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 * 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/vmmeter.h> 56 #include <sys/vnode.h> 57 58 #include <fs/msdosfs/bpb.h> 59 #include <fs/msdosfs/direntry.h> 60 #include <fs/msdosfs/denode.h> 61 #include <fs/msdosfs/fat.h> 62 #include <fs/msdosfs/msdosfsmount.h> 63 64 #define FULL_RUN ((u_int)0xffffffff) 65 66 static int chainalloc(struct msdosfsmount *pmp, u_long start, 67 u_long count, u_long fillwith, u_long *retcluster, 68 u_long *got); 69 static int chainlength(struct msdosfsmount *pmp, u_long start, 70 u_long count); 71 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 72 u_long *sizep, u_long *bop); 73 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 74 u_long fillwith); 75 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 76 u_long *fsrcnp); 77 static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 78 u_long fatbn); 79 static __inline void 80 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 81 static __inline void 82 usemap_free(struct msdosfsmount *pmp, u_long cn); 83 static int clusteralloc1(struct msdosfsmount *pmp, u_long start, 84 u_long count, u_long fillwith, u_long *retcluster, 85 u_long *got); 86 87 static void 88 fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep, 89 u_long *bop) 90 { 91 u_long bn, size; 92 93 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 94 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 95 * DEV_BSIZE; 96 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 97 98 if (bnp) 99 *bnp = bn; 100 if (sizep) 101 *sizep = size; 102 if (bop) 103 *bop = ofs % pmp->pm_fatblocksize; 104 } 105 106 /* 107 * Map the logical cluster number of a file into a physical disk sector 108 * that is filesystem relative. 109 * 110 * dep - address of denode representing the file of interest 111 * findcn - file relative cluster whose filesystem relative cluster number 112 * and/or block number are/is to be found 113 * bnp - address of where to place the filesystem relative block number. 114 * If this pointer is null then don't return this quantity. 115 * cnp - address of where to place the filesystem relative cluster number. 116 * If this pointer is null then don't return this quantity. 117 * sp - pointer to returned block size 118 * 119 * NOTE: Either bnp or cnp must be non-null. 120 * This function has one side effect. If the requested file relative cluster 121 * is beyond the end of file, then the actual number of clusters in the file 122 * is returned in *cnp. This is useful for determining how long a directory is. 123 * If cnp is null, nothing is returned. 124 */ 125 int 126 pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp) 127 { 128 int error; 129 u_long i; 130 u_long cn; 131 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 132 u_long byteoffset; 133 u_long bn; 134 u_long bo; 135 struct buf *bp = NULL; 136 u_long bp_bn = -1; 137 struct msdosfsmount *pmp = dep->de_pmp; 138 u_long bsize; 139 140 KASSERT(bnp != NULL || cnp != NULL || sp != NULL, 141 ("pcbmap: extra call")); 142 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap"); 143 144 cn = dep->de_StartCluster; 145 /* 146 * The "file" that makes up the root directory is contiguous, 147 * permanently allocated, of fixed size, and is not made up of 148 * clusters. If the cluster number is beyond the end of the root 149 * directory, then return the number of clusters in the file. 150 */ 151 if (cn == MSDOSFSROOT) { 152 if (dep->de_Attributes & ATTR_DIRECTORY) { 153 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 154 if (cnp) 155 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 156 return (E2BIG); 157 } 158 if (bnp) 159 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 160 if (cnp) 161 *cnp = MSDOSFSROOT; 162 if (sp) 163 *sp = min(pmp->pm_bpcluster, 164 dep->de_FileSize - de_cn2off(pmp, findcn)); 165 return (0); 166 } else { /* just an empty file */ 167 if (cnp) 168 *cnp = 0; 169 return (E2BIG); 170 } 171 } 172 173 /* 174 * All other files do I/O in cluster sized blocks 175 */ 176 if (sp) 177 *sp = pmp->pm_bpcluster; 178 179 /* 180 * Rummage around in the fat cache, maybe we can avoid tromping 181 * through every fat entry for the file. And, keep track of how far 182 * off the cache was from where we wanted to be. 183 */ 184 i = 0; 185 fc_lookup(dep, findcn, &i, &cn); 186 187 /* 188 * Handle all other files or directories the normal way. 189 */ 190 for (; i < findcn; i++) { 191 /* 192 * Stop with all reserved clusters, not just with EOF. 193 */ 194 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 195 goto hiteof; 196 byteoffset = FATOFS(pmp, cn); 197 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 198 if (bn != bp_bn) { 199 if (bp) 200 brelse(bp); 201 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 202 if (error) { 203 brelse(bp); 204 return (error); 205 } 206 bp_bn = bn; 207 } 208 prevcn = cn; 209 if (bo >= bsize) { 210 if (bp) 211 brelse(bp); 212 return (EIO); 213 } 214 if (FAT32(pmp)) 215 cn = getulong(&bp->b_data[bo]); 216 else 217 cn = getushort(&bp->b_data[bo]); 218 if (FAT12(pmp) && (prevcn & 1)) 219 cn >>= 4; 220 cn &= pmp->pm_fatmask; 221 222 /* 223 * Force the special cluster numbers 224 * to be the same for all cluster sizes 225 * to let the rest of msdosfs handle 226 * all cases the same. 227 */ 228 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 229 cn |= ~pmp->pm_fatmask; 230 } 231 232 if (!MSDOSFSEOF(pmp, cn)) { 233 if (bp) 234 brelse(bp); 235 if (bnp) 236 *bnp = cntobn(pmp, cn); 237 if (cnp) 238 *cnp = cn; 239 fc_setcache(dep, FC_LASTMAP, i, cn); 240 return (0); 241 } 242 243 hiteof:; 244 if (cnp) 245 *cnp = i; 246 if (bp) 247 brelse(bp); 248 /* update last file cluster entry in the fat cache */ 249 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 250 return (E2BIG); 251 } 252 253 /* 254 * Find the closest entry in the fat cache to the cluster we are looking 255 * for. 256 */ 257 static void 258 fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp) 259 { 260 int i; 261 u_long cn; 262 struct fatcache *closest = NULL; 263 264 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup"); 265 266 for (i = 0; i < FC_SIZE; i++) { 267 cn = dep->de_fc[i].fc_frcn; 268 if (cn != FCE_EMPTY && cn <= findcn) { 269 if (closest == NULL || cn > closest->fc_frcn) 270 closest = &dep->de_fc[i]; 271 } 272 } 273 if (closest) { 274 *frcnp = closest->fc_frcn; 275 *fsrcnp = closest->fc_fsrcn; 276 } 277 } 278 279 /* 280 * Purge the fat cache in denode dep of all entries relating to file 281 * relative cluster frcn and beyond. 282 */ 283 void 284 fc_purge(struct denode *dep, u_int frcn) 285 { 286 int i; 287 struct fatcache *fcp; 288 289 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge"); 290 291 fcp = dep->de_fc; 292 for (i = 0; i < FC_SIZE; i++, fcp++) { 293 if (fcp->fc_frcn >= frcn) 294 fcp->fc_frcn = FCE_EMPTY; 295 } 296 } 297 298 /* 299 * Update the fat. 300 * If mirroring the fat, update all copies, with the first copy as last. 301 * Else update only the current fat (ignoring the others). 302 * 303 * pmp - msdosfsmount structure for filesystem to update 304 * bp - addr of modified fat block 305 * fatbn - block number relative to begin of filesystem of the modified fat block. 306 */ 307 static void 308 updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn) 309 { 310 struct buf *bpn; 311 int cleanfat, i; 312 313 #ifdef MSDOSFS_DEBUG 314 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 315 #endif 316 317 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 318 /* 319 * Now copy the block(s) of the modified fat to the other copies of 320 * the fat and write them out. This is faster than reading in the 321 * other fats and then writing them back out. This could tie up 322 * the fat for quite a while. Preventing others from accessing it. 323 * To prevent us from going after the fat quite so much we use 324 * delayed writes, unless they specfied "synchronous" when the 325 * filesystem was mounted. If synch is asked for then use 326 * bwrite()'s and really slow things down. 327 */ 328 if (fatbn != pmp->pm_fatblk || FAT12(pmp)) 329 cleanfat = 0; 330 else if (FAT16(pmp)) 331 cleanfat = 16; 332 else 333 cleanfat = 32; 334 for (i = 1; i < pmp->pm_FATs; i++) { 335 fatbn += pmp->pm_FATsecs; 336 /* getblk() never fails */ 337 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 338 0, 0, 0); 339 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 340 /* Force the clean bit on in the other copies. */ 341 if (cleanfat == 16) 342 ((u_int8_t *)bpn->b_data)[3] |= 0x80; 343 else if (cleanfat == 32) 344 ((u_int8_t *)bpn->b_data)[7] |= 0x08; 345 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 346 bwrite(bpn); 347 else 348 bdwrite(bpn); 349 } 350 } 351 352 /* 353 * Write out the first (or current) fat last. 354 */ 355 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 356 bwrite(bp); 357 else 358 bdwrite(bp); 359 } 360 361 /* 362 * Updating entries in 12 bit fats is a pain in the butt. 363 * 364 * The following picture shows where nibbles go when moving from a 12 bit 365 * cluster number into the appropriate bytes in the FAT. 366 * 367 * byte m byte m+1 byte m+2 368 * +----+----+ +----+----+ +----+----+ 369 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 370 * +----+----+ +----+----+ +----+----+ 371 * 372 * +----+----+----+ +----+----+----+ 373 * | 3 0 1 | | 4 5 2 | 374 * +----+----+----+ +----+----+----+ 375 * cluster n cluster n+1 376 * 377 * Where n is even. m = n + (n >> 2) 378 * 379 */ 380 static __inline void 381 usemap_alloc(struct msdosfsmount *pmp, u_long cn) 382 { 383 384 MSDOSFS_ASSERT_MP_LOCKED(pmp); 385 386 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 387 pmp->pm_maxcluster)); 388 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 389 ("usemap_alloc on ro msdosfs mount")); 390 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & 391 (1U << (cn % N_INUSEBITS))) == 0, 392 ("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] & 413 (1U << (cn % N_INUSEBITS))) != 0, 414 ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS, 415 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 416 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1U << (cn % N_INUSEBITS)); 417 } 418 419 int 420 clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp) 421 { 422 int error; 423 u_long oldcn; 424 425 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 426 if (error) 427 return (error); 428 /* 429 * If the cluster was successfully marked free, then update 430 * the count of free clusters, and turn off the "allocated" 431 * bit in the "in use" cluster bit map. 432 */ 433 MSDOSFS_LOCK_MP(pmp); 434 usemap_free(pmp, cluster); 435 MSDOSFS_UNLOCK_MP(pmp); 436 if (oldcnp) 437 *oldcnp = oldcn; 438 return (0); 439 } 440 441 /* 442 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 443 * 444 * function - whether to get or set a fat entry 445 * pmp - address of the msdosfsmount structure for the filesystem 446 * whose fat is to be manipulated. 447 * cn - which cluster is of interest 448 * oldcontents - address of a word that is to receive the contents of the 449 * cluster'th entry if this is a get function 450 * newcontents - the new value to be written into the cluster'th element of 451 * the fat if this is a set function. 452 * 453 * This function can also be used to free a cluster by setting the fat entry 454 * for a cluster to 0. 455 * 456 * All copies of the fat are updated if this is a set function. NOTE: If 457 * fatentry() marks a cluster as free it does not update the inusemap in 458 * the msdosfsmount structure. This is left to the caller. 459 */ 460 int 461 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, 462 u_long newcontents) 463 { 464 int error; 465 u_long readcn; 466 u_long bn, bo, bsize, byteoffset; 467 struct buf *bp; 468 469 #ifdef MSDOSFS_DEBUG 470 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 471 function, pmp, cn, oldcontents, newcontents); 472 #endif 473 474 #ifdef DIAGNOSTIC 475 /* 476 * Be sure they asked us to do something. 477 */ 478 if ((function & (FAT_SET | FAT_GET)) == 0) { 479 #ifdef MSDOSFS_DEBUG 480 printf("fatentry(): function code doesn't specify get or set\n"); 481 #endif 482 return (EINVAL); 483 } 484 485 /* 486 * If they asked us to return a cluster number but didn't tell us 487 * where to put it, give them an error. 488 */ 489 if ((function & FAT_GET) && oldcontents == NULL) { 490 #ifdef MSDOSFS_DEBUG 491 printf("fatentry(): get function with no place to put result\n"); 492 #endif 493 return (EINVAL); 494 } 495 #endif 496 497 /* 498 * Be sure the requested cluster is in the filesystem. 499 */ 500 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 501 return (EINVAL); 502 503 byteoffset = FATOFS(pmp, cn); 504 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 505 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 506 if (error) { 507 brelse(bp); 508 return (error); 509 } 510 511 if (function & FAT_GET) { 512 if (FAT32(pmp)) 513 readcn = getulong(&bp->b_data[bo]); 514 else 515 readcn = getushort(&bp->b_data[bo]); 516 if (FAT12(pmp) & (cn & 1)) 517 readcn >>= 4; 518 readcn &= pmp->pm_fatmask; 519 /* map reserved fat entries to same values for all fats */ 520 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 521 readcn |= ~pmp->pm_fatmask; 522 *oldcontents = readcn; 523 } 524 if (function & FAT_SET) { 525 switch (pmp->pm_fatmask) { 526 case FAT12_MASK: 527 readcn = getushort(&bp->b_data[bo]); 528 if (cn & 1) { 529 readcn &= 0x000f; 530 readcn |= newcontents << 4; 531 } else { 532 readcn &= 0xf000; 533 readcn |= newcontents & 0xfff; 534 } 535 putushort(&bp->b_data[bo], readcn); 536 break; 537 case FAT16_MASK: 538 putushort(&bp->b_data[bo], newcontents); 539 break; 540 case FAT32_MASK: 541 /* 542 * According to spec we have to retain the 543 * high order bits of the fat entry. 544 */ 545 readcn = getulong(&bp->b_data[bo]); 546 readcn &= ~FAT32_MASK; 547 readcn |= newcontents & FAT32_MASK; 548 putulong(&bp->b_data[bo], readcn); 549 break; 550 } 551 updatefats(pmp, bp, bn); 552 bp = NULL; 553 pmp->pm_fmod = 1; 554 } 555 if (bp) 556 brelse(bp); 557 return (0); 558 } 559 560 /* 561 * Update a contiguous cluster chain 562 * 563 * pmp - mount point 564 * start - first cluster of chain 565 * count - number of clusters in chain 566 * fillwith - what to write into fat entry of last cluster 567 */ 568 static int 569 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) 570 { 571 int error; 572 u_long bn, bo, bsize, byteoffset, readcn, newc; 573 struct buf *bp; 574 575 #ifdef MSDOSFS_DEBUG 576 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 577 pmp, start, count, fillwith); 578 #endif 579 /* 580 * Be sure the clusters are in the filesystem. 581 */ 582 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 583 return (EINVAL); 584 585 while (count > 0) { 586 byteoffset = FATOFS(pmp, start); 587 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 588 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 589 if (error) { 590 brelse(bp); 591 return (error); 592 } 593 while (count > 0) { 594 start++; 595 newc = --count > 0 ? start : fillwith; 596 switch (pmp->pm_fatmask) { 597 case FAT12_MASK: 598 readcn = getushort(&bp->b_data[bo]); 599 if (start & 1) { 600 readcn &= 0xf000; 601 readcn |= newc & 0xfff; 602 } else { 603 readcn &= 0x000f; 604 readcn |= newc << 4; 605 } 606 putushort(&bp->b_data[bo], readcn); 607 bo++; 608 if (!(start & 1)) 609 bo++; 610 break; 611 case FAT16_MASK: 612 putushort(&bp->b_data[bo], newc); 613 bo += 2; 614 break; 615 case FAT32_MASK: 616 readcn = getulong(&bp->b_data[bo]); 617 readcn &= ~pmp->pm_fatmask; 618 readcn |= newc & pmp->pm_fatmask; 619 putulong(&bp->b_data[bo], readcn); 620 bo += 4; 621 break; 622 } 623 if (bo >= bsize) 624 break; 625 } 626 updatefats(pmp, bp, bn); 627 } 628 pmp->pm_fmod = 1; 629 return (0); 630 } 631 632 /* 633 * Check the length of a free cluster chain starting at start. 634 * 635 * pmp - mount point 636 * start - start of chain 637 * count - maximum interesting length 638 */ 639 static int 640 chainlength(struct msdosfsmount *pmp, u_long start, u_long count) 641 { 642 u_long idx, max_idx; 643 u_int map; 644 u_long len; 645 646 MSDOSFS_ASSERT_MP_LOCKED(pmp); 647 648 if (start > pmp->pm_maxcluster) 649 return (0); 650 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 651 idx = start / N_INUSEBITS; 652 start %= N_INUSEBITS; 653 map = pmp->pm_inusemap[idx]; 654 map &= ~((1U << start) - 1); 655 if (map) { 656 len = ffs(map) - 1 - start; 657 len = MIN(len, count); 658 if (start + len > pmp->pm_maxcluster) 659 len = pmp->pm_maxcluster - start + 1; 660 return (len); 661 } 662 len = N_INUSEBITS - start; 663 if (len >= count) { 664 len = count; 665 if (start + len > pmp->pm_maxcluster) 666 len = pmp->pm_maxcluster - start + 1; 667 return (len); 668 } 669 while (++idx <= max_idx) { 670 if (len >= count) 671 break; 672 map = pmp->pm_inusemap[idx]; 673 if (map) { 674 len += ffs(map) - 1; 675 break; 676 } 677 len += N_INUSEBITS; 678 } 679 len = MIN(len, count); 680 if (start + len > pmp->pm_maxcluster) 681 len = pmp->pm_maxcluster - start + 1; 682 return (len); 683 } 684 685 /* 686 * Allocate contigous free clusters. 687 * 688 * pmp - mount point. 689 * start - start of cluster chain. 690 * count - number of clusters to allocate. 691 * fillwith - put this value into the fat entry for the 692 * last allocated cluster. 693 * retcluster - put the first allocated cluster's number here. 694 * got - how many clusters were actually allocated. 695 */ 696 static int 697 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, 698 u_long fillwith, u_long *retcluster, u_long *got) 699 { 700 int error; 701 u_long cl, n; 702 703 MSDOSFS_ASSERT_MP_LOCKED(pmp); 704 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 705 ("chainalloc on ro msdosfs mount")); 706 707 for (cl = start, n = count; n-- > 0;) 708 usemap_alloc(pmp, cl++); 709 pmp->pm_nxtfree = start + count; 710 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 711 pmp->pm_nxtfree = CLUST_FIRST; 712 pmp->pm_flags |= MSDOSFS_FSIMOD; 713 error = fatchain(pmp, start, count, fillwith); 714 if (error != 0) { 715 for (cl = start, n = count; n-- > 0;) 716 usemap_free(pmp, cl++); 717 return (error); 718 } 719 #ifdef MSDOSFS_DEBUG 720 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 721 start, count); 722 #endif 723 if (retcluster) 724 *retcluster = start; 725 if (got) 726 *got = count; 727 return (0); 728 } 729 730 /* 731 * Allocate contiguous free clusters. 732 * 733 * pmp - mount point. 734 * start - preferred start of cluster chain. 735 * count - number of clusters requested. 736 * fillwith - put this value into the fat entry for the 737 * last allocated cluster. 738 * retcluster - put the first allocated cluster's number here. 739 * got - how many clusters were actually allocated. 740 */ 741 int 742 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 743 u_long fillwith, u_long *retcluster, u_long *got) 744 { 745 int error; 746 747 MSDOSFS_LOCK_MP(pmp); 748 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 749 MSDOSFS_UNLOCK_MP(pmp); 750 return (error); 751 } 752 753 static int 754 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 755 u_long fillwith, u_long *retcluster, u_long *got) 756 { 757 u_long idx; 758 u_long len, newst, foundl, cn, l; 759 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 760 u_int map; 761 762 MSDOSFS_ASSERT_MP_LOCKED(pmp); 763 764 #ifdef MSDOSFS_DEBUG 765 printf("clusteralloc(): find %lu clusters\n", count); 766 #endif 767 if (start) { 768 if ((len = chainlength(pmp, start, count)) >= count) 769 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 770 } else 771 len = 0; 772 773 newst = pmp->pm_nxtfree; 774 foundl = 0; 775 776 for (cn = newst; cn <= pmp->pm_maxcluster;) { 777 idx = cn / N_INUSEBITS; 778 map = pmp->pm_inusemap[idx]; 779 map |= (1U << (cn % N_INUSEBITS)) - 1; 780 if (map != FULL_RUN) { 781 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 782 if ((l = chainlength(pmp, cn, count)) >= count) 783 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 784 if (l > foundl) { 785 foundcn = cn; 786 foundl = l; 787 } 788 cn += l + 1; 789 continue; 790 } 791 cn += N_INUSEBITS - cn % N_INUSEBITS; 792 } 793 for (cn = 0; cn < newst;) { 794 idx = cn / N_INUSEBITS; 795 map = pmp->pm_inusemap[idx]; 796 map |= (1U << (cn % N_INUSEBITS)) - 1; 797 if (map != FULL_RUN) { 798 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 799 if ((l = chainlength(pmp, cn, count)) >= count) 800 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 801 if (l > foundl) { 802 foundcn = cn; 803 foundl = l; 804 } 805 cn += l + 1; 806 continue; 807 } 808 cn += N_INUSEBITS - cn % N_INUSEBITS; 809 } 810 811 if (!foundl) 812 return (ENOSPC); 813 814 if (len) 815 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 816 else 817 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 818 } 819 820 821 /* 822 * Free a chain of clusters. 823 * 824 * pmp - address of the msdosfs mount structure for the filesystem 825 * containing the cluster chain to be freed. 826 * startcluster - number of the 1st cluster in the chain of clusters to be 827 * freed. 828 */ 829 int 830 freeclusterchain(struct msdosfsmount *pmp, u_long cluster) 831 { 832 int error; 833 struct buf *bp = NULL; 834 u_long bn, bo, bsize, byteoffset; 835 u_long readcn, lbn = -1; 836 837 MSDOSFS_LOCK_MP(pmp); 838 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 839 byteoffset = FATOFS(pmp, cluster); 840 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 841 if (lbn != bn) { 842 if (bp) 843 updatefats(pmp, bp, lbn); 844 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 845 if (error) { 846 brelse(bp); 847 MSDOSFS_UNLOCK_MP(pmp); 848 return (error); 849 } 850 lbn = bn; 851 } 852 usemap_free(pmp, cluster); 853 switch (pmp->pm_fatmask) { 854 case FAT12_MASK: 855 readcn = getushort(&bp->b_data[bo]); 856 if (cluster & 1) { 857 cluster = readcn >> 4; 858 readcn &= 0x000f; 859 readcn |= MSDOSFSFREE << 4; 860 } else { 861 cluster = readcn; 862 readcn &= 0xf000; 863 readcn |= MSDOSFSFREE & 0xfff; 864 } 865 putushort(&bp->b_data[bo], readcn); 866 break; 867 case FAT16_MASK: 868 cluster = getushort(&bp->b_data[bo]); 869 putushort(&bp->b_data[bo], MSDOSFSFREE); 870 break; 871 case FAT32_MASK: 872 cluster = getulong(&bp->b_data[bo]); 873 putulong(&bp->b_data[bo], 874 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 875 break; 876 } 877 cluster &= pmp->pm_fatmask; 878 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 879 cluster |= pmp->pm_fatmask; 880 } 881 if (bp) 882 updatefats(pmp, bp, bn); 883 MSDOSFS_UNLOCK_MP(pmp); 884 return (0); 885 } 886 887 /* 888 * Read in fat blocks looking for free clusters. For every free cluster 889 * found turn off its corresponding bit in the pm_inusemap. 890 */ 891 int 892 fillinusemap(struct msdosfsmount *pmp) 893 { 894 struct buf *bp; 895 u_long bn, bo, bsize, byteoffset, cn, readcn; 896 int error; 897 898 MSDOSFS_ASSERT_MP_LOCKED(pmp); 899 bp = NULL; 900 901 /* 902 * Mark all clusters in use, we mark the free ones in the fat scan 903 * loop further down. 904 */ 905 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 906 pmp->pm_inusemap[cn] = FULL_RUN; 907 908 /* 909 * Figure how many free clusters are in the filesystem by ripping 910 * through the fat counting the number of entries whose content is 911 * zero. These represent free clusters. 912 */ 913 pmp->pm_freeclustercount = 0; 914 for (cn = 0; cn <= pmp->pm_maxcluster; cn++) { 915 byteoffset = FATOFS(pmp, cn); 916 bo = byteoffset % pmp->pm_fatblocksize; 917 if (bo == 0) { 918 /* Read new FAT block */ 919 if (bp != NULL) 920 brelse(bp); 921 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 922 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 923 if (error != 0) 924 return (error); 925 } 926 if (FAT32(pmp)) 927 readcn = getulong(&bp->b_data[bo]); 928 else 929 readcn = getushort(&bp->b_data[bo]); 930 if (FAT12(pmp) && (cn & 1)) 931 readcn >>= 4; 932 readcn &= pmp->pm_fatmask; 933 934 /* 935 * Check if the FAT ID matches the BPB's media descriptor and 936 * all other bits are set to 1. 937 */ 938 if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) | 939 pmp->pm_bpb.bpbMedia)) { 940 #ifdef MSDOSFS_DEBUG 941 printf("mountmsdosfs(): Media descriptor in BPB" 942 "does not match FAT ID\n"); 943 #endif 944 brelse(bp); 945 return (EINVAL); 946 } else if (readcn == CLUST_FREE) 947 usemap_free(pmp, cn); 948 } 949 if (bp != NULL) 950 brelse(bp); 951 952 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster + 953 N_INUSEBITS) / N_INUSEBITS; cn++) 954 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 955 956 return (0); 957 } 958 959 /* 960 * Allocate a new cluster and chain it onto the end of the file. 961 * 962 * dep - the file to extend 963 * count - number of clusters to allocate 964 * bpp - where to return the address of the buf header for the first new 965 * file block 966 * ncp - where to put cluster number of the first newly allocated cluster 967 * If this pointer is 0, do not return the cluster number. 968 * flags - see fat.h 969 * 970 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 971 * the de_flag field of the denode and it does not change the de_FileSize 972 * field. This is left for the caller to do. 973 */ 974 int 975 extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp, 976 int flags) 977 { 978 int error; 979 u_long frcn; 980 u_long cn, got; 981 struct msdosfsmount *pmp = dep->de_pmp; 982 struct buf *bp; 983 struct vop_fsync_args fsync_ap; 984 daddr_t blkno; 985 986 /* 987 * Don't try to extend the root directory 988 */ 989 if (dep->de_StartCluster == MSDOSFSROOT 990 && (dep->de_Attributes & ATTR_DIRECTORY)) { 991 #ifdef MSDOSFS_DEBUG 992 printf("extendfile(): attempt to extend root directory\n"); 993 #endif 994 return (ENOSPC); 995 } 996 997 /* 998 * If the "file's last cluster" cache entry is empty, and the file 999 * is not empty, then fill the cache entry by calling pcbmap(). 1000 */ 1001 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 1002 dep->de_StartCluster != 0) { 1003 error = pcbmap(dep, 0xffff, 0, &cn, 0); 1004 /* we expect it to return E2BIG */ 1005 if (error != E2BIG) 1006 return (error); 1007 } 1008 1009 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 1010 dep->de_fc[FC_LASTFC].fc_frcn; 1011 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 1012 dep->de_fc[FC_LASTFC].fc_fsrcn; 1013 while (count > 0) { 1014 /* 1015 * Allocate a new cluster chain and cat onto the end of the 1016 * file. 1017 * If the file is empty we make de_StartCluster point 1018 * to the new block. Note that de_StartCluster being 1019 * 0 is sufficient to be sure the file is empty since 1020 * we exclude attempts to extend the root directory 1021 * above, and the root dir is the only file with a 1022 * startcluster of 0 that has blocks allocated (sort 1023 * of). 1024 */ 1025 if (dep->de_StartCluster == 0) 1026 cn = 0; 1027 else 1028 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1029 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1030 if (error) 1031 return (error); 1032 1033 count -= got; 1034 1035 /* 1036 * Give them the filesystem relative cluster number if they want 1037 * it. 1038 */ 1039 if (ncp) { 1040 *ncp = cn; 1041 ncp = NULL; 1042 } 1043 1044 if (dep->de_StartCluster == 0) { 1045 dep->de_StartCluster = cn; 1046 frcn = 0; 1047 } else { 1048 error = fatentry(FAT_SET, pmp, 1049 dep->de_fc[FC_LASTFC].fc_fsrcn, 1050 0, cn); 1051 if (error) { 1052 clusterfree(pmp, cn, NULL); 1053 return (error); 1054 } 1055 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1056 } 1057 1058 /* 1059 * Update the "last cluster of the file" entry in the denode's fat 1060 * cache. 1061 */ 1062 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1063 1064 if (flags & DE_CLEAR) { 1065 while (got-- > 0) { 1066 /* 1067 * Get the buf header for the new block of the file. 1068 */ 1069 if (dep->de_Attributes & ATTR_DIRECTORY) 1070 bp = getblk(pmp->pm_devvp, 1071 cntobn(pmp, cn++), 1072 pmp->pm_bpcluster, 0, 0, 0); 1073 else { 1074 bp = getblk(DETOV(dep), 1075 frcn++, 1076 pmp->pm_bpcluster, 0, 0, 0); 1077 /* 1078 * Do the bmap now, as in msdosfs_write 1079 */ 1080 if (pcbmap(dep, 1081 bp->b_lblkno, 1082 &blkno, 0, 0)) 1083 bp->b_blkno = -1; 1084 if (bp->b_blkno == -1) 1085 panic("extendfile: pcbmap"); 1086 else 1087 bp->b_blkno = blkno; 1088 } 1089 vfs_bio_clrbuf(bp); 1090 if (bpp) { 1091 *bpp = bp; 1092 bpp = NULL; 1093 } else { 1094 bdwrite(bp); 1095 } 1096 if (vm_page_count_severe() || 1097 buf_dirty_count_severe()) { 1098 fsync_ap.a_vp = DETOV(dep); 1099 fsync_ap.a_waitfor = MNT_WAIT; 1100 fsync_ap.a_td = curthread; 1101 vop_stdfsync(&fsync_ap); 1102 } 1103 } 1104 } 1105 } 1106 1107 return (0); 1108 } 1109 1110 /*- 1111 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1112 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1113 * this bit is not defined for FAT12 volumes, which are always assumed to 1114 * be clean. 1115 * 1116 * The fatentry() routine only works on cluster numbers that a file could 1117 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1118 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1119 * 1120 * Inputs: 1121 * pmp The MS-DOS volume to mark 1122 * dirty Non-zero if the volume should be marked dirty; zero if it 1123 * should be marked clean 1124 * 1125 * Result: 1126 * 0 Success 1127 * EROFS Volume is read-only 1128 * ? (other errors from called routines) 1129 */ 1130 int 1131 markvoldirty(struct msdosfsmount *pmp, int dirty) 1132 { 1133 struct buf *bp; 1134 u_long bn, bo, bsize, byteoffset, fatval; 1135 int error; 1136 1137 /* 1138 * FAT12 does not support a "clean" bit, so don't do anything for 1139 * FAT12. 1140 */ 1141 if (FAT12(pmp)) 1142 return (0); 1143 1144 /* Can't change the bit on a read-only filesystem. */ 1145 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1146 return (EROFS); 1147 1148 /* 1149 * Fetch the block containing the FAT entry. It is given by the 1150 * pseudo-cluster 1. 1151 */ 1152 byteoffset = FATOFS(pmp, 1); 1153 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1154 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1155 if (error) { 1156 brelse(bp); 1157 return (error); 1158 } 1159 1160 /* 1161 * Get the current value of the FAT entry and set/clear the relevant 1162 * bit. Dirty means clear the "clean" bit; clean means set the 1163 * "clean" bit. 1164 */ 1165 if (FAT32(pmp)) { 1166 /* FAT32 uses bit 27. */ 1167 fatval = getulong(&bp->b_data[bo]); 1168 if (dirty) 1169 fatval &= 0xF7FFFFFF; 1170 else 1171 fatval |= 0x08000000; 1172 putulong(&bp->b_data[bo], fatval); 1173 } else { 1174 /* Must be FAT16; use bit 15. */ 1175 fatval = getushort(&bp->b_data[bo]); 1176 if (dirty) 1177 fatval &= 0x7FFF; 1178 else 1179 fatval |= 0x8000; 1180 putushort(&bp->b_data[bo], fatval); 1181 } 1182 1183 /* Write out the modified FAT block synchronously. */ 1184 return (bwrite(bp)); 1185 }
Cache object: db58d0151d28e1b1056e4e8fbfe80549
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]