1 /* 2 * linux/fs/hfs/extent.c 3 * 4 * Copyright (C) 1995-1997 Paul H. Hargrove 5 * (C) 2003 Ardis Technologies <roman@ardistech.com> 6 * This file may be distributed under the terms of the GNU General Public License. 7 * 8 * This file contains the functions related to the extents B-tree. 9 */ 10 11 #include <linux/pagemap.h> 12 13 #include "hfs_fs.h" 14 #include "btree.h" 15 16 /*================ File-local functions ================*/ 17 18 /* 19 * build_key 20 */ 21 static void hfs_ext_build_key(hfs_btree_key *key, u32 cnid, u16 block, u8 type) 22 { 23 key->key_len = 7; 24 key->ext.FkType = type; 25 key->ext.FNum = cpu_to_be32(cnid); 26 key->ext.FABN = cpu_to_be16(block); 27 } 28 29 /* 30 * hfs_ext_compare() 31 * 32 * Description: 33 * This is the comparison function used for the extents B-tree. In 34 * comparing extent B-tree entries, the file id is the most 35 * significant field (compared as unsigned ints); the fork type is 36 * the second most significant field (compared as unsigned chars); 37 * and the allocation block number field is the least significant 38 * (compared as unsigned ints). 39 * Input Variable(s): 40 * struct hfs_ext_key *key1: pointer to the first key to compare 41 * struct hfs_ext_key *key2: pointer to the second key to compare 42 * Output Variable(s): 43 * NONE 44 * Returns: 45 * int: negative if key1<key2, positive if key1>key2, and 0 if key1==key2 46 * Preconditions: 47 * key1 and key2 point to "valid" (struct hfs_ext_key)s. 48 * Postconditions: 49 * This function has no side-effects */ 50 int hfs_ext_keycmp(const btree_key *key1, const btree_key *key2) 51 { 52 __be32 fnum1, fnum2; 53 __be16 block1, block2; 54 55 fnum1 = key1->ext.FNum; 56 fnum2 = key2->ext.FNum; 57 if (fnum1 != fnum2) 58 return be32_to_cpu(fnum1) < be32_to_cpu(fnum2) ? -1 : 1; 59 if (key1->ext.FkType != key2->ext.FkType) 60 return key1->ext.FkType < key2->ext.FkType ? -1 : 1; 61 62 block1 = key1->ext.FABN; 63 block2 = key2->ext.FABN; 64 if (block1 == block2) 65 return 0; 66 return be16_to_cpu(block1) < be16_to_cpu(block2) ? -1 : 1; 67 } 68 69 /* 70 * hfs_ext_find_block 71 * 72 * Find a block within an extent record 73 */ 74 static u16 hfs_ext_find_block(struct hfs_extent *ext, u16 off) 75 { 76 int i; 77 u16 count; 78 79 for (i = 0; i < 3; ext++, i++) { 80 count = be16_to_cpu(ext->count); 81 if (off < count) 82 return be16_to_cpu(ext->block) + off; 83 off -= count; 84 } 85 /* panic? */ 86 return 0; 87 } 88 89 static int hfs_ext_block_count(struct hfs_extent *ext) 90 { 91 int i; 92 u16 count = 0; 93 94 for (i = 0; i < 3; ext++, i++) 95 count += be16_to_cpu(ext->count); 96 return count; 97 } 98 99 static u16 hfs_ext_lastblock(struct hfs_extent *ext) 100 { 101 int i; 102 103 ext += 2; 104 for (i = 0; i < 2; ext--, i++) 105 if (ext->count) 106 break; 107 return be16_to_cpu(ext->block) + be16_to_cpu(ext->count); 108 } 109 110 static void __hfs_ext_write_extent(struct inode *inode, struct hfs_find_data *fd) 111 { 112 int res; 113 114 hfs_ext_build_key(fd->search_key, inode->i_ino, HFS_I(inode)->cached_start, 115 HFS_IS_RSRC(inode) ? HFS_FK_RSRC : HFS_FK_DATA); 116 res = hfs_brec_find(fd); 117 if (HFS_I(inode)->flags & HFS_FLG_EXT_NEW) { 118 if (res != -ENOENT) 119 return; 120 hfs_brec_insert(fd, HFS_I(inode)->cached_extents, sizeof(hfs_extent_rec)); 121 HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW); 122 } else { 123 if (res) 124 return; 125 hfs_bnode_write(fd->bnode, HFS_I(inode)->cached_extents, fd->entryoffset, fd->entrylength); 126 HFS_I(inode)->flags &= ~HFS_FLG_EXT_DIRTY; 127 } 128 } 129 130 void hfs_ext_write_extent(struct inode *inode) 131 { 132 struct hfs_find_data fd; 133 134 if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY) { 135 hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd); 136 __hfs_ext_write_extent(inode, &fd); 137 hfs_find_exit(&fd); 138 } 139 } 140 141 static inline int __hfs_ext_read_extent(struct hfs_find_data *fd, struct hfs_extent *extent, 142 u32 cnid, u32 block, u8 type) 143 { 144 int res; 145 146 hfs_ext_build_key(fd->search_key, cnid, block, type); 147 fd->key->ext.FNum = 0; 148 res = hfs_brec_find(fd); 149 if (res && res != -ENOENT) 150 return res; 151 if (fd->key->ext.FNum != fd->search_key->ext.FNum || 152 fd->key->ext.FkType != fd->search_key->ext.FkType) 153 return -ENOENT; 154 if (fd->entrylength != sizeof(hfs_extent_rec)) 155 return -EIO; 156 hfs_bnode_read(fd->bnode, extent, fd->entryoffset, sizeof(hfs_extent_rec)); 157 return 0; 158 } 159 160 static inline int __hfs_ext_cache_extent(struct hfs_find_data *fd, struct inode *inode, u32 block) 161 { 162 int res; 163 164 if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY) 165 __hfs_ext_write_extent(inode, fd); 166 167 res = __hfs_ext_read_extent(fd, HFS_I(inode)->cached_extents, inode->i_ino, 168 block, HFS_IS_RSRC(inode) ? HFS_FK_RSRC : HFS_FK_DATA); 169 if (!res) { 170 HFS_I(inode)->cached_start = be16_to_cpu(fd->key->ext.FABN); 171 HFS_I(inode)->cached_blocks = hfs_ext_block_count(HFS_I(inode)->cached_extents); 172 } else { 173 HFS_I(inode)->cached_start = HFS_I(inode)->cached_blocks = 0; 174 HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW); 175 } 176 return res; 177 } 178 179 static int hfs_ext_read_extent(struct inode *inode, u16 block) 180 { 181 struct hfs_find_data fd; 182 int res; 183 184 if (block >= HFS_I(inode)->cached_start && 185 block < HFS_I(inode)->cached_start + HFS_I(inode)->cached_blocks) 186 return 0; 187 188 hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd); 189 res = __hfs_ext_cache_extent(&fd, inode, block); 190 hfs_find_exit(&fd); 191 return res; 192 } 193 194 static void hfs_dump_extent(struct hfs_extent *extent) 195 { 196 int i; 197 198 dprint(DBG_EXTENT, " "); 199 for (i = 0; i < 3; i++) 200 dprint(DBG_EXTENT, " %u:%u", be16_to_cpu(extent[i].block), 201 be16_to_cpu(extent[i].count)); 202 dprint(DBG_EXTENT, "\n"); 203 } 204 205 static int hfs_add_extent(struct hfs_extent *extent, u16 offset, 206 u16 alloc_block, u16 block_count) 207 { 208 u16 count, start; 209 int i; 210 211 hfs_dump_extent(extent); 212 for (i = 0; i < 3; extent++, i++) { 213 count = be16_to_cpu(extent->count); 214 if (offset == count) { 215 start = be16_to_cpu(extent->block); 216 if (alloc_block != start + count) { 217 if (++i >= 3) 218 return -ENOSPC; 219 extent++; 220 extent->block = cpu_to_be16(alloc_block); 221 } else 222 block_count += count; 223 extent->count = cpu_to_be16(block_count); 224 return 0; 225 } else if (offset < count) 226 break; 227 offset -= count; 228 } 229 /* panic? */ 230 return -EIO; 231 } 232 233 static int hfs_free_extents(struct super_block *sb, struct hfs_extent *extent, 234 u16 offset, u16 block_nr) 235 { 236 u16 count, start; 237 int i; 238 239 hfs_dump_extent(extent); 240 for (i = 0; i < 3; extent++, i++) { 241 count = be16_to_cpu(extent->count); 242 if (offset == count) 243 goto found; 244 else if (offset < count) 245 break; 246 offset -= count; 247 } 248 /* panic? */ 249 return -EIO; 250 found: 251 for (;;) { 252 start = be16_to_cpu(extent->block); 253 if (count <= block_nr) { 254 hfs_clear_vbm_bits(sb, start, count); 255 extent->block = 0; 256 extent->count = 0; 257 block_nr -= count; 258 } else { 259 count -= block_nr; 260 hfs_clear_vbm_bits(sb, start + count, block_nr); 261 extent->count = cpu_to_be16(count); 262 block_nr = 0; 263 } 264 if (!block_nr || !i) 265 return 0; 266 i--; 267 extent--; 268 count = be16_to_cpu(extent->count); 269 } 270 } 271 272 int hfs_free_fork(struct super_block *sb, struct hfs_cat_file *file, int type) 273 { 274 struct hfs_find_data fd; 275 u32 total_blocks, blocks, start; 276 u32 cnid = be32_to_cpu(file->FlNum); 277 struct hfs_extent *extent; 278 int res, i; 279 280 if (type == HFS_FK_DATA) { 281 total_blocks = be32_to_cpu(file->PyLen); 282 extent = file->ExtRec; 283 } else { 284 total_blocks = be32_to_cpu(file->RPyLen); 285 extent = file->RExtRec; 286 } 287 total_blocks /= HFS_SB(sb)->alloc_blksz; 288 if (!total_blocks) 289 return 0; 290 291 blocks = 0; 292 for (i = 0; i < 3; extent++, i++) 293 blocks += be16_to_cpu(extent[i].count); 294 295 res = hfs_free_extents(sb, extent, blocks, blocks); 296 if (res) 297 return res; 298 if (total_blocks == blocks) 299 return 0; 300 301 hfs_find_init(HFS_SB(sb)->ext_tree, &fd); 302 do { 303 res = __hfs_ext_read_extent(&fd, extent, cnid, total_blocks, type); 304 if (res) 305 break; 306 start = be16_to_cpu(fd.key->ext.FABN); 307 hfs_free_extents(sb, extent, total_blocks - start, total_blocks); 308 hfs_brec_remove(&fd); 309 total_blocks = start; 310 } while (total_blocks > blocks); 311 hfs_find_exit(&fd); 312 313 return res; 314 } 315 316 /* 317 * hfs_get_block 318 */ 319 int hfs_get_block(struct inode *inode, sector_t block, 320 struct buffer_head *bh_result, int create) 321 { 322 struct super_block *sb; 323 u16 dblock, ablock; 324 int res; 325 326 sb = inode->i_sb; 327 /* Convert inode block to disk allocation block */ 328 ablock = (u32)block / HFS_SB(sb)->fs_div; 329 330 if (block >= HFS_I(inode)->fs_blocks) { 331 if (block > HFS_I(inode)->fs_blocks || !create) 332 return -EIO; 333 if (ablock >= HFS_I(inode)->alloc_blocks) { 334 res = hfs_extend_file(inode); 335 if (res) 336 return res; 337 } 338 } else 339 create = 0; 340 341 if (ablock < HFS_I(inode)->first_blocks) { 342 dblock = hfs_ext_find_block(HFS_I(inode)->first_extents, ablock); 343 goto done; 344 } 345 346 down(&HFS_I(inode)->extents_lock); 347 res = hfs_ext_read_extent(inode, ablock); 348 if (!res) 349 dblock = hfs_ext_find_block(HFS_I(inode)->cached_extents, 350 ablock - HFS_I(inode)->cached_start); 351 else { 352 up(&HFS_I(inode)->extents_lock); 353 return -EIO; 354 } 355 up(&HFS_I(inode)->extents_lock); 356 357 done: 358 map_bh(bh_result, sb, HFS_SB(sb)->fs_start + 359 dblock * HFS_SB(sb)->fs_div + 360 (u32)block % HFS_SB(sb)->fs_div); 361 362 if (create) { 363 set_buffer_new(bh_result); 364 HFS_I(inode)->phys_size += sb->s_blocksize; 365 HFS_I(inode)->fs_blocks++; 366 inode_add_bytes(inode, sb->s_blocksize); 367 mark_inode_dirty(inode); 368 } 369 return 0; 370 } 371 372 int hfs_extend_file(struct inode *inode) 373 { 374 struct super_block *sb = inode->i_sb; 375 u32 start, len, goal; 376 int res; 377 378 down(&HFS_I(inode)->extents_lock); 379 if (HFS_I(inode)->alloc_blocks == HFS_I(inode)->first_blocks) 380 goal = hfs_ext_lastblock(HFS_I(inode)->first_extents); 381 else { 382 res = hfs_ext_read_extent(inode, HFS_I(inode)->alloc_blocks); 383 if (res) 384 goto out; 385 goal = hfs_ext_lastblock(HFS_I(inode)->cached_extents); 386 } 387 388 len = HFS_I(inode)->clump_blocks; 389 start = hfs_vbm_search_free(sb, goal, &len); 390 if (!len) { 391 res = -ENOSPC; 392 goto out; 393 } 394 395 dprint(DBG_EXTENT, "extend %lu: %u,%u\n", inode->i_ino, start, len); 396 if (HFS_I(inode)->alloc_blocks == HFS_I(inode)->first_blocks) { 397 if (!HFS_I(inode)->first_blocks) { 398 dprint(DBG_EXTENT, "first extents\n"); 399 /* no extents yet */ 400 HFS_I(inode)->first_extents[0].block = cpu_to_be16(start); 401 HFS_I(inode)->first_extents[0].count = cpu_to_be16(len); 402 res = 0; 403 } else { 404 /* try to append to extents in inode */ 405 res = hfs_add_extent(HFS_I(inode)->first_extents, 406 HFS_I(inode)->alloc_blocks, 407 start, len); 408 if (res == -ENOSPC) 409 goto insert_extent; 410 } 411 if (!res) { 412 hfs_dump_extent(HFS_I(inode)->first_extents); 413 HFS_I(inode)->first_blocks += len; 414 } 415 } else { 416 res = hfs_add_extent(HFS_I(inode)->cached_extents, 417 HFS_I(inode)->alloc_blocks - 418 HFS_I(inode)->cached_start, 419 start, len); 420 if (!res) { 421 hfs_dump_extent(HFS_I(inode)->cached_extents); 422 HFS_I(inode)->flags |= HFS_FLG_EXT_DIRTY; 423 HFS_I(inode)->cached_blocks += len; 424 } else if (res == -ENOSPC) 425 goto insert_extent; 426 } 427 out: 428 up(&HFS_I(inode)->extents_lock); 429 if (!res) { 430 HFS_I(inode)->alloc_blocks += len; 431 mark_inode_dirty(inode); 432 if (inode->i_ino < HFS_FIRSTUSER_CNID) 433 set_bit(HFS_FLG_ALT_MDB_DIRTY, &HFS_SB(sb)->flags); 434 set_bit(HFS_FLG_MDB_DIRTY, &HFS_SB(sb)->flags); 435 sb->s_dirt = 1; 436 } 437 return res; 438 439 insert_extent: 440 dprint(DBG_EXTENT, "insert new extent\n"); 441 hfs_ext_write_extent(inode); 442 443 memset(HFS_I(inode)->cached_extents, 0, sizeof(hfs_extent_rec)); 444 HFS_I(inode)->cached_extents[0].block = cpu_to_be16(start); 445 HFS_I(inode)->cached_extents[0].count = cpu_to_be16(len); 446 hfs_dump_extent(HFS_I(inode)->cached_extents); 447 HFS_I(inode)->flags |= HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW; 448 HFS_I(inode)->cached_start = HFS_I(inode)->alloc_blocks; 449 HFS_I(inode)->cached_blocks = len; 450 451 res = 0; 452 goto out; 453 } 454 455 void hfs_file_truncate(struct inode *inode) 456 { 457 struct super_block *sb = inode->i_sb; 458 struct hfs_find_data fd; 459 u16 blk_cnt, alloc_cnt, start; 460 u32 size; 461 int res; 462 463 dprint(DBG_INODE, "truncate: %lu, %Lu -> %Lu\n", inode->i_ino, 464 (long long)HFS_I(inode)->phys_size, inode->i_size); 465 if (inode->i_size > HFS_I(inode)->phys_size) { 466 struct address_space *mapping = inode->i_mapping; 467 struct page *page; 468 int res; 469 470 size = inode->i_size - 1; 471 page = grab_cache_page(mapping, size >> PAGE_CACHE_SHIFT); 472 if (!page) 473 return; 474 size &= PAGE_CACHE_SIZE - 1; 475 size++; 476 res = mapping->a_ops->prepare_write(NULL, page, size, size); 477 if (!res) 478 res = mapping->a_ops->commit_write(NULL, page, size, size); 479 if (res) 480 inode->i_size = HFS_I(inode)->phys_size; 481 unlock_page(page); 482 page_cache_release(page); 483 mark_inode_dirty(inode); 484 return; 485 } else if (inode->i_size == HFS_I(inode)->phys_size) 486 return; 487 size = inode->i_size + HFS_SB(sb)->alloc_blksz - 1; 488 blk_cnt = size / HFS_SB(sb)->alloc_blksz; 489 alloc_cnt = HFS_I(inode)->alloc_blocks; 490 if (blk_cnt == alloc_cnt) 491 goto out; 492 493 down(&HFS_I(inode)->extents_lock); 494 hfs_find_init(HFS_SB(sb)->ext_tree, &fd); 495 while (1) { 496 if (alloc_cnt == HFS_I(inode)->first_blocks) { 497 hfs_free_extents(sb, HFS_I(inode)->first_extents, 498 alloc_cnt, alloc_cnt - blk_cnt); 499 hfs_dump_extent(HFS_I(inode)->first_extents); 500 HFS_I(inode)->first_blocks = blk_cnt; 501 break; 502 } 503 res = __hfs_ext_cache_extent(&fd, inode, alloc_cnt); 504 if (res) 505 break; 506 start = HFS_I(inode)->cached_start; 507 hfs_free_extents(sb, HFS_I(inode)->cached_extents, 508 alloc_cnt - start, alloc_cnt - blk_cnt); 509 hfs_dump_extent(HFS_I(inode)->cached_extents); 510 if (blk_cnt > start) { 511 HFS_I(inode)->flags |= HFS_FLG_EXT_DIRTY; 512 break; 513 } 514 alloc_cnt = start; 515 HFS_I(inode)->cached_start = HFS_I(inode)->cached_blocks = 0; 516 HFS_I(inode)->flags &= ~(HFS_FLG_EXT_DIRTY|HFS_FLG_EXT_NEW); 517 hfs_brec_remove(&fd); 518 } 519 hfs_find_exit(&fd); 520 up(&HFS_I(inode)->extents_lock); 521 522 HFS_I(inode)->alloc_blocks = blk_cnt; 523 out: 524 HFS_I(inode)->phys_size = inode->i_size; 525 HFS_I(inode)->fs_blocks = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits; 526 inode_set_bytes(inode, HFS_I(inode)->fs_blocks << sb->s_blocksize_bits); 527 mark_inode_dirty(inode); 528 } 529