msdosfs_fat.c revision 308550
1/* $FreeBSD: stable/10/sys/fs/msdosfs/msdosfs_fat.c 308550 2016-11-11 20:04:19Z kib $ */ 2/* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 ws Exp $ */ 3 4/*- 5 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank. 6 * Copyright (C) 1994, 1995, 1997 TooLs GmbH. 7 * All rights reserved. 8 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below). 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by TooLs GmbH. 21 * 4. The name of TooLs GmbH may not be used to endorse or promote products 22 * derived from this software without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 29 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 30 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 31 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 32 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 33 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35/*- 36 * Written by Paul Popelka (paulp@uts.amdahl.com) 37 * 38 * You can do anything you want with this software, just don't say you wrote 39 * it, and don't remove this notice. 40 * 41 * This software is provided "as is". 42 * 43 * The author supplies this software to be publicly redistributed on the 44 * understanding that the author is not responsible for the correct 45 * functioning of this software in any circumstances and is not liable for 46 * any damages caused by this software. 47 * 48 * October 1992 49 */ 50 51#include <sys/param.h> 52#include <sys/systm.h> 53#include <sys/buf.h> 54#include <sys/mount.h> 55#include <sys/vnode.h> 56 57#include <fs/msdosfs/bpb.h> 58#include <fs/msdosfs/direntry.h> 59#include <fs/msdosfs/denode.h> 60#include <fs/msdosfs/fat.h> 61#include <fs/msdosfs/msdosfsmount.h> 62 63#define FULL_RUN ((u_int)0xffffffff) 64 65static int chainalloc(struct msdosfsmount *pmp, u_long start, 66 u_long count, u_long fillwith, u_long *retcluster, 67 u_long *got); 68static int chainlength(struct msdosfsmount *pmp, u_long start, 69 u_long count); 70static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 71 u_long *sizep, u_long *bop); 72static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 73 u_long fillwith); 74static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 75 u_long *fsrcnp); 76static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 77 u_long fatbn); 78static __inline void 79 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 80static __inline void 81 usemap_free(struct msdosfsmount *pmp, u_long cn); 82static int clusteralloc1(struct msdosfsmount *pmp, u_long start, 83 u_long count, u_long fillwith, u_long *retcluster, 84 u_long *got); 85 86static void 87fatblock(pmp, ofs, bnp, sizep, bop) 88 struct msdosfsmount *pmp; 89 u_long ofs; 90 u_long *bnp; 91 u_long *sizep; 92 u_long *bop; 93{ 94 u_long bn, size; 95 96 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 97 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 98 * DEV_BSIZE; 99 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 100 101 if (bnp) 102 *bnp = bn; 103 if (sizep) 104 *sizep = size; 105 if (bop) 106 *bop = ofs % pmp->pm_fatblocksize; 107} 108 109/* 110 * Map the logical cluster number of a file into a physical disk sector 111 * that is filesystem relative. 112 * 113 * dep - address of denode representing the file of interest 114 * findcn - file relative cluster whose filesystem relative cluster number 115 * and/or block number are/is to be found 116 * bnp - address of where to place the filesystem relative block number. 117 * If this pointer is null then don't return this quantity. 118 * cnp - address of where to place the filesystem relative cluster number. 119 * If this pointer is null then don't return this quantity. 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 */ 127int 128pcbmap(dep, findcn, bnp, cnp, sp) 129 struct denode *dep; 130 u_long findcn; /* file relative cluster to get */ 131 daddr_t *bnp; /* returned filesys relative blk number */ 132 u_long *cnp; /* returned cluster number */ 133 int *sp; /* returned block size */ 134{ 135 int error; 136 u_long i; 137 u_long cn; 138 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 139 u_long byteoffset; 140 u_long bn; 141 u_long bo; 142 struct buf *bp = NULL; 143 u_long bp_bn = -1; 144 struct msdosfsmount *pmp = dep->de_pmp; 145 u_long bsize; 146 147 KASSERT(bnp != NULL || cnp != NULL || sp != NULL, 148 ("pcbmap: extra call")); 149 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap"); 150 151 cn = dep->de_StartCluster; 152 /* 153 * The "file" that makes up the root directory is contiguous, 154 * permanently allocated, of fixed size, and is not made up of 155 * clusters. If the cluster number is beyond the end of the root 156 * directory, then return the number of clusters in the file. 157 */ 158 if (cn == MSDOSFSROOT) { 159 if (dep->de_Attributes & ATTR_DIRECTORY) { 160 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 161 if (cnp) 162 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 163 return (E2BIG); 164 } 165 if (bnp) 166 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 167 if (cnp) 168 *cnp = MSDOSFSROOT; 169 if (sp) 170 *sp = min(pmp->pm_bpcluster, 171 dep->de_FileSize - de_cn2off(pmp, findcn)); 172 return (0); 173 } else { /* just an empty file */ 174 if (cnp) 175 *cnp = 0; 176 return (E2BIG); 177 } 178 } 179 180 /* 181 * All other files do I/O in cluster sized blocks 182 */ 183 if (sp) 184 *sp = pmp->pm_bpcluster; 185 186 /* 187 * Rummage around in the fat cache, maybe we can avoid tromping 188 * thru every fat entry for the file. And, keep track of how far 189 * off the cache was from where we wanted to be. 190 */ 191 i = 0; 192 fc_lookup(dep, findcn, &i, &cn); 193 194 /* 195 * Handle all other files or directories the normal way. 196 */ 197 for (; i < findcn; i++) { 198 /* 199 * Stop with all reserved clusters, not just with EOF. 200 */ 201 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 202 goto hiteof; 203 byteoffset = FATOFS(pmp, cn); 204 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 205 if (bn != bp_bn) { 206 if (bp) 207 brelse(bp); 208 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 209 if (error) { 210 brelse(bp); 211 return (error); 212 } 213 bp_bn = bn; 214 } 215 prevcn = cn; 216 if (bo >= bsize) { 217 if (bp) 218 brelse(bp); 219 return (EIO); 220 } 221 if (FAT32(pmp)) 222 cn = getulong(&bp->b_data[bo]); 223 else 224 cn = getushort(&bp->b_data[bo]); 225 if (FAT12(pmp) && (prevcn & 1)) 226 cn >>= 4; 227 cn &= pmp->pm_fatmask; 228 229 /* 230 * Force the special cluster numbers 231 * to be the same for all cluster sizes 232 * to let the rest of msdosfs handle 233 * all cases the same. 234 */ 235 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 236 cn |= ~pmp->pm_fatmask; 237 } 238 239 if (!MSDOSFSEOF(pmp, cn)) { 240 if (bp) 241 brelse(bp); 242 if (bnp) 243 *bnp = cntobn(pmp, cn); 244 if (cnp) 245 *cnp = cn; 246 fc_setcache(dep, FC_LASTMAP, i, cn); 247 return (0); 248 } 249 250hiteof:; 251 if (cnp) 252 *cnp = i; 253 if (bp) 254 brelse(bp); 255 /* update last file cluster entry in the fat cache */ 256 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 257 return (E2BIG); 258} 259 260/* 261 * Find the closest entry in the fat cache to the cluster we are looking 262 * for. 263 */ 264static void 265fc_lookup(dep, findcn, frcnp, fsrcnp) 266 struct denode *dep; 267 u_long findcn; 268 u_long *frcnp; 269 u_long *fsrcnp; 270{ 271 int i; 272 u_long cn; 273 struct fatcache *closest = 0; 274 275 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup"); 276 277 for (i = 0; i < FC_SIZE; i++) { 278 cn = dep->de_fc[i].fc_frcn; 279 if (cn != FCE_EMPTY && cn <= findcn) { 280 if (closest == 0 || cn > closest->fc_frcn) 281 closest = &dep->de_fc[i]; 282 } 283 } 284 if (closest) { 285 *frcnp = closest->fc_frcn; 286 *fsrcnp = closest->fc_fsrcn; 287 } 288} 289 290/* 291 * Purge the fat cache in denode dep of all entries relating to file 292 * relative cluster frcn and beyond. 293 */ 294void 295fc_purge(dep, frcn) 296 struct denode *dep; 297 u_int frcn; 298{ 299 int i; 300 struct fatcache *fcp; 301 302 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge"); 303 304 fcp = dep->de_fc; 305 for (i = 0; i < FC_SIZE; i++, fcp++) { 306 if (fcp->fc_frcn >= frcn) 307 fcp->fc_frcn = FCE_EMPTY; 308 } 309} 310 311/* 312 * Update the fat. 313 * If mirroring the fat, update all copies, with the first copy as last. 314 * Else update only the current fat (ignoring the others). 315 * 316 * pmp - msdosfsmount structure for filesystem to update 317 * bp - addr of modified fat block 318 * fatbn - block number relative to begin of filesystem of the modified fat block. 319 */ 320static void 321updatefats(pmp, bp, fatbn) 322 struct msdosfsmount *pmp; 323 struct buf *bp; 324 u_long fatbn; 325{ 326 struct buf *bpn; 327 int cleanfat, i; 328 329#ifdef MSDOSFS_DEBUG 330 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 331#endif 332 333 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 334 /* 335 * Now copy the block(s) of the modified fat to the other copies of 336 * the fat and write them out. This is faster than reading in the 337 * other fats and then writing them back out. This could tie up 338 * the fat for quite a while. Preventing others from accessing it. 339 * To prevent us from going after the fat quite so much we use 340 * delayed writes, unless they specfied "synchronous" when the 341 * filesystem was mounted. If synch is asked for then use 342 * bwrite()'s and really slow things down. 343 */ 344 if (fatbn != pmp->pm_fatblk || FAT12(pmp)) 345 cleanfat = 0; 346 else if (FAT16(pmp)) 347 cleanfat = 16; 348 else 349 cleanfat = 32; 350 for (i = 1; i < pmp->pm_FATs; i++) { 351 fatbn += pmp->pm_FATsecs; 352 /* getblk() never fails */ 353 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 354 0, 0, 0); 355 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 356 /* Force the clean bit on in the other copies. */ 357 if (cleanfat == 16) 358 ((u_int8_t *)bpn->b_data)[3] |= 0x80; 359 else if (cleanfat == 32) 360 ((u_int8_t *)bpn->b_data)[7] |= 0x08; 361 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 362 bwrite(bpn); 363 else 364 bdwrite(bpn); 365 } 366 } 367 368 /* 369 * Write out the first (or current) fat last. 370 */ 371 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 372 bwrite(bp); 373 else 374 bdwrite(bp); 375} 376 377/* 378 * Updating entries in 12 bit fats is a pain in the butt. 379 * 380 * The following picture shows where nibbles go when moving from a 12 bit 381 * cluster number into the appropriate bytes in the FAT. 382 * 383 * byte m byte m+1 byte m+2 384 * +----+----+ +----+----+ +----+----+ 385 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 386 * +----+----+ +----+----+ +----+----+ 387 * 388 * +----+----+----+ +----+----+----+ 389 * | 3 0 1 | | 4 5 2 | 390 * +----+----+----+ +----+----+----+ 391 * cluster n cluster n+1 392 * 393 * Where n is even. m = n + (n >> 2) 394 * 395 */ 396static __inline void 397usemap_alloc(pmp, cn) 398 struct msdosfsmount *pmp; 399 u_long cn; 400{ 401 402 MSDOSFS_ASSERT_MP_LOCKED(pmp); 403 404 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 405 ("usemap_alloc on ro msdosfs mount")); 406 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 407 == 0, ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS, 408 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 409 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 410 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little")); 411 pmp->pm_freeclustercount--; 412 pmp->pm_flags |= MSDOSFS_FSIMOD; 413} 414 415static __inline void 416usemap_free(pmp, cn) 417 struct msdosfsmount *pmp; 418 u_long cn; 419{ 420 421 MSDOSFS_ASSERT_MP_LOCKED(pmp); 422 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 423 ("usemap_free on ro msdosfs mount")); 424 pmp->pm_freeclustercount++; 425 pmp->pm_flags |= MSDOSFS_FSIMOD; 426 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 427 != 0, ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS, 428 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 429 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 430} 431 432int 433clusterfree(pmp, cluster, oldcnp) 434 struct msdosfsmount *pmp; 435 u_long cluster; 436 u_long *oldcnp; 437{ 438 int error; 439 u_long oldcn; 440 441 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 442 if (error) 443 return (error); 444 /* 445 * If the cluster was successfully marked free, then update 446 * the count of free clusters, and turn off the "allocated" 447 * bit in the "in use" cluster bit map. 448 */ 449 MSDOSFS_LOCK_MP(pmp); 450 usemap_free(pmp, cluster); 451 MSDOSFS_UNLOCK_MP(pmp); 452 if (oldcnp) 453 *oldcnp = oldcn; 454 return (0); 455} 456 457/* 458 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 459 * 460 * function - whether to get or set a fat entry 461 * pmp - address of the msdosfsmount structure for the filesystem 462 * whose fat is to be manipulated. 463 * cn - which cluster is of interest 464 * oldcontents - address of a word that is to receive the contents of the 465 * cluster'th entry if this is a get function 466 * newcontents - the new value to be written into the cluster'th element of 467 * the fat if this is a set function. 468 * 469 * This function can also be used to free a cluster by setting the fat entry 470 * for a cluster to 0. 471 * 472 * All copies of the fat are updated if this is a set function. NOTE: If 473 * fatentry() marks a cluster as free it does not update the inusemap in 474 * the msdosfsmount structure. This is left to the caller. 475 */ 476int 477fatentry(function, pmp, cn, oldcontents, newcontents) 478 int function; 479 struct msdosfsmount *pmp; 480 u_long cn; 481 u_long *oldcontents; 482 u_long newcontents; 483{ 484 int error; 485 u_long readcn; 486 u_long bn, bo, bsize, byteoffset; 487 struct buf *bp; 488 489#ifdef MSDOSFS_DEBUG 490 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 491 function, pmp, cn, oldcontents, newcontents); 492#endif 493 494#ifdef DIAGNOSTIC 495 /* 496 * Be sure they asked us to do something. 497 */ 498 if ((function & (FAT_SET | FAT_GET)) == 0) { 499#ifdef MSDOSFS_DEBUG 500 printf("fatentry(): function code doesn't specify get or set\n"); 501#endif 502 return (EINVAL); 503 } 504 505 /* 506 * If they asked us to return a cluster number but didn't tell us 507 * where to put it, give them an error. 508 */ 509 if ((function & FAT_GET) && oldcontents == NULL) { 510#ifdef MSDOSFS_DEBUG 511 printf("fatentry(): get function with no place to put result\n"); 512#endif 513 return (EINVAL); 514 } 515#endif 516 517 /* 518 * Be sure the requested cluster is in the filesystem. 519 */ 520 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 521 return (EINVAL); 522 523 byteoffset = FATOFS(pmp, cn); 524 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 525 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 526 if (error) { 527 brelse(bp); 528 return (error); 529 } 530 531 if (function & FAT_GET) { 532 if (FAT32(pmp)) 533 readcn = getulong(&bp->b_data[bo]); 534 else 535 readcn = getushort(&bp->b_data[bo]); 536 if (FAT12(pmp) & (cn & 1)) 537 readcn >>= 4; 538 readcn &= pmp->pm_fatmask; 539 /* map reserved fat entries to same values for all fats */ 540 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 541 readcn |= ~pmp->pm_fatmask; 542 *oldcontents = readcn; 543 } 544 if (function & FAT_SET) { 545 switch (pmp->pm_fatmask) { 546 case FAT12_MASK: 547 readcn = getushort(&bp->b_data[bo]); 548 if (cn & 1) { 549 readcn &= 0x000f; 550 readcn |= newcontents << 4; 551 } else { 552 readcn &= 0xf000; 553 readcn |= newcontents & 0xfff; 554 } 555 putushort(&bp->b_data[bo], readcn); 556 break; 557 case FAT16_MASK: 558 putushort(&bp->b_data[bo], newcontents); 559 break; 560 case FAT32_MASK: 561 /* 562 * According to spec we have to retain the 563 * high order bits of the fat entry. 564 */ 565 readcn = getulong(&bp->b_data[bo]); 566 readcn &= ~FAT32_MASK; 567 readcn |= newcontents & FAT32_MASK; 568 putulong(&bp->b_data[bo], readcn); 569 break; 570 } 571 updatefats(pmp, bp, bn); 572 bp = NULL; 573 pmp->pm_fmod = 1; 574 } 575 if (bp) 576 brelse(bp); 577 return (0); 578} 579 580/* 581 * Update a contiguous cluster chain 582 * 583 * pmp - mount point 584 * start - first cluster of chain 585 * count - number of clusters in chain 586 * fillwith - what to write into fat entry of last cluster 587 */ 588static int 589fatchain(pmp, start, count, fillwith) 590 struct msdosfsmount *pmp; 591 u_long start; 592 u_long count; 593 u_long fillwith; 594{ 595 int error; 596 u_long bn, bo, bsize, byteoffset, readcn, newc; 597 struct buf *bp; 598 599#ifdef MSDOSFS_DEBUG 600 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 601 pmp, start, count, fillwith); 602#endif 603 /* 604 * Be sure the clusters are in the filesystem. 605 */ 606 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 607 return (EINVAL); 608 609 while (count > 0) { 610 byteoffset = FATOFS(pmp, start); 611 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 612 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 613 if (error) { 614 brelse(bp); 615 return (error); 616 } 617 while (count > 0) { 618 start++; 619 newc = --count > 0 ? start : fillwith; 620 switch (pmp->pm_fatmask) { 621 case FAT12_MASK: 622 readcn = getushort(&bp->b_data[bo]); 623 if (start & 1) { 624 readcn &= 0xf000; 625 readcn |= newc & 0xfff; 626 } else { 627 readcn &= 0x000f; 628 readcn |= newc << 4; 629 } 630 putushort(&bp->b_data[bo], readcn); 631 bo++; 632 if (!(start & 1)) 633 bo++; 634 break; 635 case FAT16_MASK: 636 putushort(&bp->b_data[bo], newc); 637 bo += 2; 638 break; 639 case FAT32_MASK: 640 readcn = getulong(&bp->b_data[bo]); 641 readcn &= ~pmp->pm_fatmask; 642 readcn |= newc & pmp->pm_fatmask; 643 putulong(&bp->b_data[bo], readcn); 644 bo += 4; 645 break; 646 } 647 if (bo >= bsize) 648 break; 649 } 650 updatefats(pmp, bp, bn); 651 } 652 pmp->pm_fmod = 1; 653 return (0); 654} 655 656/* 657 * Check the length of a free cluster chain starting at start. 658 * 659 * pmp - mount point 660 * start - start of chain 661 * count - maximum interesting length 662 */ 663static int 664chainlength(pmp, start, count) 665 struct msdosfsmount *pmp; 666 u_long start; 667 u_long count; 668{ 669 u_long idx, max_idx; 670 u_int map; 671 u_long len; 672 673 MSDOSFS_ASSERT_MP_LOCKED(pmp); 674 675 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 676 idx = start / N_INUSEBITS; 677 start %= N_INUSEBITS; 678 map = pmp->pm_inusemap[idx]; 679 map &= ~((1 << start) - 1); 680 if (map) { 681 len = ffs(map) - 1 - start; 682 return (len > count ? count : len); 683 } 684 len = N_INUSEBITS - start; 685 if (len >= count) 686 return (count); 687 while (++idx <= max_idx) { 688 if (len >= count) 689 break; 690 map = pmp->pm_inusemap[idx]; 691 if (map) { 692 len += ffs(map) - 1; 693 break; 694 } 695 len += N_INUSEBITS; 696 } 697 return (len > count ? count : len); 698} 699 700/* 701 * Allocate contigous free clusters. 702 * 703 * pmp - mount point. 704 * start - start of cluster chain. 705 * count - number of clusters to allocate. 706 * fillwith - put this value into the fat entry for the 707 * last allocated cluster. 708 * retcluster - put the first allocated cluster's number here. 709 * got - how many clusters were actually allocated. 710 */ 711static int 712chainalloc(pmp, start, count, fillwith, retcluster, got) 713 struct msdosfsmount *pmp; 714 u_long start; 715 u_long count; 716 u_long fillwith; 717 u_long *retcluster; 718 u_long *got; 719{ 720 int error; 721 u_long cl, n; 722 723 MSDOSFS_ASSERT_MP_LOCKED(pmp); 724 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 725 ("chainalloc on ro msdosfs mount")); 726 727 for (cl = start, n = count; n-- > 0;) 728 usemap_alloc(pmp, cl++); 729 pmp->pm_nxtfree = start + count; 730 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 731 pmp->pm_nxtfree = CLUST_FIRST; 732 pmp->pm_flags |= MSDOSFS_FSIMOD; 733 error = fatchain(pmp, start, count, fillwith); 734 if (error != 0) { 735 for (cl = start, n = count; n-- > 0;) 736 usemap_free(pmp, cl++); 737 return (error); 738 } 739#ifdef MSDOSFS_DEBUG 740 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 741 start, count); 742#endif 743 if (retcluster) 744 *retcluster = start; 745 if (got) 746 *got = count; 747 return (0); 748} 749 750/* 751 * Allocate contiguous free clusters. 752 * 753 * pmp - mount point. 754 * start - preferred start of cluster chain. 755 * count - number of clusters requested. 756 * fillwith - put this value into the fat entry for the 757 * last allocated cluster. 758 * retcluster - put the first allocated cluster's number here. 759 * got - how many clusters were actually allocated. 760 */ 761int 762clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 763 u_long fillwith, u_long *retcluster, u_long *got) 764{ 765 int error; 766 767 MSDOSFS_LOCK_MP(pmp); 768 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 769 MSDOSFS_UNLOCK_MP(pmp); 770 return (error); 771} 772 773static int 774clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 775 u_long fillwith, u_long *retcluster, u_long *got) 776{ 777 u_long idx; 778 u_long len, newst, foundl, cn, l; 779 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 780 u_int map; 781 782 MSDOSFS_ASSERT_MP_LOCKED(pmp); 783 784#ifdef MSDOSFS_DEBUG 785 printf("clusteralloc(): find %lu clusters\n", count); 786#endif 787 if (start) { 788 if ((len = chainlength(pmp, start, count)) >= count) 789 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 790 } else 791 len = 0; 792 793 newst = pmp->pm_nxtfree; 794 foundl = 0; 795 796 for (cn = newst; cn <= pmp->pm_maxcluster;) { 797 idx = cn / N_INUSEBITS; 798 map = pmp->pm_inusemap[idx]; 799 map |= (1 << (cn % N_INUSEBITS)) - 1; 800 if (map != FULL_RUN) { 801 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 802 if ((l = chainlength(pmp, cn, count)) >= count) 803 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 804 if (l > foundl) { 805 foundcn = cn; 806 foundl = l; 807 } 808 cn += l + 1; 809 continue; 810 } 811 cn += N_INUSEBITS - cn % N_INUSEBITS; 812 } 813 for (cn = 0; cn < newst;) { 814 idx = cn / N_INUSEBITS; 815 map = pmp->pm_inusemap[idx]; 816 map |= (1 << (cn % N_INUSEBITS)) - 1; 817 if (map != FULL_RUN) { 818 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 819 if ((l = chainlength(pmp, cn, count)) >= count) 820 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 821 if (l > foundl) { 822 foundcn = cn; 823 foundl = l; 824 } 825 cn += l + 1; 826 continue; 827 } 828 cn += N_INUSEBITS - cn % N_INUSEBITS; 829 } 830 831 if (!foundl) 832 return (ENOSPC); 833 834 if (len) 835 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 836 else 837 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 838} 839 840 841/* 842 * Free a chain of clusters. 843 * 844 * pmp - address of the msdosfs mount structure for the filesystem 845 * containing the cluster chain to be freed. 846 * startcluster - number of the 1st cluster in the chain of clusters to be 847 * freed. 848 */ 849int 850freeclusterchain(pmp, cluster) 851 struct msdosfsmount *pmp; 852 u_long cluster; 853{ 854 int error; 855 struct buf *bp = NULL; 856 u_long bn, bo, bsize, byteoffset; 857 u_long readcn, lbn = -1; 858 859 MSDOSFS_LOCK_MP(pmp); 860 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 861 byteoffset = FATOFS(pmp, cluster); 862 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 863 if (lbn != bn) { 864 if (bp) 865 updatefats(pmp, bp, lbn); 866 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 867 if (error) { 868 brelse(bp); 869 MSDOSFS_UNLOCK_MP(pmp); 870 return (error); 871 } 872 lbn = bn; 873 } 874 usemap_free(pmp, cluster); 875 switch (pmp->pm_fatmask) { 876 case FAT12_MASK: 877 readcn = getushort(&bp->b_data[bo]); 878 if (cluster & 1) { 879 cluster = readcn >> 4; 880 readcn &= 0x000f; 881 readcn |= MSDOSFSFREE << 4; 882 } else { 883 cluster = readcn; 884 readcn &= 0xf000; 885 readcn |= MSDOSFSFREE & 0xfff; 886 } 887 putushort(&bp->b_data[bo], readcn); 888 break; 889 case FAT16_MASK: 890 cluster = getushort(&bp->b_data[bo]); 891 putushort(&bp->b_data[bo], MSDOSFSFREE); 892 break; 893 case FAT32_MASK: 894 cluster = getulong(&bp->b_data[bo]); 895 putulong(&bp->b_data[bo], 896 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 897 break; 898 } 899 cluster &= pmp->pm_fatmask; 900 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 901 cluster |= pmp->pm_fatmask; 902 } 903 if (bp) 904 updatefats(pmp, bp, bn); 905 MSDOSFS_UNLOCK_MP(pmp); 906 return (0); 907} 908 909/* 910 * Read in fat blocks looking for free clusters. For every free cluster 911 * found turn off its corresponding bit in the pm_inusemap. 912 */ 913int 914fillinusemap(pmp) 915 struct msdosfsmount *pmp; 916{ 917 struct buf *bp = NULL; 918 u_long cn, readcn; 919 int error; 920 u_long bn, bo, bsize, byteoffset; 921 922 MSDOSFS_ASSERT_MP_LOCKED(pmp); 923 924 /* 925 * Mark all clusters in use, we mark the free ones in the fat scan 926 * loop further down. 927 */ 928 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 929 pmp->pm_inusemap[cn] = FULL_RUN; 930 931 /* 932 * Figure how many free clusters are in the filesystem by ripping 933 * through the fat counting the number of entries whose content is 934 * zero. These represent free clusters. 935 */ 936 pmp->pm_freeclustercount = 0; 937 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 938 byteoffset = FATOFS(pmp, cn); 939 bo = byteoffset % pmp->pm_fatblocksize; 940 if (!bo || !bp) { 941 /* Read new FAT block */ 942 if (bp) 943 brelse(bp); 944 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 945 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 946 if (error) { 947 brelse(bp); 948 return (error); 949 } 950 } 951 if (FAT32(pmp)) 952 readcn = getulong(&bp->b_data[bo]); 953 else 954 readcn = getushort(&bp->b_data[bo]); 955 if (FAT12(pmp) && (cn & 1)) 956 readcn >>= 4; 957 readcn &= pmp->pm_fatmask; 958 959 if (readcn == CLUST_FREE) 960 usemap_free(pmp, cn); 961 } 962 if (bp != NULL) 963 brelse(bp); 964 return (0); 965} 966 967/* 968 * Allocate a new cluster and chain it onto the end of the file. 969 * 970 * dep - the file to extend 971 * count - number of clusters to allocate 972 * bpp - where to return the address of the buf header for the first new 973 * file block 974 * ncp - where to put cluster number of the first newly allocated cluster 975 * If this pointer is 0, do not return the cluster number. 976 * flags - see fat.h 977 * 978 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 979 * the de_flag field of the denode and it does not change the de_FileSize 980 * field. This is left for the caller to do. 981 */ 982int 983extendfile(dep, count, bpp, ncp, flags) 984 struct denode *dep; 985 u_long count; 986 struct buf **bpp; 987 u_long *ncp; 988 int flags; 989{ 990 int error; 991 u_long frcn; 992 u_long cn, got; 993 struct msdosfsmount *pmp = dep->de_pmp; 994 struct buf *bp; 995 daddr_t blkno; 996 997 /* 998 * Don't try to extend the root directory 999 */ 1000 if (dep->de_StartCluster == MSDOSFSROOT 1001 && (dep->de_Attributes & ATTR_DIRECTORY)) { 1002#ifdef MSDOSFS_DEBUG 1003 printf("extendfile(): attempt to extend root directory\n"); 1004#endif 1005 return (ENOSPC); 1006 } 1007 1008 /* 1009 * If the "file's last cluster" cache entry is empty, and the file 1010 * is not empty, then fill the cache entry by calling pcbmap(). 1011 */ 1012 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 1013 dep->de_StartCluster != 0) { 1014 error = pcbmap(dep, 0xffff, 0, &cn, 0); 1015 /* we expect it to return E2BIG */ 1016 if (error != E2BIG) 1017 return (error); 1018 } 1019 1020 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 1021 dep->de_fc[FC_LASTFC].fc_frcn; 1022 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 1023 dep->de_fc[FC_LASTFC].fc_fsrcn; 1024 while (count > 0) { 1025 /* 1026 * Allocate a new cluster chain and cat onto the end of the 1027 * file. 1028 * If the file is empty we make de_StartCluster point 1029 * to the new block. Note that de_StartCluster being 1030 * 0 is sufficient to be sure the file is empty since 1031 * we exclude attempts to extend the root directory 1032 * above, and the root dir is the only file with a 1033 * startcluster of 0 that has blocks allocated (sort 1034 * of). 1035 */ 1036 if (dep->de_StartCluster == 0) 1037 cn = 0; 1038 else 1039 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1040 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1041 if (error) 1042 return (error); 1043 1044 count -= got; 1045 1046 /* 1047 * Give them the filesystem relative cluster number if they want 1048 * it. 1049 */ 1050 if (ncp) { 1051 *ncp = cn; 1052 ncp = NULL; 1053 } 1054 1055 if (dep->de_StartCluster == 0) { 1056 dep->de_StartCluster = cn; 1057 frcn = 0; 1058 } else { 1059 error = fatentry(FAT_SET, pmp, 1060 dep->de_fc[FC_LASTFC].fc_fsrcn, 1061 0, cn); 1062 if (error) { 1063 clusterfree(pmp, cn, NULL); 1064 return (error); 1065 } 1066 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1067 } 1068 1069 /* 1070 * Update the "last cluster of the file" entry in the denode's fat 1071 * cache. 1072 */ 1073 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1074 1075 if (flags & DE_CLEAR) { 1076 while (got-- > 0) { 1077 /* 1078 * Get the buf header for the new block of the file. 1079 */ 1080 if (dep->de_Attributes & ATTR_DIRECTORY) 1081 bp = getblk(pmp->pm_devvp, 1082 cntobn(pmp, cn++), 1083 pmp->pm_bpcluster, 0, 0, 0); 1084 else { 1085 bp = getblk(DETOV(dep), 1086 frcn++, 1087 pmp->pm_bpcluster, 0, 0, 0); 1088 /* 1089 * Do the bmap now, as in msdosfs_write 1090 */ 1091 if (pcbmap(dep, 1092 bp->b_lblkno, 1093 &blkno, 0, 0)) 1094 bp->b_blkno = -1; 1095 if (bp->b_blkno == -1) 1096 panic("extendfile: pcbmap"); 1097 else 1098 bp->b_blkno = blkno; 1099 } 1100 vfs_bio_clrbuf(bp); 1101 if (bpp) { 1102 *bpp = bp; 1103 bpp = NULL; 1104 } else 1105 bdwrite(bp); 1106 } 1107 } 1108 } 1109 1110 return (0); 1111} 1112 1113/*- 1114 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1115 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1116 * this bit is not defined for FAT12 volumes, which are always assumed to 1117 * be clean. 1118 * 1119 * The fatentry() routine only works on cluster numbers that a file could 1120 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1121 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1122 * 1123 * Inputs: 1124 * pmp The MS-DOS volume to mark 1125 * dirty Non-zero if the volume should be marked dirty; zero if it 1126 * should be marked clean 1127 * 1128 * Result: 1129 * 0 Success 1130 * EROFS Volume is read-only 1131 * ? (other errors from called routines) 1132 */ 1133int 1134markvoldirty(struct msdosfsmount *pmp, int dirty) 1135{ 1136 struct buf *bp; 1137 u_long bn, bo, bsize, byteoffset, fatval; 1138 int error; 1139 1140 /* 1141 * FAT12 does not support a "clean" bit, so don't do anything for 1142 * FAT12. 1143 */ 1144 if (FAT12(pmp)) 1145 return (0); 1146 1147 /* Can't change the bit on a read-only filesystem. */ 1148 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1149 return (EROFS); 1150 1151 /* 1152 * Fetch the block containing the FAT entry. It is given by the 1153 * pseudo-cluster 1. 1154 */ 1155 byteoffset = FATOFS(pmp, 1); 1156 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1157 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1158 if (error) { 1159 brelse(bp); 1160 return (error); 1161 } 1162 1163 /* 1164 * Get the current value of the FAT entry and set/clear the relevant 1165 * bit. Dirty means clear the "clean" bit; clean means set the 1166 * "clean" bit. 1167 */ 1168 if (FAT32(pmp)) { 1169 /* FAT32 uses bit 27. */ 1170 fatval = getulong(&bp->b_data[bo]); 1171 if (dirty) 1172 fatval &= 0xF7FFFFFF; 1173 else 1174 fatval |= 0x08000000; 1175 putulong(&bp->b_data[bo], fatval); 1176 } else { 1177 /* Must be FAT16; use bit 15. */ 1178 fatval = getushort(&bp->b_data[bo]); 1179 if (dirty) 1180 fatval &= 0x7FFF; 1181 else 1182 fatval |= 0x8000; 1183 putushort(&bp->b_data[bo], fatval); 1184 } 1185 1186 /* Write out the modified FAT block synchronously. */ 1187 return (bwrite(bp)); 1188} 1189