsmount *pmp, u_long start, u_long count) 640 { 641 u_long idx, max_idx; 642 u_int map; 643 u_long len; 644 645 MSDOSFS_ASSERT_MP_LOCKED(pmp); 646 647 if (start > pmp->pm_maxcluster) 648 return (0); 649 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 650 idx = start / N_INUSEBITS; 651 start %= N_INUSEBITS; 652 map = pmp->pm_inusemap[idx]; 653 map &= ~((1 << start) - 1); 654 if (map) { 655 len = ffs(map) - 1 - start; 656 len = MIN(len, count); 657 if (start + len > pmp->pm_maxcluster) 658 len = pmp->pm_maxcluster - start + 1; 659 return (len); 660 } 661 len = N_INUSEBITS - start; 662 if (len >= count) { 663 len = count; 664 if (start + len > pmp->pm_maxcluster) 665 len = pmp->pm_maxcluster - start + 1; 666 return (len); 667 } 668 while (++idx <= max_idx) { 669 if (len >= count) 670 break; 671 map = pmp->pm_inusemap[idx]; 672 if (map) { 673 len += ffs(map) - 1; 674 break; 675 } 676 len += N_INUSEBITS; 677 } 678 len = MIN(len, count); 679 if (start + len > pmp->pm_maxcluster) 680 len = pmp->pm_maxcluster - start + 1; 681 return (len); 682 } 683 684 /* 685 * Allocate contigous free clusters. 686 * 687 * pmp - mount point. 688 * start - start of cluster chain. 689 * count - number of clusters to allocate. 690 * fillwith - put this value into the FAT entry for the 691 * last allocated cluster. 692 * retcluster - put the first allocated cluster's number here. 693 * got - how many clusters were actually allocated. 694 */ 695 static int 696 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, 697 u_long fillwith, u_long *retcluster, u_long *got) 698 { 699 int error; 700 u_long cl, n; 701 702 MSDOSFS_ASSERT_MP_LOCKED(pmp); 703 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 704 ("chainalloc on ro msdosfs mount")); 705 706 for (cl = start, n = count; n-- > 0;) 707 usemap_alloc(pmp, cl++); 708 pmp->pm_nxtfree = start + count; 709 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 710 pmp->pm_nxtfree = CLUST_FIRST; 711 pmp->pm_flags |= MSDOSFS_FSIMOD; 712 error = fatchain(pmp, start, count, fillwith); 713 if (error != 0) { 714 for (cl = start, n = count; n-- > 0;) 715 usemap_free(pmp, cl++); 716 return (error); 717 } 718 #ifdef MSDOSFS_DEBUG 719 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 720 start, count); 721 #endif 722 if (retcluster) 723 *retcluster = start; 724 if (got) 725 *got = count; 726 return (0); 727 } 728 729 /* 730 * Allocate contiguous free clusters. 731 * 732 * pmp - mount point. 733 * start - preferred start of cluster chain. 734 * count - number of clusters requested. 735 * fillwith - put this value into the FAT entry for the 736 * last allocated cluster. 737 * retcluster - put the first allocated cluster's number here. 738 * got - how many clusters were actually allocated. 739 */ 740 int 741 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 742 u_long fillwith, u_long *retcluster, u_long *got) 743 { 744 int error; 745 746 MSDOSFS_LOCK_MP(pmp); 747 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 748 MSDOSFS_UNLOCK_MP(pmp); 749 return (error); 750 } 751 752 static int 753 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 754 u_long fillwith, u_long *retcluster, u_long *got) 755 { 756 u_long idx; 757 u_long len, newst, foundl, cn, l; 758 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 759 u_int map; 760 761 MSDOSFS_ASSERT_MP_LOCKED(pmp); 762 763 #ifdef MSDOSFS_DEBUG 764 printf("clusteralloc(): find %lu clusters\n", count); 765 #endif 766 if (start) { 767 if ((len = chainlength(pmp, start, count)) >= count) 768 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 769 } else 770 len = 0; 771 772 newst = pmp->pm_nxtfree; 773 foundl = 0; 774 775 for (cn = newst; cn <= pmp->pm_maxcluster;) { 776 idx = cn / N_INUSEBITS; 777 map = pmp->pm_inusemap[idx]; 778 map |= (1U << (cn % N_INUSEBITS)) - 1; 779 if (map != FULL_RUN) { 780 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 781 if ((l = chainlength(pmp, cn, count)) >= count) 782 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 783 if (l > foundl) { 784 foundcn = cn; 785 foundl = l; 786 } 787 cn += l + 1; 788 continue; 789 } 790 cn += N_INUSEBITS - cn % N_INUSEBITS; 791 } 792 for (cn = 0; cn < newst;) { 793 idx = cn / N_INUSEBITS; 794 map = pmp->pm_inusemap[idx]; 795 map |= (1U << (cn % N_INUSEBITS)) - 1; 796 if (map != FULL_RUN) { 797 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 798 if ((l = chainlength(pmp, cn, count)) >= count) 799 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 800 if (l > foundl) { 801 foundcn = cn; 802 foundl = l; 803 } 804 cn += l + 1; 805 continue; 806 } 807 cn += N_INUSEBITS - cn % N_INUSEBITS; 808 } 809 810 if (!foundl) 811 return (ENOSPC); 812 813 if (len) 814 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 815 else 816 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 817 } 818 819 820 /* 821 * Free a chain of clusters. 822 * 823 * pmp - address of the msdosfs mount structure for the filesystem 824 * containing the cluster chain to be freed. 825 * startcluster - number of the 1st cluster in the chain of clusters to be 826 * freed. 827 */ 828 int 829 freeclusterchain(struct msdosfsmount *pmp, u_long cluster) 830 { 831 int error; 832 struct buf *bp = NULL; 833 u_long bn, bo, bsize, byteoffset; 834 u_long readcn, lbn = -1; 835 836 MSDOSFS_LOCK_MP(pmp); 837 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 838 byteoffset = FATOFS(pmp, cluster); 839 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 840 if (lbn != bn) { 841 if (bp) 842 updatefats(pmp, bp, lbn); 843 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 844 if (error) { 845 brelse(bp); 846 MSDOSFS_UNLOCK_MP(pmp); 847 return (error); 848 } 849 lbn = bn; 850 } 851 usemap_free(pmp, cluster); 852 switch (pmp->pm_fatmask) { 853 case FAT12_MASK: 854 readcn = getushort(&bp->b_data[bo]); 855 if (cluster & 1) { 856 cluster = readcn >> 4; 857 readcn &= 0x000f; 858 readcn |= MSDOSFSFREE << 4; 859 } else { 860 cluster = readcn; 861 readcn &= 0xf000; 862 readcn |= MSDOSFSFREE & 0xfff; 863 } 864 putushort(&bp->b_data[bo], readcn); 865 break; 866 case FAT16_MASK: 867 cluster = getushort(&bp->b_data[bo]); 868 putushort(&bp->b_data[bo], MSDOSFSFREE); 869 break; 870 case FAT32_MASK: 871 cluster = getulong(&bp->b_data[bo]); 872 putulong(&bp->b_data[bo], 873 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 874 break; 875 } 876 cluster &= pmp->pm_fatmask; 877 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 878 cluster |= pmp->pm_fatmask; 879 } 880 if (bp) 881 updatefats(pmp, bp, bn); 882 MSDOSFS_UNLOCK_MP(pmp); 883 return (0); 884 } 885 886 /* 887 * Read in FAT blocks looking for free clusters. For every free cluster 888 * found turn off its corresponding bit in the pm_inusemap. 889 */ 890 int 891 fillinusemap(struct msdosfsmount *pmp) 892 { 893 struct buf *bp; 894 u_long bn, bo, bsize, byteoffset, cn, readcn; 895 int error; 896 897 MSDOSFS_ASSERT_MP_LOCKED(pmp); 898 bp = NULL; 899 900 /* 901 * Mark all clusters in use, we mark the free ones in the FAT scan 902 * loop further down. 903 */ 904 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 905 pmp->pm_inusemap[cn] = FULL_RUN; 906 907 /* 908 * Figure how many free clusters are in the filesystem by ripping 909 * through the FAT counting the number of entries whose content is 910 * zero. These represent free clusters. 911 */ 912 pmp->pm_freeclustercount = 0; 913 for (cn = 0; cn <= pmp->pm_maxcluster; cn++) { 914 byteoffset = FATOFS(pmp, cn); 915 bo = byteoffset % pmp->pm_fatblocksize; 916 if (bo == 0) { 917 /* Read new FAT block */ 918 if (bp != NULL) 919 brelse(bp); 920 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 921 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 922 if (error != 0) 923 return (error); 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 /* 934 * Check if the FAT ID matches the BPB's media descriptor and 935 * all other bits are set to 1. 936 */ 937 if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) | 938 pmp->pm_bpb.bpbMedia)) { 939 #ifdef MSDOSFS_DEBUG 940 printf("mountmsdosfs(): Media descriptor in BPB" 941 "does not match FAT ID\n"); 942 #endif 943 brelse(bp); 944 return (EINVAL); 945 } else if (readcn == CLUST_FREE) 946 usemap_free(pmp, cn); 947 } 948 if (bp != NULL) 949 brelse(bp); 950 951 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster + 952 N_INUSEBITS) / N_INUSEBITS; cn++) 953 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 954 955 return (0); 956 } 957 958 /* 959 * Allocate a new cluster and chain it onto the end of the file. 960 * 961 * dep - the file to extend 962 * count - number of clusters to allocate 963 * bpp - where to return the address of the buf header for the first new 964 * file block 965 * ncp - where to put cluster number of the first newly allocated cluster 966 * If this pointer is 0, do not return the cluster number. 967 * flags - see fat.h 968 * 969 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 970 * the de_flag field of the denode and it does not change the de_FileSize 971 * field. This is left for the caller to do. 972 */ 973 int 974 extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp, 975 int flags) 976 { 977 int error; 978 u_long frcn; 979 u_long cn, got; 980 struct msdosfsmount *pmp = dep->de_pmp; 981 struct buf *bp; 982 daddr_t blkno; 983 984 /* 985 * Don't try to extend the root directory 986 */ 987 if (dep->de_StartCluster == MSDOSFSROOT 988 && (dep->de_Attributes & ATTR_DIRECTORY)) { 989 #ifdef MSDOSFS_DEBUG 990 printf("extendfile(): attempt to extend root directory\n"); 991 #endif 992 return (ENOSPC); 993 } 994 995 /* 996 * If the "file's last cluster" cache entry is empty, and the file 997 * is not empty, then fill the cache entry by calling pcbmap(). 998 */ 999 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 1000 dep->de_StartCluster != 0) { 1001 error = pcbmap(dep, 0xffff, 0, &cn, 0); 1002 /* we expect it to return E2BIG */ 1003 if (error != E2BIG) 1004 return (error); 1005 } 1006 1007 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 1008 dep->de_fc[FC_LASTFC].fc_frcn; 1009 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 1010 dep->de_fc[FC_LASTFC].fc_fsrcn; 1011 while (count > 0) { 1012 /* 1013 * Allocate a new cluster chain and cat onto the end of the 1014 * file. If the file is empty we make de_StartCluster point 1015 * to the new block. Note that de_StartCluster being 0 is 1016 * sufficient to be sure the file is empty since we exclude 1017 * attempts to extend the root directory above, and the root 1018 * dir is the only file with a startcluster of 0 that has 1019 * blocks allocated (sort of). 1020 */ 1021 if (dep->de_StartCluster == 0) 1022 cn = 0; 1023 else 1024 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1025 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1026 if (error) 1027 return (error); 1028 1029 count -= got; 1030 1031 /* 1032 * Give them the filesystem relative cluster number if they want 1033 * it. 1034 */ 1035 if (ncp) { 1036 *ncp = cn; 1037 ncp = NULL; 1038 } 1039 1040 if (dep->de_StartCluster == 0) { 1041 dep->de_StartCluster = cn; 1042 frcn = 0; 1043 } else { 1044 error = fatentry(FAT_SET, pmp, 1045 dep->de_fc[FC_LASTFC].fc_fsrcn, 1046 0, cn); 1047 if (error) { 1048 clusterfree(pmp, cn, NULL); 1049 return (error); 1050 } 1051 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1052 } 1053 1054 /* 1055 * Update the "last cluster of the file" entry in the 1056 * denode's FAT cache. 1057 */ 1058 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1059 1060 if (flags & DE_CLEAR) { 1061 while (got-- > 0) { 1062 /* 1063 * Get the buf header for the new block of the file. 1064 */ 1065 if (dep->de_Attributes & ATTR_DIRECTORY) 1066 bp = getblk(pmp->pm_devvp, 1067 cntobn(pmp, cn++), 1068 pmp->pm_bpcluster, 0, 0, 0); 1069 else { 1070 bp = getblk(DETOV(dep), 1071 frcn++, 1072 pmp->pm_bpcluster, 0, 0, 0); 1073 /* 1074 * Do the bmap now, as in msdosfs_write 1075 */ 1076 if (pcbmap(dep, 1077 bp->b_lblkno, 1078 &blkno, 0, 0)) 1079 bp->b_blkno = -1; 1080 if (bp->b_blkno == -1) 1081 panic("extendfile: pcbmap"); 1082 else 1083 bp->b_blkno = blkno; 1084 } 1085 clrbuf(bp); 1086 if (bpp) { 1087 *bpp = bp; 1088 bpp = NULL; 1089 } else 1090 bdwrite(bp); 1091 } 1092 } 1093 } 1094 1095 return (0); 1096 } 1097 1098 /*- 1099 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1100 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1101 * this bit is not defined for FAT12 volumes, which are always assumed to 1102 * be clean. 1103 * 1104 * The fatentry() routine only works on cluster numbers that a file could 1105 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1106 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1107 * 1108 * Inputs: 1109 * pmp The MS-DOS volume to mark 1110 * dirty Non-zero if the volume should be marked dirty; zero if it 1111 * should be marked clean 1112 * 1113 * Result: 1114 * 0 Success 1115 * EROFS Volume is read-only 1116 * ? (other errors from called routines) 1117 */ 1118 int 1119 markvoldirty(struct msdosfsmount *pmp, int dirty) 1120 { 1121 struct buf *bp; 1122 u_long bn, bo, bsize, byteoffset, fatval; 1123 int error; 1124 1125 /* 1126 * FAT12 does not support a "clean" bit, so don't do anything for 1127 * FAT12. 1128 */ 1129 if (FAT12(pmp)) 1130 return (0); 1131 1132 /* Can't change the bit on a read-only filesystem. */ 1133 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1134 return (EROFS); 1135 1136 /* 1137 * Fetch the block containing the FAT entry. It is given by the 1138 * pseudo-cluster 1. 1139 */ 1140 byteoffset = FATOFS(pmp, 1); 1141 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1142 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1143 if (error) { 1144 brelse(bp); 1145 return (error); 1146 } 1147 1148 /* 1149 * Get the current value of the FAT entry and set/clear the relevant 1150 * bit. Dirty means clear the "clean" bit; clean means set the 1151 * "clean" bit. 1152 */ 1153 if (FAT32(pmp)) { 1154 /* FAT32 uses bit 27. */ 1155 fatval = getulong(&bp->b_data[bo]); 1156 if (dirty) 1157 fatval &= 0xF7FFFFFF; 1158 else 1159 fatval |= 0x08000000; 1160 putulong(&bp->b_data[bo], fatval); 1161 } else { 1162 /* Must be FAT16; use bit 15. */ 1163 fatval = getushort(&bp->b_data[bo]); 1164 if (dirty) 1165 fatval &= 0x7FFF; 1166 else 1167 fatval |= 0x8000; 1168 putushort(&bp->b_data[bo], fatval); 1169 } 1170 1171 /* Write out the modified FAT block synchronously. */ 1172 return (bwrite(bp)); 1173 }
Cache object: 09f858920e95961f1cd62fe700aa31d0
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]