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sys/fs/msdosfs/msdosfs_fat.c
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1 /* $FreeBSD: releng/10.4/sys/fs/msdosfs/msdosfs_fat.c 308551 2016-11-11 20:06:07Z kib $ */ 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 #define FULL_RUN ((u_int)0xffffffff) 64 65 static int chainalloc(struct msdosfsmount *pmp, u_long start, 66 u_long count, u_long fillwith, u_long *retcluster, 67 u_long *got); 68 static int chainlength(struct msdosfsmount *pmp, u_long start, 69 u_long count); 70 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 71 u_long *sizep, u_long *bop); 72 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 73 u_long fillwith); 74 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 75 u_long *fsrcnp); 76 static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 77 u_long fatbn); 78 static __inline void 79 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 80 static __inline void 81 usemap_free(struct msdosfsmount *pmp, u_long cn); 82 static int clusteralloc1(struct msdosfsmount *pmp, u_long start, 83 u_long count, u_long fillwith, u_long *retcluster, 84 u_long *got); 85 86 static void 87 fatblock(pmp, ofs, bnp, sizep, bop) 88 struct msdosfsmount *pmp; 89 u_long ofs; 90 u_long *bnp; 91 u_long *sizep; 92 u_long *bop; 93 { 94 u_long bn, size; 95 96 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 97 size = min(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 98 * DEV_BSIZE; 99 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 100 101 if (bnp) 102 *bnp = bn; 103 if (sizep) 104 *sizep = size; 105 if (bop) 106 *bop = ofs % pmp->pm_fatblocksize; 107 } 108 109 /* 110 * Map the logical cluster number of a file into a physical disk sector 111 * that is filesystem relative. 112 * 113 * dep - address of denode representing the file of interest 114 * findcn - file relative cluster whose filesystem relative cluster number 115 * and/or block number are/is to be found 116 * bnp - address of where to place the filesystem relative block number. 117 * If this pointer is null then don't return this quantity. 118 * cnp - address of where to place the filesystem relative cluster number. 119 * If this pointer is null then don't return this quantity. 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(dep, findcn, bnp, cnp, sp) 129 struct denode *dep; 130 u_long findcn; /* file relative cluster to get */ 131 daddr_t *bnp; /* returned filesys relative blk number */ 132 u_long *cnp; /* returned cluster number */ 133 int *sp; /* returned block size */ 134 { 135 int error; 136 u_long i; 137 u_long cn; 138 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 139 u_long byteoffset; 140 u_long bn; 141 u_long bo; 142 struct buf *bp = NULL; 143 u_long bp_bn = -1; 144 struct msdosfsmount *pmp = dep->de_pmp; 145 u_long bsize; 146 147 KASSERT(bnp != NULL || cnp != NULL || sp != NULL, 148 ("pcbmap: extra call")); 149 ASSERT_VOP_ELOCKED(DETOV(dep), "pcbmap"); 150 151 cn = dep->de_StartCluster; 152 /* 153 * The "file" that makes up the root directory is contiguous, 154 * permanently allocated, of fixed size, and is not made up of 155 * clusters. If the cluster number is beyond the end of the root 156 * directory, then return the number of clusters in the file. 157 */ 158 if (cn == MSDOSFSROOT) { 159 if (dep->de_Attributes & ATTR_DIRECTORY) { 160 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 161 if (cnp) 162 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 163 return (E2BIG); 164 } 165 if (bnp) 166 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 167 if (cnp) 168 *cnp = MSDOSFSROOT; 169 if (sp) 170 *sp = min(pmp->pm_bpcluster, 171 dep->de_FileSize - de_cn2off(pmp, findcn)); 172 return (0); 173 } else { /* just an empty file */ 174 if (cnp) 175 *cnp = 0; 176 return (E2BIG); 177 } 178 } 179 180 /* 181 * All other files do I/O in cluster sized blocks 182 */ 183 if (sp) 184 *sp = pmp->pm_bpcluster; 185 186 /* 187 * Rummage around in the fat cache, maybe we can avoid tromping 188 * thru every fat entry for the file. And, keep track of how far 189 * off the cache was from where we wanted to be. 190 */ 191 i = 0; 192 fc_lookup(dep, findcn, &i, &cn); 193 194 /* 195 * Handle all other files or directories the normal way. 196 */ 197 for (; i < findcn; i++) { 198 /* 199 * Stop with all reserved clusters, not just with EOF. 200 */ 201 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 202 goto hiteof; 203 byteoffset = FATOFS(pmp, cn); 204 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 205 if (bn != bp_bn) { 206 if (bp) 207 brelse(bp); 208 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 209 if (error) { 210 brelse(bp); 211 return (error); 212 } 213 bp_bn = bn; 214 } 215 prevcn = cn; 216 if (bo >= bsize) { 217 if (bp) 218 brelse(bp); 219 return (EIO); 220 } 221 if (FAT32(pmp)) 222 cn = getulong(&bp->b_data[bo]); 223 else 224 cn = getushort(&bp->b_data[bo]); 225 if (FAT12(pmp) && (prevcn & 1)) 226 cn >>= 4; 227 cn &= pmp->pm_fatmask; 228 229 /* 230 * Force the special cluster numbers 231 * to be the same for all cluster sizes 232 * to let the rest of msdosfs handle 233 * all cases the same. 234 */ 235 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 236 cn |= ~pmp->pm_fatmask; 237 } 238 239 if (!MSDOSFSEOF(pmp, cn)) { 240 if (bp) 241 brelse(bp); 242 if (bnp) 243 *bnp = cntobn(pmp, cn); 244 if (cnp) 245 *cnp = cn; 246 fc_setcache(dep, FC_LASTMAP, i, cn); 247 return (0); 248 } 249 250 hiteof:; 251 if (cnp) 252 *cnp = i; 253 if (bp) 254 brelse(bp); 255 /* update last file cluster entry in the fat cache */ 256 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 257 return (E2BIG); 258 } 259 260 /* 261 * Find the closest entry in the fat cache to the cluster we are looking 262 * for. 263 */ 264 static void 265 fc_lookup(dep, findcn, frcnp, fsrcnp) 266 struct denode *dep; 267 u_long findcn; 268 u_long *frcnp; 269 u_long *fsrcnp; 270 { 271 int i; 272 u_long cn; 273 struct fatcache *closest = 0; 274 275 ASSERT_VOP_LOCKED(DETOV(dep), "fc_lookup"); 276 277 for (i = 0; i < FC_SIZE; i++) { 278 cn = dep->de_fc[i].fc_frcn; 279 if (cn != FCE_EMPTY && cn <= findcn) { 280 if (closest == 0 || cn > closest->fc_frcn) 281 closest = &dep->de_fc[i]; 282 } 283 } 284 if (closest) { 285 *frcnp = closest->fc_frcn; 286 *fsrcnp = closest->fc_fsrcn; 287 } 288 } 289 290 /* 291 * Purge the fat cache in denode dep of all entries relating to file 292 * relative cluster frcn and beyond. 293 */ 294 void 295 fc_purge(dep, frcn) 296 struct denode *dep; 297 u_int frcn; 298 { 299 int i; 300 struct fatcache *fcp; 301 302 ASSERT_VOP_ELOCKED(DETOV(dep), "fc_purge"); 303 304 fcp = dep->de_fc; 305 for (i = 0; i < FC_SIZE; i++, fcp++) { 306 if (fcp->fc_frcn >= frcn) 307 fcp->fc_frcn = FCE_EMPTY; 308 } 309 } 310 311 /* 312 * Update the fat. 313 * If mirroring the fat, update all copies, with the first copy as last. 314 * Else update only the current fat (ignoring the others). 315 * 316 * pmp - msdosfsmount structure for filesystem to update 317 * bp - addr of modified fat block 318 * fatbn - block number relative to begin of filesystem of the modified fat block. 319 */ 320 static void 321 updatefats(pmp, bp, fatbn) 322 struct msdosfsmount *pmp; 323 struct buf *bp; 324 u_long fatbn; 325 { 326 struct buf *bpn; 327 int cleanfat, i; 328 329 #ifdef MSDOSFS_DEBUG 330 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 331 #endif 332 333 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 334 /* 335 * Now copy the block(s) of the modified fat to the other copies of 336 * the fat and write them out. This is faster than reading in the 337 * other fats and then writing them back out. This could tie up 338 * the fat for quite a while. Preventing others from accessing it. 339 * To prevent us from going after the fat quite so much we use 340 * delayed writes, unless they specfied "synchronous" when the 341 * filesystem was mounted. If synch is asked for then use 342 * bwrite()'s and really slow things down. 343 */ 344 if (fatbn != pmp->pm_fatblk || FAT12(pmp)) 345 cleanfat = 0; 346 else if (FAT16(pmp)) 347 cleanfat = 16; 348 else 349 cleanfat = 32; 350 for (i = 1; i < pmp->pm_FATs; i++) { 351 fatbn += pmp->pm_FATsecs; 352 /* getblk() never fails */ 353 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 354 0, 0, 0); 355 bcopy(bp->b_data, bpn->b_data, bp->b_bcount); 356 /* Force the clean bit on in the other copies. */ 357 if (cleanfat == 16) 358 ((u_int8_t *)bpn->b_data)[3] |= 0x80; 359 else if (cleanfat == 32) 360 ((u_int8_t *)bpn->b_data)[7] |= 0x08; 361 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 362 bwrite(bpn); 363 else 364 bdwrite(bpn); 365 } 366 } 367 368 /* 369 * Write out the first (or current) fat last. 370 */ 371 if (pmp->pm_mountp->mnt_flag & MNT_SYNCHRONOUS) 372 bwrite(bp); 373 else 374 bdwrite(bp); 375 } 376 377 /* 378 * Updating entries in 12 bit fats is a pain in the butt. 379 * 380 * The following picture shows where nibbles go when moving from a 12 bit 381 * cluster number into the appropriate bytes in the FAT. 382 * 383 * byte m byte m+1 byte m+2 384 * +----+----+ +----+----+ +----+----+ 385 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 386 * +----+----+ +----+----+ +----+----+ 387 * 388 * +----+----+----+ +----+----+----+ 389 * | 3 0 1 | | 4 5 2 | 390 * +----+----+----+ +----+----+----+ 391 * cluster n cluster n+1 392 * 393 * Where n is even. m = n + (n >> 2) 394 * 395 */ 396 static __inline void 397 usemap_alloc(pmp, cn) 398 struct msdosfsmount *pmp; 399 u_long cn; 400 { 401 402 MSDOSFS_ASSERT_MP_LOCKED(pmp); 403 404 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 405 pmp->pm_maxcluster)); 406 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 407 ("usemap_alloc on ro msdosfs mount")); 408 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 409 == 0, ("Allocating used sector %ld %ld %x", cn, cn % N_INUSEBITS, 410 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 411 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 412 KASSERT(pmp->pm_freeclustercount > 0, ("usemap_alloc: too little")); 413 pmp->pm_freeclustercount--; 414 pmp->pm_flags |= MSDOSFS_FSIMOD; 415 } 416 417 static __inline void 418 usemap_free(pmp, cn) 419 struct msdosfsmount *pmp; 420 u_long cn; 421 { 422 423 MSDOSFS_ASSERT_MP_LOCKED(pmp); 424 425 KASSERT(cn <= pmp->pm_maxcluster, ("cn too large %lu %lu", cn, 426 pmp->pm_maxcluster)); 427 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 428 ("usemap_free on ro msdosfs mount")); 429 pmp->pm_freeclustercount++; 430 pmp->pm_flags |= MSDOSFS_FSIMOD; 431 KASSERT((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 432 != 0, ("Freeing unused sector %ld %ld %x", cn, cn % N_INUSEBITS, 433 (unsigned)pmp->pm_inusemap[cn / N_INUSEBITS])); 434 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1 << (cn % N_INUSEBITS)); 435 } 436 437 int 438 clusterfree(pmp, cluster, oldcnp) 439 struct msdosfsmount *pmp; 440 u_long cluster; 441 u_long *oldcnp; 442 { 443 int error; 444 u_long oldcn; 445 446 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 447 if (error) 448 return (error); 449 /* 450 * If the cluster was successfully marked free, then update 451 * the count of free clusters, and turn off the "allocated" 452 * bit in the "in use" cluster bit map. 453 */ 454 MSDOSFS_LOCK_MP(pmp); 455 usemap_free(pmp, cluster); 456 MSDOSFS_UNLOCK_MP(pmp); 457 if (oldcnp) 458 *oldcnp = oldcn; 459 return (0); 460 } 461 462 /* 463 * Get or Set or 'Get and Set' the cluster'th entry in the fat. 464 * 465 * function - whether to get or set a fat entry 466 * pmp - address of the msdosfsmount structure for the filesystem 467 * whose fat is to be manipulated. 468 * cn - which cluster is of interest 469 * oldcontents - address of a word that is to receive the contents of the 470 * cluster'th entry if this is a get function 471 * newcontents - the new value to be written into the cluster'th element of 472 * the fat if this is a set function. 473 * 474 * This function can also be used to free a cluster by setting the fat entry 475 * for a cluster to 0. 476 * 477 * All copies of the fat are updated if this is a set function. NOTE: If 478 * fatentry() marks a cluster as free it does not update the inusemap in 479 * the msdosfsmount structure. This is left to the caller. 480 */ 481 int 482 fatentry(function, pmp, cn, oldcontents, newcontents) 483 int function; 484 struct msdosfsmount *pmp; 485 u_long cn; 486 u_long *oldcontents; 487 u_long newcontents; 488 { 489 int error; 490 u_long readcn; 491 u_long bn, bo, bsize, byteoffset; 492 struct buf *bp; 493 494 #ifdef MSDOSFS_DEBUG 495 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 496 function, pmp, cn, oldcontents, newcontents); 497 #endif 498 499 #ifdef DIAGNOSTIC 500 /* 501 * Be sure they asked us to do something. 502 */ 503 if ((function & (FAT_SET | FAT_GET)) == 0) { 504 #ifdef MSDOSFS_DEBUG 505 printf("fatentry(): function code doesn't specify get or set\n"); 506 #endif 507 return (EINVAL); 508 } 509 510 /* 511 * If they asked us to return a cluster number but didn't tell us 512 * where to put it, give them an error. 513 */ 514 if ((function & FAT_GET) && oldcontents == NULL) { 515 #ifdef MSDOSFS_DEBUG 516 printf("fatentry(): get function with no place to put result\n"); 517 #endif 518 return (EINVAL); 519 } 520 #endif 521 522 /* 523 * Be sure the requested cluster is in the filesystem. 524 */ 525 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 526 return (EINVAL); 527 528 byteoffset = FATOFS(pmp, cn); 529 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 530 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 531 if (error) { 532 brelse(bp); 533 return (error); 534 } 535 536 if (function & FAT_GET) { 537 if (FAT32(pmp)) 538 readcn = getulong(&bp->b_data[bo]); 539 else 540 readcn = getushort(&bp->b_data[bo]); 541 if (FAT12(pmp) & (cn & 1)) 542 readcn >>= 4; 543 readcn &= pmp->pm_fatmask; 544 /* map reserved fat entries to same values for all fats */ 545 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 546 readcn |= ~pmp->pm_fatmask; 547 *oldcontents = readcn; 548 } 549 if (function & FAT_SET) { 550 switch (pmp->pm_fatmask) { 551 case FAT12_MASK: 552 readcn = getushort(&bp->b_data[bo]); 553 if (cn & 1) { 554 readcn &= 0x000f; 555 readcn |= newcontents << 4; 556 } else { 557 readcn &= 0xf000; 558 readcn |= newcontents & 0xfff; 559 } 560 putushort(&bp->b_data[bo], readcn); 561 break; 562 case FAT16_MASK: 563 putushort(&bp->b_data[bo], newcontents); 564 break; 565 case FAT32_MASK: 566 /* 567 * According to spec we have to retain the 568 * high order bits of the fat entry. 569 */ 570 readcn = getulong(&bp->b_data[bo]); 571 readcn &= ~FAT32_MASK; 572 readcn |= newcontents & FAT32_MASK; 573 putulong(&bp->b_data[bo], readcn); 574 break; 575 } 576 updatefats(pmp, bp, bn); 577 bp = NULL; 578 pmp->pm_fmod = 1; 579 } 580 if (bp) 581 brelse(bp); 582 return (0); 583 } 584 585 /* 586 * Update a contiguous cluster chain 587 * 588 * pmp - mount point 589 * start - first cluster of chain 590 * count - number of clusters in chain 591 * fillwith - what to write into fat entry of last cluster 592 */ 593 static int 594 fatchain(pmp, start, count, fillwith) 595 struct msdosfsmount *pmp; 596 u_long start; 597 u_long count; 598 u_long fillwith; 599 { 600 int error; 601 u_long bn, bo, bsize, byteoffset, readcn, newc; 602 struct buf *bp; 603 604 #ifdef MSDOSFS_DEBUG 605 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 606 pmp, start, count, fillwith); 607 #endif 608 /* 609 * Be sure the clusters are in the filesystem. 610 */ 611 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 612 return (EINVAL); 613 614 while (count > 0) { 615 byteoffset = FATOFS(pmp, start); 616 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 617 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 618 if (error) { 619 brelse(bp); 620 return (error); 621 } 622 while (count > 0) { 623 start++; 624 newc = --count > 0 ? start : fillwith; 625 switch (pmp->pm_fatmask) { 626 case FAT12_MASK: 627 readcn = getushort(&bp->b_data[bo]); 628 if (start & 1) { 629 readcn &= 0xf000; 630 readcn |= newc & 0xfff; 631 } else { 632 readcn &= 0x000f; 633 readcn |= newc << 4; 634 } 635 putushort(&bp->b_data[bo], readcn); 636 bo++; 637 if (!(start & 1)) 638 bo++; 639 break; 640 case FAT16_MASK: 641 putushort(&bp->b_data[bo], newc); 642 bo += 2; 643 break; 644 case FAT32_MASK: 645 readcn = getulong(&bp->b_data[bo]); 646 readcn &= ~pmp->pm_fatmask; 647 readcn |= newc & pmp->pm_fatmask; 648 putulong(&bp->b_data[bo], readcn); 649 bo += 4; 650 break; 651 } 652 if (bo >= bsize) 653 break; 654 } 655 updatefats(pmp, bp, bn); 656 } 657 pmp->pm_fmod = 1; 658 return (0); 659 } 660 661 /* 662 * Check the length of a free cluster chain starting at start. 663 * 664 * pmp - mount point 665 * start - start of chain 666 * count - maximum interesting length 667 */ 668 static int 669 chainlength(pmp, start, count) 670 struct msdosfsmount *pmp; 671 u_long start; 672 u_long count; 673 { 674 u_long idx, max_idx; 675 u_int map; 676 u_long len; 677 678 MSDOSFS_ASSERT_MP_LOCKED(pmp); 679 680 if (start > pmp->pm_maxcluster) 681 return (0); 682 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 683 idx = start / N_INUSEBITS; 684 start %= N_INUSEBITS; 685 map = pmp->pm_inusemap[idx]; 686 map &= ~((1 << start) - 1); 687 if (map) { 688 len = ffs(map) - 1 - start; 689 len = MIN(len, count); 690 if (start + len > pmp->pm_maxcluster) 691 len = pmp->pm_maxcluster - start + 1; 692 return (len); 693 } 694 len = N_INUSEBITS - start; 695 if (len >= count) { 696 len = count; 697 if (start + len > pmp->pm_maxcluster) 698 len = pmp->pm_maxcluster - start + 1; 699 return (len); 700 } 701 while (++idx <= max_idx) { 702 if (len >= count) 703 break; 704 map = pmp->pm_inusemap[idx]; 705 if (map) { 706 len += ffs(map) - 1; 707 break; 708 } 709 len += N_INUSEBITS; 710 } 711 len = MIN(len, count); 712 if (start + len > pmp->pm_maxcluster) 713 len = pmp->pm_maxcluster - start + 1; 714 return (len); 715 } 716 717 /* 718 * Allocate contigous free clusters. 719 * 720 * pmp - mount point. 721 * start - start of cluster chain. 722 * count - number of clusters to allocate. 723 * fillwith - put this value into the fat entry for the 724 * last allocated cluster. 725 * retcluster - put the first allocated cluster's number here. 726 * got - how many clusters were actually allocated. 727 */ 728 static int 729 chainalloc(pmp, start, count, fillwith, retcluster, got) 730 struct msdosfsmount *pmp; 731 u_long start; 732 u_long count; 733 u_long fillwith; 734 u_long *retcluster; 735 u_long *got; 736 { 737 int error; 738 u_long cl, n; 739 740 MSDOSFS_ASSERT_MP_LOCKED(pmp); 741 KASSERT((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0, 742 ("chainalloc on ro msdosfs mount")); 743 744 for (cl = start, n = count; n-- > 0;) 745 usemap_alloc(pmp, cl++); 746 pmp->pm_nxtfree = start + count; 747 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 748 pmp->pm_nxtfree = CLUST_FIRST; 749 pmp->pm_flags |= MSDOSFS_FSIMOD; 750 error = fatchain(pmp, start, count, fillwith); 751 if (error != 0) { 752 for (cl = start, n = count; n-- > 0;) 753 usemap_free(pmp, cl++); 754 return (error); 755 } 756 #ifdef MSDOSFS_DEBUG 757 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 758 start, count); 759 #endif 760 if (retcluster) 761 *retcluster = start; 762 if (got) 763 *got = count; 764 return (0); 765 } 766 767 /* 768 * Allocate contiguous free clusters. 769 * 770 * pmp - mount point. 771 * start - preferred start of cluster chain. 772 * count - number of clusters requested. 773 * fillwith - put this value into the fat entry for the 774 * last allocated cluster. 775 * retcluster - put the first allocated cluster's number here. 776 * got - how many clusters were actually allocated. 777 */ 778 int 779 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 780 u_long fillwith, u_long *retcluster, u_long *got) 781 { 782 int error; 783 784 MSDOSFS_LOCK_MP(pmp); 785 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 786 MSDOSFS_UNLOCK_MP(pmp); 787 return (error); 788 } 789 790 static int 791 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 792 u_long fillwith, u_long *retcluster, u_long *got) 793 { 794 u_long idx; 795 u_long len, newst, foundl, cn, l; 796 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 797 u_int map; 798 799 MSDOSFS_ASSERT_MP_LOCKED(pmp); 800 801 #ifdef MSDOSFS_DEBUG 802 printf("clusteralloc(): find %lu clusters\n", count); 803 #endif 804 if (start) { 805 if ((len = chainlength(pmp, start, count)) >= count) 806 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 807 } else 808 len = 0; 809 810 newst = pmp->pm_nxtfree; 811 foundl = 0; 812 813 for (cn = newst; cn <= pmp->pm_maxcluster;) { 814 idx = cn / N_INUSEBITS; 815 map = pmp->pm_inusemap[idx]; 816 map |= (1 << (cn % N_INUSEBITS)) - 1; 817 if (map != FULL_RUN) { 818 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 819 if ((l = chainlength(pmp, cn, count)) >= count) 820 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 821 if (l > foundl) { 822 foundcn = cn; 823 foundl = l; 824 } 825 cn += l + 1; 826 continue; 827 } 828 cn += N_INUSEBITS - cn % N_INUSEBITS; 829 } 830 for (cn = 0; cn < newst;) { 831 idx = cn / N_INUSEBITS; 832 map = pmp->pm_inusemap[idx]; 833 map |= (1 << (cn % N_INUSEBITS)) - 1; 834 if (map != FULL_RUN) { 835 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 836 if ((l = chainlength(pmp, cn, count)) >= count) 837 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 838 if (l > foundl) { 839 foundcn = cn; 840 foundl = l; 841 } 842 cn += l + 1; 843 continue; 844 } 845 cn += N_INUSEBITS - cn % N_INUSEBITS; 846 } 847 848 if (!foundl) 849 return (ENOSPC); 850 851 if (len) 852 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 853 else 854 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 855 } 856 857 858 /* 859 * Free a chain of clusters. 860 * 861 * pmp - address of the msdosfs mount structure for the filesystem 862 * containing the cluster chain to be freed. 863 * startcluster - number of the 1st cluster in the chain of clusters to be 864 * freed. 865 */ 866 int 867 freeclusterchain(pmp, cluster) 868 struct msdosfsmount *pmp; 869 u_long cluster; 870 { 871 int error; 872 struct buf *bp = NULL; 873 u_long bn, bo, bsize, byteoffset; 874 u_long readcn, lbn = -1; 875 876 MSDOSFS_LOCK_MP(pmp); 877 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 878 byteoffset = FATOFS(pmp, cluster); 879 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 880 if (lbn != bn) { 881 if (bp) 882 updatefats(pmp, bp, lbn); 883 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 884 if (error) { 885 brelse(bp); 886 MSDOSFS_UNLOCK_MP(pmp); 887 return (error); 888 } 889 lbn = bn; 890 } 891 usemap_free(pmp, cluster); 892 switch (pmp->pm_fatmask) { 893 case FAT12_MASK: 894 readcn = getushort(&bp->b_data[bo]); 895 if (cluster & 1) { 896 cluster = readcn >> 4; 897 readcn &= 0x000f; 898 readcn |= MSDOSFSFREE << 4; 899 } else { 900 cluster = readcn; 901 readcn &= 0xf000; 902 readcn |= MSDOSFSFREE & 0xfff; 903 } 904 putushort(&bp->b_data[bo], readcn); 905 break; 906 case FAT16_MASK: 907 cluster = getushort(&bp->b_data[bo]); 908 putushort(&bp->b_data[bo], MSDOSFSFREE); 909 break; 910 case FAT32_MASK: 911 cluster = getulong(&bp->b_data[bo]); 912 putulong(&bp->b_data[bo], 913 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 914 break; 915 } 916 cluster &= pmp->pm_fatmask; 917 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 918 cluster |= pmp->pm_fatmask; 919 } 920 if (bp) 921 updatefats(pmp, bp, bn); 922 MSDOSFS_UNLOCK_MP(pmp); 923 return (0); 924 } 925 926 /* 927 * Read in fat blocks looking for free clusters. For every free cluster 928 * found turn off its corresponding bit in the pm_inusemap. 929 */ 930 int 931 fillinusemap(pmp) 932 struct msdosfsmount *pmp; 933 { 934 struct buf *bp = NULL; 935 u_long cn, readcn; 936 int error; 937 u_long bn, bo, bsize, byteoffset; 938 939 MSDOSFS_ASSERT_MP_LOCKED(pmp); 940 941 /* 942 * Mark all clusters in use, we mark the free ones in the fat scan 943 * loop further down. 944 */ 945 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 946 pmp->pm_inusemap[cn] = FULL_RUN; 947 948 /* 949 * Figure how many free clusters are in the filesystem by ripping 950 * through the fat counting the number of entries whose content is 951 * zero. These represent free clusters. 952 */ 953 pmp->pm_freeclustercount = 0; 954 for (cn = CLUST_FIRST; cn <= pmp->pm_maxcluster; cn++) { 955 byteoffset = FATOFS(pmp, cn); 956 bo = byteoffset % pmp->pm_fatblocksize; 957 if (!bo || !bp) { 958 /* Read new FAT block */ 959 if (bp) 960 brelse(bp); 961 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 962 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 963 if (error) { 964 brelse(bp); 965 return (error); 966 } 967 } 968 if (FAT32(pmp)) 969 readcn = getulong(&bp->b_data[bo]); 970 else 971 readcn = getushort(&bp->b_data[bo]); 972 if (FAT12(pmp) && (cn & 1)) 973 readcn >>= 4; 974 readcn &= pmp->pm_fatmask; 975 976 if (readcn == CLUST_FREE) 977 usemap_free(pmp, cn); 978 } 979 if (bp != NULL) 980 brelse(bp); 981 982 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster + 983 N_INUSEBITS) / N_INUSEBITS; cn++) 984 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1 << (cn % N_INUSEBITS); 985 986 return (0); 987 } 988 989 /* 990 * Allocate a new cluster and chain it onto the end of the file. 991 * 992 * dep - the file to extend 993 * count - number of clusters to allocate 994 * bpp - where to return the address of the buf header for the first new 995 * file block 996 * ncp - where to put cluster number of the first newly allocated cluster 997 * If this pointer is 0, do not return the cluster number. 998 * flags - see fat.h 999 * 1000 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 1001 * the de_flag field of the denode and it does not change the de_FileSize 1002 * field. This is left for the caller to do. 1003 */ 1004 int 1005 extendfile(dep, count, bpp, ncp, flags) 1006 struct denode *dep; 1007 u_long count; 1008 struct buf **bpp; 1009 u_long *ncp; 1010 int flags; 1011 { 1012 int error; 1013 u_long frcn; 1014 u_long cn, got; 1015 struct msdosfsmount *pmp = dep->de_pmp; 1016 struct buf *bp; 1017 daddr_t blkno; 1018 1019 /* 1020 * Don't try to extend the root directory 1021 */ 1022 if (dep->de_StartCluster == MSDOSFSROOT 1023 && (dep->de_Attributes & ATTR_DIRECTORY)) { 1024 #ifdef MSDOSFS_DEBUG 1025 printf("extendfile(): attempt to extend root directory\n"); 1026 #endif 1027 return (ENOSPC); 1028 } 1029 1030 /* 1031 * If the "file's last cluster" cache entry is empty, and the file 1032 * is not empty, then fill the cache entry by calling pcbmap(). 1033 */ 1034 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 1035 dep->de_StartCluster != 0) { 1036 error = pcbmap(dep, 0xffff, 0, &cn, 0); 1037 /* we expect it to return E2BIG */ 1038 if (error != E2BIG) 1039 return (error); 1040 } 1041 1042 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 1043 dep->de_fc[FC_LASTFC].fc_frcn; 1044 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 1045 dep->de_fc[FC_LASTFC].fc_fsrcn; 1046 while (count > 0) { 1047 /* 1048 * Allocate a new cluster chain and cat onto the end of the 1049 * file. 1050 * If the file is empty we make de_StartCluster point 1051 * to the new block. Note that de_StartCluster being 1052 * 0 is sufficient to be sure the file is empty since 1053 * we exclude attempts to extend the root directory 1054 * above, and the root dir is the only file with a 1055 * startcluster of 0 that has blocks allocated (sort 1056 * of). 1057 */ 1058 if (dep->de_StartCluster == 0) 1059 cn = 0; 1060 else 1061 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1062 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1063 if (error) 1064 return (error); 1065 1066 count -= got; 1067 1068 /* 1069 * Give them the filesystem relative cluster number if they want 1070 * it. 1071 */ 1072 if (ncp) { 1073 *ncp = cn; 1074 ncp = NULL; 1075 } 1076 1077 if (dep->de_StartCluster == 0) { 1078 dep->de_StartCluster = cn; 1079 frcn = 0; 1080 } else { 1081 error = fatentry(FAT_SET, pmp, 1082 dep->de_fc[FC_LASTFC].fc_fsrcn, 1083 0, cn); 1084 if (error) { 1085 clusterfree(pmp, cn, NULL); 1086 return (error); 1087 } 1088 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1089 } 1090 1091 /* 1092 * Update the "last cluster of the file" entry in the denode's fat 1093 * cache. 1094 */ 1095 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1096 1097 if (flags & DE_CLEAR) { 1098 while (got-- > 0) { 1099 /* 1100 * Get the buf header for the new block of the file. 1101 */ 1102 if (dep->de_Attributes & ATTR_DIRECTORY) 1103 bp = getblk(pmp->pm_devvp, 1104 cntobn(pmp, cn++), 1105 pmp->pm_bpcluster, 0, 0, 0); 1106 else { 1107 bp = getblk(DETOV(dep), 1108 frcn++, 1109 pmp->pm_bpcluster, 0, 0, 0); 1110 /* 1111 * Do the bmap now, as in msdosfs_write 1112 */ 1113 if (pcbmap(dep, 1114 bp->b_lblkno, 1115 &blkno, 0, 0)) 1116 bp->b_blkno = -1; 1117 if (bp->b_blkno == -1) 1118 panic("extendfile: pcbmap"); 1119 else 1120 bp->b_blkno = blkno; 1121 } 1122 vfs_bio_clrbuf(bp); 1123 if (bpp) { 1124 *bpp = bp; 1125 bpp = NULL; 1126 } else 1127 bdwrite(bp); 1128 } 1129 } 1130 } 1131 1132 return (0); 1133 } 1134 1135 /*- 1136 * Routine to mark a FAT16 or FAT32 volume as "clean" or "dirty" by 1137 * manipulating the upper bit of the FAT entry for cluster 1. Note that 1138 * this bit is not defined for FAT12 volumes, which are always assumed to 1139 * be clean. 1140 * 1141 * The fatentry() routine only works on cluster numbers that a file could 1142 * occupy, so it won't manipulate the entry for cluster 1. So we have to do 1143 * it here. The code was stolen from fatentry() and tailored for cluster 1. 1144 * 1145 * Inputs: 1146 * pmp The MS-DOS volume to mark 1147 * dirty Non-zero if the volume should be marked dirty; zero if it 1148 * should be marked clean 1149 * 1150 * Result: 1151 * 0 Success 1152 * EROFS Volume is read-only 1153 * ? (other errors from called routines) 1154 */ 1155 int 1156 markvoldirty(struct msdosfsmount *pmp, int dirty) 1157 { 1158 struct buf *bp; 1159 u_long bn, bo, bsize, byteoffset, fatval; 1160 int error; 1161 1162 /* 1163 * FAT12 does not support a "clean" bit, so don't do anything for 1164 * FAT12. 1165 */ 1166 if (FAT12(pmp)) 1167 return (0); 1168 1169 /* Can't change the bit on a read-only filesystem. */ 1170 if (pmp->pm_flags & MSDOSFSMNT_RONLY) 1171 return (EROFS); 1172 1173 /* 1174 * Fetch the block containing the FAT entry. It is given by the 1175 * pseudo-cluster 1. 1176 */ 1177 byteoffset = FATOFS(pmp, 1); 1178 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 1179 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 1180 if (error) { 1181 brelse(bp); 1182 return (error); 1183 } 1184 1185 /* 1186 * Get the current value of the FAT entry and set/clear the relevant 1187 * bit. Dirty means clear the "clean" bit; clean means set the 1188 * "clean" bit. 1189 */ 1190 if (FAT32(pmp)) { 1191 /* FAT32 uses bit 27. */ 1192 fatval = getulong(&bp->b_data[bo]); 1193 if (dirty) 1194 fatval &= 0xF7FFFFFF; 1195 else 1196 fatval |= 0x08000000; 1197 putulong(&bp->b_data[bo], fatval); 1198 } else { 1199 /* Must be FAT16; use bit 15. */ 1200 fatval = getushort(&bp->b_data[bo]); 1201 if (dirty) 1202 fatval &= 0x7FFF; 1203 else 1204 fatval |= 0x8000; 1205 putushort(&bp->b_data[bo], fatval); 1206 } 1207 1208 /* Write out the modified FAT block synchronously. */ 1209 return (bwrite(bp)); 1210 }
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