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sys/fs/msdosfs/msdosfs_fat.c
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1 /* $FreeBSD: releng/11.0/sys/fs/msdosfs/msdosfs_fat.c 298806 2016-04-29 20:51:24Z pfg $ */ 2 /* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 ws Exp $ */ 3 4 /*- 5 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank. 6 * Copyright (C) 1994, 1995, 1997 TooLs GmbH. 7 * All rights reserved. 8 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below). 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by TooLs GmbH. 21 * 4. The name of TooLs GmbH may not be used to endorse or promote products 22 * derived from this software without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR 25 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 26 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 27 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 29 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 30 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 31 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 32 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 33 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 34 */ 35 /*- 36 * Written by Paul Popelka (paulp@uts.amdahl.com) 37 * 38 * You can do anything you want with this software, just don't say you wrote 39 * it, and don't remove this notice. 40 * 41 * This software is provided "as is". 42 * 43 * The author supplies this software to be publicly redistributed on the 44 * understanding that the author is not responsible for the correct 45 * functioning of this software in any circumstances and is not liable for 46 * any damages caused by this software. 47 * 48 * October 1992 49 */ 50 51 #include <sys/param.h> 52 #include <sys/systm.h> 53 #include <sys/buf.h> 54 #include <sys/mount.h> 55 #include <sys/vnode.h> 56 57 #include <fs/msdosfs/bpb.h> 58 #include <fs/msdosfs/direntry.h> 59 #include <fs/msdosfs/denode.h> 60 #include <fs/msdosfs/fat.h> 61 #include <fs/msdosfs/msdosfsmount.h> 62 63 static int chainalloc(struct msdosfsmount *pmp, u_long start, 64 u_long count, u_long fillwith, u_long *retcluster, 65 u_long *got); 66 static int chainlength(struct msdosfsmount *pmp, u_long start, 67 u_long count); 68 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 69 u_long *sizep, u_long *bop); 70 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 71 u_long fillwith); 72 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 73 u_long *fsrcnp); 74 static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 75 u_long fatbn); 76 static __inline void 77 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 78 static __inline void 79 usemap_free(struct msdosfsmount *pmp, u_long cn); 80 static int clusteralloc1(struct msdosfsmount *pmp, u_long start, 81 u_long count, u_long fillwith, u_long *retcluster, 82 u_long *got); 83 84 static void 85 fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep, 86 u_long *bop) 87 { 88 u_long bn, size; 89 90 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 91 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 92 * DEV_BSIZE; 93 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 94 95 if (bnp) 96 *bnp = bn; 97 if (sizep) 98 *sizep = size; 99 if (bop) 100 *bop = ofs % pmp->pm_fatblocksize; 101 } 102 103 /* 104 * Map the logical cluster number of a file into a physical disk sector 105 * that is filesystem relative. 106 * 107 * dep - address of denode representing the file of interest 108 * findcn - file relative cluster whose filesystem relative cluster number 109 * and/or block number are/is to be found 110 * bnp - address of where to place the filesystem relative block number. 111 * If this pointer is null then don't return this quantity. 112 * cnp - address of where to place the filesystem relative cluster number. 113 * If this pointer is null then don't return this quantity. 114 * sp - pointer to returned block size 115 * 116 * NOTE: Either bnp or cnp must be non-null. 117 * This function has one side effect. If the requested file relative cluster 118 * is beyond the end of file, then the actual number of clusters in the file 119 * is returned in *cnp. This is useful for determining how long a directory is. 120 * If cnp is null, nothing is returned. 121 */ 122 int 123 pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp) 124 { 125 int error; 126 u_long i; 127 u_long cn; 128 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 129 u_long byteoffset; 130 u_long bn; 131 u_long bo; 132 struct buf *bp = NULL; 133 u_long bp_bn = -1; 134 struct msdosfsmount *pmp = dep->de_pmp; 135 u_long bsize; 136 137 KASSERT(bnp != NULL || cnp != NULL || sp != NULL, 138 ("pcbmap: extra call")); 139 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap"); 140 141 cn = dep->de_StartCluster; 142 /* 143 * The "file" that makes up the root directory is contiguous, 144 * permanently allocated, of fixed size, and is not made up of 145 * clusters. If the cluster number is beyond the end of the root 146 * directory, then return the number of clusters in the file. 147 */ 148 if (cn == MSDOSFSROOT) { 149 if (dep->de_Attributes & ATTR_DIRECTORY) { 150 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 151 if (cnp) 152 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 153 return (E2BIG); 154 } 155 if (bnp) 156 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 157 if (cnp) 158 *cnp = MSDOSFSROOT; 159 if (sp) 160 *sp = min(pmp->pm_bpcluster, 161 dep->de_FileSize - de_cn2off(pmp, findcn)); 162 return (0); 163 } else { /* just an empty file */ 164 if (cnp) 165 *cnp = 0; 166 return (E2BIG); 167 } 168 } 169 170 /* 171 * All other files do I/O in cluster sized blocks 172 */ 173 if (sp) 174 *sp = pmp->pm_bpcluster; 175 176 /* 177 * Rummage around in the fat cache, maybe we can avoid tromping 178 * through every fat entry for the file. And, keep track of how far 179 * off the cache was from where we wanted to be. 180 */ 181 i = 0; 182 fc_lookup(dep, findcn, &i, &cn); 183 184 /* 185 * Handle all other files or directories the normal way. 186 */ 187 for (; i < findcn; i++) { 188 /* 189 * Stop with all reserved clusters, not just with EOF. 190 */ 191 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 192 goto hiteof; 193 byteoffset = FATOFS(pmp, cn); 194 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 195 if (bn != bp_bn) { 196 if (bp) 197 brelse(bp); 198 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 199 if (error) { 200 brelse(bp); 201 return (error); 202 } 203 bp_bn = bn; 204 } 205 prevcn = cn; 206 if (bo >= bsize) { 207 if (bp) 208 brelse(bp); 209 return (EIO); 210 } 211 if (FAT32(pmp)) 212 cn = getulong(&bp->b_data[bo]); 213 else 214 cn = getushort(&bp->b_data[bo]); 215 if (FAT12(pmp) && (prevcn & 1)) 216 cn >>= 4; 217 cn &= pmp->pm_fatmask; 218 219 /* 220 * Force the special cluster numbers 221 * to be the same for all cluster sizes 222 * to let the rest of msdosfs handle 223 * all cases the same. 224 */ 225 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 226 cn |= ~pmp->pm_fatmask; 227 } 228 229 if (!MSDOSFSEOF(pmp, cn)) { 230 if (bp) 231 brelse(bp); 232 if (bnp) 233 *bnp = cntobn(pmp, cn); 234 if (cnp) 235 *cnp = cn; 236 fc_setcache(dep, FC_LASTMAP, i, cn); 237 return (0); 238 } 239 240 hiteof:; 241 if (cnp) 242 *cnp = i; 243 if (bp) 244 brelse(bp); 245 /* update last file cluster entry in the fat cache */ 246 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 247 return (E2BIG); 248 } 249 250 /* 251 * Find the closest entry in the fat cache to the cluster we are looking 252 * for. 253 */ 254 static void 255 fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp) 256 { 257 int i; 258 u_long cn; 259 struct fatcache *closest = NULL; 260 261 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup"); 262 263 for (i = 0; i < FC_SIZE; i++) { 264 cn = dep->de_fc[i].fc_frcn; 265 if (cn != FCE_EMPTY && cn <= findcn) { 266 if (closest == NULL || cn > closest->fc_frcn) 267 closest = &dep->de_fc[i]; 268 } 269 } 270 if (closest) { 271 *frcnp = closest->fc_frcn; 272 *fsrcnp = closest->fc_fsrcn; 273 } 274 } 275 276 /* 277 * Purge the fat cache in denode dep of all entries relating to file 278 * relative cluster frcn and beyond. 279 */ 280 void 281 fc_purge(struct denode *dep, u_int frcn) 282 { 283 int i; 284 struct fatcache *fcp; 285 286 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge"); 287 288 fcp = dep->de_fc; 289 for (i = 0; i < FC_SIZE; i++, fcp++) { 290 if (fcp->fc_frcn >= frcn) 291 fcp->fc_frcn = FCE_EMPTY; 292 } 293 } 294 295 /* 296 * Update the fat. 297 * If mirroring the fat, update all copies, with the first copy as last. 298 * Else update only the current fat (ignoring the others). 299 * 300 * pmp - msdosfsmount structure for filesystem to update 301 * bp - addr of modified fat block 302 * fatbn - block number relative to begin of filesystem of the modified fat block. 303 */ 304 static void 305 updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn) 306 { 307 struct buf *bpn; 308 int cleanfat, i; 309 310 #ifdef MSDOSFS_DEBUG 311 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 312 #endif 313 314 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 315 /* 316 * Now copy the block(s) of the modified fat to the other copies of 317 * the fat and write them out. This is faster than reading in the 318 * other fats and then writing them back out. This could tie up 319 * the fat for quite a while. Preventing others from accessing it. 320 * To prevent us from going after the fat quite so much we use 321 * delayed writes, unless they specfied "synchronous" when the 322 * filesystem was mounted. If synch is asked for then use 323 * bwrite()'s and really slow things down. 324 */ 325 if (fatbn != pmp->pm_fatblk || FAT12(pmp)) 326 cleanfat = 0; 327 else if (FAT16(pmp)) 328 cleanfat = 16; 329 else 330 cleanfat = 32; 331 for (i = 1; i < pmp->pm_FATs; i++) { 332 fatbn += pmp->pm_FATsecs; 333 /* getblk() never fails */ 334 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 335 0, 0, 0); 336 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 337 /* Force the clean bit on in the other copies. */ 338 if (cleanfat == 16) 339 ((u_int8_t *)bpn->b_data)[3] |= 0x80; 340 else if (cleanfat == 32) 341 ((u_int8_t *)bpn->b_data)[7] |= 0x08; 342 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 343 bwrite(bpn); 344 else 345 bdwrite(bpn); 346 } 347 } 348 349 /* 350 * Write out the first (or current) fat last. 351 */ 352 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 353 bwrite(bp); 354 else 355 bdwrite(bp); 356 } 357 358 /* 359 * Updating entries in 12 bit fats is a pain in the butt. 360 * 361 * The following picture shows where nibbles go when moving from a 12 bit 362 * cluster number into the appropriate bytes in the FAT. 363 * 364 * byte m byte m+1 byte m+2 365 * +----+----+ +----+----+ +----+----+ 366 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 367 * +----+----+ +----+----+ +----+----+ 368 * 369 * +----+----+----+ +----+----+----+ 370 * | 3 0 1 | | 4 5 2 | 371 * +----+----+----+ +----+----+----+ 372 * cluster n cluster n+1 373 * 374 * Where n is even. m = n + (n >> 2) 375 * 376 */ 377 static __inline void 378 usemap_alloc(struct msdosfsmount *pmp, u_long cn) 379 { 380 381 MSDOSFS_ASSERT_MP_LOCKED(pmp); 382 383 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 384 ("usemap_alloc on ro msdosfs mount")); 385 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 386 == 0, ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS, 387 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 388 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 389 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little")); 390 pmp->pm_freeclustercount--; 391 pmp->pm_flags |= MSDOSFS_FSIMOD; 392 } 393 394 static __inline void 395 usemap_free(struct msdosfsmount *pmp, u_long cn) 396 { 397 398 MSDOSFS_ASSERT_MP_LOCKED(pmp); 399 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 400 ("usemap_free on ro msdosfs mount")); 401 pmp->pm_freeclustercount++; 402 pmp->pm_flags |= MSDOSFS_FSIMOD; 403 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 404 != 0, ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS, 405 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 406 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 407 } 408 409 int 410 clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp) 411 { 412 int error; 413 u_long oldcn; 414 415 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 416 if (error) 417 return (error); 418 /* 419 * If the cluster was successfully marked free, then update 420 * the count of free clusters, and turn off the "allocated" 421 * bit in the "in use" cluster bit map. 422 */ 423 MSDOSFS_LOCK_MP(pmp); 424 usemap_free(pmp, cluster); 425 MSDOSFS_UNLOCK_MP(pmp); 426 if (oldcnp) 427 *oldcnp = oldcn; 428 return (0); 429 } 430 431 /* 432 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 433 * 434 * function - whether to get or set a fat entry 435 * pmp - address of the msdosfsmount structure for the filesystem 436 * whose fat is to be manipulated. 437 * cn - which cluster is of interest 438 * oldcontents - address of a word that is to receive the contents of the 439 * cluster'th entry if this is a get function 440 * newcontents - the new value to be written into the cluster'th element of 441 * the fat if this is a set function. 442 * 443 * This function can also be used to free a cluster by setting the fat entry 444 * for a cluster to 0. 445 * 446 * All copies of the fat are updated if this is a set function. NOTE: If 447 * fatentry() marks a cluster as free it does not update the inusemap in 448 * the msdosfsmount structure. This is left to the caller. 449 */ 450 int 451 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, 452 u_long newcontents) 453 { 454 int error; 455 u_long readcn; 456 u_long bn, bo, bsize, byteoffset; 457 struct buf *bp; 458 459 #ifdef MSDOSFS_DEBUG 460 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 461 function, pmp, cn, oldcontents, newcontents); 462 #endif 463 464 #ifdef DIAGNOSTIC 465 /* 466 * Be sure they asked us to do something. 467 */ 468 if ((function & (FAT_SET | FAT_GET)) == 0) { 469 #ifdef MSDOSFS_DEBUG 470 printf("fatentry(): function code doesn't specify get or set\n"); 471 #endif 472 return (EINVAL); 473 } 474 475 /* 476 * If they asked us to return a cluster number but didn't tell us 477 * where to put it, give them an error. 478 */ 479 if ((function & FAT_GET) && oldcontents == NULL) { 480 #ifdef MSDOSFS_DEBUG 481 printf("fatentry(): get function with no place to put result\n"); 482 #endif 483 return (EINVAL); 484 } 485 #endif 486 487 /* 488 * Be sure the requested cluster is in the filesystem. 489 */ 490 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 491 return (EINVAL); 492 493 byteoffset = FATOFS(pmp, cn); 494 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 495 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 496 if (error) { 497 brelse(bp); 498 return (error); 499 } 500 501 if (function & FAT_GET) { 502 if (FAT32(pmp)) 503 readcn = getulong(&bp->b_data[bo]); 504 else 505 readcn = getushort(&bp->b_data[bo]); 506 if (FAT12(pmp) & (cn & 1)) 507 readcn >>= 4; 508 readcn &= pmp->pm_fatmask; 509 /* map reserved fat entries to same values for all fats */ 510 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 511 readcn |= ~pmp->pm_fatmask; 512 *oldcontents = readcn; 513 } 514 if (function & FAT_SET) { 515 switch (pmp->pm_fatmask) { 516 case FAT12_MASK: 517 readcn = getushort(&bp->b_data[bo]); 518 if (cn & 1) { 519 readcn &= 0x000f; 520 readcn |= newcontents << 4; 521 } else { 522 readcn &= 0xf000; 523 readcn |= newcontents & 0xfff; 524 } 525 putushort(&bp->b_data[bo], readcn); 526 break; 527 case FAT16_MASK: 528 putushort(&bp->b_data[bo], newcontents); 529 break; 530 case FAT32_MASK: 531 /* 532 * According to spec we have to retain the 533 * high order bits of the fat entry. 534 */ 535 readcn = getulong(&bp->b_data[bo]); 536 readcn &= ~FAT32_MASK; 537 readcn |= newcontents & FAT32_MASK; 538 putulong(&bp->b_data[bo], readcn); 539 break; 540 } 541 updatefats(pmp, bp, bn); 542 bp = NULL; 543 pmp->pm_fmod = 1; 544 } 545 if (bp) 546 brelse(bp); 547 return (0); 548 } 549 550 /* 551 * Update a contiguous cluster chain 552 * 553 * pmp - mount point 554 * start - first cluster of chain 555 * count - number of clusters in chain 556 * fillwith - what to write into fat entry of last cluster 557 */ 558 static int 559 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) 560 { 561 int error; 562 u_long bn, bo, bsize, byteoffset, readcn, newc; 563 struct buf *bp; 564 565 #ifdef MSDOSFS_DEBUG 566 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 567 pmp, start, count, fillwith); 568 #endif 569 /* 570 * Be sure the clusters are in the filesystem. 571 */ 572 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 573 return (EINVAL); 574 575 while (count > 0) { 576 byteoffset = FATOFS(pmp, start); 577 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 578 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 579 if (error) { 580 brelse(bp); 581 return (error); 582 } 583 while (count > 0) { 584 start++; 585 newc = --count > 0 ? start : fillwith; 586 switch (pmp->pm_fatmask) { 587 case FAT12_MASK: 588 readcn = getushort(&bp->b_data[bo]); 589 if (start & 1) { 590 readcn &= 0xf000; 591 readcn |= newc & 0xfff; 592 } else { 593 readcn &= 0x000f; 594 readcn |= newc << 4; 595 } 596 putushort(&bp->b_data[bo], readcn); 597 bo++; 598 if (!(start & 1)) 599 bo++; 600 break; 601 case FAT16_MASK: 602 putushort(&bp->b_data[bo], newc); 603 bo += 2; 604 break; 605 case FAT32_MASK: 606 readcn = getulong(&bp->b_data[bo]); 607 readcn &= ~pmp->pm_fatmask; 608 readcn |= newc & pmp->pm_fatmask; 609 putulong(&bp->b_data[bo], readcn); 610 bo += 4; 611 break; 612 } 613 if (bo >= bsize) 614 break; 615 } 616 updatefats(pmp, bp, bn); 617 } 618 pmp->pm_fmod = 1; 619 return (0); 620 } 621 622 /* 623 * Check the length of a free cluster chain starting at start. 624 * 625 * pmp - mount point 626 * start - start of chain 627 * count - maximum interesting length 628 */ 629 static int 630 chainlength(struct msdosfsmount *pmp, u_long start, u_long count) 631 { 632 u_long idx, max_idx; 633 u_int map; 634 u_long len; 635 636 MSDOSFS_ASSERT_MP_LOCKED(pmp); 637 638 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 639 idx = start / N_INUSEBITS; 640 start %= N_INUSEBITS; 641 map = pmp->pm_inusemap[idx]; 642 map &= ~((1 << start) - 1); 643 if (map) { 644 len = ffs(map) - 1 - start; 645 return (len > count ? count : len); 646 } 647 len = N_INUSEBITS - start; 648 if (len >= count) 649 return (count); 650 while (++idx <= max_idx) { 651 if (len >= count) 652 break; 653 map = pmp->pm_inusemap[idx]; 654 if (map) { 655 len += ffs(map) - 1; 656 break; 657 } 658 len += N_INUSEBITS; 659 } 660 return (len > count ? count : len); 661 } 662 663 /* 664 * Allocate contigous free clusters. 665 * 666 * pmp - mount point. 667 * start - start of cluster chain. 668 * count - number of clusters to allocate. 669 * fillwith - put this value into the fat entry for the 670 * last allocated cluster. 671 * retcluster - put the first allocated cluster's number here. 672 * got - how many clusters were actually allocated. 673 */ 674 static int 675 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, 676 u_long fillwith, u_long *retcluster, u_long *got) 677 { 678 int error; 679 u_long cl, n; 680 681 MSDOSFS_ASSERT_MP_LOCKED(pmp); 682 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 683 ("chainalloc on ro msdosfs mount")); 684 685 for (cl = start, n = count; n-- > 0;) 686 usemap_alloc(pmp, cl++); 687 pmp->pm_nxtfree = start + count; 688 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 689 pmp->pm_nxtfree = CLUST_FIRST; 690 pmp->pm_flags |= MSDOSFS_FSIMOD; 691 error = fatchain(pmp, start, count, fillwith); 692 if (error != 0) 693 return (error); 694 #ifdef MSDOSFS_DEBUG 695 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 696 start, count); 697 #endif 698 if (retcluster) 699 *retcluster = start; 700 if (got) 701 *got = count; 702 return (0); 703 } 704 705 /* 706 * Allocate contiguous free clusters. 707 * 708 * pmp - mount point. 709 * start - preferred start of cluster chain. 710 * count - number of clusters requested. 711 * fillwith - put this value into the fat entry for the 712 * last allocated cluster. 713 * retcluster - put the first allocated cluster's number here. 714 * got - how many clusters were actually allocated. 715 */ 716 int 717 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 718 u_long fillwith, u_long *retcluster, u_long *got) 719 { 720 int error; 721 722 MSDOSFS_LOCK_MP(pmp); 723 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 724 MSDOSFS_UNLOCK_MP(pmp); 725 return (error); 726 } 727 728 static int 729 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 730 u_long fillwith, u_long *retcluster, u_long *got) 731 { 732 u_long idx; 733 u_long len, newst, foundl, cn, l; 734 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 735 u_int map; 736 737 MSDOSFS_ASSERT_MP_LOCKED(pmp); 738 739 #ifdef MSDOSFS_DEBUG 740 printf("clusteralloc(): find %lu clusters\n", count); 741 #endif 742 if (start) { 743 if ((len = chainlength(pmp, start, count)) >= count) 744 return (chainalloc(pmp, start, count, fillwith, 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 |= (1 << (cn % N_INUSEBITS)) - 1; 755 if (map != (u_int)-1) { 756 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 757 if ((l = chainlength(pmp, cn, count)) >= count) 758 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 759 if (l > foundl) { 760 foundcn = cn; 761 foundl = l; 762 } 763 cn += l + 1; 764 continue; 765 } 766 cn += N_INUSEBITS - cn % N_INUSEBITS; 767 } 768 for (cn = 0; cn < newst;) { 769 idx = cn / N_INUSEBITS; 770 map = pmp->pm_inusemap[idx]; 771 map |= (1 << (cn % N_INUSEBITS)) - 1; 772 if (map != (u_int)-1) { 773 cn = idx * N_INUSEBITS + ffs(map^(u_int)-1) - 1; 774 if ((l = chainlength(pmp, cn, count)) >= count) 775 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 776 if (l > foundl) { 777 foundcn = cn; 778 foundl = l; 779 } 780 cn += l + 1; 781 continue; 782 } 783 cn += N_INUSEBITS - cn % N_INUSEBITS; 784 } 785 786 if (!foundl) 787 return (ENOSPC); 788 789 if (len) 790 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 791 else 792 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 793 } 794 795 796 /* 797 * Free a chain of clusters. 798 * 799 * pmp - address of the msdosfs mount structure for the filesystem 800 * containing the cluster chain to be freed. 801 * startcluster - number of the 1st cluster in the chain of clusters to be 802 * freed. 803 */ 804 int 805 freeclusterchain(struct msdosfsmount *pmp, u_long cluster) 806 { 807 int error; 808 struct buf *bp = NULL; 809 u_long bn, bo, bsize, byteoffset; 810 u_long readcn, lbn = -1; 811 812 MSDOSFS_LOCK_MP(pmp); 813 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 814 byteoffset = FATOFS(pmp, cluster); 815 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 816 if (lbn != bn) { 817 if (bp) 818 updatefats(pmp, bp, lbn); 819 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 820 if (error) { 821 brelse(bp); 822 MSDOSFS_UNLOCK_MP(pmp); 823 return (error); 824 } 825 lbn = bn; 826 } 827 usemap_free(pmp, cluster); 828 switch (pmp->pm_fatmask) { 829 case FAT12_MASK: 830 readcn = getushort(&bp->b_data[bo]); 831 if (cluster & 1) { 832 cluster = readcn >> 4; 833 readcn &= 0x000f; 834 readcn |= MSDOSFSFREE << 4; 835 } else { 836 cluster = readcn; 837 readcn &= 0xf000; 838 readcn |= MSDOSFSFREE & 0xfff; 839 } 840 putushort(&bp->b_data[bo], readcn); 841 break; 842 case FAT16_MASK: 843 cluster = getushort(&bp->b_data[bo]); 844 putushort(&bp->b_data[bo], MSDOSFSFREE); 845 break; 846 case FAT32_MASK: 847 cluster = getulong(&bp->b_data[bo]); 848 putulong(&bp->b_data[bo], 849 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 850 break; 851 } 852 cluster &= pmp->pm_fatmask; 853 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 854 cluster |= pmp->pm_fatmask; 855 } 856 if (bp) 857 updatefats(pmp, bp, bn); 858 MSDOSFS_UNLOCK_MP(pmp); 859 return (0); 860 } 861 862 /* 863 * Read in fat blocks looking for free clusters. For every free cluster 864 * found turn off its corresponding bit in the pm_inusemap. 865 */ 866 int 867 fillinusemap(struct msdosfsmount *pmp) 868 { 869 struct buf *bp = NULL; 870 u_long cn, readcn; 871 int error; 872 u_long bn, bo, bsize, byteoffset; 873 874 MSDOSFS_ASSERT_MP_LOCKED(pmp); 875 876 /* 877 * Mark all clusters in use, we mark the free ones in the fat scan 878 * loop further down. 879 */ 880 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 881 pmp->pm_inusemap[cn] = (u_int)-1; 882 883 /* 884 * Figure how many free clusters are in the filesystem by ripping 885 * through the fat counting the number of entries whose content is 886 * zero. These represent free clusters. 887 */ 888 pmp->pm_freeclustercount = 0; 889 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 890 byteoffset = FATOFS(pmp, cn); 891 bo = byteoffset % pmp->pm_fatblocksize; 892 if (!bo || !bp) { 893 /* Read new FAT block */ 894 if (bp) 895 brelse(bp); 896 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 897 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 898 if (error) { 899 brelse(bp); 900 return (error); 901 } 902 } 903 if (FAT32(pmp)) 904 readcn = getulong(&bp->b_data[bo]); 905 else 906 readcn = getushort(&bp->b_data[bo]); 907 if (FAT12(pmp) && (cn & 1)) 908 readcn >>= 4; 909 readcn &= pmp->pm_fatmask; 910 911 if (readcn == 0) 912 usemap_free(pmp, cn); 913 } 914 if (bp != NULL) 915 brelse(bp); 916 return (0); 917 } 918 919 /* 920 * Allocate a new cluster and chain it onto the end of the file. 921 * 922 * dep - the file to extend 923 * count - number of clusters to allocate 924 * bpp - where to return the address of the buf header for the first new 925 * file block 926 * ncp - where to put cluster number of the first newly allocated cluster 927 * If this pointer is 0, do not return the cluster number. 928 * flags - see fat.h 929 * 930 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 931 * the de_flag field of the denode and it does not change the de_FileSize 932 * field. This is left for the caller to do. 933 */ 934 int 935 extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp, 936 int flags) 937 { 938 int error; 939 u_long frcn; 940 u_long cn, got; 941 struct msdosfsmount *pmp = dep->de_pmp; 942 struct buf *bp; 943 daddr_t blkno; 944 945 /* 946 * Don't try to extend the root directory 947 */ 948 if (dep->de_StartCluster == MSDOSFSROOT 949 && (dep->de_Attributes & ATTR_DIRECTORY)) { 950 #ifdef MSDOSFS_DEBUG 951 printf("extendfile(): attempt to extend root directory\n"); 952 #endif 953 return (ENOSPC); 954 } 955 956 /* 957 * If the "file's last cluster" cache entry is empty, and the file 958 * is not empty, then fill the cache entry by calling pcbmap(). 959 */ 960 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 961 dep->de_StartCluster != 0) { 962 error = pcbmap(dep, 0xffff, 0, &cn, 0); 963 /* we expect it to return E2BIG */ 964 if (error != E2BIG) 965 return (error); 966 } 967 968 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 969 dep->de_fc[FC_LASTFC].fc_frcn; 970 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 971 dep->de_fc[FC_LASTFC].fc_fsrcn; 972 while (count > 0) { 973 /* 974 * Allocate a new cluster chain and cat onto the end of the 975 * file. * If the file is empty we make de_StartCluster point 976 * to the new block. Note that de_StartCluster being 0 is 977 * sufficient to be sure the file is empty since we exclude 978 * attempts to extend the root directory above, and the root 979 * dir is the only file with a startcluster of 0 that has 980 * blocks allocated (sort of). 981 */ 982 if (dep->de_StartCluster == 0) 983 cn = 0; 984 else 985 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 986 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 987 if (error) 988 return (error); 989 990 count -= got; 991 992 /* 993 * Give them the filesystem relative cluster number if they want 994 * it. 995 */ 996 if (ncp) { 997 *ncp = cn; 998 ncp = NULL; 999 } 1000 1001 if (dep->de_StartCluster == 0) { 1002 dep->de_StartCluster = cn; 1003 frcn = 0; 1004 } else { 1005 error = fatentry(FAT_SET, pmp, 1006 dep->de_fc[FC_LASTFC].fc_fsrcn, 1007 0, cn); 1008 if (error) { 1009 clusterfree(pmp, cn, NULL); 1010 return (error); 1011 } 1012 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1013 } 1014 1015 /* 1016 * Update the "last cluster of the file" entry in the denode's fat 1017 * cache. 1018 */ 1019 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1020 1021 if (flags & DE_CLEAR) { 1022 while (got-- > 0) { 1023 /* 1024 * Get the buf header for the new block of the file. 1025 */ 1026 if (dep->de_Attributes & ATTR_DIRECTORY) 1027 bp = getblk(pmp->pm_devvp, 1028 cntobn(pmp, cn++), 1029 pmp->pm_bpcluster, 0, 0, 0); 1030 else { 1031 bp = getblk(DETOV(dep), 1032 frcn++, 1033 pmp->pm_bpcluster, 0, 0, 0); 1034 /* 1035 * Do the bmap now, as in msdosfs_write 1036 */ 1037 if (pcbmap(dep, 1038 bp->b_lblkno, 1039 &blkno, 0, 0)) 1040 bp->b_blkno = -1; 1041 if (bp->b_blkno == -1) 1042 panic("extendfile: pcbmap"); 1043 else 1044 bp->b_blkno = blkno; 1045 } 1046 vfs_bio_clrbuf(bp); 1047 if (bpp) { 1048 *bpp = bp; 1049 bpp = NULL; 1050 } else 1051 bdwrite(bp); 1052 } 1053 } 1054 } 1055 1056 return (0); 1057 } 1058 1059 /*- 1060 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1061 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1062 * this bit is not defined for FAT12 volumes, which are always assumed to 1063 * be clean. 1064 * 1065 * The fatentry() routine only works on cluster numbers that a file could 1066 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1067 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1068 * 1069 * Inputs: 1070 * pmp The MS-DOS volume to mark 1071 * dirty Non-zero if the volume should be marked dirty; zero if it 1072 * should be marked clean 1073 * 1074 * Result: 1075 * 0 Success 1076 * EROFS Volume is read-only 1077 * ? (other errors from called routines) 1078 */ 1079 int 1080 markvoldirty(struct msdosfsmount *pmp, int dirty) 1081 { 1082 struct buf *bp; 1083 u_long bn, bo, bsize, byteoffset, fatval; 1084 int error; 1085 1086 /* 1087 * FAT12 does not support a "clean" bit, so don't do anything for 1088 * FAT12. 1089 */ 1090 if (FAT12(pmp)) 1091 return (0); 1092 1093 /* Can't change the bit on a read-only filesystem. */ 1094 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1095 return (EROFS); 1096 1097 /* 1098 * Fetch the block containing the FAT entry. It is given by the 1099 * pseudo-cluster 1. 1100 */ 1101 byteoffset = FATOFS(pmp, 1); 1102 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1103 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1104 if (error) { 1105 brelse(bp); 1106 return (error); 1107 } 1108 1109 /* 1110 * Get the current value of the FAT entry and set/clear the relevant 1111 * bit. Dirty means clear the "clean" bit; clean means set the 1112 * "clean" bit. 1113 */ 1114 if (FAT32(pmp)) { 1115 /* FAT32 uses bit 27. */ 1116 fatval = getulong(&bp->b_data[bo]); 1117 if (dirty) 1118 fatval &= 0xF7FFFFFF; 1119 else 1120 fatval |= 0x08000000; 1121 putulong(&bp->b_data[bo], fatval); 1122 } else { 1123 /* Must be FAT16; use bit 15. */ 1124 fatval = getushort(&bp->b_data[bo]); 1125 if (dirty) 1126 fatval &= 0x7FFF; 1127 else 1128 fatval |= 0x8000; 1129 putushort(&bp->b_data[bo], fatval); 1130 } 1131 1132 /* Write out the modified FAT block synchronously. */ 1133 return (bwrite(bp)); 1134 }
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