1/* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 ws Exp $ */ 2 3/*- 4 * SPDX-License-Identifier: BSD-4-Clause 5 * 6 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank. 7 * Copyright (C) 1994, 1995, 1997 TooLs GmbH. 8 * All rights reserved. 9 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below). 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by TooLs GmbH. 22 * 4. The name of TooLs GmbH may not be used to endorse or promote products 23 * derived from this software without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR 26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 28 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 29 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 30 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 31 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 32 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 33 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 34 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 35 */ 36/*- 37 * Written by Paul Popelka (paulp@uts.amdahl.com) 38 * 39 * You can do anything you want with this software, just don't say you wrote 40 * it, and don't remove this notice. 41 * 42 * This software is provided "as is". 43 * 44 * The author supplies this software to be publicly redistributed on the 45 * understanding that the author is not responsible for the correct 46 * functioning of this software in any circumstances and is not liable for 47 * any damages caused by this software. 48 * 49 * October 1992 50 */ 51 52#include <sys/param.h> 53#include <sys/systm.h> 54#include <sys/buf.h> 55#include <sys/mount.h> 56#include <sys/vmmeter.h> 57#include <sys/vnode.h> 58 59#include <fs/msdosfs/bpb.h> 60#include <fs/msdosfs/direntry.h> 61#include <fs/msdosfs/denode.h> 62#include <fs/msdosfs/fat.h> 63#include <fs/msdosfs/msdosfsmount.h> 64 65#define FULL_RUN ((u_int)0xffffffff) 66 67static int chainalloc(struct msdosfsmount *pmp, u_long start, 68 u_long count, u_long fillwith, u_long *retcluster, 69 u_long *got); 70static int chainlength(struct msdosfsmount *pmp, u_long start, 71 u_long count); 72static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 73 u_long *sizep, u_long *bop); 74static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 75 u_long fillwith); 76static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 77 u_long *fsrcnp); 78static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 79 u_long fatbn); 80static __inline void 81 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 82static int usemap_free(struct msdosfsmount *pmp, u_long cn); 83static int clusteralloc1(struct msdosfsmount *pmp, u_long start, 84 u_long count, u_long fillwith, u_long *retcluster, 85 u_long *got); 86 87static void 88fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep, 89 u_long *bop) 90{ 91 u_long bn, size, fatblocksec; 92 93 fatblocksec = pmp->pm_fatblocksec; 94 if (FAT12(pmp) && fatblocksec % 3 != 0) { 95 fatblocksec *= 3; 96 if (fatblocksec % 6 == 0) 97 fatblocksec /= 2; 98 } 99 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 100 size = roundup(ulmin(fatblocksec, pmp->pm_FATsecs - bn) * DEV_BSIZE, 101 pmp->pm_BlkPerSec * DEV_BSIZE); 102 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 103 104 if (bnp) 105 *bnp = bn; 106 if (sizep) 107 *sizep = size; 108 if (bop) 109 *bop = ofs % pmp->pm_fatblocksize; 110} 111 112/* 113 * Map the logical cluster number of a file into a physical disk sector 114 * that is filesystem relative. 115 * 116 * dep - address of denode representing the file of interest 117 * findcn - file relative cluster whose filesystem relative cluster number 118 * and/or block number are/is to be found 119 * bnp - address of where to place the filesystem relative block number. 120 * If this pointer is null then don't return this quantity. 121 * cnp - address of where to place the filesystem relative cluster number. 122 * If this pointer is null then don't return this quantity. 123 * sp - pointer to returned block size 124 * 125 * NOTE: Either bnp or cnp must be non-null. 126 * This function has one side effect. If the requested file relative cluster 127 * is beyond the end of file, then the actual number of clusters in the file 128 * is returned in *cnp. This is useful for determining how long a directory is. 129 * If cnp is null, nothing is returned. 130 */ 131int 132pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp) 133{ 134 int error; 135 u_long i; 136 u_long cn; 137 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 138 u_long byteoffset; 139 u_long bn; 140 u_long bo; 141 struct buf *bp = NULL; 142 u_long bp_bn = -1; 143 struct msdosfsmount *pmp = dep->de_pmp; 144 u_long bsize; 145 146 KASSERT(bnp != NULL || cnp != NULL || sp != NULL, 147 ("pcbmap: extra call")); 148 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap"); 149 150 cn = dep->de_StartCluster; 151 /* 152 * The "file" that makes up the root directory is contiguous, 153 * permanently allocated, of fixed size, and is not made up of 154 * clusters. If the cluster number is beyond the end of the root 155 * directory, then return the number of clusters in the file. 156 */ 157 if (cn == MSDOSFSROOT) { 158 if (dep->de_Attributes & ATTR_DIRECTORY) { 159 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 160 if (cnp) 161 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 162 return (E2BIG); 163 } 164 if (bnp) 165 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 166 if (cnp) 167 *cnp = MSDOSFSROOT; 168 if (sp) 169 *sp = min(pmp->pm_bpcluster, 170 dep->de_FileSize - de_cn2off(pmp, findcn)); 171 return (0); 172 } else { /* just an empty file */ 173 if (cnp) 174 *cnp = 0; 175 return (E2BIG); 176 } 177 } 178 179 /* 180 * All other files do I/O in cluster sized blocks 181 */ 182 if (sp) 183 *sp = pmp->pm_bpcluster; 184 185 /* 186 * Rummage around in the FAT cache, maybe we can avoid tromping 187 * through every FAT entry for the file. And, keep track of how far 188 * off the cache was from where we wanted to be. 189 */ 190 i = 0; 191 fc_lookup(dep, findcn, &i, &cn); 192 193 /* 194 * Handle all other files or directories the normal way. 195 */ 196 for (; i < findcn; i++) { 197 /* 198 * Stop with all reserved clusters, not just with EOF. 199 */ 200 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 201 goto hiteof; 202 byteoffset = FATOFS(pmp, cn); 203 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 204 if (bn != bp_bn) { 205 if (bp) 206 brelse(bp); 207 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 208 if (error) { 209 return (error); 210 } 211 bp_bn = bn; 212 } 213 prevcn = cn; 214 if (bo >= bsize) { 215 if (bp) 216 brelse(bp); 217 return (EIO); 218 } 219 if (FAT32(pmp)) 220 cn = getulong(bp->b_data + bo); 221 else 222 cn = getushort(bp->b_data + bo); 223 if (FAT12(pmp) && (prevcn & 1)) 224 cn >>= 4; 225 cn &= pmp->pm_fatmask; 226 227 /* 228 * Force the special cluster numbers 229 * to be the same for all cluster sizes 230 * to let the rest of msdosfs handle 231 * all cases the same. 232 */ 233 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 234 cn |= ~pmp->pm_fatmask; 235 } 236 237 if (!MSDOSFSEOF(pmp, cn)) { 238 if (bp) 239 brelse(bp); 240 if (bnp) 241 *bnp = cntobn(pmp, cn); 242 if (cnp) 243 *cnp = cn; 244 fc_setcache(dep, FC_LASTMAP, i, cn); 245 return (0); 246 } 247 248hiteof:; 249 if (cnp) 250 *cnp = i; 251 if (bp) 252 brelse(bp); 253 /* update last file cluster entry in the FAT cache */ 254 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 255 return (E2BIG); 256} 257 258/* 259 * Find the closest entry in the FAT cache to the cluster we are looking 260 * for. 261 */ 262static void 263fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp) 264{ 265 int i; 266 u_long cn; 267 struct fatcache *closest = NULL; 268 269 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup"); 270 271 for (i = 0; i < FC_SIZE; i++) { 272 cn = dep->de_fc[i].fc_frcn; 273 if (cn != FCE_EMPTY && cn <= findcn) { 274 if (closest == NULL || cn > closest->fc_frcn) 275 closest = &dep->de_fc[i]; 276 } 277 } 278 if (closest) { 279 *frcnp = closest->fc_frcn; 280 *fsrcnp = closest->fc_fsrcn; 281 } 282} 283 284/* 285 * Purge the FAT cache in denode dep of all entries relating to file 286 * relative cluster frcn and beyond. 287 */ 288void 289fc_purge(struct denode *dep, u_int frcn) 290{ 291 int i; 292 struct fatcache *fcp; 293 294 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge"); 295 296 fcp = dep->de_fc; 297 for (i = 0; i < FC_SIZE; i++, fcp++) { 298 if (fcp->fc_frcn >= frcn) 299 fcp->fc_frcn = FCE_EMPTY; 300 } 301} 302 303/* 304 * Update the FAT. 305 * If mirroring the FAT, update all copies, with the first copy as last. 306 * Else update only the current FAT (ignoring the others). 307 * 308 * pmp - msdosfsmount structure for filesystem to update 309 * bp - addr of modified FAT block 310 * fatbn - block number relative to begin of filesystem of the modified FAT block. 311 */ 312static void 313updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn) 314{ 315 struct buf *bpn; 316 int cleanfat, i; 317 318#ifdef MSDOSFS_DEBUG 319 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 320#endif 321 322 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 323 /* 324 * Now copy the block(s) of the modified FAT to the other copies of 325 * the FAT and write them out. This is faster than reading in the 326 * other FATs and then writing them back out. This could tie up 327 * the FAT for quite a while. Preventing others from accessing it. 328 * To prevent us from going after the FAT quite so much we use 329 * delayed writes, unless they specified "synchronous" when the 330 * filesystem was mounted. If synch is asked for then use 331 * bwrite()'s and really slow things down. 332 */ 333 if (fatbn != pmp->pm_fatblk || FAT12(pmp)) 334 cleanfat = 0; 335 else if (FAT16(pmp)) 336 cleanfat = 16; 337 else 338 cleanfat = 32; 339 for (i = 1; i < pmp->pm_FATs; i++) { 340 fatbn += pmp->pm_FATsecs; 341 /* getblk() never fails */ 342 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 343 0, 0, 0); 344 memcpy(bpn->b_data, bp->b_data, bp->b_bcount); 345 /* Force the clean bit on in the other copies. */ 346 if (cleanfat == 16) 347 ((uint8_t *)bpn->b_data)[3] |= 0x80; 348 else if (cleanfat == 32) 349 ((uint8_t *)bpn->b_data)[7] |= 0x08; 350 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 351 bwrite(bpn); 352 else 353 bdwrite(bpn); 354 } 355 } 356 357 /* 358 * Write out the first (or current) FAT last. 359 */ 360 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 361 bwrite(bp); 362 else 363 bdwrite(bp); 364} 365 366/* 367 * Updating entries in 12 bit FATs is a pain in the butt. 368 * 369 * The following picture shows where nibbles go when moving from a 12 bit 370 * cluster number into the appropriate bytes in the FAT. 371 * 372 * byte m byte m+1 byte m+2 373 * +----+----+ +----+----+ +----+----+ 374 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 375 * +----+----+ +----+----+ +----+----+ 376 * 377 * +----+----+----+ +----+----+----+ 378 * | 3 0 1 | | 4 5 2 | 379 * +----+----+----+ +----+----+----+ 380 * cluster n cluster n+1 381 * 382 * Where n is even. m = n + (n >> 2) 383 * 384 */ 385static __inline void 386usemap_alloc(struct msdosfsmount *pmp, u_long cn) 387{ 388 389 MSDOSFS_ASSERT_MP_LOCKED(pmp); 390 391 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 392 pmp->pm_maxcluster)); 393 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 394 ("usemap_alloc on ro msdosfs mount")); 395 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & 396 (1U << (cn % N_INUSEBITS))) == 0, 397 ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS, 398 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 399 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 400 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little")); 401 pmp->pm_freeclustercount--; 402 pmp->pm_flags |= MSDOSFS_FSIMOD; 403} 404 405static int 406usemap_free(struct msdosfsmount *pmp, u_long cn) 407{ 408 409 MSDOSFS_ASSERT_MP_LOCKED(pmp); 410 411 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 412 pmp->pm_maxcluster)); 413 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 414 ("usemap_free on ro msdosfs mount")); 415 if ((pmp->pm_inusemap[cn / N_INUSEBITS] & 416 (1U << (cn % N_INUSEBITS))) == 0) { 417 printf("%s: Freeing unused sector %ld %ld %x\n", 418 pmp->pm_mountp->mnt_stat.f_mntonname, cn, cn % N_INUSEBITS, 419 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS]); 420 msdosfs_integrity_error(pmp); 421 return (EINTEGRITY); 422 } 423 pmp->pm_freeclustercount++; 424 pmp->pm_flags |= MSDOSFS_FSIMOD; 425 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1U << (cn % N_INUSEBITS)); 426 return (0); 427} 428 429void 430clusterfree(struct msdosfsmount *pmp, u_long cluster) 431{ 432 int error; 433 u_long oldcn; 434 435 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 436 if (error != 0) 437 return; 438 /* 439 * If the cluster was successfully marked free, then update 440 * the count of free clusters, and turn off the "allocated" 441 * bit in the "in use" cluster bit map. 442 */ 443 MSDOSFS_LOCK_MP(pmp); 444 error = usemap_free(pmp, cluster); 445 MSDOSFS_UNLOCK_MP(pmp); 446} 447 448/* 449 * Get or Set or 'Get and Set' the cluster'th entry in the FAT. 450 * 451 * function - whether to get or set a FAT entry 452 * pmp - address of the msdosfsmount structure for the filesystem 453 * whose FAT is to be manipulated. 454 * cn - which cluster is of interest 455 * oldcontents - address of a word that is to receive the contents of the 456 * cluster'th entry if this is a get function 457 * newcontents - the new value to be written into the cluster'th element of 458 * the FAT if this is a set function. 459 * 460 * This function can also be used to free a cluster by setting the FAT entry 461 * for a cluster to 0. 462 * 463 * All copies of the FAT are updated if this is a set function. NOTE: If 464 * fatentry() marks a cluster as free it does not update the inusemap in 465 * the msdosfsmount structure. This is left to the caller. 466 */ 467int 468fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, 469 u_long newcontents) 470{ 471 int error; 472 u_long readcn; 473 u_long bn, bo, bsize, byteoffset; 474 struct buf *bp; 475 476#ifdef MSDOSFS_DEBUG 477 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 478 function, pmp, cn, oldcontents, newcontents); 479#endif 480 481#ifdef DIAGNOSTIC 482 /* 483 * Be sure they asked us to do something. 484 */ 485 if ((function & (FAT_SET | FAT_GET)) == 0) { 486#ifdef MSDOSFS_DEBUG 487 printf("fatentry(): function code doesn't specify get or set\n"); 488#endif 489 return (EINVAL); 490 } 491 492 /* 493 * If they asked us to return a cluster number but didn't tell us 494 * where to put it, give them an error. 495 */ 496 if ((function & FAT_GET) && oldcontents == NULL) { 497#ifdef MSDOSFS_DEBUG 498 printf("fatentry(): get function with no place to put result\n"); 499#endif 500 return (EINVAL); 501 } 502#endif 503 504 /* 505 * Be sure the requested cluster is in the filesystem. 506 */ 507 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 508 return (EINVAL); 509 510 byteoffset = FATOFS(pmp, cn); 511 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 512 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 513 if (error) { 514 return (error); 515 } 516 517 if (function & FAT_GET) { 518 if (FAT32(pmp)) 519 readcn = getulong(bp->b_data + bo); 520 else 521 readcn = getushort(bp->b_data + bo); 522 if (FAT12(pmp) & (cn & 1)) 523 readcn >>= 4; 524 readcn &= pmp->pm_fatmask; 525 /* map reserved FAT entries to same values for all FATs */ 526 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 527 readcn |= ~pmp->pm_fatmask; 528 *oldcontents = readcn; 529 } 530 if (function & FAT_SET) { 531 switch (pmp->pm_fatmask) { 532 case FAT12_MASK: 533 readcn = getushort(bp->b_data + bo); 534 if (cn & 1) { 535 readcn &= 0x000f; 536 readcn |= newcontents << 4; 537 } else { 538 readcn &= 0xf000; 539 readcn |= newcontents & 0xfff; 540 } 541 putushort(bp->b_data + bo, readcn); 542 break; 543 case FAT16_MASK: 544 putushort(bp->b_data + bo, newcontents); 545 break; 546 case FAT32_MASK: 547 /* 548 * According to spec we have to retain the 549 * high order bits of the FAT entry. 550 */ 551 readcn = getulong(bp->b_data + bo); 552 readcn &= ~FAT32_MASK; 553 readcn |= newcontents & FAT32_MASK; 554 putulong(bp->b_data + bo, readcn); 555 break; 556 } 557 updatefats(pmp, bp, bn); 558 bp = NULL; 559 pmp->pm_fmod = 1; 560 } 561 if (bp) 562 brelse(bp); 563 return (0); 564} 565 566/* 567 * Update a contiguous cluster chain 568 * 569 * pmp - mount point 570 * start - first cluster of chain 571 * count - number of clusters in chain 572 * fillwith - what to write into FAT entry of last cluster 573 */ 574static int 575fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) 576{ 577 int error; 578 u_long bn, bo, bsize, byteoffset, readcn, newc; 579 struct buf *bp; 580 581#ifdef MSDOSFS_DEBUG 582 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 583 pmp, start, count, fillwith); 584#endif 585 /* 586 * Be sure the clusters are in the filesystem. 587 */ 588 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 589 return (EINVAL); 590 591 while (count > 0) { 592 byteoffset = FATOFS(pmp, start); 593 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 594 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 595 if (error) { 596 return (error); 597 } 598 while (count > 0) { 599 start++; 600 newc = --count > 0 ? start : fillwith; 601 switch (pmp->pm_fatmask) { 602 case FAT12_MASK: 603 readcn = getushort(bp->b_data + bo); 604 if (start & 1) { 605 readcn &= 0xf000; 606 readcn |= newc & 0xfff; 607 } else { 608 readcn &= 0x000f; 609 readcn |= newc << 4; 610 } 611 putushort(bp->b_data + bo, readcn); 612 bo++; 613 if (!(start & 1)) 614 bo++; 615 break; 616 case FAT16_MASK: 617 putushort(bp->b_data + bo, newc); 618 bo += 2; 619 break; 620 case FAT32_MASK: 621 readcn = getulong(bp->b_data + bo); 622 readcn &= ~pmp->pm_fatmask; 623 readcn |= newc & pmp->pm_fatmask; 624 putulong(bp->b_data + bo, readcn); 625 bo += 4; 626 break; 627 } 628 if (bo >= bsize) 629 break; 630 } 631 updatefats(pmp, bp, bn); 632 } 633 pmp->pm_fmod = 1; 634 return (0); 635} 636 637/* 638 * Check the length of a free cluster chain starting at start. 639 * 640 * pmp - mount point 641 * start - start of chain 642 * count - maximum interesting length 643 */ 644static int 645chainlength(struct msdosfsmount *pmp, u_long start, u_long count) 646{ 647 u_long idx, max_idx; 648 u_int map; 649 u_long len; 650 651 MSDOSFS_ASSERT_MP_LOCKED(pmp); 652 653 if (start > pmp->pm_maxcluster) 654 return (0); 655 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 656 idx = start / N_INUSEBITS; 657 start %= N_INUSEBITS; 658 map = pmp->pm_inusemap[idx]; 659 map &= ~((1U << start) - 1); 660 if (map) { 661 len = ffs(map) - 1 - start; 662 len = MIN(len, count); 663 if (start + len > pmp->pm_maxcluster) 664 len = pmp->pm_maxcluster - start + 1; 665 return (len); 666 } 667 len = N_INUSEBITS - start; 668 if (len >= count) { 669 len = count; 670 if (start + len > pmp->pm_maxcluster) 671 len = pmp->pm_maxcluster - start + 1; 672 return (len); 673 } 674 while (++idx <= max_idx) { 675 if (len >= count) 676 break; 677 map = pmp->pm_inusemap[idx]; 678 if (map) { 679 len += ffs(map) - 1; 680 break; 681 } 682 len += N_INUSEBITS; 683 } 684 len = MIN(len, count); 685 if (start + len > pmp->pm_maxcluster) 686 len = pmp->pm_maxcluster - start + 1; 687 return (len); 688} 689 690/* 691 * Allocate contigous free clusters. 692 * 693 * pmp - mount point. 694 * start - start of cluster chain. 695 * count - number of clusters to allocate. 696 * fillwith - put this value into the FAT entry for the 697 * last allocated cluster. 698 * retcluster - put the first allocated cluster's number here. 699 * got - how many clusters were actually allocated. 700 */ 701static int 702chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, 703 u_long fillwith, u_long *retcluster, u_long *got) 704{ 705 int error; 706 u_long cl, n; 707 708 MSDOSFS_ASSERT_MP_LOCKED(pmp); 709 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 710 ("chainalloc on ro msdosfs mount")); 711 712 for (cl = start, n = count; n-- > 0;) 713 usemap_alloc(pmp, cl++); 714 pmp->pm_nxtfree = start + count; 715 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 716 pmp->pm_nxtfree = CLUST_FIRST; 717 pmp->pm_flags |= MSDOSFS_FSIMOD; 718 error = fatchain(pmp, start, count, fillwith); 719 if (error != 0) { 720 for (cl = start, n = count; n-- > 0;) 721 (void)usemap_free(pmp, cl++); 722 return (error); 723 } 724#ifdef MSDOSFS_DEBUG 725 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 726 start, count); 727#endif 728 if (retcluster) 729 *retcluster = start; 730 if (got) 731 *got = count; 732 return (0); 733} 734 735/* 736 * Allocate contiguous free clusters. 737 * 738 * pmp - mount point. 739 * start - preferred start of cluster chain. 740 * count - number of clusters requested. 741 * fillwith - put this value into the FAT entry for the 742 * last allocated cluster. 743 * retcluster - put the first allocated cluster's number here. 744 * got - how many clusters were actually allocated. 745 */ 746int 747clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 748 u_long fillwith, u_long *retcluster, u_long *got) 749{ 750 int error; 751 752 MSDOSFS_LOCK_MP(pmp); 753 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 754 MSDOSFS_UNLOCK_MP(pmp); 755 return (error); 756} 757 758static int 759clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 760 u_long fillwith, u_long *retcluster, u_long *got) 761{ 762 u_long idx; 763 u_long len, newst, foundl, cn, l; 764 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 765 u_int map; 766 767 MSDOSFS_ASSERT_MP_LOCKED(pmp); 768 769#ifdef MSDOSFS_DEBUG 770 printf("clusteralloc(): find %lu clusters\n", count); 771#endif 772 if (start) { 773 if ((len = chainlength(pmp, start, count)) >= count) 774 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 775 } else 776 len = 0; 777 778 newst = pmp->pm_nxtfree; 779 foundl = 0; 780 781 for (cn = newst; cn <= pmp->pm_maxcluster;) { 782 idx = cn / N_INUSEBITS; 783 map = pmp->pm_inusemap[idx]; 784 map |= (1U << (cn % N_INUSEBITS)) - 1; 785 if (map != FULL_RUN) { 786 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 787 if ((l = chainlength(pmp, cn, count)) >= count) 788 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 789 if (l > foundl) { 790 foundcn = cn; 791 foundl = l; 792 } 793 cn += l + 1; 794 continue; 795 } 796 cn += N_INUSEBITS - cn % N_INUSEBITS; 797 } 798 for (cn = 0; cn < newst;) { 799 idx = cn / N_INUSEBITS; 800 map = pmp->pm_inusemap[idx]; 801 map |= (1U << (cn % N_INUSEBITS)) - 1; 802 if (map != FULL_RUN) { 803 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 804 if ((l = chainlength(pmp, cn, count)) >= count) 805 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 806 if (l > foundl) { 807 foundcn = cn; 808 foundl = l; 809 } 810 cn += l + 1; 811 continue; 812 } 813 cn += N_INUSEBITS - cn % N_INUSEBITS; 814 } 815 816 if (!foundl) 817 return (ENOSPC); 818 819 if (len) 820 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 821 else 822 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 823} 824 825/* 826 * Free a chain of clusters. 827 * 828 * pmp - address of the msdosfs mount structure for the filesystem 829 * containing the cluster chain to be freed. 830 * startcluster - number of the 1st cluster in the chain of clusters to be 831 * freed. 832 */ 833int 834freeclusterchain(struct msdosfsmount *pmp, u_long cluster) 835{ 836 int error; 837 struct buf *bp = NULL; 838 u_long bn, bo, bsize, byteoffset; 839 u_long readcn, lbn = -1; 840 841 MSDOSFS_LOCK_MP(pmp); 842 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 843 byteoffset = FATOFS(pmp, cluster); 844 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 845 if (lbn != bn) { 846 if (bp) 847 updatefats(pmp, bp, lbn); 848 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 849 if (error) { 850 MSDOSFS_UNLOCK_MP(pmp); 851 return (error); 852 } 853 lbn = bn; 854 } 855 error = usemap_free(pmp, cluster); 856 if (error != 0) { 857 updatefats(pmp, bp, lbn); 858 MSDOSFS_UNLOCK_MP(pmp); 859 return (error); 860 } 861 switch (pmp->pm_fatmask) { 862 case FAT12_MASK: 863 readcn = getushort(bp->b_data + bo); 864 if (cluster & 1) { 865 cluster = readcn >> 4; 866 readcn &= 0x000f; 867 readcn |= MSDOSFSFREE << 4; 868 } else { 869 cluster = readcn; 870 readcn &= 0xf000; 871 readcn |= MSDOSFSFREE & 0xfff; 872 } 873 putushort(bp->b_data + bo, readcn); 874 break; 875 case FAT16_MASK: 876 cluster = getushort(bp->b_data + bo); 877 putushort(bp->b_data + bo, MSDOSFSFREE); 878 break; 879 case FAT32_MASK: 880 cluster = getulong(bp->b_data + bo); 881 putulong(bp->b_data + bo, 882 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 883 break; 884 } 885 cluster &= pmp->pm_fatmask; 886 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 887 cluster |= pmp->pm_fatmask; 888 } 889 if (bp) 890 updatefats(pmp, bp, bn); 891 MSDOSFS_UNLOCK_MP(pmp); 892 return (0); 893} 894 895/* 896 * Read in FAT blocks looking for free clusters. For every free cluster 897 * found turn off its corresponding bit in the pm_inusemap. 898 */ 899int 900fillinusemap(struct msdosfsmount *pmp) 901{ 902 struct buf *bp; 903 u_long bn, bo, bsize, byteoffset, cn, readcn; 904 int error; 905 906 MSDOSFS_ASSERT_MP_LOCKED(pmp); 907 bp = NULL; 908 909 /* 910 * Mark all clusters in use, we mark the free ones in the FAT scan 911 * loop further down. 912 */ 913 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 914 pmp->pm_inusemap[cn] = FULL_RUN; 915 916 /* 917 * Figure how many free clusters are in the filesystem by ripping 918 * through the FAT counting the number of entries whose content is 919 * zero. These represent free clusters. 920 */ 921 pmp->pm_freeclustercount = 0; 922 for (cn = 0; cn <= pmp->pm_maxcluster; cn++) { 923 byteoffset = FATOFS(pmp, cn); 924 bo = byteoffset % pmp->pm_fatblocksize; 925 if (bo == 0) { 926 /* Read new FAT block */ 927 if (bp != NULL) 928 brelse(bp); 929 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 930 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 931 if (error != 0) 932 return (error); 933 } 934 if (FAT32(pmp)) 935 readcn = getulong(bp->b_data + bo); 936 else 937 readcn = getushort(bp->b_data + bo); 938 if (FAT12(pmp) && (cn & 1)) 939 readcn >>= 4; 940 readcn &= pmp->pm_fatmask; 941 942 /* 943 * Check if the FAT ID matches the BPB's media descriptor and 944 * all other bits are set to 1. 945 */ 946 if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) | 947 pmp->pm_bpb.bpbMedia)) { 948#ifdef MSDOSFS_DEBUG 949 printf("mountmsdosfs(): Media descriptor in BPB" 950 "does not match FAT ID\n"); 951#endif 952 brelse(bp); 953 return (EINVAL); 954 } else if (readcn == CLUST_FREE) { 955 error = usemap_free(pmp, cn); 956 if (error != 0) { 957 brelse(bp); 958 return (error); 959 } 960 } 961 } 962 if (bp != NULL) 963 brelse(bp); 964 965 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster + 966 N_INUSEBITS) / N_INUSEBITS; cn++) 967 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 968 969 return (0); 970} 971 972/* 973 * Allocate a new cluster and chain it onto the end of the file. 974 * 975 * dep - the file to extend 976 * count - number of clusters to allocate 977 * bpp - where to return the address of the buf header for the first new 978 * file block 979 * ncp - where to put cluster number of the first newly allocated cluster 980 * If this pointer is 0, do not return the cluster number. 981 * flags - see fat.h 982 * 983 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 984 * the de_flag field of the denode and it does not change the de_FileSize 985 * field. This is left for the caller to do. 986 */ 987int 988extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp, 989 int flags) 990{ 991 int error; 992 u_long frcn; 993 u_long cn, got; 994 struct msdosfsmount *pmp = dep->de_pmp; 995 struct buf *bp; 996 daddr_t blkno; 997 998 /* 999 * Don't try to extend the root directory 1000 */ 1001 if (dep->de_StartCluster == MSDOSFSROOT 1002 && (dep->de_Attributes & ATTR_DIRECTORY)) { 1003#ifdef MSDOSFS_DEBUG 1004 printf("extendfile(): attempt to extend root directory\n"); 1005#endif 1006 return (ENOSPC); 1007 } 1008 1009 /* 1010 * If the "file's last cluster" cache entry is empty, and the file 1011 * is not empty, then fill the cache entry by calling pcbmap(). 1012 */ 1013 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 1014 dep->de_StartCluster != 0) { 1015 error = pcbmap(dep, 0xffff, 0, &cn, 0); 1016 /* we expect it to return E2BIG */ 1017 if (error != E2BIG) 1018 return (error); 1019 } 1020 1021 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 1022 dep->de_fc[FC_LASTFC].fc_frcn; 1023 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 1024 dep->de_fc[FC_LASTFC].fc_fsrcn; 1025 while (count > 0) { 1026 /* 1027 * Allocate a new cluster chain and cat onto the end of the 1028 * file. If the file is empty we make de_StartCluster point 1029 * to the new block. Note that de_StartCluster being 0 is 1030 * sufficient to be sure the file is empty since we exclude 1031 * attempts to extend the root directory above, and the root 1032 * dir is the only file with a startcluster of 0 that has 1033 * blocks allocated (sort of). 1034 */ 1035 if (dep->de_StartCluster == 0) 1036 cn = 0; 1037 else 1038 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1039 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1040 if (error) 1041 return (error); 1042 1043 count -= got; 1044 1045 /* 1046 * Give them the filesystem relative cluster number if they want 1047 * it. 1048 */ 1049 if (ncp) { 1050 *ncp = cn; 1051 ncp = NULL; 1052 } 1053 1054 if (dep->de_StartCluster == 0) { 1055 dep->de_StartCluster = cn; 1056 frcn = 0; 1057 } else { 1058 error = fatentry(FAT_SET, pmp, 1059 dep->de_fc[FC_LASTFC].fc_fsrcn, 1060 0, cn); 1061 if (error) { 1062 clusterfree(pmp, cn); 1063 return (error); 1064 } 1065 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1066 } 1067 1068 /* 1069 * Update the "last cluster of the file" entry in the 1070 * denode's FAT cache. 1071 */ 1072 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1073 1074 if (flags & DE_CLEAR) { 1075 while (got-- > 0) { 1076 /* 1077 * Get the buf header for the new block of the file. 1078 */ 1079 if (dep->de_Attributes & ATTR_DIRECTORY) 1080 bp = getblk(pmp->pm_devvp, 1081 cntobn(pmp, cn++), 1082 pmp->pm_bpcluster, 0, 0, 0); 1083 else { 1084 bp = getblk(DETOV(dep), 1085 frcn++, 1086 pmp->pm_bpcluster, 0, 0, 0); 1087 /* 1088 * Do the bmap now, as in msdosfs_write 1089 */ 1090 if (pcbmap(dep, 1091 bp->b_lblkno, 1092 &blkno, 0, 0)) 1093 bp->b_blkno = -1; 1094 if (bp->b_blkno == -1) 1095 panic("extendfile: pcbmap"); 1096 else 1097 bp->b_blkno = blkno; 1098 } 1099 clrbuf(bp); 1100 if (bpp) { 1101 *bpp = bp; 1102 bpp = NULL; 1103 } else { 1104 bdwrite(bp); 1105 } 1106 if (vm_page_count_severe() || 1107 buf_dirty_count_severe()) 1108 vn_fsync_buf(DETOV(dep), MNT_WAIT); 1109 } 1110 } 1111 } 1112 1113 return (0); 1114} 1115 1116/*- 1117 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1118 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1119 * this bit is not defined for FAT12 volumes, which are always assumed to 1120 * be clean. 1121 * 1122 * The fatentry() routine only works on cluster numbers that a file could 1123 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1124 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1125 * 1126 * Inputs: 1127 * pmp The MS-DOS volume to mark 1128 * dirty Non-zero if the volume should be marked dirty; zero if it 1129 * should be marked clean 1130 * 1131 * Result: 1132 * 0 Success 1133 * EROFS Volume is read-only 1134 * ? (other errors from called routines) 1135 */ 1136int 1137markvoldirty_upgrade(struct msdosfsmount *pmp, bool dirty, bool rw_upgrade) 1138{ 1139 struct buf *bp; 1140 u_long bn, bo, bsize, byteoffset, fatval; 1141 int error; 1142 1143 /* 1144 * FAT12 does not support a "clean" bit, so don't do anything for 1145 * FAT12. 1146 */ 1147 if (FAT12(pmp)) 1148 return (0); 1149 1150 /* 1151 * Can't change the bit on a read-only filesystem, except as part of 1152 * ro->rw upgrade. 1153 */ 1154 if ((pmp->pm_flags & MSDOSFSMNT_RONLY) != 0 && !rw_upgrade) 1155 return (EROFS); 1156 1157 /* 1158 * Fetch the block containing the FAT entry. It is given by the 1159 * pseudo-cluster 1. 1160 */ 1161 byteoffset = FATOFS(pmp, 1); 1162 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1163 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1164 if (error) 1165 return (error); 1166 1167 /* 1168 * Get the current value of the FAT entry and set/clear the relevant 1169 * bit. Dirty means clear the "clean" bit; clean means set the 1170 * "clean" bit. 1171 */ 1172 if (FAT32(pmp)) { 1173 /* FAT32 uses bit 27. */ 1174 fatval = getulong(&bp->b_data[bo]); 1175 if (dirty) 1176 fatval &= 0xF7FFFFFF; 1177 else 1178 fatval |= 0x08000000; 1179 putulong(&bp->b_data[bo], fatval); 1180 } else { 1181 /* Must be FAT16; use bit 15. */ 1182 fatval = getushort(&bp->b_data[bo]); 1183 if (dirty) 1184 fatval &= 0x7FFF; 1185 else 1186 fatval |= 0x8000; 1187 putushort(&bp->b_data[bo], fatval); 1188 } 1189 1190 /* 1191 * The concern here is that a devvp may be readonly, without reporting 1192 * itself as such through the usual channels. In that case, we'd like 1193 * it if attempting to mount msdosfs rw didn't panic the system. 1194 * 1195 * markvoldirty is invoked as the first write on backing devvps when 1196 * either msdosfs is mounted for the first time, or a ro mount is 1197 * upgraded to rw. 1198 * 1199 * In either event, if a write error occurs dirtying the volume: 1200 * - No user data has been permitted to be written to cache yet. 1201 * - We can abort the high-level operation (mount, or ro->rw) safely. 1202 * - We don't derive any benefit from leaving a zombie dirty buf in 1203 * the cache that can not be cleaned or evicted. 1204 * 1205 * So, mark B_INVALONERR to have bwrite() -> brelse() detect that 1206 * condition and force-invalidate our write to the block if it occurs. 1207 * 1208 * PR 210316 provides more context on the discovery and diagnosis of 1209 * the problem, as well as earlier attempts to solve it. 1210 */ 1211 bp->b_flags |= B_INVALONERR; 1212 1213 /* Write out the modified FAT block synchronously. */ 1214 return (bwrite(bp)); 1215} 1216