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 /* $FreeBSD$ */ 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/vmmeter.h> 58 #include <sys/vnode.h> 59 60 #include <fs/msdosfs/bpb.h> 61 #include <fs/msdosfs/direntry.h> 62 #include <fs/msdosfs/denode.h> 63 #include <fs/msdosfs/fat.h> 64 #include <fs/msdosfs/msdosfsmount.h> 65 66 #define FULL_RUN ((u_int)0xffffffff) 67 68 static int chainalloc(struct msdosfsmount *pmp, u_long start, 69 u_long count, u_long fillwith, u_long *retcluster, 70 u_long *got); 71 static int chainlength(struct msdosfsmount *pmp, u_long start, 72 u_long count); 73 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 74 u_long *sizep, u_long *bop); 75 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 76 u_long fillwith); 77 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 78 u_long *fsrcnp); 79 static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 80 u_long fatbn); 81 static __inline void 82 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 83 static __inline void 84 usemap_free(struct msdosfsmount *pmp, u_long cn); 85 static int clusteralloc1(struct msdosfsmount *pmp, u_long start, 86 u_long count, u_long fillwith, u_long *retcluster, 87 u_long *got); 88 89 static void 90 fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep, 91 u_long *bop) 92 { 93 u_long bn, size; 94 95 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 96 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 97 * DEV_BSIZE; 98 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 99 100 if (bnp) 101 *bnp = bn; 102 if (sizep) 103 *sizep = size; 104 if (bop) 105 *bop = ofs % pmp->pm_fatblocksize; 106 } 107 108 /* 109 * Map the logical cluster number of a file into a physical disk sector 110 * that is filesystem relative. 111 * 112 * dep - address of denode representing the file of interest 113 * findcn - file relative cluster whose filesystem relative cluster number 114 * and/or block number are/is to be found 115 * bnp - address of where to place the filesystem relative block number. 116 * If this pointer is null then don't return this quantity. 117 * cnp - address of where to place the filesystem relative cluster number. 118 * If this pointer is null then don't return this quantity. 119 * sp - pointer to returned block size 120 * 121 * NOTE: Either bnp or cnp must be non-null. 122 * This function has one side effect. If the requested file relative cluster 123 * is beyond the end of file, then the actual number of clusters in the file 124 * is returned in *cnp. This is useful for determining how long a directory is. 125 * If cnp is null, nothing is returned. 126 */ 127 int 128 pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp) 129 { 130 int error; 131 u_long i; 132 u_long cn; 133 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 134 u_long byteoffset; 135 u_long bn; 136 u_long bo; 137 struct buf *bp = NULL; 138 u_long bp_bn = -1; 139 struct msdosfsmount *pmp = dep->de_pmp; 140 u_long bsize; 141 142 KASSERT(bnp != NULL || cnp != NULL || sp != NULL, 143 ("pcbmap: extra call")); 144 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap"); 145 146 cn = dep->de_StartCluster; 147 /* 148 * The "file" that makes up the root directory is contiguous, 149 * permanently allocated, of fixed size, and is not made up of 150 * clusters. If the cluster number is beyond the end of the root 151 * directory, then return the number of clusters in the file. 152 */ 153 if (cn == MSDOSFSROOT) { 154 if (dep->de_Attributes & ATTR_DIRECTORY) { 155 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 156 if (cnp) 157 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 158 return (E2BIG); 159 } 160 if (bnp) 161 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 162 if (cnp) 163 *cnp = MSDOSFSROOT; 164 if (sp) 165 *sp = min(pmp->pm_bpcluster, 166 dep->de_FileSize - de_cn2off(pmp, findcn)); 167 return (0); 168 } else { /* just an empty file */ 169 if (cnp) 170 *cnp = 0; 171 return (E2BIG); 172 } 173 } 174 175 /* 176 * All other files do I/O in cluster sized blocks 177 */ 178 if (sp) 179 *sp = pmp->pm_bpcluster; 180 181 /* 182 * Rummage around in the FAT cache, maybe we can avoid tromping 183 * through every FAT entry for the file. And, keep track of how far 184 * off the cache was from where we wanted to be. 185 */ 186 i = 0; 187 fc_lookup(dep, findcn, &i, &cn); 188 189 /* 190 * Handle all other files or directories the normal way. 191 */ 192 for (; i < findcn; i++) { 193 /* 194 * Stop with all reserved clusters, not just with EOF. 195 */ 196 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 197 goto hiteof; 198 byteoffset = FATOFS(pmp, cn); 199 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 200 if (bn != bp_bn) { 201 if (bp) 202 brelse(bp); 203 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 204 if (error) { 205 brelse(bp); 206 return (error); 207 } 208 bp_bn = bn; 209 } 210 prevcn = cn; 211 if (bo >= bsize) { 212 if (bp) 213 brelse(bp); 214 return (EIO); 215 } 216 if (FAT32(pmp)) 217 cn = getulong(bp->b_data + bo); 218 else 219 cn = getushort(bp->b_data + bo); 220 if (FAT12(pmp) && (prevcn & 1)) 221 cn >>= 4; 222 cn &= pmp->pm_fatmask; 223 224 /* 225 * Force the special cluster numbers 226 * to be the same for all cluster sizes 227 * to let the rest of msdosfs handle 228 * all cases the same. 229 */ 230 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 231 cn |= ~pmp->pm_fatmask; 232 } 233 234 if (!MSDOSFSEOF(pmp, cn)) { 235 if (bp) 236 brelse(bp); 237 if (bnp) 238 *bnp = cntobn(pmp, cn); 239 if (cnp) 240 *cnp = cn; 241 fc_setcache(dep, FC_LASTMAP, i, cn); 242 return (0); 243 } 244 245 hiteof:; 246 if (cnp) 247 *cnp = i; 248 if (bp) 249 brelse(bp); 250 /* update last file cluster entry in the FAT cache */ 251 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 252 return (E2BIG); 253 } 254 255 /* 256 * Find the closest entry in the FAT cache to the cluster we are looking 257 * for. 258 */ 259 static void 260 fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp) 261 { 262 int i; 263 u_long cn; 264 struct fatcache *closest = NULL; 265 266 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup"); 267 268 for (i = 0; i < FC_SIZE; i++) { 269 cn = dep->de_fc[i].fc_frcn; 270 if (cn != FCE_EMPTY && cn <= findcn) { 271 if (closest == NULL || cn > closest->fc_frcn) 272 closest = &dep->de_fc[i]; 273 } 274 } 275 if (closest) { 276 *frcnp = closest->fc_frcn; 277 *fsrcnp = closest->fc_fsrcn; 278 } 279 } 280 281 /* 282 * Purge the FAT cache in denode dep of all entries relating to file 283 * relative cluster frcn and beyond. 284 */ 285 void 286 fc_purge(struct denode *dep, u_int frcn) 287 { 288 int i; 289 struct fatcache *fcp; 290 291 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge"); 292 293 fcp = dep->de_fc; 294 for (i = 0; i < FC_SIZE; i++, fcp++) { 295 if (fcp->fc_frcn >= frcn) 296 fcp->fc_frcn = FCE_EMPTY; 297 } 298 } 299 300 /* 301 * Update the FAT. 302 * If mirroring the FAT, update all copies, with the first copy as last. 303 * Else update only the current FAT (ignoring the others). 304 * 305 * pmp - msdosfsmount structure for filesystem to update 306 * bp - addr of modified FAT block 307 * fatbn - block number relative to begin of filesystem of the modified FAT block. 308 */ 309 static void 310 updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn) 311 { 312 struct buf *bpn; 313 int cleanfat, i; 314 315 #ifdef MSDOSFS_DEBUG 316 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 317 #endif 318 319 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 320 /* 321 * Now copy the block(s) of the modified FAT to the other copies of 322 * the FAT and write them out. This is faster than reading in the 323 * other FATs and then writing them back out. This could tie up 324 * the FAT for quite a while. Preventing others from accessing it. 325 * To prevent us from going after the FAT quite so much we use 326 * delayed writes, unless they specified "synchronous" when the 327 * filesystem was mounted. If synch is asked for then use 328 * bwrite()'s and really slow things down. 329 */ 330 if (fatbn != pmp->pm_fatblk || FAT12(pmp)) 331 cleanfat = 0; 332 else if (FAT16(pmp)) 333 cleanfat = 16; 334 else 335 cleanfat = 32; 336 for (i = 1; i < pmp->pm_FATs; i++) { 337 fatbn += pmp->pm_FATsecs; 338 /* getblk() never fails */ 339 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 340 0, 0, 0); 341 memcpy(bpn->b_data, bp->b_data, bp->b_bcount); 342 /* Force the clean bit on in the other copies. */ 343 if (cleanfat == 16) 344 ((uint8_t *)bpn->b_data)[3] |= 0x80; 345 else if (cleanfat == 32) 346 ((uint8_t *)bpn->b_data)[7] |= 0x08; 347 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 348 bwrite(bpn); 349 else 350 bdwrite(bpn); 351 } 352 } 353 354 /* 355 * Write out the first (or current) FAT last. 356 */ 357 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 358 bwrite(bp); 359 else 360 bdwrite(bp); 361 } 362 363 /* 364 * Updating entries in 12 bit FATs is a pain in the butt. 365 * 366 * The following picture shows where nibbles go when moving from a 12 bit 367 * cluster number into the appropriate bytes in the FAT. 368 * 369 * byte m byte m+1 byte m+2 370 * +----+----+ +----+----+ +----+----+ 371 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 372 * +----+----+ +----+----+ +----+----+ 373 * 374 * +----+----+----+ +----+----+----+ 375 * | 3 0 1 | | 4 5 2 | 376 * +----+----+----+ +----+----+----+ 377 * cluster n cluster n+1 378 * 379 * Where n is even. m = n + (n >> 2) 380 * 381 */ 382 static __inline void 383 usemap_alloc(struct msdosfsmount *pmp, u_long cn) 384 { 385 386 MSDOSFS_ASSERT_MP_LOCKED(pmp); 387 388 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 389 pmp->pm_maxcluster)); 390 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 391 ("usemap_alloc on ro msdosfs mount")); 392 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & 393 (1U << (cn % N_INUSEBITS))) == 0, 394 ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS, 395 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 396 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 397 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little")); 398 pmp->pm_freeclustercount--; 399 pmp->pm_flags |= MSDOSFS_FSIMOD; 400 } 401 402 static __inline void 403 usemap_free(struct msdosfsmount *pmp, u_long cn) 404 { 405 406 MSDOSFS_ASSERT_MP_LOCKED(pmp); 407 408 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 409 pmp->pm_maxcluster)); 410 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 411 ("usemap_free on ro msdosfs mount")); 412 pmp->pm_freeclustercount++; 413 pmp->pm_flags |= MSDOSFS_FSIMOD; 414 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & 415 (1U << (cn % N_INUSEBITS))) != 0, 416 ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS, 417 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 418 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1U << (cn % N_INUSEBITS)); 419 } 420 421 int 422 clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp) 423 { 424 int error; 425 u_long oldcn; 426 427 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 428 if (error) 429 return (error); 430 /* 431 * If the cluster was successfully marked free, then update 432 * the count of free clusters, and turn off the "allocated" 433 * bit in the "in use" cluster bit map. 434 */ 435 MSDOSFS_LOCK_MP(pmp); 436 usemap_free(pmp, cluster); 437 MSDOSFS_UNLOCK_MP(pmp); 438 if (oldcnp) 439 *oldcnp = oldcn; 440 return (0); 441 } 442 443 /* 444 * Get or Set or 'Get and Set' the cluster'th entry in the FAT. 445 * 446 * function - whether to get or set a FAT entry 447 * pmp - address of the msdosfsmount structure for the filesystem 448 * whose FAT is to be manipulated. 449 * cn - which cluster is of interest 450 * oldcontents - address of a word that is to receive the contents of the 451 * cluster'th entry if this is a get function 452 * newcontents - the new value to be written into the cluster'th element of 453 * the FAT if this is a set function. 454 * 455 * This function can also be used to free a cluster by setting the FAT entry 456 * for a cluster to 0. 457 * 458 * All copies of the FAT are updated if this is a set function. NOTE: If 459 * fatentry() marks a cluster as free it does not update the inusemap in 460 * the msdosfsmount structure. This is left to the caller. 461 */ 462 int 463 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, 464 u_long newcontents) 465 { 466 int error; 467 u_long readcn; 468 u_long bn, bo, bsize, byteoffset; 469 struct buf *bp; 470 471 #ifdef MSDOSFS_DEBUG 472 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 473 function, pmp, cn, oldcontents, newcontents); 474 #endif 475 476 #ifdef DIAGNOSTIC 477 /* 478 * Be sure they asked us to do something. 479 */ 480 if ((function & (FAT_SET | FAT_GET)) == 0) { 481 #ifdef MSDOSFS_DEBUG 482 printf("fatentry(): function code doesn't specify get or set\n"); 483 #endif 484 return (EINVAL); 485 } 486 487 /* 488 * If they asked us to return a cluster number but didn't tell us 489 * where to put it, give them an error. 490 */ 491 if ((function & FAT_GET) && oldcontents == NULL) { 492 #ifdef MSDOSFS_DEBUG 493 printf("fatentry(): get function with no place to put result\n"); 494 #endif 495 return (EINVAL); 496 } 497 #endif 498 499 /* 500 * Be sure the requested cluster is in the filesystem. 501 */ 502 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 503 return (EINVAL); 504 505 byteoffset = FATOFS(pmp, cn); 506 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 507 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 508 if (error) { 509 brelse(bp); 510 return (error); 511 } 512 513 if (function & FAT_GET) { 514 if (FAT32(pmp)) 515 readcn = getulong(bp->b_data + bo); 516 else 517 readcn = getushort(bp->b_data + bo); 518 if (FAT12(pmp) & (cn & 1)) 519 readcn >>= 4; 520 readcn &= pmp->pm_fatmask; 521 /* map reserved FAT entries to same values for all FATs */ 522 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 523 readcn |= ~pmp->pm_fatmask; 524 *oldcontents = readcn; 525 } 526 if (function & FAT_SET) { 527 switch (pmp->pm_fatmask) { 528 case FAT12_MASK: 529 readcn = getushort(bp->b_data + bo); 530 if (cn & 1) { 531 readcn &= 0x000f; 532 readcn |= newcontents << 4; 533 } else { 534 readcn &= 0xf000; 535 readcn |= newcontents & 0xfff; 536 } 537 putushort(bp->b_data + bo, readcn); 538 break; 539 case FAT16_MASK: 540 putushort(bp->b_data + bo, newcontents); 541 break; 542 case FAT32_MASK: 543 /* 544 * According to spec we have to retain the 545 * high order bits of the FAT entry. 546 */ 547 readcn = getulong(bp->b_data + bo); 548 readcn &= ~FAT32_MASK; 549 readcn |= newcontents & FAT32_MASK; 550 putulong(bp->b_data + bo, readcn); 551 break; 552 } 553 updatefats(pmp, bp, bn); 554 bp = NULL; 555 pmp->pm_fmod = 1; 556 } 557 if (bp) 558 brelse(bp); 559 return (0); 560 } 561 562 /* 563 * Update a contiguous cluster chain 564 * 565 * pmp - mount point 566 * start - first cluster of chain 567 * count - number of clusters in chain 568 * fillwith - what to write into FAT entry of last cluster 569 */ 570 static int 571 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) 572 { 573 int error; 574 u_long bn, bo, bsize, byteoffset, readcn, newc; 575 struct buf *bp; 576 577 #ifdef MSDOSFS_DEBUG 578 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 579 pmp, start, count, fillwith); 580 #endif 581 /* 582 * Be sure the clusters are in the filesystem. 583 */ 584 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 585 return (EINVAL); 586 587 while (count > 0) { 588 byteoffset = FATOFS(pmp, start); 589 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 590 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 591 if (error) { 592 brelse(bp); 593 return (error); 594 } 595 while (count > 0) { 596 start++; 597 newc = --count > 0 ? start : fillwith; 598 switch (pmp->pm_fatmask) { 599 case FAT12_MASK: 600 readcn = getushort(bp->b_data + bo); 601 if (start & 1) { 602 readcn &= 0xf000; 603 readcn |= newc & 0xfff; 604 } else { 605 readcn &= 0x000f; 606 readcn |= newc << 4; 607 } 608 putushort(bp->b_data + bo, readcn); 609 bo++; 610 if (!(start & 1)) 611 bo++; 612 break; 613 case FAT16_MASK: 614 putushort(bp->b_data + bo, newc); 615 bo += 2; 616 break; 617 case FAT32_MASK: 618 readcn = getulong(bp->b_data + bo); 619 readcn &= ~pmp->pm_fatmask; 620 readcn |= newc & pmp->pm_fatmask; 621 putulong(bp->b_data + bo, readcn); 622 bo += 4; 623 break; 624 } 625 if (bo >= bsize) 626 break; 627 } 628 updatefats(pmp, bp, bn); 629 } 630 pmp->pm_fmod = 1; 631 return (0); 632 } 633 634 /* 635 * Check the length of a free cluster chain starting at start. 636 * 637 * pmp - mount point 638 * start - start of chain 639 * count - maximum interesting length 640 */ 641 static int 642 chainlength(struct msdosfsmount *pmp, u_long start, u_long count) 643 { 644 u_long idx, max_idx; 645 u_int map; 646 u_long len; 647 648 MSDOSFS_ASSERT_MP_LOCKED(pmp); 649 650 if (start > pmp->pm_maxcluster) 651 return (0); 652 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 653 idx = start / N_INUSEBITS; 654 start %= N_INUSEBITS; 655 map = pmp->pm_inusemap[idx]; 656 map &= ~((1U << start) - 1); 657 if (map) { 658 len = ffs(map) - 1 - start; 659 len = MIN(len, count); 660 if (start + len > pmp->pm_maxcluster) 661 len = pmp->pm_maxcluster - start + 1; 662 return (len); 663 } 664 len = N_INUSEBITS - start; 665 if (len >= count) { 666 len = count; 667 if (start + len > pmp->pm_maxcluster) 668 len = pmp->pm_maxcluster - start + 1; 669 return (len); 670 } 671 while (++idx <= max_idx) { 672 if (len >= count) 673 break; 674 map = pmp->pm_inusemap[idx]; 675 if (map) { 676 len += ffs(map) - 1; 677 break; 678 } 679 len += N_INUSEBITS; 680 } 681 len = MIN(len, count); 682 if (start + len > pmp->pm_maxcluster) 683 len = pmp->pm_maxcluster - start + 1; 684 return (len); 685 } 686 687 /* 688 * Allocate contigous free clusters. 689 * 690 * pmp - mount point. 691 * start - start of cluster chain. 692 * count - number of clusters to allocate. 693 * fillwith - put this value into the FAT entry for the 694 * last allocated cluster. 695 * retcluster - put the first allocated cluster's number here. 696 * got - how many clusters were actually allocated. 697 */ 698 static int 699 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, 700 u_long fillwith, u_long *retcluster, u_long *got) 701 { 702 int error; 703 u_long cl, n; 704 705 MSDOSFS_ASSERT_MP_LOCKED(pmp); 706 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 707 ("chainalloc on ro msdosfs mount")); 708 709 for (cl = start, n = count; n-- > 0;) 710 usemap_alloc(pmp, cl++); 711 pmp->pm_nxtfree = start + count; 712 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 713 pmp->pm_nxtfree = CLUST_FIRST; 714 pmp->pm_flags |= MSDOSFS_FSIMOD; 715 error = fatchain(pmp, start, count, fillwith); 716 if (error != 0) { 717 for (cl = start, n = count; n-- > 0;) 718 usemap_free(pmp, cl++); 719 return (error); 720 } 721 #ifdef MSDOSFS_DEBUG 722 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 723 start, count); 724 #endif 725 if (retcluster) 726 *retcluster = start; 727 if (got) 728 *got = count; 729 return (0); 730 } 731 732 /* 733 * Allocate contiguous free clusters. 734 * 735 * pmp - mount point. 736 * start - preferred start of cluster chain. 737 * count - number of clusters requested. 738 * fillwith - put this value into the FAT entry for the 739 * last allocated cluster. 740 * retcluster - put the first allocated cluster's number here. 741 * got - how many clusters were actually allocated. 742 */ 743 int 744 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 745 u_long fillwith, u_long *retcluster, u_long *got) 746 { 747 int error; 748 749 MSDOSFS_LOCK_MP(pmp); 750 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 751 MSDOSFS_UNLOCK_MP(pmp); 752 return (error); 753 } 754 755 static int 756 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 757 u_long fillwith, u_long *retcluster, u_long *got) 758 { 759 u_long idx; 760 u_long len, newst, foundl, cn, l; 761 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 762 u_int map; 763 764 MSDOSFS_ASSERT_MP_LOCKED(pmp); 765 766 #ifdef MSDOSFS_DEBUG 767 printf("clusteralloc(): find %lu clusters\n", count); 768 #endif 769 if (start) { 770 if ((len = chainlength(pmp, start, count)) >= count) 771 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 772 } else 773 len = 0; 774 775 newst = pmp->pm_nxtfree; 776 foundl = 0; 777 778 for (cn = newst; cn <= pmp->pm_maxcluster;) { 779 idx = cn / N_INUSEBITS; 780 map = pmp->pm_inusemap[idx]; 781 map |= (1U << (cn % N_INUSEBITS)) - 1; 782 if (map != FULL_RUN) { 783 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 784 if ((l = chainlength(pmp, cn, count)) >= count) 785 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 786 if (l > foundl) { 787 foundcn = cn; 788 foundl = l; 789 } 790 cn += l + 1; 791 continue; 792 } 793 cn += N_INUSEBITS - cn % N_INUSEBITS; 794 } 795 for (cn = 0; cn < newst;) { 796 idx = cn / N_INUSEBITS; 797 map = pmp->pm_inusemap[idx]; 798 map |= (1U << (cn % N_INUSEBITS)) - 1; 799 if (map != FULL_RUN) { 800 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 801 if ((l = chainlength(pmp, cn, count)) >= count) 802 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 803 if (l > foundl) { 804 foundcn = cn; 805 foundl = l; 806 } 807 cn += l + 1; 808 continue; 809 } 810 cn += N_INUSEBITS - cn % N_INUSEBITS; 811 } 812 813 if (!foundl) 814 return (ENOSPC); 815 816 if (len) 817 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 818 else 819 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 820 } 821 822 823 /* 824 * Free a chain of clusters. 825 * 826 * pmp - address of the msdosfs mount structure for the filesystem 827 * containing the cluster chain to be freed. 828 * startcluster - number of the 1st cluster in the chain of clusters to be 829 * freed. 830 */ 831 int 832 freeclusterchain(struct msdosfsmount *pmp, u_long cluster) 833 { 834 int error; 835 struct buf *bp = NULL; 836 u_long bn, bo, bsize, byteoffset; 837 u_long readcn, lbn = -1; 838 839 MSDOSFS_LOCK_MP(pmp); 840 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 841 byteoffset = FATOFS(pmp, cluster); 842 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 843 if (lbn != bn) { 844 if (bp) 845 updatefats(pmp, bp, lbn); 846 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 847 if (error) { 848 brelse(bp); 849 MSDOSFS_UNLOCK_MP(pmp); 850 return (error); 851 } 852 lbn = bn; 853 } 854 usemap_free(pmp, cluster); 855 switch (pmp->pm_fatmask) { 856 case FAT12_MASK: 857 readcn = getushort(bp->b_data + bo); 858 if (cluster & 1) { 859 cluster = readcn >> 4; 860 readcn &= 0x000f; 861 readcn |= MSDOSFSFREE << 4; 862 } else { 863 cluster = readcn; 864 readcn &= 0xf000; 865 readcn |= MSDOSFSFREE & 0xfff; 866 } 867 putushort(bp->b_data + bo, readcn); 868 break; 869 case FAT16_MASK: 870 cluster = getushort(bp->b_data + bo); 871 putushort(bp->b_data + bo, MSDOSFSFREE); 872 break; 873 case FAT32_MASK: 874 cluster = getulong(bp->b_data + bo); 875 putulong(bp->b_data + bo, 876 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 877 break; 878 } 879 cluster &= pmp->pm_fatmask; 880 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 881 cluster |= pmp->pm_fatmask; 882 } 883 if (bp) 884 updatefats(pmp, bp, bn); 885 MSDOSFS_UNLOCK_MP(pmp); 886 return (0); 887 } 888 889 /* 890 * Read in FAT blocks looking for free clusters. For every free cluster 891 * found turn off its corresponding bit in the pm_inusemap. 892 */ 893 int 894 fillinusemap(struct msdosfsmount *pmp) 895 { 896 struct buf *bp; 897 u_long bn, bo, bsize, byteoffset, cn, readcn; 898 int error; 899 900 MSDOSFS_ASSERT_MP_LOCKED(pmp); 901 bp = NULL; 902 903 /* 904 * Mark all clusters in use, we mark the free ones in the FAT scan 905 * loop further down. 906 */ 907 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 908 pmp->pm_inusemap[cn] = FULL_RUN; 909 910 /* 911 * Figure how many free clusters are in the filesystem by ripping 912 * through the FAT counting the number of entries whose content is 913 * zero. These represent free clusters. 914 */ 915 pmp->pm_freeclustercount = 0; 916 for (cn = 0; cn <= pmp->pm_maxcluster; cn++) { 917 byteoffset = FATOFS(pmp, cn); 918 bo = byteoffset % pmp->pm_fatblocksize; 919 if (bo == 0) { 920 /* Read new FAT block */ 921 if (bp != NULL) 922 brelse(bp); 923 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 924 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 925 if (error != 0) 926 return (error); 927 } 928 if (FAT32(pmp)) 929 readcn = getulong(bp->b_data + bo); 930 else 931 readcn = getushort(bp->b_data + bo); 932 if (FAT12(pmp) && (cn & 1)) 933 readcn >>= 4; 934 readcn &= pmp->pm_fatmask; 935 936 /* 937 * Check if the FAT ID matches the BPB's media descriptor and 938 * all other bits are set to 1. 939 */ 940 if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) | 941 pmp->pm_bpb.bpbMedia)) { 942 #ifdef MSDOSFS_DEBUG 943 printf("mountmsdosfs(): Media descriptor in BPB" 944 "does not match FAT ID\n"); 945 #endif 946 brelse(bp); 947 return (EINVAL); 948 } else if (readcn == CLUST_FREE) 949 usemap_free(pmp, cn); 950 } 951 if (bp != NULL) 952 brelse(bp); 953 954 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster + 955 N_INUSEBITS) / N_INUSEBITS; cn++) 956 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 957 958 return (0); 959 } 960 961 /* 962 * Allocate a new cluster and chain it onto the end of the file. 963 * 964 * dep - the file to extend 965 * count - number of clusters to allocate 966 * bpp - where to return the address of the buf header for the first new 967 * file block 968 * ncp - where to put cluster number of the first newly allocated cluster 969 * If this pointer is 0, do not return the cluster number. 970 * flags - see fat.h 971 * 972 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 973 * the de_flag field of the denode and it does not change the de_FileSize 974 * field. This is left for the caller to do. 975 */ 976 int 977 extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp, 978 int flags) 979 { 980 int error; 981 u_long frcn; 982 u_long cn, got; 983 struct msdosfsmount *pmp = dep->de_pmp; 984 struct buf *bp; 985 daddr_t blkno; 986 987 /* 988 * Don't try to extend the root directory 989 */ 990 if (dep->de_StartCluster == MSDOSFSROOT 991 && (dep->de_Attributes & ATTR_DIRECTORY)) { 992 #ifdef MSDOSFS_DEBUG 993 printf("extendfile(): attempt to extend root directory\n"); 994 #endif 995 return (ENOSPC); 996 } 997 998 /* 999 * If the "file's last cluster" cache entry is empty, and the file 1000 * is not empty, then fill the cache entry by calling pcbmap(). 1001 */ 1002 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 1003 dep->de_StartCluster != 0) { 1004 error = pcbmap(dep, 0xffff, 0, &cn, 0); 1005 /* we expect it to return E2BIG */ 1006 if (error != E2BIG) 1007 return (error); 1008 } 1009 1010 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 1011 dep->de_fc[FC_LASTFC].fc_frcn; 1012 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 1013 dep->de_fc[FC_LASTFC].fc_fsrcn; 1014 while (count > 0) { 1015 /* 1016 * Allocate a new cluster chain and cat onto the end of the 1017 * file. If the file is empty we make de_StartCluster point 1018 * to the new block. Note that de_StartCluster being 0 is 1019 * sufficient to be sure the file is empty since we exclude 1020 * attempts to extend the root directory above, and the root 1021 * dir is the only file with a startcluster of 0 that has 1022 * blocks allocated (sort of). 1023 */ 1024 if (dep->de_StartCluster == 0) 1025 cn = 0; 1026 else 1027 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1028 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1029 if (error) 1030 return (error); 1031 1032 count -= got; 1033 1034 /* 1035 * Give them the filesystem relative cluster number if they want 1036 * it. 1037 */ 1038 if (ncp) { 1039 *ncp = cn; 1040 ncp = NULL; 1041 } 1042 1043 if (dep->de_StartCluster == 0) { 1044 dep->de_StartCluster = cn; 1045 frcn = 0; 1046 } else { 1047 error = fatentry(FAT_SET, pmp, 1048 dep->de_fc[FC_LASTFC].fc_fsrcn, 1049 0, cn); 1050 if (error) { 1051 clusterfree(pmp, cn, NULL); 1052 return (error); 1053 } 1054 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1055 } 1056 1057 /* 1058 * Update the "last cluster of the file" entry in the 1059 * denode's FAT cache. 1060 */ 1061 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1062 1063 if (flags & DE_CLEAR) { 1064 while (got-- > 0) { 1065 /* 1066 * Get the buf header for the new block of the file. 1067 */ 1068 if (dep->de_Attributes & ATTR_DIRECTORY) 1069 bp = getblk(pmp->pm_devvp, 1070 cntobn(pmp, cn++), 1071 pmp->pm_bpcluster, 0, 0, 0); 1072 else { 1073 bp = getblk(DETOV(dep), 1074 frcn++, 1075 pmp->pm_bpcluster, 0, 0, 0); 1076 /* 1077 * Do the bmap now, as in msdosfs_write 1078 */ 1079 if (pcbmap(dep, 1080 bp->b_lblkno, 1081 &blkno, 0, 0)) 1082 bp->b_blkno = -1; 1083 if (bp->b_blkno == -1) 1084 panic("extendfile: pcbmap"); 1085 else 1086 bp->b_blkno = blkno; 1087 } 1088 clrbuf(bp); 1089 if (bpp) { 1090 *bpp = bp; 1091 bpp = NULL; 1092 } else { 1093 bdwrite(bp); 1094 } 1095 if (vm_page_count_severe() || 1096 buf_dirty_count_severe()) 1097 vn_fsync_buf(DETOV(dep), MNT_WAIT); 1098 } 1099 } 1100 } 1101 1102 return (0); 1103 } 1104 1105 /*- 1106 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1107 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1108 * this bit is not defined for FAT12 volumes, which are always assumed to 1109 * be clean. 1110 * 1111 * The fatentry() routine only works on cluster numbers that a file could 1112 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1113 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1114 * 1115 * Inputs: 1116 * pmp The MS-DOS volume to mark 1117 * dirty Non-zero if the volume should be marked dirty; zero if it 1118 * should be marked clean 1119 * 1120 * Result: 1121 * 0 Success 1122 * EROFS Volume is read-only 1123 * ? (other errors from called routines) 1124 */ 1125 int 1126 markvoldirty(struct msdosfsmount *pmp, int dirty) 1127 { 1128 struct buf *bp; 1129 u_long bn, bo, bsize, byteoffset, fatval; 1130 int error; 1131 1132 /* 1133 * FAT12 does not support a "clean" bit, so don't do anything for 1134 * FAT12. 1135 */ 1136 if (FAT12(pmp)) 1137 return (0); 1138 1139 /* Can't change the bit on a read-only filesystem. */ 1140 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1141 return (EROFS); 1142 1143 /* 1144 * Fetch the block containing the FAT entry. It is given by the 1145 * pseudo-cluster 1. 1146 */ 1147 byteoffset = FATOFS(pmp, 1); 1148 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1149 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1150 if (error) { 1151 brelse(bp); 1152 return (error); 1153 } 1154 1155 /* 1156 * Get the current value of the FAT entry and set/clear the relevant 1157 * bit. Dirty means clear the "clean" bit; clean means set the 1158 * "clean" bit. 1159 */ 1160 if (FAT32(pmp)) { 1161 /* FAT32 uses bit 27. */ 1162 fatval = getulong(&bp->b_data[bo]); 1163 if (dirty) 1164 fatval &= 0xF7FFFFFF; 1165 else 1166 fatval |= 0x08000000; 1167 putulong(&bp->b_data[bo], fatval); 1168 } else { 1169 /* Must be FAT16; use bit 15. */ 1170 fatval = getushort(&bp->b_data[bo]); 1171 if (dirty) 1172 fatval &= 0x7FFF; 1173 else 1174 fatval |= 0x8000; 1175 putushort(&bp->b_data[bo], fatval); 1176 } 1177 1178 /* Write out the modified FAT block synchronously. */ 1179 return (bwrite(bp)); 1180 }
Cache object: 8cff90d069a08e165f76bd4919114a67
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]