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sys/fs/msdosfs/msdosfs_fat.c
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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] & 392 (1U << (cn % N_INUSEBITS))) == 0, 393 ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS, 394 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 395 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 396 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little")); 397 pmp->pm_freeclustercount--; 398 pmp->pm_flags |= MSDOSFS_FSIMOD; 399 } 400 401 static __inline void 402 usemap_free(struct msdosfsmount *pmp, u_long cn) 403 { 404 405 MSDOSFS_ASSERT_MP_LOCKED(pmp); 406 407 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 408 pmp->pm_maxcluster)); 409 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 410 ("usemap_free on ro msdosfs mount")); 411 pmp->pm_freeclustercount++; 412 pmp->pm_flags |= MSDOSFS_FSIMOD; 413 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & 414 (1U << (cn % N_INUSEBITS))) != 0, 415 ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS, 416 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 417 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1U << (cn % N_INUSEBITS)); 418 } 419 420 int 421 clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp) 422 { 423 int error; 424 u_long oldcn; 425 426 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 427 if (error) 428 return (error); 429 /* 430 * If the cluster was successfully marked free, then update 431 * the count of free clusters, and turn off the "allocated" 432 * bit in the "in use" cluster bit map. 433 */ 434 MSDOSFS_LOCK_MP(pmp); 435 usemap_free(pmp, cluster); 436 MSDOSFS_UNLOCK_MP(pmp); 437 if (oldcnp) 438 *oldcnp = oldcn; 439 return (0); 440 } 441 442 /* 443 * Get or Set or 'Get and Set' the cluster'th entry in the FAT. 444 * 445 * function - whether to get or set a FAT entry 446 * pmp - address of the msdosfsmount structure for the filesystem 447 * whose FAT is to be manipulated. 448 * cn - which cluster is of interest 449 * oldcontents - address of a word that is to receive the contents of the 450 * cluster'th entry if this is a get function 451 * newcontents - the new value to be written into the cluster'th element of 452 * the FAT if this is a set function. 453 * 454 * This function can also be used to free a cluster by setting the FAT entry 455 * for a cluster to 0. 456 * 457 * All copies of the FAT are updated if this is a set function. NOTE: If 458 * fatentry() marks a cluster as free it does not update the inusemap in 459 * the msdosfsmount structure. This is left to the caller. 460 */ 461 int 462 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, 463 u_long newcontents) 464 { 465 int error; 466 u_long readcn; 467 u_long bn, bo, bsize, byteoffset; 468 struct buf *bp; 469 470 #ifdef MSDOSFS_DEBUG 471 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 472 function, pmp, cn, oldcontents, newcontents); 473 #endif 474 475 #ifdef DIAGNOSTIC 476 /* 477 * Be sure they asked us to do something. 478 */ 479 if ((function & (FAT_SET | FAT_GET)) == 0) { 480 #ifdef MSDOSFS_DEBUG 481 printf("fatentry(): function code doesn't specify get or set\n"); 482 #endif 483 return (EINVAL); 484 } 485 486 /* 487 * If they asked us to return a cluster number but didn't tell us 488 * where to put it, give them an error. 489 */ 490 if ((function & FAT_GET) && oldcontents == NULL) { 491 #ifdef MSDOSFS_DEBUG 492 printf("fatentry(): get function with no place to put result\n"); 493 #endif 494 return (EINVAL); 495 } 496 #endif 497 498 /* 499 * Be sure the requested cluster is in the filesystem. 500 */ 501 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 502 return (EINVAL); 503 504 byteoffset = FATOFS(pmp, cn); 505 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 506 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 507 if (error) { 508 return (error); 509 } 510 511 if (function & FAT_GET) { 512 if (FAT32(pmp)) 513 readcn = getulong(bp->b_data + bo); 514 else 515 readcn = getushort(bp->b_data + bo); 516 if (FAT12(pmp) & (cn & 1)) 517 readcn >>= 4; 518 readcn &= pmp->pm_fatmask; 519 /* map reserved FAT entries to same values for all FATs */ 520 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 521 readcn |= ~pmp->pm_fatmask; 522 *oldcontents = readcn; 523 } 524 if (function & FAT_SET) { 525 switch (pmp->pm_fatmask) { 526 case FAT12_MASK: 527 readcn = getushort(bp->b_data + bo); 528 if (cn & 1) { 529 readcn &= 0x000f; 530 readcn |= newcontents << 4; 531 } else { 532 readcn &= 0xf000; 533 readcn |= newcontents & 0xfff; 534 } 535 putushort(bp->b_data + bo, readcn); 536 break; 537 case FAT16_MASK: 538 putushort(bp->b_data + bo, newcontents); 539 break; 540 case FAT32_MASK: 541 /* 542 * According to spec we have to retain the 543 * high order bits of the FAT entry. 544 */ 545 readcn = getulong(bp->b_data + bo); 546 readcn &= ~FAT32_MASK; 547 readcn |= newcontents & FAT32_MASK; 548 putulong(bp->b_data + bo, readcn); 549 break; 550 } 551 updatefats(pmp, bp, bn); 552 bp = NULL; 553 pmp->pm_fmod = 1; 554 } 555 if (bp) 556 brelse(bp); 557 return (0); 558 } 559 560 /* 561 * Update a contiguous cluster chain 562 * 563 * pmp - mount point 564 * start - first cluster of chain 565 * count - number of clusters in chain 566 * fillwith - what to write into FAT entry of last cluster 567 */ 568 static int 569 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) 570 { 571 int error; 572 u_long bn, bo, bsize, byteoffset, readcn, newc; 573 struct buf *bp; 574 575 #ifdef MSDOSFS_DEBUG 576 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 577 pmp, start, count, fillwith); 578 #endif 579 /* 580 * Be sure the clusters are in the filesystem. 581 */ 582 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 583 return (EINVAL); 584 585 while (count > 0) { 586 byteoffset = FATOFS(pmp, start); 587 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 588 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 589 if (error) { 590 return (error); 591 } 592 while (count > 0) { 593 start++; 594 newc = --count > 0 ? start : fillwith; 595 switch (pmp->pm_fatmask) { 596 case FAT12_MASK: 597 readcn = getushort(bp->b_data + bo); 598 if (start & 1) { 599 readcn &= 0xf000; 600 readcn |= newc & 0xfff; 601 } else { 602 readcn &= 0x000f; 603 readcn |= newc << 4; 604 } 605 putushort(bp->b_data + bo, readcn); 606 bo++; 607 if (!(start & 1)) 608 bo++; 609 break; 610 case FAT16_MASK: 611 putushort(bp->b_data + bo, newc); 612 bo += 2; 613 break; 614 case FAT32_MASK: 615 readcn = getulong(bp->b_data + bo); 616 readcn &= ~pmp->pm_fatmask; 617 readcn |= newc & pmp->pm_fatmask; 618 putulong(bp->b_data + bo, readcn); 619 bo += 4; 620 break; 621 } 622 if (bo >= bsize) 623 break; 624 } 625 updatefats(pmp, bp, bn); 626 } 627 pmp->pm_fmod = 1; 628 return (0); 629 } 630 631 /* 632 * Check the length of a free cluster chain starting at start. 633 * 634 * pmp - mount point 635 * start - start of chain 636 * count - maximum interesting length 637 */ 638 static int 639 chainlength(struct msdosfsmount *pmp, u_long start, u_long count) 640 { 641 u_long idx, max_idx; 642 u_int map; 643 u_long len; 644 645 MSDOSFS_ASSERT_MP_LOCKED(pmp); 646 647 if (start > pmp->pm_maxcluster) 648 return (0); 649 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 650 idx = start / N_INUSEBITS; 651 start %= N_INUSEBITS; 652 map = pmp->pm_inusemap[idx]; 653 map &= ~((1U << start) - 1); 654 if (map) { 655 len = ffs(map) - 1 - start; 656 len = MIN(len, count); 657 if (start + len > pmp->pm_maxcluster) 658 len = pmp->pm_maxcluster - start + 1; 659 return (len); 660 } 661 len = N_INUSEBITS - start; 662 if (len >= count) { 663 len = count; 664 if (start + len > pmp->pm_maxcluster) 665 len = pmp->pm_maxcluster - start + 1; 666 return (len); 667 } 668 while (++idx <= max_idx) { 669 if (len >= count) 670 break; 671 map = pmp->pm_inusemap[idx]; 672 if (map) { 673 len += ffs(map) - 1; 674 break; 675 } 676 len += N_INUSEBITS; 677 } 678 len = MIN(len, count); 679 if (start + len > pmp->pm_maxcluster) 680 len = pmp->pm_maxcluster - start + 1; 681 return (len); 682 } 683 684 /* 685 * Allocate contigous free clusters. 686 * 687 * pmp - mount point. 688 * start - start of cluster chain. 689 * count - number of clusters to allocate. 690 * fillwith - put this value into the FAT entry for the 691 * last allocated cluster. 692 * retcluster - put the first allocated cluster's number here. 693 * got - how many clusters were actually allocated. 694 */ 695 static int 696 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, 697 u_long fillwith, u_long *retcluster, u_long *got) 698 { 699 int error; 700 u_long cl, n; 701 702 MSDOSFS_ASSERT_MP_LOCKED(pmp); 703 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 704 ("chainalloc on ro msdosfs mount")); 705 706 for (cl = start, n = count; n-- > 0;) 707 usemap_alloc(pmp, cl++); 708 pmp->pm_nxtfree = start + count; 709 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 710 pmp->pm_nxtfree = CLUST_FIRST; 711 pmp->pm_flags |= MSDOSFS_FSIMOD; 712 error = fatchain(pmp, start, count, fillwith); 713 if (error != 0) { 714 for (cl = start, n = count; n-- > 0;) 715 usemap_free(pmp, cl++); 716 return (error); 717 } 718 #ifdef MSDOSFS_DEBUG 719 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 720 start, count); 721 #endif 722 if (retcluster) 723 *retcluster = start; 724 if (got) 725 *got = count; 726 return (0); 727 } 728 729 /* 730 * Allocate contiguous free clusters. 731 * 732 * pmp - mount point. 733 * start - preferred start of cluster chain. 734 * count - number of clusters requested. 735 * fillwith - put this value into the FAT entry for the 736 * last allocated cluster. 737 * retcluster - put the first allocated cluster's number here. 738 * got - how many clusters were actually allocated. 739 */ 740 int 741 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 742 u_long fillwith, u_long *retcluster, u_long *got) 743 { 744 int error; 745 746 MSDOSFS_LOCK_MP(pmp); 747 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 748 MSDOSFS_UNLOCK_MP(pmp); 749 return (error); 750 } 751 752 static int 753 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 754 u_long fillwith, u_long *retcluster, u_long *got) 755 { 756 u_long idx; 757 u_long len, newst, foundl, cn, l; 758 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 759 u_int map; 760 761 MSDOSFS_ASSERT_MP_LOCKED(pmp); 762 763 #ifdef MSDOSFS_DEBUG 764 printf("clusteralloc(): find %lu clusters\n", count); 765 #endif 766 if (start) { 767 if ((len = chainlength(pmp, start, count)) >= count) 768 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 769 } else 770 len = 0; 771 772 newst = pmp->pm_nxtfree; 773 foundl = 0; 774 775 for (cn = newst; cn <= pmp->pm_maxcluster;) { 776 idx = cn / N_INUSEBITS; 777 map = pmp->pm_inusemap[idx]; 778 map |= (1U << (cn % N_INUSEBITS)) - 1; 779 if (map != FULL_RUN) { 780 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 781 if ((l = chainlength(pmp, cn, count)) >= count) 782 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 783 if (l > foundl) { 784 foundcn = cn; 785 foundl = l; 786 } 787 cn += l + 1; 788 continue; 789 } 790 cn += N_INUSEBITS - cn % N_INUSEBITS; 791 } 792 for (cn = 0; cn < newst;) { 793 idx = cn / N_INUSEBITS; 794 map = pmp->pm_inusemap[idx]; 795 map |= (1U << (cn % N_INUSEBITS)) - 1; 796 if (map != FULL_RUN) { 797 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 798 if ((l = chainlength(pmp, cn, count)) >= count) 799 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 800 if (l > foundl) { 801 foundcn = cn; 802 foundl = l; 803 } 804 cn += l + 1; 805 continue; 806 } 807 cn += N_INUSEBITS - cn % N_INUSEBITS; 808 } 809 810 if (!foundl) 811 return (ENOSPC); 812 813 if (len) 814 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 815 else 816 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 817 } 818 819 /* 820 * Free a chain of clusters. 821 * 822 * pmp - address of the msdosfs mount structure for the filesystem 823 * containing the cluster chain to be freed. 824 * startcluster - number of the 1st cluster in the chain of clusters to be 825 * freed. 826 */ 827 int 828 freeclusterchain(struct msdosfsmount *pmp, u_long cluster) 829 { 830 int error; 831 struct buf *bp = NULL; 832 u_long bn, bo, bsize, byteoffset; 833 u_long readcn, lbn = -1; 834 835 MSDOSFS_LOCK_MP(pmp); 836 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 837 byteoffset = FATOFS(pmp, cluster); 838 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 839 if (lbn != bn) { 840 if (bp) 841 updatefats(pmp, bp, lbn); 842 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 843 if (error) { 844 MSDOSFS_UNLOCK_MP(pmp); 845 return (error); 846 } 847 lbn = bn; 848 } 849 usemap_free(pmp, cluster); 850 switch (pmp->pm_fatmask) { 851 case FAT12_MASK: 852 readcn = getushort(bp->b_data + bo); 853 if (cluster & 1) { 854 cluster = readcn >> 4; 855 readcn &= 0x000f; 856 readcn |= MSDOSFSFREE << 4; 857 } else { 858 cluster = readcn; 859 readcn &= 0xf000; 860 readcn |= MSDOSFSFREE & 0xfff; 861 } 862 putushort(bp->b_data + bo, readcn); 863 break; 864 case FAT16_MASK: 865 cluster = getushort(bp->b_data + bo); 866 putushort(bp->b_data + bo, MSDOSFSFREE); 867 break; 868 case FAT32_MASK: 869 cluster = getulong(bp->b_data + bo); 870 putulong(bp->b_data + bo, 871 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 872 break; 873 } 874 cluster &= pmp->pm_fatmask; 875 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 876 cluster |= pmp->pm_fatmask; 877 } 878 if (bp) 879 updatefats(pmp, bp, bn); 880 MSDOSFS_UNLOCK_MP(pmp); 881 return (0); 882 } 883 884 /* 885 * Read in FAT blocks looking for free clusters. For every free cluster 886 * found turn off its corresponding bit in the pm_inusemap. 887 */ 888 int 889 fillinusemap(struct msdosfsmount *pmp) 890 { 891 struct buf *bp; 892 u_long bn, bo, bsize, byteoffset, cn, readcn; 893 int error; 894 895 MSDOSFS_ASSERT_MP_LOCKED(pmp); 896 bp = NULL; 897 898 /* 899 * Mark all clusters in use, we mark the free ones in the FAT scan 900 * loop further down. 901 */ 902 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 903 pmp->pm_inusemap[cn] = FULL_RUN; 904 905 /* 906 * Figure how many free clusters are in the filesystem by ripping 907 * through the FAT counting the number of entries whose content is 908 * zero. These represent free clusters. 909 */ 910 pmp->pm_freeclustercount = 0; 911 for (cn = 0; cn <= pmp->pm_maxcluster; cn++) { 912 byteoffset = FATOFS(pmp, cn); 913 bo = byteoffset % pmp->pm_fatblocksize; 914 if (bo == 0) { 915 /* Read new FAT block */ 916 if (bp != NULL) 917 brelse(bp); 918 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 919 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 920 if (error != 0) 921 return (error); 922 } 923 if (FAT32(pmp)) 924 readcn = getulong(bp->b_data + bo); 925 else 926 readcn = getushort(bp->b_data + bo); 927 if (FAT12(pmp) && (cn & 1)) 928 readcn >>= 4; 929 readcn &= pmp->pm_fatmask; 930 931 /* 932 * Check if the FAT ID matches the BPB's media descriptor and 933 * all other bits are set to 1. 934 */ 935 if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) | 936 pmp->pm_bpb.bpbMedia)) { 937 #ifdef MSDOSFS_DEBUG 938 printf("mountmsdosfs(): Media descriptor in BPB" 939 "does not match FAT ID\n"); 940 #endif 941 brelse(bp); 942 return (EINVAL); 943 } else if (readcn == CLUST_FREE) 944 usemap_free(pmp, cn); 945 } 946 if (bp != NULL) 947 brelse(bp); 948 949 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster + 950 N_INUSEBITS) / N_INUSEBITS; cn++) 951 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 952 953 return (0); 954 } 955 956 /* 957 * Allocate a new cluster and chain it onto the end of the file. 958 * 959 * dep - the file to extend 960 * count - number of clusters to allocate 961 * bpp - where to return the address of the buf header for the first new 962 * file block 963 * ncp - where to put cluster number of the first newly allocated cluster 964 * If this pointer is 0, do not return the cluster number. 965 * flags - see fat.h 966 * 967 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 968 * the de_flag field of the denode and it does not change the de_FileSize 969 * field. This is left for the caller to do. 970 */ 971 int 972 extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp, 973 int flags) 974 { 975 int error; 976 u_long frcn; 977 u_long cn, got; 978 struct msdosfsmount *pmp = dep->de_pmp; 979 struct buf *bp; 980 daddr_t blkno; 981 982 /* 983 * Don't try to extend the root directory 984 */ 985 if (dep->de_StartCluster == MSDOSFSROOT 986 && (dep->de_Attributes & ATTR_DIRECTORY)) { 987 #ifdef MSDOSFS_DEBUG 988 printf("extendfile(): attempt to extend root directory\n"); 989 #endif 990 return (ENOSPC); 991 } 992 993 /* 994 * If the "file's last cluster" cache entry is empty, and the file 995 * is not empty, then fill the cache entry by calling pcbmap(). 996 */ 997 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 998 dep->de_StartCluster != 0) { 999 error = pcbmap(dep, 0xffff, 0, &cn, 0); 1000 /* we expect it to return E2BIG */ 1001 if (error != E2BIG) 1002 return (error); 1003 } 1004 1005 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 1006 dep->de_fc[FC_LASTFC].fc_frcn; 1007 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 1008 dep->de_fc[FC_LASTFC].fc_fsrcn; 1009 while (count > 0) { 1010 /* 1011 * Allocate a new cluster chain and cat onto the end of the 1012 * file. If the file is empty we make de_StartCluster point 1013 * to the new block. Note that de_StartCluster being 0 is 1014 * sufficient to be sure the file is empty since we exclude 1015 * attempts to extend the root directory above, and the root 1016 * dir is the only file with a startcluster of 0 that has 1017 * blocks allocated (sort of). 1018 */ 1019 if (dep->de_StartCluster == 0) 1020 cn = 0; 1021 else 1022 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1023 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1024 if (error) 1025 return (error); 1026 1027 count -= got; 1028 1029 /* 1030 * Give them the filesystem relative cluster number if they want 1031 * it. 1032 */ 1033 if (ncp) { 1034 *ncp = cn; 1035 ncp = NULL; 1036 } 1037 1038 if (dep->de_StartCluster == 0) { 1039 dep->de_StartCluster = cn; 1040 frcn = 0; 1041 } else { 1042 error = fatentry(FAT_SET, pmp, 1043 dep->de_fc[FC_LASTFC].fc_fsrcn, 1044 0, cn); 1045 if (error) { 1046 clusterfree(pmp, cn, NULL); 1047 return (error); 1048 } 1049 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1050 } 1051 1052 /* 1053 * Update the "last cluster of the file" entry in the 1054 * denode's FAT cache. 1055 */ 1056 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1057 1058 if (flags & DE_CLEAR) { 1059 while (got-- > 0) { 1060 /* 1061 * Get the buf header for the new block of the file. 1062 */ 1063 if (dep->de_Attributes & ATTR_DIRECTORY) 1064 bp = getblk(pmp->pm_devvp, 1065 cntobn(pmp, cn++), 1066 pmp->pm_bpcluster, 0, 0, 0); 1067 else { 1068 bp = getblk(DETOV(dep), 1069 frcn++, 1070 pmp->pm_bpcluster, 0, 0, 0); 1071 /* 1072 * Do the bmap now, as in msdosfs_write 1073 */ 1074 if (pcbmap(dep, 1075 bp->b_lblkno, 1076 &blkno, 0, 0)) 1077 bp->b_blkno = -1; 1078 if (bp->b_blkno == -1) 1079 panic("extendfile: pcbmap"); 1080 else 1081 bp->b_blkno = blkno; 1082 } 1083 clrbuf(bp); 1084 if (bpp) { 1085 *bpp = bp; 1086 bpp = NULL; 1087 } else { 1088 bdwrite(bp); 1089 } 1090 if (vm_page_count_severe() || 1091 buf_dirty_count_severe()) 1092 vn_fsync_buf(DETOV(dep), MNT_WAIT); 1093 } 1094 } 1095 } 1096 1097 return (0); 1098 } 1099 1100 /*- 1101 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1102 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1103 * this bit is not defined for FAT12 volumes, which are always assumed to 1104 * be clean. 1105 * 1106 * The fatentry() routine only works on cluster numbers that a file could 1107 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1108 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1109 * 1110 * Inputs: 1111 * pmp The MS-DOS volume to mark 1112 * dirty Non-zero if the volume should be marked dirty; zero if it 1113 * should be marked clean 1114 * 1115 * Result: 1116 * 0 Success 1117 * EROFS Volume is read-only 1118 * ? (other errors from called routines) 1119 */ 1120 int 1121 markvoldirty_upgrade(struct msdosfsmount *pmp, bool dirty, bool rw_upgrade) 1122 { 1123 struct buf *bp; 1124 u_long bn, bo, bsize, byteoffset, fatval; 1125 int error; 1126 1127 /* 1128 * FAT12 does not support a "clean" bit, so don't do anything for 1129 * FAT12. 1130 */ 1131 if (FAT12(pmp)) 1132 return (0); 1133 1134 /* 1135 * Can't change the bit on a read-only filesystem, except as part of 1136 * ro->rw upgrade. 1137 */ 1138 if ((pmp->pm_flags & MSDOSFSMNT_RONLY) != 0 && !rw_upgrade) 1139 return (EROFS); 1140 1141 /* 1142 * Fetch the block containing the FAT entry. It is given by the 1143 * pseudo-cluster 1. 1144 */ 1145 byteoffset = FATOFS(pmp, 1); 1146 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1147 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1148 if (error) 1149 return (error); 1150 1151 /* 1152 * Get the current value of the FAT entry and set/clear the relevant 1153 * bit. Dirty means clear the "clean" bit; clean means set the 1154 * "clean" bit. 1155 */ 1156 if (FAT32(pmp)) { 1157 /* FAT32 uses bit 27. */ 1158 fatval = getulong(&bp->b_data[bo]); 1159 if (dirty) 1160 fatval &= 0xF7FFFFFF; 1161 else 1162 fatval |= 0x08000000; 1163 putulong(&bp->b_data[bo], fatval); 1164 } else { 1165 /* Must be FAT16; use bit 15. */ 1166 fatval = getushort(&bp->b_data[bo]); 1167 if (dirty) 1168 fatval &= 0x7FFF; 1169 else 1170 fatval |= 0x8000; 1171 putushort(&bp->b_data[bo], fatval); 1172 } 1173 1174 /* 1175 * The concern here is that a devvp may be readonly, without reporting 1176 * itself as such through the usual channels. In that case, we'd like 1177 * it if attempting to mount msdosfs rw didn't panic the system. 1178 * 1179 * markvoldirty is invoked as the first write on backing devvps when 1180 * either msdosfs is mounted for the first time, or a ro mount is 1181 * upgraded to rw. 1182 * 1183 * In either event, if a write error occurs dirtying the volume: 1184 * - No user data has been permitted to be written to cache yet. 1185 * - We can abort the high-level operation (mount, or ro->rw) safely. 1186 * - We don't derive any benefit from leaving a zombie dirty buf in 1187 * the cache that can not be cleaned or evicted. 1188 * 1189 * So, mark B_INVALONERR to have bwrite() -> brelse() detect that 1190 * condition and force-invalidate our write to the block if it occurs. 1191 * 1192 * PR 210316 provides more context on the discovery and diagnosis of 1193 * the problem, as well as earlier attempts to solve it. 1194 */ 1195 bp->b_flags |= B_INVALONERR; 1196 1197 /* Write out the modified FAT block synchronously. */ 1198 return (bwrite(bp)); 1199 }
Cache object: f632f59a1dfee23e6bab38103f628546
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