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