1 /* $FreeBSD$ */ 2 /* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 ws Exp $ */ 3 4 /*- 5 * SPDX-License-Identifier: BSD-4-Clause 6 * 7 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank. 8 * Copyright (C) 1994, 1995, 1997 TooLs GmbH. 9 * All rights reserved. 10 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below). 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by TooLs GmbH. 23 * 4. The name of TooLs GmbH may not be used to endorse or promote products 24 * derived from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 31 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 32 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 33 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 34 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 35 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 /*- 38 * Written by Paul Popelka (paulp@uts.amdahl.com) 39 * 40 * You can do anything you want with this software, just don't say you wrote 41 * it, and don't remove this notice. 42 * 43 * This software is provided "as is". 44 * 45 * The author supplies this software to be publicly redistributed on the 46 * understanding that the author is not responsible for the correct 47 * functioning of this software in any circumstances and is not liable for 48 * any damages caused by this software. 49 * 50 * October 1992 51 */ 52 53 #include <sys/param.h> 54 #include <sys/systm.h> 55 #include <sys/buf.h> 56 #include <sys/mount.h> 57 #include <sys/vnode.h> 58 59 #include <sys/buf2.h> 60 61 #include <vfs/msdosfs/bpb.h> 62 #include <vfs/msdosfs/direntry.h> 63 #include <vfs/msdosfs/denode.h> 64 #include <vfs/msdosfs/fat.h> 65 #include <vfs/msdosfs/msdosfsmount.h> 66 67 #define FULL_RUN ((u_int)0xffffffff) 68 69 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 70 u_long *fsrcnp); 71 static int clusteralloc1(struct msdosfsmount *pmp, u_long start, 72 u_long count, u_long fillwith, u_long *retcluster, 73 u_long *got); 74 75 /* 76 * Given a byte offset `ofs` within FAT, return block number in backing device, 77 * block size, and byte offset within a block in FAT. 78 */ 79 static void 80 fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep, 81 u_long *bop) 82 { 83 u_long bn, size; 84 85 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 86 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) * DEV_BSIZE; 87 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 88 89 if (bnp) 90 *bnp = bn; 91 if (sizep) 92 *sizep = size; 93 if (bop) 94 *bop = ofs % pmp->pm_fatblocksize; 95 } 96 97 /* 98 * Map the logical cluster number of a file into a physical disk sector 99 * that is filesystem relative. 100 * 101 * dep - address of denode representing the file of interest 102 * findcn - file relative cluster whose filesystem relative cluster number 103 * and/or block number are/is to be found 104 * bnp - address of where to place the filesystem relative block number. 105 * If this pointer is null then don't return this quantity. 106 * cnp - address of where to place the filesystem relative cluster number. 107 * If this pointer is null then don't return this quantity. 108 * sp - pointer to returned block size 109 * 110 * NOTE: Either bnp or cnp must be non-null. 111 * This function has one side effect. If the requested file relative cluster 112 * is beyond the end of file, then the actual number of clusters in the file 113 * is returned in *cnp. This is useful for determining how long a directory is. 114 * If cnp is null, nothing is returned. 115 */ 116 int 117 pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp) 118 { 119 int error; 120 u_long i; 121 u_long cn; 122 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 123 u_long byteoffset; 124 u_long bn; 125 u_long bo; 126 struct buf *bp = NULL; 127 u_long bp_bn = -1; 128 struct msdosfsmount *pmp = dep->de_pmp; 129 u_long bsize; 130 131 KASSERT(bnp != NULL || cnp != NULL || sp != NULL, 132 ("pcbmap: extra call")); 133 134 cn = dep->de_StartCluster; 135 /* 136 * The "file" that makes up the root directory is contiguous, 137 * permanently allocated, of fixed size, and is not made up of 138 * clusters. If the cluster number is beyond the end of the root 139 * directory, then return the number of clusters in the file. 140 */ 141 if (cn == MSDOSFSROOT) { 142 if (dep->de_Attributes & ATTR_DIRECTORY) { 143 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 144 if (cnp) 145 *cnp = de_bn2cn(pmp, 146 pmp->pm_rootdirsize); 147 return (E2BIG); 148 } 149 if (bnp) 150 *bnp = pmp->pm_rootdirblk + 151 de_cn2bn(pmp, findcn); 152 if (cnp) 153 *cnp = MSDOSFSROOT; 154 if (sp) 155 *sp = min(pmp->pm_bpcluster, 156 dep->de_FileSize - de_cn2off(pmp, findcn)); 157 return (0); 158 } else { /* just an empty file */ 159 if (cnp) 160 *cnp = 0; 161 return (E2BIG); 162 } 163 } 164 165 /* 166 * All other files do I/O in cluster sized blocks 167 */ 168 if (sp) 169 *sp = pmp->pm_bpcluster; 170 171 /* 172 * Rummage around in the FAT cache, maybe we can avoid tromping 173 * through every FAT entry for the file. And, keep track of how far 174 * off the cache was from where we wanted to be. 175 */ 176 i = 0; 177 fc_lookup(dep, findcn, &i, &cn); 178 179 /* 180 * Handle all other files or directories the normal way. 181 */ 182 for (; i < findcn; i++) { 183 /* 184 * Stop with all reserved clusters, not just with EOF. 185 */ 186 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 187 goto hiteof; 188 byteoffset = FATOFS(pmp, cn); 189 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 190 if (bn != bp_bn) { 191 if (bp) 192 brelse(bp); 193 error = bread(pmp->pm_devvp, de_bn2doff(pmp, bn), 194 bsize, &bp); 195 if (error) { 196 brelse(bp); 197 return (error); 198 } 199 bp_bn = bn; 200 } 201 prevcn = cn; 202 if (bo >= bsize) { 203 if (bp) 204 brelse(bp); 205 return (EIO); 206 } 207 if (FAT32(pmp)) 208 cn = getulong(bp->b_data + bo); 209 else 210 cn = getushort(bp->b_data + bo); 211 if (FAT12(pmp) && (prevcn & 1)) 212 cn >>= 4; 213 cn &= pmp->pm_fatmask; 214 215 /* 216 * Force the special cluster numbers 217 * to be the same for all cluster sizes 218 * to let the rest of msdosfs handle 219 * all cases the same. 220 */ 221 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 222 cn |= ~pmp->pm_fatmask; 223 } 224 225 if (!MSDOSFSEOF(pmp, cn)) { 226 if (bp) 227 brelse(bp); 228 if (bnp) 229 *bnp = cntobn(pmp, cn); 230 if (cnp) 231 *cnp = cn; 232 fc_setcache(dep, FC_LASTMAP, i, cn); 233 return (0); 234 } 235 236 hiteof: 237 if (cnp) 238 *cnp = i; 239 if (bp) 240 brelse(bp); 241 /* update last file cluster entry in the FAT cache */ 242 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 243 return (E2BIG); 244 } 245 246 /* 247 * Find the closest entry in the FAT cache to the cluster we are looking 248 * for. 249 */ 250 static void 251 fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp) 252 { 253 int i; 254 u_long cn; 255 struct fatcache *closest = NULL; 256 257 for (i = 0; i < FC_SIZE; i++) { 258 cn = dep->de_fc[i].fc_frcn; 259 if (cn != FCE_EMPTY && cn <= findcn) { 260 if (closest == NULL || cn > closest->fc_frcn) 261 closest = &dep->de_fc[i]; 262 } 263 } 264 if (closest) { 265 *frcnp = closest->fc_frcn; 266 *fsrcnp = closest->fc_fsrcn; 267 } 268 } 269 270 /* 271 * Purge the FAT cache in denode dep of all entries relating to file 272 * relative cluster frcn and beyond. 273 */ 274 void 275 fc_purge(struct denode *dep, u_int frcn) 276 { 277 int i; 278 struct fatcache *fcp; 279 280 fcp = dep->de_fc; 281 for (i = 0; i < FC_SIZE; i++, fcp++) { 282 if (fcp->fc_frcn >= frcn) 283 fcp->fc_frcn = FCE_EMPTY; 284 } 285 } 286 287 /* 288 * Update the FAT. 289 * If mirroring the FAT, update all copies, with the first copy as last. 290 * Else update only the current FAT (ignoring the others). 291 * 292 * pmp - msdosfsmount structure for filesystem to update 293 * bp - addr of modified FAT block 294 * fatbn - block number relative to begin of filesystem of the modified FAT block. 295 */ 296 static void 297 updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn) 298 { 299 struct buf *bpn; 300 int cleanfat, i; 301 302 mprintf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 303 304 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 305 /* 306 * Now copy the block(s) of the modified FAT to the other copies of 307 * the FAT and write them out. This is faster than reading in the 308 * other FATs and then writing them back out. This could tie up 309 * the FAT for quite a while. Preventing others from accessing it. 310 * To prevent us from going after the FAT quite so much we use 311 * delayed writes, unless they specified "synchronous" when the 312 * filesystem was mounted. If synch is asked for then use 313 * bwrite()'s and really slow things down. 314 */ 315 if (fatbn != pmp->pm_fatblk || FAT12(pmp)) 316 cleanfat = 0; 317 else if (FAT16(pmp)) 318 cleanfat = 16; 319 else 320 cleanfat = 32; 321 for (i = 1; i < pmp->pm_FATs; i++) { 322 fatbn += pmp->pm_FATsecs; 323 /* getblk() never fails */ 324 bpn = getblk(pmp->pm_devvp, de_bn2doff(pmp, fatbn), 325 bp->b_bcount, 0, 0); 326 memcpy(bpn->b_data, bp->b_data, bp->b_bcount); 327 /* Force the clean bit on in the other copies. */ 328 if (cleanfat == 16) 329 ((uint8_t *)bpn->b_data)[3] |= 0x80; 330 else if (cleanfat == 32) 331 ((uint8_t *)bpn->b_data)[7] |= 0x08; 332 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 333 bwrite(bpn); 334 else 335 bdwrite(bpn); 336 } 337 } 338 339 /* 340 * Write out the first (or current) FAT last. 341 */ 342 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 343 bwrite(bp); 344 else 345 bdwrite(bp); 346 } 347 348 /* 349 * Updating entries in 12 bit FATs is a pain in the butt. 350 * 351 * The following picture shows where nibbles go when moving from a 12 bit 352 * cluster number into the appropriate bytes in the FAT. 353 * 354 * byte m byte m+1 byte m+2 355 * +----+----+ +----+----+ +----+----+ 356 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 357 * +----+----+ +----+----+ +----+----+ 358 * 359 * +----+----+----+ +----+----+----+ 360 * | 3 0 1 | | 4 5 2 | 361 * +----+----+----+ +----+----+----+ 362 * cluster n cluster n+1 363 * 364 * Where n is even. m = n + (n >> 2) 365 * 366 */ 367 static __inline void 368 usemap_alloc(struct msdosfsmount *pmp, u_long cn) 369 { 370 MSDOSFS_ASSERT_MP_LOCKED(pmp); 371 372 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 373 pmp->pm_maxcluster)); 374 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 375 ("usemap_alloc on ro msdosfs mount")); 376 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 377 == 0, ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS, 378 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 379 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 380 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little")); 381 pmp->pm_freeclustercount--; 382 pmp->pm_flags |= MSDOSFS_FSIMOD; 383 } 384 385 static __inline void 386 usemap_free(struct msdosfsmount *pmp, u_long cn) 387 { 388 MSDOSFS_ASSERT_MP_LOCKED(pmp); 389 390 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 391 pmp->pm_maxcluster)); 392 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 393 ("usemap_free on ro msdosfs mount")); 394 pmp->pm_freeclustercount++; 395 pmp->pm_flags |= MSDOSFS_FSIMOD; 396 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 397 != 0, ("Freeing unused 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 } 401 402 int 403 clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp) 404 { 405 int error; 406 u_long oldcn; 407 408 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 409 if (error) 410 return (error); 411 /* 412 * If the cluster was successfully marked free, then update 413 * the count of free clusters, and turn off the "allocated" 414 * bit in the "in use" cluster bit map. 415 */ 416 MSDOSFS_LOCK_MP(pmp); 417 usemap_free(pmp, cluster); 418 MSDOSFS_UNLOCK_MP(pmp); 419 if (oldcnp) 420 *oldcnp = oldcn; 421 return (0); 422 } 423 424 /* 425 * Get or Set or 'Get and Set' the cluster'th entry in the FAT. 426 * 427 * function - whether to get or set a FAT entry 428 * pmp - address of the msdosfsmount structure for the filesystem 429 * whose FAT is to be manipulated. 430 * cn - which cluster is of interest 431 * oldcontents - address of a word that is to receive the contents of the 432 * cluster'th entry if this is a get function 433 * newcontents - the new value to be written into the cluster'th element of 434 * the FAT if this is a set function. 435 * 436 * This function can also be used to free a cluster by setting the FAT entry 437 * for a cluster to 0. 438 * 439 * All copies of the FAT are updated if this is a set function. NOTE: If 440 * fatentry() marks a cluster as free it does not update the inusemap in 441 * the msdosfsmount structure. This is left to the caller. 442 */ 443 int 444 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, 445 u_long newcontents) 446 { 447 int error; 448 u_long readcn; 449 u_long bn, bo, bsize, byteoffset; 450 struct buf *bp; 451 452 mprintf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 453 function, pmp, cn, oldcontents, newcontents); 454 455 #ifdef DIAGNOSTIC 456 /* 457 * Be sure they asked us to do something. 458 */ 459 if ((function & (FAT_SET | FAT_GET)) == 0) { 460 kprintf("fatentry(): function code doesn't specify get or set\n"); 461 return (EINVAL); 462 } 463 464 /* 465 * If they asked us to return a cluster number but didn't tell us 466 * where to put it, give them an error. 467 */ 468 if ((function & FAT_GET) && oldcontents == NULL) { 469 kprintf("fatentry(): get function with no place to put result\n"); 470 return (EINVAL); 471 } 472 #endif 473 474 /* 475 * Be sure the requested cluster is in the filesystem. 476 */ 477 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 478 return (EINVAL); 479 480 byteoffset = FATOFS(pmp, cn); 481 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 482 error = bread(pmp->pm_devvp, de_bn2doff(pmp, bn), bsize, &bp); 483 if (error) { 484 brelse(bp); 485 return (error); 486 } 487 488 if (function & FAT_GET) { 489 if (FAT32(pmp)) 490 readcn = getulong(bp->b_data + bo); 491 else 492 readcn = getushort(bp->b_data + bo); 493 if (FAT12(pmp) & (cn & 1)) 494 readcn >>= 4; 495 readcn &= pmp->pm_fatmask; 496 /* map reserved FAT entries to same values for all FATs */ 497 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 498 readcn |= ~pmp->pm_fatmask; 499 *oldcontents = readcn; 500 } 501 if (function & FAT_SET) { 502 switch (pmp->pm_fatmask) { 503 case FAT12_MASK: 504 readcn = getushort(bp->b_data + bo); 505 if (cn & 1) { 506 readcn &= 0x000f; 507 readcn |= newcontents << 4; 508 } else { 509 readcn &= 0xf000; 510 readcn |= newcontents & 0xfff; 511 } 512 putushort(bp->b_data + bo, readcn); 513 break; 514 case FAT16_MASK: 515 putushort(bp->b_data + bo, newcontents); 516 break; 517 case FAT32_MASK: 518 /* 519 * According to spec we have to retain the 520 * high order bits of the FAT entry. 521 */ 522 readcn = getulong(bp->b_data + bo); 523 readcn &= ~FAT32_MASK; 524 readcn |= newcontents & FAT32_MASK; 525 putulong(bp->b_data + bo, readcn); 526 break; 527 } 528 updatefats(pmp, bp, bn); 529 bp = NULL; 530 pmp->pm_fmod = 1; 531 } 532 if (bp) 533 brelse(bp); 534 return (0); 535 } 536 537 /* 538 * Update a contiguous cluster chain 539 * 540 * pmp - mount point 541 * start - first cluster of chain 542 * count - number of clusters in chain 543 * fillwith - what to write into FAT entry of last cluster 544 */ 545 static int 546 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) 547 { 548 int error; 549 u_long bn, bo, bsize, byteoffset, readcn, newc; 550 struct buf *bp; 551 552 mprintf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 553 pmp, start, count, fillwith); 554 /* 555 * Be sure the clusters are in the filesystem. 556 */ 557 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 558 return (EINVAL); 559 560 while (count > 0) { 561 byteoffset = FATOFS(pmp, start); 562 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 563 error = bread(pmp->pm_devvp, de_bn2doff(pmp, bn), bsize, &bp); 564 if (error) { 565 brelse(bp); 566 return (error); 567 } 568 while (count > 0) { 569 start++; /* Callers must guarantee contiguous free 570 clusters. */ 571 newc = --count > 0 ? start : fillwith; 572 switch (pmp->pm_fatmask) { 573 case FAT12_MASK: 574 readcn = getushort(bp->b_data + bo); 575 if (start & 1) { 576 readcn &= 0xf000; 577 readcn |= newc & 0xfff; 578 } else { 579 readcn &= 0x000f; 580 readcn |= newc << 4; 581 } 582 putushort(bp->b_data + bo, readcn); 583 bo++; 584 if (!(start & 1)) 585 bo++; 586 break; 587 case FAT16_MASK: 588 putushort(bp->b_data + bo, newc); 589 bo += 2; 590 break; 591 case FAT32_MASK: 592 readcn = getulong(bp->b_data + bo); 593 readcn &= ~pmp->pm_fatmask; 594 readcn |= newc & pmp->pm_fatmask; 595 putulong(bp->b_data + bo, readcn); 596 bo += 4; 597 break; 598 } 599 if (bo >= bsize) 600 break; 601 } 602 updatefats(pmp, bp, bn); 603 } 604 pmp->pm_fmod = 1; 605 return (0); 606 } 607 608 /* 609 * Check the length of a free cluster chain starting at start. 610 * 611 * pmp - mount point 612 * start - start of chain 613 * count - maximum interesting length 614 */ 615 static int 616 chainlength(struct msdosfsmount *pmp, u_long start, u_long count) 617 { 618 u_long idx, max_idx; 619 u_int map; 620 u_long len; 621 622 MSDOSFS_ASSERT_MP_LOCKED(pmp); 623 624 if (start > pmp->pm_maxcluster) 625 return (0); 626 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 627 idx = start / N_INUSEBITS; 628 start %= N_INUSEBITS; 629 map = pmp->pm_inusemap[idx]; 630 map &= ~((1 << start) - 1); 631 if (map) { 632 len = ffs(map) - 1 - start; 633 len = MIN(len, count); 634 if (start + len > pmp->pm_maxcluster) 635 len = pmp->pm_maxcluster - start + 1; 636 return (len); 637 } 638 len = N_INUSEBITS - start; 639 if (len >= count) { 640 len = count; 641 if (start + len > pmp->pm_maxcluster) 642 len = pmp->pm_maxcluster - start + 1; 643 return (len); 644 } 645 while (++idx <= max_idx) { 646 if (len >= count) 647 break; 648 map = pmp->pm_inusemap[idx]; 649 if (map) { 650 len += ffs(map) - 1; 651 break; 652 } 653 len += N_INUSEBITS; 654 } 655 len = MIN(len, count); 656 if (start + len > pmp->pm_maxcluster) 657 len = pmp->pm_maxcluster - start + 1; 658 return (len); 659 } 660 661 /* 662 * Allocate contigous free clusters. 663 * 664 * pmp - mount point. 665 * start - start of cluster chain. 666 * count - number of clusters to allocate. 667 * fillwith - put this value into the FAT entry for the 668 * last allocated cluster. 669 * retcluster - put the first allocated cluster's number here. 670 * got - how many clusters were actually allocated. 671 */ 672 static int 673 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, 674 u_long fillwith, u_long *retcluster, u_long *got) 675 { 676 int error; 677 u_long cl, n; 678 679 MSDOSFS_ASSERT_MP_LOCKED(pmp); 680 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 681 ("chainalloc on ro msdosfs mount")); 682 683 for (cl = start, n = count; n-- > 0;) 684 usemap_alloc(pmp, cl++); 685 686 pmp->pm_nxtfree = start + count; 687 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 688 pmp->pm_nxtfree = CLUST_FIRST; 689 pmp->pm_flags |= MSDOSFS_FSIMOD; 690 691 error = fatchain(pmp, start, count, fillwith); 692 if (error != 0) { 693 for (cl = start, n = count; n-- > 0;) 694 usemap_free(pmp, cl++); 695 return (error); 696 } 697 mprintf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 698 start, count); 699 if (retcluster) 700 *retcluster = start; 701 if (got) 702 *got = count; 703 return (0); 704 } 705 706 /* 707 * Allocate contiguous free clusters. 708 * 709 * pmp - mount point. 710 * start - preferred start of cluster chain. 711 * count - number of clusters requested. 712 * fillwith - put this value into the FAT entry for the 713 * last allocated cluster. 714 * retcluster - put the first allocated cluster's number here. 715 * got - how many clusters were actually allocated. 716 */ 717 int 718 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 719 u_long fillwith, u_long *retcluster, u_long *got) 720 { 721 int error; 722 723 MSDOSFS_LOCK_MP(pmp); 724 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 725 MSDOSFS_UNLOCK_MP(pmp); 726 return (error); 727 } 728 729 static int 730 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 731 u_long fillwith, u_long *retcluster, u_long *got) 732 { 733 u_long idx; 734 u_long len, newst, foundl, cn, l; 735 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 736 u_int map; 737 738 MSDOSFS_ASSERT_MP_LOCKED(pmp); 739 740 mprintf("clusteralloc(): find %lu clusters\n",count); 741 if (start) { 742 if ((len = chainlength(pmp, start, count)) >= count) 743 return (chainalloc(pmp, start, count, fillwith, 744 retcluster, got)); 745 } else 746 len = 0; 747 748 newst = pmp->pm_nxtfree; 749 foundl = 0; 750 751 for (cn = newst; cn <= pmp->pm_maxcluster;) { 752 idx = cn / N_INUSEBITS; 753 map = pmp->pm_inusemap[idx]; 754 map |= (1U << (cn % N_INUSEBITS)) - 1; 755 if (map != FULL_RUN) { 756 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 757 if ((l = chainlength(pmp, cn, count)) >= count) 758 return (chainalloc(pmp, cn, count, fillwith, 759 retcluster, got)); 760 if (l > foundl) { 761 foundcn = cn; 762 foundl = l; 763 } 764 cn += l + 1; 765 continue; 766 } 767 cn += N_INUSEBITS - cn % N_INUSEBITS; 768 } 769 for (cn = 0; cn < newst;) { 770 idx = cn / N_INUSEBITS; 771 map = pmp->pm_inusemap[idx]; 772 map |= (1U << (cn % N_INUSEBITS)) - 1; 773 if (map != FULL_RUN) { 774 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 775 if ((l = chainlength(pmp, cn, count)) >= count) 776 return (chainalloc(pmp, cn, count, fillwith, 777 retcluster, got)); 778 if (l > foundl) { 779 foundcn = cn; 780 foundl = l; 781 } 782 cn += l + 1; 783 continue; 784 } 785 cn += N_INUSEBITS - cn % N_INUSEBITS; 786 } 787 788 if (!foundl) 789 return (ENOSPC); 790 791 if (len) 792 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 793 else 794 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, 795 got)); 796 } 797 798 799 /* 800 * Free a chain of clusters. 801 * 802 * pmp - address of the msdosfs mount structure for the filesystem 803 * containing the cluster chain to be freed. 804 * startcluster - number of the 1st cluster in the chain of clusters to be 805 * freed. 806 */ 807 int 808 freeclusterchain(struct msdosfsmount *pmp, u_long cluster) 809 { 810 int error; 811 struct buf *bp = NULL; 812 u_long bn, bo, bsize, byteoffset; 813 u_long readcn, lbn = -1; 814 815 MSDOSFS_LOCK_MP(pmp); 816 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 817 byteoffset = FATOFS(pmp, cluster); 818 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 819 if (lbn != bn) { 820 if (bp) 821 updatefats(pmp, bp, lbn); 822 error = bread(pmp->pm_devvp, de_bn2doff(pmp, bn), 823 bsize, &bp); 824 if (error) { 825 brelse(bp); 826 MSDOSFS_UNLOCK_MP(pmp); 827 return (error); 828 } 829 lbn = bn; 830 } 831 usemap_free(pmp, cluster); 832 switch (pmp->pm_fatmask) { 833 case FAT12_MASK: 834 readcn = getushort(bp->b_data + bo); 835 if (cluster & 1) { 836 cluster = readcn >> 4; 837 readcn &= 0x000f; 838 readcn |= MSDOSFSFREE << 4; 839 } else { 840 cluster = readcn; 841 readcn &= 0xf000; 842 readcn |= MSDOSFSFREE & 0xfff; 843 } 844 putushort(bp->b_data + bo, readcn); 845 break; 846 case FAT16_MASK: 847 cluster = getushort(bp->b_data + bo); 848 putushort(bp->b_data + bo, MSDOSFSFREE); 849 break; 850 case FAT32_MASK: 851 cluster = getulong(bp->b_data + bo); 852 putulong(bp->b_data + bo, 853 (MSDOSFSFREE & FAT32_MASK) | 854 (cluster & ~FAT32_MASK)); 855 break; 856 } 857 cluster &= pmp->pm_fatmask; 858 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 859 cluster |= pmp->pm_fatmask; 860 } 861 if (bp) 862 updatefats(pmp, bp, bn); 863 MSDOSFS_UNLOCK_MP(pmp); 864 return (0); 865 } 866 867 /* 868 * Read in FAT blocks looking for free clusters. For every free cluster 869 * found turn off its corresponding bit in the pm_inusemap. 870 */ 871 int 872 fillinusemap(struct msdosfsmount *pmp) 873 { 874 struct buf *bp; 875 u_long bn, bo, bsize, byteoffset, cn, readcn; 876 int error; 877 878 MSDOSFS_ASSERT_MP_LOCKED(pmp); 879 bp = NULL; 880 881 /* 882 * Mark all clusters in use, we mark the free ones in the FAT scan 883 * loop further down. 884 */ 885 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 886 pmp->pm_inusemap[cn] = FULL_RUN; 887 888 /* 889 * Figure how many free clusters are in the filesystem by ripping 890 * through the FAT counting the number of entries whose content is 891 * zero. These represent free clusters. 892 */ 893 pmp->pm_freeclustercount = 0; 894 for (cn = 0; cn <= pmp->pm_maxcluster; cn++) { 895 byteoffset = FATOFS(pmp, cn); 896 bo = byteoffset % pmp->pm_fatblocksize; 897 if (bo == 0) { 898 /* Read new FAT block */ 899 if (bp != NULL) 900 brelse(bp); 901 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 902 error = bread(pmp->pm_devvp, de_bn2doff(pmp, bn), 903 bsize, &bp); 904 if (error != 0) { 905 brelse(bp); 906 return (error); 907 } 908 } 909 if (FAT32(pmp)) 910 readcn = getulong(bp->b_data + bo); 911 else 912 readcn = getushort(bp->b_data + bo); 913 if (FAT12(pmp) && (cn & 1)) 914 readcn >>= 4; 915 readcn &= pmp->pm_fatmask; 916 917 /* 918 * Check if the FAT ID matches the BPB's media descriptor and 919 * all other bits are set to 1. 920 */ 921 if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) | 922 pmp->pm_bpb.bpbMedia)) { 923 mprintf("fillinusemap(): Media descriptor in BPB " 924 "does not match FAT ID\n"); 925 brelse(bp); 926 return (EINVAL); 927 } else if (readcn == CLUST_FREE) 928 usemap_free(pmp, cn); 929 } 930 if (bp != NULL) 931 brelse(bp); 932 933 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster + 934 N_INUSEBITS) / N_INUSEBITS; cn++) 935 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 936 937 return (0); 938 } 939 940 /* 941 * Allocate a new cluster and chain it onto the end of the file. 942 * 943 * dep - the file to extend 944 * count - number of clusters to allocate 945 * bpp - where to return the address of the buf header for the first new 946 * file block 947 * ncp - where to put cluster number of the first newly allocated cluster 948 * If this pointer is 0, do not return the cluster number. 949 * flags - see fat.h 950 * 951 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 952 * the de_flag field of the denode and it does not change the de_FileSize 953 * field. This is left for the caller to do. 954 */ 955 int 956 extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp, 957 int flags) 958 { 959 int error; 960 u_long frcn; 961 u_long cn, got; 962 struct msdosfsmount *pmp = dep->de_pmp; 963 struct buf *bp; 964 965 /* 966 * Don't try to extend the root directory 967 */ 968 if (dep->de_StartCluster == MSDOSFSROOT 969 && (dep->de_Attributes & ATTR_DIRECTORY)) { 970 kprintf("extendfile(): attempt to extend root directory\n"); 971 return (ENOSPC); 972 } 973 974 /* 975 * If the "file's last cluster" cache entry is empty, and the file 976 * is not empty, then fill the cache entry by calling pcbmap(). 977 */ 978 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 979 dep->de_StartCluster != 0) { 980 error = pcbmap(dep, 0xffff, NULL, &cn, NULL); 981 /* we expect it to return E2BIG */ 982 if (error != E2BIG) 983 return (error); 984 } 985 986 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 987 dep->de_fc[FC_LASTFC].fc_frcn; 988 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 989 dep->de_fc[FC_LASTFC].fc_fsrcn; 990 while (count > 0) { 991 /* 992 * Allocate a new cluster chain and cat onto the end of the 993 * file. If the file is empty we make de_StartCluster point 994 * to the new block. Note that de_StartCluster being 0 is 995 * sufficient to be sure the file is empty since we exclude 996 * attempts to extend the root directory above, and the root 997 * dir is the only file with a startcluster of 0 that has 998 * blocks allocated (sort of). 999 */ 1000 if (dep->de_StartCluster == 0) 1001 cn = 0; 1002 else 1003 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1004 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1005 if (error) 1006 return (error); 1007 1008 count -= got; 1009 1010 /* 1011 * Give them the filesystem relative cluster number if they want 1012 * it. 1013 */ 1014 if (ncp) { 1015 *ncp = cn; 1016 ncp = NULL; 1017 } 1018 1019 if (dep->de_StartCluster == 0) { 1020 dep->de_StartCluster = cn; 1021 frcn = 0; 1022 } else { 1023 error = fatentry(FAT_SET, pmp, 1024 dep->de_fc[FC_LASTFC].fc_fsrcn, 1025 0, cn); 1026 if (error) { 1027 clusterfree(pmp, cn, NULL); 1028 return (error); 1029 } 1030 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1031 } 1032 1033 /* 1034 * Update the "last cluster of the file" entry in the 1035 * denode's FAT cache. 1036 */ 1037 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1038 1039 if (flags & DE_CLEAR) { 1040 while (got-- > 0) { 1041 /* 1042 * Get the buf header for the new block of the file. 1043 */ 1044 if (dep->de_Attributes & ATTR_DIRECTORY) { 1045 bp = getblk(pmp->pm_devvp, 1046 de_bn2doff(pmp, cntobn(pmp, cn)), 1047 pmp->pm_bpcluster, 0, 0); 1048 ++cn; 1049 } else { 1050 daddr_t dblkno; 1051 u_long findcn; 1052 1053 bp = getblk(DETOV(dep), 1054 de_cn2doff(pmp, frcn), 1055 pmp->pm_bpcluster, 0, 0); 1056 ++frcn; 1057 /* 1058 * Convert bio1 offset to file relative 1059 * cluster number. 1060 */ 1061 findcn = de_bn2cn(pmp, 1062 (daddr_t)(bp->b_bio1.bio_offset >> 1063 pmp->pm_bnshift)); 1064 /* 1065 * Do the bmap now, as in msdosfs_write 1066 */ 1067 if (pcbmap(dep, findcn, &dblkno, NULL, 1068 NULL)) { 1069 bp->b_bio2.bio_offset = NOOFFSET; 1070 } else { 1071 bp->b_bio2.bio_offset = de_bn2doff(pmp, dblkno); 1072 } 1073 if (bp->b_bio2.bio_offset == NOOFFSET) 1074 panic("extendfile: pcbmap"); 1075 } 1076 clrbuf(bp); 1077 if (bpp) { 1078 *bpp = bp; 1079 bpp = NULL; 1080 } else { 1081 bdwrite(bp); 1082 } 1083 } 1084 } 1085 } 1086 1087 return (0); 1088 } 1089 1090 /*- 1091 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1092 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1093 * this bit is not defined for FAT12 volumes, which are always assumed to 1094 * be clean. 1095 * 1096 * The fatentry() routine only works on cluster numbers that a file could 1097 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1098 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1099 * 1100 * Inputs: 1101 * pmp The MS-DOS volume to mark 1102 * dirty Non-zero if the volume should be marked dirty; zero if it 1103 * should be marked clean 1104 * 1105 * Result: 1106 * 0 Success 1107 * EROFS Volume is read-only 1108 * ? (other errors from called routines) 1109 */ 1110 int 1111 markvoldirty_upgrade(struct msdosfsmount *pmp, bool dirty, bool rw_upgrade) 1112 { 1113 struct buf *bp; 1114 u_long bn, bo, bsize, byteoffset, fatval; 1115 int error; 1116 1117 /* 1118 * FAT12 does not support a "clean" bit, so don't do anything for 1119 * FAT12. 1120 */ 1121 if (FAT12(pmp)) 1122 return (0); 1123 1124 /* 1125 * Can't change the bit on a read-only filesystem, except as part of 1126 * ro->rw upgrade. 1127 */ 1128 if ((pmp->pm_flags & MSDOSFSMNT_RONLY) != 0 && !rw_upgrade) 1129 return (EROFS); 1130 1131 /* 1132 * Fetch the block containing the FAT entry. It is given by the 1133 * pseudo-cluster 1. 1134 */ 1135 byteoffset = FATOFS(pmp, 1); 1136 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1137 error = bread(pmp->pm_devvp, de_bn2doff(pmp, bn), bsize, &bp); 1138 if (error) 1139 return (error); 1140 1141 /* 1142 * Get the current value of the FAT entry and set/clear the relevant 1143 * bit. Dirty means clear the "clean" bit; clean means set the 1144 * "clean" bit. 1145 */ 1146 if (FAT32(pmp)) { 1147 /* FAT32 uses bit 27. */ 1148 fatval = getulong(&bp->b_data[bo]); 1149 if (dirty) 1150 fatval &= 0xF7FFFFFF; 1151 else 1152 fatval |= 0x08000000; 1153 putulong(&bp->b_data[bo], fatval); 1154 } else { 1155 /* Must be FAT16; use bit 15. */ 1156 fatval = getushort(&bp->b_data[bo]); 1157 if (dirty) 1158 fatval &= 0x7FFF; 1159 else 1160 fatval |= 0x8000; 1161 putushort(&bp->b_data[bo], fatval); 1162 } 1163 #if 0 1164 /* 1165 * The concern here is that a devvp may be readonly, without reporting 1166 * itself as such through the usual channels. In that case, we'd like 1167 * it if attempting to mount msdosfs rw didn't panic the system. 1168 * 1169 * markvoldirty is invoked as the first write on backing devvps when 1170 * either msdosfs is mounted for the first time, or a ro mount is 1171 * upgraded to rw. 1172 * 1173 * In either event, if a write error occurs dirtying the volume: 1174 * - No user data has been permitted to be written to cache yet. 1175 * - We can abort the high-level operation (mount, or ro->rw) safely. 1176 * - We don't derive any benefit from leaving a zombie dirty buf in 1177 * the cache that can not be cleaned or evicted. 1178 * 1179 * So, mark B_INVALONERR to have bwrite() -> brelse() detect that 1180 * condition and force-invalidate our write to the block if it occurs. 1181 * 1182 * PR 210316 provides more context on the discovery and diagnosis of 1183 * the problem, as well as earlier attempts to solve it. 1184 */ 1185 bp->b_flags |= B_INVALONERR; 1186 #endif 1187 /* Write out the modified FAT block synchronously. */ 1188 return (bwrite(bp)); 1189 } 1190